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/g1CollectorPolicy.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1HeapTransition.hpp"
42 #include "gc/g1/g1HeapVerifier.hpp"
43 #include "gc/g1/g1MarkSweep.hpp"
44 #include "gc/g1/g1OopClosures.inline.hpp"
45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc/g1/g1RemSet.inline.hpp"
48 #include "gc/g1/g1RootClosures.hpp"
49 #include "gc/g1/g1RootProcessor.hpp"
50 #include "gc/g1/g1StringDedup.hpp"
51 #include "gc/g1/g1YCTypes.hpp"
52 #include "gc/g1/heapRegion.inline.hpp"
53 #include "gc/g1/heapRegionRemSet.hpp"
54 #include "gc/g1/heapRegionSet.inline.hpp"
55 #include "gc/g1/suspendibleThreadSet.hpp"
56 #include "gc/g1/vm_operations_g1.hpp"
57 #include "gc/shared/gcHeapSummary.hpp"
58 #include "gc/shared/gcId.hpp"
59 #include "gc/shared/gcLocker.inline.hpp"
60 #include "gc/shared/gcTimer.hpp"
61 #include "gc/shared/gcTrace.hpp"
62 #include "gc/shared/gcTraceTime.inline.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.inline.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "logging/log.hpp"
68 #include "memory/allocation.hpp"
69 #include "memory/iterator.hpp"
70 #include "oops/oop.inline.hpp"
71 #include "runtime/atomic.inline.hpp"
72 #include "runtime/init.hpp"
73 #include "runtime/orderAccess.inline.hpp"
74 #include "runtime/vmThread.hpp"
75 #include "utilities/globalDefinitions.hpp"
76 #include "utilities/stack.inline.hpp"
77
78 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
79
80 // INVARIANTS/NOTES
81 //
82 // All allocation activity covered by the G1CollectedHeap interface is
83 // serialized by acquiring the HeapLock. This happens in mem_allocate
84 // and allocate_new_tlab, which are the "entry" points to the
85 // allocation code from the rest of the JVM. (Note that this does not
86 // apply to TLAB allocation, which is not part of this interface: it
87 // is done by clients of this interface.)
88
89 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure() : _concurrent(true) { }
95
96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
98 // This path is executed by the concurrent refine or mutator threads,
99 // concurrently, and so we do not care if card_ptr contains references
100 // that point into the collection set.
101 assert(!oops_into_cset, "should be");
102
103 if (_concurrent && SuspendibleThreadSet::should_yield()) {
104 // Caller will actually yield.
105 return false;
106 }
107 // Otherwise, we finished successfully; return true.
108 return true;
109 }
110
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
113
114
115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
116 private:
117 size_t _num_dirtied;
118 G1CollectedHeap* _g1h;
119 G1SATBCardTableLoggingModRefBS* _g1_bs;
120
121 HeapRegion* region_for_card(jbyte* card_ptr) const {
122 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
123 }
124
125 bool will_become_free(HeapRegion* hr) const {
126 // A region will be freed by free_collection_set if the region is in the
127 // collection set and has not had an evacuation failure.
128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
129 }
130
131 public:
132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
133 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
134
135 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
136 HeapRegion* hr = region_for_card(card_ptr);
137
138 // Should only dirty cards in regions that won't be freed.
139 if (!will_become_free(hr)) {
140 *card_ptr = CardTableModRefBS::dirty_card_val();
141 _num_dirtied++;
142 }
143
144 return true;
145 }
146
147 size_t num_dirtied() const { return _num_dirtied; }
148 };
149
150
151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
152 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
153 }
154
155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
156 // The from card cache is not the memory that is actually committed. So we cannot
157 // take advantage of the zero_filled parameter.
158 reset_from_card_cache(start_idx, num_regions);
159 }
160
161 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
162 {
163 // Claim the right to put the region on the dirty cards region list
164 // by installing a self pointer.
165 HeapRegion* next = hr->get_next_dirty_cards_region();
166 if (next == NULL) {
167 HeapRegion* res = (HeapRegion*)
168 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
169 NULL);
170 if (res == NULL) {
171 HeapRegion* head;
172 do {
173 // Put the region to the dirty cards region list.
174 head = _dirty_cards_region_list;
175 next = (HeapRegion*)
176 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
177 if (next == head) {
178 assert(hr->get_next_dirty_cards_region() == hr,
179 "hr->get_next_dirty_cards_region() != hr");
180 if (next == NULL) {
181 // The last region in the list points to itself.
182 hr->set_next_dirty_cards_region(hr);
183 } else {
184 hr->set_next_dirty_cards_region(next);
185 }
186 }
187 } while (next != head);
188 }
189 }
190 }
191
192 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
193 {
194 HeapRegion* head;
195 HeapRegion* hr;
196 do {
197 head = _dirty_cards_region_list;
198 if (head == NULL) {
199 return NULL;
200 }
201 HeapRegion* new_head = head->get_next_dirty_cards_region();
202 if (head == new_head) {
203 // The last region.
204 new_head = NULL;
205 }
206 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
207 head);
208 } while (hr != head);
209 assert(hr != NULL, "invariant");
210 hr->set_next_dirty_cards_region(NULL);
211 return hr;
212 }
213
214 // Returns true if the reference points to an object that
215 // can move in an incremental collection.
216 bool G1CollectedHeap::is_scavengable(const void* p) {
217 HeapRegion* hr = heap_region_containing(p);
218 return !hr->is_pinned();
219 }
220
221 // Private methods.
222
223 HeapRegion*
224 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
225 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
226 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
227 if (!_secondary_free_list.is_empty()) {
228 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
229 "secondary_free_list has %u entries",
230 _secondary_free_list.length());
231 // It looks as if there are free regions available on the
232 // secondary_free_list. Let's move them to the free_list and try
233 // again to allocate from it.
234 append_secondary_free_list();
235
236 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
237 "empty we should have moved at least one entry to the free_list");
238 HeapRegion* res = _hrm.allocate_free_region(is_old);
239 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
240 "allocated " HR_FORMAT " from secondary_free_list",
241 HR_FORMAT_PARAMS(res));
242 return res;
243 }
244
245 // Wait here until we get notified either when (a) there are no
246 // more free regions coming or (b) some regions have been moved on
247 // the secondary_free_list.
248 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
249 }
250
251 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
252 "could not allocate from secondary_free_list");
253 return NULL;
254 }
255
256 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
257 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
258 "the only time we use this to allocate a humongous region is "
259 "when we are allocating a single humongous region");
260
261 HeapRegion* res;
262 if (G1StressConcRegionFreeing) {
263 if (!_secondary_free_list.is_empty()) {
264 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
265 "forced to look at the secondary_free_list");
266 res = new_region_try_secondary_free_list(is_old);
267 if (res != NULL) {
268 return res;
269 }
270 }
271 }
272
273 res = _hrm.allocate_free_region(is_old);
274
275 if (res == NULL) {
276 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
277 "res == NULL, trying the secondary_free_list");
278 res = new_region_try_secondary_free_list(is_old);
279 }
280 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
281 // Currently, only attempts to allocate GC alloc regions set
282 // do_expand to true. So, we should only reach here during a
283 // safepoint. If this assumption changes we might have to
284 // reconsider the use of _expand_heap_after_alloc_failure.
285 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
286
287 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
288 word_size * HeapWordSize);
289
290 if (expand(word_size * HeapWordSize)) {
291 // Given that expand() succeeded in expanding the heap, and we
292 // always expand the heap by an amount aligned to the heap
293 // region size, the free list should in theory not be empty.
294 // In either case allocate_free_region() will check for NULL.
295 res = _hrm.allocate_free_region(is_old);
296 } else {
297 _expand_heap_after_alloc_failure = false;
298 }
299 }
300 return res;
301 }
302
303 HeapWord*
304 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
305 uint num_regions,
306 size_t word_size,
307 AllocationContext_t context) {
308 assert(first != G1_NO_HRM_INDEX, "pre-condition");
309 assert(is_humongous(word_size), "word_size should be humongous");
310 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
311
312 // Index of last region in the series.
313 uint last = first + num_regions - 1;
314
315 // We need to initialize the region(s) we just discovered. This is
316 // a bit tricky given that it can happen concurrently with
317 // refinement threads refining cards on these regions and
318 // potentially wanting to refine the BOT as they are scanning
319 // those cards (this can happen shortly after a cleanup; see CR
320 // 6991377). So we have to set up the region(s) carefully and in
321 // a specific order.
322
323 // The word size sum of all the regions we will allocate.
324 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
325 assert(word_size <= word_size_sum, "sanity");
326
327 // This will be the "starts humongous" region.
328 HeapRegion* first_hr = region_at(first);
329 // The header of the new object will be placed at the bottom of
330 // the first region.
331 HeapWord* new_obj = first_hr->bottom();
332 // This will be the new top of the new object.
333 HeapWord* obj_top = new_obj + word_size;
334
335 // First, we need to zero the header of the space that we will be
336 // allocating. When we update top further down, some refinement
337 // threads might try to scan the region. By zeroing the header we
338 // ensure that any thread that will try to scan the region will
339 // come across the zero klass word and bail out.
340 //
341 // NOTE: It would not have been correct to have used
342 // CollectedHeap::fill_with_object() and make the space look like
343 // an int array. The thread that is doing the allocation will
344 // later update the object header to a potentially different array
345 // type and, for a very short period of time, the klass and length
346 // fields will be inconsistent. This could cause a refinement
347 // thread to calculate the object size incorrectly.
348 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
349
350 // How many words we use for filler objects.
351 size_t word_fill_size = word_size_sum - word_size;
352
353 // How many words memory we "waste" which cannot hold a filler object.
354 size_t words_not_fillable = 0;
355
356 if (word_fill_size >= min_fill_size()) {
357 fill_with_objects(obj_top, word_fill_size);
358 } else if (word_fill_size > 0) {
359 // We have space to fill, but we cannot fit an object there.
360 words_not_fillable = word_fill_size;
361 word_fill_size = 0;
362 }
363
364 // We will set up the first region as "starts humongous". This
365 // will also update the BOT covering all the regions to reflect
366 // that there is a single object that starts at the bottom of the
367 // first region.
368 first_hr->set_starts_humongous(obj_top, word_fill_size);
369 first_hr->set_allocation_context(context);
370 // Then, if there are any, we will set up the "continues
371 // humongous" regions.
372 HeapRegion* hr = NULL;
373 for (uint i = first + 1; i <= last; ++i) {
374 hr = region_at(i);
375 hr->set_continues_humongous(first_hr);
376 hr->set_allocation_context(context);
377 }
378
379 // Up to this point no concurrent thread would have been able to
380 // do any scanning on any region in this series. All the top
381 // fields still point to bottom, so the intersection between
382 // [bottom,top] and [card_start,card_end] will be empty. Before we
383 // update the top fields, we'll do a storestore to make sure that
384 // no thread sees the update to top before the zeroing of the
385 // object header and the BOT initialization.
386 OrderAccess::storestore();
387
388 // Now, we will update the top fields of the "continues humongous"
389 // regions except the last one.
390 for (uint i = first; i < last; ++i) {
391 hr = region_at(i);
392 hr->set_top(hr->end());
393 }
394
395 hr = region_at(last);
396 // If we cannot fit a filler object, we must set top to the end
397 // of the humongous object, otherwise we cannot iterate the heap
398 // and the BOT will not be complete.
399 hr->set_top(hr->end() - words_not_fillable);
400
401 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
402 "obj_top should be in last region");
403
404 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
405
406 assert(words_not_fillable == 0 ||
407 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
408 "Miscalculation in humongous allocation");
409
410 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
411
412 for (uint i = first; i <= last; ++i) {
413 hr = region_at(i);
414 _humongous_set.add(hr);
415 _hr_printer.alloc(hr);
416 }
417
418 return new_obj;
419 }
420
421 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
422 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
423 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
424 }
425
426 // If could fit into free regions w/o expansion, try.
427 // Otherwise, if can expand, do so.
428 // Otherwise, if using ex regions might help, try with ex given back.
429 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
430 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
431
432 _verifier->verify_region_sets_optional();
433
434 uint first = G1_NO_HRM_INDEX;
435 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
436
437 if (obj_regions == 1) {
438 // Only one region to allocate, try to use a fast path by directly allocating
439 // from the free lists. Do not try to expand here, we will potentially do that
440 // later.
441 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
442 if (hr != NULL) {
443 first = hr->hrm_index();
444 }
445 } else {
446 // We can't allocate humongous regions spanning more than one region while
447 // cleanupComplete() is running, since some of the regions we find to be
448 // empty might not yet be added to the free list. It is not straightforward
449 // to know in which list they are on so that we can remove them. We only
450 // need to do this if we need to allocate more than one region to satisfy the
451 // current humongous allocation request. If we are only allocating one region
452 // we use the one-region region allocation code (see above), that already
453 // potentially waits for regions from the secondary free list.
454 wait_while_free_regions_coming();
455 append_secondary_free_list_if_not_empty_with_lock();
456
457 // Policy: Try only empty regions (i.e. already committed first). Maybe we
458 // are lucky enough to find some.
459 first = _hrm.find_contiguous_only_empty(obj_regions);
460 if (first != G1_NO_HRM_INDEX) {
461 _hrm.allocate_free_regions_starting_at(first, obj_regions);
462 }
463 }
464
465 if (first == G1_NO_HRM_INDEX) {
466 // Policy: We could not find enough regions for the humongous object in the
467 // free list. Look through the heap to find a mix of free and uncommitted regions.
468 // If so, try expansion.
469 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
470 if (first != G1_NO_HRM_INDEX) {
471 // We found something. Make sure these regions are committed, i.e. expand
472 // the heap. Alternatively we could do a defragmentation GC.
473 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
474 word_size * HeapWordSize);
475
476
477 _hrm.expand_at(first, obj_regions);
478 g1_policy()->record_new_heap_size(num_regions());
479
480 #ifdef ASSERT
481 for (uint i = first; i < first + obj_regions; ++i) {
482 HeapRegion* hr = region_at(i);
483 assert(hr->is_free(), "sanity");
484 assert(hr->is_empty(), "sanity");
485 assert(is_on_master_free_list(hr), "sanity");
486 }
487 #endif
488 _hrm.allocate_free_regions_starting_at(first, obj_regions);
489 } else {
490 // Policy: Potentially trigger a defragmentation GC.
491 }
492 }
493
494 HeapWord* result = NULL;
495 if (first != G1_NO_HRM_INDEX) {
496 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
497 word_size, context);
498 assert(result != NULL, "it should always return a valid result");
499
500 // A successful humongous object allocation changes the used space
501 // information of the old generation so we need to recalculate the
502 // sizes and update the jstat counters here.
503 g1mm()->update_sizes();
504 }
505
506 _verifier->verify_region_sets_optional();
507
508 return result;
509 }
510
511 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
512 assert_heap_not_locked_and_not_at_safepoint();
513 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
514
515 uint dummy_gc_count_before;
516 uint dummy_gclocker_retry_count = 0;
517 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
518 }
519
520 HeapWord*
521 G1CollectedHeap::mem_allocate(size_t word_size,
522 bool* gc_overhead_limit_was_exceeded) {
523 assert_heap_not_locked_and_not_at_safepoint();
524
525 // Loop until the allocation is satisfied, or unsatisfied after GC.
526 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
527 uint gc_count_before;
528
529 HeapWord* result = NULL;
530 if (!is_humongous(word_size)) {
531 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
532 } else {
533 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
534 }
535 if (result != NULL) {
536 return result;
537 }
538
539 // Create the garbage collection operation...
540 VM_G1CollectForAllocation op(gc_count_before, word_size);
541 op.set_allocation_context(AllocationContext::current());
542
543 // ...and get the VM thread to execute it.
544 VMThread::execute(&op);
545
546 if (op.prologue_succeeded() && op.pause_succeeded()) {
547 // If the operation was successful we'll return the result even
548 // if it is NULL. If the allocation attempt failed immediately
549 // after a Full GC, it's unlikely we'll be able to allocate now.
550 HeapWord* result = op.result();
551 if (result != NULL && !is_humongous(word_size)) {
552 // Allocations that take place on VM operations do not do any
553 // card dirtying and we have to do it here. We only have to do
554 // this for non-humongous allocations, though.
555 dirty_young_block(result, word_size);
556 }
557 return result;
558 } else {
559 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
560 return NULL;
561 }
562 assert(op.result() == NULL,
563 "the result should be NULL if the VM op did not succeed");
564 }
565
566 // Give a warning if we seem to be looping forever.
567 if ((QueuedAllocationWarningCount > 0) &&
568 (try_count % QueuedAllocationWarningCount == 0)) {
569 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
570 }
571 }
572
573 ShouldNotReachHere();
574 return NULL;
575 }
576
577 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
578 AllocationContext_t context,
579 uint* gc_count_before_ret,
580 uint* gclocker_retry_count_ret) {
581 // Make sure you read the note in attempt_allocation_humongous().
582
583 assert_heap_not_locked_and_not_at_safepoint();
584 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
585 "be called for humongous allocation requests");
586
587 // We should only get here after the first-level allocation attempt
588 // (attempt_allocation()) failed to allocate.
589
590 // We will loop until a) we manage to successfully perform the
591 // allocation or b) we successfully schedule a collection which
592 // fails to perform the allocation. b) is the only case when we'll
593 // return NULL.
594 HeapWord* result = NULL;
595 for (int try_count = 1; /* we'll return */; try_count += 1) {
596 bool should_try_gc;
597 uint gc_count_before;
598
599 {
600 MutexLockerEx x(Heap_lock);
601 result = _allocator->attempt_allocation_locked(word_size, context);
602 if (result != NULL) {
603 return result;
604 }
605
606 if (GCLocker::is_active_and_needs_gc()) {
607 if (g1_policy()->can_expand_young_list()) {
608 // No need for an ergo verbose message here,
609 // can_expand_young_list() does this when it returns true.
610 result = _allocator->attempt_allocation_force(word_size, context);
611 if (result != NULL) {
612 return result;
613 }
614 }
615 should_try_gc = false;
616 } else {
617 // The GCLocker may not be active but the GCLocker initiated
618 // GC may not yet have been performed (GCLocker::needs_gc()
619 // returns true). In this case we do not try this GC and
620 // wait until the GCLocker initiated GC is performed, and
621 // then retry the allocation.
622 if (GCLocker::needs_gc()) {
623 should_try_gc = false;
624 } else {
625 // Read the GC count while still holding the Heap_lock.
626 gc_count_before = total_collections();
627 should_try_gc = true;
628 }
629 }
630 }
631
632 if (should_try_gc) {
633 bool succeeded;
634 result = do_collection_pause(word_size, gc_count_before, &succeeded,
635 GCCause::_g1_inc_collection_pause);
636 if (result != NULL) {
637 assert(succeeded, "only way to get back a non-NULL result");
638 return result;
639 }
640
641 if (succeeded) {
642 // If we get here we successfully scheduled a collection which
643 // failed to allocate. No point in trying to allocate
644 // further. We'll just return NULL.
645 MutexLockerEx x(Heap_lock);
646 *gc_count_before_ret = total_collections();
647 return NULL;
648 }
649 } else {
650 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
651 MutexLockerEx x(Heap_lock);
652 *gc_count_before_ret = total_collections();
653 return NULL;
654 }
655 // The GCLocker is either active or the GCLocker initiated
656 // GC has not yet been performed. Stall until it is and
657 // then retry the allocation.
658 GCLocker::stall_until_clear();
659 (*gclocker_retry_count_ret) += 1;
660 }
661
662 // We can reach here if we were unsuccessful in scheduling a
663 // collection (because another thread beat us to it) or if we were
664 // stalled due to the GC locker. In either can we should retry the
665 // allocation attempt in case another thread successfully
666 // performed a collection and reclaimed enough space. We do the
667 // first attempt (without holding the Heap_lock) here and the
668 // follow-on attempt will be at the start of the next loop
669 // iteration (after taking the Heap_lock).
670 result = _allocator->attempt_allocation(word_size, context);
671 if (result != NULL) {
672 return result;
673 }
674
675 // Give a warning if we seem to be looping forever.
676 if ((QueuedAllocationWarningCount > 0) &&
677 (try_count % QueuedAllocationWarningCount == 0)) {
678 warning("G1CollectedHeap::attempt_allocation_slow() "
679 "retries %d times", try_count);
680 }
681 }
682
683 ShouldNotReachHere();
684 return NULL;
685 }
686
687 void G1CollectedHeap::begin_archive_alloc_range() {
688 assert_at_safepoint(true /* should_be_vm_thread */);
689 if (_archive_allocator == NULL) {
690 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
691 }
692 }
693
694 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
695 // Allocations in archive regions cannot be of a size that would be considered
696 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
697 // may be different at archive-restore time.
698 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
699 }
700
701 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
702 assert_at_safepoint(true /* should_be_vm_thread */);
703 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
704 if (is_archive_alloc_too_large(word_size)) {
705 return NULL;
706 }
707 return _archive_allocator->archive_mem_allocate(word_size);
708 }
709
710 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
711 size_t end_alignment_in_bytes) {
712 assert_at_safepoint(true /* should_be_vm_thread */);
713 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
714
715 // Call complete_archive to do the real work, filling in the MemRegion
716 // array with the archive regions.
717 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
718 delete _archive_allocator;
719 _archive_allocator = NULL;
720 }
721
722 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
723 assert(ranges != NULL, "MemRegion array NULL");
724 assert(count != 0, "No MemRegions provided");
725 MemRegion reserved = _hrm.reserved();
726 for (size_t i = 0; i < count; i++) {
727 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
728 return false;
729 }
730 }
731 return true;
732 }
733
734 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
735 assert(!is_init_completed(), "Expect to be called at JVM init time");
736 assert(ranges != NULL, "MemRegion array NULL");
737 assert(count != 0, "No MemRegions provided");
738 MutexLockerEx x(Heap_lock);
739
740 MemRegion reserved = _hrm.reserved();
741 HeapWord* prev_last_addr = NULL;
742 HeapRegion* prev_last_region = NULL;
743
744 // Temporarily disable pretouching of heap pages. This interface is used
745 // when mmap'ing archived heap data in, so pre-touching is wasted.
746 FlagSetting fs(AlwaysPreTouch, false);
747
748 // Enable archive object checking in G1MarkSweep. We have to let it know
749 // about each archive range, so that objects in those ranges aren't marked.
750 G1MarkSweep::enable_archive_object_check();
751
752 // For each specified MemRegion range, allocate the corresponding G1
753 // regions and mark them as archive regions. We expect the ranges in
754 // ascending starting address order, without overlap.
755 for (size_t i = 0; i < count; i++) {
756 MemRegion curr_range = ranges[i];
757 HeapWord* start_address = curr_range.start();
758 size_t word_size = curr_range.word_size();
759 HeapWord* last_address = curr_range.last();
760 size_t commits = 0;
761
762 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
763 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
764 p2i(start_address), p2i(last_address));
765 guarantee(start_address > prev_last_addr,
766 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
767 p2i(start_address), p2i(prev_last_addr));
768 prev_last_addr = last_address;
769
770 // Check for ranges that start in the same G1 region in which the previous
771 // range ended, and adjust the start address so we don't try to allocate
772 // the same region again. If the current range is entirely within that
773 // region, skip it, just adjusting the recorded top.
774 HeapRegion* start_region = _hrm.addr_to_region(start_address);
775 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
776 start_address = start_region->end();
777 if (start_address > last_address) {
778 increase_used(word_size * HeapWordSize);
779 start_region->set_top(last_address + 1);
780 continue;
781 }
782 start_region->set_top(start_address);
783 curr_range = MemRegion(start_address, last_address + 1);
784 start_region = _hrm.addr_to_region(start_address);
785 }
786
787 // Perform the actual region allocation, exiting if it fails.
788 // Then note how much new space we have allocated.
789 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
790 return false;
791 }
792 increase_used(word_size * HeapWordSize);
793 if (commits != 0) {
794 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
795 HeapRegion::GrainWords * HeapWordSize * commits);
796
797 }
798
799 // Mark each G1 region touched by the range as archive, add it to the old set,
800 // and set the allocation context and top.
801 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
802 HeapRegion* last_region = _hrm.addr_to_region(last_address);
803 prev_last_region = last_region;
804
805 while (curr_region != NULL) {
806 assert(curr_region->is_empty() && !curr_region->is_pinned(),
807 "Region already in use (index %u)", curr_region->hrm_index());
808 curr_region->set_allocation_context(AllocationContext::system());
809 curr_region->set_archive();
810 _hr_printer.alloc(curr_region);
811 _old_set.add(curr_region);
812 if (curr_region != last_region) {
813 curr_region->set_top(curr_region->end());
814 curr_region = _hrm.next_region_in_heap(curr_region);
815 } else {
816 curr_region->set_top(last_address + 1);
817 curr_region = NULL;
818 }
819 }
820
821 // Notify mark-sweep of the archive range.
822 G1MarkSweep::set_range_archive(curr_range, true);
823 }
824 return true;
825 }
826
827 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
828 assert(!is_init_completed(), "Expect to be called at JVM init time");
829 assert(ranges != NULL, "MemRegion array NULL");
830 assert(count != 0, "No MemRegions provided");
831 MemRegion reserved = _hrm.reserved();
832 HeapWord *prev_last_addr = NULL;
833 HeapRegion* prev_last_region = NULL;
834
835 // For each MemRegion, create filler objects, if needed, in the G1 regions
836 // that contain the address range. The address range actually within the
837 // MemRegion will not be modified. That is assumed to have been initialized
838 // elsewhere, probably via an mmap of archived heap data.
839 MutexLockerEx x(Heap_lock);
840 for (size_t i = 0; i < count; i++) {
841 HeapWord* start_address = ranges[i].start();
842 HeapWord* last_address = ranges[i].last();
843
844 assert(reserved.contains(start_address) && reserved.contains(last_address),
845 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
846 p2i(start_address), p2i(last_address));
847 assert(start_address > prev_last_addr,
848 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
849 p2i(start_address), p2i(prev_last_addr));
850
851 HeapRegion* start_region = _hrm.addr_to_region(start_address);
852 HeapRegion* last_region = _hrm.addr_to_region(last_address);
853 HeapWord* bottom_address = start_region->bottom();
854
855 // Check for a range beginning in the same region in which the
856 // previous one ended.
857 if (start_region == prev_last_region) {
858 bottom_address = prev_last_addr + 1;
859 }
860
861 // Verify that the regions were all marked as archive regions by
862 // alloc_archive_regions.
863 HeapRegion* curr_region = start_region;
864 while (curr_region != NULL) {
865 guarantee(curr_region->is_archive(),
866 "Expected archive region at index %u", curr_region->hrm_index());
867 if (curr_region != last_region) {
868 curr_region = _hrm.next_region_in_heap(curr_region);
869 } else {
870 curr_region = NULL;
871 }
872 }
873
874 prev_last_addr = last_address;
875 prev_last_region = last_region;
876
877 // Fill the memory below the allocated range with dummy object(s),
878 // if the region bottom does not match the range start, or if the previous
879 // range ended within the same G1 region, and there is a gap.
880 if (start_address != bottom_address) {
881 size_t fill_size = pointer_delta(start_address, bottom_address);
882 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
883 increase_used(fill_size * HeapWordSize);
884 }
885 }
886 }
887
888 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
889 uint* gc_count_before_ret,
890 uint* gclocker_retry_count_ret) {
891 assert_heap_not_locked_and_not_at_safepoint();
892 assert(!is_humongous(word_size), "attempt_allocation() should not "
893 "be called for humongous allocation requests");
894
895 AllocationContext_t context = AllocationContext::current();
896 HeapWord* result = _allocator->attempt_allocation(word_size, context);
897
898 if (result == NULL) {
899 result = attempt_allocation_slow(word_size,
900 context,
901 gc_count_before_ret,
902 gclocker_retry_count_ret);
903 }
904 assert_heap_not_locked();
905 if (result != NULL) {
906 dirty_young_block(result, word_size);
907 }
908 return result;
909 }
910
911 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
912 assert(!is_init_completed(), "Expect to be called at JVM init time");
913 assert(ranges != NULL, "MemRegion array NULL");
914 assert(count != 0, "No MemRegions provided");
915 MemRegion reserved = _hrm.reserved();
916 HeapWord* prev_last_addr = NULL;
917 HeapRegion* prev_last_region = NULL;
918 size_t size_used = 0;
919 size_t uncommitted_regions = 0;
920
921 // For each Memregion, free the G1 regions that constitute it, and
922 // notify mark-sweep that the range is no longer to be considered 'archive.'
923 MutexLockerEx x(Heap_lock);
924 for (size_t i = 0; i < count; i++) {
925 HeapWord* start_address = ranges[i].start();
926 HeapWord* last_address = ranges[i].last();
927
928 assert(reserved.contains(start_address) && reserved.contains(last_address),
929 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
930 p2i(start_address), p2i(last_address));
931 assert(start_address > prev_last_addr,
932 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
933 p2i(start_address), p2i(prev_last_addr));
934 size_used += ranges[i].byte_size();
935 prev_last_addr = last_address;
936
937 HeapRegion* start_region = _hrm.addr_to_region(start_address);
938 HeapRegion* last_region = _hrm.addr_to_region(last_address);
939
940 // Check for ranges that start in the same G1 region in which the previous
941 // range ended, and adjust the start address so we don't try to free
942 // the same region again. If the current range is entirely within that
943 // region, skip it.
944 if (start_region == prev_last_region) {
945 start_address = start_region->end();
946 if (start_address > last_address) {
947 continue;
948 }
949 start_region = _hrm.addr_to_region(start_address);
950 }
951 prev_last_region = last_region;
952
953 // After verifying that each region was marked as an archive region by
954 // alloc_archive_regions, set it free and empty and uncommit it.
955 HeapRegion* curr_region = start_region;
956 while (curr_region != NULL) {
957 guarantee(curr_region->is_archive(),
958 "Expected archive region at index %u", curr_region->hrm_index());
959 uint curr_index = curr_region->hrm_index();
960 _old_set.remove(curr_region);
961 curr_region->set_free();
962 curr_region->set_top(curr_region->bottom());
963 if (curr_region != last_region) {
964 curr_region = _hrm.next_region_in_heap(curr_region);
965 } else {
966 curr_region = NULL;
967 }
968 _hrm.shrink_at(curr_index, 1);
969 uncommitted_regions++;
970 }
971
972 // Notify mark-sweep that this is no longer an archive range.
973 G1MarkSweep::set_range_archive(ranges[i], false);
974 }
975
976 if (uncommitted_regions != 0) {
977 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
978 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
979 }
980 decrease_used(size_used);
981 }
982
983 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
984 uint* gc_count_before_ret,
985 uint* gclocker_retry_count_ret) {
986 // The structure of this method has a lot of similarities to
987 // attempt_allocation_slow(). The reason these two were not merged
988 // into a single one is that such a method would require several "if
989 // allocation is not humongous do this, otherwise do that"
990 // conditional paths which would obscure its flow. In fact, an early
991 // version of this code did use a unified method which was harder to
992 // follow and, as a result, it had subtle bugs that were hard to
993 // track down. So keeping these two methods separate allows each to
994 // be more readable. It will be good to keep these two in sync as
995 // much as possible.
996
997 assert_heap_not_locked_and_not_at_safepoint();
998 assert(is_humongous(word_size), "attempt_allocation_humongous() "
999 "should only be called for humongous allocations");
1000
1001 // Humongous objects can exhaust the heap quickly, so we should check if we
1002 // need to start a marking cycle at each humongous object allocation. We do
1003 // the check before we do the actual allocation. The reason for doing it
1004 // before the allocation is that we avoid having to keep track of the newly
1005 // allocated memory while we do a GC.
1006 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1007 word_size)) {
1008 collect(GCCause::_g1_humongous_allocation);
1009 }
1010
1011 // We will loop until a) we manage to successfully perform the
1012 // allocation or b) we successfully schedule a collection which
1013 // fails to perform the allocation. b) is the only case when we'll
1014 // return NULL.
1015 HeapWord* result = NULL;
1016 for (int try_count = 1; /* we'll return */; try_count += 1) {
1017 bool should_try_gc;
1018 uint gc_count_before;
1019
1020 {
1021 MutexLockerEx x(Heap_lock);
1022
1023 // Given that humongous objects are not allocated in young
1024 // regions, we'll first try to do the allocation without doing a
1025 // collection hoping that there's enough space in the heap.
1026 result = humongous_obj_allocate(word_size, AllocationContext::current());
1027 if (result != NULL) {
1028 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1029 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1030 return result;
1031 }
1032
1033 if (GCLocker::is_active_and_needs_gc()) {
1034 should_try_gc = false;
1035 } else {
1036 // The GCLocker may not be active but the GCLocker initiated
1037 // GC may not yet have been performed (GCLocker::needs_gc()
1038 // returns true). In this case we do not try this GC and
1039 // wait until the GCLocker initiated GC is performed, and
1040 // then retry the allocation.
1041 if (GCLocker::needs_gc()) {
1042 should_try_gc = false;
1043 } else {
1044 // Read the GC count while still holding the Heap_lock.
1045 gc_count_before = total_collections();
1046 should_try_gc = true;
1047 }
1048 }
1049 }
1050
1051 if (should_try_gc) {
1052 // If we failed to allocate the humongous object, we should try to
1053 // do a collection pause (if we're allowed) in case it reclaims
1054 // enough space for the allocation to succeed after the pause.
1055
1056 bool succeeded;
1057 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1058 GCCause::_g1_humongous_allocation);
1059 if (result != NULL) {
1060 assert(succeeded, "only way to get back a non-NULL result");
1061 return result;
1062 }
1063
1064 if (succeeded) {
1065 // If we get here we successfully scheduled a collection which
1066 // failed to allocate. No point in trying to allocate
1067 // further. We'll just return NULL.
1068 MutexLockerEx x(Heap_lock);
1069 *gc_count_before_ret = total_collections();
1070 return NULL;
1071 }
1072 } else {
1073 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1074 MutexLockerEx x(Heap_lock);
1075 *gc_count_before_ret = total_collections();
1076 return NULL;
1077 }
1078 // The GCLocker is either active or the GCLocker initiated
1079 // GC has not yet been performed. Stall until it is and
1080 // then retry the allocation.
1081 GCLocker::stall_until_clear();
1082 (*gclocker_retry_count_ret) += 1;
1083 }
1084
1085 // We can reach here if we were unsuccessful in scheduling a
1086 // collection (because another thread beat us to it) or if we were
1087 // stalled due to the GC locker. In either can we should retry the
1088 // allocation attempt in case another thread successfully
1089 // performed a collection and reclaimed enough space. Give a
1090 // warning if we seem to be looping forever.
1091
1092 if ((QueuedAllocationWarningCount > 0) &&
1093 (try_count % QueuedAllocationWarningCount == 0)) {
1094 warning("G1CollectedHeap::attempt_allocation_humongous() "
1095 "retries %d times", try_count);
1096 }
1097 }
1098
1099 ShouldNotReachHere();
1100 return NULL;
1101 }
1102
1103 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1104 AllocationContext_t context,
1105 bool expect_null_mutator_alloc_region) {
1106 assert_at_safepoint(true /* should_be_vm_thread */);
1107 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1108 "the current alloc region was unexpectedly found to be non-NULL");
1109
1110 if (!is_humongous(word_size)) {
1111 return _allocator->attempt_allocation_locked(word_size, context);
1112 } else {
1113 HeapWord* result = humongous_obj_allocate(word_size, context);
1114 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1115 collector_state()->set_initiate_conc_mark_if_possible(true);
1116 }
1117 return result;
1118 }
1119
1120 ShouldNotReachHere();
1121 }
1122
1123 class PostMCRemSetClearClosure: public HeapRegionClosure {
1124 G1CollectedHeap* _g1h;
1125 ModRefBarrierSet* _mr_bs;
1126 public:
1127 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1128 _g1h(g1h), _mr_bs(mr_bs) {}
1129
1130 bool doHeapRegion(HeapRegion* r) {
1131 HeapRegionRemSet* hrrs = r->rem_set();
1132
1133 _g1h->reset_gc_time_stamps(r);
1134
1135 if (r->is_continues_humongous()) {
1136 // We'll assert that the strong code root list and RSet is empty
1137 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1138 assert(hrrs->occupied() == 0, "RSet should be empty");
1139 } else {
1140 hrrs->clear();
1141 }
1142 // You might think here that we could clear just the cards
1143 // corresponding to the used region. But no: if we leave a dirty card
1144 // in a region we might allocate into, then it would prevent that card
1145 // from being enqueued, and cause it to be missed.
1146 // Re: the performance cost: we shouldn't be doing full GC anyway!
1147 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1148
1149 return false;
1150 }
1151 };
1152
1153 void G1CollectedHeap::clear_rsets_post_compaction() {
1154 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1155 heap_region_iterate(&rs_clear);
1156 }
1157
1158 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1159 G1CollectedHeap* _g1h;
1160 UpdateRSOopClosure _cl;
1161 public:
1162 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1163 _cl(g1->g1_rem_set(), worker_i),
1164 _g1h(g1)
1165 { }
1166
1167 bool doHeapRegion(HeapRegion* r) {
1168 if (!r->is_continues_humongous()) {
1169 _cl.set_from(r);
1170 r->oop_iterate(&_cl);
1171 }
1172 return false;
1173 }
1174 };
1175
1176 class ParRebuildRSTask: public AbstractGangTask {
1177 G1CollectedHeap* _g1;
1178 HeapRegionClaimer _hrclaimer;
1179
1180 public:
1181 ParRebuildRSTask(G1CollectedHeap* g1) :
1182 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1183
1184 void work(uint worker_id) {
1185 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1186 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1187 }
1188 };
1189
1190 class PostCompactionPrinterClosure: public HeapRegionClosure {
1191 private:
1192 G1HRPrinter* _hr_printer;
1193 public:
1194 bool doHeapRegion(HeapRegion* hr) {
1195 assert(!hr->is_young(), "not expecting to find young regions");
1196 _hr_printer->post_compaction(hr);
1197 return false;
1198 }
1199
1200 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1201 : _hr_printer(hr_printer) { }
1202 };
1203
1204 void G1CollectedHeap::print_hrm_post_compaction() {
1205 if (_hr_printer.is_active()) {
1206 PostCompactionPrinterClosure cl(hr_printer());
1207 heap_region_iterate(&cl);
1208 }
1209
1210 }
1211
1212 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1213 bool clear_all_soft_refs) {
1214 assert_at_safepoint(true /* should_be_vm_thread */);
1215
1216 if (GCLocker::check_active_before_gc()) {
1217 return false;
1218 }
1219
1220 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1221 gc_timer->register_gc_start();
1222
1223 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1224 GCIdMark gc_id_mark;
1225 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1226
1227 SvcGCMarker sgcm(SvcGCMarker::FULL);
1228 ResourceMark rm;
1229
1230 print_heap_before_gc();
1231 trace_heap_before_gc(gc_tracer);
1232
1233 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1234
1235 _verifier->verify_region_sets_optional();
1236
1237 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1238 collector_policy()->should_clear_all_soft_refs();
1239
1240 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1241
1242 {
1243 IsGCActiveMark x;
1244
1245 // Timing
1246 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1247 GCTraceCPUTime tcpu;
1248
1249 {
1250 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1251 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1252 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1253
1254 G1HeapTransition heap_transition(this);
1255 g1_policy()->record_full_collection_start();
1256
1257 // Note: When we have a more flexible GC logging framework that
1258 // allows us to add optional attributes to a GC log record we
1259 // could consider timing and reporting how long we wait in the
1260 // following two methods.
1261 wait_while_free_regions_coming();
1262 // If we start the compaction before the CM threads finish
1263 // scanning the root regions we might trip them over as we'll
1264 // be moving objects / updating references. So let's wait until
1265 // they are done. By telling them to abort, they should complete
1266 // early.
1267 _cm->root_regions()->abort();
1268 _cm->root_regions()->wait_until_scan_finished();
1269 append_secondary_free_list_if_not_empty_with_lock();
1270
1271 gc_prologue(true);
1272 increment_total_collections(true /* full gc */);
1273 increment_old_marking_cycles_started();
1274
1275 assert(used() == recalculate_used(), "Should be equal");
1276
1277 _verifier->verify_before_gc();
1278
1279 _verifier->check_bitmaps("Full GC Start");
1280 pre_full_gc_dump(gc_timer);
1281
1282 #if defined(COMPILER2) || INCLUDE_JVMCI
1283 DerivedPointerTable::clear();
1284 #endif
1285
1286 // Disable discovery and empty the discovered lists
1287 // for the CM ref processor.
1288 ref_processor_cm()->disable_discovery();
1289 ref_processor_cm()->abandon_partial_discovery();
1290 ref_processor_cm()->verify_no_references_recorded();
1291
1292 // Abandon current iterations of concurrent marking and concurrent
1293 // refinement, if any are in progress. We have to do this before
1294 // wait_until_scan_finished() below.
1295 concurrent_mark()->abort();
1296
1297 // Make sure we'll choose a new allocation region afterwards.
1298 _allocator->release_mutator_alloc_region();
1299 _allocator->abandon_gc_alloc_regions();
1300 g1_rem_set()->cleanupHRRS();
1301
1302 // We may have added regions to the current incremental collection
1303 // set between the last GC or pause and now. We need to clear the
1304 // incremental collection set and then start rebuilding it afresh
1305 // after this full GC.
1306 abandon_collection_set(g1_policy()->inc_cset_head());
1307 g1_policy()->clear_incremental_cset();
1308 g1_policy()->stop_incremental_cset_building();
1309
1310 tear_down_region_sets(false /* free_list_only */);
1311 collector_state()->set_gcs_are_young(true);
1312
1313 // See the comments in g1CollectedHeap.hpp and
1314 // G1CollectedHeap::ref_processing_init() about
1315 // how reference processing currently works in G1.
1316
1317 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1318 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1319
1320 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1321 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1322
1323 ref_processor_stw()->enable_discovery();
1324 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1325
1326 // Do collection work
1327 {
1328 HandleMark hm; // Discard invalid handles created during gc
1329 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1330 }
1331
1332 assert(num_free_regions() == 0, "we should not have added any free regions");
1333 rebuild_region_sets(false /* free_list_only */);
1334
1335 // Enqueue any discovered reference objects that have
1336 // not been removed from the discovered lists.
1337 ref_processor_stw()->enqueue_discovered_references();
1338
1339 #if defined(COMPILER2) || INCLUDE_JVMCI
1340 DerivedPointerTable::update_pointers();
1341 #endif
1342
1343 MemoryService::track_memory_usage();
1344
1345 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1346 ref_processor_stw()->verify_no_references_recorded();
1347
1348 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1349 ClassLoaderDataGraph::purge();
1350 MetaspaceAux::verify_metrics();
1351
1352 // Note: since we've just done a full GC, concurrent
1353 // marking is no longer active. Therefore we need not
1354 // re-enable reference discovery for the CM ref processor.
1355 // That will be done at the start of the next marking cycle.
1356 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1357 ref_processor_cm()->verify_no_references_recorded();
1358
1359 reset_gc_time_stamp();
1360 // Since everything potentially moved, we will clear all remembered
1361 // sets, and clear all cards. Later we will rebuild remembered
1362 // sets. We will also reset the GC time stamps of the regions.
1363 clear_rsets_post_compaction();
1364 check_gc_time_stamps();
1365
1366 resize_if_necessary_after_full_collection();
1367
1368 // We should do this after we potentially resize the heap so
1369 // that all the COMMIT / UNCOMMIT events are generated before
1370 // the compaction events.
1371 print_hrm_post_compaction();
1372
1373 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1374 if (hot_card_cache->use_cache()) {
1375 hot_card_cache->reset_card_counts();
1376 hot_card_cache->reset_hot_cache();
1377 }
1378
1379 // Rebuild remembered sets of all regions.
1380 uint n_workers =
1381 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1382 workers()->active_workers(),
1383 Threads::number_of_non_daemon_threads());
1384 workers()->set_active_workers(n_workers);
1385
1386 ParRebuildRSTask rebuild_rs_task(this);
1387 workers()->run_task(&rebuild_rs_task);
1388
1389 // Rebuild the strong code root lists for each region
1390 rebuild_strong_code_roots();
1391
1392 if (true) { // FIXME
1393 MetaspaceGC::compute_new_size();
1394 }
1395
1396 #ifdef TRACESPINNING
1397 ParallelTaskTerminator::print_termination_counts();
1398 #endif
1399
1400 // Discard all rset updates
1401 JavaThread::dirty_card_queue_set().abandon_logs();
1402 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1403
1404 _young_list->reset_sampled_info();
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(g1_policy()->collection_set() == NULL, "must be");
1432 g1_policy()->start_incremental_cset_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 trace_heap_after_gc(gc_tracer);
1452
1453 post_full_gc_dump(gc_timer);
1454 }
1455
1456 gc_timer->register_gc_end();
1457 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1458 }
1459
1460 return true;
1461 }
1462
1463 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1464 // Currently, there is no facility in the do_full_collection(bool) API to notify
1465 // the caller that the collection did not succeed (e.g., because it was locked
1466 // out by the GC locker). So, right now, we'll ignore the return value.
1467 bool dummy = do_full_collection(true, /* explicit_gc */
1468 clear_all_soft_refs);
1469 }
1470
1471 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1472 // Include bytes that will be pre-allocated to support collections, as "used".
1473 const size_t used_after_gc = used();
1474 const size_t capacity_after_gc = capacity();
1475 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1476
1477 // This is enforced in arguments.cpp.
1478 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1479 "otherwise the code below doesn't make sense");
1480
1481 // We don't have floating point command-line arguments
1482 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1483 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1484 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1485 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1486
1487 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1488 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1489
1490 // We have to be careful here as these two calculations can overflow
1491 // 32-bit size_t's.
1492 double used_after_gc_d = (double) used_after_gc;
1493 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1494 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1495
1496 // Let's make sure that they are both under the max heap size, which
1497 // by default will make them fit into a size_t.
1498 double desired_capacity_upper_bound = (double) max_heap_size;
1499 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1500 desired_capacity_upper_bound);
1501 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1502 desired_capacity_upper_bound);
1503
1504 // We can now safely turn them into size_t's.
1505 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1506 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1507
1508 // This assert only makes sense here, before we adjust them
1509 // with respect to the min and max heap size.
1510 assert(minimum_desired_capacity <= maximum_desired_capacity,
1511 "minimum_desired_capacity = " SIZE_FORMAT ", "
1512 "maximum_desired_capacity = " SIZE_FORMAT,
1513 minimum_desired_capacity, maximum_desired_capacity);
1514
1515 // Should not be greater than the heap max size. No need to adjust
1516 // it with respect to the heap min size as it's a lower bound (i.e.,
1517 // we'll try to make the capacity larger than it, not smaller).
1518 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1519 // Should not be less than the heap min size. No need to adjust it
1520 // with respect to the heap max size as it's an upper bound (i.e.,
1521 // we'll try to make the capacity smaller than it, not greater).
1522 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1523
1524 if (capacity_after_gc < minimum_desired_capacity) {
1525 // Don't expand unless it's significant
1526 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1527
1528 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1529 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1530 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1531
1532 expand(expand_bytes);
1533
1534 // No expansion, now see if we want to shrink
1535 } else if (capacity_after_gc > maximum_desired_capacity) {
1536 // Capacity too large, compute shrinking size
1537 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1538
1539 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1540 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1541 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1542
1543 shrink(shrink_bytes);
1544 }
1545 }
1546
1547 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1548 AllocationContext_t context,
1549 bool do_gc,
1550 bool clear_all_soft_refs,
1551 bool expect_null_mutator_alloc_region,
1552 bool* gc_succeeded) {
1553 *gc_succeeded = true;
1554 // Let's attempt the allocation first.
1555 HeapWord* result =
1556 attempt_allocation_at_safepoint(word_size,
1557 context,
1558 expect_null_mutator_alloc_region);
1559 if (result != NULL) {
1560 assert(*gc_succeeded, "sanity");
1561 return result;
1562 }
1563
1564 // In a G1 heap, we're supposed to keep allocation from failing by
1565 // incremental pauses. Therefore, at least for now, we'll favor
1566 // expansion over collection. (This might change in the future if we can
1567 // do something smarter than full collection to satisfy a failed alloc.)
1568 result = expand_and_allocate(word_size, context);
1569 if (result != NULL) {
1570 assert(*gc_succeeded, "sanity");
1571 return result;
1572 }
1573
1574 if (do_gc) {
1575 // Expansion didn't work, we'll try to do a Full GC.
1576 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1577 clear_all_soft_refs);
1578 }
1579
1580 return NULL;
1581 }
1582
1583 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1584 AllocationContext_t context,
1585 bool* succeeded) {
1586 assert_at_safepoint(true /* should_be_vm_thread */);
1587
1588 // Attempts to allocate followed by Full GC.
1589 HeapWord* result =
1590 satisfy_failed_allocation_helper(word_size,
1591 context,
1592 true, /* do_gc */
1593 false, /* clear_all_soft_refs */
1594 false, /* expect_null_mutator_alloc_region */
1595 succeeded);
1596
1597 if (result != NULL || !*succeeded) {
1598 return result;
1599 }
1600
1601 // Attempts to allocate followed by Full GC that will collect all soft references.
1602 result = satisfy_failed_allocation_helper(word_size,
1603 context,
1604 true, /* do_gc */
1605 true, /* clear_all_soft_refs */
1606 true, /* expect_null_mutator_alloc_region */
1607 succeeded);
1608
1609 if (result != NULL || !*succeeded) {
1610 return result;
1611 }
1612
1613 // Attempts to allocate, no GC
1614 result = satisfy_failed_allocation_helper(word_size,
1615 context,
1616 false, /* do_gc */
1617 false, /* clear_all_soft_refs */
1618 true, /* expect_null_mutator_alloc_region */
1619 succeeded);
1620
1621 if (result != NULL) {
1622 assert(*succeeded, "sanity");
1623 return result;
1624 }
1625
1626 assert(!collector_policy()->should_clear_all_soft_refs(),
1627 "Flag should have been handled and cleared prior to this point");
1628
1629 // What else? We might try synchronous finalization later. If the total
1630 // space available is large enough for the allocation, then a more
1631 // complete compaction phase than we've tried so far might be
1632 // appropriate.
1633 assert(*succeeded, "sanity");
1634 return NULL;
1635 }
1636
1637 // Attempting to expand the heap sufficiently
1638 // to support an allocation of the given "word_size". If
1639 // successful, perform the allocation and return the address of the
1640 // allocated block, or else "NULL".
1641
1642 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1643 assert_at_safepoint(true /* should_be_vm_thread */);
1644
1645 _verifier->verify_region_sets_optional();
1646
1647 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1648 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1649 word_size * HeapWordSize);
1650
1651
1652 if (expand(expand_bytes)) {
1653 _hrm.verify_optional();
1654 _verifier->verify_region_sets_optional();
1655 return attempt_allocation_at_safepoint(word_size,
1656 context,
1657 false /* expect_null_mutator_alloc_region */);
1658 }
1659 return NULL;
1660 }
1661
1662 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1663 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1664 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1665 HeapRegion::GrainBytes);
1666
1667 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1668 expand_bytes, aligned_expand_bytes);
1669
1670 if (is_maximal_no_gc()) {
1671 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1672 return false;
1673 }
1674
1675 double expand_heap_start_time_sec = os::elapsedTime();
1676 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1677 assert(regions_to_expand > 0, "Must expand by at least one region");
1678
1679 uint expanded_by = _hrm.expand_by(regions_to_expand);
1680 if (expand_time_ms != NULL) {
1681 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1682 }
1683
1684 if (expanded_by > 0) {
1685 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1686 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1687 g1_policy()->record_new_heap_size(num_regions());
1688 } else {
1689 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1690
1691 // The expansion of the virtual storage space was unsuccessful.
1692 // Let's see if it was because we ran out of swap.
1693 if (G1ExitOnExpansionFailure &&
1694 _hrm.available() >= regions_to_expand) {
1695 // We had head room...
1696 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1697 }
1698 }
1699 return regions_to_expand > 0;
1700 }
1701
1702 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1703 size_t aligned_shrink_bytes =
1704 ReservedSpace::page_align_size_down(shrink_bytes);
1705 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1706 HeapRegion::GrainBytes);
1707 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1708
1709 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1710 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1711
1712
1713 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",
1714 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1715 if (num_regions_removed > 0) {
1716 g1_policy()->record_new_heap_size(num_regions());
1717 } else {
1718 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1719 }
1720 }
1721
1722 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1723 _verifier->verify_region_sets_optional();
1724
1725 // We should only reach here at the end of a Full GC which means we
1726 // should not not be holding to any GC alloc regions. The method
1727 // below will make sure of that and do any remaining clean up.
1728 _allocator->abandon_gc_alloc_regions();
1729
1730 // Instead of tearing down / rebuilding the free lists here, we
1731 // could instead use the remove_all_pending() method on free_list to
1732 // remove only the ones that we need to remove.
1733 tear_down_region_sets(true /* free_list_only */);
1734 shrink_helper(shrink_bytes);
1735 rebuild_region_sets(true /* free_list_only */);
1736
1737 _hrm.verify_optional();
1738 _verifier->verify_region_sets_optional();
1739 }
1740
1741 // Public methods.
1742
1743 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1744 CollectedHeap(),
1745 _g1_policy(policy_),
1746 _dirty_card_queue_set(false),
1747 _is_alive_closure_cm(this),
1748 _is_alive_closure_stw(this),
1749 _ref_processor_cm(NULL),
1750 _ref_processor_stw(NULL),
1751 _bot(NULL),
1752 _cg1r(NULL),
1753 _g1mm(NULL),
1754 _refine_cte_cl(NULL),
1755 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1756 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1757 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1758 _humongous_reclaim_candidates(),
1759 _has_humongous_reclaim_candidates(false),
1760 _archive_allocator(NULL),
1761 _free_regions_coming(false),
1762 _young_list(new YoungList(this)),
1763 _gc_time_stamp(0),
1764 _summary_bytes_used(0),
1765 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1766 _old_evac_stats(OldPLABSize, PLABWeight),
1767 _expand_heap_after_alloc_failure(true),
1768 _old_marking_cycles_started(0),
1769 _old_marking_cycles_completed(0),
1770 _heap_summary_sent(false),
1771 _in_cset_fast_test(),
1772 _dirty_cards_region_list(NULL),
1773 _worker_cset_start_region(NULL),
1774 _worker_cset_start_region_time_stamp(NULL),
1775 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1776 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1777 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1778 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1779
1780 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1781 /* are_GC_task_threads */true,
1782 /* are_ConcurrentGC_threads */false);
1783 _workers->initialize_workers();
1784 _verifier = new G1HeapVerifier(this);
1785
1786 _allocator = G1Allocator::create_allocator(this);
1787 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1788
1789 // Override the default _filler_array_max_size so that no humongous filler
1790 // objects are created.
1791 _filler_array_max_size = _humongous_object_threshold_in_words;
1792
1793 uint n_queues = ParallelGCThreads;
1794 _task_queues = new RefToScanQueueSet(n_queues);
1795
1796 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1797 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1798 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1799
1800 for (uint i = 0; i < n_queues; i++) {
1801 RefToScanQueue* q = new RefToScanQueue();
1802 q->initialize();
1803 _task_queues->register_queue(i, q);
1804 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1805 }
1806 clear_cset_start_regions();
1807
1808 // Initialize the G1EvacuationFailureALot counters and flags.
1809 NOT_PRODUCT(reset_evacuation_should_fail();)
1810
1811 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1812 }
1813
1814 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1815 size_t size,
1816 size_t translation_factor) {
1817 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1818 // Allocate a new reserved space, preferring to use large pages.
1819 ReservedSpace rs(size, preferred_page_size);
1820 G1RegionToSpaceMapper* result =
1821 G1RegionToSpaceMapper::create_mapper(rs,
1822 size,
1823 rs.alignment(),
1824 HeapRegion::GrainBytes,
1825 translation_factor,
1826 mtGC);
1827 if (TracePageSizes) {
1828 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1829 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1830 }
1831 return result;
1832 }
1833
1834 jint G1CollectedHeap::initialize() {
1835 CollectedHeap::pre_initialize();
1836 os::enable_vtime();
1837
1838 // Necessary to satisfy locking discipline assertions.
1839
1840 MutexLocker x(Heap_lock);
1841
1842 // While there are no constraints in the GC code that HeapWordSize
1843 // be any particular value, there are multiple other areas in the
1844 // system which believe this to be true (e.g. oop->object_size in some
1845 // cases incorrectly returns the size in wordSize units rather than
1846 // HeapWordSize).
1847 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1848
1849 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1850 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1851 size_t heap_alignment = collector_policy()->heap_alignment();
1852
1853 // Ensure that the sizes are properly aligned.
1854 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1855 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1856 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1857
1858 _refine_cte_cl = new RefineCardTableEntryClosure();
1859
1860 jint ecode = JNI_OK;
1861 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1862 if (_cg1r == NULL) {
1863 return ecode;
1864 }
1865
1866 // Reserve the maximum.
1867
1868 // When compressed oops are enabled, the preferred heap base
1869 // is calculated by subtracting the requested size from the
1870 // 32Gb boundary and using the result as the base address for
1871 // heap reservation. If the requested size is not aligned to
1872 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1873 // into the ReservedHeapSpace constructor) then the actual
1874 // base of the reserved heap may end up differing from the
1875 // address that was requested (i.e. the preferred heap base).
1876 // If this happens then we could end up using a non-optimal
1877 // compressed oops mode.
1878
1879 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1880 heap_alignment);
1881
1882 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1883
1884 // Create the barrier set for the entire reserved region.
1885 G1SATBCardTableLoggingModRefBS* bs
1886 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1887 bs->initialize();
1888 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1889 set_barrier_set(bs);
1890
1891 // Also create a G1 rem set.
1892 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1893
1894 // Carve out the G1 part of the heap.
1895 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1896 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1897 G1RegionToSpaceMapper* heap_storage =
1898 G1RegionToSpaceMapper::create_mapper(g1_rs,
1899 g1_rs.size(),
1900 page_size,
1901 HeapRegion::GrainBytes,
1902 1,
1903 mtJavaHeap);
1904 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1905 max_byte_size, page_size,
1906 heap_rs.base(),
1907 heap_rs.size());
1908 heap_storage->set_mapping_changed_listener(&_listener);
1909
1910 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1911 G1RegionToSpaceMapper* bot_storage =
1912 create_aux_memory_mapper("Block offset table",
1913 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1914 G1BlockOffsetTable::heap_map_factor());
1915
1916 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1917 G1RegionToSpaceMapper* cardtable_storage =
1918 create_aux_memory_mapper("Card table",
1919 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1920 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1921
1922 G1RegionToSpaceMapper* card_counts_storage =
1923 create_aux_memory_mapper("Card counts table",
1924 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1925 G1CardCounts::heap_map_factor());
1926
1927 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1928 G1RegionToSpaceMapper* prev_bitmap_storage =
1929 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1930 G1RegionToSpaceMapper* next_bitmap_storage =
1931 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1932
1933 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1934 g1_barrier_set()->initialize(cardtable_storage);
1935 // Do later initialization work for concurrent refinement.
1936 _cg1r->init(card_counts_storage);
1937
1938 // 6843694 - ensure that the maximum region index can fit
1939 // in the remembered set structures.
1940 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1941 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1942
1943 G1RemSet::initialize(max_regions());
1944
1945 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1946 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1947 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1948 "too many cards per region");
1949
1950 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1951
1952 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1953
1954 {
1955 HeapWord* start = _hrm.reserved().start();
1956 HeapWord* end = _hrm.reserved().end();
1957 size_t granularity = HeapRegion::GrainBytes;
1958
1959 _in_cset_fast_test.initialize(start, end, granularity);
1960 _humongous_reclaim_candidates.initialize(start, end, granularity);
1961 }
1962
1963 // Create the G1ConcurrentMark data structure and thread.
1964 // (Must do this late, so that "max_regions" is defined.)
1965 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1966 if (_cm == NULL || !_cm->completed_initialization()) {
1967 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1968 return JNI_ENOMEM;
1969 }
1970 _cmThread = _cm->cmThread();
1971
1972 // Now expand into the initial heap size.
1973 if (!expand(init_byte_size)) {
1974 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1975 return JNI_ENOMEM;
1976 }
1977
1978 // Perform any initialization actions delegated to the policy.
1979 g1_policy()->init();
1980
1981 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1982 SATB_Q_FL_lock,
1983 G1SATBProcessCompletedThreshold,
1984 Shared_SATB_Q_lock);
1985
1986 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1987 DirtyCardQ_CBL_mon,
1988 DirtyCardQ_FL_lock,
1989 concurrent_g1_refine()->yellow_zone(),
1990 concurrent_g1_refine()->red_zone(),
1991 Shared_DirtyCardQ_lock,
1992 NULL, // fl_owner
1993 true); // init_free_ids
1994
1995 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1996 DirtyCardQ_CBL_mon,
1997 DirtyCardQ_FL_lock,
1998 -1, // never trigger processing
1999 -1, // no limit on length
2000 Shared_DirtyCardQ_lock,
2001 &JavaThread::dirty_card_queue_set());
2002
2003 // Here we allocate the dummy HeapRegion that is required by the
2004 // G1AllocRegion class.
2005 HeapRegion* dummy_region = _hrm.get_dummy_region();
2006
2007 // We'll re-use the same region whether the alloc region will
2008 // require BOT updates or not and, if it doesn't, then a non-young
2009 // region will complain that it cannot support allocations without
2010 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2011 dummy_region->set_eden();
2012 // Make sure it's full.
2013 dummy_region->set_top(dummy_region->end());
2014 G1AllocRegion::setup(this, dummy_region);
2015
2016 _allocator->init_mutator_alloc_region();
2017
2018 // Do create of the monitoring and management support so that
2019 // values in the heap have been properly initialized.
2020 _g1mm = new G1MonitoringSupport(this);
2021
2022 G1StringDedup::initialize();
2023
2024 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2025 for (uint i = 0; i < ParallelGCThreads; i++) {
2026 new (&_preserved_objs[i]) OopAndMarkOopStack();
2027 }
2028
2029 return JNI_OK;
2030 }
2031
2032 void G1CollectedHeap::stop() {
2033 // Stop all concurrent threads. We do this to make sure these threads
2034 // do not continue to execute and access resources (e.g. logging)
2035 // that are destroyed during shutdown.
2036 _cg1r->stop();
2037 _cmThread->stop();
2038 if (G1StringDedup::is_enabled()) {
2039 G1StringDedup::stop();
2040 }
2041 }
2042
2043 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2044 return HeapRegion::max_region_size();
2045 }
2046
2047 void G1CollectedHeap::post_initialize() {
2048 CollectedHeap::post_initialize();
2049 ref_processing_init();
2050 }
2051
2052 void G1CollectedHeap::ref_processing_init() {
2053 // Reference processing in G1 currently works as follows:
2054 //
2055 // * There are two reference processor instances. One is
2056 // used to record and process discovered references
2057 // during concurrent marking; the other is used to
2058 // record and process references during STW pauses
2059 // (both full and incremental).
2060 // * Both ref processors need to 'span' the entire heap as
2061 // the regions in the collection set may be dotted around.
2062 //
2063 // * For the concurrent marking ref processor:
2064 // * Reference discovery is enabled at initial marking.
2065 // * Reference discovery is disabled and the discovered
2066 // references processed etc during remarking.
2067 // * Reference discovery is MT (see below).
2068 // * Reference discovery requires a barrier (see below).
2069 // * Reference processing may or may not be MT
2070 // (depending on the value of ParallelRefProcEnabled
2071 // and ParallelGCThreads).
2072 // * A full GC disables reference discovery by the CM
2073 // ref processor and abandons any entries on it's
2074 // discovered lists.
2075 //
2076 // * For the STW processor:
2077 // * Non MT discovery is enabled at the start of a full GC.
2078 // * Processing and enqueueing during a full GC is non-MT.
2079 // * During a full GC, references are processed after marking.
2080 //
2081 // * Discovery (may or may not be MT) is enabled at the start
2082 // of an incremental evacuation pause.
2083 // * References are processed near the end of a STW evacuation pause.
2084 // * For both types of GC:
2085 // * Discovery is atomic - i.e. not concurrent.
2086 // * Reference discovery will not need a barrier.
2087
2088 MemRegion mr = reserved_region();
2089
2090 // Concurrent Mark ref processor
2091 _ref_processor_cm =
2092 new ReferenceProcessor(mr, // span
2093 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2094 // mt processing
2095 ParallelGCThreads,
2096 // degree of mt processing
2097 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2098 // mt discovery
2099 MAX2(ParallelGCThreads, ConcGCThreads),
2100 // degree of mt discovery
2101 false,
2102 // Reference discovery is not atomic
2103 &_is_alive_closure_cm);
2104 // is alive closure
2105 // (for efficiency/performance)
2106
2107 // STW ref processor
2108 _ref_processor_stw =
2109 new ReferenceProcessor(mr, // span
2110 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2111 // mt processing
2112 ParallelGCThreads,
2113 // degree of mt processing
2114 (ParallelGCThreads > 1),
2115 // mt discovery
2116 ParallelGCThreads,
2117 // degree of mt discovery
2118 true,
2119 // Reference discovery is atomic
2120 &_is_alive_closure_stw);
2121 // is alive closure
2122 // (for efficiency/performance)
2123 }
2124
2125 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2126 return g1_policy();
2127 }
2128
2129 size_t G1CollectedHeap::capacity() const {
2130 return _hrm.length() * HeapRegion::GrainBytes;
2131 }
2132
2133 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2134 hr->reset_gc_time_stamp();
2135 }
2136
2137 #ifndef PRODUCT
2138
2139 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2140 private:
2141 unsigned _gc_time_stamp;
2142 bool _failures;
2143
2144 public:
2145 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2146 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2147
2148 virtual bool doHeapRegion(HeapRegion* hr) {
2149 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2150 if (_gc_time_stamp != region_gc_time_stamp) {
2151 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2152 region_gc_time_stamp, _gc_time_stamp);
2153 _failures = true;
2154 }
2155 return false;
2156 }
2157
2158 bool failures() { return _failures; }
2159 };
2160
2161 void G1CollectedHeap::check_gc_time_stamps() {
2162 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2163 heap_region_iterate(&cl);
2164 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2165 }
2166 #endif // PRODUCT
2167
2168 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2169 _cg1r->hot_card_cache()->drain(cl, worker_i);
2170 }
2171
2172 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2173 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2174 size_t n_completed_buffers = 0;
2175 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2176 n_completed_buffers++;
2177 }
2178 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2179 dcqs.clear_n_completed_buffers();
2180 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2181 }
2182
2183 // Computes the sum of the storage used by the various regions.
2184 size_t G1CollectedHeap::used() const {
2185 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2186 if (_archive_allocator != NULL) {
2187 result += _archive_allocator->used();
2188 }
2189 return result;
2190 }
2191
2192 size_t G1CollectedHeap::used_unlocked() const {
2193 return _summary_bytes_used;
2194 }
2195
2196 class SumUsedClosure: public HeapRegionClosure {
2197 size_t _used;
2198 public:
2199 SumUsedClosure() : _used(0) {}
2200 bool doHeapRegion(HeapRegion* r) {
2201 _used += r->used();
2202 return false;
2203 }
2204 size_t result() { return _used; }
2205 };
2206
2207 size_t G1CollectedHeap::recalculate_used() const {
2208 double recalculate_used_start = os::elapsedTime();
2209
2210 SumUsedClosure blk;
2211 heap_region_iterate(&blk);
2212
2213 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2214 return blk.result();
2215 }
2216
2217 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2218 switch (cause) {
2219 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2220 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2221 case GCCause::_update_allocation_context_stats_inc: return true;
2222 case GCCause::_wb_conc_mark: return true;
2223 default : return false;
2224 }
2225 }
2226
2227 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2228 switch (cause) {
2229 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2230 case GCCause::_g1_humongous_allocation: return true;
2231 default: return is_user_requested_concurrent_full_gc(cause);
2232 }
2233 }
2234
2235 #ifndef PRODUCT
2236 void G1CollectedHeap::allocate_dummy_regions() {
2237 // Let's fill up most of the region
2238 size_t word_size = HeapRegion::GrainWords - 1024;
2239 // And as a result the region we'll allocate will be humongous.
2240 guarantee(is_humongous(word_size), "sanity");
2241
2242 // _filler_array_max_size is set to humongous object threshold
2243 // but temporarily change it to use CollectedHeap::fill_with_object().
2244 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2245
2246 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2247 // Let's use the existing mechanism for the allocation
2248 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2249 AllocationContext::system());
2250 if (dummy_obj != NULL) {
2251 MemRegion mr(dummy_obj, word_size);
2252 CollectedHeap::fill_with_object(mr);
2253 } else {
2254 // If we can't allocate once, we probably cannot allocate
2255 // again. Let's get out of the loop.
2256 break;
2257 }
2258 }
2259 }
2260 #endif // !PRODUCT
2261
2262 void G1CollectedHeap::increment_old_marking_cycles_started() {
2263 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2264 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2265 "Wrong marking cycle count (started: %d, completed: %d)",
2266 _old_marking_cycles_started, _old_marking_cycles_completed);
2267
2268 _old_marking_cycles_started++;
2269 }
2270
2271 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2272 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2273
2274 // We assume that if concurrent == true, then the caller is a
2275 // concurrent thread that was joined the Suspendible Thread
2276 // Set. If there's ever a cheap way to check this, we should add an
2277 // assert here.
2278
2279 // Given that this method is called at the end of a Full GC or of a
2280 // concurrent cycle, and those can be nested (i.e., a Full GC can
2281 // interrupt a concurrent cycle), the number of full collections
2282 // completed should be either one (in the case where there was no
2283 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2284 // behind the number of full collections started.
2285
2286 // This is the case for the inner caller, i.e. a Full GC.
2287 assert(concurrent ||
2288 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2289 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2290 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2291 "is inconsistent with _old_marking_cycles_completed = %u",
2292 _old_marking_cycles_started, _old_marking_cycles_completed);
2293
2294 // This is the case for the outer caller, i.e. the concurrent cycle.
2295 assert(!concurrent ||
2296 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2297 "for outer caller (concurrent cycle): "
2298 "_old_marking_cycles_started = %u "
2299 "is inconsistent with _old_marking_cycles_completed = %u",
2300 _old_marking_cycles_started, _old_marking_cycles_completed);
2301
2302 _old_marking_cycles_completed += 1;
2303
2304 // We need to clear the "in_progress" flag in the CM thread before
2305 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2306 // is set) so that if a waiter requests another System.gc() it doesn't
2307 // incorrectly see that a marking cycle is still in progress.
2308 if (concurrent) {
2309 _cmThread->set_idle();
2310 }
2311
2312 // This notify_all() will ensure that a thread that called
2313 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2314 // and it's waiting for a full GC to finish will be woken up. It is
2315 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2316 FullGCCount_lock->notify_all();
2317 }
2318
2319 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2320 GCIdMarkAndRestore conc_gc_id_mark;
2321 collector_state()->set_concurrent_cycle_started(true);
2322 _gc_timer_cm->register_gc_start(start_time);
2323
2324 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2325 trace_heap_before_gc(_gc_tracer_cm);
2326 _cmThread->set_gc_id(GCId::current());
2327 }
2328
2329 void G1CollectedHeap::register_concurrent_cycle_end() {
2330 if (collector_state()->concurrent_cycle_started()) {
2331 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2332 if (_cm->has_aborted()) {
2333 _gc_tracer_cm->report_concurrent_mode_failure();
2334 }
2335
2336 _gc_timer_cm->register_gc_end();
2337 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2338
2339 // Clear state variables to prepare for the next concurrent cycle.
2340 collector_state()->set_concurrent_cycle_started(false);
2341 _heap_summary_sent = false;
2342 }
2343 }
2344
2345 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2346 if (collector_state()->concurrent_cycle_started()) {
2347 // This function can be called when:
2348 // the cleanup pause is run
2349 // the concurrent cycle is aborted before the cleanup pause.
2350 // the concurrent cycle is aborted after the cleanup pause,
2351 // but before the concurrent cycle end has been registered.
2352 // Make sure that we only send the heap information once.
2353 if (!_heap_summary_sent) {
2354 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2355 trace_heap_after_gc(_gc_tracer_cm);
2356 _heap_summary_sent = true;
2357 }
2358 }
2359 }
2360
2361 void G1CollectedHeap::collect(GCCause::Cause cause) {
2362 assert_heap_not_locked();
2363
2364 uint gc_count_before;
2365 uint old_marking_count_before;
2366 uint full_gc_count_before;
2367 bool retry_gc;
2368
2369 do {
2370 retry_gc = false;
2371
2372 {
2373 MutexLocker ml(Heap_lock);
2374
2375 // Read the GC count while holding the Heap_lock
2376 gc_count_before = total_collections();
2377 full_gc_count_before = total_full_collections();
2378 old_marking_count_before = _old_marking_cycles_started;
2379 }
2380
2381 if (should_do_concurrent_full_gc(cause)) {
2382 // Schedule an initial-mark evacuation pause that will start a
2383 // concurrent cycle. We're setting word_size to 0 which means that
2384 // we are not requesting a post-GC allocation.
2385 VM_G1IncCollectionPause op(gc_count_before,
2386 0, /* word_size */
2387 true, /* should_initiate_conc_mark */
2388 g1_policy()->max_pause_time_ms(),
2389 cause);
2390 op.set_allocation_context(AllocationContext::current());
2391
2392 VMThread::execute(&op);
2393 if (!op.pause_succeeded()) {
2394 if (old_marking_count_before == _old_marking_cycles_started) {
2395 retry_gc = op.should_retry_gc();
2396 } else {
2397 // A Full GC happened while we were trying to schedule the
2398 // initial-mark GC. No point in starting a new cycle given
2399 // that the whole heap was collected anyway.
2400 }
2401
2402 if (retry_gc) {
2403 if (GCLocker::is_active_and_needs_gc()) {
2404 GCLocker::stall_until_clear();
2405 }
2406 }
2407 }
2408 } else {
2409 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2410 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2411
2412 // Schedule a standard evacuation pause. We're setting word_size
2413 // to 0 which means that we are not requesting a post-GC allocation.
2414 VM_G1IncCollectionPause op(gc_count_before,
2415 0, /* word_size */
2416 false, /* should_initiate_conc_mark */
2417 g1_policy()->max_pause_time_ms(),
2418 cause);
2419 VMThread::execute(&op);
2420 } else {
2421 // Schedule a Full GC.
2422 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2423 VMThread::execute(&op);
2424 }
2425 }
2426 } while (retry_gc);
2427 }
2428
2429 bool G1CollectedHeap::is_in(const void* p) const {
2430 if (_hrm.reserved().contains(p)) {
2431 // Given that we know that p is in the reserved space,
2432 // heap_region_containing() should successfully
2433 // return the containing region.
2434 HeapRegion* hr = heap_region_containing(p);
2435 return hr->is_in(p);
2436 } else {
2437 return false;
2438 }
2439 }
2440
2441 #ifdef ASSERT
2442 bool G1CollectedHeap::is_in_exact(const void* p) const {
2443 bool contains = reserved_region().contains(p);
2444 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2445 if (contains && available) {
2446 return true;
2447 } else {
2448 return false;
2449 }
2450 }
2451 #endif
2452
2453 bool G1CollectedHeap::obj_in_cs(oop obj) {
2454 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2455 return r != NULL && r->in_collection_set();
2456 }
2457
2458 // Iteration functions.
2459
2460 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2461
2462 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2463 ExtendedOopClosure* _cl;
2464 public:
2465 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2466 bool doHeapRegion(HeapRegion* r) {
2467 if (!r->is_continues_humongous()) {
2468 r->oop_iterate(_cl);
2469 }
2470 return false;
2471 }
2472 };
2473
2474 // Iterates an ObjectClosure over all objects within a HeapRegion.
2475
2476 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2477 ObjectClosure* _cl;
2478 public:
2479 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2480 bool doHeapRegion(HeapRegion* r) {
2481 if (!r->is_continues_humongous()) {
2482 r->object_iterate(_cl);
2483 }
2484 return false;
2485 }
2486 };
2487
2488 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2489 IterateObjectClosureRegionClosure blk(cl);
2490 heap_region_iterate(&blk);
2491 }
2492
2493 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2494 _hrm.iterate(cl);
2495 }
2496
2497 void
2498 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2499 uint worker_id,
2500 HeapRegionClaimer *hrclaimer,
2501 bool concurrent) const {
2502 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2503 }
2504
2505 // Clear the cached CSet starting regions and (more importantly)
2506 // the time stamps. Called when we reset the GC time stamp.
2507 void G1CollectedHeap::clear_cset_start_regions() {
2508 assert(_worker_cset_start_region != NULL, "sanity");
2509 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2510
2511 for (uint i = 0; i < ParallelGCThreads; i++) {
2512 _worker_cset_start_region[i] = NULL;
2513 _worker_cset_start_region_time_stamp[i] = 0;
2514 }
2515 }
2516
2517 // Given the id of a worker, obtain or calculate a suitable
2518 // starting region for iterating over the current collection set.
2519 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2520 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2521
2522 HeapRegion* result = NULL;
2523 unsigned gc_time_stamp = get_gc_time_stamp();
2524
2525 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2526 // Cached starting region for current worker was set
2527 // during the current pause - so it's valid.
2528 // Note: the cached starting heap region may be NULL
2529 // (when the collection set is empty).
2530 result = _worker_cset_start_region[worker_i];
2531 assert(result == NULL || result->in_collection_set(), "sanity");
2532 return result;
2533 }
2534
2535 // The cached entry was not valid so let's calculate
2536 // a suitable starting heap region for this worker.
2537
2538 // We want the parallel threads to start their collection
2539 // set iteration at different collection set regions to
2540 // avoid contention.
2541 // If we have:
2542 // n collection set regions
2543 // p threads
2544 // Then thread t will start at region floor ((t * n) / p)
2545
2546 result = g1_policy()->collection_set();
2547 uint cs_size = g1_policy()->cset_region_length();
2548 uint active_workers = workers()->active_workers();
2549
2550 uint end_ind = (cs_size * worker_i) / active_workers;
2551 uint start_ind = 0;
2552
2553 if (worker_i > 0 &&
2554 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2555 // Previous workers starting region is valid
2556 // so let's iterate from there
2557 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2558 OrderAccess::loadload();
2559 result = _worker_cset_start_region[worker_i - 1];
2560 }
2561
2562 for (uint i = start_ind; i < end_ind; i++) {
2563 result = result->next_in_collection_set();
2564 }
2565
2566 // Note: the calculated starting heap region may be NULL
2567 // (when the collection set is empty).
2568 assert(result == NULL || result->in_collection_set(), "sanity");
2569 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2570 "should be updated only once per pause");
2571 _worker_cset_start_region[worker_i] = result;
2572 OrderAccess::storestore();
2573 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2574 return result;
2575 }
2576
2577 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2578 HeapRegion* r = g1_policy()->collection_set();
2579 while (r != NULL) {
2580 HeapRegion* next = r->next_in_collection_set();
2581 if (cl->doHeapRegion(r)) {
2582 cl->incomplete();
2583 return;
2584 }
2585 r = next;
2586 }
2587 }
2588
2589 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2590 HeapRegionClosure *cl) {
2591 if (r == NULL) {
2592 // The CSet is empty so there's nothing to do.
2593 return;
2594 }
2595
2596 assert(r->in_collection_set(),
2597 "Start region must be a member of the collection set.");
2598 HeapRegion* cur = r;
2599 while (cur != NULL) {
2600 HeapRegion* next = cur->next_in_collection_set();
2601 if (cl->doHeapRegion(cur) && false) {
2602 cl->incomplete();
2603 return;
2604 }
2605 cur = next;
2606 }
2607 cur = g1_policy()->collection_set();
2608 while (cur != r) {
2609 HeapRegion* next = cur->next_in_collection_set();
2610 if (cl->doHeapRegion(cur) && false) {
2611 cl->incomplete();
2612 return;
2613 }
2614 cur = next;
2615 }
2616 }
2617
2618 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2619 HeapRegion* result = _hrm.next_region_in_heap(from);
2620 while (result != NULL && result->is_pinned()) {
2621 result = _hrm.next_region_in_heap(result);
2622 }
2623 return result;
2624 }
2625
2626 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2627 HeapRegion* hr = heap_region_containing(addr);
2628 return hr->block_start(addr);
2629 }
2630
2631 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2632 HeapRegion* hr = heap_region_containing(addr);
2633 return hr->block_size(addr);
2634 }
2635
2636 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2637 HeapRegion* hr = heap_region_containing(addr);
2638 return hr->block_is_obj(addr);
2639 }
2640
2641 bool G1CollectedHeap::supports_tlab_allocation() const {
2642 return true;
2643 }
2644
2645 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2646 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2647 }
2648
2649 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2650 return young_list()->eden_used_bytes();
2651 }
2652
2653 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2654 // must be equal to the humongous object limit.
2655 size_t G1CollectedHeap::max_tlab_size() const {
2656 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2657 }
2658
2659 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2660 AllocationContext_t context = AllocationContext::current();
2661 return _allocator->unsafe_max_tlab_alloc(context);
2662 }
2663
2664 size_t G1CollectedHeap::max_capacity() const {
2665 return _hrm.reserved().byte_size();
2666 }
2667
2668 jlong G1CollectedHeap::millis_since_last_gc() {
2669 // assert(false, "NYI");
2670 return 0;
2671 }
2672
2673 void G1CollectedHeap::prepare_for_verify() {
2674 _verifier->prepare_for_verify();
2675 }
2676
2677 void G1CollectedHeap::verify(VerifyOption vo) {
2678 _verifier->verify(vo);
2679 }
2680
2681 class PrintRegionClosure: public HeapRegionClosure {
2682 outputStream* _st;
2683 public:
2684 PrintRegionClosure(outputStream* st) : _st(st) {}
2685 bool doHeapRegion(HeapRegion* r) {
2686 r->print_on(_st);
2687 return false;
2688 }
2689 };
2690
2691 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2692 const HeapRegion* hr,
2693 const VerifyOption vo) const {
2694 switch (vo) {
2695 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2696 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2697 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2698 default: ShouldNotReachHere();
2699 }
2700 return false; // keep some compilers happy
2701 }
2702
2703 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2704 const VerifyOption vo) const {
2705 switch (vo) {
2706 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2707 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2708 case VerifyOption_G1UseMarkWord: {
2709 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2710 return !obj->is_gc_marked() && !hr->is_archive();
2711 }
2712 default: ShouldNotReachHere();
2713 }
2714 return false; // keep some compilers happy
2715 }
2716
2717 void G1CollectedHeap::print_on(outputStream* st) const {
2718 st->print(" %-20s", "garbage-first heap");
2719 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2720 capacity()/K, used_unlocked()/K);
2721 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2722 p2i(_hrm.reserved().start()),
2723 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2724 p2i(_hrm.reserved().end()));
2725 st->cr();
2726 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2727 uint young_regions = _young_list->length();
2728 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2729 (size_t) young_regions * HeapRegion::GrainBytes / K);
2730 uint survivor_regions = g1_policy()->recorded_survivor_regions();
2731 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2732 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2733 st->cr();
2734 MetaspaceAux::print_on(st);
2735 }
2736
2737 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2738 print_on(st);
2739
2740 // Print the per-region information.
2741 st->cr();
2742 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2743 "HS=humongous(starts), HC=humongous(continues), "
2744 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2745 "AC=allocation context, "
2746 "TAMS=top-at-mark-start (previous, next)");
2747 PrintRegionClosure blk(st);
2748 heap_region_iterate(&blk);
2749 }
2750
2751 void G1CollectedHeap::print_on_error(outputStream* st) const {
2752 this->CollectedHeap::print_on_error(st);
2753
2754 if (_cm != NULL) {
2755 st->cr();
2756 _cm->print_on_error(st);
2757 }
2758 }
2759
2760 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2761 workers()->print_worker_threads_on(st);
2762 _cmThread->print_on(st);
2763 st->cr();
2764 _cm->print_worker_threads_on(st);
2765 _cg1r->print_worker_threads_on(st);
2766 if (G1StringDedup::is_enabled()) {
2767 G1StringDedup::print_worker_threads_on(st);
2768 }
2769 }
2770
2771 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2772 workers()->threads_do(tc);
2773 tc->do_thread(_cmThread);
2774 _cg1r->threads_do(tc);
2775 if (G1StringDedup::is_enabled()) {
2776 G1StringDedup::threads_do(tc);
2777 }
2778 }
2779
2780 void G1CollectedHeap::print_tracing_info() const {
2781 // We'll overload this to mean "trace GC pause statistics."
2782 if (TraceYoungGenTime || TraceOldGenTime) {
2783 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2784 // to that.
2785 g1_policy()->print_tracing_info();
2786 }
2787 g1_rem_set()->print_summary_info();
2788 concurrent_mark()->print_summary_info();
2789 g1_policy()->print_yg_surv_rate_info();
2790 }
2791
2792 #ifndef PRODUCT
2793 // Helpful for debugging RSet issues.
2794
2795 class PrintRSetsClosure : public HeapRegionClosure {
2796 private:
2797 const char* _msg;
2798 size_t _occupied_sum;
2799
2800 public:
2801 bool doHeapRegion(HeapRegion* r) {
2802 HeapRegionRemSet* hrrs = r->rem_set();
2803 size_t occupied = hrrs->occupied();
2804 _occupied_sum += occupied;
2805
2806 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2807 if (occupied == 0) {
2808 tty->print_cr(" RSet is empty");
2809 } else {
2810 hrrs->print();
2811 }
2812 tty->print_cr("----------");
2813 return false;
2814 }
2815
2816 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2817 tty->cr();
2818 tty->print_cr("========================================");
2819 tty->print_cr("%s", msg);
2820 tty->cr();
2821 }
2822
2823 ~PrintRSetsClosure() {
2824 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2825 tty->print_cr("========================================");
2826 tty->cr();
2827 }
2828 };
2829
2830 void G1CollectedHeap::print_cset_rsets() {
2831 PrintRSetsClosure cl("Printing CSet RSets");
2832 collection_set_iterate(&cl);
2833 }
2834
2835 void G1CollectedHeap::print_all_rsets() {
2836 PrintRSetsClosure cl("Printing All RSets");;
2837 heap_region_iterate(&cl);
2838 }
2839 #endif // PRODUCT
2840
2841 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2842 YoungList* young_list = heap()->young_list();
2843
2844 size_t eden_used_bytes = young_list->eden_used_bytes();
2845 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2846
2847 size_t eden_capacity_bytes =
2848 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2849
2850 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2851 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
2852 }
2853
2854 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2855 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2856 stats->unused(), stats->used(), stats->region_end_waste(),
2857 stats->regions_filled(), stats->direct_allocated(),
2858 stats->failure_used(), stats->failure_waste());
2859 }
2860
2861 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2862 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2863 gc_tracer->report_gc_heap_summary(when, heap_summary);
2864
2865 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2866 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2867 }
2868
2869
2870 G1CollectedHeap* G1CollectedHeap::heap() {
2871 CollectedHeap* heap = Universe::heap();
2872 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2873 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2874 return (G1CollectedHeap*)heap;
2875 }
2876
2877 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2878 // always_do_update_barrier = false;
2879 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2880 // Fill TLAB's and such
2881 accumulate_statistics_all_tlabs();
2882 ensure_parsability(true);
2883
2884 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2885 }
2886
2887 void G1CollectedHeap::gc_epilogue(bool full) {
2888 // we are at the end of the GC. Total collections has already been increased.
2889 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2890
2891 // FIXME: what is this about?
2892 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2893 // is set.
2894 #if defined(COMPILER2) || INCLUDE_JVMCI
2895 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2896 #endif
2897 // always_do_update_barrier = true;
2898
2899 resize_all_tlabs();
2900 allocation_context_stats().update(full);
2901
2902 // We have just completed a GC. Update the soft reference
2903 // policy with the new heap occupancy
2904 Universe::update_heap_info_at_gc();
2905 }
2906
2907 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2908 uint gc_count_before,
2909 bool* succeeded,
2910 GCCause::Cause gc_cause) {
2911 assert_heap_not_locked_and_not_at_safepoint();
2912 g1_policy()->record_stop_world_start();
2913 VM_G1IncCollectionPause op(gc_count_before,
2914 word_size,
2915 false, /* should_initiate_conc_mark */
2916 g1_policy()->max_pause_time_ms(),
2917 gc_cause);
2918
2919 op.set_allocation_context(AllocationContext::current());
2920 VMThread::execute(&op);
2921
2922 HeapWord* result = op.result();
2923 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2924 assert(result == NULL || ret_succeeded,
2925 "the result should be NULL if the VM did not succeed");
2926 *succeeded = ret_succeeded;
2927
2928 assert_heap_not_locked();
2929 return result;
2930 }
2931
2932 void
2933 G1CollectedHeap::doConcurrentMark() {
2934 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2935 if (!_cmThread->in_progress()) {
2936 _cmThread->set_started();
2937 CGC_lock->notify();
2938 }
2939 }
2940
2941 size_t G1CollectedHeap::pending_card_num() {
2942 size_t extra_cards = 0;
2943 JavaThread *curr = Threads::first();
2944 while (curr != NULL) {
2945 DirtyCardQueue& dcq = curr->dirty_card_queue();
2946 extra_cards += dcq.size();
2947 curr = curr->next();
2948 }
2949 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2950 size_t buffer_size = dcqs.buffer_size();
2951 size_t buffer_num = dcqs.completed_buffers_num();
2952
2953 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2954 // in bytes - not the number of 'entries'. We need to convert
2955 // into a number of cards.
2956 return (buffer_size * buffer_num + extra_cards) / oopSize;
2957 }
2958
2959 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2960 private:
2961 size_t _total_humongous;
2962 size_t _candidate_humongous;
2963
2964 DirtyCardQueue _dcq;
2965
2966 // We don't nominate objects with many remembered set entries, on
2967 // the assumption that such objects are likely still live.
2968 bool is_remset_small(HeapRegion* region) const {
2969 HeapRegionRemSet* const rset = region->rem_set();
2970 return G1EagerReclaimHumongousObjectsWithStaleRefs
2971 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2972 : rset->is_empty();
2973 }
2974
2975 bool is_typeArray_region(HeapRegion* region) const {
2976 return oop(region->bottom())->is_typeArray();
2977 }
2978
2979 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2980 assert(region->is_starts_humongous(), "Must start a humongous object");
2981
2982 // Candidate selection must satisfy the following constraints
2983 // while concurrent marking is in progress:
2984 //
2985 // * In order to maintain SATB invariants, an object must not be
2986 // reclaimed if it was allocated before the start of marking and
2987 // has not had its references scanned. Such an object must have
2988 // its references (including type metadata) scanned to ensure no
2989 // live objects are missed by the marking process. Objects
2990 // allocated after the start of concurrent marking don't need to
2991 // be scanned.
2992 //
2993 // * An object must not be reclaimed if it is on the concurrent
2994 // mark stack. Objects allocated after the start of concurrent
2995 // marking are never pushed on the mark stack.
2996 //
2997 // Nominating only objects allocated after the start of concurrent
2998 // marking is sufficient to meet both constraints. This may miss
2999 // some objects that satisfy the constraints, but the marking data
3000 // structures don't support efficiently performing the needed
3001 // additional tests or scrubbing of the mark stack.
3002 //
3003 // However, we presently only nominate is_typeArray() objects.
3004 // A humongous object containing references induces remembered
3005 // set entries on other regions. In order to reclaim such an
3006 // object, those remembered sets would need to be cleaned up.
3007 //
3008 // We also treat is_typeArray() objects specially, allowing them
3009 // to be reclaimed even if allocated before the start of
3010 // concurrent mark. For this we rely on mark stack insertion to
3011 // exclude is_typeArray() objects, preventing reclaiming an object
3012 // that is in the mark stack. We also rely on the metadata for
3013 // such objects to be built-in and so ensured to be kept live.
3014 // Frequent allocation and drop of large binary blobs is an
3015 // important use case for eager reclaim, and this special handling
3016 // may reduce needed headroom.
3017
3018 return is_typeArray_region(region) && is_remset_small(region);
3019 }
3020
3021 public:
3022 RegisterHumongousWithInCSetFastTestClosure()
3023 : _total_humongous(0),
3024 _candidate_humongous(0),
3025 _dcq(&JavaThread::dirty_card_queue_set()) {
3026 }
3027
3028 virtual bool doHeapRegion(HeapRegion* r) {
3029 if (!r->is_starts_humongous()) {
3030 return false;
3031 }
3032 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3033
3034 bool is_candidate = humongous_region_is_candidate(g1h, r);
3035 uint rindex = r->hrm_index();
3036 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3037 if (is_candidate) {
3038 _candidate_humongous++;
3039 g1h->register_humongous_region_with_cset(rindex);
3040 // Is_candidate already filters out humongous object with large remembered sets.
3041 // If we have a humongous object with a few remembered sets, we simply flush these
3042 // remembered set entries into the DCQS. That will result in automatic
3043 // re-evaluation of their remembered set entries during the following evacuation
3044 // phase.
3045 if (!r->rem_set()->is_empty()) {
3046 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3047 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3048 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3049 HeapRegionRemSetIterator hrrs(r->rem_set());
3050 size_t card_index;
3051 while (hrrs.has_next(card_index)) {
3052 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3053 // The remembered set might contain references to already freed
3054 // regions. Filter out such entries to avoid failing card table
3055 // verification.
3056 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3057 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3058 *card_ptr = CardTableModRefBS::dirty_card_val();
3059 _dcq.enqueue(card_ptr);
3060 }
3061 }
3062 }
3063 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3064 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3065 hrrs.n_yielded(), r->rem_set()->occupied());
3066 r->rem_set()->clear_locked();
3067 }
3068 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3069 }
3070 _total_humongous++;
3071
3072 return false;
3073 }
3074
3075 size_t total_humongous() const { return _total_humongous; }
3076 size_t candidate_humongous() const { return _candidate_humongous; }
3077
3078 void flush_rem_set_entries() { _dcq.flush(); }
3079 };
3080
3081 void G1CollectedHeap::register_humongous_regions_with_cset() {
3082 if (!G1EagerReclaimHumongousObjects) {
3083 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3084 return;
3085 }
3086 double time = os::elapsed_counter();
3087
3088 // Collect reclaim candidate information and register candidates with cset.
3089 RegisterHumongousWithInCSetFastTestClosure cl;
3090 heap_region_iterate(&cl);
3091
3092 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3093 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3094 cl.total_humongous(),
3095 cl.candidate_humongous());
3096 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3097
3098 // Finally flush all remembered set entries to re-check into the global DCQS.
3099 cl.flush_rem_set_entries();
3100 }
3101
3102 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3103 public:
3104 bool doHeapRegion(HeapRegion* hr) {
3105 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3106 hr->verify_rem_set();
3107 }
3108 return false;
3109 }
3110 };
3111
3112 #ifdef ASSERT
3113 class VerifyCSetClosure: public HeapRegionClosure {
3114 public:
3115 bool doHeapRegion(HeapRegion* hr) {
3116 // Here we check that the CSet region's RSet is ready for parallel
3117 // iteration. The fields that we'll verify are only manipulated
3118 // when the region is part of a CSet and is collected. Afterwards,
3119 // we reset these fields when we clear the region's RSet (when the
3120 // region is freed) so they are ready when the region is
3121 // re-allocated. The only exception to this is if there's an
3122 // evacuation failure and instead of freeing the region we leave
3123 // it in the heap. In that case, we reset these fields during
3124 // evacuation failure handling.
3125 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3126
3127 // Here's a good place to add any other checks we'd like to
3128 // perform on CSet regions.
3129 return false;
3130 }
3131 };
3132 #endif // ASSERT
3133
3134 uint G1CollectedHeap::num_task_queues() const {
3135 return _task_queues->size();
3136 }
3137
3138 #if TASKQUEUE_STATS
3139 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3140 st->print_raw_cr("GC Task Stats");
3141 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3142 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3143 }
3144
3145 void G1CollectedHeap::print_taskqueue_stats() const {
3146 if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3147 return;
3148 }
3149 LogHandle(gc, task, stats) log;
3150 ResourceMark rm;
3151 outputStream* st = log.trace_stream();
3152
3153 print_taskqueue_stats_hdr(st);
3154
3155 TaskQueueStats totals;
3156 const uint n = num_task_queues();
3157 for (uint i = 0; i < n; ++i) {
3158 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3159 totals += task_queue(i)->stats;
3160 }
3161 st->print_raw("tot "); totals.print(st); st->cr();
3162
3163 DEBUG_ONLY(totals.verify());
3164 }
3165
3166 void G1CollectedHeap::reset_taskqueue_stats() {
3167 const uint n = num_task_queues();
3168 for (uint i = 0; i < n; ++i) {
3169 task_queue(i)->stats.reset();
3170 }
3171 }
3172 #endif // TASKQUEUE_STATS
3173
3174 void G1CollectedHeap::wait_for_root_region_scanning() {
3175 double scan_wait_start = os::elapsedTime();
3176 // We have to wait until the CM threads finish scanning the
3177 // root regions as it's the only way to ensure that all the
3178 // objects on them have been correctly scanned before we start
3179 // moving them during the GC.
3180 bool waited = _cm->root_regions()->wait_until_scan_finished();
3181 double wait_time_ms = 0.0;
3182 if (waited) {
3183 double scan_wait_end = os::elapsedTime();
3184 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3185 }
3186 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3187 }
3188
3189 bool
3190 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3191 assert_at_safepoint(true /* should_be_vm_thread */);
3192 guarantee(!is_gc_active(), "collection is not reentrant");
3193
3194 if (GCLocker::check_active_before_gc()) {
3195 return false;
3196 }
3197
3198 _gc_timer_stw->register_gc_start();
3199
3200 GCIdMark gc_id_mark;
3201 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3202
3203 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3204 ResourceMark rm;
3205
3206 wait_for_root_region_scanning();
3207
3208 print_heap_before_gc();
3209 trace_heap_before_gc(_gc_tracer_stw);
3210
3211 _verifier->verify_region_sets_optional();
3212 _verifier->verify_dirty_young_regions();
3213
3214 // This call will decide whether this pause is an initial-mark
3215 // pause. If it is, during_initial_mark_pause() will return true
3216 // for the duration of this pause.
3217 g1_policy()->decide_on_conc_mark_initiation();
3218
3219 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3220 assert(!collector_state()->during_initial_mark_pause() ||
3221 collector_state()->gcs_are_young(), "sanity");
3222
3223 // We also do not allow mixed GCs during marking.
3224 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3225
3226 // Record whether this pause is an initial mark. When the current
3227 // thread has completed its logging output and it's safe to signal
3228 // the CM thread, the flag's value in the policy has been reset.
3229 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3230
3231 // Inner scope for scope based logging, timers, and stats collection
3232 {
3233 EvacuationInfo evacuation_info;
3234
3235 if (collector_state()->during_initial_mark_pause()) {
3236 // We are about to start a marking cycle, so we increment the
3237 // full collection counter.
3238 increment_old_marking_cycles_started();
3239 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3240 }
3241
3242 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3243
3244 GCTraceCPUTime tcpu;
3245
3246 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3247 workers()->active_workers(),
3248 Threads::number_of_non_daemon_threads());
3249 workers()->set_active_workers(active_workers);
3250 FormatBuffer<> gc_string("Pause ");
3251 if (collector_state()->during_initial_mark_pause()) {
3252 gc_string.append("Initial Mark");
3253 } else if (collector_state()->gcs_are_young()) {
3254 gc_string.append("Young");
3255 } else {
3256 gc_string.append("Mixed");
3257 }
3258 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3259
3260 g1_policy()->note_gc_start(active_workers);
3261
3262 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3263 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3264
3265 // If the secondary_free_list is not empty, append it to the
3266 // free_list. No need to wait for the cleanup operation to finish;
3267 // the region allocation code will check the secondary_free_list
3268 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3269 // set, skip this step so that the region allocation code has to
3270 // get entries from the secondary_free_list.
3271 if (!G1StressConcRegionFreeing) {
3272 append_secondary_free_list_if_not_empty_with_lock();
3273 }
3274
3275 G1HeapTransition heap_transition(this);
3276 size_t heap_used_bytes_before_gc = used();
3277
3278 assert(check_young_list_well_formed(), "young list should be well formed");
3279
3280 // Don't dynamically change the number of GC threads this early. A value of
3281 // 0 is used to indicate serial work. When parallel work is done,
3282 // it will be set.
3283
3284 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3285 IsGCActiveMark x;
3286
3287 gc_prologue(false);
3288 increment_total_collections(false /* full gc */);
3289 increment_gc_time_stamp();
3290
3291 if (VerifyRememberedSets) {
3292 log_info(gc, verify)("[Verifying RemSets before GC]");
3293 VerifyRegionRemSetClosure v_cl;
3294 heap_region_iterate(&v_cl);
3295 }
3296
3297 _verifier->verify_before_gc();
3298
3299 _verifier->check_bitmaps("GC Start");
3300
3301 #if defined(COMPILER2) || INCLUDE_JVMCI
3302 DerivedPointerTable::clear();
3303 #endif
3304
3305 // Please see comment in g1CollectedHeap.hpp and
3306 // G1CollectedHeap::ref_processing_init() to see how
3307 // reference processing currently works in G1.
3308
3309 // Enable discovery in the STW reference processor
3310 if (g1_policy()->should_process_references()) {
3311 ref_processor_stw()->enable_discovery();
3312 } else {
3313 ref_processor_stw()->disable_discovery();
3314 }
3315
3316 {
3317 // We want to temporarily turn off discovery by the
3318 // CM ref processor, if necessary, and turn it back on
3319 // on again later if we do. Using a scoped
3320 // NoRefDiscovery object will do this.
3321 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3322
3323 // Forget the current alloc region (we might even choose it to be part
3324 // of the collection set!).
3325 _allocator->release_mutator_alloc_region();
3326
3327 // This timing is only used by the ergonomics to handle our pause target.
3328 // It is unclear why this should not include the full pause. We will
3329 // investigate this in CR 7178365.
3330 //
3331 // Preserving the old comment here if that helps the investigation:
3332 //
3333 // The elapsed time induced by the start time below deliberately elides
3334 // the possible verification above.
3335 double sample_start_time_sec = os::elapsedTime();
3336
3337 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3338
3339 if (collector_state()->during_initial_mark_pause()) {
3340 concurrent_mark()->checkpointRootsInitialPre();
3341 }
3342
3343 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3344 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3345
3346 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3347
3348 // Make sure the remembered sets are up to date. This needs to be
3349 // done before register_humongous_regions_with_cset(), because the
3350 // remembered sets are used there to choose eager reclaim candidates.
3351 // If the remembered sets are not up to date we might miss some
3352 // entries that need to be handled.
3353 g1_rem_set()->cleanupHRRS();
3354
3355 register_humongous_regions_with_cset();
3356
3357 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3358
3359 _cm->note_start_of_gc();
3360 // We call this after finalize_cset() to
3361 // ensure that the CSet has been finalized.
3362 _cm->verify_no_cset_oops();
3363
3364 if (_hr_printer.is_active()) {
3365 HeapRegion* hr = g1_policy()->collection_set();
3366 while (hr != NULL) {
3367 _hr_printer.cset(hr);
3368 hr = hr->next_in_collection_set();
3369 }
3370 }
3371
3372 #ifdef ASSERT
3373 VerifyCSetClosure cl;
3374 collection_set_iterate(&cl);
3375 #endif // ASSERT
3376
3377 // Initialize the GC alloc regions.
3378 _allocator->init_gc_alloc_regions(evacuation_info);
3379
3380 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3381 pre_evacuate_collection_set();
3382
3383 // Actually do the work...
3384 evacuate_collection_set(evacuation_info, &per_thread_states);
3385
3386 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3387
3388 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3389 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3390
3391 eagerly_reclaim_humongous_regions();
3392
3393 g1_policy()->clear_collection_set();
3394
3395 // Start a new incremental collection set for the next pause.
3396 g1_policy()->start_incremental_cset_building();
3397
3398 clear_cset_fast_test();
3399
3400 _young_list->reset_sampled_info();
3401
3402 // Don't check the whole heap at this point as the
3403 // GC alloc regions from this pause have been tagged
3404 // as survivors and moved on to the survivor list.
3405 // Survivor regions will fail the !is_young() check.
3406 assert(check_young_list_empty(false /* check_heap */),
3407 "young list should be empty");
3408
3409 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3410 _young_list->first_survivor_region(),
3411 _young_list->last_survivor_region());
3412
3413 _young_list->reset_auxilary_lists();
3414
3415 if (evacuation_failed()) {
3416 set_used(recalculate_used());
3417 if (_archive_allocator != NULL) {
3418 _archive_allocator->clear_used();
3419 }
3420 for (uint i = 0; i < ParallelGCThreads; i++) {
3421 if (_evacuation_failed_info_array[i].has_failed()) {
3422 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3423 }
3424 }
3425 } else {
3426 // The "used" of the the collection set have already been subtracted
3427 // when they were freed. Add in the bytes evacuated.
3428 increase_used(g1_policy()->bytes_copied_during_gc());
3429 }
3430
3431 if (collector_state()->during_initial_mark_pause()) {
3432 // We have to do this before we notify the CM threads that
3433 // they can start working to make sure that all the
3434 // appropriate initialization is done on the CM object.
3435 concurrent_mark()->checkpointRootsInitialPost();
3436 collector_state()->set_mark_in_progress(true);
3437 // Note that we don't actually trigger the CM thread at
3438 // this point. We do that later when we're sure that
3439 // the current thread has completed its logging output.
3440 }
3441
3442 allocate_dummy_regions();
3443
3444 _allocator->init_mutator_alloc_region();
3445
3446 {
3447 size_t expand_bytes = g1_policy()->expansion_amount();
3448 if (expand_bytes > 0) {
3449 size_t bytes_before = capacity();
3450 // No need for an ergo logging here,
3451 // expansion_amount() does this when it returns a value > 0.
3452 double expand_ms;
3453 if (!expand(expand_bytes, &expand_ms)) {
3454 // We failed to expand the heap. Cannot do anything about it.
3455 }
3456 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3457 }
3458 }
3459
3460 // We redo the verification but now wrt to the new CSet which
3461 // has just got initialized after the previous CSet was freed.
3462 _cm->verify_no_cset_oops();
3463 _cm->note_end_of_gc();
3464
3465 // This timing is only used by the ergonomics to handle our pause target.
3466 // It is unclear why this should not include the full pause. We will
3467 // investigate this in CR 7178365.
3468 double sample_end_time_sec = os::elapsedTime();
3469 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3470 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3471 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3472
3473 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3474 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3475
3476 MemoryService::track_memory_usage();
3477
3478 // In prepare_for_verify() below we'll need to scan the deferred
3479 // update buffers to bring the RSets up-to-date if
3480 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3481 // the update buffers we'll probably need to scan cards on the
3482 // regions we just allocated to (i.e., the GC alloc
3483 // regions). However, during the last GC we called
3484 // set_saved_mark() on all the GC alloc regions, so card
3485 // scanning might skip the [saved_mark_word()...top()] area of
3486 // those regions (i.e., the area we allocated objects into
3487 // during the last GC). But it shouldn't. Given that
3488 // saved_mark_word() is conditional on whether the GC time stamp
3489 // on the region is current or not, by incrementing the GC time
3490 // stamp here we invalidate all the GC time stamps on all the
3491 // regions and saved_mark_word() will simply return top() for
3492 // all the regions. This is a nicer way of ensuring this rather
3493 // than iterating over the regions and fixing them. In fact, the
3494 // GC time stamp increment here also ensures that
3495 // saved_mark_word() will return top() between pauses, i.e.,
3496 // during concurrent refinement. So we don't need the
3497 // is_gc_active() check to decided which top to use when
3498 // scanning cards (see CR 7039627).
3499 increment_gc_time_stamp();
3500
3501 if (VerifyRememberedSets) {
3502 log_info(gc, verify)("[Verifying RemSets after GC]");
3503 VerifyRegionRemSetClosure v_cl;
3504 heap_region_iterate(&v_cl);
3505 }
3506
3507 _verifier->verify_after_gc();
3508 _verifier->check_bitmaps("GC End");
3509
3510 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3511 ref_processor_stw()->verify_no_references_recorded();
3512
3513 // CM reference discovery will be re-enabled if necessary.
3514 }
3515
3516 #ifdef TRACESPINNING
3517 ParallelTaskTerminator::print_termination_counts();
3518 #endif
3519
3520 gc_epilogue(false);
3521 }
3522
3523 // Print the remainder of the GC log output.
3524 if (evacuation_failed()) {
3525 log_info(gc)("To-space exhausted");
3526 }
3527
3528 g1_policy()->print_phases();
3529 heap_transition.print();
3530
3531 // It is not yet to safe to tell the concurrent mark to
3532 // start as we have some optional output below. We don't want the
3533 // output from the concurrent mark thread interfering with this
3534 // logging output either.
3535
3536 _hrm.verify_optional();
3537 _verifier->verify_region_sets_optional();
3538
3539 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3540 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3541
3542 print_heap_after_gc();
3543 trace_heap_after_gc(_gc_tracer_stw);
3544
3545 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3546 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3547 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3548 // before any GC notifications are raised.
3549 g1mm()->update_sizes();
3550
3551 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3552 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3553 _gc_timer_stw->register_gc_end();
3554 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3555 }
3556 // It should now be safe to tell the concurrent mark thread to start
3557 // without its logging output interfering with the logging output
3558 // that came from the pause.
3559
3560 if (should_start_conc_mark) {
3561 // CAUTION: after the doConcurrentMark() call below,
3562 // the concurrent marking thread(s) could be running
3563 // concurrently with us. Make sure that anything after
3564 // this point does not assume that we are the only GC thread
3565 // running. Note: of course, the actual marking work will
3566 // not start until the safepoint itself is released in
3567 // SuspendibleThreadSet::desynchronize().
3568 doConcurrentMark();
3569 }
3570
3571 return true;
3572 }
3573
3574 void G1CollectedHeap::restore_preserved_marks() {
3575 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3576 workers()->run_task(&rpm_task);
3577 }
3578
3579 void G1CollectedHeap::remove_self_forwarding_pointers() {
3580 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3581 workers()->run_task(&rsfp_task);
3582 }
3583
3584 void G1CollectedHeap::restore_after_evac_failure() {
3585 double remove_self_forwards_start = os::elapsedTime();
3586
3587 remove_self_forwarding_pointers();
3588 restore_preserved_marks();
3589
3590 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3591 }
3592
3593 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3594 if (!_evacuation_failed) {
3595 _evacuation_failed = true;
3596 }
3597
3598 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3599
3600 // We want to call the "for_promotion_failure" version only in the
3601 // case of a promotion failure.
3602 if (m->must_be_preserved_for_promotion_failure(obj)) {
3603 OopAndMarkOop elem(obj, m);
3604 _preserved_objs[worker_id].push(elem);
3605 }
3606 }
3607
3608 bool G1ParEvacuateFollowersClosure::offer_termination() {
3609 G1ParScanThreadState* const pss = par_scan_state();
3610 start_term_time();
3611 const bool res = terminator()->offer_termination();
3612 end_term_time();
3613 return res;
3614 }
3615
3616 void G1ParEvacuateFollowersClosure::do_void() {
3617 G1ParScanThreadState* const pss = par_scan_state();
3618 pss->trim_queue();
3619 do {
3620 pss->steal_and_trim_queue(queues());
3621 } while (!offer_termination());
3622 }
3623
3624 class G1ParTask : public AbstractGangTask {
3625 protected:
3626 G1CollectedHeap* _g1h;
3627 G1ParScanThreadStateSet* _pss;
3628 RefToScanQueueSet* _queues;
3629 G1RootProcessor* _root_processor;
3630 ParallelTaskTerminator _terminator;
3631 uint _n_workers;
3632
3633 public:
3634 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3635 : AbstractGangTask("G1 collection"),
3636 _g1h(g1h),
3637 _pss(per_thread_states),
3638 _queues(task_queues),
3639 _root_processor(root_processor),
3640 _terminator(n_workers, _queues),
3641 _n_workers(n_workers)
3642 {}
3643
3644 void work(uint worker_id) {
3645 if (worker_id >= _n_workers) return; // no work needed this round
3646
3647 double start_sec = os::elapsedTime();
3648 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3649
3650 {
3651 ResourceMark rm;
3652 HandleMark hm;
3653
3654 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3655
3656 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3657 pss->set_ref_processor(rp);
3658
3659 double start_strong_roots_sec = os::elapsedTime();
3660
3661 _root_processor->evacuate_roots(pss->closures(), worker_id);
3662
3663 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3664
3665 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3666 // treating the nmethods visited to act as roots for concurrent marking.
3667 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3668 // objects copied by the current evacuation.
3669 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3670 pss->closures()->weak_codeblobs(),
3671 worker_id);
3672
3673 _pss->add_cards_scanned(worker_id, cards_scanned);
3674
3675 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3676
3677 double term_sec = 0.0;
3678 size_t evac_term_attempts = 0;
3679 {
3680 double start = os::elapsedTime();
3681 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3682 evac.do_void();
3683
3684 evac_term_attempts = evac.term_attempts();
3685 term_sec = evac.term_time();
3686 double elapsed_sec = os::elapsedTime() - start;
3687 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3688 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3689 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3690 }
3691
3692 assert(pss->queue_is_empty(), "should be empty");
3693
3694 if (log_is_enabled(Debug, gc, task, stats)) {
3695 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3696 size_t lab_waste;
3697 size_t lab_undo_waste;
3698 pss->waste(lab_waste, lab_undo_waste);
3699 _g1h->print_termination_stats(worker_id,
3700 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3701 strong_roots_sec * 1000.0, /* strong roots time */
3702 term_sec * 1000.0, /* evac term time */
3703 evac_term_attempts, /* evac term attempts */
3704 lab_waste, /* alloc buffer waste */
3705 lab_undo_waste /* undo waste */
3706 );
3707 }
3708
3709 // Close the inner scope so that the ResourceMark and HandleMark
3710 // destructors are executed here and are included as part of the
3711 // "GC Worker Time".
3712 }
3713 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3714 }
3715 };
3716
3717 void G1CollectedHeap::print_termination_stats_hdr() {
3718 log_debug(gc, task, stats)("GC Termination Stats");
3719 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3720 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3721 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3722 }
3723
3724 void G1CollectedHeap::print_termination_stats(uint worker_id,
3725 double elapsed_ms,
3726 double strong_roots_ms,
3727 double term_ms,
3728 size_t term_attempts,
3729 size_t alloc_buffer_waste,
3730 size_t undo_waste) const {
3731 log_debug(gc, task, stats)
3732 ("%3d %9.2f %9.2f %6.2f "
3733 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3734 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3735 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3736 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3737 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3738 alloc_buffer_waste * HeapWordSize / K,
3739 undo_waste * HeapWordSize / K);
3740 }
3741
3742 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3743 private:
3744 BoolObjectClosure* _is_alive;
3745 int _initial_string_table_size;
3746 int _initial_symbol_table_size;
3747
3748 bool _process_strings;
3749 int _strings_processed;
3750 int _strings_removed;
3751
3752 bool _process_symbols;
3753 int _symbols_processed;
3754 int _symbols_removed;
3755
3756 public:
3757 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3758 AbstractGangTask("String/Symbol Unlinking"),
3759 _is_alive(is_alive),
3760 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3761 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3762
3763 _initial_string_table_size = StringTable::the_table()->table_size();
3764 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3765 if (process_strings) {
3766 StringTable::clear_parallel_claimed_index();
3767 }
3768 if (process_symbols) {
3769 SymbolTable::clear_parallel_claimed_index();
3770 }
3771 }
3772
3773 ~G1StringSymbolTableUnlinkTask() {
3774 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3775 "claim value %d after unlink less than initial string table size %d",
3776 StringTable::parallel_claimed_index(), _initial_string_table_size);
3777 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3778 "claim value %d after unlink less than initial symbol table size %d",
3779 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3780
3781 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3782 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3783 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3784 strings_processed(), strings_removed(),
3785 symbols_processed(), symbols_removed());
3786 }
3787
3788 void work(uint worker_id) {
3789 int strings_processed = 0;
3790 int strings_removed = 0;
3791 int symbols_processed = 0;
3792 int symbols_removed = 0;
3793 if (_process_strings) {
3794 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3795 Atomic::add(strings_processed, &_strings_processed);
3796 Atomic::add(strings_removed, &_strings_removed);
3797 }
3798 if (_process_symbols) {
3799 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3800 Atomic::add(symbols_processed, &_symbols_processed);
3801 Atomic::add(symbols_removed, &_symbols_removed);
3802 }
3803 }
3804
3805 size_t strings_processed() const { return (size_t)_strings_processed; }
3806 size_t strings_removed() const { return (size_t)_strings_removed; }
3807
3808 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3809 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3810 };
3811
3812 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3813 private:
3814 static Monitor* _lock;
3815
3816 BoolObjectClosure* const _is_alive;
3817 const bool _unloading_occurred;
3818 const uint _num_workers;
3819
3820 // Variables used to claim nmethods.
3821 nmethod* _first_nmethod;
3822 volatile nmethod* _claimed_nmethod;
3823
3824 // The list of nmethods that need to be processed by the second pass.
3825 volatile nmethod* _postponed_list;
3826 volatile uint _num_entered_barrier;
3827
3828 public:
3829 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3830 _is_alive(is_alive),
3831 _unloading_occurred(unloading_occurred),
3832 _num_workers(num_workers),
3833 _first_nmethod(NULL),
3834 _claimed_nmethod(NULL),
3835 _postponed_list(NULL),
3836 _num_entered_barrier(0)
3837 {
3838 nmethod::increase_unloading_clock();
3839 // Get first alive nmethod
3840 NMethodIterator iter = NMethodIterator();
3841 if(iter.next_alive()) {
3842 _first_nmethod = iter.method();
3843 }
3844 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3845 }
3846
3847 ~G1CodeCacheUnloadingTask() {
3848 CodeCache::verify_clean_inline_caches();
3849
3850 CodeCache::set_needs_cache_clean(false);
3851 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3852
3853 CodeCache::verify_icholder_relocations();
3854 }
3855
3856 private:
3857 void add_to_postponed_list(nmethod* nm) {
3858 nmethod* old;
3859 do {
3860 old = (nmethod*)_postponed_list;
3861 nm->set_unloading_next(old);
3862 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3863 }
3864
3865 void clean_nmethod(nmethod* nm) {
3866 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3867
3868 if (postponed) {
3869 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3870 add_to_postponed_list(nm);
3871 }
3872
3873 // Mark that this thread has been cleaned/unloaded.
3874 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3875 nm->set_unloading_clock(nmethod::global_unloading_clock());
3876 }
3877
3878 void clean_nmethod_postponed(nmethod* nm) {
3879 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3880 }
3881
3882 static const int MaxClaimNmethods = 16;
3883
3884 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3885 nmethod* first;
3886 NMethodIterator last;
3887
3888 do {
3889 *num_claimed_nmethods = 0;
3890
3891 first = (nmethod*)_claimed_nmethod;
3892 last = NMethodIterator(first);
3893
3894 if (first != NULL) {
3895
3896 for (int i = 0; i < MaxClaimNmethods; i++) {
3897 if (!last.next_alive()) {
3898 break;
3899 }
3900 claimed_nmethods[i] = last.method();
3901 (*num_claimed_nmethods)++;
3902 }
3903 }
3904
3905 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3906 }
3907
3908 nmethod* claim_postponed_nmethod() {
3909 nmethod* claim;
3910 nmethod* next;
3911
3912 do {
3913 claim = (nmethod*)_postponed_list;
3914 if (claim == NULL) {
3915 return NULL;
3916 }
3917
3918 next = claim->unloading_next();
3919
3920 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3921
3922 return claim;
3923 }
3924
3925 public:
3926 // Mark that we're done with the first pass of nmethod cleaning.
3927 void barrier_mark(uint worker_id) {
3928 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3929 _num_entered_barrier++;
3930 if (_num_entered_barrier == _num_workers) {
3931 ml.notify_all();
3932 }
3933 }
3934
3935 // See if we have to wait for the other workers to
3936 // finish their first-pass nmethod cleaning work.
3937 void barrier_wait(uint worker_id) {
3938 if (_num_entered_barrier < _num_workers) {
3939 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3940 while (_num_entered_barrier < _num_workers) {
3941 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3942 }
3943 }
3944 }
3945
3946 // Cleaning and unloading of nmethods. Some work has to be postponed
3947 // to the second pass, when we know which nmethods survive.
3948 void work_first_pass(uint worker_id) {
3949 // The first nmethods is claimed by the first worker.
3950 if (worker_id == 0 && _first_nmethod != NULL) {
3951 clean_nmethod(_first_nmethod);
3952 _first_nmethod = NULL;
3953 }
3954
3955 int num_claimed_nmethods;
3956 nmethod* claimed_nmethods[MaxClaimNmethods];
3957
3958 while (true) {
3959 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3960
3961 if (num_claimed_nmethods == 0) {
3962 break;
3963 }
3964
3965 for (int i = 0; i < num_claimed_nmethods; i++) {
3966 clean_nmethod(claimed_nmethods[i]);
3967 }
3968 }
3969 }
3970
3971 void work_second_pass(uint worker_id) {
3972 nmethod* nm;
3973 // Take care of postponed nmethods.
3974 while ((nm = claim_postponed_nmethod()) != NULL) {
3975 clean_nmethod_postponed(nm);
3976 }
3977 }
3978 };
3979
3980 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3981
3982 class G1KlassCleaningTask : public StackObj {
3983 BoolObjectClosure* _is_alive;
3984 volatile jint _clean_klass_tree_claimed;
3985 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3986
3987 public:
3988 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3989 _is_alive(is_alive),
3990 _clean_klass_tree_claimed(0),
3991 _klass_iterator() {
3992 }
3993
3994 private:
3995 bool claim_clean_klass_tree_task() {
3996 if (_clean_klass_tree_claimed) {
3997 return false;
3998 }
3999
4000 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4001 }
4002
4003 InstanceKlass* claim_next_klass() {
4004 Klass* klass;
4005 do {
4006 klass =_klass_iterator.next_klass();
4007 } while (klass != NULL && !klass->is_instance_klass());
4008
4009 // this can be null so don't call InstanceKlass::cast
4010 return static_cast<InstanceKlass*>(klass);
4011 }
4012
4013 public:
4014
4015 void clean_klass(InstanceKlass* ik) {
4016 ik->clean_weak_instanceklass_links(_is_alive);
4017 }
4018
4019 void work() {
4020 ResourceMark rm;
4021
4022 // One worker will clean the subklass/sibling klass tree.
4023 if (claim_clean_klass_tree_task()) {
4024 Klass::clean_subklass_tree(_is_alive);
4025 }
4026
4027 // All workers will help cleaning the classes,
4028 InstanceKlass* klass;
4029 while ((klass = claim_next_klass()) != NULL) {
4030 clean_klass(klass);
4031 }
4032 }
4033 };
4034
4035 // To minimize the remark pause times, the tasks below are done in parallel.
4036 class G1ParallelCleaningTask : public AbstractGangTask {
4037 private:
4038 G1StringSymbolTableUnlinkTask _string_symbol_task;
4039 G1CodeCacheUnloadingTask _code_cache_task;
4040 G1KlassCleaningTask _klass_cleaning_task;
4041
4042 public:
4043 // The constructor is run in the VMThread.
4044 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4045 AbstractGangTask("Parallel Cleaning"),
4046 _string_symbol_task(is_alive, process_strings, process_symbols),
4047 _code_cache_task(num_workers, is_alive, unloading_occurred),
4048 _klass_cleaning_task(is_alive) {
4049 }
4050
4051 // The parallel work done by all worker threads.
4052 void work(uint worker_id) {
4053 // Do first pass of code cache cleaning.
4054 _code_cache_task.work_first_pass(worker_id);
4055
4056 // Let the threads mark that the first pass is done.
4057 _code_cache_task.barrier_mark(worker_id);
4058
4059 // Clean the Strings and Symbols.
4060 _string_symbol_task.work(worker_id);
4061
4062 // Wait for all workers to finish the first code cache cleaning pass.
4063 _code_cache_task.barrier_wait(worker_id);
4064
4065 // Do the second code cache cleaning work, which realize on
4066 // the liveness information gathered during the first pass.
4067 _code_cache_task.work_second_pass(worker_id);
4068
4069 // Clean all klasses that were not unloaded.
4070 _klass_cleaning_task.work();
4071 }
4072 };
4073
4074
4075 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4076 bool process_strings,
4077 bool process_symbols,
4078 bool class_unloading_occurred) {
4079 uint n_workers = workers()->active_workers();
4080
4081 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4082 n_workers, class_unloading_occurred);
4083 workers()->run_task(&g1_unlink_task);
4084 }
4085
4086 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4087 bool process_strings, bool process_symbols) {
4088 {
4089 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4090 workers()->run_task(&g1_unlink_task);
4091 }
4092
4093 if (G1StringDedup::is_enabled()) {
4094 G1StringDedup::unlink(is_alive);
4095 }
4096 }
4097
4098 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4099 private:
4100 DirtyCardQueueSet* _queue;
4101 G1CollectedHeap* _g1h;
4102 public:
4103 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4104 _queue(queue), _g1h(g1h) { }
4105
4106 virtual void work(uint worker_id) {
4107 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4108 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4109
4110 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4111 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4112
4113 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4114 }
4115 };
4116
4117 void G1CollectedHeap::redirty_logged_cards() {
4118 double redirty_logged_cards_start = os::elapsedTime();
4119
4120 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4121 dirty_card_queue_set().reset_for_par_iteration();
4122 workers()->run_task(&redirty_task);
4123
4124 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4125 dcq.merge_bufferlists(&dirty_card_queue_set());
4126 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4127
4128 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4129 }
4130
4131 // Weak Reference Processing support
4132
4133 // An always "is_alive" closure that is used to preserve referents.
4134 // If the object is non-null then it's alive. Used in the preservation
4135 // of referent objects that are pointed to by reference objects
4136 // discovered by the CM ref processor.
4137 class G1AlwaysAliveClosure: public BoolObjectClosure {
4138 G1CollectedHeap* _g1;
4139 public:
4140 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4141 bool do_object_b(oop p) {
4142 if (p != NULL) {
4143 return true;
4144 }
4145 return false;
4146 }
4147 };
4148
4149 bool G1STWIsAliveClosure::do_object_b(oop p) {
4150 // An object is reachable if it is outside the collection set,
4151 // or is inside and copied.
4152 return !_g1->is_in_cset(p) || p->is_forwarded();
4153 }
4154
4155 // Non Copying Keep Alive closure
4156 class G1KeepAliveClosure: public OopClosure {
4157 G1CollectedHeap* _g1;
4158 public:
4159 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4160 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4161 void do_oop(oop* p) {
4162 oop obj = *p;
4163 assert(obj != NULL, "the caller should have filtered out NULL values");
4164
4165 const InCSetState cset_state = _g1->in_cset_state(obj);
4166 if (!cset_state.is_in_cset_or_humongous()) {
4167 return;
4168 }
4169 if (cset_state.is_in_cset()) {
4170 assert( obj->is_forwarded(), "invariant" );
4171 *p = obj->forwardee();
4172 } else {
4173 assert(!obj->is_forwarded(), "invariant" );
4174 assert(cset_state.is_humongous(),
4175 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4176 _g1->set_humongous_is_live(obj);
4177 }
4178 }
4179 };
4180
4181 // Copying Keep Alive closure - can be called from both
4182 // serial and parallel code as long as different worker
4183 // threads utilize different G1ParScanThreadState instances
4184 // and different queues.
4185
4186 class G1CopyingKeepAliveClosure: public OopClosure {
4187 G1CollectedHeap* _g1h;
4188 OopClosure* _copy_non_heap_obj_cl;
4189 G1ParScanThreadState* _par_scan_state;
4190
4191 public:
4192 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4193 OopClosure* non_heap_obj_cl,
4194 G1ParScanThreadState* pss):
4195 _g1h(g1h),
4196 _copy_non_heap_obj_cl(non_heap_obj_cl),
4197 _par_scan_state(pss)
4198 {}
4199
4200 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4201 virtual void do_oop( oop* p) { do_oop_work(p); }
4202
4203 template <class T> void do_oop_work(T* p) {
4204 oop obj = oopDesc::load_decode_heap_oop(p);
4205
4206 if (_g1h->is_in_cset_or_humongous(obj)) {
4207 // If the referent object has been forwarded (either copied
4208 // to a new location or to itself in the event of an
4209 // evacuation failure) then we need to update the reference
4210 // field and, if both reference and referent are in the G1
4211 // heap, update the RSet for the referent.
4212 //
4213 // If the referent has not been forwarded then we have to keep
4214 // it alive by policy. Therefore we have copy the referent.
4215 //
4216 // If the reference field is in the G1 heap then we can push
4217 // on the PSS queue. When the queue is drained (after each
4218 // phase of reference processing) the object and it's followers
4219 // will be copied, the reference field set to point to the
4220 // new location, and the RSet updated. Otherwise we need to
4221 // use the the non-heap or metadata closures directly to copy
4222 // the referent object and update the pointer, while avoiding
4223 // updating the RSet.
4224
4225 if (_g1h->is_in_g1_reserved(p)) {
4226 _par_scan_state->push_on_queue(p);
4227 } else {
4228 assert(!Metaspace::contains((const void*)p),
4229 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4230 _copy_non_heap_obj_cl->do_oop(p);
4231 }
4232 }
4233 }
4234 };
4235
4236 // Serial drain queue closure. Called as the 'complete_gc'
4237 // closure for each discovered list in some of the
4238 // reference processing phases.
4239
4240 class G1STWDrainQueueClosure: public VoidClosure {
4241 protected:
4242 G1CollectedHeap* _g1h;
4243 G1ParScanThreadState* _par_scan_state;
4244
4245 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4246
4247 public:
4248 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4249 _g1h(g1h),
4250 _par_scan_state(pss)
4251 { }
4252
4253 void do_void() {
4254 G1ParScanThreadState* const pss = par_scan_state();
4255 pss->trim_queue();
4256 }
4257 };
4258
4259 // Parallel Reference Processing closures
4260
4261 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4262 // processing during G1 evacuation pauses.
4263
4264 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4265 private:
4266 G1CollectedHeap* _g1h;
4267 G1ParScanThreadStateSet* _pss;
4268 RefToScanQueueSet* _queues;
4269 WorkGang* _workers;
4270 uint _active_workers;
4271
4272 public:
4273 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4274 G1ParScanThreadStateSet* per_thread_states,
4275 WorkGang* workers,
4276 RefToScanQueueSet *task_queues,
4277 uint n_workers) :
4278 _g1h(g1h),
4279 _pss(per_thread_states),
4280 _queues(task_queues),
4281 _workers(workers),
4282 _active_workers(n_workers)
4283 {
4284 assert(n_workers > 0, "shouldn't call this otherwise");
4285 }
4286
4287 // Executes the given task using concurrent marking worker threads.
4288 virtual void execute(ProcessTask& task);
4289 virtual void execute(EnqueueTask& task);
4290 };
4291
4292 // Gang task for possibly parallel reference processing
4293
4294 class G1STWRefProcTaskProxy: public AbstractGangTask {
4295 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4296 ProcessTask& _proc_task;
4297 G1CollectedHeap* _g1h;
4298 G1ParScanThreadStateSet* _pss;
4299 RefToScanQueueSet* _task_queues;
4300 ParallelTaskTerminator* _terminator;
4301
4302 public:
4303 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4304 G1CollectedHeap* g1h,
4305 G1ParScanThreadStateSet* per_thread_states,
4306 RefToScanQueueSet *task_queues,
4307 ParallelTaskTerminator* terminator) :
4308 AbstractGangTask("Process reference objects in parallel"),
4309 _proc_task(proc_task),
4310 _g1h(g1h),
4311 _pss(per_thread_states),
4312 _task_queues(task_queues),
4313 _terminator(terminator)
4314 {}
4315
4316 virtual void work(uint worker_id) {
4317 // The reference processing task executed by a single worker.
4318 ResourceMark rm;
4319 HandleMark hm;
4320
4321 G1STWIsAliveClosure is_alive(_g1h);
4322
4323 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4324 pss->set_ref_processor(NULL);
4325
4326 // Keep alive closure.
4327 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4328
4329 // Complete GC closure
4330 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4331
4332 // Call the reference processing task's work routine.
4333 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4334
4335 // Note we cannot assert that the refs array is empty here as not all
4336 // of the processing tasks (specifically phase2 - pp2_work) execute
4337 // the complete_gc closure (which ordinarily would drain the queue) so
4338 // the queue may not be empty.
4339 }
4340 };
4341
4342 // Driver routine for parallel reference processing.
4343 // Creates an instance of the ref processing gang
4344 // task and has the worker threads execute it.
4345 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4346 assert(_workers != NULL, "Need parallel worker threads.");
4347
4348 ParallelTaskTerminator terminator(_active_workers, _queues);
4349 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4350
4351 _workers->run_task(&proc_task_proxy);
4352 }
4353
4354 // Gang task for parallel reference enqueueing.
4355
4356 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4357 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4358 EnqueueTask& _enq_task;
4359
4360 public:
4361 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4362 AbstractGangTask("Enqueue reference objects in parallel"),
4363 _enq_task(enq_task)
4364 { }
4365
4366 virtual void work(uint worker_id) {
4367 _enq_task.work(worker_id);
4368 }
4369 };
4370
4371 // Driver routine for parallel reference enqueueing.
4372 // Creates an instance of the ref enqueueing gang
4373 // task and has the worker threads execute it.
4374
4375 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4376 assert(_workers != NULL, "Need parallel worker threads.");
4377
4378 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4379
4380 _workers->run_task(&enq_task_proxy);
4381 }
4382
4383 // End of weak reference support closures
4384
4385 // Abstract task used to preserve (i.e. copy) any referent objects
4386 // that are in the collection set and are pointed to by reference
4387 // objects discovered by the CM ref processor.
4388
4389 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4390 protected:
4391 G1CollectedHeap* _g1h;
4392 G1ParScanThreadStateSet* _pss;
4393 RefToScanQueueSet* _queues;
4394 ParallelTaskTerminator _terminator;
4395 uint _n_workers;
4396
4397 public:
4398 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4399 AbstractGangTask("ParPreserveCMReferents"),
4400 _g1h(g1h),
4401 _pss(per_thread_states),
4402 _queues(task_queues),
4403 _terminator(workers, _queues),
4404 _n_workers(workers)
4405 { }
4406
4407 void work(uint worker_id) {
4408 ResourceMark rm;
4409 HandleMark hm;
4410
4411 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4412 pss->set_ref_processor(NULL);
4413 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4414
4415 // Is alive closure
4416 G1AlwaysAliveClosure always_alive(_g1h);
4417
4418 // Copying keep alive closure. Applied to referent objects that need
4419 // to be copied.
4420 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4421
4422 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4423
4424 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4425 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4426
4427 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4428 // So this must be true - but assert just in case someone decides to
4429 // change the worker ids.
4430 assert(worker_id < limit, "sanity");
4431 assert(!rp->discovery_is_atomic(), "check this code");
4432
4433 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4434 for (uint idx = worker_id; idx < limit; idx += stride) {
4435 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4436
4437 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4438 while (iter.has_next()) {
4439 // Since discovery is not atomic for the CM ref processor, we
4440 // can see some null referent objects.
4441 iter.load_ptrs(DEBUG_ONLY(true));
4442 oop ref = iter.obj();
4443
4444 // This will filter nulls.
4445 if (iter.is_referent_alive()) {
4446 iter.make_referent_alive();
4447 }
4448 iter.move_to_next();
4449 }
4450 }
4451
4452 // Drain the queue - which may cause stealing
4453 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4454 drain_queue.do_void();
4455 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4456 assert(pss->queue_is_empty(), "should be");
4457 }
4458 };
4459
4460 void G1CollectedHeap::process_weak_jni_handles() {
4461 double ref_proc_start = os::elapsedTime();
4462
4463 G1STWIsAliveClosure is_alive(this);
4464 G1KeepAliveClosure keep_alive(this);
4465 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4466
4467 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4468 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4469 }
4470
4471 // Weak Reference processing during an evacuation pause (part 1).
4472 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4473 double ref_proc_start = os::elapsedTime();
4474
4475 ReferenceProcessor* rp = _ref_processor_stw;
4476 assert(rp->discovery_enabled(), "should have been enabled");
4477
4478 // Any reference objects, in the collection set, that were 'discovered'
4479 // by the CM ref processor should have already been copied (either by
4480 // applying the external root copy closure to the discovered lists, or
4481 // by following an RSet entry).
4482 //
4483 // But some of the referents, that are in the collection set, that these
4484 // reference objects point to may not have been copied: the STW ref
4485 // processor would have seen that the reference object had already
4486 // been 'discovered' and would have skipped discovering the reference,
4487 // but would not have treated the reference object as a regular oop.
4488 // As a result the copy closure would not have been applied to the
4489 // referent object.
4490 //
4491 // We need to explicitly copy these referent objects - the references
4492 // will be processed at the end of remarking.
4493 //
4494 // We also need to do this copying before we process the reference
4495 // objects discovered by the STW ref processor in case one of these
4496 // referents points to another object which is also referenced by an
4497 // object discovered by the STW ref processor.
4498
4499 uint no_of_gc_workers = workers()->active_workers();
4500
4501 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4502 per_thread_states,
4503 no_of_gc_workers,
4504 _task_queues);
4505
4506 workers()->run_task(&keep_cm_referents);
4507
4508 // Closure to test whether a referent is alive.
4509 G1STWIsAliveClosure is_alive(this);
4510
4511 // Even when parallel reference processing is enabled, the processing
4512 // of JNI refs is serial and performed serially by the current thread
4513 // rather than by a worker. The following PSS will be used for processing
4514 // JNI refs.
4515
4516 // Use only a single queue for this PSS.
4517 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4518 pss->set_ref_processor(NULL);
4519 assert(pss->queue_is_empty(), "pre-condition");
4520
4521 // Keep alive closure.
4522 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4523
4524 // Serial Complete GC closure
4525 G1STWDrainQueueClosure drain_queue(this, pss);
4526
4527 // Setup the soft refs policy...
4528 rp->setup_policy(false);
4529
4530 ReferenceProcessorStats stats;
4531 if (!rp->processing_is_mt()) {
4532 // Serial reference processing...
4533 stats = rp->process_discovered_references(&is_alive,
4534 &keep_alive,
4535 &drain_queue,
4536 NULL,
4537 _gc_timer_stw);
4538 } else {
4539 // Parallel reference processing
4540 assert(rp->num_q() == no_of_gc_workers, "sanity");
4541 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4542
4543 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4544 stats = rp->process_discovered_references(&is_alive,
4545 &keep_alive,
4546 &drain_queue,
4547 &par_task_executor,
4548 _gc_timer_stw);
4549 }
4550
4551 _gc_tracer_stw->report_gc_reference_stats(stats);
4552
4553 // We have completed copying any necessary live referent objects.
4554 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4555
4556 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4557 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4558 }
4559
4560 // Weak Reference processing during an evacuation pause (part 2).
4561 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4562 double ref_enq_start = os::elapsedTime();
4563
4564 ReferenceProcessor* rp = _ref_processor_stw;
4565 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4566
4567 // Now enqueue any remaining on the discovered lists on to
4568 // the pending list.
4569 if (!rp->processing_is_mt()) {
4570 // Serial reference processing...
4571 rp->enqueue_discovered_references();
4572 } else {
4573 // Parallel reference enqueueing
4574
4575 uint n_workers = workers()->active_workers();
4576
4577 assert(rp->num_q() == n_workers, "sanity");
4578 assert(n_workers <= rp->max_num_q(), "sanity");
4579
4580 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4581 rp->enqueue_discovered_references(&par_task_executor);
4582 }
4583
4584 rp->verify_no_references_recorded();
4585 assert(!rp->discovery_enabled(), "should have been disabled");
4586
4587 // FIXME
4588 // CM's reference processing also cleans up the string and symbol tables.
4589 // Should we do that here also? We could, but it is a serial operation
4590 // and could significantly increase the pause time.
4591
4592 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4593 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4594 }
4595
4596 void G1CollectedHeap::pre_evacuate_collection_set() {
4597 _expand_heap_after_alloc_failure = true;
4598 _evacuation_failed = false;
4599
4600 // Disable the hot card cache.
4601 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4602 hot_card_cache->reset_hot_cache_claimed_index();
4603 hot_card_cache->set_use_cache(false);
4604
4605 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4606 }
4607
4608 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4609 // Should G1EvacuationFailureALot be in effect for this GC?
4610 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4611
4612 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4613 double start_par_time_sec = os::elapsedTime();
4614 double end_par_time_sec;
4615
4616 {
4617 const uint n_workers = workers()->active_workers();
4618 G1RootProcessor root_processor(this, n_workers);
4619 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4620 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4621 if (collector_state()->during_initial_mark_pause()) {
4622 ClassLoaderDataGraph::clear_claimed_marks();
4623 }
4624
4625 print_termination_stats_hdr();
4626
4627 workers()->run_task(&g1_par_task);
4628 end_par_time_sec = os::elapsedTime();
4629
4630 // Closing the inner scope will execute the destructor
4631 // for the G1RootProcessor object. We record the current
4632 // elapsed time before closing the scope so that time
4633 // taken for the destructor is NOT included in the
4634 // reported parallel time.
4635 }
4636
4637 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4638
4639 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4640 phase_times->record_par_time(par_time_ms);
4641
4642 double code_root_fixup_time_ms =
4643 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4644 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4645 }
4646
4647 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4648 // Process any discovered reference objects - we have
4649 // to do this _before_ we retire the GC alloc regions
4650 // as we may have to copy some 'reachable' referent
4651 // objects (and their reachable sub-graphs) that were
4652 // not copied during the pause.
4653 if (g1_policy()->should_process_references()) {
4654 process_discovered_references(per_thread_states);
4655 } else {
4656 ref_processor_stw()->verify_no_references_recorded();
4657 process_weak_jni_handles();
4658 }
4659
4660 if (G1StringDedup::is_enabled()) {
4661 double fixup_start = os::elapsedTime();
4662
4663 G1STWIsAliveClosure is_alive(this);
4664 G1KeepAliveClosure keep_alive(this);
4665 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4666
4667 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4668 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4669 }
4670
4671 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4672
4673 if (evacuation_failed()) {
4674 restore_after_evac_failure();
4675
4676 // Reset the G1EvacuationFailureALot counters and flags
4677 // Note: the values are reset only when an actual
4678 // evacuation failure occurs.
4679 NOT_PRODUCT(reset_evacuation_should_fail();)
4680 }
4681
4682 // Enqueue any remaining references remaining on the STW
4683 // reference processor's discovered lists. We need to do
4684 // this after the card table is cleaned (and verified) as
4685 // the act of enqueueing entries on to the pending list
4686 // will log these updates (and dirty their associated
4687 // cards). We need these updates logged to update any
4688 // RSets.
4689 if (g1_policy()->should_process_references()) {
4690 enqueue_discovered_references(per_thread_states);
4691 } else {
4692 g1_policy()->phase_times()->record_ref_enq_time(0);
4693 }
4694
4695 _allocator->release_gc_alloc_regions(evacuation_info);
4696
4697 per_thread_states->flush();
4698
4699 record_obj_copy_mem_stats();
4700
4701 _survivor_evac_stats.adjust_desired_plab_sz();
4702 _old_evac_stats.adjust_desired_plab_sz();
4703
4704 // Reset and re-enable the hot card cache.
4705 // Note the counts for the cards in the regions in the
4706 // collection set are reset when the collection set is freed.
4707 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4708 hot_card_cache->reset_hot_cache();
4709 hot_card_cache->set_use_cache(true);
4710
4711 purge_code_root_memory();
4712
4713 redirty_logged_cards();
4714 #if defined(COMPILER2) || INCLUDE_JVMCI
4715 DerivedPointerTable::update_pointers();
4716 #endif
4717 }
4718
4719 void G1CollectedHeap::record_obj_copy_mem_stats() {
4720 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4721
4722 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4723 create_g1_evac_summary(&_old_evac_stats));
4724 }
4725
4726 void G1CollectedHeap::free_region(HeapRegion* hr,
4727 FreeRegionList* free_list,
4728 bool par,
4729 bool locked) {
4730 assert(!hr->is_free(), "the region should not be free");
4731 assert(!hr->is_empty(), "the region should not be empty");
4732 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4733 assert(free_list != NULL, "pre-condition");
4734
4735 if (G1VerifyBitmaps) {
4736 MemRegion mr(hr->bottom(), hr->end());
4737 concurrent_mark()->clearRangePrevBitmap(mr);
4738 }
4739
4740 // Clear the card counts for this region.
4741 // Note: we only need to do this if the region is not young
4742 // (since we don't refine cards in young regions).
4743 if (!hr->is_young()) {
4744 _cg1r->hot_card_cache()->reset_card_counts(hr);
4745 }
4746 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4747 free_list->add_ordered(hr);
4748 }
4749
4750 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4751 FreeRegionList* free_list,
4752 bool par) {
4753 assert(hr->is_humongous(), "this is only for humongous regions");
4754 assert(free_list != NULL, "pre-condition");
4755 hr->clear_humongous();
4756 free_region(hr, free_list, par);
4757 }
4758
4759 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4760 const uint humongous_regions_removed) {
4761 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4762 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4763 _old_set.bulk_remove(old_regions_removed);
4764 _humongous_set.bulk_remove(humongous_regions_removed);
4765 }
4766
4767 }
4768
4769 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4770 assert(list != NULL, "list can't be null");
4771 if (!list->is_empty()) {
4772 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4773 _hrm.insert_list_into_free_list(list);
4774 }
4775 }
4776
4777 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4778 decrease_used(bytes);
4779 }
4780
4781 class G1ParCleanupCTTask : public AbstractGangTask {
4782 G1SATBCardTableModRefBS* _ct_bs;
4783 G1CollectedHeap* _g1h;
4784 HeapRegion* volatile _su_head;
4785 public:
4786 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4787 G1CollectedHeap* g1h) :
4788 AbstractGangTask("G1 Par Cleanup CT Task"),
4789 _ct_bs(ct_bs), _g1h(g1h) { }
4790
4791 void work(uint worker_id) {
4792 HeapRegion* r;
4793 while (r = _g1h->pop_dirty_cards_region()) {
4794 clear_cards(r);
4795 }
4796 }
4797
4798 void clear_cards(HeapRegion* r) {
4799 // Cards of the survivors should have already been dirtied.
4800 if (!r->is_survivor()) {
4801 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4802 }
4803 }
4804 };
4805
4806 class G1ParScrubRemSetTask: public AbstractGangTask {
4807 protected:
4808 G1RemSet* _g1rs;
4809 BitMap* _region_bm;
4810 BitMap* _card_bm;
4811 HeapRegionClaimer _hrclaimer;
4812
4813 public:
4814 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4815 AbstractGangTask("G1 ScrubRS"),
4816 _g1rs(g1_rs),
4817 _region_bm(region_bm),
4818 _card_bm(card_bm),
4819 _hrclaimer(num_workers) {
4820 }
4821
4822 void work(uint worker_id) {
4823 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4824 }
4825 };
4826
4827 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4828 uint num_workers = workers()->active_workers();
4829 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4830 workers()->run_task(&g1_par_scrub_rs_task);
4831 }
4832
4833 void G1CollectedHeap::cleanUpCardTable() {
4834 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4835 double start = os::elapsedTime();
4836
4837 {
4838 // Iterate over the dirty cards region list.
4839 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4840
4841 workers()->run_task(&cleanup_task);
4842 #ifndef PRODUCT
4843 _verifier->verify_card_table_cleanup();
4844 #endif
4845 }
4846
4847 double elapsed = os::elapsedTime() - start;
4848 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4849 }
4850
4851 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4852 size_t pre_used = 0;
4853 FreeRegionList local_free_list("Local List for CSet Freeing");
4854
4855 double young_time_ms = 0.0;
4856 double non_young_time_ms = 0.0;
4857
4858 // Since the collection set is a superset of the the young list,
4859 // all we need to do to clear the young list is clear its
4860 // head and length, and unlink any young regions in the code below
4861 _young_list->clear();
4862
4863 G1CollectorPolicy* policy = g1_policy();
4864
4865 double start_sec = os::elapsedTime();
4866 bool non_young = true;
4867
4868 HeapRegion* cur = cs_head;
4869 int age_bound = -1;
4870 size_t rs_lengths = 0;
4871
4872 while (cur != NULL) {
4873 assert(!is_on_master_free_list(cur), "sanity");
4874 if (non_young) {
4875 if (cur->is_young()) {
4876 double end_sec = os::elapsedTime();
4877 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4878 non_young_time_ms += elapsed_ms;
4879
4880 start_sec = os::elapsedTime();
4881 non_young = false;
4882 }
4883 } else {
4884 if (!cur->is_young()) {
4885 double end_sec = os::elapsedTime();
4886 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4887 young_time_ms += elapsed_ms;
4888
4889 start_sec = os::elapsedTime();
4890 non_young = true;
4891 }
4892 }
4893
4894 rs_lengths += cur->rem_set()->occupied_locked();
4895
4896 HeapRegion* next = cur->next_in_collection_set();
4897 assert(cur->in_collection_set(), "bad CS");
4898 cur->set_next_in_collection_set(NULL);
4899 clear_in_cset(cur);
4900
4901 if (cur->is_young()) {
4902 int index = cur->young_index_in_cset();
4903 assert(index != -1, "invariant");
4904 assert((uint) index < policy->young_cset_region_length(), "invariant");
4905 size_t words_survived = surviving_young_words[index];
4906 cur->record_surv_words_in_group(words_survived);
4907
4908 // At this point the we have 'popped' cur from the collection set
4909 // (linked via next_in_collection_set()) but it is still in the
4910 // young list (linked via next_young_region()). Clear the
4911 // _next_young_region field.
4912 cur->set_next_young_region(NULL);
4913 } else {
4914 int index = cur->young_index_in_cset();
4915 assert(index == -1, "invariant");
4916 }
4917
4918 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4919 (!cur->is_young() && cur->young_index_in_cset() == -1),
4920 "invariant" );
4921
4922 if (!cur->evacuation_failed()) {
4923 MemRegion used_mr = cur->used_region();
4924
4925 // And the region is empty.
4926 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4927 pre_used += cur->used();
4928 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4929 } else {
4930 cur->uninstall_surv_rate_group();
4931 if (cur->is_young()) {
4932 cur->set_young_index_in_cset(-1);
4933 }
4934 cur->set_evacuation_failed(false);
4935 // When moving a young gen region to old gen, we "allocate" that whole region
4936 // there. This is in addition to any already evacuated objects. Notify the
4937 // policy about that.
4938 // Old gen regions do not cause an additional allocation: both the objects
4939 // still in the region and the ones already moved are accounted for elsewhere.
4940 if (cur->is_young()) {
4941 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4942 }
4943 // The region is now considered to be old.
4944 cur->set_old();
4945 // Do some allocation statistics accounting. Regions that failed evacuation
4946 // are always made old, so there is no need to update anything in the young
4947 // gen statistics, but we need to update old gen statistics.
4948 size_t used_words = cur->marked_bytes() / HeapWordSize;
4949 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4950 _old_set.add(cur);
4951 evacuation_info.increment_collectionset_used_after(cur->used());
4952 }
4953 cur = next;
4954 }
4955
4956 evacuation_info.set_regions_freed(local_free_list.length());
4957 policy->record_max_rs_lengths(rs_lengths);
4958 policy->cset_regions_freed();
4959
4960 double end_sec = os::elapsedTime();
4961 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4962
4963 if (non_young) {
4964 non_young_time_ms += elapsed_ms;
4965 } else {
4966 young_time_ms += elapsed_ms;
4967 }
4968
4969 prepend_to_freelist(&local_free_list);
4970 decrement_summary_bytes(pre_used);
4971 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4972 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4973 }
4974
4975 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4976 private:
4977 FreeRegionList* _free_region_list;
4978 HeapRegionSet* _proxy_set;
4979 uint _humongous_regions_removed;
4980 size_t _freed_bytes;
4981 public:
4982
4983 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4984 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4985 }
4986
4987 virtual bool doHeapRegion(HeapRegion* r) {
4988 if (!r->is_starts_humongous()) {
4989 return false;
4990 }
4991
4992 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4993
4994 oop obj = (oop)r->bottom();
4995 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4996
4997 // The following checks whether the humongous object is live are sufficient.
4998 // The main additional check (in addition to having a reference from the roots
4999 // or the young gen) is whether the humongous object has a remembered set entry.
5000 //
5001 // A humongous object cannot be live if there is no remembered set for it
5002 // because:
5003 // - there can be no references from within humongous starts regions referencing
5004 // the object because we never allocate other objects into them.
5005 // (I.e. there are no intra-region references that may be missed by the
5006 // remembered set)
5007 // - as soon there is a remembered set entry to the humongous starts region
5008 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5009 // until the end of a concurrent mark.
5010 //
5011 // It is not required to check whether the object has been found dead by marking
5012 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5013 // all objects allocated during that time are considered live.
5014 // SATB marking is even more conservative than the remembered set.
5015 // So if at this point in the collection there is no remembered set entry,
5016 // nobody has a reference to it.
5017 // At the start of collection we flush all refinement logs, and remembered sets
5018 // are completely up-to-date wrt to references to the humongous object.
5019 //
5020 // Other implementation considerations:
5021 // - never consider object arrays at this time because they would pose
5022 // considerable effort for cleaning up the the remembered sets. This is
5023 // required because stale remembered sets might reference locations that
5024 // are currently allocated into.
5025 uint region_idx = r->hrm_index();
5026 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5027 !r->rem_set()->is_empty()) {
5028 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",
5029 region_idx,
5030 (size_t)obj->size() * HeapWordSize,
5031 p2i(r->bottom()),
5032 r->rem_set()->occupied(),
5033 r->rem_set()->strong_code_roots_list_length(),
5034 next_bitmap->isMarked(r->bottom()),
5035 g1h->is_humongous_reclaim_candidate(region_idx),
5036 obj->is_typeArray()
5037 );
5038 return false;
5039 }
5040
5041 guarantee(obj->is_typeArray(),
5042 "Only eagerly reclaiming type arrays is supported, but the object "
5043 PTR_FORMAT " is not.", p2i(r->bottom()));
5044
5045 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",
5046 region_idx,
5047 (size_t)obj->size() * HeapWordSize,
5048 p2i(r->bottom()),
5049 r->rem_set()->occupied(),
5050 r->rem_set()->strong_code_roots_list_length(),
5051 next_bitmap->isMarked(r->bottom()),
5052 g1h->is_humongous_reclaim_candidate(region_idx),
5053 obj->is_typeArray()
5054 );
5055
5056 // Need to clear mark bit of the humongous object if already set.
5057 if (next_bitmap->isMarked(r->bottom())) {
5058 next_bitmap->clear(r->bottom());
5059 }
5060 do {
5061 HeapRegion* next = g1h->next_region_in_humongous(r);
5062 _freed_bytes += r->used();
5063 r->set_containing_set(NULL);
5064 _humongous_regions_removed++;
5065 g1h->free_humongous_region(r, _free_region_list, false);
5066 r = next;
5067 } while (r != NULL);
5068
5069 return false;
5070 }
5071
5072 uint humongous_free_count() {
5073 return _humongous_regions_removed;
5074 }
5075
5076 size_t bytes_freed() const {
5077 return _freed_bytes;
5078 }
5079 };
5080
5081 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5082 assert_at_safepoint(true);
5083
5084 if (!G1EagerReclaimHumongousObjects ||
5085 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5086 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5087 return;
5088 }
5089
5090 double start_time = os::elapsedTime();
5091
5092 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5093
5094 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5095 heap_region_iterate(&cl);
5096
5097 remove_from_old_sets(0, cl.humongous_free_count());
5098
5099 G1HRPrinter* hrp = hr_printer();
5100 if (hrp->is_active()) {
5101 FreeRegionListIterator iter(&local_cleanup_list);
5102 while (iter.more_available()) {
5103 HeapRegion* hr = iter.get_next();
5104 hrp->cleanup(hr);
5105 }
5106 }
5107
5108 prepend_to_freelist(&local_cleanup_list);
5109 decrement_summary_bytes(cl.bytes_freed());
5110
5111 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5112 cl.humongous_free_count());
5113 }
5114
5115 // This routine is similar to the above but does not record
5116 // any policy statistics or update free lists; we are abandoning
5117 // the current incremental collection set in preparation of a
5118 // full collection. After the full GC we will start to build up
5119 // the incremental collection set again.
5120 // This is only called when we're doing a full collection
5121 // and is immediately followed by the tearing down of the young list.
5122
5123 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5124 HeapRegion* cur = cs_head;
5125
5126 while (cur != NULL) {
5127 HeapRegion* next = cur->next_in_collection_set();
5128 assert(cur->in_collection_set(), "bad CS");
5129 cur->set_next_in_collection_set(NULL);
5130 clear_in_cset(cur);
5131 cur->set_young_index_in_cset(-1);
5132 cur = next;
5133 }
5134 }
5135
5136 void G1CollectedHeap::set_free_regions_coming() {
5137 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5138
5139 assert(!free_regions_coming(), "pre-condition");
5140 _free_regions_coming = true;
5141 }
5142
5143 void G1CollectedHeap::reset_free_regions_coming() {
5144 assert(free_regions_coming(), "pre-condition");
5145
5146 {
5147 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5148 _free_regions_coming = false;
5149 SecondaryFreeList_lock->notify_all();
5150 }
5151
5152 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5153 }
5154
5155 void G1CollectedHeap::wait_while_free_regions_coming() {
5156 // Most of the time we won't have to wait, so let's do a quick test
5157 // first before we take the lock.
5158 if (!free_regions_coming()) {
5159 return;
5160 }
5161
5162 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5163
5164 {
5165 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5166 while (free_regions_coming()) {
5167 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5168 }
5169 }
5170
5171 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5172 }
5173
5174 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5175 return _allocator->is_retained_old_region(hr);
5176 }
5177
5178 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5179 _young_list->push_region(hr);
5180 }
5181
5182 class NoYoungRegionsClosure: public HeapRegionClosure {
5183 private:
5184 bool _success;
5185 public:
5186 NoYoungRegionsClosure() : _success(true) { }
5187 bool doHeapRegion(HeapRegion* r) {
5188 if (r->is_young()) {
5189 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5190 p2i(r->bottom()), p2i(r->end()));
5191 _success = false;
5192 }
5193 return false;
5194 }
5195 bool success() { return _success; }
5196 };
5197
5198 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5199 bool ret = _young_list->check_list_empty(check_sample);
5200
5201 if (check_heap) {
5202 NoYoungRegionsClosure closure;
5203 heap_region_iterate(&closure);
5204 ret = ret && closure.success();
5205 }
5206
5207 return ret;
5208 }
5209
5210 class TearDownRegionSetsClosure : public HeapRegionClosure {
5211 private:
5212 HeapRegionSet *_old_set;
5213
5214 public:
5215 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5216
5217 bool doHeapRegion(HeapRegion* r) {
5218 if (r->is_old()) {
5219 _old_set->remove(r);
5220 } else {
5221 // We ignore free regions, we'll empty the free list afterwards.
5222 // We ignore young regions, we'll empty the young list afterwards.
5223 // We ignore humongous regions, we're not tearing down the
5224 // humongous regions set.
5225 assert(r->is_free() || r->is_young() || r->is_humongous(),
5226 "it cannot be another type");
5227 }
5228 return false;
5229 }
5230
5231 ~TearDownRegionSetsClosure() {
5232 assert(_old_set->is_empty(), "post-condition");
5233 }
5234 };
5235
5236 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5237 assert_at_safepoint(true /* should_be_vm_thread */);
5238
5239 if (!free_list_only) {
5240 TearDownRegionSetsClosure cl(&_old_set);
5241 heap_region_iterate(&cl);
5242
5243 // Note that emptying the _young_list is postponed and instead done as
5244 // the first step when rebuilding the regions sets again. The reason for
5245 // this is that during a full GC string deduplication needs to know if
5246 // a collected region was young or old when the full GC was initiated.
5247 }
5248 _hrm.remove_all_free_regions();
5249 }
5250
5251 void G1CollectedHeap::increase_used(size_t bytes) {
5252 _summary_bytes_used += bytes;
5253 }
5254
5255 void G1CollectedHeap::decrease_used(size_t bytes) {
5256 assert(_summary_bytes_used >= bytes,
5257 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5258 _summary_bytes_used, bytes);
5259 _summary_bytes_used -= bytes;
5260 }
5261
5262 void G1CollectedHeap::set_used(size_t bytes) {
5263 _summary_bytes_used = bytes;
5264 }
5265
5266 class RebuildRegionSetsClosure : public HeapRegionClosure {
5267 private:
5268 bool _free_list_only;
5269 HeapRegionSet* _old_set;
5270 HeapRegionManager* _hrm;
5271 size_t _total_used;
5272
5273 public:
5274 RebuildRegionSetsClosure(bool free_list_only,
5275 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5276 _free_list_only(free_list_only),
5277 _old_set(old_set), _hrm(hrm), _total_used(0) {
5278 assert(_hrm->num_free_regions() == 0, "pre-condition");
5279 if (!free_list_only) {
5280 assert(_old_set->is_empty(), "pre-condition");
5281 }
5282 }
5283
5284 bool doHeapRegion(HeapRegion* r) {
5285 if (r->is_empty()) {
5286 // Add free regions to the free list
5287 r->set_free();
5288 r->set_allocation_context(AllocationContext::system());
5289 _hrm->insert_into_free_list(r);
5290 } else if (!_free_list_only) {
5291 assert(!r->is_young(), "we should not come across young regions");
5292
5293 if (r->is_humongous()) {
5294 // We ignore humongous regions. We left the humongous set unchanged.
5295 } else {
5296 // Objects that were compacted would have ended up on regions
5297 // that were previously old or free. Archive regions (which are
5298 // old) will not have been touched.
5299 assert(r->is_free() || r->is_old(), "invariant");
5300 // We now consider them old, so register as such. Leave
5301 // archive regions set that way, however, while still adding
5302 // them to the old set.
5303 if (!r->is_archive()) {
5304 r->set_old();
5305 }
5306 _old_set->add(r);
5307 }
5308 _total_used += r->used();
5309 }
5310
5311 return false;
5312 }
5313
5314 size_t total_used() {
5315 return _total_used;
5316 }
5317 };
5318
5319 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5320 assert_at_safepoint(true /* should_be_vm_thread */);
5321
5322 if (!free_list_only) {
5323 _young_list->empty_list();
5324 }
5325
5326 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5327 heap_region_iterate(&cl);
5328
5329 if (!free_list_only) {
5330 set_used(cl.total_used());
5331 if (_archive_allocator != NULL) {
5332 _archive_allocator->clear_used();
5333 }
5334 }
5335 assert(used_unlocked() == recalculate_used(),
5336 "inconsistent used_unlocked(), "
5337 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5338 used_unlocked(), recalculate_used());
5339 }
5340
5341 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5342 _refine_cte_cl->set_concurrent(concurrent);
5343 }
5344
5345 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5346 HeapRegion* hr = heap_region_containing(p);
5347 return hr->is_in(p);
5348 }
5349
5350 // Methods for the mutator alloc region
5351
5352 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5353 bool force) {
5354 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5355 assert(!force || g1_policy()->can_expand_young_list(),
5356 "if force is true we should be able to expand the young list");
5357 bool young_list_full = g1_policy()->is_young_list_full();
5358 if (force || !young_list_full) {
5359 HeapRegion* new_alloc_region = new_region(word_size,
5360 false /* is_old */,
5361 false /* do_expand */);
5362 if (new_alloc_region != NULL) {
5363 set_region_short_lived_locked(new_alloc_region);
5364 _hr_printer.alloc(new_alloc_region, young_list_full);
5365 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5366 return new_alloc_region;
5367 }
5368 }
5369 return NULL;
5370 }
5371
5372 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5373 size_t allocated_bytes) {
5374 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5375 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5376
5377 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5378 increase_used(allocated_bytes);
5379 _hr_printer.retire(alloc_region);
5380 // We update the eden sizes here, when the region is retired,
5381 // instead of when it's allocated, since this is the point that its
5382 // used space has been recored in _summary_bytes_used.
5383 g1mm()->update_eden_size();
5384 }
5385
5386 // Methods for the GC alloc regions
5387
5388 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5389 uint count,
5390 InCSetState dest) {
5391 assert(FreeList_lock->owned_by_self(), "pre-condition");
5392
5393 if (count < g1_policy()->max_regions(dest)) {
5394 const bool is_survivor = (dest.is_young());
5395 HeapRegion* new_alloc_region = new_region(word_size,
5396 !is_survivor,
5397 true /* do_expand */);
5398 if (new_alloc_region != NULL) {
5399 // We really only need to do this for old regions given that we
5400 // should never scan survivors. But it doesn't hurt to do it
5401 // for survivors too.
5402 new_alloc_region->record_timestamp();
5403 if (is_survivor) {
5404 new_alloc_region->set_survivor();
5405 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5406 } else {
5407 new_alloc_region->set_old();
5408 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5409 }
5410 _hr_printer.alloc(new_alloc_region);
5411 bool during_im = collector_state()->during_initial_mark_pause();
5412 new_alloc_region->note_start_of_copying(during_im);
5413 return new_alloc_region;
5414 }
5415 }
5416 return NULL;
5417 }
5418
5419 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5420 size_t allocated_bytes,
5421 InCSetState dest) {
5422 bool during_im = collector_state()->during_initial_mark_pause();
5423 alloc_region->note_end_of_copying(during_im);
5424 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5425 if (dest.is_young()) {
5426 young_list()->add_survivor_region(alloc_region);
5427 } else {
5428 _old_set.add(alloc_region);
5429 }
5430 _hr_printer.retire(alloc_region);
5431 }
5432
5433 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5434 bool expanded = false;
5435 uint index = _hrm.find_highest_free(&expanded);
5436
5437 if (index != G1_NO_HRM_INDEX) {
5438 if (expanded) {
5439 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5440 HeapRegion::GrainWords * HeapWordSize);
5441 }
5442 _hrm.allocate_free_regions_starting_at(index, 1);
5443 return region_at(index);
5444 }
5445 return NULL;
5446 }
5447
5448 // Optimized nmethod scanning
5449
5450 class RegisterNMethodOopClosure: public OopClosure {
5451 G1CollectedHeap* _g1h;
5452 nmethod* _nm;
5453
5454 template <class T> void do_oop_work(T* p) {
5455 T heap_oop = oopDesc::load_heap_oop(p);
5456 if (!oopDesc::is_null(heap_oop)) {
5457 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5458 HeapRegion* hr = _g1h->heap_region_containing(obj);
5459 assert(!hr->is_continues_humongous(),
5460 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5461 " starting at " HR_FORMAT,
5462 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5463
5464 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5465 hr->add_strong_code_root_locked(_nm);
5466 }
5467 }
5468
5469 public:
5470 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5471 _g1h(g1h), _nm(nm) {}
5472
5473 void do_oop(oop* p) { do_oop_work(p); }
5474 void do_oop(narrowOop* p) { do_oop_work(p); }
5475 };
5476
5477 class UnregisterNMethodOopClosure: public OopClosure {
5478 G1CollectedHeap* _g1h;
5479 nmethod* _nm;
5480
5481 template <class T> void do_oop_work(T* p) {
5482 T heap_oop = oopDesc::load_heap_oop(p);
5483 if (!oopDesc::is_null(heap_oop)) {
5484 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5485 HeapRegion* hr = _g1h->heap_region_containing(obj);
5486 assert(!hr->is_continues_humongous(),
5487 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5488 " starting at " HR_FORMAT,
5489 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5490
5491 hr->remove_strong_code_root(_nm);
5492 }
5493 }
5494
5495 public:
5496 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5497 _g1h(g1h), _nm(nm) {}
5498
5499 void do_oop(oop* p) { do_oop_work(p); }
5500 void do_oop(narrowOop* p) { do_oop_work(p); }
5501 };
5502
5503 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5504 CollectedHeap::register_nmethod(nm);
5505
5506 guarantee(nm != NULL, "sanity");
5507 RegisterNMethodOopClosure reg_cl(this, nm);
5508 nm->oops_do(®_cl);
5509 }
5510
5511 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5512 CollectedHeap::unregister_nmethod(nm);
5513
5514 guarantee(nm != NULL, "sanity");
5515 UnregisterNMethodOopClosure reg_cl(this, nm);
5516 nm->oops_do(®_cl, true);
5517 }
5518
5519 void G1CollectedHeap::purge_code_root_memory() {
5520 double purge_start = os::elapsedTime();
5521 G1CodeRootSet::purge();
5522 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5523 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5524 }
5525
5526 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5527 G1CollectedHeap* _g1h;
5528
5529 public:
5530 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5531 _g1h(g1h) {}
5532
5533 void do_code_blob(CodeBlob* cb) {
5534 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5535 if (nm == NULL) {
5536 return;
5537 }
5538
5539 if (ScavengeRootsInCode) {
5540 _g1h->register_nmethod(nm);
5541 }
5542 }
5543 };
5544
5545 void G1CollectedHeap::rebuild_strong_code_roots() {
5546 RebuildStrongCodeRootClosure blob_cl(this);
5547 CodeCache::blobs_do(&blob_cl);
5548 }