Mon, 24 Mar 2014 15:30:56 +0100
8035330: Remove G1ParScanPartialArrayClosure and G1ParScanHeapEvacClosure
Summary: Mentioned closures are actually wrapped methods. This adds confusion to readers, and in this case also increases code size as G1ParScanHeapEvacClosure is part of the oop_oop_iterate() methods. Move them into G1ParScanThreadState as methods.
Reviewed-by: stefank
1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
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23 */
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/evacuationInfo.hpp"
30 #include "gc_implementation/g1/g1AllocRegion.hpp"
31 #include "gc_implementation/g1/g1HRPrinter.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/g1RemSet.hpp"
34 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
35 #include "gc_implementation/g1/g1YCTypes.hpp"
36 #include "gc_implementation/g1/heapRegionSeq.hpp"
37 #include "gc_implementation/g1/heapRegionSet.hpp"
38 #include "gc_implementation/shared/hSpaceCounters.hpp"
39 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
40 #include "memory/barrierSet.hpp"
41 #include "memory/memRegion.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "utilities/stack.hpp"
45 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
46 // It uses the "Garbage First" heap organization and algorithm, which
47 // may combine concurrent marking with parallel, incremental compaction of
48 // heap subsets that will yield large amounts of garbage.
50 // Forward declarations
51 class HeapRegion;
52 class HRRSCleanupTask;
53 class GenerationSpec;
54 class OopsInHeapRegionClosure;
55 class G1KlassScanClosure;
56 class G1ScanHeapEvacClosure;
57 class ObjectClosure;
58 class SpaceClosure;
59 class CompactibleSpaceClosure;
60 class Space;
61 class G1CollectorPolicy;
62 class GenRemSet;
63 class G1RemSet;
64 class HeapRegionRemSetIterator;
65 class ConcurrentMark;
66 class ConcurrentMarkThread;
67 class ConcurrentG1Refine;
68 class ConcurrentGCTimer;
69 class GenerationCounters;
70 class STWGCTimer;
71 class G1NewTracer;
72 class G1OldTracer;
73 class EvacuationFailedInfo;
74 class nmethod;
75 class Ticks;
77 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
78 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
80 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
81 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
83 enum GCAllocPurpose {
84 GCAllocForTenured,
85 GCAllocForSurvived,
86 GCAllocPurposeCount
87 };
89 class YoungList : public CHeapObj<mtGC> {
90 private:
91 G1CollectedHeap* _g1h;
93 HeapRegion* _head;
95 HeapRegion* _survivor_head;
96 HeapRegion* _survivor_tail;
98 HeapRegion* _curr;
100 uint _length;
101 uint _survivor_length;
103 size_t _last_sampled_rs_lengths;
104 size_t _sampled_rs_lengths;
106 void empty_list(HeapRegion* list);
108 public:
109 YoungList(G1CollectedHeap* g1h);
111 void push_region(HeapRegion* hr);
112 void add_survivor_region(HeapRegion* hr);
114 void empty_list();
115 bool is_empty() { return _length == 0; }
116 uint length() { return _length; }
117 uint survivor_length() { return _survivor_length; }
119 // Currently we do not keep track of the used byte sum for the
120 // young list and the survivors and it'd be quite a lot of work to
121 // do so. When we'll eventually replace the young list with
122 // instances of HeapRegionLinkedList we'll get that for free. So,
123 // we'll report the more accurate information then.
124 size_t eden_used_bytes() {
125 assert(length() >= survivor_length(), "invariant");
126 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
127 }
128 size_t survivor_used_bytes() {
129 return (size_t) survivor_length() * HeapRegion::GrainBytes;
130 }
132 void rs_length_sampling_init();
133 bool rs_length_sampling_more();
134 void rs_length_sampling_next();
136 void reset_sampled_info() {
137 _last_sampled_rs_lengths = 0;
138 }
139 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
141 // for development purposes
142 void reset_auxilary_lists();
143 void clear() { _head = NULL; _length = 0; }
145 void clear_survivors() {
146 _survivor_head = NULL;
147 _survivor_tail = NULL;
148 _survivor_length = 0;
149 }
151 HeapRegion* first_region() { return _head; }
152 HeapRegion* first_survivor_region() { return _survivor_head; }
153 HeapRegion* last_survivor_region() { return _survivor_tail; }
155 // debugging
156 bool check_list_well_formed();
157 bool check_list_empty(bool check_sample = true);
158 void print();
159 };
161 class MutatorAllocRegion : public G1AllocRegion {
162 protected:
163 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
164 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
165 public:
166 MutatorAllocRegion()
167 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
168 };
170 class SurvivorGCAllocRegion : public G1AllocRegion {
171 protected:
172 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
173 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
174 public:
175 SurvivorGCAllocRegion()
176 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
177 };
179 class OldGCAllocRegion : public G1AllocRegion {
180 protected:
181 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
182 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
183 public:
184 OldGCAllocRegion()
185 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
186 };
188 // The G1 STW is alive closure.
189 // An instance is embedded into the G1CH and used as the
190 // (optional) _is_alive_non_header closure in the STW
191 // reference processor. It is also extensively used during
192 // reference processing during STW evacuation pauses.
193 class G1STWIsAliveClosure: public BoolObjectClosure {
194 G1CollectedHeap* _g1;
195 public:
196 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
197 bool do_object_b(oop p);
198 };
200 class RefineCardTableEntryClosure;
202 class G1CollectedHeap : public SharedHeap {
203 friend class VM_G1CollectForAllocation;
204 friend class VM_G1CollectFull;
205 friend class VM_G1IncCollectionPause;
206 friend class VMStructs;
207 friend class MutatorAllocRegion;
208 friend class SurvivorGCAllocRegion;
209 friend class OldGCAllocRegion;
211 // Closures used in implementation.
212 template <G1Barrier barrier, bool do_mark_object>
213 friend class G1ParCopyClosure;
214 friend class G1IsAliveClosure;
215 friend class G1EvacuateFollowersClosure;
216 friend class G1ParScanThreadState;
217 friend class G1ParScanClosureSuper;
218 friend class G1ParEvacuateFollowersClosure;
219 friend class G1ParTask;
220 friend class G1FreeGarbageRegionClosure;
221 friend class RefineCardTableEntryClosure;
222 friend class G1PrepareCompactClosure;
223 friend class RegionSorter;
224 friend class RegionResetter;
225 friend class CountRCClosure;
226 friend class EvacPopObjClosure;
227 friend class G1ParCleanupCTTask;
229 // Other related classes.
230 friend class G1MarkSweep;
232 private:
233 // The one and only G1CollectedHeap, so static functions can find it.
234 static G1CollectedHeap* _g1h;
236 static size_t _humongous_object_threshold_in_words;
238 // Storage for the G1 heap.
239 VirtualSpace _g1_storage;
240 MemRegion _g1_reserved;
242 // The part of _g1_storage that is currently committed.
243 MemRegion _g1_committed;
245 // The master free list. It will satisfy all new region allocations.
246 FreeRegionList _free_list;
248 // The secondary free list which contains regions that have been
249 // freed up during the cleanup process. This will be appended to the
250 // master free list when appropriate.
251 FreeRegionList _secondary_free_list;
253 // It keeps track of the old regions.
254 HeapRegionSet _old_set;
256 // It keeps track of the humongous regions.
257 HeapRegionSet _humongous_set;
259 // The number of regions we could create by expansion.
260 uint _expansion_regions;
262 // The block offset table for the G1 heap.
263 G1BlockOffsetSharedArray* _bot_shared;
265 // Tears down the region sets / lists so that they are empty and the
266 // regions on the heap do not belong to a region set / list. The
267 // only exception is the humongous set which we leave unaltered. If
268 // free_list_only is true, it will only tear down the master free
269 // list. It is called before a Full GC (free_list_only == false) or
270 // before heap shrinking (free_list_only == true).
271 void tear_down_region_sets(bool free_list_only);
273 // Rebuilds the region sets / lists so that they are repopulated to
274 // reflect the contents of the heap. The only exception is the
275 // humongous set which was not torn down in the first place. If
276 // free_list_only is true, it will only rebuild the master free
277 // list. It is called after a Full GC (free_list_only == false) or
278 // after heap shrinking (free_list_only == true).
279 void rebuild_region_sets(bool free_list_only);
281 // The sequence of all heap regions in the heap.
282 HeapRegionSeq _hrs;
284 // Alloc region used to satisfy mutator allocation requests.
285 MutatorAllocRegion _mutator_alloc_region;
287 // Alloc region used to satisfy allocation requests by the GC for
288 // survivor objects.
289 SurvivorGCAllocRegion _survivor_gc_alloc_region;
291 // PLAB sizing policy for survivors.
292 PLABStats _survivor_plab_stats;
294 // Alloc region used to satisfy allocation requests by the GC for
295 // old objects.
296 OldGCAllocRegion _old_gc_alloc_region;
298 // PLAB sizing policy for tenured objects.
299 PLABStats _old_plab_stats;
301 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
302 PLABStats* stats = NULL;
304 switch (purpose) {
305 case GCAllocForSurvived:
306 stats = &_survivor_plab_stats;
307 break;
308 case GCAllocForTenured:
309 stats = &_old_plab_stats;
310 break;
311 default:
312 assert(false, "unrecognized GCAllocPurpose");
313 }
315 return stats;
316 }
318 // The last old region we allocated to during the last GC.
319 // Typically, it is not full so we should re-use it during the next GC.
320 HeapRegion* _retained_old_gc_alloc_region;
322 // It specifies whether we should attempt to expand the heap after a
323 // region allocation failure. If heap expansion fails we set this to
324 // false so that we don't re-attempt the heap expansion (it's likely
325 // that subsequent expansion attempts will also fail if one fails).
326 // Currently, it is only consulted during GC and it's reset at the
327 // start of each GC.
328 bool _expand_heap_after_alloc_failure;
330 // It resets the mutator alloc region before new allocations can take place.
331 void init_mutator_alloc_region();
333 // It releases the mutator alloc region.
334 void release_mutator_alloc_region();
336 // It initializes the GC alloc regions at the start of a GC.
337 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
339 // It releases the GC alloc regions at the end of a GC.
340 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
342 // It does any cleanup that needs to be done on the GC alloc regions
343 // before a Full GC.
344 void abandon_gc_alloc_regions();
346 // Helper for monitoring and management support.
347 G1MonitoringSupport* _g1mm;
349 // Determines PLAB size for a particular allocation purpose.
350 size_t desired_plab_sz(GCAllocPurpose purpose);
352 // Outside of GC pauses, the number of bytes used in all regions other
353 // than the current allocation region.
354 size_t _summary_bytes_used;
356 // This is used for a quick test on whether a reference points into
357 // the collection set or not. Basically, we have an array, with one
358 // byte per region, and that byte denotes whether the corresponding
359 // region is in the collection set or not. The entry corresponding
360 // the bottom of the heap, i.e., region 0, is pointed to by
361 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
362 // biased so that it actually points to address 0 of the address
363 // space, to make the test as fast as possible (we can simply shift
364 // the address to address into it, instead of having to subtract the
365 // bottom of the heap from the address before shifting it; basically
366 // it works in the same way the card table works).
367 bool* _in_cset_fast_test;
369 // The allocated array used for the fast test on whether a reference
370 // points into the collection set or not. This field is also used to
371 // free the array.
372 bool* _in_cset_fast_test_base;
374 // The length of the _in_cset_fast_test_base array.
375 uint _in_cset_fast_test_length;
377 volatile unsigned _gc_time_stamp;
379 size_t* _surviving_young_words;
381 G1HRPrinter _hr_printer;
383 void setup_surviving_young_words();
384 void update_surviving_young_words(size_t* surv_young_words);
385 void cleanup_surviving_young_words();
387 // It decides whether an explicit GC should start a concurrent cycle
388 // instead of doing a STW GC. Currently, a concurrent cycle is
389 // explicitly started if:
390 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
391 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
392 // (c) cause == _g1_humongous_allocation
393 bool should_do_concurrent_full_gc(GCCause::Cause cause);
395 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
396 // concurrent cycles) we have started.
397 volatile unsigned int _old_marking_cycles_started;
399 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
400 // concurrent cycles) we have completed.
401 volatile unsigned int _old_marking_cycles_completed;
403 bool _concurrent_cycle_started;
405 // This is a non-product method that is helpful for testing. It is
406 // called at the end of a GC and artificially expands the heap by
407 // allocating a number of dead regions. This way we can induce very
408 // frequent marking cycles and stress the cleanup / concurrent
409 // cleanup code more (as all the regions that will be allocated by
410 // this method will be found dead by the marking cycle).
411 void allocate_dummy_regions() PRODUCT_RETURN;
413 // Clear RSets after a compaction. It also resets the GC time stamps.
414 void clear_rsets_post_compaction();
416 // If the HR printer is active, dump the state of the regions in the
417 // heap after a compaction.
418 void print_hrs_post_compaction();
420 double verify(bool guard, const char* msg);
421 void verify_before_gc();
422 void verify_after_gc();
424 void log_gc_header();
425 void log_gc_footer(double pause_time_sec);
427 // These are macros so that, if the assert fires, we get the correct
428 // line number, file, etc.
430 #define heap_locking_asserts_err_msg(_extra_message_) \
431 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
432 (_extra_message_), \
433 BOOL_TO_STR(Heap_lock->owned_by_self()), \
434 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
435 BOOL_TO_STR(Thread::current()->is_VM_thread()))
437 #define assert_heap_locked() \
438 do { \
439 assert(Heap_lock->owned_by_self(), \
440 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
441 } while (0)
443 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
444 do { \
445 assert(Heap_lock->owned_by_self() || \
446 (SafepointSynchronize::is_at_safepoint() && \
447 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
448 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
449 "should be at a safepoint")); \
450 } while (0)
452 #define assert_heap_locked_and_not_at_safepoint() \
453 do { \
454 assert(Heap_lock->owned_by_self() && \
455 !SafepointSynchronize::is_at_safepoint(), \
456 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
457 "should not be at a safepoint")); \
458 } while (0)
460 #define assert_heap_not_locked() \
461 do { \
462 assert(!Heap_lock->owned_by_self(), \
463 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
464 } while (0)
466 #define assert_heap_not_locked_and_not_at_safepoint() \
467 do { \
468 assert(!Heap_lock->owned_by_self() && \
469 !SafepointSynchronize::is_at_safepoint(), \
470 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
471 "should not be at a safepoint")); \
472 } while (0)
474 #define assert_at_safepoint(_should_be_vm_thread_) \
475 do { \
476 assert(SafepointSynchronize::is_at_safepoint() && \
477 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
478 heap_locking_asserts_err_msg("should be at a safepoint")); \
479 } while (0)
481 #define assert_not_at_safepoint() \
482 do { \
483 assert(!SafepointSynchronize::is_at_safepoint(), \
484 heap_locking_asserts_err_msg("should not be at a safepoint")); \
485 } while (0)
487 protected:
489 // The young region list.
490 YoungList* _young_list;
492 // The current policy object for the collector.
493 G1CollectorPolicy* _g1_policy;
495 // This is the second level of trying to allocate a new region. If
496 // new_region() didn't find a region on the free_list, this call will
497 // check whether there's anything available on the
498 // secondary_free_list and/or wait for more regions to appear on
499 // that list, if _free_regions_coming is set.
500 HeapRegion* new_region_try_secondary_free_list();
502 // Try to allocate a single non-humongous HeapRegion sufficient for
503 // an allocation of the given word_size. If do_expand is true,
504 // attempt to expand the heap if necessary to satisfy the allocation
505 // request.
506 HeapRegion* new_region(size_t word_size, bool do_expand);
508 // Attempt to satisfy a humongous allocation request of the given
509 // size by finding a contiguous set of free regions of num_regions
510 // length and remove them from the master free list. Return the
511 // index of the first region or G1_NULL_HRS_INDEX if the search
512 // was unsuccessful.
513 uint humongous_obj_allocate_find_first(uint num_regions,
514 size_t word_size);
516 // Initialize a contiguous set of free regions of length num_regions
517 // and starting at index first so that they appear as a single
518 // humongous region.
519 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
520 uint num_regions,
521 size_t word_size);
523 // Attempt to allocate a humongous object of the given size. Return
524 // NULL if unsuccessful.
525 HeapWord* humongous_obj_allocate(size_t word_size);
527 // The following two methods, allocate_new_tlab() and
528 // mem_allocate(), are the two main entry points from the runtime
529 // into the G1's allocation routines. They have the following
530 // assumptions:
531 //
532 // * They should both be called outside safepoints.
533 //
534 // * They should both be called without holding the Heap_lock.
535 //
536 // * All allocation requests for new TLABs should go to
537 // allocate_new_tlab().
538 //
539 // * All non-TLAB allocation requests should go to mem_allocate().
540 //
541 // * If either call cannot satisfy the allocation request using the
542 // current allocating region, they will try to get a new one. If
543 // this fails, they will attempt to do an evacuation pause and
544 // retry the allocation.
545 //
546 // * If all allocation attempts fail, even after trying to schedule
547 // an evacuation pause, allocate_new_tlab() will return NULL,
548 // whereas mem_allocate() will attempt a heap expansion and/or
549 // schedule a Full GC.
550 //
551 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
552 // should never be called with word_size being humongous. All
553 // humongous allocation requests should go to mem_allocate() which
554 // will satisfy them with a special path.
556 virtual HeapWord* allocate_new_tlab(size_t word_size);
558 virtual HeapWord* mem_allocate(size_t word_size,
559 bool* gc_overhead_limit_was_exceeded);
561 // The following three methods take a gc_count_before_ret
562 // parameter which is used to return the GC count if the method
563 // returns NULL. Given that we are required to read the GC count
564 // while holding the Heap_lock, and these paths will take the
565 // Heap_lock at some point, it's easier to get them to read the GC
566 // count while holding the Heap_lock before they return NULL instead
567 // of the caller (namely: mem_allocate()) having to also take the
568 // Heap_lock just to read the GC count.
570 // First-level mutator allocation attempt: try to allocate out of
571 // the mutator alloc region without taking the Heap_lock. This
572 // should only be used for non-humongous allocations.
573 inline HeapWord* attempt_allocation(size_t word_size,
574 unsigned int* gc_count_before_ret,
575 int* gclocker_retry_count_ret);
577 // Second-level mutator allocation attempt: take the Heap_lock and
578 // retry the allocation attempt, potentially scheduling a GC
579 // pause. This should only be used for non-humongous allocations.
580 HeapWord* attempt_allocation_slow(size_t word_size,
581 unsigned int* gc_count_before_ret,
582 int* gclocker_retry_count_ret);
584 // Takes the Heap_lock and attempts a humongous allocation. It can
585 // potentially schedule a GC pause.
586 HeapWord* attempt_allocation_humongous(size_t word_size,
587 unsigned int* gc_count_before_ret,
588 int* gclocker_retry_count_ret);
590 // Allocation attempt that should be called during safepoints (e.g.,
591 // at the end of a successful GC). expect_null_mutator_alloc_region
592 // specifies whether the mutator alloc region is expected to be NULL
593 // or not.
594 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
595 bool expect_null_mutator_alloc_region);
597 // It dirties the cards that cover the block so that so that the post
598 // write barrier never queues anything when updating objects on this
599 // block. It is assumed (and in fact we assert) that the block
600 // belongs to a young region.
601 inline void dirty_young_block(HeapWord* start, size_t word_size);
603 // Allocate blocks during garbage collection. Will ensure an
604 // allocation region, either by picking one or expanding the
605 // heap, and then allocate a block of the given size. The block
606 // may not be a humongous - it must fit into a single heap region.
607 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
609 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
610 HeapRegion* alloc_region,
611 bool par,
612 size_t word_size);
614 // Ensure that no further allocations can happen in "r", bearing in mind
615 // that parallel threads might be attempting allocations.
616 void par_allocate_remaining_space(HeapRegion* r);
618 // Allocation attempt during GC for a survivor object / PLAB.
619 inline HeapWord* survivor_attempt_allocation(size_t word_size);
621 // Allocation attempt during GC for an old object / PLAB.
622 inline HeapWord* old_attempt_allocation(size_t word_size);
624 // These methods are the "callbacks" from the G1AllocRegion class.
626 // For mutator alloc regions.
627 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
628 void retire_mutator_alloc_region(HeapRegion* alloc_region,
629 size_t allocated_bytes);
631 // For GC alloc regions.
632 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
633 GCAllocPurpose ap);
634 void retire_gc_alloc_region(HeapRegion* alloc_region,
635 size_t allocated_bytes, GCAllocPurpose ap);
637 // - if explicit_gc is true, the GC is for a System.gc() or a heap
638 // inspection request and should collect the entire heap
639 // - if clear_all_soft_refs is true, all soft references should be
640 // cleared during the GC
641 // - if explicit_gc is false, word_size describes the allocation that
642 // the GC should attempt (at least) to satisfy
643 // - it returns false if it is unable to do the collection due to the
644 // GC locker being active, true otherwise
645 bool do_collection(bool explicit_gc,
646 bool clear_all_soft_refs,
647 size_t word_size);
649 // Callback from VM_G1CollectFull operation.
650 // Perform a full collection.
651 virtual void do_full_collection(bool clear_all_soft_refs);
653 // Resize the heap if necessary after a full collection. If this is
654 // after a collect-for allocation, "word_size" is the allocation size,
655 // and will be considered part of the used portion of the heap.
656 void resize_if_necessary_after_full_collection(size_t word_size);
658 // Callback from VM_G1CollectForAllocation operation.
659 // This function does everything necessary/possible to satisfy a
660 // failed allocation request (including collection, expansion, etc.)
661 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
663 // Attempting to expand the heap sufficiently
664 // to support an allocation of the given "word_size". If
665 // successful, perform the allocation and return the address of the
666 // allocated block, or else "NULL".
667 HeapWord* expand_and_allocate(size_t word_size);
669 // Process any reference objects discovered during
670 // an incremental evacuation pause.
671 void process_discovered_references(uint no_of_gc_workers);
673 // Enqueue any remaining discovered references
674 // after processing.
675 void enqueue_discovered_references(uint no_of_gc_workers);
677 public:
679 G1MonitoringSupport* g1mm() {
680 assert(_g1mm != NULL, "should have been initialized");
681 return _g1mm;
682 }
684 // Expand the garbage-first heap by at least the given size (in bytes!).
685 // Returns true if the heap was expanded by the requested amount;
686 // false otherwise.
687 // (Rounds up to a HeapRegion boundary.)
688 bool expand(size_t expand_bytes);
690 // Do anything common to GC's.
691 virtual void gc_prologue(bool full);
692 virtual void gc_epilogue(bool full);
694 // We register a region with the fast "in collection set" test. We
695 // simply set to true the array slot corresponding to this region.
696 void register_region_with_in_cset_fast_test(HeapRegion* r) {
697 assert(_in_cset_fast_test_base != NULL, "sanity");
698 assert(r->in_collection_set(), "invariant");
699 uint index = r->hrs_index();
700 assert(index < _in_cset_fast_test_length, "invariant");
701 assert(!_in_cset_fast_test_base[index], "invariant");
702 _in_cset_fast_test_base[index] = true;
703 }
705 // This is a fast test on whether a reference points into the
706 // collection set or not. Assume that the reference
707 // points into the heap.
708 bool in_cset_fast_test(oop obj) {
709 assert(_in_cset_fast_test != NULL, "sanity");
710 assert(_g1_committed.contains((HeapWord*) obj), err_msg("Given reference outside of heap, is "PTR_FORMAT, (HeapWord*)obj));
711 // no need to subtract the bottom of the heap from obj,
712 // _in_cset_fast_test is biased
713 uintx index = cast_from_oop<uintx>(obj) >> HeapRegion::LogOfHRGrainBytes;
714 bool ret = _in_cset_fast_test[index];
715 // let's make sure the result is consistent with what the slower
716 // test returns
717 assert( ret || !obj_in_cs(obj), "sanity");
718 assert(!ret || obj_in_cs(obj), "sanity");
719 return ret;
720 }
722 void clear_cset_fast_test() {
723 assert(_in_cset_fast_test_base != NULL, "sanity");
724 memset(_in_cset_fast_test_base, false,
725 (size_t) _in_cset_fast_test_length * sizeof(bool));
726 }
728 // This is called at the start of either a concurrent cycle or a Full
729 // GC to update the number of old marking cycles started.
730 void increment_old_marking_cycles_started();
732 // This is called at the end of either a concurrent cycle or a Full
733 // GC to update the number of old marking cycles completed. Those two
734 // can happen in a nested fashion, i.e., we start a concurrent
735 // cycle, a Full GC happens half-way through it which ends first,
736 // and then the cycle notices that a Full GC happened and ends
737 // too. The concurrent parameter is a boolean to help us do a bit
738 // tighter consistency checking in the method. If concurrent is
739 // false, the caller is the inner caller in the nesting (i.e., the
740 // Full GC). If concurrent is true, the caller is the outer caller
741 // in this nesting (i.e., the concurrent cycle). Further nesting is
742 // not currently supported. The end of this call also notifies
743 // the FullGCCount_lock in case a Java thread is waiting for a full
744 // GC to happen (e.g., it called System.gc() with
745 // +ExplicitGCInvokesConcurrent).
746 void increment_old_marking_cycles_completed(bool concurrent);
748 unsigned int old_marking_cycles_completed() {
749 return _old_marking_cycles_completed;
750 }
752 void register_concurrent_cycle_start(const Ticks& start_time);
753 void register_concurrent_cycle_end();
754 void trace_heap_after_concurrent_cycle();
756 G1YCType yc_type();
758 G1HRPrinter* hr_printer() { return &_hr_printer; }
760 // Frees a non-humongous region by initializing its contents and
761 // adding it to the free list that's passed as a parameter (this is
762 // usually a local list which will be appended to the master free
763 // list later). The used bytes of freed regions are accumulated in
764 // pre_used. If par is true, the region's RSet will not be freed
765 // up. The assumption is that this will be done later.
766 // The locked parameter indicates if the caller has already taken
767 // care of proper synchronization. This may allow some optimizations.
768 void free_region(HeapRegion* hr,
769 FreeRegionList* free_list,
770 bool par,
771 bool locked = false);
773 // Frees a humongous region by collapsing it into individual regions
774 // and calling free_region() for each of them. The freed regions
775 // will be added to the free list that's passed as a parameter (this
776 // is usually a local list which will be appended to the master free
777 // list later). The used bytes of freed regions are accumulated in
778 // pre_used. If par is true, the region's RSet will not be freed
779 // up. The assumption is that this will be done later.
780 void free_humongous_region(HeapRegion* hr,
781 FreeRegionList* free_list,
782 bool par);
783 protected:
785 // Shrink the garbage-first heap by at most the given size (in bytes!).
786 // (Rounds down to a HeapRegion boundary.)
787 virtual void shrink(size_t expand_bytes);
788 void shrink_helper(size_t expand_bytes);
790 #if TASKQUEUE_STATS
791 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
792 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
793 void reset_taskqueue_stats();
794 #endif // TASKQUEUE_STATS
796 // Schedule the VM operation that will do an evacuation pause to
797 // satisfy an allocation request of word_size. *succeeded will
798 // return whether the VM operation was successful (it did do an
799 // evacuation pause) or not (another thread beat us to it or the GC
800 // locker was active). Given that we should not be holding the
801 // Heap_lock when we enter this method, we will pass the
802 // gc_count_before (i.e., total_collections()) as a parameter since
803 // it has to be read while holding the Heap_lock. Currently, both
804 // methods that call do_collection_pause() release the Heap_lock
805 // before the call, so it's easy to read gc_count_before just before.
806 HeapWord* do_collection_pause(size_t word_size,
807 unsigned int gc_count_before,
808 bool* succeeded,
809 GCCause::Cause gc_cause);
811 // The guts of the incremental collection pause, executed by the vm
812 // thread. It returns false if it is unable to do the collection due
813 // to the GC locker being active, true otherwise
814 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
816 // Actually do the work of evacuating the collection set.
817 void evacuate_collection_set(EvacuationInfo& evacuation_info);
819 // The g1 remembered set of the heap.
820 G1RemSet* _g1_rem_set;
822 // A set of cards that cover the objects for which the Rsets should be updated
823 // concurrently after the collection.
824 DirtyCardQueueSet _dirty_card_queue_set;
826 // The closure used to refine a single card.
827 RefineCardTableEntryClosure* _refine_cte_cl;
829 // A function to check the consistency of dirty card logs.
830 void check_ct_logs_at_safepoint();
832 // A DirtyCardQueueSet that is used to hold cards that contain
833 // references into the current collection set. This is used to
834 // update the remembered sets of the regions in the collection
835 // set in the event of an evacuation failure.
836 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
838 // After a collection pause, make the regions in the CS into free
839 // regions.
840 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
842 // Abandon the current collection set without recording policy
843 // statistics or updating free lists.
844 void abandon_collection_set(HeapRegion* cs_head);
846 // Applies "scan_non_heap_roots" to roots outside the heap,
847 // "scan_rs" to roots inside the heap (having done "set_region" to
848 // indicate the region in which the root resides),
849 // and does "scan_metadata" If "scan_rs" is
850 // NULL, then this step is skipped. The "worker_i"
851 // param is for use with parallel roots processing, and should be
852 // the "i" of the calling parallel worker thread's work(i) function.
853 // In the sequential case this param will be ignored.
854 void g1_process_strong_roots(bool is_scavenging,
855 ScanningOption so,
856 OopClosure* scan_non_heap_roots,
857 OopsInHeapRegionClosure* scan_rs,
858 G1KlassScanClosure* scan_klasses,
859 int worker_i);
861 // Apply "blk" to all the weak roots of the system. These include
862 // JNI weak roots, the code cache, system dictionary, symbol table,
863 // string table, and referents of reachable weak refs.
864 void g1_process_weak_roots(OopClosure* root_closure);
866 // Notifies all the necessary spaces that the committed space has
867 // been updated (either expanded or shrunk). It should be called
868 // after _g1_storage is updated.
869 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
871 // The concurrent marker (and the thread it runs in.)
872 ConcurrentMark* _cm;
873 ConcurrentMarkThread* _cmThread;
874 bool _mark_in_progress;
876 // The concurrent refiner.
877 ConcurrentG1Refine* _cg1r;
879 // The parallel task queues
880 RefToScanQueueSet *_task_queues;
882 // True iff a evacuation has failed in the current collection.
883 bool _evacuation_failed;
885 EvacuationFailedInfo* _evacuation_failed_info_array;
887 // Failed evacuations cause some logical from-space objects to have
888 // forwarding pointers to themselves. Reset them.
889 void remove_self_forwarding_pointers();
891 // Together, these store an object with a preserved mark, and its mark value.
892 Stack<oop, mtGC> _objs_with_preserved_marks;
893 Stack<markOop, mtGC> _preserved_marks_of_objs;
895 // Preserve the mark of "obj", if necessary, in preparation for its mark
896 // word being overwritten with a self-forwarding-pointer.
897 void preserve_mark_if_necessary(oop obj, markOop m);
899 // The stack of evac-failure objects left to be scanned.
900 GrowableArray<oop>* _evac_failure_scan_stack;
901 // The closure to apply to evac-failure objects.
903 OopsInHeapRegionClosure* _evac_failure_closure;
904 // Set the field above.
905 void
906 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
907 _evac_failure_closure = evac_failure_closure;
908 }
910 // Push "obj" on the scan stack.
911 void push_on_evac_failure_scan_stack(oop obj);
912 // Process scan stack entries until the stack is empty.
913 void drain_evac_failure_scan_stack();
914 // True iff an invocation of "drain_scan_stack" is in progress; to
915 // prevent unnecessary recursion.
916 bool _drain_in_progress;
918 // Do any necessary initialization for evacuation-failure handling.
919 // "cl" is the closure that will be used to process evac-failure
920 // objects.
921 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
922 // Do any necessary cleanup for evacuation-failure handling data
923 // structures.
924 void finalize_for_evac_failure();
926 // An attempt to evacuate "obj" has failed; take necessary steps.
927 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
928 void handle_evacuation_failure_common(oop obj, markOop m);
930 #ifndef PRODUCT
931 // Support for forcing evacuation failures. Analogous to
932 // PromotionFailureALot for the other collectors.
934 // Records whether G1EvacuationFailureALot should be in effect
935 // for the current GC
936 bool _evacuation_failure_alot_for_current_gc;
938 // Used to record the GC number for interval checking when
939 // determining whether G1EvaucationFailureALot is in effect
940 // for the current GC.
941 size_t _evacuation_failure_alot_gc_number;
943 // Count of the number of evacuations between failures.
944 volatile size_t _evacuation_failure_alot_count;
946 // Set whether G1EvacuationFailureALot should be in effect
947 // for the current GC (based upon the type of GC and which
948 // command line flags are set);
949 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
950 bool during_initial_mark,
951 bool during_marking);
953 inline void set_evacuation_failure_alot_for_current_gc();
955 // Return true if it's time to cause an evacuation failure.
956 inline bool evacuation_should_fail();
958 // Reset the G1EvacuationFailureALot counters. Should be called at
959 // the end of an evacuation pause in which an evacuation failure occurred.
960 inline void reset_evacuation_should_fail();
961 #endif // !PRODUCT
963 // ("Weak") Reference processing support.
964 //
965 // G1 has 2 instances of the reference processor class. One
966 // (_ref_processor_cm) handles reference object discovery
967 // and subsequent processing during concurrent marking cycles.
968 //
969 // The other (_ref_processor_stw) handles reference object
970 // discovery and processing during full GCs and incremental
971 // evacuation pauses.
972 //
973 // During an incremental pause, reference discovery will be
974 // temporarily disabled for _ref_processor_cm and will be
975 // enabled for _ref_processor_stw. At the end of the evacuation
976 // pause references discovered by _ref_processor_stw will be
977 // processed and discovery will be disabled. The previous
978 // setting for reference object discovery for _ref_processor_cm
979 // will be re-instated.
980 //
981 // At the start of marking:
982 // * Discovery by the CM ref processor is verified to be inactive
983 // and it's discovered lists are empty.
984 // * Discovery by the CM ref processor is then enabled.
985 //
986 // At the end of marking:
987 // * Any references on the CM ref processor's discovered
988 // lists are processed (possibly MT).
989 //
990 // At the start of full GC we:
991 // * Disable discovery by the CM ref processor and
992 // empty CM ref processor's discovered lists
993 // (without processing any entries).
994 // * Verify that the STW ref processor is inactive and it's
995 // discovered lists are empty.
996 // * Temporarily set STW ref processor discovery as single threaded.
997 // * Temporarily clear the STW ref processor's _is_alive_non_header
998 // field.
999 // * Finally enable discovery by the STW ref processor.
1000 //
1001 // The STW ref processor is used to record any discovered
1002 // references during the full GC.
1003 //
1004 // At the end of a full GC we:
1005 // * Enqueue any reference objects discovered by the STW ref processor
1006 // that have non-live referents. This has the side-effect of
1007 // making the STW ref processor inactive by disabling discovery.
1008 // * Verify that the CM ref processor is still inactive
1009 // and no references have been placed on it's discovered
1010 // lists (also checked as a precondition during initial marking).
1012 // The (stw) reference processor...
1013 ReferenceProcessor* _ref_processor_stw;
1015 STWGCTimer* _gc_timer_stw;
1016 ConcurrentGCTimer* _gc_timer_cm;
1018 G1OldTracer* _gc_tracer_cm;
1019 G1NewTracer* _gc_tracer_stw;
1021 // During reference object discovery, the _is_alive_non_header
1022 // closure (if non-null) is applied to the referent object to
1023 // determine whether the referent is live. If so then the
1024 // reference object does not need to be 'discovered' and can
1025 // be treated as a regular oop. This has the benefit of reducing
1026 // the number of 'discovered' reference objects that need to
1027 // be processed.
1028 //
1029 // Instance of the is_alive closure for embedding into the
1030 // STW reference processor as the _is_alive_non_header field.
1031 // Supplying a value for the _is_alive_non_header field is
1032 // optional but doing so prevents unnecessary additions to
1033 // the discovered lists during reference discovery.
1034 G1STWIsAliveClosure _is_alive_closure_stw;
1036 // The (concurrent marking) reference processor...
1037 ReferenceProcessor* _ref_processor_cm;
1039 // Instance of the concurrent mark is_alive closure for embedding
1040 // into the Concurrent Marking reference processor as the
1041 // _is_alive_non_header field. Supplying a value for the
1042 // _is_alive_non_header field is optional but doing so prevents
1043 // unnecessary additions to the discovered lists during reference
1044 // discovery.
1045 G1CMIsAliveClosure _is_alive_closure_cm;
1047 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1048 HeapRegion** _worker_cset_start_region;
1050 // Time stamp to validate the regions recorded in the cache
1051 // used by G1CollectedHeap::start_cset_region_for_worker().
1052 // The heap region entry for a given worker is valid iff
1053 // the associated time stamp value matches the current value
1054 // of G1CollectedHeap::_gc_time_stamp.
1055 unsigned int* _worker_cset_start_region_time_stamp;
1057 enum G1H_process_strong_roots_tasks {
1058 G1H_PS_filter_satb_buffers,
1059 G1H_PS_refProcessor_oops_do,
1060 // Leave this one last.
1061 G1H_PS_NumElements
1062 };
1064 SubTasksDone* _process_strong_tasks;
1066 volatile bool _free_regions_coming;
1068 public:
1070 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1072 void set_refine_cte_cl_concurrency(bool concurrent);
1074 RefToScanQueue *task_queue(int i) const;
1076 // A set of cards where updates happened during the GC
1077 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1079 // A DirtyCardQueueSet that is used to hold cards that contain
1080 // references into the current collection set. This is used to
1081 // update the remembered sets of the regions in the collection
1082 // set in the event of an evacuation failure.
1083 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1084 { return _into_cset_dirty_card_queue_set; }
1086 // Create a G1CollectedHeap with the specified policy.
1087 // Must call the initialize method afterwards.
1088 // May not return if something goes wrong.
1089 G1CollectedHeap(G1CollectorPolicy* policy);
1091 // Initialize the G1CollectedHeap to have the initial and
1092 // maximum sizes and remembered and barrier sets
1093 // specified by the policy object.
1094 jint initialize();
1096 // Return the (conservative) maximum heap alignment for any G1 heap
1097 static size_t conservative_max_heap_alignment();
1099 // Initialize weak reference processing.
1100 virtual void ref_processing_init();
1102 void set_par_threads(uint t) {
1103 SharedHeap::set_par_threads(t);
1104 // Done in SharedHeap but oddly there are
1105 // two _process_strong_tasks's in a G1CollectedHeap
1106 // so do it here too.
1107 _process_strong_tasks->set_n_threads(t);
1108 }
1110 // Set _n_par_threads according to a policy TBD.
1111 void set_par_threads();
1113 void set_n_termination(int t) {
1114 _process_strong_tasks->set_n_threads(t);
1115 }
1117 virtual CollectedHeap::Name kind() const {
1118 return CollectedHeap::G1CollectedHeap;
1119 }
1121 // The current policy object for the collector.
1122 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1124 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1126 // Adaptive size policy. No such thing for g1.
1127 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1129 // The rem set and barrier set.
1130 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1132 unsigned get_gc_time_stamp() {
1133 return _gc_time_stamp;
1134 }
1136 void reset_gc_time_stamp() {
1137 _gc_time_stamp = 0;
1138 OrderAccess::fence();
1139 // Clear the cached CSet starting regions and time stamps.
1140 // Their validity is dependent on the GC timestamp.
1141 clear_cset_start_regions();
1142 }
1144 void check_gc_time_stamps() PRODUCT_RETURN;
1146 void increment_gc_time_stamp() {
1147 ++_gc_time_stamp;
1148 OrderAccess::fence();
1149 }
1151 // Reset the given region's GC timestamp. If it's starts humongous,
1152 // also reset the GC timestamp of its corresponding
1153 // continues humongous regions too.
1154 void reset_gc_time_stamps(HeapRegion* hr);
1156 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1157 DirtyCardQueue* into_cset_dcq,
1158 bool concurrent, int worker_i);
1160 // The shared block offset table array.
1161 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1163 // Reference Processing accessors
1165 // The STW reference processor....
1166 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1168 // The Concurrent Marking reference processor...
1169 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1171 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1172 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1174 virtual size_t capacity() const;
1175 virtual size_t used() const;
1176 // This should be called when we're not holding the heap lock. The
1177 // result might be a bit inaccurate.
1178 size_t used_unlocked() const;
1179 size_t recalculate_used() const;
1181 // These virtual functions do the actual allocation.
1182 // Some heaps may offer a contiguous region for shared non-blocking
1183 // allocation, via inlined code (by exporting the address of the top and
1184 // end fields defining the extent of the contiguous allocation region.)
1185 // But G1CollectedHeap doesn't yet support this.
1187 // Return an estimate of the maximum allocation that could be performed
1188 // without triggering any collection or expansion activity. In a
1189 // generational collector, for example, this is probably the largest
1190 // allocation that could be supported (without expansion) in the youngest
1191 // generation. It is "unsafe" because no locks are taken; the result
1192 // should be treated as an approximation, not a guarantee, for use in
1193 // heuristic resizing decisions.
1194 virtual size_t unsafe_max_alloc();
1196 virtual bool is_maximal_no_gc() const {
1197 return _g1_storage.uncommitted_size() == 0;
1198 }
1200 // The total number of regions in the heap.
1201 uint n_regions() { return _hrs.length(); }
1203 // The max number of regions in the heap.
1204 uint max_regions() { return _hrs.max_length(); }
1206 // The number of regions that are completely free.
1207 uint free_regions() { return _free_list.length(); }
1209 // The number of regions that are not completely free.
1210 uint used_regions() { return n_regions() - free_regions(); }
1212 // The number of regions available for "regular" expansion.
1213 uint expansion_regions() { return _expansion_regions; }
1215 // Factory method for HeapRegion instances. It will return NULL if
1216 // the allocation fails.
1217 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1219 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1220 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1221 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1222 void verify_dirty_young_regions() PRODUCT_RETURN;
1224 // verify_region_sets() performs verification over the region
1225 // lists. It will be compiled in the product code to be used when
1226 // necessary (i.e., during heap verification).
1227 void verify_region_sets();
1229 // verify_region_sets_optional() is planted in the code for
1230 // list verification in non-product builds (and it can be enabled in
1231 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1232 #if HEAP_REGION_SET_FORCE_VERIFY
1233 void verify_region_sets_optional() {
1234 verify_region_sets();
1235 }
1236 #else // HEAP_REGION_SET_FORCE_VERIFY
1237 void verify_region_sets_optional() { }
1238 #endif // HEAP_REGION_SET_FORCE_VERIFY
1240 #ifdef ASSERT
1241 bool is_on_master_free_list(HeapRegion* hr) {
1242 return hr->containing_set() == &_free_list;
1243 }
1244 #endif // ASSERT
1246 // Wrapper for the region list operations that can be called from
1247 // methods outside this class.
1249 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1250 _secondary_free_list.add_as_tail(list);
1251 }
1253 void append_secondary_free_list() {
1254 _free_list.add_as_head(&_secondary_free_list);
1255 }
1257 void append_secondary_free_list_if_not_empty_with_lock() {
1258 // If the secondary free list looks empty there's no reason to
1259 // take the lock and then try to append it.
1260 if (!_secondary_free_list.is_empty()) {
1261 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1262 append_secondary_free_list();
1263 }
1264 }
1266 void old_set_remove(HeapRegion* hr) {
1267 _old_set.remove(hr);
1268 }
1270 size_t non_young_capacity_bytes() {
1271 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1272 }
1274 void set_free_regions_coming();
1275 void reset_free_regions_coming();
1276 bool free_regions_coming() { return _free_regions_coming; }
1277 void wait_while_free_regions_coming();
1279 // Determine whether the given region is one that we are using as an
1280 // old GC alloc region.
1281 bool is_old_gc_alloc_region(HeapRegion* hr) {
1282 return hr == _retained_old_gc_alloc_region;
1283 }
1285 // Perform a collection of the heap; intended for use in implementing
1286 // "System.gc". This probably implies as full a collection as the
1287 // "CollectedHeap" supports.
1288 virtual void collect(GCCause::Cause cause);
1290 // The same as above but assume that the caller holds the Heap_lock.
1291 void collect_locked(GCCause::Cause cause);
1293 // True iff an evacuation has failed in the most-recent collection.
1294 bool evacuation_failed() { return _evacuation_failed; }
1296 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1297 void prepend_to_freelist(FreeRegionList* list);
1298 void decrement_summary_bytes(size_t bytes);
1300 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1301 virtual bool is_in(const void* p) const;
1303 // Return "TRUE" iff the given object address is within the collection
1304 // set.
1305 inline bool obj_in_cs(oop obj);
1307 // Return "TRUE" iff the given object address is in the reserved
1308 // region of g1.
1309 bool is_in_g1_reserved(const void* p) const {
1310 return _g1_reserved.contains(p);
1311 }
1313 // Returns a MemRegion that corresponds to the space that has been
1314 // reserved for the heap
1315 MemRegion g1_reserved() {
1316 return _g1_reserved;
1317 }
1319 // Returns a MemRegion that corresponds to the space that has been
1320 // committed in the heap
1321 MemRegion g1_committed() {
1322 return _g1_committed;
1323 }
1325 virtual bool is_in_closed_subset(const void* p) const;
1327 G1SATBCardTableModRefBS* g1_barrier_set() {
1328 return (G1SATBCardTableModRefBS*) barrier_set();
1329 }
1331 // This resets the card table to all zeros. It is used after
1332 // a collection pause which used the card table to claim cards.
1333 void cleanUpCardTable();
1335 // Iteration functions.
1337 // Iterate over all the ref-containing fields of all objects, calling
1338 // "cl.do_oop" on each.
1339 virtual void oop_iterate(ExtendedOopClosure* cl);
1341 // Same as above, restricted to a memory region.
1342 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1344 // Iterate over all objects, calling "cl.do_object" on each.
1345 virtual void object_iterate(ObjectClosure* cl);
1347 virtual void safe_object_iterate(ObjectClosure* cl) {
1348 object_iterate(cl);
1349 }
1351 // Iterate over all spaces in use in the heap, in ascending address order.
1352 virtual void space_iterate(SpaceClosure* cl);
1354 // Iterate over heap regions, in address order, terminating the
1355 // iteration early if the "doHeapRegion" method returns "true".
1356 void heap_region_iterate(HeapRegionClosure* blk) const;
1358 // Return the region with the given index. It assumes the index is valid.
1359 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1361 // Divide the heap region sequence into "chunks" of some size (the number
1362 // of regions divided by the number of parallel threads times some
1363 // overpartition factor, currently 4). Assumes that this will be called
1364 // in parallel by ParallelGCThreads worker threads with discinct worker
1365 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1366 // calls will use the same "claim_value", and that that claim value is
1367 // different from the claim_value of any heap region before the start of
1368 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1369 // attempting to claim the first region in each chunk, and, if
1370 // successful, applying the closure to each region in the chunk (and
1371 // setting the claim value of the second and subsequent regions of the
1372 // chunk.) For now requires that "doHeapRegion" always returns "false",
1373 // i.e., that a closure never attempt to abort a traversal.
1374 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1375 uint worker,
1376 uint no_of_par_workers,
1377 jint claim_value);
1379 // It resets all the region claim values to the default.
1380 void reset_heap_region_claim_values();
1382 // Resets the claim values of regions in the current
1383 // collection set to the default.
1384 void reset_cset_heap_region_claim_values();
1386 #ifdef ASSERT
1387 bool check_heap_region_claim_values(jint claim_value);
1389 // Same as the routine above but only checks regions in the
1390 // current collection set.
1391 bool check_cset_heap_region_claim_values(jint claim_value);
1392 #endif // ASSERT
1394 // Clear the cached cset start regions and (more importantly)
1395 // the time stamps. Called when we reset the GC time stamp.
1396 void clear_cset_start_regions();
1398 // Given the id of a worker, obtain or calculate a suitable
1399 // starting region for iterating over the current collection set.
1400 HeapRegion* start_cset_region_for_worker(int worker_i);
1402 // This is a convenience method that is used by the
1403 // HeapRegionIterator classes to calculate the starting region for
1404 // each worker so that they do not all start from the same region.
1405 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1407 // Iterate over the regions (if any) in the current collection set.
1408 void collection_set_iterate(HeapRegionClosure* blk);
1410 // As above but starting from region r
1411 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1413 // Returns the first (lowest address) compactible space in the heap.
1414 virtual CompactibleSpace* first_compactible_space();
1416 // A CollectedHeap will contain some number of spaces. This finds the
1417 // space containing a given address, or else returns NULL.
1418 virtual Space* space_containing(const void* addr) const;
1420 // A G1CollectedHeap will contain some number of heap regions. This
1421 // finds the region containing a given address, or else returns NULL.
1422 template <class T>
1423 inline HeapRegion* heap_region_containing(const T addr) const;
1425 // Like the above, but requires "addr" to be in the heap (to avoid a
1426 // null-check), and unlike the above, may return an continuing humongous
1427 // region.
1428 template <class T>
1429 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1431 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1432 // each address in the (reserved) heap is a member of exactly
1433 // one block. The defining characteristic of a block is that it is
1434 // possible to find its size, and thus to progress forward to the next
1435 // block. (Blocks may be of different sizes.) Thus, blocks may
1436 // represent Java objects, or they might be free blocks in a
1437 // free-list-based heap (or subheap), as long as the two kinds are
1438 // distinguishable and the size of each is determinable.
1440 // Returns the address of the start of the "block" that contains the
1441 // address "addr". We say "blocks" instead of "object" since some heaps
1442 // may not pack objects densely; a chunk may either be an object or a
1443 // non-object.
1444 virtual HeapWord* block_start(const void* addr) const;
1446 // Requires "addr" to be the start of a chunk, and returns its size.
1447 // "addr + size" is required to be the start of a new chunk, or the end
1448 // of the active area of the heap.
1449 virtual size_t block_size(const HeapWord* addr) const;
1451 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1452 // the block is an object.
1453 virtual bool block_is_obj(const HeapWord* addr) const;
1455 // Does this heap support heap inspection? (+PrintClassHistogram)
1456 virtual bool supports_heap_inspection() const { return true; }
1458 // Section on thread-local allocation buffers (TLABs)
1459 // See CollectedHeap for semantics.
1461 bool supports_tlab_allocation() const;
1462 size_t tlab_capacity(Thread* ignored) const;
1463 size_t tlab_used(Thread* ignored) const;
1464 size_t max_tlab_size() const;
1465 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1467 // Can a compiler initialize a new object without store barriers?
1468 // This permission only extends from the creation of a new object
1469 // via a TLAB up to the first subsequent safepoint. If such permission
1470 // is granted for this heap type, the compiler promises to call
1471 // defer_store_barrier() below on any slow path allocation of
1472 // a new object for which such initializing store barriers will
1473 // have been elided. G1, like CMS, allows this, but should be
1474 // ready to provide a compensating write barrier as necessary
1475 // if that storage came out of a non-young region. The efficiency
1476 // of this implementation depends crucially on being able to
1477 // answer very efficiently in constant time whether a piece of
1478 // storage in the heap comes from a young region or not.
1479 // See ReduceInitialCardMarks.
1480 virtual bool can_elide_tlab_store_barriers() const {
1481 return true;
1482 }
1484 virtual bool card_mark_must_follow_store() const {
1485 return true;
1486 }
1488 bool is_in_young(const oop obj) {
1489 HeapRegion* hr = heap_region_containing(obj);
1490 return hr != NULL && hr->is_young();
1491 }
1493 #ifdef ASSERT
1494 virtual bool is_in_partial_collection(const void* p);
1495 #endif
1497 virtual bool is_scavengable(const void* addr);
1499 // We don't need barriers for initializing stores to objects
1500 // in the young gen: for the SATB pre-barrier, there is no
1501 // pre-value that needs to be remembered; for the remembered-set
1502 // update logging post-barrier, we don't maintain remembered set
1503 // information for young gen objects.
1504 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1505 return is_in_young(new_obj);
1506 }
1508 // Returns "true" iff the given word_size is "very large".
1509 static bool isHumongous(size_t word_size) {
1510 // Note this has to be strictly greater-than as the TLABs
1511 // are capped at the humongous thresold and we want to
1512 // ensure that we don't try to allocate a TLAB as
1513 // humongous and that we don't allocate a humongous
1514 // object in a TLAB.
1515 return word_size > _humongous_object_threshold_in_words;
1516 }
1518 // Update mod union table with the set of dirty cards.
1519 void updateModUnion();
1521 // Set the mod union bits corresponding to the given memRegion. Note
1522 // that this is always a safe operation, since it doesn't clear any
1523 // bits.
1524 void markModUnionRange(MemRegion mr);
1526 // Records the fact that a marking phase is no longer in progress.
1527 void set_marking_complete() {
1528 _mark_in_progress = false;
1529 }
1530 void set_marking_started() {
1531 _mark_in_progress = true;
1532 }
1533 bool mark_in_progress() {
1534 return _mark_in_progress;
1535 }
1537 // Print the maximum heap capacity.
1538 virtual size_t max_capacity() const;
1540 virtual jlong millis_since_last_gc();
1543 // Convenience function to be used in situations where the heap type can be
1544 // asserted to be this type.
1545 static G1CollectedHeap* heap();
1547 void set_region_short_lived_locked(HeapRegion* hr);
1548 // add appropriate methods for any other surv rate groups
1550 YoungList* young_list() const { return _young_list; }
1552 // debugging
1553 bool check_young_list_well_formed() {
1554 return _young_list->check_list_well_formed();
1555 }
1557 bool check_young_list_empty(bool check_heap,
1558 bool check_sample = true);
1560 // *** Stuff related to concurrent marking. It's not clear to me that so
1561 // many of these need to be public.
1563 // The functions below are helper functions that a subclass of
1564 // "CollectedHeap" can use in the implementation of its virtual
1565 // functions.
1566 // This performs a concurrent marking of the live objects in a
1567 // bitmap off to the side.
1568 void doConcurrentMark();
1570 bool isMarkedPrev(oop obj) const;
1571 bool isMarkedNext(oop obj) const;
1573 // Determine if an object is dead, given the object and also
1574 // the region to which the object belongs. An object is dead
1575 // iff a) it was not allocated since the last mark and b) it
1576 // is not marked.
1578 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1579 return
1580 !hr->obj_allocated_since_prev_marking(obj) &&
1581 !isMarkedPrev(obj);
1582 }
1584 // This function returns true when an object has been
1585 // around since the previous marking and hasn't yet
1586 // been marked during this marking.
1588 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1589 return
1590 !hr->obj_allocated_since_next_marking(obj) &&
1591 !isMarkedNext(obj);
1592 }
1594 // Determine if an object is dead, given only the object itself.
1595 // This will find the region to which the object belongs and
1596 // then call the region version of the same function.
1598 // Added if it is NULL it isn't dead.
1600 bool is_obj_dead(const oop obj) const {
1601 const HeapRegion* hr = heap_region_containing(obj);
1602 if (hr == NULL) {
1603 if (obj == NULL) return false;
1604 else return true;
1605 }
1606 else return is_obj_dead(obj, hr);
1607 }
1609 bool is_obj_ill(const oop obj) const {
1610 const HeapRegion* hr = heap_region_containing(obj);
1611 if (hr == NULL) {
1612 if (obj == NULL) return false;
1613 else return true;
1614 }
1615 else return is_obj_ill(obj, hr);
1616 }
1618 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1619 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1620 bool is_marked(oop obj, VerifyOption vo);
1621 const char* top_at_mark_start_str(VerifyOption vo);
1623 ConcurrentMark* concurrent_mark() const { return _cm; }
1625 // Refinement
1627 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1629 // The dirty cards region list is used to record a subset of regions
1630 // whose cards need clearing. The list if populated during the
1631 // remembered set scanning and drained during the card table
1632 // cleanup. Although the methods are reentrant, population/draining
1633 // phases must not overlap. For synchronization purposes the last
1634 // element on the list points to itself.
1635 HeapRegion* _dirty_cards_region_list;
1636 void push_dirty_cards_region(HeapRegion* hr);
1637 HeapRegion* pop_dirty_cards_region();
1639 // Optimized nmethod scanning support routines
1641 // Register the given nmethod with the G1 heap
1642 virtual void register_nmethod(nmethod* nm);
1644 // Unregister the given nmethod from the G1 heap
1645 virtual void unregister_nmethod(nmethod* nm);
1647 // Migrate the nmethods in the code root lists of the regions
1648 // in the collection set to regions in to-space. In the event
1649 // of an evacuation failure, nmethods that reference objects
1650 // that were not successfullly evacuated are not migrated.
1651 void migrate_strong_code_roots();
1653 // Free up superfluous code root memory.
1654 void purge_code_root_memory();
1656 // During an initial mark pause, mark all the code roots that
1657 // point into regions *not* in the collection set.
1658 void mark_strong_code_roots(uint worker_id);
1660 // Rebuild the stong code root lists for each region
1661 // after a full GC
1662 void rebuild_strong_code_roots();
1664 // Delete entries for dead interned string and clean up unreferenced symbols
1665 // in symbol table, possibly in parallel.
1666 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1668 // Redirty logged cards in the refinement queue.
1669 void redirty_logged_cards();
1670 // Verification
1672 // The following is just to alert the verification code
1673 // that a full collection has occurred and that the
1674 // remembered sets are no longer up to date.
1675 bool _full_collection;
1676 void set_full_collection() { _full_collection = true;}
1677 void clear_full_collection() {_full_collection = false;}
1678 bool full_collection() {return _full_collection;}
1680 // Perform any cleanup actions necessary before allowing a verification.
1681 virtual void prepare_for_verify();
1683 // Perform verification.
1685 // vo == UsePrevMarking -> use "prev" marking information,
1686 // vo == UseNextMarking -> use "next" marking information
1687 // vo == UseMarkWord -> use the mark word in the object header
1688 //
1689 // NOTE: Only the "prev" marking information is guaranteed to be
1690 // consistent most of the time, so most calls to this should use
1691 // vo == UsePrevMarking.
1692 // Currently, there is only one case where this is called with
1693 // vo == UseNextMarking, which is to verify the "next" marking
1694 // information at the end of remark.
1695 // Currently there is only one place where this is called with
1696 // vo == UseMarkWord, which is to verify the marking during a
1697 // full GC.
1698 void verify(bool silent, VerifyOption vo);
1700 // Override; it uses the "prev" marking information
1701 virtual void verify(bool silent);
1703 // The methods below are here for convenience and dispatch the
1704 // appropriate method depending on value of the given VerifyOption
1705 // parameter. The values for that parameter, and their meanings,
1706 // are the same as those above.
1708 bool is_obj_dead_cond(const oop obj,
1709 const HeapRegion* hr,
1710 const VerifyOption vo) const {
1711 switch (vo) {
1712 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1713 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1714 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1715 default: ShouldNotReachHere();
1716 }
1717 return false; // keep some compilers happy
1718 }
1720 bool is_obj_dead_cond(const oop obj,
1721 const VerifyOption vo) const {
1722 switch (vo) {
1723 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1724 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1725 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1726 default: ShouldNotReachHere();
1727 }
1728 return false; // keep some compilers happy
1729 }
1731 // Printing
1733 virtual void print_on(outputStream* st) const;
1734 virtual void print_extended_on(outputStream* st) const;
1735 virtual void print_on_error(outputStream* st) const;
1737 virtual void print_gc_threads_on(outputStream* st) const;
1738 virtual void gc_threads_do(ThreadClosure* tc) const;
1740 // Override
1741 void print_tracing_info() const;
1743 // The following two methods are helpful for debugging RSet issues.
1744 void print_cset_rsets() PRODUCT_RETURN;
1745 void print_all_rsets() PRODUCT_RETURN;
1747 public:
1748 void stop_conc_gc_threads();
1750 size_t pending_card_num();
1751 size_t cards_scanned();
1753 protected:
1754 size_t _max_heap_capacity;
1755 };
1757 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1758 private:
1759 bool _retired;
1761 public:
1762 G1ParGCAllocBuffer(size_t gclab_word_size);
1764 void set_buf(HeapWord* buf) {
1765 ParGCAllocBuffer::set_buf(buf);
1766 _retired = false;
1767 }
1769 void retire(bool end_of_gc, bool retain) {
1770 if (_retired)
1771 return;
1772 ParGCAllocBuffer::retire(end_of_gc, retain);
1773 _retired = true;
1774 }
1775 };
1777 class G1ParScanThreadState : public StackObj {
1778 protected:
1779 G1CollectedHeap* _g1h;
1780 RefToScanQueue* _refs;
1781 DirtyCardQueue _dcq;
1782 G1SATBCardTableModRefBS* _ct_bs;
1783 G1RemSet* _g1_rem;
1785 G1ParGCAllocBuffer _surviving_alloc_buffer;
1786 G1ParGCAllocBuffer _tenured_alloc_buffer;
1787 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1788 ageTable _age_table;
1790 G1ParScanClosure _scanner;
1792 size_t _alloc_buffer_waste;
1793 size_t _undo_waste;
1795 OopsInHeapRegionClosure* _evac_failure_cl;
1797 int _hash_seed;
1798 uint _queue_num;
1800 size_t _term_attempts;
1802 double _start;
1803 double _start_strong_roots;
1804 double _strong_roots_time;
1805 double _start_term;
1806 double _term_time;
1808 // Map from young-age-index (0 == not young, 1 is youngest) to
1809 // surviving words. base is what we get back from the malloc call
1810 size_t* _surviving_young_words_base;
1811 // this points into the array, as we use the first few entries for padding
1812 size_t* _surviving_young_words;
1814 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1816 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1818 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1820 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1821 G1SATBCardTableModRefBS* ctbs() { return _ct_bs; }
1823 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1824 if (!from->is_survivor()) {
1825 _g1_rem->par_write_ref(from, p, tid);
1826 }
1827 }
1829 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1830 // If the new value of the field points to the same region or
1831 // is the to-space, we don't need to include it in the Rset updates.
1832 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1833 size_t card_index = ctbs()->index_for(p);
1834 // If the card hasn't been added to the buffer, do it.
1835 if (ctbs()->mark_card_deferred(card_index)) {
1836 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1837 }
1838 }
1839 }
1841 public:
1842 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp);
1844 ~G1ParScanThreadState() {
1845 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1846 }
1848 RefToScanQueue* refs() { return _refs; }
1849 ageTable* age_table() { return &_age_table; }
1851 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1852 return _alloc_buffers[purpose];
1853 }
1855 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1856 size_t undo_waste() const { return _undo_waste; }
1858 #ifdef ASSERT
1859 bool verify_ref(narrowOop* ref) const;
1860 bool verify_ref(oop* ref) const;
1861 bool verify_task(StarTask ref) const;
1862 #endif // ASSERT
1864 template <class T> void push_on_queue(T* ref) {
1865 assert(verify_ref(ref), "sanity");
1866 refs()->push(ref);
1867 }
1869 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1870 if (G1DeferredRSUpdate) {
1871 deferred_rs_update(from, p, tid);
1872 } else {
1873 immediate_rs_update(from, p, tid);
1874 }
1875 }
1877 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1878 HeapWord* obj = NULL;
1879 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1880 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1881 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1882 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1883 alloc_buf->retire(false /* end_of_gc */, false /* retain */);
1885 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1886 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1887 // Otherwise.
1888 alloc_buf->set_word_size(gclab_word_size);
1889 alloc_buf->set_buf(buf);
1891 obj = alloc_buf->allocate(word_sz);
1892 assert(obj != NULL, "buffer was definitely big enough...");
1893 } else {
1894 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1895 }
1896 return obj;
1897 }
1899 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1900 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1901 if (obj != NULL) return obj;
1902 return allocate_slow(purpose, word_sz);
1903 }
1905 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1906 if (alloc_buffer(purpose)->contains(obj)) {
1907 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1908 "should contain whole object");
1909 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1910 } else {
1911 CollectedHeap::fill_with_object(obj, word_sz);
1912 add_to_undo_waste(word_sz);
1913 }
1914 }
1916 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1917 _evac_failure_cl = evac_failure_cl;
1918 }
1919 OopsInHeapRegionClosure* evac_failure_closure() {
1920 return _evac_failure_cl;
1921 }
1923 int* hash_seed() { return &_hash_seed; }
1924 uint queue_num() { return _queue_num; }
1926 size_t term_attempts() const { return _term_attempts; }
1927 void note_term_attempt() { _term_attempts++; }
1929 void start_strong_roots() {
1930 _start_strong_roots = os::elapsedTime();
1931 }
1932 void end_strong_roots() {
1933 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1934 }
1935 double strong_roots_time() const { return _strong_roots_time; }
1937 void start_term_time() {
1938 note_term_attempt();
1939 _start_term = os::elapsedTime();
1940 }
1941 void end_term_time() {
1942 _term_time += (os::elapsedTime() - _start_term);
1943 }
1944 double term_time() const { return _term_time; }
1946 double elapsed_time() const {
1947 return os::elapsedTime() - _start;
1948 }
1950 static void
1951 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1952 void
1953 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1955 size_t* surviving_young_words() {
1956 // We add on to hide entry 0 which accumulates surviving words for
1957 // age -1 regions (i.e. non-young ones)
1958 return _surviving_young_words;
1959 }
1961 void retire_alloc_buffers() {
1962 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1963 size_t waste = _alloc_buffers[ap]->words_remaining();
1964 add_to_alloc_buffer_waste(waste);
1965 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
1966 true /* end_of_gc */,
1967 false /* retain */);
1968 }
1969 }
1970 private:
1971 #define G1_PARTIAL_ARRAY_MASK 0x2
1973 inline bool has_partial_array_mask(oop* ref) const {
1974 return ((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) == G1_PARTIAL_ARRAY_MASK;
1975 }
1977 // We never encode partial array oops as narrowOop*, so return false immediately.
1978 // This allows the compiler to create optimized code when popping references from
1979 // the work queue.
1980 inline bool has_partial_array_mask(narrowOop* ref) const {
1981 assert(((uintptr_t)ref & G1_PARTIAL_ARRAY_MASK) != G1_PARTIAL_ARRAY_MASK, "Partial array oop reference encoded as narrowOop*");
1982 return false;
1983 }
1985 // Only implement set_partial_array_mask() for regular oops, not for narrowOops.
1986 // We always encode partial arrays as regular oop, to allow the
1987 // specialization for has_partial_array_mask() for narrowOops above.
1988 // This means that unintentional use of this method with narrowOops are caught
1989 // by the compiler.
1990 inline oop* set_partial_array_mask(oop obj) const {
1991 assert(((uintptr_t)(void *)obj & G1_PARTIAL_ARRAY_MASK) == 0, "Information loss!");
1992 return (oop*) ((uintptr_t)(void *)obj | G1_PARTIAL_ARRAY_MASK);
1993 }
1995 inline oop clear_partial_array_mask(oop* ref) const {
1996 return cast_to_oop((intptr_t)ref & ~G1_PARTIAL_ARRAY_MASK);
1997 }
1999 void do_oop_partial_array(oop* p) {
2000 assert(has_partial_array_mask(p), "invariant");
2001 oop from_obj = clear_partial_array_mask(p);
2003 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
2004 assert(from_obj->is_objArray(), "must be obj array");
2005 objArrayOop from_obj_array = objArrayOop(from_obj);
2006 // The from-space object contains the real length.
2007 int length = from_obj_array->length();
2009 assert(from_obj->is_forwarded(), "must be forwarded");
2010 oop to_obj = from_obj->forwardee();
2011 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
2012 objArrayOop to_obj_array = objArrayOop(to_obj);
2013 // We keep track of the next start index in the length field of the
2014 // to-space object.
2015 int next_index = to_obj_array->length();
2016 assert(0 <= next_index && next_index < length,
2017 err_msg("invariant, next index: %d, length: %d", next_index, length));
2019 int start = next_index;
2020 int end = length;
2021 int remainder = end - start;
2022 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
2023 if (remainder > 2 * ParGCArrayScanChunk) {
2024 end = start + ParGCArrayScanChunk;
2025 to_obj_array->set_length(end);
2026 // Push the remainder before we process the range in case another
2027 // worker has run out of things to do and can steal it.
2028 oop* from_obj_p = set_partial_array_mask(from_obj);
2029 push_on_queue(from_obj_p);
2030 } else {
2031 assert(length == end, "sanity");
2032 // We'll process the final range for this object. Restore the length
2033 // so that the heap remains parsable in case of evacuation failure.
2034 to_obj_array->set_length(end);
2035 }
2036 _scanner.set_region(_g1h->heap_region_containing_raw(to_obj));
2037 // Process indexes [start,end). It will also process the header
2038 // along with the first chunk (i.e., the chunk with start == 0).
2039 // Note that at this point the length field of to_obj_array is not
2040 // correct given that we are using it to keep track of the next
2041 // start index. oop_iterate_range() (thankfully!) ignores the length
2042 // field and only relies on the start / end parameters. It does
2043 // however return the size of the object which will be incorrect. So
2044 // we have to ignore it even if we wanted to use it.
2045 to_obj_array->oop_iterate_range(&_scanner, start, end);
2046 }
2048 // This method is applied to the fields of the objects that have just been copied.
2049 template <class T> void do_oop_evac(T* p, HeapRegion* from) {
2050 assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
2051 "Reference should not be NULL here as such are never pushed to the task queue.");
2052 oop obj = oopDesc::load_decode_heap_oop_not_null(p);
2054 // Although we never intentionally push references outside of the collection
2055 // set, due to (benign) races in the claim mechanism during RSet scanning more
2056 // than one thread might claim the same card. So the same card may be
2057 // processed multiple times. So redo this check.
2058 if (_g1h->in_cset_fast_test(obj)) {
2059 oop forwardee;
2060 if (obj->is_forwarded()) {
2061 forwardee = obj->forwardee();
2062 } else {
2063 forwardee = copy_to_survivor_space(obj);
2064 }
2065 assert(forwardee != NULL, "forwardee should not be NULL");
2066 oopDesc::encode_store_heap_oop(p, forwardee);
2067 }
2069 assert(obj != NULL, "Must be");
2070 update_rs(from, p, queue_num());
2071 }
2072 public:
2074 oop copy_to_survivor_space(oop const obj);
2076 template <class T> void deal_with_reference(T* ref_to_scan) {
2077 if (!has_partial_array_mask(ref_to_scan)) {
2078 // Note: we can use "raw" versions of "region_containing" because
2079 // "obj_to_scan" is definitely in the heap, and is not in a
2080 // humongous region.
2081 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2082 do_oop_evac(ref_to_scan, r);
2083 } else {
2084 do_oop_partial_array((oop*)ref_to_scan);
2085 }
2086 }
2088 void deal_with_reference(StarTask ref) {
2089 assert(verify_task(ref), "sanity");
2090 if (ref.is_narrow()) {
2091 deal_with_reference((narrowOop*)ref);
2092 } else {
2093 deal_with_reference((oop*)ref);
2094 }
2095 }
2097 public:
2098 void trim_queue();
2099 };
2101 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP