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::user_requested_concurrent_full_gc(GCCause::Cause cause) {
2263 switch (cause) {
2264 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2265 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2266 case GCCause::_update_allocation_context_stats_inc: return true;
2267 case GCCause::_wb_conc_mark: return true;
2268 default : return false;
2269 }
2270 }
2271
2272 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2273 switch (cause) {
2274 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2275 case GCCause::_g1_humongous_allocation: return true;
2276 default: return user_requested_concurrent_full_gc(cause);
2277 }
2278 }
2279
2280 #ifndef PRODUCT
2281 void G1CollectedHeap::allocate_dummy_regions() {
2282 // Let's fill up most of the region
2283 size_t word_size = HeapRegion::GrainWords - 1024;
2284 // And as a result the region we'll allocate will be humongous.
2285 guarantee(is_humongous(word_size), "sanity");
2286
2287 // _filler_array_max_size is set to humongous object threshold
2288 // but temporarily change it to use CollectedHeap::fill_with_object().
2289 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2290
2291 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2292 // Let's use the existing mechanism for the allocation
2293 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2294 AllocationContext::system());
2295 if (dummy_obj != NULL) {
2296 MemRegion mr(dummy_obj, word_size);
2297 CollectedHeap::fill_with_object(mr);
2298 } else {
2299 // If we can't allocate once, we probably cannot allocate
2300 // again. Let's get out of the loop.
2301 break;
2302 }
2303 }
2304 }
2305 #endif // !PRODUCT
2306
2307 void G1CollectedHeap::increment_old_marking_cycles_started() {
2308 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2309 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2310 "Wrong marking cycle count (started: %d, completed: %d)",
2311 _old_marking_cycles_started, _old_marking_cycles_completed);
2312
2313 _old_marking_cycles_started++;
2314 }
2315
2316 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2317 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2318
2319 // We assume that if concurrent == true, then the caller is a
2320 // concurrent thread that was joined the Suspendible Thread
2321 // Set. If there's ever a cheap way to check this, we should add an
2322 // assert here.
2323
2324 // Given that this method is called at the end of a Full GC or of a
2325 // concurrent cycle, and those can be nested (i.e., a Full GC can
2326 // interrupt a concurrent cycle), the number of full collections
2327 // completed should be either one (in the case where there was no
2328 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2329 // behind the number of full collections started.
2330
2331 // This is the case for the inner caller, i.e. a Full GC.
2332 assert(concurrent ||
2333 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2334 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2335 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2336 "is inconsistent with _old_marking_cycles_completed = %u",
2337 _old_marking_cycles_started, _old_marking_cycles_completed);
2338
2339 // This is the case for the outer caller, i.e. the concurrent cycle.
2340 assert(!concurrent ||
2341 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2342 "for outer caller (concurrent cycle): "
2343 "_old_marking_cycles_started = %u "
2344 "is inconsistent with _old_marking_cycles_completed = %u",
2345 _old_marking_cycles_started, _old_marking_cycles_completed);
2346
2347 _old_marking_cycles_completed += 1;
2348
2349 // We need to clear the "in_progress" flag in the CM thread before
2350 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2351 // is set) so that if a waiter requests another System.gc() it doesn't
2352 // incorrectly see that a marking cycle is still in progress.
2353 if (concurrent) {
2354 _cmThread->set_idle();
2355 }
2356
2357 // This notify_all() will ensure that a thread that called
2358 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2359 // and it's waiting for a full GC to finish will be woken up. It is
2360 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2361 FullGCCount_lock->notify_all();
2362 }
2363
2364 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2365 GCIdMarkAndRestore conc_gc_id_mark;
2366 collector_state()->set_concurrent_cycle_started(true);
2367 _gc_timer_cm->register_gc_start(start_time);
2368
2369 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2370 trace_heap_before_gc(_gc_tracer_cm);
2371 _cmThread->set_gc_id(GCId::current());
2372 }
2373
2374 void G1CollectedHeap::register_concurrent_cycle_end() {
2375 if (collector_state()->concurrent_cycle_started()) {
2376 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2377 if (_cm->has_aborted()) {
2378 _gc_tracer_cm->report_concurrent_mode_failure();
2379 }
2380
2381 _gc_timer_cm->register_gc_end();
2382 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2383
2384 // Clear state variables to prepare for the next concurrent cycle.
2385 collector_state()->set_concurrent_cycle_started(false);
2386 _heap_summary_sent = false;
2387 }
2388 }
2389
2390 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2391 if (collector_state()->concurrent_cycle_started()) {
2392 // This function can be called when:
2393 // the cleanup pause is run
2394 // the concurrent cycle is aborted before the cleanup pause.
2395 // the concurrent cycle is aborted after the cleanup pause,
2396 // but before the concurrent cycle end has been registered.
2397 // Make sure that we only send the heap information once.
2398 if (!_heap_summary_sent) {
2399 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2400 trace_heap_after_gc(_gc_tracer_cm);
2401 _heap_summary_sent = true;
2402 }
2403 }
2404 }
2405
2406 void G1CollectedHeap::collect(GCCause::Cause cause) {
2407 assert_heap_not_locked();
2408
2409 uint gc_count_before;
2410 uint old_marking_count_before;
2411 uint full_gc_count_before;
2412 bool retry_gc;
2413
2414 do {
2415 retry_gc = false;
2416
2417 {
2418 MutexLocker ml(Heap_lock);
2419
2420 // Read the GC count while holding the Heap_lock
2421 gc_count_before = total_collections();
2422 full_gc_count_before = total_full_collections();
2423 old_marking_count_before = _old_marking_cycles_started;
2424 }
2425
2426 if (should_do_concurrent_full_gc(cause)) {
2427 // Schedule an initial-mark evacuation pause that will start a
2428 // concurrent cycle. We're setting word_size to 0 which means that
2429 // we are not requesting a post-GC allocation.
2430 VM_G1IncCollectionPause op(gc_count_before,
2431 0, /* word_size */
2432 true, /* should_initiate_conc_mark */
2433 g1_policy()->max_pause_time_ms(),
2434 cause);
2435 op.set_allocation_context(AllocationContext::current());
2436
2437 VMThread::execute(&op);
2438 if (!op.pause_succeeded()) {
2439 if (old_marking_count_before == _old_marking_cycles_started) {
2440 retry_gc = op.should_retry_gc();
2441 } else {
2442 // A Full GC happened while we were trying to schedule the
2443 // initial-mark GC. No point in starting a new cycle given
2444 // that the whole heap was collected anyway.
2445 }
2446
2447 if (retry_gc) {
2448 if (GC_locker::is_active_and_needs_gc()) {
2449 GC_locker::stall_until_clear();
2450 }
2451 }
2452 }
2453 } else {
2454 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2455 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2456
2457 // Schedule a standard evacuation pause. We're setting word_size
2458 // to 0 which means that we are not requesting a post-GC allocation.
2459 VM_G1IncCollectionPause op(gc_count_before,
2460 0, /* word_size */
2461 false, /* should_initiate_conc_mark */
2462 g1_policy()->max_pause_time_ms(),
2463 cause);
2464 VMThread::execute(&op);
2465 } else {
2466 // Schedule a Full GC.
2467 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2468 VMThread::execute(&op);
2469 }
2470 }
2471 } while (retry_gc);
2472 }
2473
2474 bool G1CollectedHeap::is_in(const void* p) const {
2475 if (_hrm.reserved().contains(p)) {
2476 // Given that we know that p is in the reserved space,
2477 // heap_region_containing() should successfully
2478 // return the containing region.
2479 HeapRegion* hr = heap_region_containing(p);
2480 return hr->is_in(p);
2481 } else {
2482 return false;
2483 }
2484 }
2485
2486 #ifdef ASSERT
2487 bool G1CollectedHeap::is_in_exact(const void* p) const {
2488 bool contains = reserved_region().contains(p);
2489 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2490 if (contains && available) {
2491 return true;
2492 } else {
2493 return false;
2494 }
2495 }
2496 #endif
2497
2498 bool G1CollectedHeap::obj_in_cs(oop obj) {
2499 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2500 return r != NULL && r->in_collection_set();
2501 }
2502
2503 // Iteration functions.
2504
2505 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2506
2507 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2508 ExtendedOopClosure* _cl;
2509 public:
2510 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2511 bool doHeapRegion(HeapRegion* r) {
2512 if (!r->is_continues_humongous()) {
2513 r->oop_iterate(_cl);
2514 }
2515 return false;
2516 }
2517 };
2518
2519 // Iterates an ObjectClosure over all objects within a HeapRegion.
2520
2521 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2522 ObjectClosure* _cl;
2523 public:
2524 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2525 bool doHeapRegion(HeapRegion* r) {
2526 if (!r->is_continues_humongous()) {
2527 r->object_iterate(_cl);
2528 }
2529 return false;
2530 }
2531 };
2532
2533 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2534 IterateObjectClosureRegionClosure blk(cl);
2535 heap_region_iterate(&blk);
2536 }
2537
2538 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2539 _hrm.iterate(cl);
2540 }
2541
2542 void
2543 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2544 uint worker_id,
2545 HeapRegionClaimer *hrclaimer,
2546 bool concurrent) const {
2547 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2548 }
2549
2550 // Clear the cached CSet starting regions and (more importantly)
2551 // the time stamps. Called when we reset the GC time stamp.
2552 void G1CollectedHeap::clear_cset_start_regions() {
2553 assert(_worker_cset_start_region != NULL, "sanity");
2554 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2555
2556 for (uint i = 0; i < ParallelGCThreads; i++) {
2557 _worker_cset_start_region[i] = NULL;
2558 _worker_cset_start_region_time_stamp[i] = 0;
2559 }
2560 }
2561
2562 // Given the id of a worker, obtain or calculate a suitable
2563 // starting region for iterating over the current collection set.
2564 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2565 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2566
2567 HeapRegion* result = NULL;
2568 unsigned gc_time_stamp = get_gc_time_stamp();
2569
2570 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2571 // Cached starting region for current worker was set
2572 // during the current pause - so it's valid.
2573 // Note: the cached starting heap region may be NULL
2574 // (when the collection set is empty).
2575 result = _worker_cset_start_region[worker_i];
2576 assert(result == NULL || result->in_collection_set(), "sanity");
2577 return result;
2578 }
2579
2580 // The cached entry was not valid so let's calculate
2581 // a suitable starting heap region for this worker.
2582
2583 // We want the parallel threads to start their collection
2584 // set iteration at different collection set regions to
2585 // avoid contention.
2586 // If we have:
2587 // n collection set regions
2588 // p threads
2589 // Then thread t will start at region floor ((t * n) / p)
2590
2591 result = g1_policy()->collection_set();
2592 uint cs_size = g1_policy()->cset_region_length();
2593 uint active_workers = workers()->active_workers();
2594
2595 uint end_ind = (cs_size * worker_i) / active_workers;
2596 uint start_ind = 0;
2597
2598 if (worker_i > 0 &&
2599 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2600 // Previous workers starting region is valid
2601 // so let's iterate from there
2602 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2603 result = _worker_cset_start_region[worker_i - 1];
2604 }
2605
2606 for (uint i = start_ind; i < end_ind; i++) {
2607 result = result->next_in_collection_set();
2608 }
2609
2610 // Note: the calculated starting heap region may be NULL
2611 // (when the collection set is empty).
2612 assert(result == NULL || result->in_collection_set(), "sanity");
2613 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2614 "should be updated only once per pause");
2615 _worker_cset_start_region[worker_i] = result;
2616 OrderAccess::storestore();
2617 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2618 return result;
2619 }
2620
2621 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2622 HeapRegion* r = g1_policy()->collection_set();
2623 while (r != NULL) {
2624 HeapRegion* next = r->next_in_collection_set();
2625 if (cl->doHeapRegion(r)) {
2626 cl->incomplete();
2627 return;
2628 }
2629 r = next;
2630 }
2631 }
2632
2633 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2634 HeapRegionClosure *cl) {
2635 if (r == NULL) {
2636 // The CSet is empty so there's nothing to do.
2637 return;
2638 }
2639
2640 assert(r->in_collection_set(),
2641 "Start region must be a member of the collection set.");
2642 HeapRegion* cur = r;
2643 while (cur != NULL) {
2644 HeapRegion* next = cur->next_in_collection_set();
2645 if (cl->doHeapRegion(cur) && false) {
2646 cl->incomplete();
2647 return;
2648 }
2649 cur = next;
2650 }
2651 cur = g1_policy()->collection_set();
2652 while (cur != r) {
2653 HeapRegion* next = cur->next_in_collection_set();
2654 if (cl->doHeapRegion(cur) && false) {
2655 cl->incomplete();
2656 return;
2657 }
2658 cur = next;
2659 }
2660 }
2661
2662 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2663 HeapRegion* result = _hrm.next_region_in_heap(from);
2664 while (result != NULL && result->is_pinned()) {
2665 result = _hrm.next_region_in_heap(result);
2666 }
2667 return result;
2668 }
2669
2670 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2671 HeapRegion* hr = heap_region_containing(addr);
2672 return hr->block_start(addr);
2673 }
2674
2675 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2676 HeapRegion* hr = heap_region_containing(addr);
2677 return hr->block_size(addr);
2678 }
2679
2680 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2681 HeapRegion* hr = heap_region_containing(addr);
2682 return hr->block_is_obj(addr);
2683 }
2684
2685 bool G1CollectedHeap::supports_tlab_allocation() const {
2686 return true;
2687 }
2688
2689 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2690 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2691 }
2692
2693 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2694 return young_list()->eden_used_bytes();
2695 }
2696
2697 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2698 // must be equal to the humongous object limit.
2699 size_t G1CollectedHeap::max_tlab_size() const {
2700 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2701 }
2702
2703 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2704 AllocationContext_t context = AllocationContext::current();
2705 return _allocator->unsafe_max_tlab_alloc(context);
2706 }
2707
2708 size_t G1CollectedHeap::max_capacity() const {
2709 return _hrm.reserved().byte_size();
2710 }
2711
2712 jlong G1CollectedHeap::millis_since_last_gc() {
2713 // assert(false, "NYI");
2714 return 0;
2715 }
2716
2717 void G1CollectedHeap::prepare_for_verify() {
2718 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2719 ensure_parsability(false);
2720 }
2721 g1_rem_set()->prepare_for_verify();
2722 }
2723
2724 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2725 VerifyOption vo) {
2726 switch (vo) {
2727 case VerifyOption_G1UsePrevMarking:
2728 return hr->obj_allocated_since_prev_marking(obj);
2729 case VerifyOption_G1UseNextMarking:
2730 return hr->obj_allocated_since_next_marking(obj);
2731 case VerifyOption_G1UseMarkWord:
2732 return false;
2733 default:
2734 ShouldNotReachHere();
2735 }
2736 return false; // keep some compilers happy
2737 }
2738
2739 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2740 switch (vo) {
2741 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2742 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2743 case VerifyOption_G1UseMarkWord: return NULL;
2744 default: ShouldNotReachHere();
2745 }
2746 return NULL; // keep some compilers happy
2747 }
2748
2749 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2750 switch (vo) {
2751 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2752 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2753 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2754 default: ShouldNotReachHere();
2755 }
2756 return false; // keep some compilers happy
2757 }
2758
2759 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2760 switch (vo) {
2761 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2762 case VerifyOption_G1UseNextMarking: return "NTAMS";
2763 case VerifyOption_G1UseMarkWord: return "NONE";
2764 default: ShouldNotReachHere();
2765 }
2766 return NULL; // keep some compilers happy
2767 }
2768
2769 class VerifyRootsClosure: public OopClosure {
2770 private:
2771 G1CollectedHeap* _g1h;
2772 VerifyOption _vo;
2773 bool _failures;
2774 public:
2775 // _vo == UsePrevMarking -> use "prev" marking information,
2776 // _vo == UseNextMarking -> use "next" marking information,
2777 // _vo == UseMarkWord -> use mark word from object header.
2778 VerifyRootsClosure(VerifyOption vo) :
2779 _g1h(G1CollectedHeap::heap()),
2780 _vo(vo),
2781 _failures(false) { }
2782
2783 bool failures() { return _failures; }
2784
2785 template <class T> void do_oop_nv(T* p) {
2786 T heap_oop = oopDesc::load_heap_oop(p);
2787 if (!oopDesc::is_null(heap_oop)) {
2788 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2789 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2790 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2791 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2792 if (_vo == VerifyOption_G1UseMarkWord) {
2793 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2794 }
2795 obj->print_on(gclog_or_tty);
2796 _failures = true;
2797 }
2798 }
2799 }
2800
2801 void do_oop(oop* p) { do_oop_nv(p); }
2802 void do_oop(narrowOop* p) { do_oop_nv(p); }
2803 };
2804
2805 class G1VerifyCodeRootOopClosure: public OopClosure {
2806 G1CollectedHeap* _g1h;
2807 OopClosure* _root_cl;
2808 nmethod* _nm;
2809 VerifyOption _vo;
2810 bool _failures;
2811
2812 template <class T> void do_oop_work(T* p) {
2813 // First verify that this root is live
2814 _root_cl->do_oop(p);
2815
2816 if (!G1VerifyHeapRegionCodeRoots) {
2817 // We're not verifying the code roots attached to heap region.
2818 return;
2819 }
2820
2821 // Don't check the code roots during marking verification in a full GC
2822 if (_vo == VerifyOption_G1UseMarkWord) {
2823 return;
2824 }
2825
2826 // Now verify that the current nmethod (which contains p) is
2827 // in the code root list of the heap region containing the
2828 // object referenced by p.
2829
2830 T heap_oop = oopDesc::load_heap_oop(p);
2831 if (!oopDesc::is_null(heap_oop)) {
2832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2833
2834 // Now fetch the region containing the object
2835 HeapRegion* hr = _g1h->heap_region_containing(obj);
2836 HeapRegionRemSet* hrrs = hr->rem_set();
2837 // Verify that the strong code root list for this region
2838 // contains the nmethod
2839 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2840 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2841 "from nmethod " PTR_FORMAT " not in strong "
2842 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2843 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2844 _failures = true;
2845 }
2846 }
2847 }
2848
2849 public:
2850 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2851 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2852
2853 void do_oop(oop* p) { do_oop_work(p); }
2854 void do_oop(narrowOop* p) { do_oop_work(p); }
2855
2856 void set_nmethod(nmethod* nm) { _nm = nm; }
2857 bool failures() { return _failures; }
2858 };
2859
2860 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2861 G1VerifyCodeRootOopClosure* _oop_cl;
2862
2863 public:
2864 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2865 _oop_cl(oop_cl) {}
2866
2867 void do_code_blob(CodeBlob* cb) {
2868 nmethod* nm = cb->as_nmethod_or_null();
2869 if (nm != NULL) {
2870 _oop_cl->set_nmethod(nm);
2871 nm->oops_do(_oop_cl);
2872 }
2873 }
2874 };
2875
2876 class YoungRefCounterClosure : public OopClosure {
2877 G1CollectedHeap* _g1h;
2878 int _count;
2879 public:
2880 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2881 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2882 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2883
2884 int count() { return _count; }
2885 void reset_count() { _count = 0; };
2886 };
2887
2888 class VerifyKlassClosure: public KlassClosure {
2889 YoungRefCounterClosure _young_ref_counter_closure;
2890 OopClosure *_oop_closure;
2891 public:
2892 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2893 void do_klass(Klass* k) {
2894 k->oops_do(_oop_closure);
2895
2896 _young_ref_counter_closure.reset_count();
2897 k->oops_do(&_young_ref_counter_closure);
2898 if (_young_ref_counter_closure.count() > 0) {
2899 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2900 }
2901 }
2902 };
2903
2904 class VerifyLivenessOopClosure: public OopClosure {
2905 G1CollectedHeap* _g1h;
2906 VerifyOption _vo;
2907 public:
2908 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2909 _g1h(g1h), _vo(vo)
2910 { }
2911 void do_oop(narrowOop *p) { do_oop_work(p); }
2912 void do_oop( oop *p) { do_oop_work(p); }
2913
2914 template <class T> void do_oop_work(T *p) {
2915 oop obj = oopDesc::load_decode_heap_oop(p);
2916 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2917 "Dead object referenced by a not dead object");
2918 }
2919 };
2920
2921 class VerifyObjsInRegionClosure: public ObjectClosure {
2922 private:
2923 G1CollectedHeap* _g1h;
2924 size_t _live_bytes;
2925 HeapRegion *_hr;
2926 VerifyOption _vo;
2927 public:
2928 // _vo == UsePrevMarking -> use "prev" marking information,
2929 // _vo == UseNextMarking -> use "next" marking information,
2930 // _vo == UseMarkWord -> use mark word from object header.
2931 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2932 : _live_bytes(0), _hr(hr), _vo(vo) {
2933 _g1h = G1CollectedHeap::heap();
2934 }
2935 void do_object(oop o) {
2936 VerifyLivenessOopClosure isLive(_g1h, _vo);
2937 assert(o != NULL, "Huh?");
2938 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2939 // If the object is alive according to the mark word,
2940 // then verify that the marking information agrees.
2941 // Note we can't verify the contra-positive of the
2942 // above: if the object is dead (according to the mark
2943 // word), it may not be marked, or may have been marked
2944 // but has since became dead, or may have been allocated
2945 // since the last marking.
2946 if (_vo == VerifyOption_G1UseMarkWord) {
2947 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2948 }
2949
2950 o->oop_iterate_no_header(&isLive);
2951 if (!_hr->obj_allocated_since_prev_marking(o)) {
2952 size_t obj_size = o->size(); // Make sure we don't overflow
2953 _live_bytes += (obj_size * HeapWordSize);
2954 }
2955 }
2956 }
2957 size_t live_bytes() { return _live_bytes; }
2958 };
2959
2960 class VerifyArchiveOopClosure: public OopClosure {
2961 public:
2962 VerifyArchiveOopClosure(HeapRegion *hr) { }
2963 void do_oop(narrowOop *p) { do_oop_work(p); }
2964 void do_oop( oop *p) { do_oop_work(p); }
2965
2966 template <class T> void do_oop_work(T *p) {
2967 oop obj = oopDesc::load_decode_heap_oop(p);
2968 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2969 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2970 p2i(p), p2i(obj));
2971 }
2972 };
2973
2974 class VerifyArchiveRegionClosure: public ObjectClosure {
2975 public:
2976 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2977 // Verify that all object pointers are to archive regions.
2978 void do_object(oop o) {
2979 VerifyArchiveOopClosure checkOop(NULL);
2980 assert(o != NULL, "Should not be here for NULL oops");
2981 o->oop_iterate_no_header(&checkOop);
2982 }
2983 };
2984
2985 class VerifyRegionClosure: public HeapRegionClosure {
2986 private:
2987 bool _par;
2988 VerifyOption _vo;
2989 bool _failures;
2990 public:
2991 // _vo == UsePrevMarking -> use "prev" marking information,
2992 // _vo == UseNextMarking -> use "next" marking information,
2993 // _vo == UseMarkWord -> use mark word from object header.
2994 VerifyRegionClosure(bool par, VerifyOption vo)
2995 : _par(par),
2996 _vo(vo),
2997 _failures(false) {}
2998
2999 bool failures() {
3000 return _failures;
3001 }
3002
3003 bool doHeapRegion(HeapRegion* r) {
3004 // For archive regions, verify there are no heap pointers to
3005 // non-pinned regions. For all others, verify liveness info.
3006 if (r->is_archive()) {
3007 VerifyArchiveRegionClosure verify_oop_pointers(r);
3008 r->object_iterate(&verify_oop_pointers);
3009 return true;
3010 }
3011 if (!r->is_continues_humongous()) {
3012 bool failures = false;
3013 r->verify(_vo, &failures);
3014 if (failures) {
3015 _failures = true;
3016 } else if (!r->is_starts_humongous()) {
3017 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3018 r->object_iterate(¬_dead_yet_cl);
3019 if (_vo != VerifyOption_G1UseNextMarking) {
3020 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3021 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3022 "max_live_bytes " SIZE_FORMAT " "
3023 "< calculated " SIZE_FORMAT,
3024 p2i(r->bottom()), p2i(r->end()),
3025 r->max_live_bytes(),
3026 not_dead_yet_cl.live_bytes());
3027 _failures = true;
3028 }
3029 } else {
3030 // When vo == UseNextMarking we cannot currently do a sanity
3031 // check on the live bytes as the calculation has not been
3032 // finalized yet.
3033 }
3034 }
3035 }
3036 return false; // stop the region iteration if we hit a failure
3037 }
3038 };
3039
3040 // This is the task used for parallel verification of the heap regions
3041
3042 class G1ParVerifyTask: public AbstractGangTask {
3043 private:
3044 G1CollectedHeap* _g1h;
3045 VerifyOption _vo;
3046 bool _failures;
3047 HeapRegionClaimer _hrclaimer;
3048
3049 public:
3050 // _vo == UsePrevMarking -> use "prev" marking information,
3051 // _vo == UseNextMarking -> use "next" marking information,
3052 // _vo == UseMarkWord -> use mark word from object header.
3053 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3054 AbstractGangTask("Parallel verify task"),
3055 _g1h(g1h),
3056 _vo(vo),
3057 _failures(false),
3058 _hrclaimer(g1h->workers()->active_workers()) {}
3059
3060 bool failures() {
3061 return _failures;
3062 }
3063
3064 void work(uint worker_id) {
3065 HandleMark hm;
3066 VerifyRegionClosure blk(true, _vo);
3067 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3068 if (blk.failures()) {
3069 _failures = true;
3070 }
3071 }
3072 };
3073
3074 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3075 if (SafepointSynchronize::is_at_safepoint()) {
3076 assert(Thread::current()->is_VM_thread(),
3077 "Expected to be executed serially by the VM thread at this point");
3078
3079 if (!silent) { gclog_or_tty->print("Roots "); }
3080 VerifyRootsClosure rootsCl(vo);
3081 VerifyKlassClosure klassCl(this, &rootsCl);
3082 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3083
3084 // We apply the relevant closures to all the oops in the
3085 // system dictionary, class loader data graph, the string table
3086 // and the nmethods in the code cache.
3087 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3088 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3089
3090 {
3091 G1RootProcessor root_processor(this, 1);
3092 root_processor.process_all_roots(&rootsCl,
3093 &cldCl,
3094 &blobsCl);
3095 }
3096
3097 bool failures = rootsCl.failures() || codeRootsCl.failures();
3098
3099 if (vo != VerifyOption_G1UseMarkWord) {
3100 // If we're verifying during a full GC then the region sets
3101 // will have been torn down at the start of the GC. Therefore
3102 // verifying the region sets will fail. So we only verify
3103 // the region sets when not in a full GC.
3104 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3105 verify_region_sets();
3106 }
3107
3108 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3109 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3110
3111 G1ParVerifyTask task(this, vo);
3112 workers()->run_task(&task);
3113 if (task.failures()) {
3114 failures = true;
3115 }
3116
3117 } else {
3118 VerifyRegionClosure blk(false, vo);
3119 heap_region_iterate(&blk);
3120 if (blk.failures()) {
3121 failures = true;
3122 }
3123 }
3124
3125 if (G1StringDedup::is_enabled()) {
3126 if (!silent) gclog_or_tty->print("StrDedup ");
3127 G1StringDedup::verify();
3128 }
3129
3130 if (failures) {
3131 gclog_or_tty->print_cr("Heap:");
3132 // It helps to have the per-region information in the output to
3133 // help us track down what went wrong. This is why we call
3134 // print_extended_on() instead of print_on().
3135 print_extended_on(gclog_or_tty);
3136 gclog_or_tty->cr();
3137 gclog_or_tty->flush();
3138 }
3139 guarantee(!failures, "there should not have been any failures");
3140 } else {
3141 if (!silent) {
3142 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3143 if (G1StringDedup::is_enabled()) {
3144 gclog_or_tty->print(", StrDedup");
3145 }
3146 gclog_or_tty->print(") ");
3147 }
3148 }
3149 }
3150
3151 void G1CollectedHeap::verify(bool silent) {
3152 verify(silent, VerifyOption_G1UsePrevMarking);
3153 }
3154
3155 double G1CollectedHeap::verify(bool guard, const char* msg) {
3156 double verify_time_ms = 0.0;
3157
3158 if (guard && total_collections() >= VerifyGCStartAt) {
3159 double verify_start = os::elapsedTime();
3160 HandleMark hm; // Discard invalid handles created during verification
3161 prepare_for_verify();
3162 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3163 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3164 }
3165
3166 return verify_time_ms;
3167 }
3168
3169 void G1CollectedHeap::verify_before_gc() {
3170 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3171 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3172 }
3173
3174 void G1CollectedHeap::verify_after_gc() {
3175 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3176 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3177 }
3178
3179 class PrintRegionClosure: public HeapRegionClosure {
3180 outputStream* _st;
3181 public:
3182 PrintRegionClosure(outputStream* st) : _st(st) {}
3183 bool doHeapRegion(HeapRegion* r) {
3184 r->print_on(_st);
3185 return false;
3186 }
3187 };
3188
3189 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3190 const HeapRegion* hr,
3191 const VerifyOption vo) const {
3192 switch (vo) {
3193 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3194 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3195 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3196 default: ShouldNotReachHere();
3197 }
3198 return false; // keep some compilers happy
3199 }
3200
3201 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3202 const VerifyOption vo) const {
3203 switch (vo) {
3204 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3205 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3206 case VerifyOption_G1UseMarkWord: {
3207 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3208 return !obj->is_gc_marked() && !hr->is_archive();
3209 }
3210 default: ShouldNotReachHere();
3211 }
3212 return false; // keep some compilers happy
3213 }
3214
3215 void G1CollectedHeap::print_on(outputStream* st) const {
3216 st->print(" %-20s", "garbage-first heap");
3217 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3218 capacity()/K, used_unlocked()/K);
3219 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3220 p2i(_hrm.reserved().start()),
3221 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3222 p2i(_hrm.reserved().end()));
3223 st->cr();
3224 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3225 uint young_regions = _young_list->length();
3226 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3227 (size_t) young_regions * HeapRegion::GrainBytes / K);
3228 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3229 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3230 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3231 st->cr();
3232 MetaspaceAux::print_on(st);
3233 }
3234
3235 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3236 print_on(st);
3237
3238 // Print the per-region information.
3239 st->cr();
3240 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3241 "HS=humongous(starts), HC=humongous(continues), "
3242 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3243 "PTAMS=previous top-at-mark-start, "
3244 "NTAMS=next top-at-mark-start)");
3245 PrintRegionClosure blk(st);
3246 heap_region_iterate(&blk);
3247 }
3248
3249 void G1CollectedHeap::print_on_error(outputStream* st) const {
3250 this->CollectedHeap::print_on_error(st);
3251
3252 if (_cm != NULL) {
3253 st->cr();
3254 _cm->print_on_error(st);
3255 }
3256 }
3257
3258 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3259 workers()->print_worker_threads_on(st);
3260 _cmThread->print_on(st);
3261 st->cr();
3262 _cm->print_worker_threads_on(st);
3263 _cg1r->print_worker_threads_on(st);
3264 if (G1StringDedup::is_enabled()) {
3265 G1StringDedup::print_worker_threads_on(st);
3266 }
3267 }
3268
3269 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3270 workers()->threads_do(tc);
3271 tc->do_thread(_cmThread);
3272 _cg1r->threads_do(tc);
3273 if (G1StringDedup::is_enabled()) {
3274 G1StringDedup::threads_do(tc);
3275 }
3276 }
3277
3278 void G1CollectedHeap::print_tracing_info() const {
3279 // We'll overload this to mean "trace GC pause statistics."
3280 if (TraceYoungGenTime || TraceOldGenTime) {
3281 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3282 // to that.
3283 g1_policy()->print_tracing_info();
3284 }
3285 if (G1SummarizeRSetStats) {
3286 g1_rem_set()->print_summary_info();
3287 }
3288 if (G1SummarizeConcMark) {
3289 concurrent_mark()->print_summary_info();
3290 }
3291 g1_policy()->print_yg_surv_rate_info();
3292 }
3293
3294 #ifndef PRODUCT
3295 // Helpful for debugging RSet issues.
3296
3297 class PrintRSetsClosure : public HeapRegionClosure {
3298 private:
3299 const char* _msg;
3300 size_t _occupied_sum;
3301
3302 public:
3303 bool doHeapRegion(HeapRegion* r) {
3304 HeapRegionRemSet* hrrs = r->rem_set();
3305 size_t occupied = hrrs->occupied();
3306 _occupied_sum += occupied;
3307
3308 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3309 HR_FORMAT_PARAMS(r));
3310 if (occupied == 0) {
3311 gclog_or_tty->print_cr(" RSet is empty");
3312 } else {
3313 hrrs->print();
3314 }
3315 gclog_or_tty->print_cr("----------");
3316 return false;
3317 }
3318
3319 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3320 gclog_or_tty->cr();
3321 gclog_or_tty->print_cr("========================================");
3322 gclog_or_tty->print_cr("%s", msg);
3323 gclog_or_tty->cr();
3324 }
3325
3326 ~PrintRSetsClosure() {
3327 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3328 gclog_or_tty->print_cr("========================================");
3329 gclog_or_tty->cr();
3330 }
3331 };
3332
3333 void G1CollectedHeap::print_cset_rsets() {
3334 PrintRSetsClosure cl("Printing CSet RSets");
3335 collection_set_iterate(&cl);
3336 }
3337
3338 void G1CollectedHeap::print_all_rsets() {
3339 PrintRSetsClosure cl("Printing All RSets");;
3340 heap_region_iterate(&cl);
3341 }
3342 #endif // PRODUCT
3343
3344 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3345 YoungList* young_list = heap()->young_list();
3346
3347 size_t eden_used_bytes = young_list->eden_used_bytes();
3348 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3349
3350 size_t eden_capacity_bytes =
3351 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3352
3353 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3354 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3355 }
3356
3357 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3358 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3359 stats->unused(), stats->used(), stats->region_end_waste(),
3360 stats->regions_filled(), stats->direct_allocated(),
3361 stats->failure_used(), stats->failure_waste());
3362 }
3363
3364 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3365 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3366 gc_tracer->report_gc_heap_summary(when, heap_summary);
3367
3368 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3369 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3370 }
3371
3372
3373 G1CollectedHeap* G1CollectedHeap::heap() {
3374 CollectedHeap* heap = Universe::heap();
3375 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3376 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3377 return (G1CollectedHeap*)heap;
3378 }
3379
3380 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3381 // always_do_update_barrier = false;
3382 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3383 // Fill TLAB's and such
3384 accumulate_statistics_all_tlabs();
3385 ensure_parsability(true);
3386
3387 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3388 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3389 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3390 }
3391 }
3392
3393 void G1CollectedHeap::gc_epilogue(bool full) {
3394
3395 if (G1SummarizeRSetStats &&
3396 (G1SummarizeRSetStatsPeriod > 0) &&
3397 // we are at the end of the GC. Total collections has already been increased.
3398 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3399 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3400 }
3401
3402 // FIXME: what is this about?
3403 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3404 // is set.
3405 #if defined(COMPILER2) || INCLUDE_JVMCI
3406 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3407 #endif
3408 // always_do_update_barrier = true;
3409
3410 resize_all_tlabs();
3411 allocation_context_stats().update(full);
3412
3413 // We have just completed a GC. Update the soft reference
3414 // policy with the new heap occupancy
3415 Universe::update_heap_info_at_gc();
3416 }
3417
3418 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3419 uint gc_count_before,
3420 bool* succeeded,
3421 GCCause::Cause gc_cause) {
3422 assert_heap_not_locked_and_not_at_safepoint();
3423 g1_policy()->record_stop_world_start();
3424 VM_G1IncCollectionPause op(gc_count_before,
3425 word_size,
3426 false, /* should_initiate_conc_mark */
3427 g1_policy()->max_pause_time_ms(),
3428 gc_cause);
3429
3430 op.set_allocation_context(AllocationContext::current());
3431 VMThread::execute(&op);
3432
3433 HeapWord* result = op.result();
3434 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3435 assert(result == NULL || ret_succeeded,
3436 "the result should be NULL if the VM did not succeed");
3437 *succeeded = ret_succeeded;
3438
3439 assert_heap_not_locked();
3440 return result;
3441 }
3442
3443 void
3444 G1CollectedHeap::doConcurrentMark() {
3445 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3446 if (!_cmThread->in_progress()) {
3447 _cmThread->set_started();
3448 CGC_lock->notify();
3449 }
3450 }
3451
3452 size_t G1CollectedHeap::pending_card_num() {
3453 size_t extra_cards = 0;
3454 JavaThread *curr = Threads::first();
3455 while (curr != NULL) {
3456 DirtyCardQueue& dcq = curr->dirty_card_queue();
3457 extra_cards += dcq.size();
3458 curr = curr->next();
3459 }
3460 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3461 size_t buffer_size = dcqs.buffer_size();
3462 size_t buffer_num = dcqs.completed_buffers_num();
3463
3464 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3465 // in bytes - not the number of 'entries'. We need to convert
3466 // into a number of cards.
3467 return (buffer_size * buffer_num + extra_cards) / oopSize;
3468 }
3469
3470 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3471 private:
3472 size_t _total_humongous;
3473 size_t _candidate_humongous;
3474
3475 DirtyCardQueue _dcq;
3476
3477 // We don't nominate objects with many remembered set entries, on
3478 // the assumption that such objects are likely still live.
3479 bool is_remset_small(HeapRegion* region) const {
3480 HeapRegionRemSet* const rset = region->rem_set();
3481 return G1EagerReclaimHumongousObjectsWithStaleRefs
3482 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3483 : rset->is_empty();
3484 }
3485
3486 bool is_typeArray_region(HeapRegion* region) const {
3487 return oop(region->bottom())->is_typeArray();
3488 }
3489
3490 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3491 assert(region->is_starts_humongous(), "Must start a humongous object");
3492
3493 // Candidate selection must satisfy the following constraints
3494 // while concurrent marking is in progress:
3495 //
3496 // * In order to maintain SATB invariants, an object must not be
3497 // reclaimed if it was allocated before the start of marking and
3498 // has not had its references scanned. Such an object must have
3499 // its references (including type metadata) scanned to ensure no
3500 // live objects are missed by the marking process. Objects
3501 // allocated after the start of concurrent marking don't need to
3502 // be scanned.
3503 //
3504 // * An object must not be reclaimed if it is on the concurrent
3505 // mark stack. Objects allocated after the start of concurrent
3506 // marking are never pushed on the mark stack.
3507 //
3508 // Nominating only objects allocated after the start of concurrent
3509 // marking is sufficient to meet both constraints. This may miss
3510 // some objects that satisfy the constraints, but the marking data
3511 // structures don't support efficiently performing the needed
3512 // additional tests or scrubbing of the mark stack.
3513 //
3514 // However, we presently only nominate is_typeArray() objects.
3515 // A humongous object containing references induces remembered
3516 // set entries on other regions. In order to reclaim such an
3517 // object, those remembered sets would need to be cleaned up.
3518 //
3519 // We also treat is_typeArray() objects specially, allowing them
3520 // to be reclaimed even if allocated before the start of
3521 // concurrent mark. For this we rely on mark stack insertion to
3522 // exclude is_typeArray() objects, preventing reclaiming an object
3523 // that is in the mark stack. We also rely on the metadata for
3524 // such objects to be built-in and so ensured to be kept live.
3525 // Frequent allocation and drop of large binary blobs is an
3526 // important use case for eager reclaim, and this special handling
3527 // may reduce needed headroom.
3528
3529 return is_typeArray_region(region) && is_remset_small(region);
3530 }
3531
3532 public:
3533 RegisterHumongousWithInCSetFastTestClosure()
3534 : _total_humongous(0),
3535 _candidate_humongous(0),
3536 _dcq(&JavaThread::dirty_card_queue_set()) {
3537 }
3538
3539 virtual bool doHeapRegion(HeapRegion* r) {
3540 if (!r->is_starts_humongous()) {
3541 return false;
3542 }
3543 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3544
3545 bool is_candidate = humongous_region_is_candidate(g1h, r);
3546 uint rindex = r->hrm_index();
3547 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3548 if (is_candidate) {
3549 _candidate_humongous++;
3550 g1h->register_humongous_region_with_cset(rindex);
3551 // Is_candidate already filters out humongous object with large remembered sets.
3552 // If we have a humongous object with a few remembered sets, we simply flush these
3553 // remembered set entries into the DCQS. That will result in automatic
3554 // re-evaluation of their remembered set entries during the following evacuation
3555 // phase.
3556 if (!r->rem_set()->is_empty()) {
3557 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3558 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3559 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3560 HeapRegionRemSetIterator hrrs(r->rem_set());
3561 size_t card_index;
3562 while (hrrs.has_next(card_index)) {
3563 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3564 // The remembered set might contain references to already freed
3565 // regions. Filter out such entries to avoid failing card table
3566 // verification.
3567 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3568 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3569 *card_ptr = CardTableModRefBS::dirty_card_val();
3570 _dcq.enqueue(card_ptr);
3571 }
3572 }
3573 }
3574 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3575 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3576 hrrs.n_yielded(), r->rem_set()->occupied());
3577 r->rem_set()->clear_locked();
3578 }
3579 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3580 }
3581 _total_humongous++;
3582
3583 return false;
3584 }
3585
3586 size_t total_humongous() const { return _total_humongous; }
3587 size_t candidate_humongous() const { return _candidate_humongous; }
3588
3589 void flush_rem_set_entries() { _dcq.flush(); }
3590 };
3591
3592 void G1CollectedHeap::register_humongous_regions_with_cset() {
3593 if (!G1EagerReclaimHumongousObjects) {
3594 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3595 return;
3596 }
3597 double time = os::elapsed_counter();
3598
3599 // Collect reclaim candidate information and register candidates with cset.
3600 RegisterHumongousWithInCSetFastTestClosure cl;
3601 heap_region_iterate(&cl);
3602
3603 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3604 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3605 cl.total_humongous(),
3606 cl.candidate_humongous());
3607 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3608
3609 // Finally flush all remembered set entries to re-check into the global DCQS.
3610 cl.flush_rem_set_entries();
3611 }
3612
3613 #ifdef ASSERT
3614 class VerifyCSetClosure: public HeapRegionClosure {
3615 public:
3616 bool doHeapRegion(HeapRegion* hr) {
3617 // Here we check that the CSet region's RSet is ready for parallel
3618 // iteration. The fields that we'll verify are only manipulated
3619 // when the region is part of a CSet and is collected. Afterwards,
3620 // we reset these fields when we clear the region's RSet (when the
3621 // region is freed) so they are ready when the region is
3622 // re-allocated. The only exception to this is if there's an
3623 // evacuation failure and instead of freeing the region we leave
3624 // it in the heap. In that case, we reset these fields during
3625 // evacuation failure handling.
3626 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3627
3628 // Here's a good place to add any other checks we'd like to
3629 // perform on CSet regions.
3630 return false;
3631 }
3632 };
3633 #endif // ASSERT
3634
3635 uint G1CollectedHeap::num_task_queues() const {
3636 return _task_queues->size();
3637 }
3638
3639 #if TASKQUEUE_STATS
3640 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3641 st->print_raw_cr("GC Task Stats");
3642 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3643 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3644 }
3645
3646 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3647 print_taskqueue_stats_hdr(st);
3648
3649 TaskQueueStats totals;
3650 const uint n = num_task_queues();
3651 for (uint i = 0; i < n; ++i) {
3652 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3653 totals += task_queue(i)->stats;
3654 }
3655 st->print_raw("tot "); totals.print(st); st->cr();
3656
3657 DEBUG_ONLY(totals.verify());
3658 }
3659
3660 void G1CollectedHeap::reset_taskqueue_stats() {
3661 const uint n = num_task_queues();
3662 for (uint i = 0; i < n; ++i) {
3663 task_queue(i)->stats.reset();
3664 }
3665 }
3666 #endif // TASKQUEUE_STATS
3667
3668 void G1CollectedHeap::log_gc_header() {
3669 if (!G1Log::fine()) {
3670 return;
3671 }
3672
3673 gclog_or_tty->gclog_stamp();
3674
3675 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3676 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3677 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3678
3679 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3680 }
3681
3682 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3683 if (!G1Log::fine()) {
3684 return;
3685 }
3686
3687 if (G1Log::finer()) {
3688 if (evacuation_failed()) {
3689 gclog_or_tty->print(" (to-space exhausted)");
3690 }
3691 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3692 g1_policy()->print_phases(pause_time_sec);
3693 g1_policy()->print_detailed_heap_transition();
3694 } else {
3695 if (evacuation_failed()) {
3696 gclog_or_tty->print("--");
3697 }
3698 g1_policy()->print_heap_transition();
3699 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3700 }
3701 gclog_or_tty->flush();
3702 }
3703
3704 void G1CollectedHeap::wait_for_root_region_scanning() {
3705 double scan_wait_start = os::elapsedTime();
3706 // We have to wait until the CM threads finish scanning the
3707 // root regions as it's the only way to ensure that all the
3708 // objects on them have been correctly scanned before we start
3709 // moving them during the GC.
3710 bool waited = _cm->root_regions()->wait_until_scan_finished();
3711 double wait_time_ms = 0.0;
3712 if (waited) {
3713 double scan_wait_end = os::elapsedTime();
3714 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3715 }
3716 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3717 }
3718
3719 bool
3720 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3721 assert_at_safepoint(true /* should_be_vm_thread */);
3722 guarantee(!is_gc_active(), "collection is not reentrant");
3723
3724 if (GC_locker::check_active_before_gc()) {
3725 return false;
3726 }
3727
3728 _gc_timer_stw->register_gc_start();
3729
3730 GCIdMark gc_id_mark;
3731 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3732
3733 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3734 ResourceMark rm;
3735
3736 wait_for_root_region_scanning();
3737
3738 G1Log::update_level();
3739 print_heap_before_gc();
3740 trace_heap_before_gc(_gc_tracer_stw);
3741
3742 verify_region_sets_optional();
3743 verify_dirty_young_regions();
3744
3745 // This call will decide whether this pause is an initial-mark
3746 // pause. If it is, during_initial_mark_pause() will return true
3747 // for the duration of this pause.
3748 g1_policy()->decide_on_conc_mark_initiation();
3749
3750 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3751 assert(!collector_state()->during_initial_mark_pause() ||
3752 collector_state()->gcs_are_young(), "sanity");
3753
3754 // We also do not allow mixed GCs during marking.
3755 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3756
3757 // Record whether this pause is an initial mark. When the current
3758 // thread has completed its logging output and it's safe to signal
3759 // the CM thread, the flag's value in the policy has been reset.
3760 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3761
3762 // Inner scope for scope based logging, timers, and stats collection
3763 {
3764 EvacuationInfo evacuation_info;
3765
3766 if (collector_state()->during_initial_mark_pause()) {
3767 // We are about to start a marking cycle, so we increment the
3768 // full collection counter.
3769 increment_old_marking_cycles_started();
3770 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3771 }
3772
3773 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3774
3775 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3776
3777 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3778 workers()->active_workers(),
3779 Threads::number_of_non_daemon_threads());
3780 workers()->set_active_workers(active_workers);
3781
3782 double pause_start_sec = os::elapsedTime();
3783 g1_policy()->note_gc_start(active_workers);
3784 log_gc_header();
3785
3786 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3787 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3788
3789 // If the secondary_free_list is not empty, append it to the
3790 // free_list. No need to wait for the cleanup operation to finish;
3791 // the region allocation code will check the secondary_free_list
3792 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3793 // set, skip this step so that the region allocation code has to
3794 // get entries from the secondary_free_list.
3795 if (!G1StressConcRegionFreeing) {
3796 append_secondary_free_list_if_not_empty_with_lock();
3797 }
3798
3799 assert(check_young_list_well_formed(), "young list should be well formed");
3800
3801 // Don't dynamically change the number of GC threads this early. A value of
3802 // 0 is used to indicate serial work. When parallel work is done,
3803 // it will be set.
3804
3805 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3806 IsGCActiveMark x;
3807
3808 gc_prologue(false);
3809 increment_total_collections(false /* full gc */);
3810 increment_gc_time_stamp();
3811
3812 verify_before_gc();
3813
3814 check_bitmaps("GC Start");
3815
3816 #if defined(COMPILER2) || INCLUDE_JVMCI
3817 DerivedPointerTable::clear();
3818 #endif
3819
3820 // Please see comment in g1CollectedHeap.hpp and
3821 // G1CollectedHeap::ref_processing_init() to see how
3822 // reference processing currently works in G1.
3823
3824 // Enable discovery in the STW reference processor
3825 ref_processor_stw()->enable_discovery();
3826
3827 {
3828 // We want to temporarily turn off discovery by the
3829 // CM ref processor, if necessary, and turn it back on
3830 // on again later if we do. Using a scoped
3831 // NoRefDiscovery object will do this.
3832 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3833
3834 // Forget the current alloc region (we might even choose it to be part
3835 // of the collection set!).
3836 _allocator->release_mutator_alloc_region();
3837
3838 // We should call this after we retire the mutator alloc
3839 // region(s) so that all the ALLOC / RETIRE events are generated
3840 // before the start GC event.
3841 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3842
3843 // This timing is only used by the ergonomics to handle our pause target.
3844 // It is unclear why this should not include the full pause. We will
3845 // investigate this in CR 7178365.
3846 //
3847 // Preserving the old comment here if that helps the investigation:
3848 //
3849 // The elapsed time induced by the start time below deliberately elides
3850 // the possible verification above.
3851 double sample_start_time_sec = os::elapsedTime();
3852
3853 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3854
3855 if (collector_state()->during_initial_mark_pause()) {
3856 concurrent_mark()->checkpointRootsInitialPre();
3857 }
3858
3859 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3860 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3861
3862 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3863
3864 // Make sure the remembered sets are up to date. This needs to be
3865 // done before register_humongous_regions_with_cset(), because the
3866 // remembered sets are used there to choose eager reclaim candidates.
3867 // If the remembered sets are not up to date we might miss some
3868 // entries that need to be handled.
3869 g1_rem_set()->cleanupHRRS();
3870
3871 register_humongous_regions_with_cset();
3872
3873 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3874
3875 _cm->note_start_of_gc();
3876 // We call this after finalize_cset() to
3877 // ensure that the CSet has been finalized.
3878 _cm->verify_no_cset_oops();
3879
3880 if (_hr_printer.is_active()) {
3881 HeapRegion* hr = g1_policy()->collection_set();
3882 while (hr != NULL) {
3883 _hr_printer.cset(hr);
3884 hr = hr->next_in_collection_set();
3885 }
3886 }
3887
3888 #ifdef ASSERT
3889 VerifyCSetClosure cl;
3890 collection_set_iterate(&cl);
3891 #endif // ASSERT
3892
3893 // Initialize the GC alloc regions.
3894 _allocator->init_gc_alloc_regions(evacuation_info);
3895
3896 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3897 pre_evacuate_collection_set();
3898
3899 // Actually do the work...
3900 evacuate_collection_set(evacuation_info, &per_thread_states);
3901
3902 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3903
3904 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3905 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3906
3907 eagerly_reclaim_humongous_regions();
3908
3909 g1_policy()->clear_collection_set();
3910
3911 // Start a new incremental collection set for the next pause.
3912 g1_policy()->start_incremental_cset_building();
3913
3914 clear_cset_fast_test();
3915
3916 _young_list->reset_sampled_info();
3917
3918 // Don't check the whole heap at this point as the
3919 // GC alloc regions from this pause have been tagged
3920 // as survivors and moved on to the survivor list.
3921 // Survivor regions will fail the !is_young() check.
3922 assert(check_young_list_empty(false /* check_heap */),
3923 "young list should be empty");
3924
3925 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3926 _young_list->first_survivor_region(),
3927 _young_list->last_survivor_region());
3928
3929 _young_list->reset_auxilary_lists();
3930
3931 if (evacuation_failed()) {
3932 set_used(recalculate_used());
3933 if (_archive_allocator != NULL) {
3934 _archive_allocator->clear_used();
3935 }
3936 for (uint i = 0; i < ParallelGCThreads; i++) {
3937 if (_evacuation_failed_info_array[i].has_failed()) {
3938 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3939 }
3940 }
3941 } else {
3942 // The "used" of the the collection set have already been subtracted
3943 // when they were freed. Add in the bytes evacuated.
3944 increase_used(g1_policy()->bytes_copied_during_gc());
3945 }
3946
3947 if (collector_state()->during_initial_mark_pause()) {
3948 // We have to do this before we notify the CM threads that
3949 // they can start working to make sure that all the
3950 // appropriate initialization is done on the CM object.
3951 concurrent_mark()->checkpointRootsInitialPost();
3952 collector_state()->set_mark_in_progress(true);
3953 // Note that we don't actually trigger the CM thread at
3954 // this point. We do that later when we're sure that
3955 // the current thread has completed its logging output.
3956 }
3957
3958 allocate_dummy_regions();
3959
3960 _allocator->init_mutator_alloc_region();
3961
3962 {
3963 size_t expand_bytes = g1_policy()->expansion_amount();
3964 if (expand_bytes > 0) {
3965 size_t bytes_before = capacity();
3966 // No need for an ergo verbose message here,
3967 // expansion_amount() does this when it returns a value > 0.
3968 double expand_ms;
3969 if (!expand(expand_bytes, &expand_ms)) {
3970 // We failed to expand the heap. Cannot do anything about it.
3971 }
3972 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3973 }
3974 }
3975
3976 // We redo the verification but now wrt to the new CSet which
3977 // has just got initialized after the previous CSet was freed.
3978 _cm->verify_no_cset_oops();
3979 _cm->note_end_of_gc();
3980
3981 // This timing is only used by the ergonomics to handle our pause target.
3982 // It is unclear why this should not include the full pause. We will
3983 // investigate this in CR 7178365.
3984 double sample_end_time_sec = os::elapsedTime();
3985 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3986 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3987 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3988
3989 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3990 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3991
3992 MemoryService::track_memory_usage();
3993
3994 // In prepare_for_verify() below we'll need to scan the deferred
3995 // update buffers to bring the RSets up-to-date if
3996 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3997 // the update buffers we'll probably need to scan cards on the
3998 // regions we just allocated to (i.e., the GC alloc
3999 // regions). However, during the last GC we called
4000 // set_saved_mark() on all the GC alloc regions, so card
4001 // scanning might skip the [saved_mark_word()...top()] area of
4002 // those regions (i.e., the area we allocated objects into
4003 // during the last GC). But it shouldn't. Given that
4004 // saved_mark_word() is conditional on whether the GC time stamp
4005 // on the region is current or not, by incrementing the GC time
4006 // stamp here we invalidate all the GC time stamps on all the
4007 // regions and saved_mark_word() will simply return top() for
4008 // all the regions. This is a nicer way of ensuring this rather
4009 // than iterating over the regions and fixing them. In fact, the
4010 // GC time stamp increment here also ensures that
4011 // saved_mark_word() will return top() between pauses, i.e.,
4012 // during concurrent refinement. So we don't need the
4013 // is_gc_active() check to decided which top to use when
4014 // scanning cards (see CR 7039627).
4015 increment_gc_time_stamp();
4016
4017 verify_after_gc();
4018 check_bitmaps("GC End");
4019
4020 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4021 ref_processor_stw()->verify_no_references_recorded();
4022
4023 // CM reference discovery will be re-enabled if necessary.
4024 }
4025
4026 // We should do this after we potentially expand the heap so
4027 // that all the COMMIT events are generated before the end GC
4028 // event, and after we retire the GC alloc regions so that all
4029 // RETIRE events are generated before the end GC event.
4030 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4031
4032 #ifdef TRACESPINNING
4033 ParallelTaskTerminator::print_termination_counts();
4034 #endif
4035
4036 gc_epilogue(false);
4037 }
4038
4039 // Print the remainder of the GC log output.
4040 log_gc_footer(os::elapsedTime() - pause_start_sec);
4041
4042 // It is not yet to safe to tell the concurrent mark to
4043 // start as we have some optional output below. We don't want the
4044 // output from the concurrent mark thread interfering with this
4045 // logging output either.
4046
4047 _hrm.verify_optional();
4048 verify_region_sets_optional();
4049
4050 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4051 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4052
4053 print_heap_after_gc();
4054 trace_heap_after_gc(_gc_tracer_stw);
4055
4056 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4057 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4058 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4059 // before any GC notifications are raised.
4060 g1mm()->update_sizes();
4061
4062 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4063 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4064 _gc_timer_stw->register_gc_end();
4065 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4066 }
4067 // It should now be safe to tell the concurrent mark thread to start
4068 // without its logging output interfering with the logging output
4069 // that came from the pause.
4070
4071 if (should_start_conc_mark) {
4072 // CAUTION: after the doConcurrentMark() call below,
4073 // the concurrent marking thread(s) could be running
4074 // concurrently with us. Make sure that anything after
4075 // this point does not assume that we are the only GC thread
4076 // running. Note: of course, the actual marking work will
4077 // not start until the safepoint itself is released in
4078 // SuspendibleThreadSet::desynchronize().
4079 doConcurrentMark();
4080 }
4081
4082 return true;
4083 }
4084
4085 void G1CollectedHeap::remove_self_forwarding_pointers() {
4086 double remove_self_forwards_start = os::elapsedTime();
4087
4088 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4089 workers()->run_task(&rsfp_task);
4090
4091 // Now restore saved marks, if any.
4092 for (uint i = 0; i < ParallelGCThreads; i++) {
4093 OopAndMarkOopStack& cur = _preserved_objs[i];
4094 while (!cur.is_empty()) {
4095 OopAndMarkOop elem = cur.pop();
4096 elem.set_mark();
4097 }
4098 cur.clear(true);
4099 }
4100
4101 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4102 }
4103
4104 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4105 if (!_evacuation_failed) {
4106 _evacuation_failed = true;
4107 }
4108
4109 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4110
4111 // We want to call the "for_promotion_failure" version only in the
4112 // case of a promotion failure.
4113 if (m->must_be_preserved_for_promotion_failure(obj)) {
4114 OopAndMarkOop elem(obj, m);
4115 _preserved_objs[worker_id].push(elem);
4116 }
4117 }
4118
4119 class G1ParEvacuateFollowersClosure : public VoidClosure {
4120 private:
4121 double _start_term;
4122 double _term_time;
4123 size_t _term_attempts;
4124
4125 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4126 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4127 protected:
4128 G1CollectedHeap* _g1h;
4129 G1ParScanThreadState* _par_scan_state;
4130 RefToScanQueueSet* _queues;
4131 ParallelTaskTerminator* _terminator;
4132
4133 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4134 RefToScanQueueSet* queues() { return _queues; }
4135 ParallelTaskTerminator* terminator() { return _terminator; }
4136
4137 public:
4138 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4139 G1ParScanThreadState* par_scan_state,
4140 RefToScanQueueSet* queues,
4141 ParallelTaskTerminator* terminator)
4142 : _g1h(g1h), _par_scan_state(par_scan_state),
4143 _queues(queues), _terminator(terminator),
4144 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4145
4146 void do_void();
4147
4148 double term_time() const { return _term_time; }
4149 size_t term_attempts() const { return _term_attempts; }
4150
4151 private:
4152 inline bool offer_termination();
4153 };
4154
4155 bool G1ParEvacuateFollowersClosure::offer_termination() {
4156 G1ParScanThreadState* const pss = par_scan_state();
4157 start_term_time();
4158 const bool res = terminator()->offer_termination();
4159 end_term_time();
4160 return res;
4161 }
4162
4163 void G1ParEvacuateFollowersClosure::do_void() {
4164 G1ParScanThreadState* const pss = par_scan_state();
4165 pss->trim_queue();
4166 do {
4167 pss->steal_and_trim_queue(queues());
4168 } while (!offer_termination());
4169 }
4170
4171 class G1ParTask : public AbstractGangTask {
4172 protected:
4173 G1CollectedHeap* _g1h;
4174 G1ParScanThreadStateSet* _pss;
4175 RefToScanQueueSet* _queues;
4176 G1RootProcessor* _root_processor;
4177 ParallelTaskTerminator _terminator;
4178 uint _n_workers;
4179
4180 public:
4181 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4182 : AbstractGangTask("G1 collection"),
4183 _g1h(g1h),
4184 _pss(per_thread_states),
4185 _queues(task_queues),
4186 _root_processor(root_processor),
4187 _terminator(n_workers, _queues),
4188 _n_workers(n_workers)
4189 {}
4190
4191 void work(uint worker_id) {
4192 if (worker_id >= _n_workers) return; // no work needed this round
4193
4194 double start_sec = os::elapsedTime();
4195 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4196
4197 {
4198 ResourceMark rm;
4199 HandleMark hm;
4200
4201 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4202
4203 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4204 pss->set_ref_processor(rp);
4205
4206 double start_strong_roots_sec = os::elapsedTime();
4207
4208 _root_processor->evacuate_roots(pss->closures(), worker_id);
4209
4210 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4211
4212 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4213 // treating the nmethods visited to act as roots for concurrent marking.
4214 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4215 // objects copied by the current evacuation.
4216 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4217 pss->closures()->weak_codeblobs(),
4218 worker_id);
4219
4220 _pss->add_cards_scanned(worker_id, cards_scanned);
4221
4222 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4223
4224 double term_sec = 0.0;
4225 size_t evac_term_attempts = 0;
4226 {
4227 double start = os::elapsedTime();
4228 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4229 evac.do_void();
4230
4231 evac_term_attempts = evac.term_attempts();
4232 term_sec = evac.term_time();
4233 double elapsed_sec = os::elapsedTime() - start;
4234 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4235 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4236 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4237 }
4238
4239 assert(pss->queue_is_empty(), "should be empty");
4240
4241 if (PrintTerminationStats) {
4242 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4243 size_t lab_waste;
4244 size_t lab_undo_waste;
4245 pss->waste(lab_waste, lab_undo_waste);
4246 _g1h->print_termination_stats(gclog_or_tty,
4247 worker_id,
4248 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4249 strong_roots_sec * 1000.0, /* strong roots time */
4250 term_sec * 1000.0, /* evac term time */
4251 evac_term_attempts, /* evac term attempts */
4252 lab_waste, /* alloc buffer waste */
4253 lab_undo_waste /* undo waste */
4254 );
4255 }
4256
4257 // Close the inner scope so that the ResourceMark and HandleMark
4258 // destructors are executed here and are included as part of the
4259 // "GC Worker Time".
4260 }
4261 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4262 }
4263 };
4264
4265 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4266 st->print_raw_cr("GC Termination Stats");
4267 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4268 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4269 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4270 }
4271
4272 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4273 uint worker_id,
4274 double elapsed_ms,
4275 double strong_roots_ms,
4276 double term_ms,
4277 size_t term_attempts,
4278 size_t alloc_buffer_waste,
4279 size_t undo_waste) const {
4280 st->print_cr("%3d %9.2f %9.2f %6.2f "
4281 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4282 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4283 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4284 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4285 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4286 alloc_buffer_waste * HeapWordSize / K,
4287 undo_waste * HeapWordSize / K);
4288 }
4289
4290 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4291 private:
4292 BoolObjectClosure* _is_alive;
4293 int _initial_string_table_size;
4294 int _initial_symbol_table_size;
4295
4296 bool _process_strings;
4297 int _strings_processed;
4298 int _strings_removed;
4299
4300 bool _process_symbols;
4301 int _symbols_processed;
4302 int _symbols_removed;
4303
4304 public:
4305 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4306 AbstractGangTask("String/Symbol Unlinking"),
4307 _is_alive(is_alive),
4308 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4309 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4310
4311 _initial_string_table_size = StringTable::the_table()->table_size();
4312 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4313 if (process_strings) {
4314 StringTable::clear_parallel_claimed_index();
4315 }
4316 if (process_symbols) {
4317 SymbolTable::clear_parallel_claimed_index();
4318 }
4319 }
4320
4321 ~G1StringSymbolTableUnlinkTask() {
4322 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4323 "claim value %d after unlink less than initial string table size %d",
4324 StringTable::parallel_claimed_index(), _initial_string_table_size);
4325 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4326 "claim value %d after unlink less than initial symbol table size %d",
4327 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4328
4329 if (G1TraceStringSymbolTableScrubbing) {
4330 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4331 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4332 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4333 strings_processed(), strings_removed(),
4334 symbols_processed(), symbols_removed());
4335 }
4336 }
4337
4338 void work(uint worker_id) {
4339 int strings_processed = 0;
4340 int strings_removed = 0;
4341 int symbols_processed = 0;
4342 int symbols_removed = 0;
4343 if (_process_strings) {
4344 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4345 Atomic::add(strings_processed, &_strings_processed);
4346 Atomic::add(strings_removed, &_strings_removed);
4347 }
4348 if (_process_symbols) {
4349 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4350 Atomic::add(symbols_processed, &_symbols_processed);
4351 Atomic::add(symbols_removed, &_symbols_removed);
4352 }
4353 }
4354
4355 size_t strings_processed() const { return (size_t)_strings_processed; }
4356 size_t strings_removed() const { return (size_t)_strings_removed; }
4357
4358 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4359 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4360 };
4361
4362 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4363 private:
4364 static Monitor* _lock;
4365
4366 BoolObjectClosure* const _is_alive;
4367 const bool _unloading_occurred;
4368 const uint _num_workers;
4369
4370 // Variables used to claim nmethods.
4371 nmethod* _first_nmethod;
4372 volatile nmethod* _claimed_nmethod;
4373
4374 // The list of nmethods that need to be processed by the second pass.
4375 volatile nmethod* _postponed_list;
4376 volatile uint _num_entered_barrier;
4377
4378 public:
4379 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4380 _is_alive(is_alive),
4381 _unloading_occurred(unloading_occurred),
4382 _num_workers(num_workers),
4383 _first_nmethod(NULL),
4384 _claimed_nmethod(NULL),
4385 _postponed_list(NULL),
4386 _num_entered_barrier(0)
4387 {
4388 nmethod::increase_unloading_clock();
4389 // Get first alive nmethod
4390 NMethodIterator iter = NMethodIterator();
4391 if(iter.next_alive()) {
4392 _first_nmethod = iter.method();
4393 }
4394 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4395 }
4396
4397 ~G1CodeCacheUnloadingTask() {
4398 CodeCache::verify_clean_inline_caches();
4399
4400 CodeCache::set_needs_cache_clean(false);
4401 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4402
4403 CodeCache::verify_icholder_relocations();
4404 }
4405
4406 private:
4407 void add_to_postponed_list(nmethod* nm) {
4408 nmethod* old;
4409 do {
4410 old = (nmethod*)_postponed_list;
4411 nm->set_unloading_next(old);
4412 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4413 }
4414
4415 void clean_nmethod(nmethod* nm) {
4416 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4417
4418 if (postponed) {
4419 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4420 add_to_postponed_list(nm);
4421 }
4422
4423 // Mark that this thread has been cleaned/unloaded.
4424 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4425 nm->set_unloading_clock(nmethod::global_unloading_clock());
4426 }
4427
4428 void clean_nmethod_postponed(nmethod* nm) {
4429 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4430 }
4431
4432 static const int MaxClaimNmethods = 16;
4433
4434 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4435 nmethod* first;
4436 NMethodIterator last;
4437
4438 do {
4439 *num_claimed_nmethods = 0;
4440
4441 first = (nmethod*)_claimed_nmethod;
4442 last = NMethodIterator(first);
4443
4444 if (first != NULL) {
4445
4446 for (int i = 0; i < MaxClaimNmethods; i++) {
4447 if (!last.next_alive()) {
4448 break;
4449 }
4450 claimed_nmethods[i] = last.method();
4451 (*num_claimed_nmethods)++;
4452 }
4453 }
4454
4455 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4456 }
4457
4458 nmethod* claim_postponed_nmethod() {
4459 nmethod* claim;
4460 nmethod* next;
4461
4462 do {
4463 claim = (nmethod*)_postponed_list;
4464 if (claim == NULL) {
4465 return NULL;
4466 }
4467
4468 next = claim->unloading_next();
4469
4470 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4471
4472 return claim;
4473 }
4474
4475 public:
4476 // Mark that we're done with the first pass of nmethod cleaning.
4477 void barrier_mark(uint worker_id) {
4478 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4479 _num_entered_barrier++;
4480 if (_num_entered_barrier == _num_workers) {
4481 ml.notify_all();
4482 }
4483 }
4484
4485 // See if we have to wait for the other workers to
4486 // finish their first-pass nmethod cleaning work.
4487 void barrier_wait(uint worker_id) {
4488 if (_num_entered_barrier < _num_workers) {
4489 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4490 while (_num_entered_barrier < _num_workers) {
4491 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4492 }
4493 }
4494 }
4495
4496 // Cleaning and unloading of nmethods. Some work has to be postponed
4497 // to the second pass, when we know which nmethods survive.
4498 void work_first_pass(uint worker_id) {
4499 // The first nmethods is claimed by the first worker.
4500 if (worker_id == 0 && _first_nmethod != NULL) {
4501 clean_nmethod(_first_nmethod);
4502 _first_nmethod = NULL;
4503 }
4504
4505 int num_claimed_nmethods;
4506 nmethod* claimed_nmethods[MaxClaimNmethods];
4507
4508 while (true) {
4509 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4510
4511 if (num_claimed_nmethods == 0) {
4512 break;
4513 }
4514
4515 for (int i = 0; i < num_claimed_nmethods; i++) {
4516 clean_nmethod(claimed_nmethods[i]);
4517 }
4518 }
4519 }
4520
4521 void work_second_pass(uint worker_id) {
4522 nmethod* nm;
4523 // Take care of postponed nmethods.
4524 while ((nm = claim_postponed_nmethod()) != NULL) {
4525 clean_nmethod_postponed(nm);
4526 }
4527 }
4528 };
4529
4530 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4531
4532 class G1KlassCleaningTask : public StackObj {
4533 BoolObjectClosure* _is_alive;
4534 volatile jint _clean_klass_tree_claimed;
4535 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4536
4537 public:
4538 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4539 _is_alive(is_alive),
4540 _clean_klass_tree_claimed(0),
4541 _klass_iterator() {
4542 }
4543
4544 private:
4545 bool claim_clean_klass_tree_task() {
4546 if (_clean_klass_tree_claimed) {
4547 return false;
4548 }
4549
4550 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4551 }
4552
4553 InstanceKlass* claim_next_klass() {
4554 Klass* klass;
4555 do {
4556 klass =_klass_iterator.next_klass();
4557 } while (klass != NULL && !klass->is_instance_klass());
4558
4559 // this can be null so don't call InstanceKlass::cast
4560 return static_cast<InstanceKlass*>(klass);
4561 }
4562
4563 public:
4564
4565 void clean_klass(InstanceKlass* ik) {
4566 ik->clean_weak_instanceklass_links(_is_alive);
4567 }
4568
4569 void work() {
4570 ResourceMark rm;
4571
4572 // One worker will clean the subklass/sibling klass tree.
4573 if (claim_clean_klass_tree_task()) {
4574 Klass::clean_subklass_tree(_is_alive);
4575 }
4576
4577 // All workers will help cleaning the classes,
4578 InstanceKlass* klass;
4579 while ((klass = claim_next_klass()) != NULL) {
4580 clean_klass(klass);
4581 }
4582 }
4583 };
4584
4585 // To minimize the remark pause times, the tasks below are done in parallel.
4586 class G1ParallelCleaningTask : public AbstractGangTask {
4587 private:
4588 G1StringSymbolTableUnlinkTask _string_symbol_task;
4589 G1CodeCacheUnloadingTask _code_cache_task;
4590 G1KlassCleaningTask _klass_cleaning_task;
4591
4592 public:
4593 // The constructor is run in the VMThread.
4594 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4595 AbstractGangTask("Parallel Cleaning"),
4596 _string_symbol_task(is_alive, process_strings, process_symbols),
4597 _code_cache_task(num_workers, is_alive, unloading_occurred),
4598 _klass_cleaning_task(is_alive) {
4599 }
4600
4601 // The parallel work done by all worker threads.
4602 void work(uint worker_id) {
4603 // Do first pass of code cache cleaning.
4604 _code_cache_task.work_first_pass(worker_id);
4605
4606 // Let the threads mark that the first pass is done.
4607 _code_cache_task.barrier_mark(worker_id);
4608
4609 // Clean the Strings and Symbols.
4610 _string_symbol_task.work(worker_id);
4611
4612 // Wait for all workers to finish the first code cache cleaning pass.
4613 _code_cache_task.barrier_wait(worker_id);
4614
4615 // Do the second code cache cleaning work, which realize on
4616 // the liveness information gathered during the first pass.
4617 _code_cache_task.work_second_pass(worker_id);
4618
4619 // Clean all klasses that were not unloaded.
4620 _klass_cleaning_task.work();
4621 }
4622 };
4623
4624
4625 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4626 bool process_strings,
4627 bool process_symbols,
4628 bool class_unloading_occurred) {
4629 uint n_workers = workers()->active_workers();
4630
4631 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4632 n_workers, class_unloading_occurred);
4633 workers()->run_task(&g1_unlink_task);
4634 }
4635
4636 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4637 bool process_strings, bool process_symbols) {
4638 {
4639 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4640 workers()->run_task(&g1_unlink_task);
4641 }
4642
4643 if (G1StringDedup::is_enabled()) {
4644 G1StringDedup::unlink(is_alive);
4645 }
4646 }
4647
4648 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4649 private:
4650 DirtyCardQueueSet* _queue;
4651 public:
4652 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4653
4654 virtual void work(uint worker_id) {
4655 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4656 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4657
4658 RedirtyLoggedCardTableEntryClosure cl;
4659 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4660
4661 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4662 }
4663 };
4664
4665 void G1CollectedHeap::redirty_logged_cards() {
4666 double redirty_logged_cards_start = os::elapsedTime();
4667
4668 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4669 dirty_card_queue_set().reset_for_par_iteration();
4670 workers()->run_task(&redirty_task);
4671
4672 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4673 dcq.merge_bufferlists(&dirty_card_queue_set());
4674 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4675
4676 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4677 }
4678
4679 // Weak Reference Processing support
4680
4681 // An always "is_alive" closure that is used to preserve referents.
4682 // If the object is non-null then it's alive. Used in the preservation
4683 // of referent objects that are pointed to by reference objects
4684 // discovered by the CM ref processor.
4685 class G1AlwaysAliveClosure: public BoolObjectClosure {
4686 G1CollectedHeap* _g1;
4687 public:
4688 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4689 bool do_object_b(oop p) {
4690 if (p != NULL) {
4691 return true;
4692 }
4693 return false;
4694 }
4695 };
4696
4697 bool G1STWIsAliveClosure::do_object_b(oop p) {
4698 // An object is reachable if it is outside the collection set,
4699 // or is inside and copied.
4700 return !_g1->is_in_cset(p) || p->is_forwarded();
4701 }
4702
4703 // Non Copying Keep Alive closure
4704 class G1KeepAliveClosure: public OopClosure {
4705 G1CollectedHeap* _g1;
4706 public:
4707 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4708 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4709 void do_oop(oop* p) {
4710 oop obj = *p;
4711 assert(obj != NULL, "the caller should have filtered out NULL values");
4712
4713 const InCSetState cset_state = _g1->in_cset_state(obj);
4714 if (!cset_state.is_in_cset_or_humongous()) {
4715 return;
4716 }
4717 if (cset_state.is_in_cset()) {
4718 assert( obj->is_forwarded(), "invariant" );
4719 *p = obj->forwardee();
4720 } else {
4721 assert(!obj->is_forwarded(), "invariant" );
4722 assert(cset_state.is_humongous(),
4723 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4724 _g1->set_humongous_is_live(obj);
4725 }
4726 }
4727 };
4728
4729 // Copying Keep Alive closure - can be called from both
4730 // serial and parallel code as long as different worker
4731 // threads utilize different G1ParScanThreadState instances
4732 // and different queues.
4733
4734 class G1CopyingKeepAliveClosure: public OopClosure {
4735 G1CollectedHeap* _g1h;
4736 OopClosure* _copy_non_heap_obj_cl;
4737 G1ParScanThreadState* _par_scan_state;
4738
4739 public:
4740 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4741 OopClosure* non_heap_obj_cl,
4742 G1ParScanThreadState* pss):
4743 _g1h(g1h),
4744 _copy_non_heap_obj_cl(non_heap_obj_cl),
4745 _par_scan_state(pss)
4746 {}
4747
4748 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4749 virtual void do_oop( oop* p) { do_oop_work(p); }
4750
4751 template <class T> void do_oop_work(T* p) {
4752 oop obj = oopDesc::load_decode_heap_oop(p);
4753
4754 if (_g1h->is_in_cset_or_humongous(obj)) {
4755 // If the referent object has been forwarded (either copied
4756 // to a new location or to itself in the event of an
4757 // evacuation failure) then we need to update the reference
4758 // field and, if both reference and referent are in the G1
4759 // heap, update the RSet for the referent.
4760 //
4761 // If the referent has not been forwarded then we have to keep
4762 // it alive by policy. Therefore we have copy the referent.
4763 //
4764 // If the reference field is in the G1 heap then we can push
4765 // on the PSS queue. When the queue is drained (after each
4766 // phase of reference processing) the object and it's followers
4767 // will be copied, the reference field set to point to the
4768 // new location, and the RSet updated. Otherwise we need to
4769 // use the the non-heap or metadata closures directly to copy
4770 // the referent object and update the pointer, while avoiding
4771 // updating the RSet.
4772
4773 if (_g1h->is_in_g1_reserved(p)) {
4774 _par_scan_state->push_on_queue(p);
4775 } else {
4776 assert(!Metaspace::contains((const void*)p),
4777 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4778 _copy_non_heap_obj_cl->do_oop(p);
4779 }
4780 }
4781 }
4782 };
4783
4784 // Serial drain queue closure. Called as the 'complete_gc'
4785 // closure for each discovered list in some of the
4786 // reference processing phases.
4787
4788 class G1STWDrainQueueClosure: public VoidClosure {
4789 protected:
4790 G1CollectedHeap* _g1h;
4791 G1ParScanThreadState* _par_scan_state;
4792
4793 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4794
4795 public:
4796 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4797 _g1h(g1h),
4798 _par_scan_state(pss)
4799 { }
4800
4801 void do_void() {
4802 G1ParScanThreadState* const pss = par_scan_state();
4803 pss->trim_queue();
4804 }
4805 };
4806
4807 // Parallel Reference Processing closures
4808
4809 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4810 // processing during G1 evacuation pauses.
4811
4812 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4813 private:
4814 G1CollectedHeap* _g1h;
4815 G1ParScanThreadStateSet* _pss;
4816 RefToScanQueueSet* _queues;
4817 WorkGang* _workers;
4818 uint _active_workers;
4819
4820 public:
4821 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4822 G1ParScanThreadStateSet* per_thread_states,
4823 WorkGang* workers,
4824 RefToScanQueueSet *task_queues,
4825 uint n_workers) :
4826 _g1h(g1h),
4827 _pss(per_thread_states),
4828 _queues(task_queues),
4829 _workers(workers),
4830 _active_workers(n_workers)
4831 {
4832 assert(n_workers > 0, "shouldn't call this otherwise");
4833 }
4834
4835 // Executes the given task using concurrent marking worker threads.
4836 virtual void execute(ProcessTask& task);
4837 virtual void execute(EnqueueTask& task);
4838 };
4839
4840 // Gang task for possibly parallel reference processing
4841
4842 class G1STWRefProcTaskProxy: public AbstractGangTask {
4843 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4844 ProcessTask& _proc_task;
4845 G1CollectedHeap* _g1h;
4846 G1ParScanThreadStateSet* _pss;
4847 RefToScanQueueSet* _task_queues;
4848 ParallelTaskTerminator* _terminator;
4849
4850 public:
4851 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4852 G1CollectedHeap* g1h,
4853 G1ParScanThreadStateSet* per_thread_states,
4854 RefToScanQueueSet *task_queues,
4855 ParallelTaskTerminator* terminator) :
4856 AbstractGangTask("Process reference objects in parallel"),
4857 _proc_task(proc_task),
4858 _g1h(g1h),
4859 _pss(per_thread_states),
4860 _task_queues(task_queues),
4861 _terminator(terminator)
4862 {}
4863
4864 virtual void work(uint worker_id) {
4865 // The reference processing task executed by a single worker.
4866 ResourceMark rm;
4867 HandleMark hm;
4868
4869 G1STWIsAliveClosure is_alive(_g1h);
4870
4871 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4872 pss->set_ref_processor(NULL);
4873
4874 // Keep alive closure.
4875 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4876
4877 // Complete GC closure
4878 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4879
4880 // Call the reference processing task's work routine.
4881 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4882
4883 // Note we cannot assert that the refs array is empty here as not all
4884 // of the processing tasks (specifically phase2 - pp2_work) execute
4885 // the complete_gc closure (which ordinarily would drain the queue) so
4886 // the queue may not be empty.
4887 }
4888 };
4889
4890 // Driver routine for parallel reference processing.
4891 // Creates an instance of the ref processing gang
4892 // task and has the worker threads execute it.
4893 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4894 assert(_workers != NULL, "Need parallel worker threads.");
4895
4896 ParallelTaskTerminator terminator(_active_workers, _queues);
4897 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4898
4899 _workers->run_task(&proc_task_proxy);
4900 }
4901
4902 // Gang task for parallel reference enqueueing.
4903
4904 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4905 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4906 EnqueueTask& _enq_task;
4907
4908 public:
4909 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4910 AbstractGangTask("Enqueue reference objects in parallel"),
4911 _enq_task(enq_task)
4912 { }
4913
4914 virtual void work(uint worker_id) {
4915 _enq_task.work(worker_id);
4916 }
4917 };
4918
4919 // Driver routine for parallel reference enqueueing.
4920 // Creates an instance of the ref enqueueing gang
4921 // task and has the worker threads execute it.
4922
4923 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4924 assert(_workers != NULL, "Need parallel worker threads.");
4925
4926 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4927
4928 _workers->run_task(&enq_task_proxy);
4929 }
4930
4931 // End of weak reference support closures
4932
4933 // Abstract task used to preserve (i.e. copy) any referent objects
4934 // that are in the collection set and are pointed to by reference
4935 // objects discovered by the CM ref processor.
4936
4937 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4938 protected:
4939 G1CollectedHeap* _g1h;
4940 G1ParScanThreadStateSet* _pss;
4941 RefToScanQueueSet* _queues;
4942 ParallelTaskTerminator _terminator;
4943 uint _n_workers;
4944
4945 public:
4946 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4947 AbstractGangTask("ParPreserveCMReferents"),
4948 _g1h(g1h),
4949 _pss(per_thread_states),
4950 _queues(task_queues),
4951 _terminator(workers, _queues),
4952 _n_workers(workers)
4953 { }
4954
4955 void work(uint worker_id) {
4956 ResourceMark rm;
4957 HandleMark hm;
4958
4959 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4960 pss->set_ref_processor(NULL);
4961 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4962
4963 // Is alive closure
4964 G1AlwaysAliveClosure always_alive(_g1h);
4965
4966 // Copying keep alive closure. Applied to referent objects that need
4967 // to be copied.
4968 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4969
4970 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4971
4972 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4973 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4974
4975 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4976 // So this must be true - but assert just in case someone decides to
4977 // change the worker ids.
4978 assert(worker_id < limit, "sanity");
4979 assert(!rp->discovery_is_atomic(), "check this code");
4980
4981 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4982 for (uint idx = worker_id; idx < limit; idx += stride) {
4983 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4984
4985 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4986 while (iter.has_next()) {
4987 // Since discovery is not atomic for the CM ref processor, we
4988 // can see some null referent objects.
4989 iter.load_ptrs(DEBUG_ONLY(true));
4990 oop ref = iter.obj();
4991
4992 // This will filter nulls.
4993 if (iter.is_referent_alive()) {
4994 iter.make_referent_alive();
4995 }
4996 iter.move_to_next();
4997 }
4998 }
4999
5000 // Drain the queue - which may cause stealing
5001 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5002 drain_queue.do_void();
5003 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5004 assert(pss->queue_is_empty(), "should be");
5005 }
5006 };
5007
5008 // Weak Reference processing during an evacuation pause (part 1).
5009 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5010 double ref_proc_start = os::elapsedTime();
5011
5012 ReferenceProcessor* rp = _ref_processor_stw;
5013 assert(rp->discovery_enabled(), "should have been enabled");
5014
5015 // Any reference objects, in the collection set, that were 'discovered'
5016 // by the CM ref processor should have already been copied (either by
5017 // applying the external root copy closure to the discovered lists, or
5018 // by following an RSet entry).
5019 //
5020 // But some of the referents, that are in the collection set, that these
5021 // reference objects point to may not have been copied: the STW ref
5022 // processor would have seen that the reference object had already
5023 // been 'discovered' and would have skipped discovering the reference,
5024 // but would not have treated the reference object as a regular oop.
5025 // As a result the copy closure would not have been applied to the
5026 // referent object.
5027 //
5028 // We need to explicitly copy these referent objects - the references
5029 // will be processed at the end of remarking.
5030 //
5031 // We also need to do this copying before we process the reference
5032 // objects discovered by the STW ref processor in case one of these
5033 // referents points to another object which is also referenced by an
5034 // object discovered by the STW ref processor.
5035
5036 uint no_of_gc_workers = workers()->active_workers();
5037
5038 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5039 per_thread_states,
5040 no_of_gc_workers,
5041 _task_queues);
5042
5043 workers()->run_task(&keep_cm_referents);
5044
5045 // Closure to test whether a referent is alive.
5046 G1STWIsAliveClosure is_alive(this);
5047
5048 // Even when parallel reference processing is enabled, the processing
5049 // of JNI refs is serial and performed serially by the current thread
5050 // rather than by a worker. The following PSS will be used for processing
5051 // JNI refs.
5052
5053 // Use only a single queue for this PSS.
5054 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5055 pss->set_ref_processor(NULL);
5056 assert(pss->queue_is_empty(), "pre-condition");
5057
5058 // Keep alive closure.
5059 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5060
5061 // Serial Complete GC closure
5062 G1STWDrainQueueClosure drain_queue(this, pss);
5063
5064 // Setup the soft refs policy...
5065 rp->setup_policy(false);
5066
5067 ReferenceProcessorStats stats;
5068 if (!rp->processing_is_mt()) {
5069 // Serial reference processing...
5070 stats = rp->process_discovered_references(&is_alive,
5071 &keep_alive,
5072 &drain_queue,
5073 NULL,
5074 _gc_timer_stw);
5075 } else {
5076 // Parallel reference processing
5077 assert(rp->num_q() == no_of_gc_workers, "sanity");
5078 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5079
5080 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5081 stats = rp->process_discovered_references(&is_alive,
5082 &keep_alive,
5083 &drain_queue,
5084 &par_task_executor,
5085 _gc_timer_stw);
5086 }
5087
5088 _gc_tracer_stw->report_gc_reference_stats(stats);
5089
5090 // We have completed copying any necessary live referent objects.
5091 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5092
5093 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5094 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5095 }
5096
5097 // Weak Reference processing during an evacuation pause (part 2).
5098 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5099 double ref_enq_start = os::elapsedTime();
5100
5101 ReferenceProcessor* rp = _ref_processor_stw;
5102 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5103
5104 // Now enqueue any remaining on the discovered lists on to
5105 // the pending list.
5106 if (!rp->processing_is_mt()) {
5107 // Serial reference processing...
5108 rp->enqueue_discovered_references();
5109 } else {
5110 // Parallel reference enqueueing
5111
5112 uint n_workers = workers()->active_workers();
5113
5114 assert(rp->num_q() == n_workers, "sanity");
5115 assert(n_workers <= rp->max_num_q(), "sanity");
5116
5117 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5118 rp->enqueue_discovered_references(&par_task_executor);
5119 }
5120
5121 rp->verify_no_references_recorded();
5122 assert(!rp->discovery_enabled(), "should have been disabled");
5123
5124 // FIXME
5125 // CM's reference processing also cleans up the string and symbol tables.
5126 // Should we do that here also? We could, but it is a serial operation
5127 // and could significantly increase the pause time.
5128
5129 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5130 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5131 }
5132
5133 void G1CollectedHeap::pre_evacuate_collection_set() {
5134 _expand_heap_after_alloc_failure = true;
5135 _evacuation_failed = false;
5136
5137 // Disable the hot card cache.
5138 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5139 hot_card_cache->reset_hot_cache_claimed_index();
5140 hot_card_cache->set_use_cache(false);
5141
5142 }
5143
5144 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5145 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5146
5147 // Should G1EvacuationFailureALot be in effect for this GC?
5148 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5149
5150 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5151 double start_par_time_sec = os::elapsedTime();
5152 double end_par_time_sec;
5153
5154 {
5155 const uint n_workers = workers()->active_workers();
5156 G1RootProcessor root_processor(this, n_workers);
5157 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5158 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5159 if (collector_state()->during_initial_mark_pause()) {
5160 ClassLoaderDataGraph::clear_claimed_marks();
5161 }
5162
5163 // The individual threads will set their evac-failure closures.
5164 if (PrintTerminationStats) {
5165 print_termination_stats_hdr(gclog_or_tty);
5166 }
5167
5168 workers()->run_task(&g1_par_task);
5169 end_par_time_sec = os::elapsedTime();
5170
5171 // Closing the inner scope will execute the destructor
5172 // for the G1RootProcessor object. We record the current
5173 // elapsed time before closing the scope so that time
5174 // taken for the destructor is NOT included in the
5175 // reported parallel time.
5176 }
5177
5178 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5179
5180 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5181 phase_times->record_par_time(par_time_ms);
5182
5183 double code_root_fixup_time_ms =
5184 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5185 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5186
5187 // Process any discovered reference objects - we have
5188 // to do this _before_ we retire the GC alloc regions
5189 // as we may have to copy some 'reachable' referent
5190 // objects (and their reachable sub-graphs) that were
5191 // not copied during the pause.
5192 process_discovered_references(per_thread_states);
5193
5194 if (G1StringDedup::is_enabled()) {
5195 double fixup_start = os::elapsedTime();
5196
5197 G1STWIsAliveClosure is_alive(this);
5198 G1KeepAliveClosure keep_alive(this);
5199 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5200
5201 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5202 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5203 }
5204
5205 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5206
5207 if (evacuation_failed()) {
5208 remove_self_forwarding_pointers();
5209
5210 // Reset the G1EvacuationFailureALot counters and flags
5211 // Note: the values are reset only when an actual
5212 // evacuation failure occurs.
5213 NOT_PRODUCT(reset_evacuation_should_fail();)
5214 }
5215
5216 // Enqueue any remaining references remaining on the STW
5217 // reference processor's discovered lists. We need to do
5218 // this after the card table is cleaned (and verified) as
5219 // the act of enqueueing entries on to the pending list
5220 // will log these updates (and dirty their associated
5221 // cards). We need these updates logged to update any
5222 // RSets.
5223 enqueue_discovered_references(per_thread_states);
5224 }
5225
5226 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5227 _allocator->release_gc_alloc_regions(evacuation_info);
5228
5229 per_thread_states->flush();
5230
5231 record_obj_copy_mem_stats();
5232
5233 _survivor_evac_stats.adjust_desired_plab_sz();
5234 _old_evac_stats.adjust_desired_plab_sz();
5235
5236 // Reset and re-enable the hot card cache.
5237 // Note the counts for the cards in the regions in the
5238 // collection set are reset when the collection set is freed.
5239 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5240 hot_card_cache->reset_hot_cache();
5241 hot_card_cache->set_use_cache(true);
5242
5243 purge_code_root_memory();
5244
5245 redirty_logged_cards();
5246 #if defined(COMPILER2) || INCLUDE_JVMCI
5247 DerivedPointerTable::update_pointers();
5248 #endif
5249 }
5250
5251 void G1CollectedHeap::record_obj_copy_mem_stats() {
5252 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5253 create_g1_evac_summary(&_old_evac_stats));
5254 }
5255
5256 void G1CollectedHeap::free_region(HeapRegion* hr,
5257 FreeRegionList* free_list,
5258 bool par,
5259 bool locked) {
5260 assert(!hr->is_free(), "the region should not be free");
5261 assert(!hr->is_empty(), "the region should not be empty");
5262 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5263 assert(free_list != NULL, "pre-condition");
5264
5265 if (G1VerifyBitmaps) {
5266 MemRegion mr(hr->bottom(), hr->end());
5267 concurrent_mark()->clearRangePrevBitmap(mr);
5268 }
5269
5270 // Clear the card counts for this region.
5271 // Note: we only need to do this if the region is not young
5272 // (since we don't refine cards in young regions).
5273 if (!hr->is_young()) {
5274 _cg1r->hot_card_cache()->reset_card_counts(hr);
5275 }
5276 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5277 free_list->add_ordered(hr);
5278 }
5279
5280 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5281 FreeRegionList* free_list,
5282 bool par) {
5283 assert(hr->is_humongous(), "this is only for humongous regions");
5284 assert(free_list != NULL, "pre-condition");
5285 hr->clear_humongous();
5286 free_region(hr, free_list, par);
5287 }
5288
5289 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5290 const HeapRegionSetCount& humongous_regions_removed) {
5291 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5292 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5293 _old_set.bulk_remove(old_regions_removed);
5294 _humongous_set.bulk_remove(humongous_regions_removed);
5295 }
5296
5297 }
5298
5299 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5300 assert(list != NULL, "list can't be null");
5301 if (!list->is_empty()) {
5302 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5303 _hrm.insert_list_into_free_list(list);
5304 }
5305 }
5306
5307 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5308 decrease_used(bytes);
5309 }
5310
5311 class G1ParCleanupCTTask : public AbstractGangTask {
5312 G1SATBCardTableModRefBS* _ct_bs;
5313 G1CollectedHeap* _g1h;
5314 HeapRegion* volatile _su_head;
5315 public:
5316 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5317 G1CollectedHeap* g1h) :
5318 AbstractGangTask("G1 Par Cleanup CT Task"),
5319 _ct_bs(ct_bs), _g1h(g1h) { }
5320
5321 void work(uint worker_id) {
5322 HeapRegion* r;
5323 while (r = _g1h->pop_dirty_cards_region()) {
5324 clear_cards(r);
5325 }
5326 }
5327
5328 void clear_cards(HeapRegion* r) {
5329 // Cards of the survivors should have already been dirtied.
5330 if (!r->is_survivor()) {
5331 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5332 }
5333 }
5334 };
5335
5336 #ifndef PRODUCT
5337 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5338 G1CollectedHeap* _g1h;
5339 G1SATBCardTableModRefBS* _ct_bs;
5340 public:
5341 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5342 : _g1h(g1h), _ct_bs(ct_bs) { }
5343 virtual bool doHeapRegion(HeapRegion* r) {
5344 if (r->is_survivor()) {
5345 _g1h->verify_dirty_region(r);
5346 } else {
5347 _g1h->verify_not_dirty_region(r);
5348 }
5349 return false;
5350 }
5351 };
5352
5353 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5354 // All of the region should be clean.
5355 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5356 MemRegion mr(hr->bottom(), hr->end());
5357 ct_bs->verify_not_dirty_region(mr);
5358 }
5359
5360 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5361 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5362 // dirty allocated blocks as they allocate them. The thread that
5363 // retires each region and replaces it with a new one will do a
5364 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5365 // not dirty that area (one less thing to have to do while holding
5366 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5367 // is dirty.
5368 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5369 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5370 if (hr->is_young()) {
5371 ct_bs->verify_g1_young_region(mr);
5372 } else {
5373 ct_bs->verify_dirty_region(mr);
5374 }
5375 }
5376
5377 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5378 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5379 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5380 verify_dirty_region(hr);
5381 }
5382 }
5383
5384 void G1CollectedHeap::verify_dirty_young_regions() {
5385 verify_dirty_young_list(_young_list->first_region());
5386 }
5387
5388 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5389 HeapWord* tams, HeapWord* end) {
5390 guarantee(tams <= end,
5391 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5392 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5393 if (result < end) {
5394 gclog_or_tty->cr();
5395 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5396 bitmap_name, p2i(result));
5397 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5398 bitmap_name, p2i(tams), p2i(end));
5399 return false;
5400 }
5401 return true;
5402 }
5403
5404 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5405 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5406 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5407
5408 HeapWord* bottom = hr->bottom();
5409 HeapWord* ptams = hr->prev_top_at_mark_start();
5410 HeapWord* ntams = hr->next_top_at_mark_start();
5411 HeapWord* end = hr->end();
5412
5413 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5414
5415 bool res_n = true;
5416 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5417 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5418 // if we happen to be in that state.
5419 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5420 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5421 }
5422 if (!res_p || !res_n) {
5423 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5424 HR_FORMAT_PARAMS(hr));
5425 gclog_or_tty->print_cr("#### Caller: %s", caller);
5426 return false;
5427 }
5428 return true;
5429 }
5430
5431 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5432 if (!G1VerifyBitmaps) return;
5433
5434 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5435 }
5436
5437 class G1VerifyBitmapClosure : public HeapRegionClosure {
5438 private:
5439 const char* _caller;
5440 G1CollectedHeap* _g1h;
5441 bool _failures;
5442
5443 public:
5444 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5445 _caller(caller), _g1h(g1h), _failures(false) { }
5446
5447 bool failures() { return _failures; }
5448
5449 virtual bool doHeapRegion(HeapRegion* hr) {
5450 bool result = _g1h->verify_bitmaps(_caller, hr);
5451 if (!result) {
5452 _failures = true;
5453 }
5454 return false;
5455 }
5456 };
5457
5458 void G1CollectedHeap::check_bitmaps(const char* caller) {
5459 if (!G1VerifyBitmaps) return;
5460
5461 G1VerifyBitmapClosure cl(caller, this);
5462 heap_region_iterate(&cl);
5463 guarantee(!cl.failures(), "bitmap verification");
5464 }
5465
5466 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5467 private:
5468 bool _failures;
5469 public:
5470 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5471
5472 virtual bool doHeapRegion(HeapRegion* hr) {
5473 uint i = hr->hrm_index();
5474 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5475 if (hr->is_humongous()) {
5476 if (hr->in_collection_set()) {
5477 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5478 _failures = true;
5479 return true;
5480 }
5481 if (cset_state.is_in_cset()) {
5482 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5483 _failures = true;
5484 return true;
5485 }
5486 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5487 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5488 _failures = true;
5489 return true;
5490 }
5491 } else {
5492 if (cset_state.is_humongous()) {
5493 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5494 _failures = true;
5495 return true;
5496 }
5497 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5498 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5499 hr->in_collection_set(), cset_state.value(), i);
5500 _failures = true;
5501 return true;
5502 }
5503 if (cset_state.is_in_cset()) {
5504 if (hr->is_young() != (cset_state.is_young())) {
5505 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5506 hr->is_young(), cset_state.value(), i);
5507 _failures = true;
5508 return true;
5509 }
5510 if (hr->is_old() != (cset_state.is_old())) {
5511 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5512 hr->is_old(), cset_state.value(), i);
5513 _failures = true;
5514 return true;
5515 }
5516 }
5517 }
5518 return false;
5519 }
5520
5521 bool failures() const { return _failures; }
5522 };
5523
5524 bool G1CollectedHeap::check_cset_fast_test() {
5525 G1CheckCSetFastTableClosure cl;
5526 _hrm.iterate(&cl);
5527 return !cl.failures();
5528 }
5529 #endif // PRODUCT
5530
5531 void G1CollectedHeap::cleanUpCardTable() {
5532 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5533 double start = os::elapsedTime();
5534
5535 {
5536 // Iterate over the dirty cards region list.
5537 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5538
5539 workers()->run_task(&cleanup_task);
5540 #ifndef PRODUCT
5541 if (G1VerifyCTCleanup || VerifyAfterGC) {
5542 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5543 heap_region_iterate(&cleanup_verifier);
5544 }
5545 #endif
5546 }
5547
5548 double elapsed = os::elapsedTime() - start;
5549 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5550 }
5551
5552 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5553 size_t pre_used = 0;
5554 FreeRegionList local_free_list("Local List for CSet Freeing");
5555
5556 double young_time_ms = 0.0;
5557 double non_young_time_ms = 0.0;
5558
5559 // Since the collection set is a superset of the the young list,
5560 // all we need to do to clear the young list is clear its
5561 // head and length, and unlink any young regions in the code below
5562 _young_list->clear();
5563
5564 G1CollectorPolicy* policy = g1_policy();
5565
5566 double start_sec = os::elapsedTime();
5567 bool non_young = true;
5568
5569 HeapRegion* cur = cs_head;
5570 int age_bound = -1;
5571 size_t rs_lengths = 0;
5572
5573 while (cur != NULL) {
5574 assert(!is_on_master_free_list(cur), "sanity");
5575 if (non_young) {
5576 if (cur->is_young()) {
5577 double end_sec = os::elapsedTime();
5578 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5579 non_young_time_ms += elapsed_ms;
5580
5581 start_sec = os::elapsedTime();
5582 non_young = false;
5583 }
5584 } else {
5585 if (!cur->is_young()) {
5586 double end_sec = os::elapsedTime();
5587 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5588 young_time_ms += elapsed_ms;
5589
5590 start_sec = os::elapsedTime();
5591 non_young = true;
5592 }
5593 }
5594
5595 rs_lengths += cur->rem_set()->occupied_locked();
5596
5597 HeapRegion* next = cur->next_in_collection_set();
5598 assert(cur->in_collection_set(), "bad CS");
5599 cur->set_next_in_collection_set(NULL);
5600 clear_in_cset(cur);
5601
5602 if (cur->is_young()) {
5603 int index = cur->young_index_in_cset();
5604 assert(index != -1, "invariant");
5605 assert((uint) index < policy->young_cset_region_length(), "invariant");
5606 size_t words_survived = surviving_young_words[index];
5607 cur->record_surv_words_in_group(words_survived);
5608
5609 // At this point the we have 'popped' cur from the collection set
5610 // (linked via next_in_collection_set()) but it is still in the
5611 // young list (linked via next_young_region()). Clear the
5612 // _next_young_region field.
5613 cur->set_next_young_region(NULL);
5614 } else {
5615 int index = cur->young_index_in_cset();
5616 assert(index == -1, "invariant");
5617 }
5618
5619 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5620 (!cur->is_young() && cur->young_index_in_cset() == -1),
5621 "invariant" );
5622
5623 if (!cur->evacuation_failed()) {
5624 MemRegion used_mr = cur->used_region();
5625
5626 // And the region is empty.
5627 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5628 pre_used += cur->used();
5629 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5630 } else {
5631 cur->uninstall_surv_rate_group();
5632 if (cur->is_young()) {
5633 cur->set_young_index_in_cset(-1);
5634 }
5635 cur->set_evacuation_failed(false);
5636 // The region is now considered to be old.
5637 cur->set_old();
5638 // Do some allocation statistics accounting. Regions that failed evacuation
5639 // are always made old, so there is no need to update anything in the young
5640 // gen statistics, but we need to update old gen statistics.
5641 size_t used_words = cur->marked_bytes() / HeapWordSize;
5642 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5643 _old_set.add(cur);
5644 evacuation_info.increment_collectionset_used_after(cur->used());
5645 }
5646 cur = next;
5647 }
5648
5649 evacuation_info.set_regions_freed(local_free_list.length());
5650 policy->record_max_rs_lengths(rs_lengths);
5651 policy->cset_regions_freed();
5652
5653 double end_sec = os::elapsedTime();
5654 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5655
5656 if (non_young) {
5657 non_young_time_ms += elapsed_ms;
5658 } else {
5659 young_time_ms += elapsed_ms;
5660 }
5661
5662 prepend_to_freelist(&local_free_list);
5663 decrement_summary_bytes(pre_used);
5664 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5665 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5666 }
5667
5668 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5669 private:
5670 FreeRegionList* _free_region_list;
5671 HeapRegionSet* _proxy_set;
5672 HeapRegionSetCount _humongous_regions_removed;
5673 size_t _freed_bytes;
5674 public:
5675
5676 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5677 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5678 }
5679
5680 virtual bool doHeapRegion(HeapRegion* r) {
5681 if (!r->is_starts_humongous()) {
5682 return false;
5683 }
5684
5685 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5686
5687 oop obj = (oop)r->bottom();
5688 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5689
5690 // The following checks whether the humongous object is live are sufficient.
5691 // The main additional check (in addition to having a reference from the roots
5692 // or the young gen) is whether the humongous object has a remembered set entry.
5693 //
5694 // A humongous object cannot be live if there is no remembered set for it
5695 // because:
5696 // - there can be no references from within humongous starts regions referencing
5697 // the object because we never allocate other objects into them.
5698 // (I.e. there are no intra-region references that may be missed by the
5699 // remembered set)
5700 // - as soon there is a remembered set entry to the humongous starts region
5701 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5702 // until the end of a concurrent mark.
5703 //
5704 // It is not required to check whether the object has been found dead by marking
5705 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5706 // all objects allocated during that time are considered live.
5707 // SATB marking is even more conservative than the remembered set.
5708 // So if at this point in the collection there is no remembered set entry,
5709 // nobody has a reference to it.
5710 // At the start of collection we flush all refinement logs, and remembered sets
5711 // are completely up-to-date wrt to references to the humongous object.
5712 //
5713 // Other implementation considerations:
5714 // - never consider object arrays at this time because they would pose
5715 // considerable effort for cleaning up the the remembered sets. This is
5716 // required because stale remembered sets might reference locations that
5717 // are currently allocated into.
5718 uint region_idx = r->hrm_index();
5719 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5720 !r->rem_set()->is_empty()) {
5721
5722 if (G1TraceEagerReclaimHumongousObjects) {
5723 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",
5724 region_idx,
5725 (size_t)obj->size() * HeapWordSize,
5726 p2i(r->bottom()),
5727 r->rem_set()->occupied(),
5728 r->rem_set()->strong_code_roots_list_length(),
5729 next_bitmap->isMarked(r->bottom()),
5730 g1h->is_humongous_reclaim_candidate(region_idx),
5731 obj->is_typeArray()
5732 );
5733 }
5734
5735 return false;
5736 }
5737
5738 guarantee(obj->is_typeArray(),
5739 "Only eagerly reclaiming type arrays is supported, but the object "
5740 PTR_FORMAT " is not.", p2i(r->bottom()));
5741
5742 if (G1TraceEagerReclaimHumongousObjects) {
5743 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",
5744 region_idx,
5745 (size_t)obj->size() * HeapWordSize,
5746 p2i(r->bottom()),
5747 r->rem_set()->occupied(),
5748 r->rem_set()->strong_code_roots_list_length(),
5749 next_bitmap->isMarked(r->bottom()),
5750 g1h->is_humongous_reclaim_candidate(region_idx),
5751 obj->is_typeArray()
5752 );
5753 }
5754 // Need to clear mark bit of the humongous object if already set.
5755 if (next_bitmap->isMarked(r->bottom())) {
5756 next_bitmap->clear(r->bottom());
5757 }
5758 do {
5759 HeapRegion* next = g1h->next_region_in_humongous(r);
5760 _freed_bytes += r->used();
5761 r->set_containing_set(NULL);
5762 _humongous_regions_removed.increment(1u, r->capacity());
5763 g1h->free_humongous_region(r, _free_region_list, false);
5764 r = next;
5765 } while (r != NULL);
5766
5767 return false;
5768 }
5769
5770 HeapRegionSetCount& humongous_free_count() {
5771 return _humongous_regions_removed;
5772 }
5773
5774 size_t bytes_freed() const {
5775 return _freed_bytes;
5776 }
5777
5778 size_t humongous_reclaimed() const {
5779 return _humongous_regions_removed.length();
5780 }
5781 };
5782
5783 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5784 assert_at_safepoint(true);
5785
5786 if (!G1EagerReclaimHumongousObjects ||
5787 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5788 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5789 return;
5790 }
5791
5792 double start_time = os::elapsedTime();
5793
5794 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5795
5796 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5797 heap_region_iterate(&cl);
5798
5799 HeapRegionSetCount empty_set;
5800 remove_from_old_sets(empty_set, cl.humongous_free_count());
5801
5802 G1HRPrinter* hrp = hr_printer();
5803 if (hrp->is_active()) {
5804 FreeRegionListIterator iter(&local_cleanup_list);
5805 while (iter.more_available()) {
5806 HeapRegion* hr = iter.get_next();
5807 hrp->cleanup(hr);
5808 }
5809 }
5810
5811 prepend_to_freelist(&local_cleanup_list);
5812 decrement_summary_bytes(cl.bytes_freed());
5813
5814 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5815 cl.humongous_reclaimed());
5816 }
5817
5818 // This routine is similar to the above but does not record
5819 // any policy statistics or update free lists; we are abandoning
5820 // the current incremental collection set in preparation of a
5821 // full collection. After the full GC we will start to build up
5822 // the incremental collection set again.
5823 // This is only called when we're doing a full collection
5824 // and is immediately followed by the tearing down of the young list.
5825
5826 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5827 HeapRegion* cur = cs_head;
5828
5829 while (cur != NULL) {
5830 HeapRegion* next = cur->next_in_collection_set();
5831 assert(cur->in_collection_set(), "bad CS");
5832 cur->set_next_in_collection_set(NULL);
5833 clear_in_cset(cur);
5834 cur->set_young_index_in_cset(-1);
5835 cur = next;
5836 }
5837 }
5838
5839 void G1CollectedHeap::set_free_regions_coming() {
5840 if (G1ConcRegionFreeingVerbose) {
5841 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5842 "setting free regions coming");
5843 }
5844
5845 assert(!free_regions_coming(), "pre-condition");
5846 _free_regions_coming = true;
5847 }
5848
5849 void G1CollectedHeap::reset_free_regions_coming() {
5850 assert(free_regions_coming(), "pre-condition");
5851
5852 {
5853 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5854 _free_regions_coming = false;
5855 SecondaryFreeList_lock->notify_all();
5856 }
5857
5858 if (G1ConcRegionFreeingVerbose) {
5859 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5860 "reset free regions coming");
5861 }
5862 }
5863
5864 void G1CollectedHeap::wait_while_free_regions_coming() {
5865 // Most of the time we won't have to wait, so let's do a quick test
5866 // first before we take the lock.
5867 if (!free_regions_coming()) {
5868 return;
5869 }
5870
5871 if (G1ConcRegionFreeingVerbose) {
5872 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5873 "waiting for free regions");
5874 }
5875
5876 {
5877 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5878 while (free_regions_coming()) {
5879 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5880 }
5881 }
5882
5883 if (G1ConcRegionFreeingVerbose) {
5884 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5885 "done waiting for free regions");
5886 }
5887 }
5888
5889 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5890 return _allocator->is_retained_old_region(hr);
5891 }
5892
5893 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5894 _young_list->push_region(hr);
5895 }
5896
5897 class NoYoungRegionsClosure: public HeapRegionClosure {
5898 private:
5899 bool _success;
5900 public:
5901 NoYoungRegionsClosure() : _success(true) { }
5902 bool doHeapRegion(HeapRegion* r) {
5903 if (r->is_young()) {
5904 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5905 p2i(r->bottom()), p2i(r->end()));
5906 _success = false;
5907 }
5908 return false;
5909 }
5910 bool success() { return _success; }
5911 };
5912
5913 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5914 bool ret = _young_list->check_list_empty(check_sample);
5915
5916 if (check_heap) {
5917 NoYoungRegionsClosure closure;
5918 heap_region_iterate(&closure);
5919 ret = ret && closure.success();
5920 }
5921
5922 return ret;
5923 }
5924
5925 class TearDownRegionSetsClosure : public HeapRegionClosure {
5926 private:
5927 HeapRegionSet *_old_set;
5928
5929 public:
5930 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5931
5932 bool doHeapRegion(HeapRegion* r) {
5933 if (r->is_old()) {
5934 _old_set->remove(r);
5935 } else {
5936 // We ignore free regions, we'll empty the free list afterwards.
5937 // We ignore young regions, we'll empty the young list afterwards.
5938 // We ignore humongous regions, we're not tearing down the
5939 // humongous regions set.
5940 assert(r->is_free() || r->is_young() || r->is_humongous(),
5941 "it cannot be another type");
5942 }
5943 return false;
5944 }
5945
5946 ~TearDownRegionSetsClosure() {
5947 assert(_old_set->is_empty(), "post-condition");
5948 }
5949 };
5950
5951 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5952 assert_at_safepoint(true /* should_be_vm_thread */);
5953
5954 if (!free_list_only) {
5955 TearDownRegionSetsClosure cl(&_old_set);
5956 heap_region_iterate(&cl);
5957
5958 // Note that emptying the _young_list is postponed and instead done as
5959 // the first step when rebuilding the regions sets again. The reason for
5960 // this is that during a full GC string deduplication needs to know if
5961 // a collected region was young or old when the full GC was initiated.
5962 }
5963 _hrm.remove_all_free_regions();
5964 }
5965
5966 void G1CollectedHeap::increase_used(size_t bytes) {
5967 _summary_bytes_used += bytes;
5968 }
5969
5970 void G1CollectedHeap::decrease_used(size_t bytes) {
5971 assert(_summary_bytes_used >= bytes,
5972 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5973 _summary_bytes_used, bytes);
5974 _summary_bytes_used -= bytes;
5975 }
5976
5977 void G1CollectedHeap::set_used(size_t bytes) {
5978 _summary_bytes_used = bytes;
5979 }
5980
5981 class RebuildRegionSetsClosure : public HeapRegionClosure {
5982 private:
5983 bool _free_list_only;
5984 HeapRegionSet* _old_set;
5985 HeapRegionManager* _hrm;
5986 size_t _total_used;
5987
5988 public:
5989 RebuildRegionSetsClosure(bool free_list_only,
5990 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5991 _free_list_only(free_list_only),
5992 _old_set(old_set), _hrm(hrm), _total_used(0) {
5993 assert(_hrm->num_free_regions() == 0, "pre-condition");
5994 if (!free_list_only) {
5995 assert(_old_set->is_empty(), "pre-condition");
5996 }
5997 }
5998
5999 bool doHeapRegion(HeapRegion* r) {
6000 if (r->is_empty()) {
6001 // Add free regions to the free list
6002 r->set_free();
6003 r->set_allocation_context(AllocationContext::system());
6004 _hrm->insert_into_free_list(r);
6005 } else if (!_free_list_only) {
6006 assert(!r->is_young(), "we should not come across young regions");
6007
6008 if (r->is_humongous()) {
6009 // We ignore humongous regions. We left the humongous set unchanged.
6010 } else {
6011 // Objects that were compacted would have ended up on regions
6012 // that were previously old or free. Archive regions (which are
6013 // old) will not have been touched.
6014 assert(r->is_free() || r->is_old(), "invariant");
6015 // We now consider them old, so register as such. Leave
6016 // archive regions set that way, however, while still adding
6017 // them to the old set.
6018 if (!r->is_archive()) {
6019 r->set_old();
6020 }
6021 _old_set->add(r);
6022 }
6023 _total_used += r->used();
6024 }
6025
6026 return false;
6027 }
6028
6029 size_t total_used() {
6030 return _total_used;
6031 }
6032 };
6033
6034 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6035 assert_at_safepoint(true /* should_be_vm_thread */);
6036
6037 if (!free_list_only) {
6038 _young_list->empty_list();
6039 }
6040
6041 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6042 heap_region_iterate(&cl);
6043
6044 if (!free_list_only) {
6045 set_used(cl.total_used());
6046 if (_archive_allocator != NULL) {
6047 _archive_allocator->clear_used();
6048 }
6049 }
6050 assert(used_unlocked() == recalculate_used(),
6051 "inconsistent used_unlocked(), "
6052 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6053 used_unlocked(), recalculate_used());
6054 }
6055
6056 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6057 _refine_cte_cl->set_concurrent(concurrent);
6058 }
6059
6060 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6061 HeapRegion* hr = heap_region_containing(p);
6062 return hr->is_in(p);
6063 }
6064
6065 // Methods for the mutator alloc region
6066
6067 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6068 bool force) {
6069 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6070 assert(!force || g1_policy()->can_expand_young_list(),
6071 "if force is true we should be able to expand the young list");
6072 bool young_list_full = g1_policy()->is_young_list_full();
6073 if (force || !young_list_full) {
6074 HeapRegion* new_alloc_region = new_region(word_size,
6075 false /* is_old */,
6076 false /* do_expand */);
6077 if (new_alloc_region != NULL) {
6078 set_region_short_lived_locked(new_alloc_region);
6079 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6080 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6081 return new_alloc_region;
6082 }
6083 }
6084 return NULL;
6085 }
6086
6087 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6088 size_t allocated_bytes) {
6089 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6090 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6091
6092 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6093 increase_used(allocated_bytes);
6094 _hr_printer.retire(alloc_region);
6095 // We update the eden sizes here, when the region is retired,
6096 // instead of when it's allocated, since this is the point that its
6097 // used space has been recored in _summary_bytes_used.
6098 g1mm()->update_eden_size();
6099 }
6100
6101 // Methods for the GC alloc regions
6102
6103 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6104 uint count,
6105 InCSetState dest) {
6106 assert(FreeList_lock->owned_by_self(), "pre-condition");
6107
6108 if (count < g1_policy()->max_regions(dest)) {
6109 const bool is_survivor = (dest.is_young());
6110 HeapRegion* new_alloc_region = new_region(word_size,
6111 !is_survivor,
6112 true /* do_expand */);
6113 if (new_alloc_region != NULL) {
6114 // We really only need to do this for old regions given that we
6115 // should never scan survivors. But it doesn't hurt to do it
6116 // for survivors too.
6117 new_alloc_region->record_timestamp();
6118 if (is_survivor) {
6119 new_alloc_region->set_survivor();
6120 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6121 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6122 } else {
6123 new_alloc_region->set_old();
6124 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6125 check_bitmaps("Old Region Allocation", new_alloc_region);
6126 }
6127 bool during_im = collector_state()->during_initial_mark_pause();
6128 new_alloc_region->note_start_of_copying(during_im);
6129 return new_alloc_region;
6130 }
6131 }
6132 return NULL;
6133 }
6134
6135 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6136 size_t allocated_bytes,
6137 InCSetState dest) {
6138 bool during_im = collector_state()->during_initial_mark_pause();
6139 alloc_region->note_end_of_copying(during_im);
6140 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6141 if (dest.is_young()) {
6142 young_list()->add_survivor_region(alloc_region);
6143 } else {
6144 _old_set.add(alloc_region);
6145 }
6146 _hr_printer.retire(alloc_region);
6147 }
6148
6149 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6150 bool expanded = false;
6151 uint index = _hrm.find_highest_free(&expanded);
6152
6153 if (index != G1_NO_HRM_INDEX) {
6154 if (expanded) {
6155 ergo_verbose1(ErgoHeapSizing,
6156 "attempt heap expansion",
6157 ergo_format_reason("requested address range outside heap bounds")
6158 ergo_format_byte("region size"),
6159 HeapRegion::GrainWords * HeapWordSize);
6160 }
6161 _hrm.allocate_free_regions_starting_at(index, 1);
6162 return region_at(index);
6163 }
6164 return NULL;
6165 }
6166
6167 // Heap region set verification
6168
6169 class VerifyRegionListsClosure : public HeapRegionClosure {
6170 private:
6171 HeapRegionSet* _old_set;
6172 HeapRegionSet* _humongous_set;
6173 HeapRegionManager* _hrm;
6174
6175 public:
6176 HeapRegionSetCount _old_count;
6177 HeapRegionSetCount _humongous_count;
6178 HeapRegionSetCount _free_count;
6179
6180 VerifyRegionListsClosure(HeapRegionSet* old_set,
6181 HeapRegionSet* humongous_set,
6182 HeapRegionManager* hrm) :
6183 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6184 _old_count(), _humongous_count(), _free_count(){ }
6185
6186 bool doHeapRegion(HeapRegion* hr) {
6187 if (hr->is_young()) {
6188 // TODO
6189 } else if (hr->is_humongous()) {
6190 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6191 _humongous_count.increment(1u, hr->capacity());
6192 } else if (hr->is_empty()) {
6193 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6194 _free_count.increment(1u, hr->capacity());
6195 } else if (hr->is_old()) {
6196 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6197 _old_count.increment(1u, hr->capacity());
6198 } else {
6199 // There are no other valid region types. Check for one invalid
6200 // one we can identify: pinned without old or humongous set.
6201 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6202 ShouldNotReachHere();
6203 }
6204 return false;
6205 }
6206
6207 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6208 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6209 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6210 old_set->total_capacity_bytes(), _old_count.capacity());
6211
6212 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6213 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6214 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6215
6216 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());
6217 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6218 free_list->total_capacity_bytes(), _free_count.capacity());
6219 }
6220 };
6221
6222 void G1CollectedHeap::verify_region_sets() {
6223 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6224
6225 // First, check the explicit lists.
6226 _hrm.verify();
6227 {
6228 // Given that a concurrent operation might be adding regions to
6229 // the secondary free list we have to take the lock before
6230 // verifying it.
6231 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6232 _secondary_free_list.verify_list();
6233 }
6234
6235 // If a concurrent region freeing operation is in progress it will
6236 // be difficult to correctly attributed any free regions we come
6237 // across to the correct free list given that they might belong to
6238 // one of several (free_list, secondary_free_list, any local lists,
6239 // etc.). So, if that's the case we will skip the rest of the
6240 // verification operation. Alternatively, waiting for the concurrent
6241 // operation to complete will have a non-trivial effect on the GC's
6242 // operation (no concurrent operation will last longer than the
6243 // interval between two calls to verification) and it might hide
6244 // any issues that we would like to catch during testing.
6245 if (free_regions_coming()) {
6246 return;
6247 }
6248
6249 // Make sure we append the secondary_free_list on the free_list so
6250 // that all free regions we will come across can be safely
6251 // attributed to the free_list.
6252 append_secondary_free_list_if_not_empty_with_lock();
6253
6254 // Finally, make sure that the region accounting in the lists is
6255 // consistent with what we see in the heap.
6256
6257 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6258 heap_region_iterate(&cl);
6259 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6260 }
6261
6262 // Optimized nmethod scanning
6263
6264 class RegisterNMethodOopClosure: public OopClosure {
6265 G1CollectedHeap* _g1h;
6266 nmethod* _nm;
6267
6268 template <class T> void do_oop_work(T* p) {
6269 T heap_oop = oopDesc::load_heap_oop(p);
6270 if (!oopDesc::is_null(heap_oop)) {
6271 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6272 HeapRegion* hr = _g1h->heap_region_containing(obj);
6273 assert(!hr->is_continues_humongous(),
6274 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6275 " starting at " HR_FORMAT,
6276 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6277
6278 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6279 hr->add_strong_code_root_locked(_nm);
6280 }
6281 }
6282
6283 public:
6284 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6285 _g1h(g1h), _nm(nm) {}
6286
6287 void do_oop(oop* p) { do_oop_work(p); }
6288 void do_oop(narrowOop* p) { do_oop_work(p); }
6289 };
6290
6291 class UnregisterNMethodOopClosure: public OopClosure {
6292 G1CollectedHeap* _g1h;
6293 nmethod* _nm;
6294
6295 template <class T> void do_oop_work(T* p) {
6296 T heap_oop = oopDesc::load_heap_oop(p);
6297 if (!oopDesc::is_null(heap_oop)) {
6298 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6299 HeapRegion* hr = _g1h->heap_region_containing(obj);
6300 assert(!hr->is_continues_humongous(),
6301 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6302 " starting at " HR_FORMAT,
6303 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6304
6305 hr->remove_strong_code_root(_nm);
6306 }
6307 }
6308
6309 public:
6310 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6311 _g1h(g1h), _nm(nm) {}
6312
6313 void do_oop(oop* p) { do_oop_work(p); }
6314 void do_oop(narrowOop* p) { do_oop_work(p); }
6315 };
6316
6317 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6318 CollectedHeap::register_nmethod(nm);
6319
6320 guarantee(nm != NULL, "sanity");
6321 RegisterNMethodOopClosure reg_cl(this, nm);
6322 nm->oops_do(®_cl);
6323 }
6324
6325 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6326 CollectedHeap::unregister_nmethod(nm);
6327
6328 guarantee(nm != NULL, "sanity");
6329 UnregisterNMethodOopClosure reg_cl(this, nm);
6330 nm->oops_do(®_cl, true);
6331 }
6332
6333 void G1CollectedHeap::purge_code_root_memory() {
6334 double purge_start = os::elapsedTime();
6335 G1CodeRootSet::purge();
6336 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6337 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6338 }
6339
6340 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6341 G1CollectedHeap* _g1h;
6342
6343 public:
6344 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6345 _g1h(g1h) {}
6346
6347 void do_code_blob(CodeBlob* cb) {
6348 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6349 if (nm == NULL) {
6350 return;
6351 }
6352
6353 if (ScavengeRootsInCode) {
6354 _g1h->register_nmethod(nm);
6355 }
6356 }
6357 };
6358
6359 void G1CollectedHeap::rebuild_strong_code_roots() {
6360 RebuildStrongCodeRootClosure blob_cl(this);
6361 CodeCache::blobs_do(&blob_cl);
6362 }