1 /*
2 * Copyright (c) 2001, 2012, 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.
8 *
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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/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
40 #include "utilities/stack.hpp"
41
42 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
43 // It uses the "Garbage First" heap organization and algorithm, which
44 // may combine concurrent marking with parallel, incremental compaction of
45 // heap subsets that will yield large amounts of garbage.
46
47 class HeapRegion;
48 class HRRSCleanupTask;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1KlassScanClosure;
52 class G1ScanHeapEvacClosure;
53 class ObjectClosure;
54 class SpaceClosure;
55 class CompactibleSpaceClosure;
56 class Space;
57 class G1CollectorPolicy;
58 class GenRemSet;
59 class G1RemSet;
60 class HeapRegionRemSetIterator;
61 class ConcurrentMark;
62 class ConcurrentMarkThread;
63 class ConcurrentG1Refine;
64 class GenerationCounters;
65
66 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
67 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
68
69 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
70 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71
72 enum GCAllocPurpose {
73 GCAllocPurposeStart = 0,
74 GCAllocForTenured = GCAllocPurposeStart,
75 GCAllocForSurvived = GCAllocPurposeStart + 1,
76 GCAllocPurposeCount = GCAllocPurposeStart + 2
77 };
78
79 class YoungList : public CHeapObj<mtGC> {
80 private:
81 G1CollectedHeap* _g1h;
82
83 HeapRegion* _head;
84
85 HeapRegion* _survivor_head;
86 HeapRegion* _survivor_tail;
87
88 HeapRegion* _curr;
89
90 uint _length;
91 uint _survivor_length;
92
93 size_t _last_sampled_rs_lengths;
94 size_t _sampled_rs_lengths;
95
96 void empty_list(HeapRegion* list);
97
98 public:
99 YoungList(G1CollectedHeap* g1h);
100
101 void push_region(HeapRegion* hr);
102 void add_survivor_region(HeapRegion* hr);
103
104 void empty_list();
105 bool is_empty() { return _length == 0; }
106 uint length() { return _length; }
107 uint survivor_length() { return _survivor_length; }
108
109 // Currently we do not keep track of the used byte sum for the
110 // young list and the survivors and it'd be quite a lot of work to
111 // do so. When we'll eventually replace the young list with
112 // instances of HeapRegionLinkedList we'll get that for free. So,
113 // we'll report the more accurate information then.
114 size_t eden_used_bytes() {
115 assert(length() >= survivor_length(), "invariant");
116 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
117 }
118 size_t survivor_used_bytes() {
119 return (size_t) survivor_length() * HeapRegion::GrainBytes;
120 }
121
122 void rs_length_sampling_init();
123 bool rs_length_sampling_more();
124 void rs_length_sampling_next();
125
126 void reset_sampled_info() {
127 _last_sampled_rs_lengths = 0;
128 }
129 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
130
131 // for development purposes
132 void reset_auxilary_lists();
133 void clear() { _head = NULL; _length = 0; }
134
135 void clear_survivors() {
136 _survivor_head = NULL;
137 _survivor_tail = NULL;
138 _survivor_length = 0;
139 }
140
141 HeapRegion* first_region() { return _head; }
142 HeapRegion* first_survivor_region() { return _survivor_head; }
143 HeapRegion* last_survivor_region() { return _survivor_tail; }
144
145 // debugging
146 bool check_list_well_formed();
147 bool check_list_empty(bool check_sample = true);
148 void print();
149 };
150
151 class MutatorAllocRegion : public G1AllocRegion {
152 protected:
153 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
154 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
155 public:
156 MutatorAllocRegion()
157 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
158 };
159
160 // The G1 STW is alive closure.
161 // An instance is embedded into the G1CH and used as the
162 // (optional) _is_alive_non_header closure in the STW
163 // reference processor. It is also extensively used during
164 // refence processing during STW evacuation pauses.
165 class G1STWIsAliveClosure: public BoolObjectClosure {
166 G1CollectedHeap* _g1;
167 public:
168 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
169 bool do_object_b(oop p);
170 };
171
172 class SurvivorGCAllocRegion : public G1AllocRegion {
173 protected:
174 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
175 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
176 public:
177 SurvivorGCAllocRegion()
178 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
179 };
180
181 class OldGCAllocRegion : public G1AllocRegion {
182 protected:
183 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
184 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
185 public:
186 OldGCAllocRegion()
187 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
188 };
189
190 class RefineCardTableEntryClosure;
191
192 class G1CollectedHeap : public SharedHeap {
193 friend class VM_G1CollectForAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
200
201 // Closures used in implementation.
202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
203 friend class G1ParCopyClosure;
204 friend class G1IsAliveClosure;
205 friend class G1EvacuateFollowersClosure;
206 friend class G1ParScanThreadState;
207 friend class G1ParScanClosureSuper;
208 friend class G1ParEvacuateFollowersClosure;
209 friend class G1ParTask;
210 friend class G1FreeGarbageRegionClosure;
211 friend class RefineCardTableEntryClosure;
212 friend class G1PrepareCompactClosure;
213 friend class RegionSorter;
214 friend class RegionResetter;
215 friend class CountRCClosure;
216 friend class EvacPopObjClosure;
217 friend class G1ParCleanupCTTask;
218
219 // Other related classes.
220 friend class G1MarkSweep;
221
222 private:
223 // The one and only G1CollectedHeap, so static functions can find it.
224 static G1CollectedHeap* _g1h;
225
226 static size_t _humongous_object_threshold_in_words;
227
228 // Storage for the G1 heap.
229 VirtualSpace _g1_storage;
230 MemRegion _g1_reserved;
231
232 // The part of _g1_storage that is currently committed.
233 MemRegion _g1_committed;
234
235 // The master free list. It will satisfy all new region allocations.
236 MasterFreeRegionList _free_list;
237
238 // The secondary free list which contains regions that have been
239 // freed up during the cleanup process. This will be appended to the
240 // master free list when appropriate.
241 SecondaryFreeRegionList _secondary_free_list;
242
243 // It keeps track of the old regions.
244 MasterOldRegionSet _old_set;
245
246 // It keeps track of the humongous regions.
247 MasterHumongousRegionSet _humongous_set;
248
249 // The number of regions we could create by expansion.
250 uint _expansion_regions;
251
252 // The block offset table for the G1 heap.
253 G1BlockOffsetSharedArray* _bot_shared;
254
255 // Tears down the region sets / lists so that they are empty and the
256 // regions on the heap do not belong to a region set / list. The
257 // only exception is the humongous set which we leave unaltered. If
258 // free_list_only is true, it will only tear down the master free
259 // list. It is called before a Full GC (free_list_only == false) or
260 // before heap shrinking (free_list_only == true).
261 void tear_down_region_sets(bool free_list_only);
262
263 // Rebuilds the region sets / lists so that they are repopulated to
264 // reflect the contents of the heap. The only exception is the
265 // humongous set which was not torn down in the first place. If
266 // free_list_only is true, it will only rebuild the master free
267 // list. It is called after a Full GC (free_list_only == false) or
268 // after heap shrinking (free_list_only == true).
269 void rebuild_region_sets(bool free_list_only);
270
271 // The sequence of all heap regions in the heap.
272 HeapRegionSeq _hrs;
273
274 // Alloc region used to satisfy mutator allocation requests.
275 MutatorAllocRegion _mutator_alloc_region;
276
277 // Alloc region used to satisfy allocation requests by the GC for
278 // survivor objects.
279 SurvivorGCAllocRegion _survivor_gc_alloc_region;
280
281 // PLAB sizing policy for survivors.
282 PLABStats _survivor_plab_stats;
283
284 // Alloc region used to satisfy allocation requests by the GC for
285 // old objects.
286 OldGCAllocRegion _old_gc_alloc_region;
287
288 // PLAB sizing policy for tenured objects.
289 PLABStats _old_plab_stats;
290
291 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
292 PLABStats* stats = NULL;
293
294 switch (purpose) {
295 case GCAllocForSurvived:
296 stats = &_survivor_plab_stats;
297 break;
298 case GCAllocForTenured:
299 stats = &_old_plab_stats;
300 break;
301 default:
302 assert(false, "unrecognized GCAllocPurpose");
303 }
304
305 return stats;
306 }
307
308 // The last old region we allocated to during the last GC.
309 // Typically, it is not full so we should re-use it during the next GC.
310 HeapRegion* _retained_old_gc_alloc_region;
311
312 // It specifies whether we should attempt to expand the heap after a
313 // region allocation failure. If heap expansion fails we set this to
314 // false so that we don't re-attempt the heap expansion (it's likely
315 // that subsequent expansion attempts will also fail if one fails).
316 // Currently, it is only consulted during GC and it's reset at the
317 // start of each GC.
318 bool _expand_heap_after_alloc_failure;
319
320 // It resets the mutator alloc region before new allocations can take place.
321 void init_mutator_alloc_region();
322
323 // It releases the mutator alloc region.
324 void release_mutator_alloc_region();
325
326 // It initializes the GC alloc regions at the start of a GC.
327 void init_gc_alloc_regions();
328
329 // It releases the GC alloc regions at the end of a GC.
330 void release_gc_alloc_regions(uint no_of_gc_workers);
331
332 // It does any cleanup that needs to be done on the GC alloc regions
333 // before a Full GC.
334 void abandon_gc_alloc_regions();
335
336 // Helper for monitoring and management support.
337 G1MonitoringSupport* _g1mm;
338
339 // Determines PLAB size for a particular allocation purpose.
340 size_t desired_plab_sz(GCAllocPurpose purpose);
341
342 // Outside of GC pauses, the number of bytes used in all regions other
343 // than the current allocation region.
344 size_t _summary_bytes_used;
345
346 // This is used for a quick test on whether a reference points into
347 // the collection set or not. Basically, we have an array, with one
348 // byte per region, and that byte denotes whether the corresponding
349 // region is in the collection set or not. The entry corresponding
350 // the bottom of the heap, i.e., region 0, is pointed to by
351 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
352 // biased so that it actually points to address 0 of the address
353 // space, to make the test as fast as possible (we can simply shift
354 // the address to address into it, instead of having to subtract the
355 // bottom of the heap from the address before shifting it; basically
356 // it works in the same way the card table works).
357 bool* _in_cset_fast_test;
358
359 // The allocated array used for the fast test on whether a reference
360 // points into the collection set or not. This field is also used to
361 // free the array.
362 bool* _in_cset_fast_test_base;
363
364 // The length of the _in_cset_fast_test_base array.
365 uint _in_cset_fast_test_length;
366
367 volatile unsigned _gc_time_stamp;
368
369 size_t* _surviving_young_words;
370
371 G1HRPrinter _hr_printer;
372
373 void setup_surviving_young_words();
374 void update_surviving_young_words(size_t* surv_young_words);
375 void cleanup_surviving_young_words();
376
377 // It decides whether an explicit GC should start a concurrent cycle
378 // instead of doing a STW GC. Currently, a concurrent cycle is
379 // explicitly started if:
380 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
381 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
382 // (c) cause == _g1_humongous_allocation
383 bool should_do_concurrent_full_gc(GCCause::Cause cause);
384
385 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
386 // concurrent cycles) we have started.
387 volatile unsigned int _old_marking_cycles_started;
388
389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
390 // concurrent cycles) we have completed.
391 volatile unsigned int _old_marking_cycles_completed;
392
393 // This is a non-product method that is helpful for testing. It is
394 // called at the end of a GC and artificially expands the heap by
395 // allocating a number of dead regions. This way we can induce very
396 // frequent marking cycles and stress the cleanup / concurrent
397 // cleanup code more (as all the regions that will be allocated by
398 // this method will be found dead by the marking cycle).
399 void allocate_dummy_regions() PRODUCT_RETURN;
400
401 // Clear RSets after a compaction. It also resets the GC time stamps.
402 void clear_rsets_post_compaction();
403
404 // If the HR printer is active, dump the state of the regions in the
405 // heap after a compaction.
406 void print_hrs_post_compaction();
407
408 double verify(bool guard, const char* msg);
409 void verify_before_gc();
410 void verify_after_gc();
411
412 void log_gc_header();
413 void log_gc_footer(double pause_time_sec);
414
415 // These are macros so that, if the assert fires, we get the correct
416 // line number, file, etc.
417
418 #define heap_locking_asserts_err_msg(_extra_message_) \
419 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
420 (_extra_message_), \
421 BOOL_TO_STR(Heap_lock->owned_by_self()), \
422 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
423 BOOL_TO_STR(Thread::current()->is_VM_thread()))
424
425 #define assert_heap_locked() \
426 do { \
427 assert(Heap_lock->owned_by_self(), \
428 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
429 } while (0)
430
431 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
432 do { \
433 assert(Heap_lock->owned_by_self() || \
434 (SafepointSynchronize::is_at_safepoint() && \
435 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
436 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
437 "should be at a safepoint")); \
438 } while (0)
439
440 #define assert_heap_locked_and_not_at_safepoint() \
441 do { \
442 assert(Heap_lock->owned_by_self() && \
443 !SafepointSynchronize::is_at_safepoint(), \
444 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
445 "should not be at a safepoint")); \
446 } while (0)
447
448 #define assert_heap_not_locked() \
449 do { \
450 assert(!Heap_lock->owned_by_self(), \
451 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
452 } while (0)
453
454 #define assert_heap_not_locked_and_not_at_safepoint() \
455 do { \
456 assert(!Heap_lock->owned_by_self() && \
457 !SafepointSynchronize::is_at_safepoint(), \
458 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
459 "should not be at a safepoint")); \
460 } while (0)
461
462 #define assert_at_safepoint(_should_be_vm_thread_) \
463 do { \
464 assert(SafepointSynchronize::is_at_safepoint() && \
465 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
466 heap_locking_asserts_err_msg("should be at a safepoint")); \
467 } while (0)
468
469 #define assert_not_at_safepoint() \
470 do { \
471 assert(!SafepointSynchronize::is_at_safepoint(), \
472 heap_locking_asserts_err_msg("should not be at a safepoint")); \
473 } while (0)
474
475 protected:
476
477 // The young region list.
478 YoungList* _young_list;
479
480 // The current policy object for the collector.
481 G1CollectorPolicy* _g1_policy;
482
483 // This is the second level of trying to allocate a new region. If
484 // new_region() didn't find a region on the free_list, this call will
485 // check whether there's anything available on the
486 // secondary_free_list and/or wait for more regions to appear on
487 // that list, if _free_regions_coming is set.
488 HeapRegion* new_region_try_secondary_free_list();
489
490 // Try to allocate a single non-humongous HeapRegion sufficient for
491 // an allocation of the given word_size. If do_expand is true,
492 // attempt to expand the heap if necessary to satisfy the allocation
493 // request.
494 HeapRegion* new_region(size_t word_size, bool do_expand);
495
496 // Attempt to satisfy a humongous allocation request of the given
497 // size by finding a contiguous set of free regions of num_regions
498 // length and remove them from the master free list. Return the
499 // index of the first region or G1_NULL_HRS_INDEX if the search
500 // was unsuccessful.
501 uint humongous_obj_allocate_find_first(uint num_regions,
502 size_t word_size);
503
504 // Initialize a contiguous set of free regions of length num_regions
505 // and starting at index first so that they appear as a single
506 // humongous region.
507 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
508 uint num_regions,
509 size_t word_size);
510
511 // Attempt to allocate a humongous object of the given size. Return
512 // NULL if unsuccessful.
513 HeapWord* humongous_obj_allocate(size_t word_size);
514
515 // The following two methods, allocate_new_tlab() and
516 // mem_allocate(), are the two main entry points from the runtime
517 // into the G1's allocation routines. They have the following
518 // assumptions:
519 //
520 // * They should both be called outside safepoints.
521 //
522 // * They should both be called without holding the Heap_lock.
523 //
524 // * All allocation requests for new TLABs should go to
525 // allocate_new_tlab().
526 //
527 // * All non-TLAB allocation requests should go to mem_allocate().
528 //
529 // * If either call cannot satisfy the allocation request using the
530 // current allocating region, they will try to get a new one. If
531 // this fails, they will attempt to do an evacuation pause and
532 // retry the allocation.
533 //
534 // * If all allocation attempts fail, even after trying to schedule
535 // an evacuation pause, allocate_new_tlab() will return NULL,
536 // whereas mem_allocate() will attempt a heap expansion and/or
537 // schedule a Full GC.
538 //
539 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
540 // should never be called with word_size being humongous. All
541 // humongous allocation requests should go to mem_allocate() which
542 // will satisfy them with a special path.
543
544 virtual HeapWord* allocate_new_tlab(size_t word_size);
545
546 virtual HeapWord* mem_allocate(size_t word_size,
547 bool* gc_overhead_limit_was_exceeded);
548
549 // The following three methods take a gc_count_before_ret
550 // parameter which is used to return the GC count if the method
551 // returns NULL. Given that we are required to read the GC count
552 // while holding the Heap_lock, and these paths will take the
553 // Heap_lock at some point, it's easier to get them to read the GC
554 // count while holding the Heap_lock before they return NULL instead
555 // of the caller (namely: mem_allocate()) having to also take the
556 // Heap_lock just to read the GC count.
557
558 // First-level mutator allocation attempt: try to allocate out of
559 // the mutator alloc region without taking the Heap_lock. This
560 // should only be used for non-humongous allocations.
561 inline HeapWord* attempt_allocation(size_t word_size,
562 unsigned int* gc_count_before_ret,
563 int* gclocker_retry_count_ret);
564
565 // Second-level mutator allocation attempt: take the Heap_lock and
566 // retry the allocation attempt, potentially scheduling a GC
567 // pause. This should only be used for non-humongous allocations.
568 HeapWord* attempt_allocation_slow(size_t word_size,
569 unsigned int* gc_count_before_ret,
570 int* gclocker_retry_count_ret);
571
572 // Takes the Heap_lock and attempts a humongous allocation. It can
573 // potentially schedule a GC pause.
574 HeapWord* attempt_allocation_humongous(size_t word_size,
575 unsigned int* gc_count_before_ret,
576 int* gclocker_retry_count_ret);
577
578 // Allocation attempt that should be called during safepoints (e.g.,
579 // at the end of a successful GC). expect_null_mutator_alloc_region
580 // specifies whether the mutator alloc region is expected to be NULL
581 // or not.
582 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
583 bool expect_null_mutator_alloc_region);
584
585 // It dirties the cards that cover the block so that so that the post
586 // write barrier never queues anything when updating objects on this
587 // block. It is assumed (and in fact we assert) that the block
588 // belongs to a young region.
589 inline void dirty_young_block(HeapWord* start, size_t word_size);
590
591 // Allocate blocks during garbage collection. Will ensure an
592 // allocation region, either by picking one or expanding the
593 // heap, and then allocate a block of the given size. The block
594 // may not be a humongous - it must fit into a single heap region.
595 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
596
597 // Ensure that no further allocations can happen in "r", bearing in mind
598 // that parallel threads might be attempting allocations.
599 void par_allocate_remaining_space(HeapRegion* r);
600
601 // Allocation attempt during GC for a survivor object / PLAB.
602 inline HeapWord* survivor_attempt_allocation(size_t word_size);
603
604 // Allocation attempt during GC for an old object / PLAB.
605 inline HeapWord* old_attempt_allocation(size_t word_size);
606
607 // These methods are the "callbacks" from the G1AllocRegion class.
608
609 // For mutator alloc regions.
610 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
611 void retire_mutator_alloc_region(HeapRegion* alloc_region,
612 size_t allocated_bytes);
613
614 // For GC alloc regions.
615 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
616 GCAllocPurpose ap);
617 void retire_gc_alloc_region(HeapRegion* alloc_region,
618 size_t allocated_bytes, GCAllocPurpose ap);
619
620 // - if explicit_gc is true, the GC is for a System.gc() or a heap
621 // inspection request and should collect the entire heap
622 // - if clear_all_soft_refs is true, all soft references should be
623 // cleared during the GC
624 // - if explicit_gc is false, word_size describes the allocation that
625 // the GC should attempt (at least) to satisfy
626 // - it returns false if it is unable to do the collection due to the
627 // GC locker being active, true otherwise
628 bool do_collection(bool explicit_gc,
629 bool clear_all_soft_refs,
630 size_t word_size);
631
632 // Callback from VM_G1CollectFull operation.
633 // Perform a full collection.
634 virtual void do_full_collection(bool clear_all_soft_refs);
635
636 // Resize the heap if necessary after a full collection. If this is
637 // after a collect-for allocation, "word_size" is the allocation size,
638 // and will be considered part of the used portion of the heap.
639 void resize_if_necessary_after_full_collection(size_t word_size);
640
641 // Callback from VM_G1CollectForAllocation operation.
642 // This function does everything necessary/possible to satisfy a
643 // failed allocation request (including collection, expansion, etc.)
644 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
645
646 // Attempting to expand the heap sufficiently
647 // to support an allocation of the given "word_size". If
648 // successful, perform the allocation and return the address of the
649 // allocated block, or else "NULL".
650 HeapWord* expand_and_allocate(size_t word_size);
651
652 // Process any reference objects discovered during
653 // an incremental evacuation pause.
654 void process_discovered_references(uint no_of_gc_workers);
655
656 // Enqueue any remaining discovered references
657 // after processing.
658 void enqueue_discovered_references(uint no_of_gc_workers);
659
660 public:
661
662 G1MonitoringSupport* g1mm() {
663 assert(_g1mm != NULL, "should have been initialized");
664 return _g1mm;
665 }
666
667 // Expand the garbage-first heap by at least the given size (in bytes!).
668 // Returns true if the heap was expanded by the requested amount;
669 // false otherwise.
670 // (Rounds up to a HeapRegion boundary.)
671 bool expand(size_t expand_bytes);
672
673 // Do anything common to GC's.
674 virtual void gc_prologue(bool full);
675 virtual void gc_epilogue(bool full);
676
677 // We register a region with the fast "in collection set" test. We
678 // simply set to true the array slot corresponding to this region.
679 void register_region_with_in_cset_fast_test(HeapRegion* r) {
680 assert(_in_cset_fast_test_base != NULL, "sanity");
681 assert(r->in_collection_set(), "invariant");
682 uint index = r->hrs_index();
683 assert(index < _in_cset_fast_test_length, "invariant");
684 assert(!_in_cset_fast_test_base[index], "invariant");
685 _in_cset_fast_test_base[index] = true;
686 }
687
688 // This is a fast test on whether a reference points into the
689 // collection set or not. It does not assume that the reference
690 // points into the heap; if it doesn't, it will return false.
691 bool in_cset_fast_test(oop obj) {
692 assert(_in_cset_fast_test != NULL, "sanity");
693 if (_g1_committed.contains((HeapWord*) obj)) {
694 // no need to subtract the bottom of the heap from obj,
695 // _in_cset_fast_test is biased
696 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes;
697 bool ret = _in_cset_fast_test[index];
698 // let's make sure the result is consistent with what the slower
699 // test returns
700 assert( ret || !obj_in_cs(obj), "sanity");
701 assert(!ret || obj_in_cs(obj), "sanity");
702 return ret;
703 } else {
704 return false;
705 }
706 }
707
708 void clear_cset_fast_test() {
709 assert(_in_cset_fast_test_base != NULL, "sanity");
710 memset(_in_cset_fast_test_base, false,
711 (size_t) _in_cset_fast_test_length * sizeof(bool));
712 }
713
714 // This is called at the start of either a concurrent cycle or a Full
715 // GC to update the number of old marking cycles started.
716 void increment_old_marking_cycles_started();
717
718 // This is called at the end of either a concurrent cycle or a Full
719 // GC to update the number of old marking cycles completed. Those two
720 // can happen in a nested fashion, i.e., we start a concurrent
721 // cycle, a Full GC happens half-way through it which ends first,
722 // and then the cycle notices that a Full GC happened and ends
723 // too. The concurrent parameter is a boolean to help us do a bit
724 // tighter consistency checking in the method. If concurrent is
725 // false, the caller is the inner caller in the nesting (i.e., the
726 // Full GC). If concurrent is true, the caller is the outer caller
727 // in this nesting (i.e., the concurrent cycle). Further nesting is
728 // not currently supported. The end of this call also notifies
729 // the FullGCCount_lock in case a Java thread is waiting for a full
730 // GC to happen (e.g., it called System.gc() with
731 // +ExplicitGCInvokesConcurrent).
732 void increment_old_marking_cycles_completed(bool concurrent);
733
734 unsigned int old_marking_cycles_completed() {
735 return _old_marking_cycles_completed;
736 }
737
738 G1HRPrinter* hr_printer() { return &_hr_printer; }
739
740 protected:
741
742 // Shrink the garbage-first heap by at most the given size (in bytes!).
743 // (Rounds down to a HeapRegion boundary.)
744 virtual void shrink(size_t expand_bytes);
745 void shrink_helper(size_t expand_bytes);
746
747 #if TASKQUEUE_STATS
748 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
749 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
750 void reset_taskqueue_stats();
751 #endif // TASKQUEUE_STATS
752
753 // Schedule the VM operation that will do an evacuation pause to
754 // satisfy an allocation request of word_size. *succeeded will
755 // return whether the VM operation was successful (it did do an
756 // evacuation pause) or not (another thread beat us to it or the GC
757 // locker was active). Given that we should not be holding the
758 // Heap_lock when we enter this method, we will pass the
759 // gc_count_before (i.e., total_collections()) as a parameter since
760 // it has to be read while holding the Heap_lock. Currently, both
761 // methods that call do_collection_pause() release the Heap_lock
762 // before the call, so it's easy to read gc_count_before just before.
763 HeapWord* do_collection_pause(size_t word_size,
764 unsigned int gc_count_before,
765 bool* succeeded);
766
767 // The guts of the incremental collection pause, executed by the vm
768 // thread. It returns false if it is unable to do the collection due
769 // to the GC locker being active, true otherwise
770 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
771
772 // Actually do the work of evacuating the collection set.
773 void evacuate_collection_set();
774
775 // The g1 remembered set of the heap.
776 G1RemSet* _g1_rem_set;
777 // And it's mod ref barrier set, used to track updates for the above.
778 ModRefBarrierSet* _mr_bs;
779
780 // A set of cards that cover the objects for which the Rsets should be updated
781 // concurrently after the collection.
782 DirtyCardQueueSet _dirty_card_queue_set;
783
784 // The closure used to refine a single card.
785 RefineCardTableEntryClosure* _refine_cte_cl;
786
787 // A function to check the consistency of dirty card logs.
788 void check_ct_logs_at_safepoint();
789
790 // A DirtyCardQueueSet that is used to hold cards that contain
791 // references into the current collection set. This is used to
792 // update the remembered sets of the regions in the collection
793 // set in the event of an evacuation failure.
794 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
795
796 // After a collection pause, make the regions in the CS into free
797 // regions.
798 void free_collection_set(HeapRegion* cs_head);
799
800 // Abandon the current collection set without recording policy
801 // statistics or updating free lists.
802 void abandon_collection_set(HeapRegion* cs_head);
803
804 // Applies "scan_non_heap_roots" to roots outside the heap,
805 // "scan_rs" to roots inside the heap (having done "set_region" to
806 // indicate the region in which the root resides),
807 // and does "scan_metadata" If "scan_rs" is
808 // NULL, then this step is skipped. The "worker_i"
809 // param is for use with parallel roots processing, and should be
810 // the "i" of the calling parallel worker thread's work(i) function.
811 // In the sequential case this param will be ignored.
812 void g1_process_strong_roots(bool is_scavenging,
813 ScanningOption so,
814 OopClosure* scan_non_heap_roots,
815 OopsInHeapRegionClosure* scan_rs,
816 G1KlassScanClosure* scan_klasses,
817 int worker_i);
818
819 // Apply "blk" to all the weak roots of the system. These include
820 // JNI weak roots, the code cache, system dictionary, symbol table,
821 // string table, and referents of reachable weak refs.
822 void g1_process_weak_roots(OopClosure* root_closure);
823
824 // Frees a non-humongous region by initializing its contents and
825 // adding it to the free list that's passed as a parameter (this is
826 // usually a local list which will be appended to the master free
827 // list later). The used bytes of freed regions are accumulated in
828 // pre_used. If par is true, the region's RSet will not be freed
829 // up. The assumption is that this will be done later.
830 void free_region(HeapRegion* hr,
831 size_t* pre_used,
832 FreeRegionList* free_list,
833 bool par);
834
835 // Frees a humongous region by collapsing it into individual regions
836 // and calling free_region() for each of them. The freed regions
837 // will be added to the free list that's passed as a parameter (this
838 // is usually a local list which will be appended to the master free
839 // list later). The used bytes of freed regions are accumulated in
840 // pre_used. If par is true, the region's RSet will not be freed
841 // up. The assumption is that this will be done later.
842 void free_humongous_region(HeapRegion* hr,
843 size_t* pre_used,
844 FreeRegionList* free_list,
845 HumongousRegionSet* humongous_proxy_set,
846 bool par);
847
848 // Notifies all the necessary spaces that the committed space has
849 // been updated (either expanded or shrunk). It should be called
850 // after _g1_storage is updated.
851 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
852
853 // The concurrent marker (and the thread it runs in.)
854 ConcurrentMark* _cm;
855 ConcurrentMarkThread* _cmThread;
856 bool _mark_in_progress;
857
858 // The concurrent refiner.
859 ConcurrentG1Refine* _cg1r;
860
861 // The parallel task queues
862 RefToScanQueueSet *_task_queues;
863
864 // True iff a evacuation has failed in the current collection.
865 bool _evacuation_failed;
866
867 // Set the attribute indicating whether evacuation has failed in the
868 // current collection.
869 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
870
871 // Failed evacuations cause some logical from-space objects to have
872 // forwarding pointers to themselves. Reset them.
873 void remove_self_forwarding_pointers();
874
875 // Together, these store an object with a preserved mark, and its mark value.
876 Stack<oop, mtGC> _objs_with_preserved_marks;
877 Stack<markOop, mtGC> _preserved_marks_of_objs;
878
879 // Preserve the mark of "obj", if necessary, in preparation for its mark
880 // word being overwritten with a self-forwarding-pointer.
881 void preserve_mark_if_necessary(oop obj, markOop m);
882
883 // The stack of evac-failure objects left to be scanned.
884 GrowableArray<oop>* _evac_failure_scan_stack;
885 // The closure to apply to evac-failure objects.
886
887 OopsInHeapRegionClosure* _evac_failure_closure;
888 // Set the field above.
889 void
890 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
891 _evac_failure_closure = evac_failure_closure;
892 }
893
894 // Push "obj" on the scan stack.
895 void push_on_evac_failure_scan_stack(oop obj);
896 // Process scan stack entries until the stack is empty.
897 void drain_evac_failure_scan_stack();
898 // True iff an invocation of "drain_scan_stack" is in progress; to
899 // prevent unnecessary recursion.
900 bool _drain_in_progress;
901
902 // Do any necessary initialization for evacuation-failure handling.
903 // "cl" is the closure that will be used to process evac-failure
904 // objects.
905 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
906 // Do any necessary cleanup for evacuation-failure handling data
907 // structures.
908 void finalize_for_evac_failure();
909
910 // An attempt to evacuate "obj" has failed; take necessary steps.
911 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
912 void handle_evacuation_failure_common(oop obj, markOop m);
913
914 #ifndef PRODUCT
915 // Support for forcing evacuation failures. Analogous to
916 // PromotionFailureALot for the other collectors.
917
918 // Records whether G1EvacuationFailureALot should be in effect
919 // for the current GC
920 bool _evacuation_failure_alot_for_current_gc;
921
922 // Used to record the GC number for interval checking when
923 // determining whether G1EvaucationFailureALot is in effect
924 // for the current GC.
925 size_t _evacuation_failure_alot_gc_number;
926
927 // Count of the number of evacuations between failures.
928 volatile size_t _evacuation_failure_alot_count;
929
930 // Set whether G1EvacuationFailureALot should be in effect
931 // for the current GC (based upon the type of GC and which
932 // command line flags are set);
933 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
934 bool during_initial_mark,
935 bool during_marking);
936
937 inline void set_evacuation_failure_alot_for_current_gc();
938
939 // Return true if it's time to cause an evacuation failure.
940 inline bool evacuation_should_fail();
941
942 // Reset the G1EvacuationFailureALot counters. Should be called at
943 // the end of an evacuation pause in which an evacuation failure ocurred.
944 inline void reset_evacuation_should_fail();
945 #endif // !PRODUCT
946
947 // ("Weak") Reference processing support.
948 //
949 // G1 has 2 instances of the referece processor class. One
950 // (_ref_processor_cm) handles reference object discovery
951 // and subsequent processing during concurrent marking cycles.
952 //
953 // The other (_ref_processor_stw) handles reference object
954 // discovery and processing during full GCs and incremental
955 // evacuation pauses.
956 //
957 // During an incremental pause, reference discovery will be
958 // temporarily disabled for _ref_processor_cm and will be
959 // enabled for _ref_processor_stw. At the end of the evacuation
960 // pause references discovered by _ref_processor_stw will be
961 // processed and discovery will be disabled. The previous
962 // setting for reference object discovery for _ref_processor_cm
963 // will be re-instated.
964 //
965 // At the start of marking:
966 // * Discovery by the CM ref processor is verified to be inactive
967 // and it's discovered lists are empty.
968 // * Discovery by the CM ref processor is then enabled.
969 //
970 // At the end of marking:
971 // * Any references on the CM ref processor's discovered
972 // lists are processed (possibly MT).
973 //
974 // At the start of full GC we:
975 // * Disable discovery by the CM ref processor and
976 // empty CM ref processor's discovered lists
977 // (without processing any entries).
978 // * Verify that the STW ref processor is inactive and it's
979 // discovered lists are empty.
980 // * Temporarily set STW ref processor discovery as single threaded.
981 // * Temporarily clear the STW ref processor's _is_alive_non_header
982 // field.
983 // * Finally enable discovery by the STW ref processor.
984 //
985 // The STW ref processor is used to record any discovered
986 // references during the full GC.
987 //
988 // At the end of a full GC we:
989 // * Enqueue any reference objects discovered by the STW ref processor
990 // that have non-live referents. This has the side-effect of
991 // making the STW ref processor inactive by disabling discovery.
992 // * Verify that the CM ref processor is still inactive
993 // and no references have been placed on it's discovered
994 // lists (also checked as a precondition during initial marking).
995
996 // The (stw) reference processor...
997 ReferenceProcessor* _ref_processor_stw;
998
999 // During reference object discovery, the _is_alive_non_header
1000 // closure (if non-null) is applied to the referent object to
1001 // determine whether the referent is live. If so then the
1002 // reference object does not need to be 'discovered' and can
1003 // be treated as a regular oop. This has the benefit of reducing
1004 // the number of 'discovered' reference objects that need to
1005 // be processed.
1006 //
1007 // Instance of the is_alive closure for embedding into the
1008 // STW reference processor as the _is_alive_non_header field.
1009 // Supplying a value for the _is_alive_non_header field is
1010 // optional but doing so prevents unnecessary additions to
1011 // the discovered lists during reference discovery.
1012 G1STWIsAliveClosure _is_alive_closure_stw;
1013
1014 // The (concurrent marking) reference processor...
1015 ReferenceProcessor* _ref_processor_cm;
1016
1017 // Instance of the concurrent mark is_alive closure for embedding
1018 // into the Concurrent Marking reference processor as the
1019 // _is_alive_non_header field. Supplying a value for the
1020 // _is_alive_non_header field is optional but doing so prevents
1021 // unnecessary additions to the discovered lists during reference
1022 // discovery.
1023 G1CMIsAliveClosure _is_alive_closure_cm;
1024
1025 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1026 HeapRegion** _worker_cset_start_region;
1027
1028 // Time stamp to validate the regions recorded in the cache
1029 // used by G1CollectedHeap::start_cset_region_for_worker().
1030 // The heap region entry for a given worker is valid iff
1031 // the associated time stamp value matches the current value
1032 // of G1CollectedHeap::_gc_time_stamp.
1033 unsigned int* _worker_cset_start_region_time_stamp;
1034
1035 enum G1H_process_strong_roots_tasks {
1036 G1H_PS_filter_satb_buffers,
1037 G1H_PS_refProcessor_oops_do,
1038 // Leave this one last.
1039 G1H_PS_NumElements
1040 };
1041
1042 SubTasksDone* _process_strong_tasks;
1043
1044 volatile bool _free_regions_coming;
1045
1046 public:
1047
1048 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1049
1050 void set_refine_cte_cl_concurrency(bool concurrent);
1051
1052 RefToScanQueue *task_queue(int i) const;
1053
1054 // A set of cards where updates happened during the GC
1055 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1056
1057 // A DirtyCardQueueSet that is used to hold cards that contain
1058 // references into the current collection set. This is used to
1059 // update the remembered sets of the regions in the collection
1060 // set in the event of an evacuation failure.
1061 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1062 { return _into_cset_dirty_card_queue_set; }
1063
1064 // Create a G1CollectedHeap with the specified policy.
1065 // Must call the initialize method afterwards.
1066 // May not return if something goes wrong.
1067 G1CollectedHeap(G1CollectorPolicy* policy);
1068
1069 // Initialize the G1CollectedHeap to have the initial and
1070 // maximum sizes and remembered and barrier sets
1071 // specified by the policy object.
1072 jint initialize();
1073
1074 // Initialize weak reference processing.
1075 virtual void ref_processing_init();
1076
1077 void set_par_threads(uint t) {
1078 SharedHeap::set_par_threads(t);
1079 // Done in SharedHeap but oddly there are
1080 // two _process_strong_tasks's in a G1CollectedHeap
1081 // so do it here too.
1082 _process_strong_tasks->set_n_threads(t);
1083 }
1084
1085 // Set _n_par_threads according to a policy TBD.
1086 void set_par_threads();
1087
1088 void set_n_termination(int t) {
1089 _process_strong_tasks->set_n_threads(t);
1090 }
1091
1092 virtual CollectedHeap::Name kind() const {
1093 return CollectedHeap::G1CollectedHeap;
1094 }
1095
1096 // The current policy object for the collector.
1097 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1098
1099 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1100
1101 // Adaptive size policy. No such thing for g1.
1102 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1103
1104 // The rem set and barrier set.
1105 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1106 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1107
1108 unsigned get_gc_time_stamp() {
1109 return _gc_time_stamp;
1110 }
1111
1112 void reset_gc_time_stamp() {
1113 _gc_time_stamp = 0;
1114 OrderAccess::fence();
1115 // Clear the cached CSet starting regions and time stamps.
1116 // Their validity is dependent on the GC timestamp.
1117 clear_cset_start_regions();
1118 }
1119
1120 void check_gc_time_stamps() PRODUCT_RETURN;
1121
1122 void increment_gc_time_stamp() {
1123 ++_gc_time_stamp;
1124 OrderAccess::fence();
1125 }
1126
1127 // Reset the given region's GC timestamp. If it's starts humongous,
1128 // also reset the GC timestamp of its corresponding
1129 // continues humongous regions too.
1130 void reset_gc_time_stamps(HeapRegion* hr);
1131
1132 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1133 DirtyCardQueue* into_cset_dcq,
1134 bool concurrent, int worker_i);
1135
1136 // The shared block offset table array.
1137 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1138
1139 // Reference Processing accessors
1140
1141 // The STW reference processor....
1142 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1143
1144 // The Concurent Marking reference processor...
1145 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1146
1147 virtual size_t capacity() const;
1148 virtual size_t used() const;
1149 // This should be called when we're not holding the heap lock. The
1150 // result might be a bit inaccurate.
1151 size_t used_unlocked() const;
1152 size_t recalculate_used() const;
1153
1154 // These virtual functions do the actual allocation.
1155 // Some heaps may offer a contiguous region for shared non-blocking
1156 // allocation, via inlined code (by exporting the address of the top and
1157 // end fields defining the extent of the contiguous allocation region.)
1158 // But G1CollectedHeap doesn't yet support this.
1159
1160 // Return an estimate of the maximum allocation that could be performed
1161 // without triggering any collection or expansion activity. In a
1162 // generational collector, for example, this is probably the largest
1163 // allocation that could be supported (without expansion) in the youngest
1164 // generation. It is "unsafe" because no locks are taken; the result
1165 // should be treated as an approximation, not a guarantee, for use in
1166 // heuristic resizing decisions.
1167 virtual size_t unsafe_max_alloc();
1168
1169 virtual bool is_maximal_no_gc() const {
1170 return _g1_storage.uncommitted_size() == 0;
1171 }
1172
1173 // The total number of regions in the heap.
1174 uint n_regions() { return _hrs.length(); }
1175
1176 // The max number of regions in the heap.
1177 uint max_regions() { return _hrs.max_length(); }
1178
1179 // The number of regions that are completely free.
1180 uint free_regions() { return _free_list.length(); }
1181
1182 // The number of regions that are not completely free.
1183 uint used_regions() { return n_regions() - free_regions(); }
1184
1185 // The number of regions available for "regular" expansion.
1186 uint expansion_regions() { return _expansion_regions; }
1187
1188 // Factory method for HeapRegion instances. It will return NULL if
1189 // the allocation fails.
1190 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1191
1192 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1193 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1194 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1195 void verify_dirty_young_regions() PRODUCT_RETURN;
1196
1197 // verify_region_sets() performs verification over the region
1198 // lists. It will be compiled in the product code to be used when
1199 // necessary (i.e., during heap verification).
1200 void verify_region_sets();
1201
1202 // verify_region_sets_optional() is planted in the code for
1203 // list verification in non-product builds (and it can be enabled in
1204 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1205 #if HEAP_REGION_SET_FORCE_VERIFY
1206 void verify_region_sets_optional() {
1207 verify_region_sets();
1208 }
1209 #else // HEAP_REGION_SET_FORCE_VERIFY
1210 void verify_region_sets_optional() { }
1211 #endif // HEAP_REGION_SET_FORCE_VERIFY
1212
1213 #ifdef ASSERT
1214 bool is_on_master_free_list(HeapRegion* hr) {
1215 return hr->containing_set() == &_free_list;
1216 }
1217
1218 bool is_in_humongous_set(HeapRegion* hr) {
1219 return hr->containing_set() == &_humongous_set;
1220 }
1221 #endif // ASSERT
1222
1223 // Wrapper for the region list operations that can be called from
1224 // methods outside this class.
1225
1226 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1227 _secondary_free_list.add_as_tail(list);
1228 }
1229
1230 void append_secondary_free_list() {
1231 _free_list.add_as_head(&_secondary_free_list);
1232 }
1233
1234 void append_secondary_free_list_if_not_empty_with_lock() {
1235 // If the secondary free list looks empty there's no reason to
1236 // take the lock and then try to append it.
1237 if (!_secondary_free_list.is_empty()) {
1238 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1239 append_secondary_free_list();
1240 }
1241 }
1242
1243 void old_set_remove(HeapRegion* hr) {
1244 _old_set.remove(hr);
1245 }
1246
1247 size_t non_young_capacity_bytes() {
1248 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1249 }
1250
1251 void set_free_regions_coming();
1252 void reset_free_regions_coming();
1253 bool free_regions_coming() { return _free_regions_coming; }
1254 void wait_while_free_regions_coming();
1255
1256 // Determine whether the given region is one that we are using as an
1257 // old GC alloc region.
1258 bool is_old_gc_alloc_region(HeapRegion* hr) {
1259 return hr == _retained_old_gc_alloc_region;
1260 }
1261
1262 // Perform a collection of the heap; intended for use in implementing
1263 // "System.gc". This probably implies as full a collection as the
1264 // "CollectedHeap" supports.
1265 virtual void collect(GCCause::Cause cause);
1266
1267 // The same as above but assume that the caller holds the Heap_lock.
1268 void collect_locked(GCCause::Cause cause);
1269
1270 // True iff a evacuation has failed in the most-recent collection.
1271 bool evacuation_failed() { return _evacuation_failed; }
1272
1273 // It will free a region if it has allocated objects in it that are
1274 // all dead. It calls either free_region() or
1275 // free_humongous_region() depending on the type of the region that
1276 // is passed to it.
1277 void free_region_if_empty(HeapRegion* hr,
1278 size_t* pre_used,
1279 FreeRegionList* free_list,
1280 OldRegionSet* old_proxy_set,
1281 HumongousRegionSet* humongous_proxy_set,
1282 HRRSCleanupTask* hrrs_cleanup_task,
1283 bool par);
1284
1285 // It appends the free list to the master free list and updates the
1286 // master humongous list according to the contents of the proxy
1287 // list. It also adjusts the total used bytes according to pre_used
1288 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1289 void update_sets_after_freeing_regions(size_t pre_used,
1290 FreeRegionList* free_list,
1291 OldRegionSet* old_proxy_set,
1292 HumongousRegionSet* humongous_proxy_set,
1293 bool par);
1294
1295 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1296 virtual bool is_in(const void* p) const;
1297
1298 // Return "TRUE" iff the given object address is within the collection
1299 // set.
1300 inline bool obj_in_cs(oop obj);
1301
1302 // Return "TRUE" iff the given object address is in the reserved
1303 // region of g1.
1304 bool is_in_g1_reserved(const void* p) const {
1305 return _g1_reserved.contains(p);
1306 }
1307
1308 // Returns a MemRegion that corresponds to the space that has been
1309 // reserved for the heap
1310 MemRegion g1_reserved() {
1311 return _g1_reserved;
1312 }
1313
1314 // Returns a MemRegion that corresponds to the space that has been
1315 // committed in the heap
1316 MemRegion g1_committed() {
1317 return _g1_committed;
1318 }
1319
1320 virtual bool is_in_closed_subset(const void* p) const;
1321
1322 // This resets the card table to all zeros. It is used after
1323 // a collection pause which used the card table to claim cards.
1324 void cleanUpCardTable();
1325
1326 // Iteration functions.
1327
1328 // Iterate over all the ref-containing fields of all objects, calling
1329 // "cl.do_oop" on each.
1330 virtual void oop_iterate(ExtendedOopClosure* cl);
1331
1332 // Same as above, restricted to a memory region.
1333 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1334
1335 // Iterate over all objects, calling "cl.do_object" on each.
1336 virtual void object_iterate(ObjectClosure* cl);
1337
1338 virtual void safe_object_iterate(ObjectClosure* cl) {
1339 object_iterate(cl);
1340 }
1341
1342 // Iterate over all objects allocated since the last collection, calling
1343 // "cl.do_object" on each. The heap must have been initialized properly
1344 // to support this function, or else this call will fail.
1345 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1346
1347 // Iterate over all spaces in use in the heap, in ascending address order.
1348 virtual void space_iterate(SpaceClosure* cl);
1349
1350 // Iterate over heap regions, in address order, terminating the
1351 // iteration early if the "doHeapRegion" method returns "true".
1352 void heap_region_iterate(HeapRegionClosure* blk) const;
1353
1354 // Return the region with the given index. It assumes the index is valid.
1355 HeapRegion* region_at(uint index) const { return _hrs.at(index); }
1356
1357 // Divide the heap region sequence into "chunks" of some size (the number
1358 // of regions divided by the number of parallel threads times some
1359 // overpartition factor, currently 4). Assumes that this will be called
1360 // in parallel by ParallelGCThreads worker threads with discinct worker
1361 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1362 // calls will use the same "claim_value", and that that claim value is
1363 // different from the claim_value of any heap region before the start of
1364 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1365 // attempting to claim the first region in each chunk, and, if
1366 // successful, applying the closure to each region in the chunk (and
1367 // setting the claim value of the second and subsequent regions of the
1368 // chunk.) For now requires that "doHeapRegion" always returns "false",
1369 // i.e., that a closure never attempt to abort a traversal.
1370 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1371 uint worker,
1372 uint no_of_par_workers,
1373 jint claim_value);
1374
1375 // It resets all the region claim values to the default.
1376 void reset_heap_region_claim_values();
1377
1378 // Resets the claim values of regions in the current
1379 // collection set to the default.
1380 void reset_cset_heap_region_claim_values();
1381
1382 #ifdef ASSERT
1383 bool check_heap_region_claim_values(jint claim_value);
1384
1385 // Same as the routine above but only checks regions in the
1386 // current collection set.
1387 bool check_cset_heap_region_claim_values(jint claim_value);
1388 #endif // ASSERT
1389
1390 // Clear the cached cset start regions and (more importantly)
1391 // the time stamps. Called when we reset the GC time stamp.
1392 void clear_cset_start_regions();
1393
1394 // Given the id of a worker, obtain or calculate a suitable
1395 // starting region for iterating over the current collection set.
1396 HeapRegion* start_cset_region_for_worker(int worker_i);
1397
1398 // This is a convenience method that is used by the
1399 // HeapRegionIterator classes to calculate the starting region for
1400 // each worker so that they do not all start from the same region.
1401 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1402
1403 // Iterate over the regions (if any) in the current collection set.
1404 void collection_set_iterate(HeapRegionClosure* blk);
1405
1406 // As above but starting from region r
1407 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1408
1409 // Returns the first (lowest address) compactible space in the heap.
1410 virtual CompactibleSpace* first_compactible_space();
1411
1412 // A CollectedHeap will contain some number of spaces. This finds the
1413 // space containing a given address, or else returns NULL.
1414 virtual Space* space_containing(const void* addr) const;
1415
1416 // A G1CollectedHeap will contain some number of heap regions. This
1417 // finds the region containing a given address, or else returns NULL.
1418 template <class T>
1419 inline HeapRegion* heap_region_containing(const T addr) const;
1420
1421 // Like the above, but requires "addr" to be in the heap (to avoid a
1422 // null-check), and unlike the above, may return an continuing humongous
1423 // region.
1424 template <class T>
1425 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1426
1427 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1428 // each address in the (reserved) heap is a member of exactly
1429 // one block. The defining characteristic of a block is that it is
1430 // possible to find its size, and thus to progress forward to the next
1431 // block. (Blocks may be of different sizes.) Thus, blocks may
1432 // represent Java objects, or they might be free blocks in a
1433 // free-list-based heap (or subheap), as long as the two kinds are
1434 // distinguishable and the size of each is determinable.
1435
1436 // Returns the address of the start of the "block" that contains the
1437 // address "addr". We say "blocks" instead of "object" since some heaps
1438 // may not pack objects densely; a chunk may either be an object or a
1439 // non-object.
1440 virtual HeapWord* block_start(const void* addr) const;
1441
1442 // Requires "addr" to be the start of a chunk, and returns its size.
1443 // "addr + size" is required to be the start of a new chunk, or the end
1444 // of the active area of the heap.
1445 virtual size_t block_size(const HeapWord* addr) const;
1446
1447 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1448 // the block is an object.
1449 virtual bool block_is_obj(const HeapWord* addr) const;
1450
1451 // Does this heap support heap inspection? (+PrintClassHistogram)
1452 virtual bool supports_heap_inspection() const { return true; }
1453
1454 // Section on thread-local allocation buffers (TLABs)
1455 // See CollectedHeap for semantics.
1456
1457 virtual bool supports_tlab_allocation() const;
1458 virtual size_t tlab_capacity(Thread* thr) const;
1459 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1460
1461 // Can a compiler initialize a new object without store barriers?
1462 // This permission only extends from the creation of a new object
1463 // via a TLAB up to the first subsequent safepoint. If such permission
1464 // is granted for this heap type, the compiler promises to call
1465 // defer_store_barrier() below on any slow path allocation of
1466 // a new object for which such initializing store barriers will
1467 // have been elided. G1, like CMS, allows this, but should be
1468 // ready to provide a compensating write barrier as necessary
1469 // if that storage came out of a non-young region. The efficiency
1470 // of this implementation depends crucially on being able to
1471 // answer very efficiently in constant time whether a piece of
1472 // storage in the heap comes from a young region or not.
1473 // See ReduceInitialCardMarks.
1474 virtual bool can_elide_tlab_store_barriers() const {
1475 return true;
1476 }
1477
1478 virtual bool card_mark_must_follow_store() const {
1479 return true;
1480 }
1481
1482 bool is_in_young(const oop obj) {
1483 HeapRegion* hr = heap_region_containing(obj);
1484 return hr != NULL && hr->is_young();
1485 }
1486
1487 #ifdef ASSERT
1488 virtual bool is_in_partial_collection(const void* p);
1489 #endif
1490
1491 virtual bool is_scavengable(const void* addr);
1492
1493 // We don't need barriers for initializing stores to objects
1494 // in the young gen: for the SATB pre-barrier, there is no
1495 // pre-value that needs to be remembered; for the remembered-set
1496 // update logging post-barrier, we don't maintain remembered set
1497 // information for young gen objects.
1498 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1499 return is_in_young(new_obj);
1500 }
1501
1502 // Returns "true" iff the given word_size is "very large".
1503 static bool isHumongous(size_t word_size) {
1504 // Note this has to be strictly greater-than as the TLABs
1505 // are capped at the humongous thresold and we want to
1506 // ensure that we don't try to allocate a TLAB as
1507 // humongous and that we don't allocate a humongous
1508 // object in a TLAB.
1509 return word_size > _humongous_object_threshold_in_words;
1510 }
1511
1512 // Update mod union table with the set of dirty cards.
1513 void updateModUnion();
1514
1515 // Set the mod union bits corresponding to the given memRegion. Note
1516 // that this is always a safe operation, since it doesn't clear any
1517 // bits.
1518 void markModUnionRange(MemRegion mr);
1519
1520 // Records the fact that a marking phase is no longer in progress.
1521 void set_marking_complete() {
1522 _mark_in_progress = false;
1523 }
1524 void set_marking_started() {
1525 _mark_in_progress = true;
1526 }
1527 bool mark_in_progress() {
1528 return _mark_in_progress;
1529 }
1530
1531 // Print the maximum heap capacity.
1532 virtual size_t max_capacity() const;
1533
1534 virtual jlong millis_since_last_gc();
1535
1536 // Perform any cleanup actions necessary before allowing a verification.
1537 virtual void prepare_for_verify();
1538
1539 // Perform verification.
1540
1541 // vo == UsePrevMarking -> use "prev" marking information,
1542 // vo == UseNextMarking -> use "next" marking information
1543 // vo == UseMarkWord -> use the mark word in the object header
1544 //
1545 // NOTE: Only the "prev" marking information is guaranteed to be
1546 // consistent most of the time, so most calls to this should use
1547 // vo == UsePrevMarking.
1548 // Currently, there is only one case where this is called with
1549 // vo == UseNextMarking, which is to verify the "next" marking
1550 // information at the end of remark.
1551 // Currently there is only one place where this is called with
1552 // vo == UseMarkWord, which is to verify the marking during a
1553 // full GC.
1554 void verify(bool silent, VerifyOption vo);
1555
1556 // Override; it uses the "prev" marking information
1557 virtual void verify(bool silent);
1558 virtual void print_on(outputStream* st) const;
1559 virtual void print_extended_on(outputStream* st) const;
1560 virtual void print_on_error(outputStream* st) const;
1561
1562 virtual void print_gc_threads_on(outputStream* st) const;
1563 virtual void gc_threads_do(ThreadClosure* tc) const;
1564
1565 // Override
1566 void print_tracing_info() const;
1567
1568 // The following two methods are helpful for debugging RSet issues.
1569 void print_cset_rsets() PRODUCT_RETURN;
1570 void print_all_rsets() PRODUCT_RETURN;
1571
1572 // Convenience function to be used in situations where the heap type can be
1573 // asserted to be this type.
1574 static G1CollectedHeap* heap();
1575
1576 void set_region_short_lived_locked(HeapRegion* hr);
1577 // add appropriate methods for any other surv rate groups
1578
1579 YoungList* young_list() { return _young_list; }
1580
1581 // debugging
1582 bool check_young_list_well_formed() {
1583 return _young_list->check_list_well_formed();
1584 }
1585
1586 bool check_young_list_empty(bool check_heap,
1587 bool check_sample = true);
1588
1589 // *** Stuff related to concurrent marking. It's not clear to me that so
1590 // many of these need to be public.
1591
1592 // The functions below are helper functions that a subclass of
1593 // "CollectedHeap" can use in the implementation of its virtual
1594 // functions.
1595 // This performs a concurrent marking of the live objects in a
1596 // bitmap off to the side.
1597 void doConcurrentMark();
1598
1599 bool isMarkedPrev(oop obj) const;
1600 bool isMarkedNext(oop obj) const;
1601
1602 // Determine if an object is dead, given the object and also
1603 // the region to which the object belongs. An object is dead
1604 // iff a) it was not allocated since the last mark and b) it
1605 // is not marked.
1606
1607 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1608 return
1609 !hr->obj_allocated_since_prev_marking(obj) &&
1610 !isMarkedPrev(obj);
1611 }
1612
1613 // This function returns true when an object has been
1614 // around since the previous marking and hasn't yet
1615 // been marked during this marking.
1616
1617 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1618 return
1619 !hr->obj_allocated_since_next_marking(obj) &&
1620 !isMarkedNext(obj);
1621 }
1622
1623 // Determine if an object is dead, given only the object itself.
1624 // This will find the region to which the object belongs and
1625 // then call the region version of the same function.
1626
1627 // Added if it is NULL it isn't dead.
1628
1629 bool is_obj_dead(const oop obj) const {
1630 const HeapRegion* hr = heap_region_containing(obj);
1631 if (hr == NULL) {
1632 if (obj == NULL) return false;
1633 else return true;
1634 }
1635 else return is_obj_dead(obj, hr);
1636 }
1637
1638 bool is_obj_ill(const oop obj) const {
1639 const HeapRegion* hr = heap_region_containing(obj);
1640 if (hr == NULL) {
1641 if (obj == NULL) return false;
1642 else return true;
1643 }
1644 else return is_obj_ill(obj, hr);
1645 }
1646
1647 // The methods below are here for convenience and dispatch the
1648 // appropriate method depending on value of the given VerifyOption
1649 // parameter. The options for that parameter are:
1650 //
1651 // vo == UsePrevMarking -> use "prev" marking information,
1652 // vo == UseNextMarking -> use "next" marking information,
1653 // vo == UseMarkWord -> use mark word from object header
1654
1655 bool is_obj_dead_cond(const oop obj,
1656 const HeapRegion* hr,
1657 const VerifyOption vo) const {
1658 switch (vo) {
1659 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
1660 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
1661 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1662 default: ShouldNotReachHere();
1663 }
1664 return false; // keep some compilers happy
1665 }
1666
1667 bool is_obj_dead_cond(const oop obj,
1668 const VerifyOption vo) const {
1669 switch (vo) {
1670 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
1671 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
1672 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
1673 default: ShouldNotReachHere();
1674 }
1675 return false; // keep some compilers happy
1676 }
1677
1678 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1679 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1680 bool is_marked(oop obj, VerifyOption vo);
1681 const char* top_at_mark_start_str(VerifyOption vo);
1682
1683 // The following is just to alert the verification code
1684 // that a full collection has occurred and that the
1685 // remembered sets are no longer up to date.
1686 bool _full_collection;
1687 void set_full_collection() { _full_collection = true;}
1688 void clear_full_collection() {_full_collection = false;}
1689 bool full_collection() {return _full_collection;}
1690
1691 ConcurrentMark* concurrent_mark() const { return _cm; }
1692 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1693
1694 // The dirty cards region list is used to record a subset of regions
1695 // whose cards need clearing. The list if populated during the
1696 // remembered set scanning and drained during the card table
1697 // cleanup. Although the methods are reentrant, population/draining
1698 // phases must not overlap. For synchronization purposes the last
1699 // element on the list points to itself.
1700 HeapRegion* _dirty_cards_region_list;
1701 void push_dirty_cards_region(HeapRegion* hr);
1702 HeapRegion* pop_dirty_cards_region();
1703
1704 public:
1705 void stop_conc_gc_threads();
1706
1707 size_t pending_card_num();
1708 size_t cards_scanned();
1709
1710 protected:
1711 size_t _max_heap_capacity;
1712 };
1713
1714 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1715 private:
1716 bool _retired;
1717
1718 public:
1719 G1ParGCAllocBuffer(size_t gclab_word_size);
1720
1721 void set_buf(HeapWord* buf) {
1722 ParGCAllocBuffer::set_buf(buf);
1723 _retired = false;
1724 }
1725
1726 void retire(bool end_of_gc, bool retain) {
1727 if (_retired)
1728 return;
1729 ParGCAllocBuffer::retire(end_of_gc, retain);
1730 _retired = true;
1731 }
1732
1733 bool is_retired() {
1734 return _retired;
1735 }
1736 };
1737
1738 class G1ParGCAllocBufferContainer {
1739 protected:
1740 enum GCAllocPriority {
1741 GCAllocPriorityStart = 0,
1742 GCAllocPriority1 = GCAllocPriorityStart,
1743 GCAllocPriority2 = GCAllocPriorityStart + 1,
1744 GCAllocPriorityCount = GCAllocPriorityStart + 2
1745 };
1746 G1ParGCAllocBuffer* _priority_buffer[GCAllocPriorityCount];
1747
1748 public:
1749 G1ParGCAllocBufferContainer(size_t gclab_word_size) {
1750 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1751 _priority_buffer[pr] = new G1ParGCAllocBuffer(gclab_word_size);
1752 }
1753 }
1754
1755 ~G1ParGCAllocBufferContainer() {
1756 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1757 assert(_priority_buffer[pr]->is_retired(), "alloc buffers should all retire at this point.");
1758 delete _priority_buffer[pr];
1759 }
1760 }
1761
1762 HeapWord* allocate(size_t word_sz) {
1763 HeapWord* obj;
1764 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1765 obj = _priority_buffer[pr]->allocate(word_sz);
1766 if (obj != NULL) return obj;
1767 }
1768 return obj;
1769 }
1770
1771 bool contains(void* addr) {
1772 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1773 if (_priority_buffer[pr]->contains(addr)) return true;
1774 }
1775 return false;
1776 }
1777
1778 void undo_allocation(HeapWord* obj, size_t word_sz) {
1779 bool finish_undo;
1780 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1781 if (_priority_buffer[pr]->contains(obj)) {
1782 _priority_buffer[pr]->undo_allocation(obj, word_sz);
1783 finish_undo = true;
1784 }
1785 }
1786 if (!finish_undo) ShouldNotReachHere();
1787 }
1788
1789 size_t words_remaining() {
1790 size_t result = 0;
1791 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1792 result += _priority_buffer[pr]->words_remaining();
1793 }
1794 return result;
1795 }
1796
1797 size_t words_remaining_in_priority1_buffer() {
1798 G1ParGCAllocBuffer* retired = _priority_buffer[GCAllocPriority1];
1799 return retired->words_remaining();
1800 }
1801
1802 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) {
1803 for (int pr = GCAllocPriorityStart; pr < GCAllocPriorityCount; ++pr) {
1804 _priority_buffer[pr]->flush_stats_and_retire(stats, end_of_gc, retain);
1805 }
1806 }
1807
1808 void retire_and_set_buf(bool end_of_gc, bool retain, HeapWord* buf, size_t word_sz) {
1809 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[GCAllocPriority1];
1810 retired_and_set->retire(end_of_gc, retain);
1811 retired_and_set->set_buf(buf);
1812 retired_and_set->set_word_size(word_sz);
1813 adjust_priority_order();
1814 }
1815
1816 private:
1817 void adjust_priority_order() {
1818 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[GCAllocPriority1];
1819
1820 int last = GCAllocPriorityCount - 1;
1821 for (int pr = GCAllocPriorityStart; pr < last; ++pr) {
1822 _priority_buffer[pr] = _priority_buffer[pr + 1];
1823 }
1824 _priority_buffer[last] = retired_and_set;
1825 }
1826 };
1827
1828 class G1ParScanThreadState : public StackObj {
1829 protected:
1830 G1CollectedHeap* _g1h;
1831 RefToScanQueue* _refs;
1832 DirtyCardQueue _dcq;
1833 CardTableModRefBS* _ct_bs;
1834 G1RemSet* _g1_rem;
1835
1836 G1ParGCAllocBufferContainer _surviving_alloc_buffer;
1837 G1ParGCAllocBufferContainer _tenured_alloc_buffer;
1838 G1ParGCAllocBufferContainer* _alloc_buffers[GCAllocPurposeCount];
1839 ageTable _age_table;
1840
1841 size_t _alloc_buffer_waste;
1842 size_t _undo_waste;
1843
1844 OopsInHeapRegionClosure* _evac_failure_cl;
1845 G1ParScanHeapEvacClosure* _evac_cl;
1846 G1ParScanPartialArrayClosure* _partial_scan_cl;
1847
1848 int _hash_seed;
1849 uint _queue_num;
1850
1851 size_t _term_attempts;
1852
1853 double _start;
1854 double _start_strong_roots;
1855 double _strong_roots_time;
1856 double _start_term;
1857 double _term_time;
1858
1859 // Map from young-age-index (0 == not young, 1 is youngest) to
1860 // surviving words. base is what we get back from the malloc call
1861 size_t* _surviving_young_words_base;
1862 // this points into the array, as we use the first few entries for padding
1863 size_t* _surviving_young_words;
1864
1865 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1866
1867 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1868
1869 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1870
1871 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1872 CardTableModRefBS* ctbs() { return _ct_bs; }
1873
1874 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1875 if (!from->is_survivor()) {
1876 _g1_rem->par_write_ref(from, p, tid);
1877 }
1878 }
1879
1880 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1881 // If the new value of the field points to the same region or
1882 // is the to-space, we don't need to include it in the Rset updates.
1883 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1884 size_t card_index = ctbs()->index_for(p);
1885 // If the card hasn't been added to the buffer, do it.
1886 if (ctbs()->mark_card_deferred(card_index)) {
1887 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1888 }
1889 }
1890 }
1891
1892 public:
1893 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1894
1895 ~G1ParScanThreadState() {
1896 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
1897 }
1898
1899 RefToScanQueue* refs() { return _refs; }
1900 ageTable* age_table() { return &_age_table; }
1901
1902 G1ParGCAllocBufferContainer* alloc_buffer(GCAllocPurpose purpose) {
1903 return _alloc_buffers[purpose];
1904 }
1905
1906 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1907 size_t undo_waste() const { return _undo_waste; }
1908
1909 #ifdef ASSERT
1910 bool verify_ref(narrowOop* ref) const;
1911 bool verify_ref(oop* ref) const;
1912 bool verify_task(StarTask ref) const;
1913 #endif // ASSERT
1914
1915 template <class T> void push_on_queue(T* ref) {
1916 assert(verify_ref(ref), "sanity");
1917 refs()->push(ref);
1918 }
1919
1920 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1921 if (G1DeferredRSUpdate) {
1922 deferred_rs_update(from, p, tid);
1923 } else {
1924 immediate_rs_update(from, p, tid);
1925 }
1926 }
1927
1928 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1929 HeapWord* obj = NULL;
1930 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1931 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1932 G1ParGCAllocBufferContainer* alloc_buf = alloc_buffer(purpose);
1933
1934 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1935 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1936
1937 add_to_alloc_buffer_waste(alloc_buf->words_remaining_in_priority1_buffer());
1938 alloc_buf->retire_and_set_buf(false /* end_of_gc */, false /* retain */,
1939 buf, gclab_word_size);
1940
1941 obj = alloc_buf->allocate(word_sz);
1942 assert(obj != NULL, "buffer was definitely big enough...");
1943 } else {
1944 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1945 }
1946 return obj;
1947 }
1948
1949 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1950 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1951 if (obj != NULL) return obj;
1952 return allocate_slow(purpose, word_sz);
1953 }
1954
1955 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1956 if (alloc_buffer(purpose)->contains(obj)) {
1957 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1958 "should contain whole object");
1959 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1960 } else {
1961 CollectedHeap::fill_with_object(obj, word_sz);
1962 add_to_undo_waste(word_sz);
1963 }
1964 }
1965
1966 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1967 _evac_failure_cl = evac_failure_cl;
1968 }
1969 OopsInHeapRegionClosure* evac_failure_closure() {
1970 return _evac_failure_cl;
1971 }
1972
1973 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1974 _evac_cl = evac_cl;
1975 }
1976
1977 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1978 _partial_scan_cl = partial_scan_cl;
1979 }
1980
1981 int* hash_seed() { return &_hash_seed; }
1982 uint queue_num() { return _queue_num; }
1983
1984 size_t term_attempts() const { return _term_attempts; }
1985 void note_term_attempt() { _term_attempts++; }
1986
1987 void start_strong_roots() {
1988 _start_strong_roots = os::elapsedTime();
1989 }
1990 void end_strong_roots() {
1991 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1992 }
1993 double strong_roots_time() const { return _strong_roots_time; }
1994
1995 void start_term_time() {
1996 note_term_attempt();
1997 _start_term = os::elapsedTime();
1998 }
1999 void end_term_time() {
2000 _term_time += (os::elapsedTime() - _start_term);
2001 }
2002 double term_time() const { return _term_time; }
2003
2004 double elapsed_time() const {
2005 return os::elapsedTime() - _start;
2006 }
2007
2008 static void
2009 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2010 void
2011 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2012
2013 size_t* surviving_young_words() {
2014 // We add on to hide entry 0 which accumulates surviving words for
2015 // age -1 regions (i.e. non-young ones)
2016 return _surviving_young_words;
2017 }
2018
2019 void retire_alloc_buffers() {
2020 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2021 size_t waste = _alloc_buffers[ap]->words_remaining();
2022 add_to_alloc_buffer_waste(waste);
2023 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
2024 true /* end_of_gc */,
2025 false /* retain */);
2026 }
2027 }
2028
2029 template <class T> void deal_with_reference(T* ref_to_scan) {
2030 if (has_partial_array_mask(ref_to_scan)) {
2031 _partial_scan_cl->do_oop_nv(ref_to_scan);
2032 } else {
2033 // Note: we can use "raw" versions of "region_containing" because
2034 // "obj_to_scan" is definitely in the heap, and is not in a
2035 // humongous region.
2036 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2037 _evac_cl->set_region(r);
2038 _evac_cl->do_oop_nv(ref_to_scan);
2039 }
2040 }
2041
2042 void deal_with_reference(StarTask ref) {
2043 assert(verify_task(ref), "sanity");
2044 if (ref.is_narrow()) {
2045 deal_with_reference((narrowOop*)ref);
2046 } else {
2047 deal_with_reference((oop*)ref);
2048 }
2049 }
2050
2051 void trim_queue();
2052 };
2053
2054 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP