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/g1HeapTransition.hpp"
43 #include "gc/g1/g1HeapVerifier.hpp"
44 #include "gc/g1/g1MarkSweep.hpp"
45 #include "gc/g1/g1OopClosures.inline.hpp"
46 #include "gc/g1/g1ParScanThreadState.inline.hpp"
47 #include "gc/g1/g1RegionToSpaceMapper.hpp"
48 #include "gc/g1/g1RemSet.inline.hpp"
49 #include "gc/g1/g1RootClosures.hpp"
50 #include "gc/g1/g1RootProcessor.hpp"
51 #include "gc/g1/g1StringDedup.hpp"
52 #include "gc/g1/g1YCTypes.hpp"
53 #include "gc/g1/heapRegion.inline.hpp"
54 #include "gc/g1/heapRegionRemSet.hpp"
55 #include "gc/g1/heapRegionSet.inline.hpp"
56 #include "gc/g1/suspendibleThreadSet.hpp"
57 #include "gc/g1/vm_operations_g1.hpp"
58 #include "gc/shared/gcHeapSummary.hpp"
59 #include "gc/shared/gcId.hpp"
60 #include "gc/shared/gcLocker.inline.hpp"
61 #include "gc/shared/gcTimer.hpp"
62 #include "gc/shared/gcTrace.hpp"
63 #include "gc/shared/gcTraceTime.inline.hpp"
64 #include "gc/shared/generationSpec.hpp"
65 #include "gc/shared/isGCActiveMark.hpp"
66 #include "gc/shared/referenceProcessor.inline.hpp"
67 #include "gc/shared/taskqueue.inline.hpp"
68 #include "logging/log.hpp"
69 #include "memory/allocation.hpp"
70 #include "memory/iterator.hpp"
71 #include "oops/oop.inline.hpp"
72 #include "runtime/atomic.inline.hpp"
73 #include "runtime/init.hpp"
74 #include "runtime/orderAccess.inline.hpp"
75 #include "runtime/vmThread.hpp"
76 #include "utilities/globalDefinitions.hpp"
77 #include "utilities/stack.inline.hpp"
78
79 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
80
81 // INVARIANTS/NOTES
82 //
83 // All allocation activity covered by the G1CollectedHeap interface is
84 // serialized by acquiring the HeapLock. This happens in mem_allocate
85 // and allocate_new_tlab, which are the "entry" points to the
86 // allocation code from the rest of the JVM. (Note that this does not
87 // apply to TLAB allocation, which is not part of this interface: it
88 // is done by clients of this interface.)
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 bool _concurrent;
94 public:
95 RefineCardTableEntryClosure() : _concurrent(true) { }
96
97 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
98 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
99 // This path is executed by the concurrent refine or mutator threads,
100 // concurrently, and so we do not care if card_ptr contains references
101 // that point into the collection set.
102 assert(!oops_into_cset, "should be");
103
104 if (_concurrent && SuspendibleThreadSet::should_yield()) {
105 // Caller will actually yield.
106 return false;
107 }
108 // Otherwise, we finished successfully; return true.
109 return true;
110 }
111
112 void set_concurrent(bool b) { _concurrent = b; }
113 };
114
115
116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
117 private:
118 size_t _num_dirtied;
119 G1CollectedHeap* _g1h;
120 G1SATBCardTableLoggingModRefBS* _g1_bs;
121
122 HeapRegion* region_for_card(jbyte* card_ptr) const {
123 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
124 }
125
126 bool will_become_free(HeapRegion* hr) const {
127 // A region will be freed by free_collection_set if the region is in the
128 // collection set and has not had an evacuation failure.
129 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
130 }
131
132 public:
133 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
134 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
135
136 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
137 HeapRegion* hr = region_for_card(card_ptr);
138
139 // Should only dirty cards in regions that won't be freed.
140 if (!will_become_free(hr)) {
141 *card_ptr = CardTableModRefBS::dirty_card_val();
142 _num_dirtied++;
143 }
144
145 return true;
146 }
147
148 size_t num_dirtied() const { return _num_dirtied; }
149 };
150
151
152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
154 }
155
156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
157 // The from card cache is not the memory that is actually committed. So we cannot
158 // take advantage of the zero_filled parameter.
159 reset_from_card_cache(start_idx, num_regions);
160 }
161
162 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
163 {
164 // Claim the right to put the region on the dirty cards region list
165 // by installing a self pointer.
166 HeapRegion* next = hr->get_next_dirty_cards_region();
167 if (next == NULL) {
168 HeapRegion* res = (HeapRegion*)
169 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
170 NULL);
171 if (res == NULL) {
172 HeapRegion* head;
173 do {
174 // Put the region to the dirty cards region list.
175 head = _dirty_cards_region_list;
176 next = (HeapRegion*)
177 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
178 if (next == head) {
179 assert(hr->get_next_dirty_cards_region() == hr,
180 "hr->get_next_dirty_cards_region() != hr");
181 if (next == NULL) {
182 // The last region in the list points to itself.
183 hr->set_next_dirty_cards_region(hr);
184 } else {
185 hr->set_next_dirty_cards_region(next);
186 }
187 }
188 } while (next != head);
189 }
190 }
191 }
192
193 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
194 {
195 HeapRegion* head;
196 HeapRegion* hr;
197 do {
198 head = _dirty_cards_region_list;
199 if (head == NULL) {
200 return NULL;
201 }
202 HeapRegion* new_head = head->get_next_dirty_cards_region();
203 if (head == new_head) {
204 // The last region.
205 new_head = NULL;
206 }
207 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
208 head);
209 } while (hr != head);
210 assert(hr != NULL, "invariant");
211 hr->set_next_dirty_cards_region(NULL);
212 return hr;
213 }
214
215 // Returns true if the reference points to an object that
216 // can move in an incremental collection.
217 bool G1CollectedHeap::is_scavengable(const void* p) {
218 HeapRegion* hr = heap_region_containing(p);
219 return !hr->is_pinned();
220 }
221
222 // Private methods.
223
224 HeapRegion*
225 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
226 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
227 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
228 if (!_secondary_free_list.is_empty()) {
229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
230 "secondary_free_list has %u entries",
231 _secondary_free_list.length());
232 // It looks as if there are free regions available on the
233 // secondary_free_list. Let's move them to the free_list and try
234 // again to allocate from it.
235 append_secondary_free_list();
236
237 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
238 "empty we should have moved at least one entry to the free_list");
239 HeapRegion* res = _hrm.allocate_free_region(is_old);
240 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
241 "allocated " HR_FORMAT " from secondary_free_list",
242 HR_FORMAT_PARAMS(res));
243 return res;
244 }
245
246 // Wait here until we get notified either when (a) there are no
247 // more free regions coming or (b) some regions have been moved on
248 // the secondary_free_list.
249 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
250 }
251
252 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
253 "could not allocate from secondary_free_list");
254 return NULL;
255 }
256
257 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
258 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
259 "the only time we use this to allocate a humongous region is "
260 "when we are allocating a single humongous region");
261
262 HeapRegion* res;
263 if (G1StressConcRegionFreeing) {
264 if (!_secondary_free_list.is_empty()) {
265 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
266 "forced to look at the secondary_free_list");
267 res = new_region_try_secondary_free_list(is_old);
268 if (res != NULL) {
269 return res;
270 }
271 }
272 }
273
274 res = _hrm.allocate_free_region(is_old);
275
276 if (res == NULL) {
277 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
278 "res == NULL, trying the secondary_free_list");
279 res = new_region_try_secondary_free_list(is_old);
280 }
281 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
282 // Currently, only attempts to allocate GC alloc regions set
283 // do_expand to true. So, we should only reach here during a
284 // safepoint. If this assumption changes we might have to
285 // reconsider the use of _expand_heap_after_alloc_failure.
286 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
287
288 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
289 word_size * HeapWordSize);
290
291 if (expand(word_size * HeapWordSize)) {
292 // Given that expand() succeeded in expanding the heap, and we
293 // always expand the heap by an amount aligned to the heap
294 // region size, the free list should in theory not be empty.
295 // In either case allocate_free_region() will check for NULL.
296 res = _hrm.allocate_free_region(is_old);
297 } else {
298 _expand_heap_after_alloc_failure = false;
299 }
300 }
301 return res;
302 }
303
304 HeapWord*
305 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
306 uint num_regions,
307 size_t word_size,
308 AllocationContext_t context) {
309 assert(first != G1_NO_HRM_INDEX, "pre-condition");
310 assert(is_humongous(word_size), "word_size should be humongous");
311 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
312
313 // Index of last region in the series.
314 uint last = first + num_regions - 1;
315
316 // We need to initialize the region(s) we just discovered. This is
317 // a bit tricky given that it can happen concurrently with
318 // refinement threads refining cards on these regions and
319 // potentially wanting to refine the BOT as they are scanning
320 // those cards (this can happen shortly after a cleanup; see CR
321 // 6991377). So we have to set up the region(s) carefully and in
322 // a specific order.
323
324 // The word size sum of all the regions we will allocate.
325 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
326 assert(word_size <= word_size_sum, "sanity");
327
328 // This will be the "starts humongous" region.
329 HeapRegion* first_hr = region_at(first);
330 // The header of the new object will be placed at the bottom of
331 // the first region.
332 HeapWord* new_obj = first_hr->bottom();
333 // This will be the new top of the new object.
334 HeapWord* obj_top = new_obj + word_size;
335
336 // First, we need to zero the header of the space that we will be
337 // allocating. When we update top further down, some refinement
338 // threads might try to scan the region. By zeroing the header we
339 // ensure that any thread that will try to scan the region will
340 // come across the zero klass word and bail out.
341 //
342 // NOTE: It would not have been correct to have used
343 // CollectedHeap::fill_with_object() and make the space look like
344 // an int array. The thread that is doing the allocation will
345 // later update the object header to a potentially different array
346 // type and, for a very short period of time, the klass and length
347 // fields will be inconsistent. This could cause a refinement
348 // thread to calculate the object size incorrectly.
349 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
350
351 // How many words we use for filler objects.
352 size_t word_fill_size = word_size_sum - word_size;
353
354 // How many words memory we "waste" which cannot hold a filler object.
355 size_t words_not_fillable = 0;
356
357 if (word_fill_size >= min_fill_size()) {
358 fill_with_objects(obj_top, word_fill_size);
359 } else if (word_fill_size > 0) {
360 // We have space to fill, but we cannot fit an object there.
361 words_not_fillable = word_fill_size;
362 word_fill_size = 0;
363 }
364
365 // We will set up the first region as "starts humongous". This
366 // will also update the BOT covering all the regions to reflect
367 // that there is a single object that starts at the bottom of the
368 // first region.
369 first_hr->set_starts_humongous(obj_top, word_fill_size);
370 first_hr->set_allocation_context(context);
371 // Then, if there are any, we will set up the "continues
372 // humongous" regions.
373 HeapRegion* hr = NULL;
374 for (uint i = first + 1; i <= last; ++i) {
375 hr = region_at(i);
376 hr->set_continues_humongous(first_hr);
377 hr->set_allocation_context(context);
378 }
379
380 // Up to this point no concurrent thread would have been able to
381 // do any scanning on any region in this series. All the top
382 // fields still point to bottom, so the intersection between
383 // [bottom,top] and [card_start,card_end] will be empty. Before we
384 // update the top fields, we'll do a storestore to make sure that
385 // no thread sees the update to top before the zeroing of the
386 // object header and the BOT initialization.
387 OrderAccess::storestore();
388
389 // Now, we will update the top fields of the "continues humongous"
390 // regions except the last one.
391 for (uint i = first; i < last; ++i) {
392 hr = region_at(i);
393 hr->set_top(hr->end());
394 }
395
396 hr = region_at(last);
397 // If we cannot fit a filler object, we must set top to the end
398 // of the humongous object, otherwise we cannot iterate the heap
399 // and the BOT will not be complete.
400 hr->set_top(hr->end() - words_not_fillable);
401
402 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
403 "obj_top should be in last region");
404
405 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
406
407 assert(words_not_fillable == 0 ||
408 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
409 "Miscalculation in humongous allocation");
410
411 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
412
413 for (uint i = first; i <= last; ++i) {
414 hr = region_at(i);
415 _humongous_set.add(hr);
416 _hr_printer.alloc(hr);
417 }
418
419 return new_obj;
420 }
421
422 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
423 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
424 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
425 }
426
427 // If could fit into free regions w/o expansion, try.
428 // Otherwise, if can expand, do so.
429 // Otherwise, if using ex regions might help, try with ex given back.
430 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
431 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
432
433 _verifier->verify_region_sets_optional();
434
435 uint first = G1_NO_HRM_INDEX;
436 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
437
438 if (obj_regions == 1) {
439 // Only one region to allocate, try to use a fast path by directly allocating
440 // from the free lists. Do not try to expand here, we will potentially do that
441 // later.
442 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
443 if (hr != NULL) {
444 first = hr->hrm_index();
445 }
446 } else {
447 // We can't allocate humongous regions spanning more than one region while
448 // cleanupComplete() is running, since some of the regions we find to be
449 // empty might not yet be added to the free list. It is not straightforward
450 // to know in which list they are on so that we can remove them. We only
451 // need to do this if we need to allocate more than one region to satisfy the
452 // current humongous allocation request. If we are only allocating one region
453 // we use the one-region region allocation code (see above), that already
454 // potentially waits for regions from the secondary free list.
455 wait_while_free_regions_coming();
456 append_secondary_free_list_if_not_empty_with_lock();
457
458 // Policy: Try only empty regions (i.e. already committed first). Maybe we
459 // are lucky enough to find some.
460 first = _hrm.find_contiguous_only_empty(obj_regions);
461 if (first != G1_NO_HRM_INDEX) {
462 _hrm.allocate_free_regions_starting_at(first, obj_regions);
463 }
464 }
465
466 if (first == G1_NO_HRM_INDEX) {
467 // Policy: We could not find enough regions for the humongous object in the
468 // free list. Look through the heap to find a mix of free and uncommitted regions.
469 // If so, try expansion.
470 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
471 if (first != G1_NO_HRM_INDEX) {
472 // We found something. Make sure these regions are committed, i.e. expand
473 // the heap. Alternatively we could do a defragmentation GC.
474 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
475 word_size * HeapWordSize);
476
477
478 _hrm.expand_at(first, obj_regions);
479 g1_policy()->record_new_heap_size(num_regions());
480
481 #ifdef ASSERT
482 for (uint i = first; i < first + obj_regions; ++i) {
483 HeapRegion* hr = region_at(i);
484 assert(hr->is_free(), "sanity");
485 assert(hr->is_empty(), "sanity");
486 assert(is_on_master_free_list(hr), "sanity");
487 }
488 #endif
489 _hrm.allocate_free_regions_starting_at(first, obj_regions);
490 } else {
491 // Policy: Potentially trigger a defragmentation GC.
492 }
493 }
494
495 HeapWord* result = NULL;
496 if (first != G1_NO_HRM_INDEX) {
497 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
498 word_size, context);
499 assert(result != NULL, "it should always return a valid result");
500
501 // A successful humongous object allocation changes the used space
502 // information of the old generation so we need to recalculate the
503 // sizes and update the jstat counters here.
504 g1mm()->update_sizes();
505 }
506
507 _verifier->verify_region_sets_optional();
508
509 return result;
510 }
511
512 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
513 assert_heap_not_locked_and_not_at_safepoint();
514 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
515
516 uint dummy_gc_count_before;
517 uint dummy_gclocker_retry_count = 0;
518 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
519 }
520
521 HeapWord*
522 G1CollectedHeap::mem_allocate(size_t word_size,
523 bool* gc_overhead_limit_was_exceeded) {
524 assert_heap_not_locked_and_not_at_safepoint();
525
526 // Loop until the allocation is satisfied, or unsatisfied after GC.
527 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
528 uint gc_count_before;
529
530 HeapWord* result = NULL;
531 if (!is_humongous(word_size)) {
532 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
533 } else {
534 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
535 }
536 if (result != NULL) {
537 return result;
538 }
539
540 // Create the garbage collection operation...
541 VM_G1CollectForAllocation op(gc_count_before, word_size);
542 op.set_allocation_context(AllocationContext::current());
543
544 // ...and get the VM thread to execute it.
545 VMThread::execute(&op);
546
547 if (op.prologue_succeeded() && op.pause_succeeded()) {
548 // If the operation was successful we'll return the result even
549 // if it is NULL. If the allocation attempt failed immediately
550 // after a Full GC, it's unlikely we'll be able to allocate now.
551 HeapWord* result = op.result();
552 if (result != NULL && !is_humongous(word_size)) {
553 // Allocations that take place on VM operations do not do any
554 // card dirtying and we have to do it here. We only have to do
555 // this for non-humongous allocations, though.
556 dirty_young_block(result, word_size);
557 }
558 return result;
559 } else {
560 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
561 return NULL;
562 }
563 assert(op.result() == NULL,
564 "the result should be NULL if the VM op did not succeed");
565 }
566
567 // Give a warning if we seem to be looping forever.
568 if ((QueuedAllocationWarningCount > 0) &&
569 (try_count % QueuedAllocationWarningCount == 0)) {
570 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
571 }
572 }
573
574 ShouldNotReachHere();
575 return NULL;
576 }
577
578 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
579 AllocationContext_t context,
580 uint* gc_count_before_ret,
581 uint* gclocker_retry_count_ret) {
582 // Make sure you read the note in attempt_allocation_humongous().
583
584 assert_heap_not_locked_and_not_at_safepoint();
585 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
586 "be called for humongous allocation requests");
587
588 // We should only get here after the first-level allocation attempt
589 // (attempt_allocation()) failed to allocate.
590
591 // We will loop until a) we manage to successfully perform the
592 // allocation or b) we successfully schedule a collection which
593 // fails to perform the allocation. b) is the only case when we'll
594 // return NULL.
595 HeapWord* result = NULL;
596 for (int try_count = 1; /* we'll return */; try_count += 1) {
597 bool should_try_gc;
598 uint gc_count_before;
599
600 {
601 MutexLockerEx x(Heap_lock);
602 result = _allocator->attempt_allocation_locked(word_size, context);
603 if (result != NULL) {
604 return result;
605 }
606
607 if (GCLocker::is_active_and_needs_gc()) {
608 if (g1_policy()->can_expand_young_list()) {
609 // No need for an ergo verbose message here,
610 // can_expand_young_list() does this when it returns true.
611 result = _allocator->attempt_allocation_force(word_size, context);
612 if (result != NULL) {
613 return result;
614 }
615 }
616 should_try_gc = false;
617 } else {
618 // The GCLocker may not be active but the GCLocker initiated
619 // GC may not yet have been performed (GCLocker::needs_gc()
620 // returns true). In this case we do not try this GC and
621 // wait until the GCLocker initiated GC is performed, and
622 // then retry the allocation.
623 if (GCLocker::needs_gc()) {
624 should_try_gc = false;
625 } else {
626 // Read the GC count while still holding the Heap_lock.
627 gc_count_before = total_collections();
628 should_try_gc = true;
629 }
630 }
631 }
632
633 if (should_try_gc) {
634 bool succeeded;
635 result = do_collection_pause(word_size, gc_count_before, &succeeded,
636 GCCause::_g1_inc_collection_pause);
637 if (result != NULL) {
638 assert(succeeded, "only way to get back a non-NULL result");
639 return result;
640 }
641
642 if (succeeded) {
643 // If we get here we successfully scheduled a collection which
644 // failed to allocate. No point in trying to allocate
645 // further. We'll just return NULL.
646 MutexLockerEx x(Heap_lock);
647 *gc_count_before_ret = total_collections();
648 return NULL;
649 }
650 } else {
651 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
652 MutexLockerEx x(Heap_lock);
653 *gc_count_before_ret = total_collections();
654 return NULL;
655 }
656 // The GCLocker is either active or the GCLocker initiated
657 // GC has not yet been performed. Stall until it is and
658 // then retry the allocation.
659 GCLocker::stall_until_clear();
660 (*gclocker_retry_count_ret) += 1;
661 }
662
663 // We can reach here if we were unsuccessful in scheduling a
664 // collection (because another thread beat us to it) or if we were
665 // stalled due to the GC locker. In either can we should retry the
666 // allocation attempt in case another thread successfully
667 // performed a collection and reclaimed enough space. We do the
668 // first attempt (without holding the Heap_lock) here and the
669 // follow-on attempt will be at the start of the next loop
670 // iteration (after taking the Heap_lock).
671 result = _allocator->attempt_allocation(word_size, context);
672 if (result != NULL) {
673 return result;
674 }
675
676 // Give a warning if we seem to be looping forever.
677 if ((QueuedAllocationWarningCount > 0) &&
678 (try_count % QueuedAllocationWarningCount == 0)) {
679 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
680 "retries %d times", try_count);
681 }
682 }
683
684 ShouldNotReachHere();
685 return NULL;
686 }
687
688 void G1CollectedHeap::begin_archive_alloc_range() {
689 assert_at_safepoint(true /* should_be_vm_thread */);
690 if (_archive_allocator == NULL) {
691 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
692 }
693 }
694
695 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
696 // Allocations in archive regions cannot be of a size that would be considered
697 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
698 // may be different at archive-restore time.
699 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
700 }
701
702 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
703 assert_at_safepoint(true /* should_be_vm_thread */);
704 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
705 if (is_archive_alloc_too_large(word_size)) {
706 return NULL;
707 }
708 return _archive_allocator->archive_mem_allocate(word_size);
709 }
710
711 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
712 size_t end_alignment_in_bytes) {
713 assert_at_safepoint(true /* should_be_vm_thread */);
714 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
715
716 // Call complete_archive to do the real work, filling in the MemRegion
717 // array with the archive regions.
718 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
719 delete _archive_allocator;
720 _archive_allocator = NULL;
721 }
722
723 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
724 assert(ranges != NULL, "MemRegion array NULL");
725 assert(count != 0, "No MemRegions provided");
726 MemRegion reserved = _hrm.reserved();
727 for (size_t i = 0; i < count; i++) {
728 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
729 return false;
730 }
731 }
732 return true;
733 }
734
735 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
736 assert(!is_init_completed(), "Expect to be called at JVM init time");
737 assert(ranges != NULL, "MemRegion array NULL");
738 assert(count != 0, "No MemRegions provided");
739 MutexLockerEx x(Heap_lock);
740
741 MemRegion reserved = _hrm.reserved();
742 HeapWord* prev_last_addr = NULL;
743 HeapRegion* prev_last_region = NULL;
744
745 // Temporarily disable pretouching of heap pages. This interface is used
746 // when mmap'ing archived heap data in, so pre-touching is wasted.
747 FlagSetting fs(AlwaysPreTouch, false);
748
749 // Enable archive object checking in G1MarkSweep. We have to let it know
750 // about each archive range, so that objects in those ranges aren't marked.
751 G1MarkSweep::enable_archive_object_check();
752
753 // For each specified MemRegion range, allocate the corresponding G1
754 // regions and mark them as archive regions. We expect the ranges in
755 // ascending starting address order, without overlap.
756 for (size_t i = 0; i < count; i++) {
757 MemRegion curr_range = ranges[i];
758 HeapWord* start_address = curr_range.start();
759 size_t word_size = curr_range.word_size();
760 HeapWord* last_address = curr_range.last();
761 size_t commits = 0;
762
763 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
764 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
765 p2i(start_address), p2i(last_address));
766 guarantee(start_address > prev_last_addr,
767 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
768 p2i(start_address), p2i(prev_last_addr));
769 prev_last_addr = last_address;
770
771 // Check for ranges that start in the same G1 region in which the previous
772 // range ended, and adjust the start address so we don't try to allocate
773 // the same region again. If the current range is entirely within that
774 // region, skip it, just adjusting the recorded top.
775 HeapRegion* start_region = _hrm.addr_to_region(start_address);
776 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
777 start_address = start_region->end();
778 if (start_address > last_address) {
779 increase_used(word_size * HeapWordSize);
780 start_region->set_top(last_address + 1);
781 continue;
782 }
783 start_region->set_top(start_address);
784 curr_range = MemRegion(start_address, last_address + 1);
785 start_region = _hrm.addr_to_region(start_address);
786 }
787
788 // Perform the actual region allocation, exiting if it fails.
789 // Then note how much new space we have allocated.
790 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
791 return false;
792 }
793 increase_used(word_size * HeapWordSize);
794 if (commits != 0) {
795 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
796 HeapRegion::GrainWords * HeapWordSize * commits);
797
798 }
799
800 // Mark each G1 region touched by the range as archive, add it to the old set,
801 // and set the allocation context and top.
802 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
803 HeapRegion* last_region = _hrm.addr_to_region(last_address);
804 prev_last_region = last_region;
805
806 while (curr_region != NULL) {
807 assert(curr_region->is_empty() && !curr_region->is_pinned(),
808 "Region already in use (index %u)", curr_region->hrm_index());
809 curr_region->set_allocation_context(AllocationContext::system());
810 curr_region->set_archive();
811 _hr_printer.alloc(curr_region);
812 _old_set.add(curr_region);
813 if (curr_region != last_region) {
814 curr_region->set_top(curr_region->end());
815 curr_region = _hrm.next_region_in_heap(curr_region);
816 } else {
817 curr_region->set_top(last_address + 1);
818 curr_region = NULL;
819 }
820 }
821
822 // Notify mark-sweep of the archive range.
823 G1MarkSweep::set_range_archive(curr_range, true);
824 }
825 return true;
826 }
827
828 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
829 assert(!is_init_completed(), "Expect to be called at JVM init time");
830 assert(ranges != NULL, "MemRegion array NULL");
831 assert(count != 0, "No MemRegions provided");
832 MemRegion reserved = _hrm.reserved();
833 HeapWord *prev_last_addr = NULL;
834 HeapRegion* prev_last_region = NULL;
835
836 // For each MemRegion, create filler objects, if needed, in the G1 regions
837 // that contain the address range. The address range actually within the
838 // MemRegion will not be modified. That is assumed to have been initialized
839 // elsewhere, probably via an mmap of archived heap data.
840 MutexLockerEx x(Heap_lock);
841 for (size_t i = 0; i < count; i++) {
842 HeapWord* start_address = ranges[i].start();
843 HeapWord* last_address = ranges[i].last();
844
845 assert(reserved.contains(start_address) && reserved.contains(last_address),
846 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
847 p2i(start_address), p2i(last_address));
848 assert(start_address > prev_last_addr,
849 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
850 p2i(start_address), p2i(prev_last_addr));
851
852 HeapRegion* start_region = _hrm.addr_to_region(start_address);
853 HeapRegion* last_region = _hrm.addr_to_region(last_address);
854 HeapWord* bottom_address = start_region->bottom();
855
856 // Check for a range beginning in the same region in which the
857 // previous one ended.
858 if (start_region == prev_last_region) {
859 bottom_address = prev_last_addr + 1;
860 }
861
862 // Verify that the regions were all marked as archive regions by
863 // alloc_archive_regions.
864 HeapRegion* curr_region = start_region;
865 while (curr_region != NULL) {
866 guarantee(curr_region->is_archive(),
867 "Expected archive region at index %u", curr_region->hrm_index());
868 if (curr_region != last_region) {
869 curr_region = _hrm.next_region_in_heap(curr_region);
870 } else {
871 curr_region = NULL;
872 }
873 }
874
875 prev_last_addr = last_address;
876 prev_last_region = last_region;
877
878 // Fill the memory below the allocated range with dummy object(s),
879 // if the region bottom does not match the range start, or if the previous
880 // range ended within the same G1 region, and there is a gap.
881 if (start_address != bottom_address) {
882 size_t fill_size = pointer_delta(start_address, bottom_address);
883 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
884 increase_used(fill_size * HeapWordSize);
885 }
886 }
887 }
888
889 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
890 uint* gc_count_before_ret,
891 uint* gclocker_retry_count_ret) {
892 assert_heap_not_locked_and_not_at_safepoint();
893 assert(!is_humongous(word_size), "attempt_allocation() should not "
894 "be called for humongous allocation requests");
895
896 AllocationContext_t context = AllocationContext::current();
897 HeapWord* result = _allocator->attempt_allocation(word_size, context);
898
899 if (result == NULL) {
900 result = attempt_allocation_slow(word_size,
901 context,
902 gc_count_before_ret,
903 gclocker_retry_count_ret);
904 }
905 assert_heap_not_locked();
906 if (result != NULL) {
907 dirty_young_block(result, word_size);
908 }
909 return result;
910 }
911
912 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
913 assert(!is_init_completed(), "Expect to be called at JVM init time");
914 assert(ranges != NULL, "MemRegion array NULL");
915 assert(count != 0, "No MemRegions provided");
916 MemRegion reserved = _hrm.reserved();
917 HeapWord* prev_last_addr = NULL;
918 HeapRegion* prev_last_region = NULL;
919 size_t size_used = 0;
920 size_t uncommitted_regions = 0;
921
922 // For each Memregion, free the G1 regions that constitute it, and
923 // notify mark-sweep that the range is no longer to be considered 'archive.'
924 MutexLockerEx x(Heap_lock);
925 for (size_t i = 0; i < count; i++) {
926 HeapWord* start_address = ranges[i].start();
927 HeapWord* last_address = ranges[i].last();
928
929 assert(reserved.contains(start_address) && reserved.contains(last_address),
930 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
931 p2i(start_address), p2i(last_address));
932 assert(start_address > prev_last_addr,
933 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
934 p2i(start_address), p2i(prev_last_addr));
935 size_used += ranges[i].byte_size();
936 prev_last_addr = last_address;
937
938 HeapRegion* start_region = _hrm.addr_to_region(start_address);
939 HeapRegion* last_region = _hrm.addr_to_region(last_address);
940
941 // Check for ranges that start in the same G1 region in which the previous
942 // range ended, and adjust the start address so we don't try to free
943 // the same region again. If the current range is entirely within that
944 // region, skip it.
945 if (start_region == prev_last_region) {
946 start_address = start_region->end();
947 if (start_address > last_address) {
948 continue;
949 }
950 start_region = _hrm.addr_to_region(start_address);
951 }
952 prev_last_region = last_region;
953
954 // After verifying that each region was marked as an archive region by
955 // alloc_archive_regions, set it free and empty and uncommit it.
956 HeapRegion* curr_region = start_region;
957 while (curr_region != NULL) {
958 guarantee(curr_region->is_archive(),
959 "Expected archive region at index %u", curr_region->hrm_index());
960 uint curr_index = curr_region->hrm_index();
961 _old_set.remove(curr_region);
962 curr_region->set_free();
963 curr_region->set_top(curr_region->bottom());
964 if (curr_region != last_region) {
965 curr_region = _hrm.next_region_in_heap(curr_region);
966 } else {
967 curr_region = NULL;
968 }
969 _hrm.shrink_at(curr_index, 1);
970 uncommitted_regions++;
971 }
972
973 // Notify mark-sweep that this is no longer an archive range.
974 G1MarkSweep::set_range_archive(ranges[i], false);
975 }
976
977 if (uncommitted_regions != 0) {
978 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
979 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
980 }
981 decrease_used(size_used);
982 }
983
984 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
985 uint* gc_count_before_ret,
986 uint* gclocker_retry_count_ret) {
987 // The structure of this method has a lot of similarities to
988 // attempt_allocation_slow(). The reason these two were not merged
989 // into a single one is that such a method would require several "if
990 // allocation is not humongous do this, otherwise do that"
991 // conditional paths which would obscure its flow. In fact, an early
992 // version of this code did use a unified method which was harder to
993 // follow and, as a result, it had subtle bugs that were hard to
994 // track down. So keeping these two methods separate allows each to
995 // be more readable. It will be good to keep these two in sync as
996 // much as possible.
997
998 assert_heap_not_locked_and_not_at_safepoint();
999 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1000 "should only be called for humongous allocations");
1001
1002 // Humongous objects can exhaust the heap quickly, so we should check if we
1003 // need to start a marking cycle at each humongous object allocation. We do
1004 // the check before we do the actual allocation. The reason for doing it
1005 // before the allocation is that we avoid having to keep track of the newly
1006 // allocated memory while we do a GC.
1007 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1008 word_size)) {
1009 collect(GCCause::_g1_humongous_allocation);
1010 }
1011
1012 // We will loop until a) we manage to successfully perform the
1013 // allocation or b) we successfully schedule a collection which
1014 // fails to perform the allocation. b) is the only case when we'll
1015 // return NULL.
1016 HeapWord* result = NULL;
1017 for (int try_count = 1; /* we'll return */; try_count += 1) {
1018 bool should_try_gc;
1019 uint gc_count_before;
1020
1021 {
1022 MutexLockerEx x(Heap_lock);
1023
1024 // Given that humongous objects are not allocated in young
1025 // regions, we'll first try to do the allocation without doing a
1026 // collection hoping that there's enough space in the heap.
1027 result = humongous_obj_allocate(word_size, AllocationContext::current());
1028 if (result != NULL) {
1029 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1030 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1031 return result;
1032 }
1033
1034 if (GCLocker::is_active_and_needs_gc()) {
1035 should_try_gc = false;
1036 } else {
1037 // The GCLocker may not be active but the GCLocker initiated
1038 // GC may not yet have been performed (GCLocker::needs_gc()
1039 // returns true). In this case we do not try this GC and
1040 // wait until the GCLocker initiated GC is performed, and
1041 // then retry the allocation.
1042 if (GCLocker::needs_gc()) {
1043 should_try_gc = false;
1044 } else {
1045 // Read the GC count while still holding the Heap_lock.
1046 gc_count_before = total_collections();
1047 should_try_gc = true;
1048 }
1049 }
1050 }
1051
1052 if (should_try_gc) {
1053 // If we failed to allocate the humongous object, we should try to
1054 // do a collection pause (if we're allowed) in case it reclaims
1055 // enough space for the allocation to succeed after the pause.
1056
1057 bool succeeded;
1058 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1059 GCCause::_g1_humongous_allocation);
1060 if (result != NULL) {
1061 assert(succeeded, "only way to get back a non-NULL result");
1062 return result;
1063 }
1064
1065 if (succeeded) {
1066 // If we get here we successfully scheduled a collection which
1067 // failed to allocate. No point in trying to allocate
1068 // further. We'll just return NULL.
1069 MutexLockerEx x(Heap_lock);
1070 *gc_count_before_ret = total_collections();
1071 return NULL;
1072 }
1073 } else {
1074 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1075 MutexLockerEx x(Heap_lock);
1076 *gc_count_before_ret = total_collections();
1077 return NULL;
1078 }
1079 // The GCLocker is either active or the GCLocker initiated
1080 // GC has not yet been performed. Stall until it is and
1081 // then retry the allocation.
1082 GCLocker::stall_until_clear();
1083 (*gclocker_retry_count_ret) += 1;
1084 }
1085
1086 // We can reach here if we were unsuccessful in scheduling a
1087 // collection (because another thread beat us to it) or if we were
1088 // stalled due to the GC locker. In either can we should retry the
1089 // allocation attempt in case another thread successfully
1090 // performed a collection and reclaimed enough space. Give a
1091 // warning if we seem to be looping forever.
1092
1093 if ((QueuedAllocationWarningCount > 0) &&
1094 (try_count % QueuedAllocationWarningCount == 0)) {
1095 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1096 "retries %d times", try_count);
1097 }
1098 }
1099
1100 ShouldNotReachHere();
1101 return NULL;
1102 }
1103
1104 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1105 AllocationContext_t context,
1106 bool expect_null_mutator_alloc_region) {
1107 assert_at_safepoint(true /* should_be_vm_thread */);
1108 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1109 "the current alloc region was unexpectedly found to be non-NULL");
1110
1111 if (!is_humongous(word_size)) {
1112 return _allocator->attempt_allocation_locked(word_size, context);
1113 } else {
1114 HeapWord* result = humongous_obj_allocate(word_size, context);
1115 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1116 collector_state()->set_initiate_conc_mark_if_possible(true);
1117 }
1118 return result;
1119 }
1120
1121 ShouldNotReachHere();
1122 }
1123
1124 class PostMCRemSetClearClosure: public HeapRegionClosure {
1125 G1CollectedHeap* _g1h;
1126 ModRefBarrierSet* _mr_bs;
1127 public:
1128 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1129 _g1h(g1h), _mr_bs(mr_bs) {}
1130
1131 bool doHeapRegion(HeapRegion* r) {
1132 HeapRegionRemSet* hrrs = r->rem_set();
1133
1134 _g1h->reset_gc_time_stamps(r);
1135
1136 if (r->is_continues_humongous()) {
1137 // We'll assert that the strong code root list and RSet is empty
1138 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1139 assert(hrrs->occupied() == 0, "RSet should be empty");
1140 } else {
1141 hrrs->clear();
1142 }
1143 // You might think here that we could clear just the cards
1144 // corresponding to the used region. But no: if we leave a dirty card
1145 // in a region we might allocate into, then it would prevent that card
1146 // from being enqueued, and cause it to be missed.
1147 // Re: the performance cost: we shouldn't be doing full GC anyway!
1148 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1149
1150 return false;
1151 }
1152 };
1153
1154 void G1CollectedHeap::clear_rsets_post_compaction() {
1155 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1156 heap_region_iterate(&rs_clear);
1157 }
1158
1159 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1160 G1CollectedHeap* _g1h;
1161 UpdateRSOopClosure _cl;
1162 public:
1163 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1164 _cl(g1->g1_rem_set(), worker_i),
1165 _g1h(g1)
1166 { }
1167
1168 bool doHeapRegion(HeapRegion* r) {
1169 if (!r->is_continues_humongous()) {
1170 _cl.set_from(r);
1171 r->oop_iterate(&_cl);
1172 }
1173 return false;
1174 }
1175 };
1176
1177 class ParRebuildRSTask: public AbstractGangTask {
1178 G1CollectedHeap* _g1;
1179 HeapRegionClaimer _hrclaimer;
1180
1181 public:
1182 ParRebuildRSTask(G1CollectedHeap* g1) :
1183 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1184
1185 void work(uint worker_id) {
1186 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1187 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1188 }
1189 };
1190
1191 class PostCompactionPrinterClosure: public HeapRegionClosure {
1192 private:
1193 G1HRPrinter* _hr_printer;
1194 public:
1195 bool doHeapRegion(HeapRegion* hr) {
1196 assert(!hr->is_young(), "not expecting to find young regions");
1197 _hr_printer->post_compaction(hr);
1198 return false;
1199 }
1200
1201 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1202 : _hr_printer(hr_printer) { }
1203 };
1204
1205 void G1CollectedHeap::print_hrm_post_compaction() {
1206 if (_hr_printer.is_active()) {
1207 PostCompactionPrinterClosure cl(hr_printer());
1208 heap_region_iterate(&cl);
1209 }
1210
1211 }
1212
1213 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1214 bool clear_all_soft_refs) {
1215 assert_at_safepoint(true /* should_be_vm_thread */);
1216
1217 if (GCLocker::check_active_before_gc()) {
1218 return false;
1219 }
1220
1221 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1222 gc_timer->register_gc_start();
1223
1224 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1225 GCIdMark gc_id_mark;
1226 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1227
1228 SvcGCMarker sgcm(SvcGCMarker::FULL);
1229 ResourceMark rm;
1230
1231 print_heap_before_gc();
1232 print_heap_regions();
1233 trace_heap_before_gc(gc_tracer);
1234
1235 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1236
1237 _verifier->verify_region_sets_optional();
1238
1239 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1240 collector_policy()->should_clear_all_soft_refs();
1241
1242 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1243
1244 {
1245 IsGCActiveMark x;
1246
1247 // Timing
1248 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1249 GCTraceCPUTime tcpu;
1250
1251 {
1252 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1253 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1254 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1255
1256 G1HeapTransition heap_transition(this);
1257 g1_policy()->record_full_collection_start();
1258
1259 // Note: When we have a more flexible GC logging framework that
1260 // allows us to add optional attributes to a GC log record we
1261 // could consider timing and reporting how long we wait in the
1262 // following two methods.
1263 wait_while_free_regions_coming();
1264 // If we start the compaction before the CM threads finish
1265 // scanning the root regions we might trip them over as we'll
1266 // be moving objects / updating references. So let's wait until
1267 // they are done. By telling them to abort, they should complete
1268 // early.
1269 _cm->root_regions()->abort();
1270 _cm->root_regions()->wait_until_scan_finished();
1271 append_secondary_free_list_if_not_empty_with_lock();
1272
1273 gc_prologue(true);
1274 increment_total_collections(true /* full gc */);
1275 increment_old_marking_cycles_started();
1276
1277 assert(used() == recalculate_used(), "Should be equal");
1278
1279 _verifier->verify_before_gc();
1280
1281 _verifier->check_bitmaps("Full GC Start");
1282 pre_full_gc_dump(gc_timer);
1283
1284 #if defined(COMPILER2) || INCLUDE_JVMCI
1285 DerivedPointerTable::clear();
1286 #endif
1287
1288 // Disable discovery and empty the discovered lists
1289 // for the CM ref processor.
1290 ref_processor_cm()->disable_discovery();
1291 ref_processor_cm()->abandon_partial_discovery();
1292 ref_processor_cm()->verify_no_references_recorded();
1293
1294 // Abandon current iterations of concurrent marking and concurrent
1295 // refinement, if any are in progress.
1296 concurrent_mark()->abort();
1297
1298 // Make sure we'll choose a new allocation region afterwards.
1299 _allocator->release_mutator_alloc_region();
1300 _allocator->abandon_gc_alloc_regions();
1301 g1_rem_set()->cleanupHRRS();
1302
1303 // We may have added regions to the current incremental collection
1304 // set between the last GC or pause and now. We need to clear the
1305 // incremental collection set and then start rebuilding it afresh
1306 // after this full GC.
1307 abandon_collection_set(collection_set()->inc_head());
1308 collection_set()->clear_incremental();
1309 collection_set()->stop_incremental_building();
1310
1311 tear_down_region_sets(false /* free_list_only */);
1312 collector_state()->set_gcs_are_young(true);
1313
1314 // See the comments in g1CollectedHeap.hpp and
1315 // G1CollectedHeap::ref_processing_init() about
1316 // how reference processing currently works in G1.
1317
1318 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1319 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1320
1321 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1322 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1323
1324 ref_processor_stw()->enable_discovery();
1325 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1326
1327 // Do collection work
1328 {
1329 HandleMark hm; // Discard invalid handles created during gc
1330 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1331 }
1332
1333 assert(num_free_regions() == 0, "we should not have added any free regions");
1334 rebuild_region_sets(false /* free_list_only */);
1335
1336 // Enqueue any discovered reference objects that have
1337 // not been removed from the discovered lists.
1338 ref_processor_stw()->enqueue_discovered_references();
1339
1340 #if defined(COMPILER2) || INCLUDE_JVMCI
1341 DerivedPointerTable::update_pointers();
1342 #endif
1343
1344 MemoryService::track_memory_usage();
1345
1346 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1347 ref_processor_stw()->verify_no_references_recorded();
1348
1349 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1350 ClassLoaderDataGraph::purge();
1351 MetaspaceAux::verify_metrics();
1352
1353 // Note: since we've just done a full GC, concurrent
1354 // marking is no longer active. Therefore we need not
1355 // re-enable reference discovery for the CM ref processor.
1356 // That will be done at the start of the next marking cycle.
1357 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1358 ref_processor_cm()->verify_no_references_recorded();
1359
1360 reset_gc_time_stamp();
1361 // Since everything potentially moved, we will clear all remembered
1362 // sets, and clear all cards. Later we will rebuild remembered
1363 // sets. We will also reset the GC time stamps of the regions.
1364 clear_rsets_post_compaction();
1365 check_gc_time_stamps();
1366
1367 resize_if_necessary_after_full_collection();
1368
1369 // We should do this after we potentially resize the heap so
1370 // that all the COMMIT / UNCOMMIT events are generated before
1371 // the compaction events.
1372 print_hrm_post_compaction();
1373
1374 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1375 if (hot_card_cache->use_cache()) {
1376 hot_card_cache->reset_card_counts();
1377 hot_card_cache->reset_hot_cache();
1378 }
1379
1380 // Rebuild remembered sets of all regions.
1381 uint n_workers =
1382 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1383 workers()->active_workers(),
1384 Threads::number_of_non_daemon_threads());
1385 workers()->set_active_workers(n_workers);
1386
1387 ParRebuildRSTask rebuild_rs_task(this);
1388 workers()->run_task(&rebuild_rs_task);
1389
1390 // Rebuild the strong code root lists for each region
1391 rebuild_strong_code_roots();
1392
1393 if (true) { // FIXME
1394 MetaspaceGC::compute_new_size();
1395 }
1396
1397 #ifdef TRACESPINNING
1398 ParallelTaskTerminator::print_termination_counts();
1399 #endif
1400
1401 // Discard all rset updates
1402 JavaThread::dirty_card_queue_set().abandon_logs();
1403 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1404
1405 // At this point there should be no regions in the
1406 // entire heap tagged as young.
1407 assert(check_young_list_empty(true /* check_heap */),
1408 "young list should be empty at this point");
1409
1410 // Update the number of full collections that have been completed.
1411 increment_old_marking_cycles_completed(false /* concurrent */);
1412
1413 _hrm.verify_optional();
1414 _verifier->verify_region_sets_optional();
1415
1416 _verifier->verify_after_gc();
1417
1418 // Clear the previous marking bitmap, if needed for bitmap verification.
1419 // Note we cannot do this when we clear the next marking bitmap in
1420 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1421 // objects marked during a full GC against the previous bitmap.
1422 // But we need to clear it before calling check_bitmaps below since
1423 // the full GC has compacted objects and updated TAMS but not updated
1424 // the prev bitmap.
1425 if (G1VerifyBitmaps) {
1426 ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1427 }
1428 _verifier->check_bitmaps("Full GC End");
1429
1430 // Start a new incremental collection set for the next pause
1431 assert(collection_set()->head() == NULL, "must be");
1432 collection_set()->start_incremental_building();
1433
1434 clear_cset_fast_test();
1435
1436 _allocator->init_mutator_alloc_region();
1437
1438 g1_policy()->record_full_collection_end();
1439
1440 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1441 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1442 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1443 // before any GC notifications are raised.
1444 g1mm()->update_sizes();
1445
1446 gc_epilogue(true);
1447
1448 heap_transition.print();
1449
1450 print_heap_after_gc();
1451 print_heap_regions();
1452 trace_heap_after_gc(gc_tracer);
1453
1454 post_full_gc_dump(gc_timer);
1455 }
1456
1457 gc_timer->register_gc_end();
1458 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1459 }
1460
1461 return true;
1462 }
1463
1464 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1465 // Currently, there is no facility in the do_full_collection(bool) API to notify
1466 // the caller that the collection did not succeed (e.g., because it was locked
1467 // out by the GC locker). So, right now, we'll ignore the return value.
1468 bool dummy = do_full_collection(true, /* explicit_gc */
1469 clear_all_soft_refs);
1470 }
1471
1472 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1473 // Include bytes that will be pre-allocated to support collections, as "used".
1474 const size_t used_after_gc = used();
1475 const size_t capacity_after_gc = capacity();
1476 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1477
1478 // This is enforced in arguments.cpp.
1479 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1480 "otherwise the code below doesn't make sense");
1481
1482 // We don't have floating point command-line arguments
1483 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1484 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1485 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1486 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1487
1488 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1489 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1490
1491 // We have to be careful here as these two calculations can overflow
1492 // 32-bit size_t's.
1493 double used_after_gc_d = (double) used_after_gc;
1494 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1495 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1496
1497 // Let's make sure that they are both under the max heap size, which
1498 // by default will make them fit into a size_t.
1499 double desired_capacity_upper_bound = (double) max_heap_size;
1500 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1501 desired_capacity_upper_bound);
1502 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1503 desired_capacity_upper_bound);
1504
1505 // We can now safely turn them into size_t's.
1506 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1507 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1508
1509 // This assert only makes sense here, before we adjust them
1510 // with respect to the min and max heap size.
1511 assert(minimum_desired_capacity <= maximum_desired_capacity,
1512 "minimum_desired_capacity = " SIZE_FORMAT ", "
1513 "maximum_desired_capacity = " SIZE_FORMAT,
1514 minimum_desired_capacity, maximum_desired_capacity);
1515
1516 // Should not be greater than the heap max size. No need to adjust
1517 // it with respect to the heap min size as it's a lower bound (i.e.,
1518 // we'll try to make the capacity larger than it, not smaller).
1519 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1520 // Should not be less than the heap min size. No need to adjust it
1521 // with respect to the heap max size as it's an upper bound (i.e.,
1522 // we'll try to make the capacity smaller than it, not greater).
1523 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1524
1525 if (capacity_after_gc < minimum_desired_capacity) {
1526 // Don't expand unless it's significant
1527 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1528
1529 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1530 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1531 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1532
1533 expand(expand_bytes);
1534
1535 // No expansion, now see if we want to shrink
1536 } else if (capacity_after_gc > maximum_desired_capacity) {
1537 // Capacity too large, compute shrinking size
1538 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1539
1540 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1541 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1542 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1543
1544 shrink(shrink_bytes);
1545 }
1546 }
1547
1548 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1549 AllocationContext_t context,
1550 bool do_gc,
1551 bool clear_all_soft_refs,
1552 bool expect_null_mutator_alloc_region,
1553 bool* gc_succeeded) {
1554 *gc_succeeded = true;
1555 // Let's attempt the allocation first.
1556 HeapWord* result =
1557 attempt_allocation_at_safepoint(word_size,
1558 context,
1559 expect_null_mutator_alloc_region);
1560 if (result != NULL) {
1561 assert(*gc_succeeded, "sanity");
1562 return result;
1563 }
1564
1565 // In a G1 heap, we're supposed to keep allocation from failing by
1566 // incremental pauses. Therefore, at least for now, we'll favor
1567 // expansion over collection. (This might change in the future if we can
1568 // do something smarter than full collection to satisfy a failed alloc.)
1569 result = expand_and_allocate(word_size, context);
1570 if (result != NULL) {
1571 assert(*gc_succeeded, "sanity");
1572 return result;
1573 }
1574
1575 if (do_gc) {
1576 // Expansion didn't work, we'll try to do a Full GC.
1577 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1578 clear_all_soft_refs);
1579 }
1580
1581 return NULL;
1582 }
1583
1584 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1585 AllocationContext_t context,
1586 bool* succeeded) {
1587 assert_at_safepoint(true /* should_be_vm_thread */);
1588
1589 // Attempts to allocate followed by Full GC.
1590 HeapWord* result =
1591 satisfy_failed_allocation_helper(word_size,
1592 context,
1593 true, /* do_gc */
1594 false, /* clear_all_soft_refs */
1595 false, /* expect_null_mutator_alloc_region */
1596 succeeded);
1597
1598 if (result != NULL || !*succeeded) {
1599 return result;
1600 }
1601
1602 // Attempts to allocate followed by Full GC that will collect all soft references.
1603 result = satisfy_failed_allocation_helper(word_size,
1604 context,
1605 true, /* do_gc */
1606 true, /* clear_all_soft_refs */
1607 true, /* expect_null_mutator_alloc_region */
1608 succeeded);
1609
1610 if (result != NULL || !*succeeded) {
1611 return result;
1612 }
1613
1614 // Attempts to allocate, no GC
1615 result = satisfy_failed_allocation_helper(word_size,
1616 context,
1617 false, /* do_gc */
1618 false, /* clear_all_soft_refs */
1619 true, /* expect_null_mutator_alloc_region */
1620 succeeded);
1621
1622 if (result != NULL) {
1623 assert(*succeeded, "sanity");
1624 return result;
1625 }
1626
1627 assert(!collector_policy()->should_clear_all_soft_refs(),
1628 "Flag should have been handled and cleared prior to this point");
1629
1630 // What else? We might try synchronous finalization later. If the total
1631 // space available is large enough for the allocation, then a more
1632 // complete compaction phase than we've tried so far might be
1633 // appropriate.
1634 assert(*succeeded, "sanity");
1635 return NULL;
1636 }
1637
1638 // Attempting to expand the heap sufficiently
1639 // to support an allocation of the given "word_size". If
1640 // successful, perform the allocation and return the address of the
1641 // allocated block, or else "NULL".
1642
1643 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1644 assert_at_safepoint(true /* should_be_vm_thread */);
1645
1646 _verifier->verify_region_sets_optional();
1647
1648 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1649 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1650 word_size * HeapWordSize);
1651
1652
1653 if (expand(expand_bytes)) {
1654 _hrm.verify_optional();
1655 _verifier->verify_region_sets_optional();
1656 return attempt_allocation_at_safepoint(word_size,
1657 context,
1658 false /* expect_null_mutator_alloc_region */);
1659 }
1660 return NULL;
1661 }
1662
1663 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1664 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1665 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1666 HeapRegion::GrainBytes);
1667
1668 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1669 expand_bytes, aligned_expand_bytes);
1670
1671 if (is_maximal_no_gc()) {
1672 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1673 return false;
1674 }
1675
1676 double expand_heap_start_time_sec = os::elapsedTime();
1677 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1678 assert(regions_to_expand > 0, "Must expand by at least one region");
1679
1680 uint expanded_by = _hrm.expand_by(regions_to_expand);
1681 if (expand_time_ms != NULL) {
1682 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1683 }
1684
1685 if (expanded_by > 0) {
1686 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1687 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1688 g1_policy()->record_new_heap_size(num_regions());
1689 } else {
1690 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1691
1692 // The expansion of the virtual storage space was unsuccessful.
1693 // Let's see if it was because we ran out of swap.
1694 if (G1ExitOnExpansionFailure &&
1695 _hrm.available() >= regions_to_expand) {
1696 // We had head room...
1697 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1698 }
1699 }
1700 return regions_to_expand > 0;
1701 }
1702
1703 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1704 size_t aligned_shrink_bytes =
1705 ReservedSpace::page_align_size_down(shrink_bytes);
1706 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1707 HeapRegion::GrainBytes);
1708 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1709
1710 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1711 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1712
1713
1714 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",
1715 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1716 if (num_regions_removed > 0) {
1717 g1_policy()->record_new_heap_size(num_regions());
1718 } else {
1719 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1720 }
1721 }
1722
1723 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1724 _verifier->verify_region_sets_optional();
1725
1726 // We should only reach here at the end of a Full GC which means we
1727 // should not not be holding to any GC alloc regions. The method
1728 // below will make sure of that and do any remaining clean up.
1729 _allocator->abandon_gc_alloc_regions();
1730
1731 // Instead of tearing down / rebuilding the free lists here, we
1732 // could instead use the remove_all_pending() method on free_list to
1733 // remove only the ones that we need to remove.
1734 tear_down_region_sets(true /* free_list_only */);
1735 shrink_helper(shrink_bytes);
1736 rebuild_region_sets(true /* free_list_only */);
1737
1738 _hrm.verify_optional();
1739 _verifier->verify_region_sets_optional();
1740 }
1741
1742 // Public methods.
1743
1744 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1745 CollectedHeap(),
1746 _g1_policy(policy_),
1747 _collection_set(this),
1748 _dirty_card_queue_set(false),
1749 _is_alive_closure_cm(this),
1750 _is_alive_closure_stw(this),
1751 _ref_processor_cm(NULL),
1752 _ref_processor_stw(NULL),
1753 _bot(NULL),
1754 _cg1r(NULL),
1755 _g1mm(NULL),
1756 _refine_cte_cl(NULL),
1757 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1758 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1759 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1760 _humongous_reclaim_candidates(),
1761 _has_humongous_reclaim_candidates(false),
1762 _archive_allocator(NULL),
1763 _free_regions_coming(false),
1764 _young_list(new YoungList(this)),
1765 _gc_time_stamp(0),
1766 _summary_bytes_used(0),
1767 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1768 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1769 _expand_heap_after_alloc_failure(true),
1770 _old_marking_cycles_started(0),
1771 _old_marking_cycles_completed(0),
1772 _heap_summary_sent(false),
1773 _in_cset_fast_test(),
1774 _dirty_cards_region_list(NULL),
1775 _worker_cset_start_region(NULL),
1776 _worker_cset_start_region_time_stamp(NULL),
1777 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1778 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1779 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1780 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
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 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1790
1791 // Override the default _filler_array_max_size so that no humongous filler
1792 // objects are created.
1793 _filler_array_max_size = _humongous_object_threshold_in_words;
1794
1795 uint n_queues = ParallelGCThreads;
1796 _task_queues = new RefToScanQueueSet(n_queues);
1797
1798 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1799 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1800 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1801
1802 for (uint i = 0; i < n_queues; i++) {
1803 RefToScanQueue* q = new RefToScanQueue();
1804 q->initialize();
1805 _task_queues->register_queue(i, q);
1806 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1807 }
1808 clear_cset_start_regions();
1809
1810 // Initialize the G1EvacuationFailureALot counters and flags.
1811 NOT_PRODUCT(reset_evacuation_should_fail();)
1812
1813 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1814 }
1815
1816 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1817 size_t size,
1818 size_t translation_factor) {
1819 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1820 // Allocate a new reserved space, preferring to use large pages.
1821 ReservedSpace rs(size, preferred_page_size);
1822 G1RegionToSpaceMapper* result =
1823 G1RegionToSpaceMapper::create_mapper(rs,
1824 size,
1825 rs.alignment(),
1826 HeapRegion::GrainBytes,
1827 translation_factor,
1828 mtGC);
1829 if (TracePageSizes) {
1830 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1831 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1832 }
1833 return result;
1834 }
1835
1836 jint G1CollectedHeap::initialize() {
1837 CollectedHeap::pre_initialize();
1838 os::enable_vtime();
1839
1840 // Necessary to satisfy locking discipline assertions.
1841
1842 MutexLocker x(Heap_lock);
1843
1844 // While there are no constraints in the GC code that HeapWordSize
1845 // be any particular value, there are multiple other areas in the
1846 // system which believe this to be true (e.g. oop->object_size in some
1847 // cases incorrectly returns the size in wordSize units rather than
1848 // HeapWordSize).
1849 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1850
1851 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1852 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1853 size_t heap_alignment = collector_policy()->heap_alignment();
1854
1855 // Ensure that the sizes are properly aligned.
1856 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1857 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1858 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1859
1860 _refine_cte_cl = new RefineCardTableEntryClosure();
1861
1862 jint ecode = JNI_OK;
1863 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1864 if (_cg1r == NULL) {
1865 return ecode;
1866 }
1867
1868 // Reserve the maximum.
1869
1870 // When compressed oops are enabled, the preferred heap base
1871 // is calculated by subtracting the requested size from the
1872 // 32Gb boundary and using the result as the base address for
1873 // heap reservation. If the requested size is not aligned to
1874 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1875 // into the ReservedHeapSpace constructor) then the actual
1876 // base of the reserved heap may end up differing from the
1877 // address that was requested (i.e. the preferred heap base).
1878 // If this happens then we could end up using a non-optimal
1879 // compressed oops mode.
1880
1881 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1882 heap_alignment);
1883
1884 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1885
1886 // Create the barrier set for the entire reserved region.
1887 G1SATBCardTableLoggingModRefBS* bs
1888 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1889 bs->initialize();
1890 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1891 set_barrier_set(bs);
1892
1893 // Also create a G1 rem set.
1894 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1895
1896 // Carve out the G1 part of the heap.
1897 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1898 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1899 G1RegionToSpaceMapper* heap_storage =
1900 G1RegionToSpaceMapper::create_mapper(g1_rs,
1901 g1_rs.size(),
1902 page_size,
1903 HeapRegion::GrainBytes,
1904 1,
1905 mtJavaHeap);
1906 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1907 max_byte_size, page_size,
1908 heap_rs.base(),
1909 heap_rs.size());
1910 heap_storage->set_mapping_changed_listener(&_listener);
1911
1912 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1913 G1RegionToSpaceMapper* bot_storage =
1914 create_aux_memory_mapper("Block offset table",
1915 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1916 G1BlockOffsetTable::heap_map_factor());
1917
1918 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1919 G1RegionToSpaceMapper* cardtable_storage =
1920 create_aux_memory_mapper("Card table",
1921 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1922 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1923
1924 G1RegionToSpaceMapper* card_counts_storage =
1925 create_aux_memory_mapper("Card counts table",
1926 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1927 G1CardCounts::heap_map_factor());
1928
1929 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1930 G1RegionToSpaceMapper* prev_bitmap_storage =
1931 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1932 G1RegionToSpaceMapper* next_bitmap_storage =
1933 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1934
1935 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1936 g1_barrier_set()->initialize(cardtable_storage);
1937 // Do later initialization work for concurrent refinement.
1938 _cg1r->init(card_counts_storage);
1939
1940 // 6843694 - ensure that the maximum region index can fit
1941 // in the remembered set structures.
1942 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1943 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1944
1945 G1RemSet::initialize(max_regions());
1946
1947 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1948 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1949 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1950 "too many cards per region");
1951
1952 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1953
1954 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1955
1956 {
1957 HeapWord* start = _hrm.reserved().start();
1958 HeapWord* end = _hrm.reserved().end();
1959 size_t granularity = HeapRegion::GrainBytes;
1960
1961 _in_cset_fast_test.initialize(start, end, granularity);
1962 _humongous_reclaim_candidates.initialize(start, end, granularity);
1963 }
1964
1965 // Create the G1ConcurrentMark data structure and thread.
1966 // (Must do this late, so that "max_regions" is defined.)
1967 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1968 if (_cm == NULL || !_cm->completed_initialization()) {
1969 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1970 return JNI_ENOMEM;
1971 }
1972 _cmThread = _cm->cmThread();
1973
1974 // Now expand into the initial heap size.
1975 if (!expand(init_byte_size)) {
1976 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1977 return JNI_ENOMEM;
1978 }
1979
1980 // Perform any initialization actions delegated to the policy.
1981 g1_policy()->init();
1982
1983 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1984 SATB_Q_FL_lock,
1985 G1SATBProcessCompletedThreshold,
1986 Shared_SATB_Q_lock);
1987
1988 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1989 DirtyCardQ_CBL_mon,
1990 DirtyCardQ_FL_lock,
1991 (int)concurrent_g1_refine()->yellow_zone(),
1992 (int)concurrent_g1_refine()->red_zone(),
1993 Shared_DirtyCardQ_lock,
1994 NULL, // fl_owner
1995 true); // init_free_ids
1996
1997 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1998 DirtyCardQ_CBL_mon,
1999 DirtyCardQ_FL_lock,
2000 -1, // never trigger processing
2001 -1, // no limit on length
2002 Shared_DirtyCardQ_lock,
2003 &JavaThread::dirty_card_queue_set());
2004
2005 // Here we allocate the dummy HeapRegion that is required by the
2006 // G1AllocRegion class.
2007 HeapRegion* dummy_region = _hrm.get_dummy_region();
2008
2009 // We'll re-use the same region whether the alloc region will
2010 // require BOT updates or not and, if it doesn't, then a non-young
2011 // region will complain that it cannot support allocations without
2012 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2013 dummy_region->set_eden();
2014 // Make sure it's full.
2015 dummy_region->set_top(dummy_region->end());
2016 G1AllocRegion::setup(this, dummy_region);
2017
2018 _allocator->init_mutator_alloc_region();
2019
2020 // Do create of the monitoring and management support so that
2021 // values in the heap have been properly initialized.
2022 _g1mm = new G1MonitoringSupport(this);
2023
2024 G1StringDedup::initialize();
2025
2026 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2027 for (uint i = 0; i < ParallelGCThreads; i++) {
2028 new (&_preserved_objs[i]) OopAndMarkOopStack();
2029 }
2030
2031 return JNI_OK;
2032 }
2033
2034 void G1CollectedHeap::stop() {
2035 // Stop all concurrent threads. We do this to make sure these threads
2036 // do not continue to execute and access resources (e.g. logging)
2037 // that are destroyed during shutdown.
2038 _cg1r->stop();
2039 _cmThread->stop();
2040 if (G1StringDedup::is_enabled()) {
2041 G1StringDedup::stop();
2042 }
2043 }
2044
2045 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2046 return HeapRegion::max_region_size();
2047 }
2048
2049 void G1CollectedHeap::post_initialize() {
2050 CollectedHeap::post_initialize();
2051 ref_processing_init();
2052 }
2053
2054 void G1CollectedHeap::ref_processing_init() {
2055 // Reference processing in G1 currently works as follows:
2056 //
2057 // * There are two reference processor instances. One is
2058 // used to record and process discovered references
2059 // during concurrent marking; the other is used to
2060 // record and process references during STW pauses
2061 // (both full and incremental).
2062 // * Both ref processors need to 'span' the entire heap as
2063 // the regions in the collection set may be dotted around.
2064 //
2065 // * For the concurrent marking ref processor:
2066 // * Reference discovery is enabled at initial marking.
2067 // * Reference discovery is disabled and the discovered
2068 // references processed etc during remarking.
2069 // * Reference discovery is MT (see below).
2070 // * Reference discovery requires a barrier (see below).
2071 // * Reference processing may or may not be MT
2072 // (depending on the value of ParallelRefProcEnabled
2073 // and ParallelGCThreads).
2074 // * A full GC disables reference discovery by the CM
2075 // ref processor and abandons any entries on it's
2076 // discovered lists.
2077 //
2078 // * For the STW processor:
2079 // * Non MT discovery is enabled at the start of a full GC.
2080 // * Processing and enqueueing during a full GC is non-MT.
2081 // * During a full GC, references are processed after marking.
2082 //
2083 // * Discovery (may or may not be MT) is enabled at the start
2084 // of an incremental evacuation pause.
2085 // * References are processed near the end of a STW evacuation pause.
2086 // * For both types of GC:
2087 // * Discovery is atomic - i.e. not concurrent.
2088 // * Reference discovery will not need a barrier.
2089
2090 MemRegion mr = reserved_region();
2091
2092 // Concurrent Mark ref processor
2093 _ref_processor_cm =
2094 new ReferenceProcessor(mr, // span
2095 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2096 // mt processing
2097 ParallelGCThreads,
2098 // degree of mt processing
2099 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2100 // mt discovery
2101 MAX2(ParallelGCThreads, ConcGCThreads),
2102 // degree of mt discovery
2103 false,
2104 // Reference discovery is not atomic
2105 &_is_alive_closure_cm);
2106 // is alive closure
2107 // (for efficiency/performance)
2108
2109 // STW ref processor
2110 _ref_processor_stw =
2111 new ReferenceProcessor(mr, // span
2112 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2113 // mt processing
2114 ParallelGCThreads,
2115 // degree of mt processing
2116 (ParallelGCThreads > 1),
2117 // mt discovery
2118 ParallelGCThreads,
2119 // degree of mt discovery
2120 true,
2121 // Reference discovery is atomic
2122 &_is_alive_closure_stw);
2123 // is alive closure
2124 // (for efficiency/performance)
2125 }
2126
2127 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2128 return g1_policy();
2129 }
2130
2131 size_t G1CollectedHeap::capacity() const {
2132 return _hrm.length() * HeapRegion::GrainBytes;
2133 }
2134
2135 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2136 hr->reset_gc_time_stamp();
2137 }
2138
2139 #ifndef PRODUCT
2140
2141 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2142 private:
2143 unsigned _gc_time_stamp;
2144 bool _failures;
2145
2146 public:
2147 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2148 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2149
2150 virtual bool doHeapRegion(HeapRegion* hr) {
2151 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2152 if (_gc_time_stamp != region_gc_time_stamp) {
2153 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2154 region_gc_time_stamp, _gc_time_stamp);
2155 _failures = true;
2156 }
2157 return false;
2158 }
2159
2160 bool failures() { return _failures; }
2161 };
2162
2163 void G1CollectedHeap::check_gc_time_stamps() {
2164 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2165 heap_region_iterate(&cl);
2166 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2167 }
2168 #endif // PRODUCT
2169
2170 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2171 _cg1r->hot_card_cache()->drain(cl, worker_i);
2172 }
2173
2174 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2175 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2176 size_t n_completed_buffers = 0;
2177 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2178 n_completed_buffers++;
2179 }
2180 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2181 dcqs.clear_n_completed_buffers();
2182 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2183 }
2184
2185 // Computes the sum of the storage used by the various regions.
2186 size_t G1CollectedHeap::used() const {
2187 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2188 if (_archive_allocator != NULL) {
2189 result += _archive_allocator->used();
2190 }
2191 return result;
2192 }
2193
2194 size_t G1CollectedHeap::used_unlocked() const {
2195 return _summary_bytes_used;
2196 }
2197
2198 class SumUsedClosure: public HeapRegionClosure {
2199 size_t _used;
2200 public:
2201 SumUsedClosure() : _used(0) {}
2202 bool doHeapRegion(HeapRegion* r) {
2203 _used += r->used();
2204 return false;
2205 }
2206 size_t result() { return _used; }
2207 };
2208
2209 size_t G1CollectedHeap::recalculate_used() const {
2210 double recalculate_used_start = os::elapsedTime();
2211
2212 SumUsedClosure blk;
2213 heap_region_iterate(&blk);
2214
2215 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2216 return blk.result();
2217 }
2218
2219 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2220 switch (cause) {
2221 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2222 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2223 case GCCause::_update_allocation_context_stats_inc: return true;
2224 case GCCause::_wb_conc_mark: return true;
2225 default : return false;
2226 }
2227 }
2228
2229 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2230 switch (cause) {
2231 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2232 case GCCause::_g1_humongous_allocation: return true;
2233 default: return is_user_requested_concurrent_full_gc(cause);
2234 }
2235 }
2236
2237 #ifndef PRODUCT
2238 void G1CollectedHeap::allocate_dummy_regions() {
2239 // Let's fill up most of the region
2240 size_t word_size = HeapRegion::GrainWords - 1024;
2241 // And as a result the region we'll allocate will be humongous.
2242 guarantee(is_humongous(word_size), "sanity");
2243
2244 // _filler_array_max_size is set to humongous object threshold
2245 // but temporarily change it to use CollectedHeap::fill_with_object().
2246 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2247
2248 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2249 // Let's use the existing mechanism for the allocation
2250 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2251 AllocationContext::system());
2252 if (dummy_obj != NULL) {
2253 MemRegion mr(dummy_obj, word_size);
2254 CollectedHeap::fill_with_object(mr);
2255 } else {
2256 // If we can't allocate once, we probably cannot allocate
2257 // again. Let's get out of the loop.
2258 break;
2259 }
2260 }
2261 }
2262 #endif // !PRODUCT
2263
2264 void G1CollectedHeap::increment_old_marking_cycles_started() {
2265 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2266 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2267 "Wrong marking cycle count (started: %d, completed: %d)",
2268 _old_marking_cycles_started, _old_marking_cycles_completed);
2269
2270 _old_marking_cycles_started++;
2271 }
2272
2273 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2274 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2275
2276 // We assume that if concurrent == true, then the caller is a
2277 // concurrent thread that was joined the Suspendible Thread
2278 // Set. If there's ever a cheap way to check this, we should add an
2279 // assert here.
2280
2281 // Given that this method is called at the end of a Full GC or of a
2282 // concurrent cycle, and those can be nested (i.e., a Full GC can
2283 // interrupt a concurrent cycle), the number of full collections
2284 // completed should be either one (in the case where there was no
2285 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2286 // behind the number of full collections started.
2287
2288 // This is the case for the inner caller, i.e. a Full GC.
2289 assert(concurrent ||
2290 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2291 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2292 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2293 "is inconsistent with _old_marking_cycles_completed = %u",
2294 _old_marking_cycles_started, _old_marking_cycles_completed);
2295
2296 // This is the case for the outer caller, i.e. the concurrent cycle.
2297 assert(!concurrent ||
2298 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2299 "for outer caller (concurrent cycle): "
2300 "_old_marking_cycles_started = %u "
2301 "is inconsistent with _old_marking_cycles_completed = %u",
2302 _old_marking_cycles_started, _old_marking_cycles_completed);
2303
2304 _old_marking_cycles_completed += 1;
2305
2306 // We need to clear the "in_progress" flag in the CM thread before
2307 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2308 // is set) so that if a waiter requests another System.gc() it doesn't
2309 // incorrectly see that a marking cycle is still in progress.
2310 if (concurrent) {
2311 _cmThread->set_idle();
2312 }
2313
2314 // This notify_all() will ensure that a thread that called
2315 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2316 // and it's waiting for a full GC to finish will be woken up. It is
2317 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2318 FullGCCount_lock->notify_all();
2319 }
2320
2321 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2322 GCIdMarkAndRestore conc_gc_id_mark;
2323 collector_state()->set_concurrent_cycle_started(true);
2324 _gc_timer_cm->register_gc_start(start_time);
2325
2326 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2327 trace_heap_before_gc(_gc_tracer_cm);
2328 _cmThread->set_gc_id(GCId::current());
2329 }
2330
2331 void G1CollectedHeap::register_concurrent_cycle_end() {
2332 if (collector_state()->concurrent_cycle_started()) {
2333 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2334 if (_cm->has_aborted()) {
2335 _gc_tracer_cm->report_concurrent_mode_failure();
2336
2337 // ConcurrentGCTimer will be ended as well.
2338 _cm->register_concurrent_gc_end_and_stop_timer();
2339 } else {
2340 _gc_timer_cm->register_gc_end();
2341 }
2342
2343 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2344
2345 // Clear state variables to prepare for the next concurrent cycle.
2346 collector_state()->set_concurrent_cycle_started(false);
2347 _heap_summary_sent = false;
2348 }
2349 }
2350
2351 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2352 if (collector_state()->concurrent_cycle_started()) {
2353 // This function can be called when:
2354 // the cleanup pause is run
2355 // the concurrent cycle is aborted before the cleanup pause.
2356 // the concurrent cycle is aborted after the cleanup pause,
2357 // but before the concurrent cycle end has been registered.
2358 // Make sure that we only send the heap information once.
2359 if (!_heap_summary_sent) {
2360 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2361 trace_heap_after_gc(_gc_tracer_cm);
2362 _heap_summary_sent = true;
2363 }
2364 }
2365 }
2366
2367 void G1CollectedHeap::collect(GCCause::Cause cause) {
2368 assert_heap_not_locked();
2369
2370 uint gc_count_before;
2371 uint old_marking_count_before;
2372 uint full_gc_count_before;
2373 bool retry_gc;
2374
2375 do {
2376 retry_gc = false;
2377
2378 {
2379 MutexLocker ml(Heap_lock);
2380
2381 // Read the GC count while holding the Heap_lock
2382 gc_count_before = total_collections();
2383 full_gc_count_before = total_full_collections();
2384 old_marking_count_before = _old_marking_cycles_started;
2385 }
2386
2387 if (should_do_concurrent_full_gc(cause)) {
2388 // Schedule an initial-mark evacuation pause that will start a
2389 // concurrent cycle. We're setting word_size to 0 which means that
2390 // we are not requesting a post-GC allocation.
2391 VM_G1IncCollectionPause op(gc_count_before,
2392 0, /* word_size */
2393 true, /* should_initiate_conc_mark */
2394 g1_policy()->max_pause_time_ms(),
2395 cause);
2396 op.set_allocation_context(AllocationContext::current());
2397
2398 VMThread::execute(&op);
2399 if (!op.pause_succeeded()) {
2400 if (old_marking_count_before == _old_marking_cycles_started) {
2401 retry_gc = op.should_retry_gc();
2402 } else {
2403 // A Full GC happened while we were trying to schedule the
2404 // initial-mark GC. No point in starting a new cycle given
2405 // that the whole heap was collected anyway.
2406 }
2407
2408 if (retry_gc) {
2409 if (GCLocker::is_active_and_needs_gc()) {
2410 GCLocker::stall_until_clear();
2411 }
2412 }
2413 }
2414 } else {
2415 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2416 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2417
2418 // Schedule a standard evacuation pause. We're setting word_size
2419 // to 0 which means that we are not requesting a post-GC allocation.
2420 VM_G1IncCollectionPause op(gc_count_before,
2421 0, /* word_size */
2422 false, /* should_initiate_conc_mark */
2423 g1_policy()->max_pause_time_ms(),
2424 cause);
2425 VMThread::execute(&op);
2426 } else {
2427 // Schedule a Full GC.
2428 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2429 VMThread::execute(&op);
2430 }
2431 }
2432 } while (retry_gc);
2433 }
2434
2435 bool G1CollectedHeap::is_in(const void* p) const {
2436 if (_hrm.reserved().contains(p)) {
2437 // Given that we know that p is in the reserved space,
2438 // heap_region_containing() should successfully
2439 // return the containing region.
2440 HeapRegion* hr = heap_region_containing(p);
2441 return hr->is_in(p);
2442 } else {
2443 return false;
2444 }
2445 }
2446
2447 #ifdef ASSERT
2448 bool G1CollectedHeap::is_in_exact(const void* p) const {
2449 bool contains = reserved_region().contains(p);
2450 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2451 if (contains && available) {
2452 return true;
2453 } else {
2454 return false;
2455 }
2456 }
2457 #endif
2458
2459 bool G1CollectedHeap::obj_in_cs(oop obj) {
2460 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2461 return r != NULL && r->in_collection_set();
2462 }
2463
2464 // Iteration functions.
2465
2466 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2467
2468 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2469 ExtendedOopClosure* _cl;
2470 public:
2471 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2472 bool doHeapRegion(HeapRegion* r) {
2473 if (!r->is_continues_humongous()) {
2474 r->oop_iterate(_cl);
2475 }
2476 return false;
2477 }
2478 };
2479
2480 // Iterates an ObjectClosure over all objects within a HeapRegion.
2481
2482 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2483 ObjectClosure* _cl;
2484 public:
2485 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2486 bool doHeapRegion(HeapRegion* r) {
2487 if (!r->is_continues_humongous()) {
2488 r->object_iterate(_cl);
2489 }
2490 return false;
2491 }
2492 };
2493
2494 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2495 IterateObjectClosureRegionClosure blk(cl);
2496 heap_region_iterate(&blk);
2497 }
2498
2499 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2500 _hrm.iterate(cl);
2501 }
2502
2503 void
2504 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2505 uint worker_id,
2506 HeapRegionClaimer *hrclaimer,
2507 bool concurrent) const {
2508 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2509 }
2510
2511 // Clear the cached CSet starting regions and (more importantly)
2512 // the time stamps. Called when we reset the GC time stamp.
2513 void G1CollectedHeap::clear_cset_start_regions() {
2514 assert(_worker_cset_start_region != NULL, "sanity");
2515 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2516
2517 for (uint i = 0; i < ParallelGCThreads; i++) {
2518 _worker_cset_start_region[i] = NULL;
2519 _worker_cset_start_region_time_stamp[i] = 0;
2520 }
2521 }
2522
2523 // Given the id of a worker, obtain or calculate a suitable
2524 // starting region for iterating over the current collection set.
2525 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2526 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2527
2528 HeapRegion* result = NULL;
2529 unsigned gc_time_stamp = get_gc_time_stamp();
2530
2531 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2532 // Cached starting region for current worker was set
2533 // during the current pause - so it's valid.
2534 // Note: the cached starting heap region may be NULL
2535 // (when the collection set is empty).
2536 result = _worker_cset_start_region[worker_i];
2537 assert(result == NULL || result->in_collection_set(), "sanity");
2538 return result;
2539 }
2540
2541 // The cached entry was not valid so let's calculate
2542 // a suitable starting heap region for this worker.
2543
2544 // We want the parallel threads to start their collection
2545 // set iteration at different collection set regions to
2546 // avoid contention.
2547 // If we have:
2548 // n collection set regions
2549 // p threads
2550 // Then thread t will start at region floor ((t * n) / p)
2551
2552 result = collection_set()->head();
2553 uint cs_size = collection_set()->region_length();
2554 uint active_workers = workers()->active_workers();
2555
2556 uint end_ind = (cs_size * worker_i) / active_workers;
2557 uint start_ind = 0;
2558
2559 if (worker_i > 0 &&
2560 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2561 // Previous workers starting region is valid
2562 // so let's iterate from there
2563 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2564 OrderAccess::loadload();
2565 result = _worker_cset_start_region[worker_i - 1];
2566 }
2567
2568 for (uint i = start_ind; i < end_ind; i++) {
2569 result = result->next_in_collection_set();
2570 }
2571
2572 // Note: the calculated starting heap region may be NULL
2573 // (when the collection set is empty).
2574 assert(result == NULL || result->in_collection_set(), "sanity");
2575 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2576 "should be updated only once per pause");
2577 _worker_cset_start_region[worker_i] = result;
2578 OrderAccess::storestore();
2579 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2580 return result;
2581 }
2582
2583 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2584 HeapRegion* r = collection_set()->head();
2585 while (r != NULL) {
2586 HeapRegion* next = r->next_in_collection_set();
2587 if (cl->doHeapRegion(r)) {
2588 cl->incomplete();
2589 return;
2590 }
2591 r = next;
2592 }
2593 }
2594
2595 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2596 HeapRegionClosure *cl) {
2597 if (r == NULL) {
2598 // The CSet is empty so there's nothing to do.
2599 return;
2600 }
2601
2602 assert(r->in_collection_set(),
2603 "Start region must be a member of the collection set.");
2604 HeapRegion* cur = r;
2605 while (cur != NULL) {
2606 HeapRegion* next = cur->next_in_collection_set();
2607 if (cl->doHeapRegion(cur) && false) {
2608 cl->incomplete();
2609 return;
2610 }
2611 cur = next;
2612 }
2613 cur = collection_set()->head();
2614 while (cur != r) {
2615 HeapRegion* next = cur->next_in_collection_set();
2616 if (cl->doHeapRegion(cur) && false) {
2617 cl->incomplete();
2618 return;
2619 }
2620 cur = next;
2621 }
2622 }
2623
2624 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2625 HeapRegion* result = _hrm.next_region_in_heap(from);
2626 while (result != NULL && result->is_pinned()) {
2627 result = _hrm.next_region_in_heap(result);
2628 }
2629 return result;
2630 }
2631
2632 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2633 HeapRegion* hr = heap_region_containing(addr);
2634 return hr->block_start(addr);
2635 }
2636
2637 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2638 HeapRegion* hr = heap_region_containing(addr);
2639 return hr->block_size(addr);
2640 }
2641
2642 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2643 HeapRegion* hr = heap_region_containing(addr);
2644 return hr->block_is_obj(addr);
2645 }
2646
2647 bool G1CollectedHeap::supports_tlab_allocation() const {
2648 return true;
2649 }
2650
2651 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2652 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2653 }
2654
2655 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2656 return young_list()->eden_used_bytes();
2657 }
2658
2659 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2660 // must be equal to the humongous object limit.
2661 size_t G1CollectedHeap::max_tlab_size() const {
2662 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2663 }
2664
2665 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2666 AllocationContext_t context = AllocationContext::current();
2667 return _allocator->unsafe_max_tlab_alloc(context);
2668 }
2669
2670 size_t G1CollectedHeap::max_capacity() const {
2671 return _hrm.reserved().byte_size();
2672 }
2673
2674 jlong G1CollectedHeap::millis_since_last_gc() {
2675 // assert(false, "NYI");
2676 return 0;
2677 }
2678
2679 void G1CollectedHeap::prepare_for_verify() {
2680 _verifier->prepare_for_verify();
2681 }
2682
2683 void G1CollectedHeap::verify(VerifyOption vo) {
2684 _verifier->verify(vo);
2685 }
2686
2687 class PrintRegionClosure: public HeapRegionClosure {
2688 outputStream* _st;
2689 public:
2690 PrintRegionClosure(outputStream* st) : _st(st) {}
2691 bool doHeapRegion(HeapRegion* r) {
2692 r->print_on(_st);
2693 return false;
2694 }
2695 };
2696
2697 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2698 const HeapRegion* hr,
2699 const VerifyOption vo) const {
2700 switch (vo) {
2701 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2702 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2703 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2704 default: ShouldNotReachHere();
2705 }
2706 return false; // keep some compilers happy
2707 }
2708
2709 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2710 const VerifyOption vo) const {
2711 switch (vo) {
2712 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2713 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2714 case VerifyOption_G1UseMarkWord: {
2715 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2716 return !obj->is_gc_marked() && !hr->is_archive();
2717 }
2718 default: ShouldNotReachHere();
2719 }
2720 return false; // keep some compilers happy
2721 }
2722
2723 void G1CollectedHeap::print_heap_regions() const {
2724 LogHandle(gc, heap, region) log;
2725 if (log.is_trace()) {
2726 ResourceMark rm;
2727 print_regions_on(log.trace_stream());
2728 }
2729 }
2730
2731 void G1CollectedHeap::print_on(outputStream* st) const {
2732 st->print(" %-20s", "garbage-first heap");
2733 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2734 capacity()/K, used_unlocked()/K);
2735 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2736 p2i(_hrm.reserved().start()),
2737 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2738 p2i(_hrm.reserved().end()));
2739 st->cr();
2740 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2741 uint young_regions = _young_list->length();
2742 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2743 (size_t) young_regions * HeapRegion::GrainBytes / K);
2744 uint survivor_regions = _young_list->survivor_length();
2745 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2746 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2747 st->cr();
2748 MetaspaceAux::print_on(st);
2749 }
2750
2751 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2752 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2753 "HS=humongous(starts), HC=humongous(continues), "
2754 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2755 "AC=allocation context, "
2756 "TAMS=top-at-mark-start (previous, next)");
2757 PrintRegionClosure blk(st);
2758 heap_region_iterate(&blk);
2759 }
2760
2761 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2762 print_on(st);
2763
2764 // Print the per-region information.
2765 print_regions_on(st);
2766 }
2767
2768 void G1CollectedHeap::print_on_error(outputStream* st) const {
2769 this->CollectedHeap::print_on_error(st);
2770
2771 if (_cm != NULL) {
2772 st->cr();
2773 _cm->print_on_error(st);
2774 }
2775 }
2776
2777 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2778 workers()->print_worker_threads_on(st);
2779 _cmThread->print_on(st);
2780 st->cr();
2781 _cm->print_worker_threads_on(st);
2782 _cg1r->print_worker_threads_on(st);
2783 if (G1StringDedup::is_enabled()) {
2784 G1StringDedup::print_worker_threads_on(st);
2785 }
2786 }
2787
2788 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2789 workers()->threads_do(tc);
2790 tc->do_thread(_cmThread);
2791 _cg1r->threads_do(tc);
2792 if (G1StringDedup::is_enabled()) {
2793 G1StringDedup::threads_do(tc);
2794 }
2795 }
2796
2797 void G1CollectedHeap::print_tracing_info() const {
2798 g1_rem_set()->print_summary_info();
2799 concurrent_mark()->print_summary_info();
2800 g1_policy()->print_yg_surv_rate_info();
2801 }
2802
2803 #ifndef PRODUCT
2804 // Helpful for debugging RSet issues.
2805
2806 class PrintRSetsClosure : public HeapRegionClosure {
2807 private:
2808 const char* _msg;
2809 size_t _occupied_sum;
2810
2811 public:
2812 bool doHeapRegion(HeapRegion* r) {
2813 HeapRegionRemSet* hrrs = r->rem_set();
2814 size_t occupied = hrrs->occupied();
2815 _occupied_sum += occupied;
2816
2817 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2818 if (occupied == 0) {
2819 tty->print_cr(" RSet is empty");
2820 } else {
2821 hrrs->print();
2822 }
2823 tty->print_cr("----------");
2824 return false;
2825 }
2826
2827 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2828 tty->cr();
2829 tty->print_cr("========================================");
2830 tty->print_cr("%s", msg);
2831 tty->cr();
2832 }
2833
2834 ~PrintRSetsClosure() {
2835 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2836 tty->print_cr("========================================");
2837 tty->cr();
2838 }
2839 };
2840
2841 void G1CollectedHeap::print_cset_rsets() {
2842 PrintRSetsClosure cl("Printing CSet RSets");
2843 collection_set_iterate(&cl);
2844 }
2845
2846 void G1CollectedHeap::print_all_rsets() {
2847 PrintRSetsClosure cl("Printing All RSets");;
2848 heap_region_iterate(&cl);
2849 }
2850 #endif // PRODUCT
2851
2852 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2853 YoungList* young_list = heap()->young_list();
2854
2855 size_t eden_used_bytes = young_list->eden_used_bytes();
2856 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2857
2858 size_t eden_capacity_bytes =
2859 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2860
2861 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2862 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions());
2863 }
2864
2865 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2866 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2867 stats->unused(), stats->used(), stats->region_end_waste(),
2868 stats->regions_filled(), stats->direct_allocated(),
2869 stats->failure_used(), stats->failure_waste());
2870 }
2871
2872 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2873 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2874 gc_tracer->report_gc_heap_summary(when, heap_summary);
2875
2876 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2877 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2878 }
2879
2880
2881 G1CollectedHeap* G1CollectedHeap::heap() {
2882 CollectedHeap* heap = Universe::heap();
2883 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2884 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2885 return (G1CollectedHeap*)heap;
2886 }
2887
2888 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2889 // always_do_update_barrier = false;
2890 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2891 // Fill TLAB's and such
2892 accumulate_statistics_all_tlabs();
2893 ensure_parsability(true);
2894
2895 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2896 }
2897
2898 void G1CollectedHeap::gc_epilogue(bool full) {
2899 // we are at the end of the GC. Total collections has already been increased.
2900 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2901
2902 // FIXME: what is this about?
2903 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2904 // is set.
2905 #if defined(COMPILER2) || INCLUDE_JVMCI
2906 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2907 #endif
2908 // always_do_update_barrier = true;
2909
2910 resize_all_tlabs();
2911 allocation_context_stats().update(full);
2912
2913 // We have just completed a GC. Update the soft reference
2914 // policy with the new heap occupancy
2915 Universe::update_heap_info_at_gc();
2916 }
2917
2918 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2919 uint gc_count_before,
2920 bool* succeeded,
2921 GCCause::Cause gc_cause) {
2922 assert_heap_not_locked_and_not_at_safepoint();
2923 VM_G1IncCollectionPause op(gc_count_before,
2924 word_size,
2925 false, /* should_initiate_conc_mark */
2926 g1_policy()->max_pause_time_ms(),
2927 gc_cause);
2928
2929 op.set_allocation_context(AllocationContext::current());
2930 VMThread::execute(&op);
2931
2932 HeapWord* result = op.result();
2933 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2934 assert(result == NULL || ret_succeeded,
2935 "the result should be NULL if the VM did not succeed");
2936 *succeeded = ret_succeeded;
2937
2938 assert_heap_not_locked();
2939 return result;
2940 }
2941
2942 void
2943 G1CollectedHeap::doConcurrentMark() {
2944 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2945 if (!_cmThread->in_progress()) {
2946 _cmThread->set_started();
2947 CGC_lock->notify();
2948 }
2949 }
2950
2951 size_t G1CollectedHeap::pending_card_num() {
2952 size_t extra_cards = 0;
2953 JavaThread *curr = Threads::first();
2954 while (curr != NULL) {
2955 DirtyCardQueue& dcq = curr->dirty_card_queue();
2956 extra_cards += dcq.size();
2957 curr = curr->next();
2958 }
2959 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2960 size_t buffer_size = dcqs.buffer_size();
2961 size_t buffer_num = dcqs.completed_buffers_num();
2962
2963 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2964 // in bytes - not the number of 'entries'. We need to convert
2965 // into a number of cards.
2966 return (buffer_size * buffer_num + extra_cards) / oopSize;
2967 }
2968
2969 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2970 private:
2971 size_t _total_humongous;
2972 size_t _candidate_humongous;
2973
2974 DirtyCardQueue _dcq;
2975
2976 // We don't nominate objects with many remembered set entries, on
2977 // the assumption that such objects are likely still live.
2978 bool is_remset_small(HeapRegion* region) const {
2979 HeapRegionRemSet* const rset = region->rem_set();
2980 return G1EagerReclaimHumongousObjectsWithStaleRefs
2981 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2982 : rset->is_empty();
2983 }
2984
2985 bool is_typeArray_region(HeapRegion* region) const {
2986 return oop(region->bottom())->is_typeArray();
2987 }
2988
2989 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2990 assert(region->is_starts_humongous(), "Must start a humongous object");
2991
2992 // Candidate selection must satisfy the following constraints
2993 // while concurrent marking is in progress:
2994 //
2995 // * In order to maintain SATB invariants, an object must not be
2996 // reclaimed if it was allocated before the start of marking and
2997 // has not had its references scanned. Such an object must have
2998 // its references (including type metadata) scanned to ensure no
2999 // live objects are missed by the marking process. Objects
3000 // allocated after the start of concurrent marking don't need to
3001 // be scanned.
3002 //
3003 // * An object must not be reclaimed if it is on the concurrent
3004 // mark stack. Objects allocated after the start of concurrent
3005 // marking are never pushed on the mark stack.
3006 //
3007 // Nominating only objects allocated after the start of concurrent
3008 // marking is sufficient to meet both constraints. This may miss
3009 // some objects that satisfy the constraints, but the marking data
3010 // structures don't support efficiently performing the needed
3011 // additional tests or scrubbing of the mark stack.
3012 //
3013 // However, we presently only nominate is_typeArray() objects.
3014 // A humongous object containing references induces remembered
3015 // set entries on other regions. In order to reclaim such an
3016 // object, those remembered sets would need to be cleaned up.
3017 //
3018 // We also treat is_typeArray() objects specially, allowing them
3019 // to be reclaimed even if allocated before the start of
3020 // concurrent mark. For this we rely on mark stack insertion to
3021 // exclude is_typeArray() objects, preventing reclaiming an object
3022 // that is in the mark stack. We also rely on the metadata for
3023 // such objects to be built-in and so ensured to be kept live.
3024 // Frequent allocation and drop of large binary blobs is an
3025 // important use case for eager reclaim, and this special handling
3026 // may reduce needed headroom.
3027
3028 return is_typeArray_region(region) && is_remset_small(region);
3029 }
3030
3031 public:
3032 RegisterHumongousWithInCSetFastTestClosure()
3033 : _total_humongous(0),
3034 _candidate_humongous(0),
3035 _dcq(&JavaThread::dirty_card_queue_set()) {
3036 }
3037
3038 virtual bool doHeapRegion(HeapRegion* r) {
3039 if (!r->is_starts_humongous()) {
3040 return false;
3041 }
3042 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3043
3044 bool is_candidate = humongous_region_is_candidate(g1h, r);
3045 uint rindex = r->hrm_index();
3046 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3047 if (is_candidate) {
3048 _candidate_humongous++;
3049 g1h->register_humongous_region_with_cset(rindex);
3050 // Is_candidate already filters out humongous object with large remembered sets.
3051 // If we have a humongous object with a few remembered sets, we simply flush these
3052 // remembered set entries into the DCQS. That will result in automatic
3053 // re-evaluation of their remembered set entries during the following evacuation
3054 // phase.
3055 if (!r->rem_set()->is_empty()) {
3056 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3057 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3058 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3059 HeapRegionRemSetIterator hrrs(r->rem_set());
3060 size_t card_index;
3061 while (hrrs.has_next(card_index)) {
3062 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3063 // The remembered set might contain references to already freed
3064 // regions. Filter out such entries to avoid failing card table
3065 // verification.
3066 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3067 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3068 *card_ptr = CardTableModRefBS::dirty_card_val();
3069 _dcq.enqueue(card_ptr);
3070 }
3071 }
3072 }
3073 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3074 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3075 hrrs.n_yielded(), r->rem_set()->occupied());
3076 r->rem_set()->clear_locked();
3077 }
3078 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3079 }
3080 _total_humongous++;
3081
3082 return false;
3083 }
3084
3085 size_t total_humongous() const { return _total_humongous; }
3086 size_t candidate_humongous() const { return _candidate_humongous; }
3087
3088 void flush_rem_set_entries() { _dcq.flush(); }
3089 };
3090
3091 void G1CollectedHeap::register_humongous_regions_with_cset() {
3092 if (!G1EagerReclaimHumongousObjects) {
3093 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3094 return;
3095 }
3096 double time = os::elapsed_counter();
3097
3098 // Collect reclaim candidate information and register candidates with cset.
3099 RegisterHumongousWithInCSetFastTestClosure cl;
3100 heap_region_iterate(&cl);
3101
3102 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3103 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3104 cl.total_humongous(),
3105 cl.candidate_humongous());
3106 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3107
3108 // Finally flush all remembered set entries to re-check into the global DCQS.
3109 cl.flush_rem_set_entries();
3110 }
3111
3112 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3113 public:
3114 bool doHeapRegion(HeapRegion* hr) {
3115 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3116 hr->verify_rem_set();
3117 }
3118 return false;
3119 }
3120 };
3121
3122 #ifdef ASSERT
3123 class VerifyCSetClosure: public HeapRegionClosure {
3124 public:
3125 bool doHeapRegion(HeapRegion* hr) {
3126 // Here we check that the CSet region's RSet is ready for parallel
3127 // iteration. The fields that we'll verify are only manipulated
3128 // when the region is part of a CSet and is collected. Afterwards,
3129 // we reset these fields when we clear the region's RSet (when the
3130 // region is freed) so they are ready when the region is
3131 // re-allocated. The only exception to this is if there's an
3132 // evacuation failure and instead of freeing the region we leave
3133 // it in the heap. In that case, we reset these fields during
3134 // evacuation failure handling.
3135 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3136
3137 // Here's a good place to add any other checks we'd like to
3138 // perform on CSet regions.
3139 return false;
3140 }
3141 };
3142 #endif // ASSERT
3143
3144 uint G1CollectedHeap::num_task_queues() const {
3145 return _task_queues->size();
3146 }
3147
3148 #if TASKQUEUE_STATS
3149 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3150 st->print_raw_cr("GC Task Stats");
3151 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3152 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3153 }
3154
3155 void G1CollectedHeap::print_taskqueue_stats() const {
3156 if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3157 return;
3158 }
3159 LogHandle(gc, task, stats) log;
3160 ResourceMark rm;
3161 outputStream* st = log.trace_stream();
3162
3163 print_taskqueue_stats_hdr(st);
3164
3165 TaskQueueStats totals;
3166 const uint n = num_task_queues();
3167 for (uint i = 0; i < n; ++i) {
3168 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3169 totals += task_queue(i)->stats;
3170 }
3171 st->print_raw("tot "); totals.print(st); st->cr();
3172
3173 DEBUG_ONLY(totals.verify());
3174 }
3175
3176 void G1CollectedHeap::reset_taskqueue_stats() {
3177 const uint n = num_task_queues();
3178 for (uint i = 0; i < n; ++i) {
3179 task_queue(i)->stats.reset();
3180 }
3181 }
3182 #endif // TASKQUEUE_STATS
3183
3184 void G1CollectedHeap::wait_for_root_region_scanning() {
3185 double scan_wait_start = os::elapsedTime();
3186 // We have to wait until the CM threads finish scanning the
3187 // root regions as it's the only way to ensure that all the
3188 // objects on them have been correctly scanned before we start
3189 // moving them during the GC.
3190 bool waited = _cm->root_regions()->wait_until_scan_finished();
3191 double wait_time_ms = 0.0;
3192 if (waited) {
3193 double scan_wait_end = os::elapsedTime();
3194 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3195 }
3196 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3197 }
3198
3199 bool
3200 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3201 assert_at_safepoint(true /* should_be_vm_thread */);
3202 guarantee(!is_gc_active(), "collection is not reentrant");
3203
3204 if (GCLocker::check_active_before_gc()) {
3205 return false;
3206 }
3207
3208 _gc_timer_stw->register_gc_start();
3209
3210 GCIdMark gc_id_mark;
3211 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3212
3213 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3214 ResourceMark rm;
3215
3216 wait_for_root_region_scanning();
3217
3218 print_heap_before_gc();
3219 print_heap_regions();
3220 trace_heap_before_gc(_gc_tracer_stw);
3221
3222 _verifier->verify_region_sets_optional();
3223 _verifier->verify_dirty_young_regions();
3224
3225 // This call will decide whether this pause is an initial-mark
3226 // pause. If it is, during_initial_mark_pause() will return true
3227 // for the duration of this pause.
3228 g1_policy()->decide_on_conc_mark_initiation();
3229
3230 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3231 assert(!collector_state()->during_initial_mark_pause() ||
3232 collector_state()->gcs_are_young(), "sanity");
3233
3234 // We also do not allow mixed GCs during marking.
3235 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3236
3237 // Record whether this pause is an initial mark. When the current
3238 // thread has completed its logging output and it's safe to signal
3239 // the CM thread, the flag's value in the policy has been reset.
3240 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3241
3242 // Inner scope for scope based logging, timers, and stats collection
3243 {
3244 EvacuationInfo evacuation_info;
3245
3246 if (collector_state()->during_initial_mark_pause()) {
3247 // We are about to start a marking cycle, so we increment the
3248 // full collection counter.
3249 increment_old_marking_cycles_started();
3250 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3251 }
3252
3253 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3254
3255 GCTraceCPUTime tcpu;
3256
3257 FormatBuffer<> gc_string("Pause ");
3258 if (collector_state()->during_initial_mark_pause()) {
3259 gc_string.append("Initial Mark");
3260 } else if (collector_state()->gcs_are_young()) {
3261 gc_string.append("Young");
3262 } else {
3263 gc_string.append("Mixed");
3264 }
3265 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3266
3267 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3268 workers()->active_workers(),
3269 Threads::number_of_non_daemon_threads());
3270 workers()->set_active_workers(active_workers);
3271
3272 g1_policy()->note_gc_start(active_workers);
3273
3274 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3275 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3276
3277 // If the secondary_free_list is not empty, append it to the
3278 // free_list. No need to wait for the cleanup operation to finish;
3279 // the region allocation code will check the secondary_free_list
3280 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3281 // set, skip this step so that the region allocation code has to
3282 // get entries from the secondary_free_list.
3283 if (!G1StressConcRegionFreeing) {
3284 append_secondary_free_list_if_not_empty_with_lock();
3285 }
3286
3287 G1HeapTransition heap_transition(this);
3288 size_t heap_used_bytes_before_gc = used();
3289
3290 assert(check_young_list_well_formed(), "young list should be well formed");
3291
3292 // Don't dynamically change the number of GC threads this early. A value of
3293 // 0 is used to indicate serial work. When parallel work is done,
3294 // it will be set.
3295
3296 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3297 IsGCActiveMark x;
3298
3299 gc_prologue(false);
3300 increment_total_collections(false /* full gc */);
3301 increment_gc_time_stamp();
3302
3303 if (VerifyRememberedSets) {
3304 log_info(gc, verify)("[Verifying RemSets before GC]");
3305 VerifyRegionRemSetClosure v_cl;
3306 heap_region_iterate(&v_cl);
3307 }
3308
3309 _verifier->verify_before_gc();
3310
3311 _verifier->check_bitmaps("GC Start");
3312
3313 #if defined(COMPILER2) || INCLUDE_JVMCI
3314 DerivedPointerTable::clear();
3315 #endif
3316
3317 // Please see comment in g1CollectedHeap.hpp and
3318 // G1CollectedHeap::ref_processing_init() to see how
3319 // reference processing currently works in G1.
3320
3321 // Enable discovery in the STW reference processor
3322 if (g1_policy()->should_process_references()) {
3323 ref_processor_stw()->enable_discovery();
3324 } else {
3325 ref_processor_stw()->disable_discovery();
3326 }
3327
3328 {
3329 // We want to temporarily turn off discovery by the
3330 // CM ref processor, if necessary, and turn it back on
3331 // on again later if we do. Using a scoped
3332 // NoRefDiscovery object will do this.
3333 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3334
3335 // Forget the current alloc region (we might even choose it to be part
3336 // of the collection set!).
3337 _allocator->release_mutator_alloc_region();
3338
3339 // This timing is only used by the ergonomics to handle our pause target.
3340 // It is unclear why this should not include the full pause. We will
3341 // investigate this in CR 7178365.
3342 //
3343 // Preserving the old comment here if that helps the investigation:
3344 //
3345 // The elapsed time induced by the start time below deliberately elides
3346 // the possible verification above.
3347 double sample_start_time_sec = os::elapsedTime();
3348
3349 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3350
3351 if (collector_state()->during_initial_mark_pause()) {
3352 concurrent_mark()->checkpointRootsInitialPre();
3353 }
3354
3355 g1_policy()->finalize_collection_set(target_pause_time_ms);
3356
3357 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3358
3359 // Make sure the remembered sets are up to date. This needs to be
3360 // done before register_humongous_regions_with_cset(), because the
3361 // remembered sets are used there to choose eager reclaim candidates.
3362 // If the remembered sets are not up to date we might miss some
3363 // entries that need to be handled.
3364 g1_rem_set()->cleanupHRRS();
3365
3366 register_humongous_regions_with_cset();
3367
3368 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3369
3370 _cm->note_start_of_gc();
3371 // We call this after finalize_cset() to
3372 // ensure that the CSet has been finalized.
3373 _cm->verify_no_cset_oops();
3374
3375 if (_hr_printer.is_active()) {
3376 HeapRegion* hr = collection_set()->head();
3377 while (hr != NULL) {
3378 _hr_printer.cset(hr);
3379 hr = hr->next_in_collection_set();
3380 }
3381 }
3382
3383 #ifdef ASSERT
3384 VerifyCSetClosure cl;
3385 collection_set_iterate(&cl);
3386 #endif // ASSERT
3387
3388 // Initialize the GC alloc regions.
3389 _allocator->init_gc_alloc_regions(evacuation_info);
3390
3391 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3392 pre_evacuate_collection_set();
3393
3394 // Actually do the work...
3395 evacuate_collection_set(evacuation_info, &per_thread_states);
3396
3397 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3398
3399 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3400 free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3401
3402 eagerly_reclaim_humongous_regions();
3403
3404 collection_set()->clear_head();
3405
3406 record_obj_copy_mem_stats();
3407 _survivor_evac_stats.adjust_desired_plab_sz();
3408 _old_evac_stats.adjust_desired_plab_sz();
3409
3410 // Start a new incremental collection set for the next pause.
3411 collection_set()->start_incremental_building();
3412
3413 clear_cset_fast_test();
3414
3415 // Don't check the whole heap at this point as the
3416 // GC alloc regions from this pause have been tagged
3417 // as survivors and moved on to the survivor list.
3418 // Survivor regions will fail the !is_young() check.
3419 assert(check_young_list_empty(false /* check_heap */),
3420 "young list should be empty");
3421
3422 _young_list->reset_auxilary_lists();
3423
3424 if (evacuation_failed()) {
3425 set_used(recalculate_used());
3426 if (_archive_allocator != NULL) {
3427 _archive_allocator->clear_used();
3428 }
3429 for (uint i = 0; i < ParallelGCThreads; i++) {
3430 if (_evacuation_failed_info_array[i].has_failed()) {
3431 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3432 }
3433 }
3434 } else {
3435 // The "used" of the the collection set have already been subtracted
3436 // when they were freed. Add in the bytes evacuated.
3437 increase_used(g1_policy()->bytes_copied_during_gc());
3438 }
3439
3440 if (collector_state()->during_initial_mark_pause()) {
3441 // We have to do this before we notify the CM threads that
3442 // they can start working to make sure that all the
3443 // appropriate initialization is done on the CM object.
3444 concurrent_mark()->checkpointRootsInitialPost();
3445 collector_state()->set_mark_in_progress(true);
3446 // Note that we don't actually trigger the CM thread at
3447 // this point. We do that later when we're sure that
3448 // the current thread has completed its logging output.
3449 }
3450
3451 allocate_dummy_regions();
3452
3453 _allocator->init_mutator_alloc_region();
3454
3455 {
3456 size_t expand_bytes = g1_policy()->expansion_amount();
3457 if (expand_bytes > 0) {
3458 size_t bytes_before = capacity();
3459 // No need for an ergo logging here,
3460 // expansion_amount() does this when it returns a value > 0.
3461 double expand_ms;
3462 if (!expand(expand_bytes, &expand_ms)) {
3463 // We failed to expand the heap. Cannot do anything about it.
3464 }
3465 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3466 }
3467 }
3468
3469 // We redo the verification but now wrt to the new CSet which
3470 // has just got initialized after the previous CSet was freed.
3471 _cm->verify_no_cset_oops();
3472 _cm->note_end_of_gc();
3473
3474 // This timing is only used by the ergonomics to handle our pause target.
3475 // It is unclear why this should not include the full pause. We will
3476 // investigate this in CR 7178365.
3477 double sample_end_time_sec = os::elapsedTime();
3478 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3479 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3480 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3481
3482 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3483 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3484
3485 MemoryService::track_memory_usage();
3486
3487 // In prepare_for_verify() below we'll need to scan the deferred
3488 // update buffers to bring the RSets up-to-date if
3489 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3490 // the update buffers we'll probably need to scan cards on the
3491 // regions we just allocated to (i.e., the GC alloc
3492 // regions). However, during the last GC we called
3493 // set_saved_mark() on all the GC alloc regions, so card
3494 // scanning might skip the [saved_mark_word()...top()] area of
3495 // those regions (i.e., the area we allocated objects into
3496 // during the last GC). But it shouldn't. Given that
3497 // saved_mark_word() is conditional on whether the GC time stamp
3498 // on the region is current or not, by incrementing the GC time
3499 // stamp here we invalidate all the GC time stamps on all the
3500 // regions and saved_mark_word() will simply return top() for
3501 // all the regions. This is a nicer way of ensuring this rather
3502 // than iterating over the regions and fixing them. In fact, the
3503 // GC time stamp increment here also ensures that
3504 // saved_mark_word() will return top() between pauses, i.e.,
3505 // during concurrent refinement. So we don't need the
3506 // is_gc_active() check to decided which top to use when
3507 // scanning cards (see CR 7039627).
3508 increment_gc_time_stamp();
3509
3510 if (VerifyRememberedSets) {
3511 log_info(gc, verify)("[Verifying RemSets after GC]");
3512 VerifyRegionRemSetClosure v_cl;
3513 heap_region_iterate(&v_cl);
3514 }
3515
3516 _verifier->verify_after_gc();
3517 _verifier->check_bitmaps("GC End");
3518
3519 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3520 ref_processor_stw()->verify_no_references_recorded();
3521
3522 // CM reference discovery will be re-enabled if necessary.
3523 }
3524
3525 #ifdef TRACESPINNING
3526 ParallelTaskTerminator::print_termination_counts();
3527 #endif
3528
3529 gc_epilogue(false);
3530 }
3531
3532 // Print the remainder of the GC log output.
3533 if (evacuation_failed()) {
3534 log_info(gc)("To-space exhausted");
3535 }
3536
3537 g1_policy()->print_phases();
3538 heap_transition.print();
3539
3540 // It is not yet to safe to tell the concurrent mark to
3541 // start as we have some optional output below. We don't want the
3542 // output from the concurrent mark thread interfering with this
3543 // logging output either.
3544
3545 _hrm.verify_optional();
3546 _verifier->verify_region_sets_optional();
3547
3548 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3549 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3550
3551 print_heap_after_gc();
3552 print_heap_regions();
3553 trace_heap_after_gc(_gc_tracer_stw);
3554
3555 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3556 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3557 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3558 // before any GC notifications are raised.
3559 g1mm()->update_sizes();
3560
3561 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3562 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3563 _gc_timer_stw->register_gc_end();
3564 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3565 }
3566 // It should now be safe to tell the concurrent mark thread to start
3567 // without its logging output interfering with the logging output
3568 // that came from the pause.
3569
3570 if (should_start_conc_mark) {
3571 // CAUTION: after the doConcurrentMark() call below,
3572 // the concurrent marking thread(s) could be running
3573 // concurrently with us. Make sure that anything after
3574 // this point does not assume that we are the only GC thread
3575 // running. Note: of course, the actual marking work will
3576 // not start until the safepoint itself is released in
3577 // SuspendibleThreadSet::desynchronize().
3578 doConcurrentMark();
3579 }
3580
3581 return true;
3582 }
3583
3584 void G1CollectedHeap::restore_preserved_marks() {
3585 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3586 workers()->run_task(&rpm_task);
3587 }
3588
3589 void G1CollectedHeap::remove_self_forwarding_pointers() {
3590 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3591 workers()->run_task(&rsfp_task);
3592 }
3593
3594 void G1CollectedHeap::restore_after_evac_failure() {
3595 double remove_self_forwards_start = os::elapsedTime();
3596
3597 remove_self_forwarding_pointers();
3598 restore_preserved_marks();
3599
3600 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3601 }
3602
3603 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3604 if (!_evacuation_failed) {
3605 _evacuation_failed = true;
3606 }
3607
3608 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3609
3610 // We want to call the "for_promotion_failure" version only in the
3611 // case of a promotion failure.
3612 if (m->must_be_preserved_for_promotion_failure(obj)) {
3613 OopAndMarkOop elem(obj, m);
3614 _preserved_objs[worker_id].push(elem);
3615 }
3616 }
3617
3618 bool G1ParEvacuateFollowersClosure::offer_termination() {
3619 G1ParScanThreadState* const pss = par_scan_state();
3620 start_term_time();
3621 const bool res = terminator()->offer_termination();
3622 end_term_time();
3623 return res;
3624 }
3625
3626 void G1ParEvacuateFollowersClosure::do_void() {
3627 G1ParScanThreadState* const pss = par_scan_state();
3628 pss->trim_queue();
3629 do {
3630 pss->steal_and_trim_queue(queues());
3631 } while (!offer_termination());
3632 }
3633
3634 class G1ParTask : public AbstractGangTask {
3635 protected:
3636 G1CollectedHeap* _g1h;
3637 G1ParScanThreadStateSet* _pss;
3638 RefToScanQueueSet* _queues;
3639 G1RootProcessor* _root_processor;
3640 ParallelTaskTerminator _terminator;
3641 uint _n_workers;
3642
3643 public:
3644 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3645 : AbstractGangTask("G1 collection"),
3646 _g1h(g1h),
3647 _pss(per_thread_states),
3648 _queues(task_queues),
3649 _root_processor(root_processor),
3650 _terminator(n_workers, _queues),
3651 _n_workers(n_workers)
3652 {}
3653
3654 void work(uint worker_id) {
3655 if (worker_id >= _n_workers) return; // no work needed this round
3656
3657 double start_sec = os::elapsedTime();
3658 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3659
3660 {
3661 ResourceMark rm;
3662 HandleMark hm;
3663
3664 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3665
3666 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3667 pss->set_ref_processor(rp);
3668
3669 double start_strong_roots_sec = os::elapsedTime();
3670
3671 _root_processor->evacuate_roots(pss->closures(), worker_id);
3672
3673 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3674
3675 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3676 // treating the nmethods visited to act as roots for concurrent marking.
3677 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3678 // objects copied by the current evacuation.
3679 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3680 pss->closures()->weak_codeblobs(),
3681 worker_id);
3682
3683 _pss->add_cards_scanned(worker_id, cards_scanned);
3684
3685 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3686
3687 double term_sec = 0.0;
3688 size_t evac_term_attempts = 0;
3689 {
3690 double start = os::elapsedTime();
3691 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3692 evac.do_void();
3693
3694 evac_term_attempts = evac.term_attempts();
3695 term_sec = evac.term_time();
3696 double elapsed_sec = os::elapsedTime() - start;
3697 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3698 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3699 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3700 }
3701
3702 assert(pss->queue_is_empty(), "should be empty");
3703
3704 if (log_is_enabled(Debug, gc, task, stats)) {
3705 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3706 size_t lab_waste;
3707 size_t lab_undo_waste;
3708 pss->waste(lab_waste, lab_undo_waste);
3709 _g1h->print_termination_stats(worker_id,
3710 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3711 strong_roots_sec * 1000.0, /* strong roots time */
3712 term_sec * 1000.0, /* evac term time */
3713 evac_term_attempts, /* evac term attempts */
3714 lab_waste, /* alloc buffer waste */
3715 lab_undo_waste /* undo waste */
3716 );
3717 }
3718
3719 // Close the inner scope so that the ResourceMark and HandleMark
3720 // destructors are executed here and are included as part of the
3721 // "GC Worker Time".
3722 }
3723 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3724 }
3725 };
3726
3727 void G1CollectedHeap::print_termination_stats_hdr() {
3728 log_debug(gc, task, stats)("GC Termination Stats");
3729 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3730 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3731 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3732 }
3733
3734 void G1CollectedHeap::print_termination_stats(uint worker_id,
3735 double elapsed_ms,
3736 double strong_roots_ms,
3737 double term_ms,
3738 size_t term_attempts,
3739 size_t alloc_buffer_waste,
3740 size_t undo_waste) const {
3741 log_debug(gc, task, stats)
3742 ("%3d %9.2f %9.2f %6.2f "
3743 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3744 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3745 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3746 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3747 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3748 alloc_buffer_waste * HeapWordSize / K,
3749 undo_waste * HeapWordSize / K);
3750 }
3751
3752 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3753 private:
3754 BoolObjectClosure* _is_alive;
3755 int _initial_string_table_size;
3756 int _initial_symbol_table_size;
3757
3758 bool _process_strings;
3759 int _strings_processed;
3760 int _strings_removed;
3761
3762 bool _process_symbols;
3763 int _symbols_processed;
3764 int _symbols_removed;
3765
3766 public:
3767 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3768 AbstractGangTask("String/Symbol Unlinking"),
3769 _is_alive(is_alive),
3770 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3771 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3772
3773 _initial_string_table_size = StringTable::the_table()->table_size();
3774 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3775 if (process_strings) {
3776 StringTable::clear_parallel_claimed_index();
3777 }
3778 if (process_symbols) {
3779 SymbolTable::clear_parallel_claimed_index();
3780 }
3781 }
3782
3783 ~G1StringSymbolTableUnlinkTask() {
3784 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3785 "claim value %d after unlink less than initial string table size %d",
3786 StringTable::parallel_claimed_index(), _initial_string_table_size);
3787 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3788 "claim value %d after unlink less than initial symbol table size %d",
3789 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3790
3791 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3792 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3793 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3794 strings_processed(), strings_removed(),
3795 symbols_processed(), symbols_removed());
3796 }
3797
3798 void work(uint worker_id) {
3799 int strings_processed = 0;
3800 int strings_removed = 0;
3801 int symbols_processed = 0;
3802 int symbols_removed = 0;
3803 if (_process_strings) {
3804 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3805 Atomic::add(strings_processed, &_strings_processed);
3806 Atomic::add(strings_removed, &_strings_removed);
3807 }
3808 if (_process_symbols) {
3809 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3810 Atomic::add(symbols_processed, &_symbols_processed);
3811 Atomic::add(symbols_removed, &_symbols_removed);
3812 }
3813 }
3814
3815 size_t strings_processed() const { return (size_t)_strings_processed; }
3816 size_t strings_removed() const { return (size_t)_strings_removed; }
3817
3818 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3819 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3820 };
3821
3822 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3823 private:
3824 static Monitor* _lock;
3825
3826 BoolObjectClosure* const _is_alive;
3827 const bool _unloading_occurred;
3828 const uint _num_workers;
3829
3830 // Variables used to claim nmethods.
3831 nmethod* _first_nmethod;
3832 volatile nmethod* _claimed_nmethod;
3833
3834 // The list of nmethods that need to be processed by the second pass.
3835 volatile nmethod* _postponed_list;
3836 volatile uint _num_entered_barrier;
3837
3838 public:
3839 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3840 _is_alive(is_alive),
3841 _unloading_occurred(unloading_occurred),
3842 _num_workers(num_workers),
3843 _first_nmethod(NULL),
3844 _claimed_nmethod(NULL),
3845 _postponed_list(NULL),
3846 _num_entered_barrier(0)
3847 {
3848 nmethod::increase_unloading_clock();
3849 // Get first alive nmethod
3850 NMethodIterator iter = NMethodIterator();
3851 if(iter.next_alive()) {
3852 _first_nmethod = iter.method();
3853 }
3854 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3855 }
3856
3857 ~G1CodeCacheUnloadingTask() {
3858 CodeCache::verify_clean_inline_caches();
3859
3860 CodeCache::set_needs_cache_clean(false);
3861 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3862
3863 CodeCache::verify_icholder_relocations();
3864 }
3865
3866 private:
3867 void add_to_postponed_list(nmethod* nm) {
3868 nmethod* old;
3869 do {
3870 old = (nmethod*)_postponed_list;
3871 nm->set_unloading_next(old);
3872 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3873 }
3874
3875 void clean_nmethod(nmethod* nm) {
3876 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3877
3878 if (postponed) {
3879 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3880 add_to_postponed_list(nm);
3881 }
3882
3883 // Mark that this thread has been cleaned/unloaded.
3884 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3885 nm->set_unloading_clock(nmethod::global_unloading_clock());
3886 }
3887
3888 void clean_nmethod_postponed(nmethod* nm) {
3889 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3890 }
3891
3892 static const int MaxClaimNmethods = 16;
3893
3894 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3895 nmethod* first;
3896 NMethodIterator last;
3897
3898 do {
3899 *num_claimed_nmethods = 0;
3900
3901 first = (nmethod*)_claimed_nmethod;
3902 last = NMethodIterator(first);
3903
3904 if (first != NULL) {
3905
3906 for (int i = 0; i < MaxClaimNmethods; i++) {
3907 if (!last.next_alive()) {
3908 break;
3909 }
3910 claimed_nmethods[i] = last.method();
3911 (*num_claimed_nmethods)++;
3912 }
3913 }
3914
3915 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3916 }
3917
3918 nmethod* claim_postponed_nmethod() {
3919 nmethod* claim;
3920 nmethod* next;
3921
3922 do {
3923 claim = (nmethod*)_postponed_list;
3924 if (claim == NULL) {
3925 return NULL;
3926 }
3927
3928 next = claim->unloading_next();
3929
3930 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3931
3932 return claim;
3933 }
3934
3935 public:
3936 // Mark that we're done with the first pass of nmethod cleaning.
3937 void barrier_mark(uint worker_id) {
3938 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3939 _num_entered_barrier++;
3940 if (_num_entered_barrier == _num_workers) {
3941 ml.notify_all();
3942 }
3943 }
3944
3945 // See if we have to wait for the other workers to
3946 // finish their first-pass nmethod cleaning work.
3947 void barrier_wait(uint worker_id) {
3948 if (_num_entered_barrier < _num_workers) {
3949 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3950 while (_num_entered_barrier < _num_workers) {
3951 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3952 }
3953 }
3954 }
3955
3956 // Cleaning and unloading of nmethods. Some work has to be postponed
3957 // to the second pass, when we know which nmethods survive.
3958 void work_first_pass(uint worker_id) {
3959 // The first nmethods is claimed by the first worker.
3960 if (worker_id == 0 && _first_nmethod != NULL) {
3961 clean_nmethod(_first_nmethod);
3962 _first_nmethod = NULL;
3963 }
3964
3965 int num_claimed_nmethods;
3966 nmethod* claimed_nmethods[MaxClaimNmethods];
3967
3968 while (true) {
3969 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3970
3971 if (num_claimed_nmethods == 0) {
3972 break;
3973 }
3974
3975 for (int i = 0; i < num_claimed_nmethods; i++) {
3976 clean_nmethod(claimed_nmethods[i]);
3977 }
3978 }
3979 }
3980
3981 void work_second_pass(uint worker_id) {
3982 nmethod* nm;
3983 // Take care of postponed nmethods.
3984 while ((nm = claim_postponed_nmethod()) != NULL) {
3985 clean_nmethod_postponed(nm);
3986 }
3987 }
3988 };
3989
3990 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3991
3992 class G1KlassCleaningTask : public StackObj {
3993 BoolObjectClosure* _is_alive;
3994 volatile jint _clean_klass_tree_claimed;
3995 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3996
3997 public:
3998 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3999 _is_alive(is_alive),
4000 _clean_klass_tree_claimed(0),
4001 _klass_iterator() {
4002 }
4003
4004 private:
4005 bool claim_clean_klass_tree_task() {
4006 if (_clean_klass_tree_claimed) {
4007 return false;
4008 }
4009
4010 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4011 }
4012
4013 InstanceKlass* claim_next_klass() {
4014 Klass* klass;
4015 do {
4016 klass =_klass_iterator.next_klass();
4017 } while (klass != NULL && !klass->is_instance_klass());
4018
4019 // this can be null so don't call InstanceKlass::cast
4020 return static_cast<InstanceKlass*>(klass);
4021 }
4022
4023 public:
4024
4025 void clean_klass(InstanceKlass* ik) {
4026 ik->clean_weak_instanceklass_links(_is_alive);
4027 }
4028
4029 void work() {
4030 ResourceMark rm;
4031
4032 // One worker will clean the subklass/sibling klass tree.
4033 if (claim_clean_klass_tree_task()) {
4034 Klass::clean_subklass_tree(_is_alive);
4035 }
4036
4037 // All workers will help cleaning the classes,
4038 InstanceKlass* klass;
4039 while ((klass = claim_next_klass()) != NULL) {
4040 clean_klass(klass);
4041 }
4042 }
4043 };
4044
4045 // To minimize the remark pause times, the tasks below are done in parallel.
4046 class G1ParallelCleaningTask : public AbstractGangTask {
4047 private:
4048 G1StringSymbolTableUnlinkTask _string_symbol_task;
4049 G1CodeCacheUnloadingTask _code_cache_task;
4050 G1KlassCleaningTask _klass_cleaning_task;
4051
4052 public:
4053 // The constructor is run in the VMThread.
4054 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4055 AbstractGangTask("Parallel Cleaning"),
4056 _string_symbol_task(is_alive, process_strings, process_symbols),
4057 _code_cache_task(num_workers, is_alive, unloading_occurred),
4058 _klass_cleaning_task(is_alive) {
4059 }
4060
4061 // The parallel work done by all worker threads.
4062 void work(uint worker_id) {
4063 // Do first pass of code cache cleaning.
4064 _code_cache_task.work_first_pass(worker_id);
4065
4066 // Let the threads mark that the first pass is done.
4067 _code_cache_task.barrier_mark(worker_id);
4068
4069 // Clean the Strings and Symbols.
4070 _string_symbol_task.work(worker_id);
4071
4072 // Wait for all workers to finish the first code cache cleaning pass.
4073 _code_cache_task.barrier_wait(worker_id);
4074
4075 // Do the second code cache cleaning work, which realize on
4076 // the liveness information gathered during the first pass.
4077 _code_cache_task.work_second_pass(worker_id);
4078
4079 // Clean all klasses that were not unloaded.
4080 _klass_cleaning_task.work();
4081 }
4082 };
4083
4084
4085 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4086 bool process_strings,
4087 bool process_symbols,
4088 bool class_unloading_occurred) {
4089 uint n_workers = workers()->active_workers();
4090
4091 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4092 n_workers, class_unloading_occurred);
4093 workers()->run_task(&g1_unlink_task);
4094 }
4095
4096 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4097 bool process_strings, bool process_symbols) {
4098 {
4099 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4100 workers()->run_task(&g1_unlink_task);
4101 }
4102
4103 if (G1StringDedup::is_enabled()) {
4104 G1StringDedup::unlink(is_alive);
4105 }
4106 }
4107
4108 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4109 private:
4110 DirtyCardQueueSet* _queue;
4111 G1CollectedHeap* _g1h;
4112 public:
4113 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4114 _queue(queue), _g1h(g1h) { }
4115
4116 virtual void work(uint worker_id) {
4117 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4118 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4119
4120 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4121 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4122
4123 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4124 }
4125 };
4126
4127 void G1CollectedHeap::redirty_logged_cards() {
4128 double redirty_logged_cards_start = os::elapsedTime();
4129
4130 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4131 dirty_card_queue_set().reset_for_par_iteration();
4132 workers()->run_task(&redirty_task);
4133
4134 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4135 dcq.merge_bufferlists(&dirty_card_queue_set());
4136 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4137
4138 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4139 }
4140
4141 // Weak Reference Processing support
4142
4143 // An always "is_alive" closure that is used to preserve referents.
4144 // If the object is non-null then it's alive. Used in the preservation
4145 // of referent objects that are pointed to by reference objects
4146 // discovered by the CM ref processor.
4147 class G1AlwaysAliveClosure: public BoolObjectClosure {
4148 G1CollectedHeap* _g1;
4149 public:
4150 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4151 bool do_object_b(oop p) {
4152 if (p != NULL) {
4153 return true;
4154 }
4155 return false;
4156 }
4157 };
4158
4159 bool G1STWIsAliveClosure::do_object_b(oop p) {
4160 // An object is reachable if it is outside the collection set,
4161 // or is inside and copied.
4162 return !_g1->is_in_cset(p) || p->is_forwarded();
4163 }
4164
4165 // Non Copying Keep Alive closure
4166 class G1KeepAliveClosure: public OopClosure {
4167 G1CollectedHeap* _g1;
4168 public:
4169 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4170 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4171 void do_oop(oop* p) {
4172 oop obj = *p;
4173 assert(obj != NULL, "the caller should have filtered out NULL values");
4174
4175 const InCSetState cset_state = _g1->in_cset_state(obj);
4176 if (!cset_state.is_in_cset_or_humongous()) {
4177 return;
4178 }
4179 if (cset_state.is_in_cset()) {
4180 assert( obj->is_forwarded(), "invariant" );
4181 *p = obj->forwardee();
4182 } else {
4183 assert(!obj->is_forwarded(), "invariant" );
4184 assert(cset_state.is_humongous(),
4185 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4186 _g1->set_humongous_is_live(obj);
4187 }
4188 }
4189 };
4190
4191 // Copying Keep Alive closure - can be called from both
4192 // serial and parallel code as long as different worker
4193 // threads utilize different G1ParScanThreadState instances
4194 // and different queues.
4195
4196 class G1CopyingKeepAliveClosure: public OopClosure {
4197 G1CollectedHeap* _g1h;
4198 OopClosure* _copy_non_heap_obj_cl;
4199 G1ParScanThreadState* _par_scan_state;
4200
4201 public:
4202 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4203 OopClosure* non_heap_obj_cl,
4204 G1ParScanThreadState* pss):
4205 _g1h(g1h),
4206 _copy_non_heap_obj_cl(non_heap_obj_cl),
4207 _par_scan_state(pss)
4208 {}
4209
4210 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4211 virtual void do_oop( oop* p) { do_oop_work(p); }
4212
4213 template <class T> void do_oop_work(T* p) {
4214 oop obj = oopDesc::load_decode_heap_oop(p);
4215
4216 if (_g1h->is_in_cset_or_humongous(obj)) {
4217 // If the referent object has been forwarded (either copied
4218 // to a new location or to itself in the event of an
4219 // evacuation failure) then we need to update the reference
4220 // field and, if both reference and referent are in the G1
4221 // heap, update the RSet for the referent.
4222 //
4223 // If the referent has not been forwarded then we have to keep
4224 // it alive by policy. Therefore we have copy the referent.
4225 //
4226 // If the reference field is in the G1 heap then we can push
4227 // on the PSS queue. When the queue is drained (after each
4228 // phase of reference processing) the object and it's followers
4229 // will be copied, the reference field set to point to the
4230 // new location, and the RSet updated. Otherwise we need to
4231 // use the the non-heap or metadata closures directly to copy
4232 // the referent object and update the pointer, while avoiding
4233 // updating the RSet.
4234
4235 if (_g1h->is_in_g1_reserved(p)) {
4236 _par_scan_state->push_on_queue(p);
4237 } else {
4238 assert(!Metaspace::contains((const void*)p),
4239 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4240 _copy_non_heap_obj_cl->do_oop(p);
4241 }
4242 }
4243 }
4244 };
4245
4246 // Serial drain queue closure. Called as the 'complete_gc'
4247 // closure for each discovered list in some of the
4248 // reference processing phases.
4249
4250 class G1STWDrainQueueClosure: public VoidClosure {
4251 protected:
4252 G1CollectedHeap* _g1h;
4253 G1ParScanThreadState* _par_scan_state;
4254
4255 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4256
4257 public:
4258 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4259 _g1h(g1h),
4260 _par_scan_state(pss)
4261 { }
4262
4263 void do_void() {
4264 G1ParScanThreadState* const pss = par_scan_state();
4265 pss->trim_queue();
4266 }
4267 };
4268
4269 // Parallel Reference Processing closures
4270
4271 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4272 // processing during G1 evacuation pauses.
4273
4274 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4275 private:
4276 G1CollectedHeap* _g1h;
4277 G1ParScanThreadStateSet* _pss;
4278 RefToScanQueueSet* _queues;
4279 WorkGang* _workers;
4280 uint _active_workers;
4281
4282 public:
4283 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4284 G1ParScanThreadStateSet* per_thread_states,
4285 WorkGang* workers,
4286 RefToScanQueueSet *task_queues,
4287 uint n_workers) :
4288 _g1h(g1h),
4289 _pss(per_thread_states),
4290 _queues(task_queues),
4291 _workers(workers),
4292 _active_workers(n_workers)
4293 {
4294 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4295 }
4296
4297 // Executes the given task using concurrent marking worker threads.
4298 virtual void execute(ProcessTask& task);
4299 virtual void execute(EnqueueTask& task);
4300 };
4301
4302 // Gang task for possibly parallel reference processing
4303
4304 class G1STWRefProcTaskProxy: public AbstractGangTask {
4305 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4306 ProcessTask& _proc_task;
4307 G1CollectedHeap* _g1h;
4308 G1ParScanThreadStateSet* _pss;
4309 RefToScanQueueSet* _task_queues;
4310 ParallelTaskTerminator* _terminator;
4311
4312 public:
4313 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4314 G1CollectedHeap* g1h,
4315 G1ParScanThreadStateSet* per_thread_states,
4316 RefToScanQueueSet *task_queues,
4317 ParallelTaskTerminator* terminator) :
4318 AbstractGangTask("Process reference objects in parallel"),
4319 _proc_task(proc_task),
4320 _g1h(g1h),
4321 _pss(per_thread_states),
4322 _task_queues(task_queues),
4323 _terminator(terminator)
4324 {}
4325
4326 virtual void work(uint worker_id) {
4327 // The reference processing task executed by a single worker.
4328 ResourceMark rm;
4329 HandleMark hm;
4330
4331 G1STWIsAliveClosure is_alive(_g1h);
4332
4333 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4334 pss->set_ref_processor(NULL);
4335
4336 // Keep alive closure.
4337 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4338
4339 // Complete GC closure
4340 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4341
4342 // Call the reference processing task's work routine.
4343 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4344
4345 // Note we cannot assert that the refs array is empty here as not all
4346 // of the processing tasks (specifically phase2 - pp2_work) execute
4347 // the complete_gc closure (which ordinarily would drain the queue) so
4348 // the queue may not be empty.
4349 }
4350 };
4351
4352 // Driver routine for parallel reference processing.
4353 // Creates an instance of the ref processing gang
4354 // task and has the worker threads execute it.
4355 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4356 assert(_workers != NULL, "Need parallel worker threads.");
4357
4358 ParallelTaskTerminator terminator(_active_workers, _queues);
4359 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4360
4361 _workers->run_task(&proc_task_proxy);
4362 }
4363
4364 // Gang task for parallel reference enqueueing.
4365
4366 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4367 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4368 EnqueueTask& _enq_task;
4369
4370 public:
4371 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4372 AbstractGangTask("Enqueue reference objects in parallel"),
4373 _enq_task(enq_task)
4374 { }
4375
4376 virtual void work(uint worker_id) {
4377 _enq_task.work(worker_id);
4378 }
4379 };
4380
4381 // Driver routine for parallel reference enqueueing.
4382 // Creates an instance of the ref enqueueing gang
4383 // task and has the worker threads execute it.
4384
4385 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4386 assert(_workers != NULL, "Need parallel worker threads.");
4387
4388 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4389
4390 _workers->run_task(&enq_task_proxy);
4391 }
4392
4393 // End of weak reference support closures
4394
4395 // Abstract task used to preserve (i.e. copy) any referent objects
4396 // that are in the collection set and are pointed to by reference
4397 // objects discovered by the CM ref processor.
4398
4399 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4400 protected:
4401 G1CollectedHeap* _g1h;
4402 G1ParScanThreadStateSet* _pss;
4403 RefToScanQueueSet* _queues;
4404 ParallelTaskTerminator _terminator;
4405 uint _n_workers;
4406
4407 public:
4408 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4409 AbstractGangTask("ParPreserveCMReferents"),
4410 _g1h(g1h),
4411 _pss(per_thread_states),
4412 _queues(task_queues),
4413 _terminator(workers, _queues),
4414 _n_workers(workers)
4415 {
4416 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4417 }
4418
4419 void work(uint worker_id) {
4420 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4421
4422 ResourceMark rm;
4423 HandleMark hm;
4424
4425 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4426 pss->set_ref_processor(NULL);
4427 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4428
4429 // Is alive closure
4430 G1AlwaysAliveClosure always_alive(_g1h);
4431
4432 // Copying keep alive closure. Applied to referent objects that need
4433 // to be copied.
4434 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4435
4436 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4437
4438 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4439 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4440
4441 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4442 // So this must be true - but assert just in case someone decides to
4443 // change the worker ids.
4444 assert(worker_id < limit, "sanity");
4445 assert(!rp->discovery_is_atomic(), "check this code");
4446
4447 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4448 for (uint idx = worker_id; idx < limit; idx += stride) {
4449 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4450
4451 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4452 while (iter.has_next()) {
4453 // Since discovery is not atomic for the CM ref processor, we
4454 // can see some null referent objects.
4455 iter.load_ptrs(DEBUG_ONLY(true));
4456 oop ref = iter.obj();
4457
4458 // This will filter nulls.
4459 if (iter.is_referent_alive()) {
4460 iter.make_referent_alive();
4461 }
4462 iter.move_to_next();
4463 }
4464 }
4465
4466 // Drain the queue - which may cause stealing
4467 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4468 drain_queue.do_void();
4469 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4470 assert(pss->queue_is_empty(), "should be");
4471 }
4472 };
4473
4474 void G1CollectedHeap::process_weak_jni_handles() {
4475 double ref_proc_start = os::elapsedTime();
4476
4477 G1STWIsAliveClosure is_alive(this);
4478 G1KeepAliveClosure keep_alive(this);
4479 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4480
4481 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4482 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4483 }
4484
4485 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4486 double preserve_cm_referents_start = os::elapsedTime();
4487 // Any reference objects, in the collection set, that were 'discovered'
4488 // by the CM ref processor should have already been copied (either by
4489 // applying the external root copy closure to the discovered lists, or
4490 // by following an RSet entry).
4491 //
4492 // But some of the referents, that are in the collection set, that these
4493 // reference objects point to may not have been copied: the STW ref
4494 // processor would have seen that the reference object had already
4495 // been 'discovered' and would have skipped discovering the reference,
4496 // but would not have treated the reference object as a regular oop.
4497 // As a result the copy closure would not have been applied to the
4498 // referent object.
4499 //
4500 // We need to explicitly copy these referent objects - the references
4501 // will be processed at the end of remarking.
4502 //
4503 // We also need to do this copying before we process the reference
4504 // objects discovered by the STW ref processor in case one of these
4505 // referents points to another object which is also referenced by an
4506 // object discovered by the STW ref processor.
4507
4508 uint no_of_gc_workers = workers()->active_workers();
4509
4510 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4511 per_thread_states,
4512 no_of_gc_workers,
4513 _task_queues);
4514 workers()->run_task(&keep_cm_referents);
4515
4516 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4517 }
4518
4519 // Weak Reference processing during an evacuation pause (part 1).
4520 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4521 double ref_proc_start = os::elapsedTime();
4522
4523 ReferenceProcessor* rp = _ref_processor_stw;
4524 assert(rp->discovery_enabled(), "should have been enabled");
4525
4526 // Closure to test whether a referent is alive.
4527 G1STWIsAliveClosure is_alive(this);
4528
4529 // Even when parallel reference processing is enabled, the processing
4530 // of JNI refs is serial and performed serially by the current thread
4531 // rather than by a worker. The following PSS will be used for processing
4532 // JNI refs.
4533
4534 // Use only a single queue for this PSS.
4535 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4536 pss->set_ref_processor(NULL);
4537 assert(pss->queue_is_empty(), "pre-condition");
4538
4539 // Keep alive closure.
4540 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4541
4542 // Serial Complete GC closure
4543 G1STWDrainQueueClosure drain_queue(this, pss);
4544
4545 // Setup the soft refs policy...
4546 rp->setup_policy(false);
4547
4548 ReferenceProcessorStats stats;
4549 if (!rp->processing_is_mt()) {
4550 // Serial reference processing...
4551 stats = rp->process_discovered_references(&is_alive,
4552 &keep_alive,
4553 &drain_queue,
4554 NULL,
4555 _gc_timer_stw);
4556 } else {
4557 uint no_of_gc_workers = workers()->active_workers();
4558
4559 // Parallel reference processing
4560 assert(no_of_gc_workers <= rp->max_num_q(),
4561 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4562 no_of_gc_workers, rp->max_num_q());
4563
4564 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4565 stats = rp->process_discovered_references(&is_alive,
4566 &keep_alive,
4567 &drain_queue,
4568 &par_task_executor,
4569 _gc_timer_stw);
4570 }
4571
4572 _gc_tracer_stw->report_gc_reference_stats(stats);
4573
4574 // We have completed copying any necessary live referent objects.
4575 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4576
4577 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4578 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4579 }
4580
4581 // Weak Reference processing during an evacuation pause (part 2).
4582 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4583 double ref_enq_start = os::elapsedTime();
4584
4585 ReferenceProcessor* rp = _ref_processor_stw;
4586 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4587
4588 // Now enqueue any remaining on the discovered lists on to
4589 // the pending list.
4590 if (!rp->processing_is_mt()) {
4591 // Serial reference processing...
4592 rp->enqueue_discovered_references();
4593 } else {
4594 // Parallel reference enqueueing
4595
4596 uint n_workers = workers()->active_workers();
4597
4598 assert(n_workers <= rp->max_num_q(),
4599 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4600 n_workers, rp->max_num_q());
4601
4602 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4603 rp->enqueue_discovered_references(&par_task_executor);
4604 }
4605
4606 rp->verify_no_references_recorded();
4607 assert(!rp->discovery_enabled(), "should have been disabled");
4608
4609 // FIXME
4610 // CM's reference processing also cleans up the string and symbol tables.
4611 // Should we do that here also? We could, but it is a serial operation
4612 // and could significantly increase the pause time.
4613
4614 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4615 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4616 }
4617
4618 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4619 double merge_pss_time_start = os::elapsedTime();
4620 per_thread_states->flush();
4621 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4622 }
4623
4624 void G1CollectedHeap::pre_evacuate_collection_set() {
4625 _expand_heap_after_alloc_failure = true;
4626 _evacuation_failed = false;
4627
4628 // Disable the hot card cache.
4629 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4630 hot_card_cache->reset_hot_cache_claimed_index();
4631 hot_card_cache->set_use_cache(false);
4632
4633 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4634 }
4635
4636 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4637 // Should G1EvacuationFailureALot be in effect for this GC?
4638 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4639
4640 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4641 double start_par_time_sec = os::elapsedTime();
4642 double end_par_time_sec;
4643
4644 {
4645 const uint n_workers = workers()->active_workers();
4646 G1RootProcessor root_processor(this, n_workers);
4647 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4648 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4649 if (collector_state()->during_initial_mark_pause()) {
4650 ClassLoaderDataGraph::clear_claimed_marks();
4651 }
4652
4653 print_termination_stats_hdr();
4654
4655 workers()->run_task(&g1_par_task);
4656 end_par_time_sec = os::elapsedTime();
4657
4658 // Closing the inner scope will execute the destructor
4659 // for the G1RootProcessor object. We record the current
4660 // elapsed time before closing the scope so that time
4661 // taken for the destructor is NOT included in the
4662 // reported parallel time.
4663 }
4664
4665 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4666
4667 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4668 phase_times->record_par_time(par_time_ms);
4669
4670 double code_root_fixup_time_ms =
4671 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4672 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4673 }
4674
4675 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4676 // Process any discovered reference objects - we have
4677 // to do this _before_ we retire the GC alloc regions
4678 // as we may have to copy some 'reachable' referent
4679 // objects (and their reachable sub-graphs) that were
4680 // not copied during the pause.
4681 if (g1_policy()->should_process_references()) {
4682 preserve_cm_referents(per_thread_states);
4683 process_discovered_references(per_thread_states);
4684 } else {
4685 ref_processor_stw()->verify_no_references_recorded();
4686 process_weak_jni_handles();
4687 }
4688
4689 if (G1StringDedup::is_enabled()) {
4690 double fixup_start = os::elapsedTime();
4691
4692 G1STWIsAliveClosure is_alive(this);
4693 G1KeepAliveClosure keep_alive(this);
4694 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4695
4696 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4697 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4698 }
4699
4700 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4701
4702 if (evacuation_failed()) {
4703 restore_after_evac_failure();
4704
4705 // Reset the G1EvacuationFailureALot counters and flags
4706 // Note: the values are reset only when an actual
4707 // evacuation failure occurs.
4708 NOT_PRODUCT(reset_evacuation_should_fail();)
4709 }
4710
4711 // Enqueue any remaining references remaining on the STW
4712 // reference processor's discovered lists. We need to do
4713 // this after the card table is cleaned (and verified) as
4714 // the act of enqueueing entries on to the pending list
4715 // will log these updates (and dirty their associated
4716 // cards). We need these updates logged to update any
4717 // RSets.
4718 if (g1_policy()->should_process_references()) {
4719 enqueue_discovered_references(per_thread_states);
4720 } else {
4721 g1_policy()->phase_times()->record_ref_enq_time(0);
4722 }
4723
4724 _allocator->release_gc_alloc_regions(evacuation_info);
4725
4726 merge_per_thread_state_info(per_thread_states);
4727
4728 // Reset and re-enable the hot card cache.
4729 // Note the counts for the cards in the regions in the
4730 // collection set are reset when the collection set is freed.
4731 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4732 hot_card_cache->reset_hot_cache();
4733 hot_card_cache->set_use_cache(true);
4734
4735 purge_code_root_memory();
4736
4737 redirty_logged_cards();
4738 #if defined(COMPILER2) || INCLUDE_JVMCI
4739 DerivedPointerTable::update_pointers();
4740 #endif
4741 }
4742
4743 void G1CollectedHeap::record_obj_copy_mem_stats() {
4744 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4745
4746 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4747 create_g1_evac_summary(&_old_evac_stats));
4748 }
4749
4750 void G1CollectedHeap::free_region(HeapRegion* hr,
4751 FreeRegionList* free_list,
4752 bool par,
4753 bool locked) {
4754 assert(!hr->is_free(), "the region should not be free");
4755 assert(!hr->is_empty(), "the region should not be empty");
4756 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4757 assert(free_list != NULL, "pre-condition");
4758
4759 if (G1VerifyBitmaps) {
4760 MemRegion mr(hr->bottom(), hr->end());
4761 concurrent_mark()->clearRangePrevBitmap(mr);
4762 }
4763
4764 // Clear the card counts for this region.
4765 // Note: we only need to do this if the region is not young
4766 // (since we don't refine cards in young regions).
4767 if (!hr->is_young()) {
4768 _cg1r->hot_card_cache()->reset_card_counts(hr);
4769 }
4770 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4771 free_list->add_ordered(hr);
4772 }
4773
4774 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4775 FreeRegionList* free_list,
4776 bool par) {
4777 assert(hr->is_humongous(), "this is only for humongous regions");
4778 assert(free_list != NULL, "pre-condition");
4779 hr->clear_humongous();
4780 free_region(hr, free_list, par);
4781 }
4782
4783 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4784 const uint humongous_regions_removed) {
4785 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4786 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4787 _old_set.bulk_remove(old_regions_removed);
4788 _humongous_set.bulk_remove(humongous_regions_removed);
4789 }
4790
4791 }
4792
4793 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4794 assert(list != NULL, "list can't be null");
4795 if (!list->is_empty()) {
4796 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4797 _hrm.insert_list_into_free_list(list);
4798 }
4799 }
4800
4801 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4802 decrease_used(bytes);
4803 }
4804
4805 class G1ParCleanupCTTask : public AbstractGangTask {
4806 G1SATBCardTableModRefBS* _ct_bs;
4807 G1CollectedHeap* _g1h;
4808 HeapRegion* volatile _su_head;
4809 public:
4810 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4811 G1CollectedHeap* g1h) :
4812 AbstractGangTask("G1 Par Cleanup CT Task"),
4813 _ct_bs(ct_bs), _g1h(g1h) { }
4814
4815 void work(uint worker_id) {
4816 HeapRegion* r;
4817 while (r = _g1h->pop_dirty_cards_region()) {
4818 clear_cards(r);
4819 }
4820 }
4821
4822 void clear_cards(HeapRegion* r) {
4823 // Cards of the survivors should have already been dirtied.
4824 if (!r->is_survivor()) {
4825 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4826 }
4827 }
4828 };
4829
4830 class G1ParScrubRemSetTask: public AbstractGangTask {
4831 protected:
4832 G1RemSet* _g1rs;
4833 BitMap* _region_bm;
4834 BitMap* _card_bm;
4835 HeapRegionClaimer _hrclaimer;
4836
4837 public:
4838 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4839 AbstractGangTask("G1 ScrubRS"),
4840 _g1rs(g1_rs),
4841 _region_bm(region_bm),
4842 _card_bm(card_bm),
4843 _hrclaimer(num_workers) {
4844 }
4845
4846 void work(uint worker_id) {
4847 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4848 }
4849 };
4850
4851 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4852 uint num_workers = workers()->active_workers();
4853 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4854 workers()->run_task(&g1_par_scrub_rs_task);
4855 }
4856
4857 void G1CollectedHeap::cleanUpCardTable() {
4858 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4859 double start = os::elapsedTime();
4860
4861 {
4862 // Iterate over the dirty cards region list.
4863 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4864
4865 workers()->run_task(&cleanup_task);
4866 #ifndef PRODUCT
4867 _verifier->verify_card_table_cleanup();
4868 #endif
4869 }
4870
4871 double elapsed = os::elapsedTime() - start;
4872 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4873 }
4874
4875 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4876 size_t pre_used = 0;
4877 FreeRegionList local_free_list("Local List for CSet Freeing");
4878
4879 double young_time_ms = 0.0;
4880 double non_young_time_ms = 0.0;
4881
4882 // Since the collection set is a superset of the the young list,
4883 // all we need to do to clear the young list is clear its
4884 // head and length, and unlink any young regions in the code below
4885 _young_list->clear();
4886
4887 G1CollectorPolicy* policy = g1_policy();
4888
4889 double start_sec = os::elapsedTime();
4890 bool non_young = true;
4891
4892 HeapRegion* cur = cs_head;
4893 int age_bound = -1;
4894 size_t rs_lengths = 0;
4895
4896 while (cur != NULL) {
4897 assert(!is_on_master_free_list(cur), "sanity");
4898 if (non_young) {
4899 if (cur->is_young()) {
4900 double end_sec = os::elapsedTime();
4901 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4902 non_young_time_ms += elapsed_ms;
4903
4904 start_sec = os::elapsedTime();
4905 non_young = false;
4906 }
4907 } else {
4908 if (!cur->is_young()) {
4909 double end_sec = os::elapsedTime();
4910 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4911 young_time_ms += elapsed_ms;
4912
4913 start_sec = os::elapsedTime();
4914 non_young = true;
4915 }
4916 }
4917
4918 rs_lengths += cur->rem_set()->occupied_locked();
4919
4920 HeapRegion* next = cur->next_in_collection_set();
4921 assert(cur->in_collection_set(), "bad CS");
4922 cur->set_next_in_collection_set(NULL);
4923 clear_in_cset(cur);
4924
4925 if (cur->is_young()) {
4926 int index = cur->young_index_in_cset();
4927 assert(index != -1, "invariant");
4928 assert((uint) index < collection_set()->young_region_length(), "invariant");
4929 size_t words_survived = surviving_young_words[index];
4930 cur->record_surv_words_in_group(words_survived);
4931
4932 // At this point the we have 'popped' cur from the collection set
4933 // (linked via next_in_collection_set()) but it is still in the
4934 // young list (linked via next_young_region()). Clear the
4935 // _next_young_region field.
4936 cur->set_next_young_region(NULL);
4937 } else {
4938 int index = cur->young_index_in_cset();
4939 assert(index == -1, "invariant");
4940 }
4941
4942 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4943 (!cur->is_young() && cur->young_index_in_cset() == -1),
4944 "invariant" );
4945
4946 if (!cur->evacuation_failed()) {
4947 MemRegion used_mr = cur->used_region();
4948
4949 // And the region is empty.
4950 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4951 pre_used += cur->used();
4952 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4953 } else {
4954 cur->uninstall_surv_rate_group();
4955 if (cur->is_young()) {
4956 cur->set_young_index_in_cset(-1);
4957 }
4958 cur->set_evacuation_failed(false);
4959 // When moving a young gen region to old gen, we "allocate" that whole region
4960 // there. This is in addition to any already evacuated objects. Notify the
4961 // policy about that.
4962 // Old gen regions do not cause an additional allocation: both the objects
4963 // still in the region and the ones already moved are accounted for elsewhere.
4964 if (cur->is_young()) {
4965 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4966 }
4967 // The region is now considered to be old.
4968 cur->set_old();
4969 // Do some allocation statistics accounting. Regions that failed evacuation
4970 // are always made old, so there is no need to update anything in the young
4971 // gen statistics, but we need to update old gen statistics.
4972 size_t used_words = cur->marked_bytes() / HeapWordSize;
4973 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4974 _old_set.add(cur);
4975 evacuation_info.increment_collectionset_used_after(cur->used());
4976 }
4977 cur = next;
4978 }
4979
4980 evacuation_info.set_regions_freed(local_free_list.length());
4981 policy->record_max_rs_lengths(rs_lengths);
4982 policy->cset_regions_freed();
4983
4984 double end_sec = os::elapsedTime();
4985 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4986
4987 if (non_young) {
4988 non_young_time_ms += elapsed_ms;
4989 } else {
4990 young_time_ms += elapsed_ms;
4991 }
4992
4993 prepend_to_freelist(&local_free_list);
4994 decrement_summary_bytes(pre_used);
4995 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4996 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4997 }
4998
4999 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5000 private:
5001 FreeRegionList* _free_region_list;
5002 HeapRegionSet* _proxy_set;
5003 uint _humongous_regions_removed;
5004 size_t _freed_bytes;
5005 public:
5006
5007 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5008 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5009 }
5010
5011 virtual bool doHeapRegion(HeapRegion* r) {
5012 if (!r->is_starts_humongous()) {
5013 return false;
5014 }
5015
5016 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5017
5018 oop obj = (oop)r->bottom();
5019 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5020
5021 // The following checks whether the humongous object is live are sufficient.
5022 // The main additional check (in addition to having a reference from the roots
5023 // or the young gen) is whether the humongous object has a remembered set entry.
5024 //
5025 // A humongous object cannot be live if there is no remembered set for it
5026 // because:
5027 // - there can be no references from within humongous starts regions referencing
5028 // the object because we never allocate other objects into them.
5029 // (I.e. there are no intra-region references that may be missed by the
5030 // remembered set)
5031 // - as soon there is a remembered set entry to the humongous starts region
5032 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5033 // until the end of a concurrent mark.
5034 //
5035 // It is not required to check whether the object has been found dead by marking
5036 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5037 // all objects allocated during that time are considered live.
5038 // SATB marking is even more conservative than the remembered set.
5039 // So if at this point in the collection there is no remembered set entry,
5040 // nobody has a reference to it.
5041 // At the start of collection we flush all refinement logs, and remembered sets
5042 // are completely up-to-date wrt to references to the humongous object.
5043 //
5044 // Other implementation considerations:
5045 // - never consider object arrays at this time because they would pose
5046 // considerable effort for cleaning up the the remembered sets. This is
5047 // required because stale remembered sets might reference locations that
5048 // are currently allocated into.
5049 uint region_idx = r->hrm_index();
5050 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5051 !r->rem_set()->is_empty()) {
5052 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",
5053 region_idx,
5054 (size_t)obj->size() * HeapWordSize,
5055 p2i(r->bottom()),
5056 r->rem_set()->occupied(),
5057 r->rem_set()->strong_code_roots_list_length(),
5058 next_bitmap->isMarked(r->bottom()),
5059 g1h->is_humongous_reclaim_candidate(region_idx),
5060 obj->is_typeArray()
5061 );
5062 return false;
5063 }
5064
5065 guarantee(obj->is_typeArray(),
5066 "Only eagerly reclaiming type arrays is supported, but the object "
5067 PTR_FORMAT " is not.", p2i(r->bottom()));
5068
5069 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",
5070 region_idx,
5071 (size_t)obj->size() * HeapWordSize,
5072 p2i(r->bottom()),
5073 r->rem_set()->occupied(),
5074 r->rem_set()->strong_code_roots_list_length(),
5075 next_bitmap->isMarked(r->bottom()),
5076 g1h->is_humongous_reclaim_candidate(region_idx),
5077 obj->is_typeArray()
5078 );
5079
5080 // Need to clear mark bit of the humongous object if already set.
5081 if (next_bitmap->isMarked(r->bottom())) {
5082 next_bitmap->clear(r->bottom());
5083 }
5084 do {
5085 HeapRegion* next = g1h->next_region_in_humongous(r);
5086 _freed_bytes += r->used();
5087 r->set_containing_set(NULL);
5088 _humongous_regions_removed++;
5089 g1h->free_humongous_region(r, _free_region_list, false);
5090 r = next;
5091 } while (r != NULL);
5092
5093 return false;
5094 }
5095
5096 uint humongous_free_count() {
5097 return _humongous_regions_removed;
5098 }
5099
5100 size_t bytes_freed() const {
5101 return _freed_bytes;
5102 }
5103 };
5104
5105 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5106 assert_at_safepoint(true);
5107
5108 if (!G1EagerReclaimHumongousObjects ||
5109 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5110 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5111 return;
5112 }
5113
5114 double start_time = os::elapsedTime();
5115
5116 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5117
5118 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5119 heap_region_iterate(&cl);
5120
5121 remove_from_old_sets(0, cl.humongous_free_count());
5122
5123 G1HRPrinter* hrp = hr_printer();
5124 if (hrp->is_active()) {
5125 FreeRegionListIterator iter(&local_cleanup_list);
5126 while (iter.more_available()) {
5127 HeapRegion* hr = iter.get_next();
5128 hrp->cleanup(hr);
5129 }
5130 }
5131
5132 prepend_to_freelist(&local_cleanup_list);
5133 decrement_summary_bytes(cl.bytes_freed());
5134
5135 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5136 cl.humongous_free_count());
5137 }
5138
5139 // This routine is similar to the above but does not record
5140 // any policy statistics or update free lists; we are abandoning
5141 // the current incremental collection set in preparation of a
5142 // full collection. After the full GC we will start to build up
5143 // the incremental collection set again.
5144 // This is only called when we're doing a full collection
5145 // and is immediately followed by the tearing down of the young list.
5146
5147 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5148 HeapRegion* cur = cs_head;
5149
5150 while (cur != NULL) {
5151 HeapRegion* next = cur->next_in_collection_set();
5152 assert(cur->in_collection_set(), "bad CS");
5153 cur->set_next_in_collection_set(NULL);
5154 clear_in_cset(cur);
5155 cur->set_young_index_in_cset(-1);
5156 cur = next;
5157 }
5158 }
5159
5160 void G1CollectedHeap::set_free_regions_coming() {
5161 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5162
5163 assert(!free_regions_coming(), "pre-condition");
5164 _free_regions_coming = true;
5165 }
5166
5167 void G1CollectedHeap::reset_free_regions_coming() {
5168 assert(free_regions_coming(), "pre-condition");
5169
5170 {
5171 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5172 _free_regions_coming = false;
5173 SecondaryFreeList_lock->notify_all();
5174 }
5175
5176 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5177 }
5178
5179 void G1CollectedHeap::wait_while_free_regions_coming() {
5180 // Most of the time we won't have to wait, so let's do a quick test
5181 // first before we take the lock.
5182 if (!free_regions_coming()) {
5183 return;
5184 }
5185
5186 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5187
5188 {
5189 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5190 while (free_regions_coming()) {
5191 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5192 }
5193 }
5194
5195 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5196 }
5197
5198 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5199 return _allocator->is_retained_old_region(hr);
5200 }
5201
5202 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5203 _young_list->push_region(hr);
5204 }
5205
5206 class NoYoungRegionsClosure: public HeapRegionClosure {
5207 private:
5208 bool _success;
5209 public:
5210 NoYoungRegionsClosure() : _success(true) { }
5211 bool doHeapRegion(HeapRegion* r) {
5212 if (r->is_young()) {
5213 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5214 p2i(r->bottom()), p2i(r->end()));
5215 _success = false;
5216 }
5217 return false;
5218 }
5219 bool success() { return _success; }
5220 };
5221
5222 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5223 bool ret = _young_list->check_list_empty();
5224
5225 if (check_heap) {
5226 NoYoungRegionsClosure closure;
5227 heap_region_iterate(&closure);
5228 ret = ret && closure.success();
5229 }
5230
5231 return ret;
5232 }
5233
5234 class TearDownRegionSetsClosure : public HeapRegionClosure {
5235 private:
5236 HeapRegionSet *_old_set;
5237
5238 public:
5239 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5240
5241 bool doHeapRegion(HeapRegion* r) {
5242 if (r->is_old()) {
5243 _old_set->remove(r);
5244 } else {
5245 // We ignore free regions, we'll empty the free list afterwards.
5246 // We ignore young regions, we'll empty the young list afterwards.
5247 // We ignore humongous regions, we're not tearing down the
5248 // humongous regions set.
5249 assert(r->is_free() || r->is_young() || r->is_humongous(),
5250 "it cannot be another type");
5251 }
5252 return false;
5253 }
5254
5255 ~TearDownRegionSetsClosure() {
5256 assert(_old_set->is_empty(), "post-condition");
5257 }
5258 };
5259
5260 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5261 assert_at_safepoint(true /* should_be_vm_thread */);
5262
5263 if (!free_list_only) {
5264 TearDownRegionSetsClosure cl(&_old_set);
5265 heap_region_iterate(&cl);
5266
5267 // Note that emptying the _young_list is postponed and instead done as
5268 // the first step when rebuilding the regions sets again. The reason for
5269 // this is that during a full GC string deduplication needs to know if
5270 // a collected region was young or old when the full GC was initiated.
5271 }
5272 _hrm.remove_all_free_regions();
5273 }
5274
5275 void G1CollectedHeap::increase_used(size_t bytes) {
5276 _summary_bytes_used += bytes;
5277 }
5278
5279 void G1CollectedHeap::decrease_used(size_t bytes) {
5280 assert(_summary_bytes_used >= bytes,
5281 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5282 _summary_bytes_used, bytes);
5283 _summary_bytes_used -= bytes;
5284 }
5285
5286 void G1CollectedHeap::set_used(size_t bytes) {
5287 _summary_bytes_used = bytes;
5288 }
5289
5290 class RebuildRegionSetsClosure : public HeapRegionClosure {
5291 private:
5292 bool _free_list_only;
5293 HeapRegionSet* _old_set;
5294 HeapRegionManager* _hrm;
5295 size_t _total_used;
5296
5297 public:
5298 RebuildRegionSetsClosure(bool free_list_only,
5299 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5300 _free_list_only(free_list_only),
5301 _old_set(old_set), _hrm(hrm), _total_used(0) {
5302 assert(_hrm->num_free_regions() == 0, "pre-condition");
5303 if (!free_list_only) {
5304 assert(_old_set->is_empty(), "pre-condition");
5305 }
5306 }
5307
5308 bool doHeapRegion(HeapRegion* r) {
5309 if (r->is_empty()) {
5310 // Add free regions to the free list
5311 r->set_free();
5312 r->set_allocation_context(AllocationContext::system());
5313 _hrm->insert_into_free_list(r);
5314 } else if (!_free_list_only) {
5315 assert(!r->is_young(), "we should not come across young regions");
5316
5317 if (r->is_humongous()) {
5318 // We ignore humongous regions. We left the humongous set unchanged.
5319 } else {
5320 // Objects that were compacted would have ended up on regions
5321 // that were previously old or free. Archive regions (which are
5322 // old) will not have been touched.
5323 assert(r->is_free() || r->is_old(), "invariant");
5324 // We now consider them old, so register as such. Leave
5325 // archive regions set that way, however, while still adding
5326 // them to the old set.
5327 if (!r->is_archive()) {
5328 r->set_old();
5329 }
5330 _old_set->add(r);
5331 }
5332 _total_used += r->used();
5333 }
5334
5335 return false;
5336 }
5337
5338 size_t total_used() {
5339 return _total_used;
5340 }
5341 };
5342
5343 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5344 assert_at_safepoint(true /* should_be_vm_thread */);
5345
5346 if (!free_list_only) {
5347 _young_list->empty_list();
5348 }
5349
5350 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5351 heap_region_iterate(&cl);
5352
5353 if (!free_list_only) {
5354 set_used(cl.total_used());
5355 if (_archive_allocator != NULL) {
5356 _archive_allocator->clear_used();
5357 }
5358 }
5359 assert(used_unlocked() == recalculate_used(),
5360 "inconsistent used_unlocked(), "
5361 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5362 used_unlocked(), recalculate_used());
5363 }
5364
5365 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5366 _refine_cte_cl->set_concurrent(concurrent);
5367 }
5368
5369 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5370 HeapRegion* hr = heap_region_containing(p);
5371 return hr->is_in(p);
5372 }
5373
5374 // Methods for the mutator alloc region
5375
5376 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5377 bool force) {
5378 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5379 assert(!force || g1_policy()->can_expand_young_list(),
5380 "if force is true we should be able to expand the young list");
5381 bool young_list_full = g1_policy()->is_young_list_full();
5382 if (force || !young_list_full) {
5383 HeapRegion* new_alloc_region = new_region(word_size,
5384 false /* is_old */,
5385 false /* do_expand */);
5386 if (new_alloc_region != NULL) {
5387 set_region_short_lived_locked(new_alloc_region);
5388 _hr_printer.alloc(new_alloc_region, young_list_full);
5389 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5390 return new_alloc_region;
5391 }
5392 }
5393 return NULL;
5394 }
5395
5396 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5397 size_t allocated_bytes) {
5398 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5399 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5400
5401 collection_set()->add_eden_region(alloc_region);
5402 increase_used(allocated_bytes);
5403 _hr_printer.retire(alloc_region);
5404 // We update the eden sizes here, when the region is retired,
5405 // instead of when it's allocated, since this is the point that its
5406 // used space has been recored in _summary_bytes_used.
5407 g1mm()->update_eden_size();
5408 }
5409
5410 // Methods for the GC alloc regions
5411
5412 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5413 uint count,
5414 InCSetState dest) {
5415 assert(FreeList_lock->owned_by_self(), "pre-condition");
5416
5417 if (count < g1_policy()->max_regions(dest)) {
5418 const bool is_survivor = (dest.is_young());
5419 HeapRegion* new_alloc_region = new_region(word_size,
5420 !is_survivor,
5421 true /* do_expand */);
5422 if (new_alloc_region != NULL) {
5423 // We really only need to do this for old regions given that we
5424 // should never scan survivors. But it doesn't hurt to do it
5425 // for survivors too.
5426 new_alloc_region->record_timestamp();
5427 if (is_survivor) {
5428 new_alloc_region->set_survivor();
5429 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5430 } else {
5431 new_alloc_region->set_old();
5432 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5433 }
5434 _hr_printer.alloc(new_alloc_region);
5435 bool during_im = collector_state()->during_initial_mark_pause();
5436 new_alloc_region->note_start_of_copying(during_im);
5437 return new_alloc_region;
5438 }
5439 }
5440 return NULL;
5441 }
5442
5443 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5444 size_t allocated_bytes,
5445 InCSetState dest) {
5446 bool during_im = collector_state()->during_initial_mark_pause();
5447 alloc_region->note_end_of_copying(during_im);
5448 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5449 if (dest.is_young()) {
5450 young_list()->add_survivor_region(alloc_region);
5451 } else {
5452 _old_set.add(alloc_region);
5453 }
5454 _hr_printer.retire(alloc_region);
5455 }
5456
5457 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5458 bool expanded = false;
5459 uint index = _hrm.find_highest_free(&expanded);
5460
5461 if (index != G1_NO_HRM_INDEX) {
5462 if (expanded) {
5463 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5464 HeapRegion::GrainWords * HeapWordSize);
5465 }
5466 _hrm.allocate_free_regions_starting_at(index, 1);
5467 return region_at(index);
5468 }
5469 return NULL;
5470 }
5471
5472 // Optimized nmethod scanning
5473
5474 class RegisterNMethodOopClosure: public OopClosure {
5475 G1CollectedHeap* _g1h;
5476 nmethod* _nm;
5477
5478 template <class T> void do_oop_work(T* p) {
5479 T heap_oop = oopDesc::load_heap_oop(p);
5480 if (!oopDesc::is_null(heap_oop)) {
5481 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5482 HeapRegion* hr = _g1h->heap_region_containing(obj);
5483 assert(!hr->is_continues_humongous(),
5484 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5485 " starting at " HR_FORMAT,
5486 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5487
5488 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5489 hr->add_strong_code_root_locked(_nm);
5490 }
5491 }
5492
5493 public:
5494 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5495 _g1h(g1h), _nm(nm) {}
5496
5497 void do_oop(oop* p) { do_oop_work(p); }
5498 void do_oop(narrowOop* p) { do_oop_work(p); }
5499 };
5500
5501 class UnregisterNMethodOopClosure: public OopClosure {
5502 G1CollectedHeap* _g1h;
5503 nmethod* _nm;
5504
5505 template <class T> void do_oop_work(T* p) {
5506 T heap_oop = oopDesc::load_heap_oop(p);
5507 if (!oopDesc::is_null(heap_oop)) {
5508 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5509 HeapRegion* hr = _g1h->heap_region_containing(obj);
5510 assert(!hr->is_continues_humongous(),
5511 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5512 " starting at " HR_FORMAT,
5513 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5514
5515 hr->remove_strong_code_root(_nm);
5516 }
5517 }
5518
5519 public:
5520 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5521 _g1h(g1h), _nm(nm) {}
5522
5523 void do_oop(oop* p) { do_oop_work(p); }
5524 void do_oop(narrowOop* p) { do_oop_work(p); }
5525 };
5526
5527 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5528 CollectedHeap::register_nmethod(nm);
5529
5530 guarantee(nm != NULL, "sanity");
5531 RegisterNMethodOopClosure reg_cl(this, nm);
5532 nm->oops_do(®_cl);
5533 }
5534
5535 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5536 CollectedHeap::unregister_nmethod(nm);
5537
5538 guarantee(nm != NULL, "sanity");
5539 UnregisterNMethodOopClosure reg_cl(this, nm);
5540 nm->oops_do(®_cl, true);
5541 }
5542
5543 void G1CollectedHeap::purge_code_root_memory() {
5544 double purge_start = os::elapsedTime();
5545 G1CodeRootSet::purge();
5546 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5547 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5548 }
5549
5550 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5551 G1CollectedHeap* _g1h;
5552
5553 public:
5554 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5555 _g1h(g1h) {}
5556
5557 void do_code_blob(CodeBlob* cb) {
5558 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5559 if (nm == NULL) {
5560 return;
5561 }
5562
5563 if (ScavengeRootsInCode) {
5564 _g1h->register_nmethod(nm);
5565 }
5566 }
5567 };
5568
5569 void G1CollectedHeap::rebuild_strong_code_roots() {
5570 RebuildStrongCodeRootClosure blob_cl(this);
5571 CodeCache::blobs_do(&blob_cl);
5572 }