1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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/g1AllocationContext.hpp"
30 #include "gc/g1/g1BiasedArray.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/g1HeapVerifier.hpp"
38 #include "gc/g1/g1HRPrinter.hpp"
39 #include "gc/g1/g1InCSetState.hpp"
40 #include "gc/g1/g1MonitoringSupport.hpp"
41 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
42 #include "gc/g1/g1SurvivorRegions.hpp"
43 #include "gc/g1/g1YCTypes.hpp"
44 #include "gc/g1/hSpaceCounters.hpp"
45 #include "gc/g1/heapRegionManager.hpp"
46 #include "gc/g1/heapRegionSet.hpp"
47 #include "gc/shared/barrierSet.hpp"
48 #include "gc/shared/collectedHeap.hpp"
49 #include "gc/shared/plab.hpp"
50 #include "gc/shared/preservedMarks.hpp"
51 #include "memory/memRegion.hpp"
52 #include "utilities/stack.hpp"
53
54 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
55 // It uses the "Garbage First" heap organization and algorithm, which
56 // may combine concurrent marking with parallel, incremental compaction of
57 // heap subsets that will yield large amounts of garbage.
58
59 // Forward declarations
60 class HeapRegion;
61 class HRRSCleanupTask;
62 class GenerationSpec;
63 class OopsInHeapRegionClosure;
64 class G1ParScanThreadState;
65 class G1ParScanThreadStateSet;
66 class G1KlassScanClosure;
67 class G1ParScanThreadState;
68 class ObjectClosure;
69 class SpaceClosure;
70 class CompactibleSpaceClosure;
71 class Space;
72 class G1CollectionSet;
73 class G1CollectorPolicy;
74 class G1Policy;
75 class G1HotCardCache;
76 class G1RemSet;
77 class HeapRegionRemSetIterator;
78 class G1ConcurrentMark;
79 class ConcurrentMarkThread;
80 class ConcurrentG1Refine;
81 class GenerationCounters;
82 class STWGCTimer;
83 class G1NewTracer;
84 class EvacuationFailedInfo;
85 class nmethod;
86 class Ticks;
87 class WorkGang;
88 class G1Allocator;
89 class G1ArchiveAllocator;
90 class G1HeapVerifier;
91 class G1HeapSizingPolicy;
92
93 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
94 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
95
96 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
97 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
98
99 // The G1 STW is alive closure.
100 // An instance is embedded into the G1CH and used as the
101 // (optional) _is_alive_non_header closure in the STW
102 // reference processor. It is also extensively used during
103 // reference processing during STW evacuation pauses.
104 class G1STWIsAliveClosure: public BoolObjectClosure {
105 G1CollectedHeap* _g1;
106 public:
107 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
108 bool do_object_b(oop p);
109 };
110
111 class RefineCardTableEntryClosure;
112
113 class G1RegionMappingChangedListener : public G1MappingChangedListener {
114 private:
115 void reset_from_card_cache(uint start_idx, size_t num_regions);
116 public:
117 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
118 };
119
120 class G1CollectedHeap : public CollectedHeap {
121 friend class G1FreeCollectionSetTask;
122 friend class VM_CollectForMetadataAllocation;
123 friend class VM_G1CollectForAllocation;
124 friend class VM_G1CollectFull;
125 friend class VM_G1IncCollectionPause;
126 friend class VMStructs;
127 friend class MutatorAllocRegion;
128 friend class G1GCAllocRegion;
129 friend class G1HeapVerifier;
130
131 // Closures used in implementation.
132 friend class G1ParScanThreadState;
133 friend class G1ParScanThreadStateSet;
134 friend class G1ParTask;
135 friend class G1PLABAllocator;
136 friend class G1PrepareCompactClosure;
137
138 // Other related classes.
139 friend class HeapRegionClaimer;
140
141 // Testing classes.
142 friend class G1CheckCSetFastTableClosure;
143
144 private:
145 WorkGang* _workers;
146 G1CollectorPolicy* _collector_policy;
147
148 static size_t _humongous_object_threshold_in_words;
149
150 // The secondary free list which contains regions that have been
151 // freed up during the cleanup process. This will be appended to
152 // the master free list when appropriate.
153 FreeRegionList _secondary_free_list;
154
155 // It keeps track of the old regions.
156 HeapRegionSet _old_set;
157
158 // It keeps track of the humongous regions.
159 HeapRegionSet _humongous_set;
160
161 void eagerly_reclaim_humongous_regions();
162 // Start a new incremental collection set for the next pause.
163 void start_new_collection_set();
164
165 // The number of regions we could create by expansion.
166 uint _expansion_regions;
167
168 // The block offset table for the G1 heap.
169 G1BlockOffsetTable* _bot;
170
171 // Tears down the region sets / lists so that they are empty and the
172 // regions on the heap do not belong to a region set / list. The
173 // only exception is the humongous set which we leave unaltered. If
174 // free_list_only is true, it will only tear down the master free
175 // list. It is called before a Full GC (free_list_only == false) or
176 // before heap shrinking (free_list_only == true).
177 void tear_down_region_sets(bool free_list_only);
178
179 // Rebuilds the region sets / lists so that they are repopulated to
180 // reflect the contents of the heap. The only exception is the
181 // humongous set which was not torn down in the first place. If
182 // free_list_only is true, it will only rebuild the master free
183 // list. It is called after a Full GC (free_list_only == false) or
184 // after heap shrinking (free_list_only == true).
185 void rebuild_region_sets(bool free_list_only);
186
187 // Callback for region mapping changed events.
188 G1RegionMappingChangedListener _listener;
189
190 // The sequence of all heap regions in the heap.
191 HeapRegionManager _hrm;
192
193 // Manages all allocations with regions except humongous object allocations.
194 G1Allocator* _allocator;
195
196 // Manages all heap verification.
197 G1HeapVerifier* _verifier;
198
199 // Outside of GC pauses, the number of bytes used in all regions other
200 // than the current allocation region(s).
201 size_t _summary_bytes_used;
202
203 void increase_used(size_t bytes);
204 void decrease_used(size_t bytes);
205
206 void set_used(size_t bytes);
207
208 // Class that handles archive allocation ranges.
209 G1ArchiveAllocator* _archive_allocator;
210
211 // Statistics for each allocation context
212 AllocationContextStats _allocation_context_stats;
213
214 // GC allocation statistics policy for survivors.
215 G1EvacStats _survivor_evac_stats;
216
217 // GC allocation statistics policy for tenured objects.
218 G1EvacStats _old_evac_stats;
219
220 // It specifies whether we should attempt to expand the heap after a
221 // region allocation failure. If heap expansion fails we set this to
222 // false so that we don't re-attempt the heap expansion (it's likely
223 // that subsequent expansion attempts will also fail if one fails).
224 // Currently, it is only consulted during GC and it's reset at the
225 // start of each GC.
226 bool _expand_heap_after_alloc_failure;
227
228 // Helper for monitoring and management support.
229 G1MonitoringSupport* _g1mm;
230
231 // Records whether the region at the given index is (still) a
232 // candidate for eager reclaim. Only valid for humongous start
233 // regions; other regions have unspecified values. Humongous start
234 // regions are initialized at start of collection pause, with
235 // candidates removed from the set as they are found reachable from
236 // roots or the young generation.
237 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
238 protected:
239 bool default_value() const { return false; }
240 public:
241 void clear() { G1BiasedMappedArray<bool>::clear(); }
242 void set_candidate(uint region, bool value) {
243 set_by_index(region, value);
244 }
245 bool is_candidate(uint region) {
246 return get_by_index(region);
247 }
248 };
249
250 HumongousReclaimCandidates _humongous_reclaim_candidates;
251 // Stores whether during humongous object registration we found candidate regions.
252 // If not, we can skip a few steps.
253 bool _has_humongous_reclaim_candidates;
254
255 volatile uint _gc_time_stamp;
256
257 G1HRPrinter _hr_printer;
258
259 // It decides whether an explicit GC should start a concurrent cycle
260 // instead of doing a STW GC. Currently, a concurrent cycle is
261 // explicitly started if:
262 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
263 // (b) cause == _g1_humongous_allocation
264 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
265 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
266 // (e) cause == _update_allocation_context_stats_inc
267 // (f) cause == _wb_conc_mark
268 bool should_do_concurrent_full_gc(GCCause::Cause cause);
269
270 // indicates whether we are in young or mixed GC mode
271 G1CollectorState _collector_state;
272
273 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
274 // concurrent cycles) we have started.
275 volatile uint _old_marking_cycles_started;
276
277 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
278 // concurrent cycles) we have completed.
279 volatile uint _old_marking_cycles_completed;
280
281 // This is a non-product method that is helpful for testing. It is
282 // called at the end of a GC and artificially expands the heap by
283 // allocating a number of dead regions. This way we can induce very
284 // frequent marking cycles and stress the cleanup / concurrent
285 // cleanup code more (as all the regions that will be allocated by
286 // this method will be found dead by the marking cycle).
287 void allocate_dummy_regions() PRODUCT_RETURN;
288
289 // Clear RSets after a compaction. It also resets the GC time stamps.
290 void clear_rsets_post_compaction();
291
292 // If the HR printer is active, dump the state of the regions in the
293 // heap after a compaction.
294 void print_hrm_post_compaction();
295
296 // Create a memory mapper for auxiliary data structures of the given size and
297 // translation factor.
298 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
299 size_t size,
300 size_t translation_factor);
301
302 static G1Policy* create_g1_policy();
303
304 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
305
306 void process_weak_jni_handles();
307
308 // These are macros so that, if the assert fires, we get the correct
309 // line number, file, etc.
310
311 #define heap_locking_asserts_params(_extra_message_) \
312 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
313 (_extra_message_), \
314 BOOL_TO_STR(Heap_lock->owned_by_self()), \
315 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
316 BOOL_TO_STR(Thread::current()->is_VM_thread())
317
318 #define assert_heap_locked() \
319 do { \
320 assert(Heap_lock->owned_by_self(), \
321 heap_locking_asserts_params("should be holding the Heap_lock")); \
322 } while (0)
323
324 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
325 do { \
326 assert(Heap_lock->owned_by_self() || \
327 (SafepointSynchronize::is_at_safepoint() && \
328 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
329 heap_locking_asserts_params("should be holding the Heap_lock or " \
330 "should be at a safepoint")); \
331 } while (0)
332
333 #define assert_heap_locked_and_not_at_safepoint() \
334 do { \
335 assert(Heap_lock->owned_by_self() && \
336 !SafepointSynchronize::is_at_safepoint(), \
337 heap_locking_asserts_params("should be holding the Heap_lock and " \
338 "should not be at a safepoint")); \
339 } while (0)
340
341 #define assert_heap_not_locked() \
342 do { \
343 assert(!Heap_lock->owned_by_self(), \
344 heap_locking_asserts_params("should not be holding the Heap_lock")); \
345 } while (0)
346
347 #define assert_heap_not_locked_and_not_at_safepoint() \
348 do { \
349 assert(!Heap_lock->owned_by_self() && \
350 !SafepointSynchronize::is_at_safepoint(), \
351 heap_locking_asserts_params("should not be holding the Heap_lock and " \
352 "should not be at a safepoint")); \
353 } while (0)
354
355 #define assert_at_safepoint(_should_be_vm_thread_) \
356 do { \
357 assert(SafepointSynchronize::is_at_safepoint() && \
358 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
359 heap_locking_asserts_params("should be at a safepoint")); \
360 } while (0)
361
362 #define assert_not_at_safepoint() \
363 do { \
364 assert(!SafepointSynchronize::is_at_safepoint(), \
365 heap_locking_asserts_params("should not be at a safepoint")); \
366 } while (0)
367
368 protected:
369
370 // The young region list.
371 G1EdenRegions _eden;
372 G1SurvivorRegions _survivor;
373
374 // The current policy object for the collector.
375 G1Policy* _g1_policy;
376 G1HeapSizingPolicy* _heap_sizing_policy;
377
378 G1CollectionSet _collection_set;
379
380 // This is the second level of trying to allocate a new region. If
381 // new_region() didn't find a region on the free_list, this call will
382 // check whether there's anything available on the
383 // secondary_free_list and/or wait for more regions to appear on
384 // that list, if _free_regions_coming is set.
385 HeapRegion* new_region_try_secondary_free_list(bool is_old);
386
387 // Try to allocate a single non-humongous HeapRegion sufficient for
388 // an allocation of the given word_size. If do_expand is true,
389 // attempt to expand the heap if necessary to satisfy the allocation
390 // request. If the region is to be used as an old region or for a
391 // humongous object, set is_old to true. If not, to false.
392 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
393
394 // Initialize a contiguous set of free regions of length num_regions
395 // and starting at index first so that they appear as a single
396 // humongous region.
397 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
398 uint num_regions,
399 size_t word_size,
400 AllocationContext_t context);
401
402 // Attempt to allocate a humongous object of the given size. Return
403 // NULL if unsuccessful.
404 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
405
406 // The following two methods, allocate_new_tlab() and
407 // mem_allocate(), are the two main entry points from the runtime
408 // into the G1's allocation routines. They have the following
409 // assumptions:
410 //
411 // * They should both be called outside safepoints.
412 //
413 // * They should both be called without holding the Heap_lock.
414 //
415 // * All allocation requests for new TLABs should go to
416 // allocate_new_tlab().
417 //
418 // * All non-TLAB allocation requests should go to mem_allocate().
419 //
420 // * If either call cannot satisfy the allocation request using the
421 // current allocating region, they will try to get a new one. If
422 // this fails, they will attempt to do an evacuation pause and
423 // retry the allocation.
424 //
425 // * If all allocation attempts fail, even after trying to schedule
426 // an evacuation pause, allocate_new_tlab() will return NULL,
427 // whereas mem_allocate() will attempt a heap expansion and/or
428 // schedule a Full GC.
429 //
430 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
431 // should never be called with word_size being humongous. All
432 // humongous allocation requests should go to mem_allocate() which
433 // will satisfy them with a special path.
434
435 virtual HeapWord* allocate_new_tlab(size_t word_size);
436
437 virtual HeapWord* mem_allocate(size_t word_size,
438 bool* gc_overhead_limit_was_exceeded);
439
440 // The following three methods take a gc_count_before_ret
441 // parameter which is used to return the GC count if the method
442 // returns NULL. Given that we are required to read the GC count
443 // while holding the Heap_lock, and these paths will take the
444 // Heap_lock at some point, it's easier to get them to read the GC
445 // count while holding the Heap_lock before they return NULL instead
446 // of the caller (namely: mem_allocate()) having to also take the
447 // Heap_lock just to read the GC count.
448
449 // First-level mutator allocation attempt: try to allocate out of
450 // the mutator alloc region without taking the Heap_lock. This
451 // should only be used for non-humongous allocations.
452 inline HeapWord* attempt_allocation(size_t word_size,
453 uint* gc_count_before_ret,
454 uint* gclocker_retry_count_ret);
455
456 // Second-level mutator allocation attempt: take the Heap_lock and
457 // retry the allocation attempt, potentially scheduling a GC
458 // pause. This should only be used for non-humongous allocations.
459 HeapWord* attempt_allocation_slow(size_t word_size,
460 AllocationContext_t context,
461 uint* gc_count_before_ret,
462 uint* gclocker_retry_count_ret);
463
464 // Takes the Heap_lock and attempts a humongous allocation. It can
465 // potentially schedule a GC pause.
466 HeapWord* attempt_allocation_humongous(size_t word_size,
467 uint* gc_count_before_ret,
468 uint* gclocker_retry_count_ret);
469
470 // Allocation attempt that should be called during safepoints (e.g.,
471 // at the end of a successful GC). expect_null_mutator_alloc_region
472 // specifies whether the mutator alloc region is expected to be NULL
473 // or not.
474 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
475 AllocationContext_t context,
476 bool expect_null_mutator_alloc_region);
477
478 // These methods are the "callbacks" from the G1AllocRegion class.
479
480 // For mutator alloc regions.
481 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
482 void retire_mutator_alloc_region(HeapRegion* alloc_region,
483 size_t allocated_bytes);
484
485 // For GC alloc regions.
486 bool has_more_regions(InCSetState dest);
487 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
488 void retire_gc_alloc_region(HeapRegion* alloc_region,
489 size_t allocated_bytes, InCSetState dest);
490
491 // - if explicit_gc is true, the GC is for a System.gc() etc,
492 // otherwise it's for a failed allocation.
493 // - if clear_all_soft_refs is true, all soft references should be
494 // cleared during the GC.
495 // - it returns false if it is unable to do the collection due to the
496 // GC locker being active, true otherwise.
497 bool do_full_collection(bool explicit_gc,
498 bool clear_all_soft_refs);
499
500 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
501 virtual void do_full_collection(bool clear_all_soft_refs);
502
503 // Resize the heap if necessary after a full collection.
504 void resize_if_necessary_after_full_collection();
505
506 // Callback from VM_G1CollectForAllocation operation.
507 // This function does everything necessary/possible to satisfy a
508 // failed allocation request (including collection, expansion, etc.)
509 HeapWord* satisfy_failed_allocation(size_t word_size,
510 AllocationContext_t context,
511 bool* succeeded);
512 private:
513 // Helper method for satisfy_failed_allocation()
514 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
515 AllocationContext_t context,
516 bool do_gc,
517 bool clear_all_soft_refs,
518 bool expect_null_mutator_alloc_region,
519 bool* gc_succeeded);
520
521 protected:
522 // Attempting to expand the heap sufficiently
523 // to support an allocation of the given "word_size". If
524 // successful, perform the allocation and return the address of the
525 // allocated block, or else "NULL".
526 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
527
528 // Preserve any referents discovered by concurrent marking that have not yet been
529 // copied by the STW pause.
530 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
531 // Process any reference objects discovered during
532 // an incremental evacuation pause.
533 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
534
535 // Enqueue any remaining discovered references
536 // after processing.
537 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
538
539 // Merges the information gathered on a per-thread basis for all worker threads
540 // during GC into global variables.
541 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
542 public:
543 WorkGang* workers() const { return _workers; }
544
545 G1Allocator* allocator() {
546 return _allocator;
547 }
548
549 G1HeapVerifier* verifier() {
550 return _verifier;
551 }
552
553 G1MonitoringSupport* g1mm() {
554 assert(_g1mm != NULL, "should have been initialized");
555 return _g1mm;
556 }
557
558 // Expand the garbage-first heap by at least the given size (in bytes!).
559 // Returns true if the heap was expanded by the requested amount;
560 // false otherwise.
561 // (Rounds up to a HeapRegion boundary.)
562 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
563
564 // Returns the PLAB statistics for a given destination.
565 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
566
567 // Determines PLAB size for a given destination.
568 inline size_t desired_plab_sz(InCSetState dest);
569
570 inline AllocationContextStats& allocation_context_stats();
571
572 // Do anything common to GC's.
573 void gc_prologue(bool full);
574 void gc_epilogue(bool full);
575
576 // Modify the reclaim candidate set and test for presence.
577 // These are only valid for starts_humongous regions.
578 inline void set_humongous_reclaim_candidate(uint region, bool value);
579 inline bool is_humongous_reclaim_candidate(uint region);
580
581 // Remove from the reclaim candidate set. Also remove from the
582 // collection set so that later encounters avoid the slow path.
583 inline void set_humongous_is_live(oop obj);
584
585 // Register the given region to be part of the collection set.
586 inline void register_humongous_region_with_cset(uint index);
587 // Register regions with humongous objects (actually on the start region) in
588 // the in_cset_fast_test table.
589 void register_humongous_regions_with_cset();
590 // We register a region with the fast "in collection set" test. We
591 // simply set to true the array slot corresponding to this region.
592 void register_young_region_with_cset(HeapRegion* r) {
593 _in_cset_fast_test.set_in_young(r->hrm_index());
594 }
595 void register_old_region_with_cset(HeapRegion* r) {
596 _in_cset_fast_test.set_in_old(r->hrm_index());
597 }
598 inline void register_ext_region_with_cset(HeapRegion* r) {
599 _in_cset_fast_test.set_ext(r->hrm_index());
600 }
601 void clear_in_cset(const HeapRegion* hr) {
602 _in_cset_fast_test.clear(hr);
603 }
604
605 void clear_cset_fast_test() {
606 _in_cset_fast_test.clear();
607 }
608
609 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
610
611 // This is called at the start of either a concurrent cycle or a Full
612 // GC to update the number of old marking cycles started.
613 void increment_old_marking_cycles_started();
614
615 // This is called at the end of either a concurrent cycle or a Full
616 // GC to update the number of old marking cycles completed. Those two
617 // can happen in a nested fashion, i.e., we start a concurrent
618 // cycle, a Full GC happens half-way through it which ends first,
619 // and then the cycle notices that a Full GC happened and ends
620 // too. The concurrent parameter is a boolean to help us do a bit
621 // tighter consistency checking in the method. If concurrent is
622 // false, the caller is the inner caller in the nesting (i.e., the
623 // Full GC). If concurrent is true, the caller is the outer caller
624 // in this nesting (i.e., the concurrent cycle). Further nesting is
625 // not currently supported. The end of this call also notifies
626 // the FullGCCount_lock in case a Java thread is waiting for a full
627 // GC to happen (e.g., it called System.gc() with
628 // +ExplicitGCInvokesConcurrent).
629 void increment_old_marking_cycles_completed(bool concurrent);
630
631 uint old_marking_cycles_completed() {
632 return _old_marking_cycles_completed;
633 }
634
635 G1HRPrinter* hr_printer() { return &_hr_printer; }
636
637 // Allocates a new heap region instance.
638 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
639
640 // Allocate the highest free region in the reserved heap. This will commit
641 // regions as necessary.
642 HeapRegion* alloc_highest_free_region();
643
644 // Frees a non-humongous region by initializing its contents and
645 // adding it to the free list that's passed as a parameter (this is
646 // usually a local list which will be appended to the master free
647 // list later). The used bytes of freed regions are accumulated in
648 // pre_used. If skip_remset is true, the region's RSet will not be freed
649 // up. If skip_hot_card_cache is true, the region's hot card cache will not
650 // be freed up. The assumption is that this will be done later.
651 // The locked parameter indicates if the caller has already taken
652 // care of proper synchronization. This may allow some optimizations.
653 void free_region(HeapRegion* hr,
654 FreeRegionList* free_list,
655 bool skip_remset,
656 bool skip_hot_card_cache = false,
657 bool locked = false);
658
659 // It dirties the cards that cover the block so that the post
660 // write barrier never queues anything when updating objects on this
661 // block. It is assumed (and in fact we assert) that the block
662 // belongs to a young region.
663 inline void dirty_young_block(HeapWord* start, size_t word_size);
664
665 // Frees a humongous region by collapsing it into individual regions
666 // and calling free_region() for each of them. The freed regions
667 // will be added to the free list that's passed as a parameter (this
668 // is usually a local list which will be appended to the master free
669 // list later). The used bytes of freed regions are accumulated in
670 // pre_used. If skip_remset is true, the region's RSet will not be freed
671 // up. The assumption is that this will be done later.
672 void free_humongous_region(HeapRegion* hr,
673 FreeRegionList* free_list,
674 bool skip_remset);
675
676 // Facility for allocating in 'archive' regions in high heap memory and
677 // recording the allocated ranges. These should all be called from the
678 // VM thread at safepoints, without the heap lock held. They can be used
679 // to create and archive a set of heap regions which can be mapped at the
680 // same fixed addresses in a subsequent JVM invocation.
681 void begin_archive_alloc_range();
682
683 // Check if the requested size would be too large for an archive allocation.
684 bool is_archive_alloc_too_large(size_t word_size);
685
686 // Allocate memory of the requested size from the archive region. This will
687 // return NULL if the size is too large or if no memory is available. It
688 // does not trigger a garbage collection.
689 HeapWord* archive_mem_allocate(size_t word_size);
690
691 // Optionally aligns the end address and returns the allocated ranges in
692 // an array of MemRegions in order of ascending addresses.
693 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
694 size_t end_alignment_in_bytes = 0);
695
696 // Facility for allocating a fixed range within the heap and marking
697 // the containing regions as 'archive'. For use at JVM init time, when the
698 // caller may mmap archived heap data at the specified range(s).
699 // Verify that the MemRegions specified in the argument array are within the
700 // reserved heap.
701 bool check_archive_addresses(MemRegion* range, size_t count);
702
703 // Commit the appropriate G1 regions containing the specified MemRegions
704 // and mark them as 'archive' regions. The regions in the array must be
705 // non-overlapping and in order of ascending address.
706 bool alloc_archive_regions(MemRegion* range, size_t count);
707
708 // Insert any required filler objects in the G1 regions around the specified
709 // ranges to make the regions parseable. This must be called after
710 // alloc_archive_regions, and after class loading has occurred.
711 void fill_archive_regions(MemRegion* range, size_t count);
712
713 // For each of the specified MemRegions, uncommit the containing G1 regions
714 // which had been allocated by alloc_archive_regions. This should be called
715 // rather than fill_archive_regions at JVM init time if the archive file
716 // mapping failed, with the same non-overlapping and sorted MemRegion array.
717 void dealloc_archive_regions(MemRegion* range, size_t count);
718
719 protected:
720
721 // Shrink the garbage-first heap by at most the given size (in bytes!).
722 // (Rounds down to a HeapRegion boundary.)
723 virtual void shrink(size_t expand_bytes);
724 void shrink_helper(size_t expand_bytes);
725
726 #if TASKQUEUE_STATS
727 static void print_taskqueue_stats_hdr(outputStream* const st);
728 void print_taskqueue_stats() const;
729 void reset_taskqueue_stats();
730 #endif // TASKQUEUE_STATS
731
732 // Schedule the VM operation that will do an evacuation pause to
733 // satisfy an allocation request of word_size. *succeeded will
734 // return whether the VM operation was successful (it did do an
735 // evacuation pause) or not (another thread beat us to it or the GC
736 // locker was active). Given that we should not be holding the
737 // Heap_lock when we enter this method, we will pass the
738 // gc_count_before (i.e., total_collections()) as a parameter since
739 // it has to be read while holding the Heap_lock. Currently, both
740 // methods that call do_collection_pause() release the Heap_lock
741 // before the call, so it's easy to read gc_count_before just before.
742 HeapWord* do_collection_pause(size_t word_size,
743 uint gc_count_before,
744 bool* succeeded,
745 GCCause::Cause gc_cause);
746
747 void wait_for_root_region_scanning();
748
749 // The guts of the incremental collection pause, executed by the vm
750 // thread. It returns false if it is unable to do the collection due
751 // to the GC locker being active, true otherwise
752 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
753
754 // Actually do the work of evacuating the collection set.
755 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
756
757 void pre_evacuate_collection_set();
758 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
759
760 // Print the header for the per-thread termination statistics.
761 static void print_termination_stats_hdr();
762 // Print actual per-thread termination statistics.
763 void print_termination_stats(uint worker_id,
764 double elapsed_ms,
765 double strong_roots_ms,
766 double term_ms,
767 size_t term_attempts,
768 size_t alloc_buffer_waste,
769 size_t undo_waste) const;
770 // Update object copying statistics.
771 void record_obj_copy_mem_stats();
772
773 // The hot card cache for remembered set insertion optimization.
774 G1HotCardCache* _hot_card_cache;
775
776 // The g1 remembered set of the heap.
777 G1RemSet* _g1_rem_set;
778
779 // A set of cards that cover the objects for which the Rsets should be updated
780 // concurrently after the collection.
781 DirtyCardQueueSet _dirty_card_queue_set;
782
783 // The closure used to refine a single card.
784 RefineCardTableEntryClosure* _refine_cte_cl;
785
786 // After a collection pause, convert the regions in the collection set into free
787 // regions.
788 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
789
790 // Abandon the current collection set without recording policy
791 // statistics or updating free lists.
792 void abandon_collection_set(G1CollectionSet* collection_set);
793
794 // The concurrent marker (and the thread it runs in.)
795 G1ConcurrentMark* _cm;
796 ConcurrentMarkThread* _cmThread;
797
798 // The concurrent refiner.
799 ConcurrentG1Refine* _cg1r;
800
801 // The parallel task queues
802 RefToScanQueueSet *_task_queues;
803
804 // True iff a evacuation has failed in the current collection.
805 bool _evacuation_failed;
806
807 EvacuationFailedInfo* _evacuation_failed_info_array;
808
809 // Failed evacuations cause some logical from-space objects to have
810 // forwarding pointers to themselves. Reset them.
811 void remove_self_forwarding_pointers();
812
813 // Restore the objects in the regions in the collection set after an
814 // evacuation failure.
815 void restore_after_evac_failure();
816
817 PreservedMarksSet _preserved_marks_set;
818
819 // Preserve the mark of "obj", if necessary, in preparation for its mark
820 // word being overwritten with a self-forwarding-pointer.
821 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
822
823 #ifndef PRODUCT
824 // Support for forcing evacuation failures. Analogous to
825 // PromotionFailureALot for the other collectors.
826
827 // Records whether G1EvacuationFailureALot should be in effect
828 // for the current GC
829 bool _evacuation_failure_alot_for_current_gc;
830
831 // Used to record the GC number for interval checking when
832 // determining whether G1EvaucationFailureALot is in effect
833 // for the current GC.
834 size_t _evacuation_failure_alot_gc_number;
835
836 // Count of the number of evacuations between failures.
837 volatile size_t _evacuation_failure_alot_count;
838
839 // Set whether G1EvacuationFailureALot should be in effect
840 // for the current GC (based upon the type of GC and which
841 // command line flags are set);
842 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
843 bool during_initial_mark,
844 bool during_marking);
845
846 inline void set_evacuation_failure_alot_for_current_gc();
847
848 // Return true if it's time to cause an evacuation failure.
849 inline bool evacuation_should_fail();
850
851 // Reset the G1EvacuationFailureALot counters. Should be called at
852 // the end of an evacuation pause in which an evacuation failure occurred.
853 inline void reset_evacuation_should_fail();
854 #endif // !PRODUCT
855
856 // ("Weak") Reference processing support.
857 //
858 // G1 has 2 instances of the reference processor class. One
859 // (_ref_processor_cm) handles reference object discovery
860 // and subsequent processing during concurrent marking cycles.
861 //
862 // The other (_ref_processor_stw) handles reference object
863 // discovery and processing during full GCs and incremental
864 // evacuation pauses.
865 //
866 // During an incremental pause, reference discovery will be
867 // temporarily disabled for _ref_processor_cm and will be
868 // enabled for _ref_processor_stw. At the end of the evacuation
869 // pause references discovered by _ref_processor_stw will be
870 // processed and discovery will be disabled. The previous
871 // setting for reference object discovery for _ref_processor_cm
872 // will be re-instated.
873 //
874 // At the start of marking:
875 // * Discovery by the CM ref processor is verified to be inactive
876 // and it's discovered lists are empty.
877 // * Discovery by the CM ref processor is then enabled.
878 //
879 // At the end of marking:
880 // * Any references on the CM ref processor's discovered
881 // lists are processed (possibly MT).
882 //
883 // At the start of full GC we:
884 // * Disable discovery by the CM ref processor and
885 // empty CM ref processor's discovered lists
886 // (without processing any entries).
887 // * Verify that the STW ref processor is inactive and it's
888 // discovered lists are empty.
889 // * Temporarily set STW ref processor discovery as single threaded.
890 // * Temporarily clear the STW ref processor's _is_alive_non_header
891 // field.
892 // * Finally enable discovery by the STW ref processor.
893 //
894 // The STW ref processor is used to record any discovered
895 // references during the full GC.
896 //
897 // At the end of a full GC we:
898 // * Enqueue any reference objects discovered by the STW ref processor
899 // that have non-live referents. This has the side-effect of
900 // making the STW ref processor inactive by disabling discovery.
901 // * Verify that the CM ref processor is still inactive
902 // and no references have been placed on it's discovered
903 // lists (also checked as a precondition during initial marking).
904
905 // The (stw) reference processor...
906 ReferenceProcessor* _ref_processor_stw;
907
908 STWGCTimer* _gc_timer_stw;
909
910 G1NewTracer* _gc_tracer_stw;
911
912 // During reference object discovery, the _is_alive_non_header
913 // closure (if non-null) is applied to the referent object to
914 // determine whether the referent is live. If so then the
915 // reference object does not need to be 'discovered' and can
916 // be treated as a regular oop. This has the benefit of reducing
917 // the number of 'discovered' reference objects that need to
918 // be processed.
919 //
920 // Instance of the is_alive closure for embedding into the
921 // STW reference processor as the _is_alive_non_header field.
922 // Supplying a value for the _is_alive_non_header field is
923 // optional but doing so prevents unnecessary additions to
924 // the discovered lists during reference discovery.
925 G1STWIsAliveClosure _is_alive_closure_stw;
926
927 // The (concurrent marking) reference processor...
928 ReferenceProcessor* _ref_processor_cm;
929
930 // Instance of the concurrent mark is_alive closure for embedding
931 // into the Concurrent Marking reference processor as the
932 // _is_alive_non_header field. Supplying a value for the
933 // _is_alive_non_header field is optional but doing so prevents
934 // unnecessary additions to the discovered lists during reference
935 // discovery.
936 G1CMIsAliveClosure _is_alive_closure_cm;
937
938 volatile bool _free_regions_coming;
939
940 public:
941
942 void set_refine_cte_cl_concurrency(bool concurrent);
943
944 RefToScanQueue *task_queue(uint i) const;
945
946 uint num_task_queues() const;
947
948 // A set of cards where updates happened during the GC
949 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
950
951 // Create a G1CollectedHeap with the specified policy.
952 // Must call the initialize method afterwards.
953 // May not return if something goes wrong.
954 G1CollectedHeap(G1CollectorPolicy* policy);
955
956 // Initialize the G1CollectedHeap to have the initial and
957 // maximum sizes and remembered and barrier sets
958 // specified by the policy object.
959 jint initialize();
960
961 virtual void stop();
962
963 // Return the (conservative) maximum heap alignment for any G1 heap
964 static size_t conservative_max_heap_alignment();
965
966 // Does operations required after initialization has been done.
967 void post_initialize();
968
969 // Initialize weak reference processing.
970 void ref_processing_init();
971
972 virtual Name kind() const {
973 return CollectedHeap::G1CollectedHeap;
974 }
975
976 virtual const char* name() const {
977 return "G1";
978 }
979
980 const G1CollectorState* collector_state() const { return &_collector_state; }
981 G1CollectorState* collector_state() { return &_collector_state; }
982
983 // The current policy object for the collector.
984 G1Policy* g1_policy() const { return _g1_policy; }
985
986 const G1CollectionSet* collection_set() const { return &_collection_set; }
987 G1CollectionSet* collection_set() { return &_collection_set; }
988
989 virtual CollectorPolicy* collector_policy() const;
990
991 // Adaptive size policy. No such thing for g1.
992 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
993
994 // The rem set and barrier set.
995 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
996
997 // Try to minimize the remembered set.
998 void scrub_rem_set();
999
1000 uint get_gc_time_stamp() {
1001 return _gc_time_stamp;
1002 }
1003
1004 inline void reset_gc_time_stamp();
1005
1006 void check_gc_time_stamps() PRODUCT_RETURN;
1007
1008 inline void increment_gc_time_stamp();
1009
1010 // Reset the given region's GC timestamp. If it's starts humongous,
1011 // also reset the GC timestamp of its corresponding
1012 // continues humongous regions too.
1013 void reset_gc_time_stamps(HeapRegion* hr);
1014
1015 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1016 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1017
1018 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1019 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1020
1021 // The shared block offset table array.
1022 G1BlockOffsetTable* bot() const { return _bot; }
1023
1024 // Reference Processing accessors
1025
1026 // The STW reference processor....
1027 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1028
1029 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1030
1031 // The Concurrent Marking reference processor...
1032 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1033
1034 virtual size_t capacity() const;
1035 virtual size_t used() const;
1036 // This should be called when we're not holding the heap lock. The
1037 // result might be a bit inaccurate.
1038 size_t used_unlocked() const;
1039 size_t recalculate_used() const;
1040
1041 // These virtual functions do the actual allocation.
1042 // Some heaps may offer a contiguous region for shared non-blocking
1043 // allocation, via inlined code (by exporting the address of the top and
1044 // end fields defining the extent of the contiguous allocation region.)
1045 // But G1CollectedHeap doesn't yet support this.
1046
1047 virtual bool is_maximal_no_gc() const {
1048 return _hrm.available() == 0;
1049 }
1050
1051 // The current number of regions in the heap.
1052 uint num_regions() const { return _hrm.length(); }
1053
1054 // The max number of regions in the heap.
1055 uint max_regions() const { return _hrm.max_length(); }
1056
1057 // The number of regions that are completely free.
1058 uint num_free_regions() const { return _hrm.num_free_regions(); }
1059
1060 MemoryUsage get_auxiliary_data_memory_usage() const {
1061 return _hrm.get_auxiliary_data_memory_usage();
1062 }
1063
1064 // The number of regions that are not completely free.
1065 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1066
1067 #ifdef ASSERT
1068 bool is_on_master_free_list(HeapRegion* hr) {
1069 return _hrm.is_free(hr);
1070 }
1071 #endif // ASSERT
1072
1073 // Wrapper for the region list operations that can be called from
1074 // methods outside this class.
1075
1076 void secondary_free_list_add(FreeRegionList* list) {
1077 _secondary_free_list.add_ordered(list);
1078 }
1079
1080 void append_secondary_free_list() {
1081 _hrm.insert_list_into_free_list(&_secondary_free_list);
1082 }
1083
1084 void append_secondary_free_list_if_not_empty_with_lock() {
1085 // If the secondary free list looks empty there's no reason to
1086 // take the lock and then try to append it.
1087 if (!_secondary_free_list.is_empty()) {
1088 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1089 append_secondary_free_list();
1090 }
1091 }
1092
1093 inline void old_set_add(HeapRegion* hr);
1094 inline void old_set_remove(HeapRegion* hr);
1095
1096 size_t non_young_capacity_bytes() {
1097 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1098 }
1099
1100 void set_free_regions_coming();
1101 void reset_free_regions_coming();
1102 bool free_regions_coming() { return _free_regions_coming; }
1103 void wait_while_free_regions_coming();
1104
1105 // Determine whether the given region is one that we are using as an
1106 // old GC alloc region.
1107 bool is_old_gc_alloc_region(HeapRegion* hr);
1108
1109 // Perform a collection of the heap; intended for use in implementing
1110 // "System.gc". This probably implies as full a collection as the
1111 // "CollectedHeap" supports.
1112 virtual void collect(GCCause::Cause cause);
1113
1114 virtual bool copy_allocation_context_stats(const jint* contexts,
1115 jlong* totals,
1116 jbyte* accuracy,
1117 jint len);
1118
1119 // True iff an evacuation has failed in the most-recent collection.
1120 bool evacuation_failed() { return _evacuation_failed; }
1121
1122 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1123 void prepend_to_freelist(FreeRegionList* list);
1124 void decrement_summary_bytes(size_t bytes);
1125
1126 virtual bool is_in(const void* p) const;
1127 #ifdef ASSERT
1128 // Returns whether p is in one of the available areas of the heap. Slow but
1129 // extensive version.
1130 bool is_in_exact(const void* p) const;
1131 #endif
1132
1133 // Return "TRUE" iff the given object address is within the collection
1134 // set. Assumes that the reference points into the heap.
1135 inline bool is_in_cset(const HeapRegion *hr);
1136 inline bool is_in_cset(oop obj);
1137
1138 inline bool is_in_cset_or_humongous(const oop obj);
1139
1140 private:
1141 // This array is used for a quick test on whether a reference points into
1142 // the collection set or not. Each of the array's elements denotes whether the
1143 // corresponding region is in the collection set or not.
1144 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1145
1146 public:
1147
1148 inline InCSetState in_cset_state(const oop obj);
1149
1150 // Return "TRUE" iff the given object address is in the reserved
1151 // region of g1.
1152 bool is_in_g1_reserved(const void* p) const {
1153 return _hrm.reserved().contains(p);
1154 }
1155
1156 // Returns a MemRegion that corresponds to the space that has been
1157 // reserved for the heap
1158 MemRegion g1_reserved() const {
1159 return _hrm.reserved();
1160 }
1161
1162 virtual bool is_in_closed_subset(const void* p) const;
1163
1164 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1165 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1166 }
1167
1168 // Iteration functions.
1169
1170 // Iterate over all objects, calling "cl.do_object" on each.
1171 virtual void object_iterate(ObjectClosure* cl);
1172
1173 virtual void safe_object_iterate(ObjectClosure* cl) {
1174 object_iterate(cl);
1175 }
1176
1177 // Iterate over heap regions, in address order, terminating the
1178 // iteration early if the "doHeapRegion" method returns "true".
1179 void heap_region_iterate(HeapRegionClosure* blk) const;
1180
1181 // Return the region with the given index. It assumes the index is valid.
1182 inline HeapRegion* region_at(uint index) const;
1183
1184 // Return the next region (by index) that is part of the same
1185 // humongous object that hr is part of.
1186 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1187
1188 // Calculate the region index of the given address. Given address must be
1189 // within the heap.
1190 inline uint addr_to_region(HeapWord* addr) const;
1191
1192 inline HeapWord* bottom_addr_for_region(uint index) const;
1193
1194 // Iterate over the heap regions in parallel. Assumes that this will be called
1195 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1196 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1197 // to each of the regions, by attempting to claim the region using the
1198 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1199 // region. The concurrent argument should be set to true if iteration is
1200 // performed concurrently, during which no assumptions are made for consistent
1201 // attributes of the heap regions (as they might be modified while iterating).
1202 void heap_region_par_iterate(HeapRegionClosure* cl,
1203 uint worker_id,
1204 HeapRegionClaimer* hrclaimer,
1205 bool concurrent = false) const;
1206
1207 // Iterate over the regions (if any) in the current collection set.
1208 void collection_set_iterate(HeapRegionClosure* blk);
1209
1210 // Iterate over the regions (if any) in the current collection set. Starts the
1211 // iteration over the entire collection set so that the start regions of a given
1212 // worker id over the set active_workers are evenly spread across the set of
1213 // collection set regions.
1214 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1215
1216 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1217
1218 // Returns the HeapRegion that contains addr. addr must not be NULL.
1219 template <class T>
1220 inline HeapRegion* heap_region_containing(const T addr) const;
1221
1222 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1223 // each address in the (reserved) heap is a member of exactly
1224 // one block. The defining characteristic of a block is that it is
1225 // possible to find its size, and thus to progress forward to the next
1226 // block. (Blocks may be of different sizes.) Thus, blocks may
1227 // represent Java objects, or they might be free blocks in a
1228 // free-list-based heap (or subheap), as long as the two kinds are
1229 // distinguishable and the size of each is determinable.
1230
1231 // Returns the address of the start of the "block" that contains the
1232 // address "addr". We say "blocks" instead of "object" since some heaps
1233 // may not pack objects densely; a chunk may either be an object or a
1234 // non-object.
1235 virtual HeapWord* block_start(const void* addr) const;
1236
1237 // Requires "addr" to be the start of a chunk, and returns its size.
1238 // "addr + size" is required to be the start of a new chunk, or the end
1239 // of the active area of the heap.
1240 virtual size_t block_size(const HeapWord* addr) const;
1241
1242 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1243 // the block is an object.
1244 virtual bool block_is_obj(const HeapWord* addr) const;
1245
1246 // Section on thread-local allocation buffers (TLABs)
1247 // See CollectedHeap for semantics.
1248
1249 bool supports_tlab_allocation() const;
1250 size_t tlab_capacity(Thread* ignored) const;
1251 size_t tlab_used(Thread* ignored) const;
1252 size_t max_tlab_size() const;
1253 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1254
1255 // Can a compiler initialize a new object without store barriers?
1256 // This permission only extends from the creation of a new object
1257 // via a TLAB up to the first subsequent safepoint. If such permission
1258 // is granted for this heap type, the compiler promises to call
1259 // defer_store_barrier() below on any slow path allocation of
1260 // a new object for which such initializing store barriers will
1261 // have been elided. G1, like CMS, allows this, but should be
1262 // ready to provide a compensating write barrier as necessary
1263 // if that storage came out of a non-young region. The efficiency
1264 // of this implementation depends crucially on being able to
1265 // answer very efficiently in constant time whether a piece of
1266 // storage in the heap comes from a young region or not.
1267 // See ReduceInitialCardMarks.
1268 virtual bool can_elide_tlab_store_barriers() const {
1269 return true;
1270 }
1271
1272 virtual bool card_mark_must_follow_store() const {
1273 return true;
1274 }
1275
1276 inline bool is_in_young(const oop obj);
1277
1278 virtual bool is_scavengable(const void* addr);
1279
1280 // We don't need barriers for initializing stores to objects
1281 // in the young gen: for the SATB pre-barrier, there is no
1282 // pre-value that needs to be remembered; for the remembered-set
1283 // update logging post-barrier, we don't maintain remembered set
1284 // information for young gen objects.
1285 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1286
1287 // Returns "true" iff the given word_size is "very large".
1288 static bool is_humongous(size_t word_size) {
1289 // Note this has to be strictly greater-than as the TLABs
1290 // are capped at the humongous threshold and we want to
1291 // ensure that we don't try to allocate a TLAB as
1292 // humongous and that we don't allocate a humongous
1293 // object in a TLAB.
1294 return word_size > _humongous_object_threshold_in_words;
1295 }
1296
1297 // Returns the humongous threshold for a specific region size
1298 static size_t humongous_threshold_for(size_t region_size) {
1299 return (region_size / 2);
1300 }
1301
1302 // Returns the number of regions the humongous object of the given word size
1303 // requires.
1304 static size_t humongous_obj_size_in_regions(size_t word_size);
1305
1306 // Print the maximum heap capacity.
1307 virtual size_t max_capacity() const;
1308
1309 virtual jlong millis_since_last_gc();
1310
1311
1312 // Convenience function to be used in situations where the heap type can be
1313 // asserted to be this type.
1314 static G1CollectedHeap* heap();
1315
1316 void set_region_short_lived_locked(HeapRegion* hr);
1317 // add appropriate methods for any other surv rate groups
1318
1319 const G1SurvivorRegions* survivor() const { return &_survivor; }
1320
1321 uint survivor_regions_count() const {
1322 return _survivor.length();
1323 }
1324
1325 uint eden_regions_count() const {
1326 return _eden.length();
1327 }
1328
1329 uint young_regions_count() const {
1330 return _eden.length() + _survivor.length();
1331 }
1332
1333 uint old_regions_count() const { return _old_set.length(); }
1334
1335 uint humongous_regions_count() const { return _humongous_set.length(); }
1336
1337 #ifdef ASSERT
1338 bool check_young_list_empty();
1339 #endif
1340
1341 // *** Stuff related to concurrent marking. It's not clear to me that so
1342 // many of these need to be public.
1343
1344 // The functions below are helper functions that a subclass of
1345 // "CollectedHeap" can use in the implementation of its virtual
1346 // functions.
1347 // This performs a concurrent marking of the live objects in a
1348 // bitmap off to the side.
1349 void doConcurrentMark();
1350
1351 bool isMarkedPrev(oop obj) const;
1352 bool isMarkedNext(oop obj) const;
1353
1354 // Determine if an object is dead, given the object and also
1355 // the region to which the object belongs. An object is dead
1356 // iff a) it was not allocated since the last mark, b) it
1357 // is not marked, and c) it is not in an archive region.
1358 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1359 return
1360 !hr->obj_allocated_since_prev_marking(obj) &&
1361 !isMarkedPrev(obj) &&
1362 !hr->is_archive();
1363 }
1364
1365 // This function returns true when an object has been
1366 // around since the previous marking and hasn't yet
1367 // been marked during this marking, and is not in an archive region.
1368 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1369 return
1370 !hr->obj_allocated_since_next_marking(obj) &&
1371 !isMarkedNext(obj) &&
1372 !hr->is_archive();
1373 }
1374
1375 // Determine if an object is dead, given only the object itself.
1376 // This will find the region to which the object belongs and
1377 // then call the region version of the same function.
1378
1379 // Added if it is NULL it isn't dead.
1380
1381 inline bool is_obj_dead(const oop obj) const;
1382
1383 inline bool is_obj_ill(const oop obj) const;
1384
1385 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1386
1387 // Refinement
1388
1389 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1390
1391 // Optimized nmethod scanning support routines
1392
1393 // Register the given nmethod with the G1 heap.
1394 virtual void register_nmethod(nmethod* nm);
1395
1396 // Unregister the given nmethod from the G1 heap.
1397 virtual void unregister_nmethod(nmethod* nm);
1398
1399 // Free up superfluous code root memory.
1400 void purge_code_root_memory();
1401
1402 // Rebuild the strong code root lists for each region
1403 // after a full GC.
1404 void rebuild_strong_code_roots();
1405
1406 // Delete entries for dead interned string and clean up unreferenced symbols
1407 // in symbol table, possibly in parallel.
1408 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1409
1410 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1411 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1412
1413 // Redirty logged cards in the refinement queue.
1414 void redirty_logged_cards();
1415 // Verification
1416
1417 // Perform any cleanup actions necessary before allowing a verification.
1418 virtual void prepare_for_verify();
1419
1420 // Perform verification.
1421
1422 // vo == UsePrevMarking -> use "prev" marking information,
1423 // vo == UseNextMarking -> use "next" marking information
1424 // vo == UseMarkWord -> use the mark word in the object header
1425 //
1426 // NOTE: Only the "prev" marking information is guaranteed to be
1427 // consistent most of the time, so most calls to this should use
1428 // vo == UsePrevMarking.
1429 // Currently, there is only one case where this is called with
1430 // vo == UseNextMarking, which is to verify the "next" marking
1431 // information at the end of remark.
1432 // Currently there is only one place where this is called with
1433 // vo == UseMarkWord, which is to verify the marking during a
1434 // full GC.
1435 void verify(VerifyOption vo);
1436
1437 // The methods below are here for convenience and dispatch the
1438 // appropriate method depending on value of the given VerifyOption
1439 // parameter. The values for that parameter, and their meanings,
1440 // are the same as those above.
1441
1442 bool is_obj_dead_cond(const oop obj,
1443 const HeapRegion* hr,
1444 const VerifyOption vo) const;
1445
1446 bool is_obj_dead_cond(const oop obj,
1447 const VerifyOption vo) const;
1448
1449 G1HeapSummary create_g1_heap_summary();
1450 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1451
1452 // Printing
1453 private:
1454 void print_heap_regions() const;
1455 void print_regions_on(outputStream* st) const;
1456
1457 public:
1458 virtual void print_on(outputStream* st) const;
1459 virtual void print_extended_on(outputStream* st) const;
1460 virtual void print_on_error(outputStream* st) const;
1461
1462 virtual void print_gc_threads_on(outputStream* st) const;
1463 virtual void gc_threads_do(ThreadClosure* tc) const;
1464
1465 // Override
1466 void print_tracing_info() const;
1467
1468 // The following two methods are helpful for debugging RSet issues.
1469 void print_cset_rsets() PRODUCT_RETURN;
1470 void print_all_rsets() PRODUCT_RETURN;
1471
1472 public:
1473 size_t pending_card_num();
1474
1475 protected:
1476 size_t _max_heap_capacity;
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 RefToScanQueueSet* _queues;
1491 ParallelTaskTerminator* _terminator;
1492
1493 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1494 RefToScanQueueSet* queues() { return _queues; }
1495 ParallelTaskTerminator* terminator() { return _terminator; }
1496
1497 public:
1498 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1499 G1ParScanThreadState* par_scan_state,
1500 RefToScanQueueSet* queues,
1501 ParallelTaskTerminator* terminator)
1502 : _g1h(g1h), _par_scan_state(par_scan_state),
1503 _queues(queues), _terminator(terminator),
1504 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1505
1506 void do_void();
1507
1508 double term_time() const { return _term_time; }
1509 size_t term_attempts() const { return _term_attempts; }
1510
1511 private:
1512 inline bool offer_termination();
1513 };
1514
1515 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP