Tue, 21 Jun 2011 15:23:07 -0400
7046182: G1: remove unnecessary iterations over the collection set
Summary: Remove two unnecessary iterations over the collection set which are supposed to prepare the RSet's of the CSet regions for parallel iterations (we'll make sure this is done incrementally). I'll piggyback on this CR the removal of the G1_REM_SET_LOGGING code.
Reviewed-by: brutisso, johnc
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.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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/g1RemSet.hpp"
31 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.hpp"
33 #include "gc_implementation/g1/heapRegionSets.hpp"
34 #include "gc_implementation/shared/hSpaceCounters.hpp"
35 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
36 #include "memory/barrierSet.hpp"
37 #include "memory/memRegion.hpp"
38 #include "memory/sharedHeap.hpp"
40 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
41 // It uses the "Garbage First" heap organization and algorithm, which
42 // may combine concurrent marking with parallel, incremental compaction of
43 // heap subsets that will yield large amounts of garbage.
45 class HeapRegion;
46 class HRRSCleanupTask;
47 class PermanentGenerationSpec;
48 class GenerationSpec;
49 class OopsInHeapRegionClosure;
50 class G1ScanHeapEvacClosure;
51 class ObjectClosure;
52 class SpaceClosure;
53 class CompactibleSpaceClosure;
54 class Space;
55 class G1CollectorPolicy;
56 class GenRemSet;
57 class G1RemSet;
58 class HeapRegionRemSetIterator;
59 class ConcurrentMark;
60 class ConcurrentMarkThread;
61 class ConcurrentG1Refine;
62 class GenerationCounters;
64 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
65 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
67 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
68 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70 enum GCAllocPurpose {
71 GCAllocForTenured,
72 GCAllocForSurvived,
73 GCAllocPurposeCount
74 };
76 class YoungList : public CHeapObj {
77 private:
78 G1CollectedHeap* _g1h;
80 HeapRegion* _head;
82 HeapRegion* _survivor_head;
83 HeapRegion* _survivor_tail;
85 HeapRegion* _curr;
87 size_t _length;
88 size_t _survivor_length;
90 size_t _last_sampled_rs_lengths;
91 size_t _sampled_rs_lengths;
93 void empty_list(HeapRegion* list);
95 public:
96 YoungList(G1CollectedHeap* g1h);
98 void push_region(HeapRegion* hr);
99 void add_survivor_region(HeapRegion* hr);
101 void empty_list();
102 bool is_empty() { return _length == 0; }
103 size_t length() { return _length; }
104 size_t survivor_length() { return _survivor_length; }
106 // Currently we do not keep track of the used byte sum for the
107 // young list and the survivors and it'd be quite a lot of work to
108 // do so. When we'll eventually replace the young list with
109 // instances of HeapRegionLinkedList we'll get that for free. So,
110 // we'll report the more accurate information then.
111 size_t eden_used_bytes() {
112 assert(length() >= survivor_length(), "invariant");
113 return (length() - survivor_length()) * HeapRegion::GrainBytes;
114 }
115 size_t survivor_used_bytes() {
116 return survivor_length() * HeapRegion::GrainBytes;
117 }
119 void rs_length_sampling_init();
120 bool rs_length_sampling_more();
121 void rs_length_sampling_next();
123 void reset_sampled_info() {
124 _last_sampled_rs_lengths = 0;
125 }
126 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128 // for development purposes
129 void reset_auxilary_lists();
130 void clear() { _head = NULL; _length = 0; }
132 void clear_survivors() {
133 _survivor_head = NULL;
134 _survivor_tail = NULL;
135 _survivor_length = 0;
136 }
138 HeapRegion* first_region() { return _head; }
139 HeapRegion* first_survivor_region() { return _survivor_head; }
140 HeapRegion* last_survivor_region() { return _survivor_tail; }
142 // debugging
143 bool check_list_well_formed();
144 bool check_list_empty(bool check_sample = true);
145 void print();
146 };
148 class MutatorAllocRegion : public G1AllocRegion {
149 protected:
150 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
151 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
152 public:
153 MutatorAllocRegion()
154 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
155 };
157 class RefineCardTableEntryClosure;
158 class G1CollectedHeap : public SharedHeap {
159 friend class VM_G1CollectForAllocation;
160 friend class VM_GenCollectForPermanentAllocation;
161 friend class VM_G1CollectFull;
162 friend class VM_G1IncCollectionPause;
163 friend class VMStructs;
164 friend class MutatorAllocRegion;
166 // Closures used in implementation.
167 friend class G1ParCopyHelper;
168 friend class G1IsAliveClosure;
169 friend class G1EvacuateFollowersClosure;
170 friend class G1ParScanThreadState;
171 friend class G1ParScanClosureSuper;
172 friend class G1ParEvacuateFollowersClosure;
173 friend class G1ParTask;
174 friend class G1FreeGarbageRegionClosure;
175 friend class RefineCardTableEntryClosure;
176 friend class G1PrepareCompactClosure;
177 friend class RegionSorter;
178 friend class RegionResetter;
179 friend class CountRCClosure;
180 friend class EvacPopObjClosure;
181 friend class G1ParCleanupCTTask;
183 // Other related classes.
184 friend class G1MarkSweep;
186 private:
187 // The one and only G1CollectedHeap, so static functions can find it.
188 static G1CollectedHeap* _g1h;
190 static size_t _humongous_object_threshold_in_words;
192 // Storage for the G1 heap (excludes the permanent generation).
193 VirtualSpace _g1_storage;
194 MemRegion _g1_reserved;
196 // The part of _g1_storage that is currently committed.
197 MemRegion _g1_committed;
199 // The master free list. It will satisfy all new region allocations.
200 MasterFreeRegionList _free_list;
202 // The secondary free list which contains regions that have been
203 // freed up during the cleanup process. This will be appended to the
204 // master free list when appropriate.
205 SecondaryFreeRegionList _secondary_free_list;
207 // It keeps track of the humongous regions.
208 MasterHumongousRegionSet _humongous_set;
210 // The number of regions we could create by expansion.
211 size_t _expansion_regions;
213 // The block offset table for the G1 heap.
214 G1BlockOffsetSharedArray* _bot_shared;
216 // Move all of the regions off the free lists, then rebuild those free
217 // lists, before and after full GC.
218 void tear_down_region_lists();
219 void rebuild_region_lists();
221 // The sequence of all heap regions in the heap.
222 HeapRegionSeq _hrs;
224 // Alloc region used to satisfy mutator allocation requests.
225 MutatorAllocRegion _mutator_alloc_region;
227 // It resets the mutator alloc region before new allocations can take place.
228 void init_mutator_alloc_region();
230 // It releases the mutator alloc region.
231 void release_mutator_alloc_region();
233 void abandon_gc_alloc_regions();
235 // The to-space memory regions into which objects are being copied during
236 // a GC.
237 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
238 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
239 // These are the regions, one per GCAllocPurpose, that are half-full
240 // at the end of a collection and that we want to reuse during the
241 // next collection.
242 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
243 // This specifies whether we will keep the last half-full region at
244 // the end of a collection so that it can be reused during the next
245 // collection (this is specified per GCAllocPurpose)
246 bool _retain_gc_alloc_region[GCAllocPurposeCount];
248 // A list of the regions that have been set to be alloc regions in the
249 // current collection.
250 HeapRegion* _gc_alloc_region_list;
252 // Helper for monitoring and management support.
253 G1MonitoringSupport* _g1mm;
255 // Determines PLAB size for a particular allocation purpose.
256 static size_t desired_plab_sz(GCAllocPurpose purpose);
258 // When called by par thread, requires the FreeList_lock to be held.
259 void push_gc_alloc_region(HeapRegion* hr);
261 // This should only be called single-threaded. Undeclares all GC alloc
262 // regions.
263 void forget_alloc_region_list();
265 // Should be used to set an alloc region, because there's other
266 // associated bookkeeping.
267 void set_gc_alloc_region(int purpose, HeapRegion* r);
269 // Check well-formedness of alloc region list.
270 bool check_gc_alloc_regions();
272 // Outside of GC pauses, the number of bytes used in all regions other
273 // than the current allocation region.
274 size_t _summary_bytes_used;
276 // This is used for a quick test on whether a reference points into
277 // the collection set or not. Basically, we have an array, with one
278 // byte per region, and that byte denotes whether the corresponding
279 // region is in the collection set or not. The entry corresponding
280 // the bottom of the heap, i.e., region 0, is pointed to by
281 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
282 // biased so that it actually points to address 0 of the address
283 // space, to make the test as fast as possible (we can simply shift
284 // the address to address into it, instead of having to subtract the
285 // bottom of the heap from the address before shifting it; basically
286 // it works in the same way the card table works).
287 bool* _in_cset_fast_test;
289 // The allocated array used for the fast test on whether a reference
290 // points into the collection set or not. This field is also used to
291 // free the array.
292 bool* _in_cset_fast_test_base;
294 // The length of the _in_cset_fast_test_base array.
295 size_t _in_cset_fast_test_length;
297 volatile unsigned _gc_time_stamp;
299 size_t* _surviving_young_words;
301 void setup_surviving_young_words();
302 void update_surviving_young_words(size_t* surv_young_words);
303 void cleanup_surviving_young_words();
305 // It decides whether an explicit GC should start a concurrent cycle
306 // instead of doing a STW GC. Currently, a concurrent cycle is
307 // explicitly started if:
308 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
309 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
310 bool should_do_concurrent_full_gc(GCCause::Cause cause);
312 // Keeps track of how many "full collections" (i.e., Full GCs or
313 // concurrent cycles) we have completed. The number of them we have
314 // started is maintained in _total_full_collections in CollectedHeap.
315 volatile unsigned int _full_collections_completed;
317 // This is a non-product method that is helpful for testing. It is
318 // called at the end of a GC and artificially expands the heap by
319 // allocating a number of dead regions. This way we can induce very
320 // frequent marking cycles and stress the cleanup / concurrent
321 // cleanup code more (as all the regions that will be allocated by
322 // this method will be found dead by the marking cycle).
323 void allocate_dummy_regions() PRODUCT_RETURN;
325 // These are macros so that, if the assert fires, we get the correct
326 // line number, file, etc.
328 #define heap_locking_asserts_err_msg(_extra_message_) \
329 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
330 (_extra_message_), \
331 BOOL_TO_STR(Heap_lock->owned_by_self()), \
332 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
333 BOOL_TO_STR(Thread::current()->is_VM_thread()))
335 #define assert_heap_locked() \
336 do { \
337 assert(Heap_lock->owned_by_self(), \
338 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
339 } while (0)
341 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
342 do { \
343 assert(Heap_lock->owned_by_self() || \
344 (SafepointSynchronize::is_at_safepoint() && \
345 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
346 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
347 "should be at a safepoint")); \
348 } while (0)
350 #define assert_heap_locked_and_not_at_safepoint() \
351 do { \
352 assert(Heap_lock->owned_by_self() && \
353 !SafepointSynchronize::is_at_safepoint(), \
354 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
355 "should not be at a safepoint")); \
356 } while (0)
358 #define assert_heap_not_locked() \
359 do { \
360 assert(!Heap_lock->owned_by_self(), \
361 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
362 } while (0)
364 #define assert_heap_not_locked_and_not_at_safepoint() \
365 do { \
366 assert(!Heap_lock->owned_by_self() && \
367 !SafepointSynchronize::is_at_safepoint(), \
368 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
369 "should not be at a safepoint")); \
370 } while (0)
372 #define assert_at_safepoint(_should_be_vm_thread_) \
373 do { \
374 assert(SafepointSynchronize::is_at_safepoint() && \
375 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
376 heap_locking_asserts_err_msg("should be at a safepoint")); \
377 } while (0)
379 #define assert_not_at_safepoint() \
380 do { \
381 assert(!SafepointSynchronize::is_at_safepoint(), \
382 heap_locking_asserts_err_msg("should not be at a safepoint")); \
383 } while (0)
385 protected:
387 // Returns "true" iff none of the gc alloc regions have any allocations
388 // since the last call to "save_marks".
389 bool all_alloc_regions_no_allocs_since_save_marks();
390 // Perform finalization stuff on all allocation regions.
391 void retire_all_alloc_regions();
393 // The number of regions allocated to hold humongous objects.
394 int _num_humongous_regions;
395 YoungList* _young_list;
397 // The current policy object for the collector.
398 G1CollectorPolicy* _g1_policy;
400 // This is the second level of trying to allocate a new region. If
401 // new_region() didn't find a region on the free_list, this call will
402 // check whether there's anything available on the
403 // secondary_free_list and/or wait for more regions to appear on
404 // that list, if _free_regions_coming is set.
405 HeapRegion* new_region_try_secondary_free_list();
407 // Try to allocate a single non-humongous HeapRegion sufficient for
408 // an allocation of the given word_size. If do_expand is true,
409 // attempt to expand the heap if necessary to satisfy the allocation
410 // request.
411 HeapRegion* new_region(size_t word_size, bool do_expand);
413 // Try to allocate a new region to be used for allocation by
414 // a GC thread. It will try to expand the heap if no region is
415 // available.
416 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
418 // Attempt to satisfy a humongous allocation request of the given
419 // size by finding a contiguous set of free regions of num_regions
420 // length and remove them from the master free list. Return the
421 // index of the first region or G1_NULL_HRS_INDEX if the search
422 // was unsuccessful.
423 size_t humongous_obj_allocate_find_first(size_t num_regions,
424 size_t word_size);
426 // Initialize a contiguous set of free regions of length num_regions
427 // and starting at index first so that they appear as a single
428 // humongous region.
429 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
430 size_t num_regions,
431 size_t word_size);
433 // Attempt to allocate a humongous object of the given size. Return
434 // NULL if unsuccessful.
435 HeapWord* humongous_obj_allocate(size_t word_size);
437 // The following two methods, allocate_new_tlab() and
438 // mem_allocate(), are the two main entry points from the runtime
439 // into the G1's allocation routines. They have the following
440 // assumptions:
441 //
442 // * They should both be called outside safepoints.
443 //
444 // * They should both be called without holding the Heap_lock.
445 //
446 // * All allocation requests for new TLABs should go to
447 // allocate_new_tlab().
448 //
449 // * All non-TLAB allocation requests should go to mem_allocate().
450 //
451 // * If either call cannot satisfy the allocation request using the
452 // current allocating region, they will try to get a new one. If
453 // this fails, they will attempt to do an evacuation pause and
454 // retry the allocation.
455 //
456 // * If all allocation attempts fail, even after trying to schedule
457 // an evacuation pause, allocate_new_tlab() will return NULL,
458 // whereas mem_allocate() will attempt a heap expansion and/or
459 // schedule a Full GC.
460 //
461 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
462 // should never be called with word_size being humongous. All
463 // humongous allocation requests should go to mem_allocate() which
464 // will satisfy them with a special path.
466 virtual HeapWord* allocate_new_tlab(size_t word_size);
468 virtual HeapWord* mem_allocate(size_t word_size,
469 bool* gc_overhead_limit_was_exceeded);
471 // The following three methods take a gc_count_before_ret
472 // parameter which is used to return the GC count if the method
473 // returns NULL. Given that we are required to read the GC count
474 // while holding the Heap_lock, and these paths will take the
475 // Heap_lock at some point, it's easier to get them to read the GC
476 // count while holding the Heap_lock before they return NULL instead
477 // of the caller (namely: mem_allocate()) having to also take the
478 // Heap_lock just to read the GC count.
480 // First-level mutator allocation attempt: try to allocate out of
481 // the mutator alloc region without taking the Heap_lock. This
482 // should only be used for non-humongous allocations.
483 inline HeapWord* attempt_allocation(size_t word_size,
484 unsigned int* gc_count_before_ret);
486 // Second-level mutator allocation attempt: take the Heap_lock and
487 // retry the allocation attempt, potentially scheduling a GC
488 // pause. This should only be used for non-humongous allocations.
489 HeapWord* attempt_allocation_slow(size_t word_size,
490 unsigned int* gc_count_before_ret);
492 // Takes the Heap_lock and attempts a humongous allocation. It can
493 // potentially schedule a GC pause.
494 HeapWord* attempt_allocation_humongous(size_t word_size,
495 unsigned int* gc_count_before_ret);
497 // Allocation attempt that should be called during safepoints (e.g.,
498 // at the end of a successful GC). expect_null_mutator_alloc_region
499 // specifies whether the mutator alloc region is expected to be NULL
500 // or not.
501 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
502 bool expect_null_mutator_alloc_region);
504 // It dirties the cards that cover the block so that so that the post
505 // write barrier never queues anything when updating objects on this
506 // block. It is assumed (and in fact we assert) that the block
507 // belongs to a young region.
508 inline void dirty_young_block(HeapWord* start, size_t word_size);
510 // Allocate blocks during garbage collection. Will ensure an
511 // allocation region, either by picking one or expanding the
512 // heap, and then allocate a block of the given size. The block
513 // may not be a humongous - it must fit into a single heap region.
514 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
516 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
517 HeapRegion* alloc_region,
518 bool par,
519 size_t word_size);
521 // Ensure that no further allocations can happen in "r", bearing in mind
522 // that parallel threads might be attempting allocations.
523 void par_allocate_remaining_space(HeapRegion* r);
525 // Retires an allocation region when it is full or at the end of a
526 // GC pause.
527 void retire_alloc_region(HeapRegion* alloc_region, bool par);
529 // These two methods are the "callbacks" from the G1AllocRegion class.
531 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
532 void retire_mutator_alloc_region(HeapRegion* alloc_region,
533 size_t allocated_bytes);
535 // - if explicit_gc is true, the GC is for a System.gc() or a heap
536 // inspection request and should collect the entire heap
537 // - if clear_all_soft_refs is true, all soft references should be
538 // cleared during the GC
539 // - if explicit_gc is false, word_size describes the allocation that
540 // the GC should attempt (at least) to satisfy
541 // - it returns false if it is unable to do the collection due to the
542 // GC locker being active, true otherwise
543 bool do_collection(bool explicit_gc,
544 bool clear_all_soft_refs,
545 size_t word_size);
547 // Callback from VM_G1CollectFull operation.
548 // Perform a full collection.
549 void do_full_collection(bool clear_all_soft_refs);
551 // Resize the heap if necessary after a full collection. If this is
552 // after a collect-for allocation, "word_size" is the allocation size,
553 // and will be considered part of the used portion of the heap.
554 void resize_if_necessary_after_full_collection(size_t word_size);
556 // Callback from VM_G1CollectForAllocation operation.
557 // This function does everything necessary/possible to satisfy a
558 // failed allocation request (including collection, expansion, etc.)
559 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
561 // Attempting to expand the heap sufficiently
562 // to support an allocation of the given "word_size". If
563 // successful, perform the allocation and return the address of the
564 // allocated block, or else "NULL".
565 HeapWord* expand_and_allocate(size_t word_size);
567 public:
569 G1MonitoringSupport* g1mm() { return _g1mm; }
571 // Expand the garbage-first heap by at least the given size (in bytes!).
572 // Returns true if the heap was expanded by the requested amount;
573 // false otherwise.
574 // (Rounds up to a HeapRegion boundary.)
575 bool expand(size_t expand_bytes);
577 // Do anything common to GC's.
578 virtual void gc_prologue(bool full);
579 virtual void gc_epilogue(bool full);
581 // We register a region with the fast "in collection set" test. We
582 // simply set to true the array slot corresponding to this region.
583 void register_region_with_in_cset_fast_test(HeapRegion* r) {
584 assert(_in_cset_fast_test_base != NULL, "sanity");
585 assert(r->in_collection_set(), "invariant");
586 size_t index = r->hrs_index();
587 assert(index < _in_cset_fast_test_length, "invariant");
588 assert(!_in_cset_fast_test_base[index], "invariant");
589 _in_cset_fast_test_base[index] = true;
590 }
592 // This is a fast test on whether a reference points into the
593 // collection set or not. It does not assume that the reference
594 // points into the heap; if it doesn't, it will return false.
595 bool in_cset_fast_test(oop obj) {
596 assert(_in_cset_fast_test != NULL, "sanity");
597 if (_g1_committed.contains((HeapWord*) obj)) {
598 // no need to subtract the bottom of the heap from obj,
599 // _in_cset_fast_test is biased
600 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
601 bool ret = _in_cset_fast_test[index];
602 // let's make sure the result is consistent with what the slower
603 // test returns
604 assert( ret || !obj_in_cs(obj), "sanity");
605 assert(!ret || obj_in_cs(obj), "sanity");
606 return ret;
607 } else {
608 return false;
609 }
610 }
612 void clear_cset_fast_test() {
613 assert(_in_cset_fast_test_base != NULL, "sanity");
614 memset(_in_cset_fast_test_base, false,
615 _in_cset_fast_test_length * sizeof(bool));
616 }
618 // This is called at the end of either a concurrent cycle or a Full
619 // GC to update the number of full collections completed. Those two
620 // can happen in a nested fashion, i.e., we start a concurrent
621 // cycle, a Full GC happens half-way through it which ends first,
622 // and then the cycle notices that a Full GC happened and ends
623 // too. The concurrent parameter is a boolean to help us do a bit
624 // tighter consistency checking in the method. If concurrent is
625 // false, the caller is the inner caller in the nesting (i.e., the
626 // Full GC). If concurrent is true, the caller is the outer caller
627 // in this nesting (i.e., the concurrent cycle). Further nesting is
628 // not currently supported. The end of the this call also notifies
629 // the FullGCCount_lock in case a Java thread is waiting for a full
630 // GC to happen (e.g., it called System.gc() with
631 // +ExplicitGCInvokesConcurrent).
632 void increment_full_collections_completed(bool concurrent);
634 unsigned int full_collections_completed() {
635 return _full_collections_completed;
636 }
638 protected:
640 // Shrink the garbage-first heap by at most the given size (in bytes!).
641 // (Rounds down to a HeapRegion boundary.)
642 virtual void shrink(size_t expand_bytes);
643 void shrink_helper(size_t expand_bytes);
645 #if TASKQUEUE_STATS
646 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
647 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
648 void reset_taskqueue_stats();
649 #endif // TASKQUEUE_STATS
651 // Schedule the VM operation that will do an evacuation pause to
652 // satisfy an allocation request of word_size. *succeeded will
653 // return whether the VM operation was successful (it did do an
654 // evacuation pause) or not (another thread beat us to it or the GC
655 // locker was active). Given that we should not be holding the
656 // Heap_lock when we enter this method, we will pass the
657 // gc_count_before (i.e., total_collections()) as a parameter since
658 // it has to be read while holding the Heap_lock. Currently, both
659 // methods that call do_collection_pause() release the Heap_lock
660 // before the call, so it's easy to read gc_count_before just before.
661 HeapWord* do_collection_pause(size_t word_size,
662 unsigned int gc_count_before,
663 bool* succeeded);
665 // The guts of the incremental collection pause, executed by the vm
666 // thread. It returns false if it is unable to do the collection due
667 // to the GC locker being active, true otherwise
668 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
670 // Actually do the work of evacuating the collection set.
671 void evacuate_collection_set();
673 // The g1 remembered set of the heap.
674 G1RemSet* _g1_rem_set;
675 // And it's mod ref barrier set, used to track updates for the above.
676 ModRefBarrierSet* _mr_bs;
678 // A set of cards that cover the objects for which the Rsets should be updated
679 // concurrently after the collection.
680 DirtyCardQueueSet _dirty_card_queue_set;
682 // The Heap Region Rem Set Iterator.
683 HeapRegionRemSetIterator** _rem_set_iterator;
685 // The closure used to refine a single card.
686 RefineCardTableEntryClosure* _refine_cte_cl;
688 // A function to check the consistency of dirty card logs.
689 void check_ct_logs_at_safepoint();
691 // A DirtyCardQueueSet that is used to hold cards that contain
692 // references into the current collection set. This is used to
693 // update the remembered sets of the regions in the collection
694 // set in the event of an evacuation failure.
695 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
697 // After a collection pause, make the regions in the CS into free
698 // regions.
699 void free_collection_set(HeapRegion* cs_head);
701 // Abandon the current collection set without recording policy
702 // statistics or updating free lists.
703 void abandon_collection_set(HeapRegion* cs_head);
705 // Applies "scan_non_heap_roots" to roots outside the heap,
706 // "scan_rs" to roots inside the heap (having done "set_region" to
707 // indicate the region in which the root resides), and does "scan_perm"
708 // (setting the generation to the perm generation.) If "scan_rs" is
709 // NULL, then this step is skipped. The "worker_i"
710 // param is for use with parallel roots processing, and should be
711 // the "i" of the calling parallel worker thread's work(i) function.
712 // In the sequential case this param will be ignored.
713 void g1_process_strong_roots(bool collecting_perm_gen,
714 SharedHeap::ScanningOption so,
715 OopClosure* scan_non_heap_roots,
716 OopsInHeapRegionClosure* scan_rs,
717 OopsInGenClosure* scan_perm,
718 int worker_i);
720 // Apply "blk" to all the weak roots of the system. These include
721 // JNI weak roots, the code cache, system dictionary, symbol table,
722 // string table, and referents of reachable weak refs.
723 void g1_process_weak_roots(OopClosure* root_closure,
724 OopClosure* non_root_closure);
726 // Invoke "save_marks" on all heap regions.
727 void save_marks();
729 // Frees a non-humongous region by initializing its contents and
730 // adding it to the free list that's passed as a parameter (this is
731 // usually a local list which will be appended to the master free
732 // list later). The used bytes of freed regions are accumulated in
733 // pre_used. If par is true, the region's RSet will not be freed
734 // up. The assumption is that this will be done later.
735 void free_region(HeapRegion* hr,
736 size_t* pre_used,
737 FreeRegionList* free_list,
738 bool par);
740 // Frees a humongous region by collapsing it into individual regions
741 // and calling free_region() for each of them. The freed regions
742 // will be added to the free list that's passed as a parameter (this
743 // is usually a local list which will be appended to the master free
744 // list later). The used bytes of freed regions are accumulated in
745 // pre_used. If par is true, the region's RSet will not be freed
746 // up. The assumption is that this will be done later.
747 void free_humongous_region(HeapRegion* hr,
748 size_t* pre_used,
749 FreeRegionList* free_list,
750 HumongousRegionSet* humongous_proxy_set,
751 bool par);
753 // Notifies all the necessary spaces that the committed space has
754 // been updated (either expanded or shrunk). It should be called
755 // after _g1_storage is updated.
756 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
758 // The concurrent marker (and the thread it runs in.)
759 ConcurrentMark* _cm;
760 ConcurrentMarkThread* _cmThread;
761 bool _mark_in_progress;
763 // The concurrent refiner.
764 ConcurrentG1Refine* _cg1r;
766 // The parallel task queues
767 RefToScanQueueSet *_task_queues;
769 // True iff a evacuation has failed in the current collection.
770 bool _evacuation_failed;
772 // Set the attribute indicating whether evacuation has failed in the
773 // current collection.
774 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
776 // Failed evacuations cause some logical from-space objects to have
777 // forwarding pointers to themselves. Reset them.
778 void remove_self_forwarding_pointers();
780 // When one is non-null, so is the other. Together, they each pair is
781 // an object with a preserved mark, and its mark value.
782 GrowableArray<oop>* _objs_with_preserved_marks;
783 GrowableArray<markOop>* _preserved_marks_of_objs;
785 // Preserve the mark of "obj", if necessary, in preparation for its mark
786 // word being overwritten with a self-forwarding-pointer.
787 void preserve_mark_if_necessary(oop obj, markOop m);
789 // The stack of evac-failure objects left to be scanned.
790 GrowableArray<oop>* _evac_failure_scan_stack;
791 // The closure to apply to evac-failure objects.
793 OopsInHeapRegionClosure* _evac_failure_closure;
794 // Set the field above.
795 void
796 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
797 _evac_failure_closure = evac_failure_closure;
798 }
800 // Push "obj" on the scan stack.
801 void push_on_evac_failure_scan_stack(oop obj);
802 // Process scan stack entries until the stack is empty.
803 void drain_evac_failure_scan_stack();
804 // True iff an invocation of "drain_scan_stack" is in progress; to
805 // prevent unnecessary recursion.
806 bool _drain_in_progress;
808 // Do any necessary initialization for evacuation-failure handling.
809 // "cl" is the closure that will be used to process evac-failure
810 // objects.
811 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
812 // Do any necessary cleanup for evacuation-failure handling data
813 // structures.
814 void finalize_for_evac_failure();
816 // An attempt to evacuate "obj" has failed; take necessary steps.
817 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
818 void handle_evacuation_failure_common(oop obj, markOop m);
820 // Ensure that the relevant gc_alloc regions are set.
821 void get_gc_alloc_regions();
822 // We're done with GC alloc regions. We are going to tear down the
823 // gc alloc list and remove the gc alloc tag from all the regions on
824 // that list. However, we will also retain the last (i.e., the one
825 // that is half-full) GC alloc region, per GCAllocPurpose, for
826 // possible reuse during the next collection, provided
827 // _retain_gc_alloc_region[] indicates that it should be the
828 // case. Said regions are kept in the _retained_gc_alloc_regions[]
829 // array. If the parameter totally is set, we will not retain any
830 // regions, irrespective of what _retain_gc_alloc_region[]
831 // indicates.
832 void release_gc_alloc_regions(bool totally);
833 #ifndef PRODUCT
834 // Useful for debugging.
835 void print_gc_alloc_regions();
836 #endif // !PRODUCT
838 // Instance of the concurrent mark is_alive closure for embedding
839 // into the reference processor as the is_alive_non_header. This
840 // prevents unnecessary additions to the discovered lists during
841 // concurrent discovery.
842 G1CMIsAliveClosure _is_alive_closure;
844 // ("Weak") Reference processing support
845 ReferenceProcessor* _ref_processor;
847 enum G1H_process_strong_roots_tasks {
848 G1H_PS_mark_stack_oops_do,
849 G1H_PS_refProcessor_oops_do,
850 // Leave this one last.
851 G1H_PS_NumElements
852 };
854 SubTasksDone* _process_strong_tasks;
856 volatile bool _free_regions_coming;
858 public:
860 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
862 void set_refine_cte_cl_concurrency(bool concurrent);
864 RefToScanQueue *task_queue(int i) const;
866 // A set of cards where updates happened during the GC
867 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
869 // A DirtyCardQueueSet that is used to hold cards that contain
870 // references into the current collection set. This is used to
871 // update the remembered sets of the regions in the collection
872 // set in the event of an evacuation failure.
873 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
874 { return _into_cset_dirty_card_queue_set; }
876 // Create a G1CollectedHeap with the specified policy.
877 // Must call the initialize method afterwards.
878 // May not return if something goes wrong.
879 G1CollectedHeap(G1CollectorPolicy* policy);
881 // Initialize the G1CollectedHeap to have the initial and
882 // maximum sizes, permanent generation, and remembered and barrier sets
883 // specified by the policy object.
884 jint initialize();
886 virtual void ref_processing_init();
888 void set_par_threads(int t) {
889 SharedHeap::set_par_threads(t);
890 _process_strong_tasks->set_n_threads(t);
891 }
893 virtual CollectedHeap::Name kind() const {
894 return CollectedHeap::G1CollectedHeap;
895 }
897 // The current policy object for the collector.
898 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
900 // Adaptive size policy. No such thing for g1.
901 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
903 // The rem set and barrier set.
904 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
905 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
907 // The rem set iterator.
908 HeapRegionRemSetIterator* rem_set_iterator(int i) {
909 return _rem_set_iterator[i];
910 }
912 HeapRegionRemSetIterator* rem_set_iterator() {
913 return _rem_set_iterator[0];
914 }
916 unsigned get_gc_time_stamp() {
917 return _gc_time_stamp;
918 }
920 void reset_gc_time_stamp() {
921 _gc_time_stamp = 0;
922 OrderAccess::fence();
923 }
925 void increment_gc_time_stamp() {
926 ++_gc_time_stamp;
927 OrderAccess::fence();
928 }
930 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
931 DirtyCardQueue* into_cset_dcq,
932 bool concurrent, int worker_i);
934 // The shared block offset table array.
935 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
937 // Reference Processing accessor
938 ReferenceProcessor* ref_processor() { return _ref_processor; }
940 virtual size_t capacity() const;
941 virtual size_t used() const;
942 // This should be called when we're not holding the heap lock. The
943 // result might be a bit inaccurate.
944 size_t used_unlocked() const;
945 size_t recalculate_used() const;
946 #ifndef PRODUCT
947 size_t recalculate_used_regions() const;
948 #endif // PRODUCT
950 // These virtual functions do the actual allocation.
951 // Some heaps may offer a contiguous region for shared non-blocking
952 // allocation, via inlined code (by exporting the address of the top and
953 // end fields defining the extent of the contiguous allocation region.)
954 // But G1CollectedHeap doesn't yet support this.
956 // Return an estimate of the maximum allocation that could be performed
957 // without triggering any collection or expansion activity. In a
958 // generational collector, for example, this is probably the largest
959 // allocation that could be supported (without expansion) in the youngest
960 // generation. It is "unsafe" because no locks are taken; the result
961 // should be treated as an approximation, not a guarantee, for use in
962 // heuristic resizing decisions.
963 virtual size_t unsafe_max_alloc();
965 virtual bool is_maximal_no_gc() const {
966 return _g1_storage.uncommitted_size() == 0;
967 }
969 // The total number of regions in the heap.
970 size_t n_regions() { return _hrs.length(); }
972 // The max number of regions in the heap.
973 size_t max_regions() { return _hrs.max_length(); }
975 // The number of regions that are completely free.
976 size_t free_regions() { return _free_list.length(); }
978 // The number of regions that are not completely free.
979 size_t used_regions() { return n_regions() - free_regions(); }
981 // The number of regions available for "regular" expansion.
982 size_t expansion_regions() { return _expansion_regions; }
984 // Factory method for HeapRegion instances. It will return NULL if
985 // the allocation fails.
986 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
988 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
989 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
990 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
991 void verify_dirty_young_regions() PRODUCT_RETURN;
993 // verify_region_sets() performs verification over the region
994 // lists. It will be compiled in the product code to be used when
995 // necessary (i.e., during heap verification).
996 void verify_region_sets();
998 // verify_region_sets_optional() is planted in the code for
999 // list verification in non-product builds (and it can be enabled in
1000 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1001 #if HEAP_REGION_SET_FORCE_VERIFY
1002 void verify_region_sets_optional() {
1003 verify_region_sets();
1004 }
1005 #else // HEAP_REGION_SET_FORCE_VERIFY
1006 void verify_region_sets_optional() { }
1007 #endif // HEAP_REGION_SET_FORCE_VERIFY
1009 #ifdef ASSERT
1010 bool is_on_master_free_list(HeapRegion* hr) {
1011 return hr->containing_set() == &_free_list;
1012 }
1014 bool is_in_humongous_set(HeapRegion* hr) {
1015 return hr->containing_set() == &_humongous_set;
1016 }
1017 #endif // ASSERT
1019 // Wrapper for the region list operations that can be called from
1020 // methods outside this class.
1022 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1023 _secondary_free_list.add_as_tail(list);
1024 }
1026 void append_secondary_free_list() {
1027 _free_list.add_as_head(&_secondary_free_list);
1028 }
1030 void append_secondary_free_list_if_not_empty_with_lock() {
1031 // If the secondary free list looks empty there's no reason to
1032 // take the lock and then try to append it.
1033 if (!_secondary_free_list.is_empty()) {
1034 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1035 append_secondary_free_list();
1036 }
1037 }
1039 void set_free_regions_coming();
1040 void reset_free_regions_coming();
1041 bool free_regions_coming() { return _free_regions_coming; }
1042 void wait_while_free_regions_coming();
1044 // Perform a collection of the heap; intended for use in implementing
1045 // "System.gc". This probably implies as full a collection as the
1046 // "CollectedHeap" supports.
1047 virtual void collect(GCCause::Cause cause);
1049 // The same as above but assume that the caller holds the Heap_lock.
1050 void collect_locked(GCCause::Cause cause);
1052 // This interface assumes that it's being called by the
1053 // vm thread. It collects the heap assuming that the
1054 // heap lock is already held and that we are executing in
1055 // the context of the vm thread.
1056 virtual void collect_as_vm_thread(GCCause::Cause cause);
1058 // True iff a evacuation has failed in the most-recent collection.
1059 bool evacuation_failed() { return _evacuation_failed; }
1061 // It will free a region if it has allocated objects in it that are
1062 // all dead. It calls either free_region() or
1063 // free_humongous_region() depending on the type of the region that
1064 // is passed to it.
1065 void free_region_if_empty(HeapRegion* hr,
1066 size_t* pre_used,
1067 FreeRegionList* free_list,
1068 HumongousRegionSet* humongous_proxy_set,
1069 HRRSCleanupTask* hrrs_cleanup_task,
1070 bool par);
1072 // It appends the free list to the master free list and updates the
1073 // master humongous list according to the contents of the proxy
1074 // list. It also adjusts the total used bytes according to pre_used
1075 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1076 void update_sets_after_freeing_regions(size_t pre_used,
1077 FreeRegionList* free_list,
1078 HumongousRegionSet* humongous_proxy_set,
1079 bool par);
1081 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1082 virtual bool is_in(const void* p) const;
1084 // Return "TRUE" iff the given object address is within the collection
1085 // set.
1086 inline bool obj_in_cs(oop obj);
1088 // Return "TRUE" iff the given object address is in the reserved
1089 // region of g1 (excluding the permanent generation).
1090 bool is_in_g1_reserved(const void* p) const {
1091 return _g1_reserved.contains(p);
1092 }
1094 // Returns a MemRegion that corresponds to the space that has been
1095 // reserved for the heap
1096 MemRegion g1_reserved() {
1097 return _g1_reserved;
1098 }
1100 // Returns a MemRegion that corresponds to the space that has been
1101 // committed in the heap
1102 MemRegion g1_committed() {
1103 return _g1_committed;
1104 }
1106 virtual bool is_in_closed_subset(const void* p) const;
1108 // Dirty card table entries covering a list of young regions.
1109 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1111 // This resets the card table to all zeros. It is used after
1112 // a collection pause which used the card table to claim cards.
1113 void cleanUpCardTable();
1115 // Iteration functions.
1117 // Iterate over all the ref-containing fields of all objects, calling
1118 // "cl.do_oop" on each.
1119 virtual void oop_iterate(OopClosure* cl) {
1120 oop_iterate(cl, true);
1121 }
1122 void oop_iterate(OopClosure* cl, bool do_perm);
1124 // Same as above, restricted to a memory region.
1125 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1126 oop_iterate(mr, cl, true);
1127 }
1128 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1130 // Iterate over all objects, calling "cl.do_object" on each.
1131 virtual void object_iterate(ObjectClosure* cl) {
1132 object_iterate(cl, true);
1133 }
1134 virtual void safe_object_iterate(ObjectClosure* cl) {
1135 object_iterate(cl, true);
1136 }
1137 void object_iterate(ObjectClosure* cl, bool do_perm);
1139 // Iterate over all objects allocated since the last collection, calling
1140 // "cl.do_object" on each. The heap must have been initialized properly
1141 // to support this function, or else this call will fail.
1142 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1144 // Iterate over all spaces in use in the heap, in ascending address order.
1145 virtual void space_iterate(SpaceClosure* cl);
1147 // Iterate over heap regions, in address order, terminating the
1148 // iteration early if the "doHeapRegion" method returns "true".
1149 void heap_region_iterate(HeapRegionClosure* blk) const;
1151 // Iterate over heap regions starting with r (or the first region if "r"
1152 // is NULL), in address order, terminating early if the "doHeapRegion"
1153 // method returns "true".
1154 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1156 // Return the region with the given index. It assumes the index is valid.
1157 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1159 // Divide the heap region sequence into "chunks" of some size (the number
1160 // of regions divided by the number of parallel threads times some
1161 // overpartition factor, currently 4). Assumes that this will be called
1162 // in parallel by ParallelGCThreads worker threads with discinct worker
1163 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1164 // calls will use the same "claim_value", and that that claim value is
1165 // different from the claim_value of any heap region before the start of
1166 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1167 // attempting to claim the first region in each chunk, and, if
1168 // successful, applying the closure to each region in the chunk (and
1169 // setting the claim value of the second and subsequent regions of the
1170 // chunk.) For now requires that "doHeapRegion" always returns "false",
1171 // i.e., that a closure never attempt to abort a traversal.
1172 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1173 int worker,
1174 jint claim_value);
1176 // It resets all the region claim values to the default.
1177 void reset_heap_region_claim_values();
1179 #ifdef ASSERT
1180 bool check_heap_region_claim_values(jint claim_value);
1181 #endif // ASSERT
1183 // Iterate over the regions (if any) in the current collection set.
1184 void collection_set_iterate(HeapRegionClosure* blk);
1186 // As above but starting from region r
1187 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1189 // Returns the first (lowest address) compactible space in the heap.
1190 virtual CompactibleSpace* first_compactible_space();
1192 // A CollectedHeap will contain some number of spaces. This finds the
1193 // space containing a given address, or else returns NULL.
1194 virtual Space* space_containing(const void* addr) const;
1196 // A G1CollectedHeap will contain some number of heap regions. This
1197 // finds the region containing a given address, or else returns NULL.
1198 template <class T>
1199 inline HeapRegion* heap_region_containing(const T addr) const;
1201 // Like the above, but requires "addr" to be in the heap (to avoid a
1202 // null-check), and unlike the above, may return an continuing humongous
1203 // region.
1204 template <class T>
1205 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1207 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1208 // each address in the (reserved) heap is a member of exactly
1209 // one block. The defining characteristic of a block is that it is
1210 // possible to find its size, and thus to progress forward to the next
1211 // block. (Blocks may be of different sizes.) Thus, blocks may
1212 // represent Java objects, or they might be free blocks in a
1213 // free-list-based heap (or subheap), as long as the two kinds are
1214 // distinguishable and the size of each is determinable.
1216 // Returns the address of the start of the "block" that contains the
1217 // address "addr". We say "blocks" instead of "object" since some heaps
1218 // may not pack objects densely; a chunk may either be an object or a
1219 // non-object.
1220 virtual HeapWord* block_start(const void* addr) const;
1222 // Requires "addr" to be the start of a chunk, and returns its size.
1223 // "addr + size" is required to be the start of a new chunk, or the end
1224 // of the active area of the heap.
1225 virtual size_t block_size(const HeapWord* addr) const;
1227 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1228 // the block is an object.
1229 virtual bool block_is_obj(const HeapWord* addr) const;
1231 // Does this heap support heap inspection? (+PrintClassHistogram)
1232 virtual bool supports_heap_inspection() const { return true; }
1234 // Section on thread-local allocation buffers (TLABs)
1235 // See CollectedHeap for semantics.
1237 virtual bool supports_tlab_allocation() const;
1238 virtual size_t tlab_capacity(Thread* thr) const;
1239 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1241 // Can a compiler initialize a new object without store barriers?
1242 // This permission only extends from the creation of a new object
1243 // via a TLAB up to the first subsequent safepoint. If such permission
1244 // is granted for this heap type, the compiler promises to call
1245 // defer_store_barrier() below on any slow path allocation of
1246 // a new object for which such initializing store barriers will
1247 // have been elided. G1, like CMS, allows this, but should be
1248 // ready to provide a compensating write barrier as necessary
1249 // if that storage came out of a non-young region. The efficiency
1250 // of this implementation depends crucially on being able to
1251 // answer very efficiently in constant time whether a piece of
1252 // storage in the heap comes from a young region or not.
1253 // See ReduceInitialCardMarks.
1254 virtual bool can_elide_tlab_store_barriers() const {
1255 // 6920090: Temporarily disabled, because of lingering
1256 // instabilities related to RICM with G1. In the
1257 // interim, the option ReduceInitialCardMarksForG1
1258 // below is left solely as a debugging device at least
1259 // until 6920109 fixes the instabilities.
1260 return ReduceInitialCardMarksForG1;
1261 }
1263 virtual bool card_mark_must_follow_store() const {
1264 return true;
1265 }
1267 bool is_in_young(const oop obj) {
1268 HeapRegion* hr = heap_region_containing(obj);
1269 return hr != NULL && hr->is_young();
1270 }
1272 #ifdef ASSERT
1273 virtual bool is_in_partial_collection(const void* p);
1274 #endif
1276 virtual bool is_scavengable(const void* addr);
1278 // We don't need barriers for initializing stores to objects
1279 // in the young gen: for the SATB pre-barrier, there is no
1280 // pre-value that needs to be remembered; for the remembered-set
1281 // update logging post-barrier, we don't maintain remembered set
1282 // information for young gen objects. Note that non-generational
1283 // G1 does not have any "young" objects, should not elide
1284 // the rs logging barrier and so should always answer false below.
1285 // However, non-generational G1 (-XX:-G1Gen) appears to have
1286 // bit-rotted so was not tested below.
1287 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1288 // Re 6920090, 6920109 above.
1289 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1290 assert(G1Gen || !is_in_young(new_obj),
1291 "Non-generational G1 should never return true below");
1292 return is_in_young(new_obj);
1293 }
1295 // Can a compiler elide a store barrier when it writes
1296 // a permanent oop into the heap? Applies when the compiler
1297 // is storing x to the heap, where x->is_perm() is true.
1298 virtual bool can_elide_permanent_oop_store_barriers() const {
1299 // At least until perm gen collection is also G1-ified, at
1300 // which point this should return false.
1301 return true;
1302 }
1304 // Returns "true" iff the given word_size is "very large".
1305 static bool isHumongous(size_t word_size) {
1306 // Note this has to be strictly greater-than as the TLABs
1307 // are capped at the humongous thresold and we want to
1308 // ensure that we don't try to allocate a TLAB as
1309 // humongous and that we don't allocate a humongous
1310 // object in a TLAB.
1311 return word_size > _humongous_object_threshold_in_words;
1312 }
1314 // Update mod union table with the set of dirty cards.
1315 void updateModUnion();
1317 // Set the mod union bits corresponding to the given memRegion. Note
1318 // that this is always a safe operation, since it doesn't clear any
1319 // bits.
1320 void markModUnionRange(MemRegion mr);
1322 // Records the fact that a marking phase is no longer in progress.
1323 void set_marking_complete() {
1324 _mark_in_progress = false;
1325 }
1326 void set_marking_started() {
1327 _mark_in_progress = true;
1328 }
1329 bool mark_in_progress() {
1330 return _mark_in_progress;
1331 }
1333 // Print the maximum heap capacity.
1334 virtual size_t max_capacity() const;
1336 virtual jlong millis_since_last_gc();
1338 // Perform any cleanup actions necessary before allowing a verification.
1339 virtual void prepare_for_verify();
1341 // Perform verification.
1343 // vo == UsePrevMarking -> use "prev" marking information,
1344 // vo == UseNextMarking -> use "next" marking information
1345 // vo == UseMarkWord -> use the mark word in the object header
1346 //
1347 // NOTE: Only the "prev" marking information is guaranteed to be
1348 // consistent most of the time, so most calls to this should use
1349 // vo == UsePrevMarking.
1350 // Currently, there is only one case where this is called with
1351 // vo == UseNextMarking, which is to verify the "next" marking
1352 // information at the end of remark.
1353 // Currently there is only one place where this is called with
1354 // vo == UseMarkWord, which is to verify the marking during a
1355 // full GC.
1356 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1358 // Override; it uses the "prev" marking information
1359 virtual void verify(bool allow_dirty, bool silent);
1360 // Default behavior by calling print(tty);
1361 virtual void print() const;
1362 // This calls print_on(st, PrintHeapAtGCExtended).
1363 virtual void print_on(outputStream* st) const;
1364 // If extended is true, it will print out information for all
1365 // regions in the heap by calling print_on_extended(st).
1366 virtual void print_on(outputStream* st, bool extended) const;
1367 virtual void print_on_extended(outputStream* st) const;
1369 virtual void print_gc_threads_on(outputStream* st) const;
1370 virtual void gc_threads_do(ThreadClosure* tc) const;
1372 // Override
1373 void print_tracing_info() const;
1375 // The following two methods are helpful for debugging RSet issues.
1376 void print_cset_rsets() PRODUCT_RETURN;
1377 void print_all_rsets() PRODUCT_RETURN;
1379 // Convenience function to be used in situations where the heap type can be
1380 // asserted to be this type.
1381 static G1CollectedHeap* heap();
1383 void empty_young_list();
1385 void set_region_short_lived_locked(HeapRegion* hr);
1386 // add appropriate methods for any other surv rate groups
1388 YoungList* young_list() { return _young_list; }
1390 // debugging
1391 bool check_young_list_well_formed() {
1392 return _young_list->check_list_well_formed();
1393 }
1395 bool check_young_list_empty(bool check_heap,
1396 bool check_sample = true);
1398 // *** Stuff related to concurrent marking. It's not clear to me that so
1399 // many of these need to be public.
1401 // The functions below are helper functions that a subclass of
1402 // "CollectedHeap" can use in the implementation of its virtual
1403 // functions.
1404 // This performs a concurrent marking of the live objects in a
1405 // bitmap off to the side.
1406 void doConcurrentMark();
1408 // Do a full concurrent marking, synchronously.
1409 void do_sync_mark();
1411 bool isMarkedPrev(oop obj) const;
1412 bool isMarkedNext(oop obj) const;
1414 // vo == UsePrevMarking -> use "prev" marking information,
1415 // vo == UseNextMarking -> use "next" marking information,
1416 // vo == UseMarkWord -> use mark word from object header
1417 bool is_obj_dead_cond(const oop obj,
1418 const HeapRegion* hr,
1419 const VerifyOption vo) const {
1421 switch (vo) {
1422 case VerifyOption_G1UsePrevMarking:
1423 return is_obj_dead(obj, hr);
1424 case VerifyOption_G1UseNextMarking:
1425 return is_obj_ill(obj, hr);
1426 default:
1427 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1428 return !obj->is_gc_marked();
1429 }
1430 }
1432 // Determine if an object is dead, given the object and also
1433 // the region to which the object belongs. An object is dead
1434 // iff a) it was not allocated since the last mark and b) it
1435 // is not marked.
1437 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1438 return
1439 !hr->obj_allocated_since_prev_marking(obj) &&
1440 !isMarkedPrev(obj);
1441 }
1443 // This is used when copying an object to survivor space.
1444 // If the object is marked live, then we mark the copy live.
1445 // If the object is allocated since the start of this mark
1446 // cycle, then we mark the copy live.
1447 // If the object has been around since the previous mark
1448 // phase, and hasn't been marked yet during this phase,
1449 // then we don't mark it, we just wait for the
1450 // current marking cycle to get to it.
1452 // This function returns true when an object has been
1453 // around since the previous marking and hasn't yet
1454 // been marked during this marking.
1456 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1457 return
1458 !hr->obj_allocated_since_next_marking(obj) &&
1459 !isMarkedNext(obj);
1460 }
1462 // Determine if an object is dead, given only the object itself.
1463 // This will find the region to which the object belongs and
1464 // then call the region version of the same function.
1466 // Added if it is in permanent gen it isn't dead.
1467 // Added if it is NULL it isn't dead.
1469 // vo == UsePrevMarking -> use "prev" marking information,
1470 // vo == UseNextMarking -> use "next" marking information,
1471 // vo == UseMarkWord -> use mark word from object header
1472 bool is_obj_dead_cond(const oop obj,
1473 const VerifyOption vo) const {
1475 switch (vo) {
1476 case VerifyOption_G1UsePrevMarking:
1477 return is_obj_dead(obj);
1478 case VerifyOption_G1UseNextMarking:
1479 return is_obj_ill(obj);
1480 default:
1481 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1482 return !obj->is_gc_marked();
1483 }
1484 }
1486 bool is_obj_dead(const oop obj) const {
1487 const HeapRegion* hr = heap_region_containing(obj);
1488 if (hr == NULL) {
1489 if (Universe::heap()->is_in_permanent(obj))
1490 return false;
1491 else if (obj == NULL) return false;
1492 else return true;
1493 }
1494 else return is_obj_dead(obj, hr);
1495 }
1497 bool is_obj_ill(const oop obj) const {
1498 const HeapRegion* hr = heap_region_containing(obj);
1499 if (hr == NULL) {
1500 if (Universe::heap()->is_in_permanent(obj))
1501 return false;
1502 else if (obj == NULL) return false;
1503 else return true;
1504 }
1505 else return is_obj_ill(obj, hr);
1506 }
1508 // The following is just to alert the verification code
1509 // that a full collection has occurred and that the
1510 // remembered sets are no longer up to date.
1511 bool _full_collection;
1512 void set_full_collection() { _full_collection = true;}
1513 void clear_full_collection() {_full_collection = false;}
1514 bool full_collection() {return _full_collection;}
1516 ConcurrentMark* concurrent_mark() const { return _cm; }
1517 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1519 // The dirty cards region list is used to record a subset of regions
1520 // whose cards need clearing. The list if populated during the
1521 // remembered set scanning and drained during the card table
1522 // cleanup. Although the methods are reentrant, population/draining
1523 // phases must not overlap. For synchronization purposes the last
1524 // element on the list points to itself.
1525 HeapRegion* _dirty_cards_region_list;
1526 void push_dirty_cards_region(HeapRegion* hr);
1527 HeapRegion* pop_dirty_cards_region();
1529 public:
1530 void stop_conc_gc_threads();
1532 // <NEW PREDICTION>
1534 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1535 void check_if_region_is_too_expensive(double predicted_time_ms);
1536 size_t pending_card_num();
1537 size_t max_pending_card_num();
1538 size_t cards_scanned();
1540 // </NEW PREDICTION>
1542 protected:
1543 size_t _max_heap_capacity;
1544 };
1546 #define use_local_bitmaps 1
1547 #define verify_local_bitmaps 0
1548 #define oop_buffer_length 256
1550 #ifndef PRODUCT
1551 class GCLabBitMap;
1552 class GCLabBitMapClosure: public BitMapClosure {
1553 private:
1554 ConcurrentMark* _cm;
1555 GCLabBitMap* _bitmap;
1557 public:
1558 GCLabBitMapClosure(ConcurrentMark* cm,
1559 GCLabBitMap* bitmap) {
1560 _cm = cm;
1561 _bitmap = bitmap;
1562 }
1564 virtual bool do_bit(size_t offset);
1565 };
1566 #endif // !PRODUCT
1568 class GCLabBitMap: public BitMap {
1569 private:
1570 ConcurrentMark* _cm;
1572 int _shifter;
1573 size_t _bitmap_word_covers_words;
1575 // beginning of the heap
1576 HeapWord* _heap_start;
1578 // this is the actual start of the GCLab
1579 HeapWord* _real_start_word;
1581 // this is the actual end of the GCLab
1582 HeapWord* _real_end_word;
1584 // this is the first word, possibly located before the actual start
1585 // of the GCLab, that corresponds to the first bit of the bitmap
1586 HeapWord* _start_word;
1588 // size of a GCLab in words
1589 size_t _gclab_word_size;
1591 static int shifter() {
1592 return MinObjAlignment - 1;
1593 }
1595 // how many heap words does a single bitmap word corresponds to?
1596 static size_t bitmap_word_covers_words() {
1597 return BitsPerWord << shifter();
1598 }
1600 size_t gclab_word_size() const {
1601 return _gclab_word_size;
1602 }
1604 // Calculates actual GCLab size in words
1605 size_t gclab_real_word_size() const {
1606 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1607 / BitsPerWord;
1608 }
1610 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1611 size_t bits_in_bitmap = gclab_word_size >> shifter();
1612 // We are going to ensure that the beginning of a word in this
1613 // bitmap also corresponds to the beginning of a word in the
1614 // global marking bitmap. To handle the case where a GCLab
1615 // starts from the middle of the bitmap, we need to add enough
1616 // space (i.e. up to a bitmap word) to ensure that we have
1617 // enough bits in the bitmap.
1618 return bits_in_bitmap + BitsPerWord - 1;
1619 }
1620 public:
1621 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1622 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1623 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1624 _shifter(shifter()),
1625 _bitmap_word_covers_words(bitmap_word_covers_words()),
1626 _heap_start(heap_start),
1627 _gclab_word_size(gclab_word_size),
1628 _real_start_word(NULL),
1629 _real_end_word(NULL),
1630 _start_word(NULL)
1631 {
1632 guarantee( size_in_words() >= bitmap_size_in_words(),
1633 "just making sure");
1634 }
1636 inline unsigned heapWordToOffset(HeapWord* addr) {
1637 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1638 assert(offset < size(), "offset should be within bounds");
1639 return offset;
1640 }
1642 inline HeapWord* offsetToHeapWord(size_t offset) {
1643 HeapWord* addr = _start_word + (offset << _shifter);
1644 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1645 return addr;
1646 }
1648 bool fields_well_formed() {
1649 bool ret1 = (_real_start_word == NULL) &&
1650 (_real_end_word == NULL) &&
1651 (_start_word == NULL);
1652 if (ret1)
1653 return true;
1655 bool ret2 = _real_start_word >= _start_word &&
1656 _start_word < _real_end_word &&
1657 (_real_start_word + _gclab_word_size) == _real_end_word &&
1658 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1659 > _real_end_word;
1660 return ret2;
1661 }
1663 inline bool mark(HeapWord* addr) {
1664 guarantee(use_local_bitmaps, "invariant");
1665 assert(fields_well_formed(), "invariant");
1667 if (addr >= _real_start_word && addr < _real_end_word) {
1668 assert(!isMarked(addr), "should not have already been marked");
1670 // first mark it on the bitmap
1671 at_put(heapWordToOffset(addr), true);
1673 return true;
1674 } else {
1675 return false;
1676 }
1677 }
1679 inline bool isMarked(HeapWord* addr) {
1680 guarantee(use_local_bitmaps, "invariant");
1681 assert(fields_well_formed(), "invariant");
1683 return at(heapWordToOffset(addr));
1684 }
1686 void set_buffer(HeapWord* start) {
1687 guarantee(use_local_bitmaps, "invariant");
1688 clear();
1690 assert(start != NULL, "invariant");
1691 _real_start_word = start;
1692 _real_end_word = start + _gclab_word_size;
1694 size_t diff =
1695 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1696 _start_word = start - diff;
1698 assert(fields_well_formed(), "invariant");
1699 }
1701 #ifndef PRODUCT
1702 void verify() {
1703 // verify that the marks have been propagated
1704 GCLabBitMapClosure cl(_cm, this);
1705 iterate(&cl);
1706 }
1707 #endif // PRODUCT
1709 void retire() {
1710 guarantee(use_local_bitmaps, "invariant");
1711 assert(fields_well_formed(), "invariant");
1713 if (_start_word != NULL) {
1714 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1716 // this means that the bitmap was set up for the GCLab
1717 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1719 mark_bitmap->mostly_disjoint_range_union(this,
1720 0, // always start from the start of the bitmap
1721 _start_word,
1722 gclab_real_word_size());
1723 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1725 #ifndef PRODUCT
1726 if (use_local_bitmaps && verify_local_bitmaps)
1727 verify();
1728 #endif // PRODUCT
1729 } else {
1730 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1731 }
1732 }
1734 size_t bitmap_size_in_words() const {
1735 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1736 }
1738 };
1740 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1741 private:
1742 bool _retired;
1743 bool _during_marking;
1744 GCLabBitMap _bitmap;
1746 public:
1747 G1ParGCAllocBuffer(size_t gclab_word_size) :
1748 ParGCAllocBuffer(gclab_word_size),
1749 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1750 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1751 _retired(false)
1752 { }
1754 inline bool mark(HeapWord* addr) {
1755 guarantee(use_local_bitmaps, "invariant");
1756 assert(_during_marking, "invariant");
1757 return _bitmap.mark(addr);
1758 }
1760 inline void set_buf(HeapWord* buf) {
1761 if (use_local_bitmaps && _during_marking)
1762 _bitmap.set_buffer(buf);
1763 ParGCAllocBuffer::set_buf(buf);
1764 _retired = false;
1765 }
1767 inline void retire(bool end_of_gc, bool retain) {
1768 if (_retired)
1769 return;
1770 if (use_local_bitmaps && _during_marking) {
1771 _bitmap.retire();
1772 }
1773 ParGCAllocBuffer::retire(end_of_gc, retain);
1774 _retired = true;
1775 }
1776 };
1778 class G1ParScanThreadState : public StackObj {
1779 protected:
1780 G1CollectedHeap* _g1h;
1781 RefToScanQueue* _refs;
1782 DirtyCardQueue _dcq;
1783 CardTableModRefBS* _ct_bs;
1784 G1RemSet* _g1_rem;
1786 G1ParGCAllocBuffer _surviving_alloc_buffer;
1787 G1ParGCAllocBuffer _tenured_alloc_buffer;
1788 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1789 ageTable _age_table;
1791 size_t _alloc_buffer_waste;
1792 size_t _undo_waste;
1794 OopsInHeapRegionClosure* _evac_failure_cl;
1795 G1ParScanHeapEvacClosure* _evac_cl;
1796 G1ParScanPartialArrayClosure* _partial_scan_cl;
1798 int _hash_seed;
1799 int _queue_num;
1801 size_t _term_attempts;
1803 double _start;
1804 double _start_strong_roots;
1805 double _strong_roots_time;
1806 double _start_term;
1807 double _term_time;
1809 // Map from young-age-index (0 == not young, 1 is youngest) to
1810 // surviving words. base is what we get back from the malloc call
1811 size_t* _surviving_young_words_base;
1812 // this points into the array, as we use the first few entries for padding
1813 size_t* _surviving_young_words;
1815 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1817 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1819 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1821 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1822 CardTableModRefBS* ctbs() { return _ct_bs; }
1824 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1825 if (!from->is_survivor()) {
1826 _g1_rem->par_write_ref(from, p, tid);
1827 }
1828 }
1830 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1831 // If the new value of the field points to the same region or
1832 // is the to-space, we don't need to include it in the Rset updates.
1833 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1834 size_t card_index = ctbs()->index_for(p);
1835 // If the card hasn't been added to the buffer, do it.
1836 if (ctbs()->mark_card_deferred(card_index)) {
1837 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1838 }
1839 }
1840 }
1842 public:
1843 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1845 ~G1ParScanThreadState() {
1846 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1847 }
1849 RefToScanQueue* refs() { return _refs; }
1850 ageTable* age_table() { return &_age_table; }
1852 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1853 return _alloc_buffers[purpose];
1854 }
1856 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1857 size_t undo_waste() const { return _undo_waste; }
1859 #ifdef ASSERT
1860 bool verify_ref(narrowOop* ref) const;
1861 bool verify_ref(oop* ref) const;
1862 bool verify_task(StarTask ref) const;
1863 #endif // ASSERT
1865 template <class T> void push_on_queue(T* ref) {
1866 assert(verify_ref(ref), "sanity");
1867 refs()->push(ref);
1868 }
1870 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1871 if (G1DeferredRSUpdate) {
1872 deferred_rs_update(from, p, tid);
1873 } else {
1874 immediate_rs_update(from, p, tid);
1875 }
1876 }
1878 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1880 HeapWord* obj = NULL;
1881 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1882 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1883 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1884 assert(gclab_word_size == alloc_buf->word_sz(),
1885 "dynamic resizing is not supported");
1886 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1887 alloc_buf->retire(false, false);
1889 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1890 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1891 // Otherwise.
1892 alloc_buf->set_buf(buf);
1894 obj = alloc_buf->allocate(word_sz);
1895 assert(obj != NULL, "buffer was definitely big enough...");
1896 } else {
1897 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1898 }
1899 return obj;
1900 }
1902 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1903 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1904 if (obj != NULL) return obj;
1905 return allocate_slow(purpose, word_sz);
1906 }
1908 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1909 if (alloc_buffer(purpose)->contains(obj)) {
1910 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1911 "should contain whole object");
1912 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1913 } else {
1914 CollectedHeap::fill_with_object(obj, word_sz);
1915 add_to_undo_waste(word_sz);
1916 }
1917 }
1919 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1920 _evac_failure_cl = evac_failure_cl;
1921 }
1922 OopsInHeapRegionClosure* evac_failure_closure() {
1923 return _evac_failure_cl;
1924 }
1926 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1927 _evac_cl = evac_cl;
1928 }
1930 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1931 _partial_scan_cl = partial_scan_cl;
1932 }
1934 int* hash_seed() { return &_hash_seed; }
1935 int queue_num() { return _queue_num; }
1937 size_t term_attempts() const { return _term_attempts; }
1938 void note_term_attempt() { _term_attempts++; }
1940 void start_strong_roots() {
1941 _start_strong_roots = os::elapsedTime();
1942 }
1943 void end_strong_roots() {
1944 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1945 }
1946 double strong_roots_time() const { return _strong_roots_time; }
1948 void start_term_time() {
1949 note_term_attempt();
1950 _start_term = os::elapsedTime();
1951 }
1952 void end_term_time() {
1953 _term_time += (os::elapsedTime() - _start_term);
1954 }
1955 double term_time() const { return _term_time; }
1957 double elapsed_time() const {
1958 return os::elapsedTime() - _start;
1959 }
1961 static void
1962 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1963 void
1964 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1966 size_t* surviving_young_words() {
1967 // We add on to hide entry 0 which accumulates surviving words for
1968 // age -1 regions (i.e. non-young ones)
1969 return _surviving_young_words;
1970 }
1972 void retire_alloc_buffers() {
1973 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1974 size_t waste = _alloc_buffers[ap]->words_remaining();
1975 add_to_alloc_buffer_waste(waste);
1976 _alloc_buffers[ap]->retire(true, false);
1977 }
1978 }
1980 template <class T> void deal_with_reference(T* ref_to_scan) {
1981 if (has_partial_array_mask(ref_to_scan)) {
1982 _partial_scan_cl->do_oop_nv(ref_to_scan);
1983 } else {
1984 // Note: we can use "raw" versions of "region_containing" because
1985 // "obj_to_scan" is definitely in the heap, and is not in a
1986 // humongous region.
1987 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1988 _evac_cl->set_region(r);
1989 _evac_cl->do_oop_nv(ref_to_scan);
1990 }
1991 }
1993 void deal_with_reference(StarTask ref) {
1994 assert(verify_task(ref), "sanity");
1995 if (ref.is_narrow()) {
1996 deal_with_reference((narrowOop*)ref);
1997 } else {
1998 deal_with_reference((oop*)ref);
1999 }
2000 }
2002 public:
2003 void trim_queue();
2004 };
2006 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP