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