1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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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 class Ticks;
76
77 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
78 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
79
80 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
81 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
82
83 enum GCAllocPurpose {
84 GCAllocForTenured,
85 GCAllocForSurvived,
86 GCAllocPurposeCount
87 };
88
89 class YoungList : public CHeapObj<mtGC> {
90 private:
91 G1CollectedHeap* _g1h;
92
93 HeapRegion* _head;
94
95 HeapRegion* _survivor_head;
96 HeapRegion* _survivor_tail;
97
98 HeapRegion* _curr;
99
100 uint _length;
101 uint _survivor_length;
102
103 size_t _last_sampled_rs_lengths;
104 size_t _sampled_rs_lengths;
105
106 void empty_list(HeapRegion* list);
107
108 public:
109 YoungList(G1CollectedHeap* g1h);
110
111 void push_region(HeapRegion* hr);
112 void add_survivor_region(HeapRegion* hr);
113
114 void empty_list();
115 bool is_empty() { return _length == 0; }
116 uint length() { return _length; }
117 uint survivor_length() { return _survivor_length; }
118
119 // Currently we do not keep track of the used byte sum for the
120 // young list and the survivors and it'd be quite a lot of work to
121 // do so. When we'll eventually replace the young list with
122 // instances of HeapRegionLinkedList we'll get that for free. So,
123 // we'll report the more accurate information then.
124 size_t eden_used_bytes() {
125 assert(length() >= survivor_length(), "invariant");
126 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
127 }
128 size_t survivor_used_bytes() {
129 return (size_t) survivor_length() * HeapRegion::GrainBytes;
130 }
131
132 void rs_length_sampling_init();
133 bool rs_length_sampling_more();
134 void rs_length_sampling_next();
135
136 void reset_sampled_info() {
137 _last_sampled_rs_lengths = 0;
138 }
139 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
140
141 // for development purposes
142 void reset_auxilary_lists();
143 void clear() { _head = NULL; _length = 0; }
144
145 void clear_survivors() {
146 _survivor_head = NULL;
147 _survivor_tail = NULL;
148 _survivor_length = 0;
149 }
150
151 HeapRegion* first_region() { return _head; }
152 HeapRegion* first_survivor_region() { return _survivor_head; }
153 HeapRegion* last_survivor_region() { return _survivor_tail; }
154
155 // debugging
156 bool check_list_well_formed();
157 bool check_list_empty(bool check_sample = true);
158 void print();
159 };
160
161 class MutatorAllocRegion : public G1AllocRegion {
162 protected:
163 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
164 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
165 public:
166 MutatorAllocRegion()
167 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
168 };
169
170 class SurvivorGCAllocRegion : public G1AllocRegion {
171 protected:
172 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
173 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
174 public:
175 SurvivorGCAllocRegion()
176 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
177 };
178
179 class OldGCAllocRegion : public G1AllocRegion {
180 protected:
181 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
182 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
183 public:
184 OldGCAllocRegion()
185 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
186 };
187
188 // The G1 STW is alive closure.
189 // An instance is embedded into the G1CH and used as the
190 // (optional) _is_alive_non_header closure in the STW
191 // reference processor. It is also extensively used during
192 // reference processing during STW evacuation pauses.
193 class G1STWIsAliveClosure: public BoolObjectClosure {
194 G1CollectedHeap* _g1;
195 public:
196 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
197 bool do_object_b(oop p);
198 };
199
200 class RefineCardTableEntryClosure;
201
202 class G1CollectedHeap : public SharedHeap {
203 friend class VM_G1CollectForAllocation;
204 friend class VM_G1CollectFull;
205 friend class VM_G1IncCollectionPause;
206 friend class VMStructs;
207 friend class MutatorAllocRegion;
208 friend class SurvivorGCAllocRegion;
209 friend class OldGCAllocRegion;
210
211 // Closures used in implementation.
212 template <G1Barrier barrier, bool do_mark_object>
213 friend class G1ParCopyClosure;
214 friend class G1IsAliveClosure;
215 friend class G1EvacuateFollowersClosure;
216 friend class G1ParScanThreadState;
217 friend class G1ParScanClosureSuper;
218 friend class G1ParEvacuateFollowersClosure;
219 friend class G1ParTask;
220 friend class G1FreeGarbageRegionClosure;
221 friend class RefineCardTableEntryClosure;
222 friend class G1PrepareCompactClosure;
223 friend class RegionSorter;
224 friend class RegionResetter;
225 friend class CountRCClosure;
226 friend class EvacPopObjClosure;
227 friend class G1ParCleanupCTTask;
228
229 // Other related classes.
230 friend class G1MarkSweep;
231
232 private:
233 // The one and only G1CollectedHeap, so static functions can find it.
234 static G1CollectedHeap* _g1h;
235
236 static size_t _humongous_object_threshold_in_words;
237
238 // Storage for the G1 heap.
239 VirtualSpace _g1_storage;
240 MemRegion _g1_reserved;
241
242 // The part of _g1_storage that is currently committed.
243 MemRegion _g1_committed;
244
245 // The master free list. It will satisfy all new region allocations.
246 MasterFreeRegionList _free_list;
247
248 // The secondary free list which contains regions that have been
249 // freed up during the cleanup process. This will be appended to the
250 // master free list when appropriate.
251 SecondaryFreeRegionList _secondary_free_list;
252
253 // It keeps track of the old regions.
254 MasterOldRegionSet _old_set;
255
256 // It keeps track of the humongous regions.
257 MasterHumongousRegionSet _humongous_set;
258
259 // The number of regions we could create by expansion.
260 uint _expansion_regions;
261
262 // The block offset table for the G1 heap.
263 G1BlockOffsetSharedArray* _bot_shared;
264
265 // Tears down the region sets / lists so that they are empty and the
266 // regions on the heap do not belong to a region set / list. The
267 // only exception is the humongous set which we leave unaltered. If
268 // free_list_only is true, it will only tear down the master free
269 // list. It is called before a Full GC (free_list_only == false) or
270 // before heap shrinking (free_list_only == true).
271 void tear_down_region_sets(bool free_list_only);
272
273 // Rebuilds the region sets / lists so that they are repopulated to
274 // reflect the contents of the heap. The only exception is the
275 // humongous set which was not torn down in the first place. If
276 // free_list_only is true, it will only rebuild the master free
277 // list. It is called after a Full GC (free_list_only == false) or
278 // after heap shrinking (free_list_only == true).
279 void rebuild_region_sets(bool free_list_only);
280
281 // The sequence of all heap regions in the heap.
282 HeapRegionSeq _hrs;
283
284 // Alloc region used to satisfy mutator allocation requests.
285 MutatorAllocRegion _mutator_alloc_region;
286
287 // Alloc region used to satisfy allocation requests by the GC for
288 // survivor objects.
289 SurvivorGCAllocRegion _survivor_gc_alloc_region;
290
291 // PLAB sizing policy for survivors.
292 PLABStats _survivor_plab_stats;
293
294 // Alloc region used to satisfy allocation requests by the GC for
295 // old objects.
296 OldGCAllocRegion _old_gc_alloc_region;
297
298 // PLAB sizing policy for tenured objects.
299 PLABStats _old_plab_stats;
300
301 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
302 PLABStats* stats = NULL;
303
304 switch (purpose) {
305 case GCAllocForSurvived:
306 stats = &_survivor_plab_stats;
307 break;
308 case GCAllocForTenured:
309 stats = &_old_plab_stats;
310 break;
311 default:
312 assert(false, "unrecognized GCAllocPurpose");
313 }
314
315 return stats;
316 }
317
318 // The last old region we allocated to during the last GC.
319 // Typically, it is not full so we should re-use it during the next GC.
320 HeapRegion* _retained_old_gc_alloc_region;
321
322 // It specifies whether we should attempt to expand the heap after a
323 // region allocation failure. If heap expansion fails we set this to
324 // false so that we don't re-attempt the heap expansion (it's likely
325 // that subsequent expansion attempts will also fail if one fails).
326 // Currently, it is only consulted during GC and it's reset at the
327 // start of each GC.
328 bool _expand_heap_after_alloc_failure;
329
330 // It resets the mutator alloc region before new allocations can take place.
331 void init_mutator_alloc_region();
332
333 // It releases the mutator alloc region.
334 void release_mutator_alloc_region();
335
336 // It initializes the GC alloc regions at the start of a GC.
337 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
338
339 // It releases the GC alloc regions at the end of a GC.
340 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
341
342 // It does any cleanup that needs to be done on the GC alloc regions
343 // before a Full GC.
344 void abandon_gc_alloc_regions();
345
346 // Helper for monitoring and management support.
347 G1MonitoringSupport* _g1mm;
348
349 // Determines PLAB size for a particular allocation purpose.
350 size_t desired_plab_sz(GCAllocPurpose purpose);
351
352 // Outside of GC pauses, the number of bytes used in all regions other
353 // than the current allocation region.
354 size_t _summary_bytes_used;
355
356 // This is used for a quick test on whether a reference points into
357 // the collection set or not. Basically, we have an array, with one
358 // byte per region, and that byte denotes whether the corresponding
359 // region is in the collection set or not. The entry corresponding
360 // the bottom of the heap, i.e., region 0, is pointed to by
361 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
362 // biased so that it actually points to address 0 of the address
363 // space, to make the test as fast as possible (we can simply shift
364 // the address to address into it, instead of having to subtract the
365 // bottom of the heap from the address before shifting it; basically
366 // it works in the same way the card table works).
367 bool* _in_cset_fast_test;
368
369 // The allocated array used for the fast test on whether a reference
370 // points into the collection set or not. This field is also used to
371 // free the array.
372 bool* _in_cset_fast_test_base;
373
374 // The length of the _in_cset_fast_test_base array.
375 uint _in_cset_fast_test_length;
376
377 volatile unsigned _gc_time_stamp;
378
379 size_t* _surviving_young_words;
380
381 G1HRPrinter _hr_printer;
382
383 void setup_surviving_young_words();
384 void update_surviving_young_words(size_t* surv_young_words);
385 void cleanup_surviving_young_words();
386
387 // It decides whether an explicit GC should start a concurrent cycle
388 // instead of doing a STW GC. Currently, a concurrent cycle is
389 // explicitly started if:
390 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
391 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
392 // (c) cause == _g1_humongous_allocation
393 bool should_do_concurrent_full_gc(GCCause::Cause cause);
394
395 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
396 // concurrent cycles) we have started.
397 volatile unsigned int _old_marking_cycles_started;
398
399 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
400 // concurrent cycles) we have completed.
401 volatile unsigned int _old_marking_cycles_completed;
402
403 bool _concurrent_cycle_started;
404
405 // This is a non-product method that is helpful for testing. It is
406 // called at the end of a GC and artificially expands the heap by
407 // allocating a number of dead regions. This way we can induce very
408 // frequent marking cycles and stress the cleanup / concurrent
409 // cleanup code more (as all the regions that will be allocated by
410 // this method will be found dead by the marking cycle).
411 void allocate_dummy_regions() PRODUCT_RETURN;
412
413 // Clear RSets after a compaction. It also resets the GC time stamps.
414 void clear_rsets_post_compaction();
415
416 // If the HR printer is active, dump the state of the regions in the
417 // heap after a compaction.
418 void print_hrs_post_compaction();
419
420 double verify(bool guard, const char* msg);
421 void verify_before_gc();
422 void verify_after_gc();
423
424 void log_gc_header();
425 void log_gc_footer(double pause_time_sec);
426
427 // These are macros so that, if the assert fires, we get the correct
428 // line number, file, etc.
429
430 #define heap_locking_asserts_err_msg(_extra_message_) \
431 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
432 (_extra_message_), \
433 BOOL_TO_STR(Heap_lock->owned_by_self()), \
434 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
435 BOOL_TO_STR(Thread::current()->is_VM_thread()))
436
437 #define assert_heap_locked() \
438 do { \
439 assert(Heap_lock->owned_by_self(), \
440 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
441 } while (0)
442
443 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
444 do { \
445 assert(Heap_lock->owned_by_self() || \
446 (SafepointSynchronize::is_at_safepoint() && \
447 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
448 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
449 "should be at a safepoint")); \
450 } while (0)
451
452 #define assert_heap_locked_and_not_at_safepoint() \
453 do { \
454 assert(Heap_lock->owned_by_self() && \
455 !SafepointSynchronize::is_at_safepoint(), \
456 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
457 "should not be at a safepoint")); \
458 } while (0)
459
460 #define assert_heap_not_locked() \
461 do { \
462 assert(!Heap_lock->owned_by_self(), \
463 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
464 } while (0)
465
466 #define assert_heap_not_locked_and_not_at_safepoint() \
467 do { \
468 assert(!Heap_lock->owned_by_self() && \
469 !SafepointSynchronize::is_at_safepoint(), \
470 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
471 "should not be at a safepoint")); \
472 } while (0)
473
474 #define assert_at_safepoint(_should_be_vm_thread_) \
475 do { \
476 assert(SafepointSynchronize::is_at_safepoint() && \
477 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
478 heap_locking_asserts_err_msg("should be at a safepoint")); \
479 } while (0)
480
481 #define assert_not_at_safepoint() \
482 do { \
483 assert(!SafepointSynchronize::is_at_safepoint(), \
484 heap_locking_asserts_err_msg("should not be at a safepoint")); \
485 } while (0)
486
487 protected:
488
489 // The young region list.
490 YoungList* _young_list;
491
492 // The current policy object for the collector.
493 G1CollectorPolicy* _g1_policy;
494
495 // This is the second level of trying to allocate a new region. If
496 // new_region() didn't find a region on the free_list, this call will
497 // check whether there's anything available on the
498 // secondary_free_list and/or wait for more regions to appear on
499 // that list, if _free_regions_coming is set.
500 HeapRegion* new_region_try_secondary_free_list();
501
502 // Try to allocate a single non-humongous HeapRegion sufficient for
503 // an allocation of the given word_size. If do_expand is true,
504 // attempt to expand the heap if necessary to satisfy the allocation
505 // request.
506 HeapRegion* new_region(size_t word_size, bool do_expand);
507
508 // Attempt to satisfy a humongous allocation request of the given
509 // size by finding a contiguous set of free regions of num_regions
510 // length and remove them from the master free list. Return the
511 // index of the first region or G1_NULL_HRS_INDEX if the search
512 // was unsuccessful.
513 uint humongous_obj_allocate_find_first(uint num_regions,
514 size_t word_size);
515
516 // Initialize a contiguous set of free regions of length num_regions
517 // and starting at index first so that they appear as a single
518 // humongous region.
519 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
520 uint num_regions,
521 size_t word_size);
522
523 // Attempt to allocate a humongous object of the given size. Return
524 // NULL if unsuccessful.
525 HeapWord* humongous_obj_allocate(size_t word_size);
526
527 // The following two methods, allocate_new_tlab() and
528 // mem_allocate(), are the two main entry points from the runtime
529 // into the G1's allocation routines. They have the following
530 // assumptions:
531 //
532 // * They should both be called outside safepoints.
533 //
534 // * They should both be called without holding the Heap_lock.
535 //
536 // * All allocation requests for new TLABs should go to
537 // allocate_new_tlab().
538 //
539 // * All non-TLAB allocation requests should go to mem_allocate().
540 //
541 // * If either call cannot satisfy the allocation request using the
542 // current allocating region, they will try to get a new one. If
543 // this fails, they will attempt to do an evacuation pause and
544 // retry the allocation.
545 //
546 // * If all allocation attempts fail, even after trying to schedule
547 // an evacuation pause, allocate_new_tlab() will return NULL,
548 // whereas mem_allocate() will attempt a heap expansion and/or
549 // schedule a Full GC.
550 //
551 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
552 // should never be called with word_size being humongous. All
553 // humongous allocation requests should go to mem_allocate() which
554 // will satisfy them with a special path.
555
556 virtual HeapWord* allocate_new_tlab(size_t word_size);
557
558 virtual HeapWord* mem_allocate(size_t word_size,
559 bool* gc_overhead_limit_was_exceeded);
560
561 // The following three methods take a gc_count_before_ret
562 // parameter which is used to return the GC count if the method
563 // returns NULL. Given that we are required to read the GC count
564 // while holding the Heap_lock, and these paths will take the
565 // Heap_lock at some point, it's easier to get them to read the GC
566 // count while holding the Heap_lock before they return NULL instead
567 // of the caller (namely: mem_allocate()) having to also take the
568 // Heap_lock just to read the GC count.
569
570 // First-level mutator allocation attempt: try to allocate out of
571 // the mutator alloc region without taking the Heap_lock. This
572 // should only be used for non-humongous allocations.
573 inline HeapWord* attempt_allocation(size_t word_size,
574 unsigned int* gc_count_before_ret,
575 int* gclocker_retry_count_ret);
576
577 // Second-level mutator allocation attempt: take the Heap_lock and
578 // retry the allocation attempt, potentially scheduling a GC
579 // pause. This should only be used for non-humongous allocations.
580 HeapWord* attempt_allocation_slow(size_t word_size,
581 unsigned int* gc_count_before_ret,
582 int* gclocker_retry_count_ret);
583
584 // Takes the Heap_lock and attempts a humongous allocation. It can
585 // potentially schedule a GC pause.
586 HeapWord* attempt_allocation_humongous(size_t word_size,
587 unsigned int* gc_count_before_ret,
588 int* gclocker_retry_count_ret);
589
590 // Allocation attempt that should be called during safepoints (e.g.,
591 // at the end of a successful GC). expect_null_mutator_alloc_region
592 // specifies whether the mutator alloc region is expected to be NULL
593 // or not.
594 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
595 bool expect_null_mutator_alloc_region);
596
597 // It dirties the cards that cover the block so that so that the post
598 // write barrier never queues anything when updating objects on this
599 // block. It is assumed (and in fact we assert) that the block
600 // belongs to a young region.
601 inline void dirty_young_block(HeapWord* start, size_t word_size);
602
603 // Allocate blocks during garbage collection. Will ensure an
604 // allocation region, either by picking one or expanding the
605 // heap, and then allocate a block of the given size. The block
606 // may not be a humongous - it must fit into a single heap region.
607 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
608
609 // Ensure that no further allocations can happen in "r", bearing in mind
610 // that parallel threads might be attempting allocations.
611 void par_allocate_remaining_space(HeapRegion* r);
612
613 // Allocation attempt during GC for a survivor object / PLAB.
614 inline HeapWord* survivor_attempt_allocation(size_t word_size);
615
616 // Allocation attempt during GC for an old object / PLAB.
617 inline HeapWord* old_attempt_allocation(size_t word_size);
618
619 // These methods are the "callbacks" from the G1AllocRegion class.
620
621 // For mutator alloc regions.
622 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
623 void retire_mutator_alloc_region(HeapRegion* alloc_region,
624 size_t allocated_bytes);
625
626 // For GC alloc regions.
627 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
628 GCAllocPurpose ap);
629 void retire_gc_alloc_region(HeapRegion* alloc_region,
630 size_t allocated_bytes, GCAllocPurpose ap);
631
632 // - if explicit_gc is true, the GC is for a System.gc() or a heap
633 // inspection request and should collect the entire heap
634 // - if clear_all_soft_refs is true, all soft references should be
635 // cleared during the GC
636 // - if explicit_gc is false, word_size describes the allocation that
637 // the GC should attempt (at least) to satisfy
638 // - it returns false if it is unable to do the collection due to the
639 // GC locker being active, true otherwise
640 bool do_collection(bool explicit_gc,
641 bool clear_all_soft_refs,
642 size_t word_size);
643
644 // Callback from VM_G1CollectFull operation.
645 // Perform a full collection.
646 virtual void do_full_collection(bool clear_all_soft_refs);
647
648 // Resize the heap if necessary after a full collection. If this is
649 // after a collect-for allocation, "word_size" is the allocation size,
650 // and will be considered part of the used portion of the heap.
651 void resize_if_necessary_after_full_collection(size_t word_size);
652
653 // Callback from VM_G1CollectForAllocation operation.
654 // This function does everything necessary/possible to satisfy a
655 // failed allocation request (including collection, expansion, etc.)
656 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
657
658 // Attempting to expand the heap sufficiently
659 // to support an allocation of the given "word_size". If
660 // successful, perform the allocation and return the address of the
661 // allocated block, or else "NULL".
662 HeapWord* expand_and_allocate(size_t word_size);
663
664 // Process any reference objects discovered during
665 // an incremental evacuation pause.
666 void process_discovered_references(uint no_of_gc_workers);
667
668 // Enqueue any remaining discovered references
669 // after processing.
670 void enqueue_discovered_references(uint no_of_gc_workers);
671
672 public:
673
674 G1MonitoringSupport* g1mm() {
675 assert(_g1mm != NULL, "should have been initialized");
676 return _g1mm;
677 }
678
679 // Expand the garbage-first heap by at least the given size (in bytes!).
680 // Returns true if the heap was expanded by the requested amount;
681 // false otherwise.
682 // (Rounds up to a HeapRegion boundary.)
683 bool expand(size_t expand_bytes);
684
685 // Do anything common to GC's.
686 virtual void gc_prologue(bool full);
687 virtual void gc_epilogue(bool full);
688
689 // We register a region with the fast "in collection set" test. We
690 // simply set to true the array slot corresponding to this region.
691 void register_region_with_in_cset_fast_test(HeapRegion* r) {
692 assert(_in_cset_fast_test_base != NULL, "sanity");
693 assert(r->in_collection_set(), "invariant");
694 uint index = r->hrs_index();
695 assert(index < _in_cset_fast_test_length, "invariant");
696 assert(!_in_cset_fast_test_base[index], "invariant");
697 _in_cset_fast_test_base[index] = true;
698 }
699
700 // This is a fast test on whether a reference points into the
701 // collection set or not. It does not assume that the reference
702 // points into the heap; if it doesn't, it will return false.
703 bool in_cset_fast_test(oop obj) {
704 assert(_in_cset_fast_test != NULL, "sanity");
705 if (_g1_committed.contains((HeapWord*) obj)) {
706 // no need to subtract the bottom of the heap from obj,
707 // _in_cset_fast_test is biased
708 uintx index = cast_from_oop<uintx>(obj) >> HeapRegion::LogOfHRGrainBytes;
709 bool ret = _in_cset_fast_test[index];
710 // let's make sure the result is consistent with what the slower
711 // test returns
712 assert( ret || !obj_in_cs(obj), "sanity");
713 assert(!ret || obj_in_cs(obj), "sanity");
714 return ret;
715 } else {
716 return false;
717 }
718 }
719
720 void clear_cset_fast_test() {
721 assert(_in_cset_fast_test_base != NULL, "sanity");
722 memset(_in_cset_fast_test_base, false,
723 (size_t) _in_cset_fast_test_length * sizeof(bool));
724 }
725
726 // This is called at the start of either a concurrent cycle or a Full
727 // GC to update the number of old marking cycles started.
728 void increment_old_marking_cycles_started();
729
730 // This is called at the end of either a concurrent cycle or a Full
731 // GC to update the number of old marking cycles completed. Those two
732 // can happen in a nested fashion, i.e., we start a concurrent
733 // cycle, a Full GC happens half-way through it which ends first,
734 // and then the cycle notices that a Full GC happened and ends
735 // too. The concurrent parameter is a boolean to help us do a bit
736 // tighter consistency checking in the method. If concurrent is
737 // false, the caller is the inner caller in the nesting (i.e., the
738 // Full GC). If concurrent is true, the caller is the outer caller
739 // in this nesting (i.e., the concurrent cycle). Further nesting is
740 // not currently supported. The end of this call also notifies
741 // the FullGCCount_lock in case a Java thread is waiting for a full
742 // GC to happen (e.g., it called System.gc() with
743 // +ExplicitGCInvokesConcurrent).
744 void increment_old_marking_cycles_completed(bool concurrent);
745
746 unsigned int old_marking_cycles_completed() {
747 return _old_marking_cycles_completed;
748 }
749
750 void register_concurrent_cycle_start(const Ticks& start_time);
751 void register_concurrent_cycle_end();
752 void trace_heap_after_concurrent_cycle();
753
754 G1YCType yc_type();
755
756 G1HRPrinter* hr_printer() { return &_hr_printer; }
757
758 protected:
759
760 // Shrink the garbage-first heap by at most the given size (in bytes!).
761 // (Rounds down to a HeapRegion boundary.)
762 virtual void shrink(size_t expand_bytes);
763 void shrink_helper(size_t expand_bytes);
764
765 #if TASKQUEUE_STATS
766 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
767 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
768 void reset_taskqueue_stats();
769 #endif // TASKQUEUE_STATS
770
771 // Schedule the VM operation that will do an evacuation pause to
772 // satisfy an allocation request of word_size. *succeeded will
773 // return whether the VM operation was successful (it did do an
774 // evacuation pause) or not (another thread beat us to it or the GC
775 // locker was active). Given that we should not be holding the
776 // Heap_lock when we enter this method, we will pass the
777 // gc_count_before (i.e., total_collections()) as a parameter since
778 // it has to be read while holding the Heap_lock. Currently, both
779 // methods that call do_collection_pause() release the Heap_lock
780 // before the call, so it's easy to read gc_count_before just before.
781 HeapWord* do_collection_pause(size_t word_size,
782 unsigned int gc_count_before,
783 bool* succeeded,
784 GCCause::Cause gc_cause);
785
786 // The guts of the incremental collection pause, executed by the vm
787 // thread. It returns false if it is unable to do the collection due
788 // to the GC locker being active, true otherwise
789 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
790
791 // Actually do the work of evacuating the collection set.
792 void evacuate_collection_set(EvacuationInfo& evacuation_info);
793
794 // The g1 remembered set of the heap.
795 G1RemSet* _g1_rem_set;
796
797 // A set of cards that cover the objects for which the Rsets should be updated
798 // concurrently after the collection.
799 DirtyCardQueueSet _dirty_card_queue_set;
800
801 // The closure used to refine a single card.
802 RefineCardTableEntryClosure* _refine_cte_cl;
803
804 // A function to check the consistency of dirty card logs.
805 void check_ct_logs_at_safepoint();
806
807 // A DirtyCardQueueSet that is used to hold cards that contain
808 // references into the current collection set. This is used to
809 // update the remembered sets of the regions in the collection
810 // set in the event of an evacuation failure.
811 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
812
813 // After a collection pause, make the regions in the CS into free
814 // regions.
815 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
816
817 // Abandon the current collection set without recording policy
818 // statistics or updating free lists.
819 void abandon_collection_set(HeapRegion* cs_head);
820
821 // Applies "scan_non_heap_roots" to roots outside the heap,
822 // "scan_rs" to roots inside the heap (having done "set_region" to
823 // indicate the region in which the root resides),
824 // and does "scan_metadata" If "scan_rs" is
825 // NULL, then this step is skipped. The "worker_i"
826 // param is for use with parallel roots processing, and should be
827 // the "i" of the calling parallel worker thread's work(i) function.
828 // In the sequential case this param will be ignored.
829 void g1_process_strong_roots(bool is_scavenging,
830 ScanningOption so,
831 OopClosure* scan_non_heap_roots,
832 OopsInHeapRegionClosure* scan_rs,
833 G1KlassScanClosure* scan_klasses,
834 int worker_i);
835
836 // Apply "blk" to all the weak roots of the system. These include
837 // JNI weak roots, the code cache, system dictionary, symbol table,
838 // string table, and referents of reachable weak refs.
839 void g1_process_weak_roots(OopClosure* root_closure);
840
841 // Frees a non-humongous region by initializing its contents and
842 // adding it to the free list that's passed as a parameter (this is
843 // usually a local list which will be appended to the master free
844 // list later). The used bytes of freed regions are accumulated in
845 // pre_used. If par is true, the region's RSet will not be freed
846 // up. The assumption is that this will be done later.
847 // The locked parameter indicates if the caller has already taken
848 // care of proper synchronization. This may allow some optimizations.
849 void free_region(HeapRegion* hr,
850 size_t* pre_used,
851 FreeRegionList* free_list,
852 bool par, bool locked = false);
853
854 // Frees a humongous region by collapsing it into individual regions
855 // and calling free_region() for each of them. The freed regions
856 // will be added to the free list that's passed as a parameter (this
857 // is usually a local list which will be appended to the master free
858 // list later). The used bytes of freed regions are accumulated in
859 // pre_used. If par is true, the region's RSet will not be freed
860 // up. The assumption is that this will be done later.
861 void free_humongous_region(HeapRegion* hr,
862 size_t* pre_used,
863 FreeRegionList* free_list,
864 HumongousRegionSet* humongous_proxy_set,
865 bool par);
866
867 // Notifies all the necessary spaces that the committed space has
868 // been updated (either expanded or shrunk). It should be called
869 // after _g1_storage is updated.
870 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
871
872 // The concurrent marker (and the thread it runs in.)
873 ConcurrentMark* _cm;
874 ConcurrentMarkThread* _cmThread;
875 bool _mark_in_progress;
876
877 // The concurrent refiner.
878 ConcurrentG1Refine* _cg1r;
879
880 // The parallel task queues
881 RefToScanQueueSet *_task_queues;
882
883 // True iff a evacuation has failed in the current collection.
884 bool _evacuation_failed;
885
886 EvacuationFailedInfo* _evacuation_failed_info_array;
887
888 // Failed evacuations cause some logical from-space objects to have
889 // forwarding pointers to themselves. Reset them.
890 void remove_self_forwarding_pointers();
891
892 // Together, these store an object with a preserved mark, and its mark value.
893 Stack<oop, mtGC> _objs_with_preserved_marks;
894 Stack<markOop, mtGC> _preserved_marks_of_objs;
895
896 // Preserve the mark of "obj", if necessary, in preparation for its mark
897 // word being overwritten with a self-forwarding-pointer.
898 void preserve_mark_if_necessary(oop obj, markOop m);
899
900 // The stack of evac-failure objects left to be scanned.
901 GrowableArray<oop>* _evac_failure_scan_stack;
902 // The closure to apply to evac-failure objects.
903
904 OopsInHeapRegionClosure* _evac_failure_closure;
905 // Set the field above.
906 void
907 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
908 _evac_failure_closure = evac_failure_closure;
909 }
910
911 // Push "obj" on the scan stack.
912 void push_on_evac_failure_scan_stack(oop obj);
913 // Process scan stack entries until the stack is empty.
914 void drain_evac_failure_scan_stack();
915 // True iff an invocation of "drain_scan_stack" is in progress; to
916 // prevent unnecessary recursion.
917 bool _drain_in_progress;
918
919 // Do any necessary initialization for evacuation-failure handling.
920 // "cl" is the closure that will be used to process evac-failure
921 // objects.
922 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
923 // Do any necessary cleanup for evacuation-failure handling data
924 // structures.
925 void finalize_for_evac_failure();
926
927 // An attempt to evacuate "obj" has failed; take necessary steps.
928 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
929 void handle_evacuation_failure_common(oop obj, markOop m);
930
931 #ifndef PRODUCT
932 // Support for forcing evacuation failures. Analogous to
933 // PromotionFailureALot for the other collectors.
934
935 // Records whether G1EvacuationFailureALot should be in effect
936 // for the current GC
937 bool _evacuation_failure_alot_for_current_gc;
938
939 // Used to record the GC number for interval checking when
940 // determining whether G1EvaucationFailureALot is in effect
941 // for the current GC.
942 size_t _evacuation_failure_alot_gc_number;
943
944 // Count of the number of evacuations between failures.
945 volatile size_t _evacuation_failure_alot_count;
946
947 // Set whether G1EvacuationFailureALot should be in effect
948 // for the current GC (based upon the type of GC and which
949 // command line flags are set);
950 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
951 bool during_initial_mark,
952 bool during_marking);
953
954 inline void set_evacuation_failure_alot_for_current_gc();
955
956 // Return true if it's time to cause an evacuation failure.
957 inline bool evacuation_should_fail();
958
959 // Reset the G1EvacuationFailureALot counters. Should be called at
960 // the end of an evacuation pause in which an evacuation failure occurred.
961 inline void reset_evacuation_should_fail();
962 #endif // !PRODUCT
963
964 // ("Weak") Reference processing support.
965 //
966 // G1 has 2 instances of the reference processor class. One
967 // (_ref_processor_cm) handles reference object discovery
968 // and subsequent processing during concurrent marking cycles.
969 //
970 // The other (_ref_processor_stw) handles reference object
971 // discovery and processing during full GCs and incremental
972 // evacuation pauses.
973 //
974 // During an incremental pause, reference discovery will be
975 // temporarily disabled for _ref_processor_cm and will be
976 // enabled for _ref_processor_stw. At the end of the evacuation
977 // pause references discovered by _ref_processor_stw will be
978 // processed and discovery will be disabled. The previous
979 // setting for reference object discovery for _ref_processor_cm
980 // will be re-instated.
981 //
982 // At the start of marking:
983 // * Discovery by the CM ref processor is verified to be inactive
984 // and it's discovered lists are empty.
985 // * Discovery by the CM ref processor is then enabled.
986 //
987 // At the end of marking:
988 // * Any references on the CM ref processor's discovered
989 // lists are processed (possibly MT).
990 //
991 // At the start of full GC we:
992 // * Disable discovery by the CM ref processor and
993 // empty CM ref processor's discovered lists
994 // (without processing any entries).
995 // * Verify that the STW ref processor is inactive and it's
996 // discovered lists are empty.
997 // * Temporarily set STW ref processor discovery as single threaded.
998 // * Temporarily clear the STW ref processor's _is_alive_non_header
999 // field.
1000 // * Finally enable discovery by the STW ref processor.
1001 //
1002 // The STW ref processor is used to record any discovered
1003 // references during the full GC.
1004 //
1005 // At the end of a full GC we:
1006 // * Enqueue any reference objects discovered by the STW ref processor
1007 // that have non-live referents. This has the side-effect of
1008 // making the STW ref processor inactive by disabling discovery.
1009 // * Verify that the CM ref processor is still inactive
1010 // and no references have been placed on it's discovered
1011 // lists (also checked as a precondition during initial marking).
1012
1013 // The (stw) reference processor...
1014 ReferenceProcessor* _ref_processor_stw;
1015
1016 STWGCTimer* _gc_timer_stw;
1017 ConcurrentGCTimer* _gc_timer_cm;
1018
1019 G1OldTracer* _gc_tracer_cm;
1020 G1NewTracer* _gc_tracer_stw;
1021
1022 // During reference object discovery, the _is_alive_non_header
1023 // closure (if non-null) is applied to the referent object to
1024 // determine whether the referent is live. If so then the
1025 // reference object does not need to be 'discovered' and can
1026 // be treated as a regular oop. This has the benefit of reducing
1027 // the number of 'discovered' reference objects that need to
1028 // be processed.
1029 //
1030 // Instance of the is_alive closure for embedding into the
1031 // STW reference processor as the _is_alive_non_header field.
1032 // Supplying a value for the _is_alive_non_header field is
1033 // optional but doing so prevents unnecessary additions to
1034 // the discovered lists during reference discovery.
1035 G1STWIsAliveClosure _is_alive_closure_stw;
1036
1037 // The (concurrent marking) reference processor...
1038 ReferenceProcessor* _ref_processor_cm;
1039
1040 // Instance of the concurrent mark is_alive closure for embedding
1041 // into the Concurrent Marking reference processor as the
1042 // _is_alive_non_header field. Supplying a value for the
1043 // _is_alive_non_header field is optional but doing so prevents
1044 // unnecessary additions to the discovered lists during reference
1045 // discovery.
1046 G1CMIsAliveClosure _is_alive_closure_cm;
1047
1048 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1049 HeapRegion** _worker_cset_start_region;
1050
1051 // Time stamp to validate the regions recorded in the cache
1052 // used by G1CollectedHeap::start_cset_region_for_worker().
1053 // The heap region entry for a given worker is valid iff
1054 // the associated time stamp value matches the current value
1055 // of G1CollectedHeap::_gc_time_stamp.
1056 unsigned int* _worker_cset_start_region_time_stamp;
1057
1058 enum G1H_process_strong_roots_tasks {
1059 G1H_PS_filter_satb_buffers,
1060 G1H_PS_refProcessor_oops_do,
1061 // Leave this one last.
1062 G1H_PS_NumElements
1063 };
1064
1065 SubTasksDone* _process_strong_tasks;
1066
1067 volatile bool _free_regions_coming;
1068
1069 public:
1070
1071 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1072
1073 void set_refine_cte_cl_concurrency(bool concurrent);
1074
1075 RefToScanQueue *task_queue(int i) const;
1076
1077 // A set of cards where updates happened during the GC
1078 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1079
1080 // A DirtyCardQueueSet that is used to hold cards that contain
1081 // references into the current collection set. This is used to
1082 // update the remembered sets of the regions in the collection
1083 // set in the event of an evacuation failure.
1084 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1085 { return _into_cset_dirty_card_queue_set; }
1086
1087 // Create a G1CollectedHeap with the specified policy.
1088 // Must call the initialize method afterwards.
1089 // May not return if something goes wrong.
1090 G1CollectedHeap(G1CollectorPolicy* policy);
1091
1092 // Initialize the G1CollectedHeap to have the initial and
1093 // maximum sizes and remembered and barrier sets
1094 // specified by the policy object.
1095 jint initialize();
1096
1097 // Return the (conservative) maximum heap alignment for any G1 heap
1098 static size_t conservative_max_heap_alignment();
1099
1100 // Initialize weak reference processing.
1101 virtual void ref_processing_init();
1102
1103 void set_par_threads(uint t) {
1104 SharedHeap::set_par_threads(t);
1105 // Done in SharedHeap but oddly there are
1106 // two _process_strong_tasks's in a G1CollectedHeap
1107 // so do it here too.
1108 _process_strong_tasks->set_n_threads(t);
1109 }
1110
1111 // Set _n_par_threads according to a policy TBD.
1112 void set_par_threads();
1113
1114 void set_n_termination(int t) {
1115 _process_strong_tasks->set_n_threads(t);
1116 }
1117
1118 virtual CollectedHeap::Name kind() const {
1119 return CollectedHeap::G1CollectedHeap;
1120 }
1121
1122 // The current policy object for the collector.
1123 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1124
1125 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1126
1127 // Adaptive size policy. No such thing for g1.
1128 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1129
1130 // The rem set and barrier set.
1131 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1132
1133 unsigned get_gc_time_stamp() {
1134 return _gc_time_stamp;
1135 }
1136
1137 void reset_gc_time_stamp() {
1138 _gc_time_stamp = 0;
1139 OrderAccess::fence();
1140 // Clear the cached CSet starting regions and time stamps.
1141 // Their validity is dependent on the GC timestamp.
1142 clear_cset_start_regions();
1143 }
1144
1145 void check_gc_time_stamps() PRODUCT_RETURN;
1146
1147 void increment_gc_time_stamp() {
1148 ++_gc_time_stamp;
1149 OrderAccess::fence();
1150 }
1151
1152 // Reset the given region's GC timestamp. If it's starts humongous,
1153 // also reset the GC timestamp of its corresponding
1154 // continues humongous regions too.
1155 void reset_gc_time_stamps(HeapRegion* hr);
1156
1157 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1158 DirtyCardQueue* into_cset_dcq,
1159 bool concurrent, int worker_i);
1160
1161 // The shared block offset table array.
1162 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1163
1164 // Reference Processing accessors
1165
1166 // The STW reference processor....
1167 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1168
1169 // The Concurrent Marking reference processor...
1170 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1171
1172 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1173 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1174
1175 virtual size_t capacity() const;
1176 virtual size_t used() const;
1177 // This should be called when we're not holding the heap lock. The
1178 // result might be a bit inaccurate.
1179 size_t used_unlocked() const;
1180 size_t recalculate_used() const;
1181
1182 // These virtual functions do the actual allocation.
1183 // Some heaps may offer a contiguous region for shared non-blocking
1184 // allocation, via inlined code (by exporting the address of the top and
1185 // end fields defining the extent of the contiguous allocation region.)
1186 // But G1CollectedHeap doesn't yet support this.
1187
1188 virtual bool is_maximal_no_gc() const {
1189 return _g1_storage.uncommitted_size() == 0;
1190 }
1191
1192 // The total number of regions in the heap.
1193 uint n_regions() { return _hrs.length(); }
1194
1195 // The max number of regions in the heap.
1196 uint max_regions() { return _hrs.max_length(); }
1197
1198 // The number of regions that are completely free.
1199 uint free_regions() { return _free_list.length(); }
1200
1201 // The number of regions that are not completely free.
1202 uint used_regions() { return n_regions() - free_regions(); }
1203
1204 // The number of regions available for "regular" expansion.
1205 uint expansion_regions() { return _expansion_regions; }
1206
1207 // Factory method for HeapRegion instances. It will return NULL if
1208 // the allocation fails.
1209 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1210
1211 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1212 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1213 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1214 void verify_dirty_young_regions() PRODUCT_RETURN;
1215
1216 // verify_region_sets() performs verification over the region
1217 // lists. It will be compiled in the product code to be used when
1218 // necessary (i.e., during heap verification).
1219 void verify_region_sets();
1220
1221 // verify_region_sets_optional() is planted in the code for
1222 // list verification in non-product builds (and it can be enabled in
1223 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1224 #if HEAP_REGION_SET_FORCE_VERIFY
1225 void verify_region_sets_optional() {
1226 verify_region_sets();
1227 }
1228 #else // HEAP_REGION_SET_FORCE_VERIFY
1229 void verify_region_sets_optional() { }
1230 #endif // HEAP_REGION_SET_FORCE_VERIFY
1231
1232 #ifdef ASSERT
1233 bool is_on_master_free_list(HeapRegion* hr) {
1234 return hr->containing_set() == &_free_list;
1235 }
1236
1237 bool is_in_humongous_set(HeapRegion* hr) {
1238 return hr->containing_set() == &_humongous_set;
1239 }
1240 #endif // ASSERT
1241
1242 // Wrapper for the region list operations that can be called from
1243 // methods outside this class.
1244
1245 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1246 _secondary_free_list.add_as_tail(list);
1247 }
1248
1249 void append_secondary_free_list() {
1250 _free_list.add_as_head(&_secondary_free_list);
1251 }
1252
1253 void append_secondary_free_list_if_not_empty_with_lock() {
1254 // If the secondary free list looks empty there's no reason to
1255 // take the lock and then try to append it.
1256 if (!_secondary_free_list.is_empty()) {
1257 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1258 append_secondary_free_list();
1259 }
1260 }
1261
1262 void old_set_remove(HeapRegion* hr) {
1263 _old_set.remove(hr);
1264 }
1265
1266 size_t non_young_capacity_bytes() {
1267 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1268 }
1269
1270 void set_free_regions_coming();
1271 void reset_free_regions_coming();
1272 bool free_regions_coming() { return _free_regions_coming; }
1273 void wait_while_free_regions_coming();
1274
1275 // Determine whether the given region is one that we are using as an
1276 // old GC alloc region.
1277 bool is_old_gc_alloc_region(HeapRegion* hr) {
1278 return hr == _retained_old_gc_alloc_region;
1279 }
1280
1281 // Perform a collection of the heap; intended for use in implementing
1282 // "System.gc". This probably implies as full a collection as the
1283 // "CollectedHeap" supports.
1284 virtual void collect(GCCause::Cause cause);
1285
1286 // The same as above but assume that the caller holds the Heap_lock.
1287 void collect_locked(GCCause::Cause cause);
1288
1289 // True iff an evacuation has failed in the most-recent collection.
1290 bool evacuation_failed() { return _evacuation_failed; }
1291
1292 // It will free a region if it has allocated objects in it that are
1293 // all dead. It calls either free_region() or
1294 // free_humongous_region() depending on the type of the region that
1295 // is passed to it.
1296 void free_region_if_empty(HeapRegion* hr,
1297 size_t* pre_used,
1298 FreeRegionList* free_list,
1299 OldRegionSet* old_proxy_set,
1300 HumongousRegionSet* humongous_proxy_set,
1301 HRRSCleanupTask* hrrs_cleanup_task,
1302 bool par);
1303
1304 // It appends the free list to the master free list and updates the
1305 // master humongous list according to the contents of the proxy
1306 // list. It also adjusts the total used bytes according to pre_used
1307 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1308 void update_sets_after_freeing_regions(size_t pre_used,
1309 FreeRegionList* free_list,
1310 OldRegionSet* old_proxy_set,
1311 HumongousRegionSet* humongous_proxy_set,
1312 bool par);
1313
1314 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1315 virtual bool is_in(const void* p) const;
1316
1317 // Return "TRUE" iff the given object address is within the collection
1318 // set.
1319 inline bool obj_in_cs(oop obj);
1320
1321 // Return "TRUE" iff the given object address is in the reserved
1322 // region of g1.
1323 bool is_in_g1_reserved(const void* p) const {
1324 return _g1_reserved.contains(p);
1325 }
1326
1327 // Returns a MemRegion that corresponds to the space that has been
1328 // reserved for the heap
1329 MemRegion g1_reserved() {
1330 return _g1_reserved;
1331 }
1332
1333 // Returns a MemRegion that corresponds to the space that has been
1334 // committed in the heap
1335 MemRegion g1_committed() {
1336 return _g1_committed;
1337 }
1338
1339 virtual bool is_in_closed_subset(const void* p) const;
1340
1341 G1SATBCardTableModRefBS* g1_barrier_set() {
1342 return (G1SATBCardTableModRefBS*) barrier_set();
1343 }
1344
1345 // This resets the card table to all zeros. It is used after
1346 // a collection pause which used the card table to claim cards.
1347 void cleanUpCardTable();
1348
1349 // Iteration functions.
1350
1351 // Iterate over all the ref-containing fields of all objects, calling
1352 // "cl.do_oop" on each.
1353 virtual void oop_iterate(ExtendedOopClosure* cl);
1354
1355 // Same as above, restricted to a memory region.
1356 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1357
1358 // Iterate over all objects, calling "cl.do_object" on each.
1359 virtual void object_iterate(ObjectClosure* cl);
1360
1361 virtual void safe_object_iterate(ObjectClosure* cl) {
1362 object_iterate(cl);
1363 }
1364
1365 // Iterate over all spaces in use in the heap, in ascending address order.
1366 virtual void space_iterate(SpaceClosure* cl);
1367
1368 // Iterate over heap regions, in address order, terminating the
1369 // iteration early if the "doHeapRegion" method returns "true".
1370 void heap_region_iterate(HeapRegionClosure* blk) const;
1371
1372 // Return the region with the given index. It assumes the index is valid.
1373 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1374
1375 // Divide the heap region sequence into "chunks" of some size (the number
1376 // of regions divided by the number of parallel threads times some
1377 // overpartition factor, currently 4). Assumes that this will be called
1378 // in parallel by ParallelGCThreads worker threads with distinct worker
1379 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1380 // calls will use the same "claim_value", and that that claim value is
1381 // different from the claim_value of any heap region before the start of
1382 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1383 // attempting to claim the first region in each chunk, and, if
1384 // successful, applying the closure to each region in the chunk (and
1385 // setting the claim value of the second and subsequent regions of the
1386 // chunk.) For now requires that "doHeapRegion" always returns "false",
1387 // i.e., that a closure never attempt to abort a traversal.
1388 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1389 uint worker,
1390 uint no_of_par_workers,
1391 jint claim_value);
1392
1393 // It resets all the region claim values to the default.
1394 void reset_heap_region_claim_values();
1395
1396 // Resets the claim values of regions in the current
1397 // collection set to the default.
1398 void reset_cset_heap_region_claim_values();
1399
1400 #ifdef ASSERT
1401 bool check_heap_region_claim_values(jint claim_value);
1402
1403 // Same as the routine above but only checks regions in the
1404 // current collection set.
1405 bool check_cset_heap_region_claim_values(jint claim_value);
1406 #endif // ASSERT
1407
1408 // Clear the cached cset start regions and (more importantly)
1409 // the time stamps. Called when we reset the GC time stamp.
1410 void clear_cset_start_regions();
1411
1412 // Given the id of a worker, obtain or calculate a suitable
1413 // starting region for iterating over the current collection set.
1414 HeapRegion* start_cset_region_for_worker(int worker_i);
1415
1416 // This is a convenience method that is used by the
1417 // HeapRegionIterator classes to calculate the starting region for
1418 // each worker so that they do not all start from the same region.
1419 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1420
1421 // Iterate over the regions (if any) in the current collection set.
1422 void collection_set_iterate(HeapRegionClosure* blk);
1423
1424 // As above but starting from region r
1425 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1426
1427 // Returns the first (lowest address) compactible space in the heap.
1428 virtual CompactibleSpace* first_compactible_space();
1429
1430 // A CollectedHeap will contain some number of spaces. This finds the
1431 // space containing a given address, or else returns NULL.
1432 virtual Space* space_containing(const void* addr) const;
1433
1434 // A G1CollectedHeap will contain some number of heap regions. This
1435 // finds the region containing a given address, or else returns NULL.
1436 template <class T>
1437 inline HeapRegion* heap_region_containing(const T addr) const;
1438
1439 // Like the above, but requires "addr" to be in the heap (to avoid a
1440 // null-check), and unlike the above, may return an continuing humongous
1441 // region.
1442 template <class T>
1443 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1444
1445 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1446 // each address in the (reserved) heap is a member of exactly
1447 // one block. The defining characteristic of a block is that it is
1448 // possible to find its size, and thus to progress forward to the next
1449 // block. (Blocks may be of different sizes.) Thus, blocks may
1450 // represent Java objects, or they might be free blocks in a
1451 // free-list-based heap (or subheap), as long as the two kinds are
1452 // distinguishable and the size of each is determinable.
1453
1454 // Returns the address of the start of the "block" that contains the
1455 // address "addr". We say "blocks" instead of "object" since some heaps
1456 // may not pack objects densely; a chunk may either be an object or a
1457 // non-object.
1458 virtual HeapWord* block_start(const void* addr) const;
1459
1460 // Requires "addr" to be the start of a chunk, and returns its size.
1461 // "addr + size" is required to be the start of a new chunk, or the end
1462 // of the active area of the heap.
1463 virtual size_t block_size(const HeapWord* addr) const;
1464
1465 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1466 // the block is an object.
1467 virtual bool block_is_obj(const HeapWord* addr) const;
1468
1469 // Does this heap support heap inspection? (+PrintClassHistogram)
1470 virtual bool supports_heap_inspection() const { return true; }
1471
1472 // Section on thread-local allocation buffers (TLABs)
1473 // See CollectedHeap for semantics.
1474
1475 bool supports_tlab_allocation() const;
1476 size_t tlab_capacity(Thread* ignored) const;
1477 size_t tlab_used(Thread* ignored) const;
1478 size_t max_tlab_size() const;
1479 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1480
1481 // Can a compiler initialize a new object without store barriers?
1482 // This permission only extends from the creation of a new object
1483 // via a TLAB up to the first subsequent safepoint. If such permission
1484 // is granted for this heap type, the compiler promises to call
1485 // defer_store_barrier() below on any slow path allocation of
1486 // a new object for which such initializing store barriers will
1487 // have been elided. G1, like CMS, allows this, but should be
1488 // ready to provide a compensating write barrier as necessary
1489 // if that storage came out of a non-young region. The efficiency
1490 // of this implementation depends crucially on being able to
1491 // answer very efficiently in constant time whether a piece of
1492 // storage in the heap comes from a young region or not.
1493 // See ReduceInitialCardMarks.
1494 virtual bool can_elide_tlab_store_barriers() const {
1495 return true;
1496 }
1497
1498 virtual bool card_mark_must_follow_store() const {
1499 return true;
1500 }
1501
1502 bool is_in_young(const oop obj) {
1503 HeapRegion* hr = heap_region_containing(obj);
1504 return hr != NULL && hr->is_young();
1505 }
1506
1507 #ifdef ASSERT
1508 virtual bool is_in_partial_collection(const void* p);
1509 #endif
1510
1511 virtual bool is_scavengable(const void* addr);
1512
1513 // We don't need barriers for initializing stores to objects
1514 // in the young gen: for the SATB pre-barrier, there is no
1515 // pre-value that needs to be remembered; for the remembered-set
1516 // update logging post-barrier, we don't maintain remembered set
1517 // information for young gen objects.
1518 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1519 return is_in_young(new_obj);
1520 }
1521
1522 // Returns "true" iff the given word_size is "very large".
1523 static bool isHumongous(size_t word_size) {
1524 // Note this has to be strictly greater-than as the TLABs
1525 // are capped at the humongous threshold and we want to
1526 // ensure that we don't try to allocate a TLAB as
1527 // humongous and that we don't allocate a humongous
1528 // object in a TLAB.
1529 return word_size > _humongous_object_threshold_in_words;
1530 }
1531
1532 // Update mod union table with the set of dirty cards.
1533 void updateModUnion();
1534
1535 // Set the mod union bits corresponding to the given memRegion. Note
1536 // that this is always a safe operation, since it doesn't clear any
1537 // bits.
1538 void markModUnionRange(MemRegion mr);
1539
1540 // Records the fact that a marking phase is no longer in progress.
1541 void set_marking_complete() {
1542 _mark_in_progress = false;
1543 }
1544 void set_marking_started() {
1545 _mark_in_progress = true;
1546 }
1547 bool mark_in_progress() {
1548 return _mark_in_progress;
1549 }
1550
1551 // Print the maximum heap capacity.
1552 virtual size_t max_capacity() const;
1553
1554 virtual jlong millis_since_last_gc();
1555
1556
1557 // Convenience function to be used in situations where the heap type can be
1558 // asserted to be this type.
1559 static G1CollectedHeap* heap();
1560
1561 void set_region_short_lived_locked(HeapRegion* hr);
1562 // add appropriate methods for any other surv rate groups
1563
1564 YoungList* young_list() const { return _young_list; }
1565
1566 // debugging
1567 bool check_young_list_well_formed() {
1568 return _young_list->check_list_well_formed();
1569 }
1570
1571 bool check_young_list_empty(bool check_heap,
1572 bool check_sample = true);
1573
1574 // *** Stuff related to concurrent marking. It's not clear to me that so
1575 // many of these need to be public.
1576
1577 // The functions below are helper functions that a subclass of
1578 // "CollectedHeap" can use in the implementation of its virtual
1579 // functions.
1580 // This performs a concurrent marking of the live objects in a
1581 // bitmap off to the side.
1582 void doConcurrentMark();
1583
1584 bool isMarkedPrev(oop obj) const;
1585 bool isMarkedNext(oop obj) const;
1586
1587 // Determine if an object is dead, given the object and also
1588 // the region to which the object belongs. An object is dead
1589 // iff a) it was not allocated since the last mark and b) it
1590 // is not marked.
1591
1592 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1593 return
1594 !hr->obj_allocated_since_prev_marking(obj) &&
1595 !isMarkedPrev(obj);
1596 }
1597
1598 // This function returns true when an object has been
1599 // around since the previous marking and hasn't yet
1600 // been marked during this marking.
1601
1602 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1603 return
1604 !hr->obj_allocated_since_next_marking(obj) &&
1605 !isMarkedNext(obj);
1606 }
1607
1608 // Determine if an object is dead, given only the object itself.
1609 // This will find the region to which the object belongs and
1610 // then call the region version of the same function.
1611
1612 // Added if it is NULL it isn't dead.
1613
1614 bool is_obj_dead(const oop obj) const {
1615 const HeapRegion* hr = heap_region_containing(obj);
1616 if (hr == NULL) {
1617 if (obj == NULL) return false;
1618 else return true;
1619 }
1620 else return is_obj_dead(obj, hr);
1621 }
1622
1623 bool is_obj_ill(const oop obj) const {
1624 const HeapRegion* hr = heap_region_containing(obj);
1625 if (hr == NULL) {
1626 if (obj == NULL) return false;
1627 else return true;
1628 }
1629 else return is_obj_ill(obj, hr);
1630 }
1631
1632 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1633 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1634 bool is_marked(oop obj, VerifyOption vo);
1635 const char* top_at_mark_start_str(VerifyOption vo);
1636
1637 ConcurrentMark* concurrent_mark() const { return _cm; }
1638
1639 // Refinement
1640
1641 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1642
1643 // The dirty cards region list is used to record a subset of regions
1644 // whose cards need clearing. The list if populated during the
1645 // remembered set scanning and drained during the card table
1646 // cleanup. Although the methods are reentrant, population/draining
1647 // phases must not overlap. For synchronization purposes the last
1648 // element on the list points to itself.
1649 HeapRegion* _dirty_cards_region_list;
1650 void push_dirty_cards_region(HeapRegion* hr);
1651 HeapRegion* pop_dirty_cards_region();
1652
1653 // Optimized nmethod scanning support routines
1654
1655 // Register the given nmethod with the G1 heap.
1656 virtual void register_nmethod(nmethod* nm);
1657
1658 // Unregister the given nmethod from the G1 heap.
1659 virtual void unregister_nmethod(nmethod* nm);
1660
1661 // Migrate the nmethods in the code root lists of the regions
1662 // in the collection set to regions in to-space. In the event
1663 // of an evacuation failure, nmethods that reference objects
1664 // that were not successfully evacuated are not migrated.
1665 void migrate_strong_code_roots();
1666
1667 // During an initial mark pause, mark all the code roots that
1668 // point into regions *not* in the collection set.
1669 void mark_strong_code_roots(uint worker_id);
1670
1671 // Rebuild the strong code root lists for each region
1672 // after a full GC.
1673 void rebuild_strong_code_roots();
1674
1675 // Delete entries for dead interned string and clean up unreferenced symbols
1676 // in symbol table, possibly in parallel.
1677 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
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