Thu, 17 Nov 2011 12:40:15 -0800
7112743: G1: Reduce overhead of marking closure during evacuation pauses
Summary: Parallelize the serial code that was used to mark objects reachable from survivor objects in the collection set. Some minor improvments in the timers used to track the freeing of the collection set along with some tweaks to PrintGCDetails.
Reviewed-by: tonyp, brutisso
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/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1HRPrinter.hpp"
31 #include "gc_implementation/g1/g1RemSet.hpp"
32 #include "gc_implementation/g1/g1MonitoringSupport.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.hpp"
34 #include "gc_implementation/g1/heapRegionSets.hpp"
35 #include "gc_implementation/shared/hSpaceCounters.hpp"
36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp"
37 #include "memory/barrierSet.hpp"
38 #include "memory/memRegion.hpp"
39 #include "memory/sharedHeap.hpp"
41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
42 // It uses the "Garbage First" heap organization and algorithm, which
43 // may combine concurrent marking with parallel, incremental compaction of
44 // heap subsets that will yield large amounts of garbage.
46 class HeapRegion;
47 class HRRSCleanupTask;
48 class PermanentGenerationSpec;
49 class GenerationSpec;
50 class OopsInHeapRegionClosure;
51 class G1ScanHeapEvacClosure;
52 class ObjectClosure;
53 class SpaceClosure;
54 class CompactibleSpaceClosure;
55 class Space;
56 class G1CollectorPolicy;
57 class GenRemSet;
58 class G1RemSet;
59 class HeapRegionRemSetIterator;
60 class ConcurrentMark;
61 class ConcurrentMarkThread;
62 class ConcurrentG1Refine;
63 class GenerationCounters;
65 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
77 class YoungList : public CHeapObj {
78 private:
79 G1CollectedHeap* _g1h;
81 HeapRegion* _head;
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
86 HeapRegion* _curr;
88 size_t _length;
89 size_t _survivor_length;
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
94 void empty_list(HeapRegion* list);
96 public:
97 YoungList(G1CollectedHeap* g1h);
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
102 void empty_list();
103 bool is_empty() { return _length == 0; }
104 size_t length() { return _length; }
105 size_t survivor_length() { return _survivor_length; }
107 // Currently we do not keep track of the used byte sum for the
108 // young list and the survivors and it'd be quite a lot of work to
109 // do so. When we'll eventually replace the young list with
110 // instances of HeapRegionLinkedList we'll get that for free. So,
111 // we'll report the more accurate information then.
112 size_t eden_used_bytes() {
113 assert(length() >= survivor_length(), "invariant");
114 return (length() - survivor_length()) * HeapRegion::GrainBytes;
115 }
116 size_t survivor_used_bytes() {
117 return survivor_length() * HeapRegion::GrainBytes;
118 }
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
149 class MutatorAllocRegion : public G1AllocRegion {
150 protected:
151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
153 public:
154 MutatorAllocRegion()
155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
156 };
158 // The G1 STW is alive closure.
159 // An instance is embedded into the G1CH and used as the
160 // (optional) _is_alive_non_header closure in the STW
161 // reference processor. It is also extensively used during
162 // refence processing during STW evacuation pauses.
163 class G1STWIsAliveClosure: public BoolObjectClosure {
164 G1CollectedHeap* _g1;
165 public:
166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
167 void do_object(oop p) { assert(false, "Do not call."); }
168 bool do_object_b(oop p);
169 };
171 class SurvivorGCAllocRegion : public G1AllocRegion {
172 protected:
173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
175 public:
176 SurvivorGCAllocRegion()
177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
178 };
180 class OldGCAllocRegion : public G1AllocRegion {
181 protected:
182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
184 public:
185 OldGCAllocRegion()
186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
187 };
189 class RefineCardTableEntryClosure;
191 class G1CollectedHeap : public SharedHeap {
192 friend class VM_G1CollectForAllocation;
193 friend class VM_GenCollectForPermanentAllocation;
194 friend class VM_G1CollectFull;
195 friend class VM_G1IncCollectionPause;
196 friend class VMStructs;
197 friend class MutatorAllocRegion;
198 friend class SurvivorGCAllocRegion;
199 friend class OldGCAllocRegion;
201 // Closures used in implementation.
202 friend class G1ParCopyHelper;
203 friend class G1IsAliveClosure;
204 friend class G1EvacuateFollowersClosure;
205 friend class G1ParScanThreadState;
206 friend class G1ParScanClosureSuper;
207 friend class G1ParEvacuateFollowersClosure;
208 friend class G1ParTask;
209 friend class G1FreeGarbageRegionClosure;
210 friend class RefineCardTableEntryClosure;
211 friend class G1PrepareCompactClosure;
212 friend class RegionSorter;
213 friend class RegionResetter;
214 friend class CountRCClosure;
215 friend class EvacPopObjClosure;
216 friend class G1ParCleanupCTTask;
218 // Other related classes.
219 friend class G1MarkSweep;
221 private:
222 // The one and only G1CollectedHeap, so static functions can find it.
223 static G1CollectedHeap* _g1h;
225 static size_t _humongous_object_threshold_in_words;
227 // Storage for the G1 heap (excludes the permanent generation).
228 VirtualSpace _g1_storage;
229 MemRegion _g1_reserved;
231 // The part of _g1_storage that is currently committed.
232 MemRegion _g1_committed;
234 // The master free list. It will satisfy all new region allocations.
235 MasterFreeRegionList _free_list;
237 // The secondary free list which contains regions that have been
238 // freed up during the cleanup process. This will be appended to the
239 // master free list when appropriate.
240 SecondaryFreeRegionList _secondary_free_list;
242 // It keeps track of the old regions.
243 MasterOldRegionSet _old_set;
245 // It keeps track of the humongous regions.
246 MasterHumongousRegionSet _humongous_set;
248 // The number of regions we could create by expansion.
249 size_t _expansion_regions;
251 // The block offset table for the G1 heap.
252 G1BlockOffsetSharedArray* _bot_shared;
254 // Tears down the region sets / lists so that they are empty and the
255 // regions on the heap do not belong to a region set / list. The
256 // only exception is the humongous set which we leave unaltered. If
257 // free_list_only is true, it will only tear down the master free
258 // list. It is called before a Full GC (free_list_only == false) or
259 // before heap shrinking (free_list_only == true).
260 void tear_down_region_sets(bool free_list_only);
262 // Rebuilds the region sets / lists so that they are repopulated to
263 // reflect the contents of the heap. The only exception is the
264 // humongous set which was not torn down in the first place. If
265 // free_list_only is true, it will only rebuild the master free
266 // list. It is called after a Full GC (free_list_only == false) or
267 // after heap shrinking (free_list_only == true).
268 void rebuild_region_sets(bool free_list_only);
270 // The sequence of all heap regions in the heap.
271 HeapRegionSeq _hrs;
273 // Alloc region used to satisfy mutator allocation requests.
274 MutatorAllocRegion _mutator_alloc_region;
276 // Alloc region used to satisfy allocation requests by the GC for
277 // survivor objects.
278 SurvivorGCAllocRegion _survivor_gc_alloc_region;
280 // Alloc region used to satisfy allocation requests by the GC for
281 // old objects.
282 OldGCAllocRegion _old_gc_alloc_region;
284 // The last old region we allocated to during the last GC.
285 // Typically, it is not full so we should re-use it during the next GC.
286 HeapRegion* _retained_old_gc_alloc_region;
288 // It resets the mutator alloc region before new allocations can take place.
289 void init_mutator_alloc_region();
291 // It releases the mutator alloc region.
292 void release_mutator_alloc_region();
294 // It initializes the GC alloc regions at the start of a GC.
295 void init_gc_alloc_regions();
297 // It releases the GC alloc regions at the end of a GC.
298 void release_gc_alloc_regions();
300 // It does any cleanup that needs to be done on the GC alloc regions
301 // before a Full GC.
302 void abandon_gc_alloc_regions();
304 // Helper for monitoring and management support.
305 G1MonitoringSupport* _g1mm;
307 // Determines PLAB size for a particular allocation purpose.
308 static size_t desired_plab_sz(GCAllocPurpose purpose);
310 // Outside of GC pauses, the number of bytes used in all regions other
311 // than the current allocation region.
312 size_t _summary_bytes_used;
314 // This is used for a quick test on whether a reference points into
315 // the collection set or not. Basically, we have an array, with one
316 // byte per region, and that byte denotes whether the corresponding
317 // region is in the collection set or not. The entry corresponding
318 // the bottom of the heap, i.e., region 0, is pointed to by
319 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
320 // biased so that it actually points to address 0 of the address
321 // space, to make the test as fast as possible (we can simply shift
322 // the address to address into it, instead of having to subtract the
323 // bottom of the heap from the address before shifting it; basically
324 // it works in the same way the card table works).
325 bool* _in_cset_fast_test;
327 // The allocated array used for the fast test on whether a reference
328 // points into the collection set or not. This field is also used to
329 // free the array.
330 bool* _in_cset_fast_test_base;
332 // The length of the _in_cset_fast_test_base array.
333 size_t _in_cset_fast_test_length;
335 volatile unsigned _gc_time_stamp;
337 size_t* _surviving_young_words;
339 G1HRPrinter _hr_printer;
341 void setup_surviving_young_words();
342 void update_surviving_young_words(size_t* surv_young_words);
343 void cleanup_surviving_young_words();
345 // It decides whether an explicit GC should start a concurrent cycle
346 // instead of doing a STW GC. Currently, a concurrent cycle is
347 // explicitly started if:
348 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
349 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
350 bool should_do_concurrent_full_gc(GCCause::Cause cause);
352 // Keeps track of how many "full collections" (i.e., Full GCs or
353 // concurrent cycles) we have completed. The number of them we have
354 // started is maintained in _total_full_collections in CollectedHeap.
355 volatile unsigned int _full_collections_completed;
357 // This is a non-product method that is helpful for testing. It is
358 // called at the end of a GC and artificially expands the heap by
359 // allocating a number of dead regions. This way we can induce very
360 // frequent marking cycles and stress the cleanup / concurrent
361 // cleanup code more (as all the regions that will be allocated by
362 // this method will be found dead by the marking cycle).
363 void allocate_dummy_regions() PRODUCT_RETURN;
365 // These are macros so that, if the assert fires, we get the correct
366 // line number, file, etc.
368 #define heap_locking_asserts_err_msg(_extra_message_) \
369 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
370 (_extra_message_), \
371 BOOL_TO_STR(Heap_lock->owned_by_self()), \
372 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
373 BOOL_TO_STR(Thread::current()->is_VM_thread()))
375 #define assert_heap_locked() \
376 do { \
377 assert(Heap_lock->owned_by_self(), \
378 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
379 } while (0)
381 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
382 do { \
383 assert(Heap_lock->owned_by_self() || \
384 (SafepointSynchronize::is_at_safepoint() && \
385 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
386 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
387 "should be at a safepoint")); \
388 } while (0)
390 #define assert_heap_locked_and_not_at_safepoint() \
391 do { \
392 assert(Heap_lock->owned_by_self() && \
393 !SafepointSynchronize::is_at_safepoint(), \
394 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
395 "should not be at a safepoint")); \
396 } while (0)
398 #define assert_heap_not_locked() \
399 do { \
400 assert(!Heap_lock->owned_by_self(), \
401 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
402 } while (0)
404 #define assert_heap_not_locked_and_not_at_safepoint() \
405 do { \
406 assert(!Heap_lock->owned_by_self() && \
407 !SafepointSynchronize::is_at_safepoint(), \
408 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
409 "should not be at a safepoint")); \
410 } while (0)
412 #define assert_at_safepoint(_should_be_vm_thread_) \
413 do { \
414 assert(SafepointSynchronize::is_at_safepoint() && \
415 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
416 heap_locking_asserts_err_msg("should be at a safepoint")); \
417 } while (0)
419 #define assert_not_at_safepoint() \
420 do { \
421 assert(!SafepointSynchronize::is_at_safepoint(), \
422 heap_locking_asserts_err_msg("should not be at a safepoint")); \
423 } while (0)
425 protected:
427 // The young region list.
428 YoungList* _young_list;
430 // The current policy object for the collector.
431 G1CollectorPolicy* _g1_policy;
433 // This is the second level of trying to allocate a new region. If
434 // new_region() didn't find a region on the free_list, this call will
435 // check whether there's anything available on the
436 // secondary_free_list and/or wait for more regions to appear on
437 // that list, if _free_regions_coming is set.
438 HeapRegion* new_region_try_secondary_free_list();
440 // Try to allocate a single non-humongous HeapRegion sufficient for
441 // an allocation of the given word_size. If do_expand is true,
442 // attempt to expand the heap if necessary to satisfy the allocation
443 // request.
444 HeapRegion* new_region(size_t word_size, bool do_expand);
446 // Attempt to satisfy a humongous allocation request of the given
447 // size by finding a contiguous set of free regions of num_regions
448 // length and remove them from the master free list. Return the
449 // index of the first region or G1_NULL_HRS_INDEX if the search
450 // was unsuccessful.
451 size_t humongous_obj_allocate_find_first(size_t num_regions,
452 size_t word_size);
454 // Initialize a contiguous set of free regions of length num_regions
455 // and starting at index first so that they appear as a single
456 // humongous region.
457 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
458 size_t num_regions,
459 size_t word_size);
461 // Attempt to allocate a humongous object of the given size. Return
462 // NULL if unsuccessful.
463 HeapWord* humongous_obj_allocate(size_t word_size);
465 // The following two methods, allocate_new_tlab() and
466 // mem_allocate(), are the two main entry points from the runtime
467 // into the G1's allocation routines. They have the following
468 // assumptions:
469 //
470 // * They should both be called outside safepoints.
471 //
472 // * They should both be called without holding the Heap_lock.
473 //
474 // * All allocation requests for new TLABs should go to
475 // allocate_new_tlab().
476 //
477 // * All non-TLAB allocation requests should go to mem_allocate().
478 //
479 // * If either call cannot satisfy the allocation request using the
480 // current allocating region, they will try to get a new one. If
481 // this fails, they will attempt to do an evacuation pause and
482 // retry the allocation.
483 //
484 // * If all allocation attempts fail, even after trying to schedule
485 // an evacuation pause, allocate_new_tlab() will return NULL,
486 // whereas mem_allocate() will attempt a heap expansion and/or
487 // schedule a Full GC.
488 //
489 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
490 // should never be called with word_size being humongous. All
491 // humongous allocation requests should go to mem_allocate() which
492 // will satisfy them with a special path.
494 virtual HeapWord* allocate_new_tlab(size_t word_size);
496 virtual HeapWord* mem_allocate(size_t word_size,
497 bool* gc_overhead_limit_was_exceeded);
499 // The following three methods take a gc_count_before_ret
500 // parameter which is used to return the GC count if the method
501 // returns NULL. Given that we are required to read the GC count
502 // while holding the Heap_lock, and these paths will take the
503 // Heap_lock at some point, it's easier to get them to read the GC
504 // count while holding the Heap_lock before they return NULL instead
505 // of the caller (namely: mem_allocate()) having to also take the
506 // Heap_lock just to read the GC count.
508 // First-level mutator allocation attempt: try to allocate out of
509 // the mutator alloc region without taking the Heap_lock. This
510 // should only be used for non-humongous allocations.
511 inline HeapWord* attempt_allocation(size_t word_size,
512 unsigned int* gc_count_before_ret);
514 // Second-level mutator allocation attempt: take the Heap_lock and
515 // retry the allocation attempt, potentially scheduling a GC
516 // pause. This should only be used for non-humongous allocations.
517 HeapWord* attempt_allocation_slow(size_t word_size,
518 unsigned int* gc_count_before_ret);
520 // Takes the Heap_lock and attempts a humongous allocation. It can
521 // potentially schedule a GC pause.
522 HeapWord* attempt_allocation_humongous(size_t word_size,
523 unsigned int* gc_count_before_ret);
525 // Allocation attempt that should be called during safepoints (e.g.,
526 // at the end of a successful GC). expect_null_mutator_alloc_region
527 // specifies whether the mutator alloc region is expected to be NULL
528 // or not.
529 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
530 bool expect_null_mutator_alloc_region);
532 // It dirties the cards that cover the block so that so that the post
533 // write barrier never queues anything when updating objects on this
534 // block. It is assumed (and in fact we assert) that the block
535 // belongs to a young region.
536 inline void dirty_young_block(HeapWord* start, size_t word_size);
538 // Allocate blocks during garbage collection. Will ensure an
539 // allocation region, either by picking one or expanding the
540 // heap, and then allocate a block of the given size. The block
541 // may not be a humongous - it must fit into a single heap region.
542 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
544 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
545 HeapRegion* alloc_region,
546 bool par,
547 size_t word_size);
549 // Ensure that no further allocations can happen in "r", bearing in mind
550 // that parallel threads might be attempting allocations.
551 void par_allocate_remaining_space(HeapRegion* r);
553 // Allocation attempt during GC for a survivor object / PLAB.
554 inline HeapWord* survivor_attempt_allocation(size_t word_size);
556 // Allocation attempt during GC for an old object / PLAB.
557 inline HeapWord* old_attempt_allocation(size_t word_size);
559 // These methods are the "callbacks" from the G1AllocRegion class.
561 // For mutator alloc regions.
562 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
563 void retire_mutator_alloc_region(HeapRegion* alloc_region,
564 size_t allocated_bytes);
566 // For GC alloc regions.
567 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
568 GCAllocPurpose ap);
569 void retire_gc_alloc_region(HeapRegion* alloc_region,
570 size_t allocated_bytes, GCAllocPurpose ap);
572 // - if explicit_gc is true, the GC is for a System.gc() or a heap
573 // inspection request and should collect the entire heap
574 // - if clear_all_soft_refs is true, all soft references should be
575 // cleared during the GC
576 // - if explicit_gc is false, word_size describes the allocation that
577 // the GC should attempt (at least) to satisfy
578 // - it returns false if it is unable to do the collection due to the
579 // GC locker being active, true otherwise
580 bool do_collection(bool explicit_gc,
581 bool clear_all_soft_refs,
582 size_t word_size);
584 // Callback from VM_G1CollectFull operation.
585 // Perform a full collection.
586 void do_full_collection(bool clear_all_soft_refs);
588 // Resize the heap if necessary after a full collection. If this is
589 // after a collect-for allocation, "word_size" is the allocation size,
590 // and will be considered part of the used portion of the heap.
591 void resize_if_necessary_after_full_collection(size_t word_size);
593 // Callback from VM_G1CollectForAllocation operation.
594 // This function does everything necessary/possible to satisfy a
595 // failed allocation request (including collection, expansion, etc.)
596 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
598 // Attempting to expand the heap sufficiently
599 // to support an allocation of the given "word_size". If
600 // successful, perform the allocation and return the address of the
601 // allocated block, or else "NULL".
602 HeapWord* expand_and_allocate(size_t word_size);
604 // Process any reference objects discovered during
605 // an incremental evacuation pause.
606 void process_discovered_references();
608 // Enqueue any remaining discovered references
609 // after processing.
610 void enqueue_discovered_references();
612 public:
614 G1MonitoringSupport* g1mm() {
615 assert(_g1mm != NULL, "should have been initialized");
616 return _g1mm;
617 }
619 // Expand the garbage-first heap by at least the given size (in bytes!).
620 // Returns true if the heap was expanded by the requested amount;
621 // false otherwise.
622 // (Rounds up to a HeapRegion boundary.)
623 bool expand(size_t expand_bytes);
625 // Do anything common to GC's.
626 virtual void gc_prologue(bool full);
627 virtual void gc_epilogue(bool full);
629 // We register a region with the fast "in collection set" test. We
630 // simply set to true the array slot corresponding to this region.
631 void register_region_with_in_cset_fast_test(HeapRegion* r) {
632 assert(_in_cset_fast_test_base != NULL, "sanity");
633 assert(r->in_collection_set(), "invariant");
634 size_t index = r->hrs_index();
635 assert(index < _in_cset_fast_test_length, "invariant");
636 assert(!_in_cset_fast_test_base[index], "invariant");
637 _in_cset_fast_test_base[index] = true;
638 }
640 // This is a fast test on whether a reference points into the
641 // collection set or not. It does not assume that the reference
642 // points into the heap; if it doesn't, it will return false.
643 bool in_cset_fast_test(oop obj) {
644 assert(_in_cset_fast_test != NULL, "sanity");
645 if (_g1_committed.contains((HeapWord*) obj)) {
646 // no need to subtract the bottom of the heap from obj,
647 // _in_cset_fast_test is biased
648 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
649 bool ret = _in_cset_fast_test[index];
650 // let's make sure the result is consistent with what the slower
651 // test returns
652 assert( ret || !obj_in_cs(obj), "sanity");
653 assert(!ret || obj_in_cs(obj), "sanity");
654 return ret;
655 } else {
656 return false;
657 }
658 }
660 void clear_cset_fast_test() {
661 assert(_in_cset_fast_test_base != NULL, "sanity");
662 memset(_in_cset_fast_test_base, false,
663 _in_cset_fast_test_length * sizeof(bool));
664 }
666 // This is called at the end of either a concurrent cycle or a Full
667 // GC to update the number of full collections completed. Those two
668 // can happen in a nested fashion, i.e., we start a concurrent
669 // cycle, a Full GC happens half-way through it which ends first,
670 // and then the cycle notices that a Full GC happened and ends
671 // too. The concurrent parameter is a boolean to help us do a bit
672 // tighter consistency checking in the method. If concurrent is
673 // false, the caller is the inner caller in the nesting (i.e., the
674 // Full GC). If concurrent is true, the caller is the outer caller
675 // in this nesting (i.e., the concurrent cycle). Further nesting is
676 // not currently supported. The end of the this call also notifies
677 // the FullGCCount_lock in case a Java thread is waiting for a full
678 // GC to happen (e.g., it called System.gc() with
679 // +ExplicitGCInvokesConcurrent).
680 void increment_full_collections_completed(bool concurrent);
682 unsigned int full_collections_completed() {
683 return _full_collections_completed;
684 }
686 G1HRPrinter* hr_printer() { return &_hr_printer; }
688 protected:
690 // Shrink the garbage-first heap by at most the given size (in bytes!).
691 // (Rounds down to a HeapRegion boundary.)
692 virtual void shrink(size_t expand_bytes);
693 void shrink_helper(size_t expand_bytes);
695 #if TASKQUEUE_STATS
696 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
697 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
698 void reset_taskqueue_stats();
699 #endif // TASKQUEUE_STATS
701 // Schedule the VM operation that will do an evacuation pause to
702 // satisfy an allocation request of word_size. *succeeded will
703 // return whether the VM operation was successful (it did do an
704 // evacuation pause) or not (another thread beat us to it or the GC
705 // locker was active). Given that we should not be holding the
706 // Heap_lock when we enter this method, we will pass the
707 // gc_count_before (i.e., total_collections()) as a parameter since
708 // it has to be read while holding the Heap_lock. Currently, both
709 // methods that call do_collection_pause() release the Heap_lock
710 // before the call, so it's easy to read gc_count_before just before.
711 HeapWord* do_collection_pause(size_t word_size,
712 unsigned int gc_count_before,
713 bool* succeeded);
715 // The guts of the incremental collection pause, executed by the vm
716 // thread. It returns false if it is unable to do the collection due
717 // to the GC locker being active, true otherwise
718 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
720 // Actually do the work of evacuating the collection set.
721 void evacuate_collection_set();
723 // The g1 remembered set of the heap.
724 G1RemSet* _g1_rem_set;
725 // And it's mod ref barrier set, used to track updates for the above.
726 ModRefBarrierSet* _mr_bs;
728 // A set of cards that cover the objects for which the Rsets should be updated
729 // concurrently after the collection.
730 DirtyCardQueueSet _dirty_card_queue_set;
732 // The Heap Region Rem Set Iterator.
733 HeapRegionRemSetIterator** _rem_set_iterator;
735 // The closure used to refine a single card.
736 RefineCardTableEntryClosure* _refine_cte_cl;
738 // A function to check the consistency of dirty card logs.
739 void check_ct_logs_at_safepoint();
741 // A DirtyCardQueueSet that is used to hold cards that contain
742 // references into the current collection set. This is used to
743 // update the remembered sets of the regions in the collection
744 // set in the event of an evacuation failure.
745 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
747 // After a collection pause, make the regions in the CS into free
748 // regions.
749 void free_collection_set(HeapRegion* cs_head);
751 // Abandon the current collection set without recording policy
752 // statistics or updating free lists.
753 void abandon_collection_set(HeapRegion* cs_head);
755 // Applies "scan_non_heap_roots" to roots outside the heap,
756 // "scan_rs" to roots inside the heap (having done "set_region" to
757 // indicate the region in which the root resides), and does "scan_perm"
758 // (setting the generation to the perm generation.) If "scan_rs" is
759 // NULL, then this step is skipped. The "worker_i"
760 // param is for use with parallel roots processing, and should be
761 // the "i" of the calling parallel worker thread's work(i) function.
762 // In the sequential case this param will be ignored.
763 void g1_process_strong_roots(bool collecting_perm_gen,
764 SharedHeap::ScanningOption so,
765 OopClosure* scan_non_heap_roots,
766 OopsInHeapRegionClosure* scan_rs,
767 OopsInGenClosure* scan_perm,
768 int worker_i);
770 // Apply "blk" to all the weak roots of the system. These include
771 // JNI weak roots, the code cache, system dictionary, symbol table,
772 // string table, and referents of reachable weak refs.
773 void g1_process_weak_roots(OopClosure* root_closure,
774 OopClosure* non_root_closure);
776 // Frees a non-humongous region by initializing its contents and
777 // adding it to the free list that's passed as a parameter (this is
778 // usually a local list which will be appended to the master free
779 // list later). The used bytes of freed regions are accumulated in
780 // pre_used. If par is true, the region's RSet will not be freed
781 // up. The assumption is that this will be done later.
782 void free_region(HeapRegion* hr,
783 size_t* pre_used,
784 FreeRegionList* free_list,
785 bool par);
787 // Frees a humongous region by collapsing it into individual regions
788 // and calling free_region() for each of them. The freed regions
789 // will be added to the free list that's passed as a parameter (this
790 // is usually a local list which will be appended to the master free
791 // list later). The used bytes of freed regions are accumulated in
792 // pre_used. If par is true, the region's RSet will not be freed
793 // up. The assumption is that this will be done later.
794 void free_humongous_region(HeapRegion* hr,
795 size_t* pre_used,
796 FreeRegionList* free_list,
797 HumongousRegionSet* humongous_proxy_set,
798 bool par);
800 // Notifies all the necessary spaces that the committed space has
801 // been updated (either expanded or shrunk). It should be called
802 // after _g1_storage is updated.
803 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
805 // The concurrent marker (and the thread it runs in.)
806 ConcurrentMark* _cm;
807 ConcurrentMarkThread* _cmThread;
808 bool _mark_in_progress;
810 // The concurrent refiner.
811 ConcurrentG1Refine* _cg1r;
813 // The parallel task queues
814 RefToScanQueueSet *_task_queues;
816 // True iff a evacuation has failed in the current collection.
817 bool _evacuation_failed;
819 // Set the attribute indicating whether evacuation has failed in the
820 // current collection.
821 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
823 // Failed evacuations cause some logical from-space objects to have
824 // forwarding pointers to themselves. Reset them.
825 void remove_self_forwarding_pointers();
827 // When one is non-null, so is the other. Together, they each pair is
828 // an object with a preserved mark, and its mark value.
829 GrowableArray<oop>* _objs_with_preserved_marks;
830 GrowableArray<markOop>* _preserved_marks_of_objs;
832 // Preserve the mark of "obj", if necessary, in preparation for its mark
833 // word being overwritten with a self-forwarding-pointer.
834 void preserve_mark_if_necessary(oop obj, markOop m);
836 // The stack of evac-failure objects left to be scanned.
837 GrowableArray<oop>* _evac_failure_scan_stack;
838 // The closure to apply to evac-failure objects.
840 OopsInHeapRegionClosure* _evac_failure_closure;
841 // Set the field above.
842 void
843 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
844 _evac_failure_closure = evac_failure_closure;
845 }
847 // Push "obj" on the scan stack.
848 void push_on_evac_failure_scan_stack(oop obj);
849 // Process scan stack entries until the stack is empty.
850 void drain_evac_failure_scan_stack();
851 // True iff an invocation of "drain_scan_stack" is in progress; to
852 // prevent unnecessary recursion.
853 bool _drain_in_progress;
855 // Do any necessary initialization for evacuation-failure handling.
856 // "cl" is the closure that will be used to process evac-failure
857 // objects.
858 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
859 // Do any necessary cleanup for evacuation-failure handling data
860 // structures.
861 void finalize_for_evac_failure();
863 // An attempt to evacuate "obj" has failed; take necessary steps.
864 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj,
865 bool should_mark_root);
866 void handle_evacuation_failure_common(oop obj, markOop m);
868 // ("Weak") Reference processing support.
869 //
870 // G1 has 2 instances of the referece processor class. One
871 // (_ref_processor_cm) handles reference object discovery
872 // and subsequent processing during concurrent marking cycles.
873 //
874 // The other (_ref_processor_stw) handles reference object
875 // discovery and processing during full GCs and incremental
876 // evacuation pauses.
877 //
878 // During an incremental pause, reference discovery will be
879 // temporarily disabled for _ref_processor_cm and will be
880 // enabled for _ref_processor_stw. At the end of the evacuation
881 // pause references discovered by _ref_processor_stw will be
882 // processed and discovery will be disabled. The previous
883 // setting for reference object discovery for _ref_processor_cm
884 // will be re-instated.
885 //
886 // At the start of marking:
887 // * Discovery by the CM ref processor is verified to be inactive
888 // and it's discovered lists are empty.
889 // * Discovery by the CM ref processor is then enabled.
890 //
891 // At the end of marking:
892 // * Any references on the CM ref processor's discovered
893 // lists are processed (possibly MT).
894 //
895 // At the start of full GC we:
896 // * Disable discovery by the CM ref processor and
897 // empty CM ref processor's discovered lists
898 // (without processing any entries).
899 // * Verify that the STW ref processor is inactive and it's
900 // discovered lists are empty.
901 // * Temporarily set STW ref processor discovery as single threaded.
902 // * Temporarily clear the STW ref processor's _is_alive_non_header
903 // field.
904 // * Finally enable discovery by the STW ref processor.
905 //
906 // The STW ref processor is used to record any discovered
907 // references during the full GC.
908 //
909 // At the end of a full GC we:
910 // * Enqueue any reference objects discovered by the STW ref processor
911 // that have non-live referents. This has the side-effect of
912 // making the STW ref processor inactive by disabling discovery.
913 // * Verify that the CM ref processor is still inactive
914 // and no references have been placed on it's discovered
915 // lists (also checked as a precondition during initial marking).
917 // The (stw) reference processor...
918 ReferenceProcessor* _ref_processor_stw;
920 // During reference object discovery, the _is_alive_non_header
921 // closure (if non-null) is applied to the referent object to
922 // determine whether the referent is live. If so then the
923 // reference object does not need to be 'discovered' and can
924 // be treated as a regular oop. This has the benefit of reducing
925 // the number of 'discovered' reference objects that need to
926 // be processed.
927 //
928 // Instance of the is_alive closure for embedding into the
929 // STW reference processor as the _is_alive_non_header field.
930 // Supplying a value for the _is_alive_non_header field is
931 // optional but doing so prevents unnecessary additions to
932 // the discovered lists during reference discovery.
933 G1STWIsAliveClosure _is_alive_closure_stw;
935 // The (concurrent marking) reference processor...
936 ReferenceProcessor* _ref_processor_cm;
938 // Instance of the concurrent mark is_alive closure for embedding
939 // into the Concurrent Marking reference processor as the
940 // _is_alive_non_header field. Supplying a value for the
941 // _is_alive_non_header field is optional but doing so prevents
942 // unnecessary additions to the discovered lists during reference
943 // discovery.
944 G1CMIsAliveClosure _is_alive_closure_cm;
946 enum G1H_process_strong_roots_tasks {
947 G1H_PS_mark_stack_oops_do,
948 G1H_PS_refProcessor_oops_do,
949 // Leave this one last.
950 G1H_PS_NumElements
951 };
953 SubTasksDone* _process_strong_tasks;
955 volatile bool _free_regions_coming;
957 public:
959 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
961 void set_refine_cte_cl_concurrency(bool concurrent);
963 RefToScanQueue *task_queue(int i) const;
965 // A set of cards where updates happened during the GC
966 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
968 // A DirtyCardQueueSet that is used to hold cards that contain
969 // references into the current collection set. This is used to
970 // update the remembered sets of the regions in the collection
971 // set in the event of an evacuation failure.
972 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
973 { return _into_cset_dirty_card_queue_set; }
975 // Create a G1CollectedHeap with the specified policy.
976 // Must call the initialize method afterwards.
977 // May not return if something goes wrong.
978 G1CollectedHeap(G1CollectorPolicy* policy);
980 // Initialize the G1CollectedHeap to have the initial and
981 // maximum sizes, permanent generation, and remembered and barrier sets
982 // specified by the policy object.
983 jint initialize();
985 // Initialize weak reference processing.
986 virtual void ref_processing_init();
988 void set_par_threads(int t) {
989 SharedHeap::set_par_threads(t);
990 // Done in SharedHeap but oddly there are
991 // two _process_strong_tasks's in a G1CollectedHeap
992 // so do it here too.
993 _process_strong_tasks->set_n_threads(t);
994 }
996 // Set _n_par_threads according to a policy TBD.
997 void set_par_threads();
999 void set_n_termination(int t) {
1000 _process_strong_tasks->set_n_threads(t);
1001 }
1003 virtual CollectedHeap::Name kind() const {
1004 return CollectedHeap::G1CollectedHeap;
1005 }
1007 // The current policy object for the collector.
1008 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1010 // Adaptive size policy. No such thing for g1.
1011 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1013 // The rem set and barrier set.
1014 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1015 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1017 // The rem set iterator.
1018 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1019 return _rem_set_iterator[i];
1020 }
1022 HeapRegionRemSetIterator* rem_set_iterator() {
1023 return _rem_set_iterator[0];
1024 }
1026 unsigned get_gc_time_stamp() {
1027 return _gc_time_stamp;
1028 }
1030 void reset_gc_time_stamp() {
1031 _gc_time_stamp = 0;
1032 OrderAccess::fence();
1033 }
1035 void increment_gc_time_stamp() {
1036 ++_gc_time_stamp;
1037 OrderAccess::fence();
1038 }
1040 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1041 DirtyCardQueue* into_cset_dcq,
1042 bool concurrent, int worker_i);
1044 // The shared block offset table array.
1045 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1047 // Reference Processing accessors
1049 // The STW reference processor....
1050 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1052 // The Concurent Marking reference processor...
1053 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1055 virtual size_t capacity() const;
1056 virtual size_t used() const;
1057 // This should be called when we're not holding the heap lock. The
1058 // result might be a bit inaccurate.
1059 size_t used_unlocked() const;
1060 size_t recalculate_used() const;
1062 // These virtual functions do the actual allocation.
1063 // Some heaps may offer a contiguous region for shared non-blocking
1064 // allocation, via inlined code (by exporting the address of the top and
1065 // end fields defining the extent of the contiguous allocation region.)
1066 // But G1CollectedHeap doesn't yet support this.
1068 // Return an estimate of the maximum allocation that could be performed
1069 // without triggering any collection or expansion activity. In a
1070 // generational collector, for example, this is probably the largest
1071 // allocation that could be supported (without expansion) in the youngest
1072 // generation. It is "unsafe" because no locks are taken; the result
1073 // should be treated as an approximation, not a guarantee, for use in
1074 // heuristic resizing decisions.
1075 virtual size_t unsafe_max_alloc();
1077 virtual bool is_maximal_no_gc() const {
1078 return _g1_storage.uncommitted_size() == 0;
1079 }
1081 // The total number of regions in the heap.
1082 size_t n_regions() { return _hrs.length(); }
1084 // The max number of regions in the heap.
1085 size_t max_regions() { return _hrs.max_length(); }
1087 // The number of regions that are completely free.
1088 size_t free_regions() { return _free_list.length(); }
1090 // The number of regions that are not completely free.
1091 size_t used_regions() { return n_regions() - free_regions(); }
1093 // The number of regions available for "regular" expansion.
1094 size_t expansion_regions() { return _expansion_regions; }
1096 // Factory method for HeapRegion instances. It will return NULL if
1097 // the allocation fails.
1098 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1100 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1101 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1102 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1103 void verify_dirty_young_regions() PRODUCT_RETURN;
1105 // verify_region_sets() performs verification over the region
1106 // lists. It will be compiled in the product code to be used when
1107 // necessary (i.e., during heap verification).
1108 void verify_region_sets();
1110 // verify_region_sets_optional() is planted in the code for
1111 // list verification in non-product builds (and it can be enabled in
1112 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1113 #if HEAP_REGION_SET_FORCE_VERIFY
1114 void verify_region_sets_optional() {
1115 verify_region_sets();
1116 }
1117 #else // HEAP_REGION_SET_FORCE_VERIFY
1118 void verify_region_sets_optional() { }
1119 #endif // HEAP_REGION_SET_FORCE_VERIFY
1121 #ifdef ASSERT
1122 bool is_on_master_free_list(HeapRegion* hr) {
1123 return hr->containing_set() == &_free_list;
1124 }
1126 bool is_in_humongous_set(HeapRegion* hr) {
1127 return hr->containing_set() == &_humongous_set;
1128 }
1129 #endif // ASSERT
1131 // Wrapper for the region list operations that can be called from
1132 // methods outside this class.
1134 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1135 _secondary_free_list.add_as_tail(list);
1136 }
1138 void append_secondary_free_list() {
1139 _free_list.add_as_head(&_secondary_free_list);
1140 }
1142 void append_secondary_free_list_if_not_empty_with_lock() {
1143 // If the secondary free list looks empty there's no reason to
1144 // take the lock and then try to append it.
1145 if (!_secondary_free_list.is_empty()) {
1146 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1147 append_secondary_free_list();
1148 }
1149 }
1151 void old_set_remove(HeapRegion* hr) {
1152 _old_set.remove(hr);
1153 }
1155 void set_free_regions_coming();
1156 void reset_free_regions_coming();
1157 bool free_regions_coming() { return _free_regions_coming; }
1158 void wait_while_free_regions_coming();
1160 // Perform a collection of the heap; intended for use in implementing
1161 // "System.gc". This probably implies as full a collection as the
1162 // "CollectedHeap" supports.
1163 virtual void collect(GCCause::Cause cause);
1165 // The same as above but assume that the caller holds the Heap_lock.
1166 void collect_locked(GCCause::Cause cause);
1168 // This interface assumes that it's being called by the
1169 // vm thread. It collects the heap assuming that the
1170 // heap lock is already held and that we are executing in
1171 // the context of the vm thread.
1172 virtual void collect_as_vm_thread(GCCause::Cause cause);
1174 // True iff a evacuation has failed in the most-recent collection.
1175 bool evacuation_failed() { return _evacuation_failed; }
1177 // It will free a region if it has allocated objects in it that are
1178 // all dead. It calls either free_region() or
1179 // free_humongous_region() depending on the type of the region that
1180 // is passed to it.
1181 void free_region_if_empty(HeapRegion* hr,
1182 size_t* pre_used,
1183 FreeRegionList* free_list,
1184 OldRegionSet* old_proxy_set,
1185 HumongousRegionSet* humongous_proxy_set,
1186 HRRSCleanupTask* hrrs_cleanup_task,
1187 bool par);
1189 // It appends the free list to the master free list and updates the
1190 // master humongous list according to the contents of the proxy
1191 // list. It also adjusts the total used bytes according to pre_used
1192 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1193 void update_sets_after_freeing_regions(size_t pre_used,
1194 FreeRegionList* free_list,
1195 OldRegionSet* old_proxy_set,
1196 HumongousRegionSet* humongous_proxy_set,
1197 bool par);
1199 // Returns "TRUE" iff "p" points into the allocated area of the heap.
1200 virtual bool is_in(const void* p) const;
1202 // Return "TRUE" iff the given object address is within the collection
1203 // set.
1204 inline bool obj_in_cs(oop obj);
1206 // Return "TRUE" iff the given object address is in the reserved
1207 // region of g1 (excluding the permanent generation).
1208 bool is_in_g1_reserved(const void* p) const {
1209 return _g1_reserved.contains(p);
1210 }
1212 // Returns a MemRegion that corresponds to the space that has been
1213 // reserved for the heap
1214 MemRegion g1_reserved() {
1215 return _g1_reserved;
1216 }
1218 // Returns a MemRegion that corresponds to the space that has been
1219 // committed in the heap
1220 MemRegion g1_committed() {
1221 return _g1_committed;
1222 }
1224 virtual bool is_in_closed_subset(const void* p) const;
1226 // This resets the card table to all zeros. It is used after
1227 // a collection pause which used the card table to claim cards.
1228 void cleanUpCardTable();
1230 // Iteration functions.
1232 // Iterate over all the ref-containing fields of all objects, calling
1233 // "cl.do_oop" on each.
1234 virtual void oop_iterate(OopClosure* cl) {
1235 oop_iterate(cl, true);
1236 }
1237 void oop_iterate(OopClosure* cl, bool do_perm);
1239 // Same as above, restricted to a memory region.
1240 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1241 oop_iterate(mr, cl, true);
1242 }
1243 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1245 // Iterate over all objects, calling "cl.do_object" on each.
1246 virtual void object_iterate(ObjectClosure* cl) {
1247 object_iterate(cl, true);
1248 }
1249 virtual void safe_object_iterate(ObjectClosure* cl) {
1250 object_iterate(cl, true);
1251 }
1252 void object_iterate(ObjectClosure* cl, bool do_perm);
1254 // Iterate over all objects allocated since the last collection, calling
1255 // "cl.do_object" on each. The heap must have been initialized properly
1256 // to support this function, or else this call will fail.
1257 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1259 // Iterate over all spaces in use in the heap, in ascending address order.
1260 virtual void space_iterate(SpaceClosure* cl);
1262 // Iterate over heap regions, in address order, terminating the
1263 // iteration early if the "doHeapRegion" method returns "true".
1264 void heap_region_iterate(HeapRegionClosure* blk) const;
1266 // Iterate over heap regions starting with r (or the first region if "r"
1267 // is NULL), in address order, terminating early if the "doHeapRegion"
1268 // method returns "true".
1269 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1271 // Return the region with the given index. It assumes the index is valid.
1272 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1274 // Divide the heap region sequence into "chunks" of some size (the number
1275 // of regions divided by the number of parallel threads times some
1276 // overpartition factor, currently 4). Assumes that this will be called
1277 // in parallel by ParallelGCThreads worker threads with discinct worker
1278 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1279 // calls will use the same "claim_value", and that that claim value is
1280 // different from the claim_value of any heap region before the start of
1281 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1282 // attempting to claim the first region in each chunk, and, if
1283 // successful, applying the closure to each region in the chunk (and
1284 // setting the claim value of the second and subsequent regions of the
1285 // chunk.) For now requires that "doHeapRegion" always returns "false",
1286 // i.e., that a closure never attempt to abort a traversal.
1287 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1288 int worker,
1289 int no_of_par_workers,
1290 jint claim_value);
1292 // It resets all the region claim values to the default.
1293 void reset_heap_region_claim_values();
1295 #ifdef ASSERT
1296 bool check_heap_region_claim_values(jint claim_value);
1298 // Same as the routine above but only checks regions in the
1299 // current collection set.
1300 bool check_cset_heap_region_claim_values(jint claim_value);
1301 #endif // ASSERT
1303 // Given the id of a worker, calculate a suitable
1304 // starting region for iterating over the current
1305 // collection set.
1306 HeapRegion* start_cset_region_for_worker(int worker_i);
1308 // Iterate over the regions (if any) in the current collection set.
1309 void collection_set_iterate(HeapRegionClosure* blk);
1311 // As above but starting from region r
1312 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1314 // Returns the first (lowest address) compactible space in the heap.
1315 virtual CompactibleSpace* first_compactible_space();
1317 // A CollectedHeap will contain some number of spaces. This finds the
1318 // space containing a given address, or else returns NULL.
1319 virtual Space* space_containing(const void* addr) const;
1321 // A G1CollectedHeap will contain some number of heap regions. This
1322 // finds the region containing a given address, or else returns NULL.
1323 template <class T>
1324 inline HeapRegion* heap_region_containing(const T addr) const;
1326 // Like the above, but requires "addr" to be in the heap (to avoid a
1327 // null-check), and unlike the above, may return an continuing humongous
1328 // region.
1329 template <class T>
1330 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1332 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1333 // each address in the (reserved) heap is a member of exactly
1334 // one block. The defining characteristic of a block is that it is
1335 // possible to find its size, and thus to progress forward to the next
1336 // block. (Blocks may be of different sizes.) Thus, blocks may
1337 // represent Java objects, or they might be free blocks in a
1338 // free-list-based heap (or subheap), as long as the two kinds are
1339 // distinguishable and the size of each is determinable.
1341 // Returns the address of the start of the "block" that contains the
1342 // address "addr". We say "blocks" instead of "object" since some heaps
1343 // may not pack objects densely; a chunk may either be an object or a
1344 // non-object.
1345 virtual HeapWord* block_start(const void* addr) const;
1347 // Requires "addr" to be the start of a chunk, and returns its size.
1348 // "addr + size" is required to be the start of a new chunk, or the end
1349 // of the active area of the heap.
1350 virtual size_t block_size(const HeapWord* addr) const;
1352 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1353 // the block is an object.
1354 virtual bool block_is_obj(const HeapWord* addr) const;
1356 // Does this heap support heap inspection? (+PrintClassHistogram)
1357 virtual bool supports_heap_inspection() const { return true; }
1359 // Section on thread-local allocation buffers (TLABs)
1360 // See CollectedHeap for semantics.
1362 virtual bool supports_tlab_allocation() const;
1363 virtual size_t tlab_capacity(Thread* thr) const;
1364 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1366 // Can a compiler initialize a new object without store barriers?
1367 // This permission only extends from the creation of a new object
1368 // via a TLAB up to the first subsequent safepoint. If such permission
1369 // is granted for this heap type, the compiler promises to call
1370 // defer_store_barrier() below on any slow path allocation of
1371 // a new object for which such initializing store barriers will
1372 // have been elided. G1, like CMS, allows this, but should be
1373 // ready to provide a compensating write barrier as necessary
1374 // if that storage came out of a non-young region. The efficiency
1375 // of this implementation depends crucially on being able to
1376 // answer very efficiently in constant time whether a piece of
1377 // storage in the heap comes from a young region or not.
1378 // See ReduceInitialCardMarks.
1379 virtual bool can_elide_tlab_store_barriers() const {
1380 return true;
1381 }
1383 virtual bool card_mark_must_follow_store() const {
1384 return true;
1385 }
1387 bool is_in_young(const oop obj) {
1388 HeapRegion* hr = heap_region_containing(obj);
1389 return hr != NULL && hr->is_young();
1390 }
1392 #ifdef ASSERT
1393 virtual bool is_in_partial_collection(const void* p);
1394 #endif
1396 virtual bool is_scavengable(const void* addr);
1398 // We don't need barriers for initializing stores to objects
1399 // in the young gen: for the SATB pre-barrier, there is no
1400 // pre-value that needs to be remembered; for the remembered-set
1401 // update logging post-barrier, we don't maintain remembered set
1402 // information for young gen objects.
1403 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1404 return is_in_young(new_obj);
1405 }
1407 // Can a compiler elide a store barrier when it writes
1408 // a permanent oop into the heap? Applies when the compiler
1409 // is storing x to the heap, where x->is_perm() is true.
1410 virtual bool can_elide_permanent_oop_store_barriers() const {
1411 // At least until perm gen collection is also G1-ified, at
1412 // which point this should return false.
1413 return true;
1414 }
1416 // Returns "true" iff the given word_size is "very large".
1417 static bool isHumongous(size_t word_size) {
1418 // Note this has to be strictly greater-than as the TLABs
1419 // are capped at the humongous thresold and we want to
1420 // ensure that we don't try to allocate a TLAB as
1421 // humongous and that we don't allocate a humongous
1422 // object in a TLAB.
1423 return word_size > _humongous_object_threshold_in_words;
1424 }
1426 // Update mod union table with the set of dirty cards.
1427 void updateModUnion();
1429 // Set the mod union bits corresponding to the given memRegion. Note
1430 // that this is always a safe operation, since it doesn't clear any
1431 // bits.
1432 void markModUnionRange(MemRegion mr);
1434 // Records the fact that a marking phase is no longer in progress.
1435 void set_marking_complete() {
1436 _mark_in_progress = false;
1437 }
1438 void set_marking_started() {
1439 _mark_in_progress = true;
1440 }
1441 bool mark_in_progress() {
1442 return _mark_in_progress;
1443 }
1445 // Print the maximum heap capacity.
1446 virtual size_t max_capacity() const;
1448 virtual jlong millis_since_last_gc();
1450 // Perform any cleanup actions necessary before allowing a verification.
1451 virtual void prepare_for_verify();
1453 // Perform verification.
1455 // vo == UsePrevMarking -> use "prev" marking information,
1456 // vo == UseNextMarking -> use "next" marking information
1457 // vo == UseMarkWord -> use the mark word in the object header
1458 //
1459 // NOTE: Only the "prev" marking information is guaranteed to be
1460 // consistent most of the time, so most calls to this should use
1461 // vo == UsePrevMarking.
1462 // Currently, there is only one case where this is called with
1463 // vo == UseNextMarking, which is to verify the "next" marking
1464 // information at the end of remark.
1465 // Currently there is only one place where this is called with
1466 // vo == UseMarkWord, which is to verify the marking during a
1467 // full GC.
1468 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1470 // Override; it uses the "prev" marking information
1471 virtual void verify(bool allow_dirty, bool silent);
1472 virtual void print_on(outputStream* st) const;
1473 virtual void print_extended_on(outputStream* st) const;
1475 virtual void print_gc_threads_on(outputStream* st) const;
1476 virtual void gc_threads_do(ThreadClosure* tc) const;
1478 // Override
1479 void print_tracing_info() const;
1481 // The following two methods are helpful for debugging RSet issues.
1482 void print_cset_rsets() PRODUCT_RETURN;
1483 void print_all_rsets() PRODUCT_RETURN;
1485 // Convenience function to be used in situations where the heap type can be
1486 // asserted to be this type.
1487 static G1CollectedHeap* heap();
1489 void set_region_short_lived_locked(HeapRegion* hr);
1490 // add appropriate methods for any other surv rate groups
1492 YoungList* young_list() { return _young_list; }
1494 // debugging
1495 bool check_young_list_well_formed() {
1496 return _young_list->check_list_well_formed();
1497 }
1499 bool check_young_list_empty(bool check_heap,
1500 bool check_sample = true);
1502 // *** Stuff related to concurrent marking. It's not clear to me that so
1503 // many of these need to be public.
1505 // The functions below are helper functions that a subclass of
1506 // "CollectedHeap" can use in the implementation of its virtual
1507 // functions.
1508 // This performs a concurrent marking of the live objects in a
1509 // bitmap off to the side.
1510 void doConcurrentMark();
1512 bool isMarkedPrev(oop obj) const;
1513 bool isMarkedNext(oop obj) const;
1515 // vo == UsePrevMarking -> use "prev" marking information,
1516 // vo == UseNextMarking -> use "next" marking information,
1517 // vo == UseMarkWord -> use mark word from object header
1518 bool is_obj_dead_cond(const oop obj,
1519 const HeapRegion* hr,
1520 const VerifyOption vo) const {
1522 switch (vo) {
1523 case VerifyOption_G1UsePrevMarking:
1524 return is_obj_dead(obj, hr);
1525 case VerifyOption_G1UseNextMarking:
1526 return is_obj_ill(obj, hr);
1527 default:
1528 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1529 return !obj->is_gc_marked();
1530 }
1531 }
1533 // Determine if an object is dead, given the object and also
1534 // the region to which the object belongs. An object is dead
1535 // iff a) it was not allocated since the last mark and b) it
1536 // is not marked.
1538 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1539 return
1540 !hr->obj_allocated_since_prev_marking(obj) &&
1541 !isMarkedPrev(obj);
1542 }
1544 // This is used when copying an object to survivor space.
1545 // If the object is marked live, then we mark the copy live.
1546 // If the object is allocated since the start of this mark
1547 // cycle, then we mark the copy live.
1548 // If the object has been around since the previous mark
1549 // phase, and hasn't been marked yet during this phase,
1550 // then we don't mark it, we just wait for the
1551 // current marking cycle to get to it.
1553 // This function returns true when an object has been
1554 // around since the previous marking and hasn't yet
1555 // been marked during this marking.
1557 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1558 return
1559 !hr->obj_allocated_since_next_marking(obj) &&
1560 !isMarkedNext(obj);
1561 }
1563 // Determine if an object is dead, given only the object itself.
1564 // This will find the region to which the object belongs and
1565 // then call the region version of the same function.
1567 // Added if it is in permanent gen it isn't dead.
1568 // Added if it is NULL it isn't dead.
1570 // vo == UsePrevMarking -> use "prev" marking information,
1571 // vo == UseNextMarking -> use "next" marking information,
1572 // vo == UseMarkWord -> use mark word from object header
1573 bool is_obj_dead_cond(const oop obj,
1574 const VerifyOption vo) const {
1576 switch (vo) {
1577 case VerifyOption_G1UsePrevMarking:
1578 return is_obj_dead(obj);
1579 case VerifyOption_G1UseNextMarking:
1580 return is_obj_ill(obj);
1581 default:
1582 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1583 return !obj->is_gc_marked();
1584 }
1585 }
1587 bool is_obj_dead(const oop obj) const {
1588 const HeapRegion* hr = heap_region_containing(obj);
1589 if (hr == NULL) {
1590 if (Universe::heap()->is_in_permanent(obj))
1591 return false;
1592 else if (obj == NULL) return false;
1593 else return true;
1594 }
1595 else return is_obj_dead(obj, hr);
1596 }
1598 bool is_obj_ill(const oop obj) const {
1599 const HeapRegion* hr = heap_region_containing(obj);
1600 if (hr == NULL) {
1601 if (Universe::heap()->is_in_permanent(obj))
1602 return false;
1603 else if (obj == NULL) return false;
1604 else return true;
1605 }
1606 else return is_obj_ill(obj, hr);
1607 }
1609 // The following is just to alert the verification code
1610 // that a full collection has occurred and that the
1611 // remembered sets are no longer up to date.
1612 bool _full_collection;
1613 void set_full_collection() { _full_collection = true;}
1614 void clear_full_collection() {_full_collection = false;}
1615 bool full_collection() {return _full_collection;}
1617 ConcurrentMark* concurrent_mark() const { return _cm; }
1618 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1620 // The dirty cards region list is used to record a subset of regions
1621 // whose cards need clearing. The list if populated during the
1622 // remembered set scanning and drained during the card table
1623 // cleanup. Although the methods are reentrant, population/draining
1624 // phases must not overlap. For synchronization purposes the last
1625 // element on the list points to itself.
1626 HeapRegion* _dirty_cards_region_list;
1627 void push_dirty_cards_region(HeapRegion* hr);
1628 HeapRegion* pop_dirty_cards_region();
1630 public:
1631 void stop_conc_gc_threads();
1633 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1634 void check_if_region_is_too_expensive(double predicted_time_ms);
1635 size_t pending_card_num();
1636 size_t max_pending_card_num();
1637 size_t cards_scanned();
1639 protected:
1640 size_t _max_heap_capacity;
1641 };
1643 #define use_local_bitmaps 1
1644 #define verify_local_bitmaps 0
1645 #define oop_buffer_length 256
1647 #ifndef PRODUCT
1648 class GCLabBitMap;
1649 class GCLabBitMapClosure: public BitMapClosure {
1650 private:
1651 ConcurrentMark* _cm;
1652 GCLabBitMap* _bitmap;
1654 public:
1655 GCLabBitMapClosure(ConcurrentMark* cm,
1656 GCLabBitMap* bitmap) {
1657 _cm = cm;
1658 _bitmap = bitmap;
1659 }
1661 virtual bool do_bit(size_t offset);
1662 };
1663 #endif // !PRODUCT
1665 class GCLabBitMap: public BitMap {
1666 private:
1667 ConcurrentMark* _cm;
1669 int _shifter;
1670 size_t _bitmap_word_covers_words;
1672 // beginning of the heap
1673 HeapWord* _heap_start;
1675 // this is the actual start of the GCLab
1676 HeapWord* _real_start_word;
1678 // this is the actual end of the GCLab
1679 HeapWord* _real_end_word;
1681 // this is the first word, possibly located before the actual start
1682 // of the GCLab, that corresponds to the first bit of the bitmap
1683 HeapWord* _start_word;
1685 // size of a GCLab in words
1686 size_t _gclab_word_size;
1688 static int shifter() {
1689 return MinObjAlignment - 1;
1690 }
1692 // how many heap words does a single bitmap word corresponds to?
1693 static size_t bitmap_word_covers_words() {
1694 return BitsPerWord << shifter();
1695 }
1697 size_t gclab_word_size() const {
1698 return _gclab_word_size;
1699 }
1701 // Calculates actual GCLab size in words
1702 size_t gclab_real_word_size() const {
1703 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1704 / BitsPerWord;
1705 }
1707 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1708 size_t bits_in_bitmap = gclab_word_size >> shifter();
1709 // We are going to ensure that the beginning of a word in this
1710 // bitmap also corresponds to the beginning of a word in the
1711 // global marking bitmap. To handle the case where a GCLab
1712 // starts from the middle of the bitmap, we need to add enough
1713 // space (i.e. up to a bitmap word) to ensure that we have
1714 // enough bits in the bitmap.
1715 return bits_in_bitmap + BitsPerWord - 1;
1716 }
1717 public:
1718 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1719 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1720 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1721 _shifter(shifter()),
1722 _bitmap_word_covers_words(bitmap_word_covers_words()),
1723 _heap_start(heap_start),
1724 _gclab_word_size(gclab_word_size),
1725 _real_start_word(NULL),
1726 _real_end_word(NULL),
1727 _start_word(NULL)
1728 {
1729 guarantee( size_in_words() >= bitmap_size_in_words(),
1730 "just making sure");
1731 }
1733 inline unsigned heapWordToOffset(HeapWord* addr) {
1734 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1735 assert(offset < size(), "offset should be within bounds");
1736 return offset;
1737 }
1739 inline HeapWord* offsetToHeapWord(size_t offset) {
1740 HeapWord* addr = _start_word + (offset << _shifter);
1741 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1742 return addr;
1743 }
1745 bool fields_well_formed() {
1746 bool ret1 = (_real_start_word == NULL) &&
1747 (_real_end_word == NULL) &&
1748 (_start_word == NULL);
1749 if (ret1)
1750 return true;
1752 bool ret2 = _real_start_word >= _start_word &&
1753 _start_word < _real_end_word &&
1754 (_real_start_word + _gclab_word_size) == _real_end_word &&
1755 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1756 > _real_end_word;
1757 return ret2;
1758 }
1760 inline bool mark(HeapWord* addr) {
1761 guarantee(use_local_bitmaps, "invariant");
1762 assert(fields_well_formed(), "invariant");
1764 if (addr >= _real_start_word && addr < _real_end_word) {
1765 assert(!isMarked(addr), "should not have already been marked");
1767 // first mark it on the bitmap
1768 at_put(heapWordToOffset(addr), true);
1770 return true;
1771 } else {
1772 return false;
1773 }
1774 }
1776 inline bool isMarked(HeapWord* addr) {
1777 guarantee(use_local_bitmaps, "invariant");
1778 assert(fields_well_formed(), "invariant");
1780 return at(heapWordToOffset(addr));
1781 }
1783 void set_buffer(HeapWord* start) {
1784 guarantee(use_local_bitmaps, "invariant");
1785 clear();
1787 assert(start != NULL, "invariant");
1788 _real_start_word = start;
1789 _real_end_word = start + _gclab_word_size;
1791 size_t diff =
1792 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1793 _start_word = start - diff;
1795 assert(fields_well_formed(), "invariant");
1796 }
1798 #ifndef PRODUCT
1799 void verify() {
1800 // verify that the marks have been propagated
1801 GCLabBitMapClosure cl(_cm, this);
1802 iterate(&cl);
1803 }
1804 #endif // PRODUCT
1806 void retire() {
1807 guarantee(use_local_bitmaps, "invariant");
1808 assert(fields_well_formed(), "invariant");
1810 if (_start_word != NULL) {
1811 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1813 // this means that the bitmap was set up for the GCLab
1814 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1816 mark_bitmap->mostly_disjoint_range_union(this,
1817 0, // always start from the start of the bitmap
1818 _start_word,
1819 gclab_real_word_size());
1820 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1822 #ifndef PRODUCT
1823 if (use_local_bitmaps && verify_local_bitmaps)
1824 verify();
1825 #endif // PRODUCT
1826 } else {
1827 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1828 }
1829 }
1831 size_t bitmap_size_in_words() const {
1832 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1833 }
1835 };
1837 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1838 private:
1839 bool _retired;
1840 bool _should_mark_objects;
1841 GCLabBitMap _bitmap;
1843 public:
1844 G1ParGCAllocBuffer(size_t gclab_word_size);
1846 inline bool mark(HeapWord* addr) {
1847 guarantee(use_local_bitmaps, "invariant");
1848 assert(_should_mark_objects, "invariant");
1849 return _bitmap.mark(addr);
1850 }
1852 inline void set_buf(HeapWord* buf) {
1853 if (use_local_bitmaps && _should_mark_objects) {
1854 _bitmap.set_buffer(buf);
1855 }
1856 ParGCAllocBuffer::set_buf(buf);
1857 _retired = false;
1858 }
1860 inline void retire(bool end_of_gc, bool retain) {
1861 if (_retired)
1862 return;
1863 if (use_local_bitmaps && _should_mark_objects) {
1864 _bitmap.retire();
1865 }
1866 ParGCAllocBuffer::retire(end_of_gc, retain);
1867 _retired = true;
1868 }
1869 };
1871 class G1ParScanThreadState : public StackObj {
1872 protected:
1873 G1CollectedHeap* _g1h;
1874 RefToScanQueue* _refs;
1875 DirtyCardQueue _dcq;
1876 CardTableModRefBS* _ct_bs;
1877 G1RemSet* _g1_rem;
1879 G1ParGCAllocBuffer _surviving_alloc_buffer;
1880 G1ParGCAllocBuffer _tenured_alloc_buffer;
1881 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1882 ageTable _age_table;
1884 size_t _alloc_buffer_waste;
1885 size_t _undo_waste;
1887 OopsInHeapRegionClosure* _evac_failure_cl;
1888 G1ParScanHeapEvacClosure* _evac_cl;
1889 G1ParScanPartialArrayClosure* _partial_scan_cl;
1891 int _hash_seed;
1892 int _queue_num;
1894 size_t _term_attempts;
1896 double _start;
1897 double _start_strong_roots;
1898 double _strong_roots_time;
1899 double _start_term;
1900 double _term_time;
1902 // Map from young-age-index (0 == not young, 1 is youngest) to
1903 // surviving words. base is what we get back from the malloc call
1904 size_t* _surviving_young_words_base;
1905 // this points into the array, as we use the first few entries for padding
1906 size_t* _surviving_young_words;
1908 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1910 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1912 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1914 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1915 CardTableModRefBS* ctbs() { return _ct_bs; }
1917 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1918 if (!from->is_survivor()) {
1919 _g1_rem->par_write_ref(from, p, tid);
1920 }
1921 }
1923 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1924 // If the new value of the field points to the same region or
1925 // is the to-space, we don't need to include it in the Rset updates.
1926 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1927 size_t card_index = ctbs()->index_for(p);
1928 // If the card hasn't been added to the buffer, do it.
1929 if (ctbs()->mark_card_deferred(card_index)) {
1930 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1931 }
1932 }
1933 }
1935 public:
1936 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
1938 ~G1ParScanThreadState() {
1939 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1940 }
1942 RefToScanQueue* refs() { return _refs; }
1943 ageTable* age_table() { return &_age_table; }
1945 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1946 return _alloc_buffers[purpose];
1947 }
1949 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1950 size_t undo_waste() const { return _undo_waste; }
1952 #ifdef ASSERT
1953 bool verify_ref(narrowOop* ref) const;
1954 bool verify_ref(oop* ref) const;
1955 bool verify_task(StarTask ref) const;
1956 #endif // ASSERT
1958 template <class T> void push_on_queue(T* ref) {
1959 assert(verify_ref(ref), "sanity");
1960 refs()->push(ref);
1961 }
1963 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1964 if (G1DeferredRSUpdate) {
1965 deferred_rs_update(from, p, tid);
1966 } else {
1967 immediate_rs_update(from, p, tid);
1968 }
1969 }
1971 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1973 HeapWord* obj = NULL;
1974 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1975 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1976 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1977 assert(gclab_word_size == alloc_buf->word_sz(),
1978 "dynamic resizing is not supported");
1979 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
1980 alloc_buf->retire(false, false);
1982 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
1983 if (buf == NULL) return NULL; // Let caller handle allocation failure.
1984 // Otherwise.
1985 alloc_buf->set_buf(buf);
1987 obj = alloc_buf->allocate(word_sz);
1988 assert(obj != NULL, "buffer was definitely big enough...");
1989 } else {
1990 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
1991 }
1992 return obj;
1993 }
1995 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
1996 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
1997 if (obj != NULL) return obj;
1998 return allocate_slow(purpose, word_sz);
1999 }
2001 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
2002 if (alloc_buffer(purpose)->contains(obj)) {
2003 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2004 "should contain whole object");
2005 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2006 } else {
2007 CollectedHeap::fill_with_object(obj, word_sz);
2008 add_to_undo_waste(word_sz);
2009 }
2010 }
2012 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2013 _evac_failure_cl = evac_failure_cl;
2014 }
2015 OopsInHeapRegionClosure* evac_failure_closure() {
2016 return _evac_failure_cl;
2017 }
2019 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2020 _evac_cl = evac_cl;
2021 }
2023 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2024 _partial_scan_cl = partial_scan_cl;
2025 }
2027 int* hash_seed() { return &_hash_seed; }
2028 int queue_num() { return _queue_num; }
2030 size_t term_attempts() const { return _term_attempts; }
2031 void note_term_attempt() { _term_attempts++; }
2033 void start_strong_roots() {
2034 _start_strong_roots = os::elapsedTime();
2035 }
2036 void end_strong_roots() {
2037 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2038 }
2039 double strong_roots_time() const { return _strong_roots_time; }
2041 void start_term_time() {
2042 note_term_attempt();
2043 _start_term = os::elapsedTime();
2044 }
2045 void end_term_time() {
2046 _term_time += (os::elapsedTime() - _start_term);
2047 }
2048 double term_time() const { return _term_time; }
2050 double elapsed_time() const {
2051 return os::elapsedTime() - _start;
2052 }
2054 static void
2055 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2056 void
2057 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2059 size_t* surviving_young_words() {
2060 // We add on to hide entry 0 which accumulates surviving words for
2061 // age -1 regions (i.e. non-young ones)
2062 return _surviving_young_words;
2063 }
2065 void retire_alloc_buffers() {
2066 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2067 size_t waste = _alloc_buffers[ap]->words_remaining();
2068 add_to_alloc_buffer_waste(waste);
2069 _alloc_buffers[ap]->retire(true, false);
2070 }
2071 }
2073 template <class T> void deal_with_reference(T* ref_to_scan) {
2074 if (has_partial_array_mask(ref_to_scan)) {
2075 _partial_scan_cl->do_oop_nv(ref_to_scan);
2076 } else {
2077 // Note: we can use "raw" versions of "region_containing" because
2078 // "obj_to_scan" is definitely in the heap, and is not in a
2079 // humongous region.
2080 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2081 _evac_cl->set_region(r);
2082 _evac_cl->do_oop_nv(ref_to_scan);
2083 }
2084 }
2086 void deal_with_reference(StarTask ref) {
2087 assert(verify_task(ref), "sanity");
2088 if (ref.is_narrow()) {
2089 deal_with_reference((narrowOop*)ref);
2090 } else {
2091 deal_with_reference((oop*)ref);
2092 }
2093 }
2095 public:
2096 void trim_queue();
2097 };
2099 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP