1 /*
2 * Copyright (c) 2001, 2020, 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_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/g1BarrierSet.hpp"
29 #include "gc/g1/g1BiasedArray.hpp"
30 #include "gc/g1/g1CardTable.hpp"
31 #include "gc/g1/g1CollectionSet.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.hpp"
34 #include "gc/g1/g1EdenRegions.hpp"
35 #include "gc/g1/g1EvacFailure.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1EvacuationInfo.hpp"
38 #include "gc/g1/g1GCPhaseTimes.hpp"
39 #include "gc/g1/g1HeapTransition.hpp"
40 #include "gc/g1/g1HeapVerifier.hpp"
41 #include "gc/g1/g1HRPrinter.hpp"
42 #include "gc/g1/g1HeapRegionAttr.hpp"
43 #include "gc/g1/g1MonitoringSupport.hpp"
44 #include "gc/g1/g1NUMA.hpp"
45 #include "gc/g1/g1RedirtyCardsQueue.hpp"
46 #include "gc/g1/g1SurvivorRegions.hpp"
47 #include "gc/g1/g1YCTypes.hpp"
48 #include "gc/g1/heapRegionManager.hpp"
49 #include "gc/g1/heapRegionSet.hpp"
50 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
51 #include "gc/shared/barrierSet.hpp"
52 #include "gc/shared/collectedHeap.hpp"
53 #include "gc/shared/gcHeapSummary.hpp"
54 #include "gc/shared/plab.hpp"
55 #include "gc/shared/preservedMarks.hpp"
56 #include "gc/shared/softRefPolicy.hpp"
57 #include "gc/shared/taskqueue.hpp"
58 #include "memory/memRegion.hpp"
59 #include "utilities/stack.hpp"
60
61 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
62 // It uses the "Garbage First" heap organization and algorithm, which
63 // may combine concurrent marking with parallel, incremental compaction of
64 // heap subsets that will yield large amounts of garbage.
65
66 // Forward declarations
67 class HeapRegion;
68 class GenerationSpec;
69 class G1ParScanThreadState;
70 class G1ParScanThreadStateSet;
71 class G1ParScanThreadState;
72 class MemoryPool;
73 class MemoryManager;
74 class ObjectClosure;
75 class SpaceClosure;
76 class CompactibleSpaceClosure;
77 class Space;
78 class G1CardTableEntryClosure;
79 class G1CollectionSet;
80 class G1Policy;
81 class G1HotCardCache;
82 class G1RemSet;
83 class G1YoungRemSetSamplingThread;
84 class G1ConcurrentMark;
85 class G1ConcurrentMarkThread;
86 class G1ConcurrentRefine;
87 class GenerationCounters;
88 class STWGCTimer;
89 class G1NewTracer;
90 class EvacuationFailedInfo;
91 class nmethod;
92 class WorkGang;
93 class G1Allocator;
94 class G1ArchiveAllocator;
95 class G1FullGCScope;
96 class G1HeapVerifier;
97 class G1HeapSizingPolicy;
98 class G1HeapSummary;
99 class G1EvacSummary;
100
101 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue;
102 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet;
103
104 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
105 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
106
107 // The G1 STW is alive closure.
108 // An instance is embedded into the G1CH and used as the
109 // (optional) _is_alive_non_header closure in the STW
110 // reference processor. It is also extensively used during
111 // reference processing during STW evacuation pauses.
112 class G1STWIsAliveClosure : public BoolObjectClosure {
113 G1CollectedHeap* _g1h;
114 public:
115 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
116 bool do_object_b(oop p);
117 };
118
119 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
120 G1CollectedHeap* _g1h;
121 public:
122 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
123 bool do_object_b(oop p);
124 };
125
126 class G1RegionMappingChangedListener : public G1MappingChangedListener {
127 private:
128 void reset_from_card_cache(uint start_idx, size_t num_regions);
129 public:
130 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
131 };
132
133 class G1CollectedHeap : public CollectedHeap {
134 friend class VM_CollectForMetadataAllocation;
135 friend class VM_G1CollectForAllocation;
136 friend class VM_G1CollectFull;
137 friend class VM_G1TryInitiateConcMark;
138 friend class VMStructs;
139 friend class MutatorAllocRegion;
140 friend class G1FullCollector;
141 friend class G1GCAllocRegion;
142 friend class G1HeapVerifier;
143
144 // Closures used in implementation.
145 friend class G1ParScanThreadState;
146 friend class G1ParScanThreadStateSet;
147 friend class G1EvacuateRegionsTask;
148 friend class G1PLABAllocator;
149
150 // Other related classes.
151 friend class HeapRegionClaimer;
152
153 // Testing classes.
154 friend class G1CheckRegionAttrTableClosure;
155
156 private:
157 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
158
159 WorkGang* _workers;
160 G1CardTable* _card_table;
161
162 SoftRefPolicy _soft_ref_policy;
163
164 static size_t _humongous_object_threshold_in_words;
165
166 // These sets keep track of old, archive and humongous regions respectively.
167 HeapRegionSet _old_set;
168 HeapRegionSet _archive_set;
169 HeapRegionSet _humongous_set;
170
171 void eagerly_reclaim_humongous_regions();
172 // Start a new incremental collection set for the next pause.
173 void start_new_collection_set();
174
175 // The block offset table for the G1 heap.
176 G1BlockOffsetTable* _bot;
177
178 // Tears down the region sets / lists so that they are empty and the
179 // regions on the heap do not belong to a region set / list. The
180 // only exception is the humongous set which we leave unaltered. If
181 // free_list_only is true, it will only tear down the master free
182 // list. It is called before a Full GC (free_list_only == false) or
183 // before heap shrinking (free_list_only == true).
184 void tear_down_region_sets(bool free_list_only);
185
186 // Rebuilds the region sets / lists so that they are repopulated to
187 // reflect the contents of the heap. The only exception is the
188 // humongous set which was not torn down in the first place. If
189 // free_list_only is true, it will only rebuild the master free
190 // list. It is called after a Full GC (free_list_only == false) or
191 // after heap shrinking (free_list_only == true).
192 void rebuild_region_sets(bool free_list_only);
193
194 // Callback for region mapping changed events.
195 G1RegionMappingChangedListener _listener;
196
197 // Handle G1 NUMA support.
198 G1NUMA* _numa;
199
200 // The sequence of all heap regions in the heap.
201 HeapRegionManager* _hrm;
202
203 // Manages all allocations with regions except humongous object allocations.
204 G1Allocator* _allocator;
205
206 // Manages all heap verification.
207 G1HeapVerifier* _verifier;
208
209 // Outside of GC pauses, the number of bytes used in all regions other
210 // than the current allocation region(s).
211 volatile size_t _summary_bytes_used;
212
213 void increase_used(size_t bytes);
214 void decrease_used(size_t bytes);
215
216 void set_used(size_t bytes);
217
218 // Number of bytes used in all regions during GC. Typically changed when
219 // retiring a GC alloc region.
220 size_t _bytes_used_during_gc;
221
222 // Class that handles archive allocation ranges.
223 G1ArchiveAllocator* _archive_allocator;
224
225 // GC allocation statistics policy for survivors.
226 G1EvacStats _survivor_evac_stats;
227
228 // GC allocation statistics policy for tenured objects.
229 G1EvacStats _old_evac_stats;
230
231 // It specifies whether we should attempt to expand the heap after a
232 // region allocation failure. If heap expansion fails we set this to
233 // false so that we don't re-attempt the heap expansion (it's likely
234 // that subsequent expansion attempts will also fail if one fails).
235 // Currently, it is only consulted during GC and it's reset at the
236 // start of each GC.
237 bool _expand_heap_after_alloc_failure;
238
239 // Helper for monitoring and management support.
240 G1MonitoringSupport* _g1mm;
241
242 // Records whether the region at the given index is (still) a
243 // candidate for eager reclaim. Only valid for humongous start
244 // regions; other regions have unspecified values. Humongous start
245 // regions are initialized at start of collection pause, with
246 // candidates removed from the set as they are found reachable from
247 // roots or the young generation.
248 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
249 protected:
250 bool default_value() const { return false; }
251 public:
252 void clear() { G1BiasedMappedArray<bool>::clear(); }
253 void set_candidate(uint region, bool value) {
254 set_by_index(region, value);
255 }
256 bool is_candidate(uint region) {
257 return get_by_index(region);
258 }
259 };
260
261 HumongousReclaimCandidates _humongous_reclaim_candidates;
262 // Stores whether during humongous object registration we found candidate regions.
263 // If not, we can skip a few steps.
264 bool _has_humongous_reclaim_candidates;
265
266 G1HRPrinter _hr_printer;
267
268 // Return true if an explicit GC should start a concurrent cycle instead
269 // of doing a STW full GC. A concurrent cycle should be started if:
270 // (a) cause == _g1_humongous_allocation,
271 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent,
272 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent,
273 // (d) cause == _wb_conc_mark or _wb_breakpoint,
274 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent.
275 bool should_do_concurrent_full_gc(GCCause::Cause cause);
276
277 // Attempt to start a concurrent cycle with the indicated cause.
278 // precondition: should_do_concurrent_full_gc(cause)
279 bool try_collect_concurrently(GCCause::Cause cause,
280 uint gc_counter,
281 uint old_marking_started_before);
282
283 // Return true if should upgrade to full gc after an incremental one.
284 bool should_upgrade_to_full_gc(GCCause::Cause cause);
285
286 // indicates whether we are in young or mixed GC mode
287 G1CollectorState _collector_state;
288
289 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
290 // concurrent cycles) we have started.
291 volatile uint _old_marking_cycles_started;
292
293 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
294 // concurrent cycles) we have completed.
295 volatile uint _old_marking_cycles_completed;
296
297 // This is a non-product method that is helpful for testing. It is
298 // called at the end of a GC and artificially expands the heap by
299 // allocating a number of dead regions. This way we can induce very
300 // frequent marking cycles and stress the cleanup / concurrent
301 // cleanup code more (as all the regions that will be allocated by
302 // this method will be found dead by the marking cycle).
303 void allocate_dummy_regions() PRODUCT_RETURN;
304
305 // If the HR printer is active, dump the state of the regions in the
306 // heap after a compaction.
307 void print_hrm_post_compaction();
308
309 // Create a memory mapper for auxiliary data structures of the given size and
310 // translation factor.
311 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
312 size_t size,
313 size_t translation_factor);
314
315 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
316
317 // These are macros so that, if the assert fires, we get the correct
318 // line number, file, etc.
319
320 #define heap_locking_asserts_params(_extra_message_) \
321 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
322 (_extra_message_), \
323 BOOL_TO_STR(Heap_lock->owned_by_self()), \
324 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
325 BOOL_TO_STR(Thread::current()->is_VM_thread())
326
327 #define assert_heap_locked() \
328 do { \
329 assert(Heap_lock->owned_by_self(), \
330 heap_locking_asserts_params("should be holding the Heap_lock")); \
331 } while (0)
332
333 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
334 do { \
335 assert(Heap_lock->owned_by_self() || \
336 (SafepointSynchronize::is_at_safepoint() && \
337 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
338 heap_locking_asserts_params("should be holding the Heap_lock or " \
339 "should be at a safepoint")); \
340 } while (0)
341
342 #define assert_heap_locked_and_not_at_safepoint() \
343 do { \
344 assert(Heap_lock->owned_by_self() && \
345 !SafepointSynchronize::is_at_safepoint(), \
346 heap_locking_asserts_params("should be holding the Heap_lock and " \
347 "should not be at a safepoint")); \
348 } while (0)
349
350 #define assert_heap_not_locked() \
351 do { \
352 assert(!Heap_lock->owned_by_self(), \
353 heap_locking_asserts_params("should not be holding the Heap_lock")); \
354 } while (0)
355
356 #define assert_heap_not_locked_and_not_at_safepoint() \
357 do { \
358 assert(!Heap_lock->owned_by_self() && \
359 !SafepointSynchronize::is_at_safepoint(), \
360 heap_locking_asserts_params("should not be holding the Heap_lock and " \
361 "should not be at a safepoint")); \
362 } while (0)
363
364 #define assert_at_safepoint_on_vm_thread() \
365 do { \
366 assert_at_safepoint(); \
367 assert(Thread::current_or_null() != NULL, "no current thread"); \
368 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
369 } while (0)
370
371 #ifdef ASSERT
372 #define assert_used_and_recalculate_used_equal(g1h) \
373 do { \
374 size_t cur_used_bytes = g1h->used(); \
375 size_t recal_used_bytes = g1h->recalculate_used(); \
376 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \
377 " same as recalculated used(" SIZE_FORMAT ").", \
378 cur_used_bytes, recal_used_bytes); \
379 } while (0)
380 #else
381 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0)
382 #endif
383
384 const char* young_gc_name() const;
385
386 // The young region list.
387 G1EdenRegions _eden;
388 G1SurvivorRegions _survivor;
389
390 STWGCTimer* _gc_timer_stw;
391
392 G1NewTracer* _gc_tracer_stw;
393
394 // The current policy object for the collector.
395 G1Policy* _policy;
396 G1HeapSizingPolicy* _heap_sizing_policy;
397
398 G1CollectionSet _collection_set;
399
400 // Try to allocate a single non-humongous HeapRegion sufficient for
401 // an allocation of the given word_size. If do_expand is true,
402 // attempt to expand the heap if necessary to satisfy the allocation
403 // request. 'type' takes the type of region to be allocated. (Use constants
404 // Old, Eden, Humongous, Survivor defined in HeapRegionType.)
405 HeapRegion* new_region(size_t word_size,
406 HeapRegionType type,
407 bool do_expand,
408 uint node_index = G1NUMA::AnyNodeIndex);
409
410 // Initialize a contiguous set of free regions of length num_regions
411 // and starting at index first so that they appear as a single
412 // humongous region.
413 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
414 uint num_regions,
415 size_t word_size);
416
417 // Attempt to allocate a humongous object of the given size. Return
418 // NULL if unsuccessful.
419 HeapWord* humongous_obj_allocate(size_t word_size);
420
421 // The following two methods, allocate_new_tlab() and
422 // mem_allocate(), are the two main entry points from the runtime
423 // into the G1's allocation routines. They have the following
424 // assumptions:
425 //
426 // * They should both be called outside safepoints.
427 //
428 // * They should both be called without holding the Heap_lock.
429 //
430 // * All allocation requests for new TLABs should go to
431 // allocate_new_tlab().
432 //
433 // * All non-TLAB allocation requests should go to mem_allocate().
434 //
435 // * If either call cannot satisfy the allocation request using the
436 // current allocating region, they will try to get a new one. If
437 // this fails, they will attempt to do an evacuation pause and
438 // retry the allocation.
439 //
440 // * If all allocation attempts fail, even after trying to schedule
441 // an evacuation pause, allocate_new_tlab() will return NULL,
442 // whereas mem_allocate() will attempt a heap expansion and/or
443 // schedule a Full GC.
444 //
445 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
446 // should never be called with word_size being humongous. All
447 // humongous allocation requests should go to mem_allocate() which
448 // will satisfy them with a special path.
449
450 virtual HeapWord* allocate_new_tlab(size_t min_size,
451 size_t requested_size,
452 size_t* actual_size);
453
454 virtual HeapWord* mem_allocate(size_t word_size,
455 bool* gc_overhead_limit_was_exceeded);
456
457 // First-level mutator allocation attempt: try to allocate out of
458 // the mutator alloc region without taking the Heap_lock. This
459 // should only be used for non-humongous allocations.
460 inline HeapWord* attempt_allocation(size_t min_word_size,
461 size_t desired_word_size,
462 size_t* actual_word_size);
463
464 // Second-level mutator allocation attempt: take the Heap_lock and
465 // retry the allocation attempt, potentially scheduling a GC
466 // pause. This should only be used for non-humongous allocations.
467 HeapWord* attempt_allocation_slow(size_t word_size);
468
469 // Takes the Heap_lock and attempts a humongous allocation. It can
470 // potentially schedule a GC pause.
471 HeapWord* attempt_allocation_humongous(size_t word_size);
472
473 // Allocation attempt that should be called during safepoints (e.g.,
474 // at the end of a successful GC). expect_null_mutator_alloc_region
475 // specifies whether the mutator alloc region is expected to be NULL
476 // or not.
477 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
478 bool expect_null_mutator_alloc_region);
479
480 // These methods are the "callbacks" from the G1AllocRegion class.
481
482 // For mutator alloc regions.
483 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index);
484 void retire_mutator_alloc_region(HeapRegion* alloc_region,
485 size_t allocated_bytes);
486
487 // For GC alloc regions.
488 bool has_more_regions(G1HeapRegionAttr dest);
489 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index);
490 void retire_gc_alloc_region(HeapRegion* alloc_region,
491 size_t allocated_bytes, G1HeapRegionAttr dest);
492
493 // - if explicit_gc is true, the GC is for a System.gc() etc,
494 // otherwise it's for a failed allocation.
495 // - if clear_all_soft_refs is true, all soft references should be
496 // cleared during the GC.
497 // - it returns false if it is unable to do the collection due to the
498 // GC locker being active, true otherwise.
499 bool do_full_collection(bool explicit_gc,
500 bool clear_all_soft_refs);
501
502 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
503 virtual void do_full_collection(bool clear_all_soft_refs);
504
505 // Callback from VM_G1CollectForAllocation operation.
506 // This function does everything necessary/possible to satisfy a
507 // failed allocation request (including collection, expansion, etc.)
508 HeapWord* satisfy_failed_allocation(size_t word_size,
509 bool* succeeded);
510 // Internal helpers used during full GC to split it up to
511 // increase readability.
512 void abort_concurrent_cycle();
513 void verify_before_full_collection(bool explicit_gc);
514 void prepare_heap_for_full_collection();
515 void prepare_heap_for_mutators();
516 void abort_refinement();
517 void verify_after_full_collection();
518 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
519
520 // Helper method for satisfy_failed_allocation()
521 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
522 bool do_gc,
523 bool clear_all_soft_refs,
524 bool expect_null_mutator_alloc_region,
525 bool* gc_succeeded);
526
527 // Attempting to expand the heap sufficiently
528 // to support an allocation of the given "word_size". If
529 // successful, perform the allocation and return the address of the
530 // allocated block, or else "NULL".
531 HeapWord* expand_and_allocate(size_t word_size);
532
533 // Process any reference objects discovered.
534 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
535
536 // If during a concurrent start pause we may install a pending list head which is not
537 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking
538 // to discover.
539 void make_pending_list_reachable();
540
541 // Merges the information gathered on a per-thread basis for all worker threads
542 // during GC into global variables.
543 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
544
545 void verify_numa_regions(const char* desc);
546
547 public:
548 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
549
550 WorkGang* workers() const { return _workers; }
551
552 // Runs the given AbstractGangTask with the current active workers.
553 virtual void run_task(AbstractGangTask* task);
554
555 // Runs the given AbstractGangTask with the current active workers,
556 // returning the total time taken.
557 Tickspan run_task_timed(AbstractGangTask* task);
558
559 G1Allocator* allocator() {
560 return _allocator;
561 }
562
563 G1HeapVerifier* verifier() {
564 return _verifier;
565 }
566
567 G1MonitoringSupport* g1mm() {
568 assert(_g1mm != NULL, "should have been initialized");
569 return _g1mm;
570 }
571
572 void resize_heap_if_necessary();
573
574 G1NUMA* numa() const { return _numa; }
575
576 // Expand the garbage-first heap by at least the given size (in bytes!).
577 // Returns true if the heap was expanded by the requested amount;
578 // false otherwise.
579 // (Rounds up to a HeapRegion boundary.)
580 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
581 bool expand_single_region(uint node_index);
582
583 // Returns the PLAB statistics for a given destination.
584 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest);
585
586 // Determines PLAB size for a given destination.
587 inline size_t desired_plab_sz(G1HeapRegionAttr dest);
588
589 // Do anything common to GC's.
590 void gc_prologue(bool full);
591 void gc_epilogue(bool full);
592
593 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
594 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
595
596 // Modify the reclaim candidate set and test for presence.
597 // These are only valid for starts_humongous regions.
598 inline void set_humongous_reclaim_candidate(uint region, bool value);
599 inline bool is_humongous_reclaim_candidate(uint region);
600 inline void set_has_humongous_reclaim_candidate(bool value);
601
602 // Remove from the reclaim candidate set. Also remove from the
603 // collection set so that later encounters avoid the slow path.
604 inline void set_humongous_is_live(oop obj);
605
606 // Register the given region to be part of the collection set.
607 inline void register_humongous_region_with_region_attr(uint index);
608
609 // We register a region with the fast "in collection set" test. We
610 // simply set to true the array slot corresponding to this region.
611 void register_young_region_with_region_attr(HeapRegion* r) {
612 _region_attr.set_in_young(r->hrm_index());
613 }
614 inline void register_region_with_region_attr(HeapRegion* r);
615 inline void register_old_region_with_region_attr(HeapRegion* r);
616 inline void register_optional_region_with_region_attr(HeapRegion* r);
617
618 void clear_region_attr(const HeapRegion* hr) {
619 _region_attr.clear(hr);
620 }
621
622 void clear_region_attr() {
623 _region_attr.clear();
624 }
625
626 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking
627 // for all regions.
628 void verify_region_attr_remset_update() PRODUCT_RETURN;
629
630 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
631
632 // This is called at the start of either a concurrent cycle or a Full
633 // GC to update the number of old marking cycles started.
634 void increment_old_marking_cycles_started();
635
636 // This is called at the end of either a concurrent cycle or a Full
637 // GC to update the number of old marking cycles completed. Those two
638 // can happen in a nested fashion, i.e., we start a concurrent
639 // cycle, a Full GC happens half-way through it which ends first,
640 // and then the cycle notices that a Full GC happened and ends
641 // too. The concurrent parameter is a boolean to help us do a bit
642 // tighter consistency checking in the method. If concurrent is
643 // false, the caller is the inner caller in the nesting (i.e., the
644 // Full GC). If concurrent is true, the caller is the outer caller
645 // in this nesting (i.e., the concurrent cycle). Further nesting is
646 // not currently supported. The end of this call also notifies
647 // the G1OldGCCount_lock in case a Java thread is waiting for a full
648 // GC to happen (e.g., it called System.gc() with
649 // +ExplicitGCInvokesConcurrent).
650 void increment_old_marking_cycles_completed(bool concurrent);
651
652 uint old_marking_cycles_completed() {
653 return _old_marking_cycles_completed;
654 }
655
656 G1HRPrinter* hr_printer() { return &_hr_printer; }
657
658 // Allocates a new heap region instance.
659 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
660
661 // Allocate the highest free region in the reserved heap. This will commit
662 // regions as necessary.
663 HeapRegion* alloc_highest_free_region();
664
665 // Frees a region by resetting its metadata and adding it to the free list
666 // passed as a parameter (this is usually a local list which will be appended
667 // to the master free list later or NULL if free list management is handled
668 // in another way).
669 // Callers must ensure they are the only one calling free on the given region
670 // at the same time.
671 void free_region(HeapRegion* hr, FreeRegionList* free_list);
672
673 // It dirties the cards that cover the block so that the post
674 // write barrier never queues anything when updating objects on this
675 // block. It is assumed (and in fact we assert) that the block
676 // belongs to a young region.
677 inline void dirty_young_block(HeapWord* start, size_t word_size);
678
679 // Frees a humongous region by collapsing it into individual regions
680 // and calling free_region() for each of them. The freed regions
681 // will be added to the free list that's passed as a parameter (this
682 // is usually a local list which will be appended to the master free
683 // list later).
684 // The method assumes that only a single thread is ever calling
685 // this for a particular region at once.
686 void free_humongous_region(HeapRegion* hr,
687 FreeRegionList* free_list);
688
689 // Facility for allocating in 'archive' regions in high heap memory and
690 // recording the allocated ranges. These should all be called from the
691 // VM thread at safepoints, without the heap lock held. They can be used
692 // to create and archive a set of heap regions which can be mapped at the
693 // same fixed addresses in a subsequent JVM invocation.
694 void begin_archive_alloc_range(bool open = false);
695
696 // Check if the requested size would be too large for an archive allocation.
697 bool is_archive_alloc_too_large(size_t word_size);
698
699 // Allocate memory of the requested size from the archive region. This will
700 // return NULL if the size is too large or if no memory is available. It
701 // does not trigger a garbage collection.
702 HeapWord* archive_mem_allocate(size_t word_size);
703
704 // Optionally aligns the end address and returns the allocated ranges in
705 // an array of MemRegions in order of ascending addresses.
706 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
707 size_t end_alignment_in_bytes = 0);
708
709 // Facility for allocating a fixed range within the heap and marking
710 // the containing regions as 'archive'. For use at JVM init time, when the
711 // caller may mmap archived heap data at the specified range(s).
712 // Verify that the MemRegions specified in the argument array are within the
713 // reserved heap.
714 bool check_archive_addresses(MemRegion* range, size_t count);
715
716 // Commit the appropriate G1 regions containing the specified MemRegions
717 // and mark them as 'archive' regions. The regions in the array must be
718 // non-overlapping and in order of ascending address.
719 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
720
721 // Insert any required filler objects in the G1 regions around the specified
722 // ranges to make the regions parseable. This must be called after
723 // alloc_archive_regions, and after class loading has occurred.
724 void fill_archive_regions(MemRegion* range, size_t count);
725
726 // For each of the specified MemRegions, uncommit the containing G1 regions
727 // which had been allocated by alloc_archive_regions. This should be called
728 // rather than fill_archive_regions at JVM init time if the archive file
729 // mapping failed, with the same non-overlapping and sorted MemRegion array.
730 void dealloc_archive_regions(MemRegion* range, size_t count);
731
732 oop materialize_archived_object(oop obj);
733
734 private:
735
736 // Shrink the garbage-first heap by at most the given size (in bytes!).
737 // (Rounds down to a HeapRegion boundary.)
738 void shrink(size_t shrink_bytes);
739 void shrink_helper(size_t expand_bytes);
740
741 #if TASKQUEUE_STATS
742 static void print_taskqueue_stats_hdr(outputStream* const st);
743 void print_taskqueue_stats() const;
744 void reset_taskqueue_stats();
745 #endif // TASKQUEUE_STATS
746
747 // Schedule the VM operation that will do an evacuation pause to
748 // satisfy an allocation request of word_size. *succeeded will
749 // return whether the VM operation was successful (it did do an
750 // evacuation pause) or not (another thread beat us to it or the GC
751 // locker was active). Given that we should not be holding the
752 // Heap_lock when we enter this method, we will pass the
753 // gc_count_before (i.e., total_collections()) as a parameter since
754 // it has to be read while holding the Heap_lock. Currently, both
755 // methods that call do_collection_pause() release the Heap_lock
756 // before the call, so it's easy to read gc_count_before just before.
757 HeapWord* do_collection_pause(size_t word_size,
758 uint gc_count_before,
759 bool* succeeded,
760 GCCause::Cause gc_cause);
761
762 void wait_for_root_region_scanning();
763
764 // Perform an incremental collection at a safepoint, possibly
765 // followed by a by-policy upgrade to a full collection. Returns
766 // false if unable to do the collection due to the GC locker being
767 // active, true otherwise.
768 // precondition: at safepoint on VM thread
769 // precondition: !is_gc_active()
770 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
771
772 // Helper for do_collection_pause_at_safepoint, containing the guts
773 // of the incremental collection pause, executed by the vm thread.
774 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms);
775
776 G1HeapVerifier::G1VerifyType young_collection_verify_type() const;
777 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type);
778 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type);
779
780 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms);
781
782 // Actually do the work of evacuating the parts of the collection set.
783 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states);
784 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
785 private:
786 // Evacuate the next set of optional regions.
787 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states);
788
789 public:
790 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
791 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
792 G1RedirtyCardsQueueSet* rdcqs,
793 G1ParScanThreadStateSet* pss);
794
795 void expand_heap_after_young_collection();
796 // Update object copying statistics.
797 void record_obj_copy_mem_stats();
798
799 // The hot card cache for remembered set insertion optimization.
800 G1HotCardCache* _hot_card_cache;
801
802 // The g1 remembered set of the heap.
803 G1RemSet* _rem_set;
804
805 // After a collection pause, convert the regions in the collection set into free
806 // regions.
807 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
808
809 // Abandon the current collection set without recording policy
810 // statistics or updating free lists.
811 void abandon_collection_set(G1CollectionSet* collection_set);
812
813 // The concurrent marker (and the thread it runs in.)
814 G1ConcurrentMark* _cm;
815 G1ConcurrentMarkThread* _cm_thread;
816
817 // The concurrent refiner.
818 G1ConcurrentRefine* _cr;
819
820 // The parallel task queues
821 G1ScannerTasksQueueSet *_task_queues;
822
823 // True iff a evacuation has failed in the current collection.
824 bool _evacuation_failed;
825
826 EvacuationFailedInfo* _evacuation_failed_info_array;
827
828 // Failed evacuations cause some logical from-space objects to have
829 // forwarding pointers to themselves. Reset them.
830 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs);
831
832 // Restore the objects in the regions in the collection set after an
833 // evacuation failure.
834 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs);
835
836 PreservedMarksSet _preserved_marks_set;
837
838 // Preserve the mark of "obj", if necessary, in preparation for its mark
839 // word being overwritten with a self-forwarding-pointer.
840 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m);
841
842 #ifndef PRODUCT
843 // Support for forcing evacuation failures. Analogous to
844 // PromotionFailureALot for the other collectors.
845
846 // Records whether G1EvacuationFailureALot should be in effect
847 // for the current GC
848 bool _evacuation_failure_alot_for_current_gc;
849
850 // Used to record the GC number for interval checking when
851 // determining whether G1EvaucationFailureALot is in effect
852 // for the current GC.
853 size_t _evacuation_failure_alot_gc_number;
854
855 // Count of the number of evacuations between failures.
856 volatile size_t _evacuation_failure_alot_count;
857
858 // Set whether G1EvacuationFailureALot should be in effect
859 // for the current GC (based upon the type of GC and which
860 // command line flags are set);
861 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
862 bool during_concurrent_start,
863 bool mark_or_rebuild_in_progress);
864
865 inline void set_evacuation_failure_alot_for_current_gc();
866
867 // Return true if it's time to cause an evacuation failure.
868 inline bool evacuation_should_fail();
869
870 // Reset the G1EvacuationFailureALot counters. Should be called at
871 // the end of an evacuation pause in which an evacuation failure occurred.
872 inline void reset_evacuation_should_fail();
873 #endif // !PRODUCT
874
875 // ("Weak") Reference processing support.
876 //
877 // G1 has 2 instances of the reference processor class. One
878 // (_ref_processor_cm) handles reference object discovery
879 // and subsequent processing during concurrent marking cycles.
880 //
881 // The other (_ref_processor_stw) handles reference object
882 // discovery and processing during full GCs and incremental
883 // evacuation pauses.
884 //
885 // During an incremental pause, reference discovery will be
886 // temporarily disabled for _ref_processor_cm and will be
887 // enabled for _ref_processor_stw. At the end of the evacuation
888 // pause references discovered by _ref_processor_stw will be
889 // processed and discovery will be disabled. The previous
890 // setting for reference object discovery for _ref_processor_cm
891 // will be re-instated.
892 //
893 // At the start of marking:
894 // * Discovery by the CM ref processor is verified to be inactive
895 // and it's discovered lists are empty.
896 // * Discovery by the CM ref processor is then enabled.
897 //
898 // At the end of marking:
899 // * Any references on the CM ref processor's discovered
900 // lists are processed (possibly MT).
901 //
902 // At the start of full GC we:
903 // * Disable discovery by the CM ref processor and
904 // empty CM ref processor's discovered lists
905 // (without processing any entries).
906 // * Verify that the STW ref processor is inactive and it's
907 // discovered lists are empty.
908 // * Temporarily set STW ref processor discovery as single threaded.
909 // * Temporarily clear the STW ref processor's _is_alive_non_header
910 // field.
911 // * Finally enable discovery by the STW ref processor.
912 //
913 // The STW ref processor is used to record any discovered
914 // references during the full GC.
915 //
916 // At the end of a full GC we:
917 // * Enqueue any reference objects discovered by the STW ref processor
918 // that have non-live referents. This has the side-effect of
919 // making the STW ref processor inactive by disabling discovery.
920 // * Verify that the CM ref processor is still inactive
921 // and no references have been placed on it's discovered
922 // lists (also checked as a precondition during concurrent start).
923
924 // The (stw) reference processor...
925 ReferenceProcessor* _ref_processor_stw;
926
927 // During reference object discovery, the _is_alive_non_header
928 // closure (if non-null) is applied to the referent object to
929 // determine whether the referent is live. If so then the
930 // reference object does not need to be 'discovered' and can
931 // be treated as a regular oop. This has the benefit of reducing
932 // the number of 'discovered' reference objects that need to
933 // be processed.
934 //
935 // Instance of the is_alive closure for embedding into the
936 // STW reference processor as the _is_alive_non_header field.
937 // Supplying a value for the _is_alive_non_header field is
938 // optional but doing so prevents unnecessary additions to
939 // the discovered lists during reference discovery.
940 G1STWIsAliveClosure _is_alive_closure_stw;
941
942 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
943
944 // The (concurrent marking) reference processor...
945 ReferenceProcessor* _ref_processor_cm;
946
947 // Instance of the concurrent mark is_alive closure for embedding
948 // into the Concurrent Marking reference processor as the
949 // _is_alive_non_header field. Supplying a value for the
950 // _is_alive_non_header field is optional but doing so prevents
951 // unnecessary additions to the discovered lists during reference
952 // discovery.
953 G1CMIsAliveClosure _is_alive_closure_cm;
954
955 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
956 public:
957
958 G1ScannerTasksQueue* task_queue(uint i) const;
959
960 uint num_task_queues() const;
961
962 // Create a G1CollectedHeap.
963 // Must call the initialize method afterwards.
964 // May not return if something goes wrong.
965 G1CollectedHeap();
966
967 private:
968 jint initialize_concurrent_refinement();
969 jint initialize_young_gen_sampling_thread();
970 public:
971 // Initialize the G1CollectedHeap to have the initial and
972 // maximum sizes and remembered and barrier sets
973 // specified by the policy object.
974 jint initialize();
975
976 virtual void stop();
977 virtual void safepoint_synchronize_begin();
978 virtual void safepoint_synchronize_end();
979
980 // Does operations required after initialization has been done.
981 void post_initialize();
982
983 // Initialize weak reference processing.
984 void ref_processing_init();
985
986 virtual Name kind() const {
987 return CollectedHeap::G1;
988 }
989
990 virtual const char* name() const {
991 return "G1";
992 }
993
994 const G1CollectorState* collector_state() const { return &_collector_state; }
995 G1CollectorState* collector_state() { return &_collector_state; }
996
997 // The current policy object for the collector.
998 G1Policy* policy() const { return _policy; }
999 // The remembered set.
1000 G1RemSet* rem_set() const { return _rem_set; }
1001
1002 inline G1GCPhaseTimes* phase_times() const;
1003
1004 HeapRegionManager* hrm() const { return _hrm; }
1005
1006 const G1CollectionSet* collection_set() const { return &_collection_set; }
1007 G1CollectionSet* collection_set() { return &_collection_set; }
1008
1009 virtual SoftRefPolicy* soft_ref_policy();
1010
1011 virtual void initialize_serviceability();
1012 virtual MemoryUsage memory_usage();
1013 virtual GrowableArray<GCMemoryManager*> memory_managers();
1014 virtual GrowableArray<MemoryPool*> memory_pools();
1015
1016 // Try to minimize the remembered set.
1017 void scrub_rem_set();
1018
1019 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1020 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id);
1021
1022 // The shared block offset table array.
1023 G1BlockOffsetTable* bot() const { return _bot; }
1024
1025 // Reference Processing accessors
1026
1027 // The STW reference processor....
1028 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1029
1030 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1031
1032 // The Concurrent Marking reference processor...
1033 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1034
1035 size_t unused_committed_regions_in_bytes() const;
1036
1037 virtual size_t capacity() const;
1038 virtual size_t used() const;
1039 // This should be called when we're not holding the heap lock. The
1040 // result might be a bit inaccurate.
1041 size_t used_unlocked() const;
1042 size_t recalculate_used() const;
1043
1044 // These virtual functions do the actual allocation.
1045 // Some heaps may offer a contiguous region for shared non-blocking
1046 // allocation, via inlined code (by exporting the address of the top and
1047 // end fields defining the extent of the contiguous allocation region.)
1048 // But G1CollectedHeap doesn't yet support this.
1049
1050 virtual bool is_maximal_no_gc() const {
1051 return _hrm->available() == 0;
1052 }
1053
1054 // Returns whether there are any regions left in the heap for allocation.
1055 bool has_regions_left_for_allocation() const {
1056 return !is_maximal_no_gc() || num_free_regions() != 0;
1057 }
1058
1059 // The current number of regions in the heap.
1060 uint num_regions() const { return _hrm->length(); }
1061
1062 // The max number of regions in the heap.
1063 uint max_regions() const { return _hrm->max_length(); }
1064
1065 // Max number of regions that can be comitted.
1066 uint max_expandable_regions() const { return _hrm->max_expandable_length(); }
1067
1068 // The number of regions that are completely free.
1069 uint num_free_regions() const { return _hrm->num_free_regions(); }
1070
1071 // The number of regions that can be allocated into.
1072 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); }
1073
1074 MemoryUsage get_auxiliary_data_memory_usage() const {
1075 return _hrm->get_auxiliary_data_memory_usage();
1076 }
1077
1078 // The number of regions that are not completely free.
1079 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1080
1081 #ifdef ASSERT
1082 bool is_on_master_free_list(HeapRegion* hr) {
1083 return _hrm->is_free(hr);
1084 }
1085 #endif // ASSERT
1086
1087 inline void old_set_add(HeapRegion* hr);
1088 inline void old_set_remove(HeapRegion* hr);
1089
1090 inline void archive_set_add(HeapRegion* hr);
1091
1092 size_t non_young_capacity_bytes() {
1093 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1094 }
1095
1096 // Determine whether the given region is one that we are using as an
1097 // old GC alloc region.
1098 bool is_old_gc_alloc_region(HeapRegion* hr);
1099
1100 // Perform a collection of the heap; intended for use in implementing
1101 // "System.gc". This probably implies as full a collection as the
1102 // "CollectedHeap" supports.
1103 virtual void collect(GCCause::Cause cause);
1104
1105 // Perform a collection of the heap with the given cause.
1106 // Returns whether this collection actually executed.
1107 bool try_collect(GCCause::Cause cause);
1108
1109 // True iff an evacuation has failed in the most-recent collection.
1110 bool evacuation_failed() { return _evacuation_failed; }
1111
1112 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1113 void prepend_to_freelist(FreeRegionList* list);
1114 void decrement_summary_bytes(size_t bytes);
1115
1116 virtual bool is_in(const void* p) const;
1117 #ifdef ASSERT
1118 // Returns whether p is in one of the available areas of the heap. Slow but
1119 // extensive version.
1120 bool is_in_exact(const void* p) const;
1121 #endif
1122
1123 // Return "TRUE" iff the given object address is within the collection
1124 // set. Assumes that the reference points into the heap.
1125 inline bool is_in_cset(const HeapRegion *hr);
1126 inline bool is_in_cset(oop obj);
1127 inline bool is_in_cset(HeapWord* addr);
1128
1129 inline bool is_in_cset_or_humongous(const oop obj);
1130
1131 private:
1132 // This array is used for a quick test on whether a reference points into
1133 // the collection set or not. Each of the array's elements denotes whether the
1134 // corresponding region is in the collection set or not.
1135 G1HeapRegionAttrBiasedMappedArray _region_attr;
1136
1137 public:
1138
1139 inline G1HeapRegionAttr region_attr(const void* obj) const;
1140 inline G1HeapRegionAttr region_attr(uint idx) const;
1141
1142 // Return "TRUE" iff the given object address is in the reserved
1143 // region of g1.
1144 bool is_in_g1_reserved(const void* p) const {
1145 return _hrm->reserved().contains(p);
1146 }
1147
1148 // Returns a MemRegion that corresponds to the space that has been
1149 // reserved for the heap
1150 MemRegion g1_reserved() const {
1151 return _hrm->reserved();
1152 }
1153
1154 MemRegion reserved_region() const {
1155 return _reserved;
1156 }
1157
1158 HeapWord* base() const {
1159 return _reserved.start();
1160 }
1161
1162 bool is_in_reserved(const void* addr) const {
1163 return _reserved.contains(addr);
1164 }
1165
1166 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; }
1167
1168 G1CardTable* card_table() const {
1169 return _card_table;
1170 }
1171
1172 // Iteration functions.
1173
1174 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer);
1175
1176 // Iterate over all objects, calling "cl.do_object" on each.
1177 virtual void object_iterate(ObjectClosure* cl);
1178
1179 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num);
1180
1181 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
1182 virtual void keep_alive(oop obj);
1183
1184 // Iterate over heap regions, in address order, terminating the
1185 // iteration early if the "do_heap_region" method returns "true".
1186 void heap_region_iterate(HeapRegionClosure* blk) const;
1187
1188 // Return the region with the given index. It assumes the index is valid.
1189 inline HeapRegion* region_at(uint index) const;
1190 inline HeapRegion* region_at_or_null(uint index) const;
1191
1192 // Return the next region (by index) that is part of the same
1193 // humongous object that hr is part of.
1194 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1195
1196 // Calculate the region index of the given address. Given address must be
1197 // within the heap.
1198 inline uint addr_to_region(HeapWord* addr) const;
1199
1200 inline HeapWord* bottom_addr_for_region(uint index) const;
1201
1202 // Two functions to iterate over the heap regions in parallel. Threads
1203 // compete using the HeapRegionClaimer to claim the regions before
1204 // applying the closure on them.
1205 // The _from_worker_offset version uses the HeapRegionClaimer and
1206 // the worker id to calculate a start offset to prevent all workers to
1207 // start from the point.
1208 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1209 HeapRegionClaimer* hrclaimer,
1210 uint worker_id) const;
1211
1212 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1213 HeapRegionClaimer* hrclaimer) const;
1214
1215 // Iterate over all regions in the collection set in parallel.
1216 void collection_set_par_iterate_all(HeapRegionClosure* cl,
1217 HeapRegionClaimer* hr_claimer,
1218 uint worker_id);
1219
1220 // Iterate over all regions currently in the current collection set.
1221 void collection_set_iterate_all(HeapRegionClosure* blk);
1222
1223 // Iterate over the regions in the current increment of the collection set.
1224 // Starts the iteration so that the start regions of a given worker id over the
1225 // set active_workers are evenly spread across the set of collection set regions
1226 // to be iterated.
1227 // The variant with the HeapRegionClaimer guarantees that the closure will be
1228 // applied to a particular region exactly once.
1229 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) {
1230 collection_set_iterate_increment_from(blk, NULL, worker_id);
1231 }
1232 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
1233
1234 // Returns the HeapRegion that contains addr. addr must not be NULL.
1235 template <class T>
1236 inline HeapRegion* heap_region_containing(const T addr) const;
1237
1238 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1239 // region. addr must not be NULL.
1240 template <class T>
1241 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1242
1243 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1244 // each address in the (reserved) heap is a member of exactly
1245 // one block. The defining characteristic of a block is that it is
1246 // possible to find its size, and thus to progress forward to the next
1247 // block. (Blocks may be of different sizes.) Thus, blocks may
1248 // represent Java objects, or they might be free blocks in a
1249 // free-list-based heap (or subheap), as long as the two kinds are
1250 // distinguishable and the size of each is determinable.
1251
1252 // Returns the address of the start of the "block" that contains the
1253 // address "addr". We say "blocks" instead of "object" since some heaps
1254 // may not pack objects densely; a chunk may either be an object or a
1255 // non-object.
1256 HeapWord* block_start(const void* addr) const;
1257
1258 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1259 // the block is an object.
1260 bool block_is_obj(const HeapWord* addr) const;
1261
1262 // Section on thread-local allocation buffers (TLABs)
1263 // See CollectedHeap for semantics.
1264
1265 bool supports_tlab_allocation() const;
1266 size_t tlab_capacity(Thread* ignored) const;
1267 size_t tlab_used(Thread* ignored) const;
1268 size_t max_tlab_size() const;
1269 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1270
1271 inline bool is_in_young(const oop obj);
1272
1273 // Returns "true" iff the given word_size is "very large".
1274 static bool is_humongous(size_t word_size) {
1275 // Note this has to be strictly greater-than as the TLABs
1276 // are capped at the humongous threshold and we want to
1277 // ensure that we don't try to allocate a TLAB as
1278 // humongous and that we don't allocate a humongous
1279 // object in a TLAB.
1280 return word_size > _humongous_object_threshold_in_words;
1281 }
1282
1283 // Returns the humongous threshold for a specific region size
1284 static size_t humongous_threshold_for(size_t region_size) {
1285 return (region_size / 2);
1286 }
1287
1288 // Returns the number of regions the humongous object of the given word size
1289 // requires.
1290 static size_t humongous_obj_size_in_regions(size_t word_size);
1291
1292 // Print the maximum heap capacity.
1293 virtual size_t max_capacity() const;
1294
1295 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used.
1296 virtual size_t max_reserved_capacity() const;
1297
1298 virtual jlong millis_since_last_gc();
1299
1300
1301 // Convenience function to be used in situations where the heap type can be
1302 // asserted to be this type.
1303 static G1CollectedHeap* heap() {
1304 return named_heap<G1CollectedHeap>(CollectedHeap::G1);
1305 }
1306
1307 void set_region_short_lived_locked(HeapRegion* hr);
1308 // add appropriate methods for any other surv rate groups
1309
1310 const G1SurvivorRegions* survivor() const { return &_survivor; }
1311
1312 uint eden_regions_count() const { return _eden.length(); }
1313 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); }
1314 uint survivor_regions_count() const { return _survivor.length(); }
1315 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); }
1316 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); }
1317 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); }
1318 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1319 uint old_regions_count() const { return _old_set.length(); }
1320 uint archive_regions_count() const { return _archive_set.length(); }
1321 uint humongous_regions_count() const { return _humongous_set.length(); }
1322
1323 #ifdef ASSERT
1324 bool check_young_list_empty();
1325 #endif
1326
1327 // *** Stuff related to concurrent marking. It's not clear to me that so
1328 // many of these need to be public.
1329
1330 // The functions below are helper functions that a subclass of
1331 // "CollectedHeap" can use in the implementation of its virtual
1332 // functions.
1333 // This performs a concurrent marking of the live objects in a
1334 // bitmap off to the side.
1335 void do_concurrent_mark();
1336
1337 bool is_marked_next(oop obj) const;
1338
1339 // Determine if an object is dead, given the object and also
1340 // the region to which the object belongs. An object is dead
1341 // iff a) it was not allocated since the last mark, b) it
1342 // is not marked, and c) it is not in an archive region.
1343 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1344 return
1345 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1346 !hr->is_archive();
1347 }
1348
1349 // This function returns true when an object has been
1350 // around since the previous marking and hasn't yet
1351 // been marked during this marking, and is not in an archive region.
1352 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1353 return
1354 !hr->obj_allocated_since_next_marking(obj) &&
1355 !is_marked_next(obj) &&
1356 !hr->is_archive();
1357 }
1358
1359 // Determine if an object is dead, given only the object itself.
1360 // This will find the region to which the object belongs and
1361 // then call the region version of the same function.
1362
1363 // Added if it is NULL it isn't dead.
1364
1365 inline bool is_obj_dead(const oop obj) const;
1366
1367 inline bool is_obj_ill(const oop obj) const;
1368
1369 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1370 inline bool is_obj_dead_full(const oop obj) const;
1371
1372 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1373
1374 // Refinement
1375
1376 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1377
1378 // Optimized nmethod scanning support routines
1379
1380 // Register the given nmethod with the G1 heap.
1381 virtual void register_nmethod(nmethod* nm);
1382
1383 // Unregister the given nmethod from the G1 heap.
1384 virtual void unregister_nmethod(nmethod* nm);
1385
1386 // No nmethod flushing needed.
1387 virtual void flush_nmethod(nmethod* nm) {}
1388
1389 // No nmethod verification implemented.
1390 virtual void verify_nmethod(nmethod* nm) {}
1391
1392 // Free up superfluous code root memory.
1393 void purge_code_root_memory();
1394
1395 // Rebuild the strong code root lists for each region
1396 // after a full GC.
1397 void rebuild_strong_code_roots();
1398
1399 // Partial cleaning of VM internal data structures.
1400 void string_dedup_cleaning(BoolObjectClosure* is_alive,
1401 OopClosure* keep_alive,
1402 G1GCPhaseTimes* phase_times = NULL);
1403
1404 // Performs cleaning of data structures after class unloading.
1405 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1406
1407 // Redirty logged cards in the refinement queue.
1408 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs);
1409
1410 // Verification
1411
1412 // Deduplicate the string
1413 virtual void deduplicate_string(oop str);
1414
1415 // Perform any cleanup actions necessary before allowing a verification.
1416 virtual void prepare_for_verify();
1417
1418 // Perform verification.
1419
1420 // vo == UsePrevMarking -> use "prev" marking information,
1421 // vo == UseNextMarking -> use "next" marking information
1422 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1423 //
1424 // NOTE: Only the "prev" marking information is guaranteed to be
1425 // consistent most of the time, so most calls to this should use
1426 // vo == UsePrevMarking.
1427 // Currently, there is only one case where this is called with
1428 // vo == UseNextMarking, which is to verify the "next" marking
1429 // information at the end of remark.
1430 // Currently there is only one place where this is called with
1431 // vo == UseFullMarking, which is to verify the marking during a
1432 // full GC.
1433 void verify(VerifyOption vo);
1434
1435 // WhiteBox testing support.
1436 virtual bool supports_concurrent_gc_breakpoints() const;
1437 bool is_heterogeneous_heap() const;
1438
1439 virtual WorkGang* get_safepoint_workers() { return _workers; }
1440
1441 // The methods below are here for convenience and dispatch the
1442 // appropriate method depending on value of the given VerifyOption
1443 // parameter. The values for that parameter, and their meanings,
1444 // are the same as those above.
1445
1446 bool is_obj_dead_cond(const oop obj,
1447 const HeapRegion* hr,
1448 const VerifyOption vo) const;
1449
1450 bool is_obj_dead_cond(const oop obj,
1451 const VerifyOption vo) const;
1452
1453 G1HeapSummary create_g1_heap_summary();
1454 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1455
1456 // Printing
1457 private:
1458 void print_heap_regions() const;
1459 void print_regions_on(outputStream* st) const;
1460
1461 public:
1462 virtual void print_on(outputStream* st) const;
1463 virtual void print_extended_on(outputStream* st) const;
1464 virtual void print_on_error(outputStream* st) const;
1465
1466 virtual void gc_threads_do(ThreadClosure* tc) const;
1467
1468 // Override
1469 void print_tracing_info() const;
1470
1471 // The following two methods are helpful for debugging RSet issues.
1472 void print_cset_rsets() PRODUCT_RETURN;
1473 void print_all_rsets() PRODUCT_RETURN;
1474
1475 // Used to print information about locations in the hs_err file.
1476 virtual bool print_location(outputStream* st, void* addr) const;
1477 };
1478
1479 class G1ParEvacuateFollowersClosure : public VoidClosure {
1480 private:
1481 double _start_term;
1482 double _term_time;
1483 size_t _term_attempts;
1484
1485 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1486 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); }
1487 protected:
1488 G1CollectedHeap* _g1h;
1489 G1ParScanThreadState* _par_scan_state;
1490 G1ScannerTasksQueueSet* _queues;
1491 TaskTerminator* _terminator;
1492 G1GCPhaseTimes::GCParPhases _phase;
1493
1494 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1495 G1ScannerTasksQueueSet* queues() { return _queues; }
1496 TaskTerminator* terminator() { return _terminator; }
1497
1498 public:
1499 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1500 G1ParScanThreadState* par_scan_state,
1501 G1ScannerTasksQueueSet* queues,
1502 TaskTerminator* terminator,
1503 G1GCPhaseTimes::GCParPhases phase)
1504 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1505 _g1h(g1h), _par_scan_state(par_scan_state),
1506 _queues(queues), _terminator(terminator), _phase(phase) {}
1507
1508 void do_void();
1509
1510 double term_time() const { return _term_time; }
1511 size_t term_attempts() const { return _term_attempts; }
1512
1513 private:
1514 inline bool offer_termination();
1515 };
1516
1517 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP