1 /*
2 * Copyright (c) 2001, 2015, 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/g1AllocationContext.hpp"
29 #include "gc_implementation/g1/g1Allocator.hpp"
30 #include "gc_implementation/g1/concurrentMark.hpp"
31 #include "gc_implementation/g1/evacuationInfo.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.hpp"
33 #include "gc_implementation/g1/g1BiasedArray.hpp"
34 #include "gc_implementation/g1/g1HRPrinter.hpp"
35 #include "gc_implementation/g1/g1InCSetState.hpp"
36 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
37 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
38 #include "gc_implementation/g1/g1YCTypes.hpp"
39 #include "gc_implementation/g1/heapRegionManager.hpp"
40 #include "gc_implementation/g1/heapRegionSet.hpp"
41 #include "gc_implementation/shared/hSpaceCounters.hpp"
42 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
43 #include "memory/barrierSet.hpp"
44 #include "memory/memRegion.hpp"
45 #include "memory/sharedHeap.hpp"
46 #include "utilities/stack.hpp"
47
48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
49 // It uses the "Garbage First" heap organization and algorithm, which
50 // may combine concurrent marking with parallel, incremental compaction of
51 // heap subsets that will yield large amounts of garbage.
52
53 // Forward declarations
54 class HeapRegion;
55 class HRRSCleanupTask;
56 class GenerationSpec;
57 class OopsInHeapRegionClosure;
58 class G1KlassScanClosure;
59 class G1ScanHeapEvacClosure;
60 class ObjectClosure;
61 class SpaceClosure;
62 class CompactibleSpaceClosure;
63 class Space;
64 class G1CollectorPolicy;
65 class GenRemSet;
66 class G1RemSet;
67 class HeapRegionRemSetIterator;
68 class ConcurrentMark;
69 class ConcurrentMarkThread;
70 class ConcurrentG1Refine;
71 class ConcurrentGCTimer;
72 class GenerationCounters;
73 class STWGCTimer;
74 class G1NewTracer;
75 class G1OldTracer;
76 class EvacuationFailedInfo;
77 class nmethod;
78 class Ticks;
79
80 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
81 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
82
83 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
84 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
85
86 class YoungList : public CHeapObj<mtGC> {
87 private:
88 G1CollectedHeap* _g1h;
89
90 HeapRegion* _head;
91
92 HeapRegion* _survivor_head;
93 HeapRegion* _survivor_tail;
94
95 HeapRegion* _curr;
96
97 uint _length;
98 uint _survivor_length;
99
100 size_t _last_sampled_rs_lengths;
101 size_t _sampled_rs_lengths;
102
103 void empty_list(HeapRegion* list);
104
105 public:
106 YoungList(G1CollectedHeap* g1h);
107
108 void push_region(HeapRegion* hr);
109 void add_survivor_region(HeapRegion* hr);
110
111 void empty_list();
112 bool is_empty() { return _length == 0; }
113 uint length() { return _length; }
114 uint survivor_length() { return _survivor_length; }
115
116 // Currently we do not keep track of the used byte sum for the
117 // young list and the survivors and it'd be quite a lot of work to
118 // do so. When we'll eventually replace the young list with
119 // instances of HeapRegionLinkedList we'll get that for free. So,
120 // we'll report the more accurate information then.
121 size_t eden_used_bytes() {
122 assert(length() >= survivor_length(), "invariant");
123 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
124 }
125 size_t survivor_used_bytes() {
126 return (size_t) survivor_length() * HeapRegion::GrainBytes;
127 }
128
129 void rs_length_sampling_init();
130 bool rs_length_sampling_more();
131 void rs_length_sampling_next();
132
133 void reset_sampled_info() {
134 _last_sampled_rs_lengths = 0;
135 }
136 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
137
138 // for development purposes
139 void reset_auxilary_lists();
140 void clear() { _head = NULL; _length = 0; }
141
142 void clear_survivors() {
143 _survivor_head = NULL;
144 _survivor_tail = NULL;
145 _survivor_length = 0;
146 }
147
148 HeapRegion* first_region() { return _head; }
149 HeapRegion* first_survivor_region() { return _survivor_head; }
150 HeapRegion* last_survivor_region() { return _survivor_tail; }
151
152 // debugging
153 bool check_list_well_formed();
154 bool check_list_empty(bool check_sample = true);
155 void print();
156 };
157
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // reference processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 bool do_object_b(oop p);
168 };
169
170 class RefineCardTableEntryClosure;
171
172 class G1RegionMappingChangedListener : public G1MappingChangedListener {
173 private:
174 void reset_from_card_cache(uint start_idx, size_t num_regions);
175 public:
176 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
177 };
178
179 class G1CollectedHeap : public SharedHeap {
180 friend class VM_CollectForMetadataAllocation;
181 friend class VM_G1CollectForAllocation;
182 friend class VM_G1CollectFull;
183 friend class VM_G1IncCollectionPause;
184 friend class VMStructs;
185 friend class MutatorAllocRegion;
186 friend class SurvivorGCAllocRegion;
187 friend class OldGCAllocRegion;
188 friend class G1Allocator;
189 friend class G1DefaultAllocator;
190 friend class G1ResManAllocator;
191
192 // Closures used in implementation.
193 template <G1Barrier barrier, G1Mark do_mark_object>
194 friend class G1ParCopyClosure;
195 friend class G1IsAliveClosure;
196 friend class G1EvacuateFollowersClosure;
197 friend class G1ParScanThreadState;
198 friend class G1ParScanClosureSuper;
199 friend class G1ParEvacuateFollowersClosure;
200 friend class G1ParTask;
201 friend class G1ParGCAllocator;
202 friend class G1DefaultParGCAllocator;
203 friend class G1FreeGarbageRegionClosure;
204 friend class RefineCardTableEntryClosure;
205 friend class G1PrepareCompactClosure;
206 friend class RegionSorter;
207 friend class RegionResetter;
208 friend class CountRCClosure;
209 friend class EvacPopObjClosure;
210 friend class G1ParCleanupCTTask;
211
212 friend class G1FreeHumongousRegionClosure;
213 // Other related classes.
214 friend class G1MarkSweep;
215
216 // Testing classes.
217 friend class G1CheckCSetFastTableClosure;
218
219 private:
220 // The one and only G1CollectedHeap, so static functions can find it.
221 static G1CollectedHeap* _g1h;
222
223 static size_t _humongous_object_threshold_in_words;
224
225 // The secondary free list which contains regions that have been
226 // freed up during the cleanup process. This will be appended to
227 // the master free list when appropriate.
228 FreeRegionList _secondary_free_list;
229
230 // It keeps track of the old regions.
231 HeapRegionSet _old_set;
232
233 // It keeps track of the humongous regions.
234 HeapRegionSet _humongous_set;
235
236 void eagerly_reclaim_humongous_regions();
237
238 // The number of regions we could create by expansion.
239 uint _expansion_regions;
240
241 // The block offset table for the G1 heap.
242 G1BlockOffsetSharedArray* _bot_shared;
243
244 // Tears down the region sets / lists so that they are empty and the
245 // regions on the heap do not belong to a region set / list. The
246 // only exception is the humongous set which we leave unaltered. If
247 // free_list_only is true, it will only tear down the master free
248 // list. It is called before a Full GC (free_list_only == false) or
249 // before heap shrinking (free_list_only == true).
250 void tear_down_region_sets(bool free_list_only);
251
252 // Rebuilds the region sets / lists so that they are repopulated to
253 // reflect the contents of the heap. The only exception is the
254 // humongous set which was not torn down in the first place. If
255 // free_list_only is true, it will only rebuild the master free
256 // list. It is called after a Full GC (free_list_only == false) or
257 // after heap shrinking (free_list_only == true).
258 void rebuild_region_sets(bool free_list_only);
259
260 // Callback for region mapping changed events.
261 G1RegionMappingChangedListener _listener;
262
263 // The sequence of all heap regions in the heap.
264 HeapRegionManager _hrm;
265
266 // Class that handles the different kinds of allocations.
267 G1Allocator* _allocator;
268
269 // Statistics for each allocation context
270 AllocationContextStats _allocation_context_stats;
271
272 // PLAB sizing policy for survivors.
273 PLABStats _survivor_plab_stats;
274
275 // PLAB sizing policy for tenured objects.
276 PLABStats _old_plab_stats;
277
278 // It specifies whether we should attempt to expand the heap after a
279 // region allocation failure. If heap expansion fails we set this to
280 // false so that we don't re-attempt the heap expansion (it's likely
281 // that subsequent expansion attempts will also fail if one fails).
282 // Currently, it is only consulted during GC and it's reset at the
283 // start of each GC.
284 bool _expand_heap_after_alloc_failure;
285
286 // It resets the mutator alloc region before new allocations can take place.
287 void init_mutator_alloc_region();
288
289 // It releases the mutator alloc region.
290 void release_mutator_alloc_region();
291
292 // It initializes the GC alloc regions at the start of a GC.
293 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
294
295 // It releases the GC alloc regions at the end of a GC.
296 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
297
298 // It does any cleanup that needs to be done on the GC alloc regions
299 // before a Full GC.
300 void abandon_gc_alloc_regions();
301
302 // Helper for monitoring and management support.
303 G1MonitoringSupport* _g1mm;
304
305 // Records whether the region at the given index is (still) a
306 // candidate for eager reclaim. Only valid for humongous start
307 // regions; other regions have unspecified values. Humongous start
308 // regions are initialized at start of collection pause, with
309 // candidates removed from the set as they are found reachable from
310 // roots or the young generation.
311 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
312 protected:
313 bool default_value() const { return false; }
314 public:
315 void clear() { G1BiasedMappedArray<bool>::clear(); }
316 void set_candidate(uint region, bool value) {
317 set_by_index(region, value);
318 }
319 bool is_candidate(uint region) {
320 return get_by_index(region);
321 }
322 };
323
324 HumongousReclaimCandidates _humongous_reclaim_candidates;
325 // Stores whether during humongous object registration we found candidate regions.
326 // If not, we can skip a few steps.
327 bool _has_humongous_reclaim_candidates;
328
329 volatile unsigned _gc_time_stamp;
330
331 size_t* _surviving_young_words;
332
333 G1HRPrinter _hr_printer;
334
335 void setup_surviving_young_words();
336 void update_surviving_young_words(size_t* surv_young_words);
337 void cleanup_surviving_young_words();
338
339 // It decides whether an explicit GC should start a concurrent cycle
340 // instead of doing a STW GC. Currently, a concurrent cycle is
341 // explicitly started if:
342 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
343 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
344 // (c) cause == _g1_humongous_allocation
345 bool should_do_concurrent_full_gc(GCCause::Cause cause);
346
347 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
348 // concurrent cycles) we have started.
349 volatile uint _old_marking_cycles_started;
350
351 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
352 // concurrent cycles) we have completed.
353 volatile uint _old_marking_cycles_completed;
354
355 bool _concurrent_cycle_started;
356 bool _heap_summary_sent;
357
358 // This is a non-product method that is helpful for testing. It is
359 // called at the end of a GC and artificially expands the heap by
360 // allocating a number of dead regions. This way we can induce very
361 // frequent marking cycles and stress the cleanup / concurrent
362 // cleanup code more (as all the regions that will be allocated by
363 // this method will be found dead by the marking cycle).
364 void allocate_dummy_regions() PRODUCT_RETURN;
365
366 // Clear RSets after a compaction. It also resets the GC time stamps.
367 void clear_rsets_post_compaction();
368
369 // If the HR printer is active, dump the state of the regions in the
370 // heap after a compaction.
371 void print_hrm_post_compaction();
372
373 // Create a memory mapper for auxiliary data structures of the given size and
374 // translation factor.
375 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
376 size_t size,
377 size_t translation_factor);
378
379 double verify(bool guard, const char* msg);
380 void verify_before_gc();
381 void verify_after_gc();
382
383 void log_gc_header();
384 void log_gc_footer(double pause_time_sec);
385
386 // These are macros so that, if the assert fires, we get the correct
387 // line number, file, etc.
388
389 #define heap_locking_asserts_err_msg(_extra_message_) \
390 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
391 (_extra_message_), \
392 BOOL_TO_STR(Heap_lock->owned_by_self()), \
393 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
394 BOOL_TO_STR(Thread::current()->is_VM_thread()))
395
396 #define assert_heap_locked() \
397 do { \
398 assert(Heap_lock->owned_by_self(), \
399 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
400 } while (0)
401
402 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
403 do { \
404 assert(Heap_lock->owned_by_self() || \
405 (SafepointSynchronize::is_at_safepoint() && \
406 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
407 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
408 "should be at a safepoint")); \
409 } while (0)
410
411 #define assert_heap_locked_and_not_at_safepoint() \
412 do { \
413 assert(Heap_lock->owned_by_self() && \
414 !SafepointSynchronize::is_at_safepoint(), \
415 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
416 "should not be at a safepoint")); \
417 } while (0)
418
419 #define assert_heap_not_locked() \
420 do { \
421 assert(!Heap_lock->owned_by_self(), \
422 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
423 } while (0)
424
425 #define assert_heap_not_locked_and_not_at_safepoint() \
426 do { \
427 assert(!Heap_lock->owned_by_self() && \
428 !SafepointSynchronize::is_at_safepoint(), \
429 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
430 "should not be at a safepoint")); \
431 } while (0)
432
433 #define assert_at_safepoint(_should_be_vm_thread_) \
434 do { \
435 assert(SafepointSynchronize::is_at_safepoint() && \
436 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
437 heap_locking_asserts_err_msg("should be at a safepoint")); \
438 } while (0)
439
440 #define assert_not_at_safepoint() \
441 do { \
442 assert(!SafepointSynchronize::is_at_safepoint(), \
443 heap_locking_asserts_err_msg("should not be at a safepoint")); \
444 } while (0)
445
446 protected:
447
448 // The young region list.
449 YoungList* _young_list;
450
451 // The current policy object for the collector.
452 G1CollectorPolicy* _g1_policy;
453
454 // This is the second level of trying to allocate a new region. If
455 // new_region() didn't find a region on the free_list, this call will
456 // check whether there's anything available on the
457 // secondary_free_list and/or wait for more regions to appear on
458 // that list, if _free_regions_coming is set.
459 HeapRegion* new_region_try_secondary_free_list(bool is_old);
460
461 // Try to allocate a single non-humongous HeapRegion sufficient for
462 // an allocation of the given word_size. If do_expand is true,
463 // attempt to expand the heap if necessary to satisfy the allocation
464 // request. If the region is to be used as an old region or for a
465 // humongous object, set is_old to true. If not, to false.
466 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
467
468 // Initialize a contiguous set of free regions of length num_regions
469 // and starting at index first so that they appear as a single
470 // humongous region.
471 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
472 uint num_regions,
473 size_t word_size,
474 AllocationContext_t context);
475
476 // Attempt to allocate a humongous object of the given size. Return
477 // NULL if unsuccessful.
478 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
479
480 // The following two methods, allocate_new_tlab() and
481 // mem_allocate(), are the two main entry points from the runtime
482 // into the G1's allocation routines. They have the following
483 // assumptions:
484 //
485 // * They should both be called outside safepoints.
486 //
487 // * They should both be called without holding the Heap_lock.
488 //
489 // * All allocation requests for new TLABs should go to
490 // allocate_new_tlab().
491 //
492 // * All non-TLAB allocation requests should go to mem_allocate().
493 //
494 // * If either call cannot satisfy the allocation request using the
495 // current allocating region, they will try to get a new one. If
496 // this fails, they will attempt to do an evacuation pause and
497 // retry the allocation.
498 //
499 // * If all allocation attempts fail, even after trying to schedule
500 // an evacuation pause, allocate_new_tlab() will return NULL,
501 // whereas mem_allocate() will attempt a heap expansion and/or
502 // schedule a Full GC.
503 //
504 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
505 // should never be called with word_size being humongous. All
506 // humongous allocation requests should go to mem_allocate() which
507 // will satisfy them with a special path.
508
509 virtual HeapWord* allocate_new_tlab(size_t word_size);
510
511 virtual HeapWord* mem_allocate(size_t word_size,
512 bool* gc_overhead_limit_was_exceeded);
513
514 // The following three methods take a gc_count_before_ret
515 // parameter which is used to return the GC count if the method
516 // returns NULL. Given that we are required to read the GC count
517 // while holding the Heap_lock, and these paths will take the
518 // Heap_lock at some point, it's easier to get them to read the GC
519 // count while holding the Heap_lock before they return NULL instead
520 // of the caller (namely: mem_allocate()) having to also take the
521 // Heap_lock just to read the GC count.
522
523 // First-level mutator allocation attempt: try to allocate out of
524 // the mutator alloc region without taking the Heap_lock. This
525 // should only be used for non-humongous allocations.
526 inline HeapWord* attempt_allocation(size_t word_size,
527 uint* gc_count_before_ret,
528 uint* gclocker_retry_count_ret);
529
530 // Second-level mutator allocation attempt: take the Heap_lock and
531 // retry the allocation attempt, potentially scheduling a GC
532 // pause. This should only be used for non-humongous allocations.
533 HeapWord* attempt_allocation_slow(size_t word_size,
534 AllocationContext_t context,
535 uint* gc_count_before_ret,
536 uint* gclocker_retry_count_ret);
537
538 // Takes the Heap_lock and attempts a humongous allocation. It can
539 // potentially schedule a GC pause.
540 HeapWord* attempt_allocation_humongous(size_t word_size,
541 uint* gc_count_before_ret,
542 uint* gclocker_retry_count_ret);
543
544 // Allocation attempt that should be called during safepoints (e.g.,
545 // at the end of a successful GC). expect_null_mutator_alloc_region
546 // specifies whether the mutator alloc region is expected to be NULL
547 // or not.
548 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
549 AllocationContext_t context,
550 bool expect_null_mutator_alloc_region);
551
552 // It dirties the cards that cover the block so that so that the post
553 // write barrier never queues anything when updating objects on this
554 // block. It is assumed (and in fact we assert) that the block
555 // belongs to a young region.
556 inline void dirty_young_block(HeapWord* start, size_t word_size);
557
558 // Allocate blocks during garbage collection. Will ensure an
559 // allocation region, either by picking one or expanding the
560 // heap, and then allocate a block of the given size. The block
561 // may not be a humongous - it must fit into a single heap region.
562 inline HeapWord* par_allocate_during_gc(InCSetState dest,
563 size_t word_size,
564 AllocationContext_t context);
565 // Ensure that no further allocations can happen in "r", bearing in mind
566 // that parallel threads might be attempting allocations.
567 void par_allocate_remaining_space(HeapRegion* r);
568
569 // Allocation attempt during GC for a survivor object / PLAB.
570 inline HeapWord* survivor_attempt_allocation(size_t word_size,
571 AllocationContext_t context);
572
573 // Allocation attempt during GC for an old object / PLAB.
574 inline HeapWord* old_attempt_allocation(size_t word_size,
575 AllocationContext_t context);
576
577 // These methods are the "callbacks" from the G1AllocRegion class.
578
579 // For mutator alloc regions.
580 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
581 void retire_mutator_alloc_region(HeapRegion* alloc_region,
582 size_t allocated_bytes);
583
584 // For GC alloc regions.
585 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
586 InCSetState dest);
587 void retire_gc_alloc_region(HeapRegion* alloc_region,
588 size_t allocated_bytes, InCSetState dest);
589
590 // - if explicit_gc is true, the GC is for a System.gc() or a heap
591 // inspection request and should collect the entire heap
592 // - if clear_all_soft_refs is true, all soft references should be
593 // cleared during the GC
594 // - if explicit_gc is false, word_size describes the allocation that
595 // the GC should attempt (at least) to satisfy
596 // - it returns false if it is unable to do the collection due to the
597 // GC locker being active, true otherwise
598 bool do_collection(bool explicit_gc,
599 bool clear_all_soft_refs,
600 size_t word_size);
601
602 // Callback from VM_G1CollectFull operation.
603 // Perform a full collection.
604 virtual void do_full_collection(bool clear_all_soft_refs);
605
606 // Resize the heap if necessary after a full collection. If this is
607 // after a collect-for allocation, "word_size" is the allocation size,
608 // and will be considered part of the used portion of the heap.
609 void resize_if_necessary_after_full_collection(size_t word_size);
610
611 // Callback from VM_G1CollectForAllocation operation.
612 // This function does everything necessary/possible to satisfy a
613 // failed allocation request (including collection, expansion, etc.)
614 HeapWord* satisfy_failed_allocation(size_t word_size,
615 AllocationContext_t context,
616 bool* succeeded);
617
618 // Attempting to expand the heap sufficiently
619 // to support an allocation of the given "word_size". If
620 // successful, perform the allocation and return the address of the
621 // allocated block, or else "NULL".
622 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
623
624 // Process any reference objects discovered during
625 // an incremental evacuation pause.
626 void process_discovered_references(uint no_of_gc_workers);
627
628 // Enqueue any remaining discovered references
629 // after processing.
630 void enqueue_discovered_references(uint no_of_gc_workers);
631
632 public:
633
634 G1Allocator* allocator() {
635 return _allocator;
636 }
637
638 G1MonitoringSupport* g1mm() {
639 assert(_g1mm != NULL, "should have been initialized");
640 return _g1mm;
641 }
642
643 // Expand the garbage-first heap by at least the given size (in bytes!).
644 // Returns true if the heap was expanded by the requested amount;
645 // false otherwise.
646 // (Rounds up to a HeapRegion boundary.)
647 bool expand(size_t expand_bytes);
648
649 // Returns the PLAB statistics for a given destination.
650 inline PLABStats* alloc_buffer_stats(InCSetState dest);
651
652 // Determines PLAB size for a given destination.
653 inline size_t desired_plab_sz(InCSetState dest);
654
655 inline AllocationContextStats& allocation_context_stats();
656
657 // Do anything common to GC's.
658 virtual void gc_prologue(bool full);
659 virtual void gc_epilogue(bool full);
660
661 // Modify the reclaim candidate set and test for presence.
662 // These are only valid for starts_humongous regions.
663 inline void set_humongous_reclaim_candidate(uint region, bool value);
664 inline bool is_humongous_reclaim_candidate(uint region);
665
666 // Remove from the reclaim candidate set. Also remove from the
667 // collection set so that later encounters avoid the slow path.
668 inline void set_humongous_is_live(oop obj);
669
670 // Register the given region to be part of the collection set.
671 inline void register_humongous_region_with_in_cset_fast_test(uint index);
672 // Register regions with humongous objects (actually on the start region) in
673 // the in_cset_fast_test table.
674 void register_humongous_regions_with_in_cset_fast_test();
675 // We register a region with the fast "in collection set" test. We
676 // simply set to true the array slot corresponding to this region.
677 void register_young_region_with_in_cset_fast_test(HeapRegion* r) {
678 _in_cset_fast_test.set_in_young(r->hrm_index());
679 }
680 void register_old_region_with_in_cset_fast_test(HeapRegion* r) {
681 _in_cset_fast_test.set_in_old(r->hrm_index());
682 }
683
684 // This is a fast test on whether a reference points into the
685 // collection set or not. Assume that the reference
686 // points into the heap.
687 inline bool in_cset_fast_test(oop obj);
688
689 void clear_cset_fast_test() {
690 _in_cset_fast_test.clear();
691 }
692
693 // This is called at the start of either a concurrent cycle or a Full
694 // GC to update the number of old marking cycles started.
695 void increment_old_marking_cycles_started();
696
697 // This is called at the end of either a concurrent cycle or a Full
698 // GC to update the number of old marking cycles completed. Those two
699 // can happen in a nested fashion, i.e., we start a concurrent
700 // cycle, a Full GC happens half-way through it which ends first,
701 // and then the cycle notices that a Full GC happened and ends
702 // too. The concurrent parameter is a boolean to help us do a bit
703 // tighter consistency checking in the method. If concurrent is
704 // false, the caller is the inner caller in the nesting (i.e., the
705 // Full GC). If concurrent is true, the caller is the outer caller
706 // in this nesting (i.e., the concurrent cycle). Further nesting is
707 // not currently supported. The end of this call also notifies
708 // the FullGCCount_lock in case a Java thread is waiting for a full
709 // GC to happen (e.g., it called System.gc() with
710 // +ExplicitGCInvokesConcurrent).
711 void increment_old_marking_cycles_completed(bool concurrent);
712
713 uint old_marking_cycles_completed() {
714 return _old_marking_cycles_completed;
715 }
716
717 void register_concurrent_cycle_start(const Ticks& start_time);
718 void register_concurrent_cycle_end();
719 void trace_heap_after_concurrent_cycle();
720
721 G1YCType yc_type();
722
723 G1HRPrinter* hr_printer() { return &_hr_printer; }
724
725 // Frees a non-humongous region by initializing its contents and
726 // adding it to the free list that's passed as a parameter (this is
727 // usually a local list which will be appended to the master free
728 // list later). The used bytes of freed regions are accumulated in
729 // pre_used. If par is true, the region's RSet will not be freed
730 // up. The assumption is that this will be done later.
731 // The locked parameter indicates if the caller has already taken
732 // care of proper synchronization. This may allow some optimizations.
733 void free_region(HeapRegion* hr,
734 FreeRegionList* free_list,
735 bool par,
736 bool locked = false);
737
738 // Frees a humongous region by collapsing it into individual regions
739 // and calling free_region() for each of them. The freed regions
740 // will be added to the free list that's passed as a parameter (this
741 // is usually a local list which will be appended to the master free
742 // list later). The used bytes of freed regions are accumulated in
743 // pre_used. If par is true, the region's RSet will not be freed
744 // up. The assumption is that this will be done later.
745 void free_humongous_region(HeapRegion* hr,
746 FreeRegionList* free_list,
747 bool par);
748 protected:
749
750 // Shrink the garbage-first heap by at most the given size (in bytes!).
751 // (Rounds down to a HeapRegion boundary.)
752 virtual void shrink(size_t expand_bytes);
753 void shrink_helper(size_t expand_bytes);
754
755 #if TASKQUEUE_STATS
756 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
757 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
758 void reset_taskqueue_stats();
759 #endif // TASKQUEUE_STATS
760
761 // Schedule the VM operation that will do an evacuation pause to
762 // satisfy an allocation request of word_size. *succeeded will
763 // return whether the VM operation was successful (it did do an
764 // evacuation pause) or not (another thread beat us to it or the GC
765 // locker was active). Given that we should not be holding the
766 // Heap_lock when we enter this method, we will pass the
767 // gc_count_before (i.e., total_collections()) as a parameter since
768 // it has to be read while holding the Heap_lock. Currently, both
769 // methods that call do_collection_pause() release the Heap_lock
770 // before the call, so it's easy to read gc_count_before just before.
771 HeapWord* do_collection_pause(size_t word_size,
772 uint gc_count_before,
773 bool* succeeded,
774 GCCause::Cause gc_cause);
775
776 // The guts of the incremental collection pause, executed by the vm
777 // thread. It returns false if it is unable to do the collection due
778 // to the GC locker being active, true otherwise
779 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
780
781 // Actually do the work of evacuating the collection set.
782 void evacuate_collection_set(EvacuationInfo& evacuation_info);
783
784 // The g1 remembered set of the heap.
785 G1RemSet* _g1_rem_set;
786
787 // A set of cards that cover the objects for which the Rsets should be updated
788 // concurrently after the collection.
789 DirtyCardQueueSet _dirty_card_queue_set;
790
791 // The closure used to refine a single card.
792 RefineCardTableEntryClosure* _refine_cte_cl;
793
794 // A function to check the consistency of dirty card logs.
795 void check_ct_logs_at_safepoint();
796
797 // A DirtyCardQueueSet that is used to hold cards that contain
798 // references into the current collection set. This is used to
799 // update the remembered sets of the regions in the collection
800 // set in the event of an evacuation failure.
801 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
802
803 // After a collection pause, make the regions in the CS into free
804 // regions.
805 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
806
807 // Abandon the current collection set without recording policy
808 // statistics or updating free lists.
809 void abandon_collection_set(HeapRegion* cs_head);
810
811 // The concurrent marker (and the thread it runs in.)
812 ConcurrentMark* _cm;
813 ConcurrentMarkThread* _cmThread;
814 bool _mark_in_progress;
815
816 // The concurrent refiner.
817 ConcurrentG1Refine* _cg1r;
818
819 // The parallel task queues
820 RefToScanQueueSet *_task_queues;
821
822 // True iff a evacuation has failed in the current collection.
823 bool _evacuation_failed;
824
825 EvacuationFailedInfo* _evacuation_failed_info_array;
826
827 // Failed evacuations cause some logical from-space objects to have
828 // forwarding pointers to themselves. Reset them.
829 void remove_self_forwarding_pointers();
830
831 // Together, these store an object with a preserved mark, and its mark value.
832 Stack<oop, mtGC> _objs_with_preserved_marks;
833 Stack<markOop, mtGC> _preserved_marks_of_objs;
834
835 // Preserve the mark of "obj", if necessary, in preparation for its mark
836 // word being overwritten with a self-forwarding-pointer.
837 void preserve_mark_if_necessary(oop obj, markOop m);
838
839 // The stack of evac-failure objects left to be scanned.
840 GrowableArray<oop>* _evac_failure_scan_stack;
841 // The closure to apply to evac-failure objects.
842
843 OopsInHeapRegionClosure* _evac_failure_closure;
844 // Set the field above.
845 void
846 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
847 _evac_failure_closure = evac_failure_closure;
848 }
849
850 // Push "obj" on the scan stack.
851 void push_on_evac_failure_scan_stack(oop obj);
852 // Process scan stack entries until the stack is empty.
853 void drain_evac_failure_scan_stack();
854 // True iff an invocation of "drain_scan_stack" is in progress; to
855 // prevent unnecessary recursion.
856 bool _drain_in_progress;
857
858 // Do any necessary initialization for evacuation-failure handling.
859 // "cl" is the closure that will be used to process evac-failure
860 // objects.
861 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
862 // Do any necessary cleanup for evacuation-failure handling data
863 // structures.
864 void finalize_for_evac_failure();
865
866 // An attempt to evacuate "obj" has failed; take necessary steps.
867 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
868 void handle_evacuation_failure_common(oop obj, markOop m);
869
870 #ifndef PRODUCT
871 // Support for forcing evacuation failures. Analogous to
872 // PromotionFailureALot for the other collectors.
873
874 // Records whether G1EvacuationFailureALot should be in effect
875 // for the current GC
876 bool _evacuation_failure_alot_for_current_gc;
877
878 // Used to record the GC number for interval checking when
879 // determining whether G1EvaucationFailureALot is in effect
880 // for the current GC.
881 size_t _evacuation_failure_alot_gc_number;
882
883 // Count of the number of evacuations between failures.
884 volatile size_t _evacuation_failure_alot_count;
885
886 // Set whether G1EvacuationFailureALot should be in effect
887 // for the current GC (based upon the type of GC and which
888 // command line flags are set);
889 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
890 bool during_initial_mark,
891 bool during_marking);
892
893 inline void set_evacuation_failure_alot_for_current_gc();
894
895 // Return true if it's time to cause an evacuation failure.
896 inline bool evacuation_should_fail();
897
898 // Reset the G1EvacuationFailureALot counters. Should be called at
899 // the end of an evacuation pause in which an evacuation failure occurred.
900 inline void reset_evacuation_should_fail();
901 #endif // !PRODUCT
902
903 // ("Weak") Reference processing support.
904 //
905 // G1 has 2 instances of the reference processor class. One
906 // (_ref_processor_cm) handles reference object discovery
907 // and subsequent processing during concurrent marking cycles.
908 //
909 // The other (_ref_processor_stw) handles reference object
910 // discovery and processing during full GCs and incremental
911 // evacuation pauses.
912 //
913 // During an incremental pause, reference discovery will be
914 // temporarily disabled for _ref_processor_cm and will be
915 // enabled for _ref_processor_stw. At the end of the evacuation
916 // pause references discovered by _ref_processor_stw will be
917 // processed and discovery will be disabled. The previous
918 // setting for reference object discovery for _ref_processor_cm
919 // will be re-instated.
920 //
921 // At the start of marking:
922 // * Discovery by the CM ref processor is verified to be inactive
923 // and it's discovered lists are empty.
924 // * Discovery by the CM ref processor is then enabled.
925 //
926 // At the end of marking:
927 // * Any references on the CM ref processor's discovered
928 // lists are processed (possibly MT).
929 //
930 // At the start of full GC we:
931 // * Disable discovery by the CM ref processor and
932 // empty CM ref processor's discovered lists
933 // (without processing any entries).
934 // * Verify that the STW ref processor is inactive and it's
935 // discovered lists are empty.
936 // * Temporarily set STW ref processor discovery as single threaded.
937 // * Temporarily clear the STW ref processor's _is_alive_non_header
938 // field.
939 // * Finally enable discovery by the STW ref processor.
940 //
941 // The STW ref processor is used to record any discovered
942 // references during the full GC.
943 //
944 // At the end of a full GC we:
945 // * Enqueue any reference objects discovered by the STW ref processor
946 // that have non-live referents. This has the side-effect of
947 // making the STW ref processor inactive by disabling discovery.
948 // * Verify that the CM ref processor is still inactive
949 // and no references have been placed on it's discovered
950 // lists (also checked as a precondition during initial marking).
951
952 // The (stw) reference processor...
953 ReferenceProcessor* _ref_processor_stw;
954
955 STWGCTimer* _gc_timer_stw;
956 ConcurrentGCTimer* _gc_timer_cm;
957
958 G1OldTracer* _gc_tracer_cm;
959 G1NewTracer* _gc_tracer_stw;
960
961 // During reference object discovery, the _is_alive_non_header
962 // closure (if non-null) is applied to the referent object to
963 // determine whether the referent is live. If so then the
964 // reference object does not need to be 'discovered' and can
965 // be treated as a regular oop. This has the benefit of reducing
966 // the number of 'discovered' reference objects that need to
967 // be processed.
968 //
969 // Instance of the is_alive closure for embedding into the
970 // STW reference processor as the _is_alive_non_header field.
971 // Supplying a value for the _is_alive_non_header field is
972 // optional but doing so prevents unnecessary additions to
973 // the discovered lists during reference discovery.
974 G1STWIsAliveClosure _is_alive_closure_stw;
975
976 // The (concurrent marking) reference processor...
977 ReferenceProcessor* _ref_processor_cm;
978
979 // Instance of the concurrent mark is_alive closure for embedding
980 // into the Concurrent Marking reference processor as the
981 // _is_alive_non_header field. Supplying a value for the
982 // _is_alive_non_header field is optional but doing so prevents
983 // unnecessary additions to the discovered lists during reference
984 // discovery.
985 G1CMIsAliveClosure _is_alive_closure_cm;
986
987 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
988 HeapRegion** _worker_cset_start_region;
989
990 // Time stamp to validate the regions recorded in the cache
991 // used by G1CollectedHeap::start_cset_region_for_worker().
992 // The heap region entry for a given worker is valid iff
993 // the associated time stamp value matches the current value
994 // of G1CollectedHeap::_gc_time_stamp.
995 uint* _worker_cset_start_region_time_stamp;
996
997 volatile bool _free_regions_coming;
998
999 public:
1000
1001 void set_refine_cte_cl_concurrency(bool concurrent);
1002
1003 RefToScanQueue *task_queue(int i) const;
1004
1005 // A set of cards where updates happened during the GC
1006 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
1007
1008 // A DirtyCardQueueSet that is used to hold cards that contain
1009 // references into the current collection set. This is used to
1010 // update the remembered sets of the regions in the collection
1011 // set in the event of an evacuation failure.
1012 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
1013 { return _into_cset_dirty_card_queue_set; }
1014
1015 // Create a G1CollectedHeap with the specified policy.
1016 // Must call the initialize method afterwards.
1017 // May not return if something goes wrong.
1018 G1CollectedHeap(G1CollectorPolicy* policy);
1019
1020 // Initialize the G1CollectedHeap to have the initial and
1021 // maximum sizes and remembered and barrier sets
1022 // specified by the policy object.
1023 jint initialize();
1024
1025 virtual void stop();
1026
1027 // Return the (conservative) maximum heap alignment for any G1 heap
1028 static size_t conservative_max_heap_alignment();
1029
1030 // Initialize weak reference processing.
1031 virtual void ref_processing_init();
1032
1033 // Explicitly import set_par_threads into this scope
1034 using SharedHeap::set_par_threads;
1035 // Set _n_par_threads according to a policy TBD.
1036 void set_par_threads();
1037
1038 virtual CollectedHeap::Name kind() const {
1039 return CollectedHeap::G1CollectedHeap;
1040 }
1041
1042 // The current policy object for the collector.
1043 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1044
1045 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1046
1047 // Adaptive size policy. No such thing for g1.
1048 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1049
1050 // The rem set and barrier set.
1051 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1052
1053 unsigned get_gc_time_stamp() {
1054 return _gc_time_stamp;
1055 }
1056
1057 inline void reset_gc_time_stamp();
1058
1059 void check_gc_time_stamps() PRODUCT_RETURN;
1060
1061 inline void increment_gc_time_stamp();
1062
1063 // Reset the given region's GC timestamp. If it's starts humongous,
1064 // also reset the GC timestamp of its corresponding
1065 // continues humongous regions too.
1066 void reset_gc_time_stamps(HeapRegion* hr);
1067
1068 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1069 DirtyCardQueue* into_cset_dcq,
1070 bool concurrent, uint worker_i);
1071
1072 // The shared block offset table array.
1073 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1074
1075 // Reference Processing accessors
1076
1077 // The STW reference processor....
1078 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1079
1080 // The Concurrent Marking reference processor...
1081 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1082
1083 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1084 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1085
1086 virtual size_t capacity() const;
1087 virtual size_t used() const;
1088 // This should be called when we're not holding the heap lock. The
1089 // result might be a bit inaccurate.
1090 size_t used_unlocked() const;
1091 size_t recalculate_used() const;
1092
1093 // These virtual functions do the actual allocation.
1094 // Some heaps may offer a contiguous region for shared non-blocking
1095 // allocation, via inlined code (by exporting the address of the top and
1096 // end fields defining the extent of the contiguous allocation region.)
1097 // But G1CollectedHeap doesn't yet support this.
1098
1099 virtual bool is_maximal_no_gc() const {
1100 return _hrm.available() == 0;
1101 }
1102
1103 // The current number of regions in the heap.
1104 uint num_regions() const { return _hrm.length(); }
1105
1106 // The max number of regions in the heap.
1107 uint max_regions() const { return _hrm.max_length(); }
1108
1109 // The number of regions that are completely free.
1110 uint num_free_regions() const { return _hrm.num_free_regions(); }
1111
1112 MemoryUsage get_auxiliary_data_memory_usage() const {
1113 return _hrm.get_auxiliary_data_memory_usage();
1114 }
1115
1116 // The number of regions that are not completely free.
1117 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1118
1119 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1120 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1121 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1122 void verify_dirty_young_regions() PRODUCT_RETURN;
1123
1124 #ifndef PRODUCT
1125 // Make sure that the given bitmap has no marked objects in the
1126 // range [from,limit). If it does, print an error message and return
1127 // false. Otherwise, just return true. bitmap_name should be "prev"
1128 // or "next".
1129 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1130 HeapWord* from, HeapWord* limit);
1131
1132 // Verify that the prev / next bitmap range [tams,end) for the given
1133 // region has no marks. Return true if all is well, false if errors
1134 // are detected.
1135 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1136 #endif // PRODUCT
1137
1138 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1139 // the given region do not have any spurious marks. If errors are
1140 // detected, print appropriate error messages and crash.
1141 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1142
1143 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1144 // have any spurious marks. If errors are detected, print
1145 // appropriate error messages and crash.
1146 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1147
1148 // Do sanity check on the contents of the in-cset fast test table.
1149 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1150
1151 // verify_region_sets() performs verification over the region
1152 // lists. It will be compiled in the product code to be used when
1153 // necessary (i.e., during heap verification).
1154 void verify_region_sets();
1155
1156 // verify_region_sets_optional() is planted in the code for
1157 // list verification in non-product builds (and it can be enabled in
1158 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1159 #if HEAP_REGION_SET_FORCE_VERIFY
1160 void verify_region_sets_optional() {
1161 verify_region_sets();
1162 }
1163 #else // HEAP_REGION_SET_FORCE_VERIFY
1164 void verify_region_sets_optional() { }
1165 #endif // HEAP_REGION_SET_FORCE_VERIFY
1166
1167 #ifdef ASSERT
1168 bool is_on_master_free_list(HeapRegion* hr) {
1169 return _hrm.is_free(hr);
1170 }
1171 #endif // ASSERT
1172
1173 // Wrapper for the region list operations that can be called from
1174 // methods outside this class.
1175
1176 void secondary_free_list_add(FreeRegionList* list) {
1177 _secondary_free_list.add_ordered(list);
1178 }
1179
1180 void append_secondary_free_list() {
1181 _hrm.insert_list_into_free_list(&_secondary_free_list);
1182 }
1183
1184 void append_secondary_free_list_if_not_empty_with_lock() {
1185 // If the secondary free list looks empty there's no reason to
1186 // take the lock and then try to append it.
1187 if (!_secondary_free_list.is_empty()) {
1188 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1189 append_secondary_free_list();
1190 }
1191 }
1192
1193 inline void old_set_remove(HeapRegion* hr);
1194
1195 size_t non_young_capacity_bytes() {
1196 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1197 }
1198
1199 void set_free_regions_coming();
1200 void reset_free_regions_coming();
1201 bool free_regions_coming() { return _free_regions_coming; }
1202 void wait_while_free_regions_coming();
1203
1204 // Determine whether the given region is one that we are using as an
1205 // old GC alloc region.
1206 bool is_old_gc_alloc_region(HeapRegion* hr) {
1207 return _allocator->is_retained_old_region(hr);
1208 }
1209
1210 // Perform a collection of the heap; intended for use in implementing
1211 // "System.gc". This probably implies as full a collection as the
1212 // "CollectedHeap" supports.
1213 virtual void collect(GCCause::Cause cause);
1214
1215 // The same as above but assume that the caller holds the Heap_lock.
1216 void collect_locked(GCCause::Cause cause);
1217
1218 virtual bool copy_allocation_context_stats(const jint* contexts,
1219 jlong* totals,
1220 jbyte* accuracy,
1221 jint len);
1222
1223 // True iff an evacuation has failed in the most-recent collection.
1224 bool evacuation_failed() { return _evacuation_failed; }
1225
1226 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1227 void prepend_to_freelist(FreeRegionList* list);
1228 void decrement_summary_bytes(size_t bytes);
1229
1230 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1231 virtual bool is_in(const void* p) const;
1232 #ifdef ASSERT
1233 // Returns whether p is in one of the available areas of the heap. Slow but
1234 // extensive version.
1235 bool is_in_exact(const void* p) const;
1236 #endif
1237
1238 // Return "TRUE" iff the given object address is within the collection
1239 // set. Slow implementation.
1240 inline bool obj_in_cs(oop obj);
1241
1242 inline bool is_in_cset(oop obj);
1243
1244 inline bool is_in_cset_or_humongous(const oop obj);
1245
1246 private:
1247 // This array is used for a quick test on whether a reference points into
1248 // the collection set or not. Each of the array's elements denotes whether the
1249 // corresponding region is in the collection set or not.
1250 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1251
1252 public:
1253
1254 inline InCSetState in_cset_state(const oop obj);
1255
1256 // Return "TRUE" iff the given object address is in the reserved
1257 // region of g1.
1258 bool is_in_g1_reserved(const void* p) const {
1259 return _hrm.reserved().contains(p);
1260 }
1261
1262 // Returns a MemRegion that corresponds to the space that has been
1263 // reserved for the heap
1264 MemRegion g1_reserved() const {
1265 return _hrm.reserved();
1266 }
1267
1268 virtual bool is_in_closed_subset(const void* p) const;
1269
1270 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1271 return (G1SATBCardTableLoggingModRefBS*) barrier_set();
1272 }
1273
1274 // This resets the card table to all zeros. It is used after
1275 // a collection pause which used the card table to claim cards.
1276 void cleanUpCardTable();
1277
1278 // Iteration functions.
1279
1280 // Iterate over all the ref-containing fields of all objects, calling
1281 // "cl.do_oop" on each.
1282 virtual void oop_iterate(ExtendedOopClosure* cl);
1283
1284 // Iterate over all objects, calling "cl.do_object" on each.
1285 virtual void object_iterate(ObjectClosure* cl);
1286
1287 virtual void safe_object_iterate(ObjectClosure* cl) {
1288 object_iterate(cl);
1289 }
1290
1291 // Iterate over all spaces in use in the heap, in ascending address order.
1292 virtual void space_iterate(SpaceClosure* cl);
1293
1294 // Iterate over heap regions, in address order, terminating the
1295 // iteration early if the "doHeapRegion" method returns "true".
1296 void heap_region_iterate(HeapRegionClosure* blk) const;
1297
1298 // Return the region with the given index. It assumes the index is valid.
1299 inline HeapRegion* region_at(uint index) const;
1300
1301 // Calculate the region index of the given address. Given address must be
1302 // within the heap.
1303 inline uint addr_to_region(HeapWord* addr) const;
1304
1305 inline HeapWord* bottom_addr_for_region(uint index) const;
1306
1307 // Divide the heap region sequence into "chunks" of some size (the number
1308 // of regions divided by the number of parallel threads times some
1309 // overpartition factor, currently 4). Assumes that this will be called
1310 // in parallel by ParallelGCThreads worker threads with discinct worker
1311 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1312 // calls will use the same "claim_value", and that that claim value is
1313 // different from the claim_value of any heap region before the start of
1314 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1315 // attempting to claim the first region in each chunk, and, if
1316 // successful, applying the closure to each region in the chunk (and
1317 // setting the claim value of the second and subsequent regions of the
1318 // chunk.) For now requires that "doHeapRegion" always returns "false",
1319 // i.e., that a closure never attempt to abort a traversal.
1320 void heap_region_par_iterate_chunked(HeapRegionClosure* cl,
1321 uint worker_id,
1322 uint num_workers,
1323 jint claim_value) const;
1324
1325 // It resets all the region claim values to the default.
1326 void reset_heap_region_claim_values();
1327
1328 // Resets the claim values of regions in the current
1329 // collection set to the default.
1330 void reset_cset_heap_region_claim_values();
1331
1332 #ifdef ASSERT
1333 bool check_heap_region_claim_values(jint claim_value);
1334
1335 // Same as the routine above but only checks regions in the
1336 // current collection set.
1337 bool check_cset_heap_region_claim_values(jint claim_value);
1338 #endif // ASSERT
1339
1340 // Clear the cached cset start regions and (more importantly)
1341 // the time stamps. Called when we reset the GC time stamp.
1342 void clear_cset_start_regions();
1343
1344 // Given the id of a worker, obtain or calculate a suitable
1345 // starting region for iterating over the current collection set.
1346 HeapRegion* start_cset_region_for_worker(uint worker_i);
1347
1348 // Iterate over the regions (if any) in the current collection set.
1349 void collection_set_iterate(HeapRegionClosure* blk);
1350
1351 // As above but starting from region r
1352 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1353
1354 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1355
1356 // A CollectedHeap will contain some number of spaces. This finds the
1357 // space containing a given address, or else returns NULL.
1358 virtual Space* space_containing(const void* addr) const;
1359
1360 // Returns the HeapRegion that contains addr. addr must not be NULL.
1361 template <class T>
1362 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1363
1364 // Returns the HeapRegion that contains addr. addr must not be NULL.
1365 // If addr is within a humongous continues region, it returns its humongous start region.
1366 template <class T>
1367 inline HeapRegion* heap_region_containing(const T addr) const;
1368
1369 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1370 // each address in the (reserved) heap is a member of exactly
1371 // one block. The defining characteristic of a block is that it is
1372 // possible to find its size, and thus to progress forward to the next
1373 // block. (Blocks may be of different sizes.) Thus, blocks may
1374 // represent Java objects, or they might be free blocks in a
1375 // free-list-based heap (or subheap), as long as the two kinds are
1376 // distinguishable and the size of each is determinable.
1377
1378 // Returns the address of the start of the "block" that contains the
1379 // address "addr". We say "blocks" instead of "object" since some heaps
1380 // may not pack objects densely; a chunk may either be an object or a
1381 // non-object.
1382 virtual HeapWord* block_start(const void* addr) const;
1383
1384 // Requires "addr" to be the start of a chunk, and returns its size.
1385 // "addr + size" is required to be the start of a new chunk, or the end
1386 // of the active area of the heap.
1387 virtual size_t block_size(const HeapWord* addr) const;
1388
1389 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1390 // the block is an object.
1391 virtual bool block_is_obj(const HeapWord* addr) const;
1392
1393 // Does this heap support heap inspection? (+PrintClassHistogram)
1394 virtual bool supports_heap_inspection() const { return true; }
1395
1396 // Section on thread-local allocation buffers (TLABs)
1397 // See CollectedHeap for semantics.
1398
1399 bool supports_tlab_allocation() const;
1400 size_t tlab_capacity(Thread* ignored) const;
1401 size_t tlab_used(Thread* ignored) const;
1402 size_t max_tlab_size() const;
1403 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1404
1405 // Can a compiler initialize a new object without store barriers?
1406 // This permission only extends from the creation of a new object
1407 // via a TLAB up to the first subsequent safepoint. If such permission
1408 // is granted for this heap type, the compiler promises to call
1409 // defer_store_barrier() below on any slow path allocation of
1410 // a new object for which such initializing store barriers will
1411 // have been elided. G1, like CMS, allows this, but should be
1412 // ready to provide a compensating write barrier as necessary
1413 // if that storage came out of a non-young region. The efficiency
1414 // of this implementation depends crucially on being able to
1415 // answer very efficiently in constant time whether a piece of
1416 // storage in the heap comes from a young region or not.
1417 // See ReduceInitialCardMarks.
1418 virtual bool can_elide_tlab_store_barriers() const {
1419 return true;
1420 }
1421
1422 virtual bool card_mark_must_follow_store() const {
1423 return true;
1424 }
1425
1426 inline bool is_in_young(const oop obj);
1427
1428 #ifdef ASSERT
1429 virtual bool is_in_partial_collection(const void* p);
1430 #endif
1431
1432 virtual bool is_scavengable(const void* addr);
1433
1434 // We don't need barriers for initializing stores to objects
1435 // in the young gen: for the SATB pre-barrier, there is no
1436 // pre-value that needs to be remembered; for the remembered-set
1437 // update logging post-barrier, we don't maintain remembered set
1438 // information for young gen objects.
1439 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1440
1441 // Returns "true" iff the given word_size is "very large".
1442 static bool isHumongous(size_t word_size) {
1443 // Note this has to be strictly greater-than as the TLABs
1444 // are capped at the humongous thresold and we want to
1445 // ensure that we don't try to allocate a TLAB as
1446 // humongous and that we don't allocate a humongous
1447 // object in a TLAB.
1448 return word_size > _humongous_object_threshold_in_words;
1449 }
1450
1451 // Update mod union table with the set of dirty cards.
1452 void updateModUnion();
1453
1454 // Set the mod union bits corresponding to the given memRegion. Note
1455 // that this is always a safe operation, since it doesn't clear any
1456 // bits.
1457 void markModUnionRange(MemRegion mr);
1458
1459 // Records the fact that a marking phase is no longer in progress.
1460 void set_marking_complete() {
1461 _mark_in_progress = false;
1462 }
1463 void set_marking_started() {
1464 _mark_in_progress = true;
1465 }
1466 bool mark_in_progress() {
1467 return _mark_in_progress;
1468 }
1469
1470 // Print the maximum heap capacity.
1471 virtual size_t max_capacity() const;
1472
1473 virtual jlong millis_since_last_gc();
1474
1475
1476 // Convenience function to be used in situations where the heap type can be
1477 // asserted to be this type.
1478 static G1CollectedHeap* heap();
1479
1480 void set_region_short_lived_locked(HeapRegion* hr);
1481 // add appropriate methods for any other surv rate groups
1482
1483 YoungList* young_list() const { return _young_list; }
1484
1485 // debugging
1486 bool check_young_list_well_formed() {
1487 return _young_list->check_list_well_formed();
1488 }
1489
1490 bool check_young_list_empty(bool check_heap,
1491 bool check_sample = true);
1492
1493 // *** Stuff related to concurrent marking. It's not clear to me that so
1494 // many of these need to be public.
1495
1496 // The functions below are helper functions that a subclass of
1497 // "CollectedHeap" can use in the implementation of its virtual
1498 // functions.
1499 // This performs a concurrent marking of the live objects in a
1500 // bitmap off to the side.
1501 void doConcurrentMark();
1502
1503 bool isMarkedPrev(oop obj) const;
1504 bool isMarkedNext(oop obj) const;
1505
1506 // Determine if an object is dead, given the object and also
1507 // the region to which the object belongs. An object is dead
1508 // iff a) it was not allocated since the last mark and b) it
1509 // is not marked.
1510 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1511 return
1512 !hr->obj_allocated_since_prev_marking(obj) &&
1513 !isMarkedPrev(obj);
1514 }
1515
1516 // This function returns true when an object has been
1517 // around since the previous marking and hasn't yet
1518 // been marked during this marking.
1519 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1520 return
1521 !hr->obj_allocated_since_next_marking(obj) &&
1522 !isMarkedNext(obj);
1523 }
1524
1525 // Determine if an object is dead, given only the object itself.
1526 // This will find the region to which the object belongs and
1527 // then call the region version of the same function.
1528
1529 // Added if it is NULL it isn't dead.
1530
1531 inline bool is_obj_dead(const oop obj) const;
1532
1533 inline bool is_obj_ill(const oop obj) const;
1534
1535 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1536 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1537 bool is_marked(oop obj, VerifyOption vo);
1538 const char* top_at_mark_start_str(VerifyOption vo);
1539
1540 ConcurrentMark* concurrent_mark() const { return _cm; }
1541
1542 // Refinement
1543
1544 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1545
1546 // The dirty cards region list is used to record a subset of regions
1547 // whose cards need clearing. The list if populated during the
1548 // remembered set scanning and drained during the card table
1549 // cleanup. Although the methods are reentrant, population/draining
1550 // phases must not overlap. For synchronization purposes the last
1551 // element on the list points to itself.
1552 HeapRegion* _dirty_cards_region_list;
1553 void push_dirty_cards_region(HeapRegion* hr);
1554 HeapRegion* pop_dirty_cards_region();
1555
1556 // Optimized nmethod scanning support routines
1557
1558 // Register the given nmethod with the G1 heap
1559 virtual void register_nmethod(nmethod* nm);
1560
1561 // Unregister the given nmethod from the G1 heap
1562 virtual void unregister_nmethod(nmethod* nm);
1563
1564 // Free up superfluous code root memory.
1565 void purge_code_root_memory();
1566
1567 // Rebuild the stong code root lists for each region
1568 // after a full GC
1569 void rebuild_strong_code_roots();
1570
1571 // Delete entries for dead interned string and clean up unreferenced symbols
1572 // in symbol table, possibly in parallel.
1573 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1574
1575 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1576 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1577
1578 // Redirty logged cards in the refinement queue.
1579 void redirty_logged_cards();
1580 // Verification
1581
1582 // The following is just to alert the verification code
1583 // that a full collection has occurred and that the
1584 // remembered sets are no longer up to date.
1585 bool _full_collection;
1586 void set_full_collection() { _full_collection = true;}
1587 void clear_full_collection() {_full_collection = false;}
1588 bool full_collection() {return _full_collection;}
1589
1590 // Perform any cleanup actions necessary before allowing a verification.
1591 virtual void prepare_for_verify();
1592
1593 // Perform verification.
1594
1595 // vo == UsePrevMarking -> use "prev" marking information,
1596 // vo == UseNextMarking -> use "next" marking information
1597 // vo == UseMarkWord -> use the mark word in the object header
1598 //
1599 // NOTE: Only the "prev" marking information is guaranteed to be
1600 // consistent most of the time, so most calls to this should use
1601 // vo == UsePrevMarking.
1602 // Currently, there is only one case where this is called with
1603 // vo == UseNextMarking, which is to verify the "next" marking
1604 // information at the end of remark.
1605 // Currently there is only one place where this is called with
1606 // vo == UseMarkWord, which is to verify the marking during a
1607 // full GC.
1608 void verify(bool silent, VerifyOption vo);
1609
1610 // Override; it uses the "prev" marking information
1611 virtual void verify(bool silent);
1612
1613 // The methods below are here for convenience and dispatch the
1614 // appropriate method depending on value of the given VerifyOption
1615 // parameter. The values for that parameter, and their meanings,
1616 // are the same as those above.
1617
1618 bool is_obj_dead_cond(const oop obj,
1619 const HeapRegion* hr,
1620 const VerifyOption vo) const;
1621
1622 bool is_obj_dead_cond(const oop obj,
1623 const VerifyOption vo) const;
1624
1625 // Printing
1626
1627 virtual void print_on(outputStream* st) const;
1628 virtual void print_extended_on(outputStream* st) const;
1629 virtual void print_on_error(outputStream* st) const;
1630
1631 virtual void print_gc_threads_on(outputStream* st) const;
1632 virtual void gc_threads_do(ThreadClosure* tc) const;
1633
1634 // Override
1635 void print_tracing_info() const;
1636
1637 // The following two methods are helpful for debugging RSet issues.
1638 void print_cset_rsets() PRODUCT_RETURN;
1639 void print_all_rsets() PRODUCT_RETURN;
1640
1641 public:
1642 size_t pending_card_num();
1643 size_t cards_scanned();
1644
1645 protected:
1646 size_t _max_heap_capacity;
1647 };
1648
1649 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP