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 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 humongous regions.
243 MasterHumongousRegionSet _humongous_set;
244
245 // The number of regions we could create by expansion.
246 size_t _expansion_regions;
247
248 // The block offset table for the G1 heap.
249 G1BlockOffsetSharedArray* _bot_shared;
250
251 // Move all of the regions off the free lists, then rebuild those free
252 // lists, before and after full GC.
253 void tear_down_region_lists();
254 void rebuild_region_lists();
255
256 // The sequence of all heap regions in the heap.
257 HeapRegionSeq _hrs;
258
259 // Alloc region used to satisfy mutator allocation requests.
260 MutatorAllocRegion _mutator_alloc_region;
261
262 // Alloc region used to satisfy allocation requests by the GC for
263 // survivor objects.
264 SurvivorGCAllocRegion _survivor_gc_alloc_region;
265
266 // Alloc region used to satisfy allocation requests by the GC for
267 // old objects.
268 OldGCAllocRegion _old_gc_alloc_region;
269
270 // The last old region we allocated to during the last GC.
271 // Typically, it is not full so we should re-use it during the next GC.
272 HeapRegion* _retained_old_gc_alloc_region;
273
274 // It resets the mutator alloc region before new allocations can take place.
275 void init_mutator_alloc_region();
276
277 // It releases the mutator alloc region.
278 void release_mutator_alloc_region();
279
280 // It initializes the GC alloc regions at the start of a GC.
281 void init_gc_alloc_regions();
282
283 // It releases the GC alloc regions at the end of a GC.
284 void release_gc_alloc_regions();
285
286 // It does any cleanup that needs to be done on the GC alloc regions
287 // before a Full GC.
288 void abandon_gc_alloc_regions();
289
290 // Helper for monitoring and management support.
291 G1MonitoringSupport* _g1mm;
292
293 // Determines PLAB size for a particular allocation purpose.
294 static size_t desired_plab_sz(GCAllocPurpose purpose);
295
296 // Outside of GC pauses, the number of bytes used in all regions other
297 // than the current allocation region.
298 size_t _summary_bytes_used;
299
300 // This is used for a quick test on whether a reference points into
301 // the collection set or not. Basically, we have an array, with one
302 // byte per region, and that byte denotes whether the corresponding
303 // region is in the collection set or not. The entry corresponding
304 // the bottom of the heap, i.e., region 0, is pointed to by
305 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
306 // biased so that it actually points to address 0 of the address
307 // space, to make the test as fast as possible (we can simply shift
308 // the address to address into it, instead of having to subtract the
309 // bottom of the heap from the address before shifting it; basically
310 // it works in the same way the card table works).
311 bool* _in_cset_fast_test;
312
313 // The allocated array used for the fast test on whether a reference
314 // points into the collection set or not. This field is also used to
315 // free the array.
316 bool* _in_cset_fast_test_base;
317
318 // The length of the _in_cset_fast_test_base array.
319 size_t _in_cset_fast_test_length;
320
321 volatile unsigned _gc_time_stamp;
322
323 size_t* _surviving_young_words;
324
325 G1HRPrinter _hr_printer;
326
327 void setup_surviving_young_words();
328 void update_surviving_young_words(size_t* surv_young_words);
329 void cleanup_surviving_young_words();
330
331 // It decides whether an explicit GC should start a concurrent cycle
332 // instead of doing a STW GC. Currently, a concurrent cycle is
333 // explicitly started if:
334 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
335 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
336 bool should_do_concurrent_full_gc(GCCause::Cause cause);
337
338 // Keeps track of how many "full collections" (i.e., Full GCs or
339 // concurrent cycles) we have completed. The number of them we have
340 // started is maintained in _total_full_collections in CollectedHeap.
341 volatile unsigned int _full_collections_completed;
342
343 // This is a non-product method that is helpful for testing. It is
344 // called at the end of a GC and artificially expands the heap by
345 // allocating a number of dead regions. This way we can induce very
346 // frequent marking cycles and stress the cleanup / concurrent
347 // cleanup code more (as all the regions that will be allocated by
348 // this method will be found dead by the marking cycle).
349 void allocate_dummy_regions() PRODUCT_RETURN;
350
351 // These are macros so that, if the assert fires, we get the correct
352 // line number, file, etc.
353
354 #define heap_locking_asserts_err_msg(_extra_message_) \
355 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
356 (_extra_message_), \
357 BOOL_TO_STR(Heap_lock->owned_by_self()), \
358 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
359 BOOL_TO_STR(Thread::current()->is_VM_thread()))
360
361 #define assert_heap_locked() \
362 do { \
363 assert(Heap_lock->owned_by_self(), \
364 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
365 } while (0)
366
367 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
368 do { \
369 assert(Heap_lock->owned_by_self() || \
370 (SafepointSynchronize::is_at_safepoint() && \
371 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
372 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
373 "should be at a safepoint")); \
374 } while (0)
375
376 #define assert_heap_locked_and_not_at_safepoint() \
377 do { \
378 assert(Heap_lock->owned_by_self() && \
379 !SafepointSynchronize::is_at_safepoint(), \
380 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
381 "should not be at a safepoint")); \
382 } while (0)
383
384 #define assert_heap_not_locked() \
385 do { \
386 assert(!Heap_lock->owned_by_self(), \
387 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
388 } while (0)
389
390 #define assert_heap_not_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 not be holding the Heap_lock and " \
395 "should not be at a safepoint")); \
396 } while (0)
397
398 #define assert_at_safepoint(_should_be_vm_thread_) \
399 do { \
400 assert(SafepointSynchronize::is_at_safepoint() && \
401 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
402 heap_locking_asserts_err_msg("should be at a safepoint")); \
403 } while (0)
404
405 #define assert_not_at_safepoint() \
406 do { \
407 assert(!SafepointSynchronize::is_at_safepoint(), \
408 heap_locking_asserts_err_msg("should not be at a safepoint")); \
409 } while (0)
410
411 protected:
412
413 // The young region list.
414 YoungList* _young_list;
415
416 // The current policy object for the collector.
417 G1CollectorPolicy* _g1_policy;
418
419 // This is the second level of trying to allocate a new region. If
420 // new_region() didn't find a region on the free_list, this call will
421 // check whether there's anything available on the
422 // secondary_free_list and/or wait for more regions to appear on
423 // that list, if _free_regions_coming is set.
424 HeapRegion* new_region_try_secondary_free_list();
425
426 // Try to allocate a single non-humongous HeapRegion sufficient for
427 // an allocation of the given word_size. If do_expand is true,
428 // attempt to expand the heap if necessary to satisfy the allocation
429 // request.
430 HeapRegion* new_region(size_t word_size, bool do_expand);
431
432 // Attempt to satisfy a humongous allocation request of the given
433 // size by finding a contiguous set of free regions of num_regions
434 // length and remove them from the master free list. Return the
435 // index of the first region or G1_NULL_HRS_INDEX if the search
436 // was unsuccessful.
437 size_t humongous_obj_allocate_find_first(size_t num_regions,
438 size_t word_size);
439
440 // Initialize a contiguous set of free regions of length num_regions
441 // and starting at index first so that they appear as a single
442 // humongous region.
443 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
444 size_t num_regions,
445 size_t word_size);
446
447 // Attempt to allocate a humongous object of the given size. Return
448 // NULL if unsuccessful.
449 HeapWord* humongous_obj_allocate(size_t word_size);
450
451 // The following two methods, allocate_new_tlab() and
452 // mem_allocate(), are the two main entry points from the runtime
453 // into the G1's allocation routines. They have the following
454 // assumptions:
455 //
456 // * They should both be called outside safepoints.
457 //
458 // * They should both be called without holding the Heap_lock.
459 //
460 // * All allocation requests for new TLABs should go to
461 // allocate_new_tlab().
462 //
463 // * All non-TLAB allocation requests should go to mem_allocate().
464 //
465 // * If either call cannot satisfy the allocation request using the
466 // current allocating region, they will try to get a new one. If
467 // this fails, they will attempt to do an evacuation pause and
468 // retry the allocation.
469 //
470 // * If all allocation attempts fail, even after trying to schedule
471 // an evacuation pause, allocate_new_tlab() will return NULL,
472 // whereas mem_allocate() will attempt a heap expansion and/or
473 // schedule a Full GC.
474 //
475 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
476 // should never be called with word_size being humongous. All
477 // humongous allocation requests should go to mem_allocate() which
478 // will satisfy them with a special path.
479
480 virtual HeapWord* allocate_new_tlab(size_t word_size);
481
482 virtual HeapWord* mem_allocate(size_t word_size,
483 bool* gc_overhead_limit_was_exceeded);
484
485 // The following three methods take a gc_count_before_ret
486 // parameter which is used to return the GC count if the method
487 // returns NULL. Given that we are required to read the GC count
488 // while holding the Heap_lock, and these paths will take the
489 // Heap_lock at some point, it's easier to get them to read the GC
490 // count while holding the Heap_lock before they return NULL instead
491 // of the caller (namely: mem_allocate()) having to also take the
492 // Heap_lock just to read the GC count.
493
494 // First-level mutator allocation attempt: try to allocate out of
495 // the mutator alloc region without taking the Heap_lock. This
496 // should only be used for non-humongous allocations.
497 inline HeapWord* attempt_allocation(size_t word_size,
498 unsigned int* gc_count_before_ret);
499
500 // Second-level mutator allocation attempt: take the Heap_lock and
501 // retry the allocation attempt, potentially scheduling a GC
502 // pause. This should only be used for non-humongous allocations.
503 HeapWord* attempt_allocation_slow(size_t word_size,
504 unsigned int* gc_count_before_ret);
505
506 // Takes the Heap_lock and attempts a humongous allocation. It can
507 // potentially schedule a GC pause.
508 HeapWord* attempt_allocation_humongous(size_t word_size,
509 unsigned int* gc_count_before_ret);
510
511 // Allocation attempt that should be called during safepoints (e.g.,
512 // at the end of a successful GC). expect_null_mutator_alloc_region
513 // specifies whether the mutator alloc region is expected to be NULL
514 // or not.
515 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
516 bool expect_null_mutator_alloc_region);
517
518 // It dirties the cards that cover the block so that so that the post
519 // write barrier never queues anything when updating objects on this
520 // block. It is assumed (and in fact we assert) that the block
521 // belongs to a young region.
522 inline void dirty_young_block(HeapWord* start, size_t word_size);
523
524 // Allocate blocks during garbage collection. Will ensure an
525 // allocation region, either by picking one or expanding the
526 // heap, and then allocate a block of the given size. The block
527 // may not be a humongous - it must fit into a single heap region.
528 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
529
530 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
531 HeapRegion* alloc_region,
532 bool par,
533 size_t word_size);
534
535 // Ensure that no further allocations can happen in "r", bearing in mind
536 // that parallel threads might be attempting allocations.
537 void par_allocate_remaining_space(HeapRegion* r);
538
539 // Allocation attempt during GC for a survivor object / PLAB.
540 inline HeapWord* survivor_attempt_allocation(size_t word_size);
541
542 // Allocation attempt during GC for an old object / PLAB.
543 inline HeapWord* old_attempt_allocation(size_t word_size);
544
545 // These methods are the "callbacks" from the G1AllocRegion class.
546
547 // For mutator alloc regions.
548 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
549 void retire_mutator_alloc_region(HeapRegion* alloc_region,
550 size_t allocated_bytes);
551
552 // For GC alloc regions.
553 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
554 GCAllocPurpose ap);
555 void retire_gc_alloc_region(HeapRegion* alloc_region,
556 size_t allocated_bytes, GCAllocPurpose ap);
557
558 // - if explicit_gc is true, the GC is for a System.gc() or a heap
559 // inspection request and should collect the entire heap
560 // - if clear_all_soft_refs is true, all soft references should be
561 // cleared during the GC
562 // - if explicit_gc is false, word_size describes the allocation that
563 // the GC should attempt (at least) to satisfy
564 // - it returns false if it is unable to do the collection due to the
565 // GC locker being active, true otherwise
566 bool do_collection(bool explicit_gc,
567 bool clear_all_soft_refs,
568 size_t word_size);
569
570 // Callback from VM_G1CollectFull operation.
571 // Perform a full collection.
572 void do_full_collection(bool clear_all_soft_refs);
573
574 // Resize the heap if necessary after a full collection. If this is
575 // after a collect-for allocation, "word_size" is the allocation size,
576 // and will be considered part of the used portion of the heap.
577 void resize_if_necessary_after_full_collection(size_t word_size);
578
579 // Callback from VM_G1CollectForAllocation operation.
580 // This function does everything necessary/possible to satisfy a
581 // failed allocation request (including collection, expansion, etc.)
582 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
583
584 // Attempting to expand the heap sufficiently
585 // to support an allocation of the given "word_size". If
586 // successful, perform the allocation and return the address of the
587 // allocated block, or else "NULL".
588 HeapWord* expand_and_allocate(size_t word_size);
589
590 // Process any reference objects discovered during
591 // an incremental evacuation pause.
592 void process_discovered_references();
593
594 // Enqueue any remaining discovered references
595 // after processing.
596 void enqueue_discovered_references();
597
598 public:
599
600 G1MonitoringSupport* g1mm() { return _g1mm; }
601
602 // Expand the garbage-first heap by at least the given size (in bytes!).
603 // Returns true if the heap was expanded by the requested amount;
604 // false otherwise.
605 // (Rounds up to a HeapRegion boundary.)
606 bool expand(size_t expand_bytes);
607
608 // Do anything common to GC's.
609 virtual void gc_prologue(bool full);
610 virtual void gc_epilogue(bool full);
611
612 // We register a region with the fast "in collection set" test. We
613 // simply set to true the array slot corresponding to this region.
614 void register_region_with_in_cset_fast_test(HeapRegion* r) {
615 assert(_in_cset_fast_test_base != NULL, "sanity");
616 assert(r->in_collection_set(), "invariant");
617 size_t index = r->hrs_index();
618 assert(index < _in_cset_fast_test_length, "invariant");
619 assert(!_in_cset_fast_test_base[index], "invariant");
620 _in_cset_fast_test_base[index] = true;
621 }
622
623 // This is a fast test on whether a reference points into the
624 // collection set or not. It does not assume that the reference
625 // points into the heap; if it doesn't, it will return false.
626 bool in_cset_fast_test(oop obj) {
627 assert(_in_cset_fast_test != NULL, "sanity");
628 if (_g1_committed.contains((HeapWord*) obj)) {
629 // no need to subtract the bottom of the heap from obj,
630 // _in_cset_fast_test is biased
631 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
632 bool ret = _in_cset_fast_test[index];
633 // let's make sure the result is consistent with what the slower
634 // test returns
635 assert( ret || !obj_in_cs(obj), "sanity");
636 assert(!ret || obj_in_cs(obj), "sanity");
637 return ret;
638 } else {
639 return false;
640 }
641 }
642
643 void clear_cset_fast_test() {
644 assert(_in_cset_fast_test_base != NULL, "sanity");
645 memset(_in_cset_fast_test_base, false,
646 _in_cset_fast_test_length * sizeof(bool));
647 }
648
649 // This is called at the end of either a concurrent cycle or a Full
650 // GC to update the number of full collections completed. Those two
651 // can happen in a nested fashion, i.e., we start a concurrent
652 // cycle, a Full GC happens half-way through it which ends first,
653 // and then the cycle notices that a Full GC happened and ends
654 // too. The concurrent parameter is a boolean to help us do a bit
655 // tighter consistency checking in the method. If concurrent is
656 // false, the caller is the inner caller in the nesting (i.e., the
657 // Full GC). If concurrent is true, the caller is the outer caller
658 // in this nesting (i.e., the concurrent cycle). Further nesting is
659 // not currently supported. The end of the this call also notifies
660 // the FullGCCount_lock in case a Java thread is waiting for a full
661 // GC to happen (e.g., it called System.gc() with
662 // +ExplicitGCInvokesConcurrent).
663 void increment_full_collections_completed(bool concurrent);
664
665 unsigned int full_collections_completed() {
666 return _full_collections_completed;
667 }
668
669 G1HRPrinter* hr_printer() { return &_hr_printer; }
670
671 protected:
672
673 // Shrink the garbage-first heap by at most the given size (in bytes!).
674 // (Rounds down to a HeapRegion boundary.)
675 virtual void shrink(size_t expand_bytes);
676 void shrink_helper(size_t expand_bytes);
677
678 #if TASKQUEUE_STATS
679 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
680 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
681 void reset_taskqueue_stats();
682 #endif // TASKQUEUE_STATS
683
684 // Schedule the VM operation that will do an evacuation pause to
685 // satisfy an allocation request of word_size. *succeeded will
686 // return whether the VM operation was successful (it did do an
687 // evacuation pause) or not (another thread beat us to it or the GC
688 // locker was active). Given that we should not be holding the
689 // Heap_lock when we enter this method, we will pass the
690 // gc_count_before (i.e., total_collections()) as a parameter since
691 // it has to be read while holding the Heap_lock. Currently, both
692 // methods that call do_collection_pause() release the Heap_lock
693 // before the call, so it's easy to read gc_count_before just before.
694 HeapWord* do_collection_pause(size_t word_size,
695 unsigned int gc_count_before,
696 bool* succeeded);
697
698 // The guts of the incremental collection pause, executed by the vm
699 // thread. It returns false if it is unable to do the collection due
700 // to the GC locker being active, true otherwise
701 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
702
703 // Actually do the work of evacuating the collection set.
704 void evacuate_collection_set();
705
706 // The g1 remembered set of the heap.
707 G1RemSet* _g1_rem_set;
708 // And it's mod ref barrier set, used to track updates for the above.
709 ModRefBarrierSet* _mr_bs;
710
711 // A set of cards that cover the objects for which the Rsets should be updated
712 // concurrently after the collection.
713 DirtyCardQueueSet _dirty_card_queue_set;
714
715 // The Heap Region Rem Set Iterator.
716 HeapRegionRemSetIterator** _rem_set_iterator;
717
718 // The closure used to refine a single card.
719 RefineCardTableEntryClosure* _refine_cte_cl;
720
721 // A function to check the consistency of dirty card logs.
722 void check_ct_logs_at_safepoint();
723
724 // A DirtyCardQueueSet that is used to hold cards that contain
725 // references into the current collection set. This is used to
726 // update the remembered sets of the regions in the collection
727 // set in the event of an evacuation failure.
728 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
729
730 // After a collection pause, make the regions in the CS into free
731 // regions.
732 void free_collection_set(HeapRegion* cs_head);
733
734 // Abandon the current collection set without recording policy
735 // statistics or updating free lists.
736 void abandon_collection_set(HeapRegion* cs_head);
737
738 // Applies "scan_non_heap_roots" to roots outside the heap,
739 // "scan_rs" to roots inside the heap (having done "set_region" to
740 // indicate the region in which the root resides), and does "scan_perm"
741 // (setting the generation to the perm generation.) If "scan_rs" is
742 // NULL, then this step is skipped. The "worker_i"
743 // param is for use with parallel roots processing, and should be
744 // the "i" of the calling parallel worker thread's work(i) function.
745 // In the sequential case this param will be ignored.
746 void g1_process_strong_roots(bool collecting_perm_gen,
747 SharedHeap::ScanningOption so,
748 OopClosure* scan_non_heap_roots,
749 OopsInHeapRegionClosure* scan_rs,
750 OopsInGenClosure* scan_perm,
751 int worker_i);
752
753 // Apply "blk" to all the weak roots of the system. These include
754 // JNI weak roots, the code cache, system dictionary, symbol table,
755 // string table, and referents of reachable weak refs.
756 void g1_process_weak_roots(OopClosure* root_closure,
757 OopClosure* non_root_closure);
758
759 // Frees a non-humongous region by initializing its contents and
760 // adding it to the free list that's passed as a parameter (this is
761 // usually a local list which will be appended to the master free
762 // list later). The used bytes of freed regions are accumulated in
763 // pre_used. If par is true, the region's RSet will not be freed
764 // up. The assumption is that this will be done later.
765 void free_region(HeapRegion* hr,
766 size_t* pre_used,
767 FreeRegionList* free_list,
768 bool par);
769
770 // Frees a humongous region by collapsing it into individual regions
771 // and calling free_region() for each of them. The freed regions
772 // will be added to the free list that's passed as a parameter (this
773 // is usually a local list which will be appended to the master free
774 // list later). The used bytes of freed regions are accumulated in
775 // pre_used. If par is true, the region's RSet will not be freed
776 // up. The assumption is that this will be done later.
777 void free_humongous_region(HeapRegion* hr,
778 size_t* pre_used,
779 FreeRegionList* free_list,
780 HumongousRegionSet* humongous_proxy_set,
781 bool par);
782
783 // Notifies all the necessary spaces that the committed space has
784 // been updated (either expanded or shrunk). It should be called
785 // after _g1_storage is updated.
786 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
787
788 // The concurrent marker (and the thread it runs in.)
789 ConcurrentMark* _cm;
790 ConcurrentMarkThread* _cmThread;
791 bool _mark_in_progress;
792
793 // The concurrent refiner.
794 ConcurrentG1Refine* _cg1r;
795
796 // The parallel task queues
797 RefToScanQueueSet *_task_queues;
798
799 // True iff a evacuation has failed in the current collection.
800 bool _evacuation_failed;
801
802 // Set the attribute indicating whether evacuation has failed in the
803 // current collection.
804 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
805
806 // Failed evacuations cause some logical from-space objects to have
807 // forwarding pointers to themselves. Reset them.
808 void remove_self_forwarding_pointers();
809
810 // When one is non-null, so is the other. Together, they each pair is
811 // an object with a preserved mark, and its mark value.
812 GrowableArray<oop>* _objs_with_preserved_marks;
813 GrowableArray<markOop>* _preserved_marks_of_objs;
814
815 // Preserve the mark of "obj", if necessary, in preparation for its mark
816 // word being overwritten with a self-forwarding-pointer.
817 void preserve_mark_if_necessary(oop obj, markOop m);
818
819 // The stack of evac-failure objects left to be scanned.
820 GrowableArray<oop>* _evac_failure_scan_stack;
821 // The closure to apply to evac-failure objects.
822
823 OopsInHeapRegionClosure* _evac_failure_closure;
824 // Set the field above.
825 void
826 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
827 _evac_failure_closure = evac_failure_closure;
828 }
829
830 // Push "obj" on the scan stack.
831 void push_on_evac_failure_scan_stack(oop obj);
832 // Process scan stack entries until the stack is empty.
833 void drain_evac_failure_scan_stack();
834 // True iff an invocation of "drain_scan_stack" is in progress; to
835 // prevent unnecessary recursion.
836 bool _drain_in_progress;
837
838 // Do any necessary initialization for evacuation-failure handling.
839 // "cl" is the closure that will be used to process evac-failure
840 // objects.
841 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
842 // Do any necessary cleanup for evacuation-failure handling data
843 // structures.
844 void finalize_for_evac_failure();
845
846 // An attempt to evacuate "obj" has failed; take necessary steps.
847 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
848 void handle_evacuation_failure_common(oop obj, markOop m);
849
850 // ("Weak") Reference processing support.
851 //
852 // G1 has 2 instances of the referece processor class. One
853 // (_ref_processor_cm) handles reference object discovery
854 // and subsequent processing during concurrent marking cycles.
855 //
856 // The other (_ref_processor_stw) handles reference object
857 // discovery and processing during full GCs and incremental
858 // evacuation pauses.
859 //
860 // During an incremental pause, reference discovery will be
861 // temporarily disabled for _ref_processor_cm and will be
862 // enabled for _ref_processor_stw. At the end of the evacuation
863 // pause references discovered by _ref_processor_stw will be
864 // processed and discovery will be disabled. The previous
865 // setting for reference object discovery for _ref_processor_cm
866 // will be re-instated.
867 //
868 // At the start of marking:
869 // * Discovery by the CM ref processor is verified to be inactive
870 // and it's discovered lists are empty.
871 // * Discovery by the CM ref processor is then enabled.
872 //
873 // At the end of marking:
874 // * Any references on the CM ref processor's discovered
875 // lists are processed (possibly MT).
876 //
877 // At the start of full GC we:
878 // * Disable discovery by the CM ref processor and
879 // empty CM ref processor's discovered lists
880 // (without processing any entries).
881 // * Verify that the STW ref processor is inactive and it's
882 // discovered lists are empty.
883 // * Temporarily set STW ref processor discovery as single threaded.
884 // * Temporarily clear the STW ref processor's _is_alive_non_header
885 // field.
886 // * Finally enable discovery by the STW ref processor.
887 //
888 // The STW ref processor is used to record any discovered
889 // references during the full GC.
890 //
891 // At the end of a full GC we:
892 // * Will enqueue any non-live discovered references on the
893 // STW ref processor's discovered lists. This makes the
894 // STW ref processor inactive by disabling discovery.
895 // * Verify that the CM ref processor is still inactive
896 // and no references have been placed on it's discovered
897 // lists (also checked as a precondition during initial marking).
898
899 // The (stw) reference processor...
900 ReferenceProcessor* _ref_processor_stw;
901
902 // Instance of the is_alive closure for embedding into the
903 // STW reference processor as the _is_alive_non_header field.
904 // The _is_alive_non_header prevents unnecessary additions to
905 // the discovered lists during reference discovery.
906 G1STWIsAliveClosure _is_alive_closure_stw;
907
908 // The (concurrent marking) reference processor...
909 ReferenceProcessor* _ref_processor_cm;
910
911 // Instance of the concurrent mark is_alive closure for embedding
912 // into the Concurrent Marking reference processor as the
913 // _is_alive_non_header field. The _is_alive_non_header
914 // prevents unnecessary additions to the discovered lists
915 // during concurrent discovery.
916 G1CMIsAliveClosure _is_alive_closure_cm;
917
918 enum G1H_process_strong_roots_tasks {
919 G1H_PS_mark_stack_oops_do,
920 G1H_PS_refProcessor_oops_do,
921 // Leave this one last.
922 G1H_PS_NumElements
923 };
924
925 SubTasksDone* _process_strong_tasks;
926
927 volatile bool _free_regions_coming;
928
929 public:
930
931 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
932
933 void set_refine_cte_cl_concurrency(bool concurrent);
934
935 RefToScanQueue *task_queue(int i) const;
936
937 // A set of cards where updates happened during the GC
938 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
939
940 // A DirtyCardQueueSet that is used to hold cards that contain
941 // references into the current collection set. This is used to
942 // update the remembered sets of the regions in the collection
943 // set in the event of an evacuation failure.
944 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
945 { return _into_cset_dirty_card_queue_set; }
946
947 // Create a G1CollectedHeap with the specified policy.
948 // Must call the initialize method afterwards.
949 // May not return if something goes wrong.
950 G1CollectedHeap(G1CollectorPolicy* policy);
951
952 // Initialize the G1CollectedHeap to have the initial and
953 // maximum sizes, permanent generation, and remembered and barrier sets
954 // specified by the policy object.
955 jint initialize();
956
957 // Initialize weak reference processing.
958 virtual void ref_processing_init();
959
960 void set_par_threads(int t) {
961 SharedHeap::set_par_threads(t);
962 _process_strong_tasks->set_n_threads(t);
963 }
964
965 virtual CollectedHeap::Name kind() const {
966 return CollectedHeap::G1CollectedHeap;
967 }
968
969 // The current policy object for the collector.
970 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
971
972 // Adaptive size policy. No such thing for g1.
973 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
974
975 // The rem set and barrier set.
976 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
977 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
978
979 // The rem set iterator.
980 HeapRegionRemSetIterator* rem_set_iterator(int i) {
981 return _rem_set_iterator[i];
982 }
983
984 HeapRegionRemSetIterator* rem_set_iterator() {
985 return _rem_set_iterator[0];
986 }
987
988 unsigned get_gc_time_stamp() {
989 return _gc_time_stamp;
990 }
991
992 void reset_gc_time_stamp() {
993 _gc_time_stamp = 0;
994 OrderAccess::fence();
995 }
996
997 void increment_gc_time_stamp() {
998 ++_gc_time_stamp;
999 OrderAccess::fence();
1000 }
1001
1002 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1003 DirtyCardQueue* into_cset_dcq,
1004 bool concurrent, int worker_i);
1005
1006 // The shared block offset table array.
1007 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1008
1009 // Reference Processing accessors
1010
1011 // The STW reference processor....
1012 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1013
1014 // The Concurent Marking reference processor...
1015 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1016
1017 virtual size_t capacity() const;
1018 virtual size_t used() const;
1019 // This should be called when we're not holding the heap lock. The
1020 // result might be a bit inaccurate.
1021 size_t used_unlocked() const;
1022 size_t recalculate_used() const;
1023
1024 // These virtual functions do the actual allocation.
1025 // Some heaps may offer a contiguous region for shared non-blocking
1026 // allocation, via inlined code (by exporting the address of the top and
1027 // end fields defining the extent of the contiguous allocation region.)
1028 // But G1CollectedHeap doesn't yet support this.
1029
1030 // Return an estimate of the maximum allocation that could be performed
1031 // without triggering any collection or expansion activity. In a
1032 // generational collector, for example, this is probably the largest
1033 // allocation that could be supported (without expansion) in the youngest
1034 // generation. It is "unsafe" because no locks are taken; the result
1035 // should be treated as an approximation, not a guarantee, for use in
1036 // heuristic resizing decisions.
1037 virtual size_t unsafe_max_alloc();
1038
1039 virtual bool is_maximal_no_gc() const {
1040 return _g1_storage.uncommitted_size() == 0;
1041 }
1042
1043 // The total number of regions in the heap.
1044 size_t n_regions() { return _hrs.length(); }
1045
1046 // The max number of regions in the heap.
1047 size_t max_regions() { return _hrs.max_length(); }
1048
1049 // The number of regions that are completely free.
1050 size_t free_regions() { return _free_list.length(); }
1051
1052 // The number of regions that are not completely free.
1053 size_t used_regions() { return n_regions() - free_regions(); }
1054
1055 // The number of regions available for "regular" expansion.
1056 size_t expansion_regions() { return _expansion_regions; }
1057
1058 // Factory method for HeapRegion instances. It will return NULL if
1059 // the allocation fails.
1060 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1061
1062 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1063 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1064 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1065 void verify_dirty_young_regions() PRODUCT_RETURN;
1066
1067 // verify_region_sets() performs verification over the region
1068 // lists. It will be compiled in the product code to be used when
1069 // necessary (i.e., during heap verification).
1070 void verify_region_sets();
1071
1072 // verify_region_sets_optional() is planted in the code for
1073 // list verification in non-product builds (and it can be enabled in
1074 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1075 #if HEAP_REGION_SET_FORCE_VERIFY
1076 void verify_region_sets_optional() {
1077 verify_region_sets();
1078 }
1079 #else // HEAP_REGION_SET_FORCE_VERIFY
1080 void verify_region_sets_optional() { }
1081 #endif // HEAP_REGION_SET_FORCE_VERIFY
1082
1083 #ifdef ASSERT
1084 bool is_on_master_free_list(HeapRegion* hr) {
1085 return hr->containing_set() == &_free_list;
1086 }
1087
1088 bool is_in_humongous_set(HeapRegion* hr) {
1089 return hr->containing_set() == &_humongous_set;
1090 }
1091 #endif // ASSERT
1092
1093 // Wrapper for the region list operations that can be called from
1094 // methods outside this class.
1095
1096 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1097 _secondary_free_list.add_as_tail(list);
1098 }
1099
1100 void append_secondary_free_list() {
1101 _free_list.add_as_head(&_secondary_free_list);
1102 }
1103
1104 void append_secondary_free_list_if_not_empty_with_lock() {
1105 // If the secondary free list looks empty there's no reason to
1106 // take the lock and then try to append it.
1107 if (!_secondary_free_list.is_empty()) {
1108 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1109 append_secondary_free_list();
1110 }
1111 }
1112
1113 void set_free_regions_coming();
1114 void reset_free_regions_coming();
1115 bool free_regions_coming() { return _free_regions_coming; }
1116 void wait_while_free_regions_coming();
1117
1118 // Perform a collection of the heap; intended for use in implementing
1119 // "System.gc". This probably implies as full a collection as the
1120 // "CollectedHeap" supports.
1121 virtual void collect(GCCause::Cause cause);
1122
1123 // The same as above but assume that the caller holds the Heap_lock.
1124 void collect_locked(GCCause::Cause cause);
1125
1126 // This interface assumes that it's being called by the
1127 // vm thread. It collects the heap assuming that the
1128 // heap lock is already held and that we are executing in
1129 // the context of the vm thread.
1130 virtual void collect_as_vm_thread(GCCause::Cause cause);
1131
1132 // True iff a evacuation has failed in the most-recent collection.
1133 bool evacuation_failed() { return _evacuation_failed; }
1134
1135 // It will free a region if it has allocated objects in it that are
1136 // all dead. It calls either free_region() or
1137 // free_humongous_region() depending on the type of the region that
1138 // is passed to it.
1139 void free_region_if_empty(HeapRegion* hr,
1140 size_t* pre_used,
1141 FreeRegionList* free_list,
1142 HumongousRegionSet* humongous_proxy_set,
1143 HRRSCleanupTask* hrrs_cleanup_task,
1144 bool par);
1145
1146 // It appends the free list to the master free list and updates the
1147 // master humongous list according to the contents of the proxy
1148 // list. It also adjusts the total used bytes according to pre_used
1149 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1150 void update_sets_after_freeing_regions(size_t pre_used,
1151 FreeRegionList* free_list,
1152 HumongousRegionSet* humongous_proxy_set,
1153 bool par);
1154
1155 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1156 virtual bool is_in(const void* p) const;
1157
1158 // Return "TRUE" iff the given object address is within the collection
1159 // set.
1160 inline bool obj_in_cs(oop obj);
1161
1162 // Return "TRUE" iff the given object address is in the reserved
1163 // region of g1 (excluding the permanent generation).
1164 bool is_in_g1_reserved(const void* p) const {
1165 return _g1_reserved.contains(p);
1166 }
1167
1168 // Returns a MemRegion that corresponds to the space that has been
1169 // reserved for the heap
1170 MemRegion g1_reserved() {
1171 return _g1_reserved;
1172 }
1173
1174 // Returns a MemRegion that corresponds to the space that has been
1175 // committed in the heap
1176 MemRegion g1_committed() {
1177 return _g1_committed;
1178 }
1179
1180 virtual bool is_in_closed_subset(const void* p) const;
1181
1182 // This resets the card table to all zeros. It is used after
1183 // a collection pause which used the card table to claim cards.
1184 void cleanUpCardTable();
1185
1186 // Iteration functions.
1187
1188 // Iterate over all the ref-containing fields of all objects, calling
1189 // "cl.do_oop" on each.
1190 virtual void oop_iterate(OopClosure* cl) {
1191 oop_iterate(cl, true);
1192 }
1193 void oop_iterate(OopClosure* cl, bool do_perm);
1194
1195 // Same as above, restricted to a memory region.
1196 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1197 oop_iterate(mr, cl, true);
1198 }
1199 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1200
1201 // Iterate over all objects, calling "cl.do_object" on each.
1202 virtual void object_iterate(ObjectClosure* cl) {
1203 object_iterate(cl, true);
1204 }
1205 virtual void safe_object_iterate(ObjectClosure* cl) {
1206 object_iterate(cl, true);
1207 }
1208 void object_iterate(ObjectClosure* cl, bool do_perm);
1209
1210 // Iterate over all objects allocated since the last collection, calling
1211 // "cl.do_object" on each. The heap must have been initialized properly
1212 // to support this function, or else this call will fail.
1213 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1214
1215 // Iterate over all spaces in use in the heap, in ascending address order.
1216 virtual void space_iterate(SpaceClosure* cl);
1217
1218 // Iterate over heap regions, in address order, terminating the
1219 // iteration early if the "doHeapRegion" method returns "true".
1220 void heap_region_iterate(HeapRegionClosure* blk) const;
1221
1222 // Iterate over heap regions starting with r (or the first region if "r"
1223 // is NULL), in address order, terminating early if the "doHeapRegion"
1224 // method returns "true".
1225 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1226
1227 // Return the region with the given index. It assumes the index is valid.
1228 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1229
1230 // Divide the heap region sequence into "chunks" of some size (the number
1231 // of regions divided by the number of parallel threads times some
1232 // overpartition factor, currently 4). Assumes that this will be called
1233 // in parallel by ParallelGCThreads worker threads with discinct worker
1234 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1235 // calls will use the same "claim_value", and that that claim value is
1236 // different from the claim_value of any heap region before the start of
1237 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1238 // attempting to claim the first region in each chunk, and, if
1239 // successful, applying the closure to each region in the chunk (and
1240 // setting the claim value of the second and subsequent regions of the
1241 // chunk.) For now requires that "doHeapRegion" always returns "false",
1242 // i.e., that a closure never attempt to abort a traversal.
1243 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1244 int worker,
1245 jint claim_value);
1246
1247 // It resets all the region claim values to the default.
1248 void reset_heap_region_claim_values();
1249
1250 #ifdef ASSERT
1251 bool check_heap_region_claim_values(jint claim_value);
1252 #endif // ASSERT
1253
1254 // Iterate over the regions (if any) in the current collection set.
1255 void collection_set_iterate(HeapRegionClosure* blk);
1256
1257 // As above but starting from region r
1258 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1259
1260 // Returns the first (lowest address) compactible space in the heap.
1261 virtual CompactibleSpace* first_compactible_space();
1262
1263 // A CollectedHeap will contain some number of spaces. This finds the
1264 // space containing a given address, or else returns NULL.
1265 virtual Space* space_containing(const void* addr) const;
1266
1267 // A G1CollectedHeap will contain some number of heap regions. This
1268 // finds the region containing a given address, or else returns NULL.
1269 template <class T>
1270 inline HeapRegion* heap_region_containing(const T addr) const;
1271
1272 // Like the above, but requires "addr" to be in the heap (to avoid a
1273 // null-check), and unlike the above, may return an continuing humongous
1274 // region.
1275 template <class T>
1276 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1277
1278 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1279 // each address in the (reserved) heap is a member of exactly
1280 // one block. The defining characteristic of a block is that it is
1281 // possible to find its size, and thus to progress forward to the next
1282 // block. (Blocks may be of different sizes.) Thus, blocks may
1283 // represent Java objects, or they might be free blocks in a
1284 // free-list-based heap (or subheap), as long as the two kinds are
1285 // distinguishable and the size of each is determinable.
1286
1287 // Returns the address of the start of the "block" that contains the
1288 // address "addr". We say "blocks" instead of "object" since some heaps
1289 // may not pack objects densely; a chunk may either be an object or a
1290 // non-object.
1291 virtual HeapWord* block_start(const void* addr) const;
1292
1293 // Requires "addr" to be the start of a chunk, and returns its size.
1294 // "addr + size" is required to be the start of a new chunk, or the end
1295 // of the active area of the heap.
1296 virtual size_t block_size(const HeapWord* addr) const;
1297
1298 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1299 // the block is an object.
1300 virtual bool block_is_obj(const HeapWord* addr) const;
1301
1302 // Does this heap support heap inspection? (+PrintClassHistogram)
1303 virtual bool supports_heap_inspection() const { return true; }
1304
1305 // Section on thread-local allocation buffers (TLABs)
1306 // See CollectedHeap for semantics.
1307
1308 virtual bool supports_tlab_allocation() const;
1309 virtual size_t tlab_capacity(Thread* thr) const;
1310 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1311
1312 // Can a compiler initialize a new object without store barriers?
1313 // This permission only extends from the creation of a new object
1314 // via a TLAB up to the first subsequent safepoint. If such permission
1315 // is granted for this heap type, the compiler promises to call
1316 // defer_store_barrier() below on any slow path allocation of
1317 // a new object for which such initializing store barriers will
1318 // have been elided. G1, like CMS, allows this, but should be
1319 // ready to provide a compensating write barrier as necessary
1320 // if that storage came out of a non-young region. The efficiency
1321 // of this implementation depends crucially on being able to
1322 // answer very efficiently in constant time whether a piece of
1323 // storage in the heap comes from a young region or not.
1324 // See ReduceInitialCardMarks.
1325 virtual bool can_elide_tlab_store_barriers() const {
1326 // 6920090: Temporarily disabled, because of lingering
1327 // instabilities related to RICM with G1. In the
1328 // interim, the option ReduceInitialCardMarksForG1
1329 // below is left solely as a debugging device at least
1330 // until 6920109 fixes the instabilities.
1331 return ReduceInitialCardMarksForG1;
1332 }
1333
1334 virtual bool card_mark_must_follow_store() const {
1335 return true;
1336 }
1337
1338 bool is_in_young(const oop obj) {
1339 HeapRegion* hr = heap_region_containing(obj);
1340 return hr != NULL && hr->is_young();
1341 }
1342
1343 #ifdef ASSERT
1344 virtual bool is_in_partial_collection(const void* p);
1345 #endif
1346
1347 virtual bool is_scavengable(const void* addr);
1348
1349 // We don't need barriers for initializing stores to objects
1350 // in the young gen: for the SATB pre-barrier, there is no
1351 // pre-value that needs to be remembered; for the remembered-set
1352 // update logging post-barrier, we don't maintain remembered set
1353 // information for young gen objects. Note that non-generational
1354 // G1 does not have any "young" objects, should not elide
1355 // the rs logging barrier and so should always answer false below.
1356 // However, non-generational G1 (-XX:-G1Gen) appears to have
1357 // bit-rotted so was not tested below.
1358 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1359 // Re 6920090, 6920109 above.
1360 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1361 assert(G1Gen || !is_in_young(new_obj),
1362 "Non-generational G1 should never return true below");
1363 return is_in_young(new_obj);
1364 }
1365
1366 // Can a compiler elide a store barrier when it writes
1367 // a permanent oop into the heap? Applies when the compiler
1368 // is storing x to the heap, where x->is_perm() is true.
1369 virtual bool can_elide_permanent_oop_store_barriers() const {
1370 // At least until perm gen collection is also G1-ified, at
1371 // which point this should return false.
1372 return true;
1373 }
1374
1375 // Returns "true" iff the given word_size is "very large".
1376 static bool isHumongous(size_t word_size) {
1377 // Note this has to be strictly greater-than as the TLABs
1378 // are capped at the humongous thresold and we want to
1379 // ensure that we don't try to allocate a TLAB as
1380 // humongous and that we don't allocate a humongous
1381 // object in a TLAB.
1382 return word_size > _humongous_object_threshold_in_words;
1383 }
1384
1385 // Update mod union table with the set of dirty cards.
1386 void updateModUnion();
1387
1388 // Set the mod union bits corresponding to the given memRegion. Note
1389 // that this is always a safe operation, since it doesn't clear any
1390 // bits.
1391 void markModUnionRange(MemRegion mr);
1392
1393 // Records the fact that a marking phase is no longer in progress.
1394 void set_marking_complete() {
1395 _mark_in_progress = false;
1396 }
1397 void set_marking_started() {
1398 _mark_in_progress = true;
1399 }
1400 bool mark_in_progress() {
1401 return _mark_in_progress;
1402 }
1403
1404 // Print the maximum heap capacity.
1405 virtual size_t max_capacity() const;
1406
1407 virtual jlong millis_since_last_gc();
1408
1409 // Perform any cleanup actions necessary before allowing a verification.
1410 virtual void prepare_for_verify();
1411
1412 // Perform verification.
1413
1414 // vo == UsePrevMarking -> use "prev" marking information,
1415 // vo == UseNextMarking -> use "next" marking information
1416 // vo == UseMarkWord -> use the mark word in the object header
1417 //
1418 // NOTE: Only the "prev" marking information is guaranteed to be
1419 // consistent most of the time, so most calls to this should use
1420 // vo == UsePrevMarking.
1421 // Currently, there is only one case where this is called with
1422 // vo == UseNextMarking, which is to verify the "next" marking
1423 // information at the end of remark.
1424 // Currently there is only one place where this is called with
1425 // vo == UseMarkWord, which is to verify the marking during a
1426 // full GC.
1427 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1428
1429 // Override; it uses the "prev" marking information
1430 virtual void verify(bool allow_dirty, bool silent);
1431 // Default behavior by calling print(tty);
1432 virtual void print() const;
1433 // This calls print_on(st, PrintHeapAtGCExtended).
1434 virtual void print_on(outputStream* st) const;
1435 // If extended is true, it will print out information for all
1436 // regions in the heap by calling print_on_extended(st).
1437 virtual void print_on(outputStream* st, bool extended) const;
1438 virtual void print_on_extended(outputStream* st) const;
1439
1440 virtual void print_gc_threads_on(outputStream* st) const;
1441 virtual void gc_threads_do(ThreadClosure* tc) const;
1442
1443 // Override
1444 void print_tracing_info() const;
1445
1446 // The following two methods are helpful for debugging RSet issues.
1447 void print_cset_rsets() PRODUCT_RETURN;
1448 void print_all_rsets() PRODUCT_RETURN;
1449
1450 // Convenience function to be used in situations where the heap type can be
1451 // asserted to be this type.
1452 static G1CollectedHeap* heap();
1453
1454 void empty_young_list();
1455
1456 void set_region_short_lived_locked(HeapRegion* hr);
1457 // add appropriate methods for any other surv rate groups
1458
1459 YoungList* young_list() { return _young_list; }
1460
1461 // debugging
1462 bool check_young_list_well_formed() {
1463 return _young_list->check_list_well_formed();
1464 }
1465
1466 bool check_young_list_empty(bool check_heap,
1467 bool check_sample = true);
1468
1469 // *** Stuff related to concurrent marking. It's not clear to me that so
1470 // many of these need to be public.
1471
1472 // The functions below are helper functions that a subclass of
1473 // "CollectedHeap" can use in the implementation of its virtual
1474 // functions.
1475 // This performs a concurrent marking of the live objects in a
1476 // bitmap off to the side.
1477 void doConcurrentMark();
1478
1479 // Do a full concurrent marking, synchronously.
1480 void do_sync_mark();
1481
1482 bool isMarkedPrev(oop obj) const;
1483 bool isMarkedNext(oop obj) const;
1484
1485 // vo == UsePrevMarking -> use "prev" marking information,
1486 // vo == UseNextMarking -> use "next" marking information,
1487 // vo == UseMarkWord -> use mark word from object header
1488 bool is_obj_dead_cond(const oop obj,
1489 const HeapRegion* hr,
1490 const VerifyOption vo) const {
1491
1492 switch (vo) {
1493 case VerifyOption_G1UsePrevMarking:
1494 return is_obj_dead(obj, hr);
1495 case VerifyOption_G1UseNextMarking:
1496 return is_obj_ill(obj, hr);
1497 default:
1498 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1499 return !obj->is_gc_marked();
1500 }
1501 }
1502
1503 // Determine if an object is dead, given the object and also
1504 // the region to which the object belongs. An object is dead
1505 // iff a) it was not allocated since the last mark and b) it
1506 // is not marked.
1507
1508 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1509 return
1510 !hr->obj_allocated_since_prev_marking(obj) &&
1511 !isMarkedPrev(obj);
1512 }
1513
1514 // This is used when copying an object to survivor space.
1515 // If the object is marked live, then we mark the copy live.
1516 // If the object is allocated since the start of this mark
1517 // cycle, then we mark the copy live.
1518 // If the object has been around since the previous mark
1519 // phase, and hasn't been marked yet during this phase,
1520 // then we don't mark it, we just wait for the
1521 // current marking cycle to get to it.
1522
1523 // This function returns true when an object has been
1524 // around since the previous marking and hasn't yet
1525 // been marked during this marking.
1526
1527 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1528 return
1529 !hr->obj_allocated_since_next_marking(obj) &&
1530 !isMarkedNext(obj);
1531 }
1532
1533 // Determine if an object is dead, given only the object itself.
1534 // This will find the region to which the object belongs and
1535 // then call the region version of the same function.
1536
1537 // Added if it is in permanent gen it isn't dead.
1538 // Added if it is NULL it isn't dead.
1539
1540 // vo == UsePrevMarking -> use "prev" marking information,
1541 // vo == UseNextMarking -> use "next" marking information,
1542 // vo == UseMarkWord -> use mark word from object header
1543 bool is_obj_dead_cond(const oop obj,
1544 const VerifyOption vo) const {
1545
1546 switch (vo) {
1547 case VerifyOption_G1UsePrevMarking:
1548 return is_obj_dead(obj);
1549 case VerifyOption_G1UseNextMarking:
1550 return is_obj_ill(obj);
1551 default:
1552 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1553 return !obj->is_gc_marked();
1554 }
1555 }
1556
1557 bool is_obj_dead(const oop obj) const {
1558 const HeapRegion* hr = heap_region_containing(obj);
1559 if (hr == NULL) {
1560 if (Universe::heap()->is_in_permanent(obj))
1561 return false;
1562 else if (obj == NULL) return false;
1563 else return true;
1564 }
1565 else return is_obj_dead(obj, hr);
1566 }
1567
1568 bool is_obj_ill(const oop obj) const {
1569 const HeapRegion* hr = heap_region_containing(obj);
1570 if (hr == NULL) {
1571 if (Universe::heap()->is_in_permanent(obj))
1572 return false;
1573 else if (obj == NULL) return false;
1574 else return true;
1575 }
1576 else return is_obj_ill(obj, hr);
1577 }
1578
1579 // The following is just to alert the verification code
1580 // that a full collection has occurred and that the
1581 // remembered sets are no longer up to date.
1582 bool _full_collection;
1583 void set_full_collection() { _full_collection = true;}
1584 void clear_full_collection() {_full_collection = false;}
1585 bool full_collection() {return _full_collection;}
1586
1587 ConcurrentMark* concurrent_mark() const { return _cm; }
1588 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1589
1590 // The dirty cards region list is used to record a subset of regions
1591 // whose cards need clearing. The list if populated during the
1592 // remembered set scanning and drained during the card table
1593 // cleanup. Although the methods are reentrant, population/draining
1594 // phases must not overlap. For synchronization purposes the last
1595 // element on the list points to itself.
1596 HeapRegion* _dirty_cards_region_list;
1597 void push_dirty_cards_region(HeapRegion* hr);
1598 HeapRegion* pop_dirty_cards_region();
1599
1600 public:
1601 void stop_conc_gc_threads();
1602
1603 // <NEW PREDICTION>
1604
1605 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1606 void check_if_region_is_too_expensive(double predicted_time_ms);
1607 size_t pending_card_num();
1608 size_t max_pending_card_num();
1609 size_t cards_scanned();
1610
1611 // </NEW PREDICTION>
1612
1613 protected:
1614 size_t _max_heap_capacity;
1615 };
1616
1617 #define use_local_bitmaps 1
1618 #define verify_local_bitmaps 0
1619 #define oop_buffer_length 256
1620
1621 #ifndef PRODUCT
1622 class GCLabBitMap;
1623 class GCLabBitMapClosure: public BitMapClosure {
1624 private:
1625 ConcurrentMark* _cm;
1626 GCLabBitMap* _bitmap;
1627
1628 public:
1629 GCLabBitMapClosure(ConcurrentMark* cm,
1630 GCLabBitMap* bitmap) {
1631 _cm = cm;
1632 _bitmap = bitmap;
1633 }
1634
1635 virtual bool do_bit(size_t offset);
1636 };
1637 #endif // !PRODUCT
1638
1639 class GCLabBitMap: public BitMap {
1640 private:
1641 ConcurrentMark* _cm;
1642
1643 int _shifter;
1644 size_t _bitmap_word_covers_words;
1645
1646 // beginning of the heap
1647 HeapWord* _heap_start;
1648
1649 // this is the actual start of the GCLab
1650 HeapWord* _real_start_word;
1651
1652 // this is the actual end of the GCLab
1653 HeapWord* _real_end_word;
1654
1655 // this is the first word, possibly located before the actual start
1656 // of the GCLab, that corresponds to the first bit of the bitmap
1657 HeapWord* _start_word;
1658
1659 // size of a GCLab in words
1660 size_t _gclab_word_size;
1661
1662 static int shifter() {
1663 return MinObjAlignment - 1;
1664 }
1665
1666 // how many heap words does a single bitmap word corresponds to?
1667 static size_t bitmap_word_covers_words() {
1668 return BitsPerWord << shifter();
1669 }
1670
1671 size_t gclab_word_size() const {
1672 return _gclab_word_size;
1673 }
1674
1675 // Calculates actual GCLab size in words
1676 size_t gclab_real_word_size() const {
1677 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1678 / BitsPerWord;
1679 }
1680
1681 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1682 size_t bits_in_bitmap = gclab_word_size >> shifter();
1683 // We are going to ensure that the beginning of a word in this
1684 // bitmap also corresponds to the beginning of a word in the
1685 // global marking bitmap. To handle the case where a GCLab
1686 // starts from the middle of the bitmap, we need to add enough
1687 // space (i.e. up to a bitmap word) to ensure that we have
1688 // enough bits in the bitmap.
1689 return bits_in_bitmap + BitsPerWord - 1;
1690 }
1691 public:
1692 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1693 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1694 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1695 _shifter(shifter()),
1696 _bitmap_word_covers_words(bitmap_word_covers_words()),
1697 _heap_start(heap_start),
1698 _gclab_word_size(gclab_word_size),
1699 _real_start_word(NULL),
1700 _real_end_word(NULL),
1701 _start_word(NULL)
1702 {
1703 guarantee( size_in_words() >= bitmap_size_in_words(),
1704 "just making sure");
1705 }
1706
1707 inline unsigned heapWordToOffset(HeapWord* addr) {
1708 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1709 assert(offset < size(), "offset should be within bounds");
1710 return offset;
1711 }
1712
1713 inline HeapWord* offsetToHeapWord(size_t offset) {
1714 HeapWord* addr = _start_word + (offset << _shifter);
1715 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1716 return addr;
1717 }
1718
1719 bool fields_well_formed() {
1720 bool ret1 = (_real_start_word == NULL) &&
1721 (_real_end_word == NULL) &&
1722 (_start_word == NULL);
1723 if (ret1)
1724 return true;
1725
1726 bool ret2 = _real_start_word >= _start_word &&
1727 _start_word < _real_end_word &&
1728 (_real_start_word + _gclab_word_size) == _real_end_word &&
1729 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1730 > _real_end_word;
1731 return ret2;
1732 }
1733
1734 inline bool mark(HeapWord* addr) {
1735 guarantee(use_local_bitmaps, "invariant");
1736 assert(fields_well_formed(), "invariant");
1737
1738 if (addr >= _real_start_word && addr < _real_end_word) {
1739 assert(!isMarked(addr), "should not have already been marked");
1740
1741 // first mark it on the bitmap
1742 at_put(heapWordToOffset(addr), true);
1743
1744 return true;
1745 } else {
1746 return false;
1747 }
1748 }
1749
1750 inline bool isMarked(HeapWord* addr) {
1751 guarantee(use_local_bitmaps, "invariant");
1752 assert(fields_well_formed(), "invariant");
1753
1754 return at(heapWordToOffset(addr));
1755 }
1756
1757 void set_buffer(HeapWord* start) {
1758 guarantee(use_local_bitmaps, "invariant");
1759 clear();
1760
1761 assert(start != NULL, "invariant");
1762 _real_start_word = start;
1763 _real_end_word = start + _gclab_word_size;
1764
1765 size_t diff =
1766 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1767 _start_word = start - diff;
1768
1769 assert(fields_well_formed(), "invariant");
1770 }
1771
1772 #ifndef PRODUCT
1773 void verify() {
1774 // verify that the marks have been propagated
1775 GCLabBitMapClosure cl(_cm, this);
1776 iterate(&cl);
1777 }
1778 #endif // PRODUCT
1779
1780 void retire() {
1781 guarantee(use_local_bitmaps, "invariant");
1782 assert(fields_well_formed(), "invariant");
1783
1784 if (_start_word != NULL) {
1785 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1786
1787 // this means that the bitmap was set up for the GCLab
1788 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1789
1790 mark_bitmap->mostly_disjoint_range_union(this,
1791 0, // always start from the start of the bitmap
1792 _start_word,
1793 gclab_real_word_size());
1794 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1795
1796 #ifndef PRODUCT
1797 if (use_local_bitmaps && verify_local_bitmaps)
1798 verify();
1799 #endif // PRODUCT
1800 } else {
1801 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1802 }
1803 }
1804
1805 size_t bitmap_size_in_words() const {
1806 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1807 }
1808
1809 };
1810
1811 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1812 private:
1813 bool _retired;
1814 bool _during_marking;
1815 GCLabBitMap _bitmap;
1816
1817 public:
1818 G1ParGCAllocBuffer(size_t gclab_word_size) :
1819 ParGCAllocBuffer(gclab_word_size),
1820 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1821 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1822 _retired(false)
1823 { }
1824
1825 inline bool mark(HeapWord* addr) {
1826 guarantee(use_local_bitmaps, "invariant");
1827 assert(_during_marking, "invariant");
1828 return _bitmap.mark(addr);
1829 }
1830
1831 inline void set_buf(HeapWord* buf) {
1832 if (use_local_bitmaps && _during_marking)
1833 _bitmap.set_buffer(buf);
1834 ParGCAllocBuffer::set_buf(buf);
1835 _retired = false;
1836 }
1837
1838 inline void retire(bool end_of_gc, bool retain) {
1839 if (_retired)
1840 return;
1841 if (use_local_bitmaps && _during_marking) {
1842 _bitmap.retire();
1843 }
1844 ParGCAllocBuffer::retire(end_of_gc, retain);
1845 _retired = true;
1846 }
1847 };
1848
1849 class G1ParScanThreadState : public StackObj {
1850 protected:
1851 G1CollectedHeap* _g1h;
1852 RefToScanQueue* _refs;
1853 DirtyCardQueue _dcq;
1854 CardTableModRefBS* _ct_bs;
1855 G1RemSet* _g1_rem;
1856
1857 G1ParGCAllocBuffer _surviving_alloc_buffer;
1858 G1ParGCAllocBuffer _tenured_alloc_buffer;
1859 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1860 ageTable _age_table;
1861
1862 size_t _alloc_buffer_waste;
1863 size_t _undo_waste;
1864
1865 OopsInHeapRegionClosure* _evac_failure_cl;
1866 G1ParScanHeapEvacClosure* _evac_cl;
1867 G1ParScanPartialArrayClosure* _partial_scan_cl;
1868
1869 int _hash_seed;
1870 int _queue_num;
1871
1872 size_t _term_attempts;
1873
1874 double _start;
1875 double _start_strong_roots;
1876 double _strong_roots_time;
1877 double _start_term;
1878 double _term_time;
1879
1880 // Map from young-age-index (0 == not young, 1 is youngest) to
1881 // surviving words. base is what we get back from the malloc call
1882 size_t* _surviving_young_words_base;
1883 // this points into the array, as we use the first few entries for padding
1884 size_t* _surviving_young_words;
1885
1886 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1887
1888 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1889
1890 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1891
1892 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1893 CardTableModRefBS* ctbs() { return _ct_bs; }
1894
1895 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1896 if (!from->is_survivor()) {
1897 _g1_rem->par_write_ref(from, p, tid);
1898 }
1899 }
1900
1901 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1902 // If the new value of the field points to the same region or
1903 // is the to-space, we don't need to include it in the Rset updates.
1904 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1905 size_t card_index = ctbs()->index_for(p);
1906 // If the card hasn't been added to the buffer, do it.
1907 if (ctbs()->mark_card_deferred(card_index)) {
1908 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1909 }
1910 }
1911 }
1912
1913 public:
1914 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1915
1916 ~G1ParScanThreadState() {
1917 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1918 }
1919
1920 RefToScanQueue* refs() { return _refs; }
1921 ageTable* age_table() { return &_age_table; }
1922
1923 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1924 return _alloc_buffers[purpose];
1925 }
1926
1927 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1928 size_t undo_waste() const { return _undo_waste; }
1929
1930 #ifdef ASSERT
1931 bool verify_ref(narrowOop* ref) const;
1932 bool verify_ref(oop* ref) const;
1933 bool verify_task(StarTask ref) const;
1934 #endif // ASSERT
1935
1936 template <class T> void push_on_queue(T* ref) {
1937 assert(verify_ref(ref), "sanity");
1938 refs()->push(ref);
1939 }
1940
1941 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1942 if (G1DeferredRSUpdate) {
1943 deferred_rs_update(from, p, tid);
1944 } else {
1945 immediate_rs_update(from, p, tid);
1946 }
1947 }
1948
1949 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1950
1951 HeapWord* obj = NULL;
1952 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1953 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1954 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1955 assert(gclab_word_size == alloc_buf->word_sz(),
1956 "dynamic resizing is not supported");
1957 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1958 alloc_buf->retire(false, false);
1959
1960 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1961 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1962 // Otherwise.
1963 alloc_buf->set_buf(buf);
1964
1965 obj = alloc_buf->allocate(word_sz);
1966 assert(obj != NULL, "buffer was definitely big enough...");
1967 } else {
1968 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1969 }
1970 return obj;
1971 }
1972
1973 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1974 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1975 if (obj != NULL) return obj;
1976 return allocate_slow(purpose, word_sz);
1977 }
1978
1979 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1980 if (alloc_buffer(purpose)->contains(obj)) {
1981 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1982 "should contain whole object");
1983 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1984 } else {
1985 CollectedHeap::fill_with_object(obj, word_sz);
1986 add_to_undo_waste(word_sz);
1987 }
1988 }
1989
1990 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1991 _evac_failure_cl = evac_failure_cl;
1992 }
1993 OopsInHeapRegionClosure* evac_failure_closure() {
1994 return _evac_failure_cl;
1995 }
1996
1997 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1998 _evac_cl = evac_cl;
1999 }
2000
2001 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2002 _partial_scan_cl = partial_scan_cl;
2003 }
2004
2005 int* hash_seed() { return &_hash_seed; }
2006 int queue_num() { return _queue_num; }
2007
2008 size_t term_attempts() const { return _term_attempts; }
2009 void note_term_attempt() { _term_attempts++; }
2010
2011 void start_strong_roots() {
2012 _start_strong_roots = os::elapsedTime();
2013 }
2014 void end_strong_roots() {
2015 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2016 }
2017 double strong_roots_time() const { return _strong_roots_time; }
2018
2019 void start_term_time() {
2020 note_term_attempt();
2021 _start_term = os::elapsedTime();
2022 }
2023 void end_term_time() {
2024 _term_time += (os::elapsedTime() - _start_term);
2025 }
2026 double term_time() const { return _term_time; }
2027
2028 double elapsed_time() const {
2029 return os::elapsedTime() - _start;
2030 }
2031
2032 static void
2033 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2034 void
2035 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2036
2037 size_t* surviving_young_words() {
2038 // We add on to hide entry 0 which accumulates surviving words for
2039 // age -1 regions (i.e. non-young ones)
2040 return _surviving_young_words;
2041 }
2042
2043 void retire_alloc_buffers() {
2044 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2045 size_t waste = _alloc_buffers[ap]->words_remaining();
2046 add_to_alloc_buffer_waste(waste);
2047 _alloc_buffers[ap]->retire(true, false);
2048 }
2049 }
2050
2051 template <class T> void deal_with_reference(T* ref_to_scan) {
2052 if (has_partial_array_mask(ref_to_scan)) {
2053 _partial_scan_cl->do_oop_nv(ref_to_scan);
2054 } else {
2055 // Note: we can use "raw" versions of "region_containing" because
2056 // "obj_to_scan" is definitely in the heap, and is not in a
2057 // humongous region.
2058 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2059 _evac_cl->set_region(r);
2060 _evac_cl->do_oop_nv(ref_to_scan);
2061 }
2062 }
2063
2064 void deal_with_reference(StarTask ref) {
2065 assert(verify_task(ref), "sanity");
2066 if (ref.is_narrow()) {
2067 deal_with_reference((narrowOop*)ref);
2068 } else {
2069 deal_with_reference((oop*)ref);
2070 }
2071 }
2072
2073 public:
2074 void trim_queue();
2075 };
2076
2077 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP