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.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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/g1SATBCardTableModRefBS.hpp"
35 #include "gc_implementation/g1/g1YCTypes.hpp"
36 #include "gc_implementation/g1/heapRegionSeq.hpp"
37 #include "gc_implementation/g1/heapRegionSets.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"
44
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.
49
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
76 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
77 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
78
79 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
80 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
81
82 enum GCAllocPurpose {
83 GCAllocForTenured,
84 GCAllocForSurvived,
85 GCAllocPurposeCount
86 };
87
88 class YoungList : public CHeapObj<mtGC> {
89 private:
90 G1CollectedHeap* _g1h;
91
92 HeapRegion* _head;
93
94 HeapRegion* _survivor_head;
95 HeapRegion* _survivor_tail;
96
97 HeapRegion* _curr;
98
99 uint _length;
100 uint _survivor_length;
101
102 size_t _last_sampled_rs_lengths;
103 size_t _sampled_rs_lengths;
104
105 void empty_list(HeapRegion* list);
106
107 public:
108 YoungList(G1CollectedHeap* g1h);
109
110 void push_region(HeapRegion* hr);
111 void add_survivor_region(HeapRegion* hr);
112
113 void empty_list();
114 bool is_empty() { return _length == 0; }
115 uint length() { return _length; }
116 uint survivor_length() { return _survivor_length; }
117
118 // Currently we do not keep track of the used byte sum for the
119 // young list and the survivors and it'd be quite a lot of work to
120 // do so. When we'll eventually replace the young list with
121 // instances of HeapRegionLinkedList we'll get that for free. So,
122 // we'll report the more accurate information then.
123 size_t eden_used_bytes() {
124 assert(length() >= survivor_length(), "invariant");
125 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
126 }
127 size_t survivor_used_bytes() {
128 return (size_t) survivor_length() * HeapRegion::GrainBytes;
129 }
130
131 void rs_length_sampling_init();
132 bool rs_length_sampling_more();
133 void rs_length_sampling_next();
134
135 void reset_sampled_info() {
136 _last_sampled_rs_lengths = 0;
137 }
138 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
139
140 // for development purposes
141 void reset_auxilary_lists();
142 void clear() { _head = NULL; _length = 0; }
143
144 void clear_survivors() {
145 _survivor_head = NULL;
146 _survivor_tail = NULL;
147 _survivor_length = 0;
148 }
149
150 HeapRegion* first_region() { return _head; }
151 HeapRegion* first_survivor_region() { return _survivor_head; }
152 HeapRegion* last_survivor_region() { return _survivor_tail; }
153
154 // debugging
155 bool check_list_well_formed();
156 bool check_list_empty(bool check_sample = true);
157 void print();
158 };
159
160 class MutatorAllocRegion : public G1AllocRegion {
161 protected:
162 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
163 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
164 public:
165 MutatorAllocRegion()
166 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
167 };
168
169 class SurvivorGCAllocRegion : public G1AllocRegion {
170 protected:
171 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
172 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
173 public:
174 SurvivorGCAllocRegion()
175 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
176 };
177
178 class OldGCAllocRegion : public G1AllocRegion {
179 protected:
180 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
181 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
182 public:
183 OldGCAllocRegion()
184 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
185 };
186
187 // The G1 STW is alive closure.
188 // An instance is embedded into the G1CH and used as the
189 // (optional) _is_alive_non_header closure in the STW
190 // reference processor. It is also extensively used during
191 // reference processing during STW evacuation pauses.
192 class G1STWIsAliveClosure: public BoolObjectClosure {
193 G1CollectedHeap* _g1;
194 public:
195 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
196 bool do_object_b(oop p);
197 };
198
199 class RefineCardTableEntryClosure;
200
201 class G1CollectedHeap : public SharedHeap {
202 friend class VM_G1CollectForAllocation;
203 friend class VM_G1CollectFull;
204 friend class VM_G1IncCollectionPause;
205 friend class VMStructs;
206 friend class MutatorAllocRegion;
207 friend class SurvivorGCAllocRegion;
208 friend class OldGCAllocRegion;
209
210 // Closures used in implementation.
211 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
212 friend class G1ParCopyClosure;
213 friend class G1IsAliveClosure;
214 friend class G1EvacuateFollowersClosure;
215 friend class G1ParScanThreadState;
216 friend class G1ParScanClosureSuper;
217 friend class G1ParEvacuateFollowersClosure;
218 friend class G1ParTask;
219 friend class G1FreeGarbageRegionClosure;
220 friend class RefineCardTableEntryClosure;
221 friend class G1PrepareCompactClosure;
222 friend class RegionSorter;
223 friend class RegionResetter;
224 friend class CountRCClosure;
225 friend class EvacPopObjClosure;
226 friend class G1ParCleanupCTTask;
227
228 // Other related classes.
229 friend class G1MarkSweep;
230
231 private:
232 // The one and only G1CollectedHeap, so static functions can find it.
233 static G1CollectedHeap* _g1h;
234
235 static size_t _humongous_object_threshold_in_words;
236
237 // Storage for the G1 heap.
238 VirtualSpace _g1_storage;
239 MemRegion _g1_reserved;
240
241 // The part of _g1_storage that is currently committed.
242 MemRegion _g1_committed;
243
244 // The master free list. It will satisfy all new region allocations.
245 MasterFreeRegionList _free_list;
246
247 // The secondary free list which contains regions that have been
248 // freed up during the cleanup process. This will be appended to the
249 // master free list when appropriate.
250 SecondaryFreeRegionList _secondary_free_list;
251
252 // It keeps track of the old regions.
253 MasterOldRegionSet _old_set;
254
255 // It keeps track of the humongous regions.
256 MasterHumongousRegionSet _humongous_set;
257
258 // The number of regions we could create by expansion.
259 uint _expansion_regions;
260
261 // The block offset table for the G1 heap.
262 G1BlockOffsetSharedArray* _bot_shared;
263
264 // Tears down the region sets / lists so that they are empty and the
265 // regions on the heap do not belong to a region set / list. The
266 // only exception is the humongous set which we leave unaltered. If
267 // free_list_only is true, it will only tear down the master free
268 // list. It is called before a Full GC (free_list_only == false) or
269 // before heap shrinking (free_list_only == true).
270 void tear_down_region_sets(bool free_list_only);
271
272 // Rebuilds the region sets / lists so that they are repopulated to
273 // reflect the contents of the heap. The only exception is the
274 // humongous set which was not torn down in the first place. If
275 // free_list_only is true, it will only rebuild the master free
276 // list. It is called after a Full GC (free_list_only == false) or
277 // after heap shrinking (free_list_only == true).
278 void rebuild_region_sets(bool free_list_only);
279
280 // The sequence of all heap regions in the heap.
281 HeapRegionSeq _hrs;
282
283 // Alloc region used to satisfy mutator allocation requests.
284 MutatorAllocRegion _mutator_alloc_region;
285
286 // Alloc region used to satisfy allocation requests by the GC for
287 // survivor objects.
288 SurvivorGCAllocRegion _survivor_gc_alloc_region;
289
290 // PLAB sizing policy for survivors.
291 PLABStats _survivor_plab_stats;
292
293 // Alloc region used to satisfy allocation requests by the GC for
294 // old objects.
295 OldGCAllocRegion _old_gc_alloc_region;
296
297 // PLAB sizing policy for tenured objects.
298 PLABStats _old_plab_stats;
299
300 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
301 PLABStats* stats = NULL;
302
303 switch (purpose) {
304 case GCAllocForSurvived:
305 stats = &_survivor_plab_stats;
306 break;
307 case GCAllocForTenured:
308 stats = &_old_plab_stats;
309 break;
310 default:
311 assert(false, "unrecognized GCAllocPurpose");
312 }
313
314 return stats;
315 }
316
317 // The last old region we allocated to during the last GC.
318 // Typically, it is not full so we should re-use it during the next GC.
319 HeapRegion* _retained_old_gc_alloc_region;
320
321 // It specifies whether we should attempt to expand the heap after a
322 // region allocation failure. If heap expansion fails we set this to
323 // false so that we don't re-attempt the heap expansion (it's likely
324 // that subsequent expansion attempts will also fail if one fails).
325 // Currently, it is only consulted during GC and it's reset at the
326 // start of each GC.
327 bool _expand_heap_after_alloc_failure;
328
329 // It resets the mutator alloc region before new allocations can take place.
330 void init_mutator_alloc_region();
331
332 // It releases the mutator alloc region.
333 void release_mutator_alloc_region();
334
335 // It initializes the GC alloc regions at the start of a GC.
336 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
337
338 // It releases the GC alloc regions at the end of a GC.
339 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
340
341 // It does any cleanup that needs to be done on the GC alloc regions
342 // before a Full GC.
343 void abandon_gc_alloc_regions();
344
345 // Helper for monitoring and management support.
346 G1MonitoringSupport* _g1mm;
347
348 // Determines PLAB size for a particular allocation purpose.
349 size_t desired_plab_sz(GCAllocPurpose purpose);
350
351 // Outside of GC pauses, the number of bytes used in all regions other
352 // than the current allocation region.
353 size_t _summary_bytes_used;
354
355 // This is used for a quick test on whether a reference points into
356 // the collection set or not. Basically, we have an array, with one
357 // byte per region, and that byte denotes whether the corresponding
358 // region is in the collection set or not. The entry corresponding
359 // the bottom of the heap, i.e., region 0, is pointed to by
360 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
361 // biased so that it actually points to address 0 of the address
362 // space, to make the test as fast as possible (we can simply shift
363 // the address to address into it, instead of having to subtract the
364 // bottom of the heap from the address before shifting it; basically
365 // it works in the same way the card table works).
366 bool* _in_cset_fast_test;
367
368 // The allocated array used for the fast test on whether a reference
369 // points into the collection set or not. This field is also used to
370 // free the array.
371 bool* _in_cset_fast_test_base;
372
373 // The length of the _in_cset_fast_test_base array.
374 uint _in_cset_fast_test_length;
375
376 volatile unsigned _gc_time_stamp;
377
378 size_t* _surviving_young_words;
379
380 G1HRPrinter _hr_printer;
381
382 void setup_surviving_young_words();
383 void update_surviving_young_words(size_t* surv_young_words);
384 void cleanup_surviving_young_words();
385
386 // It decides whether an explicit GC should start a concurrent cycle
387 // instead of doing a STW GC. Currently, a concurrent cycle is
388 // explicitly started if:
389 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
390 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
391 // (c) cause == _g1_humongous_allocation
392 bool should_do_concurrent_full_gc(GCCause::Cause cause);
393
394 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
395 // concurrent cycles) we have started.
396 volatile unsigned int _old_marking_cycles_started;
397
398 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
399 // concurrent cycles) we have completed.
400 volatile unsigned int _old_marking_cycles_completed;
401
402 bool _concurrent_cycle_started;
403
404 // This is a non-product method that is helpful for testing. It is
405 // called at the end of a GC and artificially expands the heap by
406 // allocating a number of dead regions. This way we can induce very
407 // frequent marking cycles and stress the cleanup / concurrent
408 // cleanup code more (as all the regions that will be allocated by
409 // this method will be found dead by the marking cycle).
410 void allocate_dummy_regions() PRODUCT_RETURN;
411
412 // Clear RSets after a compaction. It also resets the GC time stamps.
413 void clear_rsets_post_compaction();
414
415 // If the HR printer is active, dump the state of the regions in the
416 // heap after a compaction.
417 void print_hrs_post_compaction();
418
419 double verify(bool guard, const char* msg);
420 void verify_before_gc();
421 void verify_after_gc();
422
423 void log_gc_header();
424 void log_gc_footer(double pause_time_sec);
425
426 // These are macros so that, if the assert fires, we get the correct
427 // line number, file, etc.
428
429 #define heap_locking_asserts_err_msg(_extra_message_) \
430 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
431 (_extra_message_), \
432 BOOL_TO_STR(Heap_lock->owned_by_self()), \
433 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
434 BOOL_TO_STR(Thread::current()->is_VM_thread()))
435
436 #define assert_heap_locked() \
437 do { \
438 assert(Heap_lock->owned_by_self(), \
439 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
440 } while (0)
441
442 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
443 do { \
444 assert(Heap_lock->owned_by_self() || \
445 (SafepointSynchronize::is_at_safepoint() && \
446 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
447 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
448 "should be at a safepoint")); \
449 } while (0)
450
451 #define assert_heap_locked_and_not_at_safepoint() \
452 do { \
453 assert(Heap_lock->owned_by_self() && \
454 !SafepointSynchronize::is_at_safepoint(), \
455 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
456 "should not be at a safepoint")); \
457 } while (0)
458
459 #define assert_heap_not_locked() \
460 do { \
461 assert(!Heap_lock->owned_by_self(), \
462 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
463 } while (0)
464
465 #define assert_heap_not_locked_and_not_at_safepoint() \
466 do { \
467 assert(!Heap_lock->owned_by_self() && \
468 !SafepointSynchronize::is_at_safepoint(), \
469 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
470 "should not be at a safepoint")); \
471 } while (0)
472
473 #define assert_at_safepoint(_should_be_vm_thread_) \
474 do { \
475 assert(SafepointSynchronize::is_at_safepoint() && \
476 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
477 heap_locking_asserts_err_msg("should be at a safepoint")); \
478 } while (0)
479
480 #define assert_not_at_safepoint() \
481 do { \
482 assert(!SafepointSynchronize::is_at_safepoint(), \
483 heap_locking_asserts_err_msg("should not be at a safepoint")); \
484 } while (0)
485
486 protected:
487
488 // The young region list.
489 YoungList* _young_list;
490
491 // The current policy object for the collector.
492 G1CollectorPolicy* _g1_policy;
493
494 // This is the second level of trying to allocate a new region. If
495 // new_region() didn't find a region on the free_list, this call will
496 // check whether there's anything available on the
497 // secondary_free_list and/or wait for more regions to appear on
498 // that list, if _free_regions_coming is set.
499 HeapRegion* new_region_try_secondary_free_list();
500
501 // Try to allocate a single non-humongous HeapRegion sufficient for
502 // an allocation of the given word_size. If do_expand is true,
503 // attempt to expand the heap if necessary to satisfy the allocation
504 // request.
505 HeapRegion* new_region(size_t word_size, bool do_expand);
506
507 // Attempt to satisfy a humongous allocation request of the given
508 // size by finding a contiguous set of free regions of num_regions
509 // length and remove them from the master free list. Return the
510 // index of the first region or G1_NULL_HRS_INDEX if the search
511 // was unsuccessful.
512 uint humongous_obj_allocate_find_first(uint num_regions,
513 size_t word_size);
514
515 // Initialize a contiguous set of free regions of length num_regions
516 // and starting at index first so that they appear as a single
517 // humongous region.
518 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
519 uint num_regions,
520 size_t word_size);
521
522 // Attempt to allocate a humongous object of the given size. Return
523 // NULL if unsuccessful.
524 HeapWord* humongous_obj_allocate(size_t word_size);
525
526 // The following two methods, allocate_new_tlab() and
527 // mem_allocate(), are the two main entry points from the runtime
528 // into the G1's allocation routines. They have the following
529 // assumptions:
530 //
531 // * They should both be called outside safepoints.
532 //
533 // * They should both be called without holding the Heap_lock.
534 //
535 // * All allocation requests for new TLABs should go to
536 // allocate_new_tlab().
537 //
538 // * All non-TLAB allocation requests should go to mem_allocate().
539 //
540 // * If either call cannot satisfy the allocation request using the
541 // current allocating region, they will try to get a new one. If
542 // this fails, they will attempt to do an evacuation pause and
543 // retry the allocation.
544 //
545 // * If all allocation attempts fail, even after trying to schedule
546 // an evacuation pause, allocate_new_tlab() will return NULL,
547 // whereas mem_allocate() will attempt a heap expansion and/or
548 // schedule a Full GC.
549 //
550 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
551 // should never be called with word_size being humongous. All
552 // humongous allocation requests should go to mem_allocate() which
553 // will satisfy them with a special path.
554
555 virtual HeapWord* allocate_new_tlab(size_t word_size);
556
557 virtual HeapWord* mem_allocate(size_t word_size,
558 bool* gc_overhead_limit_was_exceeded);
559
560 // The following three methods take a gc_count_before_ret
561 // parameter which is used to return the GC count if the method
562 // returns NULL. Given that we are required to read the GC count
563 // while holding the Heap_lock, and these paths will take the
564 // Heap_lock at some point, it's easier to get them to read the GC
565 // count while holding the Heap_lock before they return NULL instead
566 // of the caller (namely: mem_allocate()) having to also take the
567 // Heap_lock just to read the GC count.
568
569 // First-level mutator allocation attempt: try to allocate out of
570 // the mutator alloc region without taking the Heap_lock. This
571 // should only be used for non-humongous allocations.
572 inline HeapWord* attempt_allocation(size_t word_size,
573 unsigned int* gc_count_before_ret,
574 int* gclocker_retry_count_ret);
575
576 // Second-level mutator allocation attempt: take the Heap_lock and
577 // retry the allocation attempt, potentially scheduling a GC
578 // pause. This should only be used for non-humongous allocations.
579 HeapWord* attempt_allocation_slow(size_t word_size,
580 unsigned int* gc_count_before_ret,
581 int* gclocker_retry_count_ret);
582
583 // Takes the Heap_lock and attempts a humongous allocation. It can
584 // potentially schedule a GC pause.
585 HeapWord* attempt_allocation_humongous(size_t word_size,
586 unsigned int* gc_count_before_ret,
587 int* gclocker_retry_count_ret);
588
589 // Allocation attempt that should be called during safepoints (e.g.,
590 // at the end of a successful GC). expect_null_mutator_alloc_region
591 // specifies whether the mutator alloc region is expected to be NULL
592 // or not.
593 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
594 bool expect_null_mutator_alloc_region);
595
596 // It dirties the cards that cover the block so that so that the post
597 // write barrier never queues anything when updating objects on this
598 // block. It is assumed (and in fact we assert) that the block
599 // belongs to a young region.
600 inline void dirty_young_block(HeapWord* start, size_t word_size);
601
602 // Allocate blocks during garbage collection. Will ensure an
603 // allocation region, either by picking one or expanding the
604 // heap, and then allocate a block of the given size. The block
605 // may not be a humongous - it must fit into a single heap region.
606 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
607
608 // Ensure that no further allocations can happen in "r", bearing in mind
609 // that parallel threads might be attempting allocations.
610 void par_allocate_remaining_space(HeapRegion* r);
611
612 // Allocation attempt during GC for a survivor object / PLAB.
613 inline HeapWord* survivor_attempt_allocation(size_t word_size);
614
615 // Allocation attempt during GC for an old object / PLAB.
616 inline HeapWord* old_attempt_allocation(size_t word_size);
617
618 // These methods are the "callbacks" from the G1AllocRegion class.
619
620 // For mutator alloc regions.
621 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
622 void retire_mutator_alloc_region(HeapRegion* alloc_region,
623 size_t allocated_bytes);
624
625 // For GC alloc regions.
626 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
627 GCAllocPurpose ap);
628 void retire_gc_alloc_region(HeapRegion* alloc_region,
629 size_t allocated_bytes, GCAllocPurpose ap);
630
631 // - if explicit_gc is true, the GC is for a System.gc() or a heap
632 // inspection request and should collect the entire heap
633 // - if clear_all_soft_refs is true, all soft references should be
634 // cleared during the GC
635 // - if explicit_gc is false, word_size describes the allocation that
636 // the GC should attempt (at least) to satisfy
637 // - it returns false if it is unable to do the collection due to the
638 // GC locker being active, true otherwise
639 bool do_collection(bool explicit_gc,
640 bool clear_all_soft_refs,
641 size_t word_size);
642
643 // Callback from VM_G1CollectFull operation.
644 // Perform a full collection.
645 virtual void do_full_collection(bool clear_all_soft_refs);
646
647 // Resize the heap if necessary after a full collection. If this is
648 // after a collect-for allocation, "word_size" is the allocation size,
649 // and will be considered part of the used portion of the heap.
650 void resize_if_necessary_after_full_collection(size_t word_size);
651
652 // Callback from VM_G1CollectForAllocation operation.
653 // This function does everything necessary/possible to satisfy a
654 // failed allocation request (including collection, expansion, etc.)
655 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
656
657 // Attempting to expand the heap sufficiently
658 // to support an allocation of the given "word_size". If
659 // successful, perform the allocation and return the address of the
660 // allocated block, or else "NULL".
661 HeapWord* expand_and_allocate(size_t word_size);
662
663 // Process any reference objects discovered during
664 // an incremental evacuation pause.
665 void process_discovered_references(uint no_of_gc_workers);
666
667 // Enqueue any remaining discovered references
668 // after processing.
669 void enqueue_discovered_references(uint no_of_gc_workers);
670
671 public:
672
673 G1MonitoringSupport* g1mm() {
674 assert(_g1mm != NULL, "should have been initialized");
675 return _g1mm;
676 }
677
678 // Expand the garbage-first heap by at least the given size (in bytes!).
679 // Returns true if the heap was expanded by the requested amount;
680 // false otherwise.
681 // (Rounds up to a HeapRegion boundary.)
682 bool expand(size_t expand_bytes);
683
684 // Do anything common to GC's.
685 virtual void gc_prologue(bool full);
686 virtual void gc_epilogue(bool full);
687
688 // We register a region with the fast "in collection set" test. We
689 // simply set to true the array slot corresponding to this region.
690 void register_region_with_in_cset_fast_test(HeapRegion* r) {
691 assert(_in_cset_fast_test_base != NULL, "sanity");
692 assert(r->in_collection_set(), "invariant");
693 uint index = r->hrs_index();
694 assert(index < _in_cset_fast_test_length, "invariant");
695 assert(!_in_cset_fast_test_base[index], "invariant");
696 _in_cset_fast_test_base[index] = true;
697 }
698
699 // This is a fast test on whether a reference points into the
700 // collection set or not. It does not assume that the reference
701 // points into the heap; if it doesn't, it will return false.
702 bool in_cset_fast_test(oop obj) {
703 assert(_in_cset_fast_test != NULL, "sanity");
704 if (_g1_committed.contains((HeapWord*) obj)) {
705 // no need to subtract the bottom of the heap from obj,
706 // _in_cset_fast_test is biased
707 uintx index = cast_from_oop<uintx>(obj) >> HeapRegion::LogOfHRGrainBytes;
708 bool ret = _in_cset_fast_test[index];
709 // let's make sure the result is consistent with what the slower
710 // test returns
711 assert( ret || !obj_in_cs(obj), "sanity");
712 assert(!ret || obj_in_cs(obj), "sanity");
713 return ret;
714 } else {
715 return false;
716 }
717 }
718
719 void clear_cset_fast_test() {
720 assert(_in_cset_fast_test_base != NULL, "sanity");
721 memset(_in_cset_fast_test_base, false,
722 (size_t) _in_cset_fast_test_length * sizeof(bool));
723 }
724
725 // This is called at the start of either a concurrent cycle or a Full
726 // GC to update the number of old marking cycles started.
727 void increment_old_marking_cycles_started();
728
729 // This is called at the end of either a concurrent cycle or a Full
730 // GC to update the number of old marking cycles completed. Those two
731 // can happen in a nested fashion, i.e., we start a concurrent
732 // cycle, a Full GC happens half-way through it which ends first,
733 // and then the cycle notices that a Full GC happened and ends
734 // too. The concurrent parameter is a boolean to help us do a bit
735 // tighter consistency checking in the method. If concurrent is
736 // false, the caller is the inner caller in the nesting (i.e., the
737 // Full GC). If concurrent is true, the caller is the outer caller
738 // in this nesting (i.e., the concurrent cycle). Further nesting is
739 // not currently supported. The end of this call also notifies
740 // the FullGCCount_lock in case a Java thread is waiting for a full
741 // GC to happen (e.g., it called System.gc() with
742 // +ExplicitGCInvokesConcurrent).
743 void increment_old_marking_cycles_completed(bool concurrent);
744
745 unsigned int old_marking_cycles_completed() {
746 return _old_marking_cycles_completed;
747 }
748
749 void register_concurrent_cycle_start(jlong start_time);
750 void register_concurrent_cycle_end();
751 void trace_heap_after_concurrent_cycle();
752
753 G1YCType yc_type();
754
755 G1HRPrinter* hr_printer() { return &_hr_printer; }
756
757 protected:
758
759 // Shrink the garbage-first heap by at most the given size (in bytes!).
760 // (Rounds down to a HeapRegion boundary.)
761 virtual void shrink(size_t expand_bytes);
762 void shrink_helper(size_t expand_bytes);
763
764 #if TASKQUEUE_STATS
765 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
766 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
767 void reset_taskqueue_stats();
768 #endif // TASKQUEUE_STATS
769
770 // Schedule the VM operation that will do an evacuation pause to
771 // satisfy an allocation request of word_size. *succeeded will
772 // return whether the VM operation was successful (it did do an
773 // evacuation pause) or not (another thread beat us to it or the GC
774 // locker was active). Given that we should not be holding the
775 // Heap_lock when we enter this method, we will pass the
776 // gc_count_before (i.e., total_collections()) as a parameter since
777 // it has to be read while holding the Heap_lock. Currently, both
778 // methods that call do_collection_pause() release the Heap_lock
779 // before the call, so it's easy to read gc_count_before just before.
780 HeapWord* do_collection_pause(size_t word_size,
781 unsigned int gc_count_before,
782 bool* succeeded,
783 GCCause::Cause gc_cause);
784
785 // The guts of the incremental collection pause, executed by the vm
786 // thread. It returns false if it is unable to do the collection due
787 // to the GC locker being active, true otherwise
788 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
789
790 // Actually do the work of evacuating the collection set.
791 void evacuate_collection_set(EvacuationInfo& evacuation_info);
792
793 // The g1 remembered set of the heap.
794 G1RemSet* _g1_rem_set;
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
1130 unsigned get_gc_time_stamp() {
1131 return _gc_time_stamp;
1132 }
1133
1134 void reset_gc_time_stamp() {
1135 _gc_time_stamp = 0;
1136 OrderAccess::fence();
1137 // Clear the cached CSet starting regions and time stamps.
1138 // Their validity is dependent on the GC timestamp.
1139 clear_cset_start_regions();
1140 }
1141
1142 void check_gc_time_stamps() PRODUCT_RETURN;
1143
1144 void increment_gc_time_stamp() {
1145 ++_gc_time_stamp;
1146 OrderAccess::fence();
1147 }
1148
1149 // Reset the given region's GC timestamp. If it's starts humongous,
1150 // also reset the GC timestamp of its corresponding
1151 // continues humongous regions too.
1152 void reset_gc_time_stamps(HeapRegion* hr);
1153
1154 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1155 DirtyCardQueue* into_cset_dcq,
1156 bool concurrent, int worker_i);
1157
1158 // The shared block offset table array.
1159 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1160
1161 // Reference Processing accessors
1162
1163 // The STW reference processor....
1164 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1165
1166 // The Concurrent Marking reference processor...
1167 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1168
1169 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1170 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1171
1172 virtual size_t capacity() const;
1173 virtual size_t used() const;
1174 // This should be called when we're not holding the heap lock. The
1175 // result might be a bit inaccurate.
1176 size_t used_unlocked() const;
1177 size_t recalculate_used() const;
1178
1179 // These virtual functions do the actual allocation.
1180 // Some heaps may offer a contiguous region for shared non-blocking
1181 // allocation, via inlined code (by exporting the address of the top and
1182 // end fields defining the extent of the contiguous allocation region.)
1183 // But G1CollectedHeap doesn't yet support this.
1184
1185 // Return an estimate of the maximum allocation that could be performed
1186 // without triggering any collection or expansion activity. In a
1187 // generational collector, for example, this is probably the largest
1188 // allocation that could be supported (without expansion) in the youngest
1189 // generation. It is "unsafe" because no locks are taken; the result
1190 // should be treated as an approximation, not a guarantee, for use in
1191 // heuristic resizing decisions.
1192 virtual size_t unsafe_max_alloc();
1193
1194 virtual bool is_maximal_no_gc() const {
1195 return _g1_storage.uncommitted_size() == 0;
1196 }
1197
1198 // The total number of regions in the heap.
1199 uint n_regions() { return _hrs.length(); }
1200
1201 // The max number of regions in the heap.
1202 uint max_regions() { return _hrs.max_length(); }
1203
1204 // The number of regions that are completely free.
1205 uint free_regions() { return _free_list.length(); }
1206
1207 // The number of regions that are not completely free.
1208 uint used_regions() { return n_regions() - free_regions(); }
1209
1210 // The number of regions available for "regular" expansion.
1211 uint expansion_regions() { return _expansion_regions; }
1212
1213 // Factory method for HeapRegion instances. It will return NULL if
1214 // the allocation fails.
1215 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1216
1217 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1218 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1219 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1220 void verify_dirty_young_regions() PRODUCT_RETURN;
1221
1222 // verify_region_sets() performs verification over the region
1223 // lists. It will be compiled in the product code to be used when
1224 // necessary (i.e., during heap verification).
1225 void verify_region_sets();
1226
1227 // verify_region_sets_optional() is planted in the code for
1228 // list verification in non-product builds (and it can be enabled in
1229 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1230 #if HEAP_REGION_SET_FORCE_VERIFY
1231 void verify_region_sets_optional() {
1232 verify_region_sets();
1233 }
1234 #else // HEAP_REGION_SET_FORCE_VERIFY
1235 void verify_region_sets_optional() { }
1236 #endif // HEAP_REGION_SET_FORCE_VERIFY
1237
1238 #ifdef ASSERT
1239 bool is_on_master_free_list(HeapRegion* hr) {
1240 return hr->containing_set() == &_free_list;
1241 }
1242
1243 bool is_in_humongous_set(HeapRegion* hr) {
1244 return hr->containing_set() == &_humongous_set;
1245 }
1246 #endif // ASSERT
1247
1248 // Wrapper for the region list operations that can be called from
1249 // methods outside this class.
1250
1251 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1252 _secondary_free_list.add_as_tail(list);
1253 }
1254
1255 void append_secondary_free_list() {
1256 _free_list.add_as_head(&_secondary_free_list);
1257 }
1258
1259 void append_secondary_free_list_if_not_empty_with_lock() {
1260 // If the secondary free list looks empty there's no reason to
1261 // take the lock and then try to append it.
1262 if (!_secondary_free_list.is_empty()) {
1263 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1264 append_secondary_free_list();
1265 }
1266 }
1267
1268 void old_set_remove(HeapRegion* hr) {
1269 _old_set.remove(hr);
1270 }
1271
1272 size_t non_young_capacity_bytes() {
1273 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1274 }
1275
1276 void set_free_regions_coming();
1277 void reset_free_regions_coming();
1278 bool free_regions_coming() { return _free_regions_coming; }
1279 void wait_while_free_regions_coming();
1280
1281 // Determine whether the given region is one that we are using as an
1282 // old GC alloc region.
1283 bool is_old_gc_alloc_region(HeapRegion* hr) {
1284 return hr == _retained_old_gc_alloc_region;
1285 }
1286
1287 // Perform a collection of the heap; intended for use in implementing
1288 // "System.gc". This probably implies as full a collection as the
1289 // "CollectedHeap" supports.
1290 virtual void collect(GCCause::Cause cause);
1291
1292 // The same as above but assume that the caller holds the Heap_lock.
1293 void collect_locked(GCCause::Cause cause);
1294
1295 // True iff an evacuation has failed in the most-recent collection.
1296 bool evacuation_failed() { return _evacuation_failed; }
1297
1298 // It will free a region if it has allocated objects in it that are
1299 // all dead. It calls either free_region() or
1300 // free_humongous_region() depending on the type of the region that
1301 // is passed to it.
1302 void free_region_if_empty(HeapRegion* hr,
1303 size_t* pre_used,
1304 FreeRegionList* free_list,
1305 OldRegionSet* old_proxy_set,
1306 HumongousRegionSet* humongous_proxy_set,
1307 HRRSCleanupTask* hrrs_cleanup_task,
1308 bool par);
1309
1310 // It appends the free list to the master free list and updates the
1311 // master humongous list according to the contents of the proxy
1312 // list. It also adjusts the total used bytes according to pre_used
1313 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1314 void update_sets_after_freeing_regions(size_t pre_used,
1315 FreeRegionList* free_list,
1316 OldRegionSet* old_proxy_set,
1317 HumongousRegionSet* humongous_proxy_set,
1318 bool par);
1319
1320 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1321 virtual bool is_in(const void* p) const;
1322
1323 // Return "TRUE" iff the given object address is within the collection
1324 // set.
1325 inline bool obj_in_cs(oop obj);
1326
1327 // Return "TRUE" iff the given object address is in the reserved
1328 // region of g1.
1329 bool is_in_g1_reserved(const void* p) const {
1330 return _g1_reserved.contains(p);
1331 }
1332
1333 // Returns a MemRegion that corresponds to the space that has been
1334 // reserved for the heap
1335 MemRegion g1_reserved() {
1336 return _g1_reserved;
1337 }
1338
1339 // Returns a MemRegion that corresponds to the space that has been
1340 // committed in the heap
1341 MemRegion g1_committed() {
1342 return _g1_committed;
1343 }
1344
1345 virtual bool is_in_closed_subset(const void* p) const;
1346
1347 G1SATBCardTableModRefBS* g1_barrier_set() {
1348 return (G1SATBCardTableModRefBS*) barrier_set();
1349 }
1350
1351 // This resets the card table to all zeros. It is used after
1352 // a collection pause which used the card table to claim cards.
1353 void cleanUpCardTable();
1354
1355 // Iteration functions.
1356
1357 // Iterate over all the ref-containing fields of all objects, calling
1358 // "cl.do_oop" on each.
1359 virtual void oop_iterate(ExtendedOopClosure* cl);
1360
1361 // Same as above, restricted to a memory region.
1362 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1363
1364 // Iterate over all objects, calling "cl.do_object" on each.
1365 virtual void object_iterate(ObjectClosure* cl);
1366
1367 virtual void safe_object_iterate(ObjectClosure* cl) {
1368 object_iterate(cl);
1369 }
1370
1371 // Iterate over all spaces in use in the heap, in ascending address order.
1372 virtual void space_iterate(SpaceClosure* cl);
1373
1374 // Iterate over heap regions, in address order, terminating the
1375 // iteration early if the "doHeapRegion" method returns "true".
1376 void heap_region_iterate(HeapRegionClosure* blk) const;
1377
1378 // Return the region with the given index. It assumes the index is valid.
1379 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1380
1381 // Divide the heap region sequence into "chunks" of some size (the number
1382 // of regions divided by the number of parallel threads times some
1383 // overpartition factor, currently 4). Assumes that this will be called
1384 // in parallel by ParallelGCThreads worker threads with discinct worker
1385 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1386 // calls will use the same "claim_value", and that that claim value is
1387 // different from the claim_value of any heap region before the start of
1388 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1389 // attempting to claim the first region in each chunk, and, if
1390 // successful, applying the closure to each region in the chunk (and
1391 // setting the claim value of the second and subsequent regions of the
1392 // chunk.) For now requires that "doHeapRegion" always returns "false",
1393 // i.e., that a closure never attempt to abort a traversal.
1394 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1395 uint worker,
1396 uint no_of_par_workers,
1397 jint claim_value);
1398
1399 // It resets all the region claim values to the default.
1400 void reset_heap_region_claim_values();
1401
1402 // Resets the claim values of regions in the current
1403 // collection set to the default.
1404 void reset_cset_heap_region_claim_values();
1405
1406 #ifdef ASSERT
1407 bool check_heap_region_claim_values(jint claim_value);
1408
1409 // Same as the routine above but only checks regions in the
1410 // current collection set.
1411 bool check_cset_heap_region_claim_values(jint claim_value);
1412 #endif // ASSERT
1413
1414 // Clear the cached cset start regions and (more importantly)
1415 // the time stamps. Called when we reset the GC time stamp.
1416 void clear_cset_start_regions();
1417
1418 // Given the id of a worker, obtain or calculate a suitable
1419 // starting region for iterating over the current collection set.
1420 HeapRegion* start_cset_region_for_worker(int worker_i);
1421
1422 // This is a convenience method that is used by the
1423 // HeapRegionIterator classes to calculate the starting region for
1424 // each worker so that they do not all start from the same region.
1425 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1426
1427 // Iterate over the regions (if any) in the current collection set.
1428 void collection_set_iterate(HeapRegionClosure* blk);
1429
1430 // As above but starting from region r
1431 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1432
1433 // Returns the first (lowest address) compactible space in the heap.
1434 virtual CompactibleSpace* first_compactible_space();
1435
1436 // A CollectedHeap will contain some number of spaces. This finds the
1437 // space containing a given address, or else returns NULL.
1438 virtual Space* space_containing(const void* addr) const;
1439
1440 // A G1CollectedHeap will contain some number of heap regions. This
1441 // finds the region containing a given address, or else returns NULL.
1442 template <class T>
1443 inline HeapRegion* heap_region_containing(const T addr) const;
1444
1445 // Like the above, but requires "addr" to be in the heap (to avoid a
1446 // null-check), and unlike the above, may return an continuing humongous
1447 // region.
1448 template <class T>
1449 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1450
1451 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1452 // each address in the (reserved) heap is a member of exactly
1453 // one block. The defining characteristic of a block is that it is
1454 // possible to find its size, and thus to progress forward to the next
1455 // block. (Blocks may be of different sizes.) Thus, blocks may
1456 // represent Java objects, or they might be free blocks in a
1457 // free-list-based heap (or subheap), as long as the two kinds are
1458 // distinguishable and the size of each is determinable.
1459
1460 // Returns the address of the start of the "block" that contains the
1461 // address "addr". We say "blocks" instead of "object" since some heaps
1462 // may not pack objects densely; a chunk may either be an object or a
1463 // non-object.
1464 virtual HeapWord* block_start(const void* addr) const;
1465
1466 // Requires "addr" to be the start of a chunk, and returns its size.
1467 // "addr + size" is required to be the start of a new chunk, or the end
1468 // of the active area of the heap.
1469 virtual size_t block_size(const HeapWord* addr) const;
1470
1471 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1472 // the block is an object.
1473 virtual bool block_is_obj(const HeapWord* addr) const;
1474
1475 // Does this heap support heap inspection? (+PrintClassHistogram)
1476 virtual bool supports_heap_inspection() const { return true; }
1477
1478 // Section on thread-local allocation buffers (TLABs)
1479 // See CollectedHeap for semantics.
1480
1481 virtual bool supports_tlab_allocation() const;
1482 virtual size_t tlab_capacity(Thread* thr) const;
1483 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1484
1485 // Can a compiler initialize a new object without store barriers?
1486 // This permission only extends from the creation of a new object
1487 // via a TLAB up to the first subsequent safepoint. If such permission
1488 // is granted for this heap type, the compiler promises to call
1489 // defer_store_barrier() below on any slow path allocation of
1490 // a new object for which such initializing store barriers will
1491 // have been elided. G1, like CMS, allows this, but should be
1492 // ready to provide a compensating write barrier as necessary
1493 // if that storage came out of a non-young region. The efficiency
1494 // of this implementation depends crucially on being able to
1495 // answer very efficiently in constant time whether a piece of
1496 // storage in the heap comes from a young region or not.
1497 // See ReduceInitialCardMarks.
1498 virtual bool can_elide_tlab_store_barriers() const {
1499 return true;
1500 }
1501
1502 virtual bool card_mark_must_follow_store() const {
1503 return true;
1504 }
1505
1506 bool is_in_young(const oop obj) {
1507 HeapRegion* hr = heap_region_containing(obj);
1508 return hr != NULL && hr->is_young();
1509 }
1510
1511 #ifdef ASSERT
1512 virtual bool is_in_partial_collection(const void* p);
1513 #endif
1514
1515 virtual bool is_scavengable(const void* addr);
1516
1517 // We don't need barriers for initializing stores to objects
1518 // in the young gen: for the SATB pre-barrier, there is no
1519 // pre-value that needs to be remembered; for the remembered-set
1520 // update logging post-barrier, we don't maintain remembered set
1521 // information for young gen objects.
1522 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1523 return is_in_young(new_obj);
1524 }
1525
1526 // Returns "true" iff the given word_size is "very large".
1527 static bool isHumongous(size_t word_size) {
1528 // Note this has to be strictly greater-than as the TLABs
1529 // are capped at the humongous thresold and we want to
1530 // ensure that we don't try to allocate a TLAB as
1531 // humongous and that we don't allocate a humongous
1532 // object in a TLAB.
1533 return word_size > _humongous_object_threshold_in_words;
1534 }
1535
1536 // Update mod union table with the set of dirty cards.
1537 void updateModUnion();
1538
1539 // Set the mod union bits corresponding to the given memRegion. Note
1540 // that this is always a safe operation, since it doesn't clear any
1541 // bits.
1542 void markModUnionRange(MemRegion mr);
1543
1544 // Records the fact that a marking phase is no longer in progress.
1545 void set_marking_complete() {
1546 _mark_in_progress = false;
1547 }
1548 void set_marking_started() {
1549 _mark_in_progress = true;
1550 }
1551 bool mark_in_progress() {
1552 return _mark_in_progress;
1553 }
1554
1555 // Print the maximum heap capacity.
1556 virtual size_t max_capacity() const;
1557
1558 virtual jlong millis_since_last_gc();
1559
1560
1561 // Convenience function to be used in situations where the heap type can be
1562 // asserted to be this type.
1563 static G1CollectedHeap* heap();
1564
1565 void set_region_short_lived_locked(HeapRegion* hr);
1566 // add appropriate methods for any other surv rate groups
1567
1568 YoungList* young_list() { return _young_list; }
1569
1570 // debugging
1571 bool check_young_list_well_formed() {
1572 return _young_list->check_list_well_formed();
1573 }
1574
1575 bool check_young_list_empty(bool check_heap,
1576 bool check_sample = true);
1577
1578 // *** Stuff related to concurrent marking. It's not clear to me that so
1579 // many of these need to be public.
1580
1581 // The functions below are helper functions that a subclass of
1582 // "CollectedHeap" can use in the implementation of its virtual
1583 // functions.
1584 // This performs a concurrent marking of the live objects in a
1585 // bitmap off to the side.
1586 void doConcurrentMark();
1587
1588 bool isMarkedPrev(oop obj) const;
1589 bool isMarkedNext(oop obj) const;
1590
1591 // Determine if an object is dead, given the object and also
1592 // the region to which the object belongs. An object is dead
1593 // iff a) it was not allocated since the last mark and b) it
1594 // is not marked.
1595
1596 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1597 return
1598 !hr->obj_allocated_since_prev_marking(obj) &&
1599 !isMarkedPrev(obj);
1600 }
1601
1602 // This function returns true when an object has been
1603 // around since the previous marking and hasn't yet
1604 // been marked during this marking.
1605
1606 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1607 return
1608 !hr->obj_allocated_since_next_marking(obj) &&
1609 !isMarkedNext(obj);
1610 }
1611
1612 // Determine if an object is dead, given only the object itself.
1613 // This will find the region to which the object belongs and
1614 // then call the region version of the same function.
1615
1616 // Added if it is NULL it isn't dead.
1617
1618 bool is_obj_dead(const oop obj) const {
1619 const HeapRegion* hr = heap_region_containing(obj);
1620 if (hr == NULL) {
1621 if (obj == NULL) return false;
1622 else return true;
1623 }
1624 else return is_obj_dead(obj, hr);
1625 }
1626
1627 bool is_obj_ill(const oop obj) const {
1628 const HeapRegion* hr = heap_region_containing(obj);
1629 if (hr == NULL) {
1630 if (obj == NULL) return false;
1631 else return true;
1632 }
1633 else return is_obj_ill(obj, hr);
1634 }
1635
1636 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1637 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1638 bool is_marked(oop obj, VerifyOption vo);
1639 const char* top_at_mark_start_str(VerifyOption vo);
1640
1641 ConcurrentMark* concurrent_mark() const { return _cm; }
1642
1643 // Refinement
1644
1645 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1646
1647 // The dirty cards region list is used to record a subset of regions
1648 // whose cards need clearing. The list if populated during the
1649 // remembered set scanning and drained during the card table
1650 // cleanup. Although the methods are reentrant, population/draining
1651 // phases must not overlap. For synchronization purposes the last
1652 // element on the list points to itself.
1653 HeapRegion* _dirty_cards_region_list;
1654 void push_dirty_cards_region(HeapRegion* hr);
1655 HeapRegion* pop_dirty_cards_region();
1656
1657 // Optimized nmethod scanning support routines
1658
1659 // Register the given nmethod with the G1 heap
1660 virtual void register_nmethod(nmethod* nm);
1661
1662 // Unregister the given nmethod from the G1 heap
1663 virtual void unregister_nmethod(nmethod* nm);
1664
1665 // Migrate the nmethods in the code root lists of the regions
1666 // in the collection set to regions in to-space. In the event
1667 // of an evacuation failure, nmethods that reference objects
1668 // that were not successfullly evacuated are not migrated.
1669 void migrate_strong_code_roots();
1670
1671 // During an initial mark pause, mark all the code roots that
1672 // point into regions *not* in the collection set.
1673 void mark_strong_code_roots(uint worker_id);
1674
1675 // Rebuild the stong code root lists for each region
1676 // after a full GC
1677 void rebuild_strong_code_roots();
1678
1679 // Verification
1680
1681 // The following is just to alert the verification code
1682 // that a full collection has occurred and that the
1683 // remembered sets are no longer up to date.
1684 bool _full_collection;
1685 void set_full_collection() { _full_collection = true;}
1686 void clear_full_collection() {_full_collection = false;}
1687 bool full_collection() {return _full_collection;}
1688
1689 // Perform any cleanup actions necessary before allowing a verification.
1690 virtual void prepare_for_verify();
1691
1692 // Perform verification.
1693
1694 // vo == UsePrevMarking -> use "prev" marking information,
1695 // vo == UseNextMarking -> use "next" marking information
1696 // vo == UseMarkWord -> use the mark word in the object header
1697 //
1698 // NOTE: Only the "prev" marking information is guaranteed to be
1699 // consistent most of the time, so most calls to this should use
1700 // vo == UsePrevMarking.
1701 // Currently, there is only one case where this is called with
1702 // vo == UseNextMarking, which is to verify the "next" marking
1703 // information at the end of remark.
1704 // Currently there is only one place where this is called with
1705 // vo == UseMarkWord, which is to verify the marking during a
1706 // full GC.
1707 void verify(bool silent, VerifyOption vo);
1708
1709 // Override; it uses the "prev" marking information
1710 virtual void verify(bool silent);
1711
1712 // The methods below are here for convenience and dispatch the
1713 // appropriate method depending on value of the given VerifyOption
1714 // parameter. The values for that parameter, and their meanings,
1715 // are the same as those above.
1716
1717 bool is_obj_dead_cond(const oop obj,
1718 const HeapRegion* hr,
1719 const VerifyOption vo) const {
1720 switch (vo) {
1721 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1722 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1723 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1724 default: ShouldNotReachHere();
1725 }
1726 return false; // keep some compilers happy
1727 }
1728
1729 bool is_obj_dead_cond(const oop obj,
1730 const VerifyOption vo) const {
1731 switch (vo) {
1732 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1733 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1734 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1735 default: ShouldNotReachHere();
1736 }
1737 return false; // keep some compilers happy
1738 }
1739
1740 // Printing
1741
1742 virtual void print_on(outputStream* st) const;
1743 virtual void print_extended_on(outputStream* st) const;
1744 virtual void print_on_error(outputStream* st) const;
1745
1746 virtual void print_gc_threads_on(outputStream* st) const;
1747 virtual void gc_threads_do(ThreadClosure* tc) const;
1748
1749 // Override
1750 void print_tracing_info() const;
1751
1752 // The following two methods are helpful for debugging RSet issues.
1753 void print_cset_rsets() PRODUCT_RETURN;
1754 void print_all_rsets() PRODUCT_RETURN;
1755
1756 public:
1757 void stop_conc_gc_threads();
1758
1759 size_t pending_card_num();
1760 size_t cards_scanned();
1761
1762 protected:
1763 size_t _max_heap_capacity;
1764 };
1765
1766 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1767 private:
1768 bool _retired;
1769
1770 public:
1771 G1ParGCAllocBuffer(size_t gclab_word_size);
1772
1773 void set_buf(HeapWord* buf) {
1774 ParGCAllocBuffer::set_buf(buf);
1775 _retired = false;
1776 }
1777
1778 void retire(bool end_of_gc, bool retain) {
1779 if (_retired)
1780 return;
1781 ParGCAllocBuffer::retire(end_of_gc, retain);
1782 _retired = true;
1783 }
1784
1785 bool is_retired() {
1786 return _retired;
1787 }
1788 };
1789
1790 class G1ParGCAllocBufferContainer {
1791 protected:
1792 static int const _priority_max = 2;
1793 G1ParGCAllocBuffer* _priority_buffer[_priority_max];
1794
1795 public:
1796 G1ParGCAllocBufferContainer(size_t gclab_word_size) {
1797 for (int pr = 0; pr < _priority_max; ++pr) {
1798 _priority_buffer[pr] = new G1ParGCAllocBuffer(gclab_word_size);
1799 }
1800 }
1801
1802 ~G1ParGCAllocBufferContainer() {
1803 for (int pr = 0; pr < _priority_max; ++pr) {
1804 assert(_priority_buffer[pr]->is_retired(), "alloc buffers should all retire at this point.");
1805 delete _priority_buffer[pr];
1806 }
1807 }
1808
1809 HeapWord* allocate(size_t word_sz) {
1810 HeapWord* obj;
1811 for (int pr = 0; pr < _priority_max; ++pr) {
1812 obj = _priority_buffer[pr]->allocate(word_sz);
1813 if (obj != NULL) return obj;
1814 }
1815 return obj;
1816 }
1817
1818 bool contains(void* addr) {
1819 for (int pr = 0; pr < _priority_max; ++pr) {
1820 if (_priority_buffer[pr]->contains(addr)) return true;
1821 }
1822 return false;
1823 }
1824
1825 void undo_allocation(HeapWord* obj, size_t word_sz) {
1826 bool finish_undo;
1827 for (int pr = 0; pr < _priority_max; ++pr) {
1828 if (_priority_buffer[pr]->contains(obj)) {
1829 _priority_buffer[pr]->undo_allocation(obj, word_sz);
1830 finish_undo = true;
1831 }
1832 }
1833 if (!finish_undo) ShouldNotReachHere();
1834 }
1835
1836 size_t words_remaining() {
1837 size_t result = 0;
1838 for (int pr = 0; pr < _priority_max; ++pr) {
1839 result += _priority_buffer[pr]->words_remaining();
1840 }
1841 return result;
1842 }
1843
1844 size_t words_remaining_in_retired_buffer() {
1845 G1ParGCAllocBuffer* retired = _priority_buffer[0];
1846 return retired->words_remaining();
1847 }
1848
1849 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) {
1850 for (int pr = 0; pr < _priority_max; ++pr) {
1851 _priority_buffer[pr]->flush_stats_and_retire(stats, end_of_gc, retain);
1852 }
1853 }
1854
1855 void update(bool end_of_gc, bool retain, HeapWord* buf, size_t word_sz) {
1856 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0];
1857 retired_and_set->retire(end_of_gc, retain);
1858 retired_and_set->set_buf(buf);
1859 retired_and_set->set_word_size(word_sz);
1860 adjust_priority_order();
1861 }
1862
1863 private:
1864 void adjust_priority_order() {
1865 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0];
1866
1867 int last = _priority_max - 1;
1868 for (int pr = 0; pr < last; ++pr) {
1869 _priority_buffer[pr] = _priority_buffer[pr + 1];
1870 }
1871 _priority_buffer[last] = retired_and_set;
1872 }
1873 };
1874
1875 class G1ParScanThreadState : public StackObj {
1876 protected:
1877 G1CollectedHeap* _g1h;
1878 RefToScanQueue* _refs;
1879 DirtyCardQueue _dcq;
1880 G1SATBCardTableModRefBS* _ct_bs;
1881 G1RemSet* _g1_rem;
1882
1883 G1ParGCAllocBufferContainer _surviving_alloc_buffer;
1884 G1ParGCAllocBufferContainer _tenured_alloc_buffer;
1885 G1ParGCAllocBufferContainer* _alloc_buffers[GCAllocPurposeCount];
1886 ageTable _age_table;
1887
1888 size_t _alloc_buffer_waste;
1889 size_t _undo_waste;
1890
1891 OopsInHeapRegionClosure* _evac_failure_cl;
1892 G1ParScanHeapEvacClosure* _evac_cl;
1893 G1ParScanPartialArrayClosure* _partial_scan_cl;
1894
1895 int _hash_seed;
1896 uint _queue_num;
1897
1898 size_t _term_attempts;
1899
1900 double _start;
1901 double _start_strong_roots;
1902 double _strong_roots_time;
1903 double _start_term;
1904 double _term_time;
1905
1906 // Map from young-age-index (0 == not young, 1 is youngest) to
1907 // surviving words. base is what we get back from the malloc call
1908 size_t* _surviving_young_words_base;
1909 // this points into the array, as we use the first few entries for padding
1910 size_t* _surviving_young_words;
1911
1912 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1913
1914 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1915
1916 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1917
1918 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1919 G1SATBCardTableModRefBS* ctbs() { return _ct_bs; }
1920
1921 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1922 if (!from->is_survivor()) {
1923 _g1_rem->par_write_ref(from, p, tid);
1924 }
1925 }
1926
1927 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1928 // If the new value of the field points to the same region or
1929 // is the to-space, we don't need to include it in the Rset updates.
1930 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1931 size_t card_index = ctbs()->index_for(p);
1932 // If the card hasn't been added to the buffer, do it.
1933 if (ctbs()->mark_card_deferred(card_index)) {
1934 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1935 }
1936 }
1937 }
1938
1939 public:
1940 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1941
1942 ~G1ParScanThreadState() {
1943 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1944 }
1945
1946 RefToScanQueue* refs() { return _refs; }
1947 ageTable* age_table() { return &_age_table; }
1948
1949 G1ParGCAllocBufferContainer* alloc_buffer(GCAllocPurpose purpose) {
1950 return _alloc_buffers[purpose];
1951 }
1952
1953 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1954 size_t undo_waste() const { return _undo_waste; }
1955
1956 #ifdef ASSERT
1957 bool verify_ref(narrowOop* ref) const;
1958 bool verify_ref(oop* ref) const;
1959 bool verify_task(StarTask ref) const;
1960 #endif // ASSERT
1961
1962 template <class T> void push_on_queue(T* ref) {
1963 assert(verify_ref(ref), "sanity");
1964 refs()->push(ref);
1965 }
1966
1967 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1968 if (G1DeferredRSUpdate) {
1969 deferred_rs_update(from, p, tid);
1970 } else {
1971 immediate_rs_update(from, p, tid);
1972 }
1973 }
1974
1975 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1976 HeapWord* obj = NULL;
1977 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1978 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1979 G1ParGCAllocBufferContainer* alloc_buf = alloc_buffer(purpose);
1980
1981 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1982 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1983
1984 add_to_alloc_buffer_waste(alloc_buf->words_remaining_in_retired_buffer());
1985 alloc_buf->update(false /* end_of_gc */, false /* retain */, buf, gclab_word_size);
1986
1987 obj = alloc_buf->allocate(word_sz);
1988 assert(obj != NULL, "buffer was definitely big enough...");
1989 } else {
1990 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1991 }
1992 return obj;
1993 }
1994
1995 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1996 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1997 if (obj != NULL) return obj;
1998 return allocate_slow(purpose, word_sz);
1999 }
2000
2001 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
2002 if (alloc_buffer(purpose)->contains(obj)) {
2003 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2004 "should contain whole object");
2005 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2006 } else {
2007 CollectedHeap::fill_with_object(obj, word_sz);
2008 add_to_undo_waste(word_sz);
2009 }
2010 }
2011
2012 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2013 _evac_failure_cl = evac_failure_cl;
2014 }
2015 OopsInHeapRegionClosure* evac_failure_closure() {
2016 return _evac_failure_cl;
2017 }
2018
2019 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2020 _evac_cl = evac_cl;
2021 }
2022
2023 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2024 _partial_scan_cl = partial_scan_cl;
2025 }
2026
2027 int* hash_seed() { return &_hash_seed; }
2028 uint queue_num() { return _queue_num; }
2029
2030 size_t term_attempts() const { return _term_attempts; }
2031 void note_term_attempt() { _term_attempts++; }
2032
2033 void start_strong_roots() {
2034 _start_strong_roots = os::elapsedTime();
2035 }
2036 void end_strong_roots() {
2037 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2038 }
2039 double strong_roots_time() const { return _strong_roots_time; }
2040
2041 void start_term_time() {
2042 note_term_attempt();
2043 _start_term = os::elapsedTime();
2044 }
2045 void end_term_time() {
2046 _term_time += (os::elapsedTime() - _start_term);
2047 }
2048 double term_time() const { return _term_time; }
2049
2050 double elapsed_time() const {
2051 return os::elapsedTime() - _start;
2052 }
2053
2054 static void
2055 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2056 void
2057 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2058
2059 size_t* surviving_young_words() {
2060 // We add on to hide entry 0 which accumulates surviving words for
2061 // age -1 regions (i.e. non-young ones)
2062 return _surviving_young_words;
2063 }
2064
2065 void retire_alloc_buffers() {
2066 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2067 size_t waste = _alloc_buffers[ap]->words_remaining();
2068 add_to_alloc_buffer_waste(waste);
2069 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
2070 true /* end_of_gc */,
2071 false /* retain */);
2072 }
2073 }
2074
2075 template <class T> void deal_with_reference(T* ref_to_scan) {
2076 if (has_partial_array_mask(ref_to_scan)) {
2077 _partial_scan_cl->do_oop_nv(ref_to_scan);
2078 } else {
2079 // Note: we can use "raw" versions of "region_containing" because
2080 // "obj_to_scan" is definitely in the heap, and is not in a
2081 // humongous region.
2082 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2083 _evac_cl->set_region(r);
2084 _evac_cl->do_oop_nv(ref_to_scan);
2085 }
2086 }
2087
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 }
2096
2097 void trim_queue();
2098 };
2099
2100 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP