Wed, 08 Jun 2011 15:31:51 -0400
7032531: G1: enhance GC logging to include more accurate eden / survivor size transitions
Summary: This changeset extends the logging information generated by +PrintGCDetails to also print out separate size transitions for the eden, survivors, and old regions.
Reviewed-by: ysr, brutisso
1 /*
2 * Copyright (c) 2001, 2011, 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/g1RemSet.hpp"
31 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
32 #include "gc_implementation/g1/heapRegionSets.hpp"
33 #include "gc_implementation/shared/hSpaceCounters.hpp"
34 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
35 #include "memory/barrierSet.hpp"
36 #include "memory/memRegion.hpp"
37 #include "memory/sharedHeap.hpp"
39 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
40 // It uses the "Garbage First" heap organization and algorithm, which
41 // may combine concurrent marking with parallel, incremental compaction of
42 // heap subsets that will yield large amounts of garbage.
44 class HeapRegion;
45 class HeapRegionSeq;
46 class HRRSCleanupTask;
47 class PermanentGenerationSpec;
48 class GenerationSpec;
49 class OopsInHeapRegionClosure;
50 class G1ScanHeapEvacClosure;
51 class ObjectClosure;
52 class SpaceClosure;
53 class CompactibleSpaceClosure;
54 class Space;
55 class G1CollectorPolicy;
56 class GenRemSet;
57 class G1RemSet;
58 class HeapRegionRemSetIterator;
59 class ConcurrentMark;
60 class ConcurrentMarkThread;
61 class ConcurrentG1Refine;
62 class GenerationCounters;
64 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
65 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
67 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
68 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70 enum GCAllocPurpose {
71 GCAllocForTenured,
72 GCAllocForSurvived,
73 GCAllocPurposeCount
74 };
76 class YoungList : public CHeapObj {
77 private:
78 G1CollectedHeap* _g1h;
80 HeapRegion* _head;
82 HeapRegion* _survivor_head;
83 HeapRegion* _survivor_tail;
85 HeapRegion* _curr;
87 size_t _length;
88 size_t _survivor_length;
90 size_t _last_sampled_rs_lengths;
91 size_t _sampled_rs_lengths;
93 void empty_list(HeapRegion* list);
95 public:
96 YoungList(G1CollectedHeap* g1h);
98 void push_region(HeapRegion* hr);
99 void add_survivor_region(HeapRegion* hr);
101 void empty_list();
102 bool is_empty() { return _length == 0; }
103 size_t length() { return _length; }
104 size_t survivor_length() { return _survivor_length; }
106 // Currently we do not keep track of the used byte sum for the
107 // young list and the survivors and it'd be quite a lot of work to
108 // do so. When we'll eventually replace the young list with
109 // instances of HeapRegionLinkedList we'll get that for free. So,
110 // we'll report the more accurate information then.
111 size_t eden_used_bytes() {
112 assert(length() >= survivor_length(), "invariant");
113 return (length() - survivor_length()) * HeapRegion::GrainBytes;
114 }
115 size_t survivor_used_bytes() {
116 return survivor_length() * HeapRegion::GrainBytes;
117 }
119 void rs_length_sampling_init();
120 bool rs_length_sampling_more();
121 void rs_length_sampling_next();
123 void reset_sampled_info() {
124 _last_sampled_rs_lengths = 0;
125 }
126 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128 // for development purposes
129 void reset_auxilary_lists();
130 void clear() { _head = NULL; _length = 0; }
132 void clear_survivors() {
133 _survivor_head = NULL;
134 _survivor_tail = NULL;
135 _survivor_length = 0;
136 }
138 HeapRegion* first_region() { return _head; }
139 HeapRegion* first_survivor_region() { return _survivor_head; }
140 HeapRegion* last_survivor_region() { return _survivor_tail; }
142 // debugging
143 bool check_list_well_formed();
144 bool check_list_empty(bool check_sample = true);
145 void print();
146 };
148 class MutatorAllocRegion : public G1AllocRegion {
149 protected:
150 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
151 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
152 public:
153 MutatorAllocRegion()
154 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
155 };
157 class RefineCardTableEntryClosure;
158 class G1CollectedHeap : public SharedHeap {
159 friend class VM_G1CollectForAllocation;
160 friend class VM_GenCollectForPermanentAllocation;
161 friend class VM_G1CollectFull;
162 friend class VM_G1IncCollectionPause;
163 friend class VMStructs;
164 friend class MutatorAllocRegion;
166 // Closures used in implementation.
167 friend class G1ParCopyHelper;
168 friend class G1IsAliveClosure;
169 friend class G1EvacuateFollowersClosure;
170 friend class G1ParScanThreadState;
171 friend class G1ParScanClosureSuper;
172 friend class G1ParEvacuateFollowersClosure;
173 friend class G1ParTask;
174 friend class G1FreeGarbageRegionClosure;
175 friend class RefineCardTableEntryClosure;
176 friend class G1PrepareCompactClosure;
177 friend class RegionSorter;
178 friend class RegionResetter;
179 friend class CountRCClosure;
180 friend class EvacPopObjClosure;
181 friend class G1ParCleanupCTTask;
183 // Other related classes.
184 friend class G1MarkSweep;
186 private:
187 // The one and only G1CollectedHeap, so static functions can find it.
188 static G1CollectedHeap* _g1h;
190 static size_t _humongous_object_threshold_in_words;
192 // Storage for the G1 heap (excludes the permanent generation).
193 VirtualSpace _g1_storage;
194 MemRegion _g1_reserved;
196 // The part of _g1_storage that is currently committed.
197 MemRegion _g1_committed;
199 // The maximum part of _g1_storage that has ever been committed.
200 MemRegion _g1_max_committed;
202 // The master free list. It will satisfy all new region allocations.
203 MasterFreeRegionList _free_list;
205 // The secondary free list which contains regions that have been
206 // freed up during the cleanup process. This will be appended to the
207 // master free list when appropriate.
208 SecondaryFreeRegionList _secondary_free_list;
210 // It keeps track of the humongous regions.
211 MasterHumongousRegionSet _humongous_set;
213 // The number of regions we could create by expansion.
214 size_t _expansion_regions;
216 // The block offset table for the G1 heap.
217 G1BlockOffsetSharedArray* _bot_shared;
219 // Move all of the regions off the free lists, then rebuild those free
220 // lists, before and after full GC.
221 void tear_down_region_lists();
222 void rebuild_region_lists();
224 // The sequence of all heap regions in the heap.
225 HeapRegionSeq* _hrs;
227 // Alloc region used to satisfy mutator allocation requests.
228 MutatorAllocRegion _mutator_alloc_region;
230 // It resets the mutator alloc region before new allocations can take place.
231 void init_mutator_alloc_region();
233 // It releases the mutator alloc region.
234 void release_mutator_alloc_region();
236 void abandon_gc_alloc_regions();
238 // The to-space memory regions into which objects are being copied during
239 // a GC.
240 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
241 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
242 // These are the regions, one per GCAllocPurpose, that are half-full
243 // at the end of a collection and that we want to reuse during the
244 // next collection.
245 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
246 // This specifies whether we will keep the last half-full region at
247 // the end of a collection so that it can be reused during the next
248 // collection (this is specified per GCAllocPurpose)
249 bool _retain_gc_alloc_region[GCAllocPurposeCount];
251 // A list of the regions that have been set to be alloc regions in the
252 // current collection.
253 HeapRegion* _gc_alloc_region_list;
255 // Helper for monitoring and management support.
256 G1MonitoringSupport* _g1mm;
258 // Determines PLAB size for a particular allocation purpose.
259 static size_t desired_plab_sz(GCAllocPurpose purpose);
261 // When called by par thread, requires the FreeList_lock to be held.
262 void push_gc_alloc_region(HeapRegion* hr);
264 // This should only be called single-threaded. Undeclares all GC alloc
265 // regions.
266 void forget_alloc_region_list();
268 // Should be used to set an alloc region, because there's other
269 // associated bookkeeping.
270 void set_gc_alloc_region(int purpose, HeapRegion* r);
272 // Check well-formedness of alloc region list.
273 bool check_gc_alloc_regions();
275 // Outside of GC pauses, the number of bytes used in all regions other
276 // than the current allocation region.
277 size_t _summary_bytes_used;
279 // This is used for a quick test on whether a reference points into
280 // the collection set or not. Basically, we have an array, with one
281 // byte per region, and that byte denotes whether the corresponding
282 // region is in the collection set or not. The entry corresponding
283 // the bottom of the heap, i.e., region 0, is pointed to by
284 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
285 // biased so that it actually points to address 0 of the address
286 // space, to make the test as fast as possible (we can simply shift
287 // the address to address into it, instead of having to subtract the
288 // bottom of the heap from the address before shifting it; basically
289 // it works in the same way the card table works).
290 bool* _in_cset_fast_test;
292 // The allocated array used for the fast test on whether a reference
293 // points into the collection set or not. This field is also used to
294 // free the array.
295 bool* _in_cset_fast_test_base;
297 // The length of the _in_cset_fast_test_base array.
298 size_t _in_cset_fast_test_length;
300 volatile unsigned _gc_time_stamp;
302 size_t* _surviving_young_words;
304 void setup_surviving_young_words();
305 void update_surviving_young_words(size_t* surv_young_words);
306 void cleanup_surviving_young_words();
308 // It decides whether an explicit GC should start a concurrent cycle
309 // instead of doing a STW GC. Currently, a concurrent cycle is
310 // explicitly started if:
311 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
312 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
313 bool should_do_concurrent_full_gc(GCCause::Cause cause);
315 // Keeps track of how many "full collections" (i.e., Full GCs or
316 // concurrent cycles) we have completed. The number of them we have
317 // started is maintained in _total_full_collections in CollectedHeap.
318 volatile unsigned int _full_collections_completed;
320 // This is a non-product method that is helpful for testing. It is
321 // called at the end of a GC and artificially expands the heap by
322 // allocating a number of dead regions. This way we can induce very
323 // frequent marking cycles and stress the cleanup / concurrent
324 // cleanup code more (as all the regions that will be allocated by
325 // this method will be found dead by the marking cycle).
326 void allocate_dummy_regions() PRODUCT_RETURN;
328 // These are macros so that, if the assert fires, we get the correct
329 // line number, file, etc.
331 #define heap_locking_asserts_err_msg(_extra_message_) \
332 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
333 (_extra_message_), \
334 BOOL_TO_STR(Heap_lock->owned_by_self()), \
335 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
336 BOOL_TO_STR(Thread::current()->is_VM_thread()))
338 #define assert_heap_locked() \
339 do { \
340 assert(Heap_lock->owned_by_self(), \
341 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
342 } while (0)
344 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
345 do { \
346 assert(Heap_lock->owned_by_self() || \
347 (SafepointSynchronize::is_at_safepoint() && \
348 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
349 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
350 "should be at a safepoint")); \
351 } while (0)
353 #define assert_heap_locked_and_not_at_safepoint() \
354 do { \
355 assert(Heap_lock->owned_by_self() && \
356 !SafepointSynchronize::is_at_safepoint(), \
357 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
358 "should not be at a safepoint")); \
359 } while (0)
361 #define assert_heap_not_locked() \
362 do { \
363 assert(!Heap_lock->owned_by_self(), \
364 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
365 } while (0)
367 #define assert_heap_not_locked_and_not_at_safepoint() \
368 do { \
369 assert(!Heap_lock->owned_by_self() && \
370 !SafepointSynchronize::is_at_safepoint(), \
371 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
372 "should not be at a safepoint")); \
373 } while (0)
375 #define assert_at_safepoint(_should_be_vm_thread_) \
376 do { \
377 assert(SafepointSynchronize::is_at_safepoint() && \
378 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
379 heap_locking_asserts_err_msg("should be at a safepoint")); \
380 } while (0)
382 #define assert_not_at_safepoint() \
383 do { \
384 assert(!SafepointSynchronize::is_at_safepoint(), \
385 heap_locking_asserts_err_msg("should not be at a safepoint")); \
386 } while (0)
388 protected:
390 // Returns "true" iff none of the gc alloc regions have any allocations
391 // since the last call to "save_marks".
392 bool all_alloc_regions_no_allocs_since_save_marks();
393 // Perform finalization stuff on all allocation regions.
394 void retire_all_alloc_regions();
396 // The number of regions allocated to hold humongous objects.
397 int _num_humongous_regions;
398 YoungList* _young_list;
400 // The current policy object for the collector.
401 G1CollectorPolicy* _g1_policy;
403 // This is the second level of trying to allocate a new region. If
404 // new_region() didn't find a region on the free_list, this call will
405 // check whether there's anything available on the
406 // secondary_free_list and/or wait for more regions to appear on
407 // that list, if _free_regions_coming is set.
408 HeapRegion* new_region_try_secondary_free_list();
410 // Try to allocate a single non-humongous HeapRegion sufficient for
411 // an allocation of the given word_size. If do_expand is true,
412 // attempt to expand the heap if necessary to satisfy the allocation
413 // request.
414 HeapRegion* new_region(size_t word_size, bool do_expand);
416 // Try to allocate a new region to be used for allocation by
417 // a GC thread. It will try to expand the heap if no region is
418 // available.
419 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
421 // Attempt to satisfy a humongous allocation request of the given
422 // size by finding a contiguous set of free regions of num_regions
423 // length and remove them from the master free list. Return the
424 // index of the first region or -1 if the search was unsuccessful.
425 int humongous_obj_allocate_find_first(size_t num_regions, size_t word_size);
427 // Initialize a contiguous set of free regions of length num_regions
428 // and starting at index first so that they appear as a single
429 // humongous region.
430 HeapWord* humongous_obj_allocate_initialize_regions(int first,
431 size_t num_regions,
432 size_t word_size);
434 // Attempt to allocate a humongous object of the given size. Return
435 // NULL if unsuccessful.
436 HeapWord* humongous_obj_allocate(size_t word_size);
438 // The following two methods, allocate_new_tlab() and
439 // mem_allocate(), are the two main entry points from the runtime
440 // into the G1's allocation routines. They have the following
441 // assumptions:
442 //
443 // * They should both be called outside safepoints.
444 //
445 // * They should both be called without holding the Heap_lock.
446 //
447 // * All allocation requests for new TLABs should go to
448 // allocate_new_tlab().
449 //
450 // * All non-TLAB allocation requests should go to mem_allocate()
451 // and mem_allocate() should never be called with is_tlab == true.
452 //
453 // * If either call cannot satisfy the allocation request using the
454 // current allocating region, they will try to get a new one. If
455 // this fails, they will attempt to do an evacuation pause and
456 // retry the allocation.
457 //
458 // * If all allocation attempts fail, even after trying to schedule
459 // an evacuation pause, allocate_new_tlab() will return NULL,
460 // whereas mem_allocate() will attempt a heap expansion and/or
461 // schedule a Full GC.
462 //
463 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
464 // should never be called with word_size being humongous. All
465 // humongous allocation requests should go to mem_allocate() which
466 // will satisfy them with a special path.
468 virtual HeapWord* allocate_new_tlab(size_t word_size);
470 virtual HeapWord* mem_allocate(size_t word_size,
471 bool is_noref,
472 bool is_tlab, /* expected to be false */
473 bool* gc_overhead_limit_was_exceeded);
475 // The following three methods take a gc_count_before_ret
476 // parameter which is used to return the GC count if the method
477 // returns NULL. Given that we are required to read the GC count
478 // while holding the Heap_lock, and these paths will take the
479 // Heap_lock at some point, it's easier to get them to read the GC
480 // count while holding the Heap_lock before they return NULL instead
481 // of the caller (namely: mem_allocate()) having to also take the
482 // Heap_lock just to read the GC count.
484 // First-level mutator allocation attempt: try to allocate out of
485 // the mutator alloc region without taking the Heap_lock. This
486 // should only be used for non-humongous allocations.
487 inline HeapWord* attempt_allocation(size_t word_size,
488 unsigned int* gc_count_before_ret);
490 // Second-level mutator allocation attempt: take the Heap_lock and
491 // retry the allocation attempt, potentially scheduling a GC
492 // pause. This should only be used for non-humongous allocations.
493 HeapWord* attempt_allocation_slow(size_t word_size,
494 unsigned int* gc_count_before_ret);
496 // Takes the Heap_lock and attempts a humongous allocation. It can
497 // potentially schedule a GC pause.
498 HeapWord* attempt_allocation_humongous(size_t word_size,
499 unsigned int* gc_count_before_ret);
501 // Allocation attempt that should be called during safepoints (e.g.,
502 // at the end of a successful GC). expect_null_mutator_alloc_region
503 // specifies whether the mutator alloc region is expected to be NULL
504 // or not.
505 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
506 bool expect_null_mutator_alloc_region);
508 // It dirties the cards that cover the block so that so that the post
509 // write barrier never queues anything when updating objects on this
510 // block. It is assumed (and in fact we assert) that the block
511 // belongs to a young region.
512 inline void dirty_young_block(HeapWord* start, size_t word_size);
514 // Allocate blocks during garbage collection. Will ensure an
515 // allocation region, either by picking one or expanding the
516 // heap, and then allocate a block of the given size. The block
517 // may not be a humongous - it must fit into a single heap region.
518 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
520 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
521 HeapRegion* alloc_region,
522 bool par,
523 size_t word_size);
525 // Ensure that no further allocations can happen in "r", bearing in mind
526 // that parallel threads might be attempting allocations.
527 void par_allocate_remaining_space(HeapRegion* r);
529 // Retires an allocation region when it is full or at the end of a
530 // GC pause.
531 void retire_alloc_region(HeapRegion* alloc_region, bool par);
533 // These two methods are the "callbacks" from the G1AllocRegion class.
535 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
536 void retire_mutator_alloc_region(HeapRegion* alloc_region,
537 size_t allocated_bytes);
539 // - if explicit_gc is true, the GC is for a System.gc() or a heap
540 // inspection request and should collect the entire heap
541 // - if clear_all_soft_refs is true, all soft references should be
542 // cleared during the GC
543 // - if explicit_gc is false, word_size describes the allocation that
544 // the GC should attempt (at least) to satisfy
545 // - it returns false if it is unable to do the collection due to the
546 // GC locker being active, true otherwise
547 bool do_collection(bool explicit_gc,
548 bool clear_all_soft_refs,
549 size_t word_size);
551 // Callback from VM_G1CollectFull operation.
552 // Perform a full collection.
553 void do_full_collection(bool clear_all_soft_refs);
555 // Resize the heap if necessary after a full collection. If this is
556 // after a collect-for allocation, "word_size" is the allocation size,
557 // and will be considered part of the used portion of the heap.
558 void resize_if_necessary_after_full_collection(size_t word_size);
560 // Callback from VM_G1CollectForAllocation operation.
561 // This function does everything necessary/possible to satisfy a
562 // failed allocation request (including collection, expansion, etc.)
563 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
565 // Attempting to expand the heap sufficiently
566 // to support an allocation of the given "word_size". If
567 // successful, perform the allocation and return the address of the
568 // allocated block, or else "NULL".
569 HeapWord* expand_and_allocate(size_t word_size);
571 public:
573 G1MonitoringSupport* g1mm() { return _g1mm; }
575 // Expand the garbage-first heap by at least the given size (in bytes!).
576 // Returns true if the heap was expanded by the requested amount;
577 // false otherwise.
578 // (Rounds up to a HeapRegion boundary.)
579 bool expand(size_t expand_bytes);
581 // Do anything common to GC's.
582 virtual void gc_prologue(bool full);
583 virtual void gc_epilogue(bool full);
585 // We register a region with the fast "in collection set" test. We
586 // simply set to true the array slot corresponding to this region.
587 void register_region_with_in_cset_fast_test(HeapRegion* r) {
588 assert(_in_cset_fast_test_base != NULL, "sanity");
589 assert(r->in_collection_set(), "invariant");
590 int index = r->hrs_index();
591 assert(0 <= index && (size_t) index < _in_cset_fast_test_length, "invariant");
592 assert(!_in_cset_fast_test_base[index], "invariant");
593 _in_cset_fast_test_base[index] = true;
594 }
596 // This is a fast test on whether a reference points into the
597 // collection set or not. It does not assume that the reference
598 // points into the heap; if it doesn't, it will return false.
599 bool in_cset_fast_test(oop obj) {
600 assert(_in_cset_fast_test != NULL, "sanity");
601 if (_g1_committed.contains((HeapWord*) obj)) {
602 // no need to subtract the bottom of the heap from obj,
603 // _in_cset_fast_test is biased
604 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
605 bool ret = _in_cset_fast_test[index];
606 // let's make sure the result is consistent with what the slower
607 // test returns
608 assert( ret || !obj_in_cs(obj), "sanity");
609 assert(!ret || obj_in_cs(obj), "sanity");
610 return ret;
611 } else {
612 return false;
613 }
614 }
616 void clear_cset_fast_test() {
617 assert(_in_cset_fast_test_base != NULL, "sanity");
618 memset(_in_cset_fast_test_base, false,
619 _in_cset_fast_test_length * sizeof(bool));
620 }
622 // This is called at the end of either a concurrent cycle or a Full
623 // GC to update the number of full collections completed. Those two
624 // can happen in a nested fashion, i.e., we start a concurrent
625 // cycle, a Full GC happens half-way through it which ends first,
626 // and then the cycle notices that a Full GC happened and ends
627 // too. The concurrent parameter is a boolean to help us do a bit
628 // tighter consistency checking in the method. If concurrent is
629 // false, the caller is the inner caller in the nesting (i.e., the
630 // Full GC). If concurrent is true, the caller is the outer caller
631 // in this nesting (i.e., the concurrent cycle). Further nesting is
632 // not currently supported. The end of the this call also notifies
633 // the FullGCCount_lock in case a Java thread is waiting for a full
634 // GC to happen (e.g., it called System.gc() with
635 // +ExplicitGCInvokesConcurrent).
636 void increment_full_collections_completed(bool concurrent);
638 unsigned int full_collections_completed() {
639 return _full_collections_completed;
640 }
642 protected:
644 // Shrink the garbage-first heap by at most the given size (in bytes!).
645 // (Rounds down to a HeapRegion boundary.)
646 virtual void shrink(size_t expand_bytes);
647 void shrink_helper(size_t expand_bytes);
649 #if TASKQUEUE_STATS
650 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
651 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
652 void reset_taskqueue_stats();
653 #endif // TASKQUEUE_STATS
655 // Schedule the VM operation that will do an evacuation pause to
656 // satisfy an allocation request of word_size. *succeeded will
657 // return whether the VM operation was successful (it did do an
658 // evacuation pause) or not (another thread beat us to it or the GC
659 // locker was active). Given that we should not be holding the
660 // Heap_lock when we enter this method, we will pass the
661 // gc_count_before (i.e., total_collections()) as a parameter since
662 // it has to be read while holding the Heap_lock. Currently, both
663 // methods that call do_collection_pause() release the Heap_lock
664 // before the call, so it's easy to read gc_count_before just before.
665 HeapWord* do_collection_pause(size_t word_size,
666 unsigned int gc_count_before,
667 bool* succeeded);
669 // The guts of the incremental collection pause, executed by the vm
670 // thread. It returns false if it is unable to do the collection due
671 // to the GC locker being active, true otherwise
672 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
674 // Actually do the work of evacuating the collection set.
675 void evacuate_collection_set();
677 // The g1 remembered set of the heap.
678 G1RemSet* _g1_rem_set;
679 // And it's mod ref barrier set, used to track updates for the above.
680 ModRefBarrierSet* _mr_bs;
682 // A set of cards that cover the objects for which the Rsets should be updated
683 // concurrently after the collection.
684 DirtyCardQueueSet _dirty_card_queue_set;
686 // The Heap Region Rem Set Iterator.
687 HeapRegionRemSetIterator** _rem_set_iterator;
689 // The closure used to refine a single card.
690 RefineCardTableEntryClosure* _refine_cte_cl;
692 // A function to check the consistency of dirty card logs.
693 void check_ct_logs_at_safepoint();
695 // A DirtyCardQueueSet that is used to hold cards that contain
696 // references into the current collection set. This is used to
697 // update the remembered sets of the regions in the collection
698 // set in the event of an evacuation failure.
699 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
701 // After a collection pause, make the regions in the CS into free
702 // regions.
703 void free_collection_set(HeapRegion* cs_head);
705 // Abandon the current collection set without recording policy
706 // statistics or updating free lists.
707 void abandon_collection_set(HeapRegion* cs_head);
709 // Applies "scan_non_heap_roots" to roots outside the heap,
710 // "scan_rs" to roots inside the heap (having done "set_region" to
711 // indicate the region in which the root resides), and does "scan_perm"
712 // (setting the generation to the perm generation.) If "scan_rs" is
713 // NULL, then this step is skipped. The "worker_i"
714 // param is for use with parallel roots processing, and should be
715 // the "i" of the calling parallel worker thread's work(i) function.
716 // In the sequential case this param will be ignored.
717 void g1_process_strong_roots(bool collecting_perm_gen,
718 SharedHeap::ScanningOption so,
719 OopClosure* scan_non_heap_roots,
720 OopsInHeapRegionClosure* scan_rs,
721 OopsInGenClosure* scan_perm,
722 int worker_i);
724 // Apply "blk" to all the weak roots of the system. These include
725 // JNI weak roots, the code cache, system dictionary, symbol table,
726 // string table, and referents of reachable weak refs.
727 void g1_process_weak_roots(OopClosure* root_closure,
728 OopClosure* non_root_closure);
730 // Invoke "save_marks" on all heap regions.
731 void save_marks();
733 // Frees a non-humongous region by initializing its contents and
734 // adding it to the free list that's passed as a parameter (this is
735 // usually a local list which will be appended to the master free
736 // list later). The used bytes of freed regions are accumulated in
737 // pre_used. If par is true, the region's RSet will not be freed
738 // up. The assumption is that this will be done later.
739 void free_region(HeapRegion* hr,
740 size_t* pre_used,
741 FreeRegionList* free_list,
742 bool par);
744 // Frees a humongous region by collapsing it into individual regions
745 // and calling free_region() for each of them. The freed regions
746 // will be added to the free list that's passed as a parameter (this
747 // is usually a local list which will be appended to the master free
748 // list later). The used bytes of freed regions are accumulated in
749 // pre_used. If par is true, the region's RSet will not be freed
750 // up. The assumption is that this will be done later.
751 void free_humongous_region(HeapRegion* hr,
752 size_t* pre_used,
753 FreeRegionList* free_list,
754 HumongousRegionSet* humongous_proxy_set,
755 bool par);
757 // The concurrent marker (and the thread it runs in.)
758 ConcurrentMark* _cm;
759 ConcurrentMarkThread* _cmThread;
760 bool _mark_in_progress;
762 // The concurrent refiner.
763 ConcurrentG1Refine* _cg1r;
765 // The parallel task queues
766 RefToScanQueueSet *_task_queues;
768 // True iff a evacuation has failed in the current collection.
769 bool _evacuation_failed;
771 // Set the attribute indicating whether evacuation has failed in the
772 // current collection.
773 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
775 // Failed evacuations cause some logical from-space objects to have
776 // forwarding pointers to themselves. Reset them.
777 void remove_self_forwarding_pointers();
779 // When one is non-null, so is the other. Together, they each pair is
780 // an object with a preserved mark, and its mark value.
781 GrowableArray<oop>* _objs_with_preserved_marks;
782 GrowableArray<markOop>* _preserved_marks_of_objs;
784 // Preserve the mark of "obj", if necessary, in preparation for its mark
785 // word being overwritten with a self-forwarding-pointer.
786 void preserve_mark_if_necessary(oop obj, markOop m);
788 // The stack of evac-failure objects left to be scanned.
789 GrowableArray<oop>* _evac_failure_scan_stack;
790 // The closure to apply to evac-failure objects.
792 OopsInHeapRegionClosure* _evac_failure_closure;
793 // Set the field above.
794 void
795 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
796 _evac_failure_closure = evac_failure_closure;
797 }
799 // Push "obj" on the scan stack.
800 void push_on_evac_failure_scan_stack(oop obj);
801 // Process scan stack entries until the stack is empty.
802 void drain_evac_failure_scan_stack();
803 // True iff an invocation of "drain_scan_stack" is in progress; to
804 // prevent unnecessary recursion.
805 bool _drain_in_progress;
807 // Do any necessary initialization for evacuation-failure handling.
808 // "cl" is the closure that will be used to process evac-failure
809 // objects.
810 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
811 // Do any necessary cleanup for evacuation-failure handling data
812 // structures.
813 void finalize_for_evac_failure();
815 // An attempt to evacuate "obj" has failed; take necessary steps.
816 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
817 void handle_evacuation_failure_common(oop obj, markOop m);
820 // Ensure that the relevant gc_alloc regions are set.
821 void get_gc_alloc_regions();
822 // We're done with GC alloc regions. We are going to tear down the
823 // gc alloc list and remove the gc alloc tag from all the regions on
824 // that list. However, we will also retain the last (i.e., the one
825 // that is half-full) GC alloc region, per GCAllocPurpose, for
826 // possible reuse during the next collection, provided
827 // _retain_gc_alloc_region[] indicates that it should be the
828 // case. Said regions are kept in the _retained_gc_alloc_regions[]
829 // array. If the parameter totally is set, we will not retain any
830 // regions, irrespective of what _retain_gc_alloc_region[]
831 // indicates.
832 void release_gc_alloc_regions(bool totally);
833 #ifndef PRODUCT
834 // Useful for debugging.
835 void print_gc_alloc_regions();
836 #endif // !PRODUCT
838 // Instance of the concurrent mark is_alive closure for embedding
839 // into the reference processor as the is_alive_non_header. This
840 // prevents unnecessary additions to the discovered lists during
841 // concurrent discovery.
842 G1CMIsAliveClosure _is_alive_closure;
844 // ("Weak") Reference processing support
845 ReferenceProcessor* _ref_processor;
847 enum G1H_process_strong_roots_tasks {
848 G1H_PS_mark_stack_oops_do,
849 G1H_PS_refProcessor_oops_do,
850 // Leave this one last.
851 G1H_PS_NumElements
852 };
854 SubTasksDone* _process_strong_tasks;
856 volatile bool _free_regions_coming;
858 public:
860 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
862 void set_refine_cte_cl_concurrency(bool concurrent);
864 RefToScanQueue *task_queue(int i) const;
866 // A set of cards where updates happened during the GC
867 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
869 // A DirtyCardQueueSet that is used to hold cards that contain
870 // references into the current collection set. This is used to
871 // update the remembered sets of the regions in the collection
872 // set in the event of an evacuation failure.
873 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
874 { return _into_cset_dirty_card_queue_set; }
876 // Create a G1CollectedHeap with the specified policy.
877 // Must call the initialize method afterwards.
878 // May not return if something goes wrong.
879 G1CollectedHeap(G1CollectorPolicy* policy);
881 // Initialize the G1CollectedHeap to have the initial and
882 // maximum sizes, permanent generation, and remembered and barrier sets
883 // specified by the policy object.
884 jint initialize();
886 virtual void ref_processing_init();
888 void set_par_threads(int t) {
889 SharedHeap::set_par_threads(t);
890 _process_strong_tasks->set_n_threads(t);
891 }
893 virtual CollectedHeap::Name kind() const {
894 return CollectedHeap::G1CollectedHeap;
895 }
897 // The current policy object for the collector.
898 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
900 // Adaptive size policy. No such thing for g1.
901 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
903 // The rem set and barrier set.
904 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
905 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
907 // The rem set iterator.
908 HeapRegionRemSetIterator* rem_set_iterator(int i) {
909 return _rem_set_iterator[i];
910 }
912 HeapRegionRemSetIterator* rem_set_iterator() {
913 return _rem_set_iterator[0];
914 }
916 unsigned get_gc_time_stamp() {
917 return _gc_time_stamp;
918 }
920 void reset_gc_time_stamp() {
921 _gc_time_stamp = 0;
922 OrderAccess::fence();
923 }
925 void increment_gc_time_stamp() {
926 ++_gc_time_stamp;
927 OrderAccess::fence();
928 }
930 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
931 DirtyCardQueue* into_cset_dcq,
932 bool concurrent, int worker_i);
934 // The shared block offset table array.
935 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
937 // Reference Processing accessor
938 ReferenceProcessor* ref_processor() { return _ref_processor; }
940 virtual size_t capacity() const;
941 virtual size_t used() const;
942 // This should be called when we're not holding the heap lock. The
943 // result might be a bit inaccurate.
944 size_t used_unlocked() const;
945 size_t recalculate_used() const;
946 #ifndef PRODUCT
947 size_t recalculate_used_regions() const;
948 #endif // PRODUCT
950 // These virtual functions do the actual allocation.
951 // Some heaps may offer a contiguous region for shared non-blocking
952 // allocation, via inlined code (by exporting the address of the top and
953 // end fields defining the extent of the contiguous allocation region.)
954 // But G1CollectedHeap doesn't yet support this.
956 // Return an estimate of the maximum allocation that could be performed
957 // without triggering any collection or expansion activity. In a
958 // generational collector, for example, this is probably the largest
959 // allocation that could be supported (without expansion) in the youngest
960 // generation. It is "unsafe" because no locks are taken; the result
961 // should be treated as an approximation, not a guarantee, for use in
962 // heuristic resizing decisions.
963 virtual size_t unsafe_max_alloc();
965 virtual bool is_maximal_no_gc() const {
966 return _g1_storage.uncommitted_size() == 0;
967 }
969 // The total number of regions in the heap.
970 size_t n_regions();
972 // The number of regions that are completely free.
973 size_t max_regions();
975 // The number of regions that are completely free.
976 size_t free_regions() {
977 return _free_list.length();
978 }
980 // The number of regions that are not completely free.
981 size_t used_regions() { return n_regions() - free_regions(); }
983 // The number of regions available for "regular" expansion.
984 size_t expansion_regions() { return _expansion_regions; }
986 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
987 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
988 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
989 void verify_dirty_young_regions() PRODUCT_RETURN;
991 // verify_region_sets() performs verification over the region
992 // lists. It will be compiled in the product code to be used when
993 // necessary (i.e., during heap verification).
994 void verify_region_sets();
996 // verify_region_sets_optional() is planted in the code for
997 // list verification in non-product builds (and it can be enabled in
998 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
999 #if HEAP_REGION_SET_FORCE_VERIFY
1000 void verify_region_sets_optional() {
1001 verify_region_sets();
1002 }
1003 #else // HEAP_REGION_SET_FORCE_VERIFY
1004 void verify_region_sets_optional() { }
1005 #endif // HEAP_REGION_SET_FORCE_VERIFY
1007 #ifdef ASSERT
1008 bool is_on_master_free_list(HeapRegion* hr) {
1009 return hr->containing_set() == &_free_list;
1010 }
1012 bool is_in_humongous_set(HeapRegion* hr) {
1013 return hr->containing_set() == &_humongous_set;
1014 }
1015 #endif // ASSERT
1017 // Wrapper for the region list operations that can be called from
1018 // methods outside this class.
1020 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1021 _secondary_free_list.add_as_tail(list);
1022 }
1024 void append_secondary_free_list() {
1025 _free_list.add_as_head(&_secondary_free_list);
1026 }
1028 void append_secondary_free_list_if_not_empty_with_lock() {
1029 // If the secondary free list looks empty there's no reason to
1030 // take the lock and then try to append it.
1031 if (!_secondary_free_list.is_empty()) {
1032 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1033 append_secondary_free_list();
1034 }
1035 }
1037 void set_free_regions_coming();
1038 void reset_free_regions_coming();
1039 bool free_regions_coming() { return _free_regions_coming; }
1040 void wait_while_free_regions_coming();
1042 // Perform a collection of the heap; intended for use in implementing
1043 // "System.gc". This probably implies as full a collection as the
1044 // "CollectedHeap" supports.
1045 virtual void collect(GCCause::Cause cause);
1047 // The same as above but assume that the caller holds the Heap_lock.
1048 void collect_locked(GCCause::Cause cause);
1050 // This interface assumes that it's being called by the
1051 // vm thread. It collects the heap assuming that the
1052 // heap lock is already held and that we are executing in
1053 // the context of the vm thread.
1054 virtual void collect_as_vm_thread(GCCause::Cause cause);
1056 // True iff a evacuation has failed in the most-recent collection.
1057 bool evacuation_failed() { return _evacuation_failed; }
1059 // It will free a region if it has allocated objects in it that are
1060 // all dead. It calls either free_region() or
1061 // free_humongous_region() depending on the type of the region that
1062 // is passed to it.
1063 void free_region_if_empty(HeapRegion* hr,
1064 size_t* pre_used,
1065 FreeRegionList* free_list,
1066 HumongousRegionSet* humongous_proxy_set,
1067 HRRSCleanupTask* hrrs_cleanup_task,
1068 bool par);
1070 // It appends the free list to the master free list and updates the
1071 // master humongous list according to the contents of the proxy
1072 // list. It also adjusts the total used bytes according to pre_used
1073 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1074 void update_sets_after_freeing_regions(size_t pre_used,
1075 FreeRegionList* free_list,
1076 HumongousRegionSet* humongous_proxy_set,
1077 bool par);
1079 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1080 virtual bool is_in(const void* p) const;
1082 // Return "TRUE" iff the given object address is within the collection
1083 // set.
1084 inline bool obj_in_cs(oop obj);
1086 // Return "TRUE" iff the given object address is in the reserved
1087 // region of g1 (excluding the permanent generation).
1088 bool is_in_g1_reserved(const void* p) const {
1089 return _g1_reserved.contains(p);
1090 }
1092 // Returns a MemRegion that corresponds to the space that has been
1093 // reserved for the heap
1094 MemRegion g1_reserved() {
1095 return _g1_reserved;
1096 }
1098 // Returns a MemRegion that corresponds to the space that has been
1099 // committed in the heap
1100 MemRegion g1_committed() {
1101 return _g1_committed;
1102 }
1104 virtual bool is_in_closed_subset(const void* p) const;
1106 // Dirty card table entries covering a list of young regions.
1107 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1109 // This resets the card table to all zeros. It is used after
1110 // a collection pause which used the card table to claim cards.
1111 void cleanUpCardTable();
1113 // Iteration functions.
1115 // Iterate over all the ref-containing fields of all objects, calling
1116 // "cl.do_oop" on each.
1117 virtual void oop_iterate(OopClosure* cl) {
1118 oop_iterate(cl, true);
1119 }
1120 void oop_iterate(OopClosure* cl, bool do_perm);
1122 // Same as above, restricted to a memory region.
1123 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1124 oop_iterate(mr, cl, true);
1125 }
1126 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1128 // Iterate over all objects, calling "cl.do_object" on each.
1129 virtual void object_iterate(ObjectClosure* cl) {
1130 object_iterate(cl, true);
1131 }
1132 virtual void safe_object_iterate(ObjectClosure* cl) {
1133 object_iterate(cl, true);
1134 }
1135 void object_iterate(ObjectClosure* cl, bool do_perm);
1137 // Iterate over all objects allocated since the last collection, calling
1138 // "cl.do_object" on each. The heap must have been initialized properly
1139 // to support this function, or else this call will fail.
1140 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1142 // Iterate over all spaces in use in the heap, in ascending address order.
1143 virtual void space_iterate(SpaceClosure* cl);
1145 // Iterate over heap regions, in address order, terminating the
1146 // iteration early if the "doHeapRegion" method returns "true".
1147 void heap_region_iterate(HeapRegionClosure* blk);
1149 // Iterate over heap regions starting with r (or the first region if "r"
1150 // is NULL), in address order, terminating early if the "doHeapRegion"
1151 // method returns "true".
1152 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk);
1154 // As above but starting from the region at index idx.
1155 void heap_region_iterate_from(int idx, HeapRegionClosure* blk);
1157 HeapRegion* region_at(size_t idx);
1159 // Divide the heap region sequence into "chunks" of some size (the number
1160 // of regions divided by the number of parallel threads times some
1161 // overpartition factor, currently 4). Assumes that this will be called
1162 // in parallel by ParallelGCThreads worker threads with discinct worker
1163 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1164 // calls will use the same "claim_value", and that that claim value is
1165 // different from the claim_value of any heap region before the start of
1166 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1167 // attempting to claim the first region in each chunk, and, if
1168 // successful, applying the closure to each region in the chunk (and
1169 // setting the claim value of the second and subsequent regions of the
1170 // chunk.) For now requires that "doHeapRegion" always returns "false",
1171 // i.e., that a closure never attempt to abort a traversal.
1172 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1173 int worker,
1174 jint claim_value);
1176 // It resets all the region claim values to the default.
1177 void reset_heap_region_claim_values();
1179 #ifdef ASSERT
1180 bool check_heap_region_claim_values(jint claim_value);
1181 #endif // ASSERT
1183 // Iterate over the regions (if any) in the current collection set.
1184 void collection_set_iterate(HeapRegionClosure* blk);
1186 // As above but starting from region r
1187 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1189 // Returns the first (lowest address) compactible space in the heap.
1190 virtual CompactibleSpace* first_compactible_space();
1192 // A CollectedHeap will contain some number of spaces. This finds the
1193 // space containing a given address, or else returns NULL.
1194 virtual Space* space_containing(const void* addr) const;
1196 // A G1CollectedHeap will contain some number of heap regions. This
1197 // finds the region containing a given address, or else returns NULL.
1198 HeapRegion* heap_region_containing(const void* addr) const;
1200 // Like the above, but requires "addr" to be in the heap (to avoid a
1201 // null-check), and unlike the above, may return an continuing humongous
1202 // region.
1203 HeapRegion* heap_region_containing_raw(const void* addr) const;
1205 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1206 // each address in the (reserved) heap is a member of exactly
1207 // one block. The defining characteristic of a block is that it is
1208 // possible to find its size, and thus to progress forward to the next
1209 // block. (Blocks may be of different sizes.) Thus, blocks may
1210 // represent Java objects, or they might be free blocks in a
1211 // free-list-based heap (or subheap), as long as the two kinds are
1212 // distinguishable and the size of each is determinable.
1214 // Returns the address of the start of the "block" that contains the
1215 // address "addr". We say "blocks" instead of "object" since some heaps
1216 // may not pack objects densely; a chunk may either be an object or a
1217 // non-object.
1218 virtual HeapWord* block_start(const void* addr) const;
1220 // Requires "addr" to be the start of a chunk, and returns its size.
1221 // "addr + size" is required to be the start of a new chunk, or the end
1222 // of the active area of the heap.
1223 virtual size_t block_size(const HeapWord* addr) const;
1225 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1226 // the block is an object.
1227 virtual bool block_is_obj(const HeapWord* addr) const;
1229 // Does this heap support heap inspection? (+PrintClassHistogram)
1230 virtual bool supports_heap_inspection() const { return true; }
1232 // Section on thread-local allocation buffers (TLABs)
1233 // See CollectedHeap for semantics.
1235 virtual bool supports_tlab_allocation() const;
1236 virtual size_t tlab_capacity(Thread* thr) const;
1237 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1239 // Can a compiler initialize a new object without store barriers?
1240 // This permission only extends from the creation of a new object
1241 // via a TLAB up to the first subsequent safepoint. If such permission
1242 // is granted for this heap type, the compiler promises to call
1243 // defer_store_barrier() below on any slow path allocation of
1244 // a new object for which such initializing store barriers will
1245 // have been elided. G1, like CMS, allows this, but should be
1246 // ready to provide a compensating write barrier as necessary
1247 // if that storage came out of a non-young region. The efficiency
1248 // of this implementation depends crucially on being able to
1249 // answer very efficiently in constant time whether a piece of
1250 // storage in the heap comes from a young region or not.
1251 // See ReduceInitialCardMarks.
1252 virtual bool can_elide_tlab_store_barriers() const {
1253 // 6920090: Temporarily disabled, because of lingering
1254 // instabilities related to RICM with G1. In the
1255 // interim, the option ReduceInitialCardMarksForG1
1256 // below is left solely as a debugging device at least
1257 // until 6920109 fixes the instabilities.
1258 return ReduceInitialCardMarksForG1;
1259 }
1261 virtual bool card_mark_must_follow_store() const {
1262 return true;
1263 }
1265 bool is_in_young(oop obj) {
1266 HeapRegion* hr = heap_region_containing(obj);
1267 return hr != NULL && hr->is_young();
1268 }
1270 #ifdef ASSERT
1271 virtual bool is_in_partial_collection(const void* p);
1272 #endif
1274 virtual bool is_scavengable(const void* addr);
1276 // We don't need barriers for initializing stores to objects
1277 // in the young gen: for the SATB pre-barrier, there is no
1278 // pre-value that needs to be remembered; for the remembered-set
1279 // update logging post-barrier, we don't maintain remembered set
1280 // information for young gen objects. Note that non-generational
1281 // G1 does not have any "young" objects, should not elide
1282 // the rs logging barrier and so should always answer false below.
1283 // However, non-generational G1 (-XX:-G1Gen) appears to have
1284 // bit-rotted so was not tested below.
1285 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1286 // Re 6920090, 6920109 above.
1287 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1288 assert(G1Gen || !is_in_young(new_obj),
1289 "Non-generational G1 should never return true below");
1290 return is_in_young(new_obj);
1291 }
1293 // Can a compiler elide a store barrier when it writes
1294 // a permanent oop into the heap? Applies when the compiler
1295 // is storing x to the heap, where x->is_perm() is true.
1296 virtual bool can_elide_permanent_oop_store_barriers() const {
1297 // At least until perm gen collection is also G1-ified, at
1298 // which point this should return false.
1299 return true;
1300 }
1302 // The boundary between a "large" and "small" array of primitives, in
1303 // words.
1304 virtual size_t large_typearray_limit();
1306 // Returns "true" iff the given word_size is "very large".
1307 static bool isHumongous(size_t word_size) {
1308 // Note this has to be strictly greater-than as the TLABs
1309 // are capped at the humongous thresold and we want to
1310 // ensure that we don't try to allocate a TLAB as
1311 // humongous and that we don't allocate a humongous
1312 // object in a TLAB.
1313 return word_size > _humongous_object_threshold_in_words;
1314 }
1316 // Update mod union table with the set of dirty cards.
1317 void updateModUnion();
1319 // Set the mod union bits corresponding to the given memRegion. Note
1320 // that this is always a safe operation, since it doesn't clear any
1321 // bits.
1322 void markModUnionRange(MemRegion mr);
1324 // Records the fact that a marking phase is no longer in progress.
1325 void set_marking_complete() {
1326 _mark_in_progress = false;
1327 }
1328 void set_marking_started() {
1329 _mark_in_progress = true;
1330 }
1331 bool mark_in_progress() {
1332 return _mark_in_progress;
1333 }
1335 // Print the maximum heap capacity.
1336 virtual size_t max_capacity() const;
1338 virtual jlong millis_since_last_gc();
1340 // Perform any cleanup actions necessary before allowing a verification.
1341 virtual void prepare_for_verify();
1343 // Perform verification.
1345 // use_prev_marking == true -> use "prev" marking information,
1346 // use_prev_marking == false -> use "next" marking information
1347 // NOTE: Only the "prev" marking information is guaranteed to be
1348 // consistent most of the time, so most calls to this should use
1349 // use_prev_marking == true. Currently, there is only one case where
1350 // this is called with use_prev_marking == false, which is to verify
1351 // the "next" marking information at the end of remark.
1352 void verify(bool allow_dirty, bool silent, bool use_prev_marking);
1354 // Override; it uses the "prev" marking information
1355 virtual void verify(bool allow_dirty, bool silent);
1356 // Default behavior by calling print(tty);
1357 virtual void print() const;
1358 // This calls print_on(st, PrintHeapAtGCExtended).
1359 virtual void print_on(outputStream* st) const;
1360 // If extended is true, it will print out information for all
1361 // regions in the heap by calling print_on_extended(st).
1362 virtual void print_on(outputStream* st, bool extended) const;
1363 virtual void print_on_extended(outputStream* st) const;
1365 virtual void print_gc_threads_on(outputStream* st) const;
1366 virtual void gc_threads_do(ThreadClosure* tc) const;
1368 // Override
1369 void print_tracing_info() const;
1371 // If "addr" is a pointer into the (reserved?) heap, returns a positive
1372 // number indicating the "arena" within the heap in which "addr" falls.
1373 // Or else returns 0.
1374 virtual int addr_to_arena_id(void* addr) const;
1376 // Convenience function to be used in situations where the heap type can be
1377 // asserted to be this type.
1378 static G1CollectedHeap* heap();
1380 void empty_young_list();
1382 void set_region_short_lived_locked(HeapRegion* hr);
1383 // add appropriate methods for any other surv rate groups
1385 YoungList* young_list() { return _young_list; }
1387 // debugging
1388 bool check_young_list_well_formed() {
1389 return _young_list->check_list_well_formed();
1390 }
1392 bool check_young_list_empty(bool check_heap,
1393 bool check_sample = true);
1395 // *** Stuff related to concurrent marking. It's not clear to me that so
1396 // many of these need to be public.
1398 // The functions below are helper functions that a subclass of
1399 // "CollectedHeap" can use in the implementation of its virtual
1400 // functions.
1401 // This performs a concurrent marking of the live objects in a
1402 // bitmap off to the side.
1403 void doConcurrentMark();
1405 // This is called from the marksweep collector which then does
1406 // a concurrent mark and verifies that the results agree with
1407 // the stop the world marking.
1408 void checkConcurrentMark();
1409 void do_sync_mark();
1411 bool isMarkedPrev(oop obj) const;
1412 bool isMarkedNext(oop obj) const;
1414 // use_prev_marking == true -> use "prev" marking information,
1415 // use_prev_marking == false -> use "next" marking information
1416 bool is_obj_dead_cond(const oop obj,
1417 const HeapRegion* hr,
1418 const bool use_prev_marking) const {
1419 if (use_prev_marking) {
1420 return is_obj_dead(obj, hr);
1421 } else {
1422 return is_obj_ill(obj, hr);
1423 }
1424 }
1426 // Determine if an object is dead, given the object and also
1427 // the region to which the object belongs. An object is dead
1428 // iff a) it was not allocated since the last mark and b) it
1429 // is not marked.
1431 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1432 return
1433 !hr->obj_allocated_since_prev_marking(obj) &&
1434 !isMarkedPrev(obj);
1435 }
1437 // This is used when copying an object to survivor space.
1438 // If the object is marked live, then we mark the copy live.
1439 // If the object is allocated since the start of this mark
1440 // cycle, then we mark the copy live.
1441 // If the object has been around since the previous mark
1442 // phase, and hasn't been marked yet during this phase,
1443 // then we don't mark it, we just wait for the
1444 // current marking cycle to get to it.
1446 // This function returns true when an object has been
1447 // around since the previous marking and hasn't yet
1448 // been marked during this marking.
1450 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1451 return
1452 !hr->obj_allocated_since_next_marking(obj) &&
1453 !isMarkedNext(obj);
1454 }
1456 // Determine if an object is dead, given only the object itself.
1457 // This will find the region to which the object belongs and
1458 // then call the region version of the same function.
1460 // Added if it is in permanent gen it isn't dead.
1461 // Added if it is NULL it isn't dead.
1463 // use_prev_marking == true -> use "prev" marking information,
1464 // use_prev_marking == false -> use "next" marking information
1465 bool is_obj_dead_cond(const oop obj,
1466 const bool use_prev_marking) {
1467 if (use_prev_marking) {
1468 return is_obj_dead(obj);
1469 } else {
1470 return is_obj_ill(obj);
1471 }
1472 }
1474 bool is_obj_dead(const oop obj) {
1475 const HeapRegion* hr = heap_region_containing(obj);
1476 if (hr == NULL) {
1477 if (Universe::heap()->is_in_permanent(obj))
1478 return false;
1479 else if (obj == NULL) return false;
1480 else return true;
1481 }
1482 else return is_obj_dead(obj, hr);
1483 }
1485 bool is_obj_ill(const oop obj) {
1486 const HeapRegion* hr = heap_region_containing(obj);
1487 if (hr == NULL) {
1488 if (Universe::heap()->is_in_permanent(obj))
1489 return false;
1490 else if (obj == NULL) return false;
1491 else return true;
1492 }
1493 else return is_obj_ill(obj, hr);
1494 }
1496 // The following is just to alert the verification code
1497 // that a full collection has occurred and that the
1498 // remembered sets are no longer up to date.
1499 bool _full_collection;
1500 void set_full_collection() { _full_collection = true;}
1501 void clear_full_collection() {_full_collection = false;}
1502 bool full_collection() {return _full_collection;}
1504 ConcurrentMark* concurrent_mark() const { return _cm; }
1505 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1507 // The dirty cards region list is used to record a subset of regions
1508 // whose cards need clearing. The list if populated during the
1509 // remembered set scanning and drained during the card table
1510 // cleanup. Although the methods are reentrant, population/draining
1511 // phases must not overlap. For synchronization purposes the last
1512 // element on the list points to itself.
1513 HeapRegion* _dirty_cards_region_list;
1514 void push_dirty_cards_region(HeapRegion* hr);
1515 HeapRegion* pop_dirty_cards_region();
1517 public:
1518 void stop_conc_gc_threads();
1520 // <NEW PREDICTION>
1522 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1523 void check_if_region_is_too_expensive(double predicted_time_ms);
1524 size_t pending_card_num();
1525 size_t max_pending_card_num();
1526 size_t cards_scanned();
1528 // </NEW PREDICTION>
1530 protected:
1531 size_t _max_heap_capacity;
1532 };
1534 #define use_local_bitmaps 1
1535 #define verify_local_bitmaps 0
1536 #define oop_buffer_length 256
1538 #ifndef PRODUCT
1539 class GCLabBitMap;
1540 class GCLabBitMapClosure: public BitMapClosure {
1541 private:
1542 ConcurrentMark* _cm;
1543 GCLabBitMap* _bitmap;
1545 public:
1546 GCLabBitMapClosure(ConcurrentMark* cm,
1547 GCLabBitMap* bitmap) {
1548 _cm = cm;
1549 _bitmap = bitmap;
1550 }
1552 virtual bool do_bit(size_t offset);
1553 };
1554 #endif // !PRODUCT
1556 class GCLabBitMap: public BitMap {
1557 private:
1558 ConcurrentMark* _cm;
1560 int _shifter;
1561 size_t _bitmap_word_covers_words;
1563 // beginning of the heap
1564 HeapWord* _heap_start;
1566 // this is the actual start of the GCLab
1567 HeapWord* _real_start_word;
1569 // this is the actual end of the GCLab
1570 HeapWord* _real_end_word;
1572 // this is the first word, possibly located before the actual start
1573 // of the GCLab, that corresponds to the first bit of the bitmap
1574 HeapWord* _start_word;
1576 // size of a GCLab in words
1577 size_t _gclab_word_size;
1579 static int shifter() {
1580 return MinObjAlignment - 1;
1581 }
1583 // how many heap words does a single bitmap word corresponds to?
1584 static size_t bitmap_word_covers_words() {
1585 return BitsPerWord << shifter();
1586 }
1588 size_t gclab_word_size() const {
1589 return _gclab_word_size;
1590 }
1592 // Calculates actual GCLab size in words
1593 size_t gclab_real_word_size() const {
1594 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1595 / BitsPerWord;
1596 }
1598 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1599 size_t bits_in_bitmap = gclab_word_size >> shifter();
1600 // We are going to ensure that the beginning of a word in this
1601 // bitmap also corresponds to the beginning of a word in the
1602 // global marking bitmap. To handle the case where a GCLab
1603 // starts from the middle of the bitmap, we need to add enough
1604 // space (i.e. up to a bitmap word) to ensure that we have
1605 // enough bits in the bitmap.
1606 return bits_in_bitmap + BitsPerWord - 1;
1607 }
1608 public:
1609 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1610 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1611 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1612 _shifter(shifter()),
1613 _bitmap_word_covers_words(bitmap_word_covers_words()),
1614 _heap_start(heap_start),
1615 _gclab_word_size(gclab_word_size),
1616 _real_start_word(NULL),
1617 _real_end_word(NULL),
1618 _start_word(NULL)
1619 {
1620 guarantee( size_in_words() >= bitmap_size_in_words(),
1621 "just making sure");
1622 }
1624 inline unsigned heapWordToOffset(HeapWord* addr) {
1625 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1626 assert(offset < size(), "offset should be within bounds");
1627 return offset;
1628 }
1630 inline HeapWord* offsetToHeapWord(size_t offset) {
1631 HeapWord* addr = _start_word + (offset << _shifter);
1632 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1633 return addr;
1634 }
1636 bool fields_well_formed() {
1637 bool ret1 = (_real_start_word == NULL) &&
1638 (_real_end_word == NULL) &&
1639 (_start_word == NULL);
1640 if (ret1)
1641 return true;
1643 bool ret2 = _real_start_word >= _start_word &&
1644 _start_word < _real_end_word &&
1645 (_real_start_word + _gclab_word_size) == _real_end_word &&
1646 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1647 > _real_end_word;
1648 return ret2;
1649 }
1651 inline bool mark(HeapWord* addr) {
1652 guarantee(use_local_bitmaps, "invariant");
1653 assert(fields_well_formed(), "invariant");
1655 if (addr >= _real_start_word && addr < _real_end_word) {
1656 assert(!isMarked(addr), "should not have already been marked");
1658 // first mark it on the bitmap
1659 at_put(heapWordToOffset(addr), true);
1661 return true;
1662 } else {
1663 return false;
1664 }
1665 }
1667 inline bool isMarked(HeapWord* addr) {
1668 guarantee(use_local_bitmaps, "invariant");
1669 assert(fields_well_formed(), "invariant");
1671 return at(heapWordToOffset(addr));
1672 }
1674 void set_buffer(HeapWord* start) {
1675 guarantee(use_local_bitmaps, "invariant");
1676 clear();
1678 assert(start != NULL, "invariant");
1679 _real_start_word = start;
1680 _real_end_word = start + _gclab_word_size;
1682 size_t diff =
1683 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1684 _start_word = start - diff;
1686 assert(fields_well_formed(), "invariant");
1687 }
1689 #ifndef PRODUCT
1690 void verify() {
1691 // verify that the marks have been propagated
1692 GCLabBitMapClosure cl(_cm, this);
1693 iterate(&cl);
1694 }
1695 #endif // PRODUCT
1697 void retire() {
1698 guarantee(use_local_bitmaps, "invariant");
1699 assert(fields_well_formed(), "invariant");
1701 if (_start_word != NULL) {
1702 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1704 // this means that the bitmap was set up for the GCLab
1705 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1707 mark_bitmap->mostly_disjoint_range_union(this,
1708 0, // always start from the start of the bitmap
1709 _start_word,
1710 gclab_real_word_size());
1711 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1713 #ifndef PRODUCT
1714 if (use_local_bitmaps && verify_local_bitmaps)
1715 verify();
1716 #endif // PRODUCT
1717 } else {
1718 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1719 }
1720 }
1722 size_t bitmap_size_in_words() const {
1723 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1724 }
1726 };
1728 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1729 private:
1730 bool _retired;
1731 bool _during_marking;
1732 GCLabBitMap _bitmap;
1734 public:
1735 G1ParGCAllocBuffer(size_t gclab_word_size) :
1736 ParGCAllocBuffer(gclab_word_size),
1737 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1738 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1739 _retired(false)
1740 { }
1742 inline bool mark(HeapWord* addr) {
1743 guarantee(use_local_bitmaps, "invariant");
1744 assert(_during_marking, "invariant");
1745 return _bitmap.mark(addr);
1746 }
1748 inline void set_buf(HeapWord* buf) {
1749 if (use_local_bitmaps && _during_marking)
1750 _bitmap.set_buffer(buf);
1751 ParGCAllocBuffer::set_buf(buf);
1752 _retired = false;
1753 }
1755 inline void retire(bool end_of_gc, bool retain) {
1756 if (_retired)
1757 return;
1758 if (use_local_bitmaps && _during_marking) {
1759 _bitmap.retire();
1760 }
1761 ParGCAllocBuffer::retire(end_of_gc, retain);
1762 _retired = true;
1763 }
1764 };
1766 class G1ParScanThreadState : public StackObj {
1767 protected:
1768 G1CollectedHeap* _g1h;
1769 RefToScanQueue* _refs;
1770 DirtyCardQueue _dcq;
1771 CardTableModRefBS* _ct_bs;
1772 G1RemSet* _g1_rem;
1774 G1ParGCAllocBuffer _surviving_alloc_buffer;
1775 G1ParGCAllocBuffer _tenured_alloc_buffer;
1776 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1777 ageTable _age_table;
1779 size_t _alloc_buffer_waste;
1780 size_t _undo_waste;
1782 OopsInHeapRegionClosure* _evac_failure_cl;
1783 G1ParScanHeapEvacClosure* _evac_cl;
1784 G1ParScanPartialArrayClosure* _partial_scan_cl;
1786 int _hash_seed;
1787 int _queue_num;
1789 size_t _term_attempts;
1791 double _start;
1792 double _start_strong_roots;
1793 double _strong_roots_time;
1794 double _start_term;
1795 double _term_time;
1797 // Map from young-age-index (0 == not young, 1 is youngest) to
1798 // surviving words. base is what we get back from the malloc call
1799 size_t* _surviving_young_words_base;
1800 // this points into the array, as we use the first few entries for padding
1801 size_t* _surviving_young_words;
1803 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1805 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1807 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1809 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1810 CardTableModRefBS* ctbs() { return _ct_bs; }
1812 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1813 if (!from->is_survivor()) {
1814 _g1_rem->par_write_ref(from, p, tid);
1815 }
1816 }
1818 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1819 // If the new value of the field points to the same region or
1820 // is the to-space, we don't need to include it in the Rset updates.
1821 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1822 size_t card_index = ctbs()->index_for(p);
1823 // If the card hasn't been added to the buffer, do it.
1824 if (ctbs()->mark_card_deferred(card_index)) {
1825 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1826 }
1827 }
1828 }
1830 public:
1831 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1833 ~G1ParScanThreadState() {
1834 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1835 }
1837 RefToScanQueue* refs() { return _refs; }
1838 ageTable* age_table() { return &_age_table; }
1840 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1841 return _alloc_buffers[purpose];
1842 }
1844 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1845 size_t undo_waste() const { return _undo_waste; }
1847 #ifdef ASSERT
1848 bool verify_ref(narrowOop* ref) const;
1849 bool verify_ref(oop* ref) const;
1850 bool verify_task(StarTask ref) const;
1851 #endif // ASSERT
1853 template <class T> void push_on_queue(T* ref) {
1854 assert(verify_ref(ref), "sanity");
1855 refs()->push(ref);
1856 }
1858 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1859 if (G1DeferredRSUpdate) {
1860 deferred_rs_update(from, p, tid);
1861 } else {
1862 immediate_rs_update(from, p, tid);
1863 }
1864 }
1866 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1868 HeapWord* obj = NULL;
1869 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1870 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1871 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1872 assert(gclab_word_size == alloc_buf->word_sz(),
1873 "dynamic resizing is not supported");
1874 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1875 alloc_buf->retire(false, false);
1877 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1878 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1879 // Otherwise.
1880 alloc_buf->set_buf(buf);
1882 obj = alloc_buf->allocate(word_sz);
1883 assert(obj != NULL, "buffer was definitely big enough...");
1884 } else {
1885 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1886 }
1887 return obj;
1888 }
1890 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1891 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1892 if (obj != NULL) return obj;
1893 return allocate_slow(purpose, word_sz);
1894 }
1896 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1897 if (alloc_buffer(purpose)->contains(obj)) {
1898 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1899 "should contain whole object");
1900 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1901 } else {
1902 CollectedHeap::fill_with_object(obj, word_sz);
1903 add_to_undo_waste(word_sz);
1904 }
1905 }
1907 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1908 _evac_failure_cl = evac_failure_cl;
1909 }
1910 OopsInHeapRegionClosure* evac_failure_closure() {
1911 return _evac_failure_cl;
1912 }
1914 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1915 _evac_cl = evac_cl;
1916 }
1918 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1919 _partial_scan_cl = partial_scan_cl;
1920 }
1922 int* hash_seed() { return &_hash_seed; }
1923 int queue_num() { return _queue_num; }
1925 size_t term_attempts() const { return _term_attempts; }
1926 void note_term_attempt() { _term_attempts++; }
1928 void start_strong_roots() {
1929 _start_strong_roots = os::elapsedTime();
1930 }
1931 void end_strong_roots() {
1932 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1933 }
1934 double strong_roots_time() const { return _strong_roots_time; }
1936 void start_term_time() {
1937 note_term_attempt();
1938 _start_term = os::elapsedTime();
1939 }
1940 void end_term_time() {
1941 _term_time += (os::elapsedTime() - _start_term);
1942 }
1943 double term_time() const { return _term_time; }
1945 double elapsed_time() const {
1946 return os::elapsedTime() - _start;
1947 }
1949 static void
1950 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1951 void
1952 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1954 size_t* surviving_young_words() {
1955 // We add on to hide entry 0 which accumulates surviving words for
1956 // age -1 regions (i.e. non-young ones)
1957 return _surviving_young_words;
1958 }
1960 void retire_alloc_buffers() {
1961 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1962 size_t waste = _alloc_buffers[ap]->words_remaining();
1963 add_to_alloc_buffer_waste(waste);
1964 _alloc_buffers[ap]->retire(true, false);
1965 }
1966 }
1968 template <class T> void deal_with_reference(T* ref_to_scan) {
1969 if (has_partial_array_mask(ref_to_scan)) {
1970 _partial_scan_cl->do_oop_nv(ref_to_scan);
1971 } else {
1972 // Note: we can use "raw" versions of "region_containing" because
1973 // "obj_to_scan" is definitely in the heap, and is not in a
1974 // humongous region.
1975 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1976 _evac_cl->set_region(r);
1977 _evac_cl->do_oop_nv(ref_to_scan);
1978 }
1979 }
1981 void deal_with_reference(StarTask ref) {
1982 assert(verify_task(ref), "sanity");
1983 if (ref.is_narrow()) {
1984 deal_with_reference((narrowOop*)ref);
1985 } else {
1986 deal_with_reference((oop*)ref);
1987 }
1988 }
1990 public:
1991 void trim_queue();
1992 };
1994 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP