Tue, 21 Aug 2012 14:10:39 -0700
7185699: G1: Prediction model discrepancies
Summary: Correct the result value of G1CollectedHeap::pending_card_num(). Change the code that calculates the GC efficiency of a non-young heap region to use historical data from mixed GCs and the actual number of live bytes when predicting how long it would take to collect the region. Changes were also reviewed by Thomas Schatzl.
Reviewed-by: azeemj, brutisso
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 cards_scanned();
1711 protected:
1712 size_t _max_heap_capacity;
1713 };
1715 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1716 private:
1717 bool _retired;
1719 public:
1720 G1ParGCAllocBuffer(size_t gclab_word_size);
1722 void set_buf(HeapWord* buf) {
1723 ParGCAllocBuffer::set_buf(buf);
1724 _retired = false;
1725 }
1727 void retire(bool end_of_gc, bool retain) {
1728 if (_retired)
1729 return;
1730 ParGCAllocBuffer::retire(end_of_gc, retain);
1731 _retired = true;
1732 }
1733 };
1735 class G1ParScanThreadState : public StackObj {
1736 protected:
1737 G1CollectedHeap* _g1h;
1738 RefToScanQueue* _refs;
1739 DirtyCardQueue _dcq;
1740 CardTableModRefBS* _ct_bs;
1741 G1RemSet* _g1_rem;
1743 G1ParGCAllocBuffer _surviving_alloc_buffer;
1744 G1ParGCAllocBuffer _tenured_alloc_buffer;
1745 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1746 ageTable _age_table;
1748 size_t _alloc_buffer_waste;
1749 size_t _undo_waste;
1751 OopsInHeapRegionClosure* _evac_failure_cl;
1752 G1ParScanHeapEvacClosure* _evac_cl;
1753 G1ParScanPartialArrayClosure* _partial_scan_cl;
1755 int _hash_seed;
1756 uint _queue_num;
1758 size_t _term_attempts;
1760 double _start;
1761 double _start_strong_roots;
1762 double _strong_roots_time;
1763 double _start_term;
1764 double _term_time;
1766 // Map from young-age-index (0 == not young, 1 is youngest) to
1767 // surviving words. base is what we get back from the malloc call
1768 size_t* _surviving_young_words_base;
1769 // this points into the array, as we use the first few entries for padding
1770 size_t* _surviving_young_words;
1772 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1774 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1776 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1778 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1779 CardTableModRefBS* ctbs() { return _ct_bs; }
1781 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1782 if (!from->is_survivor()) {
1783 _g1_rem->par_write_ref(from, p, tid);
1784 }
1785 }
1787 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1788 // If the new value of the field points to the same region or
1789 // is the to-space, we don't need to include it in the Rset updates.
1790 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1791 size_t card_index = ctbs()->index_for(p);
1792 // If the card hasn't been added to the buffer, do it.
1793 if (ctbs()->mark_card_deferred(card_index)) {
1794 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1795 }
1796 }
1797 }
1799 public:
1800 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1802 ~G1ParScanThreadState() {
1803 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1804 }
1806 RefToScanQueue* refs() { return _refs; }
1807 ageTable* age_table() { return &_age_table; }
1809 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1810 return _alloc_buffers[purpose];
1811 }
1813 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1814 size_t undo_waste() const { return _undo_waste; }
1816 #ifdef ASSERT
1817 bool verify_ref(narrowOop* ref) const;
1818 bool verify_ref(oop* ref) const;
1819 bool verify_task(StarTask ref) const;
1820 #endif // ASSERT
1822 template <class T> void push_on_queue(T* ref) {
1823 assert(verify_ref(ref), "sanity");
1824 refs()->push(ref);
1825 }
1827 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1828 if (G1DeferredRSUpdate) {
1829 deferred_rs_update(from, p, tid);
1830 } else {
1831 immediate_rs_update(from, p, tid);
1832 }
1833 }
1835 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1836 HeapWord* obj = NULL;
1837 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1838 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1839 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1840 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1841 alloc_buf->flush_stats_and_retire(_g1h->stats_for_purpose(purpose),
1842 false /* end_of_gc */,
1843 false /* retain */);
1845 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1846 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1847 // Otherwise.
1848 alloc_buf->set_word_size(gclab_word_size);
1849 alloc_buf->set_buf(buf);
1851 obj = alloc_buf->allocate(word_sz);
1852 assert(obj != NULL, "buffer was definitely big enough...");
1853 } else {
1854 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1855 }
1856 return obj;
1857 }
1859 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1860 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1861 if (obj != NULL) return obj;
1862 return allocate_slow(purpose, word_sz);
1863 }
1865 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1866 if (alloc_buffer(purpose)->contains(obj)) {
1867 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1868 "should contain whole object");
1869 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1870 } else {
1871 CollectedHeap::fill_with_object(obj, word_sz);
1872 add_to_undo_waste(word_sz);
1873 }
1874 }
1876 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1877 _evac_failure_cl = evac_failure_cl;
1878 }
1879 OopsInHeapRegionClosure* evac_failure_closure() {
1880 return _evac_failure_cl;
1881 }
1883 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1884 _evac_cl = evac_cl;
1885 }
1887 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1888 _partial_scan_cl = partial_scan_cl;
1889 }
1891 int* hash_seed() { return &_hash_seed; }
1892 uint queue_num() { return _queue_num; }
1894 size_t term_attempts() const { return _term_attempts; }
1895 void note_term_attempt() { _term_attempts++; }
1897 void start_strong_roots() {
1898 _start_strong_roots = os::elapsedTime();
1899 }
1900 void end_strong_roots() {
1901 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1902 }
1903 double strong_roots_time() const { return _strong_roots_time; }
1905 void start_term_time() {
1906 note_term_attempt();
1907 _start_term = os::elapsedTime();
1908 }
1909 void end_term_time() {
1910 _term_time += (os::elapsedTime() - _start_term);
1911 }
1912 double term_time() const { return _term_time; }
1914 double elapsed_time() const {
1915 return os::elapsedTime() - _start;
1916 }
1918 static void
1919 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1920 void
1921 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1923 size_t* surviving_young_words() {
1924 // We add on to hide entry 0 which accumulates surviving words for
1925 // age -1 regions (i.e. non-young ones)
1926 return _surviving_young_words;
1927 }
1929 void retire_alloc_buffers() {
1930 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1931 size_t waste = _alloc_buffers[ap]->words_remaining();
1932 add_to_alloc_buffer_waste(waste);
1933 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1934 true /* end_of_gc */,
1935 false /* retain */);
1936 }
1937 }
1939 template <class T> void deal_with_reference(T* ref_to_scan) {
1940 if (has_partial_array_mask(ref_to_scan)) {
1941 _partial_scan_cl->do_oop_nv(ref_to_scan);
1942 } else {
1943 // Note: we can use "raw" versions of "region_containing" because
1944 // "obj_to_scan" is definitely in the heap, and is not in a
1945 // humongous region.
1946 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1947 _evac_cl->set_region(r);
1948 _evac_cl->do_oop_nv(ref_to_scan);
1949 }
1950 }
1952 void deal_with_reference(StarTask ref) {
1953 assert(verify_task(ref), "sanity");
1954 if (ref.is_narrow()) {
1955 deal_with_reference((narrowOop*)ref);
1956 } else {
1957 deal_with_reference((oop*)ref);
1958 }
1959 }
1961 public:
1962 void trim_queue();
1963 };
1965 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP