1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1MarkSweep.hpp"
46 #include "gc/g1/g1OopClosures.inline.hpp"
47 #include "gc/g1/g1ParScanThreadState.inline.hpp"
48 #include "gc/g1/g1RegionToSpaceMapper.hpp"
49 #include "gc/g1/g1RemSet.inline.hpp"
50 #include "gc/g1/g1RootClosures.hpp"
51 #include "gc/g1/g1RootProcessor.hpp"
52 #include "gc/g1/g1StringDedup.hpp"
53 #include "gc/g1/g1YCTypes.hpp"
54 #include "gc/g1/heapRegion.inline.hpp"
55 #include "gc/g1/heapRegionRemSet.hpp"
56 #include "gc/g1/heapRegionSet.inline.hpp"
57 #include "gc/g1/suspendibleThreadSet.hpp"
58 #include "gc/g1/vm_operations_g1.hpp"
59 #include "gc/shared/gcHeapSummary.hpp"
60 #include "gc/shared/gcId.hpp"
61 #include "gc/shared/gcLocker.inline.hpp"
62 #include "gc/shared/gcTimer.hpp"
63 #include "gc/shared/gcTrace.hpp"
64 #include "gc/shared/gcTraceTime.inline.hpp"
65 #include "gc/shared/generationSpec.hpp"
66 #include "gc/shared/isGCActiveMark.hpp"
67 #include "gc/shared/referenceProcessor.inline.hpp"
68 #include "gc/shared/taskqueue.inline.hpp"
69 #include "logging/log.hpp"
70 #include "memory/allocation.hpp"
71 #include "memory/iterator.hpp"
72 #include "memory/resourceArea.hpp"
73 #include "oops/oop.inline.hpp"
74 #include "runtime/atomic.inline.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/orderAccess.inline.hpp"
77 #include "runtime/vmThread.hpp"
78 #include "utilities/globalDefinitions.hpp"
79 #include "utilities/stack.inline.hpp"
80
81 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_dirtied;
121 G1CollectedHeap* _g1h;
122 G1SATBCardTableLoggingModRefBS* _g1_bs;
123
124 HeapRegion* region_for_card(jbyte* card_ptr) const {
125 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
126 }
127
128 bool will_become_free(HeapRegion* hr) const {
129 // A region will be freed by free_collection_set if the region is in the
130 // collection set and has not had an evacuation failure.
131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
132 }
133
134 public:
135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
136 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
137
138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
139 HeapRegion* hr = region_for_card(card_ptr);
140
141 // Should only dirty cards in regions that won't be freed.
142 if (!will_become_free(hr)) {
143 *card_ptr = CardTableModRefBS::dirty_card_val();
144 _num_dirtied++;
145 }
146
147 return true;
148 }
149
150 size_t num_dirtied() const { return _num_dirtied; }
151 };
152
153
154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
156 }
157
158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
159 // The from card cache is not the memory that is actually committed. So we cannot
160 // take advantage of the zero_filled parameter.
161 reset_from_card_cache(start_idx, num_regions);
162 }
163
164 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
165 {
166 // Claim the right to put the region on the dirty cards region list
167 // by installing a self pointer.
168 HeapRegion* next = hr->get_next_dirty_cards_region();
169 if (next == NULL) {
170 HeapRegion* res = (HeapRegion*)
171 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
172 NULL);
173 if (res == NULL) {
174 HeapRegion* head;
175 do {
176 // Put the region to the dirty cards region list.
177 head = _dirty_cards_region_list;
178 next = (HeapRegion*)
179 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
180 if (next == head) {
181 assert(hr->get_next_dirty_cards_region() == hr,
182 "hr->get_next_dirty_cards_region() != hr");
183 if (next == NULL) {
184 // The last region in the list points to itself.
185 hr->set_next_dirty_cards_region(hr);
186 } else {
187 hr->set_next_dirty_cards_region(next);
188 }
189 }
190 } while (next != head);
191 }
192 }
193 }
194
195 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
196 {
197 HeapRegion* head;
198 HeapRegion* hr;
199 do {
200 head = _dirty_cards_region_list;
201 if (head == NULL) {
202 return NULL;
203 }
204 HeapRegion* new_head = head->get_next_dirty_cards_region();
205 if (head == new_head) {
206 // The last region.
207 new_head = NULL;
208 }
209 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
210 head);
211 } while (hr != head);
212 assert(hr != NULL, "invariant");
213 hr->set_next_dirty_cards_region(NULL);
214 return hr;
215 }
216
217 // Returns true if the reference points to an object that
218 // can move in an incremental collection.
219 bool G1CollectedHeap::is_scavengable(const void* p) {
220 HeapRegion* hr = heap_region_containing(p);
221 return !hr->is_pinned();
222 }
223
224 // Private methods.
225
226 HeapRegion*
227 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
228 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
229 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
230 if (!_secondary_free_list.is_empty()) {
231 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
232 "secondary_free_list has %u entries",
233 _secondary_free_list.length());
234 // It looks as if there are free regions available on the
235 // secondary_free_list. Let's move them to the free_list and try
236 // again to allocate from it.
237 append_secondary_free_list();
238
239 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
240 "empty we should have moved at least one entry to the free_list");
241 HeapRegion* res = _hrm.allocate_free_region(is_old);
242 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
243 "allocated " HR_FORMAT " from secondary_free_list",
244 HR_FORMAT_PARAMS(res));
245 return res;
246 }
247
248 // Wait here until we get notified either when (a) there are no
249 // more free regions coming or (b) some regions have been moved on
250 // the secondary_free_list.
251 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
252 }
253
254 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
255 "could not allocate from secondary_free_list");
256 return NULL;
257 }
258
259 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
260 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
261 "the only time we use this to allocate a humongous region is "
262 "when we are allocating a single humongous region");
263
264 HeapRegion* res;
265 if (G1StressConcRegionFreeing) {
266 if (!_secondary_free_list.is_empty()) {
267 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
268 "forced to look at the secondary_free_list");
269 res = new_region_try_secondary_free_list(is_old);
270 if (res != NULL) {
271 return res;
272 }
273 }
274 }
275
276 res = _hrm.allocate_free_region(is_old);
277
278 if (res == NULL) {
279 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
280 "res == NULL, trying the secondary_free_list");
281 res = new_region_try_secondary_free_list(is_old);
282 }
283 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
284 // Currently, only attempts to allocate GC alloc regions set
285 // do_expand to true. So, we should only reach here during a
286 // safepoint. If this assumption changes we might have to
287 // reconsider the use of _expand_heap_after_alloc_failure.
288 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
289
290 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
291 word_size * HeapWordSize);
292
293 if (expand(word_size * HeapWordSize)) {
294 // Given that expand() succeeded in expanding the heap, and we
295 // always expand the heap by an amount aligned to the heap
296 // region size, the free list should in theory not be empty.
297 // In either case allocate_free_region() will check for NULL.
298 res = _hrm.allocate_free_region(is_old);
299 } else {
300 _expand_heap_after_alloc_failure = false;
301 }
302 }
303 return res;
304 }
305
306 HeapWord*
307 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
308 uint num_regions,
309 size_t word_size,
310 AllocationContext_t context) {
311 assert(first != G1_NO_HRM_INDEX, "pre-condition");
312 assert(is_humongous(word_size), "word_size should be humongous");
313 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
314
315 // Index of last region in the series.
316 uint last = first + num_regions - 1;
317
318 // We need to initialize the region(s) we just discovered. This is
319 // a bit tricky given that it can happen concurrently with
320 // refinement threads refining cards on these regions and
321 // potentially wanting to refine the BOT as they are scanning
322 // those cards (this can happen shortly after a cleanup; see CR
323 // 6991377). So we have to set up the region(s) carefully and in
324 // a specific order.
325
326 // The word size sum of all the regions we will allocate.
327 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
328 assert(word_size <= word_size_sum, "sanity");
329
330 // This will be the "starts humongous" region.
331 HeapRegion* first_hr = region_at(first);
332 // The header of the new object will be placed at the bottom of
333 // the first region.
334 HeapWord* new_obj = first_hr->bottom();
335 // This will be the new top of the new object.
336 HeapWord* obj_top = new_obj + word_size;
337
338 // First, we need to zero the header of the space that we will be
339 // allocating. When we update top further down, some refinement
340 // threads might try to scan the region. By zeroing the header we
341 // ensure that any thread that will try to scan the region will
342 // come across the zero klass word and bail out.
343 //
344 // NOTE: It would not have been correct to have used
345 // CollectedHeap::fill_with_object() and make the space look like
346 // an int array. The thread that is doing the allocation will
347 // later update the object header to a potentially different array
348 // type and, for a very short period of time, the klass and length
349 // fields will be inconsistent. This could cause a refinement
350 // thread to calculate the object size incorrectly.
351 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
352
353 // How many words we use for filler objects.
354 size_t word_fill_size = word_size_sum - word_size;
355
356 // How many words memory we "waste" which cannot hold a filler object.
357 size_t words_not_fillable = 0;
358
359 if (word_fill_size >= min_fill_size()) {
360 fill_with_objects(obj_top, word_fill_size);
361 } else if (word_fill_size > 0) {
362 // We have space to fill, but we cannot fit an object there.
363 words_not_fillable = word_fill_size;
364 word_fill_size = 0;
365 }
366
367 // We will set up the first region as "starts humongous". This
368 // will also update the BOT covering all the regions to reflect
369 // that there is a single object that starts at the bottom of the
370 // first region.
371 first_hr->set_starts_humongous(obj_top, word_fill_size);
372 first_hr->set_allocation_context(context);
373 // Then, if there are any, we will set up the "continues
374 // humongous" regions.
375 HeapRegion* hr = NULL;
376 for (uint i = first + 1; i <= last; ++i) {
377 hr = region_at(i);
378 hr->set_continues_humongous(first_hr);
379 hr->set_allocation_context(context);
380 }
381
382 // Up to this point no concurrent thread would have been able to
383 // do any scanning on any region in this series. All the top
384 // fields still point to bottom, so the intersection between
385 // [bottom,top] and [card_start,card_end] will be empty. Before we
386 // update the top fields, we'll do a storestore to make sure that
387 // no thread sees the update to top before the zeroing of the
388 // object header and the BOT initialization.
389 OrderAccess::storestore();
390
391 // Now, we will update the top fields of the "continues humongous"
392 // regions except the last one.
393 for (uint i = first; i < last; ++i) {
394 hr = region_at(i);
395 hr->set_top(hr->end());
396 }
397
398 hr = region_at(last);
399 // If we cannot fit a filler object, we must set top to the end
400 // of the humongous object, otherwise we cannot iterate the heap
401 // and the BOT will not be complete.
402 hr->set_top(hr->end() - words_not_fillable);
403
404 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
405 "obj_top should be in last region");
406
407 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
408
409 assert(words_not_fillable == 0 ||
410 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
411 "Miscalculation in humongous allocation");
412
413 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
414
415 for (uint i = first; i <= last; ++i) {
416 hr = region_at(i);
417 _humongous_set.add(hr);
418 _hr_printer.alloc(hr);
419 }
420
421 return new_obj;
422 }
423
424 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
425 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
426 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
427 }
428
429 // If could fit into free regions w/o expansion, try.
430 // Otherwise, if can expand, do so.
431 // Otherwise, if using ex regions might help, try with ex given back.
432 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
433 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
434
435 _verifier->verify_region_sets_optional();
436
437 uint first = G1_NO_HRM_INDEX;
438 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
439
440 if (obj_regions == 1) {
441 // Only one region to allocate, try to use a fast path by directly allocating
442 // from the free lists. Do not try to expand here, we will potentially do that
443 // later.
444 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
445 if (hr != NULL) {
446 first = hr->hrm_index();
447 }
448 } else {
449 // We can't allocate humongous regions spanning more than one region while
450 // cleanupComplete() is running, since some of the regions we find to be
451 // empty might not yet be added to the free list. It is not straightforward
452 // to know in which list they are on so that we can remove them. We only
453 // need to do this if we need to allocate more than one region to satisfy the
454 // current humongous allocation request. If we are only allocating one region
455 // we use the one-region region allocation code (see above), that already
456 // potentially waits for regions from the secondary free list.
457 wait_while_free_regions_coming();
458 append_secondary_free_list_if_not_empty_with_lock();
459
460 // Policy: Try only empty regions (i.e. already committed first). Maybe we
461 // are lucky enough to find some.
462 first = _hrm.find_contiguous_only_empty(obj_regions);
463 if (first != G1_NO_HRM_INDEX) {
464 _hrm.allocate_free_regions_starting_at(first, obj_regions);
465 }
466 }
467
468 if (first == G1_NO_HRM_INDEX) {
469 // Policy: We could not find enough regions for the humongous object in the
470 // free list. Look through the heap to find a mix of free and uncommitted regions.
471 // If so, try expansion.
472 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
473 if (first != G1_NO_HRM_INDEX) {
474 // We found something. Make sure these regions are committed, i.e. expand
475 // the heap. Alternatively we could do a defragmentation GC.
476 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
477 word_size * HeapWordSize);
478
479
480 _hrm.expand_at(first, obj_regions);
481 g1_policy()->record_new_heap_size(num_regions());
482
483 #ifdef ASSERT
484 for (uint i = first; i < first + obj_regions; ++i) {
485 HeapRegion* hr = region_at(i);
486 assert(hr->is_free(), "sanity");
487 assert(hr->is_empty(), "sanity");
488 assert(is_on_master_free_list(hr), "sanity");
489 }
490 #endif
491 _hrm.allocate_free_regions_starting_at(first, obj_regions);
492 } else {
493 // Policy: Potentially trigger a defragmentation GC.
494 }
495 }
496
497 HeapWord* result = NULL;
498 if (first != G1_NO_HRM_INDEX) {
499 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
500 word_size, context);
501 assert(result != NULL, "it should always return a valid result");
502
503 // A successful humongous object allocation changes the used space
504 // information of the old generation so we need to recalculate the
505 // sizes and update the jstat counters here.
506 g1mm()->update_sizes();
507 }
508
509 _verifier->verify_region_sets_optional();
510
511 return result;
512 }
513
514 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
515 assert_heap_not_locked_and_not_at_safepoint();
516 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
517
518 uint dummy_gc_count_before;
519 uint dummy_gclocker_retry_count = 0;
520 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
521 }
522
523 HeapWord*
524 G1CollectedHeap::mem_allocate(size_t word_size,
525 bool* gc_overhead_limit_was_exceeded) {
526 assert_heap_not_locked_and_not_at_safepoint();
527
528 // Loop until the allocation is satisfied, or unsatisfied after GC.
529 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
530 uint gc_count_before;
531
532 HeapWord* result = NULL;
533 if (!is_humongous(word_size)) {
534 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
535 } else {
536 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
537 }
538 if (result != NULL) {
539 return result;
540 }
541
542 // Create the garbage collection operation...
543 VM_G1CollectForAllocation op(gc_count_before, word_size);
544 op.set_allocation_context(AllocationContext::current());
545
546 // ...and get the VM thread to execute it.
547 VMThread::execute(&op);
548
549 if (op.prologue_succeeded() && op.pause_succeeded()) {
550 // If the operation was successful we'll return the result even
551 // if it is NULL. If the allocation attempt failed immediately
552 // after a Full GC, it's unlikely we'll be able to allocate now.
553 HeapWord* result = op.result();
554 if (result != NULL && !is_humongous(word_size)) {
555 // Allocations that take place on VM operations do not do any
556 // card dirtying and we have to do it here. We only have to do
557 // this for non-humongous allocations, though.
558 dirty_young_block(result, word_size);
559 }
560 return result;
561 } else {
562 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
563 return NULL;
564 }
565 assert(op.result() == NULL,
566 "the result should be NULL if the VM op did not succeed");
567 }
568
569 // Give a warning if we seem to be looping forever.
570 if ((QueuedAllocationWarningCount > 0) &&
571 (try_count % QueuedAllocationWarningCount == 0)) {
572 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
573 }
574 }
575
576 ShouldNotReachHere();
577 return NULL;
578 }
579
580 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
581 AllocationContext_t context,
582 uint* gc_count_before_ret,
583 uint* gclocker_retry_count_ret) {
584 // Make sure you read the note in attempt_allocation_humongous().
585
586 assert_heap_not_locked_and_not_at_safepoint();
587 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
588 "be called for humongous allocation requests");
589
590 // We should only get here after the first-level allocation attempt
591 // (attempt_allocation()) failed to allocate.
592
593 // We will loop until a) we manage to successfully perform the
594 // allocation or b) we successfully schedule a collection which
595 // fails to perform the allocation. b) is the only case when we'll
596 // return NULL.
597 HeapWord* result = NULL;
598 for (int try_count = 1; /* we'll return */; try_count += 1) {
599 bool should_try_gc;
600 uint gc_count_before;
601
602 {
603 MutexLockerEx x(Heap_lock);
604 result = _allocator->attempt_allocation_locked(word_size, context);
605 if (result != NULL) {
606 return result;
607 }
608
609 if (GCLocker::is_active_and_needs_gc()) {
610 if (g1_policy()->can_expand_young_list()) {
611 // No need for an ergo verbose message here,
612 // can_expand_young_list() does this when it returns true.
613 result = _allocator->attempt_allocation_force(word_size, context);
614 if (result != NULL) {
615 return result;
616 }
617 }
618 should_try_gc = false;
619 } else {
620 // The GCLocker may not be active but the GCLocker initiated
621 // GC may not yet have been performed (GCLocker::needs_gc()
622 // returns true). In this case we do not try this GC and
623 // wait until the GCLocker initiated GC is performed, and
624 // then retry the allocation.
625 if (GCLocker::needs_gc()) {
626 should_try_gc = false;
627 } else {
628 // Read the GC count while still holding the Heap_lock.
629 gc_count_before = total_collections();
630 should_try_gc = true;
631 }
632 }
633 }
634
635 if (should_try_gc) {
636 bool succeeded;
637 result = do_collection_pause(word_size, gc_count_before, &succeeded,
638 GCCause::_g1_inc_collection_pause);
639 if (result != NULL) {
640 assert(succeeded, "only way to get back a non-NULL result");
641 return result;
642 }
643
644 if (succeeded) {
645 // If we get here we successfully scheduled a collection which
646 // failed to allocate. No point in trying to allocate
647 // further. We'll just return NULL.
648 MutexLockerEx x(Heap_lock);
649 *gc_count_before_ret = total_collections();
650 return NULL;
651 }
652 } else {
653 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
654 MutexLockerEx x(Heap_lock);
655 *gc_count_before_ret = total_collections();
656 return NULL;
657 }
658 // The GCLocker is either active or the GCLocker initiated
659 // GC has not yet been performed. Stall until it is and
660 // then retry the allocation.
661 GCLocker::stall_until_clear();
662 (*gclocker_retry_count_ret) += 1;
663 }
664
665 // We can reach here if we were unsuccessful in scheduling a
666 // collection (because another thread beat us to it) or if we were
667 // stalled due to the GC locker. In either can we should retry the
668 // allocation attempt in case another thread successfully
669 // performed a collection and reclaimed enough space. We do the
670 // first attempt (without holding the Heap_lock) here and the
671 // follow-on attempt will be at the start of the next loop
672 // iteration (after taking the Heap_lock).
673 result = _allocator->attempt_allocation(word_size, context);
674 if (result != NULL) {
675 return result;
676 }
677
678 // Give a warning if we seem to be looping forever.
679 if ((QueuedAllocationWarningCount > 0) &&
680 (try_count % QueuedAllocationWarningCount == 0)) {
681 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
682 "retries %d times", try_count);
683 }
684 }
685
686 ShouldNotReachHere();
687 return NULL;
688 }
689
690 void G1CollectedHeap::begin_archive_alloc_range() {
691 assert_at_safepoint(true /* should_be_vm_thread */);
692 if (_archive_allocator == NULL) {
693 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
694 }
695 }
696
697 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
698 // Allocations in archive regions cannot be of a size that would be considered
699 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
700 // may be different at archive-restore time.
701 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
702 }
703
704 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
705 assert_at_safepoint(true /* should_be_vm_thread */);
706 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
707 if (is_archive_alloc_too_large(word_size)) {
708 return NULL;
709 }
710 return _archive_allocator->archive_mem_allocate(word_size);
711 }
712
713 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
714 size_t end_alignment_in_bytes) {
715 assert_at_safepoint(true /* should_be_vm_thread */);
716 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
717
718 // Call complete_archive to do the real work, filling in the MemRegion
719 // array with the archive regions.
720 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
721 delete _archive_allocator;
722 _archive_allocator = NULL;
723 }
724
725 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
726 assert(ranges != NULL, "MemRegion array NULL");
727 assert(count != 0, "No MemRegions provided");
728 MemRegion reserved = _hrm.reserved();
729 for (size_t i = 0; i < count; i++) {
730 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
731 return false;
732 }
733 }
734 return true;
735 }
736
737 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
738 assert(!is_init_completed(), "Expect to be called at JVM init time");
739 assert(ranges != NULL, "MemRegion array NULL");
740 assert(count != 0, "No MemRegions provided");
741 MutexLockerEx x(Heap_lock);
742
743 MemRegion reserved = _hrm.reserved();
744 HeapWord* prev_last_addr = NULL;
745 HeapRegion* prev_last_region = NULL;
746
747 // Temporarily disable pretouching of heap pages. This interface is used
748 // when mmap'ing archived heap data in, so pre-touching is wasted.
749 FlagSetting fs(AlwaysPreTouch, false);
750
751 // Enable archive object checking in G1MarkSweep. We have to let it know
752 // about each archive range, so that objects in those ranges aren't marked.
753 G1MarkSweep::enable_archive_object_check();
754
755 // For each specified MemRegion range, allocate the corresponding G1
756 // regions and mark them as archive regions. We expect the ranges in
757 // ascending starting address order, without overlap.
758 for (size_t i = 0; i < count; i++) {
759 MemRegion curr_range = ranges[i];
760 HeapWord* start_address = curr_range.start();
761 size_t word_size = curr_range.word_size();
762 HeapWord* last_address = curr_range.last();
763 size_t commits = 0;
764
765 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
766 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
767 p2i(start_address), p2i(last_address));
768 guarantee(start_address > prev_last_addr,
769 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
770 p2i(start_address), p2i(prev_last_addr));
771 prev_last_addr = last_address;
772
773 // Check for ranges that start in the same G1 region in which the previous
774 // range ended, and adjust the start address so we don't try to allocate
775 // the same region again. If the current range is entirely within that
776 // region, skip it, just adjusting the recorded top.
777 HeapRegion* start_region = _hrm.addr_to_region(start_address);
778 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
779 start_address = start_region->end();
780 if (start_address > last_address) {
781 increase_used(word_size * HeapWordSize);
782 start_region->set_top(last_address + 1);
783 continue;
784 }
785 start_region->set_top(start_address);
786 curr_range = MemRegion(start_address, last_address + 1);
787 start_region = _hrm.addr_to_region(start_address);
788 }
789
790 // Perform the actual region allocation, exiting if it fails.
791 // Then note how much new space we have allocated.
792 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
793 return false;
794 }
795 increase_used(word_size * HeapWordSize);
796 if (commits != 0) {
797 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
798 HeapRegion::GrainWords * HeapWordSize * commits);
799
800 }
801
802 // Mark each G1 region touched by the range as archive, add it to the old set,
803 // and set the allocation context and top.
804 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
805 HeapRegion* last_region = _hrm.addr_to_region(last_address);
806 prev_last_region = last_region;
807
808 while (curr_region != NULL) {
809 assert(curr_region->is_empty() && !curr_region->is_pinned(),
810 "Region already in use (index %u)", curr_region->hrm_index());
811 curr_region->set_allocation_context(AllocationContext::system());
812 curr_region->set_archive();
813 _hr_printer.alloc(curr_region);
814 _old_set.add(curr_region);
815 if (curr_region != last_region) {
816 curr_region->set_top(curr_region->end());
817 curr_region = _hrm.next_region_in_heap(curr_region);
818 } else {
819 curr_region->set_top(last_address + 1);
820 curr_region = NULL;
821 }
822 }
823
824 // Notify mark-sweep of the archive range.
825 G1MarkSweep::set_range_archive(curr_range, true);
826 }
827 return true;
828 }
829
830 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
831 assert(!is_init_completed(), "Expect to be called at JVM init time");
832 assert(ranges != NULL, "MemRegion array NULL");
833 assert(count != 0, "No MemRegions provided");
834 MemRegion reserved = _hrm.reserved();
835 HeapWord *prev_last_addr = NULL;
836 HeapRegion* prev_last_region = NULL;
837
838 // For each MemRegion, create filler objects, if needed, in the G1 regions
839 // that contain the address range. The address range actually within the
840 // MemRegion will not be modified. That is assumed to have been initialized
841 // elsewhere, probably via an mmap of archived heap data.
842 MutexLockerEx x(Heap_lock);
843 for (size_t i = 0; i < count; i++) {
844 HeapWord* start_address = ranges[i].start();
845 HeapWord* last_address = ranges[i].last();
846
847 assert(reserved.contains(start_address) && reserved.contains(last_address),
848 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
849 p2i(start_address), p2i(last_address));
850 assert(start_address > prev_last_addr,
851 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
852 p2i(start_address), p2i(prev_last_addr));
853
854 HeapRegion* start_region = _hrm.addr_to_region(start_address);
855 HeapRegion* last_region = _hrm.addr_to_region(last_address);
856 HeapWord* bottom_address = start_region->bottom();
857
858 // Check for a range beginning in the same region in which the
859 // previous one ended.
860 if (start_region == prev_last_region) {
861 bottom_address = prev_last_addr + 1;
862 }
863
864 // Verify that the regions were all marked as archive regions by
865 // alloc_archive_regions.
866 HeapRegion* curr_region = start_region;
867 while (curr_region != NULL) {
868 guarantee(curr_region->is_archive(),
869 "Expected archive region at index %u", curr_region->hrm_index());
870 if (curr_region != last_region) {
871 curr_region = _hrm.next_region_in_heap(curr_region);
872 } else {
873 curr_region = NULL;
874 }
875 }
876
877 prev_last_addr = last_address;
878 prev_last_region = last_region;
879
880 // Fill the memory below the allocated range with dummy object(s),
881 // if the region bottom does not match the range start, or if the previous
882 // range ended within the same G1 region, and there is a gap.
883 if (start_address != bottom_address) {
884 size_t fill_size = pointer_delta(start_address, bottom_address);
885 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
886 increase_used(fill_size * HeapWordSize);
887 }
888 }
889 }
890
891 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
892 uint* gc_count_before_ret,
893 uint* gclocker_retry_count_ret) {
894 assert_heap_not_locked_and_not_at_safepoint();
895 assert(!is_humongous(word_size), "attempt_allocation() should not "
896 "be called for humongous allocation requests");
897
898 AllocationContext_t context = AllocationContext::current();
899 HeapWord* result = _allocator->attempt_allocation(word_size, context);
900
901 if (result == NULL) {
902 result = attempt_allocation_slow(word_size,
903 context,
904 gc_count_before_ret,
905 gclocker_retry_count_ret);
906 }
907 assert_heap_not_locked();
908 if (result != NULL) {
909 dirty_young_block(result, word_size);
910 }
911 return result;
912 }
913
914 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
915 assert(!is_init_completed(), "Expect to be called at JVM init time");
916 assert(ranges != NULL, "MemRegion array NULL");
917 assert(count != 0, "No MemRegions provided");
918 MemRegion reserved = _hrm.reserved();
919 HeapWord* prev_last_addr = NULL;
920 HeapRegion* prev_last_region = NULL;
921 size_t size_used = 0;
922 size_t uncommitted_regions = 0;
923
924 // For each Memregion, free the G1 regions that constitute it, and
925 // notify mark-sweep that the range is no longer to be considered 'archive.'
926 MutexLockerEx x(Heap_lock);
927 for (size_t i = 0; i < count; i++) {
928 HeapWord* start_address = ranges[i].start();
929 HeapWord* last_address = ranges[i].last();
930
931 assert(reserved.contains(start_address) && reserved.contains(last_address),
932 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
933 p2i(start_address), p2i(last_address));
934 assert(start_address > prev_last_addr,
935 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
936 p2i(start_address), p2i(prev_last_addr));
937 size_used += ranges[i].byte_size();
938 prev_last_addr = last_address;
939
940 HeapRegion* start_region = _hrm.addr_to_region(start_address);
941 HeapRegion* last_region = _hrm.addr_to_region(last_address);
942
943 // Check for ranges that start in the same G1 region in which the previous
944 // range ended, and adjust the start address so we don't try to free
945 // the same region again. If the current range is entirely within that
946 // region, skip it.
947 if (start_region == prev_last_region) {
948 start_address = start_region->end();
949 if (start_address > last_address) {
950 continue;
951 }
952 start_region = _hrm.addr_to_region(start_address);
953 }
954 prev_last_region = last_region;
955
956 // After verifying that each region was marked as an archive region by
957 // alloc_archive_regions, set it free and empty and uncommit it.
958 HeapRegion* curr_region = start_region;
959 while (curr_region != NULL) {
960 guarantee(curr_region->is_archive(),
961 "Expected archive region at index %u", curr_region->hrm_index());
962 uint curr_index = curr_region->hrm_index();
963 _old_set.remove(curr_region);
964 curr_region->set_free();
965 curr_region->set_top(curr_region->bottom());
966 if (curr_region != last_region) {
967 curr_region = _hrm.next_region_in_heap(curr_region);
968 } else {
969 curr_region = NULL;
970 }
971 _hrm.shrink_at(curr_index, 1);
972 uncommitted_regions++;
973 }
974
975 // Notify mark-sweep that this is no longer an archive range.
976 G1MarkSweep::set_range_archive(ranges[i], false);
977 }
978
979 if (uncommitted_regions != 0) {
980 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
981 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
982 }
983 decrease_used(size_used);
984 }
985
986 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
987 uint* gc_count_before_ret,
988 uint* gclocker_retry_count_ret) {
989 // The structure of this method has a lot of similarities to
990 // attempt_allocation_slow(). The reason these two were not merged
991 // into a single one is that such a method would require several "if
992 // allocation is not humongous do this, otherwise do that"
993 // conditional paths which would obscure its flow. In fact, an early
994 // version of this code did use a unified method which was harder to
995 // follow and, as a result, it had subtle bugs that were hard to
996 // track down. So keeping these two methods separate allows each to
997 // be more readable. It will be good to keep these two in sync as
998 // much as possible.
999
1000 assert_heap_not_locked_and_not_at_safepoint();
1001 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1002 "should only be called for humongous allocations");
1003
1004 // Humongous objects can exhaust the heap quickly, so we should check if we
1005 // need to start a marking cycle at each humongous object allocation. We do
1006 // the check before we do the actual allocation. The reason for doing it
1007 // before the allocation is that we avoid having to keep track of the newly
1008 // allocated memory while we do a GC.
1009 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1010 word_size)) {
1011 collect(GCCause::_g1_humongous_allocation);
1012 }
1013
1014 // We will loop until a) we manage to successfully perform the
1015 // allocation or b) we successfully schedule a collection which
1016 // fails to perform the allocation. b) is the only case when we'll
1017 // return NULL.
1018 HeapWord* result = NULL;
1019 for (int try_count = 1; /* we'll return */; try_count += 1) {
1020 bool should_try_gc;
1021 uint gc_count_before;
1022
1023 {
1024 MutexLockerEx x(Heap_lock);
1025
1026 // Given that humongous objects are not allocated in young
1027 // regions, we'll first try to do the allocation without doing a
1028 // collection hoping that there's enough space in the heap.
1029 result = humongous_obj_allocate(word_size, AllocationContext::current());
1030 if (result != NULL) {
1031 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1032 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1033 return result;
1034 }
1035
1036 if (GCLocker::is_active_and_needs_gc()) {
1037 should_try_gc = false;
1038 } else {
1039 // The GCLocker may not be active but the GCLocker initiated
1040 // GC may not yet have been performed (GCLocker::needs_gc()
1041 // returns true). In this case we do not try this GC and
1042 // wait until the GCLocker initiated GC is performed, and
1043 // then retry the allocation.
1044 if (GCLocker::needs_gc()) {
1045 should_try_gc = false;
1046 } else {
1047 // Read the GC count while still holding the Heap_lock.
1048 gc_count_before = total_collections();
1049 should_try_gc = true;
1050 }
1051 }
1052 }
1053
1054 if (should_try_gc) {
1055 // If we failed to allocate the humongous object, we should try to
1056 // do a collection pause (if we're allowed) in case it reclaims
1057 // enough space for the allocation to succeed after the pause.
1058
1059 bool succeeded;
1060 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1061 GCCause::_g1_humongous_allocation);
1062 if (result != NULL) {
1063 assert(succeeded, "only way to get back a non-NULL result");
1064 return result;
1065 }
1066
1067 if (succeeded) {
1068 // If we get here we successfully scheduled a collection which
1069 // failed to allocate. No point in trying to allocate
1070 // further. We'll just return NULL.
1071 MutexLockerEx x(Heap_lock);
1072 *gc_count_before_ret = total_collections();
1073 return NULL;
1074 }
1075 } else {
1076 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1077 MutexLockerEx x(Heap_lock);
1078 *gc_count_before_ret = total_collections();
1079 return NULL;
1080 }
1081 // The GCLocker is either active or the GCLocker initiated
1082 // GC has not yet been performed. Stall until it is and
1083 // then retry the allocation.
1084 GCLocker::stall_until_clear();
1085 (*gclocker_retry_count_ret) += 1;
1086 }
1087
1088 // We can reach here if we were unsuccessful in scheduling a
1089 // collection (because another thread beat us to it) or if we were
1090 // stalled due to the GC locker. In either can we should retry the
1091 // allocation attempt in case another thread successfully
1092 // performed a collection and reclaimed enough space. Give a
1093 // warning if we seem to be looping forever.
1094
1095 if ((QueuedAllocationWarningCount > 0) &&
1096 (try_count % QueuedAllocationWarningCount == 0)) {
1097 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1098 "retries %d times", try_count);
1099 }
1100 }
1101
1102 ShouldNotReachHere();
1103 return NULL;
1104 }
1105
1106 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1107 AllocationContext_t context,
1108 bool expect_null_mutator_alloc_region) {
1109 assert_at_safepoint(true /* should_be_vm_thread */);
1110 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1111 "the current alloc region was unexpectedly found to be non-NULL");
1112
1113 if (!is_humongous(word_size)) {
1114 return _allocator->attempt_allocation_locked(word_size, context);
1115 } else {
1116 HeapWord* result = humongous_obj_allocate(word_size, context);
1117 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1118 collector_state()->set_initiate_conc_mark_if_possible(true);
1119 }
1120 return result;
1121 }
1122
1123 ShouldNotReachHere();
1124 }
1125
1126 class PostMCRemSetClearClosure: public HeapRegionClosure {
1127 G1CollectedHeap* _g1h;
1128 ModRefBarrierSet* _mr_bs;
1129 public:
1130 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1131 _g1h(g1h), _mr_bs(mr_bs) {}
1132
1133 bool doHeapRegion(HeapRegion* r) {
1134 HeapRegionRemSet* hrrs = r->rem_set();
1135
1136 _g1h->reset_gc_time_stamps(r);
1137
1138 if (r->is_continues_humongous()) {
1139 // We'll assert that the strong code root list and RSet is empty
1140 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1141 assert(hrrs->occupied() == 0, "RSet should be empty");
1142 } else {
1143 hrrs->clear();
1144 }
1145 // You might think here that we could clear just the cards
1146 // corresponding to the used region. But no: if we leave a dirty card
1147 // in a region we might allocate into, then it would prevent that card
1148 // from being enqueued, and cause it to be missed.
1149 // Re: the performance cost: we shouldn't be doing full GC anyway!
1150 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1151
1152 return false;
1153 }
1154 };
1155
1156 void G1CollectedHeap::clear_rsets_post_compaction() {
1157 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1158 heap_region_iterate(&rs_clear);
1159 }
1160
1161 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1162 G1CollectedHeap* _g1h;
1163 UpdateRSOopClosure _cl;
1164 public:
1165 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1166 _cl(g1->g1_rem_set(), worker_i),
1167 _g1h(g1)
1168 { }
1169
1170 bool doHeapRegion(HeapRegion* r) {
1171 if (!r->is_continues_humongous()) {
1172 _cl.set_from(r);
1173 r->oop_iterate(&_cl);
1174 }
1175 return false;
1176 }
1177 };
1178
1179 class ParRebuildRSTask: public AbstractGangTask {
1180 G1CollectedHeap* _g1;
1181 HeapRegionClaimer _hrclaimer;
1182
1183 public:
1184 ParRebuildRSTask(G1CollectedHeap* g1) :
1185 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1186
1187 void work(uint worker_id) {
1188 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1189 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1190 }
1191 };
1192
1193 class PostCompactionPrinterClosure: public HeapRegionClosure {
1194 private:
1195 G1HRPrinter* _hr_printer;
1196 public:
1197 bool doHeapRegion(HeapRegion* hr) {
1198 assert(!hr->is_young(), "not expecting to find young regions");
1199 _hr_printer->post_compaction(hr);
1200 return false;
1201 }
1202
1203 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1204 : _hr_printer(hr_printer) { }
1205 };
1206
1207 void G1CollectedHeap::print_hrm_post_compaction() {
1208 if (_hr_printer.is_active()) {
1209 PostCompactionPrinterClosure cl(hr_printer());
1210 heap_region_iterate(&cl);
1211 }
1212
1213 }
1214
1215 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1216 bool clear_all_soft_refs) {
1217 assert_at_safepoint(true /* should_be_vm_thread */);
1218
1219 if (GCLocker::check_active_before_gc()) {
1220 return false;
1221 }
1222
1223 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1224 gc_timer->register_gc_start();
1225
1226 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1227 GCIdMark gc_id_mark;
1228 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1229
1230 SvcGCMarker sgcm(SvcGCMarker::FULL);
1231 ResourceMark rm;
1232
1233 print_heap_before_gc();
1234 print_heap_regions();
1235 trace_heap_before_gc(gc_tracer);
1236
1237 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1238
1239 _verifier->verify_region_sets_optional();
1240
1241 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1242 collector_policy()->should_clear_all_soft_refs();
1243
1244 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1245
1246 {
1247 IsGCActiveMark x;
1248
1249 // Timing
1250 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1251 GCTraceCPUTime tcpu;
1252
1253 {
1254 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1255 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1256 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1257
1258 G1HeapTransition heap_transition(this);
1259 g1_policy()->record_full_collection_start();
1260
1261 // Note: When we have a more flexible GC logging framework that
1262 // allows us to add optional attributes to a GC log record we
1263 // could consider timing and reporting how long we wait in the
1264 // following two methods.
1265 wait_while_free_regions_coming();
1266 // If we start the compaction before the CM threads finish
1267 // scanning the root regions we might trip them over as we'll
1268 // be moving objects / updating references. So let's wait until
1269 // they are done. By telling them to abort, they should complete
1270 // early.
1271 _cm->root_regions()->abort();
1272 _cm->root_regions()->wait_until_scan_finished();
1273 append_secondary_free_list_if_not_empty_with_lock();
1274
1275 gc_prologue(true);
1276 increment_total_collections(true /* full gc */);
1277 increment_old_marking_cycles_started();
1278
1279 assert(used() == recalculate_used(), "Should be equal");
1280
1281 _verifier->verify_before_gc();
1282
1283 _verifier->check_bitmaps("Full GC Start");
1284 pre_full_gc_dump(gc_timer);
1285
1286 #if defined(COMPILER2) || INCLUDE_JVMCI
1287 DerivedPointerTable::clear();
1288 #endif
1289
1290 // Disable discovery and empty the discovered lists
1291 // for the CM ref processor.
1292 ref_processor_cm()->disable_discovery();
1293 ref_processor_cm()->abandon_partial_discovery();
1294 ref_processor_cm()->verify_no_references_recorded();
1295
1296 // Abandon current iterations of concurrent marking and concurrent
1297 // refinement, if any are in progress.
1298 concurrent_mark()->abort();
1299
1300 // Make sure we'll choose a new allocation region afterwards.
1301 _allocator->release_mutator_alloc_region();
1302 _allocator->abandon_gc_alloc_regions();
1303 g1_rem_set()->cleanupHRRS();
1304
1305 // We may have added regions to the current incremental collection
1306 // set between the last GC or pause and now. We need to clear the
1307 // incremental collection set and then start rebuilding it afresh
1308 // after this full GC.
1309 abandon_collection_set(collection_set()->inc_head());
1310 collection_set()->clear_incremental();
1311 collection_set()->stop_incremental_building();
1312
1313 tear_down_region_sets(false /* free_list_only */);
1314 collector_state()->set_gcs_are_young(true);
1315
1316 // See the comments in g1CollectedHeap.hpp and
1317 // G1CollectedHeap::ref_processing_init() about
1318 // how reference processing currently works in G1.
1319
1320 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1321 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1322
1323 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1324 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1325
1326 ref_processor_stw()->enable_discovery();
1327 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1328
1329 // Do collection work
1330 {
1331 HandleMark hm; // Discard invalid handles created during gc
1332 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1333 }
1334
1335 assert(num_free_regions() == 0, "we should not have added any free regions");
1336 rebuild_region_sets(false /* free_list_only */);
1337
1338 // Enqueue any discovered reference objects that have
1339 // not been removed from the discovered lists.
1340 ref_processor_stw()->enqueue_discovered_references();
1341
1342 #if defined(COMPILER2) || INCLUDE_JVMCI
1343 DerivedPointerTable::update_pointers();
1344 #endif
1345
1346 MemoryService::track_memory_usage();
1347
1348 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1349 ref_processor_stw()->verify_no_references_recorded();
1350
1351 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1352 ClassLoaderDataGraph::purge();
1353 MetaspaceAux::verify_metrics();
1354
1355 // Note: since we've just done a full GC, concurrent
1356 // marking is no longer active. Therefore we need not
1357 // re-enable reference discovery for the CM ref processor.
1358 // That will be done at the start of the next marking cycle.
1359 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1360 ref_processor_cm()->verify_no_references_recorded();
1361
1362 reset_gc_time_stamp();
1363 // Since everything potentially moved, we will clear all remembered
1364 // sets, and clear all cards. Later we will rebuild remembered
1365 // sets. We will also reset the GC time stamps of the regions.
1366 clear_rsets_post_compaction();
1367 check_gc_time_stamps();
1368
1369 resize_if_necessary_after_full_collection();
1370
1371 // We should do this after we potentially resize the heap so
1372 // that all the COMMIT / UNCOMMIT events are generated before
1373 // the compaction events.
1374 print_hrm_post_compaction();
1375
1376 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1377 if (hot_card_cache->use_cache()) {
1378 hot_card_cache->reset_card_counts();
1379 hot_card_cache->reset_hot_cache();
1380 }
1381
1382 // Rebuild remembered sets of all regions.
1383 uint n_workers =
1384 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1385 workers()->active_workers(),
1386 Threads::number_of_non_daemon_threads());
1387 workers()->set_active_workers(n_workers);
1388
1389 ParRebuildRSTask rebuild_rs_task(this);
1390 workers()->run_task(&rebuild_rs_task);
1391
1392 // Rebuild the strong code root lists for each region
1393 rebuild_strong_code_roots();
1394
1395 if (true) { // FIXME
1396 MetaspaceGC::compute_new_size();
1397 }
1398
1399 #ifdef TRACESPINNING
1400 ParallelTaskTerminator::print_termination_counts();
1401 #endif
1402
1403 // Discard all rset updates
1404 JavaThread::dirty_card_queue_set().abandon_logs();
1405 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1406
1407 // At this point there should be no regions in the
1408 // entire heap tagged as young.
1409 assert(check_young_list_empty(true /* check_heap */),
1410 "young list should be empty at this point");
1411
1412 // Update the number of full collections that have been completed.
1413 increment_old_marking_cycles_completed(false /* concurrent */);
1414
1415 _hrm.verify_optional();
1416 _verifier->verify_region_sets_optional();
1417
1418 _verifier->verify_after_gc();
1419
1420 // Clear the previous marking bitmap, if needed for bitmap verification.
1421 // Note we cannot do this when we clear the next marking bitmap in
1422 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423 // objects marked during a full GC against the previous bitmap.
1424 // But we need to clear it before calling check_bitmaps below since
1425 // the full GC has compacted objects and updated TAMS but not updated
1426 // the prev bitmap.
1427 if (G1VerifyBitmaps) {
1428 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1429 _cm->clear_prev_bitmap(workers());
1430 }
1431 _verifier->check_bitmaps("Full GC End");
1432
1433 // Start a new incremental collection set for the next pause
1434 assert(collection_set()->head() == NULL, "must be");
1435 collection_set()->start_incremental_building();
1436
1437 clear_cset_fast_test();
1438
1439 _allocator->init_mutator_alloc_region();
1440
1441 g1_policy()->record_full_collection_end();
1442
1443 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1444 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1445 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1446 // before any GC notifications are raised.
1447 g1mm()->update_sizes();
1448
1449 gc_epilogue(true);
1450
1451 heap_transition.print();
1452
1453 print_heap_after_gc();
1454 print_heap_regions();
1455 trace_heap_after_gc(gc_tracer);
1456
1457 post_full_gc_dump(gc_timer);
1458 }
1459
1460 gc_timer->register_gc_end();
1461 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1462 }
1463
1464 return true;
1465 }
1466
1467 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1468 // Currently, there is no facility in the do_full_collection(bool) API to notify
1469 // the caller that the collection did not succeed (e.g., because it was locked
1470 // out by the GC locker). So, right now, we'll ignore the return value.
1471 bool dummy = do_full_collection(true, /* explicit_gc */
1472 clear_all_soft_refs);
1473 }
1474
1475 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1476 // Include bytes that will be pre-allocated to support collections, as "used".
1477 const size_t used_after_gc = used();
1478 const size_t capacity_after_gc = capacity();
1479 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1480
1481 // This is enforced in arguments.cpp.
1482 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1483 "otherwise the code below doesn't make sense");
1484
1485 // We don't have floating point command-line arguments
1486 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1487 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1488 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1489 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1490
1491 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1492 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1493
1494 // We have to be careful here as these two calculations can overflow
1495 // 32-bit size_t's.
1496 double used_after_gc_d = (double) used_after_gc;
1497 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1498 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1499
1500 // Let's make sure that they are both under the max heap size, which
1501 // by default will make them fit into a size_t.
1502 double desired_capacity_upper_bound = (double) max_heap_size;
1503 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1504 desired_capacity_upper_bound);
1505 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1506 desired_capacity_upper_bound);
1507
1508 // We can now safely turn them into size_t's.
1509 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1510 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1511
1512 // This assert only makes sense here, before we adjust them
1513 // with respect to the min and max heap size.
1514 assert(minimum_desired_capacity <= maximum_desired_capacity,
1515 "minimum_desired_capacity = " SIZE_FORMAT ", "
1516 "maximum_desired_capacity = " SIZE_FORMAT,
1517 minimum_desired_capacity, maximum_desired_capacity);
1518
1519 // Should not be greater than the heap max size. No need to adjust
1520 // it with respect to the heap min size as it's a lower bound (i.e.,
1521 // we'll try to make the capacity larger than it, not smaller).
1522 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1523 // Should not be less than the heap min size. No need to adjust it
1524 // with respect to the heap max size as it's an upper bound (i.e.,
1525 // we'll try to make the capacity smaller than it, not greater).
1526 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1527
1528 if (capacity_after_gc < minimum_desired_capacity) {
1529 // Don't expand unless it's significant
1530 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1531
1532 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1533 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1534 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1535
1536 expand(expand_bytes);
1537
1538 // No expansion, now see if we want to shrink
1539 } else if (capacity_after_gc > maximum_desired_capacity) {
1540 // Capacity too large, compute shrinking size
1541 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1542
1543 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1544 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1545 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1546
1547 shrink(shrink_bytes);
1548 }
1549 }
1550
1551 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1552 AllocationContext_t context,
1553 bool do_gc,
1554 bool clear_all_soft_refs,
1555 bool expect_null_mutator_alloc_region,
1556 bool* gc_succeeded) {
1557 *gc_succeeded = true;
1558 // Let's attempt the allocation first.
1559 HeapWord* result =
1560 attempt_allocation_at_safepoint(word_size,
1561 context,
1562 expect_null_mutator_alloc_region);
1563 if (result != NULL) {
1564 assert(*gc_succeeded, "sanity");
1565 return result;
1566 }
1567
1568 // In a G1 heap, we're supposed to keep allocation from failing by
1569 // incremental pauses. Therefore, at least for now, we'll favor
1570 // expansion over collection. (This might change in the future if we can
1571 // do something smarter than full collection to satisfy a failed alloc.)
1572 result = expand_and_allocate(word_size, context);
1573 if (result != NULL) {
1574 assert(*gc_succeeded, "sanity");
1575 return result;
1576 }
1577
1578 if (do_gc) {
1579 // Expansion didn't work, we'll try to do a Full GC.
1580 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1581 clear_all_soft_refs);
1582 }
1583
1584 return NULL;
1585 }
1586
1587 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1588 AllocationContext_t context,
1589 bool* succeeded) {
1590 assert_at_safepoint(true /* should_be_vm_thread */);
1591
1592 // Attempts to allocate followed by Full GC.
1593 HeapWord* result =
1594 satisfy_failed_allocation_helper(word_size,
1595 context,
1596 true, /* do_gc */
1597 false, /* clear_all_soft_refs */
1598 false, /* expect_null_mutator_alloc_region */
1599 succeeded);
1600
1601 if (result != NULL || !*succeeded) {
1602 return result;
1603 }
1604
1605 // Attempts to allocate followed by Full GC that will collect all soft references.
1606 result = satisfy_failed_allocation_helper(word_size,
1607 context,
1608 true, /* do_gc */
1609 true, /* clear_all_soft_refs */
1610 true, /* expect_null_mutator_alloc_region */
1611 succeeded);
1612
1613 if (result != NULL || !*succeeded) {
1614 return result;
1615 }
1616
1617 // Attempts to allocate, no GC
1618 result = satisfy_failed_allocation_helper(word_size,
1619 context,
1620 false, /* do_gc */
1621 false, /* clear_all_soft_refs */
1622 true, /* expect_null_mutator_alloc_region */
1623 succeeded);
1624
1625 if (result != NULL) {
1626 assert(*succeeded, "sanity");
1627 return result;
1628 }
1629
1630 assert(!collector_policy()->should_clear_all_soft_refs(),
1631 "Flag should have been handled and cleared prior to this point");
1632
1633 // What else? We might try synchronous finalization later. If the total
1634 // space available is large enough for the allocation, then a more
1635 // complete compaction phase than we've tried so far might be
1636 // appropriate.
1637 assert(*succeeded, "sanity");
1638 return NULL;
1639 }
1640
1641 // Attempting to expand the heap sufficiently
1642 // to support an allocation of the given "word_size". If
1643 // successful, perform the allocation and return the address of the
1644 // allocated block, or else "NULL".
1645
1646 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1647 assert_at_safepoint(true /* should_be_vm_thread */);
1648
1649 _verifier->verify_region_sets_optional();
1650
1651 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1652 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1653 word_size * HeapWordSize);
1654
1655
1656 if (expand(expand_bytes)) {
1657 _hrm.verify_optional();
1658 _verifier->verify_region_sets_optional();
1659 return attempt_allocation_at_safepoint(word_size,
1660 context,
1661 false /* expect_null_mutator_alloc_region */);
1662 }
1663 return NULL;
1664 }
1665
1666 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1667 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1668 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1669 HeapRegion::GrainBytes);
1670
1671 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1672 expand_bytes, aligned_expand_bytes);
1673
1674 if (is_maximal_no_gc()) {
1675 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1676 return false;
1677 }
1678
1679 double expand_heap_start_time_sec = os::elapsedTime();
1680 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1681 assert(regions_to_expand > 0, "Must expand by at least one region");
1682
1683 uint expanded_by = _hrm.expand_by(regions_to_expand);
1684 if (expand_time_ms != NULL) {
1685 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1686 }
1687
1688 if (expanded_by > 0) {
1689 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1690 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1691 g1_policy()->record_new_heap_size(num_regions());
1692 } else {
1693 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1694
1695 // The expansion of the virtual storage space was unsuccessful.
1696 // Let's see if it was because we ran out of swap.
1697 if (G1ExitOnExpansionFailure &&
1698 _hrm.available() >= regions_to_expand) {
1699 // We had head room...
1700 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1701 }
1702 }
1703 return regions_to_expand > 0;
1704 }
1705
1706 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1707 size_t aligned_shrink_bytes =
1708 ReservedSpace::page_align_size_down(shrink_bytes);
1709 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1710 HeapRegion::GrainBytes);
1711 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1712
1713 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1714 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1715
1716
1717 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1718 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1719 if (num_regions_removed > 0) {
1720 g1_policy()->record_new_heap_size(num_regions());
1721 } else {
1722 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1723 }
1724 }
1725
1726 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1727 _verifier->verify_region_sets_optional();
1728
1729 // We should only reach here at the end of a Full GC which means we
1730 // should not not be holding to any GC alloc regions. The method
1731 // below will make sure of that and do any remaining clean up.
1732 _allocator->abandon_gc_alloc_regions();
1733
1734 // Instead of tearing down / rebuilding the free lists here, we
1735 // could instead use the remove_all_pending() method on free_list to
1736 // remove only the ones that we need to remove.
1737 tear_down_region_sets(true /* free_list_only */);
1738 shrink_helper(shrink_bytes);
1739 rebuild_region_sets(true /* free_list_only */);
1740
1741 _hrm.verify_optional();
1742 _verifier->verify_region_sets_optional();
1743 }
1744
1745 // Public methods.
1746
1747 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1748 CollectedHeap(),
1749 _g1_policy(policy_),
1750 _collection_set(this),
1751 _dirty_card_queue_set(false),
1752 _is_alive_closure_cm(this),
1753 _is_alive_closure_stw(this),
1754 _ref_processor_cm(NULL),
1755 _ref_processor_stw(NULL),
1756 _bot(NULL),
1757 _cg1r(NULL),
1758 _g1mm(NULL),
1759 _refine_cte_cl(NULL),
1760 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1761 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1762 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1763 _humongous_reclaim_candidates(),
1764 _has_humongous_reclaim_candidates(false),
1765 _archive_allocator(NULL),
1766 _free_regions_coming(false),
1767 _young_list(new YoungList(this)),
1768 _gc_time_stamp(0),
1769 _summary_bytes_used(0),
1770 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1771 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1772 _expand_heap_after_alloc_failure(true),
1773 _old_marking_cycles_started(0),
1774 _old_marking_cycles_completed(0),
1775 _in_cset_fast_test(),
1776 _dirty_cards_region_list(NULL),
1777 _worker_cset_start_region(NULL),
1778 _worker_cset_start_region_time_stamp(NULL),
1779 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1780 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1781
1782 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1783 /* are_GC_task_threads */true,
1784 /* are_ConcurrentGC_threads */false);
1785 _workers->initialize_workers();
1786 _verifier = new G1HeapVerifier(this);
1787
1788 _allocator = G1Allocator::create_allocator(this);
1789
1790 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1791
1792 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1793
1794 // Override the default _filler_array_max_size so that no humongous filler
1795 // objects are created.
1796 _filler_array_max_size = _humongous_object_threshold_in_words;
1797
1798 uint n_queues = ParallelGCThreads;
1799 _task_queues = new RefToScanQueueSet(n_queues);
1800
1801 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1802 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1803 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1804
1805 for (uint i = 0; i < n_queues; i++) {
1806 RefToScanQueue* q = new RefToScanQueue();
1807 q->initialize();
1808 _task_queues->register_queue(i, q);
1809 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1810 }
1811 clear_cset_start_regions();
1812
1813 // Initialize the G1EvacuationFailureALot counters and flags.
1814 NOT_PRODUCT(reset_evacuation_should_fail();)
1815
1816 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1817 }
1818
1819 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1820 size_t size,
1821 size_t translation_factor) {
1822 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1823 // Allocate a new reserved space, preferring to use large pages.
1824 ReservedSpace rs(size, preferred_page_size);
1825 G1RegionToSpaceMapper* result =
1826 G1RegionToSpaceMapper::create_mapper(rs,
1827 size,
1828 rs.alignment(),
1829 HeapRegion::GrainBytes,
1830 translation_factor,
1831 mtGC);
1832
1833 os::trace_page_sizes_for_requested_size(description,
1834 size,
1835 preferred_page_size,
1836 rs.alignment(),
1837 rs.base(),
1838 rs.size());
1839
1840 return result;
1841 }
1842
1843 jint G1CollectedHeap::initialize() {
1844 CollectedHeap::pre_initialize();
1845 os::enable_vtime();
1846
1847 // Necessary to satisfy locking discipline assertions.
1848
1849 MutexLocker x(Heap_lock);
1850
1851 // While there are no constraints in the GC code that HeapWordSize
1852 // be any particular value, there are multiple other areas in the
1853 // system which believe this to be true (e.g. oop->object_size in some
1854 // cases incorrectly returns the size in wordSize units rather than
1855 // HeapWordSize).
1856 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1857
1858 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1859 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1860 size_t heap_alignment = collector_policy()->heap_alignment();
1861
1862 // Ensure that the sizes are properly aligned.
1863 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1864 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1866
1867 _refine_cte_cl = new RefineCardTableEntryClosure();
1868
1869 jint ecode = JNI_OK;
1870 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1871 if (_cg1r == NULL) {
1872 return ecode;
1873 }
1874
1875 // Reserve the maximum.
1876
1877 // When compressed oops are enabled, the preferred heap base
1878 // is calculated by subtracting the requested size from the
1879 // 32Gb boundary and using the result as the base address for
1880 // heap reservation. If the requested size is not aligned to
1881 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1882 // into the ReservedHeapSpace constructor) then the actual
1883 // base of the reserved heap may end up differing from the
1884 // address that was requested (i.e. the preferred heap base).
1885 // If this happens then we could end up using a non-optimal
1886 // compressed oops mode.
1887
1888 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1889 heap_alignment);
1890
1891 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1892
1893 // Create the barrier set for the entire reserved region.
1894 G1SATBCardTableLoggingModRefBS* bs
1895 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1896 bs->initialize();
1897 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1898 set_barrier_set(bs);
1899
1900 // Also create a G1 rem set.
1901 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1902
1903 // Carve out the G1 part of the heap.
1904 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1905 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1906 G1RegionToSpaceMapper* heap_storage =
1907 G1RegionToSpaceMapper::create_mapper(g1_rs,
1908 g1_rs.size(),
1909 page_size,
1910 HeapRegion::GrainBytes,
1911 1,
1912 mtJavaHeap);
1913 os::trace_page_sizes("Heap", collector_policy()->min_heap_byte_size(),
1914 max_byte_size, page_size,
1915 heap_rs.base(),
1916 heap_rs.size());
1917 heap_storage->set_mapping_changed_listener(&_listener);
1918
1919 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1920 G1RegionToSpaceMapper* bot_storage =
1921 create_aux_memory_mapper("Block Offset Table",
1922 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1923 G1BlockOffsetTable::heap_map_factor());
1924
1925 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1926 G1RegionToSpaceMapper* cardtable_storage =
1927 create_aux_memory_mapper("Card Table",
1928 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1929 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1930
1931 G1RegionToSpaceMapper* card_counts_storage =
1932 create_aux_memory_mapper("Card Counts Table",
1933 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1934 G1CardCounts::heap_map_factor());
1935
1936 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1937 G1RegionToSpaceMapper* prev_bitmap_storage =
1938 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1939 G1RegionToSpaceMapper* next_bitmap_storage =
1940 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1941
1942 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1943 g1_barrier_set()->initialize(cardtable_storage);
1944 // Do later initialization work for concurrent refinement.
1945 _cg1r->init(card_counts_storage);
1946
1947 // 6843694 - ensure that the maximum region index can fit
1948 // in the remembered set structures.
1949 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1950 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1951
1952 g1_rem_set()->initialize(max_capacity(), max_regions());
1953
1954 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1955 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1956 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1957 "too many cards per region");
1958
1959 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1960
1961 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1962
1963 {
1964 HeapWord* start = _hrm.reserved().start();
1965 HeapWord* end = _hrm.reserved().end();
1966 size_t granularity = HeapRegion::GrainBytes;
1967
1968 _in_cset_fast_test.initialize(start, end, granularity);
1969 _humongous_reclaim_candidates.initialize(start, end, granularity);
1970 }
1971
1972 // Create the G1ConcurrentMark data structure and thread.
1973 // (Must do this late, so that "max_regions" is defined.)
1974 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1975 if (_cm == NULL || !_cm->completed_initialization()) {
1976 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1977 return JNI_ENOMEM;
1978 }
1979 _cmThread = _cm->cmThread();
1980
1981 // Now expand into the initial heap size.
1982 if (!expand(init_byte_size)) {
1983 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1984 return JNI_ENOMEM;
1985 }
1986
1987 // Perform any initialization actions delegated to the policy.
1988 g1_policy()->init();
1989
1990 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1991 SATB_Q_FL_lock,
1992 G1SATBProcessCompletedThreshold,
1993 Shared_SATB_Q_lock);
1994
1995 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1996 DirtyCardQ_CBL_mon,
1997 DirtyCardQ_FL_lock,
1998 (int)concurrent_g1_refine()->yellow_zone(),
1999 (int)concurrent_g1_refine()->red_zone(),
2000 Shared_DirtyCardQ_lock,
2001 NULL, // fl_owner
2002 true); // init_free_ids
2003
2004 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2005 DirtyCardQ_CBL_mon,
2006 DirtyCardQ_FL_lock,
2007 -1, // never trigger processing
2008 -1, // no limit on length
2009 Shared_DirtyCardQ_lock,
2010 &JavaThread::dirty_card_queue_set());
2011
2012 // Here we allocate the dummy HeapRegion that is required by the
2013 // G1AllocRegion class.
2014 HeapRegion* dummy_region = _hrm.get_dummy_region();
2015
2016 // We'll re-use the same region whether the alloc region will
2017 // require BOT updates or not and, if it doesn't, then a non-young
2018 // region will complain that it cannot support allocations without
2019 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2020 dummy_region->set_eden();
2021 // Make sure it's full.
2022 dummy_region->set_top(dummy_region->end());
2023 G1AllocRegion::setup(this, dummy_region);
2024
2025 _allocator->init_mutator_alloc_region();
2026
2027 // Do create of the monitoring and management support so that
2028 // values in the heap have been properly initialized.
2029 _g1mm = new G1MonitoringSupport(this);
2030
2031 G1StringDedup::initialize();
2032
2033 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2034 for (uint i = 0; i < ParallelGCThreads; i++) {
2035 new (&_preserved_objs[i]) OopAndMarkOopStack();
2036 }
2037
2038 return JNI_OK;
2039 }
2040
2041 void G1CollectedHeap::stop() {
2042 // Stop all concurrent threads. We do this to make sure these threads
2043 // do not continue to execute and access resources (e.g. logging)
2044 // that are destroyed during shutdown.
2045 _cg1r->stop();
2046 _cmThread->stop();
2047 if (G1StringDedup::is_enabled()) {
2048 G1StringDedup::stop();
2049 }
2050 }
2051
2052 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2053 return HeapRegion::max_region_size();
2054 }
2055
2056 void G1CollectedHeap::post_initialize() {
2057 CollectedHeap::post_initialize();
2058 ref_processing_init();
2059 }
2060
2061 void G1CollectedHeap::ref_processing_init() {
2062 // Reference processing in G1 currently works as follows:
2063 //
2064 // * There are two reference processor instances. One is
2065 // used to record and process discovered references
2066 // during concurrent marking; the other is used to
2067 // record and process references during STW pauses
2068 // (both full and incremental).
2069 // * Both ref processors need to 'span' the entire heap as
2070 // the regions in the collection set may be dotted around.
2071 //
2072 // * For the concurrent marking ref processor:
2073 // * Reference discovery is enabled at initial marking.
2074 // * Reference discovery is disabled and the discovered
2075 // references processed etc during remarking.
2076 // * Reference discovery is MT (see below).
2077 // * Reference discovery requires a barrier (see below).
2078 // * Reference processing may or may not be MT
2079 // (depending on the value of ParallelRefProcEnabled
2080 // and ParallelGCThreads).
2081 // * A full GC disables reference discovery by the CM
2082 // ref processor and abandons any entries on it's
2083 // discovered lists.
2084 //
2085 // * For the STW processor:
2086 // * Non MT discovery is enabled at the start of a full GC.
2087 // * Processing and enqueueing during a full GC is non-MT.
2088 // * During a full GC, references are processed after marking.
2089 //
2090 // * Discovery (may or may not be MT) is enabled at the start
2091 // of an incremental evacuation pause.
2092 // * References are processed near the end of a STW evacuation pause.
2093 // * For both types of GC:
2094 // * Discovery is atomic - i.e. not concurrent.
2095 // * Reference discovery will not need a barrier.
2096
2097 MemRegion mr = reserved_region();
2098
2099 // Concurrent Mark ref processor
2100 _ref_processor_cm =
2101 new ReferenceProcessor(mr, // span
2102 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2103 // mt processing
2104 ParallelGCThreads,
2105 // degree of mt processing
2106 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2107 // mt discovery
2108 MAX2(ParallelGCThreads, ConcGCThreads),
2109 // degree of mt discovery
2110 false,
2111 // Reference discovery is not atomic
2112 &_is_alive_closure_cm);
2113 // is alive closure
2114 // (for efficiency/performance)
2115
2116 // STW ref processor
2117 _ref_processor_stw =
2118 new ReferenceProcessor(mr, // span
2119 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2120 // mt processing
2121 ParallelGCThreads,
2122 // degree of mt processing
2123 (ParallelGCThreads > 1),
2124 // mt discovery
2125 ParallelGCThreads,
2126 // degree of mt discovery
2127 true,
2128 // Reference discovery is atomic
2129 &_is_alive_closure_stw);
2130 // is alive closure
2131 // (for efficiency/performance)
2132 }
2133
2134 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2135 return g1_policy();
2136 }
2137
2138 size_t G1CollectedHeap::capacity() const {
2139 return _hrm.length() * HeapRegion::GrainBytes;
2140 }
2141
2142 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2143 hr->reset_gc_time_stamp();
2144 }
2145
2146 #ifndef PRODUCT
2147
2148 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2149 private:
2150 unsigned _gc_time_stamp;
2151 bool _failures;
2152
2153 public:
2154 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2155 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2156
2157 virtual bool doHeapRegion(HeapRegion* hr) {
2158 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2159 if (_gc_time_stamp != region_gc_time_stamp) {
2160 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2161 region_gc_time_stamp, _gc_time_stamp);
2162 _failures = true;
2163 }
2164 return false;
2165 }
2166
2167 bool failures() { return _failures; }
2168 };
2169
2170 void G1CollectedHeap::check_gc_time_stamps() {
2171 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2172 heap_region_iterate(&cl);
2173 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2174 }
2175 #endif // PRODUCT
2176
2177 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2178 _cg1r->hot_card_cache()->drain(cl, worker_i);
2179 }
2180
2181 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2182 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2183 size_t n_completed_buffers = 0;
2184 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2185 n_completed_buffers++;
2186 }
2187 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2188 dcqs.clear_n_completed_buffers();
2189 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2190 }
2191
2192 // Computes the sum of the storage used by the various regions.
2193 size_t G1CollectedHeap::used() const {
2194 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2195 if (_archive_allocator != NULL) {
2196 result += _archive_allocator->used();
2197 }
2198 return result;
2199 }
2200
2201 size_t G1CollectedHeap::used_unlocked() const {
2202 return _summary_bytes_used;
2203 }
2204
2205 class SumUsedClosure: public HeapRegionClosure {
2206 size_t _used;
2207 public:
2208 SumUsedClosure() : _used(0) {}
2209 bool doHeapRegion(HeapRegion* r) {
2210 _used += r->used();
2211 return false;
2212 }
2213 size_t result() { return _used; }
2214 };
2215
2216 size_t G1CollectedHeap::recalculate_used() const {
2217 double recalculate_used_start = os::elapsedTime();
2218
2219 SumUsedClosure blk;
2220 heap_region_iterate(&blk);
2221
2222 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2223 return blk.result();
2224 }
2225
2226 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2227 switch (cause) {
2228 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2229 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2230 case GCCause::_update_allocation_context_stats_inc: return true;
2231 case GCCause::_wb_conc_mark: return true;
2232 default : return false;
2233 }
2234 }
2235
2236 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2237 switch (cause) {
2238 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2239 case GCCause::_g1_humongous_allocation: return true;
2240 default: return is_user_requested_concurrent_full_gc(cause);
2241 }
2242 }
2243
2244 #ifndef PRODUCT
2245 void G1CollectedHeap::allocate_dummy_regions() {
2246 // Let's fill up most of the region
2247 size_t word_size = HeapRegion::GrainWords - 1024;
2248 // And as a result the region we'll allocate will be humongous.
2249 guarantee(is_humongous(word_size), "sanity");
2250
2251 // _filler_array_max_size is set to humongous object threshold
2252 // but temporarily change it to use CollectedHeap::fill_with_object().
2253 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2254
2255 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2256 // Let's use the existing mechanism for the allocation
2257 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2258 AllocationContext::system());
2259 if (dummy_obj != NULL) {
2260 MemRegion mr(dummy_obj, word_size);
2261 CollectedHeap::fill_with_object(mr);
2262 } else {
2263 // If we can't allocate once, we probably cannot allocate
2264 // again. Let's get out of the loop.
2265 break;
2266 }
2267 }
2268 }
2269 #endif // !PRODUCT
2270
2271 void G1CollectedHeap::increment_old_marking_cycles_started() {
2272 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2273 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2274 "Wrong marking cycle count (started: %d, completed: %d)",
2275 _old_marking_cycles_started, _old_marking_cycles_completed);
2276
2277 _old_marking_cycles_started++;
2278 }
2279
2280 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2281 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2282
2283 // We assume that if concurrent == true, then the caller is a
2284 // concurrent thread that was joined the Suspendible Thread
2285 // Set. If there's ever a cheap way to check this, we should add an
2286 // assert here.
2287
2288 // Given that this method is called at the end of a Full GC or of a
2289 // concurrent cycle, and those can be nested (i.e., a Full GC can
2290 // interrupt a concurrent cycle), the number of full collections
2291 // completed should be either one (in the case where there was no
2292 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2293 // behind the number of full collections started.
2294
2295 // This is the case for the inner caller, i.e. a Full GC.
2296 assert(concurrent ||
2297 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2298 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2299 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2300 "is inconsistent with _old_marking_cycles_completed = %u",
2301 _old_marking_cycles_started, _old_marking_cycles_completed);
2302
2303 // This is the case for the outer caller, i.e. the concurrent cycle.
2304 assert(!concurrent ||
2305 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2306 "for outer caller (concurrent cycle): "
2307 "_old_marking_cycles_started = %u "
2308 "is inconsistent with _old_marking_cycles_completed = %u",
2309 _old_marking_cycles_started, _old_marking_cycles_completed);
2310
2311 _old_marking_cycles_completed += 1;
2312
2313 // We need to clear the "in_progress" flag in the CM thread before
2314 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2315 // is set) so that if a waiter requests another System.gc() it doesn't
2316 // incorrectly see that a marking cycle is still in progress.
2317 if (concurrent) {
2318 _cmThread->set_idle();
2319 }
2320
2321 // This notify_all() will ensure that a thread that called
2322 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2323 // and it's waiting for a full GC to finish will be woken up. It is
2324 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2325 FullGCCount_lock->notify_all();
2326 }
2327
2328 void G1CollectedHeap::collect(GCCause::Cause cause) {
2329 assert_heap_not_locked();
2330
2331 uint gc_count_before;
2332 uint old_marking_count_before;
2333 uint full_gc_count_before;
2334 bool retry_gc;
2335
2336 do {
2337 retry_gc = false;
2338
2339 {
2340 MutexLocker ml(Heap_lock);
2341
2342 // Read the GC count while holding the Heap_lock
2343 gc_count_before = total_collections();
2344 full_gc_count_before = total_full_collections();
2345 old_marking_count_before = _old_marking_cycles_started;
2346 }
2347
2348 if (should_do_concurrent_full_gc(cause)) {
2349 // Schedule an initial-mark evacuation pause that will start a
2350 // concurrent cycle. We're setting word_size to 0 which means that
2351 // we are not requesting a post-GC allocation.
2352 VM_G1IncCollectionPause op(gc_count_before,
2353 0, /* word_size */
2354 true, /* should_initiate_conc_mark */
2355 g1_policy()->max_pause_time_ms(),
2356 cause);
2357 op.set_allocation_context(AllocationContext::current());
2358
2359 VMThread::execute(&op);
2360 if (!op.pause_succeeded()) {
2361 if (old_marking_count_before == _old_marking_cycles_started) {
2362 retry_gc = op.should_retry_gc();
2363 } else {
2364 // A Full GC happened while we were trying to schedule the
2365 // initial-mark GC. No point in starting a new cycle given
2366 // that the whole heap was collected anyway.
2367 }
2368
2369 if (retry_gc) {
2370 if (GCLocker::is_active_and_needs_gc()) {
2371 GCLocker::stall_until_clear();
2372 }
2373 }
2374 }
2375 } else {
2376 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2377 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2378
2379 // Schedule a standard evacuation pause. We're setting word_size
2380 // to 0 which means that we are not requesting a post-GC allocation.
2381 VM_G1IncCollectionPause op(gc_count_before,
2382 0, /* word_size */
2383 false, /* should_initiate_conc_mark */
2384 g1_policy()->max_pause_time_ms(),
2385 cause);
2386 VMThread::execute(&op);
2387 } else {
2388 // Schedule a Full GC.
2389 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2390 VMThread::execute(&op);
2391 }
2392 }
2393 } while (retry_gc);
2394 }
2395
2396 bool G1CollectedHeap::is_in(const void* p) const {
2397 if (_hrm.reserved().contains(p)) {
2398 // Given that we know that p is in the reserved space,
2399 // heap_region_containing() should successfully
2400 // return the containing region.
2401 HeapRegion* hr = heap_region_containing(p);
2402 return hr->is_in(p);
2403 } else {
2404 return false;
2405 }
2406 }
2407
2408 #ifdef ASSERT
2409 bool G1CollectedHeap::is_in_exact(const void* p) const {
2410 bool contains = reserved_region().contains(p);
2411 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2412 if (contains && available) {
2413 return true;
2414 } else {
2415 return false;
2416 }
2417 }
2418 #endif
2419
2420 bool G1CollectedHeap::obj_in_cs(oop obj) {
2421 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2422 return r != NULL && r->in_collection_set();
2423 }
2424
2425 // Iteration functions.
2426
2427 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2428
2429 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2430 ExtendedOopClosure* _cl;
2431 public:
2432 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2433 bool doHeapRegion(HeapRegion* r) {
2434 if (!r->is_continues_humongous()) {
2435 r->oop_iterate(_cl);
2436 }
2437 return false;
2438 }
2439 };
2440
2441 // Iterates an ObjectClosure over all objects within a HeapRegion.
2442
2443 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2444 ObjectClosure* _cl;
2445 public:
2446 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2447 bool doHeapRegion(HeapRegion* r) {
2448 if (!r->is_continues_humongous()) {
2449 r->object_iterate(_cl);
2450 }
2451 return false;
2452 }
2453 };
2454
2455 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2456 IterateObjectClosureRegionClosure blk(cl);
2457 heap_region_iterate(&blk);
2458 }
2459
2460 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2461 _hrm.iterate(cl);
2462 }
2463
2464 void
2465 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2466 uint worker_id,
2467 HeapRegionClaimer *hrclaimer,
2468 bool concurrent) const {
2469 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2470 }
2471
2472 // Clear the cached CSet starting regions and (more importantly)
2473 // the time stamps. Called when we reset the GC time stamp.
2474 void G1CollectedHeap::clear_cset_start_regions() {
2475 assert(_worker_cset_start_region != NULL, "sanity");
2476 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2477
2478 for (uint i = 0; i < ParallelGCThreads; i++) {
2479 _worker_cset_start_region[i] = NULL;
2480 _worker_cset_start_region_time_stamp[i] = 0;
2481 }
2482 }
2483
2484 // Given the id of a worker, obtain or calculate a suitable
2485 // starting region for iterating over the current collection set.
2486 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2487 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2488
2489 HeapRegion* result = NULL;
2490 unsigned gc_time_stamp = get_gc_time_stamp();
2491
2492 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2493 // Cached starting region for current worker was set
2494 // during the current pause - so it's valid.
2495 // Note: the cached starting heap region may be NULL
2496 // (when the collection set is empty).
2497 result = _worker_cset_start_region[worker_i];
2498 assert(result == NULL || result->in_collection_set(), "sanity");
2499 return result;
2500 }
2501
2502 // The cached entry was not valid so let's calculate
2503 // a suitable starting heap region for this worker.
2504
2505 // We want the parallel threads to start their collection
2506 // set iteration at different collection set regions to
2507 // avoid contention.
2508 // If we have:
2509 // n collection set regions
2510 // p threads
2511 // Then thread t will start at region floor ((t * n) / p)
2512
2513 result = collection_set()->head();
2514 uint cs_size = collection_set()->region_length();
2515 uint active_workers = workers()->active_workers();
2516
2517 uint end_ind = (cs_size * worker_i) / active_workers;
2518 uint start_ind = 0;
2519
2520 if (worker_i > 0 &&
2521 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2522 // Previous workers starting region is valid
2523 // so let's iterate from there
2524 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2525 OrderAccess::loadload();
2526 result = _worker_cset_start_region[worker_i - 1];
2527 }
2528
2529 for (uint i = start_ind; i < end_ind; i++) {
2530 result = result->next_in_collection_set();
2531 }
2532
2533 // Note: the calculated starting heap region may be NULL
2534 // (when the collection set is empty).
2535 assert(result == NULL || result->in_collection_set(), "sanity");
2536 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2537 "should be updated only once per pause");
2538 _worker_cset_start_region[worker_i] = result;
2539 OrderAccess::storestore();
2540 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2541 return result;
2542 }
2543
2544 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2545 HeapRegion* r = collection_set()->head();
2546 while (r != NULL) {
2547 HeapRegion* next = r->next_in_collection_set();
2548 if (cl->doHeapRegion(r)) {
2549 cl->incomplete();
2550 return;
2551 }
2552 r = next;
2553 }
2554 }
2555
2556 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2557 HeapRegionClosure *cl) {
2558 if (r == NULL) {
2559 // The CSet is empty so there's nothing to do.
2560 return;
2561 }
2562
2563 assert(r->in_collection_set(),
2564 "Start region must be a member of the collection set.");
2565 HeapRegion* cur = r;
2566 while (cur != NULL) {
2567 HeapRegion* next = cur->next_in_collection_set();
2568 if (cl->doHeapRegion(cur) && false) {
2569 cl->incomplete();
2570 return;
2571 }
2572 cur = next;
2573 }
2574 cur = collection_set()->head();
2575 while (cur != r) {
2576 HeapRegion* next = cur->next_in_collection_set();
2577 if (cl->doHeapRegion(cur) && false) {
2578 cl->incomplete();
2579 return;
2580 }
2581 cur = next;
2582 }
2583 }
2584
2585 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2586 HeapRegion* result = _hrm.next_region_in_heap(from);
2587 while (result != NULL && result->is_pinned()) {
2588 result = _hrm.next_region_in_heap(result);
2589 }
2590 return result;
2591 }
2592
2593 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2594 HeapRegion* hr = heap_region_containing(addr);
2595 return hr->block_start(addr);
2596 }
2597
2598 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2599 HeapRegion* hr = heap_region_containing(addr);
2600 return hr->block_size(addr);
2601 }
2602
2603 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2604 HeapRegion* hr = heap_region_containing(addr);
2605 return hr->block_is_obj(addr);
2606 }
2607
2608 bool G1CollectedHeap::supports_tlab_allocation() const {
2609 return true;
2610 }
2611
2612 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2613 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2614 }
2615
2616 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2617 return young_list()->eden_used_bytes();
2618 }
2619
2620 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2621 // must be equal to the humongous object limit.
2622 size_t G1CollectedHeap::max_tlab_size() const {
2623 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2624 }
2625
2626 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2627 AllocationContext_t context = AllocationContext::current();
2628 return _allocator->unsafe_max_tlab_alloc(context);
2629 }
2630
2631 size_t G1CollectedHeap::max_capacity() const {
2632 return _hrm.reserved().byte_size();
2633 }
2634
2635 jlong G1CollectedHeap::millis_since_last_gc() {
2636 // assert(false, "NYI");
2637 return 0;
2638 }
2639
2640 void G1CollectedHeap::prepare_for_verify() {
2641 _verifier->prepare_for_verify();
2642 }
2643
2644 void G1CollectedHeap::verify(VerifyOption vo) {
2645 _verifier->verify(vo);
2646 }
2647
2648 class PrintRegionClosure: public HeapRegionClosure {
2649 outputStream* _st;
2650 public:
2651 PrintRegionClosure(outputStream* st) : _st(st) {}
2652 bool doHeapRegion(HeapRegion* r) {
2653 r->print_on(_st);
2654 return false;
2655 }
2656 };
2657
2658 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2659 const HeapRegion* hr,
2660 const VerifyOption vo) const {
2661 switch (vo) {
2662 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2663 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2664 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2665 default: ShouldNotReachHere();
2666 }
2667 return false; // keep some compilers happy
2668 }
2669
2670 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2671 const VerifyOption vo) const {
2672 switch (vo) {
2673 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2674 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2675 case VerifyOption_G1UseMarkWord: {
2676 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2677 return !obj->is_gc_marked() && !hr->is_archive();
2678 }
2679 default: ShouldNotReachHere();
2680 }
2681 return false; // keep some compilers happy
2682 }
2683
2684 void G1CollectedHeap::print_heap_regions() const {
2685 Log(gc, heap, region) log;
2686 if (log.is_trace()) {
2687 ResourceMark rm;
2688 print_regions_on(log.trace_stream());
2689 }
2690 }
2691
2692 void G1CollectedHeap::print_on(outputStream* st) const {
2693 st->print(" %-20s", "garbage-first heap");
2694 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2695 capacity()/K, used_unlocked()/K);
2696 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2697 p2i(_hrm.reserved().start()),
2698 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2699 p2i(_hrm.reserved().end()));
2700 st->cr();
2701 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2702 uint young_regions = _young_list->length();
2703 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2704 (size_t) young_regions * HeapRegion::GrainBytes / K);
2705 uint survivor_regions = _young_list->survivor_length();
2706 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2707 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2708 st->cr();
2709 MetaspaceAux::print_on(st);
2710 }
2711
2712 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2713 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2714 "HS=humongous(starts), HC=humongous(continues), "
2715 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2716 "AC=allocation context, "
2717 "TAMS=top-at-mark-start (previous, next)");
2718 PrintRegionClosure blk(st);
2719 heap_region_iterate(&blk);
2720 }
2721
2722 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2723 print_on(st);
2724
2725 // Print the per-region information.
2726 print_regions_on(st);
2727 }
2728
2729 void G1CollectedHeap::print_on_error(outputStream* st) const {
2730 this->CollectedHeap::print_on_error(st);
2731
2732 if (_cm != NULL) {
2733 st->cr();
2734 _cm->print_on_error(st);
2735 }
2736 }
2737
2738 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2739 workers()->print_worker_threads_on(st);
2740 _cmThread->print_on(st);
2741 st->cr();
2742 _cm->print_worker_threads_on(st);
2743 _cg1r->print_worker_threads_on(st);
2744 if (G1StringDedup::is_enabled()) {
2745 G1StringDedup::print_worker_threads_on(st);
2746 }
2747 }
2748
2749 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2750 workers()->threads_do(tc);
2751 tc->do_thread(_cmThread);
2752 _cg1r->threads_do(tc);
2753 if (G1StringDedup::is_enabled()) {
2754 G1StringDedup::threads_do(tc);
2755 }
2756 }
2757
2758 void G1CollectedHeap::print_tracing_info() const {
2759 g1_rem_set()->print_summary_info();
2760 concurrent_mark()->print_summary_info();
2761 g1_policy()->print_yg_surv_rate_info();
2762 }
2763
2764 #ifndef PRODUCT
2765 // Helpful for debugging RSet issues.
2766
2767 class PrintRSetsClosure : public HeapRegionClosure {
2768 private:
2769 const char* _msg;
2770 size_t _occupied_sum;
2771
2772 public:
2773 bool doHeapRegion(HeapRegion* r) {
2774 HeapRegionRemSet* hrrs = r->rem_set();
2775 size_t occupied = hrrs->occupied();
2776 _occupied_sum += occupied;
2777
2778 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2779 if (occupied == 0) {
2780 tty->print_cr(" RSet is empty");
2781 } else {
2782 hrrs->print();
2783 }
2784 tty->print_cr("----------");
2785 return false;
2786 }
2787
2788 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2789 tty->cr();
2790 tty->print_cr("========================================");
2791 tty->print_cr("%s", msg);
2792 tty->cr();
2793 }
2794
2795 ~PrintRSetsClosure() {
2796 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2797 tty->print_cr("========================================");
2798 tty->cr();
2799 }
2800 };
2801
2802 void G1CollectedHeap::print_cset_rsets() {
2803 PrintRSetsClosure cl("Printing CSet RSets");
2804 collection_set_iterate(&cl);
2805 }
2806
2807 void G1CollectedHeap::print_all_rsets() {
2808 PrintRSetsClosure cl("Printing All RSets");;
2809 heap_region_iterate(&cl);
2810 }
2811 #endif // PRODUCT
2812
2813 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2814 YoungList* young_list = heap()->young_list();
2815
2816 size_t eden_used_bytes = young_list->eden_used_bytes();
2817 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2818 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2819
2820 size_t eden_capacity_bytes =
2821 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2822
2823 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2824 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2825 eden_capacity_bytes, survivor_used_bytes, num_regions());
2826 }
2827
2828 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2829 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2830 stats->unused(), stats->used(), stats->region_end_waste(),
2831 stats->regions_filled(), stats->direct_allocated(),
2832 stats->failure_used(), stats->failure_waste());
2833 }
2834
2835 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2836 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2837 gc_tracer->report_gc_heap_summary(when, heap_summary);
2838
2839 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2840 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2841 }
2842
2843 G1CollectedHeap* G1CollectedHeap::heap() {
2844 CollectedHeap* heap = Universe::heap();
2845 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2846 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2847 return (G1CollectedHeap*)heap;
2848 }
2849
2850 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2851 // always_do_update_barrier = false;
2852 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2853 // Fill TLAB's and such
2854 accumulate_statistics_all_tlabs();
2855 ensure_parsability(true);
2856
2857 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2858 }
2859
2860 void G1CollectedHeap::gc_epilogue(bool full) {
2861 // we are at the end of the GC. Total collections has already been increased.
2862 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2863
2864 // FIXME: what is this about?
2865 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2866 // is set.
2867 #if defined(COMPILER2) || INCLUDE_JVMCI
2868 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2869 #endif
2870 // always_do_update_barrier = true;
2871
2872 resize_all_tlabs();
2873 allocation_context_stats().update(full);
2874
2875 // We have just completed a GC. Update the soft reference
2876 // policy with the new heap occupancy
2877 Universe::update_heap_info_at_gc();
2878 }
2879
2880 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2881 uint gc_count_before,
2882 bool* succeeded,
2883 GCCause::Cause gc_cause) {
2884 assert_heap_not_locked_and_not_at_safepoint();
2885 VM_G1IncCollectionPause op(gc_count_before,
2886 word_size,
2887 false, /* should_initiate_conc_mark */
2888 g1_policy()->max_pause_time_ms(),
2889 gc_cause);
2890
2891 op.set_allocation_context(AllocationContext::current());
2892 VMThread::execute(&op);
2893
2894 HeapWord* result = op.result();
2895 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2896 assert(result == NULL || ret_succeeded,
2897 "the result should be NULL if the VM did not succeed");
2898 *succeeded = ret_succeeded;
2899
2900 assert_heap_not_locked();
2901 return result;
2902 }
2903
2904 void
2905 G1CollectedHeap::doConcurrentMark() {
2906 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2907 if (!_cmThread->in_progress()) {
2908 _cmThread->set_started();
2909 CGC_lock->notify();
2910 }
2911 }
2912
2913 size_t G1CollectedHeap::pending_card_num() {
2914 size_t extra_cards = 0;
2915 JavaThread *curr = Threads::first();
2916 while (curr != NULL) {
2917 DirtyCardQueue& dcq = curr->dirty_card_queue();
2918 extra_cards += dcq.size();
2919 curr = curr->next();
2920 }
2921 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2922 size_t buffer_size = dcqs.buffer_size();
2923 size_t buffer_num = dcqs.completed_buffers_num();
2924
2925 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2926 // in bytes - not the number of 'entries'. We need to convert
2927 // into a number of cards.
2928 return (buffer_size * buffer_num + extra_cards) / oopSize;
2929 }
2930
2931 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2932 private:
2933 size_t _total_humongous;
2934 size_t _candidate_humongous;
2935
2936 DirtyCardQueue _dcq;
2937
2938 // We don't nominate objects with many remembered set entries, on
2939 // the assumption that such objects are likely still live.
2940 bool is_remset_small(HeapRegion* region) const {
2941 HeapRegionRemSet* const rset = region->rem_set();
2942 return G1EagerReclaimHumongousObjectsWithStaleRefs
2943 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2944 : rset->is_empty();
2945 }
2946
2947 bool is_typeArray_region(HeapRegion* region) const {
2948 return oop(region->bottom())->is_typeArray();
2949 }
2950
2951 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2952 assert(region->is_starts_humongous(), "Must start a humongous object");
2953
2954 // Candidate selection must satisfy the following constraints
2955 // while concurrent marking is in progress:
2956 //
2957 // * In order to maintain SATB invariants, an object must not be
2958 // reclaimed if it was allocated before the start of marking and
2959 // has not had its references scanned. Such an object must have
2960 // its references (including type metadata) scanned to ensure no
2961 // live objects are missed by the marking process. Objects
2962 // allocated after the start of concurrent marking don't need to
2963 // be scanned.
2964 //
2965 // * An object must not be reclaimed if it is on the concurrent
2966 // mark stack. Objects allocated after the start of concurrent
2967 // marking are never pushed on the mark stack.
2968 //
2969 // Nominating only objects allocated after the start of concurrent
2970 // marking is sufficient to meet both constraints. This may miss
2971 // some objects that satisfy the constraints, but the marking data
2972 // structures don't support efficiently performing the needed
2973 // additional tests or scrubbing of the mark stack.
2974 //
2975 // However, we presently only nominate is_typeArray() objects.
2976 // A humongous object containing references induces remembered
2977 // set entries on other regions. In order to reclaim such an
2978 // object, those remembered sets would need to be cleaned up.
2979 //
2980 // We also treat is_typeArray() objects specially, allowing them
2981 // to be reclaimed even if allocated before the start of
2982 // concurrent mark. For this we rely on mark stack insertion to
2983 // exclude is_typeArray() objects, preventing reclaiming an object
2984 // that is in the mark stack. We also rely on the metadata for
2985 // such objects to be built-in and so ensured to be kept live.
2986 // Frequent allocation and drop of large binary blobs is an
2987 // important use case for eager reclaim, and this special handling
2988 // may reduce needed headroom.
2989
2990 return is_typeArray_region(region) && is_remset_small(region);
2991 }
2992
2993 public:
2994 RegisterHumongousWithInCSetFastTestClosure()
2995 : _total_humongous(0),
2996 _candidate_humongous(0),
2997 _dcq(&JavaThread::dirty_card_queue_set()) {
2998 }
2999
3000 virtual bool doHeapRegion(HeapRegion* r) {
3001 if (!r->is_starts_humongous()) {
3002 return false;
3003 }
3004 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3005
3006 bool is_candidate = humongous_region_is_candidate(g1h, r);
3007 uint rindex = r->hrm_index();
3008 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3009 if (is_candidate) {
3010 _candidate_humongous++;
3011 g1h->register_humongous_region_with_cset(rindex);
3012 // Is_candidate already filters out humongous object with large remembered sets.
3013 // If we have a humongous object with a few remembered sets, we simply flush these
3014 // remembered set entries into the DCQS. That will result in automatic
3015 // re-evaluation of their remembered set entries during the following evacuation
3016 // phase.
3017 if (!r->rem_set()->is_empty()) {
3018 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3019 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3020 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3021 HeapRegionRemSetIterator hrrs(r->rem_set());
3022 size_t card_index;
3023 while (hrrs.has_next(card_index)) {
3024 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3025 // The remembered set might contain references to already freed
3026 // regions. Filter out such entries to avoid failing card table
3027 // verification.
3028 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3029 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3030 *card_ptr = CardTableModRefBS::dirty_card_val();
3031 _dcq.enqueue(card_ptr);
3032 }
3033 }
3034 }
3035 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3036 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3037 hrrs.n_yielded(), r->rem_set()->occupied());
3038 r->rem_set()->clear_locked();
3039 }
3040 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3041 }
3042 _total_humongous++;
3043
3044 return false;
3045 }
3046
3047 size_t total_humongous() const { return _total_humongous; }
3048 size_t candidate_humongous() const { return _candidate_humongous; }
3049
3050 void flush_rem_set_entries() { _dcq.flush(); }
3051 };
3052
3053 void G1CollectedHeap::register_humongous_regions_with_cset() {
3054 if (!G1EagerReclaimHumongousObjects) {
3055 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3056 return;
3057 }
3058 double time = os::elapsed_counter();
3059
3060 // Collect reclaim candidate information and register candidates with cset.
3061 RegisterHumongousWithInCSetFastTestClosure cl;
3062 heap_region_iterate(&cl);
3063
3064 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3065 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3066 cl.total_humongous(),
3067 cl.candidate_humongous());
3068 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3069
3070 // Finally flush all remembered set entries to re-check into the global DCQS.
3071 cl.flush_rem_set_entries();
3072 }
3073
3074 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3075 public:
3076 bool doHeapRegion(HeapRegion* hr) {
3077 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3078 hr->verify_rem_set();
3079 }
3080 return false;
3081 }
3082 };
3083
3084 #ifdef ASSERT
3085 class VerifyCSetClosure: public HeapRegionClosure {
3086 public:
3087 bool doHeapRegion(HeapRegion* hr) {
3088 // Here we check that the CSet region's RSet is ready for parallel
3089 // iteration. The fields that we'll verify are only manipulated
3090 // when the region is part of a CSet and is collected. Afterwards,
3091 // we reset these fields when we clear the region's RSet (when the
3092 // region is freed) so they are ready when the region is
3093 // re-allocated. The only exception to this is if there's an
3094 // evacuation failure and instead of freeing the region we leave
3095 // it in the heap. In that case, we reset these fields during
3096 // evacuation failure handling.
3097 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3098
3099 // Here's a good place to add any other checks we'd like to
3100 // perform on CSet regions.
3101 return false;
3102 }
3103 };
3104 #endif // ASSERT
3105
3106 uint G1CollectedHeap::num_task_queues() const {
3107 return _task_queues->size();
3108 }
3109
3110 #if TASKQUEUE_STATS
3111 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3112 st->print_raw_cr("GC Task Stats");
3113 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3114 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3115 }
3116
3117 void G1CollectedHeap::print_taskqueue_stats() const {
3118 if (!log_is_enabled(Trace, gc, task, stats)) {
3119 return;
3120 }
3121 Log(gc, task, stats) log;
3122 ResourceMark rm;
3123 outputStream* st = log.trace_stream();
3124
3125 print_taskqueue_stats_hdr(st);
3126
3127 TaskQueueStats totals;
3128 const uint n = num_task_queues();
3129 for (uint i = 0; i < n; ++i) {
3130 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3131 totals += task_queue(i)->stats;
3132 }
3133 st->print_raw("tot "); totals.print(st); st->cr();
3134
3135 DEBUG_ONLY(totals.verify());
3136 }
3137
3138 void G1CollectedHeap::reset_taskqueue_stats() {
3139 const uint n = num_task_queues();
3140 for (uint i = 0; i < n; ++i) {
3141 task_queue(i)->stats.reset();
3142 }
3143 }
3144 #endif // TASKQUEUE_STATS
3145
3146 void G1CollectedHeap::wait_for_root_region_scanning() {
3147 double scan_wait_start = os::elapsedTime();
3148 // We have to wait until the CM threads finish scanning the
3149 // root regions as it's the only way to ensure that all the
3150 // objects on them have been correctly scanned before we start
3151 // moving them during the GC.
3152 bool waited = _cm->root_regions()->wait_until_scan_finished();
3153 double wait_time_ms = 0.0;
3154 if (waited) {
3155 double scan_wait_end = os::elapsedTime();
3156 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3157 }
3158 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3159 }
3160
3161 bool
3162 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3163 assert_at_safepoint(true /* should_be_vm_thread */);
3164 guarantee(!is_gc_active(), "collection is not reentrant");
3165
3166 if (GCLocker::check_active_before_gc()) {
3167 return false;
3168 }
3169
3170 _gc_timer_stw->register_gc_start();
3171
3172 GCIdMark gc_id_mark;
3173 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3174
3175 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3176 ResourceMark rm;
3177
3178 wait_for_root_region_scanning();
3179
3180 print_heap_before_gc();
3181 print_heap_regions();
3182 trace_heap_before_gc(_gc_tracer_stw);
3183
3184 _verifier->verify_region_sets_optional();
3185 _verifier->verify_dirty_young_regions();
3186
3187 // We should not be doing initial mark unless the conc mark thread is running
3188 if (!_cmThread->should_terminate()) {
3189 // This call will decide whether this pause is an initial-mark
3190 // pause. If it is, during_initial_mark_pause() will return true
3191 // for the duration of this pause.
3192 g1_policy()->decide_on_conc_mark_initiation();
3193 }
3194
3195 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3196 assert(!collector_state()->during_initial_mark_pause() ||
3197 collector_state()->gcs_are_young(), "sanity");
3198
3199 // We also do not allow mixed GCs during marking.
3200 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3201
3202 // Record whether this pause is an initial mark. When the current
3203 // thread has completed its logging output and it's safe to signal
3204 // the CM thread, the flag's value in the policy has been reset.
3205 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3206
3207 // Inner scope for scope based logging, timers, and stats collection
3208 {
3209 EvacuationInfo evacuation_info;
3210
3211 if (collector_state()->during_initial_mark_pause()) {
3212 // We are about to start a marking cycle, so we increment the
3213 // full collection counter.
3214 increment_old_marking_cycles_started();
3215 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3216 }
3217
3218 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3219
3220 GCTraceCPUTime tcpu;
3221
3222 FormatBuffer<> gc_string("Pause ");
3223 if (collector_state()->during_initial_mark_pause()) {
3224 gc_string.append("Initial Mark");
3225 } else if (collector_state()->gcs_are_young()) {
3226 gc_string.append("Young");
3227 } else {
3228 gc_string.append("Mixed");
3229 }
3230 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3231
3232 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3233 workers()->active_workers(),
3234 Threads::number_of_non_daemon_threads());
3235 workers()->set_active_workers(active_workers);
3236
3237 g1_policy()->note_gc_start();
3238
3239 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3240 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3241
3242 // If the secondary_free_list is not empty, append it to the
3243 // free_list. No need to wait for the cleanup operation to finish;
3244 // the region allocation code will check the secondary_free_list
3245 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3246 // set, skip this step so that the region allocation code has to
3247 // get entries from the secondary_free_list.
3248 if (!G1StressConcRegionFreeing) {
3249 append_secondary_free_list_if_not_empty_with_lock();
3250 }
3251
3252 G1HeapTransition heap_transition(this);
3253 size_t heap_used_bytes_before_gc = used();
3254
3255 assert(check_young_list_well_formed(), "young list should be well formed");
3256
3257 // Don't dynamically change the number of GC threads this early. A value of
3258 // 0 is used to indicate serial work. When parallel work is done,
3259 // it will be set.
3260
3261 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3262 IsGCActiveMark x;
3263
3264 gc_prologue(false);
3265 increment_total_collections(false /* full gc */);
3266 increment_gc_time_stamp();
3267
3268 if (VerifyRememberedSets) {
3269 log_info(gc, verify)("[Verifying RemSets before GC]");
3270 VerifyRegionRemSetClosure v_cl;
3271 heap_region_iterate(&v_cl);
3272 }
3273
3274 _verifier->verify_before_gc();
3275
3276 _verifier->check_bitmaps("GC Start");
3277
3278 #if defined(COMPILER2) || INCLUDE_JVMCI
3279 DerivedPointerTable::clear();
3280 #endif
3281
3282 // Please see comment in g1CollectedHeap.hpp and
3283 // G1CollectedHeap::ref_processing_init() to see how
3284 // reference processing currently works in G1.
3285
3286 // Enable discovery in the STW reference processor
3287 if (g1_policy()->should_process_references()) {
3288 ref_processor_stw()->enable_discovery();
3289 } else {
3290 ref_processor_stw()->disable_discovery();
3291 }
3292
3293 {
3294 // We want to temporarily turn off discovery by the
3295 // CM ref processor, if necessary, and turn it back on
3296 // on again later if we do. Using a scoped
3297 // NoRefDiscovery object will do this.
3298 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3299
3300 // Forget the current alloc region (we might even choose it to be part
3301 // of the collection set!).
3302 _allocator->release_mutator_alloc_region();
3303
3304 // This timing is only used by the ergonomics to handle our pause target.
3305 // It is unclear why this should not include the full pause. We will
3306 // investigate this in CR 7178365.
3307 //
3308 // Preserving the old comment here if that helps the investigation:
3309 //
3310 // The elapsed time induced by the start time below deliberately elides
3311 // the possible verification above.
3312 double sample_start_time_sec = os::elapsedTime();
3313
3314 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3315
3316 if (collector_state()->during_initial_mark_pause()) {
3317 concurrent_mark()->checkpointRootsInitialPre();
3318 }
3319
3320 g1_policy()->finalize_collection_set(target_pause_time_ms);
3321
3322 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3323
3324 // Make sure the remembered sets are up to date. This needs to be
3325 // done before register_humongous_regions_with_cset(), because the
3326 // remembered sets are used there to choose eager reclaim candidates.
3327 // If the remembered sets are not up to date we might miss some
3328 // entries that need to be handled.
3329 g1_rem_set()->cleanupHRRS();
3330
3331 register_humongous_regions_with_cset();
3332
3333 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3334
3335 _cm->note_start_of_gc();
3336 // We call this after finalize_cset() to
3337 // ensure that the CSet has been finalized.
3338 _cm->verify_no_cset_oops();
3339
3340 if (_hr_printer.is_active()) {
3341 HeapRegion* hr = collection_set()->head();
3342 while (hr != NULL) {
3343 _hr_printer.cset(hr);
3344 hr = hr->next_in_collection_set();
3345 }
3346 }
3347
3348 #ifdef ASSERT
3349 VerifyCSetClosure cl;
3350 collection_set_iterate(&cl);
3351 #endif // ASSERT
3352
3353 // Initialize the GC alloc regions.
3354 _allocator->init_gc_alloc_regions(evacuation_info);
3355
3356 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3357 pre_evacuate_collection_set();
3358
3359 // Actually do the work...
3360 evacuate_collection_set(evacuation_info, &per_thread_states);
3361
3362 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3363
3364 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3365 free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3366
3367 eagerly_reclaim_humongous_regions();
3368
3369 collection_set()->clear_head();
3370
3371 record_obj_copy_mem_stats();
3372 _survivor_evac_stats.adjust_desired_plab_sz();
3373 _old_evac_stats.adjust_desired_plab_sz();
3374
3375 // Start a new incremental collection set for the next pause.
3376 collection_set()->start_incremental_building();
3377
3378 clear_cset_fast_test();
3379
3380 // Don't check the whole heap at this point as the
3381 // GC alloc regions from this pause have been tagged
3382 // as survivors and moved on to the survivor list.
3383 // Survivor regions will fail the !is_young() check.
3384 assert(check_young_list_empty(false /* check_heap */),
3385 "young list should be empty");
3386
3387 _young_list->reset_auxilary_lists();
3388
3389 if (evacuation_failed()) {
3390 set_used(recalculate_used());
3391 if (_archive_allocator != NULL) {
3392 _archive_allocator->clear_used();
3393 }
3394 for (uint i = 0; i < ParallelGCThreads; i++) {
3395 if (_evacuation_failed_info_array[i].has_failed()) {
3396 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3397 }
3398 }
3399 } else {
3400 // The "used" of the the collection set have already been subtracted
3401 // when they were freed. Add in the bytes evacuated.
3402 increase_used(g1_policy()->bytes_copied_during_gc());
3403 }
3404
3405 if (collector_state()->during_initial_mark_pause()) {
3406 // We have to do this before we notify the CM threads that
3407 // they can start working to make sure that all the
3408 // appropriate initialization is done on the CM object.
3409 concurrent_mark()->checkpointRootsInitialPost();
3410 collector_state()->set_mark_in_progress(true);
3411 // Note that we don't actually trigger the CM thread at
3412 // this point. We do that later when we're sure that
3413 // the current thread has completed its logging output.
3414 }
3415
3416 allocate_dummy_regions();
3417
3418 _allocator->init_mutator_alloc_region();
3419
3420 {
3421 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3422 if (expand_bytes > 0) {
3423 size_t bytes_before = capacity();
3424 // No need for an ergo logging here,
3425 // expansion_amount() does this when it returns a value > 0.
3426 double expand_ms;
3427 if (!expand(expand_bytes, &expand_ms)) {
3428 // We failed to expand the heap. Cannot do anything about it.
3429 }
3430 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3431 }
3432 }
3433
3434 // We redo the verification but now wrt to the new CSet which
3435 // has just got initialized after the previous CSet was freed.
3436 _cm->verify_no_cset_oops();
3437 _cm->note_end_of_gc();
3438
3439 // This timing is only used by the ergonomics to handle our pause target.
3440 // It is unclear why this should not include the full pause. We will
3441 // investigate this in CR 7178365.
3442 double sample_end_time_sec = os::elapsedTime();
3443 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3444 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3445 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3446
3447 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3448 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3449
3450 MemoryService::track_memory_usage();
3451
3452 // In prepare_for_verify() below we'll need to scan the deferred
3453 // update buffers to bring the RSets up-to-date if
3454 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3455 // the update buffers we'll probably need to scan cards on the
3456 // regions we just allocated to (i.e., the GC alloc
3457 // regions). However, during the last GC we called
3458 // set_saved_mark() on all the GC alloc regions, so card
3459 // scanning might skip the [saved_mark_word()...top()] area of
3460 // those regions (i.e., the area we allocated objects into
3461 // during the last GC). But it shouldn't. Given that
3462 // saved_mark_word() is conditional on whether the GC time stamp
3463 // on the region is current or not, by incrementing the GC time
3464 // stamp here we invalidate all the GC time stamps on all the
3465 // regions and saved_mark_word() will simply return top() for
3466 // all the regions. This is a nicer way of ensuring this rather
3467 // than iterating over the regions and fixing them. In fact, the
3468 // GC time stamp increment here also ensures that
3469 // saved_mark_word() will return top() between pauses, i.e.,
3470 // during concurrent refinement. So we don't need the
3471 // is_gc_active() check to decided which top to use when
3472 // scanning cards (see CR 7039627).
3473 increment_gc_time_stamp();
3474
3475 if (VerifyRememberedSets) {
3476 log_info(gc, verify)("[Verifying RemSets after GC]");
3477 VerifyRegionRemSetClosure v_cl;
3478 heap_region_iterate(&v_cl);
3479 }
3480
3481 _verifier->verify_after_gc();
3482 _verifier->check_bitmaps("GC End");
3483
3484 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3485 ref_processor_stw()->verify_no_references_recorded();
3486
3487 // CM reference discovery will be re-enabled if necessary.
3488 }
3489
3490 #ifdef TRACESPINNING
3491 ParallelTaskTerminator::print_termination_counts();
3492 #endif
3493
3494 gc_epilogue(false);
3495 }
3496
3497 // Print the remainder of the GC log output.
3498 if (evacuation_failed()) {
3499 log_info(gc)("To-space exhausted");
3500 }
3501
3502 g1_policy()->print_phases();
3503 heap_transition.print();
3504
3505 // It is not yet to safe to tell the concurrent mark to
3506 // start as we have some optional output below. We don't want the
3507 // output from the concurrent mark thread interfering with this
3508 // logging output either.
3509
3510 _hrm.verify_optional();
3511 _verifier->verify_region_sets_optional();
3512
3513 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3514 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3515
3516 print_heap_after_gc();
3517 print_heap_regions();
3518 trace_heap_after_gc(_gc_tracer_stw);
3519
3520 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3521 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3522 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3523 // before any GC notifications are raised.
3524 g1mm()->update_sizes();
3525
3526 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3527 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3528 _gc_timer_stw->register_gc_end();
3529 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3530 }
3531 // It should now be safe to tell the concurrent mark thread to start
3532 // without its logging output interfering with the logging output
3533 // that came from the pause.
3534
3535 if (should_start_conc_mark) {
3536 // CAUTION: after the doConcurrentMark() call below,
3537 // the concurrent marking thread(s) could be running
3538 // concurrently with us. Make sure that anything after
3539 // this point does not assume that we are the only GC thread
3540 // running. Note: of course, the actual marking work will
3541 // not start until the safepoint itself is released in
3542 // SuspendibleThreadSet::desynchronize().
3543 doConcurrentMark();
3544 }
3545
3546 return true;
3547 }
3548
3549 void G1CollectedHeap::restore_preserved_marks() {
3550 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3551 workers()->run_task(&rpm_task);
3552 }
3553
3554 void G1CollectedHeap::remove_self_forwarding_pointers() {
3555 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3556 workers()->run_task(&rsfp_task);
3557 }
3558
3559 void G1CollectedHeap::restore_after_evac_failure() {
3560 double remove_self_forwards_start = os::elapsedTime();
3561
3562 remove_self_forwarding_pointers();
3563 restore_preserved_marks();
3564
3565 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3566 }
3567
3568 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3569 if (!_evacuation_failed) {
3570 _evacuation_failed = true;
3571 }
3572
3573 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3574
3575 // We want to call the "for_promotion_failure" version only in the
3576 // case of a promotion failure.
3577 if (m->must_be_preserved_for_promotion_failure(obj)) {
3578 OopAndMarkOop elem(obj, m);
3579 _preserved_objs[worker_id].push(elem);
3580 }
3581 }
3582
3583 bool G1ParEvacuateFollowersClosure::offer_termination() {
3584 G1ParScanThreadState* const pss = par_scan_state();
3585 start_term_time();
3586 const bool res = terminator()->offer_termination();
3587 end_term_time();
3588 return res;
3589 }
3590
3591 void G1ParEvacuateFollowersClosure::do_void() {
3592 G1ParScanThreadState* const pss = par_scan_state();
3593 pss->trim_queue();
3594 do {
3595 pss->steal_and_trim_queue(queues());
3596 } while (!offer_termination());
3597 }
3598
3599 class G1ParTask : public AbstractGangTask {
3600 protected:
3601 G1CollectedHeap* _g1h;
3602 G1ParScanThreadStateSet* _pss;
3603 RefToScanQueueSet* _queues;
3604 G1RootProcessor* _root_processor;
3605 ParallelTaskTerminator _terminator;
3606 uint _n_workers;
3607
3608 public:
3609 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3610 : AbstractGangTask("G1 collection"),
3611 _g1h(g1h),
3612 _pss(per_thread_states),
3613 _queues(task_queues),
3614 _root_processor(root_processor),
3615 _terminator(n_workers, _queues),
3616 _n_workers(n_workers)
3617 {}
3618
3619 void work(uint worker_id) {
3620 if (worker_id >= _n_workers) return; // no work needed this round
3621
3622 double start_sec = os::elapsedTime();
3623 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3624
3625 {
3626 ResourceMark rm;
3627 HandleMark hm;
3628
3629 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3630
3631 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3632 pss->set_ref_processor(rp);
3633
3634 double start_strong_roots_sec = os::elapsedTime();
3635
3636 _root_processor->evacuate_roots(pss->closures(), worker_id);
3637
3638 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3639
3640 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3641 // treating the nmethods visited to act as roots for concurrent marking.
3642 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3643 // objects copied by the current evacuation.
3644 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3645 pss->closures()->weak_codeblobs(),
3646 worker_id);
3647
3648 _pss->add_cards_scanned(worker_id, cards_scanned);
3649
3650 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3651
3652 double term_sec = 0.0;
3653 size_t evac_term_attempts = 0;
3654 {
3655 double start = os::elapsedTime();
3656 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3657 evac.do_void();
3658
3659 evac_term_attempts = evac.term_attempts();
3660 term_sec = evac.term_time();
3661 double elapsed_sec = os::elapsedTime() - start;
3662 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3663 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3664 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3665 }
3666
3667 assert(pss->queue_is_empty(), "should be empty");
3668
3669 if (log_is_enabled(Debug, gc, task, stats)) {
3670 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3671 size_t lab_waste;
3672 size_t lab_undo_waste;
3673 pss->waste(lab_waste, lab_undo_waste);
3674 _g1h->print_termination_stats(worker_id,
3675 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3676 strong_roots_sec * 1000.0, /* strong roots time */
3677 term_sec * 1000.0, /* evac term time */
3678 evac_term_attempts, /* evac term attempts */
3679 lab_waste, /* alloc buffer waste */
3680 lab_undo_waste /* undo waste */
3681 );
3682 }
3683
3684 // Close the inner scope so that the ResourceMark and HandleMark
3685 // destructors are executed here and are included as part of the
3686 // "GC Worker Time".
3687 }
3688 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3689 }
3690 };
3691
3692 void G1CollectedHeap::print_termination_stats_hdr() {
3693 log_debug(gc, task, stats)("GC Termination Stats");
3694 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3695 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3696 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3697 }
3698
3699 void G1CollectedHeap::print_termination_stats(uint worker_id,
3700 double elapsed_ms,
3701 double strong_roots_ms,
3702 double term_ms,
3703 size_t term_attempts,
3704 size_t alloc_buffer_waste,
3705 size_t undo_waste) const {
3706 log_debug(gc, task, stats)
3707 ("%3d %9.2f %9.2f %6.2f "
3708 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3709 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3710 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3711 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3712 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3713 alloc_buffer_waste * HeapWordSize / K,
3714 undo_waste * HeapWordSize / K);
3715 }
3716
3717 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3718 private:
3719 BoolObjectClosure* _is_alive;
3720 int _initial_string_table_size;
3721 int _initial_symbol_table_size;
3722
3723 bool _process_strings;
3724 int _strings_processed;
3725 int _strings_removed;
3726
3727 bool _process_symbols;
3728 int _symbols_processed;
3729 int _symbols_removed;
3730
3731 public:
3732 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3733 AbstractGangTask("String/Symbol Unlinking"),
3734 _is_alive(is_alive),
3735 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3736 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3737
3738 _initial_string_table_size = StringTable::the_table()->table_size();
3739 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3740 if (process_strings) {
3741 StringTable::clear_parallel_claimed_index();
3742 }
3743 if (process_symbols) {
3744 SymbolTable::clear_parallel_claimed_index();
3745 }
3746 }
3747
3748 ~G1StringSymbolTableUnlinkTask() {
3749 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3750 "claim value %d after unlink less than initial string table size %d",
3751 StringTable::parallel_claimed_index(), _initial_string_table_size);
3752 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3753 "claim value %d after unlink less than initial symbol table size %d",
3754 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3755
3756 log_info(gc, stringtable)(
3757 "Cleaned string and symbol table, "
3758 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3759 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3760 strings_processed(), strings_removed(),
3761 symbols_processed(), symbols_removed());
3762 }
3763
3764 void work(uint worker_id) {
3765 int strings_processed = 0;
3766 int strings_removed = 0;
3767 int symbols_processed = 0;
3768 int symbols_removed = 0;
3769 if (_process_strings) {
3770 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3771 Atomic::add(strings_processed, &_strings_processed);
3772 Atomic::add(strings_removed, &_strings_removed);
3773 }
3774 if (_process_symbols) {
3775 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3776 Atomic::add(symbols_processed, &_symbols_processed);
3777 Atomic::add(symbols_removed, &_symbols_removed);
3778 }
3779 }
3780
3781 size_t strings_processed() const { return (size_t)_strings_processed; }
3782 size_t strings_removed() const { return (size_t)_strings_removed; }
3783
3784 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3785 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3786 };
3787
3788 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3789 private:
3790 static Monitor* _lock;
3791
3792 BoolObjectClosure* const _is_alive;
3793 const bool _unloading_occurred;
3794 const uint _num_workers;
3795
3796 // Variables used to claim nmethods.
3797 nmethod* _first_nmethod;
3798 volatile nmethod* _claimed_nmethod;
3799
3800 // The list of nmethods that need to be processed by the second pass.
3801 volatile nmethod* _postponed_list;
3802 volatile uint _num_entered_barrier;
3803
3804 public:
3805 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3806 _is_alive(is_alive),
3807 _unloading_occurred(unloading_occurred),
3808 _num_workers(num_workers),
3809 _first_nmethod(NULL),
3810 _claimed_nmethod(NULL),
3811 _postponed_list(NULL),
3812 _num_entered_barrier(0)
3813 {
3814 nmethod::increase_unloading_clock();
3815 // Get first alive nmethod
3816 NMethodIterator iter = NMethodIterator();
3817 if(iter.next_alive()) {
3818 _first_nmethod = iter.method();
3819 }
3820 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3821 }
3822
3823 ~G1CodeCacheUnloadingTask() {
3824 CodeCache::verify_clean_inline_caches();
3825
3826 CodeCache::set_needs_cache_clean(false);
3827 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3828
3829 CodeCache::verify_icholder_relocations();
3830 }
3831
3832 private:
3833 void add_to_postponed_list(nmethod* nm) {
3834 nmethod* old;
3835 do {
3836 old = (nmethod*)_postponed_list;
3837 nm->set_unloading_next(old);
3838 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3839 }
3840
3841 void clean_nmethod(nmethod* nm) {
3842 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3843
3844 if (postponed) {
3845 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3846 add_to_postponed_list(nm);
3847 }
3848
3849 // Mark that this thread has been cleaned/unloaded.
3850 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3851 nm->set_unloading_clock(nmethod::global_unloading_clock());
3852 }
3853
3854 void clean_nmethod_postponed(nmethod* nm) {
3855 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3856 }
3857
3858 static const int MaxClaimNmethods = 16;
3859
3860 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3861 nmethod* first;
3862 NMethodIterator last;
3863
3864 do {
3865 *num_claimed_nmethods = 0;
3866
3867 first = (nmethod*)_claimed_nmethod;
3868 last = NMethodIterator(first);
3869
3870 if (first != NULL) {
3871
3872 for (int i = 0; i < MaxClaimNmethods; i++) {
3873 if (!last.next_alive()) {
3874 break;
3875 }
3876 claimed_nmethods[i] = last.method();
3877 (*num_claimed_nmethods)++;
3878 }
3879 }
3880
3881 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3882 }
3883
3884 nmethod* claim_postponed_nmethod() {
3885 nmethod* claim;
3886 nmethod* next;
3887
3888 do {
3889 claim = (nmethod*)_postponed_list;
3890 if (claim == NULL) {
3891 return NULL;
3892 }
3893
3894 next = claim->unloading_next();
3895
3896 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3897
3898 return claim;
3899 }
3900
3901 public:
3902 // Mark that we're done with the first pass of nmethod cleaning.
3903 void barrier_mark(uint worker_id) {
3904 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3905 _num_entered_barrier++;
3906 if (_num_entered_barrier == _num_workers) {
3907 ml.notify_all();
3908 }
3909 }
3910
3911 // See if we have to wait for the other workers to
3912 // finish their first-pass nmethod cleaning work.
3913 void barrier_wait(uint worker_id) {
3914 if (_num_entered_barrier < _num_workers) {
3915 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3916 while (_num_entered_barrier < _num_workers) {
3917 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3918 }
3919 }
3920 }
3921
3922 // Cleaning and unloading of nmethods. Some work has to be postponed
3923 // to the second pass, when we know which nmethods survive.
3924 void work_first_pass(uint worker_id) {
3925 // The first nmethods is claimed by the first worker.
3926 if (worker_id == 0 && _first_nmethod != NULL) {
3927 clean_nmethod(_first_nmethod);
3928 _first_nmethod = NULL;
3929 }
3930
3931 int num_claimed_nmethods;
3932 nmethod* claimed_nmethods[MaxClaimNmethods];
3933
3934 while (true) {
3935 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3936
3937 if (num_claimed_nmethods == 0) {
3938 break;
3939 }
3940
3941 for (int i = 0; i < num_claimed_nmethods; i++) {
3942 clean_nmethod(claimed_nmethods[i]);
3943 }
3944 }
3945 }
3946
3947 void work_second_pass(uint worker_id) {
3948 nmethod* nm;
3949 // Take care of postponed nmethods.
3950 while ((nm = claim_postponed_nmethod()) != NULL) {
3951 clean_nmethod_postponed(nm);
3952 }
3953 }
3954 };
3955
3956 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3957
3958 class G1KlassCleaningTask : public StackObj {
3959 BoolObjectClosure* _is_alive;
3960 volatile jint _clean_klass_tree_claimed;
3961 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3962
3963 public:
3964 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3965 _is_alive(is_alive),
3966 _clean_klass_tree_claimed(0),
3967 _klass_iterator() {
3968 }
3969
3970 private:
3971 bool claim_clean_klass_tree_task() {
3972 if (_clean_klass_tree_claimed) {
3973 return false;
3974 }
3975
3976 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3977 }
3978
3979 InstanceKlass* claim_next_klass() {
3980 Klass* klass;
3981 do {
3982 klass =_klass_iterator.next_klass();
3983 } while (klass != NULL && !klass->is_instance_klass());
3984
3985 // this can be null so don't call InstanceKlass::cast
3986 return static_cast<InstanceKlass*>(klass);
3987 }
3988
3989 public:
3990
3991 void clean_klass(InstanceKlass* ik) {
3992 ik->clean_weak_instanceklass_links(_is_alive);
3993 }
3994
3995 void work() {
3996 ResourceMark rm;
3997
3998 // One worker will clean the subklass/sibling klass tree.
3999 if (claim_clean_klass_tree_task()) {
4000 Klass::clean_subklass_tree(_is_alive);
4001 }
4002
4003 // All workers will help cleaning the classes,
4004 InstanceKlass* klass;
4005 while ((klass = claim_next_klass()) != NULL) {
4006 clean_klass(klass);
4007 }
4008 }
4009 };
4010
4011 // To minimize the remark pause times, the tasks below are done in parallel.
4012 class G1ParallelCleaningTask : public AbstractGangTask {
4013 private:
4014 G1StringSymbolTableUnlinkTask _string_symbol_task;
4015 G1CodeCacheUnloadingTask _code_cache_task;
4016 G1KlassCleaningTask _klass_cleaning_task;
4017
4018 public:
4019 // The constructor is run in the VMThread.
4020 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4021 AbstractGangTask("Parallel Cleaning"),
4022 _string_symbol_task(is_alive, process_strings, process_symbols),
4023 _code_cache_task(num_workers, is_alive, unloading_occurred),
4024 _klass_cleaning_task(is_alive) {
4025 }
4026
4027 // The parallel work done by all worker threads.
4028 void work(uint worker_id) {
4029 // Do first pass of code cache cleaning.
4030 _code_cache_task.work_first_pass(worker_id);
4031
4032 // Let the threads mark that the first pass is done.
4033 _code_cache_task.barrier_mark(worker_id);
4034
4035 // Clean the Strings and Symbols.
4036 _string_symbol_task.work(worker_id);
4037
4038 // Wait for all workers to finish the first code cache cleaning pass.
4039 _code_cache_task.barrier_wait(worker_id);
4040
4041 // Do the second code cache cleaning work, which realize on
4042 // the liveness information gathered during the first pass.
4043 _code_cache_task.work_second_pass(worker_id);
4044
4045 // Clean all klasses that were not unloaded.
4046 _klass_cleaning_task.work();
4047 }
4048 };
4049
4050
4051 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4052 bool process_strings,
4053 bool process_symbols,
4054 bool class_unloading_occurred) {
4055 uint n_workers = workers()->active_workers();
4056
4057 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4058 n_workers, class_unloading_occurred);
4059 workers()->run_task(&g1_unlink_task);
4060 }
4061
4062 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4063 bool process_strings, bool process_symbols) {
4064 { // Timing scope
4065 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4066 workers()->run_task(&g1_unlink_task);
4067 }
4068 }
4069
4070 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4071 private:
4072 DirtyCardQueueSet* _queue;
4073 G1CollectedHeap* _g1h;
4074 public:
4075 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4076 _queue(queue), _g1h(g1h) { }
4077
4078 virtual void work(uint worker_id) {
4079 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4080 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4081
4082 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4083 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4084
4085 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4086 }
4087 };
4088
4089 void G1CollectedHeap::redirty_logged_cards() {
4090 double redirty_logged_cards_start = os::elapsedTime();
4091
4092 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4093 dirty_card_queue_set().reset_for_par_iteration();
4094 workers()->run_task(&redirty_task);
4095
4096 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4097 dcq.merge_bufferlists(&dirty_card_queue_set());
4098 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4099
4100 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4101 }
4102
4103 // Weak Reference Processing support
4104
4105 // An always "is_alive" closure that is used to preserve referents.
4106 // If the object is non-null then it's alive. Used in the preservation
4107 // of referent objects that are pointed to by reference objects
4108 // discovered by the CM ref processor.
4109 class G1AlwaysAliveClosure: public BoolObjectClosure {
4110 G1CollectedHeap* _g1;
4111 public:
4112 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4113 bool do_object_b(oop p) {
4114 if (p != NULL) {
4115 return true;
4116 }
4117 return false;
4118 }
4119 };
4120
4121 bool G1STWIsAliveClosure::do_object_b(oop p) {
4122 // An object is reachable if it is outside the collection set,
4123 // or is inside and copied.
4124 return !_g1->is_in_cset(p) || p->is_forwarded();
4125 }
4126
4127 // Non Copying Keep Alive closure
4128 class G1KeepAliveClosure: public OopClosure {
4129 G1CollectedHeap* _g1;
4130 public:
4131 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4132 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4133 void do_oop(oop* p) {
4134 oop obj = *p;
4135 assert(obj != NULL, "the caller should have filtered out NULL values");
4136
4137 const InCSetState cset_state = _g1->in_cset_state(obj);
4138 if (!cset_state.is_in_cset_or_humongous()) {
4139 return;
4140 }
4141 if (cset_state.is_in_cset()) {
4142 assert( obj->is_forwarded(), "invariant" );
4143 *p = obj->forwardee();
4144 } else {
4145 assert(!obj->is_forwarded(), "invariant" );
4146 assert(cset_state.is_humongous(),
4147 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4148 _g1->set_humongous_is_live(obj);
4149 }
4150 }
4151 };
4152
4153 // Copying Keep Alive closure - can be called from both
4154 // serial and parallel code as long as different worker
4155 // threads utilize different G1ParScanThreadState instances
4156 // and different queues.
4157
4158 class G1CopyingKeepAliveClosure: public OopClosure {
4159 G1CollectedHeap* _g1h;
4160 OopClosure* _copy_non_heap_obj_cl;
4161 G1ParScanThreadState* _par_scan_state;
4162
4163 public:
4164 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4165 OopClosure* non_heap_obj_cl,
4166 G1ParScanThreadState* pss):
4167 _g1h(g1h),
4168 _copy_non_heap_obj_cl(non_heap_obj_cl),
4169 _par_scan_state(pss)
4170 {}
4171
4172 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4173 virtual void do_oop( oop* p) { do_oop_work(p); }
4174
4175 template <class T> void do_oop_work(T* p) {
4176 oop obj = oopDesc::load_decode_heap_oop(p);
4177
4178 if (_g1h->is_in_cset_or_humongous(obj)) {
4179 // If the referent object has been forwarded (either copied
4180 // to a new location or to itself in the event of an
4181 // evacuation failure) then we need to update the reference
4182 // field and, if both reference and referent are in the G1
4183 // heap, update the RSet for the referent.
4184 //
4185 // If the referent has not been forwarded then we have to keep
4186 // it alive by policy. Therefore we have copy the referent.
4187 //
4188 // If the reference field is in the G1 heap then we can push
4189 // on the PSS queue. When the queue is drained (after each
4190 // phase of reference processing) the object and it's followers
4191 // will be copied, the reference field set to point to the
4192 // new location, and the RSet updated. Otherwise we need to
4193 // use the the non-heap or metadata closures directly to copy
4194 // the referent object and update the pointer, while avoiding
4195 // updating the RSet.
4196
4197 if (_g1h->is_in_g1_reserved(p)) {
4198 _par_scan_state->push_on_queue(p);
4199 } else {
4200 assert(!Metaspace::contains((const void*)p),
4201 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4202 _copy_non_heap_obj_cl->do_oop(p);
4203 }
4204 }
4205 }
4206 };
4207
4208 // Serial drain queue closure. Called as the 'complete_gc'
4209 // closure for each discovered list in some of the
4210 // reference processing phases.
4211
4212 class G1STWDrainQueueClosure: public VoidClosure {
4213 protected:
4214 G1CollectedHeap* _g1h;
4215 G1ParScanThreadState* _par_scan_state;
4216
4217 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4218
4219 public:
4220 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4221 _g1h(g1h),
4222 _par_scan_state(pss)
4223 { }
4224
4225 void do_void() {
4226 G1ParScanThreadState* const pss = par_scan_state();
4227 pss->trim_queue();
4228 }
4229 };
4230
4231 // Parallel Reference Processing closures
4232
4233 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4234 // processing during G1 evacuation pauses.
4235
4236 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4237 private:
4238 G1CollectedHeap* _g1h;
4239 G1ParScanThreadStateSet* _pss;
4240 RefToScanQueueSet* _queues;
4241 WorkGang* _workers;
4242 uint _active_workers;
4243
4244 public:
4245 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4246 G1ParScanThreadStateSet* per_thread_states,
4247 WorkGang* workers,
4248 RefToScanQueueSet *task_queues,
4249 uint n_workers) :
4250 _g1h(g1h),
4251 _pss(per_thread_states),
4252 _queues(task_queues),
4253 _workers(workers),
4254 _active_workers(n_workers)
4255 {
4256 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4257 }
4258
4259 // Executes the given task using concurrent marking worker threads.
4260 virtual void execute(ProcessTask& task);
4261 virtual void execute(EnqueueTask& task);
4262 };
4263
4264 // Gang task for possibly parallel reference processing
4265
4266 class G1STWRefProcTaskProxy: public AbstractGangTask {
4267 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4268 ProcessTask& _proc_task;
4269 G1CollectedHeap* _g1h;
4270 G1ParScanThreadStateSet* _pss;
4271 RefToScanQueueSet* _task_queues;
4272 ParallelTaskTerminator* _terminator;
4273
4274 public:
4275 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4276 G1CollectedHeap* g1h,
4277 G1ParScanThreadStateSet* per_thread_states,
4278 RefToScanQueueSet *task_queues,
4279 ParallelTaskTerminator* terminator) :
4280 AbstractGangTask("Process reference objects in parallel"),
4281 _proc_task(proc_task),
4282 _g1h(g1h),
4283 _pss(per_thread_states),
4284 _task_queues(task_queues),
4285 _terminator(terminator)
4286 {}
4287
4288 virtual void work(uint worker_id) {
4289 // The reference processing task executed by a single worker.
4290 ResourceMark rm;
4291 HandleMark hm;
4292
4293 G1STWIsAliveClosure is_alive(_g1h);
4294
4295 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4296 pss->set_ref_processor(NULL);
4297
4298 // Keep alive closure.
4299 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4300
4301 // Complete GC closure
4302 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4303
4304 // Call the reference processing task's work routine.
4305 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4306
4307 // Note we cannot assert that the refs array is empty here as not all
4308 // of the processing tasks (specifically phase2 - pp2_work) execute
4309 // the complete_gc closure (which ordinarily would drain the queue) so
4310 // the queue may not be empty.
4311 }
4312 };
4313
4314 // Driver routine for parallel reference processing.
4315 // Creates an instance of the ref processing gang
4316 // task and has the worker threads execute it.
4317 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4318 assert(_workers != NULL, "Need parallel worker threads.");
4319
4320 ParallelTaskTerminator terminator(_active_workers, _queues);
4321 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4322
4323 _workers->run_task(&proc_task_proxy);
4324 }
4325
4326 // Gang task for parallel reference enqueueing.
4327
4328 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4329 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4330 EnqueueTask& _enq_task;
4331
4332 public:
4333 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4334 AbstractGangTask("Enqueue reference objects in parallel"),
4335 _enq_task(enq_task)
4336 { }
4337
4338 virtual void work(uint worker_id) {
4339 _enq_task.work(worker_id);
4340 }
4341 };
4342
4343 // Driver routine for parallel reference enqueueing.
4344 // Creates an instance of the ref enqueueing gang
4345 // task and has the worker threads execute it.
4346
4347 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4348 assert(_workers != NULL, "Need parallel worker threads.");
4349
4350 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4351
4352 _workers->run_task(&enq_task_proxy);
4353 }
4354
4355 // End of weak reference support closures
4356
4357 // Abstract task used to preserve (i.e. copy) any referent objects
4358 // that are in the collection set and are pointed to by reference
4359 // objects discovered by the CM ref processor.
4360
4361 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4362 protected:
4363 G1CollectedHeap* _g1h;
4364 G1ParScanThreadStateSet* _pss;
4365 RefToScanQueueSet* _queues;
4366 ParallelTaskTerminator _terminator;
4367 uint _n_workers;
4368
4369 public:
4370 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4371 AbstractGangTask("ParPreserveCMReferents"),
4372 _g1h(g1h),
4373 _pss(per_thread_states),
4374 _queues(task_queues),
4375 _terminator(workers, _queues),
4376 _n_workers(workers)
4377 {
4378 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4379 }
4380
4381 void work(uint worker_id) {
4382 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4383
4384 ResourceMark rm;
4385 HandleMark hm;
4386
4387 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4388 pss->set_ref_processor(NULL);
4389 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4390
4391 // Is alive closure
4392 G1AlwaysAliveClosure always_alive(_g1h);
4393
4394 // Copying keep alive closure. Applied to referent objects that need
4395 // to be copied.
4396 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4397
4398 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4399
4400 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4401 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4402
4403 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4404 // So this must be true - but assert just in case someone decides to
4405 // change the worker ids.
4406 assert(worker_id < limit, "sanity");
4407 assert(!rp->discovery_is_atomic(), "check this code");
4408
4409 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4410 for (uint idx = worker_id; idx < limit; idx += stride) {
4411 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4412
4413 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4414 while (iter.has_next()) {
4415 // Since discovery is not atomic for the CM ref processor, we
4416 // can see some null referent objects.
4417 iter.load_ptrs(DEBUG_ONLY(true));
4418 oop ref = iter.obj();
4419
4420 // This will filter nulls.
4421 if (iter.is_referent_alive()) {
4422 iter.make_referent_alive();
4423 }
4424 iter.move_to_next();
4425 }
4426 }
4427
4428 // Drain the queue - which may cause stealing
4429 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4430 drain_queue.do_void();
4431 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4432 assert(pss->queue_is_empty(), "should be");
4433 }
4434 };
4435
4436 void G1CollectedHeap::process_weak_jni_handles() {
4437 double ref_proc_start = os::elapsedTime();
4438
4439 G1STWIsAliveClosure is_alive(this);
4440 G1KeepAliveClosure keep_alive(this);
4441 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4442
4443 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4444 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4445 }
4446
4447 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4448 double preserve_cm_referents_start = os::elapsedTime();
4449 // Any reference objects, in the collection set, that were 'discovered'
4450 // by the CM ref processor should have already been copied (either by
4451 // applying the external root copy closure to the discovered lists, or
4452 // by following an RSet entry).
4453 //
4454 // But some of the referents, that are in the collection set, that these
4455 // reference objects point to may not have been copied: the STW ref
4456 // processor would have seen that the reference object had already
4457 // been 'discovered' and would have skipped discovering the reference,
4458 // but would not have treated the reference object as a regular oop.
4459 // As a result the copy closure would not have been applied to the
4460 // referent object.
4461 //
4462 // We need to explicitly copy these referent objects - the references
4463 // will be processed at the end of remarking.
4464 //
4465 // We also need to do this copying before we process the reference
4466 // objects discovered by the STW ref processor in case one of these
4467 // referents points to another object which is also referenced by an
4468 // object discovered by the STW ref processor.
4469
4470 uint no_of_gc_workers = workers()->active_workers();
4471
4472 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4473 per_thread_states,
4474 no_of_gc_workers,
4475 _task_queues);
4476 workers()->run_task(&keep_cm_referents);
4477
4478 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4479 }
4480
4481 // Weak Reference processing during an evacuation pause (part 1).
4482 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4483 double ref_proc_start = os::elapsedTime();
4484
4485 ReferenceProcessor* rp = _ref_processor_stw;
4486 assert(rp->discovery_enabled(), "should have been enabled");
4487
4488 // Closure to test whether a referent is alive.
4489 G1STWIsAliveClosure is_alive(this);
4490
4491 // Even when parallel reference processing is enabled, the processing
4492 // of JNI refs is serial and performed serially by the current thread
4493 // rather than by a worker. The following PSS will be used for processing
4494 // JNI refs.
4495
4496 // Use only a single queue for this PSS.
4497 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4498 pss->set_ref_processor(NULL);
4499 assert(pss->queue_is_empty(), "pre-condition");
4500
4501 // Keep alive closure.
4502 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4503
4504 // Serial Complete GC closure
4505 G1STWDrainQueueClosure drain_queue(this, pss);
4506
4507 // Setup the soft refs policy...
4508 rp->setup_policy(false);
4509
4510 ReferenceProcessorStats stats;
4511 if (!rp->processing_is_mt()) {
4512 // Serial reference processing...
4513 stats = rp->process_discovered_references(&is_alive,
4514 &keep_alive,
4515 &drain_queue,
4516 NULL,
4517 _gc_timer_stw);
4518 } else {
4519 uint no_of_gc_workers = workers()->active_workers();
4520
4521 // Parallel reference processing
4522 assert(no_of_gc_workers <= rp->max_num_q(),
4523 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4524 no_of_gc_workers, rp->max_num_q());
4525
4526 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4527 stats = rp->process_discovered_references(&is_alive,
4528 &keep_alive,
4529 &drain_queue,
4530 &par_task_executor,
4531 _gc_timer_stw);
4532 }
4533
4534 _gc_tracer_stw->report_gc_reference_stats(stats);
4535
4536 // We have completed copying any necessary live referent objects.
4537 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4538
4539 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4540 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4541 }
4542
4543 // Weak Reference processing during an evacuation pause (part 2).
4544 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4545 double ref_enq_start = os::elapsedTime();
4546
4547 ReferenceProcessor* rp = _ref_processor_stw;
4548 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4549
4550 // Now enqueue any remaining on the discovered lists on to
4551 // the pending list.
4552 if (!rp->processing_is_mt()) {
4553 // Serial reference processing...
4554 rp->enqueue_discovered_references();
4555 } else {
4556 // Parallel reference enqueueing
4557
4558 uint n_workers = workers()->active_workers();
4559
4560 assert(n_workers <= rp->max_num_q(),
4561 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4562 n_workers, rp->max_num_q());
4563
4564 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4565 rp->enqueue_discovered_references(&par_task_executor);
4566 }
4567
4568 rp->verify_no_references_recorded();
4569 assert(!rp->discovery_enabled(), "should have been disabled");
4570
4571 // FIXME
4572 // CM's reference processing also cleans up the string and symbol tables.
4573 // Should we do that here also? We could, but it is a serial operation
4574 // and could significantly increase the pause time.
4575
4576 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4577 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4578 }
4579
4580 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4581 double merge_pss_time_start = os::elapsedTime();
4582 per_thread_states->flush();
4583 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4584 }
4585
4586 void G1CollectedHeap::pre_evacuate_collection_set() {
4587 _expand_heap_after_alloc_failure = true;
4588 _evacuation_failed = false;
4589
4590 // Disable the hot card cache.
4591 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4592 hot_card_cache->reset_hot_cache_claimed_index();
4593 hot_card_cache->set_use_cache(false);
4594
4595 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4596 }
4597
4598 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4599 // Should G1EvacuationFailureALot be in effect for this GC?
4600 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4601
4602 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4603 double start_par_time_sec = os::elapsedTime();
4604 double end_par_time_sec;
4605
4606 {
4607 const uint n_workers = workers()->active_workers();
4608 G1RootProcessor root_processor(this, n_workers);
4609 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4610 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4611 if (collector_state()->during_initial_mark_pause()) {
4612 ClassLoaderDataGraph::clear_claimed_marks();
4613 }
4614
4615 print_termination_stats_hdr();
4616
4617 workers()->run_task(&g1_par_task);
4618 end_par_time_sec = os::elapsedTime();
4619
4620 // Closing the inner scope will execute the destructor
4621 // for the G1RootProcessor object. We record the current
4622 // elapsed time before closing the scope so that time
4623 // taken for the destructor is NOT included in the
4624 // reported parallel time.
4625 }
4626
4627 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4628
4629 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4630 phase_times->record_par_time(par_time_ms);
4631
4632 double code_root_fixup_time_ms =
4633 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4634 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4635 }
4636
4637 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4638 // Process any discovered reference objects - we have
4639 // to do this _before_ we retire the GC alloc regions
4640 // as we may have to copy some 'reachable' referent
4641 // objects (and their reachable sub-graphs) that were
4642 // not copied during the pause.
4643 if (g1_policy()->should_process_references()) {
4644 preserve_cm_referents(per_thread_states);
4645 process_discovered_references(per_thread_states);
4646 } else {
4647 ref_processor_stw()->verify_no_references_recorded();
4648 process_weak_jni_handles();
4649 }
4650
4651 if (G1StringDedup::is_enabled()) {
4652 double fixup_start = os::elapsedTime();
4653
4654 G1STWIsAliveClosure is_alive(this);
4655 G1KeepAliveClosure keep_alive(this);
4656 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4657
4658 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4659 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4660 }
4661
4662 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4663
4664 if (evacuation_failed()) {
4665 restore_after_evac_failure();
4666
4667 // Reset the G1EvacuationFailureALot counters and flags
4668 // Note: the values are reset only when an actual
4669 // evacuation failure occurs.
4670 NOT_PRODUCT(reset_evacuation_should_fail();)
4671 }
4672
4673 // Enqueue any remaining references remaining on the STW
4674 // reference processor's discovered lists. We need to do
4675 // this after the card table is cleaned (and verified) as
4676 // the act of enqueueing entries on to the pending list
4677 // will log these updates (and dirty their associated
4678 // cards). We need these updates logged to update any
4679 // RSets.
4680 if (g1_policy()->should_process_references()) {
4681 enqueue_discovered_references(per_thread_states);
4682 } else {
4683 g1_policy()->phase_times()->record_ref_enq_time(0);
4684 }
4685
4686 _allocator->release_gc_alloc_regions(evacuation_info);
4687
4688 merge_per_thread_state_info(per_thread_states);
4689
4690 // Reset and re-enable the hot card cache.
4691 // Note the counts for the cards in the regions in the
4692 // collection set are reset when the collection set is freed.
4693 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4694 hot_card_cache->reset_hot_cache();
4695 hot_card_cache->set_use_cache(true);
4696
4697 purge_code_root_memory();
4698
4699 redirty_logged_cards();
4700 #if defined(COMPILER2) || INCLUDE_JVMCI
4701 DerivedPointerTable::update_pointers();
4702 #endif
4703 }
4704
4705 void G1CollectedHeap::record_obj_copy_mem_stats() {
4706 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4707
4708 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4709 create_g1_evac_summary(&_old_evac_stats));
4710 }
4711
4712 void G1CollectedHeap::free_region(HeapRegion* hr,
4713 FreeRegionList* free_list,
4714 bool par,
4715 bool locked) {
4716 assert(!hr->is_free(), "the region should not be free");
4717 assert(!hr->is_empty(), "the region should not be empty");
4718 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4719 assert(free_list != NULL, "pre-condition");
4720
4721 if (G1VerifyBitmaps) {
4722 MemRegion mr(hr->bottom(), hr->end());
4723 concurrent_mark()->clearRangePrevBitmap(mr);
4724 }
4725
4726 // Clear the card counts for this region.
4727 // Note: we only need to do this if the region is not young
4728 // (since we don't refine cards in young regions).
4729 if (!hr->is_young()) {
4730 _cg1r->hot_card_cache()->reset_card_counts(hr);
4731 }
4732 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4733 free_list->add_ordered(hr);
4734 }
4735
4736 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4737 FreeRegionList* free_list,
4738 bool par) {
4739 assert(hr->is_humongous(), "this is only for humongous regions");
4740 assert(free_list != NULL, "pre-condition");
4741 hr->clear_humongous();
4742 free_region(hr, free_list, par);
4743 }
4744
4745 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4746 const uint humongous_regions_removed) {
4747 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4748 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4749 _old_set.bulk_remove(old_regions_removed);
4750 _humongous_set.bulk_remove(humongous_regions_removed);
4751 }
4752
4753 }
4754
4755 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4756 assert(list != NULL, "list can't be null");
4757 if (!list->is_empty()) {
4758 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4759 _hrm.insert_list_into_free_list(list);
4760 }
4761 }
4762
4763 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4764 decrease_used(bytes);
4765 }
4766
4767 class G1ParCleanupCTTask : public AbstractGangTask {
4768 G1SATBCardTableModRefBS* _ct_bs;
4769 G1CollectedHeap* _g1h;
4770 HeapRegion* volatile _su_head;
4771 public:
4772 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4773 G1CollectedHeap* g1h) :
4774 AbstractGangTask("G1 Par Cleanup CT Task"),
4775 _ct_bs(ct_bs), _g1h(g1h) { }
4776
4777 void work(uint worker_id) {
4778 HeapRegion* r;
4779 while (r = _g1h->pop_dirty_cards_region()) {
4780 clear_cards(r);
4781 }
4782 }
4783
4784 void clear_cards(HeapRegion* r) {
4785 // Cards of the survivors should have already been dirtied.
4786 if (!r->is_survivor()) {
4787 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4788 }
4789 }
4790 };
4791
4792 class G1ParScrubRemSetTask: public AbstractGangTask {
4793 protected:
4794 G1RemSet* _g1rs;
4795 HeapRegionClaimer _hrclaimer;
4796
4797 public:
4798 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4799 AbstractGangTask("G1 ScrubRS"),
4800 _g1rs(g1_rs),
4801 _hrclaimer(num_workers) {
4802 }
4803
4804 void work(uint worker_id) {
4805 _g1rs->scrub(worker_id, &_hrclaimer);
4806 }
4807 };
4808
4809 void G1CollectedHeap::scrub_rem_set() {
4810 uint num_workers = workers()->active_workers();
4811 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4812 workers()->run_task(&g1_par_scrub_rs_task);
4813 }
4814
4815 void G1CollectedHeap::cleanUpCardTable() {
4816 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4817 double start = os::elapsedTime();
4818
4819 {
4820 // Iterate over the dirty cards region list.
4821 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4822
4823 workers()->run_task(&cleanup_task);
4824 #ifndef PRODUCT
4825 _verifier->verify_card_table_cleanup();
4826 #endif
4827 }
4828
4829 double elapsed = os::elapsedTime() - start;
4830 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4831 }
4832
4833 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4834 size_t pre_used = 0;
4835 FreeRegionList local_free_list("Local List for CSet Freeing");
4836
4837 double young_time_ms = 0.0;
4838 double non_young_time_ms = 0.0;
4839
4840 // Since the collection set is a superset of the the young list,
4841 // all we need to do to clear the young list is clear its
4842 // head and length, and unlink any young regions in the code below
4843 _young_list->clear();
4844
4845 G1CollectorPolicy* policy = g1_policy();
4846
4847 double start_sec = os::elapsedTime();
4848 bool non_young = true;
4849
4850 HeapRegion* cur = cs_head;
4851 int age_bound = -1;
4852 size_t rs_lengths = 0;
4853
4854 while (cur != NULL) {
4855 assert(!is_on_master_free_list(cur), "sanity");
4856 if (non_young) {
4857 if (cur->is_young()) {
4858 double end_sec = os::elapsedTime();
4859 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4860 non_young_time_ms += elapsed_ms;
4861
4862 start_sec = os::elapsedTime();
4863 non_young = false;
4864 }
4865 } else {
4866 if (!cur->is_young()) {
4867 double end_sec = os::elapsedTime();
4868 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4869 young_time_ms += elapsed_ms;
4870
4871 start_sec = os::elapsedTime();
4872 non_young = true;
4873 }
4874 }
4875
4876 rs_lengths += cur->rem_set()->occupied_locked();
4877
4878 HeapRegion* next = cur->next_in_collection_set();
4879 assert(cur->in_collection_set(), "bad CS");
4880 cur->set_next_in_collection_set(NULL);
4881 clear_in_cset(cur);
4882
4883 if (cur->is_young()) {
4884 int index = cur->young_index_in_cset();
4885 assert(index != -1, "invariant");
4886 assert((uint) index < collection_set()->young_region_length(), "invariant");
4887 size_t words_survived = surviving_young_words[index];
4888 cur->record_surv_words_in_group(words_survived);
4889
4890 // At this point the we have 'popped' cur from the collection set
4891 // (linked via next_in_collection_set()) but it is still in the
4892 // young list (linked via next_young_region()). Clear the
4893 // _next_young_region field.
4894 cur->set_next_young_region(NULL);
4895 } else {
4896 int index = cur->young_index_in_cset();
4897 assert(index == -1, "invariant");
4898 }
4899
4900 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4901 (!cur->is_young() && cur->young_index_in_cset() == -1),
4902 "invariant" );
4903
4904 if (!cur->evacuation_failed()) {
4905 MemRegion used_mr = cur->used_region();
4906
4907 // And the region is empty.
4908 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4909 pre_used += cur->used();
4910 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4911 } else {
4912 cur->uninstall_surv_rate_group();
4913 if (cur->is_young()) {
4914 cur->set_young_index_in_cset(-1);
4915 }
4916 cur->set_evacuation_failed(false);
4917 // When moving a young gen region to old gen, we "allocate" that whole region
4918 // there. This is in addition to any already evacuated objects. Notify the
4919 // policy about that.
4920 // Old gen regions do not cause an additional allocation: both the objects
4921 // still in the region and the ones already moved are accounted for elsewhere.
4922 if (cur->is_young()) {
4923 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4924 }
4925 // The region is now considered to be old.
4926 cur->set_old();
4927 // Do some allocation statistics accounting. Regions that failed evacuation
4928 // are always made old, so there is no need to update anything in the young
4929 // gen statistics, but we need to update old gen statistics.
4930 size_t used_words = cur->marked_bytes() / HeapWordSize;
4931 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4932 _old_set.add(cur);
4933 evacuation_info.increment_collectionset_used_after(cur->used());
4934 }
4935 cur = next;
4936 }
4937
4938 evacuation_info.set_regions_freed(local_free_list.length());
4939 policy->record_max_rs_lengths(rs_lengths);
4940 policy->cset_regions_freed();
4941
4942 double end_sec = os::elapsedTime();
4943 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4944
4945 if (non_young) {
4946 non_young_time_ms += elapsed_ms;
4947 } else {
4948 young_time_ms += elapsed_ms;
4949 }
4950
4951 prepend_to_freelist(&local_free_list);
4952 decrement_summary_bytes(pre_used);
4953 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4954 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4955 }
4956
4957 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4958 private:
4959 FreeRegionList* _free_region_list;
4960 HeapRegionSet* _proxy_set;
4961 uint _humongous_regions_removed;
4962 size_t _freed_bytes;
4963 public:
4964
4965 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4966 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4967 }
4968
4969 virtual bool doHeapRegion(HeapRegion* r) {
4970 if (!r->is_starts_humongous()) {
4971 return false;
4972 }
4973
4974 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4975
4976 oop obj = (oop)r->bottom();
4977 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4978
4979 // The following checks whether the humongous object is live are sufficient.
4980 // The main additional check (in addition to having a reference from the roots
4981 // or the young gen) is whether the humongous object has a remembered set entry.
4982 //
4983 // A humongous object cannot be live if there is no remembered set for it
4984 // because:
4985 // - there can be no references from within humongous starts regions referencing
4986 // the object because we never allocate other objects into them.
4987 // (I.e. there are no intra-region references that may be missed by the
4988 // remembered set)
4989 // - as soon there is a remembered set entry to the humongous starts region
4990 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4991 // until the end of a concurrent mark.
4992 //
4993 // It is not required to check whether the object has been found dead by marking
4994 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4995 // all objects allocated during that time are considered live.
4996 // SATB marking is even more conservative than the remembered set.
4997 // So if at this point in the collection there is no remembered set entry,
4998 // nobody has a reference to it.
4999 // At the start of collection we flush all refinement logs, and remembered sets
5000 // are completely up-to-date wrt to references to the humongous object.
5001 //
5002 // Other implementation considerations:
5003 // - never consider object arrays at this time because they would pose
5004 // considerable effort for cleaning up the the remembered sets. This is
5005 // required because stale remembered sets might reference locations that
5006 // are currently allocated into.
5007 uint region_idx = r->hrm_index();
5008 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5009 !r->rem_set()->is_empty()) {
5010 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5011 region_idx,
5012 (size_t)obj->size() * HeapWordSize,
5013 p2i(r->bottom()),
5014 r->rem_set()->occupied(),
5015 r->rem_set()->strong_code_roots_list_length(),
5016 next_bitmap->isMarked(r->bottom()),
5017 g1h->is_humongous_reclaim_candidate(region_idx),
5018 obj->is_typeArray()
5019 );
5020 return false;
5021 }
5022
5023 guarantee(obj->is_typeArray(),
5024 "Only eagerly reclaiming type arrays is supported, but the object "
5025 PTR_FORMAT " is not.", p2i(r->bottom()));
5026
5027 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5028 region_idx,
5029 (size_t)obj->size() * HeapWordSize,
5030 p2i(r->bottom()),
5031 r->rem_set()->occupied(),
5032 r->rem_set()->strong_code_roots_list_length(),
5033 next_bitmap->isMarked(r->bottom()),
5034 g1h->is_humongous_reclaim_candidate(region_idx),
5035 obj->is_typeArray()
5036 );
5037
5038 // Need to clear mark bit of the humongous object if already set.
5039 if (next_bitmap->isMarked(r->bottom())) {
5040 next_bitmap->clear(r->bottom());
5041 }
5042 do {
5043 HeapRegion* next = g1h->next_region_in_humongous(r);
5044 _freed_bytes += r->used();
5045 r->set_containing_set(NULL);
5046 _humongous_regions_removed++;
5047 g1h->free_humongous_region(r, _free_region_list, false);
5048 r = next;
5049 } while (r != NULL);
5050
5051 return false;
5052 }
5053
5054 uint humongous_free_count() {
5055 return _humongous_regions_removed;
5056 }
5057
5058 size_t bytes_freed() const {
5059 return _freed_bytes;
5060 }
5061 };
5062
5063 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5064 assert_at_safepoint(true);
5065
5066 if (!G1EagerReclaimHumongousObjects ||
5067 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5068 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5069 return;
5070 }
5071
5072 double start_time = os::elapsedTime();
5073
5074 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5075
5076 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5077 heap_region_iterate(&cl);
5078
5079 remove_from_old_sets(0, cl.humongous_free_count());
5080
5081 G1HRPrinter* hrp = hr_printer();
5082 if (hrp->is_active()) {
5083 FreeRegionListIterator iter(&local_cleanup_list);
5084 while (iter.more_available()) {
5085 HeapRegion* hr = iter.get_next();
5086 hrp->cleanup(hr);
5087 }
5088 }
5089
5090 prepend_to_freelist(&local_cleanup_list);
5091 decrement_summary_bytes(cl.bytes_freed());
5092
5093 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5094 cl.humongous_free_count());
5095 }
5096
5097 // This routine is similar to the above but does not record
5098 // any policy statistics or update free lists; we are abandoning
5099 // the current incremental collection set in preparation of a
5100 // full collection. After the full GC we will start to build up
5101 // the incremental collection set again.
5102 // This is only called when we're doing a full collection
5103 // and is immediately followed by the tearing down of the young list.
5104
5105 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5106 HeapRegion* cur = cs_head;
5107
5108 while (cur != NULL) {
5109 HeapRegion* next = cur->next_in_collection_set();
5110 assert(cur->in_collection_set(), "bad CS");
5111 cur->set_next_in_collection_set(NULL);
5112 clear_in_cset(cur);
5113 cur->set_young_index_in_cset(-1);
5114 cur = next;
5115 }
5116 }
5117
5118 void G1CollectedHeap::set_free_regions_coming() {
5119 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5120
5121 assert(!free_regions_coming(), "pre-condition");
5122 _free_regions_coming = true;
5123 }
5124
5125 void G1CollectedHeap::reset_free_regions_coming() {
5126 assert(free_regions_coming(), "pre-condition");
5127
5128 {
5129 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5130 _free_regions_coming = false;
5131 SecondaryFreeList_lock->notify_all();
5132 }
5133
5134 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5135 }
5136
5137 void G1CollectedHeap::wait_while_free_regions_coming() {
5138 // Most of the time we won't have to wait, so let's do a quick test
5139 // first before we take the lock.
5140 if (!free_regions_coming()) {
5141 return;
5142 }
5143
5144 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5145
5146 {
5147 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5148 while (free_regions_coming()) {
5149 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5150 }
5151 }
5152
5153 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5154 }
5155
5156 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5157 return _allocator->is_retained_old_region(hr);
5158 }
5159
5160 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5161 _young_list->push_region(hr);
5162 }
5163
5164 class NoYoungRegionsClosure: public HeapRegionClosure {
5165 private:
5166 bool _success;
5167 public:
5168 NoYoungRegionsClosure() : _success(true) { }
5169 bool doHeapRegion(HeapRegion* r) {
5170 if (r->is_young()) {
5171 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5172 p2i(r->bottom()), p2i(r->end()));
5173 _success = false;
5174 }
5175 return false;
5176 }
5177 bool success() { return _success; }
5178 };
5179
5180 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5181 bool ret = _young_list->check_list_empty();
5182
5183 if (check_heap) {
5184 NoYoungRegionsClosure closure;
5185 heap_region_iterate(&closure);
5186 ret = ret && closure.success();
5187 }
5188
5189 return ret;
5190 }
5191
5192 class TearDownRegionSetsClosure : public HeapRegionClosure {
5193 private:
5194 HeapRegionSet *_old_set;
5195
5196 public:
5197 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5198
5199 bool doHeapRegion(HeapRegion* r) {
5200 if (r->is_old()) {
5201 _old_set->remove(r);
5202 } else {
5203 // We ignore free regions, we'll empty the free list afterwards.
5204 // We ignore young regions, we'll empty the young list afterwards.
5205 // We ignore humongous regions, we're not tearing down the
5206 // humongous regions set.
5207 assert(r->is_free() || r->is_young() || r->is_humongous(),
5208 "it cannot be another type");
5209 }
5210 return false;
5211 }
5212
5213 ~TearDownRegionSetsClosure() {
5214 assert(_old_set->is_empty(), "post-condition");
5215 }
5216 };
5217
5218 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5219 assert_at_safepoint(true /* should_be_vm_thread */);
5220
5221 if (!free_list_only) {
5222 TearDownRegionSetsClosure cl(&_old_set);
5223 heap_region_iterate(&cl);
5224
5225 // Note that emptying the _young_list is postponed and instead done as
5226 // the first step when rebuilding the regions sets again. The reason for
5227 // this is that during a full GC string deduplication needs to know if
5228 // a collected region was young or old when the full GC was initiated.
5229 }
5230 _hrm.remove_all_free_regions();
5231 }
5232
5233 void G1CollectedHeap::increase_used(size_t bytes) {
5234 _summary_bytes_used += bytes;
5235 }
5236
5237 void G1CollectedHeap::decrease_used(size_t bytes) {
5238 assert(_summary_bytes_used >= bytes,
5239 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5240 _summary_bytes_used, bytes);
5241 _summary_bytes_used -= bytes;
5242 }
5243
5244 void G1CollectedHeap::set_used(size_t bytes) {
5245 _summary_bytes_used = bytes;
5246 }
5247
5248 class RebuildRegionSetsClosure : public HeapRegionClosure {
5249 private:
5250 bool _free_list_only;
5251 HeapRegionSet* _old_set;
5252 HeapRegionManager* _hrm;
5253 size_t _total_used;
5254
5255 public:
5256 RebuildRegionSetsClosure(bool free_list_only,
5257 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5258 _free_list_only(free_list_only),
5259 _old_set(old_set), _hrm(hrm), _total_used(0) {
5260 assert(_hrm->num_free_regions() == 0, "pre-condition");
5261 if (!free_list_only) {
5262 assert(_old_set->is_empty(), "pre-condition");
5263 }
5264 }
5265
5266 bool doHeapRegion(HeapRegion* r) {
5267 if (r->is_empty()) {
5268 // Add free regions to the free list
5269 r->set_free();
5270 r->set_allocation_context(AllocationContext::system());
5271 _hrm->insert_into_free_list(r);
5272 } else if (!_free_list_only) {
5273 assert(!r->is_young(), "we should not come across young regions");
5274
5275 if (r->is_humongous()) {
5276 // We ignore humongous regions. We left the humongous set unchanged.
5277 } else {
5278 // Objects that were compacted would have ended up on regions
5279 // that were previously old or free. Archive regions (which are
5280 // old) will not have been touched.
5281 assert(r->is_free() || r->is_old(), "invariant");
5282 // We now consider them old, so register as such. Leave
5283 // archive regions set that way, however, while still adding
5284 // them to the old set.
5285 if (!r->is_archive()) {
5286 r->set_old();
5287 }
5288 _old_set->add(r);
5289 }
5290 _total_used += r->used();
5291 }
5292
5293 return false;
5294 }
5295
5296 size_t total_used() {
5297 return _total_used;
5298 }
5299 };
5300
5301 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5302 assert_at_safepoint(true /* should_be_vm_thread */);
5303
5304 if (!free_list_only) {
5305 _young_list->empty_list();
5306 }
5307
5308 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5309 heap_region_iterate(&cl);
5310
5311 if (!free_list_only) {
5312 set_used(cl.total_used());
5313 if (_archive_allocator != NULL) {
5314 _archive_allocator->clear_used();
5315 }
5316 }
5317 assert(used_unlocked() == recalculate_used(),
5318 "inconsistent used_unlocked(), "
5319 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5320 used_unlocked(), recalculate_used());
5321 }
5322
5323 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5324 _refine_cte_cl->set_concurrent(concurrent);
5325 }
5326
5327 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5328 HeapRegion* hr = heap_region_containing(p);
5329 return hr->is_in(p);
5330 }
5331
5332 // Methods for the mutator alloc region
5333
5334 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5335 bool force) {
5336 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5337 assert(!force || g1_policy()->can_expand_young_list(),
5338 "if force is true we should be able to expand the young list");
5339 bool young_list_full = g1_policy()->is_young_list_full();
5340 if (force || !young_list_full) {
5341 HeapRegion* new_alloc_region = new_region(word_size,
5342 false /* is_old */,
5343 false /* do_expand */);
5344 if (new_alloc_region != NULL) {
5345 set_region_short_lived_locked(new_alloc_region);
5346 _hr_printer.alloc(new_alloc_region, young_list_full);
5347 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5348 return new_alloc_region;
5349 }
5350 }
5351 return NULL;
5352 }
5353
5354 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5355 size_t allocated_bytes) {
5356 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5357 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5358
5359 collection_set()->add_eden_region(alloc_region);
5360 increase_used(allocated_bytes);
5361 _hr_printer.retire(alloc_region);
5362 // We update the eden sizes here, when the region is retired,
5363 // instead of when it's allocated, since this is the point that its
5364 // used space has been recored in _summary_bytes_used.
5365 g1mm()->update_eden_size();
5366 }
5367
5368 // Methods for the GC alloc regions
5369
5370 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5371 if (dest.is_old()) {
5372 return true;
5373 } else {
5374 return young_list()->survivor_length() < g1_policy()->max_survivor_regions();
5375 }
5376 }
5377
5378 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5379 assert(FreeList_lock->owned_by_self(), "pre-condition");
5380
5381 if (!has_more_regions(dest)) {
5382 return NULL;
5383 }
5384
5385 const bool is_survivor = dest.is_young();
5386
5387 HeapRegion* new_alloc_region = new_region(word_size,
5388 !is_survivor,
5389 true /* do_expand */);
5390 if (new_alloc_region != NULL) {
5391 // We really only need to do this for old regions given that we
5392 // should never scan survivors. But it doesn't hurt to do it
5393 // for survivors too.
5394 new_alloc_region->record_timestamp();
5395 if (is_survivor) {
5396 new_alloc_region->set_survivor();
5397 young_list()->add_survivor_region(new_alloc_region);
5398 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5399 } else {
5400 new_alloc_region->set_old();
5401 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5402 }
5403 _hr_printer.alloc(new_alloc_region);
5404 bool during_im = collector_state()->during_initial_mark_pause();
5405 new_alloc_region->note_start_of_copying(during_im);
5406 return new_alloc_region;
5407 }
5408 return NULL;
5409 }
5410
5411 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5412 size_t allocated_bytes,
5413 InCSetState dest) {
5414 bool during_im = collector_state()->during_initial_mark_pause();
5415 alloc_region->note_end_of_copying(during_im);
5416 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5417 if (dest.is_old()) {
5418 _old_set.add(alloc_region);
5419 }
5420 _hr_printer.retire(alloc_region);
5421 }
5422
5423 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5424 bool expanded = false;
5425 uint index = _hrm.find_highest_free(&expanded);
5426
5427 if (index != G1_NO_HRM_INDEX) {
5428 if (expanded) {
5429 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5430 HeapRegion::GrainWords * HeapWordSize);
5431 }
5432 _hrm.allocate_free_regions_starting_at(index, 1);
5433 return region_at(index);
5434 }
5435 return NULL;
5436 }
5437
5438 // Optimized nmethod scanning
5439
5440 class RegisterNMethodOopClosure: public OopClosure {
5441 G1CollectedHeap* _g1h;
5442 nmethod* _nm;
5443
5444 template <class T> void do_oop_work(T* p) {
5445 T heap_oop = oopDesc::load_heap_oop(p);
5446 if (!oopDesc::is_null(heap_oop)) {
5447 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5448 HeapRegion* hr = _g1h->heap_region_containing(obj);
5449 assert(!hr->is_continues_humongous(),
5450 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5451 " starting at " HR_FORMAT,
5452 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5453
5454 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5455 hr->add_strong_code_root_locked(_nm);
5456 }
5457 }
5458
5459 public:
5460 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5461 _g1h(g1h), _nm(nm) {}
5462
5463 void do_oop(oop* p) { do_oop_work(p); }
5464 void do_oop(narrowOop* p) { do_oop_work(p); }
5465 };
5466
5467 class UnregisterNMethodOopClosure: public OopClosure {
5468 G1CollectedHeap* _g1h;
5469 nmethod* _nm;
5470
5471 template <class T> void do_oop_work(T* p) {
5472 T heap_oop = oopDesc::load_heap_oop(p);
5473 if (!oopDesc::is_null(heap_oop)) {
5474 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5475 HeapRegion* hr = _g1h->heap_region_containing(obj);
5476 assert(!hr->is_continues_humongous(),
5477 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5478 " starting at " HR_FORMAT,
5479 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5480
5481 hr->remove_strong_code_root(_nm);
5482 }
5483 }
5484
5485 public:
5486 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5487 _g1h(g1h), _nm(nm) {}
5488
5489 void do_oop(oop* p) { do_oop_work(p); }
5490 void do_oop(narrowOop* p) { do_oop_work(p); }
5491 };
5492
5493 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5494 CollectedHeap::register_nmethod(nm);
5495
5496 guarantee(nm != NULL, "sanity");
5497 RegisterNMethodOopClosure reg_cl(this, nm);
5498 nm->oops_do(®_cl);
5499 }
5500
5501 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5502 CollectedHeap::unregister_nmethod(nm);
5503
5504 guarantee(nm != NULL, "sanity");
5505 UnregisterNMethodOopClosure reg_cl(this, nm);
5506 nm->oops_do(®_cl, true);
5507 }
5508
5509 void G1CollectedHeap::purge_code_root_memory() {
5510 double purge_start = os::elapsedTime();
5511 G1CodeRootSet::purge();
5512 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5513 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5514 }
5515
5516 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5517 G1CollectedHeap* _g1h;
5518
5519 public:
5520 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5521 _g1h(g1h) {}
5522
5523 void do_code_blob(CodeBlob* cb) {
5524 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5525 if (nm == NULL) {
5526 return;
5527 }
5528
5529 if (ScavengeRootsInCode) {
5530 _g1h->register_nmethod(nm);
5531 }
5532 }
5533 };
5534
5535 void G1CollectedHeap::rebuild_strong_code_roots() {
5536 RebuildStrongCodeRootClosure blob_cl(this);
5537 CodeCache::blobs_do(&blob_cl);
5538 }