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