Tue, 20 Sep 2011 15:39:17 -0700
7092412: G1: Some roots not marked during an initial mark that gets an evacuation failure
Summary: As a result of the changes for 7080389, an evacuation failure during an initial mark pause may result in some root objects not being marked. Pass whether the caller is a root scanning closure into the evacuation failure handling code so that the thread that successfully forwards an object to itself also marks the object.
Reviewed-by: ysr, brutisso, tonyp
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/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
65 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
77 class YoungList : public CHeapObj {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 size_t _length;
89 size_t _survivor_length;
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
94 void empty_list(HeapRegion* list);
96 public:
97 YoungList(G1CollectedHeap* g1h);
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 size_t length() { return _length; }
105 size_t survivor_length() { return _survivor_length; }
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return survivor_length() * HeapRegion::GrainBytes;
118 }
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
156 };
158 class SurvivorGCAllocRegion : public G1AllocRegion {
159 protected:
160 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
161 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
162 public:
163 SurvivorGCAllocRegion()
164 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
165 };
167 class OldGCAllocRegion : public G1AllocRegion {
168 protected:
169 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
170 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
171 public:
172 OldGCAllocRegion()
173 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
174 };
176 class RefineCardTableEntryClosure;
177 class G1CollectedHeap : public SharedHeap {
178 friend class VM_G1CollectForAllocation;
179 friend class VM_GenCollectForPermanentAllocation;
180 friend class VM_G1CollectFull;
181 friend class VM_G1IncCollectionPause;
182 friend class VMStructs;
183 friend class MutatorAllocRegion;
184 friend class SurvivorGCAllocRegion;
185 friend class OldGCAllocRegion;
187 // Closures used in implementation.
188 friend class G1ParCopyHelper;
189 friend class G1IsAliveClosure;
190 friend class G1EvacuateFollowersClosure;
191 friend class G1ParScanThreadState;
192 friend class G1ParScanClosureSuper;
193 friend class G1ParEvacuateFollowersClosure;
194 friend class G1ParTask;
195 friend class G1FreeGarbageRegionClosure;
196 friend class RefineCardTableEntryClosure;
197 friend class G1PrepareCompactClosure;
198 friend class RegionSorter;
199 friend class RegionResetter;
200 friend class CountRCClosure;
201 friend class EvacPopObjClosure;
202 friend class G1ParCleanupCTTask;
204 // Other related classes.
205 friend class G1MarkSweep;
207 private:
208 // The one and only G1CollectedHeap, so static functions can find it.
209 static G1CollectedHeap* _g1h;
211 static size_t _humongous_object_threshold_in_words;
213 // Storage for the G1 heap (excludes the permanent generation).
214 VirtualSpace _g1_storage;
215 MemRegion _g1_reserved;
217 // The part of _g1_storage that is currently committed.
218 MemRegion _g1_committed;
220 // The master free list. It will satisfy all new region allocations.
221 MasterFreeRegionList _free_list;
223 // The secondary free list which contains regions that have been
224 // freed up during the cleanup process. This will be appended to the
225 // master free list when appropriate.
226 SecondaryFreeRegionList _secondary_free_list;
228 // It keeps track of the humongous regions.
229 MasterHumongousRegionSet _humongous_set;
231 // The number of regions we could create by expansion.
232 size_t _expansion_regions;
234 // The block offset table for the G1 heap.
235 G1BlockOffsetSharedArray* _bot_shared;
237 // Move all of the regions off the free lists, then rebuild those free
238 // lists, before and after full GC.
239 void tear_down_region_lists();
240 void rebuild_region_lists();
242 // The sequence of all heap regions in the heap.
243 HeapRegionSeq _hrs;
245 // Alloc region used to satisfy mutator allocation requests.
246 MutatorAllocRegion _mutator_alloc_region;
248 // Alloc region used to satisfy allocation requests by the GC for
249 // survivor objects.
250 SurvivorGCAllocRegion _survivor_gc_alloc_region;
252 // Alloc region used to satisfy allocation requests by the GC for
253 // old objects.
254 OldGCAllocRegion _old_gc_alloc_region;
256 // The last old region we allocated to during the last GC.
257 // Typically, it is not full so we should re-use it during the next GC.
258 HeapRegion* _retained_old_gc_alloc_region;
260 // It resets the mutator alloc region before new allocations can take place.
261 void init_mutator_alloc_region();
263 // It releases the mutator alloc region.
264 void release_mutator_alloc_region();
266 // It initializes the GC alloc regions at the start of a GC.
267 void init_gc_alloc_regions();
269 // It releases the GC alloc regions at the end of a GC.
270 void release_gc_alloc_regions();
272 // It does any cleanup that needs to be done on the GC alloc regions
273 // before a Full GC.
274 void abandon_gc_alloc_regions();
276 // Helper for monitoring and management support.
277 G1MonitoringSupport* _g1mm;
279 // Determines PLAB size for a particular allocation purpose.
280 static size_t desired_plab_sz(GCAllocPurpose purpose);
282 // Outside of GC pauses, the number of bytes used in all regions other
283 // than the current allocation region.
284 size_t _summary_bytes_used;
286 // This is used for a quick test on whether a reference points into
287 // the collection set or not. Basically, we have an array, with one
288 // byte per region, and that byte denotes whether the corresponding
289 // region is in the collection set or not. The entry corresponding
290 // the bottom of the heap, i.e., region 0, is pointed to by
291 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
292 // biased so that it actually points to address 0 of the address
293 // space, to make the test as fast as possible (we can simply shift
294 // the address to address into it, instead of having to subtract the
295 // bottom of the heap from the address before shifting it; basically
296 // it works in the same way the card table works).
297 bool* _in_cset_fast_test;
299 // The allocated array used for the fast test on whether a reference
300 // points into the collection set or not. This field is also used to
301 // free the array.
302 bool* _in_cset_fast_test_base;
304 // The length of the _in_cset_fast_test_base array.
305 size_t _in_cset_fast_test_length;
307 volatile unsigned _gc_time_stamp;
309 size_t* _surviving_young_words;
311 G1HRPrinter _hr_printer;
313 void setup_surviving_young_words();
314 void update_surviving_young_words(size_t* surv_young_words);
315 void cleanup_surviving_young_words();
317 // It decides whether an explicit GC should start a concurrent cycle
318 // instead of doing a STW GC. Currently, a concurrent cycle is
319 // explicitly started if:
320 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
321 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
322 bool should_do_concurrent_full_gc(GCCause::Cause cause);
324 // Keeps track of how many "full collections" (i.e., Full GCs or
325 // concurrent cycles) we have completed. The number of them we have
326 // started is maintained in _total_full_collections in CollectedHeap.
327 volatile unsigned int _full_collections_completed;
329 // This is a non-product method that is helpful for testing. It is
330 // called at the end of a GC and artificially expands the heap by
331 // allocating a number of dead regions. This way we can induce very
332 // frequent marking cycles and stress the cleanup / concurrent
333 // cleanup code more (as all the regions that will be allocated by
334 // this method will be found dead by the marking cycle).
335 void allocate_dummy_regions() PRODUCT_RETURN;
337 // These are macros so that, if the assert fires, we get the correct
338 // line number, file, etc.
340 #define heap_locking_asserts_err_msg(_extra_message_) \
341 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
342 (_extra_message_), \
343 BOOL_TO_STR(Heap_lock->owned_by_self()), \
344 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
345 BOOL_TO_STR(Thread::current()->is_VM_thread()))
347 #define assert_heap_locked() \
348 do { \
349 assert(Heap_lock->owned_by_self(), \
350 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
351 } while (0)
353 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
354 do { \
355 assert(Heap_lock->owned_by_self() || \
356 (SafepointSynchronize::is_at_safepoint() && \
357 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
358 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
359 "should be at a safepoint")); \
360 } while (0)
362 #define assert_heap_locked_and_not_at_safepoint() \
363 do { \
364 assert(Heap_lock->owned_by_self() && \
365 !SafepointSynchronize::is_at_safepoint(), \
366 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
367 "should not be at a safepoint")); \
368 } while (0)
370 #define assert_heap_not_locked() \
371 do { \
372 assert(!Heap_lock->owned_by_self(), \
373 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
374 } while (0)
376 #define assert_heap_not_locked_and_not_at_safepoint() \
377 do { \
378 assert(!Heap_lock->owned_by_self() && \
379 !SafepointSynchronize::is_at_safepoint(), \
380 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
381 "should not be at a safepoint")); \
382 } while (0)
384 #define assert_at_safepoint(_should_be_vm_thread_) \
385 do { \
386 assert(SafepointSynchronize::is_at_safepoint() && \
387 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
388 heap_locking_asserts_err_msg("should be at a safepoint")); \
389 } while (0)
391 #define assert_not_at_safepoint() \
392 do { \
393 assert(!SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should not be at a safepoint")); \
395 } while (0)
397 protected:
399 // The young region list.
400 YoungList* _young_list;
402 // The current policy object for the collector.
403 G1CollectorPolicy* _g1_policy;
405 // This is the second level of trying to allocate a new region. If
406 // new_region() didn't find a region on the free_list, this call will
407 // check whether there's anything available on the
408 // secondary_free_list and/or wait for more regions to appear on
409 // that list, if _free_regions_coming is set.
410 HeapRegion* new_region_try_secondary_free_list();
412 // Try to allocate a single non-humongous HeapRegion sufficient for
413 // an allocation of the given word_size. If do_expand is true,
414 // attempt to expand the heap if necessary to satisfy the allocation
415 // request.
416 HeapRegion* new_region(size_t word_size, bool do_expand);
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 // Allocation attempt during GC for a survivor object / PLAB.
526 inline HeapWord* survivor_attempt_allocation(size_t word_size);
528 // Allocation attempt during GC for an old object / PLAB.
529 inline HeapWord* old_attempt_allocation(size_t word_size);
531 // These methods are the "callbacks" from the G1AllocRegion class.
533 // For mutator alloc regions.
534 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
535 void retire_mutator_alloc_region(HeapRegion* alloc_region,
536 size_t allocated_bytes);
538 // For GC alloc regions.
539 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
540 GCAllocPurpose ap);
541 void retire_gc_alloc_region(HeapRegion* alloc_region,
542 size_t allocated_bytes, GCAllocPurpose ap);
544 // - if explicit_gc is true, the GC is for a System.gc() or a heap
545 // inspection request and should collect the entire heap
546 // - if clear_all_soft_refs is true, all soft references should be
547 // cleared during the GC
548 // - if explicit_gc is false, word_size describes the allocation that
549 // the GC should attempt (at least) to satisfy
550 // - it returns false if it is unable to do the collection due to the
551 // GC locker being active, true otherwise
552 bool do_collection(bool explicit_gc,
553 bool clear_all_soft_refs,
554 size_t word_size);
556 // Callback from VM_G1CollectFull operation.
557 // Perform a full collection.
558 void do_full_collection(bool clear_all_soft_refs);
560 // Resize the heap if necessary after a full collection. If this is
561 // after a collect-for allocation, "word_size" is the allocation size,
562 // and will be considered part of the used portion of the heap.
563 void resize_if_necessary_after_full_collection(size_t word_size);
565 // Callback from VM_G1CollectForAllocation operation.
566 // This function does everything necessary/possible to satisfy a
567 // failed allocation request (including collection, expansion, etc.)
568 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
570 // Attempting to expand the heap sufficiently
571 // to support an allocation of the given "word_size". If
572 // successful, perform the allocation and return the address of the
573 // allocated block, or else "NULL".
574 HeapWord* expand_and_allocate(size_t word_size);
576 public:
578 G1MonitoringSupport* g1mm() { return _g1mm; }
580 // Expand the garbage-first heap by at least the given size (in bytes!).
581 // Returns true if the heap was expanded by the requested amount;
582 // false otherwise.
583 // (Rounds up to a HeapRegion boundary.)
584 bool expand(size_t expand_bytes);
586 // Do anything common to GC's.
587 virtual void gc_prologue(bool full);
588 virtual void gc_epilogue(bool full);
590 // We register a region with the fast "in collection set" test. We
591 // simply set to true the array slot corresponding to this region.
592 void register_region_with_in_cset_fast_test(HeapRegion* r) {
593 assert(_in_cset_fast_test_base != NULL, "sanity");
594 assert(r->in_collection_set(), "invariant");
595 size_t index = r->hrs_index();
596 assert(index < _in_cset_fast_test_length, "invariant");
597 assert(!_in_cset_fast_test_base[index], "invariant");
598 _in_cset_fast_test_base[index] = true;
599 }
601 // This is a fast test on whether a reference points into the
602 // collection set or not. It does not assume that the reference
603 // points into the heap; if it doesn't, it will return false.
604 bool in_cset_fast_test(oop obj) {
605 assert(_in_cset_fast_test != NULL, "sanity");
606 if (_g1_committed.contains((HeapWord*) obj)) {
607 // no need to subtract the bottom of the heap from obj,
608 // _in_cset_fast_test is biased
609 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
610 bool ret = _in_cset_fast_test[index];
611 // let's make sure the result is consistent with what the slower
612 // test returns
613 assert( ret || !obj_in_cs(obj), "sanity");
614 assert(!ret || obj_in_cs(obj), "sanity");
615 return ret;
616 } else {
617 return false;
618 }
619 }
621 void clear_cset_fast_test() {
622 assert(_in_cset_fast_test_base != NULL, "sanity");
623 memset(_in_cset_fast_test_base, false,
624 _in_cset_fast_test_length * sizeof(bool));
625 }
627 // This is called at the end of either a concurrent cycle or a Full
628 // GC to update the number of full collections completed. Those two
629 // can happen in a nested fashion, i.e., we start a concurrent
630 // cycle, a Full GC happens half-way through it which ends first,
631 // and then the cycle notices that a Full GC happened and ends
632 // too. The concurrent parameter is a boolean to help us do a bit
633 // tighter consistency checking in the method. If concurrent is
634 // false, the caller is the inner caller in the nesting (i.e., the
635 // Full GC). If concurrent is true, the caller is the outer caller
636 // in this nesting (i.e., the concurrent cycle). Further nesting is
637 // not currently supported. The end of the this call also notifies
638 // the FullGCCount_lock in case a Java thread is waiting for a full
639 // GC to happen (e.g., it called System.gc() with
640 // +ExplicitGCInvokesConcurrent).
641 void increment_full_collections_completed(bool concurrent);
643 unsigned int full_collections_completed() {
644 return _full_collections_completed;
645 }
647 G1HRPrinter* hr_printer() { return &_hr_printer; }
649 protected:
651 // Shrink the garbage-first heap by at most the given size (in bytes!).
652 // (Rounds down to a HeapRegion boundary.)
653 virtual void shrink(size_t expand_bytes);
654 void shrink_helper(size_t expand_bytes);
656 #if TASKQUEUE_STATS
657 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
658 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
659 void reset_taskqueue_stats();
660 #endif // TASKQUEUE_STATS
662 // Schedule the VM operation that will do an evacuation pause to
663 // satisfy an allocation request of word_size. *succeeded will
664 // return whether the VM operation was successful (it did do an
665 // evacuation pause) or not (another thread beat us to it or the GC
666 // locker was active). Given that we should not be holding the
667 // Heap_lock when we enter this method, we will pass the
668 // gc_count_before (i.e., total_collections()) as a parameter since
669 // it has to be read while holding the Heap_lock. Currently, both
670 // methods that call do_collection_pause() release the Heap_lock
671 // before the call, so it's easy to read gc_count_before just before.
672 HeapWord* do_collection_pause(size_t word_size,
673 unsigned int gc_count_before,
674 bool* succeeded);
676 // The guts of the incremental collection pause, executed by the vm
677 // thread. It returns false if it is unable to do the collection due
678 // to the GC locker being active, true otherwise
679 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
681 // Actually do the work of evacuating the collection set.
682 void evacuate_collection_set();
684 // The g1 remembered set of the heap.
685 G1RemSet* _g1_rem_set;
686 // And it's mod ref barrier set, used to track updates for the above.
687 ModRefBarrierSet* _mr_bs;
689 // A set of cards that cover the objects for which the Rsets should be updated
690 // concurrently after the collection.
691 DirtyCardQueueSet _dirty_card_queue_set;
693 // The Heap Region Rem Set Iterator.
694 HeapRegionRemSetIterator** _rem_set_iterator;
696 // The closure used to refine a single card.
697 RefineCardTableEntryClosure* _refine_cte_cl;
699 // A function to check the consistency of dirty card logs.
700 void check_ct_logs_at_safepoint();
702 // A DirtyCardQueueSet that is used to hold cards that contain
703 // references into the current collection set. This is used to
704 // update the remembered sets of the regions in the collection
705 // set in the event of an evacuation failure.
706 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
708 // After a collection pause, make the regions in the CS into free
709 // regions.
710 void free_collection_set(HeapRegion* cs_head);
712 // Abandon the current collection set without recording policy
713 // statistics or updating free lists.
714 void abandon_collection_set(HeapRegion* cs_head);
716 // Applies "scan_non_heap_roots" to roots outside the heap,
717 // "scan_rs" to roots inside the heap (having done "set_region" to
718 // indicate the region in which the root resides), and does "scan_perm"
719 // (setting the generation to the perm generation.) If "scan_rs" is
720 // NULL, then this step is skipped. The "worker_i"
721 // param is for use with parallel roots processing, and should be
722 // the "i" of the calling parallel worker thread's work(i) function.
723 // In the sequential case this param will be ignored.
724 void g1_process_strong_roots(bool collecting_perm_gen,
725 SharedHeap::ScanningOption so,
726 OopClosure* scan_non_heap_roots,
727 OopsInHeapRegionClosure* scan_rs,
728 OopsInGenClosure* scan_perm,
729 int worker_i);
731 // Apply "blk" to all the weak roots of the system. These include
732 // JNI weak roots, the code cache, system dictionary, symbol table,
733 // string table, and referents of reachable weak refs.
734 void g1_process_weak_roots(OopClosure* root_closure,
735 OopClosure* non_root_closure);
737 // Frees a non-humongous region by initializing its contents and
738 // adding it to the free list that's passed as a parameter (this is
739 // usually a local list which will be appended to the master free
740 // list later). The used bytes of freed regions are accumulated in
741 // pre_used. If par is true, the region's RSet will not be freed
742 // up. The assumption is that this will be done later.
743 void free_region(HeapRegion* hr,
744 size_t* pre_used,
745 FreeRegionList* free_list,
746 bool par);
748 // Frees a humongous region by collapsing it into individual regions
749 // and calling free_region() for each of them. The freed regions
750 // will be added to the free list that's passed as a parameter (this
751 // is usually a local list which will be appended to the master free
752 // list later). The used bytes of freed regions are accumulated in
753 // pre_used. If par is true, the region's RSet will not be freed
754 // up. The assumption is that this will be done later.
755 void free_humongous_region(HeapRegion* hr,
756 size_t* pre_used,
757 FreeRegionList* free_list,
758 HumongousRegionSet* humongous_proxy_set,
759 bool par);
761 // Notifies all the necessary spaces that the committed space has
762 // been updated (either expanded or shrunk). It should be called
763 // after _g1_storage is updated.
764 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
766 // The concurrent marker (and the thread it runs in.)
767 ConcurrentMark* _cm;
768 ConcurrentMarkThread* _cmThread;
769 bool _mark_in_progress;
771 // The concurrent refiner.
772 ConcurrentG1Refine* _cg1r;
774 // The parallel task queues
775 RefToScanQueueSet *_task_queues;
777 // True iff a evacuation has failed in the current collection.
778 bool _evacuation_failed;
780 // Set the attribute indicating whether evacuation has failed in the
781 // current collection.
782 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
784 // Failed evacuations cause some logical from-space objects to have
785 // forwarding pointers to themselves. Reset them.
786 void remove_self_forwarding_pointers();
788 // When one is non-null, so is the other. Together, they each pair is
789 // an object with a preserved mark, and its mark value.
790 GrowableArray<oop>* _objs_with_preserved_marks;
791 GrowableArray<markOop>* _preserved_marks_of_objs;
793 // Preserve the mark of "obj", if necessary, in preparation for its mark
794 // word being overwritten with a self-forwarding-pointer.
795 void preserve_mark_if_necessary(oop obj, markOop m);
797 // The stack of evac-failure objects left to be scanned.
798 GrowableArray<oop>* _evac_failure_scan_stack;
799 // The closure to apply to evac-failure objects.
801 OopsInHeapRegionClosure* _evac_failure_closure;
802 // Set the field above.
803 void
804 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
805 _evac_failure_closure = evac_failure_closure;
806 }
808 // Push "obj" on the scan stack.
809 void push_on_evac_failure_scan_stack(oop obj);
810 // Process scan stack entries until the stack is empty.
811 void drain_evac_failure_scan_stack();
812 // True iff an invocation of "drain_scan_stack" is in progress; to
813 // prevent unnecessary recursion.
814 bool _drain_in_progress;
816 // Do any necessary initialization for evacuation-failure handling.
817 // "cl" is the closure that will be used to process evac-failure
818 // objects.
819 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
820 // Do any necessary cleanup for evacuation-failure handling data
821 // structures.
822 void finalize_for_evac_failure();
824 // An attempt to evacuate "obj" has failed; take necessary steps.
825 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj,
826 bool should_mark_root);
827 void handle_evacuation_failure_common(oop obj, markOop m);
829 // Instance of the concurrent mark is_alive closure for embedding
830 // into the reference processor as the is_alive_non_header. This
831 // prevents unnecessary additions to the discovered lists during
832 // concurrent discovery.
833 G1CMIsAliveClosure _is_alive_closure;
835 // ("Weak") Reference processing support
836 ReferenceProcessor* _ref_processor;
838 enum G1H_process_strong_roots_tasks {
839 G1H_PS_mark_stack_oops_do,
840 G1H_PS_refProcessor_oops_do,
841 // Leave this one last.
842 G1H_PS_NumElements
843 };
845 SubTasksDone* _process_strong_tasks;
847 volatile bool _free_regions_coming;
849 public:
851 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
853 void set_refine_cte_cl_concurrency(bool concurrent);
855 RefToScanQueue *task_queue(int i) const;
857 // A set of cards where updates happened during the GC
858 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
860 // A DirtyCardQueueSet that is used to hold cards that contain
861 // references into the current collection set. This is used to
862 // update the remembered sets of the regions in the collection
863 // set in the event of an evacuation failure.
864 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
865 { return _into_cset_dirty_card_queue_set; }
867 // Create a G1CollectedHeap with the specified policy.
868 // Must call the initialize method afterwards.
869 // May not return if something goes wrong.
870 G1CollectedHeap(G1CollectorPolicy* policy);
872 // Initialize the G1CollectedHeap to have the initial and
873 // maximum sizes, permanent generation, and remembered and barrier sets
874 // specified by the policy object.
875 jint initialize();
877 virtual void ref_processing_init();
879 void set_par_threads(int t) {
880 SharedHeap::set_par_threads(t);
881 _process_strong_tasks->set_n_threads(t);
882 }
884 virtual CollectedHeap::Name kind() const {
885 return CollectedHeap::G1CollectedHeap;
886 }
888 // The current policy object for the collector.
889 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
891 // Adaptive size policy. No such thing for g1.
892 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
894 // The rem set and barrier set.
895 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
896 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
898 // The rem set iterator.
899 HeapRegionRemSetIterator* rem_set_iterator(int i) {
900 return _rem_set_iterator[i];
901 }
903 HeapRegionRemSetIterator* rem_set_iterator() {
904 return _rem_set_iterator[0];
905 }
907 unsigned get_gc_time_stamp() {
908 return _gc_time_stamp;
909 }
911 void reset_gc_time_stamp() {
912 _gc_time_stamp = 0;
913 OrderAccess::fence();
914 }
916 void increment_gc_time_stamp() {
917 ++_gc_time_stamp;
918 OrderAccess::fence();
919 }
921 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
922 DirtyCardQueue* into_cset_dcq,
923 bool concurrent, int worker_i);
925 // The shared block offset table array.
926 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
928 // Reference Processing accessor
929 ReferenceProcessor* ref_processor() { return _ref_processor; }
931 virtual size_t capacity() const;
932 virtual size_t used() const;
933 // This should be called when we're not holding the heap lock. The
934 // result might be a bit inaccurate.
935 size_t used_unlocked() const;
936 size_t recalculate_used() const;
938 // These virtual functions do the actual allocation.
939 // Some heaps may offer a contiguous region for shared non-blocking
940 // allocation, via inlined code (by exporting the address of the top and
941 // end fields defining the extent of the contiguous allocation region.)
942 // But G1CollectedHeap doesn't yet support this.
944 // Return an estimate of the maximum allocation that could be performed
945 // without triggering any collection or expansion activity. In a
946 // generational collector, for example, this is probably the largest
947 // allocation that could be supported (without expansion) in the youngest
948 // generation. It is "unsafe" because no locks are taken; the result
949 // should be treated as an approximation, not a guarantee, for use in
950 // heuristic resizing decisions.
951 virtual size_t unsafe_max_alloc();
953 virtual bool is_maximal_no_gc() const {
954 return _g1_storage.uncommitted_size() == 0;
955 }
957 // The total number of regions in the heap.
958 size_t n_regions() { return _hrs.length(); }
960 // The max number of regions in the heap.
961 size_t max_regions() { return _hrs.max_length(); }
963 // The number of regions that are completely free.
964 size_t free_regions() { return _free_list.length(); }
966 // The number of regions that are not completely free.
967 size_t used_regions() { return n_regions() - free_regions(); }
969 // The number of regions available for "regular" expansion.
970 size_t expansion_regions() { return _expansion_regions; }
972 // Factory method for HeapRegion instances. It will return NULL if
973 // the allocation fails.
974 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
976 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
977 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
978 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
979 void verify_dirty_young_regions() PRODUCT_RETURN;
981 // verify_region_sets() performs verification over the region
982 // lists. It will be compiled in the product code to be used when
983 // necessary (i.e., during heap verification).
984 void verify_region_sets();
986 // verify_region_sets_optional() is planted in the code for
987 // list verification in non-product builds (and it can be enabled in
988 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
989 #if HEAP_REGION_SET_FORCE_VERIFY
990 void verify_region_sets_optional() {
991 verify_region_sets();
992 }
993 #else // HEAP_REGION_SET_FORCE_VERIFY
994 void verify_region_sets_optional() { }
995 #endif // HEAP_REGION_SET_FORCE_VERIFY
997 #ifdef ASSERT
998 bool is_on_master_free_list(HeapRegion* hr) {
999 return hr->containing_set() == &_free_list;
1000 }
1002 bool is_in_humongous_set(HeapRegion* hr) {
1003 return hr->containing_set() == &_humongous_set;
1004 }
1005 #endif // ASSERT
1007 // Wrapper for the region list operations that can be called from
1008 // methods outside this class.
1010 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1011 _secondary_free_list.add_as_tail(list);
1012 }
1014 void append_secondary_free_list() {
1015 _free_list.add_as_head(&_secondary_free_list);
1016 }
1018 void append_secondary_free_list_if_not_empty_with_lock() {
1019 // If the secondary free list looks empty there's no reason to
1020 // take the lock and then try to append it.
1021 if (!_secondary_free_list.is_empty()) {
1022 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1023 append_secondary_free_list();
1024 }
1025 }
1027 void set_free_regions_coming();
1028 void reset_free_regions_coming();
1029 bool free_regions_coming() { return _free_regions_coming; }
1030 void wait_while_free_regions_coming();
1032 // Perform a collection of the heap; intended for use in implementing
1033 // "System.gc". This probably implies as full a collection as the
1034 // "CollectedHeap" supports.
1035 virtual void collect(GCCause::Cause cause);
1037 // The same as above but assume that the caller holds the Heap_lock.
1038 void collect_locked(GCCause::Cause cause);
1040 // This interface assumes that it's being called by the
1041 // vm thread. It collects the heap assuming that the
1042 // heap lock is already held and that we are executing in
1043 // the context of the vm thread.
1044 virtual void collect_as_vm_thread(GCCause::Cause cause);
1046 // True iff a evacuation has failed in the most-recent collection.
1047 bool evacuation_failed() { return _evacuation_failed; }
1049 // It will free a region if it has allocated objects in it that are
1050 // all dead. It calls either free_region() or
1051 // free_humongous_region() depending on the type of the region that
1052 // is passed to it.
1053 void free_region_if_empty(HeapRegion* hr,
1054 size_t* pre_used,
1055 FreeRegionList* free_list,
1056 HumongousRegionSet* humongous_proxy_set,
1057 HRRSCleanupTask* hrrs_cleanup_task,
1058 bool par);
1060 // It appends the free list to the master free list and updates the
1061 // master humongous list according to the contents of the proxy
1062 // list. It also adjusts the total used bytes according to pre_used
1063 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1064 void update_sets_after_freeing_regions(size_t pre_used,
1065 FreeRegionList* free_list,
1066 HumongousRegionSet* humongous_proxy_set,
1067 bool par);
1069 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1070 virtual bool is_in(const void* p) const;
1072 // Return "TRUE" iff the given object address is within the collection
1073 // set.
1074 inline bool obj_in_cs(oop obj);
1076 // Return "TRUE" iff the given object address is in the reserved
1077 // region of g1 (excluding the permanent generation).
1078 bool is_in_g1_reserved(const void* p) const {
1079 return _g1_reserved.contains(p);
1080 }
1082 // Returns a MemRegion that corresponds to the space that has been
1083 // reserved for the heap
1084 MemRegion g1_reserved() {
1085 return _g1_reserved;
1086 }
1088 // Returns a MemRegion that corresponds to the space that has been
1089 // committed in the heap
1090 MemRegion g1_committed() {
1091 return _g1_committed;
1092 }
1094 virtual bool is_in_closed_subset(const void* p) const;
1096 // This resets the card table to all zeros. It is used after
1097 // a collection pause which used the card table to claim cards.
1098 void cleanUpCardTable();
1100 // Iteration functions.
1102 // Iterate over all the ref-containing fields of all objects, calling
1103 // "cl.do_oop" on each.
1104 virtual void oop_iterate(OopClosure* cl) {
1105 oop_iterate(cl, true);
1106 }
1107 void oop_iterate(OopClosure* cl, bool do_perm);
1109 // Same as above, restricted to a memory region.
1110 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1111 oop_iterate(mr, cl, true);
1112 }
1113 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1115 // Iterate over all objects, calling "cl.do_object" on each.
1116 virtual void object_iterate(ObjectClosure* cl) {
1117 object_iterate(cl, true);
1118 }
1119 virtual void safe_object_iterate(ObjectClosure* cl) {
1120 object_iterate(cl, true);
1121 }
1122 void object_iterate(ObjectClosure* cl, bool do_perm);
1124 // Iterate over all objects allocated since the last collection, calling
1125 // "cl.do_object" on each. The heap must have been initialized properly
1126 // to support this function, or else this call will fail.
1127 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1129 // Iterate over all spaces in use in the heap, in ascending address order.
1130 virtual void space_iterate(SpaceClosure* cl);
1132 // Iterate over heap regions, in address order, terminating the
1133 // iteration early if the "doHeapRegion" method returns "true".
1134 void heap_region_iterate(HeapRegionClosure* blk) const;
1136 // Iterate over heap regions starting with r (or the first region if "r"
1137 // is NULL), in address order, terminating early if the "doHeapRegion"
1138 // method returns "true".
1139 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1141 // Return the region with the given index. It assumes the index is valid.
1142 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1144 // Divide the heap region sequence into "chunks" of some size (the number
1145 // of regions divided by the number of parallel threads times some
1146 // overpartition factor, currently 4). Assumes that this will be called
1147 // in parallel by ParallelGCThreads worker threads with discinct worker
1148 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1149 // calls will use the same "claim_value", and that that claim value is
1150 // different from the claim_value of any heap region before the start of
1151 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1152 // attempting to claim the first region in each chunk, and, if
1153 // successful, applying the closure to each region in the chunk (and
1154 // setting the claim value of the second and subsequent regions of the
1155 // chunk.) For now requires that "doHeapRegion" always returns "false",
1156 // i.e., that a closure never attempt to abort a traversal.
1157 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1158 int worker,
1159 jint claim_value);
1161 // It resets all the region claim values to the default.
1162 void reset_heap_region_claim_values();
1164 #ifdef ASSERT
1165 bool check_heap_region_claim_values(jint claim_value);
1166 #endif // ASSERT
1168 // Iterate over the regions (if any) in the current collection set.
1169 void collection_set_iterate(HeapRegionClosure* blk);
1171 // As above but starting from region r
1172 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1174 // Returns the first (lowest address) compactible space in the heap.
1175 virtual CompactibleSpace* first_compactible_space();
1177 // A CollectedHeap will contain some number of spaces. This finds the
1178 // space containing a given address, or else returns NULL.
1179 virtual Space* space_containing(const void* addr) const;
1181 // A G1CollectedHeap will contain some number of heap regions. This
1182 // finds the region containing a given address, or else returns NULL.
1183 template <class T>
1184 inline HeapRegion* heap_region_containing(const T addr) const;
1186 // Like the above, but requires "addr" to be in the heap (to avoid a
1187 // null-check), and unlike the above, may return an continuing humongous
1188 // region.
1189 template <class T>
1190 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1192 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1193 // each address in the (reserved) heap is a member of exactly
1194 // one block. The defining characteristic of a block is that it is
1195 // possible to find its size, and thus to progress forward to the next
1196 // block. (Blocks may be of different sizes.) Thus, blocks may
1197 // represent Java objects, or they might be free blocks in a
1198 // free-list-based heap (or subheap), as long as the two kinds are
1199 // distinguishable and the size of each is determinable.
1201 // Returns the address of the start of the "block" that contains the
1202 // address "addr". We say "blocks" instead of "object" since some heaps
1203 // may not pack objects densely; a chunk may either be an object or a
1204 // non-object.
1205 virtual HeapWord* block_start(const void* addr) const;
1207 // Requires "addr" to be the start of a chunk, and returns its size.
1208 // "addr + size" is required to be the start of a new chunk, or the end
1209 // of the active area of the heap.
1210 virtual size_t block_size(const HeapWord* addr) const;
1212 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1213 // the block is an object.
1214 virtual bool block_is_obj(const HeapWord* addr) const;
1216 // Does this heap support heap inspection? (+PrintClassHistogram)
1217 virtual bool supports_heap_inspection() const { return true; }
1219 // Section on thread-local allocation buffers (TLABs)
1220 // See CollectedHeap for semantics.
1222 virtual bool supports_tlab_allocation() const;
1223 virtual size_t tlab_capacity(Thread* thr) const;
1224 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1226 // Can a compiler initialize a new object without store barriers?
1227 // This permission only extends from the creation of a new object
1228 // via a TLAB up to the first subsequent safepoint. If such permission
1229 // is granted for this heap type, the compiler promises to call
1230 // defer_store_barrier() below on any slow path allocation of
1231 // a new object for which such initializing store barriers will
1232 // have been elided. G1, like CMS, allows this, but should be
1233 // ready to provide a compensating write barrier as necessary
1234 // if that storage came out of a non-young region. The efficiency
1235 // of this implementation depends crucially on being able to
1236 // answer very efficiently in constant time whether a piece of
1237 // storage in the heap comes from a young region or not.
1238 // See ReduceInitialCardMarks.
1239 virtual bool can_elide_tlab_store_barriers() const {
1240 // 6920090: Temporarily disabled, because of lingering
1241 // instabilities related to RICM with G1. In the
1242 // interim, the option ReduceInitialCardMarksForG1
1243 // below is left solely as a debugging device at least
1244 // until 6920109 fixes the instabilities.
1245 return ReduceInitialCardMarksForG1;
1246 }
1248 virtual bool card_mark_must_follow_store() const {
1249 return true;
1250 }
1252 bool is_in_young(const oop obj) {
1253 HeapRegion* hr = heap_region_containing(obj);
1254 return hr != NULL && hr->is_young();
1255 }
1257 #ifdef ASSERT
1258 virtual bool is_in_partial_collection(const void* p);
1259 #endif
1261 virtual bool is_scavengable(const void* addr);
1263 // We don't need barriers for initializing stores to objects
1264 // in the young gen: for the SATB pre-barrier, there is no
1265 // pre-value that needs to be remembered; for the remembered-set
1266 // update logging post-barrier, we don't maintain remembered set
1267 // information for young gen objects.
1268 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1269 // Re 6920090, 6920109 above.
1270 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1271 return is_in_young(new_obj);
1272 }
1274 // Can a compiler elide a store barrier when it writes
1275 // a permanent oop into the heap? Applies when the compiler
1276 // is storing x to the heap, where x->is_perm() is true.
1277 virtual bool can_elide_permanent_oop_store_barriers() const {
1278 // At least until perm gen collection is also G1-ified, at
1279 // which point this should return false.
1280 return true;
1281 }
1283 // Returns "true" iff the given word_size is "very large".
1284 static bool isHumongous(size_t word_size) {
1285 // Note this has to be strictly greater-than as the TLABs
1286 // are capped at the humongous thresold and we want to
1287 // ensure that we don't try to allocate a TLAB as
1288 // humongous and that we don't allocate a humongous
1289 // object in a TLAB.
1290 return word_size > _humongous_object_threshold_in_words;
1291 }
1293 // Update mod union table with the set of dirty cards.
1294 void updateModUnion();
1296 // Set the mod union bits corresponding to the given memRegion. Note
1297 // that this is always a safe operation, since it doesn't clear any
1298 // bits.
1299 void markModUnionRange(MemRegion mr);
1301 // Records the fact that a marking phase is no longer in progress.
1302 void set_marking_complete() {
1303 _mark_in_progress = false;
1304 }
1305 void set_marking_started() {
1306 _mark_in_progress = true;
1307 }
1308 bool mark_in_progress() {
1309 return _mark_in_progress;
1310 }
1312 // Print the maximum heap capacity.
1313 virtual size_t max_capacity() const;
1315 virtual jlong millis_since_last_gc();
1317 // Perform any cleanup actions necessary before allowing a verification.
1318 virtual void prepare_for_verify();
1320 // Perform verification.
1322 // vo == UsePrevMarking -> use "prev" marking information,
1323 // vo == UseNextMarking -> use "next" marking information
1324 // vo == UseMarkWord -> use the mark word in the object header
1325 //
1326 // NOTE: Only the "prev" marking information is guaranteed to be
1327 // consistent most of the time, so most calls to this should use
1328 // vo == UsePrevMarking.
1329 // Currently, there is only one case where this is called with
1330 // vo == UseNextMarking, which is to verify the "next" marking
1331 // information at the end of remark.
1332 // Currently there is only one place where this is called with
1333 // vo == UseMarkWord, which is to verify the marking during a
1334 // full GC.
1335 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1337 // Override; it uses the "prev" marking information
1338 virtual void verify(bool allow_dirty, bool silent);
1339 // Default behavior by calling print(tty);
1340 virtual void print() const;
1341 // This calls print_on(st, PrintHeapAtGCExtended).
1342 virtual void print_on(outputStream* st) const;
1343 // If extended is true, it will print out information for all
1344 // regions in the heap by calling print_on_extended(st).
1345 virtual void print_on(outputStream* st, bool extended) const;
1346 virtual void print_on_extended(outputStream* st) const;
1348 virtual void print_gc_threads_on(outputStream* st) const;
1349 virtual void gc_threads_do(ThreadClosure* tc) const;
1351 // Override
1352 void print_tracing_info() const;
1354 // The following two methods are helpful for debugging RSet issues.
1355 void print_cset_rsets() PRODUCT_RETURN;
1356 void print_all_rsets() PRODUCT_RETURN;
1358 // Convenience function to be used in situations where the heap type can be
1359 // asserted to be this type.
1360 static G1CollectedHeap* heap();
1362 void empty_young_list();
1364 void set_region_short_lived_locked(HeapRegion* hr);
1365 // add appropriate methods for any other surv rate groups
1367 YoungList* young_list() { return _young_list; }
1369 // debugging
1370 bool check_young_list_well_formed() {
1371 return _young_list->check_list_well_formed();
1372 }
1374 bool check_young_list_empty(bool check_heap,
1375 bool check_sample = true);
1377 // *** Stuff related to concurrent marking. It's not clear to me that so
1378 // many of these need to be public.
1380 // The functions below are helper functions that a subclass of
1381 // "CollectedHeap" can use in the implementation of its virtual
1382 // functions.
1383 // This performs a concurrent marking of the live objects in a
1384 // bitmap off to the side.
1385 void doConcurrentMark();
1387 bool isMarkedPrev(oop obj) const;
1388 bool isMarkedNext(oop obj) const;
1390 // vo == UsePrevMarking -> use "prev" marking information,
1391 // vo == UseNextMarking -> use "next" marking information,
1392 // vo == UseMarkWord -> use mark word from object header
1393 bool is_obj_dead_cond(const oop obj,
1394 const HeapRegion* hr,
1395 const VerifyOption vo) const {
1397 switch (vo) {
1398 case VerifyOption_G1UsePrevMarking:
1399 return is_obj_dead(obj, hr);
1400 case VerifyOption_G1UseNextMarking:
1401 return is_obj_ill(obj, hr);
1402 default:
1403 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1404 return !obj->is_gc_marked();
1405 }
1406 }
1408 // Determine if an object is dead, given the object and also
1409 // the region to which the object belongs. An object is dead
1410 // iff a) it was not allocated since the last mark and b) it
1411 // is not marked.
1413 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1414 return
1415 !hr->obj_allocated_since_prev_marking(obj) &&
1416 !isMarkedPrev(obj);
1417 }
1419 // This is used when copying an object to survivor space.
1420 // If the object is marked live, then we mark the copy live.
1421 // If the object is allocated since the start of this mark
1422 // cycle, then we mark the copy live.
1423 // If the object has been around since the previous mark
1424 // phase, and hasn't been marked yet during this phase,
1425 // then we don't mark it, we just wait for the
1426 // current marking cycle to get to it.
1428 // This function returns true when an object has been
1429 // around since the previous marking and hasn't yet
1430 // been marked during this marking.
1432 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1433 return
1434 !hr->obj_allocated_since_next_marking(obj) &&
1435 !isMarkedNext(obj);
1436 }
1438 // Determine if an object is dead, given only the object itself.
1439 // This will find the region to which the object belongs and
1440 // then call the region version of the same function.
1442 // Added if it is in permanent gen it isn't dead.
1443 // Added if it is NULL it isn't dead.
1445 // vo == UsePrevMarking -> use "prev" marking information,
1446 // vo == UseNextMarking -> use "next" marking information,
1447 // vo == UseMarkWord -> use mark word from object header
1448 bool is_obj_dead_cond(const oop obj,
1449 const VerifyOption vo) const {
1451 switch (vo) {
1452 case VerifyOption_G1UsePrevMarking:
1453 return is_obj_dead(obj);
1454 case VerifyOption_G1UseNextMarking:
1455 return is_obj_ill(obj);
1456 default:
1457 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1458 return !obj->is_gc_marked();
1459 }
1460 }
1462 bool is_obj_dead(const oop obj) const {
1463 const HeapRegion* hr = heap_region_containing(obj);
1464 if (hr == NULL) {
1465 if (Universe::heap()->is_in_permanent(obj))
1466 return false;
1467 else if (obj == NULL) return false;
1468 else return true;
1469 }
1470 else return is_obj_dead(obj, hr);
1471 }
1473 bool is_obj_ill(const oop obj) const {
1474 const HeapRegion* hr = heap_region_containing(obj);
1475 if (hr == NULL) {
1476 if (Universe::heap()->is_in_permanent(obj))
1477 return false;
1478 else if (obj == NULL) return false;
1479 else return true;
1480 }
1481 else return is_obj_ill(obj, hr);
1482 }
1484 // The following is just to alert the verification code
1485 // that a full collection has occurred and that the
1486 // remembered sets are no longer up to date.
1487 bool _full_collection;
1488 void set_full_collection() { _full_collection = true;}
1489 void clear_full_collection() {_full_collection = false;}
1490 bool full_collection() {return _full_collection;}
1492 ConcurrentMark* concurrent_mark() const { return _cm; }
1493 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1495 // The dirty cards region list is used to record a subset of regions
1496 // whose cards need clearing. The list if populated during the
1497 // remembered set scanning and drained during the card table
1498 // cleanup. Although the methods are reentrant, population/draining
1499 // phases must not overlap. For synchronization purposes the last
1500 // element on the list points to itself.
1501 HeapRegion* _dirty_cards_region_list;
1502 void push_dirty_cards_region(HeapRegion* hr);
1503 HeapRegion* pop_dirty_cards_region();
1505 public:
1506 void stop_conc_gc_threads();
1508 // <NEW PREDICTION>
1510 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1511 void check_if_region_is_too_expensive(double predicted_time_ms);
1512 size_t pending_card_num();
1513 size_t max_pending_card_num();
1514 size_t cards_scanned();
1516 // </NEW PREDICTION>
1518 protected:
1519 size_t _max_heap_capacity;
1520 };
1522 #define use_local_bitmaps 1
1523 #define verify_local_bitmaps 0
1524 #define oop_buffer_length 256
1526 #ifndef PRODUCT
1527 class GCLabBitMap;
1528 class GCLabBitMapClosure: public BitMapClosure {
1529 private:
1530 ConcurrentMark* _cm;
1531 GCLabBitMap* _bitmap;
1533 public:
1534 GCLabBitMapClosure(ConcurrentMark* cm,
1535 GCLabBitMap* bitmap) {
1536 _cm = cm;
1537 _bitmap = bitmap;
1538 }
1540 virtual bool do_bit(size_t offset);
1541 };
1542 #endif // !PRODUCT
1544 class GCLabBitMap: public BitMap {
1545 private:
1546 ConcurrentMark* _cm;
1548 int _shifter;
1549 size_t _bitmap_word_covers_words;
1551 // beginning of the heap
1552 HeapWord* _heap_start;
1554 // this is the actual start of the GCLab
1555 HeapWord* _real_start_word;
1557 // this is the actual end of the GCLab
1558 HeapWord* _real_end_word;
1560 // this is the first word, possibly located before the actual start
1561 // of the GCLab, that corresponds to the first bit of the bitmap
1562 HeapWord* _start_word;
1564 // size of a GCLab in words
1565 size_t _gclab_word_size;
1567 static int shifter() {
1568 return MinObjAlignment - 1;
1569 }
1571 // how many heap words does a single bitmap word corresponds to?
1572 static size_t bitmap_word_covers_words() {
1573 return BitsPerWord << shifter();
1574 }
1576 size_t gclab_word_size() const {
1577 return _gclab_word_size;
1578 }
1580 // Calculates actual GCLab size in words
1581 size_t gclab_real_word_size() const {
1582 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1583 / BitsPerWord;
1584 }
1586 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1587 size_t bits_in_bitmap = gclab_word_size >> shifter();
1588 // We are going to ensure that the beginning of a word in this
1589 // bitmap also corresponds to the beginning of a word in the
1590 // global marking bitmap. To handle the case where a GCLab
1591 // starts from the middle of the bitmap, we need to add enough
1592 // space (i.e. up to a bitmap word) to ensure that we have
1593 // enough bits in the bitmap.
1594 return bits_in_bitmap + BitsPerWord - 1;
1595 }
1596 public:
1597 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1598 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1599 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1600 _shifter(shifter()),
1601 _bitmap_word_covers_words(bitmap_word_covers_words()),
1602 _heap_start(heap_start),
1603 _gclab_word_size(gclab_word_size),
1604 _real_start_word(NULL),
1605 _real_end_word(NULL),
1606 _start_word(NULL)
1607 {
1608 guarantee( size_in_words() >= bitmap_size_in_words(),
1609 "just making sure");
1610 }
1612 inline unsigned heapWordToOffset(HeapWord* addr) {
1613 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1614 assert(offset < size(), "offset should be within bounds");
1615 return offset;
1616 }
1618 inline HeapWord* offsetToHeapWord(size_t offset) {
1619 HeapWord* addr = _start_word + (offset << _shifter);
1620 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1621 return addr;
1622 }
1624 bool fields_well_formed() {
1625 bool ret1 = (_real_start_word == NULL) &&
1626 (_real_end_word == NULL) &&
1627 (_start_word == NULL);
1628 if (ret1)
1629 return true;
1631 bool ret2 = _real_start_word >= _start_word &&
1632 _start_word < _real_end_word &&
1633 (_real_start_word + _gclab_word_size) == _real_end_word &&
1634 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1635 > _real_end_word;
1636 return ret2;
1637 }
1639 inline bool mark(HeapWord* addr) {
1640 guarantee(use_local_bitmaps, "invariant");
1641 assert(fields_well_formed(), "invariant");
1643 if (addr >= _real_start_word && addr < _real_end_word) {
1644 assert(!isMarked(addr), "should not have already been marked");
1646 // first mark it on the bitmap
1647 at_put(heapWordToOffset(addr), true);
1649 return true;
1650 } else {
1651 return false;
1652 }
1653 }
1655 inline bool isMarked(HeapWord* addr) {
1656 guarantee(use_local_bitmaps, "invariant");
1657 assert(fields_well_formed(), "invariant");
1659 return at(heapWordToOffset(addr));
1660 }
1662 void set_buffer(HeapWord* start) {
1663 guarantee(use_local_bitmaps, "invariant");
1664 clear();
1666 assert(start != NULL, "invariant");
1667 _real_start_word = start;
1668 _real_end_word = start + _gclab_word_size;
1670 size_t diff =
1671 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1672 _start_word = start - diff;
1674 assert(fields_well_formed(), "invariant");
1675 }
1677 #ifndef PRODUCT
1678 void verify() {
1679 // verify that the marks have been propagated
1680 GCLabBitMapClosure cl(_cm, this);
1681 iterate(&cl);
1682 }
1683 #endif // PRODUCT
1685 void retire() {
1686 guarantee(use_local_bitmaps, "invariant");
1687 assert(fields_well_formed(), "invariant");
1689 if (_start_word != NULL) {
1690 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1692 // this means that the bitmap was set up for the GCLab
1693 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1695 mark_bitmap->mostly_disjoint_range_union(this,
1696 0, // always start from the start of the bitmap
1697 _start_word,
1698 gclab_real_word_size());
1699 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1701 #ifndef PRODUCT
1702 if (use_local_bitmaps && verify_local_bitmaps)
1703 verify();
1704 #endif // PRODUCT
1705 } else {
1706 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1707 }
1708 }
1710 size_t bitmap_size_in_words() const {
1711 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1712 }
1714 };
1716 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1717 private:
1718 bool _retired;
1719 bool _should_mark_objects;
1720 GCLabBitMap _bitmap;
1722 public:
1723 G1ParGCAllocBuffer(size_t gclab_word_size);
1725 inline bool mark(HeapWord* addr) {
1726 guarantee(use_local_bitmaps, "invariant");
1727 assert(_should_mark_objects, "invariant");
1728 return _bitmap.mark(addr);
1729 }
1731 inline void set_buf(HeapWord* buf) {
1732 if (use_local_bitmaps && _should_mark_objects) {
1733 _bitmap.set_buffer(buf);
1734 }
1735 ParGCAllocBuffer::set_buf(buf);
1736 _retired = false;
1737 }
1739 inline void retire(bool end_of_gc, bool retain) {
1740 if (_retired)
1741 return;
1742 if (use_local_bitmaps && _should_mark_objects) {
1743 _bitmap.retire();
1744 }
1745 ParGCAllocBuffer::retire(end_of_gc, retain);
1746 _retired = true;
1747 }
1748 };
1750 class G1ParScanThreadState : public StackObj {
1751 protected:
1752 G1CollectedHeap* _g1h;
1753 RefToScanQueue* _refs;
1754 DirtyCardQueue _dcq;
1755 CardTableModRefBS* _ct_bs;
1756 G1RemSet* _g1_rem;
1758 G1ParGCAllocBuffer _surviving_alloc_buffer;
1759 G1ParGCAllocBuffer _tenured_alloc_buffer;
1760 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1761 ageTable _age_table;
1763 size_t _alloc_buffer_waste;
1764 size_t _undo_waste;
1766 OopsInHeapRegionClosure* _evac_failure_cl;
1767 G1ParScanHeapEvacClosure* _evac_cl;
1768 G1ParScanPartialArrayClosure* _partial_scan_cl;
1770 int _hash_seed;
1771 int _queue_num;
1773 size_t _term_attempts;
1775 double _start;
1776 double _start_strong_roots;
1777 double _strong_roots_time;
1778 double _start_term;
1779 double _term_time;
1781 // Map from young-age-index (0 == not young, 1 is youngest) to
1782 // surviving words. base is what we get back from the malloc call
1783 size_t* _surviving_young_words_base;
1784 // this points into the array, as we use the first few entries for padding
1785 size_t* _surviving_young_words;
1787 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1789 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1791 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1793 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1794 CardTableModRefBS* ctbs() { return _ct_bs; }
1796 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1797 if (!from->is_survivor()) {
1798 _g1_rem->par_write_ref(from, p, tid);
1799 }
1800 }
1802 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1803 // If the new value of the field points to the same region or
1804 // is the to-space, we don't need to include it in the Rset updates.
1805 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1806 size_t card_index = ctbs()->index_for(p);
1807 // If the card hasn't been added to the buffer, do it.
1808 if (ctbs()->mark_card_deferred(card_index)) {
1809 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1810 }
1811 }
1812 }
1814 public:
1815 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1817 ~G1ParScanThreadState() {
1818 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1819 }
1821 RefToScanQueue* refs() { return _refs; }
1822 ageTable* age_table() { return &_age_table; }
1824 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1825 return _alloc_buffers[purpose];
1826 }
1828 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1829 size_t undo_waste() const { return _undo_waste; }
1831 #ifdef ASSERT
1832 bool verify_ref(narrowOop* ref) const;
1833 bool verify_ref(oop* ref) const;
1834 bool verify_task(StarTask ref) const;
1835 #endif // ASSERT
1837 template <class T> void push_on_queue(T* ref) {
1838 assert(verify_ref(ref), "sanity");
1839 refs()->push(ref);
1840 }
1842 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1843 if (G1DeferredRSUpdate) {
1844 deferred_rs_update(from, p, tid);
1845 } else {
1846 immediate_rs_update(from, p, tid);
1847 }
1848 }
1850 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1852 HeapWord* obj = NULL;
1853 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1854 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1855 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1856 assert(gclab_word_size == alloc_buf->word_sz(),
1857 "dynamic resizing is not supported");
1858 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1859 alloc_buf->retire(false, false);
1861 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1862 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1863 // Otherwise.
1864 alloc_buf->set_buf(buf);
1866 obj = alloc_buf->allocate(word_sz);
1867 assert(obj != NULL, "buffer was definitely big enough...");
1868 } else {
1869 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1870 }
1871 return obj;
1872 }
1874 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1875 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1876 if (obj != NULL) return obj;
1877 return allocate_slow(purpose, word_sz);
1878 }
1880 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1881 if (alloc_buffer(purpose)->contains(obj)) {
1882 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1883 "should contain whole object");
1884 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1885 } else {
1886 CollectedHeap::fill_with_object(obj, word_sz);
1887 add_to_undo_waste(word_sz);
1888 }
1889 }
1891 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1892 _evac_failure_cl = evac_failure_cl;
1893 }
1894 OopsInHeapRegionClosure* evac_failure_closure() {
1895 return _evac_failure_cl;
1896 }
1898 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1899 _evac_cl = evac_cl;
1900 }
1902 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1903 _partial_scan_cl = partial_scan_cl;
1904 }
1906 int* hash_seed() { return &_hash_seed; }
1907 int queue_num() { return _queue_num; }
1909 size_t term_attempts() const { return _term_attempts; }
1910 void note_term_attempt() { _term_attempts++; }
1912 void start_strong_roots() {
1913 _start_strong_roots = os::elapsedTime();
1914 }
1915 void end_strong_roots() {
1916 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1917 }
1918 double strong_roots_time() const { return _strong_roots_time; }
1920 void start_term_time() {
1921 note_term_attempt();
1922 _start_term = os::elapsedTime();
1923 }
1924 void end_term_time() {
1925 _term_time += (os::elapsedTime() - _start_term);
1926 }
1927 double term_time() const { return _term_time; }
1929 double elapsed_time() const {
1930 return os::elapsedTime() - _start;
1931 }
1933 static void
1934 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1935 void
1936 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1938 size_t* surviving_young_words() {
1939 // We add on to hide entry 0 which accumulates surviving words for
1940 // age -1 regions (i.e. non-young ones)
1941 return _surviving_young_words;
1942 }
1944 void retire_alloc_buffers() {
1945 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1946 size_t waste = _alloc_buffers[ap]->words_remaining();
1947 add_to_alloc_buffer_waste(waste);
1948 _alloc_buffers[ap]->retire(true, false);
1949 }
1950 }
1952 template <class T> void deal_with_reference(T* ref_to_scan) {
1953 if (has_partial_array_mask(ref_to_scan)) {
1954 _partial_scan_cl->do_oop_nv(ref_to_scan);
1955 } else {
1956 // Note: we can use "raw" versions of "region_containing" because
1957 // "obj_to_scan" is definitely in the heap, and is not in a
1958 // humongous region.
1959 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
1960 _evac_cl->set_region(r);
1961 _evac_cl->do_oop_nv(ref_to_scan);
1962 }
1963 }
1965 void deal_with_reference(StarTask ref) {
1966 assert(verify_task(ref), "sanity");
1967 if (ref.is_narrow()) {
1968 deal_with_reference((narrowOop*)ref);
1969 } else {
1970 deal_with_reference((oop*)ref);
1971 }
1972 }
1974 public:
1975 void trim_queue();
1976 };
1978 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP