1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/evacuationInfo.hpp"
30 #include "gc_implementation/g1/g1AllocRegion.hpp"
31 #include "gc_implementation/g1/g1BiasedArray.hpp"
32 #include "gc_implementation/g1/g1HRPrinter.hpp"
33 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
34 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
35 #include "gc_implementation/g1/g1YCTypes.hpp"
36 #include "gc_implementation/g1/heapRegionSeq.hpp"
37 #include "gc_implementation/g1/heapRegionSet.hpp"
38 #include "gc_implementation/shared/hSpaceCounters.hpp"
39 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
40 #include "memory/barrierSet.hpp"
41 #include "memory/memRegion.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "utilities/stack.hpp"
44
45 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
46 // It uses the "Garbage First" heap organization and algorithm, which
47 // may combine concurrent marking with parallel, incremental compaction of
48 // heap subsets that will yield large amounts of garbage.
49
50 // Forward declarations
51 class HeapRegion;
52 class HRRSCleanupTask;
53 class GenerationSpec;
54 class OopsInHeapRegionClosure;
55 class G1KlassScanClosure;
56 class G1ScanHeapEvacClosure;
57 class ObjectClosure;
58 class SpaceClosure;
59 class CompactibleSpaceClosure;
60 class Space;
61 class G1CollectorPolicy;
62 class GenRemSet;
63 class G1RemSet;
64 class HeapRegionRemSetIterator;
65 class ConcurrentMark;
66 class ConcurrentMarkThread;
67 class ConcurrentG1Refine;
68 class ConcurrentGCTimer;
69 class GenerationCounters;
70 class STWGCTimer;
71 class G1NewTracer;
72 class G1OldTracer;
73 class EvacuationFailedInfo;
74 class nmethod;
75 class Ticks;
76
77 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
78 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
79
80 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
81 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
82
83 enum GCAllocPurpose {
84 GCAllocForTenured,
85 GCAllocForSurvived,
86 GCAllocPurposeCount
87 };
88
89 class YoungList : public CHeapObj<mtGC> {
90 private:
91 G1CollectedHeap* _g1h;
92
93 HeapRegion* _head;
94
95 HeapRegion* _survivor_head;
96 HeapRegion* _survivor_tail;
97
98 HeapRegion* _curr;
99
100 uint _length;
101 uint _survivor_length;
102
103 size_t _last_sampled_rs_lengths;
104 size_t _sampled_rs_lengths;
105
106 void empty_list(HeapRegion* list);
107
108 public:
109 YoungList(G1CollectedHeap* g1h);
110
111 void push_region(HeapRegion* hr);
112 void add_survivor_region(HeapRegion* hr);
113
114 void empty_list();
115 bool is_empty() { return _length == 0; }
116 uint length() { return _length; }
117 uint survivor_length() { return _survivor_length; }
118
119 // Currently we do not keep track of the used byte sum for the
120 // young list and the survivors and it'd be quite a lot of work to
121 // do so. When we'll eventually replace the young list with
122 // instances of HeapRegionLinkedList we'll get that for free. So,
123 // we'll report the more accurate information then.
124 size_t eden_used_bytes() {
125 assert(length() >= survivor_length(), "invariant");
126 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
127 }
128 size_t survivor_used_bytes() {
129 return (size_t) survivor_length() * HeapRegion::GrainBytes;
130 }
131
132 void rs_length_sampling_init();
133 bool rs_length_sampling_more();
134 void rs_length_sampling_next();
135
136 void reset_sampled_info() {
137 _last_sampled_rs_lengths = 0;
138 }
139 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
140
141 // for development purposes
142 void reset_auxilary_lists();
143 void clear() { _head = NULL; _length = 0; }
144
145 void clear_survivors() {
146 _survivor_head = NULL;
147 _survivor_tail = NULL;
148 _survivor_length = 0;
149 }
150
151 HeapRegion* first_region() { return _head; }
152 HeapRegion* first_survivor_region() { return _survivor_head; }
153 HeapRegion* last_survivor_region() { return _survivor_tail; }
154
155 // debugging
156 bool check_list_well_formed();
157 bool check_list_empty(bool check_sample = true);
158 void print();
159 };
160
161 class MutatorAllocRegion : public G1AllocRegion {
162 protected:
163 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
164 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
165 public:
166 MutatorAllocRegion()
167 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
168 };
169
170 class SurvivorGCAllocRegion : public G1AllocRegion {
171 protected:
172 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
173 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
174 public:
175 SurvivorGCAllocRegion()
176 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
177 };
178
179 class OldGCAllocRegion : public G1AllocRegion {
180 protected:
181 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
182 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
183 public:
184 OldGCAllocRegion()
185 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
186 };
187
188 // The G1 STW is alive closure.
189 // An instance is embedded into the G1CH and used as the
190 // (optional) _is_alive_non_header closure in the STW
191 // reference processor. It is also extensively used during
192 // reference processing during STW evacuation pauses.
193 class G1STWIsAliveClosure: public BoolObjectClosure {
194 G1CollectedHeap* _g1;
195 public:
196 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
197 bool do_object_b(oop p);
198 };
199
200 // Instances of this class are used for quick tests on whether a reference points
201 // into the collection set. Each of the array's elements denotes whether the
202 // corresponding region is in the collection set.
203 class G1FastCSetBiasedMappedArray : public G1BiasedMappedArray<bool> {
204 protected:
205 bool default_value() const { return false; }
206 public:
207 void clear() { G1BiasedMappedArray<bool>::clear(); }
208 };
209
210 class RefineCardTableEntryClosure;
211
212 class G1CollectedHeap : public SharedHeap {
213 friend class VM_CollectForMetadataAllocation;
214 friend class VM_G1CollectForAllocation;
215 friend class VM_G1CollectFull;
216 friend class VM_G1IncCollectionPause;
217 friend class VMStructs;
218 friend class MutatorAllocRegion;
219 friend class SurvivorGCAllocRegion;
220 friend class OldGCAllocRegion;
221
222 // Closures used in implementation.
223 template <G1Barrier barrier, G1Mark do_mark_object>
224 friend class G1ParCopyClosure;
225 friend class G1IsAliveClosure;
226 friend class G1EvacuateFollowersClosure;
227 friend class G1ParScanThreadState;
228 friend class G1ParScanClosureSuper;
229 friend class G1ParEvacuateFollowersClosure;
230 friend class G1ParTask;
231 friend class G1FreeGarbageRegionClosure;
232 friend class RefineCardTableEntryClosure;
233 friend class G1PrepareCompactClosure;
234 friend class RegionSorter;
235 friend class RegionResetter;
236 friend class CountRCClosure;
237 friend class EvacPopObjClosure;
238 friend class G1ParCleanupCTTask;
239
240 // Other related classes.
241 friend class G1MarkSweep;
242
243 private:
244 // The one and only G1CollectedHeap, so static functions can find it.
245 static G1CollectedHeap* _g1h;
246
247 static size_t _humongous_object_threshold_in_words;
248
249 // Storage for the G1 heap.
250 VirtualSpace _g1_storage;
251 MemRegion _g1_reserved;
252
253 // The part of _g1_storage that is currently committed.
254 MemRegion _g1_committed;
255
256 // The master free list. It will satisfy all new region allocations.
257 FreeRegionList _free_list;
258
259 // The secondary free list which contains regions that have been
260 // freed up during the cleanup process. This will be appended to the
261 // master free list when appropriate.
262 FreeRegionList _secondary_free_list;
263
264 // It keeps track of the old regions.
265 HeapRegionSet _old_set;
266
267 // It keeps track of the humongous regions.
268 HeapRegionSet _humongous_set;
269
270 // The number of regions we could create by expansion.
271 uint _expansion_regions;
272
273 // The block offset table for the G1 heap.
274 G1BlockOffsetSharedArray* _bot_shared;
275
276 // Tears down the region sets / lists so that they are empty and the
277 // regions on the heap do not belong to a region set / list. The
278 // only exception is the humongous set which we leave unaltered. If
279 // free_list_only is true, it will only tear down the master free
280 // list. It is called before a Full GC (free_list_only == false) or
281 // before heap shrinking (free_list_only == true).
282 void tear_down_region_sets(bool free_list_only);
283
284 // Rebuilds the region sets / lists so that they are repopulated to
285 // reflect the contents of the heap. The only exception is the
286 // humongous set which was not torn down in the first place. If
287 // free_list_only is true, it will only rebuild the master free
288 // list. It is called after a Full GC (free_list_only == false) or
289 // after heap shrinking (free_list_only == true).
290 void rebuild_region_sets(bool free_list_only);
291
292 // The sequence of all heap regions in the heap.
293 HeapRegionSeq _hrs;
294
295 // Alloc region used to satisfy mutator allocation requests.
296 MutatorAllocRegion _mutator_alloc_region;
297
298 // Alloc region used to satisfy allocation requests by the GC for
299 // survivor objects.
300 SurvivorGCAllocRegion _survivor_gc_alloc_region;
301
302 // PLAB sizing policy for survivors.
303 PLABStats _survivor_plab_stats;
304
305 // Alloc region used to satisfy allocation requests by the GC for
306 // old objects.
307 OldGCAllocRegion _old_gc_alloc_region;
308
309 // PLAB sizing policy for tenured objects.
310 PLABStats _old_plab_stats;
311
312 PLABStats* stats_for_purpose(GCAllocPurpose purpose) {
313 PLABStats* stats = NULL;
314
315 switch (purpose) {
316 case GCAllocForSurvived:
317 stats = &_survivor_plab_stats;
318 break;
319 case GCAllocForTenured:
320 stats = &_old_plab_stats;
321 break;
322 default:
323 assert(false, "unrecognized GCAllocPurpose");
324 }
325
326 return stats;
327 }
328
329 // The last old region we allocated to during the last GC.
330 // Typically, it is not full so we should re-use it during the next GC.
331 HeapRegion* _retained_old_gc_alloc_region;
332
333 // It specifies whether we should attempt to expand the heap after a
334 // region allocation failure. If heap expansion fails we set this to
335 // false so that we don't re-attempt the heap expansion (it's likely
336 // that subsequent expansion attempts will also fail if one fails).
337 // Currently, it is only consulted during GC and it's reset at the
338 // start of each GC.
339 bool _expand_heap_after_alloc_failure;
340
341 // It resets the mutator alloc region before new allocations can take place.
342 void init_mutator_alloc_region();
343
344 // It releases the mutator alloc region.
345 void release_mutator_alloc_region();
346
347 // It initializes the GC alloc regions at the start of a GC.
348 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
349
350 // Setup the retained old gc alloc region as the currrent old gc alloc region.
351 void use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info);
352
353 // It releases the GC alloc regions at the end of a GC.
354 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
355
356 // It does any cleanup that needs to be done on the GC alloc regions
357 // before a Full GC.
358 void abandon_gc_alloc_regions();
359
360 // Helper for monitoring and management support.
361 G1MonitoringSupport* _g1mm;
362
363 // Determines PLAB size for a particular allocation purpose.
364 size_t desired_plab_sz(GCAllocPurpose purpose);
365
366 // Outside of GC pauses, the number of bytes used in all regions other
367 // than the current allocation region.
368 size_t _summary_bytes_used;
369
370 // This array is used for a quick test on whether a reference points into
371 // the collection set or not. Each of the array's elements denotes whether the
372 // corresponding region is in the collection set or not.
373 G1FastCSetBiasedMappedArray _in_cset_fast_test;
374
375 volatile unsigned _gc_time_stamp;
376
377 size_t* _surviving_young_words;
378
379 G1HRPrinter _hr_printer;
380
381 void setup_surviving_young_words();
382 void update_surviving_young_words(size_t* surv_young_words);
383 void cleanup_surviving_young_words();
384
385 // It decides whether an explicit GC should start a concurrent cycle
386 // instead of doing a STW GC. Currently, a concurrent cycle is
387 // explicitly started if:
388 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
389 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
390 // (c) cause == _g1_humongous_allocation
391 bool should_do_concurrent_full_gc(GCCause::Cause cause);
392
393 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
394 // concurrent cycles) we have started.
395 volatile unsigned int _old_marking_cycles_started;
396
397 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
398 // concurrent cycles) we have completed.
399 volatile unsigned int _old_marking_cycles_completed;
400
401 bool _concurrent_cycle_started;
402
403 // This is a non-product method that is helpful for testing. It is
404 // called at the end of a GC and artificially expands the heap by
405 // allocating a number of dead regions. This way we can induce very
406 // frequent marking cycles and stress the cleanup / concurrent
407 // cleanup code more (as all the regions that will be allocated by
408 // this method will be found dead by the marking cycle).
409 void allocate_dummy_regions() PRODUCT_RETURN;
410
411 // Clear RSets after a compaction. It also resets the GC time stamps.
412 void clear_rsets_post_compaction();
413
414 // If the HR printer is active, dump the state of the regions in the
415 // heap after a compaction.
416 void print_hrs_post_compaction();
417
418 double verify(bool guard, const char* msg);
419 void verify_before_gc();
420 void verify_after_gc();
421
422 void log_gc_header();
423 void log_gc_footer(double pause_time_sec);
424
425 // These are macros so that, if the assert fires, we get the correct
426 // line number, file, etc.
427
428 #define heap_locking_asserts_err_msg(_extra_message_) \
429 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
430 (_extra_message_), \
431 BOOL_TO_STR(Heap_lock->owned_by_self()), \
432 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
433 BOOL_TO_STR(Thread::current()->is_VM_thread()))
434
435 #define assert_heap_locked() \
436 do { \
437 assert(Heap_lock->owned_by_self(), \
438 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
439 } while (0)
440
441 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
442 do { \
443 assert(Heap_lock->owned_by_self() || \
444 (SafepointSynchronize::is_at_safepoint() && \
445 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
446 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
447 "should be at a safepoint")); \
448 } while (0)
449
450 #define assert_heap_locked_and_not_at_safepoint() \
451 do { \
452 assert(Heap_lock->owned_by_self() && \
453 !SafepointSynchronize::is_at_safepoint(), \
454 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
455 "should not be at a safepoint")); \
456 } while (0)
457
458 #define assert_heap_not_locked() \
459 do { \
460 assert(!Heap_lock->owned_by_self(), \
461 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
462 } while (0)
463
464 #define assert_heap_not_locked_and_not_at_safepoint() \
465 do { \
466 assert(!Heap_lock->owned_by_self() && \
467 !SafepointSynchronize::is_at_safepoint(), \
468 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
469 "should not be at a safepoint")); \
470 } while (0)
471
472 #define assert_at_safepoint(_should_be_vm_thread_) \
473 do { \
474 assert(SafepointSynchronize::is_at_safepoint() && \
475 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
476 heap_locking_asserts_err_msg("should be at a safepoint")); \
477 } while (0)
478
479 #define assert_not_at_safepoint() \
480 do { \
481 assert(!SafepointSynchronize::is_at_safepoint(), \
482 heap_locking_asserts_err_msg("should not be at a safepoint")); \
483 } while (0)
484
485 protected:
486
487 // The young region list.
488 YoungList* _young_list;
489
490 // The current policy object for the collector.
491 G1CollectorPolicy* _g1_policy;
492
493 // This is the second level of trying to allocate a new region. If
494 // new_region() didn't find a region on the free_list, this call will
495 // check whether there's anything available on the
496 // secondary_free_list and/or wait for more regions to appear on
497 // that list, if _free_regions_coming is set.
498 HeapRegion* new_region_try_secondary_free_list(bool is_old);
499
500 // Try to allocate a single non-humongous HeapRegion sufficient for
501 // an allocation of the given word_size. If do_expand is true,
502 // attempt to expand the heap if necessary to satisfy the allocation
503 // request. If the region is to be used as an old region or for a
504 // humongous object, set is_old to true. If not, to false.
505 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
506
507 // Attempt to satisfy a humongous allocation request of the given
508 // size by finding a contiguous set of free regions of num_regions
509 // length and remove them from the master free list. Return the
510 // index of the first region or G1_NULL_HRS_INDEX if the search
511 // was unsuccessful.
512 uint humongous_obj_allocate_find_first(uint num_regions,
513 size_t word_size);
514
515 // Initialize a contiguous set of free regions of length num_regions
516 // and starting at index first so that they appear as a single
517 // humongous region.
518 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
519 uint num_regions,
520 size_t word_size);
521
522 // Attempt to allocate a humongous object of the given size. Return
523 // NULL if unsuccessful.
524 HeapWord* humongous_obj_allocate(size_t word_size);
525
526 // The following two methods, allocate_new_tlab() and
527 // mem_allocate(), are the two main entry points from the runtime
528 // into the G1's allocation routines. They have the following
529 // assumptions:
530 //
531 // * They should both be called outside safepoints.
532 //
533 // * They should both be called without holding the Heap_lock.
534 //
535 // * All allocation requests for new TLABs should go to
536 // allocate_new_tlab().
537 //
538 // * All non-TLAB allocation requests should go to mem_allocate().
539 //
540 // * If either call cannot satisfy the allocation request using the
541 // current allocating region, they will try to get a new one. If
542 // this fails, they will attempt to do an evacuation pause and
543 // retry the allocation.
544 //
545 // * If all allocation attempts fail, even after trying to schedule
546 // an evacuation pause, allocate_new_tlab() will return NULL,
547 // whereas mem_allocate() will attempt a heap expansion and/or
548 // schedule a Full GC.
549 //
550 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
551 // should never be called with word_size being humongous. All
552 // humongous allocation requests should go to mem_allocate() which
553 // will satisfy them with a special path.
554
555 virtual HeapWord* allocate_new_tlab(size_t word_size);
556
557 virtual HeapWord* mem_allocate(size_t word_size,
558 bool* gc_overhead_limit_was_exceeded);
559
560 // The following three methods take a gc_count_before_ret
561 // parameter which is used to return the GC count if the method
562 // returns NULL. Given that we are required to read the GC count
563 // while holding the Heap_lock, and these paths will take the
564 // Heap_lock at some point, it's easier to get them to read the GC
565 // count while holding the Heap_lock before they return NULL instead
566 // of the caller (namely: mem_allocate()) having to also take the
567 // Heap_lock just to read the GC count.
568
569 // First-level mutator allocation attempt: try to allocate out of
570 // the mutator alloc region without taking the Heap_lock. This
571 // should only be used for non-humongous allocations.
572 inline HeapWord* attempt_allocation(size_t word_size,
573 unsigned int* gc_count_before_ret,
574 int* gclocker_retry_count_ret);
575
576 // Second-level mutator allocation attempt: take the Heap_lock and
577 // retry the allocation attempt, potentially scheduling a GC
578 // pause. This should only be used for non-humongous allocations.
579 HeapWord* attempt_allocation_slow(size_t word_size,
580 unsigned int* gc_count_before_ret,
581 int* gclocker_retry_count_ret);
582
583 // Takes the Heap_lock and attempts a humongous allocation. It can
584 // potentially schedule a GC pause.
585 HeapWord* attempt_allocation_humongous(size_t word_size,
586 unsigned int* gc_count_before_ret,
587 int* gclocker_retry_count_ret);
588
589 // Allocation attempt that should be called during safepoints (e.g.,
590 // at the end of a successful GC). expect_null_mutator_alloc_region
591 // specifies whether the mutator alloc region is expected to be NULL
592 // or not.
593 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
594 bool expect_null_mutator_alloc_region);
595
596 // It dirties the cards that cover the block so that so that the post
597 // write barrier never queues anything when updating objects on this
598 // block. It is assumed (and in fact we assert) that the block
599 // belongs to a young region.
600 inline void dirty_young_block(HeapWord* start, size_t word_size);
601
602 // Allocate blocks during garbage collection. Will ensure an
603 // allocation region, either by picking one or expanding the
604 // heap, and then allocate a block of the given size. The block
605 // may not be a humongous - it must fit into a single heap region.
606 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
607
608 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
609 HeapRegion* alloc_region,
610 bool par,
611 size_t word_size);
612
613 // Ensure that no further allocations can happen in "r", bearing in mind
614 // that parallel threads might be attempting allocations.
615 void par_allocate_remaining_space(HeapRegion* r);
616
617 // Allocation attempt during GC for a survivor object / PLAB.
618 inline HeapWord* survivor_attempt_allocation(size_t word_size);
619
620 // Allocation attempt during GC for an old object / PLAB.
621 inline HeapWord* old_attempt_allocation(size_t word_size);
622
623 // These methods are the "callbacks" from the G1AllocRegion class.
624
625 // For mutator alloc regions.
626 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
627 void retire_mutator_alloc_region(HeapRegion* alloc_region,
628 size_t allocated_bytes);
629
630 // For GC alloc regions.
631 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
632 GCAllocPurpose ap);
633 void retire_gc_alloc_region(HeapRegion* alloc_region,
634 size_t allocated_bytes, GCAllocPurpose ap);
635
636 // - if explicit_gc is true, the GC is for a System.gc() or a heap
637 // inspection request and should collect the entire heap
638 // - if clear_all_soft_refs is true, all soft references should be
639 // cleared during the GC
640 // - if explicit_gc is false, word_size describes the allocation that
641 // the GC should attempt (at least) to satisfy
642 // - it returns false if it is unable to do the collection due to the
643 // GC locker being active, true otherwise
644 bool do_collection(bool explicit_gc,
645 bool clear_all_soft_refs,
646 size_t word_size);
647
648 // Callback from VM_G1CollectFull operation.
649 // Perform a full collection.
650 virtual void do_full_collection(bool clear_all_soft_refs);
651
652 // Resize the heap if necessary after a full collection. If this is
653 // after a collect-for allocation, "word_size" is the allocation size,
654 // and will be considered part of the used portion of the heap.
655 void resize_if_necessary_after_full_collection(size_t word_size);
656
657 // Callback from VM_G1CollectForAllocation operation.
658 // This function does everything necessary/possible to satisfy a
659 // failed allocation request (including collection, expansion, etc.)
660 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
661
662 // Attempting to expand the heap sufficiently
663 // to support an allocation of the given "word_size". If
664 // successful, perform the allocation and return the address of the
665 // allocated block, or else "NULL".
666 HeapWord* expand_and_allocate(size_t word_size);
667
668 // Process any reference objects discovered during
669 // an incremental evacuation pause.
670 void process_discovered_references(uint no_of_gc_workers);
671
672 // Enqueue any remaining discovered references
673 // after processing.
674 void enqueue_discovered_references(uint no_of_gc_workers);
675
676 public:
677
678 G1MonitoringSupport* g1mm() {
679 assert(_g1mm != NULL, "should have been initialized");
680 return _g1mm;
681 }
682
683 // Expand the garbage-first heap by at least the given size (in bytes!).
684 // Returns true if the heap was expanded by the requested amount;
685 // false otherwise.
686 // (Rounds up to a HeapRegion boundary.)
687 bool expand(size_t expand_bytes);
688
689 // Do anything common to GC's.
690 virtual void gc_prologue(bool full);
691 virtual void gc_epilogue(bool full);
692
693 // We register a region with the fast "in collection set" test. We
694 // simply set to true the array slot corresponding to this region.
695 void register_region_with_in_cset_fast_test(HeapRegion* r) {
696 _in_cset_fast_test.set_by_index(r->hrs_index(), true);
697 }
698
699 // This is a fast test on whether a reference points into the
700 // collection set or not. Assume that the reference
701 // points into the heap.
702 inline bool in_cset_fast_test(oop obj);
703
704 void clear_cset_fast_test() {
705 _in_cset_fast_test.clear();
706 }
707
708 // This is called at the start of either a concurrent cycle or a Full
709 // GC to update the number of old marking cycles started.
710 void increment_old_marking_cycles_started();
711
712 // This is called at the end of either a concurrent cycle or a Full
713 // GC to update the number of old marking cycles completed. Those two
714 // can happen in a nested fashion, i.e., we start a concurrent
715 // cycle, a Full GC happens half-way through it which ends first,
716 // and then the cycle notices that a Full GC happened and ends
717 // too. The concurrent parameter is a boolean to help us do a bit
718 // tighter consistency checking in the method. If concurrent is
719 // false, the caller is the inner caller in the nesting (i.e., the
720 // Full GC). If concurrent is true, the caller is the outer caller
721 // in this nesting (i.e., the concurrent cycle). Further nesting is
722 // not currently supported. The end of this call also notifies
723 // the FullGCCount_lock in case a Java thread is waiting for a full
724 // GC to happen (e.g., it called System.gc() with
725 // +ExplicitGCInvokesConcurrent).
726 void increment_old_marking_cycles_completed(bool concurrent);
727
728 unsigned int old_marking_cycles_completed() {
729 return _old_marking_cycles_completed;
730 }
731
732 void register_concurrent_cycle_start(const Ticks& start_time);
733 void register_concurrent_cycle_end();
734 void trace_heap_after_concurrent_cycle();
735
736 G1YCType yc_type();
737
738 G1HRPrinter* hr_printer() { return &_hr_printer; }
739
740 // Frees a non-humongous region by initializing its contents and
741 // adding it to the free list that's passed as a parameter (this is
742 // usually a local list which will be appended to the master free
743 // list later). The used bytes of freed regions are accumulated in
744 // pre_used. If par is true, the region's RSet will not be freed
745 // up. The assumption is that this will be done later.
746 // The locked parameter indicates if the caller has already taken
747 // care of proper synchronization. This may allow some optimizations.
748 void free_region(HeapRegion* hr,
749 FreeRegionList* free_list,
750 bool par,
751 bool locked = false);
752
753 // Frees a humongous region by collapsing it into individual regions
754 // and calling free_region() for each of them. The freed regions
755 // will be added to the free list that's passed as a parameter (this
756 // is usually a local list which will be appended to the master free
757 // list later). The used bytes of freed regions are accumulated in
758 // pre_used. If par is true, the region's RSet will not be freed
759 // up. The assumption is that this will be done later.
760 void free_humongous_region(HeapRegion* hr,
761 FreeRegionList* free_list,
762 bool par);
763 protected:
764
765 // Shrink the garbage-first heap by at most the given size (in bytes!).
766 // (Rounds down to a HeapRegion boundary.)
767 virtual void shrink(size_t expand_bytes);
768 void shrink_helper(size_t expand_bytes);
769
770 #if TASKQUEUE_STATS
771 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
772 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
773 void reset_taskqueue_stats();
774 #endif // TASKQUEUE_STATS
775
776 // Schedule the VM operation that will do an evacuation pause to
777 // satisfy an allocation request of word_size. *succeeded will
778 // return whether the VM operation was successful (it did do an
779 // evacuation pause) or not (another thread beat us to it or the GC
780 // locker was active). Given that we should not be holding the
781 // Heap_lock when we enter this method, we will pass the
782 // gc_count_before (i.e., total_collections()) as a parameter since
783 // it has to be read while holding the Heap_lock. Currently, both
784 // methods that call do_collection_pause() release the Heap_lock
785 // before the call, so it's easy to read gc_count_before just before.
786 HeapWord* do_collection_pause(size_t word_size,
787 unsigned int gc_count_before,
788 bool* succeeded,
789 GCCause::Cause gc_cause);
790
791 // The guts of the incremental collection pause, executed by the vm
792 // thread. It returns false if it is unable to do the collection due
793 // to the GC locker being active, true otherwise
794 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
795
796 // Actually do the work of evacuating the collection set.
797 void evacuate_collection_set(EvacuationInfo& evacuation_info);
798
799 // The g1 remembered set of the heap.
800 G1RemSet* _g1_rem_set;
801
802 // A set of cards that cover the objects for which the Rsets should be updated
803 // concurrently after the collection.
804 DirtyCardQueueSet _dirty_card_queue_set;
805
806 // The closure used to refine a single card.
807 RefineCardTableEntryClosure* _refine_cte_cl;
808
809 // A function to check the consistency of dirty card logs.
810 void check_ct_logs_at_safepoint();
811
812 // A DirtyCardQueueSet that is used to hold cards that contain
813 // references into the current collection set. This is used to
814 // update the remembered sets of the regions in the collection
815 // set in the event of an evacuation failure.
816 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
817
818 // After a collection pause, make the regions in the CS into free
819 // regions.
820 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
821
822 // Abandon the current collection set without recording policy
823 // statistics or updating free lists.
824 void abandon_collection_set(HeapRegion* cs_head);
825
826 // Applies "scan_non_heap_roots" to roots outside the heap,
827 // "scan_rs" to roots inside the heap (having done "set_region" to
828 // indicate the region in which the root resides),
829 // and does "scan_metadata" If "scan_rs" is
830 // NULL, then this step is skipped. The "worker_i"
831 // param is for use with parallel roots processing, and should be
832 // the "i" of the calling parallel worker thread's work(i) function.
833 // In the sequential case this param will be ignored.
834 void g1_process_roots(OopClosure* scan_non_heap_roots,
835 OopClosure* scan_non_heap_weak_roots,
836 OopsInHeapRegionClosure* scan_rs,
837 CLDClosure* scan_strong_clds,
838 CLDClosure* scan_weak_clds,
839 CodeBlobClosure* scan_strong_code,
840 uint worker_i);
841
842 // Notifies all the necessary spaces that the committed space has
843 // been updated (either expanded or shrunk). It should be called
844 // after _g1_storage is updated.
845 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
846
847 // The concurrent marker (and the thread it runs in.)
848 ConcurrentMark* _cm;
849 ConcurrentMarkThread* _cmThread;
850 bool _mark_in_progress;
851
852 // The concurrent refiner.
853 ConcurrentG1Refine* _cg1r;
854
855 // The parallel task queues
856 RefToScanQueueSet *_task_queues;
857
858 // True iff a evacuation has failed in the current collection.
859 bool _evacuation_failed;
860
861 EvacuationFailedInfo* _evacuation_failed_info_array;
862
863 // Failed evacuations cause some logical from-space objects to have
864 // forwarding pointers to themselves. Reset them.
865 void remove_self_forwarding_pointers();
866
867 // Together, these store an object with a preserved mark, and its mark value.
868 Stack<oop, mtGC> _objs_with_preserved_marks;
869 Stack<markOop, mtGC> _preserved_marks_of_objs;
870
871 // Preserve the mark of "obj", if necessary, in preparation for its mark
872 // word being overwritten with a self-forwarding-pointer.
873 void preserve_mark_if_necessary(oop obj, markOop m);
874
875 // The stack of evac-failure objects left to be scanned.
876 GrowableArray<oop>* _evac_failure_scan_stack;
877 // The closure to apply to evac-failure objects.
878
879 OopsInHeapRegionClosure* _evac_failure_closure;
880 // Set the field above.
881 void
882 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
883 _evac_failure_closure = evac_failure_closure;
884 }
885
886 // Push "obj" on the scan stack.
887 void push_on_evac_failure_scan_stack(oop obj);
888 // Process scan stack entries until the stack is empty.
889 void drain_evac_failure_scan_stack();
890 // True iff an invocation of "drain_scan_stack" is in progress; to
891 // prevent unnecessary recursion.
892 bool _drain_in_progress;
893
894 // Do any necessary initialization for evacuation-failure handling.
895 // "cl" is the closure that will be used to process evac-failure
896 // objects.
897 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
898 // Do any necessary cleanup for evacuation-failure handling data
899 // structures.
900 void finalize_for_evac_failure();
901
902 // An attempt to evacuate "obj" has failed; take necessary steps.
903 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
904 void handle_evacuation_failure_common(oop obj, markOop m);
905
906 #ifndef PRODUCT
907 // Support for forcing evacuation failures. Analogous to
908 // PromotionFailureALot for the other collectors.
909
910 // Records whether G1EvacuationFailureALot should be in effect
911 // for the current GC
912 bool _evacuation_failure_alot_for_current_gc;
913
914 // Used to record the GC number for interval checking when
915 // determining whether G1EvaucationFailureALot is in effect
916 // for the current GC.
917 size_t _evacuation_failure_alot_gc_number;
918
919 // Count of the number of evacuations between failures.
920 volatile size_t _evacuation_failure_alot_count;
921
922 // Set whether G1EvacuationFailureALot should be in effect
923 // for the current GC (based upon the type of GC and which
924 // command line flags are set);
925 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
926 bool during_initial_mark,
927 bool during_marking);
928
929 inline void set_evacuation_failure_alot_for_current_gc();
930
931 // Return true if it's time to cause an evacuation failure.
932 inline bool evacuation_should_fail();
933
934 // Reset the G1EvacuationFailureALot counters. Should be called at
935 // the end of an evacuation pause in which an evacuation failure occurred.
936 inline void reset_evacuation_should_fail();
937 #endif // !PRODUCT
938
939 // ("Weak") Reference processing support.
940 //
941 // G1 has 2 instances of the reference processor class. One
942 // (_ref_processor_cm) handles reference object discovery
943 // and subsequent processing during concurrent marking cycles.
944 //
945 // The other (_ref_processor_stw) handles reference object
946 // discovery and processing during full GCs and incremental
947 // evacuation pauses.
948 //
949 // During an incremental pause, reference discovery will be
950 // temporarily disabled for _ref_processor_cm and will be
951 // enabled for _ref_processor_stw. At the end of the evacuation
952 // pause references discovered by _ref_processor_stw will be
953 // processed and discovery will be disabled. The previous
954 // setting for reference object discovery for _ref_processor_cm
955 // will be re-instated.
956 //
957 // At the start of marking:
958 // * Discovery by the CM ref processor is verified to be inactive
959 // and it's discovered lists are empty.
960 // * Discovery by the CM ref processor is then enabled.
961 //
962 // At the end of marking:
963 // * Any references on the CM ref processor's discovered
964 // lists are processed (possibly MT).
965 //
966 // At the start of full GC we:
967 // * Disable discovery by the CM ref processor and
968 // empty CM ref processor's discovered lists
969 // (without processing any entries).
970 // * Verify that the STW ref processor is inactive and it's
971 // discovered lists are empty.
972 // * Temporarily set STW ref processor discovery as single threaded.
973 // * Temporarily clear the STW ref processor's _is_alive_non_header
974 // field.
975 // * Finally enable discovery by the STW ref processor.
976 //
977 // The STW ref processor is used to record any discovered
978 // references during the full GC.
979 //
980 // At the end of a full GC we:
981 // * Enqueue any reference objects discovered by the STW ref processor
982 // that have non-live referents. This has the side-effect of
983 // making the STW ref processor inactive by disabling discovery.
984 // * Verify that the CM ref processor is still inactive
985 // and no references have been placed on it's discovered
986 // lists (also checked as a precondition during initial marking).
987
988 // The (stw) reference processor...
989 ReferenceProcessor* _ref_processor_stw;
990
991 STWGCTimer* _gc_timer_stw;
992 ConcurrentGCTimer* _gc_timer_cm;
993
994 G1OldTracer* _gc_tracer_cm;
995 G1NewTracer* _gc_tracer_stw;
996
997 // During reference object discovery, the _is_alive_non_header
998 // closure (if non-null) is applied to the referent object to
999 // determine whether the referent is live. If so then the
1000 // reference object does not need to be 'discovered' and can
1001 // be treated as a regular oop. This has the benefit of reducing
1002 // the number of 'discovered' reference objects that need to
1003 // be processed.
1004 //
1005 // Instance of the is_alive closure for embedding into the
1006 // STW reference processor as the _is_alive_non_header field.
1007 // Supplying a value for the _is_alive_non_header field is
1008 // optional but doing so prevents unnecessary additions to
1009 // the discovered lists during reference discovery.
1010 G1STWIsAliveClosure _is_alive_closure_stw;
1011
1012 // The (concurrent marking) reference processor...
1013 ReferenceProcessor* _ref_processor_cm;
1014
1015 // Instance of the concurrent mark is_alive closure for embedding
1016 // into the Concurrent Marking reference processor as the
1017 // _is_alive_non_header field. Supplying a value for the
1018 // _is_alive_non_header field is optional but doing so prevents
1019 // unnecessary additions to the discovered lists during reference
1020 // discovery.
1021 G1CMIsAliveClosure _is_alive_closure_cm;
1022
1023 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
1024 HeapRegion** _worker_cset_start_region;
1025
1026 // Time stamp to validate the regions recorded in the cache
1027 // used by G1CollectedHeap::start_cset_region_for_worker().
1028 // The heap region entry for a given worker is valid iff
1029 // the associated time stamp value matches the current value
1030 // of G1CollectedHeap::_gc_time_stamp.
1031 unsigned int* _worker_cset_start_region_time_stamp;
1032
1033 enum G1H_process_roots_tasks {
1034 G1H_PS_filter_satb_buffers,
1035 G1H_PS_refProcessor_oops_do,
1036 // Leave this one last.
1037 G1H_PS_NumElements
1038 };
1039
1040 SubTasksDone* _process_strong_tasks;
1041
1042 volatile bool _free_regions_coming;
1043
1044 public:
1045
1046 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
1047
1048 void set_refine_cte_cl_concurrency(bool concurrent);
1049
1050 RefToScanQueue *task_queue(int i) const;
1051
1052 // A set of cards where updates happened during the GC
1053 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1054
1055 // A DirtyCardQueueSet that is used to hold cards that contain
1056 // references into the current collection set. This is used to
1057 // update the remembered sets of the regions in the collection
1058 // set in the event of an evacuation failure.
1059 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1060 { return _into_cset_dirty_card_queue_set; }
1061
1062 // Create a G1CollectedHeap with the specified policy.
1063 // Must call the initialize method afterwards.
1064 // May not return if something goes wrong.
1065 G1CollectedHeap(G1CollectorPolicy* policy);
1066
1067 // Initialize the G1CollectedHeap to have the initial and
1068 // maximum sizes and remembered and barrier sets
1069 // specified by the policy object.
1070 jint initialize();
1071
1072 virtual void stop();
1073
1074 // Return the (conservative) maximum heap alignment for any G1 heap
1075 static size_t conservative_max_heap_alignment();
1076
1077 // Initialize weak reference processing.
1078 virtual void ref_processing_init();
1079
1080 void set_par_threads(uint t) {
1081 SharedHeap::set_par_threads(t);
1082 // Done in SharedHeap but oddly there are
1083 // two _process_strong_tasks's in a G1CollectedHeap
1084 // so do it here too.
1085 _process_strong_tasks->set_n_threads(t);
1086 }
1087
1088 // Set _n_par_threads according to a policy TBD.
1089 void set_par_threads();
1090
1091 void set_n_termination(int t) {
1092 _process_strong_tasks->set_n_threads(t);
1093 }
1094
1095 virtual CollectedHeap::Name kind() const {
1096 return CollectedHeap::G1CollectedHeap;
1097 }
1098
1099 // The current policy object for the collector.
1100 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1101
1102 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1103
1104 // Adaptive size policy. No such thing for g1.
1105 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1106
1107 // The rem set and barrier set.
1108 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1109
1110 unsigned get_gc_time_stamp() {
1111 return _gc_time_stamp;
1112 }
1113
1114 inline void reset_gc_time_stamp();
1115
1116 void check_gc_time_stamps() PRODUCT_RETURN;
1117
1118 inline void increment_gc_time_stamp();
1119
1120 // Reset the given region's GC timestamp. If it's starts humongous,
1121 // also reset the GC timestamp of its corresponding
1122 // continues humongous regions too.
1123 void reset_gc_time_stamps(HeapRegion* hr);
1124
1125 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1126 DirtyCardQueue* into_cset_dcq,
1127 bool concurrent, uint worker_i);
1128
1129 // The shared block offset table array.
1130 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1131
1132 // Reference Processing accessors
1133
1134 // The STW reference processor....
1135 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1136
1137 // The Concurrent Marking reference processor...
1138 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1139
1140 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1141 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1142
1143 virtual size_t capacity() const;
1144 virtual size_t used() const;
1145 // This should be called when we're not holding the heap lock. The
1146 // result might be a bit inaccurate.
1147 size_t used_unlocked() const;
1148 size_t recalculate_used() const;
1149
1150 // These virtual functions do the actual allocation.
1151 // Some heaps may offer a contiguous region for shared non-blocking
1152 // allocation, via inlined code (by exporting the address of the top and
1153 // end fields defining the extent of the contiguous allocation region.)
1154 // But G1CollectedHeap doesn't yet support this.
1155
1156 virtual bool is_maximal_no_gc() const {
1157 return _g1_storage.uncommitted_size() == 0;
1158 }
1159
1160 // The total number of regions in the heap.
1161 uint n_regions() const { return _hrs.length(); }
1162
1163 // The max number of regions in the heap.
1164 uint max_regions() const { return _hrs.max_length(); }
1165
1166 // The number of regions that are completely free.
1167 uint free_regions() const { return _free_list.length(); }
1168
1169 // The number of regions that are not completely free.
1170 uint used_regions() const { return n_regions() - free_regions(); }
1171
1172 // The number of regions available for "regular" expansion.
1173 uint expansion_regions() const { return _expansion_regions; }
1174
1175 // Factory method for HeapRegion instances. It will return NULL if
1176 // the allocation fails.
1177 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
1178
1179 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1180 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1181 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1182 void verify_dirty_young_regions() PRODUCT_RETURN;
1183
1184 #ifndef PRODUCT
1185 // Make sure that the given bitmap has no marked objects in the
1186 // range [from,limit). If it does, print an error message and return
1187 // false. Otherwise, just return true. bitmap_name should be "prev"
1188 // or "next".
1189 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1190 HeapWord* from, HeapWord* limit);
1191
1192 // Verify that the prev / next bitmap range [tams,end) for the given
1193 // region has no marks. Return true if all is well, false if errors
1194 // are detected.
1195 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1196 #endif // PRODUCT
1197
1198 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1199 // the given region do not have any spurious marks. If errors are
1200 // detected, print appropriate error messages and crash.
1201 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1202
1203 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1204 // have any spurious marks. If errors are detected, print
1205 // appropriate error messages and crash.
1206 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1207
1208 // verify_region_sets() performs verification over the region
1209 // lists. It will be compiled in the product code to be used when
1210 // necessary (i.e., during heap verification).
1211 void verify_region_sets();
1212
1213 // verify_region_sets_optional() is planted in the code for
1214 // list verification in non-product builds (and it can be enabled in
1215 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1216 #if HEAP_REGION_SET_FORCE_VERIFY
1217 void verify_region_sets_optional() {
1218 verify_region_sets();
1219 }
1220 #else // HEAP_REGION_SET_FORCE_VERIFY
1221 void verify_region_sets_optional() { }
1222 #endif // HEAP_REGION_SET_FORCE_VERIFY
1223
1224 #ifdef ASSERT
1225 bool is_on_master_free_list(HeapRegion* hr) {
1226 return hr->containing_set() == &_free_list;
1227 }
1228 #endif // ASSERT
1229
1230 // Wrapper for the region list operations that can be called from
1231 // methods outside this class.
1232
1233 void secondary_free_list_add(FreeRegionList* list) {
1234 _secondary_free_list.add_ordered(list);
1235 }
1236
1237 void append_secondary_free_list() {
1238 _free_list.add_ordered(&_secondary_free_list);
1239 }
1240
1241 void append_secondary_free_list_if_not_empty_with_lock() {
1242 // If the secondary free list looks empty there's no reason to
1243 // take the lock and then try to append it.
1244 if (!_secondary_free_list.is_empty()) {
1245 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1246 append_secondary_free_list();
1247 }
1248 }
1249
1250 inline void old_set_remove(HeapRegion* hr);
1251
1252 size_t non_young_capacity_bytes() {
1253 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1254 }
1255
1256 void set_free_regions_coming();
1257 void reset_free_regions_coming();
1258 bool free_regions_coming() { return _free_regions_coming; }
1259 void wait_while_free_regions_coming();
1260
1261 // Determine whether the given region is one that we are using as an
1262 // old GC alloc region.
1263 bool is_old_gc_alloc_region(HeapRegion* hr) {
1264 return hr == _retained_old_gc_alloc_region;
1265 }
1266
1267 // Perform a collection of the heap; intended for use in implementing
1268 // "System.gc". This probably implies as full a collection as the
1269 // "CollectedHeap" supports.
1270 virtual void collect(GCCause::Cause cause);
1271
1272 // The same as above but assume that the caller holds the Heap_lock.
1273 void collect_locked(GCCause::Cause cause);
1274
1275 // True iff an evacuation has failed in the most-recent collection.
1276 bool evacuation_failed() { return _evacuation_failed; }
1277
1278 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1279 void prepend_to_freelist(FreeRegionList* list);
1280 void decrement_summary_bytes(size_t bytes);
1281
1282 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1283 virtual bool is_in(const void* p) const;
1284
1285 // Return "TRUE" iff the given object address is within the collection
1286 // set.
1287 inline bool obj_in_cs(oop obj);
1288
1289 // Return "TRUE" iff the given object address is in the reserved
1290 // region of g1.
1291 bool is_in_g1_reserved(const void* p) const {
1292 return _g1_reserved.contains(p);
1293 }
1294
1295 // Returns a MemRegion that corresponds to the space that has been
1296 // reserved for the heap
1297 MemRegion g1_reserved() {
1298 return _g1_reserved;
1299 }
1300
1301 // Returns a MemRegion that corresponds to the space that has been
1302 // committed in the heap
1303 MemRegion g1_committed() {
1304 return _g1_committed;
1305 }
1306
1307 virtual bool is_in_closed_subset(const void* p) const;
1308
1309 G1SATBCardTableModRefBS* g1_barrier_set() {
1310 return (G1SATBCardTableModRefBS*) barrier_set();
1311 }
1312
1313 // This resets the card table to all zeros. It is used after
1314 // a collection pause which used the card table to claim cards.
1315 void cleanUpCardTable();
1316
1317 // Iteration functions.
1318
1319 // Iterate over all the ref-containing fields of all objects, calling
1320 // "cl.do_oop" on each.
1321 virtual void oop_iterate(ExtendedOopClosure* cl);
1322
1323 // Same as above, restricted to a memory region.
1324 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
1325
1326 // Iterate over all objects, calling "cl.do_object" on each.
1327 virtual void object_iterate(ObjectClosure* cl);
1328
1329 virtual void safe_object_iterate(ObjectClosure* cl) {
1330 object_iterate(cl);
1331 }
1332
1333 // Iterate over all spaces in use in the heap, in ascending address order.
1334 virtual void space_iterate(SpaceClosure* cl);
1335
1336 // Iterate over heap regions, in address order, terminating the
1337 // iteration early if the "doHeapRegion" method returns "true".
1338 void heap_region_iterate(HeapRegionClosure* blk) const;
1339
1340 // Return the region with the given index. It assumes the index is valid.
1341 inline HeapRegion* region_at(uint index) const;
1342
1343 // Divide the heap region sequence into "chunks" of some size (the number
1344 // of regions divided by the number of parallel threads times some
1345 // overpartition factor, currently 4). Assumes that this will be called
1346 // in parallel by ParallelGCThreads worker threads with distinct worker
1347 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1348 // calls will use the same "claim_value", and that that claim value is
1349 // different from the claim_value of any heap region before the start of
1350 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1351 // attempting to claim the first region in each chunk, and, if
1352 // successful, applying the closure to each region in the chunk (and
1353 // setting the claim value of the second and subsequent regions of the
1354 // chunk.) For now requires that "doHeapRegion" always returns "false",
1355 // i.e., that a closure never attempt to abort a traversal.
1356 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1357 uint worker,
1358 uint no_of_par_workers,
1359 jint claim_value);
1360
1361 // It resets all the region claim values to the default.
1362 void reset_heap_region_claim_values();
1363
1364 // Resets the claim values of regions in the current
1365 // collection set to the default.
1366 void reset_cset_heap_region_claim_values();
1367
1368 #ifdef ASSERT
1369 bool check_heap_region_claim_values(jint claim_value);
1370
1371 // Same as the routine above but only checks regions in the
1372 // current collection set.
1373 bool check_cset_heap_region_claim_values(jint claim_value);
1374 #endif // ASSERT
1375
1376 // Clear the cached cset start regions and (more importantly)
1377 // the time stamps. Called when we reset the GC time stamp.
1378 void clear_cset_start_regions();
1379
1380 // Given the id of a worker, obtain or calculate a suitable
1381 // starting region for iterating over the current collection set.
1382 HeapRegion* start_cset_region_for_worker(uint worker_i);
1383
1384 // This is a convenience method that is used by the
1385 // HeapRegionIterator classes to calculate the starting region for
1386 // each worker so that they do not all start from the same region.
1387 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
1388
1389 // Iterate over the regions (if any) in the current collection set.
1390 void collection_set_iterate(HeapRegionClosure* blk);
1391
1392 // As above but starting from region r
1393 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1394
1395 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1396
1397 // A CollectedHeap will contain some number of spaces. This finds the
1398 // space containing a given address, or else returns NULL.
1399 virtual Space* space_containing(const void* addr) const;
1400
1401 // Returns the HeapRegion that contains addr. addr must not be NULL.
1402 template <class T>
1403 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1404
1405 // Returns the HeapRegion that contains addr. addr must not be NULL.
1406 // If addr is within a humongous continues region, it returns its humongous start region.
1407 template <class T>
1408 inline HeapRegion* heap_region_containing(const T addr) const;
1409
1410 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1411 // each address in the (reserved) heap is a member of exactly
1412 // one block. The defining characteristic of a block is that it is
1413 // possible to find its size, and thus to progress forward to the next
1414 // block. (Blocks may be of different sizes.) Thus, blocks may
1415 // represent Java objects, or they might be free blocks in a
1416 // free-list-based heap (or subheap), as long as the two kinds are
1417 // distinguishable and the size of each is determinable.
1418
1419 // Returns the address of the start of the "block" that contains the
1420 // address "addr". We say "blocks" instead of "object" since some heaps
1421 // may not pack objects densely; a chunk may either be an object or a
1422 // non-object.
1423 virtual HeapWord* block_start(const void* addr) const;
1424
1425 // Requires "addr" to be the start of a chunk, and returns its size.
1426 // "addr + size" is required to be the start of a new chunk, or the end
1427 // of the active area of the heap.
1428 virtual size_t block_size(const HeapWord* addr) const;
1429
1430 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1431 // the block is an object.
1432 virtual bool block_is_obj(const HeapWord* addr) const;
1433
1434 // Does this heap support heap inspection? (+PrintClassHistogram)
1435 virtual bool supports_heap_inspection() const { return true; }
1436
1437 // Section on thread-local allocation buffers (TLABs)
1438 // See CollectedHeap for semantics.
1439
1440 bool supports_tlab_allocation() const;
1441 size_t tlab_capacity(Thread* ignored) const;
1442 size_t tlab_used(Thread* ignored) const;
1443 size_t max_tlab_size() const;
1444 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1445
1446 // Can a compiler initialize a new object without store barriers?
1447 // This permission only extends from the creation of a new object
1448 // via a TLAB up to the first subsequent safepoint. If such permission
1449 // is granted for this heap type, the compiler promises to call
1450 // defer_store_barrier() below on any slow path allocation of
1451 // a new object for which such initializing store barriers will
1452 // have been elided. G1, like CMS, allows this, but should be
1453 // ready to provide a compensating write barrier as necessary
1454 // if that storage came out of a non-young region. The efficiency
1455 // of this implementation depends crucially on being able to
1456 // answer very efficiently in constant time whether a piece of
1457 // storage in the heap comes from a young region or not.
1458 // See ReduceInitialCardMarks.
1459 virtual bool can_elide_tlab_store_barriers() const {
1460 return true;
1461 }
1462
1463 virtual bool card_mark_must_follow_store() const {
1464 return true;
1465 }
1466
1467 inline bool is_in_young(const oop obj);
1468
1469 #ifdef ASSERT
1470 virtual bool is_in_partial_collection(const void* p);
1471 #endif
1472
1473 virtual bool is_scavengable(const void* addr);
1474
1475 // We don't need barriers for initializing stores to objects
1476 // in the young gen: for the SATB pre-barrier, there is no
1477 // pre-value that needs to be remembered; for the remembered-set
1478 // update logging post-barrier, we don't maintain remembered set
1479 // information for young gen objects.
1480 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1481
1482 // Returns "true" iff the given word_size is "very large".
1483 static bool isHumongous(size_t word_size) {
1484 // Note this has to be strictly greater-than as the TLABs
1485 // are capped at the humongous threshold and we want to
1486 // ensure that we don't try to allocate a TLAB as
1487 // humongous and that we don't allocate a humongous
1488 // object in a TLAB.
1489 return word_size > _humongous_object_threshold_in_words;
1490 }
1491
1492 // Update mod union table with the set of dirty cards.
1493 void updateModUnion();
1494
1495 // Set the mod union bits corresponding to the given memRegion. Note
1496 // that this is always a safe operation, since it doesn't clear any
1497 // bits.
1498 void markModUnionRange(MemRegion mr);
1499
1500 // Records the fact that a marking phase is no longer in progress.
1501 void set_marking_complete() {
1502 _mark_in_progress = false;
1503 }
1504 void set_marking_started() {
1505 _mark_in_progress = true;
1506 }
1507 bool mark_in_progress() {
1508 return _mark_in_progress;
1509 }
1510
1511 // Print the maximum heap capacity.
1512 virtual size_t max_capacity() const;
1513
1514 virtual jlong millis_since_last_gc();
1515
1516
1517 // Convenience function to be used in situations where the heap type can be
1518 // asserted to be this type.
1519 static G1CollectedHeap* heap();
1520
1521 void set_region_short_lived_locked(HeapRegion* hr);
1522 // add appropriate methods for any other surv rate groups
1523
1524 YoungList* young_list() const { return _young_list; }
1525
1526 // debugging
1527 bool check_young_list_well_formed() {
1528 return _young_list->check_list_well_formed();
1529 }
1530
1531 bool check_young_list_empty(bool check_heap,
1532 bool check_sample = true);
1533
1534 // *** Stuff related to concurrent marking. It's not clear to me that so
1535 // many of these need to be public.
1536
1537 // The functions below are helper functions that a subclass of
1538 // "CollectedHeap" can use in the implementation of its virtual
1539 // functions.
1540 // This performs a concurrent marking of the live objects in a
1541 // bitmap off to the side.
1542 void doConcurrentMark();
1543
1544 bool isMarkedPrev(oop obj) const;
1545 bool isMarkedNext(oop obj) const;
1546
1547 // Determine if an object is dead, given the object and also
1548 // the region to which the object belongs. An object is dead
1549 // iff a) it was not allocated since the last mark and b) it
1550 // is not marked.
1551 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1552 return
1553 !hr->obj_allocated_since_prev_marking(obj) &&
1554 !isMarkedPrev(obj);
1555 }
1556
1557 // This function returns true when an object has been
1558 // around since the previous marking and hasn't yet
1559 // been marked during this marking.
1560 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1561 return
1562 !hr->obj_allocated_since_next_marking(obj) &&
1563 !isMarkedNext(obj);
1564 }
1565
1566 // Determine if an object is dead, given only the object itself.
1567 // This will find the region to which the object belongs and
1568 // then call the region version of the same function.
1569
1570 // Added if it is NULL it isn't dead.
1571
1572 inline bool is_obj_dead(const oop obj) const;
1573
1574 inline bool is_obj_ill(const oop obj) const;
1575
1576 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1577 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1578 bool is_marked(oop obj, VerifyOption vo);
1579 const char* top_at_mark_start_str(VerifyOption vo);
1580
1581 ConcurrentMark* concurrent_mark() const { return _cm; }
1582
1583 // Refinement
1584
1585 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1586
1587 // The dirty cards region list is used to record a subset of regions
1588 // whose cards need clearing. The list if populated during the
1589 // remembered set scanning and drained during the card table
1590 // cleanup. Although the methods are reentrant, population/draining
1591 // phases must not overlap. For synchronization purposes the last
1592 // element on the list points to itself.
1593 HeapRegion* _dirty_cards_region_list;
1594 void push_dirty_cards_region(HeapRegion* hr);
1595 HeapRegion* pop_dirty_cards_region();
1596
1597 // Optimized nmethod scanning support routines
1598
1599 // Register the given nmethod with the G1 heap.
1600 virtual void register_nmethod(nmethod* nm);
1601
1602 // Unregister the given nmethod from the G1 heap.
1603 virtual void unregister_nmethod(nmethod* nm);
1604
1605 // Migrate the nmethods in the code root lists of the regions
1606 // in the collection set to regions in to-space. In the event
1607 // of an evacuation failure, nmethods that reference objects
1608 // that were not successfully evacuated are not migrated.
1609 void migrate_strong_code_roots();
1610
1611 // Free up superfluous code root memory.
1612 void purge_code_root_memory();
1613
1614 // Rebuild the strong code root lists for each region
1615 // after a full GC.
1616 void rebuild_strong_code_roots();
1617
1618 // Delete entries for dead interned string and clean up unreferenced symbols
1619 // in symbol table, possibly in parallel.
1620 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1621
1622 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1623 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1624
1625 // Redirty logged cards in the refinement queue.
1626 void redirty_logged_cards();
1627 // Verification
1628
1629 // The following is just to alert the verification code
1630 // that a full collection has occurred and that the
1631 // remembered sets are no longer up to date.
1632 bool _full_collection;
1633 void set_full_collection() { _full_collection = true;}
1634 void clear_full_collection() {_full_collection = false;}
1635 bool full_collection() {return _full_collection;}
1636
1637 // Perform any cleanup actions necessary before allowing a verification.
1638 virtual void prepare_for_verify();
1639
1640 // Perform verification.
1641
1642 // vo == UsePrevMarking -> use "prev" marking information,
1643 // vo == UseNextMarking -> use "next" marking information
1644 // vo == UseMarkWord -> use the mark word in the object header
1645 //
1646 // NOTE: Only the "prev" marking information is guaranteed to be
1647 // consistent most of the time, so most calls to this should use
1648 // vo == UsePrevMarking.
1649 // Currently, there is only one case where this is called with
1650 // vo == UseNextMarking, which is to verify the "next" marking
1651 // information at the end of remark.
1652 // Currently there is only one place where this is called with
1653 // vo == UseMarkWord, which is to verify the marking during a
1654 // full GC.
1655 void verify(bool silent, VerifyOption vo);
1656
1657 // Override; it uses the "prev" marking information
1658 virtual void verify(bool silent);
1659
1660 // The methods below are here for convenience and dispatch the
1661 // appropriate method depending on value of the given VerifyOption
1662 // parameter. The values for that parameter, and their meanings,
1663 // are the same as those above.
1664
1665 bool is_obj_dead_cond(const oop obj,
1666 const HeapRegion* hr,
1667 const VerifyOption vo) const;
1668
1669 bool is_obj_dead_cond(const oop obj,
1670 const VerifyOption vo) const;
1671
1672 // Printing
1673
1674 virtual void print_on(outputStream* st) const;
1675 virtual void print_extended_on(outputStream* st) const;
1676 virtual void print_on_error(outputStream* st) const;
1677
1678 virtual void print_gc_threads_on(outputStream* st) const;
1679 virtual void gc_threads_do(ThreadClosure* tc) const;
1680
1681 // Override
1682 void print_tracing_info() const;
1683
1684 // The following two methods are helpful for debugging RSet issues.
1685 void print_cset_rsets() PRODUCT_RETURN;
1686 void print_all_rsets() PRODUCT_RETURN;
1687
1688 public:
1689 size_t pending_card_num();
1690 size_t cards_scanned();
1691
1692 protected:
1693 size_t _max_heap_capacity;
1694 };
1695
1696 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1697 private:
1698 bool _retired;
1699
1700 public:
1701 G1ParGCAllocBuffer(size_t gclab_word_size);
1702 virtual ~G1ParGCAllocBuffer() {
1703 guarantee(_retired, "Allocation buffer has not been retired");
1704 }
1705
1706 virtual void set_buf(HeapWord* buf) {
1707 ParGCAllocBuffer::set_buf(buf);
1708 _retired = false;
1709 }
1710
1711 virtual void retire(bool end_of_gc, bool retain) {
1712 if (_retired) {
1713 return;
1714 }
1715 ParGCAllocBuffer::retire(end_of_gc, retain);
1716 _retired = true;
1717 }
1718 };
1719
1720 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP