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/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1Log.hpp"
43 #include "gc/g1/g1MarkSweep.hpp"
44 #include "gc/g1/g1OopClosures.inline.hpp"
45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc/g1/g1RemSet.inline.hpp"
48 #include "gc/g1/g1RootClosures.hpp"
49 #include "gc/g1/g1RootProcessor.hpp"
50 #include "gc/g1/g1StringDedup.hpp"
51 #include "gc/g1/g1YCTypes.hpp"
52 #include "gc/g1/heapRegion.inline.hpp"
53 #include "gc/g1/heapRegionRemSet.hpp"
54 #include "gc/g1/heapRegionSet.inline.hpp"
55 #include "gc/g1/suspendibleThreadSet.hpp"
56 #include "gc/g1/vm_operations_g1.hpp"
57 #include "gc/shared/gcHeapSummary.hpp"
58 #include "gc/shared/gcId.hpp"
59 #include "gc/shared/gcLocker.inline.hpp"
60 #include "gc/shared/gcTimer.hpp"
61 #include "gc/shared/gcTrace.hpp"
62 #include "gc/shared/gcTraceTime.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "memory/allocation.hpp"
68 #include "memory/iterator.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/init.hpp"
72 #include "runtime/orderAccess.inline.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "utilities/globalDefinitions.hpp"
75 #include "utilities/stack.inline.hpp"
76
77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_processed;
117
118 public:
119 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 *card_ptr = CardTableModRefBS::dirty_card_val();
123 _num_processed++;
124 return true;
125 }
126
127 size_t num_processed() const { return _num_processed; }
128 };
129
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
142 {
143 // Claim the right to put the region on the dirty cards region list
144 // by installing a self pointer.
145 HeapRegion* next = hr->get_next_dirty_cards_region();
146 if (next == NULL) {
147 HeapRegion* res = (HeapRegion*)
148 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
149 NULL);
150 if (res == NULL) {
151 HeapRegion* head;
152 do {
153 // Put the region to the dirty cards region list.
154 head = _dirty_cards_region_list;
155 next = (HeapRegion*)
156 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
157 if (next == head) {
158 assert(hr->get_next_dirty_cards_region() == hr,
159 "hr->get_next_dirty_cards_region() != hr");
160 if (next == NULL) {
161 // The last region in the list points to itself.
162 hr->set_next_dirty_cards_region(hr);
163 } else {
164 hr->set_next_dirty_cards_region(next);
165 }
166 }
167 } while (next != head);
168 }
169 }
170 }
171
172 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
173 {
174 HeapRegion* head;
175 HeapRegion* hr;
176 do {
177 head = _dirty_cards_region_list;
178 if (head == NULL) {
179 return NULL;
180 }
181 HeapRegion* new_head = head->get_next_dirty_cards_region();
182 if (head == new_head) {
183 // The last region.
184 new_head = NULL;
185 }
186 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
187 head);
188 } while (hr != head);
189 assert(hr != NULL, "invariant");
190 hr->set_next_dirty_cards_region(NULL);
191 return hr;
192 }
193
194 // Returns true if the reference points to an object that
195 // can move in an incremental collection.
196 bool G1CollectedHeap::is_scavengable(const void* p) {
197 HeapRegion* hr = heap_region_containing(p);
198 return !hr->is_pinned();
199 }
200
201 // Private methods.
202
203 HeapRegion*
204 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
205 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
206 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
207 if (!_secondary_free_list.is_empty()) {
208 if (G1ConcRegionFreeingVerbose) {
209 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
210 "secondary_free_list has %u entries",
211 _secondary_free_list.length());
212 }
213 // It looks as if there are free regions available on the
214 // secondary_free_list. Let's move them to the free_list and try
215 // again to allocate from it.
216 append_secondary_free_list();
217
218 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
219 "empty we should have moved at least one entry to the free_list");
220 HeapRegion* res = _hrm.allocate_free_region(is_old);
221 if (G1ConcRegionFreeingVerbose) {
222 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
223 "allocated " HR_FORMAT " from secondary_free_list",
224 HR_FORMAT_PARAMS(res));
225 }
226 return res;
227 }
228
229 // Wait here until we get notified either when (a) there are no
230 // more free regions coming or (b) some regions have been moved on
231 // the secondary_free_list.
232 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
233 }
234
235 if (G1ConcRegionFreeingVerbose) {
236 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
237 "could not allocate from secondary_free_list");
238 }
239 return NULL;
240 }
241
242 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
243 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
244 "the only time we use this to allocate a humongous region is "
245 "when we are allocating a single humongous region");
246
247 HeapRegion* res;
248 if (G1StressConcRegionFreeing) {
249 if (!_secondary_free_list.is_empty()) {
250 if (G1ConcRegionFreeingVerbose) {
251 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
252 "forced to look at the secondary_free_list");
253 }
254 res = new_region_try_secondary_free_list(is_old);
255 if (res != NULL) {
256 return res;
257 }
258 }
259 }
260
261 res = _hrm.allocate_free_region(is_old);
262
263 if (res == NULL) {
264 if (G1ConcRegionFreeingVerbose) {
265 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
266 "res == NULL, trying the secondary_free_list");
267 }
268 res = new_region_try_secondary_free_list(is_old);
269 }
270 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
271 // Currently, only attempts to allocate GC alloc regions set
272 // do_expand to true. So, we should only reach here during a
273 // safepoint. If this assumption changes we might have to
274 // reconsider the use of _expand_heap_after_alloc_failure.
275 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
276
277 ergo_verbose1(ErgoHeapSizing,
278 "attempt heap expansion",
279 ergo_format_reason("region allocation request failed")
280 ergo_format_byte("allocation request"),
281 word_size * HeapWordSize);
282 if (expand(word_size * HeapWordSize)) {
283 // Given that expand() succeeded in expanding the heap, and we
284 // always expand the heap by an amount aligned to the heap
285 // region size, the free list should in theory not be empty.
286 // In either case allocate_free_region() will check for NULL.
287 res = _hrm.allocate_free_region(is_old);
288 } else {
289 _expand_heap_after_alloc_failure = false;
290 }
291 }
292 return res;
293 }
294
295 HeapWord*
296 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
297 uint num_regions,
298 size_t word_size,
299 AllocationContext_t context) {
300 assert(first != G1_NO_HRM_INDEX, "pre-condition");
301 assert(is_humongous(word_size), "word_size should be humongous");
302 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
303
304 // Index of last region in the series + 1.
305 uint last = first + num_regions;
306
307 // We need to initialize the region(s) we just discovered. This is
308 // a bit tricky given that it can happen concurrently with
309 // refinement threads refining cards on these regions and
310 // potentially wanting to refine the BOT as they are scanning
311 // those cards (this can happen shortly after a cleanup; see CR
312 // 6991377). So we have to set up the region(s) carefully and in
313 // a specific order.
314
315 // The word size sum of all the regions we will allocate.
316 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
317 assert(word_size <= word_size_sum, "sanity");
318
319 // This will be the "starts humongous" region.
320 HeapRegion* first_hr = region_at(first);
321 // The header of the new object will be placed at the bottom of
322 // the first region.
323 HeapWord* new_obj = first_hr->bottom();
324 // This will be the new top of the new object.
325 HeapWord* obj_top = new_obj + word_size;
326
327 // First, we need to zero the header of the space that we will be
328 // allocating. When we update top further down, some refinement
329 // threads might try to scan the region. By zeroing the header we
330 // ensure that any thread that will try to scan the region will
331 // come across the zero klass word and bail out.
332 //
333 // NOTE: It would not have been correct to have used
334 // CollectedHeap::fill_with_object() and make the space look like
335 // an int array. The thread that is doing the allocation will
336 // later update the object header to a potentially different array
337 // type and, for a very short period of time, the klass and length
338 // fields will be inconsistent. This could cause a refinement
339 // thread to calculate the object size incorrectly.
340 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
341
342 // We will set up the first region as "starts humongous". This
343 // will also update the BOT covering all the regions to reflect
344 // that there is a single object that starts at the bottom of the
345 // first region.
346 first_hr->set_starts_humongous(obj_top);
347 first_hr->set_allocation_context(context);
348 // Then, if there are any, we will set up the "continues
349 // humongous" regions.
350 HeapRegion* hr = NULL;
351 for (uint i = first + 1; i < last; ++i) {
352 hr = region_at(i);
353 hr->set_continues_humongous(first_hr);
354 hr->set_allocation_context(context);
355 }
356
357 // Up to this point no concurrent thread would have been able to
358 // do any scanning on any region in this series. All the top
359 // fields still point to bottom, so the intersection between
360 // [bottom,top] and [card_start,card_end] will be empty. Before we
361 // update the top fields, we'll do a storestore to make sure that
362 // no thread sees the update to top before the zeroing of the
363 // object header and the BOT initialization.
364 OrderAccess::storestore();
365
366 // Now that the BOT and the object header have been initialized,
367 // we can update top of the "starts humongous" region.
368 first_hr->set_top(MIN2(first_hr->end(), obj_top));
369 if (_hr_printer.is_active()) {
370 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
371 }
372
373 // Now, we will update the top fields of the "continues humongous"
374 // regions.
375 hr = NULL;
376 for (uint i = first + 1; i < last; ++i) {
377 hr = region_at(i);
378 if ((i + 1) == last) {
379 // last continues humongous region
380 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
381 "new_top should fall on this region");
382 hr->set_top(obj_top);
383 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
384 } else {
385 // not last one
386 assert(obj_top > hr->end(), "obj_top should be above this region");
387 hr->set_top(hr->end());
388 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
389 }
390 }
391 // If we have continues humongous regions (hr != NULL), its top should
392 // match obj_top.
393 assert(hr == NULL || (hr->top() == obj_top), "sanity");
394 check_bitmaps("Humongous Region Allocation", first_hr);
395
396 increase_used(word_size * HeapWordSize);
397
398 for (uint i = first; i < last; ++i) {
399 _humongous_set.add(region_at(i));
400 }
401
402 return new_obj;
403 }
404
405 // If could fit into free regions w/o expansion, try.
406 // Otherwise, if can expand, do so.
407 // Otherwise, if using ex regions might help, try with ex given back.
408 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
409 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
410
411 verify_region_sets_optional();
412
413 uint first = G1_NO_HRM_INDEX;
414 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
415
416 if (obj_regions == 1) {
417 // Only one region to allocate, try to use a fast path by directly allocating
418 // from the free lists. Do not try to expand here, we will potentially do that
419 // later.
420 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
421 if (hr != NULL) {
422 first = hr->hrm_index();
423 }
424 } else {
425 // We can't allocate humongous regions spanning more than one region while
426 // cleanupComplete() is running, since some of the regions we find to be
427 // empty might not yet be added to the free list. It is not straightforward
428 // to know in which list they are on so that we can remove them. We only
429 // need to do this if we need to allocate more than one region to satisfy the
430 // current humongous allocation request. If we are only allocating one region
431 // we use the one-region region allocation code (see above), that already
432 // potentially waits for regions from the secondary free list.
433 wait_while_free_regions_coming();
434 append_secondary_free_list_if_not_empty_with_lock();
435
436 // Policy: Try only empty regions (i.e. already committed first). Maybe we
437 // are lucky enough to find some.
438 first = _hrm.find_contiguous_only_empty(obj_regions);
439 if (first != G1_NO_HRM_INDEX) {
440 _hrm.allocate_free_regions_starting_at(first, obj_regions);
441 }
442 }
443
444 if (first == G1_NO_HRM_INDEX) {
445 // Policy: We could not find enough regions for the humongous object in the
446 // free list. Look through the heap to find a mix of free and uncommitted regions.
447 // If so, try expansion.
448 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
449 if (first != G1_NO_HRM_INDEX) {
450 // We found something. Make sure these regions are committed, i.e. expand
451 // the heap. Alternatively we could do a defragmentation GC.
452 ergo_verbose1(ErgoHeapSizing,
453 "attempt heap expansion",
454 ergo_format_reason("humongous allocation request failed")
455 ergo_format_byte("allocation request"),
456 word_size * HeapWordSize);
457
458 _hrm.expand_at(first, obj_regions);
459 g1_policy()->record_new_heap_size(num_regions());
460
461 #ifdef ASSERT
462 for (uint i = first; i < first + obj_regions; ++i) {
463 HeapRegion* hr = region_at(i);
464 assert(hr->is_free(), "sanity");
465 assert(hr->is_empty(), "sanity");
466 assert(is_on_master_free_list(hr), "sanity");
467 }
468 #endif
469 _hrm.allocate_free_regions_starting_at(first, obj_regions);
470 } else {
471 // Policy: Potentially trigger a defragmentation GC.
472 }
473 }
474
475 HeapWord* result = NULL;
476 if (first != G1_NO_HRM_INDEX) {
477 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
478 word_size, context);
479 assert(result != NULL, "it should always return a valid result");
480
481 // A successful humongous object allocation changes the used space
482 // information of the old generation so we need to recalculate the
483 // sizes and update the jstat counters here.
484 g1mm()->update_sizes();
485 }
486
487 verify_region_sets_optional();
488
489 return result;
490 }
491
492 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
493 assert_heap_not_locked_and_not_at_safepoint();
494 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
495
496 uint dummy_gc_count_before;
497 uint dummy_gclocker_retry_count = 0;
498 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
499 }
500
501 HeapWord*
502 G1CollectedHeap::mem_allocate(size_t word_size,
503 bool* gc_overhead_limit_was_exceeded) {
504 assert_heap_not_locked_and_not_at_safepoint();
505
506 // Loop until the allocation is satisfied, or unsatisfied after GC.
507 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
508 uint gc_count_before;
509
510 HeapWord* result = NULL;
511 if (!is_humongous(word_size)) {
512 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
513 } else {
514 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
515 }
516 if (result != NULL) {
517 return result;
518 }
519
520 // Create the garbage collection operation...
521 VM_G1CollectForAllocation op(gc_count_before, word_size);
522 op.set_allocation_context(AllocationContext::current());
523
524 // ...and get the VM thread to execute it.
525 VMThread::execute(&op);
526
527 if (op.prologue_succeeded() && op.pause_succeeded()) {
528 // If the operation was successful we'll return the result even
529 // if it is NULL. If the allocation attempt failed immediately
530 // after a Full GC, it's unlikely we'll be able to allocate now.
531 HeapWord* result = op.result();
532 if (result != NULL && !is_humongous(word_size)) {
533 // Allocations that take place on VM operations do not do any
534 // card dirtying and we have to do it here. We only have to do
535 // this for non-humongous allocations, though.
536 dirty_young_block(result, word_size);
537 }
538 return result;
539 } else {
540 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
541 return NULL;
542 }
543 assert(op.result() == NULL,
544 "the result should be NULL if the VM op did not succeed");
545 }
546
547 // Give a warning if we seem to be looping forever.
548 if ((QueuedAllocationWarningCount > 0) &&
549 (try_count % QueuedAllocationWarningCount == 0)) {
550 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
551 }
552 }
553
554 ShouldNotReachHere();
555 return NULL;
556 }
557
558 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
559 AllocationContext_t context,
560 uint* gc_count_before_ret,
561 uint* gclocker_retry_count_ret) {
562 // Make sure you read the note in attempt_allocation_humongous().
563
564 assert_heap_not_locked_and_not_at_safepoint();
565 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
566 "be called for humongous allocation requests");
567
568 // We should only get here after the first-level allocation attempt
569 // (attempt_allocation()) failed to allocate.
570
571 // We will loop until a) we manage to successfully perform the
572 // allocation or b) we successfully schedule a collection which
573 // fails to perform the allocation. b) is the only case when we'll
574 // return NULL.
575 HeapWord* result = NULL;
576 for (int try_count = 1; /* we'll return */; try_count += 1) {
577 bool should_try_gc;
578 uint gc_count_before;
579
580 {
581 MutexLockerEx x(Heap_lock);
582 result = _allocator->attempt_allocation_locked(word_size, context);
583 if (result != NULL) {
584 return result;
585 }
586
587 if (GC_locker::is_active_and_needs_gc()) {
588 if (g1_policy()->can_expand_young_list()) {
589 // No need for an ergo verbose message here,
590 // can_expand_young_list() does this when it returns true.
591 result = _allocator->attempt_allocation_force(word_size, context);
592 if (result != NULL) {
593 return result;
594 }
595 }
596 should_try_gc = false;
597 } else {
598 // The GCLocker may not be active but the GCLocker initiated
599 // GC may not yet have been performed (GCLocker::needs_gc()
600 // returns true). In this case we do not try this GC and
601 // wait until the GCLocker initiated GC is performed, and
602 // then retry the allocation.
603 if (GC_locker::needs_gc()) {
604 should_try_gc = false;
605 } else {
606 // Read the GC count while still holding the Heap_lock.
607 gc_count_before = total_collections();
608 should_try_gc = true;
609 }
610 }
611 }
612
613 if (should_try_gc) {
614 bool succeeded;
615 result = do_collection_pause(word_size, gc_count_before, &succeeded,
616 GCCause::_g1_inc_collection_pause);
617 if (result != NULL) {
618 assert(succeeded, "only way to get back a non-NULL result");
619 return result;
620 }
621
622 if (succeeded) {
623 // If we get here we successfully scheduled a collection which
624 // failed to allocate. No point in trying to allocate
625 // further. We'll just return NULL.
626 MutexLockerEx x(Heap_lock);
627 *gc_count_before_ret = total_collections();
628 return NULL;
629 }
630 } else {
631 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
632 MutexLockerEx x(Heap_lock);
633 *gc_count_before_ret = total_collections();
634 return NULL;
635 }
636 // The GCLocker is either active or the GCLocker initiated
637 // GC has not yet been performed. Stall until it is and
638 // then retry the allocation.
639 GC_locker::stall_until_clear();
640 (*gclocker_retry_count_ret) += 1;
641 }
642
643 // We can reach here if we were unsuccessful in scheduling a
644 // collection (because another thread beat us to it) or if we were
645 // stalled due to the GC locker. In either can we should retry the
646 // allocation attempt in case another thread successfully
647 // performed a collection and reclaimed enough space. We do the
648 // first attempt (without holding the Heap_lock) here and the
649 // follow-on attempt will be at the start of the next loop
650 // iteration (after taking the Heap_lock).
651 result = _allocator->attempt_allocation(word_size, context);
652 if (result != NULL) {
653 return result;
654 }
655
656 // Give a warning if we seem to be looping forever.
657 if ((QueuedAllocationWarningCount > 0) &&
658 (try_count % QueuedAllocationWarningCount == 0)) {
659 warning("G1CollectedHeap::attempt_allocation_slow() "
660 "retries %d times", try_count);
661 }
662 }
663
664 ShouldNotReachHere();
665 return NULL;
666 }
667
668 void G1CollectedHeap::begin_archive_alloc_range() {
669 assert_at_safepoint(true /* should_be_vm_thread */);
670 if (_archive_allocator == NULL) {
671 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
672 }
673 }
674
675 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
676 // Allocations in archive regions cannot be of a size that would be considered
677 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
678 // may be different at archive-restore time.
679 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
680 }
681
682 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
683 assert_at_safepoint(true /* should_be_vm_thread */);
684 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
685 if (is_archive_alloc_too_large(word_size)) {
686 return NULL;
687 }
688 return _archive_allocator->archive_mem_allocate(word_size);
689 }
690
691 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
692 size_t end_alignment_in_bytes) {
693 assert_at_safepoint(true /* should_be_vm_thread */);
694 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
695
696 // Call complete_archive to do the real work, filling in the MemRegion
697 // array with the archive regions.
698 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
699 delete _archive_allocator;
700 _archive_allocator = NULL;
701 }
702
703 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
704 assert(ranges != NULL, "MemRegion array NULL");
705 assert(count != 0, "No MemRegions provided");
706 MemRegion reserved = _hrm.reserved();
707 for (size_t i = 0; i < count; i++) {
708 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
709 return false;
710 }
711 }
712 return true;
713 }
714
715 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
716 assert(!is_init_completed(), "Expect to be called at JVM init time");
717 assert(ranges != NULL, "MemRegion array NULL");
718 assert(count != 0, "No MemRegions provided");
719 MutexLockerEx x(Heap_lock);
720
721 MemRegion reserved = _hrm.reserved();
722 HeapWord* prev_last_addr = NULL;
723 HeapRegion* prev_last_region = NULL;
724
725 // Temporarily disable pretouching of heap pages. This interface is used
726 // when mmap'ing archived heap data in, so pre-touching is wasted.
727 FlagSetting fs(AlwaysPreTouch, false);
728
729 // Enable archive object checking in G1MarkSweep. We have to let it know
730 // about each archive range, so that objects in those ranges aren't marked.
731 G1MarkSweep::enable_archive_object_check();
732
733 // For each specified MemRegion range, allocate the corresponding G1
734 // regions and mark them as archive regions. We expect the ranges in
735 // ascending starting address order, without overlap.
736 for (size_t i = 0; i < count; i++) {
737 MemRegion curr_range = ranges[i];
738 HeapWord* start_address = curr_range.start();
739 size_t word_size = curr_range.word_size();
740 HeapWord* last_address = curr_range.last();
741 size_t commits = 0;
742
743 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
744 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
745 p2i(start_address), p2i(last_address));
746 guarantee(start_address > prev_last_addr,
747 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
748 p2i(start_address), p2i(prev_last_addr));
749 prev_last_addr = last_address;
750
751 // Check for ranges that start in the same G1 region in which the previous
752 // range ended, and adjust the start address so we don't try to allocate
753 // the same region again. If the current range is entirely within that
754 // region, skip it, just adjusting the recorded top.
755 HeapRegion* start_region = _hrm.addr_to_region(start_address);
756 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
757 start_address = start_region->end();
758 if (start_address > last_address) {
759 increase_used(word_size * HeapWordSize);
760 start_region->set_top(last_address + 1);
761 continue;
762 }
763 start_region->set_top(start_address);
764 curr_range = MemRegion(start_address, last_address + 1);
765 start_region = _hrm.addr_to_region(start_address);
766 }
767
768 // Perform the actual region allocation, exiting if it fails.
769 // Then note how much new space we have allocated.
770 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
771 return false;
772 }
773 increase_used(word_size * HeapWordSize);
774 if (commits != 0) {
775 ergo_verbose1(ErgoHeapSizing,
776 "attempt heap expansion",
777 ergo_format_reason("allocate archive regions")
778 ergo_format_byte("total size"),
779 HeapRegion::GrainWords * HeapWordSize * commits);
780 }
781
782 // Mark each G1 region touched by the range as archive, add it to the old set,
783 // and set the allocation context and top.
784 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
785 HeapRegion* last_region = _hrm.addr_to_region(last_address);
786 prev_last_region = last_region;
787
788 while (curr_region != NULL) {
789 assert(curr_region->is_empty() && !curr_region->is_pinned(),
790 "Region already in use (index %u)", curr_region->hrm_index());
791 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
792 curr_region->set_allocation_context(AllocationContext::system());
793 curr_region->set_archive();
794 _old_set.add(curr_region);
795 if (curr_region != last_region) {
796 curr_region->set_top(curr_region->end());
797 curr_region = _hrm.next_region_in_heap(curr_region);
798 } else {
799 curr_region->set_top(last_address + 1);
800 curr_region = NULL;
801 }
802 }
803
804 // Notify mark-sweep of the archive range.
805 G1MarkSweep::set_range_archive(curr_range, true);
806 }
807 return true;
808 }
809
810 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
811 assert(!is_init_completed(), "Expect to be called at JVM init time");
812 assert(ranges != NULL, "MemRegion array NULL");
813 assert(count != 0, "No MemRegions provided");
814 MemRegion reserved = _hrm.reserved();
815 HeapWord *prev_last_addr = NULL;
816 HeapRegion* prev_last_region = NULL;
817
818 // For each MemRegion, create filler objects, if needed, in the G1 regions
819 // that contain the address range. The address range actually within the
820 // MemRegion will not be modified. That is assumed to have been initialized
821 // elsewhere, probably via an mmap of archived heap data.
822 MutexLockerEx x(Heap_lock);
823 for (size_t i = 0; i < count; i++) {
824 HeapWord* start_address = ranges[i].start();
825 HeapWord* last_address = ranges[i].last();
826
827 assert(reserved.contains(start_address) && reserved.contains(last_address),
828 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
829 p2i(start_address), p2i(last_address));
830 assert(start_address > prev_last_addr,
831 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
832 p2i(start_address), p2i(prev_last_addr));
833
834 HeapRegion* start_region = _hrm.addr_to_region(start_address);
835 HeapRegion* last_region = _hrm.addr_to_region(last_address);
836 HeapWord* bottom_address = start_region->bottom();
837
838 // Check for a range beginning in the same region in which the
839 // previous one ended.
840 if (start_region == prev_last_region) {
841 bottom_address = prev_last_addr + 1;
842 }
843
844 // Verify that the regions were all marked as archive regions by
845 // alloc_archive_regions.
846 HeapRegion* curr_region = start_region;
847 while (curr_region != NULL) {
848 guarantee(curr_region->is_archive(),
849 "Expected archive region at index %u", curr_region->hrm_index());
850 if (curr_region != last_region) {
851 curr_region = _hrm.next_region_in_heap(curr_region);
852 } else {
853 curr_region = NULL;
854 }
855 }
856
857 prev_last_addr = last_address;
858 prev_last_region = last_region;
859
860 // Fill the memory below the allocated range with dummy object(s),
861 // if the region bottom does not match the range start, or if the previous
862 // range ended within the same G1 region, and there is a gap.
863 if (start_address != bottom_address) {
864 size_t fill_size = pointer_delta(start_address, bottom_address);
865 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
866 increase_used(fill_size * HeapWordSize);
867 }
868 }
869 }
870
871 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
872 uint* gc_count_before_ret,
873 uint* gclocker_retry_count_ret) {
874 assert_heap_not_locked_and_not_at_safepoint();
875 assert(!is_humongous(word_size), "attempt_allocation() should not "
876 "be called for humongous allocation requests");
877
878 AllocationContext_t context = AllocationContext::current();
879 HeapWord* result = _allocator->attempt_allocation(word_size, context);
880
881 if (result == NULL) {
882 result = attempt_allocation_slow(word_size,
883 context,
884 gc_count_before_ret,
885 gclocker_retry_count_ret);
886 }
887 assert_heap_not_locked();
888 if (result != NULL) {
889 dirty_young_block(result, word_size);
890 }
891 return result;
892 }
893
894 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
895 assert(!is_init_completed(), "Expect to be called at JVM init time");
896 assert(ranges != NULL, "MemRegion array NULL");
897 assert(count != 0, "No MemRegions provided");
898 MemRegion reserved = _hrm.reserved();
899 HeapWord* prev_last_addr = NULL;
900 HeapRegion* prev_last_region = NULL;
901 size_t size_used = 0;
902 size_t uncommitted_regions = 0;
903
904 // For each Memregion, free the G1 regions that constitute it, and
905 // notify mark-sweep that the range is no longer to be considered 'archive.'
906 MutexLockerEx x(Heap_lock);
907 for (size_t i = 0; i < count; i++) {
908 HeapWord* start_address = ranges[i].start();
909 HeapWord* last_address = ranges[i].last();
910
911 assert(reserved.contains(start_address) && reserved.contains(last_address),
912 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
913 p2i(start_address), p2i(last_address));
914 assert(start_address > prev_last_addr,
915 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
916 p2i(start_address), p2i(prev_last_addr));
917 size_used += ranges[i].byte_size();
918 prev_last_addr = last_address;
919
920 HeapRegion* start_region = _hrm.addr_to_region(start_address);
921 HeapRegion* last_region = _hrm.addr_to_region(last_address);
922
923 // Check for ranges that start in the same G1 region in which the previous
924 // range ended, and adjust the start address so we don't try to free
925 // the same region again. If the current range is entirely within that
926 // region, skip it.
927 if (start_region == prev_last_region) {
928 start_address = start_region->end();
929 if (start_address > last_address) {
930 continue;
931 }
932 start_region = _hrm.addr_to_region(start_address);
933 }
934 prev_last_region = last_region;
935
936 // After verifying that each region was marked as an archive region by
937 // alloc_archive_regions, set it free and empty and uncommit it.
938 HeapRegion* curr_region = start_region;
939 while (curr_region != NULL) {
940 guarantee(curr_region->is_archive(),
941 "Expected archive region at index %u", curr_region->hrm_index());
942 uint curr_index = curr_region->hrm_index();
943 _old_set.remove(curr_region);
944 curr_region->set_free();
945 curr_region->set_top(curr_region->bottom());
946 if (curr_region != last_region) {
947 curr_region = _hrm.next_region_in_heap(curr_region);
948 } else {
949 curr_region = NULL;
950 }
951 _hrm.shrink_at(curr_index, 1);
952 uncommitted_regions++;
953 }
954
955 // Notify mark-sweep that this is no longer an archive range.
956 G1MarkSweep::set_range_archive(ranges[i], false);
957 }
958
959 if (uncommitted_regions != 0) {
960 ergo_verbose1(ErgoHeapSizing,
961 "attempt heap shrinking",
962 ergo_format_reason("uncommitted archive regions")
963 ergo_format_byte("total size"),
964 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
965 }
966 decrease_used(size_used);
967 }
968
969 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
970 uint* gc_count_before_ret,
971 uint* gclocker_retry_count_ret) {
972 // The structure of this method has a lot of similarities to
973 // attempt_allocation_slow(). The reason these two were not merged
974 // into a single one is that such a method would require several "if
975 // allocation is not humongous do this, otherwise do that"
976 // conditional paths which would obscure its flow. In fact, an early
977 // version of this code did use a unified method which was harder to
978 // follow and, as a result, it had subtle bugs that were hard to
979 // track down. So keeping these two methods separate allows each to
980 // be more readable. It will be good to keep these two in sync as
981 // much as possible.
982
983 assert_heap_not_locked_and_not_at_safepoint();
984 assert(is_humongous(word_size), "attempt_allocation_humongous() "
985 "should only be called for humongous allocations");
986
987 // Humongous objects can exhaust the heap quickly, so we should check if we
988 // need to start a marking cycle at each humongous object allocation. We do
989 // the check before we do the actual allocation. The reason for doing it
990 // before the allocation is that we avoid having to keep track of the newly
991 // allocated memory while we do a GC.
992 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
993 word_size)) {
994 collect(GCCause::_g1_humongous_allocation);
995 }
996
997 // We will loop until a) we manage to successfully perform the
998 // allocation or b) we successfully schedule a collection which
999 // fails to perform the allocation. b) is the only case when we'll
1000 // return NULL.
1001 HeapWord* result = NULL;
1002 for (int try_count = 1; /* we'll return */; try_count += 1) {
1003 bool should_try_gc;
1004 uint gc_count_before;
1005
1006 {
1007 MutexLockerEx x(Heap_lock);
1008
1009 // Given that humongous objects are not allocated in young
1010 // regions, we'll first try to do the allocation without doing a
1011 // collection hoping that there's enough space in the heap.
1012 result = humongous_obj_allocate(word_size, AllocationContext::current());
1013 if (result != NULL) {
1014 return result;
1015 }
1016
1017 if (GC_locker::is_active_and_needs_gc()) {
1018 should_try_gc = false;
1019 } else {
1020 // The GCLocker may not be active but the GCLocker initiated
1021 // GC may not yet have been performed (GCLocker::needs_gc()
1022 // returns true). In this case we do not try this GC and
1023 // wait until the GCLocker initiated GC is performed, and
1024 // then retry the allocation.
1025 if (GC_locker::needs_gc()) {
1026 should_try_gc = false;
1027 } else {
1028 // Read the GC count while still holding the Heap_lock.
1029 gc_count_before = total_collections();
1030 should_try_gc = true;
1031 }
1032 }
1033 }
1034
1035 if (should_try_gc) {
1036 // If we failed to allocate the humongous object, we should try to
1037 // do a collection pause (if we're allowed) in case it reclaims
1038 // enough space for the allocation to succeed after the pause.
1039
1040 bool succeeded;
1041 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1042 GCCause::_g1_humongous_allocation);
1043 if (result != NULL) {
1044 assert(succeeded, "only way to get back a non-NULL result");
1045 return result;
1046 }
1047
1048 if (succeeded) {
1049 // If we get here we successfully scheduled a collection which
1050 // failed to allocate. No point in trying to allocate
1051 // further. We'll just return NULL.
1052 MutexLockerEx x(Heap_lock);
1053 *gc_count_before_ret = total_collections();
1054 return NULL;
1055 }
1056 } else {
1057 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1058 MutexLockerEx x(Heap_lock);
1059 *gc_count_before_ret = total_collections();
1060 return NULL;
1061 }
1062 // The GCLocker is either active or the GCLocker initiated
1063 // GC has not yet been performed. Stall until it is and
1064 // then retry the allocation.
1065 GC_locker::stall_until_clear();
1066 (*gclocker_retry_count_ret) += 1;
1067 }
1068
1069 // We can reach here if we were unsuccessful in scheduling a
1070 // collection (because another thread beat us to it) or if we were
1071 // stalled due to the GC locker. In either can we should retry the
1072 // allocation attempt in case another thread successfully
1073 // performed a collection and reclaimed enough space. Give a
1074 // warning if we seem to be looping forever.
1075
1076 if ((QueuedAllocationWarningCount > 0) &&
1077 (try_count % QueuedAllocationWarningCount == 0)) {
1078 warning("G1CollectedHeap::attempt_allocation_humongous() "
1079 "retries %d times", try_count);
1080 }
1081 }
1082
1083 ShouldNotReachHere();
1084 return NULL;
1085 }
1086
1087 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1088 AllocationContext_t context,
1089 bool expect_null_mutator_alloc_region) {
1090 assert_at_safepoint(true /* should_be_vm_thread */);
1091 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1092 "the current alloc region was unexpectedly found to be non-NULL");
1093
1094 if (!is_humongous(word_size)) {
1095 return _allocator->attempt_allocation_locked(word_size, context);
1096 } else {
1097 HeapWord* result = humongous_obj_allocate(word_size, context);
1098 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1099 collector_state()->set_initiate_conc_mark_if_possible(true);
1100 }
1101 return result;
1102 }
1103
1104 ShouldNotReachHere();
1105 }
1106
1107 class PostMCRemSetClearClosure: public HeapRegionClosure {
1108 G1CollectedHeap* _g1h;
1109 ModRefBarrierSet* _mr_bs;
1110 public:
1111 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1112 _g1h(g1h), _mr_bs(mr_bs) {}
1113
1114 bool doHeapRegion(HeapRegion* r) {
1115 HeapRegionRemSet* hrrs = r->rem_set();
1116
1117 _g1h->reset_gc_time_stamps(r);
1118
1119 if (r->is_continues_humongous()) {
1120 // We'll assert that the strong code root list and RSet is empty
1121 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1122 assert(hrrs->occupied() == 0, "RSet should be empty");
1123 } else {
1124 hrrs->clear();
1125 }
1126 // You might think here that we could clear just the cards
1127 // corresponding to the used region. But no: if we leave a dirty card
1128 // in a region we might allocate into, then it would prevent that card
1129 // from being enqueued, and cause it to be missed.
1130 // Re: the performance cost: we shouldn't be doing full GC anyway!
1131 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1132
1133 return false;
1134 }
1135 };
1136
1137 void G1CollectedHeap::clear_rsets_post_compaction() {
1138 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1139 heap_region_iterate(&rs_clear);
1140 }
1141
1142 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1143 G1CollectedHeap* _g1h;
1144 UpdateRSOopClosure _cl;
1145 public:
1146 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1147 _cl(g1->g1_rem_set(), worker_i),
1148 _g1h(g1)
1149 { }
1150
1151 bool doHeapRegion(HeapRegion* r) {
1152 if (!r->is_continues_humongous()) {
1153 _cl.set_from(r);
1154 r->oop_iterate(&_cl);
1155 }
1156 return false;
1157 }
1158 };
1159
1160 class ParRebuildRSTask: public AbstractGangTask {
1161 G1CollectedHeap* _g1;
1162 HeapRegionClaimer _hrclaimer;
1163
1164 public:
1165 ParRebuildRSTask(G1CollectedHeap* g1) :
1166 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1167
1168 void work(uint worker_id) {
1169 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1170 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1171 }
1172 };
1173
1174 class PostCompactionPrinterClosure: public HeapRegionClosure {
1175 private:
1176 G1HRPrinter* _hr_printer;
1177 public:
1178 bool doHeapRegion(HeapRegion* hr) {
1179 assert(!hr->is_young(), "not expecting to find young regions");
1180 if (hr->is_free()) {
1181 // We only generate output for non-empty regions.
1182 } else if (hr->is_starts_humongous()) {
1183 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1184 } else if (hr->is_continues_humongous()) {
1185 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1186 } else if (hr->is_archive()) {
1187 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1188 } else if (hr->is_old()) {
1189 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1190 } else {
1191 ShouldNotReachHere();
1192 }
1193 return false;
1194 }
1195
1196 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1197 : _hr_printer(hr_printer) { }
1198 };
1199
1200 void G1CollectedHeap::print_hrm_post_compaction() {
1201 PostCompactionPrinterClosure cl(hr_printer());
1202 heap_region_iterate(&cl);
1203 }
1204
1205 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1206 bool clear_all_soft_refs) {
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_if_necessary_after_full_collection();
1365
1366 if (_hr_printer.is_active()) {
1367 // We should do this after we potentially resize the heap so
1368 // that all the COMMIT / UNCOMMIT events are generated before
1369 // the end GC event.
1370
1371 print_hrm_post_compaction();
1372 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1373 }
1374
1375 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1376 if (hot_card_cache->use_cache()) {
1377 hot_card_cache->reset_card_counts();
1378 hot_card_cache->reset_hot_cache();
1379 }
1380
1381 // Rebuild remembered sets of all regions.
1382 uint n_workers =
1383 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1384 workers()->active_workers(),
1385 Threads::number_of_non_daemon_threads());
1386 workers()->set_active_workers(n_workers);
1387
1388 ParRebuildRSTask rebuild_rs_task(this);
1389 workers()->run_task(&rebuild_rs_task);
1390
1391 // Rebuild the strong code root lists for each region
1392 rebuild_strong_code_roots();
1393
1394 if (true) { // FIXME
1395 MetaspaceGC::compute_new_size();
1396 }
1397
1398 #ifdef TRACESPINNING
1399 ParallelTaskTerminator::print_termination_counts();
1400 #endif
1401
1402 // Discard all rset updates
1403 JavaThread::dirty_card_queue_set().abandon_logs();
1404 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1405
1406 _young_list->reset_sampled_info();
1407 // At this point there should be no regions in the
1408 // entire heap tagged as young.
1409 assert(check_young_list_empty(true /* check_heap */),
1410 "young list should be empty at this point");
1411
1412 // Update the number of full collections that have been completed.
1413 increment_old_marking_cycles_completed(false /* concurrent */);
1414
1415 _hrm.verify_optional();
1416 verify_region_sets_optional();
1417
1418 verify_after_gc();
1419
1420 // Clear the previous marking bitmap, if needed for bitmap verification.
1421 // Note we cannot do this when we clear the next marking bitmap in
1422 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423 // objects marked during a full GC against the previous bitmap.
1424 // But we need to clear it before calling check_bitmaps below since
1425 // the full GC has compacted objects and updated TAMS but not updated
1426 // the prev bitmap.
1427 if (G1VerifyBitmaps) {
1428 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1429 }
1430 check_bitmaps("Full GC End");
1431
1432 // Start a new incremental collection set for the next pause
1433 assert(g1_policy()->collection_set() == NULL, "must be");
1434 g1_policy()->start_incremental_cset_building();
1435
1436 clear_cset_fast_test();
1437
1438 _allocator->init_mutator_alloc_region();
1439
1440 g1_policy()->record_full_collection_end();
1441
1442 if (G1Log::fine()) {
1443 g1_policy()->print_heap_transition();
1444 }
1445
1446 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1447 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1448 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1449 // before any GC notifications are raised.
1450 g1mm()->update_sizes();
1451
1452 gc_epilogue(true);
1453 }
1454
1455 if (G1Log::finer()) {
1456 g1_policy()->print_detailed_heap_transition(true /* full */);
1457 }
1458
1459 print_heap_after_gc();
1460 trace_heap_after_gc(gc_tracer);
1461
1462 post_full_gc_dump(gc_timer);
1463
1464 gc_timer->register_gc_end();
1465 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1466 }
1467
1468 return true;
1469 }
1470
1471 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1472 // Currently, there is no facility in the do_full_collection(bool) API to notify
1473 // the caller that the collection did not succeed (e.g., because it was locked
1474 // out by the GC locker). So, right now, we'll ignore the return value.
1475 bool dummy = do_full_collection(true, /* explicit_gc */
1476 clear_all_soft_refs);
1477 }
1478
1479 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1480 // Include bytes that will be pre-allocated to support collections, as "used".
1481 const size_t used_after_gc = used();
1482 const size_t capacity_after_gc = capacity();
1483 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1484
1485 // This is enforced in arguments.cpp.
1486 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1487 "otherwise the code below doesn't make sense");
1488
1489 // We don't have floating point command-line arguments
1490 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1491 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1492 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1493 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1494
1495 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1496 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1497
1498 // We have to be careful here as these two calculations can overflow
1499 // 32-bit size_t's.
1500 double used_after_gc_d = (double) used_after_gc;
1501 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1502 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1503
1504 // Let's make sure that they are both under the max heap size, which
1505 // by default will make them fit into a size_t.
1506 double desired_capacity_upper_bound = (double) max_heap_size;
1507 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1508 desired_capacity_upper_bound);
1509 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1510 desired_capacity_upper_bound);
1511
1512 // We can now safely turn them into size_t's.
1513 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1514 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1515
1516 // This assert only makes sense here, before we adjust them
1517 // with respect to the min and max heap size.
1518 assert(minimum_desired_capacity <= maximum_desired_capacity,
1519 "minimum_desired_capacity = " SIZE_FORMAT ", "
1520 "maximum_desired_capacity = " SIZE_FORMAT,
1521 minimum_desired_capacity, maximum_desired_capacity);
1522
1523 // Should not be greater than the heap max size. No need to adjust
1524 // it with respect to the heap min size as it's a lower bound (i.e.,
1525 // we'll try to make the capacity larger than it, not smaller).
1526 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1527 // Should not be less than the heap min size. No need to adjust it
1528 // with respect to the heap max size as it's an upper bound (i.e.,
1529 // we'll try to make the capacity smaller than it, not greater).
1530 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1531
1532 if (capacity_after_gc < minimum_desired_capacity) {
1533 // Don't expand unless it's significant
1534 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1535 ergo_verbose4(ErgoHeapSizing,
1536 "attempt heap expansion",
1537 ergo_format_reason("capacity lower than "
1538 "min desired capacity after Full GC")
1539 ergo_format_byte("capacity")
1540 ergo_format_byte("occupancy")
1541 ergo_format_byte_perc("min desired capacity"),
1542 capacity_after_gc, used_after_gc,
1543 minimum_desired_capacity, (double) MinHeapFreeRatio);
1544 expand(expand_bytes);
1545
1546 // No expansion, now see if we want to shrink
1547 } else if (capacity_after_gc > maximum_desired_capacity) {
1548 // Capacity too large, compute shrinking size
1549 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1550 ergo_verbose4(ErgoHeapSizing,
1551 "attempt heap shrinking",
1552 ergo_format_reason("capacity higher than "
1553 "max desired capacity after Full GC")
1554 ergo_format_byte("capacity")
1555 ergo_format_byte("occupancy")
1556 ergo_format_byte_perc("max desired capacity"),
1557 capacity_after_gc, used_after_gc,
1558 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1559 shrink(shrink_bytes);
1560 }
1561 }
1562
1563 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1564 AllocationContext_t context,
1565 bool do_gc,
1566 bool clear_all_soft_refs,
1567 bool expect_null_mutator_alloc_region,
1568 bool* gc_succeeded) {
1569 *gc_succeeded = true;
1570 // Let's attempt the allocation first.
1571 HeapWord* result =
1572 attempt_allocation_at_safepoint(word_size,
1573 context,
1574 expect_null_mutator_alloc_region);
1575 if (result != NULL) {
1576 assert(*gc_succeeded, "sanity");
1577 return result;
1578 }
1579
1580 // In a G1 heap, we're supposed to keep allocation from failing by
1581 // incremental pauses. Therefore, at least for now, we'll favor
1582 // expansion over collection. (This might change in the future if we can
1583 // do something smarter than full collection to satisfy a failed alloc.)
1584 result = expand_and_allocate(word_size, context);
1585 if (result != NULL) {
1586 assert(*gc_succeeded, "sanity");
1587 return result;
1588 }
1589
1590 if (do_gc) {
1591 // Expansion didn't work, we'll try to do a Full GC.
1592 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1593 clear_all_soft_refs);
1594 }
1595
1596 return NULL;
1597 }
1598
1599 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1600 AllocationContext_t context,
1601 bool* succeeded) {
1602 assert_at_safepoint(true /* should_be_vm_thread */);
1603
1604 // Attempts to allocate followed by Full GC.
1605 HeapWord* result =
1606 satisfy_failed_allocation_helper(word_size,
1607 context,
1608 true, /* do_gc */
1609 false, /* clear_all_soft_refs */
1610 false, /* expect_null_mutator_alloc_region */
1611 succeeded);
1612
1613 if (result != NULL || !*succeeded) {
1614 return result;
1615 }
1616
1617 // Attempts to allocate followed by Full GC that will collect all soft references.
1618 result = satisfy_failed_allocation_helper(word_size,
1619 context,
1620 true, /* do_gc */
1621 true, /* clear_all_soft_refs */
1622 true, /* expect_null_mutator_alloc_region */
1623 succeeded);
1624
1625 if (result != NULL || !*succeeded) {
1626 return result;
1627 }
1628
1629 // Attempts to allocate, no GC
1630 result = satisfy_failed_allocation_helper(word_size,
1631 context,
1632 false, /* do_gc */
1633 false, /* clear_all_soft_refs */
1634 true, /* expect_null_mutator_alloc_region */
1635 succeeded);
1636
1637 if (result != NULL) {
1638 assert(*succeeded, "sanity");
1639 return result;
1640 }
1641
1642 assert(!collector_policy()->should_clear_all_soft_refs(),
1643 "Flag should have been handled and cleared prior to this point");
1644
1645 // What else? We might try synchronous finalization later. If the total
1646 // space available is large enough for the allocation, then a more
1647 // complete compaction phase than we've tried so far might be
1648 // appropriate.
1649 assert(*succeeded, "sanity");
1650 return NULL;
1651 }
1652
1653 // Attempting to expand the heap sufficiently
1654 // to support an allocation of the given "word_size". If
1655 // successful, perform the allocation and return the address of the
1656 // allocated block, or else "NULL".
1657
1658 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1659 assert_at_safepoint(true /* should_be_vm_thread */);
1660
1661 verify_region_sets_optional();
1662
1663 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1664 ergo_verbose1(ErgoHeapSizing,
1665 "attempt heap expansion",
1666 ergo_format_reason("allocation request failed")
1667 ergo_format_byte("allocation request"),
1668 word_size * HeapWordSize);
1669 if (expand(expand_bytes)) {
1670 _hrm.verify_optional();
1671 verify_region_sets_optional();
1672 return attempt_allocation_at_safepoint(word_size,
1673 context,
1674 false /* expect_null_mutator_alloc_region */);
1675 }
1676 return NULL;
1677 }
1678
1679 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1680 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1681 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1682 HeapRegion::GrainBytes);
1683 ergo_verbose2(ErgoHeapSizing,
1684 "expand the heap",
1685 ergo_format_byte("requested expansion amount")
1686 ergo_format_byte("attempted expansion amount"),
1687 expand_bytes, aligned_expand_bytes);
1688
1689 if (is_maximal_no_gc()) {
1690 ergo_verbose0(ErgoHeapSizing,
1691 "did not expand the heap",
1692 ergo_format_reason("heap already fully expanded"));
1693 return false;
1694 }
1695
1696 double expand_heap_start_time_sec = os::elapsedTime();
1697 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1698 assert(regions_to_expand > 0, "Must expand by at least one region");
1699
1700 uint expanded_by = _hrm.expand_by(regions_to_expand);
1701 if (expand_time_ms != NULL) {
1702 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1703 }
1704
1705 if (expanded_by > 0) {
1706 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1707 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1708 g1_policy()->record_new_heap_size(num_regions());
1709 } else {
1710 ergo_verbose0(ErgoHeapSizing,
1711 "did not expand the heap",
1712 ergo_format_reason("heap expansion operation failed"));
1713 // The expansion of the virtual storage space was unsuccessful.
1714 // Let's see if it was because we ran out of swap.
1715 if (G1ExitOnExpansionFailure &&
1716 _hrm.available() >= regions_to_expand) {
1717 // We had head room...
1718 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1719 }
1720 }
1721 return regions_to_expand > 0;
1722 }
1723
1724 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1725 size_t aligned_shrink_bytes =
1726 ReservedSpace::page_align_size_down(shrink_bytes);
1727 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1728 HeapRegion::GrainBytes);
1729 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1730
1731 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1732 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1733
1734 ergo_verbose3(ErgoHeapSizing,
1735 "shrink the heap",
1736 ergo_format_byte("requested shrinking amount")
1737 ergo_format_byte("aligned shrinking amount")
1738 ergo_format_byte("attempted shrinking amount"),
1739 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1740 if (num_regions_removed > 0) {
1741 g1_policy()->record_new_heap_size(num_regions());
1742 } else {
1743 ergo_verbose0(ErgoHeapSizing,
1744 "did not shrink the heap",
1745 ergo_format_reason("heap shrinking operation failed"));
1746 }
1747 }
1748
1749 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1750 verify_region_sets_optional();
1751
1752 // We should only reach here at the end of a Full GC which means we
1753 // should not not be holding to any GC alloc regions. The method
1754 // below will make sure of that and do any remaining clean up.
1755 _allocator->abandon_gc_alloc_regions();
1756
1757 // Instead of tearing down / rebuilding the free lists here, we
1758 // could instead use the remove_all_pending() method on free_list to
1759 // remove only the ones that we need to remove.
1760 tear_down_region_sets(true /* free_list_only */);
1761 shrink_helper(shrink_bytes);
1762 rebuild_region_sets(true /* free_list_only */);
1763
1764 _hrm.verify_optional();
1765 verify_region_sets_optional();
1766 }
1767
1768 // Public methods.
1769
1770 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1771 CollectedHeap(),
1772 _g1_policy(policy_),
1773 _dirty_card_queue_set(false),
1774 _is_alive_closure_cm(this),
1775 _is_alive_closure_stw(this),
1776 _ref_processor_cm(NULL),
1777 _ref_processor_stw(NULL),
1778 _bot_shared(NULL),
1779 _cg1r(NULL),
1780 _g1mm(NULL),
1781 _refine_cte_cl(NULL),
1782 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1783 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1784 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1785 _humongous_reclaim_candidates(),
1786 _has_humongous_reclaim_candidates(false),
1787 _archive_allocator(NULL),
1788 _free_regions_coming(false),
1789 _young_list(new YoungList(this)),
1790 _gc_time_stamp(0),
1791 _summary_bytes_used(0),
1792 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1793 _old_evac_stats(OldPLABSize, PLABWeight),
1794 _expand_heap_after_alloc_failure(true),
1795 _old_marking_cycles_started(0),
1796 _old_marking_cycles_completed(0),
1797 _heap_summary_sent(false),
1798 _in_cset_fast_test(),
1799 _dirty_cards_region_list(NULL),
1800 _worker_cset_start_region(NULL),
1801 _worker_cset_start_region_time_stamp(NULL),
1802 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1803 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1804 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1805 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1806
1807 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1808 /* are_GC_task_threads */true,
1809 /* are_ConcurrentGC_threads */false);
1810 _workers->initialize_workers();
1811
1812 _allocator = G1Allocator::create_allocator(this);
1813 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1814
1815 // Override the default _filler_array_max_size so that no humongous filler
1816 // objects are created.
1817 _filler_array_max_size = _humongous_object_threshold_in_words;
1818
1819 uint n_queues = ParallelGCThreads;
1820 _task_queues = new RefToScanQueueSet(n_queues);
1821
1822 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1823 assert(n_rem_sets > 0, "Invariant.");
1824
1825 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1826 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1827 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1828
1829 for (uint i = 0; i < n_queues; i++) {
1830 RefToScanQueue* q = new RefToScanQueue();
1831 q->initialize();
1832 _task_queues->register_queue(i, q);
1833 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1834 }
1835 clear_cset_start_regions();
1836
1837 // Initialize the G1EvacuationFailureALot counters and flags.
1838 NOT_PRODUCT(reset_evacuation_should_fail();)
1839
1840 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1841 }
1842
1843 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1844 size_t size,
1845 size_t translation_factor) {
1846 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1847 // Allocate a new reserved space, preferring to use large pages.
1848 ReservedSpace rs(size, preferred_page_size);
1849 G1RegionToSpaceMapper* result =
1850 G1RegionToSpaceMapper::create_mapper(rs,
1851 size,
1852 rs.alignment(),
1853 HeapRegion::GrainBytes,
1854 translation_factor,
1855 mtGC);
1856 if (TracePageSizes) {
1857 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1858 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1859 }
1860 return result;
1861 }
1862
1863 jint G1CollectedHeap::initialize() {
1864 CollectedHeap::pre_initialize();
1865 os::enable_vtime();
1866
1867 G1Log::init();
1868
1869 // Necessary to satisfy locking discipline assertions.
1870
1871 MutexLocker x(Heap_lock);
1872
1873 // We have to initialize the printer before committing the heap, as
1874 // it will be used then.
1875 _hr_printer.set_active(G1PrintHeapRegions);
1876
1877 // While there are no constraints in the GC code that HeapWordSize
1878 // be any particular value, there are multiple other areas in the
1879 // system which believe this to be true (e.g. oop->object_size in some
1880 // cases incorrectly returns the size in wordSize units rather than
1881 // HeapWordSize).
1882 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1883
1884 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1885 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1886 size_t heap_alignment = collector_policy()->heap_alignment();
1887
1888 // Ensure that the sizes are properly aligned.
1889 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1890 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1891 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1892
1893 _refine_cte_cl = new RefineCardTableEntryClosure();
1894
1895 jint ecode = JNI_OK;
1896 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1897 if (_cg1r == NULL) {
1898 return ecode;
1899 }
1900
1901 // Reserve the maximum.
1902
1903 // When compressed oops are enabled, the preferred heap base
1904 // is calculated by subtracting the requested size from the
1905 // 32Gb boundary and using the result as the base address for
1906 // heap reservation. If the requested size is not aligned to
1907 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1908 // into the ReservedHeapSpace constructor) then the actual
1909 // base of the reserved heap may end up differing from the
1910 // address that was requested (i.e. the preferred heap base).
1911 // If this happens then we could end up using a non-optimal
1912 // compressed oops mode.
1913
1914 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1915 heap_alignment);
1916
1917 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1918
1919 // Create the barrier set for the entire reserved region.
1920 G1SATBCardTableLoggingModRefBS* bs
1921 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1922 bs->initialize();
1923 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1924 set_barrier_set(bs);
1925
1926 // Also create a G1 rem set.
1927 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1928
1929 // Carve out the G1 part of the heap.
1930
1931 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1932 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1933 G1RegionToSpaceMapper* heap_storage =
1934 G1RegionToSpaceMapper::create_mapper(g1_rs,
1935 g1_rs.size(),
1936 page_size,
1937 HeapRegion::GrainBytes,
1938 1,
1939 mtJavaHeap);
1940 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1941 max_byte_size, page_size,
1942 heap_rs.base(),
1943 heap_rs.size());
1944 heap_storage->set_mapping_changed_listener(&_listener);
1945
1946 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1947 G1RegionToSpaceMapper* bot_storage =
1948 create_aux_memory_mapper("Block offset table",
1949 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1950 G1BlockOffsetSharedArray::heap_map_factor());
1951
1952 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1953 G1RegionToSpaceMapper* cardtable_storage =
1954 create_aux_memory_mapper("Card table",
1955 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1956 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1957
1958 G1RegionToSpaceMapper* card_counts_storage =
1959 create_aux_memory_mapper("Card counts table",
1960 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1961 G1CardCounts::heap_map_factor());
1962
1963 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1964 G1RegionToSpaceMapper* prev_bitmap_storage =
1965 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1966 G1RegionToSpaceMapper* next_bitmap_storage =
1967 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1968
1969 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1970 g1_barrier_set()->initialize(cardtable_storage);
1971 // Do later initialization work for concurrent refinement.
1972 _cg1r->init(card_counts_storage);
1973
1974 // 6843694 - ensure that the maximum region index can fit
1975 // in the remembered set structures.
1976 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1977 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1978
1979 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1980 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1981 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1982 "too many cards per region");
1983
1984 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1985
1986 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1987
1988 {
1989 HeapWord* start = _hrm.reserved().start();
1990 HeapWord* end = _hrm.reserved().end();
1991 size_t granularity = HeapRegion::GrainBytes;
1992
1993 _in_cset_fast_test.initialize(start, end, granularity);
1994 _humongous_reclaim_candidates.initialize(start, end, granularity);
1995 }
1996
1997 // Create the ConcurrentMark data structure and thread.
1998 // (Must do this late, so that "max_regions" is defined.)
1999 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2000 if (_cm == NULL || !_cm->completed_initialization()) {
2001 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2002 return JNI_ENOMEM;
2003 }
2004 _cmThread = _cm->cmThread();
2005
2006 // Initialize the from_card cache structure of HeapRegionRemSet.
2007 HeapRegionRemSet::init_heap(max_regions());
2008
2009 // Now expand into the initial heap size.
2010 if (!expand(init_byte_size)) {
2011 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2012 return JNI_ENOMEM;
2013 }
2014
2015 // Perform any initialization actions delegated to the policy.
2016 g1_policy()->init();
2017
2018 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2019 SATB_Q_FL_lock,
2020 G1SATBProcessCompletedThreshold,
2021 Shared_SATB_Q_lock);
2022
2023 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2024 DirtyCardQ_CBL_mon,
2025 DirtyCardQ_FL_lock,
2026 concurrent_g1_refine()->yellow_zone(),
2027 concurrent_g1_refine()->red_zone(),
2028 Shared_DirtyCardQ_lock);
2029
2030 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2031 DirtyCardQ_CBL_mon,
2032 DirtyCardQ_FL_lock,
2033 -1, // never trigger processing
2034 -1, // no limit on length
2035 Shared_DirtyCardQ_lock,
2036 &JavaThread::dirty_card_queue_set());
2037
2038 // Here we allocate the dummy HeapRegion that is required by the
2039 // G1AllocRegion class.
2040 HeapRegion* dummy_region = _hrm.get_dummy_region();
2041
2042 // We'll re-use the same region whether the alloc region will
2043 // require BOT updates or not and, if it doesn't, then a non-young
2044 // region will complain that it cannot support allocations without
2045 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2046 dummy_region->set_eden();
2047 // Make sure it's full.
2048 dummy_region->set_top(dummy_region->end());
2049 G1AllocRegion::setup(this, dummy_region);
2050
2051 _allocator->init_mutator_alloc_region();
2052
2053 // Do create of the monitoring and management support so that
2054 // values in the heap have been properly initialized.
2055 _g1mm = new G1MonitoringSupport(this);
2056
2057 G1StringDedup::initialize();
2058
2059 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2060 for (uint i = 0; i < ParallelGCThreads; i++) {
2061 new (&_preserved_objs[i]) OopAndMarkOopStack();
2062 }
2063
2064 return JNI_OK;
2065 }
2066
2067 void G1CollectedHeap::stop() {
2068 // Stop all concurrent threads. We do this to make sure these threads
2069 // do not continue to execute and access resources (e.g. gclog_or_tty)
2070 // that are destroyed during shutdown.
2071 _cg1r->stop();
2072 _cmThread->stop();
2073 if (G1StringDedup::is_enabled()) {
2074 G1StringDedup::stop();
2075 }
2076 }
2077
2078 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2079 return HeapRegion::max_region_size();
2080 }
2081
2082 void G1CollectedHeap::post_initialize() {
2083 CollectedHeap::post_initialize();
2084 ref_processing_init();
2085 }
2086
2087 void G1CollectedHeap::ref_processing_init() {
2088 // Reference processing in G1 currently works as follows:
2089 //
2090 // * There are two reference processor instances. One is
2091 // used to record and process discovered references
2092 // during concurrent marking; the other is used to
2093 // record and process references during STW pauses
2094 // (both full and incremental).
2095 // * Both ref processors need to 'span' the entire heap as
2096 // the regions in the collection set may be dotted around.
2097 //
2098 // * For the concurrent marking ref processor:
2099 // * Reference discovery is enabled at initial marking.
2100 // * Reference discovery is disabled and the discovered
2101 // references processed etc during remarking.
2102 // * Reference discovery is MT (see below).
2103 // * Reference discovery requires a barrier (see below).
2104 // * Reference processing may or may not be MT
2105 // (depending on the value of ParallelRefProcEnabled
2106 // and ParallelGCThreads).
2107 // * A full GC disables reference discovery by the CM
2108 // ref processor and abandons any entries on it's
2109 // discovered lists.
2110 //
2111 // * For the STW processor:
2112 // * Non MT discovery is enabled at the start of a full GC.
2113 // * Processing and enqueueing during a full GC is non-MT.
2114 // * During a full GC, references are processed after marking.
2115 //
2116 // * Discovery (may or may not be MT) is enabled at the start
2117 // of an incremental evacuation pause.
2118 // * References are processed near the end of a STW evacuation pause.
2119 // * For both types of GC:
2120 // * Discovery is atomic - i.e. not concurrent.
2121 // * Reference discovery will not need a barrier.
2122
2123 MemRegion mr = reserved_region();
2124
2125 // Concurrent Mark ref processor
2126 _ref_processor_cm =
2127 new ReferenceProcessor(mr, // span
2128 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2129 // mt processing
2130 ParallelGCThreads,
2131 // degree of mt processing
2132 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2133 // mt discovery
2134 MAX2(ParallelGCThreads, ConcGCThreads),
2135 // degree of mt discovery
2136 false,
2137 // Reference discovery is not atomic
2138 &_is_alive_closure_cm);
2139 // is alive closure
2140 // (for efficiency/performance)
2141
2142 // STW ref processor
2143 _ref_processor_stw =
2144 new ReferenceProcessor(mr, // span
2145 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2146 // mt processing
2147 ParallelGCThreads,
2148 // degree of mt processing
2149 (ParallelGCThreads > 1),
2150 // mt discovery
2151 ParallelGCThreads,
2152 // degree of mt discovery
2153 true,
2154 // Reference discovery is atomic
2155 &_is_alive_closure_stw);
2156 // is alive closure
2157 // (for efficiency/performance)
2158 }
2159
2160 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2161 return g1_policy();
2162 }
2163
2164 size_t G1CollectedHeap::capacity() const {
2165 return _hrm.length() * HeapRegion::GrainBytes;
2166 }
2167
2168 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2169 hr->reset_gc_time_stamp();
2170 }
2171
2172 #ifndef PRODUCT
2173
2174 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2175 private:
2176 unsigned _gc_time_stamp;
2177 bool _failures;
2178
2179 public:
2180 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2181 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2182
2183 virtual bool doHeapRegion(HeapRegion* hr) {
2184 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2185 if (_gc_time_stamp != region_gc_time_stamp) {
2186 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2187 "expected %d", HR_FORMAT_PARAMS(hr),
2188 region_gc_time_stamp, _gc_time_stamp);
2189 _failures = true;
2190 }
2191 return false;
2192 }
2193
2194 bool failures() { return _failures; }
2195 };
2196
2197 void G1CollectedHeap::check_gc_time_stamps() {
2198 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2199 heap_region_iterate(&cl);
2200 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2201 }
2202 #endif // PRODUCT
2203
2204 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2205 _cg1r->hot_card_cache()->drain(cl, worker_i);
2206 }
2207
2208 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2209 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2210 size_t n_completed_buffers = 0;
2211 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2212 n_completed_buffers++;
2213 }
2214 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2215 dcqs.clear_n_completed_buffers();
2216 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2217 }
2218
2219 // Computes the sum of the storage used by the various regions.
2220 size_t G1CollectedHeap::used() const {
2221 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2222 if (_archive_allocator != NULL) {
2223 result += _archive_allocator->used();
2224 }
2225 return result;
2226 }
2227
2228 size_t G1CollectedHeap::used_unlocked() const {
2229 return _summary_bytes_used;
2230 }
2231
2232 class SumUsedClosure: public HeapRegionClosure {
2233 size_t _used;
2234 public:
2235 SumUsedClosure() : _used(0) {}
2236 bool doHeapRegion(HeapRegion* r) {
2237 _used += r->used();
2238 return false;
2239 }
2240 size_t result() { return _used; }
2241 };
2242
2243 size_t G1CollectedHeap::recalculate_used() const {
2244 double recalculate_used_start = os::elapsedTime();
2245
2246 SumUsedClosure blk;
2247 heap_region_iterate(&blk);
2248
2249 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2250 return blk.result();
2251 }
2252
2253 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2254 switch (cause) {
2255 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2256 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2257 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2258 case GCCause::_g1_humongous_allocation: return true;
2259 case GCCause::_update_allocation_context_stats_inc: return true;
2260 case GCCause::_wb_conc_mark: return true;
2261 default: return false;
2262 }
2263 }
2264
2265 #ifndef PRODUCT
2266 void G1CollectedHeap::allocate_dummy_regions() {
2267 // Let's fill up most of the region
2268 size_t word_size = HeapRegion::GrainWords - 1024;
2269 // And as a result the region we'll allocate will be humongous.
2270 guarantee(is_humongous(word_size), "sanity");
2271
2272 // _filler_array_max_size is set to humongous object threshold
2273 // but temporarily change it to use CollectedHeap::fill_with_object().
2274 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2275
2276 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2277 // Let's use the existing mechanism for the allocation
2278 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2279 AllocationContext::system());
2280 if (dummy_obj != NULL) {
2281 MemRegion mr(dummy_obj, word_size);
2282 CollectedHeap::fill_with_object(mr);
2283 } else {
2284 // If we can't allocate once, we probably cannot allocate
2285 // again. Let's get out of the loop.
2286 break;
2287 }
2288 }
2289 }
2290 #endif // !PRODUCT
2291
2292 void G1CollectedHeap::increment_old_marking_cycles_started() {
2293 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2294 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2295 "Wrong marking cycle count (started: %d, completed: %d)",
2296 _old_marking_cycles_started, _old_marking_cycles_completed);
2297
2298 _old_marking_cycles_started++;
2299 }
2300
2301 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2302 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2303
2304 // We assume that if concurrent == true, then the caller is a
2305 // concurrent thread that was joined the Suspendible Thread
2306 // Set. If there's ever a cheap way to check this, we should add an
2307 // assert here.
2308
2309 // Given that this method is called at the end of a Full GC or of a
2310 // concurrent cycle, and those can be nested (i.e., a Full GC can
2311 // interrupt a concurrent cycle), the number of full collections
2312 // completed should be either one (in the case where there was no
2313 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2314 // behind the number of full collections started.
2315
2316 // This is the case for the inner caller, i.e. a Full GC.
2317 assert(concurrent ||
2318 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2319 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2320 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2321 "is inconsistent with _old_marking_cycles_completed = %u",
2322 _old_marking_cycles_started, _old_marking_cycles_completed);
2323
2324 // This is the case for the outer caller, i.e. the concurrent cycle.
2325 assert(!concurrent ||
2326 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2327 "for outer caller (concurrent cycle): "
2328 "_old_marking_cycles_started = %u "
2329 "is inconsistent with _old_marking_cycles_completed = %u",
2330 _old_marking_cycles_started, _old_marking_cycles_completed);
2331
2332 _old_marking_cycles_completed += 1;
2333
2334 // We need to clear the "in_progress" flag in the CM thread before
2335 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2336 // is set) so that if a waiter requests another System.gc() it doesn't
2337 // incorrectly see that a marking cycle is still in progress.
2338 if (concurrent) {
2339 _cmThread->set_idle();
2340 }
2341
2342 // This notify_all() will ensure that a thread that called
2343 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2344 // and it's waiting for a full GC to finish will be woken up. It is
2345 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2346 FullGCCount_lock->notify_all();
2347 }
2348
2349 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2350 GCIdMarkAndRestore conc_gc_id_mark;
2351 collector_state()->set_concurrent_cycle_started(true);
2352 _gc_timer_cm->register_gc_start(start_time);
2353
2354 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2355 trace_heap_before_gc(_gc_tracer_cm);
2356 _cmThread->set_gc_id(GCId::current());
2357 }
2358
2359 void G1CollectedHeap::register_concurrent_cycle_end() {
2360 if (collector_state()->concurrent_cycle_started()) {
2361 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2362 if (_cm->has_aborted()) {
2363 _gc_tracer_cm->report_concurrent_mode_failure();
2364 }
2365
2366 _gc_timer_cm->register_gc_end();
2367 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2368
2369 // Clear state variables to prepare for the next concurrent cycle.
2370 collector_state()->set_concurrent_cycle_started(false);
2371 _heap_summary_sent = false;
2372 }
2373 }
2374
2375 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2376 if (collector_state()->concurrent_cycle_started()) {
2377 // This function can be called when:
2378 // the cleanup pause is run
2379 // the concurrent cycle is aborted before the cleanup pause.
2380 // the concurrent cycle is aborted after the cleanup pause,
2381 // but before the concurrent cycle end has been registered.
2382 // Make sure that we only send the heap information once.
2383 if (!_heap_summary_sent) {
2384 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2385 trace_heap_after_gc(_gc_tracer_cm);
2386 _heap_summary_sent = true;
2387 }
2388 }
2389 }
2390
2391 void G1CollectedHeap::collect(GCCause::Cause cause) {
2392 assert_heap_not_locked();
2393
2394 uint gc_count_before;
2395 uint old_marking_count_before;
2396 uint full_gc_count_before;
2397 bool retry_gc;
2398
2399 do {
2400 retry_gc = false;
2401
2402 {
2403 MutexLocker ml(Heap_lock);
2404
2405 // Read the GC count while holding the Heap_lock
2406 gc_count_before = total_collections();
2407 full_gc_count_before = total_full_collections();
2408 old_marking_count_before = _old_marking_cycles_started;
2409 }
2410
2411 if (should_do_concurrent_full_gc(cause)) {
2412 // Schedule an initial-mark evacuation pause that will start a
2413 // concurrent cycle. We're setting word_size to 0 which means that
2414 // we are not requesting a post-GC allocation.
2415 VM_G1IncCollectionPause op(gc_count_before,
2416 0, /* word_size */
2417 true, /* should_initiate_conc_mark */
2418 g1_policy()->max_pause_time_ms(),
2419 cause);
2420 op.set_allocation_context(AllocationContext::current());
2421
2422 VMThread::execute(&op);
2423 if (!op.pause_succeeded()) {
2424 if (old_marking_count_before == _old_marking_cycles_started) {
2425 retry_gc = op.should_retry_gc();
2426 } else {
2427 // A Full GC happened while we were trying to schedule the
2428 // initial-mark GC. No point in starting a new cycle given
2429 // that the whole heap was collected anyway.
2430 }
2431
2432 if (retry_gc) {
2433 if (GC_locker::is_active_and_needs_gc()) {
2434 GC_locker::stall_until_clear();
2435 }
2436 }
2437 }
2438 } else {
2439 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2440 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2441
2442 // Schedule a standard evacuation pause. We're setting word_size
2443 // to 0 which means that we are not requesting a post-GC allocation.
2444 VM_G1IncCollectionPause op(gc_count_before,
2445 0, /* word_size */
2446 false, /* should_initiate_conc_mark */
2447 g1_policy()->max_pause_time_ms(),
2448 cause);
2449 VMThread::execute(&op);
2450 } else {
2451 // Schedule a Full GC.
2452 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2453 VMThread::execute(&op);
2454 }
2455 }
2456 } while (retry_gc);
2457 }
2458
2459 bool G1CollectedHeap::is_in(const void* p) const {
2460 if (_hrm.reserved().contains(p)) {
2461 // Given that we know that p is in the reserved space,
2462 // heap_region_containing() should successfully
2463 // return the containing region.
2464 HeapRegion* hr = heap_region_containing(p);
2465 return hr->is_in(p);
2466 } else {
2467 return false;
2468 }
2469 }
2470
2471 #ifdef ASSERT
2472 bool G1CollectedHeap::is_in_exact(const void* p) const {
2473 bool contains = reserved_region().contains(p);
2474 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2475 if (contains && available) {
2476 return true;
2477 } else {
2478 return false;
2479 }
2480 }
2481 #endif
2482
2483 bool G1CollectedHeap::obj_in_cs(oop obj) {
2484 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2485 return r != NULL && r->in_collection_set();
2486 }
2487
2488 // Iteration functions.
2489
2490 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2491
2492 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2493 ExtendedOopClosure* _cl;
2494 public:
2495 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2496 bool doHeapRegion(HeapRegion* r) {
2497 if (!r->is_continues_humongous()) {
2498 r->oop_iterate(_cl);
2499 }
2500 return false;
2501 }
2502 };
2503
2504 // Iterates an ObjectClosure over all objects within a HeapRegion.
2505
2506 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2507 ObjectClosure* _cl;
2508 public:
2509 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2510 bool doHeapRegion(HeapRegion* r) {
2511 if (!r->is_continues_humongous()) {
2512 r->object_iterate(_cl);
2513 }
2514 return false;
2515 }
2516 };
2517
2518 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2519 IterateObjectClosureRegionClosure blk(cl);
2520 heap_region_iterate(&blk);
2521 }
2522
2523 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2524 _hrm.iterate(cl);
2525 }
2526
2527 void
2528 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2529 uint worker_id,
2530 HeapRegionClaimer *hrclaimer,
2531 bool concurrent) const {
2532 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2533 }
2534
2535 // Clear the cached CSet starting regions and (more importantly)
2536 // the time stamps. Called when we reset the GC time stamp.
2537 void G1CollectedHeap::clear_cset_start_regions() {
2538 assert(_worker_cset_start_region != NULL, "sanity");
2539 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2540
2541 for (uint i = 0; i < ParallelGCThreads; i++) {
2542 _worker_cset_start_region[i] = NULL;
2543 _worker_cset_start_region_time_stamp[i] = 0;
2544 }
2545 }
2546
2547 // Given the id of a worker, obtain or calculate a suitable
2548 // starting region for iterating over the current collection set.
2549 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2550 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2551
2552 HeapRegion* result = NULL;
2553 unsigned gc_time_stamp = get_gc_time_stamp();
2554
2555 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2556 // Cached starting region for current worker was set
2557 // during the current pause - so it's valid.
2558 // Note: the cached starting heap region may be NULL
2559 // (when the collection set is empty).
2560 result = _worker_cset_start_region[worker_i];
2561 assert(result == NULL || result->in_collection_set(), "sanity");
2562 return result;
2563 }
2564
2565 // The cached entry was not valid so let's calculate
2566 // a suitable starting heap region for this worker.
2567
2568 // We want the parallel threads to start their collection
2569 // set iteration at different collection set regions to
2570 // avoid contention.
2571 // If we have:
2572 // n collection set regions
2573 // p threads
2574 // Then thread t will start at region floor ((t * n) / p)
2575
2576 result = g1_policy()->collection_set();
2577 uint cs_size = g1_policy()->cset_region_length();
2578 uint active_workers = workers()->active_workers();
2579
2580 uint end_ind = (cs_size * worker_i) / active_workers;
2581 uint start_ind = 0;
2582
2583 if (worker_i > 0 &&
2584 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2585 // Previous workers starting region is valid
2586 // so let's iterate from there
2587 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2588 result = _worker_cset_start_region[worker_i - 1];
2589 }
2590
2591 for (uint i = start_ind; i < end_ind; i++) {
2592 result = result->next_in_collection_set();
2593 }
2594
2595 // Note: the calculated starting heap region may be NULL
2596 // (when the collection set is empty).
2597 assert(result == NULL || result->in_collection_set(), "sanity");
2598 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2599 "should be updated only once per pause");
2600 _worker_cset_start_region[worker_i] = result;
2601 OrderAccess::storestore();
2602 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2603 return result;
2604 }
2605
2606 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2607 HeapRegion* r = g1_policy()->collection_set();
2608 while (r != NULL) {
2609 HeapRegion* next = r->next_in_collection_set();
2610 if (cl->doHeapRegion(r)) {
2611 cl->incomplete();
2612 return;
2613 }
2614 r = next;
2615 }
2616 }
2617
2618 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2619 HeapRegionClosure *cl) {
2620 if (r == NULL) {
2621 // The CSet is empty so there's nothing to do.
2622 return;
2623 }
2624
2625 assert(r->in_collection_set(),
2626 "Start region must be a member of the collection set.");
2627 HeapRegion* cur = r;
2628 while (cur != NULL) {
2629 HeapRegion* next = cur->next_in_collection_set();
2630 if (cl->doHeapRegion(cur) && false) {
2631 cl->incomplete();
2632 return;
2633 }
2634 cur = next;
2635 }
2636 cur = g1_policy()->collection_set();
2637 while (cur != r) {
2638 HeapRegion* next = cur->next_in_collection_set();
2639 if (cl->doHeapRegion(cur) && false) {
2640 cl->incomplete();
2641 return;
2642 }
2643 cur = next;
2644 }
2645 }
2646
2647 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2648 HeapRegion* result = _hrm.next_region_in_heap(from);
2649 while (result != NULL && result->is_pinned()) {
2650 result = _hrm.next_region_in_heap(result);
2651 }
2652 return result;
2653 }
2654
2655 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2656 HeapRegion* hr = heap_region_containing(addr);
2657 return hr->block_start(addr);
2658 }
2659
2660 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2661 HeapRegion* hr = heap_region_containing(addr);
2662 return hr->block_size(addr);
2663 }
2664
2665 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2666 HeapRegion* hr = heap_region_containing(addr);
2667 return hr->block_is_obj(addr);
2668 }
2669
2670 bool G1CollectedHeap::supports_tlab_allocation() const {
2671 return true;
2672 }
2673
2674 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2675 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2676 }
2677
2678 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2679 return young_list()->eden_used_bytes();
2680 }
2681
2682 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2683 // must be equal to the humongous object limit.
2684 size_t G1CollectedHeap::max_tlab_size() const {
2685 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2686 }
2687
2688 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2689 AllocationContext_t context = AllocationContext::current();
2690 return _allocator->unsafe_max_tlab_alloc(context);
2691 }
2692
2693 size_t G1CollectedHeap::max_capacity() const {
2694 return _hrm.reserved().byte_size();
2695 }
2696
2697 jlong G1CollectedHeap::millis_since_last_gc() {
2698 // assert(false, "NYI");
2699 return 0;
2700 }
2701
2702 void G1CollectedHeap::prepare_for_verify() {
2703 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2704 ensure_parsability(false);
2705 }
2706 g1_rem_set()->prepare_for_verify();
2707 }
2708
2709 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2710 VerifyOption vo) {
2711 switch (vo) {
2712 case VerifyOption_G1UsePrevMarking:
2713 return hr->obj_allocated_since_prev_marking(obj);
2714 case VerifyOption_G1UseNextMarking:
2715 return hr->obj_allocated_since_next_marking(obj);
2716 case VerifyOption_G1UseMarkWord:
2717 return false;
2718 default:
2719 ShouldNotReachHere();
2720 }
2721 return false; // keep some compilers happy
2722 }
2723
2724 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2725 switch (vo) {
2726 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2727 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2728 case VerifyOption_G1UseMarkWord: return NULL;
2729 default: ShouldNotReachHere();
2730 }
2731 return NULL; // keep some compilers happy
2732 }
2733
2734 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2735 switch (vo) {
2736 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2737 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2738 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2739 default: ShouldNotReachHere();
2740 }
2741 return false; // keep some compilers happy
2742 }
2743
2744 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2745 switch (vo) {
2746 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2747 case VerifyOption_G1UseNextMarking: return "NTAMS";
2748 case VerifyOption_G1UseMarkWord: return "NONE";
2749 default: ShouldNotReachHere();
2750 }
2751 return NULL; // keep some compilers happy
2752 }
2753
2754 class VerifyRootsClosure: public OopClosure {
2755 private:
2756 G1CollectedHeap* _g1h;
2757 VerifyOption _vo;
2758 bool _failures;
2759 public:
2760 // _vo == UsePrevMarking -> use "prev" marking information,
2761 // _vo == UseNextMarking -> use "next" marking information,
2762 // _vo == UseMarkWord -> use mark word from object header.
2763 VerifyRootsClosure(VerifyOption vo) :
2764 _g1h(G1CollectedHeap::heap()),
2765 _vo(vo),
2766 _failures(false) { }
2767
2768 bool failures() { return _failures; }
2769
2770 template <class T> void do_oop_nv(T* p) {
2771 T heap_oop = oopDesc::load_heap_oop(p);
2772 if (!oopDesc::is_null(heap_oop)) {
2773 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2774 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2775 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2776 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2777 if (_vo == VerifyOption_G1UseMarkWord) {
2778 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2779 }
2780 obj->print_on(gclog_or_tty);
2781 _failures = true;
2782 }
2783 }
2784 }
2785
2786 void do_oop(oop* p) { do_oop_nv(p); }
2787 void do_oop(narrowOop* p) { do_oop_nv(p); }
2788 };
2789
2790 class G1VerifyCodeRootOopClosure: public OopClosure {
2791 G1CollectedHeap* _g1h;
2792 OopClosure* _root_cl;
2793 nmethod* _nm;
2794 VerifyOption _vo;
2795 bool _failures;
2796
2797 template <class T> void do_oop_work(T* p) {
2798 // First verify that this root is live
2799 _root_cl->do_oop(p);
2800
2801 if (!G1VerifyHeapRegionCodeRoots) {
2802 // We're not verifying the code roots attached to heap region.
2803 return;
2804 }
2805
2806 // Don't check the code roots during marking verification in a full GC
2807 if (_vo == VerifyOption_G1UseMarkWord) {
2808 return;
2809 }
2810
2811 // Now verify that the current nmethod (which contains p) is
2812 // in the code root list of the heap region containing the
2813 // object referenced by p.
2814
2815 T heap_oop = oopDesc::load_heap_oop(p);
2816 if (!oopDesc::is_null(heap_oop)) {
2817 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2818
2819 // Now fetch the region containing the object
2820 HeapRegion* hr = _g1h->heap_region_containing(obj);
2821 HeapRegionRemSet* hrrs = hr->rem_set();
2822 // Verify that the strong code root list for this region
2823 // contains the nmethod
2824 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2825 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2826 "from nmethod " PTR_FORMAT " not in strong "
2827 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2828 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2829 _failures = true;
2830 }
2831 }
2832 }
2833
2834 public:
2835 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2836 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2837
2838 void do_oop(oop* p) { do_oop_work(p); }
2839 void do_oop(narrowOop* p) { do_oop_work(p); }
2840
2841 void set_nmethod(nmethod* nm) { _nm = nm; }
2842 bool failures() { return _failures; }
2843 };
2844
2845 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2846 G1VerifyCodeRootOopClosure* _oop_cl;
2847
2848 public:
2849 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2850 _oop_cl(oop_cl) {}
2851
2852 void do_code_blob(CodeBlob* cb) {
2853 nmethod* nm = cb->as_nmethod_or_null();
2854 if (nm != NULL) {
2855 _oop_cl->set_nmethod(nm);
2856 nm->oops_do(_oop_cl);
2857 }
2858 }
2859 };
2860
2861 class YoungRefCounterClosure : public OopClosure {
2862 G1CollectedHeap* _g1h;
2863 int _count;
2864 public:
2865 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2866 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2867 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2868
2869 int count() { return _count; }
2870 void reset_count() { _count = 0; };
2871 };
2872
2873 class VerifyKlassClosure: public KlassClosure {
2874 YoungRefCounterClosure _young_ref_counter_closure;
2875 OopClosure *_oop_closure;
2876 public:
2877 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2878 void do_klass(Klass* k) {
2879 k->oops_do(_oop_closure);
2880
2881 _young_ref_counter_closure.reset_count();
2882 k->oops_do(&_young_ref_counter_closure);
2883 if (_young_ref_counter_closure.count() > 0) {
2884 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2885 }
2886 }
2887 };
2888
2889 class VerifyLivenessOopClosure: public OopClosure {
2890 G1CollectedHeap* _g1h;
2891 VerifyOption _vo;
2892 public:
2893 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2894 _g1h(g1h), _vo(vo)
2895 { }
2896 void do_oop(narrowOop *p) { do_oop_work(p); }
2897 void do_oop( oop *p) { do_oop_work(p); }
2898
2899 template <class T> void do_oop_work(T *p) {
2900 oop obj = oopDesc::load_decode_heap_oop(p);
2901 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2902 "Dead object referenced by a not dead object");
2903 }
2904 };
2905
2906 class VerifyObjsInRegionClosure: public ObjectClosure {
2907 private:
2908 G1CollectedHeap* _g1h;
2909 size_t _live_bytes;
2910 HeapRegion *_hr;
2911 VerifyOption _vo;
2912 public:
2913 // _vo == UsePrevMarking -> use "prev" marking information,
2914 // _vo == UseNextMarking -> use "next" marking information,
2915 // _vo == UseMarkWord -> use mark word from object header.
2916 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2917 : _live_bytes(0), _hr(hr), _vo(vo) {
2918 _g1h = G1CollectedHeap::heap();
2919 }
2920 void do_object(oop o) {
2921 VerifyLivenessOopClosure isLive(_g1h, _vo);
2922 assert(o != NULL, "Huh?");
2923 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2924 // If the object is alive according to the mark word,
2925 // then verify that the marking information agrees.
2926 // Note we can't verify the contra-positive of the
2927 // above: if the object is dead (according to the mark
2928 // word), it may not be marked, or may have been marked
2929 // but has since became dead, or may have been allocated
2930 // since the last marking.
2931 if (_vo == VerifyOption_G1UseMarkWord) {
2932 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2933 }
2934
2935 o->oop_iterate_no_header(&isLive);
2936 if (!_hr->obj_allocated_since_prev_marking(o)) {
2937 size_t obj_size = o->size(); // Make sure we don't overflow
2938 _live_bytes += (obj_size * HeapWordSize);
2939 }
2940 }
2941 }
2942 size_t live_bytes() { return _live_bytes; }
2943 };
2944
2945 class VerifyArchiveOopClosure: public OopClosure {
2946 public:
2947 VerifyArchiveOopClosure(HeapRegion *hr) { }
2948 void do_oop(narrowOop *p) { do_oop_work(p); }
2949 void do_oop( oop *p) { do_oop_work(p); }
2950
2951 template <class T> void do_oop_work(T *p) {
2952 oop obj = oopDesc::load_decode_heap_oop(p);
2953 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2954 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2955 p2i(p), p2i(obj));
2956 }
2957 };
2958
2959 class VerifyArchiveRegionClosure: public ObjectClosure {
2960 public:
2961 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2962 // Verify that all object pointers are to archive regions.
2963 void do_object(oop o) {
2964 VerifyArchiveOopClosure checkOop(NULL);
2965 assert(o != NULL, "Should not be here for NULL oops");
2966 o->oop_iterate_no_header(&checkOop);
2967 }
2968 };
2969
2970 class VerifyRegionClosure: public HeapRegionClosure {
2971 private:
2972 bool _par;
2973 VerifyOption _vo;
2974 bool _failures;
2975 public:
2976 // _vo == UsePrevMarking -> use "prev" marking information,
2977 // _vo == UseNextMarking -> use "next" marking information,
2978 // _vo == UseMarkWord -> use mark word from object header.
2979 VerifyRegionClosure(bool par, VerifyOption vo)
2980 : _par(par),
2981 _vo(vo),
2982 _failures(false) {}
2983
2984 bool failures() {
2985 return _failures;
2986 }
2987
2988 bool doHeapRegion(HeapRegion* r) {
2989 // For archive regions, verify there are no heap pointers to
2990 // non-pinned regions. For all others, verify liveness info.
2991 if (r->is_archive()) {
2992 VerifyArchiveRegionClosure verify_oop_pointers(r);
2993 r->object_iterate(&verify_oop_pointers);
2994 return true;
2995 }
2996 if (!r->is_continues_humongous()) {
2997 bool failures = false;
2998 r->verify(_vo, &failures);
2999 if (failures) {
3000 _failures = true;
3001 } else if (!r->is_starts_humongous()) {
3002 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3003 r->object_iterate(¬_dead_yet_cl);
3004 if (_vo != VerifyOption_G1UseNextMarking) {
3005 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3006 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3007 "max_live_bytes " SIZE_FORMAT " "
3008 "< calculated " SIZE_FORMAT,
3009 p2i(r->bottom()), p2i(r->end()),
3010 r->max_live_bytes(),
3011 not_dead_yet_cl.live_bytes());
3012 _failures = true;
3013 }
3014 } else {
3015 // When vo == UseNextMarking we cannot currently do a sanity
3016 // check on the live bytes as the calculation has not been
3017 // finalized yet.
3018 }
3019 }
3020 }
3021 return false; // stop the region iteration if we hit a failure
3022 }
3023 };
3024
3025 // This is the task used for parallel verification of the heap regions
3026
3027 class G1ParVerifyTask: public AbstractGangTask {
3028 private:
3029 G1CollectedHeap* _g1h;
3030 VerifyOption _vo;
3031 bool _failures;
3032 HeapRegionClaimer _hrclaimer;
3033
3034 public:
3035 // _vo == UsePrevMarking -> use "prev" marking information,
3036 // _vo == UseNextMarking -> use "next" marking information,
3037 // _vo == UseMarkWord -> use mark word from object header.
3038 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3039 AbstractGangTask("Parallel verify task"),
3040 _g1h(g1h),
3041 _vo(vo),
3042 _failures(false),
3043 _hrclaimer(g1h->workers()->active_workers()) {}
3044
3045 bool failures() {
3046 return _failures;
3047 }
3048
3049 void work(uint worker_id) {
3050 HandleMark hm;
3051 VerifyRegionClosure blk(true, _vo);
3052 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3053 if (blk.failures()) {
3054 _failures = true;
3055 }
3056 }
3057 };
3058
3059 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3060 if (SafepointSynchronize::is_at_safepoint()) {
3061 assert(Thread::current()->is_VM_thread(),
3062 "Expected to be executed serially by the VM thread at this point");
3063
3064 if (!silent) { gclog_or_tty->print("Roots "); }
3065 VerifyRootsClosure rootsCl(vo);
3066 VerifyKlassClosure klassCl(this, &rootsCl);
3067 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3068
3069 // We apply the relevant closures to all the oops in the
3070 // system dictionary, class loader data graph, the string table
3071 // and the nmethods in the code cache.
3072 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3073 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3074
3075 {
3076 G1RootProcessor root_processor(this, 1);
3077 root_processor.process_all_roots(&rootsCl,
3078 &cldCl,
3079 &blobsCl);
3080 }
3081
3082 bool failures = rootsCl.failures() || codeRootsCl.failures();
3083
3084 if (vo != VerifyOption_G1UseMarkWord) {
3085 // If we're verifying during a full GC then the region sets
3086 // will have been torn down at the start of the GC. Therefore
3087 // verifying the region sets will fail. So we only verify
3088 // the region sets when not in a full GC.
3089 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3090 verify_region_sets();
3091 }
3092
3093 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3094 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3095
3096 G1ParVerifyTask task(this, vo);
3097 workers()->run_task(&task);
3098 if (task.failures()) {
3099 failures = true;
3100 }
3101
3102 } else {
3103 VerifyRegionClosure blk(false, vo);
3104 heap_region_iterate(&blk);
3105 if (blk.failures()) {
3106 failures = true;
3107 }
3108 }
3109
3110 if (G1StringDedup::is_enabled()) {
3111 if (!silent) gclog_or_tty->print("StrDedup ");
3112 G1StringDedup::verify();
3113 }
3114
3115 if (failures) {
3116 gclog_or_tty->print_cr("Heap:");
3117 // It helps to have the per-region information in the output to
3118 // help us track down what went wrong. This is why we call
3119 // print_extended_on() instead of print_on().
3120 print_extended_on(gclog_or_tty);
3121 gclog_or_tty->cr();
3122 gclog_or_tty->flush();
3123 }
3124 guarantee(!failures, "there should not have been any failures");
3125 } else {
3126 if (!silent) {
3127 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3128 if (G1StringDedup::is_enabled()) {
3129 gclog_or_tty->print(", StrDedup");
3130 }
3131 gclog_or_tty->print(") ");
3132 }
3133 }
3134 }
3135
3136 void G1CollectedHeap::verify(bool silent) {
3137 verify(silent, VerifyOption_G1UsePrevMarking);
3138 }
3139
3140 double G1CollectedHeap::verify(bool guard, const char* msg) {
3141 double verify_time_ms = 0.0;
3142
3143 if (guard && total_collections() >= VerifyGCStartAt) {
3144 double verify_start = os::elapsedTime();
3145 HandleMark hm; // Discard invalid handles created during verification
3146 prepare_for_verify();
3147 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3148 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3149 }
3150
3151 return verify_time_ms;
3152 }
3153
3154 void G1CollectedHeap::verify_before_gc() {
3155 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3156 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3157 }
3158
3159 void G1CollectedHeap::verify_after_gc() {
3160 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3161 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3162 }
3163
3164 class PrintRegionClosure: public HeapRegionClosure {
3165 outputStream* _st;
3166 public:
3167 PrintRegionClosure(outputStream* st) : _st(st) {}
3168 bool doHeapRegion(HeapRegion* r) {
3169 r->print_on(_st);
3170 return false;
3171 }
3172 };
3173
3174 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3175 const HeapRegion* hr,
3176 const VerifyOption vo) const {
3177 switch (vo) {
3178 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3179 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3180 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3181 default: ShouldNotReachHere();
3182 }
3183 return false; // keep some compilers happy
3184 }
3185
3186 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3187 const VerifyOption vo) const {
3188 switch (vo) {
3189 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3190 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3191 case VerifyOption_G1UseMarkWord: {
3192 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3193 return !obj->is_gc_marked() && !hr->is_archive();
3194 }
3195 default: ShouldNotReachHere();
3196 }
3197 return false; // keep some compilers happy
3198 }
3199
3200 void G1CollectedHeap::print_on(outputStream* st) const {
3201 st->print(" %-20s", "garbage-first heap");
3202 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3203 capacity()/K, used_unlocked()/K);
3204 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3205 p2i(_hrm.reserved().start()),
3206 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3207 p2i(_hrm.reserved().end()));
3208 st->cr();
3209 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3210 uint young_regions = _young_list->length();
3211 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3212 (size_t) young_regions * HeapRegion::GrainBytes / K);
3213 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3214 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3215 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3216 st->cr();
3217 MetaspaceAux::print_on(st);
3218 }
3219
3220 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3221 print_on(st);
3222
3223 // Print the per-region information.
3224 st->cr();
3225 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3226 "HS=humongous(starts), HC=humongous(continues), "
3227 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3228 "PTAMS=previous top-at-mark-start, "
3229 "NTAMS=next top-at-mark-start)");
3230 PrintRegionClosure blk(st);
3231 heap_region_iterate(&blk);
3232 }
3233
3234 void G1CollectedHeap::print_on_error(outputStream* st) const {
3235 this->CollectedHeap::print_on_error(st);
3236
3237 if (_cm != NULL) {
3238 st->cr();
3239 _cm->print_on_error(st);
3240 }
3241 }
3242
3243 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3244 workers()->print_worker_threads_on(st);
3245 _cmThread->print_on(st);
3246 st->cr();
3247 _cm->print_worker_threads_on(st);
3248 _cg1r->print_worker_threads_on(st);
3249 if (G1StringDedup::is_enabled()) {
3250 G1StringDedup::print_worker_threads_on(st);
3251 }
3252 }
3253
3254 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3255 workers()->threads_do(tc);
3256 tc->do_thread(_cmThread);
3257 _cg1r->threads_do(tc);
3258 if (G1StringDedup::is_enabled()) {
3259 G1StringDedup::threads_do(tc);
3260 }
3261 }
3262
3263 void G1CollectedHeap::print_tracing_info() const {
3264 // We'll overload this to mean "trace GC pause statistics."
3265 if (TraceYoungGenTime || TraceOldGenTime) {
3266 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3267 // to that.
3268 g1_policy()->print_tracing_info();
3269 }
3270 if (G1SummarizeRSetStats) {
3271 g1_rem_set()->print_summary_info();
3272 }
3273 if (G1SummarizeConcMark) {
3274 concurrent_mark()->print_summary_info();
3275 }
3276 g1_policy()->print_yg_surv_rate_info();
3277 }
3278
3279 #ifndef PRODUCT
3280 // Helpful for debugging RSet issues.
3281
3282 class PrintRSetsClosure : public HeapRegionClosure {
3283 private:
3284 const char* _msg;
3285 size_t _occupied_sum;
3286
3287 public:
3288 bool doHeapRegion(HeapRegion* r) {
3289 HeapRegionRemSet* hrrs = r->rem_set();
3290 size_t occupied = hrrs->occupied();
3291 _occupied_sum += occupied;
3292
3293 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3294 HR_FORMAT_PARAMS(r));
3295 if (occupied == 0) {
3296 gclog_or_tty->print_cr(" RSet is empty");
3297 } else {
3298 hrrs->print();
3299 }
3300 gclog_or_tty->print_cr("----------");
3301 return false;
3302 }
3303
3304 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3305 gclog_or_tty->cr();
3306 gclog_or_tty->print_cr("========================================");
3307 gclog_or_tty->print_cr("%s", msg);
3308 gclog_or_tty->cr();
3309 }
3310
3311 ~PrintRSetsClosure() {
3312 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3313 gclog_or_tty->print_cr("========================================");
3314 gclog_or_tty->cr();
3315 }
3316 };
3317
3318 void G1CollectedHeap::print_cset_rsets() {
3319 PrintRSetsClosure cl("Printing CSet RSets");
3320 collection_set_iterate(&cl);
3321 }
3322
3323 void G1CollectedHeap::print_all_rsets() {
3324 PrintRSetsClosure cl("Printing All RSets");;
3325 heap_region_iterate(&cl);
3326 }
3327 #endif // PRODUCT
3328
3329 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3330 YoungList* young_list = heap()->young_list();
3331
3332 size_t eden_used_bytes = young_list->eden_used_bytes();
3333 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3334
3335 size_t eden_capacity_bytes =
3336 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3337
3338 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3339 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3340 }
3341
3342 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3343 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3344 stats->unused(), stats->used(), stats->region_end_waste(),
3345 stats->regions_filled(), stats->direct_allocated(),
3346 stats->failure_used(), stats->failure_waste());
3347 }
3348
3349 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3350 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3351 gc_tracer->report_gc_heap_summary(when, heap_summary);
3352
3353 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3354 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3355 }
3356
3357
3358 G1CollectedHeap* G1CollectedHeap::heap() {
3359 CollectedHeap* heap = Universe::heap();
3360 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3361 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3362 return (G1CollectedHeap*)heap;
3363 }
3364
3365 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3366 // always_do_update_barrier = false;
3367 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3368 // Fill TLAB's and such
3369 accumulate_statistics_all_tlabs();
3370 ensure_parsability(true);
3371
3372 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3373 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3374 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3375 }
3376 }
3377
3378 void G1CollectedHeap::gc_epilogue(bool full) {
3379
3380 if (G1SummarizeRSetStats &&
3381 (G1SummarizeRSetStatsPeriod > 0) &&
3382 // we are at the end of the GC. Total collections has already been increased.
3383 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3384 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3385 }
3386
3387 // FIXME: what is this about?
3388 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3389 // is set.
3390 #if defined(COMPILER2) || INCLUDE_JVMCI
3391 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3392 #endif
3393 // always_do_update_barrier = true;
3394
3395 resize_all_tlabs();
3396 allocation_context_stats().update(full);
3397
3398 // We have just completed a GC. Update the soft reference
3399 // policy with the new heap occupancy
3400 Universe::update_heap_info_at_gc();
3401 }
3402
3403 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3404 uint gc_count_before,
3405 bool* succeeded,
3406 GCCause::Cause gc_cause) {
3407 assert_heap_not_locked_and_not_at_safepoint();
3408 g1_policy()->record_stop_world_start();
3409 VM_G1IncCollectionPause op(gc_count_before,
3410 word_size,
3411 false, /* should_initiate_conc_mark */
3412 g1_policy()->max_pause_time_ms(),
3413 gc_cause);
3414
3415 op.set_allocation_context(AllocationContext::current());
3416 VMThread::execute(&op);
3417
3418 HeapWord* result = op.result();
3419 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3420 assert(result == NULL || ret_succeeded,
3421 "the result should be NULL if the VM did not succeed");
3422 *succeeded = ret_succeeded;
3423
3424 assert_heap_not_locked();
3425 return result;
3426 }
3427
3428 void
3429 G1CollectedHeap::doConcurrentMark() {
3430 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3431 if (!_cmThread->in_progress()) {
3432 _cmThread->set_started();
3433 CGC_lock->notify();
3434 }
3435 }
3436
3437 size_t G1CollectedHeap::pending_card_num() {
3438 size_t extra_cards = 0;
3439 JavaThread *curr = Threads::first();
3440 while (curr != NULL) {
3441 DirtyCardQueue& dcq = curr->dirty_card_queue();
3442 extra_cards += dcq.size();
3443 curr = curr->next();
3444 }
3445 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3446 size_t buffer_size = dcqs.buffer_size();
3447 size_t buffer_num = dcqs.completed_buffers_num();
3448
3449 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3450 // in bytes - not the number of 'entries'. We need to convert
3451 // into a number of cards.
3452 return (buffer_size * buffer_num + extra_cards) / oopSize;
3453 }
3454
3455 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3456 private:
3457 size_t _total_humongous;
3458 size_t _candidate_humongous;
3459
3460 DirtyCardQueue _dcq;
3461
3462 // We don't nominate objects with many remembered set entries, on
3463 // the assumption that such objects are likely still live.
3464 bool is_remset_small(HeapRegion* region) const {
3465 HeapRegionRemSet* const rset = region->rem_set();
3466 return G1EagerReclaimHumongousObjectsWithStaleRefs
3467 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3468 : rset->is_empty();
3469 }
3470
3471 bool is_typeArray_region(HeapRegion* region) const {
3472 return oop(region->bottom())->is_typeArray();
3473 }
3474
3475 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3476 assert(region->is_starts_humongous(), "Must start a humongous object");
3477
3478 // Candidate selection must satisfy the following constraints
3479 // while concurrent marking is in progress:
3480 //
3481 // * In order to maintain SATB invariants, an object must not be
3482 // reclaimed if it was allocated before the start of marking and
3483 // has not had its references scanned. Such an object must have
3484 // its references (including type metadata) scanned to ensure no
3485 // live objects are missed by the marking process. Objects
3486 // allocated after the start of concurrent marking don't need to
3487 // be scanned.
3488 //
3489 // * An object must not be reclaimed if it is on the concurrent
3490 // mark stack. Objects allocated after the start of concurrent
3491 // marking are never pushed on the mark stack.
3492 //
3493 // Nominating only objects allocated after the start of concurrent
3494 // marking is sufficient to meet both constraints. This may miss
3495 // some objects that satisfy the constraints, but the marking data
3496 // structures don't support efficiently performing the needed
3497 // additional tests or scrubbing of the mark stack.
3498 //
3499 // However, we presently only nominate is_typeArray() objects.
3500 // A humongous object containing references induces remembered
3501 // set entries on other regions. In order to reclaim such an
3502 // object, those remembered sets would need to be cleaned up.
3503 //
3504 // We also treat is_typeArray() objects specially, allowing them
3505 // to be reclaimed even if allocated before the start of
3506 // concurrent mark. For this we rely on mark stack insertion to
3507 // exclude is_typeArray() objects, preventing reclaiming an object
3508 // that is in the mark stack. We also rely on the metadata for
3509 // such objects to be built-in and so ensured to be kept live.
3510 // Frequent allocation and drop of large binary blobs is an
3511 // important use case for eager reclaim, and this special handling
3512 // may reduce needed headroom.
3513
3514 return is_typeArray_region(region) && is_remset_small(region);
3515 }
3516
3517 public:
3518 RegisterHumongousWithInCSetFastTestClosure()
3519 : _total_humongous(0),
3520 _candidate_humongous(0),
3521 _dcq(&JavaThread::dirty_card_queue_set()) {
3522 }
3523
3524 virtual bool doHeapRegion(HeapRegion* r) {
3525 if (!r->is_starts_humongous()) {
3526 return false;
3527 }
3528 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3529
3530 bool is_candidate = humongous_region_is_candidate(g1h, r);
3531 uint rindex = r->hrm_index();
3532 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3533 if (is_candidate) {
3534 _candidate_humongous++;
3535 g1h->register_humongous_region_with_cset(rindex);
3536 // Is_candidate already filters out humongous object with large remembered sets.
3537 // If we have a humongous object with a few remembered sets, we simply flush these
3538 // remembered set entries into the DCQS. That will result in automatic
3539 // re-evaluation of their remembered set entries during the following evacuation
3540 // phase.
3541 if (!r->rem_set()->is_empty()) {
3542 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3543 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3544 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3545 HeapRegionRemSetIterator hrrs(r->rem_set());
3546 size_t card_index;
3547 while (hrrs.has_next(card_index)) {
3548 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3549 // The remembered set might contain references to already freed
3550 // regions. Filter out such entries to avoid failing card table
3551 // verification.
3552 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3553 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3554 *card_ptr = CardTableModRefBS::dirty_card_val();
3555 _dcq.enqueue(card_ptr);
3556 }
3557 }
3558 }
3559 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3560 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3561 hrrs.n_yielded(), r->rem_set()->occupied());
3562 r->rem_set()->clear_locked();
3563 }
3564 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3565 }
3566 _total_humongous++;
3567
3568 return false;
3569 }
3570
3571 size_t total_humongous() const { return _total_humongous; }
3572 size_t candidate_humongous() const { return _candidate_humongous; }
3573
3574 void flush_rem_set_entries() { _dcq.flush(); }
3575 };
3576
3577 void G1CollectedHeap::register_humongous_regions_with_cset() {
3578 if (!G1EagerReclaimHumongousObjects) {
3579 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3580 return;
3581 }
3582 double time = os::elapsed_counter();
3583
3584 // Collect reclaim candidate information and register candidates with cset.
3585 RegisterHumongousWithInCSetFastTestClosure cl;
3586 heap_region_iterate(&cl);
3587
3588 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3589 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3590 cl.total_humongous(),
3591 cl.candidate_humongous());
3592 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3593
3594 // Finally flush all remembered set entries to re-check into the global DCQS.
3595 cl.flush_rem_set_entries();
3596 }
3597
3598 #ifdef ASSERT
3599 class VerifyCSetClosure: public HeapRegionClosure {
3600 public:
3601 bool doHeapRegion(HeapRegion* hr) {
3602 // Here we check that the CSet region's RSet is ready for parallel
3603 // iteration. The fields that we'll verify are only manipulated
3604 // when the region is part of a CSet and is collected. Afterwards,
3605 // we reset these fields when we clear the region's RSet (when the
3606 // region is freed) so they are ready when the region is
3607 // re-allocated. The only exception to this is if there's an
3608 // evacuation failure and instead of freeing the region we leave
3609 // it in the heap. In that case, we reset these fields during
3610 // evacuation failure handling.
3611 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3612
3613 // Here's a good place to add any other checks we'd like to
3614 // perform on CSet regions.
3615 return false;
3616 }
3617 };
3618 #endif // ASSERT
3619
3620 uint G1CollectedHeap::num_task_queues() const {
3621 return _task_queues->size();
3622 }
3623
3624 #if TASKQUEUE_STATS
3625 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3626 st->print_raw_cr("GC Task Stats");
3627 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3628 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3629 }
3630
3631 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3632 print_taskqueue_stats_hdr(st);
3633
3634 TaskQueueStats totals;
3635 const uint n = num_task_queues();
3636 for (uint i = 0; i < n; ++i) {
3637 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3638 totals += task_queue(i)->stats;
3639 }
3640 st->print_raw("tot "); totals.print(st); st->cr();
3641
3642 DEBUG_ONLY(totals.verify());
3643 }
3644
3645 void G1CollectedHeap::reset_taskqueue_stats() {
3646 const uint n = num_task_queues();
3647 for (uint i = 0; i < n; ++i) {
3648 task_queue(i)->stats.reset();
3649 }
3650 }
3651 #endif // TASKQUEUE_STATS
3652
3653 void G1CollectedHeap::log_gc_header() {
3654 if (!G1Log::fine()) {
3655 return;
3656 }
3657
3658 gclog_or_tty->gclog_stamp();
3659
3660 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3661 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3662 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3663
3664 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3665 }
3666
3667 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3668 if (!G1Log::fine()) {
3669 return;
3670 }
3671
3672 if (G1Log::finer()) {
3673 if (evacuation_failed()) {
3674 gclog_or_tty->print(" (to-space exhausted)");
3675 }
3676 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3677 g1_policy()->print_phases(pause_time_sec);
3678 g1_policy()->print_detailed_heap_transition();
3679 } else {
3680 if (evacuation_failed()) {
3681 gclog_or_tty->print("--");
3682 }
3683 g1_policy()->print_heap_transition();
3684 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3685 }
3686 gclog_or_tty->flush();
3687 }
3688
3689 void G1CollectedHeap::wait_for_root_region_scanning() {
3690 double scan_wait_start = os::elapsedTime();
3691 // We have to wait until the CM threads finish scanning the
3692 // root regions as it's the only way to ensure that all the
3693 // objects on them have been correctly scanned before we start
3694 // moving them during the GC.
3695 bool waited = _cm->root_regions()->wait_until_scan_finished();
3696 double wait_time_ms = 0.0;
3697 if (waited) {
3698 double scan_wait_end = os::elapsedTime();
3699 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3700 }
3701 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3702 }
3703
3704 bool
3705 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3706 assert_at_safepoint(true /* should_be_vm_thread */);
3707 guarantee(!is_gc_active(), "collection is not reentrant");
3708
3709 if (GC_locker::check_active_before_gc()) {
3710 return false;
3711 }
3712
3713 _gc_timer_stw->register_gc_start();
3714
3715 GCIdMark gc_id_mark;
3716 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3717
3718 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3719 ResourceMark rm;
3720
3721 wait_for_root_region_scanning();
3722
3723 G1Log::update_level();
3724 print_heap_before_gc();
3725 trace_heap_before_gc(_gc_tracer_stw);
3726
3727 verify_region_sets_optional();
3728 verify_dirty_young_regions();
3729
3730 // This call will decide whether this pause is an initial-mark
3731 // pause. If it is, during_initial_mark_pause() will return true
3732 // for the duration of this pause.
3733 g1_policy()->decide_on_conc_mark_initiation();
3734
3735 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3736 assert(!collector_state()->during_initial_mark_pause() ||
3737 collector_state()->gcs_are_young(), "sanity");
3738
3739 // We also do not allow mixed GCs during marking.
3740 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3741
3742 // Record whether this pause is an initial mark. When the current
3743 // thread has completed its logging output and it's safe to signal
3744 // the CM thread, the flag's value in the policy has been reset.
3745 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3746
3747 // Inner scope for scope based logging, timers, and stats collection
3748 {
3749 EvacuationInfo evacuation_info;
3750
3751 if (collector_state()->during_initial_mark_pause()) {
3752 // We are about to start a marking cycle, so we increment the
3753 // full collection counter.
3754 increment_old_marking_cycles_started();
3755 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3756 }
3757
3758 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3759
3760 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3761
3762 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3763 workers()->active_workers(),
3764 Threads::number_of_non_daemon_threads());
3765 workers()->set_active_workers(active_workers);
3766
3767 double pause_start_sec = os::elapsedTime();
3768 g1_policy()->note_gc_start(active_workers);
3769 log_gc_header();
3770
3771 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3772 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3773
3774 // If the secondary_free_list is not empty, append it to the
3775 // free_list. No need to wait for the cleanup operation to finish;
3776 // the region allocation code will check the secondary_free_list
3777 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3778 // set, skip this step so that the region allocation code has to
3779 // get entries from the secondary_free_list.
3780 if (!G1StressConcRegionFreeing) {
3781 append_secondary_free_list_if_not_empty_with_lock();
3782 }
3783
3784 assert(check_young_list_well_formed(), "young list should be well formed");
3785
3786 // Don't dynamically change the number of GC threads this early. A value of
3787 // 0 is used to indicate serial work. When parallel work is done,
3788 // it will be set.
3789
3790 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3791 IsGCActiveMark x;
3792
3793 gc_prologue(false);
3794 increment_total_collections(false /* full gc */);
3795 increment_gc_time_stamp();
3796
3797 verify_before_gc();
3798
3799 check_bitmaps("GC Start");
3800
3801 #if defined(COMPILER2) || INCLUDE_JVMCI
3802 DerivedPointerTable::clear();
3803 #endif
3804
3805 // Please see comment in g1CollectedHeap.hpp and
3806 // G1CollectedHeap::ref_processing_init() to see how
3807 // reference processing currently works in G1.
3808
3809 // Enable discovery in the STW reference processor
3810 ref_processor_stw()->enable_discovery();
3811
3812 {
3813 // We want to temporarily turn off discovery by the
3814 // CM ref processor, if necessary, and turn it back on
3815 // on again later if we do. Using a scoped
3816 // NoRefDiscovery object will do this.
3817 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3818
3819 // Forget the current alloc region (we might even choose it to be part
3820 // of the collection set!).
3821 _allocator->release_mutator_alloc_region();
3822
3823 // We should call this after we retire the mutator alloc
3824 // region(s) so that all the ALLOC / RETIRE events are generated
3825 // before the start GC event.
3826 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3827
3828 // This timing is only used by the ergonomics to handle our pause target.
3829 // It is unclear why this should not include the full pause. We will
3830 // investigate this in CR 7178365.
3831 //
3832 // Preserving the old comment here if that helps the investigation:
3833 //
3834 // The elapsed time induced by the start time below deliberately elides
3835 // the possible verification above.
3836 double sample_start_time_sec = os::elapsedTime();
3837
3838 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3839
3840 if (collector_state()->during_initial_mark_pause()) {
3841 concurrent_mark()->checkpointRootsInitialPre();
3842 }
3843
3844 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3845 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3846
3847 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3848
3849 // Make sure the remembered sets are up to date. This needs to be
3850 // done before register_humongous_regions_with_cset(), because the
3851 // remembered sets are used there to choose eager reclaim candidates.
3852 // If the remembered sets are not up to date we might miss some
3853 // entries that need to be handled.
3854 g1_rem_set()->cleanupHRRS();
3855
3856 register_humongous_regions_with_cset();
3857
3858 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3859
3860 _cm->note_start_of_gc();
3861 // We call this after finalize_cset() to
3862 // ensure that the CSet has been finalized.
3863 _cm->verify_no_cset_oops();
3864
3865 if (_hr_printer.is_active()) {
3866 HeapRegion* hr = g1_policy()->collection_set();
3867 while (hr != NULL) {
3868 _hr_printer.cset(hr);
3869 hr = hr->next_in_collection_set();
3870 }
3871 }
3872
3873 #ifdef ASSERT
3874 VerifyCSetClosure cl;
3875 collection_set_iterate(&cl);
3876 #endif // ASSERT
3877
3878 // Initialize the GC alloc regions.
3879 _allocator->init_gc_alloc_regions(evacuation_info);
3880
3881 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3882 pre_evacuate_collection_set();
3883
3884 // Actually do the work...
3885 evacuate_collection_set(evacuation_info, &per_thread_states);
3886
3887 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3888
3889 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3890 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3891
3892 eagerly_reclaim_humongous_regions();
3893
3894 g1_policy()->clear_collection_set();
3895
3896 // Start a new incremental collection set for the next pause.
3897 g1_policy()->start_incremental_cset_building();
3898
3899 clear_cset_fast_test();
3900
3901 _young_list->reset_sampled_info();
3902
3903 // Don't check the whole heap at this point as the
3904 // GC alloc regions from this pause have been tagged
3905 // as survivors and moved on to the survivor list.
3906 // Survivor regions will fail the !is_young() check.
3907 assert(check_young_list_empty(false /* check_heap */),
3908 "young list should be empty");
3909
3910 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3911 _young_list->first_survivor_region(),
3912 _young_list->last_survivor_region());
3913
3914 _young_list->reset_auxilary_lists();
3915
3916 if (evacuation_failed()) {
3917 set_used(recalculate_used());
3918 if (_archive_allocator != NULL) {
3919 _archive_allocator->clear_used();
3920 }
3921 for (uint i = 0; i < ParallelGCThreads; i++) {
3922 if (_evacuation_failed_info_array[i].has_failed()) {
3923 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3924 }
3925 }
3926 } else {
3927 // The "used" of the the collection set have already been subtracted
3928 // when they were freed. Add in the bytes evacuated.
3929 increase_used(g1_policy()->bytes_copied_during_gc());
3930 }
3931
3932 if (collector_state()->during_initial_mark_pause()) {
3933 // We have to do this before we notify the CM threads that
3934 // they can start working to make sure that all the
3935 // appropriate initialization is done on the CM object.
3936 concurrent_mark()->checkpointRootsInitialPost();
3937 collector_state()->set_mark_in_progress(true);
3938 // Note that we don't actually trigger the CM thread at
3939 // this point. We do that later when we're sure that
3940 // the current thread has completed its logging output.
3941 }
3942
3943 allocate_dummy_regions();
3944
3945 _allocator->init_mutator_alloc_region();
3946
3947 {
3948 size_t expand_bytes = g1_policy()->expansion_amount();
3949 if (expand_bytes > 0) {
3950 size_t bytes_before = capacity();
3951 // No need for an ergo verbose message here,
3952 // expansion_amount() does this when it returns a value > 0.
3953 double expand_ms;
3954 if (!expand(expand_bytes, &expand_ms)) {
3955 // We failed to expand the heap. Cannot do anything about it.
3956 }
3957 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3958 }
3959 }
3960
3961 // We redo the verification but now wrt to the new CSet which
3962 // has just got initialized after the previous CSet was freed.
3963 _cm->verify_no_cset_oops();
3964 _cm->note_end_of_gc();
3965
3966 // This timing is only used by the ergonomics to handle our pause target.
3967 // It is unclear why this should not include the full pause. We will
3968 // investigate this in CR 7178365.
3969 double sample_end_time_sec = os::elapsedTime();
3970 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3971 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3972 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3973
3974 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3975 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3976
3977 MemoryService::track_memory_usage();
3978
3979 // In prepare_for_verify() below we'll need to scan the deferred
3980 // update buffers to bring the RSets up-to-date if
3981 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3982 // the update buffers we'll probably need to scan cards on the
3983 // regions we just allocated to (i.e., the GC alloc
3984 // regions). However, during the last GC we called
3985 // set_saved_mark() on all the GC alloc regions, so card
3986 // scanning might skip the [saved_mark_word()...top()] area of
3987 // those regions (i.e., the area we allocated objects into
3988 // during the last GC). But it shouldn't. Given that
3989 // saved_mark_word() is conditional on whether the GC time stamp
3990 // on the region is current or not, by incrementing the GC time
3991 // stamp here we invalidate all the GC time stamps on all the
3992 // regions and saved_mark_word() will simply return top() for
3993 // all the regions. This is a nicer way of ensuring this rather
3994 // than iterating over the regions and fixing them. In fact, the
3995 // GC time stamp increment here also ensures that
3996 // saved_mark_word() will return top() between pauses, i.e.,
3997 // during concurrent refinement. So we don't need the
3998 // is_gc_active() check to decided which top to use when
3999 // scanning cards (see CR 7039627).
4000 increment_gc_time_stamp();
4001
4002 verify_after_gc();
4003 check_bitmaps("GC End");
4004
4005 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4006 ref_processor_stw()->verify_no_references_recorded();
4007
4008 // CM reference discovery will be re-enabled if necessary.
4009 }
4010
4011 // We should do this after we potentially expand the heap so
4012 // that all the COMMIT events are generated before the end GC
4013 // event, and after we retire the GC alloc regions so that all
4014 // RETIRE events are generated before the end GC event.
4015 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4016
4017 #ifdef TRACESPINNING
4018 ParallelTaskTerminator::print_termination_counts();
4019 #endif
4020
4021 gc_epilogue(false);
4022 }
4023
4024 // Print the remainder of the GC log output.
4025 log_gc_footer(os::elapsedTime() - pause_start_sec);
4026
4027 // It is not yet to safe to tell the concurrent mark to
4028 // start as we have some optional output below. We don't want the
4029 // output from the concurrent mark thread interfering with this
4030 // logging output either.
4031
4032 _hrm.verify_optional();
4033 verify_region_sets_optional();
4034
4035 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4036 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4037
4038 print_heap_after_gc();
4039 trace_heap_after_gc(_gc_tracer_stw);
4040
4041 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4042 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4043 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4044 // before any GC notifications are raised.
4045 g1mm()->update_sizes();
4046
4047 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4048 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4049 _gc_timer_stw->register_gc_end();
4050 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4051 }
4052 // It should now be safe to tell the concurrent mark thread to start
4053 // without its logging output interfering with the logging output
4054 // that came from the pause.
4055
4056 if (should_start_conc_mark) {
4057 // CAUTION: after the doConcurrentMark() call below,
4058 // the concurrent marking thread(s) could be running
4059 // concurrently with us. Make sure that anything after
4060 // this point does not assume that we are the only GC thread
4061 // running. Note: of course, the actual marking work will
4062 // not start until the safepoint itself is released in
4063 // SuspendibleThreadSet::desynchronize().
4064 doConcurrentMark();
4065 }
4066
4067 return true;
4068 }
4069
4070 void G1CollectedHeap::remove_self_forwarding_pointers() {
4071 double remove_self_forwards_start = os::elapsedTime();
4072
4073 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4074 workers()->run_task(&rsfp_task);
4075
4076 // Now restore saved marks, if any.
4077 for (uint i = 0; i < ParallelGCThreads; i++) {
4078 OopAndMarkOopStack& cur = _preserved_objs[i];
4079 while (!cur.is_empty()) {
4080 OopAndMarkOop elem = cur.pop();
4081 elem.set_mark();
4082 }
4083 cur.clear(true);
4084 }
4085
4086 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4087 }
4088
4089 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4090 if (!_evacuation_failed) {
4091 _evacuation_failed = true;
4092 }
4093
4094 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4095
4096 // We want to call the "for_promotion_failure" version only in the
4097 // case of a promotion failure.
4098 if (m->must_be_preserved_for_promotion_failure(obj)) {
4099 OopAndMarkOop elem(obj, m);
4100 _preserved_objs[worker_id].push(elem);
4101 }
4102 }
4103
4104 class G1ParEvacuateFollowersClosure : public VoidClosure {
4105 private:
4106 double _start_term;
4107 double _term_time;
4108 size_t _term_attempts;
4109
4110 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4111 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4112 protected:
4113 G1CollectedHeap* _g1h;
4114 G1ParScanThreadState* _par_scan_state;
4115 RefToScanQueueSet* _queues;
4116 ParallelTaskTerminator* _terminator;
4117
4118 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4119 RefToScanQueueSet* queues() { return _queues; }
4120 ParallelTaskTerminator* terminator() { return _terminator; }
4121
4122 public:
4123 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4124 G1ParScanThreadState* par_scan_state,
4125 RefToScanQueueSet* queues,
4126 ParallelTaskTerminator* terminator)
4127 : _g1h(g1h), _par_scan_state(par_scan_state),
4128 _queues(queues), _terminator(terminator),
4129 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4130
4131 void do_void();
4132
4133 double term_time() const { return _term_time; }
4134 size_t term_attempts() const { return _term_attempts; }
4135
4136 private:
4137 inline bool offer_termination();
4138 };
4139
4140 bool G1ParEvacuateFollowersClosure::offer_termination() {
4141 G1ParScanThreadState* const pss = par_scan_state();
4142 start_term_time();
4143 const bool res = terminator()->offer_termination();
4144 end_term_time();
4145 return res;
4146 }
4147
4148 void G1ParEvacuateFollowersClosure::do_void() {
4149 G1ParScanThreadState* const pss = par_scan_state();
4150 pss->trim_queue();
4151 do {
4152 pss->steal_and_trim_queue(queues());
4153 } while (!offer_termination());
4154 }
4155
4156 class G1ParTask : public AbstractGangTask {
4157 protected:
4158 G1CollectedHeap* _g1h;
4159 G1ParScanThreadStateSet* _pss;
4160 RefToScanQueueSet* _queues;
4161 G1RootProcessor* _root_processor;
4162 ParallelTaskTerminator _terminator;
4163 uint _n_workers;
4164
4165 public:
4166 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4167 : AbstractGangTask("G1 collection"),
4168 _g1h(g1h),
4169 _pss(per_thread_states),
4170 _queues(task_queues),
4171 _root_processor(root_processor),
4172 _terminator(n_workers, _queues),
4173 _n_workers(n_workers)
4174 {}
4175
4176 void work(uint worker_id) {
4177 if (worker_id >= _n_workers) return; // no work needed this round
4178
4179 double start_sec = os::elapsedTime();
4180 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4181
4182 {
4183 ResourceMark rm;
4184 HandleMark hm;
4185
4186 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4187
4188 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4189 pss->set_ref_processor(rp);
4190
4191 double start_strong_roots_sec = os::elapsedTime();
4192
4193 _root_processor->evacuate_roots(pss->closures(), worker_id);
4194
4195 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4196
4197 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4198 // treating the nmethods visited to act as roots for concurrent marking.
4199 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4200 // objects copied by the current evacuation.
4201 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4202 pss->closures()->weak_codeblobs(),
4203 worker_id);
4204
4205 _pss->add_cards_scanned(worker_id, cards_scanned);
4206
4207 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4208
4209 double term_sec = 0.0;
4210 size_t evac_term_attempts = 0;
4211 {
4212 double start = os::elapsedTime();
4213 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4214 evac.do_void();
4215
4216 evac_term_attempts = evac.term_attempts();
4217 term_sec = evac.term_time();
4218 double elapsed_sec = os::elapsedTime() - start;
4219 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4220 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4221 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4222 }
4223
4224 assert(pss->queue_is_empty(), "should be empty");
4225
4226 if (PrintTerminationStats) {
4227 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4228 size_t lab_waste;
4229 size_t lab_undo_waste;
4230 pss->waste(lab_waste, lab_undo_waste);
4231 _g1h->print_termination_stats(gclog_or_tty,
4232 worker_id,
4233 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4234 strong_roots_sec * 1000.0, /* strong roots time */
4235 term_sec * 1000.0, /* evac term time */
4236 evac_term_attempts, /* evac term attempts */
4237 lab_waste, /* alloc buffer waste */
4238 lab_undo_waste /* undo waste */
4239 );
4240 }
4241
4242 // Close the inner scope so that the ResourceMark and HandleMark
4243 // destructors are executed here and are included as part of the
4244 // "GC Worker Time".
4245 }
4246 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4247 }
4248 };
4249
4250 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4251 st->print_raw_cr("GC Termination Stats");
4252 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4253 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4254 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4255 }
4256
4257 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4258 uint worker_id,
4259 double elapsed_ms,
4260 double strong_roots_ms,
4261 double term_ms,
4262 size_t term_attempts,
4263 size_t alloc_buffer_waste,
4264 size_t undo_waste) const {
4265 st->print_cr("%3d %9.2f %9.2f %6.2f "
4266 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4267 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4268 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4269 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4270 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4271 alloc_buffer_waste * HeapWordSize / K,
4272 undo_waste * HeapWordSize / K);
4273 }
4274
4275 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4276 private:
4277 BoolObjectClosure* _is_alive;
4278 int _initial_string_table_size;
4279 int _initial_symbol_table_size;
4280
4281 bool _process_strings;
4282 int _strings_processed;
4283 int _strings_removed;
4284
4285 bool _process_symbols;
4286 int _symbols_processed;
4287 int _symbols_removed;
4288
4289 public:
4290 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4291 AbstractGangTask("String/Symbol Unlinking"),
4292 _is_alive(is_alive),
4293 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4294 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4295
4296 _initial_string_table_size = StringTable::the_table()->table_size();
4297 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4298 if (process_strings) {
4299 StringTable::clear_parallel_claimed_index();
4300 }
4301 if (process_symbols) {
4302 SymbolTable::clear_parallel_claimed_index();
4303 }
4304 }
4305
4306 ~G1StringSymbolTableUnlinkTask() {
4307 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4308 "claim value %d after unlink less than initial string table size %d",
4309 StringTable::parallel_claimed_index(), _initial_string_table_size);
4310 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4311 "claim value %d after unlink less than initial symbol table size %d",
4312 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4313
4314 if (G1TraceStringSymbolTableScrubbing) {
4315 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4316 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4317 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4318 strings_processed(), strings_removed(),
4319 symbols_processed(), symbols_removed());
4320 }
4321 }
4322
4323 void work(uint worker_id) {
4324 int strings_processed = 0;
4325 int strings_removed = 0;
4326 int symbols_processed = 0;
4327 int symbols_removed = 0;
4328 if (_process_strings) {
4329 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4330 Atomic::add(strings_processed, &_strings_processed);
4331 Atomic::add(strings_removed, &_strings_removed);
4332 }
4333 if (_process_symbols) {
4334 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4335 Atomic::add(symbols_processed, &_symbols_processed);
4336 Atomic::add(symbols_removed, &_symbols_removed);
4337 }
4338 }
4339
4340 size_t strings_processed() const { return (size_t)_strings_processed; }
4341 size_t strings_removed() const { return (size_t)_strings_removed; }
4342
4343 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4344 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4345 };
4346
4347 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4348 private:
4349 static Monitor* _lock;
4350
4351 BoolObjectClosure* const _is_alive;
4352 const bool _unloading_occurred;
4353 const uint _num_workers;
4354
4355 // Variables used to claim nmethods.
4356 nmethod* _first_nmethod;
4357 volatile nmethod* _claimed_nmethod;
4358
4359 // The list of nmethods that need to be processed by the second pass.
4360 volatile nmethod* _postponed_list;
4361 volatile uint _num_entered_barrier;
4362
4363 public:
4364 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4365 _is_alive(is_alive),
4366 _unloading_occurred(unloading_occurred),
4367 _num_workers(num_workers),
4368 _first_nmethod(NULL),
4369 _claimed_nmethod(NULL),
4370 _postponed_list(NULL),
4371 _num_entered_barrier(0)
4372 {
4373 nmethod::increase_unloading_clock();
4374 // Get first alive nmethod
4375 NMethodIterator iter = NMethodIterator();
4376 if(iter.next_alive()) {
4377 _first_nmethod = iter.method();
4378 }
4379 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4380 }
4381
4382 ~G1CodeCacheUnloadingTask() {
4383 CodeCache::verify_clean_inline_caches();
4384
4385 CodeCache::set_needs_cache_clean(false);
4386 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4387
4388 CodeCache::verify_icholder_relocations();
4389 }
4390
4391 private:
4392 void add_to_postponed_list(nmethod* nm) {
4393 nmethod* old;
4394 do {
4395 old = (nmethod*)_postponed_list;
4396 nm->set_unloading_next(old);
4397 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4398 }
4399
4400 void clean_nmethod(nmethod* nm) {
4401 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4402
4403 if (postponed) {
4404 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4405 add_to_postponed_list(nm);
4406 }
4407
4408 // Mark that this thread has been cleaned/unloaded.
4409 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4410 nm->set_unloading_clock(nmethod::global_unloading_clock());
4411 }
4412
4413 void clean_nmethod_postponed(nmethod* nm) {
4414 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4415 }
4416
4417 static const int MaxClaimNmethods = 16;
4418
4419 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4420 nmethod* first;
4421 NMethodIterator last;
4422
4423 do {
4424 *num_claimed_nmethods = 0;
4425
4426 first = (nmethod*)_claimed_nmethod;
4427 last = NMethodIterator(first);
4428
4429 if (first != NULL) {
4430
4431 for (int i = 0; i < MaxClaimNmethods; i++) {
4432 if (!last.next_alive()) {
4433 break;
4434 }
4435 claimed_nmethods[i] = last.method();
4436 (*num_claimed_nmethods)++;
4437 }
4438 }
4439
4440 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4441 }
4442
4443 nmethod* claim_postponed_nmethod() {
4444 nmethod* claim;
4445 nmethod* next;
4446
4447 do {
4448 claim = (nmethod*)_postponed_list;
4449 if (claim == NULL) {
4450 return NULL;
4451 }
4452
4453 next = claim->unloading_next();
4454
4455 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4456
4457 return claim;
4458 }
4459
4460 public:
4461 // Mark that we're done with the first pass of nmethod cleaning.
4462 void barrier_mark(uint worker_id) {
4463 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4464 _num_entered_barrier++;
4465 if (_num_entered_barrier == _num_workers) {
4466 ml.notify_all();
4467 }
4468 }
4469
4470 // See if we have to wait for the other workers to
4471 // finish their first-pass nmethod cleaning work.
4472 void barrier_wait(uint worker_id) {
4473 if (_num_entered_barrier < _num_workers) {
4474 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4475 while (_num_entered_barrier < _num_workers) {
4476 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4477 }
4478 }
4479 }
4480
4481 // Cleaning and unloading of nmethods. Some work has to be postponed
4482 // to the second pass, when we know which nmethods survive.
4483 void work_first_pass(uint worker_id) {
4484 // The first nmethods is claimed by the first worker.
4485 if (worker_id == 0 && _first_nmethod != NULL) {
4486 clean_nmethod(_first_nmethod);
4487 _first_nmethod = NULL;
4488 }
4489
4490 int num_claimed_nmethods;
4491 nmethod* claimed_nmethods[MaxClaimNmethods];
4492
4493 while (true) {
4494 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4495
4496 if (num_claimed_nmethods == 0) {
4497 break;
4498 }
4499
4500 for (int i = 0; i < num_claimed_nmethods; i++) {
4501 clean_nmethod(claimed_nmethods[i]);
4502 }
4503 }
4504 }
4505
4506 void work_second_pass(uint worker_id) {
4507 nmethod* nm;
4508 // Take care of postponed nmethods.
4509 while ((nm = claim_postponed_nmethod()) != NULL) {
4510 clean_nmethod_postponed(nm);
4511 }
4512 }
4513 };
4514
4515 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4516
4517 class G1KlassCleaningTask : public StackObj {
4518 BoolObjectClosure* _is_alive;
4519 volatile jint _clean_klass_tree_claimed;
4520 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4521
4522 public:
4523 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4524 _is_alive(is_alive),
4525 _clean_klass_tree_claimed(0),
4526 _klass_iterator() {
4527 }
4528
4529 private:
4530 bool claim_clean_klass_tree_task() {
4531 if (_clean_klass_tree_claimed) {
4532 return false;
4533 }
4534
4535 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4536 }
4537
4538 InstanceKlass* claim_next_klass() {
4539 Klass* klass;
4540 do {
4541 klass =_klass_iterator.next_klass();
4542 } while (klass != NULL && !klass->is_instance_klass());
4543
4544 // this can be null so don't call InstanceKlass::cast
4545 return static_cast<InstanceKlass*>(klass);
4546 }
4547
4548 public:
4549
4550 void clean_klass(InstanceKlass* ik) {
4551 ik->clean_weak_instanceklass_links(_is_alive);
4552 }
4553
4554 void work() {
4555 ResourceMark rm;
4556
4557 // One worker will clean the subklass/sibling klass tree.
4558 if (claim_clean_klass_tree_task()) {
4559 Klass::clean_subklass_tree(_is_alive);
4560 }
4561
4562 // All workers will help cleaning the classes,
4563 InstanceKlass* klass;
4564 while ((klass = claim_next_klass()) != NULL) {
4565 clean_klass(klass);
4566 }
4567 }
4568 };
4569
4570 // To minimize the remark pause times, the tasks below are done in parallel.
4571 class G1ParallelCleaningTask : public AbstractGangTask {
4572 private:
4573 G1StringSymbolTableUnlinkTask _string_symbol_task;
4574 G1CodeCacheUnloadingTask _code_cache_task;
4575 G1KlassCleaningTask _klass_cleaning_task;
4576
4577 public:
4578 // The constructor is run in the VMThread.
4579 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4580 AbstractGangTask("Parallel Cleaning"),
4581 _string_symbol_task(is_alive, process_strings, process_symbols),
4582 _code_cache_task(num_workers, is_alive, unloading_occurred),
4583 _klass_cleaning_task(is_alive) {
4584 }
4585
4586 // The parallel work done by all worker threads.
4587 void work(uint worker_id) {
4588 // Do first pass of code cache cleaning.
4589 _code_cache_task.work_first_pass(worker_id);
4590
4591 // Let the threads mark that the first pass is done.
4592 _code_cache_task.barrier_mark(worker_id);
4593
4594 // Clean the Strings and Symbols.
4595 _string_symbol_task.work(worker_id);
4596
4597 // Wait for all workers to finish the first code cache cleaning pass.
4598 _code_cache_task.barrier_wait(worker_id);
4599
4600 // Do the second code cache cleaning work, which realize on
4601 // the liveness information gathered during the first pass.
4602 _code_cache_task.work_second_pass(worker_id);
4603
4604 // Clean all klasses that were not unloaded.
4605 _klass_cleaning_task.work();
4606 }
4607 };
4608
4609
4610 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4611 bool process_strings,
4612 bool process_symbols,
4613 bool class_unloading_occurred) {
4614 uint n_workers = workers()->active_workers();
4615
4616 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4617 n_workers, class_unloading_occurred);
4618 workers()->run_task(&g1_unlink_task);
4619 }
4620
4621 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4622 bool process_strings, bool process_symbols) {
4623 {
4624 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4625 workers()->run_task(&g1_unlink_task);
4626 }
4627
4628 if (G1StringDedup::is_enabled()) {
4629 G1StringDedup::unlink(is_alive);
4630 }
4631 }
4632
4633 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4634 private:
4635 DirtyCardQueueSet* _queue;
4636 public:
4637 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4638
4639 virtual void work(uint worker_id) {
4640 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4641 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4642
4643 RedirtyLoggedCardTableEntryClosure cl;
4644 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4645
4646 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4647 }
4648 };
4649
4650 void G1CollectedHeap::redirty_logged_cards() {
4651 double redirty_logged_cards_start = os::elapsedTime();
4652
4653 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4654 dirty_card_queue_set().reset_for_par_iteration();
4655 workers()->run_task(&redirty_task);
4656
4657 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4658 dcq.merge_bufferlists(&dirty_card_queue_set());
4659 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4660
4661 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4662 }
4663
4664 // Weak Reference Processing support
4665
4666 // An always "is_alive" closure that is used to preserve referents.
4667 // If the object is non-null then it's alive. Used in the preservation
4668 // of referent objects that are pointed to by reference objects
4669 // discovered by the CM ref processor.
4670 class G1AlwaysAliveClosure: public BoolObjectClosure {
4671 G1CollectedHeap* _g1;
4672 public:
4673 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4674 bool do_object_b(oop p) {
4675 if (p != NULL) {
4676 return true;
4677 }
4678 return false;
4679 }
4680 };
4681
4682 bool G1STWIsAliveClosure::do_object_b(oop p) {
4683 // An object is reachable if it is outside the collection set,
4684 // or is inside and copied.
4685 return !_g1->is_in_cset(p) || p->is_forwarded();
4686 }
4687
4688 // Non Copying Keep Alive closure
4689 class G1KeepAliveClosure: public OopClosure {
4690 G1CollectedHeap* _g1;
4691 public:
4692 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4693 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4694 void do_oop(oop* p) {
4695 oop obj = *p;
4696 assert(obj != NULL, "the caller should have filtered out NULL values");
4697
4698 const InCSetState cset_state = _g1->in_cset_state(obj);
4699 if (!cset_state.is_in_cset_or_humongous()) {
4700 return;
4701 }
4702 if (cset_state.is_in_cset()) {
4703 assert( obj->is_forwarded(), "invariant" );
4704 *p = obj->forwardee();
4705 } else {
4706 assert(!obj->is_forwarded(), "invariant" );
4707 assert(cset_state.is_humongous(),
4708 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4709 _g1->set_humongous_is_live(obj);
4710 }
4711 }
4712 };
4713
4714 // Copying Keep Alive closure - can be called from both
4715 // serial and parallel code as long as different worker
4716 // threads utilize different G1ParScanThreadState instances
4717 // and different queues.
4718
4719 class G1CopyingKeepAliveClosure: public OopClosure {
4720 G1CollectedHeap* _g1h;
4721 OopClosure* _copy_non_heap_obj_cl;
4722 G1ParScanThreadState* _par_scan_state;
4723
4724 public:
4725 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4726 OopClosure* non_heap_obj_cl,
4727 G1ParScanThreadState* pss):
4728 _g1h(g1h),
4729 _copy_non_heap_obj_cl(non_heap_obj_cl),
4730 _par_scan_state(pss)
4731 {}
4732
4733 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4734 virtual void do_oop( oop* p) { do_oop_work(p); }
4735
4736 template <class T> void do_oop_work(T* p) {
4737 oop obj = oopDesc::load_decode_heap_oop(p);
4738
4739 if (_g1h->is_in_cset_or_humongous(obj)) {
4740 // If the referent object has been forwarded (either copied
4741 // to a new location or to itself in the event of an
4742 // evacuation failure) then we need to update the reference
4743 // field and, if both reference and referent are in the G1
4744 // heap, update the RSet for the referent.
4745 //
4746 // If the referent has not been forwarded then we have to keep
4747 // it alive by policy. Therefore we have copy the referent.
4748 //
4749 // If the reference field is in the G1 heap then we can push
4750 // on the PSS queue. When the queue is drained (after each
4751 // phase of reference processing) the object and it's followers
4752 // will be copied, the reference field set to point to the
4753 // new location, and the RSet updated. Otherwise we need to
4754 // use the the non-heap or metadata closures directly to copy
4755 // the referent object and update the pointer, while avoiding
4756 // updating the RSet.
4757
4758 if (_g1h->is_in_g1_reserved(p)) {
4759 _par_scan_state->push_on_queue(p);
4760 } else {
4761 assert(!Metaspace::contains((const void*)p),
4762 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4763 _copy_non_heap_obj_cl->do_oop(p);
4764 }
4765 }
4766 }
4767 };
4768
4769 // Serial drain queue closure. Called as the 'complete_gc'
4770 // closure for each discovered list in some of the
4771 // reference processing phases.
4772
4773 class G1STWDrainQueueClosure: public VoidClosure {
4774 protected:
4775 G1CollectedHeap* _g1h;
4776 G1ParScanThreadState* _par_scan_state;
4777
4778 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4779
4780 public:
4781 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4782 _g1h(g1h),
4783 _par_scan_state(pss)
4784 { }
4785
4786 void do_void() {
4787 G1ParScanThreadState* const pss = par_scan_state();
4788 pss->trim_queue();
4789 }
4790 };
4791
4792 // Parallel Reference Processing closures
4793
4794 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4795 // processing during G1 evacuation pauses.
4796
4797 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4798 private:
4799 G1CollectedHeap* _g1h;
4800 G1ParScanThreadStateSet* _pss;
4801 RefToScanQueueSet* _queues;
4802 WorkGang* _workers;
4803 uint _active_workers;
4804
4805 public:
4806 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4807 G1ParScanThreadStateSet* per_thread_states,
4808 WorkGang* workers,
4809 RefToScanQueueSet *task_queues,
4810 uint n_workers) :
4811 _g1h(g1h),
4812 _pss(per_thread_states),
4813 _queues(task_queues),
4814 _workers(workers),
4815 _active_workers(n_workers)
4816 {
4817 assert(n_workers > 0, "shouldn't call this otherwise");
4818 }
4819
4820 // Executes the given task using concurrent marking worker threads.
4821 virtual void execute(ProcessTask& task);
4822 virtual void execute(EnqueueTask& task);
4823 };
4824
4825 // Gang task for possibly parallel reference processing
4826
4827 class G1STWRefProcTaskProxy: public AbstractGangTask {
4828 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4829 ProcessTask& _proc_task;
4830 G1CollectedHeap* _g1h;
4831 G1ParScanThreadStateSet* _pss;
4832 RefToScanQueueSet* _task_queues;
4833 ParallelTaskTerminator* _terminator;
4834
4835 public:
4836 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4837 G1CollectedHeap* g1h,
4838 G1ParScanThreadStateSet* per_thread_states,
4839 RefToScanQueueSet *task_queues,
4840 ParallelTaskTerminator* terminator) :
4841 AbstractGangTask("Process reference objects in parallel"),
4842 _proc_task(proc_task),
4843 _g1h(g1h),
4844 _pss(per_thread_states),
4845 _task_queues(task_queues),
4846 _terminator(terminator)
4847 {}
4848
4849 virtual void work(uint worker_id) {
4850 // The reference processing task executed by a single worker.
4851 ResourceMark rm;
4852 HandleMark hm;
4853
4854 G1STWIsAliveClosure is_alive(_g1h);
4855
4856 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4857 pss->set_ref_processor(NULL);
4858
4859 // Keep alive closure.
4860 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4861
4862 // Complete GC closure
4863 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4864
4865 // Call the reference processing task's work routine.
4866 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4867
4868 // Note we cannot assert that the refs array is empty here as not all
4869 // of the processing tasks (specifically phase2 - pp2_work) execute
4870 // the complete_gc closure (which ordinarily would drain the queue) so
4871 // the queue may not be empty.
4872 }
4873 };
4874
4875 // Driver routine for parallel reference processing.
4876 // Creates an instance of the ref processing gang
4877 // task and has the worker threads execute it.
4878 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4879 assert(_workers != NULL, "Need parallel worker threads.");
4880
4881 ParallelTaskTerminator terminator(_active_workers, _queues);
4882 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4883
4884 _workers->run_task(&proc_task_proxy);
4885 }
4886
4887 // Gang task for parallel reference enqueueing.
4888
4889 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4890 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4891 EnqueueTask& _enq_task;
4892
4893 public:
4894 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4895 AbstractGangTask("Enqueue reference objects in parallel"),
4896 _enq_task(enq_task)
4897 { }
4898
4899 virtual void work(uint worker_id) {
4900 _enq_task.work(worker_id);
4901 }
4902 };
4903
4904 // Driver routine for parallel reference enqueueing.
4905 // Creates an instance of the ref enqueueing gang
4906 // task and has the worker threads execute it.
4907
4908 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4909 assert(_workers != NULL, "Need parallel worker threads.");
4910
4911 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4912
4913 _workers->run_task(&enq_task_proxy);
4914 }
4915
4916 // End of weak reference support closures
4917
4918 // Abstract task used to preserve (i.e. copy) any referent objects
4919 // that are in the collection set and are pointed to by reference
4920 // objects discovered by the CM ref processor.
4921
4922 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4923 protected:
4924 G1CollectedHeap* _g1h;
4925 G1ParScanThreadStateSet* _pss;
4926 RefToScanQueueSet* _queues;
4927 ParallelTaskTerminator _terminator;
4928 uint _n_workers;
4929
4930 public:
4931 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4932 AbstractGangTask("ParPreserveCMReferents"),
4933 _g1h(g1h),
4934 _pss(per_thread_states),
4935 _queues(task_queues),
4936 _terminator(workers, _queues),
4937 _n_workers(workers)
4938 { }
4939
4940 void work(uint worker_id) {
4941 ResourceMark rm;
4942 HandleMark hm;
4943
4944 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4945 pss->set_ref_processor(NULL);
4946 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4947
4948 // Is alive closure
4949 G1AlwaysAliveClosure always_alive(_g1h);
4950
4951 // Copying keep alive closure. Applied to referent objects that need
4952 // to be copied.
4953 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4954
4955 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4956
4957 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4958 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4959
4960 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4961 // So this must be true - but assert just in case someone decides to
4962 // change the worker ids.
4963 assert(worker_id < limit, "sanity");
4964 assert(!rp->discovery_is_atomic(), "check this code");
4965
4966 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4967 for (uint idx = worker_id; idx < limit; idx += stride) {
4968 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4969
4970 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4971 while (iter.has_next()) {
4972 // Since discovery is not atomic for the CM ref processor, we
4973 // can see some null referent objects.
4974 iter.load_ptrs(DEBUG_ONLY(true));
4975 oop ref = iter.obj();
4976
4977 // This will filter nulls.
4978 if (iter.is_referent_alive()) {
4979 iter.make_referent_alive();
4980 }
4981 iter.move_to_next();
4982 }
4983 }
4984
4985 // Drain the queue - which may cause stealing
4986 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4987 drain_queue.do_void();
4988 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4989 assert(pss->queue_is_empty(), "should be");
4990 }
4991 };
4992
4993 // Weak Reference processing during an evacuation pause (part 1).
4994 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4995 double ref_proc_start = os::elapsedTime();
4996
4997 ReferenceProcessor* rp = _ref_processor_stw;
4998 assert(rp->discovery_enabled(), "should have been enabled");
4999
5000 // Any reference objects, in the collection set, that were 'discovered'
5001 // by the CM ref processor should have already been copied (either by
5002 // applying the external root copy closure to the discovered lists, or
5003 // by following an RSet entry).
5004 //
5005 // But some of the referents, that are in the collection set, that these
5006 // reference objects point to may not have been copied: the STW ref
5007 // processor would have seen that the reference object had already
5008 // been 'discovered' and would have skipped discovering the reference,
5009 // but would not have treated the reference object as a regular oop.
5010 // As a result the copy closure would not have been applied to the
5011 // referent object.
5012 //
5013 // We need to explicitly copy these referent objects - the references
5014 // will be processed at the end of remarking.
5015 //
5016 // We also need to do this copying before we process the reference
5017 // objects discovered by the STW ref processor in case one of these
5018 // referents points to another object which is also referenced by an
5019 // object discovered by the STW ref processor.
5020
5021 uint no_of_gc_workers = workers()->active_workers();
5022
5023 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5024 per_thread_states,
5025 no_of_gc_workers,
5026 _task_queues);
5027
5028 workers()->run_task(&keep_cm_referents);
5029
5030 // Closure to test whether a referent is alive.
5031 G1STWIsAliveClosure is_alive(this);
5032
5033 // Even when parallel reference processing is enabled, the processing
5034 // of JNI refs is serial and performed serially by the current thread
5035 // rather than by a worker. The following PSS will be used for processing
5036 // JNI refs.
5037
5038 // Use only a single queue for this PSS.
5039 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5040 pss->set_ref_processor(NULL);
5041 assert(pss->queue_is_empty(), "pre-condition");
5042
5043 // Keep alive closure.
5044 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5045
5046 // Serial Complete GC closure
5047 G1STWDrainQueueClosure drain_queue(this, pss);
5048
5049 // Setup the soft refs policy...
5050 rp->setup_policy(false);
5051
5052 ReferenceProcessorStats stats;
5053 if (!rp->processing_is_mt()) {
5054 // Serial reference processing...
5055 stats = rp->process_discovered_references(&is_alive,
5056 &keep_alive,
5057 &drain_queue,
5058 NULL,
5059 _gc_timer_stw);
5060 } else {
5061 // Parallel reference processing
5062 assert(rp->num_q() == no_of_gc_workers, "sanity");
5063 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5064
5065 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5066 stats = rp->process_discovered_references(&is_alive,
5067 &keep_alive,
5068 &drain_queue,
5069 &par_task_executor,
5070 _gc_timer_stw);
5071 }
5072
5073 _gc_tracer_stw->report_gc_reference_stats(stats);
5074
5075 // We have completed copying any necessary live referent objects.
5076 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5077
5078 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5079 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5080 }
5081
5082 // Weak Reference processing during an evacuation pause (part 2).
5083 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5084 double ref_enq_start = os::elapsedTime();
5085
5086 ReferenceProcessor* rp = _ref_processor_stw;
5087 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5088
5089 // Now enqueue any remaining on the discovered lists on to
5090 // the pending list.
5091 if (!rp->processing_is_mt()) {
5092 // Serial reference processing...
5093 rp->enqueue_discovered_references();
5094 } else {
5095 // Parallel reference enqueueing
5096
5097 uint n_workers = workers()->active_workers();
5098
5099 assert(rp->num_q() == n_workers, "sanity");
5100 assert(n_workers <= rp->max_num_q(), "sanity");
5101
5102 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5103 rp->enqueue_discovered_references(&par_task_executor);
5104 }
5105
5106 rp->verify_no_references_recorded();
5107 assert(!rp->discovery_enabled(), "should have been disabled");
5108
5109 // FIXME
5110 // CM's reference processing also cleans up the string and symbol tables.
5111 // Should we do that here also? We could, but it is a serial operation
5112 // and could significantly increase the pause time.
5113
5114 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5115 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5116 }
5117
5118 void G1CollectedHeap::pre_evacuate_collection_set() {
5119 _expand_heap_after_alloc_failure = true;
5120 _evacuation_failed = false;
5121
5122 // Disable the hot card cache.
5123 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5124 hot_card_cache->reset_hot_cache_claimed_index();
5125 hot_card_cache->set_use_cache(false);
5126
5127 }
5128
5129 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5130 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5131
5132 // Should G1EvacuationFailureALot be in effect for this GC?
5133 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5134
5135 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5136 double start_par_time_sec = os::elapsedTime();
5137 double end_par_time_sec;
5138
5139 {
5140 const uint n_workers = workers()->active_workers();
5141 G1RootProcessor root_processor(this, n_workers);
5142 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5143 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5144 if (collector_state()->during_initial_mark_pause()) {
5145 ClassLoaderDataGraph::clear_claimed_marks();
5146 }
5147
5148 // The individual threads will set their evac-failure closures.
5149 if (PrintTerminationStats) {
5150 print_termination_stats_hdr(gclog_or_tty);
5151 }
5152
5153 workers()->run_task(&g1_par_task);
5154 end_par_time_sec = os::elapsedTime();
5155
5156 // Closing the inner scope will execute the destructor
5157 // for the G1RootProcessor object. We record the current
5158 // elapsed time before closing the scope so that time
5159 // taken for the destructor is NOT included in the
5160 // reported parallel time.
5161 }
5162
5163 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5164
5165 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5166 phase_times->record_par_time(par_time_ms);
5167
5168 double code_root_fixup_time_ms =
5169 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5170 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5171
5172 // Process any discovered reference objects - we have
5173 // to do this _before_ we retire the GC alloc regions
5174 // as we may have to copy some 'reachable' referent
5175 // objects (and their reachable sub-graphs) that were
5176 // not copied during the pause.
5177 process_discovered_references(per_thread_states);
5178
5179 if (G1StringDedup::is_enabled()) {
5180 double fixup_start = os::elapsedTime();
5181
5182 G1STWIsAliveClosure is_alive(this);
5183 G1KeepAliveClosure keep_alive(this);
5184 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5185
5186 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5187 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5188 }
5189
5190 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5191
5192 if (evacuation_failed()) {
5193 remove_self_forwarding_pointers();
5194
5195 // Reset the G1EvacuationFailureALot counters and flags
5196 // Note: the values are reset only when an actual
5197 // evacuation failure occurs.
5198 NOT_PRODUCT(reset_evacuation_should_fail();)
5199 }
5200
5201 // Enqueue any remaining references remaining on the STW
5202 // reference processor's discovered lists. We need to do
5203 // this after the card table is cleaned (and verified) as
5204 // the act of enqueueing entries on to the pending list
5205 // will log these updates (and dirty their associated
5206 // cards). We need these updates logged to update any
5207 // RSets.
5208 enqueue_discovered_references(per_thread_states);
5209 }
5210
5211 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5212 _allocator->release_gc_alloc_regions(evacuation_info);
5213
5214 per_thread_states->flush();
5215
5216 record_obj_copy_mem_stats();
5217
5218 _survivor_evac_stats.adjust_desired_plab_sz();
5219 _old_evac_stats.adjust_desired_plab_sz();
5220
5221 // Reset and re-enable the hot card cache.
5222 // Note the counts for the cards in the regions in the
5223 // collection set are reset when the collection set is freed.
5224 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5225 hot_card_cache->reset_hot_cache();
5226 hot_card_cache->set_use_cache(true);
5227
5228 purge_code_root_memory();
5229
5230 redirty_logged_cards();
5231 #if defined(COMPILER2) || INCLUDE_JVMCI
5232 DerivedPointerTable::update_pointers();
5233 #endif
5234 }
5235
5236 void G1CollectedHeap::record_obj_copy_mem_stats() {
5237 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5238 create_g1_evac_summary(&_old_evac_stats));
5239 }
5240
5241 void G1CollectedHeap::free_region(HeapRegion* hr,
5242 FreeRegionList* free_list,
5243 bool par,
5244 bool locked) {
5245 assert(!hr->is_free(), "the region should not be free");
5246 assert(!hr->is_empty(), "the region should not be empty");
5247 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5248 assert(free_list != NULL, "pre-condition");
5249
5250 if (G1VerifyBitmaps) {
5251 MemRegion mr(hr->bottom(), hr->end());
5252 concurrent_mark()->clearRangePrevBitmap(mr);
5253 }
5254
5255 // Clear the card counts for this region.
5256 // Note: we only need to do this if the region is not young
5257 // (since we don't refine cards in young regions).
5258 if (!hr->is_young()) {
5259 _cg1r->hot_card_cache()->reset_card_counts(hr);
5260 }
5261 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5262 free_list->add_ordered(hr);
5263 }
5264
5265 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5266 FreeRegionList* free_list,
5267 bool par) {
5268 assert(hr->is_humongous(), "this is only for humongous regions");
5269 assert(free_list != NULL, "pre-condition");
5270 hr->clear_humongous();
5271 free_region(hr, free_list, par);
5272 }
5273
5274 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5275 const HeapRegionSetCount& humongous_regions_removed) {
5276 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5277 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5278 _old_set.bulk_remove(old_regions_removed);
5279 _humongous_set.bulk_remove(humongous_regions_removed);
5280 }
5281
5282 }
5283
5284 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5285 assert(list != NULL, "list can't be null");
5286 if (!list->is_empty()) {
5287 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5288 _hrm.insert_list_into_free_list(list);
5289 }
5290 }
5291
5292 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5293 decrease_used(bytes);
5294 }
5295
5296 class G1ParCleanupCTTask : public AbstractGangTask {
5297 G1SATBCardTableModRefBS* _ct_bs;
5298 G1CollectedHeap* _g1h;
5299 HeapRegion* volatile _su_head;
5300 public:
5301 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5302 G1CollectedHeap* g1h) :
5303 AbstractGangTask("G1 Par Cleanup CT Task"),
5304 _ct_bs(ct_bs), _g1h(g1h) { }
5305
5306 void work(uint worker_id) {
5307 HeapRegion* r;
5308 while (r = _g1h->pop_dirty_cards_region()) {
5309 clear_cards(r);
5310 }
5311 }
5312
5313 void clear_cards(HeapRegion* r) {
5314 // Cards of the survivors should have already been dirtied.
5315 if (!r->is_survivor()) {
5316 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5317 }
5318 }
5319 };
5320
5321 #ifndef PRODUCT
5322 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5323 G1CollectedHeap* _g1h;
5324 G1SATBCardTableModRefBS* _ct_bs;
5325 public:
5326 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5327 : _g1h(g1h), _ct_bs(ct_bs) { }
5328 virtual bool doHeapRegion(HeapRegion* r) {
5329 if (r->is_survivor()) {
5330 _g1h->verify_dirty_region(r);
5331 } else {
5332 _g1h->verify_not_dirty_region(r);
5333 }
5334 return false;
5335 }
5336 };
5337
5338 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5339 // All of the region should be clean.
5340 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5341 MemRegion mr(hr->bottom(), hr->end());
5342 ct_bs->verify_not_dirty_region(mr);
5343 }
5344
5345 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5346 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5347 // dirty allocated blocks as they allocate them. The thread that
5348 // retires each region and replaces it with a new one will do a
5349 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5350 // not dirty that area (one less thing to have to do while holding
5351 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5352 // is dirty.
5353 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5354 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5355 if (hr->is_young()) {
5356 ct_bs->verify_g1_young_region(mr);
5357 } else {
5358 ct_bs->verify_dirty_region(mr);
5359 }
5360 }
5361
5362 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5363 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5364 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5365 verify_dirty_region(hr);
5366 }
5367 }
5368
5369 void G1CollectedHeap::verify_dirty_young_regions() {
5370 verify_dirty_young_list(_young_list->first_region());
5371 }
5372
5373 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5374 HeapWord* tams, HeapWord* end) {
5375 guarantee(tams <= end,
5376 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5377 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5378 if (result < end) {
5379 gclog_or_tty->cr();
5380 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5381 bitmap_name, p2i(result));
5382 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5383 bitmap_name, p2i(tams), p2i(end));
5384 return false;
5385 }
5386 return true;
5387 }
5388
5389 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5390 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5391 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5392
5393 HeapWord* bottom = hr->bottom();
5394 HeapWord* ptams = hr->prev_top_at_mark_start();
5395 HeapWord* ntams = hr->next_top_at_mark_start();
5396 HeapWord* end = hr->end();
5397
5398 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5399
5400 bool res_n = true;
5401 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5402 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5403 // if we happen to be in that state.
5404 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5405 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5406 }
5407 if (!res_p || !res_n) {
5408 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5409 HR_FORMAT_PARAMS(hr));
5410 gclog_or_tty->print_cr("#### Caller: %s", caller);
5411 return false;
5412 }
5413 return true;
5414 }
5415
5416 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5417 if (!G1VerifyBitmaps) return;
5418
5419 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5420 }
5421
5422 class G1VerifyBitmapClosure : public HeapRegionClosure {
5423 private:
5424 const char* _caller;
5425 G1CollectedHeap* _g1h;
5426 bool _failures;
5427
5428 public:
5429 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5430 _caller(caller), _g1h(g1h), _failures(false) { }
5431
5432 bool failures() { return _failures; }
5433
5434 virtual bool doHeapRegion(HeapRegion* hr) {
5435 bool result = _g1h->verify_bitmaps(_caller, hr);
5436 if (!result) {
5437 _failures = true;
5438 }
5439 return false;
5440 }
5441 };
5442
5443 void G1CollectedHeap::check_bitmaps(const char* caller) {
5444 if (!G1VerifyBitmaps) return;
5445
5446 G1VerifyBitmapClosure cl(caller, this);
5447 heap_region_iterate(&cl);
5448 guarantee(!cl.failures(), "bitmap verification");
5449 }
5450
5451 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5452 private:
5453 bool _failures;
5454 public:
5455 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5456
5457 virtual bool doHeapRegion(HeapRegion* hr) {
5458 uint i = hr->hrm_index();
5459 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5460 if (hr->is_humongous()) {
5461 if (hr->in_collection_set()) {
5462 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5463 _failures = true;
5464 return true;
5465 }
5466 if (cset_state.is_in_cset()) {
5467 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5468 _failures = true;
5469 return true;
5470 }
5471 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5472 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5473 _failures = true;
5474 return true;
5475 }
5476 } else {
5477 if (cset_state.is_humongous()) {
5478 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5479 _failures = true;
5480 return true;
5481 }
5482 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5483 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5484 hr->in_collection_set(), cset_state.value(), i);
5485 _failures = true;
5486 return true;
5487 }
5488 if (cset_state.is_in_cset()) {
5489 if (hr->is_young() != (cset_state.is_young())) {
5490 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5491 hr->is_young(), cset_state.value(), i);
5492 _failures = true;
5493 return true;
5494 }
5495 if (hr->is_old() != (cset_state.is_old())) {
5496 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5497 hr->is_old(), cset_state.value(), i);
5498 _failures = true;
5499 return true;
5500 }
5501 }
5502 }
5503 return false;
5504 }
5505
5506 bool failures() const { return _failures; }
5507 };
5508
5509 bool G1CollectedHeap::check_cset_fast_test() {
5510 G1CheckCSetFastTableClosure cl;
5511 _hrm.iterate(&cl);
5512 return !cl.failures();
5513 }
5514 #endif // PRODUCT
5515
5516 void G1CollectedHeap::cleanUpCardTable() {
5517 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5518 double start = os::elapsedTime();
5519
5520 {
5521 // Iterate over the dirty cards region list.
5522 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5523
5524 workers()->run_task(&cleanup_task);
5525 #ifndef PRODUCT
5526 if (G1VerifyCTCleanup || VerifyAfterGC) {
5527 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5528 heap_region_iterate(&cleanup_verifier);
5529 }
5530 #endif
5531 }
5532
5533 double elapsed = os::elapsedTime() - start;
5534 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5535 }
5536
5537 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5538 size_t pre_used = 0;
5539 FreeRegionList local_free_list("Local List for CSet Freeing");
5540
5541 double young_time_ms = 0.0;
5542 double non_young_time_ms = 0.0;
5543
5544 // Since the collection set is a superset of the the young list,
5545 // all we need to do to clear the young list is clear its
5546 // head and length, and unlink any young regions in the code below
5547 _young_list->clear();
5548
5549 G1CollectorPolicy* policy = g1_policy();
5550
5551 double start_sec = os::elapsedTime();
5552 bool non_young = true;
5553
5554 HeapRegion* cur = cs_head;
5555 int age_bound = -1;
5556 size_t rs_lengths = 0;
5557
5558 while (cur != NULL) {
5559 assert(!is_on_master_free_list(cur), "sanity");
5560 if (non_young) {
5561 if (cur->is_young()) {
5562 double end_sec = os::elapsedTime();
5563 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5564 non_young_time_ms += elapsed_ms;
5565
5566 start_sec = os::elapsedTime();
5567 non_young = false;
5568 }
5569 } else {
5570 if (!cur->is_young()) {
5571 double end_sec = os::elapsedTime();
5572 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5573 young_time_ms += elapsed_ms;
5574
5575 start_sec = os::elapsedTime();
5576 non_young = true;
5577 }
5578 }
5579
5580 rs_lengths += cur->rem_set()->occupied_locked();
5581
5582 HeapRegion* next = cur->next_in_collection_set();
5583 assert(cur->in_collection_set(), "bad CS");
5584 cur->set_next_in_collection_set(NULL);
5585 clear_in_cset(cur);
5586
5587 if (cur->is_young()) {
5588 int index = cur->young_index_in_cset();
5589 assert(index != -1, "invariant");
5590 assert((uint) index < policy->young_cset_region_length(), "invariant");
5591 size_t words_survived = surviving_young_words[index];
5592 cur->record_surv_words_in_group(words_survived);
5593
5594 // At this point the we have 'popped' cur from the collection set
5595 // (linked via next_in_collection_set()) but it is still in the
5596 // young list (linked via next_young_region()). Clear the
5597 // _next_young_region field.
5598 cur->set_next_young_region(NULL);
5599 } else {
5600 int index = cur->young_index_in_cset();
5601 assert(index == -1, "invariant");
5602 }
5603
5604 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5605 (!cur->is_young() && cur->young_index_in_cset() == -1),
5606 "invariant" );
5607
5608 if (!cur->evacuation_failed()) {
5609 MemRegion used_mr = cur->used_region();
5610
5611 // And the region is empty.
5612 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5613 pre_used += cur->used();
5614 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5615 } else {
5616 cur->uninstall_surv_rate_group();
5617 if (cur->is_young()) {
5618 cur->set_young_index_in_cset(-1);
5619 }
5620 cur->set_evacuation_failed(false);
5621 // The region is now considered to be old.
5622 cur->set_old();
5623 // Do some allocation statistics accounting. Regions that failed evacuation
5624 // are always made old, so there is no need to update anything in the young
5625 // gen statistics, but we need to update old gen statistics.
5626 size_t used_words = cur->marked_bytes() / HeapWordSize;
5627 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5628 _old_set.add(cur);
5629 evacuation_info.increment_collectionset_used_after(cur->used());
5630 }
5631 cur = next;
5632 }
5633
5634 evacuation_info.set_regions_freed(local_free_list.length());
5635 policy->record_max_rs_lengths(rs_lengths);
5636 policy->cset_regions_freed();
5637
5638 double end_sec = os::elapsedTime();
5639 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5640
5641 if (non_young) {
5642 non_young_time_ms += elapsed_ms;
5643 } else {
5644 young_time_ms += elapsed_ms;
5645 }
5646
5647 prepend_to_freelist(&local_free_list);
5648 decrement_summary_bytes(pre_used);
5649 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5650 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5651 }
5652
5653 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5654 private:
5655 FreeRegionList* _free_region_list;
5656 HeapRegionSet* _proxy_set;
5657 HeapRegionSetCount _humongous_regions_removed;
5658 size_t _freed_bytes;
5659 public:
5660
5661 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5662 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5663 }
5664
5665 virtual bool doHeapRegion(HeapRegion* r) {
5666 if (!r->is_starts_humongous()) {
5667 return false;
5668 }
5669
5670 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5671
5672 oop obj = (oop)r->bottom();
5673 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5674
5675 // The following checks whether the humongous object is live are sufficient.
5676 // The main additional check (in addition to having a reference from the roots
5677 // or the young gen) is whether the humongous object has a remembered set entry.
5678 //
5679 // A humongous object cannot be live if there is no remembered set for it
5680 // because:
5681 // - there can be no references from within humongous starts regions referencing
5682 // the object because we never allocate other objects into them.
5683 // (I.e. there are no intra-region references that may be missed by the
5684 // remembered set)
5685 // - as soon there is a remembered set entry to the humongous starts region
5686 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5687 // until the end of a concurrent mark.
5688 //
5689 // It is not required to check whether the object has been found dead by marking
5690 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5691 // all objects allocated during that time are considered live.
5692 // SATB marking is even more conservative than the remembered set.
5693 // So if at this point in the collection there is no remembered set entry,
5694 // nobody has a reference to it.
5695 // At the start of collection we flush all refinement logs, and remembered sets
5696 // are completely up-to-date wrt to references to the humongous object.
5697 //
5698 // Other implementation considerations:
5699 // - never consider object arrays at this time because they would pose
5700 // considerable effort for cleaning up the the remembered sets. This is
5701 // required because stale remembered sets might reference locations that
5702 // are currently allocated into.
5703 uint region_idx = r->hrm_index();
5704 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5705 !r->rem_set()->is_empty()) {
5706
5707 if (G1TraceEagerReclaimHumongousObjects) {
5708 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",
5709 region_idx,
5710 (size_t)obj->size() * HeapWordSize,
5711 p2i(r->bottom()),
5712 r->rem_set()->occupied(),
5713 r->rem_set()->strong_code_roots_list_length(),
5714 next_bitmap->isMarked(r->bottom()),
5715 g1h->is_humongous_reclaim_candidate(region_idx),
5716 obj->is_typeArray()
5717 );
5718 }
5719
5720 return false;
5721 }
5722
5723 guarantee(obj->is_typeArray(),
5724 "Only eagerly reclaiming type arrays is supported, but the object "
5725 PTR_FORMAT " is not.", p2i(r->bottom()));
5726
5727 if (G1TraceEagerReclaimHumongousObjects) {
5728 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",
5729 region_idx,
5730 (size_t)obj->size() * HeapWordSize,
5731 p2i(r->bottom()),
5732 r->rem_set()->occupied(),
5733 r->rem_set()->strong_code_roots_list_length(),
5734 next_bitmap->isMarked(r->bottom()),
5735 g1h->is_humongous_reclaim_candidate(region_idx),
5736 obj->is_typeArray()
5737 );
5738 }
5739 // Need to clear mark bit of the humongous object if already set.
5740 if (next_bitmap->isMarked(r->bottom())) {
5741 next_bitmap->clear(r->bottom());
5742 }
5743 do {
5744 HeapRegion* next = g1h->next_region_in_humongous(r);
5745 _freed_bytes += r->used();
5746 r->set_containing_set(NULL);
5747 _humongous_regions_removed.increment(1u, r->capacity());
5748 g1h->free_humongous_region(r, _free_region_list, false);
5749 r = next;
5750 } while (r != NULL);
5751
5752 return false;
5753 }
5754
5755 HeapRegionSetCount& humongous_free_count() {
5756 return _humongous_regions_removed;
5757 }
5758
5759 size_t bytes_freed() const {
5760 return _freed_bytes;
5761 }
5762
5763 size_t humongous_reclaimed() const {
5764 return _humongous_regions_removed.length();
5765 }
5766 };
5767
5768 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5769 assert_at_safepoint(true);
5770
5771 if (!G1EagerReclaimHumongousObjects ||
5772 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5773 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5774 return;
5775 }
5776
5777 double start_time = os::elapsedTime();
5778
5779 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5780
5781 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5782 heap_region_iterate(&cl);
5783
5784 HeapRegionSetCount empty_set;
5785 remove_from_old_sets(empty_set, cl.humongous_free_count());
5786
5787 G1HRPrinter* hrp = hr_printer();
5788 if (hrp->is_active()) {
5789 FreeRegionListIterator iter(&local_cleanup_list);
5790 while (iter.more_available()) {
5791 HeapRegion* hr = iter.get_next();
5792 hrp->cleanup(hr);
5793 }
5794 }
5795
5796 prepend_to_freelist(&local_cleanup_list);
5797 decrement_summary_bytes(cl.bytes_freed());
5798
5799 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5800 cl.humongous_reclaimed());
5801 }
5802
5803 // This routine is similar to the above but does not record
5804 // any policy statistics or update free lists; we are abandoning
5805 // the current incremental collection set in preparation of a
5806 // full collection. After the full GC we will start to build up
5807 // the incremental collection set again.
5808 // This is only called when we're doing a full collection
5809 // and is immediately followed by the tearing down of the young list.
5810
5811 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5812 HeapRegion* cur = cs_head;
5813
5814 while (cur != NULL) {
5815 HeapRegion* next = cur->next_in_collection_set();
5816 assert(cur->in_collection_set(), "bad CS");
5817 cur->set_next_in_collection_set(NULL);
5818 clear_in_cset(cur);
5819 cur->set_young_index_in_cset(-1);
5820 cur = next;
5821 }
5822 }
5823
5824 void G1CollectedHeap::set_free_regions_coming() {
5825 if (G1ConcRegionFreeingVerbose) {
5826 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5827 "setting free regions coming");
5828 }
5829
5830 assert(!free_regions_coming(), "pre-condition");
5831 _free_regions_coming = true;
5832 }
5833
5834 void G1CollectedHeap::reset_free_regions_coming() {
5835 assert(free_regions_coming(), "pre-condition");
5836
5837 {
5838 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5839 _free_regions_coming = false;
5840 SecondaryFreeList_lock->notify_all();
5841 }
5842
5843 if (G1ConcRegionFreeingVerbose) {
5844 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5845 "reset free regions coming");
5846 }
5847 }
5848
5849 void G1CollectedHeap::wait_while_free_regions_coming() {
5850 // Most of the time we won't have to wait, so let's do a quick test
5851 // first before we take the lock.
5852 if (!free_regions_coming()) {
5853 return;
5854 }
5855
5856 if (G1ConcRegionFreeingVerbose) {
5857 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5858 "waiting for free regions");
5859 }
5860
5861 {
5862 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5863 while (free_regions_coming()) {
5864 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5865 }
5866 }
5867
5868 if (G1ConcRegionFreeingVerbose) {
5869 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5870 "done waiting for free regions");
5871 }
5872 }
5873
5874 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5875 return _allocator->is_retained_old_region(hr);
5876 }
5877
5878 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5879 _young_list->push_region(hr);
5880 }
5881
5882 class NoYoungRegionsClosure: public HeapRegionClosure {
5883 private:
5884 bool _success;
5885 public:
5886 NoYoungRegionsClosure() : _success(true) { }
5887 bool doHeapRegion(HeapRegion* r) {
5888 if (r->is_young()) {
5889 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5890 p2i(r->bottom()), p2i(r->end()));
5891 _success = false;
5892 }
5893 return false;
5894 }
5895 bool success() { return _success; }
5896 };
5897
5898 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5899 bool ret = _young_list->check_list_empty(check_sample);
5900
5901 if (check_heap) {
5902 NoYoungRegionsClosure closure;
5903 heap_region_iterate(&closure);
5904 ret = ret && closure.success();
5905 }
5906
5907 return ret;
5908 }
5909
5910 class TearDownRegionSetsClosure : public HeapRegionClosure {
5911 private:
5912 HeapRegionSet *_old_set;
5913
5914 public:
5915 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5916
5917 bool doHeapRegion(HeapRegion* r) {
5918 if (r->is_old()) {
5919 _old_set->remove(r);
5920 } else {
5921 // We ignore free regions, we'll empty the free list afterwards.
5922 // We ignore young regions, we'll empty the young list afterwards.
5923 // We ignore humongous regions, we're not tearing down the
5924 // humongous regions set.
5925 assert(r->is_free() || r->is_young() || r->is_humongous(),
5926 "it cannot be another type");
5927 }
5928 return false;
5929 }
5930
5931 ~TearDownRegionSetsClosure() {
5932 assert(_old_set->is_empty(), "post-condition");
5933 }
5934 };
5935
5936 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5937 assert_at_safepoint(true /* should_be_vm_thread */);
5938
5939 if (!free_list_only) {
5940 TearDownRegionSetsClosure cl(&_old_set);
5941 heap_region_iterate(&cl);
5942
5943 // Note that emptying the _young_list is postponed and instead done as
5944 // the first step when rebuilding the regions sets again. The reason for
5945 // this is that during a full GC string deduplication needs to know if
5946 // a collected region was young or old when the full GC was initiated.
5947 }
5948 _hrm.remove_all_free_regions();
5949 }
5950
5951 void G1CollectedHeap::increase_used(size_t bytes) {
5952 _summary_bytes_used += bytes;
5953 }
5954
5955 void G1CollectedHeap::decrease_used(size_t bytes) {
5956 assert(_summary_bytes_used >= bytes,
5957 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5958 _summary_bytes_used, bytes);
5959 _summary_bytes_used -= bytes;
5960 }
5961
5962 void G1CollectedHeap::set_used(size_t bytes) {
5963 _summary_bytes_used = bytes;
5964 }
5965
5966 class RebuildRegionSetsClosure : public HeapRegionClosure {
5967 private:
5968 bool _free_list_only;
5969 HeapRegionSet* _old_set;
5970 HeapRegionManager* _hrm;
5971 size_t _total_used;
5972
5973 public:
5974 RebuildRegionSetsClosure(bool free_list_only,
5975 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5976 _free_list_only(free_list_only),
5977 _old_set(old_set), _hrm(hrm), _total_used(0) {
5978 assert(_hrm->num_free_regions() == 0, "pre-condition");
5979 if (!free_list_only) {
5980 assert(_old_set->is_empty(), "pre-condition");
5981 }
5982 }
5983
5984 bool doHeapRegion(HeapRegion* r) {
5985 if (r->is_empty()) {
5986 // Add free regions to the free list
5987 r->set_free();
5988 r->set_allocation_context(AllocationContext::system());
5989 _hrm->insert_into_free_list(r);
5990 } else if (!_free_list_only) {
5991 assert(!r->is_young(), "we should not come across young regions");
5992
5993 if (r->is_humongous()) {
5994 // We ignore humongous regions. We left the humongous set unchanged.
5995 } else {
5996 // Objects that were compacted would have ended up on regions
5997 // that were previously old or free. Archive regions (which are
5998 // old) will not have been touched.
5999 assert(r->is_free() || r->is_old(), "invariant");
6000 // We now consider them old, so register as such. Leave
6001 // archive regions set that way, however, while still adding
6002 // them to the old set.
6003 if (!r->is_archive()) {
6004 r->set_old();
6005 }
6006 _old_set->add(r);
6007 }
6008 _total_used += r->used();
6009 }
6010
6011 return false;
6012 }
6013
6014 size_t total_used() {
6015 return _total_used;
6016 }
6017 };
6018
6019 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6020 assert_at_safepoint(true /* should_be_vm_thread */);
6021
6022 if (!free_list_only) {
6023 _young_list->empty_list();
6024 }
6025
6026 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6027 heap_region_iterate(&cl);
6028
6029 if (!free_list_only) {
6030 set_used(cl.total_used());
6031 if (_archive_allocator != NULL) {
6032 _archive_allocator->clear_used();
6033 }
6034 }
6035 assert(used_unlocked() == recalculate_used(),
6036 "inconsistent used_unlocked(), "
6037 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6038 used_unlocked(), recalculate_used());
6039 }
6040
6041 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6042 _refine_cte_cl->set_concurrent(concurrent);
6043 }
6044
6045 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6046 HeapRegion* hr = heap_region_containing(p);
6047 return hr->is_in(p);
6048 }
6049
6050 // Methods for the mutator alloc region
6051
6052 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6053 bool force) {
6054 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6055 assert(!force || g1_policy()->can_expand_young_list(),
6056 "if force is true we should be able to expand the young list");
6057 bool young_list_full = g1_policy()->is_young_list_full();
6058 if (force || !young_list_full) {
6059 HeapRegion* new_alloc_region = new_region(word_size,
6060 false /* is_old */,
6061 false /* do_expand */);
6062 if (new_alloc_region != NULL) {
6063 set_region_short_lived_locked(new_alloc_region);
6064 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6065 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6066 return new_alloc_region;
6067 }
6068 }
6069 return NULL;
6070 }
6071
6072 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6073 size_t allocated_bytes) {
6074 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6075 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6076
6077 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6078 increase_used(allocated_bytes);
6079 _hr_printer.retire(alloc_region);
6080 // We update the eden sizes here, when the region is retired,
6081 // instead of when it's allocated, since this is the point that its
6082 // used space has been recored in _summary_bytes_used.
6083 g1mm()->update_eden_size();
6084 }
6085
6086 // Methods for the GC alloc regions
6087
6088 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6089 uint count,
6090 InCSetState dest) {
6091 assert(FreeList_lock->owned_by_self(), "pre-condition");
6092
6093 if (count < g1_policy()->max_regions(dest)) {
6094 const bool is_survivor = (dest.is_young());
6095 HeapRegion* new_alloc_region = new_region(word_size,
6096 !is_survivor,
6097 true /* do_expand */);
6098 if (new_alloc_region != NULL) {
6099 // We really only need to do this for old regions given that we
6100 // should never scan survivors. But it doesn't hurt to do it
6101 // for survivors too.
6102 new_alloc_region->record_timestamp();
6103 if (is_survivor) {
6104 new_alloc_region->set_survivor();
6105 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6106 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6107 } else {
6108 new_alloc_region->set_old();
6109 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6110 check_bitmaps("Old Region Allocation", new_alloc_region);
6111 }
6112 bool during_im = collector_state()->during_initial_mark_pause();
6113 new_alloc_region->note_start_of_copying(during_im);
6114 return new_alloc_region;
6115 }
6116 }
6117 return NULL;
6118 }
6119
6120 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6121 size_t allocated_bytes,
6122 InCSetState dest) {
6123 bool during_im = collector_state()->during_initial_mark_pause();
6124 alloc_region->note_end_of_copying(during_im);
6125 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6126 if (dest.is_young()) {
6127 young_list()->add_survivor_region(alloc_region);
6128 } else {
6129 _old_set.add(alloc_region);
6130 }
6131 _hr_printer.retire(alloc_region);
6132 }
6133
6134 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6135 bool expanded = false;
6136 uint index = _hrm.find_highest_free(&expanded);
6137
6138 if (index != G1_NO_HRM_INDEX) {
6139 if (expanded) {
6140 ergo_verbose1(ErgoHeapSizing,
6141 "attempt heap expansion",
6142 ergo_format_reason("requested address range outside heap bounds")
6143 ergo_format_byte("region size"),
6144 HeapRegion::GrainWords * HeapWordSize);
6145 }
6146 _hrm.allocate_free_regions_starting_at(index, 1);
6147 return region_at(index);
6148 }
6149 return NULL;
6150 }
6151
6152 // Heap region set verification
6153
6154 class VerifyRegionListsClosure : public HeapRegionClosure {
6155 private:
6156 HeapRegionSet* _old_set;
6157 HeapRegionSet* _humongous_set;
6158 HeapRegionManager* _hrm;
6159
6160 public:
6161 HeapRegionSetCount _old_count;
6162 HeapRegionSetCount _humongous_count;
6163 HeapRegionSetCount _free_count;
6164
6165 VerifyRegionListsClosure(HeapRegionSet* old_set,
6166 HeapRegionSet* humongous_set,
6167 HeapRegionManager* hrm) :
6168 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6169 _old_count(), _humongous_count(), _free_count(){ }
6170
6171 bool doHeapRegion(HeapRegion* hr) {
6172 if (hr->is_young()) {
6173 // TODO
6174 } else if (hr->is_humongous()) {
6175 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6176 _humongous_count.increment(1u, hr->capacity());
6177 } else if (hr->is_empty()) {
6178 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6179 _free_count.increment(1u, hr->capacity());
6180 } else if (hr->is_old()) {
6181 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6182 _old_count.increment(1u, hr->capacity());
6183 } else {
6184 // There are no other valid region types. Check for one invalid
6185 // one we can identify: pinned without old or humongous set.
6186 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6187 ShouldNotReachHere();
6188 }
6189 return false;
6190 }
6191
6192 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6193 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6194 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6195 old_set->total_capacity_bytes(), _old_count.capacity());
6196
6197 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6198 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6199 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6200
6201 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());
6202 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6203 free_list->total_capacity_bytes(), _free_count.capacity());
6204 }
6205 };
6206
6207 void G1CollectedHeap::verify_region_sets() {
6208 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6209
6210 // First, check the explicit lists.
6211 _hrm.verify();
6212 {
6213 // Given that a concurrent operation might be adding regions to
6214 // the secondary free list we have to take the lock before
6215 // verifying it.
6216 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6217 _secondary_free_list.verify_list();
6218 }
6219
6220 // If a concurrent region freeing operation is in progress it will
6221 // be difficult to correctly attributed any free regions we come
6222 // across to the correct free list given that they might belong to
6223 // one of several (free_list, secondary_free_list, any local lists,
6224 // etc.). So, if that's the case we will skip the rest of the
6225 // verification operation. Alternatively, waiting for the concurrent
6226 // operation to complete will have a non-trivial effect on the GC's
6227 // operation (no concurrent operation will last longer than the
6228 // interval between two calls to verification) and it might hide
6229 // any issues that we would like to catch during testing.
6230 if (free_regions_coming()) {
6231 return;
6232 }
6233
6234 // Make sure we append the secondary_free_list on the free_list so
6235 // that all free regions we will come across can be safely
6236 // attributed to the free_list.
6237 append_secondary_free_list_if_not_empty_with_lock();
6238
6239 // Finally, make sure that the region accounting in the lists is
6240 // consistent with what we see in the heap.
6241
6242 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6243 heap_region_iterate(&cl);
6244 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6245 }
6246
6247 // Optimized nmethod scanning
6248
6249 class RegisterNMethodOopClosure: public OopClosure {
6250 G1CollectedHeap* _g1h;
6251 nmethod* _nm;
6252
6253 template <class T> void do_oop_work(T* p) {
6254 T heap_oop = oopDesc::load_heap_oop(p);
6255 if (!oopDesc::is_null(heap_oop)) {
6256 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6257 HeapRegion* hr = _g1h->heap_region_containing(obj);
6258 assert(!hr->is_continues_humongous(),
6259 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6260 " starting at " HR_FORMAT,
6261 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6262
6263 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6264 hr->add_strong_code_root_locked(_nm);
6265 }
6266 }
6267
6268 public:
6269 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6270 _g1h(g1h), _nm(nm) {}
6271
6272 void do_oop(oop* p) { do_oop_work(p); }
6273 void do_oop(narrowOop* p) { do_oop_work(p); }
6274 };
6275
6276 class UnregisterNMethodOopClosure: public OopClosure {
6277 G1CollectedHeap* _g1h;
6278 nmethod* _nm;
6279
6280 template <class T> void do_oop_work(T* p) {
6281 T heap_oop = oopDesc::load_heap_oop(p);
6282 if (!oopDesc::is_null(heap_oop)) {
6283 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6284 HeapRegion* hr = _g1h->heap_region_containing(obj);
6285 assert(!hr->is_continues_humongous(),
6286 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6287 " starting at " HR_FORMAT,
6288 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6289
6290 hr->remove_strong_code_root(_nm);
6291 }
6292 }
6293
6294 public:
6295 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6296 _g1h(g1h), _nm(nm) {}
6297
6298 void do_oop(oop* p) { do_oop_work(p); }
6299 void do_oop(narrowOop* p) { do_oop_work(p); }
6300 };
6301
6302 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6303 CollectedHeap::register_nmethod(nm);
6304
6305 guarantee(nm != NULL, "sanity");
6306 RegisterNMethodOopClosure reg_cl(this, nm);
6307 nm->oops_do(®_cl);
6308 }
6309
6310 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6311 CollectedHeap::unregister_nmethod(nm);
6312
6313 guarantee(nm != NULL, "sanity");
6314 UnregisterNMethodOopClosure reg_cl(this, nm);
6315 nm->oops_do(®_cl, true);
6316 }
6317
6318 void G1CollectedHeap::purge_code_root_memory() {
6319 double purge_start = os::elapsedTime();
6320 G1CodeRootSet::purge();
6321 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6322 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6323 }
6324
6325 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6326 G1CollectedHeap* _g1h;
6327
6328 public:
6329 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6330 _g1h(g1h) {}
6331
6332 void do_code_blob(CodeBlob* cb) {
6333 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6334 if (nm == NULL) {
6335 return;
6336 }
6337
6338 if (ScavengeRootsInCode) {
6339 _g1h->register_nmethod(nm);
6340 }
6341 }
6342 };
6343
6344 void G1CollectedHeap::rebuild_strong_code_roots() {
6345 RebuildStrongCodeRootClosure blob_cl(this);
6346 CodeCache::blobs_do(&blob_cl);
6347 }