1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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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/concurrentMark.hpp"
29 #include "gc/g1/evacuationInfo.hpp"
30 #include "gc/g1/g1AllocationContext.hpp"
31 #include "gc/g1/g1BiasedArray.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1HRPrinter.hpp"
34 #include "gc/g1/g1InCSetState.hpp"
35 #include "gc/g1/g1MonitoringSupport.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
38 #include "gc/g1/g1YCTypes.hpp"
39 #include "gc/g1/hSpaceCounters.hpp"
40 #include "gc/g1/heapRegionManager.hpp"
41 #include "gc/g1/heapRegionSet.hpp"
42 #include "gc/g1/youngList.hpp"
43 #include "gc/shared/barrierSet.hpp"
44 #include "gc/shared/collectedHeap.hpp"
45 #include "gc/shared/plab.hpp"
46 #include "memory/memRegion.hpp"
47 #include "utilities/stack.hpp"
48
49 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
50 // It uses the "Garbage First" heap organization and algorithm, which
51 // may combine concurrent marking with parallel, incremental compaction of
52 // heap subsets that will yield large amounts of garbage.
53
54 // Forward declarations
55 class HeapRegion;
56 class HRRSCleanupTask;
57 class GenerationSpec;
58 class OopsInHeapRegionClosure;
59 class G1ParScanThreadState;
60 class G1ParScanThreadStateSet;
61 class G1KlassScanClosure;
62 class G1ParScanThreadState;
63 class ObjectClosure;
64 class SpaceClosure;
65 class CompactibleSpaceClosure;
66 class Space;
67 class G1CollectorPolicy;
68 class G1RemSet;
69 class HeapRegionRemSetIterator;
70 class ConcurrentMark;
71 class ConcurrentMarkThread;
72 class ConcurrentG1Refine;
73 class ConcurrentGCTimer;
74 class GenerationCounters;
75 class STWGCTimer;
76 class G1NewTracer;
77 class G1OldTracer;
78 class EvacuationFailedInfo;
79 class nmethod;
80 class Ticks;
81 class WorkGang;
82 class G1Allocator;
83 class G1ArchiveAllocator;
84
85 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
86 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
87
88 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
89 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
90
91 // The G1 STW is alive closure.
92 // An instance is embedded into the G1CH and used as the
93 // (optional) _is_alive_non_header closure in the STW
94 // reference processor. It is also extensively used during
95 // reference processing during STW evacuation pauses.
96 class G1STWIsAliveClosure: public BoolObjectClosure {
97 G1CollectedHeap* _g1;
98 public:
99 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
100 bool do_object_b(oop p);
101 };
102
103 class RefineCardTableEntryClosure;
104
105 class G1RegionMappingChangedListener : public G1MappingChangedListener {
106 private:
107 void reset_from_card_cache(uint start_idx, size_t num_regions);
108 public:
109 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
110 };
111
112 class G1CollectedHeap : public CollectedHeap {
113 friend class VM_CollectForMetadataAllocation;
114 friend class VM_G1CollectForAllocation;
115 friend class VM_G1CollectFull;
116 friend class VM_G1IncCollectionPause;
117 friend class VMStructs;
118 friend class MutatorAllocRegion;
119 friend class G1GCAllocRegion;
120
121 // Closures used in implementation.
122 friend class G1ParScanThreadState;
123 friend class G1ParScanThreadStateSet;
124 friend class G1ParTask;
125 friend class G1PLABAllocator;
126 friend class G1PrepareCompactClosure;
127
128 // Other related classes.
129 friend class HeapRegionClaimer;
130
131 // Testing classes.
132 friend class G1CheckCSetFastTableClosure;
133
134 private:
135 WorkGang* _workers;
136
137 static size_t _humongous_object_threshold_in_words;
138
139 // The secondary free list which contains regions that have been
140 // freed up during the cleanup process. This will be appended to
141 // the master free list when appropriate.
142 FreeRegionList _secondary_free_list;
143
144 // It keeps track of the old regions.
145 HeapRegionSet _old_set;
146
147 // It keeps track of the humongous regions.
148 HeapRegionSet _humongous_set;
149
150 void eagerly_reclaim_humongous_regions();
151
152 // The number of regions we could create by expansion.
153 uint _expansion_regions;
154
155 // The block offset table for the G1 heap.
156 G1BlockOffsetSharedArray* _bot_shared;
157
158 // Tears down the region sets / lists so that they are empty and the
159 // regions on the heap do not belong to a region set / list. The
160 // only exception is the humongous set which we leave unaltered. If
161 // free_list_only is true, it will only tear down the master free
162 // list. It is called before a Full GC (free_list_only == false) or
163 // before heap shrinking (free_list_only == true).
164 void tear_down_region_sets(bool free_list_only);
165
166 // Rebuilds the region sets / lists so that they are repopulated to
167 // reflect the contents of the heap. The only exception is the
168 // humongous set which was not torn down in the first place. If
169 // free_list_only is true, it will only rebuild the master free
170 // list. It is called after a Full GC (free_list_only == false) or
171 // after heap shrinking (free_list_only == true).
172 void rebuild_region_sets(bool free_list_only);
173
174 // Callback for region mapping changed events.
175 G1RegionMappingChangedListener _listener;
176
177 // The sequence of all heap regions in the heap.
178 HeapRegionManager _hrm;
179
180 // Manages all allocations with regions except humongous object allocations.
181 G1Allocator* _allocator;
182
183 // Outside of GC pauses, the number of bytes used in all regions other
184 // than the current allocation region(s).
185 size_t _summary_bytes_used;
186
187 void increase_used(size_t bytes);
188 void decrease_used(size_t bytes);
189
190 void set_used(size_t bytes);
191
192 // Class that handles archive allocation ranges.
193 G1ArchiveAllocator* _archive_allocator;
194
195 // Statistics for each allocation context
196 AllocationContextStats _allocation_context_stats;
197
198 // GC allocation statistics policy for survivors.
199 G1EvacStats _survivor_evac_stats;
200
201 // GC allocation statistics policy for tenured objects.
202 G1EvacStats _old_evac_stats;
203
204 // It specifies whether we should attempt to expand the heap after a
205 // region allocation failure. If heap expansion fails we set this to
206 // false so that we don't re-attempt the heap expansion (it's likely
207 // that subsequent expansion attempts will also fail if one fails).
208 // Currently, it is only consulted during GC and it's reset at the
209 // start of each GC.
210 bool _expand_heap_after_alloc_failure;
211
212 // Helper for monitoring and management support.
213 G1MonitoringSupport* _g1mm;
214
215 // Records whether the region at the given index is (still) a
216 // candidate for eager reclaim. Only valid for humongous start
217 // regions; other regions have unspecified values. Humongous start
218 // regions are initialized at start of collection pause, with
219 // candidates removed from the set as they are found reachable from
220 // roots or the young generation.
221 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
222 protected:
223 bool default_value() const { return false; }
224 public:
225 void clear() { G1BiasedMappedArray<bool>::clear(); }
226 void set_candidate(uint region, bool value) {
227 set_by_index(region, value);
228 }
229 bool is_candidate(uint region) {
230 return get_by_index(region);
231 }
232 };
233
234 HumongousReclaimCandidates _humongous_reclaim_candidates;
235 // Stores whether during humongous object registration we found candidate regions.
236 // If not, we can skip a few steps.
237 bool _has_humongous_reclaim_candidates;
238
239 volatile unsigned _gc_time_stamp;
240
241 G1HRPrinter _hr_printer;
242
243 // It decides whether an explicit GC should start a concurrent cycle
244 // instead of doing a STW GC. Currently, a concurrent cycle is
245 // explicitly started if:
246 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
247 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
248 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
249 // (d) cause == _g1_humongous_allocation
250 bool should_do_concurrent_full_gc(GCCause::Cause cause);
251
252 // indicates whether we are in young or mixed GC mode
253 G1CollectorState _collector_state;
254
255 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
256 // concurrent cycles) we have started.
257 volatile uint _old_marking_cycles_started;
258
259 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
260 // concurrent cycles) we have completed.
261 volatile uint _old_marking_cycles_completed;
262
263 bool _heap_summary_sent;
264
265 // This is a non-product method that is helpful for testing. It is
266 // called at the end of a GC and artificially expands the heap by
267 // allocating a number of dead regions. This way we can induce very
268 // frequent marking cycles and stress the cleanup / concurrent
269 // cleanup code more (as all the regions that will be allocated by
270 // this method will be found dead by the marking cycle).
271 void allocate_dummy_regions() PRODUCT_RETURN;
272
273 // Clear RSets after a compaction. It also resets the GC time stamps.
274 void clear_rsets_post_compaction();
275
276 // If the HR printer is active, dump the state of the regions in the
277 // heap after a compaction.
278 void print_hrm_post_compaction();
279
280 // Create a memory mapper for auxiliary data structures of the given size and
281 // translation factor.
282 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
283 size_t size,
284 size_t translation_factor);
285
286 double verify(bool guard, const char* msg);
287 void verify_before_gc();
288 void verify_after_gc();
289
290 void log_gc_footer(double pause_time_counter);
291
292 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
293
294 // These are macros so that, if the assert fires, we get the correct
295 // line number, file, etc.
296
297 #define heap_locking_asserts_params(_extra_message_) \
298 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
299 (_extra_message_), \
300 BOOL_TO_STR(Heap_lock->owned_by_self()), \
301 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
302 BOOL_TO_STR(Thread::current()->is_VM_thread())
303
304 #define assert_heap_locked() \
305 do { \
306 assert(Heap_lock->owned_by_self(), \
307 heap_locking_asserts_params("should be holding the Heap_lock")); \
308 } while (0)
309
310 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
311 do { \
312 assert(Heap_lock->owned_by_self() || \
313 (SafepointSynchronize::is_at_safepoint() && \
314 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
315 heap_locking_asserts_params("should be holding the Heap_lock or " \
316 "should be at a safepoint")); \
317 } while (0)
318
319 #define assert_heap_locked_and_not_at_safepoint() \
320 do { \
321 assert(Heap_lock->owned_by_self() && \
322 !SafepointSynchronize::is_at_safepoint(), \
323 heap_locking_asserts_params("should be holding the Heap_lock and " \
324 "should not be at a safepoint")); \
325 } while (0)
326
327 #define assert_heap_not_locked() \
328 do { \
329 assert(!Heap_lock->owned_by_self(), \
330 heap_locking_asserts_params("should not be holding the Heap_lock")); \
331 } while (0)
332
333 #define assert_heap_not_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 not be holding the Heap_lock and " \
338 "should not be at a safepoint")); \
339 } while (0)
340
341 #define assert_at_safepoint(_should_be_vm_thread_) \
342 do { \
343 assert(SafepointSynchronize::is_at_safepoint() && \
344 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
345 heap_locking_asserts_params("should be at a safepoint")); \
346 } while (0)
347
348 #define assert_not_at_safepoint() \
349 do { \
350 assert(!SafepointSynchronize::is_at_safepoint(), \
351 heap_locking_asserts_params("should not be at a safepoint")); \
352 } while (0)
353
354 protected:
355
356 // The young region list.
357 YoungList* _young_list;
358
359 // The current policy object for the collector.
360 G1CollectorPolicy* _g1_policy;
361
362 // This is the second level of trying to allocate a new region. If
363 // new_region() didn't find a region on the free_list, this call will
364 // check whether there's anything available on the
365 // secondary_free_list and/or wait for more regions to appear on
366 // that list, if _free_regions_coming is set.
367 HeapRegion* new_region_try_secondary_free_list(bool is_old);
368
369 // Try to allocate a single non-humongous HeapRegion sufficient for
370 // an allocation of the given word_size. If do_expand is true,
371 // attempt to expand the heap if necessary to satisfy the allocation
372 // request. If the region is to be used as an old region or for a
373 // humongous object, set is_old to true. If not, to false.
374 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
375
376 // Initialize a contiguous set of free regions of length num_regions
377 // and starting at index first so that they appear as a single
378 // humongous region.
379 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
380 uint num_regions,
381 size_t word_size,
382 AllocationContext_t context);
383
384 // Attempt to allocate a humongous object of the given size. Return
385 // NULL if unsuccessful.
386 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
387
388 // The following two methods, allocate_new_tlab() and
389 // mem_allocate(), are the two main entry points from the runtime
390 // into the G1's allocation routines. They have the following
391 // assumptions:
392 //
393 // * They should both be called outside safepoints.
394 //
395 // * They should both be called without holding the Heap_lock.
396 //
397 // * All allocation requests for new TLABs should go to
398 // allocate_new_tlab().
399 //
400 // * All non-TLAB allocation requests should go to mem_allocate().
401 //
402 // * If either call cannot satisfy the allocation request using the
403 // current allocating region, they will try to get a new one. If
404 // this fails, they will attempt to do an evacuation pause and
405 // retry the allocation.
406 //
407 // * If all allocation attempts fail, even after trying to schedule
408 // an evacuation pause, allocate_new_tlab() will return NULL,
409 // whereas mem_allocate() will attempt a heap expansion and/or
410 // schedule a Full GC.
411 //
412 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
413 // should never be called with word_size being humongous. All
414 // humongous allocation requests should go to mem_allocate() which
415 // will satisfy them with a special path.
416
417 virtual HeapWord* allocate_new_tlab(size_t word_size);
418
419 virtual HeapWord* mem_allocate(size_t word_size,
420 bool* gc_overhead_limit_was_exceeded);
421
422 // The following three methods take a gc_count_before_ret
423 // parameter which is used to return the GC count if the method
424 // returns NULL. Given that we are required to read the GC count
425 // while holding the Heap_lock, and these paths will take the
426 // Heap_lock at some point, it's easier to get them to read the GC
427 // count while holding the Heap_lock before they return NULL instead
428 // of the caller (namely: mem_allocate()) having to also take the
429 // Heap_lock just to read the GC count.
430
431 // First-level mutator allocation attempt: try to allocate out of
432 // the mutator alloc region without taking the Heap_lock. This
433 // should only be used for non-humongous allocations.
434 inline HeapWord* attempt_allocation(size_t word_size,
435 uint* gc_count_before_ret,
436 uint* gclocker_retry_count_ret);
437
438 // Second-level mutator allocation attempt: take the Heap_lock and
439 // retry the allocation attempt, potentially scheduling a GC
440 // pause. This should only be used for non-humongous allocations.
441 HeapWord* attempt_allocation_slow(size_t word_size,
442 AllocationContext_t context,
443 uint* gc_count_before_ret,
444 uint* gclocker_retry_count_ret);
445
446 // Takes the Heap_lock and attempts a humongous allocation. It can
447 // potentially schedule a GC pause.
448 HeapWord* attempt_allocation_humongous(size_t word_size,
449 uint* gc_count_before_ret,
450 uint* gclocker_retry_count_ret);
451
452 // Allocation attempt that should be called during safepoints (e.g.,
453 // at the end of a successful GC). expect_null_mutator_alloc_region
454 // specifies whether the mutator alloc region is expected to be NULL
455 // or not.
456 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
457 AllocationContext_t context,
458 bool expect_null_mutator_alloc_region);
459
460 // These methods are the "callbacks" from the G1AllocRegion class.
461
462 // For mutator alloc regions.
463 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
464 void retire_mutator_alloc_region(HeapRegion* alloc_region,
465 size_t allocated_bytes);
466
467 // For GC alloc regions.
468 HeapRegion* new_gc_alloc_region(size_t word_size, uint count,
469 InCSetState dest);
470 void retire_gc_alloc_region(HeapRegion* alloc_region,
471 size_t allocated_bytes, InCSetState dest);
472
473 // - if explicit_gc is true, the GC is for a System.gc() or a heap
474 // inspection request and should collect the entire heap
475 // - if clear_all_soft_refs is true, all soft references should be
476 // cleared during the GC
477 // - if explicit_gc is false, word_size describes the allocation that
478 // the GC should attempt (at least) to satisfy
479 // - it returns false if it is unable to do the collection due to the
480 // GC locker being active, true otherwise
481 bool do_collection(bool explicit_gc,
482 bool clear_all_soft_refs,
483 size_t word_size);
484
485 // Callback from VM_G1CollectFull operation.
486 // Perform a full collection.
487 virtual void do_full_collection(bool clear_all_soft_refs);
488
489 // Resize the heap if necessary after a full collection. If this is
490 // after a collect-for allocation, "word_size" is the allocation size,
491 // and will be considered part of the used portion of the heap.
492 void resize_if_necessary_after_full_collection(size_t word_size);
493
494 // Callback from VM_G1CollectForAllocation operation.
495 // This function does everything necessary/possible to satisfy a
496 // failed allocation request (including collection, expansion, etc.)
497 HeapWord* satisfy_failed_allocation(size_t word_size,
498 AllocationContext_t context,
499 bool* succeeded);
500 private:
501 // Helper method for satisfy_failed_allocation()
502 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
503 AllocationContext_t context,
504 bool do_gc,
505 bool clear_all_soft_refs,
506 bool expect_null_mutator_alloc_region,
507 bool* gc_succeeded);
508
509 protected:
510 // Attempting to expand the heap sufficiently
511 // to support an allocation of the given "word_size". If
512 // successful, perform the allocation and return the address of the
513 // allocated block, or else "NULL".
514 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
515
516 // Process any reference objects discovered during
517 // an incremental evacuation pause.
518 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
519
520 // Enqueue any remaining discovered references
521 // after processing.
522 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
523
524 public:
525 WorkGang* workers() const { return _workers; }
526
527 G1Allocator* allocator() {
528 return _allocator;
529 }
530
531 G1MonitoringSupport* g1mm() {
532 assert(_g1mm != NULL, "should have been initialized");
533 return _g1mm;
534 }
535
536 // Expand the garbage-first heap by at least the given size (in bytes!).
537 // Returns true if the heap was expanded by the requested amount;
538 // false otherwise.
539 // (Rounds up to a HeapRegion boundary.)
540 bool expand(size_t expand_bytes, double* expand_time_ms = NULL);
541
542 // Returns the PLAB statistics for a given destination.
543 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
544
545 // Determines PLAB size for a given destination.
546 inline size_t desired_plab_sz(InCSetState dest);
547
548 inline AllocationContextStats& allocation_context_stats();
549
550 // Do anything common to GC's.
551 void gc_prologue(bool full);
552 void gc_epilogue(bool full);
553
554 // Modify the reclaim candidate set and test for presence.
555 // These are only valid for starts_humongous regions.
556 inline void set_humongous_reclaim_candidate(uint region, bool value);
557 inline bool is_humongous_reclaim_candidate(uint region);
558
559 // Remove from the reclaim candidate set. Also remove from the
560 // collection set so that later encounters avoid the slow path.
561 inline void set_humongous_is_live(oop obj);
562
563 // Register the given region to be part of the collection set.
564 inline void register_humongous_region_with_cset(uint index);
565 // Register regions with humongous objects (actually on the start region) in
566 // the in_cset_fast_test table.
567 void register_humongous_regions_with_cset();
568 // We register a region with the fast "in collection set" test. We
569 // simply set to true the array slot corresponding to this region.
570 void register_young_region_with_cset(HeapRegion* r) {
571 _in_cset_fast_test.set_in_young(r->hrm_index());
572 }
573 void register_old_region_with_cset(HeapRegion* r) {
574 _in_cset_fast_test.set_in_old(r->hrm_index());
575 }
576 void clear_in_cset(const HeapRegion* hr) {
577 _in_cset_fast_test.clear(hr);
578 }
579
580 void clear_cset_fast_test() {
581 _in_cset_fast_test.clear();
582 }
583
584 // This is called at the start of either a concurrent cycle or a Full
585 // GC to update the number of old marking cycles started.
586 void increment_old_marking_cycles_started();
587
588 // This is called at the end of either a concurrent cycle or a Full
589 // GC to update the number of old marking cycles completed. Those two
590 // can happen in a nested fashion, i.e., we start a concurrent
591 // cycle, a Full GC happens half-way through it which ends first,
592 // and then the cycle notices that a Full GC happened and ends
593 // too. The concurrent parameter is a boolean to help us do a bit
594 // tighter consistency checking in the method. If concurrent is
595 // false, the caller is the inner caller in the nesting (i.e., the
596 // Full GC). If concurrent is true, the caller is the outer caller
597 // in this nesting (i.e., the concurrent cycle). Further nesting is
598 // not currently supported. The end of this call also notifies
599 // the FullGCCount_lock in case a Java thread is waiting for a full
600 // GC to happen (e.g., it called System.gc() with
601 // +ExplicitGCInvokesConcurrent).
602 void increment_old_marking_cycles_completed(bool concurrent);
603
604 uint old_marking_cycles_completed() {
605 return _old_marking_cycles_completed;
606 }
607
608 void register_concurrent_cycle_start(const Ticks& start_time);
609 void register_concurrent_cycle_end();
610 void trace_heap_after_concurrent_cycle();
611
612 G1HRPrinter* hr_printer() { return &_hr_printer; }
613
614 // Allocates a new heap region instance.
615 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
616
617 // Allocate the highest free region in the reserved heap. This will commit
618 // regions as necessary.
619 HeapRegion* alloc_highest_free_region();
620
621 // Frees a non-humongous region by initializing its contents and
622 // adding it to the free list that's passed as a parameter (this is
623 // usually a local list which will be appended to the master free
624 // list later). The used bytes of freed regions are accumulated in
625 // pre_used. If par is true, the region's RSet will not be freed
626 // up. The assumption is that this will be done later.
627 // The locked parameter indicates if the caller has already taken
628 // care of proper synchronization. This may allow some optimizations.
629 void free_region(HeapRegion* hr,
630 FreeRegionList* free_list,
631 bool par,
632 bool locked = false);
633
634 // It dirties the cards that cover the block so that the post
635 // write barrier never queues anything when updating objects on this
636 // block. It is assumed (and in fact we assert) that the block
637 // belongs to a young region.
638 inline void dirty_young_block(HeapWord* start, size_t word_size);
639
640 // Frees a humongous region by collapsing it into individual regions
641 // and calling free_region() for each of them. The freed regions
642 // will be added to the free list that's passed as a parameter (this
643 // is usually a local list which will be appended to the master free
644 // list later). The used bytes of freed regions are accumulated in
645 // pre_used. If par is true, the region's RSet will not be freed
646 // up. The assumption is that this will be done later.
647 void free_humongous_region(HeapRegion* hr,
648 FreeRegionList* free_list,
649 bool par);
650
651 // Facility for allocating in 'archive' regions in high heap memory and
652 // recording the allocated ranges. These should all be called from the
653 // VM thread at safepoints, without the heap lock held. They can be used
654 // to create and archive a set of heap regions which can be mapped at the
655 // same fixed addresses in a subsequent JVM invocation.
656 void begin_archive_alloc_range();
657
658 // Check if the requested size would be too large for an archive allocation.
659 bool is_archive_alloc_too_large(size_t word_size);
660
661 // Allocate memory of the requested size from the archive region. This will
662 // return NULL if the size is too large or if no memory is available. It
663 // does not trigger a garbage collection.
664 HeapWord* archive_mem_allocate(size_t word_size);
665
666 // Optionally aligns the end address and returns the allocated ranges in
667 // an array of MemRegions in order of ascending addresses.
668 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
669 size_t end_alignment_in_bytes = 0);
670
671 // Facility for allocating a fixed range within the heap and marking
672 // the containing regions as 'archive'. For use at JVM init time, when the
673 // caller may mmap archived heap data at the specified range(s).
674 // Verify that the MemRegions specified in the argument array are within the
675 // reserved heap.
676 bool check_archive_addresses(MemRegion* range, size_t count);
677
678 // Commit the appropriate G1 regions containing the specified MemRegions
679 // and mark them as 'archive' regions. The regions in the array must be
680 // non-overlapping and in order of ascending address.
681 bool alloc_archive_regions(MemRegion* range, size_t count);
682
683 // Insert any required filler objects in the G1 regions around the specified
684 // ranges to make the regions parseable. This must be called after
685 // alloc_archive_regions, and after class loading has occurred.
686 void fill_archive_regions(MemRegion* range, size_t count);
687
688 // For each of the specified MemRegions, uncommit the containing G1 regions
689 // which had been allocated by alloc_archive_regions. This should be called
690 // rather than fill_archive_regions at JVM init time if the archive file
691 // mapping failed, with the same non-overlapping and sorted MemRegion array.
692 void dealloc_archive_regions(MemRegion* range, size_t count);
693
694 protected:
695
696 // Shrink the garbage-first heap by at most the given size (in bytes!).
697 // (Rounds down to a HeapRegion boundary.)
698 virtual void shrink(size_t expand_bytes);
699 void shrink_helper(size_t expand_bytes);
700
701 #if TASKQUEUE_STATS
702 static void print_taskqueue_stats_hdr(outputStream* const st);
703 void print_taskqueue_stats() const;
704 void reset_taskqueue_stats();
705 #endif // TASKQUEUE_STATS
706
707 // Schedule the VM operation that will do an evacuation pause to
708 // satisfy an allocation request of word_size. *succeeded will
709 // return whether the VM operation was successful (it did do an
710 // evacuation pause) or not (another thread beat us to it or the GC
711 // locker was active). Given that we should not be holding the
712 // Heap_lock when we enter this method, we will pass the
713 // gc_count_before (i.e., total_collections()) as a parameter since
714 // it has to be read while holding the Heap_lock. Currently, both
715 // methods that call do_collection_pause() release the Heap_lock
716 // before the call, so it's easy to read gc_count_before just before.
717 HeapWord* do_collection_pause(size_t word_size,
718 uint gc_count_before,
719 bool* succeeded,
720 GCCause::Cause gc_cause);
721
722 void wait_for_root_region_scanning();
723
724 // The guts of the incremental collection pause, executed by the vm
725 // thread. It returns false if it is unable to do the collection due
726 // to the GC locker being active, true otherwise
727 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
728
729 // Actually do the work of evacuating the collection set.
730 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
731
732 void pre_evacuate_collection_set();
733 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
734
735 // Print the header for the per-thread termination statistics.
736 static void print_termination_stats_hdr();
737 // Print actual per-thread termination statistics.
738 void print_termination_stats(uint worker_id,
739 double elapsed_ms,
740 double strong_roots_ms,
741 double term_ms,
742 size_t term_attempts,
743 size_t alloc_buffer_waste,
744 size_t undo_waste) const;
745 // Update object copying statistics.
746 void record_obj_copy_mem_stats();
747
748 // The g1 remembered set of the heap.
749 G1RemSet* _g1_rem_set;
750
751 // A set of cards that cover the objects for which the Rsets should be updated
752 // concurrently after the collection.
753 DirtyCardQueueSet _dirty_card_queue_set;
754
755 // The closure used to refine a single card.
756 RefineCardTableEntryClosure* _refine_cte_cl;
757
758 // A DirtyCardQueueSet that is used to hold cards that contain
759 // references into the current collection set. This is used to
760 // update the remembered sets of the regions in the collection
761 // set in the event of an evacuation failure.
762 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
763
764 // After a collection pause, make the regions in the CS into free
765 // regions.
766 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
767
768 // Abandon the current collection set without recording policy
769 // statistics or updating free lists.
770 void abandon_collection_set(HeapRegion* cs_head);
771
772 // The concurrent marker (and the thread it runs in.)
773 ConcurrentMark* _cm;
774 ConcurrentMarkThread* _cmThread;
775
776 // The concurrent refiner.
777 ConcurrentG1Refine* _cg1r;
778
779 // The parallel task queues
780 RefToScanQueueSet *_task_queues;
781
782 // True iff a evacuation has failed in the current collection.
783 bool _evacuation_failed;
784
785 EvacuationFailedInfo* _evacuation_failed_info_array;
786
787 // Failed evacuations cause some logical from-space objects to have
788 // forwarding pointers to themselves. Reset them.
789 void remove_self_forwarding_pointers();
790
791 struct OopAndMarkOop {
792 private:
793 oop _o;
794 markOop _m;
795 public:
796 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) {
797 }
798
799 void set_mark() {
800 _o->set_mark(_m);
801 }
802 };
803
804 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack;
805 // Stores marks with the corresponding oop that we need to preserve during evacuation
806 // failure.
807 OopAndMarkOopStack* _preserved_objs;
808
809 // Preserve the mark of "obj", if necessary, in preparation for its mark
810 // word being overwritten with a self-forwarding-pointer.
811 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
812
813 #ifndef PRODUCT
814 // Support for forcing evacuation failures. Analogous to
815 // PromotionFailureALot for the other collectors.
816
817 // Records whether G1EvacuationFailureALot should be in effect
818 // for the current GC
819 bool _evacuation_failure_alot_for_current_gc;
820
821 // Used to record the GC number for interval checking when
822 // determining whether G1EvaucationFailureALot is in effect
823 // for the current GC.
824 size_t _evacuation_failure_alot_gc_number;
825
826 // Count of the number of evacuations between failures.
827 volatile size_t _evacuation_failure_alot_count;
828
829 // Set whether G1EvacuationFailureALot should be in effect
830 // for the current GC (based upon the type of GC and which
831 // command line flags are set);
832 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
833 bool during_initial_mark,
834 bool during_marking);
835
836 inline void set_evacuation_failure_alot_for_current_gc();
837
838 // Return true if it's time to cause an evacuation failure.
839 inline bool evacuation_should_fail();
840
841 // Reset the G1EvacuationFailureALot counters. Should be called at
842 // the end of an evacuation pause in which an evacuation failure occurred.
843 inline void reset_evacuation_should_fail();
844 #endif // !PRODUCT
845
846 // ("Weak") Reference processing support.
847 //
848 // G1 has 2 instances of the reference processor class. One
849 // (_ref_processor_cm) handles reference object discovery
850 // and subsequent processing during concurrent marking cycles.
851 //
852 // The other (_ref_processor_stw) handles reference object
853 // discovery and processing during full GCs and incremental
854 // evacuation pauses.
855 //
856 // During an incremental pause, reference discovery will be
857 // temporarily disabled for _ref_processor_cm and will be
858 // enabled for _ref_processor_stw. At the end of the evacuation
859 // pause references discovered by _ref_processor_stw will be
860 // processed and discovery will be disabled. The previous
861 // setting for reference object discovery for _ref_processor_cm
862 // will be re-instated.
863 //
864 // At the start of marking:
865 // * Discovery by the CM ref processor is verified to be inactive
866 // and it's discovered lists are empty.
867 // * Discovery by the CM ref processor is then enabled.
868 //
869 // At the end of marking:
870 // * Any references on the CM ref processor's discovered
871 // lists are processed (possibly MT).
872 //
873 // At the start of full GC we:
874 // * Disable discovery by the CM ref processor and
875 // empty CM ref processor's discovered lists
876 // (without processing any entries).
877 // * Verify that the STW ref processor is inactive and it's
878 // discovered lists are empty.
879 // * Temporarily set STW ref processor discovery as single threaded.
880 // * Temporarily clear the STW ref processor's _is_alive_non_header
881 // field.
882 // * Finally enable discovery by the STW ref processor.
883 //
884 // The STW ref processor is used to record any discovered
885 // references during the full GC.
886 //
887 // At the end of a full GC we:
888 // * Enqueue any reference objects discovered by the STW ref processor
889 // that have non-live referents. This has the side-effect of
890 // making the STW ref processor inactive by disabling discovery.
891 // * Verify that the CM ref processor is still inactive
892 // and no references have been placed on it's discovered
893 // lists (also checked as a precondition during initial marking).
894
895 // The (stw) reference processor...
896 ReferenceProcessor* _ref_processor_stw;
897
898 STWGCTimer* _gc_timer_stw;
899 ConcurrentGCTimer* _gc_timer_cm;
900
901 G1OldTracer* _gc_tracer_cm;
902 G1NewTracer* _gc_tracer_stw;
903
904 // During reference object discovery, the _is_alive_non_header
905 // closure (if non-null) is applied to the referent object to
906 // determine whether the referent is live. If so then the
907 // reference object does not need to be 'discovered' and can
908 // be treated as a regular oop. This has the benefit of reducing
909 // the number of 'discovered' reference objects that need to
910 // be processed.
911 //
912 // Instance of the is_alive closure for embedding into the
913 // STW reference processor as the _is_alive_non_header field.
914 // Supplying a value for the _is_alive_non_header field is
915 // optional but doing so prevents unnecessary additions to
916 // the discovered lists during reference discovery.
917 G1STWIsAliveClosure _is_alive_closure_stw;
918
919 // The (concurrent marking) reference processor...
920 ReferenceProcessor* _ref_processor_cm;
921
922 // Instance of the concurrent mark is_alive closure for embedding
923 // into the Concurrent Marking reference processor as the
924 // _is_alive_non_header field. Supplying a value for the
925 // _is_alive_non_header field is optional but doing so prevents
926 // unnecessary additions to the discovered lists during reference
927 // discovery.
928 G1CMIsAliveClosure _is_alive_closure_cm;
929
930 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
931 HeapRegion** _worker_cset_start_region;
932
933 // Time stamp to validate the regions recorded in the cache
934 // used by G1CollectedHeap::start_cset_region_for_worker().
935 // The heap region entry for a given worker is valid iff
936 // the associated time stamp value matches the current value
937 // of G1CollectedHeap::_gc_time_stamp.
938 uint* _worker_cset_start_region_time_stamp;
939
940 volatile bool _free_regions_coming;
941
942 public:
943
944 void set_refine_cte_cl_concurrency(bool concurrent);
945
946 RefToScanQueue *task_queue(uint i) const;
947
948 uint num_task_queues() const;
949
950 // A set of cards where updates happened during the GC
951 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
952
953 // A DirtyCardQueueSet that is used to hold cards that contain
954 // references into the current collection set. This is used to
955 // update the remembered sets of the regions in the collection
956 // set in the event of an evacuation failure.
957 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
958 { return _into_cset_dirty_card_queue_set; }
959
960 // Create a G1CollectedHeap with the specified policy.
961 // Must call the initialize method afterwards.
962 // May not return if something goes wrong.
963 G1CollectedHeap(G1CollectorPolicy* policy);
964
965 // Initialize the G1CollectedHeap to have the initial and
966 // maximum sizes and remembered and barrier sets
967 // specified by the policy object.
968 jint initialize();
969
970 virtual void stop();
971
972 // Return the (conservative) maximum heap alignment for any G1 heap
973 static size_t conservative_max_heap_alignment();
974
975 // Does operations required after initialization has been done.
976 void post_initialize();
977
978 // Initialize weak reference processing.
979 void ref_processing_init();
980
981 virtual Name kind() const {
982 return CollectedHeap::G1CollectedHeap;
983 }
984
985 const G1CollectorState* collector_state() const { return &_collector_state; }
986 G1CollectorState* collector_state() { return &_collector_state; }
987
988 // The current policy object for the collector.
989 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
990
991 virtual CollectorPolicy* collector_policy() const;
992
993 // Adaptive size policy. No such thing for g1.
994 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
995
996 // The rem set and barrier set.
997 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
998
999 unsigned get_gc_time_stamp() {
1000 return _gc_time_stamp;
1001 }
1002
1003 inline void reset_gc_time_stamp();
1004
1005 void check_gc_time_stamps() PRODUCT_RETURN;
1006
1007 inline void increment_gc_time_stamp();
1008
1009 // Reset the given region's GC timestamp. If it's starts humongous,
1010 // also reset the GC timestamp of its corresponding
1011 // continues humongous regions too.
1012 void reset_gc_time_stamps(HeapRegion* hr);
1013
1014 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1015 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1016
1017 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1018 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1019
1020 // The shared block offset table array.
1021 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1022
1023 // Reference Processing accessors
1024
1025 // The STW reference processor....
1026 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1027
1028 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1029
1030 // The Concurrent Marking reference processor...
1031 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1032
1033 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
1034 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
1035
1036 virtual size_t capacity() const;
1037 virtual size_t used() const;
1038 // This should be called when we're not holding the heap lock. The
1039 // result might be a bit inaccurate.
1040 size_t used_unlocked() const;
1041 size_t recalculate_used() const;
1042
1043 // These virtual functions do the actual allocation.
1044 // Some heaps may offer a contiguous region for shared non-blocking
1045 // allocation, via inlined code (by exporting the address of the top and
1046 // end fields defining the extent of the contiguous allocation region.)
1047 // But G1CollectedHeap doesn't yet support this.
1048
1049 virtual bool is_maximal_no_gc() const {
1050 return _hrm.available() == 0;
1051 }
1052
1053 // The current number of regions in the heap.
1054 uint num_regions() const { return _hrm.length(); }
1055
1056 // The max number of regions in the heap.
1057 uint max_regions() const { return _hrm.max_length(); }
1058
1059 // The number of regions that are completely free.
1060 uint num_free_regions() const { return _hrm.num_free_regions(); }
1061
1062 MemoryUsage get_auxiliary_data_memory_usage() const {
1063 return _hrm.get_auxiliary_data_memory_usage();
1064 }
1065
1066 // The number of regions that are not completely free.
1067 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1068
1069 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1070 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1071 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1072 void verify_dirty_young_regions() PRODUCT_RETURN;
1073
1074 #ifndef PRODUCT
1075 // Make sure that the given bitmap has no marked objects in the
1076 // range [from,limit). If it does, print an error message and return
1077 // false. Otherwise, just return true. bitmap_name should be "prev"
1078 // or "next".
1079 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
1080 HeapWord* from, HeapWord* limit);
1081
1082 // Verify that the prev / next bitmap range [tams,end) for the given
1083 // region has no marks. Return true if all is well, false if errors
1084 // are detected.
1085 bool verify_bitmaps(const char* caller, HeapRegion* hr);
1086 #endif // PRODUCT
1087
1088 // If G1VerifyBitmaps is set, verify that the marking bitmaps for
1089 // the given region do not have any spurious marks. If errors are
1090 // detected, print appropriate error messages and crash.
1091 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN;
1092
1093 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not
1094 // have any spurious marks. If errors are detected, print
1095 // appropriate error messages and crash.
1096 void check_bitmaps(const char* caller) PRODUCT_RETURN;
1097
1098 // Do sanity check on the contents of the in-cset fast test table.
1099 bool check_cset_fast_test() PRODUCT_RETURN_( return true; );
1100
1101 // verify_region_sets() performs verification over the region
1102 // lists. It will be compiled in the product code to be used when
1103 // necessary (i.e., during heap verification).
1104 void verify_region_sets();
1105
1106 // verify_region_sets_optional() is planted in the code for
1107 // list verification in non-product builds (and it can be enabled in
1108 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1).
1109 #if HEAP_REGION_SET_FORCE_VERIFY
1110 void verify_region_sets_optional() {
1111 verify_region_sets();
1112 }
1113 #else // HEAP_REGION_SET_FORCE_VERIFY
1114 void verify_region_sets_optional() { }
1115 #endif // HEAP_REGION_SET_FORCE_VERIFY
1116
1117 #ifdef ASSERT
1118 bool is_on_master_free_list(HeapRegion* hr) {
1119 return _hrm.is_free(hr);
1120 }
1121 #endif // ASSERT
1122
1123 // Wrapper for the region list operations that can be called from
1124 // methods outside this class.
1125
1126 void secondary_free_list_add(FreeRegionList* list) {
1127 _secondary_free_list.add_ordered(list);
1128 }
1129
1130 void append_secondary_free_list() {
1131 _hrm.insert_list_into_free_list(&_secondary_free_list);
1132 }
1133
1134 void append_secondary_free_list_if_not_empty_with_lock() {
1135 // If the secondary free list looks empty there's no reason to
1136 // take the lock and then try to append it.
1137 if (!_secondary_free_list.is_empty()) {
1138 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1139 append_secondary_free_list();
1140 }
1141 }
1142
1143 inline void old_set_add(HeapRegion* hr);
1144 inline void old_set_remove(HeapRegion* hr);
1145
1146 size_t non_young_capacity_bytes() {
1147 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1148 }
1149
1150 void set_free_regions_coming();
1151 void reset_free_regions_coming();
1152 bool free_regions_coming() { return _free_regions_coming; }
1153 void wait_while_free_regions_coming();
1154
1155 // Determine whether the given region is one that we are using as an
1156 // old GC alloc region.
1157 bool is_old_gc_alloc_region(HeapRegion* hr);
1158
1159 // Perform a collection of the heap; intended for use in implementing
1160 // "System.gc". This probably implies as full a collection as the
1161 // "CollectedHeap" supports.
1162 virtual void collect(GCCause::Cause cause);
1163
1164 // The same as above but assume that the caller holds the Heap_lock.
1165 void collect_locked(GCCause::Cause cause);
1166
1167 virtual bool copy_allocation_context_stats(const jint* contexts,
1168 jlong* totals,
1169 jbyte* accuracy,
1170 jint len);
1171
1172 // True iff an evacuation has failed in the most-recent collection.
1173 bool evacuation_failed() { return _evacuation_failed; }
1174
1175 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed);
1176 void prepend_to_freelist(FreeRegionList* list);
1177 void decrement_summary_bytes(size_t bytes);
1178
1179 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1180 virtual bool is_in(const void* p) const;
1181 #ifdef ASSERT
1182 // Returns whether p is in one of the available areas of the heap. Slow but
1183 // extensive version.
1184 bool is_in_exact(const void* p) const;
1185 #endif
1186
1187 // Return "TRUE" iff the given object address is within the collection
1188 // set. Slow implementation.
1189 bool obj_in_cs(oop obj);
1190
1191 inline bool is_in_cset(const HeapRegion *hr);
1192 inline bool is_in_cset(oop obj);
1193
1194 inline bool is_in_cset_or_humongous(const oop obj);
1195
1196 private:
1197 // This array is used for a quick test on whether a reference points into
1198 // the collection set or not. Each of the array's elements denotes whether the
1199 // corresponding region is in the collection set or not.
1200 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1201
1202 public:
1203
1204 inline InCSetState in_cset_state(const oop obj);
1205
1206 // Return "TRUE" iff the given object address is in the reserved
1207 // region of g1.
1208 bool is_in_g1_reserved(const void* p) const {
1209 return _hrm.reserved().contains(p);
1210 }
1211
1212 // Returns a MemRegion that corresponds to the space that has been
1213 // reserved for the heap
1214 MemRegion g1_reserved() const {
1215 return _hrm.reserved();
1216 }
1217
1218 virtual bool is_in_closed_subset(const void* p) const;
1219
1220 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1221 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1222 }
1223
1224 // This resets the card table to all zeros. It is used after
1225 // a collection pause which used the card table to claim cards.
1226 void cleanUpCardTable();
1227
1228 // Iteration functions.
1229
1230 // Iterate over all objects, calling "cl.do_object" on each.
1231 virtual void object_iterate(ObjectClosure* cl);
1232
1233 virtual void safe_object_iterate(ObjectClosure* cl) {
1234 object_iterate(cl);
1235 }
1236
1237 // Iterate over heap regions, in address order, terminating the
1238 // iteration early if the "doHeapRegion" method returns "true".
1239 void heap_region_iterate(HeapRegionClosure* blk) const;
1240
1241 // Return the region with the given index. It assumes the index is valid.
1242 inline HeapRegion* region_at(uint index) const;
1243
1244 // Calculate the region index of the given address. Given address must be
1245 // within the heap.
1246 inline uint addr_to_region(HeapWord* addr) const;
1247
1248 inline HeapWord* bottom_addr_for_region(uint index) const;
1249
1250 // Iterate over the heap regions in parallel. Assumes that this will be called
1251 // in parallel by ParallelGCThreads worker threads with distinct worker ids
1252 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
1253 // to each of the regions, by attempting to claim the region using the
1254 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1255 // region. The concurrent argument should be set to true if iteration is
1256 // performed concurrently, during which no assumptions are made for consistent
1257 // attributes of the heap regions (as they might be modified while iterating).
1258 void heap_region_par_iterate(HeapRegionClosure* cl,
1259 uint worker_id,
1260 HeapRegionClaimer* hrclaimer,
1261 bool concurrent = false) const;
1262
1263 // Clear the cached cset start regions and (more importantly)
1264 // the time stamps. Called when we reset the GC time stamp.
1265 void clear_cset_start_regions();
1266
1267 // Given the id of a worker, obtain or calculate a suitable
1268 // starting region for iterating over the current collection set.
1269 HeapRegion* start_cset_region_for_worker(uint worker_i);
1270
1271 // Iterate over the regions (if any) in the current collection set.
1272 void collection_set_iterate(HeapRegionClosure* blk);
1273
1274 // As above but starting from region r
1275 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1276
1277 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1278
1279 // Returns the HeapRegion that contains addr. addr must not be NULL.
1280 template <class T>
1281 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1282
1283 // Returns the HeapRegion that contains addr. addr must not be NULL.
1284 // If addr is within a humongous continues region, it returns its humongous start region.
1285 template <class T>
1286 inline HeapRegion* heap_region_containing(const T addr) const;
1287
1288 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1289 // each address in the (reserved) heap is a member of exactly
1290 // one block. The defining characteristic of a block is that it is
1291 // possible to find its size, and thus to progress forward to the next
1292 // block. (Blocks may be of different sizes.) Thus, blocks may
1293 // represent Java objects, or they might be free blocks in a
1294 // free-list-based heap (or subheap), as long as the two kinds are
1295 // distinguishable and the size of each is determinable.
1296
1297 // Returns the address of the start of the "block" that contains the
1298 // address "addr". We say "blocks" instead of "object" since some heaps
1299 // may not pack objects densely; a chunk may either be an object or a
1300 // non-object.
1301 virtual HeapWord* block_start(const void* addr) const;
1302
1303 // Requires "addr" to be the start of a chunk, and returns its size.
1304 // "addr + size" is required to be the start of a new chunk, or the end
1305 // of the active area of the heap.
1306 virtual size_t block_size(const HeapWord* addr) const;
1307
1308 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1309 // the block is an object.
1310 virtual bool block_is_obj(const HeapWord* addr) const;
1311
1312 // Section on thread-local allocation buffers (TLABs)
1313 // See CollectedHeap for semantics.
1314
1315 bool supports_tlab_allocation() const;
1316 size_t tlab_capacity(Thread* ignored) const;
1317 size_t tlab_used(Thread* ignored) const;
1318 size_t max_tlab_size() const;
1319 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1320
1321 // Can a compiler initialize a new object without store barriers?
1322 // This permission only extends from the creation of a new object
1323 // via a TLAB up to the first subsequent safepoint. If such permission
1324 // is granted for this heap type, the compiler promises to call
1325 // defer_store_barrier() below on any slow path allocation of
1326 // a new object for which such initializing store barriers will
1327 // have been elided. G1, like CMS, allows this, but should be
1328 // ready to provide a compensating write barrier as necessary
1329 // if that storage came out of a non-young region. The efficiency
1330 // of this implementation depends crucially on being able to
1331 // answer very efficiently in constant time whether a piece of
1332 // storage in the heap comes from a young region or not.
1333 // See ReduceInitialCardMarks.
1334 virtual bool can_elide_tlab_store_barriers() const {
1335 return true;
1336 }
1337
1338 virtual bool card_mark_must_follow_store() const {
1339 return true;
1340 }
1341
1342 inline bool is_in_young(const oop obj);
1343
1344 virtual bool is_scavengable(const void* addr);
1345
1346 // We don't need barriers for initializing stores to objects
1347 // in the young gen: for the SATB pre-barrier, there is no
1348 // pre-value that needs to be remembered; for the remembered-set
1349 // update logging post-barrier, we don't maintain remembered set
1350 // information for young gen objects.
1351 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1352
1353 // Returns "true" iff the given word_size is "very large".
1354 static bool is_humongous(size_t word_size) {
1355 // Note this has to be strictly greater-than as the TLABs
1356 // are capped at the humongous threshold and we want to
1357 // ensure that we don't try to allocate a TLAB as
1358 // humongous and that we don't allocate a humongous
1359 // object in a TLAB.
1360 return word_size > _humongous_object_threshold_in_words;
1361 }
1362
1363 // Returns the humongous threshold for a specific region size
1364 static size_t humongous_threshold_for(size_t region_size) {
1365 return (region_size / 2);
1366 }
1367
1368 // Update mod union table with the set of dirty cards.
1369 void updateModUnion();
1370
1371 // Set the mod union bits corresponding to the given memRegion. Note
1372 // that this is always a safe operation, since it doesn't clear any
1373 // bits.
1374 void markModUnionRange(MemRegion mr);
1375
1376 // Print the maximum heap capacity.
1377 virtual size_t max_capacity() const;
1378
1379 virtual jlong millis_since_last_gc();
1380
1381
1382 // Convenience function to be used in situations where the heap type can be
1383 // asserted to be this type.
1384 static G1CollectedHeap* heap();
1385
1386 void set_region_short_lived_locked(HeapRegion* hr);
1387 // add appropriate methods for any other surv rate groups
1388
1389 YoungList* young_list() const { return _young_list; }
1390
1391 // debugging
1392 bool check_young_list_well_formed() {
1393 return _young_list->check_list_well_formed();
1394 }
1395
1396 bool check_young_list_empty(bool check_heap,
1397 bool check_sample = true);
1398
1399 // *** Stuff related to concurrent marking. It's not clear to me that so
1400 // many of these need to be public.
1401
1402 // The functions below are helper functions that a subclass of
1403 // "CollectedHeap" can use in the implementation of its virtual
1404 // functions.
1405 // This performs a concurrent marking of the live objects in a
1406 // bitmap off to the side.
1407 void doConcurrentMark();
1408
1409 bool isMarkedPrev(oop obj) const;
1410 bool isMarkedNext(oop obj) const;
1411
1412 // Determine if an object is dead, given the object and also
1413 // the region to which the object belongs. An object is dead
1414 // iff a) it was not allocated since the last mark, b) it
1415 // is not marked, and c) it is not in an archive region.
1416 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1417 return
1418 !hr->obj_allocated_since_prev_marking(obj) &&
1419 !isMarkedPrev(obj) &&
1420 !hr->is_archive();
1421 }
1422
1423 // This function returns true when an object has been
1424 // around since the previous marking and hasn't yet
1425 // been marked during this marking, and is not in an archive region.
1426 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1427 return
1428 !hr->obj_allocated_since_next_marking(obj) &&
1429 !isMarkedNext(obj) &&
1430 !hr->is_archive();
1431 }
1432
1433 // Determine if an object is dead, given only the object itself.
1434 // This will find the region to which the object belongs and
1435 // then call the region version of the same function.
1436
1437 // Added if it is NULL it isn't dead.
1438
1439 inline bool is_obj_dead(const oop obj) const;
1440
1441 inline bool is_obj_ill(const oop obj) const;
1442
1443 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo);
1444 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo);
1445 bool is_marked(oop obj, VerifyOption vo);
1446 const char* top_at_mark_start_str(VerifyOption vo);
1447
1448 ConcurrentMark* concurrent_mark() const { return _cm; }
1449
1450 // Refinement
1451
1452 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1453
1454 // The dirty cards region list is used to record a subset of regions
1455 // whose cards need clearing. The list if populated during the
1456 // remembered set scanning and drained during the card table
1457 // cleanup. Although the methods are reentrant, population/draining
1458 // phases must not overlap. For synchronization purposes the last
1459 // element on the list points to itself.
1460 HeapRegion* _dirty_cards_region_list;
1461 void push_dirty_cards_region(HeapRegion* hr);
1462 HeapRegion* pop_dirty_cards_region();
1463
1464 // Optimized nmethod scanning support routines
1465
1466 // Register the given nmethod with the G1 heap.
1467 virtual void register_nmethod(nmethod* nm);
1468
1469 // Unregister the given nmethod from the G1 heap.
1470 virtual void unregister_nmethod(nmethod* nm);
1471
1472 // Free up superfluous code root memory.
1473 void purge_code_root_memory();
1474
1475 // Rebuild the strong code root lists for each region
1476 // after a full GC.
1477 void rebuild_strong_code_roots();
1478
1479 // Delete entries for dead interned string and clean up unreferenced symbols
1480 // in symbol table, possibly in parallel.
1481 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true);
1482
1483 // Parallel phase of unloading/cleaning after G1 concurrent mark.
1484 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred);
1485
1486 // Redirty logged cards in the refinement queue.
1487 void redirty_logged_cards();
1488 // Verification
1489
1490 // Perform any cleanup actions necessary before allowing a verification.
1491 virtual void prepare_for_verify();
1492
1493 // Perform verification.
1494
1495 // vo == UsePrevMarking -> use "prev" marking information,
1496 // vo == UseNextMarking -> use "next" marking information
1497 // vo == UseMarkWord -> use the mark word in the object header
1498 //
1499 // NOTE: Only the "prev" marking information is guaranteed to be
1500 // consistent most of the time, so most calls to this should use
1501 // vo == UsePrevMarking.
1502 // Currently, there is only one case where this is called with
1503 // vo == UseNextMarking, which is to verify the "next" marking
1504 // information at the end of remark.
1505 // Currently there is only one place where this is called with
1506 // vo == UseMarkWord, which is to verify the marking during a
1507 // full GC.
1508 void verify(VerifyOption vo);
1509
1510 // The methods below are here for convenience and dispatch the
1511 // appropriate method depending on value of the given VerifyOption
1512 // parameter. The values for that parameter, and their meanings,
1513 // are the same as those above.
1514
1515 bool is_obj_dead_cond(const oop obj,
1516 const HeapRegion* hr,
1517 const VerifyOption vo) const;
1518
1519 bool is_obj_dead_cond(const oop obj,
1520 const VerifyOption vo) const;
1521
1522 G1HeapSummary create_g1_heap_summary();
1523 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1524
1525 // Printing
1526
1527 virtual void print_on(outputStream* st) const;
1528 virtual void print_extended_on(outputStream* st) const;
1529 virtual void print_on_error(outputStream* st) const;
1530
1531 virtual void print_gc_threads_on(outputStream* st) const;
1532 virtual void gc_threads_do(ThreadClosure* tc) const;
1533
1534 // Override
1535 void print_tracing_info() const;
1536
1537 // The following two methods are helpful for debugging RSet issues.
1538 void print_cset_rsets() PRODUCT_RETURN;
1539 void print_all_rsets() PRODUCT_RETURN;
1540
1541 public:
1542 size_t pending_card_num();
1543
1544 protected:
1545 size_t _max_heap_capacity;
1546 };
1547
1548 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP