1 /*
2 * Copyright (c) 2001, 2018, 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_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/evacuationInfo.hpp"
29 #include "gc/g1/g1BarrierSet.hpp"
30 #include "gc/g1/g1BiasedArray.hpp"
31 #include "gc/g1/g1CardTable.hpp"
32 #include "gc/g1/g1CollectionSet.hpp"
33 #include "gc/g1/g1CollectorState.hpp"
34 #include "gc/g1/g1ConcurrentMark.hpp"
35 #include "gc/g1/g1EdenRegions.hpp"
36 #include "gc/g1/g1EvacFailure.hpp"
37 #include "gc/g1/g1EvacStats.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/g1InCSetState.hpp"
43 #include "gc/g1/g1MonitoringSupport.hpp"
44 #include "gc/g1/g1SurvivorRegions.hpp"
45 #include "gc/g1/g1YCTypes.hpp"
46 #include "gc/g1/heapRegionManager.hpp"
47 #include "gc/g1/heapRegionSet.hpp"
48 #include "gc/shared/barrierSet.hpp"
49 #include "gc/shared/collectedHeap.hpp"
50 #include "gc/shared/gcHeapSummary.hpp"
51 #include "gc/shared/plab.hpp"
52 #include "gc/shared/preservedMarks.hpp"
53 #include "gc/shared/softRefPolicy.hpp"
54 #include "memory/memRegion.hpp"
55 #include "utilities/stack.hpp"
56
57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
58 // It uses the "Garbage First" heap organization and algorithm, which
59 // may combine concurrent marking with parallel, incremental compaction of
60 // heap subsets that will yield large amounts of garbage.
61
62 // Forward declarations
63 class HeapRegion;
64 class HRRSCleanupTask;
65 class GenerationSpec;
66 class G1ParScanThreadState;
67 class G1ParScanThreadStateSet;
68 class G1ParScanThreadState;
69 class MemoryPool;
70 class MemoryManager;
71 class ObjectClosure;
72 class SpaceClosure;
73 class CompactibleSpaceClosure;
74 class Space;
75 class G1CollectionSet;
76 class G1CollectorPolicy;
77 class G1Policy;
78 class G1HotCardCache;
79 class G1RemSet;
80 class G1YoungRemSetSamplingThread;
81 class HeapRegionRemSetIterator;
82 class G1ConcurrentMark;
83 class G1ConcurrentMarkThread;
84 class G1ConcurrentRefine;
85 class GenerationCounters;
86 class STWGCTimer;
87 class G1NewTracer;
88 class EvacuationFailedInfo;
89 class nmethod;
90 class WorkGang;
91 class G1Allocator;
92 class G1ArchiveAllocator;
93 class G1FullGCScope;
94 class G1HeapVerifier;
95 class G1HeapSizingPolicy;
96 class G1HeapSummary;
97 class G1EvacSummary;
98
99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
101
102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
104
105 // The G1 STW is alive closure.
106 // An instance is embedded into the G1CH and used as the
107 // (optional) _is_alive_non_header closure in the STW
108 // reference processor. It is also extensively used during
109 // reference processing during STW evacuation pauses.
110 class G1STWIsAliveClosure : public BoolObjectClosure {
111 G1CollectedHeap* _g1h;
112 public:
113 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
114 bool do_object_b(oop p);
115 };
116
117 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure {
118 G1CollectedHeap* _g1h;
119 public:
120 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
121 bool do_object_b(oop p);
122 };
123
124 class G1RegionMappingChangedListener : public G1MappingChangedListener {
125 private:
126 void reset_from_card_cache(uint start_idx, size_t num_regions);
127 public:
128 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
129 };
130
131 class G1CollectedHeap : public CollectedHeap {
132 friend class G1FreeCollectionSetTask;
133 friend class VM_CollectForMetadataAllocation;
134 friend class VM_G1CollectForAllocation;
135 friend class VM_G1CollectFull;
136 friend class VMStructs;
137 friend class MutatorAllocRegion;
138 friend class G1FullCollector;
139 friend class G1GCAllocRegion;
140 friend class G1HeapVerifier;
141
142 // Closures used in implementation.
143 friend class G1ParScanThreadState;
144 friend class G1ParScanThreadStateSet;
145 friend class G1ParTask;
146 friend class G1PLABAllocator;
147 friend class G1PrepareCompactClosure;
148
149 // Other related classes.
150 friend class HeapRegionClaimer;
151
152 // Testing classes.
153 friend class G1CheckCSetFastTableClosure;
154
155 private:
156 G1YoungRemSetSamplingThread* _young_gen_sampling_thread;
157
158 WorkGang* _workers;
159 G1CollectorPolicy* _collector_policy;
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 // The sequence of all heap regions in the heap.
198 HeapRegionManager _hrm;
199
200 // Manages all allocations with regions except humongous object allocations.
201 G1Allocator* _allocator;
202
203 // Manages all heap verification.
204 G1HeapVerifier* _verifier;
205
206 // Outside of GC pauses, the number of bytes used in all regions other
207 // than the current allocation region(s).
208 size_t _summary_bytes_used;
209
210 void increase_used(size_t bytes);
211 void decrease_used(size_t bytes);
212
213 void set_used(size_t bytes);
214
215 // Class that handles archive allocation ranges.
216 G1ArchiveAllocator* _archive_allocator;
217
218 // GC allocation statistics policy for survivors.
219 G1EvacStats _survivor_evac_stats;
220
221 // GC allocation statistics policy for tenured objects.
222 G1EvacStats _old_evac_stats;
223
224 // It specifies whether we should attempt to expand the heap after a
225 // region allocation failure. If heap expansion fails we set this to
226 // false so that we don't re-attempt the heap expansion (it's likely
227 // that subsequent expansion attempts will also fail if one fails).
228 // Currently, it is only consulted during GC and it's reset at the
229 // start of each GC.
230 bool _expand_heap_after_alloc_failure;
231
232 // Helper for monitoring and management support.
233 G1MonitoringSupport* _g1mm;
234
235 // Records whether the region at the given index is (still) a
236 // candidate for eager reclaim. Only valid for humongous start
237 // regions; other regions have unspecified values. Humongous start
238 // regions are initialized at start of collection pause, with
239 // candidates removed from the set as they are found reachable from
240 // roots or the young generation.
241 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
242 protected:
243 bool default_value() const { return false; }
244 public:
245 void clear() { G1BiasedMappedArray<bool>::clear(); }
246 void set_candidate(uint region, bool value) {
247 set_by_index(region, value);
248 }
249 bool is_candidate(uint region) {
250 return get_by_index(region);
251 }
252 };
253
254 HumongousReclaimCandidates _humongous_reclaim_candidates;
255 // Stores whether during humongous object registration we found candidate regions.
256 // If not, we can skip a few steps.
257 bool _has_humongous_reclaim_candidates;
258
259 G1HRPrinter _hr_printer;
260
261 // It decides whether an explicit GC should start a concurrent cycle
262 // instead of doing a STW GC. Currently, a concurrent cycle is
263 // explicitly started if:
264 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
265 // (b) cause == _g1_humongous_allocation
266 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
267 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
268 // (e) cause == _wb_conc_mark
269 bool should_do_concurrent_full_gc(GCCause::Cause cause);
270
271 // indicates whether we are in young or mixed GC mode
272 G1CollectorState _collector_state;
273
274 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
275 // concurrent cycles) we have started.
276 volatile uint _old_marking_cycles_started;
277
278 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
279 // concurrent cycles) we have completed.
280 volatile uint _old_marking_cycles_completed;
281
282 // This is a non-product method that is helpful for testing. It is
283 // called at the end of a GC and artificially expands the heap by
284 // allocating a number of dead regions. This way we can induce very
285 // frequent marking cycles and stress the cleanup / concurrent
286 // cleanup code more (as all the regions that will be allocated by
287 // this method will be found dead by the marking cycle).
288 void allocate_dummy_regions() PRODUCT_RETURN;
289
290 // If the HR printer is active, dump the state of the regions in the
291 // heap after a compaction.
292 void print_hrm_post_compaction();
293
294 // Create a memory mapper for auxiliary data structures of the given size and
295 // translation factor.
296 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
297 size_t size,
298 size_t translation_factor);
299
300 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
301
302 // These are macros so that, if the assert fires, we get the correct
303 // line number, file, etc.
304
305 #define heap_locking_asserts_params(_extra_message_) \
306 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
307 (_extra_message_), \
308 BOOL_TO_STR(Heap_lock->owned_by_self()), \
309 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
310 BOOL_TO_STR(Thread::current()->is_VM_thread())
311
312 #define assert_heap_locked() \
313 do { \
314 assert(Heap_lock->owned_by_self(), \
315 heap_locking_asserts_params("should be holding the Heap_lock")); \
316 } while (0)
317
318 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
319 do { \
320 assert(Heap_lock->owned_by_self() || \
321 (SafepointSynchronize::is_at_safepoint() && \
322 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
323 heap_locking_asserts_params("should be holding the Heap_lock or " \
324 "should be at a safepoint")); \
325 } while (0)
326
327 #define assert_heap_locked_and_not_at_safepoint() \
328 do { \
329 assert(Heap_lock->owned_by_self() && \
330 !SafepointSynchronize::is_at_safepoint(), \
331 heap_locking_asserts_params("should be holding the Heap_lock and " \
332 "should not be at a safepoint")); \
333 } while (0)
334
335 #define assert_heap_not_locked() \
336 do { \
337 assert(!Heap_lock->owned_by_self(), \
338 heap_locking_asserts_params("should not be holding the Heap_lock")); \
339 } while (0)
340
341 #define assert_heap_not_locked_and_not_at_safepoint() \
342 do { \
343 assert(!Heap_lock->owned_by_self() && \
344 !SafepointSynchronize::is_at_safepoint(), \
345 heap_locking_asserts_params("should not be holding the Heap_lock and " \
346 "should not be at a safepoint")); \
347 } while (0)
348
349 #define assert_at_safepoint_on_vm_thread() \
350 do { \
351 assert_at_safepoint(); \
352 assert(Thread::current_or_null() != NULL, "no current thread"); \
353 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \
354 } while (0)
355
356 // The young region list.
357 G1EdenRegions _eden;
358 G1SurvivorRegions _survivor;
359
360 STWGCTimer* _gc_timer_stw;
361
362 G1NewTracer* _gc_tracer_stw;
363
364 // The current policy object for the collector.
365 G1Policy* _g1_policy;
366 G1HeapSizingPolicy* _heap_sizing_policy;
367
368 G1CollectionSet _collection_set;
369
370 // Try to allocate a single non-humongous HeapRegion sufficient for
371 // an allocation of the given word_size. If do_expand is true,
372 // attempt to expand the heap if necessary to satisfy the allocation
373 // request. If the region is to be used as an old region or for a
374 // humongous object, set is_old to true. If not, to false.
375 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
376
377 // Initialize a contiguous set of free regions of length num_regions
378 // and starting at index first so that they appear as a single
379 // humongous region.
380 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
381 uint num_regions,
382 size_t word_size);
383
384 // Attempt to allocate a humongous object of the given size. Return
385 // NULL if unsuccessful.
386 HeapWord* humongous_obj_allocate(size_t word_size);
387
388 // The following two methods, allocate_new_tlab() and
389 // mem_allocate(), are the two main entry points from the runtime
390 // into the G1's allocation routines. They have the following
391 // assumptions:
392 //
393 // * They should both be called outside safepoints.
394 //
395 // * They should both be called without holding the Heap_lock.
396 //
397 // * All allocation requests for new TLABs should go to
398 // allocate_new_tlab().
399 //
400 // * All non-TLAB allocation requests should go to mem_allocate().
401 //
402 // * If either call cannot satisfy the allocation request using the
403 // current allocating region, they will try to get a new one. If
404 // this fails, they will attempt to do an evacuation pause and
405 // retry the allocation.
406 //
407 // * If all allocation attempts fail, even after trying to schedule
408 // an evacuation pause, allocate_new_tlab() will return NULL,
409 // whereas mem_allocate() will attempt a heap expansion and/or
410 // schedule a Full GC.
411 //
412 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
413 // should never be called with word_size being humongous. All
414 // humongous allocation requests should go to mem_allocate() which
415 // will satisfy them with a special path.
416
417 virtual HeapWord* allocate_new_tlab(size_t min_size,
418 size_t requested_size,
419 size_t* actual_size);
420
421 virtual HeapWord* mem_allocate(size_t word_size,
422 bool* gc_overhead_limit_was_exceeded);
423
424 // First-level mutator allocation attempt: try to allocate out of
425 // the mutator alloc region without taking the Heap_lock. This
426 // should only be used for non-humongous allocations.
427 inline HeapWord* attempt_allocation(size_t min_word_size,
428 size_t desired_word_size,
429 size_t* actual_word_size);
430
431 // Second-level mutator allocation attempt: take the Heap_lock and
432 // retry the allocation attempt, potentially scheduling a GC
433 // pause. This should only be used for non-humongous allocations.
434 HeapWord* attempt_allocation_slow(size_t word_size);
435
436 // Takes the Heap_lock and attempts a humongous allocation. It can
437 // potentially schedule a GC pause.
438 HeapWord* attempt_allocation_humongous(size_t word_size);
439
440 // Allocation attempt that should be called during safepoints (e.g.,
441 // at the end of a successful GC). expect_null_mutator_alloc_region
442 // specifies whether the mutator alloc region is expected to be NULL
443 // or not.
444 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
445 bool expect_null_mutator_alloc_region);
446
447 // These methods are the "callbacks" from the G1AllocRegion class.
448
449 // For mutator alloc regions.
450 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
451 void retire_mutator_alloc_region(HeapRegion* alloc_region,
452 size_t allocated_bytes);
453
454 // For GC alloc regions.
455 bool has_more_regions(InCSetState dest);
456 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
457 void retire_gc_alloc_region(HeapRegion* alloc_region,
458 size_t allocated_bytes, InCSetState dest);
459
460 // - if explicit_gc is true, the GC is for a System.gc() etc,
461 // otherwise it's for a failed allocation.
462 // - if clear_all_soft_refs is true, all soft references should be
463 // cleared during the GC.
464 // - it returns false if it is unable to do the collection due to the
465 // GC locker being active, true otherwise.
466 bool do_full_collection(bool explicit_gc,
467 bool clear_all_soft_refs);
468
469 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
470 virtual void do_full_collection(bool clear_all_soft_refs);
471
472 // Callback from VM_G1CollectForAllocation operation.
473 // This function does everything necessary/possible to satisfy a
474 // failed allocation request (including collection, expansion, etc.)
475 HeapWord* satisfy_failed_allocation(size_t word_size,
476 bool* succeeded);
477 // Internal helpers used during full GC to split it up to
478 // increase readability.
479 void abort_concurrent_cycle();
480 void verify_before_full_collection(bool explicit_gc);
481 void prepare_heap_for_full_collection();
482 void prepare_heap_for_mutators();
483 void abort_refinement();
484 void verify_after_full_collection();
485 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
486
487 // Helper method for satisfy_failed_allocation()
488 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
489 bool do_gc,
490 bool clear_all_soft_refs,
491 bool expect_null_mutator_alloc_region,
492 bool* gc_succeeded);
493
494 // Attempting to expand the heap sufficiently
495 // to support an allocation of the given "word_size". If
496 // successful, perform the allocation and return the address of the
497 // allocated block, or else "NULL".
498 HeapWord* expand_and_allocate(size_t word_size);
499
500 // Process any reference objects discovered.
501 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
502
503 // If during an initial mark pause we may install a pending list head which is not
504 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
505 // to discover.
506 void make_pending_list_reachable();
507
508 // Merges the information gathered on a per-thread basis for all worker threads
509 // during GC into global variables.
510 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
511 public:
512 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; }
513
514 WorkGang* workers() const { return _workers; }
515
516 G1Allocator* allocator() {
517 return _allocator;
518 }
519
520 G1HeapVerifier* verifier() {
521 return _verifier;
522 }
523
524 G1MonitoringSupport* g1mm() {
525 assert(_g1mm != NULL, "should have been initialized");
526 return _g1mm;
527 }
528
529 void resize_heap_if_necessary();
530
531 // Expand the garbage-first heap by at least the given size (in bytes!).
532 // Returns true if the heap was expanded by the requested amount;
533 // false otherwise.
534 // (Rounds up to a HeapRegion boundary.)
535 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
536
537 // Returns the PLAB statistics for a given destination.
538 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
539
540 // Determines PLAB size for a given destination.
541 inline size_t desired_plab_sz(InCSetState dest);
542
543 // Do anything common to GC's.
544 void gc_prologue(bool full);
545 void gc_epilogue(bool full);
546
547 // Does the given region fulfill remembered set based eager reclaim candidate requirements?
548 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const;
549
550 // Modify the reclaim candidate set and test for presence.
551 // These are only valid for starts_humongous regions.
552 inline void set_humongous_reclaim_candidate(uint region, bool value);
553 inline bool is_humongous_reclaim_candidate(uint region);
554
555 // Remove from the reclaim candidate set. Also remove from the
556 // collection set so that later encounters avoid the slow path.
557 inline void set_humongous_is_live(oop obj);
558
559 // Register the given region to be part of the collection set.
560 inline void register_humongous_region_with_cset(uint index);
561 // Register regions with humongous objects (actually on the start region) in
562 // the in_cset_fast_test table.
563 void register_humongous_regions_with_cset();
564 // We register a region with the fast "in collection set" test. We
565 // simply set to true the array slot corresponding to this region.
566 void register_young_region_with_cset(HeapRegion* r) {
567 _in_cset_fast_test.set_in_young(r->hrm_index());
568 }
569 void register_old_region_with_cset(HeapRegion* r) {
570 _in_cset_fast_test.set_in_old(r->hrm_index());
571 }
572 void register_optional_region_with_cset(HeapRegion* r) {
573 _in_cset_fast_test.set_optional(r->hrm_index());
574 }
575 void clear_in_cset(const HeapRegion* hr) {
576 _in_cset_fast_test.clear(hr);
577 }
578
579 void clear_cset_fast_test() {
580 _in_cset_fast_test.clear();
581 }
582
583 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
584
585 // This is called at the start of either a concurrent cycle or a Full
586 // GC to update the number of old marking cycles started.
587 void increment_old_marking_cycles_started();
588
589 // This is called at the end of either a concurrent cycle or a Full
590 // GC to update the number of old marking cycles completed. Those two
591 // can happen in a nested fashion, i.e., we start a concurrent
592 // cycle, a Full GC happens half-way through it which ends first,
593 // and then the cycle notices that a Full GC happened and ends
594 // too. The concurrent parameter is a boolean to help us do a bit
595 // tighter consistency checking in the method. If concurrent is
596 // false, the caller is the inner caller in the nesting (i.e., the
597 // Full GC). If concurrent is true, the caller is the outer caller
598 // in this nesting (i.e., the concurrent cycle). Further nesting is
599 // not currently supported. The end of this call also notifies
600 // the FullGCCount_lock in case a Java thread is waiting for a full
601 // GC to happen (e.g., it called System.gc() with
602 // +ExplicitGCInvokesConcurrent).
603 void increment_old_marking_cycles_completed(bool concurrent);
604
605 uint old_marking_cycles_completed() {
606 return _old_marking_cycles_completed;
607 }
608
609 G1HRPrinter* hr_printer() { return &_hr_printer; }
610
611 // Allocates a new heap region instance.
612 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
613
614 // Allocate the highest free region in the reserved heap. This will commit
615 // regions as necessary.
616 HeapRegion* alloc_highest_free_region();
617
618 // Frees a non-humongous region by initializing its contents and
619 // adding it to the free list that's passed as a parameter (this is
620 // usually a local list which will be appended to the master free
621 // list later). The used bytes of freed regions are accumulated in
622 // pre_used. If skip_remset is true, the region's RSet will not be freed
623 // up. If skip_hot_card_cache is true, the region's hot card cache will not
624 // be freed up. The assumption is that this will be done later.
625 // The locked parameter indicates if the caller has already taken
626 // care of proper synchronization. This may allow some optimizations.
627 void free_region(HeapRegion* hr,
628 FreeRegionList* free_list,
629 bool skip_remset,
630 bool skip_hot_card_cache = false,
631 bool locked = false);
632
633 // It dirties the cards that cover the block so that the post
634 // write barrier never queues anything when updating objects on this
635 // block. It is assumed (and in fact we assert) that the block
636 // belongs to a young region.
637 inline void dirty_young_block(HeapWord* start, size_t word_size);
638
639 // Frees a humongous region by collapsing it into individual regions
640 // and calling free_region() for each of them. The freed regions
641 // will be added to the free list that's passed as a parameter (this
642 // is usually a local list which will be appended to the master free
643 // list later).
644 // The method assumes that only a single thread is ever calling
645 // this for a particular region at once.
646 void free_humongous_region(HeapRegion* hr,
647 FreeRegionList* free_list);
648
649 // Facility for allocating in 'archive' regions in high heap memory and
650 // recording the allocated ranges. These should all be called from the
651 // VM thread at safepoints, without the heap lock held. They can be used
652 // to create and archive a set of heap regions which can be mapped at the
653 // same fixed addresses in a subsequent JVM invocation.
654 void begin_archive_alloc_range(bool open = false);
655
656 // Check if the requested size would be too large for an archive allocation.
657 bool is_archive_alloc_too_large(size_t word_size);
658
659 // Allocate memory of the requested size from the archive region. This will
660 // return NULL if the size is too large or if no memory is available. It
661 // does not trigger a garbage collection.
662 HeapWord* archive_mem_allocate(size_t word_size);
663
664 // Optionally aligns the end address and returns the allocated ranges in
665 // an array of MemRegions in order of ascending addresses.
666 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
667 size_t end_alignment_in_bytes = 0);
668
669 // Facility for allocating a fixed range within the heap and marking
670 // the containing regions as 'archive'. For use at JVM init time, when the
671 // caller may mmap archived heap data at the specified range(s).
672 // Verify that the MemRegions specified in the argument array are within the
673 // reserved heap.
674 bool check_archive_addresses(MemRegion* range, size_t count);
675
676 // Commit the appropriate G1 regions containing the specified MemRegions
677 // and mark them as 'archive' regions. The regions in the array must be
678 // non-overlapping and in order of ascending address.
679 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
680
681 // Insert any required filler objects in the G1 regions around the specified
682 // ranges to make the regions parseable. This must be called after
683 // alloc_archive_regions, and after class loading has occurred.
684 void fill_archive_regions(MemRegion* range, size_t count);
685
686 // For each of the specified MemRegions, uncommit the containing G1 regions
687 // which had been allocated by alloc_archive_regions. This should be called
688 // rather than fill_archive_regions at JVM init time if the archive file
689 // mapping failed, with the same non-overlapping and sorted MemRegion array.
690 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open);
691
692 oop materialize_archived_object(oop obj);
693
694 private:
695
696 // Shrink the garbage-first heap by at most the given size (in bytes!).
697 // (Rounds down to a HeapRegion boundary.)
698 void shrink(size_t expand_bytes);
699 void shrink_helper(size_t expand_bytes);
700
701 #if TASKQUEUE_STATS
702 static void print_taskqueue_stats_hdr(outputStream* const st);
703 void print_taskqueue_stats() const;
704 void reset_taskqueue_stats();
705 #endif // TASKQUEUE_STATS
706
707 // Schedule the VM operation that will do an evacuation pause to
708 // satisfy an allocation request of word_size. *succeeded will
709 // return whether the VM operation was successful (it did do an
710 // evacuation pause) or not (another thread beat us to it or the GC
711 // locker was active). Given that we should not be holding the
712 // Heap_lock when we enter this method, we will pass the
713 // gc_count_before (i.e., total_collections()) as a parameter since
714 // it has to be read while holding the Heap_lock. Currently, both
715 // methods that call do_collection_pause() release the Heap_lock
716 // before the call, so it's easy to read gc_count_before just before.
717 HeapWord* do_collection_pause(size_t word_size,
718 uint gc_count_before,
719 bool* succeeded,
720 GCCause::Cause gc_cause);
721
722 void wait_for_root_region_scanning();
723
724 // The guts of the incremental collection pause, executed by the vm
725 // thread. It returns false if it is unable to do the collection due
726 // to the GC locker being active, true otherwise
727 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
728
729 // Actually do the work of evacuating the collection set.
730 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states);
731 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states);
732 void evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset);
733
734 void pre_evacuate_collection_set();
735 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
736
737 // Print the header for the per-thread termination statistics.
738 static void print_termination_stats_hdr();
739 // Print actual per-thread termination statistics.
740 void print_termination_stats(uint worker_id,
741 double elapsed_ms,
742 double strong_roots_ms,
743 double term_ms,
744 size_t term_attempts,
745 size_t alloc_buffer_waste,
746 size_t undo_waste) const;
747 // Update object copying statistics.
748 void record_obj_copy_mem_stats();
749
750 // The hot card cache for remembered set insertion optimization.
751 G1HotCardCache* _hot_card_cache;
752
753 // The g1 remembered set of the heap.
754 G1RemSet* _g1_rem_set;
755
756 // A set of cards that cover the objects for which the Rsets should be updated
757 // concurrently after the collection.
758 DirtyCardQueueSet _dirty_card_queue_set;
759
760 // After a collection pause, convert the regions in the collection set into free
761 // regions.
762 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
763
764 // Abandon the current collection set without recording policy
765 // statistics or updating free lists.
766 void abandon_collection_set(G1CollectionSet* collection_set);
767
768 // The concurrent marker (and the thread it runs in.)
769 G1ConcurrentMark* _cm;
770 G1ConcurrentMarkThread* _cm_thread;
771
772 // The concurrent refiner.
773 G1ConcurrentRefine* _cr;
774
775 // The parallel task queues
776 RefToScanQueueSet *_task_queues;
777
778 // True iff a evacuation has failed in the current collection.
779 bool _evacuation_failed;
780
781 EvacuationFailedInfo* _evacuation_failed_info_array;
782
783 // Failed evacuations cause some logical from-space objects to have
784 // forwarding pointers to themselves. Reset them.
785 void remove_self_forwarding_pointers();
786
787 // Restore the objects in the regions in the collection set after an
788 // evacuation failure.
789 void restore_after_evac_failure();
790
791 PreservedMarksSet _preserved_marks_set;
792
793 // Preserve the mark of "obj", if necessary, in preparation for its mark
794 // word being overwritten with a self-forwarding-pointer.
795 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
796
797 #ifndef PRODUCT
798 // Support for forcing evacuation failures. Analogous to
799 // PromotionFailureALot for the other collectors.
800
801 // Records whether G1EvacuationFailureALot should be in effect
802 // for the current GC
803 bool _evacuation_failure_alot_for_current_gc;
804
805 // Used to record the GC number for interval checking when
806 // determining whether G1EvaucationFailureALot is in effect
807 // for the current GC.
808 size_t _evacuation_failure_alot_gc_number;
809
810 // Count of the number of evacuations between failures.
811 volatile size_t _evacuation_failure_alot_count;
812
813 // Set whether G1EvacuationFailureALot should be in effect
814 // for the current GC (based upon the type of GC and which
815 // command line flags are set);
816 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc,
817 bool during_initial_mark,
818 bool mark_or_rebuild_in_progress);
819
820 inline void set_evacuation_failure_alot_for_current_gc();
821
822 // Return true if it's time to cause an evacuation failure.
823 inline bool evacuation_should_fail();
824
825 // Reset the G1EvacuationFailureALot counters. Should be called at
826 // the end of an evacuation pause in which an evacuation failure occurred.
827 inline void reset_evacuation_should_fail();
828 #endif // !PRODUCT
829
830 // ("Weak") Reference processing support.
831 //
832 // G1 has 2 instances of the reference processor class. One
833 // (_ref_processor_cm) handles reference object discovery
834 // and subsequent processing during concurrent marking cycles.
835 //
836 // The other (_ref_processor_stw) handles reference object
837 // discovery and processing during full GCs and incremental
838 // evacuation pauses.
839 //
840 // During an incremental pause, reference discovery will be
841 // temporarily disabled for _ref_processor_cm and will be
842 // enabled for _ref_processor_stw. At the end of the evacuation
843 // pause references discovered by _ref_processor_stw will be
844 // processed and discovery will be disabled. The previous
845 // setting for reference object discovery for _ref_processor_cm
846 // will be re-instated.
847 //
848 // At the start of marking:
849 // * Discovery by the CM ref processor is verified to be inactive
850 // and it's discovered lists are empty.
851 // * Discovery by the CM ref processor is then enabled.
852 //
853 // At the end of marking:
854 // * Any references on the CM ref processor's discovered
855 // lists are processed (possibly MT).
856 //
857 // At the start of full GC we:
858 // * Disable discovery by the CM ref processor and
859 // empty CM ref processor's discovered lists
860 // (without processing any entries).
861 // * Verify that the STW ref processor is inactive and it's
862 // discovered lists are empty.
863 // * Temporarily set STW ref processor discovery as single threaded.
864 // * Temporarily clear the STW ref processor's _is_alive_non_header
865 // field.
866 // * Finally enable discovery by the STW ref processor.
867 //
868 // The STW ref processor is used to record any discovered
869 // references during the full GC.
870 //
871 // At the end of a full GC we:
872 // * Enqueue any reference objects discovered by the STW ref processor
873 // that have non-live referents. This has the side-effect of
874 // making the STW ref processor inactive by disabling discovery.
875 // * Verify that the CM ref processor is still inactive
876 // and no references have been placed on it's discovered
877 // lists (also checked as a precondition during initial marking).
878
879 // The (stw) reference processor...
880 ReferenceProcessor* _ref_processor_stw;
881
882 // During reference object discovery, the _is_alive_non_header
883 // closure (if non-null) is applied to the referent object to
884 // determine whether the referent is live. If so then the
885 // reference object does not need to be 'discovered' and can
886 // be treated as a regular oop. This has the benefit of reducing
887 // the number of 'discovered' reference objects that need to
888 // be processed.
889 //
890 // Instance of the is_alive closure for embedding into the
891 // STW reference processor as the _is_alive_non_header field.
892 // Supplying a value for the _is_alive_non_header field is
893 // optional but doing so prevents unnecessary additions to
894 // the discovered lists during reference discovery.
895 G1STWIsAliveClosure _is_alive_closure_stw;
896
897 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw;
898
899 // The (concurrent marking) reference processor...
900 ReferenceProcessor* _ref_processor_cm;
901
902 // Instance of the concurrent mark is_alive closure for embedding
903 // into the Concurrent Marking reference processor as the
904 // _is_alive_non_header field. Supplying a value for the
905 // _is_alive_non_header field is optional but doing so prevents
906 // unnecessary additions to the discovered lists during reference
907 // discovery.
908 G1CMIsAliveClosure _is_alive_closure_cm;
909
910 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm;
911 public:
912
913 RefToScanQueue *task_queue(uint i) const;
914
915 uint num_task_queues() const;
916
917 // A set of cards where updates happened during the GC
918 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
919
920 // Create a G1CollectedHeap with the specified policy.
921 // Must call the initialize method afterwards.
922 // May not return if something goes wrong.
923 G1CollectedHeap(G1CollectorPolicy* policy);
924
925 private:
926 jint initialize_concurrent_refinement();
927 jint initialize_young_gen_sampling_thread();
928 public:
929 // Initialize the G1CollectedHeap to have the initial and
930 // maximum sizes and remembered and barrier sets
931 // specified by the policy object.
932 jint initialize();
933
934 virtual void stop();
935 virtual void safepoint_synchronize_begin();
936 virtual void safepoint_synchronize_end();
937
938 // Return the (conservative) maximum heap alignment for any G1 heap
939 static size_t conservative_max_heap_alignment();
940
941 // Does operations required after initialization has been done.
942 void post_initialize();
943
944 // Initialize weak reference processing.
945 void ref_processing_init();
946
947 virtual Name kind() const {
948 return CollectedHeap::G1;
949 }
950
951 virtual const char* name() const {
952 return "G1";
953 }
954
955 const G1CollectorState* collector_state() const { return &_collector_state; }
956 G1CollectorState* collector_state() { return &_collector_state; }
957
958 // The current policy object for the collector.
959 G1Policy* g1_policy() const { return _g1_policy; }
960
961 const G1CollectionSet* collection_set() const { return &_collection_set; }
962 G1CollectionSet* collection_set() { return &_collection_set; }
963
964 virtual CollectorPolicy* collector_policy() const;
965
966 virtual SoftRefPolicy* soft_ref_policy();
967
968 virtual void initialize_serviceability();
969 virtual MemoryUsage memory_usage();
970 virtual GrowableArray<GCMemoryManager*> memory_managers();
971 virtual GrowableArray<MemoryPool*> memory_pools();
972
973 // The rem set and barrier set.
974 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
975
976 // Try to minimize the remembered set.
977 void scrub_rem_set();
978
979 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
980 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
981
982 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
983 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
984
985 // The shared block offset table array.
986 G1BlockOffsetTable* bot() const { return _bot; }
987
988 // Reference Processing accessors
989
990 // The STW reference processor....
991 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
992
993 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
994
995 // The Concurrent Marking reference processor...
996 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
997
998 size_t unused_committed_regions_in_bytes() const;
999 virtual size_t capacity() const;
1000 virtual size_t used() const;
1001 // This should be called when we're not holding the heap lock. The
1002 // result might be a bit inaccurate.
1003 size_t used_unlocked() const;
1004 size_t recalculate_used() const;
1005
1006 // These virtual functions do the actual allocation.
1007 // Some heaps may offer a contiguous region for shared non-blocking
1008 // allocation, via inlined code (by exporting the address of the top and
1009 // end fields defining the extent of the contiguous allocation region.)
1010 // But G1CollectedHeap doesn't yet support this.
1011
1012 virtual bool is_maximal_no_gc() const {
1013 return _hrm.available() == 0;
1014 }
1015
1016 // Returns whether there are any regions left in the heap for allocation.
1017 bool has_regions_left_for_allocation() const {
1018 return !is_maximal_no_gc() || num_free_regions() != 0;
1019 }
1020
1021 // The current number of regions in the heap.
1022 uint num_regions() const { return _hrm.length(); }
1023
1024 // The max number of regions in the heap.
1025 uint max_regions() const { return _hrm.max_length(); }
1026
1027 // The number of regions that are completely free.
1028 uint num_free_regions() const { return _hrm.num_free_regions(); }
1029
1030 MemoryUsage get_auxiliary_data_memory_usage() const {
1031 return _hrm.get_auxiliary_data_memory_usage();
1032 }
1033
1034 // The number of regions that are not completely free.
1035 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1036
1037 #ifdef ASSERT
1038 bool is_on_master_free_list(HeapRegion* hr) {
1039 return _hrm.is_free(hr);
1040 }
1041 #endif // ASSERT
1042
1043 inline void old_set_add(HeapRegion* hr);
1044 inline void old_set_remove(HeapRegion* hr);
1045
1046 inline void archive_set_add(HeapRegion* hr);
1047
1048 size_t non_young_capacity_bytes() {
1049 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes;
1050 }
1051
1052 // Determine whether the given region is one that we are using as an
1053 // old GC alloc region.
1054 bool is_old_gc_alloc_region(HeapRegion* hr);
1055
1056 // Perform a collection of the heap; intended for use in implementing
1057 // "System.gc". This probably implies as full a collection as the
1058 // "CollectedHeap" supports.
1059 virtual void collect(GCCause::Cause cause);
1060
1061 // True iff an evacuation has failed in the most-recent collection.
1062 bool evacuation_failed() { return _evacuation_failed; }
1063
1064 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1065 void prepend_to_freelist(FreeRegionList* list);
1066 void decrement_summary_bytes(size_t bytes);
1067
1068 virtual bool is_in(const void* p) const;
1069 #ifdef ASSERT
1070 // Returns whether p is in one of the available areas of the heap. Slow but
1071 // extensive version.
1072 bool is_in_exact(const void* p) const;
1073 #endif
1074
1075 // Return "TRUE" iff the given object address is within the collection
1076 // set. Assumes that the reference points into the heap.
1077 inline bool is_in_cset(const HeapRegion *hr);
1078 inline bool is_in_cset(oop obj);
1079 inline bool is_in_cset(HeapWord* addr);
1080
1081 inline bool is_in_cset_or_humongous(const oop obj);
1082
1083 private:
1084 // This array is used for a quick test on whether a reference points into
1085 // the collection set or not. Each of the array's elements denotes whether the
1086 // corresponding region is in the collection set or not.
1087 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1088
1089 public:
1090
1091 inline InCSetState in_cset_state(const oop obj);
1092
1093 // Return "TRUE" iff the given object address is in the reserved
1094 // region of g1.
1095 bool is_in_g1_reserved(const void* p) const {
1096 return _hrm.reserved().contains(p);
1097 }
1098
1099 // Returns a MemRegion that corresponds to the space that has been
1100 // reserved for the heap
1101 MemRegion g1_reserved() const {
1102 return _hrm.reserved();
1103 }
1104
1105 virtual bool is_in_closed_subset(const void* p) const;
1106
1107 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; }
1108
1109 G1CardTable* card_table() const {
1110 return _card_table;
1111 }
1112
1113 // Iteration functions.
1114
1115 // Iterate over all objects, calling "cl.do_object" on each.
1116 virtual void object_iterate(ObjectClosure* cl);
1117
1118 virtual void safe_object_iterate(ObjectClosure* cl) {
1119 object_iterate(cl);
1120 }
1121
1122 // Iterate over heap regions, in address order, terminating the
1123 // iteration early if the "do_heap_region" method returns "true".
1124 void heap_region_iterate(HeapRegionClosure* blk) const;
1125
1126 // Return the region with the given index. It assumes the index is valid.
1127 inline HeapRegion* region_at(uint index) const;
1128 inline HeapRegion* region_at_or_null(uint index) const;
1129
1130 // Return the next region (by index) that is part of the same
1131 // humongous object that hr is part of.
1132 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1133
1134 // Calculate the region index of the given address. Given address must be
1135 // within the heap.
1136 inline uint addr_to_region(HeapWord* addr) const;
1137
1138 inline HeapWord* bottom_addr_for_region(uint index) const;
1139
1140 // Two functions to iterate over the heap regions in parallel. Threads
1141 // compete using the HeapRegionClaimer to claim the regions before
1142 // applying the closure on them.
1143 // The _from_worker_offset version uses the HeapRegionClaimer and
1144 // the worker id to calculate a start offset to prevent all workers to
1145 // start from the point.
1146 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
1147 HeapRegionClaimer* hrclaimer,
1148 uint worker_id) const;
1149
1150 void heap_region_par_iterate_from_start(HeapRegionClosure* cl,
1151 HeapRegionClaimer* hrclaimer) const;
1152
1153 // Iterate over the regions (if any) in the current collection set.
1154 void collection_set_iterate(HeapRegionClosure* blk);
1155
1156 // Iterate over the regions (if any) in the current collection set. Starts the
1157 // iteration over the entire collection set so that the start regions of a given
1158 // worker id over the set active_workers are evenly spread across the set of
1159 // collection set regions.
1160 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1161
1162 // Returns the HeapRegion that contains addr. addr must not be NULL.
1163 template <class T>
1164 inline HeapRegion* heap_region_containing(const T addr) const;
1165
1166 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted
1167 // region. addr must not be NULL.
1168 template <class T>
1169 inline HeapRegion* heap_region_containing_or_null(const T addr) const;
1170
1171 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1172 // each address in the (reserved) heap is a member of exactly
1173 // one block. The defining characteristic of a block is that it is
1174 // possible to find its size, and thus to progress forward to the next
1175 // block. (Blocks may be of different sizes.) Thus, blocks may
1176 // represent Java objects, or they might be free blocks in a
1177 // free-list-based heap (or subheap), as long as the two kinds are
1178 // distinguishable and the size of each is determinable.
1179
1180 // Returns the address of the start of the "block" that contains the
1181 // address "addr". We say "blocks" instead of "object" since some heaps
1182 // may not pack objects densely; a chunk may either be an object or a
1183 // non-object.
1184 virtual HeapWord* block_start(const void* addr) const;
1185
1186 // Requires "addr" to be the start of a chunk, and returns its size.
1187 // "addr + size" is required to be the start of a new chunk, or the end
1188 // of the active area of the heap.
1189 virtual size_t block_size(const HeapWord* addr) const;
1190
1191 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1192 // the block is an object.
1193 virtual bool block_is_obj(const HeapWord* addr) const;
1194
1195 // Section on thread-local allocation buffers (TLABs)
1196 // See CollectedHeap for semantics.
1197
1198 bool supports_tlab_allocation() const;
1199 size_t tlab_capacity(Thread* ignored) const;
1200 size_t tlab_used(Thread* ignored) const;
1201 size_t max_tlab_size() const;
1202 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1203
1204 inline bool is_in_young(const oop obj);
1205
1206 // Returns "true" iff the given word_size is "very large".
1207 static bool is_humongous(size_t word_size) {
1208 // Note this has to be strictly greater-than as the TLABs
1209 // are capped at the humongous threshold and we want to
1210 // ensure that we don't try to allocate a TLAB as
1211 // humongous and that we don't allocate a humongous
1212 // object in a TLAB.
1213 return word_size > _humongous_object_threshold_in_words;
1214 }
1215
1216 // Returns the humongous threshold for a specific region size
1217 static size_t humongous_threshold_for(size_t region_size) {
1218 return (region_size / 2);
1219 }
1220
1221 // Returns the number of regions the humongous object of the given word size
1222 // requires.
1223 static size_t humongous_obj_size_in_regions(size_t word_size);
1224
1225 // Print the maximum heap capacity.
1226 virtual size_t max_capacity() const;
1227
1228 virtual jlong millis_since_last_gc();
1229
1230
1231 // Convenience function to be used in situations where the heap type can be
1232 // asserted to be this type.
1233 static G1CollectedHeap* heap();
1234
1235 void set_region_short_lived_locked(HeapRegion* hr);
1236 // add appropriate methods for any other surv rate groups
1237
1238 const G1SurvivorRegions* survivor() const { return &_survivor; }
1239
1240 uint eden_regions_count() const { return _eden.length(); }
1241 uint survivor_regions_count() const { return _survivor.length(); }
1242 uint young_regions_count() const { return _eden.length() + _survivor.length(); }
1243 uint old_regions_count() const { return _old_set.length(); }
1244 uint archive_regions_count() const { return _archive_set.length(); }
1245 uint humongous_regions_count() const { return _humongous_set.length(); }
1246
1247 #ifdef ASSERT
1248 bool check_young_list_empty();
1249 #endif
1250
1251 // *** Stuff related to concurrent marking. It's not clear to me that so
1252 // many of these need to be public.
1253
1254 // The functions below are helper functions that a subclass of
1255 // "CollectedHeap" can use in the implementation of its virtual
1256 // functions.
1257 // This performs a concurrent marking of the live objects in a
1258 // bitmap off to the side.
1259 void do_concurrent_mark();
1260
1261 bool is_marked_next(oop obj) const;
1262
1263 // Determine if an object is dead, given the object and also
1264 // the region to which the object belongs. An object is dead
1265 // iff a) it was not allocated since the last mark, b) it
1266 // is not marked, and c) it is not in an archive region.
1267 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1268 return
1269 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) &&
1270 !hr->is_archive();
1271 }
1272
1273 // This function returns true when an object has been
1274 // around since the previous marking and hasn't yet
1275 // been marked during this marking, and is not in an archive region.
1276 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1277 return
1278 !hr->obj_allocated_since_next_marking(obj) &&
1279 !is_marked_next(obj) &&
1280 !hr->is_archive();
1281 }
1282
1283 // Determine if an object is dead, given only the object itself.
1284 // This will find the region to which the object belongs and
1285 // then call the region version of the same function.
1286
1287 // Added if it is NULL it isn't dead.
1288
1289 inline bool is_obj_dead(const oop obj) const;
1290
1291 inline bool is_obj_ill(const oop obj) const;
1292
1293 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const;
1294 inline bool is_obj_dead_full(const oop obj) const;
1295
1296 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1297
1298 // Refinement
1299
1300 G1ConcurrentRefine* concurrent_refine() const { return _cr; }
1301
1302 // Optimized nmethod scanning support routines
1303
1304 // Is an oop scavengeable
1305 virtual bool is_scavengable(oop obj);
1306
1307 // Register the given nmethod with the G1 heap.
1308 virtual void register_nmethod(nmethod* nm);
1309
1310 // Unregister the given nmethod from the G1 heap.
1311 virtual void unregister_nmethod(nmethod* nm);
1312
1313 // Free up superfluous code root memory.
1314 void purge_code_root_memory();
1315
1316 // Rebuild the strong code root lists for each region
1317 // after a full GC.
1318 void rebuild_strong_code_roots();
1319
1320 // Partial cleaning used when class unloading is disabled.
1321 // Let the caller choose what structures to clean out:
1322 // - StringTable
1323 // - StringDeduplication structures
1324 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_string_dedup);
1325
1326 // Complete cleaning used when class unloading is enabled.
1327 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1328 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1329
1330 // Redirty logged cards in the refinement queue.
1331 void redirty_logged_cards();
1332 // Verification
1333
1334 // Deduplicate the string
1335 virtual void deduplicate_string(oop str);
1336
1337 // Perform any cleanup actions necessary before allowing a verification.
1338 virtual void prepare_for_verify();
1339
1340 // Perform verification.
1341
1342 // vo == UsePrevMarking -> use "prev" marking information,
1343 // vo == UseNextMarking -> use "next" marking information
1344 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS
1345 //
1346 // NOTE: Only the "prev" marking information is guaranteed to be
1347 // consistent most of the time, so most calls to this should use
1348 // vo == UsePrevMarking.
1349 // Currently, there is only one case where this is called with
1350 // vo == UseNextMarking, which is to verify the "next" marking
1351 // information at the end of remark.
1352 // Currently there is only one place where this is called with
1353 // vo == UseFullMarking, which is to verify the marking during a
1354 // full GC.
1355 void verify(VerifyOption vo);
1356
1357 // WhiteBox testing support.
1358 virtual bool supports_concurrent_phase_control() const;
1359 virtual const char* const* concurrent_phases() const;
1360 virtual bool request_concurrent_phase(const char* phase);
1361
1362 virtual WorkGang* get_safepoint_workers() { return _workers; }
1363
1364 // The methods below are here for convenience and dispatch the
1365 // appropriate method depending on value of the given VerifyOption
1366 // parameter. The values for that parameter, and their meanings,
1367 // are the same as those above.
1368
1369 bool is_obj_dead_cond(const oop obj,
1370 const HeapRegion* hr,
1371 const VerifyOption vo) const;
1372
1373 bool is_obj_dead_cond(const oop obj,
1374 const VerifyOption vo) const;
1375
1376 G1HeapSummary create_g1_heap_summary();
1377 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1378
1379 // Printing
1380 private:
1381 void print_heap_regions() const;
1382 void print_regions_on(outputStream* st) const;
1383
1384 public:
1385 virtual void print_on(outputStream* st) const;
1386 virtual void print_extended_on(outputStream* st) const;
1387 virtual void print_on_error(outputStream* st) const;
1388
1389 virtual void print_gc_threads_on(outputStream* st) const;
1390 virtual void gc_threads_do(ThreadClosure* tc) const;
1391
1392 // Override
1393 void print_tracing_info() const;
1394
1395 // The following two methods are helpful for debugging RSet issues.
1396 void print_cset_rsets() PRODUCT_RETURN;
1397 void print_all_rsets() PRODUCT_RETURN;
1398
1399 size_t pending_card_num();
1400 };
1401
1402 class G1ParEvacuateFollowersClosure : public VoidClosure {
1403 private:
1404 double _start_term;
1405 double _term_time;
1406 size_t _term_attempts;
1407
1408 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1409 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1410 protected:
1411 G1CollectedHeap* _g1h;
1412 G1ParScanThreadState* _par_scan_state;
1413 RefToScanQueueSet* _queues;
1414 ParallelTaskTerminator* _terminator;
1415 G1GCPhaseTimes::GCParPhases _phase;
1416
1417 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1418 RefToScanQueueSet* queues() { return _queues; }
1419 ParallelTaskTerminator* terminator() { return _terminator; }
1420
1421 public:
1422 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1423 G1ParScanThreadState* par_scan_state,
1424 RefToScanQueueSet* queues,
1425 ParallelTaskTerminator* terminator,
1426 G1GCPhaseTimes::GCParPhases phase)
1427 : _start_term(0.0), _term_time(0.0), _term_attempts(0),
1428 _g1h(g1h), _par_scan_state(par_scan_state),
1429 _queues(queues), _terminator(terminator), _phase(phase) {}
1430
1431 void do_void();
1432
1433 double term_time() const { return _term_time; }
1434 size_t term_attempts() const { return _term_attempts; }
1435
1436 private:
1437 inline bool offer_termination();
1438 };
1439
1440 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP