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/g1EvacFailure.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 + 1.
304 uint last = first + num_regions;
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 // We will set up the first region as "starts humongous". This
342 // will also update the BOT covering all the regions to reflect
343 // that there is a single object that starts at the bottom of the
344 // first region.
345 first_hr->set_starts_humongous(obj_top);
346 first_hr->set_allocation_context(context);
347 // Then, if there are any, we will set up the "continues
348 // humongous" regions.
349 HeapRegion* hr = NULL;
350 for (uint i = first + 1; i < last; ++i) {
351 hr = region_at(i);
352 hr->set_continues_humongous(first_hr);
353 hr->set_allocation_context(context);
354 }
355
356 // Up to this point no concurrent thread would have been able to
357 // do any scanning on any region in this series. All the top
358 // fields still point to bottom, so the intersection between
359 // [bottom,top] and [card_start,card_end] will be empty. Before we
360 // update the top fields, we'll do a storestore to make sure that
361 // no thread sees the update to top before the zeroing of the
362 // object header and the BOT initialization.
363 OrderAccess::storestore();
364
365 // Now that the BOT and the object header have been initialized,
366 // we can update top of the "starts humongous" region.
367 first_hr->set_top(MIN2(first_hr->end(), obj_top));
368 if (_hr_printer.is_active()) {
369 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
370 }
371
372 // Now, we will update the top fields of the "continues humongous"
373 // regions.
374 hr = NULL;
375 for (uint i = first + 1; i < last; ++i) {
376 hr = region_at(i);
377 if ((i + 1) == last) {
378 // last continues humongous region
379 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
380 "new_top should fall on this region");
381 hr->set_top(obj_top);
382 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
383 } else {
384 // not last one
385 assert(obj_top > hr->end(), "obj_top should be above this region");
386 hr->set_top(hr->end());
387 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
388 }
389 }
390 // If we have continues humongous regions (hr != NULL), its top should
391 // match obj_top.
392 assert(hr == NULL || (hr->top() == obj_top), "sanity");
393 check_bitmaps("Humongous Region Allocation", first_hr);
394
395 increase_used(word_size * HeapWordSize);
396
397 for (uint i = first; i < last; ++i) {
398 _humongous_set.add(region_at(i));
399 }
400
401 return new_obj;
402 }
403
404 // If could fit into free regions w/o expansion, try.
405 // Otherwise, if can expand, do so.
406 // Otherwise, if using ex regions might help, try with ex given back.
407 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
408 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
409
410 verify_region_sets_optional();
411
412 uint first = G1_NO_HRM_INDEX;
413 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
414
415 if (obj_regions == 1) {
416 // Only one region to allocate, try to use a fast path by directly allocating
417 // from the free lists. Do not try to expand here, we will potentially do that
418 // later.
419 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
420 if (hr != NULL) {
421 first = hr->hrm_index();
422 }
423 } else {
424 // We can't allocate humongous regions spanning more than one region while
425 // cleanupComplete() is running, since some of the regions we find to be
426 // empty might not yet be added to the free list. It is not straightforward
427 // to know in which list they are on so that we can remove them. We only
428 // need to do this if we need to allocate more than one region to satisfy the
429 // current humongous allocation request. If we are only allocating one region
430 // we use the one-region region allocation code (see above), that already
431 // potentially waits for regions from the secondary free list.
432 wait_while_free_regions_coming();
433 append_secondary_free_list_if_not_empty_with_lock();
434
435 // Policy: Try only empty regions (i.e. already committed first). Maybe we
436 // are lucky enough to find some.
437 first = _hrm.find_contiguous_only_empty(obj_regions);
438 if (first != G1_NO_HRM_INDEX) {
439 _hrm.allocate_free_regions_starting_at(first, obj_regions);
440 }
441 }
442
443 if (first == G1_NO_HRM_INDEX) {
444 // Policy: We could not find enough regions for the humongous object in the
445 // free list. Look through the heap to find a mix of free and uncommitted regions.
446 // If so, try expansion.
447 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
448 if (first != G1_NO_HRM_INDEX) {
449 // We found something. Make sure these regions are committed, i.e. expand
450 // the heap. Alternatively we could do a defragmentation GC.
451 ergo_verbose1(ErgoHeapSizing,
452 "attempt heap expansion",
453 ergo_format_reason("humongous allocation request failed")
454 ergo_format_byte("allocation request"),
455 word_size * HeapWordSize);
456
457 _hrm.expand_at(first, obj_regions);
458 g1_policy()->record_new_heap_size(num_regions());
459
460 #ifdef ASSERT
461 for (uint i = first; i < first + obj_regions; ++i) {
462 HeapRegion* hr = region_at(i);
463 assert(hr->is_free(), "sanity");
464 assert(hr->is_empty(), "sanity");
465 assert(is_on_master_free_list(hr), "sanity");
466 }
467 #endif
468 _hrm.allocate_free_regions_starting_at(first, obj_regions);
469 } else {
470 // Policy: Potentially trigger a defragmentation GC.
471 }
472 }
473
474 HeapWord* result = NULL;
475 if (first != G1_NO_HRM_INDEX) {
476 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
477 word_size, context);
478 assert(result != NULL, "it should always return a valid result");
479
480 // A successful humongous object allocation changes the used space
481 // information of the old generation so we need to recalculate the
482 // sizes and update the jstat counters here.
483 g1mm()->update_sizes();
484 }
485
486 verify_region_sets_optional();
487
488 return result;
489 }
490
491 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
492 assert_heap_not_locked_and_not_at_safepoint();
493 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
494
495 uint dummy_gc_count_before;
496 uint dummy_gclocker_retry_count = 0;
497 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
498 }
499
500 HeapWord*
501 G1CollectedHeap::mem_allocate(size_t word_size,
502 bool* gc_overhead_limit_was_exceeded) {
503 assert_heap_not_locked_and_not_at_safepoint();
504
505 // Loop until the allocation is satisfied, or unsatisfied after GC.
506 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
507 uint gc_count_before;
508
509 HeapWord* result = NULL;
510 if (!is_humongous(word_size)) {
511 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
512 } else {
513 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
514 }
515 if (result != NULL) {
516 return result;
517 }
518
519 // Create the garbage collection operation...
520 VM_G1CollectForAllocation op(gc_count_before, word_size);
521 op.set_allocation_context(AllocationContext::current());
522
523 // ...and get the VM thread to execute it.
524 VMThread::execute(&op);
525
526 if (op.prologue_succeeded() && op.pause_succeeded()) {
527 // If the operation was successful we'll return the result even
528 // if it is NULL. If the allocation attempt failed immediately
529 // after a Full GC, it's unlikely we'll be able to allocate now.
530 HeapWord* result = op.result();
531 if (result != NULL && !is_humongous(word_size)) {
532 // Allocations that take place on VM operations do not do any
533 // card dirtying and we have to do it here. We only have to do
534 // this for non-humongous allocations, though.
535 dirty_young_block(result, word_size);
536 }
537 return result;
538 } else {
539 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
540 return NULL;
541 }
542 assert(op.result() == NULL,
543 "the result should be NULL if the VM op did not succeed");
544 }
545
546 // Give a warning if we seem to be looping forever.
547 if ((QueuedAllocationWarningCount > 0) &&
548 (try_count % QueuedAllocationWarningCount == 0)) {
549 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
550 }
551 }
552
553 ShouldNotReachHere();
554 return NULL;
555 }
556
557 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
558 AllocationContext_t context,
559 uint* gc_count_before_ret,
560 uint* gclocker_retry_count_ret) {
561 // Make sure you read the note in attempt_allocation_humongous().
562
563 assert_heap_not_locked_and_not_at_safepoint();
564 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
565 "be called for humongous allocation requests");
566
567 // We should only get here after the first-level allocation attempt
568 // (attempt_allocation()) failed to allocate.
569
570 // We will loop until a) we manage to successfully perform the
571 // allocation or b) we successfully schedule a collection which
572 // fails to perform the allocation. b) is the only case when we'll
573 // return NULL.
574 HeapWord* result = NULL;
575 for (int try_count = 1; /* we'll return */; try_count += 1) {
576 bool should_try_gc;
577 uint gc_count_before;
578
579 {
580 MutexLockerEx x(Heap_lock);
581 result = _allocator->attempt_allocation_locked(word_size, context);
582 if (result != NULL) {
583 return result;
584 }
585
586 if (GC_locker::is_active_and_needs_gc()) {
587 if (g1_policy()->can_expand_young_list()) {
588 // No need for an ergo verbose message here,
589 // can_expand_young_list() does this when it returns true.
590 result = _allocator->attempt_allocation_force(word_size, context);
591 if (result != NULL) {
592 return result;
593 }
594 }
595 should_try_gc = false;
596 } else {
597 // The GCLocker may not be active but the GCLocker initiated
598 // GC may not yet have been performed (GCLocker::needs_gc()
599 // returns true). In this case we do not try this GC and
600 // wait until the GCLocker initiated GC is performed, and
601 // then retry the allocation.
602 if (GC_locker::needs_gc()) {
603 should_try_gc = false;
604 } else {
605 // Read the GC count while still holding the Heap_lock.
606 gc_count_before = total_collections();
607 should_try_gc = true;
608 }
609 }
610 }
611
612 if (should_try_gc) {
613 bool succeeded;
614 result = do_collection_pause(word_size, gc_count_before, &succeeded,
615 GCCause::_g1_inc_collection_pause);
616 if (result != NULL) {
617 assert(succeeded, "only way to get back a non-NULL result");
618 return result;
619 }
620
621 if (succeeded) {
622 // If we get here we successfully scheduled a collection which
623 // failed to allocate. No point in trying to allocate
624 // further. We'll just return NULL.
625 MutexLockerEx x(Heap_lock);
626 *gc_count_before_ret = total_collections();
627 return NULL;
628 }
629 } else {
630 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
631 MutexLockerEx x(Heap_lock);
632 *gc_count_before_ret = total_collections();
633 return NULL;
634 }
635 // The GCLocker is either active or the GCLocker initiated
636 // GC has not yet been performed. Stall until it is and
637 // then retry the allocation.
638 GC_locker::stall_until_clear();
639 (*gclocker_retry_count_ret) += 1;
640 }
641
642 // We can reach here if we were unsuccessful in scheduling a
643 // collection (because another thread beat us to it) or if we were
644 // stalled due to the GC locker. In either can we should retry the
645 // allocation attempt in case another thread successfully
646 // performed a collection and reclaimed enough space. We do the
647 // first attempt (without holding the Heap_lock) here and the
648 // follow-on attempt will be at the start of the next loop
649 // iteration (after taking the Heap_lock).
650 result = _allocator->attempt_allocation(word_size, context);
651 if (result != NULL) {
652 return result;
653 }
654
655 // Give a warning if we seem to be looping forever.
656 if ((QueuedAllocationWarningCount > 0) &&
657 (try_count % QueuedAllocationWarningCount == 0)) {
658 warning("G1CollectedHeap::attempt_allocation_slow() "
659 "retries %d times", try_count);
660 }
661 }
662
663 ShouldNotReachHere();
664 return NULL;
665 }
666
667 void G1CollectedHeap::begin_archive_alloc_range() {
668 assert_at_safepoint(true /* should_be_vm_thread */);
669 if (_archive_allocator == NULL) {
670 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
671 }
672 }
673
674 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
675 // Allocations in archive regions cannot be of a size that would be considered
676 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
677 // may be different at archive-restore time.
678 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
679 }
680
681 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
682 assert_at_safepoint(true /* should_be_vm_thread */);
683 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
684 if (is_archive_alloc_too_large(word_size)) {
685 return NULL;
686 }
687 return _archive_allocator->archive_mem_allocate(word_size);
688 }
689
690 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
691 size_t end_alignment_in_bytes) {
692 assert_at_safepoint(true /* should_be_vm_thread */);
693 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
694
695 // Call complete_archive to do the real work, filling in the MemRegion
696 // array with the archive regions.
697 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
698 delete _archive_allocator;
699 _archive_allocator = NULL;
700 }
701
702 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
703 assert(ranges != NULL, "MemRegion array NULL");
704 assert(count != 0, "No MemRegions provided");
705 MemRegion reserved = _hrm.reserved();
706 for (size_t i = 0; i < count; i++) {
707 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
708 return false;
709 }
710 }
711 return true;
712 }
713
714 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
715 assert(!is_init_completed(), "Expect to be called at JVM init time");
716 assert(ranges != NULL, "MemRegion array NULL");
717 assert(count != 0, "No MemRegions provided");
718 MutexLockerEx x(Heap_lock);
719
720 MemRegion reserved = _hrm.reserved();
721 HeapWord* prev_last_addr = NULL;
722 HeapRegion* prev_last_region = NULL;
723
724 // Temporarily disable pretouching of heap pages. This interface is used
725 // when mmap'ing archived heap data in, so pre-touching is wasted.
726 FlagSetting fs(AlwaysPreTouch, false);
727
728 // Enable archive object checking in G1MarkSweep. We have to let it know
729 // about each archive range, so that objects in those ranges aren't marked.
730 G1MarkSweep::enable_archive_object_check();
731
732 // For each specified MemRegion range, allocate the corresponding G1
733 // regions and mark them as archive regions. We expect the ranges in
734 // ascending starting address order, without overlap.
735 for (size_t i = 0; i < count; i++) {
736 MemRegion curr_range = ranges[i];
737 HeapWord* start_address = curr_range.start();
738 size_t word_size = curr_range.word_size();
739 HeapWord* last_address = curr_range.last();
740 size_t commits = 0;
741
742 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
743 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
744 p2i(start_address), p2i(last_address));
745 guarantee(start_address > prev_last_addr,
746 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
747 p2i(start_address), p2i(prev_last_addr));
748 prev_last_addr = last_address;
749
750 // Check for ranges that start in the same G1 region in which the previous
751 // range ended, and adjust the start address so we don't try to allocate
752 // the same region again. If the current range is entirely within that
753 // region, skip it, just adjusting the recorded top.
754 HeapRegion* start_region = _hrm.addr_to_region(start_address);
755 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
756 start_address = start_region->end();
757 if (start_address > last_address) {
758 increase_used(word_size * HeapWordSize);
759 start_region->set_top(last_address + 1);
760 continue;
761 }
762 start_region->set_top(start_address);
763 curr_range = MemRegion(start_address, last_address + 1);
764 start_region = _hrm.addr_to_region(start_address);
765 }
766
767 // Perform the actual region allocation, exiting if it fails.
768 // Then note how much new space we have allocated.
769 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
770 return false;
771 }
772 increase_used(word_size * HeapWordSize);
773 if (commits != 0) {
774 ergo_verbose1(ErgoHeapSizing,
775 "attempt heap expansion",
776 ergo_format_reason("allocate archive regions")
777 ergo_format_byte("total size"),
778 HeapRegion::GrainWords * HeapWordSize * commits);
779 }
780
781 // Mark each G1 region touched by the range as archive, add it to the old set,
782 // and set the allocation context and top.
783 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
784 HeapRegion* last_region = _hrm.addr_to_region(last_address);
785 prev_last_region = last_region;
786
787 while (curr_region != NULL) {
788 assert(curr_region->is_empty() && !curr_region->is_pinned(),
789 "Region already in use (index %u)", curr_region->hrm_index());
790 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
791 curr_region->set_allocation_context(AllocationContext::system());
792 curr_region->set_archive();
793 _old_set.add(curr_region);
794 if (curr_region != last_region) {
795 curr_region->set_top(curr_region->end());
796 curr_region = _hrm.next_region_in_heap(curr_region);
797 } else {
798 curr_region->set_top(last_address + 1);
799 curr_region = NULL;
800 }
801 }
802
803 // Notify mark-sweep of the archive range.
804 G1MarkSweep::set_range_archive(curr_range, true);
805 }
806 return true;
807 }
808
809 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
810 assert(!is_init_completed(), "Expect to be called at JVM init time");
811 assert(ranges != NULL, "MemRegion array NULL");
812 assert(count != 0, "No MemRegions provided");
813 MemRegion reserved = _hrm.reserved();
814 HeapWord *prev_last_addr = NULL;
815 HeapRegion* prev_last_region = NULL;
816
817 // For each MemRegion, create filler objects, if needed, in the G1 regions
818 // that contain the address range. The address range actually within the
819 // MemRegion will not be modified. That is assumed to have been initialized
820 // elsewhere, probably via an mmap of archived heap data.
821 MutexLockerEx x(Heap_lock);
822 for (size_t i = 0; i < count; i++) {
823 HeapWord* start_address = ranges[i].start();
824 HeapWord* last_address = ranges[i].last();
825
826 assert(reserved.contains(start_address) && reserved.contains(last_address),
827 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
828 p2i(start_address), p2i(last_address));
829 assert(start_address > prev_last_addr,
830 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
831 p2i(start_address), p2i(prev_last_addr));
832
833 HeapRegion* start_region = _hrm.addr_to_region(start_address);
834 HeapRegion* last_region = _hrm.addr_to_region(last_address);
835 HeapWord* bottom_address = start_region->bottom();
836
837 // Check for a range beginning in the same region in which the
838 // previous one ended.
839 if (start_region == prev_last_region) {
840 bottom_address = prev_last_addr + 1;
841 }
842
843 // Verify that the regions were all marked as archive regions by
844 // alloc_archive_regions.
845 HeapRegion* curr_region = start_region;
846 while (curr_region != NULL) {
847 guarantee(curr_region->is_archive(),
848 "Expected archive region at index %u", curr_region->hrm_index());
849 if (curr_region != last_region) {
850 curr_region = _hrm.next_region_in_heap(curr_region);
851 } else {
852 curr_region = NULL;
853 }
854 }
855
856 prev_last_addr = last_address;
857 prev_last_region = last_region;
858
859 // Fill the memory below the allocated range with dummy object(s),
860 // if the region bottom does not match the range start, or if the previous
861 // range ended within the same G1 region, and there is a gap.
862 if (start_address != bottom_address) {
863 size_t fill_size = pointer_delta(start_address, bottom_address);
864 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
865 increase_used(fill_size * HeapWordSize);
866 }
867 }
868 }
869
870 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
871 uint* gc_count_before_ret,
872 uint* gclocker_retry_count_ret) {
873 assert_heap_not_locked_and_not_at_safepoint();
874 assert(!is_humongous(word_size), "attempt_allocation() should not "
875 "be called for humongous allocation requests");
876
877 AllocationContext_t context = AllocationContext::current();
878 HeapWord* result = _allocator->attempt_allocation(word_size, context);
879
880 if (result == NULL) {
881 result = attempt_allocation_slow(word_size,
882 context,
883 gc_count_before_ret,
884 gclocker_retry_count_ret);
885 }
886 assert_heap_not_locked();
887 if (result != NULL) {
888 dirty_young_block(result, word_size);
889 }
890 return result;
891 }
892
893 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
894 assert(!is_init_completed(), "Expect to be called at JVM init time");
895 assert(ranges != NULL, "MemRegion array NULL");
896 assert(count != 0, "No MemRegions provided");
897 MemRegion reserved = _hrm.reserved();
898 HeapWord* prev_last_addr = NULL;
899 HeapRegion* prev_last_region = NULL;
900 size_t size_used = 0;
901 size_t uncommitted_regions = 0;
902
903 // For each Memregion, free the G1 regions that constitute it, and
904 // notify mark-sweep that the range is no longer to be considered 'archive.'
905 MutexLockerEx x(Heap_lock);
906 for (size_t i = 0; i < count; i++) {
907 HeapWord* start_address = ranges[i].start();
908 HeapWord* last_address = ranges[i].last();
909
910 assert(reserved.contains(start_address) && reserved.contains(last_address),
911 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
912 p2i(start_address), p2i(last_address));
913 assert(start_address > prev_last_addr,
914 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
915 p2i(start_address), p2i(prev_last_addr));
916 size_used += ranges[i].byte_size();
917 prev_last_addr = last_address;
918
919 HeapRegion* start_region = _hrm.addr_to_region(start_address);
920 HeapRegion* last_region = _hrm.addr_to_region(last_address);
921
922 // Check for ranges that start in the same G1 region in which the previous
923 // range ended, and adjust the start address so we don't try to free
924 // the same region again. If the current range is entirely within that
925 // region, skip it.
926 if (start_region == prev_last_region) {
927 start_address = start_region->end();
928 if (start_address > last_address) {
929 continue;
930 }
931 start_region = _hrm.addr_to_region(start_address);
932 }
933 prev_last_region = last_region;
934
935 // After verifying that each region was marked as an archive region by
936 // alloc_archive_regions, set it free and empty and uncommit it.
937 HeapRegion* curr_region = start_region;
938 while (curr_region != NULL) {
939 guarantee(curr_region->is_archive(),
940 "Expected archive region at index %u", curr_region->hrm_index());
941 uint curr_index = curr_region->hrm_index();
942 _old_set.remove(curr_region);
943 curr_region->set_free();
944 curr_region->set_top(curr_region->bottom());
945 if (curr_region != last_region) {
946 curr_region = _hrm.next_region_in_heap(curr_region);
947 } else {
948 curr_region = NULL;
949 }
950 _hrm.shrink_at(curr_index, 1);
951 uncommitted_regions++;
952 }
953
954 // Notify mark-sweep that this is no longer an archive range.
955 G1MarkSweep::set_range_archive(ranges[i], false);
956 }
957
958 if (uncommitted_regions != 0) {
959 ergo_verbose1(ErgoHeapSizing,
960 "attempt heap shrinking",
961 ergo_format_reason("uncommitted archive regions")
962 ergo_format_byte("total size"),
963 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
964 }
965 decrease_used(size_used);
966 }
967
968 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
969 uint* gc_count_before_ret,
970 uint* gclocker_retry_count_ret) {
971 // The structure of this method has a lot of similarities to
972 // attempt_allocation_slow(). The reason these two were not merged
973 // into a single one is that such a method would require several "if
974 // allocation is not humongous do this, otherwise do that"
975 // conditional paths which would obscure its flow. In fact, an early
976 // version of this code did use a unified method which was harder to
977 // follow and, as a result, it had subtle bugs that were hard to
978 // track down. So keeping these two methods separate allows each to
979 // be more readable. It will be good to keep these two in sync as
980 // much as possible.
981
982 assert_heap_not_locked_and_not_at_safepoint();
983 assert(is_humongous(word_size), "attempt_allocation_humongous() "
984 "should only be called for humongous allocations");
985
986 // Humongous objects can exhaust the heap quickly, so we should check if we
987 // need to start a marking cycle at each humongous object allocation. We do
988 // the check before we do the actual allocation. The reason for doing it
989 // before the allocation is that we avoid having to keep track of the newly
990 // allocated memory while we do a GC.
991 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
992 word_size)) {
993 collect(GCCause::_g1_humongous_allocation);
994 }
995
996 // We will loop until a) we manage to successfully perform the
997 // allocation or b) we successfully schedule a collection which
998 // fails to perform the allocation. b) is the only case when we'll
999 // return NULL.
1000 HeapWord* result = NULL;
1001 for (int try_count = 1; /* we'll return */; try_count += 1) {
1002 bool should_try_gc;
1003 uint gc_count_before;
1004
1005 {
1006 MutexLockerEx x(Heap_lock);
1007
1008 // Given that humongous objects are not allocated in young
1009 // regions, we'll first try to do the allocation without doing a
1010 // collection hoping that there's enough space in the heap.
1011 result = humongous_obj_allocate(word_size, AllocationContext::current());
1012 if (result != NULL) {
1013 return result;
1014 }
1015
1016 if (GC_locker::is_active_and_needs_gc()) {
1017 should_try_gc = false;
1018 } else {
1019 // The GCLocker may not be active but the GCLocker initiated
1020 // GC may not yet have been performed (GCLocker::needs_gc()
1021 // returns true). In this case we do not try this GC and
1022 // wait until the GCLocker initiated GC is performed, and
1023 // then retry the allocation.
1024 if (GC_locker::needs_gc()) {
1025 should_try_gc = false;
1026 } else {
1027 // Read the GC count while still holding the Heap_lock.
1028 gc_count_before = total_collections();
1029 should_try_gc = true;
1030 }
1031 }
1032 }
1033
1034 if (should_try_gc) {
1035 // If we failed to allocate the humongous object, we should try to
1036 // do a collection pause (if we're allowed) in case it reclaims
1037 // enough space for the allocation to succeed after the pause.
1038
1039 bool succeeded;
1040 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1041 GCCause::_g1_humongous_allocation);
1042 if (result != NULL) {
1043 assert(succeeded, "only way to get back a non-NULL result");
1044 return result;
1045 }
1046
1047 if (succeeded) {
1048 // If we get here we successfully scheduled a collection which
1049 // failed to allocate. No point in trying to allocate
1050 // further. We'll just return NULL.
1051 MutexLockerEx x(Heap_lock);
1052 *gc_count_before_ret = total_collections();
1053 return NULL;
1054 }
1055 } else {
1056 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1057 MutexLockerEx x(Heap_lock);
1058 *gc_count_before_ret = total_collections();
1059 return NULL;
1060 }
1061 // The GCLocker is either active or the GCLocker initiated
1062 // GC has not yet been performed. Stall until it is and
1063 // then retry the allocation.
1064 GC_locker::stall_until_clear();
1065 (*gclocker_retry_count_ret) += 1;
1066 }
1067
1068 // We can reach here if we were unsuccessful in scheduling a
1069 // collection (because another thread beat us to it) or if we were
1070 // stalled due to the GC locker. In either can we should retry the
1071 // allocation attempt in case another thread successfully
1072 // performed a collection and reclaimed enough space. Give a
1073 // warning if we seem to be looping forever.
1074
1075 if ((QueuedAllocationWarningCount > 0) &&
1076 (try_count % QueuedAllocationWarningCount == 0)) {
1077 warning("G1CollectedHeap::attempt_allocation_humongous() "
1078 "retries %d times", try_count);
1079 }
1080 }
1081
1082 ShouldNotReachHere();
1083 return NULL;
1084 }
1085
1086 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1087 AllocationContext_t context,
1088 bool expect_null_mutator_alloc_region) {
1089 assert_at_safepoint(true /* should_be_vm_thread */);
1090 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1091 "the current alloc region was unexpectedly found to be non-NULL");
1092
1093 if (!is_humongous(word_size)) {
1094 return _allocator->attempt_allocation_locked(word_size, context);
1095 } else {
1096 HeapWord* result = humongous_obj_allocate(word_size, context);
1097 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1098 collector_state()->set_initiate_conc_mark_if_possible(true);
1099 }
1100 return result;
1101 }
1102
1103 ShouldNotReachHere();
1104 }
1105
1106 class PostMCRemSetClearClosure: public HeapRegionClosure {
1107 G1CollectedHeap* _g1h;
1108 ModRefBarrierSet* _mr_bs;
1109 public:
1110 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1111 _g1h(g1h), _mr_bs(mr_bs) {}
1112
1113 bool doHeapRegion(HeapRegion* r) {
1114 HeapRegionRemSet* hrrs = r->rem_set();
1115
1116 _g1h->reset_gc_time_stamps(r);
1117
1118 if (r->is_continues_humongous()) {
1119 // We'll assert that the strong code root list and RSet is empty
1120 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1121 assert(hrrs->occupied() == 0, "RSet should be empty");
1122 } else {
1123 hrrs->clear();
1124 }
1125 // You might think here that we could clear just the cards
1126 // corresponding to the used region. But no: if we leave a dirty card
1127 // in a region we might allocate into, then it would prevent that card
1128 // from being enqueued, and cause it to be missed.
1129 // Re: the performance cost: we shouldn't be doing full GC anyway!
1130 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1131
1132 return false;
1133 }
1134 };
1135
1136 void G1CollectedHeap::clear_rsets_post_compaction() {
1137 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1138 heap_region_iterate(&rs_clear);
1139 }
1140
1141 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1142 G1CollectedHeap* _g1h;
1143 UpdateRSOopClosure _cl;
1144 public:
1145 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1146 _cl(g1->g1_rem_set(), worker_i),
1147 _g1h(g1)
1148 { }
1149
1150 bool doHeapRegion(HeapRegion* r) {
1151 if (!r->is_continues_humongous()) {
1152 _cl.set_from(r);
1153 r->oop_iterate(&_cl);
1154 }
1155 return false;
1156 }
1157 };
1158
1159 class ParRebuildRSTask: public AbstractGangTask {
1160 G1CollectedHeap* _g1;
1161 HeapRegionClaimer _hrclaimer;
1162
1163 public:
1164 ParRebuildRSTask(G1CollectedHeap* g1) :
1165 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1166
1167 void work(uint worker_id) {
1168 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1169 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1170 }
1171 };
1172
1173 class PostCompactionPrinterClosure: public HeapRegionClosure {
1174 private:
1175 G1HRPrinter* _hr_printer;
1176 public:
1177 bool doHeapRegion(HeapRegion* hr) {
1178 assert(!hr->is_young(), "not expecting to find young regions");
1179 if (hr->is_free()) {
1180 // We only generate output for non-empty regions.
1181 } else if (hr->is_starts_humongous()) {
1182 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1183 } else if (hr->is_continues_humongous()) {
1184 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1185 } else if (hr->is_archive()) {
1186 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1187 } else if (hr->is_old()) {
1188 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1189 } else {
1190 ShouldNotReachHere();
1191 }
1192 return false;
1193 }
1194
1195 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1196 : _hr_printer(hr_printer) { }
1197 };
1198
1199 void G1CollectedHeap::print_hrm_post_compaction() {
1200 PostCompactionPrinterClosure cl(hr_printer());
1201 heap_region_iterate(&cl);
1202 }
1203
1204 bool G1CollectedHeap::do_collection(bool explicit_gc,
1205 bool clear_all_soft_refs,
1206 size_t word_size) {
1207 assert_at_safepoint(true /* should_be_vm_thread */);
1208
1209 if (GC_locker::check_active_before_gc()) {
1210 return false;
1211 }
1212
1213 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1214 gc_timer->register_gc_start();
1215
1216 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1217 GCIdMark gc_id_mark;
1218 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1219
1220 SvcGCMarker sgcm(SvcGCMarker::FULL);
1221 ResourceMark rm;
1222
1223 G1Log::update_level();
1224 print_heap_before_gc();
1225 trace_heap_before_gc(gc_tracer);
1226
1227 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1228
1229 verify_region_sets_optional();
1230
1231 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1232 collector_policy()->should_clear_all_soft_refs();
1233
1234 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1235
1236 {
1237 IsGCActiveMark x;
1238
1239 // Timing
1240 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1241 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1242
1243 {
1244 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1245 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1246 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1247
1248 g1_policy()->record_full_collection_start();
1249
1250 // Note: When we have a more flexible GC logging framework that
1251 // allows us to add optional attributes to a GC log record we
1252 // could consider timing and reporting how long we wait in the
1253 // following two methods.
1254 wait_while_free_regions_coming();
1255 // If we start the compaction before the CM threads finish
1256 // scanning the root regions we might trip them over as we'll
1257 // be moving objects / updating references. So let's wait until
1258 // they are done. By telling them to abort, they should complete
1259 // early.
1260 _cm->root_regions()->abort();
1261 _cm->root_regions()->wait_until_scan_finished();
1262 append_secondary_free_list_if_not_empty_with_lock();
1263
1264 gc_prologue(true);
1265 increment_total_collections(true /* full gc */);
1266 increment_old_marking_cycles_started();
1267
1268 assert(used() == recalculate_used(), "Should be equal");
1269
1270 verify_before_gc();
1271
1272 check_bitmaps("Full GC Start");
1273 pre_full_gc_dump(gc_timer);
1274
1275 #if defined(COMPILER2) || INCLUDE_JVMCI
1276 DerivedPointerTable::clear();
1277 #endif
1278
1279 // Disable discovery and empty the discovered lists
1280 // for the CM ref processor.
1281 ref_processor_cm()->disable_discovery();
1282 ref_processor_cm()->abandon_partial_discovery();
1283 ref_processor_cm()->verify_no_references_recorded();
1284
1285 // Abandon current iterations of concurrent marking and concurrent
1286 // refinement, if any are in progress. We have to do this before
1287 // wait_until_scan_finished() below.
1288 concurrent_mark()->abort();
1289
1290 // Make sure we'll choose a new allocation region afterwards.
1291 _allocator->release_mutator_alloc_region();
1292 _allocator->abandon_gc_alloc_regions();
1293 g1_rem_set()->cleanupHRRS();
1294
1295 // We should call this after we retire any currently active alloc
1296 // regions so that all the ALLOC / RETIRE events are generated
1297 // before the start GC event.
1298 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1299
1300 // We may have added regions to the current incremental collection
1301 // set between the last GC or pause and now. We need to clear the
1302 // incremental collection set and then start rebuilding it afresh
1303 // after this full GC.
1304 abandon_collection_set(g1_policy()->inc_cset_head());
1305 g1_policy()->clear_incremental_cset();
1306 g1_policy()->stop_incremental_cset_building();
1307
1308 tear_down_region_sets(false /* free_list_only */);
1309 collector_state()->set_gcs_are_young(true);
1310
1311 // See the comments in g1CollectedHeap.hpp and
1312 // G1CollectedHeap::ref_processing_init() about
1313 // how reference processing currently works in G1.
1314
1315 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1316 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1317
1318 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1319 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1320
1321 ref_processor_stw()->enable_discovery();
1322 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1323
1324 // Do collection work
1325 {
1326 HandleMark hm; // Discard invalid handles created during gc
1327 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1328 }
1329
1330 assert(num_free_regions() == 0, "we should not have added any free regions");
1331 rebuild_region_sets(false /* free_list_only */);
1332
1333 // Enqueue any discovered reference objects that have
1334 // not been removed from the discovered lists.
1335 ref_processor_stw()->enqueue_discovered_references();
1336
1337 #if defined(COMPILER2) || INCLUDE_JVMCI
1338 DerivedPointerTable::update_pointers();
1339 #endif
1340
1341 MemoryService::track_memory_usage();
1342
1343 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1344 ref_processor_stw()->verify_no_references_recorded();
1345
1346 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1347 ClassLoaderDataGraph::purge();
1348 MetaspaceAux::verify_metrics();
1349
1350 // Note: since we've just done a full GC, concurrent
1351 // marking is no longer active. Therefore we need not
1352 // re-enable reference discovery for the CM ref processor.
1353 // That will be done at the start of the next marking cycle.
1354 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1355 ref_processor_cm()->verify_no_references_recorded();
1356
1357 reset_gc_time_stamp();
1358 // Since everything potentially moved, we will clear all remembered
1359 // sets, and clear all cards. Later we will rebuild remembered
1360 // sets. We will also reset the GC time stamps of the regions.
1361 clear_rsets_post_compaction();
1362 check_gc_time_stamps();
1363
1364 // Resize the heap if necessary.
1365 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1366
1367 if (_hr_printer.is_active()) {
1368 // We should do this after we potentially resize the heap so
1369 // that all the COMMIT / UNCOMMIT events are generated before
1370 // the end GC event.
1371
1372 print_hrm_post_compaction();
1373 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1374 }
1375
1376 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1377 if (hot_card_cache->use_cache()) {
1378 hot_card_cache->reset_card_counts();
1379 hot_card_cache->reset_hot_cache();
1380 }
1381
1382 // Rebuild remembered sets of all regions.
1383 uint n_workers =
1384 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1385 workers()->active_workers(),
1386 Threads::number_of_non_daemon_threads());
1387 workers()->set_active_workers(n_workers);
1388
1389 ParRebuildRSTask rebuild_rs_task(this);
1390 workers()->run_task(&rebuild_rs_task);
1391
1392 // Rebuild the strong code root lists for each region
1393 rebuild_strong_code_roots();
1394
1395 if (true) { // FIXME
1396 MetaspaceGC::compute_new_size();
1397 }
1398
1399 #ifdef TRACESPINNING
1400 ParallelTaskTerminator::print_termination_counts();
1401 #endif
1402
1403 // Discard all rset updates
1404 JavaThread::dirty_card_queue_set().abandon_logs();
1405 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1406
1407 _young_list->reset_sampled_info();
1408 // At this point there should be no regions in the
1409 // entire heap tagged as young.
1410 assert(check_young_list_empty(true /* check_heap */),
1411 "young list should be empty at this point");
1412
1413 // Update the number of full collections that have been completed.
1414 increment_old_marking_cycles_completed(false /* concurrent */);
1415
1416 _hrm.verify_optional();
1417 verify_region_sets_optional();
1418
1419 verify_after_gc();
1420
1421 // Clear the previous marking bitmap, if needed for bitmap verification.
1422 // Note we cannot do this when we clear the next marking bitmap in
1423 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1424 // objects marked during a full GC against the previous bitmap.
1425 // But we need to clear it before calling check_bitmaps below since
1426 // the full GC has compacted objects and updated TAMS but not updated
1427 // the prev bitmap.
1428 if (G1VerifyBitmaps) {
1429 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1430 }
1431 check_bitmaps("Full GC End");
1432
1433 // Start a new incremental collection set for the next pause
1434 assert(g1_policy()->collection_set() == NULL, "must be");
1435 g1_policy()->start_incremental_cset_building();
1436
1437 clear_cset_fast_test();
1438
1439 _allocator->init_mutator_alloc_region();
1440
1441 g1_policy()->record_full_collection_end();
1442
1443 if (G1Log::fine()) {
1444 g1_policy()->print_heap_transition();
1445 }
1446
1447 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1448 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1449 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1450 // before any GC notifications are raised.
1451 g1mm()->update_sizes();
1452
1453 gc_epilogue(true);
1454 }
1455
1456 if (G1Log::finer()) {
1457 g1_policy()->print_detailed_heap_transition(true /* full */);
1458 }
1459
1460 print_heap_after_gc();
1461 trace_heap_after_gc(gc_tracer);
1462
1463 post_full_gc_dump(gc_timer);
1464
1465 gc_timer->register_gc_end();
1466 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1467 }
1468
1469 return true;
1470 }
1471
1472 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1473 // do_collection() will return whether it succeeded in performing
1474 // the GC. Currently, there is no facility on the
1475 // do_full_collection() API to notify the caller than the collection
1476 // did not succeed (e.g., because it was locked out by the GC
1477 // locker). So, right now, we'll ignore the return value.
1478 bool dummy = do_collection(true, /* explicit_gc */
1479 clear_all_soft_refs,
1480 0 /* word_size */);
1481 }
1482
1483 // This code is mostly copied from TenuredGeneration.
1484 void
1485 G1CollectedHeap::
1486 resize_if_necessary_after_full_collection(size_t word_size) {
1487 // Include the current allocation, if any, and bytes that will be
1488 // pre-allocated to support collections, as "used".
1489 const size_t used_after_gc = used();
1490 const size_t capacity_after_gc = capacity();
1491 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1492
1493 // This is enforced in arguments.cpp.
1494 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1495 "otherwise the code below doesn't make sense");
1496
1497 // We don't have floating point command-line arguments
1498 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1499 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1500 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1501 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1502
1503 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1504 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1505
1506 // We have to be careful here as these two calculations can overflow
1507 // 32-bit size_t's.
1508 double used_after_gc_d = (double) used_after_gc;
1509 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1510 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1511
1512 // Let's make sure that they are both under the max heap size, which
1513 // by default will make them fit into a size_t.
1514 double desired_capacity_upper_bound = (double) max_heap_size;
1515 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1516 desired_capacity_upper_bound);
1517 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1518 desired_capacity_upper_bound);
1519
1520 // We can now safely turn them into size_t's.
1521 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1522 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1523
1524 // This assert only makes sense here, before we adjust them
1525 // with respect to the min and max heap size.
1526 assert(minimum_desired_capacity <= maximum_desired_capacity,
1527 "minimum_desired_capacity = " SIZE_FORMAT ", "
1528 "maximum_desired_capacity = " SIZE_FORMAT,
1529 minimum_desired_capacity, maximum_desired_capacity);
1530
1531 // Should not be greater than the heap max size. No need to adjust
1532 // it with respect to the heap min size as it's a lower bound (i.e.,
1533 // we'll try to make the capacity larger than it, not smaller).
1534 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1535 // Should not be less than the heap min size. No need to adjust it
1536 // with respect to the heap max size as it's an upper bound (i.e.,
1537 // we'll try to make the capacity smaller than it, not greater).
1538 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1539
1540 if (capacity_after_gc < minimum_desired_capacity) {
1541 // Don't expand unless it's significant
1542 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1543 ergo_verbose4(ErgoHeapSizing,
1544 "attempt heap expansion",
1545 ergo_format_reason("capacity lower than "
1546 "min desired capacity after Full GC")
1547 ergo_format_byte("capacity")
1548 ergo_format_byte("occupancy")
1549 ergo_format_byte_perc("min desired capacity"),
1550 capacity_after_gc, used_after_gc,
1551 minimum_desired_capacity, (double) MinHeapFreeRatio);
1552 expand(expand_bytes);
1553
1554 // No expansion, now see if we want to shrink
1555 } else if (capacity_after_gc > maximum_desired_capacity) {
1556 // Capacity too large, compute shrinking size
1557 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1558 ergo_verbose4(ErgoHeapSizing,
1559 "attempt heap shrinking",
1560 ergo_format_reason("capacity higher than "
1561 "max desired capacity after Full GC")
1562 ergo_format_byte("capacity")
1563 ergo_format_byte("occupancy")
1564 ergo_format_byte_perc("max desired capacity"),
1565 capacity_after_gc, used_after_gc,
1566 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1567 shrink(shrink_bytes);
1568 }
1569 }
1570
1571 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1572 AllocationContext_t context,
1573 bool do_gc,
1574 bool clear_all_soft_refs,
1575 bool expect_null_mutator_alloc_region,
1576 bool* gc_succeeded) {
1577 *gc_succeeded = true;
1578 // Let's attempt the allocation first.
1579 HeapWord* result =
1580 attempt_allocation_at_safepoint(word_size,
1581 context,
1582 expect_null_mutator_alloc_region);
1583 if (result != NULL) {
1584 assert(*gc_succeeded, "sanity");
1585 return result;
1586 }
1587
1588 // In a G1 heap, we're supposed to keep allocation from failing by
1589 // incremental pauses. Therefore, at least for now, we'll favor
1590 // expansion over collection. (This might change in the future if we can
1591 // do something smarter than full collection to satisfy a failed alloc.)
1592 result = expand_and_allocate(word_size, context);
1593 if (result != NULL) {
1594 assert(*gc_succeeded, "sanity");
1595 return result;
1596 }
1597
1598 if (do_gc) {
1599 // Expansion didn't work, we'll try to do a Full GC.
1600 *gc_succeeded = do_collection(false, /* explicit_gc */
1601 clear_all_soft_refs,
1602 word_size);
1603 }
1604
1605 return NULL;
1606 }
1607
1608 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1609 AllocationContext_t context,
1610 bool* succeeded) {
1611 assert_at_safepoint(true /* should_be_vm_thread */);
1612
1613 // Attempts to allocate followed by Full GC.
1614 HeapWord* result =
1615 satisfy_failed_allocation_helper(word_size,
1616 context,
1617 true, /* do_gc */
1618 false, /* clear_all_soft_refs */
1619 false, /* expect_null_mutator_alloc_region */
1620 succeeded);
1621
1622 if (result != NULL || !*succeeded) {
1623 return result;
1624 }
1625
1626 // Attempts to allocate followed by Full GC that will collect all soft references.
1627 result = satisfy_failed_allocation_helper(word_size,
1628 context,
1629 true, /* do_gc */
1630 true, /* clear_all_soft_refs */
1631 true, /* expect_null_mutator_alloc_region */
1632 succeeded);
1633
1634 if (result != NULL || !*succeeded) {
1635 return result;
1636 }
1637
1638 // Attempts to allocate, no GC
1639 result = satisfy_failed_allocation_helper(word_size,
1640 context,
1641 false, /* do_gc */
1642 false, /* clear_all_soft_refs */
1643 true, /* expect_null_mutator_alloc_region */
1644 succeeded);
1645
1646 if (result != NULL) {
1647 assert(*succeeded, "sanity");
1648 return result;
1649 }
1650
1651 assert(!collector_policy()->should_clear_all_soft_refs(),
1652 "Flag should have been handled and cleared prior to this point");
1653
1654 // What else? We might try synchronous finalization later. If the total
1655 // space available is large enough for the allocation, then a more
1656 // complete compaction phase than we've tried so far might be
1657 // appropriate.
1658 assert(*succeeded, "sanity");
1659 return NULL;
1660 }
1661
1662 // Attempting to expand the heap sufficiently
1663 // to support an allocation of the given "word_size". If
1664 // successful, perform the allocation and return the address of the
1665 // allocated block, or else "NULL".
1666
1667 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1668 assert_at_safepoint(true /* should_be_vm_thread */);
1669
1670 verify_region_sets_optional();
1671
1672 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1673 ergo_verbose1(ErgoHeapSizing,
1674 "attempt heap expansion",
1675 ergo_format_reason("allocation request failed")
1676 ergo_format_byte("allocation request"),
1677 word_size * HeapWordSize);
1678 if (expand(expand_bytes)) {
1679 _hrm.verify_optional();
1680 verify_region_sets_optional();
1681 return attempt_allocation_at_safepoint(word_size,
1682 context,
1683 false /* expect_null_mutator_alloc_region */);
1684 }
1685 return NULL;
1686 }
1687
1688 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1689 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1690 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1691 HeapRegion::GrainBytes);
1692 ergo_verbose2(ErgoHeapSizing,
1693 "expand the heap",
1694 ergo_format_byte("requested expansion amount")
1695 ergo_format_byte("attempted expansion amount"),
1696 expand_bytes, aligned_expand_bytes);
1697
1698 if (is_maximal_no_gc()) {
1699 ergo_verbose0(ErgoHeapSizing,
1700 "did not expand the heap",
1701 ergo_format_reason("heap already fully expanded"));
1702 return false;
1703 }
1704
1705 double expand_heap_start_time_sec = os::elapsedTime();
1706 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1707 assert(regions_to_expand > 0, "Must expand by at least one region");
1708
1709 uint expanded_by = _hrm.expand_by(regions_to_expand);
1710 if (expand_time_ms != NULL) {
1711 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1712 }
1713
1714 if (expanded_by > 0) {
1715 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1716 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1717 g1_policy()->record_new_heap_size(num_regions());
1718 } else {
1719 ergo_verbose0(ErgoHeapSizing,
1720 "did not expand the heap",
1721 ergo_format_reason("heap expansion operation failed"));
1722 // The expansion of the virtual storage space was unsuccessful.
1723 // Let's see if it was because we ran out of swap.
1724 if (G1ExitOnExpansionFailure &&
1725 _hrm.available() >= regions_to_expand) {
1726 // We had head room...
1727 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1728 }
1729 }
1730 return regions_to_expand > 0;
1731 }
1732
1733 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1734 size_t aligned_shrink_bytes =
1735 ReservedSpace::page_align_size_down(shrink_bytes);
1736 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1737 HeapRegion::GrainBytes);
1738 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1739
1740 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1741 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1742
1743 ergo_verbose3(ErgoHeapSizing,
1744 "shrink the heap",
1745 ergo_format_byte("requested shrinking amount")
1746 ergo_format_byte("aligned shrinking amount")
1747 ergo_format_byte("attempted shrinking amount"),
1748 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1749 if (num_regions_removed > 0) {
1750 g1_policy()->record_new_heap_size(num_regions());
1751 } else {
1752 ergo_verbose0(ErgoHeapSizing,
1753 "did not shrink the heap",
1754 ergo_format_reason("heap shrinking operation failed"));
1755 }
1756 }
1757
1758 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1759 verify_region_sets_optional();
1760
1761 // We should only reach here at the end of a Full GC which means we
1762 // should not not be holding to any GC alloc regions. The method
1763 // below will make sure of that and do any remaining clean up.
1764 _allocator->abandon_gc_alloc_regions();
1765
1766 // Instead of tearing down / rebuilding the free lists here, we
1767 // could instead use the remove_all_pending() method on free_list to
1768 // remove only the ones that we need to remove.
1769 tear_down_region_sets(true /* free_list_only */);
1770 shrink_helper(shrink_bytes);
1771 rebuild_region_sets(true /* free_list_only */);
1772
1773 _hrm.verify_optional();
1774 verify_region_sets_optional();
1775 }
1776
1777 // Public methods.
1778
1779 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1780 CollectedHeap(),
1781 _g1_policy(policy_),
1782 _dirty_card_queue_set(false),
1783 _is_alive_closure_cm(this),
1784 _is_alive_closure_stw(this),
1785 _ref_processor_cm(NULL),
1786 _ref_processor_stw(NULL),
1787 _bot_shared(NULL),
1788 _cg1r(NULL),
1789 _g1mm(NULL),
1790 _refine_cte_cl(NULL),
1791 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1792 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1793 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1794 _humongous_reclaim_candidates(),
1795 _has_humongous_reclaim_candidates(false),
1796 _archive_allocator(NULL),
1797 _free_regions_coming(false),
1798 _young_list(new YoungList(this)),
1799 _gc_time_stamp(0),
1800 _summary_bytes_used(0),
1801 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1802 _old_evac_stats(OldPLABSize, PLABWeight),
1803 _expand_heap_after_alloc_failure(true),
1804 _old_marking_cycles_started(0),
1805 _old_marking_cycles_completed(0),
1806 _heap_summary_sent(false),
1807 _in_cset_fast_test(),
1808 _dirty_cards_region_list(NULL),
1809 _worker_cset_start_region(NULL),
1810 _worker_cset_start_region_time_stamp(NULL),
1811 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1812 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1813 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1814 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1815
1816 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1817 /* are_GC_task_threads */true,
1818 /* are_ConcurrentGC_threads */false);
1819 _workers->initialize_workers();
1820
1821 _allocator = G1Allocator::create_allocator(this);
1822 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1823
1824 // Override the default _filler_array_max_size so that no humongous filler
1825 // objects are created.
1826 _filler_array_max_size = _humongous_object_threshold_in_words;
1827
1828 uint n_queues = ParallelGCThreads;
1829 _task_queues = new RefToScanQueueSet(n_queues);
1830
1831 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1832 assert(n_rem_sets > 0, "Invariant.");
1833
1834 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1835 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1836 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1837
1838 for (uint i = 0; i < n_queues; i++) {
1839 RefToScanQueue* q = new RefToScanQueue();
1840 q->initialize();
1841 _task_queues->register_queue(i, q);
1842 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1843 }
1844 clear_cset_start_regions();
1845
1846 // Initialize the G1EvacuationFailureALot counters and flags.
1847 NOT_PRODUCT(reset_evacuation_should_fail();)
1848
1849 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1850 }
1851
1852 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1853 size_t size,
1854 size_t translation_factor) {
1855 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1856 // Allocate a new reserved space, preferring to use large pages.
1857 ReservedSpace rs(size, preferred_page_size);
1858 G1RegionToSpaceMapper* result =
1859 G1RegionToSpaceMapper::create_mapper(rs,
1860 size,
1861 rs.alignment(),
1862 HeapRegion::GrainBytes,
1863 translation_factor,
1864 mtGC);
1865 if (TracePageSizes) {
1866 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1867 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1868 }
1869 return result;
1870 }
1871
1872 jint G1CollectedHeap::initialize() {
1873 CollectedHeap::pre_initialize();
1874 os::enable_vtime();
1875
1876 G1Log::init();
1877
1878 // Necessary to satisfy locking discipline assertions.
1879
1880 MutexLocker x(Heap_lock);
1881
1882 // We have to initialize the printer before committing the heap, as
1883 // it will be used then.
1884 _hr_printer.set_active(G1PrintHeapRegions);
1885
1886 // While there are no constraints in the GC code that HeapWordSize
1887 // be any particular value, there are multiple other areas in the
1888 // system which believe this to be true (e.g. oop->object_size in some
1889 // cases incorrectly returns the size in wordSize units rather than
1890 // HeapWordSize).
1891 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1892
1893 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1894 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1895 size_t heap_alignment = collector_policy()->heap_alignment();
1896
1897 // Ensure that the sizes are properly aligned.
1898 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1899 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1900 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1901
1902 _refine_cte_cl = new RefineCardTableEntryClosure();
1903
1904 jint ecode = JNI_OK;
1905 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1906 if (_cg1r == NULL) {
1907 return ecode;
1908 }
1909
1910 // Reserve the maximum.
1911
1912 // When compressed oops are enabled, the preferred heap base
1913 // is calculated by subtracting the requested size from the
1914 // 32Gb boundary and using the result as the base address for
1915 // heap reservation. If the requested size is not aligned to
1916 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1917 // into the ReservedHeapSpace constructor) then the actual
1918 // base of the reserved heap may end up differing from the
1919 // address that was requested (i.e. the preferred heap base).
1920 // If this happens then we could end up using a non-optimal
1921 // compressed oops mode.
1922
1923 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1924 heap_alignment);
1925
1926 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1927
1928 // Create the barrier set for the entire reserved region.
1929 G1SATBCardTableLoggingModRefBS* bs
1930 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1931 bs->initialize();
1932 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1933 set_barrier_set(bs);
1934
1935 // Also create a G1 rem set.
1936 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1937
1938 // Carve out the G1 part of the heap.
1939
1940 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1941 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1942 G1RegionToSpaceMapper* heap_storage =
1943 G1RegionToSpaceMapper::create_mapper(g1_rs,
1944 g1_rs.size(),
1945 page_size,
1946 HeapRegion::GrainBytes,
1947 1,
1948 mtJavaHeap);
1949 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1950 max_byte_size, page_size,
1951 heap_rs.base(),
1952 heap_rs.size());
1953 heap_storage->set_mapping_changed_listener(&_listener);
1954
1955 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1956 G1RegionToSpaceMapper* bot_storage =
1957 create_aux_memory_mapper("Block offset table",
1958 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1959 G1BlockOffsetSharedArray::heap_map_factor());
1960
1961 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1962 G1RegionToSpaceMapper* cardtable_storage =
1963 create_aux_memory_mapper("Card table",
1964 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1965 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1966
1967 G1RegionToSpaceMapper* card_counts_storage =
1968 create_aux_memory_mapper("Card counts table",
1969 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1970 G1CardCounts::heap_map_factor());
1971
1972 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1973 G1RegionToSpaceMapper* prev_bitmap_storage =
1974 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1975 G1RegionToSpaceMapper* next_bitmap_storage =
1976 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1977
1978 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1979 g1_barrier_set()->initialize(cardtable_storage);
1980 // Do later initialization work for concurrent refinement.
1981 _cg1r->init(card_counts_storage);
1982
1983 // 6843694 - ensure that the maximum region index can fit
1984 // in the remembered set structures.
1985 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1986 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1987
1988 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1989 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1990 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1991 "too many cards per region");
1992
1993 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1994
1995 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1996
1997 {
1998 HeapWord* start = _hrm.reserved().start();
1999 HeapWord* end = _hrm.reserved().end();
2000 size_t granularity = HeapRegion::GrainBytes;
2001
2002 _in_cset_fast_test.initialize(start, end, granularity);
2003 _humongous_reclaim_candidates.initialize(start, end, granularity);
2004 }
2005
2006 // Create the ConcurrentMark data structure and thread.
2007 // (Must do this late, so that "max_regions" is defined.)
2008 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2009 if (_cm == NULL || !_cm->completed_initialization()) {
2010 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2011 return JNI_ENOMEM;
2012 }
2013 _cmThread = _cm->cmThread();
2014
2015 // Initialize the from_card cache structure of HeapRegionRemSet.
2016 HeapRegionRemSet::init_heap(max_regions());
2017
2018 // Now expand into the initial heap size.
2019 if (!expand(init_byte_size)) {
2020 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2021 return JNI_ENOMEM;
2022 }
2023
2024 // Perform any initialization actions delegated to the policy.
2025 g1_policy()->init();
2026
2027 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2028 SATB_Q_FL_lock,
2029 G1SATBProcessCompletedThreshold,
2030 Shared_SATB_Q_lock);
2031
2032 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2033 DirtyCardQ_CBL_mon,
2034 DirtyCardQ_FL_lock,
2035 concurrent_g1_refine()->yellow_zone(),
2036 concurrent_g1_refine()->red_zone(),
2037 Shared_DirtyCardQ_lock);
2038
2039 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2040 DirtyCardQ_CBL_mon,
2041 DirtyCardQ_FL_lock,
2042 -1, // never trigger processing
2043 -1, // no limit on length
2044 Shared_DirtyCardQ_lock,
2045 &JavaThread::dirty_card_queue_set());
2046
2047 // Here we allocate the dummy HeapRegion that is required by the
2048 // G1AllocRegion class.
2049 HeapRegion* dummy_region = _hrm.get_dummy_region();
2050
2051 // We'll re-use the same region whether the alloc region will
2052 // require BOT updates or not and, if it doesn't, then a non-young
2053 // region will complain that it cannot support allocations without
2054 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2055 dummy_region->set_eden();
2056 // Make sure it's full.
2057 dummy_region->set_top(dummy_region->end());
2058 G1AllocRegion::setup(this, dummy_region);
2059
2060 _allocator->init_mutator_alloc_region();
2061
2062 // Do create of the monitoring and management support so that
2063 // values in the heap have been properly initialized.
2064 _g1mm = new G1MonitoringSupport(this);
2065
2066 G1StringDedup::initialize();
2067
2068 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2069 for (uint i = 0; i < ParallelGCThreads; i++) {
2070 new (&_preserved_objs[i]) OopAndMarkOopStack();
2071 }
2072
2073 return JNI_OK;
2074 }
2075
2076 void G1CollectedHeap::stop() {
2077 // Stop all concurrent threads. We do this to make sure these threads
2078 // do not continue to execute and access resources (e.g. gclog_or_tty)
2079 // that are destroyed during shutdown.
2080 _cg1r->stop();
2081 _cmThread->stop();
2082 if (G1StringDedup::is_enabled()) {
2083 G1StringDedup::stop();
2084 }
2085 }
2086
2087 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2088 return HeapRegion::max_region_size();
2089 }
2090
2091 void G1CollectedHeap::post_initialize() {
2092 CollectedHeap::post_initialize();
2093 ref_processing_init();
2094 }
2095
2096 void G1CollectedHeap::ref_processing_init() {
2097 // Reference processing in G1 currently works as follows:
2098 //
2099 // * There are two reference processor instances. One is
2100 // used to record and process discovered references
2101 // during concurrent marking; the other is used to
2102 // record and process references during STW pauses
2103 // (both full and incremental).
2104 // * Both ref processors need to 'span' the entire heap as
2105 // the regions in the collection set may be dotted around.
2106 //
2107 // * For the concurrent marking ref processor:
2108 // * Reference discovery is enabled at initial marking.
2109 // * Reference discovery is disabled and the discovered
2110 // references processed etc during remarking.
2111 // * Reference discovery is MT (see below).
2112 // * Reference discovery requires a barrier (see below).
2113 // * Reference processing may or may not be MT
2114 // (depending on the value of ParallelRefProcEnabled
2115 // and ParallelGCThreads).
2116 // * A full GC disables reference discovery by the CM
2117 // ref processor and abandons any entries on it's
2118 // discovered lists.
2119 //
2120 // * For the STW processor:
2121 // * Non MT discovery is enabled at the start of a full GC.
2122 // * Processing and enqueueing during a full GC is non-MT.
2123 // * During a full GC, references are processed after marking.
2124 //
2125 // * Discovery (may or may not be MT) is enabled at the start
2126 // of an incremental evacuation pause.
2127 // * References are processed near the end of a STW evacuation pause.
2128 // * For both types of GC:
2129 // * Discovery is atomic - i.e. not concurrent.
2130 // * Reference discovery will not need a barrier.
2131
2132 MemRegion mr = reserved_region();
2133
2134 // Concurrent Mark ref processor
2135 _ref_processor_cm =
2136 new ReferenceProcessor(mr, // span
2137 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2138 // mt processing
2139 ParallelGCThreads,
2140 // degree of mt processing
2141 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2142 // mt discovery
2143 MAX2(ParallelGCThreads, ConcGCThreads),
2144 // degree of mt discovery
2145 false,
2146 // Reference discovery is not atomic
2147 &_is_alive_closure_cm);
2148 // is alive closure
2149 // (for efficiency/performance)
2150
2151 // STW ref processor
2152 _ref_processor_stw =
2153 new ReferenceProcessor(mr, // span
2154 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2155 // mt processing
2156 ParallelGCThreads,
2157 // degree of mt processing
2158 (ParallelGCThreads > 1),
2159 // mt discovery
2160 ParallelGCThreads,
2161 // degree of mt discovery
2162 true,
2163 // Reference discovery is atomic
2164 &_is_alive_closure_stw);
2165 // is alive closure
2166 // (for efficiency/performance)
2167 }
2168
2169 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2170 return g1_policy();
2171 }
2172
2173 size_t G1CollectedHeap::capacity() const {
2174 return _hrm.length() * HeapRegion::GrainBytes;
2175 }
2176
2177 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2178 hr->reset_gc_time_stamp();
2179 }
2180
2181 #ifndef PRODUCT
2182
2183 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2184 private:
2185 unsigned _gc_time_stamp;
2186 bool _failures;
2187
2188 public:
2189 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2190 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2191
2192 virtual bool doHeapRegion(HeapRegion* hr) {
2193 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2194 if (_gc_time_stamp != region_gc_time_stamp) {
2195 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2196 "expected %d", HR_FORMAT_PARAMS(hr),
2197 region_gc_time_stamp, _gc_time_stamp);
2198 _failures = true;
2199 }
2200 return false;
2201 }
2202
2203 bool failures() { return _failures; }
2204 };
2205
2206 void G1CollectedHeap::check_gc_time_stamps() {
2207 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2208 heap_region_iterate(&cl);
2209 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2210 }
2211 #endif // PRODUCT
2212
2213 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2214 _cg1r->hot_card_cache()->drain(cl, worker_i);
2215 }
2216
2217 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2218 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2219 size_t n_completed_buffers = 0;
2220 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2221 n_completed_buffers++;
2222 }
2223 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2224 dcqs.clear_n_completed_buffers();
2225 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2226 }
2227
2228 // Computes the sum of the storage used by the various regions.
2229 size_t G1CollectedHeap::used() const {
2230 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2231 if (_archive_allocator != NULL) {
2232 result += _archive_allocator->used();
2233 }
2234 return result;
2235 }
2236
2237 size_t G1CollectedHeap::used_unlocked() const {
2238 return _summary_bytes_used;
2239 }
2240
2241 class SumUsedClosure: public HeapRegionClosure {
2242 size_t _used;
2243 public:
2244 SumUsedClosure() : _used(0) {}
2245 bool doHeapRegion(HeapRegion* r) {
2246 _used += r->used();
2247 return false;
2248 }
2249 size_t result() { return _used; }
2250 };
2251
2252 size_t G1CollectedHeap::recalculate_used() const {
2253 double recalculate_used_start = os::elapsedTime();
2254
2255 SumUsedClosure blk;
2256 heap_region_iterate(&blk);
2257
2258 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2259 return blk.result();
2260 }
2261
2262 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2263 switch (cause) {
2264 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2265 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2266 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2267 case GCCause::_g1_humongous_allocation: return true;
2268 case GCCause::_update_allocation_context_stats_inc: return true;
2269 case GCCause::_wb_conc_mark: return true;
2270 default: return false;
2271 }
2272 }
2273
2274 #ifndef PRODUCT
2275 void G1CollectedHeap::allocate_dummy_regions() {
2276 // Let's fill up most of the region
2277 size_t word_size = HeapRegion::GrainWords - 1024;
2278 // And as a result the region we'll allocate will be humongous.
2279 guarantee(is_humongous(word_size), "sanity");
2280
2281 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2282 // Let's use the existing mechanism for the allocation
2283 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2284 AllocationContext::system());
2285 if (dummy_obj != NULL) {
2286 MemRegion mr(dummy_obj, word_size);
2287 CollectedHeap::fill_with_object(mr);
2288 } else {
2289 // If we can't allocate once, we probably cannot allocate
2290 // again. Let's get out of the loop.
2291 break;
2292 }
2293 }
2294 }
2295 #endif // !PRODUCT
2296
2297 void G1CollectedHeap::increment_old_marking_cycles_started() {
2298 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2299 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2300 "Wrong marking cycle count (started: %d, completed: %d)",
2301 _old_marking_cycles_started, _old_marking_cycles_completed);
2302
2303 _old_marking_cycles_started++;
2304 }
2305
2306 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2307 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2308
2309 // We assume that if concurrent == true, then the caller is a
2310 // concurrent thread that was joined the Suspendible Thread
2311 // Set. If there's ever a cheap way to check this, we should add an
2312 // assert here.
2313
2314 // Given that this method is called at the end of a Full GC or of a
2315 // concurrent cycle, and those can be nested (i.e., a Full GC can
2316 // interrupt a concurrent cycle), the number of full collections
2317 // completed should be either one (in the case where there was no
2318 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2319 // behind the number of full collections started.
2320
2321 // This is the case for the inner caller, i.e. a Full GC.
2322 assert(concurrent ||
2323 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2324 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2325 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2326 "is inconsistent with _old_marking_cycles_completed = %u",
2327 _old_marking_cycles_started, _old_marking_cycles_completed);
2328
2329 // This is the case for the outer caller, i.e. the concurrent cycle.
2330 assert(!concurrent ||
2331 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2332 "for outer caller (concurrent cycle): "
2333 "_old_marking_cycles_started = %u "
2334 "is inconsistent with _old_marking_cycles_completed = %u",
2335 _old_marking_cycles_started, _old_marking_cycles_completed);
2336
2337 _old_marking_cycles_completed += 1;
2338
2339 // We need to clear the "in_progress" flag in the CM thread before
2340 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2341 // is set) so that if a waiter requests another System.gc() it doesn't
2342 // incorrectly see that a marking cycle is still in progress.
2343 if (concurrent) {
2344 _cmThread->set_idle();
2345 }
2346
2347 // This notify_all() will ensure that a thread that called
2348 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2349 // and it's waiting for a full GC to finish will be woken up. It is
2350 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2351 FullGCCount_lock->notify_all();
2352 }
2353
2354 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2355 GCIdMarkAndRestore conc_gc_id_mark;
2356 collector_state()->set_concurrent_cycle_started(true);
2357 _gc_timer_cm->register_gc_start(start_time);
2358
2359 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2360 trace_heap_before_gc(_gc_tracer_cm);
2361 _cmThread->set_gc_id(GCId::current());
2362 }
2363
2364 void G1CollectedHeap::register_concurrent_cycle_end() {
2365 if (collector_state()->concurrent_cycle_started()) {
2366 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2367 if (_cm->has_aborted()) {
2368 _gc_tracer_cm->report_concurrent_mode_failure();
2369 }
2370
2371 _gc_timer_cm->register_gc_end();
2372 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2373
2374 // Clear state variables to prepare for the next concurrent cycle.
2375 collector_state()->set_concurrent_cycle_started(false);
2376 _heap_summary_sent = false;
2377 }
2378 }
2379
2380 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2381 if (collector_state()->concurrent_cycle_started()) {
2382 // This function can be called when:
2383 // the cleanup pause is run
2384 // the concurrent cycle is aborted before the cleanup pause.
2385 // the concurrent cycle is aborted after the cleanup pause,
2386 // but before the concurrent cycle end has been registered.
2387 // Make sure that we only send the heap information once.
2388 if (!_heap_summary_sent) {
2389 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2390 trace_heap_after_gc(_gc_tracer_cm);
2391 _heap_summary_sent = true;
2392 }
2393 }
2394 }
2395
2396 void G1CollectedHeap::collect(GCCause::Cause cause) {
2397 assert_heap_not_locked();
2398
2399 uint gc_count_before;
2400 uint old_marking_count_before;
2401 uint full_gc_count_before;
2402 bool retry_gc;
2403
2404 do {
2405 retry_gc = false;
2406
2407 {
2408 MutexLocker ml(Heap_lock);
2409
2410 // Read the GC count while holding the Heap_lock
2411 gc_count_before = total_collections();
2412 full_gc_count_before = total_full_collections();
2413 old_marking_count_before = _old_marking_cycles_started;
2414 }
2415
2416 if (should_do_concurrent_full_gc(cause)) {
2417 // Schedule an initial-mark evacuation pause that will start a
2418 // concurrent cycle. We're setting word_size to 0 which means that
2419 // we are not requesting a post-GC allocation.
2420 VM_G1IncCollectionPause op(gc_count_before,
2421 0, /* word_size */
2422 true, /* should_initiate_conc_mark */
2423 g1_policy()->max_pause_time_ms(),
2424 cause);
2425 op.set_allocation_context(AllocationContext::current());
2426
2427 VMThread::execute(&op);
2428 if (!op.pause_succeeded()) {
2429 if (old_marking_count_before == _old_marking_cycles_started) {
2430 retry_gc = op.should_retry_gc();
2431 } else {
2432 // A Full GC happened while we were trying to schedule the
2433 // initial-mark GC. No point in starting a new cycle given
2434 // that the whole heap was collected anyway.
2435 }
2436
2437 if (retry_gc) {
2438 if (GC_locker::is_active_and_needs_gc()) {
2439 GC_locker::stall_until_clear();
2440 }
2441 }
2442 }
2443 } else {
2444 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2445 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2446
2447 // Schedule a standard evacuation pause. We're setting word_size
2448 // to 0 which means that we are not requesting a post-GC allocation.
2449 VM_G1IncCollectionPause op(gc_count_before,
2450 0, /* word_size */
2451 false, /* should_initiate_conc_mark */
2452 g1_policy()->max_pause_time_ms(),
2453 cause);
2454 VMThread::execute(&op);
2455 } else {
2456 // Schedule a Full GC.
2457 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2458 VMThread::execute(&op);
2459 }
2460 }
2461 } while (retry_gc);
2462 }
2463
2464 bool G1CollectedHeap::is_in(const void* p) const {
2465 if (_hrm.reserved().contains(p)) {
2466 // Given that we know that p is in the reserved space,
2467 // heap_region_containing() should successfully
2468 // return the containing region.
2469 HeapRegion* hr = heap_region_containing(p);
2470 return hr->is_in(p);
2471 } else {
2472 return false;
2473 }
2474 }
2475
2476 #ifdef ASSERT
2477 bool G1CollectedHeap::is_in_exact(const void* p) const {
2478 bool contains = reserved_region().contains(p);
2479 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2480 if (contains && available) {
2481 return true;
2482 } else {
2483 return false;
2484 }
2485 }
2486 #endif
2487
2488 bool G1CollectedHeap::obj_in_cs(oop obj) {
2489 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2490 return r != NULL && r->in_collection_set();
2491 }
2492
2493 // Iteration functions.
2494
2495 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2496
2497 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2498 ExtendedOopClosure* _cl;
2499 public:
2500 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2501 bool doHeapRegion(HeapRegion* r) {
2502 if (!r->is_continues_humongous()) {
2503 r->oop_iterate(_cl);
2504 }
2505 return false;
2506 }
2507 };
2508
2509 // Iterates an ObjectClosure over all objects within a HeapRegion.
2510
2511 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2512 ObjectClosure* _cl;
2513 public:
2514 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2515 bool doHeapRegion(HeapRegion* r) {
2516 if (!r->is_continues_humongous()) {
2517 r->object_iterate(_cl);
2518 }
2519 return false;
2520 }
2521 };
2522
2523 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2524 IterateObjectClosureRegionClosure blk(cl);
2525 heap_region_iterate(&blk);
2526 }
2527
2528 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2529 _hrm.iterate(cl);
2530 }
2531
2532 void
2533 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2534 uint worker_id,
2535 HeapRegionClaimer *hrclaimer,
2536 bool concurrent) const {
2537 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2538 }
2539
2540 // Clear the cached CSet starting regions and (more importantly)
2541 // the time stamps. Called when we reset the GC time stamp.
2542 void G1CollectedHeap::clear_cset_start_regions() {
2543 assert(_worker_cset_start_region != NULL, "sanity");
2544 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2545
2546 for (uint i = 0; i < ParallelGCThreads; i++) {
2547 _worker_cset_start_region[i] = NULL;
2548 _worker_cset_start_region_time_stamp[i] = 0;
2549 }
2550 }
2551
2552 // Given the id of a worker, obtain or calculate a suitable
2553 // starting region for iterating over the current collection set.
2554 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2555 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2556
2557 HeapRegion* result = NULL;
2558 unsigned gc_time_stamp = get_gc_time_stamp();
2559
2560 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2561 // Cached starting region for current worker was set
2562 // during the current pause - so it's valid.
2563 // Note: the cached starting heap region may be NULL
2564 // (when the collection set is empty).
2565 result = _worker_cset_start_region[worker_i];
2566 assert(result == NULL || result->in_collection_set(), "sanity");
2567 return result;
2568 }
2569
2570 // The cached entry was not valid so let's calculate
2571 // a suitable starting heap region for this worker.
2572
2573 // We want the parallel threads to start their collection
2574 // set iteration at different collection set regions to
2575 // avoid contention.
2576 // If we have:
2577 // n collection set regions
2578 // p threads
2579 // Then thread t will start at region floor ((t * n) / p)
2580
2581 result = g1_policy()->collection_set();
2582 uint cs_size = g1_policy()->cset_region_length();
2583 uint active_workers = workers()->active_workers();
2584
2585 uint end_ind = (cs_size * worker_i) / active_workers;
2586 uint start_ind = 0;
2587
2588 if (worker_i > 0 &&
2589 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2590 // Previous workers starting region is valid
2591 // so let's iterate from there
2592 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2593 result = _worker_cset_start_region[worker_i - 1];
2594 }
2595
2596 for (uint i = start_ind; i < end_ind; i++) {
2597 result = result->next_in_collection_set();
2598 }
2599
2600 // Note: the calculated starting heap region may be NULL
2601 // (when the collection set is empty).
2602 assert(result == NULL || result->in_collection_set(), "sanity");
2603 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2604 "should be updated only once per pause");
2605 _worker_cset_start_region[worker_i] = result;
2606 OrderAccess::storestore();
2607 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2608 return result;
2609 }
2610
2611 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2612 HeapRegion* r = g1_policy()->collection_set();
2613 while (r != NULL) {
2614 HeapRegion* next = r->next_in_collection_set();
2615 if (cl->doHeapRegion(r)) {
2616 cl->incomplete();
2617 return;
2618 }
2619 r = next;
2620 }
2621 }
2622
2623 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2624 HeapRegionClosure *cl) {
2625 if (r == NULL) {
2626 // The CSet is empty so there's nothing to do.
2627 return;
2628 }
2629
2630 assert(r->in_collection_set(),
2631 "Start region must be a member of the collection set.");
2632 HeapRegion* cur = r;
2633 while (cur != NULL) {
2634 HeapRegion* next = cur->next_in_collection_set();
2635 if (cl->doHeapRegion(cur) && false) {
2636 cl->incomplete();
2637 return;
2638 }
2639 cur = next;
2640 }
2641 cur = g1_policy()->collection_set();
2642 while (cur != r) {
2643 HeapRegion* next = cur->next_in_collection_set();
2644 if (cl->doHeapRegion(cur) && false) {
2645 cl->incomplete();
2646 return;
2647 }
2648 cur = next;
2649 }
2650 }
2651
2652 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2653 HeapRegion* result = _hrm.next_region_in_heap(from);
2654 while (result != NULL && result->is_pinned()) {
2655 result = _hrm.next_region_in_heap(result);
2656 }
2657 return result;
2658 }
2659
2660 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2661 HeapRegion* hr = heap_region_containing(addr);
2662 return hr->block_start(addr);
2663 }
2664
2665 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2666 HeapRegion* hr = heap_region_containing(addr);
2667 return hr->block_size(addr);
2668 }
2669
2670 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2671 HeapRegion* hr = heap_region_containing(addr);
2672 return hr->block_is_obj(addr);
2673 }
2674
2675 bool G1CollectedHeap::supports_tlab_allocation() const {
2676 return true;
2677 }
2678
2679 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2680 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2681 }
2682
2683 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2684 return young_list()->eden_used_bytes();
2685 }
2686
2687 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2688 // must be equal to the humongous object limit.
2689 size_t G1CollectedHeap::max_tlab_size() const {
2690 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2691 }
2692
2693 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2694 AllocationContext_t context = AllocationContext::current();
2695 return _allocator->unsafe_max_tlab_alloc(context);
2696 }
2697
2698 size_t G1CollectedHeap::max_capacity() const {
2699 return _hrm.reserved().byte_size();
2700 }
2701
2702 jlong G1CollectedHeap::millis_since_last_gc() {
2703 // assert(false, "NYI");
2704 return 0;
2705 }
2706
2707 void G1CollectedHeap::prepare_for_verify() {
2708 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2709 ensure_parsability(false);
2710 }
2711 g1_rem_set()->prepare_for_verify();
2712 }
2713
2714 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2715 VerifyOption vo) {
2716 switch (vo) {
2717 case VerifyOption_G1UsePrevMarking:
2718 return hr->obj_allocated_since_prev_marking(obj);
2719 case VerifyOption_G1UseNextMarking:
2720 return hr->obj_allocated_since_next_marking(obj);
2721 case VerifyOption_G1UseMarkWord:
2722 return false;
2723 default:
2724 ShouldNotReachHere();
2725 }
2726 return false; // keep some compilers happy
2727 }
2728
2729 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2730 switch (vo) {
2731 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2732 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2733 case VerifyOption_G1UseMarkWord: return NULL;
2734 default: ShouldNotReachHere();
2735 }
2736 return NULL; // keep some compilers happy
2737 }
2738
2739 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2740 switch (vo) {
2741 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2742 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2743 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2744 default: ShouldNotReachHere();
2745 }
2746 return false; // keep some compilers happy
2747 }
2748
2749 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2750 switch (vo) {
2751 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2752 case VerifyOption_G1UseNextMarking: return "NTAMS";
2753 case VerifyOption_G1UseMarkWord: return "NONE";
2754 default: ShouldNotReachHere();
2755 }
2756 return NULL; // keep some compilers happy
2757 }
2758
2759 class VerifyRootsClosure: public OopClosure {
2760 private:
2761 G1CollectedHeap* _g1h;
2762 VerifyOption _vo;
2763 bool _failures;
2764 public:
2765 // _vo == UsePrevMarking -> use "prev" marking information,
2766 // _vo == UseNextMarking -> use "next" marking information,
2767 // _vo == UseMarkWord -> use mark word from object header.
2768 VerifyRootsClosure(VerifyOption vo) :
2769 _g1h(G1CollectedHeap::heap()),
2770 _vo(vo),
2771 _failures(false) { }
2772
2773 bool failures() { return _failures; }
2774
2775 template <class T> void do_oop_nv(T* p) {
2776 T heap_oop = oopDesc::load_heap_oop(p);
2777 if (!oopDesc::is_null(heap_oop)) {
2778 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2779 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2780 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2781 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2782 if (_vo == VerifyOption_G1UseMarkWord) {
2783 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2784 }
2785 obj->print_on(gclog_or_tty);
2786 _failures = true;
2787 }
2788 }
2789 }
2790
2791 void do_oop(oop* p) { do_oop_nv(p); }
2792 void do_oop(narrowOop* p) { do_oop_nv(p); }
2793 };
2794
2795 class G1VerifyCodeRootOopClosure: public OopClosure {
2796 G1CollectedHeap* _g1h;
2797 OopClosure* _root_cl;
2798 nmethod* _nm;
2799 VerifyOption _vo;
2800 bool _failures;
2801
2802 template <class T> void do_oop_work(T* p) {
2803 // First verify that this root is live
2804 _root_cl->do_oop(p);
2805
2806 if (!G1VerifyHeapRegionCodeRoots) {
2807 // We're not verifying the code roots attached to heap region.
2808 return;
2809 }
2810
2811 // Don't check the code roots during marking verification in a full GC
2812 if (_vo == VerifyOption_G1UseMarkWord) {
2813 return;
2814 }
2815
2816 // Now verify that the current nmethod (which contains p) is
2817 // in the code root list of the heap region containing the
2818 // object referenced by p.
2819
2820 T heap_oop = oopDesc::load_heap_oop(p);
2821 if (!oopDesc::is_null(heap_oop)) {
2822 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2823
2824 // Now fetch the region containing the object
2825 HeapRegion* hr = _g1h->heap_region_containing(obj);
2826 HeapRegionRemSet* hrrs = hr->rem_set();
2827 // Verify that the strong code root list for this region
2828 // contains the nmethod
2829 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2830 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2831 "from nmethod " PTR_FORMAT " not in strong "
2832 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2833 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2834 _failures = true;
2835 }
2836 }
2837 }
2838
2839 public:
2840 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2841 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2842
2843 void do_oop(oop* p) { do_oop_work(p); }
2844 void do_oop(narrowOop* p) { do_oop_work(p); }
2845
2846 void set_nmethod(nmethod* nm) { _nm = nm; }
2847 bool failures() { return _failures; }
2848 };
2849
2850 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2851 G1VerifyCodeRootOopClosure* _oop_cl;
2852
2853 public:
2854 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2855 _oop_cl(oop_cl) {}
2856
2857 void do_code_blob(CodeBlob* cb) {
2858 nmethod* nm = cb->as_nmethod_or_null();
2859 if (nm != NULL) {
2860 _oop_cl->set_nmethod(nm);
2861 nm->oops_do(_oop_cl);
2862 }
2863 }
2864 };
2865
2866 class YoungRefCounterClosure : public OopClosure {
2867 G1CollectedHeap* _g1h;
2868 int _count;
2869 public:
2870 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2871 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2872 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2873
2874 int count() { return _count; }
2875 void reset_count() { _count = 0; };
2876 };
2877
2878 class VerifyKlassClosure: public KlassClosure {
2879 YoungRefCounterClosure _young_ref_counter_closure;
2880 OopClosure *_oop_closure;
2881 public:
2882 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2883 void do_klass(Klass* k) {
2884 k->oops_do(_oop_closure);
2885
2886 _young_ref_counter_closure.reset_count();
2887 k->oops_do(&_young_ref_counter_closure);
2888 if (_young_ref_counter_closure.count() > 0) {
2889 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2890 }
2891 }
2892 };
2893
2894 class VerifyLivenessOopClosure: public OopClosure {
2895 G1CollectedHeap* _g1h;
2896 VerifyOption _vo;
2897 public:
2898 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2899 _g1h(g1h), _vo(vo)
2900 { }
2901 void do_oop(narrowOop *p) { do_oop_work(p); }
2902 void do_oop( oop *p) { do_oop_work(p); }
2903
2904 template <class T> void do_oop_work(T *p) {
2905 oop obj = oopDesc::load_decode_heap_oop(p);
2906 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2907 "Dead object referenced by a not dead object");
2908 }
2909 };
2910
2911 class VerifyObjsInRegionClosure: public ObjectClosure {
2912 private:
2913 G1CollectedHeap* _g1h;
2914 size_t _live_bytes;
2915 HeapRegion *_hr;
2916 VerifyOption _vo;
2917 public:
2918 // _vo == UsePrevMarking -> use "prev" marking information,
2919 // _vo == UseNextMarking -> use "next" marking information,
2920 // _vo == UseMarkWord -> use mark word from object header.
2921 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2922 : _live_bytes(0), _hr(hr), _vo(vo) {
2923 _g1h = G1CollectedHeap::heap();
2924 }
2925 void do_object(oop o) {
2926 VerifyLivenessOopClosure isLive(_g1h, _vo);
2927 assert(o != NULL, "Huh?");
2928 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2929 // If the object is alive according to the mark word,
2930 // then verify that the marking information agrees.
2931 // Note we can't verify the contra-positive of the
2932 // above: if the object is dead (according to the mark
2933 // word), it may not be marked, or may have been marked
2934 // but has since became dead, or may have been allocated
2935 // since the last marking.
2936 if (_vo == VerifyOption_G1UseMarkWord) {
2937 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2938 }
2939
2940 o->oop_iterate_no_header(&isLive);
2941 if (!_hr->obj_allocated_since_prev_marking(o)) {
2942 size_t obj_size = o->size(); // Make sure we don't overflow
2943 _live_bytes += (obj_size * HeapWordSize);
2944 }
2945 }
2946 }
2947 size_t live_bytes() { return _live_bytes; }
2948 };
2949
2950 class VerifyArchiveOopClosure: public OopClosure {
2951 public:
2952 VerifyArchiveOopClosure(HeapRegion *hr) { }
2953 void do_oop(narrowOop *p) { do_oop_work(p); }
2954 void do_oop( oop *p) { do_oop_work(p); }
2955
2956 template <class T> void do_oop_work(T *p) {
2957 oop obj = oopDesc::load_decode_heap_oop(p);
2958 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2959 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2960 p2i(p), p2i(obj));
2961 }
2962 };
2963
2964 class VerifyArchiveRegionClosure: public ObjectClosure {
2965 public:
2966 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2967 // Verify that all object pointers are to archive regions.
2968 void do_object(oop o) {
2969 VerifyArchiveOopClosure checkOop(NULL);
2970 assert(o != NULL, "Should not be here for NULL oops");
2971 o->oop_iterate_no_header(&checkOop);
2972 }
2973 };
2974
2975 class VerifyRegionClosure: public HeapRegionClosure {
2976 private:
2977 bool _par;
2978 VerifyOption _vo;
2979 bool _failures;
2980 public:
2981 // _vo == UsePrevMarking -> use "prev" marking information,
2982 // _vo == UseNextMarking -> use "next" marking information,
2983 // _vo == UseMarkWord -> use mark word from object header.
2984 VerifyRegionClosure(bool par, VerifyOption vo)
2985 : _par(par),
2986 _vo(vo),
2987 _failures(false) {}
2988
2989 bool failures() {
2990 return _failures;
2991 }
2992
2993 bool doHeapRegion(HeapRegion* r) {
2994 // For archive regions, verify there are no heap pointers to
2995 // non-pinned regions. For all others, verify liveness info.
2996 if (r->is_archive()) {
2997 VerifyArchiveRegionClosure verify_oop_pointers(r);
2998 r->object_iterate(&verify_oop_pointers);
2999 return true;
3000 }
3001 if (!r->is_continues_humongous()) {
3002 bool failures = false;
3003 r->verify(_vo, &failures);
3004 if (failures) {
3005 _failures = true;
3006 } else if (!r->is_starts_humongous()) {
3007 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3008 r->object_iterate(¬_dead_yet_cl);
3009 if (_vo != VerifyOption_G1UseNextMarking) {
3010 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3011 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3012 "max_live_bytes " SIZE_FORMAT " "
3013 "< calculated " SIZE_FORMAT,
3014 p2i(r->bottom()), p2i(r->end()),
3015 r->max_live_bytes(),
3016 not_dead_yet_cl.live_bytes());
3017 _failures = true;
3018 }
3019 } else {
3020 // When vo == UseNextMarking we cannot currently do a sanity
3021 // check on the live bytes as the calculation has not been
3022 // finalized yet.
3023 }
3024 }
3025 }
3026 return false; // stop the region iteration if we hit a failure
3027 }
3028 };
3029
3030 // This is the task used for parallel verification of the heap regions
3031
3032 class G1ParVerifyTask: public AbstractGangTask {
3033 private:
3034 G1CollectedHeap* _g1h;
3035 VerifyOption _vo;
3036 bool _failures;
3037 HeapRegionClaimer _hrclaimer;
3038
3039 public:
3040 // _vo == UsePrevMarking -> use "prev" marking information,
3041 // _vo == UseNextMarking -> use "next" marking information,
3042 // _vo == UseMarkWord -> use mark word from object header.
3043 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3044 AbstractGangTask("Parallel verify task"),
3045 _g1h(g1h),
3046 _vo(vo),
3047 _failures(false),
3048 _hrclaimer(g1h->workers()->active_workers()) {}
3049
3050 bool failures() {
3051 return _failures;
3052 }
3053
3054 void work(uint worker_id) {
3055 HandleMark hm;
3056 VerifyRegionClosure blk(true, _vo);
3057 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3058 if (blk.failures()) {
3059 _failures = true;
3060 }
3061 }
3062 };
3063
3064 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3065 if (SafepointSynchronize::is_at_safepoint()) {
3066 assert(Thread::current()->is_VM_thread(),
3067 "Expected to be executed serially by the VM thread at this point");
3068
3069 if (!silent) { gclog_or_tty->print("Roots "); }
3070 VerifyRootsClosure rootsCl(vo);
3071 VerifyKlassClosure klassCl(this, &rootsCl);
3072 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3073
3074 // We apply the relevant closures to all the oops in the
3075 // system dictionary, class loader data graph, the string table
3076 // and the nmethods in the code cache.
3077 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3078 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3079
3080 {
3081 G1RootProcessor root_processor(this, 1);
3082 root_processor.process_all_roots(&rootsCl,
3083 &cldCl,
3084 &blobsCl);
3085 }
3086
3087 bool failures = rootsCl.failures() || codeRootsCl.failures();
3088
3089 if (vo != VerifyOption_G1UseMarkWord) {
3090 // If we're verifying during a full GC then the region sets
3091 // will have been torn down at the start of the GC. Therefore
3092 // verifying the region sets will fail. So we only verify
3093 // the region sets when not in a full GC.
3094 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3095 verify_region_sets();
3096 }
3097
3098 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3099 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3100
3101 G1ParVerifyTask task(this, vo);
3102 workers()->run_task(&task);
3103 if (task.failures()) {
3104 failures = true;
3105 }
3106
3107 } else {
3108 VerifyRegionClosure blk(false, vo);
3109 heap_region_iterate(&blk);
3110 if (blk.failures()) {
3111 failures = true;
3112 }
3113 }
3114
3115 if (G1StringDedup::is_enabled()) {
3116 if (!silent) gclog_or_tty->print("StrDedup ");
3117 G1StringDedup::verify();
3118 }
3119
3120 if (failures) {
3121 gclog_or_tty->print_cr("Heap:");
3122 // It helps to have the per-region information in the output to
3123 // help us track down what went wrong. This is why we call
3124 // print_extended_on() instead of print_on().
3125 print_extended_on(gclog_or_tty);
3126 gclog_or_tty->cr();
3127 gclog_or_tty->flush();
3128 }
3129 guarantee(!failures, "there should not have been any failures");
3130 } else {
3131 if (!silent) {
3132 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3133 if (G1StringDedup::is_enabled()) {
3134 gclog_or_tty->print(", StrDedup");
3135 }
3136 gclog_or_tty->print(") ");
3137 }
3138 }
3139 }
3140
3141 void G1CollectedHeap::verify(bool silent) {
3142 verify(silent, VerifyOption_G1UsePrevMarking);
3143 }
3144
3145 double G1CollectedHeap::verify(bool guard, const char* msg) {
3146 double verify_time_ms = 0.0;
3147
3148 if (guard && total_collections() >= VerifyGCStartAt) {
3149 double verify_start = os::elapsedTime();
3150 HandleMark hm; // Discard invalid handles created during verification
3151 prepare_for_verify();
3152 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3153 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3154 }
3155
3156 return verify_time_ms;
3157 }
3158
3159 void G1CollectedHeap::verify_before_gc() {
3160 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3161 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3162 }
3163
3164 void G1CollectedHeap::verify_after_gc() {
3165 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3166 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3167 }
3168
3169 class PrintRegionClosure: public HeapRegionClosure {
3170 outputStream* _st;
3171 public:
3172 PrintRegionClosure(outputStream* st) : _st(st) {}
3173 bool doHeapRegion(HeapRegion* r) {
3174 r->print_on(_st);
3175 return false;
3176 }
3177 };
3178
3179 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3180 const HeapRegion* hr,
3181 const VerifyOption vo) const {
3182 switch (vo) {
3183 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3184 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3185 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3186 default: ShouldNotReachHere();
3187 }
3188 return false; // keep some compilers happy
3189 }
3190
3191 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3192 const VerifyOption vo) const {
3193 switch (vo) {
3194 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3195 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3196 case VerifyOption_G1UseMarkWord: {
3197 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3198 return !obj->is_gc_marked() && !hr->is_archive();
3199 }
3200 default: ShouldNotReachHere();
3201 }
3202 return false; // keep some compilers happy
3203 }
3204
3205 void G1CollectedHeap::print_on(outputStream* st) const {
3206 st->print(" %-20s", "garbage-first heap");
3207 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3208 capacity()/K, used_unlocked()/K);
3209 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3210 p2i(_hrm.reserved().start()),
3211 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3212 p2i(_hrm.reserved().end()));
3213 st->cr();
3214 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3215 uint young_regions = _young_list->length();
3216 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3217 (size_t) young_regions * HeapRegion::GrainBytes / K);
3218 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3219 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3220 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3221 st->cr();
3222 MetaspaceAux::print_on(st);
3223 }
3224
3225 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3226 print_on(st);
3227
3228 // Print the per-region information.
3229 st->cr();
3230 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3231 "HS=humongous(starts), HC=humongous(continues), "
3232 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3233 "PTAMS=previous top-at-mark-start, "
3234 "NTAMS=next top-at-mark-start)");
3235 PrintRegionClosure blk(st);
3236 heap_region_iterate(&blk);
3237 }
3238
3239 void G1CollectedHeap::print_on_error(outputStream* st) const {
3240 this->CollectedHeap::print_on_error(st);
3241
3242 if (_cm != NULL) {
3243 st->cr();
3244 _cm->print_on_error(st);
3245 }
3246 }
3247
3248 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3249 workers()->print_worker_threads_on(st);
3250 _cmThread->print_on(st);
3251 st->cr();
3252 _cm->print_worker_threads_on(st);
3253 _cg1r->print_worker_threads_on(st);
3254 if (G1StringDedup::is_enabled()) {
3255 G1StringDedup::print_worker_threads_on(st);
3256 }
3257 }
3258
3259 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3260 workers()->threads_do(tc);
3261 tc->do_thread(_cmThread);
3262 _cg1r->threads_do(tc);
3263 if (G1StringDedup::is_enabled()) {
3264 G1StringDedup::threads_do(tc);
3265 }
3266 }
3267
3268 void G1CollectedHeap::print_tracing_info() const {
3269 // We'll overload this to mean "trace GC pause statistics."
3270 if (TraceYoungGenTime || TraceOldGenTime) {
3271 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3272 // to that.
3273 g1_policy()->print_tracing_info();
3274 }
3275 if (G1SummarizeRSetStats) {
3276 g1_rem_set()->print_summary_info();
3277 }
3278 if (G1SummarizeConcMark) {
3279 concurrent_mark()->print_summary_info();
3280 }
3281 g1_policy()->print_yg_surv_rate_info();
3282 }
3283
3284 #ifndef PRODUCT
3285 // Helpful for debugging RSet issues.
3286
3287 class PrintRSetsClosure : public HeapRegionClosure {
3288 private:
3289 const char* _msg;
3290 size_t _occupied_sum;
3291
3292 public:
3293 bool doHeapRegion(HeapRegion* r) {
3294 HeapRegionRemSet* hrrs = r->rem_set();
3295 size_t occupied = hrrs->occupied();
3296 _occupied_sum += occupied;
3297
3298 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3299 HR_FORMAT_PARAMS(r));
3300 if (occupied == 0) {
3301 gclog_or_tty->print_cr(" RSet is empty");
3302 } else {
3303 hrrs->print();
3304 }
3305 gclog_or_tty->print_cr("----------");
3306 return false;
3307 }
3308
3309 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3310 gclog_or_tty->cr();
3311 gclog_or_tty->print_cr("========================================");
3312 gclog_or_tty->print_cr("%s", msg);
3313 gclog_or_tty->cr();
3314 }
3315
3316 ~PrintRSetsClosure() {
3317 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3318 gclog_or_tty->print_cr("========================================");
3319 gclog_or_tty->cr();
3320 }
3321 };
3322
3323 void G1CollectedHeap::print_cset_rsets() {
3324 PrintRSetsClosure cl("Printing CSet RSets");
3325 collection_set_iterate(&cl);
3326 }
3327
3328 void G1CollectedHeap::print_all_rsets() {
3329 PrintRSetsClosure cl("Printing All RSets");;
3330 heap_region_iterate(&cl);
3331 }
3332 #endif // PRODUCT
3333
3334 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3335 YoungList* young_list = heap()->young_list();
3336
3337 size_t eden_used_bytes = young_list->eden_used_bytes();
3338 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3339
3340 size_t eden_capacity_bytes =
3341 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3342
3343 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3344 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3345 }
3346
3347 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3348 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3349 stats->unused(), stats->used(), stats->region_end_waste(),
3350 stats->regions_filled(), stats->direct_allocated(),
3351 stats->failure_used(), stats->failure_waste());
3352 }
3353
3354 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3355 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3356 gc_tracer->report_gc_heap_summary(when, heap_summary);
3357
3358 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3359 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3360 }
3361
3362
3363 G1CollectedHeap* G1CollectedHeap::heap() {
3364 CollectedHeap* heap = Universe::heap();
3365 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3366 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3367 return (G1CollectedHeap*)heap;
3368 }
3369
3370 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3371 // always_do_update_barrier = false;
3372 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3373 // Fill TLAB's and such
3374 accumulate_statistics_all_tlabs();
3375 ensure_parsability(true);
3376
3377 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3378 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3379 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3380 }
3381 }
3382
3383 void G1CollectedHeap::gc_epilogue(bool full) {
3384
3385 if (G1SummarizeRSetStats &&
3386 (G1SummarizeRSetStatsPeriod > 0) &&
3387 // we are at the end of the GC. Total collections has already been increased.
3388 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3389 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3390 }
3391
3392 // FIXME: what is this about?
3393 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3394 // is set.
3395 #if defined(COMPILER2) || INCLUDE_JVMCI
3396 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3397 #endif
3398 // always_do_update_barrier = true;
3399
3400 resize_all_tlabs();
3401 allocation_context_stats().update(full);
3402
3403 // We have just completed a GC. Update the soft reference
3404 // policy with the new heap occupancy
3405 Universe::update_heap_info_at_gc();
3406 }
3407
3408 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3409 uint gc_count_before,
3410 bool* succeeded,
3411 GCCause::Cause gc_cause) {
3412 assert_heap_not_locked_and_not_at_safepoint();
3413 g1_policy()->record_stop_world_start();
3414 VM_G1IncCollectionPause op(gc_count_before,
3415 word_size,
3416 false, /* should_initiate_conc_mark */
3417 g1_policy()->max_pause_time_ms(),
3418 gc_cause);
3419
3420 op.set_allocation_context(AllocationContext::current());
3421 VMThread::execute(&op);
3422
3423 HeapWord* result = op.result();
3424 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3425 assert(result == NULL || ret_succeeded,
3426 "the result should be NULL if the VM did not succeed");
3427 *succeeded = ret_succeeded;
3428
3429 assert_heap_not_locked();
3430 return result;
3431 }
3432
3433 void
3434 G1CollectedHeap::doConcurrentMark() {
3435 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3436 if (!_cmThread->in_progress()) {
3437 _cmThread->set_started();
3438 CGC_lock->notify();
3439 }
3440 }
3441
3442 size_t G1CollectedHeap::pending_card_num() {
3443 size_t extra_cards = 0;
3444 JavaThread *curr = Threads::first();
3445 while (curr != NULL) {
3446 DirtyCardQueue& dcq = curr->dirty_card_queue();
3447 extra_cards += dcq.size();
3448 curr = curr->next();
3449 }
3450 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3451 size_t buffer_size = dcqs.buffer_size();
3452 size_t buffer_num = dcqs.completed_buffers_num();
3453
3454 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3455 // in bytes - not the number of 'entries'. We need to convert
3456 // into a number of cards.
3457 return (buffer_size * buffer_num + extra_cards) / oopSize;
3458 }
3459
3460 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3461 private:
3462 size_t _total_humongous;
3463 size_t _candidate_humongous;
3464
3465 DirtyCardQueue _dcq;
3466
3467 // We don't nominate objects with many remembered set entries, on
3468 // the assumption that such objects are likely still live.
3469 bool is_remset_small(HeapRegion* region) const {
3470 HeapRegionRemSet* const rset = region->rem_set();
3471 return G1EagerReclaimHumongousObjectsWithStaleRefs
3472 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3473 : rset->is_empty();
3474 }
3475
3476 bool is_typeArray_region(HeapRegion* region) const {
3477 return oop(region->bottom())->is_typeArray();
3478 }
3479
3480 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3481 assert(region->is_starts_humongous(), "Must start a humongous object");
3482
3483 // Candidate selection must satisfy the following constraints
3484 // while concurrent marking is in progress:
3485 //
3486 // * In order to maintain SATB invariants, an object must not be
3487 // reclaimed if it was allocated before the start of marking and
3488 // has not had its references scanned. Such an object must have
3489 // its references (including type metadata) scanned to ensure no
3490 // live objects are missed by the marking process. Objects
3491 // allocated after the start of concurrent marking don't need to
3492 // be scanned.
3493 //
3494 // * An object must not be reclaimed if it is on the concurrent
3495 // mark stack. Objects allocated after the start of concurrent
3496 // marking are never pushed on the mark stack.
3497 //
3498 // Nominating only objects allocated after the start of concurrent
3499 // marking is sufficient to meet both constraints. This may miss
3500 // some objects that satisfy the constraints, but the marking data
3501 // structures don't support efficiently performing the needed
3502 // additional tests or scrubbing of the mark stack.
3503 //
3504 // However, we presently only nominate is_typeArray() objects.
3505 // A humongous object containing references induces remembered
3506 // set entries on other regions. In order to reclaim such an
3507 // object, those remembered sets would need to be cleaned up.
3508 //
3509 // We also treat is_typeArray() objects specially, allowing them
3510 // to be reclaimed even if allocated before the start of
3511 // concurrent mark. For this we rely on mark stack insertion to
3512 // exclude is_typeArray() objects, preventing reclaiming an object
3513 // that is in the mark stack. We also rely on the metadata for
3514 // such objects to be built-in and so ensured to be kept live.
3515 // Frequent allocation and drop of large binary blobs is an
3516 // important use case for eager reclaim, and this special handling
3517 // may reduce needed headroom.
3518
3519 return is_typeArray_region(region) && is_remset_small(region);
3520 }
3521
3522 public:
3523 RegisterHumongousWithInCSetFastTestClosure()
3524 : _total_humongous(0),
3525 _candidate_humongous(0),
3526 _dcq(&JavaThread::dirty_card_queue_set()) {
3527 }
3528
3529 virtual bool doHeapRegion(HeapRegion* r) {
3530 if (!r->is_starts_humongous()) {
3531 return false;
3532 }
3533 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3534
3535 bool is_candidate = humongous_region_is_candidate(g1h, r);
3536 uint rindex = r->hrm_index();
3537 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3538 if (is_candidate) {
3539 _candidate_humongous++;
3540 g1h->register_humongous_region_with_cset(rindex);
3541 // Is_candidate already filters out humongous object with large remembered sets.
3542 // If we have a humongous object with a few remembered sets, we simply flush these
3543 // remembered set entries into the DCQS. That will result in automatic
3544 // re-evaluation of their remembered set entries during the following evacuation
3545 // phase.
3546 if (!r->rem_set()->is_empty()) {
3547 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3548 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3549 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3550 HeapRegionRemSetIterator hrrs(r->rem_set());
3551 size_t card_index;
3552 while (hrrs.has_next(card_index)) {
3553 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3554 // The remembered set might contain references to already freed
3555 // regions. Filter out such entries to avoid failing card table
3556 // verification.
3557 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3558 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3559 *card_ptr = CardTableModRefBS::dirty_card_val();
3560 _dcq.enqueue(card_ptr);
3561 }
3562 }
3563 }
3564 guarantee(r->rem_set()->occupied() == hrrs.n_yielded(),
3565 "All entries should have been handled, occupied: " SIZE_FORMAT " n_yielded: " SIZE_FORMAT,
3566 r->rem_set()->occupied(), hrrs.n_yielded());
3567 r->rem_set()->clear_locked();
3568 }
3569 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3570 }
3571 _total_humongous++;
3572
3573 return false;
3574 }
3575
3576 size_t total_humongous() const { return _total_humongous; }
3577 size_t candidate_humongous() const { return _candidate_humongous; }
3578
3579 void flush_rem_set_entries() { _dcq.flush(); }
3580 };
3581
3582 void G1CollectedHeap::register_humongous_regions_with_cset() {
3583 if (!G1EagerReclaimHumongousObjects) {
3584 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3585 return;
3586 }
3587 double time = os::elapsed_counter();
3588
3589 // Collect reclaim candidate information and register candidates with cset.
3590 RegisterHumongousWithInCSetFastTestClosure cl;
3591 heap_region_iterate(&cl);
3592
3593 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3594 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3595 cl.total_humongous(),
3596 cl.candidate_humongous());
3597 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3598
3599 // Finally flush all remembered set entries to re-check into the global DCQS.
3600 cl.flush_rem_set_entries();
3601 }
3602
3603 #ifdef ASSERT
3604 class VerifyCSetClosure: public HeapRegionClosure {
3605 public:
3606 bool doHeapRegion(HeapRegion* hr) {
3607 // Here we check that the CSet region's RSet is ready for parallel
3608 // iteration. The fields that we'll verify are only manipulated
3609 // when the region is part of a CSet and is collected. Afterwards,
3610 // we reset these fields when we clear the region's RSet (when the
3611 // region is freed) so they are ready when the region is
3612 // re-allocated. The only exception to this is if there's an
3613 // evacuation failure and instead of freeing the region we leave
3614 // it in the heap. In that case, we reset these fields during
3615 // evacuation failure handling.
3616 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3617
3618 // Here's a good place to add any other checks we'd like to
3619 // perform on CSet regions.
3620 return false;
3621 }
3622 };
3623 #endif // ASSERT
3624
3625 uint G1CollectedHeap::num_task_queues() const {
3626 return _task_queues->size();
3627 }
3628
3629 #if TASKQUEUE_STATS
3630 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3631 st->print_raw_cr("GC Task Stats");
3632 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3633 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3634 }
3635
3636 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3637 print_taskqueue_stats_hdr(st);
3638
3639 TaskQueueStats totals;
3640 const uint n = num_task_queues();
3641 for (uint i = 0; i < n; ++i) {
3642 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3643 totals += task_queue(i)->stats;
3644 }
3645 st->print_raw("tot "); totals.print(st); st->cr();
3646
3647 DEBUG_ONLY(totals.verify());
3648 }
3649
3650 void G1CollectedHeap::reset_taskqueue_stats() {
3651 const uint n = num_task_queues();
3652 for (uint i = 0; i < n; ++i) {
3653 task_queue(i)->stats.reset();
3654 }
3655 }
3656 #endif // TASKQUEUE_STATS
3657
3658 void G1CollectedHeap::log_gc_header() {
3659 if (!G1Log::fine()) {
3660 return;
3661 }
3662
3663 gclog_or_tty->gclog_stamp();
3664
3665 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3666 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3667 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3668
3669 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3670 }
3671
3672 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3673 if (!G1Log::fine()) {
3674 return;
3675 }
3676
3677 if (G1Log::finer()) {
3678 if (evacuation_failed()) {
3679 gclog_or_tty->print(" (to-space exhausted)");
3680 }
3681 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3682 g1_policy()->print_phases(pause_time_sec);
3683 g1_policy()->print_detailed_heap_transition();
3684 } else {
3685 if (evacuation_failed()) {
3686 gclog_or_tty->print("--");
3687 }
3688 g1_policy()->print_heap_transition();
3689 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3690 }
3691 gclog_or_tty->flush();
3692 }
3693
3694 void G1CollectedHeap::wait_for_root_region_scanning() {
3695 double scan_wait_start = os::elapsedTime();
3696 // We have to wait until the CM threads finish scanning the
3697 // root regions as it's the only way to ensure that all the
3698 // objects on them have been correctly scanned before we start
3699 // moving them during the GC.
3700 bool waited = _cm->root_regions()->wait_until_scan_finished();
3701 double wait_time_ms = 0.0;
3702 if (waited) {
3703 double scan_wait_end = os::elapsedTime();
3704 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3705 }
3706 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3707 }
3708
3709 bool
3710 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3711 assert_at_safepoint(true /* should_be_vm_thread */);
3712 guarantee(!is_gc_active(), "collection is not reentrant");
3713
3714 if (GC_locker::check_active_before_gc()) {
3715 return false;
3716 }
3717
3718 _gc_timer_stw->register_gc_start();
3719
3720 GCIdMark gc_id_mark;
3721 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3722
3723 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3724 ResourceMark rm;
3725
3726 wait_for_root_region_scanning();
3727
3728 G1Log::update_level();
3729 print_heap_before_gc();
3730 trace_heap_before_gc(_gc_tracer_stw);
3731
3732 verify_region_sets_optional();
3733 verify_dirty_young_regions();
3734
3735 // This call will decide whether this pause is an initial-mark
3736 // pause. If it is, during_initial_mark_pause() will return true
3737 // for the duration of this pause.
3738 g1_policy()->decide_on_conc_mark_initiation();
3739
3740 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3741 assert(!collector_state()->during_initial_mark_pause() ||
3742 collector_state()->gcs_are_young(), "sanity");
3743
3744 // We also do not allow mixed GCs during marking.
3745 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3746
3747 // Record whether this pause is an initial mark. When the current
3748 // thread has completed its logging output and it's safe to signal
3749 // the CM thread, the flag's value in the policy has been reset.
3750 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3751
3752 // Inner scope for scope based logging, timers, and stats collection
3753 {
3754 EvacuationInfo evacuation_info;
3755
3756 if (collector_state()->during_initial_mark_pause()) {
3757 // We are about to start a marking cycle, so we increment the
3758 // full collection counter.
3759 increment_old_marking_cycles_started();
3760 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3761 }
3762
3763 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3764
3765 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3766
3767 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3768 workers()->active_workers(),
3769 Threads::number_of_non_daemon_threads());
3770 workers()->set_active_workers(active_workers);
3771
3772 double pause_start_sec = os::elapsedTime();
3773 g1_policy()->note_gc_start(active_workers);
3774 log_gc_header();
3775
3776 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3777 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3778
3779 // If the secondary_free_list is not empty, append it to the
3780 // free_list. No need to wait for the cleanup operation to finish;
3781 // the region allocation code will check the secondary_free_list
3782 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3783 // set, skip this step so that the region allocation code has to
3784 // get entries from the secondary_free_list.
3785 if (!G1StressConcRegionFreeing) {
3786 append_secondary_free_list_if_not_empty_with_lock();
3787 }
3788
3789 assert(check_young_list_well_formed(), "young list should be well formed");
3790
3791 // Don't dynamically change the number of GC threads this early. A value of
3792 // 0 is used to indicate serial work. When parallel work is done,
3793 // it will be set.
3794
3795 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3796 IsGCActiveMark x;
3797
3798 gc_prologue(false);
3799 increment_total_collections(false /* full gc */);
3800 increment_gc_time_stamp();
3801
3802 verify_before_gc();
3803
3804 check_bitmaps("GC Start");
3805
3806 #if defined(COMPILER2) || INCLUDE_JVMCI
3807 DerivedPointerTable::clear();
3808 #endif
3809
3810 // Please see comment in g1CollectedHeap.hpp and
3811 // G1CollectedHeap::ref_processing_init() to see how
3812 // reference processing currently works in G1.
3813
3814 // Enable discovery in the STW reference processor
3815 ref_processor_stw()->enable_discovery();
3816
3817 {
3818 // We want to temporarily turn off discovery by the
3819 // CM ref processor, if necessary, and turn it back on
3820 // on again later if we do. Using a scoped
3821 // NoRefDiscovery object will do this.
3822 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3823
3824 // Forget the current alloc region (we might even choose it to be part
3825 // of the collection set!).
3826 _allocator->release_mutator_alloc_region();
3827
3828 // We should call this after we retire the mutator alloc
3829 // region(s) so that all the ALLOC / RETIRE events are generated
3830 // before the start GC event.
3831 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3832
3833 // This timing is only used by the ergonomics to handle our pause target.
3834 // It is unclear why this should not include the full pause. We will
3835 // investigate this in CR 7178365.
3836 //
3837 // Preserving the old comment here if that helps the investigation:
3838 //
3839 // The elapsed time induced by the start time below deliberately elides
3840 // the possible verification above.
3841 double sample_start_time_sec = os::elapsedTime();
3842
3843 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3844
3845 if (collector_state()->during_initial_mark_pause()) {
3846 concurrent_mark()->checkpointRootsInitialPre();
3847 }
3848
3849 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3850 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3851
3852 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3853
3854 // Make sure the remembered sets are up to date. This needs to be
3855 // done before register_humongous_regions_with_cset(), otherwise
3856 // we might miss some entries that needs to be handled.
3857 g1_rem_set()->cleanupHRRS();
3858
3859 register_humongous_regions_with_cset();
3860
3861 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3862
3863 _cm->note_start_of_gc();
3864 // We call this after finalize_cset() to
3865 // ensure that the CSet has been finalized.
3866 _cm->verify_no_cset_oops();
3867
3868 if (_hr_printer.is_active()) {
3869 HeapRegion* hr = g1_policy()->collection_set();
3870 while (hr != NULL) {
3871 _hr_printer.cset(hr);
3872 hr = hr->next_in_collection_set();
3873 }
3874 }
3875
3876 #ifdef ASSERT
3877 VerifyCSetClosure cl;
3878 collection_set_iterate(&cl);
3879 #endif // ASSERT
3880
3881 // Initialize the GC alloc regions.
3882 _allocator->init_gc_alloc_regions(evacuation_info);
3883
3884 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3885 pre_evacuate_collection_set();
3886
3887 // Actually do the work...
3888 evacuate_collection_set(evacuation_info, &per_thread_states);
3889
3890 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3891
3892 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3893 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3894
3895 eagerly_reclaim_humongous_regions();
3896
3897 g1_policy()->clear_collection_set();
3898
3899 // Start a new incremental collection set for the next pause.
3900 g1_policy()->start_incremental_cset_building();
3901
3902 clear_cset_fast_test();
3903
3904 _young_list->reset_sampled_info();
3905
3906 // Don't check the whole heap at this point as the
3907 // GC alloc regions from this pause have been tagged
3908 // as survivors and moved on to the survivor list.
3909 // Survivor regions will fail the !is_young() check.
3910 assert(check_young_list_empty(false /* check_heap */),
3911 "young list should be empty");
3912
3913 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3914 _young_list->first_survivor_region(),
3915 _young_list->last_survivor_region());
3916
3917 _young_list->reset_auxilary_lists();
3918
3919 if (evacuation_failed()) {
3920 set_used(recalculate_used());
3921 if (_archive_allocator != NULL) {
3922 _archive_allocator->clear_used();
3923 }
3924 for (uint i = 0; i < ParallelGCThreads; i++) {
3925 if (_evacuation_failed_info_array[i].has_failed()) {
3926 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3927 }
3928 }
3929 } else {
3930 // The "used" of the the collection set have already been subtracted
3931 // when they were freed. Add in the bytes evacuated.
3932 increase_used(g1_policy()->bytes_copied_during_gc());
3933 }
3934
3935 if (collector_state()->during_initial_mark_pause()) {
3936 // We have to do this before we notify the CM threads that
3937 // they can start working to make sure that all the
3938 // appropriate initialization is done on the CM object.
3939 concurrent_mark()->checkpointRootsInitialPost();
3940 collector_state()->set_mark_in_progress(true);
3941 // Note that we don't actually trigger the CM thread at
3942 // this point. We do that later when we're sure that
3943 // the current thread has completed its logging output.
3944 }
3945
3946 allocate_dummy_regions();
3947
3948 _allocator->init_mutator_alloc_region();
3949
3950 {
3951 size_t expand_bytes = g1_policy()->expansion_amount();
3952 if (expand_bytes > 0) {
3953 size_t bytes_before = capacity();
3954 // No need for an ergo verbose message here,
3955 // expansion_amount() does this when it returns a value > 0.
3956 double expand_ms;
3957 if (!expand(expand_bytes, &expand_ms)) {
3958 // We failed to expand the heap. Cannot do anything about it.
3959 }
3960 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3961 }
3962 }
3963
3964 // We redo the verification but now wrt to the new CSet which
3965 // has just got initialized after the previous CSet was freed.
3966 _cm->verify_no_cset_oops();
3967 _cm->note_end_of_gc();
3968
3969 // This timing is only used by the ergonomics to handle our pause target.
3970 // It is unclear why this should not include the full pause. We will
3971 // investigate this in CR 7178365.
3972 double sample_end_time_sec = os::elapsedTime();
3973 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3974 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3975 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3976
3977 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3978 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3979
3980 MemoryService::track_memory_usage();
3981
3982 // In prepare_for_verify() below we'll need to scan the deferred
3983 // update buffers to bring the RSets up-to-date if
3984 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3985 // the update buffers we'll probably need to scan cards on the
3986 // regions we just allocated to (i.e., the GC alloc
3987 // regions). However, during the last GC we called
3988 // set_saved_mark() on all the GC alloc regions, so card
3989 // scanning might skip the [saved_mark_word()...top()] area of
3990 // those regions (i.e., the area we allocated objects into
3991 // during the last GC). But it shouldn't. Given that
3992 // saved_mark_word() is conditional on whether the GC time stamp
3993 // on the region is current or not, by incrementing the GC time
3994 // stamp here we invalidate all the GC time stamps on all the
3995 // regions and saved_mark_word() will simply return top() for
3996 // all the regions. This is a nicer way of ensuring this rather
3997 // than iterating over the regions and fixing them. In fact, the
3998 // GC time stamp increment here also ensures that
3999 // saved_mark_word() will return top() between pauses, i.e.,
4000 // during concurrent refinement. So we don't need the
4001 // is_gc_active() check to decided which top to use when
4002 // scanning cards (see CR 7039627).
4003 increment_gc_time_stamp();
4004
4005 verify_after_gc();
4006 check_bitmaps("GC End");
4007
4008 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4009 ref_processor_stw()->verify_no_references_recorded();
4010
4011 // CM reference discovery will be re-enabled if necessary.
4012 }
4013
4014 // We should do this after we potentially expand the heap so
4015 // that all the COMMIT events are generated before the end GC
4016 // event, and after we retire the GC alloc regions so that all
4017 // RETIRE events are generated before the end GC event.
4018 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4019
4020 #ifdef TRACESPINNING
4021 ParallelTaskTerminator::print_termination_counts();
4022 #endif
4023
4024 gc_epilogue(false);
4025 }
4026
4027 // Print the remainder of the GC log output.
4028 log_gc_footer(os::elapsedTime() - pause_start_sec);
4029
4030 // It is not yet to safe to tell the concurrent mark to
4031 // start as we have some optional output below. We don't want the
4032 // output from the concurrent mark thread interfering with this
4033 // logging output either.
4034
4035 _hrm.verify_optional();
4036 verify_region_sets_optional();
4037
4038 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4039 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4040
4041 print_heap_after_gc();
4042 trace_heap_after_gc(_gc_tracer_stw);
4043
4044 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4045 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4046 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4047 // before any GC notifications are raised.
4048 g1mm()->update_sizes();
4049
4050 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4051 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4052 _gc_timer_stw->register_gc_end();
4053 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4054 }
4055 // It should now be safe to tell the concurrent mark thread to start
4056 // without its logging output interfering with the logging output
4057 // that came from the pause.
4058
4059 if (should_start_conc_mark) {
4060 // CAUTION: after the doConcurrentMark() call below,
4061 // the concurrent marking thread(s) could be running
4062 // concurrently with us. Make sure that anything after
4063 // this point does not assume that we are the only GC thread
4064 // running. Note: of course, the actual marking work will
4065 // not start until the safepoint itself is released in
4066 // SuspendibleThreadSet::desynchronize().
4067 doConcurrentMark();
4068 }
4069
4070 return true;
4071 }
4072
4073 void G1CollectedHeap::remove_self_forwarding_pointers() {
4074 double remove_self_forwards_start = os::elapsedTime();
4075
4076 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4077 workers()->run_task(&rsfp_task);
4078
4079 // Now restore saved marks, if any.
4080 for (uint i = 0; i < ParallelGCThreads; i++) {
4081 OopAndMarkOopStack& cur = _preserved_objs[i];
4082 while (!cur.is_empty()) {
4083 OopAndMarkOop elem = cur.pop();
4084 elem.set_mark();
4085 }
4086 cur.clear(true);
4087 }
4088
4089 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4090 }
4091
4092 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4093 if (!_evacuation_failed) {
4094 _evacuation_failed = true;
4095 }
4096
4097 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4098
4099 // We want to call the "for_promotion_failure" version only in the
4100 // case of a promotion failure.
4101 if (m->must_be_preserved_for_promotion_failure(obj)) {
4102 OopAndMarkOop elem(obj, m);
4103 _preserved_objs[worker_id].push(elem);
4104 }
4105 }
4106
4107 class G1ParEvacuateFollowersClosure : public VoidClosure {
4108 private:
4109 double _start_term;
4110 double _term_time;
4111 size_t _term_attempts;
4112
4113 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4114 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4115 protected:
4116 G1CollectedHeap* _g1h;
4117 G1ParScanThreadState* _par_scan_state;
4118 RefToScanQueueSet* _queues;
4119 ParallelTaskTerminator* _terminator;
4120
4121 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4122 RefToScanQueueSet* queues() { return _queues; }
4123 ParallelTaskTerminator* terminator() { return _terminator; }
4124
4125 public:
4126 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4127 G1ParScanThreadState* par_scan_state,
4128 RefToScanQueueSet* queues,
4129 ParallelTaskTerminator* terminator)
4130 : _g1h(g1h), _par_scan_state(par_scan_state),
4131 _queues(queues), _terminator(terminator),
4132 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4133
4134 void do_void();
4135
4136 double term_time() const { return _term_time; }
4137 size_t term_attempts() const { return _term_attempts; }
4138
4139 private:
4140 inline bool offer_termination();
4141 };
4142
4143 bool G1ParEvacuateFollowersClosure::offer_termination() {
4144 G1ParScanThreadState* const pss = par_scan_state();
4145 start_term_time();
4146 const bool res = terminator()->offer_termination();
4147 end_term_time();
4148 return res;
4149 }
4150
4151 void G1ParEvacuateFollowersClosure::do_void() {
4152 G1ParScanThreadState* const pss = par_scan_state();
4153 pss->trim_queue();
4154 do {
4155 pss->steal_and_trim_queue(queues());
4156 } while (!offer_termination());
4157 }
4158
4159 class G1ParTask : public AbstractGangTask {
4160 protected:
4161 G1CollectedHeap* _g1h;
4162 G1ParScanThreadStateSet* _pss;
4163 RefToScanQueueSet* _queues;
4164 G1RootProcessor* _root_processor;
4165 ParallelTaskTerminator _terminator;
4166 uint _n_workers;
4167
4168 public:
4169 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4170 : AbstractGangTask("G1 collection"),
4171 _g1h(g1h),
4172 _pss(per_thread_states),
4173 _queues(task_queues),
4174 _root_processor(root_processor),
4175 _terminator(n_workers, _queues),
4176 _n_workers(n_workers)
4177 {}
4178
4179 void work(uint worker_id) {
4180 if (worker_id >= _n_workers) return; // no work needed this round
4181
4182 double start_sec = os::elapsedTime();
4183 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4184
4185 {
4186 ResourceMark rm;
4187 HandleMark hm;
4188
4189 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4190
4191 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4192 pss->set_ref_processor(rp);
4193
4194 double start_strong_roots_sec = os::elapsedTime();
4195
4196 _root_processor->evacuate_roots(pss->closures(), worker_id);
4197
4198 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4199
4200 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4201 // treating the nmethods visited to act as roots for concurrent marking.
4202 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4203 // objects copied by the current evacuation.
4204 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4205 pss->closures()->weak_codeblobs(),
4206 worker_id);
4207
4208 _pss->add_cards_scanned(worker_id, cards_scanned);
4209
4210 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4211
4212 double term_sec = 0.0;
4213 size_t evac_term_attempts = 0;
4214 {
4215 double start = os::elapsedTime();
4216 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4217 evac.do_void();
4218
4219 evac_term_attempts = evac.term_attempts();
4220 term_sec = evac.term_time();
4221 double elapsed_sec = os::elapsedTime() - start;
4222 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4223 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4224 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4225 }
4226
4227 assert(pss->queue_is_empty(), "should be empty");
4228
4229 if (PrintTerminationStats) {
4230 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4231 size_t lab_waste;
4232 size_t lab_undo_waste;
4233 pss->waste(lab_waste, lab_undo_waste);
4234 _g1h->print_termination_stats(gclog_or_tty,
4235 worker_id,
4236 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4237 strong_roots_sec * 1000.0, /* strong roots time */
4238 term_sec * 1000.0, /* evac term time */
4239 evac_term_attempts, /* evac term attempts */
4240 lab_waste, /* alloc buffer waste */
4241 lab_undo_waste /* undo waste */
4242 );
4243 }
4244
4245 // Close the inner scope so that the ResourceMark and HandleMark
4246 // destructors are executed here and are included as part of the
4247 // "GC Worker Time".
4248 }
4249 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4250 }
4251 };
4252
4253 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4254 st->print_raw_cr("GC Termination Stats");
4255 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4256 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4257 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4258 }
4259
4260 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4261 uint worker_id,
4262 double elapsed_ms,
4263 double strong_roots_ms,
4264 double term_ms,
4265 size_t term_attempts,
4266 size_t alloc_buffer_waste,
4267 size_t undo_waste) const {
4268 st->print_cr("%3d %9.2f %9.2f %6.2f "
4269 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4270 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4271 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4272 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4273 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4274 alloc_buffer_waste * HeapWordSize / K,
4275 undo_waste * HeapWordSize / K);
4276 }
4277
4278 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4279 private:
4280 BoolObjectClosure* _is_alive;
4281 int _initial_string_table_size;
4282 int _initial_symbol_table_size;
4283
4284 bool _process_strings;
4285 int _strings_processed;
4286 int _strings_removed;
4287
4288 bool _process_symbols;
4289 int _symbols_processed;
4290 int _symbols_removed;
4291
4292 public:
4293 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4294 AbstractGangTask("String/Symbol Unlinking"),
4295 _is_alive(is_alive),
4296 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4297 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4298
4299 _initial_string_table_size = StringTable::the_table()->table_size();
4300 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4301 if (process_strings) {
4302 StringTable::clear_parallel_claimed_index();
4303 }
4304 if (process_symbols) {
4305 SymbolTable::clear_parallel_claimed_index();
4306 }
4307 }
4308
4309 ~G1StringSymbolTableUnlinkTask() {
4310 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4311 "claim value %d after unlink less than initial string table size %d",
4312 StringTable::parallel_claimed_index(), _initial_string_table_size);
4313 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4314 "claim value %d after unlink less than initial symbol table size %d",
4315 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4316
4317 if (G1TraceStringSymbolTableScrubbing) {
4318 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4319 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4320 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4321 strings_processed(), strings_removed(),
4322 symbols_processed(), symbols_removed());
4323 }
4324 }
4325
4326 void work(uint worker_id) {
4327 int strings_processed = 0;
4328 int strings_removed = 0;
4329 int symbols_processed = 0;
4330 int symbols_removed = 0;
4331 if (_process_strings) {
4332 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4333 Atomic::add(strings_processed, &_strings_processed);
4334 Atomic::add(strings_removed, &_strings_removed);
4335 }
4336 if (_process_symbols) {
4337 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4338 Atomic::add(symbols_processed, &_symbols_processed);
4339 Atomic::add(symbols_removed, &_symbols_removed);
4340 }
4341 }
4342
4343 size_t strings_processed() const { return (size_t)_strings_processed; }
4344 size_t strings_removed() const { return (size_t)_strings_removed; }
4345
4346 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4347 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4348 };
4349
4350 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4351 private:
4352 static Monitor* _lock;
4353
4354 BoolObjectClosure* const _is_alive;
4355 const bool _unloading_occurred;
4356 const uint _num_workers;
4357
4358 // Variables used to claim nmethods.
4359 nmethod* _first_nmethod;
4360 volatile nmethod* _claimed_nmethod;
4361
4362 // The list of nmethods that need to be processed by the second pass.
4363 volatile nmethod* _postponed_list;
4364 volatile uint _num_entered_barrier;
4365
4366 public:
4367 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4368 _is_alive(is_alive),
4369 _unloading_occurred(unloading_occurred),
4370 _num_workers(num_workers),
4371 _first_nmethod(NULL),
4372 _claimed_nmethod(NULL),
4373 _postponed_list(NULL),
4374 _num_entered_barrier(0)
4375 {
4376 nmethod::increase_unloading_clock();
4377 // Get first alive nmethod
4378 NMethodIterator iter = NMethodIterator();
4379 if(iter.next_alive()) {
4380 _first_nmethod = iter.method();
4381 }
4382 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4383 }
4384
4385 ~G1CodeCacheUnloadingTask() {
4386 CodeCache::verify_clean_inline_caches();
4387
4388 CodeCache::set_needs_cache_clean(false);
4389 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4390
4391 CodeCache::verify_icholder_relocations();
4392 }
4393
4394 private:
4395 void add_to_postponed_list(nmethod* nm) {
4396 nmethod* old;
4397 do {
4398 old = (nmethod*)_postponed_list;
4399 nm->set_unloading_next(old);
4400 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4401 }
4402
4403 void clean_nmethod(nmethod* nm) {
4404 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4405
4406 if (postponed) {
4407 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4408 add_to_postponed_list(nm);
4409 }
4410
4411 // Mark that this thread has been cleaned/unloaded.
4412 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4413 nm->set_unloading_clock(nmethod::global_unloading_clock());
4414 }
4415
4416 void clean_nmethod_postponed(nmethod* nm) {
4417 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4418 }
4419
4420 static const int MaxClaimNmethods = 16;
4421
4422 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4423 nmethod* first;
4424 NMethodIterator last;
4425
4426 do {
4427 *num_claimed_nmethods = 0;
4428
4429 first = (nmethod*)_claimed_nmethod;
4430 last = NMethodIterator(first);
4431
4432 if (first != NULL) {
4433
4434 for (int i = 0; i < MaxClaimNmethods; i++) {
4435 if (!last.next_alive()) {
4436 break;
4437 }
4438 claimed_nmethods[i] = last.method();
4439 (*num_claimed_nmethods)++;
4440 }
4441 }
4442
4443 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4444 }
4445
4446 nmethod* claim_postponed_nmethod() {
4447 nmethod* claim;
4448 nmethod* next;
4449
4450 do {
4451 claim = (nmethod*)_postponed_list;
4452 if (claim == NULL) {
4453 return NULL;
4454 }
4455
4456 next = claim->unloading_next();
4457
4458 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4459
4460 return claim;
4461 }
4462
4463 public:
4464 // Mark that we're done with the first pass of nmethod cleaning.
4465 void barrier_mark(uint worker_id) {
4466 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4467 _num_entered_barrier++;
4468 if (_num_entered_barrier == _num_workers) {
4469 ml.notify_all();
4470 }
4471 }
4472
4473 // See if we have to wait for the other workers to
4474 // finish their first-pass nmethod cleaning work.
4475 void barrier_wait(uint worker_id) {
4476 if (_num_entered_barrier < _num_workers) {
4477 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4478 while (_num_entered_barrier < _num_workers) {
4479 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4480 }
4481 }
4482 }
4483
4484 // Cleaning and unloading of nmethods. Some work has to be postponed
4485 // to the second pass, when we know which nmethods survive.
4486 void work_first_pass(uint worker_id) {
4487 // The first nmethods is claimed by the first worker.
4488 if (worker_id == 0 && _first_nmethod != NULL) {
4489 clean_nmethod(_first_nmethod);
4490 _first_nmethod = NULL;
4491 }
4492
4493 int num_claimed_nmethods;
4494 nmethod* claimed_nmethods[MaxClaimNmethods];
4495
4496 while (true) {
4497 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4498
4499 if (num_claimed_nmethods == 0) {
4500 break;
4501 }
4502
4503 for (int i = 0; i < num_claimed_nmethods; i++) {
4504 clean_nmethod(claimed_nmethods[i]);
4505 }
4506 }
4507 }
4508
4509 void work_second_pass(uint worker_id) {
4510 nmethod* nm;
4511 // Take care of postponed nmethods.
4512 while ((nm = claim_postponed_nmethod()) != NULL) {
4513 clean_nmethod_postponed(nm);
4514 }
4515 }
4516 };
4517
4518 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4519
4520 class G1KlassCleaningTask : public StackObj {
4521 BoolObjectClosure* _is_alive;
4522 volatile jint _clean_klass_tree_claimed;
4523 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4524
4525 public:
4526 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4527 _is_alive(is_alive),
4528 _clean_klass_tree_claimed(0),
4529 _klass_iterator() {
4530 }
4531
4532 private:
4533 bool claim_clean_klass_tree_task() {
4534 if (_clean_klass_tree_claimed) {
4535 return false;
4536 }
4537
4538 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4539 }
4540
4541 InstanceKlass* claim_next_klass() {
4542 Klass* klass;
4543 do {
4544 klass =_klass_iterator.next_klass();
4545 } while (klass != NULL && !klass->is_instance_klass());
4546
4547 // this can be null so don't call InstanceKlass::cast
4548 return static_cast<InstanceKlass*>(klass);
4549 }
4550
4551 public:
4552
4553 void clean_klass(InstanceKlass* ik) {
4554 ik->clean_weak_instanceklass_links(_is_alive);
4555 }
4556
4557 void work() {
4558 ResourceMark rm;
4559
4560 // One worker will clean the subklass/sibling klass tree.
4561 if (claim_clean_klass_tree_task()) {
4562 Klass::clean_subklass_tree(_is_alive);
4563 }
4564
4565 // All workers will help cleaning the classes,
4566 InstanceKlass* klass;
4567 while ((klass = claim_next_klass()) != NULL) {
4568 clean_klass(klass);
4569 }
4570 }
4571 };
4572
4573 // To minimize the remark pause times, the tasks below are done in parallel.
4574 class G1ParallelCleaningTask : public AbstractGangTask {
4575 private:
4576 G1StringSymbolTableUnlinkTask _string_symbol_task;
4577 G1CodeCacheUnloadingTask _code_cache_task;
4578 G1KlassCleaningTask _klass_cleaning_task;
4579
4580 public:
4581 // The constructor is run in the VMThread.
4582 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4583 AbstractGangTask("Parallel Cleaning"),
4584 _string_symbol_task(is_alive, process_strings, process_symbols),
4585 _code_cache_task(num_workers, is_alive, unloading_occurred),
4586 _klass_cleaning_task(is_alive) {
4587 }
4588
4589 // The parallel work done by all worker threads.
4590 void work(uint worker_id) {
4591 // Do first pass of code cache cleaning.
4592 _code_cache_task.work_first_pass(worker_id);
4593
4594 // Let the threads mark that the first pass is done.
4595 _code_cache_task.barrier_mark(worker_id);
4596
4597 // Clean the Strings and Symbols.
4598 _string_symbol_task.work(worker_id);
4599
4600 // Wait for all workers to finish the first code cache cleaning pass.
4601 _code_cache_task.barrier_wait(worker_id);
4602
4603 // Do the second code cache cleaning work, which realize on
4604 // the liveness information gathered during the first pass.
4605 _code_cache_task.work_second_pass(worker_id);
4606
4607 // Clean all klasses that were not unloaded.
4608 _klass_cleaning_task.work();
4609 }
4610 };
4611
4612
4613 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4614 bool process_strings,
4615 bool process_symbols,
4616 bool class_unloading_occurred) {
4617 uint n_workers = workers()->active_workers();
4618
4619 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4620 n_workers, class_unloading_occurred);
4621 workers()->run_task(&g1_unlink_task);
4622 }
4623
4624 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4625 bool process_strings, bool process_symbols) {
4626 {
4627 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4628 workers()->run_task(&g1_unlink_task);
4629 }
4630
4631 if (G1StringDedup::is_enabled()) {
4632 G1StringDedup::unlink(is_alive);
4633 }
4634 }
4635
4636 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4637 private:
4638 DirtyCardQueueSet* _queue;
4639 public:
4640 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4641
4642 virtual void work(uint worker_id) {
4643 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4644 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4645
4646 RedirtyLoggedCardTableEntryClosure cl;
4647 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4648
4649 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4650 }
4651 };
4652
4653 void G1CollectedHeap::redirty_logged_cards() {
4654 double redirty_logged_cards_start = os::elapsedTime();
4655
4656 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4657 dirty_card_queue_set().reset_for_par_iteration();
4658 workers()->run_task(&redirty_task);
4659
4660 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4661 dcq.merge_bufferlists(&dirty_card_queue_set());
4662 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4663
4664 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4665 }
4666
4667 // Weak Reference Processing support
4668
4669 // An always "is_alive" closure that is used to preserve referents.
4670 // If the object is non-null then it's alive. Used in the preservation
4671 // of referent objects that are pointed to by reference objects
4672 // discovered by the CM ref processor.
4673 class G1AlwaysAliveClosure: public BoolObjectClosure {
4674 G1CollectedHeap* _g1;
4675 public:
4676 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4677 bool do_object_b(oop p) {
4678 if (p != NULL) {
4679 return true;
4680 }
4681 return false;
4682 }
4683 };
4684
4685 bool G1STWIsAliveClosure::do_object_b(oop p) {
4686 // An object is reachable if it is outside the collection set,
4687 // or is inside and copied.
4688 return !_g1->is_in_cset(p) || p->is_forwarded();
4689 }
4690
4691 // Non Copying Keep Alive closure
4692 class G1KeepAliveClosure: public OopClosure {
4693 G1CollectedHeap* _g1;
4694 public:
4695 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4696 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4697 void do_oop(oop* p) {
4698 oop obj = *p;
4699 assert(obj != NULL, "the caller should have filtered out NULL values");
4700
4701 const InCSetState cset_state = _g1->in_cset_state(obj);
4702 if (!cset_state.is_in_cset_or_humongous()) {
4703 return;
4704 }
4705 if (cset_state.is_in_cset()) {
4706 assert( obj->is_forwarded(), "invariant" );
4707 *p = obj->forwardee();
4708 } else {
4709 assert(!obj->is_forwarded(), "invariant" );
4710 assert(cset_state.is_humongous(),
4711 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4712 _g1->set_humongous_is_live(obj);
4713 }
4714 }
4715 };
4716
4717 // Copying Keep Alive closure - can be called from both
4718 // serial and parallel code as long as different worker
4719 // threads utilize different G1ParScanThreadState instances
4720 // and different queues.
4721
4722 class G1CopyingKeepAliveClosure: public OopClosure {
4723 G1CollectedHeap* _g1h;
4724 OopClosure* _copy_non_heap_obj_cl;
4725 G1ParScanThreadState* _par_scan_state;
4726
4727 public:
4728 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4729 OopClosure* non_heap_obj_cl,
4730 G1ParScanThreadState* pss):
4731 _g1h(g1h),
4732 _copy_non_heap_obj_cl(non_heap_obj_cl),
4733 _par_scan_state(pss)
4734 {}
4735
4736 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4737 virtual void do_oop( oop* p) { do_oop_work(p); }
4738
4739 template <class T> void do_oop_work(T* p) {
4740 oop obj = oopDesc::load_decode_heap_oop(p);
4741
4742 if (_g1h->is_in_cset_or_humongous(obj)) {
4743 // If the referent object has been forwarded (either copied
4744 // to a new location or to itself in the event of an
4745 // evacuation failure) then we need to update the reference
4746 // field and, if both reference and referent are in the G1
4747 // heap, update the RSet for the referent.
4748 //
4749 // If the referent has not been forwarded then we have to keep
4750 // it alive by policy. Therefore we have copy the referent.
4751 //
4752 // If the reference field is in the G1 heap then we can push
4753 // on the PSS queue. When the queue is drained (after each
4754 // phase of reference processing) the object and it's followers
4755 // will be copied, the reference field set to point to the
4756 // new location, and the RSet updated. Otherwise we need to
4757 // use the the non-heap or metadata closures directly to copy
4758 // the referent object and update the pointer, while avoiding
4759 // updating the RSet.
4760
4761 if (_g1h->is_in_g1_reserved(p)) {
4762 _par_scan_state->push_on_queue(p);
4763 } else {
4764 assert(!Metaspace::contains((const void*)p),
4765 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4766 _copy_non_heap_obj_cl->do_oop(p);
4767 }
4768 }
4769 }
4770 };
4771
4772 // Serial drain queue closure. Called as the 'complete_gc'
4773 // closure for each discovered list in some of the
4774 // reference processing phases.
4775
4776 class G1STWDrainQueueClosure: public VoidClosure {
4777 protected:
4778 G1CollectedHeap* _g1h;
4779 G1ParScanThreadState* _par_scan_state;
4780
4781 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4782
4783 public:
4784 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4785 _g1h(g1h),
4786 _par_scan_state(pss)
4787 { }
4788
4789 void do_void() {
4790 G1ParScanThreadState* const pss = par_scan_state();
4791 pss->trim_queue();
4792 }
4793 };
4794
4795 // Parallel Reference Processing closures
4796
4797 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4798 // processing during G1 evacuation pauses.
4799
4800 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4801 private:
4802 G1CollectedHeap* _g1h;
4803 G1ParScanThreadStateSet* _pss;
4804 RefToScanQueueSet* _queues;
4805 WorkGang* _workers;
4806 uint _active_workers;
4807
4808 public:
4809 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4810 G1ParScanThreadStateSet* per_thread_states,
4811 WorkGang* workers,
4812 RefToScanQueueSet *task_queues,
4813 uint n_workers) :
4814 _g1h(g1h),
4815 _pss(per_thread_states),
4816 _queues(task_queues),
4817 _workers(workers),
4818 _active_workers(n_workers)
4819 {
4820 assert(n_workers > 0, "shouldn't call this otherwise");
4821 }
4822
4823 // Executes the given task using concurrent marking worker threads.
4824 virtual void execute(ProcessTask& task);
4825 virtual void execute(EnqueueTask& task);
4826 };
4827
4828 // Gang task for possibly parallel reference processing
4829
4830 class G1STWRefProcTaskProxy: public AbstractGangTask {
4831 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4832 ProcessTask& _proc_task;
4833 G1CollectedHeap* _g1h;
4834 G1ParScanThreadStateSet* _pss;
4835 RefToScanQueueSet* _task_queues;
4836 ParallelTaskTerminator* _terminator;
4837
4838 public:
4839 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4840 G1CollectedHeap* g1h,
4841 G1ParScanThreadStateSet* per_thread_states,
4842 RefToScanQueueSet *task_queues,
4843 ParallelTaskTerminator* terminator) :
4844 AbstractGangTask("Process reference objects in parallel"),
4845 _proc_task(proc_task),
4846 _g1h(g1h),
4847 _pss(per_thread_states),
4848 _task_queues(task_queues),
4849 _terminator(terminator)
4850 {}
4851
4852 virtual void work(uint worker_id) {
4853 // The reference processing task executed by a single worker.
4854 ResourceMark rm;
4855 HandleMark hm;
4856
4857 G1STWIsAliveClosure is_alive(_g1h);
4858
4859 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4860 pss->set_ref_processor(NULL);
4861
4862 // Keep alive closure.
4863 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4864
4865 // Complete GC closure
4866 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4867
4868 // Call the reference processing task's work routine.
4869 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4870
4871 // Note we cannot assert that the refs array is empty here as not all
4872 // of the processing tasks (specifically phase2 - pp2_work) execute
4873 // the complete_gc closure (which ordinarily would drain the queue) so
4874 // the queue may not be empty.
4875 }
4876 };
4877
4878 // Driver routine for parallel reference processing.
4879 // Creates an instance of the ref processing gang
4880 // task and has the worker threads execute it.
4881 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4882 assert(_workers != NULL, "Need parallel worker threads.");
4883
4884 ParallelTaskTerminator terminator(_active_workers, _queues);
4885 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4886
4887 _workers->run_task(&proc_task_proxy);
4888 }
4889
4890 // Gang task for parallel reference enqueueing.
4891
4892 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4893 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4894 EnqueueTask& _enq_task;
4895
4896 public:
4897 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4898 AbstractGangTask("Enqueue reference objects in parallel"),
4899 _enq_task(enq_task)
4900 { }
4901
4902 virtual void work(uint worker_id) {
4903 _enq_task.work(worker_id);
4904 }
4905 };
4906
4907 // Driver routine for parallel reference enqueueing.
4908 // Creates an instance of the ref enqueueing gang
4909 // task and has the worker threads execute it.
4910
4911 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4912 assert(_workers != NULL, "Need parallel worker threads.");
4913
4914 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4915
4916 _workers->run_task(&enq_task_proxy);
4917 }
4918
4919 // End of weak reference support closures
4920
4921 // Abstract task used to preserve (i.e. copy) any referent objects
4922 // that are in the collection set and are pointed to by reference
4923 // objects discovered by the CM ref processor.
4924
4925 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4926 protected:
4927 G1CollectedHeap* _g1h;
4928 G1ParScanThreadStateSet* _pss;
4929 RefToScanQueueSet* _queues;
4930 ParallelTaskTerminator _terminator;
4931 uint _n_workers;
4932
4933 public:
4934 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4935 AbstractGangTask("ParPreserveCMReferents"),
4936 _g1h(g1h),
4937 _pss(per_thread_states),
4938 _queues(task_queues),
4939 _terminator(workers, _queues),
4940 _n_workers(workers)
4941 { }
4942
4943 void work(uint worker_id) {
4944 ResourceMark rm;
4945 HandleMark hm;
4946
4947 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4948 pss->set_ref_processor(NULL);
4949 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4950
4951 // Is alive closure
4952 G1AlwaysAliveClosure always_alive(_g1h);
4953
4954 // Copying keep alive closure. Applied to referent objects that need
4955 // to be copied.
4956 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4957
4958 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4959
4960 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4961 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4962
4963 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4964 // So this must be true - but assert just in case someone decides to
4965 // change the worker ids.
4966 assert(worker_id < limit, "sanity");
4967 assert(!rp->discovery_is_atomic(), "check this code");
4968
4969 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4970 for (uint idx = worker_id; idx < limit; idx += stride) {
4971 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4972
4973 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4974 while (iter.has_next()) {
4975 // Since discovery is not atomic for the CM ref processor, we
4976 // can see some null referent objects.
4977 iter.load_ptrs(DEBUG_ONLY(true));
4978 oop ref = iter.obj();
4979
4980 // This will filter nulls.
4981 if (iter.is_referent_alive()) {
4982 iter.make_referent_alive();
4983 }
4984 iter.move_to_next();
4985 }
4986 }
4987
4988 // Drain the queue - which may cause stealing
4989 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4990 drain_queue.do_void();
4991 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4992 assert(pss->queue_is_empty(), "should be");
4993 }
4994 };
4995
4996 // Weak Reference processing during an evacuation pause (part 1).
4997 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4998 double ref_proc_start = os::elapsedTime();
4999
5000 ReferenceProcessor* rp = _ref_processor_stw;
5001 assert(rp->discovery_enabled(), "should have been enabled");
5002
5003 // Any reference objects, in the collection set, that were 'discovered'
5004 // by the CM ref processor should have already been copied (either by
5005 // applying the external root copy closure to the discovered lists, or
5006 // by following an RSet entry).
5007 //
5008 // But some of the referents, that are in the collection set, that these
5009 // reference objects point to may not have been copied: the STW ref
5010 // processor would have seen that the reference object had already
5011 // been 'discovered' and would have skipped discovering the reference,
5012 // but would not have treated the reference object as a regular oop.
5013 // As a result the copy closure would not have been applied to the
5014 // referent object.
5015 //
5016 // We need to explicitly copy these referent objects - the references
5017 // will be processed at the end of remarking.
5018 //
5019 // We also need to do this copying before we process the reference
5020 // objects discovered by the STW ref processor in case one of these
5021 // referents points to another object which is also referenced by an
5022 // object discovered by the STW ref processor.
5023
5024 uint no_of_gc_workers = workers()->active_workers();
5025
5026 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5027 per_thread_states,
5028 no_of_gc_workers,
5029 _task_queues);
5030
5031 workers()->run_task(&keep_cm_referents);
5032
5033 // Closure to test whether a referent is alive.
5034 G1STWIsAliveClosure is_alive(this);
5035
5036 // Even when parallel reference processing is enabled, the processing
5037 // of JNI refs is serial and performed serially by the current thread
5038 // rather than by a worker. The following PSS will be used for processing
5039 // JNI refs.
5040
5041 // Use only a single queue for this PSS.
5042 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5043 pss->set_ref_processor(NULL);
5044 assert(pss->queue_is_empty(), "pre-condition");
5045
5046 // Keep alive closure.
5047 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5048
5049 // Serial Complete GC closure
5050 G1STWDrainQueueClosure drain_queue(this, pss);
5051
5052 // Setup the soft refs policy...
5053 rp->setup_policy(false);
5054
5055 ReferenceProcessorStats stats;
5056 if (!rp->processing_is_mt()) {
5057 // Serial reference processing...
5058 stats = rp->process_discovered_references(&is_alive,
5059 &keep_alive,
5060 &drain_queue,
5061 NULL,
5062 _gc_timer_stw);
5063 } else {
5064 // Parallel reference processing
5065 assert(rp->num_q() == no_of_gc_workers, "sanity");
5066 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5067
5068 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5069 stats = rp->process_discovered_references(&is_alive,
5070 &keep_alive,
5071 &drain_queue,
5072 &par_task_executor,
5073 _gc_timer_stw);
5074 }
5075
5076 _gc_tracer_stw->report_gc_reference_stats(stats);
5077
5078 // We have completed copying any necessary live referent objects.
5079 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5080
5081 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5082 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5083 }
5084
5085 // Weak Reference processing during an evacuation pause (part 2).
5086 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5087 double ref_enq_start = os::elapsedTime();
5088
5089 ReferenceProcessor* rp = _ref_processor_stw;
5090 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5091
5092 // Now enqueue any remaining on the discovered lists on to
5093 // the pending list.
5094 if (!rp->processing_is_mt()) {
5095 // Serial reference processing...
5096 rp->enqueue_discovered_references();
5097 } else {
5098 // Parallel reference enqueueing
5099
5100 uint n_workers = workers()->active_workers();
5101
5102 assert(rp->num_q() == n_workers, "sanity");
5103 assert(n_workers <= rp->max_num_q(), "sanity");
5104
5105 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5106 rp->enqueue_discovered_references(&par_task_executor);
5107 }
5108
5109 rp->verify_no_references_recorded();
5110 assert(!rp->discovery_enabled(), "should have been disabled");
5111
5112 // FIXME
5113 // CM's reference processing also cleans up the string and symbol tables.
5114 // Should we do that here also? We could, but it is a serial operation
5115 // and could significantly increase the pause time.
5116
5117 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5118 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5119 }
5120
5121 void G1CollectedHeap::pre_evacuate_collection_set() {
5122 _expand_heap_after_alloc_failure = true;
5123 _evacuation_failed = false;
5124
5125 // Disable the hot card cache.
5126 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5127 hot_card_cache->reset_hot_cache_claimed_index();
5128 hot_card_cache->set_use_cache(false);
5129
5130 }
5131
5132 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5133 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5134
5135 // Should G1EvacuationFailureALot be in effect for this GC?
5136 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5137
5138 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5139 double start_par_time_sec = os::elapsedTime();
5140 double end_par_time_sec;
5141
5142 {
5143 const uint n_workers = workers()->active_workers();
5144 G1RootProcessor root_processor(this, n_workers);
5145 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5146 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5147 if (collector_state()->during_initial_mark_pause()) {
5148 ClassLoaderDataGraph::clear_claimed_marks();
5149 }
5150
5151 // The individual threads will set their evac-failure closures.
5152 if (PrintTerminationStats) {
5153 print_termination_stats_hdr(gclog_or_tty);
5154 }
5155
5156 workers()->run_task(&g1_par_task);
5157 end_par_time_sec = os::elapsedTime();
5158
5159 // Closing the inner scope will execute the destructor
5160 // for the G1RootProcessor object. We record the current
5161 // elapsed time before closing the scope so that time
5162 // taken for the destructor is NOT included in the
5163 // reported parallel time.
5164 }
5165
5166 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5167
5168 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5169 phase_times->record_par_time(par_time_ms);
5170
5171 double code_root_fixup_time_ms =
5172 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5173 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5174
5175 // Process any discovered reference objects - we have
5176 // to do this _before_ we retire the GC alloc regions
5177 // as we may have to copy some 'reachable' referent
5178 // objects (and their reachable sub-graphs) that were
5179 // not copied during the pause.
5180 process_discovered_references(per_thread_states);
5181
5182 if (G1StringDedup::is_enabled()) {
5183 double fixup_start = os::elapsedTime();
5184
5185 G1STWIsAliveClosure is_alive(this);
5186 G1KeepAliveClosure keep_alive(this);
5187 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5188
5189 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5190 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5191 }
5192
5193 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5194
5195 if (evacuation_failed()) {
5196 remove_self_forwarding_pointers();
5197
5198 // Reset the G1EvacuationFailureALot counters and flags
5199 // Note: the values are reset only when an actual
5200 // evacuation failure occurs.
5201 NOT_PRODUCT(reset_evacuation_should_fail();)
5202 }
5203
5204 // Enqueue any remaining references remaining on the STW
5205 // reference processor's discovered lists. We need to do
5206 // this after the card table is cleaned (and verified) as
5207 // the act of enqueueing entries on to the pending list
5208 // will log these updates (and dirty their associated
5209 // cards). We need these updates logged to update any
5210 // RSets.
5211 enqueue_discovered_references(per_thread_states);
5212 }
5213
5214 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5215 _allocator->release_gc_alloc_regions(evacuation_info);
5216
5217 per_thread_states->flush();
5218
5219 record_obj_copy_mem_stats();
5220
5221 _survivor_evac_stats.adjust_desired_plab_sz();
5222 _old_evac_stats.adjust_desired_plab_sz();
5223
5224 // Reset and re-enable the hot card cache.
5225 // Note the counts for the cards in the regions in the
5226 // collection set are reset when the collection set is freed.
5227 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5228 hot_card_cache->reset_hot_cache();
5229 hot_card_cache->set_use_cache(true);
5230
5231 purge_code_root_memory();
5232
5233 redirty_logged_cards();
5234 #if defined(COMPILER2) || INCLUDE_JVMCI
5235 DerivedPointerTable::update_pointers();
5236 #endif
5237 }
5238
5239 void G1CollectedHeap::record_obj_copy_mem_stats() {
5240 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5241 create_g1_evac_summary(&_old_evac_stats));
5242 }
5243
5244 void G1CollectedHeap::free_region(HeapRegion* hr,
5245 FreeRegionList* free_list,
5246 bool par,
5247 bool locked) {
5248 assert(!hr->is_free(), "the region should not be free");
5249 assert(!hr->is_empty(), "the region should not be empty");
5250 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5251 assert(free_list != NULL, "pre-condition");
5252
5253 if (G1VerifyBitmaps) {
5254 MemRegion mr(hr->bottom(), hr->end());
5255 concurrent_mark()->clearRangePrevBitmap(mr);
5256 }
5257
5258 // Clear the card counts for this region.
5259 // Note: we only need to do this if the region is not young
5260 // (since we don't refine cards in young regions).
5261 if (!hr->is_young()) {
5262 _cg1r->hot_card_cache()->reset_card_counts(hr);
5263 }
5264 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5265 free_list->add_ordered(hr);
5266 }
5267
5268 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5269 FreeRegionList* free_list,
5270 bool par) {
5271 assert(hr->is_humongous(), "this is only for humongous regions");
5272 assert(free_list != NULL, "pre-condition");
5273 hr->clear_humongous();
5274 free_region(hr, free_list, par);
5275 }
5276
5277 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5278 const HeapRegionSetCount& humongous_regions_removed) {
5279 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5280 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5281 _old_set.bulk_remove(old_regions_removed);
5282 _humongous_set.bulk_remove(humongous_regions_removed);
5283 }
5284
5285 }
5286
5287 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5288 assert(list != NULL, "list can't be null");
5289 if (!list->is_empty()) {
5290 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5291 _hrm.insert_list_into_free_list(list);
5292 }
5293 }
5294
5295 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5296 decrease_used(bytes);
5297 }
5298
5299 class G1ParCleanupCTTask : public AbstractGangTask {
5300 G1SATBCardTableModRefBS* _ct_bs;
5301 G1CollectedHeap* _g1h;
5302 HeapRegion* volatile _su_head;
5303 public:
5304 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5305 G1CollectedHeap* g1h) :
5306 AbstractGangTask("G1 Par Cleanup CT Task"),
5307 _ct_bs(ct_bs), _g1h(g1h) { }
5308
5309 void work(uint worker_id) {
5310 HeapRegion* r;
5311 while (r = _g1h->pop_dirty_cards_region()) {
5312 clear_cards(r);
5313 }
5314 }
5315
5316 void clear_cards(HeapRegion* r) {
5317 // Cards of the survivors should have already been dirtied.
5318 if (!r->is_survivor()) {
5319 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5320 }
5321 }
5322 };
5323
5324 #ifndef PRODUCT
5325 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5326 G1CollectedHeap* _g1h;
5327 G1SATBCardTableModRefBS* _ct_bs;
5328 public:
5329 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5330 : _g1h(g1h), _ct_bs(ct_bs) { }
5331 virtual bool doHeapRegion(HeapRegion* r) {
5332 if (r->is_survivor()) {
5333 _g1h->verify_dirty_region(r);
5334 } else {
5335 _g1h->verify_not_dirty_region(r);
5336 }
5337 return false;
5338 }
5339 };
5340
5341 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5342 // All of the region should be clean.
5343 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5344 MemRegion mr(hr->bottom(), hr->end());
5345 ct_bs->verify_not_dirty_region(mr);
5346 }
5347
5348 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5349 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5350 // dirty allocated blocks as they allocate them. The thread that
5351 // retires each region and replaces it with a new one will do a
5352 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5353 // not dirty that area (one less thing to have to do while holding
5354 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5355 // is dirty.
5356 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5357 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5358 if (hr->is_young()) {
5359 ct_bs->verify_g1_young_region(mr);
5360 } else {
5361 ct_bs->verify_dirty_region(mr);
5362 }
5363 }
5364
5365 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5366 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5367 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5368 verify_dirty_region(hr);
5369 }
5370 }
5371
5372 void G1CollectedHeap::verify_dirty_young_regions() {
5373 verify_dirty_young_list(_young_list->first_region());
5374 }
5375
5376 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5377 HeapWord* tams, HeapWord* end) {
5378 guarantee(tams <= end,
5379 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5380 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5381 if (result < end) {
5382 gclog_or_tty->cr();
5383 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5384 bitmap_name, p2i(result));
5385 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5386 bitmap_name, p2i(tams), p2i(end));
5387 return false;
5388 }
5389 return true;
5390 }
5391
5392 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5393 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5394 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5395
5396 HeapWord* bottom = hr->bottom();
5397 HeapWord* ptams = hr->prev_top_at_mark_start();
5398 HeapWord* ntams = hr->next_top_at_mark_start();
5399 HeapWord* end = hr->end();
5400
5401 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5402
5403 bool res_n = true;
5404 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5405 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5406 // if we happen to be in that state.
5407 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5408 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5409 }
5410 if (!res_p || !res_n) {
5411 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5412 HR_FORMAT_PARAMS(hr));
5413 gclog_or_tty->print_cr("#### Caller: %s", caller);
5414 return false;
5415 }
5416 return true;
5417 }
5418
5419 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5420 if (!G1VerifyBitmaps) return;
5421
5422 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5423 }
5424
5425 class G1VerifyBitmapClosure : public HeapRegionClosure {
5426 private:
5427 const char* _caller;
5428 G1CollectedHeap* _g1h;
5429 bool _failures;
5430
5431 public:
5432 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5433 _caller(caller), _g1h(g1h), _failures(false) { }
5434
5435 bool failures() { return _failures; }
5436
5437 virtual bool doHeapRegion(HeapRegion* hr) {
5438 bool result = _g1h->verify_bitmaps(_caller, hr);
5439 if (!result) {
5440 _failures = true;
5441 }
5442 return false;
5443 }
5444 };
5445
5446 void G1CollectedHeap::check_bitmaps(const char* caller) {
5447 if (!G1VerifyBitmaps) return;
5448
5449 G1VerifyBitmapClosure cl(caller, this);
5450 heap_region_iterate(&cl);
5451 guarantee(!cl.failures(), "bitmap verification");
5452 }
5453
5454 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5455 private:
5456 bool _failures;
5457 public:
5458 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5459
5460 virtual bool doHeapRegion(HeapRegion* hr) {
5461 uint i = hr->hrm_index();
5462 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5463 if (hr->is_humongous()) {
5464 if (hr->in_collection_set()) {
5465 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5466 _failures = true;
5467 return true;
5468 }
5469 if (cset_state.is_in_cset()) {
5470 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5471 _failures = true;
5472 return true;
5473 }
5474 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5475 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5476 _failures = true;
5477 return true;
5478 }
5479 } else {
5480 if (cset_state.is_humongous()) {
5481 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5482 _failures = true;
5483 return true;
5484 }
5485 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5486 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5487 hr->in_collection_set(), cset_state.value(), i);
5488 _failures = true;
5489 return true;
5490 }
5491 if (cset_state.is_in_cset()) {
5492 if (hr->is_young() != (cset_state.is_young())) {
5493 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5494 hr->is_young(), cset_state.value(), i);
5495 _failures = true;
5496 return true;
5497 }
5498 if (hr->is_old() != (cset_state.is_old())) {
5499 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5500 hr->is_old(), cset_state.value(), i);
5501 _failures = true;
5502 return true;
5503 }
5504 }
5505 }
5506 return false;
5507 }
5508
5509 bool failures() const { return _failures; }
5510 };
5511
5512 bool G1CollectedHeap::check_cset_fast_test() {
5513 G1CheckCSetFastTableClosure cl;
5514 _hrm.iterate(&cl);
5515 return !cl.failures();
5516 }
5517 #endif // PRODUCT
5518
5519 void G1CollectedHeap::cleanUpCardTable() {
5520 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5521 double start = os::elapsedTime();
5522
5523 {
5524 // Iterate over the dirty cards region list.
5525 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5526
5527 workers()->run_task(&cleanup_task);
5528 #ifndef PRODUCT
5529 if (G1VerifyCTCleanup || VerifyAfterGC) {
5530 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5531 heap_region_iterate(&cleanup_verifier);
5532 }
5533 #endif
5534 }
5535
5536 double elapsed = os::elapsedTime() - start;
5537 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5538 }
5539
5540 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5541 size_t pre_used = 0;
5542 FreeRegionList local_free_list("Local List for CSet Freeing");
5543
5544 double young_time_ms = 0.0;
5545 double non_young_time_ms = 0.0;
5546
5547 // Since the collection set is a superset of the the young list,
5548 // all we need to do to clear the young list is clear its
5549 // head and length, and unlink any young regions in the code below
5550 _young_list->clear();
5551
5552 G1CollectorPolicy* policy = g1_policy();
5553
5554 double start_sec = os::elapsedTime();
5555 bool non_young = true;
5556
5557 HeapRegion* cur = cs_head;
5558 int age_bound = -1;
5559 size_t rs_lengths = 0;
5560
5561 while (cur != NULL) {
5562 assert(!is_on_master_free_list(cur), "sanity");
5563 if (non_young) {
5564 if (cur->is_young()) {
5565 double end_sec = os::elapsedTime();
5566 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5567 non_young_time_ms += elapsed_ms;
5568
5569 start_sec = os::elapsedTime();
5570 non_young = false;
5571 }
5572 } else {
5573 if (!cur->is_young()) {
5574 double end_sec = os::elapsedTime();
5575 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5576 young_time_ms += elapsed_ms;
5577
5578 start_sec = os::elapsedTime();
5579 non_young = true;
5580 }
5581 }
5582
5583 rs_lengths += cur->rem_set()->occupied_locked();
5584
5585 HeapRegion* next = cur->next_in_collection_set();
5586 assert(cur->in_collection_set(), "bad CS");
5587 cur->set_next_in_collection_set(NULL);
5588 clear_in_cset(cur);
5589
5590 if (cur->is_young()) {
5591 int index = cur->young_index_in_cset();
5592 assert(index != -1, "invariant");
5593 assert((uint) index < policy->young_cset_region_length(), "invariant");
5594 size_t words_survived = surviving_young_words[index];
5595 cur->record_surv_words_in_group(words_survived);
5596
5597 // At this point the we have 'popped' cur from the collection set
5598 // (linked via next_in_collection_set()) but it is still in the
5599 // young list (linked via next_young_region()). Clear the
5600 // _next_young_region field.
5601 cur->set_next_young_region(NULL);
5602 } else {
5603 int index = cur->young_index_in_cset();
5604 assert(index == -1, "invariant");
5605 }
5606
5607 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5608 (!cur->is_young() && cur->young_index_in_cset() == -1),
5609 "invariant" );
5610
5611 if (!cur->evacuation_failed()) {
5612 MemRegion used_mr = cur->used_region();
5613
5614 // And the region is empty.
5615 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5616 pre_used += cur->used();
5617 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5618 } else {
5619 cur->uninstall_surv_rate_group();
5620 if (cur->is_young()) {
5621 cur->set_young_index_in_cset(-1);
5622 }
5623 cur->set_evacuation_failed(false);
5624 // The region is now considered to be old.
5625 cur->set_old();
5626 // Do some allocation statistics accounting. Regions that failed evacuation
5627 // are always made old, so there is no need to update anything in the young
5628 // gen statistics, but we need to update old gen statistics.
5629 size_t used_words = cur->marked_bytes() / HeapWordSize;
5630 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5631 _old_set.add(cur);
5632 evacuation_info.increment_collectionset_used_after(cur->used());
5633 }
5634 cur = next;
5635 }
5636
5637 evacuation_info.set_regions_freed(local_free_list.length());
5638 policy->record_max_rs_lengths(rs_lengths);
5639 policy->cset_regions_freed();
5640
5641 double end_sec = os::elapsedTime();
5642 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5643
5644 if (non_young) {
5645 non_young_time_ms += elapsed_ms;
5646 } else {
5647 young_time_ms += elapsed_ms;
5648 }
5649
5650 prepend_to_freelist(&local_free_list);
5651 decrement_summary_bytes(pre_used);
5652 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5653 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5654 }
5655
5656 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5657 private:
5658 FreeRegionList* _free_region_list;
5659 HeapRegionSet* _proxy_set;
5660 HeapRegionSetCount _humongous_regions_removed;
5661 size_t _freed_bytes;
5662 public:
5663
5664 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5665 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5666 }
5667
5668 virtual bool doHeapRegion(HeapRegion* r) {
5669 if (!r->is_starts_humongous()) {
5670 return false;
5671 }
5672
5673 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5674
5675 oop obj = (oop)r->bottom();
5676 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5677
5678 // The following checks whether the humongous object is live are sufficient.
5679 // The main additional check (in addition to having a reference from the roots
5680 // or the young gen) is whether the humongous object has a remembered set entry.
5681 //
5682 // A humongous object cannot be live if there is no remembered set for it
5683 // because:
5684 // - there can be no references from within humongous starts regions referencing
5685 // the object because we never allocate other objects into them.
5686 // (I.e. there are no intra-region references that may be missed by the
5687 // remembered set)
5688 // - as soon there is a remembered set entry to the humongous starts region
5689 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5690 // until the end of a concurrent mark.
5691 //
5692 // It is not required to check whether the object has been found dead by marking
5693 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5694 // all objects allocated during that time are considered live.
5695 // SATB marking is even more conservative than the remembered set.
5696 // So if at this point in the collection there is no remembered set entry,
5697 // nobody has a reference to it.
5698 // At the start of collection we flush all refinement logs, and remembered sets
5699 // are completely up-to-date wrt to references to the humongous object.
5700 //
5701 // Other implementation considerations:
5702 // - never consider object arrays at this time because they would pose
5703 // considerable effort for cleaning up the the remembered sets. This is
5704 // required because stale remembered sets might reference locations that
5705 // are currently allocated into.
5706 uint region_idx = r->hrm_index();
5707 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5708 !r->rem_set()->is_empty()) {
5709
5710 if (G1TraceEagerReclaimHumongousObjects) {
5711 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",
5712 region_idx,
5713 (size_t)obj->size() * HeapWordSize,
5714 p2i(r->bottom()),
5715 r->rem_set()->occupied(),
5716 r->rem_set()->strong_code_roots_list_length(),
5717 next_bitmap->isMarked(r->bottom()),
5718 g1h->is_humongous_reclaim_candidate(region_idx),
5719 obj->is_typeArray()
5720 );
5721 }
5722
5723 return false;
5724 }
5725
5726 guarantee(obj->is_typeArray(),
5727 "Only eagerly reclaiming type arrays is supported, but the object "
5728 PTR_FORMAT " is not.", p2i(r->bottom()));
5729
5730 if (G1TraceEagerReclaimHumongousObjects) {
5731 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",
5732 region_idx,
5733 (size_t)obj->size() * HeapWordSize,
5734 p2i(r->bottom()),
5735 r->rem_set()->occupied(),
5736 r->rem_set()->strong_code_roots_list_length(),
5737 next_bitmap->isMarked(r->bottom()),
5738 g1h->is_humongous_reclaim_candidate(region_idx),
5739 obj->is_typeArray()
5740 );
5741 }
5742 // Need to clear mark bit of the humongous object if already set.
5743 if (next_bitmap->isMarked(r->bottom())) {
5744 next_bitmap->clear(r->bottom());
5745 }
5746 do {
5747 HeapRegion* next = g1h->next_region_in_humongous(r);
5748 _freed_bytes += r->used();
5749 r->set_containing_set(NULL);
5750 _humongous_regions_removed.increment(1u, r->capacity());
5751 g1h->free_humongous_region(r, _free_region_list, false);
5752 r = next;
5753 } while (r != NULL);
5754
5755 return false;
5756 }
5757
5758 HeapRegionSetCount& humongous_free_count() {
5759 return _humongous_regions_removed;
5760 }
5761
5762 size_t bytes_freed() const {
5763 return _freed_bytes;
5764 }
5765
5766 size_t humongous_reclaimed() const {
5767 return _humongous_regions_removed.length();
5768 }
5769 };
5770
5771 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5772 assert_at_safepoint(true);
5773
5774 if (!G1EagerReclaimHumongousObjects ||
5775 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5776 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5777 return;
5778 }
5779
5780 double start_time = os::elapsedTime();
5781
5782 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5783
5784 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5785 heap_region_iterate(&cl);
5786
5787 HeapRegionSetCount empty_set;
5788 remove_from_old_sets(empty_set, cl.humongous_free_count());
5789
5790 G1HRPrinter* hrp = hr_printer();
5791 if (hrp->is_active()) {
5792 FreeRegionListIterator iter(&local_cleanup_list);
5793 while (iter.more_available()) {
5794 HeapRegion* hr = iter.get_next();
5795 hrp->cleanup(hr);
5796 }
5797 }
5798
5799 prepend_to_freelist(&local_cleanup_list);
5800 decrement_summary_bytes(cl.bytes_freed());
5801
5802 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5803 cl.humongous_reclaimed());
5804 }
5805
5806 // This routine is similar to the above but does not record
5807 // any policy statistics or update free lists; we are abandoning
5808 // the current incremental collection set in preparation of a
5809 // full collection. After the full GC we will start to build up
5810 // the incremental collection set again.
5811 // This is only called when we're doing a full collection
5812 // and is immediately followed by the tearing down of the young list.
5813
5814 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5815 HeapRegion* cur = cs_head;
5816
5817 while (cur != NULL) {
5818 HeapRegion* next = cur->next_in_collection_set();
5819 assert(cur->in_collection_set(), "bad CS");
5820 cur->set_next_in_collection_set(NULL);
5821 clear_in_cset(cur);
5822 cur->set_young_index_in_cset(-1);
5823 cur = next;
5824 }
5825 }
5826
5827 void G1CollectedHeap::set_free_regions_coming() {
5828 if (G1ConcRegionFreeingVerbose) {
5829 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5830 "setting free regions coming");
5831 }
5832
5833 assert(!free_regions_coming(), "pre-condition");
5834 _free_regions_coming = true;
5835 }
5836
5837 void G1CollectedHeap::reset_free_regions_coming() {
5838 assert(free_regions_coming(), "pre-condition");
5839
5840 {
5841 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5842 _free_regions_coming = false;
5843 SecondaryFreeList_lock->notify_all();
5844 }
5845
5846 if (G1ConcRegionFreeingVerbose) {
5847 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5848 "reset free regions coming");
5849 }
5850 }
5851
5852 void G1CollectedHeap::wait_while_free_regions_coming() {
5853 // Most of the time we won't have to wait, so let's do a quick test
5854 // first before we take the lock.
5855 if (!free_regions_coming()) {
5856 return;
5857 }
5858
5859 if (G1ConcRegionFreeingVerbose) {
5860 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5861 "waiting for free regions");
5862 }
5863
5864 {
5865 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5866 while (free_regions_coming()) {
5867 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5868 }
5869 }
5870
5871 if (G1ConcRegionFreeingVerbose) {
5872 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5873 "done waiting for free regions");
5874 }
5875 }
5876
5877 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5878 return _allocator->is_retained_old_region(hr);
5879 }
5880
5881 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5882 _young_list->push_region(hr);
5883 }
5884
5885 class NoYoungRegionsClosure: public HeapRegionClosure {
5886 private:
5887 bool _success;
5888 public:
5889 NoYoungRegionsClosure() : _success(true) { }
5890 bool doHeapRegion(HeapRegion* r) {
5891 if (r->is_young()) {
5892 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5893 p2i(r->bottom()), p2i(r->end()));
5894 _success = false;
5895 }
5896 return false;
5897 }
5898 bool success() { return _success; }
5899 };
5900
5901 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5902 bool ret = _young_list->check_list_empty(check_sample);
5903
5904 if (check_heap) {
5905 NoYoungRegionsClosure closure;
5906 heap_region_iterate(&closure);
5907 ret = ret && closure.success();
5908 }
5909
5910 return ret;
5911 }
5912
5913 class TearDownRegionSetsClosure : public HeapRegionClosure {
5914 private:
5915 HeapRegionSet *_old_set;
5916
5917 public:
5918 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5919
5920 bool doHeapRegion(HeapRegion* r) {
5921 if (r->is_old()) {
5922 _old_set->remove(r);
5923 } else {
5924 // We ignore free regions, we'll empty the free list afterwards.
5925 // We ignore young regions, we'll empty the young list afterwards.
5926 // We ignore humongous regions, we're not tearing down the
5927 // humongous regions set.
5928 assert(r->is_free() || r->is_young() || r->is_humongous(),
5929 "it cannot be another type");
5930 }
5931 return false;
5932 }
5933
5934 ~TearDownRegionSetsClosure() {
5935 assert(_old_set->is_empty(), "post-condition");
5936 }
5937 };
5938
5939 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5940 assert_at_safepoint(true /* should_be_vm_thread */);
5941
5942 if (!free_list_only) {
5943 TearDownRegionSetsClosure cl(&_old_set);
5944 heap_region_iterate(&cl);
5945
5946 // Note that emptying the _young_list is postponed and instead done as
5947 // the first step when rebuilding the regions sets again. The reason for
5948 // this is that during a full GC string deduplication needs to know if
5949 // a collected region was young or old when the full GC was initiated.
5950 }
5951 _hrm.remove_all_free_regions();
5952 }
5953
5954 void G1CollectedHeap::increase_used(size_t bytes) {
5955 _summary_bytes_used += bytes;
5956 }
5957
5958 void G1CollectedHeap::decrease_used(size_t bytes) {
5959 assert(_summary_bytes_used >= bytes,
5960 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5961 _summary_bytes_used, bytes);
5962 _summary_bytes_used -= bytes;
5963 }
5964
5965 void G1CollectedHeap::set_used(size_t bytes) {
5966 _summary_bytes_used = bytes;
5967 }
5968
5969 class RebuildRegionSetsClosure : public HeapRegionClosure {
5970 private:
5971 bool _free_list_only;
5972 HeapRegionSet* _old_set;
5973 HeapRegionManager* _hrm;
5974 size_t _total_used;
5975
5976 public:
5977 RebuildRegionSetsClosure(bool free_list_only,
5978 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5979 _free_list_only(free_list_only),
5980 _old_set(old_set), _hrm(hrm), _total_used(0) {
5981 assert(_hrm->num_free_regions() == 0, "pre-condition");
5982 if (!free_list_only) {
5983 assert(_old_set->is_empty(), "pre-condition");
5984 }
5985 }
5986
5987 bool doHeapRegion(HeapRegion* r) {
5988 if (r->is_empty()) {
5989 // Add free regions to the free list
5990 r->set_free();
5991 r->set_allocation_context(AllocationContext::system());
5992 _hrm->insert_into_free_list(r);
5993 } else if (!_free_list_only) {
5994 assert(!r->is_young(), "we should not come across young regions");
5995
5996 if (r->is_humongous()) {
5997 // We ignore humongous regions. We left the humongous set unchanged.
5998 } else {
5999 // Objects that were compacted would have ended up on regions
6000 // that were previously old or free. Archive regions (which are
6001 // old) will not have been touched.
6002 assert(r->is_free() || r->is_old(), "invariant");
6003 // We now consider them old, so register as such. Leave
6004 // archive regions set that way, however, while still adding
6005 // them to the old set.
6006 if (!r->is_archive()) {
6007 r->set_old();
6008 }
6009 _old_set->add(r);
6010 }
6011 _total_used += r->used();
6012 }
6013
6014 return false;
6015 }
6016
6017 size_t total_used() {
6018 return _total_used;
6019 }
6020 };
6021
6022 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6023 assert_at_safepoint(true /* should_be_vm_thread */);
6024
6025 if (!free_list_only) {
6026 _young_list->empty_list();
6027 }
6028
6029 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6030 heap_region_iterate(&cl);
6031
6032 if (!free_list_only) {
6033 set_used(cl.total_used());
6034 if (_archive_allocator != NULL) {
6035 _archive_allocator->clear_used();
6036 }
6037 }
6038 assert(used_unlocked() == recalculate_used(),
6039 "inconsistent used_unlocked(), "
6040 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6041 used_unlocked(), recalculate_used());
6042 }
6043
6044 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6045 _refine_cte_cl->set_concurrent(concurrent);
6046 }
6047
6048 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6049 HeapRegion* hr = heap_region_containing(p);
6050 return hr->is_in(p);
6051 }
6052
6053 // Methods for the mutator alloc region
6054
6055 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6056 bool force) {
6057 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6058 assert(!force || g1_policy()->can_expand_young_list(),
6059 "if force is true we should be able to expand the young list");
6060 bool young_list_full = g1_policy()->is_young_list_full();
6061 if (force || !young_list_full) {
6062 HeapRegion* new_alloc_region = new_region(word_size,
6063 false /* is_old */,
6064 false /* do_expand */);
6065 if (new_alloc_region != NULL) {
6066 set_region_short_lived_locked(new_alloc_region);
6067 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6068 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6069 return new_alloc_region;
6070 }
6071 }
6072 return NULL;
6073 }
6074
6075 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6076 size_t allocated_bytes) {
6077 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6078 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6079
6080 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6081 increase_used(allocated_bytes);
6082 _hr_printer.retire(alloc_region);
6083 // We update the eden sizes here, when the region is retired,
6084 // instead of when it's allocated, since this is the point that its
6085 // used space has been recored in _summary_bytes_used.
6086 g1mm()->update_eden_size();
6087 }
6088
6089 // Methods for the GC alloc regions
6090
6091 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6092 uint count,
6093 InCSetState dest) {
6094 assert(FreeList_lock->owned_by_self(), "pre-condition");
6095
6096 if (count < g1_policy()->max_regions(dest)) {
6097 const bool is_survivor = (dest.is_young());
6098 HeapRegion* new_alloc_region = new_region(word_size,
6099 !is_survivor,
6100 true /* do_expand */);
6101 if (new_alloc_region != NULL) {
6102 // We really only need to do this for old regions given that we
6103 // should never scan survivors. But it doesn't hurt to do it
6104 // for survivors too.
6105 new_alloc_region->record_timestamp();
6106 if (is_survivor) {
6107 new_alloc_region->set_survivor();
6108 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6109 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6110 } else {
6111 new_alloc_region->set_old();
6112 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6113 check_bitmaps("Old Region Allocation", new_alloc_region);
6114 }
6115 bool during_im = collector_state()->during_initial_mark_pause();
6116 new_alloc_region->note_start_of_copying(during_im);
6117 return new_alloc_region;
6118 }
6119 }
6120 return NULL;
6121 }
6122
6123 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6124 size_t allocated_bytes,
6125 InCSetState dest) {
6126 bool during_im = collector_state()->during_initial_mark_pause();
6127 alloc_region->note_end_of_copying(during_im);
6128 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6129 if (dest.is_young()) {
6130 young_list()->add_survivor_region(alloc_region);
6131 } else {
6132 _old_set.add(alloc_region);
6133 }
6134 _hr_printer.retire(alloc_region);
6135 }
6136
6137 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6138 bool expanded = false;
6139 uint index = _hrm.find_highest_free(&expanded);
6140
6141 if (index != G1_NO_HRM_INDEX) {
6142 if (expanded) {
6143 ergo_verbose1(ErgoHeapSizing,
6144 "attempt heap expansion",
6145 ergo_format_reason("requested address range outside heap bounds")
6146 ergo_format_byte("region size"),
6147 HeapRegion::GrainWords * HeapWordSize);
6148 }
6149 _hrm.allocate_free_regions_starting_at(index, 1);
6150 return region_at(index);
6151 }
6152 return NULL;
6153 }
6154
6155 // Heap region set verification
6156
6157 class VerifyRegionListsClosure : public HeapRegionClosure {
6158 private:
6159 HeapRegionSet* _old_set;
6160 HeapRegionSet* _humongous_set;
6161 HeapRegionManager* _hrm;
6162
6163 public:
6164 HeapRegionSetCount _old_count;
6165 HeapRegionSetCount _humongous_count;
6166 HeapRegionSetCount _free_count;
6167
6168 VerifyRegionListsClosure(HeapRegionSet* old_set,
6169 HeapRegionSet* humongous_set,
6170 HeapRegionManager* hrm) :
6171 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6172 _old_count(), _humongous_count(), _free_count(){ }
6173
6174 bool doHeapRegion(HeapRegion* hr) {
6175 if (hr->is_young()) {
6176 // TODO
6177 } else if (hr->is_humongous()) {
6178 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6179 _humongous_count.increment(1u, hr->capacity());
6180 } else if (hr->is_empty()) {
6181 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6182 _free_count.increment(1u, hr->capacity());
6183 } else if (hr->is_old()) {
6184 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6185 _old_count.increment(1u, hr->capacity());
6186 } else {
6187 // There are no other valid region types. Check for one invalid
6188 // one we can identify: pinned without old or humongous set.
6189 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6190 ShouldNotReachHere();
6191 }
6192 return false;
6193 }
6194
6195 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6196 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6197 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6198 old_set->total_capacity_bytes(), _old_count.capacity());
6199
6200 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6201 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6202 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6203
6204 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());
6205 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6206 free_list->total_capacity_bytes(), _free_count.capacity());
6207 }
6208 };
6209
6210 void G1CollectedHeap::verify_region_sets() {
6211 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6212
6213 // First, check the explicit lists.
6214 _hrm.verify();
6215 {
6216 // Given that a concurrent operation might be adding regions to
6217 // the secondary free list we have to take the lock before
6218 // verifying it.
6219 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6220 _secondary_free_list.verify_list();
6221 }
6222
6223 // If a concurrent region freeing operation is in progress it will
6224 // be difficult to correctly attributed any free regions we come
6225 // across to the correct free list given that they might belong to
6226 // one of several (free_list, secondary_free_list, any local lists,
6227 // etc.). So, if that's the case we will skip the rest of the
6228 // verification operation. Alternatively, waiting for the concurrent
6229 // operation to complete will have a non-trivial effect on the GC's
6230 // operation (no concurrent operation will last longer than the
6231 // interval between two calls to verification) and it might hide
6232 // any issues that we would like to catch during testing.
6233 if (free_regions_coming()) {
6234 return;
6235 }
6236
6237 // Make sure we append the secondary_free_list on the free_list so
6238 // that all free regions we will come across can be safely
6239 // attributed to the free_list.
6240 append_secondary_free_list_if_not_empty_with_lock();
6241
6242 // Finally, make sure that the region accounting in the lists is
6243 // consistent with what we see in the heap.
6244
6245 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6246 heap_region_iterate(&cl);
6247 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6248 }
6249
6250 // Optimized nmethod scanning
6251
6252 class RegisterNMethodOopClosure: public OopClosure {
6253 G1CollectedHeap* _g1h;
6254 nmethod* _nm;
6255
6256 template <class T> void do_oop_work(T* p) {
6257 T heap_oop = oopDesc::load_heap_oop(p);
6258 if (!oopDesc::is_null(heap_oop)) {
6259 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6260 HeapRegion* hr = _g1h->heap_region_containing(obj);
6261 assert(!hr->is_continues_humongous(),
6262 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6263 " starting at " HR_FORMAT,
6264 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6265
6266 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6267 hr->add_strong_code_root_locked(_nm);
6268 }
6269 }
6270
6271 public:
6272 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6273 _g1h(g1h), _nm(nm) {}
6274
6275 void do_oop(oop* p) { do_oop_work(p); }
6276 void do_oop(narrowOop* p) { do_oop_work(p); }
6277 };
6278
6279 class UnregisterNMethodOopClosure: public OopClosure {
6280 G1CollectedHeap* _g1h;
6281 nmethod* _nm;
6282
6283 template <class T> void do_oop_work(T* p) {
6284 T heap_oop = oopDesc::load_heap_oop(p);
6285 if (!oopDesc::is_null(heap_oop)) {
6286 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6287 HeapRegion* hr = _g1h->heap_region_containing(obj);
6288 assert(!hr->is_continues_humongous(),
6289 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6290 " starting at " HR_FORMAT,
6291 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6292
6293 hr->remove_strong_code_root(_nm);
6294 }
6295 }
6296
6297 public:
6298 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6299 _g1h(g1h), _nm(nm) {}
6300
6301 void do_oop(oop* p) { do_oop_work(p); }
6302 void do_oop(narrowOop* p) { do_oop_work(p); }
6303 };
6304
6305 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6306 CollectedHeap::register_nmethod(nm);
6307
6308 guarantee(nm != NULL, "sanity");
6309 RegisterNMethodOopClosure reg_cl(this, nm);
6310 nm->oops_do(®_cl);
6311 }
6312
6313 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6314 CollectedHeap::unregister_nmethod(nm);
6315
6316 guarantee(nm != NULL, "sanity");
6317 UnregisterNMethodOopClosure reg_cl(this, nm);
6318 nm->oops_do(®_cl, true);
6319 }
6320
6321 void G1CollectedHeap::purge_code_root_memory() {
6322 double purge_start = os::elapsedTime();
6323 G1CodeRootSet::purge();
6324 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6325 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6326 }
6327
6328 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6329 G1CollectedHeap* _g1h;
6330
6331 public:
6332 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6333 _g1h(g1h) {}
6334
6335 void do_code_blob(CodeBlob* cb) {
6336 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6337 if (nm == NULL) {
6338 return;
6339 }
6340
6341 if (ScavengeRootsInCode) {
6342 _g1h->register_nmethod(nm);
6343 }
6344 }
6345 };
6346
6347 void G1CollectedHeap::rebuild_strong_code_roots() {
6348 RebuildStrongCodeRootClosure blob_cl(this);
6349 CodeCache::blobs_do(&blob_cl);
6350 }