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