1 /*
2 * Copyright (c) 2001, 2015, 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 "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootClosures.hpp"
48 #include "gc/g1/g1RootProcessor.hpp"
49 #include "gc/g1/g1StringDedup.hpp"
50 #include "gc/g1/g1YCTypes.hpp"
51 #include "gc/g1/heapRegion.inline.hpp"
52 #include "gc/g1/heapRegionRemSet.hpp"
53 #include "gc/g1/heapRegionSet.inline.hpp"
54 #include "gc/g1/suspendibleThreadSet.hpp"
55 #include "gc/g1/vm_operations_g1.hpp"
56 #include "gc/shared/gcHeapSummary.hpp"
57 #include "gc/shared/gcId.hpp"
58 #include "gc/shared/gcLocker.inline.hpp"
59 #include "gc/shared/gcTimer.hpp"
60 #include "gc/shared/gcTrace.hpp"
61 #include "gc/shared/gcTraceTime.hpp"
62 #include "gc/shared/generationSpec.hpp"
63 #include "gc/shared/isGCActiveMark.hpp"
64 #include "gc/shared/referenceProcessor.hpp"
65 #include "gc/shared/taskqueue.inline.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_processed;
116
117 public:
118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
119
120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
121 *card_ptr = CardTableModRefBS::dirty_card_val();
122 _num_processed++;
123 return true;
124 }
125
126 size_t num_processed() const { return _num_processed; }
127 };
128
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
141 {
142 // Claim the right to put the region on the dirty cards region list
143 // by installing a self pointer.
144 HeapRegion* next = hr->get_next_dirty_cards_region();
145 if (next == NULL) {
146 HeapRegion* res = (HeapRegion*)
147 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
148 NULL);
149 if (res == NULL) {
150 HeapRegion* head;
151 do {
152 // Put the region to the dirty cards region list.
153 head = _dirty_cards_region_list;
154 next = (HeapRegion*)
155 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
156 if (next == head) {
157 assert(hr->get_next_dirty_cards_region() == hr,
158 "hr->get_next_dirty_cards_region() != hr");
159 if (next == NULL) {
160 // The last region in the list points to itself.
161 hr->set_next_dirty_cards_region(hr);
162 } else {
163 hr->set_next_dirty_cards_region(next);
164 }
165 }
166 } while (next != head);
167 }
168 }
169 }
170
171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
172 {
173 HeapRegion* head;
174 HeapRegion* hr;
175 do {
176 head = _dirty_cards_region_list;
177 if (head == NULL) {
178 return NULL;
179 }
180 HeapRegion* new_head = head->get_next_dirty_cards_region();
181 if (head == new_head) {
182 // The last region.
183 new_head = NULL;
184 }
185 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
186 head);
187 } while (hr != head);
188 assert(hr != NULL, "invariant");
189 hr->set_next_dirty_cards_region(NULL);
190 return hr;
191 }
192
193 // Returns true if the reference points to an object that
194 // can move in an incremental collection.
195 bool G1CollectedHeap::is_scavengable(const void* p) {
196 HeapRegion* hr = heap_region_containing(p);
197 return !hr->is_pinned();
198 }
199
200 // Private methods.
201
202 HeapRegion*
203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
205 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
206 if (!_secondary_free_list.is_empty()) {
207 if (G1ConcRegionFreeingVerbose) {
208 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
209 "secondary_free_list has %u entries",
210 _secondary_free_list.length());
211 }
212 // It looks as if there are free regions available on the
213 // secondary_free_list. Let's move them to the free_list and try
214 // again to allocate from it.
215 append_secondary_free_list();
216
217 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
218 "empty we should have moved at least one entry to the free_list");
219 HeapRegion* res = _hrm.allocate_free_region(is_old);
220 if (G1ConcRegionFreeingVerbose) {
221 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
222 "allocated " HR_FORMAT " from secondary_free_list",
223 HR_FORMAT_PARAMS(res));
224 }
225 return res;
226 }
227
228 // Wait here until we get notified either when (a) there are no
229 // more free regions coming or (b) some regions have been moved on
230 // the secondary_free_list.
231 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
232 }
233
234 if (G1ConcRegionFreeingVerbose) {
235 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
236 "could not allocate from secondary_free_list");
237 }
238 return NULL;
239 }
240
241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
242 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
243 "the only time we use this to allocate a humongous region is "
244 "when we are allocating a single humongous region");
245
246 HeapRegion* res;
247 if (G1StressConcRegionFreeing) {
248 if (!_secondary_free_list.is_empty()) {
249 if (G1ConcRegionFreeingVerbose) {
250 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
251 "forced to look at the secondary_free_list");
252 }
253 res = new_region_try_secondary_free_list(is_old);
254 if (res != NULL) {
255 return res;
256 }
257 }
258 }
259
260 res = _hrm.allocate_free_region(is_old);
261
262 if (res == NULL) {
263 if (G1ConcRegionFreeingVerbose) {
264 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
265 "res == NULL, trying the secondary_free_list");
266 }
267 res = new_region_try_secondary_free_list(is_old);
268 }
269 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
270 // Currently, only attempts to allocate GC alloc regions set
271 // do_expand to true. So, we should only reach here during a
272 // safepoint. If this assumption changes we might have to
273 // reconsider the use of _expand_heap_after_alloc_failure.
274 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
275
276 ergo_verbose1(ErgoHeapSizing,
277 "attempt heap expansion",
278 ergo_format_reason("region allocation request failed")
279 ergo_format_byte("allocation request"),
280 word_size * HeapWordSize);
281 if (expand(word_size * HeapWordSize)) {
282 // Given that expand() succeeded in expanding the heap, and we
283 // always expand the heap by an amount aligned to the heap
284 // region size, the free list should in theory not be empty.
285 // In either case allocate_free_region() will check for NULL.
286 res = _hrm.allocate_free_region(is_old);
287 } else {
288 _expand_heap_after_alloc_failure = false;
289 }
290 }
291 return res;
292 }
293
294 HeapWord*
295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
296 uint num_regions,
297 size_t word_size,
298 AllocationContext_t context) {
299 assert(first != G1_NO_HRM_INDEX, "pre-condition");
300 assert(is_humongous(word_size), "word_size should be humongous");
301 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
302
303 // Index of last region in the series.
304 uint last = first + num_regions - 1;
305
306 // We need to initialize the region(s) we just discovered. This is
307 // a bit tricky given that it can happen concurrently with
308 // refinement threads refining cards on these regions and
309 // potentially wanting to refine the BOT as they are scanning
310 // those cards (this can happen shortly after a cleanup; see CR
311 // 6991377). So we have to set up the region(s) carefully and in
312 // a specific order.
313
314 // The word size sum of all the regions we will allocate.
315 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
316 assert(word_size <= word_size_sum, "sanity");
317
318 // This will be the "starts humongous" region.
319 HeapRegion* first_hr = region_at(first);
320 // The header of the new object will be placed at the bottom of
321 // the first region.
322 HeapWord* new_obj = first_hr->bottom();
323 // This will be the new top of the new object.
324 HeapWord* obj_top = new_obj + word_size;
325
326 // First, we need to zero the header of the space that we will be
327 // allocating. When we update top further down, some refinement
328 // threads might try to scan the region. By zeroing the header we
329 // ensure that any thread that will try to scan the region will
330 // come across the zero klass word and bail out.
331 //
332 // NOTE: It would not have been correct to have used
333 // CollectedHeap::fill_with_object() and make the space look like
334 // an int array. The thread that is doing the allocation will
335 // later update the object header to a potentially different array
336 // type and, for a very short period of time, the klass and length
337 // fields will be inconsistent. This could cause a refinement
338 // thread to calculate the object size incorrectly.
339 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
340
341 // How many words we use for filler objects.
342 size_t word_fill_size = word_size_sum - word_size;
343
344 // How many words memory we "waste" which cannot hold a filler object.
345 size_t words_not_fillable = 0;
346
347 if (word_fill_size >= min_fill_size()) {
348 fill_with_objects(obj_top, word_fill_size);
349 } else if (word_fill_size > 0) {
350 // We have space to fill, but we cannot fit an object there.
351 words_not_fillable = word_fill_size;
352 word_fill_size = 0;
353 }
354
355 // We will set up the first region as "starts humongous". This
356 // will also update the BOT covering all the regions to reflect
357 // that there is a single object that starts at the bottom of the
358 // first region.
359 first_hr->set_starts_humongous(obj_top, word_fill_size);
360 first_hr->set_allocation_context(context);
361 // Then, if there are any, we will set up the "continues
362 // humongous" regions.
363 HeapRegion* hr = NULL;
364 for (uint i = first + 1; i <= last; ++i) {
365 hr = region_at(i);
366 hr->set_continues_humongous(first_hr);
367 hr->set_allocation_context(context);
368 }
369
370 // Up to this point no concurrent thread would have been able to
371 // do any scanning on any region in this series. All the top
372 // fields still point to bottom, so the intersection between
373 // [bottom,top] and [card_start,card_end] will be empty. Before we
374 // update the top fields, we'll do a storestore to make sure that
375 // no thread sees the update to top before the zeroing of the
376 // object header and the BOT initialization.
377 OrderAccess::storestore();
378
379 // Now, we will update the top fields of the "continues humongous"
380 // regions except the last one.
381 for (uint i = first; i < last; ++i) {
382 hr = region_at(i);
383 hr->set_top(hr->end());
384 }
385
386 hr = region_at(last);
387 // If we cannot fit a filler object, we must set top to the end
388 // of the humongous object, otherwise we cannot iterate the heap
389 // and the BOT will not be complete.
390 hr->set_top(hr->end() - words_not_fillable);
391
392 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
393 "obj_top should be in last region");
394
395 check_bitmaps("Humongous Region Allocation", first_hr);
396
397 assert(words_not_fillable == 0 ||
398 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
399 "Miscalculation in humongous allocation");
400
401 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
402
403 for (uint i = first; i <= last; ++i) {
404 hr = region_at(i);
405 _humongous_set.add(hr);
406 if (i == first) {
407 _hr_printer.alloc(G1HRPrinter::StartsHumongous, hr, hr->top());
408 } else {
409 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->top());
410 }
411 }
412
413 return new_obj;
414 }
415
416 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
417 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
418 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
419 }
420
421 // If could fit into free regions w/o expansion, try.
422 // Otherwise, if can expand, do so.
423 // Otherwise, if using ex regions might help, try with ex given back.
424 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
425 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
426
427 verify_region_sets_optional();
428
429 uint first = G1_NO_HRM_INDEX;
430 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
431
432 if (obj_regions == 1) {
433 // Only one region to allocate, try to use a fast path by directly allocating
434 // from the free lists. Do not try to expand here, we will potentially do that
435 // later.
436 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
437 if (hr != NULL) {
438 first = hr->hrm_index();
439 }
440 } else {
441 // We can't allocate humongous regions spanning more than one region while
442 // cleanupComplete() is running, since some of the regions we find to be
443 // empty might not yet be added to the free list. It is not straightforward
444 // to know in which list they are on so that we can remove them. We only
445 // need to do this if we need to allocate more than one region to satisfy the
446 // current humongous allocation request. If we are only allocating one region
447 // we use the one-region region allocation code (see above), that already
448 // potentially waits for regions from the secondary free list.
449 wait_while_free_regions_coming();
450 append_secondary_free_list_if_not_empty_with_lock();
451
452 // Policy: Try only empty regions (i.e. already committed first). Maybe we
453 // are lucky enough to find some.
454 first = _hrm.find_contiguous_only_empty(obj_regions);
455 if (first != G1_NO_HRM_INDEX) {
456 _hrm.allocate_free_regions_starting_at(first, obj_regions);
457 }
458 }
459
460 if (first == G1_NO_HRM_INDEX) {
461 // Policy: We could not find enough regions for the humongous object in the
462 // free list. Look through the heap to find a mix of free and uncommitted regions.
463 // If so, try expansion.
464 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
465 if (first != G1_NO_HRM_INDEX) {
466 // We found something. Make sure these regions are committed, i.e. expand
467 // the heap. Alternatively we could do a defragmentation GC.
468 ergo_verbose1(ErgoHeapSizing,
469 "attempt heap expansion",
470 ergo_format_reason("humongous allocation request failed")
471 ergo_format_byte("allocation request"),
472 word_size * HeapWordSize);
473
474 _hrm.expand_at(first, obj_regions);
475 g1_policy()->record_new_heap_size(num_regions());
476
477 #ifdef ASSERT
478 for (uint i = first; i < first + obj_regions; ++i) {
479 HeapRegion* hr = region_at(i);
480 assert(hr->is_free(), "sanity");
481 assert(hr->is_empty(), "sanity");
482 assert(is_on_master_free_list(hr), "sanity");
483 }
484 #endif
485 _hrm.allocate_free_regions_starting_at(first, obj_regions);
486 } else {
487 // Policy: Potentially trigger a defragmentation GC.
488 }
489 }
490
491 HeapWord* result = NULL;
492 if (first != G1_NO_HRM_INDEX) {
493 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
494 word_size, context);
495 assert(result != NULL, "it should always return a valid result");
496
497 // A successful humongous object allocation changes the used space
498 // information of the old generation so we need to recalculate the
499 // sizes and update the jstat counters here.
500 g1mm()->update_sizes();
501 }
502
503 verify_region_sets_optional();
504
505 return result;
506 }
507
508 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
509 assert_heap_not_locked_and_not_at_safepoint();
510 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
511
512 uint dummy_gc_count_before;
513 uint dummy_gclocker_retry_count = 0;
514 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
515 }
516
517 HeapWord*
518 G1CollectedHeap::mem_allocate(size_t word_size,
519 bool* gc_overhead_limit_was_exceeded) {
520 assert_heap_not_locked_and_not_at_safepoint();
521
522 // Loop until the allocation is satisfied, or unsatisfied after GC.
523 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
524 uint gc_count_before;
525
526 HeapWord* result = NULL;
527 if (!is_humongous(word_size)) {
528 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
529 } else {
530 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
531 }
532 if (result != NULL) {
533 return result;
534 }
535
536 // Create the garbage collection operation...
537 VM_G1CollectForAllocation op(gc_count_before, word_size);
538 op.set_allocation_context(AllocationContext::current());
539
540 // ...and get the VM thread to execute it.
541 VMThread::execute(&op);
542
543 if (op.prologue_succeeded() && op.pause_succeeded()) {
544 // If the operation was successful we'll return the result even
545 // if it is NULL. If the allocation attempt failed immediately
546 // after a Full GC, it's unlikely we'll be able to allocate now.
547 HeapWord* result = op.result();
548 if (result != NULL && !is_humongous(word_size)) {
549 // Allocations that take place on VM operations do not do any
550 // card dirtying and we have to do it here. We only have to do
551 // this for non-humongous allocations, though.
552 dirty_young_block(result, word_size);
553 }
554 return result;
555 } else {
556 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
557 return NULL;
558 }
559 assert(op.result() == NULL,
560 "the result should be NULL if the VM op did not succeed");
561 }
562
563 // Give a warning if we seem to be looping forever.
564 if ((QueuedAllocationWarningCount > 0) &&
565 (try_count % QueuedAllocationWarningCount == 0)) {
566 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
567 }
568 }
569
570 ShouldNotReachHere();
571 return NULL;
572 }
573
574 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
575 AllocationContext_t context,
576 uint* gc_count_before_ret,
577 uint* gclocker_retry_count_ret) {
578 // Make sure you read the note in attempt_allocation_humongous().
579
580 assert_heap_not_locked_and_not_at_safepoint();
581 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
582 "be called for humongous allocation requests");
583
584 // We should only get here after the first-level allocation attempt
585 // (attempt_allocation()) failed to allocate.
586
587 // We will loop until a) we manage to successfully perform the
588 // allocation or b) we successfully schedule a collection which
589 // fails to perform the allocation. b) is the only case when we'll
590 // return NULL.
591 HeapWord* result = NULL;
592 for (int try_count = 1; /* we'll return */; try_count += 1) {
593 bool should_try_gc;
594 uint gc_count_before;
595
596 {
597 MutexLockerEx x(Heap_lock);
598 result = _allocator->attempt_allocation_locked(word_size, context);
599 if (result != NULL) {
600 return result;
601 }
602
603 if (GC_locker::is_active_and_needs_gc()) {
604 if (g1_policy()->can_expand_young_list()) {
605 // No need for an ergo verbose message here,
606 // can_expand_young_list() does this when it returns true.
607 result = _allocator->attempt_allocation_force(word_size, context);
608 if (result != NULL) {
609 return result;
610 }
611 }
612 should_try_gc = false;
613 } else {
614 // The GCLocker may not be active but the GCLocker initiated
615 // GC may not yet have been performed (GCLocker::needs_gc()
616 // returns true). In this case we do not try this GC and
617 // wait until the GCLocker initiated GC is performed, and
618 // then retry the allocation.
619 if (GC_locker::needs_gc()) {
620 should_try_gc = false;
621 } else {
622 // Read the GC count while still holding the Heap_lock.
623 gc_count_before = total_collections();
624 should_try_gc = true;
625 }
626 }
627 }
628
629 if (should_try_gc) {
630 bool succeeded;
631 result = do_collection_pause(word_size, gc_count_before, &succeeded,
632 GCCause::_g1_inc_collection_pause);
633 if (result != NULL) {
634 assert(succeeded, "only way to get back a non-NULL result");
635 return result;
636 }
637
638 if (succeeded) {
639 // If we get here we successfully scheduled a collection which
640 // failed to allocate. No point in trying to allocate
641 // further. We'll just return NULL.
642 MutexLockerEx x(Heap_lock);
643 *gc_count_before_ret = total_collections();
644 return NULL;
645 }
646 } else {
647 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
648 MutexLockerEx x(Heap_lock);
649 *gc_count_before_ret = total_collections();
650 return NULL;
651 }
652 // The GCLocker is either active or the GCLocker initiated
653 // GC has not yet been performed. Stall until it is and
654 // then retry the allocation.
655 GC_locker::stall_until_clear();
656 (*gclocker_retry_count_ret) += 1;
657 }
658
659 // We can reach here if we were unsuccessful in scheduling a
660 // collection (because another thread beat us to it) or if we were
661 // stalled due to the GC locker. In either can we should retry the
662 // allocation attempt in case another thread successfully
663 // performed a collection and reclaimed enough space. We do the
664 // first attempt (without holding the Heap_lock) here and the
665 // follow-on attempt will be at the start of the next loop
666 // iteration (after taking the Heap_lock).
667 result = _allocator->attempt_allocation(word_size, context);
668 if (result != NULL) {
669 return result;
670 }
671
672 // Give a warning if we seem to be looping forever.
673 if ((QueuedAllocationWarningCount > 0) &&
674 (try_count % QueuedAllocationWarningCount == 0)) {
675 warning("G1CollectedHeap::attempt_allocation_slow() "
676 "retries %d times", try_count);
677 }
678 }
679
680 ShouldNotReachHere();
681 return NULL;
682 }
683
684 void G1CollectedHeap::begin_archive_alloc_range() {
685 assert_at_safepoint(true /* should_be_vm_thread */);
686 if (_archive_allocator == NULL) {
687 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
688 }
689 }
690
691 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
692 // Allocations in archive regions cannot be of a size that would be considered
693 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
694 // may be different at archive-restore time.
695 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
696 }
697
698 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
699 assert_at_safepoint(true /* should_be_vm_thread */);
700 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
701 if (is_archive_alloc_too_large(word_size)) {
702 return NULL;
703 }
704 return _archive_allocator->archive_mem_allocate(word_size);
705 }
706
707 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
708 size_t end_alignment_in_bytes) {
709 assert_at_safepoint(true /* should_be_vm_thread */);
710 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
711
712 // Call complete_archive to do the real work, filling in the MemRegion
713 // array with the archive regions.
714 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
715 delete _archive_allocator;
716 _archive_allocator = NULL;
717 }
718
719 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
720 assert(ranges != NULL, "MemRegion array NULL");
721 assert(count != 0, "No MemRegions provided");
722 MemRegion reserved = _hrm.reserved();
723 for (size_t i = 0; i < count; i++) {
724 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
725 return false;
726 }
727 }
728 return true;
729 }
730
731 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
732 assert(!is_init_completed(), "Expect to be called at JVM init time");
733 assert(ranges != NULL, "MemRegion array NULL");
734 assert(count != 0, "No MemRegions provided");
735 MutexLockerEx x(Heap_lock);
736
737 MemRegion reserved = _hrm.reserved();
738 HeapWord* prev_last_addr = NULL;
739 HeapRegion* prev_last_region = NULL;
740
741 // Temporarily disable pretouching of heap pages. This interface is used
742 // when mmap'ing archived heap data in, so pre-touching is wasted.
743 FlagSetting fs(AlwaysPreTouch, false);
744
745 // Enable archive object checking in G1MarkSweep. We have to let it know
746 // about each archive range, so that objects in those ranges aren't marked.
747 G1MarkSweep::enable_archive_object_check();
748
749 // For each specified MemRegion range, allocate the corresponding G1
750 // regions and mark them as archive regions. We expect the ranges in
751 // ascending starting address order, without overlap.
752 for (size_t i = 0; i < count; i++) {
753 MemRegion curr_range = ranges[i];
754 HeapWord* start_address = curr_range.start();
755 size_t word_size = curr_range.word_size();
756 HeapWord* last_address = curr_range.last();
757 size_t commits = 0;
758
759 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
760 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
761 p2i(start_address), p2i(last_address));
762 guarantee(start_address > prev_last_addr,
763 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
764 p2i(start_address), p2i(prev_last_addr));
765 prev_last_addr = last_address;
766
767 // Check for ranges that start in the same G1 region in which the previous
768 // range ended, and adjust the start address so we don't try to allocate
769 // the same region again. If the current range is entirely within that
770 // region, skip it, just adjusting the recorded top.
771 HeapRegion* start_region = _hrm.addr_to_region(start_address);
772 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
773 start_address = start_region->end();
774 if (start_address > last_address) {
775 increase_used(word_size * HeapWordSize);
776 start_region->set_top(last_address + 1);
777 continue;
778 }
779 start_region->set_top(start_address);
780 curr_range = MemRegion(start_address, last_address + 1);
781 start_region = _hrm.addr_to_region(start_address);
782 }
783
784 // Perform the actual region allocation, exiting if it fails.
785 // Then note how much new space we have allocated.
786 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
787 return false;
788 }
789 increase_used(word_size * HeapWordSize);
790 if (commits != 0) {
791 ergo_verbose1(ErgoHeapSizing,
792 "attempt heap expansion",
793 ergo_format_reason("allocate archive regions")
794 ergo_format_byte("total size"),
795 HeapRegion::GrainWords * HeapWordSize * commits);
796 }
797
798 // Mark each G1 region touched by the range as archive, add it to the old set,
799 // and set the allocation context and top.
800 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
801 HeapRegion* last_region = _hrm.addr_to_region(last_address);
802 prev_last_region = last_region;
803
804 while (curr_region != NULL) {
805 assert(curr_region->is_empty() && !curr_region->is_pinned(),
806 "Region already in use (index %u)", curr_region->hrm_index());
807 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
808 curr_region->set_allocation_context(AllocationContext::system());
809 curr_region->set_archive();
810 _old_set.add(curr_region);
811 if (curr_region != last_region) {
812 curr_region->set_top(curr_region->end());
813 curr_region = _hrm.next_region_in_heap(curr_region);
814 } else {
815 curr_region->set_top(last_address + 1);
816 curr_region = NULL;
817 }
818 }
819
820 // Notify mark-sweep of the archive range.
821 G1MarkSweep::set_range_archive(curr_range, true);
822 }
823 return true;
824 }
825
826 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
827 assert(!is_init_completed(), "Expect to be called at JVM init time");
828 assert(ranges != NULL, "MemRegion array NULL");
829 assert(count != 0, "No MemRegions provided");
830 MemRegion reserved = _hrm.reserved();
831 HeapWord *prev_last_addr = NULL;
832 HeapRegion* prev_last_region = NULL;
833
834 // For each MemRegion, create filler objects, if needed, in the G1 regions
835 // that contain the address range. The address range actually within the
836 // MemRegion will not be modified. That is assumed to have been initialized
837 // elsewhere, probably via an mmap of archived heap data.
838 MutexLockerEx x(Heap_lock);
839 for (size_t i = 0; i < count; i++) {
840 HeapWord* start_address = ranges[i].start();
841 HeapWord* last_address = ranges[i].last();
842
843 assert(reserved.contains(start_address) && reserved.contains(last_address),
844 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
845 p2i(start_address), p2i(last_address));
846 assert(start_address > prev_last_addr,
847 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
848 p2i(start_address), p2i(prev_last_addr));
849
850 HeapRegion* start_region = _hrm.addr_to_region(start_address);
851 HeapRegion* last_region = _hrm.addr_to_region(last_address);
852 HeapWord* bottom_address = start_region->bottom();
853
854 // Check for a range beginning in the same region in which the
855 // previous one ended.
856 if (start_region == prev_last_region) {
857 bottom_address = prev_last_addr + 1;
858 }
859
860 // Verify that the regions were all marked as archive regions by
861 // alloc_archive_regions.
862 HeapRegion* curr_region = start_region;
863 while (curr_region != NULL) {
864 guarantee(curr_region->is_archive(),
865 "Expected archive region at index %u", curr_region->hrm_index());
866 if (curr_region != last_region) {
867 curr_region = _hrm.next_region_in_heap(curr_region);
868 } else {
869 curr_region = NULL;
870 }
871 }
872
873 prev_last_addr = last_address;
874 prev_last_region = last_region;
875
876 // Fill the memory below the allocated range with dummy object(s),
877 // if the region bottom does not match the range start, or if the previous
878 // range ended within the same G1 region, and there is a gap.
879 if (start_address != bottom_address) {
880 size_t fill_size = pointer_delta(start_address, bottom_address);
881 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
882 increase_used(fill_size * HeapWordSize);
883 }
884 }
885 }
886
887 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
888 uint* gc_count_before_ret,
889 uint* gclocker_retry_count_ret) {
890 assert_heap_not_locked_and_not_at_safepoint();
891 assert(!is_humongous(word_size), "attempt_allocation() should not "
892 "be called for humongous allocation requests");
893
894 AllocationContext_t context = AllocationContext::current();
895 HeapWord* result = _allocator->attempt_allocation(word_size, context);
896
897 if (result == NULL) {
898 result = attempt_allocation_slow(word_size,
899 context,
900 gc_count_before_ret,
901 gclocker_retry_count_ret);
902 }
903 assert_heap_not_locked();
904 if (result != NULL) {
905 dirty_young_block(result, word_size);
906 }
907 return result;
908 }
909
910 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
911 assert(!is_init_completed(), "Expect to be called at JVM init time");
912 assert(ranges != NULL, "MemRegion array NULL");
913 assert(count != 0, "No MemRegions provided");
914 MemRegion reserved = _hrm.reserved();
915 HeapWord* prev_last_addr = NULL;
916 HeapRegion* prev_last_region = NULL;
917 size_t size_used = 0;
918 size_t uncommitted_regions = 0;
919
920 // For each Memregion, free the G1 regions that constitute it, and
921 // notify mark-sweep that the range is no longer to be considered 'archive.'
922 MutexLockerEx x(Heap_lock);
923 for (size_t i = 0; i < count; i++) {
924 HeapWord* start_address = ranges[i].start();
925 HeapWord* last_address = ranges[i].last();
926
927 assert(reserved.contains(start_address) && reserved.contains(last_address),
928 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
929 p2i(start_address), p2i(last_address));
930 assert(start_address > prev_last_addr,
931 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
932 p2i(start_address), p2i(prev_last_addr));
933 size_used += ranges[i].byte_size();
934 prev_last_addr = last_address;
935
936 HeapRegion* start_region = _hrm.addr_to_region(start_address);
937 HeapRegion* last_region = _hrm.addr_to_region(last_address);
938
939 // Check for ranges that start in the same G1 region in which the previous
940 // range ended, and adjust the start address so we don't try to free
941 // the same region again. If the current range is entirely within that
942 // region, skip it.
943 if (start_region == prev_last_region) {
944 start_address = start_region->end();
945 if (start_address > last_address) {
946 continue;
947 }
948 start_region = _hrm.addr_to_region(start_address);
949 }
950 prev_last_region = last_region;
951
952 // After verifying that each region was marked as an archive region by
953 // alloc_archive_regions, set it free and empty and uncommit it.
954 HeapRegion* curr_region = start_region;
955 while (curr_region != NULL) {
956 guarantee(curr_region->is_archive(),
957 "Expected archive region at index %u", curr_region->hrm_index());
958 uint curr_index = curr_region->hrm_index();
959 _old_set.remove(curr_region);
960 curr_region->set_free();
961 curr_region->set_top(curr_region->bottom());
962 if (curr_region != last_region) {
963 curr_region = _hrm.next_region_in_heap(curr_region);
964 } else {
965 curr_region = NULL;
966 }
967 _hrm.shrink_at(curr_index, 1);
968 uncommitted_regions++;
969 }
970
971 // Notify mark-sweep that this is no longer an archive range.
972 G1MarkSweep::set_range_archive(ranges[i], false);
973 }
974
975 if (uncommitted_regions != 0) {
976 ergo_verbose1(ErgoHeapSizing,
977 "attempt heap shrinking",
978 ergo_format_reason("uncommitted archive regions")
979 ergo_format_byte("total size"),
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 (GC_locker::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 (GC_locker::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 GC_locker::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 warning("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 if (hr->is_free()) {
1199 // We only generate output for non-empty regions.
1200 } else if (hr->is_starts_humongous()) {
1201 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1202 } else if (hr->is_continues_humongous()) {
1203 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1204 } else if (hr->is_archive()) {
1205 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1206 } else if (hr->is_old()) {
1207 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1208 } else {
1209 ShouldNotReachHere();
1210 }
1211 return false;
1212 }
1213
1214 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1215 : _hr_printer(hr_printer) { }
1216 };
1217
1218 void G1CollectedHeap::print_hrm_post_compaction() {
1219 PostCompactionPrinterClosure cl(hr_printer());
1220 heap_region_iterate(&cl);
1221 }
1222
1223 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1224 bool clear_all_soft_refs) {
1225 assert_at_safepoint(true /* should_be_vm_thread */);
1226
1227 if (GC_locker::check_active_before_gc()) {
1228 return false;
1229 }
1230
1231 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1232 gc_timer->register_gc_start();
1233
1234 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1235 GCIdMark gc_id_mark;
1236 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1237
1238 SvcGCMarker sgcm(SvcGCMarker::FULL);
1239 ResourceMark rm;
1240
1241 G1Log::update_level();
1242 print_heap_before_gc();
1243 trace_heap_before_gc(gc_tracer);
1244
1245 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1246
1247 verify_region_sets_optional();
1248
1249 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1250 collector_policy()->should_clear_all_soft_refs();
1251
1252 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1253
1254 {
1255 IsGCActiveMark x;
1256
1257 // Timing
1258 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1259 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1260
1261 {
1262 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1263 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1264 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1265
1266 g1_policy()->record_full_collection_start();
1267
1268 // Note: When we have a more flexible GC logging framework that
1269 // allows us to add optional attributes to a GC log record we
1270 // could consider timing and reporting how long we wait in the
1271 // following two methods.
1272 wait_while_free_regions_coming();
1273 // If we start the compaction before the CM threads finish
1274 // scanning the root regions we might trip them over as we'll
1275 // be moving objects / updating references. So let's wait until
1276 // they are done. By telling them to abort, they should complete
1277 // early.
1278 _cm->root_regions()->abort();
1279 _cm->root_regions()->wait_until_scan_finished();
1280 append_secondary_free_list_if_not_empty_with_lock();
1281
1282 gc_prologue(true);
1283 increment_total_collections(true /* full gc */);
1284 increment_old_marking_cycles_started();
1285
1286 assert(used() == recalculate_used(), "Should be equal");
1287
1288 verify_before_gc();
1289
1290 check_bitmaps("Full GC Start");
1291 pre_full_gc_dump(gc_timer);
1292
1293 #if defined(COMPILER2) || INCLUDE_JVMCI
1294 DerivedPointerTable::clear();
1295 #endif
1296
1297 // Disable discovery and empty the discovered lists
1298 // for the CM ref processor.
1299 ref_processor_cm()->disable_discovery();
1300 ref_processor_cm()->abandon_partial_discovery();
1301 ref_processor_cm()->verify_no_references_recorded();
1302
1303 // Abandon current iterations of concurrent marking and concurrent
1304 // refinement, if any are in progress. We have to do this before
1305 // wait_until_scan_finished() below.
1306 concurrent_mark()->abort();
1307
1308 // Make sure we'll choose a new allocation region afterwards.
1309 _allocator->release_mutator_alloc_region();
1310 _allocator->abandon_gc_alloc_regions();
1311 g1_rem_set()->cleanupHRRS();
1312
1313 // We should call this after we retire any currently active alloc
1314 // regions so that all the ALLOC / RETIRE events are generated
1315 // before the start GC event.
1316 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1317
1318 // We may have added regions to the current incremental collection
1319 // set between the last GC or pause and now. We need to clear the
1320 // incremental collection set and then start rebuilding it afresh
1321 // after this full GC.
1322 abandon_collection_set(g1_policy()->inc_cset_head());
1323 g1_policy()->clear_incremental_cset();
1324 g1_policy()->stop_incremental_cset_building();
1325
1326 tear_down_region_sets(false /* free_list_only */);
1327 collector_state()->set_gcs_are_young(true);
1328
1329 // See the comments in g1CollectedHeap.hpp and
1330 // G1CollectedHeap::ref_processing_init() about
1331 // how reference processing currently works in G1.
1332
1333 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1334 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1335
1336 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1337 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1338
1339 ref_processor_stw()->enable_discovery();
1340 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1341
1342 // Do collection work
1343 {
1344 HandleMark hm; // Discard invalid handles created during gc
1345 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1346 }
1347
1348 assert(num_free_regions() == 0, "we should not have added any free regions");
1349 rebuild_region_sets(false /* free_list_only */);
1350
1351 // Enqueue any discovered reference objects that have
1352 // not been removed from the discovered lists.
1353 ref_processor_stw()->enqueue_discovered_references();
1354
1355 #if defined(COMPILER2) || INCLUDE_JVMCI
1356 DerivedPointerTable::update_pointers();
1357 #endif
1358
1359 MemoryService::track_memory_usage();
1360
1361 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1362 ref_processor_stw()->verify_no_references_recorded();
1363
1364 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1365 ClassLoaderDataGraph::purge();
1366 MetaspaceAux::verify_metrics();
1367
1368 // Note: since we've just done a full GC, concurrent
1369 // marking is no longer active. Therefore we need not
1370 // re-enable reference discovery for the CM ref processor.
1371 // That will be done at the start of the next marking cycle.
1372 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1373 ref_processor_cm()->verify_no_references_recorded();
1374
1375 reset_gc_time_stamp();
1376 // Since everything potentially moved, we will clear all remembered
1377 // sets, and clear all cards. Later we will rebuild remembered
1378 // sets. We will also reset the GC time stamps of the regions.
1379 clear_rsets_post_compaction();
1380 check_gc_time_stamps();
1381
1382 resize_if_necessary_after_full_collection();
1383
1384 if (_hr_printer.is_active()) {
1385 // We should do this after we potentially resize the heap so
1386 // that all the COMMIT / UNCOMMIT events are generated before
1387 // the end GC event.
1388
1389 print_hrm_post_compaction();
1390 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1391 }
1392
1393 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1394 if (hot_card_cache->use_cache()) {
1395 hot_card_cache->reset_card_counts();
1396 hot_card_cache->reset_hot_cache();
1397 }
1398
1399 // Rebuild remembered sets of all regions.
1400 uint n_workers =
1401 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1402 workers()->active_workers(),
1403 Threads::number_of_non_daemon_threads());
1404 workers()->set_active_workers(n_workers);
1405
1406 ParRebuildRSTask rebuild_rs_task(this);
1407 workers()->run_task(&rebuild_rs_task);
1408
1409 // Rebuild the strong code root lists for each region
1410 rebuild_strong_code_roots();
1411
1412 if (true) { // FIXME
1413 MetaspaceGC::compute_new_size();
1414 }
1415
1416 #ifdef TRACESPINNING
1417 ParallelTaskTerminator::print_termination_counts();
1418 #endif
1419
1420 // Discard all rset updates
1421 JavaThread::dirty_card_queue_set().abandon_logs();
1422 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1423
1424 _young_list->reset_sampled_info();
1425 // At this point there should be no regions in the
1426 // entire heap tagged as young.
1427 assert(check_young_list_empty(true /* check_heap */),
1428 "young list should be empty at this point");
1429
1430 // Update the number of full collections that have been completed.
1431 increment_old_marking_cycles_completed(false /* concurrent */);
1432
1433 _hrm.verify_optional();
1434 verify_region_sets_optional();
1435
1436 verify_after_gc();
1437
1438 // Clear the previous marking bitmap, if needed for bitmap verification.
1439 // Note we cannot do this when we clear the next marking bitmap in
1440 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1441 // objects marked during a full GC against the previous bitmap.
1442 // But we need to clear it before calling check_bitmaps below since
1443 // the full GC has compacted objects and updated TAMS but not updated
1444 // the prev bitmap.
1445 if (G1VerifyBitmaps) {
1446 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1447 }
1448 check_bitmaps("Full GC End");
1449
1450 // Start a new incremental collection set for the next pause
1451 assert(g1_policy()->collection_set() == NULL, "must be");
1452 g1_policy()->start_incremental_cset_building();
1453
1454 clear_cset_fast_test();
1455
1456 _allocator->init_mutator_alloc_region();
1457
1458 g1_policy()->record_full_collection_end();
1459
1460 if (G1Log::fine()) {
1461 g1_policy()->print_heap_transition();
1462 }
1463
1464 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1465 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1466 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1467 // before any GC notifications are raised.
1468 g1mm()->update_sizes();
1469
1470 gc_epilogue(true);
1471 }
1472
1473 if (G1Log::finer()) {
1474 g1_policy()->print_detailed_heap_transition(true /* full */);
1475 }
1476
1477 print_heap_after_gc();
1478 trace_heap_after_gc(gc_tracer);
1479
1480 post_full_gc_dump(gc_timer);
1481
1482 gc_timer->register_gc_end();
1483 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1484 }
1485
1486 return true;
1487 }
1488
1489 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1490 // Currently, there is no facility in the do_full_collection(bool) API to notify
1491 // the caller that the collection did not succeed (e.g., because it was locked
1492 // out by the GC locker). So, right now, we'll ignore the return value.
1493 bool dummy = do_full_collection(true, /* explicit_gc */
1494 clear_all_soft_refs);
1495 }
1496
1497 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1498 // Include bytes that will be pre-allocated to support collections, as "used".
1499 const size_t used_after_gc = used();
1500 const size_t capacity_after_gc = capacity();
1501 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1502
1503 // This is enforced in arguments.cpp.
1504 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1505 "otherwise the code below doesn't make sense");
1506
1507 // We don't have floating point command-line arguments
1508 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1509 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1510 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1511 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1512
1513 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1514 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1515
1516 // We have to be careful here as these two calculations can overflow
1517 // 32-bit size_t's.
1518 double used_after_gc_d = (double) used_after_gc;
1519 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1520 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1521
1522 // Let's make sure that they are both under the max heap size, which
1523 // by default will make them fit into a size_t.
1524 double desired_capacity_upper_bound = (double) max_heap_size;
1525 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1526 desired_capacity_upper_bound);
1527 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1528 desired_capacity_upper_bound);
1529
1530 // We can now safely turn them into size_t's.
1531 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1532 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1533
1534 // This assert only makes sense here, before we adjust them
1535 // with respect to the min and max heap size.
1536 assert(minimum_desired_capacity <= maximum_desired_capacity,
1537 "minimum_desired_capacity = " SIZE_FORMAT ", "
1538 "maximum_desired_capacity = " SIZE_FORMAT,
1539 minimum_desired_capacity, maximum_desired_capacity);
1540
1541 // Should not be greater than the heap max size. No need to adjust
1542 // it with respect to the heap min size as it's a lower bound (i.e.,
1543 // we'll try to make the capacity larger than it, not smaller).
1544 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1545 // Should not be less than the heap min size. No need to adjust it
1546 // with respect to the heap max size as it's an upper bound (i.e.,
1547 // we'll try to make the capacity smaller than it, not greater).
1548 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1549
1550 if (capacity_after_gc < minimum_desired_capacity) {
1551 // Don't expand unless it's significant
1552 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1553 ergo_verbose4(ErgoHeapSizing,
1554 "attempt heap expansion",
1555 ergo_format_reason("capacity lower than "
1556 "min desired capacity after Full GC")
1557 ergo_format_byte("capacity")
1558 ergo_format_byte("occupancy")
1559 ergo_format_byte_perc("min desired capacity"),
1560 capacity_after_gc, used_after_gc,
1561 minimum_desired_capacity, (double) MinHeapFreeRatio);
1562 expand(expand_bytes);
1563
1564 // No expansion, now see if we want to shrink
1565 } else if (capacity_after_gc > maximum_desired_capacity) {
1566 // Capacity too large, compute shrinking size
1567 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1568 ergo_verbose4(ErgoHeapSizing,
1569 "attempt heap shrinking",
1570 ergo_format_reason("capacity higher than "
1571 "max desired capacity after Full GC")
1572 ergo_format_byte("capacity")
1573 ergo_format_byte("occupancy")
1574 ergo_format_byte_perc("max desired capacity"),
1575 capacity_after_gc, used_after_gc,
1576 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1577 shrink(shrink_bytes);
1578 }
1579 }
1580
1581 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1582 AllocationContext_t context,
1583 bool do_gc,
1584 bool clear_all_soft_refs,
1585 bool expect_null_mutator_alloc_region,
1586 bool* gc_succeeded) {
1587 *gc_succeeded = true;
1588 // Let's attempt the allocation first.
1589 HeapWord* result =
1590 attempt_allocation_at_safepoint(word_size,
1591 context,
1592 expect_null_mutator_alloc_region);
1593 if (result != NULL) {
1594 assert(*gc_succeeded, "sanity");
1595 return result;
1596 }
1597
1598 // In a G1 heap, we're supposed to keep allocation from failing by
1599 // incremental pauses. Therefore, at least for now, we'll favor
1600 // expansion over collection. (This might change in the future if we can
1601 // do something smarter than full collection to satisfy a failed alloc.)
1602 result = expand_and_allocate(word_size, context);
1603 if (result != NULL) {
1604 assert(*gc_succeeded, "sanity");
1605 return result;
1606 }
1607
1608 if (do_gc) {
1609 // Expansion didn't work, we'll try to do a Full GC.
1610 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1611 clear_all_soft_refs);
1612 }
1613
1614 return NULL;
1615 }
1616
1617 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1618 AllocationContext_t context,
1619 bool* succeeded) {
1620 assert_at_safepoint(true /* should_be_vm_thread */);
1621
1622 // Attempts to allocate followed by Full GC.
1623 HeapWord* result =
1624 satisfy_failed_allocation_helper(word_size,
1625 context,
1626 true, /* do_gc */
1627 false, /* clear_all_soft_refs */
1628 false, /* expect_null_mutator_alloc_region */
1629 succeeded);
1630
1631 if (result != NULL || !*succeeded) {
1632 return result;
1633 }
1634
1635 // Attempts to allocate followed by Full GC that will collect all soft references.
1636 result = satisfy_failed_allocation_helper(word_size,
1637 context,
1638 true, /* do_gc */
1639 true, /* clear_all_soft_refs */
1640 true, /* expect_null_mutator_alloc_region */
1641 succeeded);
1642
1643 if (result != NULL || !*succeeded) {
1644 return result;
1645 }
1646
1647 // Attempts to allocate, no GC
1648 result = satisfy_failed_allocation_helper(word_size,
1649 context,
1650 false, /* do_gc */
1651 false, /* clear_all_soft_refs */
1652 true, /* expect_null_mutator_alloc_region */
1653 succeeded);
1654
1655 if (result != NULL) {
1656 assert(*succeeded, "sanity");
1657 return result;
1658 }
1659
1660 assert(!collector_policy()->should_clear_all_soft_refs(),
1661 "Flag should have been handled and cleared prior to this point");
1662
1663 // What else? We might try synchronous finalization later. If the total
1664 // space available is large enough for the allocation, then a more
1665 // complete compaction phase than we've tried so far might be
1666 // appropriate.
1667 assert(*succeeded, "sanity");
1668 return NULL;
1669 }
1670
1671 // Attempting to expand the heap sufficiently
1672 // to support an allocation of the given "word_size". If
1673 // successful, perform the allocation and return the address of the
1674 // allocated block, or else "NULL".
1675
1676 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1677 assert_at_safepoint(true /* should_be_vm_thread */);
1678
1679 verify_region_sets_optional();
1680
1681 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1682 ergo_verbose1(ErgoHeapSizing,
1683 "attempt heap expansion",
1684 ergo_format_reason("allocation request failed")
1685 ergo_format_byte("allocation request"),
1686 word_size * HeapWordSize);
1687 if (expand(expand_bytes)) {
1688 _hrm.verify_optional();
1689 verify_region_sets_optional();
1690 return attempt_allocation_at_safepoint(word_size,
1691 context,
1692 false /* expect_null_mutator_alloc_region */);
1693 }
1694 return NULL;
1695 }
1696
1697 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1698 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1699 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1700 HeapRegion::GrainBytes);
1701 ergo_verbose2(ErgoHeapSizing,
1702 "expand the heap",
1703 ergo_format_byte("requested expansion amount")
1704 ergo_format_byte("attempted expansion amount"),
1705 expand_bytes, aligned_expand_bytes);
1706
1707 if (is_maximal_no_gc()) {
1708 ergo_verbose0(ErgoHeapSizing,
1709 "did not expand the heap",
1710 ergo_format_reason("heap already fully expanded"));
1711 return false;
1712 }
1713
1714 double expand_heap_start_time_sec = os::elapsedTime();
1715 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1716 assert(regions_to_expand > 0, "Must expand by at least one region");
1717
1718 uint expanded_by = _hrm.expand_by(regions_to_expand);
1719 if (expand_time_ms != NULL) {
1720 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1721 }
1722
1723 if (expanded_by > 0) {
1724 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1725 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1726 g1_policy()->record_new_heap_size(num_regions());
1727 } else {
1728 ergo_verbose0(ErgoHeapSizing,
1729 "did not expand the heap",
1730 ergo_format_reason("heap expansion operation failed"));
1731 // The expansion of the virtual storage space was unsuccessful.
1732 // Let's see if it was because we ran out of swap.
1733 if (G1ExitOnExpansionFailure &&
1734 _hrm.available() >= regions_to_expand) {
1735 // We had head room...
1736 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1737 }
1738 }
1739 return regions_to_expand > 0;
1740 }
1741
1742 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1743 size_t aligned_shrink_bytes =
1744 ReservedSpace::page_align_size_down(shrink_bytes);
1745 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1746 HeapRegion::GrainBytes);
1747 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1748
1749 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1750 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1751
1752 ergo_verbose3(ErgoHeapSizing,
1753 "shrink the heap",
1754 ergo_format_byte("requested shrinking amount")
1755 ergo_format_byte("aligned shrinking amount")
1756 ergo_format_byte("attempted shrinking amount"),
1757 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1758 if (num_regions_removed > 0) {
1759 g1_policy()->record_new_heap_size(num_regions());
1760 } else {
1761 ergo_verbose0(ErgoHeapSizing,
1762 "did not shrink the heap",
1763 ergo_format_reason("heap shrinking operation failed"));
1764 }
1765 }
1766
1767 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1768 verify_region_sets_optional();
1769
1770 // We should only reach here at the end of a Full GC which means we
1771 // should not not be holding to any GC alloc regions. The method
1772 // below will make sure of that and do any remaining clean up.
1773 _allocator->abandon_gc_alloc_regions();
1774
1775 // Instead of tearing down / rebuilding the free lists here, we
1776 // could instead use the remove_all_pending() method on free_list to
1777 // remove only the ones that we need to remove.
1778 tear_down_region_sets(true /* free_list_only */);
1779 shrink_helper(shrink_bytes);
1780 rebuild_region_sets(true /* free_list_only */);
1781
1782 _hrm.verify_optional();
1783 verify_region_sets_optional();
1784 }
1785
1786 // Public methods.
1787
1788 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1789 CollectedHeap(),
1790 _g1_policy(policy_),
1791 _dirty_card_queue_set(false),
1792 _is_alive_closure_cm(this),
1793 _is_alive_closure_stw(this),
1794 _ref_processor_cm(NULL),
1795 _ref_processor_stw(NULL),
1796 _bot_shared(NULL),
1797 _cg1r(NULL),
1798 _g1mm(NULL),
1799 _refine_cte_cl(NULL),
1800 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1801 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1802 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1803 _humongous_reclaim_candidates(),
1804 _has_humongous_reclaim_candidates(false),
1805 _archive_allocator(NULL),
1806 _free_regions_coming(false),
1807 _young_list(new YoungList(this)),
1808 _gc_time_stamp(0),
1809 _summary_bytes_used(0),
1810 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1811 _old_evac_stats(OldPLABSize, PLABWeight),
1812 _expand_heap_after_alloc_failure(true),
1813 _old_marking_cycles_started(0),
1814 _old_marking_cycles_completed(0),
1815 _heap_summary_sent(false),
1816 _in_cset_fast_test(),
1817 _dirty_cards_region_list(NULL),
1818 _worker_cset_start_region(NULL),
1819 _worker_cset_start_region_time_stamp(NULL),
1820 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1821 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1822 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1823 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1824
1825 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1826 /* are_GC_task_threads */true,
1827 /* are_ConcurrentGC_threads */false);
1828 _workers->initialize_workers();
1829
1830 _allocator = G1Allocator::create_allocator(this);
1831 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1832
1833 // Override the default _filler_array_max_size so that no humongous filler
1834 // objects are created.
1835 _filler_array_max_size = _humongous_object_threshold_in_words;
1836
1837 uint n_queues = ParallelGCThreads;
1838 _task_queues = new RefToScanQueueSet(n_queues);
1839
1840 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1841 assert(n_rem_sets > 0, "Invariant.");
1842
1843 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1844 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1845 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1846
1847 for (uint i = 0; i < n_queues; i++) {
1848 RefToScanQueue* q = new RefToScanQueue();
1849 q->initialize();
1850 _task_queues->register_queue(i, q);
1851 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1852 }
1853 clear_cset_start_regions();
1854
1855 // Initialize the G1EvacuationFailureALot counters and flags.
1856 NOT_PRODUCT(reset_evacuation_should_fail();)
1857
1858 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1859 }
1860
1861 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1862 size_t size,
1863 size_t translation_factor) {
1864 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1865 // Allocate a new reserved space, preferring to use large pages.
1866 ReservedSpace rs(size, preferred_page_size);
1867 G1RegionToSpaceMapper* result =
1868 G1RegionToSpaceMapper::create_mapper(rs,
1869 size,
1870 rs.alignment(),
1871 HeapRegion::GrainBytes,
1872 translation_factor,
1873 mtGC);
1874 if (TracePageSizes) {
1875 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1876 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1877 }
1878 return result;
1879 }
1880
1881 jint G1CollectedHeap::initialize() {
1882 CollectedHeap::pre_initialize();
1883 os::enable_vtime();
1884
1885 G1Log::init();
1886
1887 // Necessary to satisfy locking discipline assertions.
1888
1889 MutexLocker x(Heap_lock);
1890
1891 // We have to initialize the printer before committing the heap, as
1892 // it will be used then.
1893 _hr_printer.set_active(G1PrintHeapRegions);
1894
1895 // While there are no constraints in the GC code that HeapWordSize
1896 // be any particular value, there are multiple other areas in the
1897 // system which believe this to be true (e.g. oop->object_size in some
1898 // cases incorrectly returns the size in wordSize units rather than
1899 // HeapWordSize).
1900 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1901
1902 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1903 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1904 size_t heap_alignment = collector_policy()->heap_alignment();
1905
1906 // Ensure that the sizes are properly aligned.
1907 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1908 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1909 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1910
1911 _refine_cte_cl = new RefineCardTableEntryClosure();
1912
1913 jint ecode = JNI_OK;
1914 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1915 if (_cg1r == NULL) {
1916 return ecode;
1917 }
1918
1919 // Reserve the maximum.
1920
1921 // When compressed oops are enabled, the preferred heap base
1922 // is calculated by subtracting the requested size from the
1923 // 32Gb boundary and using the result as the base address for
1924 // heap reservation. If the requested size is not aligned to
1925 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1926 // into the ReservedHeapSpace constructor) then the actual
1927 // base of the reserved heap may end up differing from the
1928 // address that was requested (i.e. the preferred heap base).
1929 // If this happens then we could end up using a non-optimal
1930 // compressed oops mode.
1931
1932 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1933 heap_alignment);
1934
1935 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1936
1937 // Create the barrier set for the entire reserved region.
1938 G1SATBCardTableLoggingModRefBS* bs
1939 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1940 bs->initialize();
1941 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1942 set_barrier_set(bs);
1943
1944 // Also create a G1 rem set.
1945 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1946
1947 // Carve out the G1 part of the heap.
1948
1949 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1950 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1951 G1RegionToSpaceMapper* heap_storage =
1952 G1RegionToSpaceMapper::create_mapper(g1_rs,
1953 g1_rs.size(),
1954 page_size,
1955 HeapRegion::GrainBytes,
1956 1,
1957 mtJavaHeap);
1958 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1959 max_byte_size, page_size,
1960 heap_rs.base(),
1961 heap_rs.size());
1962 heap_storage->set_mapping_changed_listener(&_listener);
1963
1964 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1965 G1RegionToSpaceMapper* bot_storage =
1966 create_aux_memory_mapper("Block offset table",
1967 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1968 G1BlockOffsetSharedArray::heap_map_factor());
1969
1970 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1971 G1RegionToSpaceMapper* cardtable_storage =
1972 create_aux_memory_mapper("Card table",
1973 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1974 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1975
1976 G1RegionToSpaceMapper* card_counts_storage =
1977 create_aux_memory_mapper("Card counts table",
1978 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1979 G1CardCounts::heap_map_factor());
1980
1981 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1982 G1RegionToSpaceMapper* prev_bitmap_storage =
1983 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1984 G1RegionToSpaceMapper* next_bitmap_storage =
1985 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1986
1987 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1988 g1_barrier_set()->initialize(cardtable_storage);
1989 // Do later initialization work for concurrent refinement.
1990 _cg1r->init(card_counts_storage);
1991
1992 // 6843694 - ensure that the maximum region index can fit
1993 // in the remembered set structures.
1994 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1995 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1996
1997 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1998 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1999 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2000 "too many cards per region");
2001
2002 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2003
2004 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2005
2006 {
2007 HeapWord* start = _hrm.reserved().start();
2008 HeapWord* end = _hrm.reserved().end();
2009 size_t granularity = HeapRegion::GrainBytes;
2010
2011 _in_cset_fast_test.initialize(start, end, granularity);
2012 _humongous_reclaim_candidates.initialize(start, end, granularity);
2013 }
2014
2015 // Create the ConcurrentMark data structure and thread.
2016 // (Must do this late, so that "max_regions" is defined.)
2017 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2018 if (_cm == NULL || !_cm->completed_initialization()) {
2019 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2020 return JNI_ENOMEM;
2021 }
2022 _cmThread = _cm->cmThread();
2023
2024 // Initialize the from_card cache structure of HeapRegionRemSet.
2025 HeapRegionRemSet::init_heap(max_regions());
2026
2027 // Now expand into the initial heap size.
2028 if (!expand(init_byte_size)) {
2029 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2030 return JNI_ENOMEM;
2031 }
2032
2033 // Perform any initialization actions delegated to the policy.
2034 g1_policy()->init();
2035
2036 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2037 SATB_Q_FL_lock,
2038 G1SATBProcessCompletedThreshold,
2039 Shared_SATB_Q_lock);
2040
2041 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2042 DirtyCardQ_CBL_mon,
2043 DirtyCardQ_FL_lock,
2044 concurrent_g1_refine()->yellow_zone(),
2045 concurrent_g1_refine()->red_zone(),
2046 Shared_DirtyCardQ_lock);
2047
2048 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2049 DirtyCardQ_CBL_mon,
2050 DirtyCardQ_FL_lock,
2051 -1, // never trigger processing
2052 -1, // no limit on length
2053 Shared_DirtyCardQ_lock,
2054 &JavaThread::dirty_card_queue_set());
2055
2056 // Here we allocate the dummy HeapRegion that is required by the
2057 // G1AllocRegion class.
2058 HeapRegion* dummy_region = _hrm.get_dummy_region();
2059
2060 // We'll re-use the same region whether the alloc region will
2061 // require BOT updates or not and, if it doesn't, then a non-young
2062 // region will complain that it cannot support allocations without
2063 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2064 dummy_region->set_eden();
2065 // Make sure it's full.
2066 dummy_region->set_top(dummy_region->end());
2067 G1AllocRegion::setup(this, dummy_region);
2068
2069 _allocator->init_mutator_alloc_region();
2070
2071 // Do create of the monitoring and management support so that
2072 // values in the heap have been properly initialized.
2073 _g1mm = new G1MonitoringSupport(this);
2074
2075 G1StringDedup::initialize();
2076
2077 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2078 for (uint i = 0; i < ParallelGCThreads; i++) {
2079 new (&_preserved_objs[i]) OopAndMarkOopStack();
2080 }
2081
2082 return JNI_OK;
2083 }
2084
2085 void G1CollectedHeap::stop() {
2086 // Stop all concurrent threads. We do this to make sure these threads
2087 // do not continue to execute and access resources (e.g. gclog_or_tty)
2088 // that are destroyed during shutdown.
2089 _cg1r->stop();
2090 _cmThread->stop();
2091 if (G1StringDedup::is_enabled()) {
2092 G1StringDedup::stop();
2093 }
2094 }
2095
2096 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2097 return HeapRegion::max_region_size();
2098 }
2099
2100 void G1CollectedHeap::post_initialize() {
2101 CollectedHeap::post_initialize();
2102 ref_processing_init();
2103 }
2104
2105 void G1CollectedHeap::ref_processing_init() {
2106 // Reference processing in G1 currently works as follows:
2107 //
2108 // * There are two reference processor instances. One is
2109 // used to record and process discovered references
2110 // during concurrent marking; the other is used to
2111 // record and process references during STW pauses
2112 // (both full and incremental).
2113 // * Both ref processors need to 'span' the entire heap as
2114 // the regions in the collection set may be dotted around.
2115 //
2116 // * For the concurrent marking ref processor:
2117 // * Reference discovery is enabled at initial marking.
2118 // * Reference discovery is disabled and the discovered
2119 // references processed etc during remarking.
2120 // * Reference discovery is MT (see below).
2121 // * Reference discovery requires a barrier (see below).
2122 // * Reference processing may or may not be MT
2123 // (depending on the value of ParallelRefProcEnabled
2124 // and ParallelGCThreads).
2125 // * A full GC disables reference discovery by the CM
2126 // ref processor and abandons any entries on it's
2127 // discovered lists.
2128 //
2129 // * For the STW processor:
2130 // * Non MT discovery is enabled at the start of a full GC.
2131 // * Processing and enqueueing during a full GC is non-MT.
2132 // * During a full GC, references are processed after marking.
2133 //
2134 // * Discovery (may or may not be MT) is enabled at the start
2135 // of an incremental evacuation pause.
2136 // * References are processed near the end of a STW evacuation pause.
2137 // * For both types of GC:
2138 // * Discovery is atomic - i.e. not concurrent.
2139 // * Reference discovery will not need a barrier.
2140
2141 MemRegion mr = reserved_region();
2142
2143 // Concurrent Mark ref processor
2144 _ref_processor_cm =
2145 new ReferenceProcessor(mr, // span
2146 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2147 // mt processing
2148 ParallelGCThreads,
2149 // degree of mt processing
2150 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2151 // mt discovery
2152 MAX2(ParallelGCThreads, ConcGCThreads),
2153 // degree of mt discovery
2154 false,
2155 // Reference discovery is not atomic
2156 &_is_alive_closure_cm);
2157 // is alive closure
2158 // (for efficiency/performance)
2159
2160 // STW ref processor
2161 _ref_processor_stw =
2162 new ReferenceProcessor(mr, // span
2163 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2164 // mt processing
2165 ParallelGCThreads,
2166 // degree of mt processing
2167 (ParallelGCThreads > 1),
2168 // mt discovery
2169 ParallelGCThreads,
2170 // degree of mt discovery
2171 true,
2172 // Reference discovery is atomic
2173 &_is_alive_closure_stw);
2174 // is alive closure
2175 // (for efficiency/performance)
2176 }
2177
2178 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2179 return g1_policy();
2180 }
2181
2182 size_t G1CollectedHeap::capacity() const {
2183 return _hrm.length() * HeapRegion::GrainBytes;
2184 }
2185
2186 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2187 hr->reset_gc_time_stamp();
2188 }
2189
2190 #ifndef PRODUCT
2191
2192 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2193 private:
2194 unsigned _gc_time_stamp;
2195 bool _failures;
2196
2197 public:
2198 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2199 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2200
2201 virtual bool doHeapRegion(HeapRegion* hr) {
2202 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2203 if (_gc_time_stamp != region_gc_time_stamp) {
2204 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2205 "expected %d", HR_FORMAT_PARAMS(hr),
2206 region_gc_time_stamp, _gc_time_stamp);
2207 _failures = true;
2208 }
2209 return false;
2210 }
2211
2212 bool failures() { return _failures; }
2213 };
2214
2215 void G1CollectedHeap::check_gc_time_stamps() {
2216 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2217 heap_region_iterate(&cl);
2218 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2219 }
2220 #endif // PRODUCT
2221
2222 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2223 _cg1r->hot_card_cache()->drain(cl, worker_i);
2224 }
2225
2226 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2227 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2228 size_t n_completed_buffers = 0;
2229 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2230 n_completed_buffers++;
2231 }
2232 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2233 dcqs.clear_n_completed_buffers();
2234 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2235 }
2236
2237 // Computes the sum of the storage used by the various regions.
2238 size_t G1CollectedHeap::used() const {
2239 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2240 if (_archive_allocator != NULL) {
2241 result += _archive_allocator->used();
2242 }
2243 return result;
2244 }
2245
2246 size_t G1CollectedHeap::used_unlocked() const {
2247 return _summary_bytes_used;
2248 }
2249
2250 class SumUsedClosure: public HeapRegionClosure {
2251 size_t _used;
2252 public:
2253 SumUsedClosure() : _used(0) {}
2254 bool doHeapRegion(HeapRegion* r) {
2255 _used += r->used();
2256 return false;
2257 }
2258 size_t result() { return _used; }
2259 };
2260
2261 size_t G1CollectedHeap::recalculate_used() const {
2262 double recalculate_used_start = os::elapsedTime();
2263
2264 SumUsedClosure blk;
2265 heap_region_iterate(&blk);
2266
2267 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2268 return blk.result();
2269 }
2270
2271 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2272 switch (cause) {
2273 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2274 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2275 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2276 case GCCause::_g1_humongous_allocation: return true;
2277 case GCCause::_update_allocation_context_stats_inc: return true;
2278 case GCCause::_wb_conc_mark: return true;
2279 default: return false;
2280 }
2281 }
2282
2283 #ifndef PRODUCT
2284 void G1CollectedHeap::allocate_dummy_regions() {
2285 // Let's fill up most of the region
2286 size_t word_size = HeapRegion::GrainWords - 1024;
2287 // And as a result the region we'll allocate will be humongous.
2288 guarantee(is_humongous(word_size), "sanity");
2289
2290 // _filler_array_max_size is set to humongous object threshold
2291 // but temporarily change it to use CollectedHeap::fill_with_object().
2292 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2293
2294 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2295 // Let's use the existing mechanism for the allocation
2296 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2297 AllocationContext::system());
2298 if (dummy_obj != NULL) {
2299 MemRegion mr(dummy_obj, word_size);
2300 CollectedHeap::fill_with_object(mr);
2301 } else {
2302 // If we can't allocate once, we probably cannot allocate
2303 // again. Let's get out of the loop.
2304 break;
2305 }
2306 }
2307 }
2308 #endif // !PRODUCT
2309
2310 void G1CollectedHeap::increment_old_marking_cycles_started() {
2311 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2312 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2313 "Wrong marking cycle count (started: %d, completed: %d)",
2314 _old_marking_cycles_started, _old_marking_cycles_completed);
2315
2316 _old_marking_cycles_started++;
2317 }
2318
2319 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2320 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2321
2322 // We assume that if concurrent == true, then the caller is a
2323 // concurrent thread that was joined the Suspendible Thread
2324 // Set. If there's ever a cheap way to check this, we should add an
2325 // assert here.
2326
2327 // Given that this method is called at the end of a Full GC or of a
2328 // concurrent cycle, and those can be nested (i.e., a Full GC can
2329 // interrupt a concurrent cycle), the number of full collections
2330 // completed should be either one (in the case where there was no
2331 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2332 // behind the number of full collections started.
2333
2334 // This is the case for the inner caller, i.e. a Full GC.
2335 assert(concurrent ||
2336 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2337 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2338 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2339 "is inconsistent with _old_marking_cycles_completed = %u",
2340 _old_marking_cycles_started, _old_marking_cycles_completed);
2341
2342 // This is the case for the outer caller, i.e. the concurrent cycle.
2343 assert(!concurrent ||
2344 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2345 "for outer caller (concurrent cycle): "
2346 "_old_marking_cycles_started = %u "
2347 "is inconsistent with _old_marking_cycles_completed = %u",
2348 _old_marking_cycles_started, _old_marking_cycles_completed);
2349
2350 _old_marking_cycles_completed += 1;
2351
2352 // We need to clear the "in_progress" flag in the CM thread before
2353 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2354 // is set) so that if a waiter requests another System.gc() it doesn't
2355 // incorrectly see that a marking cycle is still in progress.
2356 if (concurrent) {
2357 _cmThread->set_idle();
2358 }
2359
2360 // This notify_all() will ensure that a thread that called
2361 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2362 // and it's waiting for a full GC to finish will be woken up. It is
2363 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2364 FullGCCount_lock->notify_all();
2365 }
2366
2367 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2368 GCIdMarkAndRestore conc_gc_id_mark;
2369 collector_state()->set_concurrent_cycle_started(true);
2370 _gc_timer_cm->register_gc_start(start_time);
2371
2372 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2373 trace_heap_before_gc(_gc_tracer_cm);
2374 _cmThread->set_gc_id(GCId::current());
2375 }
2376
2377 void G1CollectedHeap::register_concurrent_cycle_end() {
2378 if (collector_state()->concurrent_cycle_started()) {
2379 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2380 if (_cm->has_aborted()) {
2381 _gc_tracer_cm->report_concurrent_mode_failure();
2382 }
2383
2384 _gc_timer_cm->register_gc_end();
2385 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2386
2387 // Clear state variables to prepare for the next concurrent cycle.
2388 collector_state()->set_concurrent_cycle_started(false);
2389 _heap_summary_sent = false;
2390 }
2391 }
2392
2393 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2394 if (collector_state()->concurrent_cycle_started()) {
2395 // This function can be called when:
2396 // the cleanup pause is run
2397 // the concurrent cycle is aborted before the cleanup pause.
2398 // the concurrent cycle is aborted after the cleanup pause,
2399 // but before the concurrent cycle end has been registered.
2400 // Make sure that we only send the heap information once.
2401 if (!_heap_summary_sent) {
2402 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2403 trace_heap_after_gc(_gc_tracer_cm);
2404 _heap_summary_sent = true;
2405 }
2406 }
2407 }
2408
2409 void G1CollectedHeap::collect(GCCause::Cause cause) {
2410 assert_heap_not_locked();
2411
2412 uint gc_count_before;
2413 uint old_marking_count_before;
2414 uint full_gc_count_before;
2415 bool retry_gc;
2416
2417 do {
2418 retry_gc = false;
2419
2420 {
2421 MutexLocker ml(Heap_lock);
2422
2423 // Read the GC count while holding the Heap_lock
2424 gc_count_before = total_collections();
2425 full_gc_count_before = total_full_collections();
2426 old_marking_count_before = _old_marking_cycles_started;
2427 }
2428
2429 if (should_do_concurrent_full_gc(cause)) {
2430 // Schedule an initial-mark evacuation pause that will start a
2431 // concurrent cycle. We're setting word_size to 0 which means that
2432 // we are not requesting a post-GC allocation.
2433 VM_G1IncCollectionPause op(gc_count_before,
2434 0, /* word_size */
2435 true, /* should_initiate_conc_mark */
2436 g1_policy()->max_pause_time_ms(),
2437 cause);
2438 op.set_allocation_context(AllocationContext::current());
2439
2440 VMThread::execute(&op);
2441 if (!op.pause_succeeded()) {
2442 if (old_marking_count_before == _old_marking_cycles_started) {
2443 retry_gc = op.should_retry_gc();
2444 } else {
2445 // A Full GC happened while we were trying to schedule the
2446 // initial-mark GC. No point in starting a new cycle given
2447 // that the whole heap was collected anyway.
2448 }
2449
2450 if (retry_gc) {
2451 if (GC_locker::is_active_and_needs_gc()) {
2452 GC_locker::stall_until_clear();
2453 }
2454 }
2455 }
2456 } else {
2457 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2458 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2459
2460 // Schedule a standard evacuation pause. We're setting word_size
2461 // to 0 which means that we are not requesting a post-GC allocation.
2462 VM_G1IncCollectionPause op(gc_count_before,
2463 0, /* word_size */
2464 false, /* should_initiate_conc_mark */
2465 g1_policy()->max_pause_time_ms(),
2466 cause);
2467 VMThread::execute(&op);
2468 } else {
2469 // Schedule a Full GC.
2470 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2471 VMThread::execute(&op);
2472 }
2473 }
2474 } while (retry_gc);
2475 }
2476
2477 bool G1CollectedHeap::is_in(const void* p) const {
2478 if (_hrm.reserved().contains(p)) {
2479 // Given that we know that p is in the reserved space,
2480 // heap_region_containing() should successfully
2481 // return the containing region.
2482 HeapRegion* hr = heap_region_containing(p);
2483 return hr->is_in(p);
2484 } else {
2485 return false;
2486 }
2487 }
2488
2489 #ifdef ASSERT
2490 bool G1CollectedHeap::is_in_exact(const void* p) const {
2491 bool contains = reserved_region().contains(p);
2492 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2493 if (contains && available) {
2494 return true;
2495 } else {
2496 return false;
2497 }
2498 }
2499 #endif
2500
2501 bool G1CollectedHeap::obj_in_cs(oop obj) {
2502 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2503 return r != NULL && r->in_collection_set();
2504 }
2505
2506 // Iteration functions.
2507
2508 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2509
2510 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2511 ExtendedOopClosure* _cl;
2512 public:
2513 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2514 bool doHeapRegion(HeapRegion* r) {
2515 if (!r->is_continues_humongous()) {
2516 r->oop_iterate(_cl);
2517 }
2518 return false;
2519 }
2520 };
2521
2522 // Iterates an ObjectClosure over all objects within a HeapRegion.
2523
2524 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2525 ObjectClosure* _cl;
2526 public:
2527 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2528 bool doHeapRegion(HeapRegion* r) {
2529 if (!r->is_continues_humongous()) {
2530 r->object_iterate(_cl);
2531 }
2532 return false;
2533 }
2534 };
2535
2536 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2537 IterateObjectClosureRegionClosure blk(cl);
2538 heap_region_iterate(&blk);
2539 }
2540
2541 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2542 _hrm.iterate(cl);
2543 }
2544
2545 void
2546 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2547 uint worker_id,
2548 HeapRegionClaimer *hrclaimer,
2549 bool concurrent) const {
2550 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2551 }
2552
2553 // Clear the cached CSet starting regions and (more importantly)
2554 // the time stamps. Called when we reset the GC time stamp.
2555 void G1CollectedHeap::clear_cset_start_regions() {
2556 assert(_worker_cset_start_region != NULL, "sanity");
2557 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2558
2559 for (uint i = 0; i < ParallelGCThreads; i++) {
2560 _worker_cset_start_region[i] = NULL;
2561 _worker_cset_start_region_time_stamp[i] = 0;
2562 }
2563 }
2564
2565 // Given the id of a worker, obtain or calculate a suitable
2566 // starting region for iterating over the current collection set.
2567 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2568 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2569
2570 HeapRegion* result = NULL;
2571 unsigned gc_time_stamp = get_gc_time_stamp();
2572
2573 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2574 // Cached starting region for current worker was set
2575 // during the current pause - so it's valid.
2576 // Note: the cached starting heap region may be NULL
2577 // (when the collection set is empty).
2578 result = _worker_cset_start_region[worker_i];
2579 assert(result == NULL || result->in_collection_set(), "sanity");
2580 return result;
2581 }
2582
2583 // The cached entry was not valid so let's calculate
2584 // a suitable starting heap region for this worker.
2585
2586 // We want the parallel threads to start their collection
2587 // set iteration at different collection set regions to
2588 // avoid contention.
2589 // If we have:
2590 // n collection set regions
2591 // p threads
2592 // Then thread t will start at region floor ((t * n) / p)
2593
2594 result = g1_policy()->collection_set();
2595 uint cs_size = g1_policy()->cset_region_length();
2596 uint active_workers = workers()->active_workers();
2597
2598 uint end_ind = (cs_size * worker_i) / active_workers;
2599 uint start_ind = 0;
2600
2601 if (worker_i > 0 &&
2602 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2603 // Previous workers starting region is valid
2604 // so let's iterate from there
2605 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2606 result = _worker_cset_start_region[worker_i - 1];
2607 }
2608
2609 for (uint i = start_ind; i < end_ind; i++) {
2610 result = result->next_in_collection_set();
2611 }
2612
2613 // Note: the calculated starting heap region may be NULL
2614 // (when the collection set is empty).
2615 assert(result == NULL || result->in_collection_set(), "sanity");
2616 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2617 "should be updated only once per pause");
2618 _worker_cset_start_region[worker_i] = result;
2619 OrderAccess::storestore();
2620 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2621 return result;
2622 }
2623
2624 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2625 HeapRegion* r = g1_policy()->collection_set();
2626 while (r != NULL) {
2627 HeapRegion* next = r->next_in_collection_set();
2628 if (cl->doHeapRegion(r)) {
2629 cl->incomplete();
2630 return;
2631 }
2632 r = next;
2633 }
2634 }
2635
2636 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2637 HeapRegionClosure *cl) {
2638 if (r == NULL) {
2639 // The CSet is empty so there's nothing to do.
2640 return;
2641 }
2642
2643 assert(r->in_collection_set(),
2644 "Start region must be a member of the collection set.");
2645 HeapRegion* cur = r;
2646 while (cur != NULL) {
2647 HeapRegion* next = cur->next_in_collection_set();
2648 if (cl->doHeapRegion(cur) && false) {
2649 cl->incomplete();
2650 return;
2651 }
2652 cur = next;
2653 }
2654 cur = g1_policy()->collection_set();
2655 while (cur != r) {
2656 HeapRegion* next = cur->next_in_collection_set();
2657 if (cl->doHeapRegion(cur) && false) {
2658 cl->incomplete();
2659 return;
2660 }
2661 cur = next;
2662 }
2663 }
2664
2665 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2666 HeapRegion* result = _hrm.next_region_in_heap(from);
2667 while (result != NULL && result->is_pinned()) {
2668 result = _hrm.next_region_in_heap(result);
2669 }
2670 return result;
2671 }
2672
2673 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2674 HeapRegion* hr = heap_region_containing(addr);
2675 return hr->block_start(addr);
2676 }
2677
2678 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2679 HeapRegion* hr = heap_region_containing(addr);
2680 return hr->block_size(addr);
2681 }
2682
2683 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2684 HeapRegion* hr = heap_region_containing(addr);
2685 return hr->block_is_obj(addr);
2686 }
2687
2688 bool G1CollectedHeap::supports_tlab_allocation() const {
2689 return true;
2690 }
2691
2692 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2693 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2694 }
2695
2696 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2697 return young_list()->eden_used_bytes();
2698 }
2699
2700 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2701 // must be equal to the humongous object limit.
2702 size_t G1CollectedHeap::max_tlab_size() const {
2703 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2704 }
2705
2706 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2707 AllocationContext_t context = AllocationContext::current();
2708 return _allocator->unsafe_max_tlab_alloc(context);
2709 }
2710
2711 size_t G1CollectedHeap::max_capacity() const {
2712 return _hrm.reserved().byte_size();
2713 }
2714
2715 jlong G1CollectedHeap::millis_since_last_gc() {
2716 // assert(false, "NYI");
2717 return 0;
2718 }
2719
2720 void G1CollectedHeap::prepare_for_verify() {
2721 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2722 ensure_parsability(false);
2723 }
2724 g1_rem_set()->prepare_for_verify();
2725 }
2726
2727 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2728 VerifyOption vo) {
2729 switch (vo) {
2730 case VerifyOption_G1UsePrevMarking:
2731 return hr->obj_allocated_since_prev_marking(obj);
2732 case VerifyOption_G1UseNextMarking:
2733 return hr->obj_allocated_since_next_marking(obj);
2734 case VerifyOption_G1UseMarkWord:
2735 return false;
2736 default:
2737 ShouldNotReachHere();
2738 }
2739 return false; // keep some compilers happy
2740 }
2741
2742 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2743 switch (vo) {
2744 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2745 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2746 case VerifyOption_G1UseMarkWord: return NULL;
2747 default: ShouldNotReachHere();
2748 }
2749 return NULL; // keep some compilers happy
2750 }
2751
2752 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2753 switch (vo) {
2754 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2755 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2756 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2757 default: ShouldNotReachHere();
2758 }
2759 return false; // keep some compilers happy
2760 }
2761
2762 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2763 switch (vo) {
2764 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2765 case VerifyOption_G1UseNextMarking: return "NTAMS";
2766 case VerifyOption_G1UseMarkWord: return "NONE";
2767 default: ShouldNotReachHere();
2768 }
2769 return NULL; // keep some compilers happy
2770 }
2771
2772 class VerifyRootsClosure: public OopClosure {
2773 private:
2774 G1CollectedHeap* _g1h;
2775 VerifyOption _vo;
2776 bool _failures;
2777 public:
2778 // _vo == UsePrevMarking -> use "prev" marking information,
2779 // _vo == UseNextMarking -> use "next" marking information,
2780 // _vo == UseMarkWord -> use mark word from object header.
2781 VerifyRootsClosure(VerifyOption vo) :
2782 _g1h(G1CollectedHeap::heap()),
2783 _vo(vo),
2784 _failures(false) { }
2785
2786 bool failures() { return _failures; }
2787
2788 template <class T> void do_oop_nv(T* p) {
2789 T heap_oop = oopDesc::load_heap_oop(p);
2790 if (!oopDesc::is_null(heap_oop)) {
2791 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2792 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2793 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2794 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2795 if (_vo == VerifyOption_G1UseMarkWord) {
2796 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2797 }
2798 obj->print_on(gclog_or_tty);
2799 _failures = true;
2800 }
2801 }
2802 }
2803
2804 void do_oop(oop* p) { do_oop_nv(p); }
2805 void do_oop(narrowOop* p) { do_oop_nv(p); }
2806 };
2807
2808 class G1VerifyCodeRootOopClosure: public OopClosure {
2809 G1CollectedHeap* _g1h;
2810 OopClosure* _root_cl;
2811 nmethod* _nm;
2812 VerifyOption _vo;
2813 bool _failures;
2814
2815 template <class T> void do_oop_work(T* p) {
2816 // First verify that this root is live
2817 _root_cl->do_oop(p);
2818
2819 if (!G1VerifyHeapRegionCodeRoots) {
2820 // We're not verifying the code roots attached to heap region.
2821 return;
2822 }
2823
2824 // Don't check the code roots during marking verification in a full GC
2825 if (_vo == VerifyOption_G1UseMarkWord) {
2826 return;
2827 }
2828
2829 // Now verify that the current nmethod (which contains p) is
2830 // in the code root list of the heap region containing the
2831 // object referenced by p.
2832
2833 T heap_oop = oopDesc::load_heap_oop(p);
2834 if (!oopDesc::is_null(heap_oop)) {
2835 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2836
2837 // Now fetch the region containing the object
2838 HeapRegion* hr = _g1h->heap_region_containing(obj);
2839 HeapRegionRemSet* hrrs = hr->rem_set();
2840 // Verify that the strong code root list for this region
2841 // contains the nmethod
2842 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2843 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2844 "from nmethod " PTR_FORMAT " not in strong "
2845 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2846 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2847 _failures = true;
2848 }
2849 }
2850 }
2851
2852 public:
2853 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2854 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2855
2856 void do_oop(oop* p) { do_oop_work(p); }
2857 void do_oop(narrowOop* p) { do_oop_work(p); }
2858
2859 void set_nmethod(nmethod* nm) { _nm = nm; }
2860 bool failures() { return _failures; }
2861 };
2862
2863 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2864 G1VerifyCodeRootOopClosure* _oop_cl;
2865
2866 public:
2867 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2868 _oop_cl(oop_cl) {}
2869
2870 void do_code_blob(CodeBlob* cb) {
2871 nmethod* nm = cb->as_nmethod_or_null();
2872 if (nm != NULL) {
2873 _oop_cl->set_nmethod(nm);
2874 nm->oops_do(_oop_cl);
2875 }
2876 }
2877 };
2878
2879 class YoungRefCounterClosure : public OopClosure {
2880 G1CollectedHeap* _g1h;
2881 int _count;
2882 public:
2883 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2884 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2885 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2886
2887 int count() { return _count; }
2888 void reset_count() { _count = 0; };
2889 };
2890
2891 class VerifyKlassClosure: public KlassClosure {
2892 YoungRefCounterClosure _young_ref_counter_closure;
2893 OopClosure *_oop_closure;
2894 public:
2895 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2896 void do_klass(Klass* k) {
2897 k->oops_do(_oop_closure);
2898
2899 _young_ref_counter_closure.reset_count();
2900 k->oops_do(&_young_ref_counter_closure);
2901 if (_young_ref_counter_closure.count() > 0) {
2902 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2903 }
2904 }
2905 };
2906
2907 class VerifyLivenessOopClosure: public OopClosure {
2908 G1CollectedHeap* _g1h;
2909 VerifyOption _vo;
2910 public:
2911 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2912 _g1h(g1h), _vo(vo)
2913 { }
2914 void do_oop(narrowOop *p) { do_oop_work(p); }
2915 void do_oop( oop *p) { do_oop_work(p); }
2916
2917 template <class T> void do_oop_work(T *p) {
2918 oop obj = oopDesc::load_decode_heap_oop(p);
2919 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2920 "Dead object referenced by a not dead object");
2921 }
2922 };
2923
2924 class VerifyObjsInRegionClosure: public ObjectClosure {
2925 private:
2926 G1CollectedHeap* _g1h;
2927 size_t _live_bytes;
2928 HeapRegion *_hr;
2929 VerifyOption _vo;
2930 public:
2931 // _vo == UsePrevMarking -> use "prev" marking information,
2932 // _vo == UseNextMarking -> use "next" marking information,
2933 // _vo == UseMarkWord -> use mark word from object header.
2934 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2935 : _live_bytes(0), _hr(hr), _vo(vo) {
2936 _g1h = G1CollectedHeap::heap();
2937 }
2938 void do_object(oop o) {
2939 VerifyLivenessOopClosure isLive(_g1h, _vo);
2940 assert(o != NULL, "Huh?");
2941 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2942 // If the object is alive according to the mark word,
2943 // then verify that the marking information agrees.
2944 // Note we can't verify the contra-positive of the
2945 // above: if the object is dead (according to the mark
2946 // word), it may not be marked, or may have been marked
2947 // but has since became dead, or may have been allocated
2948 // since the last marking.
2949 if (_vo == VerifyOption_G1UseMarkWord) {
2950 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2951 }
2952
2953 o->oop_iterate_no_header(&isLive);
2954 if (!_hr->obj_allocated_since_prev_marking(o)) {
2955 size_t obj_size = o->size(); // Make sure we don't overflow
2956 _live_bytes += (obj_size * HeapWordSize);
2957 }
2958 }
2959 }
2960 size_t live_bytes() { return _live_bytes; }
2961 };
2962
2963 class VerifyArchiveOopClosure: public OopClosure {
2964 public:
2965 VerifyArchiveOopClosure(HeapRegion *hr) { }
2966 void do_oop(narrowOop *p) { do_oop_work(p); }
2967 void do_oop( oop *p) { do_oop_work(p); }
2968
2969 template <class T> void do_oop_work(T *p) {
2970 oop obj = oopDesc::load_decode_heap_oop(p);
2971 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2972 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2973 p2i(p), p2i(obj));
2974 }
2975 };
2976
2977 class VerifyArchiveRegionClosure: public ObjectClosure {
2978 public:
2979 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2980 // Verify that all object pointers are to archive regions.
2981 void do_object(oop o) {
2982 VerifyArchiveOopClosure checkOop(NULL);
2983 assert(o != NULL, "Should not be here for NULL oops");
2984 o->oop_iterate_no_header(&checkOop);
2985 }
2986 };
2987
2988 class VerifyRegionClosure: public HeapRegionClosure {
2989 private:
2990 bool _par;
2991 VerifyOption _vo;
2992 bool _failures;
2993 public:
2994 // _vo == UsePrevMarking -> use "prev" marking information,
2995 // _vo == UseNextMarking -> use "next" marking information,
2996 // _vo == UseMarkWord -> use mark word from object header.
2997 VerifyRegionClosure(bool par, VerifyOption vo)
2998 : _par(par),
2999 _vo(vo),
3000 _failures(false) {}
3001
3002 bool failures() {
3003 return _failures;
3004 }
3005
3006 bool doHeapRegion(HeapRegion* r) {
3007 // For archive regions, verify there are no heap pointers to
3008 // non-pinned regions. For all others, verify liveness info.
3009 if (r->is_archive()) {
3010 VerifyArchiveRegionClosure verify_oop_pointers(r);
3011 r->object_iterate(&verify_oop_pointers);
3012 return true;
3013 }
3014 if (!r->is_continues_humongous()) {
3015 bool failures = false;
3016 r->verify(_vo, &failures);
3017 if (failures) {
3018 _failures = true;
3019 } else if (!r->is_starts_humongous()) {
3020 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3021 r->object_iterate(¬_dead_yet_cl);
3022 if (_vo != VerifyOption_G1UseNextMarking) {
3023 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3024 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3025 "max_live_bytes " SIZE_FORMAT " "
3026 "< calculated " SIZE_FORMAT,
3027 p2i(r->bottom()), p2i(r->end()),
3028 r->max_live_bytes(),
3029 not_dead_yet_cl.live_bytes());
3030 _failures = true;
3031 }
3032 } else {
3033 // When vo == UseNextMarking we cannot currently do a sanity
3034 // check on the live bytes as the calculation has not been
3035 // finalized yet.
3036 }
3037 }
3038 }
3039 return false; // stop the region iteration if we hit a failure
3040 }
3041 };
3042
3043 // This is the task used for parallel verification of the heap regions
3044
3045 class G1ParVerifyTask: public AbstractGangTask {
3046 private:
3047 G1CollectedHeap* _g1h;
3048 VerifyOption _vo;
3049 bool _failures;
3050 HeapRegionClaimer _hrclaimer;
3051
3052 public:
3053 // _vo == UsePrevMarking -> use "prev" marking information,
3054 // _vo == UseNextMarking -> use "next" marking information,
3055 // _vo == UseMarkWord -> use mark word from object header.
3056 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3057 AbstractGangTask("Parallel verify task"),
3058 _g1h(g1h),
3059 _vo(vo),
3060 _failures(false),
3061 _hrclaimer(g1h->workers()->active_workers()) {}
3062
3063 bool failures() {
3064 return _failures;
3065 }
3066
3067 void work(uint worker_id) {
3068 HandleMark hm;
3069 VerifyRegionClosure blk(true, _vo);
3070 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3071 if (blk.failures()) {
3072 _failures = true;
3073 }
3074 }
3075 };
3076
3077 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3078 if (SafepointSynchronize::is_at_safepoint()) {
3079 assert(Thread::current()->is_VM_thread(),
3080 "Expected to be executed serially by the VM thread at this point");
3081
3082 if (!silent) { gclog_or_tty->print("Roots "); }
3083 VerifyRootsClosure rootsCl(vo);
3084 VerifyKlassClosure klassCl(this, &rootsCl);
3085 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3086
3087 // We apply the relevant closures to all the oops in the
3088 // system dictionary, class loader data graph, the string table
3089 // and the nmethods in the code cache.
3090 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3091 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3092
3093 {
3094 G1RootProcessor root_processor(this, 1);
3095 root_processor.process_all_roots(&rootsCl,
3096 &cldCl,
3097 &blobsCl);
3098 }
3099
3100 bool failures = rootsCl.failures() || codeRootsCl.failures();
3101
3102 if (vo != VerifyOption_G1UseMarkWord) {
3103 // If we're verifying during a full GC then the region sets
3104 // will have been torn down at the start of the GC. Therefore
3105 // verifying the region sets will fail. So we only verify
3106 // the region sets when not in a full GC.
3107 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3108 verify_region_sets();
3109 }
3110
3111 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3112 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3113
3114 G1ParVerifyTask task(this, vo);
3115 workers()->run_task(&task);
3116 if (task.failures()) {
3117 failures = true;
3118 }
3119
3120 } else {
3121 VerifyRegionClosure blk(false, vo);
3122 heap_region_iterate(&blk);
3123 if (blk.failures()) {
3124 failures = true;
3125 }
3126 }
3127
3128 if (G1StringDedup::is_enabled()) {
3129 if (!silent) gclog_or_tty->print("StrDedup ");
3130 G1StringDedup::verify();
3131 }
3132
3133 if (failures) {
3134 gclog_or_tty->print_cr("Heap:");
3135 // It helps to have the per-region information in the output to
3136 // help us track down what went wrong. This is why we call
3137 // print_extended_on() instead of print_on().
3138 print_extended_on(gclog_or_tty);
3139 gclog_or_tty->cr();
3140 gclog_or_tty->flush();
3141 }
3142 guarantee(!failures, "there should not have been any failures");
3143 } else {
3144 if (!silent) {
3145 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3146 if (G1StringDedup::is_enabled()) {
3147 gclog_or_tty->print(", StrDedup");
3148 }
3149 gclog_or_tty->print(") ");
3150 }
3151 }
3152 }
3153
3154 void G1CollectedHeap::verify(bool silent) {
3155 verify(silent, VerifyOption_G1UsePrevMarking);
3156 }
3157
3158 double G1CollectedHeap::verify(bool guard, const char* msg) {
3159 double verify_time_ms = 0.0;
3160
3161 if (guard && total_collections() >= VerifyGCStartAt) {
3162 double verify_start = os::elapsedTime();
3163 HandleMark hm; // Discard invalid handles created during verification
3164 prepare_for_verify();
3165 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3166 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3167 }
3168
3169 return verify_time_ms;
3170 }
3171
3172 void G1CollectedHeap::verify_before_gc() {
3173 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3174 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3175 }
3176
3177 void G1CollectedHeap::verify_after_gc() {
3178 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3179 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3180 }
3181
3182 class PrintRegionClosure: public HeapRegionClosure {
3183 outputStream* _st;
3184 public:
3185 PrintRegionClosure(outputStream* st) : _st(st) {}
3186 bool doHeapRegion(HeapRegion* r) {
3187 r->print_on(_st);
3188 return false;
3189 }
3190 };
3191
3192 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3193 const HeapRegion* hr,
3194 const VerifyOption vo) const {
3195 switch (vo) {
3196 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3197 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3198 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3199 default: ShouldNotReachHere();
3200 }
3201 return false; // keep some compilers happy
3202 }
3203
3204 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3205 const VerifyOption vo) const {
3206 switch (vo) {
3207 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3208 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3209 case VerifyOption_G1UseMarkWord: {
3210 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3211 return !obj->is_gc_marked() && !hr->is_archive();
3212 }
3213 default: ShouldNotReachHere();
3214 }
3215 return false; // keep some compilers happy
3216 }
3217
3218 void G1CollectedHeap::print_on(outputStream* st) const {
3219 st->print(" %-20s", "garbage-first heap");
3220 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3221 capacity()/K, used_unlocked()/K);
3222 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3223 p2i(_hrm.reserved().start()),
3224 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3225 p2i(_hrm.reserved().end()));
3226 st->cr();
3227 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3228 uint young_regions = _young_list->length();
3229 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3230 (size_t) young_regions * HeapRegion::GrainBytes / K);
3231 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3232 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3233 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3234 st->cr();
3235 MetaspaceAux::print_on(st);
3236 }
3237
3238 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3239 print_on(st);
3240
3241 // Print the per-region information.
3242 st->cr();
3243 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3244 "HS=humongous(starts), HC=humongous(continues), "
3245 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3246 "PTAMS=previous top-at-mark-start, "
3247 "NTAMS=next top-at-mark-start)");
3248 PrintRegionClosure blk(st);
3249 heap_region_iterate(&blk);
3250 }
3251
3252 void G1CollectedHeap::print_on_error(outputStream* st) const {
3253 this->CollectedHeap::print_on_error(st);
3254
3255 if (_cm != NULL) {
3256 st->cr();
3257 _cm->print_on_error(st);
3258 }
3259 }
3260
3261 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3262 workers()->print_worker_threads_on(st);
3263 _cmThread->print_on(st);
3264 st->cr();
3265 _cm->print_worker_threads_on(st);
3266 _cg1r->print_worker_threads_on(st);
3267 if (G1StringDedup::is_enabled()) {
3268 G1StringDedup::print_worker_threads_on(st);
3269 }
3270 }
3271
3272 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3273 workers()->threads_do(tc);
3274 tc->do_thread(_cmThread);
3275 _cg1r->threads_do(tc);
3276 if (G1StringDedup::is_enabled()) {
3277 G1StringDedup::threads_do(tc);
3278 }
3279 }
3280
3281 void G1CollectedHeap::print_tracing_info() const {
3282 // We'll overload this to mean "trace GC pause statistics."
3283 if (TraceYoungGenTime || TraceOldGenTime) {
3284 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3285 // to that.
3286 g1_policy()->print_tracing_info();
3287 }
3288 if (G1SummarizeRSetStats) {
3289 g1_rem_set()->print_summary_info();
3290 }
3291 if (G1SummarizeConcMark) {
3292 concurrent_mark()->print_summary_info();
3293 }
3294 g1_policy()->print_yg_surv_rate_info();
3295 }
3296
3297 #ifndef PRODUCT
3298 // Helpful for debugging RSet issues.
3299
3300 class PrintRSetsClosure : public HeapRegionClosure {
3301 private:
3302 const char* _msg;
3303 size_t _occupied_sum;
3304
3305 public:
3306 bool doHeapRegion(HeapRegion* r) {
3307 HeapRegionRemSet* hrrs = r->rem_set();
3308 size_t occupied = hrrs->occupied();
3309 _occupied_sum += occupied;
3310
3311 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3312 HR_FORMAT_PARAMS(r));
3313 if (occupied == 0) {
3314 gclog_or_tty->print_cr(" RSet is empty");
3315 } else {
3316 hrrs->print();
3317 }
3318 gclog_or_tty->print_cr("----------");
3319 return false;
3320 }
3321
3322 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3323 gclog_or_tty->cr();
3324 gclog_or_tty->print_cr("========================================");
3325 gclog_or_tty->print_cr("%s", msg);
3326 gclog_or_tty->cr();
3327 }
3328
3329 ~PrintRSetsClosure() {
3330 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3331 gclog_or_tty->print_cr("========================================");
3332 gclog_or_tty->cr();
3333 }
3334 };
3335
3336 void G1CollectedHeap::print_cset_rsets() {
3337 PrintRSetsClosure cl("Printing CSet RSets");
3338 collection_set_iterate(&cl);
3339 }
3340
3341 void G1CollectedHeap::print_all_rsets() {
3342 PrintRSetsClosure cl("Printing All RSets");;
3343 heap_region_iterate(&cl);
3344 }
3345 #endif // PRODUCT
3346
3347 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3348 YoungList* young_list = heap()->young_list();
3349
3350 size_t eden_used_bytes = young_list->eden_used_bytes();
3351 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3352
3353 size_t eden_capacity_bytes =
3354 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3355
3356 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3357 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3358 }
3359
3360 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3361 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3362 stats->unused(), stats->used(), stats->region_end_waste(),
3363 stats->regions_filled(), stats->direct_allocated(),
3364 stats->failure_used(), stats->failure_waste());
3365 }
3366
3367 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3368 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3369 gc_tracer->report_gc_heap_summary(when, heap_summary);
3370
3371 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3372 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3373 }
3374
3375
3376 G1CollectedHeap* G1CollectedHeap::heap() {
3377 CollectedHeap* heap = Universe::heap();
3378 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3379 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3380 return (G1CollectedHeap*)heap;
3381 }
3382
3383 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3384 // always_do_update_barrier = false;
3385 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3386 // Fill TLAB's and such
3387 accumulate_statistics_all_tlabs();
3388 ensure_parsability(true);
3389
3390 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3391 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3392 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3393 }
3394 }
3395
3396 void G1CollectedHeap::gc_epilogue(bool full) {
3397
3398 if (G1SummarizeRSetStats &&
3399 (G1SummarizeRSetStatsPeriod > 0) &&
3400 // we are at the end of the GC. Total collections has already been increased.
3401 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3402 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3403 }
3404
3405 // FIXME: what is this about?
3406 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3407 // is set.
3408 #if defined(COMPILER2) || INCLUDE_JVMCI
3409 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3410 #endif
3411 // always_do_update_barrier = true;
3412
3413 resize_all_tlabs();
3414 allocation_context_stats().update(full);
3415
3416 // We have just completed a GC. Update the soft reference
3417 // policy with the new heap occupancy
3418 Universe::update_heap_info_at_gc();
3419 }
3420
3421 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3422 uint gc_count_before,
3423 bool* succeeded,
3424 GCCause::Cause gc_cause) {
3425 assert_heap_not_locked_and_not_at_safepoint();
3426 g1_policy()->record_stop_world_start();
3427 VM_G1IncCollectionPause op(gc_count_before,
3428 word_size,
3429 false, /* should_initiate_conc_mark */
3430 g1_policy()->max_pause_time_ms(),
3431 gc_cause);
3432
3433 op.set_allocation_context(AllocationContext::current());
3434 VMThread::execute(&op);
3435
3436 HeapWord* result = op.result();
3437 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3438 assert(result == NULL || ret_succeeded,
3439 "the result should be NULL if the VM did not succeed");
3440 *succeeded = ret_succeeded;
3441
3442 assert_heap_not_locked();
3443 return result;
3444 }
3445
3446 void
3447 G1CollectedHeap::doConcurrentMark() {
3448 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3449 if (!_cmThread->in_progress()) {
3450 _cmThread->set_started();
3451 CGC_lock->notify();
3452 }
3453 }
3454
3455 size_t G1CollectedHeap::pending_card_num() {
3456 size_t extra_cards = 0;
3457 JavaThread *curr = Threads::first();
3458 while (curr != NULL) {
3459 DirtyCardQueue& dcq = curr->dirty_card_queue();
3460 extra_cards += dcq.size();
3461 curr = curr->next();
3462 }
3463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3464 size_t buffer_size = dcqs.buffer_size();
3465 size_t buffer_num = dcqs.completed_buffers_num();
3466
3467 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3468 // in bytes - not the number of 'entries'. We need to convert
3469 // into a number of cards.
3470 return (buffer_size * buffer_num + extra_cards) / oopSize;
3471 }
3472
3473 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3474 private:
3475 size_t _total_humongous;
3476 size_t _candidate_humongous;
3477
3478 DirtyCardQueue _dcq;
3479
3480 // We don't nominate objects with many remembered set entries, on
3481 // the assumption that such objects are likely still live.
3482 bool is_remset_small(HeapRegion* region) const {
3483 HeapRegionRemSet* const rset = region->rem_set();
3484 return G1EagerReclaimHumongousObjectsWithStaleRefs
3485 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3486 : rset->is_empty();
3487 }
3488
3489 bool is_typeArray_region(HeapRegion* region) const {
3490 return oop(region->bottom())->is_typeArray();
3491 }
3492
3493 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3494 assert(region->is_starts_humongous(), "Must start a humongous object");
3495
3496 // Candidate selection must satisfy the following constraints
3497 // while concurrent marking is in progress:
3498 //
3499 // * In order to maintain SATB invariants, an object must not be
3500 // reclaimed if it was allocated before the start of marking and
3501 // has not had its references scanned. Such an object must have
3502 // its references (including type metadata) scanned to ensure no
3503 // live objects are missed by the marking process. Objects
3504 // allocated after the start of concurrent marking don't need to
3505 // be scanned.
3506 //
3507 // * An object must not be reclaimed if it is on the concurrent
3508 // mark stack. Objects allocated after the start of concurrent
3509 // marking are never pushed on the mark stack.
3510 //
3511 // Nominating only objects allocated after the start of concurrent
3512 // marking is sufficient to meet both constraints. This may miss
3513 // some objects that satisfy the constraints, but the marking data
3514 // structures don't support efficiently performing the needed
3515 // additional tests or scrubbing of the mark stack.
3516 //
3517 // However, we presently only nominate is_typeArray() objects.
3518 // A humongous object containing references induces remembered
3519 // set entries on other regions. In order to reclaim such an
3520 // object, those remembered sets would need to be cleaned up.
3521 //
3522 // We also treat is_typeArray() objects specially, allowing them
3523 // to be reclaimed even if allocated before the start of
3524 // concurrent mark. For this we rely on mark stack insertion to
3525 // exclude is_typeArray() objects, preventing reclaiming an object
3526 // that is in the mark stack. We also rely on the metadata for
3527 // such objects to be built-in and so ensured to be kept live.
3528 // Frequent allocation and drop of large binary blobs is an
3529 // important use case for eager reclaim, and this special handling
3530 // may reduce needed headroom.
3531
3532 return is_typeArray_region(region) && is_remset_small(region);
3533 }
3534
3535 public:
3536 RegisterHumongousWithInCSetFastTestClosure()
3537 : _total_humongous(0),
3538 _candidate_humongous(0),
3539 _dcq(&JavaThread::dirty_card_queue_set()) {
3540 }
3541
3542 virtual bool doHeapRegion(HeapRegion* r) {
3543 if (!r->is_starts_humongous()) {
3544 return false;
3545 }
3546 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3547
3548 bool is_candidate = humongous_region_is_candidate(g1h, r);
3549 uint rindex = r->hrm_index();
3550 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3551 if (is_candidate) {
3552 _candidate_humongous++;
3553 g1h->register_humongous_region_with_cset(rindex);
3554 // Is_candidate already filters out humongous object with large remembered sets.
3555 // If we have a humongous object with a few remembered sets, we simply flush these
3556 // remembered set entries into the DCQS. That will result in automatic
3557 // re-evaluation of their remembered set entries during the following evacuation
3558 // phase.
3559 if (!r->rem_set()->is_empty()) {
3560 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3561 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3562 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3563 HeapRegionRemSetIterator hrrs(r->rem_set());
3564 size_t card_index;
3565 while (hrrs.has_next(card_index)) {
3566 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3567 // The remembered set might contain references to already freed
3568 // regions. Filter out such entries to avoid failing card table
3569 // verification.
3570 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3571 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3572 *card_ptr = CardTableModRefBS::dirty_card_val();
3573 _dcq.enqueue(card_ptr);
3574 }
3575 }
3576 }
3577 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3578 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3579 hrrs.n_yielded(), r->rem_set()->occupied());
3580 r->rem_set()->clear_locked();
3581 }
3582 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3583 }
3584 _total_humongous++;
3585
3586 return false;
3587 }
3588
3589 size_t total_humongous() const { return _total_humongous; }
3590 size_t candidate_humongous() const { return _candidate_humongous; }
3591
3592 void flush_rem_set_entries() { _dcq.flush(); }
3593 };
3594
3595 void G1CollectedHeap::register_humongous_regions_with_cset() {
3596 if (!G1EagerReclaimHumongousObjects) {
3597 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3598 return;
3599 }
3600 double time = os::elapsed_counter();
3601
3602 // Collect reclaim candidate information and register candidates with cset.
3603 RegisterHumongousWithInCSetFastTestClosure cl;
3604 heap_region_iterate(&cl);
3605
3606 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3607 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3608 cl.total_humongous(),
3609 cl.candidate_humongous());
3610 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3611
3612 // Finally flush all remembered set entries to re-check into the global DCQS.
3613 cl.flush_rem_set_entries();
3614 }
3615
3616 #ifdef ASSERT
3617 class VerifyCSetClosure: public HeapRegionClosure {
3618 public:
3619 bool doHeapRegion(HeapRegion* hr) {
3620 // Here we check that the CSet region's RSet is ready for parallel
3621 // iteration. The fields that we'll verify are only manipulated
3622 // when the region is part of a CSet and is collected. Afterwards,
3623 // we reset these fields when we clear the region's RSet (when the
3624 // region is freed) so they are ready when the region is
3625 // re-allocated. The only exception to this is if there's an
3626 // evacuation failure and instead of freeing the region we leave
3627 // it in the heap. In that case, we reset these fields during
3628 // evacuation failure handling.
3629 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3630
3631 // Here's a good place to add any other checks we'd like to
3632 // perform on CSet regions.
3633 return false;
3634 }
3635 };
3636 #endif // ASSERT
3637
3638 uint G1CollectedHeap::num_task_queues() const {
3639 return _task_queues->size();
3640 }
3641
3642 #if TASKQUEUE_STATS
3643 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3644 st->print_raw_cr("GC Task Stats");
3645 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3646 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3647 }
3648
3649 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3650 print_taskqueue_stats_hdr(st);
3651
3652 TaskQueueStats totals;
3653 const uint n = num_task_queues();
3654 for (uint i = 0; i < n; ++i) {
3655 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3656 totals += task_queue(i)->stats;
3657 }
3658 st->print_raw("tot "); totals.print(st); st->cr();
3659
3660 DEBUG_ONLY(totals.verify());
3661 }
3662
3663 void G1CollectedHeap::reset_taskqueue_stats() {
3664 const uint n = num_task_queues();
3665 for (uint i = 0; i < n; ++i) {
3666 task_queue(i)->stats.reset();
3667 }
3668 }
3669 #endif // TASKQUEUE_STATS
3670
3671 void G1CollectedHeap::log_gc_header() {
3672 if (!G1Log::fine()) {
3673 return;
3674 }
3675
3676 gclog_or_tty->gclog_stamp();
3677
3678 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3679 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3680 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3681
3682 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3683 }
3684
3685 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3686 if (!G1Log::fine()) {
3687 return;
3688 }
3689
3690 if (G1Log::finer()) {
3691 if (evacuation_failed()) {
3692 gclog_or_tty->print(" (to-space exhausted)");
3693 }
3694 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3695 g1_policy()->print_phases(pause_time_sec);
3696 g1_policy()->print_detailed_heap_transition();
3697 } else {
3698 if (evacuation_failed()) {
3699 gclog_or_tty->print("--");
3700 }
3701 g1_policy()->print_heap_transition();
3702 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3703 }
3704 gclog_or_tty->flush();
3705 }
3706
3707 void G1CollectedHeap::wait_for_root_region_scanning() {
3708 double scan_wait_start = os::elapsedTime();
3709 // We have to wait until the CM threads finish scanning the
3710 // root regions as it's the only way to ensure that all the
3711 // objects on them have been correctly scanned before we start
3712 // moving them during the GC.
3713 bool waited = _cm->root_regions()->wait_until_scan_finished();
3714 double wait_time_ms = 0.0;
3715 if (waited) {
3716 double scan_wait_end = os::elapsedTime();
3717 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3718 }
3719 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3720 }
3721
3722 bool
3723 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3724 assert_at_safepoint(true /* should_be_vm_thread */);
3725 guarantee(!is_gc_active(), "collection is not reentrant");
3726
3727 if (GC_locker::check_active_before_gc()) {
3728 return false;
3729 }
3730
3731 _gc_timer_stw->register_gc_start();
3732
3733 GCIdMark gc_id_mark;
3734 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3735
3736 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3737 ResourceMark rm;
3738
3739 wait_for_root_region_scanning();
3740
3741 G1Log::update_level();
3742 print_heap_before_gc();
3743 trace_heap_before_gc(_gc_tracer_stw);
3744
3745 verify_region_sets_optional();
3746 verify_dirty_young_regions();
3747
3748 // This call will decide whether this pause is an initial-mark
3749 // pause. If it is, during_initial_mark_pause() will return true
3750 // for the duration of this pause.
3751 g1_policy()->decide_on_conc_mark_initiation();
3752
3753 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3754 assert(!collector_state()->during_initial_mark_pause() ||
3755 collector_state()->gcs_are_young(), "sanity");
3756
3757 // We also do not allow mixed GCs during marking.
3758 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3759
3760 // Record whether this pause is an initial mark. When the current
3761 // thread has completed its logging output and it's safe to signal
3762 // the CM thread, the flag's value in the policy has been reset.
3763 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3764
3765 // Inner scope for scope based logging, timers, and stats collection
3766 {
3767 EvacuationInfo evacuation_info;
3768
3769 if (collector_state()->during_initial_mark_pause()) {
3770 // We are about to start a marking cycle, so we increment the
3771 // full collection counter.
3772 increment_old_marking_cycles_started();
3773 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3774 }
3775
3776 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3777
3778 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3779
3780 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3781 workers()->active_workers(),
3782 Threads::number_of_non_daemon_threads());
3783 workers()->set_active_workers(active_workers);
3784
3785 double pause_start_sec = os::elapsedTime();
3786 g1_policy()->note_gc_start(active_workers);
3787 log_gc_header();
3788
3789 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3790 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3791
3792 // If the secondary_free_list is not empty, append it to the
3793 // free_list. No need to wait for the cleanup operation to finish;
3794 // the region allocation code will check the secondary_free_list
3795 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3796 // set, skip this step so that the region allocation code has to
3797 // get entries from the secondary_free_list.
3798 if (!G1StressConcRegionFreeing) {
3799 append_secondary_free_list_if_not_empty_with_lock();
3800 }
3801
3802 assert(check_young_list_well_formed(), "young list should be well formed");
3803
3804 // Don't dynamically change the number of GC threads this early. A value of
3805 // 0 is used to indicate serial work. When parallel work is done,
3806 // it will be set.
3807
3808 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3809 IsGCActiveMark x;
3810
3811 gc_prologue(false);
3812 increment_total_collections(false /* full gc */);
3813 increment_gc_time_stamp();
3814
3815 verify_before_gc();
3816
3817 check_bitmaps("GC Start");
3818
3819 #if defined(COMPILER2) || INCLUDE_JVMCI
3820 DerivedPointerTable::clear();
3821 #endif
3822
3823 // Please see comment in g1CollectedHeap.hpp and
3824 // G1CollectedHeap::ref_processing_init() to see how
3825 // reference processing currently works in G1.
3826
3827 // Enable discovery in the STW reference processor
3828 if (g1_policy()->should_process_references()) {
3829 ref_processor_stw()->enable_discovery();
3830 } else {
3831 ref_processor_stw()->disable_discovery();
3832 }
3833
3834 {
3835 // We want to temporarily turn off discovery by the
3836 // CM ref processor, if necessary, and turn it back on
3837 // on again later if we do. Using a scoped
3838 // NoRefDiscovery object will do this.
3839 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3840
3841 // Forget the current alloc region (we might even choose it to be part
3842 // of the collection set!).
3843 _allocator->release_mutator_alloc_region();
3844
3845 // We should call this after we retire the mutator alloc
3846 // region(s) so that all the ALLOC / RETIRE events are generated
3847 // before the start GC event.
3848 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3849
3850 // This timing is only used by the ergonomics to handle our pause target.
3851 // It is unclear why this should not include the full pause. We will
3852 // investigate this in CR 7178365.
3853 //
3854 // Preserving the old comment here if that helps the investigation:
3855 //
3856 // The elapsed time induced by the start time below deliberately elides
3857 // the possible verification above.
3858 double sample_start_time_sec = os::elapsedTime();
3859
3860 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3861
3862 if (collector_state()->during_initial_mark_pause()) {
3863 concurrent_mark()->checkpointRootsInitialPre();
3864 }
3865
3866 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3867 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3868
3869 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3870
3871 // Make sure the remembered sets are up to date. This needs to be
3872 // done before register_humongous_regions_with_cset(), because the
3873 // remembered sets are used there to choose eager reclaim candidates.
3874 // If the remembered sets are not up to date we might miss some
3875 // entries that need to be handled.
3876 g1_rem_set()->cleanupHRRS();
3877
3878 register_humongous_regions_with_cset();
3879
3880 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3881
3882 _cm->note_start_of_gc();
3883 // We call this after finalize_cset() to
3884 // ensure that the CSet has been finalized.
3885 _cm->verify_no_cset_oops();
3886
3887 if (_hr_printer.is_active()) {
3888 HeapRegion* hr = g1_policy()->collection_set();
3889 while (hr != NULL) {
3890 _hr_printer.cset(hr);
3891 hr = hr->next_in_collection_set();
3892 }
3893 }
3894
3895 #ifdef ASSERT
3896 VerifyCSetClosure cl;
3897 collection_set_iterate(&cl);
3898 #endif // ASSERT
3899
3900 // Initialize the GC alloc regions.
3901 _allocator->init_gc_alloc_regions(evacuation_info);
3902
3903 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3904 pre_evacuate_collection_set();
3905
3906 // Actually do the work...
3907 evacuate_collection_set(evacuation_info, &per_thread_states);
3908
3909 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3910
3911 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3912 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3913
3914 eagerly_reclaim_humongous_regions();
3915
3916 g1_policy()->clear_collection_set();
3917
3918 // Start a new incremental collection set for the next pause.
3919 g1_policy()->start_incremental_cset_building();
3920
3921 clear_cset_fast_test();
3922
3923 _young_list->reset_sampled_info();
3924
3925 // Don't check the whole heap at this point as the
3926 // GC alloc regions from this pause have been tagged
3927 // as survivors and moved on to the survivor list.
3928 // Survivor regions will fail the !is_young() check.
3929 assert(check_young_list_empty(false /* check_heap */),
3930 "young list should be empty");
3931
3932 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3933 _young_list->first_survivor_region(),
3934 _young_list->last_survivor_region());
3935
3936 _young_list->reset_auxilary_lists();
3937
3938 if (evacuation_failed()) {
3939 set_used(recalculate_used());
3940 if (_archive_allocator != NULL) {
3941 _archive_allocator->clear_used();
3942 }
3943 for (uint i = 0; i < ParallelGCThreads; i++) {
3944 if (_evacuation_failed_info_array[i].has_failed()) {
3945 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3946 }
3947 }
3948 } else {
3949 // The "used" of the the collection set have already been subtracted
3950 // when they were freed. Add in the bytes evacuated.
3951 increase_used(g1_policy()->bytes_copied_during_gc());
3952 }
3953
3954 if (collector_state()->during_initial_mark_pause()) {
3955 // We have to do this before we notify the CM threads that
3956 // they can start working to make sure that all the
3957 // appropriate initialization is done on the CM object.
3958 concurrent_mark()->checkpointRootsInitialPost();
3959 collector_state()->set_mark_in_progress(true);
3960 // Note that we don't actually trigger the CM thread at
3961 // this point. We do that later when we're sure that
3962 // the current thread has completed its logging output.
3963 }
3964
3965 allocate_dummy_regions();
3966
3967 _allocator->init_mutator_alloc_region();
3968
3969 {
3970 size_t expand_bytes = g1_policy()->expansion_amount();
3971 if (expand_bytes > 0) {
3972 size_t bytes_before = capacity();
3973 // No need for an ergo verbose message here,
3974 // expansion_amount() does this when it returns a value > 0.
3975 double expand_ms;
3976 if (!expand(expand_bytes, &expand_ms)) {
3977 // We failed to expand the heap. Cannot do anything about it.
3978 }
3979 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3980 }
3981 }
3982
3983 // We redo the verification but now wrt to the new CSet which
3984 // has just got initialized after the previous CSet was freed.
3985 _cm->verify_no_cset_oops();
3986 _cm->note_end_of_gc();
3987
3988 // This timing is only used by the ergonomics to handle our pause target.
3989 // It is unclear why this should not include the full pause. We will
3990 // investigate this in CR 7178365.
3991 double sample_end_time_sec = os::elapsedTime();
3992 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3993 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3994 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3995
3996 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3997 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3998
3999 MemoryService::track_memory_usage();
4000
4001 // In prepare_for_verify() below we'll need to scan the deferred
4002 // update buffers to bring the RSets up-to-date if
4003 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4004 // the update buffers we'll probably need to scan cards on the
4005 // regions we just allocated to (i.e., the GC alloc
4006 // regions). However, during the last GC we called
4007 // set_saved_mark() on all the GC alloc regions, so card
4008 // scanning might skip the [saved_mark_word()...top()] area of
4009 // those regions (i.e., the area we allocated objects into
4010 // during the last GC). But it shouldn't. Given that
4011 // saved_mark_word() is conditional on whether the GC time stamp
4012 // on the region is current or not, by incrementing the GC time
4013 // stamp here we invalidate all the GC time stamps on all the
4014 // regions and saved_mark_word() will simply return top() for
4015 // all the regions. This is a nicer way of ensuring this rather
4016 // than iterating over the regions and fixing them. In fact, the
4017 // GC time stamp increment here also ensures that
4018 // saved_mark_word() will return top() between pauses, i.e.,
4019 // during concurrent refinement. So we don't need the
4020 // is_gc_active() check to decided which top to use when
4021 // scanning cards (see CR 7039627).
4022 increment_gc_time_stamp();
4023
4024 verify_after_gc();
4025 check_bitmaps("GC End");
4026
4027 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4028 ref_processor_stw()->verify_no_references_recorded();
4029
4030 // CM reference discovery will be re-enabled if necessary.
4031 }
4032
4033 // We should do this after we potentially expand the heap so
4034 // that all the COMMIT events are generated before the end GC
4035 // event, and after we retire the GC alloc regions so that all
4036 // RETIRE events are generated before the end GC event.
4037 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4038
4039 #ifdef TRACESPINNING
4040 ParallelTaskTerminator::print_termination_counts();
4041 #endif
4042
4043 gc_epilogue(false);
4044 }
4045
4046 // Print the remainder of the GC log output.
4047 log_gc_footer(os::elapsedTime() - pause_start_sec);
4048
4049 // It is not yet to safe to tell the concurrent mark to
4050 // start as we have some optional output below. We don't want the
4051 // output from the concurrent mark thread interfering with this
4052 // logging output either.
4053
4054 _hrm.verify_optional();
4055 verify_region_sets_optional();
4056
4057 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4058 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4059
4060 print_heap_after_gc();
4061 trace_heap_after_gc(_gc_tracer_stw);
4062
4063 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4064 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4065 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4066 // before any GC notifications are raised.
4067 g1mm()->update_sizes();
4068
4069 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4070 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4071 _gc_timer_stw->register_gc_end();
4072 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4073 }
4074 // It should now be safe to tell the concurrent mark thread to start
4075 // without its logging output interfering with the logging output
4076 // that came from the pause.
4077
4078 if (should_start_conc_mark) {
4079 // CAUTION: after the doConcurrentMark() call below,
4080 // the concurrent marking thread(s) could be running
4081 // concurrently with us. Make sure that anything after
4082 // this point does not assume that we are the only GC thread
4083 // running. Note: of course, the actual marking work will
4084 // not start until the safepoint itself is released in
4085 // SuspendibleThreadSet::desynchronize().
4086 doConcurrentMark();
4087 }
4088
4089 return true;
4090 }
4091
4092 void G1CollectedHeap::restore_preserved_marks() {
4093 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
4094 workers()->run_task(&rpm_task);
4095 }
4096
4097 void G1CollectedHeap::remove_self_forwarding_pointers() {
4098 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4099 workers()->run_task(&rsfp_task);
4100 }
4101
4102 void G1CollectedHeap::restore_after_evac_failure() {
4103 double remove_self_forwards_start = os::elapsedTime();
4104
4105 remove_self_forwarding_pointers();
4106 restore_preserved_marks();
4107
4108 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4109 }
4110
4111 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4112 if (!_evacuation_failed) {
4113 _evacuation_failed = true;
4114 }
4115
4116 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4117
4118 // We want to call the "for_promotion_failure" version only in the
4119 // case of a promotion failure.
4120 if (m->must_be_preserved_for_promotion_failure(obj)) {
4121 OopAndMarkOop elem(obj, m);
4122 _preserved_objs[worker_id].push(elem);
4123 }
4124 }
4125
4126 bool G1ParEvacuateFollowersClosure::offer_termination() {
4127 G1ParScanThreadState* const pss = par_scan_state();
4128 start_term_time();
4129 const bool res = terminator()->offer_termination();
4130 end_term_time();
4131 return res;
4132 }
4133
4134 void G1ParEvacuateFollowersClosure::do_void() {
4135 G1ParScanThreadState* const pss = par_scan_state();
4136 pss->trim_queue();
4137 do {
4138 pss->steal_and_trim_queue(queues());
4139 } while (!offer_termination());
4140 }
4141
4142 class G1ParTask : public AbstractGangTask {
4143 protected:
4144 G1CollectedHeap* _g1h;
4145 G1ParScanThreadStateSet* _pss;
4146 RefToScanQueueSet* _queues;
4147 G1RootProcessor* _root_processor;
4148 ParallelTaskTerminator _terminator;
4149 uint _n_workers;
4150
4151 public:
4152 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4153 : AbstractGangTask("G1 collection"),
4154 _g1h(g1h),
4155 _pss(per_thread_states),
4156 _queues(task_queues),
4157 _root_processor(root_processor),
4158 _terminator(n_workers, _queues),
4159 _n_workers(n_workers)
4160 {}
4161
4162 void work(uint worker_id) {
4163 if (worker_id >= _n_workers) return; // no work needed this round
4164
4165 double start_sec = os::elapsedTime();
4166 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4167
4168 {
4169 ResourceMark rm;
4170 HandleMark hm;
4171
4172 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4173
4174 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4175 pss->set_ref_processor(rp);
4176
4177 double start_strong_roots_sec = os::elapsedTime();
4178
4179 _root_processor->evacuate_roots(pss->closures(), worker_id);
4180
4181 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4182
4183 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4184 // treating the nmethods visited to act as roots for concurrent marking.
4185 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4186 // objects copied by the current evacuation.
4187 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4188 pss->closures()->weak_codeblobs(),
4189 worker_id);
4190
4191 _pss->add_cards_scanned(worker_id, cards_scanned);
4192
4193 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4194
4195 double term_sec = 0.0;
4196 size_t evac_term_attempts = 0;
4197 {
4198 double start = os::elapsedTime();
4199 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4200 evac.do_void();
4201
4202 evac_term_attempts = evac.term_attempts();
4203 term_sec = evac.term_time();
4204 double elapsed_sec = os::elapsedTime() - start;
4205 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4206 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4207 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4208 }
4209
4210 assert(pss->queue_is_empty(), "should be empty");
4211
4212 if (PrintTerminationStats) {
4213 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4214 size_t lab_waste;
4215 size_t lab_undo_waste;
4216 pss->waste(lab_waste, lab_undo_waste);
4217 _g1h->print_termination_stats(gclog_or_tty,
4218 worker_id,
4219 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4220 strong_roots_sec * 1000.0, /* strong roots time */
4221 term_sec * 1000.0, /* evac term time */
4222 evac_term_attempts, /* evac term attempts */
4223 lab_waste, /* alloc buffer waste */
4224 lab_undo_waste /* undo waste */
4225 );
4226 }
4227
4228 // Close the inner scope so that the ResourceMark and HandleMark
4229 // destructors are executed here and are included as part of the
4230 // "GC Worker Time".
4231 }
4232 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4233 }
4234 };
4235
4236 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4237 st->print_raw_cr("GC Termination Stats");
4238 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4239 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4240 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4241 }
4242
4243 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4244 uint worker_id,
4245 double elapsed_ms,
4246 double strong_roots_ms,
4247 double term_ms,
4248 size_t term_attempts,
4249 size_t alloc_buffer_waste,
4250 size_t undo_waste) const {
4251 st->print_cr("%3d %9.2f %9.2f %6.2f "
4252 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4253 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4254 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4255 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4256 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4257 alloc_buffer_waste * HeapWordSize / K,
4258 undo_waste * HeapWordSize / K);
4259 }
4260
4261 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4262 private:
4263 BoolObjectClosure* _is_alive;
4264 int _initial_string_table_size;
4265 int _initial_symbol_table_size;
4266
4267 bool _process_strings;
4268 int _strings_processed;
4269 int _strings_removed;
4270
4271 bool _process_symbols;
4272 int _symbols_processed;
4273 int _symbols_removed;
4274
4275 public:
4276 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4277 AbstractGangTask("String/Symbol Unlinking"),
4278 _is_alive(is_alive),
4279 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4280 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4281
4282 _initial_string_table_size = StringTable::the_table()->table_size();
4283 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4284 if (process_strings) {
4285 StringTable::clear_parallel_claimed_index();
4286 }
4287 if (process_symbols) {
4288 SymbolTable::clear_parallel_claimed_index();
4289 }
4290 }
4291
4292 ~G1StringSymbolTableUnlinkTask() {
4293 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4294 "claim value %d after unlink less than initial string table size %d",
4295 StringTable::parallel_claimed_index(), _initial_string_table_size);
4296 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4297 "claim value %d after unlink less than initial symbol table size %d",
4298 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4299
4300 if (G1TraceStringSymbolTableScrubbing) {
4301 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4302 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4303 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4304 strings_processed(), strings_removed(),
4305 symbols_processed(), symbols_removed());
4306 }
4307 }
4308
4309 void work(uint worker_id) {
4310 int strings_processed = 0;
4311 int strings_removed = 0;
4312 int symbols_processed = 0;
4313 int symbols_removed = 0;
4314 if (_process_strings) {
4315 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4316 Atomic::add(strings_processed, &_strings_processed);
4317 Atomic::add(strings_removed, &_strings_removed);
4318 }
4319 if (_process_symbols) {
4320 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4321 Atomic::add(symbols_processed, &_symbols_processed);
4322 Atomic::add(symbols_removed, &_symbols_removed);
4323 }
4324 }
4325
4326 size_t strings_processed() const { return (size_t)_strings_processed; }
4327 size_t strings_removed() const { return (size_t)_strings_removed; }
4328
4329 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4330 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4331 };
4332
4333 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4334 private:
4335 static Monitor* _lock;
4336
4337 BoolObjectClosure* const _is_alive;
4338 const bool _unloading_occurred;
4339 const uint _num_workers;
4340
4341 // Variables used to claim nmethods.
4342 nmethod* _first_nmethod;
4343 volatile nmethod* _claimed_nmethod;
4344
4345 // The list of nmethods that need to be processed by the second pass.
4346 volatile nmethod* _postponed_list;
4347 volatile uint _num_entered_barrier;
4348
4349 public:
4350 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4351 _is_alive(is_alive),
4352 _unloading_occurred(unloading_occurred),
4353 _num_workers(num_workers),
4354 _first_nmethod(NULL),
4355 _claimed_nmethod(NULL),
4356 _postponed_list(NULL),
4357 _num_entered_barrier(0)
4358 {
4359 nmethod::increase_unloading_clock();
4360 // Get first alive nmethod
4361 NMethodIterator iter = NMethodIterator();
4362 if(iter.next_alive()) {
4363 _first_nmethod = iter.method();
4364 }
4365 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4366 }
4367
4368 ~G1CodeCacheUnloadingTask() {
4369 CodeCache::verify_clean_inline_caches();
4370
4371 CodeCache::set_needs_cache_clean(false);
4372 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4373
4374 CodeCache::verify_icholder_relocations();
4375 }
4376
4377 private:
4378 void add_to_postponed_list(nmethod* nm) {
4379 nmethod* old;
4380 do {
4381 old = (nmethod*)_postponed_list;
4382 nm->set_unloading_next(old);
4383 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4384 }
4385
4386 void clean_nmethod(nmethod* nm) {
4387 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4388
4389 if (postponed) {
4390 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4391 add_to_postponed_list(nm);
4392 }
4393
4394 // Mark that this thread has been cleaned/unloaded.
4395 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4396 nm->set_unloading_clock(nmethod::global_unloading_clock());
4397 }
4398
4399 void clean_nmethod_postponed(nmethod* nm) {
4400 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4401 }
4402
4403 static const int MaxClaimNmethods = 16;
4404
4405 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4406 nmethod* first;
4407 NMethodIterator last;
4408
4409 do {
4410 *num_claimed_nmethods = 0;
4411
4412 first = (nmethod*)_claimed_nmethod;
4413 last = NMethodIterator(first);
4414
4415 if (first != NULL) {
4416
4417 for (int i = 0; i < MaxClaimNmethods; i++) {
4418 if (!last.next_alive()) {
4419 break;
4420 }
4421 claimed_nmethods[i] = last.method();
4422 (*num_claimed_nmethods)++;
4423 }
4424 }
4425
4426 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4427 }
4428
4429 nmethod* claim_postponed_nmethod() {
4430 nmethod* claim;
4431 nmethod* next;
4432
4433 do {
4434 claim = (nmethod*)_postponed_list;
4435 if (claim == NULL) {
4436 return NULL;
4437 }
4438
4439 next = claim->unloading_next();
4440
4441 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4442
4443 return claim;
4444 }
4445
4446 public:
4447 // Mark that we're done with the first pass of nmethod cleaning.
4448 void barrier_mark(uint worker_id) {
4449 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4450 _num_entered_barrier++;
4451 if (_num_entered_barrier == _num_workers) {
4452 ml.notify_all();
4453 }
4454 }
4455
4456 // See if we have to wait for the other workers to
4457 // finish their first-pass nmethod cleaning work.
4458 void barrier_wait(uint worker_id) {
4459 if (_num_entered_barrier < _num_workers) {
4460 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4461 while (_num_entered_barrier < _num_workers) {
4462 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4463 }
4464 }
4465 }
4466
4467 // Cleaning and unloading of nmethods. Some work has to be postponed
4468 // to the second pass, when we know which nmethods survive.
4469 void work_first_pass(uint worker_id) {
4470 // The first nmethods is claimed by the first worker.
4471 if (worker_id == 0 && _first_nmethod != NULL) {
4472 clean_nmethod(_first_nmethod);
4473 _first_nmethod = NULL;
4474 }
4475
4476 int num_claimed_nmethods;
4477 nmethod* claimed_nmethods[MaxClaimNmethods];
4478
4479 while (true) {
4480 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4481
4482 if (num_claimed_nmethods == 0) {
4483 break;
4484 }
4485
4486 for (int i = 0; i < num_claimed_nmethods; i++) {
4487 clean_nmethod(claimed_nmethods[i]);
4488 }
4489 }
4490 }
4491
4492 void work_second_pass(uint worker_id) {
4493 nmethod* nm;
4494 // Take care of postponed nmethods.
4495 while ((nm = claim_postponed_nmethod()) != NULL) {
4496 clean_nmethod_postponed(nm);
4497 }
4498 }
4499 };
4500
4501 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4502
4503 class G1KlassCleaningTask : public StackObj {
4504 BoolObjectClosure* _is_alive;
4505 volatile jint _clean_klass_tree_claimed;
4506 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4507
4508 public:
4509 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4510 _is_alive(is_alive),
4511 _clean_klass_tree_claimed(0),
4512 _klass_iterator() {
4513 }
4514
4515 private:
4516 bool claim_clean_klass_tree_task() {
4517 if (_clean_klass_tree_claimed) {
4518 return false;
4519 }
4520
4521 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4522 }
4523
4524 InstanceKlass* claim_next_klass() {
4525 Klass* klass;
4526 do {
4527 klass =_klass_iterator.next_klass();
4528 } while (klass != NULL && !klass->is_instance_klass());
4529
4530 // this can be null so don't call InstanceKlass::cast
4531 return static_cast<InstanceKlass*>(klass);
4532 }
4533
4534 public:
4535
4536 void clean_klass(InstanceKlass* ik) {
4537 ik->clean_weak_instanceklass_links(_is_alive);
4538 }
4539
4540 void work() {
4541 ResourceMark rm;
4542
4543 // One worker will clean the subklass/sibling klass tree.
4544 if (claim_clean_klass_tree_task()) {
4545 Klass::clean_subklass_tree(_is_alive);
4546 }
4547
4548 // All workers will help cleaning the classes,
4549 InstanceKlass* klass;
4550 while ((klass = claim_next_klass()) != NULL) {
4551 clean_klass(klass);
4552 }
4553 }
4554 };
4555
4556 // To minimize the remark pause times, the tasks below are done in parallel.
4557 class G1ParallelCleaningTask : public AbstractGangTask {
4558 private:
4559 G1StringSymbolTableUnlinkTask _string_symbol_task;
4560 G1CodeCacheUnloadingTask _code_cache_task;
4561 G1KlassCleaningTask _klass_cleaning_task;
4562
4563 public:
4564 // The constructor is run in the VMThread.
4565 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4566 AbstractGangTask("Parallel Cleaning"),
4567 _string_symbol_task(is_alive, process_strings, process_symbols),
4568 _code_cache_task(num_workers, is_alive, unloading_occurred),
4569 _klass_cleaning_task(is_alive) {
4570 }
4571
4572 // The parallel work done by all worker threads.
4573 void work(uint worker_id) {
4574 // Do first pass of code cache cleaning.
4575 _code_cache_task.work_first_pass(worker_id);
4576
4577 // Let the threads mark that the first pass is done.
4578 _code_cache_task.barrier_mark(worker_id);
4579
4580 // Clean the Strings and Symbols.
4581 _string_symbol_task.work(worker_id);
4582
4583 // Wait for all workers to finish the first code cache cleaning pass.
4584 _code_cache_task.barrier_wait(worker_id);
4585
4586 // Do the second code cache cleaning work, which realize on
4587 // the liveness information gathered during the first pass.
4588 _code_cache_task.work_second_pass(worker_id);
4589
4590 // Clean all klasses that were not unloaded.
4591 _klass_cleaning_task.work();
4592 }
4593 };
4594
4595
4596 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4597 bool process_strings,
4598 bool process_symbols,
4599 bool class_unloading_occurred) {
4600 uint n_workers = workers()->active_workers();
4601
4602 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4603 n_workers, class_unloading_occurred);
4604 workers()->run_task(&g1_unlink_task);
4605 }
4606
4607 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4608 bool process_strings, bool process_symbols) {
4609 {
4610 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4611 workers()->run_task(&g1_unlink_task);
4612 }
4613
4614 if (G1StringDedup::is_enabled()) {
4615 G1StringDedup::unlink(is_alive);
4616 }
4617 }
4618
4619 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4620 private:
4621 DirtyCardQueueSet* _queue;
4622 public:
4623 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4624
4625 virtual void work(uint worker_id) {
4626 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4627 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4628
4629 RedirtyLoggedCardTableEntryClosure cl;
4630 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4631
4632 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4633 }
4634 };
4635
4636 void G1CollectedHeap::redirty_logged_cards() {
4637 double redirty_logged_cards_start = os::elapsedTime();
4638
4639 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4640 dirty_card_queue_set().reset_for_par_iteration();
4641 workers()->run_task(&redirty_task);
4642
4643 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4644 dcq.merge_bufferlists(&dirty_card_queue_set());
4645 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4646
4647 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4648 }
4649
4650 // Weak Reference Processing support
4651
4652 // An always "is_alive" closure that is used to preserve referents.
4653 // If the object is non-null then it's alive. Used in the preservation
4654 // of referent objects that are pointed to by reference objects
4655 // discovered by the CM ref processor.
4656 class G1AlwaysAliveClosure: public BoolObjectClosure {
4657 G1CollectedHeap* _g1;
4658 public:
4659 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4660 bool do_object_b(oop p) {
4661 if (p != NULL) {
4662 return true;
4663 }
4664 return false;
4665 }
4666 };
4667
4668 bool G1STWIsAliveClosure::do_object_b(oop p) {
4669 // An object is reachable if it is outside the collection set,
4670 // or is inside and copied.
4671 return !_g1->is_in_cset(p) || p->is_forwarded();
4672 }
4673
4674 // Non Copying Keep Alive closure
4675 class G1KeepAliveClosure: public OopClosure {
4676 G1CollectedHeap* _g1;
4677 public:
4678 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4679 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4680 void do_oop(oop* p) {
4681 oop obj = *p;
4682 assert(obj != NULL, "the caller should have filtered out NULL values");
4683
4684 const InCSetState cset_state = _g1->in_cset_state(obj);
4685 if (!cset_state.is_in_cset_or_humongous()) {
4686 return;
4687 }
4688 if (cset_state.is_in_cset()) {
4689 assert( obj->is_forwarded(), "invariant" );
4690 *p = obj->forwardee();
4691 } else {
4692 assert(!obj->is_forwarded(), "invariant" );
4693 assert(cset_state.is_humongous(),
4694 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4695 _g1->set_humongous_is_live(obj);
4696 }
4697 }
4698 };
4699
4700 // Copying Keep Alive closure - can be called from both
4701 // serial and parallel code as long as different worker
4702 // threads utilize different G1ParScanThreadState instances
4703 // and different queues.
4704
4705 class G1CopyingKeepAliveClosure: public OopClosure {
4706 G1CollectedHeap* _g1h;
4707 OopClosure* _copy_non_heap_obj_cl;
4708 G1ParScanThreadState* _par_scan_state;
4709
4710 public:
4711 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4712 OopClosure* non_heap_obj_cl,
4713 G1ParScanThreadState* pss):
4714 _g1h(g1h),
4715 _copy_non_heap_obj_cl(non_heap_obj_cl),
4716 _par_scan_state(pss)
4717 {}
4718
4719 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4720 virtual void do_oop( oop* p) { do_oop_work(p); }
4721
4722 template <class T> void do_oop_work(T* p) {
4723 oop obj = oopDesc::load_decode_heap_oop(p);
4724
4725 if (_g1h->is_in_cset_or_humongous(obj)) {
4726 // If the referent object has been forwarded (either copied
4727 // to a new location or to itself in the event of an
4728 // evacuation failure) then we need to update the reference
4729 // field and, if both reference and referent are in the G1
4730 // heap, update the RSet for the referent.
4731 //
4732 // If the referent has not been forwarded then we have to keep
4733 // it alive by policy. Therefore we have copy the referent.
4734 //
4735 // If the reference field is in the G1 heap then we can push
4736 // on the PSS queue. When the queue is drained (after each
4737 // phase of reference processing) the object and it's followers
4738 // will be copied, the reference field set to point to the
4739 // new location, and the RSet updated. Otherwise we need to
4740 // use the the non-heap or metadata closures directly to copy
4741 // the referent object and update the pointer, while avoiding
4742 // updating the RSet.
4743
4744 if (_g1h->is_in_g1_reserved(p)) {
4745 _par_scan_state->push_on_queue(p);
4746 } else {
4747 assert(!Metaspace::contains((const void*)p),
4748 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4749 _copy_non_heap_obj_cl->do_oop(p);
4750 }
4751 }
4752 }
4753 };
4754
4755 // Serial drain queue closure. Called as the 'complete_gc'
4756 // closure for each discovered list in some of the
4757 // reference processing phases.
4758
4759 class G1STWDrainQueueClosure: public VoidClosure {
4760 protected:
4761 G1CollectedHeap* _g1h;
4762 G1ParScanThreadState* _par_scan_state;
4763
4764 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4765
4766 public:
4767 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4768 _g1h(g1h),
4769 _par_scan_state(pss)
4770 { }
4771
4772 void do_void() {
4773 G1ParScanThreadState* const pss = par_scan_state();
4774 pss->trim_queue();
4775 }
4776 };
4777
4778 // Parallel Reference Processing closures
4779
4780 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4781 // processing during G1 evacuation pauses.
4782
4783 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4784 private:
4785 G1CollectedHeap* _g1h;
4786 G1ParScanThreadStateSet* _pss;
4787 RefToScanQueueSet* _queues;
4788 WorkGang* _workers;
4789 uint _active_workers;
4790
4791 public:
4792 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4793 G1ParScanThreadStateSet* per_thread_states,
4794 WorkGang* workers,
4795 RefToScanQueueSet *task_queues,
4796 uint n_workers) :
4797 _g1h(g1h),
4798 _pss(per_thread_states),
4799 _queues(task_queues),
4800 _workers(workers),
4801 _active_workers(n_workers)
4802 {
4803 assert(n_workers > 0, "shouldn't call this otherwise");
4804 }
4805
4806 // Executes the given task using concurrent marking worker threads.
4807 virtual void execute(ProcessTask& task);
4808 virtual void execute(EnqueueTask& task);
4809 };
4810
4811 // Gang task for possibly parallel reference processing
4812
4813 class G1STWRefProcTaskProxy: public AbstractGangTask {
4814 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4815 ProcessTask& _proc_task;
4816 G1CollectedHeap* _g1h;
4817 G1ParScanThreadStateSet* _pss;
4818 RefToScanQueueSet* _task_queues;
4819 ParallelTaskTerminator* _terminator;
4820
4821 public:
4822 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4823 G1CollectedHeap* g1h,
4824 G1ParScanThreadStateSet* per_thread_states,
4825 RefToScanQueueSet *task_queues,
4826 ParallelTaskTerminator* terminator) :
4827 AbstractGangTask("Process reference objects in parallel"),
4828 _proc_task(proc_task),
4829 _g1h(g1h),
4830 _pss(per_thread_states),
4831 _task_queues(task_queues),
4832 _terminator(terminator)
4833 {}
4834
4835 virtual void work(uint worker_id) {
4836 // The reference processing task executed by a single worker.
4837 ResourceMark rm;
4838 HandleMark hm;
4839
4840 G1STWIsAliveClosure is_alive(_g1h);
4841
4842 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4843 pss->set_ref_processor(NULL);
4844
4845 // Keep alive closure.
4846 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4847
4848 // Complete GC closure
4849 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4850
4851 // Call the reference processing task's work routine.
4852 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4853
4854 // Note we cannot assert that the refs array is empty here as not all
4855 // of the processing tasks (specifically phase2 - pp2_work) execute
4856 // the complete_gc closure (which ordinarily would drain the queue) so
4857 // the queue may not be empty.
4858 }
4859 };
4860
4861 // Driver routine for parallel reference processing.
4862 // Creates an instance of the ref processing gang
4863 // task and has the worker threads execute it.
4864 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4865 assert(_workers != NULL, "Need parallel worker threads.");
4866
4867 ParallelTaskTerminator terminator(_active_workers, _queues);
4868 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4869
4870 _workers->run_task(&proc_task_proxy);
4871 }
4872
4873 // Gang task for parallel reference enqueueing.
4874
4875 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4876 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4877 EnqueueTask& _enq_task;
4878
4879 public:
4880 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4881 AbstractGangTask("Enqueue reference objects in parallel"),
4882 _enq_task(enq_task)
4883 { }
4884
4885 virtual void work(uint worker_id) {
4886 _enq_task.work(worker_id);
4887 }
4888 };
4889
4890 // Driver routine for parallel reference enqueueing.
4891 // Creates an instance of the ref enqueueing gang
4892 // task and has the worker threads execute it.
4893
4894 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4895 assert(_workers != NULL, "Need parallel worker threads.");
4896
4897 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4898
4899 _workers->run_task(&enq_task_proxy);
4900 }
4901
4902 // End of weak reference support closures
4903
4904 // Abstract task used to preserve (i.e. copy) any referent objects
4905 // that are in the collection set and are pointed to by reference
4906 // objects discovered by the CM ref processor.
4907
4908 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4909 protected:
4910 G1CollectedHeap* _g1h;
4911 G1ParScanThreadStateSet* _pss;
4912 RefToScanQueueSet* _queues;
4913 ParallelTaskTerminator _terminator;
4914 uint _n_workers;
4915
4916 public:
4917 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4918 AbstractGangTask("ParPreserveCMReferents"),
4919 _g1h(g1h),
4920 _pss(per_thread_states),
4921 _queues(task_queues),
4922 _terminator(workers, _queues),
4923 _n_workers(workers)
4924 { }
4925
4926 void work(uint worker_id) {
4927 ResourceMark rm;
4928 HandleMark hm;
4929
4930 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4931 pss->set_ref_processor(NULL);
4932 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4933
4934 // Is alive closure
4935 G1AlwaysAliveClosure always_alive(_g1h);
4936
4937 // Copying keep alive closure. Applied to referent objects that need
4938 // to be copied.
4939 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4940
4941 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4942
4943 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4944 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4945
4946 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4947 // So this must be true - but assert just in case someone decides to
4948 // change the worker ids.
4949 assert(worker_id < limit, "sanity");
4950 assert(!rp->discovery_is_atomic(), "check this code");
4951
4952 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4953 for (uint idx = worker_id; idx < limit; idx += stride) {
4954 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4955
4956 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4957 while (iter.has_next()) {
4958 // Since discovery is not atomic for the CM ref processor, we
4959 // can see some null referent objects.
4960 iter.load_ptrs(DEBUG_ONLY(true));
4961 oop ref = iter.obj();
4962
4963 // This will filter nulls.
4964 if (iter.is_referent_alive()) {
4965 iter.make_referent_alive();
4966 }
4967 iter.move_to_next();
4968 }
4969 }
4970
4971 // Drain the queue - which may cause stealing
4972 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4973 drain_queue.do_void();
4974 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4975 assert(pss->queue_is_empty(), "should be");
4976 }
4977 };
4978
4979 void G1CollectedHeap::process_weak_jni_handles() {
4980 double ref_proc_start = os::elapsedTime();
4981
4982 G1STWIsAliveClosure is_alive(this);
4983 G1KeepAliveClosure keep_alive(this);
4984 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4985
4986 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4987 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4988 }
4989
4990 // Weak Reference processing during an evacuation pause (part 1).
4991 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4992 double ref_proc_start = os::elapsedTime();
4993
4994 ReferenceProcessor* rp = _ref_processor_stw;
4995 assert(rp->discovery_enabled(), "should have been enabled");
4996
4997 // Any reference objects, in the collection set, that were 'discovered'
4998 // by the CM ref processor should have already been copied (either by
4999 // applying the external root copy closure to the discovered lists, or
5000 // by following an RSet entry).
5001 //
5002 // But some of the referents, that are in the collection set, that these
5003 // reference objects point to may not have been copied: the STW ref
5004 // processor would have seen that the reference object had already
5005 // been 'discovered' and would have skipped discovering the reference,
5006 // but would not have treated the reference object as a regular oop.
5007 // As a result the copy closure would not have been applied to the
5008 // referent object.
5009 //
5010 // We need to explicitly copy these referent objects - the references
5011 // will be processed at the end of remarking.
5012 //
5013 // We also need to do this copying before we process the reference
5014 // objects discovered by the STW ref processor in case one of these
5015 // referents points to another object which is also referenced by an
5016 // object discovered by the STW ref processor.
5017
5018 uint no_of_gc_workers = workers()->active_workers();
5019
5020 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5021 per_thread_states,
5022 no_of_gc_workers,
5023 _task_queues);
5024
5025 workers()->run_task(&keep_cm_referents);
5026
5027 // Closure to test whether a referent is alive.
5028 G1STWIsAliveClosure is_alive(this);
5029
5030 // Even when parallel reference processing is enabled, the processing
5031 // of JNI refs is serial and performed serially by the current thread
5032 // rather than by a worker. The following PSS will be used for processing
5033 // JNI refs.
5034
5035 // Use only a single queue for this PSS.
5036 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5037 pss->set_ref_processor(NULL);
5038 assert(pss->queue_is_empty(), "pre-condition");
5039
5040 // Keep alive closure.
5041 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5042
5043 // Serial Complete GC closure
5044 G1STWDrainQueueClosure drain_queue(this, pss);
5045
5046 // Setup the soft refs policy...
5047 rp->setup_policy(false);
5048
5049 ReferenceProcessorStats stats;
5050 if (!rp->processing_is_mt()) {
5051 // Serial reference processing...
5052 stats = rp->process_discovered_references(&is_alive,
5053 &keep_alive,
5054 &drain_queue,
5055 NULL,
5056 _gc_timer_stw);
5057 } else {
5058 // Parallel reference processing
5059 assert(rp->num_q() == no_of_gc_workers, "sanity");
5060 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5061
5062 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5063 stats = rp->process_discovered_references(&is_alive,
5064 &keep_alive,
5065 &drain_queue,
5066 &par_task_executor,
5067 _gc_timer_stw);
5068 }
5069
5070 _gc_tracer_stw->report_gc_reference_stats(stats);
5071
5072 // We have completed copying any necessary live referent objects.
5073 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5074
5075 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5076 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5077 }
5078
5079 // Weak Reference processing during an evacuation pause (part 2).
5080 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5081 double ref_enq_start = os::elapsedTime();
5082
5083 ReferenceProcessor* rp = _ref_processor_stw;
5084 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5085
5086 // Now enqueue any remaining on the discovered lists on to
5087 // the pending list.
5088 if (!rp->processing_is_mt()) {
5089 // Serial reference processing...
5090 rp->enqueue_discovered_references();
5091 } else {
5092 // Parallel reference enqueueing
5093
5094 uint n_workers = workers()->active_workers();
5095
5096 assert(rp->num_q() == n_workers, "sanity");
5097 assert(n_workers <= rp->max_num_q(), "sanity");
5098
5099 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5100 rp->enqueue_discovered_references(&par_task_executor);
5101 }
5102
5103 rp->verify_no_references_recorded();
5104 assert(!rp->discovery_enabled(), "should have been disabled");
5105
5106 // FIXME
5107 // CM's reference processing also cleans up the string and symbol tables.
5108 // Should we do that here also? We could, but it is a serial operation
5109 // and could significantly increase the pause time.
5110
5111 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5112 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5113 }
5114
5115 void G1CollectedHeap::pre_evacuate_collection_set() {
5116 _expand_heap_after_alloc_failure = true;
5117 _evacuation_failed = false;
5118
5119 // Disable the hot card cache.
5120 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5121 hot_card_cache->reset_hot_cache_claimed_index();
5122 hot_card_cache->set_use_cache(false);
5123
5124 }
5125
5126 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5127 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5128
5129 // Should G1EvacuationFailureALot be in effect for this GC?
5130 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5131
5132 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5133 double start_par_time_sec = os::elapsedTime();
5134 double end_par_time_sec;
5135
5136 {
5137 const uint n_workers = workers()->active_workers();
5138 G1RootProcessor root_processor(this, n_workers);
5139 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5140 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5141 if (collector_state()->during_initial_mark_pause()) {
5142 ClassLoaderDataGraph::clear_claimed_marks();
5143 }
5144
5145 // The individual threads will set their evac-failure closures.
5146 if (PrintTerminationStats) {
5147 print_termination_stats_hdr(gclog_or_tty);
5148 }
5149
5150 workers()->run_task(&g1_par_task);
5151 end_par_time_sec = os::elapsedTime();
5152
5153 // Closing the inner scope will execute the destructor
5154 // for the G1RootProcessor object. We record the current
5155 // elapsed time before closing the scope so that time
5156 // taken for the destructor is NOT included in the
5157 // reported parallel time.
5158 }
5159
5160 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5161
5162 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5163 phase_times->record_par_time(par_time_ms);
5164
5165 double code_root_fixup_time_ms =
5166 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5167 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5168
5169 // Process any discovered reference objects - we have
5170 // to do this _before_ we retire the GC alloc regions
5171 // as we may have to copy some 'reachable' referent
5172 // objects (and their reachable sub-graphs) that were
5173 // not copied during the pause.
5174 if (g1_policy()->should_process_references()) {
5175 process_discovered_references(per_thread_states);
5176 } else {
5177 ref_processor_stw()->verify_no_references_recorded();
5178 process_weak_jni_handles();
5179 }
5180
5181 if (G1StringDedup::is_enabled()) {
5182 double fixup_start = os::elapsedTime();
5183
5184 G1STWIsAliveClosure is_alive(this);
5185 G1KeepAliveClosure keep_alive(this);
5186 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5187
5188 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5189 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5190 }
5191
5192 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5193
5194 if (evacuation_failed()) {
5195 restore_after_evac_failure();
5196
5197 // Reset the G1EvacuationFailureALot counters and flags
5198 // Note: the values are reset only when an actual
5199 // evacuation failure occurs.
5200 NOT_PRODUCT(reset_evacuation_should_fail();)
5201 }
5202
5203 // Enqueue any remaining references remaining on the STW
5204 // reference processor's discovered lists. We need to do
5205 // this after the card table is cleaned (and verified) as
5206 // the act of enqueueing entries on to the pending list
5207 // will log these updates (and dirty their associated
5208 // cards). We need these updates logged to update any
5209 // RSets.
5210 if (g1_policy()->should_process_references()) {
5211 enqueue_discovered_references(per_thread_states);
5212 } else {
5213 g1_policy()->phase_times()->record_ref_enq_time(0);
5214 }
5215 }
5216
5217 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5218 _allocator->release_gc_alloc_regions(evacuation_info);
5219
5220 per_thread_states->flush();
5221
5222 record_obj_copy_mem_stats();
5223
5224 _survivor_evac_stats.adjust_desired_plab_sz();
5225 _old_evac_stats.adjust_desired_plab_sz();
5226
5227 // Reset and re-enable the hot card cache.
5228 // Note the counts for the cards in the regions in the
5229 // collection set are reset when the collection set is freed.
5230 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5231 hot_card_cache->reset_hot_cache();
5232 hot_card_cache->set_use_cache(true);
5233
5234 purge_code_root_memory();
5235
5236 redirty_logged_cards();
5237 #if defined(COMPILER2) || INCLUDE_JVMCI
5238 DerivedPointerTable::update_pointers();
5239 #endif
5240 }
5241
5242 void G1CollectedHeap::record_obj_copy_mem_stats() {
5243 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5244
5245 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5246 create_g1_evac_summary(&_old_evac_stats));
5247 }
5248
5249 void G1CollectedHeap::free_region(HeapRegion* hr,
5250 FreeRegionList* free_list,
5251 bool par,
5252 bool locked) {
5253 assert(!hr->is_free(), "the region should not be free");
5254 assert(!hr->is_empty(), "the region should not be empty");
5255 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5256 assert(free_list != NULL, "pre-condition");
5257
5258 if (G1VerifyBitmaps) {
5259 MemRegion mr(hr->bottom(), hr->end());
5260 concurrent_mark()->clearRangePrevBitmap(mr);
5261 }
5262
5263 // Clear the card counts for this region.
5264 // Note: we only need to do this if the region is not young
5265 // (since we don't refine cards in young regions).
5266 if (!hr->is_young()) {
5267 _cg1r->hot_card_cache()->reset_card_counts(hr);
5268 }
5269 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5270 free_list->add_ordered(hr);
5271 }
5272
5273 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5274 FreeRegionList* free_list,
5275 bool par) {
5276 assert(hr->is_humongous(), "this is only for humongous regions");
5277 assert(free_list != NULL, "pre-condition");
5278 hr->clear_humongous();
5279 free_region(hr, free_list, par);
5280 }
5281
5282 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5283 const HeapRegionSetCount& humongous_regions_removed) {
5284 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5285 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5286 _old_set.bulk_remove(old_regions_removed);
5287 _humongous_set.bulk_remove(humongous_regions_removed);
5288 }
5289
5290 }
5291
5292 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5293 assert(list != NULL, "list can't be null");
5294 if (!list->is_empty()) {
5295 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5296 _hrm.insert_list_into_free_list(list);
5297 }
5298 }
5299
5300 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5301 decrease_used(bytes);
5302 }
5303
5304 class G1ParCleanupCTTask : public AbstractGangTask {
5305 G1SATBCardTableModRefBS* _ct_bs;
5306 G1CollectedHeap* _g1h;
5307 HeapRegion* volatile _su_head;
5308 public:
5309 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5310 G1CollectedHeap* g1h) :
5311 AbstractGangTask("G1 Par Cleanup CT Task"),
5312 _ct_bs(ct_bs), _g1h(g1h) { }
5313
5314 void work(uint worker_id) {
5315 HeapRegion* r;
5316 while (r = _g1h->pop_dirty_cards_region()) {
5317 clear_cards(r);
5318 }
5319 }
5320
5321 void clear_cards(HeapRegion* r) {
5322 // Cards of the survivors should have already been dirtied.
5323 if (!r->is_survivor()) {
5324 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5325 }
5326 }
5327 };
5328
5329 #ifndef PRODUCT
5330 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5331 G1CollectedHeap* _g1h;
5332 G1SATBCardTableModRefBS* _ct_bs;
5333 public:
5334 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5335 : _g1h(g1h), _ct_bs(ct_bs) { }
5336 virtual bool doHeapRegion(HeapRegion* r) {
5337 if (r->is_survivor()) {
5338 _g1h->verify_dirty_region(r);
5339 } else {
5340 _g1h->verify_not_dirty_region(r);
5341 }
5342 return false;
5343 }
5344 };
5345
5346 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5347 // All of the region should be clean.
5348 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5349 MemRegion mr(hr->bottom(), hr->end());
5350 ct_bs->verify_not_dirty_region(mr);
5351 }
5352
5353 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5354 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5355 // dirty allocated blocks as they allocate them. The thread that
5356 // retires each region and replaces it with a new one will do a
5357 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5358 // not dirty that area (one less thing to have to do while holding
5359 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5360 // is dirty.
5361 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5362 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5363 if (hr->is_young()) {
5364 ct_bs->verify_g1_young_region(mr);
5365 } else {
5366 ct_bs->verify_dirty_region(mr);
5367 }
5368 }
5369
5370 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5371 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5372 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5373 verify_dirty_region(hr);
5374 }
5375 }
5376
5377 void G1CollectedHeap::verify_dirty_young_regions() {
5378 verify_dirty_young_list(_young_list->first_region());
5379 }
5380
5381 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5382 HeapWord* tams, HeapWord* end) {
5383 guarantee(tams <= end,
5384 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5385 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5386 if (result < end) {
5387 gclog_or_tty->cr();
5388 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5389 bitmap_name, p2i(result));
5390 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5391 bitmap_name, p2i(tams), p2i(end));
5392 return false;
5393 }
5394 return true;
5395 }
5396
5397 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5398 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5399 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5400
5401 HeapWord* bottom = hr->bottom();
5402 HeapWord* ptams = hr->prev_top_at_mark_start();
5403 HeapWord* ntams = hr->next_top_at_mark_start();
5404 HeapWord* end = hr->end();
5405
5406 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5407
5408 bool res_n = true;
5409 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5410 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5411 // if we happen to be in that state.
5412 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5413 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5414 }
5415 if (!res_p || !res_n) {
5416 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5417 HR_FORMAT_PARAMS(hr));
5418 gclog_or_tty->print_cr("#### Caller: %s", caller);
5419 return false;
5420 }
5421 return true;
5422 }
5423
5424 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5425 if (!G1VerifyBitmaps) return;
5426
5427 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5428 }
5429
5430 class G1VerifyBitmapClosure : public HeapRegionClosure {
5431 private:
5432 const char* _caller;
5433 G1CollectedHeap* _g1h;
5434 bool _failures;
5435
5436 public:
5437 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5438 _caller(caller), _g1h(g1h), _failures(false) { }
5439
5440 bool failures() { return _failures; }
5441
5442 virtual bool doHeapRegion(HeapRegion* hr) {
5443 bool result = _g1h->verify_bitmaps(_caller, hr);
5444 if (!result) {
5445 _failures = true;
5446 }
5447 return false;
5448 }
5449 };
5450
5451 void G1CollectedHeap::check_bitmaps(const char* caller) {
5452 if (!G1VerifyBitmaps) return;
5453
5454 G1VerifyBitmapClosure cl(caller, this);
5455 heap_region_iterate(&cl);
5456 guarantee(!cl.failures(), "bitmap verification");
5457 }
5458
5459 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5460 private:
5461 bool _failures;
5462 public:
5463 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5464
5465 virtual bool doHeapRegion(HeapRegion* hr) {
5466 uint i = hr->hrm_index();
5467 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5468 if (hr->is_humongous()) {
5469 if (hr->in_collection_set()) {
5470 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5471 _failures = true;
5472 return true;
5473 }
5474 if (cset_state.is_in_cset()) {
5475 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5476 _failures = true;
5477 return true;
5478 }
5479 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5480 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5481 _failures = true;
5482 return true;
5483 }
5484 } else {
5485 if (cset_state.is_humongous()) {
5486 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5487 _failures = true;
5488 return true;
5489 }
5490 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5491 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5492 hr->in_collection_set(), cset_state.value(), i);
5493 _failures = true;
5494 return true;
5495 }
5496 if (cset_state.is_in_cset()) {
5497 if (hr->is_young() != (cset_state.is_young())) {
5498 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5499 hr->is_young(), cset_state.value(), i);
5500 _failures = true;
5501 return true;
5502 }
5503 if (hr->is_old() != (cset_state.is_old())) {
5504 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5505 hr->is_old(), cset_state.value(), i);
5506 _failures = true;
5507 return true;
5508 }
5509 }
5510 }
5511 return false;
5512 }
5513
5514 bool failures() const { return _failures; }
5515 };
5516
5517 bool G1CollectedHeap::check_cset_fast_test() {
5518 G1CheckCSetFastTableClosure cl;
5519 _hrm.iterate(&cl);
5520 return !cl.failures();
5521 }
5522 #endif // PRODUCT
5523
5524 void G1CollectedHeap::cleanUpCardTable() {
5525 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5526 double start = os::elapsedTime();
5527
5528 {
5529 // Iterate over the dirty cards region list.
5530 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5531
5532 workers()->run_task(&cleanup_task);
5533 #ifndef PRODUCT
5534 if (G1VerifyCTCleanup || VerifyAfterGC) {
5535 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5536 heap_region_iterate(&cleanup_verifier);
5537 }
5538 #endif
5539 }
5540
5541 double elapsed = os::elapsedTime() - start;
5542 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5543 }
5544
5545 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5546 size_t pre_used = 0;
5547 FreeRegionList local_free_list("Local List for CSet Freeing");
5548
5549 double young_time_ms = 0.0;
5550 double non_young_time_ms = 0.0;
5551
5552 // Since the collection set is a superset of the the young list,
5553 // all we need to do to clear the young list is clear its
5554 // head and length, and unlink any young regions in the code below
5555 _young_list->clear();
5556
5557 G1CollectorPolicy* policy = g1_policy();
5558
5559 double start_sec = os::elapsedTime();
5560 bool non_young = true;
5561
5562 HeapRegion* cur = cs_head;
5563 int age_bound = -1;
5564 size_t rs_lengths = 0;
5565
5566 while (cur != NULL) {
5567 assert(!is_on_master_free_list(cur), "sanity");
5568 if (non_young) {
5569 if (cur->is_young()) {
5570 double end_sec = os::elapsedTime();
5571 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5572 non_young_time_ms += elapsed_ms;
5573
5574 start_sec = os::elapsedTime();
5575 non_young = false;
5576 }
5577 } else {
5578 if (!cur->is_young()) {
5579 double end_sec = os::elapsedTime();
5580 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5581 young_time_ms += elapsed_ms;
5582
5583 start_sec = os::elapsedTime();
5584 non_young = true;
5585 }
5586 }
5587
5588 rs_lengths += cur->rem_set()->occupied_locked();
5589
5590 HeapRegion* next = cur->next_in_collection_set();
5591 assert(cur->in_collection_set(), "bad CS");
5592 cur->set_next_in_collection_set(NULL);
5593 clear_in_cset(cur);
5594
5595 if (cur->is_young()) {
5596 int index = cur->young_index_in_cset();
5597 assert(index != -1, "invariant");
5598 assert((uint) index < policy->young_cset_region_length(), "invariant");
5599 size_t words_survived = surviving_young_words[index];
5600 cur->record_surv_words_in_group(words_survived);
5601
5602 // At this point the we have 'popped' cur from the collection set
5603 // (linked via next_in_collection_set()) but it is still in the
5604 // young list (linked via next_young_region()). Clear the
5605 // _next_young_region field.
5606 cur->set_next_young_region(NULL);
5607 } else {
5608 int index = cur->young_index_in_cset();
5609 assert(index == -1, "invariant");
5610 }
5611
5612 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5613 (!cur->is_young() && cur->young_index_in_cset() == -1),
5614 "invariant" );
5615
5616 if (!cur->evacuation_failed()) {
5617 MemRegion used_mr = cur->used_region();
5618
5619 // And the region is empty.
5620 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5621 pre_used += cur->used();
5622 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5623 } else {
5624 cur->uninstall_surv_rate_group();
5625 if (cur->is_young()) {
5626 cur->set_young_index_in_cset(-1);
5627 }
5628 cur->set_evacuation_failed(false);
5629 // When moving a young gen region to old gen, we "allocate" that whole region
5630 // there. This is in addition to any already evacuated objects. Notify the
5631 // policy about that.
5632 // Old gen regions do not cause an additional allocation: both the objects
5633 // still in the region and the ones already moved are accounted for elsewhere.
5634 if (cur->is_young()) {
5635 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5636 }
5637 // The region is now considered to be old.
5638 cur->set_old();
5639 // Do some allocation statistics accounting. Regions that failed evacuation
5640 // are always made old, so there is no need to update anything in the young
5641 // gen statistics, but we need to update old gen statistics.
5642 size_t used_words = cur->marked_bytes() / HeapWordSize;
5643 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5644 _old_set.add(cur);
5645 evacuation_info.increment_collectionset_used_after(cur->used());
5646 }
5647 cur = next;
5648 }
5649
5650 evacuation_info.set_regions_freed(local_free_list.length());
5651 policy->record_max_rs_lengths(rs_lengths);
5652 policy->cset_regions_freed();
5653
5654 double end_sec = os::elapsedTime();
5655 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5656
5657 if (non_young) {
5658 non_young_time_ms += elapsed_ms;
5659 } else {
5660 young_time_ms += elapsed_ms;
5661 }
5662
5663 prepend_to_freelist(&local_free_list);
5664 decrement_summary_bytes(pre_used);
5665 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5666 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5667 }
5668
5669 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5670 private:
5671 FreeRegionList* _free_region_list;
5672 HeapRegionSet* _proxy_set;
5673 HeapRegionSetCount _humongous_regions_removed;
5674 size_t _freed_bytes;
5675 public:
5676
5677 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5678 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5679 }
5680
5681 virtual bool doHeapRegion(HeapRegion* r) {
5682 if (!r->is_starts_humongous()) {
5683 return false;
5684 }
5685
5686 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5687
5688 oop obj = (oop)r->bottom();
5689 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5690
5691 // The following checks whether the humongous object is live are sufficient.
5692 // The main additional check (in addition to having a reference from the roots
5693 // or the young gen) is whether the humongous object has a remembered set entry.
5694 //
5695 // A humongous object cannot be live if there is no remembered set for it
5696 // because:
5697 // - there can be no references from within humongous starts regions referencing
5698 // the object because we never allocate other objects into them.
5699 // (I.e. there are no intra-region references that may be missed by the
5700 // remembered set)
5701 // - as soon there is a remembered set entry to the humongous starts region
5702 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5703 // until the end of a concurrent mark.
5704 //
5705 // It is not required to check whether the object has been found dead by marking
5706 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5707 // all objects allocated during that time are considered live.
5708 // SATB marking is even more conservative than the remembered set.
5709 // So if at this point in the collection there is no remembered set entry,
5710 // nobody has a reference to it.
5711 // At the start of collection we flush all refinement logs, and remembered sets
5712 // are completely up-to-date wrt to references to the humongous object.
5713 //
5714 // Other implementation considerations:
5715 // - never consider object arrays at this time because they would pose
5716 // considerable effort for cleaning up the the remembered sets. This is
5717 // required because stale remembered sets might reference locations that
5718 // are currently allocated into.
5719 uint region_idx = r->hrm_index();
5720 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5721 !r->rem_set()->is_empty()) {
5722
5723 if (G1TraceEagerReclaimHumongousObjects) {
5724 gclog_or_tty->print_cr("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",
5725 region_idx,
5726 (size_t)obj->size() * HeapWordSize,
5727 p2i(r->bottom()),
5728 r->rem_set()->occupied(),
5729 r->rem_set()->strong_code_roots_list_length(),
5730 next_bitmap->isMarked(r->bottom()),
5731 g1h->is_humongous_reclaim_candidate(region_idx),
5732 obj->is_typeArray()
5733 );
5734 }
5735
5736 return false;
5737 }
5738
5739 guarantee(obj->is_typeArray(),
5740 "Only eagerly reclaiming type arrays is supported, but the object "
5741 PTR_FORMAT " is not.", p2i(r->bottom()));
5742
5743 if (G1TraceEagerReclaimHumongousObjects) {
5744 gclog_or_tty->print_cr("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",
5745 region_idx,
5746 (size_t)obj->size() * HeapWordSize,
5747 p2i(r->bottom()),
5748 r->rem_set()->occupied(),
5749 r->rem_set()->strong_code_roots_list_length(),
5750 next_bitmap->isMarked(r->bottom()),
5751 g1h->is_humongous_reclaim_candidate(region_idx),
5752 obj->is_typeArray()
5753 );
5754 }
5755 // Need to clear mark bit of the humongous object if already set.
5756 if (next_bitmap->isMarked(r->bottom())) {
5757 next_bitmap->clear(r->bottom());
5758 }
5759 do {
5760 HeapRegion* next = g1h->next_region_in_humongous(r);
5761 _freed_bytes += r->used();
5762 r->set_containing_set(NULL);
5763 _humongous_regions_removed.increment(1u, r->capacity());
5764 g1h->free_humongous_region(r, _free_region_list, false);
5765 r = next;
5766 } while (r != NULL);
5767
5768 return false;
5769 }
5770
5771 HeapRegionSetCount& humongous_free_count() {
5772 return _humongous_regions_removed;
5773 }
5774
5775 size_t bytes_freed() const {
5776 return _freed_bytes;
5777 }
5778
5779 size_t humongous_reclaimed() const {
5780 return _humongous_regions_removed.length();
5781 }
5782 };
5783
5784 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5785 assert_at_safepoint(true);
5786
5787 if (!G1EagerReclaimHumongousObjects ||
5788 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5789 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5790 return;
5791 }
5792
5793 double start_time = os::elapsedTime();
5794
5795 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5796
5797 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5798 heap_region_iterate(&cl);
5799
5800 HeapRegionSetCount empty_set;
5801 remove_from_old_sets(empty_set, cl.humongous_free_count());
5802
5803 G1HRPrinter* hrp = hr_printer();
5804 if (hrp->is_active()) {
5805 FreeRegionListIterator iter(&local_cleanup_list);
5806 while (iter.more_available()) {
5807 HeapRegion* hr = iter.get_next();
5808 hrp->cleanup(hr);
5809 }
5810 }
5811
5812 prepend_to_freelist(&local_cleanup_list);
5813 decrement_summary_bytes(cl.bytes_freed());
5814
5815 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5816 cl.humongous_reclaimed());
5817 }
5818
5819 // This routine is similar to the above but does not record
5820 // any policy statistics or update free lists; we are abandoning
5821 // the current incremental collection set in preparation of a
5822 // full collection. After the full GC we will start to build up
5823 // the incremental collection set again.
5824 // This is only called when we're doing a full collection
5825 // and is immediately followed by the tearing down of the young list.
5826
5827 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5828 HeapRegion* cur = cs_head;
5829
5830 while (cur != NULL) {
5831 HeapRegion* next = cur->next_in_collection_set();
5832 assert(cur->in_collection_set(), "bad CS");
5833 cur->set_next_in_collection_set(NULL);
5834 clear_in_cset(cur);
5835 cur->set_young_index_in_cset(-1);
5836 cur = next;
5837 }
5838 }
5839
5840 void G1CollectedHeap::set_free_regions_coming() {
5841 if (G1ConcRegionFreeingVerbose) {
5842 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5843 "setting free regions coming");
5844 }
5845
5846 assert(!free_regions_coming(), "pre-condition");
5847 _free_regions_coming = true;
5848 }
5849
5850 void G1CollectedHeap::reset_free_regions_coming() {
5851 assert(free_regions_coming(), "pre-condition");
5852
5853 {
5854 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5855 _free_regions_coming = false;
5856 SecondaryFreeList_lock->notify_all();
5857 }
5858
5859 if (G1ConcRegionFreeingVerbose) {
5860 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5861 "reset free regions coming");
5862 }
5863 }
5864
5865 void G1CollectedHeap::wait_while_free_regions_coming() {
5866 // Most of the time we won't have to wait, so let's do a quick test
5867 // first before we take the lock.
5868 if (!free_regions_coming()) {
5869 return;
5870 }
5871
5872 if (G1ConcRegionFreeingVerbose) {
5873 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5874 "waiting for free regions");
5875 }
5876
5877 {
5878 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5879 while (free_regions_coming()) {
5880 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5881 }
5882 }
5883
5884 if (G1ConcRegionFreeingVerbose) {
5885 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5886 "done waiting for free regions");
5887 }
5888 }
5889
5890 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5891 return _allocator->is_retained_old_region(hr);
5892 }
5893
5894 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5895 _young_list->push_region(hr);
5896 }
5897
5898 class NoYoungRegionsClosure: public HeapRegionClosure {
5899 private:
5900 bool _success;
5901 public:
5902 NoYoungRegionsClosure() : _success(true) { }
5903 bool doHeapRegion(HeapRegion* r) {
5904 if (r->is_young()) {
5905 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5906 p2i(r->bottom()), p2i(r->end()));
5907 _success = false;
5908 }
5909 return false;
5910 }
5911 bool success() { return _success; }
5912 };
5913
5914 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5915 bool ret = _young_list->check_list_empty(check_sample);
5916
5917 if (check_heap) {
5918 NoYoungRegionsClosure closure;
5919 heap_region_iterate(&closure);
5920 ret = ret && closure.success();
5921 }
5922
5923 return ret;
5924 }
5925
5926 class TearDownRegionSetsClosure : public HeapRegionClosure {
5927 private:
5928 HeapRegionSet *_old_set;
5929
5930 public:
5931 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5932
5933 bool doHeapRegion(HeapRegion* r) {
5934 if (r->is_old()) {
5935 _old_set->remove(r);
5936 } else {
5937 // We ignore free regions, we'll empty the free list afterwards.
5938 // We ignore young regions, we'll empty the young list afterwards.
5939 // We ignore humongous regions, we're not tearing down the
5940 // humongous regions set.
5941 assert(r->is_free() || r->is_young() || r->is_humongous(),
5942 "it cannot be another type");
5943 }
5944 return false;
5945 }
5946
5947 ~TearDownRegionSetsClosure() {
5948 assert(_old_set->is_empty(), "post-condition");
5949 }
5950 };
5951
5952 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5953 assert_at_safepoint(true /* should_be_vm_thread */);
5954
5955 if (!free_list_only) {
5956 TearDownRegionSetsClosure cl(&_old_set);
5957 heap_region_iterate(&cl);
5958
5959 // Note that emptying the _young_list is postponed and instead done as
5960 // the first step when rebuilding the regions sets again. The reason for
5961 // this is that during a full GC string deduplication needs to know if
5962 // a collected region was young or old when the full GC was initiated.
5963 }
5964 _hrm.remove_all_free_regions();
5965 }
5966
5967 void G1CollectedHeap::increase_used(size_t bytes) {
5968 _summary_bytes_used += bytes;
5969 }
5970
5971 void G1CollectedHeap::decrease_used(size_t bytes) {
5972 assert(_summary_bytes_used >= bytes,
5973 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5974 _summary_bytes_used, bytes);
5975 _summary_bytes_used -= bytes;
5976 }
5977
5978 void G1CollectedHeap::set_used(size_t bytes) {
5979 _summary_bytes_used = bytes;
5980 }
5981
5982 class RebuildRegionSetsClosure : public HeapRegionClosure {
5983 private:
5984 bool _free_list_only;
5985 HeapRegionSet* _old_set;
5986 HeapRegionManager* _hrm;
5987 size_t _total_used;
5988
5989 public:
5990 RebuildRegionSetsClosure(bool free_list_only,
5991 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5992 _free_list_only(free_list_only),
5993 _old_set(old_set), _hrm(hrm), _total_used(0) {
5994 assert(_hrm->num_free_regions() == 0, "pre-condition");
5995 if (!free_list_only) {
5996 assert(_old_set->is_empty(), "pre-condition");
5997 }
5998 }
5999
6000 bool doHeapRegion(HeapRegion* r) {
6001 if (r->is_empty()) {
6002 // Add free regions to the free list
6003 r->set_free();
6004 r->set_allocation_context(AllocationContext::system());
6005 _hrm->insert_into_free_list(r);
6006 } else if (!_free_list_only) {
6007 assert(!r->is_young(), "we should not come across young regions");
6008
6009 if (r->is_humongous()) {
6010 // We ignore humongous regions. We left the humongous set unchanged.
6011 } else {
6012 // Objects that were compacted would have ended up on regions
6013 // that were previously old or free. Archive regions (which are
6014 // old) will not have been touched.
6015 assert(r->is_free() || r->is_old(), "invariant");
6016 // We now consider them old, so register as such. Leave
6017 // archive regions set that way, however, while still adding
6018 // them to the old set.
6019 if (!r->is_archive()) {
6020 r->set_old();
6021 }
6022 _old_set->add(r);
6023 }
6024 _total_used += r->used();
6025 }
6026
6027 return false;
6028 }
6029
6030 size_t total_used() {
6031 return _total_used;
6032 }
6033 };
6034
6035 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6036 assert_at_safepoint(true /* should_be_vm_thread */);
6037
6038 if (!free_list_only) {
6039 _young_list->empty_list();
6040 }
6041
6042 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6043 heap_region_iterate(&cl);
6044
6045 if (!free_list_only) {
6046 set_used(cl.total_used());
6047 if (_archive_allocator != NULL) {
6048 _archive_allocator->clear_used();
6049 }
6050 }
6051 assert(used_unlocked() == recalculate_used(),
6052 "inconsistent used_unlocked(), "
6053 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6054 used_unlocked(), recalculate_used());
6055 }
6056
6057 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6058 _refine_cte_cl->set_concurrent(concurrent);
6059 }
6060
6061 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6062 HeapRegion* hr = heap_region_containing(p);
6063 return hr->is_in(p);
6064 }
6065
6066 // Methods for the mutator alloc region
6067
6068 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6069 bool force) {
6070 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6071 assert(!force || g1_policy()->can_expand_young_list(),
6072 "if force is true we should be able to expand the young list");
6073 bool young_list_full = g1_policy()->is_young_list_full();
6074 if (force || !young_list_full) {
6075 HeapRegion* new_alloc_region = new_region(word_size,
6076 false /* is_old */,
6077 false /* do_expand */);
6078 if (new_alloc_region != NULL) {
6079 set_region_short_lived_locked(new_alloc_region);
6080 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6081 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6082 return new_alloc_region;
6083 }
6084 }
6085 return NULL;
6086 }
6087
6088 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6089 size_t allocated_bytes) {
6090 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6091 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6092
6093 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6094 increase_used(allocated_bytes);
6095 _hr_printer.retire(alloc_region);
6096 // We update the eden sizes here, when the region is retired,
6097 // instead of when it's allocated, since this is the point that its
6098 // used space has been recored in _summary_bytes_used.
6099 g1mm()->update_eden_size();
6100 }
6101
6102 // Methods for the GC alloc regions
6103
6104 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6105 uint count,
6106 InCSetState dest) {
6107 assert(FreeList_lock->owned_by_self(), "pre-condition");
6108
6109 if (count < g1_policy()->max_regions(dest)) {
6110 const bool is_survivor = (dest.is_young());
6111 HeapRegion* new_alloc_region = new_region(word_size,
6112 !is_survivor,
6113 true /* do_expand */);
6114 if (new_alloc_region != NULL) {
6115 // We really only need to do this for old regions given that we
6116 // should never scan survivors. But it doesn't hurt to do it
6117 // for survivors too.
6118 new_alloc_region->record_timestamp();
6119 if (is_survivor) {
6120 new_alloc_region->set_survivor();
6121 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6122 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6123 } else {
6124 new_alloc_region->set_old();
6125 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6126 check_bitmaps("Old Region Allocation", new_alloc_region);
6127 }
6128 bool during_im = collector_state()->during_initial_mark_pause();
6129 new_alloc_region->note_start_of_copying(during_im);
6130 return new_alloc_region;
6131 }
6132 }
6133 return NULL;
6134 }
6135
6136 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6137 size_t allocated_bytes,
6138 InCSetState dest) {
6139 bool during_im = collector_state()->during_initial_mark_pause();
6140 alloc_region->note_end_of_copying(during_im);
6141 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6142 if (dest.is_young()) {
6143 young_list()->add_survivor_region(alloc_region);
6144 } else {
6145 _old_set.add(alloc_region);
6146 }
6147 _hr_printer.retire(alloc_region);
6148 }
6149
6150 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6151 bool expanded = false;
6152 uint index = _hrm.find_highest_free(&expanded);
6153
6154 if (index != G1_NO_HRM_INDEX) {
6155 if (expanded) {
6156 ergo_verbose1(ErgoHeapSizing,
6157 "attempt heap expansion",
6158 ergo_format_reason("requested address range outside heap bounds")
6159 ergo_format_byte("region size"),
6160 HeapRegion::GrainWords * HeapWordSize);
6161 }
6162 _hrm.allocate_free_regions_starting_at(index, 1);
6163 return region_at(index);
6164 }
6165 return NULL;
6166 }
6167
6168 // Heap region set verification
6169
6170 class VerifyRegionListsClosure : public HeapRegionClosure {
6171 private:
6172 HeapRegionSet* _old_set;
6173 HeapRegionSet* _humongous_set;
6174 HeapRegionManager* _hrm;
6175
6176 public:
6177 HeapRegionSetCount _old_count;
6178 HeapRegionSetCount _humongous_count;
6179 HeapRegionSetCount _free_count;
6180
6181 VerifyRegionListsClosure(HeapRegionSet* old_set,
6182 HeapRegionSet* humongous_set,
6183 HeapRegionManager* hrm) :
6184 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6185 _old_count(), _humongous_count(), _free_count(){ }
6186
6187 bool doHeapRegion(HeapRegion* hr) {
6188 if (hr->is_young()) {
6189 // TODO
6190 } else if (hr->is_humongous()) {
6191 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6192 _humongous_count.increment(1u, hr->capacity());
6193 } else if (hr->is_empty()) {
6194 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6195 _free_count.increment(1u, hr->capacity());
6196 } else if (hr->is_old()) {
6197 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6198 _old_count.increment(1u, hr->capacity());
6199 } else {
6200 // There are no other valid region types. Check for one invalid
6201 // one we can identify: pinned without old or humongous set.
6202 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6203 ShouldNotReachHere();
6204 }
6205 return false;
6206 }
6207
6208 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6209 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6210 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6211 old_set->total_capacity_bytes(), _old_count.capacity());
6212
6213 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6214 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6215 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6216
6217 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6218 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6219 free_list->total_capacity_bytes(), _free_count.capacity());
6220 }
6221 };
6222
6223 void G1CollectedHeap::verify_region_sets() {
6224 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6225
6226 // First, check the explicit lists.
6227 _hrm.verify();
6228 {
6229 // Given that a concurrent operation might be adding regions to
6230 // the secondary free list we have to take the lock before
6231 // verifying it.
6232 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6233 _secondary_free_list.verify_list();
6234 }
6235
6236 // If a concurrent region freeing operation is in progress it will
6237 // be difficult to correctly attributed any free regions we come
6238 // across to the correct free list given that they might belong to
6239 // one of several (free_list, secondary_free_list, any local lists,
6240 // etc.). So, if that's the case we will skip the rest of the
6241 // verification operation. Alternatively, waiting for the concurrent
6242 // operation to complete will have a non-trivial effect on the GC's
6243 // operation (no concurrent operation will last longer than the
6244 // interval between two calls to verification) and it might hide
6245 // any issues that we would like to catch during testing.
6246 if (free_regions_coming()) {
6247 return;
6248 }
6249
6250 // Make sure we append the secondary_free_list on the free_list so
6251 // that all free regions we will come across can be safely
6252 // attributed to the free_list.
6253 append_secondary_free_list_if_not_empty_with_lock();
6254
6255 // Finally, make sure that the region accounting in the lists is
6256 // consistent with what we see in the heap.
6257
6258 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6259 heap_region_iterate(&cl);
6260 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6261 }
6262
6263 // Optimized nmethod scanning
6264
6265 class RegisterNMethodOopClosure: public OopClosure {
6266 G1CollectedHeap* _g1h;
6267 nmethod* _nm;
6268
6269 template <class T> void do_oop_work(T* p) {
6270 T heap_oop = oopDesc::load_heap_oop(p);
6271 if (!oopDesc::is_null(heap_oop)) {
6272 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6273 HeapRegion* hr = _g1h->heap_region_containing(obj);
6274 assert(!hr->is_continues_humongous(),
6275 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6276 " starting at " HR_FORMAT,
6277 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6278
6279 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6280 hr->add_strong_code_root_locked(_nm);
6281 }
6282 }
6283
6284 public:
6285 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6286 _g1h(g1h), _nm(nm) {}
6287
6288 void do_oop(oop* p) { do_oop_work(p); }
6289 void do_oop(narrowOop* p) { do_oop_work(p); }
6290 };
6291
6292 class UnregisterNMethodOopClosure: public OopClosure {
6293 G1CollectedHeap* _g1h;
6294 nmethod* _nm;
6295
6296 template <class T> void do_oop_work(T* p) {
6297 T heap_oop = oopDesc::load_heap_oop(p);
6298 if (!oopDesc::is_null(heap_oop)) {
6299 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6300 HeapRegion* hr = _g1h->heap_region_containing(obj);
6301 assert(!hr->is_continues_humongous(),
6302 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6303 " starting at " HR_FORMAT,
6304 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6305
6306 hr->remove_strong_code_root(_nm);
6307 }
6308 }
6309
6310 public:
6311 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6312 _g1h(g1h), _nm(nm) {}
6313
6314 void do_oop(oop* p) { do_oop_work(p); }
6315 void do_oop(narrowOop* p) { do_oop_work(p); }
6316 };
6317
6318 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6319 CollectedHeap::register_nmethod(nm);
6320
6321 guarantee(nm != NULL, "sanity");
6322 RegisterNMethodOopClosure reg_cl(this, nm);
6323 nm->oops_do(®_cl);
6324 }
6325
6326 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6327 CollectedHeap::unregister_nmethod(nm);
6328
6329 guarantee(nm != NULL, "sanity");
6330 UnregisterNMethodOopClosure reg_cl(this, nm);
6331 nm->oops_do(®_cl, true);
6332 }
6333
6334 void G1CollectedHeap::purge_code_root_memory() {
6335 double purge_start = os::elapsedTime();
6336 G1CodeRootSet::purge();
6337 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6338 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6339 }
6340
6341 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6342 G1CollectedHeap* _g1h;
6343
6344 public:
6345 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6346 _g1h(g1h) {}
6347
6348 void do_code_blob(CodeBlob* cb) {
6349 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6350 if (nm == NULL) {
6351 return;
6352 }
6353
6354 if (ScavengeRootsInCode) {
6355 _g1h->register_nmethod(nm);
6356 }
6357 }
6358 };
6359
6360 void G1CollectedHeap::rebuild_strong_code_roots() {
6361 RebuildStrongCodeRootClosure blob_cl(this);
6362 CodeCache::blobs_do(&blob_cl);
6363 }