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_heap_monitoring();
307 void process_weak_jni_handles();
308
309 // These are macros so that, if the assert fires, we get the correct
310 // line number, file, etc.
311
312 #define heap_locking_asserts_params(_extra_message_) \
313 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
314 (_extra_message_), \
315 BOOL_TO_STR(Heap_lock->owned_by_self()), \
316 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
317 BOOL_TO_STR(Thread::current()->is_VM_thread())
318
319 #define assert_heap_locked() \
320 do { \
321 assert(Heap_lock->owned_by_self(), \
322 heap_locking_asserts_params("should be holding the Heap_lock")); \
323 } while (0)
324
325 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
326 do { \
327 assert(Heap_lock->owned_by_self() || \
328 (SafepointSynchronize::is_at_safepoint() && \
329 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
330 heap_locking_asserts_params("should be holding the Heap_lock or " \
331 "should be at a safepoint")); \
332 } while (0)
333
334 #define assert_heap_locked_and_not_at_safepoint() \
335 do { \
336 assert(Heap_lock->owned_by_self() && \
337 !SafepointSynchronize::is_at_safepoint(), \
338 heap_locking_asserts_params("should be holding the Heap_lock and " \
339 "should not be at a safepoint")); \
340 } while (0)
341
342 #define assert_heap_not_locked() \
343 do { \
344 assert(!Heap_lock->owned_by_self(), \
345 heap_locking_asserts_params("should not be holding the Heap_lock")); \
346 } while (0)
347
348 #define assert_heap_not_locked_and_not_at_safepoint() \
349 do { \
350 assert(!Heap_lock->owned_by_self() && \
351 !SafepointSynchronize::is_at_safepoint(), \
352 heap_locking_asserts_params("should not be holding the Heap_lock and " \
353 "should not be at a safepoint")); \
354 } while (0)
355
356 #define assert_at_safepoint(_should_be_vm_thread_) \
357 do { \
358 assert(SafepointSynchronize::is_at_safepoint() && \
359 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
360 heap_locking_asserts_params("should be at a safepoint")); \
361 } while (0)
362
363 #define assert_not_at_safepoint() \
364 do { \
365 assert(!SafepointSynchronize::is_at_safepoint(), \
366 heap_locking_asserts_params("should not be at a safepoint")); \
367 } while (0)
368
369 protected:
370
371 // The young region list.
372 G1EdenRegions _eden;
373 G1SurvivorRegions _survivor;
374
375 // The current policy object for the collector.
376 G1Policy* _g1_policy;
377 G1HeapSizingPolicy* _heap_sizing_policy;
378
379 G1CollectionSet _collection_set;
380
381 // This is the second level of trying to allocate a new region. If
382 // new_region() didn't find a region on the free_list, this call will
383 // check whether there's anything available on the
384 // secondary_free_list and/or wait for more regions to appear on
385 // that list, if _free_regions_coming is set.
386 HeapRegion* new_region_try_secondary_free_list(bool is_old);
387
388 // Try to allocate a single non-humongous HeapRegion sufficient for
389 // an allocation of the given word_size. If do_expand is true,
390 // attempt to expand the heap if necessary to satisfy the allocation
391 // request. If the region is to be used as an old region or for a
392 // humongous object, set is_old to true. If not, to false.
393 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
394
395 // Initialize a contiguous set of free regions of length num_regions
396 // and starting at index first so that they appear as a single
397 // humongous region.
398 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
399 uint num_regions,
400 size_t word_size,
401 AllocationContext_t context);
402
403 // Attempt to allocate a humongous object of the given size. Return
404 // NULL if unsuccessful.
405 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
406
407 // The following two methods, allocate_new_tlab() and
408 // mem_allocate(), are the two main entry points from the runtime
409 // into the G1's allocation routines. They have the following
410 // assumptions:
411 //
412 // * They should both be called outside safepoints.
413 //
414 // * They should both be called without holding the Heap_lock.
415 //
416 // * All allocation requests for new TLABs should go to
417 // allocate_new_tlab().
418 //
419 // * All non-TLAB allocation requests should go to mem_allocate().
420 //
421 // * If either call cannot satisfy the allocation request using the
422 // current allocating region, they will try to get a new one. If
423 // this fails, they will attempt to do an evacuation pause and
424 // retry the allocation.
425 //
426 // * If all allocation attempts fail, even after trying to schedule
427 // an evacuation pause, allocate_new_tlab() will return NULL,
428 // whereas mem_allocate() will attempt a heap expansion and/or
429 // schedule a Full GC.
430 //
431 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
432 // should never be called with word_size being humongous. All
433 // humongous allocation requests should go to mem_allocate() which
434 // will satisfy them with a special path.
435
436 virtual HeapWord* allocate_new_tlab(size_t word_size);
437
438 virtual HeapWord* mem_allocate(size_t word_size,
439 bool* gc_overhead_limit_was_exceeded);
440
441 // The following three methods take a gc_count_before_ret
442 // parameter which is used to return the GC count if the method
443 // returns NULL. Given that we are required to read the GC count
444 // while holding the Heap_lock, and these paths will take the
445 // Heap_lock at some point, it's easier to get them to read the GC
446 // count while holding the Heap_lock before they return NULL instead
447 // of the caller (namely: mem_allocate()) having to also take the
448 // Heap_lock just to read the GC count.
449
450 // First-level mutator allocation attempt: try to allocate out of
451 // the mutator alloc region without taking the Heap_lock. This
452 // should only be used for non-humongous allocations.
453 inline HeapWord* attempt_allocation(size_t word_size,
454 uint* gc_count_before_ret,
455 uint* gclocker_retry_count_ret);
456
457 // Second-level mutator allocation attempt: take the Heap_lock and
458 // retry the allocation attempt, potentially scheduling a GC
459 // pause. This should only be used for non-humongous allocations.
460 HeapWord* attempt_allocation_slow(size_t word_size,
461 AllocationContext_t context,
462 uint* gc_count_before_ret,
463 uint* gclocker_retry_count_ret);
464
465 // Takes the Heap_lock and attempts a humongous allocation. It can
466 // potentially schedule a GC pause.
467 HeapWord* attempt_allocation_humongous(size_t word_size,
468 uint* gc_count_before_ret,
469 uint* gclocker_retry_count_ret);
470
471 // Allocation attempt that should be called during safepoints (e.g.,
472 // at the end of a successful GC). expect_null_mutator_alloc_region
473 // specifies whether the mutator alloc region is expected to be NULL
474 // or not.
475 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
476 AllocationContext_t context,
477 bool expect_null_mutator_alloc_region);
478
479 // These methods are the "callbacks" from the G1AllocRegion class.
480
481 // For mutator alloc regions.
482 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
483 void retire_mutator_alloc_region(HeapRegion* alloc_region,
484 size_t allocated_bytes);
485
486 // For GC alloc regions.
487 bool has_more_regions(InCSetState dest);
488 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
489 void retire_gc_alloc_region(HeapRegion* alloc_region,
490 size_t allocated_bytes, InCSetState dest);
491
492 // - if explicit_gc is true, the GC is for a System.gc() etc,
493 // otherwise it's for a failed allocation.
494 // - if clear_all_soft_refs is true, all soft references should be
495 // cleared during the GC.
496 // - it returns false if it is unable to do the collection due to the
497 // GC locker being active, true otherwise.
498 bool do_full_collection(bool explicit_gc,
499 bool clear_all_soft_refs);
500
501 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
502 virtual void do_full_collection(bool clear_all_soft_refs);
503
504 // Resize the heap if necessary after a full collection.
505 void resize_if_necessary_after_full_collection();
506
507 // Callback from VM_G1CollectForAllocation operation.
508 // This function does everything necessary/possible to satisfy a
509 // failed allocation request (including collection, expansion, etc.)
510 HeapWord* satisfy_failed_allocation(size_t word_size,
511 AllocationContext_t context,
512 bool* succeeded);
513 private:
514 // Helper method for satisfy_failed_allocation()
515 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
516 AllocationContext_t context,
517 bool do_gc,
518 bool clear_all_soft_refs,
519 bool expect_null_mutator_alloc_region,
520 bool* gc_succeeded);
521
522 protected:
523 // Attempting to expand the heap sufficiently
524 // to support an allocation of the given "word_size". If
525 // successful, perform the allocation and return the address of the
526 // allocated block, or else "NULL".
527 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
528
529 // Preserve any referents discovered by concurrent marking that have not yet been
530 // copied by the STW pause.
531 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
532 // Process any reference objects discovered during
533 // an incremental evacuation pause.
534 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
535
536 // Enqueue any remaining discovered references
537 // after processing.
538 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
539
540 // Merges the information gathered on a per-thread basis for all worker threads
541 // during GC into global variables.
542 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
543 public:
544 WorkGang* workers() const { return _workers; }
545
546 G1Allocator* allocator() {
547 return _allocator;
548 }
549
550 G1HeapVerifier* verifier() {
551 return _verifier;
552 }
553
554 G1MonitoringSupport* g1mm() {
555 assert(_g1mm != NULL, "should have been initialized");
556 return _g1mm;
557 }
558
559 // Expand the garbage-first heap by at least the given size (in bytes!).
560 // Returns true if the heap was expanded by the requested amount;
561 // false otherwise.
562 // (Rounds up to a HeapRegion boundary.)
563 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
564
565 // Returns the PLAB statistics for a given destination.
566 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
567
568 // Determines PLAB size for a given destination.
569 inline size_t desired_plab_sz(InCSetState dest);
570
571 inline AllocationContextStats& allocation_context_stats();
572
573 // Do anything common to GC's.
574 void gc_prologue(bool full);
575 void gc_epilogue(bool full);
576
577 // Modify the reclaim candidate set and test for presence.
578 // These are only valid for starts_humongous regions.
579 inline void set_humongous_reclaim_candidate(uint region, bool value);
580 inline bool is_humongous_reclaim_candidate(uint region);
581
582 // Remove from the reclaim candidate set. Also remove from the
583 // collection set so that later encounters avoid the slow path.
584 inline void set_humongous_is_live(oop obj);
585
586 // Register the given region to be part of the collection set.
587 inline void register_humongous_region_with_cset(uint index);
588 // Register regions with humongous objects (actually on the start region) in
589 // the in_cset_fast_test table.
590 void register_humongous_regions_with_cset();
591 // We register a region with the fast "in collection set" test. We
592 // simply set to true the array slot corresponding to this region.
593 void register_young_region_with_cset(HeapRegion* r) {
594 _in_cset_fast_test.set_in_young(r->hrm_index());
595 }
596 void register_old_region_with_cset(HeapRegion* r) {
597 _in_cset_fast_test.set_in_old(r->hrm_index());
598 }
599 inline void register_ext_region_with_cset(HeapRegion* r) {
600 _in_cset_fast_test.set_ext(r->hrm_index());
601 }
602 void clear_in_cset(const HeapRegion* hr) {
603 _in_cset_fast_test.clear(hr);
604 }
605
606 void clear_cset_fast_test() {
607 _in_cset_fast_test.clear();
608 }
609
610 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
611
612 // This is called at the start of either a concurrent cycle or a Full
613 // GC to update the number of old marking cycles started.
614 void increment_old_marking_cycles_started();
615
616 // This is called at the end of either a concurrent cycle or a Full
617 // GC to update the number of old marking cycles completed. Those two
618 // can happen in a nested fashion, i.e., we start a concurrent
619 // cycle, a Full GC happens half-way through it which ends first,
620 // and then the cycle notices that a Full GC happened and ends
621 // too. The concurrent parameter is a boolean to help us do a bit
622 // tighter consistency checking in the method. If concurrent is
623 // false, the caller is the inner caller in the nesting (i.e., the
624 // Full GC). If concurrent is true, the caller is the outer caller
625 // in this nesting (i.e., the concurrent cycle). Further nesting is
626 // not currently supported. The end of this call also notifies
627 // the FullGCCount_lock in case a Java thread is waiting for a full
628 // GC to happen (e.g., it called System.gc() with
629 // +ExplicitGCInvokesConcurrent).
630 void increment_old_marking_cycles_completed(bool concurrent);
631
632 uint old_marking_cycles_completed() {
633 return _old_marking_cycles_completed;
634 }
635
636 G1HRPrinter* hr_printer() { return &_hr_printer; }
637
638 // Allocates a new heap region instance.
639 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
640
641 // Allocate the highest free region in the reserved heap. This will commit
642 // regions as necessary.
643 HeapRegion* alloc_highest_free_region();
644
645 // Frees a non-humongous region by initializing its contents and
646 // adding it to the free list that's passed as a parameter (this is
647 // usually a local list which will be appended to the master free
648 // list later). The used bytes of freed regions are accumulated in
649 // pre_used. If skip_remset is true, the region's RSet will not be freed
650 // up. If skip_hot_card_cache is true, the region's hot card cache will not
651 // be freed up. The assumption is that this will be done later.
652 // The locked parameter indicates if the caller has already taken
653 // care of proper synchronization. This may allow some optimizations.
654 void free_region(HeapRegion* hr,
655 FreeRegionList* free_list,
656 bool skip_remset,
657 bool skip_hot_card_cache = false,
658 bool locked = false);
659
660 // It dirties the cards that cover the block so that the post
661 // write barrier never queues anything when updating objects on this
662 // block. It is assumed (and in fact we assert) that the block
663 // belongs to a young region.
664 inline void dirty_young_block(HeapWord* start, size_t word_size);
665
666 // Frees a humongous region by collapsing it into individual regions
667 // and calling free_region() for each of them. The freed regions
668 // will be added to the free list that's passed as a parameter (this
669 // is usually a local list which will be appended to the master free
670 // list later). The used bytes of freed regions are accumulated in
671 // pre_used. If skip_remset is true, the region's RSet will not be freed
672 // up. The assumption is that this will be done later.
673 void free_humongous_region(HeapRegion* hr,
674 FreeRegionList* free_list,
675 bool skip_remset);
676
677 // Facility for allocating in 'archive' regions in high heap memory and
678 // recording the allocated ranges. These should all be called from the
679 // VM thread at safepoints, without the heap lock held. They can be used
680 // to create and archive a set of heap regions which can be mapped at the
681 // same fixed addresses in a subsequent JVM invocation.
682 void begin_archive_alloc_range();
683
684 // Check if the requested size would be too large for an archive allocation.
685 bool is_archive_alloc_too_large(size_t word_size);
686
687 // Allocate memory of the requested size from the archive region. This will
688 // return NULL if the size is too large or if no memory is available. It
689 // does not trigger a garbage collection.
690 HeapWord* archive_mem_allocate(size_t word_size);
691
692 // Optionally aligns the end address and returns the allocated ranges in
693 // an array of MemRegions in order of ascending addresses.
694 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
695 size_t end_alignment_in_bytes = 0);
696
697 // Facility for allocating a fixed range within the heap and marking
698 // the containing regions as 'archive'. For use at JVM init time, when the
699 // caller may mmap archived heap data at the specified range(s).
700 // Verify that the MemRegions specified in the argument array are within the
701 // reserved heap.
702 bool check_archive_addresses(MemRegion* range, size_t count);
703
704 // Commit the appropriate G1 regions containing the specified MemRegions
705 // and mark them as 'archive' regions. The regions in the array must be
706 // non-overlapping and in order of ascending address.
707 bool alloc_archive_regions(MemRegion* range, size_t count);
708
709 // Insert any required filler objects in the G1 regions around the specified
710 // ranges to make the regions parseable. This must be called after
711 // alloc_archive_regions, and after class loading has occurred.
712 void fill_archive_regions(MemRegion* range, size_t count);
713
714 // For each of the specified MemRegions, uncommit the containing G1 regions
715 // which had been allocated by alloc_archive_regions. This should be called
716 // rather than fill_archive_regions at JVM init time if the archive file
717 // mapping failed, with the same non-overlapping and sorted MemRegion array.
718 void dealloc_archive_regions(MemRegion* range, size_t count);
719
720 protected:
721
722 // Shrink the garbage-first heap by at most the given size (in bytes!).
723 // (Rounds down to a HeapRegion boundary.)
724 virtual void shrink(size_t expand_bytes);
725 void shrink_helper(size_t expand_bytes);
726
727 #if TASKQUEUE_STATS
728 static void print_taskqueue_stats_hdr(outputStream* const st);
729 void print_taskqueue_stats() const;
730 void reset_taskqueue_stats();
731 #endif // TASKQUEUE_STATS
732
733 // Schedule the VM operation that will do an evacuation pause to
734 // satisfy an allocation request of word_size. *succeeded will
735 // return whether the VM operation was successful (it did do an
736 // evacuation pause) or not (another thread beat us to it or the GC
737 // locker was active). Given that we should not be holding the
738 // Heap_lock when we enter this method, we will pass the
739 // gc_count_before (i.e., total_collections()) as a parameter since
740 // it has to be read while holding the Heap_lock. Currently, both
741 // methods that call do_collection_pause() release the Heap_lock
742 // before the call, so it's easy to read gc_count_before just before.
743 HeapWord* do_collection_pause(size_t word_size,
744 uint gc_count_before,
745 bool* succeeded,
746 GCCause::Cause gc_cause);
747
748 void wait_for_root_region_scanning();
749
750 // The guts of the incremental collection pause, executed by the vm
751 // thread. It returns false if it is unable to do the collection due
752 // to the GC locker being active, true otherwise
753 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
754
755 // Actually do the work of evacuating the collection set.
756 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
757
758 void pre_evacuate_collection_set();
759 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
760
761 // Print the header for the per-thread termination statistics.
762 static void print_termination_stats_hdr();
763 // Print actual per-thread termination statistics.
764 void print_termination_stats(uint worker_id,
765 double elapsed_ms,
766 double strong_roots_ms,
767 double term_ms,
768 size_t term_attempts,
769 size_t alloc_buffer_waste,
770 size_t undo_waste) const;
771 // Update object copying statistics.
772 void record_obj_copy_mem_stats();
773
774 // The hot card cache for remembered set insertion optimization.
775 G1HotCardCache* _hot_card_cache;
776
777 // The g1 remembered set of the heap.
778 G1RemSet* _g1_rem_set;
779
780 // A set of cards that cover the objects for which the Rsets should be updated
781 // concurrently after the collection.
782 DirtyCardQueueSet _dirty_card_queue_set;
783
784 // The closure used to refine a single card.
785 RefineCardTableEntryClosure* _refine_cte_cl;
786
787 // After a collection pause, convert the regions in the collection set into free
788 // regions.
789 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
790
791 // Abandon the current collection set without recording policy
792 // statistics or updating free lists.
793 void abandon_collection_set(G1CollectionSet* collection_set);
794
795 // The concurrent marker (and the thread it runs in.)
796 G1ConcurrentMark* _cm;
797 ConcurrentMarkThread* _cmThread;
798
799 // The concurrent refiner.
800 ConcurrentG1Refine* _cg1r;
801
802 // The parallel task queues
803 RefToScanQueueSet *_task_queues;
804
805 // True iff a evacuation has failed in the current collection.
806 bool _evacuation_failed;
807
808 EvacuationFailedInfo* _evacuation_failed_info_array;
809
810 // Failed evacuations cause some logical from-space objects to have
811 // forwarding pointers to themselves. Reset them.
812 void remove_self_forwarding_pointers();
813
814 // Restore the objects in the regions in the collection set after an
815 // evacuation failure.
816 void restore_after_evac_failure();
817
818 PreservedMarksSet _preserved_marks_set;
819
820 // Preserve the mark of "obj", if necessary, in preparation for its mark
821 // word being overwritten with a self-forwarding-pointer.
822 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
823
824 #ifndef PRODUCT
825 // Support for forcing evacuation failures. Analogous to
826 // PromotionFailureALot for the other collectors.
827
828 // Records whether G1EvacuationFailureALot should be in effect
829 // for the current GC
830 bool _evacuation_failure_alot_for_current_gc;
831
832 // Used to record the GC number for interval checking when
833 // determining whether G1EvaucationFailureALot is in effect
834 // for the current GC.
835 size_t _evacuation_failure_alot_gc_number;
836
837 // Count of the number of evacuations between failures.
838 volatile size_t _evacuation_failure_alot_count;
839
840 // Set whether G1EvacuationFailureALot should be in effect
841 // for the current GC (based upon the type of GC and which
842 // command line flags are set);
843 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
844 bool during_initial_mark,
845 bool during_marking);
846
847 inline void set_evacuation_failure_alot_for_current_gc();
848
849 // Return true if it's time to cause an evacuation failure.
850 inline bool evacuation_should_fail();
851
852 // Reset the G1EvacuationFailureALot counters. Should be called at
853 // the end of an evacuation pause in which an evacuation failure occurred.
854 inline void reset_evacuation_should_fail();
855 #endif // !PRODUCT
856
857 // ("Weak") Reference processing support.
858 //
859 // G1 has 2 instances of the reference processor class. One
860 // (_ref_processor_cm) handles reference object discovery
861 // and subsequent processing during concurrent marking cycles.
862 //
863 // The other (_ref_processor_stw) handles reference object
864 // discovery and processing during full GCs and incremental
865 // evacuation pauses.
866 //
867 // During an incremental pause, reference discovery will be
868 // temporarily disabled for _ref_processor_cm and will be
869 // enabled for _ref_processor_stw. At the end of the evacuation
870 // pause references discovered by _ref_processor_stw will be
871 // processed and discovery will be disabled. The previous
872 // setting for reference object discovery for _ref_processor_cm
873 // will be re-instated.
874 //
875 // At the start of marking:
876 // * Discovery by the CM ref processor is verified to be inactive
877 // and it's discovered lists are empty.
878 // * Discovery by the CM ref processor is then enabled.
879 //
880 // At the end of marking:
881 // * Any references on the CM ref processor's discovered
882 // lists are processed (possibly MT).
883 //
884 // At the start of full GC we:
885 // * Disable discovery by the CM ref processor and
886 // empty CM ref processor's discovered lists
887 // (without processing any entries).
888 // * Verify that the STW ref processor is inactive and it's
889 // discovered lists are empty.
890 // * Temporarily set STW ref processor discovery as single threaded.
891 // * Temporarily clear the STW ref processor's _is_alive_non_header
892 // field.
893 // * Finally enable discovery by the STW ref processor.
894 //
895 // The STW ref processor is used to record any discovered
896 // references during the full GC.
897 //
898 // At the end of a full GC we:
899 // * Enqueue any reference objects discovered by the STW ref processor
900 // that have non-live referents. This has the side-effect of
901 // making the STW ref processor inactive by disabling discovery.
902 // * Verify that the CM ref processor is still inactive
903 // and no references have been placed on it's discovered
904 // lists (also checked as a precondition during initial marking).
905
906 // The (stw) reference processor...
907 ReferenceProcessor* _ref_processor_stw;
908
909 STWGCTimer* _gc_timer_stw;
910
911 G1NewTracer* _gc_tracer_stw;
912
913 // During reference object discovery, the _is_alive_non_header
914 // closure (if non-null) is applied to the referent object to
915 // determine whether the referent is live. If so then the
916 // reference object does not need to be 'discovered' and can
917 // be treated as a regular oop. This has the benefit of reducing
918 // the number of 'discovered' reference objects that need to
919 // be processed.
920 //
921 // Instance of the is_alive closure for embedding into the
922 // STW reference processor as the _is_alive_non_header field.
923 // Supplying a value for the _is_alive_non_header field is
924 // optional but doing so prevents unnecessary additions to
925 // the discovered lists during reference discovery.
926 G1STWIsAliveClosure _is_alive_closure_stw;
927
928 // The (concurrent marking) reference processor...
929 ReferenceProcessor* _ref_processor_cm;
930
931 // Instance of the concurrent mark is_alive closure for embedding
932 // into the Concurrent Marking reference processor as the
933 // _is_alive_non_header field. Supplying a value for the
934 // _is_alive_non_header field is optional but doing so prevents
935 // unnecessary additions to the discovered lists during reference
936 // discovery.
937 G1CMIsAliveClosure _is_alive_closure_cm;
938
939 volatile bool _free_regions_coming;
940
941 public:
942
943 void set_refine_cte_cl_concurrency(bool concurrent);
944
945 RefToScanQueue *task_queue(uint i) const;
946
947 uint num_task_queues() const;
948
949 // A set of cards where updates happened during the GC
950 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
951
952 // Create a G1CollectedHeap with the specified policy.
953 // Must call the initialize method afterwards.
954 // May not return if something goes wrong.
955 G1CollectedHeap(G1CollectorPolicy* policy);
956
957 // Initialize the G1CollectedHeap to have the initial and
958 // maximum sizes and remembered and barrier sets
959 // specified by the policy object.
960 jint initialize();
961
962 virtual void stop();
963
964 // Return the (conservative) maximum heap alignment for any G1 heap
965 static size_t conservative_max_heap_alignment();
966
967 // Does operations required after initialization has been done.
968 void post_initialize();
969
970 // Initialize weak reference processing.
971 void ref_processing_init();
972
973 virtual Name kind() const {
974 return CollectedHeap::G1CollectedHeap;
975 }
976
977 virtual const char* name() const {
978 return "G1";
979 }
980
981 const G1CollectorState* collector_state() const { return &_collector_state; }
982 G1CollectorState* collector_state() { return &_collector_state; }
983
984 // The current policy object for the collector.
985 G1Policy* g1_policy() const { return _g1_policy; }
986
987 const G1CollectionSet* collection_set() const { return &_collection_set; }
988 G1CollectionSet* collection_set() { return &_collection_set; }
989
990 virtual CollectorPolicy* collector_policy() const;
991
992 // Adaptive size policy. No such thing for g1.
993 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
994
995 // The rem set and barrier set.
996 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
997
998 // Try to minimize the remembered set.
999 void scrub_rem_set();
1000
1001 uint get_gc_time_stamp() {
1002 return _gc_time_stamp;
1003 }
1004
1005 inline void reset_gc_time_stamp();
1006
1007 void check_gc_time_stamps() PRODUCT_RETURN;
1008
1009 inline void increment_gc_time_stamp();
1010
1011 // Reset the given region's GC timestamp. If it's starts humongous,
1012 // also reset the GC timestamp of its corresponding
1013 // continues humongous regions too.
1014 void reset_gc_time_stamps(HeapRegion* hr);
1015
1016 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1017 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1018
1019 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1020 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1021
1022 // The shared block offset table array.
1023 G1BlockOffsetTable* bot() const { return _bot; }
1024
1025 // Reference Processing accessors
1026
1027 // The STW reference processor....
1028 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1029
1030 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1031
1032 // The Concurrent Marking reference processor...
1033 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1034
1035 virtual size_t capacity() const;
1036 virtual size_t used() const;
1037 // This should be called when we're not holding the heap lock. The
1038 // result might be a bit inaccurate.
1039 size_t used_unlocked() const;
1040 size_t recalculate_used() const;
1041
1042 // These virtual functions do the actual allocation.
1043 // Some heaps may offer a contiguous region for shared non-blocking
1044 // allocation, via inlined code (by exporting the address of the top and
1045 // end fields defining the extent of the contiguous allocation region.)
1046 // But G1CollectedHeap doesn't yet support this.
1047
1048 virtual bool is_maximal_no_gc() const {
1049 return _hrm.available() == 0;
1050 }
1051
1052 // The current number of regions in the heap.
1053 uint num_regions() const { return _hrm.length(); }
1054
1055 // The max number of regions in the heap.
1056 uint max_regions() const { return _hrm.max_length(); }
1057
1058 // The number of regions that are completely free.
1059 uint num_free_regions() const { return _hrm.num_free_regions(); }
1060
1061 MemoryUsage get_auxiliary_data_memory_usage() const {
1062 return _hrm.get_auxiliary_data_memory_usage();
1063 }
1064
1065 // The number of regions that are not completely free.
1066 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1067
1068 #ifdef ASSERT
1069 bool is_on_master_free_list(HeapRegion* hr) {
1070 return _hrm.is_free(hr);
1071 }
1072 #endif // ASSERT
1073
1074 // Wrapper for the region list operations that can be called from
1075 // methods outside this class.
1076
1077 void secondary_free_list_add(FreeRegionList* list) {
1078 _secondary_free_list.add_ordered(list);
1079 }
1080
1081 void append_secondary_free_list() {
1082 _hrm.insert_list_into_free_list(&_secondary_free_list);
1083 }
1084
1085 void append_secondary_free_list_if_not_empty_with_lock() {
1086 // If the secondary free list looks empty there's no reason to
1087 // take the lock and then try to append it.
1088 if (!_secondary_free_list.is_empty()) {
1089 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1090 append_secondary_free_list();
1091 }
1092 }
1093
1094 inline void old_set_add(HeapRegion* hr);
1095 inline void old_set_remove(HeapRegion* hr);
1096
1097 size_t non_young_capacity_bytes() {
1098 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1099 }
1100
1101 void set_free_regions_coming();
1102 void reset_free_regions_coming();
1103 bool free_regions_coming() { return _free_regions_coming; }
1104 void wait_while_free_regions_coming();
1105
1106 // Determine whether the given region is one that we are using as an
1107 // old GC alloc region.
1108 bool is_old_gc_alloc_region(HeapRegion* hr);
1109
1110 // Perform a collection of the heap; intended for use in implementing
1111 // "System.gc". This probably implies as full a collection as the
1112 // "CollectedHeap" supports.
1113 virtual void collect(GCCause::Cause cause);
1114
1115 virtual bool copy_allocation_context_stats(const jint* contexts,
1116 jlong* totals,
1117 jbyte* accuracy,
1118 jint len);
1119
1120 // True iff an evacuation has failed in the most-recent collection.
1121 bool evacuation_failed() { return _evacuation_failed; }
1122
1123 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1124 void prepend_to_freelist(FreeRegionList* list);
1125 void decrement_summary_bytes(size_t bytes);
1126
1127 virtual bool is_in(const void* p) const;
1128 #ifdef ASSERT
1129 // Returns whether p is in one of the available areas of the heap. Slow but
1130 // extensive version.
1131 bool is_in_exact(const void* p) const;
1132 #endif
1133
1134 // Return "TRUE" iff the given object address is within the collection
1135 // set. Assumes that the reference points into the heap.
1136 inline bool is_in_cset(const HeapRegion *hr);
1137 inline bool is_in_cset(oop obj);
1138
1139 inline bool is_in_cset_or_humongous(const oop obj);
1140
1141 private:
1142 // This array is used for a quick test on whether a reference points into
1143 // the collection set or not. Each of the array's elements denotes whether the
1144 // corresponding region is in the collection set or not.
1145 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1146
1147 public:
1148
1149 inline InCSetState in_cset_state(const oop obj);
1150
1151 // Return "TRUE" iff the given object address is in the reserved
1152 // region of g1.
1153 bool is_in_g1_reserved(const void* p) const {
1154 return _hrm.reserved().contains(p);
1155 }
1156
1157 // Returns a MemRegion that corresponds to the space that has been
1158 // reserved for the heap
1159 MemRegion g1_reserved() const {
1160 return _hrm.reserved();
1161 }
1162
1163 virtual bool is_in_closed_subset(const void* p) const;
1164
1165 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1166 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1167 }
1168
1169 // Iteration functions.
1170
1171 // Iterate over all objects, calling "cl.do_object" on each.
1172 virtual void object_iterate(ObjectClosure* cl);
1173
1174 virtual void safe_object_iterate(ObjectClosure* cl) {
1175 object_iterate(cl);
1176 }
1177
1178 // Iterate over heap regions, in address order, terminating the
1179 // iteration early if the "doHeapRegion" method returns "true".
1180 void heap_region_iterate(HeapRegionClosure* blk) const;
1181
1182 // Return the region with the given index. It assumes the index is valid.
1183 inline HeapRegion* region_at(uint index) const;
1184
1185 // Return the next region (by index) that is part of the same
1186 // humongous object that hr is part of.
1187 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1188
1189 // Calculate the region index of the given address. Given address must be
1190 // within the heap.
1191 inline uint addr_to_region(HeapWord* addr) const;
1192
1193 inline HeapWord* bottom_addr_for_region(uint index) const;
1194
1195 // Iterate over the heap regions in parallel. Assumes that this will be called
1196 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1197 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1198 // to each of the regions, by attempting to claim the region using the
1199 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1200 // region. The concurrent argument should be set to true if iteration is
1201 // performed concurrently, during which no assumptions are made for consistent
1202 // attributes of the heap regions (as they might be modified while iterating).
1203 void heap_region_par_iterate(HeapRegionClosure* cl,
1204 uint worker_id,
1205 HeapRegionClaimer* hrclaimer,
1206 bool concurrent = false) const;
1207
1208 // Iterate over the regions (if any) in the current collection set.
1209 void collection_set_iterate(HeapRegionClosure* blk);
1210
1211 // Iterate over the regions (if any) in the current collection set. Starts the
1212 // iteration over the entire collection set so that the start regions of a given
1213 // worker id over the set active_workers are evenly spread across the set of
1214 // collection set regions.
1215 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1216
1217 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1218
1219 // Returns the HeapRegion that contains addr. addr must not be NULL.
1220 template <class T>
1221 inline HeapRegion* heap_region_containing(const T addr) const;
1222
1223 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1224 // each address in the (reserved) heap is a member of exactly
1225 // one block. The defining characteristic of a block is that it is
1226 // possible to find its size, and thus to progress forward to the next
1227 // block. (Blocks may be of different sizes.) Thus, blocks may
1228 // represent Java objects, or they might be free blocks in a
1229 // free-list-based heap (or subheap), as long as the two kinds are
1230 // distinguishable and the size of each is determinable.
1231
1232 // Returns the address of the start of the "block" that contains the
1233 // address "addr". We say "blocks" instead of "object" since some heaps
1234 // may not pack objects densely; a chunk may either be an object or a
1235 // non-object.
1236 virtual HeapWord* block_start(const void* addr) const;
1237
1238 // Requires "addr" to be the start of a chunk, and returns its size.
1239 // "addr + size" is required to be the start of a new chunk, or the end
1240 // of the active area of the heap.
1241 virtual size_t block_size(const HeapWord* addr) const;
1242
1243 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1244 // the block is an object.
1245 virtual bool block_is_obj(const HeapWord* addr) const;
1246
1247 // Section on thread-local allocation buffers (TLABs)
1248 // See CollectedHeap for semantics.
1249
1250 bool supports_tlab_allocation() const;
1251 size_t tlab_capacity(Thread* ignored) const;
1252 size_t tlab_used(Thread* ignored) const;
1253 size_t max_tlab_size() const;
1254 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1255
1256 // Can a compiler initialize a new object without store barriers?
1257 // This permission only extends from the creation of a new object
1258 // via a TLAB up to the first subsequent safepoint. If such permission
1259 // is granted for this heap type, the compiler promises to call
1260 // defer_store_barrier() below on any slow path allocation of
1261 // a new object for which such initializing store barriers will
1262 // have been elided. G1, like CMS, allows this, but should be
1263 // ready to provide a compensating write barrier as necessary
1264 // if that storage came out of a non-young region. The efficiency
1265 // of this implementation depends crucially on being able to
1266 // answer very efficiently in constant time whether a piece of
1267 // storage in the heap comes from a young region or not.
1268 // See ReduceInitialCardMarks.
1269 virtual bool can_elide_tlab_store_barriers() const {
1270 return true;
1271 }
1272
1273 virtual bool card_mark_must_follow_store() const {
1274 return true;
1275 }
1276
1277 inline bool is_in_young(const oop obj);
1278
1279 virtual bool is_scavengable(const void* addr);
1280
1281 // We don't need barriers for initializing stores to objects
1282 // in the young gen: for the SATB pre-barrier, there is no
1283 // pre-value that needs to be remembered; for the remembered-set
1284 // update logging post-barrier, we don't maintain remembered set
1285 // information for young gen objects.
1286 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1287
1288 // Returns "true" iff the given word_size is "very large".
1289 static bool is_humongous(size_t word_size) {
1290 // Note this has to be strictly greater-than as the TLABs
1291 // are capped at the humongous threshold and we want to
1292 // ensure that we don't try to allocate a TLAB as
1293 // humongous and that we don't allocate a humongous
1294 // object in a TLAB.
1295 return word_size > _humongous_object_threshold_in_words;
1296 }
1297
1298 // Returns the humongous threshold for a specific region size
1299 static size_t humongous_threshold_for(size_t region_size) {
1300 return (region_size / 2);
1301 }
1302
1303 // Returns the number of regions the humongous object of the given word size
1304 // requires.
1305 static size_t humongous_obj_size_in_regions(size_t word_size);
1306
1307 // Print the maximum heap capacity.
1308 virtual size_t max_capacity() const;
1309
1310 virtual jlong millis_since_last_gc();
1311
1312
1313 // Convenience function to be used in situations where the heap type can be
1314 // asserted to be this type.
1315 static G1CollectedHeap* heap();
1316
1317 void set_region_short_lived_locked(HeapRegion* hr);
1318 // add appropriate methods for any other surv rate groups
1319
1320 const G1SurvivorRegions* survivor() const { return &_survivor; }
1321
1322 uint survivor_regions_count() const {
1323 return _survivor.length();
1324 }
1325
1326 uint eden_regions_count() const {
1327 return _eden.length();
1328 }
1329
1330 uint young_regions_count() const {
1331 return _eden.length() + _survivor.length();
1332 }
1333
1334 uint old_regions_count() const { return _old_set.length(); }
1335
1336 uint humongous_regions_count() const { return _humongous_set.length(); }
1337
1338 #ifdef ASSERT
1339 bool check_young_list_empty();
1340 #endif
1341
1342 // *** Stuff related to concurrent marking. It's not clear to me that so
1343 // many of these need to be public.
1344
1345 // The functions below are helper functions that a subclass of
1346 // "CollectedHeap" can use in the implementation of its virtual
1347 // functions.
1348 // This performs a concurrent marking of the live objects in a
1349 // bitmap off to the side.
1350 void doConcurrentMark();
1351
1352 bool isMarkedPrev(oop obj) const;
1353 bool isMarkedNext(oop obj) const;
1354
1355 // Determine if an object is dead, given the object and also
1356 // the region to which the object belongs. An object is dead
1357 // iff a) it was not allocated since the last mark, b) it
1358 // is not marked, and c) it is not in an archive region.
1359 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1360 return
1361 !hr->obj_allocated_since_prev_marking(obj) &&
1362 !isMarkedPrev(obj) &&
1363 !hr->is_archive();
1364 }
1365
1366 // This function returns true when an object has been
1367 // around since the previous marking and hasn't yet
1368 // been marked during this marking, and is not in an archive region.
1369 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1370 return
1371 !hr->obj_allocated_since_next_marking(obj) &&
1372 !isMarkedNext(obj) &&
1373 !hr->is_archive();
1374 }
1375
1376 // Determine if an object is dead, given only the object itself.
1377 // This will find the region to which the object belongs and
1378 // then call the region version of the same function.
1379
1380 // Added if it is NULL it isn't dead.
1381
1382 inline bool is_obj_dead(const oop obj) const;
1383
1384 inline bool is_obj_ill(const oop obj) const;
1385
1386 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1387
1388 // Refinement
1389
1390 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1391
1392 // Optimized nmethod scanning support routines
1393
1394 // Register the given nmethod with the G1 heap.
1395 virtual void register_nmethod(nmethod* nm);
1396
1397 // Unregister the given nmethod from the G1 heap.
1398 virtual void unregister_nmethod(nmethod* nm);
1399
1400 // Free up superfluous code root memory.
1401 void purge_code_root_memory();
1402
1403 // Rebuild the strong code root lists for each region
1404 // after a full GC.
1405 void rebuild_strong_code_roots();
1406
1407 // Partial cleaning used when class unloading is disabled.
1408 // Let the caller choose what structures to clean out:
1409 // - StringTable
1410 // - SymbolTable
1411 // - StringDeduplication structures
1412 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1413
1414 // Complete cleaning used when class unloading is enabled.
1415 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1416 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1417
1418 // Redirty logged cards in the refinement queue.
1419 void redirty_logged_cards();
1420 // Verification
1421
1422 // Perform any cleanup actions necessary before allowing a verification.
1423 virtual void prepare_for_verify();
1424
1425 // Perform verification.
1426
1427 // vo == UsePrevMarking -> use "prev" marking information,
1428 // vo == UseNextMarking -> use "next" marking information
1429 // vo == UseMarkWord -> use the mark word in the object header
1430 //
1431 // NOTE: Only the "prev" marking information is guaranteed to be
1432 // consistent most of the time, so most calls to this should use
1433 // vo == UsePrevMarking.
1434 // Currently, there is only one case where this is called with
1435 // vo == UseNextMarking, which is to verify the "next" marking
1436 // information at the end of remark.
1437 // Currently there is only one place where this is called with
1438 // vo == UseMarkWord, which is to verify the marking during a
1439 // full GC.
1440 void verify(VerifyOption vo);
1441
1442 // WhiteBox testing support.
1443 virtual bool supports_concurrent_phase_control() const;
1444 virtual const char* const* concurrent_phases() const;
1445 virtual bool request_concurrent_phase(const char* phase);
1446
1447 // The methods below are here for convenience and dispatch the
1448 // appropriate method depending on value of the given VerifyOption
1449 // parameter. The values for that parameter, and their meanings,
1450 // are the same as those above.
1451
1452 bool is_obj_dead_cond(const oop obj,
1453 const HeapRegion* hr,
1454 const VerifyOption vo) const;
1455
1456 bool is_obj_dead_cond(const oop obj,
1457 const VerifyOption vo) const;
1458
1459 G1HeapSummary create_g1_heap_summary();
1460 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1461
1462 // Printing
1463 private:
1464 void print_heap_regions() const;
1465 void print_regions_on(outputStream* st) const;
1466
1467 public:
1468 virtual void print_on(outputStream* st) const;
1469 virtual void print_extended_on(outputStream* st) const;
1470 virtual void print_on_error(outputStream* st) const;
1471
1472 virtual void print_gc_threads_on(outputStream* st) const;
1473 virtual void gc_threads_do(ThreadClosure* tc) const;
1474
1475 // Override
1476 void print_tracing_info() const;
1477
1478 // The following two methods are helpful for debugging RSet issues.
1479 void print_cset_rsets() PRODUCT_RETURN;
1480 void print_all_rsets() PRODUCT_RETURN;
1481
1482 public:
1483 size_t pending_card_num();
1484
1485 protected:
1486 size_t _max_heap_capacity;
1487 };
1488
1489 class G1ParEvacuateFollowersClosure : public VoidClosure {
1490 private:
1491 double _start_term;
1492 double _term_time;
1493 size_t _term_attempts;
1494
1495 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1496 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1497 protected:
1498 G1CollectedHeap* _g1h;
1499 G1ParScanThreadState* _par_scan_state;
1500 RefToScanQueueSet* _queues;
1501 ParallelTaskTerminator* _terminator;
1502
1503 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1504 RefToScanQueueSet* queues() { return _queues; }
1505 ParallelTaskTerminator* terminator() { return _terminator; }
1506
1507 public:
1508 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1509 G1ParScanThreadState* par_scan_state,
1510 RefToScanQueueSet* queues,
1511 ParallelTaskTerminator* terminator)
1512 : _g1h(g1h), _par_scan_state(par_scan_state),
1513 _queues(queues), _terminator(terminator),
1514 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1515
1516 void do_void();
1517
1518 double term_time() const { return _term_time; }
1519 size_t term_attempts() const { return _term_attempts; }
1520
1521 private:
1522 inline bool offer_termination();
1523 };
1524
1525 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP