Wed, 12 Jan 2011 16:34:25 -0500
6994297: G1: do first-level slow-path allocations with a CAS
Summary: First attempt to allocate out the current alloc region using a CAS instead of taking the Heap_lock (first level of G1's slow allocation path). Only if that fails and it's necessary to replace the current alloc region take the Heap_lock (that's the second level of G1's slow allocation path).
Reviewed-by: johnc, brutisso, ysr
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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/g1RemSet.hpp"
30 #include "gc_implementation/g1/heapRegion.hpp"
31 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
32 #include "memory/barrierSet.hpp"
33 #include "memory/memRegion.hpp"
34 #include "memory/sharedHeap.hpp"
36 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
37 // It uses the "Garbage First" heap organization and algorithm, which
38 // may combine concurrent marking with parallel, incremental compaction of
39 // heap subsets that will yield large amounts of garbage.
41 class HeapRegion;
42 class HeapRegionSeq;
43 class PermanentGenerationSpec;
44 class GenerationSpec;
45 class OopsInHeapRegionClosure;
46 class G1ScanHeapEvacClosure;
47 class ObjectClosure;
48 class SpaceClosure;
49 class CompactibleSpaceClosure;
50 class Space;
51 class G1CollectorPolicy;
52 class GenRemSet;
53 class G1RemSet;
54 class HeapRegionRemSetIterator;
55 class ConcurrentMark;
56 class ConcurrentMarkThread;
57 class ConcurrentG1Refine;
58 class ConcurrentZFThread;
60 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
61 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
63 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
64 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
66 enum G1GCThreadGroups {
67 G1CRGroup = 0,
68 G1ZFGroup = 1,
69 G1CMGroup = 2,
70 G1CLGroup = 3
71 };
73 enum GCAllocPurpose {
74 GCAllocForTenured,
75 GCAllocForSurvived,
76 GCAllocPurposeCount
77 };
79 class YoungList : public CHeapObj {
80 private:
81 G1CollectedHeap* _g1h;
83 HeapRegion* _head;
85 HeapRegion* _survivor_head;
86 HeapRegion* _survivor_tail;
88 HeapRegion* _curr;
90 size_t _length;
91 size_t _survivor_length;
93 size_t _last_sampled_rs_lengths;
94 size_t _sampled_rs_lengths;
96 void empty_list(HeapRegion* list);
98 public:
99 YoungList(G1CollectedHeap* g1h);
101 void push_region(HeapRegion* hr);
102 void add_survivor_region(HeapRegion* hr);
104 void empty_list();
105 bool is_empty() { return _length == 0; }
106 size_t length() { return _length; }
107 size_t survivor_length() { return _survivor_length; }
109 void rs_length_sampling_init();
110 bool rs_length_sampling_more();
111 void rs_length_sampling_next();
113 void reset_sampled_info() {
114 _last_sampled_rs_lengths = 0;
115 }
116 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
118 // for development purposes
119 void reset_auxilary_lists();
120 void clear() { _head = NULL; _length = 0; }
122 void clear_survivors() {
123 _survivor_head = NULL;
124 _survivor_tail = NULL;
125 _survivor_length = 0;
126 }
128 HeapRegion* first_region() { return _head; }
129 HeapRegion* first_survivor_region() { return _survivor_head; }
130 HeapRegion* last_survivor_region() { return _survivor_tail; }
132 // debugging
133 bool check_list_well_formed();
134 bool check_list_empty(bool check_sample = true);
135 void print();
136 };
138 class RefineCardTableEntryClosure;
139 class G1CollectedHeap : public SharedHeap {
140 friend class VM_G1CollectForAllocation;
141 friend class VM_GenCollectForPermanentAllocation;
142 friend class VM_G1CollectFull;
143 friend class VM_G1IncCollectionPause;
144 friend class VMStructs;
146 // Closures used in implementation.
147 friend class G1ParCopyHelper;
148 friend class G1IsAliveClosure;
149 friend class G1EvacuateFollowersClosure;
150 friend class G1ParScanThreadState;
151 friend class G1ParScanClosureSuper;
152 friend class G1ParEvacuateFollowersClosure;
153 friend class G1ParTask;
154 friend class G1FreeGarbageRegionClosure;
155 friend class RefineCardTableEntryClosure;
156 friend class G1PrepareCompactClosure;
157 friend class RegionSorter;
158 friend class CountRCClosure;
159 friend class EvacPopObjClosure;
160 friend class G1ParCleanupCTTask;
162 // Other related classes.
163 friend class G1MarkSweep;
165 private:
166 // The one and only G1CollectedHeap, so static functions can find it.
167 static G1CollectedHeap* _g1h;
169 static size_t _humongous_object_threshold_in_words;
171 // Storage for the G1 heap (excludes the permanent generation).
172 VirtualSpace _g1_storage;
173 MemRegion _g1_reserved;
175 // The part of _g1_storage that is currently committed.
176 MemRegion _g1_committed;
178 // The maximum part of _g1_storage that has ever been committed.
179 MemRegion _g1_max_committed;
181 // The number of regions that are completely free.
182 size_t _free_regions;
184 // The number of regions we could create by expansion.
185 size_t _expansion_regions;
187 // Return the number of free regions in the heap (by direct counting.)
188 size_t count_free_regions();
189 // Return the number of free regions on the free and unclean lists.
190 size_t count_free_regions_list();
192 // The block offset table for the G1 heap.
193 G1BlockOffsetSharedArray* _bot_shared;
195 // Move all of the regions off the free lists, then rebuild those free
196 // lists, before and after full GC.
197 void tear_down_region_lists();
198 void rebuild_region_lists();
199 // This sets all non-empty regions to need zero-fill (which they will if
200 // they are empty after full collection.)
201 void set_used_regions_to_need_zero_fill();
203 // The sequence of all heap regions in the heap.
204 HeapRegionSeq* _hrs;
206 // The region from which normal-sized objects are currently being
207 // allocated. May be NULL.
208 HeapRegion* _cur_alloc_region;
210 // Postcondition: cur_alloc_region == NULL.
211 void abandon_cur_alloc_region();
212 void abandon_gc_alloc_regions();
214 // The to-space memory regions into which objects are being copied during
215 // a GC.
216 HeapRegion* _gc_alloc_regions[GCAllocPurposeCount];
217 size_t _gc_alloc_region_counts[GCAllocPurposeCount];
218 // These are the regions, one per GCAllocPurpose, that are half-full
219 // at the end of a collection and that we want to reuse during the
220 // next collection.
221 HeapRegion* _retained_gc_alloc_regions[GCAllocPurposeCount];
222 // This specifies whether we will keep the last half-full region at
223 // the end of a collection so that it can be reused during the next
224 // collection (this is specified per GCAllocPurpose)
225 bool _retain_gc_alloc_region[GCAllocPurposeCount];
227 // A list of the regions that have been set to be alloc regions in the
228 // current collection.
229 HeapRegion* _gc_alloc_region_list;
231 // Determines PLAB size for a particular allocation purpose.
232 static size_t desired_plab_sz(GCAllocPurpose purpose);
234 // When called by par thread, require par_alloc_during_gc_lock() to be held.
235 void push_gc_alloc_region(HeapRegion* hr);
237 // This should only be called single-threaded. Undeclares all GC alloc
238 // regions.
239 void forget_alloc_region_list();
241 // Should be used to set an alloc region, because there's other
242 // associated bookkeeping.
243 void set_gc_alloc_region(int purpose, HeapRegion* r);
245 // Check well-formedness of alloc region list.
246 bool check_gc_alloc_regions();
248 // Outside of GC pauses, the number of bytes used in all regions other
249 // than the current allocation region.
250 size_t _summary_bytes_used;
252 // This is used for a quick test on whether a reference points into
253 // the collection set or not. Basically, we have an array, with one
254 // byte per region, and that byte denotes whether the corresponding
255 // region is in the collection set or not. The entry corresponding
256 // the bottom of the heap, i.e., region 0, is pointed to by
257 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
258 // biased so that it actually points to address 0 of the address
259 // space, to make the test as fast as possible (we can simply shift
260 // the address to address into it, instead of having to subtract the
261 // bottom of the heap from the address before shifting it; basically
262 // it works in the same way the card table works).
263 bool* _in_cset_fast_test;
265 // The allocated array used for the fast test on whether a reference
266 // points into the collection set or not. This field is also used to
267 // free the array.
268 bool* _in_cset_fast_test_base;
270 // The length of the _in_cset_fast_test_base array.
271 size_t _in_cset_fast_test_length;
273 volatile unsigned _gc_time_stamp;
275 size_t* _surviving_young_words;
277 void setup_surviving_young_words();
278 void update_surviving_young_words(size_t* surv_young_words);
279 void cleanup_surviving_young_words();
281 // It decides whether an explicit GC should start a concurrent cycle
282 // instead of doing a STW GC. Currently, a concurrent cycle is
283 // explicitly started if:
284 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
285 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
286 bool should_do_concurrent_full_gc(GCCause::Cause cause);
288 // Keeps track of how many "full collections" (i.e., Full GCs or
289 // concurrent cycles) we have completed. The number of them we have
290 // started is maintained in _total_full_collections in CollectedHeap.
291 volatile unsigned int _full_collections_completed;
293 // These are macros so that, if the assert fires, we get the correct
294 // line number, file, etc.
296 #define heap_locking_asserts_err_msg(__extra_message) \
297 err_msg("%s : Heap_lock %slocked, %sat a safepoint", \
298 (__extra_message), \
299 (!Heap_lock->owned_by_self()) ? "NOT " : "", \
300 (!SafepointSynchronize::is_at_safepoint()) ? "NOT " : "")
302 #define assert_heap_locked() \
303 do { \
304 assert(Heap_lock->owned_by_self(), \
305 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
306 } while (0)
308 #define assert_heap_locked_or_at_safepoint() \
309 do { \
310 assert(Heap_lock->owned_by_self() || \
311 SafepointSynchronize::is_at_safepoint(), \
312 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
313 "should be at a safepoint")); \
314 } while (0)
316 #define assert_heap_locked_and_not_at_safepoint() \
317 do { \
318 assert(Heap_lock->owned_by_self() && \
319 !SafepointSynchronize::is_at_safepoint(), \
320 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
321 "should not be at a safepoint")); \
322 } while (0)
324 #define assert_heap_not_locked() \
325 do { \
326 assert(!Heap_lock->owned_by_self(), \
327 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
328 } while (0)
330 #define assert_heap_not_locked_and_not_at_safepoint() \
331 do { \
332 assert(!Heap_lock->owned_by_self() && \
333 !SafepointSynchronize::is_at_safepoint(), \
334 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
335 "should not be at a safepoint")); \
336 } while (0)
338 #define assert_at_safepoint() \
339 do { \
340 assert(SafepointSynchronize::is_at_safepoint(), \
341 heap_locking_asserts_err_msg("should be at a safepoint")); \
342 } while (0)
344 #define assert_not_at_safepoint() \
345 do { \
346 assert(!SafepointSynchronize::is_at_safepoint(), \
347 heap_locking_asserts_err_msg("should not be at a safepoint")); \
348 } while (0)
350 protected:
352 // Returns "true" iff none of the gc alloc regions have any allocations
353 // since the last call to "save_marks".
354 bool all_alloc_regions_no_allocs_since_save_marks();
355 // Perform finalization stuff on all allocation regions.
356 void retire_all_alloc_regions();
358 // The number of regions allocated to hold humongous objects.
359 int _num_humongous_regions;
360 YoungList* _young_list;
362 // The current policy object for the collector.
363 G1CollectorPolicy* _g1_policy;
365 // Parallel allocation lock to protect the current allocation region.
366 Mutex _par_alloc_during_gc_lock;
367 Mutex* par_alloc_during_gc_lock() { return &_par_alloc_during_gc_lock; }
369 // If possible/desirable, allocate a new HeapRegion for normal object
370 // allocation sufficient for an allocation of the given "word_size".
371 // If "do_expand" is true, will attempt to expand the heap if necessary
372 // to to satisfy the request. If "zero_filled" is true, requires a
373 // zero-filled region.
374 // (Returning NULL will trigger a GC.)
375 virtual HeapRegion* newAllocRegion_work(size_t word_size,
376 bool do_expand,
377 bool zero_filled);
379 virtual HeapRegion* newAllocRegion(size_t word_size,
380 bool zero_filled = true) {
381 return newAllocRegion_work(word_size, false, zero_filled);
382 }
383 virtual HeapRegion* newAllocRegionWithExpansion(int purpose,
384 size_t word_size,
385 bool zero_filled = true);
387 // Attempt to allocate an object of the given (very large) "word_size".
388 // Returns "NULL" on failure.
389 virtual HeapWord* humongous_obj_allocate(size_t word_size);
391 // The following two methods, allocate_new_tlab() and
392 // mem_allocate(), are the two main entry points from the runtime
393 // into the G1's allocation routines. They have the following
394 // assumptions:
395 //
396 // * They should both be called outside safepoints.
397 //
398 // * They should both be called without holding the Heap_lock.
399 //
400 // * All allocation requests for new TLABs should go to
401 // allocate_new_tlab().
402 //
403 // * All non-TLAB allocation requests should go to mem_allocate()
404 // and mem_allocate() should never be called with is_tlab == true.
405 //
406 // * If the GC locker is active we currently stall until we can
407 // allocate a new young region. This will be changed in the
408 // near future (see CR 6994056).
409 //
410 // * If either call cannot satisfy the allocation request using the
411 // current allocating region, they will try to get a new one. If
412 // this fails, they will attempt to do an evacuation pause and
413 // retry the allocation.
414 //
415 // * If all allocation attempts fail, even after trying to schedule
416 // an evacuation pause, allocate_new_tlab() will return NULL,
417 // whereas mem_allocate() will attempt a heap expansion and/or
418 // schedule a Full GC.
419 //
420 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
421 // should never be called with word_size being humongous. All
422 // humongous allocation requests should go to mem_allocate() which
423 // will satisfy them with a special path.
425 virtual HeapWord* allocate_new_tlab(size_t word_size);
427 virtual HeapWord* mem_allocate(size_t word_size,
428 bool is_noref,
429 bool is_tlab, /* expected to be false */
430 bool* gc_overhead_limit_was_exceeded);
432 // The following methods, allocate_from_cur_allocation_region(),
433 // attempt_allocation(), attempt_allocation_locked(),
434 // replace_cur_alloc_region_and_allocate(),
435 // attempt_allocation_slow(), and attempt_allocation_humongous()
436 // have very awkward pre- and post-conditions with respect to
437 // locking:
438 //
439 // If they are called outside a safepoint they assume the caller
440 // holds the Heap_lock when it calls them. However, on exit they
441 // will release the Heap_lock if they return a non-NULL result, but
442 // keep holding the Heap_lock if they return a NULL result. The
443 // reason for this is that we need to dirty the cards that span
444 // allocated blocks on young regions to avoid having to take the
445 // slow path of the write barrier (for performance reasons we don't
446 // update RSets for references whose source is a young region, so we
447 // don't need to look at dirty cards on young regions). But, doing
448 // this card dirtying while holding the Heap_lock can be a
449 // scalability bottleneck, especially given that some allocation
450 // requests might be of non-trivial size (and the larger the region
451 // size is, the fewer allocations requests will be considered
452 // humongous, as the humongous size limit is a fraction of the
453 // region size). So, when one of these calls succeeds in allocating
454 // a block it does the card dirtying after it releases the Heap_lock
455 // which is why it will return without holding it.
456 //
457 // The above assymetry is the reason why locking / unlocking is done
458 // explicitly (i.e., with Heap_lock->lock() and
459 // Heap_lock->unlocked()) instead of using MutexLocker and
460 // MutexUnlocker objects. The latter would ensure that the lock is
461 // unlocked / re-locked at every possible exit out of the basic
462 // block. However, we only want that action to happen in selected
463 // places.
464 //
465 // Further, if the above methods are called during a safepoint, then
466 // naturally there's no assumption about the Heap_lock being held or
467 // there's no attempt to unlock it. The parameter at_safepoint
468 // indicates whether the call is made during a safepoint or not (as
469 // an optimization, to avoid reading the global flag with
470 // SafepointSynchronize::is_at_safepoint()).
471 //
472 // The methods share these parameters:
473 //
474 // * word_size : the size of the allocation request in words
475 // * at_safepoint : whether the call is done at a safepoint; this
476 // also determines whether a GC is permitted
477 // (at_safepoint == false) or not (at_safepoint == true)
478 // * do_dirtying : whether the method should dirty the allocated
479 // block before returning
480 //
481 // They all return either the address of the block, if they
482 // successfully manage to allocate it, or NULL.
484 // It tries to satisfy an allocation request out of the current
485 // alloc region, which is passed as a parameter. It assumes that the
486 // caller has checked that the current alloc region is not NULL.
487 // Given that the caller has to check the current alloc region for
488 // at least NULL, it might as well pass it as the first parameter so
489 // that the method doesn't have to read it from the
490 // _cur_alloc_region field again. It is called from both
491 // attempt_allocation() and attempt_allocation_locked() and the
492 // with_heap_lock parameter indicates whether the caller was holding
493 // the heap lock when it called it or not.
494 inline HeapWord* allocate_from_cur_alloc_region(HeapRegion* cur_alloc_region,
495 size_t word_size,
496 bool with_heap_lock);
498 // First-level of allocation slow path: it attempts to allocate out
499 // of the current alloc region in a lock-free manner using a CAS. If
500 // that fails it takes the Heap_lock and calls
501 // attempt_allocation_locked() for the second-level slow path.
502 inline HeapWord* attempt_allocation(size_t word_size);
504 // Second-level of allocation slow path: while holding the Heap_lock
505 // it tries to allocate out of the current alloc region and, if that
506 // fails, tries to allocate out of a new current alloc region.
507 inline HeapWord* attempt_allocation_locked(size_t word_size);
509 // It assumes that the current alloc region has been retired and
510 // tries to allocate a new one. If it's successful, it performs the
511 // allocation out of the new current alloc region and updates
512 // _cur_alloc_region. Normally, it would try to allocate a new
513 // region if the young gen is not full, unless can_expand is true in
514 // which case it would always try to allocate a new region.
515 HeapWord* replace_cur_alloc_region_and_allocate(size_t word_size,
516 bool at_safepoint,
517 bool do_dirtying,
518 bool can_expand);
520 // Third-level of allocation slow path: when we are unable to
521 // allocate a new current alloc region to satisfy an allocation
522 // request (i.e., when attempt_allocation_locked() fails). It will
523 // try to do an evacuation pause, which might stall due to the GC
524 // locker, and retry the allocation attempt when appropriate.
525 HeapWord* attempt_allocation_slow(size_t word_size);
527 // The method that tries to satisfy a humongous allocation
528 // request. If it cannot satisfy it it will try to do an evacuation
529 // pause to perhaps reclaim enough space to be able to satisfy the
530 // allocation request afterwards.
531 HeapWord* attempt_allocation_humongous(size_t word_size,
532 bool at_safepoint);
534 // It does the common work when we are retiring the current alloc region.
535 inline void retire_cur_alloc_region_common(HeapRegion* cur_alloc_region);
537 // It retires the current alloc region, which is passed as a
538 // parameter (since, typically, the caller is already holding on to
539 // it). It sets _cur_alloc_region to NULL.
540 void retire_cur_alloc_region(HeapRegion* cur_alloc_region);
542 // It attempts to do an allocation immediately before or after an
543 // evacuation pause and can only be called by the VM thread. It has
544 // slightly different assumptions that the ones before (i.e.,
545 // assumes that the current alloc region has been retired).
546 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
547 bool expect_null_cur_alloc_region);
549 // It dirties the cards that cover the block so that so that the post
550 // write barrier never queues anything when updating objects on this
551 // block. It is assumed (and in fact we assert) that the block
552 // belongs to a young region.
553 inline void dirty_young_block(HeapWord* start, size_t word_size);
555 // Allocate blocks during garbage collection. Will ensure an
556 // allocation region, either by picking one or expanding the
557 // heap, and then allocate a block of the given size. The block
558 // may not be a humongous - it must fit into a single heap region.
559 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
561 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
562 HeapRegion* alloc_region,
563 bool par,
564 size_t word_size);
566 // Ensure that no further allocations can happen in "r", bearing in mind
567 // that parallel threads might be attempting allocations.
568 void par_allocate_remaining_space(HeapRegion* r);
570 // Retires an allocation region when it is full or at the end of a
571 // GC pause.
572 void retire_alloc_region(HeapRegion* alloc_region, bool par);
574 // - if explicit_gc is true, the GC is for a System.gc() or a heap
575 // inspection request and should collect the entire heap
576 // - if clear_all_soft_refs is true, all soft references should be
577 // cleared during the GC
578 // - if explicit_gc is false, word_size describes the allocation that
579 // the GC should attempt (at least) to satisfy
580 // - it returns false if it is unable to do the collection due to the
581 // GC locker being active, true otherwise
582 bool do_collection(bool explicit_gc,
583 bool clear_all_soft_refs,
584 size_t word_size);
586 // Callback from VM_G1CollectFull operation.
587 // Perform a full collection.
588 void do_full_collection(bool clear_all_soft_refs);
590 // Resize the heap if necessary after a full collection. If this is
591 // after a collect-for allocation, "word_size" is the allocation size,
592 // and will be considered part of the used portion of the heap.
593 void resize_if_necessary_after_full_collection(size_t word_size);
595 // Callback from VM_G1CollectForAllocation operation.
596 // This function does everything necessary/possible to satisfy a
597 // failed allocation request (including collection, expansion, etc.)
598 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
600 // Attempting to expand the heap sufficiently
601 // to support an allocation of the given "word_size". If
602 // successful, perform the allocation and return the address of the
603 // allocated block, or else "NULL".
604 HeapWord* expand_and_allocate(size_t word_size);
606 public:
607 // Expand the garbage-first heap by at least the given size (in bytes!).
608 // (Rounds up to a HeapRegion boundary.)
609 virtual void expand(size_t expand_bytes);
611 // Do anything common to GC's.
612 virtual void gc_prologue(bool full);
613 virtual void gc_epilogue(bool full);
615 // We register a region with the fast "in collection set" test. We
616 // simply set to true the array slot corresponding to this region.
617 void register_region_with_in_cset_fast_test(HeapRegion* r) {
618 assert(_in_cset_fast_test_base != NULL, "sanity");
619 assert(r->in_collection_set(), "invariant");
620 int index = r->hrs_index();
621 assert(0 <= index && (size_t) index < _in_cset_fast_test_length, "invariant");
622 assert(!_in_cset_fast_test_base[index], "invariant");
623 _in_cset_fast_test_base[index] = true;
624 }
626 // This is a fast test on whether a reference points into the
627 // collection set or not. It does not assume that the reference
628 // points into the heap; if it doesn't, it will return false.
629 bool in_cset_fast_test(oop obj) {
630 assert(_in_cset_fast_test != NULL, "sanity");
631 if (_g1_committed.contains((HeapWord*) obj)) {
632 // no need to subtract the bottom of the heap from obj,
633 // _in_cset_fast_test is biased
634 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
635 bool ret = _in_cset_fast_test[index];
636 // let's make sure the result is consistent with what the slower
637 // test returns
638 assert( ret || !obj_in_cs(obj), "sanity");
639 assert(!ret || obj_in_cs(obj), "sanity");
640 return ret;
641 } else {
642 return false;
643 }
644 }
646 void clear_cset_fast_test() {
647 assert(_in_cset_fast_test_base != NULL, "sanity");
648 memset(_in_cset_fast_test_base, false,
649 _in_cset_fast_test_length * sizeof(bool));
650 }
652 // This is called at the end of either a concurrent cycle or a Full
653 // GC to update the number of full collections completed. Those two
654 // can happen in a nested fashion, i.e., we start a concurrent
655 // cycle, a Full GC happens half-way through it which ends first,
656 // and then the cycle notices that a Full GC happened and ends
657 // too. The concurrent parameter is a boolean to help us do a bit
658 // tighter consistency checking in the method. If concurrent is
659 // false, the caller is the inner caller in the nesting (i.e., the
660 // Full GC). If concurrent is true, the caller is the outer caller
661 // in this nesting (i.e., the concurrent cycle). Further nesting is
662 // not currently supported. The end of the this call also notifies
663 // the FullGCCount_lock in case a Java thread is waiting for a full
664 // GC to happen (e.g., it called System.gc() with
665 // +ExplicitGCInvokesConcurrent).
666 void increment_full_collections_completed(bool concurrent);
668 unsigned int full_collections_completed() {
669 return _full_collections_completed;
670 }
672 protected:
674 // Shrink the garbage-first heap by at most the given size (in bytes!).
675 // (Rounds down to a HeapRegion boundary.)
676 virtual void shrink(size_t expand_bytes);
677 void shrink_helper(size_t expand_bytes);
679 #if TASKQUEUE_STATS
680 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
681 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
682 void reset_taskqueue_stats();
683 #endif // TASKQUEUE_STATS
685 // Schedule the VM operation that will do an evacuation pause to
686 // satisfy an allocation request of word_size. *succeeded will
687 // return whether the VM operation was successful (it did do an
688 // evacuation pause) or not (another thread beat us to it or the GC
689 // locker was active). Given that we should not be holding the
690 // Heap_lock when we enter this method, we will pass the
691 // gc_count_before (i.e., total_collections()) as a parameter since
692 // it has to be read while holding the Heap_lock. Currently, both
693 // methods that call do_collection_pause() release the Heap_lock
694 // before the call, so it's easy to read gc_count_before just before.
695 HeapWord* do_collection_pause(size_t word_size,
696 unsigned int gc_count_before,
697 bool* succeeded);
699 // The guts of the incremental collection pause, executed by the vm
700 // thread. It returns false if it is unable to do the collection due
701 // to the GC locker being active, true otherwise
702 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
704 // Actually do the work of evacuating the collection set.
705 void evacuate_collection_set();
707 // The g1 remembered set of the heap.
708 G1RemSet* _g1_rem_set;
709 // And it's mod ref barrier set, used to track updates for the above.
710 ModRefBarrierSet* _mr_bs;
712 // A set of cards that cover the objects for which the Rsets should be updated
713 // concurrently after the collection.
714 DirtyCardQueueSet _dirty_card_queue_set;
716 // The Heap Region Rem Set Iterator.
717 HeapRegionRemSetIterator** _rem_set_iterator;
719 // The closure used to refine a single card.
720 RefineCardTableEntryClosure* _refine_cte_cl;
722 // A function to check the consistency of dirty card logs.
723 void check_ct_logs_at_safepoint();
725 // A DirtyCardQueueSet that is used to hold cards that contain
726 // references into the current collection set. This is used to
727 // update the remembered sets of the regions in the collection
728 // set in the event of an evacuation failure.
729 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
731 // After a collection pause, make the regions in the CS into free
732 // regions.
733 void free_collection_set(HeapRegion* cs_head);
735 // Abandon the current collection set without recording policy
736 // statistics or updating free lists.
737 void abandon_collection_set(HeapRegion* cs_head);
739 // Applies "scan_non_heap_roots" to roots outside the heap,
740 // "scan_rs" to roots inside the heap (having done "set_region" to
741 // indicate the region in which the root resides), and does "scan_perm"
742 // (setting the generation to the perm generation.) If "scan_rs" is
743 // NULL, then this step is skipped. The "worker_i"
744 // param is for use with parallel roots processing, and should be
745 // the "i" of the calling parallel worker thread's work(i) function.
746 // In the sequential case this param will be ignored.
747 void g1_process_strong_roots(bool collecting_perm_gen,
748 SharedHeap::ScanningOption so,
749 OopClosure* scan_non_heap_roots,
750 OopsInHeapRegionClosure* scan_rs,
751 OopsInGenClosure* scan_perm,
752 int worker_i);
754 // Apply "blk" to all the weak roots of the system. These include
755 // JNI weak roots, the code cache, system dictionary, symbol table,
756 // string table, and referents of reachable weak refs.
757 void g1_process_weak_roots(OopClosure* root_closure,
758 OopClosure* non_root_closure);
760 // Invoke "save_marks" on all heap regions.
761 void save_marks();
763 // Free a heap region.
764 void free_region(HeapRegion* hr);
765 // A component of "free_region", exposed for 'batching'.
766 // All the params after "hr" are out params: the used bytes of the freed
767 // region(s), the number of H regions cleared, the number of regions
768 // freed, and pointers to the head and tail of a list of freed contig
769 // regions, linked throught the "next_on_unclean_list" field.
770 void free_region_work(HeapRegion* hr,
771 size_t& pre_used,
772 size_t& cleared_h,
773 size_t& freed_regions,
774 UncleanRegionList* list,
775 bool par = false);
778 // The concurrent marker (and the thread it runs in.)
779 ConcurrentMark* _cm;
780 ConcurrentMarkThread* _cmThread;
781 bool _mark_in_progress;
783 // The concurrent refiner.
784 ConcurrentG1Refine* _cg1r;
786 // The concurrent zero-fill thread.
787 ConcurrentZFThread* _czft;
789 // The parallel task queues
790 RefToScanQueueSet *_task_queues;
792 // True iff a evacuation has failed in the current collection.
793 bool _evacuation_failed;
795 // Set the attribute indicating whether evacuation has failed in the
796 // current collection.
797 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
799 // Failed evacuations cause some logical from-space objects to have
800 // forwarding pointers to themselves. Reset them.
801 void remove_self_forwarding_pointers();
803 // When one is non-null, so is the other. Together, they each pair is
804 // an object with a preserved mark, and its mark value.
805 GrowableArray<oop>* _objs_with_preserved_marks;
806 GrowableArray<markOop>* _preserved_marks_of_objs;
808 // Preserve the mark of "obj", if necessary, in preparation for its mark
809 // word being overwritten with a self-forwarding-pointer.
810 void preserve_mark_if_necessary(oop obj, markOop m);
812 // The stack of evac-failure objects left to be scanned.
813 GrowableArray<oop>* _evac_failure_scan_stack;
814 // The closure to apply to evac-failure objects.
816 OopsInHeapRegionClosure* _evac_failure_closure;
817 // Set the field above.
818 void
819 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
820 _evac_failure_closure = evac_failure_closure;
821 }
823 // Push "obj" on the scan stack.
824 void push_on_evac_failure_scan_stack(oop obj);
825 // Process scan stack entries until the stack is empty.
826 void drain_evac_failure_scan_stack();
827 // True iff an invocation of "drain_scan_stack" is in progress; to
828 // prevent unnecessary recursion.
829 bool _drain_in_progress;
831 // Do any necessary initialization for evacuation-failure handling.
832 // "cl" is the closure that will be used to process evac-failure
833 // objects.
834 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
835 // Do any necessary cleanup for evacuation-failure handling data
836 // structures.
837 void finalize_for_evac_failure();
839 // An attempt to evacuate "obj" has failed; take necessary steps.
840 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
841 void handle_evacuation_failure_common(oop obj, markOop m);
844 // Ensure that the relevant gc_alloc regions are set.
845 void get_gc_alloc_regions();
846 // We're done with GC alloc regions. We are going to tear down the
847 // gc alloc list and remove the gc alloc tag from all the regions on
848 // that list. However, we will also retain the last (i.e., the one
849 // that is half-full) GC alloc region, per GCAllocPurpose, for
850 // possible reuse during the next collection, provided
851 // _retain_gc_alloc_region[] indicates that it should be the
852 // case. Said regions are kept in the _retained_gc_alloc_regions[]
853 // array. If the parameter totally is set, we will not retain any
854 // regions, irrespective of what _retain_gc_alloc_region[]
855 // indicates.
856 void release_gc_alloc_regions(bool totally);
857 #ifndef PRODUCT
858 // Useful for debugging.
859 void print_gc_alloc_regions();
860 #endif // !PRODUCT
862 // Instance of the concurrent mark is_alive closure for embedding
863 // into the reference processor as the is_alive_non_header. This
864 // prevents unnecessary additions to the discovered lists during
865 // concurrent discovery.
866 G1CMIsAliveClosure _is_alive_closure;
868 // ("Weak") Reference processing support
869 ReferenceProcessor* _ref_processor;
871 enum G1H_process_strong_roots_tasks {
872 G1H_PS_mark_stack_oops_do,
873 G1H_PS_refProcessor_oops_do,
874 // Leave this one last.
875 G1H_PS_NumElements
876 };
878 SubTasksDone* _process_strong_tasks;
880 // List of regions which require zero filling.
881 UncleanRegionList _unclean_region_list;
882 bool _unclean_regions_coming;
884 public:
886 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
888 void set_refine_cte_cl_concurrency(bool concurrent);
890 RefToScanQueue *task_queue(int i) const;
892 // A set of cards where updates happened during the GC
893 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
895 // A DirtyCardQueueSet that is used to hold cards that contain
896 // references into the current collection set. This is used to
897 // update the remembered sets of the regions in the collection
898 // set in the event of an evacuation failure.
899 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
900 { return _into_cset_dirty_card_queue_set; }
902 // Create a G1CollectedHeap with the specified policy.
903 // Must call the initialize method afterwards.
904 // May not return if something goes wrong.
905 G1CollectedHeap(G1CollectorPolicy* policy);
907 // Initialize the G1CollectedHeap to have the initial and
908 // maximum sizes, permanent generation, and remembered and barrier sets
909 // specified by the policy object.
910 jint initialize();
912 virtual void ref_processing_init();
914 void set_par_threads(int t) {
915 SharedHeap::set_par_threads(t);
916 _process_strong_tasks->set_n_threads(t);
917 }
919 virtual CollectedHeap::Name kind() const {
920 return CollectedHeap::G1CollectedHeap;
921 }
923 // The current policy object for the collector.
924 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
926 // Adaptive size policy. No such thing for g1.
927 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
929 // The rem set and barrier set.
930 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
931 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
933 // The rem set iterator.
934 HeapRegionRemSetIterator* rem_set_iterator(int i) {
935 return _rem_set_iterator[i];
936 }
938 HeapRegionRemSetIterator* rem_set_iterator() {
939 return _rem_set_iterator[0];
940 }
942 unsigned get_gc_time_stamp() {
943 return _gc_time_stamp;
944 }
946 void reset_gc_time_stamp() {
947 _gc_time_stamp = 0;
948 OrderAccess::fence();
949 }
951 void increment_gc_time_stamp() {
952 ++_gc_time_stamp;
953 OrderAccess::fence();
954 }
956 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
957 DirtyCardQueue* into_cset_dcq,
958 bool concurrent, int worker_i);
960 // The shared block offset table array.
961 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
963 // Reference Processing accessor
964 ReferenceProcessor* ref_processor() { return _ref_processor; }
966 // Reserved (g1 only; super method includes perm), capacity and the used
967 // portion in bytes.
968 size_t g1_reserved_obj_bytes() const { return _g1_reserved.byte_size(); }
969 virtual size_t capacity() const;
970 virtual size_t used() const;
971 // This should be called when we're not holding the heap lock. The
972 // result might be a bit inaccurate.
973 size_t used_unlocked() const;
974 size_t recalculate_used() const;
975 #ifndef PRODUCT
976 size_t recalculate_used_regions() const;
977 #endif // PRODUCT
979 // These virtual functions do the actual allocation.
980 // Some heaps may offer a contiguous region for shared non-blocking
981 // allocation, via inlined code (by exporting the address of the top and
982 // end fields defining the extent of the contiguous allocation region.)
983 // But G1CollectedHeap doesn't yet support this.
985 // Return an estimate of the maximum allocation that could be performed
986 // without triggering any collection or expansion activity. In a
987 // generational collector, for example, this is probably the largest
988 // allocation that could be supported (without expansion) in the youngest
989 // generation. It is "unsafe" because no locks are taken; the result
990 // should be treated as an approximation, not a guarantee, for use in
991 // heuristic resizing decisions.
992 virtual size_t unsafe_max_alloc();
994 virtual bool is_maximal_no_gc() const {
995 return _g1_storage.uncommitted_size() == 0;
996 }
998 // The total number of regions in the heap.
999 size_t n_regions();
1001 // The number of regions that are completely free.
1002 size_t max_regions();
1004 // The number of regions that are completely free.
1005 size_t free_regions();
1007 // The number of regions that are not completely free.
1008 size_t used_regions() { return n_regions() - free_regions(); }
1010 // True iff the ZF thread should run.
1011 bool should_zf();
1013 // The number of regions available for "regular" expansion.
1014 size_t expansion_regions() { return _expansion_regions; }
1016 #ifndef PRODUCT
1017 bool regions_accounted_for();
1018 bool print_region_accounting_info();
1019 void print_region_counts();
1020 #endif
1022 HeapRegion* alloc_region_from_unclean_list(bool zero_filled);
1023 HeapRegion* alloc_region_from_unclean_list_locked(bool zero_filled);
1025 void put_region_on_unclean_list(HeapRegion* r);
1026 void put_region_on_unclean_list_locked(HeapRegion* r);
1028 void prepend_region_list_on_unclean_list(UncleanRegionList* list);
1029 void prepend_region_list_on_unclean_list_locked(UncleanRegionList* list);
1031 void set_unclean_regions_coming(bool b);
1032 void set_unclean_regions_coming_locked(bool b);
1033 // Wait for cleanup to be complete.
1034 void wait_for_cleanup_complete();
1035 // Like above, but assumes that the calling thread owns the Heap_lock.
1036 void wait_for_cleanup_complete_locked();
1038 // Return the head of the unclean list.
1039 HeapRegion* peek_unclean_region_list_locked();
1040 // Remove and return the head of the unclean list.
1041 HeapRegion* pop_unclean_region_list_locked();
1043 // List of regions which are zero filled and ready for allocation.
1044 HeapRegion* _free_region_list;
1045 // Number of elements on the free list.
1046 size_t _free_region_list_size;
1048 // If the head of the unclean list is ZeroFilled, move it to the free
1049 // list.
1050 bool move_cleaned_region_to_free_list_locked();
1051 bool move_cleaned_region_to_free_list();
1053 void put_free_region_on_list_locked(HeapRegion* r);
1054 void put_free_region_on_list(HeapRegion* r);
1056 // Remove and return the head element of the free list.
1057 HeapRegion* pop_free_region_list_locked();
1059 // If "zero_filled" is true, we first try the free list, then we try the
1060 // unclean list, zero-filling the result. If "zero_filled" is false, we
1061 // first try the unclean list, then the zero-filled list.
1062 HeapRegion* alloc_free_region_from_lists(bool zero_filled);
1064 // Verify the integrity of the region lists.
1065 void remove_allocated_regions_from_lists();
1066 bool verify_region_lists();
1067 bool verify_region_lists_locked();
1068 size_t unclean_region_list_length();
1069 size_t free_region_list_length();
1071 // Perform a collection of the heap; intended for use in implementing
1072 // "System.gc". This probably implies as full a collection as the
1073 // "CollectedHeap" supports.
1074 virtual void collect(GCCause::Cause cause);
1076 // The same as above but assume that the caller holds the Heap_lock.
1077 void collect_locked(GCCause::Cause cause);
1079 // This interface assumes that it's being called by the
1080 // vm thread. It collects the heap assuming that the
1081 // heap lock is already held and that we are executing in
1082 // the context of the vm thread.
1083 virtual void collect_as_vm_thread(GCCause::Cause cause);
1085 // True iff a evacuation has failed in the most-recent collection.
1086 bool evacuation_failed() { return _evacuation_failed; }
1088 // Free a region if it is totally full of garbage. Returns the number of
1089 // bytes freed (0 ==> didn't free it).
1090 size_t free_region_if_totally_empty(HeapRegion *hr);
1091 void free_region_if_totally_empty_work(HeapRegion *hr,
1092 size_t& pre_used,
1093 size_t& cleared_h_regions,
1094 size_t& freed_regions,
1095 UncleanRegionList* list,
1096 bool par = false);
1098 // If we've done free region work that yields the given changes, update
1099 // the relevant global variables.
1100 void finish_free_region_work(size_t pre_used,
1101 size_t cleared_h_regions,
1102 size_t freed_regions,
1103 UncleanRegionList* list);
1106 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1107 virtual bool is_in(const void* p) const;
1109 // Return "TRUE" iff the given object address is within the collection
1110 // set.
1111 inline bool obj_in_cs(oop obj);
1113 // Return "TRUE" iff the given object address is in the reserved
1114 // region of g1 (excluding the permanent generation).
1115 bool is_in_g1_reserved(const void* p) const {
1116 return _g1_reserved.contains(p);
1117 }
1119 // Returns a MemRegion that corresponds to the space that has been
1120 // committed in the heap
1121 MemRegion g1_committed() {
1122 return _g1_committed;
1123 }
1125 NOT_PRODUCT(bool is_in_closed_subset(const void* p) const;)
1127 // Dirty card table entries covering a list of young regions.
1128 void dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list);
1130 // This resets the card table to all zeros. It is used after
1131 // a collection pause which used the card table to claim cards.
1132 void cleanUpCardTable();
1134 // Iteration functions.
1136 // Iterate over all the ref-containing fields of all objects, calling
1137 // "cl.do_oop" on each.
1138 virtual void oop_iterate(OopClosure* cl) {
1139 oop_iterate(cl, true);
1140 }
1141 void oop_iterate(OopClosure* cl, bool do_perm);
1143 // Same as above, restricted to a memory region.
1144 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1145 oop_iterate(mr, cl, true);
1146 }
1147 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1149 // Iterate over all objects, calling "cl.do_object" on each.
1150 virtual void object_iterate(ObjectClosure* cl) {
1151 object_iterate(cl, true);
1152 }
1153 virtual void safe_object_iterate(ObjectClosure* cl) {
1154 object_iterate(cl, true);
1155 }
1156 void object_iterate(ObjectClosure* cl, bool do_perm);
1158 // Iterate over all objects allocated since the last collection, calling
1159 // "cl.do_object" on each. The heap must have been initialized properly
1160 // to support this function, or else this call will fail.
1161 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1163 // Iterate over all spaces in use in the heap, in ascending address order.
1164 virtual void space_iterate(SpaceClosure* cl);
1166 // Iterate over heap regions, in address order, terminating the
1167 // iteration early if the "doHeapRegion" method returns "true".
1168 void heap_region_iterate(HeapRegionClosure* blk);
1170 // Iterate over heap regions starting with r (or the first region if "r"
1171 // is NULL), in address order, terminating early if the "doHeapRegion"
1172 // method returns "true".
1173 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk);
1175 // As above but starting from the region at index idx.
1176 void heap_region_iterate_from(int idx, HeapRegionClosure* blk);
1178 HeapRegion* region_at(size_t idx);
1180 // Divide the heap region sequence into "chunks" of some size (the number
1181 // of regions divided by the number of parallel threads times some
1182 // overpartition factor, currently 4). Assumes that this will be called
1183 // in parallel by ParallelGCThreads worker threads with discinct worker
1184 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1185 // calls will use the same "claim_value", and that that claim value is
1186 // different from the claim_value of any heap region before the start of
1187 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1188 // attempting to claim the first region in each chunk, and, if
1189 // successful, applying the closure to each region in the chunk (and
1190 // setting the claim value of the second and subsequent regions of the
1191 // chunk.) For now requires that "doHeapRegion" always returns "false",
1192 // i.e., that a closure never attempt to abort a traversal.
1193 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1194 int worker,
1195 jint claim_value);
1197 // It resets all the region claim values to the default.
1198 void reset_heap_region_claim_values();
1200 #ifdef ASSERT
1201 bool check_heap_region_claim_values(jint claim_value);
1202 #endif // ASSERT
1204 // Iterate over the regions (if any) in the current collection set.
1205 void collection_set_iterate(HeapRegionClosure* blk);
1207 // As above but starting from region r
1208 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1210 // Returns the first (lowest address) compactible space in the heap.
1211 virtual CompactibleSpace* first_compactible_space();
1213 // A CollectedHeap will contain some number of spaces. This finds the
1214 // space containing a given address, or else returns NULL.
1215 virtual Space* space_containing(const void* addr) const;
1217 // A G1CollectedHeap will contain some number of heap regions. This
1218 // finds the region containing a given address, or else returns NULL.
1219 HeapRegion* heap_region_containing(const void* addr) const;
1221 // Like the above, but requires "addr" to be in the heap (to avoid a
1222 // null-check), and unlike the above, may return an continuing humongous
1223 // region.
1224 HeapRegion* heap_region_containing_raw(const void* addr) const;
1226 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1227 // each address in the (reserved) heap is a member of exactly
1228 // one block. The defining characteristic of a block is that it is
1229 // possible to find its size, and thus to progress forward to the next
1230 // block. (Blocks may be of different sizes.) Thus, blocks may
1231 // represent Java objects, or they might be free blocks in a
1232 // free-list-based heap (or subheap), as long as the two kinds are
1233 // distinguishable and the size of each is determinable.
1235 // Returns the address of the start of the "block" that contains the
1236 // address "addr". We say "blocks" instead of "object" since some heaps
1237 // may not pack objects densely; a chunk may either be an object or a
1238 // non-object.
1239 virtual HeapWord* block_start(const void* addr) const;
1241 // Requires "addr" to be the start of a chunk, and returns its size.
1242 // "addr + size" is required to be the start of a new chunk, or the end
1243 // of the active area of the heap.
1244 virtual size_t block_size(const HeapWord* addr) const;
1246 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1247 // the block is an object.
1248 virtual bool block_is_obj(const HeapWord* addr) const;
1250 // Does this heap support heap inspection? (+PrintClassHistogram)
1251 virtual bool supports_heap_inspection() const { return true; }
1253 // Section on thread-local allocation buffers (TLABs)
1254 // See CollectedHeap for semantics.
1256 virtual bool supports_tlab_allocation() const;
1257 virtual size_t tlab_capacity(Thread* thr) const;
1258 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1260 // Can a compiler initialize a new object without store barriers?
1261 // This permission only extends from the creation of a new object
1262 // via a TLAB up to the first subsequent safepoint. If such permission
1263 // is granted for this heap type, the compiler promises to call
1264 // defer_store_barrier() below on any slow path allocation of
1265 // a new object for which such initializing store barriers will
1266 // have been elided. G1, like CMS, allows this, but should be
1267 // ready to provide a compensating write barrier as necessary
1268 // if that storage came out of a non-young region. The efficiency
1269 // of this implementation depends crucially on being able to
1270 // answer very efficiently in constant time whether a piece of
1271 // storage in the heap comes from a young region or not.
1272 // See ReduceInitialCardMarks.
1273 virtual bool can_elide_tlab_store_barriers() const {
1274 // 6920090: Temporarily disabled, because of lingering
1275 // instabilities related to RICM with G1. In the
1276 // interim, the option ReduceInitialCardMarksForG1
1277 // below is left solely as a debugging device at least
1278 // until 6920109 fixes the instabilities.
1279 return ReduceInitialCardMarksForG1;
1280 }
1282 virtual bool card_mark_must_follow_store() const {
1283 return true;
1284 }
1286 bool is_in_young(oop obj) {
1287 HeapRegion* hr = heap_region_containing(obj);
1288 return hr != NULL && hr->is_young();
1289 }
1291 // We don't need barriers for initializing stores to objects
1292 // in the young gen: for the SATB pre-barrier, there is no
1293 // pre-value that needs to be remembered; for the remembered-set
1294 // update logging post-barrier, we don't maintain remembered set
1295 // information for young gen objects. Note that non-generational
1296 // G1 does not have any "young" objects, should not elide
1297 // the rs logging barrier and so should always answer false below.
1298 // However, non-generational G1 (-XX:-G1Gen) appears to have
1299 // bit-rotted so was not tested below.
1300 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1301 // Re 6920090, 6920109 above.
1302 assert(ReduceInitialCardMarksForG1, "Else cannot be here");
1303 assert(G1Gen || !is_in_young(new_obj),
1304 "Non-generational G1 should never return true below");
1305 return is_in_young(new_obj);
1306 }
1308 // Can a compiler elide a store barrier when it writes
1309 // a permanent oop into the heap? Applies when the compiler
1310 // is storing x to the heap, where x->is_perm() is true.
1311 virtual bool can_elide_permanent_oop_store_barriers() const {
1312 // At least until perm gen collection is also G1-ified, at
1313 // which point this should return false.
1314 return true;
1315 }
1317 virtual bool allocs_are_zero_filled();
1319 // The boundary between a "large" and "small" array of primitives, in
1320 // words.
1321 virtual size_t large_typearray_limit();
1323 // Returns "true" iff the given word_size is "very large".
1324 static bool isHumongous(size_t word_size) {
1325 // Note this has to be strictly greater-than as the TLABs
1326 // are capped at the humongous thresold and we want to
1327 // ensure that we don't try to allocate a TLAB as
1328 // humongous and that we don't allocate a humongous
1329 // object in a TLAB.
1330 return word_size > _humongous_object_threshold_in_words;
1331 }
1333 // Update mod union table with the set of dirty cards.
1334 void updateModUnion();
1336 // Set the mod union bits corresponding to the given memRegion. Note
1337 // that this is always a safe operation, since it doesn't clear any
1338 // bits.
1339 void markModUnionRange(MemRegion mr);
1341 // Records the fact that a marking phase is no longer in progress.
1342 void set_marking_complete() {
1343 _mark_in_progress = false;
1344 }
1345 void set_marking_started() {
1346 _mark_in_progress = true;
1347 }
1348 bool mark_in_progress() {
1349 return _mark_in_progress;
1350 }
1352 // Print the maximum heap capacity.
1353 virtual size_t max_capacity() const;
1355 virtual jlong millis_since_last_gc();
1357 // Perform any cleanup actions necessary before allowing a verification.
1358 virtual void prepare_for_verify();
1360 // Perform verification.
1362 // use_prev_marking == true -> use "prev" marking information,
1363 // use_prev_marking == false -> use "next" marking information
1364 // NOTE: Only the "prev" marking information is guaranteed to be
1365 // consistent most of the time, so most calls to this should use
1366 // use_prev_marking == true. Currently, there is only one case where
1367 // this is called with use_prev_marking == false, which is to verify
1368 // the "next" marking information at the end of remark.
1369 void verify(bool allow_dirty, bool silent, bool use_prev_marking);
1371 // Override; it uses the "prev" marking information
1372 virtual void verify(bool allow_dirty, bool silent);
1373 // Default behavior by calling print(tty);
1374 virtual void print() const;
1375 // This calls print_on(st, PrintHeapAtGCExtended).
1376 virtual void print_on(outputStream* st) const;
1377 // If extended is true, it will print out information for all
1378 // regions in the heap by calling print_on_extended(st).
1379 virtual void print_on(outputStream* st, bool extended) const;
1380 virtual void print_on_extended(outputStream* st) const;
1382 virtual void print_gc_threads_on(outputStream* st) const;
1383 virtual void gc_threads_do(ThreadClosure* tc) const;
1385 // Override
1386 void print_tracing_info() const;
1388 // If "addr" is a pointer into the (reserved?) heap, returns a positive
1389 // number indicating the "arena" within the heap in which "addr" falls.
1390 // Or else returns 0.
1391 virtual int addr_to_arena_id(void* addr) const;
1393 // Convenience function to be used in situations where the heap type can be
1394 // asserted to be this type.
1395 static G1CollectedHeap* heap();
1397 void empty_young_list();
1399 void set_region_short_lived_locked(HeapRegion* hr);
1400 // add appropriate methods for any other surv rate groups
1402 YoungList* young_list() { return _young_list; }
1404 // debugging
1405 bool check_young_list_well_formed() {
1406 return _young_list->check_list_well_formed();
1407 }
1409 bool check_young_list_empty(bool check_heap,
1410 bool check_sample = true);
1412 // *** Stuff related to concurrent marking. It's not clear to me that so
1413 // many of these need to be public.
1415 // The functions below are helper functions that a subclass of
1416 // "CollectedHeap" can use in the implementation of its virtual
1417 // functions.
1418 // This performs a concurrent marking of the live objects in a
1419 // bitmap off to the side.
1420 void doConcurrentMark();
1422 // This is called from the marksweep collector which then does
1423 // a concurrent mark and verifies that the results agree with
1424 // the stop the world marking.
1425 void checkConcurrentMark();
1426 void do_sync_mark();
1428 bool isMarkedPrev(oop obj) const;
1429 bool isMarkedNext(oop obj) const;
1431 // use_prev_marking == true -> use "prev" marking information,
1432 // use_prev_marking == false -> use "next" marking information
1433 bool is_obj_dead_cond(const oop obj,
1434 const HeapRegion* hr,
1435 const bool use_prev_marking) const {
1436 if (use_prev_marking) {
1437 return is_obj_dead(obj, hr);
1438 } else {
1439 return is_obj_ill(obj, hr);
1440 }
1441 }
1443 // Determine if an object is dead, given the object and also
1444 // the region to which the object belongs. An object is dead
1445 // iff a) it was not allocated since the last mark and b) it
1446 // is not marked.
1448 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1449 return
1450 !hr->obj_allocated_since_prev_marking(obj) &&
1451 !isMarkedPrev(obj);
1452 }
1454 // This is used when copying an object to survivor space.
1455 // If the object is marked live, then we mark the copy live.
1456 // If the object is allocated since the start of this mark
1457 // cycle, then we mark the copy live.
1458 // If the object has been around since the previous mark
1459 // phase, and hasn't been marked yet during this phase,
1460 // then we don't mark it, we just wait for the
1461 // current marking cycle to get to it.
1463 // This function returns true when an object has been
1464 // around since the previous marking and hasn't yet
1465 // been marked during this marking.
1467 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1468 return
1469 !hr->obj_allocated_since_next_marking(obj) &&
1470 !isMarkedNext(obj);
1471 }
1473 // Determine if an object is dead, given only the object itself.
1474 // This will find the region to which the object belongs and
1475 // then call the region version of the same function.
1477 // Added if it is in permanent gen it isn't dead.
1478 // Added if it is NULL it isn't dead.
1480 // use_prev_marking == true -> use "prev" marking information,
1481 // use_prev_marking == false -> use "next" marking information
1482 bool is_obj_dead_cond(const oop obj,
1483 const bool use_prev_marking) {
1484 if (use_prev_marking) {
1485 return is_obj_dead(obj);
1486 } else {
1487 return is_obj_ill(obj);
1488 }
1489 }
1491 bool is_obj_dead(const oop obj) {
1492 const HeapRegion* hr = heap_region_containing(obj);
1493 if (hr == NULL) {
1494 if (Universe::heap()->is_in_permanent(obj))
1495 return false;
1496 else if (obj == NULL) return false;
1497 else return true;
1498 }
1499 else return is_obj_dead(obj, hr);
1500 }
1502 bool is_obj_ill(const oop obj) {
1503 const HeapRegion* hr = heap_region_containing(obj);
1504 if (hr == NULL) {
1505 if (Universe::heap()->is_in_permanent(obj))
1506 return false;
1507 else if (obj == NULL) return false;
1508 else return true;
1509 }
1510 else return is_obj_ill(obj, hr);
1511 }
1513 // The following is just to alert the verification code
1514 // that a full collection has occurred and that the
1515 // remembered sets are no longer up to date.
1516 bool _full_collection;
1517 void set_full_collection() { _full_collection = true;}
1518 void clear_full_collection() {_full_collection = false;}
1519 bool full_collection() {return _full_collection;}
1521 ConcurrentMark* concurrent_mark() const { return _cm; }
1522 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1524 // The dirty cards region list is used to record a subset of regions
1525 // whose cards need clearing. The list if populated during the
1526 // remembered set scanning and drained during the card table
1527 // cleanup. Although the methods are reentrant, population/draining
1528 // phases must not overlap. For synchronization purposes the last
1529 // element on the list points to itself.
1530 HeapRegion* _dirty_cards_region_list;
1531 void push_dirty_cards_region(HeapRegion* hr);
1532 HeapRegion* pop_dirty_cards_region();
1534 public:
1535 void stop_conc_gc_threads();
1537 // <NEW PREDICTION>
1539 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1540 void check_if_region_is_too_expensive(double predicted_time_ms);
1541 size_t pending_card_num();
1542 size_t max_pending_card_num();
1543 size_t cards_scanned();
1545 // </NEW PREDICTION>
1547 protected:
1548 size_t _max_heap_capacity;
1550 public:
1551 // Temporary: call to mark things unimplemented for the G1 heap (e.g.,
1552 // MemoryService). In productization, we can make this assert false
1553 // to catch such places (as well as searching for calls to this...)
1554 static void g1_unimplemented();
1556 };
1558 #define use_local_bitmaps 1
1559 #define verify_local_bitmaps 0
1560 #define oop_buffer_length 256
1562 #ifndef PRODUCT
1563 class GCLabBitMap;
1564 class GCLabBitMapClosure: public BitMapClosure {
1565 private:
1566 ConcurrentMark* _cm;
1567 GCLabBitMap* _bitmap;
1569 public:
1570 GCLabBitMapClosure(ConcurrentMark* cm,
1571 GCLabBitMap* bitmap) {
1572 _cm = cm;
1573 _bitmap = bitmap;
1574 }
1576 virtual bool do_bit(size_t offset);
1577 };
1578 #endif // !PRODUCT
1580 class GCLabBitMap: public BitMap {
1581 private:
1582 ConcurrentMark* _cm;
1584 int _shifter;
1585 size_t _bitmap_word_covers_words;
1587 // beginning of the heap
1588 HeapWord* _heap_start;
1590 // this is the actual start of the GCLab
1591 HeapWord* _real_start_word;
1593 // this is the actual end of the GCLab
1594 HeapWord* _real_end_word;
1596 // this is the first word, possibly located before the actual start
1597 // of the GCLab, that corresponds to the first bit of the bitmap
1598 HeapWord* _start_word;
1600 // size of a GCLab in words
1601 size_t _gclab_word_size;
1603 static int shifter() {
1604 return MinObjAlignment - 1;
1605 }
1607 // how many heap words does a single bitmap word corresponds to?
1608 static size_t bitmap_word_covers_words() {
1609 return BitsPerWord << shifter();
1610 }
1612 size_t gclab_word_size() const {
1613 return _gclab_word_size;
1614 }
1616 // Calculates actual GCLab size in words
1617 size_t gclab_real_word_size() const {
1618 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1619 / BitsPerWord;
1620 }
1622 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1623 size_t bits_in_bitmap = gclab_word_size >> shifter();
1624 // We are going to ensure that the beginning of a word in this
1625 // bitmap also corresponds to the beginning of a word in the
1626 // global marking bitmap. To handle the case where a GCLab
1627 // starts from the middle of the bitmap, we need to add enough
1628 // space (i.e. up to a bitmap word) to ensure that we have
1629 // enough bits in the bitmap.
1630 return bits_in_bitmap + BitsPerWord - 1;
1631 }
1632 public:
1633 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1634 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1635 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1636 _shifter(shifter()),
1637 _bitmap_word_covers_words(bitmap_word_covers_words()),
1638 _heap_start(heap_start),
1639 _gclab_word_size(gclab_word_size),
1640 _real_start_word(NULL),
1641 _real_end_word(NULL),
1642 _start_word(NULL)
1643 {
1644 guarantee( size_in_words() >= bitmap_size_in_words(),
1645 "just making sure");
1646 }
1648 inline unsigned heapWordToOffset(HeapWord* addr) {
1649 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1650 assert(offset < size(), "offset should be within bounds");
1651 return offset;
1652 }
1654 inline HeapWord* offsetToHeapWord(size_t offset) {
1655 HeapWord* addr = _start_word + (offset << _shifter);
1656 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1657 return addr;
1658 }
1660 bool fields_well_formed() {
1661 bool ret1 = (_real_start_word == NULL) &&
1662 (_real_end_word == NULL) &&
1663 (_start_word == NULL);
1664 if (ret1)
1665 return true;
1667 bool ret2 = _real_start_word >= _start_word &&
1668 _start_word < _real_end_word &&
1669 (_real_start_word + _gclab_word_size) == _real_end_word &&
1670 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1671 > _real_end_word;
1672 return ret2;
1673 }
1675 inline bool mark(HeapWord* addr) {
1676 guarantee(use_local_bitmaps, "invariant");
1677 assert(fields_well_formed(), "invariant");
1679 if (addr >= _real_start_word && addr < _real_end_word) {
1680 assert(!isMarked(addr), "should not have already been marked");
1682 // first mark it on the bitmap
1683 at_put(heapWordToOffset(addr), true);
1685 return true;
1686 } else {
1687 return false;
1688 }
1689 }
1691 inline bool isMarked(HeapWord* addr) {
1692 guarantee(use_local_bitmaps, "invariant");
1693 assert(fields_well_formed(), "invariant");
1695 return at(heapWordToOffset(addr));
1696 }
1698 void set_buffer(HeapWord* start) {
1699 guarantee(use_local_bitmaps, "invariant");
1700 clear();
1702 assert(start != NULL, "invariant");
1703 _real_start_word = start;
1704 _real_end_word = start + _gclab_word_size;
1706 size_t diff =
1707 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1708 _start_word = start - diff;
1710 assert(fields_well_formed(), "invariant");
1711 }
1713 #ifndef PRODUCT
1714 void verify() {
1715 // verify that the marks have been propagated
1716 GCLabBitMapClosure cl(_cm, this);
1717 iterate(&cl);
1718 }
1719 #endif // PRODUCT
1721 void retire() {
1722 guarantee(use_local_bitmaps, "invariant");
1723 assert(fields_well_formed(), "invariant");
1725 if (_start_word != NULL) {
1726 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1728 // this means that the bitmap was set up for the GCLab
1729 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1731 mark_bitmap->mostly_disjoint_range_union(this,
1732 0, // always start from the start of the bitmap
1733 _start_word,
1734 gclab_real_word_size());
1735 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1737 #ifndef PRODUCT
1738 if (use_local_bitmaps && verify_local_bitmaps)
1739 verify();
1740 #endif // PRODUCT
1741 } else {
1742 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1743 }
1744 }
1746 size_t bitmap_size_in_words() const {
1747 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1748 }
1750 };
1752 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1753 private:
1754 bool _retired;
1755 bool _during_marking;
1756 GCLabBitMap _bitmap;
1758 public:
1759 G1ParGCAllocBuffer(size_t gclab_word_size) :
1760 ParGCAllocBuffer(gclab_word_size),
1761 _during_marking(G1CollectedHeap::heap()->mark_in_progress()),
1762 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
1763 _retired(false)
1764 { }
1766 inline bool mark(HeapWord* addr) {
1767 guarantee(use_local_bitmaps, "invariant");
1768 assert(_during_marking, "invariant");
1769 return _bitmap.mark(addr);
1770 }
1772 inline void set_buf(HeapWord* buf) {
1773 if (use_local_bitmaps && _during_marking)
1774 _bitmap.set_buffer(buf);
1775 ParGCAllocBuffer::set_buf(buf);
1776 _retired = false;
1777 }
1779 inline void retire(bool end_of_gc, bool retain) {
1780 if (_retired)
1781 return;
1782 if (use_local_bitmaps && _during_marking) {
1783 _bitmap.retire();
1784 }
1785 ParGCAllocBuffer::retire(end_of_gc, retain);
1786 _retired = true;
1787 }
1788 };
1790 class G1ParScanThreadState : public StackObj {
1791 protected:
1792 G1CollectedHeap* _g1h;
1793 RefToScanQueue* _refs;
1794 DirtyCardQueue _dcq;
1795 CardTableModRefBS* _ct_bs;
1796 G1RemSet* _g1_rem;
1798 G1ParGCAllocBuffer _surviving_alloc_buffer;
1799 G1ParGCAllocBuffer _tenured_alloc_buffer;
1800 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1801 ageTable _age_table;
1803 size_t _alloc_buffer_waste;
1804 size_t _undo_waste;
1806 OopsInHeapRegionClosure* _evac_failure_cl;
1807 G1ParScanHeapEvacClosure* _evac_cl;
1808 G1ParScanPartialArrayClosure* _partial_scan_cl;
1810 int _hash_seed;
1811 int _queue_num;
1813 size_t _term_attempts;
1815 double _start;
1816 double _start_strong_roots;
1817 double _strong_roots_time;
1818 double _start_term;
1819 double _term_time;
1821 // Map from young-age-index (0 == not young, 1 is youngest) to
1822 // surviving words. base is what we get back from the malloc call
1823 size_t* _surviving_young_words_base;
1824 // this points into the array, as we use the first few entries for padding
1825 size_t* _surviving_young_words;
1827 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1829 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1831 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1833 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1834 CardTableModRefBS* ctbs() { return _ct_bs; }
1836 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1837 if (!from->is_survivor()) {
1838 _g1_rem->par_write_ref(from, p, tid);
1839 }
1840 }
1842 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1843 // If the new value of the field points to the same region or
1844 // is the to-space, we don't need to include it in the Rset updates.
1845 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1846 size_t card_index = ctbs()->index_for(p);
1847 // If the card hasn't been added to the buffer, do it.
1848 if (ctbs()->mark_card_deferred(card_index)) {
1849 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1850 }
1851 }
1852 }
1854 public:
1855 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1857 ~G1ParScanThreadState() {
1858 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1859 }
1861 RefToScanQueue* refs() { return _refs; }
1862 ageTable* age_table() { return &_age_table; }
1864 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1865 return _alloc_buffers[purpose];
1866 }
1868 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1869 size_t undo_waste() const { return _undo_waste; }
1871 #ifdef ASSERT
1872 bool verify_ref(narrowOop* ref) const;
1873 bool verify_ref(oop* ref) const;
1874 bool verify_task(StarTask ref) const;
1875 #endif // ASSERT
1877 template <class T> void push_on_queue(T* ref) {
1878 assert(verify_ref(ref), "sanity");
1879 refs()->push(ref);
1880 }
1882 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1883 if (G1DeferredRSUpdate) {
1884 deferred_rs_update(from, p, tid);
1885 } else {
1886 immediate_rs_update(from, p, tid);
1887 }
1888 }
1890 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1892 HeapWord* obj = NULL;
1893 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1894 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1895 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1896 assert(gclab_word_size == alloc_buf->word_sz(),
1897 "dynamic resizing is not supported");
1898 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1899 alloc_buf->retire(false, false);
1901 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1902 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1903 // Otherwise.
1904 alloc_buf->set_buf(buf);
1906 obj = alloc_buf->allocate(word_sz);
1907 assert(obj != NULL, "buffer was definitely big enough...");
1908 } else {
1909 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1910 }
1911 return obj;
1912 }
1914 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1915 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1916 if (obj != NULL) return obj;
1917 return allocate_slow(purpose, word_sz);
1918 }
1920 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
1921 if (alloc_buffer(purpose)->contains(obj)) {
1922 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
1923 "should contain whole object");
1924 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
1925 } else {
1926 CollectedHeap::fill_with_object(obj, word_sz);
1927 add_to_undo_waste(word_sz);
1928 }
1929 }
1931 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
1932 _evac_failure_cl = evac_failure_cl;
1933 }
1934 OopsInHeapRegionClosure* evac_failure_closure() {
1935 return _evac_failure_cl;
1936 }
1938 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
1939 _evac_cl = evac_cl;
1940 }
1942 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
1943 _partial_scan_cl = partial_scan_cl;
1944 }
1946 int* hash_seed() { return &_hash_seed; }
1947 int queue_num() { return _queue_num; }
1949 size_t term_attempts() const { return _term_attempts; }
1950 void note_term_attempt() { _term_attempts++; }
1952 void start_strong_roots() {
1953 _start_strong_roots = os::elapsedTime();
1954 }
1955 void end_strong_roots() {
1956 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
1957 }
1958 double strong_roots_time() const { return _strong_roots_time; }
1960 void start_term_time() {
1961 note_term_attempt();
1962 _start_term = os::elapsedTime();
1963 }
1964 void end_term_time() {
1965 _term_time += (os::elapsedTime() - _start_term);
1966 }
1967 double term_time() const { return _term_time; }
1969 double elapsed_time() const {
1970 return os::elapsedTime() - _start;
1971 }
1973 static void
1974 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
1975 void
1976 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
1978 size_t* surviving_young_words() {
1979 // We add on to hide entry 0 which accumulates surviving words for
1980 // age -1 regions (i.e. non-young ones)
1981 return _surviving_young_words;
1982 }
1984 void retire_alloc_buffers() {
1985 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1986 size_t waste = _alloc_buffers[ap]->words_remaining();
1987 add_to_alloc_buffer_waste(waste);
1988 _alloc_buffers[ap]->retire(true, false);
1989 }
1990 }
1992 template <class T> void deal_with_reference(T* ref_to_scan) {
1993 if (has_partial_array_mask(ref_to_scan)) {
1994 _partial_scan_cl->do_oop_nv(ref_to_scan);
1995 } else {
1996 // Note: we can use "raw" versions of "region_containing" because
1997 // "obj_to_scan" is definitely in the heap, and is not in a
1998 // humongous region.
1999 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2000 _evac_cl->set_region(r);
2001 _evac_cl->do_oop_nv(ref_to_scan);
2002 }
2003 }
2005 void deal_with_reference(StarTask ref) {
2006 assert(verify_task(ref), "sanity");
2007 if (ref.is_narrow()) {
2008 deal_with_reference((narrowOop*)ref);
2009 } else {
2010 deal_with_reference((oop*)ref);
2011 }
2012 }
2014 public:
2015 void trim_queue();
2016 };
2018 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP