Fri, 18 Feb 2011 10:07:34 -0800
7020042: G1: Partially remove fix for 6994628
Summary: Disable reference discovery and processing during concurrent marking by disabling fix for 6994628.
Reviewed-by: tonyp, ysr
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
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/heapRegionSets.hpp"
32 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
33 #include "memory/barrierSet.hpp"
34 #include "memory/memRegion.hpp"
35 #include "memory/sharedHeap.hpp"
37 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
38 // It uses the "Garbage First" heap organization and algorithm, which
39 // may combine concurrent marking with parallel, incremental compaction of
40 // heap subsets that will yield large amounts of garbage.
42 class HeapRegion;
43 class HeapRegionSeq;
44 class HRRSCleanupTask;
45 class PermanentGenerationSpec;
46 class GenerationSpec;
47 class OopsInHeapRegionClosure;
48 class G1ScanHeapEvacClosure;
49 class ObjectClosure;
50 class SpaceClosure;
51 class CompactibleSpaceClosure;
52 class Space;
53 class G1CollectorPolicy;
54 class GenRemSet;
55 class G1RemSet;
56 class HeapRegionRemSetIterator;
57 class ConcurrentMark;
58 class ConcurrentMarkThread;
59 class ConcurrentG1Refine;
61 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
62 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
64 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
65 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
67 enum GCAllocPurpose {
68 GCAllocForTenured,
69 GCAllocForSurvived,
70 GCAllocPurposeCount
71 };
73 class YoungList : public CHeapObj {
74 private:
75 G1CollectedHeap* _g1h;
77 HeapRegion* _head;
79 HeapRegion* _survivor_head;
80 HeapRegion* _survivor_tail;
82 HeapRegion* _curr;
84 size_t _length;
85 size_t _survivor_length;
87 size_t _last_sampled_rs_lengths;
88 size_t _sampled_rs_lengths;
90 void empty_list(HeapRegion* list);
92 public:
93 YoungList(G1CollectedHeap* g1h);
95 void push_region(HeapRegion* hr);
96 void add_survivor_region(HeapRegion* hr);
98 void empty_list();
99 bool is_empty() { return _length == 0; }
100 size_t length() { return _length; }
101 size_t survivor_length() { return _survivor_length; }
103 void rs_length_sampling_init();
104 bool rs_length_sampling_more();
105 void rs_length_sampling_next();
107 void reset_sampled_info() {
108 _last_sampled_rs_lengths = 0;
109 }
110 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
112 // for development purposes
113 void reset_auxilary_lists();
114 void clear() { _head = NULL; _length = 0; }
116 void clear_survivors() {
117 _survivor_head = NULL;
118 _survivor_tail = NULL;
119 _survivor_length = 0;
120 }
122 HeapRegion* first_region() { return _head; }
123 HeapRegion* first_survivor_region() { return _survivor_head; }
124 HeapRegion* last_survivor_region() { return _survivor_tail; }
126 // debugging
127 bool check_list_well_formed();
128 bool check_list_empty(bool check_sample = true);
129 void print();
130 };
132 class MutatorAllocRegion : public G1AllocRegion {
133 protected:
134 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
135 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
136 public:
137 MutatorAllocRegion()
138 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
139 };
141 class RefineCardTableEntryClosure;
142 class G1CollectedHeap : public SharedHeap {
143 friend class VM_G1CollectForAllocation;
144 friend class VM_GenCollectForPermanentAllocation;
145 friend class VM_G1CollectFull;
146 friend class VM_G1IncCollectionPause;
147 friend class VMStructs;
148 friend class MutatorAllocRegion;
150 // Closures used in implementation.
151 friend class G1ParCopyHelper;
152 friend class G1IsAliveClosure;
153 friend class G1EvacuateFollowersClosure;
154 friend class G1ParScanThreadState;
155 friend class G1ParScanClosureSuper;
156 friend class G1ParEvacuateFollowersClosure;
157 friend class G1ParTask;
158 friend class G1FreeGarbageRegionClosure;
159 friend class RefineCardTableEntryClosure;
160 friend class G1PrepareCompactClosure;
161 friend class RegionSorter;
162 friend class RegionResetter;
163 friend class CountRCClosure;
164 friend class EvacPopObjClosure;
165 friend class G1ParCleanupCTTask;
167 // Other related classes.
168 friend class G1MarkSweep;
170 private:
171 // The one and only G1CollectedHeap, so static functions can find it.
172 static G1CollectedHeap* _g1h;
174 static size_t _humongous_object_threshold_in_words;
176 // Storage for the G1 heap (excludes the permanent generation).
177 VirtualSpace _g1_storage;
178 MemRegion _g1_reserved;
180 // The part of _g1_storage that is currently committed.
181 MemRegion _g1_committed;
183 // The maximum part of _g1_storage that has ever been committed.
184 MemRegion _g1_max_committed;
186 // The master free list. It will satisfy all new region allocations.
187 MasterFreeRegionList _free_list;
189 // The secondary free list which contains regions that have been
190 // freed up during the cleanup process. This will be appended to the
191 // master free list when appropriate.
192 SecondaryFreeRegionList _secondary_free_list;
194 // It keeps track of the humongous regions.
195 MasterHumongousRegionSet _humongous_set;
197 // The number of regions we could create by expansion.
198 size_t _expansion_regions;
200 // The block offset table for the G1 heap.
201 G1BlockOffsetSharedArray* _bot_shared;
203 // Move all of the regions off the free lists, then rebuild those free
204 // lists, before and after full GC.
205 void tear_down_region_lists();
206 void rebuild_region_lists();
208 // The sequence of all heap regions in the heap.
209 HeapRegionSeq* _hrs;
211 // Alloc region used to satisfy mutator allocation requests.
212 MutatorAllocRegion _mutator_alloc_region;
214 // It resets the mutator alloc region before new allocations can take place.
215 void init_mutator_alloc_region();
217 // It releases the mutator alloc region.
218 void release_mutator_alloc_region();
220 void abandon_gc_alloc_regions();
222 // The to-space memory regions into which objects are being copied during
223 // a GC.
224 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
225 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
226 // These are the regions, one per GCAllocPurpose, that are half-full
227 // at the end of a collection and that we want to reuse during the
228 // next collection.
229 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
230 // This specifies whether we will keep the last half-full region at
231 // the end of a collection so that it can be reused during the next
232 // collection (this is specified per GCAllocPurpose)
233 bool _retain_gc_alloc_region[GCAllocPurposeCount];
235 // A list of the regions that have been set to be alloc regions in the
236 // current collection.
237 HeapRegion* _gc_alloc_region_list;
239 // Determines PLAB size for a particular allocation purpose.
240 static size_t desired_plab_sz(GCAllocPurpose purpose);
242 // When called by par thread, requires the FreeList_lock to be held.
243 void push_gc_alloc_region(HeapRegion* hr);
245 // This should only be called single-threaded. Undeclares all GC alloc
246 // regions.
247 void forget_alloc_region_list();
249 // Should be used to set an alloc region, because there's other
250 // associated bookkeeping.
251 void set_gc_alloc_region(int purpose, HeapRegion* r);
253 // Check well-formedness of alloc region list.
254 bool check_gc_alloc_regions();
256 // Outside of GC pauses, the number of bytes used in all regions other
257 // than the current allocation region.
258 size_t _summary_bytes_used;
260 // This is used for a quick test on whether a reference points into
261 // the collection set or not. Basically, we have an array, with one
262 // byte per region, and that byte denotes whether the corresponding
263 // region is in the collection set or not. The entry corresponding
264 // the bottom of the heap, i.e., region 0, is pointed to by
265 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
266 // biased so that it actually points to address 0 of the address
267 // space, to make the test as fast as possible (we can simply shift
268 // the address to address into it, instead of having to subtract the
269 // bottom of the heap from the address before shifting it; basically
270 // it works in the same way the card table works).
271 bool* _in_cset_fast_test;
273 // The allocated array used for the fast test on whether a reference
274 // points into the collection set or not. This field is also used to
275 // free the array.
276 bool* _in_cset_fast_test_base;
278 // The length of the _in_cset_fast_test_base array.
279 size_t _in_cset_fast_test_length;
281 volatile unsigned _gc_time_stamp;
283 size_t* _surviving_young_words;
285 void setup_surviving_young_words();
286 void update_surviving_young_words(size_t* surv_young_words);
287 void cleanup_surviving_young_words();
289 // It decides whether an explicit GC should start a concurrent cycle
290 // instead of doing a STW GC. Currently, a concurrent cycle is
291 // explicitly started if:
292 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
293 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
294 bool should_do_concurrent_full_gc(GCCause::Cause cause);
296 // Keeps track of how many "full collections" (i.e., Full GCs or
297 // concurrent cycles) we have completed. The number of them we have
298 // started is maintained in _total_full_collections in CollectedHeap.
299 volatile unsigned int _full_collections_completed;
301 // These are macros so that, if the assert fires, we get the correct
302 // line number, file, etc.
304 #define heap_locking_asserts_err_msg(_extra_message_) \
305 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
306 (_extra_message_), \
307 BOOL_TO_STR(Heap_lock->owned_by_self()), \
308 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
309 BOOL_TO_STR(Thread::current()->is_VM_thread()))
311 #define assert_heap_locked() \
312 do { \
313 assert(Heap_lock->owned_by_self(), \
314 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
315 } while (0)
317 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
318 do { \
319 assert(Heap_lock->owned_by_self() || \
320 (SafepointSynchronize::is_at_safepoint() && \
321 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
322 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
323 "should be at a safepoint")); \
324 } while (0)
326 #define assert_heap_locked_and_not_at_safepoint() \
327 do { \
328 assert(Heap_lock->owned_by_self() && \
329 !SafepointSynchronize::is_at_safepoint(), \
330 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
331 "should not be at a safepoint")); \
332 } while (0)
334 #define assert_heap_not_locked() \
335 do { \
336 assert(!Heap_lock->owned_by_self(), \
337 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
338 } while (0)
340 #define assert_heap_not_locked_and_not_at_safepoint() \
341 do { \
342 assert(!Heap_lock->owned_by_self() && \
343 !SafepointSynchronize::is_at_safepoint(), \
344 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
345 "should not be at a safepoint")); \
346 } while (0)
348 #define assert_at_safepoint(_should_be_vm_thread_) \
349 do { \
350 assert(SafepointSynchronize::is_at_safepoint() && \
351 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
352 heap_locking_asserts_err_msg("should be at a safepoint")); \
353 } while (0)
355 #define assert_not_at_safepoint() \
356 do { \
357 assert(!SafepointSynchronize::is_at_safepoint(), \
358 heap_locking_asserts_err_msg("should not be at a safepoint")); \
359 } while (0)
361 protected:
363 // Returns "true" iff none of the gc alloc regions have any allocations
364 // since the last call to "save_marks".
365 bool all_alloc_regions_no_allocs_since_save_marks();
366 // Perform finalization stuff on all allocation regions.
367 void retire_all_alloc_regions();
369 // The number of regions allocated to hold humongous objects.
370 int _num_humongous_regions;
371 YoungList* _young_list;
373 // The current policy object for the collector.
374 G1CollectorPolicy* _g1_policy;
376 // This is the second level of trying to allocate a new region. If
377 // new_region() didn't find a region on the free_list, this call will
378 // check whether there's anything available on the
379 // secondary_free_list and/or wait for more regions to appear on
380 // that list, if _free_regions_coming is set.
381 HeapRegion* new_region_try_secondary_free_list();
383 // Try to allocate a single non-humongous HeapRegion sufficient for
384 // an allocation of the given word_size. If do_expand is true,
385 // attempt to expand the heap if necessary to satisfy the allocation
386 // request.
387 HeapRegion* new_region(size_t word_size, bool do_expand);
389 // Try to allocate a new region to be used for allocation by
390 // a GC thread. It will try to expand the heap if no region is
391 // available.
392 HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
394 // Attempt to satisfy a humongous allocation request of the given
395 // size by finding a contiguous set of free regions of num_regions
396 // length and remove them from the master free list. Return the
397 // index of the first region or -1 if the search was unsuccessful.
398 int humongous_obj_allocate_find_first(size_t num_regions, size_t word_size);
400 // Initialize a contiguous set of free regions of length num_regions
401 // and starting at index first so that they appear as a single
402 // humongous region.
403 HeapWord* humongous_obj_allocate_initialize_regions(int first,
404 size_t num_regions,
405 size_t word_size);
407 // Attempt to allocate a humongous object of the given size. Return
408 // NULL if unsuccessful.
409 HeapWord* humongous_obj_allocate(size_t word_size);
411 // The following two methods, allocate_new_tlab() and
412 // mem_allocate(), are the two main entry points from the runtime
413 // into the G1's allocation routines. They have the following
414 // assumptions:
415 //
416 // * They should both be called outside safepoints.
417 //
418 // * They should both be called without holding the Heap_lock.
419 //
420 // * All allocation requests for new TLABs should go to
421 // allocate_new_tlab().
422 //
423 // * All non-TLAB allocation requests should go to mem_allocate()
424 // and mem_allocate() should never be called with is_tlab == true.
425 //
426 // * If either call cannot satisfy the allocation request using the
427 // current allocating region, they will try to get a new one. If
428 // this fails, they will attempt to do an evacuation pause and
429 // retry the allocation.
430 //
431 // * If all allocation attempts fail, even after trying to schedule
432 // an evacuation pause, allocate_new_tlab() will return NULL,
433 // whereas mem_allocate() will attempt a heap expansion and/or
434 // schedule a Full GC.
435 //
436 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
437 // should never be called with word_size being humongous. All
438 // humongous allocation requests should go to mem_allocate() which
439 // will satisfy them with a special path.
441 virtual HeapWord* allocate_new_tlab(size_t word_size);
443 virtual HeapWord* mem_allocate(size_t word_size,
444 bool is_noref,
445 bool is_tlab, /* expected to be false */
446 bool* gc_overhead_limit_was_exceeded);
448 // The following three methods take a gc_count_before_ret
449 // parameter which is used to return the GC count if the method
450 // returns NULL. Given that we are required to read the GC count
451 // while holding the Heap_lock, and these paths will take the
452 // Heap_lock at some point, it's easier to get them to read the GC
453 // count while holding the Heap_lock before they return NULL instead
454 // of the caller (namely: mem_allocate()) having to also take the
455 // Heap_lock just to read the GC count.
457 // First-level mutator allocation attempt: try to allocate out of
458 // the mutator alloc region without taking the Heap_lock. This
459 // should only be used for non-humongous allocations.
460 inline HeapWord* attempt_allocation(size_t word_size,
461 unsigned int* gc_count_before_ret);
463 // Second-level mutator allocation attempt: take the Heap_lock and
464 // retry the allocation attempt, potentially scheduling a GC
465 // pause. This should only be used for non-humongous allocations.
466 HeapWord* attempt_allocation_slow(size_t word_size,
467 unsigned int* gc_count_before_ret);
469 // Takes the Heap_lock and attempts a humongous allocation. It can
470 // potentially schedule a GC pause.
471 HeapWord* attempt_allocation_humongous(size_t word_size,
472 unsigned int* gc_count_before_ret);
474 // Allocation attempt that should be called during safepoints (e.g.,
475 // at the end of a successful GC). expect_null_mutator_alloc_region
476 // specifies whether the mutator alloc region is expected to be NULL
477 // or not.
478 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
479 bool expect_null_mutator_alloc_region);
481 // It dirties the cards that cover the block so that so that the post
482 // write barrier never queues anything when updating objects on this
483 // block. It is assumed (and in fact we assert) that the block
484 // belongs to a young region.
485 inline void dirty_young_block(HeapWord* start, size_t word_size);
487 // Allocate blocks during garbage collection. Will ensure an
488 // allocation region, either by picking one or expanding the
489 // heap, and then allocate a block of the given size. The block
490 // may not be a humongous - it must fit into a single heap region.
491 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
493 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
494 HeapRegion* alloc_region,
495 bool par,
496 size_t word_size);
498 // Ensure that no further allocations can happen in "r", bearing in mind
499 // that parallel threads might be attempting allocations.
500 void par_allocate_remaining_space(HeapRegion* r);
502 // Retires an allocation region when it is full or at the end of a
503 // GC pause.
504 void retire_alloc_region(HeapRegion* alloc_region, bool par);
506 // These two methods are the "callbacks" from the G1AllocRegion class.
508 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
509 void retire_mutator_alloc_region(HeapRegion* alloc_region,
510 size_t allocated_bytes);
512 // - if explicit_gc is true, the GC is for a System.gc() or a heap
513 // inspection request and should collect the entire heap
514 // - if clear_all_soft_refs is true, all soft references should be
515 // cleared during the GC
516 // - if explicit_gc is false, word_size describes the allocation that
517 // the GC should attempt (at least) to satisfy
518 // - it returns false if it is unable to do the collection due to the
519 // GC locker being active, true otherwise
520 bool do_collection(bool explicit_gc,
521 bool clear_all_soft_refs,
522 size_t word_size);
524 // Callback from VM_G1CollectFull operation.
525 // Perform a full collection.
526 void do_full_collection(bool clear_all_soft_refs);
528 // Resize the heap if necessary after a full collection. If this is
529 // after a collect-for allocation, "word_size" is the allocation size,
530 // and will be considered part of the used portion of the heap.
531 void resize_if_necessary_after_full_collection(size_t word_size);
533 // Callback from VM_G1CollectForAllocation operation.
534 // This function does everything necessary/possible to satisfy a
535 // failed allocation request (including collection, expansion, etc.)
536 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
538 // Attempting to expand the heap sufficiently
539 // to support an allocation of the given "word_size". If
540 // successful, perform the allocation and return the address of the
541 // allocated block, or else "NULL".
542 HeapWord* expand_and_allocate(size_t word_size);
544 public:
545 // Expand the garbage-first heap by at least the given size (in bytes!).
546 // Returns true if the heap was expanded by the requested amount;
547 // false otherwise.
548 // (Rounds up to a HeapRegion boundary.)
549 bool expand(size_t expand_bytes);
551 // Do anything common to GC's.
552 virtual void gc_prologue(bool full);
553 virtual void gc_epilogue(bool full);
555 // We register a region with the fast "in collection set" test. We
556 // simply set to true the array slot corresponding to this region.
557 void register_region_with_in_cset_fast_test(HeapRegion* r) {
558 assert(_in_cset_fast_test_base != NULL, "sanity");
559 assert(r->in_collection_set(), "invariant");
560 int index = r->hrs_index();
561 assert(0 <= index && (size_t) index < _in_cset_fast_test_length, "invariant");
562 assert(!_in_cset_fast_test_base[index], "invariant");
563 _in_cset_fast_test_base[index] = true;
564 }
566 // This is a fast test on whether a reference points into the
567 // collection set or not. It does not assume that the reference
568 // points into the heap; if it doesn't, it will return false.
569 bool in_cset_fast_test(oop obj) {
570 assert(_in_cset_fast_test != NULL, "sanity");
571 if (_g1_committed.contains((HeapWord*) obj)) {
572 // no need to subtract the bottom of the heap from obj,
573 // _in_cset_fast_test is biased
574 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
575 bool ret = _in_cset_fast_test[index];
576 // let's make sure the result is consistent with what the slower
577 // test returns
578 assert( ret || !obj_in_cs(obj), "sanity");
579 assert(!ret || obj_in_cs(obj), "sanity");
580 return ret;
581 } else {
582 return false;
583 }
584 }
586 void clear_cset_fast_test() {
587 assert(_in_cset_fast_test_base != NULL, "sanity");
588 memset(_in_cset_fast_test_base, false,
589 _in_cset_fast_test_length * sizeof(bool));
590 }
592 // This is called at the end of either a concurrent cycle or a Full
593 // GC to update the number of full collections completed. Those two
594 // can happen in a nested fashion, i.e., we start a concurrent
595 // cycle, a Full GC happens half-way through it which ends first,
596 // and then the cycle notices that a Full GC happened and ends
597 // too. The concurrent parameter is a boolean to help us do a bit
598 // tighter consistency checking in the method. If concurrent is
599 // false, the caller is the inner caller in the nesting (i.e., the
600 // Full GC). If concurrent is true, the caller is the outer caller
601 // in this nesting (i.e., the concurrent cycle). Further nesting is
602 // not currently supported. The end of the this call also notifies
603 // the FullGCCount_lock in case a Java thread is waiting for a full
604 // GC to happen (e.g., it called System.gc() with
605 // +ExplicitGCInvokesConcurrent).
606 void increment_full_collections_completed(bool concurrent);
608 unsigned int full_collections_completed() {
609 return _full_collections_completed;
610 }
612 protected:
614 // Shrink the garbage-first heap by at most the given size (in bytes!).
615 // (Rounds down to a HeapRegion boundary.)
616 virtual void shrink(size_t expand_bytes);
617 void shrink_helper(size_t expand_bytes);
619 #if TASKQUEUE_STATS
620 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
621 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
622 void reset_taskqueue_stats();
623 #endif // TASKQUEUE_STATS
625 // Schedule the VM operation that will do an evacuation pause to
626 // satisfy an allocation request of word_size. *succeeded will
627 // return whether the VM operation was successful (it did do an
628 // evacuation pause) or not (another thread beat us to it or the GC
629 // locker was active). Given that we should not be holding the
630 // Heap_lock when we enter this method, we will pass the
631 // gc_count_before (i.e., total_collections()) as a parameter since
632 // it has to be read while holding the Heap_lock. Currently, both
633 // methods that call do_collection_pause() release the Heap_lock
634 // before the call, so it's easy to read gc_count_before just before.
635 HeapWord* do_collection_pause(size_t word_size,
636 unsigned int gc_count_before,
637 bool* succeeded);
639 // The guts of the incremental collection pause, executed by the vm
640 // thread. It returns false if it is unable to do the collection due
641 // to the GC locker being active, true otherwise
642 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
644 // Actually do the work of evacuating the collection set.
645 void evacuate_collection_set();
647 // The g1 remembered set of the heap.
648 G1RemSet* _g1_rem_set;
649 // And it's mod ref barrier set, used to track updates for the above.
650 ModRefBarrierSet* _mr_bs;
652 // A set of cards that cover the objects for which the Rsets should be updated
653 // concurrently after the collection.
654 DirtyCardQueueSet _dirty_card_queue_set;
656 // The Heap Region Rem Set Iterator.
657 HeapRegionRemSetIterator** _rem_set_iterator;
659 // The closure used to refine a single card.
660 RefineCardTableEntryClosure* _refine_cte_cl;
662 // A function to check the consistency of dirty card logs.
663 void check_ct_logs_at_safepoint();
665 // A DirtyCardQueueSet that is used to hold cards that contain
666 // references into the current collection set. This is used to
667 // update the remembered sets of the regions in the collection
668 // set in the event of an evacuation failure.
669 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
671 // After a collection pause, make the regions in the CS into free
672 // regions.
673 void free_collection_set(HeapRegion* cs_head);
675 // Abandon the current collection set without recording policy
676 // statistics or updating free lists.
677 void abandon_collection_set(HeapRegion* cs_head);
679 // Applies "scan_non_heap_roots" to roots outside the heap,
680 // "scan_rs" to roots inside the heap (having done "set_region" to
681 // indicate the region in which the root resides), and does "scan_perm"
682 // (setting the generation to the perm generation.) If "scan_rs" is
683 // NULL, then this step is skipped. The "worker_i"
684 // param is for use with parallel roots processing, and should be
685 // the "i" of the calling parallel worker thread's work(i) function.
686 // In the sequential case this param will be ignored.
687 void g1_process_strong_roots(bool collecting_perm_gen,
688 SharedHeap::ScanningOption so,
689 OopClosure* scan_non_heap_roots,
690 OopsInHeapRegionClosure* scan_rs,
691 OopsInGenClosure* scan_perm,
692 int worker_i);
694 // Apply "blk" to all the weak roots of the system. These include
695 // JNI weak roots, the code cache, system dictionary, symbol table,
696 // string table, and referents of reachable weak refs.
697 void g1_process_weak_roots(OopClosure* root_closure,
698 OopClosure* non_root_closure);
700 // Invoke "save_marks" on all heap regions.
701 void save_marks();
703 // Frees a non-humongous region by initializing its contents and
704 // adding it to the free list that's passed as a parameter (this is
705 // usually a local list which will be appended to the master free
706 // list later). The used bytes of freed regions are accumulated in
707 // pre_used. If par is true, the region's RSet will not be freed
708 // up. The assumption is that this will be done later.
709 void free_region(HeapRegion* hr,
710 size_t* pre_used,
711 FreeRegionList* free_list,
712 bool par);
714 // Frees a humongous region by collapsing it into individual regions
715 // and calling free_region() for each of them. The freed regions
716 // will be added to the free list that's passed as a parameter (this
717 // is usually a local list which will be appended to the master free
718 // list later). The used bytes of freed regions are accumulated in
719 // pre_used. If par is true, the region's RSet will not be freed
720 // up. The assumption is that this will be done later.
721 void free_humongous_region(HeapRegion* hr,
722 size_t* pre_used,
723 FreeRegionList* free_list,
724 HumongousRegionSet* humongous_proxy_set,
725 bool par);
727 // The concurrent marker (and the thread it runs in.)
728 ConcurrentMark* _cm;
729 ConcurrentMarkThread* _cmThread;
730 bool _mark_in_progress;
732 // The concurrent refiner.
733 ConcurrentG1Refine* _cg1r;
735 // The parallel task queues
736 RefToScanQueueSet *_task_queues;
738 // True iff a evacuation has failed in the current collection.
739 bool _evacuation_failed;
741 // Set the attribute indicating whether evacuation has failed in the
742 // current collection.
743 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
745 // Failed evacuations cause some logical from-space objects to have
746 // forwarding pointers to themselves. Reset them.
747 void remove_self_forwarding_pointers();
749 // When one is non-null, so is the other. Together, they each pair is
750 // an object with a preserved mark, and its mark value.
751 GrowableArray<oop>* _objs_with_preserved_marks;
752 GrowableArray<markOop>* _preserved_marks_of_objs;
754 // Preserve the mark of "obj", if necessary, in preparation for its mark
755 // word being overwritten with a self-forwarding-pointer.
756 void preserve_mark_if_necessary(oop obj, markOop m);
758 // The stack of evac-failure objects left to be scanned.
759 GrowableArray<oop>* _evac_failure_scan_stack;
760 // The closure to apply to evac-failure objects.
762 OopsInHeapRegionClosure* _evac_failure_closure;
763 // Set the field above.
764 void
765 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
766 _evac_failure_closure = evac_failure_closure;
767 }
769 // Push "obj" on the scan stack.
770 void push_on_evac_failure_scan_stack(oop obj);
771 // Process scan stack entries until the stack is empty.
772 void drain_evac_failure_scan_stack();
773 // True iff an invocation of "drain_scan_stack" is in progress; to
774 // prevent unnecessary recursion.
775 bool _drain_in_progress;
777 // Do any necessary initialization for evacuation-failure handling.
778 // "cl" is the closure that will be used to process evac-failure
779 // objects.
780 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
781 // Do any necessary cleanup for evacuation-failure handling data
782 // structures.
783 void finalize_for_evac_failure();
785 // An attempt to evacuate "obj" has failed; take necessary steps.
786 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
787 void handle_evacuation_failure_common(oop obj, markOop m);
790 // Ensure that the relevant gc_alloc regions are set.
791 void get_gc_alloc_regions();
792 // We're done with GC alloc regions. We are going to tear down the
793 // gc alloc list and remove the gc alloc tag from all the regions on
794 // that list. However, we will also retain the last (i.e., the one
795 // that is half-full) GC alloc region, per GCAllocPurpose, for
796 // possible reuse during the next collection, provided
797 // _retain_gc_alloc_region[] indicates that it should be the
798 // case. Said regions are kept in the _retained_gc_alloc_regions[]
799 // array. If the parameter totally is set, we will not retain any
800 // regions, irrespective of what _retain_gc_alloc_region[]
801 // indicates.
802 void release_gc_alloc_regions(bool totally);
803 #ifndef PRODUCT
804 // Useful for debugging.
805 void print_gc_alloc_regions();
806 #endif // !PRODUCT
808 // Instance of the concurrent mark is_alive closure for embedding
809 // into the reference processor as the is_alive_non_header. This
810 // prevents unnecessary additions to the discovered lists during
811 // concurrent discovery.
812 G1CMIsAliveClosure _is_alive_closure;
814 // ("Weak") Reference processing support
815 ReferenceProcessor* _ref_processor;
817 enum G1H_process_strong_roots_tasks {
818 G1H_PS_mark_stack_oops_do,
819 G1H_PS_refProcessor_oops_do,
820 // Leave this one last.
821 G1H_PS_NumElements
822 };
824 SubTasksDone* _process_strong_tasks;
826 volatile bool _free_regions_coming;
828 public:
830 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
832 void set_refine_cte_cl_concurrency(bool concurrent);
834 RefToScanQueue *task_queue(int i) const;
836 // A set of cards where updates happened during the GC
837 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
839 // A DirtyCardQueueSet that is used to hold cards that contain
840 // references into the current collection set. This is used to
841 // update the remembered sets of the regions in the collection
842 // set in the event of an evacuation failure.
843 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
844 { return _into_cset_dirty_card_queue_set; }
846 // Create a G1CollectedHeap with the specified policy.
847 // Must call the initialize method afterwards.
848 // May not return if something goes wrong.
849 G1CollectedHeap(G1CollectorPolicy* policy);
851 // Initialize the G1CollectedHeap to have the initial and
852 // maximum sizes, permanent generation, and remembered and barrier sets
853 // specified by the policy object.
854 jint initialize();
856 virtual void ref_processing_init();
858 void set_par_threads(int t) {
859 SharedHeap::set_par_threads(t);
860 _process_strong_tasks->set_n_threads(t);
861 }
863 virtual CollectedHeap::Name kind() const {
864 return CollectedHeap::G1CollectedHeap;
865 }
867 // The current policy object for the collector.
868 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
870 // Adaptive size policy. No such thing for g1.
871 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
873 // The rem set and barrier set.
874 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
875 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
877 // The rem set iterator.
878 HeapRegionRemSetIterator* rem_set_iterator(int i) {
879 return _rem_set_iterator[i];
880 }
882 HeapRegionRemSetIterator* rem_set_iterator() {
883 return _rem_set_iterator[0];
884 }
886 unsigned get_gc_time_stamp() {
887 return _gc_time_stamp;
888 }
890 void reset_gc_time_stamp() {
891 _gc_time_stamp = 0;
892 OrderAccess::fence();
893 }
895 void increment_gc_time_stamp() {
896 ++_gc_time_stamp;
897 OrderAccess::fence();
898 }
900 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
901 DirtyCardQueue* into_cset_dcq,
902 bool concurrent, int worker_i);
904 // The shared block offset table array.
905 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
907 // Reference Processing accessor
908 ReferenceProcessor* ref_processor() { return _ref_processor; }
910 virtual size_t capacity() const;
911 virtual size_t used() const;
912 // This should be called when we're not holding the heap lock. The
913 // result might be a bit inaccurate.
914 size_t used_unlocked() const;
915 size_t recalculate_used() const;
916 #ifndef PRODUCT
917 size_t recalculate_used_regions() const;
918 #endif // PRODUCT
920 // These virtual functions do the actual allocation.
921 // Some heaps may offer a contiguous region for shared non-blocking
922 // allocation, via inlined code (by exporting the address of the top and
923 // end fields defining the extent of the contiguous allocation region.)
924 // But G1CollectedHeap doesn't yet support this.
926 // Return an estimate of the maximum allocation that could be performed
927 // without triggering any collection or expansion activity. In a
928 // generational collector, for example, this is probably the largest
929 // allocation that could be supported (without expansion) in the youngest
930 // generation. It is "unsafe" because no locks are taken; the result
931 // should be treated as an approximation, not a guarantee, for use in
932 // heuristic resizing decisions.
933 virtual size_t unsafe_max_alloc();
935 virtual bool is_maximal_no_gc() const {
936 return _g1_storage.uncommitted_size() == 0;
937 }
939 // The total number of regions in the heap.
940 size_t n_regions();
942 // The number of regions that are completely free.
943 size_t max_regions();
945 // The number of regions that are completely free.
946 size_t free_regions() {
947 return _free_list.length();
948 }
950 // The number of regions that are not completely free.
951 size_t used_regions() { return n_regions() - free_regions(); }
953 // The number of regions available for "regular" expansion.
954 size_t expansion_regions() { return _expansion_regions; }
956 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
957 void verify_dirty_young_regions() PRODUCT_RETURN;
959 // verify_region_sets() performs verification over the region
960 // lists. It will be compiled in the product code to be used when
961 // necessary (i.e., during heap verification).
962 void verify_region_sets();
964 // verify_region_sets_optional() is planted in the code for
965 // list verification in non-product builds (and it can be enabled in
966 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
967 #if HEAP_REGION_SET_FORCE_VERIFY
968 void verify_region_sets_optional() {
969 verify_region_sets();
970 }
971 #else // HEAP_REGION_SET_FORCE_VERIFY
972 void verify_region_sets_optional() { }
973 #endif // HEAP_REGION_SET_FORCE_VERIFY
975 #ifdef ASSERT
976 bool is_on_master_free_list(HeapRegion* hr) {
977 return hr->containing_set() == &_free_list;
978 }
980 bool is_in_humongous_set(HeapRegion* hr) {
981 return hr->containing_set() == &_humongous_set;
982 }
983 #endif // ASSERT
985 // Wrapper for the region list operations that can be called from
986 // methods outside this class.
988 void secondary_free_list_add_as_tail(FreeRegionList* list) {
989 _secondary_free_list.add_as_tail(list);
990 }
992 void append_secondary_free_list() {
993 _free_list.add_as_head(&_secondary_free_list);
994 }
996 void append_secondary_free_list_if_not_empty_with_lock() {
997 // If the secondary free list looks empty there's no reason to
998 // take the lock and then try to append it.
999 if (!_secondary_free_list.is_empty()) {
1000 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1001 append_secondary_free_list();
1002 }
1003 }
1005 void set_free_regions_coming();
1006 void reset_free_regions_coming();
1007 bool free_regions_coming() { return _free_regions_coming; }
1008 void wait_while_free_regions_coming();
1010 // Perform a collection of the heap; intended for use in implementing
1011 // "System.gc". This probably implies as full a collection as the
1012 // "CollectedHeap" supports.
1013 virtual void collect(GCCause::Cause cause);
1015 // The same as above but assume that the caller holds the Heap_lock.
1016 void collect_locked(GCCause::Cause cause);
1018 // This interface assumes that it's being called by the
1019 // vm thread. It collects the heap assuming that the
1020 // heap lock is already held and that we are executing in
1021 // the context of the vm thread.
1022 virtual void collect_as_vm_thread(GCCause::Cause cause);
1024 // True iff a evacuation has failed in the most-recent collection.
1025 bool evacuation_failed() { return _evacuation_failed; }
1027 // It will free a region if it has allocated objects in it that are
1028 // all dead. It calls either free_region() or
1029 // free_humongous_region() depending on the type of the region that
1030 // is passed to it.
1031 void free_region_if_empty(HeapRegion* hr,
1032 size_t* pre_used,
1033 FreeRegionList* free_list,
1034 HumongousRegionSet* humongous_proxy_set,
1035 HRRSCleanupTask* hrrs_cleanup_task,
1036 bool par);
1038 // It appends the free list to the master free list and updates the
1039 // master humongous list according to the contents of the proxy
1040 // list. It also adjusts the total used bytes according to pre_used
1041 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1042 void update_sets_after_freeing_regions(size_t pre_used,
1043 FreeRegionList* free_list,
1044 HumongousRegionSet* humongous_proxy_set,
1045 bool par);
1047 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1048 virtual bool is_in(const void* p) const;
1050 // Return "TRUE" iff the given object address is within the collection
1051 // set.
1052 inline bool obj_in_cs(oop obj);
1054 // Return "TRUE" iff the given object address is in the reserved
1055 // region of g1 (excluding the permanent generation).
1056 bool is_in_g1_reserved(const void* p) const {
1057 return _g1_reserved.contains(p);
1058 }
1060 // Returns a MemRegion that corresponds to the space that has been
1061 // reserved for the heap
1062 MemRegion g1_reserved() {
1063 return _g1_reserved;
1064 }
1066 // Returns a MemRegion that corresponds to the space that has been
1067 // committed in the heap
1068 MemRegion g1_committed() {
1069 return _g1_committed;
1070 }
1072 virtual bool is_in_closed_subset(const void* p) const;
1074 // Dirty card table entries covering a list of young regions.
1075 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1077 // This resets the card table to all zeros. It is used after
1078 // a collection pause which used the card table to claim cards.
1079 void cleanUpCardTable();
1081 // Iteration functions.
1083 // Iterate over all the ref-containing fields of all objects, calling
1084 // "cl.do_oop" on each.
1085 virtual void oop_iterate(OopClosure* cl) {
1086 oop_iterate(cl, true);
1087 }
1088 void oop_iterate(OopClosure* cl, bool do_perm);
1090 // Same as above, restricted to a memory region.
1091 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1092 oop_iterate(mr, cl, true);
1093 }
1094 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1096 // Iterate over all objects, calling "cl.do_object" on each.
1097 virtual void object_iterate(ObjectClosure* cl) {
1098 object_iterate(cl, true);
1099 }
1100 virtual void safe_object_iterate(ObjectClosure* cl) {
1101 object_iterate(cl, true);
1102 }
1103 void object_iterate(ObjectClosure* cl, bool do_perm);
1105 // Iterate over all objects allocated since the last collection, calling
1106 // "cl.do_object" on each. The heap must have been initialized properly
1107 // to support this function, or else this call will fail.
1108 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1110 // Iterate over all spaces in use in the heap, in ascending address order.
1111 virtual void space_iterate(SpaceClosure* cl);
1113 // Iterate over heap regions, in address order, terminating the
1114 // iteration early if the "doHeapRegion" method returns "true".
1115 void heap_region_iterate(HeapRegionClosure* blk);
1117 // Iterate over heap regions starting with r (or the first region if "r"
1118 // is NULL), in address order, terminating early if the "doHeapRegion"
1119 // method returns "true".
1120 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk);
1122 // As above but starting from the region at index idx.
1123 void heap_region_iterate_from(int idx, HeapRegionClosure* blk);
1125 HeapRegion* region_at(size_t idx);
1127 // Divide the heap region sequence into "chunks" of some size (the number
1128 // of regions divided by the number of parallel threads times some
1129 // overpartition factor, currently 4). Assumes that this will be called
1130 // in parallel by ParallelGCThreads worker threads with discinct worker
1131 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1132 // calls will use the same "claim_value", and that that claim value is
1133 // different from the claim_value of any heap region before the start of
1134 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1135 // attempting to claim the first region in each chunk, and, if
1136 // successful, applying the closure to each region in the chunk (and
1137 // setting the claim value of the second and subsequent regions of the
1138 // chunk.) For now requires that "doHeapRegion" always returns "false",
1139 // i.e., that a closure never attempt to abort a traversal.
1140 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1141 int worker,
1142 jint claim_value);
1144 // It resets all the region claim values to the default.
1145 void reset_heap_region_claim_values();
1147 #ifdef ASSERT
1148 bool check_heap_region_claim_values(jint claim_value);
1149 #endif // ASSERT
1151 // Iterate over the regions (if any) in the current collection set.
1152 void collection_set_iterate(HeapRegionClosure* blk);
1154 // As above but starting from region r
1155 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1157 // Returns the first (lowest address) compactible space in the heap.
1158 virtual CompactibleSpace* first_compactible_space();
1160 // A CollectedHeap will contain some number of spaces. This finds the
1161 // space containing a given address, or else returns NULL.
1162 virtual Space* space_containing(const void* addr) const;
1164 // A G1CollectedHeap will contain some number of heap regions. This
1165 // finds the region containing a given address, or else returns NULL.
1166 HeapRegion* heap_region_containing(const void* addr) const;
1168 // Like the above, but requires "addr" to be in the heap (to avoid a
1169 // null-check), and unlike the above, may return an continuing humongous
1170 // region.
1171 HeapRegion* heap_region_containing_raw(const void* addr) const;
1173 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1174 // each address in the (reserved) heap is a member of exactly
1175 // one block. The defining characteristic of a block is that it is
1176 // possible to find its size, and thus to progress forward to the next
1177 // block. (Blocks may be of different sizes.) Thus, blocks may
1178 // represent Java objects, or they might be free blocks in a
1179 // free-list-based heap (or subheap), as long as the two kinds are
1180 // distinguishable and the size of each is determinable.
1182 // Returns the address of the start of the "block" that contains the
1183 // address "addr". We say "blocks" instead of "object" since some heaps
1184 // may not pack objects densely; a chunk may either be an object or a
1185 // non-object.
1186 virtual HeapWord* block_start(const void* addr) const;
1188 // Requires "addr" to be the start of a chunk, and returns its size.
1189 // "addr + size" is required to be the start of a new chunk, or the end
1190 // of the active area of the heap.
1191 virtual size_t block_size(const HeapWord* addr) const;
1193 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1194 // the block is an object.
1195 virtual bool block_is_obj(const HeapWord* addr) const;
1197 // Does this heap support heap inspection? (+PrintClassHistogram)
1198 virtual bool supports_heap_inspection() const { return true; }
1200 // Section on thread-local allocation buffers (TLABs)
1201 // See CollectedHeap for semantics.
1203 virtual bool supports_tlab_allocation() const;
1204 virtual size_t tlab_capacity(Thread* thr) const;
1205 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1207 // Can a compiler initialize a new object without store barriers?
1208 // This permission only extends from the creation of a new object
1209 // via a TLAB up to the first subsequent safepoint. If such permission
1210 // is granted for this heap type, the compiler promises to call
1211 // defer_store_barrier() below on any slow path allocation of
1212 // a new object for which such initializing store barriers will
1213 // have been elided. G1, like CMS, allows this, but should be
1214 // ready to provide a compensating write barrier as necessary
1215 // if that storage came out of a non-young region. The efficiency
1216 // of this implementation depends crucially on being able to
1217 // answer very efficiently in constant time whether a piece of
1218 // storage in the heap comes from a young region or not.
1219 // See ReduceInitialCardMarks.
1220 virtual bool can_elide_tlab_store_barriers() const {
1221 // 6920090: Temporarily disabled, because of lingering
1222 // instabilities related to RICM with G1. In the
1223 // interim, the option ReduceInitialCardMarksForG1
1224 // below is left solely as a debugging device at least
1225 // until 6920109 fixes the instabilities.
1226 return ReduceInitialCardMarksForG1;
1227 }
1229 virtual bool card_mark_must_follow_store() const {
1230 return true;
1231 }
1233 bool is_in_young(oop obj) {
1234 HeapRegion* hr = heap_region_containing(obj);
1235 return hr != NULL && hr->is_young();
1236 }
1238 // We don't need barriers for initializing stores to objects
1239 // in the young gen: for the SATB pre-barrier, there is no
1240 // pre-value that needs to be remembered; for the remembered-set
1241 // update logging post-barrier, we don't maintain remembered set
1242 // information for young gen objects. Note that non-generational
1243 // G1 does not have any "young" objects, should not elide
1244 // the rs logging barrier and so should always answer false below.
1245 // However, non-generational G1 (-XX:-G1Gen) appears to have
1246 // bit-rotted so was not tested below.
1247 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1248 // Re 6920090, 6920109 above.
1249 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1250 assert(G1Gen || !is_in_young(new_obj),
1251 "Non-generational G1 should never return true below");
1252 return is_in_young(new_obj);
1253 }
1255 // Can a compiler elide a store barrier when it writes
1256 // a permanent oop into the heap? Applies when the compiler
1257 // is storing x to the heap, where x->is_perm() is true.
1258 virtual bool can_elide_permanent_oop_store_barriers() const {
1259 // At least until perm gen collection is also G1-ified, at
1260 // which point this should return false.
1261 return true;
1262 }
1264 // The boundary between a "large" and "small" array of primitives, in
1265 // words.
1266 virtual size_t large_typearray_limit();
1268 // Returns "true" iff the given word_size is "very large".
1269 static bool isHumongous(size_t word_size) {
1270 // Note this has to be strictly greater-than as the TLABs
1271 // are capped at the humongous thresold and we want to
1272 // ensure that we don't try to allocate a TLAB as
1273 // humongous and that we don't allocate a humongous
1274 // object in a TLAB.
1275 return word_size > _humongous_object_threshold_in_words;
1276 }
1278 // Update mod union table with the set of dirty cards.
1279 void updateModUnion();
1281 // Set the mod union bits corresponding to the given memRegion. Note
1282 // that this is always a safe operation, since it doesn't clear any
1283 // bits.
1284 void markModUnionRange(MemRegion mr);
1286 // Records the fact that a marking phase is no longer in progress.
1287 void set_marking_complete() {
1288 _mark_in_progress = false;
1289 }
1290 void set_marking_started() {
1291 _mark_in_progress = true;
1292 }
1293 bool mark_in_progress() {
1294 return _mark_in_progress;
1295 }
1297 // Print the maximum heap capacity.
1298 virtual size_t max_capacity() const;
1300 virtual jlong millis_since_last_gc();
1302 // Perform any cleanup actions necessary before allowing a verification.
1303 virtual void prepare_for_verify();
1305 // Perform verification.
1307 // use_prev_marking == true -> use "prev" marking information,
1308 // use_prev_marking == false -> use "next" marking information
1309 // NOTE: Only the "prev" marking information is guaranteed to be
1310 // consistent most of the time, so most calls to this should use
1311 // use_prev_marking == true. Currently, there is only one case where
1312 // this is called with use_prev_marking == false, which is to verify
1313 // the "next" marking information at the end of remark.
1314 void verify(bool allow_dirty, bool silent, bool use_prev_marking);
1316 // Override; it uses the "prev" marking information
1317 virtual void verify(bool allow_dirty, bool silent);
1318 // Default behavior by calling print(tty);
1319 virtual void print() const;
1320 // This calls print_on(st, PrintHeapAtGCExtended).
1321 virtual void print_on(outputStream* st) const;
1322 // If extended is true, it will print out information for all
1323 // regions in the heap by calling print_on_extended(st).
1324 virtual void print_on(outputStream* st, bool extended) const;
1325 virtual void print_on_extended(outputStream* st) const;
1327 virtual void print_gc_threads_on(outputStream* st) const;
1328 virtual void gc_threads_do(ThreadClosure* tc) const;
1330 // Override
1331 void print_tracing_info() const;
1333 // If "addr" is a pointer into the (reserved?) heap, returns a positive
1334 // number indicating the "arena" within the heap in which "addr" falls.
1335 // Or else returns 0.
1336 virtual int addr_to_arena_id(void* addr) const;
1338 // Convenience function to be used in situations where the heap type can be
1339 // asserted to be this type.
1340 static G1CollectedHeap* heap();
1342 void empty_young_list();
1344 void set_region_short_lived_locked(HeapRegion* hr);
1345 // add appropriate methods for any other surv rate groups
1347 YoungList* young_list() { return _young_list; }
1349 // debugging
1350 bool check_young_list_well_formed() {
1351 return _young_list->check_list_well_formed();
1352 }
1354 bool check_young_list_empty(bool check_heap,
1355 bool check_sample = true);
1357 // *** Stuff related to concurrent marking. It's not clear to me that so
1358 // many of these need to be public.
1360 // The functions below are helper functions that a subclass of
1361 // "CollectedHeap" can use in the implementation of its virtual
1362 // functions.
1363 // This performs a concurrent marking of the live objects in a
1364 // bitmap off to the side.
1365 void doConcurrentMark();
1367 // This is called from the marksweep collector which then does
1368 // a concurrent mark and verifies that the results agree with
1369 // the stop the world marking.
1370 void checkConcurrentMark();
1371 void do_sync_mark();
1373 bool isMarkedPrev(oop obj) const;
1374 bool isMarkedNext(oop obj) const;
1376 // use_prev_marking == true -> use "prev" marking information,
1377 // use_prev_marking == false -> use "next" marking information
1378 bool is_obj_dead_cond(const oop obj,
1379 const HeapRegion* hr,
1380 const bool use_prev_marking) const {
1381 if (use_prev_marking) {
1382 return is_obj_dead(obj, hr);
1383 } else {
1384 return is_obj_ill(obj, hr);
1385 }
1386 }
1388 // Determine if an object is dead, given the object and also
1389 // the region to which the object belongs. An object is dead
1390 // iff a) it was not allocated since the last mark and b) it
1391 // is not marked.
1393 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1394 return
1395 !hr->obj_allocated_since_prev_marking(obj) &&
1396 !isMarkedPrev(obj);
1397 }
1399 // This is used when copying an object to survivor space.
1400 // If the object is marked live, then we mark the copy live.
1401 // If the object is allocated since the start of this mark
1402 // cycle, then we mark the copy live.
1403 // If the object has been around since the previous mark
1404 // phase, and hasn't been marked yet during this phase,
1405 // then we don't mark it, we just wait for the
1406 // current marking cycle to get to it.
1408 // This function returns true when an object has been
1409 // around since the previous marking and hasn't yet
1410 // been marked during this marking.
1412 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1413 return
1414 !hr->obj_allocated_since_next_marking(obj) &&
1415 !isMarkedNext(obj);
1416 }
1418 // Determine if an object is dead, given only the object itself.
1419 // This will find the region to which the object belongs and
1420 // then call the region version of the same function.
1422 // Added if it is in permanent gen it isn't dead.
1423 // Added if it is NULL it isn't dead.
1425 // use_prev_marking == true -> use "prev" marking information,
1426 // use_prev_marking == false -> use "next" marking information
1427 bool is_obj_dead_cond(const oop obj,
1428 const bool use_prev_marking) {
1429 if (use_prev_marking) {
1430 return is_obj_dead(obj);
1431 } else {
1432 return is_obj_ill(obj);
1433 }
1434 }
1436 bool is_obj_dead(const oop obj) {
1437 const HeapRegion* hr = heap_region_containing(obj);
1438 if (hr == NULL) {
1439 if (Universe::heap()->is_in_permanent(obj))
1440 return false;
1441 else if (obj == NULL) return false;
1442 else return true;
1443 }
1444 else return is_obj_dead(obj, hr);
1445 }
1447 bool is_obj_ill(const oop obj) {
1448 const HeapRegion* hr = heap_region_containing(obj);
1449 if (hr == NULL) {
1450 if (Universe::heap()->is_in_permanent(obj))
1451 return false;
1452 else if (obj == NULL) return false;
1453 else return true;
1454 }
1455 else return is_obj_ill(obj, hr);
1456 }
1458 // The following is just to alert the verification code
1459 // that a full collection has occurred and that the
1460 // remembered sets are no longer up to date.
1461 bool _full_collection;
1462 void set_full_collection() { _full_collection = true;}
1463 void clear_full_collection() {_full_collection = false;}
1464 bool full_collection() {return _full_collection;}
1466 ConcurrentMark* concurrent_mark() const { return _cm; }
1467 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1469 // The dirty cards region list is used to record a subset of regions
1470 // whose cards need clearing. The list if populated during the
1471 // remembered set scanning and drained during the card table
1472 // cleanup. Although the methods are reentrant, population/draining
1473 // phases must not overlap. For synchronization purposes the last
1474 // element on the list points to itself.
1475 HeapRegion* _dirty_cards_region_list;
1476 void push_dirty_cards_region(HeapRegion* hr);
1477 HeapRegion* pop_dirty_cards_region();
1479 public:
1480 void stop_conc_gc_threads();
1482 // <NEW PREDICTION>
1484 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1485 void check_if_region_is_too_expensive(double predicted_time_ms);
1486 size_t pending_card_num();
1487 size_t max_pending_card_num();
1488 size_t cards_scanned();
1490 // </NEW PREDICTION>
1492 protected:
1493 size_t _max_heap_capacity;
1494 };
1496 #define use_local_bitmaps 1
1497 #define verify_local_bitmaps 0
1498 #define oop_buffer_length 256
1500 #ifndef PRODUCT
1501 class GCLabBitMap;
1502 class GCLabBitMapClosure: public BitMapClosure {
1503 private:
1504 ConcurrentMark* _cm;
1505 GCLabBitMap* _bitmap;
1507 public:
1508 GCLabBitMapClosure(ConcurrentMark* cm,
1509 GCLabBitMap* bitmap) {
1510 _cm = cm;
1511 _bitmap = bitmap;
1512 }
1514 virtual bool do_bit(size_t offset);
1515 };
1516 #endif // !PRODUCT
1518 class GCLabBitMap: public BitMap {
1519 private:
1520 ConcurrentMark* _cm;
1522 int _shifter;
1523 size_t _bitmap_word_covers_words;
1525 // beginning of the heap
1526 HeapWord* _heap_start;
1528 // this is the actual start of the GCLab
1529 HeapWord* _real_start_word;
1531 // this is the actual end of the GCLab
1532 HeapWord* _real_end_word;
1534 // this is the first word, possibly located before the actual start
1535 // of the GCLab, that corresponds to the first bit of the bitmap
1536 HeapWord* _start_word;
1538 // size of a GCLab in words
1539 size_t _gclab_word_size;
1541 static int shifter() {
1542 return MinObjAlignment - 1;
1543 }
1545 // how many heap words does a single bitmap word corresponds to?
1546 static size_t bitmap_word_covers_words() {
1547 return BitsPerWord << shifter();
1548 }
1550 size_t gclab_word_size() const {
1551 return _gclab_word_size;
1552 }
1554 // Calculates actual GCLab size in words
1555 size_t gclab_real_word_size() const {
1556 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1557 / BitsPerWord;
1558 }
1560 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1561 size_t bits_in_bitmap = gclab_word_size >> shifter();
1562 // We are going to ensure that the beginning of a word in this
1563 // bitmap also corresponds to the beginning of a word in the
1564 // global marking bitmap. To handle the case where a GCLab
1565 // starts from the middle of the bitmap, we need to add enough
1566 // space (i.e. up to a bitmap word) to ensure that we have
1567 // enough bits in the bitmap.
1568 return bits_in_bitmap + BitsPerWord - 1;
1569 }
1570 public:
1571 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1572 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1573 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1574 _shifter(shifter()),
1575 _bitmap_word_covers_words(bitmap_word_covers_words()),
1576 _heap_start(heap_start),
1577 _gclab_word_size(gclab_word_size),
1578 _real_start_word(NULL),
1579 _real_end_word(NULL),
1580 _start_word(NULL)
1581 {
1582 guarantee( size_in_words() >= bitmap_size_in_words(),
1583 "just making sure");
1584 }
1586 inline unsigned heapWordToOffset(HeapWord* addr) {
1587 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1588 assert(offset < size(), "offset should be within bounds");
1589 return offset;
1590 }
1592 inline HeapWord* offsetToHeapWord(size_t offset) {
1593 HeapWord* addr = _start_word + (offset << _shifter);
1594 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1595 return addr;
1596 }
1598 bool fields_well_formed() {
1599 bool ret1 = (_real_start_word == NULL) &&
1600 (_real_end_word == NULL) &&
1601 (_start_word == NULL);
1602 if (ret1)
1603 return true;
1605 bool ret2 = _real_start_word >= _start_word &&
1606 _start_word < _real_end_word &&
1607 (_real_start_word + _gclab_word_size) == _real_end_word &&
1608 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1609 > _real_end_word;
1610 return ret2;
1611 }
1613 inline bool mark(HeapWord* addr) {
1614 guarantee(use_local_bitmaps, "invariant");
1615 assert(fields_well_formed(), "invariant");
1617 if (addr >= _real_start_word && addr < _real_end_word) {
1618 assert(!isMarked(addr), "should not have already been marked");
1620 // first mark it on the bitmap
1621 at_put(heapWordToOffset(addr), true);
1623 return true;
1624 } else {
1625 return false;
1626 }
1627 }
1629 inline bool isMarked(HeapWord* addr) {
1630 guarantee(use_local_bitmaps, "invariant");
1631 assert(fields_well_formed(), "invariant");
1633 return at(heapWordToOffset(addr));
1634 }
1636 void set_buffer(HeapWord* start) {
1637 guarantee(use_local_bitmaps, "invariant");
1638 clear();
1640 assert(start != NULL, "invariant");
1641 _real_start_word = start;
1642 _real_end_word = start + _gclab_word_size;
1644 size_t diff =
1645 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1646 _start_word = start - diff;
1648 assert(fields_well_formed(), "invariant");
1649 }
1651 #ifndef PRODUCT
1652 void verify() {
1653 // verify that the marks have been propagated
1654 GCLabBitMapClosure cl(_cm, this);
1655 iterate(&cl);
1656 }
1657 #endif // PRODUCT
1659 void retire() {
1660 guarantee(use_local_bitmaps, "invariant");
1661 assert(fields_well_formed(), "invariant");
1663 if (_start_word != NULL) {
1664 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1666 // this means that the bitmap was set up for the GCLab
1667 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1669 mark_bitmap->mostly_disjoint_range_union(this,
1670 0, // always start from the start of the bitmap
1671 _start_word,
1672 gclab_real_word_size());
1673 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1675 #ifndef PRODUCT
1676 if (use_local_bitmaps && verify_local_bitmaps)
1677 verify();
1678 #endif // PRODUCT
1679 } else {
1680 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1681 }
1682 }
1684 size_t bitmap_size_in_words() const {
1685 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1686 }
1688 };
1690 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1691 private:
1692 bool _retired;
1693 bool _during_marking;
1694 GCLabBitMap _bitmap;
1696 public:
1697 G1ParGCAllocBuffer(size_t gclab_word_size) :
1698 ParGCAllocBuffer(gclab_word_size),
1699 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1700 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1701 _retired(false)
1702 { }
1704 inline bool mark(HeapWord* addr) {
1705 guarantee(use_local_bitmaps, "invariant");
1706 assert(_during_marking, "invariant");
1707 return _bitmap.mark(addr);
1708 }
1710 inline void set_buf(HeapWord* buf) {
1711 if (use_local_bitmaps && _during_marking)
1712 _bitmap.set_buffer(buf);
1713 ParGCAllocBuffer::set_buf(buf);
1714 _retired = false;
1715 }
1717 inline void retire(bool end_of_gc, bool retain) {
1718 if (_retired)
1719 return;
1720 if (use_local_bitmaps && _during_marking) {
1721 _bitmap.retire();
1722 }
1723 ParGCAllocBuffer::retire(end_of_gc, retain);
1724 _retired = true;
1725 }
1726 };
1728 class G1ParScanThreadState : public StackObj {
1729 protected:
1730 G1CollectedHeap* _g1h;
1731 RefToScanQueue* _refs;
1732 DirtyCardQueue _dcq;
1733 CardTableModRefBS* _ct_bs;
1734 G1RemSet* _g1_rem;
1736 G1ParGCAllocBuffer _surviving_alloc_buffer;
1737 G1ParGCAllocBuffer _tenured_alloc_buffer;
1738 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1739 ageTable _age_table;
1741 size_t _alloc_buffer_waste;
1742 size_t _undo_waste;
1744 OopsInHeapRegionClosure* _evac_failure_cl;
1745 G1ParScanHeapEvacClosure* _evac_cl;
1746 G1ParScanPartialArrayClosure* _partial_scan_cl;
1748 int _hash_seed;
1749 int _queue_num;
1751 size_t _term_attempts;
1753 double _start;
1754 double _start_strong_roots;
1755 double _strong_roots_time;
1756 double _start_term;
1757 double _term_time;
1759 // Map from young-age-index (0 == not young, 1 is youngest) to
1760 // surviving words. base is what we get back from the malloc call
1761 size_t* _surviving_young_words_base;
1762 // this points into the array, as we use the first few entries for padding
1763 size_t* _surviving_young_words;
1765 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1767 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1769 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1771 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1772 CardTableModRefBS* ctbs() { return _ct_bs; }
1774 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1775 if (!from->is_survivor()) {
1776 _g1_rem->par_write_ref(from, p, tid);
1777 }
1778 }
1780 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1781 // If the new value of the field points to the same region or
1782 // is the to-space, we don't need to include it in the Rset updates.
1783 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1784 size_t card_index = ctbs()->index_for(p);
1785 // If the card hasn't been added to the buffer, do it.
1786 if (ctbs()->mark_card_deferred(card_index)) {
1787 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1788 }
1789 }
1790 }
1792 public:
1793 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1795 ~G1ParScanThreadState() {
1796 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1797 }
1799 RefToScanQueue* refs() { return _refs; }
1800 ageTable* age_table() { return &_age_table; }
1802 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1803 return _alloc_buffers[purpose];
1804 }
1806 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1807 size_t undo_waste() const { return _undo_waste; }
1809 #ifdef ASSERT
1810 bool verify_ref(narrowOop* ref) const;
1811 bool verify_ref(oop* ref) const;
1812 bool verify_task(StarTask ref) const;
1813 #endif // ASSERT
1815 template <class T> void push_on_queue(T* ref) {
1816 assert(verify_ref(ref), "sanity");
1817 refs()->push(ref);
1818 }
1820 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1821 if (G1DeferredRSUpdate) {
1822 deferred_rs_update(from, p, tid);
1823 } else {
1824 immediate_rs_update(from, p, tid);
1825 }
1826 }
1828 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1830 HeapWord* obj = NULL;
1831 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1832 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1833 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1834 assert(gclab_word_size == alloc_buf->word_sz(),
1835 "dynamic resizing is not supported");
1836 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1837 alloc_buf->retire(false, false);
1839 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1840 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1841 // Otherwise.
1842 alloc_buf->set_buf(buf);
1844 obj = alloc_buf->allocate(word_sz);
1845 assert(obj != NULL, "buffer was definitely big enough...");
1846 } else {
1847 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1848 }
1849 return obj;
1850 }
1852 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1853 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1854 if (obj != NULL) return obj;
1855 return allocate_slow(purpose, word_sz);
1856 }
1858 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1859 if (alloc_buffer(purpose)->contains(obj)) {
1860 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1861 "should contain whole object");
1862 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1863 } else {
1864 CollectedHeap::fill_with_object(obj, word_sz);
1865 add_to_undo_waste(word_sz);
1866 }
1867 }
1869 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1870 _evac_failure_cl = evac_failure_cl;
1871 }
1872 OopsInHeapRegionClosure* evac_failure_closure() {
1873 return _evac_failure_cl;
1874 }
1876 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1877 _evac_cl = evac_cl;
1878 }
1880 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1881 _partial_scan_cl = partial_scan_cl;
1882 }
1884 int* hash_seed() { return &_hash_seed; }
1885 int queue_num() { return _queue_num; }
1887 size_t term_attempts() const { return _term_attempts; }
1888 void note_term_attempt() { _term_attempts++; }
1890 void start_strong_roots() {
1891 _start_strong_roots = os::elapsedTime();
1892 }
1893 void end_strong_roots() {
1894 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1895 }
1896 double strong_roots_time() const { return _strong_roots_time; }
1898 void start_term_time() {
1899 note_term_attempt();
1900 _start_term = os::elapsedTime();
1901 }
1902 void end_term_time() {
1903 _term_time += (os::elapsedTime() - _start_term);
1904 }
1905 double term_time() const { return _term_time; }
1907 double elapsed_time() const {
1908 return os::elapsedTime() - _start;
1909 }
1911 static void
1912 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1913 void
1914 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1916 size_t* surviving_young_words() {
1917 // We add on to hide entry 0 which accumulates surviving words for
1918 // age -1 regions (i.e. non-young ones)
1919 return _surviving_young_words;
1920 }
1922 void retire_alloc_buffers() {
1923 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1924 size_t waste = _alloc_buffers[ap]->words_remaining();
1925 add_to_alloc_buffer_waste(waste);
1926 _alloc_buffers[ap]->retire(true, false);
1927 }
1928 }
1930 template <class T> void deal_with_reference(T* ref_to_scan) {
1931 if (has_partial_array_mask(ref_to_scan)) {
1932 _partial_scan_cl->do_oop_nv(ref_to_scan);
1933 } else {
1934 // Note: we can use "raw" versions of "region_containing" because
1935 // "obj_to_scan" is definitely in the heap, and is not in a
1936 // humongous region.
1937 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1938 _evac_cl->set_region(r);
1939 _evac_cl->do_oop_nv(ref_to_scan);
1940 }
1941 }
1943 void deal_with_reference(StarTask ref) {
1944 assert(verify_task(ref), "sanity");
1945 if (ref.is_narrow()) {
1946 deal_with_reference((narrowOop*)ref);
1947 } else {
1948 deal_with_reference((oop*)ref);
1949 }
1950 }
1952 public:
1953 void trim_queue();
1954 };
1956 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP