1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP
27
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"
40
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.
45
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;
64
65 typedef OverflowTaskQueue<StarTask> RefToScanQueue;
66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
67
68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
70
71 enum GCAllocPurpose {
72 GCAllocForTenured,
73 GCAllocForSurvived,
74 GCAllocPurposeCount
75 };
76
77 class YoungList : public CHeapObj {
78 private:
79 G1CollectedHeap* _g1h;
80
81 HeapRegion* _head;
82
83 HeapRegion* _survivor_head;
84 HeapRegion* _survivor_tail;
85
86 HeapRegion* _curr;
87
88 size_t _length;
89 size_t _survivor_length;
90
91 size_t _last_sampled_rs_lengths;
92 size_t _sampled_rs_lengths;
93
94 void empty_list(HeapRegion* list);
95
96 public:
97 YoungList(G1CollectedHeap* g1h);
98
99 void push_region(HeapRegion* hr);
100 void add_survivor_region(HeapRegion* hr);
101
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; }
106
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 }
119
120 void rs_length_sampling_init();
121 bool rs_length_sampling_more();
122 void rs_length_sampling_next();
123
124 void reset_sampled_info() {
125 _last_sampled_rs_lengths = 0;
126 }
127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
128
129 // for development purposes
130 void reset_auxilary_lists();
131 void clear() { _head = NULL; _length = 0; }
132
133 void clear_survivors() {
134 _survivor_head = NULL;
135 _survivor_tail = NULL;
136 _survivor_length = 0;
137 }
138
139 HeapRegion* first_region() { return _head; }
140 HeapRegion* first_survivor_region() { return _survivor_head; }
141 HeapRegion* last_survivor_region() { return _survivor_tail; }
142
143 // debugging
144 bool check_list_well_formed();
145 bool check_list_empty(bool check_sample = true);
146 void print();
147 };
148
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 };
157
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 };
170
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 };
179
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 };
188
189 class RefineCardTableEntryClosure;
190
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;
200
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;
217
218 // Other related classes.
219 friend class G1MarkSweep;
220
221 private:
222 // The one and only G1CollectedHeap, so static functions can find it.
223 static G1CollectedHeap* _g1h;
224
225 static size_t _humongous_object_threshold_in_words;
226
227 // Storage for the G1 heap (excludes the permanent generation).
228 VirtualSpace _g1_storage;
229 MemRegion _g1_reserved;
230
231 // The part of _g1_storage that is currently committed.
232 MemRegion _g1_committed;
233
234 // The master free list. It will satisfy all new region allocations.
235 MasterFreeRegionList _free_list;
236
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;
241
242 // It keeps track of the old regions.
243 MasterOldRegionSet _old_set;
244
245 // It keeps track of the humongous regions.
246 MasterHumongousRegionSet _humongous_set;
247
248 // The number of regions we could create by expansion.
249 size_t _expansion_regions;
250
251 // The block offset table for the G1 heap.
252 G1BlockOffsetSharedArray* _bot_shared;
253
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);
261
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);
269
270 // The sequence of all heap regions in the heap.
271 HeapRegionSeq _hrs;
272
273 // Alloc region used to satisfy mutator allocation requests.
274 MutatorAllocRegion _mutator_alloc_region;
275
276 // Alloc region used to satisfy allocation requests by the GC for
277 // survivor objects.
278 SurvivorGCAllocRegion _survivor_gc_alloc_region;
279
280 // Alloc region used to satisfy allocation requests by the GC for
281 // old objects.
282 OldGCAllocRegion _old_gc_alloc_region;
283
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;
287
288 // It specifies whether we should attempt to expand the heap after a
289 // region allocation failure. If heap expansion fails we set this to
290 // false so that we don't re-attempt the heap expansion (it's likely
291 // that subsequent expansion attempts will also fail if one fails).
292 // Currently, it is only consulted during GC and it's reset at the
293 // start of each GC.
294 bool _expand_heap_after_alloc_failure;
295
296 // It resets the mutator alloc region before new allocations can take place.
297 void init_mutator_alloc_region();
298
299 // It releases the mutator alloc region.
300 void release_mutator_alloc_region();
301
302 // It initializes the GC alloc regions at the start of a GC.
303 void init_gc_alloc_regions();
304
305 // It releases the GC alloc regions at the end of a GC.
306 void release_gc_alloc_regions();
307
308 // It does any cleanup that needs to be done on the GC alloc regions
309 // before a Full GC.
310 void abandon_gc_alloc_regions();
311
312 // Helper for monitoring and management support.
313 G1MonitoringSupport* _g1mm;
314
315 // Determines PLAB size for a particular allocation purpose.
316 static size_t desired_plab_sz(GCAllocPurpose purpose);
317
318 // Outside of GC pauses, the number of bytes used in all regions other
319 // than the current allocation region.
320 size_t _summary_bytes_used;
321
322 // This is used for a quick test on whether a reference points into
323 // the collection set or not. Basically, we have an array, with one
324 // byte per region, and that byte denotes whether the corresponding
325 // region is in the collection set or not. The entry corresponding
326 // the bottom of the heap, i.e., region 0, is pointed to by
327 // _in_cset_fast_test_base. The _in_cset_fast_test field has been
328 // biased so that it actually points to address 0 of the address
329 // space, to make the test as fast as possible (we can simply shift
330 // the address to address into it, instead of having to subtract the
331 // bottom of the heap from the address before shifting it; basically
332 // it works in the same way the card table works).
333 bool* _in_cset_fast_test;
334
335 // The allocated array used for the fast test on whether a reference
336 // points into the collection set or not. This field is also used to
337 // free the array.
338 bool* _in_cset_fast_test_base;
339
340 // The length of the _in_cset_fast_test_base array.
341 size_t _in_cset_fast_test_length;
342
343 volatile unsigned _gc_time_stamp;
344
345 size_t* _surviving_young_words;
346
347 G1HRPrinter _hr_printer;
348
349 void setup_surviving_young_words();
350 void update_surviving_young_words(size_t* surv_young_words);
351 void cleanup_surviving_young_words();
352
353 // It decides whether an explicit GC should start a concurrent cycle
354 // instead of doing a STW GC. Currently, a concurrent cycle is
355 // explicitly started if:
356 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
357 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
358 // (c) cause == _g1_humongous_allocation
359 bool should_do_concurrent_full_gc(GCCause::Cause cause);
360
361 // Keeps track of how many "full collections" (i.e., Full GCs or
362 // concurrent cycles) we have completed. The number of them we have
363 // started is maintained in _total_full_collections in CollectedHeap.
364 volatile unsigned int _full_collections_completed;
365
366 // This is a non-product method that is helpful for testing. It is
367 // called at the end of a GC and artificially expands the heap by
368 // allocating a number of dead regions. This way we can induce very
369 // frequent marking cycles and stress the cleanup / concurrent
370 // cleanup code more (as all the regions that will be allocated by
371 // this method will be found dead by the marking cycle).
372 void allocate_dummy_regions() PRODUCT_RETURN;
373
374 // These are macros so that, if the assert fires, we get the correct
375 // line number, file, etc.
376
377 #define heap_locking_asserts_err_msg(_extra_message_) \
378 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
379 (_extra_message_), \
380 BOOL_TO_STR(Heap_lock->owned_by_self()), \
381 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
382 BOOL_TO_STR(Thread::current()->is_VM_thread()))
383
384 #define assert_heap_locked() \
385 do { \
386 assert(Heap_lock->owned_by_self(), \
387 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \
388 } while (0)
389
390 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
391 do { \
392 assert(Heap_lock->owned_by_self() || \
393 (SafepointSynchronize::is_at_safepoint() && \
394 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
395 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
396 "should be at a safepoint")); \
397 } while (0)
398
399 #define assert_heap_locked_and_not_at_safepoint() \
400 do { \
401 assert(Heap_lock->owned_by_self() && \
402 !SafepointSynchronize::is_at_safepoint(), \
403 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \
404 "should not be at a safepoint")); \
405 } while (0)
406
407 #define assert_heap_not_locked() \
408 do { \
409 assert(!Heap_lock->owned_by_self(), \
410 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \
411 } while (0)
412
413 #define assert_heap_not_locked_and_not_at_safepoint() \
414 do { \
415 assert(!Heap_lock->owned_by_self() && \
416 !SafepointSynchronize::is_at_safepoint(), \
417 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \
418 "should not be at a safepoint")); \
419 } while (0)
420
421 #define assert_at_safepoint(_should_be_vm_thread_) \
422 do { \
423 assert(SafepointSynchronize::is_at_safepoint() && \
424 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
425 heap_locking_asserts_err_msg("should be at a safepoint")); \
426 } while (0)
427
428 #define assert_not_at_safepoint() \
429 do { \
430 assert(!SafepointSynchronize::is_at_safepoint(), \
431 heap_locking_asserts_err_msg("should not be at a safepoint")); \
432 } while (0)
433
434 protected:
435
436 // The young region list.
437 YoungList* _young_list;
438
439 // The current policy object for the collector.
440 G1CollectorPolicy* _g1_policy;
441
442 // This is the second level of trying to allocate a new region. If
443 // new_region() didn't find a region on the free_list, this call will
444 // check whether there's anything available on the
445 // secondary_free_list and/or wait for more regions to appear on
446 // that list, if _free_regions_coming is set.
447 HeapRegion* new_region_try_secondary_free_list();
448
449 // Try to allocate a single non-humongous HeapRegion sufficient for
450 // an allocation of the given word_size. If do_expand is true,
451 // attempt to expand the heap if necessary to satisfy the allocation
452 // request.
453 HeapRegion* new_region(size_t word_size, bool do_expand);
454
455 // Attempt to satisfy a humongous allocation request of the given
456 // size by finding a contiguous set of free regions of num_regions
457 // length and remove them from the master free list. Return the
458 // index of the first region or G1_NULL_HRS_INDEX if the search
459 // was unsuccessful.
460 size_t humongous_obj_allocate_find_first(size_t num_regions,
461 size_t word_size);
462
463 // Initialize a contiguous set of free regions of length num_regions
464 // and starting at index first so that they appear as a single
465 // humongous region.
466 HeapWord* humongous_obj_allocate_initialize_regions(size_t first,
467 size_t num_regions,
468 size_t word_size);
469
470 // Attempt to allocate a humongous object of the given size. Return
471 // NULL if unsuccessful.
472 HeapWord* humongous_obj_allocate(size_t word_size);
473
474 // The following two methods, allocate_new_tlab() and
475 // mem_allocate(), are the two main entry points from the runtime
476 // into the G1's allocation routines. They have the following
477 // assumptions:
478 //
479 // * They should both be called outside safepoints.
480 //
481 // * They should both be called without holding the Heap_lock.
482 //
483 // * All allocation requests for new TLABs should go to
484 // allocate_new_tlab().
485 //
486 // * All non-TLAB allocation requests should go to mem_allocate().
487 //
488 // * If either call cannot satisfy the allocation request using the
489 // current allocating region, they will try to get a new one. If
490 // this fails, they will attempt to do an evacuation pause and
491 // retry the allocation.
492 //
493 // * If all allocation attempts fail, even after trying to schedule
494 // an evacuation pause, allocate_new_tlab() will return NULL,
495 // whereas mem_allocate() will attempt a heap expansion and/or
496 // schedule a Full GC.
497 //
498 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
499 // should never be called with word_size being humongous. All
500 // humongous allocation requests should go to mem_allocate() which
501 // will satisfy them with a special path.
502
503 virtual HeapWord* allocate_new_tlab(size_t word_size);
504
505 virtual HeapWord* mem_allocate(size_t word_size,
506 bool* gc_overhead_limit_was_exceeded);
507
508 // The following three methods take a gc_count_before_ret
509 // parameter which is used to return the GC count if the method
510 // returns NULL. Given that we are required to read the GC count
511 // while holding the Heap_lock, and these paths will take the
512 // Heap_lock at some point, it's easier to get them to read the GC
513 // count while holding the Heap_lock before they return NULL instead
514 // of the caller (namely: mem_allocate()) having to also take the
515 // Heap_lock just to read the GC count.
516
517 // First-level mutator allocation attempt: try to allocate out of
518 // the mutator alloc region without taking the Heap_lock. This
519 // should only be used for non-humongous allocations.
520 inline HeapWord* attempt_allocation(size_t word_size,
521 unsigned int* gc_count_before_ret);
522
523 // Second-level mutator allocation attempt: take the Heap_lock and
524 // retry the allocation attempt, potentially scheduling a GC
525 // pause. This should only be used for non-humongous allocations.
526 HeapWord* attempt_allocation_slow(size_t word_size,
527 unsigned int* gc_count_before_ret);
528
529 // Takes the Heap_lock and attempts a humongous allocation. It can
530 // potentially schedule a GC pause.
531 HeapWord* attempt_allocation_humongous(size_t word_size,
532 unsigned int* gc_count_before_ret);
533
534 // Allocation attempt that should be called during safepoints (e.g.,
535 // at the end of a successful GC). expect_null_mutator_alloc_region
536 // specifies whether the mutator alloc region is expected to be NULL
537 // or not.
538 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
539 bool expect_null_mutator_alloc_region);
540
541 // It dirties the cards that cover the block so that so that the post
542 // write barrier never queues anything when updating objects on this
543 // block. It is assumed (and in fact we assert) that the block
544 // belongs to a young region.
545 inline void dirty_young_block(HeapWord* start, size_t word_size);
546
547 // Allocate blocks during garbage collection. Will ensure an
548 // allocation region, either by picking one or expanding the
549 // heap, and then allocate a block of the given size. The block
550 // may not be a humongous - it must fit into a single heap region.
551 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size);
552
553 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose,
554 HeapRegion* alloc_region,
555 bool par,
556 size_t word_size);
557
558 // Ensure that no further allocations can happen in "r", bearing in mind
559 // that parallel threads might be attempting allocations.
560 void par_allocate_remaining_space(HeapRegion* r);
561
562 // Allocation attempt during GC for a survivor object / PLAB.
563 inline HeapWord* survivor_attempt_allocation(size_t word_size);
564
565 // Allocation attempt during GC for an old object / PLAB.
566 inline HeapWord* old_attempt_allocation(size_t word_size);
567
568 // These methods are the "callbacks" from the G1AllocRegion class.
569
570 // For mutator alloc regions.
571 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
572 void retire_mutator_alloc_region(HeapRegion* alloc_region,
573 size_t allocated_bytes);
574
575 // For GC alloc regions.
576 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count,
577 GCAllocPurpose ap);
578 void retire_gc_alloc_region(HeapRegion* alloc_region,
579 size_t allocated_bytes, GCAllocPurpose ap);
580
581 // - if explicit_gc is true, the GC is for a System.gc() or a heap
582 // inspection request and should collect the entire heap
583 // - if clear_all_soft_refs is true, all soft references should be
584 // cleared during the GC
585 // - if explicit_gc is false, word_size describes the allocation that
586 // the GC should attempt (at least) to satisfy
587 // - it returns false if it is unable to do the collection due to the
588 // GC locker being active, true otherwise
589 bool do_collection(bool explicit_gc,
590 bool clear_all_soft_refs,
591 size_t word_size);
592
593 // Callback from VM_G1CollectFull operation.
594 // Perform a full collection.
595 void do_full_collection(bool clear_all_soft_refs);
596
597 // Resize the heap if necessary after a full collection. If this is
598 // after a collect-for allocation, "word_size" is the allocation size,
599 // and will be considered part of the used portion of the heap.
600 void resize_if_necessary_after_full_collection(size_t word_size);
601
602 // Callback from VM_G1CollectForAllocation operation.
603 // This function does everything necessary/possible to satisfy a
604 // failed allocation request (including collection, expansion, etc.)
605 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded);
606
607 // Attempting to expand the heap sufficiently
608 // to support an allocation of the given "word_size". If
609 // successful, perform the allocation and return the address of the
610 // allocated block, or else "NULL".
611 HeapWord* expand_and_allocate(size_t word_size);
612
613 // Process any reference objects discovered during
614 // an incremental evacuation pause.
615 void process_discovered_references();
616
617 // Enqueue any remaining discovered references
618 // after processing.
619 void enqueue_discovered_references();
620
621 public:
622
623 G1MonitoringSupport* g1mm() {
624 assert(_g1mm != NULL, "should have been initialized");
625 return _g1mm;
626 }
627
628 // Expand the garbage-first heap by at least the given size (in bytes!).
629 // Returns true if the heap was expanded by the requested amount;
630 // false otherwise.
631 // (Rounds up to a HeapRegion boundary.)
632 bool expand(size_t expand_bytes);
633
634 // Do anything common to GC's.
635 virtual void gc_prologue(bool full);
636 virtual void gc_epilogue(bool full);
637
638 // We register a region with the fast "in collection set" test. We
639 // simply set to true the array slot corresponding to this region.
640 void register_region_with_in_cset_fast_test(HeapRegion* r) {
641 assert(_in_cset_fast_test_base != NULL, "sanity");
642 assert(r->in_collection_set(), "invariant");
643 size_t index = r->hrs_index();
644 assert(index < _in_cset_fast_test_length, "invariant");
645 assert(!_in_cset_fast_test_base[index], "invariant");
646 _in_cset_fast_test_base[index] = true;
647 }
648
649 // This is a fast test on whether a reference points into the
650 // collection set or not. It does not assume that the reference
651 // points into the heap; if it doesn't, it will return false.
652 bool in_cset_fast_test(oop obj) {
653 assert(_in_cset_fast_test != NULL, "sanity");
654 if (_g1_committed.contains((HeapWord*) obj)) {
655 // no need to subtract the bottom of the heap from obj,
656 // _in_cset_fast_test is biased
657 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes;
658 bool ret = _in_cset_fast_test[index];
659 // let's make sure the result is consistent with what the slower
660 // test returns
661 assert( ret || !obj_in_cs(obj), "sanity");
662 assert(!ret || obj_in_cs(obj), "sanity");
663 return ret;
664 } else {
665 return false;
666 }
667 }
668
669 void clear_cset_fast_test() {
670 assert(_in_cset_fast_test_base != NULL, "sanity");
671 memset(_in_cset_fast_test_base, false,
672 _in_cset_fast_test_length * sizeof(bool));
673 }
674
675 // This is called at the end of either a concurrent cycle or a Full
676 // GC to update the number of full collections completed. Those two
677 // can happen in a nested fashion, i.e., we start a concurrent
678 // cycle, a Full GC happens half-way through it which ends first,
679 // and then the cycle notices that a Full GC happened and ends
680 // too. The concurrent parameter is a boolean to help us do a bit
681 // tighter consistency checking in the method. If concurrent is
682 // false, the caller is the inner caller in the nesting (i.e., the
683 // Full GC). If concurrent is true, the caller is the outer caller
684 // in this nesting (i.e., the concurrent cycle). Further nesting is
685 // not currently supported. The end of the this call also notifies
686 // the FullGCCount_lock in case a Java thread is waiting for a full
687 // GC to happen (e.g., it called System.gc() with
688 // +ExplicitGCInvokesConcurrent).
689 void increment_full_collections_completed(bool concurrent);
690
691 unsigned int full_collections_completed() {
692 return _full_collections_completed;
693 }
694
695 G1HRPrinter* hr_printer() { return &_hr_printer; }
696
697 protected:
698
699 // Shrink the garbage-first heap by at most the given size (in bytes!).
700 // (Rounds down to a HeapRegion boundary.)
701 virtual void shrink(size_t expand_bytes);
702 void shrink_helper(size_t expand_bytes);
703
704 #if TASKQUEUE_STATS
705 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty);
706 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const;
707 void reset_taskqueue_stats();
708 #endif // TASKQUEUE_STATS
709
710 // Schedule the VM operation that will do an evacuation pause to
711 // satisfy an allocation request of word_size. *succeeded will
712 // return whether the VM operation was successful (it did do an
713 // evacuation pause) or not (another thread beat us to it or the GC
714 // locker was active). Given that we should not be holding the
715 // Heap_lock when we enter this method, we will pass the
716 // gc_count_before (i.e., total_collections()) as a parameter since
717 // it has to be read while holding the Heap_lock. Currently, both
718 // methods that call do_collection_pause() release the Heap_lock
719 // before the call, so it's easy to read gc_count_before just before.
720 HeapWord* do_collection_pause(size_t word_size,
721 unsigned int gc_count_before,
722 bool* succeeded);
723
724 // The guts of the incremental collection pause, executed by the vm
725 // thread. It returns false if it is unable to do the collection due
726 // to the GC locker being active, true otherwise
727 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
728
729 // Actually do the work of evacuating the collection set.
730 void evacuate_collection_set();
731
732 // The g1 remembered set of the heap.
733 G1RemSet* _g1_rem_set;
734 // And it's mod ref barrier set, used to track updates for the above.
735 ModRefBarrierSet* _mr_bs;
736
737 // A set of cards that cover the objects for which the Rsets should be updated
738 // concurrently after the collection.
739 DirtyCardQueueSet _dirty_card_queue_set;
740
741 // The Heap Region Rem Set Iterator.
742 HeapRegionRemSetIterator** _rem_set_iterator;
743
744 // The closure used to refine a single card.
745 RefineCardTableEntryClosure* _refine_cte_cl;
746
747 // A function to check the consistency of dirty card logs.
748 void check_ct_logs_at_safepoint();
749
750 // A DirtyCardQueueSet that is used to hold cards that contain
751 // references into the current collection set. This is used to
752 // update the remembered sets of the regions in the collection
753 // set in the event of an evacuation failure.
754 DirtyCardQueueSet _into_cset_dirty_card_queue_set;
755
756 // After a collection pause, make the regions in the CS into free
757 // regions.
758 void free_collection_set(HeapRegion* cs_head);
759
760 // Abandon the current collection set without recording policy
761 // statistics or updating free lists.
762 void abandon_collection_set(HeapRegion* cs_head);
763
764 // Applies "scan_non_heap_roots" to roots outside the heap,
765 // "scan_rs" to roots inside the heap (having done "set_region" to
766 // indicate the region in which the root resides), and does "scan_perm"
767 // (setting the generation to the perm generation.) If "scan_rs" is
768 // NULL, then this step is skipped. The "worker_i"
769 // param is for use with parallel roots processing, and should be
770 // the "i" of the calling parallel worker thread's work(i) function.
771 // In the sequential case this param will be ignored.
772 void g1_process_strong_roots(bool collecting_perm_gen,
773 SharedHeap::ScanningOption so,
774 OopClosure* scan_non_heap_roots,
775 OopsInHeapRegionClosure* scan_rs,
776 OopsInGenClosure* scan_perm,
777 int worker_i);
778
779 // Apply "blk" to all the weak roots of the system. These include
780 // JNI weak roots, the code cache, system dictionary, symbol table,
781 // string table, and referents of reachable weak refs.
782 void g1_process_weak_roots(OopClosure* root_closure,
783 OopClosure* non_root_closure);
784
785 // Frees a non-humongous region by initializing its contents and
786 // adding it to the free list that's passed as a parameter (this is
787 // usually a local list which will be appended to the master free
788 // list later). The used bytes of freed regions are accumulated in
789 // pre_used. If par is true, the region's RSet will not be freed
790 // up. The assumption is that this will be done later.
791 void free_region(HeapRegion* hr,
792 size_t* pre_used,
793 FreeRegionList* free_list,
794 bool par);
795
796 // Frees a humongous region by collapsing it into individual regions
797 // and calling free_region() for each of them. The freed regions
798 // will be added to the free list that's passed as a parameter (this
799 // is usually a local list which will be appended to the master free
800 // list later). The used bytes of freed regions are accumulated in
801 // pre_used. If par is true, the region's RSet will not be freed
802 // up. The assumption is that this will be done later.
803 void free_humongous_region(HeapRegion* hr,
804 size_t* pre_used,
805 FreeRegionList* free_list,
806 HumongousRegionSet* humongous_proxy_set,
807 bool par);
808
809 // Notifies all the necessary spaces that the committed space has
810 // been updated (either expanded or shrunk). It should be called
811 // after _g1_storage is updated.
812 void update_committed_space(HeapWord* old_end, HeapWord* new_end);
813
814 // The concurrent marker (and the thread it runs in.)
815 ConcurrentMark* _cm;
816 ConcurrentMarkThread* _cmThread;
817 bool _mark_in_progress;
818
819 // The concurrent refiner.
820 ConcurrentG1Refine* _cg1r;
821
822 // The parallel task queues
823 RefToScanQueueSet *_task_queues;
824
825 // True iff a evacuation has failed in the current collection.
826 bool _evacuation_failed;
827
828 // Set the attribute indicating whether evacuation has failed in the
829 // current collection.
830 void set_evacuation_failed(bool b) { _evacuation_failed = b; }
831
832 // Failed evacuations cause some logical from-space objects to have
833 // forwarding pointers to themselves. Reset them.
834 void remove_self_forwarding_pointers();
835
836 // When one is non-null, so is the other. Together, they each pair is
837 // an object with a preserved mark, and its mark value.
838 GrowableArray<oop>* _objs_with_preserved_marks;
839 GrowableArray<markOop>* _preserved_marks_of_objs;
840
841 // Preserve the mark of "obj", if necessary, in preparation for its mark
842 // word being overwritten with a self-forwarding-pointer.
843 void preserve_mark_if_necessary(oop obj, markOop m);
844
845 // The stack of evac-failure objects left to be scanned.
846 GrowableArray<oop>* _evac_failure_scan_stack;
847 // The closure to apply to evac-failure objects.
848
849 OopsInHeapRegionClosure* _evac_failure_closure;
850 // Set the field above.
851 void
852 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) {
853 _evac_failure_closure = evac_failure_closure;
854 }
855
856 // Push "obj" on the scan stack.
857 void push_on_evac_failure_scan_stack(oop obj);
858 // Process scan stack entries until the stack is empty.
859 void drain_evac_failure_scan_stack();
860 // True iff an invocation of "drain_scan_stack" is in progress; to
861 // prevent unnecessary recursion.
862 bool _drain_in_progress;
863
864 // Do any necessary initialization for evacuation-failure handling.
865 // "cl" is the closure that will be used to process evac-failure
866 // objects.
867 void init_for_evac_failure(OopsInHeapRegionClosure* cl);
868 // Do any necessary cleanup for evacuation-failure handling data
869 // structures.
870 void finalize_for_evac_failure();
871
872 // An attempt to evacuate "obj" has failed; take necessary steps.
873 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj);
874 void handle_evacuation_failure_common(oop obj, markOop m);
875
876 // ("Weak") Reference processing support.
877 //
878 // G1 has 2 instances of the referece processor class. One
879 // (_ref_processor_cm) handles reference object discovery
880 // and subsequent processing during concurrent marking cycles.
881 //
882 // The other (_ref_processor_stw) handles reference object
883 // discovery and processing during full GCs and incremental
884 // evacuation pauses.
885 //
886 // During an incremental pause, reference discovery will be
887 // temporarily disabled for _ref_processor_cm and will be
888 // enabled for _ref_processor_stw. At the end of the evacuation
889 // pause references discovered by _ref_processor_stw will be
890 // processed and discovery will be disabled. The previous
891 // setting for reference object discovery for _ref_processor_cm
892 // will be re-instated.
893 //
894 // At the start of marking:
895 // * Discovery by the CM ref processor is verified to be inactive
896 // and it's discovered lists are empty.
897 // * Discovery by the CM ref processor is then enabled.
898 //
899 // At the end of marking:
900 // * Any references on the CM ref processor's discovered
901 // lists are processed (possibly MT).
902 //
903 // At the start of full GC we:
904 // * Disable discovery by the CM ref processor and
905 // empty CM ref processor's discovered lists
906 // (without processing any entries).
907 // * Verify that the STW ref processor is inactive and it's
908 // discovered lists are empty.
909 // * Temporarily set STW ref processor discovery as single threaded.
910 // * Temporarily clear the STW ref processor's _is_alive_non_header
911 // field.
912 // * Finally enable discovery by the STW ref processor.
913 //
914 // The STW ref processor is used to record any discovered
915 // references during the full GC.
916 //
917 // At the end of a full GC we:
918 // * Enqueue any reference objects discovered by the STW ref processor
919 // that have non-live referents. This has the side-effect of
920 // making the STW ref processor inactive by disabling discovery.
921 // * Verify that the CM ref processor is still inactive
922 // and no references have been placed on it's discovered
923 // lists (also checked as a precondition during initial marking).
924
925 // The (stw) reference processor...
926 ReferenceProcessor* _ref_processor_stw;
927
928 // During reference object discovery, the _is_alive_non_header
929 // closure (if non-null) is applied to the referent object to
930 // determine whether the referent is live. If so then the
931 // reference object does not need to be 'discovered' and can
932 // be treated as a regular oop. This has the benefit of reducing
933 // the number of 'discovered' reference objects that need to
934 // be processed.
935 //
936 // Instance of the is_alive closure for embedding into the
937 // STW reference processor as the _is_alive_non_header field.
938 // Supplying a value for the _is_alive_non_header field is
939 // optional but doing so prevents unnecessary additions to
940 // the discovered lists during reference discovery.
941 G1STWIsAliveClosure _is_alive_closure_stw;
942
943 // The (concurrent marking) reference processor...
944 ReferenceProcessor* _ref_processor_cm;
945
946 // Instance of the concurrent mark is_alive closure for embedding
947 // into the Concurrent Marking reference processor as the
948 // _is_alive_non_header field. Supplying a value for the
949 // _is_alive_non_header field is optional but doing so prevents
950 // unnecessary additions to the discovered lists during reference
951 // discovery.
952 G1CMIsAliveClosure _is_alive_closure_cm;
953
954 // Cache used by G1CollectedHeap::start_cset_region_for_worker().
955 HeapRegion** _worker_cset_start_region;
956
957 // Time stamp to validate the regions recorded in the cache
958 // used by G1CollectedHeap::start_cset_region_for_worker().
959 // The heap region entry for a given worker is valid iff
960 // the associated time stamp value matches the current value
961 // of G1CollectedHeap::_gc_time_stamp.
962 unsigned int* _worker_cset_start_region_time_stamp;
963
964 enum G1H_process_strong_roots_tasks {
965 G1H_PS_filter_satb_buffers,
966 G1H_PS_refProcessor_oops_do,
967 // Leave this one last.
968 G1H_PS_NumElements
969 };
970
971 SubTasksDone* _process_strong_tasks;
972
973 volatile bool _free_regions_coming;
974
975 public:
976
977 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
978
979 void set_refine_cte_cl_concurrency(bool concurrent);
980
981 RefToScanQueue *task_queue(int i) const;
982
983 // A set of cards where updates happened during the GC
984 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
985
986 // A DirtyCardQueueSet that is used to hold cards that contain
987 // references into the current collection set. This is used to
988 // update the remembered sets of the regions in the collection
989 // set in the event of an evacuation failure.
990 DirtyCardQueueSet& into_cset_dirty_card_queue_set()
991 { return _into_cset_dirty_card_queue_set; }
992
993 // Create a G1CollectedHeap with the specified policy.
994 // Must call the initialize method afterwards.
995 // May not return if something goes wrong.
996 G1CollectedHeap(G1CollectorPolicy* policy);
997
998 // Initialize the G1CollectedHeap to have the initial and
999 // maximum sizes, permanent generation, and remembered and barrier sets
1000 // specified by the policy object.
1001 jint initialize();
1002
1003 // Initialize weak reference processing.
1004 virtual void ref_processing_init();
1005
1006 void set_par_threads(uint t) {
1007 SharedHeap::set_par_threads(t);
1008 // Done in SharedHeap but oddly there are
1009 // two _process_strong_tasks's in a G1CollectedHeap
1010 // so do it here too.
1011 _process_strong_tasks->set_n_threads(t);
1012 }
1013
1014 // Set _n_par_threads according to a policy TBD.
1015 void set_par_threads();
1016
1017 void set_n_termination(int t) {
1018 _process_strong_tasks->set_n_threads(t);
1019 }
1020
1021 virtual CollectedHeap::Name kind() const {
1022 return CollectedHeap::G1CollectedHeap;
1023 }
1024
1025 // The current policy object for the collector.
1026 G1CollectorPolicy* g1_policy() const { return _g1_policy; }
1027
1028 // Adaptive size policy. No such thing for g1.
1029 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1030
1031 // The rem set and barrier set.
1032 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1033 ModRefBarrierSet* mr_bs() const { return _mr_bs; }
1034
1035 // The rem set iterator.
1036 HeapRegionRemSetIterator* rem_set_iterator(int i) {
1037 return _rem_set_iterator[i];
1038 }
1039
1040 HeapRegionRemSetIterator* rem_set_iterator() {
1041 return _rem_set_iterator[0];
1042 }
1043
1044 unsigned get_gc_time_stamp() {
1045 return _gc_time_stamp;
1046 }
1047
1048 void reset_gc_time_stamp() {
1049 _gc_time_stamp = 0;
1050 OrderAccess::fence();
1051 // Clear the cached CSet starting regions and time stamps.
1052 // Their validity is dependent on the GC timestamp.
1053 clear_cset_start_regions();
1054 }
1055
1056 void increment_gc_time_stamp() {
1057 ++_gc_time_stamp;
1058 OrderAccess::fence();
1059 }
1060
1061 void iterate_dirty_card_closure(CardTableEntryClosure* cl,
1062 DirtyCardQueue* into_cset_dcq,
1063 bool concurrent, int worker_i);
1064
1065 // The shared block offset table array.
1066 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; }
1067
1068 // Reference Processing accessors
1069
1070 // The STW reference processor....
1071 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1072
1073 // The Concurent Marking reference processor...
1074 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1075
1076 virtual size_t capacity() const;
1077 virtual size_t used() const;
1078 // This should be called when we're not holding the heap lock. The
1079 // result might be a bit inaccurate.
1080 size_t used_unlocked() const;
1081 size_t recalculate_used() const;
1082
1083 // These virtual functions do the actual allocation.
1084 // Some heaps may offer a contiguous region for shared non-blocking
1085 // allocation, via inlined code (by exporting the address of the top and
1086 // end fields defining the extent of the contiguous allocation region.)
1087 // But G1CollectedHeap doesn't yet support this.
1088
1089 // Return an estimate of the maximum allocation that could be performed
1090 // without triggering any collection or expansion activity. In a
1091 // generational collector, for example, this is probably the largest
1092 // allocation that could be supported (without expansion) in the youngest
1093 // generation. It is "unsafe" because no locks are taken; the result
1094 // should be treated as an approximation, not a guarantee, for use in
1095 // heuristic resizing decisions.
1096 virtual size_t unsafe_max_alloc();
1097
1098 virtual bool is_maximal_no_gc() const {
1099 return _g1_storage.uncommitted_size() == 0;
1100 }
1101
1102 // The total number of regions in the heap.
1103 size_t n_regions() { return _hrs.length(); }
1104
1105 // The max number of regions in the heap.
1106 size_t max_regions() { return _hrs.max_length(); }
1107
1108 // The number of regions that are completely free.
1109 size_t free_regions() { return _free_list.length(); }
1110
1111 // The number of regions that are not completely free.
1112 size_t used_regions() { return n_regions() - free_regions(); }
1113
1114 // The number of regions available for "regular" expansion.
1115 size_t expansion_regions() { return _expansion_regions; }
1116
1117 // Factory method for HeapRegion instances. It will return NULL if
1118 // the allocation fails.
1119 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom);
1120
1121 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1122 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
1123 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN;
1124 void verify_dirty_young_regions() PRODUCT_RETURN;
1125
1126 // verify_region_sets() performs verification over the region
1127 // lists. It will be compiled in the product code to be used when
1128 // necessary (i.e., during heap verification).
1129 void verify_region_sets();
1130
1131 // verify_region_sets_optional() is planted in the code for
1132 // list verification in non-product builds (and it can be enabled in
1133 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1).
1134 #if HEAP_REGION_SET_FORCE_VERIFY
1135 void verify_region_sets_optional() {
1136 verify_region_sets();
1137 }
1138 #else // HEAP_REGION_SET_FORCE_VERIFY
1139 void verify_region_sets_optional() { }
1140 #endif // HEAP_REGION_SET_FORCE_VERIFY
1141
1142 #ifdef ASSERT
1143 bool is_on_master_free_list(HeapRegion* hr) {
1144 return hr->containing_set() == &_free_list;
1145 }
1146
1147 bool is_in_humongous_set(HeapRegion* hr) {
1148 return hr->containing_set() == &_humongous_set;
1149 }
1150 #endif // ASSERT
1151
1152 // Wrapper for the region list operations that can be called from
1153 // methods outside this class.
1154
1155 void secondary_free_list_add_as_tail(FreeRegionList* list) {
1156 _secondary_free_list.add_as_tail(list);
1157 }
1158
1159 void append_secondary_free_list() {
1160 _free_list.add_as_head(&_secondary_free_list);
1161 }
1162
1163 void append_secondary_free_list_if_not_empty_with_lock() {
1164 // If the secondary free list looks empty there's no reason to
1165 // take the lock and then try to append it.
1166 if (!_secondary_free_list.is_empty()) {
1167 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1168 append_secondary_free_list();
1169 }
1170 }
1171
1172 void old_set_remove(HeapRegion* hr) {
1173 _old_set.remove(hr);
1174 }
1175
1176 size_t non_young_capacity_bytes() {
1177 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes();
1178 }
1179
1180 void set_free_regions_coming();
1181 void reset_free_regions_coming();
1182 bool free_regions_coming() { return _free_regions_coming; }
1183 void wait_while_free_regions_coming();
1184
1185 // Perform a collection of the heap; intended for use in implementing
1186 // "System.gc". This probably implies as full a collection as the
1187 // "CollectedHeap" supports.
1188 virtual void collect(GCCause::Cause cause);
1189
1190 // The same as above but assume that the caller holds the Heap_lock.
1191 void collect_locked(GCCause::Cause cause);
1192
1193 // This interface assumes that it's being called by the
1194 // vm thread. It collects the heap assuming that the
1195 // heap lock is already held and that we are executing in
1196 // the context of the vm thread.
1197 virtual void collect_as_vm_thread(GCCause::Cause cause);
1198
1199 // True iff a evacuation has failed in the most-recent collection.
1200 bool evacuation_failed() { return _evacuation_failed; }
1201
1202 // It will free a region if it has allocated objects in it that are
1203 // all dead. It calls either free_region() or
1204 // free_humongous_region() depending on the type of the region that
1205 // is passed to it.
1206 void free_region_if_empty(HeapRegion* hr,
1207 size_t* pre_used,
1208 FreeRegionList* free_list,
1209 OldRegionSet* old_proxy_set,
1210 HumongousRegionSet* humongous_proxy_set,
1211 HRRSCleanupTask* hrrs_cleanup_task,
1212 bool par);
1213
1214 // It appends the free list to the master free list and updates the
1215 // master humongous list according to the contents of the proxy
1216 // list. It also adjusts the total used bytes according to pre_used
1217 // (if par is true, it will do so by taking the ParGCRareEvent_lock).
1218 void update_sets_after_freeing_regions(size_t pre_used,
1219 FreeRegionList* free_list,
1220 OldRegionSet* old_proxy_set,
1221 HumongousRegionSet* humongous_proxy_set,
1222 bool par);
1223
1224 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1225 virtual bool is_in(const void* p) const;
1226
1227 // Return "TRUE" iff the given object address is within the collection
1228 // set.
1229 inline bool obj_in_cs(oop obj);
1230
1231 // Return "TRUE" iff the given object address is in the reserved
1232 // region of g1 (excluding the permanent generation).
1233 bool is_in_g1_reserved(const void* p) const {
1234 return _g1_reserved.contains(p);
1235 }
1236
1237 // Returns a MemRegion that corresponds to the space that has been
1238 // reserved for the heap
1239 MemRegion g1_reserved() {
1240 return _g1_reserved;
1241 }
1242
1243 // Returns a MemRegion that corresponds to the space that has been
1244 // committed in the heap
1245 MemRegion g1_committed() {
1246 return _g1_committed;
1247 }
1248
1249 virtual bool is_in_closed_subset(const void* p) const;
1250
1251 // This resets the card table to all zeros. It is used after
1252 // a collection pause which used the card table to claim cards.
1253 void cleanUpCardTable();
1254
1255 // Iteration functions.
1256
1257 // Iterate over all the ref-containing fields of all objects, calling
1258 // "cl.do_oop" on each.
1259 virtual void oop_iterate(OopClosure* cl) {
1260 oop_iterate(cl, true);
1261 }
1262 void oop_iterate(OopClosure* cl, bool do_perm);
1263
1264 // Same as above, restricted to a memory region.
1265 virtual void oop_iterate(MemRegion mr, OopClosure* cl) {
1266 oop_iterate(mr, cl, true);
1267 }
1268 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm);
1269
1270 // Iterate over all objects, calling "cl.do_object" on each.
1271 virtual void object_iterate(ObjectClosure* cl) {
1272 object_iterate(cl, true);
1273 }
1274 virtual void safe_object_iterate(ObjectClosure* cl) {
1275 object_iterate(cl, true);
1276 }
1277 void object_iterate(ObjectClosure* cl, bool do_perm);
1278
1279 // Iterate over all objects allocated since the last collection, calling
1280 // "cl.do_object" on each. The heap must have been initialized properly
1281 // to support this function, or else this call will fail.
1282 virtual void object_iterate_since_last_GC(ObjectClosure* cl);
1283
1284 // Iterate over all spaces in use in the heap, in ascending address order.
1285 virtual void space_iterate(SpaceClosure* cl);
1286
1287 // Iterate over heap regions, in address order, terminating the
1288 // iteration early if the "doHeapRegion" method returns "true".
1289 void heap_region_iterate(HeapRegionClosure* blk) const;
1290
1291 // Iterate over heap regions starting with r (or the first region if "r"
1292 // is NULL), in address order, terminating early if the "doHeapRegion"
1293 // method returns "true".
1294 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const;
1295
1296 // Return the region with the given index. It assumes the index is valid.
1297 HeapRegion* region_at(size_t index) const { return _hrs.at(index); }
1298
1299 // Divide the heap region sequence into "chunks" of some size (the number
1300 // of regions divided by the number of parallel threads times some
1301 // overpartition factor, currently 4). Assumes that this will be called
1302 // in parallel by ParallelGCThreads worker threads with discinct worker
1303 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel
1304 // calls will use the same "claim_value", and that that claim value is
1305 // different from the claim_value of any heap region before the start of
1306 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by
1307 // attempting to claim the first region in each chunk, and, if
1308 // successful, applying the closure to each region in the chunk (and
1309 // setting the claim value of the second and subsequent regions of the
1310 // chunk.) For now requires that "doHeapRegion" always returns "false",
1311 // i.e., that a closure never attempt to abort a traversal.
1312 void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
1313 uint worker,
1314 uint no_of_par_workers,
1315 jint claim_value);
1316
1317 // It resets all the region claim values to the default.
1318 void reset_heap_region_claim_values();
1319
1320 // Resets the claim values of regions in the current
1321 // collection set to the default.
1322 void reset_cset_heap_region_claim_values();
1323
1324 #ifdef ASSERT
1325 bool check_heap_region_claim_values(jint claim_value);
1326
1327 // Same as the routine above but only checks regions in the
1328 // current collection set.
1329 bool check_cset_heap_region_claim_values(jint claim_value);
1330 #endif // ASSERT
1331
1332 // Clear the cached cset start regions and (more importantly)
1333 // the time stamps. Called when we reset the GC time stamp.
1334 void clear_cset_start_regions();
1335
1336 // Given the id of a worker, obtain or calculate a suitable
1337 // starting region for iterating over the current collection set.
1338 HeapRegion* start_cset_region_for_worker(int worker_i);
1339
1340 // Iterate over the regions (if any) in the current collection set.
1341 void collection_set_iterate(HeapRegionClosure* blk);
1342
1343 // As above but starting from region r
1344 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
1345
1346 // Returns the first (lowest address) compactible space in the heap.
1347 virtual CompactibleSpace* first_compactible_space();
1348
1349 // A CollectedHeap will contain some number of spaces. This finds the
1350 // space containing a given address, or else returns NULL.
1351 virtual Space* space_containing(const void* addr) const;
1352
1353 // A G1CollectedHeap will contain some number of heap regions. This
1354 // finds the region containing a given address, or else returns NULL.
1355 template <class T>
1356 inline HeapRegion* heap_region_containing(const T addr) const;
1357
1358 // Like the above, but requires "addr" to be in the heap (to avoid a
1359 // null-check), and unlike the above, may return an continuing humongous
1360 // region.
1361 template <class T>
1362 inline HeapRegion* heap_region_containing_raw(const T addr) const;
1363
1364 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1365 // each address in the (reserved) heap is a member of exactly
1366 // one block. The defining characteristic of a block is that it is
1367 // possible to find its size, and thus to progress forward to the next
1368 // block. (Blocks may be of different sizes.) Thus, blocks may
1369 // represent Java objects, or they might be free blocks in a
1370 // free-list-based heap (or subheap), as long as the two kinds are
1371 // distinguishable and the size of each is determinable.
1372
1373 // Returns the address of the start of the "block" that contains the
1374 // address "addr". We say "blocks" instead of "object" since some heaps
1375 // may not pack objects densely; a chunk may either be an object or a
1376 // non-object.
1377 virtual HeapWord* block_start(const void* addr) const;
1378
1379 // Requires "addr" to be the start of a chunk, and returns its size.
1380 // "addr + size" is required to be the start of a new chunk, or the end
1381 // of the active area of the heap.
1382 virtual size_t block_size(const HeapWord* addr) const;
1383
1384 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1385 // the block is an object.
1386 virtual bool block_is_obj(const HeapWord* addr) const;
1387
1388 // Does this heap support heap inspection? (+PrintClassHistogram)
1389 virtual bool supports_heap_inspection() const { return true; }
1390
1391 // Section on thread-local allocation buffers (TLABs)
1392 // See CollectedHeap for semantics.
1393
1394 virtual bool supports_tlab_allocation() const;
1395 virtual size_t tlab_capacity(Thread* thr) const;
1396 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
1397
1398 // Can a compiler initialize a new object without store barriers?
1399 // This permission only extends from the creation of a new object
1400 // via a TLAB up to the first subsequent safepoint. If such permission
1401 // is granted for this heap type, the compiler promises to call
1402 // defer_store_barrier() below on any slow path allocation of
1403 // a new object for which such initializing store barriers will
1404 // have been elided. G1, like CMS, allows this, but should be
1405 // ready to provide a compensating write barrier as necessary
1406 // if that storage came out of a non-young region. The efficiency
1407 // of this implementation depends crucially on being able to
1408 // answer very efficiently in constant time whether a piece of
1409 // storage in the heap comes from a young region or not.
1410 // See ReduceInitialCardMarks.
1411 virtual bool can_elide_tlab_store_barriers() const {
1412 return true;
1413 }
1414
1415 virtual bool card_mark_must_follow_store() const {
1416 return true;
1417 }
1418
1419 bool is_in_young(const oop obj) {
1420 HeapRegion* hr = heap_region_containing(obj);
1421 return hr != NULL && hr->is_young();
1422 }
1423
1424 #ifdef ASSERT
1425 virtual bool is_in_partial_collection(const void* p);
1426 #endif
1427
1428 virtual bool is_scavengable(const void* addr);
1429
1430 // We don't need barriers for initializing stores to objects
1431 // in the young gen: for the SATB pre-barrier, there is no
1432 // pre-value that needs to be remembered; for the remembered-set
1433 // update logging post-barrier, we don't maintain remembered set
1434 // information for young gen objects.
1435 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
1436 return is_in_young(new_obj);
1437 }
1438
1439 // Can a compiler elide a store barrier when it writes
1440 // a permanent oop into the heap? Applies when the compiler
1441 // is storing x to the heap, where x->is_perm() is true.
1442 virtual bool can_elide_permanent_oop_store_barriers() const {
1443 // At least until perm gen collection is also G1-ified, at
1444 // which point this should return false.
1445 return true;
1446 }
1447
1448 // Returns "true" iff the given word_size is "very large".
1449 static bool isHumongous(size_t word_size) {
1450 // Note this has to be strictly greater-than as the TLABs
1451 // are capped at the humongous thresold and we want to
1452 // ensure that we don't try to allocate a TLAB as
1453 // humongous and that we don't allocate a humongous
1454 // object in a TLAB.
1455 return word_size > _humongous_object_threshold_in_words;
1456 }
1457
1458 // Update mod union table with the set of dirty cards.
1459 void updateModUnion();
1460
1461 // Set the mod union bits corresponding to the given memRegion. Note
1462 // that this is always a safe operation, since it doesn't clear any
1463 // bits.
1464 void markModUnionRange(MemRegion mr);
1465
1466 // Records the fact that a marking phase is no longer in progress.
1467 void set_marking_complete() {
1468 _mark_in_progress = false;
1469 }
1470 void set_marking_started() {
1471 _mark_in_progress = true;
1472 }
1473 bool mark_in_progress() {
1474 return _mark_in_progress;
1475 }
1476
1477 // Print the maximum heap capacity.
1478 virtual size_t max_capacity() const;
1479
1480 virtual jlong millis_since_last_gc();
1481
1482 // Perform any cleanup actions necessary before allowing a verification.
1483 virtual void prepare_for_verify();
1484
1485 // Perform verification.
1486
1487 // vo == UsePrevMarking -> use "prev" marking information,
1488 // vo == UseNextMarking -> use "next" marking information
1489 // vo == UseMarkWord -> use the mark word in the object header
1490 //
1491 // NOTE: Only the "prev" marking information is guaranteed to be
1492 // consistent most of the time, so most calls to this should use
1493 // vo == UsePrevMarking.
1494 // Currently, there is only one case where this is called with
1495 // vo == UseNextMarking, which is to verify the "next" marking
1496 // information at the end of remark.
1497 // Currently there is only one place where this is called with
1498 // vo == UseMarkWord, which is to verify the marking during a
1499 // full GC.
1500 void verify(bool allow_dirty, bool silent, VerifyOption vo);
1501
1502 // Override; it uses the "prev" marking information
1503 virtual void verify(bool allow_dirty, bool silent);
1504 virtual void print_on(outputStream* st) const;
1505 virtual void print_extended_on(outputStream* st) const;
1506
1507 virtual void print_gc_threads_on(outputStream* st) const;
1508 virtual void gc_threads_do(ThreadClosure* tc) const;
1509
1510 // Override
1511 void print_tracing_info() const;
1512
1513 // The following two methods are helpful for debugging RSet issues.
1514 void print_cset_rsets() PRODUCT_RETURN;
1515 void print_all_rsets() PRODUCT_RETURN;
1516
1517 // Convenience function to be used in situations where the heap type can be
1518 // asserted to be this type.
1519 static G1CollectedHeap* heap();
1520
1521 void set_region_short_lived_locked(HeapRegion* hr);
1522 // add appropriate methods for any other surv rate groups
1523
1524 YoungList* young_list() { return _young_list; }
1525
1526 // debugging
1527 bool check_young_list_well_formed() {
1528 return _young_list->check_list_well_formed();
1529 }
1530
1531 bool check_young_list_empty(bool check_heap,
1532 bool check_sample = true);
1533
1534 // *** Stuff related to concurrent marking. It's not clear to me that so
1535 // many of these need to be public.
1536
1537 // The functions below are helper functions that a subclass of
1538 // "CollectedHeap" can use in the implementation of its virtual
1539 // functions.
1540 // This performs a concurrent marking of the live objects in a
1541 // bitmap off to the side.
1542 void doConcurrentMark();
1543
1544 bool isMarkedPrev(oop obj) const;
1545 bool isMarkedNext(oop obj) const;
1546
1547 // vo == UsePrevMarking -> use "prev" marking information,
1548 // vo == UseNextMarking -> use "next" marking information,
1549 // vo == UseMarkWord -> use mark word from object header
1550 bool is_obj_dead_cond(const oop obj,
1551 const HeapRegion* hr,
1552 const VerifyOption vo) const {
1553
1554 switch (vo) {
1555 case VerifyOption_G1UsePrevMarking:
1556 return is_obj_dead(obj, hr);
1557 case VerifyOption_G1UseNextMarking:
1558 return is_obj_ill(obj, hr);
1559 default:
1560 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1561 return !obj->is_gc_marked();
1562 }
1563 }
1564
1565 // Determine if an object is dead, given the object and also
1566 // the region to which the object belongs. An object is dead
1567 // iff a) it was not allocated since the last mark and b) it
1568 // is not marked.
1569
1570 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1571 return
1572 !hr->obj_allocated_since_prev_marking(obj) &&
1573 !isMarkedPrev(obj);
1574 }
1575
1576 // This is used when copying an object to survivor space.
1577 // If the object is marked live, then we mark the copy live.
1578 // If the object is allocated since the start of this mark
1579 // cycle, then we mark the copy live.
1580 // If the object has been around since the previous mark
1581 // phase, and hasn't been marked yet during this phase,
1582 // then we don't mark it, we just wait for the
1583 // current marking cycle to get to it.
1584
1585 // This function returns true when an object has been
1586 // around since the previous marking and hasn't yet
1587 // been marked during this marking.
1588
1589 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1590 return
1591 !hr->obj_allocated_since_next_marking(obj) &&
1592 !isMarkedNext(obj);
1593 }
1594
1595 // Determine if an object is dead, given only the object itself.
1596 // This will find the region to which the object belongs and
1597 // then call the region version of the same function.
1598
1599 // Added if it is in permanent gen it isn't dead.
1600 // Added if it is NULL it isn't dead.
1601
1602 // vo == UsePrevMarking -> use "prev" marking information,
1603 // vo == UseNextMarking -> use "next" marking information,
1604 // vo == UseMarkWord -> use mark word from object header
1605 bool is_obj_dead_cond(const oop obj,
1606 const VerifyOption vo) const {
1607
1608 switch (vo) {
1609 case VerifyOption_G1UsePrevMarking:
1610 return is_obj_dead(obj);
1611 case VerifyOption_G1UseNextMarking:
1612 return is_obj_ill(obj);
1613 default:
1614 assert(vo == VerifyOption_G1UseMarkWord, "must be");
1615 return !obj->is_gc_marked();
1616 }
1617 }
1618
1619 bool is_obj_dead(const oop obj) const {
1620 const HeapRegion* hr = heap_region_containing(obj);
1621 if (hr == NULL) {
1622 if (Universe::heap()->is_in_permanent(obj))
1623 return false;
1624 else if (obj == NULL) return false;
1625 else return true;
1626 }
1627 else return is_obj_dead(obj, hr);
1628 }
1629
1630 bool is_obj_ill(const oop obj) const {
1631 const HeapRegion* hr = heap_region_containing(obj);
1632 if (hr == NULL) {
1633 if (Universe::heap()->is_in_permanent(obj))
1634 return false;
1635 else if (obj == NULL) return false;
1636 else return true;
1637 }
1638 else return is_obj_ill(obj, hr);
1639 }
1640
1641 // The following is just to alert the verification code
1642 // that a full collection has occurred and that the
1643 // remembered sets are no longer up to date.
1644 bool _full_collection;
1645 void set_full_collection() { _full_collection = true;}
1646 void clear_full_collection() {_full_collection = false;}
1647 bool full_collection() {return _full_collection;}
1648
1649 ConcurrentMark* concurrent_mark() const { return _cm; }
1650 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1651
1652 // The dirty cards region list is used to record a subset of regions
1653 // whose cards need clearing. The list if populated during the
1654 // remembered set scanning and drained during the card table
1655 // cleanup. Although the methods are reentrant, population/draining
1656 // phases must not overlap. For synchronization purposes the last
1657 // element on the list points to itself.
1658 HeapRegion* _dirty_cards_region_list;
1659 void push_dirty_cards_region(HeapRegion* hr);
1660 HeapRegion* pop_dirty_cards_region();
1661
1662 public:
1663 void stop_conc_gc_threads();
1664
1665 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
1666 void check_if_region_is_too_expensive(double predicted_time_ms);
1667 size_t pending_card_num();
1668 size_t max_pending_card_num();
1669 size_t cards_scanned();
1670
1671 protected:
1672 size_t _max_heap_capacity;
1673 };
1674
1675 #define use_local_bitmaps 1
1676 #define verify_local_bitmaps 0
1677 #define oop_buffer_length 256
1678
1679 #ifndef PRODUCT
1680 class GCLabBitMap;
1681 class GCLabBitMapClosure: public BitMapClosure {
1682 private:
1683 ConcurrentMark* _cm;
1684 GCLabBitMap* _bitmap;
1685
1686 public:
1687 GCLabBitMapClosure(ConcurrentMark* cm,
1688 GCLabBitMap* bitmap) {
1689 _cm = cm;
1690 _bitmap = bitmap;
1691 }
1692
1693 virtual bool do_bit(size_t offset);
1694 };
1695 #endif // !PRODUCT
1696
1697 class GCLabBitMap: public BitMap {
1698 private:
1699 ConcurrentMark* _cm;
1700
1701 int _shifter;
1702 size_t _bitmap_word_covers_words;
1703
1704 // beginning of the heap
1705 HeapWord* _heap_start;
1706
1707 // this is the actual start of the GCLab
1708 HeapWord* _real_start_word;
1709
1710 // this is the actual end of the GCLab
1711 HeapWord* _real_end_word;
1712
1713 // this is the first word, possibly located before the actual start
1714 // of the GCLab, that corresponds to the first bit of the bitmap
1715 HeapWord* _start_word;
1716
1717 // size of a GCLab in words
1718 size_t _gclab_word_size;
1719
1720 static int shifter() {
1721 return MinObjAlignment - 1;
1722 }
1723
1724 // how many heap words does a single bitmap word corresponds to?
1725 static size_t bitmap_word_covers_words() {
1726 return BitsPerWord << shifter();
1727 }
1728
1729 size_t gclab_word_size() const {
1730 return _gclab_word_size;
1731 }
1732
1733 // Calculates actual GCLab size in words
1734 size_t gclab_real_word_size() const {
1735 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word))
1736 / BitsPerWord;
1737 }
1738
1739 static size_t bitmap_size_in_bits(size_t gclab_word_size) {
1740 size_t bits_in_bitmap = gclab_word_size >> shifter();
1741 // We are going to ensure that the beginning of a word in this
1742 // bitmap also corresponds to the beginning of a word in the
1743 // global marking bitmap. To handle the case where a GCLab
1744 // starts from the middle of the bitmap, we need to add enough
1745 // space (i.e. up to a bitmap word) to ensure that we have
1746 // enough bits in the bitmap.
1747 return bits_in_bitmap + BitsPerWord - 1;
1748 }
1749 public:
1750 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size)
1751 : BitMap(bitmap_size_in_bits(gclab_word_size)),
1752 _cm(G1CollectedHeap::heap()->concurrent_mark()),
1753 _shifter(shifter()),
1754 _bitmap_word_covers_words(bitmap_word_covers_words()),
1755 _heap_start(heap_start),
1756 _gclab_word_size(gclab_word_size),
1757 _real_start_word(NULL),
1758 _real_end_word(NULL),
1759 _start_word(NULL) {
1760 guarantee(false, "GCLabBitMap::GCLabBitmap(): don't call this any more");
1761 }
1762
1763 inline unsigned heapWordToOffset(HeapWord* addr) {
1764 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter;
1765 assert(offset < size(), "offset should be within bounds");
1766 return offset;
1767 }
1768
1769 inline HeapWord* offsetToHeapWord(size_t offset) {
1770 HeapWord* addr = _start_word + (offset << _shifter);
1771 assert(_real_start_word <= addr && addr < _real_end_word, "invariant");
1772 return addr;
1773 }
1774
1775 bool fields_well_formed() {
1776 bool ret1 = (_real_start_word == NULL) &&
1777 (_real_end_word == NULL) &&
1778 (_start_word == NULL);
1779 if (ret1)
1780 return true;
1781
1782 bool ret2 = _real_start_word >= _start_word &&
1783 _start_word < _real_end_word &&
1784 (_real_start_word + _gclab_word_size) == _real_end_word &&
1785 (_start_word + _gclab_word_size + _bitmap_word_covers_words)
1786 > _real_end_word;
1787 return ret2;
1788 }
1789
1790 inline bool mark(HeapWord* addr) {
1791 guarantee(use_local_bitmaps, "invariant");
1792 assert(fields_well_formed(), "invariant");
1793
1794 if (addr >= _real_start_word && addr < _real_end_word) {
1795 assert(!isMarked(addr), "should not have already been marked");
1796
1797 // first mark it on the bitmap
1798 at_put(heapWordToOffset(addr), true);
1799
1800 return true;
1801 } else {
1802 return false;
1803 }
1804 }
1805
1806 inline bool isMarked(HeapWord* addr) {
1807 guarantee(use_local_bitmaps, "invariant");
1808 assert(fields_well_formed(), "invariant");
1809
1810 return at(heapWordToOffset(addr));
1811 }
1812
1813 void set_buffer(HeapWord* start) {
1814 guarantee(false, "set_buffer(): don't call this any more");
1815
1816 guarantee(use_local_bitmaps, "invariant");
1817 clear();
1818
1819 assert(start != NULL, "invariant");
1820 _real_start_word = start;
1821 _real_end_word = start + _gclab_word_size;
1822
1823 size_t diff =
1824 pointer_delta(start, _heap_start) % _bitmap_word_covers_words;
1825 _start_word = start - diff;
1826
1827 assert(fields_well_formed(), "invariant");
1828 }
1829
1830 #ifndef PRODUCT
1831 void verify() {
1832 // verify that the marks have been propagated
1833 GCLabBitMapClosure cl(_cm, this);
1834 iterate(&cl);
1835 }
1836 #endif // PRODUCT
1837
1838 void retire() {
1839 guarantee(false, "retire(): don't call this any more");
1840
1841 guarantee(use_local_bitmaps, "invariant");
1842 assert(fields_well_formed(), "invariant");
1843
1844 if (_start_word != NULL) {
1845 CMBitMap* mark_bitmap = _cm->nextMarkBitMap();
1846
1847 // this means that the bitmap was set up for the GCLab
1848 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant");
1849
1850 mark_bitmap->mostly_disjoint_range_union(this,
1851 0, // always start from the start of the bitmap
1852 _start_word,
1853 gclab_real_word_size());
1854 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word));
1855
1856 #ifndef PRODUCT
1857 if (use_local_bitmaps && verify_local_bitmaps)
1858 verify();
1859 #endif // PRODUCT
1860 } else {
1861 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant");
1862 }
1863 }
1864
1865 size_t bitmap_size_in_words() const {
1866 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord;
1867 }
1868
1869 };
1870
1871 class G1ParGCAllocBuffer: public ParGCAllocBuffer {
1872 private:
1873 bool _retired;
1874
1875 public:
1876 G1ParGCAllocBuffer(size_t gclab_word_size);
1877
1878 void set_buf(HeapWord* buf) {
1879 ParGCAllocBuffer::set_buf(buf);
1880 _retired = false;
1881 }
1882
1883 void retire(bool end_of_gc, bool retain) {
1884 if (_retired)
1885 return;
1886 ParGCAllocBuffer::retire(end_of_gc, retain);
1887 _retired = true;
1888 }
1889 };
1890
1891 class G1ParScanThreadState : public StackObj {
1892 protected:
1893 G1CollectedHeap* _g1h;
1894 RefToScanQueue* _refs;
1895 DirtyCardQueue _dcq;
1896 CardTableModRefBS* _ct_bs;
1897 G1RemSet* _g1_rem;
1898
1899 G1ParGCAllocBuffer _surviving_alloc_buffer;
1900 G1ParGCAllocBuffer _tenured_alloc_buffer;
1901 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount];
1902 ageTable _age_table;
1903
1904 size_t _alloc_buffer_waste;
1905 size_t _undo_waste;
1906
1907 OopsInHeapRegionClosure* _evac_failure_cl;
1908 G1ParScanHeapEvacClosure* _evac_cl;
1909 G1ParScanPartialArrayClosure* _partial_scan_cl;
1910
1911 int _hash_seed;
1912 uint _queue_num;
1913
1914 size_t _term_attempts;
1915
1916 double _start;
1917 double _start_strong_roots;
1918 double _strong_roots_time;
1919 double _start_term;
1920 double _term_time;
1921
1922 // Map from young-age-index (0 == not young, 1 is youngest) to
1923 // surviving words. base is what we get back from the malloc call
1924 size_t* _surviving_young_words_base;
1925 // this points into the array, as we use the first few entries for padding
1926 size_t* _surviving_young_words;
1927
1928 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t))
1929
1930 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
1931
1932 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
1933
1934 DirtyCardQueue& dirty_card_queue() { return _dcq; }
1935 CardTableModRefBS* ctbs() { return _ct_bs; }
1936
1937 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) {
1938 if (!from->is_survivor()) {
1939 _g1_rem->par_write_ref(from, p, tid);
1940 }
1941 }
1942
1943 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
1944 // If the new value of the field points to the same region or
1945 // is the to-space, we don't need to include it in the Rset updates.
1946 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
1947 size_t card_index = ctbs()->index_for(p);
1948 // If the card hasn't been added to the buffer, do it.
1949 if (ctbs()->mark_card_deferred(card_index)) {
1950 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
1951 }
1952 }
1953 }
1954
1955 public:
1956 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
1957
1958 ~G1ParScanThreadState() {
1959 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
1960 }
1961
1962 RefToScanQueue* refs() { return _refs; }
1963 ageTable* age_table() { return &_age_table; }
1964
1965 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) {
1966 return _alloc_buffers[purpose];
1967 }
1968
1969 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; }
1970 size_t undo_waste() const { return _undo_waste; }
1971
1972 #ifdef ASSERT
1973 bool verify_ref(narrowOop* ref) const;
1974 bool verify_ref(oop* ref) const;
1975 bool verify_task(StarTask ref) const;
1976 #endif // ASSERT
1977
1978 template <class T> void push_on_queue(T* ref) {
1979 assert(verify_ref(ref), "sanity");
1980 refs()->push(ref);
1981 }
1982
1983 template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
1984 if (G1DeferredRSUpdate) {
1985 deferred_rs_update(from, p, tid);
1986 } else {
1987 immediate_rs_update(from, p, tid);
1988 }
1989 }
1990
1991 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) {
1992
1993 HeapWord* obj = NULL;
1994 size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
1995 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
1996 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);
1997 assert(gclab_word_size == alloc_buf->word_sz(),
1998 "dynamic resizing is not supported");
1999 add_to_alloc_buffer_waste(alloc_buf->words_remaining());
2000 alloc_buf->retire(false, false);
2001
2002 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);
2003 if (buf == NULL) return NULL; // Let caller handle allocation failure.
2004 // Otherwise.
2005 alloc_buf->set_buf(buf);
2006
2007 obj = alloc_buf->allocate(word_sz);
2008 assert(obj != NULL, "buffer was definitely big enough...");
2009 } else {
2010 obj = _g1h->par_allocate_during_gc(purpose, word_sz);
2011 }
2012 return obj;
2013 }
2014
2015 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) {
2016 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz);
2017 if (obj != NULL) return obj;
2018 return allocate_slow(purpose, word_sz);
2019 }
2020
2021 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {
2022 if (alloc_buffer(purpose)->contains(obj)) {
2023 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),
2024 "should contain whole object");
2025 alloc_buffer(purpose)->undo_allocation(obj, word_sz);
2026 } else {
2027 CollectedHeap::fill_with_object(obj, word_sz);
2028 add_to_undo_waste(word_sz);
2029 }
2030 }
2031
2032 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) {
2033 _evac_failure_cl = evac_failure_cl;
2034 }
2035 OopsInHeapRegionClosure* evac_failure_closure() {
2036 return _evac_failure_cl;
2037 }
2038
2039 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) {
2040 _evac_cl = evac_cl;
2041 }
2042
2043 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) {
2044 _partial_scan_cl = partial_scan_cl;
2045 }
2046
2047 int* hash_seed() { return &_hash_seed; }
2048 uint queue_num() { return _queue_num; }
2049
2050 size_t term_attempts() const { return _term_attempts; }
2051 void note_term_attempt() { _term_attempts++; }
2052
2053 void start_strong_roots() {
2054 _start_strong_roots = os::elapsedTime();
2055 }
2056 void end_strong_roots() {
2057 _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
2058 }
2059 double strong_roots_time() const { return _strong_roots_time; }
2060
2061 void start_term_time() {
2062 note_term_attempt();
2063 _start_term = os::elapsedTime();
2064 }
2065 void end_term_time() {
2066 _term_time += (os::elapsedTime() - _start_term);
2067 }
2068 double term_time() const { return _term_time; }
2069
2070 double elapsed_time() const {
2071 return os::elapsedTime() - _start;
2072 }
2073
2074 static void
2075 print_termination_stats_hdr(outputStream* const st = gclog_or_tty);
2076 void
2077 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const;
2078
2079 size_t* surviving_young_words() {
2080 // We add on to hide entry 0 which accumulates surviving words for
2081 // age -1 regions (i.e. non-young ones)
2082 return _surviving_young_words;
2083 }
2084
2085 void retire_alloc_buffers() {
2086 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
2087 size_t waste = _alloc_buffers[ap]->words_remaining();
2088 add_to_alloc_buffer_waste(waste);
2089 _alloc_buffers[ap]->retire(true, false);
2090 }
2091 }
2092
2093 template <class T> void deal_with_reference(T* ref_to_scan) {
2094 if (has_partial_array_mask(ref_to_scan)) {
2095 _partial_scan_cl->do_oop_nv(ref_to_scan);
2096 } else {
2097 // Note: we can use "raw" versions of "region_containing" because
2098 // "obj_to_scan" is definitely in the heap, and is not in a
2099 // humongous region.
2100 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan);
2101 _evac_cl->set_region(r);
2102 _evac_cl->do_oop_nv(ref_to_scan);
2103 }
2104 }
2105
2106 void deal_with_reference(StarTask ref) {
2107 assert(verify_task(ref), "sanity");
2108 if (ref.is_narrow()) {
2109 deal_with_reference((narrowOop*)ref);
2110 } else {
2111 deal_with_reference((oop*)ref);
2112 }
2113 }
2114
2115 public:
2116 void trim_queue();
2117 };
2118
2119 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP