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 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
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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 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // refence 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 SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
179
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
188
189 class RefineCardTableEntryClosure;
190
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_GenCollectForPermanentAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
200
201 // Closures used in implementation.
202 friend class G1ParCopyHelper;
203 friend class G1IsAliveClosure;
204 friend class G1EvacuateFollowersClosure;
205 friend class G1ParScanThreadState;
206 friend class G1ParScanClosureSuper;
207 friend class G1ParEvacuateFollowersClosure;
208 friend class G1ParTask;
209 friend class G1FreeGarbageRegionClosure;
210 friend class RefineCardTableEntryClosure;
211 friend class G1PrepareCompactClosure;
212 friend class RegionSorter;
213 friend class RegionResetter;
214 friend class CountRCClosure;
215 friend class EvacPopObjClosure;
216 friend class G1ParCleanupCTTask;
217
218 // Other related classes.
219 friend class G1MarkSweep;
220
221 private:
222 // The one and only G1CollectedHeap, so static functions can find it.
223 static G1CollectedHeap* _g1h;
224
225 static size_t _humongous_object_threshold_in_words;
226
227 // Storage for the G1 heap (excludes the permanent generation).
228 VirtualSpace _g1_storage;
229 MemRegion _g1_reserved;
230
231 // The part of _g1_storage that is currently committed.
232 MemRegion _g1_committed;
233
234 // The master free list. It will satisfy all new region allocations.
235 MasterFreeRegionList _free_list;
236
237 // The secondary free list which contains regions that have been
238 // freed up during the cleanup process. This will be appended to the
239 // master free list when appropriate.
240 SecondaryFreeRegionList _secondary_free_list;
241
242 // It keeps track of the old regions.
243 MasterOldRegionSet _old_set;
244
245 // It keeps track of the humongous regions.
246 MasterHumongousRegionSet _humongous_set;
247
248 // The number of regions we could create by expansion.
249 size_t _expansion_regions;
250
251 // The block offset table for the G1 heap.
252 G1BlockOffsetSharedArray* _bot_shared;
253
254 // Tears down the region sets / lists so that they are empty and the
255 // regions on the heap do not belong to a region set / list. The
256 // only exception is the humongous set which we leave unaltered. If
257 // free_list_only is true, it will only tear down the master free
258 // list. It is called before a Full GC (free_list_only == false) or
259 // before heap shrinking (free_list_only == true).
260 void tear_down_region_sets(bool free_list_only);
261
262 // Rebuilds the region sets / lists so that they are repopulated to
263 // reflect the contents of the heap. The only exception is the
264 // humongous set which was not torn down in the first place. If
265 // free_list_only is true, it will only rebuild the master free
266 // list. It is called after a Full GC (free_list_only == false) or
267 // after heap shrinking (free_list_only == true).
268 void rebuild_region_sets(bool free_list_only);
269
270 // The sequence of all heap regions in the heap.
271 HeapRegionSeq _hrs;
272
273 // Alloc region used to satisfy mutator allocation requests.
274 MutatorAllocRegion _mutator_alloc_region;
275
276 // Alloc region used to satisfy allocation requests by the GC for
277 // survivor objects.
278 SurvivorGCAllocRegion _survivor_gc_alloc_region;
279
280 // Alloc region used to satisfy allocation requests by the GC for
281 // old objects.
282 OldGCAllocRegion _old_gc_alloc_region;
283
284 // The last old region we allocated to during the last GC.
285 // Typically, it is not full so we should re-use it during the next GC.
286 HeapRegion* _retained_old_gc_alloc_region;
287
288 // It resets the mutator alloc region before new allocations can take place.
289 void init_mutator_alloc_region();
290
291 // It releases the mutator alloc region.
292 void release_mutator_alloc_region();
293
294 // It initializes the GC alloc regions at the start of a GC.
295 void init_gc_alloc_regions();
296
297 // It releases the GC alloc regions at the end of a GC.
298 void release_gc_alloc_regions();
299
300 // It does any cleanup that needs to be done on the GC alloc regions
301 // before a Full GC.
302 void abandon_gc_alloc_regions();
303
304 // Helper for monitoring and management support.
305 G1MonitoringSupport* _g1mm;
306
307 // Determines PLAB size for a particular allocation purpose.
308 static size_t desired_plab_sz(GCAllocPurpose purpose);
309
310 // Outside of GC pauses, the number of bytes used in all regions other
311 // than the current allocation region.
312 size_t _summary_bytes_used;
313
314 // This is used for a quick test on whether a reference points into
315 // the collection set or not. Basically, we have an array, with one
316 // byte per region, and that byte denotes whether the corresponding
317 // region is in the collection set or not. The entry corresponding
318 // the bottom of the heap, i.e., region 0, is pointed to by
319 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
320 // biased so that it actually points to address 0 of the address
321 // space, to make the test as fast as possible (we can simply shift
322 // the address to address into it, instead of having to subtract the
323 // bottom of the heap from the address before shifting it; basically
324 // it works in the same way the card table works).
325 bool* _in_cset_fast_test;
326
327 // The allocated array used for the fast test on whether a reference
328 // points into the collection set or not. This field is also used to
329 // free the array.
330 bool* _in_cset_fast_test_base;
331
332 // The length of the _in_cset_fast_test_base array.
333 size_t _in_cset_fast_test_length;
334
335 volatile unsigned _gc_time_stamp;
336
337 size_t* _surviving_young_words;
338
339 G1HRPrinter _hr_printer;
340
341 void setup_surviving_young_words();
342 void update_surviving_young_words(size_t* surv_young_words);
343 void cleanup_surviving_young_words();
344
345 // It decides whether an explicit GC should start a concurrent cycle
346 // instead of doing a STW GC. Currently, a concurrent cycle is
347 // explicitly started if:
348 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
349 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
350 bool should_do_concurrent_full_gc(GCCause::Cause cause);
351
352 // Keeps track of how many "full collections" (i.e., Full GCs or
353 // concurrent cycles) we have completed. The number of them we have
354 // started is maintained in _total_full_collections in CollectedHeap.
355 volatile unsigned int _full_collections_completed;
356
357 // This is a non-product method that is helpful for testing. It is
358 // called at the end of a GC and artificially expands the heap by
359 // allocating a number of dead regions. This way we can induce very
360 // frequent marking cycles and stress the cleanup / concurrent
361 // cleanup code more (as all the regions that will be allocated by
362 // this method will be found dead by the marking cycle).
363 void allocate_dummy_regions() PRODUCT_RETURN;
364
365 // These are macros so that, if the assert fires, we get the correct
366 // line number, file, etc.
367
368 #define heap_locking_asserts_err_msg(_extra_message_) \
369 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
370 (_extra_message_), \
371 BOOL_TO_STR(Heap_lock->owned_by_self()), \
372 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
373 BOOL_TO_STR(Thread::current()->is_VM_thread()))
374
375 #define assert_heap_locked() \
376 do { \
377 assert(Heap_lock->owned_by_self(), \
378 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
379 } while (0)
380
381 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
382 do { \
383 assert(Heap_lock->owned_by_self() || \
384 (SafepointSynchronize::is_at_safepoint() && \
385 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
386 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
387 "should be at a safepoint")); \
388 } while (0)
389
390 #define assert_heap_locked_and_not_at_safepoint() \
391 do { \
392 assert(Heap_lock->owned_by_self() && \
393 !SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
395 "should not be at a safepoint")); \
396 } while (0)
397
398 #define assert_heap_not_locked() \
399 do { \
400 assert(!Heap_lock->owned_by_self(), \
401 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
402 } while (0)
403
404 #define assert_heap_not_locked_and_not_at_safepoint() \
405 do { \
406 assert(!Heap_lock->owned_by_self() && \
407 !SafepointSynchronize::is_at_safepoint(), \
408 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
409 "should not be at a safepoint")); \
410 } while (0)
411
412 #define assert_at_safepoint(_should_be_vm_thread_) \
413 do { \
414 assert(SafepointSynchronize::is_at_safepoint() && \
415 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
416 heap_locking_asserts_err_msg("should be at a safepoint")); \
417 } while (0)
418
419 #define assert_not_at_safepoint() \
420 do { \
421 assert(!SafepointSynchronize::is_at_safepoint(), \
422 heap_locking_asserts_err_msg("should not be at a safepoint")); \
423 } while (0)
424
425 protected:
426
427 // The young region list.
428 YoungList* _young_list;
429
430 // The current policy object for the collector.
431 G1CollectorPolicy* _g1_policy;
432
433 // This is the second level of trying to allocate a new region. If
434 // new_region() didn't find a region on the free_list, this call will
435 // check whether there's anything available on the
436 // secondary_free_list and/or wait for more regions to appear on
437 // that list, if _free_regions_coming is set.
438 HeapRegion* new_region_try_secondary_free_list();
439
440 // Try to allocate a single non-humongous HeapRegion sufficient for
441 // an allocation of the given word_size. If do_expand is true,
442 // attempt to expand the heap if necessary to satisfy the allocation
443 // request.
444 HeapRegion* new_region(size_t word_size, bool do_expand);
445
446 // Attempt to satisfy a humongous allocation request of the given
447 // size by finding a contiguous set of free regions of num_regions
448 // length and remove them from the master free list. Return the
449 // index of the first region or G1_NULL_HRS_INDEX if the search
450 // was unsuccessful.
451 size_t humongous_obj_allocate_find_first(size_t num_regions,
452 size_t word_size);
453
454 // Initialize a contiguous set of free regions of length num_regions
455 // and starting at index first so that they appear as a single
456 // humongous region.
457 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
458 size_t num_regions,
459 size_t word_size);
460
461 // Attempt to allocate a humongous object of the given size. Return
462 // NULL if unsuccessful.
463 HeapWord* humongous_obj_allocate(size_t word_size);
464
465 // The following two methods, allocate_new_tlab() and
466 // mem_allocate(), are the two main entry points from the runtime
467 // into the G1's allocation routines. They have the following
468 // assumptions:
469 //
470 // * They should both be called outside safepoints.
471 //
472 // * They should both be called without holding the Heap_lock.
473 //
474 // * All allocation requests for new TLABs should go to
475 // allocate_new_tlab().
476 //
477 // * All non-TLAB allocation requests should go to mem_allocate().
478 //
479 // * If either call cannot satisfy the allocation request using the
480 // current allocating region, they will try to get a new one. If
481 // this fails, they will attempt to do an evacuation pause and
482 // retry the allocation.
483 //
484 // * If all allocation attempts fail, even after trying to schedule
485 // an evacuation pause, allocate_new_tlab() will return NULL,
486 // whereas mem_allocate() will attempt a heap expansion and/or
487 // schedule a Full GC.
488 //
489 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
490 // should never be called with word_size being humongous. All
491 // humongous allocation requests should go to mem_allocate() which
492 // will satisfy them with a special path.
493
494 virtual HeapWord* allocate_new_tlab(size_t word_size);
495
496 virtual HeapWord* mem_allocate(size_t word_size,
497 bool* gc_overhead_limit_was_exceeded);
498
499 // The following three methods take a gc_count_before_ret
500 // parameter which is used to return the GC count if the method
501 // returns NULL. Given that we are required to read the GC count
502 // while holding the Heap_lock, and these paths will take the
503 // Heap_lock at some point, it's easier to get them to read the GC
504 // count while holding the Heap_lock before they return NULL instead
505 // of the caller (namely: mem_allocate()) having to also take the
506 // Heap_lock just to read the GC count.
507
508 // First-level mutator allocation attempt: try to allocate out of
509 // the mutator alloc region without taking the Heap_lock. This
510 // should only be used for non-humongous allocations.
511 inline HeapWord* attempt_allocation(size_t word_size,
512 unsigned int* gc_count_before_ret);
513
514 // Second-level mutator allocation attempt: take the Heap_lock and
515 // retry the allocation attempt, potentially scheduling a GC
516 // pause. This should only be used for non-humongous allocations.
517 HeapWord* attempt_allocation_slow(size_t word_size,
518 unsigned int* gc_count_before_ret);
519
520 // Takes the Heap_lock and attempts a humongous allocation. It can
521 // potentially schedule a GC pause.
522 HeapWord* attempt_allocation_humongous(size_t word_size,
523 unsigned int* gc_count_before_ret);
524
525 // Allocation attempt that should be called during safepoints (e.g.,
526 // at the end of a successful GC). expect_null_mutator_alloc_region
527 // specifies whether the mutator alloc region is expected to be NULL
528 // or not.
529 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
530 bool expect_null_mutator_alloc_region);
531
532 // It dirties the cards that cover the block so that so that the post
533 // write barrier never queues anything when updating objects on this
534 // block. It is assumed (and in fact we assert) that the block
535 // belongs to a young region.
536 inline void dirty_young_block(HeapWord* start, size_t word_size);
537
538 // Allocate blocks during garbage collection. Will ensure an
539 // allocation region, either by picking one or expanding the
540 // heap, and then allocate a block of the given size. The block
541 // may not be a humongous - it must fit into a single heap region.
542 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
543
544 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
545 HeapRegion* alloc_region,
546 bool par,
547 size_t word_size);
548
549 // Ensure that no further allocations can happen in "r", bearing in mind
550 // that parallel threads might be attempting allocations.
551 void par_allocate_remaining_space(HeapRegion* r);
552
553 // Allocation attempt during GC for a survivor object / PLAB.
554 inline HeapWord* survivor_attempt_allocation(size_t word_size);
555
556 // Allocation attempt during GC for an old object / PLAB.
557 inline HeapWord* old_attempt_allocation(size_t word_size);
558
559 // These methods are the "callbacks" from the G1AllocRegion class.
560
561 // For mutator alloc regions.
562 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
563 void retire_mutator_alloc_region(HeapRegion* alloc_region,
564 size_t allocated_bytes);
565
566 // For GC alloc regions.
567 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
568 GCAllocPurpose ap);
569 void retire_gc_alloc_region(HeapRegion* alloc_region,
570 size_t allocated_bytes, GCAllocPurpose ap);
571
572 // - if explicit_gc is true, the GC is for a System.gc() or a heap
573 // inspection request and should collect the entire heap
574 // - if clear_all_soft_refs is true, all soft references should be
575 // cleared during the GC
576 // - if explicit_gc is false, word_size describes the allocation that
577 // the GC should attempt (at least) to satisfy
578 // - it returns false if it is unable to do the collection due to the
579 // GC locker being active, true otherwise
580 bool do_collection(bool explicit_gc,
581 bool clear_all_soft_refs,
582 size_t word_size);
583
584 // Callback from VM_G1CollectFull operation.
585 // Perform a full collection.
586 void do_full_collection(bool clear_all_soft_refs);
587
588 // Resize the heap if necessary after a full collection. If this is
589 // after a collect-for allocation, "word_size" is the allocation size,
590 // and will be considered part of the used portion of the heap.
591 void resize_if_necessary_after_full_collection(size_t word_size);
592
593 // Callback from VM_G1CollectForAllocation operation.
594 // This function does everything necessary/possible to satisfy a
595 // failed allocation request (including collection, expansion, etc.)
596 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
597
598 // Attempting to expand the heap sufficiently
599 // to support an allocation of the given "word_size". If
600 // successful, perform the allocation and return the address of the
601 // allocated block, or else "NULL".
602 HeapWord* expand_and_allocate(size_t word_size);
603
604 // Process any reference objects discovered during
605 // an incremental evacuation pause.
606 void process_discovered_references();
607
608 // Enqueue any remaining discovered references
609 // after processing.
610 void enqueue_discovered_references();
611
612 public:
613
614 G1MonitoringSupport* g1mm() {
615 assert(_g1mm != NULL, "should have been initialized");
616 return _g1mm;
617 }
618
619 // Expand the garbage-first heap by at least the given size (in bytes!).
620 // Returns true if the heap was expanded by the requested amount;
621 // false otherwise.
622 // (Rounds up to a HeapRegion boundary.)
623 bool expand(size_t expand_bytes);
624
625 // Do anything common to GC's.
626 virtual void gc_prologue(bool full);
627 virtual void gc_epilogue(bool full);
628
629 // We register a region with the fast "in collection set" test. We
630 // simply set to true the array slot corresponding to this region.
631 void register_region_with_in_cset_fast_test(HeapRegion* r) {
632 assert(_in_cset_fast_test_base != NULL, "sanity");
633 assert(r->in_collection_set(), "invariant");
634 size_t index = r->hrs_index();
635 assert(index < _in_cset_fast_test_length, "invariant");
636 assert(!_in_cset_fast_test_base[index], "invariant");
637 _in_cset_fast_test_base[index] = true;
638 }
639
640 // This is a fast test on whether a reference points into the
641 // collection set or not. It does not assume that the reference
642 // points into the heap; if it doesn't, it will return false.
643 bool in_cset_fast_test(oop obj) {
644 assert(_in_cset_fast_test != NULL, "sanity");
645 if (_g1_committed.contains((HeapWord*) obj)) {
646 // no need to subtract the bottom of the heap from obj,
647 // _in_cset_fast_test is biased
648 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
649 bool ret = _in_cset_fast_test[index];
650 // let's make sure the result is consistent with what the slower
651 // test returns
652 assert( ret || !obj_in_cs(obj), "sanity");
653 assert(!ret || obj_in_cs(obj), "sanity");
654 return ret;
655 } else {
656 return false;
657 }
658 }
659
660 void clear_cset_fast_test() {
661 assert(_in_cset_fast_test_base != NULL, "sanity");
662 memset(_in_cset_fast_test_base, false,
663 _in_cset_fast_test_length * sizeof(bool));
664 }
665
666 // This is called at the end of either a concurrent cycle or a Full
667 // GC to update the number of full collections completed. Those two
668 // can happen in a nested fashion, i.e., we start a concurrent
669 // cycle, a Full GC happens half-way through it which ends first,
670 // and then the cycle notices that a Full GC happened and ends
671 // too. The concurrent parameter is a boolean to help us do a bit
672 // tighter consistency checking in the method. If concurrent is
673 // false, the caller is the inner caller in the nesting (i.e., the
674 // Full GC). If concurrent is true, the caller is the outer caller
675 // in this nesting (i.e., the concurrent cycle). Further nesting is
676 // not currently supported. The end of the this call also notifies
677 // the FullGCCount_lock in case a Java thread is waiting for a full
678 // GC to happen (e.g., it called System.gc() with
679 // +ExplicitGCInvokesConcurrent).
680 void increment_full_collections_completed(bool concurrent);
681
682 unsigned int full_collections_completed() {
683 return _full_collections_completed;
684 }
685
686 G1HRPrinter* hr_printer() { return &_hr_printer; }
687
688 protected:
689
690 // Shrink the garbage-first heap by at most the given size (in bytes!).
691 // (Rounds down to a HeapRegion boundary.)
692 virtual void shrink(size_t expand_bytes);
693 void shrink_helper(size_t expand_bytes);
694
695 #if TASKQUEUE_STATS
696 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
697 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
698 void reset_taskqueue_stats();
699 #endif // TASKQUEUE_STATS
700
701 // Schedule the VM operation that will do an evacuation pause to
702 // satisfy an allocation request of word_size. *succeeded will
703 // return whether the VM operation was successful (it did do an
704 // evacuation pause) or not (another thread beat us to it or the GC
705 // locker was active). Given that we should not be holding the
706 // Heap_lock when we enter this method, we will pass the
707 // gc_count_before (i.e., total_collections()) as a parameter since
708 // it has to be read while holding the Heap_lock. Currently, both
709 // methods that call do_collection_pause() release the Heap_lock
710 // before the call, so it's easy to read gc_count_before just before.
711 HeapWord* do_collection_pause(size_t word_size,
712 unsigned int gc_count_before,
713 bool* succeeded);
714
715 // The guts of the incremental collection pause, executed by the vm
716 // thread. It returns false if it is unable to do the collection due
717 // to the GC locker being active, true otherwise
718 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
719
720 // Actually do the work of evacuating the collection set.
721 void evacuate_collection_set();
722
723 // The g1 remembered set of the heap.
724 G1RemSet* _g1_rem_set;
725 // And it's mod ref barrier set, used to track updates for the above.
726 ModRefBarrierSet* _mr_bs;
727
728 // A set of cards that cover the objects for which the Rsets should be updated
729 // concurrently after the collection.
730 DirtyCardQueueSet _dirty_card_queue_set;
731
732 // The Heap Region Rem Set Iterator.
733 HeapRegionRemSetIterator** _rem_set_iterator;
734
735 // The closure used to refine a single card.
736 RefineCardTableEntryClosure* _refine_cte_cl;
737
738 // A function to check the consistency of dirty card logs.
739 void check_ct_logs_at_safepoint();
740
741 // A DirtyCardQueueSet that is used to hold cards that contain
742 // references into the current collection set. This is used to
743 // update the remembered sets of the regions in the collection
744 // set in the event of an evacuation failure.
745 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
746
747 // After a collection pause, make the regions in the CS into free
748 // regions.
749 void free_collection_set(HeapRegion* cs_head);
750
751 // Abandon the current collection set without recording policy
752 // statistics or updating free lists.
753 void abandon_collection_set(HeapRegion* cs_head);
754
755 // Applies "scan_non_heap_roots" to roots outside the heap,
756 // "scan_rs" to roots inside the heap (having done "set_region" to
757 // indicate the region in which the root resides), and does "scan_perm"
758 // (setting the generation to the perm generation.) If "scan_rs" is
759 // NULL, then this step is skipped. The "worker_i"
760 // param is for use with parallel roots processing, and should be
761 // the "i" of the calling parallel worker thread's work(i) function.
762 // In the sequential case this param will be ignored.
763 void g1_process_strong_roots(bool collecting_perm_gen,
764 SharedHeap::ScanningOption so,
765 OopClosure* scan_non_heap_roots,
766 OopsInHeapRegionClosure* scan_rs,
767 OopsInGenClosure* scan_perm,
768 int worker_i);
769
770 // Apply "blk" to all the weak roots of the system. These include
771 // JNI weak roots, the code cache, system dictionary, symbol table,
772 // string table, and referents of reachable weak refs.
773 void g1_process_weak_roots(OopClosure* root_closure,
774 OopClosure* non_root_closure);
775
776 // Frees a non-humongous region by initializing its contents and
777 // adding it to the free list that's passed as a parameter (this is
778 // usually a local list which will be appended to the master free
779 // list later). The used bytes of freed regions are accumulated in
780 // pre_used. If par is true, the region's RSet will not be freed
781 // up. The assumption is that this will be done later.
782 void free_region(HeapRegion* hr,
783 size_t* pre_used,
784 FreeRegionList* free_list,
785 bool par);
786
787 // Frees a humongous region by collapsing it into individual regions
788 // and calling free_region() for each of them. The freed regions
789 // will be added to the free list that's passed as a parameter (this
790 // is usually a local list which will be appended to the master free
791 // list later). The used bytes of freed regions are accumulated in
792 // pre_used. If par is true, the region's RSet will not be freed
793 // up. The assumption is that this will be done later.
794 void free_humongous_region(HeapRegion* hr,
795 size_t* pre_used,
796 FreeRegionList* free_list,
797 HumongousRegionSet* humongous_proxy_set,
798 bool par);
799
800 // Notifies all the necessary spaces that the committed space has
801 // been updated (either expanded or shrunk). It should be called
802 // after _g1_storage is updated.
803 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
804
805 // The concurrent marker (and the thread it runs in.)
806 ConcurrentMark* _cm;
807 ConcurrentMarkThread* _cmThread;
808 bool _mark_in_progress;
809
810 // The concurrent refiner.
811 ConcurrentG1Refine* _cg1r;
812
813 // The parallel task queues
814 RefToScanQueueSet *_task_queues;
815
816 // True iff a evacuation has failed in the current collection.
817 bool _evacuation_failed;
818
819 // Set the attribute indicating whether evacuation has failed in the
820 // current collection.
821 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
822
823 // Failed evacuations cause some logical from-space objects to have
824 // forwarding pointers to themselves. Reset them.
825 void remove_self_forwarding_pointers();
826
827 // When one is non-null, so is the other. Together, they each pair is
828 // an object with a preserved mark, and its mark value.
829 GrowableArray<oop>* _objs_with_preserved_marks;
830 GrowableArray<markOop>* _preserved_marks_of_objs;
831
832 // Preserve the mark of "obj", if necessary, in preparation for its mark
833 // word being overwritten with a self-forwarding-pointer.
834 void preserve_mark_if_necessary(oop obj, markOop m);
835
836 // The stack of evac-failure objects left to be scanned.
837 GrowableArray<oop>* _evac_failure_scan_stack;
838 // The closure to apply to evac-failure objects.
839
840 OopsInHeapRegionClosure* _evac_failure_closure;
841 // Set the field above.
842 void
843 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
844 _evac_failure_closure = evac_failure_closure;
845 }
846
847 // Push "obj" on the scan stack.
848 void push_on_evac_failure_scan_stack(oop obj);
849 // Process scan stack entries until the stack is empty.
850 void drain_evac_failure_scan_stack();
851 // True iff an invocation of "drain_scan_stack" is in progress; to
852 // prevent unnecessary recursion.
853 bool _drain_in_progress;
854
855 // Do any necessary initialization for evacuation-failure handling.
856 // "cl" is the closure that will be used to process evac-failure
857 // objects.
858 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
859 // Do any necessary cleanup for evacuation-failure handling data
860 // structures.
861 void finalize_for_evac_failure();
862
863 // An attempt to evacuate "obj" has failed; take necessary steps.
864 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj,
865 bool should_mark_root);
866 void handle_evacuation_failure_common(oop obj, markOop m);
867
868 // ("Weak") Reference processing support.
869 //
870 // G1 has 2 instances of the referece processor class. One
871 // (_ref_processor_cm) handles reference object discovery
872 // and subsequent processing during concurrent marking cycles.
873 //
874 // The other (_ref_processor_stw) handles reference object
875 // discovery and processing during full GCs and incremental
876 // evacuation pauses.
877 //
878 // During an incremental pause, reference discovery will be
879 // temporarily disabled for _ref_processor_cm and will be
880 // enabled for _ref_processor_stw. At the end of the evacuation
881 // pause references discovered by _ref_processor_stw will be
882 // processed and discovery will be disabled. The previous
883 // setting for reference object discovery for _ref_processor_cm
884 // will be re-instated.
885 //
886 // At the start of marking:
887 // * Discovery by the CM ref processor is verified to be inactive
888 // and it's discovered lists are empty.
889 // * Discovery by the CM ref processor is then enabled.
890 //
891 // At the end of marking:
892 // * Any references on the CM ref processor's discovered
893 // lists are processed (possibly MT).
894 //
895 // At the start of full GC we:
896 // * Disable discovery by the CM ref processor and
897 // empty CM ref processor's discovered lists
898 // (without processing any entries).
899 // * Verify that the STW ref processor is inactive and it's
900 // discovered lists are empty.
901 // * Temporarily set STW ref processor discovery as single threaded.
902 // * Temporarily clear the STW ref processor's _is_alive_non_header
903 // field.
904 // * Finally enable discovery by the STW ref processor.
905 //
906 // The STW ref processor is used to record any discovered
907 // references during the full GC.
908 //
909 // At the end of a full GC we:
910 // * Enqueue any reference objects discovered by the STW ref processor
911 // that have non-live referents. This has the side-effect of
912 // making the STW ref processor inactive by disabling discovery.
913 // * Verify that the CM ref processor is still inactive
914 // and no references have been placed on it's discovered
915 // lists (also checked as a precondition during initial marking).
916
917 // The (stw) reference processor...
918 ReferenceProcessor* _ref_processor_stw;
919
920 // During reference object discovery, the _is_alive_non_header
921 // closure (if non-null) is applied to the referent object to
922 // determine whether the referent is live. If so then the
923 // reference object does not need to be 'discovered' and can
924 // be treated as a regular oop. This has the benefit of reducing
925 // the number of 'discovered' reference objects that need to
926 // be processed.
927 //
928 // Instance of the is_alive closure for embedding into the
929 // STW reference processor as the _is_alive_non_header field.
930 // Supplying a value for the _is_alive_non_header field is
931 // optional but doing so prevents unnecessary additions to
932 // the discovered lists during reference discovery.
933 G1STWIsAliveClosure _is_alive_closure_stw;
934
935 // The (concurrent marking) reference processor...
936 ReferenceProcessor* _ref_processor_cm;
937
938 // Instance of the concurrent mark is_alive closure for embedding
939 // into the Concurrent Marking reference processor as the
940 // _is_alive_non_header field. Supplying a value for the
941 // _is_alive_non_header field is optional but doing so prevents
942 // unnecessary additions to the discovered lists during reference
943 // discovery.
944 G1CMIsAliveClosure _is_alive_closure_cm;
945
946 enum G1H_process_strong_roots_tasks {
947 G1H_PS_mark_stack_oops_do,
948 G1H_PS_refProcessor_oops_do,
949 // Leave this one last.
950 G1H_PS_NumElements
951 };
952
953 SubTasksDone* _process_strong_tasks;
954
955 volatile bool _free_regions_coming;
956
957 public:
958
959 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
960
961 void set_refine_cte_cl_concurrency(bool concurrent);
962
963 RefToScanQueue *task_queue(int i) const;
964
965 // A set of cards where updates happened during the GC
966 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
967
968 // A DirtyCardQueueSet that is used to hold cards that contain
969 // references into the current collection set. This is used to
970 // update the remembered sets of the regions in the collection
971 // set in the event of an evacuation failure.
972 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
973 { return _into_cset_dirty_card_queue_set; }
974
975 // Create a G1CollectedHeap with the specified policy.
976 // Must call the initialize method afterwards.
977 // May not return if something goes wrong.
978 G1CollectedHeap(G1CollectorPolicy* policy);
979
980 // Initialize the G1CollectedHeap to have the initial and
981 // maximum sizes, permanent generation, and remembered and barrier sets
982 // specified by the policy object.
983 jint initialize();
984
985 // Initialize weak reference processing.
986 virtual void ref_processing_init();
987
988 void set_par_threads(int t) {
989 SharedHeap::set_par_threads(t);
990 // Done in SharedHeap but oddly there are
991 // two _process_strong_tasks's in a G1CollectedHeap
992 // so do it here too.
993 _process_strong_tasks->set_n_threads(t);
994 }
995
996 // Set _n_par_threads according to a policy TBD.
997 void set_par_threads();
998
999 void set_n_termination(int t) {
1000 _process_strong_tasks->set_n_threads(t);
1001 }
1002
1003 virtual CollectedHeap::Name kind() const {
1004 return CollectedHeap::G1CollectedHeap;
1005 }
1006
1007 // The current policy object for the collector.
1008 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1009
1010 // Adaptive size policy. No such thing for g1.
1011 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1012
1013 // The rem set and barrier set.
1014 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1015 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1016
1017 // The rem set iterator.
1018 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1019 return _rem_set_iterator[i];
1020 }
1021
1022 HeapRegionRemSetIterator* rem_set_iterator() {
1023 return _rem_set_iterator[0];
1024 }
1025
1026 unsigned get_gc_time_stamp() {
1027 return _gc_time_stamp;
1028 }
1029
1030 void reset_gc_time_stamp() {
1031 _gc_time_stamp = 0;
1032 OrderAccess::fence();
1033 }
1034
1035 void increment_gc_time_stamp() {
1036 ++_gc_time_stamp;
1037 OrderAccess::fence();
1038 }
1039
1040 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1041 DirtyCardQueue* into_cset_dcq,
1042 bool concurrent, int worker_i);
1043
1044 // The shared block offset table array.
1045 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1046
1047 // Reference Processing accessors
1048
1049 // The STW reference processor....
1050 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1051
1052 // The Concurent Marking reference processor...
1053 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1054
1055 virtual size_t capacity() const;
1056 virtual size_t used() const;
1057 // This should be called when we're not holding the heap lock. The
1058 // result might be a bit inaccurate.
1059 size_t used_unlocked() const;
1060 size_t recalculate_used() const;
1061
1062 // These virtual functions do the actual allocation.
1063 // Some heaps may offer a contiguous region for shared non-blocking
1064 // allocation, via inlined code (by exporting the address of the top and
1065 // end fields defining the extent of the contiguous allocation region.)
1066 // But G1CollectedHeap doesn't yet support this.
1067
1068 // Return an estimate of the maximum allocation that could be performed
1069 // without triggering any collection or expansion activity. In a
1070 // generational collector, for example, this is probably the largest
1071 // allocation that could be supported (without expansion) in the youngest
1072 // generation. It is "unsafe" because no locks are taken; the result
1073 // should be treated as an approximation, not a guarantee, for use in
1074 // heuristic resizing decisions.
1075 virtual size_t unsafe_max_alloc();
1076
1077 virtual bool is_maximal_no_gc() const {
1078 return _g1_storage.uncommitted_size() == 0;
1079 }
1080
1081 // The total number of regions in the heap.
1082 size_t n_regions() { return _hrs.length(); }
1083
1084 // The max number of regions in the heap.
1085 size_t max_regions() { return _hrs.max_length(); }
1086
1087 // The number of regions that are completely free.
1088 size_t free_regions() { return _free_list.length(); }
1089
1090 // The number of regions that are not completely free.
1091 size_t used_regions() { return n_regions() - free_regions(); }
1092
1093 // The number of regions available for "regular" expansion.
1094 size_t expansion_regions() { return _expansion_regions; }
1095
1096 // Factory method for HeapRegion instances. It will return NULL if
1097 // the allocation fails.
1098 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1099
1100 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1101 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1102 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1103 void verify_dirty_young_regions() PRODUCT_RETURN;
1104
1105 // verify_region_sets() performs verification over the region
1106 // lists. It will be compiled in the product code to be used when
1107 // necessary (i.e., during heap verification).
1108 void verify_region_sets();
1109
1110 // verify_region_sets_optional() is planted in the code for
1111 // list verification in non-product builds (and it can be enabled in
1112 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1113 #if HEAP_REGION_SET_FORCE_VERIFY
1114 void verify_region_sets_optional() {
1115 verify_region_sets();
1116 }
1117 #else // HEAP_REGION_SET_FORCE_VERIFY
1118 void verify_region_sets_optional() { }
1119 #endif // HEAP_REGION_SET_FORCE_VERIFY
1120
1121 #ifdef ASSERT
1122 bool is_on_master_free_list(HeapRegion* hr) {
1123 return hr->containing_set() == &_free_list;
1124 }
1125
1126 bool is_in_humongous_set(HeapRegion* hr) {
1127 return hr->containing_set() == &_humongous_set;
1128 }
1129 #endif // ASSERT
1130
1131 // Wrapper for the region list operations that can be called from
1132 // methods outside this class.
1133
1134 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1135 _secondary_free_list.add_as_tail(list);
1136 }
1137
1138 void append_secondary_free_list() {
1139 _free_list.add_as_head(&_secondary_free_list);
1140 }
1141
1142 void append_secondary_free_list_if_not_empty_with_lock() {
1143 // If the secondary free list looks empty there's no reason to
1144 // take the lock and then try to append it.
1145 if (!_secondary_free_list.is_empty()) {
1146 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1147 append_secondary_free_list();
1148 }
1149 }
1150
1151 void old_set_remove(HeapRegion* hr) {
1152 _old_set.remove(hr);
1153 }
1154
1155 void set_free_regions_coming();
1156 void reset_free_regions_coming();
1157 bool free_regions_coming() { return _free_regions_coming; }
1158 void wait_while_free_regions_coming();
1159
1160 // Perform a collection of the heap; intended for use in implementing
1161 // "System.gc". This probably implies as full a collection as the
1162 // "CollectedHeap" supports.
1163 virtual void collect(GCCause::Cause cause);
1164
1165 // The same as above but assume that the caller holds the Heap_lock.
1166 void collect_locked(GCCause::Cause cause);
1167
1168 // This interface assumes that it's being called by the
1169 // vm thread. It collects the heap assuming that the
1170 // heap lock is already held and that we are executing in
1171 // the context of the vm thread.
1172 virtual void collect_as_vm_thread(GCCause::Cause cause);
1173
1174 // True iff a evacuation has failed in the most-recent collection.
1175 bool evacuation_failed() { return _evacuation_failed; }
1176
1177 // It will free a region if it has allocated objects in it that are
1178 // all dead. It calls either free_region() or
1179 // free_humongous_region() depending on the type of the region that
1180 // is passed to it.
1181 void free_region_if_empty(HeapRegion* hr,
1182 size_t* pre_used,
1183 FreeRegionList* free_list,
1184 OldRegionSet* old_proxy_set,
1185 HumongousRegionSet* humongous_proxy_set,
1186 HRRSCleanupTask* hrrs_cleanup_task,
1187 bool par);
1188
1189 // It appends the free list to the master free list and updates the
1190 // master humongous list according to the contents of the proxy
1191 // list. It also adjusts the total used bytes according to pre_used
1192 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1193 void update_sets_after_freeing_regions(size_t pre_used,
1194 FreeRegionList* free_list,
1195 OldRegionSet* old_proxy_set,
1196 HumongousRegionSet* humongous_proxy_set,
1197 bool par);
1198
1199 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1200 virtual bool is_in(const void* p) const;
1201
1202 // Return "TRUE" iff the given object address is within the collection
1203 // set.
1204 inline bool obj_in_cs(oop obj);
1205
1206 // Return "TRUE" iff the given object address is in the reserved
1207 // region of g1 (excluding the permanent generation).
1208 bool is_in_g1_reserved(const void* p) const {
1209 return _g1_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() {
1215 return _g1_reserved;
1216 }
1217
1218 // Returns a MemRegion that corresponds to the space that has been
1219 // committed in the heap
1220 MemRegion g1_committed() {
1221 return _g1_committed;
1222 }
1223
1224 virtual bool is_in_closed_subset(const void* p) const;
1225
1226 // This resets the card table to all zeros. It is used after
1227 // a collection pause which used the card table to claim cards.
1228 void cleanUpCardTable();
1229
1230 // Iteration functions.
1231
1232 // Iterate over all the ref-containing fields of all objects, calling
1233 // "cl.do_oop" on each.
1234 virtual void oop_iterate(OopClosure* cl) {
1235 oop_iterate(cl, true);
1236 }
1237 void oop_iterate(OopClosure* cl, bool do_perm);
1238
1239 // Same as above, restricted to a memory region.
1240 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1241 oop_iterate(mr, cl, true);
1242 }
1243 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1244
1245 // Iterate over all objects, calling "cl.do_object" on each.
1246 virtual void object_iterate(ObjectClosure* cl) {
1247 object_iterate(cl, true);
1248 }
1249 virtual void safe_object_iterate(ObjectClosure* cl) {
1250 object_iterate(cl, true);
1251 }
1252 void object_iterate(ObjectClosure* cl, bool do_perm);
1253
1254 // Iterate over all objects allocated since the last collection, calling
1255 // "cl.do_object" on each. The heap must have been initialized properly
1256 // to support this function, or else this call will fail.
1257 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1258
1259 // Iterate over all spaces in use in the heap, in ascending address order.
1260 virtual void space_iterate(SpaceClosure* cl);
1261
1262 // Iterate over heap regions, in address order, terminating the
1263 // iteration early if the "doHeapRegion" method returns "true".
1264 void heap_region_iterate(HeapRegionClosure* blk) const;
1265
1266 // Iterate over heap regions starting with r (or the first region if "r"
1267 // is NULL), in address order, terminating early if the "doHeapRegion"
1268 // method returns "true".
1269 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1270
1271 // Return the region with the given index. It assumes the index is valid.
1272 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1273
1274 // Divide the heap region sequence into "chunks" of some size (the number
1275 // of regions divided by the number of parallel threads times some
1276 // overpartition factor, currently 4). Assumes that this will be called
1277 // in parallel by ParallelGCThreads worker threads with discinct worker
1278 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1279 // calls will use the same "claim_value", and that that claim value is
1280 // different from the claim_value of any heap region before the start of
1281 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1282 // attempting to claim the first region in each chunk, and, if
1283 // successful, applying the closure to each region in the chunk (and
1284 // setting the claim value of the second and subsequent regions of the
1285 // chunk.) For now requires that "doHeapRegion" always returns "false",
1286 // i.e., that a closure never attempt to abort a traversal.
1287 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1288 int worker,
1289 int no_of_par_workers,
1290 jint claim_value);
1291
1292 // It resets all the region claim values to the default.
1293 void reset_heap_region_claim_values();
1294
1295 #ifdef ASSERT
1296 bool check_heap_region_claim_values(jint claim_value);
1297
1298 // Same as the routine above but only checks regions in the
1299 // current collection set.
1300 bool check_cset_heap_region_claim_values(jint claim_value);
1301 #endif // ASSERT
1302
1303 // Given the id of a worker, calculate a suitable
1304 // starting region for iterating over the current
1305 // collection set.
1306 HeapRegion* start_cset_region_for_worker(int worker_i);
1307
1308 // Iterate over the regions (if any) in the current collection set.
1309 void collection_set_iterate(HeapRegionClosure* blk);
1310
1311 // As above but starting from region r
1312 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1313
1314 // Returns the first (lowest address) compactible space in the heap.
1315 virtual CompactibleSpace* first_compactible_space();
1316
1317 // A CollectedHeap will contain some number of spaces. This finds the
1318 // space containing a given address, or else returns NULL.
1319 virtual Space* space_containing(const void* addr) const;
1320
1321 // A G1CollectedHeap will contain some number of heap regions. This
1322 // finds the region containing a given address, or else returns NULL.
1323 template <class T>
1324 inline HeapRegion* heap_region_containing(const T addr) const;
1325
1326 // Like the above, but requires "addr" to be in the heap (to avoid a
1327 // null-check), and unlike the above, may return an continuing humongous
1328 // region.
1329 template <class T>
1330 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1331
1332 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1333 // each address in the (reserved) heap is a member of exactly
1334 // one block. The defining characteristic of a block is that it is
1335 // possible to find its size, and thus to progress forward to the next
1336 // block. (Blocks may be of different sizes.) Thus, blocks may
1337 // represent Java objects, or they might be free blocks in a
1338 // free-list-based heap (or subheap), as long as the two kinds are
1339 // distinguishable and the size of each is determinable.
1340
1341 // Returns the address of the start of the "block" that contains the
1342 // address "addr". We say "blocks" instead of "object" since some heaps
1343 // may not pack objects densely; a chunk may either be an object or a
1344 // non-object.
1345 virtual HeapWord* block_start(const void* addr) const;
1346
1347 // Requires "addr" to be the start of a chunk, and returns its size.
1348 // "addr + size" is required to be the start of a new chunk, or the end
1349 // of the active area of the heap.
1350 virtual size_t block_size(const HeapWord* addr) const;
1351
1352 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1353 // the block is an object.
1354 virtual bool block_is_obj(const HeapWord* addr) const;
1355
1356 // Does this heap support heap inspection? (+PrintClassHistogram)
1357 virtual bool supports_heap_inspection() const { return true; }
1358
1359 // Section on thread-local allocation buffers (TLABs)
1360 // See CollectedHeap for semantics.
1361
1362 virtual bool supports_tlab_allocation() const;
1363 virtual size_t tlab_capacity(Thread* thr) const;
1364 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1365
1366 // Can a compiler initialize a new object without store barriers?
1367 // This permission only extends from the creation of a new object
1368 // via a TLAB up to the first subsequent safepoint. If such permission
1369 // is granted for this heap type, the compiler promises to call
1370 // defer_store_barrier() below on any slow path allocation of
1371 // a new object for which such initializing store barriers will
1372 // have been elided. G1, like CMS, allows this, but should be
1373 // ready to provide a compensating write barrier as necessary
1374 // if that storage came out of a non-young region. The efficiency
1375 // of this implementation depends crucially on being able to
1376 // answer very efficiently in constant time whether a piece of
1377 // storage in the heap comes from a young region or not.
1378 // See ReduceInitialCardMarks.
1379 virtual bool can_elide_tlab_store_barriers() const {
1380 return true;
1381 }
1382
1383 virtual bool card_mark_must_follow_store() const {
1384 return true;
1385 }
1386
1387 bool is_in_young(const oop obj) {
1388 HeapRegion* hr = heap_region_containing(obj);
1389 return hr != NULL && hr->is_young();
1390 }
1391
1392 #ifdef ASSERT
1393 virtual bool is_in_partial_collection(const void* p);
1394 #endif
1395
1396 virtual bool is_scavengable(const void* addr);
1397
1398 // We don't need barriers for initializing stores to objects
1399 // in the young gen: for the SATB pre-barrier, there is no
1400 // pre-value that needs to be remembered; for the remembered-set
1401 // update logging post-barrier, we don't maintain remembered set
1402 // information for young gen objects.
1403 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1404 return is_in_young(new_obj);
1405 }
1406
1407 // Can a compiler elide a store barrier when it writes
1408 // a permanent oop into the heap? Applies when the compiler
1409 // is storing x to the heap, where x->is_perm() is true.
1410 virtual bool can_elide_permanent_oop_store_barriers() const {
1411 // At least until perm gen collection is also G1-ified, at
1412 // which point this should return false.
1413 return true;
1414 }
1415
1416 // Returns "true" iff the given word_size is "very large".
1417 static bool isHumongous(size_t word_size) {
1418 // Note this has to be strictly greater-than as the TLABs
1419 // are capped at the humongous thresold and we want to
1420 // ensure that we don't try to allocate a TLAB as
1421 // humongous and that we don't allocate a humongous
1422 // object in a TLAB.
1423 return word_size > _humongous_object_threshold_in_words;
1424 }
1425
1426 // Update mod union table with the set of dirty cards.
1427 void updateModUnion();
1428
1429 // Set the mod union bits corresponding to the given memRegion. Note
1430 // that this is always a safe operation, since it doesn't clear any
1431 // bits.
1432 void markModUnionRange(MemRegion mr);
1433
1434 // Records the fact that a marking phase is no longer in progress.
1435 void set_marking_complete() {
1436 _mark_in_progress = false;
1437 }
1438 void set_marking_started() {
1439 _mark_in_progress = true;
1440 }
1441 bool mark_in_progress() {
1442 return _mark_in_progress;
1443 }
1444
1445 // Print the maximum heap capacity.
1446 virtual size_t max_capacity() const;
1447
1448 virtual jlong millis_since_last_gc();
1449
1450 // Perform any cleanup actions necessary before allowing a verification.
1451 virtual void prepare_for_verify();
1452
1453 // Perform verification.
1454
1455 // vo == UsePrevMarking -> use "prev" marking information,
1456 // vo == UseNextMarking -> use "next" marking information
1457 // vo == UseMarkWord -> use the mark word in the object header
1458 //
1459 // NOTE: Only the "prev" marking information is guaranteed to be
1460 // consistent most of the time, so most calls to this should use
1461 // vo == UsePrevMarking.
1462 // Currently, there is only one case where this is called with
1463 // vo == UseNextMarking, which is to verify the "next" marking
1464 // information at the end of remark.
1465 // Currently there is only one place where this is called with
1466 // vo == UseMarkWord, which is to verify the marking during a
1467 // full GC.
1468 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1469
1470 // Override; it uses the "prev" marking information
1471 virtual void verify(bool allow_dirty, bool silent);
1472 virtual void print_on(outputStream* st) const;
1473 virtual void print_extended_on(outputStream* st) const;
1474
1475 virtual void print_gc_threads_on(outputStream* st) const;
1476 virtual void gc_threads_do(ThreadClosure* tc) const;
1477
1478 // Override
1479 void print_tracing_info() const;
1480
1481 // The following two methods are helpful for debugging RSet issues.
1482 void print_cset_rsets() PRODUCT_RETURN;
1483 void print_all_rsets() PRODUCT_RETURN;
1484
1485 // Convenience function to be used in situations where the heap type can be
1486 // asserted to be this type.
1487 static G1CollectedHeap* heap();
1488
1489 void set_region_short_lived_locked(HeapRegion* hr);
1490 // add appropriate methods for any other surv rate groups
1491
1492 YoungList* young_list() { return _young_list; }
1493
1494 // debugging
1495 bool check_young_list_well_formed() {
1496 return _young_list->check_list_well_formed();
1497 }
1498
1499 bool check_young_list_empty(bool check_heap,
1500 bool check_sample = true);
1501
1502 // *** Stuff related to concurrent marking. It's not clear to me that so
1503 // many of these need to be public.
1504
1505 // The functions below are helper functions that a subclass of
1506 // "CollectedHeap" can use in the implementation of its virtual
1507 // functions.
1508 // This performs a concurrent marking of the live objects in a
1509 // bitmap off to the side.
1510 void doConcurrentMark();
1511
1512 bool isMarkedPrev(oop obj) const;
1513 bool isMarkedNext(oop obj) const;
1514
1515 // vo == UsePrevMarking -> use "prev" marking information,
1516 // vo == UseNextMarking -> use "next" marking information,
1517 // vo == UseMarkWord -> use mark word from object header
1518 bool is_obj_dead_cond(const oop obj,
1519 const HeapRegion* hr,
1520 const VerifyOption vo) const {
1521
1522 switch (vo) {
1523 case VerifyOption_G1UsePrevMarking:
1524 return is_obj_dead(obj, hr);
1525 case VerifyOption_G1UseNextMarking:
1526 return is_obj_ill(obj, hr);
1527 default:
1528 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1529 return !obj->is_gc_marked();
1530 }
1531 }
1532
1533 // Determine if an object is dead, given the object and also
1534 // the region to which the object belongs. An object is dead
1535 // iff a) it was not allocated since the last mark and b) it
1536 // is not marked.
1537
1538 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1539 return
1540 !hr->obj_allocated_since_prev_marking(obj) &&
1541 !isMarkedPrev(obj);
1542 }
1543
1544 // This is used when copying an object to survivor space.
1545 // If the object is marked live, then we mark the copy live.
1546 // If the object is allocated since the start of this mark
1547 // cycle, then we mark the copy live.
1548 // If the object has been around since the previous mark
1549 // phase, and hasn't been marked yet during this phase,
1550 // then we don't mark it, we just wait for the
1551 // current marking cycle to get to it.
1552
1553 // This function returns true when an object has been
1554 // around since the previous marking and hasn't yet
1555 // been marked during this marking.
1556
1557 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1558 return
1559 !hr->obj_allocated_since_next_marking(obj) &&
1560 !isMarkedNext(obj);
1561 }
1562
1563 // Determine if an object is dead, given only the object itself.
1564 // This will find the region to which the object belongs and
1565 // then call the region version of the same function.
1566
1567 // Added if it is in permanent gen it isn't dead.
1568 // Added if it is NULL it isn't dead.
1569
1570 // vo == UsePrevMarking -> use "prev" marking information,
1571 // vo == UseNextMarking -> use "next" marking information,
1572 // vo == UseMarkWord -> use mark word from object header
1573 bool is_obj_dead_cond(const oop obj,
1574 const VerifyOption vo) const {
1575
1576 switch (vo) {
1577 case VerifyOption_G1UsePrevMarking:
1578 return is_obj_dead(obj);
1579 case VerifyOption_G1UseNextMarking:
1580 return is_obj_ill(obj);
1581 default:
1582 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1583 return !obj->is_gc_marked();
1584 }
1585 }
1586
1587 bool is_obj_dead(const oop obj) const {
1588 const HeapRegion* hr = heap_region_containing(obj);
1589 if (hr == NULL) {
1590 if (Universe::heap()->is_in_permanent(obj))
1591 return false;
1592 else if (obj == NULL) return false;
1593 else return true;
1594 }
1595 else return is_obj_dead(obj, hr);
1596 }
1597
1598 bool is_obj_ill(const oop obj) const {
1599 const HeapRegion* hr = heap_region_containing(obj);
1600 if (hr == NULL) {
1601 if (Universe::heap()->is_in_permanent(obj))
1602 return false;
1603 else if (obj == NULL) return false;
1604 else return true;
1605 }
1606 else return is_obj_ill(obj, hr);
1607 }
1608
1609 // The following is just to alert the verification code
1610 // that a full collection has occurred and that the
1611 // remembered sets are no longer up to date.
1612 bool _full_collection;
1613 void set_full_collection() { _full_collection = true;}
1614 void clear_full_collection() {_full_collection = false;}
1615 bool full_collection() {return _full_collection;}
1616
1617 ConcurrentMark* concurrent_mark() const { return _cm; }
1618 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1619
1620 // The dirty cards region list is used to record a subset of regions
1621 // whose cards need clearing. The list if populated during the
1622 // remembered set scanning and drained during the card table
1623 // cleanup. Although the methods are reentrant, population/draining
1624 // phases must not overlap. For synchronization purposes the last
1625 // element on the list points to itself.
1626 HeapRegion* _dirty_cards_region_list;
1627 void push_dirty_cards_region(HeapRegion* hr);
1628 HeapRegion* pop_dirty_cards_region();
1629
1630 public:
1631 void stop_conc_gc_threads();
1632
1633 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1634 void check_if_region_is_too_expensive(double predicted_time_ms);
1635 size_t pending_card_num();
1636 size_t max_pending_card_num();
1637 size_t cards_scanned();
1638
1639 protected:
1640 size_t _max_heap_capacity;
1641 };
1642
1643 #define use_local_bitmaps 1
1644 #define verify_local_bitmaps 0
1645 #define oop_buffer_length 256
1646
1647 #ifndef PRODUCT
1648 class GCLabBitMap;
1649 class GCLabBitMapClosure: public BitMapClosure {
1650 private:
1651 ConcurrentMark* _cm;
1652 GCLabBitMap* _bitmap;
1653
1654 public:
1655 GCLabBitMapClosure(ConcurrentMark* cm,
1656 GCLabBitMap* bitmap) {
1657 _cm = cm;
1658 _bitmap = bitmap;
1659 }
1660
1661 virtual bool do_bit(size_t offset);
1662 };
1663 #endif // !PRODUCT
1664
1665 class GCLabBitMap: public BitMap {
1666 private:
1667 ConcurrentMark* _cm;
1668
1669 int _shifter;
1670 size_t _bitmap_word_covers_words;
1671
1672 // beginning of the heap
1673 HeapWord* _heap_start;
1674
1675 // this is the actual start of the GCLab
1676 HeapWord* _real_start_word;
1677
1678 // this is the actual end of the GCLab
1679 HeapWord* _real_end_word;
1680
1681 // this is the first word, possibly located before the actual start
1682 // of the GCLab, that corresponds to the first bit of the bitmap
1683 HeapWord* _start_word;
1684
1685 // size of a GCLab in words
1686 size_t _gclab_word_size;
1687
1688 static int shifter() {
1689 return MinObjAlignment - 1;
1690 }
1691
1692 // how many heap words does a single bitmap word corresponds to?
1693 static size_t bitmap_word_covers_words() {
1694 return BitsPerWord << shifter();
1695 }
1696
1697 size_t gclab_word_size() const {
1698 return _gclab_word_size;
1699 }
1700
1701 // Calculates actual GCLab size in words
1702 size_t gclab_real_word_size() const {
1703 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1704 / BitsPerWord;
1705 }
1706
1707 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1708 size_t bits_in_bitmap = gclab_word_size >> shifter();
1709 // We are going to ensure that the beginning of a word in this
1710 // bitmap also corresponds to the beginning of a word in the
1711 // global marking bitmap. To handle the case where a GCLab
1712 // starts from the middle of the bitmap, we need to add enough
1713 // space (i.e. up to a bitmap word) to ensure that we have
1714 // enough bits in the bitmap.
1715 return bits_in_bitmap + BitsPerWord - 1;
1716 }
1717 public:
1718 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1719 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1720 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1721 _shifter(shifter()),
1722 _bitmap_word_covers_words(bitmap_word_covers_words()),
1723 _heap_start(heap_start),
1724 _gclab_word_size(gclab_word_size),
1725 _real_start_word(NULL),
1726 _real_end_word(NULL),
1727 _start_word(NULL)
1728 {
1729 guarantee( size_in_words() >= bitmap_size_in_words(),
1730 "just making sure");
1731 }
1732
1733 inline unsigned heapWordToOffset(HeapWord* addr) {
1734 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1735 assert(offset < size(), "offset should be within bounds");
1736 return offset;
1737 }
1738
1739 inline HeapWord* offsetToHeapWord(size_t offset) {
1740 HeapWord* addr = _start_word + (offset << _shifter);
1741 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1742 return addr;
1743 }
1744
1745 bool fields_well_formed() {
1746 bool ret1 = (_real_start_word == NULL) &&
1747 (_real_end_word == NULL) &&
1748 (_start_word == NULL);
1749 if (ret1)
1750 return true;
1751
1752 bool ret2 = _real_start_word >= _start_word &&
1753 _start_word < _real_end_word &&
1754 (_real_start_word + _gclab_word_size) == _real_end_word &&
1755 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1756 > _real_end_word;
1757 return ret2;
1758 }
1759
1760 inline bool mark(HeapWord* addr) {
1761 guarantee(use_local_bitmaps, "invariant");
1762 assert(fields_well_formed(), "invariant");
1763
1764 if (addr >= _real_start_word && addr < _real_end_word) {
1765 assert(!isMarked(addr), "should not have already been marked");
1766
1767 // first mark it on the bitmap
1768 at_put(heapWordToOffset(addr), true);
1769
1770 return true;
1771 } else {
1772 return false;
1773 }
1774 }
1775
1776 inline bool isMarked(HeapWord* addr) {
1777 guarantee(use_local_bitmaps, "invariant");
1778 assert(fields_well_formed(), "invariant");
1779
1780 return at(heapWordToOffset(addr));
1781 }
1782
1783 void set_buffer(HeapWord* start) {
1784 guarantee(use_local_bitmaps, "invariant");
1785 clear();
1786
1787 assert(start != NULL, "invariant");
1788 _real_start_word = start;
1789 _real_end_word = start + _gclab_word_size;
1790
1791 size_t diff =
1792 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1793 _start_word = start - diff;
1794
1795 assert(fields_well_formed(), "invariant");
1796 }
1797
1798 #ifndef PRODUCT
1799 void verify() {
1800 // verify that the marks have been propagated
1801 GCLabBitMapClosure cl(_cm, this);
1802 iterate(&cl);
1803 }
1804 #endif // PRODUCT
1805
1806 void retire() {
1807 guarantee(use_local_bitmaps, "invariant");
1808 assert(fields_well_formed(), "invariant");
1809
1810 if (_start_word != NULL) {
1811 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1812
1813 // this means that the bitmap was set up for the GCLab
1814 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1815
1816 mark_bitmap->mostly_disjoint_range_union(this,
1817 0, // always start from the start of the bitmap
1818 _start_word,
1819 gclab_real_word_size());
1820 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1821
1822 #ifndef PRODUCT
1823 if (use_local_bitmaps && verify_local_bitmaps)
1824 verify();
1825 #endif // PRODUCT
1826 } else {
1827 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1828 }
1829 }
1830
1831 size_t bitmap_size_in_words() const {
1832 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1833 }
1834
1835 };
1836
1837 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1838 private:
1839 bool _retired;
1840 bool _should_mark_objects;
1841 GCLabBitMap _bitmap;
1842
1843 public:
1844 G1ParGCAllocBuffer(size_t gclab_word_size);
1845
1846 inline bool mark(HeapWord* addr) {
1847 guarantee(use_local_bitmaps, "invariant");
1848 assert(_should_mark_objects, "invariant");
1849 return _bitmap.mark(addr);
1850 }
1851
1852 inline void set_buf(HeapWord* buf) {
1853 if (use_local_bitmaps && _should_mark_objects) {
1854 _bitmap.set_buffer(buf);
1855 }
1856 ParGCAllocBuffer::set_buf(buf);
1857 _retired = false;
1858 }
1859
1860 inline void retire(bool end_of_gc, bool retain) {
1861 if (_retired)
1862 return;
1863 if (use_local_bitmaps && _should_mark_objects) {
1864 _bitmap.retire();
1865 }
1866 ParGCAllocBuffer::retire(end_of_gc, retain);
1867 _retired = true;
1868 }
1869 };
1870
1871 class G1ParScanThreadState : public StackObj {
1872 protected:
1873 G1CollectedHeap* _g1h;
1874 RefToScanQueue* _refs;
1875 DirtyCardQueue _dcq;
1876 CardTableModRefBS* _ct_bs;
1877 G1RemSet* _g1_rem;
1878
1879 G1ParGCAllocBuffer _surviving_alloc_buffer;
1880 G1ParGCAllocBuffer _tenured_alloc_buffer;
1881 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1882 ageTable _age_table;
1883
1884 size_t _alloc_buffer_waste;
1885 size_t _undo_waste;
1886
1887 OopsInHeapRegionClosure* _evac_failure_cl;
1888 G1ParScanHeapEvacClosure* _evac_cl;
1889 G1ParScanPartialArrayClosure* _partial_scan_cl;
1890
1891 int _hash_seed;
1892 int _queue_num;
1893
1894 size_t _term_attempts;
1895
1896 double _start;
1897 double _start_strong_roots;
1898 double _strong_roots_time;
1899 double _start_term;
1900 double _term_time;
1901
1902 // Map from young-age-index (0 == not young, 1 is youngest) to
1903 // surviving words. base is what we get back from the malloc call
1904 size_t* _surviving_young_words_base;
1905 // this points into the array, as we use the first few entries for padding
1906 size_t* _surviving_young_words;
1907
1908 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1909
1910 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1911
1912 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1913
1914 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1915 CardTableModRefBS* ctbs() { return _ct_bs; }
1916
1917 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1918 if (!from->is_survivor()) {
1919 _g1_rem->par_write_ref(from, p, tid);
1920 }
1921 }
1922
1923 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1924 // If the new value of the field points to the same region or
1925 // is the to-space, we don't need to include it in the Rset updates.
1926 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1927 size_t card_index = ctbs()->index_for(p);
1928 // If the card hasn't been added to the buffer, do it.
1929 if (ctbs()->mark_card_deferred(card_index)) {
1930 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1931 }
1932 }
1933 }
1934
1935 public:
1936 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1937
1938 ~G1ParScanThreadState() {
1939 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1940 }
1941
1942 RefToScanQueue* refs() { return _refs; }
1943 ageTable* age_table() { return &_age_table; }
1944
1945 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1946 return _alloc_buffers[purpose];
1947 }
1948
1949 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1950 size_t undo_waste() const { return _undo_waste; }
1951
1952 #ifdef ASSERT
1953 bool verify_ref(narrowOop* ref) const;
1954 bool verify_ref(oop* ref) const;
1955 bool verify_task(StarTask ref) const;
1956 #endif // ASSERT
1957
1958 template <class T> void push_on_queue(T* ref) {
1959 assert(verify_ref(ref), "sanity");
1960 refs()->push(ref);
1961 }
1962
1963 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1964 if (G1DeferredRSUpdate) {
1965 deferred_rs_update(from, p, tid);
1966 } else {
1967 immediate_rs_update(from, p, tid);
1968 }
1969 }
1970
1971 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1972
1973 HeapWord* obj = NULL;
1974 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1975 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1976 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1977 assert(gclab_word_size == alloc_buf->word_sz(),
1978 "dynamic resizing is not supported");
1979 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1980 alloc_buf->retire(false, false);
1981
1982 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1983 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1984 // Otherwise.
1985 alloc_buf->set_buf(buf);
1986
1987 obj = alloc_buf->allocate(word_sz);
1988 assert(obj != NULL, "buffer was definitely big enough...");
1989 } else {
1990 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1991 }
1992 return obj;
1993 }
1994
1995 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1996 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1997 if (obj != NULL) return obj;
1998 return allocate_slow(purpose, word_sz);
1999 }
2000
2001 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
2002 if (alloc_buffer(purpose)->contains(obj)) {
2003 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2004 "should contain whole object");
2005 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2006 } else {
2007 CollectedHeap::fill_with_object(obj, word_sz);
2008 add_to_undo_waste(word_sz);
2009 }
2010 }
2011
2012 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2013 _evac_failure_cl = evac_failure_cl;
2014 }
2015 OopsInHeapRegionClosure* evac_failure_closure() {
2016 return _evac_failure_cl;
2017 }
2018
2019 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2020 _evac_cl = evac_cl;
2021 }
2022
2023 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2024 _partial_scan_cl = partial_scan_cl;
2025 }
2026
2027 int* hash_seed() { return &_hash_seed; }
2028 int queue_num() { return _queue_num; }
2029
2030 size_t term_attempts() const { return _term_attempts; }
2031 void note_term_attempt() { _term_attempts++; }
2032
2033 void start_strong_roots() {
2034 _start_strong_roots = os::elapsedTime();
2035 }
2036 void end_strong_roots() {
2037 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2038 }
2039 double strong_roots_time() const { return _strong_roots_time; }
2040
2041 void start_term_time() {
2042 note_term_attempt();
2043 _start_term = os::elapsedTime();
2044 }
2045 void end_term_time() {
2046 _term_time += (os::elapsedTime() - _start_term);
2047 }
2048 double term_time() const { return _term_time; }
2049
2050 double elapsed_time() const {
2051 return os::elapsedTime() - _start;
2052 }
2053
2054 static void
2055 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2056 void
2057 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2058
2059 size_t* surviving_young_words() {
2060 // We add on to hide entry 0 which accumulates surviving words for
2061 // age -1 regions (i.e. non-young ones)
2062 return _surviving_young_words;
2063 }
2064
2065 void retire_alloc_buffers() {
2066 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2067 size_t waste = _alloc_buffers[ap]->words_remaining();
2068 add_to_alloc_buffer_waste(waste);
2069 _alloc_buffers[ap]->retire(true, false);
2070 }
2071 }
2072
2073 template <class T> void deal_with_reference(T* ref_to_scan) {
2074 if (has_partial_array_mask(ref_to_scan)) {
2075 _partial_scan_cl->do_oop_nv(ref_to_scan);
2076 } else {
2077 // Note: we can use "raw" versions of "region_containing" because
2078 // "obj_to_scan" is definitely in the heap, and is not in a
2079 // humongous region.
2080 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2081 _evac_cl->set_region(r);
2082 _evac_cl->do_oop_nv(ref_to_scan);
2083 }
2084 }
2085
2086 void deal_with_reference(StarTask ref) {
2087 assert(verify_task(ref), "sanity");
2088 if (ref.is_narrow()) {
2089 deal_with_reference((narrowOop*)ref);
2090 } else {
2091 deal_with_reference((oop*)ref);
2092 }
2093 }
2094
2095 public:
2096 void trim_queue();
2097 };
2098
2099 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP