1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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).
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
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/g1YCTypes.hpp"
35 #include "gc_implementation/g1/heapRegionSeq.hpp"
36 #include "gc_implementation/g1/heapRegionSets.hpp"
37 #include "gc_implementation/shared/hSpaceCounters.hpp"
38 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
39 #include "memory/barrierSet.hpp"
40 #include "memory/memRegion.hpp"
41 #include "memory/sharedHeap.hpp"
42 #include "utilities/stack.hpp"
43
44 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
45 // It uses the "Garbage First" heap organization and algorithm, which
46 // may combine concurrent marking with parallel, incremental compaction of
47 // heap subsets that will yield large amounts of garbage.
48
49 // Forward declarations
50 class HeapRegion;
51 class HRRSCleanupTask;
52 class GenerationSpec;
53 class OopsInHeapRegionClosure;
54 class G1KlassScanClosure;
55 class G1ScanHeapEvacClosure;
56 class ObjectClosure;
57 class SpaceClosure;
58 class CompactibleSpaceClosure;
59 class Space;
60 class G1CollectorPolicy;
61 class GenRemSet;
62 class G1RemSet;
63 class HeapRegionRemSetIterator;
64 class ConcurrentMark;
65 class ConcurrentMarkThread;
66 class ConcurrentG1Refine;
67 class ConcurrentGCTimer;
68 class GenerationCounters;
69 class STWGCTimer;
70 class G1NewTracer;
71 class G1OldTracer;
72 class EvacuationFailedInfo;
73 class nmethod;
74
75 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
76 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
77
78 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
79 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
80
81 enum GCAllocPurpose {
82 GCAllocForTenured,
83 GCAllocForSurvived,
84 GCAllocPurposeCount
85 };
86
87 class YoungList : public CHeapObj<mtGC> {
88 private:
89 G1CollectedHeap* _g1h;
90
91 HeapRegion* _head;
92
93 HeapRegion* _survivor_head;
94 HeapRegion* _survivor_tail;
95
96 HeapRegion* _curr;
97
98 uint _length;
99 uint _survivor_length;
100
101 size_t _last_sampled_rs_lengths;
102 size_t _sampled_rs_lengths;
103
104 void empty_list(HeapRegion* list);
105
106 public:
107 YoungList(G1CollectedHeap* g1h);
108
109 void push_region(HeapRegion* hr);
110 void add_survivor_region(HeapRegion* hr);
111
112 void empty_list();
113 bool is_empty() { return _length == 0; }
114 uint length() { return _length; }
115 uint survivor_length() { return _survivor_length; }
116
117 // Currently we do not keep track of the used byte sum for the
118 // young list and the survivors and it'd be quite a lot of work to
119 // do so. When we'll eventually replace the young list with
120 // instances of HeapRegionLinkedList we'll get that for free. So,
121 // we'll report the more accurate information then.
122 size_t eden_used_bytes() {
123 assert(length() >= survivor_length(), "invariant");
124 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
125 }
126 size_t survivor_used_bytes() {
127 return (size_t) survivor_length() * HeapRegion::GrainBytes;
128 }
129
130 void rs_length_sampling_init();
131 bool rs_length_sampling_more();
132 void rs_length_sampling_next();
133
134 void reset_sampled_info() {
135 _last_sampled_rs_lengths = 0;
136 }
137 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
138
139 // for development purposes
140 void reset_auxilary_lists();
141 void clear() { _head = NULL; _length = 0; }
142
143 void clear_survivors() {
144 _survivor_head = NULL;
145 _survivor_tail = NULL;
146 _survivor_length = 0;
147 }
148
149 HeapRegion* first_region() { return _head; }
150 HeapRegion* first_survivor_region() { return _survivor_head; }
151 HeapRegion* last_survivor_region() { return _survivor_tail; }
152
153 // debugging
154 bool check_list_well_formed();
155 bool check_list_empty(bool check_sample = true);
156 void print();
157 };
158
159 class MutatorAllocRegion : public G1AllocRegion {
160 protected:
161 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
162 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
163 public:
164 MutatorAllocRegion()
165 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
166 };
167
168 class SurvivorGCAllocRegion : public G1AllocRegion {
169 protected:
170 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
171 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
172 public:
173 SurvivorGCAllocRegion()
174 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
175 };
176
177 class OldGCAllocRegion : public G1AllocRegion {
178 protected:
179 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
180 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
181 public:
182 OldGCAllocRegion()
183 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
184 };
185
186 // The G1 STW is alive closure.
187 // An instance is embedded into the G1CH and used as the
188 // (optional) _is_alive_non_header closure in the STW
189 // reference processor. It is also extensively used during
190 // reference processing during STW evacuation pauses.
191 class G1STWIsAliveClosure: public BoolObjectClosure {
192 G1CollectedHeap* _g1;
193 public:
194 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
195 bool do_object_b(oop p);
196 };
197
198 class RefineCardTableEntryClosure;
199
200 class G1CollectedHeap : public SharedHeap {
201 friend class VM_G1CollectForAllocation;
202 friend class VM_G1CollectFull;
203 friend class VM_G1IncCollectionPause;
204 friend class VMStructs;
205 friend class MutatorAllocRegion;
206 friend class SurvivorGCAllocRegion;
207 friend class OldGCAllocRegion;
208
209 // Closures used in implementation.
210 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
211 friend class G1ParCopyClosure;
212 friend class G1IsAliveClosure;
213 friend class G1EvacuateFollowersClosure;
214 friend class G1ParScanThreadState;
215 friend class G1ParScanClosureSuper;
216 friend class G1ParEvacuateFollowersClosure;
217 friend class G1ParTask;
218 friend class G1FreeGarbageRegionClosure;
219 friend class RefineCardTableEntryClosure;
220 friend class G1PrepareCompactClosure;
221 friend class RegionSorter;
222 friend class RegionResetter;
223 friend class CountRCClosure;
224 friend class EvacPopObjClosure;
225 friend class G1ParCleanupCTTask;
226
227 // Other related classes.
228 friend class G1MarkSweep;
229
230 private:
231 // The one and only G1CollectedHeap, so static functions can find it.
232 static G1CollectedHeap* _g1h;
233
234 static size_t _humongous_object_threshold_in_words;
235
236 // Storage for the G1 heap.
237 VirtualSpace _g1_storage;
238 MemRegion _g1_reserved;
239
240 // The part of _g1_storage that is currently committed.
241 MemRegion _g1_committed;
242
243 // The master free list. It will satisfy all new region allocations.
244 MasterFreeRegionList _free_list;
245
246 // The secondary free list which contains regions that have been
247 // freed up during the cleanup process. This will be appended to the
248 // master free list when appropriate.
249 SecondaryFreeRegionList _secondary_free_list;
250
251 // It keeps track of the old regions.
252 MasterOldRegionSet _old_set;
253
254 // It keeps track of the humongous regions.
255 MasterHumongousRegionSet _humongous_set;
256
257 // The number of regions we could create by expansion.
258 uint _expansion_regions;
259
260 // The block offset table for the G1 heap.
261 G1BlockOffsetSharedArray* _bot_shared;
262
263 // Tears down the region sets / lists so that they are empty and the
264 // regions on the heap do not belong to a region set / list. The
265 // only exception is the humongous set which we leave unaltered. If
266 // free_list_only is true, it will only tear down the master free
267 // list. It is called before a Full GC (free_list_only == false) or
268 // before heap shrinking (free_list_only == true).
269 void tear_down_region_sets(bool free_list_only);
270
271 // Rebuilds the region sets / lists so that they are repopulated to
272 // reflect the contents of the heap. The only exception is the
273 // humongous set which was not torn down in the first place. If
274 // free_list_only is true, it will only rebuild the master free
275 // list. It is called after a Full GC (free_list_only == false) or
276 // after heap shrinking (free_list_only == true).
277 void rebuild_region_sets(bool free_list_only);
278
279 // The sequence of all heap regions in the heap.
280 HeapRegionSeq _hrs;
281
282 // Alloc region used to satisfy mutator allocation requests.
283 MutatorAllocRegion _mutator_alloc_region;
284
285 // Alloc region used to satisfy allocation requests by the GC for
286 // survivor objects.
287 SurvivorGCAllocRegion _survivor_gc_alloc_region;
288
289 // PLAB sizing policy for survivors.
290 PLABStats _survivor_plab_stats;
291
292 // Alloc region used to satisfy allocation requests by the GC for
293 // old objects.
294 OldGCAllocRegion _old_gc_alloc_region;
295
296 // PLAB sizing policy for tenured objects.
297 PLABStats _old_plab_stats;
298
299 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
300 PLABStats* stats = NULL;
301
302 switch (purpose) {
303 case GCAllocForSurvived:
304 stats = &_survivor_plab_stats;
305 break;
306 case GCAllocForTenured:
307 stats = &_old_plab_stats;
308 break;
309 default:
310 assert(false, "unrecognized GCAllocPurpose");
311 }
312
313 return stats;
314 }
315
316 // The last old region we allocated to during the last GC.
317 // Typically, it is not full so we should re-use it during the next GC.
318 HeapRegion* _retained_old_gc_alloc_region;
319
320 // It specifies whether we should attempt to expand the heap after a
321 // region allocation failure. If heap expansion fails we set this to
322 // false so that we don't re-attempt the heap expansion (it's likely
323 // that subsequent expansion attempts will also fail if one fails).
324 // Currently, it is only consulted during GC and it's reset at the
325 // start of each GC.
326 bool _expand_heap_after_alloc_failure;
327
328 // It resets the mutator alloc region before new allocations can take place.
329 void init_mutator_alloc_region();
330
331 // It releases the mutator alloc region.
332 void release_mutator_alloc_region();
333
334 // It initializes the GC alloc regions at the start of a GC.
335 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
336
337 // It releases the GC alloc regions at the end of a GC.
338 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
339
340 // It does any cleanup that needs to be done on the GC alloc regions
341 // before a Full GC.
342 void abandon_gc_alloc_regions();
343
344 // Helper for monitoring and management support.
345 G1MonitoringSupport* _g1mm;
346
347 // Determines PLAB size for a particular allocation purpose.
348 size_t desired_plab_sz(GCAllocPurpose purpose);
349
350 // Outside of GC pauses, the number of bytes used in all regions other
351 // than the current allocation region.
352 size_t _summary_bytes_used;
353
354 // This is used for a quick test on whether a reference points into
355 // the collection set or not. Basically, we have an array, with one
356 // byte per region, and that byte denotes whether the corresponding
357 // region is in the collection set or not. The entry corresponding
358 // the bottom of the heap, i.e., region 0, is pointed to by
359 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
360 // biased so that it actually points to address 0 of the address
361 // space, to make the test as fast as possible (we can simply shift
362 // the address to address into it, instead of having to subtract the
363 // bottom of the heap from the address before shifting it; basically
364 // it works in the same way the card table works).
365 bool* _in_cset_fast_test;
366
367 // The allocated array used for the fast test on whether a reference
368 // points into the collection set or not. This field is also used to
369 // free the array.
370 bool* _in_cset_fast_test_base;
371
372 // The length of the _in_cset_fast_test_base array.
373 uint _in_cset_fast_test_length;
374
375 volatile unsigned _gc_time_stamp;
376
377 size_t* _surviving_young_words;
378
379 G1HRPrinter _hr_printer;
380
381 void setup_surviving_young_words();
382 void update_surviving_young_words(size_t* surv_young_words);
383 void cleanup_surviving_young_words();
384
385 // It decides whether an explicit GC should start a concurrent cycle
386 // instead of doing a STW GC. Currently, a concurrent cycle is
387 // explicitly started if:
388 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
389 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
390 // (c) cause == _g1_humongous_allocation
391 bool should_do_concurrent_full_gc(GCCause::Cause cause);
392
393 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
394 // concurrent cycles) we have started.
395 volatile unsigned int _old_marking_cycles_started;
396
397 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
398 // concurrent cycles) we have completed.
399 volatile unsigned int _old_marking_cycles_completed;
400
401 bool _concurrent_cycle_started;
402
403 // This is a non-product method that is helpful for testing. It is
404 // called at the end of a GC and artificially expands the heap by
405 // allocating a number of dead regions. This way we can induce very
406 // frequent marking cycles and stress the cleanup / concurrent
407 // cleanup code more (as all the regions that will be allocated by
408 // this method will be found dead by the marking cycle).
409 void allocate_dummy_regions() PRODUCT_RETURN;
410
411 // Clear RSets after a compaction. It also resets the GC time stamps.
412 void clear_rsets_post_compaction();
413
414 // If the HR printer is active, dump the state of the regions in the
415 // heap after a compaction.
416 void print_hrs_post_compaction();
417
418 double verify(bool guard, const char* msg);
419 void verify_before_gc();
420 void verify_after_gc();
421
422 void log_gc_header();
423 void log_gc_footer(double pause_time_sec);
424
425 // These are macros so that, if the assert fires, we get the correct
426 // line number, file, etc.
427
428 #define heap_locking_asserts_err_msg(_extra_message_) \
429 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
430 (_extra_message_), \
431 BOOL_TO_STR(Heap_lock->owned_by_self()), \
432 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
433 BOOL_TO_STR(Thread::current()->is_VM_thread()))
434
435 #define assert_heap_locked() \
436 do { \
437 assert(Heap_lock->owned_by_self(), \
438 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
439 } while (0)
440
441 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
442 do { \
443 assert(Heap_lock->owned_by_self() || \
444 (SafepointSynchronize::is_at_safepoint() && \
445 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
446 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
447 "should be at a safepoint")); \
448 } while (0)
449
450 #define assert_heap_locked_and_not_at_safepoint() \
451 do { \
452 assert(Heap_lock->owned_by_self() && \
453 !SafepointSynchronize::is_at_safepoint(), \
454 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
455 "should not be at a safepoint")); \
456 } while (0)
457
458 #define assert_heap_not_locked() \
459 do { \
460 assert(!Heap_lock->owned_by_self(), \
461 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
462 } while (0)
463
464 #define assert_heap_not_locked_and_not_at_safepoint() \
465 do { \
466 assert(!Heap_lock->owned_by_self() && \
467 !SafepointSynchronize::is_at_safepoint(), \
468 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
469 "should not be at a safepoint")); \
470 } while (0)
471
472 #define assert_at_safepoint(_should_be_vm_thread_) \
473 do { \
474 assert(SafepointSynchronize::is_at_safepoint() && \
475 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
476 heap_locking_asserts_err_msg("should be at a safepoint")); \
477 } while (0)
478
479 #define assert_not_at_safepoint() \
480 do { \
481 assert(!SafepointSynchronize::is_at_safepoint(), \
482 heap_locking_asserts_err_msg("should not be at a safepoint")); \
483 } while (0)
484
485 protected:
486
487 // The young region list.
488 YoungList* _young_list;
489
490 // The current policy object for the collector.
491 G1CollectorPolicy* _g1_policy;
492
493 // This is the second level of trying to allocate a new region. If
494 // new_region() didn't find a region on the free_list, this call will
495 // check whether there's anything available on the
496 // secondary_free_list and/or wait for more regions to appear on
497 // that list, if _free_regions_coming is set.
498 HeapRegion* new_region_try_secondary_free_list();
499
500 // Try to allocate a single non-humongous HeapRegion sufficient for
501 // an allocation of the given word_size. If do_expand is true,
502 // attempt to expand the heap if necessary to satisfy the allocation
503 // request.
504 HeapRegion* new_region(size_t word_size, bool do_expand);
505
506 // Attempt to satisfy a humongous allocation request of the given
507 // size by finding a contiguous set of free regions of num_regions
508 // length and remove them from the master free list. Return the
509 // index of the first region or G1_NULL_HRS_INDEX if the search
510 // was unsuccessful.
511 uint humongous_obj_allocate_find_first(uint num_regions,
512 size_t word_size);
513
514 // Initialize a contiguous set of free regions of length num_regions
515 // and starting at index first so that they appear as a single
516 // humongous region.
517 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
518 uint num_regions,
519 size_t word_size);
520
521 // Attempt to allocate a humongous object of the given size. Return
522 // NULL if unsuccessful.
523 HeapWord* humongous_obj_allocate(size_t word_size);
524
525 // The following two methods, allocate_new_tlab() and
526 // mem_allocate(), are the two main entry points from the runtime
527 // into the G1's allocation routines. They have the following
528 // assumptions:
529 //
530 // * They should both be called outside safepoints.
531 //
532 // * They should both be called without holding the Heap_lock.
533 //
534 // * All allocation requests for new TLABs should go to
535 // allocate_new_tlab().
536 //
537 // * All non-TLAB allocation requests should go to mem_allocate().
538 //
539 // * If either call cannot satisfy the allocation request using the
540 // current allocating region, they will try to get a new one. If
541 // this fails, they will attempt to do an evacuation pause and
542 // retry the allocation.
543 //
544 // * If all allocation attempts fail, even after trying to schedule
545 // an evacuation pause, allocate_new_tlab() will return NULL,
546 // whereas mem_allocate() will attempt a heap expansion and/or
547 // schedule a Full GC.
548 //
549 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
550 // should never be called with word_size being humongous. All
551 // humongous allocation requests should go to mem_allocate() which
552 // will satisfy them with a special path.
553
554 virtual HeapWord* allocate_new_tlab(size_t word_size);
555
556 virtual HeapWord* mem_allocate(size_t word_size,
557 bool* gc_overhead_limit_was_exceeded);
558
559 // The following three methods take a gc_count_before_ret
560 // parameter which is used to return the GC count if the method
561 // returns NULL. Given that we are required to read the GC count
562 // while holding the Heap_lock, and these paths will take the
563 // Heap_lock at some point, it's easier to get them to read the GC
564 // count while holding the Heap_lock before they return NULL instead
565 // of the caller (namely: mem_allocate()) having to also take the
566 // Heap_lock just to read the GC count.
567
568 // First-level mutator allocation attempt: try to allocate out of
569 // the mutator alloc region without taking the Heap_lock. This
570 // should only be used for non-humongous allocations.
571 inline HeapWord* attempt_allocation(size_t word_size,
572 unsigned int* gc_count_before_ret,
573 int* gclocker_retry_count_ret);
574
575 // Second-level mutator allocation attempt: take the Heap_lock and
576 // retry the allocation attempt, potentially scheduling a GC
577 // pause. This should only be used for non-humongous allocations.
578 HeapWord* attempt_allocation_slow(size_t word_size,
579 unsigned int* gc_count_before_ret,
580 int* gclocker_retry_count_ret);
581
582 // Takes the Heap_lock and attempts a humongous allocation. It can
583 // potentially schedule a GC pause.
584 HeapWord* attempt_allocation_humongous(size_t word_size,
585 unsigned int* gc_count_before_ret,
586 int* gclocker_retry_count_ret);
587
588 // Allocation attempt that should be called during safepoints (e.g.,
589 // at the end of a successful GC). expect_null_mutator_alloc_region
590 // specifies whether the mutator alloc region is expected to be NULL
591 // or not.
592 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
593 bool expect_null_mutator_alloc_region);
594
595 // It dirties the cards that cover the block so that so that the post
596 // write barrier never queues anything when updating objects on this
597 // block. It is assumed (and in fact we assert) that the block
598 // belongs to a young region.
599 inline void dirty_young_block(HeapWord* start, size_t word_size);
600
601 // Allocate blocks during garbage collection. Will ensure an
602 // allocation region, either by picking one or expanding the
603 // heap, and then allocate a block of the given size. The block
604 // may not be a humongous - it must fit into a single heap region.
605 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
606
607 // Ensure that no further allocations can happen in "r", bearing in mind
608 // that parallel threads might be attempting allocations.
609 void par_allocate_remaining_space(HeapRegion* r);
610
611 // Allocation attempt during GC for a survivor object / PLAB.
612 inline HeapWord* survivor_attempt_allocation(size_t word_size);
613
614 // Allocation attempt during GC for an old object / PLAB.
615 inline HeapWord* old_attempt_allocation(size_t word_size);
616
617 // These methods are the "callbacks" from the G1AllocRegion class.
618
619 // For mutator alloc regions.
620 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
621 void retire_mutator_alloc_region(HeapRegion* alloc_region,
622 size_t allocated_bytes);
623
624 // For GC alloc regions.
625 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
626 GCAllocPurpose ap);
627 void retire_gc_alloc_region(HeapRegion* alloc_region,
628 size_t allocated_bytes, GCAllocPurpose ap);
629
630 // - if explicit_gc is true, the GC is for a System.gc() or a heap
631 // inspection request and should collect the entire heap
632 // - if clear_all_soft_refs is true, all soft references should be
633 // cleared during the GC
634 // - if explicit_gc is false, word_size describes the allocation that
635 // the GC should attempt (at least) to satisfy
636 // - it returns false if it is unable to do the collection due to the
637 // GC locker being active, true otherwise
638 bool do_collection(bool explicit_gc,
639 bool clear_all_soft_refs,
640 size_t word_size);
641
642 // Callback from VM_G1CollectFull operation.
643 // Perform a full collection.
644 virtual void do_full_collection(bool clear_all_soft_refs);
645
646 // Resize the heap if necessary after a full collection. If this is
647 // after a collect-for allocation, "word_size" is the allocation size,
648 // and will be considered part of the used portion of the heap.
649 void resize_if_necessary_after_full_collection(size_t word_size);
650
651 // Callback from VM_G1CollectForAllocation operation.
652 // This function does everything necessary/possible to satisfy a
653 // failed allocation request (including collection, expansion, etc.)
654 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
655
656 // Attempting to expand the heap sufficiently
657 // to support an allocation of the given "word_size". If
658 // successful, perform the allocation and return the address of the
659 // allocated block, or else "NULL".
660 HeapWord* expand_and_allocate(size_t word_size);
661
662 // Process any reference objects discovered during
663 // an incremental evacuation pause.
664 void process_discovered_references(uint no_of_gc_workers);
665
666 // Enqueue any remaining discovered references
667 // after processing.
668 void enqueue_discovered_references(uint no_of_gc_workers);
669
670 public:
671
672 G1MonitoringSupport* g1mm() {
673 assert(_g1mm != NULL, "should have been initialized");
674 return _g1mm;
675 }
676
677 // Expand the garbage-first heap by at least the given size (in bytes!).
678 // Returns true if the heap was expanded by the requested amount;
679 // false otherwise.
680 // (Rounds up to a HeapRegion boundary.)
681 bool expand(size_t expand_bytes);
682
683 // Do anything common to GC's.
684 virtual void gc_prologue(bool full);
685 virtual void gc_epilogue(bool full);
686
687 // We register a region with the fast "in collection set" test. We
688 // simply set to true the array slot corresponding to this region.
689 void register_region_with_in_cset_fast_test(HeapRegion* r) {
690 assert(_in_cset_fast_test_base != NULL, "sanity");
691 assert(r->in_collection_set(), "invariant");
692 uint index = r->hrs_index();
693 assert(index < _in_cset_fast_test_length, "invariant");
694 assert(!_in_cset_fast_test_base[index], "invariant");
695 _in_cset_fast_test_base[index] = true;
696 }
697
698 // This is a fast test on whether a reference points into the
699 // collection set or not. It does not assume that the reference
700 // points into the heap; if it doesn't, it will return false.
701 bool in_cset_fast_test(oop obj) {
702 assert(_in_cset_fast_test != NULL, "sanity");
703 if (_g1_committed.contains((HeapWord*) obj)) {
704 // no need to subtract the bottom of the heap from obj,
705 // _in_cset_fast_test is biased
706 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
707 bool ret = _in_cset_fast_test[index];
708 // let's make sure the result is consistent with what the slower
709 // test returns
710 assert( ret || !obj_in_cs(obj), "sanity");
711 assert(!ret || obj_in_cs(obj), "sanity");
712 return ret;
713 } else {
714 return false;
715 }
716 }
717
718 void clear_cset_fast_test() {
719 assert(_in_cset_fast_test_base != NULL, "sanity");
720 memset(_in_cset_fast_test_base, false,
721 (size_t) _in_cset_fast_test_length * sizeof(bool));
722 }
723
724 // This is called at the start of either a concurrent cycle or a Full
725 // GC to update the number of old marking cycles started.
726 void increment_old_marking_cycles_started();
727
728 // This is called at the end of either a concurrent cycle or a Full
729 // GC to update the number of old marking cycles completed. Those two
730 // can happen in a nested fashion, i.e., we start a concurrent
731 // cycle, a Full GC happens half-way through it which ends first,
732 // and then the cycle notices that a Full GC happened and ends
733 // too. The concurrent parameter is a boolean to help us do a bit
734 // tighter consistency checking in the method. If concurrent is
735 // false, the caller is the inner caller in the nesting (i.e., the
736 // Full GC). If concurrent is true, the caller is the outer caller
737 // in this nesting (i.e., the concurrent cycle). Further nesting is
738 // not currently supported. The end of this call also notifies
739 // the FullGCCount_lock in case a Java thread is waiting for a full
740 // GC to happen (e.g., it called System.gc() with
741 // +ExplicitGCInvokesConcurrent).
742 void increment_old_marking_cycles_completed(bool concurrent);
743
744 unsigned int old_marking_cycles_completed() {
745 return _old_marking_cycles_completed;
746 }
747
748 void register_concurrent_cycle_start(jlong start_time);
749 void register_concurrent_cycle_end();
750 void trace_heap_after_concurrent_cycle();
751
752 G1YCType yc_type();
753
754 G1HRPrinter* hr_printer() { return &_hr_printer; }
755
756 protected:
757
758 // Shrink the garbage-first heap by at most the given size (in bytes!).
759 // (Rounds down to a HeapRegion boundary.)
760 virtual void shrink(size_t expand_bytes);
761 void shrink_helper(size_t expand_bytes);
762
763 #if TASKQUEUE_STATS
764 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
765 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
766 void reset_taskqueue_stats();
767 #endif // TASKQUEUE_STATS
768
769 // Schedule the VM operation that will do an evacuation pause to
770 // satisfy an allocation request of word_size. *succeeded will
771 // return whether the VM operation was successful (it did do an
772 // evacuation pause) or not (another thread beat us to it or the GC
773 // locker was active). Given that we should not be holding the
774 // Heap_lock when we enter this method, we will pass the
775 // gc_count_before (i.e., total_collections()) as a parameter since
776 // it has to be read while holding the Heap_lock. Currently, both
777 // methods that call do_collection_pause() release the Heap_lock
778 // before the call, so it's easy to read gc_count_before just before.
779 HeapWord* do_collection_pause(size_t word_size,
780 unsigned int gc_count_before,
781 bool* succeeded);
782
783 // The guts of the incremental collection pause, executed by the vm
784 // thread. It returns false if it is unable to do the collection due
785 // to the GC locker being active, true otherwise
786 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
787
788 // Actually do the work of evacuating the collection set.
789 void evacuate_collection_set(EvacuationInfo& evacuation_info);
790
791 // The g1 remembered set of the heap.
792 G1RemSet* _g1_rem_set;
793 // And it's mod ref barrier set, used to track updates for the above.
794 ModRefBarrierSet* _mr_bs;
795
796 // A set of cards that cover the objects for which the Rsets should be updated
797 // concurrently after the collection.
798 DirtyCardQueueSet _dirty_card_queue_set;
799
800 // The closure used to refine a single card.
801 RefineCardTableEntryClosure* _refine_cte_cl;
802
803 // A function to check the consistency of dirty card logs.
804 void check_ct_logs_at_safepoint();
805
806 // A DirtyCardQueueSet that is used to hold cards that contain
807 // references into the current collection set. This is used to
808 // update the remembered sets of the regions in the collection
809 // set in the event of an evacuation failure.
810 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
811
812 // After a collection pause, make the regions in the CS into free
813 // regions.
814 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
815
816 // Abandon the current collection set without recording policy
817 // statistics or updating free lists.
818 void abandon_collection_set(HeapRegion* cs_head);
819
820 // Applies "scan_non_heap_roots" to roots outside the heap,
821 // "scan_rs" to roots inside the heap (having done "set_region" to
822 // indicate the region in which the root resides),
823 // and does "scan_metadata" If "scan_rs" is
824 // NULL, then this step is skipped. The "worker_i"
825 // param is for use with parallel roots processing, and should be
826 // the "i" of the calling parallel worker thread's work(i) function.
827 // In the sequential case this param will be ignored.
828 void g1_process_strong_roots(bool is_scavenging,
829 ScanningOption so,
830 OopClosure* scan_non_heap_roots,
831 OopsInHeapRegionClosure* scan_rs,
832 G1KlassScanClosure* scan_klasses,
833 int worker_i);
834
835 // Apply "blk" to all the weak roots of the system. These include
836 // JNI weak roots, the code cache, system dictionary, symbol table,
837 // string table, and referents of reachable weak refs.
838 void g1_process_weak_roots(OopClosure* root_closure);
839
840 // Frees a non-humongous region by initializing its contents and
841 // adding it to the free list that's passed as a parameter (this is
842 // usually a local list which will be appended to the master free
843 // list later). The used bytes of freed regions are accumulated in
844 // pre_used. If par is true, the region's RSet will not be freed
845 // up. The assumption is that this will be done later.
846 void free_region(HeapRegion* hr,
847 size_t* pre_used,
848 FreeRegionList* free_list,
849 bool par);
850
851 // Frees a humongous region by collapsing it into individual regions
852 // and calling free_region() for each of them. The freed regions
853 // will be added to the free list that's passed as a parameter (this
854 // is usually a local list which will be appended to the master free
855 // list later). The used bytes of freed regions are accumulated in
856 // pre_used. If par is true, the region's RSet will not be freed
857 // up. The assumption is that this will be done later.
858 void free_humongous_region(HeapRegion* hr,
859 size_t* pre_used,
860 FreeRegionList* free_list,
861 HumongousRegionSet* humongous_proxy_set,
862 bool par);
863
864 // Notifies all the necessary spaces that the committed space has
865 // been updated (either expanded or shrunk). It should be called
866 // after _g1_storage is updated.
867 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
868
869 // The concurrent marker (and the thread it runs in.)
870 ConcurrentMark* _cm;
871 ConcurrentMarkThread* _cmThread;
872 bool _mark_in_progress;
873
874 // The concurrent refiner.
875 ConcurrentG1Refine* _cg1r;
876
877 // The parallel task queues
878 RefToScanQueueSet *_task_queues;
879
880 // True iff a evacuation has failed in the current collection.
881 bool _evacuation_failed;
882
883 EvacuationFailedInfo* _evacuation_failed_info_array;
884
885 // Failed evacuations cause some logical from-space objects to have
886 // forwarding pointers to themselves. Reset them.
887 void remove_self_forwarding_pointers();
888
889 // Together, these store an object with a preserved mark, and its mark value.
890 Stack<oop, mtGC> _objs_with_preserved_marks;
891 Stack<markOop, mtGC> _preserved_marks_of_objs;
892
893 // Preserve the mark of "obj", if necessary, in preparation for its mark
894 // word being overwritten with a self-forwarding-pointer.
895 void preserve_mark_if_necessary(oop obj, markOop m);
896
897 // The stack of evac-failure objects left to be scanned.
898 GrowableArray<oop>* _evac_failure_scan_stack;
899 // The closure to apply to evac-failure objects.
900
901 OopsInHeapRegionClosure* _evac_failure_closure;
902 // Set the field above.
903 void
904 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
905 _evac_failure_closure = evac_failure_closure;
906 }
907
908 // Push "obj" on the scan stack.
909 void push_on_evac_failure_scan_stack(oop obj);
910 // Process scan stack entries until the stack is empty.
911 void drain_evac_failure_scan_stack();
912 // True iff an invocation of "drain_scan_stack" is in progress; to
913 // prevent unnecessary recursion.
914 bool _drain_in_progress;
915
916 // Do any necessary initialization for evacuation-failure handling.
917 // "cl" is the closure that will be used to process evac-failure
918 // objects.
919 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
920 // Do any necessary cleanup for evacuation-failure handling data
921 // structures.
922 void finalize_for_evac_failure();
923
924 // An attempt to evacuate "obj" has failed; take necessary steps.
925 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
926 void handle_evacuation_failure_common(oop obj, markOop m);
927
928 #ifndef PRODUCT
929 // Support for forcing evacuation failures. Analogous to
930 // PromotionFailureALot for the other collectors.
931
932 // Records whether G1EvacuationFailureALot should be in effect
933 // for the current GC
934 bool _evacuation_failure_alot_for_current_gc;
935
936 // Used to record the GC number for interval checking when
937 // determining whether G1EvaucationFailureALot is in effect
938 // for the current GC.
939 size_t _evacuation_failure_alot_gc_number;
940
941 // Count of the number of evacuations between failures.
942 volatile size_t _evacuation_failure_alot_count;
943
944 // Set whether G1EvacuationFailureALot should be in effect
945 // for the current GC (based upon the type of GC and which
946 // command line flags are set);
947 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
948 bool during_initial_mark,
949 bool during_marking);
950
951 inline void set_evacuation_failure_alot_for_current_gc();
952
953 // Return true if it's time to cause an evacuation failure.
954 inline bool evacuation_should_fail();
955
956 // Reset the G1EvacuationFailureALot counters. Should be called at
957 // the end of an evacuation pause in which an evacuation failure occurred.
958 inline void reset_evacuation_should_fail();
959 #endif // !PRODUCT
960
961 // ("Weak") Reference processing support.
962 //
963 // G1 has 2 instances of the reference processor class. One
964 // (_ref_processor_cm) handles reference object discovery
965 // and subsequent processing during concurrent marking cycles.
966 //
967 // The other (_ref_processor_stw) handles reference object
968 // discovery and processing during full GCs and incremental
969 // evacuation pauses.
970 //
971 // During an incremental pause, reference discovery will be
972 // temporarily disabled for _ref_processor_cm and will be
973 // enabled for _ref_processor_stw. At the end of the evacuation
974 // pause references discovered by _ref_processor_stw will be
975 // processed and discovery will be disabled. The previous
976 // setting for reference object discovery for _ref_processor_cm
977 // will be re-instated.
978 //
979 // At the start of marking:
980 // * Discovery by the CM ref processor is verified to be inactive
981 // and it's discovered lists are empty.
982 // * Discovery by the CM ref processor is then enabled.
983 //
984 // At the end of marking:
985 // * Any references on the CM ref processor's discovered
986 // lists are processed (possibly MT).
987 //
988 // At the start of full GC we:
989 // * Disable discovery by the CM ref processor and
990 // empty CM ref processor's discovered lists
991 // (without processing any entries).
992 // * Verify that the STW ref processor is inactive and it's
993 // discovered lists are empty.
994 // * Temporarily set STW ref processor discovery as single threaded.
995 // * Temporarily clear the STW ref processor's _is_alive_non_header
996 // field.
997 // * Finally enable discovery by the STW ref processor.
998 //
999 // The STW ref processor is used to record any discovered
1000 // references during the full GC.
1001 //
1002 // At the end of a full GC we:
1003 // * Enqueue any reference objects discovered by the STW ref processor
1004 // that have non-live referents. This has the side-effect of
1005 // making the STW ref processor inactive by disabling discovery.
1006 // * Verify that the CM ref processor is still inactive
1007 // and no references have been placed on it's discovered
1008 // lists (also checked as a precondition during initial marking).
1009
1010 // The (stw) reference processor...
1011 ReferenceProcessor* _ref_processor_stw;
1012
1013 STWGCTimer* _gc_timer_stw;
1014 ConcurrentGCTimer* _gc_timer_cm;
1015
1016 G1OldTracer* _gc_tracer_cm;
1017 G1NewTracer* _gc_tracer_stw;
1018
1019 // During reference object discovery, the _is_alive_non_header
1020 // closure (if non-null) is applied to the referent object to
1021 // determine whether the referent is live. If so then the
1022 // reference object does not need to be 'discovered' and can
1023 // be treated as a regular oop. This has the benefit of reducing
1024 // the number of 'discovered' reference objects that need to
1025 // be processed.
1026 //
1027 // Instance of the is_alive closure for embedding into the
1028 // STW reference processor as the _is_alive_non_header field.
1029 // Supplying a value for the _is_alive_non_header field is
1030 // optional but doing so prevents unnecessary additions to
1031 // the discovered lists during reference discovery.
1032 G1STWIsAliveClosure _is_alive_closure_stw;
1033
1034 // The (concurrent marking) reference processor...
1035 ReferenceProcessor* _ref_processor_cm;
1036
1037 // Instance of the concurrent mark is_alive closure for embedding
1038 // into the Concurrent Marking reference processor as the
1039 // _is_alive_non_header field. Supplying a value for the
1040 // _is_alive_non_header field is optional but doing so prevents
1041 // unnecessary additions to the discovered lists during reference
1042 // discovery.
1043 G1CMIsAliveClosure _is_alive_closure_cm;
1044
1045 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1046 HeapRegion** _worker_cset_start_region;
1047
1048 // Time stamp to validate the regions recorded in the cache
1049 // used by G1CollectedHeap::start_cset_region_for_worker().
1050 // The heap region entry for a given worker is valid iff
1051 // the associated time stamp value matches the current value
1052 // of G1CollectedHeap::_gc_time_stamp.
1053 unsigned int* _worker_cset_start_region_time_stamp;
1054
1055 enum G1H_process_strong_roots_tasks {
1056 G1H_PS_filter_satb_buffers,
1057 G1H_PS_refProcessor_oops_do,
1058 // Leave this one last.
1059 G1H_PS_NumElements
1060 };
1061
1062 SubTasksDone* _process_strong_tasks;
1063
1064 volatile bool _free_regions_coming;
1065
1066 public:
1067
1068 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1069
1070 void set_refine_cte_cl_concurrency(bool concurrent);
1071
1072 RefToScanQueue *task_queue(int i) const;
1073
1074 // A set of cards where updates happened during the GC
1075 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1076
1077 // A DirtyCardQueueSet that is used to hold cards that contain
1078 // references into the current collection set. This is used to
1079 // update the remembered sets of the regions in the collection
1080 // set in the event of an evacuation failure.
1081 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1082 { return _into_cset_dirty_card_queue_set; }
1083
1084 // Create a G1CollectedHeap with the specified policy.
1085 // Must call the initialize method afterwards.
1086 // May not return if something goes wrong.
1087 G1CollectedHeap(G1CollectorPolicy* policy);
1088
1089 // Initialize the G1CollectedHeap to have the initial and
1090 // maximum sizes and remembered and barrier sets
1091 // specified by the policy object.
1092 jint initialize();
1093
1094 // return the (conservative) maximum heap alignment for any G1 heap
1095 static size_t conservative_max_heap_alignment();
1096
1097 // Initialize weak reference processing.
1098 virtual void ref_processing_init();
1099
1100 void set_par_threads(uint t) {
1101 SharedHeap::set_par_threads(t);
1102 // Done in SharedHeap but oddly there are
1103 // two _process_strong_tasks's in a G1CollectedHeap
1104 // so do it here too.
1105 _process_strong_tasks->set_n_threads(t);
1106 }
1107
1108 // Set _n_par_threads according to a policy TBD.
1109 void set_par_threads();
1110
1111 void set_n_termination(int t) {
1112 _process_strong_tasks->set_n_threads(t);
1113 }
1114
1115 virtual CollectedHeap::Name kind() const {
1116 return CollectedHeap::G1CollectedHeap;
1117 }
1118
1119 // The current policy object for the collector.
1120 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1121
1122 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1123
1124 // Adaptive size policy. No such thing for g1.
1125 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1126
1127 // The rem set and barrier set.
1128 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1129 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1130
1131 unsigned get_gc_time_stamp() {
1132 return _gc_time_stamp;
1133 }
1134
1135 void reset_gc_time_stamp() {
1136 _gc_time_stamp = 0;
1137 OrderAccess::fence();
1138 // Clear the cached CSet starting regions and time stamps.
1139 // Their validity is dependent on the GC timestamp.
1140 clear_cset_start_regions();
1141 }
1142
1143 void check_gc_time_stamps() PRODUCT_RETURN;
1144
1145 void increment_gc_time_stamp() {
1146 ++_gc_time_stamp;
1147 OrderAccess::fence();
1148 }
1149
1150 // Reset the given region's GC timestamp. If it's starts humongous,
1151 // also reset the GC timestamp of its corresponding
1152 // continues humongous regions too.
1153 void reset_gc_time_stamps(HeapRegion* hr);
1154
1155 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1156 DirtyCardQueue* into_cset_dcq,
1157 bool concurrent, int worker_i);
1158
1159 // The shared block offset table array.
1160 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1161
1162 // Reference Processing accessors
1163
1164 // The STW reference processor....
1165 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1166
1167 // The Concurrent Marking reference processor...
1168 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1169
1170 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1171 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1172
1173 virtual size_t capacity() const;
1174 virtual size_t used() const;
1175 // This should be called when we're not holding the heap lock. The
1176 // result might be a bit inaccurate.
1177 size_t used_unlocked() const;
1178 size_t recalculate_used() const;
1179
1180 // These virtual functions do the actual allocation.
1181 // Some heaps may offer a contiguous region for shared non-blocking
1182 // allocation, via inlined code (by exporting the address of the top and
1183 // end fields defining the extent of the contiguous allocation region.)
1184 // But G1CollectedHeap doesn't yet support this.
1185
1186 // Return an estimate of the maximum allocation that could be performed
1187 // without triggering any collection or expansion activity. In a
1188 // generational collector, for example, this is probably the largest
1189 // allocation that could be supported (without expansion) in the youngest
1190 // generation. It is "unsafe" because no locks are taken; the result
1191 // should be treated as an approximation, not a guarantee, for use in
1192 // heuristic resizing decisions.
1193 virtual size_t unsafe_max_alloc();
1194
1195 virtual bool is_maximal_no_gc() const {
1196 return _g1_storage.uncommitted_size() == 0;
1197 }
1198
1199 // The total number of regions in the heap.
1200 uint n_regions() { return _hrs.length(); }
1201
1202 // The max number of regions in the heap.
1203 uint max_regions() { return _hrs.max_length(); }
1204
1205 // The number of regions that are completely free.
1206 uint free_regions() { return _free_list.length(); }
1207
1208 // The number of regions that are not completely free.
1209 uint used_regions() { return n_regions() - free_regions(); }
1210
1211 // The number of regions available for "regular" expansion.
1212 uint expansion_regions() { return _expansion_regions; }
1213
1214 // Factory method for HeapRegion instances. It will return NULL if
1215 // the allocation fails.
1216 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1217
1218 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1219 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1220 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1221 void verify_dirty_young_regions() PRODUCT_RETURN;
1222
1223 // verify_region_sets() performs verification over the region
1224 // lists. It will be compiled in the product code to be used when
1225 // necessary (i.e., during heap verification).
1226 void verify_region_sets();
1227
1228 // verify_region_sets_optional() is planted in the code for
1229 // list verification in non-product builds (and it can be enabled in
1230 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1231 #if HEAP_REGION_SET_FORCE_VERIFY
1232 void verify_region_sets_optional() {
1233 verify_region_sets();
1234 }
1235 #else // HEAP_REGION_SET_FORCE_VERIFY
1236 void verify_region_sets_optional() { }
1237 #endif // HEAP_REGION_SET_FORCE_VERIFY
1238
1239 #ifdef ASSERT
1240 bool is_on_master_free_list(HeapRegion* hr) {
1241 return hr->containing_set() == &_free_list;
1242 }
1243
1244 bool is_in_humongous_set(HeapRegion* hr) {
1245 return hr->containing_set() == &_humongous_set;
1246 }
1247 #endif // ASSERT
1248
1249 // Wrapper for the region list operations that can be called from
1250 // methods outside this class.
1251
1252 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1253 _secondary_free_list.add_as_tail(list);
1254 }
1255
1256 void append_secondary_free_list() {
1257 _free_list.add_as_head(&_secondary_free_list);
1258 }
1259
1260 void append_secondary_free_list_if_not_empty_with_lock() {
1261 // If the secondary free list looks empty there's no reason to
1262 // take the lock and then try to append it.
1263 if (!_secondary_free_list.is_empty()) {
1264 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1265 append_secondary_free_list();
1266 }
1267 }
1268
1269 void old_set_remove(HeapRegion* hr) {
1270 _old_set.remove(hr);
1271 }
1272
1273 size_t non_young_capacity_bytes() {
1274 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1275 }
1276
1277 void set_free_regions_coming();
1278 void reset_free_regions_coming();
1279 bool free_regions_coming() { return _free_regions_coming; }
1280 void wait_while_free_regions_coming();
1281
1282 // Determine whether the given region is one that we are using as an
1283 // old GC alloc region.
1284 bool is_old_gc_alloc_region(HeapRegion* hr) {
1285 return hr == _retained_old_gc_alloc_region;
1286 }
1287
1288 // Perform a collection of the heap; intended for use in implementing
1289 // "System.gc". This probably implies as full a collection as the
1290 // "CollectedHeap" supports.
1291 virtual void collect(GCCause::Cause cause);
1292
1293 // The same as above but assume that the caller holds the Heap_lock.
1294 void collect_locked(GCCause::Cause cause);
1295
1296 // True iff an evacuation has failed in the most-recent collection.
1297 bool evacuation_failed() { return _evacuation_failed; }
1298
1299 // It will free a region if it has allocated objects in it that are
1300 // all dead. It calls either free_region() or
1301 // free_humongous_region() depending on the type of the region that
1302 // is passed to it.
1303 void free_region_if_empty(HeapRegion* hr,
1304 size_t* pre_used,
1305 FreeRegionList* free_list,
1306 OldRegionSet* old_proxy_set,
1307 HumongousRegionSet* humongous_proxy_set,
1308 HRRSCleanupTask* hrrs_cleanup_task,
1309 bool par);
1310
1311 // It appends the free list to the master free list and updates the
1312 // master humongous list according to the contents of the proxy
1313 // list. It also adjusts the total used bytes according to pre_used
1314 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1315 void update_sets_after_freeing_regions(size_t pre_used,
1316 FreeRegionList* free_list,
1317 OldRegionSet* old_proxy_set,
1318 HumongousRegionSet* humongous_proxy_set,
1319 bool par);
1320
1321 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1322 virtual bool is_in(const void* p) const;
1323
1324 // Return "TRUE" iff the given object address is within the collection
1325 // set.
1326 inline bool obj_in_cs(oop obj);
1327
1328 // Return "TRUE" iff the given object address is in the reserved
1329 // region of g1.
1330 bool is_in_g1_reserved(const void* p) const {
1331 return _g1_reserved.contains(p);
1332 }
1333
1334 // Returns a MemRegion that corresponds to the space that has been
1335 // reserved for the heap
1336 MemRegion g1_reserved() {
1337 return _g1_reserved;
1338 }
1339
1340 // Returns a MemRegion that corresponds to the space that has been
1341 // committed in the heap
1342 MemRegion g1_committed() {
1343 return _g1_committed;
1344 }
1345
1346 virtual bool is_in_closed_subset(const void* p) const;
1347
1348 // This resets the card table to all zeros. It is used after
1349 // a collection pause which used the card table to claim cards.
1350 void cleanUpCardTable();
1351
1352 // Iteration functions.
1353
1354 // Iterate over all the ref-containing fields of all objects, calling
1355 // "cl.do_oop" on each.
1356 virtual void oop_iterate(ExtendedOopClosure* cl);
1357
1358 // Same as above, restricted to a memory region.
1359 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1360
1361 // Iterate over all objects, calling "cl.do_object" on each.
1362 virtual void object_iterate(ObjectClosure* cl);
1363
1364 virtual void safe_object_iterate(ObjectClosure* cl) {
1365 object_iterate(cl);
1366 }
1367
1368 // Iterate over all spaces in use in the heap, in ascending address order.
1369 virtual void space_iterate(SpaceClosure* cl);
1370
1371 // Iterate over heap regions, in address order, terminating the
1372 // iteration early if the "doHeapRegion" method returns "true".
1373 void heap_region_iterate(HeapRegionClosure* blk) const;
1374
1375 // Return the region with the given index. It assumes the index is valid.
1376 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1377
1378 // Divide the heap region sequence into "chunks" of some size (the number
1379 // of regions divided by the number of parallel threads times some
1380 // overpartition factor, currently 4). Assumes that this will be called
1381 // in parallel by ParallelGCThreads worker threads with discinct worker
1382 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1383 // calls will use the same "claim_value", and that that claim value is
1384 // different from the claim_value of any heap region before the start of
1385 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1386 // attempting to claim the first region in each chunk, and, if
1387 // successful, applying the closure to each region in the chunk (and
1388 // setting the claim value of the second and subsequent regions of the
1389 // chunk.) For now requires that "doHeapRegion" always returns "false",
1390 // i.e., that a closure never attempt to abort a traversal.
1391 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1392 uint worker,
1393 uint no_of_par_workers,
1394 jint claim_value);
1395
1396 // It resets all the region claim values to the default.
1397 void reset_heap_region_claim_values();
1398
1399 // Resets the claim values of regions in the current
1400 // collection set to the default.
1401 void reset_cset_heap_region_claim_values();
1402
1403 #ifdef ASSERT
1404 bool check_heap_region_claim_values(jint claim_value);
1405
1406 // Same as the routine above but only checks regions in the
1407 // current collection set.
1408 bool check_cset_heap_region_claim_values(jint claim_value);
1409 #endif // ASSERT
1410
1411 // Clear the cached cset start regions and (more importantly)
1412 // the time stamps. Called when we reset the GC time stamp.
1413 void clear_cset_start_regions();
1414
1415 // Given the id of a worker, obtain or calculate a suitable
1416 // starting region for iterating over the current collection set.
1417 HeapRegion* start_cset_region_for_worker(int worker_i);
1418
1419 // This is a convenience method that is used by the
1420 // HeapRegionIterator classes to calculate the starting region for
1421 // each worker so that they do not all start from the same region.
1422 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1423
1424 // Iterate over the regions (if any) in the current collection set.
1425 void collection_set_iterate(HeapRegionClosure* blk);
1426
1427 // As above but starting from region r
1428 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1429
1430 // Returns the first (lowest address) compactible space in the heap.
1431 virtual CompactibleSpace* first_compactible_space();
1432
1433 // A CollectedHeap will contain some number of spaces. This finds the
1434 // space containing a given address, or else returns NULL.
1435 virtual Space* space_containing(const void* addr) const;
1436
1437 // A G1CollectedHeap will contain some number of heap regions. This
1438 // finds the region containing a given address, or else returns NULL.
1439 template <class T>
1440 inline HeapRegion* heap_region_containing(const T addr) const;
1441
1442 // Like the above, but requires "addr" to be in the heap (to avoid a
1443 // null-check), and unlike the above, may return an continuing humongous
1444 // region.
1445 template <class T>
1446 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1447
1448 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1449 // each address in the (reserved) heap is a member of exactly
1450 // one block. The defining characteristic of a block is that it is
1451 // possible to find its size, and thus to progress forward to the next
1452 // block. (Blocks may be of different sizes.) Thus, blocks may
1453 // represent Java objects, or they might be free blocks in a
1454 // free-list-based heap (or subheap), as long as the two kinds are
1455 // distinguishable and the size of each is determinable.
1456
1457 // Returns the address of the start of the "block" that contains the
1458 // address "addr". We say "blocks" instead of "object" since some heaps
1459 // may not pack objects densely; a chunk may either be an object or a
1460 // non-object.
1461 virtual HeapWord* block_start(const void* addr) const;
1462
1463 // Requires "addr" to be the start of a chunk, and returns its size.
1464 // "addr + size" is required to be the start of a new chunk, or the end
1465 // of the active area of the heap.
1466 virtual size_t block_size(const HeapWord* addr) const;
1467
1468 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1469 // the block is an object.
1470 virtual bool block_is_obj(const HeapWord* addr) const;
1471
1472 // Does this heap support heap inspection? (+PrintClassHistogram)
1473 virtual bool supports_heap_inspection() const { return true; }
1474
1475 // Section on thread-local allocation buffers (TLABs)
1476 // See CollectedHeap for semantics.
1477
1478 virtual bool supports_tlab_allocation() const;
1479 virtual size_t tlab_capacity(Thread* thr) const;
1480 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1481
1482 // Can a compiler initialize a new object without store barriers?
1483 // This permission only extends from the creation of a new object
1484 // via a TLAB up to the first subsequent safepoint. If such permission
1485 // is granted for this heap type, the compiler promises to call
1486 // defer_store_barrier() below on any slow path allocation of
1487 // a new object for which such initializing store barriers will
1488 // have been elided. G1, like CMS, allows this, but should be
1489 // ready to provide a compensating write barrier as necessary
1490 // if that storage came out of a non-young region. The efficiency
1491 // of this implementation depends crucially on being able to
1492 // answer very efficiently in constant time whether a piece of
1493 // storage in the heap comes from a young region or not.
1494 // See ReduceInitialCardMarks.
1495 virtual bool can_elide_tlab_store_barriers() const {
1496 return true;
1497 }
1498
1499 virtual bool card_mark_must_follow_store() const {
1500 return true;
1501 }
1502
1503 bool is_in_young(const oop obj) {
1504 HeapRegion* hr = heap_region_containing(obj);
1505 return hr != NULL && hr->is_young();
1506 }
1507
1508 #ifdef ASSERT
1509 virtual bool is_in_partial_collection(const void* p);
1510 #endif
1511
1512 virtual bool is_scavengable(const void* addr);
1513
1514 // We don't need barriers for initializing stores to objects
1515 // in the young gen: for the SATB pre-barrier, there is no
1516 // pre-value that needs to be remembered; for the remembered-set
1517 // update logging post-barrier, we don't maintain remembered set
1518 // information for young gen objects.
1519 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1520 return is_in_young(new_obj);
1521 }
1522
1523 // Returns "true" iff the given word_size is "very large".
1524 static bool isHumongous(size_t word_size) {
1525 // Note this has to be strictly greater-than as the TLABs
1526 // are capped at the humongous thresold and we want to
1527 // ensure that we don't try to allocate a TLAB as
1528 // humongous and that we don't allocate a humongous
1529 // object in a TLAB.
1530 return word_size > _humongous_object_threshold_in_words;
1531 }
1532
1533 // Update mod union table with the set of dirty cards.
1534 void updateModUnion();
1535
1536 // Set the mod union bits corresponding to the given memRegion. Note
1537 // that this is always a safe operation, since it doesn't clear any
1538 // bits.
1539 void markModUnionRange(MemRegion mr);
1540
1541 // Records the fact that a marking phase is no longer in progress.
1542 void set_marking_complete() {
1543 _mark_in_progress = false;
1544 }
1545 void set_marking_started() {
1546 _mark_in_progress = true;
1547 }
1548 bool mark_in_progress() {
1549 return _mark_in_progress;
1550 }
1551
1552 // Print the maximum heap capacity.
1553 virtual size_t max_capacity() const;
1554
1555 virtual jlong millis_since_last_gc();
1556
1557
1558 // Convenience function to be used in situations where the heap type can be
1559 // asserted to be this type.
1560 static G1CollectedHeap* heap();
1561
1562 void set_region_short_lived_locked(HeapRegion* hr);
1563 // add appropriate methods for any other surv rate groups
1564
1565 YoungList* young_list() { return _young_list; }
1566
1567 // debugging
1568 bool check_young_list_well_formed() {
1569 return _young_list->check_list_well_formed();
1570 }
1571
1572 bool check_young_list_empty(bool check_heap,
1573 bool check_sample = true);
1574
1575 // *** Stuff related to concurrent marking. It's not clear to me that so
1576 // many of these need to be public.
1577
1578 // The functions below are helper functions that a subclass of
1579 // "CollectedHeap" can use in the implementation of its virtual
1580 // functions.
1581 // This performs a concurrent marking of the live objects in a
1582 // bitmap off to the side.
1583 void doConcurrentMark();
1584
1585 bool isMarkedPrev(oop obj) const;
1586 bool isMarkedNext(oop obj) const;
1587
1588 // Determine if an object is dead, given the object and also
1589 // the region to which the object belongs. An object is dead
1590 // iff a) it was not allocated since the last mark and b) it
1591 // is not marked.
1592
1593 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1594 return
1595 !hr->obj_allocated_since_prev_marking(obj) &&
1596 !isMarkedPrev(obj);
1597 }
1598
1599 // This function returns true when an object has been
1600 // around since the previous marking and hasn't yet
1601 // been marked during this marking.
1602
1603 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1604 return
1605 !hr->obj_allocated_since_next_marking(obj) &&
1606 !isMarkedNext(obj);
1607 }
1608
1609 // Determine if an object is dead, given only the object itself.
1610 // This will find the region to which the object belongs and
1611 // then call the region version of the same function.
1612
1613 // Added if it is NULL it isn't dead.
1614
1615 bool is_obj_dead(const oop obj) const {
1616 const HeapRegion* hr = heap_region_containing(obj);
1617 if (hr == NULL) {
1618 if (obj == NULL) return false;
1619 else return true;
1620 }
1621 else return is_obj_dead(obj, hr);
1622 }
1623
1624 bool is_obj_ill(const oop obj) const {
1625 const HeapRegion* hr = heap_region_containing(obj);
1626 if (hr == NULL) {
1627 if (obj == NULL) return false;
1628 else return true;
1629 }
1630 else return is_obj_ill(obj, hr);
1631 }
1632
1633 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1634 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1635 bool is_marked(oop obj, VerifyOption vo);
1636 const char* top_at_mark_start_str(VerifyOption vo);
1637
1638 ConcurrentMark* concurrent_mark() const { return _cm; }
1639
1640 // Refinement
1641
1642 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1643
1644 // The dirty cards region list is used to record a subset of regions
1645 // whose cards need clearing. The list if populated during the
1646 // remembered set scanning and drained during the card table
1647 // cleanup. Although the methods are reentrant, population/draining
1648 // phases must not overlap. For synchronization purposes the last
1649 // element on the list points to itself.
1650 HeapRegion* _dirty_cards_region_list;
1651 void push_dirty_cards_region(HeapRegion* hr);
1652 HeapRegion* pop_dirty_cards_region();
1653
1654 // Optimized nmethod scanning support routines
1655
1656 // Register the given nmethod with the G1 heap
1657 virtual void register_nmethod(nmethod* nm);
1658
1659 // Unregister the given nmethod from the G1 heap
1660 virtual void unregister_nmethod(nmethod* nm);
1661
1662 // Migrate the nmethods in the code root lists of the regions
1663 // in the collection set to regions in to-space. In the event
1664 // of an evacuation failure, nmethods that reference objects
1665 // that were not successfullly evacuated are not migrated.
1666 void migrate_strong_code_roots();
1667
1668 // During an initial mark pause, mark all the code roots that
1669 // point into regions *not* in the collection set.
1670 void mark_strong_code_roots(uint worker_id);
1671
1672 // Rebuild the stong code root lists for each region
1673 // after a full GC
1674 void rebuild_strong_code_roots();
1675
1676 // Verification
1677
1678 // The following is just to alert the verification code
1679 // that a full collection has occurred and that the
1680 // remembered sets are no longer up to date.
1681 bool _full_collection;
1682 void set_full_collection() { _full_collection = true;}
1683 void clear_full_collection() {_full_collection = false;}
1684 bool full_collection() {return _full_collection;}
1685
1686 // Perform any cleanup actions necessary before allowing a verification.
1687 virtual void prepare_for_verify();
1688
1689 // Perform verification.
1690
1691 // vo == UsePrevMarking -> use "prev" marking information,
1692 // vo == UseNextMarking -> use "next" marking information
1693 // vo == UseMarkWord -> use the mark word in the object header
1694 //
1695 // NOTE: Only the "prev" marking information is guaranteed to be
1696 // consistent most of the time, so most calls to this should use
1697 // vo == UsePrevMarking.
1698 // Currently, there is only one case where this is called with
1699 // vo == UseNextMarking, which is to verify the "next" marking
1700 // information at the end of remark.
1701 // Currently there is only one place where this is called with
1702 // vo == UseMarkWord, which is to verify the marking during a
1703 // full GC.
1704 void verify(bool silent, VerifyOption vo);
1705
1706 // Override; it uses the "prev" marking information
1707 virtual void verify(bool silent);
1708
1709 // The methods below are here for convenience and dispatch the
1710 // appropriate method depending on value of the given VerifyOption
1711 // parameter. The values for that parameter, and their meanings,
1712 // are the same as those above.
1713
1714 bool is_obj_dead_cond(const oop obj,
1715 const HeapRegion* hr,
1716 const VerifyOption vo) const {
1717 switch (vo) {
1718 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1719 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1720 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1721 default: ShouldNotReachHere();
1722 }
1723 return false; // keep some compilers happy
1724 }
1725
1726 bool is_obj_dead_cond(const oop obj,
1727 const VerifyOption vo) const {
1728 switch (vo) {
1729 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1730 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1731 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1732 default: ShouldNotReachHere();
1733 }
1734 return false; // keep some compilers happy
1735 }
1736
1737 // Printing
1738
1739 virtual void print_on(outputStream* st) const;
1740 virtual void print_extended_on(outputStream* st) const;
1741 virtual void print_on_error(outputStream* st) const;
1742
1743 virtual void print_gc_threads_on(outputStream* st) const;
1744 virtual void gc_threads_do(ThreadClosure* tc) const;
1745
1746 // Override
1747 void print_tracing_info() const;
1748
1749 // The following two methods are helpful for debugging RSet issues.
1750 void print_cset_rsets() PRODUCT_RETURN;
1751 void print_all_rsets() PRODUCT_RETURN;
1752
1753 public:
1754 void stop_conc_gc_threads();
1755
1756 size_t pending_card_num();
1757 size_t cards_scanned();
1758
1759 protected:
1760 size_t _max_heap_capacity;
1761 };
1762
1763 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1764 private:
1765 bool _retired;
1766
1767 public:
1768 G1ParGCAllocBuffer(size_t gclab_word_size);
1769
1770 void set_buf(HeapWord* buf) {
1771 ParGCAllocBuffer::set_buf(buf);
1772 _retired = false;
1773 }
1774
1775 void retire(bool end_of_gc, bool retain) {
1776 if (_retired)
1777 return;
1778 ParGCAllocBuffer::retire(end_of_gc, retain);
1779 _retired = true;
1780 }
1781
1782 bool is_retired() {
1783 return _retired;
1784 }
1785 };
1786
1787 class G1ParGCAllocBufferContainer {
1788 protected:
1789 static int const _priority_max = 2;
1790 G1ParGCAllocBuffer* _priority_buffer[_priority_max];
1791
1792 public:
1793 G1ParGCAllocBufferContainer(size_t gclab_word_size) {
1794 for (int pr = 0; pr < _priority_max; ++pr) {
1795 _priority_buffer[pr] = new G1ParGCAllocBuffer(gclab_word_size);
1796 }
1797 }
1798
1799 ~G1ParGCAllocBufferContainer() {
1800 for (int pr = 0; pr < _priority_max; ++pr) {
1801 assert(_priority_buffer[pr]->is_retired(), "alloc buffers should all retire at this point.");
1802 delete _priority_buffer[pr];
1803 }
1804 }
1805
1806 HeapWord* allocate(size_t word_sz) {
1807 HeapWord* obj;
1808 for (int pr = 0; pr < _priority_max; ++pr) {
1809 obj = _priority_buffer[pr]->allocate(word_sz);
1810 if (obj != NULL) return obj;
1811 }
1812 return obj;
1813 }
1814
1815 bool contains(void* addr) {
1816 for (int pr = 0; pr < _priority_max; ++pr) {
1817 if (_priority_buffer[pr]->contains(addr)) return true;
1818 }
1819 return false;
1820 }
1821
1822 void undo_allocation(HeapWord* obj, size_t word_sz) {
1823 bool finish_undo;
1824 for (int pr = 0; pr < _priority_max; ++pr) {
1825 if (_priority_buffer[pr]->contains(obj)) {
1826 _priority_buffer[pr]->undo_allocation(obj, word_sz);
1827 finish_undo = true;
1828 }
1829 }
1830 if (!finish_undo) ShouldNotReachHere();
1831 }
1832
1833 size_t words_remaining() {
1834 size_t result = 0;
1835 for (int pr = 0; pr < _priority_max; ++pr) {
1836 result += _priority_buffer[pr]->words_remaining();
1837 }
1838 return result;
1839 }
1840
1841 size_t words_remaining_in_retired_buffer() {
1842 G1ParGCAllocBuffer* retired = _priority_buffer[0];
1843 return retired->words_remaining();
1844 }
1845
1846 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) {
1847 for (int pr = 0; pr < _priority_max; ++pr) {
1848 _priority_buffer[pr]->flush_stats_and_retire(stats, end_of_gc, retain);
1849 }
1850 }
1851
1852 void update(bool end_of_gc, bool retain, HeapWord* buf, size_t word_sz) {
1853 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0];
1854 retired_and_set->retire(end_of_gc, retain);
1855 retired_and_set->set_buf(buf);
1856 retired_and_set->set_word_size(word_sz);
1857 adjust_priority_order();
1858 }
1859
1860 private:
1861 void adjust_priority_order() {
1862 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0];
1863
1864 int last = _priority_max - 1;
1865 for (int pr = 0; pr < last; ++pr) {
1866 _priority_buffer[pr] = _priority_buffer[pr + 1];
1867 }
1868 _priority_buffer[last] = retired_and_set;
1869 }
1870 };
1871
1872 class G1ParScanThreadState : public StackObj {
1873 protected:
1874 G1CollectedHeap* _g1h;
1875 RefToScanQueue* _refs;
1876 DirtyCardQueue _dcq;
1877 CardTableModRefBS* _ct_bs;
1878 G1RemSet* _g1_rem;
1879
1880 G1ParGCAllocBufferContainer _surviving_alloc_buffer;
1881 G1ParGCAllocBufferContainer _tenured_alloc_buffer;
1882 G1ParGCAllocBufferContainer* _alloc_buffers[GCAllocPurposeCount];
1883 ageTable _age_table;
1884
1885 size_t _alloc_buffer_waste;
1886 size_t _undo_waste;
1887
1888 OopsInHeapRegionClosure* _evac_failure_cl;
1889 G1ParScanHeapEvacClosure* _evac_cl;
1890 G1ParScanPartialArrayClosure* _partial_scan_cl;
1891
1892 int _hash_seed;
1893 uint _queue_num;
1894
1895 size_t _term_attempts;
1896
1897 double _start;
1898 double _start_strong_roots;
1899 double _strong_roots_time;
1900 double _start_term;
1901 double _term_time;
1902
1903 // Map from young-age-index (0 == not young, 1 is youngest) to
1904 // surviving words. base is what we get back from the malloc call
1905 size_t* _surviving_young_words_base;
1906 // this points into the array, as we use the first few entries for padding
1907 size_t* _surviving_young_words;
1908
1909 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1910
1911 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1912
1913 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1914
1915 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1916 CardTableModRefBS* ctbs() { return _ct_bs; }
1917
1918 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1919 if (!from->is_survivor()) {
1920 _g1_rem->par_write_ref(from, p, tid);
1921 }
1922 }
1923
1924 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1925 // If the new value of the field points to the same region or
1926 // is the to-space, we don't need to include it in the Rset updates.
1927 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1928 size_t card_index = ctbs()->index_for(p);
1929 // If the card hasn't been added to the buffer, do it.
1930 if (ctbs()->mark_card_deferred(card_index)) {
1931 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1932 }
1933 }
1934 }
1935
1936 public:
1937 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1938
1939 ~G1ParScanThreadState() {
1940 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1941 }
1942
1943 RefToScanQueue* refs() { return _refs; }
1944 ageTable* age_table() { return &_age_table; }
1945
1946 G1ParGCAllocBufferContainer* alloc_buffer(GCAllocPurpose purpose) {
1947 return _alloc_buffers[purpose];
1948 }
1949
1950 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1951 size_t undo_waste() const { return _undo_waste; }
1952
1953 #ifdef ASSERT
1954 bool verify_ref(narrowOop* ref) const;
1955 bool verify_ref(oop* ref) const;
1956 bool verify_task(StarTask ref) const;
1957 #endif // ASSERT
1958
1959 template <class T> void push_on_queue(T* ref) {
1960 assert(verify_ref(ref), "sanity");
1961 refs()->push(ref);
1962 }
1963
1964 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1965 if (G1DeferredRSUpdate) {
1966 deferred_rs_update(from, p, tid);
1967 } else {
1968 immediate_rs_update(from, p, tid);
1969 }
1970 }
1971
1972 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1973 HeapWord* obj = NULL;
1974 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1975 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1976 G1ParGCAllocBufferContainer* alloc_buf = alloc_buffer(purpose);
1977
1978 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1979 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1980
1981 add_to_alloc_buffer_waste(alloc_buf->words_remaining_in_retired_buffer());
1982 alloc_buf->update(false /* end_of_gc */, false /* retain */, buf, gclab_word_size);
1983
1984 obj = alloc_buf->allocate(word_sz);
1985 assert(obj != NULL, "buffer was definitely big enough...");
1986 } else {
1987 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1988 }
1989 return obj;
1990 }
1991
1992 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1993 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1994 if (obj != NULL) return obj;
1995 return allocate_slow(purpose, word_sz);
1996 }
1997
1998 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1999 if (alloc_buffer(purpose)->contains(obj)) {
2000 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2001 "should contain whole object");
2002 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2003 } else {
2004 CollectedHeap::fill_with_object(obj, word_sz);
2005 add_to_undo_waste(word_sz);
2006 }
2007 }
2008
2009 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2010 _evac_failure_cl = evac_failure_cl;
2011 }
2012 OopsInHeapRegionClosure* evac_failure_closure() {
2013 return _evac_failure_cl;
2014 }
2015
2016 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2017 _evac_cl = evac_cl;
2018 }
2019
2020 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2021 _partial_scan_cl = partial_scan_cl;
2022 }
2023
2024 int* hash_seed() { return &_hash_seed; }
2025 uint queue_num() { return _queue_num; }
2026
2027 size_t term_attempts() const { return _term_attempts; }
2028 void note_term_attempt() { _term_attempts++; }
2029
2030 void start_strong_roots() {
2031 _start_strong_roots = os::elapsedTime();
2032 }
2033 void end_strong_roots() {
2034 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2035 }
2036 double strong_roots_time() const { return _strong_roots_time; }
2037
2038 void start_term_time() {
2039 note_term_attempt();
2040 _start_term = os::elapsedTime();
2041 }
2042 void end_term_time() {
2043 _term_time += (os::elapsedTime() - _start_term);
2044 }
2045 double term_time() const { return _term_time; }
2046
2047 double elapsed_time() const {
2048 return os::elapsedTime() - _start;
2049 }
2050
2051 static void
2052 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2053 void
2054 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2055
2056 size_t* surviving_young_words() {
2057 // We add on to hide entry 0 which accumulates surviving words for
2058 // age -1 regions (i.e. non-young ones)
2059 return _surviving_young_words;
2060 }
2061
2062 void retire_alloc_buffers() {
2063 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2064 size_t waste = _alloc_buffers[ap]->words_remaining();
2065 add_to_alloc_buffer_waste(waste);
2066 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
2067 true /* end_of_gc */,
2068 false /* retain */);
2069 }
2070 }
2071
2072 template <class T> void deal_with_reference(T* ref_to_scan) {
2073 if (has_partial_array_mask(ref_to_scan)) {
2074 _partial_scan_cl->do_oop_nv(ref_to_scan);
2075 } else {
2076 // Note: we can use "raw" versions of "region_containing" because
2077 // "obj_to_scan" is definitely in the heap, and is not in a
2078 // humongous region.
2079 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2080 _evac_cl->set_region(r);
2081 _evac_cl->do_oop_nv(ref_to_scan);
2082 }
2083 }
2084
2085 void deal_with_reference(StarTask ref) {
2086 assert(verify_task(ref), "sanity");
2087 if (ref.is_narrow()) {
2088 deal_with_reference((narrowOop*)ref);
2089 } else {
2090 deal_with_reference((oop*)ref);
2091 }
2092 }
2093
2094 void trim_queue();
2095 };
2096
2097 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP