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/g1EvacStats.hpp"
38 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
39 #include "gc_implementation/g1/g1YCTypes.hpp"
40 #include "gc_implementation/g1/heapRegionManager.hpp"
41 #include "gc_implementation/g1/heapRegionSet.hpp"
42 #include "gc_implementation/shared/hSpaceCounters.hpp"
43 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
44 #include "memory/barrierSet.hpp"
45 #include "memory/memRegion.hpp"
46 #include "memory/sharedHeap.hpp"
47 #include "utilities/stack.hpp"
48
49 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
50 // It uses the "Garbage First" heap organization and algorithm, which
51 // may combine concurrent marking with parallel, incremental compaction of
52 // heap subsets that will yield large amounts of garbage.
53
54 // Forward declarations
55 class HeapRegion;
56 class HRRSCleanupTask;
57 class GenerationSpec;
58 class OopsInHeapRegionClosure;
59 class G1ParScanThreadState;
60 class G1KlassScanClosure;
61 class ObjectClosure;
62 class SpaceClosure;
63 class CompactibleSpaceClosure;
64 class Space;
65 class G1CollectorPolicy;
66 class GenRemSet;
67 class G1RemSet;
68 class HeapRegionRemSetIterator;
69 class ConcurrentMark;
70 class ConcurrentMarkThread;
71 class ConcurrentG1Refine;
72 class ConcurrentGCTimer;
73 class GenerationCounters;
74 class STWGCTimer;
75 class G1NewTracer;
76 class G1OldTracer;
77 class EvacuationFailedInfo;
78 class nmethod;
79 class Ticks;
80
81 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
82 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
83
84 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
85 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
86
87 class YoungList : public CHeapObj<mtGC> {
88 private:
89 G1CollectedHeap* _g1h;
90
91 HeapRegion* _head;
92
93 HeapRegion* _survivor_head;
94 HeapRegion* _survivor_tail;
95
96 HeapRegion* _curr;
97
98 uint _length;
99 uint _survivor_length;
100
101 size_t _last_sampled_rs_lengths;
102 size_t _sampled_rs_lengths;
103
104 void empty_list(HeapRegion* list);
105
106 public:
107 YoungList(G1CollectedHeap* g1h);
108
109 void push_region(HeapRegion* hr);
110 void add_survivor_region(HeapRegion* hr);
111
112 void empty_list();
113 bool is_empty() { return _length == 0; }
114 uint length() { return _length; }
115 uint survivor_length() { return _survivor_length; }
116
117 // Currently we do not keep track of the used byte sum for the
118 // young list and the survivors and it'd be quite a lot of work to
119 // do so. When we'll eventually replace the young list with
120 // instances of HeapRegionLinkedList we'll get that for free. So,
121 // we'll report the more accurate information then.
122 size_t eden_used_bytes() {
123 assert(length() >= survivor_length(), "invariant");
124 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes;
125 }
126 size_t survivor_used_bytes() {
127 return (size_t) survivor_length() * HeapRegion::GrainBytes;
128 }
129
130 void rs_length_sampling_init();
131 bool rs_length_sampling_more();
132 void rs_length_sampling_next();
133
134 void reset_sampled_info() {
135 _last_sampled_rs_lengths = 0;
136 }
137 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
138
139 // for development purposes
140 void reset_auxilary_lists();
141 void clear() { _head = NULL; _length = 0; }
142
143 void clear_survivors() {
144 _survivor_head = NULL;
145 _survivor_tail = NULL;
146 _survivor_length = 0;
147 }
148
149 HeapRegion* first_region() { return _head; }
150 HeapRegion* first_survivor_region() { return _survivor_head; }
151 HeapRegion* last_survivor_region() { return _survivor_tail; }
152
153 // debugging
154 bool check_list_well_formed();
155 bool check_list_empty(bool check_sample = true);
156 void print();
157 };
158
159 // The G1 STW is alive closure.
160 // An instance is embedded into the G1CH and used as the
161 // (optional) _is_alive_non_header closure in the STW
162 // reference processor. It is also extensively used during
163 // reference processing during STW evacuation pauses.
164 class G1STWIsAliveClosure: public BoolObjectClosure {
165 G1CollectedHeap* _g1;
166 public:
167 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
168 bool do_object_b(oop p);
169 };
170
171 class RefineCardTableEntryClosure;
172
173 class G1RegionMappingChangedListener : public G1MappingChangedListener {
174 private:
175 void reset_from_card_cache(uint start_idx, size_t num_regions);
176 public:
177 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
178 };
179
180 class G1CollectedHeap : public SharedHeap {
181 friend class VM_CollectForMetadataAllocation;
182 friend class VM_G1CollectForAllocation;
183 friend class VM_G1CollectFull;
184 friend class VM_G1IncCollectionPause;
185 friend class VMStructs;
186
187 // Closures used in implementation.
188 friend class G1ParScanThreadState;
189 friend class G1ParTask;
190 friend class G1PrepareCompactClosure;
191
192 // Other related classes.
193 friend class HeapRegionClaimer;
194
195 // Testing classes.
196 friend class G1CheckCSetFastTableClosure;
197
198 private:
199 // The one and only G1CollectedHeap, so static functions can find it.
200 static G1CollectedHeap* _g1h;
201
202 static size_t _humongous_object_threshold_in_words;
203
204 // The secondary free list which contains regions that have been
205 // freed up during the cleanup process. This will be appended to
206 // the master free list when appropriate.
207 FreeRegionList _secondary_free_list;
208
209 // It keeps track of the old regions.
210 HeapRegionSet _old_set;
211
212 // It keeps track of the humongous regions.
213 HeapRegionSet _humongous_set;
214
215 void clear_humongous_is_live_table();
216 void eagerly_reclaim_humongous_regions();
217
218 // The number of regions we could create by expansion.
219 uint _expansion_regions;
220
221 // The block offset table for the G1 heap.
222 G1BlockOffsetSharedArray* _bot_shared;
223
224 // Tears down the region sets / lists so that they are empty and the
225 // regions on the heap do not belong to a region set / list. The
226 // only exception is the humongous set which we leave unaltered. If
227 // free_list_only is true, it will only tear down the master free
228 // list. It is called before a Full GC (free_list_only == false) or
229 // before heap shrinking (free_list_only == true).
230 void tear_down_region_sets(bool free_list_only);
231
232 // Rebuilds the region sets / lists so that they are repopulated to
233 // reflect the contents of the heap. The only exception is the
234 // humongous set which was not torn down in the first place. If
235 // free_list_only is true, it will only rebuild the master free
236 // list. It is called after a Full GC (free_list_only == false) or
237 // after heap shrinking (free_list_only == true).
238 void rebuild_region_sets(bool free_list_only);
239
240 // Callback for region mapping changed events.
241 G1RegionMappingChangedListener _listener;
242
243 // The sequence of all heap regions in the heap.
244 HeapRegionManager _hrm;
245
246 // Manages all kinds of allocations within regions. This excludes only
247 // humongous object allocations.
248 G1Allocator* _allocator;
249
250 // Outside of GC pauses, the number of bytes used in all regions other
251 // than the current allocation region(s).
252 size_t _summary_bytes_used;
253
254 // Statistics for each allocation context
255 AllocationContextStats _allocation_context_stats;
256
257 // It specifies whether we should attempt to expand the heap after a
258 // region allocation failure. If heap expansion fails we set this to
259 // false so that we don't re-attempt the heap expansion (it's likely
260 // that subsequent expansion attempts will also fail if one fails).
261 // Currently, it is only consulted during GC and it's reset at the
262 // start of each GC.
263 bool _expand_heap_after_alloc_failure;
264
265 // Helper for monitoring and management support.
266 G1MonitoringSupport* _g1mm;
267
268 // Records whether the region at the given index is kept live by roots or
269 // references from the young generation.
270 class HumongousIsLiveBiasedMappedArray : public G1BiasedMappedArray<bool> {
271 protected:
272 bool default_value() const { return false; }
273 public:
274 void clear() { G1BiasedMappedArray<bool>::clear(); }
275 void set_live(uint region) {
276 set_by_index(region, true);
277 }
278 bool is_live(uint region) {
279 return get_by_index(region);
280 }
281 };
282
283 HumongousIsLiveBiasedMappedArray _humongous_is_live;
284 // Stores whether during humongous object registration we found candidate regions.
285 // If not, we can skip a few steps.
286 bool _has_humongous_reclaim_candidates;
287
288 volatile unsigned _gc_time_stamp;
289
290 size_t* _surviving_young_words;
291
292 G1HRPrinter _hr_printer;
293
294 void setup_surviving_young_words();
295 void update_surviving_young_words(size_t* surv_young_words);
296 void cleanup_surviving_young_words();
297
298 // It decides whether an explicit GC should start a concurrent cycle
299 // instead of doing a STW GC. Currently, a concurrent cycle is
300 // explicitly started if:
301 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
302 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
303 // (c) cause == _g1_humongous_allocation
304 bool should_do_concurrent_full_gc(GCCause::Cause cause);
305
306 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
307 // concurrent cycles) we have started.
308 volatile uint _old_marking_cycles_started;
309
310 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
311 // concurrent cycles) we have completed.
312 volatile uint _old_marking_cycles_completed;
313
314 bool _concurrent_cycle_started;
315 bool _heap_summary_sent;
316
317 // This is a non-product method that is helpful for testing. It is
318 // called at the end of a GC and artificially expands the heap by
319 // allocating a number of dead regions. This way we can induce very
320 // frequent marking cycles and stress the cleanup / concurrent
321 // cleanup code more (as all the regions that will be allocated by
322 // this method will be found dead by the marking cycle).
323 void allocate_dummy_regions() PRODUCT_RETURN;
324
325 // Clear RSets after a compaction. It also resets the GC time stamps.
326 void clear_rsets_post_compaction();
327
328 // If the HR printer is active, dump the state of the regions in the
329 // heap after a compaction.
330 void print_hrm_post_compaction();
331
332 double verify(bool guard, const char* msg);
333 void verify_before_gc();
334 void verify_after_gc();
335
336 void log_gc_header();
337 void log_gc_footer(double pause_time_sec);
338
339 // These are macros so that, if the assert fires, we get the correct
340 // line number, file, etc.
341
342 #define heap_locking_asserts_err_msg(_extra_message_) \
343 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
344 (_extra_message_), \
345 BOOL_TO_STR(Heap_lock->owned_by_self()), \
346 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
347 BOOL_TO_STR(Thread::current()->is_VM_thread()))
348
349 #define assert_heap_locked() \
350 do { \
351 assert(Heap_lock->owned_by_self(), \
352 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
353 } while (0)
354
355 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
356 do { \
357 assert(Heap_lock->owned_by_self() || \
358 (SafepointSynchronize::is_at_safepoint() && \
359 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
360 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
361 "should be at a safepoint")); \
362 } while (0)
363
364 #define assert_heap_locked_and_not_at_safepoint() \
365 do { \
366 assert(Heap_lock->owned_by_self() && \
367 !SafepointSynchronize::is_at_safepoint(), \
368 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
369 "should not be at a safepoint")); \
370 } while (0)
371
372 #define assert_heap_not_locked() \
373 do { \
374 assert(!Heap_lock->owned_by_self(), \
375 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
376 } while (0)
377
378 #define assert_heap_not_locked_and_not_at_safepoint() \
379 do { \
380 assert(!Heap_lock->owned_by_self() && \
381 !SafepointSynchronize::is_at_safepoint(), \
382 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
383 "should not be at a safepoint")); \
384 } while (0)
385
386 #define assert_at_safepoint(_should_be_vm_thread_) \
387 do { \
388 assert(SafepointSynchronize::is_at_safepoint() && \
389 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
390 heap_locking_asserts_err_msg("should be at a safepoint")); \
391 } while (0)
392
393 #define assert_not_at_safepoint() \
394 do { \
395 assert(!SafepointSynchronize::is_at_safepoint(), \
396 heap_locking_asserts_err_msg("should not be at a safepoint")); \
397 } while (0)
398
399 protected:
400
401 // The young region list.
402 YoungList* _young_list;
403
404 // The current policy object for the collector.
405 G1CollectorPolicy* _g1_policy;
406
407 // This is the second level of trying to allocate a new region. If
408 // new_region() didn't find a region on the free_list, this call will
409 // check whether there's anything available on the
410 // secondary_free_list and/or wait for more regions to appear on
411 // that list, if _free_regions_coming is set.
412 HeapRegion* new_region_try_secondary_free_list(bool is_old);
413
414 // Try to allocate a single non-humongous HeapRegion sufficient for
415 // an allocation of the given word_size. If do_expand is true,
416 // attempt to expand the heap if necessary to satisfy the allocation
417 // request. If the region is to be used as an old region or for a
418 // humongous object, set is_old to true. If not, to false.
419 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
420
421 // Initialize a contiguous set of free regions of length num_regions
422 // and starting at index first so that they appear as a single
423 // humongous region.
424 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
425 uint num_regions,
426 size_t word_size,
427 AllocationContext_t context);
428
429 // Attempt to allocate a humongous object of the given size. Return
430 // NULL if unsuccessful.
431 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
432
433 // The following two methods, allocate_new_tlab() and
434 // mem_allocate(), are the two main entry points from the runtime
435 // into the G1's allocation routines. They have the following
436 // assumptions:
437 //
438 // * They should both be called outside safepoints.
439 //
440 // * They should both be called without holding the Heap_lock.
441 //
442 // * All allocation requests for new TLABs should go to
443 // allocate_new_tlab().
444 //
445 // * All non-TLAB allocation requests should go to mem_allocate().
446 //
447 // * If either call cannot satisfy the allocation request using the
448 // current allocating region, they will try to get a new one. If
449 // this fails, they will attempt to do an evacuation pause and
450 // retry the allocation.
451 //
452 // * If all allocation attempts fail, even after trying to schedule
453 // an evacuation pause, allocate_new_tlab() will return NULL,
454 // whereas mem_allocate() will attempt a heap expansion and/or
455 // schedule a Full GC.
456 //
457 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
458 // should never be called with word_size being humongous. All
459 // humongous allocation requests should go to mem_allocate() which
460 // will satisfy them with a special path.
461
462 virtual HeapWord* allocate_new_tlab(size_t word_size);
463
464 virtual HeapWord* mem_allocate(size_t word_size,
465 bool* gc_overhead_limit_was_exceeded);
466
467 // The following three methods take a gc_count_before_ret
468 // parameter which is used to return the GC count if the method
469 // returns NULL. Given that we are required to read the GC count
470 // while holding the Heap_lock, and these paths will take the
471 // Heap_lock at some point, it's easier to get them to read the GC
472 // count while holding the Heap_lock before they return NULL instead
473 // of the caller (namely: mem_allocate()) having to also take the
474 // Heap_lock just to read the GC count.
475
476 // First-level mutator allocation attempt: try to allocate out of
477 // the mutator alloc region without taking the Heap_lock. This
478 // should only be used for non-humongous allocations.
479 inline HeapWord* attempt_allocation(size_t word_size,
480 uint* gc_count_before_ret,
481 uint* gclocker_retry_count_ret);
482
483 // Second-level mutator allocation attempt: take the Heap_lock and
484 // retry the allocation attempt, potentially scheduling a GC
485 // pause. This should only be used for non-humongous allocations.
486 HeapWord* attempt_allocation_slow(size_t word_size,
487 AllocationContext_t context,
488 uint* gc_count_before_ret,
489 uint* gclocker_retry_count_ret);
490
491 // Takes the Heap_lock and attempts a humongous allocation. It can
492 // potentially schedule a GC pause.
493 HeapWord* attempt_allocation_humongous(size_t word_size,
494 uint* gc_count_before_ret,
495 uint* gclocker_retry_count_ret);
496
497 // Allocation attempt that should be called during safepoints (e.g.,
498 // at the end of a successful GC). expect_null_mutator_alloc_region
499 // specifies whether the mutator alloc region is expected to be NULL
500 // or not.
501 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
502 AllocationContext_t context,
503 bool expect_null_mutator_alloc_region);
504
505 public:
506 // It dirties the cards that cover the block so that so that the post
507 // write barrier never queues anything when updating objects on this
508 // block. It is assumed (and in fact we assert) that the block
509 // belongs to a young region.
510 inline void dirty_young_block(HeapWord* start, size_t word_size);
511
512 // These methods are the "callbacks" from the G1AllocRegion class.
513
514 // For mutator alloc regions.
515 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
516 void retire_mutator_alloc_region(HeapRegion* alloc_region,
517 size_t allocated_bytes);
518
519 // For GC alloc regions.
520 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
521 InCSetState dest);
522 void retire_gc_alloc_region(HeapRegion* alloc_region,
523 size_t allocated_bytes, InCSetState dest);
524 private:
525 // - if explicit_gc is true, the GC is for a System.gc() or a heap
526 // inspection request and should collect the entire heap
527 // - if clear_all_soft_refs is true, all soft references should be
528 // cleared during the GC
529 // - if explicit_gc is false, word_size describes the allocation that
530 // the GC should attempt (at least) to satisfy
531 // - it returns false if it is unable to do the collection due to the
532 // GC locker being active, true otherwise
533 bool do_collection(bool explicit_gc,
534 bool clear_all_soft_refs,
535 size_t word_size);
536
537 // Callback from VM_G1CollectFull operation.
538 // Perform a full collection.
539 virtual void do_full_collection(bool clear_all_soft_refs);
540
541 // Resize the heap if necessary after a full collection. If this is
542 // after a collect-for allocation, "word_size" is the allocation size,
543 // and will be considered part of the used portion of the heap.
544 void resize_if_necessary_after_full_collection(size_t word_size);
545
546 // Callback from VM_G1CollectForAllocation operation.
547 // This function does everything necessary/possible to satisfy a
548 // failed allocation request (including collection, expansion, etc.)
549 HeapWord* satisfy_failed_allocation(size_t word_size,
550 AllocationContext_t context,
551 bool* succeeded);
552
553 // Attempting to expand the heap sufficiently
554 // to support an allocation of the given "word_size". If
555 // successful, perform the allocation and return the address of the
556 // allocated block, or else "NULL".
557 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
558
559 // Process any reference objects discovered during
560 // an incremental evacuation pause.
561 void process_discovered_references(G1ParScanThreadState** pss, uint no_of_gc_workers);
562
563 // Enqueue any remaining discovered references
564 // after processing.
565 void enqueue_discovered_references(uint no_of_gc_workers);
566
567 public:
568
569 G1Allocator* allocator() {
570 return _allocator;
571 }
572
573 G1MonitoringSupport* g1mm() {
574 assert(_g1mm != NULL, "should have been initialized");
575 return _g1mm;
576 }
577
578 // Expand the garbage-first heap by at least the given size (in bytes!).
579 // Returns true if the heap was expanded by the requested amount;
580 // false otherwise.
581 // (Rounds up to a HeapRegion boundary.)
582 bool expand(size_t expand_bytes);
583
584 inline AllocationContextStats& allocation_context_stats();
585
586 // Do anything common to GC's.
587 virtual void gc_prologue(bool full);
588 virtual void gc_epilogue(bool full);
589
590 inline void set_humongous_is_live(oop obj);
591
592 bool humongous_is_live(uint region) {
593 return _humongous_is_live.is_live(region);
594 }
595
596 // Returns whether the given region (which must be a humongous (start) region)
597 // is to be considered conservatively live regardless of any other conditions.
598 bool humongous_region_is_always_live(uint index);
599 // Returns whether the given region (which must be a humongous (start) region)
600 // is considered a candidate for eager reclamation.
601 bool humongous_region_is_candidate(uint index);
602 // Register the given region to be part of the collection set.
603 inline void register_humongous_region_with_in_cset_fast_test(uint index);
604 // Register regions with humongous objects (actually on the start region) in
605 // the in_cset_fast_test table.
606 void register_humongous_regions_with_in_cset_fast_test();
607 // We register a region with the fast "in collection set" test. We
608 // simply set to true the array slot corresponding to this region.
609 void register_young_region_with_in_cset_fast_test(HeapRegion* r) {
610 _in_cset_fast_test.set_in_young(r->hrm_index());
611 }
612 void register_old_region_with_in_cset_fast_test(HeapRegion* r) {
613 _in_cset_fast_test.set_in_old(r->hrm_index());
614 }
615
616 // This is a fast test on whether a reference points into the
617 // collection set or not. Assume that the reference
618 // points into the heap.
619 inline bool in_cset_fast_test(oop obj);
620
621 void clear_cset_fast_test() {
622 _in_cset_fast_test.clear();
623 }
624
625 // This is called at the start of either a concurrent cycle or a Full
626 // GC to update the number of old marking cycles started.
627 void increment_old_marking_cycles_started();
628
629 // This is called at the end of either a concurrent cycle or a Full
630 // GC to update the number of old marking cycles completed. Those two
631 // can happen in a nested fashion, i.e., we start a concurrent
632 // cycle, a Full GC happens half-way through it which ends first,
633 // and then the cycle notices that a Full GC happened and ends
634 // too. The concurrent parameter is a boolean to help us do a bit
635 // tighter consistency checking in the method. If concurrent is
636 // false, the caller is the inner caller in the nesting (i.e., the
637 // Full GC). If concurrent is true, the caller is the outer caller
638 // in this nesting (i.e., the concurrent cycle). Further nesting is
639 // not currently supported. The end of this call also notifies
640 // the FullGCCount_lock in case a Java thread is waiting for a full
641 // GC to happen (e.g., it called System.gc() with
642 // +ExplicitGCInvokesConcurrent).
643 void increment_old_marking_cycles_completed(bool concurrent);
644
645 uint old_marking_cycles_completed() {
646 return _old_marking_cycles_completed;
647 }
648
649 void register_concurrent_cycle_start(const Ticks& start_time);
650 void register_concurrent_cycle_end();
651 void trace_heap_after_concurrent_cycle();
652
653 G1YCType yc_type();
654
655 G1HRPrinter* hr_printer() { return &_hr_printer; }
656
657 // Allocates a new heap region instance.
658 virtual HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
659
660 // Frees a non-humongous region by initializing its contents and
661 // adding it to the free list that's passed as a parameter (this is
662 // usually a local list which will be appended to the master free
663 // list later). The used bytes of freed regions are accumulated in
664 // pre_used. If par is true, the region's RSet will not be freed
665 // up. The assumption is that this will be done later.
666 // The locked parameter indicates if the caller has already taken
667 // care of proper synchronization. This may allow some optimizations.
668 void free_region(HeapRegion* hr,
669 FreeRegionList* free_list,
670 bool par,
671 bool locked = false);
672
673 // Frees a humongous region by collapsing it into individual regions
674 // and calling free_region() for each of them. The freed regions
675 // will be added to the free list that's passed as a parameter (this
676 // is usually a local list which will be appended to the master free
677 // list later). The used bytes of freed regions are accumulated in
678 // pre_used. If par is true, the region's RSet will not be freed
679 // up. The assumption is that this will be done later.
680 void free_humongous_region(HeapRegion* hr,
681 FreeRegionList* free_list,
682 bool par);
683 protected:
684
685 // Shrink the garbage-first heap by at most the given size (in bytes!).
686 // (Rounds down to a HeapRegion boundary.)
687 virtual void shrink(size_t expand_bytes);
688 void shrink_helper(size_t expand_bytes);
689
690 #if TASKQUEUE_STATS
691 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
692 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
693 void reset_taskqueue_stats();
694 #endif // TASKQUEUE_STATS
695
696 // Schedule the VM operation that will do an evacuation pause to
697 // satisfy an allocation request of word_size. *succeeded will
698 // return whether the VM operation was successful (it did do an
699 // evacuation pause) or not (another thread beat us to it or the GC
700 // locker was active). Given that we should not be holding the
701 // Heap_lock when we enter this method, we will pass the
702 // gc_count_before (i.e., total_collections()) as a parameter since
703 // it has to be read while holding the Heap_lock. Currently, both
704 // methods that call do_collection_pause() release the Heap_lock
705 // before the call, so it's easy to read gc_count_before just before.
706 HeapWord* do_collection_pause(size_t word_size,
707 uint gc_count_before,
708 bool* succeeded,
709 GCCause::Cause gc_cause);
710
711 // The guts of the incremental collection pause, executed by the vm
712 // thread. It returns false if it is unable to do the collection due
713 // to the GC locker being active, true otherwise
714 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
715
716 // Actually do the work of evacuating the collection set.
717 void evacuate_collection_set(EvacuationInfo& evacuation_info);
718
719 // Print the header for the per-thread termination statistics.
720 static void print_termination_stats_hdr(outputStream* const st);
721 // Print actual per-thread termination statistics.
722 void print_termination_stats(outputStream* const st,
723 uint worker_id,
724 double elapsed_ms,
725 double strong_roots_ms,
726 double term_ms,
727 size_t term_attempts,
728 size_t alloc_buffer_waste,
729 size_t undo_waste) const;
730 // Update object copying statistics.
731 void record_obj_copy_mem_stats();
732 void record_obj_copy_mem_stats(InCSetState which);
733
734 // The g1 remembered set of the heap.
735 G1RemSet* _g1_rem_set;
736
737 // A set of cards that cover the objects for which the Rsets should be updated
738 // concurrently after the collection.
739 DirtyCardQueueSet _dirty_card_queue_set;
740
741 // The closure used to refine a single card.
742 RefineCardTableEntryClosure* _refine_cte_cl;
743
744 // A DirtyCardQueueSet that is used to hold cards that contain
745 // references into the current collection set. This is used to
746 // update the remembered sets of the regions in the collection
747 // set in the event of an evacuation failure.
748 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
749
750 // After a collection pause, make the regions in the CS into free
751 // regions.
752 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info);
753
754 // Abandon the current collection set without recording policy
755 // statistics or updating free lists.
756 void abandon_collection_set(HeapRegion* cs_head);
757
758 // Applies "scan_non_heap_roots" to roots outside the heap,
759 // "scan_rs" to roots inside the heap (having done "set_region" to
760 // indicate the region in which the root resides),
761 // and does "scan_metadata" If "scan_rs" is
762 // NULL, then this step is skipped. The "worker_i"
763 // param is for use with parallel roots processing, and should be
764 // the "i" of the calling parallel worker thread's work(i) function.
765 // In the sequential case this param will be ignored.
766 void g1_process_roots(OopClosure* scan_non_heap_roots,
767 OopClosure* scan_non_heap_weak_roots,
768 G1ParPushHeapRSClosure* scan_rs,
769 CLDClosure* scan_strong_clds,
770 CLDClosure* scan_weak_clds,
771 CodeBlobClosure* scan_strong_code,
772 uint worker_i);
773
774 // The concurrent marker (and the thread it runs in.)
775 ConcurrentMark* _cm;
776 ConcurrentMarkThread* _cmThread;
777 bool _mark_in_progress;
778
779 // The concurrent refiner.
780 ConcurrentG1Refine* _cg1r;
781
782 // The parallel task queues
783 RefToScanQueueSet *_task_queues;
784
785 // True iff a evacuation has failed in the current collection.
786 bool _evacuation_failed;
787
788 EvacuationFailedInfo* _evacuation_failed_info_array;
789
790 // Failed evacuations cause some logical from-space objects to have
791 // forwarding pointers to themselves. Reset them.
792 void remove_self_forwarding_pointers();
793
794 // Together, these store an object with a preserved mark, and its mark value.
795 Stack<oop, mtGC> _objs_with_preserved_marks;
796 Stack<markOop, mtGC> _preserved_marks_of_objs;
797
798 // Preserve the mark of "obj", if necessary, in preparation for its mark
799 // word being overwritten with a self-forwarding-pointer.
800 void preserve_mark_if_necessary(oop obj, markOop m);
801
802 // The stack of evac-failure objects left to be scanned.
803 GrowableArray<oop>* _evac_failure_scan_stack;
804 // The closure to apply to evac-failure objects.
805
806 OopsInHeapRegionClosure* _evac_failure_closure;
807 // Set the field above.
808 void
809 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
810 _evac_failure_closure = evac_failure_closure;
811 }
812
813 // Push "obj" on the scan stack.
814 void push_on_evac_failure_scan_stack(oop obj);
815 // Process scan stack entries until the stack is empty.
816 void drain_evac_failure_scan_stack();
817 // True iff an invocation of "drain_scan_stack" is in progress; to
818 // prevent unnecessary recursion.
819 bool _drain_in_progress;
820
821 // Do any necessary initialization for evacuation-failure handling.
822 // "cl" is the closure that will be used to process evac-failure
823 // objects.
824 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
825 // Do any necessary cleanup for evacuation-failure handling data
826 // structures.
827 void finalize_for_evac_failure();
828
829 // An attempt to evacuate "obj" has failed; take necessary steps.
830 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj);
831 void handle_evacuation_failure_common(oop obj, markOop m);
832
833 #ifndef PRODUCT
834 // Support for forcing evacuation failures. Analogous to
835 // PromotionFailureALot for the other collectors.
836
837 // Records whether G1EvacuationFailureALot should be in effect
838 // for the current GC
839 bool _evacuation_failure_alot_for_current_gc;
840
841 // Used to record the GC number for interval checking when
842 // determining whether G1EvaucationFailureALot is in effect
843 // for the current GC.
844 size_t _evacuation_failure_alot_gc_number;
845
846 // Count of the number of evacuations between failures.
847 volatile size_t _evacuation_failure_alot_count;
848
849 // Set whether G1EvacuationFailureALot should be in effect
850 // for the current GC (based upon the type of GC and which
851 // command line flags are set);
852 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
853 bool during_initial_mark,
854 bool during_marking);
855
856 inline void set_evacuation_failure_alot_for_current_gc();
857
858 // Return true if it's time to cause an evacuation failure.
859 inline bool evacuation_should_fail();
860
861 // Reset the G1EvacuationFailureALot counters. Should be called at
862 // the end of an evacuation pause in which an evacuation failure occurred.
863 inline void reset_evacuation_should_fail();
864 #endif // !PRODUCT
865
866 // ("Weak") Reference processing support.
867 //
868 // G1 has 2 instances of the reference processor class. One
869 // (_ref_processor_cm) handles reference object discovery
870 // and subsequent processing during concurrent marking cycles.
871 //
872 // The other (_ref_processor_stw) handles reference object
873 // discovery and processing during full GCs and incremental
874 // evacuation pauses.
875 //
876 // During an incremental pause, reference discovery will be
877 // temporarily disabled for _ref_processor_cm and will be
878 // enabled for _ref_processor_stw. At the end of the evacuation
879 // pause references discovered by _ref_processor_stw will be
880 // processed and discovery will be disabled. The previous
881 // setting for reference object discovery for _ref_processor_cm
882 // will be re-instated.
883 //
884 // At the start of marking:
885 // * Discovery by the CM ref processor is verified to be inactive
886 // and it's discovered lists are empty.
887 // * Discovery by the CM ref processor is then enabled.
888 //
889 // At the end of marking:
890 // * Any references on the CM ref processor's discovered
891 // lists are processed (possibly MT).
892 //
893 // At the start of full GC we:
894 // * Disable discovery by the CM ref processor and
895 // empty CM ref processor's discovered lists
896 // (without processing any entries).
897 // * Verify that the STW ref processor is inactive and it's
898 // discovered lists are empty.
899 // * Temporarily set STW ref processor discovery as single threaded.
900 // * Temporarily clear the STW ref processor's _is_alive_non_header
901 // field.
902 // * Finally enable discovery by the STW ref processor.
903 //
904 // The STW ref processor is used to record any discovered
905 // references during the full GC.
906 //
907 // At the end of a full GC we:
908 // * Enqueue any reference objects discovered by the STW ref processor
909 // that have non-live referents. This has the side-effect of
910 // making the STW ref processor inactive by disabling discovery.
911 // * Verify that the CM ref processor is still inactive
912 // and no references have been placed on it's discovered
913 // lists (also checked as a precondition during initial marking).
914
915 // The (stw) reference processor...
916 ReferenceProcessor* _ref_processor_stw;
917
918 STWGCTimer* _gc_timer_stw;
919 ConcurrentGCTimer* _gc_timer_cm;
920
921 G1OldTracer* _gc_tracer_cm;
922 G1NewTracer* _gc_tracer_stw;
923
924 // During reference object discovery, the _is_alive_non_header
925 // closure (if non-null) is applied to the referent object to
926 // determine whether the referent is live. If so then the
927 // reference object does not need to be 'discovered' and can
928 // be treated as a regular oop. This has the benefit of reducing
929 // the number of 'discovered' reference objects that need to
930 // be processed.
931 //
932 // Instance of the is_alive closure for embedding into the
933 // STW reference processor as the _is_alive_non_header field.
934 // Supplying a value for the _is_alive_non_header field is
935 // optional but doing so prevents unnecessary additions to
936 // the discovered lists during reference discovery.
937 G1STWIsAliveClosure _is_alive_closure_stw;
938
939 // The (concurrent marking) reference processor...
940 ReferenceProcessor* _ref_processor_cm;
941
942 // Instance of the concurrent mark is_alive closure for embedding
943 // into the Concurrent Marking reference processor as the
944 // _is_alive_non_header field. Supplying a value for the
945 // _is_alive_non_header field is optional but doing so prevents
946 // unnecessary additions to the discovered lists during reference
947 // discovery.
948 G1CMIsAliveClosure _is_alive_closure_cm;
949
950 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
951 HeapRegion** _worker_cset_start_region;
952
953 // Time stamp to validate the regions recorded in the cache
954 // used by G1CollectedHeap::start_cset_region_for_worker().
955 // The heap region entry for a given worker is valid iff
956 // the associated time stamp value matches the current value
957 // of G1CollectedHeap::_gc_time_stamp.
958 uint* _worker_cset_start_region_time_stamp;
959
960 enum G1H_process_roots_tasks {
961 G1H_PS_filter_satb_buffers,
962 G1H_PS_refProcessor_oops_do,
963 // Leave this one last.
964 G1H_PS_NumElements
965 };
966
967 SubTasksDone* _process_strong_tasks;
968
969 volatile bool _free_regions_coming;
970
971 public:
972
973 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
974
975 void set_refine_cte_cl_concurrency(bool concurrent);
976
977 RefToScanQueue *task_queue(int i) const;
978
979 // A set of cards where updates happened during the GC
980 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
981
982 // A DirtyCardQueueSet that is used to hold cards that contain
983 // references into the current collection set. This is used to
984 // update the remembered sets of the regions in the collection
985 // set in the event of an evacuation failure.
986 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
987 { return _into_cset_dirty_card_queue_set; }
988
989 // Create a G1CollectedHeap with the specified policy.
990 // Must call the initialize method afterwards.
991 // May not return if something goes wrong.
992 G1CollectedHeap(G1CollectorPolicy* policy);
993
994 // Initialize the G1CollectedHeap to have the initial and
995 // maximum sizes and remembered and barrier sets
996 // specified by the policy object.
997 jint initialize();
998
999 virtual void stop();
1000
1001 // Return the (conservative) maximum heap alignment for any G1 heap
1002 static size_t conservative_max_heap_alignment();
1003
1004 // Initialize weak reference processing.
1005 virtual void ref_processing_init();
1006
1007 void set_par_threads(uint t) {
1008 SharedHeap::set_par_threads(t);
1009 // Done in SharedHeap but oddly there are
1010 // two _process_strong_tasks's in a G1CollectedHeap
1011 // so do it here too.
1012 _process_strong_tasks->set_n_threads(t);
1013 }
1014
1015 // Set _n_par_threads according to a policy TBD.
1016 void set_par_threads();
1017
1018 void set_n_termination(int t) {
1019 _process_strong_tasks->set_n_threads(t);
1020 }
1021
1022 virtual CollectedHeap::Name kind() const {
1023 return CollectedHeap::G1CollectedHeap;
1024 }
1025
1026 // The current policy object for the collector.
1027 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1028
1029 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); }
1030
1031 // Adaptive size policy. No such thing for g1.
1032 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1033
1034 // The rem set and barrier set.
1035 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1036
1037 unsigned get_gc_time_stamp() {
1038 return _gc_time_stamp;
1039 }
1040
1041 inline void reset_gc_time_stamp();
1042
1043 void check_gc_time_stamps() PRODUCT_RETURN;
1044
1045 inline void increment_gc_time_stamp();
1046
1047 // Reset the given region's GC timestamp. If it's starts humongous,
1048 // also reset the GC timestamp of its corresponding
1049 // continues humongous regions too.
1050 void reset_gc_time_stamps(HeapRegion* hr);
1051
1052 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1053 DirtyCardQueue* into_cset_dcq,
1054 bool concurrent, uint worker_i);
1055
1056 // The shared block offset table array.
1057 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1058
1059 // Reference Processing accessors
1060
1061 // The STW reference processor....
1062 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1063
1064 // The Concurrent Marking reference processor...
1065 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1066
1067 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1068 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1069
1070 virtual size_t capacity() const;
1071 virtual size_t used() const;
1072 // This should be called when we're not holding the heap lock. The
1073 // result might be a bit inaccurate.
1074 size_t used_unlocked() const;
1075 size_t recalculate_used() const;
1076
1077 void increase_used(size_t bytes) { _summary_bytes_used += bytes; }
1078 void set_used(size_t bytes) { _summary_bytes_used = bytes; }
1079
1080 void decrease_used(size_t bytes) {
1081 assert(_summary_bytes_used >= bytes,
1082 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
1083 _summary_bytes_used, bytes));
1084 _summary_bytes_used -= bytes;
1085 }
1086
1087 // These virtual functions do the actual allocation.
1088 // Some heaps may offer a contiguous region for shared non-blocking
1089 // allocation, via inlined code (by exporting the address of the top and
1090 // end fields defining the extent of the contiguous allocation region.)
1091 // But G1CollectedHeap doesn't yet support this.
1092
1093 virtual bool is_maximal_no_gc() const {
1094 return _hrm.available() == 0;
1095 }
1096
1097 // The current number of regions in the heap.
1098 uint num_regions() const { return _hrm.length(); }
1099
1100 // The max number of regions in the heap.
1101 uint max_regions() const { return _hrm.max_length(); }
1102
1103 // The number of regions that are completely free.
1104 uint num_free_regions() const { return _hrm.num_free_regions(); }
1105
1106 // The number of regions that are not completely free.
1107 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1108
1109 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1110 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1111 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1112 void verify_dirty_young_regions() PRODUCT_RETURN;
1113
1114 #ifndef PRODUCT
1115 // Make sure that the given bitmap has no marked objects in the
1116 // range [from,limit). If it does, print an error message and return
1117 // false. Otherwise, just return true. bitmap_name should be "prev"
1118 // or "next".
1119 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1120 HeapWord* from, HeapWord* limit);
1121
1122 // Verify that the prev / next bitmap range [tams,end) for the given
1123 // region has no marks. Return true if all is well, false if errors
1124 // are detected.
1125 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1126 #endif // PRODUCT
1127
1128 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1129 // the given region do not have any spurious marks. If errors are
1130 // detected, print appropriate error messages and crash.
1131 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1132
1133 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1134 // have any spurious marks. If errors are detected, print
1135 // appropriate error messages and crash.
1136 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1137
1138 // Do sanity check on the contents of the in-cset fast test table.
1139 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1140
1141 // verify_region_sets() performs verification over the region
1142 // lists. It will be compiled in the product code to be used when
1143 // necessary (i.e., during heap verification).
1144 void verify_region_sets();
1145
1146 // verify_region_sets_optional() is planted in the code for
1147 // list verification in non-product builds (and it can be enabled in
1148 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1149 #if HEAP_REGION_SET_FORCE_VERIFY
1150 void verify_region_sets_optional() {
1151 verify_region_sets();
1152 }
1153 #else // HEAP_REGION_SET_FORCE_VERIFY
1154 void verify_region_sets_optional() { }
1155 #endif // HEAP_REGION_SET_FORCE_VERIFY
1156
1157 #ifdef ASSERT
1158 bool is_on_master_free_list(HeapRegion* hr) {
1159 return _hrm.is_free(hr);
1160 }
1161 #endif // ASSERT
1162
1163 // Wrapper for the region list operations that can be called from
1164 // methods outside this class.
1165
1166 void secondary_free_list_add(FreeRegionList* list) {
1167 _secondary_free_list.add_ordered(list);
1168 }
1169
1170 void append_secondary_free_list() {
1171 _hrm.insert_list_into_free_list(&_secondary_free_list);
1172 }
1173
1174 void append_secondary_free_list_if_not_empty_with_lock() {
1175 // If the secondary free list looks empty there's no reason to
1176 // take the lock and then try to append it.
1177 if (!_secondary_free_list.is_empty()) {
1178 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1179 append_secondary_free_list();
1180 }
1181 }
1182
1183 inline void old_set_remove(HeapRegion* hr);
1184
1185 size_t non_young_capacity_bytes() {
1186 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1187 }
1188
1189 void set_free_regions_coming();
1190 void reset_free_regions_coming();
1191 bool free_regions_coming() { return _free_regions_coming; }
1192 void wait_while_free_regions_coming();
1193
1194 // Determine whether the given region is one that we are using as an
1195 // old GC alloc region.
1196 bool is_old_gc_alloc_region(HeapRegion* hr) {
1197 return _allocator->is_retained_old_region(hr);
1198 }
1199
1200 // Perform a collection of the heap; intended for use in implementing
1201 // "System.gc". This probably implies as full a collection as the
1202 // "CollectedHeap" supports.
1203 virtual void collect(GCCause::Cause cause);
1204
1205 // The same as above but assume that the caller holds the Heap_lock.
1206 void collect_locked(GCCause::Cause cause);
1207
1208 virtual bool copy_allocation_context_stats(const jint* contexts,
1209 jlong* totals,
1210 jbyte* accuracy,
1211 jint len);
1212
1213 // True iff an evacuation has failed in the most-recent collection.
1214 bool evacuation_failed() { return _evacuation_failed; }
1215
1216 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1217 void prepend_to_freelist(FreeRegionList* list);
1218 void decrement_summary_bytes(size_t bytes);
1219
1220 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1221 virtual bool is_in(const void* p) const;
1222 #ifdef ASSERT
1223 // Returns whether p is in one of the available areas of the heap. Slow but
1224 // extensive version.
1225 bool is_in_exact(const void* p) const;
1226 #endif
1227
1228 // Return "TRUE" iff the given object address is within the collection
1229 // set. Slow implementation.
1230 inline bool obj_in_cs(oop obj);
1231
1232 inline bool is_in_cset(oop obj);
1233
1234 inline bool is_in_cset_or_humongous(const oop obj);
1235
1236 private:
1237 // This array is used for a quick test on whether a reference points into
1238 // the collection set or not. Each of the array's elements denotes whether the
1239 // corresponding region is in the collection set or not.
1240 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1241
1242 public:
1243
1244 inline InCSetState in_cset_state(const oop obj);
1245
1246 // Return "TRUE" iff the given object address is in the reserved
1247 // region of g1.
1248 bool is_in_g1_reserved(const void* p) const {
1249 return _hrm.reserved().contains(p);
1250 }
1251
1252 // Returns a MemRegion that corresponds to the space that has been
1253 // reserved for the heap
1254 MemRegion g1_reserved() const {
1255 return _hrm.reserved();
1256 }
1257
1258 virtual bool is_in_closed_subset(const void* p) const;
1259
1260 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1261 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1262 }
1263
1264 // This resets the card table to all zeros. It is used after
1265 // a collection pause which used the card table to claim cards.
1266 void cleanUpCardTable();
1267
1268 // Iteration functions.
1269
1270 // Iterate over all the ref-containing fields of all objects, calling
1271 // "cl.do_oop" on each.
1272 virtual void oop_iterate(ExtendedOopClosure* cl);
1273
1274 // Iterate over all objects, calling "cl.do_object" on each.
1275 virtual void object_iterate(ObjectClosure* cl);
1276
1277 virtual void safe_object_iterate(ObjectClosure* cl) {
1278 object_iterate(cl);
1279 }
1280
1281 // Iterate over all spaces in use in the heap, in ascending address order.
1282 virtual void space_iterate(SpaceClosure* cl);
1283
1284 // Iterate over heap regions, in address order, terminating the
1285 // iteration early if the "doHeapRegion" method returns "true".
1286 void heap_region_iterate(HeapRegionClosure* blk) const;
1287
1288 // Return the region with the given index. It assumes the index is valid.
1289 inline HeapRegion* region_at(uint index) const;
1290
1291 // Calculate the region index of the given address. Given address must be
1292 // within the heap.
1293 inline uint addr_to_region(HeapWord* addr) const;
1294
1295 inline HeapWord* bottom_addr_for_region(uint index) const;
1296
1297 // Iterate over the heap regions in parallel. Assumes that this will be called
1298 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1299 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1300 // to each of the regions, by attempting to claim the region using the
1301 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1302 // region. The concurrent argument should be set to true if iteration is
1303 // performed concurrently, during which no assumptions are made for consistent
1304 // attributes of the heap regions (as they might be modified while iterating).
1305 void heap_region_par_iterate(HeapRegionClosure* cl,
1306 uint worker_id,
1307 HeapRegionClaimer* hrclaimer,
1308 bool concurrent = false) const;
1309
1310 // Clear the cached cset start regions and (more importantly)
1311 // the time stamps. Called when we reset the GC time stamp.
1312 void clear_cset_start_regions();
1313
1314 // Given the id of a worker, obtain or calculate a suitable
1315 // starting region for iterating over the current collection set.
1316 HeapRegion* start_cset_region_for_worker(uint worker_i);
1317
1318 // Iterate over the regions (if any) in the current collection set.
1319 void collection_set_iterate(HeapRegionClosure* blk);
1320
1321 // As above but starting from region r
1322 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1323
1324 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1325
1326 // A CollectedHeap will contain some number of spaces. This finds the
1327 // space containing a given address, or else returns NULL.
1328 virtual Space* space_containing(const void* addr) const;
1329
1330 // Returns the HeapRegion that contains addr. addr must not be NULL.
1331 template <class T>
1332 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1333
1334 // Returns the HeapRegion that contains addr. addr must not be NULL.
1335 // If addr is within a humongous continues region, it returns its humongous start region.
1336 template <class T>
1337 inline HeapRegion* heap_region_containing(const T addr) const;
1338
1339 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1340 // each address in the (reserved) heap is a member of exactly
1341 // one block. The defining characteristic of a block is that it is
1342 // possible to find its size, and thus to progress forward to the next
1343 // block. (Blocks may be of different sizes.) Thus, blocks may
1344 // represent Java objects, or they might be free blocks in a
1345 // free-list-based heap (or subheap), as long as the two kinds are
1346 // distinguishable and the size of each is determinable.
1347
1348 // Returns the address of the start of the "block" that contains the
1349 // address "addr". We say "blocks" instead of "object" since some heaps
1350 // may not pack objects densely; a chunk may either be an object or a
1351 // non-object.
1352 virtual HeapWord* block_start(const void* addr) const;
1353
1354 // Requires "addr" to be the start of a chunk, and returns its size.
1355 // "addr + size" is required to be the start of a new chunk, or the end
1356 // of the active area of the heap.
1357 virtual size_t block_size(const HeapWord* addr) const;
1358
1359 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1360 // the block is an object.
1361 virtual bool block_is_obj(const HeapWord* addr) const;
1362
1363 // Does this heap support heap inspection? (+PrintClassHistogram)
1364 virtual bool supports_heap_inspection() const { return true; }
1365
1366 // Section on thread-local allocation buffers (TLABs)
1367 // See CollectedHeap for semantics.
1368
1369 bool supports_tlab_allocation() const;
1370 size_t tlab_capacity(Thread* ignored) const;
1371 size_t tlab_used(Thread* ignored) const;
1372 size_t max_tlab_size() const;
1373 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1374
1375 // Can a compiler initialize a new object without store barriers?
1376 // This permission only extends from the creation of a new object
1377 // via a TLAB up to the first subsequent safepoint. If such permission
1378 // is granted for this heap type, the compiler promises to call
1379 // defer_store_barrier() below on any slow path allocation of
1380 // a new object for which such initializing store barriers will
1381 // have been elided. G1, like CMS, allows this, but should be
1382 // ready to provide a compensating write barrier as necessary
1383 // if that storage came out of a non-young region. The efficiency
1384 // of this implementation depends crucially on being able to
1385 // answer very efficiently in constant time whether a piece of
1386 // storage in the heap comes from a young region or not.
1387 // See ReduceInitialCardMarks.
1388 virtual bool can_elide_tlab_store_barriers() const {
1389 return true;
1390 }
1391
1392 virtual bool card_mark_must_follow_store() const {
1393 return true;
1394 }
1395
1396 inline bool is_in_young(const oop obj);
1397
1398 #ifdef ASSERT
1399 virtual bool is_in_partial_collection(const void* p);
1400 #endif
1401
1402 virtual bool is_scavengable(const void* addr);
1403
1404 // We don't need barriers for initializing stores to objects
1405 // in the young gen: for the SATB pre-barrier, there is no
1406 // pre-value that needs to be remembered; for the remembered-set
1407 // update logging post-barrier, we don't maintain remembered set
1408 // information for young gen objects.
1409 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1410
1411 // Returns "true" iff the given word_size is "very large".
1412 static bool is_humongous(size_t word_size) {
1413 // Note this has to be strictly greater-than as the TLABs
1414 // are capped at the humongous threshold and we want to
1415 // ensure that we don't try to allocate a TLAB as
1416 // humongous and that we don't allocate a humongous
1417 // object in a TLAB.
1418 return word_size > _humongous_object_threshold_in_words;
1419 }
1420
1421 static size_t humongous_object_threshold_in_words() { return _humongous_object_threshold_in_words; }
1422
1423 // Update mod union table with the set of dirty cards.
1424 void updateModUnion();
1425
1426 // Set the mod union bits corresponding to the given memRegion. Note
1427 // that this is always a safe operation, since it doesn't clear any
1428 // bits.
1429 void markModUnionRange(MemRegion mr);
1430
1431 // Records the fact that a marking phase is no longer in progress.
1432 void set_marking_complete() {
1433 _mark_in_progress = false;
1434 }
1435 void set_marking_started() {
1436 _mark_in_progress = true;
1437 }
1438 bool mark_in_progress() {
1439 return _mark_in_progress;
1440 }
1441
1442 // Print the maximum heap capacity.
1443 virtual size_t max_capacity() const;
1444
1445 virtual jlong millis_since_last_gc();
1446
1447
1448 // Convenience function to be used in situations where the heap type can be
1449 // asserted to be this type.
1450 static G1CollectedHeap* heap();
1451
1452 void set_region_short_lived_locked(HeapRegion* hr);
1453 // add appropriate methods for any other surv rate groups
1454
1455 YoungList* young_list() const { return _young_list; }
1456
1457 // debugging
1458 bool check_young_list_well_formed() {
1459 return _young_list->check_list_well_formed();
1460 }
1461
1462 bool check_young_list_empty(bool check_heap,
1463 bool check_sample = true);
1464
1465 // *** Stuff related to concurrent marking. It's not clear to me that so
1466 // many of these need to be public.
1467
1468 // The functions below are helper functions that a subclass of
1469 // "CollectedHeap" can use in the implementation of its virtual
1470 // functions.
1471 // This performs a concurrent marking of the live objects in a
1472 // bitmap off to the side.
1473 void doConcurrentMark();
1474
1475 bool isMarkedPrev(oop obj) const;
1476 bool isMarkedNext(oop obj) const;
1477
1478 // Determine if an object is dead, given the object and also
1479 // the region to which the object belongs. An object is dead
1480 // iff a) it was not allocated since the last mark and b) it
1481 // is not marked.
1482 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1483 return
1484 !hr->obj_allocated_since_prev_marking(obj) &&
1485 !isMarkedPrev(obj);
1486 }
1487
1488 // This function returns true when an object has been
1489 // around since the previous marking and hasn't yet
1490 // been marked during this marking.
1491 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1492 return
1493 !hr->obj_allocated_since_next_marking(obj) &&
1494 !isMarkedNext(obj);
1495 }
1496
1497 // Determine if an object is dead, given only the object itself.
1498 // This will find the region to which the object belongs and
1499 // then call the region version of the same function.
1500
1501 // Added if it is NULL it isn't dead.
1502
1503 inline bool is_obj_dead(const oop obj) const;
1504
1505 inline bool is_obj_ill(const oop obj) const;
1506
1507 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1508 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1509 bool is_marked(oop obj, VerifyOption vo);
1510 const char* top_at_mark_start_str(VerifyOption vo);
1511
1512 ConcurrentMark* concurrent_mark() const { return _cm; }
1513
1514 // Refinement
1515
1516 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1517
1518 // The dirty cards region list is used to record a subset of regions
1519 // whose cards need clearing. The list if populated during the
1520 // remembered set scanning and drained during the card table
1521 // cleanup. Although the methods are reentrant, population/draining
1522 // phases must not overlap. For synchronization purposes the last
1523 // element on the list points to itself.
1524 HeapRegion* _dirty_cards_region_list;
1525 void push_dirty_cards_region(HeapRegion* hr);
1526 HeapRegion* pop_dirty_cards_region();
1527
1528 // Optimized nmethod scanning support routines
1529
1530 // Register the given nmethod with the G1 heap.
1531 virtual void register_nmethod(nmethod* nm);
1532
1533 // Unregister the given nmethod from the G1 heap.
1534 virtual void unregister_nmethod(nmethod* nm);
1535
1536 // Free up superfluous code root memory.
1537 void purge_code_root_memory();
1538
1539 // Rebuild the strong code root lists for each region
1540 // after a full GC.
1541 void rebuild_strong_code_roots();
1542
1543 // Delete entries for dead interned string and clean up unreferenced symbols
1544 // in symbol table, possibly in parallel.
1545 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1546
1547 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1548 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1549
1550 // Redirty logged cards in the refinement queue.
1551 void redirty_logged_cards();
1552 // Verification
1553
1554 // The following is just to alert the verification code
1555 // that a full collection has occurred and that the
1556 // remembered sets are no longer up to date.
1557 bool _full_collection;
1558 void set_full_collection() { _full_collection = true;}
1559 void clear_full_collection() {_full_collection = false;}
1560 bool full_collection() {return _full_collection;}
1561
1562 // Perform any cleanup actions necessary before allowing a verification.
1563 virtual void prepare_for_verify();
1564
1565 // Perform verification.
1566
1567 // vo == UsePrevMarking -> use "prev" marking information,
1568 // vo == UseNextMarking -> use "next" marking information
1569 // vo == UseMarkWord -> use the mark word in the object header
1570 //
1571 // NOTE: Only the "prev" marking information is guaranteed to be
1572 // consistent most of the time, so most calls to this should use
1573 // vo == UsePrevMarking.
1574 // Currently, there is only one case where this is called with
1575 // vo == UseNextMarking, which is to verify the "next" marking
1576 // information at the end of remark.
1577 // Currently there is only one place where this is called with
1578 // vo == UseMarkWord, which is to verify the marking during a
1579 // full GC.
1580 void verify(bool silent, VerifyOption vo);
1581
1582 // Override; it uses the "prev" marking information
1583 virtual void verify(bool silent);
1584
1585 // The methods below are here for convenience and dispatch the
1586 // appropriate method depending on value of the given VerifyOption
1587 // parameter. The values for that parameter, and their meanings,
1588 // are the same as those above.
1589
1590 bool is_obj_dead_cond(const oop obj,
1591 const HeapRegion* hr,
1592 const VerifyOption vo) const;
1593
1594 bool is_obj_dead_cond(const oop obj,
1595 const VerifyOption vo) const;
1596
1597 // Printing
1598
1599 virtual void print_on(outputStream* st) const;
1600 virtual void print_extended_on(outputStream* st) const;
1601 virtual void print_on_error(outputStream* st) const;
1602
1603 virtual void print_gc_threads_on(outputStream* st) const;
1604 virtual void gc_threads_do(ThreadClosure* tc) const;
1605
1606 // Override
1607 void print_tracing_info() const;
1608
1609 // The following two methods are helpful for debugging RSet issues.
1610 void print_cset_rsets() PRODUCT_RETURN;
1611 void print_all_rsets() PRODUCT_RETURN;
1612
1613 public:
1614 size_t pending_card_num();
1615 size_t cards_scanned();
1616
1617 protected:
1618 size_t _max_heap_capacity;
1619 };
1620
1621 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP