Fri, 16 Mar 2012 09:52:57 +0100
7130974: G1: Remove G1ParCopyHelper
Reviewed-by: tonyp, johnc
1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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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).
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
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"
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.
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;
65 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
77 class YoungList : public CHeapObj {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 size_t _length;
89 size_t _survivor_length;
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
94 void empty_list(HeapRegion* list);
96 public:
97 YoungList(G1CollectedHeap* g1h);
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
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; }
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 }
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
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 };
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 };
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 };
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 };
189 class RefineCardTableEntryClosure;
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;
201 // Closures used in implementation.
202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
203 friend class G1ParCopyClosure;
204 friend class G1IsAliveClosure;
205 friend class G1EvacuateFollowersClosure;
206 friend class G1ParScanThreadState;
207 friend class G1ParScanClosureSuper;
208 friend class G1ParEvacuateFollowersClosure;
209 friend class G1ParTask;
210 friend class G1FreeGarbageRegionClosure;
211 friend class RefineCardTableEntryClosure;
212 friend class G1PrepareCompactClosure;
213 friend class RegionSorter;
214 friend class RegionResetter;
215 friend class CountRCClosure;
216 friend class EvacPopObjClosure;
217 friend class G1ParCleanupCTTask;
219 // Other related classes.
220 friend class G1MarkSweep;
222 private:
223 // The one and only G1CollectedHeap, so static functions can find it.
224 static G1CollectedHeap* _g1h;
226 static size_t _humongous_object_threshold_in_words;
228 // Storage for the G1 heap (excludes the permanent generation).
229 VirtualSpace _g1_storage;
230 MemRegion _g1_reserved;
232 // The part of _g1_storage that is currently committed.
233 MemRegion _g1_committed;
235 // The master free list. It will satisfy all new region allocations.
236 MasterFreeRegionList _free_list;
238 // The secondary free list which contains regions that have been
239 // freed up during the cleanup process. This will be appended to the
240 // master free list when appropriate.
241 SecondaryFreeRegionList _secondary_free_list;
243 // It keeps track of the old regions.
244 MasterOldRegionSet _old_set;
246 // It keeps track of the humongous regions.
247 MasterHumongousRegionSet _humongous_set;
249 // The number of regions we could create by expansion.
250 size_t _expansion_regions;
252 // The block offset table for the G1 heap.
253 G1BlockOffsetSharedArray* _bot_shared;
255 // Tears down the region sets / lists so that they are empty and the
256 // regions on the heap do not belong to a region set / list. The
257 // only exception is the humongous set which we leave unaltered. If
258 // free_list_only is true, it will only tear down the master free
259 // list. It is called before a Full GC (free_list_only == false) or
260 // before heap shrinking (free_list_only == true).
261 void tear_down_region_sets(bool free_list_only);
263 // Rebuilds the region sets / lists so that they are repopulated to
264 // reflect the contents of the heap. The only exception is the
265 // humongous set which was not torn down in the first place. If
266 // free_list_only is true, it will only rebuild the master free
267 // list. It is called after a Full GC (free_list_only == false) or
268 // after heap shrinking (free_list_only == true).
269 void rebuild_region_sets(bool free_list_only);
271 // The sequence of all heap regions in the heap.
272 HeapRegionSeq _hrs;
274 // Alloc region used to satisfy mutator allocation requests.
275 MutatorAllocRegion _mutator_alloc_region;
277 // Alloc region used to satisfy allocation requests by the GC for
278 // survivor objects.
279 SurvivorGCAllocRegion _survivor_gc_alloc_region;
281 // Alloc region used to satisfy allocation requests by the GC for
282 // old objects.
283 OldGCAllocRegion _old_gc_alloc_region;
285 // The last old region we allocated to during the last GC.
286 // Typically, it is not full so we should re-use it during the next GC.
287 HeapRegion* _retained_old_gc_alloc_region;
289 // It specifies whether we should attempt to expand the heap after a
290 // region allocation failure. If heap expansion fails we set this to
291 // false so that we don't re-attempt the heap expansion (it's likely
292 // that subsequent expansion attempts will also fail if one fails).
293 // Currently, it is only consulted during GC and it's reset at the
294 // start of each GC.
295 bool _expand_heap_after_alloc_failure;
297 // It resets the mutator alloc region before new allocations can take place.
298 void init_mutator_alloc_region();
300 // It releases the mutator alloc region.
301 void release_mutator_alloc_region();
303 // It initializes the GC alloc regions at the start of a GC.
304 void init_gc_alloc_regions();
306 // It releases the GC alloc regions at the end of a GC.
307 void release_gc_alloc_regions();
309 // It does any cleanup that needs to be done on the GC alloc regions
310 // before a Full GC.
311 void abandon_gc_alloc_regions();
313 // Helper for monitoring and management support.
314 G1MonitoringSupport* _g1mm;
316 // Determines PLAB size for a particular allocation purpose.
317 static size_t desired_plab_sz(GCAllocPurpose purpose);
319 // Outside of GC pauses, the number of bytes used in all regions other
320 // than the current allocation region.
321 size_t _summary_bytes_used;
323 // This is used for a quick test on whether a reference points into
324 // the collection set or not. Basically, we have an array, with one
325 // byte per region, and that byte denotes whether the corresponding
326 // region is in the collection set or not. The entry corresponding
327 // the bottom of the heap, i.e., region 0, is pointed to by
328 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
329 // biased so that it actually points to address 0 of the address
330 // space, to make the test as fast as possible (we can simply shift
331 // the address to address into it, instead of having to subtract the
332 // bottom of the heap from the address before shifting it; basically
333 // it works in the same way the card table works).
334 bool* _in_cset_fast_test;
336 // The allocated array used for the fast test on whether a reference
337 // points into the collection set or not. This field is also used to
338 // free the array.
339 bool* _in_cset_fast_test_base;
341 // The length of the _in_cset_fast_test_base array.
342 size_t _in_cset_fast_test_length;
344 volatile unsigned _gc_time_stamp;
346 size_t* _surviving_young_words;
348 G1HRPrinter _hr_printer;
350 void setup_surviving_young_words();
351 void update_surviving_young_words(size_t* surv_young_words);
352 void cleanup_surviving_young_words();
354 // It decides whether an explicit GC should start a concurrent cycle
355 // instead of doing a STW GC. Currently, a concurrent cycle is
356 // explicitly started if:
357 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
358 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
359 // (c) cause == _g1_humongous_allocation
360 bool should_do_concurrent_full_gc(GCCause::Cause cause);
362 // Keeps track of how many "full collections" (i.e., Full GCs or
363 // concurrent cycles) we have completed. The number of them we have
364 // started is maintained in _total_full_collections in CollectedHeap.
365 volatile unsigned int _full_collections_completed;
367 // This is a non-product method that is helpful for testing. It is
368 // called at the end of a GC and artificially expands the heap by
369 // allocating a number of dead regions. This way we can induce very
370 // frequent marking cycles and stress the cleanup / concurrent
371 // cleanup code more (as all the regions that will be allocated by
372 // this method will be found dead by the marking cycle).
373 void allocate_dummy_regions() PRODUCT_RETURN;
375 // These are macros so that, if the assert fires, we get the correct
376 // line number, file, etc.
378 #define heap_locking_asserts_err_msg(_extra_message_) \
379 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
380 (_extra_message_), \
381 BOOL_TO_STR(Heap_lock->owned_by_self()), \
382 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
383 BOOL_TO_STR(Thread::current()->is_VM_thread()))
385 #define assert_heap_locked() \
386 do { \
387 assert(Heap_lock->owned_by_self(), \
388 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
389 } while (0)
391 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
392 do { \
393 assert(Heap_lock->owned_by_self() || \
394 (SafepointSynchronize::is_at_safepoint() && \
395 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
396 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
397 "should be at a safepoint")); \
398 } while (0)
400 #define assert_heap_locked_and_not_at_safepoint() \
401 do { \
402 assert(Heap_lock->owned_by_self() && \
403 !SafepointSynchronize::is_at_safepoint(), \
404 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
405 "should not be at a safepoint")); \
406 } while (0)
408 #define assert_heap_not_locked() \
409 do { \
410 assert(!Heap_lock->owned_by_self(), \
411 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
412 } while (0)
414 #define assert_heap_not_locked_and_not_at_safepoint() \
415 do { \
416 assert(!Heap_lock->owned_by_self() && \
417 !SafepointSynchronize::is_at_safepoint(), \
418 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
419 "should not be at a safepoint")); \
420 } while (0)
422 #define assert_at_safepoint(_should_be_vm_thread_) \
423 do { \
424 assert(SafepointSynchronize::is_at_safepoint() && \
425 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
426 heap_locking_asserts_err_msg("should be at a safepoint")); \
427 } while (0)
429 #define assert_not_at_safepoint() \
430 do { \
431 assert(!SafepointSynchronize::is_at_safepoint(), \
432 heap_locking_asserts_err_msg("should not be at a safepoint")); \
433 } while (0)
435 protected:
437 // The young region list.
438 YoungList* _young_list;
440 // The current policy object for the collector.
441 G1CollectorPolicy* _g1_policy;
443 // This is the second level of trying to allocate a new region. If
444 // new_region() didn't find a region on the free_list, this call will
445 // check whether there's anything available on the
446 // secondary_free_list and/or wait for more regions to appear on
447 // that list, if _free_regions_coming is set.
448 HeapRegion* new_region_try_secondary_free_list();
450 // Try to allocate a single non-humongous HeapRegion sufficient for
451 // an allocation of the given word_size. If do_expand is true,
452 // attempt to expand the heap if necessary to satisfy the allocation
453 // request.
454 HeapRegion* new_region(size_t word_size, bool do_expand);
456 // Attempt to satisfy a humongous allocation request of the given
457 // size by finding a contiguous set of free regions of num_regions
458 // length and remove them from the master free list. Return the
459 // index of the first region or G1_NULL_HRS_INDEX if the search
460 // was unsuccessful.
461 size_t humongous_obj_allocate_find_first(size_t num_regions,
462 size_t word_size);
464 // Initialize a contiguous set of free regions of length num_regions
465 // and starting at index first so that they appear as a single
466 // humongous region.
467 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
468 size_t num_regions,
469 size_t word_size);
471 // Attempt to allocate a humongous object of the given size. Return
472 // NULL if unsuccessful.
473 HeapWord* humongous_obj_allocate(size_t word_size);
475 // The following two methods, allocate_new_tlab() and
476 // mem_allocate(), are the two main entry points from the runtime
477 // into the G1's allocation routines. They have the following
478 // assumptions:
479 //
480 // * They should both be called outside safepoints.
481 //
482 // * They should both be called without holding the Heap_lock.
483 //
484 // * All allocation requests for new TLABs should go to
485 // allocate_new_tlab().
486 //
487 // * All non-TLAB allocation requests should go to mem_allocate().
488 //
489 // * If either call cannot satisfy the allocation request using the
490 // current allocating region, they will try to get a new one. If
491 // this fails, they will attempt to do an evacuation pause and
492 // retry the allocation.
493 //
494 // * If all allocation attempts fail, even after trying to schedule
495 // an evacuation pause, allocate_new_tlab() will return NULL,
496 // whereas mem_allocate() will attempt a heap expansion and/or
497 // schedule a Full GC.
498 //
499 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
500 // should never be called with word_size being humongous. All
501 // humongous allocation requests should go to mem_allocate() which
502 // will satisfy them with a special path.
504 virtual HeapWord* allocate_new_tlab(size_t word_size);
506 virtual HeapWord* mem_allocate(size_t word_size,
507 bool* gc_overhead_limit_was_exceeded);
509 // The following three methods take a gc_count_before_ret
510 // parameter which is used to return the GC count if the method
511 // returns NULL. Given that we are required to read the GC count
512 // while holding the Heap_lock, and these paths will take the
513 // Heap_lock at some point, it's easier to get them to read the GC
514 // count while holding the Heap_lock before they return NULL instead
515 // of the caller (namely: mem_allocate()) having to also take the
516 // Heap_lock just to read the GC count.
518 // First-level mutator allocation attempt: try to allocate out of
519 // the mutator alloc region without taking the Heap_lock. This
520 // should only be used for non-humongous allocations.
521 inline HeapWord* attempt_allocation(size_t word_size,
522 unsigned int* gc_count_before_ret);
524 // Second-level mutator allocation attempt: take the Heap_lock and
525 // retry the allocation attempt, potentially scheduling a GC
526 // pause. This should only be used for non-humongous allocations.
527 HeapWord* attempt_allocation_slow(size_t word_size,
528 unsigned int* gc_count_before_ret);
530 // Takes the Heap_lock and attempts a humongous allocation. It can
531 // potentially schedule a GC pause.
532 HeapWord* attempt_allocation_humongous(size_t word_size,
533 unsigned int* gc_count_before_ret);
535 // Allocation attempt that should be called during safepoints (e.g.,
536 // at the end of a successful GC). expect_null_mutator_alloc_region
537 // specifies whether the mutator alloc region is expected to be NULL
538 // or not.
539 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
540 bool expect_null_mutator_alloc_region);
542 // It dirties the cards that cover the block so that so that the post
543 // write barrier never queues anything when updating objects on this
544 // block. It is assumed (and in fact we assert) that the block
545 // belongs to a young region.
546 inline void dirty_young_block(HeapWord* start, size_t word_size);
548 // Allocate blocks during garbage collection. Will ensure an
549 // allocation region, either by picking one or expanding the
550 // heap, and then allocate a block of the given size. The block
551 // may not be a humongous - it must fit into a single heap region.
552 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
554 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
555 HeapRegion* alloc_region,
556 bool par,
557 size_t word_size);
559 // Ensure that no further allocations can happen in "r", bearing in mind
560 // that parallel threads might be attempting allocations.
561 void par_allocate_remaining_space(HeapRegion* r);
563 // Allocation attempt during GC for a survivor object / PLAB.
564 inline HeapWord* survivor_attempt_allocation(size_t word_size);
566 // Allocation attempt during GC for an old object / PLAB.
567 inline HeapWord* old_attempt_allocation(size_t word_size);
569 // These methods are the "callbacks" from the G1AllocRegion class.
571 // For mutator alloc regions.
572 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
573 void retire_mutator_alloc_region(HeapRegion* alloc_region,
574 size_t allocated_bytes);
576 // For GC alloc regions.
577 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
578 GCAllocPurpose ap);
579 void retire_gc_alloc_region(HeapRegion* alloc_region,
580 size_t allocated_bytes, GCAllocPurpose ap);
582 // - if explicit_gc is true, the GC is for a System.gc() or a heap
583 // inspection request and should collect the entire heap
584 // - if clear_all_soft_refs is true, all soft references should be
585 // cleared during the GC
586 // - if explicit_gc is false, word_size describes the allocation that
587 // the GC should attempt (at least) to satisfy
588 // - it returns false if it is unable to do the collection due to the
589 // GC locker being active, true otherwise
590 bool do_collection(bool explicit_gc,
591 bool clear_all_soft_refs,
592 size_t word_size);
594 // Callback from VM_G1CollectFull operation.
595 // Perform a full collection.
596 void do_full_collection(bool clear_all_soft_refs);
598 // Resize the heap if necessary after a full collection. If this is
599 // after a collect-for allocation, "word_size" is the allocation size,
600 // and will be considered part of the used portion of the heap.
601 void resize_if_necessary_after_full_collection(size_t word_size);
603 // Callback from VM_G1CollectForAllocation operation.
604 // This function does everything necessary/possible to satisfy a
605 // failed allocation request (including collection, expansion, etc.)
606 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
608 // Attempting to expand the heap sufficiently
609 // to support an allocation of the given "word_size". If
610 // successful, perform the allocation and return the address of the
611 // allocated block, or else "NULL".
612 HeapWord* expand_and_allocate(size_t word_size);
614 // Process any reference objects discovered during
615 // an incremental evacuation pause.
616 void process_discovered_references();
618 // Enqueue any remaining discovered references
619 // after processing.
620 void enqueue_discovered_references();
622 public:
624 G1MonitoringSupport* g1mm() {
625 assert(_g1mm != NULL, "should have been initialized");
626 return _g1mm;
627 }
629 // Expand the garbage-first heap by at least the given size (in bytes!).
630 // Returns true if the heap was expanded by the requested amount;
631 // false otherwise.
632 // (Rounds up to a HeapRegion boundary.)
633 bool expand(size_t expand_bytes);
635 // Do anything common to GC's.
636 virtual void gc_prologue(bool full);
637 virtual void gc_epilogue(bool full);
639 // We register a region with the fast "in collection set" test. We
640 // simply set to true the array slot corresponding to this region.
641 void register_region_with_in_cset_fast_test(HeapRegion* r) {
642 assert(_in_cset_fast_test_base != NULL, "sanity");
643 assert(r->in_collection_set(), "invariant");
644 size_t index = r->hrs_index();
645 assert(index < _in_cset_fast_test_length, "invariant");
646 assert(!_in_cset_fast_test_base[index], "invariant");
647 _in_cset_fast_test_base[index] = true;
648 }
650 // This is a fast test on whether a reference points into the
651 // collection set or not. It does not assume that the reference
652 // points into the heap; if it doesn't, it will return false.
653 bool in_cset_fast_test(oop obj) {
654 assert(_in_cset_fast_test != NULL, "sanity");
655 if (_g1_committed.contains((HeapWord*) obj)) {
656 // no need to subtract the bottom of the heap from obj,
657 // _in_cset_fast_test is biased
658 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
659 bool ret = _in_cset_fast_test[index];
660 // let's make sure the result is consistent with what the slower
661 // test returns
662 assert( ret || !obj_in_cs(obj), "sanity");
663 assert(!ret || obj_in_cs(obj), "sanity");
664 return ret;
665 } else {
666 return false;
667 }
668 }
670 void clear_cset_fast_test() {
671 assert(_in_cset_fast_test_base != NULL, "sanity");
672 memset(_in_cset_fast_test_base, false,
673 _in_cset_fast_test_length * sizeof(bool));
674 }
676 // This is called at the end of either a concurrent cycle or a Full
677 // GC to update the number of full collections completed. Those two
678 // can happen in a nested fashion, i.e., we start a concurrent
679 // cycle, a Full GC happens half-way through it which ends first,
680 // and then the cycle notices that a Full GC happened and ends
681 // too. The concurrent parameter is a boolean to help us do a bit
682 // tighter consistency checking in the method. If concurrent is
683 // false, the caller is the inner caller in the nesting (i.e., the
684 // Full GC). If concurrent is true, the caller is the outer caller
685 // in this nesting (i.e., the concurrent cycle). Further nesting is
686 // not currently supported. The end of the this call also notifies
687 // the FullGCCount_lock in case a Java thread is waiting for a full
688 // GC to happen (e.g., it called System.gc() with
689 // +ExplicitGCInvokesConcurrent).
690 void increment_full_collections_completed(bool concurrent);
692 unsigned int full_collections_completed() {
693 return _full_collections_completed;
694 }
696 G1HRPrinter* hr_printer() { return &_hr_printer; }
698 protected:
700 // Shrink the garbage-first heap by at most the given size (in bytes!).
701 // (Rounds down to a HeapRegion boundary.)
702 virtual void shrink(size_t expand_bytes);
703 void shrink_helper(size_t expand_bytes);
705 #if TASKQUEUE_STATS
706 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
707 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
708 void reset_taskqueue_stats();
709 #endif // TASKQUEUE_STATS
711 // Schedule the VM operation that will do an evacuation pause to
712 // satisfy an allocation request of word_size. *succeeded will
713 // return whether the VM operation was successful (it did do an
714 // evacuation pause) or not (another thread beat us to it or the GC
715 // locker was active). Given that we should not be holding the
716 // Heap_lock when we enter this method, we will pass the
717 // gc_count_before (i.e., total_collections()) as a parameter since
718 // it has to be read while holding the Heap_lock. Currently, both
719 // methods that call do_collection_pause() release the Heap_lock
720 // before the call, so it's easy to read gc_count_before just before.
721 HeapWord* do_collection_pause(size_t word_size,
722 unsigned int gc_count_before,
723 bool* succeeded);
725 // The guts of the incremental collection pause, executed by the vm
726 // thread. It returns false if it is unable to do the collection due
727 // to the GC locker being active, true otherwise
728 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
730 // Actually do the work of evacuating the collection set.
731 void evacuate_collection_set();
733 // The g1 remembered set of the heap.
734 G1RemSet* _g1_rem_set;
735 // And it's mod ref barrier set, used to track updates for the above.
736 ModRefBarrierSet* _mr_bs;
738 // A set of cards that cover the objects for which the Rsets should be updated
739 // concurrently after the collection.
740 DirtyCardQueueSet _dirty_card_queue_set;
742 // The Heap Region Rem Set Iterator.
743 HeapRegionRemSetIterator** _rem_set_iterator;
745 // The closure used to refine a single card.
746 RefineCardTableEntryClosure* _refine_cte_cl;
748 // A function to check the consistency of dirty card logs.
749 void check_ct_logs_at_safepoint();
751 // A DirtyCardQueueSet that is used to hold cards that contain
752 // references into the current collection set. This is used to
753 // update the remembered sets of the regions in the collection
754 // set in the event of an evacuation failure.
755 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
757 // After a collection pause, make the regions in the CS into free
758 // regions.
759 void free_collection_set(HeapRegion* cs_head);
761 // Abandon the current collection set without recording policy
762 // statistics or updating free lists.
763 void abandon_collection_set(HeapRegion* cs_head);
765 // Applies "scan_non_heap_roots" to roots outside the heap,
766 // "scan_rs" to roots inside the heap (having done "set_region" to
767 // indicate the region in which the root resides), and does "scan_perm"
768 // (setting the generation to the perm generation.) If "scan_rs" is
769 // NULL, then this step is skipped. The "worker_i"
770 // param is for use with parallel roots processing, and should be
771 // the "i" of the calling parallel worker thread's work(i) function.
772 // In the sequential case this param will be ignored.
773 void g1_process_strong_roots(bool collecting_perm_gen,
774 ScanningOption so,
775 OopClosure* scan_non_heap_roots,
776 OopsInHeapRegionClosure* scan_rs,
777 OopsInGenClosure* scan_perm,
778 int worker_i);
780 // Apply "blk" to all the weak roots of the system. These include
781 // JNI weak roots, the code cache, system dictionary, symbol table,
782 // string table, and referents of reachable weak refs.
783 void g1_process_weak_roots(OopClosure* root_closure,
784 OopClosure* non_root_closure);
786 // Frees a non-humongous region by initializing its contents and
787 // adding it to the free list that's passed as a parameter (this is
788 // usually a local list which will be appended to the master free
789 // list later). The used bytes of freed regions are accumulated in
790 // pre_used. If par is true, the region's RSet will not be freed
791 // up. The assumption is that this will be done later.
792 void free_region(HeapRegion* hr,
793 size_t* pre_used,
794 FreeRegionList* free_list,
795 bool par);
797 // Frees a humongous region by collapsing it into individual regions
798 // and calling free_region() for each of them. The freed regions
799 // will be added to the free list that's passed as a parameter (this
800 // is usually a local list which will be appended to the master free
801 // list later). The used bytes of freed regions are accumulated in
802 // pre_used. If par is true, the region's RSet will not be freed
803 // up. The assumption is that this will be done later.
804 void free_humongous_region(HeapRegion* hr,
805 size_t* pre_used,
806 FreeRegionList* free_list,
807 HumongousRegionSet* humongous_proxy_set,
808 bool par);
810 // Notifies all the necessary spaces that the committed space has
811 // been updated (either expanded or shrunk). It should be called
812 // after _g1_storage is updated.
813 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
815 // The concurrent marker (and the thread it runs in.)
816 ConcurrentMark* _cm;
817 ConcurrentMarkThread* _cmThread;
818 bool _mark_in_progress;
820 // The concurrent refiner.
821 ConcurrentG1Refine* _cg1r;
823 // The parallel task queues
824 RefToScanQueueSet *_task_queues;
826 // True iff a evacuation has failed in the current collection.
827 bool _evacuation_failed;
829 // Set the attribute indicating whether evacuation has failed in the
830 // current collection.
831 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
833 // Failed evacuations cause some logical from-space objects to have
834 // forwarding pointers to themselves. Reset them.
835 void remove_self_forwarding_pointers();
837 // When one is non-null, so is the other. Together, they each pair is
838 // an object with a preserved mark, and its mark value.
839 GrowableArray<oop>* _objs_with_preserved_marks;
840 GrowableArray<markOop>* _preserved_marks_of_objs;
842 // Preserve the mark of "obj", if necessary, in preparation for its mark
843 // word being overwritten with a self-forwarding-pointer.
844 void preserve_mark_if_necessary(oop obj, markOop m);
846 // The stack of evac-failure objects left to be scanned.
847 GrowableArray<oop>* _evac_failure_scan_stack;
848 // The closure to apply to evac-failure objects.
850 OopsInHeapRegionClosure* _evac_failure_closure;
851 // Set the field above.
852 void
853 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
854 _evac_failure_closure = evac_failure_closure;
855 }
857 // Push "obj" on the scan stack.
858 void push_on_evac_failure_scan_stack(oop obj);
859 // Process scan stack entries until the stack is empty.
860 void drain_evac_failure_scan_stack();
861 // True iff an invocation of "drain_scan_stack" is in progress; to
862 // prevent unnecessary recursion.
863 bool _drain_in_progress;
865 // Do any necessary initialization for evacuation-failure handling.
866 // "cl" is the closure that will be used to process evac-failure
867 // objects.
868 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
869 // Do any necessary cleanup for evacuation-failure handling data
870 // structures.
871 void finalize_for_evac_failure();
873 // An attempt to evacuate "obj" has failed; take necessary steps.
874 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
875 void handle_evacuation_failure_common(oop obj, markOop m);
877 // ("Weak") Reference processing support.
878 //
879 // G1 has 2 instances of the referece processor class. One
880 // (_ref_processor_cm) handles reference object discovery
881 // and subsequent processing during concurrent marking cycles.
882 //
883 // The other (_ref_processor_stw) handles reference object
884 // discovery and processing during full GCs and incremental
885 // evacuation pauses.
886 //
887 // During an incremental pause, reference discovery will be
888 // temporarily disabled for _ref_processor_cm and will be
889 // enabled for _ref_processor_stw. At the end of the evacuation
890 // pause references discovered by _ref_processor_stw will be
891 // processed and discovery will be disabled. The previous
892 // setting for reference object discovery for _ref_processor_cm
893 // will be re-instated.
894 //
895 // At the start of marking:
896 // * Discovery by the CM ref processor is verified to be inactive
897 // and it's discovered lists are empty.
898 // * Discovery by the CM ref processor is then enabled.
899 //
900 // At the end of marking:
901 // * Any references on the CM ref processor's discovered
902 // lists are processed (possibly MT).
903 //
904 // At the start of full GC we:
905 // * Disable discovery by the CM ref processor and
906 // empty CM ref processor's discovered lists
907 // (without processing any entries).
908 // * Verify that the STW ref processor is inactive and it's
909 // discovered lists are empty.
910 // * Temporarily set STW ref processor discovery as single threaded.
911 // * Temporarily clear the STW ref processor's _is_alive_non_header
912 // field.
913 // * Finally enable discovery by the STW ref processor.
914 //
915 // The STW ref processor is used to record any discovered
916 // references during the full GC.
917 //
918 // At the end of a full GC we:
919 // * Enqueue any reference objects discovered by the STW ref processor
920 // that have non-live referents. This has the side-effect of
921 // making the STW ref processor inactive by disabling discovery.
922 // * Verify that the CM ref processor is still inactive
923 // and no references have been placed on it's discovered
924 // lists (also checked as a precondition during initial marking).
926 // The (stw) reference processor...
927 ReferenceProcessor* _ref_processor_stw;
929 // During reference object discovery, the _is_alive_non_header
930 // closure (if non-null) is applied to the referent object to
931 // determine whether the referent is live. If so then the
932 // reference object does not need to be 'discovered' and can
933 // be treated as a regular oop. This has the benefit of reducing
934 // the number of 'discovered' reference objects that need to
935 // be processed.
936 //
937 // Instance of the is_alive closure for embedding into the
938 // STW reference processor as the _is_alive_non_header field.
939 // Supplying a value for the _is_alive_non_header field is
940 // optional but doing so prevents unnecessary additions to
941 // the discovered lists during reference discovery.
942 G1STWIsAliveClosure _is_alive_closure_stw;
944 // The (concurrent marking) reference processor...
945 ReferenceProcessor* _ref_processor_cm;
947 // Instance of the concurrent mark is_alive closure for embedding
948 // into the Concurrent Marking reference processor as the
949 // _is_alive_non_header field. Supplying a value for the
950 // _is_alive_non_header field is optional but doing so prevents
951 // unnecessary additions to the discovered lists during reference
952 // discovery.
953 G1CMIsAliveClosure _is_alive_closure_cm;
955 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
956 HeapRegion** _worker_cset_start_region;
958 // Time stamp to validate the regions recorded in the cache
959 // used by G1CollectedHeap::start_cset_region_for_worker().
960 // The heap region entry for a given worker is valid iff
961 // the associated time stamp value matches the current value
962 // of G1CollectedHeap::_gc_time_stamp.
963 unsigned int* _worker_cset_start_region_time_stamp;
965 enum G1H_process_strong_roots_tasks {
966 G1H_PS_filter_satb_buffers,
967 G1H_PS_refProcessor_oops_do,
968 // Leave this one last.
969 G1H_PS_NumElements
970 };
972 SubTasksDone* _process_strong_tasks;
974 volatile bool _free_regions_coming;
976 public:
978 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
980 void set_refine_cte_cl_concurrency(bool concurrent);
982 RefToScanQueue *task_queue(int i) const;
984 // A set of cards where updates happened during the GC
985 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
987 // A DirtyCardQueueSet that is used to hold cards that contain
988 // references into the current collection set. This is used to
989 // update the remembered sets of the regions in the collection
990 // set in the event of an evacuation failure.
991 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
992 { return _into_cset_dirty_card_queue_set; }
994 // Create a G1CollectedHeap with the specified policy.
995 // Must call the initialize method afterwards.
996 // May not return if something goes wrong.
997 G1CollectedHeap(G1CollectorPolicy* policy);
999 // Initialize the G1CollectedHeap to have the initial and
1000 // maximum sizes, permanent generation, and remembered and barrier sets
1001 // specified by the policy object.
1002 jint initialize();
1004 // Initialize weak reference processing.
1005 virtual void ref_processing_init();
1007 void set_par_threads(uint t) {
1008 SharedHeap::set_par_threads(t);
1009 // Done in SharedHeap but oddly there are
1010 // two _process_strong_tasks's in a G1CollectedHeap
1011 // so do it here too.
1012 _process_strong_tasks->set_n_threads(t);
1013 }
1015 // Set _n_par_threads according to a policy TBD.
1016 void set_par_threads();
1018 void set_n_termination(int t) {
1019 _process_strong_tasks->set_n_threads(t);
1020 }
1022 virtual CollectedHeap::Name kind() const {
1023 return CollectedHeap::G1CollectedHeap;
1024 }
1026 // The current policy object for the collector.
1027 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1029 // Adaptive size policy. No such thing for g1.
1030 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1032 // The rem set and barrier set.
1033 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1034 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1036 // The rem set iterator.
1037 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1038 return _rem_set_iterator[i];
1039 }
1041 HeapRegionRemSetIterator* rem_set_iterator() {
1042 return _rem_set_iterator[0];
1043 }
1045 unsigned get_gc_time_stamp() {
1046 return _gc_time_stamp;
1047 }
1049 void reset_gc_time_stamp() {
1050 _gc_time_stamp = 0;
1051 OrderAccess::fence();
1052 // Clear the cached CSet starting regions and time stamps.
1053 // Their validity is dependent on the GC timestamp.
1054 clear_cset_start_regions();
1055 }
1057 void increment_gc_time_stamp() {
1058 ++_gc_time_stamp;
1059 OrderAccess::fence();
1060 }
1062 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1063 DirtyCardQueue* into_cset_dcq,
1064 bool concurrent, int worker_i);
1066 // The shared block offset table array.
1067 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1069 // Reference Processing accessors
1071 // The STW reference processor....
1072 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1074 // The Concurent Marking reference processor...
1075 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1077 virtual size_t capacity() const;
1078 virtual size_t used() const;
1079 // This should be called when we're not holding the heap lock. The
1080 // result might be a bit inaccurate.
1081 size_t used_unlocked() const;
1082 size_t recalculate_used() const;
1084 // These virtual functions do the actual allocation.
1085 // Some heaps may offer a contiguous region for shared non-blocking
1086 // allocation, via inlined code (by exporting the address of the top and
1087 // end fields defining the extent of the contiguous allocation region.)
1088 // But G1CollectedHeap doesn't yet support this.
1090 // Return an estimate of the maximum allocation that could be performed
1091 // without triggering any collection or expansion activity. In a
1092 // generational collector, for example, this is probably the largest
1093 // allocation that could be supported (without expansion) in the youngest
1094 // generation. It is "unsafe" because no locks are taken; the result
1095 // should be treated as an approximation, not a guarantee, for use in
1096 // heuristic resizing decisions.
1097 virtual size_t unsafe_max_alloc();
1099 virtual bool is_maximal_no_gc() const {
1100 return _g1_storage.uncommitted_size() == 0;
1101 }
1103 // The total number of regions in the heap.
1104 size_t n_regions() { return _hrs.length(); }
1106 // The max number of regions in the heap.
1107 size_t max_regions() { return _hrs.max_length(); }
1109 // The number of regions that are completely free.
1110 size_t free_regions() { return _free_list.length(); }
1112 // The number of regions that are not completely free.
1113 size_t used_regions() { return n_regions() - free_regions(); }
1115 // The number of regions available for "regular" expansion.
1116 size_t expansion_regions() { return _expansion_regions; }
1118 // Factory method for HeapRegion instances. It will return NULL if
1119 // the allocation fails.
1120 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1122 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1123 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1124 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1125 void verify_dirty_young_regions() PRODUCT_RETURN;
1127 // verify_region_sets() performs verification over the region
1128 // lists. It will be compiled in the product code to be used when
1129 // necessary (i.e., during heap verification).
1130 void verify_region_sets();
1132 // verify_region_sets_optional() is planted in the code for
1133 // list verification in non-product builds (and it can be enabled in
1134 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1135 #if HEAP_REGION_SET_FORCE_VERIFY
1136 void verify_region_sets_optional() {
1137 verify_region_sets();
1138 }
1139 #else // HEAP_REGION_SET_FORCE_VERIFY
1140 void verify_region_sets_optional() { }
1141 #endif // HEAP_REGION_SET_FORCE_VERIFY
1143 #ifdef ASSERT
1144 bool is_on_master_free_list(HeapRegion* hr) {
1145 return hr->containing_set() == &_free_list;
1146 }
1148 bool is_in_humongous_set(HeapRegion* hr) {
1149 return hr->containing_set() == &_humongous_set;
1150 }
1151 #endif // ASSERT
1153 // Wrapper for the region list operations that can be called from
1154 // methods outside this class.
1156 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1157 _secondary_free_list.add_as_tail(list);
1158 }
1160 void append_secondary_free_list() {
1161 _free_list.add_as_head(&_secondary_free_list);
1162 }
1164 void append_secondary_free_list_if_not_empty_with_lock() {
1165 // If the secondary free list looks empty there's no reason to
1166 // take the lock and then try to append it.
1167 if (!_secondary_free_list.is_empty()) {
1168 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1169 append_secondary_free_list();
1170 }
1171 }
1173 void old_set_remove(HeapRegion* hr) {
1174 _old_set.remove(hr);
1175 }
1177 size_t non_young_capacity_bytes() {
1178 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1179 }
1181 void set_free_regions_coming();
1182 void reset_free_regions_coming();
1183 bool free_regions_coming() { return _free_regions_coming; }
1184 void wait_while_free_regions_coming();
1186 // Determine whether the given region is one that we are using as an
1187 // old GC alloc region.
1188 bool is_old_gc_alloc_region(HeapRegion* hr) {
1189 return hr == _retained_old_gc_alloc_region;
1190 }
1192 // Perform a collection of the heap; intended for use in implementing
1193 // "System.gc". This probably implies as full a collection as the
1194 // "CollectedHeap" supports.
1195 virtual void collect(GCCause::Cause cause);
1197 // The same as above but assume that the caller holds the Heap_lock.
1198 void collect_locked(GCCause::Cause cause);
1200 // This interface assumes that it's being called by the
1201 // vm thread. It collects the heap assuming that the
1202 // heap lock is already held and that we are executing in
1203 // the context of the vm thread.
1204 virtual void collect_as_vm_thread(GCCause::Cause cause);
1206 // True iff a evacuation has failed in the most-recent collection.
1207 bool evacuation_failed() { return _evacuation_failed; }
1209 // It will free a region if it has allocated objects in it that are
1210 // all dead. It calls either free_region() or
1211 // free_humongous_region() depending on the type of the region that
1212 // is passed to it.
1213 void free_region_if_empty(HeapRegion* hr,
1214 size_t* pre_used,
1215 FreeRegionList* free_list,
1216 OldRegionSet* old_proxy_set,
1217 HumongousRegionSet* humongous_proxy_set,
1218 HRRSCleanupTask* hrrs_cleanup_task,
1219 bool par);
1221 // It appends the free list to the master free list and updates the
1222 // master humongous list according to the contents of the proxy
1223 // list. It also adjusts the total used bytes according to pre_used
1224 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1225 void update_sets_after_freeing_regions(size_t pre_used,
1226 FreeRegionList* free_list,
1227 OldRegionSet* old_proxy_set,
1228 HumongousRegionSet* humongous_proxy_set,
1229 bool par);
1231 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1232 virtual bool is_in(const void* p) const;
1234 // Return "TRUE" iff the given object address is within the collection
1235 // set.
1236 inline bool obj_in_cs(oop obj);
1238 // Return "TRUE" iff the given object address is in the reserved
1239 // region of g1 (excluding the permanent generation).
1240 bool is_in_g1_reserved(const void* p) const {
1241 return _g1_reserved.contains(p);
1242 }
1244 // Returns a MemRegion that corresponds to the space that has been
1245 // reserved for the heap
1246 MemRegion g1_reserved() {
1247 return _g1_reserved;
1248 }
1250 // Returns a MemRegion that corresponds to the space that has been
1251 // committed in the heap
1252 MemRegion g1_committed() {
1253 return _g1_committed;
1254 }
1256 virtual bool is_in_closed_subset(const void* p) const;
1258 // This resets the card table to all zeros. It is used after
1259 // a collection pause which used the card table to claim cards.
1260 void cleanUpCardTable();
1262 // Iteration functions.
1264 // Iterate over all the ref-containing fields of all objects, calling
1265 // "cl.do_oop" on each.
1266 virtual void oop_iterate(OopClosure* cl) {
1267 oop_iterate(cl, true);
1268 }
1269 void oop_iterate(OopClosure* cl, bool do_perm);
1271 // Same as above, restricted to a memory region.
1272 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1273 oop_iterate(mr, cl, true);
1274 }
1275 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1277 // Iterate over all objects, calling "cl.do_object" on each.
1278 virtual void object_iterate(ObjectClosure* cl) {
1279 object_iterate(cl, true);
1280 }
1281 virtual void safe_object_iterate(ObjectClosure* cl) {
1282 object_iterate(cl, true);
1283 }
1284 void object_iterate(ObjectClosure* cl, bool do_perm);
1286 // Iterate over all objects allocated since the last collection, calling
1287 // "cl.do_object" on each. The heap must have been initialized properly
1288 // to support this function, or else this call will fail.
1289 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1291 // Iterate over all spaces in use in the heap, in ascending address order.
1292 virtual void space_iterate(SpaceClosure* cl);
1294 // Iterate over heap regions, in address order, terminating the
1295 // iteration early if the "doHeapRegion" method returns "true".
1296 void heap_region_iterate(HeapRegionClosure* blk) const;
1298 // Iterate over heap regions starting with r (or the first region if "r"
1299 // is NULL), in address order, terminating early if the "doHeapRegion"
1300 // method returns "true".
1301 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1303 // Return the region with the given index. It assumes the index is valid.
1304 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1306 // Divide the heap region sequence into "chunks" of some size (the number
1307 // of regions divided by the number of parallel threads times some
1308 // overpartition factor, currently 4). Assumes that this will be called
1309 // in parallel by ParallelGCThreads worker threads with discinct worker
1310 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1311 // calls will use the same "claim_value", and that that claim value is
1312 // different from the claim_value of any heap region before the start of
1313 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1314 // attempting to claim the first region in each chunk, and, if
1315 // successful, applying the closure to each region in the chunk (and
1316 // setting the claim value of the second and subsequent regions of the
1317 // chunk.) For now requires that "doHeapRegion" always returns "false",
1318 // i.e., that a closure never attempt to abort a traversal.
1319 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1320 uint worker,
1321 uint no_of_par_workers,
1322 jint claim_value);
1324 // It resets all the region claim values to the default.
1325 void reset_heap_region_claim_values();
1327 // Resets the claim values of regions in the current
1328 // collection set to the default.
1329 void reset_cset_heap_region_claim_values();
1331 #ifdef ASSERT
1332 bool check_heap_region_claim_values(jint claim_value);
1334 // Same as the routine above but only checks regions in the
1335 // current collection set.
1336 bool check_cset_heap_region_claim_values(jint claim_value);
1337 #endif // ASSERT
1339 // Clear the cached cset start regions and (more importantly)
1340 // the time stamps. Called when we reset the GC time stamp.
1341 void clear_cset_start_regions();
1343 // Given the id of a worker, obtain or calculate a suitable
1344 // starting region for iterating over the current collection set.
1345 HeapRegion* start_cset_region_for_worker(int worker_i);
1347 // Iterate over the regions (if any) in the current collection set.
1348 void collection_set_iterate(HeapRegionClosure* blk);
1350 // As above but starting from region r
1351 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1353 // Returns the first (lowest address) compactible space in the heap.
1354 virtual CompactibleSpace* first_compactible_space();
1356 // A CollectedHeap will contain some number of spaces. This finds the
1357 // space containing a given address, or else returns NULL.
1358 virtual Space* space_containing(const void* addr) const;
1360 // A G1CollectedHeap will contain some number of heap regions. This
1361 // finds the region containing a given address, or else returns NULL.
1362 template <class T>
1363 inline HeapRegion* heap_region_containing(const T addr) const;
1365 // Like the above, but requires "addr" to be in the heap (to avoid a
1366 // null-check), and unlike the above, may return an continuing humongous
1367 // region.
1368 template <class T>
1369 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1371 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1372 // each address in the (reserved) heap is a member of exactly
1373 // one block. The defining characteristic of a block is that it is
1374 // possible to find its size, and thus to progress forward to the next
1375 // block. (Blocks may be of different sizes.) Thus, blocks may
1376 // represent Java objects, or they might be free blocks in a
1377 // free-list-based heap (or subheap), as long as the two kinds are
1378 // distinguishable and the size of each is determinable.
1380 // Returns the address of the start of the "block" that contains the
1381 // address "addr". We say "blocks" instead of "object" since some heaps
1382 // may not pack objects densely; a chunk may either be an object or a
1383 // non-object.
1384 virtual HeapWord* block_start(const void* addr) const;
1386 // Requires "addr" to be the start of a chunk, and returns its size.
1387 // "addr + size" is required to be the start of a new chunk, or the end
1388 // of the active area of the heap.
1389 virtual size_t block_size(const HeapWord* addr) const;
1391 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1392 // the block is an object.
1393 virtual bool block_is_obj(const HeapWord* addr) const;
1395 // Does this heap support heap inspection? (+PrintClassHistogram)
1396 virtual bool supports_heap_inspection() const { return true; }
1398 // Section on thread-local allocation buffers (TLABs)
1399 // See CollectedHeap for semantics.
1401 virtual bool supports_tlab_allocation() const;
1402 virtual size_t tlab_capacity(Thread* thr) const;
1403 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1405 // Can a compiler initialize a new object without store barriers?
1406 // This permission only extends from the creation of a new object
1407 // via a TLAB up to the first subsequent safepoint. If such permission
1408 // is granted for this heap type, the compiler promises to call
1409 // defer_store_barrier() below on any slow path allocation of
1410 // a new object for which such initializing store barriers will
1411 // have been elided. G1, like CMS, allows this, but should be
1412 // ready to provide a compensating write barrier as necessary
1413 // if that storage came out of a non-young region. The efficiency
1414 // of this implementation depends crucially on being able to
1415 // answer very efficiently in constant time whether a piece of
1416 // storage in the heap comes from a young region or not.
1417 // See ReduceInitialCardMarks.
1418 virtual bool can_elide_tlab_store_barriers() const {
1419 return true;
1420 }
1422 virtual bool card_mark_must_follow_store() const {
1423 return true;
1424 }
1426 bool is_in_young(const oop obj) {
1427 HeapRegion* hr = heap_region_containing(obj);
1428 return hr != NULL && hr->is_young();
1429 }
1431 #ifdef ASSERT
1432 virtual bool is_in_partial_collection(const void* p);
1433 #endif
1435 virtual bool is_scavengable(const void* addr);
1437 // We don't need barriers for initializing stores to objects
1438 // in the young gen: for the SATB pre-barrier, there is no
1439 // pre-value that needs to be remembered; for the remembered-set
1440 // update logging post-barrier, we don't maintain remembered set
1441 // information for young gen objects.
1442 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1443 return is_in_young(new_obj);
1444 }
1446 // Can a compiler elide a store barrier when it writes
1447 // a permanent oop into the heap? Applies when the compiler
1448 // is storing x to the heap, where x->is_perm() is true.
1449 virtual bool can_elide_permanent_oop_store_barriers() const {
1450 // At least until perm gen collection is also G1-ified, at
1451 // which point this should return false.
1452 return true;
1453 }
1455 // Returns "true" iff the given word_size is "very large".
1456 static bool isHumongous(size_t word_size) {
1457 // Note this has to be strictly greater-than as the TLABs
1458 // are capped at the humongous thresold and we want to
1459 // ensure that we don't try to allocate a TLAB as
1460 // humongous and that we don't allocate a humongous
1461 // object in a TLAB.
1462 return word_size > _humongous_object_threshold_in_words;
1463 }
1465 // Update mod union table with the set of dirty cards.
1466 void updateModUnion();
1468 // Set the mod union bits corresponding to the given memRegion. Note
1469 // that this is always a safe operation, since it doesn't clear any
1470 // bits.
1471 void markModUnionRange(MemRegion mr);
1473 // Records the fact that a marking phase is no longer in progress.
1474 void set_marking_complete() {
1475 _mark_in_progress = false;
1476 }
1477 void set_marking_started() {
1478 _mark_in_progress = true;
1479 }
1480 bool mark_in_progress() {
1481 return _mark_in_progress;
1482 }
1484 // Print the maximum heap capacity.
1485 virtual size_t max_capacity() const;
1487 virtual jlong millis_since_last_gc();
1489 // Perform any cleanup actions necessary before allowing a verification.
1490 virtual void prepare_for_verify();
1492 // Perform verification.
1494 // vo == UsePrevMarking -> use "prev" marking information,
1495 // vo == UseNextMarking -> use "next" marking information
1496 // vo == UseMarkWord -> use the mark word in the object header
1497 //
1498 // NOTE: Only the "prev" marking information is guaranteed to be
1499 // consistent most of the time, so most calls to this should use
1500 // vo == UsePrevMarking.
1501 // Currently, there is only one case where this is called with
1502 // vo == UseNextMarking, which is to verify the "next" marking
1503 // information at the end of remark.
1504 // Currently there is only one place where this is called with
1505 // vo == UseMarkWord, which is to verify the marking during a
1506 // full GC.
1507 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1509 // Override; it uses the "prev" marking information
1510 virtual void verify(bool allow_dirty, bool silent);
1511 virtual void print_on(outputStream* st) const;
1512 virtual void print_extended_on(outputStream* st) const;
1514 virtual void print_gc_threads_on(outputStream* st) const;
1515 virtual void gc_threads_do(ThreadClosure* tc) const;
1517 // Override
1518 void print_tracing_info() const;
1520 // The following two methods are helpful for debugging RSet issues.
1521 void print_cset_rsets() PRODUCT_RETURN;
1522 void print_all_rsets() PRODUCT_RETURN;
1524 // Convenience function to be used in situations where the heap type can be
1525 // asserted to be this type.
1526 static G1CollectedHeap* heap();
1528 void set_region_short_lived_locked(HeapRegion* hr);
1529 // add appropriate methods for any other surv rate groups
1531 YoungList* young_list() { return _young_list; }
1533 // debugging
1534 bool check_young_list_well_formed() {
1535 return _young_list->check_list_well_formed();
1536 }
1538 bool check_young_list_empty(bool check_heap,
1539 bool check_sample = true);
1541 // *** Stuff related to concurrent marking. It's not clear to me that so
1542 // many of these need to be public.
1544 // The functions below are helper functions that a subclass of
1545 // "CollectedHeap" can use in the implementation of its virtual
1546 // functions.
1547 // This performs a concurrent marking of the live objects in a
1548 // bitmap off to the side.
1549 void doConcurrentMark();
1551 bool isMarkedPrev(oop obj) const;
1552 bool isMarkedNext(oop obj) const;
1554 // vo == UsePrevMarking -> use "prev" marking information,
1555 // vo == UseNextMarking -> use "next" marking information,
1556 // vo == UseMarkWord -> use mark word from object header
1557 bool is_obj_dead_cond(const oop obj,
1558 const HeapRegion* hr,
1559 const VerifyOption vo) const {
1561 switch (vo) {
1562 case VerifyOption_G1UsePrevMarking:
1563 return is_obj_dead(obj, hr);
1564 case VerifyOption_G1UseNextMarking:
1565 return is_obj_ill(obj, hr);
1566 default:
1567 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1568 return !obj->is_gc_marked();
1569 }
1570 }
1572 // Determine if an object is dead, given the object and also
1573 // the region to which the object belongs. An object is dead
1574 // iff a) it was not allocated since the last mark and b) it
1575 // is not marked.
1577 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1578 return
1579 !hr->obj_allocated_since_prev_marking(obj) &&
1580 !isMarkedPrev(obj);
1581 }
1583 // This is used when copying an object to survivor space.
1584 // If the object is marked live, then we mark the copy live.
1585 // If the object is allocated since the start of this mark
1586 // cycle, then we mark the copy live.
1587 // If the object has been around since the previous mark
1588 // phase, and hasn't been marked yet during this phase,
1589 // then we don't mark it, we just wait for the
1590 // current marking cycle to get to it.
1592 // This function returns true when an object has been
1593 // around since the previous marking and hasn't yet
1594 // been marked during this marking.
1596 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1597 return
1598 !hr->obj_allocated_since_next_marking(obj) &&
1599 !isMarkedNext(obj);
1600 }
1602 // Determine if an object is dead, given only the object itself.
1603 // This will find the region to which the object belongs and
1604 // then call the region version of the same function.
1606 // Added if it is in permanent gen it isn't dead.
1607 // Added if it is NULL it isn't dead.
1609 // vo == UsePrevMarking -> use "prev" marking information,
1610 // vo == UseNextMarking -> use "next" marking information,
1611 // vo == UseMarkWord -> use mark word from object header
1612 bool is_obj_dead_cond(const oop obj,
1613 const VerifyOption vo) const {
1615 switch (vo) {
1616 case VerifyOption_G1UsePrevMarking:
1617 return is_obj_dead(obj);
1618 case VerifyOption_G1UseNextMarking:
1619 return is_obj_ill(obj);
1620 default:
1621 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1622 return !obj->is_gc_marked();
1623 }
1624 }
1626 bool is_obj_dead(const oop obj) const {
1627 const HeapRegion* hr = heap_region_containing(obj);
1628 if (hr == NULL) {
1629 if (Universe::heap()->is_in_permanent(obj))
1630 return false;
1631 else if (obj == NULL) return false;
1632 else return true;
1633 }
1634 else return is_obj_dead(obj, hr);
1635 }
1637 bool is_obj_ill(const oop obj) const {
1638 const HeapRegion* hr = heap_region_containing(obj);
1639 if (hr == NULL) {
1640 if (Universe::heap()->is_in_permanent(obj))
1641 return false;
1642 else if (obj == NULL) return false;
1643 else return true;
1644 }
1645 else return is_obj_ill(obj, hr);
1646 }
1648 // The following is just to alert the verification code
1649 // that a full collection has occurred and that the
1650 // remembered sets are no longer up to date.
1651 bool _full_collection;
1652 void set_full_collection() { _full_collection = true;}
1653 void clear_full_collection() {_full_collection = false;}
1654 bool full_collection() {return _full_collection;}
1656 ConcurrentMark* concurrent_mark() const { return _cm; }
1657 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1659 // The dirty cards region list is used to record a subset of regions
1660 // whose cards need clearing. The list if populated during the
1661 // remembered set scanning and drained during the card table
1662 // cleanup. Although the methods are reentrant, population/draining
1663 // phases must not overlap. For synchronization purposes the last
1664 // element on the list points to itself.
1665 HeapRegion* _dirty_cards_region_list;
1666 void push_dirty_cards_region(HeapRegion* hr);
1667 HeapRegion* pop_dirty_cards_region();
1669 public:
1670 void stop_conc_gc_threads();
1672 size_t pending_card_num();
1673 size_t max_pending_card_num();
1674 size_t cards_scanned();
1676 protected:
1677 size_t _max_heap_capacity;
1678 };
1680 #define use_local_bitmaps 1
1681 #define verify_local_bitmaps 0
1682 #define oop_buffer_length 256
1684 #ifndef PRODUCT
1685 class GCLabBitMap;
1686 class GCLabBitMapClosure: public BitMapClosure {
1687 private:
1688 ConcurrentMark* _cm;
1689 GCLabBitMap* _bitmap;
1691 public:
1692 GCLabBitMapClosure(ConcurrentMark* cm,
1693 GCLabBitMap* bitmap) {
1694 _cm = cm;
1695 _bitmap = bitmap;
1696 }
1698 virtual bool do_bit(size_t offset);
1699 };
1700 #endif // !PRODUCT
1702 class GCLabBitMap: public BitMap {
1703 private:
1704 ConcurrentMark* _cm;
1706 int _shifter;
1707 size_t _bitmap_word_covers_words;
1709 // beginning of the heap
1710 HeapWord* _heap_start;
1712 // this is the actual start of the GCLab
1713 HeapWord* _real_start_word;
1715 // this is the actual end of the GCLab
1716 HeapWord* _real_end_word;
1718 // this is the first word, possibly located before the actual start
1719 // of the GCLab, that corresponds to the first bit of the bitmap
1720 HeapWord* _start_word;
1722 // size of a GCLab in words
1723 size_t _gclab_word_size;
1725 static int shifter() {
1726 return MinObjAlignment - 1;
1727 }
1729 // how many heap words does a single bitmap word corresponds to?
1730 static size_t bitmap_word_covers_words() {
1731 return BitsPerWord << shifter();
1732 }
1734 size_t gclab_word_size() const {
1735 return _gclab_word_size;
1736 }
1738 // Calculates actual GCLab size in words
1739 size_t gclab_real_word_size() const {
1740 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1741 / BitsPerWord;
1742 }
1744 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1745 size_t bits_in_bitmap = gclab_word_size >> shifter();
1746 // We are going to ensure that the beginning of a word in this
1747 // bitmap also corresponds to the beginning of a word in the
1748 // global marking bitmap. To handle the case where a GCLab
1749 // starts from the middle of the bitmap, we need to add enough
1750 // space (i.e. up to a bitmap word) to ensure that we have
1751 // enough bits in the bitmap.
1752 return bits_in_bitmap + BitsPerWord - 1;
1753 }
1754 public:
1755 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1756 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1757 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1758 _shifter(shifter()),
1759 _bitmap_word_covers_words(bitmap_word_covers_words()),
1760 _heap_start(heap_start),
1761 _gclab_word_size(gclab_word_size),
1762 _real_start_word(NULL),
1763 _real_end_word(NULL),
1764 _start_word(NULL) {
1765 guarantee(false, "GCLabBitMap::GCLabBitmap(): don't call this any more");
1766 }
1768 inline unsigned heapWordToOffset(HeapWord* addr) {
1769 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1770 assert(offset < size(), "offset should be within bounds");
1771 return offset;
1772 }
1774 inline HeapWord* offsetToHeapWord(size_t offset) {
1775 HeapWord* addr = _start_word + (offset << _shifter);
1776 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1777 return addr;
1778 }
1780 bool fields_well_formed() {
1781 bool ret1 = (_real_start_word == NULL) &&
1782 (_real_end_word == NULL) &&
1783 (_start_word == NULL);
1784 if (ret1)
1785 return true;
1787 bool ret2 = _real_start_word >= _start_word &&
1788 _start_word < _real_end_word &&
1789 (_real_start_word + _gclab_word_size) == _real_end_word &&
1790 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1791 > _real_end_word;
1792 return ret2;
1793 }
1795 inline bool mark(HeapWord* addr) {
1796 guarantee(use_local_bitmaps, "invariant");
1797 assert(fields_well_formed(), "invariant");
1799 if (addr >= _real_start_word && addr < _real_end_word) {
1800 assert(!isMarked(addr), "should not have already been marked");
1802 // first mark it on the bitmap
1803 at_put(heapWordToOffset(addr), true);
1805 return true;
1806 } else {
1807 return false;
1808 }
1809 }
1811 inline bool isMarked(HeapWord* addr) {
1812 guarantee(use_local_bitmaps, "invariant");
1813 assert(fields_well_formed(), "invariant");
1815 return at(heapWordToOffset(addr));
1816 }
1818 void set_buffer(HeapWord* start) {
1819 guarantee(false, "set_buffer(): don't call this any more");
1821 guarantee(use_local_bitmaps, "invariant");
1822 clear();
1824 assert(start != NULL, "invariant");
1825 _real_start_word = start;
1826 _real_end_word = start + _gclab_word_size;
1828 size_t diff =
1829 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1830 _start_word = start - diff;
1832 assert(fields_well_formed(), "invariant");
1833 }
1835 #ifndef PRODUCT
1836 void verify() {
1837 // verify that the marks have been propagated
1838 GCLabBitMapClosure cl(_cm, this);
1839 iterate(&cl);
1840 }
1841 #endif // PRODUCT
1843 void retire() {
1844 guarantee(false, "retire(): don't call this any more");
1846 guarantee(use_local_bitmaps, "invariant");
1847 assert(fields_well_formed(), "invariant");
1849 if (_start_word != NULL) {
1850 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1852 // this means that the bitmap was set up for the GCLab
1853 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1855 mark_bitmap->mostly_disjoint_range_union(this,
1856 0, // always start from the start of the bitmap
1857 _start_word,
1858 gclab_real_word_size());
1859 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1861 #ifndef PRODUCT
1862 if (use_local_bitmaps && verify_local_bitmaps)
1863 verify();
1864 #endif // PRODUCT
1865 } else {
1866 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1867 }
1868 }
1870 size_t bitmap_size_in_words() const {
1871 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1872 }
1874 };
1876 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1877 private:
1878 bool _retired;
1880 public:
1881 G1ParGCAllocBuffer(size_t gclab_word_size);
1883 void set_buf(HeapWord* buf) {
1884 ParGCAllocBuffer::set_buf(buf);
1885 _retired = false;
1886 }
1888 void retire(bool end_of_gc, bool retain) {
1889 if (_retired)
1890 return;
1891 ParGCAllocBuffer::retire(end_of_gc, retain);
1892 _retired = true;
1893 }
1894 };
1896 class G1ParScanThreadState : public StackObj {
1897 protected:
1898 G1CollectedHeap* _g1h;
1899 RefToScanQueue* _refs;
1900 DirtyCardQueue _dcq;
1901 CardTableModRefBS* _ct_bs;
1902 G1RemSet* _g1_rem;
1904 G1ParGCAllocBuffer _surviving_alloc_buffer;
1905 G1ParGCAllocBuffer _tenured_alloc_buffer;
1906 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1907 ageTable _age_table;
1909 size_t _alloc_buffer_waste;
1910 size_t _undo_waste;
1912 OopsInHeapRegionClosure* _evac_failure_cl;
1913 G1ParScanHeapEvacClosure* _evac_cl;
1914 G1ParScanPartialArrayClosure* _partial_scan_cl;
1916 int _hash_seed;
1917 uint _queue_num;
1919 size_t _term_attempts;
1921 double _start;
1922 double _start_strong_roots;
1923 double _strong_roots_time;
1924 double _start_term;
1925 double _term_time;
1927 // Map from young-age-index (0 == not young, 1 is youngest) to
1928 // surviving words. base is what we get back from the malloc call
1929 size_t* _surviving_young_words_base;
1930 // this points into the array, as we use the first few entries for padding
1931 size_t* _surviving_young_words;
1933 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1935 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1937 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1939 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1940 CardTableModRefBS* ctbs() { return _ct_bs; }
1942 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1943 if (!from->is_survivor()) {
1944 _g1_rem->par_write_ref(from, p, tid);
1945 }
1946 }
1948 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1949 // If the new value of the field points to the same region or
1950 // is the to-space, we don't need to include it in the Rset updates.
1951 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1952 size_t card_index = ctbs()->index_for(p);
1953 // If the card hasn't been added to the buffer, do it.
1954 if (ctbs()->mark_card_deferred(card_index)) {
1955 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1956 }
1957 }
1958 }
1960 public:
1961 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1963 ~G1ParScanThreadState() {
1964 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1965 }
1967 RefToScanQueue* refs() { return _refs; }
1968 ageTable* age_table() { return &_age_table; }
1970 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1971 return _alloc_buffers[purpose];
1972 }
1974 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1975 size_t undo_waste() const { return _undo_waste; }
1977 #ifdef ASSERT
1978 bool verify_ref(narrowOop* ref) const;
1979 bool verify_ref(oop* ref) const;
1980 bool verify_task(StarTask ref) const;
1981 #endif // ASSERT
1983 template <class T> void push_on_queue(T* ref) {
1984 assert(verify_ref(ref), "sanity");
1985 refs()->push(ref);
1986 }
1988 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1989 if (G1DeferredRSUpdate) {
1990 deferred_rs_update(from, p, tid);
1991 } else {
1992 immediate_rs_update(from, p, tid);
1993 }
1994 }
1996 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1998 HeapWord* obj = NULL;
1999 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
2000 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
2001 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
2002 assert(gclab_word_size == alloc_buf->word_sz(),
2003 "dynamic resizing is not supported");
2004 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
2005 alloc_buf->retire(false, false);
2007 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
2008 if (buf == NULL) return NULL; // Let caller handle allocation failure.
2009 // Otherwise.
2010 alloc_buf->set_buf(buf);
2012 obj = alloc_buf->allocate(word_sz);
2013 assert(obj != NULL, "buffer was definitely big enough...");
2014 } else {
2015 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
2016 }
2017 return obj;
2018 }
2020 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
2021 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
2022 if (obj != NULL) return obj;
2023 return allocate_slow(purpose, word_sz);
2024 }
2026 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
2027 if (alloc_buffer(purpose)->contains(obj)) {
2028 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2029 "should contain whole object");
2030 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2031 } else {
2032 CollectedHeap::fill_with_object(obj, word_sz);
2033 add_to_undo_waste(word_sz);
2034 }
2035 }
2037 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2038 _evac_failure_cl = evac_failure_cl;
2039 }
2040 OopsInHeapRegionClosure* evac_failure_closure() {
2041 return _evac_failure_cl;
2042 }
2044 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2045 _evac_cl = evac_cl;
2046 }
2048 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2049 _partial_scan_cl = partial_scan_cl;
2050 }
2052 int* hash_seed() { return &_hash_seed; }
2053 uint queue_num() { return _queue_num; }
2055 size_t term_attempts() const { return _term_attempts; }
2056 void note_term_attempt() { _term_attempts++; }
2058 void start_strong_roots() {
2059 _start_strong_roots = os::elapsedTime();
2060 }
2061 void end_strong_roots() {
2062 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2063 }
2064 double strong_roots_time() const { return _strong_roots_time; }
2066 void start_term_time() {
2067 note_term_attempt();
2068 _start_term = os::elapsedTime();
2069 }
2070 void end_term_time() {
2071 _term_time += (os::elapsedTime() - _start_term);
2072 }
2073 double term_time() const { return _term_time; }
2075 double elapsed_time() const {
2076 return os::elapsedTime() - _start;
2077 }
2079 static void
2080 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2081 void
2082 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2084 size_t* surviving_young_words() {
2085 // We add on to hide entry 0 which accumulates surviving words for
2086 // age -1 regions (i.e. non-young ones)
2087 return _surviving_young_words;
2088 }
2090 void retire_alloc_buffers() {
2091 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2092 size_t waste = _alloc_buffers[ap]->words_remaining();
2093 add_to_alloc_buffer_waste(waste);
2094 _alloc_buffers[ap]->retire(true, false);
2095 }
2096 }
2098 template <class T> void deal_with_reference(T* ref_to_scan) {
2099 if (has_partial_array_mask(ref_to_scan)) {
2100 _partial_scan_cl->do_oop_nv(ref_to_scan);
2101 } else {
2102 // Note: we can use "raw" versions of "region_containing" because
2103 // "obj_to_scan" is definitely in the heap, and is not in a
2104 // humongous region.
2105 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2106 _evac_cl->set_region(r);
2107 _evac_cl->do_oop_nv(ref_to_scan);
2108 }
2109 }
2111 void deal_with_reference(StarTask ref) {
2112 assert(verify_task(ref), "sanity");
2113 if (ref.is_narrow()) {
2114 deal_with_reference((narrowOop*)ref);
2115 } else {
2116 deal_with_reference((oop*)ref);
2117 }
2118 }
2120 public:
2121 void trim_queue();
2122 };
2124 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP