1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootClosures.hpp"
48 #include "gc/g1/g1RootProcessor.hpp"
49 #include "gc/g1/g1StringDedup.hpp"
50 #include "gc/g1/g1YCTypes.hpp"
51 #include "gc/g1/heapRegion.inline.hpp"
52 #include "gc/g1/heapRegionRemSet.hpp"
53 #include "gc/g1/heapRegionSet.inline.hpp"
54 #include "gc/g1/suspendibleThreadSet.hpp"
55 #include "gc/g1/vm_operations_g1.hpp"
56 #include "gc/shared/gcHeapSummary.hpp"
57 #include "gc/shared/gcId.hpp"
58 #include "gc/shared/gcLocker.inline.hpp"
59 #include "gc/shared/gcTimer.hpp"
60 #include "gc/shared/gcTrace.hpp"
61 #include "gc/shared/gcTraceTime.hpp"
62 #include "gc/shared/generationSpec.hpp"
63 #include "gc/shared/isGCActiveMark.hpp"
64 #include "gc/shared/referenceProcessor.hpp"
65 #include "gc/shared/taskqueue.inline.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_processed;
116
117 public:
118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
119
120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
121 *card_ptr = CardTableModRefBS::dirty_card_val();
122 _num_processed++;
123 return true;
124 }
125
126 size_t num_processed() const { return _num_processed; }
127 };
128
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
141 {
142 // Claim the right to put the region on the dirty cards region list
143 // by installing a self pointer.
144 HeapRegion* next = hr->get_next_dirty_cards_region();
145 if (next == NULL) {
146 HeapRegion* res = (HeapRegion*)
147 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
148 NULL);
149 if (res == NULL) {
150 HeapRegion* head;
151 do {
152 // Put the region to the dirty cards region list.
153 head = _dirty_cards_region_list;
154 next = (HeapRegion*)
155 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
156 if (next == head) {
157 assert(hr->get_next_dirty_cards_region() == hr,
158 "hr->get_next_dirty_cards_region() != hr");
159 if (next == NULL) {
160 // The last region in the list points to itself.
161 hr->set_next_dirty_cards_region(hr);
162 } else {
163 hr->set_next_dirty_cards_region(next);
164 }
165 }
166 } while (next != head);
167 }
168 }
169 }
170
171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
172 {
173 HeapRegion* head;
174 HeapRegion* hr;
175 do {
176 head = _dirty_cards_region_list;
177 if (head == NULL) {
178 return NULL;
179 }
180 HeapRegion* new_head = head->get_next_dirty_cards_region();
181 if (head == new_head) {
182 // The last region.
183 new_head = NULL;
184 }
185 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
186 head);
187 } while (hr != head);
188 assert(hr != NULL, "invariant");
189 hr->set_next_dirty_cards_region(NULL);
190 return hr;
191 }
192
193 // Returns true if the reference points to an object that
194 // can move in an incremental collection.
195 bool G1CollectedHeap::is_scavengable(const void* p) {
196 HeapRegion* hr = heap_region_containing(p);
197 return !hr->is_pinned();
198 }
199
200 // Private methods.
201
202 HeapRegion*
203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
205 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
206 if (!_secondary_free_list.is_empty()) {
207 if (G1ConcRegionFreeingVerbose) {
208 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
209 "secondary_free_list has %u entries",
210 _secondary_free_list.length());
211 }
212 // It looks as if there are free regions available on the
213 // secondary_free_list. Let's move them to the free_list and try
214 // again to allocate from it.
215 append_secondary_free_list();
216
217 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
218 "empty we should have moved at least one entry to the free_list");
219 HeapRegion* res = _hrm.allocate_free_region(is_old);
220 if (G1ConcRegionFreeingVerbose) {
221 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
222 "allocated " HR_FORMAT " from secondary_free_list",
223 HR_FORMAT_PARAMS(res));
224 }
225 return res;
226 }
227
228 // Wait here until we get notified either when (a) there are no
229 // more free regions coming or (b) some regions have been moved on
230 // the secondary_free_list.
231 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
232 }
233
234 if (G1ConcRegionFreeingVerbose) {
235 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
236 "could not allocate from secondary_free_list");
237 }
238 return NULL;
239 }
240
241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
242 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
243 "the only time we use this to allocate a humongous region is "
244 "when we are allocating a single humongous region");
245
246 HeapRegion* res;
247 if (G1StressConcRegionFreeing) {
248 if (!_secondary_free_list.is_empty()) {
249 if (G1ConcRegionFreeingVerbose) {
250 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
251 "forced to look at the secondary_free_list");
252 }
253 res = new_region_try_secondary_free_list(is_old);
254 if (res != NULL) {
255 return res;
256 }
257 }
258 }
259
260 res = _hrm.allocate_free_region(is_old);
261
262 if (res == NULL) {
263 if (G1ConcRegionFreeingVerbose) {
264 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
265 "res == NULL, trying the secondary_free_list");
266 }
267 res = new_region_try_secondary_free_list(is_old);
268 }
269 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
270 // Currently, only attempts to allocate GC alloc regions set
271 // do_expand to true. So, we should only reach here during a
272 // safepoint. If this assumption changes we might have to
273 // reconsider the use of _expand_heap_after_alloc_failure.
274 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
275
276 ergo_verbose1(ErgoHeapSizing,
277 "attempt heap expansion",
278 ergo_format_reason("region allocation request failed")
279 ergo_format_byte("allocation request"),
280 word_size * HeapWordSize);
281 if (expand(word_size * HeapWordSize)) {
282 // Given that expand() succeeded in expanding the heap, and we
283 // always expand the heap by an amount aligned to the heap
284 // region size, the free list should in theory not be empty.
285 // In either case allocate_free_region() will check for NULL.
286 res = _hrm.allocate_free_region(is_old);
287 } else {
288 _expand_heap_after_alloc_failure = false;
289 }
290 }
291 return res;
292 }
293
294 HeapWord*
295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
296 uint num_regions,
297 size_t word_size,
298 AllocationContext_t context) {
299 assert(first != G1_NO_HRM_INDEX, "pre-condition");
300 assert(is_humongous(word_size), "word_size should be humongous");
301 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
302
303 // Index of last region in the series + 1.
304 uint last = first + num_regions;
305
306 // We need to initialize the region(s) we just discovered. This is
307 // a bit tricky given that it can happen concurrently with
308 // refinement threads refining cards on these regions and
309 // potentially wanting to refine the BOT as they are scanning
310 // those cards (this can happen shortly after a cleanup; see CR
311 // 6991377). So we have to set up the region(s) carefully and in
312 // a specific order.
313
314 // The word size sum of all the regions we will allocate.
315 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
316 assert(word_size <= word_size_sum, "sanity");
317
318 // This will be the "starts humongous" region.
319 HeapRegion* first_hr = region_at(first);
320 // The header of the new object will be placed at the bottom of
321 // the first region.
322 HeapWord* new_obj = first_hr->bottom();
323 // This will be the new top of the new object.
324 HeapWord* obj_top = new_obj + word_size;
325
326 // First, we need to zero the header of the space that we will be
327 // allocating. When we update top further down, some refinement
328 // threads might try to scan the region. By zeroing the header we
329 // ensure that any thread that will try to scan the region will
330 // come across the zero klass word and bail out.
331 //
332 // NOTE: It would not have been correct to have used
333 // CollectedHeap::fill_with_object() and make the space look like
334 // an int array. The thread that is doing the allocation will
335 // later update the object header to a potentially different array
336 // type and, for a very short period of time, the klass and length
337 // fields will be inconsistent. This could cause a refinement
338 // thread to calculate the object size incorrectly.
339 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
340
341 // We will set up the first region as "starts humongous". This
342 // will also update the BOT covering all the regions to reflect
343 // that there is a single object that starts at the bottom of the
344 // first region.
345 first_hr->set_starts_humongous(obj_top);
346 first_hr->set_allocation_context(context);
347 // Then, if there are any, we will set up the "continues
348 // humongous" regions.
349 HeapRegion* hr = NULL;
350 for (uint i = first + 1; i < last; ++i) {
351 hr = region_at(i);
352 hr->set_continues_humongous(first_hr);
353 hr->set_allocation_context(context);
354 }
355
356 // Up to this point no concurrent thread would have been able to
357 // do any scanning on any region in this series. All the top
358 // fields still point to bottom, so the intersection between
359 // [bottom,top] and [card_start,card_end] will be empty. Before we
360 // update the top fields, we'll do a storestore to make sure that
361 // no thread sees the update to top before the zeroing of the
362 // object header and the BOT initialization.
363 OrderAccess::storestore();
364
365 // Now that the BOT and the object header have been initialized,
366 // we can update top of the "starts humongous" region.
367 first_hr->set_top(MIN2(first_hr->end(), obj_top));
368 if (_hr_printer.is_active()) {
369 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->end());
370 }
371
372 // Now, we will update the top fields of the "continues humongous"
373 // regions. The reason we need to do this is that, otherwise,
374 // these regions would look empty and this will confuse parts of
375 // G1. For example, the code that looks for a consecutive number
376 // of empty regions will consider them empty and try to
377 // re-allocate them. We can extend is_empty() to also include
378 // !is_continues_humongous(), but it is easier to just update the top
379 // fields here. The way we set top for all regions (i.e., top ==
380 // end for all regions but the last one, top == new_top for the
381 // last one) is actually used when we will free up the humongous
382 // region in free_humongous_region().
383 hr = NULL;
384 for (uint i = first + 1; i < last; ++i) {
385 hr = region_at(i);
386 if ((i + 1) == last) {
387 // last continues humongous region
388 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
389 "new_top should fall on this region");
390 hr->set_top(obj_top);
391 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
392 } else {
393 // not last one
394 assert(obj_top > hr->end(), "obj_top should be above this region");
395 hr->set_top(hr->end());
396 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
397 }
398 }
399 // If we have continues humongous regions (hr != NULL), its top should
400 // match obj_top.
401 assert(hr == NULL || (hr->top() == obj_top), "sanity");
402 check_bitmaps("Humongous Region Allocation", first_hr);
403
404 increase_used(word_size * HeapWordSize);
405
406 for (uint i = first; i < last; ++i) {
407 _humongous_set.add(region_at(i));
408 }
409
410 return new_obj;
411 }
412
413 // If could fit into free regions w/o expansion, try.
414 // Otherwise, if can expand, do so.
415 // Otherwise, if using ex regions might help, try with ex given back.
416 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
417 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
418
419 verify_region_sets_optional();
420
421 uint first = G1_NO_HRM_INDEX;
422 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
423
424 if (obj_regions == 1) {
425 // Only one region to allocate, try to use a fast path by directly allocating
426 // from the free lists. Do not try to expand here, we will potentially do that
427 // later.
428 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
429 if (hr != NULL) {
430 first = hr->hrm_index();
431 }
432 } else {
433 // We can't allocate humongous regions spanning more than one region while
434 // cleanupComplete() is running, since some of the regions we find to be
435 // empty might not yet be added to the free list. It is not straightforward
436 // to know in which list they are on so that we can remove them. We only
437 // need to do this if we need to allocate more than one region to satisfy the
438 // current humongous allocation request. If we are only allocating one region
439 // we use the one-region region allocation code (see above), that already
440 // potentially waits for regions from the secondary free list.
441 wait_while_free_regions_coming();
442 append_secondary_free_list_if_not_empty_with_lock();
443
444 // Policy: Try only empty regions (i.e. already committed first). Maybe we
445 // are lucky enough to find some.
446 first = _hrm.find_contiguous_only_empty(obj_regions);
447 if (first != G1_NO_HRM_INDEX) {
448 _hrm.allocate_free_regions_starting_at(first, obj_regions);
449 }
450 }
451
452 if (first == G1_NO_HRM_INDEX) {
453 // Policy: We could not find enough regions for the humongous object in the
454 // free list. Look through the heap to find a mix of free and uncommitted regions.
455 // If so, try expansion.
456 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
457 if (first != G1_NO_HRM_INDEX) {
458 // We found something. Make sure these regions are committed, i.e. expand
459 // the heap. Alternatively we could do a defragmentation GC.
460 ergo_verbose1(ErgoHeapSizing,
461 "attempt heap expansion",
462 ergo_format_reason("humongous allocation request failed")
463 ergo_format_byte("allocation request"),
464 word_size * HeapWordSize);
465
466 _hrm.expand_at(first, obj_regions);
467 g1_policy()->record_new_heap_size(num_regions());
468
469 #ifdef ASSERT
470 for (uint i = first; i < first + obj_regions; ++i) {
471 HeapRegion* hr = region_at(i);
472 assert(hr->is_free(), "sanity");
473 assert(hr->is_empty(), "sanity");
474 assert(is_on_master_free_list(hr), "sanity");
475 }
476 #endif
477 _hrm.allocate_free_regions_starting_at(first, obj_regions);
478 } else {
479 // Policy: Potentially trigger a defragmentation GC.
480 }
481 }
482
483 HeapWord* result = NULL;
484 if (first != G1_NO_HRM_INDEX) {
485 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
486 word_size, context);
487 assert(result != NULL, "it should always return a valid result");
488
489 // A successful humongous object allocation changes the used space
490 // information of the old generation so we need to recalculate the
491 // sizes and update the jstat counters here.
492 g1mm()->update_sizes();
493 }
494
495 verify_region_sets_optional();
496
497 return result;
498 }
499
500 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
501 assert_heap_not_locked_and_not_at_safepoint();
502 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
503
504 uint dummy_gc_count_before;
505 uint dummy_gclocker_retry_count = 0;
506 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
507 }
508
509 HeapWord*
510 G1CollectedHeap::mem_allocate(size_t word_size,
511 bool* gc_overhead_limit_was_exceeded) {
512 assert_heap_not_locked_and_not_at_safepoint();
513
514 // Loop until the allocation is satisfied, or unsatisfied after GC.
515 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
516 uint gc_count_before;
517
518 HeapWord* result = NULL;
519 if (!is_humongous(word_size)) {
520 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
521 } else {
522 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
523 }
524 if (result != NULL) {
525 return result;
526 }
527
528 // Create the garbage collection operation...
529 VM_G1CollectForAllocation op(gc_count_before, word_size);
530 op.set_allocation_context(AllocationContext::current());
531
532 // ...and get the VM thread to execute it.
533 VMThread::execute(&op);
534
535 if (op.prologue_succeeded() && op.pause_succeeded()) {
536 // If the operation was successful we'll return the result even
537 // if it is NULL. If the allocation attempt failed immediately
538 // after a Full GC, it's unlikely we'll be able to allocate now.
539 HeapWord* result = op.result();
540 if (result != NULL && !is_humongous(word_size)) {
541 // Allocations that take place on VM operations do not do any
542 // card dirtying and we have to do it here. We only have to do
543 // this for non-humongous allocations, though.
544 dirty_young_block(result, word_size);
545 }
546 return result;
547 } else {
548 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
549 return NULL;
550 }
551 assert(op.result() == NULL,
552 "the result should be NULL if the VM op did not succeed");
553 }
554
555 // Give a warning if we seem to be looping forever.
556 if ((QueuedAllocationWarningCount > 0) &&
557 (try_count % QueuedAllocationWarningCount == 0)) {
558 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
559 }
560 }
561
562 ShouldNotReachHere();
563 return NULL;
564 }
565
566 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
567 AllocationContext_t context,
568 uint* gc_count_before_ret,
569 uint* gclocker_retry_count_ret) {
570 // Make sure you read the note in attempt_allocation_humongous().
571
572 assert_heap_not_locked_and_not_at_safepoint();
573 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
574 "be called for humongous allocation requests");
575
576 // We should only get here after the first-level allocation attempt
577 // (attempt_allocation()) failed to allocate.
578
579 // We will loop until a) we manage to successfully perform the
580 // allocation or b) we successfully schedule a collection which
581 // fails to perform the allocation. b) is the only case when we'll
582 // return NULL.
583 HeapWord* result = NULL;
584 for (int try_count = 1; /* we'll return */; try_count += 1) {
585 bool should_try_gc;
586 uint gc_count_before;
587
588 {
589 MutexLockerEx x(Heap_lock);
590 result = _allocator->attempt_allocation_locked(word_size, context);
591 if (result != NULL) {
592 return result;
593 }
594
595 if (GC_locker::is_active_and_needs_gc()) {
596 if (g1_policy()->can_expand_young_list()) {
597 // No need for an ergo verbose message here,
598 // can_expand_young_list() does this when it returns true.
599 result = _allocator->attempt_allocation_force(word_size, context);
600 if (result != NULL) {
601 return result;
602 }
603 }
604 should_try_gc = false;
605 } else {
606 // The GCLocker may not be active but the GCLocker initiated
607 // GC may not yet have been performed (GCLocker::needs_gc()
608 // returns true). In this case we do not try this GC and
609 // wait until the GCLocker initiated GC is performed, and
610 // then retry the allocation.
611 if (GC_locker::needs_gc()) {
612 should_try_gc = false;
613 } else {
614 // Read the GC count while still holding the Heap_lock.
615 gc_count_before = total_collections();
616 should_try_gc = true;
617 }
618 }
619 }
620
621 if (should_try_gc) {
622 bool succeeded;
623 result = do_collection_pause(word_size, gc_count_before, &succeeded,
624 GCCause::_g1_inc_collection_pause);
625 if (result != NULL) {
626 assert(succeeded, "only way to get back a non-NULL result");
627 return result;
628 }
629
630 if (succeeded) {
631 // If we get here we successfully scheduled a collection which
632 // failed to allocate. No point in trying to allocate
633 // further. We'll just return NULL.
634 MutexLockerEx x(Heap_lock);
635 *gc_count_before_ret = total_collections();
636 return NULL;
637 }
638 } else {
639 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
640 MutexLockerEx x(Heap_lock);
641 *gc_count_before_ret = total_collections();
642 return NULL;
643 }
644 // The GCLocker is either active or the GCLocker initiated
645 // GC has not yet been performed. Stall until it is and
646 // then retry the allocation.
647 GC_locker::stall_until_clear();
648 (*gclocker_retry_count_ret) += 1;
649 }
650
651 // We can reach here if we were unsuccessful in scheduling a
652 // collection (because another thread beat us to it) or if we were
653 // stalled due to the GC locker. In either can we should retry the
654 // allocation attempt in case another thread successfully
655 // performed a collection and reclaimed enough space. We do the
656 // first attempt (without holding the Heap_lock) here and the
657 // follow-on attempt will be at the start of the next loop
658 // iteration (after taking the Heap_lock).
659 result = _allocator->attempt_allocation(word_size, context);
660 if (result != NULL) {
661 return result;
662 }
663
664 // Give a warning if we seem to be looping forever.
665 if ((QueuedAllocationWarningCount > 0) &&
666 (try_count % QueuedAllocationWarningCount == 0)) {
667 warning("G1CollectedHeap::attempt_allocation_slow() "
668 "retries %d times", try_count);
669 }
670 }
671
672 ShouldNotReachHere();
673 return NULL;
674 }
675
676 void G1CollectedHeap::begin_archive_alloc_range() {
677 assert_at_safepoint(true /* should_be_vm_thread */);
678 if (_archive_allocator == NULL) {
679 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
680 }
681 }
682
683 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
684 // Allocations in archive regions cannot be of a size that would be considered
685 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
686 // may be different at archive-restore time.
687 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
688 }
689
690 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
691 assert_at_safepoint(true /* should_be_vm_thread */);
692 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
693 if (is_archive_alloc_too_large(word_size)) {
694 return NULL;
695 }
696 return _archive_allocator->archive_mem_allocate(word_size);
697 }
698
699 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
700 size_t end_alignment_in_bytes) {
701 assert_at_safepoint(true /* should_be_vm_thread */);
702 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
703
704 // Call complete_archive to do the real work, filling in the MemRegion
705 // array with the archive regions.
706 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
707 delete _archive_allocator;
708 _archive_allocator = NULL;
709 }
710
711 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
712 assert(ranges != NULL, "MemRegion array NULL");
713 assert(count != 0, "No MemRegions provided");
714 MemRegion reserved = _hrm.reserved();
715 for (size_t i = 0; i < count; i++) {
716 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
717 return false;
718 }
719 }
720 return true;
721 }
722
723 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
724 assert(!is_init_completed(), "Expect to be called at JVM init time");
725 assert(ranges != NULL, "MemRegion array NULL");
726 assert(count != 0, "No MemRegions provided");
727 MutexLockerEx x(Heap_lock);
728
729 MemRegion reserved = _hrm.reserved();
730 HeapWord* prev_last_addr = NULL;
731 HeapRegion* prev_last_region = NULL;
732
733 // Temporarily disable pretouching of heap pages. This interface is used
734 // when mmap'ing archived heap data in, so pre-touching is wasted.
735 FlagSetting fs(AlwaysPreTouch, false);
736
737 // Enable archive object checking in G1MarkSweep. We have to let it know
738 // about each archive range, so that objects in those ranges aren't marked.
739 G1MarkSweep::enable_archive_object_check();
740
741 // For each specified MemRegion range, allocate the corresponding G1
742 // regions and mark them as archive regions. We expect the ranges in
743 // ascending starting address order, without overlap.
744 for (size_t i = 0; i < count; i++) {
745 MemRegion curr_range = ranges[i];
746 HeapWord* start_address = curr_range.start();
747 size_t word_size = curr_range.word_size();
748 HeapWord* last_address = curr_range.last();
749 size_t commits = 0;
750
751 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
752 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
753 p2i(start_address), p2i(last_address));
754 guarantee(start_address > prev_last_addr,
755 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
756 p2i(start_address), p2i(prev_last_addr));
757 prev_last_addr = last_address;
758
759 // Check for ranges that start in the same G1 region in which the previous
760 // range ended, and adjust the start address so we don't try to allocate
761 // the same region again. If the current range is entirely within that
762 // region, skip it, just adjusting the recorded top.
763 HeapRegion* start_region = _hrm.addr_to_region(start_address);
764 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
765 start_address = start_region->end();
766 if (start_address > last_address) {
767 increase_used(word_size * HeapWordSize);
768 start_region->set_top(last_address + 1);
769 continue;
770 }
771 start_region->set_top(start_address);
772 curr_range = MemRegion(start_address, last_address + 1);
773 start_region = _hrm.addr_to_region(start_address);
774 }
775
776 // Perform the actual region allocation, exiting if it fails.
777 // Then note how much new space we have allocated.
778 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
779 return false;
780 }
781 increase_used(word_size * HeapWordSize);
782 if (commits != 0) {
783 ergo_verbose1(ErgoHeapSizing,
784 "attempt heap expansion",
785 ergo_format_reason("allocate archive regions")
786 ergo_format_byte("total size"),
787 HeapRegion::GrainWords * HeapWordSize * commits);
788 }
789
790 // Mark each G1 region touched by the range as archive, add it to the old set,
791 // and set the allocation context and top.
792 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
793 HeapRegion* last_region = _hrm.addr_to_region(last_address);
794 prev_last_region = last_region;
795
796 while (curr_region != NULL) {
797 assert(curr_region->is_empty() && !curr_region->is_pinned(),
798 "Region already in use (index %u)", curr_region->hrm_index());
799 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
800 curr_region->set_allocation_context(AllocationContext::system());
801 curr_region->set_archive();
802 _old_set.add(curr_region);
803 if (curr_region != last_region) {
804 curr_region->set_top(curr_region->end());
805 curr_region = _hrm.next_region_in_heap(curr_region);
806 } else {
807 curr_region->set_top(last_address + 1);
808 curr_region = NULL;
809 }
810 }
811
812 // Notify mark-sweep of the archive range.
813 G1MarkSweep::set_range_archive(curr_range, true);
814 }
815 return true;
816 }
817
818 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
819 assert(!is_init_completed(), "Expect to be called at JVM init time");
820 assert(ranges != NULL, "MemRegion array NULL");
821 assert(count != 0, "No MemRegions provided");
822 MemRegion reserved = _hrm.reserved();
823 HeapWord *prev_last_addr = NULL;
824 HeapRegion* prev_last_region = NULL;
825
826 // For each MemRegion, create filler objects, if needed, in the G1 regions
827 // that contain the address range. The address range actually within the
828 // MemRegion will not be modified. That is assumed to have been initialized
829 // elsewhere, probably via an mmap of archived heap data.
830 MutexLockerEx x(Heap_lock);
831 for (size_t i = 0; i < count; i++) {
832 HeapWord* start_address = ranges[i].start();
833 HeapWord* last_address = ranges[i].last();
834
835 assert(reserved.contains(start_address) && reserved.contains(last_address),
836 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
837 p2i(start_address), p2i(last_address));
838 assert(start_address > prev_last_addr,
839 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
840 p2i(start_address), p2i(prev_last_addr));
841
842 HeapRegion* start_region = _hrm.addr_to_region(start_address);
843 HeapRegion* last_region = _hrm.addr_to_region(last_address);
844 HeapWord* bottom_address = start_region->bottom();
845
846 // Check for a range beginning in the same region in which the
847 // previous one ended.
848 if (start_region == prev_last_region) {
849 bottom_address = prev_last_addr + 1;
850 }
851
852 // Verify that the regions were all marked as archive regions by
853 // alloc_archive_regions.
854 HeapRegion* curr_region = start_region;
855 while (curr_region != NULL) {
856 guarantee(curr_region->is_archive(),
857 "Expected archive region at index %u", curr_region->hrm_index());
858 if (curr_region != last_region) {
859 curr_region = _hrm.next_region_in_heap(curr_region);
860 } else {
861 curr_region = NULL;
862 }
863 }
864
865 prev_last_addr = last_address;
866 prev_last_region = last_region;
867
868 // Fill the memory below the allocated range with dummy object(s),
869 // if the region bottom does not match the range start, or if the previous
870 // range ended within the same G1 region, and there is a gap.
871 if (start_address != bottom_address) {
872 size_t fill_size = pointer_delta(start_address, bottom_address);
873 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
874 increase_used(fill_size * HeapWordSize);
875 }
876 }
877 }
878
879 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
880 uint* gc_count_before_ret,
881 uint* gclocker_retry_count_ret) {
882 assert_heap_not_locked_and_not_at_safepoint();
883 assert(!is_humongous(word_size), "attempt_allocation() should not "
884 "be called for humongous allocation requests");
885
886 AllocationContext_t context = AllocationContext::current();
887 HeapWord* result = _allocator->attempt_allocation(word_size, context);
888
889 if (result == NULL) {
890 result = attempt_allocation_slow(word_size,
891 context,
892 gc_count_before_ret,
893 gclocker_retry_count_ret);
894 }
895 assert_heap_not_locked();
896 if (result != NULL) {
897 dirty_young_block(result, word_size);
898 }
899 return result;
900 }
901
902 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
903 assert(!is_init_completed(), "Expect to be called at JVM init time");
904 assert(ranges != NULL, "MemRegion array NULL");
905 assert(count != 0, "No MemRegions provided");
906 MemRegion reserved = _hrm.reserved();
907 HeapWord* prev_last_addr = NULL;
908 HeapRegion* prev_last_region = NULL;
909 size_t size_used = 0;
910 size_t uncommitted_regions = 0;
911
912 // For each Memregion, free the G1 regions that constitute it, and
913 // notify mark-sweep that the range is no longer to be considered 'archive.'
914 MutexLockerEx x(Heap_lock);
915 for (size_t i = 0; i < count; i++) {
916 HeapWord* start_address = ranges[i].start();
917 HeapWord* last_address = ranges[i].last();
918
919 assert(reserved.contains(start_address) && reserved.contains(last_address),
920 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
921 p2i(start_address), p2i(last_address));
922 assert(start_address > prev_last_addr,
923 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
924 p2i(start_address), p2i(prev_last_addr));
925 size_used += ranges[i].byte_size();
926 prev_last_addr = last_address;
927
928 HeapRegion* start_region = _hrm.addr_to_region(start_address);
929 HeapRegion* last_region = _hrm.addr_to_region(last_address);
930
931 // Check for ranges that start in the same G1 region in which the previous
932 // range ended, and adjust the start address so we don't try to free
933 // the same region again. If the current range is entirely within that
934 // region, skip it.
935 if (start_region == prev_last_region) {
936 start_address = start_region->end();
937 if (start_address > last_address) {
938 continue;
939 }
940 start_region = _hrm.addr_to_region(start_address);
941 }
942 prev_last_region = last_region;
943
944 // After verifying that each region was marked as an archive region by
945 // alloc_archive_regions, set it free and empty and uncommit it.
946 HeapRegion* curr_region = start_region;
947 while (curr_region != NULL) {
948 guarantee(curr_region->is_archive(),
949 "Expected archive region at index %u", curr_region->hrm_index());
950 uint curr_index = curr_region->hrm_index();
951 _old_set.remove(curr_region);
952 curr_region->set_free();
953 curr_region->set_top(curr_region->bottom());
954 if (curr_region != last_region) {
955 curr_region = _hrm.next_region_in_heap(curr_region);
956 } else {
957 curr_region = NULL;
958 }
959 _hrm.shrink_at(curr_index, 1);
960 uncommitted_regions++;
961 }
962
963 // Notify mark-sweep that this is no longer an archive range.
964 G1MarkSweep::set_range_archive(ranges[i], false);
965 }
966
967 if (uncommitted_regions != 0) {
968 ergo_verbose1(ErgoHeapSizing,
969 "attempt heap shrinking",
970 ergo_format_reason("uncommitted archive regions")
971 ergo_format_byte("total size"),
972 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
973 }
974 decrease_used(size_used);
975 }
976
977 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
978 uint* gc_count_before_ret,
979 uint* gclocker_retry_count_ret) {
980 // The structure of this method has a lot of similarities to
981 // attempt_allocation_slow(). The reason these two were not merged
982 // into a single one is that such a method would require several "if
983 // allocation is not humongous do this, otherwise do that"
984 // conditional paths which would obscure its flow. In fact, an early
985 // version of this code did use a unified method which was harder to
986 // follow and, as a result, it had subtle bugs that were hard to
987 // track down. So keeping these two methods separate allows each to
988 // be more readable. It will be good to keep these two in sync as
989 // much as possible.
990
991 assert_heap_not_locked_and_not_at_safepoint();
992 assert(is_humongous(word_size), "attempt_allocation_humongous() "
993 "should only be called for humongous allocations");
994
995 // Humongous objects can exhaust the heap quickly, so we should check if we
996 // need to start a marking cycle at each humongous object allocation. We do
997 // the check before we do the actual allocation. The reason for doing it
998 // before the allocation is that we avoid having to keep track of the newly
999 // allocated memory while we do a GC.
1000 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1001 word_size)) {
1002 collect(GCCause::_g1_humongous_allocation);
1003 }
1004
1005 // We will loop until a) we manage to successfully perform the
1006 // allocation or b) we successfully schedule a collection which
1007 // fails to perform the allocation. b) is the only case when we'll
1008 // return NULL.
1009 HeapWord* result = NULL;
1010 for (int try_count = 1; /* we'll return */; try_count += 1) {
1011 bool should_try_gc;
1012 uint gc_count_before;
1013
1014 {
1015 MutexLockerEx x(Heap_lock);
1016
1017 // Given that humongous objects are not allocated in young
1018 // regions, we'll first try to do the allocation without doing a
1019 // collection hoping that there's enough space in the heap.
1020 result = humongous_obj_allocate(word_size, AllocationContext::current());
1021 if (result != NULL) {
1022 return result;
1023 }
1024
1025 if (GC_locker::is_active_and_needs_gc()) {
1026 should_try_gc = false;
1027 } else {
1028 // The GCLocker may not be active but the GCLocker initiated
1029 // GC may not yet have been performed (GCLocker::needs_gc()
1030 // returns true). In this case we do not try this GC and
1031 // wait until the GCLocker initiated GC is performed, and
1032 // then retry the allocation.
1033 if (GC_locker::needs_gc()) {
1034 should_try_gc = false;
1035 } else {
1036 // Read the GC count while still holding the Heap_lock.
1037 gc_count_before = total_collections();
1038 should_try_gc = true;
1039 }
1040 }
1041 }
1042
1043 if (should_try_gc) {
1044 // If we failed to allocate the humongous object, we should try to
1045 // do a collection pause (if we're allowed) in case it reclaims
1046 // enough space for the allocation to succeed after the pause.
1047
1048 bool succeeded;
1049 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1050 GCCause::_g1_humongous_allocation);
1051 if (result != NULL) {
1052 assert(succeeded, "only way to get back a non-NULL result");
1053 return result;
1054 }
1055
1056 if (succeeded) {
1057 // If we get here we successfully scheduled a collection which
1058 // failed to allocate. No point in trying to allocate
1059 // further. We'll just return NULL.
1060 MutexLockerEx x(Heap_lock);
1061 *gc_count_before_ret = total_collections();
1062 return NULL;
1063 }
1064 } else {
1065 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1066 MutexLockerEx x(Heap_lock);
1067 *gc_count_before_ret = total_collections();
1068 return NULL;
1069 }
1070 // The GCLocker is either active or the GCLocker initiated
1071 // GC has not yet been performed. Stall until it is and
1072 // then retry the allocation.
1073 GC_locker::stall_until_clear();
1074 (*gclocker_retry_count_ret) += 1;
1075 }
1076
1077 // We can reach here if we were unsuccessful in scheduling a
1078 // collection (because another thread beat us to it) or if we were
1079 // stalled due to the GC locker. In either can we should retry the
1080 // allocation attempt in case another thread successfully
1081 // performed a collection and reclaimed enough space. Give a
1082 // warning if we seem to be looping forever.
1083
1084 if ((QueuedAllocationWarningCount > 0) &&
1085 (try_count % QueuedAllocationWarningCount == 0)) {
1086 warning("G1CollectedHeap::attempt_allocation_humongous() "
1087 "retries %d times", try_count);
1088 }
1089 }
1090
1091 ShouldNotReachHere();
1092 return NULL;
1093 }
1094
1095 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1096 AllocationContext_t context,
1097 bool expect_null_mutator_alloc_region) {
1098 assert_at_safepoint(true /* should_be_vm_thread */);
1099 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1100 "the current alloc region was unexpectedly found to be non-NULL");
1101
1102 if (!is_humongous(word_size)) {
1103 return _allocator->attempt_allocation_locked(word_size, context);
1104 } else {
1105 HeapWord* result = humongous_obj_allocate(word_size, context);
1106 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1107 collector_state()->set_initiate_conc_mark_if_possible(true);
1108 }
1109 return result;
1110 }
1111
1112 ShouldNotReachHere();
1113 }
1114
1115 class PostMCRemSetClearClosure: public HeapRegionClosure {
1116 G1CollectedHeap* _g1h;
1117 ModRefBarrierSet* _mr_bs;
1118 public:
1119 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1120 _g1h(g1h), _mr_bs(mr_bs) {}
1121
1122 bool doHeapRegion(HeapRegion* r) {
1123 HeapRegionRemSet* hrrs = r->rem_set();
1124
1125 _g1h->reset_gc_time_stamps(r);
1126
1127 if (r->is_continues_humongous()) {
1128 // We'll assert that the strong code root list and RSet is empty
1129 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1130 assert(hrrs->occupied() == 0, "RSet should be empty");
1131 return false;
1132 }
1133
1134 hrrs->clear();
1135 // You might think here that we could clear just the cards
1136 // corresponding to the used region. But no: if we leave a dirty card
1137 // in a region we might allocate into, then it would prevent that card
1138 // from being enqueued, and cause it to be missed.
1139 // Re: the performance cost: we shouldn't be doing full GC anyway!
1140 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1141
1142 return false;
1143 }
1144 };
1145
1146 void G1CollectedHeap::clear_rsets_post_compaction() {
1147 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1148 heap_region_iterate(&rs_clear);
1149 }
1150
1151 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1152 G1CollectedHeap* _g1h;
1153 UpdateRSOopClosure _cl;
1154 public:
1155 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1156 _cl(g1->g1_rem_set(), worker_i),
1157 _g1h(g1)
1158 { }
1159
1160 bool doHeapRegion(HeapRegion* r) {
1161 if (!r->is_continues_humongous()) {
1162 _cl.set_from(r);
1163 r->oop_iterate(&_cl);
1164 }
1165 return false;
1166 }
1167 };
1168
1169 class ParRebuildRSTask: public AbstractGangTask {
1170 G1CollectedHeap* _g1;
1171 HeapRegionClaimer _hrclaimer;
1172
1173 public:
1174 ParRebuildRSTask(G1CollectedHeap* g1) :
1175 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1176
1177 void work(uint worker_id) {
1178 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1179 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1180 }
1181 };
1182
1183 class PostCompactionPrinterClosure: public HeapRegionClosure {
1184 private:
1185 G1HRPrinter* _hr_printer;
1186 public:
1187 bool doHeapRegion(HeapRegion* hr) {
1188 assert(!hr->is_young(), "not expecting to find young regions");
1189 if (hr->is_free()) {
1190 // We only generate output for non-empty regions.
1191 } else if (hr->is_starts_humongous()) {
1192 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1193 } else if (hr->is_continues_humongous()) {
1194 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1195 } else if (hr->is_archive()) {
1196 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1197 } else if (hr->is_old()) {
1198 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1199 } else {
1200 ShouldNotReachHere();
1201 }
1202 return false;
1203 }
1204
1205 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1206 : _hr_printer(hr_printer) { }
1207 };
1208
1209 void G1CollectedHeap::print_hrm_post_compaction() {
1210 PostCompactionPrinterClosure cl(hr_printer());
1211 heap_region_iterate(&cl);
1212 }
1213
1214 bool G1CollectedHeap::do_collection(bool explicit_gc,
1215 bool clear_all_soft_refs,
1216 size_t word_size) {
1217 assert_at_safepoint(true /* should_be_vm_thread */);
1218
1219 if (GC_locker::check_active_before_gc()) {
1220 return false;
1221 }
1222
1223 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1224 gc_timer->register_gc_start();
1225
1226 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1227 GCIdMark gc_id_mark;
1228 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1229
1230 SvcGCMarker sgcm(SvcGCMarker::FULL);
1231 ResourceMark rm;
1232
1233 G1Log::update_level();
1234 print_heap_before_gc();
1235 trace_heap_before_gc(gc_tracer);
1236
1237 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1238
1239 verify_region_sets_optional();
1240
1241 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1242 collector_policy()->should_clear_all_soft_refs();
1243
1244 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1245
1246 {
1247 IsGCActiveMark x;
1248
1249 // Timing
1250 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1251 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1252
1253 {
1254 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1255 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1256 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1257
1258 g1_policy()->record_full_collection_start();
1259
1260 // Note: When we have a more flexible GC logging framework that
1261 // allows us to add optional attributes to a GC log record we
1262 // could consider timing and reporting how long we wait in the
1263 // following two methods.
1264 wait_while_free_regions_coming();
1265 // If we start the compaction before the CM threads finish
1266 // scanning the root regions we might trip them over as we'll
1267 // be moving objects / updating references. So let's wait until
1268 // they are done. By telling them to abort, they should complete
1269 // early.
1270 _cm->root_regions()->abort();
1271 _cm->root_regions()->wait_until_scan_finished();
1272 append_secondary_free_list_if_not_empty_with_lock();
1273
1274 gc_prologue(true);
1275 increment_total_collections(true /* full gc */);
1276 increment_old_marking_cycles_started();
1277
1278 assert(used() == recalculate_used(), "Should be equal");
1279
1280 verify_before_gc();
1281
1282 check_bitmaps("Full GC Start");
1283 pre_full_gc_dump(gc_timer);
1284
1285 #if defined(COMPILER2) || INCLUDE_JVMCI
1286 DerivedPointerTable::clear();
1287 #endif
1288
1289 // Disable discovery and empty the discovered lists
1290 // for the CM ref processor.
1291 ref_processor_cm()->disable_discovery();
1292 ref_processor_cm()->abandon_partial_discovery();
1293 ref_processor_cm()->verify_no_references_recorded();
1294
1295 // Abandon current iterations of concurrent marking and concurrent
1296 // refinement, if any are in progress. We have to do this before
1297 // wait_until_scan_finished() below.
1298 concurrent_mark()->abort();
1299
1300 // Make sure we'll choose a new allocation region afterwards.
1301 _allocator->release_mutator_alloc_region();
1302 _allocator->abandon_gc_alloc_regions();
1303 g1_rem_set()->cleanupHRRS();
1304
1305 // We should call this after we retire any currently active alloc
1306 // regions so that all the ALLOC / RETIRE events are generated
1307 // before the start GC event.
1308 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1309
1310 // We may have added regions to the current incremental collection
1311 // set between the last GC or pause and now. We need to clear the
1312 // incremental collection set and then start rebuilding it afresh
1313 // after this full GC.
1314 abandon_collection_set(g1_policy()->inc_cset_head());
1315 g1_policy()->clear_incremental_cset();
1316 g1_policy()->stop_incremental_cset_building();
1317
1318 tear_down_region_sets(false /* free_list_only */);
1319 collector_state()->set_gcs_are_young(true);
1320
1321 // See the comments in g1CollectedHeap.hpp and
1322 // G1CollectedHeap::ref_processing_init() about
1323 // how reference processing currently works in G1.
1324
1325 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1326 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1327
1328 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1329 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1330
1331 ref_processor_stw()->enable_discovery();
1332 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1333
1334 // Do collection work
1335 {
1336 HandleMark hm; // Discard invalid handles created during gc
1337 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1338 }
1339
1340 assert(num_free_regions() == 0, "we should not have added any free regions");
1341 rebuild_region_sets(false /* free_list_only */);
1342
1343 // Enqueue any discovered reference objects that have
1344 // not been removed from the discovered lists.
1345 ref_processor_stw()->enqueue_discovered_references();
1346
1347 #if defined(COMPILER2) || INCLUDE_JVMCI
1348 DerivedPointerTable::update_pointers();
1349 #endif
1350
1351 MemoryService::track_memory_usage();
1352
1353 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1354 ref_processor_stw()->verify_no_references_recorded();
1355
1356 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1357 ClassLoaderDataGraph::purge();
1358 MetaspaceAux::verify_metrics();
1359
1360 // Note: since we've just done a full GC, concurrent
1361 // marking is no longer active. Therefore we need not
1362 // re-enable reference discovery for the CM ref processor.
1363 // That will be done at the start of the next marking cycle.
1364 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1365 ref_processor_cm()->verify_no_references_recorded();
1366
1367 reset_gc_time_stamp();
1368 // Since everything potentially moved, we will clear all remembered
1369 // sets, and clear all cards. Later we will rebuild remembered
1370 // sets. We will also reset the GC time stamps of the regions.
1371 clear_rsets_post_compaction();
1372 check_gc_time_stamps();
1373
1374 // Resize the heap if necessary.
1375 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1376
1377 if (_hr_printer.is_active()) {
1378 // We should do this after we potentially resize the heap so
1379 // that all the COMMIT / UNCOMMIT events are generated before
1380 // the end GC event.
1381
1382 print_hrm_post_compaction();
1383 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1384 }
1385
1386 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1387 if (hot_card_cache->use_cache()) {
1388 hot_card_cache->reset_card_counts();
1389 hot_card_cache->reset_hot_cache();
1390 }
1391
1392 // Rebuild remembered sets of all regions.
1393 uint n_workers =
1394 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1395 workers()->active_workers(),
1396 Threads::number_of_non_daemon_threads());
1397 workers()->set_active_workers(n_workers);
1398
1399 ParRebuildRSTask rebuild_rs_task(this);
1400 workers()->run_task(&rebuild_rs_task);
1401
1402 // Rebuild the strong code root lists for each region
1403 rebuild_strong_code_roots();
1404
1405 if (true) { // FIXME
1406 MetaspaceGC::compute_new_size();
1407 }
1408
1409 #ifdef TRACESPINNING
1410 ParallelTaskTerminator::print_termination_counts();
1411 #endif
1412
1413 // Discard all rset updates
1414 JavaThread::dirty_card_queue_set().abandon_logs();
1415 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1416
1417 _young_list->reset_sampled_info();
1418 // At this point there should be no regions in the
1419 // entire heap tagged as young.
1420 assert(check_young_list_empty(true /* check_heap */),
1421 "young list should be empty at this point");
1422
1423 // Update the number of full collections that have been completed.
1424 increment_old_marking_cycles_completed(false /* concurrent */);
1425
1426 _hrm.verify_optional();
1427 verify_region_sets_optional();
1428
1429 verify_after_gc();
1430
1431 // Clear the previous marking bitmap, if needed for bitmap verification.
1432 // Note we cannot do this when we clear the next marking bitmap in
1433 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1434 // objects marked during a full GC against the previous bitmap.
1435 // But we need to clear it before calling check_bitmaps below since
1436 // the full GC has compacted objects and updated TAMS but not updated
1437 // the prev bitmap.
1438 if (G1VerifyBitmaps) {
1439 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1440 }
1441 check_bitmaps("Full GC End");
1442
1443 // Start a new incremental collection set for the next pause
1444 assert(g1_policy()->collection_set() == NULL, "must be");
1445 g1_policy()->start_incremental_cset_building();
1446
1447 clear_cset_fast_test();
1448
1449 _allocator->init_mutator_alloc_region();
1450
1451 g1_policy()->record_full_collection_end();
1452
1453 if (G1Log::fine()) {
1454 g1_policy()->print_heap_transition();
1455 }
1456
1457 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1458 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1459 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1460 // before any GC notifications are raised.
1461 g1mm()->update_sizes();
1462
1463 gc_epilogue(true);
1464 }
1465
1466 if (G1Log::finer()) {
1467 g1_policy()->print_detailed_heap_transition(true /* full */);
1468 }
1469
1470 print_heap_after_gc();
1471 trace_heap_after_gc(gc_tracer);
1472
1473 post_full_gc_dump(gc_timer);
1474
1475 gc_timer->register_gc_end();
1476 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1477 }
1478
1479 return true;
1480 }
1481
1482 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1483 // do_collection() will return whether it succeeded in performing
1484 // the GC. Currently, there is no facility on the
1485 // do_full_collection() API to notify the caller than the collection
1486 // did not succeed (e.g., because it was locked out by the GC
1487 // locker). So, right now, we'll ignore the return value.
1488 bool dummy = do_collection(true, /* explicit_gc */
1489 clear_all_soft_refs,
1490 0 /* word_size */);
1491 }
1492
1493 // This code is mostly copied from TenuredGeneration.
1494 void
1495 G1CollectedHeap::
1496 resize_if_necessary_after_full_collection(size_t word_size) {
1497 // Include the current allocation, if any, and bytes that will be
1498 // pre-allocated to support collections, as "used".
1499 const size_t used_after_gc = used();
1500 const size_t capacity_after_gc = capacity();
1501 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1502
1503 // This is enforced in arguments.cpp.
1504 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1505 "otherwise the code below doesn't make sense");
1506
1507 // We don't have floating point command-line arguments
1508 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1509 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1510 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1511 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1512
1513 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1514 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1515
1516 // We have to be careful here as these two calculations can overflow
1517 // 32-bit size_t's.
1518 double used_after_gc_d = (double) used_after_gc;
1519 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1520 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1521
1522 // Let's make sure that they are both under the max heap size, which
1523 // by default will make them fit into a size_t.
1524 double desired_capacity_upper_bound = (double) max_heap_size;
1525 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1526 desired_capacity_upper_bound);
1527 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1528 desired_capacity_upper_bound);
1529
1530 // We can now safely turn them into size_t's.
1531 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1532 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1533
1534 // This assert only makes sense here, before we adjust them
1535 // with respect to the min and max heap size.
1536 assert(minimum_desired_capacity <= maximum_desired_capacity,
1537 "minimum_desired_capacity = " SIZE_FORMAT ", "
1538 "maximum_desired_capacity = " SIZE_FORMAT,
1539 minimum_desired_capacity, maximum_desired_capacity);
1540
1541 // Should not be greater than the heap max size. No need to adjust
1542 // it with respect to the heap min size as it's a lower bound (i.e.,
1543 // we'll try to make the capacity larger than it, not smaller).
1544 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1545 // Should not be less than the heap min size. No need to adjust it
1546 // with respect to the heap max size as it's an upper bound (i.e.,
1547 // we'll try to make the capacity smaller than it, not greater).
1548 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1549
1550 if (capacity_after_gc < minimum_desired_capacity) {
1551 // Don't expand unless it's significant
1552 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1553 ergo_verbose4(ErgoHeapSizing,
1554 "attempt heap expansion",
1555 ergo_format_reason("capacity lower than "
1556 "min desired capacity after Full GC")
1557 ergo_format_byte("capacity")
1558 ergo_format_byte("occupancy")
1559 ergo_format_byte_perc("min desired capacity"),
1560 capacity_after_gc, used_after_gc,
1561 minimum_desired_capacity, (double) MinHeapFreeRatio);
1562 expand(expand_bytes);
1563
1564 // No expansion, now see if we want to shrink
1565 } else if (capacity_after_gc > maximum_desired_capacity) {
1566 // Capacity too large, compute shrinking size
1567 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1568 ergo_verbose4(ErgoHeapSizing,
1569 "attempt heap shrinking",
1570 ergo_format_reason("capacity higher than "
1571 "max desired capacity after Full GC")
1572 ergo_format_byte("capacity")
1573 ergo_format_byte("occupancy")
1574 ergo_format_byte_perc("max desired capacity"),
1575 capacity_after_gc, used_after_gc,
1576 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1577 shrink(shrink_bytes);
1578 }
1579 }
1580
1581 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1582 AllocationContext_t context,
1583 bool do_gc,
1584 bool clear_all_soft_refs,
1585 bool expect_null_mutator_alloc_region,
1586 bool* gc_succeeded) {
1587 *gc_succeeded = true;
1588 // Let's attempt the allocation first.
1589 HeapWord* result =
1590 attempt_allocation_at_safepoint(word_size,
1591 context,
1592 expect_null_mutator_alloc_region);
1593 if (result != NULL) {
1594 assert(*gc_succeeded, "sanity");
1595 return result;
1596 }
1597
1598 // In a G1 heap, we're supposed to keep allocation from failing by
1599 // incremental pauses. Therefore, at least for now, we'll favor
1600 // expansion over collection. (This might change in the future if we can
1601 // do something smarter than full collection to satisfy a failed alloc.)
1602 result = expand_and_allocate(word_size, context);
1603 if (result != NULL) {
1604 assert(*gc_succeeded, "sanity");
1605 return result;
1606 }
1607
1608 if (do_gc) {
1609 // Expansion didn't work, we'll try to do a Full GC.
1610 *gc_succeeded = do_collection(false, /* explicit_gc */
1611 clear_all_soft_refs,
1612 word_size);
1613 }
1614
1615 return NULL;
1616 }
1617
1618 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1619 AllocationContext_t context,
1620 bool* succeeded) {
1621 assert_at_safepoint(true /* should_be_vm_thread */);
1622
1623 // Attempts to allocate followed by Full GC.
1624 HeapWord* result =
1625 satisfy_failed_allocation_helper(word_size,
1626 context,
1627 true, /* do_gc */
1628 false, /* clear_all_soft_refs */
1629 false, /* expect_null_mutator_alloc_region */
1630 succeeded);
1631
1632 if (result != NULL || !*succeeded) {
1633 return result;
1634 }
1635
1636 // Attempts to allocate followed by Full GC that will collect all soft references.
1637 result = satisfy_failed_allocation_helper(word_size,
1638 context,
1639 true, /* do_gc */
1640 true, /* clear_all_soft_refs */
1641 true, /* expect_null_mutator_alloc_region */
1642 succeeded);
1643
1644 if (result != NULL || !*succeeded) {
1645 return result;
1646 }
1647
1648 // Attempts to allocate, no GC
1649 result = satisfy_failed_allocation_helper(word_size,
1650 context,
1651 false, /* do_gc */
1652 false, /* clear_all_soft_refs */
1653 true, /* expect_null_mutator_alloc_region */
1654 succeeded);
1655
1656 if (result != NULL) {
1657 assert(*succeeded, "sanity");
1658 return result;
1659 }
1660
1661 assert(!collector_policy()->should_clear_all_soft_refs(),
1662 "Flag should have been handled and cleared prior to this point");
1663
1664 // What else? We might try synchronous finalization later. If the total
1665 // space available is large enough for the allocation, then a more
1666 // complete compaction phase than we've tried so far might be
1667 // appropriate.
1668 assert(*succeeded, "sanity");
1669 return NULL;
1670 }
1671
1672 // Attempting to expand the heap sufficiently
1673 // to support an allocation of the given "word_size". If
1674 // successful, perform the allocation and return the address of the
1675 // allocated block, or else "NULL".
1676
1677 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1678 assert_at_safepoint(true /* should_be_vm_thread */);
1679
1680 verify_region_sets_optional();
1681
1682 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1683 ergo_verbose1(ErgoHeapSizing,
1684 "attempt heap expansion",
1685 ergo_format_reason("allocation request failed")
1686 ergo_format_byte("allocation request"),
1687 word_size * HeapWordSize);
1688 if (expand(expand_bytes)) {
1689 _hrm.verify_optional();
1690 verify_region_sets_optional();
1691 return attempt_allocation_at_safepoint(word_size,
1692 context,
1693 false /* expect_null_mutator_alloc_region */);
1694 }
1695 return NULL;
1696 }
1697
1698 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1699 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1700 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1701 HeapRegion::GrainBytes);
1702 ergo_verbose2(ErgoHeapSizing,
1703 "expand the heap",
1704 ergo_format_byte("requested expansion amount")
1705 ergo_format_byte("attempted expansion amount"),
1706 expand_bytes, aligned_expand_bytes);
1707
1708 if (is_maximal_no_gc()) {
1709 ergo_verbose0(ErgoHeapSizing,
1710 "did not expand the heap",
1711 ergo_format_reason("heap already fully expanded"));
1712 return false;
1713 }
1714
1715 double expand_heap_start_time_sec = os::elapsedTime();
1716 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1717 assert(regions_to_expand > 0, "Must expand by at least one region");
1718
1719 uint expanded_by = _hrm.expand_by(regions_to_expand);
1720 if (expand_time_ms != NULL) {
1721 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1722 }
1723
1724 if (expanded_by > 0) {
1725 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1726 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1727 g1_policy()->record_new_heap_size(num_regions());
1728 } else {
1729 ergo_verbose0(ErgoHeapSizing,
1730 "did not expand the heap",
1731 ergo_format_reason("heap expansion operation failed"));
1732 // The expansion of the virtual storage space was unsuccessful.
1733 // Let's see if it was because we ran out of swap.
1734 if (G1ExitOnExpansionFailure &&
1735 _hrm.available() >= regions_to_expand) {
1736 // We had head room...
1737 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1738 }
1739 }
1740 return regions_to_expand > 0;
1741 }
1742
1743 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1744 size_t aligned_shrink_bytes =
1745 ReservedSpace::page_align_size_down(shrink_bytes);
1746 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1747 HeapRegion::GrainBytes);
1748 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1749
1750 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1751 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1752
1753 ergo_verbose3(ErgoHeapSizing,
1754 "shrink the heap",
1755 ergo_format_byte("requested shrinking amount")
1756 ergo_format_byte("aligned shrinking amount")
1757 ergo_format_byte("attempted shrinking amount"),
1758 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1759 if (num_regions_removed > 0) {
1760 g1_policy()->record_new_heap_size(num_regions());
1761 } else {
1762 ergo_verbose0(ErgoHeapSizing,
1763 "did not shrink the heap",
1764 ergo_format_reason("heap shrinking operation failed"));
1765 }
1766 }
1767
1768 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1769 verify_region_sets_optional();
1770
1771 // We should only reach here at the end of a Full GC which means we
1772 // should not not be holding to any GC alloc regions. The method
1773 // below will make sure of that and do any remaining clean up.
1774 _allocator->abandon_gc_alloc_regions();
1775
1776 // Instead of tearing down / rebuilding the free lists here, we
1777 // could instead use the remove_all_pending() method on free_list to
1778 // remove only the ones that we need to remove.
1779 tear_down_region_sets(true /* free_list_only */);
1780 shrink_helper(shrink_bytes);
1781 rebuild_region_sets(true /* free_list_only */);
1782
1783 _hrm.verify_optional();
1784 verify_region_sets_optional();
1785 }
1786
1787 // Public methods.
1788
1789 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1790 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1791 #endif // _MSC_VER
1792
1793
1794 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1795 CollectedHeap(),
1796 _g1_policy(policy_),
1797 _dirty_card_queue_set(false),
1798 _into_cset_dirty_card_queue_set(false),
1799 _is_alive_closure_cm(this),
1800 _is_alive_closure_stw(this),
1801 _ref_processor_cm(NULL),
1802 _ref_processor_stw(NULL),
1803 _bot_shared(NULL),
1804 _cg1r(NULL),
1805 _g1mm(NULL),
1806 _refine_cte_cl(NULL),
1807 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1808 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1809 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1810 _humongous_reclaim_candidates(),
1811 _has_humongous_reclaim_candidates(false),
1812 _archive_allocator(NULL),
1813 _free_regions_coming(false),
1814 _young_list(new YoungList(this)),
1815 _gc_time_stamp(0),
1816 _summary_bytes_used(0),
1817 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1818 _old_evac_stats(OldPLABSize, PLABWeight),
1819 _expand_heap_after_alloc_failure(true),
1820 _old_marking_cycles_started(0),
1821 _old_marking_cycles_completed(0),
1822 _heap_summary_sent(false),
1823 _in_cset_fast_test(),
1824 _dirty_cards_region_list(NULL),
1825 _worker_cset_start_region(NULL),
1826 _worker_cset_start_region_time_stamp(NULL),
1827 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1828 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1829 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1830 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1831
1832 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1833 /* are_GC_task_threads */true,
1834 /* are_ConcurrentGC_threads */false);
1835 _workers->initialize_workers();
1836
1837 _allocator = G1Allocator::create_allocator(this);
1838 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1839
1840 // Override the default _filler_array_max_size so that no humongous filler
1841 // objects are created.
1842 _filler_array_max_size = _humongous_object_threshold_in_words;
1843
1844 uint n_queues = ParallelGCThreads;
1845 _task_queues = new RefToScanQueueSet(n_queues);
1846
1847 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1848 assert(n_rem_sets > 0, "Invariant.");
1849
1850 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1851 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1852 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1853
1854 for (uint i = 0; i < n_queues; i++) {
1855 RefToScanQueue* q = new RefToScanQueue();
1856 q->initialize();
1857 _task_queues->register_queue(i, q);
1858 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1859 }
1860 clear_cset_start_regions();
1861
1862 // Initialize the G1EvacuationFailureALot counters and flags.
1863 NOT_PRODUCT(reset_evacuation_should_fail();)
1864
1865 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1866 }
1867
1868 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1869 size_t size,
1870 size_t translation_factor) {
1871 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1872 // Allocate a new reserved space, preferring to use large pages.
1873 ReservedSpace rs(size, preferred_page_size);
1874 G1RegionToSpaceMapper* result =
1875 G1RegionToSpaceMapper::create_mapper(rs,
1876 size,
1877 rs.alignment(),
1878 HeapRegion::GrainBytes,
1879 translation_factor,
1880 mtGC);
1881 if (TracePageSizes) {
1882 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1883 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1884 }
1885 return result;
1886 }
1887
1888 jint G1CollectedHeap::initialize() {
1889 CollectedHeap::pre_initialize();
1890 os::enable_vtime();
1891
1892 G1Log::init();
1893
1894 // Necessary to satisfy locking discipline assertions.
1895
1896 MutexLocker x(Heap_lock);
1897
1898 // We have to initialize the printer before committing the heap, as
1899 // it will be used then.
1900 _hr_printer.set_active(G1PrintHeapRegions);
1901
1902 // While there are no constraints in the GC code that HeapWordSize
1903 // be any particular value, there are multiple other areas in the
1904 // system which believe this to be true (e.g. oop->object_size in some
1905 // cases incorrectly returns the size in wordSize units rather than
1906 // HeapWordSize).
1907 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1908
1909 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1910 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1911 size_t heap_alignment = collector_policy()->heap_alignment();
1912
1913 // Ensure that the sizes are properly aligned.
1914 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1915 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1916 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1917
1918 _refine_cte_cl = new RefineCardTableEntryClosure();
1919
1920 jint ecode = JNI_OK;
1921 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1922 if (_cg1r == NULL) {
1923 return ecode;
1924 }
1925
1926 // Reserve the maximum.
1927
1928 // When compressed oops are enabled, the preferred heap base
1929 // is calculated by subtracting the requested size from the
1930 // 32Gb boundary and using the result as the base address for
1931 // heap reservation. If the requested size is not aligned to
1932 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1933 // into the ReservedHeapSpace constructor) then the actual
1934 // base of the reserved heap may end up differing from the
1935 // address that was requested (i.e. the preferred heap base).
1936 // If this happens then we could end up using a non-optimal
1937 // compressed oops mode.
1938
1939 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1940 heap_alignment);
1941
1942 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1943
1944 // Create the barrier set for the entire reserved region.
1945 G1SATBCardTableLoggingModRefBS* bs
1946 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1947 bs->initialize();
1948 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1949 set_barrier_set(bs);
1950
1951 // Also create a G1 rem set.
1952 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1953
1954 // Carve out the G1 part of the heap.
1955
1956 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1957 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1958 G1RegionToSpaceMapper* heap_storage =
1959 G1RegionToSpaceMapper::create_mapper(g1_rs,
1960 g1_rs.size(),
1961 page_size,
1962 HeapRegion::GrainBytes,
1963 1,
1964 mtJavaHeap);
1965 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1966 max_byte_size, page_size,
1967 heap_rs.base(),
1968 heap_rs.size());
1969 heap_storage->set_mapping_changed_listener(&_listener);
1970
1971 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1972 G1RegionToSpaceMapper* bot_storage =
1973 create_aux_memory_mapper("Block offset table",
1974 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1975 G1BlockOffsetSharedArray::heap_map_factor());
1976
1977 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1978 G1RegionToSpaceMapper* cardtable_storage =
1979 create_aux_memory_mapper("Card table",
1980 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1981 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1982
1983 G1RegionToSpaceMapper* card_counts_storage =
1984 create_aux_memory_mapper("Card counts table",
1985 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1986 G1CardCounts::heap_map_factor());
1987
1988 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1989 G1RegionToSpaceMapper* prev_bitmap_storage =
1990 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1991 G1RegionToSpaceMapper* next_bitmap_storage =
1992 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1993
1994 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1995 g1_barrier_set()->initialize(cardtable_storage);
1996 // Do later initialization work for concurrent refinement.
1997 _cg1r->init(card_counts_storage);
1998
1999 // 6843694 - ensure that the maximum region index can fit
2000 // in the remembered set structures.
2001 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2002 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2003
2004 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2005 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2006 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2007 "too many cards per region");
2008
2009 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2010
2011 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2012
2013 {
2014 HeapWord* start = _hrm.reserved().start();
2015 HeapWord* end = _hrm.reserved().end();
2016 size_t granularity = HeapRegion::GrainBytes;
2017
2018 _in_cset_fast_test.initialize(start, end, granularity);
2019 _humongous_reclaim_candidates.initialize(start, end, granularity);
2020 }
2021
2022 // Create the ConcurrentMark data structure and thread.
2023 // (Must do this late, so that "max_regions" is defined.)
2024 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2025 if (_cm == NULL || !_cm->completed_initialization()) {
2026 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2027 return JNI_ENOMEM;
2028 }
2029 _cmThread = _cm->cmThread();
2030
2031 // Initialize the from_card cache structure of HeapRegionRemSet.
2032 HeapRegionRemSet::init_heap(max_regions());
2033
2034 // Now expand into the initial heap size.
2035 if (!expand(init_byte_size)) {
2036 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2037 return JNI_ENOMEM;
2038 }
2039
2040 // Perform any initialization actions delegated to the policy.
2041 g1_policy()->init();
2042
2043 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2044 SATB_Q_FL_lock,
2045 G1SATBProcessCompletedThreshold,
2046 Shared_SATB_Q_lock);
2047
2048 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2049 DirtyCardQ_CBL_mon,
2050 DirtyCardQ_FL_lock,
2051 concurrent_g1_refine()->yellow_zone(),
2052 concurrent_g1_refine()->red_zone(),
2053 Shared_DirtyCardQ_lock);
2054
2055 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2056 DirtyCardQ_CBL_mon,
2057 DirtyCardQ_FL_lock,
2058 -1, // never trigger processing
2059 -1, // no limit on length
2060 Shared_DirtyCardQ_lock,
2061 &JavaThread::dirty_card_queue_set());
2062
2063 // Initialize the card queue set used to hold cards containing
2064 // references into the collection set.
2065 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2066 DirtyCardQ_CBL_mon,
2067 DirtyCardQ_FL_lock,
2068 -1, // never trigger processing
2069 -1, // no limit on length
2070 Shared_DirtyCardQ_lock,
2071 &JavaThread::dirty_card_queue_set());
2072
2073 // Here we allocate the dummy HeapRegion that is required by the
2074 // G1AllocRegion class.
2075 HeapRegion* dummy_region = _hrm.get_dummy_region();
2076
2077 // We'll re-use the same region whether the alloc region will
2078 // require BOT updates or not and, if it doesn't, then a non-young
2079 // region will complain that it cannot support allocations without
2080 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2081 dummy_region->set_eden();
2082 // Make sure it's full.
2083 dummy_region->set_top(dummy_region->end());
2084 G1AllocRegion::setup(this, dummy_region);
2085
2086 _allocator->init_mutator_alloc_region();
2087
2088 // Do create of the monitoring and management support so that
2089 // values in the heap have been properly initialized.
2090 _g1mm = new G1MonitoringSupport(this);
2091
2092 G1StringDedup::initialize();
2093
2094 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2095 for (uint i = 0; i < ParallelGCThreads; i++) {
2096 new (&_preserved_objs[i]) OopAndMarkOopStack();
2097 }
2098
2099 return JNI_OK;
2100 }
2101
2102 void G1CollectedHeap::stop() {
2103 // Stop all concurrent threads. We do this to make sure these threads
2104 // do not continue to execute and access resources (e.g. gclog_or_tty)
2105 // that are destroyed during shutdown.
2106 _cg1r->stop();
2107 _cmThread->stop();
2108 if (G1StringDedup::is_enabled()) {
2109 G1StringDedup::stop();
2110 }
2111 }
2112
2113 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2114 return HeapRegion::max_region_size();
2115 }
2116
2117 void G1CollectedHeap::post_initialize() {
2118 CollectedHeap::post_initialize();
2119 ref_processing_init();
2120 }
2121
2122 void G1CollectedHeap::ref_processing_init() {
2123 // Reference processing in G1 currently works as follows:
2124 //
2125 // * There are two reference processor instances. One is
2126 // used to record and process discovered references
2127 // during concurrent marking; the other is used to
2128 // record and process references during STW pauses
2129 // (both full and incremental).
2130 // * Both ref processors need to 'span' the entire heap as
2131 // the regions in the collection set may be dotted around.
2132 //
2133 // * For the concurrent marking ref processor:
2134 // * Reference discovery is enabled at initial marking.
2135 // * Reference discovery is disabled and the discovered
2136 // references processed etc during remarking.
2137 // * Reference discovery is MT (see below).
2138 // * Reference discovery requires a barrier (see below).
2139 // * Reference processing may or may not be MT
2140 // (depending on the value of ParallelRefProcEnabled
2141 // and ParallelGCThreads).
2142 // * A full GC disables reference discovery by the CM
2143 // ref processor and abandons any entries on it's
2144 // discovered lists.
2145 //
2146 // * For the STW processor:
2147 // * Non MT discovery is enabled at the start of a full GC.
2148 // * Processing and enqueueing during a full GC is non-MT.
2149 // * During a full GC, references are processed after marking.
2150 //
2151 // * Discovery (may or may not be MT) is enabled at the start
2152 // of an incremental evacuation pause.
2153 // * References are processed near the end of a STW evacuation pause.
2154 // * For both types of GC:
2155 // * Discovery is atomic - i.e. not concurrent.
2156 // * Reference discovery will not need a barrier.
2157
2158 MemRegion mr = reserved_region();
2159
2160 // Concurrent Mark ref processor
2161 _ref_processor_cm =
2162 new ReferenceProcessor(mr, // span
2163 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2164 // mt processing
2165 ParallelGCThreads,
2166 // degree of mt processing
2167 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2168 // mt discovery
2169 MAX2(ParallelGCThreads, ConcGCThreads),
2170 // degree of mt discovery
2171 false,
2172 // Reference discovery is not atomic
2173 &_is_alive_closure_cm);
2174 // is alive closure
2175 // (for efficiency/performance)
2176
2177 // STW ref processor
2178 _ref_processor_stw =
2179 new ReferenceProcessor(mr, // span
2180 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2181 // mt processing
2182 ParallelGCThreads,
2183 // degree of mt processing
2184 (ParallelGCThreads > 1),
2185 // mt discovery
2186 ParallelGCThreads,
2187 // degree of mt discovery
2188 true,
2189 // Reference discovery is atomic
2190 &_is_alive_closure_stw);
2191 // is alive closure
2192 // (for efficiency/performance)
2193 }
2194
2195 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2196 return g1_policy();
2197 }
2198
2199 size_t G1CollectedHeap::capacity() const {
2200 return _hrm.length() * HeapRegion::GrainBytes;
2201 }
2202
2203 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2204 hr->reset_gc_time_stamp();
2205 }
2206
2207 #ifndef PRODUCT
2208
2209 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2210 private:
2211 unsigned _gc_time_stamp;
2212 bool _failures;
2213
2214 public:
2215 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2216 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2217
2218 virtual bool doHeapRegion(HeapRegion* hr) {
2219 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2220 if (_gc_time_stamp != region_gc_time_stamp) {
2221 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2222 "expected %d", HR_FORMAT_PARAMS(hr),
2223 region_gc_time_stamp, _gc_time_stamp);
2224 _failures = true;
2225 }
2226 return false;
2227 }
2228
2229 bool failures() { return _failures; }
2230 };
2231
2232 void G1CollectedHeap::check_gc_time_stamps() {
2233 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2234 heap_region_iterate(&cl);
2235 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2236 }
2237 #endif // PRODUCT
2238
2239 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2240 _cg1r->hot_card_cache()->drain(cl, worker_i);
2241 }
2242
2243 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2244 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2245 size_t n_completed_buffers = 0;
2246 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2247 n_completed_buffers++;
2248 }
2249 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2250 dcqs.clear_n_completed_buffers();
2251 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2252 }
2253
2254 // Computes the sum of the storage used by the various regions.
2255 size_t G1CollectedHeap::used() const {
2256 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2257 if (_archive_allocator != NULL) {
2258 result += _archive_allocator->used();
2259 }
2260 return result;
2261 }
2262
2263 size_t G1CollectedHeap::used_unlocked() const {
2264 return _summary_bytes_used;
2265 }
2266
2267 class SumUsedClosure: public HeapRegionClosure {
2268 size_t _used;
2269 public:
2270 SumUsedClosure() : _used(0) {}
2271 bool doHeapRegion(HeapRegion* r) {
2272 _used += r->used();
2273 return false;
2274 }
2275 size_t result() { return _used; }
2276 };
2277
2278 size_t G1CollectedHeap::recalculate_used() const {
2279 double recalculate_used_start = os::elapsedTime();
2280
2281 SumUsedClosure blk;
2282 heap_region_iterate(&blk);
2283
2284 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2285 return blk.result();
2286 }
2287
2288 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2289 switch (cause) {
2290 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2291 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2292 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2293 case GCCause::_g1_humongous_allocation: return true;
2294 case GCCause::_update_allocation_context_stats_inc: return true;
2295 case GCCause::_wb_conc_mark: return true;
2296 default: return false;
2297 }
2298 }
2299
2300 #ifndef PRODUCT
2301 void G1CollectedHeap::allocate_dummy_regions() {
2302 // Let's fill up most of the region
2303 size_t word_size = HeapRegion::GrainWords - 1024;
2304 // And as a result the region we'll allocate will be humongous.
2305 guarantee(is_humongous(word_size), "sanity");
2306
2307 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2308 // Let's use the existing mechanism for the allocation
2309 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2310 AllocationContext::system());
2311 if (dummy_obj != NULL) {
2312 MemRegion mr(dummy_obj, word_size);
2313 CollectedHeap::fill_with_object(mr);
2314 } else {
2315 // If we can't allocate once, we probably cannot allocate
2316 // again. Let's get out of the loop.
2317 break;
2318 }
2319 }
2320 }
2321 #endif // !PRODUCT
2322
2323 void G1CollectedHeap::increment_old_marking_cycles_started() {
2324 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2325 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2326 "Wrong marking cycle count (started: %d, completed: %d)",
2327 _old_marking_cycles_started, _old_marking_cycles_completed);
2328
2329 _old_marking_cycles_started++;
2330 }
2331
2332 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2333 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2334
2335 // We assume that if concurrent == true, then the caller is a
2336 // concurrent thread that was joined the Suspendible Thread
2337 // Set. If there's ever a cheap way to check this, we should add an
2338 // assert here.
2339
2340 // Given that this method is called at the end of a Full GC or of a
2341 // concurrent cycle, and those can be nested (i.e., a Full GC can
2342 // interrupt a concurrent cycle), the number of full collections
2343 // completed should be either one (in the case where there was no
2344 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2345 // behind the number of full collections started.
2346
2347 // This is the case for the inner caller, i.e. a Full GC.
2348 assert(concurrent ||
2349 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2350 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2351 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2352 "is inconsistent with _old_marking_cycles_completed = %u",
2353 _old_marking_cycles_started, _old_marking_cycles_completed);
2354
2355 // This is the case for the outer caller, i.e. the concurrent cycle.
2356 assert(!concurrent ||
2357 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2358 "for outer caller (concurrent cycle): "
2359 "_old_marking_cycles_started = %u "
2360 "is inconsistent with _old_marking_cycles_completed = %u",
2361 _old_marking_cycles_started, _old_marking_cycles_completed);
2362
2363 _old_marking_cycles_completed += 1;
2364
2365 // We need to clear the "in_progress" flag in the CM thread before
2366 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2367 // is set) so that if a waiter requests another System.gc() it doesn't
2368 // incorrectly see that a marking cycle is still in progress.
2369 if (concurrent) {
2370 _cmThread->set_idle();
2371 }
2372
2373 // This notify_all() will ensure that a thread that called
2374 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2375 // and it's waiting for a full GC to finish will be woken up. It is
2376 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2377 FullGCCount_lock->notify_all();
2378 }
2379
2380 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2381 GCIdMarkAndRestore conc_gc_id_mark;
2382 collector_state()->set_concurrent_cycle_started(true);
2383 _gc_timer_cm->register_gc_start(start_time);
2384
2385 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2386 trace_heap_before_gc(_gc_tracer_cm);
2387 _cmThread->set_gc_id(GCId::current());
2388 }
2389
2390 void G1CollectedHeap::register_concurrent_cycle_end() {
2391 if (collector_state()->concurrent_cycle_started()) {
2392 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2393 if (_cm->has_aborted()) {
2394 _gc_tracer_cm->report_concurrent_mode_failure();
2395 }
2396
2397 _gc_timer_cm->register_gc_end();
2398 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2399
2400 // Clear state variables to prepare for the next concurrent cycle.
2401 collector_state()->set_concurrent_cycle_started(false);
2402 _heap_summary_sent = false;
2403 }
2404 }
2405
2406 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2407 if (collector_state()->concurrent_cycle_started()) {
2408 // This function can be called when:
2409 // the cleanup pause is run
2410 // the concurrent cycle is aborted before the cleanup pause.
2411 // the concurrent cycle is aborted after the cleanup pause,
2412 // but before the concurrent cycle end has been registered.
2413 // Make sure that we only send the heap information once.
2414 if (!_heap_summary_sent) {
2415 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2416 trace_heap_after_gc(_gc_tracer_cm);
2417 _heap_summary_sent = true;
2418 }
2419 }
2420 }
2421
2422 void G1CollectedHeap::collect(GCCause::Cause cause) {
2423 assert_heap_not_locked();
2424
2425 uint gc_count_before;
2426 uint old_marking_count_before;
2427 uint full_gc_count_before;
2428 bool retry_gc;
2429
2430 do {
2431 retry_gc = false;
2432
2433 {
2434 MutexLocker ml(Heap_lock);
2435
2436 // Read the GC count while holding the Heap_lock
2437 gc_count_before = total_collections();
2438 full_gc_count_before = total_full_collections();
2439 old_marking_count_before = _old_marking_cycles_started;
2440 }
2441
2442 if (should_do_concurrent_full_gc(cause)) {
2443 // Schedule an initial-mark evacuation pause that will start a
2444 // concurrent cycle. We're setting word_size to 0 which means that
2445 // we are not requesting a post-GC allocation.
2446 VM_G1IncCollectionPause op(gc_count_before,
2447 0, /* word_size */
2448 true, /* should_initiate_conc_mark */
2449 g1_policy()->max_pause_time_ms(),
2450 cause);
2451 op.set_allocation_context(AllocationContext::current());
2452
2453 VMThread::execute(&op);
2454 if (!op.pause_succeeded()) {
2455 if (old_marking_count_before == _old_marking_cycles_started) {
2456 retry_gc = op.should_retry_gc();
2457 } else {
2458 // A Full GC happened while we were trying to schedule the
2459 // initial-mark GC. No point in starting a new cycle given
2460 // that the whole heap was collected anyway.
2461 }
2462
2463 if (retry_gc) {
2464 if (GC_locker::is_active_and_needs_gc()) {
2465 GC_locker::stall_until_clear();
2466 }
2467 }
2468 }
2469 } else {
2470 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2471 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2472
2473 // Schedule a standard evacuation pause. We're setting word_size
2474 // to 0 which means that we are not requesting a post-GC allocation.
2475 VM_G1IncCollectionPause op(gc_count_before,
2476 0, /* word_size */
2477 false, /* should_initiate_conc_mark */
2478 g1_policy()->max_pause_time_ms(),
2479 cause);
2480 VMThread::execute(&op);
2481 } else {
2482 // Schedule a Full GC.
2483 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2484 VMThread::execute(&op);
2485 }
2486 }
2487 } while (retry_gc);
2488 }
2489
2490 bool G1CollectedHeap::is_in(const void* p) const {
2491 if (_hrm.reserved().contains(p)) {
2492 // Given that we know that p is in the reserved space,
2493 // heap_region_containing() should successfully
2494 // return the containing region.
2495 HeapRegion* hr = heap_region_containing(p);
2496 return hr->is_in(p);
2497 } else {
2498 return false;
2499 }
2500 }
2501
2502 #ifdef ASSERT
2503 bool G1CollectedHeap::is_in_exact(const void* p) const {
2504 bool contains = reserved_region().contains(p);
2505 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2506 if (contains && available) {
2507 return true;
2508 } else {
2509 return false;
2510 }
2511 }
2512 #endif
2513
2514 bool G1CollectedHeap::obj_in_cs(oop obj) {
2515 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2516 return r != NULL && r->in_collection_set();
2517 }
2518
2519 // Iteration functions.
2520
2521 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2522
2523 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2524 ExtendedOopClosure* _cl;
2525 public:
2526 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2527 bool doHeapRegion(HeapRegion* r) {
2528 if (!r->is_continues_humongous()) {
2529 r->oop_iterate(_cl);
2530 }
2531 return false;
2532 }
2533 };
2534
2535 // Iterates an ObjectClosure over all objects within a HeapRegion.
2536
2537 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2538 ObjectClosure* _cl;
2539 public:
2540 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2541 bool doHeapRegion(HeapRegion* r) {
2542 if (!r->is_continues_humongous()) {
2543 r->object_iterate(_cl);
2544 }
2545 return false;
2546 }
2547 };
2548
2549 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2550 IterateObjectClosureRegionClosure blk(cl);
2551 heap_region_iterate(&blk);
2552 }
2553
2554 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2555 _hrm.iterate(cl);
2556 }
2557
2558 void
2559 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2560 uint worker_id,
2561 HeapRegionClaimer *hrclaimer,
2562 bool concurrent) const {
2563 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2564 }
2565
2566 // Clear the cached CSet starting regions and (more importantly)
2567 // the time stamps. Called when we reset the GC time stamp.
2568 void G1CollectedHeap::clear_cset_start_regions() {
2569 assert(_worker_cset_start_region != NULL, "sanity");
2570 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2571
2572 for (uint i = 0; i < ParallelGCThreads; i++) {
2573 _worker_cset_start_region[i] = NULL;
2574 _worker_cset_start_region_time_stamp[i] = 0;
2575 }
2576 }
2577
2578 // Given the id of a worker, obtain or calculate a suitable
2579 // starting region for iterating over the current collection set.
2580 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2581 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2582
2583 HeapRegion* result = NULL;
2584 unsigned gc_time_stamp = get_gc_time_stamp();
2585
2586 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2587 // Cached starting region for current worker was set
2588 // during the current pause - so it's valid.
2589 // Note: the cached starting heap region may be NULL
2590 // (when the collection set is empty).
2591 result = _worker_cset_start_region[worker_i];
2592 assert(result == NULL || result->in_collection_set(), "sanity");
2593 return result;
2594 }
2595
2596 // The cached entry was not valid so let's calculate
2597 // a suitable starting heap region for this worker.
2598
2599 // We want the parallel threads to start their collection
2600 // set iteration at different collection set regions to
2601 // avoid contention.
2602 // If we have:
2603 // n collection set regions
2604 // p threads
2605 // Then thread t will start at region floor ((t * n) / p)
2606
2607 result = g1_policy()->collection_set();
2608 uint cs_size = g1_policy()->cset_region_length();
2609 uint active_workers = workers()->active_workers();
2610
2611 uint end_ind = (cs_size * worker_i) / active_workers;
2612 uint start_ind = 0;
2613
2614 if (worker_i > 0 &&
2615 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2616 // Previous workers starting region is valid
2617 // so let's iterate from there
2618 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2619 result = _worker_cset_start_region[worker_i - 1];
2620 }
2621
2622 for (uint i = start_ind; i < end_ind; i++) {
2623 result = result->next_in_collection_set();
2624 }
2625
2626 // Note: the calculated starting heap region may be NULL
2627 // (when the collection set is empty).
2628 assert(result == NULL || result->in_collection_set(), "sanity");
2629 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2630 "should be updated only once per pause");
2631 _worker_cset_start_region[worker_i] = result;
2632 OrderAccess::storestore();
2633 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2634 return result;
2635 }
2636
2637 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2638 HeapRegion* r = g1_policy()->collection_set();
2639 while (r != NULL) {
2640 HeapRegion* next = r->next_in_collection_set();
2641 if (cl->doHeapRegion(r)) {
2642 cl->incomplete();
2643 return;
2644 }
2645 r = next;
2646 }
2647 }
2648
2649 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2650 HeapRegionClosure *cl) {
2651 if (r == NULL) {
2652 // The CSet is empty so there's nothing to do.
2653 return;
2654 }
2655
2656 assert(r->in_collection_set(),
2657 "Start region must be a member of the collection set.");
2658 HeapRegion* cur = r;
2659 while (cur != NULL) {
2660 HeapRegion* next = cur->next_in_collection_set();
2661 if (cl->doHeapRegion(cur) && false) {
2662 cl->incomplete();
2663 return;
2664 }
2665 cur = next;
2666 }
2667 cur = g1_policy()->collection_set();
2668 while (cur != r) {
2669 HeapRegion* next = cur->next_in_collection_set();
2670 if (cl->doHeapRegion(cur) && false) {
2671 cl->incomplete();
2672 return;
2673 }
2674 cur = next;
2675 }
2676 }
2677
2678 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2679 HeapRegion* result = _hrm.next_region_in_heap(from);
2680 while (result != NULL && result->is_pinned()) {
2681 result = _hrm.next_region_in_heap(result);
2682 }
2683 return result;
2684 }
2685
2686 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2687 HeapRegion* hr = heap_region_containing(addr);
2688 return hr->block_start(addr);
2689 }
2690
2691 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2692 HeapRegion* hr = heap_region_containing(addr);
2693 return hr->block_size(addr);
2694 }
2695
2696 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2697 HeapRegion* hr = heap_region_containing(addr);
2698 return hr->block_is_obj(addr);
2699 }
2700
2701 bool G1CollectedHeap::supports_tlab_allocation() const {
2702 return true;
2703 }
2704
2705 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2706 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2707 }
2708
2709 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2710 return young_list()->eden_used_bytes();
2711 }
2712
2713 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2714 // must be equal to the humongous object limit.
2715 size_t G1CollectedHeap::max_tlab_size() const {
2716 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2717 }
2718
2719 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2720 AllocationContext_t context = AllocationContext::current();
2721 return _allocator->unsafe_max_tlab_alloc(context);
2722 }
2723
2724 size_t G1CollectedHeap::max_capacity() const {
2725 return _hrm.reserved().byte_size();
2726 }
2727
2728 jlong G1CollectedHeap::millis_since_last_gc() {
2729 // assert(false, "NYI");
2730 return 0;
2731 }
2732
2733 void G1CollectedHeap::prepare_for_verify() {
2734 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2735 ensure_parsability(false);
2736 }
2737 g1_rem_set()->prepare_for_verify();
2738 }
2739
2740 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2741 VerifyOption vo) {
2742 switch (vo) {
2743 case VerifyOption_G1UsePrevMarking:
2744 return hr->obj_allocated_since_prev_marking(obj);
2745 case VerifyOption_G1UseNextMarking:
2746 return hr->obj_allocated_since_next_marking(obj);
2747 case VerifyOption_G1UseMarkWord:
2748 return false;
2749 default:
2750 ShouldNotReachHere();
2751 }
2752 return false; // keep some compilers happy
2753 }
2754
2755 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2756 switch (vo) {
2757 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2758 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2759 case VerifyOption_G1UseMarkWord: return NULL;
2760 default: ShouldNotReachHere();
2761 }
2762 return NULL; // keep some compilers happy
2763 }
2764
2765 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2766 switch (vo) {
2767 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2768 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2769 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2770 default: ShouldNotReachHere();
2771 }
2772 return false; // keep some compilers happy
2773 }
2774
2775 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2776 switch (vo) {
2777 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2778 case VerifyOption_G1UseNextMarking: return "NTAMS";
2779 case VerifyOption_G1UseMarkWord: return "NONE";
2780 default: ShouldNotReachHere();
2781 }
2782 return NULL; // keep some compilers happy
2783 }
2784
2785 class VerifyRootsClosure: public OopClosure {
2786 private:
2787 G1CollectedHeap* _g1h;
2788 VerifyOption _vo;
2789 bool _failures;
2790 public:
2791 // _vo == UsePrevMarking -> use "prev" marking information,
2792 // _vo == UseNextMarking -> use "next" marking information,
2793 // _vo == UseMarkWord -> use mark word from object header.
2794 VerifyRootsClosure(VerifyOption vo) :
2795 _g1h(G1CollectedHeap::heap()),
2796 _vo(vo),
2797 _failures(false) { }
2798
2799 bool failures() { return _failures; }
2800
2801 template <class T> void do_oop_nv(T* p) {
2802 T heap_oop = oopDesc::load_heap_oop(p);
2803 if (!oopDesc::is_null(heap_oop)) {
2804 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2805 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2806 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2807 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2808 if (_vo == VerifyOption_G1UseMarkWord) {
2809 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2810 }
2811 obj->print_on(gclog_or_tty);
2812 _failures = true;
2813 }
2814 }
2815 }
2816
2817 void do_oop(oop* p) { do_oop_nv(p); }
2818 void do_oop(narrowOop* p) { do_oop_nv(p); }
2819 };
2820
2821 class G1VerifyCodeRootOopClosure: public OopClosure {
2822 G1CollectedHeap* _g1h;
2823 OopClosure* _root_cl;
2824 nmethod* _nm;
2825 VerifyOption _vo;
2826 bool _failures;
2827
2828 template <class T> void do_oop_work(T* p) {
2829 // First verify that this root is live
2830 _root_cl->do_oop(p);
2831
2832 if (!G1VerifyHeapRegionCodeRoots) {
2833 // We're not verifying the code roots attached to heap region.
2834 return;
2835 }
2836
2837 // Don't check the code roots during marking verification in a full GC
2838 if (_vo == VerifyOption_G1UseMarkWord) {
2839 return;
2840 }
2841
2842 // Now verify that the current nmethod (which contains p) is
2843 // in the code root list of the heap region containing the
2844 // object referenced by p.
2845
2846 T heap_oop = oopDesc::load_heap_oop(p);
2847 if (!oopDesc::is_null(heap_oop)) {
2848 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2849
2850 // Now fetch the region containing the object
2851 HeapRegion* hr = _g1h->heap_region_containing(obj);
2852 HeapRegionRemSet* hrrs = hr->rem_set();
2853 // Verify that the strong code root list for this region
2854 // contains the nmethod
2855 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2856 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2857 "from nmethod " PTR_FORMAT " not in strong "
2858 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2859 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2860 _failures = true;
2861 }
2862 }
2863 }
2864
2865 public:
2866 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2867 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2868
2869 void do_oop(oop* p) { do_oop_work(p); }
2870 void do_oop(narrowOop* p) { do_oop_work(p); }
2871
2872 void set_nmethod(nmethod* nm) { _nm = nm; }
2873 bool failures() { return _failures; }
2874 };
2875
2876 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2877 G1VerifyCodeRootOopClosure* _oop_cl;
2878
2879 public:
2880 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2881 _oop_cl(oop_cl) {}
2882
2883 void do_code_blob(CodeBlob* cb) {
2884 nmethod* nm = cb->as_nmethod_or_null();
2885 if (nm != NULL) {
2886 _oop_cl->set_nmethod(nm);
2887 nm->oops_do(_oop_cl);
2888 }
2889 }
2890 };
2891
2892 class YoungRefCounterClosure : public OopClosure {
2893 G1CollectedHeap* _g1h;
2894 int _count;
2895 public:
2896 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2897 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2898 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2899
2900 int count() { return _count; }
2901 void reset_count() { _count = 0; };
2902 };
2903
2904 class VerifyKlassClosure: public KlassClosure {
2905 YoungRefCounterClosure _young_ref_counter_closure;
2906 OopClosure *_oop_closure;
2907 public:
2908 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2909 void do_klass(Klass* k) {
2910 k->oops_do(_oop_closure);
2911
2912 _young_ref_counter_closure.reset_count();
2913 k->oops_do(&_young_ref_counter_closure);
2914 if (_young_ref_counter_closure.count() > 0) {
2915 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2916 }
2917 }
2918 };
2919
2920 class VerifyLivenessOopClosure: public OopClosure {
2921 G1CollectedHeap* _g1h;
2922 VerifyOption _vo;
2923 public:
2924 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2925 _g1h(g1h), _vo(vo)
2926 { }
2927 void do_oop(narrowOop *p) { do_oop_work(p); }
2928 void do_oop( oop *p) { do_oop_work(p); }
2929
2930 template <class T> void do_oop_work(T *p) {
2931 oop obj = oopDesc::load_decode_heap_oop(p);
2932 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2933 "Dead object referenced by a not dead object");
2934 }
2935 };
2936
2937 class VerifyObjsInRegionClosure: public ObjectClosure {
2938 private:
2939 G1CollectedHeap* _g1h;
2940 size_t _live_bytes;
2941 HeapRegion *_hr;
2942 VerifyOption _vo;
2943 public:
2944 // _vo == UsePrevMarking -> use "prev" marking information,
2945 // _vo == UseNextMarking -> use "next" marking information,
2946 // _vo == UseMarkWord -> use mark word from object header.
2947 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2948 : _live_bytes(0), _hr(hr), _vo(vo) {
2949 _g1h = G1CollectedHeap::heap();
2950 }
2951 void do_object(oop o) {
2952 VerifyLivenessOopClosure isLive(_g1h, _vo);
2953 assert(o != NULL, "Huh?");
2954 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2955 // If the object is alive according to the mark word,
2956 // then verify that the marking information agrees.
2957 // Note we can't verify the contra-positive of the
2958 // above: if the object is dead (according to the mark
2959 // word), it may not be marked, or may have been marked
2960 // but has since became dead, or may have been allocated
2961 // since the last marking.
2962 if (_vo == VerifyOption_G1UseMarkWord) {
2963 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2964 }
2965
2966 o->oop_iterate_no_header(&isLive);
2967 if (!_hr->obj_allocated_since_prev_marking(o)) {
2968 size_t obj_size = o->size(); // Make sure we don't overflow
2969 _live_bytes += (obj_size * HeapWordSize);
2970 }
2971 }
2972 }
2973 size_t live_bytes() { return _live_bytes; }
2974 };
2975
2976 class VerifyArchiveOopClosure: public OopClosure {
2977 public:
2978 VerifyArchiveOopClosure(HeapRegion *hr) { }
2979 void do_oop(narrowOop *p) { do_oop_work(p); }
2980 void do_oop( oop *p) { do_oop_work(p); }
2981
2982 template <class T> void do_oop_work(T *p) {
2983 oop obj = oopDesc::load_decode_heap_oop(p);
2984 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2985 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2986 p2i(p), p2i(obj));
2987 }
2988 };
2989
2990 class VerifyArchiveRegionClosure: public ObjectClosure {
2991 public:
2992 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2993 // Verify that all object pointers are to archive regions.
2994 void do_object(oop o) {
2995 VerifyArchiveOopClosure checkOop(NULL);
2996 assert(o != NULL, "Should not be here for NULL oops");
2997 o->oop_iterate_no_header(&checkOop);
2998 }
2999 };
3000
3001 class VerifyRegionClosure: public HeapRegionClosure {
3002 private:
3003 bool _par;
3004 VerifyOption _vo;
3005 bool _failures;
3006 public:
3007 // _vo == UsePrevMarking -> use "prev" marking information,
3008 // _vo == UseNextMarking -> use "next" marking information,
3009 // _vo == UseMarkWord -> use mark word from object header.
3010 VerifyRegionClosure(bool par, VerifyOption vo)
3011 : _par(par),
3012 _vo(vo),
3013 _failures(false) {}
3014
3015 bool failures() {
3016 return _failures;
3017 }
3018
3019 bool doHeapRegion(HeapRegion* r) {
3020 // For archive regions, verify there are no heap pointers to
3021 // non-pinned regions. For all others, verify liveness info.
3022 if (r->is_archive()) {
3023 VerifyArchiveRegionClosure verify_oop_pointers(r);
3024 r->object_iterate(&verify_oop_pointers);
3025 return true;
3026 }
3027 if (!r->is_continues_humongous()) {
3028 bool failures = false;
3029 r->verify(_vo, &failures);
3030 if (failures) {
3031 _failures = true;
3032 } else if (!r->is_starts_humongous()) {
3033 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3034 r->object_iterate(¬_dead_yet_cl);
3035 if (_vo != VerifyOption_G1UseNextMarking) {
3036 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3037 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3038 "max_live_bytes " SIZE_FORMAT " "
3039 "< calculated " SIZE_FORMAT,
3040 p2i(r->bottom()), p2i(r->end()),
3041 r->max_live_bytes(),
3042 not_dead_yet_cl.live_bytes());
3043 _failures = true;
3044 }
3045 } else {
3046 // When vo == UseNextMarking we cannot currently do a sanity
3047 // check on the live bytes as the calculation has not been
3048 // finalized yet.
3049 }
3050 }
3051 }
3052 return false; // stop the region iteration if we hit a failure
3053 }
3054 };
3055
3056 // This is the task used for parallel verification of the heap regions
3057
3058 class G1ParVerifyTask: public AbstractGangTask {
3059 private:
3060 G1CollectedHeap* _g1h;
3061 VerifyOption _vo;
3062 bool _failures;
3063 HeapRegionClaimer _hrclaimer;
3064
3065 public:
3066 // _vo == UsePrevMarking -> use "prev" marking information,
3067 // _vo == UseNextMarking -> use "next" marking information,
3068 // _vo == UseMarkWord -> use mark word from object header.
3069 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3070 AbstractGangTask("Parallel verify task"),
3071 _g1h(g1h),
3072 _vo(vo),
3073 _failures(false),
3074 _hrclaimer(g1h->workers()->active_workers()) {}
3075
3076 bool failures() {
3077 return _failures;
3078 }
3079
3080 void work(uint worker_id) {
3081 HandleMark hm;
3082 VerifyRegionClosure blk(true, _vo);
3083 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3084 if (blk.failures()) {
3085 _failures = true;
3086 }
3087 }
3088 };
3089
3090 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3091 if (SafepointSynchronize::is_at_safepoint()) {
3092 assert(Thread::current()->is_VM_thread(),
3093 "Expected to be executed serially by the VM thread at this point");
3094
3095 if (!silent) { gclog_or_tty->print("Roots "); }
3096 VerifyRootsClosure rootsCl(vo);
3097 VerifyKlassClosure klassCl(this, &rootsCl);
3098 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3099
3100 // We apply the relevant closures to all the oops in the
3101 // system dictionary, class loader data graph, the string table
3102 // and the nmethods in the code cache.
3103 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3104 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3105
3106 {
3107 G1RootProcessor root_processor(this, 1);
3108 root_processor.process_all_roots(&rootsCl,
3109 &cldCl,
3110 &blobsCl);
3111 }
3112
3113 bool failures = rootsCl.failures() || codeRootsCl.failures();
3114
3115 if (vo != VerifyOption_G1UseMarkWord) {
3116 // If we're verifying during a full GC then the region sets
3117 // will have been torn down at the start of the GC. Therefore
3118 // verifying the region sets will fail. So we only verify
3119 // the region sets when not in a full GC.
3120 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3121 verify_region_sets();
3122 }
3123
3124 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3125 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3126
3127 G1ParVerifyTask task(this, vo);
3128 workers()->run_task(&task);
3129 if (task.failures()) {
3130 failures = true;
3131 }
3132
3133 } else {
3134 VerifyRegionClosure blk(false, vo);
3135 heap_region_iterate(&blk);
3136 if (blk.failures()) {
3137 failures = true;
3138 }
3139 }
3140
3141 if (G1StringDedup::is_enabled()) {
3142 if (!silent) gclog_or_tty->print("StrDedup ");
3143 G1StringDedup::verify();
3144 }
3145
3146 if (failures) {
3147 gclog_or_tty->print_cr("Heap:");
3148 // It helps to have the per-region information in the output to
3149 // help us track down what went wrong. This is why we call
3150 // print_extended_on() instead of print_on().
3151 print_extended_on(gclog_or_tty);
3152 gclog_or_tty->cr();
3153 gclog_or_tty->flush();
3154 }
3155 guarantee(!failures, "there should not have been any failures");
3156 } else {
3157 if (!silent) {
3158 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3159 if (G1StringDedup::is_enabled()) {
3160 gclog_or_tty->print(", StrDedup");
3161 }
3162 gclog_or_tty->print(") ");
3163 }
3164 }
3165 }
3166
3167 void G1CollectedHeap::verify(bool silent) {
3168 verify(silent, VerifyOption_G1UsePrevMarking);
3169 }
3170
3171 double G1CollectedHeap::verify(bool guard, const char* msg) {
3172 double verify_time_ms = 0.0;
3173
3174 if (guard && total_collections() >= VerifyGCStartAt) {
3175 double verify_start = os::elapsedTime();
3176 HandleMark hm; // Discard invalid handles created during verification
3177 prepare_for_verify();
3178 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3179 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3180 }
3181
3182 return verify_time_ms;
3183 }
3184
3185 void G1CollectedHeap::verify_before_gc() {
3186 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3187 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3188 }
3189
3190 void G1CollectedHeap::verify_after_gc() {
3191 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3192 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3193 }
3194
3195 class PrintRegionClosure: public HeapRegionClosure {
3196 outputStream* _st;
3197 public:
3198 PrintRegionClosure(outputStream* st) : _st(st) {}
3199 bool doHeapRegion(HeapRegion* r) {
3200 r->print_on(_st);
3201 return false;
3202 }
3203 };
3204
3205 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3206 const HeapRegion* hr,
3207 const VerifyOption vo) const {
3208 switch (vo) {
3209 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3210 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3211 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3212 default: ShouldNotReachHere();
3213 }
3214 return false; // keep some compilers happy
3215 }
3216
3217 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3218 const VerifyOption vo) const {
3219 switch (vo) {
3220 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3221 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3222 case VerifyOption_G1UseMarkWord: {
3223 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3224 return !obj->is_gc_marked() && !hr->is_archive();
3225 }
3226 default: ShouldNotReachHere();
3227 }
3228 return false; // keep some compilers happy
3229 }
3230
3231 void G1CollectedHeap::print_on(outputStream* st) const {
3232 st->print(" %-20s", "garbage-first heap");
3233 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3234 capacity()/K, used_unlocked()/K);
3235 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3236 p2i(_hrm.reserved().start()),
3237 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3238 p2i(_hrm.reserved().end()));
3239 st->cr();
3240 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3241 uint young_regions = _young_list->length();
3242 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3243 (size_t) young_regions * HeapRegion::GrainBytes / K);
3244 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3245 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3246 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3247 st->cr();
3248 MetaspaceAux::print_on(st);
3249 }
3250
3251 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3252 print_on(st);
3253
3254 // Print the per-region information.
3255 st->cr();
3256 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3257 "HS=humongous(starts), HC=humongous(continues), "
3258 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3259 "PTAMS=previous top-at-mark-start, "
3260 "NTAMS=next top-at-mark-start)");
3261 PrintRegionClosure blk(st);
3262 heap_region_iterate(&blk);
3263 }
3264
3265 void G1CollectedHeap::print_on_error(outputStream* st) const {
3266 this->CollectedHeap::print_on_error(st);
3267
3268 if (_cm != NULL) {
3269 st->cr();
3270 _cm->print_on_error(st);
3271 }
3272 }
3273
3274 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3275 workers()->print_worker_threads_on(st);
3276 _cmThread->print_on(st);
3277 st->cr();
3278 _cm->print_worker_threads_on(st);
3279 _cg1r->print_worker_threads_on(st);
3280 if (G1StringDedup::is_enabled()) {
3281 G1StringDedup::print_worker_threads_on(st);
3282 }
3283 }
3284
3285 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3286 workers()->threads_do(tc);
3287 tc->do_thread(_cmThread);
3288 _cg1r->threads_do(tc);
3289 if (G1StringDedup::is_enabled()) {
3290 G1StringDedup::threads_do(tc);
3291 }
3292 }
3293
3294 void G1CollectedHeap::print_tracing_info() const {
3295 // We'll overload this to mean "trace GC pause statistics."
3296 if (TraceYoungGenTime || TraceOldGenTime) {
3297 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3298 // to that.
3299 g1_policy()->print_tracing_info();
3300 }
3301 if (G1SummarizeRSetStats) {
3302 g1_rem_set()->print_summary_info();
3303 }
3304 if (G1SummarizeConcMark) {
3305 concurrent_mark()->print_summary_info();
3306 }
3307 g1_policy()->print_yg_surv_rate_info();
3308 }
3309
3310 #ifndef PRODUCT
3311 // Helpful for debugging RSet issues.
3312
3313 class PrintRSetsClosure : public HeapRegionClosure {
3314 private:
3315 const char* _msg;
3316 size_t _occupied_sum;
3317
3318 public:
3319 bool doHeapRegion(HeapRegion* r) {
3320 HeapRegionRemSet* hrrs = r->rem_set();
3321 size_t occupied = hrrs->occupied();
3322 _occupied_sum += occupied;
3323
3324 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3325 HR_FORMAT_PARAMS(r));
3326 if (occupied == 0) {
3327 gclog_or_tty->print_cr(" RSet is empty");
3328 } else {
3329 hrrs->print();
3330 }
3331 gclog_or_tty->print_cr("----------");
3332 return false;
3333 }
3334
3335 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3336 gclog_or_tty->cr();
3337 gclog_or_tty->print_cr("========================================");
3338 gclog_or_tty->print_cr("%s", msg);
3339 gclog_or_tty->cr();
3340 }
3341
3342 ~PrintRSetsClosure() {
3343 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3344 gclog_or_tty->print_cr("========================================");
3345 gclog_or_tty->cr();
3346 }
3347 };
3348
3349 void G1CollectedHeap::print_cset_rsets() {
3350 PrintRSetsClosure cl("Printing CSet RSets");
3351 collection_set_iterate(&cl);
3352 }
3353
3354 void G1CollectedHeap::print_all_rsets() {
3355 PrintRSetsClosure cl("Printing All RSets");;
3356 heap_region_iterate(&cl);
3357 }
3358 #endif // PRODUCT
3359
3360 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3361 YoungList* young_list = heap()->young_list();
3362
3363 size_t eden_used_bytes = young_list->eden_used_bytes();
3364 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3365
3366 size_t eden_capacity_bytes =
3367 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3368
3369 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3370 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3371 }
3372
3373 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3374 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3375 stats->unused(), stats->used(), stats->region_end_waste(),
3376 stats->regions_filled(), stats->direct_allocated(),
3377 stats->failure_used(), stats->failure_waste());
3378 }
3379
3380 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3381 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3382 gc_tracer->report_gc_heap_summary(when, heap_summary);
3383
3384 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3385 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3386 }
3387
3388
3389 G1CollectedHeap* G1CollectedHeap::heap() {
3390 CollectedHeap* heap = Universe::heap();
3391 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3392 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3393 return (G1CollectedHeap*)heap;
3394 }
3395
3396 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3397 // always_do_update_barrier = false;
3398 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3399 // Fill TLAB's and such
3400 accumulate_statistics_all_tlabs();
3401 ensure_parsability(true);
3402
3403 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3404 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3405 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3406 }
3407 }
3408
3409 void G1CollectedHeap::gc_epilogue(bool full) {
3410
3411 if (G1SummarizeRSetStats &&
3412 (G1SummarizeRSetStatsPeriod > 0) &&
3413 // we are at the end of the GC. Total collections has already been increased.
3414 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3415 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3416 }
3417
3418 // FIXME: what is this about?
3419 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3420 // is set.
3421 #if defined(COMPILER2) || INCLUDE_JVMCI
3422 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3423 #endif
3424 // always_do_update_barrier = true;
3425
3426 resize_all_tlabs();
3427 allocation_context_stats().update(full);
3428
3429 // We have just completed a GC. Update the soft reference
3430 // policy with the new heap occupancy
3431 Universe::update_heap_info_at_gc();
3432 }
3433
3434 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3435 uint gc_count_before,
3436 bool* succeeded,
3437 GCCause::Cause gc_cause) {
3438 assert_heap_not_locked_and_not_at_safepoint();
3439 g1_policy()->record_stop_world_start();
3440 VM_G1IncCollectionPause op(gc_count_before,
3441 word_size,
3442 false, /* should_initiate_conc_mark */
3443 g1_policy()->max_pause_time_ms(),
3444 gc_cause);
3445
3446 op.set_allocation_context(AllocationContext::current());
3447 VMThread::execute(&op);
3448
3449 HeapWord* result = op.result();
3450 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3451 assert(result == NULL || ret_succeeded,
3452 "the result should be NULL if the VM did not succeed");
3453 *succeeded = ret_succeeded;
3454
3455 assert_heap_not_locked();
3456 return result;
3457 }
3458
3459 void
3460 G1CollectedHeap::doConcurrentMark() {
3461 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3462 if (!_cmThread->in_progress()) {
3463 _cmThread->set_started();
3464 CGC_lock->notify();
3465 }
3466 }
3467
3468 size_t G1CollectedHeap::pending_card_num() {
3469 size_t extra_cards = 0;
3470 JavaThread *curr = Threads::first();
3471 while (curr != NULL) {
3472 DirtyCardQueue& dcq = curr->dirty_card_queue();
3473 extra_cards += dcq.size();
3474 curr = curr->next();
3475 }
3476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3477 size_t buffer_size = dcqs.buffer_size();
3478 size_t buffer_num = dcqs.completed_buffers_num();
3479
3480 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3481 // in bytes - not the number of 'entries'. We need to convert
3482 // into a number of cards.
3483 return (buffer_size * buffer_num + extra_cards) / oopSize;
3484 }
3485
3486 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3487 private:
3488 size_t _total_humongous;
3489 size_t _candidate_humongous;
3490
3491 DirtyCardQueue _dcq;
3492
3493 // We don't nominate objects with many remembered set entries, on
3494 // the assumption that such objects are likely still live.
3495 bool is_remset_small(HeapRegion* region) const {
3496 HeapRegionRemSet* const rset = region->rem_set();
3497 return G1EagerReclaimHumongousObjectsWithStaleRefs
3498 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3499 : rset->is_empty();
3500 }
3501
3502 bool is_typeArray_region(HeapRegion* region) const {
3503 return oop(region->bottom())->is_typeArray();
3504 }
3505
3506 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3507 assert(region->is_starts_humongous(), "Must start a humongous object");
3508
3509 // Candidate selection must satisfy the following constraints
3510 // while concurrent marking is in progress:
3511 //
3512 // * In order to maintain SATB invariants, an object must not be
3513 // reclaimed if it was allocated before the start of marking and
3514 // has not had its references scanned. Such an object must have
3515 // its references (including type metadata) scanned to ensure no
3516 // live objects are missed by the marking process. Objects
3517 // allocated after the start of concurrent marking don't need to
3518 // be scanned.
3519 //
3520 // * An object must not be reclaimed if it is on the concurrent
3521 // mark stack. Objects allocated after the start of concurrent
3522 // marking are never pushed on the mark stack.
3523 //
3524 // Nominating only objects allocated after the start of concurrent
3525 // marking is sufficient to meet both constraints. This may miss
3526 // some objects that satisfy the constraints, but the marking data
3527 // structures don't support efficiently performing the needed
3528 // additional tests or scrubbing of the mark stack.
3529 //
3530 // However, we presently only nominate is_typeArray() objects.
3531 // A humongous object containing references induces remembered
3532 // set entries on other regions. In order to reclaim such an
3533 // object, those remembered sets would need to be cleaned up.
3534 //
3535 // We also treat is_typeArray() objects specially, allowing them
3536 // to be reclaimed even if allocated before the start of
3537 // concurrent mark. For this we rely on mark stack insertion to
3538 // exclude is_typeArray() objects, preventing reclaiming an object
3539 // that is in the mark stack. We also rely on the metadata for
3540 // such objects to be built-in and so ensured to be kept live.
3541 // Frequent allocation and drop of large binary blobs is an
3542 // important use case for eager reclaim, and this special handling
3543 // may reduce needed headroom.
3544
3545 return is_typeArray_region(region) && is_remset_small(region);
3546 }
3547
3548 public:
3549 RegisterHumongousWithInCSetFastTestClosure()
3550 : _total_humongous(0),
3551 _candidate_humongous(0),
3552 _dcq(&JavaThread::dirty_card_queue_set()) {
3553 }
3554
3555 virtual bool doHeapRegion(HeapRegion* r) {
3556 if (!r->is_starts_humongous()) {
3557 return false;
3558 }
3559 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3560
3561 bool is_candidate = humongous_region_is_candidate(g1h, r);
3562 uint rindex = r->hrm_index();
3563 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3564 if (is_candidate) {
3565 _candidate_humongous++;
3566 g1h->register_humongous_region_with_cset(rindex);
3567 // Is_candidate already filters out humongous object with large remembered sets.
3568 // If we have a humongous object with a few remembered sets, we simply flush these
3569 // remembered set entries into the DCQS. That will result in automatic
3570 // re-evaluation of their remembered set entries during the following evacuation
3571 // phase.
3572 if (!r->rem_set()->is_empty()) {
3573 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3574 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3575 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3576 HeapRegionRemSetIterator hrrs(r->rem_set());
3577 size_t card_index;
3578 while (hrrs.has_next(card_index)) {
3579 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3580 // The remembered set might contain references to already freed
3581 // regions. Filter out such entries to avoid failing card table
3582 // verification.
3583 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3584 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3585 *card_ptr = CardTableModRefBS::dirty_card_val();
3586 _dcq.enqueue(card_ptr);
3587 }
3588 }
3589 }
3590 r->rem_set()->clear_locked();
3591 }
3592 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3593 }
3594 _total_humongous++;
3595
3596 return false;
3597 }
3598
3599 size_t total_humongous() const { return _total_humongous; }
3600 size_t candidate_humongous() const { return _candidate_humongous; }
3601
3602 void flush_rem_set_entries() { _dcq.flush(); }
3603 };
3604
3605 void G1CollectedHeap::register_humongous_regions_with_cset() {
3606 if (!G1EagerReclaimHumongousObjects) {
3607 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3608 return;
3609 }
3610 double time = os::elapsed_counter();
3611
3612 // Collect reclaim candidate information and register candidates with cset.
3613 RegisterHumongousWithInCSetFastTestClosure cl;
3614 heap_region_iterate(&cl);
3615
3616 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3617 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3618 cl.total_humongous(),
3619 cl.candidate_humongous());
3620 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3621
3622 // Finally flush all remembered set entries to re-check into the global DCQS.
3623 cl.flush_rem_set_entries();
3624 }
3625
3626 #ifdef ASSERT
3627 class VerifyCSetClosure: public HeapRegionClosure {
3628 public:
3629 bool doHeapRegion(HeapRegion* hr) {
3630 // Here we check that the CSet region's RSet is ready for parallel
3631 // iteration. The fields that we'll verify are only manipulated
3632 // when the region is part of a CSet and is collected. Afterwards,
3633 // we reset these fields when we clear the region's RSet (when the
3634 // region is freed) so they are ready when the region is
3635 // re-allocated. The only exception to this is if there's an
3636 // evacuation failure and instead of freeing the region we leave
3637 // it in the heap. In that case, we reset these fields during
3638 // evacuation failure handling.
3639 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3640
3641 // Here's a good place to add any other checks we'd like to
3642 // perform on CSet regions.
3643 return false;
3644 }
3645 };
3646 #endif // ASSERT
3647
3648 uint G1CollectedHeap::num_task_queues() const {
3649 return _task_queues->size();
3650 }
3651
3652 #if TASKQUEUE_STATS
3653 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3654 st->print_raw_cr("GC Task Stats");
3655 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3656 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3657 }
3658
3659 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3660 print_taskqueue_stats_hdr(st);
3661
3662 TaskQueueStats totals;
3663 const uint n = num_task_queues();
3664 for (uint i = 0; i < n; ++i) {
3665 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3666 totals += task_queue(i)->stats;
3667 }
3668 st->print_raw("tot "); totals.print(st); st->cr();
3669
3670 DEBUG_ONLY(totals.verify());
3671 }
3672
3673 void G1CollectedHeap::reset_taskqueue_stats() {
3674 const uint n = num_task_queues();
3675 for (uint i = 0; i < n; ++i) {
3676 task_queue(i)->stats.reset();
3677 }
3678 }
3679 #endif // TASKQUEUE_STATS
3680
3681 void G1CollectedHeap::log_gc_header() {
3682 if (!G1Log::fine()) {
3683 return;
3684 }
3685
3686 gclog_or_tty->gclog_stamp();
3687
3688 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3689 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3690 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3691
3692 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3693 }
3694
3695 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3696 if (!G1Log::fine()) {
3697 return;
3698 }
3699
3700 if (G1Log::finer()) {
3701 if (evacuation_failed()) {
3702 gclog_or_tty->print(" (to-space exhausted)");
3703 }
3704 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3705 g1_policy()->print_phases(pause_time_sec);
3706 g1_policy()->print_detailed_heap_transition();
3707 } else {
3708 if (evacuation_failed()) {
3709 gclog_or_tty->print("--");
3710 }
3711 g1_policy()->print_heap_transition();
3712 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3713 }
3714 gclog_or_tty->flush();
3715 }
3716
3717 void G1CollectedHeap::wait_for_root_region_scanning() {
3718 double scan_wait_start = os::elapsedTime();
3719 // We have to wait until the CM threads finish scanning the
3720 // root regions as it's the only way to ensure that all the
3721 // objects on them have been correctly scanned before we start
3722 // moving them during the GC.
3723 bool waited = _cm->root_regions()->wait_until_scan_finished();
3724 double wait_time_ms = 0.0;
3725 if (waited) {
3726 double scan_wait_end = os::elapsedTime();
3727 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3728 }
3729 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3730 }
3731
3732 bool
3733 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3734 assert_at_safepoint(true /* should_be_vm_thread */);
3735 guarantee(!is_gc_active(), "collection is not reentrant");
3736
3737 if (GC_locker::check_active_before_gc()) {
3738 return false;
3739 }
3740
3741 _gc_timer_stw->register_gc_start();
3742
3743 GCIdMark gc_id_mark;
3744 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3745
3746 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3747 ResourceMark rm;
3748
3749 wait_for_root_region_scanning();
3750
3751 G1Log::update_level();
3752 print_heap_before_gc();
3753 trace_heap_before_gc(_gc_tracer_stw);
3754
3755 verify_region_sets_optional();
3756 verify_dirty_young_regions();
3757
3758 // This call will decide whether this pause is an initial-mark
3759 // pause. If it is, during_initial_mark_pause() will return true
3760 // for the duration of this pause.
3761 g1_policy()->decide_on_conc_mark_initiation();
3762
3763 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3764 assert(!collector_state()->during_initial_mark_pause() ||
3765 collector_state()->gcs_are_young(), "sanity");
3766
3767 // We also do not allow mixed GCs during marking.
3768 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3769
3770 // Record whether this pause is an initial mark. When the current
3771 // thread has completed its logging output and it's safe to signal
3772 // the CM thread, the flag's value in the policy has been reset.
3773 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3774
3775 // Inner scope for scope based logging, timers, and stats collection
3776 {
3777 EvacuationInfo evacuation_info;
3778
3779 if (collector_state()->during_initial_mark_pause()) {
3780 // We are about to start a marking cycle, so we increment the
3781 // full collection counter.
3782 increment_old_marking_cycles_started();
3783 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3784 }
3785
3786 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3787
3788 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3789
3790 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3791 workers()->active_workers(),
3792 Threads::number_of_non_daemon_threads());
3793 workers()->set_active_workers(active_workers);
3794
3795 double pause_start_sec = os::elapsedTime();
3796 g1_policy()->note_gc_start(active_workers);
3797 log_gc_header();
3798
3799 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3800 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3801
3802 // If the secondary_free_list is not empty, append it to the
3803 // free_list. No need to wait for the cleanup operation to finish;
3804 // the region allocation code will check the secondary_free_list
3805 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3806 // set, skip this step so that the region allocation code has to
3807 // get entries from the secondary_free_list.
3808 if (!G1StressConcRegionFreeing) {
3809 append_secondary_free_list_if_not_empty_with_lock();
3810 }
3811
3812 assert(check_young_list_well_formed(), "young list should be well formed");
3813
3814 // Don't dynamically change the number of GC threads this early. A value of
3815 // 0 is used to indicate serial work. When parallel work is done,
3816 // it will be set.
3817
3818 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3819 IsGCActiveMark x;
3820
3821 gc_prologue(false);
3822 increment_total_collections(false /* full gc */);
3823 increment_gc_time_stamp();
3824
3825 verify_before_gc();
3826
3827 check_bitmaps("GC Start");
3828
3829 #if defined(COMPILER2) || INCLUDE_JVMCI
3830 DerivedPointerTable::clear();
3831 #endif
3832
3833 // Please see comment in g1CollectedHeap.hpp and
3834 // G1CollectedHeap::ref_processing_init() to see how
3835 // reference processing currently works in G1.
3836
3837 // Enable discovery in the STW reference processor
3838 ref_processor_stw()->enable_discovery();
3839
3840 {
3841 // We want to temporarily turn off discovery by the
3842 // CM ref processor, if necessary, and turn it back on
3843 // on again later if we do. Using a scoped
3844 // NoRefDiscovery object will do this.
3845 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3846
3847 // Forget the current alloc region (we might even choose it to be part
3848 // of the collection set!).
3849 _allocator->release_mutator_alloc_region();
3850
3851 // We should call this after we retire the mutator alloc
3852 // region(s) so that all the ALLOC / RETIRE events are generated
3853 // before the start GC event.
3854 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3855
3856 // This timing is only used by the ergonomics to handle our pause target.
3857 // It is unclear why this should not include the full pause. We will
3858 // investigate this in CR 7178365.
3859 //
3860 // Preserving the old comment here if that helps the investigation:
3861 //
3862 // The elapsed time induced by the start time below deliberately elides
3863 // the possible verification above.
3864 double sample_start_time_sec = os::elapsedTime();
3865
3866 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3867
3868 if (collector_state()->during_initial_mark_pause()) {
3869 concurrent_mark()->checkpointRootsInitialPre();
3870 }
3871
3872 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3873 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3874
3875 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3876
3877 register_humongous_regions_with_cset();
3878
3879 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3880
3881 _cm->note_start_of_gc();
3882 // We call this after finalize_cset() to
3883 // ensure that the CSet has been finalized.
3884 _cm->verify_no_cset_oops();
3885
3886 if (_hr_printer.is_active()) {
3887 HeapRegion* hr = g1_policy()->collection_set();
3888 while (hr != NULL) {
3889 _hr_printer.cset(hr);
3890 hr = hr->next_in_collection_set();
3891 }
3892 }
3893
3894 #ifdef ASSERT
3895 VerifyCSetClosure cl;
3896 collection_set_iterate(&cl);
3897 #endif // ASSERT
3898
3899 // Initialize the GC alloc regions.
3900 _allocator->init_gc_alloc_regions(evacuation_info);
3901
3902 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3903 pre_evacuate_collection_set();
3904
3905 // Actually do the work...
3906 evacuate_collection_set(evacuation_info, &per_thread_states);
3907
3908 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3909
3910 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3911 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3912
3913 eagerly_reclaim_humongous_regions();
3914
3915 g1_policy()->clear_collection_set();
3916
3917 // Start a new incremental collection set for the next pause.
3918 g1_policy()->start_incremental_cset_building();
3919
3920 clear_cset_fast_test();
3921
3922 _young_list->reset_sampled_info();
3923
3924 // Don't check the whole heap at this point as the
3925 // GC alloc regions from this pause have been tagged
3926 // as survivors and moved on to the survivor list.
3927 // Survivor regions will fail the !is_young() check.
3928 assert(check_young_list_empty(false /* check_heap */),
3929 "young list should be empty");
3930
3931 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3932 _young_list->first_survivor_region(),
3933 _young_list->last_survivor_region());
3934
3935 _young_list->reset_auxilary_lists();
3936
3937 if (evacuation_failed()) {
3938 set_used(recalculate_used());
3939 if (_archive_allocator != NULL) {
3940 _archive_allocator->clear_used();
3941 }
3942 for (uint i = 0; i < ParallelGCThreads; i++) {
3943 if (_evacuation_failed_info_array[i].has_failed()) {
3944 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3945 }
3946 }
3947 } else {
3948 // The "used" of the the collection set have already been subtracted
3949 // when they were freed. Add in the bytes evacuated.
3950 increase_used(g1_policy()->bytes_copied_during_gc());
3951 }
3952
3953 if (collector_state()->during_initial_mark_pause()) {
3954 // We have to do this before we notify the CM threads that
3955 // they can start working to make sure that all the
3956 // appropriate initialization is done on the CM object.
3957 concurrent_mark()->checkpointRootsInitialPost();
3958 collector_state()->set_mark_in_progress(true);
3959 // Note that we don't actually trigger the CM thread at
3960 // this point. We do that later when we're sure that
3961 // the current thread has completed its logging output.
3962 }
3963
3964 allocate_dummy_regions();
3965
3966 _allocator->init_mutator_alloc_region();
3967
3968 {
3969 size_t expand_bytes = g1_policy()->expansion_amount();
3970 if (expand_bytes > 0) {
3971 size_t bytes_before = capacity();
3972 // No need for an ergo verbose message here,
3973 // expansion_amount() does this when it returns a value > 0.
3974 double expand_ms;
3975 if (!expand(expand_bytes, &expand_ms)) {
3976 // We failed to expand the heap. Cannot do anything about it.
3977 }
3978 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3979 }
3980 }
3981
3982 // We redo the verification but now wrt to the new CSet which
3983 // has just got initialized after the previous CSet was freed.
3984 _cm->verify_no_cset_oops();
3985 _cm->note_end_of_gc();
3986
3987 // This timing is only used by the ergonomics to handle our pause target.
3988 // It is unclear why this should not include the full pause. We will
3989 // investigate this in CR 7178365.
3990 double sample_end_time_sec = os::elapsedTime();
3991 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3992 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3993 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3994
3995 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3996 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3997
3998 MemoryService::track_memory_usage();
3999
4000 // In prepare_for_verify() below we'll need to scan the deferred
4001 // update buffers to bring the RSets up-to-date if
4002 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4003 // the update buffers we'll probably need to scan cards on the
4004 // regions we just allocated to (i.e., the GC alloc
4005 // regions). However, during the last GC we called
4006 // set_saved_mark() on all the GC alloc regions, so card
4007 // scanning might skip the [saved_mark_word()...top()] area of
4008 // those regions (i.e., the area we allocated objects into
4009 // during the last GC). But it shouldn't. Given that
4010 // saved_mark_word() is conditional on whether the GC time stamp
4011 // on the region is current or not, by incrementing the GC time
4012 // stamp here we invalidate all the GC time stamps on all the
4013 // regions and saved_mark_word() will simply return top() for
4014 // all the regions. This is a nicer way of ensuring this rather
4015 // than iterating over the regions and fixing them. In fact, the
4016 // GC time stamp increment here also ensures that
4017 // saved_mark_word() will return top() between pauses, i.e.,
4018 // during concurrent refinement. So we don't need the
4019 // is_gc_active() check to decided which top to use when
4020 // scanning cards (see CR 7039627).
4021 increment_gc_time_stamp();
4022
4023 verify_after_gc();
4024 check_bitmaps("GC End");
4025
4026 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4027 ref_processor_stw()->verify_no_references_recorded();
4028
4029 // CM reference discovery will be re-enabled if necessary.
4030 }
4031
4032 // We should do this after we potentially expand the heap so
4033 // that all the COMMIT events are generated before the end GC
4034 // event, and after we retire the GC alloc regions so that all
4035 // RETIRE events are generated before the end GC event.
4036 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4037
4038 #ifdef TRACESPINNING
4039 ParallelTaskTerminator::print_termination_counts();
4040 #endif
4041
4042 gc_epilogue(false);
4043 }
4044
4045 // Print the remainder of the GC log output.
4046 log_gc_footer(os::elapsedTime() - pause_start_sec);
4047
4048 // It is not yet to safe to tell the concurrent mark to
4049 // start as we have some optional output below. We don't want the
4050 // output from the concurrent mark thread interfering with this
4051 // logging output either.
4052
4053 _hrm.verify_optional();
4054 verify_region_sets_optional();
4055
4056 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4057 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4058
4059 print_heap_after_gc();
4060 trace_heap_after_gc(_gc_tracer_stw);
4061
4062 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4063 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4064 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4065 // before any GC notifications are raised.
4066 g1mm()->update_sizes();
4067
4068 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4069 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4070 _gc_timer_stw->register_gc_end();
4071 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4072 }
4073 // It should now be safe to tell the concurrent mark thread to start
4074 // without its logging output interfering with the logging output
4075 // that came from the pause.
4076
4077 if (should_start_conc_mark) {
4078 // CAUTION: after the doConcurrentMark() call below,
4079 // the concurrent marking thread(s) could be running
4080 // concurrently with us. Make sure that anything after
4081 // this point does not assume that we are the only GC thread
4082 // running. Note: of course, the actual marking work will
4083 // not start until the safepoint itself is released in
4084 // SuspendibleThreadSet::desynchronize().
4085 doConcurrentMark();
4086 }
4087
4088 return true;
4089 }
4090
4091 void G1CollectedHeap::remove_self_forwarding_pointers() {
4092 double remove_self_forwards_start = os::elapsedTime();
4093
4094 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4095 workers()->run_task(&rsfp_task);
4096
4097 // Now restore saved marks, if any.
4098 for (uint i = 0; i < ParallelGCThreads; i++) {
4099 OopAndMarkOopStack& cur = _preserved_objs[i];
4100 while (!cur.is_empty()) {
4101 OopAndMarkOop elem = cur.pop();
4102 elem.set_mark();
4103 }
4104 cur.clear(true);
4105 }
4106
4107 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4108 }
4109
4110 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4111 if (!_evacuation_failed) {
4112 _evacuation_failed = true;
4113 }
4114
4115 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4116
4117 // We want to call the "for_promotion_failure" version only in the
4118 // case of a promotion failure.
4119 if (m->must_be_preserved_for_promotion_failure(obj)) {
4120 OopAndMarkOop elem(obj, m);
4121 _preserved_objs[worker_id].push(elem);
4122 }
4123 }
4124
4125 class G1ParEvacuateFollowersClosure : public VoidClosure {
4126 private:
4127 double _start_term;
4128 double _term_time;
4129 size_t _term_attempts;
4130
4131 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4132 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4133 protected:
4134 G1CollectedHeap* _g1h;
4135 G1ParScanThreadState* _par_scan_state;
4136 RefToScanQueueSet* _queues;
4137 ParallelTaskTerminator* _terminator;
4138
4139 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4140 RefToScanQueueSet* queues() { return _queues; }
4141 ParallelTaskTerminator* terminator() { return _terminator; }
4142
4143 public:
4144 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4145 G1ParScanThreadState* par_scan_state,
4146 RefToScanQueueSet* queues,
4147 ParallelTaskTerminator* terminator)
4148 : _g1h(g1h), _par_scan_state(par_scan_state),
4149 _queues(queues), _terminator(terminator),
4150 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4151
4152 void do_void();
4153
4154 double term_time() const { return _term_time; }
4155 size_t term_attempts() const { return _term_attempts; }
4156
4157 private:
4158 inline bool offer_termination();
4159 };
4160
4161 bool G1ParEvacuateFollowersClosure::offer_termination() {
4162 G1ParScanThreadState* const pss = par_scan_state();
4163 start_term_time();
4164 const bool res = terminator()->offer_termination();
4165 end_term_time();
4166 return res;
4167 }
4168
4169 void G1ParEvacuateFollowersClosure::do_void() {
4170 G1ParScanThreadState* const pss = par_scan_state();
4171 pss->trim_queue();
4172 do {
4173 pss->steal_and_trim_queue(queues());
4174 } while (!offer_termination());
4175 }
4176
4177 class G1ParTask : public AbstractGangTask {
4178 protected:
4179 G1CollectedHeap* _g1h;
4180 G1ParScanThreadStateSet* _pss;
4181 RefToScanQueueSet* _queues;
4182 G1RootProcessor* _root_processor;
4183 ParallelTaskTerminator _terminator;
4184 uint _n_workers;
4185
4186 public:
4187 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4188 : AbstractGangTask("G1 collection"),
4189 _g1h(g1h),
4190 _pss(per_thread_states),
4191 _queues(task_queues),
4192 _root_processor(root_processor),
4193 _terminator(n_workers, _queues),
4194 _n_workers(n_workers)
4195 {}
4196
4197 void work(uint worker_id) {
4198 if (worker_id >= _n_workers) return; // no work needed this round
4199
4200 double start_sec = os::elapsedTime();
4201 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4202
4203 {
4204 ResourceMark rm;
4205 HandleMark hm;
4206
4207 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4208
4209 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4210 pss->set_ref_processor(rp);
4211
4212 double start_strong_roots_sec = os::elapsedTime();
4213
4214 _root_processor->evacuate_roots(pss->closures(), worker_id);
4215
4216 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4217
4218 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4219 // treating the nmethods visited to act as roots for concurrent marking.
4220 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4221 // objects copied by the current evacuation.
4222 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4223 pss->closures()->weak_codeblobs(),
4224 worker_id);
4225
4226 _pss->add_cards_scanned(worker_id, cards_scanned);
4227
4228 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4229
4230 double term_sec = 0.0;
4231 size_t evac_term_attempts = 0;
4232 {
4233 double start = os::elapsedTime();
4234 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4235 evac.do_void();
4236
4237 evac_term_attempts = evac.term_attempts();
4238 term_sec = evac.term_time();
4239 double elapsed_sec = os::elapsedTime() - start;
4240 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4241 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4242 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4243 }
4244
4245 assert(pss->queue_is_empty(), "should be empty");
4246
4247 if (PrintTerminationStats) {
4248 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4249 size_t lab_waste;
4250 size_t lab_undo_waste;
4251 pss->waste(lab_waste, lab_undo_waste);
4252 _g1h->print_termination_stats(gclog_or_tty,
4253 worker_id,
4254 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4255 strong_roots_sec * 1000.0, /* strong roots time */
4256 term_sec * 1000.0, /* evac term time */
4257 evac_term_attempts, /* evac term attempts */
4258 lab_waste, /* alloc buffer waste */
4259 lab_undo_waste /* undo waste */
4260 );
4261 }
4262
4263 // Close the inner scope so that the ResourceMark and HandleMark
4264 // destructors are executed here and are included as part of the
4265 // "GC Worker Time".
4266 }
4267 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4268 }
4269 };
4270
4271 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4272 st->print_raw_cr("GC Termination Stats");
4273 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4274 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4275 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4276 }
4277
4278 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4279 uint worker_id,
4280 double elapsed_ms,
4281 double strong_roots_ms,
4282 double term_ms,
4283 size_t term_attempts,
4284 size_t alloc_buffer_waste,
4285 size_t undo_waste) const {
4286 st->print_cr("%3d %9.2f %9.2f %6.2f "
4287 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4288 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4289 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4290 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4291 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4292 alloc_buffer_waste * HeapWordSize / K,
4293 undo_waste * HeapWordSize / K);
4294 }
4295
4296 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4297 private:
4298 BoolObjectClosure* _is_alive;
4299 int _initial_string_table_size;
4300 int _initial_symbol_table_size;
4301
4302 bool _process_strings;
4303 int _strings_processed;
4304 int _strings_removed;
4305
4306 bool _process_symbols;
4307 int _symbols_processed;
4308 int _symbols_removed;
4309
4310 public:
4311 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4312 AbstractGangTask("String/Symbol Unlinking"),
4313 _is_alive(is_alive),
4314 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4315 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4316
4317 _initial_string_table_size = StringTable::the_table()->table_size();
4318 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4319 if (process_strings) {
4320 StringTable::clear_parallel_claimed_index();
4321 }
4322 if (process_symbols) {
4323 SymbolTable::clear_parallel_claimed_index();
4324 }
4325 }
4326
4327 ~G1StringSymbolTableUnlinkTask() {
4328 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4329 "claim value %d after unlink less than initial string table size %d",
4330 StringTable::parallel_claimed_index(), _initial_string_table_size);
4331 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4332 "claim value %d after unlink less than initial symbol table size %d",
4333 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4334
4335 if (G1TraceStringSymbolTableScrubbing) {
4336 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4337 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4338 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4339 strings_processed(), strings_removed(),
4340 symbols_processed(), symbols_removed());
4341 }
4342 }
4343
4344 void work(uint worker_id) {
4345 int strings_processed = 0;
4346 int strings_removed = 0;
4347 int symbols_processed = 0;
4348 int symbols_removed = 0;
4349 if (_process_strings) {
4350 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4351 Atomic::add(strings_processed, &_strings_processed);
4352 Atomic::add(strings_removed, &_strings_removed);
4353 }
4354 if (_process_symbols) {
4355 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4356 Atomic::add(symbols_processed, &_symbols_processed);
4357 Atomic::add(symbols_removed, &_symbols_removed);
4358 }
4359 }
4360
4361 size_t strings_processed() const { return (size_t)_strings_processed; }
4362 size_t strings_removed() const { return (size_t)_strings_removed; }
4363
4364 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4365 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4366 };
4367
4368 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4369 private:
4370 static Monitor* _lock;
4371
4372 BoolObjectClosure* const _is_alive;
4373 const bool _unloading_occurred;
4374 const uint _num_workers;
4375
4376 // Variables used to claim nmethods.
4377 nmethod* _first_nmethod;
4378 volatile nmethod* _claimed_nmethod;
4379
4380 // The list of nmethods that need to be processed by the second pass.
4381 volatile nmethod* _postponed_list;
4382 volatile uint _num_entered_barrier;
4383
4384 public:
4385 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4386 _is_alive(is_alive),
4387 _unloading_occurred(unloading_occurred),
4388 _num_workers(num_workers),
4389 _first_nmethod(NULL),
4390 _claimed_nmethod(NULL),
4391 _postponed_list(NULL),
4392 _num_entered_barrier(0)
4393 {
4394 nmethod::increase_unloading_clock();
4395 // Get first alive nmethod
4396 NMethodIterator iter = NMethodIterator();
4397 if(iter.next_alive()) {
4398 _first_nmethod = iter.method();
4399 }
4400 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4401 }
4402
4403 ~G1CodeCacheUnloadingTask() {
4404 CodeCache::verify_clean_inline_caches();
4405
4406 CodeCache::set_needs_cache_clean(false);
4407 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4408
4409 CodeCache::verify_icholder_relocations();
4410 }
4411
4412 private:
4413 void add_to_postponed_list(nmethod* nm) {
4414 nmethod* old;
4415 do {
4416 old = (nmethod*)_postponed_list;
4417 nm->set_unloading_next(old);
4418 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4419 }
4420
4421 void clean_nmethod(nmethod* nm) {
4422 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4423
4424 if (postponed) {
4425 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4426 add_to_postponed_list(nm);
4427 }
4428
4429 // Mark that this thread has been cleaned/unloaded.
4430 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4431 nm->set_unloading_clock(nmethod::global_unloading_clock());
4432 }
4433
4434 void clean_nmethod_postponed(nmethod* nm) {
4435 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4436 }
4437
4438 static const int MaxClaimNmethods = 16;
4439
4440 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4441 nmethod* first;
4442 NMethodIterator last;
4443
4444 do {
4445 *num_claimed_nmethods = 0;
4446
4447 first = (nmethod*)_claimed_nmethod;
4448 last = NMethodIterator(first);
4449
4450 if (first != NULL) {
4451
4452 for (int i = 0; i < MaxClaimNmethods; i++) {
4453 if (!last.next_alive()) {
4454 break;
4455 }
4456 claimed_nmethods[i] = last.method();
4457 (*num_claimed_nmethods)++;
4458 }
4459 }
4460
4461 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4462 }
4463
4464 nmethod* claim_postponed_nmethod() {
4465 nmethod* claim;
4466 nmethod* next;
4467
4468 do {
4469 claim = (nmethod*)_postponed_list;
4470 if (claim == NULL) {
4471 return NULL;
4472 }
4473
4474 next = claim->unloading_next();
4475
4476 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4477
4478 return claim;
4479 }
4480
4481 public:
4482 // Mark that we're done with the first pass of nmethod cleaning.
4483 void barrier_mark(uint worker_id) {
4484 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4485 _num_entered_barrier++;
4486 if (_num_entered_barrier == _num_workers) {
4487 ml.notify_all();
4488 }
4489 }
4490
4491 // See if we have to wait for the other workers to
4492 // finish their first-pass nmethod cleaning work.
4493 void barrier_wait(uint worker_id) {
4494 if (_num_entered_barrier < _num_workers) {
4495 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4496 while (_num_entered_barrier < _num_workers) {
4497 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4498 }
4499 }
4500 }
4501
4502 // Cleaning and unloading of nmethods. Some work has to be postponed
4503 // to the second pass, when we know which nmethods survive.
4504 void work_first_pass(uint worker_id) {
4505 // The first nmethods is claimed by the first worker.
4506 if (worker_id == 0 && _first_nmethod != NULL) {
4507 clean_nmethod(_first_nmethod);
4508 _first_nmethod = NULL;
4509 }
4510
4511 int num_claimed_nmethods;
4512 nmethod* claimed_nmethods[MaxClaimNmethods];
4513
4514 while (true) {
4515 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4516
4517 if (num_claimed_nmethods == 0) {
4518 break;
4519 }
4520
4521 for (int i = 0; i < num_claimed_nmethods; i++) {
4522 clean_nmethod(claimed_nmethods[i]);
4523 }
4524 }
4525 }
4526
4527 void work_second_pass(uint worker_id) {
4528 nmethod* nm;
4529 // Take care of postponed nmethods.
4530 while ((nm = claim_postponed_nmethod()) != NULL) {
4531 clean_nmethod_postponed(nm);
4532 }
4533 }
4534 };
4535
4536 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4537
4538 class G1KlassCleaningTask : public StackObj {
4539 BoolObjectClosure* _is_alive;
4540 volatile jint _clean_klass_tree_claimed;
4541 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4542
4543 public:
4544 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4545 _is_alive(is_alive),
4546 _clean_klass_tree_claimed(0),
4547 _klass_iterator() {
4548 }
4549
4550 private:
4551 bool claim_clean_klass_tree_task() {
4552 if (_clean_klass_tree_claimed) {
4553 return false;
4554 }
4555
4556 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4557 }
4558
4559 InstanceKlass* claim_next_klass() {
4560 Klass* klass;
4561 do {
4562 klass =_klass_iterator.next_klass();
4563 } while (klass != NULL && !klass->is_instance_klass());
4564
4565 // this can be null so don't call InstanceKlass::cast
4566 return static_cast<InstanceKlass*>(klass);
4567 }
4568
4569 public:
4570
4571 void clean_klass(InstanceKlass* ik) {
4572 ik->clean_weak_instanceklass_links(_is_alive);
4573 }
4574
4575 void work() {
4576 ResourceMark rm;
4577
4578 // One worker will clean the subklass/sibling klass tree.
4579 if (claim_clean_klass_tree_task()) {
4580 Klass::clean_subklass_tree(_is_alive);
4581 }
4582
4583 // All workers will help cleaning the classes,
4584 InstanceKlass* klass;
4585 while ((klass = claim_next_klass()) != NULL) {
4586 clean_klass(klass);
4587 }
4588 }
4589 };
4590
4591 // To minimize the remark pause times, the tasks below are done in parallel.
4592 class G1ParallelCleaningTask : public AbstractGangTask {
4593 private:
4594 G1StringSymbolTableUnlinkTask _string_symbol_task;
4595 G1CodeCacheUnloadingTask _code_cache_task;
4596 G1KlassCleaningTask _klass_cleaning_task;
4597
4598 public:
4599 // The constructor is run in the VMThread.
4600 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4601 AbstractGangTask("Parallel Cleaning"),
4602 _string_symbol_task(is_alive, process_strings, process_symbols),
4603 _code_cache_task(num_workers, is_alive, unloading_occurred),
4604 _klass_cleaning_task(is_alive) {
4605 }
4606
4607 // The parallel work done by all worker threads.
4608 void work(uint worker_id) {
4609 // Do first pass of code cache cleaning.
4610 _code_cache_task.work_first_pass(worker_id);
4611
4612 // Let the threads mark that the first pass is done.
4613 _code_cache_task.barrier_mark(worker_id);
4614
4615 // Clean the Strings and Symbols.
4616 _string_symbol_task.work(worker_id);
4617
4618 // Wait for all workers to finish the first code cache cleaning pass.
4619 _code_cache_task.barrier_wait(worker_id);
4620
4621 // Do the second code cache cleaning work, which realize on
4622 // the liveness information gathered during the first pass.
4623 _code_cache_task.work_second_pass(worker_id);
4624
4625 // Clean all klasses that were not unloaded.
4626 _klass_cleaning_task.work();
4627 }
4628 };
4629
4630
4631 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4632 bool process_strings,
4633 bool process_symbols,
4634 bool class_unloading_occurred) {
4635 uint n_workers = workers()->active_workers();
4636
4637 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4638 n_workers, class_unloading_occurred);
4639 workers()->run_task(&g1_unlink_task);
4640 }
4641
4642 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4643 bool process_strings, bool process_symbols) {
4644 {
4645 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4646 workers()->run_task(&g1_unlink_task);
4647 }
4648
4649 if (G1StringDedup::is_enabled()) {
4650 G1StringDedup::unlink(is_alive);
4651 }
4652 }
4653
4654 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4655 private:
4656 DirtyCardQueueSet* _queue;
4657 public:
4658 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4659
4660 virtual void work(uint worker_id) {
4661 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4662 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4663
4664 RedirtyLoggedCardTableEntryClosure cl;
4665 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4666
4667 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4668 }
4669 };
4670
4671 void G1CollectedHeap::redirty_logged_cards() {
4672 double redirty_logged_cards_start = os::elapsedTime();
4673
4674 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4675 dirty_card_queue_set().reset_for_par_iteration();
4676 workers()->run_task(&redirty_task);
4677
4678 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4679 dcq.merge_bufferlists(&dirty_card_queue_set());
4680 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4681
4682 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4683 }
4684
4685 // Weak Reference Processing support
4686
4687 // An always "is_alive" closure that is used to preserve referents.
4688 // If the object is non-null then it's alive. Used in the preservation
4689 // of referent objects that are pointed to by reference objects
4690 // discovered by the CM ref processor.
4691 class G1AlwaysAliveClosure: public BoolObjectClosure {
4692 G1CollectedHeap* _g1;
4693 public:
4694 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4695 bool do_object_b(oop p) {
4696 if (p != NULL) {
4697 return true;
4698 }
4699 return false;
4700 }
4701 };
4702
4703 bool G1STWIsAliveClosure::do_object_b(oop p) {
4704 // An object is reachable if it is outside the collection set,
4705 // or is inside and copied.
4706 return !_g1->is_in_cset(p) || p->is_forwarded();
4707 }
4708
4709 // Non Copying Keep Alive closure
4710 class G1KeepAliveClosure: public OopClosure {
4711 G1CollectedHeap* _g1;
4712 public:
4713 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4714 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4715 void do_oop(oop* p) {
4716 oop obj = *p;
4717 assert(obj != NULL, "the caller should have filtered out NULL values");
4718
4719 const InCSetState cset_state = _g1->in_cset_state(obj);
4720 if (!cset_state.is_in_cset_or_humongous()) {
4721 return;
4722 }
4723 if (cset_state.is_in_cset()) {
4724 assert( obj->is_forwarded(), "invariant" );
4725 *p = obj->forwardee();
4726 } else {
4727 assert(!obj->is_forwarded(), "invariant" );
4728 assert(cset_state.is_humongous(),
4729 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4730 _g1->set_humongous_is_live(obj);
4731 }
4732 }
4733 };
4734
4735 // Copying Keep Alive closure - can be called from both
4736 // serial and parallel code as long as different worker
4737 // threads utilize different G1ParScanThreadState instances
4738 // and different queues.
4739
4740 class G1CopyingKeepAliveClosure: public OopClosure {
4741 G1CollectedHeap* _g1h;
4742 OopClosure* _copy_non_heap_obj_cl;
4743 G1ParScanThreadState* _par_scan_state;
4744
4745 public:
4746 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4747 OopClosure* non_heap_obj_cl,
4748 G1ParScanThreadState* pss):
4749 _g1h(g1h),
4750 _copy_non_heap_obj_cl(non_heap_obj_cl),
4751 _par_scan_state(pss)
4752 {}
4753
4754 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4755 virtual void do_oop( oop* p) { do_oop_work(p); }
4756
4757 template <class T> void do_oop_work(T* p) {
4758 oop obj = oopDesc::load_decode_heap_oop(p);
4759
4760 if (_g1h->is_in_cset_or_humongous(obj)) {
4761 // If the referent object has been forwarded (either copied
4762 // to a new location or to itself in the event of an
4763 // evacuation failure) then we need to update the reference
4764 // field and, if both reference and referent are in the G1
4765 // heap, update the RSet for the referent.
4766 //
4767 // If the referent has not been forwarded then we have to keep
4768 // it alive by policy. Therefore we have copy the referent.
4769 //
4770 // If the reference field is in the G1 heap then we can push
4771 // on the PSS queue. When the queue is drained (after each
4772 // phase of reference processing) the object and it's followers
4773 // will be copied, the reference field set to point to the
4774 // new location, and the RSet updated. Otherwise we need to
4775 // use the the non-heap or metadata closures directly to copy
4776 // the referent object and update the pointer, while avoiding
4777 // updating the RSet.
4778
4779 if (_g1h->is_in_g1_reserved(p)) {
4780 _par_scan_state->push_on_queue(p);
4781 } else {
4782 assert(!Metaspace::contains((const void*)p),
4783 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4784 _copy_non_heap_obj_cl->do_oop(p);
4785 }
4786 }
4787 }
4788 };
4789
4790 // Serial drain queue closure. Called as the 'complete_gc'
4791 // closure for each discovered list in some of the
4792 // reference processing phases.
4793
4794 class G1STWDrainQueueClosure: public VoidClosure {
4795 protected:
4796 G1CollectedHeap* _g1h;
4797 G1ParScanThreadState* _par_scan_state;
4798
4799 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4800
4801 public:
4802 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4803 _g1h(g1h),
4804 _par_scan_state(pss)
4805 { }
4806
4807 void do_void() {
4808 G1ParScanThreadState* const pss = par_scan_state();
4809 pss->trim_queue();
4810 }
4811 };
4812
4813 // Parallel Reference Processing closures
4814
4815 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4816 // processing during G1 evacuation pauses.
4817
4818 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4819 private:
4820 G1CollectedHeap* _g1h;
4821 G1ParScanThreadStateSet* _pss;
4822 RefToScanQueueSet* _queues;
4823 WorkGang* _workers;
4824 uint _active_workers;
4825
4826 public:
4827 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4828 G1ParScanThreadStateSet* per_thread_states,
4829 WorkGang* workers,
4830 RefToScanQueueSet *task_queues,
4831 uint n_workers) :
4832 _g1h(g1h),
4833 _pss(per_thread_states),
4834 _queues(task_queues),
4835 _workers(workers),
4836 _active_workers(n_workers)
4837 {
4838 assert(n_workers > 0, "shouldn't call this otherwise");
4839 }
4840
4841 // Executes the given task using concurrent marking worker threads.
4842 virtual void execute(ProcessTask& task);
4843 virtual void execute(EnqueueTask& task);
4844 };
4845
4846 // Gang task for possibly parallel reference processing
4847
4848 class G1STWRefProcTaskProxy: public AbstractGangTask {
4849 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4850 ProcessTask& _proc_task;
4851 G1CollectedHeap* _g1h;
4852 G1ParScanThreadStateSet* _pss;
4853 RefToScanQueueSet* _task_queues;
4854 ParallelTaskTerminator* _terminator;
4855
4856 public:
4857 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4858 G1CollectedHeap* g1h,
4859 G1ParScanThreadStateSet* per_thread_states,
4860 RefToScanQueueSet *task_queues,
4861 ParallelTaskTerminator* terminator) :
4862 AbstractGangTask("Process reference objects in parallel"),
4863 _proc_task(proc_task),
4864 _g1h(g1h),
4865 _pss(per_thread_states),
4866 _task_queues(task_queues),
4867 _terminator(terminator)
4868 {}
4869
4870 virtual void work(uint worker_id) {
4871 // The reference processing task executed by a single worker.
4872 ResourceMark rm;
4873 HandleMark hm;
4874
4875 G1STWIsAliveClosure is_alive(_g1h);
4876
4877 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4878 pss->set_ref_processor(NULL);
4879
4880 // Keep alive closure.
4881 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4882
4883 // Complete GC closure
4884 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4885
4886 // Call the reference processing task's work routine.
4887 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4888
4889 // Note we cannot assert that the refs array is empty here as not all
4890 // of the processing tasks (specifically phase2 - pp2_work) execute
4891 // the complete_gc closure (which ordinarily would drain the queue) so
4892 // the queue may not be empty.
4893 }
4894 };
4895
4896 // Driver routine for parallel reference processing.
4897 // Creates an instance of the ref processing gang
4898 // task and has the worker threads execute it.
4899 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4900 assert(_workers != NULL, "Need parallel worker threads.");
4901
4902 ParallelTaskTerminator terminator(_active_workers, _queues);
4903 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4904
4905 _workers->run_task(&proc_task_proxy);
4906 }
4907
4908 // Gang task for parallel reference enqueueing.
4909
4910 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4911 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4912 EnqueueTask& _enq_task;
4913
4914 public:
4915 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4916 AbstractGangTask("Enqueue reference objects in parallel"),
4917 _enq_task(enq_task)
4918 { }
4919
4920 virtual void work(uint worker_id) {
4921 _enq_task.work(worker_id);
4922 }
4923 };
4924
4925 // Driver routine for parallel reference enqueueing.
4926 // Creates an instance of the ref enqueueing gang
4927 // task and has the worker threads execute it.
4928
4929 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4930 assert(_workers != NULL, "Need parallel worker threads.");
4931
4932 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4933
4934 _workers->run_task(&enq_task_proxy);
4935 }
4936
4937 // End of weak reference support closures
4938
4939 // Abstract task used to preserve (i.e. copy) any referent objects
4940 // that are in the collection set and are pointed to by reference
4941 // objects discovered by the CM ref processor.
4942
4943 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4944 protected:
4945 G1CollectedHeap* _g1h;
4946 G1ParScanThreadStateSet* _pss;
4947 RefToScanQueueSet* _queues;
4948 ParallelTaskTerminator _terminator;
4949 uint _n_workers;
4950
4951 public:
4952 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4953 AbstractGangTask("ParPreserveCMReferents"),
4954 _g1h(g1h),
4955 _pss(per_thread_states),
4956 _queues(task_queues),
4957 _terminator(workers, _queues),
4958 _n_workers(workers)
4959 { }
4960
4961 void work(uint worker_id) {
4962 ResourceMark rm;
4963 HandleMark hm;
4964
4965 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4966 pss->set_ref_processor(NULL);
4967 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4968
4969 // Is alive closure
4970 G1AlwaysAliveClosure always_alive(_g1h);
4971
4972 // Copying keep alive closure. Applied to referent objects that need
4973 // to be copied.
4974 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4975
4976 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4977
4978 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4979 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4980
4981 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4982 // So this must be true - but assert just in case someone decides to
4983 // change the worker ids.
4984 assert(worker_id < limit, "sanity");
4985 assert(!rp->discovery_is_atomic(), "check this code");
4986
4987 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4988 for (uint idx = worker_id; idx < limit; idx += stride) {
4989 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4990
4991 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4992 while (iter.has_next()) {
4993 // Since discovery is not atomic for the CM ref processor, we
4994 // can see some null referent objects.
4995 iter.load_ptrs(DEBUG_ONLY(true));
4996 oop ref = iter.obj();
4997
4998 // This will filter nulls.
4999 if (iter.is_referent_alive()) {
5000 iter.make_referent_alive();
5001 }
5002 iter.move_to_next();
5003 }
5004 }
5005
5006 // Drain the queue - which may cause stealing
5007 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5008 drain_queue.do_void();
5009 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5010 assert(pss->queue_is_empty(), "should be");
5011 }
5012 };
5013
5014 // Weak Reference processing during an evacuation pause (part 1).
5015 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5016 double ref_proc_start = os::elapsedTime();
5017
5018 ReferenceProcessor* rp = _ref_processor_stw;
5019 assert(rp->discovery_enabled(), "should have been enabled");
5020
5021 // Any reference objects, in the collection set, that were 'discovered'
5022 // by the CM ref processor should have already been copied (either by
5023 // applying the external root copy closure to the discovered lists, or
5024 // by following an RSet entry).
5025 //
5026 // But some of the referents, that are in the collection set, that these
5027 // reference objects point to may not have been copied: the STW ref
5028 // processor would have seen that the reference object had already
5029 // been 'discovered' and would have skipped discovering the reference,
5030 // but would not have treated the reference object as a regular oop.
5031 // As a result the copy closure would not have been applied to the
5032 // referent object.
5033 //
5034 // We need to explicitly copy these referent objects - the references
5035 // will be processed at the end of remarking.
5036 //
5037 // We also need to do this copying before we process the reference
5038 // objects discovered by the STW ref processor in case one of these
5039 // referents points to another object which is also referenced by an
5040 // object discovered by the STW ref processor.
5041
5042 uint no_of_gc_workers = workers()->active_workers();
5043
5044 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5045 per_thread_states,
5046 no_of_gc_workers,
5047 _task_queues);
5048
5049 workers()->run_task(&keep_cm_referents);
5050
5051 // Closure to test whether a referent is alive.
5052 G1STWIsAliveClosure is_alive(this);
5053
5054 // Even when parallel reference processing is enabled, the processing
5055 // of JNI refs is serial and performed serially by the current thread
5056 // rather than by a worker. The following PSS will be used for processing
5057 // JNI refs.
5058
5059 // Use only a single queue for this PSS.
5060 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5061 pss->set_ref_processor(NULL);
5062 assert(pss->queue_is_empty(), "pre-condition");
5063
5064 // Keep alive closure.
5065 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5066
5067 // Serial Complete GC closure
5068 G1STWDrainQueueClosure drain_queue(this, pss);
5069
5070 // Setup the soft refs policy...
5071 rp->setup_policy(false);
5072
5073 ReferenceProcessorStats stats;
5074 if (!rp->processing_is_mt()) {
5075 // Serial reference processing...
5076 stats = rp->process_discovered_references(&is_alive,
5077 &keep_alive,
5078 &drain_queue,
5079 NULL,
5080 _gc_timer_stw);
5081 } else {
5082 // Parallel reference processing
5083 assert(rp->num_q() == no_of_gc_workers, "sanity");
5084 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5085
5086 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5087 stats = rp->process_discovered_references(&is_alive,
5088 &keep_alive,
5089 &drain_queue,
5090 &par_task_executor,
5091 _gc_timer_stw);
5092 }
5093
5094 _gc_tracer_stw->report_gc_reference_stats(stats);
5095
5096 // We have completed copying any necessary live referent objects.
5097 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5098
5099 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5100 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5101 }
5102
5103 // Weak Reference processing during an evacuation pause (part 2).
5104 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5105 double ref_enq_start = os::elapsedTime();
5106
5107 ReferenceProcessor* rp = _ref_processor_stw;
5108 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5109
5110 // Now enqueue any remaining on the discovered lists on to
5111 // the pending list.
5112 if (!rp->processing_is_mt()) {
5113 // Serial reference processing...
5114 rp->enqueue_discovered_references();
5115 } else {
5116 // Parallel reference enqueueing
5117
5118 uint n_workers = workers()->active_workers();
5119
5120 assert(rp->num_q() == n_workers, "sanity");
5121 assert(n_workers <= rp->max_num_q(), "sanity");
5122
5123 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5124 rp->enqueue_discovered_references(&par_task_executor);
5125 }
5126
5127 rp->verify_no_references_recorded();
5128 assert(!rp->discovery_enabled(), "should have been disabled");
5129
5130 // FIXME
5131 // CM's reference processing also cleans up the string and symbol tables.
5132 // Should we do that here also? We could, but it is a serial operation
5133 // and could significantly increase the pause time.
5134
5135 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5136 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5137 }
5138
5139 void G1CollectedHeap::pre_evacuate_collection_set() {
5140 _expand_heap_after_alloc_failure = true;
5141 _evacuation_failed = false;
5142
5143 // Disable the hot card cache.
5144 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5145 hot_card_cache->reset_hot_cache_claimed_index();
5146 hot_card_cache->set_use_cache(false);
5147
5148 }
5149
5150 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5151 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5152
5153 // Should G1EvacuationFailureALot be in effect for this GC?
5154 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5155
5156 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5157 double start_par_time_sec = os::elapsedTime();
5158 double end_par_time_sec;
5159
5160 {
5161 const uint n_workers = workers()->active_workers();
5162 G1RootProcessor root_processor(this, n_workers);
5163 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5164 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5165 if (collector_state()->during_initial_mark_pause()) {
5166 ClassLoaderDataGraph::clear_claimed_marks();
5167 }
5168
5169 // The individual threads will set their evac-failure closures.
5170 if (PrintTerminationStats) {
5171 print_termination_stats_hdr(gclog_or_tty);
5172 }
5173
5174 workers()->run_task(&g1_par_task);
5175 end_par_time_sec = os::elapsedTime();
5176
5177 // Closing the inner scope will execute the destructor
5178 // for the G1RootProcessor object. We record the current
5179 // elapsed time before closing the scope so that time
5180 // taken for the destructor is NOT included in the
5181 // reported parallel time.
5182 }
5183
5184 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5185
5186 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5187 phase_times->record_par_time(par_time_ms);
5188
5189 double code_root_fixup_time_ms =
5190 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5191 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5192
5193 // Process any discovered reference objects - we have
5194 // to do this _before_ we retire the GC alloc regions
5195 // as we may have to copy some 'reachable' referent
5196 // objects (and their reachable sub-graphs) that were
5197 // not copied during the pause.
5198 process_discovered_references(per_thread_states);
5199
5200 if (G1StringDedup::is_enabled()) {
5201 double fixup_start = os::elapsedTime();
5202
5203 G1STWIsAliveClosure is_alive(this);
5204 G1KeepAliveClosure keep_alive(this);
5205 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5206
5207 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5208 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5209 }
5210
5211 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5212
5213 if (evacuation_failed()) {
5214 remove_self_forwarding_pointers();
5215
5216 // Reset the G1EvacuationFailureALot counters and flags
5217 // Note: the values are reset only when an actual
5218 // evacuation failure occurs.
5219 NOT_PRODUCT(reset_evacuation_should_fail();)
5220 }
5221
5222 // Enqueue any remaining references remaining on the STW
5223 // reference processor's discovered lists. We need to do
5224 // this after the card table is cleaned (and verified) as
5225 // the act of enqueueing entries on to the pending list
5226 // will log these updates (and dirty their associated
5227 // cards). We need these updates logged to update any
5228 // RSets.
5229 enqueue_discovered_references(per_thread_states);
5230 }
5231
5232 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5233 _allocator->release_gc_alloc_regions(evacuation_info);
5234
5235 per_thread_states->flush();
5236
5237 record_obj_copy_mem_stats();
5238
5239 // Reset and re-enable the hot card cache.
5240 // Note the counts for the cards in the regions in the
5241 // collection set are reset when the collection set is freed.
5242 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5243 hot_card_cache->reset_hot_cache();
5244 hot_card_cache->set_use_cache(true);
5245
5246 purge_code_root_memory();
5247
5248 redirty_logged_cards();
5249 #if defined(COMPILER2) || INCLUDE_JVMCI
5250 DerivedPointerTable::update_pointers();
5251 #endif
5252 }
5253
5254 void G1CollectedHeap::record_obj_copy_mem_stats() {
5255 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5256 create_g1_evac_summary(&_old_evac_stats));
5257 }
5258
5259 void G1CollectedHeap::free_region(HeapRegion* hr,
5260 FreeRegionList* free_list,
5261 bool par,
5262 bool locked) {
5263 assert(!hr->is_free(), "the region should not be free");
5264 assert(!hr->is_empty(), "the region should not be empty");
5265 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5266 assert(free_list != NULL, "pre-condition");
5267
5268 if (G1VerifyBitmaps) {
5269 MemRegion mr(hr->bottom(), hr->end());
5270 concurrent_mark()->clearRangePrevBitmap(mr);
5271 }
5272
5273 // Clear the card counts for this region.
5274 // Note: we only need to do this if the region is not young
5275 // (since we don't refine cards in young regions).
5276 if (!hr->is_young()) {
5277 _cg1r->hot_card_cache()->reset_card_counts(hr);
5278 }
5279 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5280 free_list->add_ordered(hr);
5281 }
5282
5283 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5284 FreeRegionList* free_list,
5285 bool par) {
5286 assert(hr->is_humongous(), "this is only for humongous regions");
5287 assert(free_list != NULL, "pre-condition");
5288 hr->clear_humongous();
5289 free_region(hr, free_list, par);
5290 }
5291
5292 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5293 const HeapRegionSetCount& humongous_regions_removed) {
5294 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5295 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5296 _old_set.bulk_remove(old_regions_removed);
5297 _humongous_set.bulk_remove(humongous_regions_removed);
5298 }
5299
5300 }
5301
5302 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5303 assert(list != NULL, "list can't be null");
5304 if (!list->is_empty()) {
5305 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5306 _hrm.insert_list_into_free_list(list);
5307 }
5308 }
5309
5310 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5311 decrease_used(bytes);
5312 }
5313
5314 class G1ParCleanupCTTask : public AbstractGangTask {
5315 G1SATBCardTableModRefBS* _ct_bs;
5316 G1CollectedHeap* _g1h;
5317 HeapRegion* volatile _su_head;
5318 public:
5319 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5320 G1CollectedHeap* g1h) :
5321 AbstractGangTask("G1 Par Cleanup CT Task"),
5322 _ct_bs(ct_bs), _g1h(g1h) { }
5323
5324 void work(uint worker_id) {
5325 HeapRegion* r;
5326 while (r = _g1h->pop_dirty_cards_region()) {
5327 clear_cards(r);
5328 }
5329 }
5330
5331 void clear_cards(HeapRegion* r) {
5332 // Cards of the survivors should have already been dirtied.
5333 if (!r->is_survivor()) {
5334 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5335 }
5336 }
5337 };
5338
5339 #ifndef PRODUCT
5340 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5341 G1CollectedHeap* _g1h;
5342 G1SATBCardTableModRefBS* _ct_bs;
5343 public:
5344 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5345 : _g1h(g1h), _ct_bs(ct_bs) { }
5346 virtual bool doHeapRegion(HeapRegion* r) {
5347 if (r->is_survivor()) {
5348 _g1h->verify_dirty_region(r);
5349 } else {
5350 _g1h->verify_not_dirty_region(r);
5351 }
5352 return false;
5353 }
5354 };
5355
5356 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5357 // All of the region should be clean.
5358 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5359 MemRegion mr(hr->bottom(), hr->end());
5360 ct_bs->verify_not_dirty_region(mr);
5361 }
5362
5363 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5364 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5365 // dirty allocated blocks as they allocate them. The thread that
5366 // retires each region and replaces it with a new one will do a
5367 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5368 // not dirty that area (one less thing to have to do while holding
5369 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5370 // is dirty.
5371 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5372 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5373 if (hr->is_young()) {
5374 ct_bs->verify_g1_young_region(mr);
5375 } else {
5376 ct_bs->verify_dirty_region(mr);
5377 }
5378 }
5379
5380 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5381 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5382 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5383 verify_dirty_region(hr);
5384 }
5385 }
5386
5387 void G1CollectedHeap::verify_dirty_young_regions() {
5388 verify_dirty_young_list(_young_list->first_region());
5389 }
5390
5391 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5392 HeapWord* tams, HeapWord* end) {
5393 guarantee(tams <= end,
5394 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5395 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5396 if (result < end) {
5397 gclog_or_tty->cr();
5398 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5399 bitmap_name, p2i(result));
5400 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5401 bitmap_name, p2i(tams), p2i(end));
5402 return false;
5403 }
5404 return true;
5405 }
5406
5407 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5408 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5409 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5410
5411 HeapWord* bottom = hr->bottom();
5412 HeapWord* ptams = hr->prev_top_at_mark_start();
5413 HeapWord* ntams = hr->next_top_at_mark_start();
5414 HeapWord* end = hr->end();
5415
5416 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5417
5418 bool res_n = true;
5419 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5420 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5421 // if we happen to be in that state.
5422 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5423 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5424 }
5425 if (!res_p || !res_n) {
5426 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5427 HR_FORMAT_PARAMS(hr));
5428 gclog_or_tty->print_cr("#### Caller: %s", caller);
5429 return false;
5430 }
5431 return true;
5432 }
5433
5434 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5435 if (!G1VerifyBitmaps) return;
5436
5437 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5438 }
5439
5440 class G1VerifyBitmapClosure : public HeapRegionClosure {
5441 private:
5442 const char* _caller;
5443 G1CollectedHeap* _g1h;
5444 bool _failures;
5445
5446 public:
5447 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5448 _caller(caller), _g1h(g1h), _failures(false) { }
5449
5450 bool failures() { return _failures; }
5451
5452 virtual bool doHeapRegion(HeapRegion* hr) {
5453 bool result = _g1h->verify_bitmaps(_caller, hr);
5454 if (!result) {
5455 _failures = true;
5456 }
5457 return false;
5458 }
5459 };
5460
5461 void G1CollectedHeap::check_bitmaps(const char* caller) {
5462 if (!G1VerifyBitmaps) return;
5463
5464 G1VerifyBitmapClosure cl(caller, this);
5465 heap_region_iterate(&cl);
5466 guarantee(!cl.failures(), "bitmap verification");
5467 }
5468
5469 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5470 private:
5471 bool _failures;
5472 public:
5473 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5474
5475 virtual bool doHeapRegion(HeapRegion* hr) {
5476 uint i = hr->hrm_index();
5477 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5478 if (hr->is_humongous()) {
5479 if (hr->in_collection_set()) {
5480 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5481 _failures = true;
5482 return true;
5483 }
5484 if (cset_state.is_in_cset()) {
5485 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5486 _failures = true;
5487 return true;
5488 }
5489 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5490 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5491 _failures = true;
5492 return true;
5493 }
5494 } else {
5495 if (cset_state.is_humongous()) {
5496 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5497 _failures = true;
5498 return true;
5499 }
5500 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5501 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5502 hr->in_collection_set(), cset_state.value(), i);
5503 _failures = true;
5504 return true;
5505 }
5506 if (cset_state.is_in_cset()) {
5507 if (hr->is_young() != (cset_state.is_young())) {
5508 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5509 hr->is_young(), cset_state.value(), i);
5510 _failures = true;
5511 return true;
5512 }
5513 if (hr->is_old() != (cset_state.is_old())) {
5514 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5515 hr->is_old(), cset_state.value(), i);
5516 _failures = true;
5517 return true;
5518 }
5519 }
5520 }
5521 return false;
5522 }
5523
5524 bool failures() const { return _failures; }
5525 };
5526
5527 bool G1CollectedHeap::check_cset_fast_test() {
5528 G1CheckCSetFastTableClosure cl;
5529 _hrm.iterate(&cl);
5530 return !cl.failures();
5531 }
5532 #endif // PRODUCT
5533
5534 void G1CollectedHeap::cleanUpCardTable() {
5535 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5536 double start = os::elapsedTime();
5537
5538 {
5539 // Iterate over the dirty cards region list.
5540 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5541
5542 workers()->run_task(&cleanup_task);
5543 #ifndef PRODUCT
5544 if (G1VerifyCTCleanup || VerifyAfterGC) {
5545 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5546 heap_region_iterate(&cleanup_verifier);
5547 }
5548 #endif
5549 }
5550
5551 double elapsed = os::elapsedTime() - start;
5552 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5553 }
5554
5555 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5556 size_t pre_used = 0;
5557 FreeRegionList local_free_list("Local List for CSet Freeing");
5558
5559 double young_time_ms = 0.0;
5560 double non_young_time_ms = 0.0;
5561
5562 // Since the collection set is a superset of the the young list,
5563 // all we need to do to clear the young list is clear its
5564 // head and length, and unlink any young regions in the code below
5565 _young_list->clear();
5566
5567 G1CollectorPolicy* policy = g1_policy();
5568
5569 double start_sec = os::elapsedTime();
5570 bool non_young = true;
5571
5572 HeapRegion* cur = cs_head;
5573 int age_bound = -1;
5574 size_t rs_lengths = 0;
5575
5576 while (cur != NULL) {
5577 assert(!is_on_master_free_list(cur), "sanity");
5578 if (non_young) {
5579 if (cur->is_young()) {
5580 double end_sec = os::elapsedTime();
5581 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5582 non_young_time_ms += elapsed_ms;
5583
5584 start_sec = os::elapsedTime();
5585 non_young = false;
5586 }
5587 } else {
5588 if (!cur->is_young()) {
5589 double end_sec = os::elapsedTime();
5590 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5591 young_time_ms += elapsed_ms;
5592
5593 start_sec = os::elapsedTime();
5594 non_young = true;
5595 }
5596 }
5597
5598 rs_lengths += cur->rem_set()->occupied_locked();
5599
5600 HeapRegion* next = cur->next_in_collection_set();
5601 assert(cur->in_collection_set(), "bad CS");
5602 cur->set_next_in_collection_set(NULL);
5603 clear_in_cset(cur);
5604
5605 if (cur->is_young()) {
5606 int index = cur->young_index_in_cset();
5607 assert(index != -1, "invariant");
5608 assert((uint) index < policy->young_cset_region_length(), "invariant");
5609 size_t words_survived = surviving_young_words[index];
5610 cur->record_surv_words_in_group(words_survived);
5611
5612 // At this point the we have 'popped' cur from the collection set
5613 // (linked via next_in_collection_set()) but it is still in the
5614 // young list (linked via next_young_region()). Clear the
5615 // _next_young_region field.
5616 cur->set_next_young_region(NULL);
5617 } else {
5618 int index = cur->young_index_in_cset();
5619 assert(index == -1, "invariant");
5620 }
5621
5622 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5623 (!cur->is_young() && cur->young_index_in_cset() == -1),
5624 "invariant" );
5625
5626 if (!cur->evacuation_failed()) {
5627 MemRegion used_mr = cur->used_region();
5628
5629 // And the region is empty.
5630 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5631 pre_used += cur->used();
5632 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5633 } else {
5634 cur->uninstall_surv_rate_group();
5635 if (cur->is_young()) {
5636 cur->set_young_index_in_cset(-1);
5637 }
5638 cur->set_evacuation_failed(false);
5639 // The region is now considered to be old.
5640 cur->set_old();
5641 // Do some allocation statistics accounting. Regions that failed evacuation
5642 // are always made old, so there is no need to update anything in the young
5643 // gen statistics, but we need to update old gen statistics.
5644 size_t used_words = cur->marked_bytes() / HeapWordSize;
5645 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5646 _old_set.add(cur);
5647 evacuation_info.increment_collectionset_used_after(cur->used());
5648 }
5649 cur = next;
5650 }
5651
5652 evacuation_info.set_regions_freed(local_free_list.length());
5653 policy->record_max_rs_lengths(rs_lengths);
5654 policy->cset_regions_freed();
5655
5656 double end_sec = os::elapsedTime();
5657 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5658
5659 if (non_young) {
5660 non_young_time_ms += elapsed_ms;
5661 } else {
5662 young_time_ms += elapsed_ms;
5663 }
5664
5665 prepend_to_freelist(&local_free_list);
5666 decrement_summary_bytes(pre_used);
5667 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5668 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5669 }
5670
5671 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5672 private:
5673 FreeRegionList* _free_region_list;
5674 HeapRegionSet* _proxy_set;
5675 HeapRegionSetCount _humongous_regions_removed;
5676 size_t _freed_bytes;
5677 public:
5678
5679 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5680 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5681 }
5682
5683 virtual bool doHeapRegion(HeapRegion* r) {
5684 if (!r->is_starts_humongous()) {
5685 return false;
5686 }
5687
5688 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5689
5690 oop obj = (oop)r->bottom();
5691 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5692
5693 // The following checks whether the humongous object is live are sufficient.
5694 // The main additional check (in addition to having a reference from the roots
5695 // or the young gen) is whether the humongous object has a remembered set entry.
5696 //
5697 // A humongous object cannot be live if there is no remembered set for it
5698 // because:
5699 // - there can be no references from within humongous starts regions referencing
5700 // the object because we never allocate other objects into them.
5701 // (I.e. there are no intra-region references that may be missed by the
5702 // remembered set)
5703 // - as soon there is a remembered set entry to the humongous starts region
5704 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5705 // until the end of a concurrent mark.
5706 //
5707 // It is not required to check whether the object has been found dead by marking
5708 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5709 // all objects allocated during that time are considered live.
5710 // SATB marking is even more conservative than the remembered set.
5711 // So if at this point in the collection there is no remembered set entry,
5712 // nobody has a reference to it.
5713 // At the start of collection we flush all refinement logs, and remembered sets
5714 // are completely up-to-date wrt to references to the humongous object.
5715 //
5716 // Other implementation considerations:
5717 // - never consider object arrays at this time because they would pose
5718 // considerable effort for cleaning up the the remembered sets. This is
5719 // required because stale remembered sets might reference locations that
5720 // are currently allocated into.
5721 uint region_idx = r->hrm_index();
5722 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5723 !r->rem_set()->is_empty()) {
5724
5725 if (G1TraceEagerReclaimHumongousObjects) {
5726 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",
5727 region_idx,
5728 (size_t)obj->size() * HeapWordSize,
5729 p2i(r->bottom()),
5730 r->rem_set()->occupied(),
5731 r->rem_set()->strong_code_roots_list_length(),
5732 next_bitmap->isMarked(r->bottom()),
5733 g1h->is_humongous_reclaim_candidate(region_idx),
5734 obj->is_typeArray()
5735 );
5736 }
5737
5738 return false;
5739 }
5740
5741 guarantee(obj->is_typeArray(),
5742 "Only eagerly reclaiming type arrays is supported, but the object "
5743 PTR_FORMAT " is not.", p2i(r->bottom()));
5744
5745 if (G1TraceEagerReclaimHumongousObjects) {
5746 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",
5747 region_idx,
5748 (size_t)obj->size() * HeapWordSize,
5749 p2i(r->bottom()),
5750 r->rem_set()->occupied(),
5751 r->rem_set()->strong_code_roots_list_length(),
5752 next_bitmap->isMarked(r->bottom()),
5753 g1h->is_humongous_reclaim_candidate(region_idx),
5754 obj->is_typeArray()
5755 );
5756 }
5757 // Need to clear mark bit of the humongous object if already set.
5758 if (next_bitmap->isMarked(r->bottom())) {
5759 next_bitmap->clear(r->bottom());
5760 }
5761 do {
5762 HeapRegion* next = g1h->next_humongous_region(r);
5763 _freed_bytes += r->used();
5764 r->set_containing_set(NULL);
5765 _humongous_regions_removed.increment(1u, r->capacity());
5766 g1h->free_humongous_region(r, _free_region_list, false);
5767 r = next;
5768 } while (r != NULL);
5769
5770 return false;
5771 }
5772
5773 HeapRegionSetCount& humongous_free_count() {
5774 return _humongous_regions_removed;
5775 }
5776
5777 size_t bytes_freed() const {
5778 return _freed_bytes;
5779 }
5780
5781 size_t humongous_reclaimed() const {
5782 return _humongous_regions_removed.length();
5783 }
5784 };
5785
5786 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5787 assert_at_safepoint(true);
5788
5789 if (!G1EagerReclaimHumongousObjects ||
5790 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5791 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5792 return;
5793 }
5794
5795 double start_time = os::elapsedTime();
5796
5797 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5798
5799 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5800 heap_region_iterate(&cl);
5801
5802 HeapRegionSetCount empty_set;
5803 remove_from_old_sets(empty_set, cl.humongous_free_count());
5804
5805 G1HRPrinter* hrp = hr_printer();
5806 if (hrp->is_active()) {
5807 FreeRegionListIterator iter(&local_cleanup_list);
5808 while (iter.more_available()) {
5809 HeapRegion* hr = iter.get_next();
5810 hrp->cleanup(hr);
5811 }
5812 }
5813
5814 prepend_to_freelist(&local_cleanup_list);
5815 decrement_summary_bytes(cl.bytes_freed());
5816
5817 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5818 cl.humongous_reclaimed());
5819 }
5820
5821 // This routine is similar to the above but does not record
5822 // any policy statistics or update free lists; we are abandoning
5823 // the current incremental collection set in preparation of a
5824 // full collection. After the full GC we will start to build up
5825 // the incremental collection set again.
5826 // This is only called when we're doing a full collection
5827 // and is immediately followed by the tearing down of the young list.
5828
5829 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5830 HeapRegion* cur = cs_head;
5831
5832 while (cur != NULL) {
5833 HeapRegion* next = cur->next_in_collection_set();
5834 assert(cur->in_collection_set(), "bad CS");
5835 cur->set_next_in_collection_set(NULL);
5836 clear_in_cset(cur);
5837 cur->set_young_index_in_cset(-1);
5838 cur = next;
5839 }
5840 }
5841
5842 void G1CollectedHeap::set_free_regions_coming() {
5843 if (G1ConcRegionFreeingVerbose) {
5844 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5845 "setting free regions coming");
5846 }
5847
5848 assert(!free_regions_coming(), "pre-condition");
5849 _free_regions_coming = true;
5850 }
5851
5852 void G1CollectedHeap::reset_free_regions_coming() {
5853 assert(free_regions_coming(), "pre-condition");
5854
5855 {
5856 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5857 _free_regions_coming = false;
5858 SecondaryFreeList_lock->notify_all();
5859 }
5860
5861 if (G1ConcRegionFreeingVerbose) {
5862 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5863 "reset free regions coming");
5864 }
5865 }
5866
5867 void G1CollectedHeap::wait_while_free_regions_coming() {
5868 // Most of the time we won't have to wait, so let's do a quick test
5869 // first before we take the lock.
5870 if (!free_regions_coming()) {
5871 return;
5872 }
5873
5874 if (G1ConcRegionFreeingVerbose) {
5875 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5876 "waiting for free regions");
5877 }
5878
5879 {
5880 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5881 while (free_regions_coming()) {
5882 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5883 }
5884 }
5885
5886 if (G1ConcRegionFreeingVerbose) {
5887 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5888 "done waiting for free regions");
5889 }
5890 }
5891
5892 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5893 return _allocator->is_retained_old_region(hr);
5894 }
5895
5896 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5897 _young_list->push_region(hr);
5898 }
5899
5900 class NoYoungRegionsClosure: public HeapRegionClosure {
5901 private:
5902 bool _success;
5903 public:
5904 NoYoungRegionsClosure() : _success(true) { }
5905 bool doHeapRegion(HeapRegion* r) {
5906 if (r->is_young()) {
5907 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5908 p2i(r->bottom()), p2i(r->end()));
5909 _success = false;
5910 }
5911 return false;
5912 }
5913 bool success() { return _success; }
5914 };
5915
5916 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5917 bool ret = _young_list->check_list_empty(check_sample);
5918
5919 if (check_heap) {
5920 NoYoungRegionsClosure closure;
5921 heap_region_iterate(&closure);
5922 ret = ret && closure.success();
5923 }
5924
5925 return ret;
5926 }
5927
5928 class TearDownRegionSetsClosure : public HeapRegionClosure {
5929 private:
5930 HeapRegionSet *_old_set;
5931
5932 public:
5933 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5934
5935 bool doHeapRegion(HeapRegion* r) {
5936 if (r->is_old()) {
5937 _old_set->remove(r);
5938 } else {
5939 // We ignore free regions, we'll empty the free list afterwards.
5940 // We ignore young regions, we'll empty the young list afterwards.
5941 // We ignore humongous regions, we're not tearing down the
5942 // humongous regions set.
5943 assert(r->is_free() || r->is_young() || r->is_humongous(),
5944 "it cannot be another type");
5945 }
5946 return false;
5947 }
5948
5949 ~TearDownRegionSetsClosure() {
5950 assert(_old_set->is_empty(), "post-condition");
5951 }
5952 };
5953
5954 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5955 assert_at_safepoint(true /* should_be_vm_thread */);
5956
5957 if (!free_list_only) {
5958 TearDownRegionSetsClosure cl(&_old_set);
5959 heap_region_iterate(&cl);
5960
5961 // Note that emptying the _young_list is postponed and instead done as
5962 // the first step when rebuilding the regions sets again. The reason for
5963 // this is that during a full GC string deduplication needs to know if
5964 // a collected region was young or old when the full GC was initiated.
5965 }
5966 _hrm.remove_all_free_regions();
5967 }
5968
5969 void G1CollectedHeap::increase_used(size_t bytes) {
5970 _summary_bytes_used += bytes;
5971 }
5972
5973 void G1CollectedHeap::decrease_used(size_t bytes) {
5974 assert(_summary_bytes_used >= bytes,
5975 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5976 _summary_bytes_used, bytes);
5977 _summary_bytes_used -= bytes;
5978 }
5979
5980 void G1CollectedHeap::set_used(size_t bytes) {
5981 _summary_bytes_used = bytes;
5982 }
5983
5984 class RebuildRegionSetsClosure : public HeapRegionClosure {
5985 private:
5986 bool _free_list_only;
5987 HeapRegionSet* _old_set;
5988 HeapRegionManager* _hrm;
5989 size_t _total_used;
5990
5991 public:
5992 RebuildRegionSetsClosure(bool free_list_only,
5993 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5994 _free_list_only(free_list_only),
5995 _old_set(old_set), _hrm(hrm), _total_used(0) {
5996 assert(_hrm->num_free_regions() == 0, "pre-condition");
5997 if (!free_list_only) {
5998 assert(_old_set->is_empty(), "pre-condition");
5999 }
6000 }
6001
6002 bool doHeapRegion(HeapRegion* r) {
6003 if (r->is_empty()) {
6004 // Add free regions to the free list
6005 r->set_free();
6006 r->set_allocation_context(AllocationContext::system());
6007 _hrm->insert_into_free_list(r);
6008 } else if (!_free_list_only) {
6009 assert(!r->is_young(), "we should not come across young regions");
6010
6011 if (r->is_humongous()) {
6012 // We ignore humongous regions. We left the humongous set unchanged.
6013 } else {
6014 // Objects that were compacted would have ended up on regions
6015 // that were previously old or free. Archive regions (which are
6016 // old) will not have been touched.
6017 assert(r->is_free() || r->is_old(), "invariant");
6018 // We now consider them old, so register as such. Leave
6019 // archive regions set that way, however, while still adding
6020 // them to the old set.
6021 if (!r->is_archive()) {
6022 r->set_old();
6023 }
6024 _old_set->add(r);
6025 }
6026 _total_used += r->used();
6027 }
6028
6029 return false;
6030 }
6031
6032 size_t total_used() {
6033 return _total_used;
6034 }
6035 };
6036
6037 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6038 assert_at_safepoint(true /* should_be_vm_thread */);
6039
6040 if (!free_list_only) {
6041 _young_list->empty_list();
6042 }
6043
6044 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6045 heap_region_iterate(&cl);
6046
6047 if (!free_list_only) {
6048 set_used(cl.total_used());
6049 if (_archive_allocator != NULL) {
6050 _archive_allocator->clear_used();
6051 }
6052 }
6053 assert(used_unlocked() == recalculate_used(),
6054 "inconsistent used_unlocked(), "
6055 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6056 used_unlocked(), recalculate_used());
6057 }
6058
6059 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6060 _refine_cte_cl->set_concurrent(concurrent);
6061 }
6062
6063 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6064 HeapRegion* hr = heap_region_containing(p);
6065 return hr->is_in(p);
6066 }
6067
6068 // Methods for the mutator alloc region
6069
6070 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6071 bool force) {
6072 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6073 assert(!force || g1_policy()->can_expand_young_list(),
6074 "if force is true we should be able to expand the young list");
6075 bool young_list_full = g1_policy()->is_young_list_full();
6076 if (force || !young_list_full) {
6077 HeapRegion* new_alloc_region = new_region(word_size,
6078 false /* is_old */,
6079 false /* do_expand */);
6080 if (new_alloc_region != NULL) {
6081 set_region_short_lived_locked(new_alloc_region);
6082 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6083 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6084 return new_alloc_region;
6085 }
6086 }
6087 return NULL;
6088 }
6089
6090 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6091 size_t allocated_bytes) {
6092 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6093 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6094
6095 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6096 increase_used(allocated_bytes);
6097 _hr_printer.retire(alloc_region);
6098 // We update the eden sizes here, when the region is retired,
6099 // instead of when it's allocated, since this is the point that its
6100 // used space has been recored in _summary_bytes_used.
6101 g1mm()->update_eden_size();
6102 }
6103
6104 // Methods for the GC alloc regions
6105
6106 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6107 uint count,
6108 InCSetState dest) {
6109 assert(FreeList_lock->owned_by_self(), "pre-condition");
6110
6111 if (count < g1_policy()->max_regions(dest)) {
6112 const bool is_survivor = (dest.is_young());
6113 HeapRegion* new_alloc_region = new_region(word_size,
6114 !is_survivor,
6115 true /* do_expand */);
6116 if (new_alloc_region != NULL) {
6117 // We really only need to do this for old regions given that we
6118 // should never scan survivors. But it doesn't hurt to do it
6119 // for survivors too.
6120 new_alloc_region->record_timestamp();
6121 if (is_survivor) {
6122 new_alloc_region->set_survivor();
6123 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6124 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6125 } else {
6126 new_alloc_region->set_old();
6127 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6128 check_bitmaps("Old Region Allocation", new_alloc_region);
6129 }
6130 bool during_im = collector_state()->during_initial_mark_pause();
6131 new_alloc_region->note_start_of_copying(during_im);
6132 return new_alloc_region;
6133 }
6134 }
6135 return NULL;
6136 }
6137
6138 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6139 size_t allocated_bytes,
6140 InCSetState dest) {
6141 bool during_im = collector_state()->during_initial_mark_pause();
6142 alloc_region->note_end_of_copying(during_im);
6143 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6144 if (dest.is_young()) {
6145 young_list()->add_survivor_region(alloc_region);
6146 } else {
6147 _old_set.add(alloc_region);
6148 }
6149 _hr_printer.retire(alloc_region);
6150 }
6151
6152 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6153 bool expanded = false;
6154 uint index = _hrm.find_highest_free(&expanded);
6155
6156 if (index != G1_NO_HRM_INDEX) {
6157 if (expanded) {
6158 ergo_verbose1(ErgoHeapSizing,
6159 "attempt heap expansion",
6160 ergo_format_reason("requested address range outside heap bounds")
6161 ergo_format_byte("region size"),
6162 HeapRegion::GrainWords * HeapWordSize);
6163 }
6164 _hrm.allocate_free_regions_starting_at(index, 1);
6165 return region_at(index);
6166 }
6167 return NULL;
6168 }
6169
6170 // Heap region set verification
6171
6172 class VerifyRegionListsClosure : public HeapRegionClosure {
6173 private:
6174 HeapRegionSet* _old_set;
6175 HeapRegionSet* _humongous_set;
6176 HeapRegionManager* _hrm;
6177
6178 public:
6179 HeapRegionSetCount _old_count;
6180 HeapRegionSetCount _humongous_count;
6181 HeapRegionSetCount _free_count;
6182
6183 VerifyRegionListsClosure(HeapRegionSet* old_set,
6184 HeapRegionSet* humongous_set,
6185 HeapRegionManager* hrm) :
6186 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6187 _old_count(), _humongous_count(), _free_count(){ }
6188
6189 bool doHeapRegion(HeapRegion* hr) {
6190 if (hr->is_young()) {
6191 // TODO
6192 } else if (hr->is_humongous()) {
6193 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6194 _humongous_count.increment(1u, hr->capacity());
6195 } else if (hr->is_empty()) {
6196 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6197 _free_count.increment(1u, hr->capacity());
6198 } else if (hr->is_old()) {
6199 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6200 _old_count.increment(1u, hr->capacity());
6201 } else {
6202 // There are no other valid region types. Check for one invalid
6203 // one we can identify: pinned without old or humongous set.
6204 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6205 ShouldNotReachHere();
6206 }
6207 return false;
6208 }
6209
6210 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6211 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6212 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6213 old_set->total_capacity_bytes(), _old_count.capacity());
6214
6215 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6216 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6217 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6218
6219 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());
6220 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6221 free_list->total_capacity_bytes(), _free_count.capacity());
6222 }
6223 };
6224
6225 void G1CollectedHeap::verify_region_sets() {
6226 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6227
6228 // First, check the explicit lists.
6229 _hrm.verify();
6230 {
6231 // Given that a concurrent operation might be adding regions to
6232 // the secondary free list we have to take the lock before
6233 // verifying it.
6234 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6235 _secondary_free_list.verify_list();
6236 }
6237
6238 // If a concurrent region freeing operation is in progress it will
6239 // be difficult to correctly attributed any free regions we come
6240 // across to the correct free list given that they might belong to
6241 // one of several (free_list, secondary_free_list, any local lists,
6242 // etc.). So, if that's the case we will skip the rest of the
6243 // verification operation. Alternatively, waiting for the concurrent
6244 // operation to complete will have a non-trivial effect on the GC's
6245 // operation (no concurrent operation will last longer than the
6246 // interval between two calls to verification) and it might hide
6247 // any issues that we would like to catch during testing.
6248 if (free_regions_coming()) {
6249 return;
6250 }
6251
6252 // Make sure we append the secondary_free_list on the free_list so
6253 // that all free regions we will come across can be safely
6254 // attributed to the free_list.
6255 append_secondary_free_list_if_not_empty_with_lock();
6256
6257 // Finally, make sure that the region accounting in the lists is
6258 // consistent with what we see in the heap.
6259
6260 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6261 heap_region_iterate(&cl);
6262 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6263 }
6264
6265 // Optimized nmethod scanning
6266
6267 class RegisterNMethodOopClosure: public OopClosure {
6268 G1CollectedHeap* _g1h;
6269 nmethod* _nm;
6270
6271 template <class T> void do_oop_work(T* p) {
6272 T heap_oop = oopDesc::load_heap_oop(p);
6273 if (!oopDesc::is_null(heap_oop)) {
6274 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6275 HeapRegion* hr = _g1h->heap_region_containing(obj);
6276 assert(!hr->is_continues_humongous(),
6277 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6278 " starting at " HR_FORMAT,
6279 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6280
6281 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6282 hr->add_strong_code_root_locked(_nm);
6283 }
6284 }
6285
6286 public:
6287 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6288 _g1h(g1h), _nm(nm) {}
6289
6290 void do_oop(oop* p) { do_oop_work(p); }
6291 void do_oop(narrowOop* p) { do_oop_work(p); }
6292 };
6293
6294 class UnregisterNMethodOopClosure: public OopClosure {
6295 G1CollectedHeap* _g1h;
6296 nmethod* _nm;
6297
6298 template <class T> void do_oop_work(T* p) {
6299 T heap_oop = oopDesc::load_heap_oop(p);
6300 if (!oopDesc::is_null(heap_oop)) {
6301 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6302 HeapRegion* hr = _g1h->heap_region_containing(obj);
6303 assert(!hr->is_continues_humongous(),
6304 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6305 " starting at " HR_FORMAT,
6306 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6307
6308 hr->remove_strong_code_root(_nm);
6309 }
6310 }
6311
6312 public:
6313 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6314 _g1h(g1h), _nm(nm) {}
6315
6316 void do_oop(oop* p) { do_oop_work(p); }
6317 void do_oop(narrowOop* p) { do_oop_work(p); }
6318 };
6319
6320 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6321 CollectedHeap::register_nmethod(nm);
6322
6323 guarantee(nm != NULL, "sanity");
6324 RegisterNMethodOopClosure reg_cl(this, nm);
6325 nm->oops_do(®_cl);
6326 }
6327
6328 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6329 CollectedHeap::unregister_nmethod(nm);
6330
6331 guarantee(nm != NULL, "sanity");
6332 UnregisterNMethodOopClosure reg_cl(this, nm);
6333 nm->oops_do(®_cl, true);
6334 }
6335
6336 void G1CollectedHeap::purge_code_root_memory() {
6337 double purge_start = os::elapsedTime();
6338 G1CodeRootSet::purge();
6339 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6340 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6341 }
6342
6343 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6344 G1CollectedHeap* _g1h;
6345
6346 public:
6347 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6348 _g1h(g1h) {}
6349
6350 void do_code_blob(CodeBlob* cb) {
6351 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6352 if (nm == NULL) {
6353 return;
6354 }
6355
6356 if (ScavengeRootsInCode) {
6357 _g1h->register_nmethod(nm);
6358 }
6359 }
6360 };
6361
6362 void G1CollectedHeap::rebuild_strong_code_roots() {
6363 RebuildStrongCodeRootClosure blob_cl(this);
6364 CodeCache::blobs_do(&blob_cl);
6365 }