1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc_implementation/g1/concurrentMark.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
40
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
45
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
64
65 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
67
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
76
77 class YoungList : public CHeapObj {
78 private:
79 G1CollectedHeap* _g1h;
80
81 HeapRegion* _head;
82
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
85
86 HeapRegion* _curr;
87
88 size_t _length;
89 size_t _survivor_length;
90
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
93
94 void empty_list(HeapRegion* list);
95
96 public:
97 YoungList(G1CollectedHeap* g1h);
98
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
101
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 size_t length() { return _length; }
105 size_t survivor_length() { return _survivor_length; }
106
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return survivor_length() * HeapRegion::GrainBytes;
118 }
119
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
123
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
132
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
138
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
142
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
148
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
156 };
157
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // _is_alive_non_header closure in the STW reference
161 // processor. It is also extensively used during refence
162 // processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
168 bool do_object_b(oop p);
169 };
170
171 class RefineCardTableEntryClosure;
172
173 class G1CollectedHeap : public SharedHeap {
174 friend class VM_G1CollectForAllocation;
175 friend class VM_GenCollectForPermanentAllocation;
176 friend class VM_G1CollectFull;
177 friend class VM_G1IncCollectionPause;
178 friend class VMStructs;
179 friend class MutatorAllocRegion;
180
181 // Closures used in implementation.
182 friend class G1ParCopyHelper;
183 friend class G1IsAliveClosure;
184 friend class G1EvacuateFollowersClosure;
185 friend class G1ParScanThreadState;
186 friend class G1ParScanClosureSuper;
187 friend class G1ParEvacuateFollowersClosure;
188 friend class G1ParTask;
189 friend class G1FreeGarbageRegionClosure;
190 friend class RefineCardTableEntryClosure;
191 friend class G1PrepareCompactClosure;
192 friend class RegionSorter;
193 friend class RegionResetter;
194 friend class CountRCClosure;
195 friend class EvacPopObjClosure;
196 friend class G1ParCleanupCTTask;
197
198 // Other related classes.
199 friend class G1MarkSweep;
200
201 private:
202 // The one and only G1CollectedHeap, so static functions can find it.
203 static G1CollectedHeap* _g1h;
204
205 static size_t _humongous_object_threshold_in_words;
206
207 // Storage for the G1 heap (excludes the permanent generation).
208 VirtualSpace _g1_storage;
209 MemRegion _g1_reserved;
210
211 // The part of _g1_storage that is currently committed.
212 MemRegion _g1_committed;
213
214 // The master free list. It will satisfy all new region allocations.
215 MasterFreeRegionList _free_list;
216
217 // The secondary free list which contains regions that have been
218 // freed up during the cleanup process. This will be appended to the
219 // master free list when appropriate.
220 SecondaryFreeRegionList _secondary_free_list;
221
222 // It keeps track of the humongous regions.
223 MasterHumongousRegionSet _humongous_set;
224
225 // The number of regions we could create by expansion.
226 size_t _expansion_regions;
227
228 // The block offset table for the G1 heap.
229 G1BlockOffsetSharedArray* _bot_shared;
230
231 // Move all of the regions off the free lists, then rebuild those free
232 // lists, before and after full GC.
233 void tear_down_region_lists();
234 void rebuild_region_lists();
235
236 // The sequence of all heap regions in the heap.
237 HeapRegionSeq _hrs;
238
239 // Alloc region used to satisfy mutator allocation requests.
240 MutatorAllocRegion _mutator_alloc_region;
241
242 // It resets the mutator alloc region before new allocations can take place.
243 void init_mutator_alloc_region();
244
245 // It releases the mutator alloc region.
246 void release_mutator_alloc_region();
247
248 void abandon_gc_alloc_regions();
249
250 // The to-space memory regions into which objects are being copied during
251 // a GC.
252 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
253 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
254 // These are the regions, one per GCAllocPurpose, that are half-full
255 // at the end of a collection and that we want to reuse during the
256 // next collection.
257 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
258 // This specifies whether we will keep the last half-full region at
259 // the end of a collection so that it can be reused during the next
260 // collection (this is specified per GCAllocPurpose)
261 bool _retain_gc_alloc_region[GCAllocPurposeCount];
262
263 // A list of the regions that have been set to be alloc regions in the
264 // current collection.
265 HeapRegion* _gc_alloc_region_list;
266
267 // Helper for monitoring and management support.
268 G1MonitoringSupport* _g1mm;
269
270 // Determines PLAB size for a particular allocation purpose.
271 static size_t desired_plab_sz(GCAllocPurpose purpose);
272
273 // When called by par thread, requires the FreeList_lock to be held.
274 void push_gc_alloc_region(HeapRegion* hr);
275
276 // This should only be called single-threaded. Undeclares all GC alloc
277 // regions.
278 void forget_alloc_region_list();
279
280 // Should be used to set an alloc region, because there's other
281 // associated bookkeeping.
282 void set_gc_alloc_region(int purpose, HeapRegion* r);
283
284 // Check well-formedness of alloc region list.
285 bool check_gc_alloc_regions();
286
287 // Outside of GC pauses, the number of bytes used in all regions other
288 // than the current allocation region.
289 size_t _summary_bytes_used;
290
291 // This is used for a quick test on whether a reference points into
292 // the collection set or not. Basically, we have an array, with one
293 // byte per region, and that byte denotes whether the corresponding
294 // region is in the collection set or not. The entry corresponding
295 // the bottom of the heap, i.e., region 0, is pointed to by
296 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
297 // biased so that it actually points to address 0 of the address
298 // space, to make the test as fast as possible (we can simply shift
299 // the address to address into it, instead of having to subtract the
300 // bottom of the heap from the address before shifting it; basically
301 // it works in the same way the card table works).
302 bool* _in_cset_fast_test;
303
304 // The allocated array used for the fast test on whether a reference
305 // points into the collection set or not. This field is also used to
306 // free the array.
307 bool* _in_cset_fast_test_base;
308
309 // The length of the _in_cset_fast_test_base array.
310 size_t _in_cset_fast_test_length;
311
312 volatile unsigned _gc_time_stamp;
313
314 size_t* _surviving_young_words;
315
316 G1HRPrinter _hr_printer;
317
318 void setup_surviving_young_words();
319 void update_surviving_young_words(size_t* surv_young_words);
320 void cleanup_surviving_young_words();
321
322 // It decides whether an explicit GC should start a concurrent cycle
323 // instead of doing a STW GC. Currently, a concurrent cycle is
324 // explicitly started if:
325 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
326 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
327 bool should_do_concurrent_full_gc(GCCause::Cause cause);
328
329 // Keeps track of how many "full collections" (i.e., Full GCs or
330 // concurrent cycles) we have completed. The number of them we have
331 // started is maintained in _total_full_collections in CollectedHeap.
332 volatile unsigned int _full_collections_completed;
333
334 // This is a non-product method that is helpful for testing. It is
335 // called at the end of a GC and artificially expands the heap by
336 // allocating a number of dead regions. This way we can induce very
337 // frequent marking cycles and stress the cleanup / concurrent
338 // cleanup code more (as all the regions that will be allocated by
339 // this method will be found dead by the marking cycle).
340 void allocate_dummy_regions() PRODUCT_RETURN;
341
342 // These are macros so that, if the assert fires, we get the correct
343 // line number, file, etc.
344
345 #define heap_locking_asserts_err_msg(_extra_message_) \
346 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
347 (_extra_message_), \
348 BOOL_TO_STR(Heap_lock->owned_by_self()), \
349 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
350 BOOL_TO_STR(Thread::current()->is_VM_thread()))
351
352 #define assert_heap_locked() \
353 do { \
354 assert(Heap_lock->owned_by_self(), \
355 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
356 } while (0)
357
358 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
359 do { \
360 assert(Heap_lock->owned_by_self() || \
361 (SafepointSynchronize::is_at_safepoint() && \
362 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
363 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
364 "should be at a safepoint")); \
365 } while (0)
366
367 #define assert_heap_locked_and_not_at_safepoint() \
368 do { \
369 assert(Heap_lock->owned_by_self() && \
370 !SafepointSynchronize::is_at_safepoint(), \
371 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
372 "should not be at a safepoint")); \
373 } while (0)
374
375 #define assert_heap_not_locked() \
376 do { \
377 assert(!Heap_lock->owned_by_self(), \
378 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
379 } while (0)
380
381 #define assert_heap_not_locked_and_not_at_safepoint() \
382 do { \
383 assert(!Heap_lock->owned_by_self() && \
384 !SafepointSynchronize::is_at_safepoint(), \
385 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
386 "should not be at a safepoint")); \
387 } while (0)
388
389 #define assert_at_safepoint(_should_be_vm_thread_) \
390 do { \
391 assert(SafepointSynchronize::is_at_safepoint() && \
392 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
393 heap_locking_asserts_err_msg("should be at a safepoint")); \
394 } while (0)
395
396 #define assert_not_at_safepoint() \
397 do { \
398 assert(!SafepointSynchronize::is_at_safepoint(), \
399 heap_locking_asserts_err_msg("should not be at a safepoint")); \
400 } while (0)
401
402 protected:
403
404 // Returns "true" iff none of the gc alloc regions have any allocations
405 // since the last call to "save_marks".
406 bool all_alloc_regions_no_allocs_since_save_marks();
407 // Perform finalization stuff on all allocation regions.
408 void retire_all_alloc_regions();
409
410 // The young region list.
411 YoungList* _young_list;
412
413 // The current policy object for the collector.
414 G1CollectorPolicy* _g1_policy;
415
416 // This is the second level of trying to allocate a new region. If
417 // new_region() didn't find a region on the free_list, this call will
418 // check whether there's anything available on the
419 // secondary_free_list and/or wait for more regions to appear on
420 // that list, if _free_regions_coming is set.
421 HeapRegion* new_region_try_secondary_free_list();
422
423 // Try to allocate a single non-humongous HeapRegion sufficient for
424 // an allocation of the given word_size. If do_expand is true,
425 // attempt to expand the heap if necessary to satisfy the allocation
426 // request.
427 HeapRegion* new_region(size_t word_size, bool do_expand);
428
429 // Try to allocate a new region to be used for allocation by
430 // a GC thread. It will try to expand the heap if no region is
431 // available.
432 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
433
434 // Attempt to satisfy a humongous allocation request of the given
435 // size by finding a contiguous set of free regions of num_regions
436 // length and remove them from the master free list. Return the
437 // index of the first region or G1_NULL_HRS_INDEX if the search
438 // was unsuccessful.
439 size_t humongous_obj_allocate_find_first(size_t num_regions,
440 size_t word_size);
441
442 // Initialize a contiguous set of free regions of length num_regions
443 // and starting at index first so that they appear as a single
444 // humongous region.
445 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
446 size_t num_regions,
447 size_t word_size);
448
449 // Attempt to allocate a humongous object of the given size. Return
450 // NULL if unsuccessful.
451 HeapWord* humongous_obj_allocate(size_t word_size);
452
453 // The following two methods, allocate_new_tlab() and
454 // mem_allocate(), are the two main entry points from the runtime
455 // into the G1's allocation routines. They have the following
456 // assumptions:
457 //
458 // * They should both be called outside safepoints.
459 //
460 // * They should both be called without holding the Heap_lock.
461 //
462 // * All allocation requests for new TLABs should go to
463 // allocate_new_tlab().
464 //
465 // * All non-TLAB allocation requests should go to mem_allocate().
466 //
467 // * If either call cannot satisfy the allocation request using the
468 // current allocating region, they will try to get a new one. If
469 // this fails, they will attempt to do an evacuation pause and
470 // retry the allocation.
471 //
472 // * If all allocation attempts fail, even after trying to schedule
473 // an evacuation pause, allocate_new_tlab() will return NULL,
474 // whereas mem_allocate() will attempt a heap expansion and/or
475 // schedule a Full GC.
476 //
477 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
478 // should never be called with word_size being humongous. All
479 // humongous allocation requests should go to mem_allocate() which
480 // will satisfy them with a special path.
481
482 virtual HeapWord* allocate_new_tlab(size_t word_size);
483
484 virtual HeapWord* mem_allocate(size_t word_size,
485 bool* gc_overhead_limit_was_exceeded);
486
487 // The following three methods take a gc_count_before_ret
488 // parameter which is used to return the GC count if the method
489 // returns NULL. Given that we are required to read the GC count
490 // while holding the Heap_lock, and these paths will take the
491 // Heap_lock at some point, it's easier to get them to read the GC
492 // count while holding the Heap_lock before they return NULL instead
493 // of the caller (namely: mem_allocate()) having to also take the
494 // Heap_lock just to read the GC count.
495
496 // First-level mutator allocation attempt: try to allocate out of
497 // the mutator alloc region without taking the Heap_lock. This
498 // should only be used for non-humongous allocations.
499 inline HeapWord* attempt_allocation(size_t word_size,
500 unsigned int* gc_count_before_ret);
501
502 // Second-level mutator allocation attempt: take the Heap_lock and
503 // retry the allocation attempt, potentially scheduling a GC
504 // pause. This should only be used for non-humongous allocations.
505 HeapWord* attempt_allocation_slow(size_t word_size,
506 unsigned int* gc_count_before_ret);
507
508 // Takes the Heap_lock and attempts a humongous allocation. It can
509 // potentially schedule a GC pause.
510 HeapWord* attempt_allocation_humongous(size_t word_size,
511 unsigned int* gc_count_before_ret);
512
513 // Allocation attempt that should be called during safepoints (e.g.,
514 // at the end of a successful GC). expect_null_mutator_alloc_region
515 // specifies whether the mutator alloc region is expected to be NULL
516 // or not.
517 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
518 bool expect_null_mutator_alloc_region);
519
520 // It dirties the cards that cover the block so that so that the post
521 // write barrier never queues anything when updating objects on this
522 // block. It is assumed (and in fact we assert) that the block
523 // belongs to a young region.
524 inline void dirty_young_block(HeapWord* start, size_t word_size);
525
526 // Allocate blocks during garbage collection. Will ensure an
527 // allocation region, either by picking one or expanding the
528 // heap, and then allocate a block of the given size. The block
529 // may not be a humongous - it must fit into a single heap region.
530 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
531
532 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
533 HeapRegion* alloc_region,
534 bool par,
535 size_t word_size);
536
537 // Ensure that no further allocations can happen in "r", bearing in mind
538 // that parallel threads might be attempting allocations.
539 void par_allocate_remaining_space(HeapRegion* r);
540
541 // Retires an allocation region when it is full or at the end of a
542 // GC pause.
543 void retire_alloc_region(HeapRegion* alloc_region, bool par);
544
545 // These two methods are the "callbacks" from the G1AllocRegion class.
546
547 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
548 void retire_mutator_alloc_region(HeapRegion* alloc_region,
549 size_t allocated_bytes);
550
551 // - if explicit_gc is true, the GC is for a System.gc() or a heap
552 // inspection request and should collect the entire heap
553 // - if clear_all_soft_refs is true, all soft references should be
554 // cleared during the GC
555 // - if explicit_gc is false, word_size describes the allocation that
556 // the GC should attempt (at least) to satisfy
557 // - it returns false if it is unable to do the collection due to the
558 // GC locker being active, true otherwise
559 bool do_collection(bool explicit_gc,
560 bool clear_all_soft_refs,
561 size_t word_size);
562
563 // Callback from VM_G1CollectFull operation.
564 // Perform a full collection.
565 void do_full_collection(bool clear_all_soft_refs);
566
567 // Resize the heap if necessary after a full collection. If this is
568 // after a collect-for allocation, "word_size" is the allocation size,
569 // and will be considered part of the used portion of the heap.
570 void resize_if_necessary_after_full_collection(size_t word_size);
571
572 // Callback from VM_G1CollectForAllocation operation.
573 // This function does everything necessary/possible to satisfy a
574 // failed allocation request (including collection, expansion, etc.)
575 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
576
577 // Attempting to expand the heap sufficiently
578 // to support an allocation of the given "word_size". If
579 // successful, perform the allocation and return the address of the
580 // allocated block, or else "NULL".
581 HeapWord* expand_and_allocate(size_t word_size);
582
583 // Process any reference objects discovered during
584 // an incremental evacuation pause.
585 void process_discovered_references();
586
587 // Enqueue any remaining discovered references
588 // after processing.
589 void enqueue_discovered_references();
590
591 public:
592
593 G1MonitoringSupport* g1mm() { return _g1mm; }
594
595 // Expand the garbage-first heap by at least the given size (in bytes!).
596 // Returns true if the heap was expanded by the requested amount;
597 // false otherwise.
598 // (Rounds up to a HeapRegion boundary.)
599 bool expand(size_t expand_bytes);
600
601 // Do anything common to GC's.
602 virtual void gc_prologue(bool full);
603 virtual void gc_epilogue(bool full);
604
605 // We register a region with the fast "in collection set" test. We
606 // simply set to true the array slot corresponding to this region.
607 void register_region_with_in_cset_fast_test(HeapRegion* r) {
608 assert(_in_cset_fast_test_base != NULL, "sanity");
609 assert(r->in_collection_set(), "invariant");
610 size_t index = r->hrs_index();
611 assert(index < _in_cset_fast_test_length, "invariant");
612 assert(!_in_cset_fast_test_base[index], "invariant");
613 _in_cset_fast_test_base[index] = true;
614 }
615
616 // This is a fast test on whether a reference points into the
617 // collection set or not. It does not assume that the reference
618 // points into the heap; if it doesn't, it will return false.
619 bool in_cset_fast_test(oop obj) {
620 assert(_in_cset_fast_test != NULL, "sanity");
621 if (_g1_committed.contains((HeapWord*) obj)) {
622 // no need to subtract the bottom of the heap from obj,
623 // _in_cset_fast_test is biased
624 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
625 bool ret = _in_cset_fast_test[index];
626 // let's make sure the result is consistent with what the slower
627 // test returns
628 assert( ret || !obj_in_cs(obj), "sanity");
629 assert(!ret || obj_in_cs(obj), "sanity");
630 return ret;
631 } else {
632 return false;
633 }
634 }
635
636 void clear_cset_fast_test() {
637 assert(_in_cset_fast_test_base != NULL, "sanity");
638 memset(_in_cset_fast_test_base, false,
639 _in_cset_fast_test_length * sizeof(bool));
640 }
641
642 // This is called at the end of either a concurrent cycle or a Full
643 // GC to update the number of full collections completed. Those two
644 // can happen in a nested fashion, i.e., we start a concurrent
645 // cycle, a Full GC happens half-way through it which ends first,
646 // and then the cycle notices that a Full GC happened and ends
647 // too. The concurrent parameter is a boolean to help us do a bit
648 // tighter consistency checking in the method. If concurrent is
649 // false, the caller is the inner caller in the nesting (i.e., the
650 // Full GC). If concurrent is true, the caller is the outer caller
651 // in this nesting (i.e., the concurrent cycle). Further nesting is
652 // not currently supported. The end of the this call also notifies
653 // the FullGCCount_lock in case a Java thread is waiting for a full
654 // GC to happen (e.g., it called System.gc() with
655 // +ExplicitGCInvokesConcurrent).
656 void increment_full_collections_completed(bool concurrent);
657
658 unsigned int full_collections_completed() {
659 return _full_collections_completed;
660 }
661
662 G1HRPrinter* hr_printer() { return &_hr_printer; }
663
664 protected:
665
666 // Shrink the garbage-first heap by at most the given size (in bytes!).
667 // (Rounds down to a HeapRegion boundary.)
668 virtual void shrink(size_t expand_bytes);
669 void shrink_helper(size_t expand_bytes);
670
671 #if TASKQUEUE_STATS
672 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
673 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
674 void reset_taskqueue_stats();
675 #endif // TASKQUEUE_STATS
676
677 // Schedule the VM operation that will do an evacuation pause to
678 // satisfy an allocation request of word_size. *succeeded will
679 // return whether the VM operation was successful (it did do an
680 // evacuation pause) or not (another thread beat us to it or the GC
681 // locker was active). Given that we should not be holding the
682 // Heap_lock when we enter this method, we will pass the
683 // gc_count_before (i.e., total_collections()) as a parameter since
684 // it has to be read while holding the Heap_lock. Currently, both
685 // methods that call do_collection_pause() release the Heap_lock
686 // before the call, so it's easy to read gc_count_before just before.
687 HeapWord* do_collection_pause(size_t word_size,
688 unsigned int gc_count_before,
689 bool* succeeded);
690
691 // The guts of the incremental collection pause, executed by the vm
692 // thread. It returns false if it is unable to do the collection due
693 // to the GC locker being active, true otherwise
694 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
695
696 // Actually do the work of evacuating the collection set.
697 void evacuate_collection_set();
698
699 // The g1 remembered set of the heap.
700 G1RemSet* _g1_rem_set;
701 // And it's mod ref barrier set, used to track updates for the above.
702 ModRefBarrierSet* _mr_bs;
703
704 // A set of cards that cover the objects for which the Rsets should be updated
705 // concurrently after the collection.
706 DirtyCardQueueSet _dirty_card_queue_set;
707
708 // The Heap Region Rem Set Iterator.
709 HeapRegionRemSetIterator** _rem_set_iterator;
710
711 // The closure used to refine a single card.
712 RefineCardTableEntryClosure* _refine_cte_cl;
713
714 // A function to check the consistency of dirty card logs.
715 void check_ct_logs_at_safepoint();
716
717 // A DirtyCardQueueSet that is used to hold cards that contain
718 // references into the current collection set. This is used to
719 // update the remembered sets of the regions in the collection
720 // set in the event of an evacuation failure.
721 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
722
723 // After a collection pause, make the regions in the CS into free
724 // regions.
725 void free_collection_set(HeapRegion* cs_head);
726
727 // Abandon the current collection set without recording policy
728 // statistics or updating free lists.
729 void abandon_collection_set(HeapRegion* cs_head);
730
731 // Applies "scan_non_heap_roots" to roots outside the heap,
732 // "scan_rs" to roots inside the heap (having done "set_region" to
733 // indicate the region in which the root resides), and does "scan_perm"
734 // (setting the generation to the perm generation.) If "scan_rs" is
735 // NULL, then this step is skipped. The "worker_i"
736 // param is for use with parallel roots processing, and should be
737 // the "i" of the calling parallel worker thread's work(i) function.
738 // In the sequential case this param will be ignored.
739 void g1_process_strong_roots(bool collecting_perm_gen,
740 SharedHeap::ScanningOption so,
741 OopClosure* scan_non_heap_roots,
742 OopsInHeapRegionClosure* scan_rs,
743 OopsInGenClosure* scan_perm,
744 int worker_i);
745
746 // Apply "blk" to all the weak roots of the system. These include
747 // JNI weak roots, the code cache, system dictionary, symbol table,
748 // string table, and referents of reachable weak refs.
749 void g1_process_weak_roots(OopClosure* root_closure,
750 OopClosure* non_root_closure);
751
752 // Invoke "save_marks" on all heap regions.
753 void save_marks();
754
755 // Frees a non-humongous region by initializing its contents and
756 // adding it to the free list that's passed as a parameter (this is
757 // usually a local list which will be appended to the master free
758 // list later). The used bytes of freed regions are accumulated in
759 // pre_used. If par is true, the region's RSet will not be freed
760 // up. The assumption is that this will be done later.
761 void free_region(HeapRegion* hr,
762 size_t* pre_used,
763 FreeRegionList* free_list,
764 bool par);
765
766 // Frees a humongous region by collapsing it into individual regions
767 // and calling free_region() for each of them. The freed regions
768 // will be added to the free list that's passed as a parameter (this
769 // is usually a local list which will be appended to the master free
770 // list later). The used bytes of freed regions are accumulated in
771 // pre_used. If par is true, the region's RSet will not be freed
772 // up. The assumption is that this will be done later.
773 void free_humongous_region(HeapRegion* hr,
774 size_t* pre_used,
775 FreeRegionList* free_list,
776 HumongousRegionSet* humongous_proxy_set,
777 bool par);
778
779 // Notifies all the necessary spaces that the committed space has
780 // been updated (either expanded or shrunk). It should be called
781 // after _g1_storage is updated.
782 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
783
784 // The concurrent marker (and the thread it runs in.)
785 ConcurrentMark* _cm;
786 ConcurrentMarkThread* _cmThread;
787 bool _mark_in_progress;
788
789 // The concurrent refiner.
790 ConcurrentG1Refine* _cg1r;
791
792 // The parallel task queues
793 RefToScanQueueSet *_task_queues;
794
795 // True iff a evacuation has failed in the current collection.
796 bool _evacuation_failed;
797
798 // Set the attribute indicating whether evacuation has failed in the
799 // current collection.
800 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
801
802 // Failed evacuations cause some logical from-space objects to have
803 // forwarding pointers to themselves. Reset them.
804 void remove_self_forwarding_pointers();
805
806 // When one is non-null, so is the other. Together, they each pair is
807 // an object with a preserved mark, and its mark value.
808 GrowableArray<oop>* _objs_with_preserved_marks;
809 GrowableArray<markOop>* _preserved_marks_of_objs;
810
811 // Preserve the mark of "obj", if necessary, in preparation for its mark
812 // word being overwritten with a self-forwarding-pointer.
813 void preserve_mark_if_necessary(oop obj, markOop m);
814
815 // The stack of evac-failure objects left to be scanned.
816 GrowableArray<oop>* _evac_failure_scan_stack;
817 // The closure to apply to evac-failure objects.
818
819 OopsInHeapRegionClosure* _evac_failure_closure;
820 // Set the field above.
821 void
822 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
823 _evac_failure_closure = evac_failure_closure;
824 }
825
826 // Push "obj" on the scan stack.
827 void push_on_evac_failure_scan_stack(oop obj);
828 // Process scan stack entries until the stack is empty.
829 void drain_evac_failure_scan_stack();
830 // True iff an invocation of "drain_scan_stack" is in progress; to
831 // prevent unnecessary recursion.
832 bool _drain_in_progress;
833
834 // Do any necessary initialization for evacuation-failure handling.
835 // "cl" is the closure that will be used to process evac-failure
836 // objects.
837 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
838 // Do any necessary cleanup for evacuation-failure handling data
839 // structures.
840 void finalize_for_evac_failure();
841
842 // An attempt to evacuate "obj" has failed; take necessary steps.
843 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
844 void handle_evacuation_failure_common(oop obj, markOop m);
845
846 // Ensure that the relevant gc_alloc regions are set.
847 void get_gc_alloc_regions();
848 // We're done with GC alloc regions. We are going to tear down the
849 // gc alloc list and remove the gc alloc tag from all the regions on
850 // that list. However, we will also retain the last (i.e., the one
851 // that is half-full) GC alloc region, per GCAllocPurpose, for
852 // possible reuse during the next collection, provided
853 // _retain_gc_alloc_region[] indicates that it should be the
854 // case. Said regions are kept in the _retained_gc_alloc_regions[]
855 // array. If the parameter totally is set, we will not retain any
856 // regions, irrespective of what _retain_gc_alloc_region[]
857 // indicates.
858 void release_gc_alloc_regions(bool totally);
859 #ifndef PRODUCT
860 // Useful for debugging.
861 void print_gc_alloc_regions();
862 #endif // !PRODUCT
863
864 // ("Weak") Reference processing support.
865 //
866 // G1 has 2 instances of the referece processor class. One
867 // (_ref_processor_cm) handles reference object discovery
868 // and subsequent processing during concurrent marking cycles.
869 //
870 // The other (_ref_processor_stw) handles reference object
871 // discovery and processing during full GCs and incremental
872 // evacuation pauses.
873 //
874 // During an incremental pause, reference discovery will be
875 // temporarily disabled for _ref_processor_cm and will be
876 // enabled for _ref_processor_stw. At the end of the evacuation
877 // pause references discovered by _ref_processor_stw will be
878 // processed and discovery will be disabled. The previous
879 // setting for reference object discovery for _ref_processor_cm
880 // will be re-instated.
881 //
882 // At the start of marking:
883 // * Discovery by the CM ref processor is verified to be inactive
884 // and it's discovered lists are empty.
885 // * Discovery by the CM ref processor is then enabled.
886 //
887 // At the end of marking:
888 // * Any references on the CM ref processor's discovered
889 // lists are processed (possibly MT).
890 //
891 // At the start of full GC we:
892 // * Disable discovery by the CM ref processor and
893 // empty CM ref processor's discovered lists
894 // (without processing any entries).
895 // * Verify that the STW ref processor is inactive and it's
896 // discovered lists are empty.
897 // * Temporarily set STW ref processor discovery as single threaded.
898 // * Temporarily clear the STW ref processor's _is_alive_non_header
899 // field.
900 // * Finally enable discovery by the STW ref processor.
901 //
902 // The STW ref processor is used to record any discovered
903 // references during the full GC.
904 //
905 // At the end of a full GC we:
906 // * Will enqueue any non-live discovered references on the
907 // STW ref processor's discovered lists. This makes the
908 // STW ref processor inactive by disabling discovery.
909 // * Verify that the CM ref processor is still inactive
910 // and no references have been placed on it's discovered
911 // lists (also checked as a precondition during initial marking).
912
913 // The (stw) reference processor...
914 ReferenceProcessor* _ref_processor_stw;
915
916 // Instance of the is_alive closure for embedding into the
917 // STW reference processor as the _is_alive_non_header field.
918 // The _is_alive_non_header prevents unnecessary additions to
919 // the discovered lists during reference discovery.
920 G1STWIsAliveClosure _is_alive_closure_stw;
921
922 // The (concurrent marking) reference processor...
923 ReferenceProcessor* _ref_processor_cm;
924
925 // Instance of the concurrent mark is_alive closure for embedding
926 // into the Concurrent Marking reference processor as the
927 // _is_alive_non_header field. The _is_alive_non_header
928 // prevents unnecessary additions to the discovered lists
929 // during concurrent discovery.
930 G1CMIsAliveClosure _is_alive_closure_cm;
931
932 enum G1H_process_strong_roots_tasks {
933 G1H_PS_mark_stack_oops_do,
934 G1H_PS_refProcessor_oops_do,
935 // Leave this one last.
936 G1H_PS_NumElements
937 };
938
939 SubTasksDone* _process_strong_tasks;
940
941 volatile bool _free_regions_coming;
942
943 public:
944
945 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
946
947 void set_refine_cte_cl_concurrency(bool concurrent);
948
949 RefToScanQueue *task_queue(int i) const;
950
951 // A set of cards where updates happened during the GC
952 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
953
954 // A DirtyCardQueueSet that is used to hold cards that contain
955 // references into the current collection set. This is used to
956 // update the remembered sets of the regions in the collection
957 // set in the event of an evacuation failure.
958 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
959 { return _into_cset_dirty_card_queue_set; }
960
961 // Create a G1CollectedHeap with the specified policy.
962 // Must call the initialize method afterwards.
963 // May not return if something goes wrong.
964 G1CollectedHeap(G1CollectorPolicy* policy);
965
966 // Initialize the G1CollectedHeap to have the initial and
967 // maximum sizes, permanent generation, and remembered and barrier sets
968 // specified by the policy object.
969 jint initialize();
970
971 // Initialize weak reference processing.
972 virtual void ref_processing_init();
973
974 void set_par_threads(int t) {
975 SharedHeap::set_par_threads(t);
976 _process_strong_tasks->set_n_threads(t);
977 }
978
979 virtual CollectedHeap::Name kind() const {
980 return CollectedHeap::G1CollectedHeap;
981 }
982
983 // The current policy object for the collector.
984 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
985
986 // Adaptive size policy. No such thing for g1.
987 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
988
989 // The rem set and barrier set.
990 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
991 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
992
993 // The rem set iterator.
994 HeapRegionRemSetIterator* rem_set_iterator(int i) {
995 return _rem_set_iterator[i];
996 }
997
998 HeapRegionRemSetIterator* rem_set_iterator() {
999 return _rem_set_iterator[0];
1000 }
1001
1002 unsigned get_gc_time_stamp() {
1003 return _gc_time_stamp;
1004 }
1005
1006 void reset_gc_time_stamp() {
1007 _gc_time_stamp = 0;
1008 OrderAccess::fence();
1009 }
1010
1011 void increment_gc_time_stamp() {
1012 ++_gc_time_stamp;
1013 OrderAccess::fence();
1014 }
1015
1016 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1017 DirtyCardQueue* into_cset_dcq,
1018 bool concurrent, int 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 // The Concurent Marking reference processor...
1029 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1030
1031 virtual size_t capacity() const;
1032 virtual size_t used() const;
1033 // This should be called when we're not holding the heap lock. The
1034 // result might be a bit inaccurate.
1035 size_t used_unlocked() const;
1036 size_t recalculate_used() const;
1037 #ifndef PRODUCT
1038 size_t recalculate_used_regions() const;
1039 #endif // PRODUCT
1040
1041 // These virtual functions do the actual allocation.
1042 // Some heaps may offer a contiguous region for shared non-blocking
1043 // allocation, via inlined code (by exporting the address of the top and
1044 // end fields defining the extent of the contiguous allocation region.)
1045 // But G1CollectedHeap doesn't yet support this.
1046
1047 // Return an estimate of the maximum allocation that could be performed
1048 // without triggering any collection or expansion activity. In a
1049 // generational collector, for example, this is probably the largest
1050 // allocation that could be supported (without expansion) in the youngest
1051 // generation. It is "unsafe" because no locks are taken; the result
1052 // should be treated as an approximation, not a guarantee, for use in
1053 // heuristic resizing decisions.
1054 virtual size_t unsafe_max_alloc();
1055
1056 virtual bool is_maximal_no_gc() const {
1057 return _g1_storage.uncommitted_size() == 0;
1058 }
1059
1060 // The total number of regions in the heap.
1061 size_t n_regions() { return _hrs.length(); }
1062
1063 // The max number of regions in the heap.
1064 size_t max_regions() { return _hrs.max_length(); }
1065
1066 // The number of regions that are completely free.
1067 size_t free_regions() { return _free_list.length(); }
1068
1069 // The number of regions that are not completely free.
1070 size_t used_regions() { return n_regions() - free_regions(); }
1071
1072 // The number of regions available for "regular" expansion.
1073 size_t expansion_regions() { return _expansion_regions; }
1074
1075 // Factory method for HeapRegion instances. It will return NULL if
1076 // the allocation fails.
1077 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1078
1079 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1080 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1081 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1082 void verify_dirty_young_regions() PRODUCT_RETURN;
1083
1084 // verify_region_sets() performs verification over the region
1085 // lists. It will be compiled in the product code to be used when
1086 // necessary (i.e., during heap verification).
1087 void verify_region_sets();
1088
1089 // verify_region_sets_optional() is planted in the code for
1090 // list verification in non-product builds (and it can be enabled in
1091 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1092 #if HEAP_REGION_SET_FORCE_VERIFY
1093 void verify_region_sets_optional() {
1094 verify_region_sets();
1095 }
1096 #else // HEAP_REGION_SET_FORCE_VERIFY
1097 void verify_region_sets_optional() { }
1098 #endif // HEAP_REGION_SET_FORCE_VERIFY
1099
1100 #ifdef ASSERT
1101 bool is_on_master_free_list(HeapRegion* hr) {
1102 return hr->containing_set() == &_free_list;
1103 }
1104
1105 bool is_in_humongous_set(HeapRegion* hr) {
1106 return hr->containing_set() == &_humongous_set;
1107 }
1108 #endif // ASSERT
1109
1110 // Wrapper for the region list operations that can be called from
1111 // methods outside this class.
1112
1113 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1114 _secondary_free_list.add_as_tail(list);
1115 }
1116
1117 void append_secondary_free_list() {
1118 _free_list.add_as_head(&_secondary_free_list);
1119 }
1120
1121 void append_secondary_free_list_if_not_empty_with_lock() {
1122 // If the secondary free list looks empty there's no reason to
1123 // take the lock and then try to append it.
1124 if (!_secondary_free_list.is_empty()) {
1125 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1126 append_secondary_free_list();
1127 }
1128 }
1129
1130 void set_free_regions_coming();
1131 void reset_free_regions_coming();
1132 bool free_regions_coming() { return _free_regions_coming; }
1133 void wait_while_free_regions_coming();
1134
1135 // Perform a collection of the heap; intended for use in implementing
1136 // "System.gc". This probably implies as full a collection as the
1137 // "CollectedHeap" supports.
1138 virtual void collect(GCCause::Cause cause);
1139
1140 // The same as above but assume that the caller holds the Heap_lock.
1141 void collect_locked(GCCause::Cause cause);
1142
1143 // This interface assumes that it's being called by the
1144 // vm thread. It collects the heap assuming that the
1145 // heap lock is already held and that we are executing in
1146 // the context of the vm thread.
1147 virtual void collect_as_vm_thread(GCCause::Cause cause);
1148
1149 // True iff a evacuation has failed in the most-recent collection.
1150 bool evacuation_failed() { return _evacuation_failed; }
1151
1152 // It will free a region if it has allocated objects in it that are
1153 // all dead. It calls either free_region() or
1154 // free_humongous_region() depending on the type of the region that
1155 // is passed to it.
1156 void free_region_if_empty(HeapRegion* hr,
1157 size_t* pre_used,
1158 FreeRegionList* free_list,
1159 HumongousRegionSet* humongous_proxy_set,
1160 HRRSCleanupTask* hrrs_cleanup_task,
1161 bool par);
1162
1163 // It appends the free list to the master free list and updates the
1164 // master humongous list according to the contents of the proxy
1165 // list. It also adjusts the total used bytes according to pre_used
1166 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1167 void update_sets_after_freeing_regions(size_t pre_used,
1168 FreeRegionList* free_list,
1169 HumongousRegionSet* humongous_proxy_set,
1170 bool par);
1171
1172 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1173 virtual bool is_in(const void* p) const;
1174
1175 // Return "TRUE" iff the given object address is within the collection
1176 // set.
1177 inline bool obj_in_cs(oop obj);
1178
1179 // Return "TRUE" iff the given object address is in the reserved
1180 // region of g1 (excluding the permanent generation).
1181 bool is_in_g1_reserved(const void* p) const {
1182 return _g1_reserved.contains(p);
1183 }
1184
1185 // Returns a MemRegion that corresponds to the space that has been
1186 // reserved for the heap
1187 MemRegion g1_reserved() {
1188 return _g1_reserved;
1189 }
1190
1191 // Returns a MemRegion that corresponds to the space that has been
1192 // committed in the heap
1193 MemRegion g1_committed() {
1194 return _g1_committed;
1195 }
1196
1197 virtual bool is_in_closed_subset(const void* p) const;
1198
1199 // Dirty card table entries covering a list of young regions.
1200 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1201
1202 // This resets the card table to all zeros. It is used after
1203 // a collection pause which used the card table to claim cards.
1204 void cleanUpCardTable();
1205
1206 // Iteration functions.
1207
1208 // Iterate over all the ref-containing fields of all objects, calling
1209 // "cl.do_oop" on each.
1210 virtual void oop_iterate(OopClosure* cl) {
1211 oop_iterate(cl, true);
1212 }
1213 void oop_iterate(OopClosure* cl, bool do_perm);
1214
1215 // Same as above, restricted to a memory region.
1216 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1217 oop_iterate(mr, cl, true);
1218 }
1219 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1220
1221 // Iterate over all objects, calling "cl.do_object" on each.
1222 virtual void object_iterate(ObjectClosure* cl) {
1223 object_iterate(cl, true);
1224 }
1225 virtual void safe_object_iterate(ObjectClosure* cl) {
1226 object_iterate(cl, true);
1227 }
1228 void object_iterate(ObjectClosure* cl, bool do_perm);
1229
1230 // Iterate over all objects allocated since the last collection, calling
1231 // "cl.do_object" on each. The heap must have been initialized properly
1232 // to support this function, or else this call will fail.
1233 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1234
1235 // Iterate over all spaces in use in the heap, in ascending address order.
1236 virtual void space_iterate(SpaceClosure* cl);
1237
1238 // Iterate over heap regions, in address order, terminating the
1239 // iteration early if the "doHeapRegion" method returns "true".
1240 void heap_region_iterate(HeapRegionClosure* blk) const;
1241
1242 // Iterate over heap regions starting with r (or the first region if "r"
1243 // is NULL), in address order, terminating early if the "doHeapRegion"
1244 // method returns "true".
1245 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1246
1247 // Return the region with the given index. It assumes the index is valid.
1248 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1249
1250 // Divide the heap region sequence into "chunks" of some size (the number
1251 // of regions divided by the number of parallel threads times some
1252 // overpartition factor, currently 4). Assumes that this will be called
1253 // in parallel by ParallelGCThreads worker threads with discinct worker
1254 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1255 // calls will use the same "claim_value", and that that claim value is
1256 // different from the claim_value of any heap region before the start of
1257 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1258 // attempting to claim the first region in each chunk, and, if
1259 // successful, applying the closure to each region in the chunk (and
1260 // setting the claim value of the second and subsequent regions of the
1261 // chunk.) For now requires that "doHeapRegion" always returns "false",
1262 // i.e., that a closure never attempt to abort a traversal.
1263 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1264 int worker,
1265 jint claim_value);
1266
1267 // It resets all the region claim values to the default.
1268 void reset_heap_region_claim_values();
1269
1270 #ifdef ASSERT
1271 bool check_heap_region_claim_values(jint claim_value);
1272 #endif // ASSERT
1273
1274 // Iterate over the regions (if any) in the current collection set.
1275 void collection_set_iterate(HeapRegionClosure* blk);
1276
1277 // As above but starting from region r
1278 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1279
1280 // Returns the first (lowest address) compactible space in the heap.
1281 virtual CompactibleSpace* first_compactible_space();
1282
1283 // A CollectedHeap will contain some number of spaces. This finds the
1284 // space containing a given address, or else returns NULL.
1285 virtual Space* space_containing(const void* addr) const;
1286
1287 // A G1CollectedHeap will contain some number of heap regions. This
1288 // finds the region containing a given address, or else returns NULL.
1289 template <class T>
1290 inline HeapRegion* heap_region_containing(const T addr) const;
1291
1292 // Like the above, but requires "addr" to be in the heap (to avoid a
1293 // null-check), and unlike the above, may return an continuing humongous
1294 // region.
1295 template <class T>
1296 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1297
1298 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1299 // each address in the (reserved) heap is a member of exactly
1300 // one block. The defining characteristic of a block is that it is
1301 // possible to find its size, and thus to progress forward to the next
1302 // block. (Blocks may be of different sizes.) Thus, blocks may
1303 // represent Java objects, or they might be free blocks in a
1304 // free-list-based heap (or subheap), as long as the two kinds are
1305 // distinguishable and the size of each is determinable.
1306
1307 // Returns the address of the start of the "block" that contains the
1308 // address "addr". We say "blocks" instead of "object" since some heaps
1309 // may not pack objects densely; a chunk may either be an object or a
1310 // non-object.
1311 virtual HeapWord* block_start(const void* addr) const;
1312
1313 // Requires "addr" to be the start of a chunk, and returns its size.
1314 // "addr + size" is required to be the start of a new chunk, or the end
1315 // of the active area of the heap.
1316 virtual size_t block_size(const HeapWord* addr) const;
1317
1318 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1319 // the block is an object.
1320 virtual bool block_is_obj(const HeapWord* addr) const;
1321
1322 // Does this heap support heap inspection? (+PrintClassHistogram)
1323 virtual bool supports_heap_inspection() const { return true; }
1324
1325 // Section on thread-local allocation buffers (TLABs)
1326 // See CollectedHeap for semantics.
1327
1328 virtual bool supports_tlab_allocation() const;
1329 virtual size_t tlab_capacity(Thread* thr) const;
1330 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1331
1332 // Can a compiler initialize a new object without store barriers?
1333 // This permission only extends from the creation of a new object
1334 // via a TLAB up to the first subsequent safepoint. If such permission
1335 // is granted for this heap type, the compiler promises to call
1336 // defer_store_barrier() below on any slow path allocation of
1337 // a new object for which such initializing store barriers will
1338 // have been elided. G1, like CMS, allows this, but should be
1339 // ready to provide a compensating write barrier as necessary
1340 // if that storage came out of a non-young region. The efficiency
1341 // of this implementation depends crucially on being able to
1342 // answer very efficiently in constant time whether a piece of
1343 // storage in the heap comes from a young region or not.
1344 // See ReduceInitialCardMarks.
1345 virtual bool can_elide_tlab_store_barriers() const {
1346 // 6920090: Temporarily disabled, because of lingering
1347 // instabilities related to RICM with G1. In the
1348 // interim, the option ReduceInitialCardMarksForG1
1349 // below is left solely as a debugging device at least
1350 // until 6920109 fixes the instabilities.
1351 return ReduceInitialCardMarksForG1;
1352 }
1353
1354 virtual bool card_mark_must_follow_store() const {
1355 return true;
1356 }
1357
1358 bool is_in_young(const oop obj) {
1359 HeapRegion* hr = heap_region_containing(obj);
1360 return hr != NULL && hr->is_young();
1361 }
1362
1363 #ifdef ASSERT
1364 virtual bool is_in_partial_collection(const void* p);
1365 #endif
1366
1367 virtual bool is_scavengable(const void* addr);
1368
1369 // We don't need barriers for initializing stores to objects
1370 // in the young gen: for the SATB pre-barrier, there is no
1371 // pre-value that needs to be remembered; for the remembered-set
1372 // update logging post-barrier, we don't maintain remembered set
1373 // information for young gen objects. Note that non-generational
1374 // G1 does not have any "young" objects, should not elide
1375 // the rs logging barrier and so should always answer false below.
1376 // However, non-generational G1 (-XX:-G1Gen) appears to have
1377 // bit-rotted so was not tested below.
1378 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1379 // Re 6920090, 6920109 above.
1380 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1381 assert(G1Gen || !is_in_young(new_obj),
1382 "Non-generational G1 should never return true below");
1383 return is_in_young(new_obj);
1384 }
1385
1386 // Can a compiler elide a store barrier when it writes
1387 // a permanent oop into the heap? Applies when the compiler
1388 // is storing x to the heap, where x->is_perm() is true.
1389 virtual bool can_elide_permanent_oop_store_barriers() const {
1390 // At least until perm gen collection is also G1-ified, at
1391 // which point this should return false.
1392 return true;
1393 }
1394
1395 // Returns "true" iff the given word_size is "very large".
1396 static bool isHumongous(size_t word_size) {
1397 // Note this has to be strictly greater-than as the TLABs
1398 // are capped at the humongous thresold and we want to
1399 // ensure that we don't try to allocate a TLAB as
1400 // humongous and that we don't allocate a humongous
1401 // object in a TLAB.
1402 return word_size > _humongous_object_threshold_in_words;
1403 }
1404
1405 // Update mod union table with the set of dirty cards.
1406 void updateModUnion();
1407
1408 // Set the mod union bits corresponding to the given memRegion. Note
1409 // that this is always a safe operation, since it doesn't clear any
1410 // bits.
1411 void markModUnionRange(MemRegion mr);
1412
1413 // Records the fact that a marking phase is no longer in progress.
1414 void set_marking_complete() {
1415 _mark_in_progress = false;
1416 }
1417 void set_marking_started() {
1418 _mark_in_progress = true;
1419 }
1420 bool mark_in_progress() {
1421 return _mark_in_progress;
1422 }
1423
1424 // Print the maximum heap capacity.
1425 virtual size_t max_capacity() const;
1426
1427 virtual jlong millis_since_last_gc();
1428
1429 // Perform any cleanup actions necessary before allowing a verification.
1430 virtual void prepare_for_verify();
1431
1432 // Perform verification.
1433
1434 // vo == UsePrevMarking -> use "prev" marking information,
1435 // vo == UseNextMarking -> use "next" marking information
1436 // vo == UseMarkWord -> use the mark word in the object header
1437 //
1438 // NOTE: Only the "prev" marking information is guaranteed to be
1439 // consistent most of the time, so most calls to this should use
1440 // vo == UsePrevMarking.
1441 // Currently, there is only one case where this is called with
1442 // vo == UseNextMarking, which is to verify the "next" marking
1443 // information at the end of remark.
1444 // Currently there is only one place where this is called with
1445 // vo == UseMarkWord, which is to verify the marking during a
1446 // full GC.
1447 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1448
1449 // Override; it uses the "prev" marking information
1450 virtual void verify(bool allow_dirty, bool silent);
1451 // Default behavior by calling print(tty);
1452 virtual void print() const;
1453 // This calls print_on(st, PrintHeapAtGCExtended).
1454 virtual void print_on(outputStream* st) const;
1455 // If extended is true, it will print out information for all
1456 // regions in the heap by calling print_on_extended(st).
1457 virtual void print_on(outputStream* st, bool extended) const;
1458 virtual void print_on_extended(outputStream* st) const;
1459
1460 virtual void print_gc_threads_on(outputStream* st) const;
1461 virtual void gc_threads_do(ThreadClosure* tc) const;
1462
1463 // Override
1464 void print_tracing_info() const;
1465
1466 // The following two methods are helpful for debugging RSet issues.
1467 void print_cset_rsets() PRODUCT_RETURN;
1468 void print_all_rsets() PRODUCT_RETURN;
1469
1470 // Convenience function to be used in situations where the heap type can be
1471 // asserted to be this type.
1472 static G1CollectedHeap* heap();
1473
1474 void empty_young_list();
1475
1476 void set_region_short_lived_locked(HeapRegion* hr);
1477 // add appropriate methods for any other surv rate groups
1478
1479 YoungList* young_list() { return _young_list; }
1480
1481 // debugging
1482 bool check_young_list_well_formed() {
1483 return _young_list->check_list_well_formed();
1484 }
1485
1486 bool check_young_list_empty(bool check_heap,
1487 bool check_sample = true);
1488
1489 // *** Stuff related to concurrent marking. It's not clear to me that so
1490 // many of these need to be public.
1491
1492 // The functions below are helper functions that a subclass of
1493 // "CollectedHeap" can use in the implementation of its virtual
1494 // functions.
1495 // This performs a concurrent marking of the live objects in a
1496 // bitmap off to the side.
1497 void doConcurrentMark();
1498
1499 // Do a full concurrent marking, synchronously.
1500 void do_sync_mark();
1501
1502 bool isMarkedPrev(oop obj) const;
1503 bool isMarkedNext(oop obj) const;
1504
1505 // vo == UsePrevMarking -> use "prev" marking information,
1506 // vo == UseNextMarking -> use "next" marking information,
1507 // vo == UseMarkWord -> use mark word from object header
1508 bool is_obj_dead_cond(const oop obj,
1509 const HeapRegion* hr,
1510 const VerifyOption vo) const {
1511
1512 switch (vo) {
1513 case VerifyOption_G1UsePrevMarking:
1514 return is_obj_dead(obj, hr);
1515 case VerifyOption_G1UseNextMarking:
1516 return is_obj_ill(obj, hr);
1517 default:
1518 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1519 return !obj->is_gc_marked();
1520 }
1521 }
1522
1523 // Determine if an object is dead, given the object and also
1524 // the region to which the object belongs. An object is dead
1525 // iff a) it was not allocated since the last mark and b) it
1526 // is not marked.
1527
1528 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1529 return
1530 !hr->obj_allocated_since_prev_marking(obj) &&
1531 !isMarkedPrev(obj);
1532 }
1533
1534 // This is used when copying an object to survivor space.
1535 // If the object is marked live, then we mark the copy live.
1536 // If the object is allocated since the start of this mark
1537 // cycle, then we mark the copy live.
1538 // If the object has been around since the previous mark
1539 // phase, and hasn't been marked yet during this phase,
1540 // then we don't mark it, we just wait for the
1541 // current marking cycle to get to it.
1542
1543 // This function returns true when an object has been
1544 // around since the previous marking and hasn't yet
1545 // been marked during this marking.
1546
1547 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1548 return
1549 !hr->obj_allocated_since_next_marking(obj) &&
1550 !isMarkedNext(obj);
1551 }
1552
1553 // Determine if an object is dead, given only the object itself.
1554 // This will find the region to which the object belongs and
1555 // then call the region version of the same function.
1556
1557 // Added if it is in permanent gen it isn't dead.
1558 // Added if it is NULL it isn't dead.
1559
1560 // vo == UsePrevMarking -> use "prev" marking information,
1561 // vo == UseNextMarking -> use "next" marking information,
1562 // vo == UseMarkWord -> use mark word from object header
1563 bool is_obj_dead_cond(const oop obj,
1564 const VerifyOption vo) const {
1565
1566 switch (vo) {
1567 case VerifyOption_G1UsePrevMarking:
1568 return is_obj_dead(obj);
1569 case VerifyOption_G1UseNextMarking:
1570 return is_obj_ill(obj);
1571 default:
1572 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1573 return !obj->is_gc_marked();
1574 }
1575 }
1576
1577 bool is_obj_dead(const oop obj) const {
1578 const HeapRegion* hr = heap_region_containing(obj);
1579 if (hr == NULL) {
1580 if (Universe::heap()->is_in_permanent(obj))
1581 return false;
1582 else if (obj == NULL) return false;
1583 else return true;
1584 }
1585 else return is_obj_dead(obj, hr);
1586 }
1587
1588 bool is_obj_ill(const oop obj) const {
1589 const HeapRegion* hr = heap_region_containing(obj);
1590 if (hr == NULL) {
1591 if (Universe::heap()->is_in_permanent(obj))
1592 return false;
1593 else if (obj == NULL) return false;
1594 else return true;
1595 }
1596 else return is_obj_ill(obj, hr);
1597 }
1598
1599 // The following is just to alert the verification code
1600 // that a full collection has occurred and that the
1601 // remembered sets are no longer up to date.
1602 bool _full_collection;
1603 void set_full_collection() { _full_collection = true;}
1604 void clear_full_collection() {_full_collection = false;}
1605 bool full_collection() {return _full_collection;}
1606
1607 ConcurrentMark* concurrent_mark() const { return _cm; }
1608 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1609
1610 // The dirty cards region list is used to record a subset of regions
1611 // whose cards need clearing. The list if populated during the
1612 // remembered set scanning and drained during the card table
1613 // cleanup. Although the methods are reentrant, population/draining
1614 // phases must not overlap. For synchronization purposes the last
1615 // element on the list points to itself.
1616 HeapRegion* _dirty_cards_region_list;
1617 void push_dirty_cards_region(HeapRegion* hr);
1618 HeapRegion* pop_dirty_cards_region();
1619
1620 public:
1621 void stop_conc_gc_threads();
1622
1623 // <NEW PREDICTION>
1624
1625 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1626 void check_if_region_is_too_expensive(double predicted_time_ms);
1627 size_t pending_card_num();
1628 size_t max_pending_card_num();
1629 size_t cards_scanned();
1630
1631 // </NEW PREDICTION>
1632
1633 protected:
1634 size_t _max_heap_capacity;
1635 };
1636
1637 #define use_local_bitmaps 1
1638 #define verify_local_bitmaps 0
1639 #define oop_buffer_length 256
1640
1641 #ifndef PRODUCT
1642 class GCLabBitMap;
1643 class GCLabBitMapClosure: public BitMapClosure {
1644 private:
1645 ConcurrentMark* _cm;
1646 GCLabBitMap* _bitmap;
1647
1648 public:
1649 GCLabBitMapClosure(ConcurrentMark* cm,
1650 GCLabBitMap* bitmap) {
1651 _cm = cm;
1652 _bitmap = bitmap;
1653 }
1654
1655 virtual bool do_bit(size_t offset);
1656 };
1657 #endif // !PRODUCT
1658
1659 class GCLabBitMap: public BitMap {
1660 private:
1661 ConcurrentMark* _cm;
1662
1663 int _shifter;
1664 size_t _bitmap_word_covers_words;
1665
1666 // beginning of the heap
1667 HeapWord* _heap_start;
1668
1669 // this is the actual start of the GCLab
1670 HeapWord* _real_start_word;
1671
1672 // this is the actual end of the GCLab
1673 HeapWord* _real_end_word;
1674
1675 // this is the first word, possibly located before the actual start
1676 // of the GCLab, that corresponds to the first bit of the bitmap
1677 HeapWord* _start_word;
1678
1679 // size of a GCLab in words
1680 size_t _gclab_word_size;
1681
1682 static int shifter() {
1683 return MinObjAlignment - 1;
1684 }
1685
1686 // how many heap words does a single bitmap word corresponds to?
1687 static size_t bitmap_word_covers_words() {
1688 return BitsPerWord << shifter();
1689 }
1690
1691 size_t gclab_word_size() const {
1692 return _gclab_word_size;
1693 }
1694
1695 // Calculates actual GCLab size in words
1696 size_t gclab_real_word_size() const {
1697 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1698 / BitsPerWord;
1699 }
1700
1701 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1702 size_t bits_in_bitmap = gclab_word_size >> shifter();
1703 // We are going to ensure that the beginning of a word in this
1704 // bitmap also corresponds to the beginning of a word in the
1705 // global marking bitmap. To handle the case where a GCLab
1706 // starts from the middle of the bitmap, we need to add enough
1707 // space (i.e. up to a bitmap word) to ensure that we have
1708 // enough bits in the bitmap.
1709 return bits_in_bitmap + BitsPerWord - 1;
1710 }
1711 public:
1712 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1713 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1714 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1715 _shifter(shifter()),
1716 _bitmap_word_covers_words(bitmap_word_covers_words()),
1717 _heap_start(heap_start),
1718 _gclab_word_size(gclab_word_size),
1719 _real_start_word(NULL),
1720 _real_end_word(NULL),
1721 _start_word(NULL)
1722 {
1723 guarantee( size_in_words() >= bitmap_size_in_words(),
1724 "just making sure");
1725 }
1726
1727 inline unsigned heapWordToOffset(HeapWord* addr) {
1728 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1729 assert(offset < size(), "offset should be within bounds");
1730 return offset;
1731 }
1732
1733 inline HeapWord* offsetToHeapWord(size_t offset) {
1734 HeapWord* addr = _start_word + (offset << _shifter);
1735 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1736 return addr;
1737 }
1738
1739 bool fields_well_formed() {
1740 bool ret1 = (_real_start_word == NULL) &&
1741 (_real_end_word == NULL) &&
1742 (_start_word == NULL);
1743 if (ret1)
1744 return true;
1745
1746 bool ret2 = _real_start_word >= _start_word &&
1747 _start_word < _real_end_word &&
1748 (_real_start_word + _gclab_word_size) == _real_end_word &&
1749 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1750 > _real_end_word;
1751 return ret2;
1752 }
1753
1754 inline bool mark(HeapWord* addr) {
1755 guarantee(use_local_bitmaps, "invariant");
1756 assert(fields_well_formed(), "invariant");
1757
1758 if (addr >= _real_start_word && addr < _real_end_word) {
1759 assert(!isMarked(addr), "should not have already been marked");
1760
1761 // first mark it on the bitmap
1762 at_put(heapWordToOffset(addr), true);
1763
1764 return true;
1765 } else {
1766 return false;
1767 }
1768 }
1769
1770 inline bool isMarked(HeapWord* addr) {
1771 guarantee(use_local_bitmaps, "invariant");
1772 assert(fields_well_formed(), "invariant");
1773
1774 return at(heapWordToOffset(addr));
1775 }
1776
1777 void set_buffer(HeapWord* start) {
1778 guarantee(use_local_bitmaps, "invariant");
1779 clear();
1780
1781 assert(start != NULL, "invariant");
1782 _real_start_word = start;
1783 _real_end_word = start + _gclab_word_size;
1784
1785 size_t diff =
1786 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1787 _start_word = start - diff;
1788
1789 assert(fields_well_formed(), "invariant");
1790 }
1791
1792 #ifndef PRODUCT
1793 void verify() {
1794 // verify that the marks have been propagated
1795 GCLabBitMapClosure cl(_cm, this);
1796 iterate(&cl);
1797 }
1798 #endif // PRODUCT
1799
1800 void retire() {
1801 guarantee(use_local_bitmaps, "invariant");
1802 assert(fields_well_formed(), "invariant");
1803
1804 if (_start_word != NULL) {
1805 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1806
1807 // this means that the bitmap was set up for the GCLab
1808 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1809
1810 mark_bitmap->mostly_disjoint_range_union(this,
1811 0, // always start from the start of the bitmap
1812 _start_word,
1813 gclab_real_word_size());
1814 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1815
1816 #ifndef PRODUCT
1817 if (use_local_bitmaps && verify_local_bitmaps)
1818 verify();
1819 #endif // PRODUCT
1820 } else {
1821 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1822 }
1823 }
1824
1825 size_t bitmap_size_in_words() const {
1826 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1827 }
1828
1829 };
1830
1831 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1832 private:
1833 bool _retired;
1834 bool _during_marking;
1835 GCLabBitMap _bitmap;
1836
1837 public:
1838 G1ParGCAllocBuffer(size_t gclab_word_size) :
1839 ParGCAllocBuffer(gclab_word_size),
1840 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1841 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1842 _retired(false)
1843 { }
1844
1845 inline bool mark(HeapWord* addr) {
1846 guarantee(use_local_bitmaps, "invariant");
1847 assert(_during_marking, "invariant");
1848 return _bitmap.mark(addr);
1849 }
1850
1851 inline void set_buf(HeapWord* buf) {
1852 if (use_local_bitmaps && _during_marking)
1853 _bitmap.set_buffer(buf);
1854 ParGCAllocBuffer::set_buf(buf);
1855 _retired = false;
1856 }
1857
1858 inline void retire(bool end_of_gc, bool retain) {
1859 if (_retired)
1860 return;
1861 if (use_local_bitmaps && _during_marking) {
1862 _bitmap.retire();
1863 }
1864 ParGCAllocBuffer::retire(end_of_gc, retain);
1865 _retired = true;
1866 }
1867 };
1868
1869 class G1ParScanThreadState : public StackObj {
1870 protected:
1871 G1CollectedHeap* _g1h;
1872 RefToScanQueue* _refs;
1873 DirtyCardQueue _dcq;
1874 CardTableModRefBS* _ct_bs;
1875 G1RemSet* _g1_rem;
1876
1877 G1ParGCAllocBuffer _surviving_alloc_buffer;
1878 G1ParGCAllocBuffer _tenured_alloc_buffer;
1879 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1880 ageTable _age_table;
1881
1882 size_t _alloc_buffer_waste;
1883 size_t _undo_waste;
1884
1885 OopsInHeapRegionClosure* _evac_failure_cl;
1886 G1ParScanHeapEvacClosure* _evac_cl;
1887 G1ParScanPartialArrayClosure* _partial_scan_cl;
1888
1889 int _hash_seed;
1890 int _queue_num;
1891
1892 size_t _term_attempts;
1893
1894 double _start;
1895 double _start_strong_roots;
1896 double _strong_roots_time;
1897 double _start_term;
1898 double _term_time;
1899
1900 // Map from young-age-index (0 == not young, 1 is youngest) to
1901 // surviving words. base is what we get back from the malloc call
1902 size_t* _surviving_young_words_base;
1903 // this points into the array, as we use the first few entries for padding
1904 size_t* _surviving_young_words;
1905
1906 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1907
1908 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1909
1910 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1911
1912 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1913 CardTableModRefBS* ctbs() { return _ct_bs; }
1914
1915 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1916 if (!from->is_survivor()) {
1917 _g1_rem->par_write_ref(from, p, tid);
1918 }
1919 }
1920
1921 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1922 // If the new value of the field points to the same region or
1923 // is the to-space, we don't need to include it in the Rset updates.
1924 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1925 size_t card_index = ctbs()->index_for(p);
1926 // If the card hasn't been added to the buffer, do it.
1927 if (ctbs()->mark_card_deferred(card_index)) {
1928 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1929 }
1930 }
1931 }
1932
1933 public:
1934 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1935
1936 ~G1ParScanThreadState() {
1937 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1938 }
1939
1940 RefToScanQueue* refs() { return _refs; }
1941 ageTable* age_table() { return &_age_table; }
1942
1943 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1944 return _alloc_buffers[purpose];
1945 }
1946
1947 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1948 size_t undo_waste() const { return _undo_waste; }
1949
1950 #ifdef ASSERT
1951 bool verify_ref(narrowOop* ref) const;
1952 bool verify_ref(oop* ref) const;
1953 bool verify_task(StarTask ref) const;
1954 #endif // ASSERT
1955
1956 template <class T> void push_on_queue(T* ref) {
1957 assert(verify_ref(ref), "sanity");
1958 refs()->push(ref);
1959 }
1960
1961 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1962 if (G1DeferredRSUpdate) {
1963 deferred_rs_update(from, p, tid);
1964 } else {
1965 immediate_rs_update(from, p, tid);
1966 }
1967 }
1968
1969 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1970
1971 HeapWord* obj = NULL;
1972 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1973 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1974 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1975 assert(gclab_word_size == alloc_buf->word_sz(),
1976 "dynamic resizing is not supported");
1977 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1978 alloc_buf->retire(false, false);
1979
1980 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1981 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1982 // Otherwise.
1983 alloc_buf->set_buf(buf);
1984
1985 obj = alloc_buf->allocate(word_sz);
1986 assert(obj != NULL, "buffer was definitely big enough...");
1987 } else {
1988 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1989 }
1990 return obj;
1991 }
1992
1993 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1994 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1995 if (obj != NULL) return obj;
1996 return allocate_slow(purpose, word_sz);
1997 }
1998
1999 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
2000 if (alloc_buffer(purpose)->contains(obj)) {
2001 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2002 "should contain whole object");
2003 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2004 } else {
2005 CollectedHeap::fill_with_object(obj, word_sz);
2006 add_to_undo_waste(word_sz);
2007 }
2008 }
2009
2010 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2011 _evac_failure_cl = evac_failure_cl;
2012 }
2013 OopsInHeapRegionClosure* evac_failure_closure() {
2014 return _evac_failure_cl;
2015 }
2016
2017 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2018 _evac_cl = evac_cl;
2019 }
2020
2021 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2022 _partial_scan_cl = partial_scan_cl;
2023 }
2024
2025 int* hash_seed() { return &_hash_seed; }
2026 int queue_num() { return _queue_num; }
2027
2028 size_t term_attempts() const { return _term_attempts; }
2029 void note_term_attempt() { _term_attempts++; }
2030
2031 void start_strong_roots() {
2032 _start_strong_roots = os::elapsedTime();
2033 }
2034 void end_strong_roots() {
2035 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2036 }
2037 double strong_roots_time() const { return _strong_roots_time; }
2038
2039 void start_term_time() {
2040 note_term_attempt();
2041 _start_term = os::elapsedTime();
2042 }
2043 void end_term_time() {
2044 _term_time += (os::elapsedTime() - _start_term);
2045 }
2046 double term_time() const { return _term_time; }
2047
2048 double elapsed_time() const {
2049 return os::elapsedTime() - _start;
2050 }
2051
2052 static void
2053 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2054 void
2055 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2056
2057 size_t* surviving_young_words() {
2058 // We add on to hide entry 0 which accumulates surviving words for
2059 // age -1 regions (i.e. non-young ones)
2060 return _surviving_young_words;
2061 }
2062
2063 void retire_alloc_buffers() {
2064 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2065 size_t waste = _alloc_buffers[ap]->words_remaining();
2066 add_to_alloc_buffer_waste(waste);
2067 _alloc_buffers[ap]->retire(true, false);
2068 }
2069 }
2070
2071 template <class T> void deal_with_reference(T* ref_to_scan) {
2072 if (has_partial_array_mask(ref_to_scan)) {
2073 _partial_scan_cl->do_oop_nv(ref_to_scan);
2074 } else {
2075 // Note: we can use "raw" versions of "region_containing" because
2076 // "obj_to_scan" is definitely in the heap, and is not in a
2077 // humongous region.
2078 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2079 _evac_cl->set_region(r);
2080 _evac_cl->do_oop_nv(ref_to_scan);
2081 }
2082 }
2083
2084 void deal_with_reference(StarTask ref) {
2085 assert(verify_task(ref), "sanity");
2086 if (ref.is_narrow()) {
2087 deal_with_reference((narrowOop*)ref);
2088 } else {
2089 deal_with_reference((oop*)ref);
2090 }
2091 }
2092
2093 public:
2094 void trim_queue();
2095 };
2096
2097 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP