1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootClosures.hpp"
48 #include "gc/g1/g1RootProcessor.hpp"
49 #include "gc/g1/g1StringDedup.hpp"
50 #include "gc/g1/g1YCTypes.hpp"
51 #include "gc/g1/heapRegion.inline.hpp"
52 #include "gc/g1/heapRegionRemSet.hpp"
53 #include "gc/g1/heapRegionSet.inline.hpp"
54 #include "gc/g1/suspendibleThreadSet.hpp"
55 #include "gc/g1/vm_operations_g1.hpp"
56 #include "gc/shared/gcHeapSummary.hpp"
57 #include "gc/shared/gcId.hpp"
58 #include "gc/shared/gcLocker.inline.hpp"
59 #include "gc/shared/gcTimer.hpp"
60 #include "gc/shared/gcTrace.hpp"
61 #include "gc/shared/gcTraceTime.hpp"
62 #include "gc/shared/generationSpec.hpp"
63 #include "gc/shared/isGCActiveMark.hpp"
64 #include "gc/shared/referenceProcessor.hpp"
65 #include "gc/shared/taskqueue.inline.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_processed;
116
117 public:
118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
119
120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
121 *card_ptr = CardTableModRefBS::dirty_card_val();
122 _num_processed++;
123 return true;
124 }
125
126 size_t num_processed() const { return _num_processed; }
127 };
128
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
141 {
142 // Claim the right to put the region on the dirty cards region list
143 // by installing a self pointer.
144 HeapRegion* next = hr->get_next_dirty_cards_region();
145 if (next == NULL) {
146 HeapRegion* res = (HeapRegion*)
147 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
148 NULL);
149 if (res == NULL) {
150 HeapRegion* head;
151 do {
152 // Put the region to the dirty cards region list.
153 head = _dirty_cards_region_list;
154 next = (HeapRegion*)
155 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
156 if (next == head) {
157 assert(hr->get_next_dirty_cards_region() == hr,
158 "hr->get_next_dirty_cards_region() != hr");
159 if (next == NULL) {
160 // The last region in the list points to itself.
161 hr->set_next_dirty_cards_region(hr);
162 } else {
163 hr->set_next_dirty_cards_region(next);
164 }
165 }
166 } while (next != head);
167 }
168 }
169 }
170
171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
172 {
173 HeapRegion* head;
174 HeapRegion* hr;
175 do {
176 head = _dirty_cards_region_list;
177 if (head == NULL) {
178 return NULL;
179 }
180 HeapRegion* new_head = head->get_next_dirty_cards_region();
181 if (head == new_head) {
182 // The last region.
183 new_head = NULL;
184 }
185 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
186 head);
187 } while (hr != head);
188 assert(hr != NULL, "invariant");
189 hr->set_next_dirty_cards_region(NULL);
190 return hr;
191 }
192
193 // Returns true if the reference points to an object that
194 // can move in an incremental collection.
195 bool G1CollectedHeap::is_scavengable(const void* p) {
196 HeapRegion* hr = heap_region_containing(p);
197 return !hr->is_pinned();
198 }
199
200 // Private methods.
201
202 HeapRegion*
203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
205 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
206 if (!_secondary_free_list.is_empty()) {
207 if (G1ConcRegionFreeingVerbose) {
208 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
209 "secondary_free_list has %u entries",
210 _secondary_free_list.length());
211 }
212 // It looks as if there are free regions available on the
213 // secondary_free_list. Let's move them to the free_list and try
214 // again to allocate from it.
215 append_secondary_free_list();
216
217 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
218 "empty we should have moved at least one entry to the free_list");
219 HeapRegion* res = _hrm.allocate_free_region(is_old);
220 if (G1ConcRegionFreeingVerbose) {
221 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
222 "allocated " HR_FORMAT " from secondary_free_list",
223 HR_FORMAT_PARAMS(res));
224 }
225 return res;
226 }
227
228 // Wait here until we get notified either when (a) there are no
229 // more free regions coming or (b) some regions have been moved on
230 // the secondary_free_list.
231 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
232 }
233
234 if (G1ConcRegionFreeingVerbose) {
235 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
236 "could not allocate from secondary_free_list");
237 }
238 return NULL;
239 }
240
241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
242 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
243 "the only time we use this to allocate a humongous region is "
244 "when we are allocating a single humongous region");
245
246 HeapRegion* res;
247 if (G1StressConcRegionFreeing) {
248 if (!_secondary_free_list.is_empty()) {
249 if (G1ConcRegionFreeingVerbose) {
250 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
251 "forced to look at the secondary_free_list");
252 }
253 res = new_region_try_secondary_free_list(is_old);
254 if (res != NULL) {
255 return res;
256 }
257 }
258 }
259
260 res = _hrm.allocate_free_region(is_old);
261
262 if (res == NULL) {
263 if (G1ConcRegionFreeingVerbose) {
264 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
265 "res == NULL, trying the secondary_free_list");
266 }
267 res = new_region_try_secondary_free_list(is_old);
268 }
269 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
270 // Currently, only attempts to allocate GC alloc regions set
271 // do_expand to true. So, we should only reach here during a
272 // safepoint. If this assumption changes we might have to
273 // reconsider the use of _expand_heap_after_alloc_failure.
274 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
275
276 ergo_verbose1(ErgoHeapSizing,
277 "attempt heap expansion",
278 ergo_format_reason("region allocation request failed")
279 ergo_format_byte("allocation request"),
280 word_size * HeapWordSize);
281 if (expand(word_size * HeapWordSize)) {
282 // Given that expand() succeeded in expanding the heap, and we
283 // always expand the heap by an amount aligned to the heap
284 // region size, the free list should in theory not be empty.
285 // In either case allocate_free_region() will check for NULL.
286 res = _hrm.allocate_free_region(is_old);
287 } else {
288 _expand_heap_after_alloc_failure = false;
289 }
290 }
291 return res;
292 }
293
294 HeapWord*
295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
296 uint num_regions,
297 size_t word_size,
298 AllocationContext_t context) {
299 assert(first != G1_NO_HRM_INDEX, "pre-condition");
300 assert(is_humongous(word_size), "word_size should be humongous");
301 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
302
303 // Index of last region in the series + 1.
304 uint last = first + num_regions;
305
306 // We need to initialize the region(s) we just discovered. This is
307 // a bit tricky given that it can happen concurrently with
308 // refinement threads refining cards on these regions and
309 // potentially wanting to refine the BOT as they are scanning
310 // those cards (this can happen shortly after a cleanup; see CR
311 // 6991377). So we have to set up the region(s) carefully and in
312 // a specific order.
313
314 // The word size sum of all the regions we will allocate.
315 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
316 assert(word_size <= word_size_sum, "sanity");
317
318 // This will be the "starts humongous" region.
319 HeapRegion* first_hr = region_at(first);
320 // The header of the new object will be placed at the bottom of
321 // the first region.
322 HeapWord* new_obj = first_hr->bottom();
323 // This will be the new top of the new object.
324 HeapWord* obj_top = new_obj + word_size;
325
326 // First, we need to zero the header of the space that we will be
327 // allocating. When we update top further down, some refinement
328 // threads might try to scan the region. By zeroing the header we
329 // ensure that any thread that will try to scan the region will
330 // come across the zero klass word and bail out.
331 //
332 // NOTE: It would not have been correct to have used
333 // CollectedHeap::fill_with_object() and make the space look like
334 // an int array. The thread that is doing the allocation will
335 // later update the object header to a potentially different array
336 // type and, for a very short period of time, the klass and length
337 // fields will be inconsistent. This could cause a refinement
338 // thread to calculate the object size incorrectly.
339 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
340
341 // We will set up the first region as "starts humongous". This
342 // will also update the BOT covering all the regions to reflect
343 // that there is a single object that starts at the bottom of the
344 // first region.
345 first_hr->set_starts_humongous(obj_top);
346 first_hr->set_allocation_context(context);
347 // Then, if there are any, we will set up the "continues
348 // humongous" regions.
349 HeapRegion* hr = NULL;
350 for (uint i = first + 1; i < last; ++i) {
351 hr = region_at(i);
352 hr->set_continues_humongous(first_hr);
353 hr->set_allocation_context(context);
354 }
355
356 // Up to this point no concurrent thread would have been able to
357 // do any scanning on any region in this series. All the top
358 // fields still point to bottom, so the intersection between
359 // [bottom,top] and [card_start,card_end] will be empty. Before we
360 // update the top fields, we'll do a storestore to make sure that
361 // no thread sees the update to top before the zeroing of the
362 // object header and the BOT initialization.
363 OrderAccess::storestore();
364
365 // Now that the BOT and the object header have been initialized,
366 // we can update top of the "starts humongous" region.
367 first_hr->set_top(MIN2(first_hr->end(), obj_top));
368 if (_hr_printer.is_active()) {
369 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
370 }
371
372 // Now, we will update the top fields of the "continues humongous"
373 // regions.
374 hr = NULL;
375 for (uint i = first + 1; i < last; ++i) {
376 hr = region_at(i);
377 if ((i + 1) == last) {
378 // last continues humongous region
379 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
380 "new_top should fall on this region");
381 hr->set_top(obj_top);
382 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
383 } else {
384 // not last one
385 assert(obj_top > hr->end(), "obj_top should be above this region");
386 hr->set_top(hr->end());
387 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
388 }
389 }
390 // If we have continues humongous regions (hr != NULL), its top should
391 // match obj_top.
392 assert(hr == NULL || (hr->top() == obj_top), "sanity");
393 check_bitmaps("Humongous Region Allocation", first_hr);
394
395 increase_used(word_size * HeapWordSize);
396
397 for (uint i = first; i < last; ++i) {
398 _humongous_set.add(region_at(i));
399 }
400
401 return new_obj;
402 }
403
404 // If could fit into free regions w/o expansion, try.
405 // Otherwise, if can expand, do so.
406 // Otherwise, if using ex regions might help, try with ex given back.
407 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
408 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
409
410 verify_region_sets_optional();
411
412 uint first = G1_NO_HRM_INDEX;
413 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
414
415 if (obj_regions == 1) {
416 // Only one region to allocate, try to use a fast path by directly allocating
417 // from the free lists. Do not try to expand here, we will potentially do that
418 // later.
419 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
420 if (hr != NULL) {
421 first = hr->hrm_index();
422 }
423 } else {
424 // We can't allocate humongous regions spanning more than one region while
425 // cleanupComplete() is running, since some of the regions we find to be
426 // empty might not yet be added to the free list. It is not straightforward
427 // to know in which list they are on so that we can remove them. We only
428 // need to do this if we need to allocate more than one region to satisfy the
429 // current humongous allocation request. If we are only allocating one region
430 // we use the one-region region allocation code (see above), that already
431 // potentially waits for regions from the secondary free list.
432 wait_while_free_regions_coming();
433 append_secondary_free_list_if_not_empty_with_lock();
434
435 // Policy: Try only empty regions (i.e. already committed first). Maybe we
436 // are lucky enough to find some.
437 first = _hrm.find_contiguous_only_empty(obj_regions);
438 if (first != G1_NO_HRM_INDEX) {
439 _hrm.allocate_free_regions_starting_at(first, obj_regions);
440 }
441 }
442
443 if (first == G1_NO_HRM_INDEX) {
444 // Policy: We could not find enough regions for the humongous object in the
445 // free list. Look through the heap to find a mix of free and uncommitted regions.
446 // If so, try expansion.
447 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
448 if (first != G1_NO_HRM_INDEX) {
449 // We found something. Make sure these regions are committed, i.e. expand
450 // the heap. Alternatively we could do a defragmentation GC.
451 ergo_verbose1(ErgoHeapSizing,
452 "attempt heap expansion",
453 ergo_format_reason("humongous allocation request failed")
454 ergo_format_byte("allocation request"),
455 word_size * HeapWordSize);
456
457 _hrm.expand_at(first, obj_regions);
458 g1_policy()->record_new_heap_size(num_regions());
459
460 #ifdef ASSERT
461 for (uint i = first; i < first + obj_regions; ++i) {
462 HeapRegion* hr = region_at(i);
463 assert(hr->is_free(), "sanity");
464 assert(hr->is_empty(), "sanity");
465 assert(is_on_master_free_list(hr), "sanity");
466 }
467 #endif
468 _hrm.allocate_free_regions_starting_at(first, obj_regions);
469 } else {
470 // Policy: Potentially trigger a defragmentation GC.
471 }
472 }
473
474 HeapWord* result = NULL;
475 if (first != G1_NO_HRM_INDEX) {
476 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
477 word_size, context);
478 assert(result != NULL, "it should always return a valid result");
479
480 // A successful humongous object allocation changes the used space
481 // information of the old generation so we need to recalculate the
482 // sizes and update the jstat counters here.
483 g1mm()->update_sizes();
484 }
485
486 verify_region_sets_optional();
487
488 return result;
489 }
490
491 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
492 assert_heap_not_locked_and_not_at_safepoint();
493 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
494
495 uint dummy_gc_count_before;
496 uint dummy_gclocker_retry_count = 0;
497 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
498 }
499
500 HeapWord*
501 G1CollectedHeap::mem_allocate(size_t word_size,
502 bool* gc_overhead_limit_was_exceeded) {
503 assert_heap_not_locked_and_not_at_safepoint();
504
505 // Loop until the allocation is satisfied, or unsatisfied after GC.
506 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
507 uint gc_count_before;
508
509 HeapWord* result = NULL;
510 if (!is_humongous(word_size)) {
511 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
512 } else {
513 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
514 }
515 if (result != NULL) {
516 return result;
517 }
518
519 // Create the garbage collection operation...
520 VM_G1CollectForAllocation op(gc_count_before, word_size);
521 op.set_allocation_context(AllocationContext::current());
522
523 // ...and get the VM thread to execute it.
524 VMThread::execute(&op);
525
526 if (op.prologue_succeeded() && op.pause_succeeded()) {
527 // If the operation was successful we'll return the result even
528 // if it is NULL. If the allocation attempt failed immediately
529 // after a Full GC, it's unlikely we'll be able to allocate now.
530 HeapWord* result = op.result();
531 if (result != NULL && !is_humongous(word_size)) {
532 // Allocations that take place on VM operations do not do any
533 // card dirtying and we have to do it here. We only have to do
534 // this for non-humongous allocations, though.
535 dirty_young_block(result, word_size);
536 }
537 return result;
538 } else {
539 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
540 return NULL;
541 }
542 assert(op.result() == NULL,
543 "the result should be NULL if the VM op did not succeed");
544 }
545
546 // Give a warning if we seem to be looping forever.
547 if ((QueuedAllocationWarningCount > 0) &&
548 (try_count % QueuedAllocationWarningCount == 0)) {
549 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
550 }
551 }
552
553 ShouldNotReachHere();
554 return NULL;
555 }
556
557 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
558 AllocationContext_t context,
559 uint* gc_count_before_ret,
560 uint* gclocker_retry_count_ret) {
561 // Make sure you read the note in attempt_allocation_humongous().
562
563 assert_heap_not_locked_and_not_at_safepoint();
564 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
565 "be called for humongous allocation requests");
566
567 // We should only get here after the first-level allocation attempt
568 // (attempt_allocation()) failed to allocate.
569
570 // We will loop until a) we manage to successfully perform the
571 // allocation or b) we successfully schedule a collection which
572 // fails to perform the allocation. b) is the only case when we'll
573 // return NULL.
574 HeapWord* result = NULL;
575 for (int try_count = 1; /* we'll return */; try_count += 1) {
576 bool should_try_gc;
577 uint gc_count_before;
578
579 {
580 MutexLockerEx x(Heap_lock);
581 result = _allocator->attempt_allocation_locked(word_size, context);
582 if (result != NULL) {
583 return result;
584 }
585
586 if (GC_locker::is_active_and_needs_gc()) {
587 if (g1_policy()->can_expand_young_list()) {
588 // No need for an ergo verbose message here,
589 // can_expand_young_list() does this when it returns true.
590 result = _allocator->attempt_allocation_force(word_size, context);
591 if (result != NULL) {
592 return result;
593 }
594 }
595 should_try_gc = false;
596 } else {
597 // The GCLocker may not be active but the GCLocker initiated
598 // GC may not yet have been performed (GCLocker::needs_gc()
599 // returns true). In this case we do not try this GC and
600 // wait until the GCLocker initiated GC is performed, and
601 // then retry the allocation.
602 if (GC_locker::needs_gc()) {
603 should_try_gc = false;
604 } else {
605 // Read the GC count while still holding the Heap_lock.
606 gc_count_before = total_collections();
607 should_try_gc = true;
608 }
609 }
610 }
611
612 if (should_try_gc) {
613 bool succeeded;
614 result = do_collection_pause(word_size, gc_count_before, &succeeded,
615 GCCause::_g1_inc_collection_pause);
616 if (result != NULL) {
617 assert(succeeded, "only way to get back a non-NULL result");
618 return result;
619 }
620
621 if (succeeded) {
622 // If we get here we successfully scheduled a collection which
623 // failed to allocate. No point in trying to allocate
624 // further. We'll just return NULL.
625 MutexLockerEx x(Heap_lock);
626 *gc_count_before_ret = total_collections();
627 return NULL;
628 }
629 } else {
630 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
631 MutexLockerEx x(Heap_lock);
632 *gc_count_before_ret = total_collections();
633 return NULL;
634 }
635 // The GCLocker is either active or the GCLocker initiated
636 // GC has not yet been performed. Stall until it is and
637 // then retry the allocation.
638 GC_locker::stall_until_clear();
639 (*gclocker_retry_count_ret) += 1;
640 }
641
642 // We can reach here if we were unsuccessful in scheduling a
643 // collection (because another thread beat us to it) or if we were
644 // stalled due to the GC locker. In either can we should retry the
645 // allocation attempt in case another thread successfully
646 // performed a collection and reclaimed enough space. We do the
647 // first attempt (without holding the Heap_lock) here and the
648 // follow-on attempt will be at the start of the next loop
649 // iteration (after taking the Heap_lock).
650 result = _allocator->attempt_allocation(word_size, context);
651 if (result != NULL) {
652 return result;
653 }
654
655 // Give a warning if we seem to be looping forever.
656 if ((QueuedAllocationWarningCount > 0) &&
657 (try_count % QueuedAllocationWarningCount == 0)) {
658 warning("G1CollectedHeap::attempt_allocation_slow() "
659 "retries %d times", try_count);
660 }
661 }
662
663 ShouldNotReachHere();
664 return NULL;
665 }
666
667 void G1CollectedHeap::begin_archive_alloc_range() {
668 assert_at_safepoint(true /* should_be_vm_thread */);
669 if (_archive_allocator == NULL) {
670 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
671 }
672 }
673
674 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
675 // Allocations in archive regions cannot be of a size that would be considered
676 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
677 // may be different at archive-restore time.
678 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
679 }
680
681 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
682 assert_at_safepoint(true /* should_be_vm_thread */);
683 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
684 if (is_archive_alloc_too_large(word_size)) {
685 return NULL;
686 }
687 return _archive_allocator->archive_mem_allocate(word_size);
688 }
689
690 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
691 size_t end_alignment_in_bytes) {
692 assert_at_safepoint(true /* should_be_vm_thread */);
693 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
694
695 // Call complete_archive to do the real work, filling in the MemRegion
696 // array with the archive regions.
697 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
698 delete _archive_allocator;
699 _archive_allocator = NULL;
700 }
701
702 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
703 assert(ranges != NULL, "MemRegion array NULL");
704 assert(count != 0, "No MemRegions provided");
705 MemRegion reserved = _hrm.reserved();
706 for (size_t i = 0; i < count; i++) {
707 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
708 return false;
709 }
710 }
711 return true;
712 }
713
714 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
715 assert(!is_init_completed(), "Expect to be called at JVM init time");
716 assert(ranges != NULL, "MemRegion array NULL");
717 assert(count != 0, "No MemRegions provided");
718 MutexLockerEx x(Heap_lock);
719
720 MemRegion reserved = _hrm.reserved();
721 HeapWord* prev_last_addr = NULL;
722 HeapRegion* prev_last_region = NULL;
723
724 // Temporarily disable pretouching of heap pages. This interface is used
725 // when mmap'ing archived heap data in, so pre-touching is wasted.
726 FlagSetting fs(AlwaysPreTouch, false);
727
728 // Enable archive object checking in G1MarkSweep. We have to let it know
729 // about each archive range, so that objects in those ranges aren't marked.
730 G1MarkSweep::enable_archive_object_check();
731
732 // For each specified MemRegion range, allocate the corresponding G1
733 // regions and mark them as archive regions. We expect the ranges in
734 // ascending starting address order, without overlap.
735 for (size_t i = 0; i < count; i++) {
736 MemRegion curr_range = ranges[i];
737 HeapWord* start_address = curr_range.start();
738 size_t word_size = curr_range.word_size();
739 HeapWord* last_address = curr_range.last();
740 size_t commits = 0;
741
742 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
743 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
744 p2i(start_address), p2i(last_address));
745 guarantee(start_address > prev_last_addr,
746 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
747 p2i(start_address), p2i(prev_last_addr));
748 prev_last_addr = last_address;
749
750 // Check for ranges that start in the same G1 region in which the previous
751 // range ended, and adjust the start address so we don't try to allocate
752 // the same region again. If the current range is entirely within that
753 // region, skip it, just adjusting the recorded top.
754 HeapRegion* start_region = _hrm.addr_to_region(start_address);
755 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
756 start_address = start_region->end();
757 if (start_address > last_address) {
758 increase_used(word_size * HeapWordSize);
759 start_region->set_top(last_address + 1);
760 continue;
761 }
762 start_region->set_top(start_address);
763 curr_range = MemRegion(start_address, last_address + 1);
764 start_region = _hrm.addr_to_region(start_address);
765 }
766
767 // Perform the actual region allocation, exiting if it fails.
768 // Then note how much new space we have allocated.
769 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
770 return false;
771 }
772 increase_used(word_size * HeapWordSize);
773 if (commits != 0) {
774 ergo_verbose1(ErgoHeapSizing,
775 "attempt heap expansion",
776 ergo_format_reason("allocate archive regions")
777 ergo_format_byte("total size"),
778 HeapRegion::GrainWords * HeapWordSize * commits);
779 }
780
781 // Mark each G1 region touched by the range as archive, add it to the old set,
782 // and set the allocation context and top.
783 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
784 HeapRegion* last_region = _hrm.addr_to_region(last_address);
785 prev_last_region = last_region;
786
787 while (curr_region != NULL) {
788 assert(curr_region->is_empty() && !curr_region->is_pinned(),
789 "Region already in use (index %u)", curr_region->hrm_index());
790 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
791 curr_region->set_allocation_context(AllocationContext::system());
792 curr_region->set_archive();
793 _old_set.add(curr_region);
794 if (curr_region != last_region) {
795 curr_region->set_top(curr_region->end());
796 curr_region = _hrm.next_region_in_heap(curr_region);
797 } else {
798 curr_region->set_top(last_address + 1);
799 curr_region = NULL;
800 }
801 }
802
803 // Notify mark-sweep of the archive range.
804 G1MarkSweep::set_range_archive(curr_range, true);
805 }
806 return true;
807 }
808
809 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
810 assert(!is_init_completed(), "Expect to be called at JVM init time");
811 assert(ranges != NULL, "MemRegion array NULL");
812 assert(count != 0, "No MemRegions provided");
813 MemRegion reserved = _hrm.reserved();
814 HeapWord *prev_last_addr = NULL;
815 HeapRegion* prev_last_region = NULL;
816
817 // For each MemRegion, create filler objects, if needed, in the G1 regions
818 // that contain the address range. The address range actually within the
819 // MemRegion will not be modified. That is assumed to have been initialized
820 // elsewhere, probably via an mmap of archived heap data.
821 MutexLockerEx x(Heap_lock);
822 for (size_t i = 0; i < count; i++) {
823 HeapWord* start_address = ranges[i].start();
824 HeapWord* last_address = ranges[i].last();
825
826 assert(reserved.contains(start_address) && reserved.contains(last_address),
827 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
828 p2i(start_address), p2i(last_address));
829 assert(start_address > prev_last_addr,
830 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
831 p2i(start_address), p2i(prev_last_addr));
832
833 HeapRegion* start_region = _hrm.addr_to_region(start_address);
834 HeapRegion* last_region = _hrm.addr_to_region(last_address);
835 HeapWord* bottom_address = start_region->bottom();
836
837 // Check for a range beginning in the same region in which the
838 // previous one ended.
839 if (start_region == prev_last_region) {
840 bottom_address = prev_last_addr + 1;
841 }
842
843 // Verify that the regions were all marked as archive regions by
844 // alloc_archive_regions.
845 HeapRegion* curr_region = start_region;
846 while (curr_region != NULL) {
847 guarantee(curr_region->is_archive(),
848 "Expected archive region at index %u", curr_region->hrm_index());
849 if (curr_region != last_region) {
850 curr_region = _hrm.next_region_in_heap(curr_region);
851 } else {
852 curr_region = NULL;
853 }
854 }
855
856 prev_last_addr = last_address;
857 prev_last_region = last_region;
858
859 // Fill the memory below the allocated range with dummy object(s),
860 // if the region bottom does not match the range start, or if the previous
861 // range ended within the same G1 region, and there is a gap.
862 if (start_address != bottom_address) {
863 size_t fill_size = pointer_delta(start_address, bottom_address);
864 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
865 increase_used(fill_size * HeapWordSize);
866 }
867 }
868 }
869
870 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
871 uint* gc_count_before_ret,
872 uint* gclocker_retry_count_ret) {
873 assert_heap_not_locked_and_not_at_safepoint();
874 assert(!is_humongous(word_size), "attempt_allocation() should not "
875 "be called for humongous allocation requests");
876
877 AllocationContext_t context = AllocationContext::current();
878 HeapWord* result = _allocator->attempt_allocation(word_size, context);
879
880 if (result == NULL) {
881 result = attempt_allocation_slow(word_size,
882 context,
883 gc_count_before_ret,
884 gclocker_retry_count_ret);
885 }
886 assert_heap_not_locked();
887 if (result != NULL) {
888 dirty_young_block(result, word_size);
889 }
890 return result;
891 }
892
893 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
894 assert(!is_init_completed(), "Expect to be called at JVM init time");
895 assert(ranges != NULL, "MemRegion array NULL");
896 assert(count != 0, "No MemRegions provided");
897 MemRegion reserved = _hrm.reserved();
898 HeapWord* prev_last_addr = NULL;
899 HeapRegion* prev_last_region = NULL;
900 size_t size_used = 0;
901 size_t uncommitted_regions = 0;
902
903 // For each Memregion, free the G1 regions that constitute it, and
904 // notify mark-sweep that the range is no longer to be considered 'archive.'
905 MutexLockerEx x(Heap_lock);
906 for (size_t i = 0; i < count; i++) {
907 HeapWord* start_address = ranges[i].start();
908 HeapWord* last_address = ranges[i].last();
909
910 assert(reserved.contains(start_address) && reserved.contains(last_address),
911 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
912 p2i(start_address), p2i(last_address));
913 assert(start_address > prev_last_addr,
914 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
915 p2i(start_address), p2i(prev_last_addr));
916 size_used += ranges[i].byte_size();
917 prev_last_addr = last_address;
918
919 HeapRegion* start_region = _hrm.addr_to_region(start_address);
920 HeapRegion* last_region = _hrm.addr_to_region(last_address);
921
922 // Check for ranges that start in the same G1 region in which the previous
923 // range ended, and adjust the start address so we don't try to free
924 // the same region again. If the current range is entirely within that
925 // region, skip it.
926 if (start_region == prev_last_region) {
927 start_address = start_region->end();
928 if (start_address > last_address) {
929 continue;
930 }
931 start_region = _hrm.addr_to_region(start_address);
932 }
933 prev_last_region = last_region;
934
935 // After verifying that each region was marked as an archive region by
936 // alloc_archive_regions, set it free and empty and uncommit it.
937 HeapRegion* curr_region = start_region;
938 while (curr_region != NULL) {
939 guarantee(curr_region->is_archive(),
940 "Expected archive region at index %u", curr_region->hrm_index());
941 uint curr_index = curr_region->hrm_index();
942 _old_set.remove(curr_region);
943 curr_region->set_free();
944 curr_region->set_top(curr_region->bottom());
945 if (curr_region != last_region) {
946 curr_region = _hrm.next_region_in_heap(curr_region);
947 } else {
948 curr_region = NULL;
949 }
950 _hrm.shrink_at(curr_index, 1);
951 uncommitted_regions++;
952 }
953
954 // Notify mark-sweep that this is no longer an archive range.
955 G1MarkSweep::set_range_archive(ranges[i], false);
956 }
957
958 if (uncommitted_regions != 0) {
959 ergo_verbose1(ErgoHeapSizing,
960 "attempt heap shrinking",
961 ergo_format_reason("uncommitted archive regions")
962 ergo_format_byte("total size"),
963 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
964 }
965 decrease_used(size_used);
966 }
967
968 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
969 uint* gc_count_before_ret,
970 uint* gclocker_retry_count_ret) {
971 // The structure of this method has a lot of similarities to
972 // attempt_allocation_slow(). The reason these two were not merged
973 // into a single one is that such a method would require several "if
974 // allocation is not humongous do this, otherwise do that"
975 // conditional paths which would obscure its flow. In fact, an early
976 // version of this code did use a unified method which was harder to
977 // follow and, as a result, it had subtle bugs that were hard to
978 // track down. So keeping these two methods separate allows each to
979 // be more readable. It will be good to keep these two in sync as
980 // much as possible.
981
982 assert_heap_not_locked_and_not_at_safepoint();
983 assert(is_humongous(word_size), "attempt_allocation_humongous() "
984 "should only be called for humongous allocations");
985
986 // Humongous objects can exhaust the heap quickly, so we should check if we
987 // need to start a marking cycle at each humongous object allocation. We do
988 // the check before we do the actual allocation. The reason for doing it
989 // before the allocation is that we avoid having to keep track of the newly
990 // allocated memory while we do a GC.
991 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
992 word_size)) {
993 collect(GCCause::_g1_humongous_allocation);
994 }
995
996 // We will loop until a) we manage to successfully perform the
997 // allocation or b) we successfully schedule a collection which
998 // fails to perform the allocation. b) is the only case when we'll
999 // return NULL.
1000 HeapWord* result = NULL;
1001 for (int try_count = 1; /* we'll return */; try_count += 1) {
1002 bool should_try_gc;
1003 uint gc_count_before;
1004
1005 {
1006 MutexLockerEx x(Heap_lock);
1007
1008 // Given that humongous objects are not allocated in young
1009 // regions, we'll first try to do the allocation without doing a
1010 // collection hoping that there's enough space in the heap.
1011 result = humongous_obj_allocate(word_size, AllocationContext::current());
1012 if (result != NULL) {
1013 return result;
1014 }
1015
1016 if (GC_locker::is_active_and_needs_gc()) {
1017 should_try_gc = false;
1018 } else {
1019 // The GCLocker may not be active but the GCLocker initiated
1020 // GC may not yet have been performed (GCLocker::needs_gc()
1021 // returns true). In this case we do not try this GC and
1022 // wait until the GCLocker initiated GC is performed, and
1023 // then retry the allocation.
1024 if (GC_locker::needs_gc()) {
1025 should_try_gc = false;
1026 } else {
1027 // Read the GC count while still holding the Heap_lock.
1028 gc_count_before = total_collections();
1029 should_try_gc = true;
1030 }
1031 }
1032 }
1033
1034 if (should_try_gc) {
1035 // If we failed to allocate the humongous object, we should try to
1036 // do a collection pause (if we're allowed) in case it reclaims
1037 // enough space for the allocation to succeed after the pause.
1038
1039 bool succeeded;
1040 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1041 GCCause::_g1_humongous_allocation);
1042 if (result != NULL) {
1043 assert(succeeded, "only way to get back a non-NULL result");
1044 return result;
1045 }
1046
1047 if (succeeded) {
1048 // If we get here we successfully scheduled a collection which
1049 // failed to allocate. No point in trying to allocate
1050 // further. We'll just return NULL.
1051 MutexLockerEx x(Heap_lock);
1052 *gc_count_before_ret = total_collections();
1053 return NULL;
1054 }
1055 } else {
1056 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1057 MutexLockerEx x(Heap_lock);
1058 *gc_count_before_ret = total_collections();
1059 return NULL;
1060 }
1061 // The GCLocker is either active or the GCLocker initiated
1062 // GC has not yet been performed. Stall until it is and
1063 // then retry the allocation.
1064 GC_locker::stall_until_clear();
1065 (*gclocker_retry_count_ret) += 1;
1066 }
1067
1068 // We can reach here if we were unsuccessful in scheduling a
1069 // collection (because another thread beat us to it) or if we were
1070 // stalled due to the GC locker. In either can we should retry the
1071 // allocation attempt in case another thread successfully
1072 // performed a collection and reclaimed enough space. Give a
1073 // warning if we seem to be looping forever.
1074
1075 if ((QueuedAllocationWarningCount > 0) &&
1076 (try_count % QueuedAllocationWarningCount == 0)) {
1077 warning("G1CollectedHeap::attempt_allocation_humongous() "
1078 "retries %d times", try_count);
1079 }
1080 }
1081
1082 ShouldNotReachHere();
1083 return NULL;
1084 }
1085
1086 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1087 AllocationContext_t context,
1088 bool expect_null_mutator_alloc_region) {
1089 assert_at_safepoint(true /* should_be_vm_thread */);
1090 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1091 "the current alloc region was unexpectedly found to be non-NULL");
1092
1093 if (!is_humongous(word_size)) {
1094 return _allocator->attempt_allocation_locked(word_size, context);
1095 } else {
1096 HeapWord* result = humongous_obj_allocate(word_size, context);
1097 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1098 collector_state()->set_initiate_conc_mark_if_possible(true);
1099 }
1100 return result;
1101 }
1102
1103 ShouldNotReachHere();
1104 }
1105
1106 class PostMCRemSetClearClosure: public HeapRegionClosure {
1107 G1CollectedHeap* _g1h;
1108 ModRefBarrierSet* _mr_bs;
1109 public:
1110 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1111 _g1h(g1h), _mr_bs(mr_bs) {}
1112
1113 bool doHeapRegion(HeapRegion* r) {
1114 HeapRegionRemSet* hrrs = r->rem_set();
1115
1116 _g1h->reset_gc_time_stamps(r);
1117
1118 if (r->is_continues_humongous()) {
1119 // We'll assert that the strong code root list and RSet is empty
1120 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1121 assert(hrrs->occupied() == 0, "RSet should be empty");
1122 } else {
1123 hrrs->clear();
1124 }
1125 // You might think here that we could clear just the cards
1126 // corresponding to the used region. But no: if we leave a dirty card
1127 // in a region we might allocate into, then it would prevent that card
1128 // from being enqueued, and cause it to be missed.
1129 // Re: the performance cost: we shouldn't be doing full GC anyway!
1130 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1131
1132 return false;
1133 }
1134 };
1135
1136 void G1CollectedHeap::clear_rsets_post_compaction() {
1137 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1138 heap_region_iterate(&rs_clear);
1139 }
1140
1141 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1142 G1CollectedHeap* _g1h;
1143 UpdateRSOopClosure _cl;
1144 public:
1145 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1146 _cl(g1->g1_rem_set(), worker_i),
1147 _g1h(g1)
1148 { }
1149
1150 bool doHeapRegion(HeapRegion* r) {
1151 if (!r->is_continues_humongous()) {
1152 _cl.set_from(r);
1153 r->oop_iterate(&_cl);
1154 }
1155 return false;
1156 }
1157 };
1158
1159 class ParRebuildRSTask: public AbstractGangTask {
1160 G1CollectedHeap* _g1;
1161 HeapRegionClaimer _hrclaimer;
1162
1163 public:
1164 ParRebuildRSTask(G1CollectedHeap* g1) :
1165 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1166
1167 void work(uint worker_id) {
1168 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1169 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1170 }
1171 };
1172
1173 class PostCompactionPrinterClosure: public HeapRegionClosure {
1174 private:
1175 G1HRPrinter* _hr_printer;
1176 public:
1177 bool doHeapRegion(HeapRegion* hr) {
1178 assert(!hr->is_young(), "not expecting to find young regions");
1179 if (hr->is_free()) {
1180 // We only generate output for non-empty regions.
1181 } else if (hr->is_starts_humongous()) {
1182 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1183 } else if (hr->is_continues_humongous()) {
1184 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1185 } else if (hr->is_archive()) {
1186 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1187 } else if (hr->is_old()) {
1188 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1189 } else {
1190 ShouldNotReachHere();
1191 }
1192 return false;
1193 }
1194
1195 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1196 : _hr_printer(hr_printer) { }
1197 };
1198
1199 void G1CollectedHeap::print_hrm_post_compaction() {
1200 PostCompactionPrinterClosure cl(hr_printer());
1201 heap_region_iterate(&cl);
1202 }
1203
1204 bool G1CollectedHeap::do_collection(bool explicit_gc,
1205 bool clear_all_soft_refs,
1206 size_t word_size) {
1207 assert_at_safepoint(true /* should_be_vm_thread */);
1208
1209 if (GC_locker::check_active_before_gc()) {
1210 return false;
1211 }
1212
1213 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1214 gc_timer->register_gc_start();
1215
1216 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1217 GCIdMark gc_id_mark;
1218 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1219
1220 SvcGCMarker sgcm(SvcGCMarker::FULL);
1221 ResourceMark rm;
1222
1223 G1Log::update_level();
1224 print_heap_before_gc();
1225 trace_heap_before_gc(gc_tracer);
1226
1227 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1228
1229 verify_region_sets_optional();
1230
1231 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1232 collector_policy()->should_clear_all_soft_refs();
1233
1234 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1235
1236 {
1237 IsGCActiveMark x;
1238
1239 // Timing
1240 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1241 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1242
1243 {
1244 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1245 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1246 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1247
1248 g1_policy()->record_full_collection_start();
1249
1250 // Note: When we have a more flexible GC logging framework that
1251 // allows us to add optional attributes to a GC log record we
1252 // could consider timing and reporting how long we wait in the
1253 // following two methods.
1254 wait_while_free_regions_coming();
1255 // If we start the compaction before the CM threads finish
1256 // scanning the root regions we might trip them over as we'll
1257 // be moving objects / updating references. So let's wait until
1258 // they are done. By telling them to abort, they should complete
1259 // early.
1260 _cm->root_regions()->abort();
1261 _cm->root_regions()->wait_until_scan_finished();
1262 append_secondary_free_list_if_not_empty_with_lock();
1263
1264 gc_prologue(true);
1265 increment_total_collections(true /* full gc */);
1266 increment_old_marking_cycles_started();
1267
1268 assert(used() == recalculate_used(), "Should be equal");
1269
1270 verify_before_gc();
1271
1272 check_bitmaps("Full GC Start");
1273 pre_full_gc_dump(gc_timer);
1274
1275 #if defined(COMPILER2) || INCLUDE_JVMCI
1276 DerivedPointerTable::clear();
1277 #endif
1278
1279 // Disable discovery and empty the discovered lists
1280 // for the CM ref processor.
1281 ref_processor_cm()->disable_discovery();
1282 ref_processor_cm()->abandon_partial_discovery();
1283 ref_processor_cm()->verify_no_references_recorded();
1284
1285 // Abandon current iterations of concurrent marking and concurrent
1286 // refinement, if any are in progress. We have to do this before
1287 // wait_until_scan_finished() below.
1288 concurrent_mark()->abort();
1289
1290 // Make sure we'll choose a new allocation region afterwards.
1291 _allocator->release_mutator_alloc_region();
1292 _allocator->abandon_gc_alloc_regions();
1293 g1_rem_set()->cleanupHRRS();
1294
1295 // We should call this after we retire any currently active alloc
1296 // regions so that all the ALLOC / RETIRE events are generated
1297 // before the start GC event.
1298 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1299
1300 // We may have added regions to the current incremental collection
1301 // set between the last GC or pause and now. We need to clear the
1302 // incremental collection set and then start rebuilding it afresh
1303 // after this full GC.
1304 abandon_collection_set(g1_policy()->inc_cset_head());
1305 g1_policy()->clear_incremental_cset();
1306 g1_policy()->stop_incremental_cset_building();
1307
1308 tear_down_region_sets(false /* free_list_only */);
1309 collector_state()->set_gcs_are_young(true);
1310
1311 // See the comments in g1CollectedHeap.hpp and
1312 // G1CollectedHeap::ref_processing_init() about
1313 // how reference processing currently works in G1.
1314
1315 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1316 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1317
1318 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1319 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1320
1321 ref_processor_stw()->enable_discovery();
1322 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1323
1324 // Do collection work
1325 {
1326 HandleMark hm; // Discard invalid handles created during gc
1327 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1328 }
1329
1330 assert(num_free_regions() == 0, "we should not have added any free regions");
1331 rebuild_region_sets(false /* free_list_only */);
1332
1333 // Enqueue any discovered reference objects that have
1334 // not been removed from the discovered lists.
1335 ref_processor_stw()->enqueue_discovered_references();
1336
1337 #if defined(COMPILER2) || INCLUDE_JVMCI
1338 DerivedPointerTable::update_pointers();
1339 #endif
1340
1341 MemoryService::track_memory_usage();
1342
1343 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1344 ref_processor_stw()->verify_no_references_recorded();
1345
1346 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1347 ClassLoaderDataGraph::purge();
1348 MetaspaceAux::verify_metrics();
1349
1350 // Note: since we've just done a full GC, concurrent
1351 // marking is no longer active. Therefore we need not
1352 // re-enable reference discovery for the CM ref processor.
1353 // That will be done at the start of the next marking cycle.
1354 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1355 ref_processor_cm()->verify_no_references_recorded();
1356
1357 reset_gc_time_stamp();
1358 // Since everything potentially moved, we will clear all remembered
1359 // sets, and clear all cards. Later we will rebuild remembered
1360 // sets. We will also reset the GC time stamps of the regions.
1361 clear_rsets_post_compaction();
1362 check_gc_time_stamps();
1363
1364 // Resize the heap if necessary.
1365 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1366
1367 if (_hr_printer.is_active()) {
1368 // We should do this after we potentially resize the heap so
1369 // that all the COMMIT / UNCOMMIT events are generated before
1370 // the end GC event.
1371
1372 print_hrm_post_compaction();
1373 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1374 }
1375
1376 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1377 if (hot_card_cache->use_cache()) {
1378 hot_card_cache->reset_card_counts();
1379 hot_card_cache->reset_hot_cache();
1380 }
1381
1382 // Rebuild remembered sets of all regions.
1383 uint n_workers =
1384 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1385 workers()->active_workers(),
1386 Threads::number_of_non_daemon_threads());
1387 workers()->set_active_workers(n_workers);
1388
1389 ParRebuildRSTask rebuild_rs_task(this);
1390 workers()->run_task(&rebuild_rs_task);
1391
1392 // Rebuild the strong code root lists for each region
1393 rebuild_strong_code_roots();
1394
1395 if (true) { // FIXME
1396 MetaspaceGC::compute_new_size();
1397 }
1398
1399 #ifdef TRACESPINNING
1400 ParallelTaskTerminator::print_termination_counts();
1401 #endif
1402
1403 // Discard all rset updates
1404 JavaThread::dirty_card_queue_set().abandon_logs();
1405 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1406
1407 _young_list->reset_sampled_info();
1408 // At this point there should be no regions in the
1409 // entire heap tagged as young.
1410 assert(check_young_list_empty(true /* check_heap */),
1411 "young list should be empty at this point");
1412
1413 // Update the number of full collections that have been completed.
1414 increment_old_marking_cycles_completed(false /* concurrent */);
1415
1416 _hrm.verify_optional();
1417 verify_region_sets_optional();
1418
1419 verify_after_gc();
1420
1421 // Clear the previous marking bitmap, if needed for bitmap verification.
1422 // Note we cannot do this when we clear the next marking bitmap in
1423 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1424 // objects marked during a full GC against the previous bitmap.
1425 // But we need to clear it before calling check_bitmaps below since
1426 // the full GC has compacted objects and updated TAMS but not updated
1427 // the prev bitmap.
1428 if (G1VerifyBitmaps) {
1429 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1430 }
1431 check_bitmaps("Full GC End");
1432
1433 // Start a new incremental collection set for the next pause
1434 assert(g1_policy()->collection_set() == NULL, "must be");
1435 g1_policy()->start_incremental_cset_building();
1436
1437 clear_cset_fast_test();
1438
1439 _allocator->init_mutator_alloc_region();
1440
1441 g1_policy()->record_full_collection_end();
1442
1443 if (G1Log::fine()) {
1444 g1_policy()->print_heap_transition();
1445 }
1446
1447 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1448 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1449 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1450 // before any GC notifications are raised.
1451 g1mm()->update_sizes();
1452
1453 gc_epilogue(true);
1454 }
1455
1456 if (G1Log::finer()) {
1457 g1_policy()->print_detailed_heap_transition(true /* full */);
1458 }
1459
1460 print_heap_after_gc();
1461 trace_heap_after_gc(gc_tracer);
1462
1463 post_full_gc_dump(gc_timer);
1464
1465 gc_timer->register_gc_end();
1466 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1467 }
1468
1469 return true;
1470 }
1471
1472 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1473 // do_collection() will return whether it succeeded in performing
1474 // the GC. Currently, there is no facility on the
1475 // do_full_collection() API to notify the caller than the collection
1476 // did not succeed (e.g., because it was locked out by the GC
1477 // locker). So, right now, we'll ignore the return value.
1478 bool dummy = do_collection(true, /* explicit_gc */
1479 clear_all_soft_refs,
1480 0 /* word_size */);
1481 }
1482
1483 // This code is mostly copied from TenuredGeneration.
1484 void
1485 G1CollectedHeap::
1486 resize_if_necessary_after_full_collection(size_t word_size) {
1487 // Include the current allocation, if any, and bytes that will be
1488 // pre-allocated to support collections, as "used".
1489 const size_t used_after_gc = used();
1490 const size_t capacity_after_gc = capacity();
1491 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1492
1493 // This is enforced in arguments.cpp.
1494 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1495 "otherwise the code below doesn't make sense");
1496
1497 // We don't have floating point command-line arguments
1498 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1499 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1500 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1501 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1502
1503 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1504 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1505
1506 // We have to be careful here as these two calculations can overflow
1507 // 32-bit size_t's.
1508 double used_after_gc_d = (double) used_after_gc;
1509 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1510 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1511
1512 // Let's make sure that they are both under the max heap size, which
1513 // by default will make them fit into a size_t.
1514 double desired_capacity_upper_bound = (double) max_heap_size;
1515 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1516 desired_capacity_upper_bound);
1517 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1518 desired_capacity_upper_bound);
1519
1520 // We can now safely turn them into size_t's.
1521 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1522 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1523
1524 // This assert only makes sense here, before we adjust them
1525 // with respect to the min and max heap size.
1526 assert(minimum_desired_capacity <= maximum_desired_capacity,
1527 "minimum_desired_capacity = " SIZE_FORMAT ", "
1528 "maximum_desired_capacity = " SIZE_FORMAT,
1529 minimum_desired_capacity, maximum_desired_capacity);
1530
1531 // Should not be greater than the heap max size. No need to adjust
1532 // it with respect to the heap min size as it's a lower bound (i.e.,
1533 // we'll try to make the capacity larger than it, not smaller).
1534 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1535 // Should not be less than the heap min size. No need to adjust it
1536 // with respect to the heap max size as it's an upper bound (i.e.,
1537 // we'll try to make the capacity smaller than it, not greater).
1538 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1539
1540 if (capacity_after_gc < minimum_desired_capacity) {
1541 // Don't expand unless it's significant
1542 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1543 ergo_verbose4(ErgoHeapSizing,
1544 "attempt heap expansion",
1545 ergo_format_reason("capacity lower than "
1546 "min desired capacity after Full GC")
1547 ergo_format_byte("capacity")
1548 ergo_format_byte("occupancy")
1549 ergo_format_byte_perc("min desired capacity"),
1550 capacity_after_gc, used_after_gc,
1551 minimum_desired_capacity, (double) MinHeapFreeRatio);
1552 expand(expand_bytes);
1553
1554 // No expansion, now see if we want to shrink
1555 } else if (capacity_after_gc > maximum_desired_capacity) {
1556 // Capacity too large, compute shrinking size
1557 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1558 ergo_verbose4(ErgoHeapSizing,
1559 "attempt heap shrinking",
1560 ergo_format_reason("capacity higher than "
1561 "max desired capacity after Full GC")
1562 ergo_format_byte("capacity")
1563 ergo_format_byte("occupancy")
1564 ergo_format_byte_perc("max desired capacity"),
1565 capacity_after_gc, used_after_gc,
1566 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1567 shrink(shrink_bytes);
1568 }
1569 }
1570
1571 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1572 AllocationContext_t context,
1573 bool do_gc,
1574 bool clear_all_soft_refs,
1575 bool expect_null_mutator_alloc_region,
1576 bool* gc_succeeded) {
1577 *gc_succeeded = true;
1578 // Let's attempt the allocation first.
1579 HeapWord* result =
1580 attempt_allocation_at_safepoint(word_size,
1581 context,
1582 expect_null_mutator_alloc_region);
1583 if (result != NULL) {
1584 assert(*gc_succeeded, "sanity");
1585 return result;
1586 }
1587
1588 // In a G1 heap, we're supposed to keep allocation from failing by
1589 // incremental pauses. Therefore, at least for now, we'll favor
1590 // expansion over collection. (This might change in the future if we can
1591 // do something smarter than full collection to satisfy a failed alloc.)
1592 result = expand_and_allocate(word_size, context);
1593 if (result != NULL) {
1594 assert(*gc_succeeded, "sanity");
1595 return result;
1596 }
1597
1598 if (do_gc) {
1599 // Expansion didn't work, we'll try to do a Full GC.
1600 *gc_succeeded = do_collection(false, /* explicit_gc */
1601 clear_all_soft_refs,
1602 word_size);
1603 }
1604
1605 return NULL;
1606 }
1607
1608 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1609 AllocationContext_t context,
1610 bool* succeeded) {
1611 assert_at_safepoint(true /* should_be_vm_thread */);
1612
1613 // Attempts to allocate followed by Full GC.
1614 HeapWord* result =
1615 satisfy_failed_allocation_helper(word_size,
1616 context,
1617 true, /* do_gc */
1618 false, /* clear_all_soft_refs */
1619 false, /* expect_null_mutator_alloc_region */
1620 succeeded);
1621
1622 if (result != NULL || !*succeeded) {
1623 return result;
1624 }
1625
1626 // Attempts to allocate followed by Full GC that will collect all soft references.
1627 result = satisfy_failed_allocation_helper(word_size,
1628 context,
1629 true, /* do_gc */
1630 true, /* clear_all_soft_refs */
1631 true, /* expect_null_mutator_alloc_region */
1632 succeeded);
1633
1634 if (result != NULL || !*succeeded) {
1635 return result;
1636 }
1637
1638 // Attempts to allocate, no GC
1639 result = satisfy_failed_allocation_helper(word_size,
1640 context,
1641 false, /* do_gc */
1642 false, /* clear_all_soft_refs */
1643 true, /* expect_null_mutator_alloc_region */
1644 succeeded);
1645
1646 if (result != NULL) {
1647 assert(*succeeded, "sanity");
1648 return result;
1649 }
1650
1651 assert(!collector_policy()->should_clear_all_soft_refs(),
1652 "Flag should have been handled and cleared prior to this point");
1653
1654 // What else? We might try synchronous finalization later. If the total
1655 // space available is large enough for the allocation, then a more
1656 // complete compaction phase than we've tried so far might be
1657 // appropriate.
1658 assert(*succeeded, "sanity");
1659 return NULL;
1660 }
1661
1662 // Attempting to expand the heap sufficiently
1663 // to support an allocation of the given "word_size". If
1664 // successful, perform the allocation and return the address of the
1665 // allocated block, or else "NULL".
1666
1667 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1668 assert_at_safepoint(true /* should_be_vm_thread */);
1669
1670 verify_region_sets_optional();
1671
1672 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1673 ergo_verbose1(ErgoHeapSizing,
1674 "attempt heap expansion",
1675 ergo_format_reason("allocation request failed")
1676 ergo_format_byte("allocation request"),
1677 word_size * HeapWordSize);
1678 if (expand(expand_bytes)) {
1679 _hrm.verify_optional();
1680 verify_region_sets_optional();
1681 return attempt_allocation_at_safepoint(word_size,
1682 context,
1683 false /* expect_null_mutator_alloc_region */);
1684 }
1685 return NULL;
1686 }
1687
1688 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1689 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1690 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1691 HeapRegion::GrainBytes);
1692 ergo_verbose2(ErgoHeapSizing,
1693 "expand the heap",
1694 ergo_format_byte("requested expansion amount")
1695 ergo_format_byte("attempted expansion amount"),
1696 expand_bytes, aligned_expand_bytes);
1697
1698 if (is_maximal_no_gc()) {
1699 ergo_verbose0(ErgoHeapSizing,
1700 "did not expand the heap",
1701 ergo_format_reason("heap already fully expanded"));
1702 return false;
1703 }
1704
1705 double expand_heap_start_time_sec = os::elapsedTime();
1706 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1707 assert(regions_to_expand > 0, "Must expand by at least one region");
1708
1709 uint expanded_by = _hrm.expand_by(regions_to_expand);
1710 if (expand_time_ms != NULL) {
1711 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1712 }
1713
1714 if (expanded_by > 0) {
1715 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1716 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1717 g1_policy()->record_new_heap_size(num_regions());
1718 } else {
1719 ergo_verbose0(ErgoHeapSizing,
1720 "did not expand the heap",
1721 ergo_format_reason("heap expansion operation failed"));
1722 // The expansion of the virtual storage space was unsuccessful.
1723 // Let's see if it was because we ran out of swap.
1724 if (G1ExitOnExpansionFailure &&
1725 _hrm.available() >= regions_to_expand) {
1726 // We had head room...
1727 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1728 }
1729 }
1730 return regions_to_expand > 0;
1731 }
1732
1733 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1734 size_t aligned_shrink_bytes =
1735 ReservedSpace::page_align_size_down(shrink_bytes);
1736 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1737 HeapRegion::GrainBytes);
1738 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1739
1740 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1741 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1742
1743 ergo_verbose3(ErgoHeapSizing,
1744 "shrink the heap",
1745 ergo_format_byte("requested shrinking amount")
1746 ergo_format_byte("aligned shrinking amount")
1747 ergo_format_byte("attempted shrinking amount"),
1748 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1749 if (num_regions_removed > 0) {
1750 g1_policy()->record_new_heap_size(num_regions());
1751 } else {
1752 ergo_verbose0(ErgoHeapSizing,
1753 "did not shrink the heap",
1754 ergo_format_reason("heap shrinking operation failed"));
1755 }
1756 }
1757
1758 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1759 verify_region_sets_optional();
1760
1761 // We should only reach here at the end of a Full GC which means we
1762 // should not not be holding to any GC alloc regions. The method
1763 // below will make sure of that and do any remaining clean up.
1764 _allocator->abandon_gc_alloc_regions();
1765
1766 // Instead of tearing down / rebuilding the free lists here, we
1767 // could instead use the remove_all_pending() method on free_list to
1768 // remove only the ones that we need to remove.
1769 tear_down_region_sets(true /* free_list_only */);
1770 shrink_helper(shrink_bytes);
1771 rebuild_region_sets(true /* free_list_only */);
1772
1773 _hrm.verify_optional();
1774 verify_region_sets_optional();
1775 }
1776
1777 // Public methods.
1778
1779 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1780 CollectedHeap(),
1781 _g1_policy(policy_),
1782 _dirty_card_queue_set(false),
1783 _is_alive_closure_cm(this),
1784 _is_alive_closure_stw(this),
1785 _ref_processor_cm(NULL),
1786 _ref_processor_stw(NULL),
1787 _bot_shared(NULL),
1788 _cg1r(NULL),
1789 _g1mm(NULL),
1790 _refine_cte_cl(NULL),
1791 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1792 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1793 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1794 _humongous_reclaim_candidates(),
1795 _has_humongous_reclaim_candidates(false),
1796 _archive_allocator(NULL),
1797 _free_regions_coming(false),
1798 _young_list(new YoungList(this)),
1799 _gc_time_stamp(0),
1800 _summary_bytes_used(0),
1801 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1802 _old_evac_stats(OldPLABSize, PLABWeight),
1803 _expand_heap_after_alloc_failure(true),
1804 _old_marking_cycles_started(0),
1805 _old_marking_cycles_completed(0),
1806 _heap_summary_sent(false),
1807 _in_cset_fast_test(),
1808 _dirty_cards_region_list(NULL),
1809 _worker_cset_start_region(NULL),
1810 _worker_cset_start_region_time_stamp(NULL),
1811 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1812 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1813 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1814 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1815
1816 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1817 /* are_GC_task_threads */true,
1818 /* are_ConcurrentGC_threads */false);
1819 _workers->initialize_workers();
1820
1821 _allocator = G1Allocator::create_allocator(this);
1822 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1823
1824 // Override the default _filler_array_max_size so that no humongous filler
1825 // objects are created.
1826 _filler_array_max_size = _humongous_object_threshold_in_words;
1827
1828 uint n_queues = ParallelGCThreads;
1829 _task_queues = new RefToScanQueueSet(n_queues);
1830
1831 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1832 assert(n_rem_sets > 0, "Invariant.");
1833
1834 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1835 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1836 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1837
1838 for (uint i = 0; i < n_queues; i++) {
1839 RefToScanQueue* q = new RefToScanQueue();
1840 q->initialize();
1841 _task_queues->register_queue(i, q);
1842 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1843 }
1844 clear_cset_start_regions();
1845
1846 // Initialize the G1EvacuationFailureALot counters and flags.
1847 NOT_PRODUCT(reset_evacuation_should_fail();)
1848
1849 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1850 }
1851
1852 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1853 size_t size,
1854 size_t translation_factor) {
1855 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1856 // Allocate a new reserved space, preferring to use large pages.
1857 ReservedSpace rs(size, preferred_page_size);
1858 G1RegionToSpaceMapper* result =
1859 G1RegionToSpaceMapper::create_mapper(rs,
1860 size,
1861 rs.alignment(),
1862 HeapRegion::GrainBytes,
1863 translation_factor,
1864 mtGC);
1865 if (TracePageSizes) {
1866 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1867 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1868 }
1869 return result;
1870 }
1871
1872 jint G1CollectedHeap::initialize() {
1873 CollectedHeap::pre_initialize();
1874 os::enable_vtime();
1875
1876 G1Log::init();
1877
1878 // Necessary to satisfy locking discipline assertions.
1879
1880 MutexLocker x(Heap_lock);
1881
1882 // We have to initialize the printer before committing the heap, as
1883 // it will be used then.
1884 _hr_printer.set_active(G1PrintHeapRegions);
1885
1886 // While there are no constraints in the GC code that HeapWordSize
1887 // be any particular value, there are multiple other areas in the
1888 // system which believe this to be true (e.g. oop->object_size in some
1889 // cases incorrectly returns the size in wordSize units rather than
1890 // HeapWordSize).
1891 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1892
1893 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1894 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1895 size_t heap_alignment = collector_policy()->heap_alignment();
1896
1897 // Ensure that the sizes are properly aligned.
1898 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1899 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1900 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1901
1902 _refine_cte_cl = new RefineCardTableEntryClosure();
1903
1904 jint ecode = JNI_OK;
1905 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1906 if (_cg1r == NULL) {
1907 return ecode;
1908 }
1909
1910 // Reserve the maximum.
1911
1912 // When compressed oops are enabled, the preferred heap base
1913 // is calculated by subtracting the requested size from the
1914 // 32Gb boundary and using the result as the base address for
1915 // heap reservation. If the requested size is not aligned to
1916 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1917 // into the ReservedHeapSpace constructor) then the actual
1918 // base of the reserved heap may end up differing from the
1919 // address that was requested (i.e. the preferred heap base).
1920 // If this happens then we could end up using a non-optimal
1921 // compressed oops mode.
1922
1923 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1924 heap_alignment);
1925
1926 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1927
1928 // Create the barrier set for the entire reserved region.
1929 G1SATBCardTableLoggingModRefBS* bs
1930 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1931 bs->initialize();
1932 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1933 set_barrier_set(bs);
1934
1935 // Also create a G1 rem set.
1936 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1937
1938 // Carve out the G1 part of the heap.
1939
1940 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1941 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1942 G1RegionToSpaceMapper* heap_storage =
1943 G1RegionToSpaceMapper::create_mapper(g1_rs,
1944 g1_rs.size(),
1945 page_size,
1946 HeapRegion::GrainBytes,
1947 1,
1948 mtJavaHeap);
1949 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1950 max_byte_size, page_size,
1951 heap_rs.base(),
1952 heap_rs.size());
1953 heap_storage->set_mapping_changed_listener(&_listener);
1954
1955 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1956 G1RegionToSpaceMapper* bot_storage =
1957 create_aux_memory_mapper("Block offset table",
1958 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1959 G1BlockOffsetSharedArray::heap_map_factor());
1960
1961 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1962 G1RegionToSpaceMapper* cardtable_storage =
1963 create_aux_memory_mapper("Card table",
1964 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1965 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1966
1967 G1RegionToSpaceMapper* card_counts_storage =
1968 create_aux_memory_mapper("Card counts table",
1969 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1970 G1CardCounts::heap_map_factor());
1971
1972 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1973 G1RegionToSpaceMapper* prev_bitmap_storage =
1974 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1975 G1RegionToSpaceMapper* next_bitmap_storage =
1976 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1977
1978 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1979 g1_barrier_set()->initialize(cardtable_storage);
1980 // Do later initialization work for concurrent refinement.
1981 _cg1r->init(card_counts_storage);
1982
1983 // 6843694 - ensure that the maximum region index can fit
1984 // in the remembered set structures.
1985 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1986 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1987
1988 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1989 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1990 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1991 "too many cards per region");
1992
1993 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1994
1995 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1996
1997 {
1998 HeapWord* start = _hrm.reserved().start();
1999 HeapWord* end = _hrm.reserved().end();
2000 size_t granularity = HeapRegion::GrainBytes;
2001
2002 _in_cset_fast_test.initialize(start, end, granularity);
2003 _humongous_reclaim_candidates.initialize(start, end, granularity);
2004 }
2005
2006 // Create the ConcurrentMark data structure and thread.
2007 // (Must do this late, so that "max_regions" is defined.)
2008 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2009 if (_cm == NULL || !_cm->completed_initialization()) {
2010 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2011 return JNI_ENOMEM;
2012 }
2013 _cmThread = _cm->cmThread();
2014
2015 // Initialize the from_card cache structure of HeapRegionRemSet.
2016 HeapRegionRemSet::init_heap(max_regions());
2017
2018 // Now expand into the initial heap size.
2019 if (!expand(init_byte_size)) {
2020 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2021 return JNI_ENOMEM;
2022 }
2023
2024 // Perform any initialization actions delegated to the policy.
2025 g1_policy()->init();
2026
2027 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2028 SATB_Q_FL_lock,
2029 G1SATBProcessCompletedThreshold,
2030 Shared_SATB_Q_lock);
2031
2032 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2033 DirtyCardQ_CBL_mon,
2034 DirtyCardQ_FL_lock,
2035 concurrent_g1_refine()->yellow_zone(),
2036 concurrent_g1_refine()->red_zone(),
2037 Shared_DirtyCardQ_lock);
2038
2039 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2040 DirtyCardQ_CBL_mon,
2041 DirtyCardQ_FL_lock,
2042 -1, // never trigger processing
2043 -1, // no limit on length
2044 Shared_DirtyCardQ_lock,
2045 &JavaThread::dirty_card_queue_set());
2046
2047 // Here we allocate the dummy HeapRegion that is required by the
2048 // G1AllocRegion class.
2049 HeapRegion* dummy_region = _hrm.get_dummy_region();
2050
2051 // We'll re-use the same region whether the alloc region will
2052 // require BOT updates or not and, if it doesn't, then a non-young
2053 // region will complain that it cannot support allocations without
2054 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2055 dummy_region->set_eden();
2056 // Make sure it's full.
2057 dummy_region->set_top(dummy_region->end());
2058 G1AllocRegion::setup(this, dummy_region);
2059
2060 _allocator->init_mutator_alloc_region();
2061
2062 // Do create of the monitoring and management support so that
2063 // values in the heap have been properly initialized.
2064 _g1mm = new G1MonitoringSupport(this);
2065
2066 G1StringDedup::initialize();
2067
2068 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2069 for (uint i = 0; i < ParallelGCThreads; i++) {
2070 new (&_preserved_objs[i]) OopAndMarkOopStack();
2071 }
2072
2073 return JNI_OK;
2074 }
2075
2076 void G1CollectedHeap::stop() {
2077 // Stop all concurrent threads. We do this to make sure these threads
2078 // do not continue to execute and access resources (e.g. gclog_or_tty)
2079 // that are destroyed during shutdown.
2080 _cg1r->stop();
2081 _cmThread->stop();
2082 if (G1StringDedup::is_enabled()) {
2083 G1StringDedup::stop();
2084 }
2085 }
2086
2087 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2088 return HeapRegion::max_region_size();
2089 }
2090
2091 void G1CollectedHeap::post_initialize() {
2092 CollectedHeap::post_initialize();
2093 ref_processing_init();
2094 }
2095
2096 void G1CollectedHeap::ref_processing_init() {
2097 // Reference processing in G1 currently works as follows:
2098 //
2099 // * There are two reference processor instances. One is
2100 // used to record and process discovered references
2101 // during concurrent marking; the other is used to
2102 // record and process references during STW pauses
2103 // (both full and incremental).
2104 // * Both ref processors need to 'span' the entire heap as
2105 // the regions in the collection set may be dotted around.
2106 //
2107 // * For the concurrent marking ref processor:
2108 // * Reference discovery is enabled at initial marking.
2109 // * Reference discovery is disabled and the discovered
2110 // references processed etc during remarking.
2111 // * Reference discovery is MT (see below).
2112 // * Reference discovery requires a barrier (see below).
2113 // * Reference processing may or may not be MT
2114 // (depending on the value of ParallelRefProcEnabled
2115 // and ParallelGCThreads).
2116 // * A full GC disables reference discovery by the CM
2117 // ref processor and abandons any entries on it's
2118 // discovered lists.
2119 //
2120 // * For the STW processor:
2121 // * Non MT discovery is enabled at the start of a full GC.
2122 // * Processing and enqueueing during a full GC is non-MT.
2123 // * During a full GC, references are processed after marking.
2124 //
2125 // * Discovery (may or may not be MT) is enabled at the start
2126 // of an incremental evacuation pause.
2127 // * References are processed near the end of a STW evacuation pause.
2128 // * For both types of GC:
2129 // * Discovery is atomic - i.e. not concurrent.
2130 // * Reference discovery will not need a barrier.
2131
2132 MemRegion mr = reserved_region();
2133
2134 // Concurrent Mark ref processor
2135 _ref_processor_cm =
2136 new ReferenceProcessor(mr, // span
2137 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2138 // mt processing
2139 ParallelGCThreads,
2140 // degree of mt processing
2141 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2142 // mt discovery
2143 MAX2(ParallelGCThreads, ConcGCThreads),
2144 // degree of mt discovery
2145 false,
2146 // Reference discovery is not atomic
2147 &_is_alive_closure_cm);
2148 // is alive closure
2149 // (for efficiency/performance)
2150
2151 // STW ref processor
2152 _ref_processor_stw =
2153 new ReferenceProcessor(mr, // span
2154 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2155 // mt processing
2156 ParallelGCThreads,
2157 // degree of mt processing
2158 (ParallelGCThreads > 1),
2159 // mt discovery
2160 ParallelGCThreads,
2161 // degree of mt discovery
2162 true,
2163 // Reference discovery is atomic
2164 &_is_alive_closure_stw);
2165 // is alive closure
2166 // (for efficiency/performance)
2167 }
2168
2169 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2170 return g1_policy();
2171 }
2172
2173 size_t G1CollectedHeap::capacity() const {
2174 return _hrm.length() * HeapRegion::GrainBytes;
2175 }
2176
2177 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2178 hr->reset_gc_time_stamp();
2179 }
2180
2181 #ifndef PRODUCT
2182
2183 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2184 private:
2185 unsigned _gc_time_stamp;
2186 bool _failures;
2187
2188 public:
2189 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2190 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2191
2192 virtual bool doHeapRegion(HeapRegion* hr) {
2193 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2194 if (_gc_time_stamp != region_gc_time_stamp) {
2195 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2196 "expected %d", HR_FORMAT_PARAMS(hr),
2197 region_gc_time_stamp, _gc_time_stamp);
2198 _failures = true;
2199 }
2200 return false;
2201 }
2202
2203 bool failures() { return _failures; }
2204 };
2205
2206 void G1CollectedHeap::check_gc_time_stamps() {
2207 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2208 heap_region_iterate(&cl);
2209 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2210 }
2211 #endif // PRODUCT
2212
2213 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2214 _cg1r->hot_card_cache()->drain(cl, worker_i);
2215 }
2216
2217 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2218 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2219 size_t n_completed_buffers = 0;
2220 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2221 n_completed_buffers++;
2222 }
2223 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2224 dcqs.clear_n_completed_buffers();
2225 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2226 }
2227
2228 // Computes the sum of the storage used by the various regions.
2229 size_t G1CollectedHeap::used() const {
2230 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2231 if (_archive_allocator != NULL) {
2232 result += _archive_allocator->used();
2233 }
2234 return result;
2235 }
2236
2237 size_t G1CollectedHeap::used_unlocked() const {
2238 return _summary_bytes_used;
2239 }
2240
2241 class SumUsedClosure: public HeapRegionClosure {
2242 size_t _used;
2243 public:
2244 SumUsedClosure() : _used(0) {}
2245 bool doHeapRegion(HeapRegion* r) {
2246 _used += r->used();
2247 return false;
2248 }
2249 size_t result() { return _used; }
2250 };
2251
2252 size_t G1CollectedHeap::recalculate_used() const {
2253 double recalculate_used_start = os::elapsedTime();
2254
2255 SumUsedClosure blk;
2256 heap_region_iterate(&blk);
2257
2258 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2259 return blk.result();
2260 }
2261
2262 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2263 switch (cause) {
2264 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2265 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2266 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2267 case GCCause::_g1_humongous_allocation: return true;
2268 case GCCause::_update_allocation_context_stats_inc: return true;
2269 case GCCause::_wb_conc_mark: return true;
2270 default: return false;
2271 }
2272 }
2273
2274 #ifndef PRODUCT
2275 void G1CollectedHeap::allocate_dummy_regions() {
2276 // Let's fill up most of the region
2277 size_t word_size = HeapRegion::GrainWords - 1024;
2278 // And as a result the region we'll allocate will be humongous.
2279 guarantee(is_humongous(word_size), "sanity");
2280
2281 // _filler_array_max_size is set to humongous object threshold
2282 // but temporarily change it to use CollectedHeap::fill_with_object().
2283 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2284
2285 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2286 // Let's use the existing mechanism for the allocation
2287 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2288 AllocationContext::system());
2289 if (dummy_obj != NULL) {
2290 MemRegion mr(dummy_obj, word_size);
2291 CollectedHeap::fill_with_object(mr);
2292 } else {
2293 // If we can't allocate once, we probably cannot allocate
2294 // again. Let's get out of the loop.
2295 break;
2296 }
2297 }
2298 }
2299 #endif // !PRODUCT
2300
2301 void G1CollectedHeap::increment_old_marking_cycles_started() {
2302 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2303 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2304 "Wrong marking cycle count (started: %d, completed: %d)",
2305 _old_marking_cycles_started, _old_marking_cycles_completed);
2306
2307 _old_marking_cycles_started++;
2308 }
2309
2310 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2311 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2312
2313 // We assume that if concurrent == true, then the caller is a
2314 // concurrent thread that was joined the Suspendible Thread
2315 // Set. If there's ever a cheap way to check this, we should add an
2316 // assert here.
2317
2318 // Given that this method is called at the end of a Full GC or of a
2319 // concurrent cycle, and those can be nested (i.e., a Full GC can
2320 // interrupt a concurrent cycle), the number of full collections
2321 // completed should be either one (in the case where there was no
2322 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2323 // behind the number of full collections started.
2324
2325 // This is the case for the inner caller, i.e. a Full GC.
2326 assert(concurrent ||
2327 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2328 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2329 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2330 "is inconsistent with _old_marking_cycles_completed = %u",
2331 _old_marking_cycles_started, _old_marking_cycles_completed);
2332
2333 // This is the case for the outer caller, i.e. the concurrent cycle.
2334 assert(!concurrent ||
2335 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2336 "for outer caller (concurrent cycle): "
2337 "_old_marking_cycles_started = %u "
2338 "is inconsistent with _old_marking_cycles_completed = %u",
2339 _old_marking_cycles_started, _old_marking_cycles_completed);
2340
2341 _old_marking_cycles_completed += 1;
2342
2343 // We need to clear the "in_progress" flag in the CM thread before
2344 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2345 // is set) so that if a waiter requests another System.gc() it doesn't
2346 // incorrectly see that a marking cycle is still in progress.
2347 if (concurrent) {
2348 _cmThread->set_idle();
2349 }
2350
2351 // This notify_all() will ensure that a thread that called
2352 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2353 // and it's waiting for a full GC to finish will be woken up. It is
2354 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2355 FullGCCount_lock->notify_all();
2356 }
2357
2358 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2359 GCIdMarkAndRestore conc_gc_id_mark;
2360 collector_state()->set_concurrent_cycle_started(true);
2361 _gc_timer_cm->register_gc_start(start_time);
2362
2363 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2364 trace_heap_before_gc(_gc_tracer_cm);
2365 _cmThread->set_gc_id(GCId::current());
2366 }
2367
2368 void G1CollectedHeap::register_concurrent_cycle_end() {
2369 if (collector_state()->concurrent_cycle_started()) {
2370 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2371 if (_cm->has_aborted()) {
2372 _gc_tracer_cm->report_concurrent_mode_failure();
2373 }
2374
2375 _gc_timer_cm->register_gc_end();
2376 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2377
2378 // Clear state variables to prepare for the next concurrent cycle.
2379 collector_state()->set_concurrent_cycle_started(false);
2380 _heap_summary_sent = false;
2381 }
2382 }
2383
2384 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2385 if (collector_state()->concurrent_cycle_started()) {
2386 // This function can be called when:
2387 // the cleanup pause is run
2388 // the concurrent cycle is aborted before the cleanup pause.
2389 // the concurrent cycle is aborted after the cleanup pause,
2390 // but before the concurrent cycle end has been registered.
2391 // Make sure that we only send the heap information once.
2392 if (!_heap_summary_sent) {
2393 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2394 trace_heap_after_gc(_gc_tracer_cm);
2395 _heap_summary_sent = true;
2396 }
2397 }
2398 }
2399
2400 void G1CollectedHeap::collect(GCCause::Cause cause) {
2401 assert_heap_not_locked();
2402
2403 uint gc_count_before;
2404 uint old_marking_count_before;
2405 uint full_gc_count_before;
2406 bool retry_gc;
2407
2408 do {
2409 retry_gc = false;
2410
2411 {
2412 MutexLocker ml(Heap_lock);
2413
2414 // Read the GC count while holding the Heap_lock
2415 gc_count_before = total_collections();
2416 full_gc_count_before = total_full_collections();
2417 old_marking_count_before = _old_marking_cycles_started;
2418 }
2419
2420 if (should_do_concurrent_full_gc(cause)) {
2421 // Schedule an initial-mark evacuation pause that will start a
2422 // concurrent cycle. We're setting word_size to 0 which means that
2423 // we are not requesting a post-GC allocation.
2424 VM_G1IncCollectionPause op(gc_count_before,
2425 0, /* word_size */
2426 true, /* should_initiate_conc_mark */
2427 g1_policy()->max_pause_time_ms(),
2428 cause);
2429 op.set_allocation_context(AllocationContext::current());
2430
2431 VMThread::execute(&op);
2432 if (!op.pause_succeeded()) {
2433 if (old_marking_count_before == _old_marking_cycles_started) {
2434 retry_gc = op.should_retry_gc();
2435 } else {
2436 // A Full GC happened while we were trying to schedule the
2437 // initial-mark GC. No point in starting a new cycle given
2438 // that the whole heap was collected anyway.
2439 }
2440
2441 if (retry_gc) {
2442 if (GC_locker::is_active_and_needs_gc()) {
2443 GC_locker::stall_until_clear();
2444 }
2445 }
2446 }
2447 } else {
2448 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2449 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2450
2451 // Schedule a standard evacuation pause. We're setting word_size
2452 // to 0 which means that we are not requesting a post-GC allocation.
2453 VM_G1IncCollectionPause op(gc_count_before,
2454 0, /* word_size */
2455 false, /* should_initiate_conc_mark */
2456 g1_policy()->max_pause_time_ms(),
2457 cause);
2458 VMThread::execute(&op);
2459 } else {
2460 // Schedule a Full GC.
2461 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2462 VMThread::execute(&op);
2463 }
2464 }
2465 } while (retry_gc);
2466 }
2467
2468 bool G1CollectedHeap::is_in(const void* p) const {
2469 if (_hrm.reserved().contains(p)) {
2470 // Given that we know that p is in the reserved space,
2471 // heap_region_containing() should successfully
2472 // return the containing region.
2473 HeapRegion* hr = heap_region_containing(p);
2474 return hr->is_in(p);
2475 } else {
2476 return false;
2477 }
2478 }
2479
2480 #ifdef ASSERT
2481 bool G1CollectedHeap::is_in_exact(const void* p) const {
2482 bool contains = reserved_region().contains(p);
2483 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2484 if (contains && available) {
2485 return true;
2486 } else {
2487 return false;
2488 }
2489 }
2490 #endif
2491
2492 bool G1CollectedHeap::obj_in_cs(oop obj) {
2493 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2494 return r != NULL && r->in_collection_set();
2495 }
2496
2497 // Iteration functions.
2498
2499 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2500
2501 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2502 ExtendedOopClosure* _cl;
2503 public:
2504 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2505 bool doHeapRegion(HeapRegion* r) {
2506 if (!r->is_continues_humongous()) {
2507 r->oop_iterate(_cl);
2508 }
2509 return false;
2510 }
2511 };
2512
2513 // Iterates an ObjectClosure over all objects within a HeapRegion.
2514
2515 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2516 ObjectClosure* _cl;
2517 public:
2518 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2519 bool doHeapRegion(HeapRegion* r) {
2520 if (!r->is_continues_humongous()) {
2521 r->object_iterate(_cl);
2522 }
2523 return false;
2524 }
2525 };
2526
2527 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2528 IterateObjectClosureRegionClosure blk(cl);
2529 heap_region_iterate(&blk);
2530 }
2531
2532 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2533 _hrm.iterate(cl);
2534 }
2535
2536 void
2537 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2538 uint worker_id,
2539 HeapRegionClaimer *hrclaimer,
2540 bool concurrent) const {
2541 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2542 }
2543
2544 // Clear the cached CSet starting regions and (more importantly)
2545 // the time stamps. Called when we reset the GC time stamp.
2546 void G1CollectedHeap::clear_cset_start_regions() {
2547 assert(_worker_cset_start_region != NULL, "sanity");
2548 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2549
2550 for (uint i = 0; i < ParallelGCThreads; i++) {
2551 _worker_cset_start_region[i] = NULL;
2552 _worker_cset_start_region_time_stamp[i] = 0;
2553 }
2554 }
2555
2556 // Given the id of a worker, obtain or calculate a suitable
2557 // starting region for iterating over the current collection set.
2558 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2559 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2560
2561 HeapRegion* result = NULL;
2562 unsigned gc_time_stamp = get_gc_time_stamp();
2563
2564 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2565 // Cached starting region for current worker was set
2566 // during the current pause - so it's valid.
2567 // Note: the cached starting heap region may be NULL
2568 // (when the collection set is empty).
2569 result = _worker_cset_start_region[worker_i];
2570 assert(result == NULL || result->in_collection_set(), "sanity");
2571 return result;
2572 }
2573
2574 // The cached entry was not valid so let's calculate
2575 // a suitable starting heap region for this worker.
2576
2577 // We want the parallel threads to start their collection
2578 // set iteration at different collection set regions to
2579 // avoid contention.
2580 // If we have:
2581 // n collection set regions
2582 // p threads
2583 // Then thread t will start at region floor ((t * n) / p)
2584
2585 result = g1_policy()->collection_set();
2586 uint cs_size = g1_policy()->cset_region_length();
2587 uint active_workers = workers()->active_workers();
2588
2589 uint end_ind = (cs_size * worker_i) / active_workers;
2590 uint start_ind = 0;
2591
2592 if (worker_i > 0 &&
2593 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2594 // Previous workers starting region is valid
2595 // so let's iterate from there
2596 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2597 result = _worker_cset_start_region[worker_i - 1];
2598 }
2599
2600 for (uint i = start_ind; i < end_ind; i++) {
2601 result = result->next_in_collection_set();
2602 }
2603
2604 // Note: the calculated starting heap region may be NULL
2605 // (when the collection set is empty).
2606 assert(result == NULL || result->in_collection_set(), "sanity");
2607 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2608 "should be updated only once per pause");
2609 _worker_cset_start_region[worker_i] = result;
2610 OrderAccess::storestore();
2611 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2612 return result;
2613 }
2614
2615 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2616 HeapRegion* r = g1_policy()->collection_set();
2617 while (r != NULL) {
2618 HeapRegion* next = r->next_in_collection_set();
2619 if (cl->doHeapRegion(r)) {
2620 cl->incomplete();
2621 return;
2622 }
2623 r = next;
2624 }
2625 }
2626
2627 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2628 HeapRegionClosure *cl) {
2629 if (r == NULL) {
2630 // The CSet is empty so there's nothing to do.
2631 return;
2632 }
2633
2634 assert(r->in_collection_set(),
2635 "Start region must be a member of the collection set.");
2636 HeapRegion* cur = r;
2637 while (cur != NULL) {
2638 HeapRegion* next = cur->next_in_collection_set();
2639 if (cl->doHeapRegion(cur) && false) {
2640 cl->incomplete();
2641 return;
2642 }
2643 cur = next;
2644 }
2645 cur = g1_policy()->collection_set();
2646 while (cur != r) {
2647 HeapRegion* next = cur->next_in_collection_set();
2648 if (cl->doHeapRegion(cur) && false) {
2649 cl->incomplete();
2650 return;
2651 }
2652 cur = next;
2653 }
2654 }
2655
2656 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2657 HeapRegion* result = _hrm.next_region_in_heap(from);
2658 while (result != NULL && result->is_pinned()) {
2659 result = _hrm.next_region_in_heap(result);
2660 }
2661 return result;
2662 }
2663
2664 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2665 HeapRegion* hr = heap_region_containing(addr);
2666 return hr->block_start(addr);
2667 }
2668
2669 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2670 HeapRegion* hr = heap_region_containing(addr);
2671 return hr->block_size(addr);
2672 }
2673
2674 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2675 HeapRegion* hr = heap_region_containing(addr);
2676 return hr->block_is_obj(addr);
2677 }
2678
2679 bool G1CollectedHeap::supports_tlab_allocation() const {
2680 return true;
2681 }
2682
2683 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2684 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2685 }
2686
2687 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2688 return young_list()->eden_used_bytes();
2689 }
2690
2691 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2692 // must be equal to the humongous object limit.
2693 size_t G1CollectedHeap::max_tlab_size() const {
2694 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2695 }
2696
2697 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2698 AllocationContext_t context = AllocationContext::current();
2699 return _allocator->unsafe_max_tlab_alloc(context);
2700 }
2701
2702 size_t G1CollectedHeap::max_capacity() const {
2703 return _hrm.reserved().byte_size();
2704 }
2705
2706 jlong G1CollectedHeap::millis_since_last_gc() {
2707 // assert(false, "NYI");
2708 return 0;
2709 }
2710
2711 void G1CollectedHeap::prepare_for_verify() {
2712 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2713 ensure_parsability(false);
2714 }
2715 g1_rem_set()->prepare_for_verify();
2716 }
2717
2718 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2719 VerifyOption vo) {
2720 switch (vo) {
2721 case VerifyOption_G1UsePrevMarking:
2722 return hr->obj_allocated_since_prev_marking(obj);
2723 case VerifyOption_G1UseNextMarking:
2724 return hr->obj_allocated_since_next_marking(obj);
2725 case VerifyOption_G1UseMarkWord:
2726 return false;
2727 default:
2728 ShouldNotReachHere();
2729 }
2730 return false; // keep some compilers happy
2731 }
2732
2733 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2734 switch (vo) {
2735 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2736 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2737 case VerifyOption_G1UseMarkWord: return NULL;
2738 default: ShouldNotReachHere();
2739 }
2740 return NULL; // keep some compilers happy
2741 }
2742
2743 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2744 switch (vo) {
2745 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2746 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2747 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2748 default: ShouldNotReachHere();
2749 }
2750 return false; // keep some compilers happy
2751 }
2752
2753 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2754 switch (vo) {
2755 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2756 case VerifyOption_G1UseNextMarking: return "NTAMS";
2757 case VerifyOption_G1UseMarkWord: return "NONE";
2758 default: ShouldNotReachHere();
2759 }
2760 return NULL; // keep some compilers happy
2761 }
2762
2763 class VerifyRootsClosure: public OopClosure {
2764 private:
2765 G1CollectedHeap* _g1h;
2766 VerifyOption _vo;
2767 bool _failures;
2768 public:
2769 // _vo == UsePrevMarking -> use "prev" marking information,
2770 // _vo == UseNextMarking -> use "next" marking information,
2771 // _vo == UseMarkWord -> use mark word from object header.
2772 VerifyRootsClosure(VerifyOption vo) :
2773 _g1h(G1CollectedHeap::heap()),
2774 _vo(vo),
2775 _failures(false) { }
2776
2777 bool failures() { return _failures; }
2778
2779 template <class T> void do_oop_nv(T* p) {
2780 T heap_oop = oopDesc::load_heap_oop(p);
2781 if (!oopDesc::is_null(heap_oop)) {
2782 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2783 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2784 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2785 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2786 if (_vo == VerifyOption_G1UseMarkWord) {
2787 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2788 }
2789 obj->print_on(gclog_or_tty);
2790 _failures = true;
2791 }
2792 }
2793 }
2794
2795 void do_oop(oop* p) { do_oop_nv(p); }
2796 void do_oop(narrowOop* p) { do_oop_nv(p); }
2797 };
2798
2799 class G1VerifyCodeRootOopClosure: public OopClosure {
2800 G1CollectedHeap* _g1h;
2801 OopClosure* _root_cl;
2802 nmethod* _nm;
2803 VerifyOption _vo;
2804 bool _failures;
2805
2806 template <class T> void do_oop_work(T* p) {
2807 // First verify that this root is live
2808 _root_cl->do_oop(p);
2809
2810 if (!G1VerifyHeapRegionCodeRoots) {
2811 // We're not verifying the code roots attached to heap region.
2812 return;
2813 }
2814
2815 // Don't check the code roots during marking verification in a full GC
2816 if (_vo == VerifyOption_G1UseMarkWord) {
2817 return;
2818 }
2819
2820 // Now verify that the current nmethod (which contains p) is
2821 // in the code root list of the heap region containing the
2822 // object referenced by p.
2823
2824 T heap_oop = oopDesc::load_heap_oop(p);
2825 if (!oopDesc::is_null(heap_oop)) {
2826 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2827
2828 // Now fetch the region containing the object
2829 HeapRegion* hr = _g1h->heap_region_containing(obj);
2830 HeapRegionRemSet* hrrs = hr->rem_set();
2831 // Verify that the strong code root list for this region
2832 // contains the nmethod
2833 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2834 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2835 "from nmethod " PTR_FORMAT " not in strong "
2836 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2837 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2838 _failures = true;
2839 }
2840 }
2841 }
2842
2843 public:
2844 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2845 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2846
2847 void do_oop(oop* p) { do_oop_work(p); }
2848 void do_oop(narrowOop* p) { do_oop_work(p); }
2849
2850 void set_nmethod(nmethod* nm) { _nm = nm; }
2851 bool failures() { return _failures; }
2852 };
2853
2854 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2855 G1VerifyCodeRootOopClosure* _oop_cl;
2856
2857 public:
2858 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2859 _oop_cl(oop_cl) {}
2860
2861 void do_code_blob(CodeBlob* cb) {
2862 nmethod* nm = cb->as_nmethod_or_null();
2863 if (nm != NULL) {
2864 _oop_cl->set_nmethod(nm);
2865 nm->oops_do(_oop_cl);
2866 }
2867 }
2868 };
2869
2870 class YoungRefCounterClosure : public OopClosure {
2871 G1CollectedHeap* _g1h;
2872 int _count;
2873 public:
2874 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2875 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2876 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2877
2878 int count() { return _count; }
2879 void reset_count() { _count = 0; };
2880 };
2881
2882 class VerifyKlassClosure: public KlassClosure {
2883 YoungRefCounterClosure _young_ref_counter_closure;
2884 OopClosure *_oop_closure;
2885 public:
2886 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2887 void do_klass(Klass* k) {
2888 k->oops_do(_oop_closure);
2889
2890 _young_ref_counter_closure.reset_count();
2891 k->oops_do(&_young_ref_counter_closure);
2892 if (_young_ref_counter_closure.count() > 0) {
2893 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2894 }
2895 }
2896 };
2897
2898 class VerifyLivenessOopClosure: public OopClosure {
2899 G1CollectedHeap* _g1h;
2900 VerifyOption _vo;
2901 public:
2902 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2903 _g1h(g1h), _vo(vo)
2904 { }
2905 void do_oop(narrowOop *p) { do_oop_work(p); }
2906 void do_oop( oop *p) { do_oop_work(p); }
2907
2908 template <class T> void do_oop_work(T *p) {
2909 oop obj = oopDesc::load_decode_heap_oop(p);
2910 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2911 "Dead object referenced by a not dead object");
2912 }
2913 };
2914
2915 class VerifyObjsInRegionClosure: public ObjectClosure {
2916 private:
2917 G1CollectedHeap* _g1h;
2918 size_t _live_bytes;
2919 HeapRegion *_hr;
2920 VerifyOption _vo;
2921 public:
2922 // _vo == UsePrevMarking -> use "prev" marking information,
2923 // _vo == UseNextMarking -> use "next" marking information,
2924 // _vo == UseMarkWord -> use mark word from object header.
2925 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2926 : _live_bytes(0), _hr(hr), _vo(vo) {
2927 _g1h = G1CollectedHeap::heap();
2928 }
2929 void do_object(oop o) {
2930 VerifyLivenessOopClosure isLive(_g1h, _vo);
2931 assert(o != NULL, "Huh?");
2932 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2933 // If the object is alive according to the mark word,
2934 // then verify that the marking information agrees.
2935 // Note we can't verify the contra-positive of the
2936 // above: if the object is dead (according to the mark
2937 // word), it may not be marked, or may have been marked
2938 // but has since became dead, or may have been allocated
2939 // since the last marking.
2940 if (_vo == VerifyOption_G1UseMarkWord) {
2941 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2942 }
2943
2944 o->oop_iterate_no_header(&isLive);
2945 if (!_hr->obj_allocated_since_prev_marking(o)) {
2946 size_t obj_size = o->size(); // Make sure we don't overflow
2947 _live_bytes += (obj_size * HeapWordSize);
2948 }
2949 }
2950 }
2951 size_t live_bytes() { return _live_bytes; }
2952 };
2953
2954 class VerifyArchiveOopClosure: public OopClosure {
2955 public:
2956 VerifyArchiveOopClosure(HeapRegion *hr) { }
2957 void do_oop(narrowOop *p) { do_oop_work(p); }
2958 void do_oop( oop *p) { do_oop_work(p); }
2959
2960 template <class T> void do_oop_work(T *p) {
2961 oop obj = oopDesc::load_decode_heap_oop(p);
2962 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2963 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2964 p2i(p), p2i(obj));
2965 }
2966 };
2967
2968 class VerifyArchiveRegionClosure: public ObjectClosure {
2969 public:
2970 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2971 // Verify that all object pointers are to archive regions.
2972 void do_object(oop o) {
2973 VerifyArchiveOopClosure checkOop(NULL);
2974 assert(o != NULL, "Should not be here for NULL oops");
2975 o->oop_iterate_no_header(&checkOop);
2976 }
2977 };
2978
2979 class VerifyRegionClosure: public HeapRegionClosure {
2980 private:
2981 bool _par;
2982 VerifyOption _vo;
2983 bool _failures;
2984 public:
2985 // _vo == UsePrevMarking -> use "prev" marking information,
2986 // _vo == UseNextMarking -> use "next" marking information,
2987 // _vo == UseMarkWord -> use mark word from object header.
2988 VerifyRegionClosure(bool par, VerifyOption vo)
2989 : _par(par),
2990 _vo(vo),
2991 _failures(false) {}
2992
2993 bool failures() {
2994 return _failures;
2995 }
2996
2997 bool doHeapRegion(HeapRegion* r) {
2998 // For archive regions, verify there are no heap pointers to
2999 // non-pinned regions. For all others, verify liveness info.
3000 if (r->is_archive()) {
3001 VerifyArchiveRegionClosure verify_oop_pointers(r);
3002 r->object_iterate(&verify_oop_pointers);
3003 return true;
3004 }
3005 if (!r->is_continues_humongous()) {
3006 bool failures = false;
3007 r->verify(_vo, &failures);
3008 if (failures) {
3009 _failures = true;
3010 } else if (!r->is_starts_humongous()) {
3011 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3012 r->object_iterate(¬_dead_yet_cl);
3013 if (_vo != VerifyOption_G1UseNextMarking) {
3014 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3015 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3016 "max_live_bytes " SIZE_FORMAT " "
3017 "< calculated " SIZE_FORMAT,
3018 p2i(r->bottom()), p2i(r->end()),
3019 r->max_live_bytes(),
3020 not_dead_yet_cl.live_bytes());
3021 _failures = true;
3022 }
3023 } else {
3024 // When vo == UseNextMarking we cannot currently do a sanity
3025 // check on the live bytes as the calculation has not been
3026 // finalized yet.
3027 }
3028 }
3029 }
3030 return false; // stop the region iteration if we hit a failure
3031 }
3032 };
3033
3034 // This is the task used for parallel verification of the heap regions
3035
3036 class G1ParVerifyTask: public AbstractGangTask {
3037 private:
3038 G1CollectedHeap* _g1h;
3039 VerifyOption _vo;
3040 bool _failures;
3041 HeapRegionClaimer _hrclaimer;
3042
3043 public:
3044 // _vo == UsePrevMarking -> use "prev" marking information,
3045 // _vo == UseNextMarking -> use "next" marking information,
3046 // _vo == UseMarkWord -> use mark word from object header.
3047 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3048 AbstractGangTask("Parallel verify task"),
3049 _g1h(g1h),
3050 _vo(vo),
3051 _failures(false),
3052 _hrclaimer(g1h->workers()->active_workers()) {}
3053
3054 bool failures() {
3055 return _failures;
3056 }
3057
3058 void work(uint worker_id) {
3059 HandleMark hm;
3060 VerifyRegionClosure blk(true, _vo);
3061 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3062 if (blk.failures()) {
3063 _failures = true;
3064 }
3065 }
3066 };
3067
3068 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3069 if (SafepointSynchronize::is_at_safepoint()) {
3070 assert(Thread::current()->is_VM_thread(),
3071 "Expected to be executed serially by the VM thread at this point");
3072
3073 if (!silent) { gclog_or_tty->print("Roots "); }
3074 VerifyRootsClosure rootsCl(vo);
3075 VerifyKlassClosure klassCl(this, &rootsCl);
3076 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3077
3078 // We apply the relevant closures to all the oops in the
3079 // system dictionary, class loader data graph, the string table
3080 // and the nmethods in the code cache.
3081 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3082 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3083
3084 {
3085 G1RootProcessor root_processor(this, 1);
3086 root_processor.process_all_roots(&rootsCl,
3087 &cldCl,
3088 &blobsCl);
3089 }
3090
3091 bool failures = rootsCl.failures() || codeRootsCl.failures();
3092
3093 if (vo != VerifyOption_G1UseMarkWord) {
3094 // If we're verifying during a full GC then the region sets
3095 // will have been torn down at the start of the GC. Therefore
3096 // verifying the region sets will fail. So we only verify
3097 // the region sets when not in a full GC.
3098 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3099 verify_region_sets();
3100 }
3101
3102 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3103 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3104
3105 G1ParVerifyTask task(this, vo);
3106 workers()->run_task(&task);
3107 if (task.failures()) {
3108 failures = true;
3109 }
3110
3111 } else {
3112 VerifyRegionClosure blk(false, vo);
3113 heap_region_iterate(&blk);
3114 if (blk.failures()) {
3115 failures = true;
3116 }
3117 }
3118
3119 if (G1StringDedup::is_enabled()) {
3120 if (!silent) gclog_or_tty->print("StrDedup ");
3121 G1StringDedup::verify();
3122 }
3123
3124 if (failures) {
3125 gclog_or_tty->print_cr("Heap:");
3126 // It helps to have the per-region information in the output to
3127 // help us track down what went wrong. This is why we call
3128 // print_extended_on() instead of print_on().
3129 print_extended_on(gclog_or_tty);
3130 gclog_or_tty->cr();
3131 gclog_or_tty->flush();
3132 }
3133 guarantee(!failures, "there should not have been any failures");
3134 } else {
3135 if (!silent) {
3136 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3137 if (G1StringDedup::is_enabled()) {
3138 gclog_or_tty->print(", StrDedup");
3139 }
3140 gclog_or_tty->print(") ");
3141 }
3142 }
3143 }
3144
3145 void G1CollectedHeap::verify(bool silent) {
3146 verify(silent, VerifyOption_G1UsePrevMarking);
3147 }
3148
3149 double G1CollectedHeap::verify(bool guard, const char* msg) {
3150 double verify_time_ms = 0.0;
3151
3152 if (guard && total_collections() >= VerifyGCStartAt) {
3153 double verify_start = os::elapsedTime();
3154 HandleMark hm; // Discard invalid handles created during verification
3155 prepare_for_verify();
3156 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3157 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3158 }
3159
3160 return verify_time_ms;
3161 }
3162
3163 void G1CollectedHeap::verify_before_gc() {
3164 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3165 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3166 }
3167
3168 void G1CollectedHeap::verify_after_gc() {
3169 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3170 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3171 }
3172
3173 class PrintRegionClosure: public HeapRegionClosure {
3174 outputStream* _st;
3175 public:
3176 PrintRegionClosure(outputStream* st) : _st(st) {}
3177 bool doHeapRegion(HeapRegion* r) {
3178 r->print_on(_st);
3179 return false;
3180 }
3181 };
3182
3183 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3184 const HeapRegion* hr,
3185 const VerifyOption vo) const {
3186 switch (vo) {
3187 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3188 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3189 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3190 default: ShouldNotReachHere();
3191 }
3192 return false; // keep some compilers happy
3193 }
3194
3195 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3196 const VerifyOption vo) const {
3197 switch (vo) {
3198 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3199 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3200 case VerifyOption_G1UseMarkWord: {
3201 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3202 return !obj->is_gc_marked() && !hr->is_archive();
3203 }
3204 default: ShouldNotReachHere();
3205 }
3206 return false; // keep some compilers happy
3207 }
3208
3209 void G1CollectedHeap::print_on(outputStream* st) const {
3210 st->print(" %-20s", "garbage-first heap");
3211 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3212 capacity()/K, used_unlocked()/K);
3213 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3214 p2i(_hrm.reserved().start()),
3215 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3216 p2i(_hrm.reserved().end()));
3217 st->cr();
3218 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3219 uint young_regions = _young_list->length();
3220 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3221 (size_t) young_regions * HeapRegion::GrainBytes / K);
3222 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3223 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3224 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3225 st->cr();
3226 MetaspaceAux::print_on(st);
3227 }
3228
3229 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3230 print_on(st);
3231
3232 // Print the per-region information.
3233 st->cr();
3234 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3235 "HS=humongous(starts), HC=humongous(continues), "
3236 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3237 "PTAMS=previous top-at-mark-start, "
3238 "NTAMS=next top-at-mark-start)");
3239 PrintRegionClosure blk(st);
3240 heap_region_iterate(&blk);
3241 }
3242
3243 void G1CollectedHeap::print_on_error(outputStream* st) const {
3244 this->CollectedHeap::print_on_error(st);
3245
3246 if (_cm != NULL) {
3247 st->cr();
3248 _cm->print_on_error(st);
3249 }
3250 }
3251
3252 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3253 workers()->print_worker_threads_on(st);
3254 _cmThread->print_on(st);
3255 st->cr();
3256 _cm->print_worker_threads_on(st);
3257 _cg1r->print_worker_threads_on(st);
3258 if (G1StringDedup::is_enabled()) {
3259 G1StringDedup::print_worker_threads_on(st);
3260 }
3261 }
3262
3263 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3264 workers()->threads_do(tc);
3265 tc->do_thread(_cmThread);
3266 _cg1r->threads_do(tc);
3267 if (G1StringDedup::is_enabled()) {
3268 G1StringDedup::threads_do(tc);
3269 }
3270 }
3271
3272 void G1CollectedHeap::print_tracing_info() const {
3273 // We'll overload this to mean "trace GC pause statistics."
3274 if (TraceYoungGenTime || TraceOldGenTime) {
3275 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3276 // to that.
3277 g1_policy()->print_tracing_info();
3278 }
3279 if (G1SummarizeRSetStats) {
3280 g1_rem_set()->print_summary_info();
3281 }
3282 if (G1SummarizeConcMark) {
3283 concurrent_mark()->print_summary_info();
3284 }
3285 g1_policy()->print_yg_surv_rate_info();
3286 }
3287
3288 #ifndef PRODUCT
3289 // Helpful for debugging RSet issues.
3290
3291 class PrintRSetsClosure : public HeapRegionClosure {
3292 private:
3293 const char* _msg;
3294 size_t _occupied_sum;
3295
3296 public:
3297 bool doHeapRegion(HeapRegion* r) {
3298 HeapRegionRemSet* hrrs = r->rem_set();
3299 size_t occupied = hrrs->occupied();
3300 _occupied_sum += occupied;
3301
3302 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3303 HR_FORMAT_PARAMS(r));
3304 if (occupied == 0) {
3305 gclog_or_tty->print_cr(" RSet is empty");
3306 } else {
3307 hrrs->print();
3308 }
3309 gclog_or_tty->print_cr("----------");
3310 return false;
3311 }
3312
3313 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3314 gclog_or_tty->cr();
3315 gclog_or_tty->print_cr("========================================");
3316 gclog_or_tty->print_cr("%s", msg);
3317 gclog_or_tty->cr();
3318 }
3319
3320 ~PrintRSetsClosure() {
3321 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3322 gclog_or_tty->print_cr("========================================");
3323 gclog_or_tty->cr();
3324 }
3325 };
3326
3327 void G1CollectedHeap::print_cset_rsets() {
3328 PrintRSetsClosure cl("Printing CSet RSets");
3329 collection_set_iterate(&cl);
3330 }
3331
3332 void G1CollectedHeap::print_all_rsets() {
3333 PrintRSetsClosure cl("Printing All RSets");;
3334 heap_region_iterate(&cl);
3335 }
3336 #endif // PRODUCT
3337
3338 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3339 YoungList* young_list = heap()->young_list();
3340
3341 size_t eden_used_bytes = young_list->eden_used_bytes();
3342 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3343
3344 size_t eden_capacity_bytes =
3345 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3346
3347 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3348 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3349 }
3350
3351 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3352 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3353 stats->unused(), stats->used(), stats->region_end_waste(),
3354 stats->regions_filled(), stats->direct_allocated(),
3355 stats->failure_used(), stats->failure_waste());
3356 }
3357
3358 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3359 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3360 gc_tracer->report_gc_heap_summary(when, heap_summary);
3361
3362 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3363 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3364 }
3365
3366
3367 G1CollectedHeap* G1CollectedHeap::heap() {
3368 CollectedHeap* heap = Universe::heap();
3369 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3370 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3371 return (G1CollectedHeap*)heap;
3372 }
3373
3374 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3375 // always_do_update_barrier = false;
3376 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3377 // Fill TLAB's and such
3378 accumulate_statistics_all_tlabs();
3379 ensure_parsability(true);
3380
3381 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3382 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3383 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3384 }
3385 }
3386
3387 void G1CollectedHeap::gc_epilogue(bool full) {
3388
3389 if (G1SummarizeRSetStats &&
3390 (G1SummarizeRSetStatsPeriod > 0) &&
3391 // we are at the end of the GC. Total collections has already been increased.
3392 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3393 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3394 }
3395
3396 // FIXME: what is this about?
3397 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3398 // is set.
3399 #if defined(COMPILER2) || INCLUDE_JVMCI
3400 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3401 #endif
3402 // always_do_update_barrier = true;
3403
3404 resize_all_tlabs();
3405 allocation_context_stats().update(full);
3406
3407 // We have just completed a GC. Update the soft reference
3408 // policy with the new heap occupancy
3409 Universe::update_heap_info_at_gc();
3410 }
3411
3412 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3413 uint gc_count_before,
3414 bool* succeeded,
3415 GCCause::Cause gc_cause) {
3416 assert_heap_not_locked_and_not_at_safepoint();
3417 g1_policy()->record_stop_world_start();
3418 VM_G1IncCollectionPause op(gc_count_before,
3419 word_size,
3420 false, /* should_initiate_conc_mark */
3421 g1_policy()->max_pause_time_ms(),
3422 gc_cause);
3423
3424 op.set_allocation_context(AllocationContext::current());
3425 VMThread::execute(&op);
3426
3427 HeapWord* result = op.result();
3428 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3429 assert(result == NULL || ret_succeeded,
3430 "the result should be NULL if the VM did not succeed");
3431 *succeeded = ret_succeeded;
3432
3433 assert_heap_not_locked();
3434 return result;
3435 }
3436
3437 void
3438 G1CollectedHeap::doConcurrentMark() {
3439 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3440 if (!_cmThread->in_progress()) {
3441 _cmThread->set_started();
3442 CGC_lock->notify();
3443 }
3444 }
3445
3446 size_t G1CollectedHeap::pending_card_num() {
3447 size_t extra_cards = 0;
3448 JavaThread *curr = Threads::first();
3449 while (curr != NULL) {
3450 DirtyCardQueue& dcq = curr->dirty_card_queue();
3451 extra_cards += dcq.size();
3452 curr = curr->next();
3453 }
3454 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3455 size_t buffer_size = dcqs.buffer_size();
3456 size_t buffer_num = dcqs.completed_buffers_num();
3457
3458 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3459 // in bytes - not the number of 'entries'. We need to convert
3460 // into a number of cards.
3461 return (buffer_size * buffer_num + extra_cards) / oopSize;
3462 }
3463
3464 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3465 private:
3466 size_t _total_humongous;
3467 size_t _candidate_humongous;
3468
3469 DirtyCardQueue _dcq;
3470
3471 // We don't nominate objects with many remembered set entries, on
3472 // the assumption that such objects are likely still live.
3473 bool is_remset_small(HeapRegion* region) const {
3474 HeapRegionRemSet* const rset = region->rem_set();
3475 return G1EagerReclaimHumongousObjectsWithStaleRefs
3476 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3477 : rset->is_empty();
3478 }
3479
3480 bool is_typeArray_region(HeapRegion* region) const {
3481 return oop(region->bottom())->is_typeArray();
3482 }
3483
3484 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3485 assert(region->is_starts_humongous(), "Must start a humongous object");
3486
3487 // Candidate selection must satisfy the following constraints
3488 // while concurrent marking is in progress:
3489 //
3490 // * In order to maintain SATB invariants, an object must not be
3491 // reclaimed if it was allocated before the start of marking and
3492 // has not had its references scanned. Such an object must have
3493 // its references (including type metadata) scanned to ensure no
3494 // live objects are missed by the marking process. Objects
3495 // allocated after the start of concurrent marking don't need to
3496 // be scanned.
3497 //
3498 // * An object must not be reclaimed if it is on the concurrent
3499 // mark stack. Objects allocated after the start of concurrent
3500 // marking are never pushed on the mark stack.
3501 //
3502 // Nominating only objects allocated after the start of concurrent
3503 // marking is sufficient to meet both constraints. This may miss
3504 // some objects that satisfy the constraints, but the marking data
3505 // structures don't support efficiently performing the needed
3506 // additional tests or scrubbing of the mark stack.
3507 //
3508 // However, we presently only nominate is_typeArray() objects.
3509 // A humongous object containing references induces remembered
3510 // set entries on other regions. In order to reclaim such an
3511 // object, those remembered sets would need to be cleaned up.
3512 //
3513 // We also treat is_typeArray() objects specially, allowing them
3514 // to be reclaimed even if allocated before the start of
3515 // concurrent mark. For this we rely on mark stack insertion to
3516 // exclude is_typeArray() objects, preventing reclaiming an object
3517 // that is in the mark stack. We also rely on the metadata for
3518 // such objects to be built-in and so ensured to be kept live.
3519 // Frequent allocation and drop of large binary blobs is an
3520 // important use case for eager reclaim, and this special handling
3521 // may reduce needed headroom.
3522
3523 return is_typeArray_region(region) && is_remset_small(region);
3524 }
3525
3526 public:
3527 RegisterHumongousWithInCSetFastTestClosure()
3528 : _total_humongous(0),
3529 _candidate_humongous(0),
3530 _dcq(&JavaThread::dirty_card_queue_set()) {
3531 }
3532
3533 virtual bool doHeapRegion(HeapRegion* r) {
3534 if (!r->is_starts_humongous()) {
3535 return false;
3536 }
3537 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3538
3539 bool is_candidate = humongous_region_is_candidate(g1h, r);
3540 uint rindex = r->hrm_index();
3541 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3542 if (is_candidate) {
3543 _candidate_humongous++;
3544 g1h->register_humongous_region_with_cset(rindex);
3545 // Is_candidate already filters out humongous object with large remembered sets.
3546 // If we have a humongous object with a few remembered sets, we simply flush these
3547 // remembered set entries into the DCQS. That will result in automatic
3548 // re-evaluation of their remembered set entries during the following evacuation
3549 // phase.
3550 if (!r->rem_set()->is_empty()) {
3551 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3552 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3553 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3554 HeapRegionRemSetIterator hrrs(r->rem_set());
3555 size_t card_index;
3556 while (hrrs.has_next(card_index)) {
3557 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3558 // The remembered set might contain references to already freed
3559 // regions. Filter out such entries to avoid failing card table
3560 // verification.
3561 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3562 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3563 *card_ptr = CardTableModRefBS::dirty_card_val();
3564 _dcq.enqueue(card_ptr);
3565 }
3566 }
3567 }
3568 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3569 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3570 hrrs.n_yielded(), r->rem_set()->occupied());
3571 r->rem_set()->clear_locked();
3572 }
3573 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3574 }
3575 _total_humongous++;
3576
3577 return false;
3578 }
3579
3580 size_t total_humongous() const { return _total_humongous; }
3581 size_t candidate_humongous() const { return _candidate_humongous; }
3582
3583 void flush_rem_set_entries() { _dcq.flush(); }
3584 };
3585
3586 void G1CollectedHeap::register_humongous_regions_with_cset() {
3587 if (!G1EagerReclaimHumongousObjects) {
3588 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3589 return;
3590 }
3591 double time = os::elapsed_counter();
3592
3593 // Collect reclaim candidate information and register candidates with cset.
3594 RegisterHumongousWithInCSetFastTestClosure cl;
3595 heap_region_iterate(&cl);
3596
3597 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3598 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3599 cl.total_humongous(),
3600 cl.candidate_humongous());
3601 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3602
3603 // Finally flush all remembered set entries to re-check into the global DCQS.
3604 cl.flush_rem_set_entries();
3605 }
3606
3607 #ifdef ASSERT
3608 class VerifyCSetClosure: public HeapRegionClosure {
3609 public:
3610 bool doHeapRegion(HeapRegion* hr) {
3611 // Here we check that the CSet region's RSet is ready for parallel
3612 // iteration. The fields that we'll verify are only manipulated
3613 // when the region is part of a CSet and is collected. Afterwards,
3614 // we reset these fields when we clear the region's RSet (when the
3615 // region is freed) so they are ready when the region is
3616 // re-allocated. The only exception to this is if there's an
3617 // evacuation failure and instead of freeing the region we leave
3618 // it in the heap. In that case, we reset these fields during
3619 // evacuation failure handling.
3620 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3621
3622 // Here's a good place to add any other checks we'd like to
3623 // perform on CSet regions.
3624 return false;
3625 }
3626 };
3627 #endif // ASSERT
3628
3629 uint G1CollectedHeap::num_task_queues() const {
3630 return _task_queues->size();
3631 }
3632
3633 #if TASKQUEUE_STATS
3634 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3635 st->print_raw_cr("GC Task Stats");
3636 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3637 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3638 }
3639
3640 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3641 print_taskqueue_stats_hdr(st);
3642
3643 TaskQueueStats totals;
3644 const uint n = num_task_queues();
3645 for (uint i = 0; i < n; ++i) {
3646 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3647 totals += task_queue(i)->stats;
3648 }
3649 st->print_raw("tot "); totals.print(st); st->cr();
3650
3651 DEBUG_ONLY(totals.verify());
3652 }
3653
3654 void G1CollectedHeap::reset_taskqueue_stats() {
3655 const uint n = num_task_queues();
3656 for (uint i = 0; i < n; ++i) {
3657 task_queue(i)->stats.reset();
3658 }
3659 }
3660 #endif // TASKQUEUE_STATS
3661
3662 void G1CollectedHeap::log_gc_header() {
3663 if (!G1Log::fine()) {
3664 return;
3665 }
3666
3667 gclog_or_tty->gclog_stamp();
3668
3669 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3670 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3671 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3672
3673 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3674 }
3675
3676 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3677 if (!G1Log::fine()) {
3678 return;
3679 }
3680
3681 if (G1Log::finer()) {
3682 if (evacuation_failed()) {
3683 gclog_or_tty->print(" (to-space exhausted)");
3684 }
3685 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3686 g1_policy()->print_phases(pause_time_sec);
3687 g1_policy()->print_detailed_heap_transition();
3688 } else {
3689 if (evacuation_failed()) {
3690 gclog_or_tty->print("--");
3691 }
3692 g1_policy()->print_heap_transition();
3693 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3694 }
3695 gclog_or_tty->flush();
3696 }
3697
3698 void G1CollectedHeap::wait_for_root_region_scanning() {
3699 double scan_wait_start = os::elapsedTime();
3700 // We have to wait until the CM threads finish scanning the
3701 // root regions as it's the only way to ensure that all the
3702 // objects on them have been correctly scanned before we start
3703 // moving them during the GC.
3704 bool waited = _cm->root_regions()->wait_until_scan_finished();
3705 double wait_time_ms = 0.0;
3706 if (waited) {
3707 double scan_wait_end = os::elapsedTime();
3708 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3709 }
3710 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3711 }
3712
3713 bool
3714 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3715 assert_at_safepoint(true /* should_be_vm_thread */);
3716 guarantee(!is_gc_active(), "collection is not reentrant");
3717
3718 if (GC_locker::check_active_before_gc()) {
3719 return false;
3720 }
3721
3722 _gc_timer_stw->register_gc_start();
3723
3724 GCIdMark gc_id_mark;
3725 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3726
3727 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3728 ResourceMark rm;
3729
3730 wait_for_root_region_scanning();
3731
3732 G1Log::update_level();
3733 print_heap_before_gc();
3734 trace_heap_before_gc(_gc_tracer_stw);
3735
3736 verify_region_sets_optional();
3737 verify_dirty_young_regions();
3738
3739 // This call will decide whether this pause is an initial-mark
3740 // pause. If it is, during_initial_mark_pause() will return true
3741 // for the duration of this pause.
3742 g1_policy()->decide_on_conc_mark_initiation();
3743
3744 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3745 assert(!collector_state()->during_initial_mark_pause() ||
3746 collector_state()->gcs_are_young(), "sanity");
3747
3748 // We also do not allow mixed GCs during marking.
3749 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3750
3751 // Record whether this pause is an initial mark. When the current
3752 // thread has completed its logging output and it's safe to signal
3753 // the CM thread, the flag's value in the policy has been reset.
3754 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3755
3756 // Inner scope for scope based logging, timers, and stats collection
3757 {
3758 EvacuationInfo evacuation_info;
3759
3760 if (collector_state()->during_initial_mark_pause()) {
3761 // We are about to start a marking cycle, so we increment the
3762 // full collection counter.
3763 increment_old_marking_cycles_started();
3764 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3765 }
3766
3767 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3768
3769 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3770
3771 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3772 workers()->active_workers(),
3773 Threads::number_of_non_daemon_threads());
3774 workers()->set_active_workers(active_workers);
3775
3776 double pause_start_sec = os::elapsedTime();
3777 g1_policy()->note_gc_start(active_workers);
3778 log_gc_header();
3779
3780 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3781 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3782
3783 // If the secondary_free_list is not empty, append it to the
3784 // free_list. No need to wait for the cleanup operation to finish;
3785 // the region allocation code will check the secondary_free_list
3786 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3787 // set, skip this step so that the region allocation code has to
3788 // get entries from the secondary_free_list.
3789 if (!G1StressConcRegionFreeing) {
3790 append_secondary_free_list_if_not_empty_with_lock();
3791 }
3792
3793 assert(check_young_list_well_formed(), "young list should be well formed");
3794
3795 // Don't dynamically change the number of GC threads this early. A value of
3796 // 0 is used to indicate serial work. When parallel work is done,
3797 // it will be set.
3798
3799 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3800 IsGCActiveMark x;
3801
3802 gc_prologue(false);
3803 increment_total_collections(false /* full gc */);
3804 increment_gc_time_stamp();
3805
3806 verify_before_gc();
3807
3808 check_bitmaps("GC Start");
3809
3810 #if defined(COMPILER2) || INCLUDE_JVMCI
3811 DerivedPointerTable::clear();
3812 #endif
3813
3814 // Please see comment in g1CollectedHeap.hpp and
3815 // G1CollectedHeap::ref_processing_init() to see how
3816 // reference processing currently works in G1.
3817
3818 // Enable discovery in the STW reference processor
3819 ref_processor_stw()->enable_discovery();
3820
3821 {
3822 // We want to temporarily turn off discovery by the
3823 // CM ref processor, if necessary, and turn it back on
3824 // on again later if we do. Using a scoped
3825 // NoRefDiscovery object will do this.
3826 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3827
3828 // Forget the current alloc region (we might even choose it to be part
3829 // of the collection set!).
3830 _allocator->release_mutator_alloc_region();
3831
3832 // We should call this after we retire the mutator alloc
3833 // region(s) so that all the ALLOC / RETIRE events are generated
3834 // before the start GC event.
3835 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3836
3837 // This timing is only used by the ergonomics to handle our pause target.
3838 // It is unclear why this should not include the full pause. We will
3839 // investigate this in CR 7178365.
3840 //
3841 // Preserving the old comment here if that helps the investigation:
3842 //
3843 // The elapsed time induced by the start time below deliberately elides
3844 // the possible verification above.
3845 double sample_start_time_sec = os::elapsedTime();
3846
3847 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3848
3849 if (collector_state()->during_initial_mark_pause()) {
3850 concurrent_mark()->checkpointRootsInitialPre();
3851 }
3852
3853 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3854 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3855
3856 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3857
3858 // Make sure the remembered sets are up to date. This needs to be
3859 // done before register_humongous_regions_with_cset(), because the
3860 // remembered sets are used there to choose eager reclaim candidates.
3861 // If the remembered sets are not up to date we might miss some
3862 // entries that need to be handled.
3863 g1_rem_set()->cleanupHRRS();
3864
3865 register_humongous_regions_with_cset();
3866
3867 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3868
3869 _cm->note_start_of_gc();
3870 // We call this after finalize_cset() to
3871 // ensure that the CSet has been finalized.
3872 _cm->verify_no_cset_oops();
3873
3874 if (_hr_printer.is_active()) {
3875 HeapRegion* hr = g1_policy()->collection_set();
3876 while (hr != NULL) {
3877 _hr_printer.cset(hr);
3878 hr = hr->next_in_collection_set();
3879 }
3880 }
3881
3882 #ifdef ASSERT
3883 VerifyCSetClosure cl;
3884 collection_set_iterate(&cl);
3885 #endif // ASSERT
3886
3887 // Initialize the GC alloc regions.
3888 _allocator->init_gc_alloc_regions(evacuation_info);
3889
3890 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3891 pre_evacuate_collection_set();
3892
3893 // Actually do the work...
3894 evacuate_collection_set(evacuation_info, &per_thread_states);
3895
3896 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3897
3898 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3899 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3900
3901 eagerly_reclaim_humongous_regions();
3902
3903 g1_policy()->clear_collection_set();
3904
3905 // Start a new incremental collection set for the next pause.
3906 g1_policy()->start_incremental_cset_building();
3907
3908 clear_cset_fast_test();
3909
3910 _young_list->reset_sampled_info();
3911
3912 // Don't check the whole heap at this point as the
3913 // GC alloc regions from this pause have been tagged
3914 // as survivors and moved on to the survivor list.
3915 // Survivor regions will fail the !is_young() check.
3916 assert(check_young_list_empty(false /* check_heap */),
3917 "young list should be empty");
3918
3919 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3920 _young_list->first_survivor_region(),
3921 _young_list->last_survivor_region());
3922
3923 _young_list->reset_auxilary_lists();
3924
3925 if (evacuation_failed()) {
3926 set_used(recalculate_used());
3927 if (_archive_allocator != NULL) {
3928 _archive_allocator->clear_used();
3929 }
3930 for (uint i = 0; i < ParallelGCThreads; i++) {
3931 if (_evacuation_failed_info_array[i].has_failed()) {
3932 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3933 }
3934 }
3935 } else {
3936 // The "used" of the the collection set have already been subtracted
3937 // when they were freed. Add in the bytes evacuated.
3938 increase_used(g1_policy()->bytes_copied_during_gc());
3939 }
3940
3941 if (collector_state()->during_initial_mark_pause()) {
3942 // We have to do this before we notify the CM threads that
3943 // they can start working to make sure that all the
3944 // appropriate initialization is done on the CM object.
3945 concurrent_mark()->checkpointRootsInitialPost();
3946 collector_state()->set_mark_in_progress(true);
3947 // Note that we don't actually trigger the CM thread at
3948 // this point. We do that later when we're sure that
3949 // the current thread has completed its logging output.
3950 }
3951
3952 allocate_dummy_regions();
3953
3954 _allocator->init_mutator_alloc_region();
3955
3956 {
3957 size_t expand_bytes = g1_policy()->expansion_amount();
3958 if (expand_bytes > 0) {
3959 size_t bytes_before = capacity();
3960 // No need for an ergo verbose message here,
3961 // expansion_amount() does this when it returns a value > 0.
3962 double expand_ms;
3963 if (!expand(expand_bytes, &expand_ms)) {
3964 // We failed to expand the heap. Cannot do anything about it.
3965 }
3966 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3967 }
3968 }
3969
3970 // We redo the verification but now wrt to the new CSet which
3971 // has just got initialized after the previous CSet was freed.
3972 _cm->verify_no_cset_oops();
3973 _cm->note_end_of_gc();
3974
3975 // This timing is only used by the ergonomics to handle our pause target.
3976 // It is unclear why this should not include the full pause. We will
3977 // investigate this in CR 7178365.
3978 double sample_end_time_sec = os::elapsedTime();
3979 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3980 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3981 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3982
3983 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3984 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3985
3986 MemoryService::track_memory_usage();
3987
3988 // In prepare_for_verify() below we'll need to scan the deferred
3989 // update buffers to bring the RSets up-to-date if
3990 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3991 // the update buffers we'll probably need to scan cards on the
3992 // regions we just allocated to (i.e., the GC alloc
3993 // regions). However, during the last GC we called
3994 // set_saved_mark() on all the GC alloc regions, so card
3995 // scanning might skip the [saved_mark_word()...top()] area of
3996 // those regions (i.e., the area we allocated objects into
3997 // during the last GC). But it shouldn't. Given that
3998 // saved_mark_word() is conditional on whether the GC time stamp
3999 // on the region is current or not, by incrementing the GC time
4000 // stamp here we invalidate all the GC time stamps on all the
4001 // regions and saved_mark_word() will simply return top() for
4002 // all the regions. This is a nicer way of ensuring this rather
4003 // than iterating over the regions and fixing them. In fact, the
4004 // GC time stamp increment here also ensures that
4005 // saved_mark_word() will return top() between pauses, i.e.,
4006 // during concurrent refinement. So we don't need the
4007 // is_gc_active() check to decided which top to use when
4008 // scanning cards (see CR 7039627).
4009 increment_gc_time_stamp();
4010
4011 verify_after_gc();
4012 check_bitmaps("GC End");
4013
4014 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4015 ref_processor_stw()->verify_no_references_recorded();
4016
4017 // CM reference discovery will be re-enabled if necessary.
4018 }
4019
4020 // We should do this after we potentially expand the heap so
4021 // that all the COMMIT events are generated before the end GC
4022 // event, and after we retire the GC alloc regions so that all
4023 // RETIRE events are generated before the end GC event.
4024 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4025
4026 #ifdef TRACESPINNING
4027 ParallelTaskTerminator::print_termination_counts();
4028 #endif
4029
4030 gc_epilogue(false);
4031 }
4032
4033 // Print the remainder of the GC log output.
4034 log_gc_footer(os::elapsedTime() - pause_start_sec);
4035
4036 // It is not yet to safe to tell the concurrent mark to
4037 // start as we have some optional output below. We don't want the
4038 // output from the concurrent mark thread interfering with this
4039 // logging output either.
4040
4041 _hrm.verify_optional();
4042 verify_region_sets_optional();
4043
4044 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4045 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4046
4047 print_heap_after_gc();
4048 trace_heap_after_gc(_gc_tracer_stw);
4049
4050 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4051 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4052 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4053 // before any GC notifications are raised.
4054 g1mm()->update_sizes();
4055
4056 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4057 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4058 _gc_timer_stw->register_gc_end();
4059 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4060 }
4061 // It should now be safe to tell the concurrent mark thread to start
4062 // without its logging output interfering with the logging output
4063 // that came from the pause.
4064
4065 if (should_start_conc_mark) {
4066 // CAUTION: after the doConcurrentMark() call below,
4067 // the concurrent marking thread(s) could be running
4068 // concurrently with us. Make sure that anything after
4069 // this point does not assume that we are the only GC thread
4070 // running. Note: of course, the actual marking work will
4071 // not start until the safepoint itself is released in
4072 // SuspendibleThreadSet::desynchronize().
4073 doConcurrentMark();
4074 }
4075
4076 return true;
4077 }
4078
4079 void G1CollectedHeap::remove_self_forwarding_pointers() {
4080 double remove_self_forwards_start = os::elapsedTime();
4081
4082 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4083 workers()->run_task(&rsfp_task);
4084
4085 // Now restore saved marks, if any.
4086 for (uint i = 0; i < ParallelGCThreads; i++) {
4087 OopAndMarkOopStack& cur = _preserved_objs[i];
4088 while (!cur.is_empty()) {
4089 OopAndMarkOop elem = cur.pop();
4090 elem.set_mark();
4091 }
4092 cur.clear(true);
4093 }
4094
4095 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4096 }
4097
4098 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4099 if (!_evacuation_failed) {
4100 _evacuation_failed = true;
4101 }
4102
4103 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4104
4105 // We want to call the "for_promotion_failure" version only in the
4106 // case of a promotion failure.
4107 if (m->must_be_preserved_for_promotion_failure(obj)) {
4108 OopAndMarkOop elem(obj, m);
4109 _preserved_objs[worker_id].push(elem);
4110 }
4111 }
4112
4113 class G1ParEvacuateFollowersClosure : public VoidClosure {
4114 private:
4115 double _start_term;
4116 double _term_time;
4117 size_t _term_attempts;
4118
4119 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4120 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4121 protected:
4122 G1CollectedHeap* _g1h;
4123 G1ParScanThreadState* _par_scan_state;
4124 RefToScanQueueSet* _queues;
4125 ParallelTaskTerminator* _terminator;
4126
4127 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4128 RefToScanQueueSet* queues() { return _queues; }
4129 ParallelTaskTerminator* terminator() { return _terminator; }
4130
4131 public:
4132 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4133 G1ParScanThreadState* par_scan_state,
4134 RefToScanQueueSet* queues,
4135 ParallelTaskTerminator* terminator)
4136 : _g1h(g1h), _par_scan_state(par_scan_state),
4137 _queues(queues), _terminator(terminator),
4138 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4139
4140 void do_void();
4141
4142 double term_time() const { return _term_time; }
4143 size_t term_attempts() const { return _term_attempts; }
4144
4145 private:
4146 inline bool offer_termination();
4147 };
4148
4149 bool G1ParEvacuateFollowersClosure::offer_termination() {
4150 G1ParScanThreadState* const pss = par_scan_state();
4151 start_term_time();
4152 const bool res = terminator()->offer_termination();
4153 end_term_time();
4154 return res;
4155 }
4156
4157 void G1ParEvacuateFollowersClosure::do_void() {
4158 G1ParScanThreadState* const pss = par_scan_state();
4159 pss->trim_queue();
4160 do {
4161 pss->steal_and_trim_queue(queues());
4162 } while (!offer_termination());
4163 }
4164
4165 class G1ParTask : public AbstractGangTask {
4166 protected:
4167 G1CollectedHeap* _g1h;
4168 G1ParScanThreadStateSet* _pss;
4169 RefToScanQueueSet* _queues;
4170 G1RootProcessor* _root_processor;
4171 ParallelTaskTerminator _terminator;
4172 uint _n_workers;
4173
4174 public:
4175 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4176 : AbstractGangTask("G1 collection"),
4177 _g1h(g1h),
4178 _pss(per_thread_states),
4179 _queues(task_queues),
4180 _root_processor(root_processor),
4181 _terminator(n_workers, _queues),
4182 _n_workers(n_workers)
4183 {}
4184
4185 void work(uint worker_id) {
4186 if (worker_id >= _n_workers) return; // no work needed this round
4187
4188 double start_sec = os::elapsedTime();
4189 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4190
4191 {
4192 ResourceMark rm;
4193 HandleMark hm;
4194
4195 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4196
4197 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4198 pss->set_ref_processor(rp);
4199
4200 double start_strong_roots_sec = os::elapsedTime();
4201
4202 _root_processor->evacuate_roots(pss->closures(), worker_id);
4203
4204 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4205
4206 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4207 // treating the nmethods visited to act as roots for concurrent marking.
4208 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4209 // objects copied by the current evacuation.
4210 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4211 pss->closures()->weak_codeblobs(),
4212 worker_id);
4213
4214 _pss->add_cards_scanned(worker_id, cards_scanned);
4215
4216 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4217
4218 double term_sec = 0.0;
4219 size_t evac_term_attempts = 0;
4220 {
4221 double start = os::elapsedTime();
4222 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4223 evac.do_void();
4224
4225 evac_term_attempts = evac.term_attempts();
4226 term_sec = evac.term_time();
4227 double elapsed_sec = os::elapsedTime() - start;
4228 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4229 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4230 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4231 }
4232
4233 assert(pss->queue_is_empty(), "should be empty");
4234
4235 if (PrintTerminationStats) {
4236 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4237 size_t lab_waste;
4238 size_t lab_undo_waste;
4239 pss->waste(lab_waste, lab_undo_waste);
4240 _g1h->print_termination_stats(gclog_or_tty,
4241 worker_id,
4242 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4243 strong_roots_sec * 1000.0, /* strong roots time */
4244 term_sec * 1000.0, /* evac term time */
4245 evac_term_attempts, /* evac term attempts */
4246 lab_waste, /* alloc buffer waste */
4247 lab_undo_waste /* undo waste */
4248 );
4249 }
4250
4251 // Close the inner scope so that the ResourceMark and HandleMark
4252 // destructors are executed here and are included as part of the
4253 // "GC Worker Time".
4254 }
4255 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4256 }
4257 };
4258
4259 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4260 st->print_raw_cr("GC Termination Stats");
4261 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4262 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4263 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4264 }
4265
4266 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4267 uint worker_id,
4268 double elapsed_ms,
4269 double strong_roots_ms,
4270 double term_ms,
4271 size_t term_attempts,
4272 size_t alloc_buffer_waste,
4273 size_t undo_waste) const {
4274 st->print_cr("%3d %9.2f %9.2f %6.2f "
4275 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4276 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4277 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4278 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4279 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4280 alloc_buffer_waste * HeapWordSize / K,
4281 undo_waste * HeapWordSize / K);
4282 }
4283
4284 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4285 private:
4286 BoolObjectClosure* _is_alive;
4287 int _initial_string_table_size;
4288 int _initial_symbol_table_size;
4289
4290 bool _process_strings;
4291 int _strings_processed;
4292 int _strings_removed;
4293
4294 bool _process_symbols;
4295 int _symbols_processed;
4296 int _symbols_removed;
4297
4298 public:
4299 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4300 AbstractGangTask("String/Symbol Unlinking"),
4301 _is_alive(is_alive),
4302 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4303 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4304
4305 _initial_string_table_size = StringTable::the_table()->table_size();
4306 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4307 if (process_strings) {
4308 StringTable::clear_parallel_claimed_index();
4309 }
4310 if (process_symbols) {
4311 SymbolTable::clear_parallel_claimed_index();
4312 }
4313 }
4314
4315 ~G1StringSymbolTableUnlinkTask() {
4316 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4317 "claim value %d after unlink less than initial string table size %d",
4318 StringTable::parallel_claimed_index(), _initial_string_table_size);
4319 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4320 "claim value %d after unlink less than initial symbol table size %d",
4321 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4322
4323 if (G1TraceStringSymbolTableScrubbing) {
4324 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4325 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4326 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4327 strings_processed(), strings_removed(),
4328 symbols_processed(), symbols_removed());
4329 }
4330 }
4331
4332 void work(uint worker_id) {
4333 int strings_processed = 0;
4334 int strings_removed = 0;
4335 int symbols_processed = 0;
4336 int symbols_removed = 0;
4337 if (_process_strings) {
4338 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4339 Atomic::add(strings_processed, &_strings_processed);
4340 Atomic::add(strings_removed, &_strings_removed);
4341 }
4342 if (_process_symbols) {
4343 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4344 Atomic::add(symbols_processed, &_symbols_processed);
4345 Atomic::add(symbols_removed, &_symbols_removed);
4346 }
4347 }
4348
4349 size_t strings_processed() const { return (size_t)_strings_processed; }
4350 size_t strings_removed() const { return (size_t)_strings_removed; }
4351
4352 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4353 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4354 };
4355
4356 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4357 private:
4358 static Monitor* _lock;
4359
4360 BoolObjectClosure* const _is_alive;
4361 const bool _unloading_occurred;
4362 const uint _num_workers;
4363
4364 // Variables used to claim nmethods.
4365 nmethod* _first_nmethod;
4366 volatile nmethod* _claimed_nmethod;
4367
4368 // The list of nmethods that need to be processed by the second pass.
4369 volatile nmethod* _postponed_list;
4370 volatile uint _num_entered_barrier;
4371
4372 public:
4373 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4374 _is_alive(is_alive),
4375 _unloading_occurred(unloading_occurred),
4376 _num_workers(num_workers),
4377 _first_nmethod(NULL),
4378 _claimed_nmethod(NULL),
4379 _postponed_list(NULL),
4380 _num_entered_barrier(0)
4381 {
4382 nmethod::increase_unloading_clock();
4383 // Get first alive nmethod
4384 NMethodIterator iter = NMethodIterator();
4385 if(iter.next_alive()) {
4386 _first_nmethod = iter.method();
4387 }
4388 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4389 }
4390
4391 ~G1CodeCacheUnloadingTask() {
4392 CodeCache::verify_clean_inline_caches();
4393
4394 CodeCache::set_needs_cache_clean(false);
4395 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4396
4397 CodeCache::verify_icholder_relocations();
4398 }
4399
4400 private:
4401 void add_to_postponed_list(nmethod* nm) {
4402 nmethod* old;
4403 do {
4404 old = (nmethod*)_postponed_list;
4405 nm->set_unloading_next(old);
4406 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4407 }
4408
4409 void clean_nmethod(nmethod* nm) {
4410 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4411
4412 if (postponed) {
4413 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4414 add_to_postponed_list(nm);
4415 }
4416
4417 // Mark that this thread has been cleaned/unloaded.
4418 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4419 nm->set_unloading_clock(nmethod::global_unloading_clock());
4420 }
4421
4422 void clean_nmethod_postponed(nmethod* nm) {
4423 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4424 }
4425
4426 static const int MaxClaimNmethods = 16;
4427
4428 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4429 nmethod* first;
4430 NMethodIterator last;
4431
4432 do {
4433 *num_claimed_nmethods = 0;
4434
4435 first = (nmethod*)_claimed_nmethod;
4436 last = NMethodIterator(first);
4437
4438 if (first != NULL) {
4439
4440 for (int i = 0; i < MaxClaimNmethods; i++) {
4441 if (!last.next_alive()) {
4442 break;
4443 }
4444 claimed_nmethods[i] = last.method();
4445 (*num_claimed_nmethods)++;
4446 }
4447 }
4448
4449 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4450 }
4451
4452 nmethod* claim_postponed_nmethod() {
4453 nmethod* claim;
4454 nmethod* next;
4455
4456 do {
4457 claim = (nmethod*)_postponed_list;
4458 if (claim == NULL) {
4459 return NULL;
4460 }
4461
4462 next = claim->unloading_next();
4463
4464 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4465
4466 return claim;
4467 }
4468
4469 public:
4470 // Mark that we're done with the first pass of nmethod cleaning.
4471 void barrier_mark(uint worker_id) {
4472 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4473 _num_entered_barrier++;
4474 if (_num_entered_barrier == _num_workers) {
4475 ml.notify_all();
4476 }
4477 }
4478
4479 // See if we have to wait for the other workers to
4480 // finish their first-pass nmethod cleaning work.
4481 void barrier_wait(uint worker_id) {
4482 if (_num_entered_barrier < _num_workers) {
4483 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4484 while (_num_entered_barrier < _num_workers) {
4485 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4486 }
4487 }
4488 }
4489
4490 // Cleaning and unloading of nmethods. Some work has to be postponed
4491 // to the second pass, when we know which nmethods survive.
4492 void work_first_pass(uint worker_id) {
4493 // The first nmethods is claimed by the first worker.
4494 if (worker_id == 0 && _first_nmethod != NULL) {
4495 clean_nmethod(_first_nmethod);
4496 _first_nmethod = NULL;
4497 }
4498
4499 int num_claimed_nmethods;
4500 nmethod* claimed_nmethods[MaxClaimNmethods];
4501
4502 while (true) {
4503 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4504
4505 if (num_claimed_nmethods == 0) {
4506 break;
4507 }
4508
4509 for (int i = 0; i < num_claimed_nmethods; i++) {
4510 clean_nmethod(claimed_nmethods[i]);
4511 }
4512 }
4513 }
4514
4515 void work_second_pass(uint worker_id) {
4516 nmethod* nm;
4517 // Take care of postponed nmethods.
4518 while ((nm = claim_postponed_nmethod()) != NULL) {
4519 clean_nmethod_postponed(nm);
4520 }
4521 }
4522 };
4523
4524 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4525
4526 class G1KlassCleaningTask : public StackObj {
4527 BoolObjectClosure* _is_alive;
4528 volatile jint _clean_klass_tree_claimed;
4529 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4530
4531 public:
4532 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4533 _is_alive(is_alive),
4534 _clean_klass_tree_claimed(0),
4535 _klass_iterator() {
4536 }
4537
4538 private:
4539 bool claim_clean_klass_tree_task() {
4540 if (_clean_klass_tree_claimed) {
4541 return false;
4542 }
4543
4544 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4545 }
4546
4547 InstanceKlass* claim_next_klass() {
4548 Klass* klass;
4549 do {
4550 klass =_klass_iterator.next_klass();
4551 } while (klass != NULL && !klass->is_instance_klass());
4552
4553 // this can be null so don't call InstanceKlass::cast
4554 return static_cast<InstanceKlass*>(klass);
4555 }
4556
4557 public:
4558
4559 void clean_klass(InstanceKlass* ik) {
4560 ik->clean_weak_instanceklass_links(_is_alive);
4561 }
4562
4563 void work() {
4564 ResourceMark rm;
4565
4566 // One worker will clean the subklass/sibling klass tree.
4567 if (claim_clean_klass_tree_task()) {
4568 Klass::clean_subklass_tree(_is_alive);
4569 }
4570
4571 // All workers will help cleaning the classes,
4572 InstanceKlass* klass;
4573 while ((klass = claim_next_klass()) != NULL) {
4574 clean_klass(klass);
4575 }
4576 }
4577 };
4578
4579 // To minimize the remark pause times, the tasks below are done in parallel.
4580 class G1ParallelCleaningTask : public AbstractGangTask {
4581 private:
4582 G1StringSymbolTableUnlinkTask _string_symbol_task;
4583 G1CodeCacheUnloadingTask _code_cache_task;
4584 G1KlassCleaningTask _klass_cleaning_task;
4585
4586 public:
4587 // The constructor is run in the VMThread.
4588 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4589 AbstractGangTask("Parallel Cleaning"),
4590 _string_symbol_task(is_alive, process_strings, process_symbols),
4591 _code_cache_task(num_workers, is_alive, unloading_occurred),
4592 _klass_cleaning_task(is_alive) {
4593 }
4594
4595 // The parallel work done by all worker threads.
4596 void work(uint worker_id) {
4597 // Do first pass of code cache cleaning.
4598 _code_cache_task.work_first_pass(worker_id);
4599
4600 // Let the threads mark that the first pass is done.
4601 _code_cache_task.barrier_mark(worker_id);
4602
4603 // Clean the Strings and Symbols.
4604 _string_symbol_task.work(worker_id);
4605
4606 // Wait for all workers to finish the first code cache cleaning pass.
4607 _code_cache_task.barrier_wait(worker_id);
4608
4609 // Do the second code cache cleaning work, which realize on
4610 // the liveness information gathered during the first pass.
4611 _code_cache_task.work_second_pass(worker_id);
4612
4613 // Clean all klasses that were not unloaded.
4614 _klass_cleaning_task.work();
4615 }
4616 };
4617
4618
4619 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4620 bool process_strings,
4621 bool process_symbols,
4622 bool class_unloading_occurred) {
4623 uint n_workers = workers()->active_workers();
4624
4625 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4626 n_workers, class_unloading_occurred);
4627 workers()->run_task(&g1_unlink_task);
4628 }
4629
4630 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4631 bool process_strings, bool process_symbols) {
4632 {
4633 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4634 workers()->run_task(&g1_unlink_task);
4635 }
4636
4637 if (G1StringDedup::is_enabled()) {
4638 G1StringDedup::unlink(is_alive);
4639 }
4640 }
4641
4642 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4643 private:
4644 DirtyCardQueueSet* _queue;
4645 public:
4646 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4647
4648 virtual void work(uint worker_id) {
4649 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4650 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4651
4652 RedirtyLoggedCardTableEntryClosure cl;
4653 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4654
4655 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4656 }
4657 };
4658
4659 void G1CollectedHeap::redirty_logged_cards() {
4660 double redirty_logged_cards_start = os::elapsedTime();
4661
4662 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4663 dirty_card_queue_set().reset_for_par_iteration();
4664 workers()->run_task(&redirty_task);
4665
4666 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4667 dcq.merge_bufferlists(&dirty_card_queue_set());
4668 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4669
4670 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4671 }
4672
4673 // Weak Reference Processing support
4674
4675 // An always "is_alive" closure that is used to preserve referents.
4676 // If the object is non-null then it's alive. Used in the preservation
4677 // of referent objects that are pointed to by reference objects
4678 // discovered by the CM ref processor.
4679 class G1AlwaysAliveClosure: public BoolObjectClosure {
4680 G1CollectedHeap* _g1;
4681 public:
4682 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4683 bool do_object_b(oop p) {
4684 if (p != NULL) {
4685 return true;
4686 }
4687 return false;
4688 }
4689 };
4690
4691 bool G1STWIsAliveClosure::do_object_b(oop p) {
4692 // An object is reachable if it is outside the collection set,
4693 // or is inside and copied.
4694 return !_g1->is_in_cset(p) || p->is_forwarded();
4695 }
4696
4697 // Non Copying Keep Alive closure
4698 class G1KeepAliveClosure: public OopClosure {
4699 G1CollectedHeap* _g1;
4700 public:
4701 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4702 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4703 void do_oop(oop* p) {
4704 oop obj = *p;
4705 assert(obj != NULL, "the caller should have filtered out NULL values");
4706
4707 const InCSetState cset_state = _g1->in_cset_state(obj);
4708 if (!cset_state.is_in_cset_or_humongous()) {
4709 return;
4710 }
4711 if (cset_state.is_in_cset()) {
4712 assert( obj->is_forwarded(), "invariant" );
4713 *p = obj->forwardee();
4714 } else {
4715 assert(!obj->is_forwarded(), "invariant" );
4716 assert(cset_state.is_humongous(),
4717 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4718 _g1->set_humongous_is_live(obj);
4719 }
4720 }
4721 };
4722
4723 // Copying Keep Alive closure - can be called from both
4724 // serial and parallel code as long as different worker
4725 // threads utilize different G1ParScanThreadState instances
4726 // and different queues.
4727
4728 class G1CopyingKeepAliveClosure: public OopClosure {
4729 G1CollectedHeap* _g1h;
4730 OopClosure* _copy_non_heap_obj_cl;
4731 G1ParScanThreadState* _par_scan_state;
4732
4733 public:
4734 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4735 OopClosure* non_heap_obj_cl,
4736 G1ParScanThreadState* pss):
4737 _g1h(g1h),
4738 _copy_non_heap_obj_cl(non_heap_obj_cl),
4739 _par_scan_state(pss)
4740 {}
4741
4742 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4743 virtual void do_oop( oop* p) { do_oop_work(p); }
4744
4745 template <class T> void do_oop_work(T* p) {
4746 oop obj = oopDesc::load_decode_heap_oop(p);
4747
4748 if (_g1h->is_in_cset_or_humongous(obj)) {
4749 // If the referent object has been forwarded (either copied
4750 // to a new location or to itself in the event of an
4751 // evacuation failure) then we need to update the reference
4752 // field and, if both reference and referent are in the G1
4753 // heap, update the RSet for the referent.
4754 //
4755 // If the referent has not been forwarded then we have to keep
4756 // it alive by policy. Therefore we have copy the referent.
4757 //
4758 // If the reference field is in the G1 heap then we can push
4759 // on the PSS queue. When the queue is drained (after each
4760 // phase of reference processing) the object and it's followers
4761 // will be copied, the reference field set to point to the
4762 // new location, and the RSet updated. Otherwise we need to
4763 // use the the non-heap or metadata closures directly to copy
4764 // the referent object and update the pointer, while avoiding
4765 // updating the RSet.
4766
4767 if (_g1h->is_in_g1_reserved(p)) {
4768 _par_scan_state->push_on_queue(p);
4769 } else {
4770 assert(!Metaspace::contains((const void*)p),
4771 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4772 _copy_non_heap_obj_cl->do_oop(p);
4773 }
4774 }
4775 }
4776 };
4777
4778 // Serial drain queue closure. Called as the 'complete_gc'
4779 // closure for each discovered list in some of the
4780 // reference processing phases.
4781
4782 class G1STWDrainQueueClosure: public VoidClosure {
4783 protected:
4784 G1CollectedHeap* _g1h;
4785 G1ParScanThreadState* _par_scan_state;
4786
4787 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4788
4789 public:
4790 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4791 _g1h(g1h),
4792 _par_scan_state(pss)
4793 { }
4794
4795 void do_void() {
4796 G1ParScanThreadState* const pss = par_scan_state();
4797 pss->trim_queue();
4798 }
4799 };
4800
4801 // Parallel Reference Processing closures
4802
4803 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4804 // processing during G1 evacuation pauses.
4805
4806 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4807 private:
4808 G1CollectedHeap* _g1h;
4809 G1ParScanThreadStateSet* _pss;
4810 RefToScanQueueSet* _queues;
4811 WorkGang* _workers;
4812 uint _active_workers;
4813
4814 public:
4815 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4816 G1ParScanThreadStateSet* per_thread_states,
4817 WorkGang* workers,
4818 RefToScanQueueSet *task_queues,
4819 uint n_workers) :
4820 _g1h(g1h),
4821 _pss(per_thread_states),
4822 _queues(task_queues),
4823 _workers(workers),
4824 _active_workers(n_workers)
4825 {
4826 assert(n_workers > 0, "shouldn't call this otherwise");
4827 }
4828
4829 // Executes the given task using concurrent marking worker threads.
4830 virtual void execute(ProcessTask& task);
4831 virtual void execute(EnqueueTask& task);
4832 };
4833
4834 // Gang task for possibly parallel reference processing
4835
4836 class G1STWRefProcTaskProxy: public AbstractGangTask {
4837 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4838 ProcessTask& _proc_task;
4839 G1CollectedHeap* _g1h;
4840 G1ParScanThreadStateSet* _pss;
4841 RefToScanQueueSet* _task_queues;
4842 ParallelTaskTerminator* _terminator;
4843
4844 public:
4845 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4846 G1CollectedHeap* g1h,
4847 G1ParScanThreadStateSet* per_thread_states,
4848 RefToScanQueueSet *task_queues,
4849 ParallelTaskTerminator* terminator) :
4850 AbstractGangTask("Process reference objects in parallel"),
4851 _proc_task(proc_task),
4852 _g1h(g1h),
4853 _pss(per_thread_states),
4854 _task_queues(task_queues),
4855 _terminator(terminator)
4856 {}
4857
4858 virtual void work(uint worker_id) {
4859 // The reference processing task executed by a single worker.
4860 ResourceMark rm;
4861 HandleMark hm;
4862
4863 G1STWIsAliveClosure is_alive(_g1h);
4864
4865 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4866 pss->set_ref_processor(NULL);
4867
4868 // Keep alive closure.
4869 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4870
4871 // Complete GC closure
4872 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4873
4874 // Call the reference processing task's work routine.
4875 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4876
4877 // Note we cannot assert that the refs array is empty here as not all
4878 // of the processing tasks (specifically phase2 - pp2_work) execute
4879 // the complete_gc closure (which ordinarily would drain the queue) so
4880 // the queue may not be empty.
4881 }
4882 };
4883
4884 // Driver routine for parallel reference processing.
4885 // Creates an instance of the ref processing gang
4886 // task and has the worker threads execute it.
4887 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4888 assert(_workers != NULL, "Need parallel worker threads.");
4889
4890 ParallelTaskTerminator terminator(_active_workers, _queues);
4891 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4892
4893 _workers->run_task(&proc_task_proxy);
4894 }
4895
4896 // Gang task for parallel reference enqueueing.
4897
4898 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4899 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4900 EnqueueTask& _enq_task;
4901
4902 public:
4903 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4904 AbstractGangTask("Enqueue reference objects in parallel"),
4905 _enq_task(enq_task)
4906 { }
4907
4908 virtual void work(uint worker_id) {
4909 _enq_task.work(worker_id);
4910 }
4911 };
4912
4913 // Driver routine for parallel reference enqueueing.
4914 // Creates an instance of the ref enqueueing gang
4915 // task and has the worker threads execute it.
4916
4917 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4918 assert(_workers != NULL, "Need parallel worker threads.");
4919
4920 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4921
4922 _workers->run_task(&enq_task_proxy);
4923 }
4924
4925 // End of weak reference support closures
4926
4927 // Abstract task used to preserve (i.e. copy) any referent objects
4928 // that are in the collection set and are pointed to by reference
4929 // objects discovered by the CM ref processor.
4930
4931 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4932 protected:
4933 G1CollectedHeap* _g1h;
4934 G1ParScanThreadStateSet* _pss;
4935 RefToScanQueueSet* _queues;
4936 ParallelTaskTerminator _terminator;
4937 uint _n_workers;
4938
4939 public:
4940 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4941 AbstractGangTask("ParPreserveCMReferents"),
4942 _g1h(g1h),
4943 _pss(per_thread_states),
4944 _queues(task_queues),
4945 _terminator(workers, _queues),
4946 _n_workers(workers)
4947 { }
4948
4949 void work(uint worker_id) {
4950 ResourceMark rm;
4951 HandleMark hm;
4952
4953 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4954 pss->set_ref_processor(NULL);
4955 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4956
4957 // Is alive closure
4958 G1AlwaysAliveClosure always_alive(_g1h);
4959
4960 // Copying keep alive closure. Applied to referent objects that need
4961 // to be copied.
4962 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4963
4964 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4965
4966 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4967 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4968
4969 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4970 // So this must be true - but assert just in case someone decides to
4971 // change the worker ids.
4972 assert(worker_id < limit, "sanity");
4973 assert(!rp->discovery_is_atomic(), "check this code");
4974
4975 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4976 for (uint idx = worker_id; idx < limit; idx += stride) {
4977 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4978
4979 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4980 while (iter.has_next()) {
4981 // Since discovery is not atomic for the CM ref processor, we
4982 // can see some null referent objects.
4983 iter.load_ptrs(DEBUG_ONLY(true));
4984 oop ref = iter.obj();
4985
4986 // This will filter nulls.
4987 if (iter.is_referent_alive()) {
4988 iter.make_referent_alive();
4989 }
4990 iter.move_to_next();
4991 }
4992 }
4993
4994 // Drain the queue - which may cause stealing
4995 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4996 drain_queue.do_void();
4997 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4998 assert(pss->queue_is_empty(), "should be");
4999 }
5000 };
5001
5002 // Weak Reference processing during an evacuation pause (part 1).
5003 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5004 double ref_proc_start = os::elapsedTime();
5005
5006 ReferenceProcessor* rp = _ref_processor_stw;
5007 assert(rp->discovery_enabled(), "should have been enabled");
5008
5009 // Any reference objects, in the collection set, that were 'discovered'
5010 // by the CM ref processor should have already been copied (either by
5011 // applying the external root copy closure to the discovered lists, or
5012 // by following an RSet entry).
5013 //
5014 // But some of the referents, that are in the collection set, that these
5015 // reference objects point to may not have been copied: the STW ref
5016 // processor would have seen that the reference object had already
5017 // been 'discovered' and would have skipped discovering the reference,
5018 // but would not have treated the reference object as a regular oop.
5019 // As a result the copy closure would not have been applied to the
5020 // referent object.
5021 //
5022 // We need to explicitly copy these referent objects - the references
5023 // will be processed at the end of remarking.
5024 //
5025 // We also need to do this copying before we process the reference
5026 // objects discovered by the STW ref processor in case one of these
5027 // referents points to another object which is also referenced by an
5028 // object discovered by the STW ref processor.
5029
5030 uint no_of_gc_workers = workers()->active_workers();
5031
5032 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5033 per_thread_states,
5034 no_of_gc_workers,
5035 _task_queues);
5036
5037 workers()->run_task(&keep_cm_referents);
5038
5039 // Closure to test whether a referent is alive.
5040 G1STWIsAliveClosure is_alive(this);
5041
5042 // Even when parallel reference processing is enabled, the processing
5043 // of JNI refs is serial and performed serially by the current thread
5044 // rather than by a worker. The following PSS will be used for processing
5045 // JNI refs.
5046
5047 // Use only a single queue for this PSS.
5048 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5049 pss->set_ref_processor(NULL);
5050 assert(pss->queue_is_empty(), "pre-condition");
5051
5052 // Keep alive closure.
5053 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5054
5055 // Serial Complete GC closure
5056 G1STWDrainQueueClosure drain_queue(this, pss);
5057
5058 // Setup the soft refs policy...
5059 rp->setup_policy(false);
5060
5061 ReferenceProcessorStats stats;
5062 if (!rp->processing_is_mt()) {
5063 // Serial reference processing...
5064 stats = rp->process_discovered_references(&is_alive,
5065 &keep_alive,
5066 &drain_queue,
5067 NULL,
5068 _gc_timer_stw);
5069 } else {
5070 // Parallel reference processing
5071 assert(rp->num_q() == no_of_gc_workers, "sanity");
5072 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5073
5074 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5075 stats = rp->process_discovered_references(&is_alive,
5076 &keep_alive,
5077 &drain_queue,
5078 &par_task_executor,
5079 _gc_timer_stw);
5080 }
5081
5082 _gc_tracer_stw->report_gc_reference_stats(stats);
5083
5084 // We have completed copying any necessary live referent objects.
5085 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5086
5087 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5088 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5089 }
5090
5091 // Weak Reference processing during an evacuation pause (part 2).
5092 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5093 double ref_enq_start = os::elapsedTime();
5094
5095 ReferenceProcessor* rp = _ref_processor_stw;
5096 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5097
5098 // Now enqueue any remaining on the discovered lists on to
5099 // the pending list.
5100 if (!rp->processing_is_mt()) {
5101 // Serial reference processing...
5102 rp->enqueue_discovered_references();
5103 } else {
5104 // Parallel reference enqueueing
5105
5106 uint n_workers = workers()->active_workers();
5107
5108 assert(rp->num_q() == n_workers, "sanity");
5109 assert(n_workers <= rp->max_num_q(), "sanity");
5110
5111 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5112 rp->enqueue_discovered_references(&par_task_executor);
5113 }
5114
5115 rp->verify_no_references_recorded();
5116 assert(!rp->discovery_enabled(), "should have been disabled");
5117
5118 // FIXME
5119 // CM's reference processing also cleans up the string and symbol tables.
5120 // Should we do that here also? We could, but it is a serial operation
5121 // and could significantly increase the pause time.
5122
5123 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5124 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5125 }
5126
5127 void G1CollectedHeap::pre_evacuate_collection_set() {
5128 _expand_heap_after_alloc_failure = true;
5129 _evacuation_failed = false;
5130
5131 // Disable the hot card cache.
5132 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5133 hot_card_cache->reset_hot_cache_claimed_index();
5134 hot_card_cache->set_use_cache(false);
5135
5136 }
5137
5138 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5139 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5140
5141 // Should G1EvacuationFailureALot be in effect for this GC?
5142 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5143
5144 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5145 double start_par_time_sec = os::elapsedTime();
5146 double end_par_time_sec;
5147
5148 {
5149 const uint n_workers = workers()->active_workers();
5150 G1RootProcessor root_processor(this, n_workers);
5151 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5152 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5153 if (collector_state()->during_initial_mark_pause()) {
5154 ClassLoaderDataGraph::clear_claimed_marks();
5155 }
5156
5157 // The individual threads will set their evac-failure closures.
5158 if (PrintTerminationStats) {
5159 print_termination_stats_hdr(gclog_or_tty);
5160 }
5161
5162 workers()->run_task(&g1_par_task);
5163 end_par_time_sec = os::elapsedTime();
5164
5165 // Closing the inner scope will execute the destructor
5166 // for the G1RootProcessor object. We record the current
5167 // elapsed time before closing the scope so that time
5168 // taken for the destructor is NOT included in the
5169 // reported parallel time.
5170 }
5171
5172 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5173
5174 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5175 phase_times->record_par_time(par_time_ms);
5176
5177 double code_root_fixup_time_ms =
5178 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5179 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5180
5181 // Process any discovered reference objects - we have
5182 // to do this _before_ we retire the GC alloc regions
5183 // as we may have to copy some 'reachable' referent
5184 // objects (and their reachable sub-graphs) that were
5185 // not copied during the pause.
5186 process_discovered_references(per_thread_states);
5187
5188 if (G1StringDedup::is_enabled()) {
5189 double fixup_start = os::elapsedTime();
5190
5191 G1STWIsAliveClosure is_alive(this);
5192 G1KeepAliveClosure keep_alive(this);
5193 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5194
5195 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5196 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5197 }
5198
5199 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5200
5201 if (evacuation_failed()) {
5202 remove_self_forwarding_pointers();
5203
5204 // Reset the G1EvacuationFailureALot counters and flags
5205 // Note: the values are reset only when an actual
5206 // evacuation failure occurs.
5207 NOT_PRODUCT(reset_evacuation_should_fail();)
5208 }
5209
5210 // Enqueue any remaining references remaining on the STW
5211 // reference processor's discovered lists. We need to do
5212 // this after the card table is cleaned (and verified) as
5213 // the act of enqueueing entries on to the pending list
5214 // will log these updates (and dirty their associated
5215 // cards). We need these updates logged to update any
5216 // RSets.
5217 enqueue_discovered_references(per_thread_states);
5218 }
5219
5220 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5221 _allocator->release_gc_alloc_regions(evacuation_info);
5222
5223 per_thread_states->flush();
5224
5225 record_obj_copy_mem_stats();
5226
5227 _survivor_evac_stats.adjust_desired_plab_sz();
5228 _old_evac_stats.adjust_desired_plab_sz();
5229
5230 // Reset and re-enable the hot card cache.
5231 // Note the counts for the cards in the regions in the
5232 // collection set are reset when the collection set is freed.
5233 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5234 hot_card_cache->reset_hot_cache();
5235 hot_card_cache->set_use_cache(true);
5236
5237 purge_code_root_memory();
5238
5239 redirty_logged_cards();
5240 #if defined(COMPILER2) || INCLUDE_JVMCI
5241 DerivedPointerTable::update_pointers();
5242 #endif
5243 }
5244
5245 void G1CollectedHeap::record_obj_copy_mem_stats() {
5246 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5247 create_g1_evac_summary(&_old_evac_stats));
5248 }
5249
5250 void G1CollectedHeap::free_region(HeapRegion* hr,
5251 FreeRegionList* free_list,
5252 bool par,
5253 bool locked) {
5254 assert(!hr->is_free(), "the region should not be free");
5255 assert(!hr->is_empty(), "the region should not be empty");
5256 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5257 assert(free_list != NULL, "pre-condition");
5258
5259 if (G1VerifyBitmaps) {
5260 MemRegion mr(hr->bottom(), hr->end());
5261 concurrent_mark()->clearRangePrevBitmap(mr);
5262 }
5263
5264 // Clear the card counts for this region.
5265 // Note: we only need to do this if the region is not young
5266 // (since we don't refine cards in young regions).
5267 if (!hr->is_young()) {
5268 _cg1r->hot_card_cache()->reset_card_counts(hr);
5269 }
5270 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5271 free_list->add_ordered(hr);
5272 }
5273
5274 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5275 FreeRegionList* free_list,
5276 bool par) {
5277 assert(hr->is_humongous(), "this is only for humongous regions");
5278 assert(free_list != NULL, "pre-condition");
5279 hr->clear_humongous();
5280 free_region(hr, free_list, par);
5281 }
5282
5283 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5284 const HeapRegionSetCount& humongous_regions_removed) {
5285 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5286 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5287 _old_set.bulk_remove(old_regions_removed);
5288 _humongous_set.bulk_remove(humongous_regions_removed);
5289 }
5290
5291 }
5292
5293 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5294 assert(list != NULL, "list can't be null");
5295 if (!list->is_empty()) {
5296 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5297 _hrm.insert_list_into_free_list(list);
5298 }
5299 }
5300
5301 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5302 decrease_used(bytes);
5303 }
5304
5305 class G1ParCleanupCTTask : public AbstractGangTask {
5306 G1SATBCardTableModRefBS* _ct_bs;
5307 G1CollectedHeap* _g1h;
5308 HeapRegion* volatile _su_head;
5309 public:
5310 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5311 G1CollectedHeap* g1h) :
5312 AbstractGangTask("G1 Par Cleanup CT Task"),
5313 _ct_bs(ct_bs), _g1h(g1h) { }
5314
5315 void work(uint worker_id) {
5316 HeapRegion* r;
5317 while (r = _g1h->pop_dirty_cards_region()) {
5318 clear_cards(r);
5319 }
5320 }
5321
5322 void clear_cards(HeapRegion* r) {
5323 // Cards of the survivors should have already been dirtied.
5324 if (!r->is_survivor()) {
5325 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5326 }
5327 }
5328 };
5329
5330 #ifndef PRODUCT
5331 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5332 G1CollectedHeap* _g1h;
5333 G1SATBCardTableModRefBS* _ct_bs;
5334 public:
5335 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5336 : _g1h(g1h), _ct_bs(ct_bs) { }
5337 virtual bool doHeapRegion(HeapRegion* r) {
5338 if (r->is_survivor()) {
5339 _g1h->verify_dirty_region(r);
5340 } else {
5341 _g1h->verify_not_dirty_region(r);
5342 }
5343 return false;
5344 }
5345 };
5346
5347 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5348 // All of the region should be clean.
5349 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5350 MemRegion mr(hr->bottom(), hr->end());
5351 ct_bs->verify_not_dirty_region(mr);
5352 }
5353
5354 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5355 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5356 // dirty allocated blocks as they allocate them. The thread that
5357 // retires each region and replaces it with a new one will do a
5358 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5359 // not dirty that area (one less thing to have to do while holding
5360 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5361 // is dirty.
5362 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5363 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5364 if (hr->is_young()) {
5365 ct_bs->verify_g1_young_region(mr);
5366 } else {
5367 ct_bs->verify_dirty_region(mr);
5368 }
5369 }
5370
5371 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5372 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5373 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5374 verify_dirty_region(hr);
5375 }
5376 }
5377
5378 void G1CollectedHeap::verify_dirty_young_regions() {
5379 verify_dirty_young_list(_young_list->first_region());
5380 }
5381
5382 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5383 HeapWord* tams, HeapWord* end) {
5384 guarantee(tams <= end,
5385 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5386 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5387 if (result < end) {
5388 gclog_or_tty->cr();
5389 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5390 bitmap_name, p2i(result));
5391 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5392 bitmap_name, p2i(tams), p2i(end));
5393 return false;
5394 }
5395 return true;
5396 }
5397
5398 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5399 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5400 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5401
5402 HeapWord* bottom = hr->bottom();
5403 HeapWord* ptams = hr->prev_top_at_mark_start();
5404 HeapWord* ntams = hr->next_top_at_mark_start();
5405 HeapWord* end = hr->end();
5406
5407 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5408
5409 bool res_n = true;
5410 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5411 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5412 // if we happen to be in that state.
5413 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5414 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5415 }
5416 if (!res_p || !res_n) {
5417 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5418 HR_FORMAT_PARAMS(hr));
5419 gclog_or_tty->print_cr("#### Caller: %s", caller);
5420 return false;
5421 }
5422 return true;
5423 }
5424
5425 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5426 if (!G1VerifyBitmaps) return;
5427
5428 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5429 }
5430
5431 class G1VerifyBitmapClosure : public HeapRegionClosure {
5432 private:
5433 const char* _caller;
5434 G1CollectedHeap* _g1h;
5435 bool _failures;
5436
5437 public:
5438 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5439 _caller(caller), _g1h(g1h), _failures(false) { }
5440
5441 bool failures() { return _failures; }
5442
5443 virtual bool doHeapRegion(HeapRegion* hr) {
5444 bool result = _g1h->verify_bitmaps(_caller, hr);
5445 if (!result) {
5446 _failures = true;
5447 }
5448 return false;
5449 }
5450 };
5451
5452 void G1CollectedHeap::check_bitmaps(const char* caller) {
5453 if (!G1VerifyBitmaps) return;
5454
5455 G1VerifyBitmapClosure cl(caller, this);
5456 heap_region_iterate(&cl);
5457 guarantee(!cl.failures(), "bitmap verification");
5458 }
5459
5460 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5461 private:
5462 bool _failures;
5463 public:
5464 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5465
5466 virtual bool doHeapRegion(HeapRegion* hr) {
5467 uint i = hr->hrm_index();
5468 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5469 if (hr->is_humongous()) {
5470 if (hr->in_collection_set()) {
5471 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5472 _failures = true;
5473 return true;
5474 }
5475 if (cset_state.is_in_cset()) {
5476 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5477 _failures = true;
5478 return true;
5479 }
5480 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5481 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5482 _failures = true;
5483 return true;
5484 }
5485 } else {
5486 if (cset_state.is_humongous()) {
5487 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5488 _failures = true;
5489 return true;
5490 }
5491 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5492 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5493 hr->in_collection_set(), cset_state.value(), i);
5494 _failures = true;
5495 return true;
5496 }
5497 if (cset_state.is_in_cset()) {
5498 if (hr->is_young() != (cset_state.is_young())) {
5499 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5500 hr->is_young(), cset_state.value(), i);
5501 _failures = true;
5502 return true;
5503 }
5504 if (hr->is_old() != (cset_state.is_old())) {
5505 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5506 hr->is_old(), cset_state.value(), i);
5507 _failures = true;
5508 return true;
5509 }
5510 }
5511 }
5512 return false;
5513 }
5514
5515 bool failures() const { return _failures; }
5516 };
5517
5518 bool G1CollectedHeap::check_cset_fast_test() {
5519 G1CheckCSetFastTableClosure cl;
5520 _hrm.iterate(&cl);
5521 return !cl.failures();
5522 }
5523 #endif // PRODUCT
5524
5525 void G1CollectedHeap::cleanUpCardTable() {
5526 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5527 double start = os::elapsedTime();
5528
5529 {
5530 // Iterate over the dirty cards region list.
5531 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5532
5533 workers()->run_task(&cleanup_task);
5534 #ifndef PRODUCT
5535 if (G1VerifyCTCleanup || VerifyAfterGC) {
5536 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5537 heap_region_iterate(&cleanup_verifier);
5538 }
5539 #endif
5540 }
5541
5542 double elapsed = os::elapsedTime() - start;
5543 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5544 }
5545
5546 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5547 size_t pre_used = 0;
5548 FreeRegionList local_free_list("Local List for CSet Freeing");
5549
5550 double young_time_ms = 0.0;
5551 double non_young_time_ms = 0.0;
5552
5553 // Since the collection set is a superset of the the young list,
5554 // all we need to do to clear the young list is clear its
5555 // head and length, and unlink any young regions in the code below
5556 _young_list->clear();
5557
5558 G1CollectorPolicy* policy = g1_policy();
5559
5560 double start_sec = os::elapsedTime();
5561 bool non_young = true;
5562
5563 HeapRegion* cur = cs_head;
5564 int age_bound = -1;
5565 size_t rs_lengths = 0;
5566
5567 while (cur != NULL) {
5568 assert(!is_on_master_free_list(cur), "sanity");
5569 if (non_young) {
5570 if (cur->is_young()) {
5571 double end_sec = os::elapsedTime();
5572 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5573 non_young_time_ms += elapsed_ms;
5574
5575 start_sec = os::elapsedTime();
5576 non_young = false;
5577 }
5578 } else {
5579 if (!cur->is_young()) {
5580 double end_sec = os::elapsedTime();
5581 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5582 young_time_ms += elapsed_ms;
5583
5584 start_sec = os::elapsedTime();
5585 non_young = true;
5586 }
5587 }
5588
5589 rs_lengths += cur->rem_set()->occupied_locked();
5590
5591 HeapRegion* next = cur->next_in_collection_set();
5592 assert(cur->in_collection_set(), "bad CS");
5593 cur->set_next_in_collection_set(NULL);
5594 clear_in_cset(cur);
5595
5596 if (cur->is_young()) {
5597 int index = cur->young_index_in_cset();
5598 assert(index != -1, "invariant");
5599 assert((uint) index < policy->young_cset_region_length(), "invariant");
5600 size_t words_survived = surviving_young_words[index];
5601 cur->record_surv_words_in_group(words_survived);
5602
5603 // At this point the we have 'popped' cur from the collection set
5604 // (linked via next_in_collection_set()) but it is still in the
5605 // young list (linked via next_young_region()). Clear the
5606 // _next_young_region field.
5607 cur->set_next_young_region(NULL);
5608 } else {
5609 int index = cur->young_index_in_cset();
5610 assert(index == -1, "invariant");
5611 }
5612
5613 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5614 (!cur->is_young() && cur->young_index_in_cset() == -1),
5615 "invariant" );
5616
5617 if (!cur->evacuation_failed()) {
5618 MemRegion used_mr = cur->used_region();
5619
5620 // And the region is empty.
5621 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5622 pre_used += cur->used();
5623 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5624 } else {
5625 cur->uninstall_surv_rate_group();
5626 if (cur->is_young()) {
5627 cur->set_young_index_in_cset(-1);
5628 }
5629 cur->set_evacuation_failed(false);
5630 // The region is now considered to be old.
5631 cur->set_old();
5632 // Do some allocation statistics accounting. Regions that failed evacuation
5633 // are always made old, so there is no need to update anything in the young
5634 // gen statistics, but we need to update old gen statistics.
5635 size_t used_words = cur->marked_bytes() / HeapWordSize;
5636 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5637 _old_set.add(cur);
5638 evacuation_info.increment_collectionset_used_after(cur->used());
5639 }
5640 cur = next;
5641 }
5642
5643 evacuation_info.set_regions_freed(local_free_list.length());
5644 policy->record_max_rs_lengths(rs_lengths);
5645 policy->cset_regions_freed();
5646
5647 double end_sec = os::elapsedTime();
5648 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5649
5650 if (non_young) {
5651 non_young_time_ms += elapsed_ms;
5652 } else {
5653 young_time_ms += elapsed_ms;
5654 }
5655
5656 prepend_to_freelist(&local_free_list);
5657 decrement_summary_bytes(pre_used);
5658 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5659 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5660 }
5661
5662 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5663 private:
5664 FreeRegionList* _free_region_list;
5665 HeapRegionSet* _proxy_set;
5666 HeapRegionSetCount _humongous_regions_removed;
5667 size_t _freed_bytes;
5668 public:
5669
5670 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5671 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5672 }
5673
5674 virtual bool doHeapRegion(HeapRegion* r) {
5675 if (!r->is_starts_humongous()) {
5676 return false;
5677 }
5678
5679 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5680
5681 oop obj = (oop)r->bottom();
5682 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5683
5684 // The following checks whether the humongous object is live are sufficient.
5685 // The main additional check (in addition to having a reference from the roots
5686 // or the young gen) is whether the humongous object has a remembered set entry.
5687 //
5688 // A humongous object cannot be live if there is no remembered set for it
5689 // because:
5690 // - there can be no references from within humongous starts regions referencing
5691 // the object because we never allocate other objects into them.
5692 // (I.e. there are no intra-region references that may be missed by the
5693 // remembered set)
5694 // - as soon there is a remembered set entry to the humongous starts region
5695 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5696 // until the end of a concurrent mark.
5697 //
5698 // It is not required to check whether the object has been found dead by marking
5699 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5700 // all objects allocated during that time are considered live.
5701 // SATB marking is even more conservative than the remembered set.
5702 // So if at this point in the collection there is no remembered set entry,
5703 // nobody has a reference to it.
5704 // At the start of collection we flush all refinement logs, and remembered sets
5705 // are completely up-to-date wrt to references to the humongous object.
5706 //
5707 // Other implementation considerations:
5708 // - never consider object arrays at this time because they would pose
5709 // considerable effort for cleaning up the the remembered sets. This is
5710 // required because stale remembered sets might reference locations that
5711 // are currently allocated into.
5712 uint region_idx = r->hrm_index();
5713 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5714 !r->rem_set()->is_empty()) {
5715
5716 if (G1TraceEagerReclaimHumongousObjects) {
5717 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",
5718 region_idx,
5719 (size_t)obj->size() * HeapWordSize,
5720 p2i(r->bottom()),
5721 r->rem_set()->occupied(),
5722 r->rem_set()->strong_code_roots_list_length(),
5723 next_bitmap->isMarked(r->bottom()),
5724 g1h->is_humongous_reclaim_candidate(region_idx),
5725 obj->is_typeArray()
5726 );
5727 }
5728
5729 return false;
5730 }
5731
5732 guarantee(obj->is_typeArray(),
5733 "Only eagerly reclaiming type arrays is supported, but the object "
5734 PTR_FORMAT " is not.", p2i(r->bottom()));
5735
5736 if (G1TraceEagerReclaimHumongousObjects) {
5737 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",
5738 region_idx,
5739 (size_t)obj->size() * HeapWordSize,
5740 p2i(r->bottom()),
5741 r->rem_set()->occupied(),
5742 r->rem_set()->strong_code_roots_list_length(),
5743 next_bitmap->isMarked(r->bottom()),
5744 g1h->is_humongous_reclaim_candidate(region_idx),
5745 obj->is_typeArray()
5746 );
5747 }
5748 // Need to clear mark bit of the humongous object if already set.
5749 if (next_bitmap->isMarked(r->bottom())) {
5750 next_bitmap->clear(r->bottom());
5751 }
5752 do {
5753 HeapRegion* next = g1h->next_region_in_humongous(r);
5754 _freed_bytes += r->used();
5755 r->set_containing_set(NULL);
5756 _humongous_regions_removed.increment(1u, r->capacity());
5757 g1h->free_humongous_region(r, _free_region_list, false);
5758 r = next;
5759 } while (r != NULL);
5760
5761 return false;
5762 }
5763
5764 HeapRegionSetCount& humongous_free_count() {
5765 return _humongous_regions_removed;
5766 }
5767
5768 size_t bytes_freed() const {
5769 return _freed_bytes;
5770 }
5771
5772 size_t humongous_reclaimed() const {
5773 return _humongous_regions_removed.length();
5774 }
5775 };
5776
5777 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5778 assert_at_safepoint(true);
5779
5780 if (!G1EagerReclaimHumongousObjects ||
5781 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5782 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5783 return;
5784 }
5785
5786 double start_time = os::elapsedTime();
5787
5788 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5789
5790 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5791 heap_region_iterate(&cl);
5792
5793 HeapRegionSetCount empty_set;
5794 remove_from_old_sets(empty_set, cl.humongous_free_count());
5795
5796 G1HRPrinter* hrp = hr_printer();
5797 if (hrp->is_active()) {
5798 FreeRegionListIterator iter(&local_cleanup_list);
5799 while (iter.more_available()) {
5800 HeapRegion* hr = iter.get_next();
5801 hrp->cleanup(hr);
5802 }
5803 }
5804
5805 prepend_to_freelist(&local_cleanup_list);
5806 decrement_summary_bytes(cl.bytes_freed());
5807
5808 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5809 cl.humongous_reclaimed());
5810 }
5811
5812 // This routine is similar to the above but does not record
5813 // any policy statistics or update free lists; we are abandoning
5814 // the current incremental collection set in preparation of a
5815 // full collection. After the full GC we will start to build up
5816 // the incremental collection set again.
5817 // This is only called when we're doing a full collection
5818 // and is immediately followed by the tearing down of the young list.
5819
5820 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5821 HeapRegion* cur = cs_head;
5822
5823 while (cur != NULL) {
5824 HeapRegion* next = cur->next_in_collection_set();
5825 assert(cur->in_collection_set(), "bad CS");
5826 cur->set_next_in_collection_set(NULL);
5827 clear_in_cset(cur);
5828 cur->set_young_index_in_cset(-1);
5829 cur = next;
5830 }
5831 }
5832
5833 void G1CollectedHeap::set_free_regions_coming() {
5834 if (G1ConcRegionFreeingVerbose) {
5835 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5836 "setting free regions coming");
5837 }
5838
5839 assert(!free_regions_coming(), "pre-condition");
5840 _free_regions_coming = true;
5841 }
5842
5843 void G1CollectedHeap::reset_free_regions_coming() {
5844 assert(free_regions_coming(), "pre-condition");
5845
5846 {
5847 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5848 _free_regions_coming = false;
5849 SecondaryFreeList_lock->notify_all();
5850 }
5851
5852 if (G1ConcRegionFreeingVerbose) {
5853 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5854 "reset free regions coming");
5855 }
5856 }
5857
5858 void G1CollectedHeap::wait_while_free_regions_coming() {
5859 // Most of the time we won't have to wait, so let's do a quick test
5860 // first before we take the lock.
5861 if (!free_regions_coming()) {
5862 return;
5863 }
5864
5865 if (G1ConcRegionFreeingVerbose) {
5866 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5867 "waiting for free regions");
5868 }
5869
5870 {
5871 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5872 while (free_regions_coming()) {
5873 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5874 }
5875 }
5876
5877 if (G1ConcRegionFreeingVerbose) {
5878 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5879 "done waiting for free regions");
5880 }
5881 }
5882
5883 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5884 return _allocator->is_retained_old_region(hr);
5885 }
5886
5887 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5888 _young_list->push_region(hr);
5889 }
5890
5891 class NoYoungRegionsClosure: public HeapRegionClosure {
5892 private:
5893 bool _success;
5894 public:
5895 NoYoungRegionsClosure() : _success(true) { }
5896 bool doHeapRegion(HeapRegion* r) {
5897 if (r->is_young()) {
5898 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5899 p2i(r->bottom()), p2i(r->end()));
5900 _success = false;
5901 }
5902 return false;
5903 }
5904 bool success() { return _success; }
5905 };
5906
5907 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5908 bool ret = _young_list->check_list_empty(check_sample);
5909
5910 if (check_heap) {
5911 NoYoungRegionsClosure closure;
5912 heap_region_iterate(&closure);
5913 ret = ret && closure.success();
5914 }
5915
5916 return ret;
5917 }
5918
5919 class TearDownRegionSetsClosure : public HeapRegionClosure {
5920 private:
5921 HeapRegionSet *_old_set;
5922
5923 public:
5924 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5925
5926 bool doHeapRegion(HeapRegion* r) {
5927 if (r->is_old()) {
5928 _old_set->remove(r);
5929 } else {
5930 // We ignore free regions, we'll empty the free list afterwards.
5931 // We ignore young regions, we'll empty the young list afterwards.
5932 // We ignore humongous regions, we're not tearing down the
5933 // humongous regions set.
5934 assert(r->is_free() || r->is_young() || r->is_humongous(),
5935 "it cannot be another type");
5936 }
5937 return false;
5938 }
5939
5940 ~TearDownRegionSetsClosure() {
5941 assert(_old_set->is_empty(), "post-condition");
5942 }
5943 };
5944
5945 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5946 assert_at_safepoint(true /* should_be_vm_thread */);
5947
5948 if (!free_list_only) {
5949 TearDownRegionSetsClosure cl(&_old_set);
5950 heap_region_iterate(&cl);
5951
5952 // Note that emptying the _young_list is postponed and instead done as
5953 // the first step when rebuilding the regions sets again. The reason for
5954 // this is that during a full GC string deduplication needs to know if
5955 // a collected region was young or old when the full GC was initiated.
5956 }
5957 _hrm.remove_all_free_regions();
5958 }
5959
5960 void G1CollectedHeap::increase_used(size_t bytes) {
5961 _summary_bytes_used += bytes;
5962 }
5963
5964 void G1CollectedHeap::decrease_used(size_t bytes) {
5965 assert(_summary_bytes_used >= bytes,
5966 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5967 _summary_bytes_used, bytes);
5968 _summary_bytes_used -= bytes;
5969 }
5970
5971 void G1CollectedHeap::set_used(size_t bytes) {
5972 _summary_bytes_used = bytes;
5973 }
5974
5975 class RebuildRegionSetsClosure : public HeapRegionClosure {
5976 private:
5977 bool _free_list_only;
5978 HeapRegionSet* _old_set;
5979 HeapRegionManager* _hrm;
5980 size_t _total_used;
5981
5982 public:
5983 RebuildRegionSetsClosure(bool free_list_only,
5984 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5985 _free_list_only(free_list_only),
5986 _old_set(old_set), _hrm(hrm), _total_used(0) {
5987 assert(_hrm->num_free_regions() == 0, "pre-condition");
5988 if (!free_list_only) {
5989 assert(_old_set->is_empty(), "pre-condition");
5990 }
5991 }
5992
5993 bool doHeapRegion(HeapRegion* r) {
5994 if (r->is_empty()) {
5995 // Add free regions to the free list
5996 r->set_free();
5997 r->set_allocation_context(AllocationContext::system());
5998 _hrm->insert_into_free_list(r);
5999 } else if (!_free_list_only) {
6000 assert(!r->is_young(), "we should not come across young regions");
6001
6002 if (r->is_humongous()) {
6003 // We ignore humongous regions. We left the humongous set unchanged.
6004 } else {
6005 // Objects that were compacted would have ended up on regions
6006 // that were previously old or free. Archive regions (which are
6007 // old) will not have been touched.
6008 assert(r->is_free() || r->is_old(), "invariant");
6009 // We now consider them old, so register as such. Leave
6010 // archive regions set that way, however, while still adding
6011 // them to the old set.
6012 if (!r->is_archive()) {
6013 r->set_old();
6014 }
6015 _old_set->add(r);
6016 }
6017 _total_used += r->used();
6018 }
6019
6020 return false;
6021 }
6022
6023 size_t total_used() {
6024 return _total_used;
6025 }
6026 };
6027
6028 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6029 assert_at_safepoint(true /* should_be_vm_thread */);
6030
6031 if (!free_list_only) {
6032 _young_list->empty_list();
6033 }
6034
6035 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6036 heap_region_iterate(&cl);
6037
6038 if (!free_list_only) {
6039 set_used(cl.total_used());
6040 if (_archive_allocator != NULL) {
6041 _archive_allocator->clear_used();
6042 }
6043 }
6044 assert(used_unlocked() == recalculate_used(),
6045 "inconsistent used_unlocked(), "
6046 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6047 used_unlocked(), recalculate_used());
6048 }
6049
6050 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6051 _refine_cte_cl->set_concurrent(concurrent);
6052 }
6053
6054 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6055 HeapRegion* hr = heap_region_containing(p);
6056 return hr->is_in(p);
6057 }
6058
6059 // Methods for the mutator alloc region
6060
6061 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6062 bool force) {
6063 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6064 assert(!force || g1_policy()->can_expand_young_list(),
6065 "if force is true we should be able to expand the young list");
6066 bool young_list_full = g1_policy()->is_young_list_full();
6067 if (force || !young_list_full) {
6068 HeapRegion* new_alloc_region = new_region(word_size,
6069 false /* is_old */,
6070 false /* do_expand */);
6071 if (new_alloc_region != NULL) {
6072 set_region_short_lived_locked(new_alloc_region);
6073 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6074 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6075 return new_alloc_region;
6076 }
6077 }
6078 return NULL;
6079 }
6080
6081 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6082 size_t allocated_bytes) {
6083 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6084 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6085
6086 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6087 increase_used(allocated_bytes);
6088 _hr_printer.retire(alloc_region);
6089 // We update the eden sizes here, when the region is retired,
6090 // instead of when it's allocated, since this is the point that its
6091 // used space has been recored in _summary_bytes_used.
6092 g1mm()->update_eden_size();
6093 }
6094
6095 // Methods for the GC alloc regions
6096
6097 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6098 uint count,
6099 InCSetState dest) {
6100 assert(FreeList_lock->owned_by_self(), "pre-condition");
6101
6102 if (count < g1_policy()->max_regions(dest)) {
6103 const bool is_survivor = (dest.is_young());
6104 HeapRegion* new_alloc_region = new_region(word_size,
6105 !is_survivor,
6106 true /* do_expand */);
6107 if (new_alloc_region != NULL) {
6108 // We really only need to do this for old regions given that we
6109 // should never scan survivors. But it doesn't hurt to do it
6110 // for survivors too.
6111 new_alloc_region->record_timestamp();
6112 if (is_survivor) {
6113 new_alloc_region->set_survivor();
6114 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6115 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6116 } else {
6117 new_alloc_region->set_old();
6118 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6119 check_bitmaps("Old Region Allocation", new_alloc_region);
6120 }
6121 bool during_im = collector_state()->during_initial_mark_pause();
6122 new_alloc_region->note_start_of_copying(during_im);
6123 return new_alloc_region;
6124 }
6125 }
6126 return NULL;
6127 }
6128
6129 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6130 size_t allocated_bytes,
6131 InCSetState dest) {
6132 bool during_im = collector_state()->during_initial_mark_pause();
6133 alloc_region->note_end_of_copying(during_im);
6134 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6135 if (dest.is_young()) {
6136 young_list()->add_survivor_region(alloc_region);
6137 } else {
6138 _old_set.add(alloc_region);
6139 }
6140 _hr_printer.retire(alloc_region);
6141 }
6142
6143 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6144 bool expanded = false;
6145 uint index = _hrm.find_highest_free(&expanded);
6146
6147 if (index != G1_NO_HRM_INDEX) {
6148 if (expanded) {
6149 ergo_verbose1(ErgoHeapSizing,
6150 "attempt heap expansion",
6151 ergo_format_reason("requested address range outside heap bounds")
6152 ergo_format_byte("region size"),
6153 HeapRegion::GrainWords * HeapWordSize);
6154 }
6155 _hrm.allocate_free_regions_starting_at(index, 1);
6156 return region_at(index);
6157 }
6158 return NULL;
6159 }
6160
6161 // Heap region set verification
6162
6163 class VerifyRegionListsClosure : public HeapRegionClosure {
6164 private:
6165 HeapRegionSet* _old_set;
6166 HeapRegionSet* _humongous_set;
6167 HeapRegionManager* _hrm;
6168
6169 public:
6170 HeapRegionSetCount _old_count;
6171 HeapRegionSetCount _humongous_count;
6172 HeapRegionSetCount _free_count;
6173
6174 VerifyRegionListsClosure(HeapRegionSet* old_set,
6175 HeapRegionSet* humongous_set,
6176 HeapRegionManager* hrm) :
6177 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6178 _old_count(), _humongous_count(), _free_count(){ }
6179
6180 bool doHeapRegion(HeapRegion* hr) {
6181 if (hr->is_young()) {
6182 // TODO
6183 } else if (hr->is_humongous()) {
6184 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6185 _humongous_count.increment(1u, hr->capacity());
6186 } else if (hr->is_empty()) {
6187 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6188 _free_count.increment(1u, hr->capacity());
6189 } else if (hr->is_old()) {
6190 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6191 _old_count.increment(1u, hr->capacity());
6192 } else {
6193 // There are no other valid region types. Check for one invalid
6194 // one we can identify: pinned without old or humongous set.
6195 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6196 ShouldNotReachHere();
6197 }
6198 return false;
6199 }
6200
6201 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6202 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6203 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6204 old_set->total_capacity_bytes(), _old_count.capacity());
6205
6206 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6207 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6208 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6209
6210 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());
6211 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6212 free_list->total_capacity_bytes(), _free_count.capacity());
6213 }
6214 };
6215
6216 void G1CollectedHeap::verify_region_sets() {
6217 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6218
6219 // First, check the explicit lists.
6220 _hrm.verify();
6221 {
6222 // Given that a concurrent operation might be adding regions to
6223 // the secondary free list we have to take the lock before
6224 // verifying it.
6225 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6226 _secondary_free_list.verify_list();
6227 }
6228
6229 // If a concurrent region freeing operation is in progress it will
6230 // be difficult to correctly attributed any free regions we come
6231 // across to the correct free list given that they might belong to
6232 // one of several (free_list, secondary_free_list, any local lists,
6233 // etc.). So, if that's the case we will skip the rest of the
6234 // verification operation. Alternatively, waiting for the concurrent
6235 // operation to complete will have a non-trivial effect on the GC's
6236 // operation (no concurrent operation will last longer than the
6237 // interval between two calls to verification) and it might hide
6238 // any issues that we would like to catch during testing.
6239 if (free_regions_coming()) {
6240 return;
6241 }
6242
6243 // Make sure we append the secondary_free_list on the free_list so
6244 // that all free regions we will come across can be safely
6245 // attributed to the free_list.
6246 append_secondary_free_list_if_not_empty_with_lock();
6247
6248 // Finally, make sure that the region accounting in the lists is
6249 // consistent with what we see in the heap.
6250
6251 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6252 heap_region_iterate(&cl);
6253 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6254 }
6255
6256 // Optimized nmethod scanning
6257
6258 class RegisterNMethodOopClosure: public OopClosure {
6259 G1CollectedHeap* _g1h;
6260 nmethod* _nm;
6261
6262 template <class T> void do_oop_work(T* p) {
6263 T heap_oop = oopDesc::load_heap_oop(p);
6264 if (!oopDesc::is_null(heap_oop)) {
6265 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6266 HeapRegion* hr = _g1h->heap_region_containing(obj);
6267 assert(!hr->is_continues_humongous(),
6268 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6269 " starting at " HR_FORMAT,
6270 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6271
6272 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6273 hr->add_strong_code_root_locked(_nm);
6274 }
6275 }
6276
6277 public:
6278 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6279 _g1h(g1h), _nm(nm) {}
6280
6281 void do_oop(oop* p) { do_oop_work(p); }
6282 void do_oop(narrowOop* p) { do_oop_work(p); }
6283 };
6284
6285 class UnregisterNMethodOopClosure: public OopClosure {
6286 G1CollectedHeap* _g1h;
6287 nmethod* _nm;
6288
6289 template <class T> void do_oop_work(T* p) {
6290 T heap_oop = oopDesc::load_heap_oop(p);
6291 if (!oopDesc::is_null(heap_oop)) {
6292 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6293 HeapRegion* hr = _g1h->heap_region_containing(obj);
6294 assert(!hr->is_continues_humongous(),
6295 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6296 " starting at " HR_FORMAT,
6297 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6298
6299 hr->remove_strong_code_root(_nm);
6300 }
6301 }
6302
6303 public:
6304 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6305 _g1h(g1h), _nm(nm) {}
6306
6307 void do_oop(oop* p) { do_oop_work(p); }
6308 void do_oop(narrowOop* p) { do_oop_work(p); }
6309 };
6310
6311 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6312 CollectedHeap::register_nmethod(nm);
6313
6314 guarantee(nm != NULL, "sanity");
6315 RegisterNMethodOopClosure reg_cl(this, nm);
6316 nm->oops_do(®_cl);
6317 }
6318
6319 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6320 CollectedHeap::unregister_nmethod(nm);
6321
6322 guarantee(nm != NULL, "sanity");
6323 UnregisterNMethodOopClosure reg_cl(this, nm);
6324 nm->oops_do(®_cl, true);
6325 }
6326
6327 void G1CollectedHeap::purge_code_root_memory() {
6328 double purge_start = os::elapsedTime();
6329 G1CodeRootSet::purge();
6330 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6331 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6332 }
6333
6334 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6335 G1CollectedHeap* _g1h;
6336
6337 public:
6338 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6339 _g1h(g1h) {}
6340
6341 void do_code_blob(CodeBlob* cb) {
6342 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6343 if (nm == NULL) {
6344 return;
6345 }
6346
6347 if (ScavengeRootsInCode) {
6348 _g1h->register_nmethod(nm);
6349 }
6350 }
6351 };
6352
6353 void G1CollectedHeap::rebuild_strong_code_roots() {
6354 RebuildStrongCodeRootClosure blob_cl(this);
6355 CodeCache::blobs_do(&blob_cl);
6356 }