Thu, 22 Sep 2011 10:57:37 -0700
6484982: G1: process references during evacuation pauses
Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp
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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12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
65 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> 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 {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 size_t _length;
89 size_t _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 size_t length() { return _length; }
105 size_t 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 (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return 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 friend class G1ParCopyHelper;
203 friend class G1IsAliveClosure;
204 friend class G1EvacuateFollowersClosure;
205 friend class G1ParScanThreadState;
206 friend class G1ParScanClosureSuper;
207 friend class G1ParEvacuateFollowersClosure;
208 friend class G1ParTask;
209 friend class G1FreeGarbageRegionClosure;
210 friend class RefineCardTableEntryClosure;
211 friend class G1PrepareCompactClosure;
212 friend class RegionSorter;
213 friend class RegionResetter;
214 friend class CountRCClosure;
215 friend class EvacPopObjClosure;
216 friend class G1ParCleanupCTTask;
218 // Other related classes.
219 friend class G1MarkSweep;
221 private:
222 // The one and only G1CollectedHeap, so static functions can find it.
223 static G1CollectedHeap* _g1h;
225 static size_t _humongous_object_threshold_in_words;
227 // Storage for the G1 heap (excludes the permanent generation).
228 VirtualSpace _g1_storage;
229 MemRegion _g1_reserved;
231 // The part of _g1_storage that is currently committed.
232 MemRegion _g1_committed;
234 // The master free list. It will satisfy all new region allocations.
235 MasterFreeRegionList _free_list;
237 // The secondary free list which contains regions that have been
238 // freed up during the cleanup process. This will be appended to the
239 // master free list when appropriate.
240 SecondaryFreeRegionList _secondary_free_list;
242 // It keeps track of the humongous regions.
243 MasterHumongousRegionSet _humongous_set;
245 // The number of regions we could create by expansion.
246 size_t _expansion_regions;
248 // The block offset table for the G1 heap.
249 G1BlockOffsetSharedArray* _bot_shared;
251 // Move all of the regions off the free lists, then rebuild those free
252 // lists, before and after full GC.
253 void tear_down_region_lists();
254 void rebuild_region_lists();
256 // The sequence of all heap regions in the heap.
257 HeapRegionSeq _hrs;
259 // Alloc region used to satisfy mutator allocation requests.
260 MutatorAllocRegion _mutator_alloc_region;
262 // Alloc region used to satisfy allocation requests by the GC for
263 // survivor objects.
264 SurvivorGCAllocRegion _survivor_gc_alloc_region;
266 // Alloc region used to satisfy allocation requests by the GC for
267 // old objects.
268 OldGCAllocRegion _old_gc_alloc_region;
270 // The last old region we allocated to during the last GC.
271 // Typically, it is not full so we should re-use it during the next GC.
272 HeapRegion* _retained_old_gc_alloc_region;
274 // It resets the mutator alloc region before new allocations can take place.
275 void init_mutator_alloc_region();
277 // It releases the mutator alloc region.
278 void release_mutator_alloc_region();
280 // It initializes the GC alloc regions at the start of a GC.
281 void init_gc_alloc_regions();
283 // It releases the GC alloc regions at the end of a GC.
284 void release_gc_alloc_regions();
286 // It does any cleanup that needs to be done on the GC alloc regions
287 // before a Full GC.
288 void abandon_gc_alloc_regions();
290 // Helper for monitoring and management support.
291 G1MonitoringSupport* _g1mm;
293 // Determines PLAB size for a particular allocation purpose.
294 static size_t desired_plab_sz(GCAllocPurpose purpose);
296 // Outside of GC pauses, the number of bytes used in all regions other
297 // than the current allocation region.
298 size_t _summary_bytes_used;
300 // This is used for a quick test on whether a reference points into
301 // the collection set or not. Basically, we have an array, with one
302 // byte per region, and that byte denotes whether the corresponding
303 // region is in the collection set or not. The entry corresponding
304 // the bottom of the heap, i.e., region 0, is pointed to by
305 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
306 // biased so that it actually points to address 0 of the address
307 // space, to make the test as fast as possible (we can simply shift
308 // the address to address into it, instead of having to subtract the
309 // bottom of the heap from the address before shifting it; basically
310 // it works in the same way the card table works).
311 bool* _in_cset_fast_test;
313 // The allocated array used for the fast test on whether a reference
314 // points into the collection set or not. This field is also used to
315 // free the array.
316 bool* _in_cset_fast_test_base;
318 // The length of the _in_cset_fast_test_base array.
319 size_t _in_cset_fast_test_length;
321 volatile unsigned _gc_time_stamp;
323 size_t* _surviving_young_words;
325 G1HRPrinter _hr_printer;
327 void setup_surviving_young_words();
328 void update_surviving_young_words(size_t* surv_young_words);
329 void cleanup_surviving_young_words();
331 // It decides whether an explicit GC should start a concurrent cycle
332 // instead of doing a STW GC. Currently, a concurrent cycle is
333 // explicitly started if:
334 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
335 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
336 bool should_do_concurrent_full_gc(GCCause::Cause cause);
338 // Keeps track of how many "full collections" (i.e., Full GCs or
339 // concurrent cycles) we have completed. The number of them we have
340 // started is maintained in _total_full_collections in CollectedHeap.
341 volatile unsigned int _full_collections_completed;
343 // This is a non-product method that is helpful for testing. It is
344 // called at the end of a GC and artificially expands the heap by
345 // allocating a number of dead regions. This way we can induce very
346 // frequent marking cycles and stress the cleanup / concurrent
347 // cleanup code more (as all the regions that will be allocated by
348 // this method will be found dead by the marking cycle).
349 void allocate_dummy_regions() PRODUCT_RETURN;
351 // These are macros so that, if the assert fires, we get the correct
352 // line number, file, etc.
354 #define heap_locking_asserts_err_msg(_extra_message_) \
355 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
356 (_extra_message_), \
357 BOOL_TO_STR(Heap_lock->owned_by_self()), \
358 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
359 BOOL_TO_STR(Thread::current()->is_VM_thread()))
361 #define assert_heap_locked() \
362 do { \
363 assert(Heap_lock->owned_by_self(), \
364 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
365 } while (0)
367 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
368 do { \
369 assert(Heap_lock->owned_by_self() || \
370 (SafepointSynchronize::is_at_safepoint() && \
371 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
372 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
373 "should be at a safepoint")); \
374 } while (0)
376 #define assert_heap_locked_and_not_at_safepoint() \
377 do { \
378 assert(Heap_lock->owned_by_self() && \
379 !SafepointSynchronize::is_at_safepoint(), \
380 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
381 "should not be at a safepoint")); \
382 } while (0)
384 #define assert_heap_not_locked() \
385 do { \
386 assert(!Heap_lock->owned_by_self(), \
387 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
388 } while (0)
390 #define assert_heap_not_locked_and_not_at_safepoint() \
391 do { \
392 assert(!Heap_lock->owned_by_self() && \
393 !SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
395 "should not be at a safepoint")); \
396 } while (0)
398 #define assert_at_safepoint(_should_be_vm_thread_) \
399 do { \
400 assert(SafepointSynchronize::is_at_safepoint() && \
401 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
402 heap_locking_asserts_err_msg("should be at a safepoint")); \
403 } while (0)
405 #define assert_not_at_safepoint() \
406 do { \
407 assert(!SafepointSynchronize::is_at_safepoint(), \
408 heap_locking_asserts_err_msg("should not be at a safepoint")); \
409 } while (0)
411 protected:
413 // The young region list.
414 YoungList* _young_list;
416 // The current policy object for the collector.
417 G1CollectorPolicy* _g1_policy;
419 // This is the second level of trying to allocate a new region. If
420 // new_region() didn't find a region on the free_list, this call will
421 // check whether there's anything available on the
422 // secondary_free_list and/or wait for more regions to appear on
423 // that list, if _free_regions_coming is set.
424 HeapRegion* new_region_try_secondary_free_list();
426 // Try to allocate a single non-humongous HeapRegion sufficient for
427 // an allocation of the given word_size. If do_expand is true,
428 // attempt to expand the heap if necessary to satisfy the allocation
429 // request.
430 HeapRegion* new_region(size_t word_size, bool do_expand);
432 // Attempt to satisfy a humongous allocation request of the given
433 // size by finding a contiguous set of free regions of num_regions
434 // length and remove them from the master free list. Return the
435 // index of the first region or G1_NULL_HRS_INDEX if the search
436 // was unsuccessful.
437 size_t humongous_obj_allocate_find_first(size_t num_regions,
438 size_t word_size);
440 // Initialize a contiguous set of free regions of length num_regions
441 // and starting at index first so that they appear as a single
442 // humongous region.
443 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
444 size_t num_regions,
445 size_t word_size);
447 // Attempt to allocate a humongous object of the given size. Return
448 // NULL if unsuccessful.
449 HeapWord* humongous_obj_allocate(size_t word_size);
451 // The following two methods, allocate_new_tlab() and
452 // mem_allocate(), are the two main entry points from the runtime
453 // into the G1's allocation routines. They have the following
454 // assumptions:
455 //
456 // * They should both be called outside safepoints.
457 //
458 // * They should both be called without holding the Heap_lock.
459 //
460 // * All allocation requests for new TLABs should go to
461 // allocate_new_tlab().
462 //
463 // * All non-TLAB allocation requests should go to mem_allocate().
464 //
465 // * If either call cannot satisfy the allocation request using the
466 // current allocating region, they will try to get a new one. If
467 // this fails, they will attempt to do an evacuation pause and
468 // retry the allocation.
469 //
470 // * If all allocation attempts fail, even after trying to schedule
471 // an evacuation pause, allocate_new_tlab() will return NULL,
472 // whereas mem_allocate() will attempt a heap expansion and/or
473 // schedule a Full GC.
474 //
475 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
476 // should never be called with word_size being humongous. All
477 // humongous allocation requests should go to mem_allocate() which
478 // will satisfy them with a special path.
480 virtual HeapWord* allocate_new_tlab(size_t word_size);
482 virtual HeapWord* mem_allocate(size_t word_size,
483 bool* gc_overhead_limit_was_exceeded);
485 // The following three methods take a gc_count_before_ret
486 // parameter which is used to return the GC count if the method
487 // returns NULL. Given that we are required to read the GC count
488 // while holding the Heap_lock, and these paths will take the
489 // Heap_lock at some point, it's easier to get them to read the GC
490 // count while holding the Heap_lock before they return NULL instead
491 // of the caller (namely: mem_allocate()) having to also take the
492 // Heap_lock just to read the GC count.
494 // First-level mutator allocation attempt: try to allocate out of
495 // the mutator alloc region without taking the Heap_lock. This
496 // should only be used for non-humongous allocations.
497 inline HeapWord* attempt_allocation(size_t word_size,
498 unsigned int* gc_count_before_ret);
500 // Second-level mutator allocation attempt: take the Heap_lock and
501 // retry the allocation attempt, potentially scheduling a GC
502 // pause. This should only be used for non-humongous allocations.
503 HeapWord* attempt_allocation_slow(size_t word_size,
504 unsigned int* gc_count_before_ret);
506 // Takes the Heap_lock and attempts a humongous allocation. It can
507 // potentially schedule a GC pause.
508 HeapWord* attempt_allocation_humongous(size_t word_size,
509 unsigned int* gc_count_before_ret);
511 // Allocation attempt that should be called during safepoints (e.g.,
512 // at the end of a successful GC). expect_null_mutator_alloc_region
513 // specifies whether the mutator alloc region is expected to be NULL
514 // or not.
515 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
516 bool expect_null_mutator_alloc_region);
518 // It dirties the cards that cover the block so that so that the post
519 // write barrier never queues anything when updating objects on this
520 // block. It is assumed (and in fact we assert) that the block
521 // belongs to a young region.
522 inline void dirty_young_block(HeapWord* start, size_t word_size);
524 // Allocate blocks during garbage collection. Will ensure an
525 // allocation region, either by picking one or expanding the
526 // heap, and then allocate a block of the given size. The block
527 // may not be a humongous - it must fit into a single heap region.
528 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
530 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
531 HeapRegion* alloc_region,
532 bool par,
533 size_t word_size);
535 // Ensure that no further allocations can happen in "r", bearing in mind
536 // that parallel threads might be attempting allocations.
537 void par_allocate_remaining_space(HeapRegion* r);
539 // Allocation attempt during GC for a survivor object / PLAB.
540 inline HeapWord* survivor_attempt_allocation(size_t word_size);
542 // Allocation attempt during GC for an old object / PLAB.
543 inline HeapWord* old_attempt_allocation(size_t word_size);
545 // These methods are the "callbacks" from the G1AllocRegion class.
547 // For mutator alloc regions.
548 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
549 void retire_mutator_alloc_region(HeapRegion* alloc_region,
550 size_t allocated_bytes);
552 // For GC alloc regions.
553 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
554 GCAllocPurpose ap);
555 void retire_gc_alloc_region(HeapRegion* alloc_region,
556 size_t allocated_bytes, GCAllocPurpose ap);
558 // - if explicit_gc is true, the GC is for a System.gc() or a heap
559 // inspection request and should collect the entire heap
560 // - if clear_all_soft_refs is true, all soft references should be
561 // cleared during the GC
562 // - if explicit_gc is false, word_size describes the allocation that
563 // the GC should attempt (at least) to satisfy
564 // - it returns false if it is unable to do the collection due to the
565 // GC locker being active, true otherwise
566 bool do_collection(bool explicit_gc,
567 bool clear_all_soft_refs,
568 size_t word_size);
570 // Callback from VM_G1CollectFull operation.
571 // Perform a full collection.
572 void do_full_collection(bool clear_all_soft_refs);
574 // Resize the heap if necessary after a full collection. If this is
575 // after a collect-for allocation, "word_size" is the allocation size,
576 // and will be considered part of the used portion of the heap.
577 void resize_if_necessary_after_full_collection(size_t word_size);
579 // Callback from VM_G1CollectForAllocation operation.
580 // This function does everything necessary/possible to satisfy a
581 // failed allocation request (including collection, expansion, etc.)
582 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
584 // Attempting to expand the heap sufficiently
585 // to support an allocation of the given "word_size". If
586 // successful, perform the allocation and return the address of the
587 // allocated block, or else "NULL".
588 HeapWord* expand_and_allocate(size_t word_size);
590 // Process any reference objects discovered during
591 // an incremental evacuation pause.
592 void process_discovered_references();
594 // Enqueue any remaining discovered references
595 // after processing.
596 void enqueue_discovered_references();
598 public:
600 G1MonitoringSupport* g1mm() { return _g1mm; }
602 // Expand the garbage-first heap by at least the given size (in bytes!).
603 // Returns true if the heap was expanded by the requested amount;
604 // false otherwise.
605 // (Rounds up to a HeapRegion boundary.)
606 bool expand(size_t expand_bytes);
608 // Do anything common to GC's.
609 virtual void gc_prologue(bool full);
610 virtual void gc_epilogue(bool full);
612 // We register a region with the fast "in collection set" test. We
613 // simply set to true the array slot corresponding to this region.
614 void register_region_with_in_cset_fast_test(HeapRegion* r) {
615 assert(_in_cset_fast_test_base != NULL, "sanity");
616 assert(r->in_collection_set(), "invariant");
617 size_t index = r->hrs_index();
618 assert(index < _in_cset_fast_test_length, "invariant");
619 assert(!_in_cset_fast_test_base[index], "invariant");
620 _in_cset_fast_test_base[index] = true;
621 }
623 // This is a fast test on whether a reference points into the
624 // collection set or not. It does not assume that the reference
625 // points into the heap; if it doesn't, it will return false.
626 bool in_cset_fast_test(oop obj) {
627 assert(_in_cset_fast_test != NULL, "sanity");
628 if (_g1_committed.contains((HeapWord*) obj)) {
629 // no need to subtract the bottom of the heap from obj,
630 // _in_cset_fast_test is biased
631 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
632 bool ret = _in_cset_fast_test[index];
633 // let's make sure the result is consistent with what the slower
634 // test returns
635 assert( ret || !obj_in_cs(obj), "sanity");
636 assert(!ret || obj_in_cs(obj), "sanity");
637 return ret;
638 } else {
639 return false;
640 }
641 }
643 void clear_cset_fast_test() {
644 assert(_in_cset_fast_test_base != NULL, "sanity");
645 memset(_in_cset_fast_test_base, false,
646 _in_cset_fast_test_length * sizeof(bool));
647 }
649 // This is called at the end of either a concurrent cycle or a Full
650 // GC to update the number of full collections completed. Those two
651 // can happen in a nested fashion, i.e., we start a concurrent
652 // cycle, a Full GC happens half-way through it which ends first,
653 // and then the cycle notices that a Full GC happened and ends
654 // too. The concurrent parameter is a boolean to help us do a bit
655 // tighter consistency checking in the method. If concurrent is
656 // false, the caller is the inner caller in the nesting (i.e., the
657 // Full GC). If concurrent is true, the caller is the outer caller
658 // in this nesting (i.e., the concurrent cycle). Further nesting is
659 // not currently supported. The end of the this call also notifies
660 // the FullGCCount_lock in case a Java thread is waiting for a full
661 // GC to happen (e.g., it called System.gc() with
662 // +ExplicitGCInvokesConcurrent).
663 void increment_full_collections_completed(bool concurrent);
665 unsigned int full_collections_completed() {
666 return _full_collections_completed;
667 }
669 G1HRPrinter* hr_printer() { return &_hr_printer; }
671 protected:
673 // Shrink the garbage-first heap by at most the given size (in bytes!).
674 // (Rounds down to a HeapRegion boundary.)
675 virtual void shrink(size_t expand_bytes);
676 void shrink_helper(size_t expand_bytes);
678 #if TASKQUEUE_STATS
679 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
680 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
681 void reset_taskqueue_stats();
682 #endif // TASKQUEUE_STATS
684 // Schedule the VM operation that will do an evacuation pause to
685 // satisfy an allocation request of word_size. *succeeded will
686 // return whether the VM operation was successful (it did do an
687 // evacuation pause) or not (another thread beat us to it or the GC
688 // locker was active). Given that we should not be holding the
689 // Heap_lock when we enter this method, we will pass the
690 // gc_count_before (i.e., total_collections()) as a parameter since
691 // it has to be read while holding the Heap_lock. Currently, both
692 // methods that call do_collection_pause() release the Heap_lock
693 // before the call, so it's easy to read gc_count_before just before.
694 HeapWord* do_collection_pause(size_t word_size,
695 unsigned int gc_count_before,
696 bool* succeeded);
698 // The guts of the incremental collection pause, executed by the vm
699 // thread. It returns false if it is unable to do the collection due
700 // to the GC locker being active, true otherwise
701 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
703 // Actually do the work of evacuating the collection set.
704 void evacuate_collection_set();
706 // The g1 remembered set of the heap.
707 G1RemSet* _g1_rem_set;
708 // And it's mod ref barrier set, used to track updates for the above.
709 ModRefBarrierSet* _mr_bs;
711 // A set of cards that cover the objects for which the Rsets should be updated
712 // concurrently after the collection.
713 DirtyCardQueueSet _dirty_card_queue_set;
715 // The Heap Region Rem Set Iterator.
716 HeapRegionRemSetIterator** _rem_set_iterator;
718 // The closure used to refine a single card.
719 RefineCardTableEntryClosure* _refine_cte_cl;
721 // A function to check the consistency of dirty card logs.
722 void check_ct_logs_at_safepoint();
724 // A DirtyCardQueueSet that is used to hold cards that contain
725 // references into the current collection set. This is used to
726 // update the remembered sets of the regions in the collection
727 // set in the event of an evacuation failure.
728 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
730 // After a collection pause, make the regions in the CS into free
731 // regions.
732 void free_collection_set(HeapRegion* cs_head);
734 // Abandon the current collection set without recording policy
735 // statistics or updating free lists.
736 void abandon_collection_set(HeapRegion* cs_head);
738 // Applies "scan_non_heap_roots" to roots outside the heap,
739 // "scan_rs" to roots inside the heap (having done "set_region" to
740 // indicate the region in which the root resides), and does "scan_perm"
741 // (setting the generation to the perm generation.) If "scan_rs" is
742 // NULL, then this step is skipped. The "worker_i"
743 // param is for use with parallel roots processing, and should be
744 // the "i" of the calling parallel worker thread's work(i) function.
745 // In the sequential case this param will be ignored.
746 void g1_process_strong_roots(bool collecting_perm_gen,
747 SharedHeap::ScanningOption so,
748 OopClosure* scan_non_heap_roots,
749 OopsInHeapRegionClosure* scan_rs,
750 OopsInGenClosure* scan_perm,
751 int worker_i);
753 // Apply "blk" to all the weak roots of the system. These include
754 // JNI weak roots, the code cache, system dictionary, symbol table,
755 // string table, and referents of reachable weak refs.
756 void g1_process_weak_roots(OopClosure* root_closure,
757 OopClosure* non_root_closure);
759 // Frees a non-humongous region by initializing its contents and
760 // adding it to the free list that's passed as a parameter (this is
761 // usually a local list which will be appended to the master free
762 // list later). The used bytes of freed regions are accumulated in
763 // pre_used. If par is true, the region's RSet will not be freed
764 // up. The assumption is that this will be done later.
765 void free_region(HeapRegion* hr,
766 size_t* pre_used,
767 FreeRegionList* free_list,
768 bool par);
770 // Frees a humongous region by collapsing it into individual regions
771 // and calling free_region() for each of them. The freed regions
772 // will be added to the free list that's passed as a parameter (this
773 // is usually a local list which will be appended to the master free
774 // list later). The used bytes of freed regions are accumulated in
775 // pre_used. If par is true, the region's RSet will not be freed
776 // up. The assumption is that this will be done later.
777 void free_humongous_region(HeapRegion* hr,
778 size_t* pre_used,
779 FreeRegionList* free_list,
780 HumongousRegionSet* humongous_proxy_set,
781 bool par);
783 // Notifies all the necessary spaces that the committed space has
784 // been updated (either expanded or shrunk). It should be called
785 // after _g1_storage is updated.
786 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
788 // The concurrent marker (and the thread it runs in.)
789 ConcurrentMark* _cm;
790 ConcurrentMarkThread* _cmThread;
791 bool _mark_in_progress;
793 // The concurrent refiner.
794 ConcurrentG1Refine* _cg1r;
796 // The parallel task queues
797 RefToScanQueueSet *_task_queues;
799 // True iff a evacuation has failed in the current collection.
800 bool _evacuation_failed;
802 // Set the attribute indicating whether evacuation has failed in the
803 // current collection.
804 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
806 // Failed evacuations cause some logical from-space objects to have
807 // forwarding pointers to themselves. Reset them.
808 void remove_self_forwarding_pointers();
810 // When one is non-null, so is the other. Together, they each pair is
811 // an object with a preserved mark, and its mark value.
812 GrowableArray<oop>* _objs_with_preserved_marks;
813 GrowableArray<markOop>* _preserved_marks_of_objs;
815 // Preserve the mark of "obj", if necessary, in preparation for its mark
816 // word being overwritten with a self-forwarding-pointer.
817 void preserve_mark_if_necessary(oop obj, markOop m);
819 // The stack of evac-failure objects left to be scanned.
820 GrowableArray<oop>* _evac_failure_scan_stack;
821 // The closure to apply to evac-failure objects.
823 OopsInHeapRegionClosure* _evac_failure_closure;
824 // Set the field above.
825 void
826 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
827 _evac_failure_closure = evac_failure_closure;
828 }
830 // Push "obj" on the scan stack.
831 void push_on_evac_failure_scan_stack(oop obj);
832 // Process scan stack entries until the stack is empty.
833 void drain_evac_failure_scan_stack();
834 // True iff an invocation of "drain_scan_stack" is in progress; to
835 // prevent unnecessary recursion.
836 bool _drain_in_progress;
838 // Do any necessary initialization for evacuation-failure handling.
839 // "cl" is the closure that will be used to process evac-failure
840 // objects.
841 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
842 // Do any necessary cleanup for evacuation-failure handling data
843 // structures.
844 void finalize_for_evac_failure();
846 // An attempt to evacuate "obj" has failed; take necessary steps.
847 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj,
848 bool should_mark_root);
849 void handle_evacuation_failure_common(oop obj, markOop m);
851 // ("Weak") Reference processing support.
852 //
853 // G1 has 2 instances of the referece processor class. One
854 // (_ref_processor_cm) handles reference object discovery
855 // and subsequent processing during concurrent marking cycles.
856 //
857 // The other (_ref_processor_stw) handles reference object
858 // discovery and processing during full GCs and incremental
859 // evacuation pauses.
860 //
861 // During an incremental pause, reference discovery will be
862 // temporarily disabled for _ref_processor_cm and will be
863 // enabled for _ref_processor_stw. At the end of the evacuation
864 // pause references discovered by _ref_processor_stw will be
865 // processed and discovery will be disabled. The previous
866 // setting for reference object discovery for _ref_processor_cm
867 // will be re-instated.
868 //
869 // At the start of marking:
870 // * Discovery by the CM ref processor is verified to be inactive
871 // and it's discovered lists are empty.
872 // * Discovery by the CM ref processor is then enabled.
873 //
874 // At the end of marking:
875 // * Any references on the CM ref processor's discovered
876 // lists are processed (possibly MT).
877 //
878 // At the start of full GC we:
879 // * Disable discovery by the CM ref processor and
880 // empty CM ref processor's discovered lists
881 // (without processing any entries).
882 // * Verify that the STW ref processor is inactive and it's
883 // discovered lists are empty.
884 // * Temporarily set STW ref processor discovery as single threaded.
885 // * Temporarily clear the STW ref processor's _is_alive_non_header
886 // field.
887 // * Finally enable discovery by the STW ref processor.
888 //
889 // The STW ref processor is used to record any discovered
890 // references during the full GC.
891 //
892 // At the end of a full GC we:
893 // * Enqueue any reference objects discovered by the STW ref processor
894 // that have non-live referents. This has the side-effect of
895 // making the STW ref processor inactive by disabling discovery.
896 // * Verify that the CM ref processor is still inactive
897 // and no references have been placed on it's discovered
898 // lists (also checked as a precondition during initial marking).
900 // The (stw) reference processor...
901 ReferenceProcessor* _ref_processor_stw;
903 // During reference object discovery, the _is_alive_non_header
904 // closure (if non-null) is applied to the referent object to
905 // determine whether the referent is live. If so then the
906 // reference object does not need to be 'discovered' and can
907 // be treated as a regular oop. This has the benefit of reducing
908 // the number of 'discovered' reference objects that need to
909 // be processed.
910 //
911 // Instance of the is_alive closure for embedding into the
912 // STW reference processor as the _is_alive_non_header field.
913 // Supplying a value for the _is_alive_non_header field is
914 // optional but doing so prevents unnecessary additions to
915 // the discovered lists during reference discovery.
916 G1STWIsAliveClosure _is_alive_closure_stw;
918 // The (concurrent marking) reference processor...
919 ReferenceProcessor* _ref_processor_cm;
921 // Instance of the concurrent mark is_alive closure for embedding
922 // into the Concurrent Marking reference processor as the
923 // _is_alive_non_header field. Supplying a value for the
924 // _is_alive_non_header field is optional but doing so prevents
925 // unnecessary additions to the discovered lists during reference
926 // discovery.
927 G1CMIsAliveClosure _is_alive_closure_cm;
929 enum G1H_process_strong_roots_tasks {
930 G1H_PS_mark_stack_oops_do,
931 G1H_PS_refProcessor_oops_do,
932 // Leave this one last.
933 G1H_PS_NumElements
934 };
936 SubTasksDone* _process_strong_tasks;
938 volatile bool _free_regions_coming;
940 public:
942 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
944 void set_refine_cte_cl_concurrency(bool concurrent);
946 RefToScanQueue *task_queue(int i) const;
948 // A set of cards where updates happened during the GC
949 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
951 // A DirtyCardQueueSet that is used to hold cards that contain
952 // references into the current collection set. This is used to
953 // update the remembered sets of the regions in the collection
954 // set in the event of an evacuation failure.
955 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
956 { return _into_cset_dirty_card_queue_set; }
958 // Create a G1CollectedHeap with the specified policy.
959 // Must call the initialize method afterwards.
960 // May not return if something goes wrong.
961 G1CollectedHeap(G1CollectorPolicy* policy);
963 // Initialize the G1CollectedHeap to have the initial and
964 // maximum sizes, permanent generation, and remembered and barrier sets
965 // specified by the policy object.
966 jint initialize();
968 // Initialize weak reference processing.
969 virtual void ref_processing_init();
971 void set_par_threads(int t) {
972 SharedHeap::set_par_threads(t);
973 _process_strong_tasks->set_n_threads(t);
974 }
976 virtual CollectedHeap::Name kind() const {
977 return CollectedHeap::G1CollectedHeap;
978 }
980 // The current policy object for the collector.
981 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
983 // Adaptive size policy. No such thing for g1.
984 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
986 // The rem set and barrier set.
987 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
988 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
990 // The rem set iterator.
991 HeapRegionRemSetIterator* rem_set_iterator(int i) {
992 return _rem_set_iterator[i];
993 }
995 HeapRegionRemSetIterator* rem_set_iterator() {
996 return _rem_set_iterator[0];
997 }
999 unsigned get_gc_time_stamp() {
1000 return _gc_time_stamp;
1001 }
1003 void reset_gc_time_stamp() {
1004 _gc_time_stamp = 0;
1005 OrderAccess::fence();
1006 }
1008 void increment_gc_time_stamp() {
1009 ++_gc_time_stamp;
1010 OrderAccess::fence();
1011 }
1013 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1014 DirtyCardQueue* into_cset_dcq,
1015 bool concurrent, int worker_i);
1017 // The shared block offset table array.
1018 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1020 // Reference Processing accessors
1022 // The STW reference processor....
1023 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1025 // The Concurent Marking reference processor...
1026 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1028 virtual size_t capacity() const;
1029 virtual size_t used() const;
1030 // This should be called when we're not holding the heap lock. The
1031 // result might be a bit inaccurate.
1032 size_t used_unlocked() const;
1033 size_t recalculate_used() const;
1035 // These virtual functions do the actual allocation.
1036 // Some heaps may offer a contiguous region for shared non-blocking
1037 // allocation, via inlined code (by exporting the address of the top and
1038 // end fields defining the extent of the contiguous allocation region.)
1039 // But G1CollectedHeap doesn't yet support this.
1041 // Return an estimate of the maximum allocation that could be performed
1042 // without triggering any collection or expansion activity. In a
1043 // generational collector, for example, this is probably the largest
1044 // allocation that could be supported (without expansion) in the youngest
1045 // generation. It is "unsafe" because no locks are taken; the result
1046 // should be treated as an approximation, not a guarantee, for use in
1047 // heuristic resizing decisions.
1048 virtual size_t unsafe_max_alloc();
1050 virtual bool is_maximal_no_gc() const {
1051 return _g1_storage.uncommitted_size() == 0;
1052 }
1054 // The total number of regions in the heap.
1055 size_t n_regions() { return _hrs.length(); }
1057 // The max number of regions in the heap.
1058 size_t max_regions() { return _hrs.max_length(); }
1060 // The number of regions that are completely free.
1061 size_t free_regions() { return _free_list.length(); }
1063 // The number of regions that are not completely free.
1064 size_t used_regions() { return n_regions() - free_regions(); }
1066 // The number of regions available for "regular" expansion.
1067 size_t expansion_regions() { return _expansion_regions; }
1069 // Factory method for HeapRegion instances. It will return NULL if
1070 // the allocation fails.
1071 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1073 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1074 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1075 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1076 void verify_dirty_young_regions() PRODUCT_RETURN;
1078 // verify_region_sets() performs verification over the region
1079 // lists. It will be compiled in the product code to be used when
1080 // necessary (i.e., during heap verification).
1081 void verify_region_sets();
1083 // verify_region_sets_optional() is planted in the code for
1084 // list verification in non-product builds (and it can be enabled in
1085 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1086 #if HEAP_REGION_SET_FORCE_VERIFY
1087 void verify_region_sets_optional() {
1088 verify_region_sets();
1089 }
1090 #else // HEAP_REGION_SET_FORCE_VERIFY
1091 void verify_region_sets_optional() { }
1092 #endif // HEAP_REGION_SET_FORCE_VERIFY
1094 #ifdef ASSERT
1095 bool is_on_master_free_list(HeapRegion* hr) {
1096 return hr->containing_set() == &_free_list;
1097 }
1099 bool is_in_humongous_set(HeapRegion* hr) {
1100 return hr->containing_set() == &_humongous_set;
1101 }
1102 #endif // ASSERT
1104 // Wrapper for the region list operations that can be called from
1105 // methods outside this class.
1107 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1108 _secondary_free_list.add_as_tail(list);
1109 }
1111 void append_secondary_free_list() {
1112 _free_list.add_as_head(&_secondary_free_list);
1113 }
1115 void append_secondary_free_list_if_not_empty_with_lock() {
1116 // If the secondary free list looks empty there's no reason to
1117 // take the lock and then try to append it.
1118 if (!_secondary_free_list.is_empty()) {
1119 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1120 append_secondary_free_list();
1121 }
1122 }
1124 void set_free_regions_coming();
1125 void reset_free_regions_coming();
1126 bool free_regions_coming() { return _free_regions_coming; }
1127 void wait_while_free_regions_coming();
1129 // Perform a collection of the heap; intended for use in implementing
1130 // "System.gc". This probably implies as full a collection as the
1131 // "CollectedHeap" supports.
1132 virtual void collect(GCCause::Cause cause);
1134 // The same as above but assume that the caller holds the Heap_lock.
1135 void collect_locked(GCCause::Cause cause);
1137 // This interface assumes that it's being called by the
1138 // vm thread. It collects the heap assuming that the
1139 // heap lock is already held and that we are executing in
1140 // the context of the vm thread.
1141 virtual void collect_as_vm_thread(GCCause::Cause cause);
1143 // True iff a evacuation has failed in the most-recent collection.
1144 bool evacuation_failed() { return _evacuation_failed; }
1146 // It will free a region if it has allocated objects in it that are
1147 // all dead. It calls either free_region() or
1148 // free_humongous_region() depending on the type of the region that
1149 // is passed to it.
1150 void free_region_if_empty(HeapRegion* hr,
1151 size_t* pre_used,
1152 FreeRegionList* free_list,
1153 HumongousRegionSet* humongous_proxy_set,
1154 HRRSCleanupTask* hrrs_cleanup_task,
1155 bool par);
1157 // It appends the free list to the master free list and updates the
1158 // master humongous list according to the contents of the proxy
1159 // list. It also adjusts the total used bytes according to pre_used
1160 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1161 void update_sets_after_freeing_regions(size_t pre_used,
1162 FreeRegionList* free_list,
1163 HumongousRegionSet* humongous_proxy_set,
1164 bool par);
1166 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1167 virtual bool is_in(const void* p) const;
1169 // Return "TRUE" iff the given object address is within the collection
1170 // set.
1171 inline bool obj_in_cs(oop obj);
1173 // Return "TRUE" iff the given object address is in the reserved
1174 // region of g1 (excluding the permanent generation).
1175 bool is_in_g1_reserved(const void* p) const {
1176 return _g1_reserved.contains(p);
1177 }
1179 // Returns a MemRegion that corresponds to the space that has been
1180 // reserved for the heap
1181 MemRegion g1_reserved() {
1182 return _g1_reserved;
1183 }
1185 // Returns a MemRegion that corresponds to the space that has been
1186 // committed in the heap
1187 MemRegion g1_committed() {
1188 return _g1_committed;
1189 }
1191 virtual bool is_in_closed_subset(const void* p) const;
1193 // This resets the card table to all zeros. It is used after
1194 // a collection pause which used the card table to claim cards.
1195 void cleanUpCardTable();
1197 // Iteration functions.
1199 // Iterate over all the ref-containing fields of all objects, calling
1200 // "cl.do_oop" on each.
1201 virtual void oop_iterate(OopClosure* cl) {
1202 oop_iterate(cl, true);
1203 }
1204 void oop_iterate(OopClosure* cl, bool do_perm);
1206 // Same as above, restricted to a memory region.
1207 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1208 oop_iterate(mr, cl, true);
1209 }
1210 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1212 // Iterate over all objects, calling "cl.do_object" on each.
1213 virtual void object_iterate(ObjectClosure* cl) {
1214 object_iterate(cl, true);
1215 }
1216 virtual void safe_object_iterate(ObjectClosure* cl) {
1217 object_iterate(cl, true);
1218 }
1219 void object_iterate(ObjectClosure* cl, bool do_perm);
1221 // Iterate over all objects allocated since the last collection, calling
1222 // "cl.do_object" on each. The heap must have been initialized properly
1223 // to support this function, or else this call will fail.
1224 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1226 // Iterate over all spaces in use in the heap, in ascending address order.
1227 virtual void space_iterate(SpaceClosure* cl);
1229 // Iterate over heap regions, in address order, terminating the
1230 // iteration early if the "doHeapRegion" method returns "true".
1231 void heap_region_iterate(HeapRegionClosure* blk) const;
1233 // Iterate over heap regions starting with r (or the first region if "r"
1234 // is NULL), in address order, terminating early if the "doHeapRegion"
1235 // method returns "true".
1236 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1238 // Return the region with the given index. It assumes the index is valid.
1239 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1241 // Divide the heap region sequence into "chunks" of some size (the number
1242 // of regions divided by the number of parallel threads times some
1243 // overpartition factor, currently 4). Assumes that this will be called
1244 // in parallel by ParallelGCThreads worker threads with discinct worker
1245 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1246 // calls will use the same "claim_value", and that that claim value is
1247 // different from the claim_value of any heap region before the start of
1248 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1249 // attempting to claim the first region in each chunk, and, if
1250 // successful, applying the closure to each region in the chunk (and
1251 // setting the claim value of the second and subsequent regions of the
1252 // chunk.) For now requires that "doHeapRegion" always returns "false",
1253 // i.e., that a closure never attempt to abort a traversal.
1254 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1255 int worker,
1256 jint claim_value);
1258 // It resets all the region claim values to the default.
1259 void reset_heap_region_claim_values();
1261 #ifdef ASSERT
1262 bool check_heap_region_claim_values(jint claim_value);
1263 #endif // ASSERT
1265 // Iterate over the regions (if any) in the current collection set.
1266 void collection_set_iterate(HeapRegionClosure* blk);
1268 // As above but starting from region r
1269 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1271 // Returns the first (lowest address) compactible space in the heap.
1272 virtual CompactibleSpace* first_compactible_space();
1274 // A CollectedHeap will contain some number of spaces. This finds the
1275 // space containing a given address, or else returns NULL.
1276 virtual Space* space_containing(const void* addr) const;
1278 // A G1CollectedHeap will contain some number of heap regions. This
1279 // finds the region containing a given address, or else returns NULL.
1280 template <class T>
1281 inline HeapRegion* heap_region_containing(const T addr) const;
1283 // Like the above, but requires "addr" to be in the heap (to avoid a
1284 // null-check), and unlike the above, may return an continuing humongous
1285 // region.
1286 template <class T>
1287 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1289 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1290 // each address in the (reserved) heap is a member of exactly
1291 // one block. The defining characteristic of a block is that it is
1292 // possible to find its size, and thus to progress forward to the next
1293 // block. (Blocks may be of different sizes.) Thus, blocks may
1294 // represent Java objects, or they might be free blocks in a
1295 // free-list-based heap (or subheap), as long as the two kinds are
1296 // distinguishable and the size of each is determinable.
1298 // Returns the address of the start of the "block" that contains the
1299 // address "addr". We say "blocks" instead of "object" since some heaps
1300 // may not pack objects densely; a chunk may either be an object or a
1301 // non-object.
1302 virtual HeapWord* block_start(const void* addr) const;
1304 // Requires "addr" to be the start of a chunk, and returns its size.
1305 // "addr + size" is required to be the start of a new chunk, or the end
1306 // of the active area of the heap.
1307 virtual size_t block_size(const HeapWord* addr) const;
1309 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1310 // the block is an object.
1311 virtual bool block_is_obj(const HeapWord* addr) const;
1313 // Does this heap support heap inspection? (+PrintClassHistogram)
1314 virtual bool supports_heap_inspection() const { return true; }
1316 // Section on thread-local allocation buffers (TLABs)
1317 // See CollectedHeap for semantics.
1319 virtual bool supports_tlab_allocation() const;
1320 virtual size_t tlab_capacity(Thread* thr) const;
1321 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1323 // Can a compiler initialize a new object without store barriers?
1324 // This permission only extends from the creation of a new object
1325 // via a TLAB up to the first subsequent safepoint. If such permission
1326 // is granted for this heap type, the compiler promises to call
1327 // defer_store_barrier() below on any slow path allocation of
1328 // a new object for which such initializing store barriers will
1329 // have been elided. G1, like CMS, allows this, but should be
1330 // ready to provide a compensating write barrier as necessary
1331 // if that storage came out of a non-young region. The efficiency
1332 // of this implementation depends crucially on being able to
1333 // answer very efficiently in constant time whether a piece of
1334 // storage in the heap comes from a young region or not.
1335 // See ReduceInitialCardMarks.
1336 virtual bool can_elide_tlab_store_barriers() const {
1337 // 6920090: Temporarily disabled, because of lingering
1338 // instabilities related to RICM with G1. In the
1339 // interim, the option ReduceInitialCardMarksForG1
1340 // below is left solely as a debugging device at least
1341 // until 6920109 fixes the instabilities.
1342 return ReduceInitialCardMarksForG1;
1343 }
1345 virtual bool card_mark_must_follow_store() const {
1346 return true;
1347 }
1349 bool is_in_young(const oop obj) {
1350 HeapRegion* hr = heap_region_containing(obj);
1351 return hr != NULL && hr->is_young();
1352 }
1354 #ifdef ASSERT
1355 virtual bool is_in_partial_collection(const void* p);
1356 #endif
1358 virtual bool is_scavengable(const void* addr);
1360 // We don't need barriers for initializing stores to objects
1361 // in the young gen: for the SATB pre-barrier, there is no
1362 // pre-value that needs to be remembered; for the remembered-set
1363 // update logging post-barrier, we don't maintain remembered set
1364 // information for young gen objects.
1365 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1366 // Re 6920090, 6920109 above.
1367 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1368 return is_in_young(new_obj);
1369 }
1371 // Can a compiler elide a store barrier when it writes
1372 // a permanent oop into the heap? Applies when the compiler
1373 // is storing x to the heap, where x->is_perm() is true.
1374 virtual bool can_elide_permanent_oop_store_barriers() const {
1375 // At least until perm gen collection is also G1-ified, at
1376 // which point this should return false.
1377 return true;
1378 }
1380 // Returns "true" iff the given word_size is "very large".
1381 static bool isHumongous(size_t word_size) {
1382 // Note this has to be strictly greater-than as the TLABs
1383 // are capped at the humongous thresold and we want to
1384 // ensure that we don't try to allocate a TLAB as
1385 // humongous and that we don't allocate a humongous
1386 // object in a TLAB.
1387 return word_size > _humongous_object_threshold_in_words;
1388 }
1390 // Update mod union table with the set of dirty cards.
1391 void updateModUnion();
1393 // Set the mod union bits corresponding to the given memRegion. Note
1394 // that this is always a safe operation, since it doesn't clear any
1395 // bits.
1396 void markModUnionRange(MemRegion mr);
1398 // Records the fact that a marking phase is no longer in progress.
1399 void set_marking_complete() {
1400 _mark_in_progress = false;
1401 }
1402 void set_marking_started() {
1403 _mark_in_progress = true;
1404 }
1405 bool mark_in_progress() {
1406 return _mark_in_progress;
1407 }
1409 // Print the maximum heap capacity.
1410 virtual size_t max_capacity() const;
1412 virtual jlong millis_since_last_gc();
1414 // Perform any cleanup actions necessary before allowing a verification.
1415 virtual void prepare_for_verify();
1417 // Perform verification.
1419 // vo == UsePrevMarking -> use "prev" marking information,
1420 // vo == UseNextMarking -> use "next" marking information
1421 // vo == UseMarkWord -> use the mark word in the object header
1422 //
1423 // NOTE: Only the "prev" marking information is guaranteed to be
1424 // consistent most of the time, so most calls to this should use
1425 // vo == UsePrevMarking.
1426 // Currently, there is only one case where this is called with
1427 // vo == UseNextMarking, which is to verify the "next" marking
1428 // information at the end of remark.
1429 // Currently there is only one place where this is called with
1430 // vo == UseMarkWord, which is to verify the marking during a
1431 // full GC.
1432 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1434 // Override; it uses the "prev" marking information
1435 virtual void verify(bool allow_dirty, bool silent);
1436 // Default behavior by calling print(tty);
1437 virtual void print() const;
1438 // This calls print_on(st, PrintHeapAtGCExtended).
1439 virtual void print_on(outputStream* st) const;
1440 // If extended is true, it will print out information for all
1441 // regions in the heap by calling print_on_extended(st).
1442 virtual void print_on(outputStream* st, bool extended) const;
1443 virtual void print_on_extended(outputStream* st) const;
1445 virtual void print_gc_threads_on(outputStream* st) const;
1446 virtual void gc_threads_do(ThreadClosure* tc) const;
1448 // Override
1449 void print_tracing_info() const;
1451 // The following two methods are helpful for debugging RSet issues.
1452 void print_cset_rsets() PRODUCT_RETURN;
1453 void print_all_rsets() PRODUCT_RETURN;
1455 // Convenience function to be used in situations where the heap type can be
1456 // asserted to be this type.
1457 static G1CollectedHeap* heap();
1459 void empty_young_list();
1461 void set_region_short_lived_locked(HeapRegion* hr);
1462 // add appropriate methods for any other surv rate groups
1464 YoungList* young_list() { return _young_list; }
1466 // debugging
1467 bool check_young_list_well_formed() {
1468 return _young_list->check_list_well_formed();
1469 }
1471 bool check_young_list_empty(bool check_heap,
1472 bool check_sample = true);
1474 // *** Stuff related to concurrent marking. It's not clear to me that so
1475 // many of these need to be public.
1477 // The functions below are helper functions that a subclass of
1478 // "CollectedHeap" can use in the implementation of its virtual
1479 // functions.
1480 // This performs a concurrent marking of the live objects in a
1481 // bitmap off to the side.
1482 void doConcurrentMark();
1484 bool isMarkedPrev(oop obj) const;
1485 bool isMarkedNext(oop obj) const;
1487 // vo == UsePrevMarking -> use "prev" marking information,
1488 // vo == UseNextMarking -> use "next" marking information,
1489 // vo == UseMarkWord -> use mark word from object header
1490 bool is_obj_dead_cond(const oop obj,
1491 const HeapRegion* hr,
1492 const VerifyOption vo) const {
1494 switch (vo) {
1495 case VerifyOption_G1UsePrevMarking:
1496 return is_obj_dead(obj, hr);
1497 case VerifyOption_G1UseNextMarking:
1498 return is_obj_ill(obj, hr);
1499 default:
1500 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1501 return !obj->is_gc_marked();
1502 }
1503 }
1505 // Determine if an object is dead, given the object and also
1506 // the region to which the object belongs. An object is dead
1507 // iff a) it was not allocated since the last mark and b) it
1508 // is not marked.
1510 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1511 return
1512 !hr->obj_allocated_since_prev_marking(obj) &&
1513 !isMarkedPrev(obj);
1514 }
1516 // This is used when copying an object to survivor space.
1517 // If the object is marked live, then we mark the copy live.
1518 // If the object is allocated since the start of this mark
1519 // cycle, then we mark the copy live.
1520 // If the object has been around since the previous mark
1521 // phase, and hasn't been marked yet during this phase,
1522 // then we don't mark it, we just wait for the
1523 // current marking cycle to get to it.
1525 // This function returns true when an object has been
1526 // around since the previous marking and hasn't yet
1527 // been marked during this marking.
1529 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1530 return
1531 !hr->obj_allocated_since_next_marking(obj) &&
1532 !isMarkedNext(obj);
1533 }
1535 // Determine if an object is dead, given only the object itself.
1536 // This will find the region to which the object belongs and
1537 // then call the region version of the same function.
1539 // Added if it is in permanent gen it isn't dead.
1540 // Added if it is NULL it isn't dead.
1542 // vo == UsePrevMarking -> use "prev" marking information,
1543 // vo == UseNextMarking -> use "next" marking information,
1544 // vo == UseMarkWord -> use mark word from object header
1545 bool is_obj_dead_cond(const oop obj,
1546 const VerifyOption vo) const {
1548 switch (vo) {
1549 case VerifyOption_G1UsePrevMarking:
1550 return is_obj_dead(obj);
1551 case VerifyOption_G1UseNextMarking:
1552 return is_obj_ill(obj);
1553 default:
1554 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1555 return !obj->is_gc_marked();
1556 }
1557 }
1559 bool is_obj_dead(const oop obj) const {
1560 const HeapRegion* hr = heap_region_containing(obj);
1561 if (hr == NULL) {
1562 if (Universe::heap()->is_in_permanent(obj))
1563 return false;
1564 else if (obj == NULL) return false;
1565 else return true;
1566 }
1567 else return is_obj_dead(obj, hr);
1568 }
1570 bool is_obj_ill(const oop obj) const {
1571 const HeapRegion* hr = heap_region_containing(obj);
1572 if (hr == NULL) {
1573 if (Universe::heap()->is_in_permanent(obj))
1574 return false;
1575 else if (obj == NULL) return false;
1576 else return true;
1577 }
1578 else return is_obj_ill(obj, hr);
1579 }
1581 // The following is just to alert the verification code
1582 // that a full collection has occurred and that the
1583 // remembered sets are no longer up to date.
1584 bool _full_collection;
1585 void set_full_collection() { _full_collection = true;}
1586 void clear_full_collection() {_full_collection = false;}
1587 bool full_collection() {return _full_collection;}
1589 ConcurrentMark* concurrent_mark() const { return _cm; }
1590 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1592 // The dirty cards region list is used to record a subset of regions
1593 // whose cards need clearing. The list if populated during the
1594 // remembered set scanning and drained during the card table
1595 // cleanup. Although the methods are reentrant, population/draining
1596 // phases must not overlap. For synchronization purposes the last
1597 // element on the list points to itself.
1598 HeapRegion* _dirty_cards_region_list;
1599 void push_dirty_cards_region(HeapRegion* hr);
1600 HeapRegion* pop_dirty_cards_region();
1602 public:
1603 void stop_conc_gc_threads();
1605 // <NEW PREDICTION>
1607 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1608 void check_if_region_is_too_expensive(double predicted_time_ms);
1609 size_t pending_card_num();
1610 size_t max_pending_card_num();
1611 size_t cards_scanned();
1613 // </NEW PREDICTION>
1615 protected:
1616 size_t _max_heap_capacity;
1617 };
1619 #define use_local_bitmaps 1
1620 #define verify_local_bitmaps 0
1621 #define oop_buffer_length 256
1623 #ifndef PRODUCT
1624 class GCLabBitMap;
1625 class GCLabBitMapClosure: public BitMapClosure {
1626 private:
1627 ConcurrentMark* _cm;
1628 GCLabBitMap* _bitmap;
1630 public:
1631 GCLabBitMapClosure(ConcurrentMark* cm,
1632 GCLabBitMap* bitmap) {
1633 _cm = cm;
1634 _bitmap = bitmap;
1635 }
1637 virtual bool do_bit(size_t offset);
1638 };
1639 #endif // !PRODUCT
1641 class GCLabBitMap: public BitMap {
1642 private:
1643 ConcurrentMark* _cm;
1645 int _shifter;
1646 size_t _bitmap_word_covers_words;
1648 // beginning of the heap
1649 HeapWord* _heap_start;
1651 // this is the actual start of the GCLab
1652 HeapWord* _real_start_word;
1654 // this is the actual end of the GCLab
1655 HeapWord* _real_end_word;
1657 // this is the first word, possibly located before the actual start
1658 // of the GCLab, that corresponds to the first bit of the bitmap
1659 HeapWord* _start_word;
1661 // size of a GCLab in words
1662 size_t _gclab_word_size;
1664 static int shifter() {
1665 return MinObjAlignment - 1;
1666 }
1668 // how many heap words does a single bitmap word corresponds to?
1669 static size_t bitmap_word_covers_words() {
1670 return BitsPerWord << shifter();
1671 }
1673 size_t gclab_word_size() const {
1674 return _gclab_word_size;
1675 }
1677 // Calculates actual GCLab size in words
1678 size_t gclab_real_word_size() const {
1679 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1680 / BitsPerWord;
1681 }
1683 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1684 size_t bits_in_bitmap = gclab_word_size >> shifter();
1685 // We are going to ensure that the beginning of a word in this
1686 // bitmap also corresponds to the beginning of a word in the
1687 // global marking bitmap. To handle the case where a GCLab
1688 // starts from the middle of the bitmap, we need to add enough
1689 // space (i.e. up to a bitmap word) to ensure that we have
1690 // enough bits in the bitmap.
1691 return bits_in_bitmap + BitsPerWord - 1;
1692 }
1693 public:
1694 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1695 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1696 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1697 _shifter(shifter()),
1698 _bitmap_word_covers_words(bitmap_word_covers_words()),
1699 _heap_start(heap_start),
1700 _gclab_word_size(gclab_word_size),
1701 _real_start_word(NULL),
1702 _real_end_word(NULL),
1703 _start_word(NULL)
1704 {
1705 guarantee( size_in_words() >= bitmap_size_in_words(),
1706 "just making sure");
1707 }
1709 inline unsigned heapWordToOffset(HeapWord* addr) {
1710 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1711 assert(offset < size(), "offset should be within bounds");
1712 return offset;
1713 }
1715 inline HeapWord* offsetToHeapWord(size_t offset) {
1716 HeapWord* addr = _start_word + (offset << _shifter);
1717 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1718 return addr;
1719 }
1721 bool fields_well_formed() {
1722 bool ret1 = (_real_start_word == NULL) &&
1723 (_real_end_word == NULL) &&
1724 (_start_word == NULL);
1725 if (ret1)
1726 return true;
1728 bool ret2 = _real_start_word >= _start_word &&
1729 _start_word < _real_end_word &&
1730 (_real_start_word + _gclab_word_size) == _real_end_word &&
1731 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1732 > _real_end_word;
1733 return ret2;
1734 }
1736 inline bool mark(HeapWord* addr) {
1737 guarantee(use_local_bitmaps, "invariant");
1738 assert(fields_well_formed(), "invariant");
1740 if (addr >= _real_start_word && addr < _real_end_word) {
1741 assert(!isMarked(addr), "should not have already been marked");
1743 // first mark it on the bitmap
1744 at_put(heapWordToOffset(addr), true);
1746 return true;
1747 } else {
1748 return false;
1749 }
1750 }
1752 inline bool isMarked(HeapWord* addr) {
1753 guarantee(use_local_bitmaps, "invariant");
1754 assert(fields_well_formed(), "invariant");
1756 return at(heapWordToOffset(addr));
1757 }
1759 void set_buffer(HeapWord* start) {
1760 guarantee(use_local_bitmaps, "invariant");
1761 clear();
1763 assert(start != NULL, "invariant");
1764 _real_start_word = start;
1765 _real_end_word = start + _gclab_word_size;
1767 size_t diff =
1768 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1769 _start_word = start - diff;
1771 assert(fields_well_formed(), "invariant");
1772 }
1774 #ifndef PRODUCT
1775 void verify() {
1776 // verify that the marks have been propagated
1777 GCLabBitMapClosure cl(_cm, this);
1778 iterate(&cl);
1779 }
1780 #endif // PRODUCT
1782 void retire() {
1783 guarantee(use_local_bitmaps, "invariant");
1784 assert(fields_well_formed(), "invariant");
1786 if (_start_word != NULL) {
1787 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1789 // this means that the bitmap was set up for the GCLab
1790 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1792 mark_bitmap->mostly_disjoint_range_union(this,
1793 0, // always start from the start of the bitmap
1794 _start_word,
1795 gclab_real_word_size());
1796 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1798 #ifndef PRODUCT
1799 if (use_local_bitmaps && verify_local_bitmaps)
1800 verify();
1801 #endif // PRODUCT
1802 } else {
1803 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1804 }
1805 }
1807 size_t bitmap_size_in_words() const {
1808 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1809 }
1811 };
1813 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1814 private:
1815 bool _retired;
1816 bool _should_mark_objects;
1817 GCLabBitMap _bitmap;
1819 public:
1820 G1ParGCAllocBuffer(size_t gclab_word_size);
1822 inline bool mark(HeapWord* addr) {
1823 guarantee(use_local_bitmaps, "invariant");
1824 assert(_should_mark_objects, "invariant");
1825 return _bitmap.mark(addr);
1826 }
1828 inline void set_buf(HeapWord* buf) {
1829 if (use_local_bitmaps && _should_mark_objects) {
1830 _bitmap.set_buffer(buf);
1831 }
1832 ParGCAllocBuffer::set_buf(buf);
1833 _retired = false;
1834 }
1836 inline void retire(bool end_of_gc, bool retain) {
1837 if (_retired)
1838 return;
1839 if (use_local_bitmaps && _should_mark_objects) {
1840 _bitmap.retire();
1841 }
1842 ParGCAllocBuffer::retire(end_of_gc, retain);
1843 _retired = true;
1844 }
1845 };
1847 class G1ParScanThreadState : public StackObj {
1848 protected:
1849 G1CollectedHeap* _g1h;
1850 RefToScanQueue* _refs;
1851 DirtyCardQueue _dcq;
1852 CardTableModRefBS* _ct_bs;
1853 G1RemSet* _g1_rem;
1855 G1ParGCAllocBuffer _surviving_alloc_buffer;
1856 G1ParGCAllocBuffer _tenured_alloc_buffer;
1857 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1858 ageTable _age_table;
1860 size_t _alloc_buffer_waste;
1861 size_t _undo_waste;
1863 OopsInHeapRegionClosure* _evac_failure_cl;
1864 G1ParScanHeapEvacClosure* _evac_cl;
1865 G1ParScanPartialArrayClosure* _partial_scan_cl;
1867 int _hash_seed;
1868 int _queue_num;
1870 size_t _term_attempts;
1872 double _start;
1873 double _start_strong_roots;
1874 double _strong_roots_time;
1875 double _start_term;
1876 double _term_time;
1878 // Map from young-age-index (0 == not young, 1 is youngest) to
1879 // surviving words. base is what we get back from the malloc call
1880 size_t* _surviving_young_words_base;
1881 // this points into the array, as we use the first few entries for padding
1882 size_t* _surviving_young_words;
1884 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1886 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1888 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1890 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1891 CardTableModRefBS* ctbs() { return _ct_bs; }
1893 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1894 if (!from->is_survivor()) {
1895 _g1_rem->par_write_ref(from, p, tid);
1896 }
1897 }
1899 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1900 // If the new value of the field points to the same region or
1901 // is the to-space, we don't need to include it in the Rset updates.
1902 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1903 size_t card_index = ctbs()->index_for(p);
1904 // If the card hasn't been added to the buffer, do it.
1905 if (ctbs()->mark_card_deferred(card_index)) {
1906 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1907 }
1908 }
1909 }
1911 public:
1912 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1914 ~G1ParScanThreadState() {
1915 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1916 }
1918 RefToScanQueue* refs() { return _refs; }
1919 ageTable* age_table() { return &_age_table; }
1921 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1922 return _alloc_buffers[purpose];
1923 }
1925 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1926 size_t undo_waste() const { return _undo_waste; }
1928 #ifdef ASSERT
1929 bool verify_ref(narrowOop* ref) const;
1930 bool verify_ref(oop* ref) const;
1931 bool verify_task(StarTask ref) const;
1932 #endif // ASSERT
1934 template <class T> void push_on_queue(T* ref) {
1935 assert(verify_ref(ref), "sanity");
1936 refs()->push(ref);
1937 }
1939 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1940 if (G1DeferredRSUpdate) {
1941 deferred_rs_update(from, p, tid);
1942 } else {
1943 immediate_rs_update(from, p, tid);
1944 }
1945 }
1947 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1949 HeapWord* obj = NULL;
1950 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1951 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1952 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1953 assert(gclab_word_size == alloc_buf->word_sz(),
1954 "dynamic resizing is not supported");
1955 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1956 alloc_buf->retire(false, false);
1958 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1959 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1960 // Otherwise.
1961 alloc_buf->set_buf(buf);
1963 obj = alloc_buf->allocate(word_sz);
1964 assert(obj != NULL, "buffer was definitely big enough...");
1965 } else {
1966 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1967 }
1968 return obj;
1969 }
1971 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1972 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1973 if (obj != NULL) return obj;
1974 return allocate_slow(purpose, word_sz);
1975 }
1977 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1978 if (alloc_buffer(purpose)->contains(obj)) {
1979 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1980 "should contain whole object");
1981 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1982 } else {
1983 CollectedHeap::fill_with_object(obj, word_sz);
1984 add_to_undo_waste(word_sz);
1985 }
1986 }
1988 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1989 _evac_failure_cl = evac_failure_cl;
1990 }
1991 OopsInHeapRegionClosure* evac_failure_closure() {
1992 return _evac_failure_cl;
1993 }
1995 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1996 _evac_cl = evac_cl;
1997 }
1999 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2000 _partial_scan_cl = partial_scan_cl;
2001 }
2003 int* hash_seed() { return &_hash_seed; }
2004 int queue_num() { return _queue_num; }
2006 size_t term_attempts() const { return _term_attempts; }
2007 void note_term_attempt() { _term_attempts++; }
2009 void start_strong_roots() {
2010 _start_strong_roots = os::elapsedTime();
2011 }
2012 void end_strong_roots() {
2013 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2014 }
2015 double strong_roots_time() const { return _strong_roots_time; }
2017 void start_term_time() {
2018 note_term_attempt();
2019 _start_term = os::elapsedTime();
2020 }
2021 void end_term_time() {
2022 _term_time += (os::elapsedTime() - _start_term);
2023 }
2024 double term_time() const { return _term_time; }
2026 double elapsed_time() const {
2027 return os::elapsedTime() - _start;
2028 }
2030 static void
2031 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2032 void
2033 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2035 size_t* surviving_young_words() {
2036 // We add on to hide entry 0 which accumulates surviving words for
2037 // age -1 regions (i.e. non-young ones)
2038 return _surviving_young_words;
2039 }
2041 void retire_alloc_buffers() {
2042 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2043 size_t waste = _alloc_buffers[ap]->words_remaining();
2044 add_to_alloc_buffer_waste(waste);
2045 _alloc_buffers[ap]->retire(true, false);
2046 }
2047 }
2049 template <class T> void deal_with_reference(T* ref_to_scan) {
2050 if (has_partial_array_mask(ref_to_scan)) {
2051 _partial_scan_cl->do_oop_nv(ref_to_scan);
2052 } else {
2053 // Note: we can use "raw" versions of "region_containing" because
2054 // "obj_to_scan" is definitely in the heap, and is not in a
2055 // humongous region.
2056 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2057 _evac_cl->set_region(r);
2058 _evac_cl->do_oop_nv(ref_to_scan);
2059 }
2060 }
2062 void deal_with_reference(StarTask ref) {
2063 assert(verify_task(ref), "sanity");
2064 if (ref.is_narrow()) {
2065 deal_with_reference((narrowOop*)ref);
2066 } else {
2067 deal_with_reference((oop*)ref);
2068 }
2069 }
2071 public:
2072 void trim_queue();
2073 };
2075 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP