Thu, 19 Jul 2012 15:15:54 -0700
7114678: G1: various small fixes, code cleanup, and refactoring
Summary: Various cleanups as a prelude to introducing iterators for HeapRegions.
Reviewed-by: johnc, 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/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
65 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
77 class YoungList : public CHeapObj<mtGC> {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 uint _length;
89 uint _survivor_length;
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
94 void empty_list(HeapRegion* list);
96 public:
97 YoungList(G1CollectedHeap* g1h);
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 uint length() { return _length; }
105 uint survivor_length() { return _survivor_length; }
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return (size_t) survivor_length() * HeapRegion::GrainBytes;
118 }
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
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 // refence processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
168 bool do_object_b(oop p);
169 };
171 class SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
189 class RefineCardTableEntryClosure;
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_GenCollectForPermanentAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
201 // Closures used in implementation.
202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
203 friend class G1ParCopyClosure;
204 friend class G1IsAliveClosure;
205 friend class G1EvacuateFollowersClosure;
206 friend class G1ParScanThreadState;
207 friend class G1ParScanClosureSuper;
208 friend class G1ParEvacuateFollowersClosure;
209 friend class G1ParTask;
210 friend class G1FreeGarbageRegionClosure;
211 friend class RefineCardTableEntryClosure;
212 friend class G1PrepareCompactClosure;
213 friend class RegionSorter;
214 friend class RegionResetter;
215 friend class CountRCClosure;
216 friend class EvacPopObjClosure;
217 friend class G1ParCleanupCTTask;
219 // Other related classes.
220 friend class G1MarkSweep;
222 private:
223 // The one and only G1CollectedHeap, so static functions can find it.
224 static G1CollectedHeap* _g1h;
226 static size_t _humongous_object_threshold_in_words;
228 // Storage for the G1 heap (excludes the permanent generation).
229 VirtualSpace _g1_storage;
230 MemRegion _g1_reserved;
232 // The part of _g1_storage that is currently committed.
233 MemRegion _g1_committed;
235 // The master free list. It will satisfy all new region allocations.
236 MasterFreeRegionList _free_list;
238 // The secondary free list which contains regions that have been
239 // freed up during the cleanup process. This will be appended to the
240 // master free list when appropriate.
241 SecondaryFreeRegionList _secondary_free_list;
243 // It keeps track of the old regions.
244 MasterOldRegionSet _old_set;
246 // It keeps track of the humongous regions.
247 MasterHumongousRegionSet _humongous_set;
249 // The number of regions we could create by expansion.
250 uint _expansion_regions;
252 // The block offset table for the G1 heap.
253 G1BlockOffsetSharedArray* _bot_shared;
255 // Tears down the region sets / lists so that they are empty and the
256 // regions on the heap do not belong to a region set / list. The
257 // only exception is the humongous set which we leave unaltered. If
258 // free_list_only is true, it will only tear down the master free
259 // list. It is called before a Full GC (free_list_only == false) or
260 // before heap shrinking (free_list_only == true).
261 void tear_down_region_sets(bool free_list_only);
263 // Rebuilds the region sets / lists so that they are repopulated to
264 // reflect the contents of the heap. The only exception is the
265 // humongous set which was not torn down in the first place. If
266 // free_list_only is true, it will only rebuild the master free
267 // list. It is called after a Full GC (free_list_only == false) or
268 // after heap shrinking (free_list_only == true).
269 void rebuild_region_sets(bool free_list_only);
271 // The sequence of all heap regions in the heap.
272 HeapRegionSeq _hrs;
274 // Alloc region used to satisfy mutator allocation requests.
275 MutatorAllocRegion _mutator_alloc_region;
277 // Alloc region used to satisfy allocation requests by the GC for
278 // survivor objects.
279 SurvivorGCAllocRegion _survivor_gc_alloc_region;
281 // Alloc region used to satisfy allocation requests by the GC for
282 // old objects.
283 OldGCAllocRegion _old_gc_alloc_region;
285 // The last old region we allocated to during the last GC.
286 // Typically, it is not full so we should re-use it during the next GC.
287 HeapRegion* _retained_old_gc_alloc_region;
289 // It specifies whether we should attempt to expand the heap after a
290 // region allocation failure. If heap expansion fails we set this to
291 // false so that we don't re-attempt the heap expansion (it's likely
292 // that subsequent expansion attempts will also fail if one fails).
293 // Currently, it is only consulted during GC and it's reset at the
294 // start of each GC.
295 bool _expand_heap_after_alloc_failure;
297 // It resets the mutator alloc region before new allocations can take place.
298 void init_mutator_alloc_region();
300 // It releases the mutator alloc region.
301 void release_mutator_alloc_region();
303 // It initializes the GC alloc regions at the start of a GC.
304 void init_gc_alloc_regions();
306 // It releases the GC alloc regions at the end of a GC.
307 void release_gc_alloc_regions();
309 // It does any cleanup that needs to be done on the GC alloc regions
310 // before a Full GC.
311 void abandon_gc_alloc_regions();
313 // Helper for monitoring and management support.
314 G1MonitoringSupport* _g1mm;
316 // Determines PLAB size for a particular allocation purpose.
317 static size_t desired_plab_sz(GCAllocPurpose purpose);
319 // Outside of GC pauses, the number of bytes used in all regions other
320 // than the current allocation region.
321 size_t _summary_bytes_used;
323 // This is used for a quick test on whether a reference points into
324 // the collection set or not. Basically, we have an array, with one
325 // byte per region, and that byte denotes whether the corresponding
326 // region is in the collection set or not. The entry corresponding
327 // the bottom of the heap, i.e., region 0, is pointed to by
328 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
329 // biased so that it actually points to address 0 of the address
330 // space, to make the test as fast as possible (we can simply shift
331 // the address to address into it, instead of having to subtract the
332 // bottom of the heap from the address before shifting it; basically
333 // it works in the same way the card table works).
334 bool* _in_cset_fast_test;
336 // The allocated array used for the fast test on whether a reference
337 // points into the collection set or not. This field is also used to
338 // free the array.
339 bool* _in_cset_fast_test_base;
341 // The length of the _in_cset_fast_test_base array.
342 uint _in_cset_fast_test_length;
344 volatile unsigned _gc_time_stamp;
346 size_t* _surviving_young_words;
348 G1HRPrinter _hr_printer;
350 void setup_surviving_young_words();
351 void update_surviving_young_words(size_t* surv_young_words);
352 void cleanup_surviving_young_words();
354 // It decides whether an explicit GC should start a concurrent cycle
355 // instead of doing a STW GC. Currently, a concurrent cycle is
356 // explicitly started if:
357 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
358 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
359 // (c) cause == _g1_humongous_allocation
360 bool should_do_concurrent_full_gc(GCCause::Cause cause);
362 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
363 // concurrent cycles) we have started.
364 volatile unsigned int _old_marking_cycles_started;
366 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
367 // concurrent cycles) we have completed.
368 volatile unsigned int _old_marking_cycles_completed;
370 // This is a non-product method that is helpful for testing. It is
371 // called at the end of a GC and artificially expands the heap by
372 // allocating a number of dead regions. This way we can induce very
373 // frequent marking cycles and stress the cleanup / concurrent
374 // cleanup code more (as all the regions that will be allocated by
375 // this method will be found dead by the marking cycle).
376 void allocate_dummy_regions() PRODUCT_RETURN;
378 // Clear RSets after a compaction. It also resets the GC time stamps.
379 void clear_rsets_post_compaction();
381 // If the HR printer is active, dump the state of the regions in the
382 // heap after a compaction.
383 void print_hrs_post_compaction();
385 // These are macros so that, if the assert fires, we get the correct
386 // line number, file, etc.
388 #define heap_locking_asserts_err_msg(_extra_message_) \
389 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
390 (_extra_message_), \
391 BOOL_TO_STR(Heap_lock->owned_by_self()), \
392 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
393 BOOL_TO_STR(Thread::current()->is_VM_thread()))
395 #define assert_heap_locked() \
396 do { \
397 assert(Heap_lock->owned_by_self(), \
398 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
399 } while (0)
401 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
402 do { \
403 assert(Heap_lock->owned_by_self() || \
404 (SafepointSynchronize::is_at_safepoint() && \
405 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
406 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
407 "should be at a safepoint")); \
408 } while (0)
410 #define assert_heap_locked_and_not_at_safepoint() \
411 do { \
412 assert(Heap_lock->owned_by_self() && \
413 !SafepointSynchronize::is_at_safepoint(), \
414 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
415 "should not be at a safepoint")); \
416 } while (0)
418 #define assert_heap_not_locked() \
419 do { \
420 assert(!Heap_lock->owned_by_self(), \
421 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
422 } while (0)
424 #define assert_heap_not_locked_and_not_at_safepoint() \
425 do { \
426 assert(!Heap_lock->owned_by_self() && \
427 !SafepointSynchronize::is_at_safepoint(), \
428 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
429 "should not be at a safepoint")); \
430 } while (0)
432 #define assert_at_safepoint(_should_be_vm_thread_) \
433 do { \
434 assert(SafepointSynchronize::is_at_safepoint() && \
435 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
436 heap_locking_asserts_err_msg("should be at a safepoint")); \
437 } while (0)
439 #define assert_not_at_safepoint() \
440 do { \
441 assert(!SafepointSynchronize::is_at_safepoint(), \
442 heap_locking_asserts_err_msg("should not be at a safepoint")); \
443 } while (0)
445 protected:
447 // The young region list.
448 YoungList* _young_list;
450 // The current policy object for the collector.
451 G1CollectorPolicy* _g1_policy;
453 // This is the second level of trying to allocate a new region. If
454 // new_region() didn't find a region on the free_list, this call will
455 // check whether there's anything available on the
456 // secondary_free_list and/or wait for more regions to appear on
457 // that list, if _free_regions_coming is set.
458 HeapRegion* new_region_try_secondary_free_list();
460 // Try to allocate a single non-humongous HeapRegion sufficient for
461 // an allocation of the given word_size. If do_expand is true,
462 // attempt to expand the heap if necessary to satisfy the allocation
463 // request.
464 HeapRegion* new_region(size_t word_size, bool do_expand);
466 // Attempt to satisfy a humongous allocation request of the given
467 // size by finding a contiguous set of free regions of num_regions
468 // length and remove them from the master free list. Return the
469 // index of the first region or G1_NULL_HRS_INDEX if the search
470 // was unsuccessful.
471 uint humongous_obj_allocate_find_first(uint num_regions,
472 size_t word_size);
474 // Initialize a contiguous set of free regions of length num_regions
475 // and starting at index first so that they appear as a single
476 // humongous region.
477 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
478 uint num_regions,
479 size_t word_size);
481 // Attempt to allocate a humongous object of the given size. Return
482 // NULL if unsuccessful.
483 HeapWord* humongous_obj_allocate(size_t word_size);
485 // The following two methods, allocate_new_tlab() and
486 // mem_allocate(), are the two main entry points from the runtime
487 // into the G1's allocation routines. They have the following
488 // assumptions:
489 //
490 // * They should both be called outside safepoints.
491 //
492 // * They should both be called without holding the Heap_lock.
493 //
494 // * All allocation requests for new TLABs should go to
495 // allocate_new_tlab().
496 //
497 // * All non-TLAB allocation requests should go to mem_allocate().
498 //
499 // * If either call cannot satisfy the allocation request using the
500 // current allocating region, they will try to get a new one. If
501 // this fails, they will attempt to do an evacuation pause and
502 // retry the allocation.
503 //
504 // * If all allocation attempts fail, even after trying to schedule
505 // an evacuation pause, allocate_new_tlab() will return NULL,
506 // whereas mem_allocate() will attempt a heap expansion and/or
507 // schedule a Full GC.
508 //
509 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
510 // should never be called with word_size being humongous. All
511 // humongous allocation requests should go to mem_allocate() which
512 // will satisfy them with a special path.
514 virtual HeapWord* allocate_new_tlab(size_t word_size);
516 virtual HeapWord* mem_allocate(size_t word_size,
517 bool* gc_overhead_limit_was_exceeded);
519 // The following three methods take a gc_count_before_ret
520 // parameter which is used to return the GC count if the method
521 // returns NULL. Given that we are required to read the GC count
522 // while holding the Heap_lock, and these paths will take the
523 // Heap_lock at some point, it's easier to get them to read the GC
524 // count while holding the Heap_lock before they return NULL instead
525 // of the caller (namely: mem_allocate()) having to also take the
526 // Heap_lock just to read the GC count.
528 // First-level mutator allocation attempt: try to allocate out of
529 // the mutator alloc region without taking the Heap_lock. This
530 // should only be used for non-humongous allocations.
531 inline HeapWord* attempt_allocation(size_t word_size,
532 unsigned int* gc_count_before_ret);
534 // Second-level mutator allocation attempt: take the Heap_lock and
535 // retry the allocation attempt, potentially scheduling a GC
536 // pause. This should only be used for non-humongous allocations.
537 HeapWord* attempt_allocation_slow(size_t word_size,
538 unsigned int* gc_count_before_ret);
540 // Takes the Heap_lock and attempts a humongous allocation. It can
541 // potentially schedule a GC pause.
542 HeapWord* attempt_allocation_humongous(size_t word_size,
543 unsigned int* gc_count_before_ret);
545 // Allocation attempt that should be called during safepoints (e.g.,
546 // at the end of a successful GC). expect_null_mutator_alloc_region
547 // specifies whether the mutator alloc region is expected to be NULL
548 // or not.
549 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
550 bool expect_null_mutator_alloc_region);
552 // It dirties the cards that cover the block so that so that the post
553 // write barrier never queues anything when updating objects on this
554 // block. It is assumed (and in fact we assert) that the block
555 // belongs to a young region.
556 inline void dirty_young_block(HeapWord* start, size_t word_size);
558 // Allocate blocks during garbage collection. Will ensure an
559 // allocation region, either by picking one or expanding the
560 // heap, and then allocate a block of the given size. The block
561 // may not be a humongous - it must fit into a single heap region.
562 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
564 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
565 HeapRegion* alloc_region,
566 bool par,
567 size_t word_size);
569 // Ensure that no further allocations can happen in "r", bearing in mind
570 // that parallel threads might be attempting allocations.
571 void par_allocate_remaining_space(HeapRegion* r);
573 // Allocation attempt during GC for a survivor object / PLAB.
574 inline HeapWord* survivor_attempt_allocation(size_t word_size);
576 // Allocation attempt during GC for an old object / PLAB.
577 inline HeapWord* old_attempt_allocation(size_t word_size);
579 // These methods are the "callbacks" from the G1AllocRegion class.
581 // For mutator alloc regions.
582 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
583 void retire_mutator_alloc_region(HeapRegion* alloc_region,
584 size_t allocated_bytes);
586 // For GC alloc regions.
587 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
588 GCAllocPurpose ap);
589 void retire_gc_alloc_region(HeapRegion* alloc_region,
590 size_t allocated_bytes, GCAllocPurpose ap);
592 // - if explicit_gc is true, the GC is for a System.gc() or a heap
593 // inspection request and should collect the entire heap
594 // - if clear_all_soft_refs is true, all soft references should be
595 // cleared during the GC
596 // - if explicit_gc is false, word_size describes the allocation that
597 // the GC should attempt (at least) to satisfy
598 // - it returns false if it is unable to do the collection due to the
599 // GC locker being active, true otherwise
600 bool do_collection(bool explicit_gc,
601 bool clear_all_soft_refs,
602 size_t word_size);
604 // Callback from VM_G1CollectFull operation.
605 // Perform a full collection.
606 void do_full_collection(bool clear_all_soft_refs);
608 // Resize the heap if necessary after a full collection. If this is
609 // after a collect-for allocation, "word_size" is the allocation size,
610 // and will be considered part of the used portion of the heap.
611 void resize_if_necessary_after_full_collection(size_t word_size);
613 // Callback from VM_G1CollectForAllocation operation.
614 // This function does everything necessary/possible to satisfy a
615 // failed allocation request (including collection, expansion, etc.)
616 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
618 // Attempting to expand the heap sufficiently
619 // to support an allocation of the given "word_size". If
620 // successful, perform the allocation and return the address of the
621 // allocated block, or else "NULL".
622 HeapWord* expand_and_allocate(size_t word_size);
624 // Process any reference objects discovered during
625 // an incremental evacuation pause.
626 void process_discovered_references();
628 // Enqueue any remaining discovered references
629 // after processing.
630 void enqueue_discovered_references();
632 public:
634 G1MonitoringSupport* g1mm() {
635 assert(_g1mm != NULL, "should have been initialized");
636 return _g1mm;
637 }
639 // Expand the garbage-first heap by at least the given size (in bytes!).
640 // Returns true if the heap was expanded by the requested amount;
641 // false otherwise.
642 // (Rounds up to a HeapRegion boundary.)
643 bool expand(size_t expand_bytes);
645 // Do anything common to GC's.
646 virtual void gc_prologue(bool full);
647 virtual void gc_epilogue(bool full);
649 // We register a region with the fast "in collection set" test. We
650 // simply set to true the array slot corresponding to this region.
651 void register_region_with_in_cset_fast_test(HeapRegion* r) {
652 assert(_in_cset_fast_test_base != NULL, "sanity");
653 assert(r->in_collection_set(), "invariant");
654 uint index = r->hrs_index();
655 assert(index < _in_cset_fast_test_length, "invariant");
656 assert(!_in_cset_fast_test_base[index], "invariant");
657 _in_cset_fast_test_base[index] = true;
658 }
660 // This is a fast test on whether a reference points into the
661 // collection set or not. It does not assume that the reference
662 // points into the heap; if it doesn't, it will return false.
663 bool in_cset_fast_test(oop obj) {
664 assert(_in_cset_fast_test != NULL, "sanity");
665 if (_g1_committed.contains((HeapWord*) obj)) {
666 // no need to subtract the bottom of the heap from obj,
667 // _in_cset_fast_test is biased
668 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
669 bool ret = _in_cset_fast_test[index];
670 // let's make sure the result is consistent with what the slower
671 // test returns
672 assert( ret || !obj_in_cs(obj), "sanity");
673 assert(!ret || obj_in_cs(obj), "sanity");
674 return ret;
675 } else {
676 return false;
677 }
678 }
680 void clear_cset_fast_test() {
681 assert(_in_cset_fast_test_base != NULL, "sanity");
682 memset(_in_cset_fast_test_base, false,
683 (size_t) _in_cset_fast_test_length * sizeof(bool));
684 }
686 // This is called at the start of either a concurrent cycle or a Full
687 // GC to update the number of old marking cycles started.
688 void increment_old_marking_cycles_started();
690 // This is called at the end of either a concurrent cycle or a Full
691 // GC to update the number of old marking cycles completed. Those two
692 // can happen in a nested fashion, i.e., we start a concurrent
693 // cycle, a Full GC happens half-way through it which ends first,
694 // and then the cycle notices that a Full GC happened and ends
695 // too. The concurrent parameter is a boolean to help us do a bit
696 // tighter consistency checking in the method. If concurrent is
697 // false, the caller is the inner caller in the nesting (i.e., the
698 // Full GC). If concurrent is true, the caller is the outer caller
699 // in this nesting (i.e., the concurrent cycle). Further nesting is
700 // not currently supported. The end of this call also notifies
701 // the FullGCCount_lock in case a Java thread is waiting for a full
702 // GC to happen (e.g., it called System.gc() with
703 // +ExplicitGCInvokesConcurrent).
704 void increment_old_marking_cycles_completed(bool concurrent);
706 unsigned int old_marking_cycles_completed() {
707 return _old_marking_cycles_completed;
708 }
710 G1HRPrinter* hr_printer() { return &_hr_printer; }
712 protected:
714 // Shrink the garbage-first heap by at most the given size (in bytes!).
715 // (Rounds down to a HeapRegion boundary.)
716 virtual void shrink(size_t expand_bytes);
717 void shrink_helper(size_t expand_bytes);
719 #if TASKQUEUE_STATS
720 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
721 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
722 void reset_taskqueue_stats();
723 #endif // TASKQUEUE_STATS
725 // Schedule the VM operation that will do an evacuation pause to
726 // satisfy an allocation request of word_size. *succeeded will
727 // return whether the VM operation was successful (it did do an
728 // evacuation pause) or not (another thread beat us to it or the GC
729 // locker was active). Given that we should not be holding the
730 // Heap_lock when we enter this method, we will pass the
731 // gc_count_before (i.e., total_collections()) as a parameter since
732 // it has to be read while holding the Heap_lock. Currently, both
733 // methods that call do_collection_pause() release the Heap_lock
734 // before the call, so it's easy to read gc_count_before just before.
735 HeapWord* do_collection_pause(size_t word_size,
736 unsigned int gc_count_before,
737 bool* succeeded);
739 // The guts of the incremental collection pause, executed by the vm
740 // thread. It returns false if it is unable to do the collection due
741 // to the GC locker being active, true otherwise
742 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
744 // Actually do the work of evacuating the collection set.
745 void evacuate_collection_set();
747 // The g1 remembered set of the heap.
748 G1RemSet* _g1_rem_set;
749 // And it's mod ref barrier set, used to track updates for the above.
750 ModRefBarrierSet* _mr_bs;
752 // A set of cards that cover the objects for which the Rsets should be updated
753 // concurrently after the collection.
754 DirtyCardQueueSet _dirty_card_queue_set;
756 // The Heap Region Rem Set Iterator.
757 HeapRegionRemSetIterator** _rem_set_iterator;
759 // The closure used to refine a single card.
760 RefineCardTableEntryClosure* _refine_cte_cl;
762 // A function to check the consistency of dirty card logs.
763 void check_ct_logs_at_safepoint();
765 // A DirtyCardQueueSet that is used to hold cards that contain
766 // references into the current collection set. This is used to
767 // update the remembered sets of the regions in the collection
768 // set in the event of an evacuation failure.
769 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
771 // After a collection pause, make the regions in the CS into free
772 // regions.
773 void free_collection_set(HeapRegion* cs_head);
775 // Abandon the current collection set without recording policy
776 // statistics or updating free lists.
777 void abandon_collection_set(HeapRegion* cs_head);
779 // Applies "scan_non_heap_roots" to roots outside the heap,
780 // "scan_rs" to roots inside the heap (having done "set_region" to
781 // indicate the region in which the root resides), and does "scan_perm"
782 // (setting the generation to the perm generation.) If "scan_rs" is
783 // NULL, then this step is skipped. The "worker_i"
784 // param is for use with parallel roots processing, and should be
785 // the "i" of the calling parallel worker thread's work(i) function.
786 // In the sequential case this param will be ignored.
787 void g1_process_strong_roots(bool collecting_perm_gen,
788 ScanningOption so,
789 OopClosure* scan_non_heap_roots,
790 OopsInHeapRegionClosure* scan_rs,
791 OopsInGenClosure* scan_perm,
792 int worker_i);
794 // Apply "blk" to all the weak roots of the system. These include
795 // JNI weak roots, the code cache, system dictionary, symbol table,
796 // string table, and referents of reachable weak refs.
797 void g1_process_weak_roots(OopClosure* root_closure,
798 OopClosure* non_root_closure);
800 // Frees a non-humongous region by initializing its contents and
801 // adding it to the free list that's passed as a parameter (this is
802 // usually a local list which will be appended to the master free
803 // list later). The used bytes of freed regions are accumulated in
804 // pre_used. If par is true, the region's RSet will not be freed
805 // up. The assumption is that this will be done later.
806 void free_region(HeapRegion* hr,
807 size_t* pre_used,
808 FreeRegionList* free_list,
809 bool par);
811 // Frees a humongous region by collapsing it into individual regions
812 // and calling free_region() for each of them. The freed regions
813 // will be added to the free list that's passed as a parameter (this
814 // is usually a local list which will be appended to the master free
815 // list later). The used bytes of freed regions are accumulated in
816 // pre_used. If par is true, the region's RSet will not be freed
817 // up. The assumption is that this will be done later.
818 void free_humongous_region(HeapRegion* hr,
819 size_t* pre_used,
820 FreeRegionList* free_list,
821 HumongousRegionSet* humongous_proxy_set,
822 bool par);
824 // Notifies all the necessary spaces that the committed space has
825 // been updated (either expanded or shrunk). It should be called
826 // after _g1_storage is updated.
827 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
829 // The concurrent marker (and the thread it runs in.)
830 ConcurrentMark* _cm;
831 ConcurrentMarkThread* _cmThread;
832 bool _mark_in_progress;
834 // The concurrent refiner.
835 ConcurrentG1Refine* _cg1r;
837 // The parallel task queues
838 RefToScanQueueSet *_task_queues;
840 // True iff a evacuation has failed in the current collection.
841 bool _evacuation_failed;
843 // Set the attribute indicating whether evacuation has failed in the
844 // current collection.
845 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
847 // Failed evacuations cause some logical from-space objects to have
848 // forwarding pointers to themselves. Reset them.
849 void remove_self_forwarding_pointers();
851 // When one is non-null, so is the other. Together, they each pair is
852 // an object with a preserved mark, and its mark value.
853 GrowableArray<oop>* _objs_with_preserved_marks;
854 GrowableArray<markOop>* _preserved_marks_of_objs;
856 // Preserve the mark of "obj", if necessary, in preparation for its mark
857 // word being overwritten with a self-forwarding-pointer.
858 void preserve_mark_if_necessary(oop obj, markOop m);
860 // The stack of evac-failure objects left to be scanned.
861 GrowableArray<oop>* _evac_failure_scan_stack;
862 // The closure to apply to evac-failure objects.
864 OopsInHeapRegionClosure* _evac_failure_closure;
865 // Set the field above.
866 void
867 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
868 _evac_failure_closure = evac_failure_closure;
869 }
871 // Push "obj" on the scan stack.
872 void push_on_evac_failure_scan_stack(oop obj);
873 // Process scan stack entries until the stack is empty.
874 void drain_evac_failure_scan_stack();
875 // True iff an invocation of "drain_scan_stack" is in progress; to
876 // prevent unnecessary recursion.
877 bool _drain_in_progress;
879 // Do any necessary initialization for evacuation-failure handling.
880 // "cl" is the closure that will be used to process evac-failure
881 // objects.
882 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
883 // Do any necessary cleanup for evacuation-failure handling data
884 // structures.
885 void finalize_for_evac_failure();
887 // An attempt to evacuate "obj" has failed; take necessary steps.
888 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
889 void handle_evacuation_failure_common(oop obj, markOop m);
891 // ("Weak") Reference processing support.
892 //
893 // G1 has 2 instances of the referece processor class. One
894 // (_ref_processor_cm) handles reference object discovery
895 // and subsequent processing during concurrent marking cycles.
896 //
897 // The other (_ref_processor_stw) handles reference object
898 // discovery and processing during full GCs and incremental
899 // evacuation pauses.
900 //
901 // During an incremental pause, reference discovery will be
902 // temporarily disabled for _ref_processor_cm and will be
903 // enabled for _ref_processor_stw. At the end of the evacuation
904 // pause references discovered by _ref_processor_stw will be
905 // processed and discovery will be disabled. The previous
906 // setting for reference object discovery for _ref_processor_cm
907 // will be re-instated.
908 //
909 // At the start of marking:
910 // * Discovery by the CM ref processor is verified to be inactive
911 // and it's discovered lists are empty.
912 // * Discovery by the CM ref processor is then enabled.
913 //
914 // At the end of marking:
915 // * Any references on the CM ref processor's discovered
916 // lists are processed (possibly MT).
917 //
918 // At the start of full GC we:
919 // * Disable discovery by the CM ref processor and
920 // empty CM ref processor's discovered lists
921 // (without processing any entries).
922 // * Verify that the STW ref processor is inactive and it's
923 // discovered lists are empty.
924 // * Temporarily set STW ref processor discovery as single threaded.
925 // * Temporarily clear the STW ref processor's _is_alive_non_header
926 // field.
927 // * Finally enable discovery by the STW ref processor.
928 //
929 // The STW ref processor is used to record any discovered
930 // references during the full GC.
931 //
932 // At the end of a full GC we:
933 // * Enqueue any reference objects discovered by the STW ref processor
934 // that have non-live referents. This has the side-effect of
935 // making the STW ref processor inactive by disabling discovery.
936 // * Verify that the CM ref processor is still inactive
937 // and no references have been placed on it's discovered
938 // lists (also checked as a precondition during initial marking).
940 // The (stw) reference processor...
941 ReferenceProcessor* _ref_processor_stw;
943 // During reference object discovery, the _is_alive_non_header
944 // closure (if non-null) is applied to the referent object to
945 // determine whether the referent is live. If so then the
946 // reference object does not need to be 'discovered' and can
947 // be treated as a regular oop. This has the benefit of reducing
948 // the number of 'discovered' reference objects that need to
949 // be processed.
950 //
951 // Instance of the is_alive closure for embedding into the
952 // STW reference processor as the _is_alive_non_header field.
953 // Supplying a value for the _is_alive_non_header field is
954 // optional but doing so prevents unnecessary additions to
955 // the discovered lists during reference discovery.
956 G1STWIsAliveClosure _is_alive_closure_stw;
958 // The (concurrent marking) reference processor...
959 ReferenceProcessor* _ref_processor_cm;
961 // Instance of the concurrent mark is_alive closure for embedding
962 // into the Concurrent Marking reference processor as the
963 // _is_alive_non_header field. Supplying a value for the
964 // _is_alive_non_header field is optional but doing so prevents
965 // unnecessary additions to the discovered lists during reference
966 // discovery.
967 G1CMIsAliveClosure _is_alive_closure_cm;
969 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
970 HeapRegion** _worker_cset_start_region;
972 // Time stamp to validate the regions recorded in the cache
973 // used by G1CollectedHeap::start_cset_region_for_worker().
974 // The heap region entry for a given worker is valid iff
975 // the associated time stamp value matches the current value
976 // of G1CollectedHeap::_gc_time_stamp.
977 unsigned int* _worker_cset_start_region_time_stamp;
979 enum G1H_process_strong_roots_tasks {
980 G1H_PS_filter_satb_buffers,
981 G1H_PS_refProcessor_oops_do,
982 // Leave this one last.
983 G1H_PS_NumElements
984 };
986 SubTasksDone* _process_strong_tasks;
988 volatile bool _free_regions_coming;
990 public:
992 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
994 void set_refine_cte_cl_concurrency(bool concurrent);
996 RefToScanQueue *task_queue(int i) const;
998 // A set of cards where updates happened during the GC
999 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1001 // A DirtyCardQueueSet that is used to hold cards that contain
1002 // references into the current collection set. This is used to
1003 // update the remembered sets of the regions in the collection
1004 // set in the event of an evacuation failure.
1005 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1006 { return _into_cset_dirty_card_queue_set; }
1008 // Create a G1CollectedHeap with the specified policy.
1009 // Must call the initialize method afterwards.
1010 // May not return if something goes wrong.
1011 G1CollectedHeap(G1CollectorPolicy* policy);
1013 // Initialize the G1CollectedHeap to have the initial and
1014 // maximum sizes, permanent generation, and remembered and barrier sets
1015 // specified by the policy object.
1016 jint initialize();
1018 // Initialize weak reference processing.
1019 virtual void ref_processing_init();
1021 void set_par_threads(uint t) {
1022 SharedHeap::set_par_threads(t);
1023 // Done in SharedHeap but oddly there are
1024 // two _process_strong_tasks's in a G1CollectedHeap
1025 // so do it here too.
1026 _process_strong_tasks->set_n_threads(t);
1027 }
1029 // Set _n_par_threads according to a policy TBD.
1030 void set_par_threads();
1032 void set_n_termination(int t) {
1033 _process_strong_tasks->set_n_threads(t);
1034 }
1036 virtual CollectedHeap::Name kind() const {
1037 return CollectedHeap::G1CollectedHeap;
1038 }
1040 // The current policy object for the collector.
1041 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1043 // Adaptive size policy. No such thing for g1.
1044 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1046 // The rem set and barrier set.
1047 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1048 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1050 // The rem set iterator.
1051 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1052 return _rem_set_iterator[i];
1053 }
1055 HeapRegionRemSetIterator* rem_set_iterator() {
1056 return _rem_set_iterator[0];
1057 }
1059 unsigned get_gc_time_stamp() {
1060 return _gc_time_stamp;
1061 }
1063 void reset_gc_time_stamp() {
1064 _gc_time_stamp = 0;
1065 OrderAccess::fence();
1066 // Clear the cached CSet starting regions and time stamps.
1067 // Their validity is dependent on the GC timestamp.
1068 clear_cset_start_regions();
1069 }
1071 void check_gc_time_stamps() PRODUCT_RETURN;
1073 void increment_gc_time_stamp() {
1074 ++_gc_time_stamp;
1075 OrderAccess::fence();
1076 }
1078 // Reset the given region's GC timestamp. If it's starts humongous,
1079 // also reset the GC timestamp of its corresponding
1080 // continues humongous regions too.
1081 void reset_gc_time_stamps(HeapRegion* hr);
1083 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1084 DirtyCardQueue* into_cset_dcq,
1085 bool concurrent, int worker_i);
1087 // The shared block offset table array.
1088 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1090 // Reference Processing accessors
1092 // The STW reference processor....
1093 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1095 // The Concurent Marking reference processor...
1096 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1098 virtual size_t capacity() const;
1099 virtual size_t used() const;
1100 // This should be called when we're not holding the heap lock. The
1101 // result might be a bit inaccurate.
1102 size_t used_unlocked() const;
1103 size_t recalculate_used() const;
1105 // These virtual functions do the actual allocation.
1106 // Some heaps may offer a contiguous region for shared non-blocking
1107 // allocation, via inlined code (by exporting the address of the top and
1108 // end fields defining the extent of the contiguous allocation region.)
1109 // But G1CollectedHeap doesn't yet support this.
1111 // Return an estimate of the maximum allocation that could be performed
1112 // without triggering any collection or expansion activity. In a
1113 // generational collector, for example, this is probably the largest
1114 // allocation that could be supported (without expansion) in the youngest
1115 // generation. It is "unsafe" because no locks are taken; the result
1116 // should be treated as an approximation, not a guarantee, for use in
1117 // heuristic resizing decisions.
1118 virtual size_t unsafe_max_alloc();
1120 virtual bool is_maximal_no_gc() const {
1121 return _g1_storage.uncommitted_size() == 0;
1122 }
1124 // The total number of regions in the heap.
1125 uint n_regions() { return _hrs.length(); }
1127 // The max number of regions in the heap.
1128 uint max_regions() { return _hrs.max_length(); }
1130 // The number of regions that are completely free.
1131 uint free_regions() { return _free_list.length(); }
1133 // The number of regions that are not completely free.
1134 uint used_regions() { return n_regions() - free_regions(); }
1136 // The number of regions available for "regular" expansion.
1137 uint expansion_regions() { return _expansion_regions; }
1139 // Factory method for HeapRegion instances. It will return NULL if
1140 // the allocation fails.
1141 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1143 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1144 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1145 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1146 void verify_dirty_young_regions() PRODUCT_RETURN;
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();
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 definning 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
1164 #ifdef ASSERT
1165 bool is_on_master_free_list(HeapRegion* hr) {
1166 return hr->containing_set() == &_free_list;
1167 }
1169 bool is_in_humongous_set(HeapRegion* hr) {
1170 return hr->containing_set() == &_humongous_set;
1171 }
1172 #endif // ASSERT
1174 // Wrapper for the region list operations that can be called from
1175 // methods outside this class.
1177 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1178 _secondary_free_list.add_as_tail(list);
1179 }
1181 void append_secondary_free_list() {
1182 _free_list.add_as_head(&_secondary_free_list);
1183 }
1185 void append_secondary_free_list_if_not_empty_with_lock() {
1186 // If the secondary free list looks empty there's no reason to
1187 // take the lock and then try to append it.
1188 if (!_secondary_free_list.is_empty()) {
1189 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1190 append_secondary_free_list();
1191 }
1192 }
1194 void old_set_remove(HeapRegion* hr) {
1195 _old_set.remove(hr);
1196 }
1198 size_t non_young_capacity_bytes() {
1199 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1200 }
1202 void set_free_regions_coming();
1203 void reset_free_regions_coming();
1204 bool free_regions_coming() { return _free_regions_coming; }
1205 void wait_while_free_regions_coming();
1207 // Determine whether the given region is one that we are using as an
1208 // old GC alloc region.
1209 bool is_old_gc_alloc_region(HeapRegion* hr) {
1210 return hr == _retained_old_gc_alloc_region;
1211 }
1213 // Perform a collection of the heap; intended for use in implementing
1214 // "System.gc". This probably implies as full a collection as the
1215 // "CollectedHeap" supports.
1216 virtual void collect(GCCause::Cause cause);
1218 // The same as above but assume that the caller holds the Heap_lock.
1219 void collect_locked(GCCause::Cause cause);
1221 // This interface assumes that it's being called by the
1222 // vm thread. It collects the heap assuming that the
1223 // heap lock is already held and that we are executing in
1224 // the context of the vm thread.
1225 virtual void collect_as_vm_thread(GCCause::Cause cause);
1227 // True iff a evacuation has failed in the most-recent collection.
1228 bool evacuation_failed() { return _evacuation_failed; }
1230 // It will free a region if it has allocated objects in it that are
1231 // all dead. It calls either free_region() or
1232 // free_humongous_region() depending on the type of the region that
1233 // is passed to it.
1234 void free_region_if_empty(HeapRegion* hr,
1235 size_t* pre_used,
1236 FreeRegionList* free_list,
1237 OldRegionSet* old_proxy_set,
1238 HumongousRegionSet* humongous_proxy_set,
1239 HRRSCleanupTask* hrrs_cleanup_task,
1240 bool par);
1242 // It appends the free list to the master free list and updates the
1243 // master humongous list according to the contents of the proxy
1244 // list. It also adjusts the total used bytes according to pre_used
1245 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1246 void update_sets_after_freeing_regions(size_t pre_used,
1247 FreeRegionList* free_list,
1248 OldRegionSet* old_proxy_set,
1249 HumongousRegionSet* humongous_proxy_set,
1250 bool par);
1252 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1253 virtual bool is_in(const void* p) const;
1255 // Return "TRUE" iff the given object address is within the collection
1256 // set.
1257 inline bool obj_in_cs(oop obj);
1259 // Return "TRUE" iff the given object address is in the reserved
1260 // region of g1 (excluding the permanent generation).
1261 bool is_in_g1_reserved(const void* p) const {
1262 return _g1_reserved.contains(p);
1263 }
1265 // Returns a MemRegion that corresponds to the space that has been
1266 // reserved for the heap
1267 MemRegion g1_reserved() {
1268 return _g1_reserved;
1269 }
1271 // Returns a MemRegion that corresponds to the space that has been
1272 // committed in the heap
1273 MemRegion g1_committed() {
1274 return _g1_committed;
1275 }
1277 virtual bool is_in_closed_subset(const void* p) const;
1279 // This resets the card table to all zeros. It is used after
1280 // a collection pause which used the card table to claim cards.
1281 void cleanUpCardTable();
1283 // Iteration functions.
1285 // Iterate over all the ref-containing fields of all objects, calling
1286 // "cl.do_oop" on each.
1287 virtual void oop_iterate(OopClosure* cl) {
1288 oop_iterate(cl, true);
1289 }
1290 void oop_iterate(OopClosure* cl, bool do_perm);
1292 // Same as above, restricted to a memory region.
1293 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1294 oop_iterate(mr, cl, true);
1295 }
1296 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1298 // Iterate over all objects, calling "cl.do_object" on each.
1299 virtual void object_iterate(ObjectClosure* cl) {
1300 object_iterate(cl, true);
1301 }
1302 virtual void safe_object_iterate(ObjectClosure* cl) {
1303 object_iterate(cl, true);
1304 }
1305 void object_iterate(ObjectClosure* cl, bool do_perm);
1307 // Iterate over all objects allocated since the last collection, calling
1308 // "cl.do_object" on each. The heap must have been initialized properly
1309 // to support this function, or else this call will fail.
1310 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1312 // Iterate over all spaces in use in the heap, in ascending address order.
1313 virtual void space_iterate(SpaceClosure* cl);
1315 // Iterate over heap regions, in address order, terminating the
1316 // iteration early if the "doHeapRegion" method returns "true".
1317 void heap_region_iterate(HeapRegionClosure* blk) const;
1319 // Return the region with the given index. It assumes the index is valid.
1320 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1322 // Divide the heap region sequence into "chunks" of some size (the number
1323 // of regions divided by the number of parallel threads times some
1324 // overpartition factor, currently 4). Assumes that this will be called
1325 // in parallel by ParallelGCThreads worker threads with discinct worker
1326 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1327 // calls will use the same "claim_value", and that that claim value is
1328 // different from the claim_value of any heap region before the start of
1329 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1330 // attempting to claim the first region in each chunk, and, if
1331 // successful, applying the closure to each region in the chunk (and
1332 // setting the claim value of the second and subsequent regions of the
1333 // chunk.) For now requires that "doHeapRegion" always returns "false",
1334 // i.e., that a closure never attempt to abort a traversal.
1335 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1336 uint worker,
1337 uint no_of_par_workers,
1338 jint claim_value);
1340 // It resets all the region claim values to the default.
1341 void reset_heap_region_claim_values();
1343 // Resets the claim values of regions in the current
1344 // collection set to the default.
1345 void reset_cset_heap_region_claim_values();
1347 #ifdef ASSERT
1348 bool check_heap_region_claim_values(jint claim_value);
1350 // Same as the routine above but only checks regions in the
1351 // current collection set.
1352 bool check_cset_heap_region_claim_values(jint claim_value);
1353 #endif // ASSERT
1355 // Clear the cached cset start regions and (more importantly)
1356 // the time stamps. Called when we reset the GC time stamp.
1357 void clear_cset_start_regions();
1359 // Given the id of a worker, obtain or calculate a suitable
1360 // starting region for iterating over the current collection set.
1361 HeapRegion* start_cset_region_for_worker(int worker_i);
1363 // This is a convenience method that is used by the
1364 // HeapRegionIterator classes to calculate the starting region for
1365 // each worker so that they do not all start from the same region.
1366 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1368 // Iterate over the regions (if any) in the current collection set.
1369 void collection_set_iterate(HeapRegionClosure* blk);
1371 // As above but starting from region r
1372 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1374 // Returns the first (lowest address) compactible space in the heap.
1375 virtual CompactibleSpace* first_compactible_space();
1377 // A CollectedHeap will contain some number of spaces. This finds the
1378 // space containing a given address, or else returns NULL.
1379 virtual Space* space_containing(const void* addr) const;
1381 // A G1CollectedHeap will contain some number of heap regions. This
1382 // finds the region containing a given address, or else returns NULL.
1383 template <class T>
1384 inline HeapRegion* heap_region_containing(const T addr) const;
1386 // Like the above, but requires "addr" to be in the heap (to avoid a
1387 // null-check), and unlike the above, may return an continuing humongous
1388 // region.
1389 template <class T>
1390 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1392 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1393 // each address in the (reserved) heap is a member of exactly
1394 // one block. The defining characteristic of a block is that it is
1395 // possible to find its size, and thus to progress forward to the next
1396 // block. (Blocks may be of different sizes.) Thus, blocks may
1397 // represent Java objects, or they might be free blocks in a
1398 // free-list-based heap (or subheap), as long as the two kinds are
1399 // distinguishable and the size of each is determinable.
1401 // Returns the address of the start of the "block" that contains the
1402 // address "addr". We say "blocks" instead of "object" since some heaps
1403 // may not pack objects densely; a chunk may either be an object or a
1404 // non-object.
1405 virtual HeapWord* block_start(const void* addr) const;
1407 // Requires "addr" to be the start of a chunk, and returns its size.
1408 // "addr + size" is required to be the start of a new chunk, or the end
1409 // of the active area of the heap.
1410 virtual size_t block_size(const HeapWord* addr) const;
1412 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1413 // the block is an object.
1414 virtual bool block_is_obj(const HeapWord* addr) const;
1416 // Does this heap support heap inspection? (+PrintClassHistogram)
1417 virtual bool supports_heap_inspection() const { return true; }
1419 // Section on thread-local allocation buffers (TLABs)
1420 // See CollectedHeap for semantics.
1422 virtual bool supports_tlab_allocation() const;
1423 virtual size_t tlab_capacity(Thread* thr) const;
1424 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1426 // Can a compiler initialize a new object without store barriers?
1427 // This permission only extends from the creation of a new object
1428 // via a TLAB up to the first subsequent safepoint. If such permission
1429 // is granted for this heap type, the compiler promises to call
1430 // defer_store_barrier() below on any slow path allocation of
1431 // a new object for which such initializing store barriers will
1432 // have been elided. G1, like CMS, allows this, but should be
1433 // ready to provide a compensating write barrier as necessary
1434 // if that storage came out of a non-young region. The efficiency
1435 // of this implementation depends crucially on being able to
1436 // answer very efficiently in constant time whether a piece of
1437 // storage in the heap comes from a young region or not.
1438 // See ReduceInitialCardMarks.
1439 virtual bool can_elide_tlab_store_barriers() const {
1440 return true;
1441 }
1443 virtual bool card_mark_must_follow_store() const {
1444 return true;
1445 }
1447 bool is_in_young(const oop obj) {
1448 HeapRegion* hr = heap_region_containing(obj);
1449 return hr != NULL && hr->is_young();
1450 }
1452 #ifdef ASSERT
1453 virtual bool is_in_partial_collection(const void* p);
1454 #endif
1456 virtual bool is_scavengable(const void* addr);
1458 // We don't need barriers for initializing stores to objects
1459 // in the young gen: for the SATB pre-barrier, there is no
1460 // pre-value that needs to be remembered; for the remembered-set
1461 // update logging post-barrier, we don't maintain remembered set
1462 // information for young gen objects.
1463 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1464 return is_in_young(new_obj);
1465 }
1467 // Can a compiler elide a store barrier when it writes
1468 // a permanent oop into the heap? Applies when the compiler
1469 // is storing x to the heap, where x->is_perm() is true.
1470 virtual bool can_elide_permanent_oop_store_barriers() const {
1471 // At least until perm gen collection is also G1-ified, at
1472 // which point this should return false.
1473 return true;
1474 }
1476 // Returns "true" iff the given word_size is "very large".
1477 static bool isHumongous(size_t word_size) {
1478 // Note this has to be strictly greater-than as the TLABs
1479 // are capped at the humongous thresold and we want to
1480 // ensure that we don't try to allocate a TLAB as
1481 // humongous and that we don't allocate a humongous
1482 // object in a TLAB.
1483 return word_size > _humongous_object_threshold_in_words;
1484 }
1486 // Update mod union table with the set of dirty cards.
1487 void updateModUnion();
1489 // Set the mod union bits corresponding to the given memRegion. Note
1490 // that this is always a safe operation, since it doesn't clear any
1491 // bits.
1492 void markModUnionRange(MemRegion mr);
1494 // Records the fact that a marking phase is no longer in progress.
1495 void set_marking_complete() {
1496 _mark_in_progress = false;
1497 }
1498 void set_marking_started() {
1499 _mark_in_progress = true;
1500 }
1501 bool mark_in_progress() {
1502 return _mark_in_progress;
1503 }
1505 // Print the maximum heap capacity.
1506 virtual size_t max_capacity() const;
1508 virtual jlong millis_since_last_gc();
1510 // Perform any cleanup actions necessary before allowing a verification.
1511 virtual void prepare_for_verify();
1513 // Perform verification.
1515 // vo == UsePrevMarking -> use "prev" marking information,
1516 // vo == UseNextMarking -> use "next" marking information
1517 // vo == UseMarkWord -> use the mark word in the object header
1518 //
1519 // NOTE: Only the "prev" marking information is guaranteed to be
1520 // consistent most of the time, so most calls to this should use
1521 // vo == UsePrevMarking.
1522 // Currently, there is only one case where this is called with
1523 // vo == UseNextMarking, which is to verify the "next" marking
1524 // information at the end of remark.
1525 // Currently there is only one place where this is called with
1526 // vo == UseMarkWord, which is to verify the marking during a
1527 // full GC.
1528 void verify(bool silent, VerifyOption vo);
1530 // Override; it uses the "prev" marking information
1531 virtual void verify(bool silent);
1532 virtual void print_on(outputStream* st) const;
1533 virtual void print_extended_on(outputStream* st) const;
1535 virtual void print_gc_threads_on(outputStream* st) const;
1536 virtual void gc_threads_do(ThreadClosure* tc) const;
1538 // Override
1539 void print_tracing_info() const;
1541 // The following two methods are helpful for debugging RSet issues.
1542 void print_cset_rsets() PRODUCT_RETURN;
1543 void print_all_rsets() PRODUCT_RETURN;
1545 // Convenience function to be used in situations where the heap type can be
1546 // asserted to be this type.
1547 static G1CollectedHeap* heap();
1549 void set_region_short_lived_locked(HeapRegion* hr);
1550 // add appropriate methods for any other surv rate groups
1552 YoungList* young_list() { return _young_list; }
1554 // debugging
1555 bool check_young_list_well_formed() {
1556 return _young_list->check_list_well_formed();
1557 }
1559 bool check_young_list_empty(bool check_heap,
1560 bool check_sample = true);
1562 // *** Stuff related to concurrent marking. It's not clear to me that so
1563 // many of these need to be public.
1565 // The functions below are helper functions that a subclass of
1566 // "CollectedHeap" can use in the implementation of its virtual
1567 // functions.
1568 // This performs a concurrent marking of the live objects in a
1569 // bitmap off to the side.
1570 void doConcurrentMark();
1572 bool isMarkedPrev(oop obj) const;
1573 bool isMarkedNext(oop obj) const;
1575 // Determine if an object is dead, given the object and also
1576 // the region to which the object belongs. An object is dead
1577 // iff a) it was not allocated since the last mark and b) it
1578 // is not marked.
1580 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1581 return
1582 !hr->obj_allocated_since_prev_marking(obj) &&
1583 !isMarkedPrev(obj);
1584 }
1586 // This function returns true when an object has been
1587 // around since the previous marking and hasn't yet
1588 // been marked during this marking.
1590 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1591 return
1592 !hr->obj_allocated_since_next_marking(obj) &&
1593 !isMarkedNext(obj);
1594 }
1596 // Determine if an object is dead, given only the object itself.
1597 // This will find the region to which the object belongs and
1598 // then call the region version of the same function.
1600 // Added if it is in permanent gen it isn't dead.
1601 // Added if it is NULL it isn't dead.
1603 bool is_obj_dead(const oop obj) const {
1604 const HeapRegion* hr = heap_region_containing(obj);
1605 if (hr == NULL) {
1606 if (Universe::heap()->is_in_permanent(obj))
1607 return false;
1608 else if (obj == NULL) return false;
1609 else return true;
1610 }
1611 else return is_obj_dead(obj, hr);
1612 }
1614 bool is_obj_ill(const oop obj) const {
1615 const HeapRegion* hr = heap_region_containing(obj);
1616 if (hr == NULL) {
1617 if (Universe::heap()->is_in_permanent(obj))
1618 return false;
1619 else if (obj == NULL) return false;
1620 else return true;
1621 }
1622 else return is_obj_ill(obj, hr);
1623 }
1625 // The methods below are here for convenience and dispatch the
1626 // appropriate method depending on value of the given VerifyOption
1627 // parameter. The options for that parameter are:
1628 //
1629 // vo == UsePrevMarking -> use "prev" marking information,
1630 // vo == UseNextMarking -> use "next" marking information,
1631 // vo == UseMarkWord -> use mark word from object header
1633 bool is_obj_dead_cond(const oop obj,
1634 const HeapRegion* hr,
1635 const VerifyOption vo) const {
1636 switch (vo) {
1637 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1638 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1639 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1640 default: ShouldNotReachHere();
1641 }
1642 return false; // keep some compilers happy
1643 }
1645 bool is_obj_dead_cond(const oop obj,
1646 const VerifyOption vo) const {
1647 switch (vo) {
1648 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1649 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1650 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1651 default: ShouldNotReachHere();
1652 }
1653 return false; // keep some compilers happy
1654 }
1656 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1657 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1658 bool is_marked(oop obj, VerifyOption vo);
1659 const char* top_at_mark_start_str(VerifyOption vo);
1661 // The following is just to alert the verification code
1662 // that a full collection has occurred and that the
1663 // remembered sets are no longer up to date.
1664 bool _full_collection;
1665 void set_full_collection() { _full_collection = true;}
1666 void clear_full_collection() {_full_collection = false;}
1667 bool full_collection() {return _full_collection;}
1669 ConcurrentMark* concurrent_mark() const { return _cm; }
1670 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1672 // The dirty cards region list is used to record a subset of regions
1673 // whose cards need clearing. The list if populated during the
1674 // remembered set scanning and drained during the card table
1675 // cleanup. Although the methods are reentrant, population/draining
1676 // phases must not overlap. For synchronization purposes the last
1677 // element on the list points to itself.
1678 HeapRegion* _dirty_cards_region_list;
1679 void push_dirty_cards_region(HeapRegion* hr);
1680 HeapRegion* pop_dirty_cards_region();
1682 public:
1683 void stop_conc_gc_threads();
1685 size_t pending_card_num();
1686 size_t max_pending_card_num();
1687 size_t cards_scanned();
1689 protected:
1690 size_t _max_heap_capacity;
1691 };
1693 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1694 private:
1695 bool _retired;
1697 public:
1698 G1ParGCAllocBuffer(size_t gclab_word_size);
1700 void set_buf(HeapWord* buf) {
1701 ParGCAllocBuffer::set_buf(buf);
1702 _retired = false;
1703 }
1705 void retire(bool end_of_gc, bool retain) {
1706 if (_retired)
1707 return;
1708 ParGCAllocBuffer::retire(end_of_gc, retain);
1709 _retired = true;
1710 }
1711 };
1713 class G1ParScanThreadState : public StackObj {
1714 protected:
1715 G1CollectedHeap* _g1h;
1716 RefToScanQueue* _refs;
1717 DirtyCardQueue _dcq;
1718 CardTableModRefBS* _ct_bs;
1719 G1RemSet* _g1_rem;
1721 G1ParGCAllocBuffer _surviving_alloc_buffer;
1722 G1ParGCAllocBuffer _tenured_alloc_buffer;
1723 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1724 ageTable _age_table;
1726 size_t _alloc_buffer_waste;
1727 size_t _undo_waste;
1729 OopsInHeapRegionClosure* _evac_failure_cl;
1730 G1ParScanHeapEvacClosure* _evac_cl;
1731 G1ParScanPartialArrayClosure* _partial_scan_cl;
1733 int _hash_seed;
1734 uint _queue_num;
1736 size_t _term_attempts;
1738 double _start;
1739 double _start_strong_roots;
1740 double _strong_roots_time;
1741 double _start_term;
1742 double _term_time;
1744 // Map from young-age-index (0 == not young, 1 is youngest) to
1745 // surviving words. base is what we get back from the malloc call
1746 size_t* _surviving_young_words_base;
1747 // this points into the array, as we use the first few entries for padding
1748 size_t* _surviving_young_words;
1750 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1752 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1754 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1756 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1757 CardTableModRefBS* ctbs() { return _ct_bs; }
1759 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1760 if (!from->is_survivor()) {
1761 _g1_rem->par_write_ref(from, p, tid);
1762 }
1763 }
1765 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1766 // If the new value of the field points to the same region or
1767 // is the to-space, we don't need to include it in the Rset updates.
1768 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1769 size_t card_index = ctbs()->index_for(p);
1770 // If the card hasn't been added to the buffer, do it.
1771 if (ctbs()->mark_card_deferred(card_index)) {
1772 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1773 }
1774 }
1775 }
1777 public:
1778 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1780 ~G1ParScanThreadState() {
1781 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1782 }
1784 RefToScanQueue* refs() { return _refs; }
1785 ageTable* age_table() { return &_age_table; }
1787 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1788 return _alloc_buffers[purpose];
1789 }
1791 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1792 size_t undo_waste() const { return _undo_waste; }
1794 #ifdef ASSERT
1795 bool verify_ref(narrowOop* ref) const;
1796 bool verify_ref(oop* ref) const;
1797 bool verify_task(StarTask ref) const;
1798 #endif // ASSERT
1800 template <class T> void push_on_queue(T* ref) {
1801 assert(verify_ref(ref), "sanity");
1802 refs()->push(ref);
1803 }
1805 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1806 if (G1DeferredRSUpdate) {
1807 deferred_rs_update(from, p, tid);
1808 } else {
1809 immediate_rs_update(from, p, tid);
1810 }
1811 }
1813 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1815 HeapWord* obj = NULL;
1816 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1817 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1818 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1819 assert(gclab_word_size == alloc_buf->word_sz(),
1820 "dynamic resizing is not supported");
1821 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1822 alloc_buf->retire(false, false);
1824 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1825 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1826 // Otherwise.
1827 alloc_buf->set_buf(buf);
1829 obj = alloc_buf->allocate(word_sz);
1830 assert(obj != NULL, "buffer was definitely big enough...");
1831 } else {
1832 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1833 }
1834 return obj;
1835 }
1837 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1838 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1839 if (obj != NULL) return obj;
1840 return allocate_slow(purpose, word_sz);
1841 }
1843 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1844 if (alloc_buffer(purpose)->contains(obj)) {
1845 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1846 "should contain whole object");
1847 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1848 } else {
1849 CollectedHeap::fill_with_object(obj, word_sz);
1850 add_to_undo_waste(word_sz);
1851 }
1852 }
1854 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1855 _evac_failure_cl = evac_failure_cl;
1856 }
1857 OopsInHeapRegionClosure* evac_failure_closure() {
1858 return _evac_failure_cl;
1859 }
1861 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1862 _evac_cl = evac_cl;
1863 }
1865 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1866 _partial_scan_cl = partial_scan_cl;
1867 }
1869 int* hash_seed() { return &_hash_seed; }
1870 uint queue_num() { return _queue_num; }
1872 size_t term_attempts() const { return _term_attempts; }
1873 void note_term_attempt() { _term_attempts++; }
1875 void start_strong_roots() {
1876 _start_strong_roots = os::elapsedTime();
1877 }
1878 void end_strong_roots() {
1879 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1880 }
1881 double strong_roots_time() const { return _strong_roots_time; }
1883 void start_term_time() {
1884 note_term_attempt();
1885 _start_term = os::elapsedTime();
1886 }
1887 void end_term_time() {
1888 _term_time += (os::elapsedTime() - _start_term);
1889 }
1890 double term_time() const { return _term_time; }
1892 double elapsed_time() const {
1893 return os::elapsedTime() - _start;
1894 }
1896 static void
1897 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1898 void
1899 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1901 size_t* surviving_young_words() {
1902 // We add on to hide entry 0 which accumulates surviving words for
1903 // age -1 regions (i.e. non-young ones)
1904 return _surviving_young_words;
1905 }
1907 void retire_alloc_buffers() {
1908 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1909 size_t waste = _alloc_buffers[ap]->words_remaining();
1910 add_to_alloc_buffer_waste(waste);
1911 _alloc_buffers[ap]->retire(true, false);
1912 }
1913 }
1915 template <class T> void deal_with_reference(T* ref_to_scan) {
1916 if (has_partial_array_mask(ref_to_scan)) {
1917 _partial_scan_cl->do_oop_nv(ref_to_scan);
1918 } else {
1919 // Note: we can use "raw" versions of "region_containing" because
1920 // "obj_to_scan" is definitely in the heap, and is not in a
1921 // humongous region.
1922 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1923 _evac_cl->set_region(r);
1924 _evac_cl->do_oop_nv(ref_to_scan);
1925 }
1926 }
1928 void deal_with_reference(StarTask ref) {
1929 assert(verify_task(ref), "sanity");
1930 if (ref.is_narrow()) {
1931 deal_with_reference((narrowOop*)ref);
1932 } else {
1933 deal_with_reference((oop*)ref);
1934 }
1935 }
1937 public:
1938 void trim_queue();
1939 };
1941 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP