Mon, 06 Aug 2012 12:20:14 -0700
6818524: G1: use ergonomic resizing of PLABs
Summary: Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.
Reviewed-by: johnc, ysr
Contributed-by: Brandon Mitchell <brandon@twitter.com>
1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
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/shared/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 // PLAB sizing policy for survivors.
282 PLABStats _survivor_plab_stats;
284 // Alloc region used to satisfy allocation requests by the GC for
285 // old objects.
286 OldGCAllocRegion _old_gc_alloc_region;
288 // PLAB sizing policy for tenured objects.
289 PLABStats _old_plab_stats;
291 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
292 PLABStats* stats = NULL;
294 switch (purpose) {
295 case GCAllocForSurvived:
296 stats = &_survivor_plab_stats;
297 break;
298 case GCAllocForTenured:
299 stats = &_old_plab_stats;
300 break;
301 default:
302 assert(false, "unrecognized GCAllocPurpose");
303 }
305 return stats;
306 }
308 // The last old region we allocated to during the last GC.
309 // Typically, it is not full so we should re-use it during the next GC.
310 HeapRegion* _retained_old_gc_alloc_region;
312 // It specifies whether we should attempt to expand the heap after a
313 // region allocation failure. If heap expansion fails we set this to
314 // false so that we don't re-attempt the heap expansion (it's likely
315 // that subsequent expansion attempts will also fail if one fails).
316 // Currently, it is only consulted during GC and it's reset at the
317 // start of each GC.
318 bool _expand_heap_after_alloc_failure;
320 // It resets the mutator alloc region before new allocations can take place.
321 void init_mutator_alloc_region();
323 // It releases the mutator alloc region.
324 void release_mutator_alloc_region();
326 // It initializes the GC alloc regions at the start of a GC.
327 void init_gc_alloc_regions();
329 // It releases the GC alloc regions at the end of a GC.
330 void release_gc_alloc_regions();
332 // It does any cleanup that needs to be done on the GC alloc regions
333 // before a Full GC.
334 void abandon_gc_alloc_regions();
336 // Helper for monitoring and management support.
337 G1MonitoringSupport* _g1mm;
339 // Determines PLAB size for a particular allocation purpose.
340 size_t desired_plab_sz(GCAllocPurpose purpose);
342 // Outside of GC pauses, the number of bytes used in all regions other
343 // than the current allocation region.
344 size_t _summary_bytes_used;
346 // This is used for a quick test on whether a reference points into
347 // the collection set or not. Basically, we have an array, with one
348 // byte per region, and that byte denotes whether the corresponding
349 // region is in the collection set or not. The entry corresponding
350 // the bottom of the heap, i.e., region 0, is pointed to by
351 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
352 // biased so that it actually points to address 0 of the address
353 // space, to make the test as fast as possible (we can simply shift
354 // the address to address into it, instead of having to subtract the
355 // bottom of the heap from the address before shifting it; basically
356 // it works in the same way the card table works).
357 bool* _in_cset_fast_test;
359 // The allocated array used for the fast test on whether a reference
360 // points into the collection set or not. This field is also used to
361 // free the array.
362 bool* _in_cset_fast_test_base;
364 // The length of the _in_cset_fast_test_base array.
365 uint _in_cset_fast_test_length;
367 volatile unsigned _gc_time_stamp;
369 size_t* _surviving_young_words;
371 G1HRPrinter _hr_printer;
373 void setup_surviving_young_words();
374 void update_surviving_young_words(size_t* surv_young_words);
375 void cleanup_surviving_young_words();
377 // It decides whether an explicit GC should start a concurrent cycle
378 // instead of doing a STW GC. Currently, a concurrent cycle is
379 // explicitly started if:
380 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
381 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
382 // (c) cause == _g1_humongous_allocation
383 bool should_do_concurrent_full_gc(GCCause::Cause cause);
385 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
386 // concurrent cycles) we have started.
387 volatile unsigned int _old_marking_cycles_started;
389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
390 // concurrent cycles) we have completed.
391 volatile unsigned int _old_marking_cycles_completed;
393 // This is a non-product method that is helpful for testing. It is
394 // called at the end of a GC and artificially expands the heap by
395 // allocating a number of dead regions. This way we can induce very
396 // frequent marking cycles and stress the cleanup / concurrent
397 // cleanup code more (as all the regions that will be allocated by
398 // this method will be found dead by the marking cycle).
399 void allocate_dummy_regions() PRODUCT_RETURN;
401 // Clear RSets after a compaction. It also resets the GC time stamps.
402 void clear_rsets_post_compaction();
404 // If the HR printer is active, dump the state of the regions in the
405 // heap after a compaction.
406 void print_hrs_post_compaction();
408 // These are macros so that, if the assert fires, we get the correct
409 // line number, file, etc.
411 #define heap_locking_asserts_err_msg(_extra_message_) \
412 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
413 (_extra_message_), \
414 BOOL_TO_STR(Heap_lock->owned_by_self()), \
415 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
416 BOOL_TO_STR(Thread::current()->is_VM_thread()))
418 #define assert_heap_locked() \
419 do { \
420 assert(Heap_lock->owned_by_self(), \
421 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
422 } while (0)
424 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
425 do { \
426 assert(Heap_lock->owned_by_self() || \
427 (SafepointSynchronize::is_at_safepoint() && \
428 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
429 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
430 "should be at a safepoint")); \
431 } while (0)
433 #define assert_heap_locked_and_not_at_safepoint() \
434 do { \
435 assert(Heap_lock->owned_by_self() && \
436 !SafepointSynchronize::is_at_safepoint(), \
437 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
438 "should not be at a safepoint")); \
439 } while (0)
441 #define assert_heap_not_locked() \
442 do { \
443 assert(!Heap_lock->owned_by_self(), \
444 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
445 } while (0)
447 #define assert_heap_not_locked_and_not_at_safepoint() \
448 do { \
449 assert(!Heap_lock->owned_by_self() && \
450 !SafepointSynchronize::is_at_safepoint(), \
451 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
452 "should not be at a safepoint")); \
453 } while (0)
455 #define assert_at_safepoint(_should_be_vm_thread_) \
456 do { \
457 assert(SafepointSynchronize::is_at_safepoint() && \
458 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
459 heap_locking_asserts_err_msg("should be at a safepoint")); \
460 } while (0)
462 #define assert_not_at_safepoint() \
463 do { \
464 assert(!SafepointSynchronize::is_at_safepoint(), \
465 heap_locking_asserts_err_msg("should not be at a safepoint")); \
466 } while (0)
468 protected:
470 // The young region list.
471 YoungList* _young_list;
473 // The current policy object for the collector.
474 G1CollectorPolicy* _g1_policy;
476 // This is the second level of trying to allocate a new region. If
477 // new_region() didn't find a region on the free_list, this call will
478 // check whether there's anything available on the
479 // secondary_free_list and/or wait for more regions to appear on
480 // that list, if _free_regions_coming is set.
481 HeapRegion* new_region_try_secondary_free_list();
483 // Try to allocate a single non-humongous HeapRegion sufficient for
484 // an allocation of the given word_size. If do_expand is true,
485 // attempt to expand the heap if necessary to satisfy the allocation
486 // request.
487 HeapRegion* new_region(size_t word_size, bool do_expand);
489 // Attempt to satisfy a humongous allocation request of the given
490 // size by finding a contiguous set of free regions of num_regions
491 // length and remove them from the master free list. Return the
492 // index of the first region or G1_NULL_HRS_INDEX if the search
493 // was unsuccessful.
494 uint humongous_obj_allocate_find_first(uint num_regions,
495 size_t word_size);
497 // Initialize a contiguous set of free regions of length num_regions
498 // and starting at index first so that they appear as a single
499 // humongous region.
500 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
501 uint num_regions,
502 size_t word_size);
504 // Attempt to allocate a humongous object of the given size. Return
505 // NULL if unsuccessful.
506 HeapWord* humongous_obj_allocate(size_t word_size);
508 // The following two methods, allocate_new_tlab() and
509 // mem_allocate(), are the two main entry points from the runtime
510 // into the G1's allocation routines. They have the following
511 // assumptions:
512 //
513 // * They should both be called outside safepoints.
514 //
515 // * They should both be called without holding the Heap_lock.
516 //
517 // * All allocation requests for new TLABs should go to
518 // allocate_new_tlab().
519 //
520 // * All non-TLAB allocation requests should go to mem_allocate().
521 //
522 // * If either call cannot satisfy the allocation request using the
523 // current allocating region, they will try to get a new one. If
524 // this fails, they will attempt to do an evacuation pause and
525 // retry the allocation.
526 //
527 // * If all allocation attempts fail, even after trying to schedule
528 // an evacuation pause, allocate_new_tlab() will return NULL,
529 // whereas mem_allocate() will attempt a heap expansion and/or
530 // schedule a Full GC.
531 //
532 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
533 // should never be called with word_size being humongous. All
534 // humongous allocation requests should go to mem_allocate() which
535 // will satisfy them with a special path.
537 virtual HeapWord* allocate_new_tlab(size_t word_size);
539 virtual HeapWord* mem_allocate(size_t word_size,
540 bool* gc_overhead_limit_was_exceeded);
542 // The following three methods take a gc_count_before_ret
543 // parameter which is used to return the GC count if the method
544 // returns NULL. Given that we are required to read the GC count
545 // while holding the Heap_lock, and these paths will take the
546 // Heap_lock at some point, it's easier to get them to read the GC
547 // count while holding the Heap_lock before they return NULL instead
548 // of the caller (namely: mem_allocate()) having to also take the
549 // Heap_lock just to read the GC count.
551 // First-level mutator allocation attempt: try to allocate out of
552 // the mutator alloc region without taking the Heap_lock. This
553 // should only be used for non-humongous allocations.
554 inline HeapWord* attempt_allocation(size_t word_size,
555 unsigned int* gc_count_before_ret);
557 // Second-level mutator allocation attempt: take the Heap_lock and
558 // retry the allocation attempt, potentially scheduling a GC
559 // pause. This should only be used for non-humongous allocations.
560 HeapWord* attempt_allocation_slow(size_t word_size,
561 unsigned int* gc_count_before_ret);
563 // Takes the Heap_lock and attempts a humongous allocation. It can
564 // potentially schedule a GC pause.
565 HeapWord* attempt_allocation_humongous(size_t word_size,
566 unsigned int* gc_count_before_ret);
568 // Allocation attempt that should be called during safepoints (e.g.,
569 // at the end of a successful GC). expect_null_mutator_alloc_region
570 // specifies whether the mutator alloc region is expected to be NULL
571 // or not.
572 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
573 bool expect_null_mutator_alloc_region);
575 // It dirties the cards that cover the block so that so that the post
576 // write barrier never queues anything when updating objects on this
577 // block. It is assumed (and in fact we assert) that the block
578 // belongs to a young region.
579 inline void dirty_young_block(HeapWord* start, size_t word_size);
581 // Allocate blocks during garbage collection. Will ensure an
582 // allocation region, either by picking one or expanding the
583 // heap, and then allocate a block of the given size. The block
584 // may not be a humongous - it must fit into a single heap region.
585 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
587 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
588 HeapRegion* alloc_region,
589 bool par,
590 size_t word_size);
592 // Ensure that no further allocations can happen in "r", bearing in mind
593 // that parallel threads might be attempting allocations.
594 void par_allocate_remaining_space(HeapRegion* r);
596 // Allocation attempt during GC for a survivor object / PLAB.
597 inline HeapWord* survivor_attempt_allocation(size_t word_size);
599 // Allocation attempt during GC for an old object / PLAB.
600 inline HeapWord* old_attempt_allocation(size_t word_size);
602 // These methods are the "callbacks" from the G1AllocRegion class.
604 // For mutator alloc regions.
605 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
606 void retire_mutator_alloc_region(HeapRegion* alloc_region,
607 size_t allocated_bytes);
609 // For GC alloc regions.
610 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
611 GCAllocPurpose ap);
612 void retire_gc_alloc_region(HeapRegion* alloc_region,
613 size_t allocated_bytes, GCAllocPurpose ap);
615 // - if explicit_gc is true, the GC is for a System.gc() or a heap
616 // inspection request and should collect the entire heap
617 // - if clear_all_soft_refs is true, all soft references should be
618 // cleared during the GC
619 // - if explicit_gc is false, word_size describes the allocation that
620 // the GC should attempt (at least) to satisfy
621 // - it returns false if it is unable to do the collection due to the
622 // GC locker being active, true otherwise
623 bool do_collection(bool explicit_gc,
624 bool clear_all_soft_refs,
625 size_t word_size);
627 // Callback from VM_G1CollectFull operation.
628 // Perform a full collection.
629 void do_full_collection(bool clear_all_soft_refs);
631 // Resize the heap if necessary after a full collection. If this is
632 // after a collect-for allocation, "word_size" is the allocation size,
633 // and will be considered part of the used portion of the heap.
634 void resize_if_necessary_after_full_collection(size_t word_size);
636 // Callback from VM_G1CollectForAllocation operation.
637 // This function does everything necessary/possible to satisfy a
638 // failed allocation request (including collection, expansion, etc.)
639 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
641 // Attempting to expand the heap sufficiently
642 // to support an allocation of the given "word_size". If
643 // successful, perform the allocation and return the address of the
644 // allocated block, or else "NULL".
645 HeapWord* expand_and_allocate(size_t word_size);
647 // Process any reference objects discovered during
648 // an incremental evacuation pause.
649 void process_discovered_references();
651 // Enqueue any remaining discovered references
652 // after processing.
653 void enqueue_discovered_references();
655 public:
657 G1MonitoringSupport* g1mm() {
658 assert(_g1mm != NULL, "should have been initialized");
659 return _g1mm;
660 }
662 // Expand the garbage-first heap by at least the given size (in bytes!).
663 // Returns true if the heap was expanded by the requested amount;
664 // false otherwise.
665 // (Rounds up to a HeapRegion boundary.)
666 bool expand(size_t expand_bytes);
668 // Do anything common to GC's.
669 virtual void gc_prologue(bool full);
670 virtual void gc_epilogue(bool full);
672 // We register a region with the fast "in collection set" test. We
673 // simply set to true the array slot corresponding to this region.
674 void register_region_with_in_cset_fast_test(HeapRegion* r) {
675 assert(_in_cset_fast_test_base != NULL, "sanity");
676 assert(r->in_collection_set(), "invariant");
677 uint index = r->hrs_index();
678 assert(index < _in_cset_fast_test_length, "invariant");
679 assert(!_in_cset_fast_test_base[index], "invariant");
680 _in_cset_fast_test_base[index] = true;
681 }
683 // This is a fast test on whether a reference points into the
684 // collection set or not. It does not assume that the reference
685 // points into the heap; if it doesn't, it will return false.
686 bool in_cset_fast_test(oop obj) {
687 assert(_in_cset_fast_test != NULL, "sanity");
688 if (_g1_committed.contains((HeapWord*) obj)) {
689 // no need to subtract the bottom of the heap from obj,
690 // _in_cset_fast_test is biased
691 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
692 bool ret = _in_cset_fast_test[index];
693 // let's make sure the result is consistent with what the slower
694 // test returns
695 assert( ret || !obj_in_cs(obj), "sanity");
696 assert(!ret || obj_in_cs(obj), "sanity");
697 return ret;
698 } else {
699 return false;
700 }
701 }
703 void clear_cset_fast_test() {
704 assert(_in_cset_fast_test_base != NULL, "sanity");
705 memset(_in_cset_fast_test_base, false,
706 (size_t) _in_cset_fast_test_length * sizeof(bool));
707 }
709 // This is called at the start of either a concurrent cycle or a Full
710 // GC to update the number of old marking cycles started.
711 void increment_old_marking_cycles_started();
713 // This is called at the end of either a concurrent cycle or a Full
714 // GC to update the number of old marking cycles completed. Those two
715 // can happen in a nested fashion, i.e., we start a concurrent
716 // cycle, a Full GC happens half-way through it which ends first,
717 // and then the cycle notices that a Full GC happened and ends
718 // too. The concurrent parameter is a boolean to help us do a bit
719 // tighter consistency checking in the method. If concurrent is
720 // false, the caller is the inner caller in the nesting (i.e., the
721 // Full GC). If concurrent is true, the caller is the outer caller
722 // in this nesting (i.e., the concurrent cycle). Further nesting is
723 // not currently supported. The end of this call also notifies
724 // the FullGCCount_lock in case a Java thread is waiting for a full
725 // GC to happen (e.g., it called System.gc() with
726 // +ExplicitGCInvokesConcurrent).
727 void increment_old_marking_cycles_completed(bool concurrent);
729 unsigned int old_marking_cycles_completed() {
730 return _old_marking_cycles_completed;
731 }
733 G1HRPrinter* hr_printer() { return &_hr_printer; }
735 protected:
737 // Shrink the garbage-first heap by at most the given size (in bytes!).
738 // (Rounds down to a HeapRegion boundary.)
739 virtual void shrink(size_t expand_bytes);
740 void shrink_helper(size_t expand_bytes);
742 #if TASKQUEUE_STATS
743 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
744 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
745 void reset_taskqueue_stats();
746 #endif // TASKQUEUE_STATS
748 // Schedule the VM operation that will do an evacuation pause to
749 // satisfy an allocation request of word_size. *succeeded will
750 // return whether the VM operation was successful (it did do an
751 // evacuation pause) or not (another thread beat us to it or the GC
752 // locker was active). Given that we should not be holding the
753 // Heap_lock when we enter this method, we will pass the
754 // gc_count_before (i.e., total_collections()) as a parameter since
755 // it has to be read while holding the Heap_lock. Currently, both
756 // methods that call do_collection_pause() release the Heap_lock
757 // before the call, so it's easy to read gc_count_before just before.
758 HeapWord* do_collection_pause(size_t word_size,
759 unsigned int gc_count_before,
760 bool* succeeded);
762 // The guts of the incremental collection pause, executed by the vm
763 // thread. It returns false if it is unable to do the collection due
764 // to the GC locker being active, true otherwise
765 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
767 // Actually do the work of evacuating the collection set.
768 void evacuate_collection_set();
770 // The g1 remembered set of the heap.
771 G1RemSet* _g1_rem_set;
772 // And it's mod ref barrier set, used to track updates for the above.
773 ModRefBarrierSet* _mr_bs;
775 // A set of cards that cover the objects for which the Rsets should be updated
776 // concurrently after the collection.
777 DirtyCardQueueSet _dirty_card_queue_set;
779 // The Heap Region Rem Set Iterator.
780 HeapRegionRemSetIterator** _rem_set_iterator;
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);
798 // Abandon the current collection set without recording policy
799 // statistics or updating free lists.
800 void abandon_collection_set(HeapRegion* cs_head);
802 // Applies "scan_non_heap_roots" to roots outside the heap,
803 // "scan_rs" to roots inside the heap (having done "set_region" to
804 // indicate the region in which the root resides), and does "scan_perm"
805 // (setting the generation to the perm generation.) If "scan_rs" is
806 // NULL, then this step is skipped. The "worker_i"
807 // param is for use with parallel roots processing, and should be
808 // the "i" of the calling parallel worker thread's work(i) function.
809 // In the sequential case this param will be ignored.
810 void g1_process_strong_roots(bool collecting_perm_gen,
811 ScanningOption so,
812 OopClosure* scan_non_heap_roots,
813 OopsInHeapRegionClosure* scan_rs,
814 OopsInGenClosure* scan_perm,
815 int worker_i);
817 // Apply "blk" to all the weak roots of the system. These include
818 // JNI weak roots, the code cache, system dictionary, symbol table,
819 // string table, and referents of reachable weak refs.
820 void g1_process_weak_roots(OopClosure* root_closure,
821 OopClosure* non_root_closure);
823 // Frees a non-humongous region by initializing its contents and
824 // adding it to the free list that's passed as a parameter (this is
825 // usually a local list which will be appended to the master free
826 // list later). The used bytes of freed regions are accumulated in
827 // pre_used. If par is true, the region's RSet will not be freed
828 // up. The assumption is that this will be done later.
829 void free_region(HeapRegion* hr,
830 size_t* pre_used,
831 FreeRegionList* free_list,
832 bool par);
834 // Frees a humongous region by collapsing it into individual regions
835 // and calling free_region() for each of them. The freed regions
836 // will be added to the free list that's passed as a parameter (this
837 // is usually a local list which will be appended to the master free
838 // list later). The used bytes of freed regions are accumulated in
839 // pre_used. If par is true, the region's RSet will not be freed
840 // up. The assumption is that this will be done later.
841 void free_humongous_region(HeapRegion* hr,
842 size_t* pre_used,
843 FreeRegionList* free_list,
844 HumongousRegionSet* humongous_proxy_set,
845 bool par);
847 // Notifies all the necessary spaces that the committed space has
848 // been updated (either expanded or shrunk). It should be called
849 // after _g1_storage is updated.
850 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
852 // The concurrent marker (and the thread it runs in.)
853 ConcurrentMark* _cm;
854 ConcurrentMarkThread* _cmThread;
855 bool _mark_in_progress;
857 // The concurrent refiner.
858 ConcurrentG1Refine* _cg1r;
860 // The parallel task queues
861 RefToScanQueueSet *_task_queues;
863 // True iff a evacuation has failed in the current collection.
864 bool _evacuation_failed;
866 // Set the attribute indicating whether evacuation has failed in the
867 // current collection.
868 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
870 // Failed evacuations cause some logical from-space objects to have
871 // forwarding pointers to themselves. Reset them.
872 void remove_self_forwarding_pointers();
874 // When one is non-null, so is the other. Together, they each pair is
875 // an object with a preserved mark, and its mark value.
876 GrowableArray<oop>* _objs_with_preserved_marks;
877 GrowableArray<markOop>* _preserved_marks_of_objs;
879 // Preserve the mark of "obj", if necessary, in preparation for its mark
880 // word being overwritten with a self-forwarding-pointer.
881 void preserve_mark_if_necessary(oop obj, markOop m);
883 // The stack of evac-failure objects left to be scanned.
884 GrowableArray<oop>* _evac_failure_scan_stack;
885 // The closure to apply to evac-failure objects.
887 OopsInHeapRegionClosure* _evac_failure_closure;
888 // Set the field above.
889 void
890 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
891 _evac_failure_closure = evac_failure_closure;
892 }
894 // Push "obj" on the scan stack.
895 void push_on_evac_failure_scan_stack(oop obj);
896 // Process scan stack entries until the stack is empty.
897 void drain_evac_failure_scan_stack();
898 // True iff an invocation of "drain_scan_stack" is in progress; to
899 // prevent unnecessary recursion.
900 bool _drain_in_progress;
902 // Do any necessary initialization for evacuation-failure handling.
903 // "cl" is the closure that will be used to process evac-failure
904 // objects.
905 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
906 // Do any necessary cleanup for evacuation-failure handling data
907 // structures.
908 void finalize_for_evac_failure();
910 // An attempt to evacuate "obj" has failed; take necessary steps.
911 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
912 void handle_evacuation_failure_common(oop obj, markOop m);
914 // ("Weak") Reference processing support.
915 //
916 // G1 has 2 instances of the referece processor class. One
917 // (_ref_processor_cm) handles reference object discovery
918 // and subsequent processing during concurrent marking cycles.
919 //
920 // The other (_ref_processor_stw) handles reference object
921 // discovery and processing during full GCs and incremental
922 // evacuation pauses.
923 //
924 // During an incremental pause, reference discovery will be
925 // temporarily disabled for _ref_processor_cm and will be
926 // enabled for _ref_processor_stw. At the end of the evacuation
927 // pause references discovered by _ref_processor_stw will be
928 // processed and discovery will be disabled. The previous
929 // setting for reference object discovery for _ref_processor_cm
930 // will be re-instated.
931 //
932 // At the start of marking:
933 // * Discovery by the CM ref processor is verified to be inactive
934 // and it's discovered lists are empty.
935 // * Discovery by the CM ref processor is then enabled.
936 //
937 // At the end of marking:
938 // * Any references on the CM ref processor's discovered
939 // lists are processed (possibly MT).
940 //
941 // At the start of full GC we:
942 // * Disable discovery by the CM ref processor and
943 // empty CM ref processor's discovered lists
944 // (without processing any entries).
945 // * Verify that the STW ref processor is inactive and it's
946 // discovered lists are empty.
947 // * Temporarily set STW ref processor discovery as single threaded.
948 // * Temporarily clear the STW ref processor's _is_alive_non_header
949 // field.
950 // * Finally enable discovery by the STW ref processor.
951 //
952 // The STW ref processor is used to record any discovered
953 // references during the full GC.
954 //
955 // At the end of a full GC we:
956 // * Enqueue any reference objects discovered by the STW ref processor
957 // that have non-live referents. This has the side-effect of
958 // making the STW ref processor inactive by disabling discovery.
959 // * Verify that the CM ref processor is still inactive
960 // and no references have been placed on it's discovered
961 // lists (also checked as a precondition during initial marking).
963 // The (stw) reference processor...
964 ReferenceProcessor* _ref_processor_stw;
966 // During reference object discovery, the _is_alive_non_header
967 // closure (if non-null) is applied to the referent object to
968 // determine whether the referent is live. If so then the
969 // reference object does not need to be 'discovered' and can
970 // be treated as a regular oop. This has the benefit of reducing
971 // the number of 'discovered' reference objects that need to
972 // be processed.
973 //
974 // Instance of the is_alive closure for embedding into the
975 // STW reference processor as the _is_alive_non_header field.
976 // Supplying a value for the _is_alive_non_header field is
977 // optional but doing so prevents unnecessary additions to
978 // the discovered lists during reference discovery.
979 G1STWIsAliveClosure _is_alive_closure_stw;
981 // The (concurrent marking) reference processor...
982 ReferenceProcessor* _ref_processor_cm;
984 // Instance of the concurrent mark is_alive closure for embedding
985 // into the Concurrent Marking reference processor as the
986 // _is_alive_non_header field. Supplying a value for the
987 // _is_alive_non_header field is optional but doing so prevents
988 // unnecessary additions to the discovered lists during reference
989 // discovery.
990 G1CMIsAliveClosure _is_alive_closure_cm;
992 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
993 HeapRegion** _worker_cset_start_region;
995 // Time stamp to validate the regions recorded in the cache
996 // used by G1CollectedHeap::start_cset_region_for_worker().
997 // The heap region entry for a given worker is valid iff
998 // the associated time stamp value matches the current value
999 // of G1CollectedHeap::_gc_time_stamp.
1000 unsigned int* _worker_cset_start_region_time_stamp;
1002 enum G1H_process_strong_roots_tasks {
1003 G1H_PS_filter_satb_buffers,
1004 G1H_PS_refProcessor_oops_do,
1005 // Leave this one last.
1006 G1H_PS_NumElements
1007 };
1009 SubTasksDone* _process_strong_tasks;
1011 volatile bool _free_regions_coming;
1013 public:
1015 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1017 void set_refine_cte_cl_concurrency(bool concurrent);
1019 RefToScanQueue *task_queue(int i) const;
1021 // A set of cards where updates happened during the GC
1022 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1024 // A DirtyCardQueueSet that is used to hold cards that contain
1025 // references into the current collection set. This is used to
1026 // update the remembered sets of the regions in the collection
1027 // set in the event of an evacuation failure.
1028 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1029 { return _into_cset_dirty_card_queue_set; }
1031 // Create a G1CollectedHeap with the specified policy.
1032 // Must call the initialize method afterwards.
1033 // May not return if something goes wrong.
1034 G1CollectedHeap(G1CollectorPolicy* policy);
1036 // Initialize the G1CollectedHeap to have the initial and
1037 // maximum sizes, permanent generation, and remembered and barrier sets
1038 // specified by the policy object.
1039 jint initialize();
1041 // Initialize weak reference processing.
1042 virtual void ref_processing_init();
1044 void set_par_threads(uint t) {
1045 SharedHeap::set_par_threads(t);
1046 // Done in SharedHeap but oddly there are
1047 // two _process_strong_tasks's in a G1CollectedHeap
1048 // so do it here too.
1049 _process_strong_tasks->set_n_threads(t);
1050 }
1052 // Set _n_par_threads according to a policy TBD.
1053 void set_par_threads();
1055 void set_n_termination(int t) {
1056 _process_strong_tasks->set_n_threads(t);
1057 }
1059 virtual CollectedHeap::Name kind() const {
1060 return CollectedHeap::G1CollectedHeap;
1061 }
1063 // The current policy object for the collector.
1064 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1066 // Adaptive size policy. No such thing for g1.
1067 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1069 // The rem set and barrier set.
1070 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1071 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1073 // The rem set iterator.
1074 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1075 return _rem_set_iterator[i];
1076 }
1078 HeapRegionRemSetIterator* rem_set_iterator() {
1079 return _rem_set_iterator[0];
1080 }
1082 unsigned get_gc_time_stamp() {
1083 return _gc_time_stamp;
1084 }
1086 void reset_gc_time_stamp() {
1087 _gc_time_stamp = 0;
1088 OrderAccess::fence();
1089 // Clear the cached CSet starting regions and time stamps.
1090 // Their validity is dependent on the GC timestamp.
1091 clear_cset_start_regions();
1092 }
1094 void check_gc_time_stamps() PRODUCT_RETURN;
1096 void increment_gc_time_stamp() {
1097 ++_gc_time_stamp;
1098 OrderAccess::fence();
1099 }
1101 // Reset the given region's GC timestamp. If it's starts humongous,
1102 // also reset the GC timestamp of its corresponding
1103 // continues humongous regions too.
1104 void reset_gc_time_stamps(HeapRegion* hr);
1106 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1107 DirtyCardQueue* into_cset_dcq,
1108 bool concurrent, int worker_i);
1110 // The shared block offset table array.
1111 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1113 // Reference Processing accessors
1115 // The STW reference processor....
1116 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1118 // The Concurent Marking reference processor...
1119 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1121 virtual size_t capacity() const;
1122 virtual size_t used() const;
1123 // This should be called when we're not holding the heap lock. The
1124 // result might be a bit inaccurate.
1125 size_t used_unlocked() const;
1126 size_t recalculate_used() const;
1128 // These virtual functions do the actual allocation.
1129 // Some heaps may offer a contiguous region for shared non-blocking
1130 // allocation, via inlined code (by exporting the address of the top and
1131 // end fields defining the extent of the contiguous allocation region.)
1132 // But G1CollectedHeap doesn't yet support this.
1134 // Return an estimate of the maximum allocation that could be performed
1135 // without triggering any collection or expansion activity. In a
1136 // generational collector, for example, this is probably the largest
1137 // allocation that could be supported (without expansion) in the youngest
1138 // generation. It is "unsafe" because no locks are taken; the result
1139 // should be treated as an approximation, not a guarantee, for use in
1140 // heuristic resizing decisions.
1141 virtual size_t unsafe_max_alloc();
1143 virtual bool is_maximal_no_gc() const {
1144 return _g1_storage.uncommitted_size() == 0;
1145 }
1147 // The total number of regions in the heap.
1148 uint n_regions() { return _hrs.length(); }
1150 // The max number of regions in the heap.
1151 uint max_regions() { return _hrs.max_length(); }
1153 // The number of regions that are completely free.
1154 uint free_regions() { return _free_list.length(); }
1156 // The number of regions that are not completely free.
1157 uint used_regions() { return n_regions() - free_regions(); }
1159 // The number of regions available for "regular" expansion.
1160 uint expansion_regions() { return _expansion_regions; }
1162 // Factory method for HeapRegion instances. It will return NULL if
1163 // the allocation fails.
1164 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1166 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1167 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1168 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1169 void verify_dirty_young_regions() PRODUCT_RETURN;
1171 // verify_region_sets() performs verification over the region
1172 // lists. It will be compiled in the product code to be used when
1173 // necessary (i.e., during heap verification).
1174 void verify_region_sets();
1176 // verify_region_sets_optional() is planted in the code for
1177 // list verification in non-product builds (and it can be enabled in
1178 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1179 #if HEAP_REGION_SET_FORCE_VERIFY
1180 void verify_region_sets_optional() {
1181 verify_region_sets();
1182 }
1183 #else // HEAP_REGION_SET_FORCE_VERIFY
1184 void verify_region_sets_optional() { }
1185 #endif // HEAP_REGION_SET_FORCE_VERIFY
1187 #ifdef ASSERT
1188 bool is_on_master_free_list(HeapRegion* hr) {
1189 return hr->containing_set() == &_free_list;
1190 }
1192 bool is_in_humongous_set(HeapRegion* hr) {
1193 return hr->containing_set() == &_humongous_set;
1194 }
1195 #endif // ASSERT
1197 // Wrapper for the region list operations that can be called from
1198 // methods outside this class.
1200 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1201 _secondary_free_list.add_as_tail(list);
1202 }
1204 void append_secondary_free_list() {
1205 _free_list.add_as_head(&_secondary_free_list);
1206 }
1208 void append_secondary_free_list_if_not_empty_with_lock() {
1209 // If the secondary free list looks empty there's no reason to
1210 // take the lock and then try to append it.
1211 if (!_secondary_free_list.is_empty()) {
1212 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1213 append_secondary_free_list();
1214 }
1215 }
1217 void old_set_remove(HeapRegion* hr) {
1218 _old_set.remove(hr);
1219 }
1221 size_t non_young_capacity_bytes() {
1222 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1223 }
1225 void set_free_regions_coming();
1226 void reset_free_regions_coming();
1227 bool free_regions_coming() { return _free_regions_coming; }
1228 void wait_while_free_regions_coming();
1230 // Determine whether the given region is one that we are using as an
1231 // old GC alloc region.
1232 bool is_old_gc_alloc_region(HeapRegion* hr) {
1233 return hr == _retained_old_gc_alloc_region;
1234 }
1236 // Perform a collection of the heap; intended for use in implementing
1237 // "System.gc". This probably implies as full a collection as the
1238 // "CollectedHeap" supports.
1239 virtual void collect(GCCause::Cause cause);
1241 // The same as above but assume that the caller holds the Heap_lock.
1242 void collect_locked(GCCause::Cause cause);
1244 // This interface assumes that it's being called by the
1245 // vm thread. It collects the heap assuming that the
1246 // heap lock is already held and that we are executing in
1247 // the context of the vm thread.
1248 virtual void collect_as_vm_thread(GCCause::Cause cause);
1250 // True iff a evacuation has failed in the most-recent collection.
1251 bool evacuation_failed() { return _evacuation_failed; }
1253 // It will free a region if it has allocated objects in it that are
1254 // all dead. It calls either free_region() or
1255 // free_humongous_region() depending on the type of the region that
1256 // is passed to it.
1257 void free_region_if_empty(HeapRegion* hr,
1258 size_t* pre_used,
1259 FreeRegionList* free_list,
1260 OldRegionSet* old_proxy_set,
1261 HumongousRegionSet* humongous_proxy_set,
1262 HRRSCleanupTask* hrrs_cleanup_task,
1263 bool par);
1265 // It appends the free list to the master free list and updates the
1266 // master humongous list according to the contents of the proxy
1267 // list. It also adjusts the total used bytes according to pre_used
1268 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1269 void update_sets_after_freeing_regions(size_t pre_used,
1270 FreeRegionList* free_list,
1271 OldRegionSet* old_proxy_set,
1272 HumongousRegionSet* humongous_proxy_set,
1273 bool par);
1275 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1276 virtual bool is_in(const void* p) const;
1278 // Return "TRUE" iff the given object address is within the collection
1279 // set.
1280 inline bool obj_in_cs(oop obj);
1282 // Return "TRUE" iff the given object address is in the reserved
1283 // region of g1 (excluding the permanent generation).
1284 bool is_in_g1_reserved(const void* p) const {
1285 return _g1_reserved.contains(p);
1286 }
1288 // Returns a MemRegion that corresponds to the space that has been
1289 // reserved for the heap
1290 MemRegion g1_reserved() {
1291 return _g1_reserved;
1292 }
1294 // Returns a MemRegion that corresponds to the space that has been
1295 // committed in the heap
1296 MemRegion g1_committed() {
1297 return _g1_committed;
1298 }
1300 virtual bool is_in_closed_subset(const void* p) const;
1302 // This resets the card table to all zeros. It is used after
1303 // a collection pause which used the card table to claim cards.
1304 void cleanUpCardTable();
1306 // Iteration functions.
1308 // Iterate over all the ref-containing fields of all objects, calling
1309 // "cl.do_oop" on each.
1310 virtual void oop_iterate(OopClosure* cl) {
1311 oop_iterate(cl, true);
1312 }
1313 void oop_iterate(OopClosure* cl, bool do_perm);
1315 // Same as above, restricted to a memory region.
1316 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1317 oop_iterate(mr, cl, true);
1318 }
1319 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1321 // Iterate over all objects, calling "cl.do_object" on each.
1322 virtual void object_iterate(ObjectClosure* cl) {
1323 object_iterate(cl, true);
1324 }
1325 virtual void safe_object_iterate(ObjectClosure* cl) {
1326 object_iterate(cl, true);
1327 }
1328 void object_iterate(ObjectClosure* cl, bool do_perm);
1330 // Iterate over all objects allocated since the last collection, calling
1331 // "cl.do_object" on each. The heap must have been initialized properly
1332 // to support this function, or else this call will fail.
1333 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1335 // Iterate over all spaces in use in the heap, in ascending address order.
1336 virtual void space_iterate(SpaceClosure* cl);
1338 // Iterate over heap regions, in address order, terminating the
1339 // iteration early if the "doHeapRegion" method returns "true".
1340 void heap_region_iterate(HeapRegionClosure* blk) const;
1342 // Return the region with the given index. It assumes the index is valid.
1343 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1345 // Divide the heap region sequence into "chunks" of some size (the number
1346 // of regions divided by the number of parallel threads times some
1347 // overpartition factor, currently 4). Assumes that this will be called
1348 // in parallel by ParallelGCThreads worker threads with discinct worker
1349 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1350 // calls will use the same "claim_value", and that that claim value is
1351 // different from the claim_value of any heap region before the start of
1352 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1353 // attempting to claim the first region in each chunk, and, if
1354 // successful, applying the closure to each region in the chunk (and
1355 // setting the claim value of the second and subsequent regions of the
1356 // chunk.) For now requires that "doHeapRegion" always returns "false",
1357 // i.e., that a closure never attempt to abort a traversal.
1358 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1359 uint worker,
1360 uint no_of_par_workers,
1361 jint claim_value);
1363 // It resets all the region claim values to the default.
1364 void reset_heap_region_claim_values();
1366 // Resets the claim values of regions in the current
1367 // collection set to the default.
1368 void reset_cset_heap_region_claim_values();
1370 #ifdef ASSERT
1371 bool check_heap_region_claim_values(jint claim_value);
1373 // Same as the routine above but only checks regions in the
1374 // current collection set.
1375 bool check_cset_heap_region_claim_values(jint claim_value);
1376 #endif // ASSERT
1378 // Clear the cached cset start regions and (more importantly)
1379 // the time stamps. Called when we reset the GC time stamp.
1380 void clear_cset_start_regions();
1382 // Given the id of a worker, obtain or calculate a suitable
1383 // starting region for iterating over the current collection set.
1384 HeapRegion* start_cset_region_for_worker(int worker_i);
1386 // This is a convenience method that is used by the
1387 // HeapRegionIterator classes to calculate the starting region for
1388 // each worker so that they do not all start from the same region.
1389 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1391 // Iterate over the regions (if any) in the current collection set.
1392 void collection_set_iterate(HeapRegionClosure* blk);
1394 // As above but starting from region r
1395 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1397 // Returns the first (lowest address) compactible space in the heap.
1398 virtual CompactibleSpace* first_compactible_space();
1400 // A CollectedHeap will contain some number of spaces. This finds the
1401 // space containing a given address, or else returns NULL.
1402 virtual Space* space_containing(const void* addr) const;
1404 // A G1CollectedHeap will contain some number of heap regions. This
1405 // finds the region containing a given address, or else returns NULL.
1406 template <class T>
1407 inline HeapRegion* heap_region_containing(const T addr) const;
1409 // Like the above, but requires "addr" to be in the heap (to avoid a
1410 // null-check), and unlike the above, may return an continuing humongous
1411 // region.
1412 template <class T>
1413 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1415 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1416 // each address in the (reserved) heap is a member of exactly
1417 // one block. The defining characteristic of a block is that it is
1418 // possible to find its size, and thus to progress forward to the next
1419 // block. (Blocks may be of different sizes.) Thus, blocks may
1420 // represent Java objects, or they might be free blocks in a
1421 // free-list-based heap (or subheap), as long as the two kinds are
1422 // distinguishable and the size of each is determinable.
1424 // Returns the address of the start of the "block" that contains the
1425 // address "addr". We say "blocks" instead of "object" since some heaps
1426 // may not pack objects densely; a chunk may either be an object or a
1427 // non-object.
1428 virtual HeapWord* block_start(const void* addr) const;
1430 // Requires "addr" to be the start of a chunk, and returns its size.
1431 // "addr + size" is required to be the start of a new chunk, or the end
1432 // of the active area of the heap.
1433 virtual size_t block_size(const HeapWord* addr) const;
1435 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1436 // the block is an object.
1437 virtual bool block_is_obj(const HeapWord* addr) const;
1439 // Does this heap support heap inspection? (+PrintClassHistogram)
1440 virtual bool supports_heap_inspection() const { return true; }
1442 // Section on thread-local allocation buffers (TLABs)
1443 // See CollectedHeap for semantics.
1445 virtual bool supports_tlab_allocation() const;
1446 virtual size_t tlab_capacity(Thread* thr) const;
1447 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1449 // Can a compiler initialize a new object without store barriers?
1450 // This permission only extends from the creation of a new object
1451 // via a TLAB up to the first subsequent safepoint. If such permission
1452 // is granted for this heap type, the compiler promises to call
1453 // defer_store_barrier() below on any slow path allocation of
1454 // a new object for which such initializing store barriers will
1455 // have been elided. G1, like CMS, allows this, but should be
1456 // ready to provide a compensating write barrier as necessary
1457 // if that storage came out of a non-young region. The efficiency
1458 // of this implementation depends crucially on being able to
1459 // answer very efficiently in constant time whether a piece of
1460 // storage in the heap comes from a young region or not.
1461 // See ReduceInitialCardMarks.
1462 virtual bool can_elide_tlab_store_barriers() const {
1463 return true;
1464 }
1466 virtual bool card_mark_must_follow_store() const {
1467 return true;
1468 }
1470 bool is_in_young(const oop obj) {
1471 HeapRegion* hr = heap_region_containing(obj);
1472 return hr != NULL && hr->is_young();
1473 }
1475 #ifdef ASSERT
1476 virtual bool is_in_partial_collection(const void* p);
1477 #endif
1479 virtual bool is_scavengable(const void* addr);
1481 // We don't need barriers for initializing stores to objects
1482 // in the young gen: for the SATB pre-barrier, there is no
1483 // pre-value that needs to be remembered; for the remembered-set
1484 // update logging post-barrier, we don't maintain remembered set
1485 // information for young gen objects.
1486 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1487 return is_in_young(new_obj);
1488 }
1490 // Can a compiler elide a store barrier when it writes
1491 // a permanent oop into the heap? Applies when the compiler
1492 // is storing x to the heap, where x->is_perm() is true.
1493 virtual bool can_elide_permanent_oop_store_barriers() const {
1494 // At least until perm gen collection is also G1-ified, at
1495 // which point this should return false.
1496 return true;
1497 }
1499 // Returns "true" iff the given word_size is "very large".
1500 static bool isHumongous(size_t word_size) {
1501 // Note this has to be strictly greater-than as the TLABs
1502 // are capped at the humongous thresold and we want to
1503 // ensure that we don't try to allocate a TLAB as
1504 // humongous and that we don't allocate a humongous
1505 // object in a TLAB.
1506 return word_size > _humongous_object_threshold_in_words;
1507 }
1509 // Update mod union table with the set of dirty cards.
1510 void updateModUnion();
1512 // Set the mod union bits corresponding to the given memRegion. Note
1513 // that this is always a safe operation, since it doesn't clear any
1514 // bits.
1515 void markModUnionRange(MemRegion mr);
1517 // Records the fact that a marking phase is no longer in progress.
1518 void set_marking_complete() {
1519 _mark_in_progress = false;
1520 }
1521 void set_marking_started() {
1522 _mark_in_progress = true;
1523 }
1524 bool mark_in_progress() {
1525 return _mark_in_progress;
1526 }
1528 // Print the maximum heap capacity.
1529 virtual size_t max_capacity() const;
1531 virtual jlong millis_since_last_gc();
1533 // Perform any cleanup actions necessary before allowing a verification.
1534 virtual void prepare_for_verify();
1536 // Perform verification.
1538 // vo == UsePrevMarking -> use "prev" marking information,
1539 // vo == UseNextMarking -> use "next" marking information
1540 // vo == UseMarkWord -> use the mark word in the object header
1541 //
1542 // NOTE: Only the "prev" marking information is guaranteed to be
1543 // consistent most of the time, so most calls to this should use
1544 // vo == UsePrevMarking.
1545 // Currently, there is only one case where this is called with
1546 // vo == UseNextMarking, which is to verify the "next" marking
1547 // information at the end of remark.
1548 // Currently there is only one place where this is called with
1549 // vo == UseMarkWord, which is to verify the marking during a
1550 // full GC.
1551 void verify(bool silent, VerifyOption vo);
1553 // Override; it uses the "prev" marking information
1554 virtual void verify(bool silent);
1555 virtual void print_on(outputStream* st) const;
1556 virtual void print_extended_on(outputStream* st) const;
1558 virtual void print_gc_threads_on(outputStream* st) const;
1559 virtual void gc_threads_do(ThreadClosure* tc) const;
1561 // Override
1562 void print_tracing_info() const;
1564 // The following two methods are helpful for debugging RSet issues.
1565 void print_cset_rsets() PRODUCT_RETURN;
1566 void print_all_rsets() PRODUCT_RETURN;
1568 // Convenience function to be used in situations where the heap type can be
1569 // asserted to be this type.
1570 static G1CollectedHeap* heap();
1572 void set_region_short_lived_locked(HeapRegion* hr);
1573 // add appropriate methods for any other surv rate groups
1575 YoungList* young_list() { return _young_list; }
1577 // debugging
1578 bool check_young_list_well_formed() {
1579 return _young_list->check_list_well_formed();
1580 }
1582 bool check_young_list_empty(bool check_heap,
1583 bool check_sample = true);
1585 // *** Stuff related to concurrent marking. It's not clear to me that so
1586 // many of these need to be public.
1588 // The functions below are helper functions that a subclass of
1589 // "CollectedHeap" can use in the implementation of its virtual
1590 // functions.
1591 // This performs a concurrent marking of the live objects in a
1592 // bitmap off to the side.
1593 void doConcurrentMark();
1595 bool isMarkedPrev(oop obj) const;
1596 bool isMarkedNext(oop obj) const;
1598 // Determine if an object is dead, given the object and also
1599 // the region to which the object belongs. An object is dead
1600 // iff a) it was not allocated since the last mark and b) it
1601 // is not marked.
1603 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1604 return
1605 !hr->obj_allocated_since_prev_marking(obj) &&
1606 !isMarkedPrev(obj);
1607 }
1609 // This function returns true when an object has been
1610 // around since the previous marking and hasn't yet
1611 // been marked during this marking.
1613 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1614 return
1615 !hr->obj_allocated_since_next_marking(obj) &&
1616 !isMarkedNext(obj);
1617 }
1619 // Determine if an object is dead, given only the object itself.
1620 // This will find the region to which the object belongs and
1621 // then call the region version of the same function.
1623 // Added if it is in permanent gen it isn't dead.
1624 // Added if it is NULL it isn't dead.
1626 bool is_obj_dead(const oop obj) const {
1627 const HeapRegion* hr = heap_region_containing(obj);
1628 if (hr == NULL) {
1629 if (Universe::heap()->is_in_permanent(obj))
1630 return false;
1631 else if (obj == NULL) return false;
1632 else return true;
1633 }
1634 else return is_obj_dead(obj, hr);
1635 }
1637 bool is_obj_ill(const oop obj) const {
1638 const HeapRegion* hr = heap_region_containing(obj);
1639 if (hr == NULL) {
1640 if (Universe::heap()->is_in_permanent(obj))
1641 return false;
1642 else if (obj == NULL) return false;
1643 else return true;
1644 }
1645 else return is_obj_ill(obj, hr);
1646 }
1648 // The methods below are here for convenience and dispatch the
1649 // appropriate method depending on value of the given VerifyOption
1650 // parameter. The options for that parameter are:
1651 //
1652 // vo == UsePrevMarking -> use "prev" marking information,
1653 // vo == UseNextMarking -> use "next" marking information,
1654 // vo == UseMarkWord -> use mark word from object header
1656 bool is_obj_dead_cond(const oop obj,
1657 const HeapRegion* hr,
1658 const VerifyOption vo) const {
1659 switch (vo) {
1660 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1661 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1662 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1663 default: ShouldNotReachHere();
1664 }
1665 return false; // keep some compilers happy
1666 }
1668 bool is_obj_dead_cond(const oop obj,
1669 const VerifyOption vo) const {
1670 switch (vo) {
1671 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1672 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1673 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1674 default: ShouldNotReachHere();
1675 }
1676 return false; // keep some compilers happy
1677 }
1679 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1680 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1681 bool is_marked(oop obj, VerifyOption vo);
1682 const char* top_at_mark_start_str(VerifyOption vo);
1684 // The following is just to alert the verification code
1685 // that a full collection has occurred and that the
1686 // remembered sets are no longer up to date.
1687 bool _full_collection;
1688 void set_full_collection() { _full_collection = true;}
1689 void clear_full_collection() {_full_collection = false;}
1690 bool full_collection() {return _full_collection;}
1692 ConcurrentMark* concurrent_mark() const { return _cm; }
1693 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1695 // The dirty cards region list is used to record a subset of regions
1696 // whose cards need clearing. The list if populated during the
1697 // remembered set scanning and drained during the card table
1698 // cleanup. Although the methods are reentrant, population/draining
1699 // phases must not overlap. For synchronization purposes the last
1700 // element on the list points to itself.
1701 HeapRegion* _dirty_cards_region_list;
1702 void push_dirty_cards_region(HeapRegion* hr);
1703 HeapRegion* pop_dirty_cards_region();
1705 public:
1706 void stop_conc_gc_threads();
1708 size_t pending_card_num();
1709 size_t max_pending_card_num();
1710 size_t cards_scanned();
1712 protected:
1713 size_t _max_heap_capacity;
1714 };
1716 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1717 private:
1718 bool _retired;
1720 public:
1721 G1ParGCAllocBuffer(size_t gclab_word_size);
1723 void set_buf(HeapWord* buf) {
1724 ParGCAllocBuffer::set_buf(buf);
1725 _retired = false;
1726 }
1728 void retire(bool end_of_gc, bool retain) {
1729 if (_retired)
1730 return;
1731 ParGCAllocBuffer::retire(end_of_gc, retain);
1732 _retired = true;
1733 }
1734 };
1736 class G1ParScanThreadState : public StackObj {
1737 protected:
1738 G1CollectedHeap* _g1h;
1739 RefToScanQueue* _refs;
1740 DirtyCardQueue _dcq;
1741 CardTableModRefBS* _ct_bs;
1742 G1RemSet* _g1_rem;
1744 G1ParGCAllocBuffer _surviving_alloc_buffer;
1745 G1ParGCAllocBuffer _tenured_alloc_buffer;
1746 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1747 ageTable _age_table;
1749 size_t _alloc_buffer_waste;
1750 size_t _undo_waste;
1752 OopsInHeapRegionClosure* _evac_failure_cl;
1753 G1ParScanHeapEvacClosure* _evac_cl;
1754 G1ParScanPartialArrayClosure* _partial_scan_cl;
1756 int _hash_seed;
1757 uint _queue_num;
1759 size_t _term_attempts;
1761 double _start;
1762 double _start_strong_roots;
1763 double _strong_roots_time;
1764 double _start_term;
1765 double _term_time;
1767 // Map from young-age-index (0 == not young, 1 is youngest) to
1768 // surviving words. base is what we get back from the malloc call
1769 size_t* _surviving_young_words_base;
1770 // this points into the array, as we use the first few entries for padding
1771 size_t* _surviving_young_words;
1773 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1775 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1777 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1779 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1780 CardTableModRefBS* ctbs() { return _ct_bs; }
1782 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1783 if (!from->is_survivor()) {
1784 _g1_rem->par_write_ref(from, p, tid);
1785 }
1786 }
1788 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1789 // If the new value of the field points to the same region or
1790 // is the to-space, we don't need to include it in the Rset updates.
1791 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1792 size_t card_index = ctbs()->index_for(p);
1793 // If the card hasn't been added to the buffer, do it.
1794 if (ctbs()->mark_card_deferred(card_index)) {
1795 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1796 }
1797 }
1798 }
1800 public:
1801 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1803 ~G1ParScanThreadState() {
1804 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1805 }
1807 RefToScanQueue* refs() { return _refs; }
1808 ageTable* age_table() { return &_age_table; }
1810 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1811 return _alloc_buffers[purpose];
1812 }
1814 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1815 size_t undo_waste() const { return _undo_waste; }
1817 #ifdef ASSERT
1818 bool verify_ref(narrowOop* ref) const;
1819 bool verify_ref(oop* ref) const;
1820 bool verify_task(StarTask ref) const;
1821 #endif // ASSERT
1823 template <class T> void push_on_queue(T* ref) {
1824 assert(verify_ref(ref), "sanity");
1825 refs()->push(ref);
1826 }
1828 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1829 if (G1DeferredRSUpdate) {
1830 deferred_rs_update(from, p, tid);
1831 } else {
1832 immediate_rs_update(from, p, tid);
1833 }
1834 }
1836 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1837 HeapWord* obj = NULL;
1838 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1839 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1840 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1841 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1842 alloc_buf->flush_stats_and_retire(_g1h->stats_for_purpose(purpose),
1843 false /* end_of_gc */,
1844 false /* retain */);
1846 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1847 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1848 // Otherwise.
1849 alloc_buf->set_word_size(gclab_word_size);
1850 alloc_buf->set_buf(buf);
1852 obj = alloc_buf->allocate(word_sz);
1853 assert(obj != NULL, "buffer was definitely big enough...");
1854 } else {
1855 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1856 }
1857 return obj;
1858 }
1860 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1861 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1862 if (obj != NULL) return obj;
1863 return allocate_slow(purpose, word_sz);
1864 }
1866 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1867 if (alloc_buffer(purpose)->contains(obj)) {
1868 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1869 "should contain whole object");
1870 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1871 } else {
1872 CollectedHeap::fill_with_object(obj, word_sz);
1873 add_to_undo_waste(word_sz);
1874 }
1875 }
1877 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1878 _evac_failure_cl = evac_failure_cl;
1879 }
1880 OopsInHeapRegionClosure* evac_failure_closure() {
1881 return _evac_failure_cl;
1882 }
1884 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1885 _evac_cl = evac_cl;
1886 }
1888 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1889 _partial_scan_cl = partial_scan_cl;
1890 }
1892 int* hash_seed() { return &_hash_seed; }
1893 uint queue_num() { return _queue_num; }
1895 size_t term_attempts() const { return _term_attempts; }
1896 void note_term_attempt() { _term_attempts++; }
1898 void start_strong_roots() {
1899 _start_strong_roots = os::elapsedTime();
1900 }
1901 void end_strong_roots() {
1902 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1903 }
1904 double strong_roots_time() const { return _strong_roots_time; }
1906 void start_term_time() {
1907 note_term_attempt();
1908 _start_term = os::elapsedTime();
1909 }
1910 void end_term_time() {
1911 _term_time += (os::elapsedTime() - _start_term);
1912 }
1913 double term_time() const { return _term_time; }
1915 double elapsed_time() const {
1916 return os::elapsedTime() - _start;
1917 }
1919 static void
1920 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1921 void
1922 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1924 size_t* surviving_young_words() {
1925 // We add on to hide entry 0 which accumulates surviving words for
1926 // age -1 regions (i.e. non-young ones)
1927 return _surviving_young_words;
1928 }
1930 void retire_alloc_buffers() {
1931 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1932 size_t waste = _alloc_buffers[ap]->words_remaining();
1933 add_to_alloc_buffer_waste(waste);
1934 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1935 true /* end_of_gc */,
1936 false /* retain */);
1937 }
1938 }
1940 template <class T> void deal_with_reference(T* ref_to_scan) {
1941 if (has_partial_array_mask(ref_to_scan)) {
1942 _partial_scan_cl->do_oop_nv(ref_to_scan);
1943 } else {
1944 // Note: we can use "raw" versions of "region_containing" because
1945 // "obj_to_scan" is definitely in the heap, and is not in a
1946 // humongous region.
1947 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1948 _evac_cl->set_region(r);
1949 _evac_cl->do_oop_nv(ref_to_scan);
1950 }
1951 }
1953 void deal_with_reference(StarTask ref) {
1954 assert(verify_task(ref), "sanity");
1955 if (ref.is_narrow()) {
1956 deal_with_reference((narrowOop*)ref);
1957 } else {
1958 deal_with_reference((oop*)ref);
1959 }
1960 }
1962 public:
1963 void trim_queue();
1964 };
1966 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP