1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1Log.hpp"
43 #include "gc/g1/g1MarkSweep.hpp"
44 #include "gc/g1/g1OopClosures.inline.hpp"
45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc/g1/g1RemSet.inline.hpp"
48 #include "gc/g1/g1RootClosures.hpp"
49 #include "gc/g1/g1RootProcessor.hpp"
50 #include "gc/g1/g1StringDedup.hpp"
51 #include "gc/g1/g1YCTypes.hpp"
52 #include "gc/g1/heapRegion.inline.hpp"
53 #include "gc/g1/heapRegionRemSet.hpp"
54 #include "gc/g1/heapRegionSet.inline.hpp"
55 #include "gc/g1/suspendibleThreadSet.hpp"
56 #include "gc/g1/vm_operations_g1.hpp"
57 #include "gc/shared/gcHeapSummary.hpp"
58 #include "gc/shared/gcId.hpp"
59 #include "gc/shared/gcLocker.inline.hpp"
60 #include "gc/shared/gcTimer.hpp"
61 #include "gc/shared/gcTrace.hpp"
62 #include "gc/shared/gcTraceTime.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "memory/allocation.hpp"
68 #include "memory/iterator.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/init.hpp"
72 #include "runtime/orderAccess.inline.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "utilities/globalDefinitions.hpp"
75 #include "utilities/stack.inline.hpp"
76
77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_processed;
117
118 public:
119 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 *card_ptr = CardTableModRefBS::dirty_card_val();
123 _num_processed++;
124 return true;
125 }
126
127 size_t num_processed() const { return _num_processed; }
128 };
129
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
142 {
143 // Claim the right to put the region on the dirty cards region list
144 // by installing a self pointer.
145 HeapRegion* next = hr->get_next_dirty_cards_region();
146 if (next == NULL) {
147 HeapRegion* res = (HeapRegion*)
148 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
149 NULL);
150 if (res == NULL) {
151 HeapRegion* head;
152 do {
153 // Put the region to the dirty cards region list.
154 head = _dirty_cards_region_list;
155 next = (HeapRegion*)
156 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
157 if (next == head) {
158 assert(hr->get_next_dirty_cards_region() == hr,
159 "hr->get_next_dirty_cards_region() != hr");
160 if (next == NULL) {
161 // The last region in the list points to itself.
162 hr->set_next_dirty_cards_region(hr);
163 } else {
164 hr->set_next_dirty_cards_region(next);
165 }
166 }
167 } while (next != head);
168 }
169 }
170 }
171
172 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
173 {
174 HeapRegion* head;
175 HeapRegion* hr;
176 do {
177 head = _dirty_cards_region_list;
178 if (head == NULL) {
179 return NULL;
180 }
181 HeapRegion* new_head = head->get_next_dirty_cards_region();
182 if (head == new_head) {
183 // The last region.
184 new_head = NULL;
185 }
186 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
187 head);
188 } while (hr != head);
189 assert(hr != NULL, "invariant");
190 hr->set_next_dirty_cards_region(NULL);
191 return hr;
192 }
193
194 // Returns true if the reference points to an object that
195 // can move in an incremental collection.
196 bool G1CollectedHeap::is_scavengable(const void* p) {
197 HeapRegion* hr = heap_region_containing(p);
198 return !hr->is_pinned();
199 }
200
201 // Private methods.
202
203 HeapRegion*
204 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
205 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
206 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
207 if (!_secondary_free_list.is_empty()) {
208 if (G1ConcRegionFreeingVerbose) {
209 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
210 "secondary_free_list has %u entries",
211 _secondary_free_list.length());
212 }
213 // It looks as if there are free regions available on the
214 // secondary_free_list. Let's move them to the free_list and try
215 // again to allocate from it.
216 append_secondary_free_list();
217
218 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
219 "empty we should have moved at least one entry to the free_list");
220 HeapRegion* res = _hrm.allocate_free_region(is_old);
221 if (G1ConcRegionFreeingVerbose) {
222 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
223 "allocated " HR_FORMAT " from secondary_free_list",
224 HR_FORMAT_PARAMS(res));
225 }
226 return res;
227 }
228
229 // Wait here until we get notified either when (a) there are no
230 // more free regions coming or (b) some regions have been moved on
231 // the secondary_free_list.
232 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
233 }
234
235 if (G1ConcRegionFreeingVerbose) {
236 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
237 "could not allocate from secondary_free_list");
238 }
239 return NULL;
240 }
241
242 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
243 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
244 "the only time we use this to allocate a humongous region is "
245 "when we are allocating a single humongous region");
246
247 HeapRegion* res;
248 if (G1StressConcRegionFreeing) {
249 if (!_secondary_free_list.is_empty()) {
250 if (G1ConcRegionFreeingVerbose) {
251 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
252 "forced to look at the secondary_free_list");
253 }
254 res = new_region_try_secondary_free_list(is_old);
255 if (res != NULL) {
256 return res;
257 }
258 }
259 }
260
261 res = _hrm.allocate_free_region(is_old);
262
263 if (res == NULL) {
264 if (G1ConcRegionFreeingVerbose) {
265 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
266 "res == NULL, trying the secondary_free_list");
267 }
268 res = new_region_try_secondary_free_list(is_old);
269 }
270 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
271 // Currently, only attempts to allocate GC alloc regions set
272 // do_expand to true. So, we should only reach here during a
273 // safepoint. If this assumption changes we might have to
274 // reconsider the use of _expand_heap_after_alloc_failure.
275 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
276
277 ergo_verbose1(ErgoHeapSizing,
278 "attempt heap expansion",
279 ergo_format_reason("region allocation request failed")
280 ergo_format_byte("allocation request"),
281 word_size * HeapWordSize);
282 if (expand(word_size * HeapWordSize)) {
283 // Given that expand() succeeded in expanding the heap, and we
284 // always expand the heap by an amount aligned to the heap
285 // region size, the free list should in theory not be empty.
286 // In either case allocate_free_region() will check for NULL.
287 res = _hrm.allocate_free_region(is_old);
288 } else {
289 _expand_heap_after_alloc_failure = false;
290 }
291 }
292 return res;
293 }
294
295 HeapWord*
296 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
297 uint num_regions,
298 size_t word_size,
299 AllocationContext_t context) {
300 assert(first != G1_NO_HRM_INDEX, "pre-condition");
301 assert(is_humongous(word_size), "word_size should be humongous");
302 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
303
304 // Index of last region in the series.
305 uint last = first + num_regions - 1;
306
307 // We need to initialize the region(s) we just discovered. This is
308 // a bit tricky given that it can happen concurrently with
309 // refinement threads refining cards on these regions and
310 // potentially wanting to refine the BOT as they are scanning
311 // those cards (this can happen shortly after a cleanup; see CR
312 // 6991377). So we have to set up the region(s) carefully and in
313 // a specific order.
314
315 // The word size sum of all the regions we will allocate.
316 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
317 assert(word_size <= word_size_sum, "sanity");
318
319 // This will be the "starts humongous" region.
320 HeapRegion* first_hr = region_at(first);
321 // The header of the new object will be placed at the bottom of
322 // the first region.
323 HeapWord* new_obj = first_hr->bottom();
324 // This will be the new top of the new object.
325 HeapWord* obj_top = new_obj + word_size;
326
327 // First, we need to zero the header of the space that we will be
328 // allocating. When we update top further down, some refinement
329 // threads might try to scan the region. By zeroing the header we
330 // ensure that any thread that will try to scan the region will
331 // come across the zero klass word and bail out.
332 //
333 // NOTE: It would not have been correct to have used
334 // CollectedHeap::fill_with_object() and make the space look like
335 // an int array. The thread that is doing the allocation will
336 // later update the object header to a potentially different array
337 // type and, for a very short period of time, the klass and length
338 // fields will be inconsistent. This could cause a refinement
339 // thread to calculate the object size incorrectly.
340 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
341
342 // How many words we use for filler objects.
343 size_t word_fill_size = word_size_sum - word_size;
344
345 // How many words memory we "waste" which cannot hold a filler object.
346 size_t words_not_fillable = 0;
347
348 if (word_fill_size >= min_fill_size()) {
349 fill_with_objects(obj_top, word_fill_size);
350 } else if (word_fill_size > 0) {
351 // We have space to fill, but we cannot fit an object there.
352 words_not_fillable = word_fill_size;
353 word_fill_size = 0;
354 }
355
356 // We will set up the first region as "starts humongous". This
357 // will also update the BOT covering all the regions to reflect
358 // that there is a single object that starts at the bottom of the
359 // first region.
360 first_hr->set_starts_humongous(obj_top, word_fill_size);
361 first_hr->set_allocation_context(context);
362 // Then, if there are any, we will set up the "continues
363 // humongous" regions.
364 HeapRegion* hr = NULL;
365 for (uint i = first + 1; i <= last; ++i) {
366 hr = region_at(i);
367 hr->set_continues_humongous(first_hr);
368 hr->set_allocation_context(context);
369 }
370
371 // Up to this point no concurrent thread would have been able to
372 // do any scanning on any region in this series. All the top
373 // fields still point to bottom, so the intersection between
374 // [bottom,top] and [card_start,card_end] will be empty. Before we
375 // update the top fields, we'll do a storestore to make sure that
376 // no thread sees the update to top before the zeroing of the
377 // object header and the BOT initialization.
378 OrderAccess::storestore();
379
380 // Now, we will update the top fields of the "continues humongous"
381 // regions except the last one.
382 for (uint i = first; i < last; ++i) {
383 hr = region_at(i);
384 hr->set_top(hr->end());
385 }
386
387 hr = region_at(last);
388 // If we cannot fit a filler object, we must set top to the end
389 // of the humongous object, otherwise we cannot iterate the heap
390 // and the BOT will not be complete.
391 hr->set_top(hr->end() - words_not_fillable);
392
393 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
394 "obj_top should be in last region");
395
396 check_bitmaps("Humongous Region Allocation", first_hr);
397
398 assert(words_not_fillable == 0 ||
399 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
400 "Miscalculation in humongous allocation");
401
402 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
403
404 for (uint i = first; i <= last; ++i) {
405 hr = region_at(i);
406 _humongous_set.add(hr);
407 if (i == first) {
408 _hr_printer.alloc(G1HRPrinter::StartsHumongous, hr, hr->top());
409 } else {
410 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->top());
411 }
412 }
413
414 return new_obj;
415 }
416
417 // If could fit into free regions w/o expansion, try.
418 // Otherwise, if can expand, do so.
419 // Otherwise, if using ex regions might help, try with ex given back.
420 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
421 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
422
423 verify_region_sets_optional();
424
425 uint first = G1_NO_HRM_INDEX;
426 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
427
428 if (obj_regions == 1) {
429 // Only one region to allocate, try to use a fast path by directly allocating
430 // from the free lists. Do not try to expand here, we will potentially do that
431 // later.
432 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
433 if (hr != NULL) {
434 first = hr->hrm_index();
435 }
436 } else {
437 // We can't allocate humongous regions spanning more than one region while
438 // cleanupComplete() is running, since some of the regions we find to be
439 // empty might not yet be added to the free list. It is not straightforward
440 // to know in which list they are on so that we can remove them. We only
441 // need to do this if we need to allocate more than one region to satisfy the
442 // current humongous allocation request. If we are only allocating one region
443 // we use the one-region region allocation code (see above), that already
444 // potentially waits for regions from the secondary free list.
445 wait_while_free_regions_coming();
446 append_secondary_free_list_if_not_empty_with_lock();
447
448 // Policy: Try only empty regions (i.e. already committed first). Maybe we
449 // are lucky enough to find some.
450 first = _hrm.find_contiguous_only_empty(obj_regions);
451 if (first != G1_NO_HRM_INDEX) {
452 _hrm.allocate_free_regions_starting_at(first, obj_regions);
453 }
454 }
455
456 if (first == G1_NO_HRM_INDEX) {
457 // Policy: We could not find enough regions for the humongous object in the
458 // free list. Look through the heap to find a mix of free and uncommitted regions.
459 // If so, try expansion.
460 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
461 if (first != G1_NO_HRM_INDEX) {
462 // We found something. Make sure these regions are committed, i.e. expand
463 // the heap. Alternatively we could do a defragmentation GC.
464 ergo_verbose1(ErgoHeapSizing,
465 "attempt heap expansion",
466 ergo_format_reason("humongous allocation request failed")
467 ergo_format_byte("allocation request"),
468 word_size * HeapWordSize);
469
470 _hrm.expand_at(first, obj_regions);
471 g1_policy()->record_new_heap_size(num_regions());
472
473 #ifdef ASSERT
474 for (uint i = first; i < first + obj_regions; ++i) {
475 HeapRegion* hr = region_at(i);
476 assert(hr->is_free(), "sanity");
477 assert(hr->is_empty(), "sanity");
478 assert(is_on_master_free_list(hr), "sanity");
479 }
480 #endif
481 _hrm.allocate_free_regions_starting_at(first, obj_regions);
482 } else {
483 // Policy: Potentially trigger a defragmentation GC.
484 }
485 }
486
487 HeapWord* result = NULL;
488 if (first != G1_NO_HRM_INDEX) {
489 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
490 word_size, context);
491 assert(result != NULL, "it should always return a valid result");
492
493 // A successful humongous object allocation changes the used space
494 // information of the old generation so we need to recalculate the
495 // sizes and update the jstat counters here.
496 g1mm()->update_sizes();
497 }
498
499 verify_region_sets_optional();
500
501 return result;
502 }
503
504 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
505 assert_heap_not_locked_and_not_at_safepoint();
506 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
507
508 uint dummy_gc_count_before;
509 uint dummy_gclocker_retry_count = 0;
510 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
511 }
512
513 HeapWord*
514 G1CollectedHeap::mem_allocate(size_t word_size,
515 bool* gc_overhead_limit_was_exceeded) {
516 assert_heap_not_locked_and_not_at_safepoint();
517
518 // Loop until the allocation is satisfied, or unsatisfied after GC.
519 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
520 uint gc_count_before;
521
522 HeapWord* result = NULL;
523 if (!is_humongous(word_size)) {
524 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
525 } else {
526 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
527 }
528 if (result != NULL) {
529 return result;
530 }
531
532 // Create the garbage collection operation...
533 VM_G1CollectForAllocation op(gc_count_before, word_size);
534 op.set_allocation_context(AllocationContext::current());
535
536 // ...and get the VM thread to execute it.
537 VMThread::execute(&op);
538
539 if (op.prologue_succeeded() && op.pause_succeeded()) {
540 // If the operation was successful we'll return the result even
541 // if it is NULL. If the allocation attempt failed immediately
542 // after a Full GC, it's unlikely we'll be able to allocate now.
543 HeapWord* result = op.result();
544 if (result != NULL && !is_humongous(word_size)) {
545 // Allocations that take place on VM operations do not do any
546 // card dirtying and we have to do it here. We only have to do
547 // this for non-humongous allocations, though.
548 dirty_young_block(result, word_size);
549 }
550 return result;
551 } else {
552 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
553 return NULL;
554 }
555 assert(op.result() == NULL,
556 "the result should be NULL if the VM op did not succeed");
557 }
558
559 // Give a warning if we seem to be looping forever.
560 if ((QueuedAllocationWarningCount > 0) &&
561 (try_count % QueuedAllocationWarningCount == 0)) {
562 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
563 }
564 }
565
566 ShouldNotReachHere();
567 return NULL;
568 }
569
570 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
571 AllocationContext_t context,
572 uint* gc_count_before_ret,
573 uint* gclocker_retry_count_ret) {
574 // Make sure you read the note in attempt_allocation_humongous().
575
576 assert_heap_not_locked_and_not_at_safepoint();
577 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
578 "be called for humongous allocation requests");
579
580 // We should only get here after the first-level allocation attempt
581 // (attempt_allocation()) failed to allocate.
582
583 // We will loop until a) we manage to successfully perform the
584 // allocation or b) we successfully schedule a collection which
585 // fails to perform the allocation. b) is the only case when we'll
586 // return NULL.
587 HeapWord* result = NULL;
588 for (int try_count = 1; /* we'll return */; try_count += 1) {
589 bool should_try_gc;
590 uint gc_count_before;
591
592 {
593 MutexLockerEx x(Heap_lock);
594 result = _allocator->attempt_allocation_locked(word_size, context);
595 if (result != NULL) {
596 return result;
597 }
598
599 if (GC_locker::is_active_and_needs_gc()) {
600 if (g1_policy()->can_expand_young_list()) {
601 // No need for an ergo verbose message here,
602 // can_expand_young_list() does this when it returns true.
603 result = _allocator->attempt_allocation_force(word_size, context);
604 if (result != NULL) {
605 return result;
606 }
607 }
608 should_try_gc = false;
609 } else {
610 // The GCLocker may not be active but the GCLocker initiated
611 // GC may not yet have been performed (GCLocker::needs_gc()
612 // returns true). In this case we do not try this GC and
613 // wait until the GCLocker initiated GC is performed, and
614 // then retry the allocation.
615 if (GC_locker::needs_gc()) {
616 should_try_gc = false;
617 } else {
618 // Read the GC count while still holding the Heap_lock.
619 gc_count_before = total_collections();
620 should_try_gc = true;
621 }
622 }
623 }
624
625 if (should_try_gc) {
626 bool succeeded;
627 result = do_collection_pause(word_size, gc_count_before, &succeeded,
628 GCCause::_g1_inc_collection_pause);
629 if (result != NULL) {
630 assert(succeeded, "only way to get back a non-NULL result");
631 return result;
632 }
633
634 if (succeeded) {
635 // If we get here we successfully scheduled a collection which
636 // failed to allocate. No point in trying to allocate
637 // further. We'll just return NULL.
638 MutexLockerEx x(Heap_lock);
639 *gc_count_before_ret = total_collections();
640 return NULL;
641 }
642 } else {
643 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
644 MutexLockerEx x(Heap_lock);
645 *gc_count_before_ret = total_collections();
646 return NULL;
647 }
648 // The GCLocker is either active or the GCLocker initiated
649 // GC has not yet been performed. Stall until it is and
650 // then retry the allocation.
651 GC_locker::stall_until_clear();
652 (*gclocker_retry_count_ret) += 1;
653 }
654
655 // We can reach here if we were unsuccessful in scheduling a
656 // collection (because another thread beat us to it) or if we were
657 // stalled due to the GC locker. In either can we should retry the
658 // allocation attempt in case another thread successfully
659 // performed a collection and reclaimed enough space. We do the
660 // first attempt (without holding the Heap_lock) here and the
661 // follow-on attempt will be at the start of the next loop
662 // iteration (after taking the Heap_lock).
663 result = _allocator->attempt_allocation(word_size, context);
664 if (result != NULL) {
665 return result;
666 }
667
668 // Give a warning if we seem to be looping forever.
669 if ((QueuedAllocationWarningCount > 0) &&
670 (try_count % QueuedAllocationWarningCount == 0)) {
671 warning("G1CollectedHeap::attempt_allocation_slow() "
672 "retries %d times", try_count);
673 }
674 }
675
676 ShouldNotReachHere();
677 return NULL;
678 }
679
680 void G1CollectedHeap::begin_archive_alloc_range() {
681 assert_at_safepoint(true /* should_be_vm_thread */);
682 if (_archive_allocator == NULL) {
683 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
684 }
685 }
686
687 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
688 // Allocations in archive regions cannot be of a size that would be considered
689 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
690 // may be different at archive-restore time.
691 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
692 }
693
694 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
695 assert_at_safepoint(true /* should_be_vm_thread */);
696 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
697 if (is_archive_alloc_too_large(word_size)) {
698 return NULL;
699 }
700 return _archive_allocator->archive_mem_allocate(word_size);
701 }
702
703 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
704 size_t end_alignment_in_bytes) {
705 assert_at_safepoint(true /* should_be_vm_thread */);
706 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
707
708 // Call complete_archive to do the real work, filling in the MemRegion
709 // array with the archive regions.
710 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
711 delete _archive_allocator;
712 _archive_allocator = NULL;
713 }
714
715 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
716 assert(ranges != NULL, "MemRegion array NULL");
717 assert(count != 0, "No MemRegions provided");
718 MemRegion reserved = _hrm.reserved();
719 for (size_t i = 0; i < count; i++) {
720 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
721 return false;
722 }
723 }
724 return true;
725 }
726
727 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
728 assert(!is_init_completed(), "Expect to be called at JVM init time");
729 assert(ranges != NULL, "MemRegion array NULL");
730 assert(count != 0, "No MemRegions provided");
731 MutexLockerEx x(Heap_lock);
732
733 MemRegion reserved = _hrm.reserved();
734 HeapWord* prev_last_addr = NULL;
735 HeapRegion* prev_last_region = NULL;
736
737 // Temporarily disable pretouching of heap pages. This interface is used
738 // when mmap'ing archived heap data in, so pre-touching is wasted.
739 FlagSetting fs(AlwaysPreTouch, false);
740
741 // Enable archive object checking in G1MarkSweep. We have to let it know
742 // about each archive range, so that objects in those ranges aren't marked.
743 G1MarkSweep::enable_archive_object_check();
744
745 // For each specified MemRegion range, allocate the corresponding G1
746 // regions and mark them as archive regions. We expect the ranges in
747 // ascending starting address order, without overlap.
748 for (size_t i = 0; i < count; i++) {
749 MemRegion curr_range = ranges[i];
750 HeapWord* start_address = curr_range.start();
751 size_t word_size = curr_range.word_size();
752 HeapWord* last_address = curr_range.last();
753 size_t commits = 0;
754
755 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
756 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
757 p2i(start_address), p2i(last_address));
758 guarantee(start_address > prev_last_addr,
759 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
760 p2i(start_address), p2i(prev_last_addr));
761 prev_last_addr = last_address;
762
763 // Check for ranges that start in the same G1 region in which the previous
764 // range ended, and adjust the start address so we don't try to allocate
765 // the same region again. If the current range is entirely within that
766 // region, skip it, just adjusting the recorded top.
767 HeapRegion* start_region = _hrm.addr_to_region(start_address);
768 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
769 start_address = start_region->end();
770 if (start_address > last_address) {
771 increase_used(word_size * HeapWordSize);
772 start_region->set_top(last_address + 1);
773 continue;
774 }
775 start_region->set_top(start_address);
776 curr_range = MemRegion(start_address, last_address + 1);
777 start_region = _hrm.addr_to_region(start_address);
778 }
779
780 // Perform the actual region allocation, exiting if it fails.
781 // Then note how much new space we have allocated.
782 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
783 return false;
784 }
785 increase_used(word_size * HeapWordSize);
786 if (commits != 0) {
787 ergo_verbose1(ErgoHeapSizing,
788 "attempt heap expansion",
789 ergo_format_reason("allocate archive regions")
790 ergo_format_byte("total size"),
791 HeapRegion::GrainWords * HeapWordSize * commits);
792 }
793
794 // Mark each G1 region touched by the range as archive, add it to the old set,
795 // and set the allocation context and top.
796 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
797 HeapRegion* last_region = _hrm.addr_to_region(last_address);
798 prev_last_region = last_region;
799
800 while (curr_region != NULL) {
801 assert(curr_region->is_empty() && !curr_region->is_pinned(),
802 "Region already in use (index %u)", curr_region->hrm_index());
803 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
804 curr_region->set_allocation_context(AllocationContext::system());
805 curr_region->set_archive();
806 _old_set.add(curr_region);
807 if (curr_region != last_region) {
808 curr_region->set_top(curr_region->end());
809 curr_region = _hrm.next_region_in_heap(curr_region);
810 } else {
811 curr_region->set_top(last_address + 1);
812 curr_region = NULL;
813 }
814 }
815
816 // Notify mark-sweep of the archive range.
817 G1MarkSweep::set_range_archive(curr_range, true);
818 }
819 return true;
820 }
821
822 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
823 assert(!is_init_completed(), "Expect to be called at JVM init time");
824 assert(ranges != NULL, "MemRegion array NULL");
825 assert(count != 0, "No MemRegions provided");
826 MemRegion reserved = _hrm.reserved();
827 HeapWord *prev_last_addr = NULL;
828 HeapRegion* prev_last_region = NULL;
829
830 // For each MemRegion, create filler objects, if needed, in the G1 regions
831 // that contain the address range. The address range actually within the
832 // MemRegion will not be modified. That is assumed to have been initialized
833 // elsewhere, probably via an mmap of archived heap data.
834 MutexLockerEx x(Heap_lock);
835 for (size_t i = 0; i < count; i++) {
836 HeapWord* start_address = ranges[i].start();
837 HeapWord* last_address = ranges[i].last();
838
839 assert(reserved.contains(start_address) && reserved.contains(last_address),
840 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
841 p2i(start_address), p2i(last_address));
842 assert(start_address > prev_last_addr,
843 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
844 p2i(start_address), p2i(prev_last_addr));
845
846 HeapRegion* start_region = _hrm.addr_to_region(start_address);
847 HeapRegion* last_region = _hrm.addr_to_region(last_address);
848 HeapWord* bottom_address = start_region->bottom();
849
850 // Check for a range beginning in the same region in which the
851 // previous one ended.
852 if (start_region == prev_last_region) {
853 bottom_address = prev_last_addr + 1;
854 }
855
856 // Verify that the regions were all marked as archive regions by
857 // alloc_archive_regions.
858 HeapRegion* curr_region = start_region;
859 while (curr_region != NULL) {
860 guarantee(curr_region->is_archive(),
861 "Expected archive region at index %u", curr_region->hrm_index());
862 if (curr_region != last_region) {
863 curr_region = _hrm.next_region_in_heap(curr_region);
864 } else {
865 curr_region = NULL;
866 }
867 }
868
869 prev_last_addr = last_address;
870 prev_last_region = last_region;
871
872 // Fill the memory below the allocated range with dummy object(s),
873 // if the region bottom does not match the range start, or if the previous
874 // range ended within the same G1 region, and there is a gap.
875 if (start_address != bottom_address) {
876 size_t fill_size = pointer_delta(start_address, bottom_address);
877 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
878 increase_used(fill_size * HeapWordSize);
879 }
880 }
881 }
882
883 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
884 uint* gc_count_before_ret,
885 uint* gclocker_retry_count_ret) {
886 assert_heap_not_locked_and_not_at_safepoint();
887 assert(!is_humongous(word_size), "attempt_allocation() should not "
888 "be called for humongous allocation requests");
889
890 AllocationContext_t context = AllocationContext::current();
891 HeapWord* result = _allocator->attempt_allocation(word_size, context);
892
893 if (result == NULL) {
894 result = attempt_allocation_slow(word_size,
895 context,
896 gc_count_before_ret,
897 gclocker_retry_count_ret);
898 }
899 assert_heap_not_locked();
900 if (result != NULL) {
901 dirty_young_block(result, word_size);
902 }
903 return result;
904 }
905
906 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
907 assert(!is_init_completed(), "Expect to be called at JVM init time");
908 assert(ranges != NULL, "MemRegion array NULL");
909 assert(count != 0, "No MemRegions provided");
910 MemRegion reserved = _hrm.reserved();
911 HeapWord* prev_last_addr = NULL;
912 HeapRegion* prev_last_region = NULL;
913 size_t size_used = 0;
914 size_t uncommitted_regions = 0;
915
916 // For each Memregion, free the G1 regions that constitute it, and
917 // notify mark-sweep that the range is no longer to be considered 'archive.'
918 MutexLockerEx x(Heap_lock);
919 for (size_t i = 0; i < count; i++) {
920 HeapWord* start_address = ranges[i].start();
921 HeapWord* last_address = ranges[i].last();
922
923 assert(reserved.contains(start_address) && reserved.contains(last_address),
924 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
925 p2i(start_address), p2i(last_address));
926 assert(start_address > prev_last_addr,
927 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
928 p2i(start_address), p2i(prev_last_addr));
929 size_used += ranges[i].byte_size();
930 prev_last_addr = last_address;
931
932 HeapRegion* start_region = _hrm.addr_to_region(start_address);
933 HeapRegion* last_region = _hrm.addr_to_region(last_address);
934
935 // Check for ranges that start in the same G1 region in which the previous
936 // range ended, and adjust the start address so we don't try to free
937 // the same region again. If the current range is entirely within that
938 // region, skip it.
939 if (start_region == prev_last_region) {
940 start_address = start_region->end();
941 if (start_address > last_address) {
942 continue;
943 }
944 start_region = _hrm.addr_to_region(start_address);
945 }
946 prev_last_region = last_region;
947
948 // After verifying that each region was marked as an archive region by
949 // alloc_archive_regions, set it free and empty and uncommit it.
950 HeapRegion* curr_region = start_region;
951 while (curr_region != NULL) {
952 guarantee(curr_region->is_archive(),
953 "Expected archive region at index %u", curr_region->hrm_index());
954 uint curr_index = curr_region->hrm_index();
955 _old_set.remove(curr_region);
956 curr_region->set_free();
957 curr_region->set_top(curr_region->bottom());
958 if (curr_region != last_region) {
959 curr_region = _hrm.next_region_in_heap(curr_region);
960 } else {
961 curr_region = NULL;
962 }
963 _hrm.shrink_at(curr_index, 1);
964 uncommitted_regions++;
965 }
966
967 // Notify mark-sweep that this is no longer an archive range.
968 G1MarkSweep::set_range_archive(ranges[i], false);
969 }
970
971 if (uncommitted_regions != 0) {
972 ergo_verbose1(ErgoHeapSizing,
973 "attempt heap shrinking",
974 ergo_format_reason("uncommitted archive regions")
975 ergo_format_byte("total size"),
976 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
977 }
978 decrease_used(size_used);
979 }
980
981 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
982 uint* gc_count_before_ret,
983 uint* gclocker_retry_count_ret) {
984 // The structure of this method has a lot of similarities to
985 // attempt_allocation_slow(). The reason these two were not merged
986 // into a single one is that such a method would require several "if
987 // allocation is not humongous do this, otherwise do that"
988 // conditional paths which would obscure its flow. In fact, an early
989 // version of this code did use a unified method which was harder to
990 // follow and, as a result, it had subtle bugs that were hard to
991 // track down. So keeping these two methods separate allows each to
992 // be more readable. It will be good to keep these two in sync as
993 // much as possible.
994
995 assert_heap_not_locked_and_not_at_safepoint();
996 assert(is_humongous(word_size), "attempt_allocation_humongous() "
997 "should only be called for humongous allocations");
998
999 // Humongous objects can exhaust the heap quickly, so we should check if we
1000 // need to start a marking cycle at each humongous object allocation. We do
1001 // the check before we do the actual allocation. The reason for doing it
1002 // before the allocation is that we avoid having to keep track of the newly
1003 // allocated memory while we do a GC.
1004 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1005 word_size)) {
1006 collect(GCCause::_g1_humongous_allocation);
1007 }
1008
1009 // We will loop until a) we manage to successfully perform the
1010 // allocation or b) we successfully schedule a collection which
1011 // fails to perform the allocation. b) is the only case when we'll
1012 // return NULL.
1013 HeapWord* result = NULL;
1014 for (int try_count = 1; /* we'll return */; try_count += 1) {
1015 bool should_try_gc;
1016 uint gc_count_before;
1017
1018 {
1019 MutexLockerEx x(Heap_lock);
1020
1021 // Given that humongous objects are not allocated in young
1022 // regions, we'll first try to do the allocation without doing a
1023 // collection hoping that there's enough space in the heap.
1024 result = humongous_obj_allocate(word_size, AllocationContext::current());
1025 if (result != NULL) {
1026 return result;
1027 }
1028
1029 if (GC_locker::is_active_and_needs_gc()) {
1030 should_try_gc = false;
1031 } else {
1032 // The GCLocker may not be active but the GCLocker initiated
1033 // GC may not yet have been performed (GCLocker::needs_gc()
1034 // returns true). In this case we do not try this GC and
1035 // wait until the GCLocker initiated GC is performed, and
1036 // then retry the allocation.
1037 if (GC_locker::needs_gc()) {
1038 should_try_gc = false;
1039 } else {
1040 // Read the GC count while still holding the Heap_lock.
1041 gc_count_before = total_collections();
1042 should_try_gc = true;
1043 }
1044 }
1045 }
1046
1047 if (should_try_gc) {
1048 // If we failed to allocate the humongous object, we should try to
1049 // do a collection pause (if we're allowed) in case it reclaims
1050 // enough space for the allocation to succeed after the pause.
1051
1052 bool succeeded;
1053 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1054 GCCause::_g1_humongous_allocation);
1055 if (result != NULL) {
1056 assert(succeeded, "only way to get back a non-NULL result");
1057 return result;
1058 }
1059
1060 if (succeeded) {
1061 // If we get here we successfully scheduled a collection which
1062 // failed to allocate. No point in trying to allocate
1063 // further. We'll just return NULL.
1064 MutexLockerEx x(Heap_lock);
1065 *gc_count_before_ret = total_collections();
1066 return NULL;
1067 }
1068 } else {
1069 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1070 MutexLockerEx x(Heap_lock);
1071 *gc_count_before_ret = total_collections();
1072 return NULL;
1073 }
1074 // The GCLocker is either active or the GCLocker initiated
1075 // GC has not yet been performed. Stall until it is and
1076 // then retry the allocation.
1077 GC_locker::stall_until_clear();
1078 (*gclocker_retry_count_ret) += 1;
1079 }
1080
1081 // We can reach here if we were unsuccessful in scheduling a
1082 // collection (because another thread beat us to it) or if we were
1083 // stalled due to the GC locker. In either can we should retry the
1084 // allocation attempt in case another thread successfully
1085 // performed a collection and reclaimed enough space. Give a
1086 // warning if we seem to be looping forever.
1087
1088 if ((QueuedAllocationWarningCount > 0) &&
1089 (try_count % QueuedAllocationWarningCount == 0)) {
1090 warning("G1CollectedHeap::attempt_allocation_humongous() "
1091 "retries %d times", try_count);
1092 }
1093 }
1094
1095 ShouldNotReachHere();
1096 return NULL;
1097 }
1098
1099 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1100 AllocationContext_t context,
1101 bool expect_null_mutator_alloc_region) {
1102 assert_at_safepoint(true /* should_be_vm_thread */);
1103 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1104 "the current alloc region was unexpectedly found to be non-NULL");
1105
1106 if (!is_humongous(word_size)) {
1107 return _allocator->attempt_allocation_locked(word_size, context);
1108 } else {
1109 HeapWord* result = humongous_obj_allocate(word_size, context);
1110 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1111 collector_state()->set_initiate_conc_mark_if_possible(true);
1112 }
1113 return result;
1114 }
1115
1116 ShouldNotReachHere();
1117 }
1118
1119 class PostMCRemSetClearClosure: public HeapRegionClosure {
1120 G1CollectedHeap* _g1h;
1121 ModRefBarrierSet* _mr_bs;
1122 public:
1123 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1124 _g1h(g1h), _mr_bs(mr_bs) {}
1125
1126 bool doHeapRegion(HeapRegion* r) {
1127 HeapRegionRemSet* hrrs = r->rem_set();
1128
1129 _g1h->reset_gc_time_stamps(r);
1130
1131 if (r->is_continues_humongous()) {
1132 // We'll assert that the strong code root list and RSet is empty
1133 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1134 assert(hrrs->occupied() == 0, "RSet should be empty");
1135 } else {
1136 hrrs->clear();
1137 }
1138 // You might think here that we could clear just the cards
1139 // corresponding to the used region. But no: if we leave a dirty card
1140 // in a region we might allocate into, then it would prevent that card
1141 // from being enqueued, and cause it to be missed.
1142 // Re: the performance cost: we shouldn't be doing full GC anyway!
1143 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1144
1145 return false;
1146 }
1147 };
1148
1149 void G1CollectedHeap::clear_rsets_post_compaction() {
1150 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1151 heap_region_iterate(&rs_clear);
1152 }
1153
1154 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1155 G1CollectedHeap* _g1h;
1156 UpdateRSOopClosure _cl;
1157 public:
1158 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1159 _cl(g1->g1_rem_set(), worker_i),
1160 _g1h(g1)
1161 { }
1162
1163 bool doHeapRegion(HeapRegion* r) {
1164 if (!r->is_continues_humongous()) {
1165 _cl.set_from(r);
1166 r->oop_iterate(&_cl);
1167 }
1168 return false;
1169 }
1170 };
1171
1172 class ParRebuildRSTask: public AbstractGangTask {
1173 G1CollectedHeap* _g1;
1174 HeapRegionClaimer _hrclaimer;
1175
1176 public:
1177 ParRebuildRSTask(G1CollectedHeap* g1) :
1178 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1179
1180 void work(uint worker_id) {
1181 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1182 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1183 }
1184 };
1185
1186 class PostCompactionPrinterClosure: public HeapRegionClosure {
1187 private:
1188 G1HRPrinter* _hr_printer;
1189 public:
1190 bool doHeapRegion(HeapRegion* hr) {
1191 assert(!hr->is_young(), "not expecting to find young regions");
1192 if (hr->is_free()) {
1193 // We only generate output for non-empty regions.
1194 } else if (hr->is_starts_humongous()) {
1195 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1196 } else if (hr->is_continues_humongous()) {
1197 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1198 } else if (hr->is_archive()) {
1199 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1200 } else if (hr->is_old()) {
1201 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1202 } else {
1203 ShouldNotReachHere();
1204 }
1205 return false;
1206 }
1207
1208 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1209 : _hr_printer(hr_printer) { }
1210 };
1211
1212 void G1CollectedHeap::print_hrm_post_compaction() {
1213 PostCompactionPrinterClosure cl(hr_printer());
1214 heap_region_iterate(&cl);
1215 }
1216
1217 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1218 bool clear_all_soft_refs) {
1219 assert_at_safepoint(true /* should_be_vm_thread */);
1220
1221 if (GC_locker::check_active_before_gc()) {
1222 return false;
1223 }
1224
1225 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1226 gc_timer->register_gc_start();
1227
1228 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1229 GCIdMark gc_id_mark;
1230 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1231
1232 SvcGCMarker sgcm(SvcGCMarker::FULL);
1233 ResourceMark rm;
1234
1235 G1Log::update_level();
1236 print_heap_before_gc();
1237 trace_heap_before_gc(gc_tracer);
1238
1239 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1240
1241 verify_region_sets_optional();
1242
1243 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1244 collector_policy()->should_clear_all_soft_refs();
1245
1246 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1247
1248 {
1249 IsGCActiveMark x;
1250
1251 // Timing
1252 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1253 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1254
1255 {
1256 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1257 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1258 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1259
1260 g1_policy()->record_full_collection_start();
1261
1262 // Note: When we have a more flexible GC logging framework that
1263 // allows us to add optional attributes to a GC log record we
1264 // could consider timing and reporting how long we wait in the
1265 // following two methods.
1266 wait_while_free_regions_coming();
1267 // If we start the compaction before the CM threads finish
1268 // scanning the root regions we might trip them over as we'll
1269 // be moving objects / updating references. So let's wait until
1270 // they are done. By telling them to abort, they should complete
1271 // early.
1272 _cm->root_regions()->abort();
1273 _cm->root_regions()->wait_until_scan_finished();
1274 append_secondary_free_list_if_not_empty_with_lock();
1275
1276 gc_prologue(true);
1277 increment_total_collections(true /* full gc */);
1278 increment_old_marking_cycles_started();
1279
1280 assert(used() == recalculate_used(), "Should be equal");
1281
1282 verify_before_gc();
1283
1284 check_bitmaps("Full GC Start");
1285 pre_full_gc_dump(gc_timer);
1286
1287 #if defined(COMPILER2) || INCLUDE_JVMCI
1288 DerivedPointerTable::clear();
1289 #endif
1290
1291 // Disable discovery and empty the discovered lists
1292 // for the CM ref processor.
1293 ref_processor_cm()->disable_discovery();
1294 ref_processor_cm()->abandon_partial_discovery();
1295 ref_processor_cm()->verify_no_references_recorded();
1296
1297 // Abandon current iterations of concurrent marking and concurrent
1298 // refinement, if any are in progress. We have to do this before
1299 // wait_until_scan_finished() below.
1300 concurrent_mark()->abort();
1301
1302 // Make sure we'll choose a new allocation region afterwards.
1303 _allocator->release_mutator_alloc_region();
1304 _allocator->abandon_gc_alloc_regions();
1305 g1_rem_set()->cleanupHRRS();
1306
1307 // We should call this after we retire any currently active alloc
1308 // regions so that all the ALLOC / RETIRE events are generated
1309 // before the start GC event.
1310 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1311
1312 // We may have added regions to the current incremental collection
1313 // set between the last GC or pause and now. We need to clear the
1314 // incremental collection set and then start rebuilding it afresh
1315 // after this full GC.
1316 abandon_collection_set(g1_policy()->inc_cset_head());
1317 g1_policy()->clear_incremental_cset();
1318 g1_policy()->stop_incremental_cset_building();
1319
1320 tear_down_region_sets(false /* free_list_only */);
1321 collector_state()->set_gcs_are_young(true);
1322
1323 // See the comments in g1CollectedHeap.hpp and
1324 // G1CollectedHeap::ref_processing_init() about
1325 // how reference processing currently works in G1.
1326
1327 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1328 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1329
1330 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1331 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1332
1333 ref_processor_stw()->enable_discovery();
1334 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1335
1336 // Do collection work
1337 {
1338 HandleMark hm; // Discard invalid handles created during gc
1339 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1340 }
1341
1342 assert(num_free_regions() == 0, "we should not have added any free regions");
1343 rebuild_region_sets(false /* free_list_only */);
1344
1345 // Enqueue any discovered reference objects that have
1346 // not been removed from the discovered lists.
1347 ref_processor_stw()->enqueue_discovered_references();
1348
1349 #if defined(COMPILER2) || INCLUDE_JVMCI
1350 DerivedPointerTable::update_pointers();
1351 #endif
1352
1353 MemoryService::track_memory_usage();
1354
1355 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1356 ref_processor_stw()->verify_no_references_recorded();
1357
1358 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1359 ClassLoaderDataGraph::purge();
1360 MetaspaceAux::verify_metrics();
1361
1362 // Note: since we've just done a full GC, concurrent
1363 // marking is no longer active. Therefore we need not
1364 // re-enable reference discovery for the CM ref processor.
1365 // That will be done at the start of the next marking cycle.
1366 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1367 ref_processor_cm()->verify_no_references_recorded();
1368
1369 reset_gc_time_stamp();
1370 // Since everything potentially moved, we will clear all remembered
1371 // sets, and clear all cards. Later we will rebuild remembered
1372 // sets. We will also reset the GC time stamps of the regions.
1373 clear_rsets_post_compaction();
1374 check_gc_time_stamps();
1375
1376 resize_if_necessary_after_full_collection();
1377
1378 if (_hr_printer.is_active()) {
1379 // We should do this after we potentially resize the heap so
1380 // that all the COMMIT / UNCOMMIT events are generated before
1381 // the end GC event.
1382
1383 print_hrm_post_compaction();
1384 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1385 }
1386
1387 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1388 if (hot_card_cache->use_cache()) {
1389 hot_card_cache->reset_card_counts();
1390 hot_card_cache->reset_hot_cache();
1391 }
1392
1393 // Rebuild remembered sets of all regions.
1394 uint n_workers =
1395 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1396 workers()->active_workers(),
1397 Threads::number_of_non_daemon_threads());
1398 workers()->set_active_workers(n_workers);
1399
1400 ParRebuildRSTask rebuild_rs_task(this);
1401 workers()->run_task(&rebuild_rs_task);
1402
1403 // Rebuild the strong code root lists for each region
1404 rebuild_strong_code_roots();
1405
1406 if (true) { // FIXME
1407 MetaspaceGC::compute_new_size();
1408 }
1409
1410 #ifdef TRACESPINNING
1411 ParallelTaskTerminator::print_termination_counts();
1412 #endif
1413
1414 // Discard all rset updates
1415 JavaThread::dirty_card_queue_set().abandon_logs();
1416 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1417
1418 _young_list->reset_sampled_info();
1419 // At this point there should be no regions in the
1420 // entire heap tagged as young.
1421 assert(check_young_list_empty(true /* check_heap */),
1422 "young list should be empty at this point");
1423
1424 // Update the number of full collections that have been completed.
1425 increment_old_marking_cycles_completed(false /* concurrent */);
1426
1427 _hrm.verify_optional();
1428 verify_region_sets_optional();
1429
1430 verify_after_gc();
1431
1432 // Clear the previous marking bitmap, if needed for bitmap verification.
1433 // Note we cannot do this when we clear the next marking bitmap in
1434 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1435 // objects marked during a full GC against the previous bitmap.
1436 // But we need to clear it before calling check_bitmaps below since
1437 // the full GC has compacted objects and updated TAMS but not updated
1438 // the prev bitmap.
1439 if (G1VerifyBitmaps) {
1440 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1441 }
1442 check_bitmaps("Full GC End");
1443
1444 // Start a new incremental collection set for the next pause
1445 assert(g1_policy()->collection_set() == NULL, "must be");
1446 g1_policy()->start_incremental_cset_building();
1447
1448 clear_cset_fast_test();
1449
1450 _allocator->init_mutator_alloc_region();
1451
1452 g1_policy()->record_full_collection_end();
1453
1454 if (G1Log::fine()) {
1455 g1_policy()->print_heap_transition();
1456 }
1457
1458 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1459 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1460 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1461 // before any GC notifications are raised.
1462 g1mm()->update_sizes();
1463
1464 gc_epilogue(true);
1465 }
1466
1467 if (G1Log::finer()) {
1468 g1_policy()->print_detailed_heap_transition(true /* full */);
1469 }
1470
1471 print_heap_after_gc();
1472 trace_heap_after_gc(gc_tracer);
1473
1474 post_full_gc_dump(gc_timer);
1475
1476 gc_timer->register_gc_end();
1477 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1478 }
1479
1480 return true;
1481 }
1482
1483 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1484 // Currently, there is no facility in the do_full_collection(bool) API to notify
1485 // the caller that the collection did not succeed (e.g., because it was locked
1486 // out by the GC locker). So, right now, we'll ignore the return value.
1487 bool dummy = do_full_collection(true, /* explicit_gc */
1488 clear_all_soft_refs);
1489 }
1490
1491 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1492 // Include bytes that will be pre-allocated to support collections, as "used".
1493 const size_t used_after_gc = used();
1494 const size_t capacity_after_gc = capacity();
1495 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1496
1497 // This is enforced in arguments.cpp.
1498 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1499 "otherwise the code below doesn't make sense");
1500
1501 // We don't have floating point command-line arguments
1502 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1503 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1504 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1505 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1506
1507 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1508 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1509
1510 // We have to be careful here as these two calculations can overflow
1511 // 32-bit size_t's.
1512 double used_after_gc_d = (double) used_after_gc;
1513 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1514 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1515
1516 // Let's make sure that they are both under the max heap size, which
1517 // by default will make them fit into a size_t.
1518 double desired_capacity_upper_bound = (double) max_heap_size;
1519 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1520 desired_capacity_upper_bound);
1521 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1522 desired_capacity_upper_bound);
1523
1524 // We can now safely turn them into size_t's.
1525 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1526 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1527
1528 // This assert only makes sense here, before we adjust them
1529 // with respect to the min and max heap size.
1530 assert(minimum_desired_capacity <= maximum_desired_capacity,
1531 "minimum_desired_capacity = " SIZE_FORMAT ", "
1532 "maximum_desired_capacity = " SIZE_FORMAT,
1533 minimum_desired_capacity, maximum_desired_capacity);
1534
1535 // Should not be greater than the heap max size. No need to adjust
1536 // it with respect to the heap min size as it's a lower bound (i.e.,
1537 // we'll try to make the capacity larger than it, not smaller).
1538 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1539 // Should not be less than the heap min size. No need to adjust it
1540 // with respect to the heap max size as it's an upper bound (i.e.,
1541 // we'll try to make the capacity smaller than it, not greater).
1542 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1543
1544 if (capacity_after_gc < minimum_desired_capacity) {
1545 // Don't expand unless it's significant
1546 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1547 ergo_verbose4(ErgoHeapSizing,
1548 "attempt heap expansion",
1549 ergo_format_reason("capacity lower than "
1550 "min desired capacity after Full GC")
1551 ergo_format_byte("capacity")
1552 ergo_format_byte("occupancy")
1553 ergo_format_byte_perc("min desired capacity"),
1554 capacity_after_gc, used_after_gc,
1555 minimum_desired_capacity, (double) MinHeapFreeRatio);
1556 expand(expand_bytes);
1557
1558 // No expansion, now see if we want to shrink
1559 } else if (capacity_after_gc > maximum_desired_capacity) {
1560 // Capacity too large, compute shrinking size
1561 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1562 ergo_verbose4(ErgoHeapSizing,
1563 "attempt heap shrinking",
1564 ergo_format_reason("capacity higher than "
1565 "max desired capacity after Full GC")
1566 ergo_format_byte("capacity")
1567 ergo_format_byte("occupancy")
1568 ergo_format_byte_perc("max desired capacity"),
1569 capacity_after_gc, used_after_gc,
1570 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1571 shrink(shrink_bytes);
1572 }
1573 }
1574
1575 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1576 AllocationContext_t context,
1577 bool do_gc,
1578 bool clear_all_soft_refs,
1579 bool expect_null_mutator_alloc_region,
1580 bool* gc_succeeded) {
1581 *gc_succeeded = true;
1582 // Let's attempt the allocation first.
1583 HeapWord* result =
1584 attempt_allocation_at_safepoint(word_size,
1585 context,
1586 expect_null_mutator_alloc_region);
1587 if (result != NULL) {
1588 assert(*gc_succeeded, "sanity");
1589 return result;
1590 }
1591
1592 // In a G1 heap, we're supposed to keep allocation from failing by
1593 // incremental pauses. Therefore, at least for now, we'll favor
1594 // expansion over collection. (This might change in the future if we can
1595 // do something smarter than full collection to satisfy a failed alloc.)
1596 result = expand_and_allocate(word_size, context);
1597 if (result != NULL) {
1598 assert(*gc_succeeded, "sanity");
1599 return result;
1600 }
1601
1602 if (do_gc) {
1603 // Expansion didn't work, we'll try to do a Full GC.
1604 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1605 clear_all_soft_refs);
1606 }
1607
1608 return NULL;
1609 }
1610
1611 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1612 AllocationContext_t context,
1613 bool* succeeded) {
1614 assert_at_safepoint(true /* should_be_vm_thread */);
1615
1616 // Attempts to allocate followed by Full GC.
1617 HeapWord* result =
1618 satisfy_failed_allocation_helper(word_size,
1619 context,
1620 true, /* do_gc */
1621 false, /* clear_all_soft_refs */
1622 false, /* expect_null_mutator_alloc_region */
1623 succeeded);
1624
1625 if (result != NULL || !*succeeded) {
1626 return result;
1627 }
1628
1629 // Attempts to allocate followed by Full GC that will collect all soft references.
1630 result = satisfy_failed_allocation_helper(word_size,
1631 context,
1632 true, /* do_gc */
1633 true, /* clear_all_soft_refs */
1634 true, /* expect_null_mutator_alloc_region */
1635 succeeded);
1636
1637 if (result != NULL || !*succeeded) {
1638 return result;
1639 }
1640
1641 // Attempts to allocate, no GC
1642 result = satisfy_failed_allocation_helper(word_size,
1643 context,
1644 false, /* do_gc */
1645 false, /* clear_all_soft_refs */
1646 true, /* expect_null_mutator_alloc_region */
1647 succeeded);
1648
1649 if (result != NULL) {
1650 assert(*succeeded, "sanity");
1651 return result;
1652 }
1653
1654 assert(!collector_policy()->should_clear_all_soft_refs(),
1655 "Flag should have been handled and cleared prior to this point");
1656
1657 // What else? We might try synchronous finalization later. If the total
1658 // space available is large enough for the allocation, then a more
1659 // complete compaction phase than we've tried so far might be
1660 // appropriate.
1661 assert(*succeeded, "sanity");
1662 return NULL;
1663 }
1664
1665 // Attempting to expand the heap sufficiently
1666 // to support an allocation of the given "word_size". If
1667 // successful, perform the allocation and return the address of the
1668 // allocated block, or else "NULL".
1669
1670 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1671 assert_at_safepoint(true /* should_be_vm_thread */);
1672
1673 verify_region_sets_optional();
1674
1675 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1676 ergo_verbose1(ErgoHeapSizing,
1677 "attempt heap expansion",
1678 ergo_format_reason("allocation request failed")
1679 ergo_format_byte("allocation request"),
1680 word_size * HeapWordSize);
1681 if (expand(expand_bytes)) {
1682 _hrm.verify_optional();
1683 verify_region_sets_optional();
1684 return attempt_allocation_at_safepoint(word_size,
1685 context,
1686 false /* expect_null_mutator_alloc_region */);
1687 }
1688 return NULL;
1689 }
1690
1691 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1692 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1693 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1694 HeapRegion::GrainBytes);
1695 ergo_verbose2(ErgoHeapSizing,
1696 "expand the heap",
1697 ergo_format_byte("requested expansion amount")
1698 ergo_format_byte("attempted expansion amount"),
1699 expand_bytes, aligned_expand_bytes);
1700
1701 if (is_maximal_no_gc()) {
1702 ergo_verbose0(ErgoHeapSizing,
1703 "did not expand the heap",
1704 ergo_format_reason("heap already fully expanded"));
1705 return false;
1706 }
1707
1708 double expand_heap_start_time_sec = os::elapsedTime();
1709 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1710 assert(regions_to_expand > 0, "Must expand by at least one region");
1711
1712 uint expanded_by = _hrm.expand_by(regions_to_expand);
1713 if (expand_time_ms != NULL) {
1714 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1715 }
1716
1717 if (expanded_by > 0) {
1718 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1719 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1720 g1_policy()->record_new_heap_size(num_regions());
1721 } else {
1722 ergo_verbose0(ErgoHeapSizing,
1723 "did not expand the heap",
1724 ergo_format_reason("heap expansion operation failed"));
1725 // The expansion of the virtual storage space was unsuccessful.
1726 // Let's see if it was because we ran out of swap.
1727 if (G1ExitOnExpansionFailure &&
1728 _hrm.available() >= regions_to_expand) {
1729 // We had head room...
1730 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1731 }
1732 }
1733 return regions_to_expand > 0;
1734 }
1735
1736 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1737 size_t aligned_shrink_bytes =
1738 ReservedSpace::page_align_size_down(shrink_bytes);
1739 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1740 HeapRegion::GrainBytes);
1741 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1742
1743 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1744 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1745
1746 ergo_verbose3(ErgoHeapSizing,
1747 "shrink the heap",
1748 ergo_format_byte("requested shrinking amount")
1749 ergo_format_byte("aligned shrinking amount")
1750 ergo_format_byte("attempted shrinking amount"),
1751 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1752 if (num_regions_removed > 0) {
1753 g1_policy()->record_new_heap_size(num_regions());
1754 } else {
1755 ergo_verbose0(ErgoHeapSizing,
1756 "did not shrink the heap",
1757 ergo_format_reason("heap shrinking operation failed"));
1758 }
1759 }
1760
1761 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1762 verify_region_sets_optional();
1763
1764 // We should only reach here at the end of a Full GC which means we
1765 // should not not be holding to any GC alloc regions. The method
1766 // below will make sure of that and do any remaining clean up.
1767 _allocator->abandon_gc_alloc_regions();
1768
1769 // Instead of tearing down / rebuilding the free lists here, we
1770 // could instead use the remove_all_pending() method on free_list to
1771 // remove only the ones that we need to remove.
1772 tear_down_region_sets(true /* free_list_only */);
1773 shrink_helper(shrink_bytes);
1774 rebuild_region_sets(true /* free_list_only */);
1775
1776 _hrm.verify_optional();
1777 verify_region_sets_optional();
1778 }
1779
1780 // Public methods.
1781
1782 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1783 CollectedHeap(),
1784 _g1_policy(policy_),
1785 _dirty_card_queue_set(false),
1786 _is_alive_closure_cm(this),
1787 _is_alive_closure_stw(this),
1788 _ref_processor_cm(NULL),
1789 _ref_processor_stw(NULL),
1790 _bot_shared(NULL),
1791 _cg1r(NULL),
1792 _g1mm(NULL),
1793 _refine_cte_cl(NULL),
1794 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1795 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1796 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1797 _humongous_reclaim_candidates(),
1798 _has_humongous_reclaim_candidates(false),
1799 _archive_allocator(NULL),
1800 _free_regions_coming(false),
1801 _young_list(new YoungList(this)),
1802 _gc_time_stamp(0),
1803 _summary_bytes_used(0),
1804 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1805 _old_evac_stats(OldPLABSize, PLABWeight),
1806 _expand_heap_after_alloc_failure(true),
1807 _old_marking_cycles_started(0),
1808 _old_marking_cycles_completed(0),
1809 _heap_summary_sent(false),
1810 _in_cset_fast_test(),
1811 _dirty_cards_region_list(NULL),
1812 _worker_cset_start_region(NULL),
1813 _worker_cset_start_region_time_stamp(NULL),
1814 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1815 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1816 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1817 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1818
1819 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1820 /* are_GC_task_threads */true,
1821 /* are_ConcurrentGC_threads */false);
1822 _workers->initialize_workers();
1823
1824 _allocator = G1Allocator::create_allocator(this);
1825 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1826
1827 // Override the default _filler_array_max_size so that no humongous filler
1828 // objects are created.
1829 _filler_array_max_size = _humongous_object_threshold_in_words;
1830
1831 uint n_queues = ParallelGCThreads;
1832 _task_queues = new RefToScanQueueSet(n_queues);
1833
1834 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1835 assert(n_rem_sets > 0, "Invariant.");
1836
1837 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1838 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1839 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1840
1841 for (uint i = 0; i < n_queues; i++) {
1842 RefToScanQueue* q = new RefToScanQueue();
1843 q->initialize();
1844 _task_queues->register_queue(i, q);
1845 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1846 }
1847 clear_cset_start_regions();
1848
1849 // Initialize the G1EvacuationFailureALot counters and flags.
1850 NOT_PRODUCT(reset_evacuation_should_fail();)
1851
1852 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1853 }
1854
1855 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1856 size_t size,
1857 size_t translation_factor) {
1858 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1859 // Allocate a new reserved space, preferring to use large pages.
1860 ReservedSpace rs(size, preferred_page_size);
1861 G1RegionToSpaceMapper* result =
1862 G1RegionToSpaceMapper::create_mapper(rs,
1863 size,
1864 rs.alignment(),
1865 HeapRegion::GrainBytes,
1866 translation_factor,
1867 mtGC);
1868 if (TracePageSizes) {
1869 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1870 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1871 }
1872 return result;
1873 }
1874
1875 jint G1CollectedHeap::initialize() {
1876 CollectedHeap::pre_initialize();
1877 os::enable_vtime();
1878
1879 G1Log::init();
1880
1881 // Necessary to satisfy locking discipline assertions.
1882
1883 MutexLocker x(Heap_lock);
1884
1885 // We have to initialize the printer before committing the heap, as
1886 // it will be used then.
1887 _hr_printer.set_active(G1PrintHeapRegions);
1888
1889 // While there are no constraints in the GC code that HeapWordSize
1890 // be any particular value, there are multiple other areas in the
1891 // system which believe this to be true (e.g. oop->object_size in some
1892 // cases incorrectly returns the size in wordSize units rather than
1893 // HeapWordSize).
1894 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1895
1896 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1897 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1898 size_t heap_alignment = collector_policy()->heap_alignment();
1899
1900 // Ensure that the sizes are properly aligned.
1901 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1902 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1903 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1904
1905 _refine_cte_cl = new RefineCardTableEntryClosure();
1906
1907 jint ecode = JNI_OK;
1908 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1909 if (_cg1r == NULL) {
1910 return ecode;
1911 }
1912
1913 // Reserve the maximum.
1914
1915 // When compressed oops are enabled, the preferred heap base
1916 // is calculated by subtracting the requested size from the
1917 // 32Gb boundary and using the result as the base address for
1918 // heap reservation. If the requested size is not aligned to
1919 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1920 // into the ReservedHeapSpace constructor) then the actual
1921 // base of the reserved heap may end up differing from the
1922 // address that was requested (i.e. the preferred heap base).
1923 // If this happens then we could end up using a non-optimal
1924 // compressed oops mode.
1925
1926 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1927 heap_alignment);
1928
1929 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1930
1931 // Create the barrier set for the entire reserved region.
1932 G1SATBCardTableLoggingModRefBS* bs
1933 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1934 bs->initialize();
1935 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1936 set_barrier_set(bs);
1937
1938 // Also create a G1 rem set.
1939 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1940
1941 // Carve out the G1 part of the heap.
1942
1943 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1944 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1945 G1RegionToSpaceMapper* heap_storage =
1946 G1RegionToSpaceMapper::create_mapper(g1_rs,
1947 g1_rs.size(),
1948 page_size,
1949 HeapRegion::GrainBytes,
1950 1,
1951 mtJavaHeap);
1952 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1953 max_byte_size, page_size,
1954 heap_rs.base(),
1955 heap_rs.size());
1956 heap_storage->set_mapping_changed_listener(&_listener);
1957
1958 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1959 G1RegionToSpaceMapper* bot_storage =
1960 create_aux_memory_mapper("Block offset table",
1961 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1962 G1BlockOffsetSharedArray::heap_map_factor());
1963
1964 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1965 G1RegionToSpaceMapper* cardtable_storage =
1966 create_aux_memory_mapper("Card table",
1967 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1968 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1969
1970 G1RegionToSpaceMapper* card_counts_storage =
1971 create_aux_memory_mapper("Card counts table",
1972 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1973 G1CardCounts::heap_map_factor());
1974
1975 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1976 G1RegionToSpaceMapper* prev_bitmap_storage =
1977 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1978 G1RegionToSpaceMapper* next_bitmap_storage =
1979 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1980
1981 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1982 g1_barrier_set()->initialize(cardtable_storage);
1983 // Do later initialization work for concurrent refinement.
1984 _cg1r->init(card_counts_storage);
1985
1986 // 6843694 - ensure that the maximum region index can fit
1987 // in the remembered set structures.
1988 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1989 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1990
1991 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1992 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1993 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1994 "too many cards per region");
1995
1996 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1997
1998 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1999
2000 {
2001 HeapWord* start = _hrm.reserved().start();
2002 HeapWord* end = _hrm.reserved().end();
2003 size_t granularity = HeapRegion::GrainBytes;
2004
2005 _in_cset_fast_test.initialize(start, end, granularity);
2006 _humongous_reclaim_candidates.initialize(start, end, granularity);
2007 }
2008
2009 // Create the ConcurrentMark data structure and thread.
2010 // (Must do this late, so that "max_regions" is defined.)
2011 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2012 if (_cm == NULL || !_cm->completed_initialization()) {
2013 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2014 return JNI_ENOMEM;
2015 }
2016 _cmThread = _cm->cmThread();
2017
2018 // Initialize the from_card cache structure of HeapRegionRemSet.
2019 HeapRegionRemSet::init_heap(max_regions());
2020
2021 // Now expand into the initial heap size.
2022 if (!expand(init_byte_size)) {
2023 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2024 return JNI_ENOMEM;
2025 }
2026
2027 // Perform any initialization actions delegated to the policy.
2028 g1_policy()->init();
2029
2030 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2031 SATB_Q_FL_lock,
2032 G1SATBProcessCompletedThreshold,
2033 Shared_SATB_Q_lock);
2034
2035 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2036 DirtyCardQ_CBL_mon,
2037 DirtyCardQ_FL_lock,
2038 concurrent_g1_refine()->yellow_zone(),
2039 concurrent_g1_refine()->red_zone(),
2040 Shared_DirtyCardQ_lock);
2041
2042 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2043 DirtyCardQ_CBL_mon,
2044 DirtyCardQ_FL_lock,
2045 -1, // never trigger processing
2046 -1, // no limit on length
2047 Shared_DirtyCardQ_lock,
2048 &JavaThread::dirty_card_queue_set());
2049
2050 // Here we allocate the dummy HeapRegion that is required by the
2051 // G1AllocRegion class.
2052 HeapRegion* dummy_region = _hrm.get_dummy_region();
2053
2054 // We'll re-use the same region whether the alloc region will
2055 // require BOT updates or not and, if it doesn't, then a non-young
2056 // region will complain that it cannot support allocations without
2057 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2058 dummy_region->set_eden();
2059 // Make sure it's full.
2060 dummy_region->set_top(dummy_region->end());
2061 G1AllocRegion::setup(this, dummy_region);
2062
2063 _allocator->init_mutator_alloc_region();
2064
2065 // Do create of the monitoring and management support so that
2066 // values in the heap have been properly initialized.
2067 _g1mm = new G1MonitoringSupport(this);
2068
2069 G1StringDedup::initialize();
2070
2071 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2072 for (uint i = 0; i < ParallelGCThreads; i++) {
2073 new (&_preserved_objs[i]) OopAndMarkOopStack();
2074 }
2075
2076 return JNI_OK;
2077 }
2078
2079 void G1CollectedHeap::stop() {
2080 // Stop all concurrent threads. We do this to make sure these threads
2081 // do not continue to execute and access resources (e.g. gclog_or_tty)
2082 // that are destroyed during shutdown.
2083 _cg1r->stop();
2084 _cmThread->stop();
2085 if (G1StringDedup::is_enabled()) {
2086 G1StringDedup::stop();
2087 }
2088 }
2089
2090 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2091 return HeapRegion::max_region_size();
2092 }
2093
2094 void G1CollectedHeap::post_initialize() {
2095 CollectedHeap::post_initialize();
2096 ref_processing_init();
2097 }
2098
2099 void G1CollectedHeap::ref_processing_init() {
2100 // Reference processing in G1 currently works as follows:
2101 //
2102 // * There are two reference processor instances. One is
2103 // used to record and process discovered references
2104 // during concurrent marking; the other is used to
2105 // record and process references during STW pauses
2106 // (both full and incremental).
2107 // * Both ref processors need to 'span' the entire heap as
2108 // the regions in the collection set may be dotted around.
2109 //
2110 // * For the concurrent marking ref processor:
2111 // * Reference discovery is enabled at initial marking.
2112 // * Reference discovery is disabled and the discovered
2113 // references processed etc during remarking.
2114 // * Reference discovery is MT (see below).
2115 // * Reference discovery requires a barrier (see below).
2116 // * Reference processing may or may not be MT
2117 // (depending on the value of ParallelRefProcEnabled
2118 // and ParallelGCThreads).
2119 // * A full GC disables reference discovery by the CM
2120 // ref processor and abandons any entries on it's
2121 // discovered lists.
2122 //
2123 // * For the STW processor:
2124 // * Non MT discovery is enabled at the start of a full GC.
2125 // * Processing and enqueueing during a full GC is non-MT.
2126 // * During a full GC, references are processed after marking.
2127 //
2128 // * Discovery (may or may not be MT) is enabled at the start
2129 // of an incremental evacuation pause.
2130 // * References are processed near the end of a STW evacuation pause.
2131 // * For both types of GC:
2132 // * Discovery is atomic - i.e. not concurrent.
2133 // * Reference discovery will not need a barrier.
2134
2135 MemRegion mr = reserved_region();
2136
2137 // Concurrent Mark ref processor
2138 _ref_processor_cm =
2139 new ReferenceProcessor(mr, // span
2140 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2141 // mt processing
2142 ParallelGCThreads,
2143 // degree of mt processing
2144 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2145 // mt discovery
2146 MAX2(ParallelGCThreads, ConcGCThreads),
2147 // degree of mt discovery
2148 false,
2149 // Reference discovery is not atomic
2150 &_is_alive_closure_cm);
2151 // is alive closure
2152 // (for efficiency/performance)
2153
2154 // STW ref processor
2155 _ref_processor_stw =
2156 new ReferenceProcessor(mr, // span
2157 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2158 // mt processing
2159 ParallelGCThreads,
2160 // degree of mt processing
2161 (ParallelGCThreads > 1),
2162 // mt discovery
2163 ParallelGCThreads,
2164 // degree of mt discovery
2165 true,
2166 // Reference discovery is atomic
2167 &_is_alive_closure_stw);
2168 // is alive closure
2169 // (for efficiency/performance)
2170 }
2171
2172 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2173 return g1_policy();
2174 }
2175
2176 size_t G1CollectedHeap::capacity() const {
2177 return _hrm.length() * HeapRegion::GrainBytes;
2178 }
2179
2180 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2181 hr->reset_gc_time_stamp();
2182 }
2183
2184 #ifndef PRODUCT
2185
2186 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2187 private:
2188 unsigned _gc_time_stamp;
2189 bool _failures;
2190
2191 public:
2192 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2193 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2194
2195 virtual bool doHeapRegion(HeapRegion* hr) {
2196 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2197 if (_gc_time_stamp != region_gc_time_stamp) {
2198 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2199 "expected %d", HR_FORMAT_PARAMS(hr),
2200 region_gc_time_stamp, _gc_time_stamp);
2201 _failures = true;
2202 }
2203 return false;
2204 }
2205
2206 bool failures() { return _failures; }
2207 };
2208
2209 void G1CollectedHeap::check_gc_time_stamps() {
2210 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2211 heap_region_iterate(&cl);
2212 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2213 }
2214 #endif // PRODUCT
2215
2216 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2217 _cg1r->hot_card_cache()->drain(cl, worker_i);
2218 }
2219
2220 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2221 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2222 size_t n_completed_buffers = 0;
2223 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2224 n_completed_buffers++;
2225 }
2226 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2227 dcqs.clear_n_completed_buffers();
2228 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2229 }
2230
2231 // Computes the sum of the storage used by the various regions.
2232 size_t G1CollectedHeap::used() const {
2233 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2234 if (_archive_allocator != NULL) {
2235 result += _archive_allocator->used();
2236 }
2237 return result;
2238 }
2239
2240 size_t G1CollectedHeap::used_unlocked() const {
2241 return _summary_bytes_used;
2242 }
2243
2244 class SumUsedClosure: public HeapRegionClosure {
2245 size_t _used;
2246 public:
2247 SumUsedClosure() : _used(0) {}
2248 bool doHeapRegion(HeapRegion* r) {
2249 _used += r->used();
2250 return false;
2251 }
2252 size_t result() { return _used; }
2253 };
2254
2255 size_t G1CollectedHeap::recalculate_used() const {
2256 double recalculate_used_start = os::elapsedTime();
2257
2258 SumUsedClosure blk;
2259 heap_region_iterate(&blk);
2260
2261 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2262 return blk.result();
2263 }
2264
2265 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2266 switch (cause) {
2267 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2268 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2269 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2270 case GCCause::_g1_humongous_allocation: return true;
2271 case GCCause::_update_allocation_context_stats_inc: return true;
2272 case GCCause::_wb_conc_mark: return true;
2273 default: return false;
2274 }
2275 }
2276
2277 #ifndef PRODUCT
2278 void G1CollectedHeap::allocate_dummy_regions() {
2279 // Let's fill up most of the region
2280 size_t word_size = HeapRegion::GrainWords - 1024;
2281 // And as a result the region we'll allocate will be humongous.
2282 guarantee(is_humongous(word_size), "sanity");
2283
2284 // _filler_array_max_size is set to humongous object threshold
2285 // but temporarily change it to use CollectedHeap::fill_with_object().
2286 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2287
2288 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2289 // Let's use the existing mechanism for the allocation
2290 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2291 AllocationContext::system());
2292 if (dummy_obj != NULL) {
2293 MemRegion mr(dummy_obj, word_size);
2294 CollectedHeap::fill_with_object(mr);
2295 } else {
2296 // If we can't allocate once, we probably cannot allocate
2297 // again. Let's get out of the loop.
2298 break;
2299 }
2300 }
2301 }
2302 #endif // !PRODUCT
2303
2304 void G1CollectedHeap::increment_old_marking_cycles_started() {
2305 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2306 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2307 "Wrong marking cycle count (started: %d, completed: %d)",
2308 _old_marking_cycles_started, _old_marking_cycles_completed);
2309
2310 _old_marking_cycles_started++;
2311 }
2312
2313 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2314 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2315
2316 // We assume that if concurrent == true, then the caller is a
2317 // concurrent thread that was joined the Suspendible Thread
2318 // Set. If there's ever a cheap way to check this, we should add an
2319 // assert here.
2320
2321 // Given that this method is called at the end of a Full GC or of a
2322 // concurrent cycle, and those can be nested (i.e., a Full GC can
2323 // interrupt a concurrent cycle), the number of full collections
2324 // completed should be either one (in the case where there was no
2325 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2326 // behind the number of full collections started.
2327
2328 // This is the case for the inner caller, i.e. a Full GC.
2329 assert(concurrent ||
2330 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2331 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2332 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2333 "is inconsistent with _old_marking_cycles_completed = %u",
2334 _old_marking_cycles_started, _old_marking_cycles_completed);
2335
2336 // This is the case for the outer caller, i.e. the concurrent cycle.
2337 assert(!concurrent ||
2338 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2339 "for outer caller (concurrent cycle): "
2340 "_old_marking_cycles_started = %u "
2341 "is inconsistent with _old_marking_cycles_completed = %u",
2342 _old_marking_cycles_started, _old_marking_cycles_completed);
2343
2344 _old_marking_cycles_completed += 1;
2345
2346 // We need to clear the "in_progress" flag in the CM thread before
2347 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2348 // is set) so that if a waiter requests another System.gc() it doesn't
2349 // incorrectly see that a marking cycle is still in progress.
2350 if (concurrent) {
2351 _cmThread->set_idle();
2352 }
2353
2354 // This notify_all() will ensure that a thread that called
2355 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2356 // and it's waiting for a full GC to finish will be woken up. It is
2357 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2358 FullGCCount_lock->notify_all();
2359 }
2360
2361 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2362 GCIdMarkAndRestore conc_gc_id_mark;
2363 collector_state()->set_concurrent_cycle_started(true);
2364 _gc_timer_cm->register_gc_start(start_time);
2365
2366 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2367 trace_heap_before_gc(_gc_tracer_cm);
2368 _cmThread->set_gc_id(GCId::current());
2369 }
2370
2371 void G1CollectedHeap::register_concurrent_cycle_end() {
2372 if (collector_state()->concurrent_cycle_started()) {
2373 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2374 if (_cm->has_aborted()) {
2375 _gc_tracer_cm->report_concurrent_mode_failure();
2376 }
2377
2378 _gc_timer_cm->register_gc_end();
2379 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2380
2381 // Clear state variables to prepare for the next concurrent cycle.
2382 collector_state()->set_concurrent_cycle_started(false);
2383 _heap_summary_sent = false;
2384 }
2385 }
2386
2387 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2388 if (collector_state()->concurrent_cycle_started()) {
2389 // This function can be called when:
2390 // the cleanup pause is run
2391 // the concurrent cycle is aborted before the cleanup pause.
2392 // the concurrent cycle is aborted after the cleanup pause,
2393 // but before the concurrent cycle end has been registered.
2394 // Make sure that we only send the heap information once.
2395 if (!_heap_summary_sent) {
2396 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2397 trace_heap_after_gc(_gc_tracer_cm);
2398 _heap_summary_sent = true;
2399 }
2400 }
2401 }
2402
2403 void G1CollectedHeap::collect(GCCause::Cause cause) {
2404 assert_heap_not_locked();
2405
2406 uint gc_count_before;
2407 uint old_marking_count_before;
2408 uint full_gc_count_before;
2409 bool retry_gc;
2410
2411 do {
2412 retry_gc = false;
2413
2414 {
2415 MutexLocker ml(Heap_lock);
2416
2417 // Read the GC count while holding the Heap_lock
2418 gc_count_before = total_collections();
2419 full_gc_count_before = total_full_collections();
2420 old_marking_count_before = _old_marking_cycles_started;
2421 }
2422
2423 if (should_do_concurrent_full_gc(cause)) {
2424 // Schedule an initial-mark evacuation pause that will start a
2425 // concurrent cycle. We're setting word_size to 0 which means that
2426 // we are not requesting a post-GC allocation.
2427 VM_G1IncCollectionPause op(gc_count_before,
2428 0, /* word_size */
2429 true, /* should_initiate_conc_mark */
2430 g1_policy()->max_pause_time_ms(),
2431 cause);
2432 op.set_allocation_context(AllocationContext::current());
2433
2434 VMThread::execute(&op);
2435 if (!op.pause_succeeded()) {
2436 if (old_marking_count_before == _old_marking_cycles_started) {
2437 retry_gc = op.should_retry_gc();
2438 } else {
2439 // A Full GC happened while we were trying to schedule the
2440 // initial-mark GC. No point in starting a new cycle given
2441 // that the whole heap was collected anyway.
2442 }
2443
2444 if (retry_gc) {
2445 if (GC_locker::is_active_and_needs_gc()) {
2446 GC_locker::stall_until_clear();
2447 }
2448 }
2449 }
2450 } else {
2451 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2452 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2453
2454 // Schedule a standard evacuation pause. We're setting word_size
2455 // to 0 which means that we are not requesting a post-GC allocation.
2456 VM_G1IncCollectionPause op(gc_count_before,
2457 0, /* word_size */
2458 false, /* should_initiate_conc_mark */
2459 g1_policy()->max_pause_time_ms(),
2460 cause);
2461 VMThread::execute(&op);
2462 } else {
2463 // Schedule a Full GC.
2464 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2465 VMThread::execute(&op);
2466 }
2467 }
2468 } while (retry_gc);
2469 }
2470
2471 bool G1CollectedHeap::is_in(const void* p) const {
2472 if (_hrm.reserved().contains(p)) {
2473 // Given that we know that p is in the reserved space,
2474 // heap_region_containing() should successfully
2475 // return the containing region.
2476 HeapRegion* hr = heap_region_containing(p);
2477 return hr->is_in(p);
2478 } else {
2479 return false;
2480 }
2481 }
2482
2483 #ifdef ASSERT
2484 bool G1CollectedHeap::is_in_exact(const void* p) const {
2485 bool contains = reserved_region().contains(p);
2486 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2487 if (contains && available) {
2488 return true;
2489 } else {
2490 return false;
2491 }
2492 }
2493 #endif
2494
2495 bool G1CollectedHeap::obj_in_cs(oop obj) {
2496 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2497 return r != NULL && r->in_collection_set();
2498 }
2499
2500 // Iteration functions.
2501
2502 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2503
2504 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2505 ExtendedOopClosure* _cl;
2506 public:
2507 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2508 bool doHeapRegion(HeapRegion* r) {
2509 if (!r->is_continues_humongous()) {
2510 r->oop_iterate(_cl);
2511 }
2512 return false;
2513 }
2514 };
2515
2516 // Iterates an ObjectClosure over all objects within a HeapRegion.
2517
2518 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2519 ObjectClosure* _cl;
2520 public:
2521 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2522 bool doHeapRegion(HeapRegion* r) {
2523 if (!r->is_continues_humongous()) {
2524 r->object_iterate(_cl);
2525 }
2526 return false;
2527 }
2528 };
2529
2530 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2531 IterateObjectClosureRegionClosure blk(cl);
2532 heap_region_iterate(&blk);
2533 }
2534
2535 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2536 _hrm.iterate(cl);
2537 }
2538
2539 void
2540 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2541 uint worker_id,
2542 HeapRegionClaimer *hrclaimer,
2543 bool concurrent) const {
2544 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2545 }
2546
2547 // Clear the cached CSet starting regions and (more importantly)
2548 // the time stamps. Called when we reset the GC time stamp.
2549 void G1CollectedHeap::clear_cset_start_regions() {
2550 assert(_worker_cset_start_region != NULL, "sanity");
2551 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2552
2553 for (uint i = 0; i < ParallelGCThreads; i++) {
2554 _worker_cset_start_region[i] = NULL;
2555 _worker_cset_start_region_time_stamp[i] = 0;
2556 }
2557 }
2558
2559 // Given the id of a worker, obtain or calculate a suitable
2560 // starting region for iterating over the current collection set.
2561 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2562 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2563
2564 HeapRegion* result = NULL;
2565 unsigned gc_time_stamp = get_gc_time_stamp();
2566
2567 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2568 // Cached starting region for current worker was set
2569 // during the current pause - so it's valid.
2570 // Note: the cached starting heap region may be NULL
2571 // (when the collection set is empty).
2572 result = _worker_cset_start_region[worker_i];
2573 assert(result == NULL || result->in_collection_set(), "sanity");
2574 return result;
2575 }
2576
2577 // The cached entry was not valid so let's calculate
2578 // a suitable starting heap region for this worker.
2579
2580 // We want the parallel threads to start their collection
2581 // set iteration at different collection set regions to
2582 // avoid contention.
2583 // If we have:
2584 // n collection set regions
2585 // p threads
2586 // Then thread t will start at region floor ((t * n) / p)
2587
2588 result = g1_policy()->collection_set();
2589 uint cs_size = g1_policy()->cset_region_length();
2590 uint active_workers = workers()->active_workers();
2591
2592 uint end_ind = (cs_size * worker_i) / active_workers;
2593 uint start_ind = 0;
2594
2595 if (worker_i > 0 &&
2596 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2597 // Previous workers starting region is valid
2598 // so let's iterate from there
2599 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2600 result = _worker_cset_start_region[worker_i - 1];
2601 }
2602
2603 for (uint i = start_ind; i < end_ind; i++) {
2604 result = result->next_in_collection_set();
2605 }
2606
2607 // Note: the calculated starting heap region may be NULL
2608 // (when the collection set is empty).
2609 assert(result == NULL || result->in_collection_set(), "sanity");
2610 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2611 "should be updated only once per pause");
2612 _worker_cset_start_region[worker_i] = result;
2613 OrderAccess::storestore();
2614 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2615 return result;
2616 }
2617
2618 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2619 HeapRegion* r = g1_policy()->collection_set();
2620 while (r != NULL) {
2621 HeapRegion* next = r->next_in_collection_set();
2622 if (cl->doHeapRegion(r)) {
2623 cl->incomplete();
2624 return;
2625 }
2626 r = next;
2627 }
2628 }
2629
2630 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2631 HeapRegionClosure *cl) {
2632 if (r == NULL) {
2633 // The CSet is empty so there's nothing to do.
2634 return;
2635 }
2636
2637 assert(r->in_collection_set(),
2638 "Start region must be a member of the collection set.");
2639 HeapRegion* cur = r;
2640 while (cur != NULL) {
2641 HeapRegion* next = cur->next_in_collection_set();
2642 if (cl->doHeapRegion(cur) && false) {
2643 cl->incomplete();
2644 return;
2645 }
2646 cur = next;
2647 }
2648 cur = g1_policy()->collection_set();
2649 while (cur != r) {
2650 HeapRegion* next = cur->next_in_collection_set();
2651 if (cl->doHeapRegion(cur) && false) {
2652 cl->incomplete();
2653 return;
2654 }
2655 cur = next;
2656 }
2657 }
2658
2659 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2660 HeapRegion* result = _hrm.next_region_in_heap(from);
2661 while (result != NULL && result->is_pinned()) {
2662 result = _hrm.next_region_in_heap(result);
2663 }
2664 return result;
2665 }
2666
2667 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2668 HeapRegion* hr = heap_region_containing(addr);
2669 return hr->block_start(addr);
2670 }
2671
2672 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2673 HeapRegion* hr = heap_region_containing(addr);
2674 return hr->block_size(addr);
2675 }
2676
2677 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2678 HeapRegion* hr = heap_region_containing(addr);
2679 return hr->block_is_obj(addr);
2680 }
2681
2682 bool G1CollectedHeap::supports_tlab_allocation() const {
2683 return true;
2684 }
2685
2686 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2687 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2688 }
2689
2690 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2691 return young_list()->eden_used_bytes();
2692 }
2693
2694 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2695 // must be equal to the humongous object limit.
2696 size_t G1CollectedHeap::max_tlab_size() const {
2697 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2698 }
2699
2700 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2701 AllocationContext_t context = AllocationContext::current();
2702 return _allocator->unsafe_max_tlab_alloc(context);
2703 }
2704
2705 size_t G1CollectedHeap::max_capacity() const {
2706 return _hrm.reserved().byte_size();
2707 }
2708
2709 jlong G1CollectedHeap::millis_since_last_gc() {
2710 // assert(false, "NYI");
2711 return 0;
2712 }
2713
2714 void G1CollectedHeap::prepare_for_verify() {
2715 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2716 ensure_parsability(false);
2717 }
2718 g1_rem_set()->prepare_for_verify();
2719 }
2720
2721 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2722 VerifyOption vo) {
2723 switch (vo) {
2724 case VerifyOption_G1UsePrevMarking:
2725 return hr->obj_allocated_since_prev_marking(obj);
2726 case VerifyOption_G1UseNextMarking:
2727 return hr->obj_allocated_since_next_marking(obj);
2728 case VerifyOption_G1UseMarkWord:
2729 return false;
2730 default:
2731 ShouldNotReachHere();
2732 }
2733 return false; // keep some compilers happy
2734 }
2735
2736 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2737 switch (vo) {
2738 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2739 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2740 case VerifyOption_G1UseMarkWord: return NULL;
2741 default: ShouldNotReachHere();
2742 }
2743 return NULL; // keep some compilers happy
2744 }
2745
2746 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2747 switch (vo) {
2748 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2749 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2750 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2751 default: ShouldNotReachHere();
2752 }
2753 return false; // keep some compilers happy
2754 }
2755
2756 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2757 switch (vo) {
2758 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2759 case VerifyOption_G1UseNextMarking: return "NTAMS";
2760 case VerifyOption_G1UseMarkWord: return "NONE";
2761 default: ShouldNotReachHere();
2762 }
2763 return NULL; // keep some compilers happy
2764 }
2765
2766 class VerifyRootsClosure: public OopClosure {
2767 private:
2768 G1CollectedHeap* _g1h;
2769 VerifyOption _vo;
2770 bool _failures;
2771 public:
2772 // _vo == UsePrevMarking -> use "prev" marking information,
2773 // _vo == UseNextMarking -> use "next" marking information,
2774 // _vo == UseMarkWord -> use mark word from object header.
2775 VerifyRootsClosure(VerifyOption vo) :
2776 _g1h(G1CollectedHeap::heap()),
2777 _vo(vo),
2778 _failures(false) { }
2779
2780 bool failures() { return _failures; }
2781
2782 template <class T> void do_oop_nv(T* p) {
2783 T heap_oop = oopDesc::load_heap_oop(p);
2784 if (!oopDesc::is_null(heap_oop)) {
2785 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2786 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2787 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2788 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2789 if (_vo == VerifyOption_G1UseMarkWord) {
2790 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2791 }
2792 obj->print_on(gclog_or_tty);
2793 _failures = true;
2794 }
2795 }
2796 }
2797
2798 void do_oop(oop* p) { do_oop_nv(p); }
2799 void do_oop(narrowOop* p) { do_oop_nv(p); }
2800 };
2801
2802 class G1VerifyCodeRootOopClosure: public OopClosure {
2803 G1CollectedHeap* _g1h;
2804 OopClosure* _root_cl;
2805 nmethod* _nm;
2806 VerifyOption _vo;
2807 bool _failures;
2808
2809 template <class T> void do_oop_work(T* p) {
2810 // First verify that this root is live
2811 _root_cl->do_oop(p);
2812
2813 if (!G1VerifyHeapRegionCodeRoots) {
2814 // We're not verifying the code roots attached to heap region.
2815 return;
2816 }
2817
2818 // Don't check the code roots during marking verification in a full GC
2819 if (_vo == VerifyOption_G1UseMarkWord) {
2820 return;
2821 }
2822
2823 // Now verify that the current nmethod (which contains p) is
2824 // in the code root list of the heap region containing the
2825 // object referenced by p.
2826
2827 T heap_oop = oopDesc::load_heap_oop(p);
2828 if (!oopDesc::is_null(heap_oop)) {
2829 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2830
2831 // Now fetch the region containing the object
2832 HeapRegion* hr = _g1h->heap_region_containing(obj);
2833 HeapRegionRemSet* hrrs = hr->rem_set();
2834 // Verify that the strong code root list for this region
2835 // contains the nmethod
2836 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2837 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2838 "from nmethod " PTR_FORMAT " not in strong "
2839 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2840 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2841 _failures = true;
2842 }
2843 }
2844 }
2845
2846 public:
2847 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2848 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2849
2850 void do_oop(oop* p) { do_oop_work(p); }
2851 void do_oop(narrowOop* p) { do_oop_work(p); }
2852
2853 void set_nmethod(nmethod* nm) { _nm = nm; }
2854 bool failures() { return _failures; }
2855 };
2856
2857 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2858 G1VerifyCodeRootOopClosure* _oop_cl;
2859
2860 public:
2861 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2862 _oop_cl(oop_cl) {}
2863
2864 void do_code_blob(CodeBlob* cb) {
2865 nmethod* nm = cb->as_nmethod_or_null();
2866 if (nm != NULL) {
2867 _oop_cl->set_nmethod(nm);
2868 nm->oops_do(_oop_cl);
2869 }
2870 }
2871 };
2872
2873 class YoungRefCounterClosure : public OopClosure {
2874 G1CollectedHeap* _g1h;
2875 int _count;
2876 public:
2877 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2878 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2879 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2880
2881 int count() { return _count; }
2882 void reset_count() { _count = 0; };
2883 };
2884
2885 class VerifyKlassClosure: public KlassClosure {
2886 YoungRefCounterClosure _young_ref_counter_closure;
2887 OopClosure *_oop_closure;
2888 public:
2889 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2890 void do_klass(Klass* k) {
2891 k->oops_do(_oop_closure);
2892
2893 _young_ref_counter_closure.reset_count();
2894 k->oops_do(&_young_ref_counter_closure);
2895 if (_young_ref_counter_closure.count() > 0) {
2896 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2897 }
2898 }
2899 };
2900
2901 class VerifyLivenessOopClosure: public OopClosure {
2902 G1CollectedHeap* _g1h;
2903 VerifyOption _vo;
2904 public:
2905 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2906 _g1h(g1h), _vo(vo)
2907 { }
2908 void do_oop(narrowOop *p) { do_oop_work(p); }
2909 void do_oop( oop *p) { do_oop_work(p); }
2910
2911 template <class T> void do_oop_work(T *p) {
2912 oop obj = oopDesc::load_decode_heap_oop(p);
2913 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2914 "Dead object referenced by a not dead object");
2915 }
2916 };
2917
2918 class VerifyObjsInRegionClosure: public ObjectClosure {
2919 private:
2920 G1CollectedHeap* _g1h;
2921 size_t _live_bytes;
2922 HeapRegion *_hr;
2923 VerifyOption _vo;
2924 public:
2925 // _vo == UsePrevMarking -> use "prev" marking information,
2926 // _vo == UseNextMarking -> use "next" marking information,
2927 // _vo == UseMarkWord -> use mark word from object header.
2928 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2929 : _live_bytes(0), _hr(hr), _vo(vo) {
2930 _g1h = G1CollectedHeap::heap();
2931 }
2932 void do_object(oop o) {
2933 VerifyLivenessOopClosure isLive(_g1h, _vo);
2934 assert(o != NULL, "Huh?");
2935 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2936 // If the object is alive according to the mark word,
2937 // then verify that the marking information agrees.
2938 // Note we can't verify the contra-positive of the
2939 // above: if the object is dead (according to the mark
2940 // word), it may not be marked, or may have been marked
2941 // but has since became dead, or may have been allocated
2942 // since the last marking.
2943 if (_vo == VerifyOption_G1UseMarkWord) {
2944 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2945 }
2946
2947 o->oop_iterate_no_header(&isLive);
2948 if (!_hr->obj_allocated_since_prev_marking(o)) {
2949 size_t obj_size = o->size(); // Make sure we don't overflow
2950 _live_bytes += (obj_size * HeapWordSize);
2951 }
2952 }
2953 }
2954 size_t live_bytes() { return _live_bytes; }
2955 };
2956
2957 class VerifyArchiveOopClosure: public OopClosure {
2958 public:
2959 VerifyArchiveOopClosure(HeapRegion *hr) { }
2960 void do_oop(narrowOop *p) { do_oop_work(p); }
2961 void do_oop( oop *p) { do_oop_work(p); }
2962
2963 template <class T> void do_oop_work(T *p) {
2964 oop obj = oopDesc::load_decode_heap_oop(p);
2965 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2966 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2967 p2i(p), p2i(obj));
2968 }
2969 };
2970
2971 class VerifyArchiveRegionClosure: public ObjectClosure {
2972 public:
2973 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2974 // Verify that all object pointers are to archive regions.
2975 void do_object(oop o) {
2976 VerifyArchiveOopClosure checkOop(NULL);
2977 assert(o != NULL, "Should not be here for NULL oops");
2978 o->oop_iterate_no_header(&checkOop);
2979 }
2980 };
2981
2982 class VerifyRegionClosure: public HeapRegionClosure {
2983 private:
2984 bool _par;
2985 VerifyOption _vo;
2986 bool _failures;
2987 public:
2988 // _vo == UsePrevMarking -> use "prev" marking information,
2989 // _vo == UseNextMarking -> use "next" marking information,
2990 // _vo == UseMarkWord -> use mark word from object header.
2991 VerifyRegionClosure(bool par, VerifyOption vo)
2992 : _par(par),
2993 _vo(vo),
2994 _failures(false) {}
2995
2996 bool failures() {
2997 return _failures;
2998 }
2999
3000 bool doHeapRegion(HeapRegion* r) {
3001 // For archive regions, verify there are no heap pointers to
3002 // non-pinned regions. For all others, verify liveness info.
3003 if (r->is_archive()) {
3004 VerifyArchiveRegionClosure verify_oop_pointers(r);
3005 r->object_iterate(&verify_oop_pointers);
3006 return true;
3007 }
3008 if (!r->is_continues_humongous()) {
3009 bool failures = false;
3010 r->verify(_vo, &failures);
3011 if (failures) {
3012 _failures = true;
3013 } else if (!r->is_starts_humongous()) {
3014 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3015 r->object_iterate(¬_dead_yet_cl);
3016 if (_vo != VerifyOption_G1UseNextMarking) {
3017 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3018 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3019 "max_live_bytes " SIZE_FORMAT " "
3020 "< calculated " SIZE_FORMAT,
3021 p2i(r->bottom()), p2i(r->end()),
3022 r->max_live_bytes(),
3023 not_dead_yet_cl.live_bytes());
3024 _failures = true;
3025 }
3026 } else {
3027 // When vo == UseNextMarking we cannot currently do a sanity
3028 // check on the live bytes as the calculation has not been
3029 // finalized yet.
3030 }
3031 }
3032 }
3033 return false; // stop the region iteration if we hit a failure
3034 }
3035 };
3036
3037 // This is the task used for parallel verification of the heap regions
3038
3039 class G1ParVerifyTask: public AbstractGangTask {
3040 private:
3041 G1CollectedHeap* _g1h;
3042 VerifyOption _vo;
3043 bool _failures;
3044 HeapRegionClaimer _hrclaimer;
3045
3046 public:
3047 // _vo == UsePrevMarking -> use "prev" marking information,
3048 // _vo == UseNextMarking -> use "next" marking information,
3049 // _vo == UseMarkWord -> use mark word from object header.
3050 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3051 AbstractGangTask("Parallel verify task"),
3052 _g1h(g1h),
3053 _vo(vo),
3054 _failures(false),
3055 _hrclaimer(g1h->workers()->active_workers()) {}
3056
3057 bool failures() {
3058 return _failures;
3059 }
3060
3061 void work(uint worker_id) {
3062 HandleMark hm;
3063 VerifyRegionClosure blk(true, _vo);
3064 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3065 if (blk.failures()) {
3066 _failures = true;
3067 }
3068 }
3069 };
3070
3071 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3072 if (SafepointSynchronize::is_at_safepoint()) {
3073 assert(Thread::current()->is_VM_thread(),
3074 "Expected to be executed serially by the VM thread at this point");
3075
3076 if (!silent) { gclog_or_tty->print("Roots "); }
3077 VerifyRootsClosure rootsCl(vo);
3078 VerifyKlassClosure klassCl(this, &rootsCl);
3079 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3080
3081 // We apply the relevant closures to all the oops in the
3082 // system dictionary, class loader data graph, the string table
3083 // and the nmethods in the code cache.
3084 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3085 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3086
3087 {
3088 G1RootProcessor root_processor(this, 1);
3089 root_processor.process_all_roots(&rootsCl,
3090 &cldCl,
3091 &blobsCl);
3092 }
3093
3094 bool failures = rootsCl.failures() || codeRootsCl.failures();
3095
3096 if (vo != VerifyOption_G1UseMarkWord) {
3097 // If we're verifying during a full GC then the region sets
3098 // will have been torn down at the start of the GC. Therefore
3099 // verifying the region sets will fail. So we only verify
3100 // the region sets when not in a full GC.
3101 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3102 verify_region_sets();
3103 }
3104
3105 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3106 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3107
3108 G1ParVerifyTask task(this, vo);
3109 workers()->run_task(&task);
3110 if (task.failures()) {
3111 failures = true;
3112 }
3113
3114 } else {
3115 VerifyRegionClosure blk(false, vo);
3116 heap_region_iterate(&blk);
3117 if (blk.failures()) {
3118 failures = true;
3119 }
3120 }
3121
3122 if (G1StringDedup::is_enabled()) {
3123 if (!silent) gclog_or_tty->print("StrDedup ");
3124 G1StringDedup::verify();
3125 }
3126
3127 if (failures) {
3128 gclog_or_tty->print_cr("Heap:");
3129 // It helps to have the per-region information in the output to
3130 // help us track down what went wrong. This is why we call
3131 // print_extended_on() instead of print_on().
3132 print_extended_on(gclog_or_tty);
3133 gclog_or_tty->cr();
3134 gclog_or_tty->flush();
3135 }
3136 guarantee(!failures, "there should not have been any failures");
3137 } else {
3138 if (!silent) {
3139 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3140 if (G1StringDedup::is_enabled()) {
3141 gclog_or_tty->print(", StrDedup");
3142 }
3143 gclog_or_tty->print(") ");
3144 }
3145 }
3146 }
3147
3148 void G1CollectedHeap::verify(bool silent) {
3149 verify(silent, VerifyOption_G1UsePrevMarking);
3150 }
3151
3152 double G1CollectedHeap::verify(bool guard, const char* msg) {
3153 double verify_time_ms = 0.0;
3154
3155 if (guard && total_collections() >= VerifyGCStartAt) {
3156 double verify_start = os::elapsedTime();
3157 HandleMark hm; // Discard invalid handles created during verification
3158 prepare_for_verify();
3159 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3160 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3161 }
3162
3163 return verify_time_ms;
3164 }
3165
3166 void G1CollectedHeap::verify_before_gc() {
3167 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3168 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3169 }
3170
3171 void G1CollectedHeap::verify_after_gc() {
3172 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3173 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3174 }
3175
3176 class PrintRegionClosure: public HeapRegionClosure {
3177 outputStream* _st;
3178 public:
3179 PrintRegionClosure(outputStream* st) : _st(st) {}
3180 bool doHeapRegion(HeapRegion* r) {
3181 r->print_on(_st);
3182 return false;
3183 }
3184 };
3185
3186 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3187 const HeapRegion* hr,
3188 const VerifyOption vo) const {
3189 switch (vo) {
3190 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3191 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3192 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3193 default: ShouldNotReachHere();
3194 }
3195 return false; // keep some compilers happy
3196 }
3197
3198 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3199 const VerifyOption vo) const {
3200 switch (vo) {
3201 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3202 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3203 case VerifyOption_G1UseMarkWord: {
3204 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3205 return !obj->is_gc_marked() && !hr->is_archive();
3206 }
3207 default: ShouldNotReachHere();
3208 }
3209 return false; // keep some compilers happy
3210 }
3211
3212 void G1CollectedHeap::print_on(outputStream* st) const {
3213 st->print(" %-20s", "garbage-first heap");
3214 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3215 capacity()/K, used_unlocked()/K);
3216 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3217 p2i(_hrm.reserved().start()),
3218 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3219 p2i(_hrm.reserved().end()));
3220 st->cr();
3221 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3222 uint young_regions = _young_list->length();
3223 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3224 (size_t) young_regions * HeapRegion::GrainBytes / K);
3225 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3226 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3227 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3228 st->cr();
3229 MetaspaceAux::print_on(st);
3230 }
3231
3232 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3233 print_on(st);
3234
3235 // Print the per-region information.
3236 st->cr();
3237 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3238 "HS=humongous(starts), HC=humongous(continues), "
3239 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3240 "PTAMS=previous top-at-mark-start, "
3241 "NTAMS=next top-at-mark-start)");
3242 PrintRegionClosure blk(st);
3243 heap_region_iterate(&blk);
3244 }
3245
3246 void G1CollectedHeap::print_on_error(outputStream* st) const {
3247 this->CollectedHeap::print_on_error(st);
3248
3249 if (_cm != NULL) {
3250 st->cr();
3251 _cm->print_on_error(st);
3252 }
3253 }
3254
3255 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3256 workers()->print_worker_threads_on(st);
3257 _cmThread->print_on(st);
3258 st->cr();
3259 _cm->print_worker_threads_on(st);
3260 _cg1r->print_worker_threads_on(st);
3261 if (G1StringDedup::is_enabled()) {
3262 G1StringDedup::print_worker_threads_on(st);
3263 }
3264 }
3265
3266 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3267 workers()->threads_do(tc);
3268 tc->do_thread(_cmThread);
3269 _cg1r->threads_do(tc);
3270 if (G1StringDedup::is_enabled()) {
3271 G1StringDedup::threads_do(tc);
3272 }
3273 }
3274
3275 void G1CollectedHeap::print_tracing_info() const {
3276 // We'll overload this to mean "trace GC pause statistics."
3277 if (TraceYoungGenTime || TraceOldGenTime) {
3278 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3279 // to that.
3280 g1_policy()->print_tracing_info();
3281 }
3282 if (G1SummarizeRSetStats) {
3283 g1_rem_set()->print_summary_info();
3284 }
3285 if (G1SummarizeConcMark) {
3286 concurrent_mark()->print_summary_info();
3287 }
3288 g1_policy()->print_yg_surv_rate_info();
3289 }
3290
3291 #ifndef PRODUCT
3292 // Helpful for debugging RSet issues.
3293
3294 class PrintRSetsClosure : public HeapRegionClosure {
3295 private:
3296 const char* _msg;
3297 size_t _occupied_sum;
3298
3299 public:
3300 bool doHeapRegion(HeapRegion* r) {
3301 HeapRegionRemSet* hrrs = r->rem_set();
3302 size_t occupied = hrrs->occupied();
3303 _occupied_sum += occupied;
3304
3305 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3306 HR_FORMAT_PARAMS(r));
3307 if (occupied == 0) {
3308 gclog_or_tty->print_cr(" RSet is empty");
3309 } else {
3310 hrrs->print();
3311 }
3312 gclog_or_tty->print_cr("----------");
3313 return false;
3314 }
3315
3316 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3317 gclog_or_tty->cr();
3318 gclog_or_tty->print_cr("========================================");
3319 gclog_or_tty->print_cr("%s", msg);
3320 gclog_or_tty->cr();
3321 }
3322
3323 ~PrintRSetsClosure() {
3324 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3325 gclog_or_tty->print_cr("========================================");
3326 gclog_or_tty->cr();
3327 }
3328 };
3329
3330 void G1CollectedHeap::print_cset_rsets() {
3331 PrintRSetsClosure cl("Printing CSet RSets");
3332 collection_set_iterate(&cl);
3333 }
3334
3335 void G1CollectedHeap::print_all_rsets() {
3336 PrintRSetsClosure cl("Printing All RSets");;
3337 heap_region_iterate(&cl);
3338 }
3339 #endif // PRODUCT
3340
3341 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3342 YoungList* young_list = heap()->young_list();
3343
3344 size_t eden_used_bytes = young_list->eden_used_bytes();
3345 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3346
3347 size_t eden_capacity_bytes =
3348 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3349
3350 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3351 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3352 }
3353
3354 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3355 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3356 stats->unused(), stats->used(), stats->region_end_waste(),
3357 stats->regions_filled(), stats->direct_allocated(),
3358 stats->failure_used(), stats->failure_waste());
3359 }
3360
3361 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3362 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3363 gc_tracer->report_gc_heap_summary(when, heap_summary);
3364
3365 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3366 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3367 }
3368
3369
3370 G1CollectedHeap* G1CollectedHeap::heap() {
3371 CollectedHeap* heap = Universe::heap();
3372 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3373 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3374 return (G1CollectedHeap*)heap;
3375 }
3376
3377 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3378 // always_do_update_barrier = false;
3379 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3380 // Fill TLAB's and such
3381 accumulate_statistics_all_tlabs();
3382 ensure_parsability(true);
3383
3384 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3385 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3386 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3387 }
3388 }
3389
3390 void G1CollectedHeap::gc_epilogue(bool full) {
3391
3392 if (G1SummarizeRSetStats &&
3393 (G1SummarizeRSetStatsPeriod > 0) &&
3394 // we are at the end of the GC. Total collections has already been increased.
3395 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3396 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3397 }
3398
3399 // FIXME: what is this about?
3400 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3401 // is set.
3402 #if defined(COMPILER2) || INCLUDE_JVMCI
3403 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3404 #endif
3405 // always_do_update_barrier = true;
3406
3407 resize_all_tlabs();
3408 allocation_context_stats().update(full);
3409
3410 // We have just completed a GC. Update the soft reference
3411 // policy with the new heap occupancy
3412 Universe::update_heap_info_at_gc();
3413 }
3414
3415 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3416 uint gc_count_before,
3417 bool* succeeded,
3418 GCCause::Cause gc_cause) {
3419 assert_heap_not_locked_and_not_at_safepoint();
3420 g1_policy()->record_stop_world_start();
3421 VM_G1IncCollectionPause op(gc_count_before,
3422 word_size,
3423 false, /* should_initiate_conc_mark */
3424 g1_policy()->max_pause_time_ms(),
3425 gc_cause);
3426
3427 op.set_allocation_context(AllocationContext::current());
3428 VMThread::execute(&op);
3429
3430 HeapWord* result = op.result();
3431 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3432 assert(result == NULL || ret_succeeded,
3433 "the result should be NULL if the VM did not succeed");
3434 *succeeded = ret_succeeded;
3435
3436 assert_heap_not_locked();
3437 return result;
3438 }
3439
3440 void
3441 G1CollectedHeap::doConcurrentMark() {
3442 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3443 if (!_cmThread->in_progress()) {
3444 _cmThread->set_started();
3445 CGC_lock->notify();
3446 }
3447 }
3448
3449 size_t G1CollectedHeap::pending_card_num() {
3450 size_t extra_cards = 0;
3451 JavaThread *curr = Threads::first();
3452 while (curr != NULL) {
3453 DirtyCardQueue& dcq = curr->dirty_card_queue();
3454 extra_cards += dcq.size();
3455 curr = curr->next();
3456 }
3457 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3458 size_t buffer_size = dcqs.buffer_size();
3459 size_t buffer_num = dcqs.completed_buffers_num();
3460
3461 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3462 // in bytes - not the number of 'entries'. We need to convert
3463 // into a number of cards.
3464 return (buffer_size * buffer_num + extra_cards) / oopSize;
3465 }
3466
3467 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3468 private:
3469 size_t _total_humongous;
3470 size_t _candidate_humongous;
3471
3472 DirtyCardQueue _dcq;
3473
3474 // We don't nominate objects with many remembered set entries, on
3475 // the assumption that such objects are likely still live.
3476 bool is_remset_small(HeapRegion* region) const {
3477 HeapRegionRemSet* const rset = region->rem_set();
3478 return G1EagerReclaimHumongousObjectsWithStaleRefs
3479 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3480 : rset->is_empty();
3481 }
3482
3483 bool is_typeArray_region(HeapRegion* region) const {
3484 return oop(region->bottom())->is_typeArray();
3485 }
3486
3487 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3488 assert(region->is_starts_humongous(), "Must start a humongous object");
3489
3490 // Candidate selection must satisfy the following constraints
3491 // while concurrent marking is in progress:
3492 //
3493 // * In order to maintain SATB invariants, an object must not be
3494 // reclaimed if it was allocated before the start of marking and
3495 // has not had its references scanned. Such an object must have
3496 // its references (including type metadata) scanned to ensure no
3497 // live objects are missed by the marking process. Objects
3498 // allocated after the start of concurrent marking don't need to
3499 // be scanned.
3500 //
3501 // * An object must not be reclaimed if it is on the concurrent
3502 // mark stack. Objects allocated after the start of concurrent
3503 // marking are never pushed on the mark stack.
3504 //
3505 // Nominating only objects allocated after the start of concurrent
3506 // marking is sufficient to meet both constraints. This may miss
3507 // some objects that satisfy the constraints, but the marking data
3508 // structures don't support efficiently performing the needed
3509 // additional tests or scrubbing of the mark stack.
3510 //
3511 // However, we presently only nominate is_typeArray() objects.
3512 // A humongous object containing references induces remembered
3513 // set entries on other regions. In order to reclaim such an
3514 // object, those remembered sets would need to be cleaned up.
3515 //
3516 // We also treat is_typeArray() objects specially, allowing them
3517 // to be reclaimed even if allocated before the start of
3518 // concurrent mark. For this we rely on mark stack insertion to
3519 // exclude is_typeArray() objects, preventing reclaiming an object
3520 // that is in the mark stack. We also rely on the metadata for
3521 // such objects to be built-in and so ensured to be kept live.
3522 // Frequent allocation and drop of large binary blobs is an
3523 // important use case for eager reclaim, and this special handling
3524 // may reduce needed headroom.
3525
3526 return is_typeArray_region(region) && is_remset_small(region);
3527 }
3528
3529 public:
3530 RegisterHumongousWithInCSetFastTestClosure()
3531 : _total_humongous(0),
3532 _candidate_humongous(0),
3533 _dcq(&JavaThread::dirty_card_queue_set()) {
3534 }
3535
3536 virtual bool doHeapRegion(HeapRegion* r) {
3537 if (!r->is_starts_humongous()) {
3538 return false;
3539 }
3540 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3541
3542 bool is_candidate = humongous_region_is_candidate(g1h, r);
3543 uint rindex = r->hrm_index();
3544 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3545 if (is_candidate) {
3546 _candidate_humongous++;
3547 g1h->register_humongous_region_with_cset(rindex);
3548 // Is_candidate already filters out humongous object with large remembered sets.
3549 // If we have a humongous object with a few remembered sets, we simply flush these
3550 // remembered set entries into the DCQS. That will result in automatic
3551 // re-evaluation of their remembered set entries during the following evacuation
3552 // phase.
3553 if (!r->rem_set()->is_empty()) {
3554 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3555 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3556 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3557 HeapRegionRemSetIterator hrrs(r->rem_set());
3558 size_t card_index;
3559 while (hrrs.has_next(card_index)) {
3560 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3561 // The remembered set might contain references to already freed
3562 // regions. Filter out such entries to avoid failing card table
3563 // verification.
3564 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3565 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3566 *card_ptr = CardTableModRefBS::dirty_card_val();
3567 _dcq.enqueue(card_ptr);
3568 }
3569 }
3570 }
3571 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3572 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3573 hrrs.n_yielded(), r->rem_set()->occupied());
3574 r->rem_set()->clear_locked();
3575 }
3576 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3577 }
3578 _total_humongous++;
3579
3580 return false;
3581 }
3582
3583 size_t total_humongous() const { return _total_humongous; }
3584 size_t candidate_humongous() const { return _candidate_humongous; }
3585
3586 void flush_rem_set_entries() { _dcq.flush(); }
3587 };
3588
3589 void G1CollectedHeap::register_humongous_regions_with_cset() {
3590 if (!G1EagerReclaimHumongousObjects) {
3591 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3592 return;
3593 }
3594 double time = os::elapsed_counter();
3595
3596 // Collect reclaim candidate information and register candidates with cset.
3597 RegisterHumongousWithInCSetFastTestClosure cl;
3598 heap_region_iterate(&cl);
3599
3600 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3601 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3602 cl.total_humongous(),
3603 cl.candidate_humongous());
3604 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3605
3606 // Finally flush all remembered set entries to re-check into the global DCQS.
3607 cl.flush_rem_set_entries();
3608 }
3609
3610 #ifdef ASSERT
3611 class VerifyCSetClosure: public HeapRegionClosure {
3612 public:
3613 bool doHeapRegion(HeapRegion* hr) {
3614 // Here we check that the CSet region's RSet is ready for parallel
3615 // iteration. The fields that we'll verify are only manipulated
3616 // when the region is part of a CSet and is collected. Afterwards,
3617 // we reset these fields when we clear the region's RSet (when the
3618 // region is freed) so they are ready when the region is
3619 // re-allocated. The only exception to this is if there's an
3620 // evacuation failure and instead of freeing the region we leave
3621 // it in the heap. In that case, we reset these fields during
3622 // evacuation failure handling.
3623 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3624
3625 // Here's a good place to add any other checks we'd like to
3626 // perform on CSet regions.
3627 return false;
3628 }
3629 };
3630 #endif // ASSERT
3631
3632 uint G1CollectedHeap::num_task_queues() const {
3633 return _task_queues->size();
3634 }
3635
3636 #if TASKQUEUE_STATS
3637 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3638 st->print_raw_cr("GC Task Stats");
3639 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3640 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3641 }
3642
3643 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3644 print_taskqueue_stats_hdr(st);
3645
3646 TaskQueueStats totals;
3647 const uint n = num_task_queues();
3648 for (uint i = 0; i < n; ++i) {
3649 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3650 totals += task_queue(i)->stats;
3651 }
3652 st->print_raw("tot "); totals.print(st); st->cr();
3653
3654 DEBUG_ONLY(totals.verify());
3655 }
3656
3657 void G1CollectedHeap::reset_taskqueue_stats() {
3658 const uint n = num_task_queues();
3659 for (uint i = 0; i < n; ++i) {
3660 task_queue(i)->stats.reset();
3661 }
3662 }
3663 #endif // TASKQUEUE_STATS
3664
3665 void G1CollectedHeap::log_gc_header() {
3666 if (!G1Log::fine()) {
3667 return;
3668 }
3669
3670 gclog_or_tty->gclog_stamp();
3671
3672 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3673 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3674 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3675
3676 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3677 }
3678
3679 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3680 if (!G1Log::fine()) {
3681 return;
3682 }
3683
3684 if (G1Log::finer()) {
3685 if (evacuation_failed()) {
3686 gclog_or_tty->print(" (to-space exhausted)");
3687 }
3688 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3689 g1_policy()->print_phases(pause_time_sec);
3690 g1_policy()->print_detailed_heap_transition();
3691 } else {
3692 if (evacuation_failed()) {
3693 gclog_or_tty->print("--");
3694 }
3695 g1_policy()->print_heap_transition();
3696 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3697 }
3698 gclog_or_tty->flush();
3699 }
3700
3701 void G1CollectedHeap::wait_for_root_region_scanning() {
3702 double scan_wait_start = os::elapsedTime();
3703 // We have to wait until the CM threads finish scanning the
3704 // root regions as it's the only way to ensure that all the
3705 // objects on them have been correctly scanned before we start
3706 // moving them during the GC.
3707 bool waited = _cm->root_regions()->wait_until_scan_finished();
3708 double wait_time_ms = 0.0;
3709 if (waited) {
3710 double scan_wait_end = os::elapsedTime();
3711 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3712 }
3713 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3714 }
3715
3716 bool
3717 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3718 assert_at_safepoint(true /* should_be_vm_thread */);
3719 guarantee(!is_gc_active(), "collection is not reentrant");
3720
3721 if (GC_locker::check_active_before_gc()) {
3722 return false;
3723 }
3724
3725 _gc_timer_stw->register_gc_start();
3726
3727 GCIdMark gc_id_mark;
3728 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3729
3730 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3731 ResourceMark rm;
3732
3733 wait_for_root_region_scanning();
3734
3735 G1Log::update_level();
3736 print_heap_before_gc();
3737 trace_heap_before_gc(_gc_tracer_stw);
3738
3739 verify_region_sets_optional();
3740 verify_dirty_young_regions();
3741
3742 // This call will decide whether this pause is an initial-mark
3743 // pause. If it is, during_initial_mark_pause() will return true
3744 // for the duration of this pause.
3745 g1_policy()->decide_on_conc_mark_initiation();
3746
3747 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3748 assert(!collector_state()->during_initial_mark_pause() ||
3749 collector_state()->gcs_are_young(), "sanity");
3750
3751 // We also do not allow mixed GCs during marking.
3752 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3753
3754 // Record whether this pause is an initial mark. When the current
3755 // thread has completed its logging output and it's safe to signal
3756 // the CM thread, the flag's value in the policy has been reset.
3757 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3758
3759 // Inner scope for scope based logging, timers, and stats collection
3760 {
3761 EvacuationInfo evacuation_info;
3762
3763 if (collector_state()->during_initial_mark_pause()) {
3764 // We are about to start a marking cycle, so we increment the
3765 // full collection counter.
3766 increment_old_marking_cycles_started();
3767 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3768 }
3769
3770 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3771
3772 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3773
3774 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3775 workers()->active_workers(),
3776 Threads::number_of_non_daemon_threads());
3777 workers()->set_active_workers(active_workers);
3778
3779 double pause_start_sec = os::elapsedTime();
3780 g1_policy()->note_gc_start(active_workers);
3781 log_gc_header();
3782
3783 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3784 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3785
3786 // If the secondary_free_list is not empty, append it to the
3787 // free_list. No need to wait for the cleanup operation to finish;
3788 // the region allocation code will check the secondary_free_list
3789 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3790 // set, skip this step so that the region allocation code has to
3791 // get entries from the secondary_free_list.
3792 if (!G1StressConcRegionFreeing) {
3793 append_secondary_free_list_if_not_empty_with_lock();
3794 }
3795
3796 assert(check_young_list_well_formed(), "young list should be well formed");
3797
3798 // Don't dynamically change the number of GC threads this early. A value of
3799 // 0 is used to indicate serial work. When parallel work is done,
3800 // it will be set.
3801
3802 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3803 IsGCActiveMark x;
3804
3805 gc_prologue(false);
3806 increment_total_collections(false /* full gc */);
3807 increment_gc_time_stamp();
3808
3809 verify_before_gc();
3810
3811 check_bitmaps("GC Start");
3812
3813 #if defined(COMPILER2) || INCLUDE_JVMCI
3814 DerivedPointerTable::clear();
3815 #endif
3816
3817 // Please see comment in g1CollectedHeap.hpp and
3818 // G1CollectedHeap::ref_processing_init() to see how
3819 // reference processing currently works in G1.
3820
3821 // Enable discovery in the STW reference processor
3822 ref_processor_stw()->enable_discovery();
3823
3824 {
3825 // We want to temporarily turn off discovery by the
3826 // CM ref processor, if necessary, and turn it back on
3827 // on again later if we do. Using a scoped
3828 // NoRefDiscovery object will do this.
3829 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3830
3831 // Forget the current alloc region (we might even choose it to be part
3832 // of the collection set!).
3833 _allocator->release_mutator_alloc_region();
3834
3835 // We should call this after we retire the mutator alloc
3836 // region(s) so that all the ALLOC / RETIRE events are generated
3837 // before the start GC event.
3838 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3839
3840 // This timing is only used by the ergonomics to handle our pause target.
3841 // It is unclear why this should not include the full pause. We will
3842 // investigate this in CR 7178365.
3843 //
3844 // Preserving the old comment here if that helps the investigation:
3845 //
3846 // The elapsed time induced by the start time below deliberately elides
3847 // the possible verification above.
3848 double sample_start_time_sec = os::elapsedTime();
3849
3850 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3851
3852 if (collector_state()->during_initial_mark_pause()) {
3853 concurrent_mark()->checkpointRootsInitialPre();
3854 }
3855
3856 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3857 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3858
3859 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3860
3861 // Make sure the remembered sets are up to date. This needs to be
3862 // done before register_humongous_regions_with_cset(), because the
3863 // remembered sets are used there to choose eager reclaim candidates.
3864 // If the remembered sets are not up to date we might miss some
3865 // entries that need to be handled.
3866 g1_rem_set()->cleanupHRRS();
3867
3868 register_humongous_regions_with_cset();
3869
3870 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3871
3872 _cm->note_start_of_gc();
3873 // We call this after finalize_cset() to
3874 // ensure that the CSet has been finalized.
3875 _cm->verify_no_cset_oops();
3876
3877 if (_hr_printer.is_active()) {
3878 HeapRegion* hr = g1_policy()->collection_set();
3879 while (hr != NULL) {
3880 _hr_printer.cset(hr);
3881 hr = hr->next_in_collection_set();
3882 }
3883 }
3884
3885 #ifdef ASSERT
3886 VerifyCSetClosure cl;
3887 collection_set_iterate(&cl);
3888 #endif // ASSERT
3889
3890 // Initialize the GC alloc regions.
3891 _allocator->init_gc_alloc_regions(evacuation_info);
3892
3893 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3894 pre_evacuate_collection_set();
3895
3896 // Actually do the work...
3897 evacuate_collection_set(evacuation_info, &per_thread_states);
3898
3899 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3900
3901 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3902 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3903
3904 eagerly_reclaim_humongous_regions();
3905
3906 g1_policy()->clear_collection_set();
3907
3908 // Start a new incremental collection set for the next pause.
3909 g1_policy()->start_incremental_cset_building();
3910
3911 clear_cset_fast_test();
3912
3913 _young_list->reset_sampled_info();
3914
3915 // Don't check the whole heap at this point as the
3916 // GC alloc regions from this pause have been tagged
3917 // as survivors and moved on to the survivor list.
3918 // Survivor regions will fail the !is_young() check.
3919 assert(check_young_list_empty(false /* check_heap */),
3920 "young list should be empty");
3921
3922 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3923 _young_list->first_survivor_region(),
3924 _young_list->last_survivor_region());
3925
3926 _young_list->reset_auxilary_lists();
3927
3928 if (evacuation_failed()) {
3929 set_used(recalculate_used());
3930 if (_archive_allocator != NULL) {
3931 _archive_allocator->clear_used();
3932 }
3933 for (uint i = 0; i < ParallelGCThreads; i++) {
3934 if (_evacuation_failed_info_array[i].has_failed()) {
3935 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3936 }
3937 }
3938 } else {
3939 // The "used" of the the collection set have already been subtracted
3940 // when they were freed. Add in the bytes evacuated.
3941 increase_used(g1_policy()->bytes_copied_during_gc());
3942 }
3943
3944 if (collector_state()->during_initial_mark_pause()) {
3945 // We have to do this before we notify the CM threads that
3946 // they can start working to make sure that all the
3947 // appropriate initialization is done on the CM object.
3948 concurrent_mark()->checkpointRootsInitialPost();
3949 collector_state()->set_mark_in_progress(true);
3950 // Note that we don't actually trigger the CM thread at
3951 // this point. We do that later when we're sure that
3952 // the current thread has completed its logging output.
3953 }
3954
3955 allocate_dummy_regions();
3956
3957 _allocator->init_mutator_alloc_region();
3958
3959 {
3960 size_t expand_bytes = g1_policy()->expansion_amount();
3961 if (expand_bytes > 0) {
3962 size_t bytes_before = capacity();
3963 // No need for an ergo verbose message here,
3964 // expansion_amount() does this when it returns a value > 0.
3965 double expand_ms;
3966 if (!expand(expand_bytes, &expand_ms)) {
3967 // We failed to expand the heap. Cannot do anything about it.
3968 }
3969 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3970 }
3971 }
3972
3973 // We redo the verification but now wrt to the new CSet which
3974 // has just got initialized after the previous CSet was freed.
3975 _cm->verify_no_cset_oops();
3976 _cm->note_end_of_gc();
3977
3978 // This timing is only used by the ergonomics to handle our pause target.
3979 // It is unclear why this should not include the full pause. We will
3980 // investigate this in CR 7178365.
3981 double sample_end_time_sec = os::elapsedTime();
3982 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3983 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3984 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3985
3986 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3987 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3988
3989 MemoryService::track_memory_usage();
3990
3991 // In prepare_for_verify() below we'll need to scan the deferred
3992 // update buffers to bring the RSets up-to-date if
3993 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3994 // the update buffers we'll probably need to scan cards on the
3995 // regions we just allocated to (i.e., the GC alloc
3996 // regions). However, during the last GC we called
3997 // set_saved_mark() on all the GC alloc regions, so card
3998 // scanning might skip the [saved_mark_word()...top()] area of
3999 // those regions (i.e., the area we allocated objects into
4000 // during the last GC). But it shouldn't. Given that
4001 // saved_mark_word() is conditional on whether the GC time stamp
4002 // on the region is current or not, by incrementing the GC time
4003 // stamp here we invalidate all the GC time stamps on all the
4004 // regions and saved_mark_word() will simply return top() for
4005 // all the regions. This is a nicer way of ensuring this rather
4006 // than iterating over the regions and fixing them. In fact, the
4007 // GC time stamp increment here also ensures that
4008 // saved_mark_word() will return top() between pauses, i.e.,
4009 // during concurrent refinement. So we don't need the
4010 // is_gc_active() check to decided which top to use when
4011 // scanning cards (see CR 7039627).
4012 increment_gc_time_stamp();
4013
4014 verify_after_gc();
4015 check_bitmaps("GC End");
4016
4017 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4018 ref_processor_stw()->verify_no_references_recorded();
4019
4020 // CM reference discovery will be re-enabled if necessary.
4021 }
4022
4023 // We should do this after we potentially expand the heap so
4024 // that all the COMMIT events are generated before the end GC
4025 // event, and after we retire the GC alloc regions so that all
4026 // RETIRE events are generated before the end GC event.
4027 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4028
4029 #ifdef TRACESPINNING
4030 ParallelTaskTerminator::print_termination_counts();
4031 #endif
4032
4033 gc_epilogue(false);
4034 }
4035
4036 // Print the remainder of the GC log output.
4037 log_gc_footer(os::elapsedTime() - pause_start_sec);
4038
4039 // It is not yet to safe to tell the concurrent mark to
4040 // start as we have some optional output below. We don't want the
4041 // output from the concurrent mark thread interfering with this
4042 // logging output either.
4043
4044 _hrm.verify_optional();
4045 verify_region_sets_optional();
4046
4047 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4048 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4049
4050 print_heap_after_gc();
4051 trace_heap_after_gc(_gc_tracer_stw);
4052
4053 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4054 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4055 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4056 // before any GC notifications are raised.
4057 g1mm()->update_sizes();
4058
4059 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4060 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4061 _gc_timer_stw->register_gc_end();
4062 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4063 }
4064 // It should now be safe to tell the concurrent mark thread to start
4065 // without its logging output interfering with the logging output
4066 // that came from the pause.
4067
4068 if (should_start_conc_mark) {
4069 // CAUTION: after the doConcurrentMark() call below,
4070 // the concurrent marking thread(s) could be running
4071 // concurrently with us. Make sure that anything after
4072 // this point does not assume that we are the only GC thread
4073 // running. Note: of course, the actual marking work will
4074 // not start until the safepoint itself is released in
4075 // SuspendibleThreadSet::desynchronize().
4076 doConcurrentMark();
4077 }
4078
4079 return true;
4080 }
4081
4082 void G1CollectedHeap::remove_self_forwarding_pointers() {
4083 double remove_self_forwards_start = os::elapsedTime();
4084
4085 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4086 workers()->run_task(&rsfp_task);
4087
4088 // Now restore saved marks, if any.
4089 for (uint i = 0; i < ParallelGCThreads; i++) {
4090 OopAndMarkOopStack& cur = _preserved_objs[i];
4091 while (!cur.is_empty()) {
4092 OopAndMarkOop elem = cur.pop();
4093 elem.set_mark();
4094 }
4095 cur.clear(true);
4096 }
4097
4098 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4099 }
4100
4101 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4102 if (!_evacuation_failed) {
4103 _evacuation_failed = true;
4104 }
4105
4106 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4107
4108 // We want to call the "for_promotion_failure" version only in the
4109 // case of a promotion failure.
4110 if (m->must_be_preserved_for_promotion_failure(obj)) {
4111 OopAndMarkOop elem(obj, m);
4112 _preserved_objs[worker_id].push(elem);
4113 }
4114 }
4115
4116 class G1ParEvacuateFollowersClosure : public VoidClosure {
4117 private:
4118 double _start_term;
4119 double _term_time;
4120 size_t _term_attempts;
4121
4122 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4123 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4124 protected:
4125 G1CollectedHeap* _g1h;
4126 G1ParScanThreadState* _par_scan_state;
4127 RefToScanQueueSet* _queues;
4128 ParallelTaskTerminator* _terminator;
4129
4130 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4131 RefToScanQueueSet* queues() { return _queues; }
4132 ParallelTaskTerminator* terminator() { return _terminator; }
4133
4134 public:
4135 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4136 G1ParScanThreadState* par_scan_state,
4137 RefToScanQueueSet* queues,
4138 ParallelTaskTerminator* terminator)
4139 : _g1h(g1h), _par_scan_state(par_scan_state),
4140 _queues(queues), _terminator(terminator),
4141 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4142
4143 void do_void();
4144
4145 double term_time() const { return _term_time; }
4146 size_t term_attempts() const { return _term_attempts; }
4147
4148 private:
4149 inline bool offer_termination();
4150 };
4151
4152 bool G1ParEvacuateFollowersClosure::offer_termination() {
4153 G1ParScanThreadState* const pss = par_scan_state();
4154 start_term_time();
4155 const bool res = terminator()->offer_termination();
4156 end_term_time();
4157 return res;
4158 }
4159
4160 void G1ParEvacuateFollowersClosure::do_void() {
4161 G1ParScanThreadState* const pss = par_scan_state();
4162 pss->trim_queue();
4163 do {
4164 pss->steal_and_trim_queue(queues());
4165 } while (!offer_termination());
4166 }
4167
4168 class G1ParTask : public AbstractGangTask {
4169 protected:
4170 G1CollectedHeap* _g1h;
4171 G1ParScanThreadStateSet* _pss;
4172 RefToScanQueueSet* _queues;
4173 G1RootProcessor* _root_processor;
4174 ParallelTaskTerminator _terminator;
4175 uint _n_workers;
4176
4177 public:
4178 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4179 : AbstractGangTask("G1 collection"),
4180 _g1h(g1h),
4181 _pss(per_thread_states),
4182 _queues(task_queues),
4183 _root_processor(root_processor),
4184 _terminator(n_workers, _queues),
4185 _n_workers(n_workers)
4186 {}
4187
4188 void work(uint worker_id) {
4189 if (worker_id >= _n_workers) return; // no work needed this round
4190
4191 double start_sec = os::elapsedTime();
4192 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4193
4194 {
4195 ResourceMark rm;
4196 HandleMark hm;
4197
4198 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4199
4200 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4201 pss->set_ref_processor(rp);
4202
4203 double start_strong_roots_sec = os::elapsedTime();
4204
4205 _root_processor->evacuate_roots(pss->closures(), worker_id);
4206
4207 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4208
4209 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4210 // treating the nmethods visited to act as roots for concurrent marking.
4211 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4212 // objects copied by the current evacuation.
4213 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4214 pss->closures()->weak_codeblobs(),
4215 worker_id);
4216
4217 _pss->add_cards_scanned(worker_id, cards_scanned);
4218
4219 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4220
4221 double term_sec = 0.0;
4222 size_t evac_term_attempts = 0;
4223 {
4224 double start = os::elapsedTime();
4225 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4226 evac.do_void();
4227
4228 evac_term_attempts = evac.term_attempts();
4229 term_sec = evac.term_time();
4230 double elapsed_sec = os::elapsedTime() - start;
4231 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4232 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4233 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4234 }
4235
4236 assert(pss->queue_is_empty(), "should be empty");
4237
4238 if (PrintTerminationStats) {
4239 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4240 size_t lab_waste;
4241 size_t lab_undo_waste;
4242 pss->waste(lab_waste, lab_undo_waste);
4243 _g1h->print_termination_stats(gclog_or_tty,
4244 worker_id,
4245 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4246 strong_roots_sec * 1000.0, /* strong roots time */
4247 term_sec * 1000.0, /* evac term time */
4248 evac_term_attempts, /* evac term attempts */
4249 lab_waste, /* alloc buffer waste */
4250 lab_undo_waste /* undo waste */
4251 );
4252 }
4253
4254 // Close the inner scope so that the ResourceMark and HandleMark
4255 // destructors are executed here and are included as part of the
4256 // "GC Worker Time".
4257 }
4258 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4259 }
4260 };
4261
4262 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4263 st->print_raw_cr("GC Termination Stats");
4264 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4265 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4266 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4267 }
4268
4269 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4270 uint worker_id,
4271 double elapsed_ms,
4272 double strong_roots_ms,
4273 double term_ms,
4274 size_t term_attempts,
4275 size_t alloc_buffer_waste,
4276 size_t undo_waste) const {
4277 st->print_cr("%3d %9.2f %9.2f %6.2f "
4278 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4279 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4280 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4281 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4282 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4283 alloc_buffer_waste * HeapWordSize / K,
4284 undo_waste * HeapWordSize / K);
4285 }
4286
4287 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4288 private:
4289 BoolObjectClosure* _is_alive;
4290 int _initial_string_table_size;
4291 int _initial_symbol_table_size;
4292
4293 bool _process_strings;
4294 int _strings_processed;
4295 int _strings_removed;
4296
4297 bool _process_symbols;
4298 int _symbols_processed;
4299 int _symbols_removed;
4300
4301 public:
4302 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4303 AbstractGangTask("String/Symbol Unlinking"),
4304 _is_alive(is_alive),
4305 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4306 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4307
4308 _initial_string_table_size = StringTable::the_table()->table_size();
4309 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4310 if (process_strings) {
4311 StringTable::clear_parallel_claimed_index();
4312 }
4313 if (process_symbols) {
4314 SymbolTable::clear_parallel_claimed_index();
4315 }
4316 }
4317
4318 ~G1StringSymbolTableUnlinkTask() {
4319 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4320 "claim value %d after unlink less than initial string table size %d",
4321 StringTable::parallel_claimed_index(), _initial_string_table_size);
4322 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4323 "claim value %d after unlink less than initial symbol table size %d",
4324 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4325
4326 if (G1TraceStringSymbolTableScrubbing) {
4327 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4328 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4329 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4330 strings_processed(), strings_removed(),
4331 symbols_processed(), symbols_removed());
4332 }
4333 }
4334
4335 void work(uint worker_id) {
4336 int strings_processed = 0;
4337 int strings_removed = 0;
4338 int symbols_processed = 0;
4339 int symbols_removed = 0;
4340 if (_process_strings) {
4341 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4342 Atomic::add(strings_processed, &_strings_processed);
4343 Atomic::add(strings_removed, &_strings_removed);
4344 }
4345 if (_process_symbols) {
4346 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4347 Atomic::add(symbols_processed, &_symbols_processed);
4348 Atomic::add(symbols_removed, &_symbols_removed);
4349 }
4350 }
4351
4352 size_t strings_processed() const { return (size_t)_strings_processed; }
4353 size_t strings_removed() const { return (size_t)_strings_removed; }
4354
4355 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4356 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4357 };
4358
4359 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4360 private:
4361 static Monitor* _lock;
4362
4363 BoolObjectClosure* const _is_alive;
4364 const bool _unloading_occurred;
4365 const uint _num_workers;
4366
4367 // Variables used to claim nmethods.
4368 nmethod* _first_nmethod;
4369 volatile nmethod* _claimed_nmethod;
4370
4371 // The list of nmethods that need to be processed by the second pass.
4372 volatile nmethod* _postponed_list;
4373 volatile uint _num_entered_barrier;
4374
4375 public:
4376 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4377 _is_alive(is_alive),
4378 _unloading_occurred(unloading_occurred),
4379 _num_workers(num_workers),
4380 _first_nmethod(NULL),
4381 _claimed_nmethod(NULL),
4382 _postponed_list(NULL),
4383 _num_entered_barrier(0)
4384 {
4385 nmethod::increase_unloading_clock();
4386 // Get first alive nmethod
4387 NMethodIterator iter = NMethodIterator();
4388 if(iter.next_alive()) {
4389 _first_nmethod = iter.method();
4390 }
4391 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4392 }
4393
4394 ~G1CodeCacheUnloadingTask() {
4395 CodeCache::verify_clean_inline_caches();
4396
4397 CodeCache::set_needs_cache_clean(false);
4398 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4399
4400 CodeCache::verify_icholder_relocations();
4401 }
4402
4403 private:
4404 void add_to_postponed_list(nmethod* nm) {
4405 nmethod* old;
4406 do {
4407 old = (nmethod*)_postponed_list;
4408 nm->set_unloading_next(old);
4409 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4410 }
4411
4412 void clean_nmethod(nmethod* nm) {
4413 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4414
4415 if (postponed) {
4416 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4417 add_to_postponed_list(nm);
4418 }
4419
4420 // Mark that this thread has been cleaned/unloaded.
4421 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4422 nm->set_unloading_clock(nmethod::global_unloading_clock());
4423 }
4424
4425 void clean_nmethod_postponed(nmethod* nm) {
4426 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4427 }
4428
4429 static const int MaxClaimNmethods = 16;
4430
4431 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4432 nmethod* first;
4433 NMethodIterator last;
4434
4435 do {
4436 *num_claimed_nmethods = 0;
4437
4438 first = (nmethod*)_claimed_nmethod;
4439 last = NMethodIterator(first);
4440
4441 if (first != NULL) {
4442
4443 for (int i = 0; i < MaxClaimNmethods; i++) {
4444 if (!last.next_alive()) {
4445 break;
4446 }
4447 claimed_nmethods[i] = last.method();
4448 (*num_claimed_nmethods)++;
4449 }
4450 }
4451
4452 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4453 }
4454
4455 nmethod* claim_postponed_nmethod() {
4456 nmethod* claim;
4457 nmethod* next;
4458
4459 do {
4460 claim = (nmethod*)_postponed_list;
4461 if (claim == NULL) {
4462 return NULL;
4463 }
4464
4465 next = claim->unloading_next();
4466
4467 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4468
4469 return claim;
4470 }
4471
4472 public:
4473 // Mark that we're done with the first pass of nmethod cleaning.
4474 void barrier_mark(uint worker_id) {
4475 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4476 _num_entered_barrier++;
4477 if (_num_entered_barrier == _num_workers) {
4478 ml.notify_all();
4479 }
4480 }
4481
4482 // See if we have to wait for the other workers to
4483 // finish their first-pass nmethod cleaning work.
4484 void barrier_wait(uint worker_id) {
4485 if (_num_entered_barrier < _num_workers) {
4486 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4487 while (_num_entered_barrier < _num_workers) {
4488 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4489 }
4490 }
4491 }
4492
4493 // Cleaning and unloading of nmethods. Some work has to be postponed
4494 // to the second pass, when we know which nmethods survive.
4495 void work_first_pass(uint worker_id) {
4496 // The first nmethods is claimed by the first worker.
4497 if (worker_id == 0 && _first_nmethod != NULL) {
4498 clean_nmethod(_first_nmethod);
4499 _first_nmethod = NULL;
4500 }
4501
4502 int num_claimed_nmethods;
4503 nmethod* claimed_nmethods[MaxClaimNmethods];
4504
4505 while (true) {
4506 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4507
4508 if (num_claimed_nmethods == 0) {
4509 break;
4510 }
4511
4512 for (int i = 0; i < num_claimed_nmethods; i++) {
4513 clean_nmethod(claimed_nmethods[i]);
4514 }
4515 }
4516 }
4517
4518 void work_second_pass(uint worker_id) {
4519 nmethod* nm;
4520 // Take care of postponed nmethods.
4521 while ((nm = claim_postponed_nmethod()) != NULL) {
4522 clean_nmethod_postponed(nm);
4523 }
4524 }
4525 };
4526
4527 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4528
4529 class G1KlassCleaningTask : public StackObj {
4530 BoolObjectClosure* _is_alive;
4531 volatile jint _clean_klass_tree_claimed;
4532 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4533
4534 public:
4535 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4536 _is_alive(is_alive),
4537 _clean_klass_tree_claimed(0),
4538 _klass_iterator() {
4539 }
4540
4541 private:
4542 bool claim_clean_klass_tree_task() {
4543 if (_clean_klass_tree_claimed) {
4544 return false;
4545 }
4546
4547 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4548 }
4549
4550 InstanceKlass* claim_next_klass() {
4551 Klass* klass;
4552 do {
4553 klass =_klass_iterator.next_klass();
4554 } while (klass != NULL && !klass->is_instance_klass());
4555
4556 // this can be null so don't call InstanceKlass::cast
4557 return static_cast<InstanceKlass*>(klass);
4558 }
4559
4560 public:
4561
4562 void clean_klass(InstanceKlass* ik) {
4563 ik->clean_weak_instanceklass_links(_is_alive);
4564 }
4565
4566 void work() {
4567 ResourceMark rm;
4568
4569 // One worker will clean the subklass/sibling klass tree.
4570 if (claim_clean_klass_tree_task()) {
4571 Klass::clean_subklass_tree(_is_alive);
4572 }
4573
4574 // All workers will help cleaning the classes,
4575 InstanceKlass* klass;
4576 while ((klass = claim_next_klass()) != NULL) {
4577 clean_klass(klass);
4578 }
4579 }
4580 };
4581
4582 // To minimize the remark pause times, the tasks below are done in parallel.
4583 class G1ParallelCleaningTask : public AbstractGangTask {
4584 private:
4585 G1StringSymbolTableUnlinkTask _string_symbol_task;
4586 G1CodeCacheUnloadingTask _code_cache_task;
4587 G1KlassCleaningTask _klass_cleaning_task;
4588
4589 public:
4590 // The constructor is run in the VMThread.
4591 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4592 AbstractGangTask("Parallel Cleaning"),
4593 _string_symbol_task(is_alive, process_strings, process_symbols),
4594 _code_cache_task(num_workers, is_alive, unloading_occurred),
4595 _klass_cleaning_task(is_alive) {
4596 }
4597
4598 // The parallel work done by all worker threads.
4599 void work(uint worker_id) {
4600 // Do first pass of code cache cleaning.
4601 _code_cache_task.work_first_pass(worker_id);
4602
4603 // Let the threads mark that the first pass is done.
4604 _code_cache_task.barrier_mark(worker_id);
4605
4606 // Clean the Strings and Symbols.
4607 _string_symbol_task.work(worker_id);
4608
4609 // Wait for all workers to finish the first code cache cleaning pass.
4610 _code_cache_task.barrier_wait(worker_id);
4611
4612 // Do the second code cache cleaning work, which realize on
4613 // the liveness information gathered during the first pass.
4614 _code_cache_task.work_second_pass(worker_id);
4615
4616 // Clean all klasses that were not unloaded.
4617 _klass_cleaning_task.work();
4618 }
4619 };
4620
4621
4622 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4623 bool process_strings,
4624 bool process_symbols,
4625 bool class_unloading_occurred) {
4626 uint n_workers = workers()->active_workers();
4627
4628 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4629 n_workers, class_unloading_occurred);
4630 workers()->run_task(&g1_unlink_task);
4631 }
4632
4633 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4634 bool process_strings, bool process_symbols) {
4635 {
4636 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4637 workers()->run_task(&g1_unlink_task);
4638 }
4639
4640 if (G1StringDedup::is_enabled()) {
4641 G1StringDedup::unlink(is_alive);
4642 }
4643 }
4644
4645 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4646 private:
4647 DirtyCardQueueSet* _queue;
4648 public:
4649 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4650
4651 virtual void work(uint worker_id) {
4652 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4653 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4654
4655 RedirtyLoggedCardTableEntryClosure cl;
4656 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4657
4658 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4659 }
4660 };
4661
4662 void G1CollectedHeap::redirty_logged_cards() {
4663 double redirty_logged_cards_start = os::elapsedTime();
4664
4665 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4666 dirty_card_queue_set().reset_for_par_iteration();
4667 workers()->run_task(&redirty_task);
4668
4669 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4670 dcq.merge_bufferlists(&dirty_card_queue_set());
4671 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4672
4673 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4674 }
4675
4676 // Weak Reference Processing support
4677
4678 // An always "is_alive" closure that is used to preserve referents.
4679 // If the object is non-null then it's alive. Used in the preservation
4680 // of referent objects that are pointed to by reference objects
4681 // discovered by the CM ref processor.
4682 class G1AlwaysAliveClosure: public BoolObjectClosure {
4683 G1CollectedHeap* _g1;
4684 public:
4685 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4686 bool do_object_b(oop p) {
4687 if (p != NULL) {
4688 return true;
4689 }
4690 return false;
4691 }
4692 };
4693
4694 bool G1STWIsAliveClosure::do_object_b(oop p) {
4695 // An object is reachable if it is outside the collection set,
4696 // or is inside and copied.
4697 return !_g1->is_in_cset(p) || p->is_forwarded();
4698 }
4699
4700 // Non Copying Keep Alive closure
4701 class G1KeepAliveClosure: public OopClosure {
4702 G1CollectedHeap* _g1;
4703 public:
4704 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4705 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4706 void do_oop(oop* p) {
4707 oop obj = *p;
4708 assert(obj != NULL, "the caller should have filtered out NULL values");
4709
4710 const InCSetState cset_state = _g1->in_cset_state(obj);
4711 if (!cset_state.is_in_cset_or_humongous()) {
4712 return;
4713 }
4714 if (cset_state.is_in_cset()) {
4715 assert( obj->is_forwarded(), "invariant" );
4716 *p = obj->forwardee();
4717 } else {
4718 assert(!obj->is_forwarded(), "invariant" );
4719 assert(cset_state.is_humongous(),
4720 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4721 _g1->set_humongous_is_live(obj);
4722 }
4723 }
4724 };
4725
4726 // Copying Keep Alive closure - can be called from both
4727 // serial and parallel code as long as different worker
4728 // threads utilize different G1ParScanThreadState instances
4729 // and different queues.
4730
4731 class G1CopyingKeepAliveClosure: public OopClosure {
4732 G1CollectedHeap* _g1h;
4733 OopClosure* _copy_non_heap_obj_cl;
4734 G1ParScanThreadState* _par_scan_state;
4735
4736 public:
4737 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4738 OopClosure* non_heap_obj_cl,
4739 G1ParScanThreadState* pss):
4740 _g1h(g1h),
4741 _copy_non_heap_obj_cl(non_heap_obj_cl),
4742 _par_scan_state(pss)
4743 {}
4744
4745 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4746 virtual void do_oop( oop* p) { do_oop_work(p); }
4747
4748 template <class T> void do_oop_work(T* p) {
4749 oop obj = oopDesc::load_decode_heap_oop(p);
4750
4751 if (_g1h->is_in_cset_or_humongous(obj)) {
4752 // If the referent object has been forwarded (either copied
4753 // to a new location or to itself in the event of an
4754 // evacuation failure) then we need to update the reference
4755 // field and, if both reference and referent are in the G1
4756 // heap, update the RSet for the referent.
4757 //
4758 // If the referent has not been forwarded then we have to keep
4759 // it alive by policy. Therefore we have copy the referent.
4760 //
4761 // If the reference field is in the G1 heap then we can push
4762 // on the PSS queue. When the queue is drained (after each
4763 // phase of reference processing) the object and it's followers
4764 // will be copied, the reference field set to point to the
4765 // new location, and the RSet updated. Otherwise we need to
4766 // use the the non-heap or metadata closures directly to copy
4767 // the referent object and update the pointer, while avoiding
4768 // updating the RSet.
4769
4770 if (_g1h->is_in_g1_reserved(p)) {
4771 _par_scan_state->push_on_queue(p);
4772 } else {
4773 assert(!Metaspace::contains((const void*)p),
4774 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4775 _copy_non_heap_obj_cl->do_oop(p);
4776 }
4777 }
4778 }
4779 };
4780
4781 // Serial drain queue closure. Called as the 'complete_gc'
4782 // closure for each discovered list in some of the
4783 // reference processing phases.
4784
4785 class G1STWDrainQueueClosure: public VoidClosure {
4786 protected:
4787 G1CollectedHeap* _g1h;
4788 G1ParScanThreadState* _par_scan_state;
4789
4790 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4791
4792 public:
4793 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4794 _g1h(g1h),
4795 _par_scan_state(pss)
4796 { }
4797
4798 void do_void() {
4799 G1ParScanThreadState* const pss = par_scan_state();
4800 pss->trim_queue();
4801 }
4802 };
4803
4804 // Parallel Reference Processing closures
4805
4806 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4807 // processing during G1 evacuation pauses.
4808
4809 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4810 private:
4811 G1CollectedHeap* _g1h;
4812 G1ParScanThreadStateSet* _pss;
4813 RefToScanQueueSet* _queues;
4814 WorkGang* _workers;
4815 uint _active_workers;
4816
4817 public:
4818 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4819 G1ParScanThreadStateSet* per_thread_states,
4820 WorkGang* workers,
4821 RefToScanQueueSet *task_queues,
4822 uint n_workers) :
4823 _g1h(g1h),
4824 _pss(per_thread_states),
4825 _queues(task_queues),
4826 _workers(workers),
4827 _active_workers(n_workers)
4828 {
4829 assert(n_workers > 0, "shouldn't call this otherwise");
4830 }
4831
4832 // Executes the given task using concurrent marking worker threads.
4833 virtual void execute(ProcessTask& task);
4834 virtual void execute(EnqueueTask& task);
4835 };
4836
4837 // Gang task for possibly parallel reference processing
4838
4839 class G1STWRefProcTaskProxy: public AbstractGangTask {
4840 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4841 ProcessTask& _proc_task;
4842 G1CollectedHeap* _g1h;
4843 G1ParScanThreadStateSet* _pss;
4844 RefToScanQueueSet* _task_queues;
4845 ParallelTaskTerminator* _terminator;
4846
4847 public:
4848 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4849 G1CollectedHeap* g1h,
4850 G1ParScanThreadStateSet* per_thread_states,
4851 RefToScanQueueSet *task_queues,
4852 ParallelTaskTerminator* terminator) :
4853 AbstractGangTask("Process reference objects in parallel"),
4854 _proc_task(proc_task),
4855 _g1h(g1h),
4856 _pss(per_thread_states),
4857 _task_queues(task_queues),
4858 _terminator(terminator)
4859 {}
4860
4861 virtual void work(uint worker_id) {
4862 // The reference processing task executed by a single worker.
4863 ResourceMark rm;
4864 HandleMark hm;
4865
4866 G1STWIsAliveClosure is_alive(_g1h);
4867
4868 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4869 pss->set_ref_processor(NULL);
4870
4871 // Keep alive closure.
4872 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4873
4874 // Complete GC closure
4875 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4876
4877 // Call the reference processing task's work routine.
4878 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4879
4880 // Note we cannot assert that the refs array is empty here as not all
4881 // of the processing tasks (specifically phase2 - pp2_work) execute
4882 // the complete_gc closure (which ordinarily would drain the queue) so
4883 // the queue may not be empty.
4884 }
4885 };
4886
4887 // Driver routine for parallel reference processing.
4888 // Creates an instance of the ref processing gang
4889 // task and has the worker threads execute it.
4890 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4891 assert(_workers != NULL, "Need parallel worker threads.");
4892
4893 ParallelTaskTerminator terminator(_active_workers, _queues);
4894 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4895
4896 _workers->run_task(&proc_task_proxy);
4897 }
4898
4899 // Gang task for parallel reference enqueueing.
4900
4901 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4902 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4903 EnqueueTask& _enq_task;
4904
4905 public:
4906 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4907 AbstractGangTask("Enqueue reference objects in parallel"),
4908 _enq_task(enq_task)
4909 { }
4910
4911 virtual void work(uint worker_id) {
4912 _enq_task.work(worker_id);
4913 }
4914 };
4915
4916 // Driver routine for parallel reference enqueueing.
4917 // Creates an instance of the ref enqueueing gang
4918 // task and has the worker threads execute it.
4919
4920 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4921 assert(_workers != NULL, "Need parallel worker threads.");
4922
4923 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4924
4925 _workers->run_task(&enq_task_proxy);
4926 }
4927
4928 // End of weak reference support closures
4929
4930 // Abstract task used to preserve (i.e. copy) any referent objects
4931 // that are in the collection set and are pointed to by reference
4932 // objects discovered by the CM ref processor.
4933
4934 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4935 protected:
4936 G1CollectedHeap* _g1h;
4937 G1ParScanThreadStateSet* _pss;
4938 RefToScanQueueSet* _queues;
4939 ParallelTaskTerminator _terminator;
4940 uint _n_workers;
4941
4942 public:
4943 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4944 AbstractGangTask("ParPreserveCMReferents"),
4945 _g1h(g1h),
4946 _pss(per_thread_states),
4947 _queues(task_queues),
4948 _terminator(workers, _queues),
4949 _n_workers(workers)
4950 { }
4951
4952 void work(uint worker_id) {
4953 ResourceMark rm;
4954 HandleMark hm;
4955
4956 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4957 pss->set_ref_processor(NULL);
4958 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4959
4960 // Is alive closure
4961 G1AlwaysAliveClosure always_alive(_g1h);
4962
4963 // Copying keep alive closure. Applied to referent objects that need
4964 // to be copied.
4965 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4966
4967 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4968
4969 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4970 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4971
4972 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4973 // So this must be true - but assert just in case someone decides to
4974 // change the worker ids.
4975 assert(worker_id < limit, "sanity");
4976 assert(!rp->discovery_is_atomic(), "check this code");
4977
4978 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4979 for (uint idx = worker_id; idx < limit; idx += stride) {
4980 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4981
4982 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4983 while (iter.has_next()) {
4984 // Since discovery is not atomic for the CM ref processor, we
4985 // can see some null referent objects.
4986 iter.load_ptrs(DEBUG_ONLY(true));
4987 oop ref = iter.obj();
4988
4989 // This will filter nulls.
4990 if (iter.is_referent_alive()) {
4991 iter.make_referent_alive();
4992 }
4993 iter.move_to_next();
4994 }
4995 }
4996
4997 // Drain the queue - which may cause stealing
4998 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4999 drain_queue.do_void();
5000 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5001 assert(pss->queue_is_empty(), "should be");
5002 }
5003 };
5004
5005 // Weak Reference processing during an evacuation pause (part 1).
5006 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5007 double ref_proc_start = os::elapsedTime();
5008
5009 ReferenceProcessor* rp = _ref_processor_stw;
5010 assert(rp->discovery_enabled(), "should have been enabled");
5011
5012 // Any reference objects, in the collection set, that were 'discovered'
5013 // by the CM ref processor should have already been copied (either by
5014 // applying the external root copy closure to the discovered lists, or
5015 // by following an RSet entry).
5016 //
5017 // But some of the referents, that are in the collection set, that these
5018 // reference objects point to may not have been copied: the STW ref
5019 // processor would have seen that the reference object had already
5020 // been 'discovered' and would have skipped discovering the reference,
5021 // but would not have treated the reference object as a regular oop.
5022 // As a result the copy closure would not have been applied to the
5023 // referent object.
5024 //
5025 // We need to explicitly copy these referent objects - the references
5026 // will be processed at the end of remarking.
5027 //
5028 // We also need to do this copying before we process the reference
5029 // objects discovered by the STW ref processor in case one of these
5030 // referents points to another object which is also referenced by an
5031 // object discovered by the STW ref processor.
5032
5033 uint no_of_gc_workers = workers()->active_workers();
5034
5035 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5036 per_thread_states,
5037 no_of_gc_workers,
5038 _task_queues);
5039
5040 workers()->run_task(&keep_cm_referents);
5041
5042 // Closure to test whether a referent is alive.
5043 G1STWIsAliveClosure is_alive(this);
5044
5045 // Even when parallel reference processing is enabled, the processing
5046 // of JNI refs is serial and performed serially by the current thread
5047 // rather than by a worker. The following PSS will be used for processing
5048 // JNI refs.
5049
5050 // Use only a single queue for this PSS.
5051 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5052 pss->set_ref_processor(NULL);
5053 assert(pss->queue_is_empty(), "pre-condition");
5054
5055 // Keep alive closure.
5056 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5057
5058 // Serial Complete GC closure
5059 G1STWDrainQueueClosure drain_queue(this, pss);
5060
5061 // Setup the soft refs policy...
5062 rp->setup_policy(false);
5063
5064 ReferenceProcessorStats stats;
5065 if (!rp->processing_is_mt()) {
5066 // Serial reference processing...
5067 stats = rp->process_discovered_references(&is_alive,
5068 &keep_alive,
5069 &drain_queue,
5070 NULL,
5071 _gc_timer_stw);
5072 } else {
5073 // Parallel reference processing
5074 assert(rp->num_q() == no_of_gc_workers, "sanity");
5075 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5076
5077 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5078 stats = rp->process_discovered_references(&is_alive,
5079 &keep_alive,
5080 &drain_queue,
5081 &par_task_executor,
5082 _gc_timer_stw);
5083 }
5084
5085 _gc_tracer_stw->report_gc_reference_stats(stats);
5086
5087 // We have completed copying any necessary live referent objects.
5088 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5089
5090 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5091 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5092 }
5093
5094 // Weak Reference processing during an evacuation pause (part 2).
5095 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5096 double ref_enq_start = os::elapsedTime();
5097
5098 ReferenceProcessor* rp = _ref_processor_stw;
5099 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5100
5101 // Now enqueue any remaining on the discovered lists on to
5102 // the pending list.
5103 if (!rp->processing_is_mt()) {
5104 // Serial reference processing...
5105 rp->enqueue_discovered_references();
5106 } else {
5107 // Parallel reference enqueueing
5108
5109 uint n_workers = workers()->active_workers();
5110
5111 assert(rp->num_q() == n_workers, "sanity");
5112 assert(n_workers <= rp->max_num_q(), "sanity");
5113
5114 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5115 rp->enqueue_discovered_references(&par_task_executor);
5116 }
5117
5118 rp->verify_no_references_recorded();
5119 assert(!rp->discovery_enabled(), "should have been disabled");
5120
5121 // FIXME
5122 // CM's reference processing also cleans up the string and symbol tables.
5123 // Should we do that here also? We could, but it is a serial operation
5124 // and could significantly increase the pause time.
5125
5126 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5127 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5128 }
5129
5130 void G1CollectedHeap::pre_evacuate_collection_set() {
5131 _expand_heap_after_alloc_failure = true;
5132 _evacuation_failed = false;
5133
5134 // Disable the hot card cache.
5135 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5136 hot_card_cache->reset_hot_cache_claimed_index();
5137 hot_card_cache->set_use_cache(false);
5138
5139 }
5140
5141 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5142 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5143
5144 // Should G1EvacuationFailureALot be in effect for this GC?
5145 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5146
5147 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5148 double start_par_time_sec = os::elapsedTime();
5149 double end_par_time_sec;
5150
5151 {
5152 const uint n_workers = workers()->active_workers();
5153 G1RootProcessor root_processor(this, n_workers);
5154 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5155 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5156 if (collector_state()->during_initial_mark_pause()) {
5157 ClassLoaderDataGraph::clear_claimed_marks();
5158 }
5159
5160 // The individual threads will set their evac-failure closures.
5161 if (PrintTerminationStats) {
5162 print_termination_stats_hdr(gclog_or_tty);
5163 }
5164
5165 workers()->run_task(&g1_par_task);
5166 end_par_time_sec = os::elapsedTime();
5167
5168 // Closing the inner scope will execute the destructor
5169 // for the G1RootProcessor object. We record the current
5170 // elapsed time before closing the scope so that time
5171 // taken for the destructor is NOT included in the
5172 // reported parallel time.
5173 }
5174
5175 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5176
5177 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5178 phase_times->record_par_time(par_time_ms);
5179
5180 double code_root_fixup_time_ms =
5181 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5182 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5183
5184 // Process any discovered reference objects - we have
5185 // to do this _before_ we retire the GC alloc regions
5186 // as we may have to copy some 'reachable' referent
5187 // objects (and their reachable sub-graphs) that were
5188 // not copied during the pause.
5189 process_discovered_references(per_thread_states);
5190
5191 if (G1StringDedup::is_enabled()) {
5192 double fixup_start = os::elapsedTime();
5193
5194 G1STWIsAliveClosure is_alive(this);
5195 G1KeepAliveClosure keep_alive(this);
5196 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5197
5198 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5199 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5200 }
5201
5202 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5203
5204 if (evacuation_failed()) {
5205 remove_self_forwarding_pointers();
5206
5207 // Reset the G1EvacuationFailureALot counters and flags
5208 // Note: the values are reset only when an actual
5209 // evacuation failure occurs.
5210 NOT_PRODUCT(reset_evacuation_should_fail();)
5211 }
5212
5213 // Enqueue any remaining references remaining on the STW
5214 // reference processor's discovered lists. We need to do
5215 // this after the card table is cleaned (and verified) as
5216 // the act of enqueueing entries on to the pending list
5217 // will log these updates (and dirty their associated
5218 // cards). We need these updates logged to update any
5219 // RSets.
5220 enqueue_discovered_references(per_thread_states);
5221 }
5222
5223 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5224 _allocator->release_gc_alloc_regions(evacuation_info);
5225
5226 per_thread_states->flush();
5227
5228 record_obj_copy_mem_stats();
5229
5230 _survivor_evac_stats.adjust_desired_plab_sz();
5231 _old_evac_stats.adjust_desired_plab_sz();
5232
5233 // Reset and re-enable the hot card cache.
5234 // Note the counts for the cards in the regions in the
5235 // collection set are reset when the collection set is freed.
5236 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5237 hot_card_cache->reset_hot_cache();
5238 hot_card_cache->set_use_cache(true);
5239
5240 purge_code_root_memory();
5241
5242 redirty_logged_cards();
5243 #if defined(COMPILER2) || INCLUDE_JVMCI
5244 DerivedPointerTable::update_pointers();
5245 #endif
5246 }
5247
5248 void G1CollectedHeap::record_obj_copy_mem_stats() {
5249 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5250 create_g1_evac_summary(&_old_evac_stats));
5251 }
5252
5253 void G1CollectedHeap::free_region(HeapRegion* hr,
5254 FreeRegionList* free_list,
5255 bool par,
5256 bool locked) {
5257 assert(!hr->is_free(), "the region should not be free");
5258 assert(!hr->is_empty(), "the region should not be empty");
5259 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5260 assert(free_list != NULL, "pre-condition");
5261
5262 if (G1VerifyBitmaps) {
5263 MemRegion mr(hr->bottom(), hr->end());
5264 concurrent_mark()->clearRangePrevBitmap(mr);
5265 }
5266
5267 // Clear the card counts for this region.
5268 // Note: we only need to do this if the region is not young
5269 // (since we don't refine cards in young regions).
5270 if (!hr->is_young()) {
5271 _cg1r->hot_card_cache()->reset_card_counts(hr);
5272 }
5273 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5274 free_list->add_ordered(hr);
5275 }
5276
5277 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5278 FreeRegionList* free_list,
5279 bool par) {
5280 assert(hr->is_humongous(), "this is only for humongous regions");
5281 assert(free_list != NULL, "pre-condition");
5282 hr->clear_humongous();
5283 free_region(hr, free_list, par);
5284 }
5285
5286 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5287 const HeapRegionSetCount& humongous_regions_removed) {
5288 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5289 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5290 _old_set.bulk_remove(old_regions_removed);
5291 _humongous_set.bulk_remove(humongous_regions_removed);
5292 }
5293
5294 }
5295
5296 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5297 assert(list != NULL, "list can't be null");
5298 if (!list->is_empty()) {
5299 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5300 _hrm.insert_list_into_free_list(list);
5301 }
5302 }
5303
5304 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5305 decrease_used(bytes);
5306 }
5307
5308 class G1ParCleanupCTTask : public AbstractGangTask {
5309 G1SATBCardTableModRefBS* _ct_bs;
5310 G1CollectedHeap* _g1h;
5311 HeapRegion* volatile _su_head;
5312 public:
5313 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5314 G1CollectedHeap* g1h) :
5315 AbstractGangTask("G1 Par Cleanup CT Task"),
5316 _ct_bs(ct_bs), _g1h(g1h) { }
5317
5318 void work(uint worker_id) {
5319 HeapRegion* r;
5320 while (r = _g1h->pop_dirty_cards_region()) {
5321 clear_cards(r);
5322 }
5323 }
5324
5325 void clear_cards(HeapRegion* r) {
5326 // Cards of the survivors should have already been dirtied.
5327 if (!r->is_survivor()) {
5328 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5329 }
5330 }
5331 };
5332
5333 #ifndef PRODUCT
5334 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5335 G1CollectedHeap* _g1h;
5336 G1SATBCardTableModRefBS* _ct_bs;
5337 public:
5338 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5339 : _g1h(g1h), _ct_bs(ct_bs) { }
5340 virtual bool doHeapRegion(HeapRegion* r) {
5341 if (r->is_survivor()) {
5342 _g1h->verify_dirty_region(r);
5343 } else {
5344 _g1h->verify_not_dirty_region(r);
5345 }
5346 return false;
5347 }
5348 };
5349
5350 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5351 // All of the region should be clean.
5352 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5353 MemRegion mr(hr->bottom(), hr->end());
5354 ct_bs->verify_not_dirty_region(mr);
5355 }
5356
5357 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5358 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5359 // dirty allocated blocks as they allocate them. The thread that
5360 // retires each region and replaces it with a new one will do a
5361 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5362 // not dirty that area (one less thing to have to do while holding
5363 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5364 // is dirty.
5365 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5366 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5367 if (hr->is_young()) {
5368 ct_bs->verify_g1_young_region(mr);
5369 } else {
5370 ct_bs->verify_dirty_region(mr);
5371 }
5372 }
5373
5374 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5375 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5376 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5377 verify_dirty_region(hr);
5378 }
5379 }
5380
5381 void G1CollectedHeap::verify_dirty_young_regions() {
5382 verify_dirty_young_list(_young_list->first_region());
5383 }
5384
5385 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5386 HeapWord* tams, HeapWord* end) {
5387 guarantee(tams <= end,
5388 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5389 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5390 if (result < end) {
5391 gclog_or_tty->cr();
5392 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5393 bitmap_name, p2i(result));
5394 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5395 bitmap_name, p2i(tams), p2i(end));
5396 return false;
5397 }
5398 return true;
5399 }
5400
5401 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5402 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5403 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5404
5405 HeapWord* bottom = hr->bottom();
5406 HeapWord* ptams = hr->prev_top_at_mark_start();
5407 HeapWord* ntams = hr->next_top_at_mark_start();
5408 HeapWord* end = hr->end();
5409
5410 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5411
5412 bool res_n = true;
5413 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5414 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5415 // if we happen to be in that state.
5416 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5417 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5418 }
5419 if (!res_p || !res_n) {
5420 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5421 HR_FORMAT_PARAMS(hr));
5422 gclog_or_tty->print_cr("#### Caller: %s", caller);
5423 return false;
5424 }
5425 return true;
5426 }
5427
5428 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5429 if (!G1VerifyBitmaps) return;
5430
5431 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5432 }
5433
5434 class G1VerifyBitmapClosure : public HeapRegionClosure {
5435 private:
5436 const char* _caller;
5437 G1CollectedHeap* _g1h;
5438 bool _failures;
5439
5440 public:
5441 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5442 _caller(caller), _g1h(g1h), _failures(false) { }
5443
5444 bool failures() { return _failures; }
5445
5446 virtual bool doHeapRegion(HeapRegion* hr) {
5447 bool result = _g1h->verify_bitmaps(_caller, hr);
5448 if (!result) {
5449 _failures = true;
5450 }
5451 return false;
5452 }
5453 };
5454
5455 void G1CollectedHeap::check_bitmaps(const char* caller) {
5456 if (!G1VerifyBitmaps) return;
5457
5458 G1VerifyBitmapClosure cl(caller, this);
5459 heap_region_iterate(&cl);
5460 guarantee(!cl.failures(), "bitmap verification");
5461 }
5462
5463 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5464 private:
5465 bool _failures;
5466 public:
5467 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5468
5469 virtual bool doHeapRegion(HeapRegion* hr) {
5470 uint i = hr->hrm_index();
5471 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5472 if (hr->is_humongous()) {
5473 if (hr->in_collection_set()) {
5474 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5475 _failures = true;
5476 return true;
5477 }
5478 if (cset_state.is_in_cset()) {
5479 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5480 _failures = true;
5481 return true;
5482 }
5483 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5484 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5485 _failures = true;
5486 return true;
5487 }
5488 } else {
5489 if (cset_state.is_humongous()) {
5490 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5491 _failures = true;
5492 return true;
5493 }
5494 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5495 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5496 hr->in_collection_set(), cset_state.value(), i);
5497 _failures = true;
5498 return true;
5499 }
5500 if (cset_state.is_in_cset()) {
5501 if (hr->is_young() != (cset_state.is_young())) {
5502 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5503 hr->is_young(), cset_state.value(), i);
5504 _failures = true;
5505 return true;
5506 }
5507 if (hr->is_old() != (cset_state.is_old())) {
5508 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5509 hr->is_old(), cset_state.value(), i);
5510 _failures = true;
5511 return true;
5512 }
5513 }
5514 }
5515 return false;
5516 }
5517
5518 bool failures() const { return _failures; }
5519 };
5520
5521 bool G1CollectedHeap::check_cset_fast_test() {
5522 G1CheckCSetFastTableClosure cl;
5523 _hrm.iterate(&cl);
5524 return !cl.failures();
5525 }
5526 #endif // PRODUCT
5527
5528 void G1CollectedHeap::cleanUpCardTable() {
5529 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5530 double start = os::elapsedTime();
5531
5532 {
5533 // Iterate over the dirty cards region list.
5534 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5535
5536 workers()->run_task(&cleanup_task);
5537 #ifndef PRODUCT
5538 if (G1VerifyCTCleanup || VerifyAfterGC) {
5539 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5540 heap_region_iterate(&cleanup_verifier);
5541 }
5542 #endif
5543 }
5544
5545 double elapsed = os::elapsedTime() - start;
5546 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5547 }
5548
5549 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5550 size_t pre_used = 0;
5551 FreeRegionList local_free_list("Local List for CSet Freeing");
5552
5553 double young_time_ms = 0.0;
5554 double non_young_time_ms = 0.0;
5555
5556 // Since the collection set is a superset of the the young list,
5557 // all we need to do to clear the young list is clear its
5558 // head and length, and unlink any young regions in the code below
5559 _young_list->clear();
5560
5561 G1CollectorPolicy* policy = g1_policy();
5562
5563 double start_sec = os::elapsedTime();
5564 bool non_young = true;
5565
5566 HeapRegion* cur = cs_head;
5567 int age_bound = -1;
5568 size_t rs_lengths = 0;
5569
5570 while (cur != NULL) {
5571 assert(!is_on_master_free_list(cur), "sanity");
5572 if (non_young) {
5573 if (cur->is_young()) {
5574 double end_sec = os::elapsedTime();
5575 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5576 non_young_time_ms += elapsed_ms;
5577
5578 start_sec = os::elapsedTime();
5579 non_young = false;
5580 }
5581 } else {
5582 if (!cur->is_young()) {
5583 double end_sec = os::elapsedTime();
5584 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5585 young_time_ms += elapsed_ms;
5586
5587 start_sec = os::elapsedTime();
5588 non_young = true;
5589 }
5590 }
5591
5592 rs_lengths += cur->rem_set()->occupied_locked();
5593
5594 HeapRegion* next = cur->next_in_collection_set();
5595 assert(cur->in_collection_set(), "bad CS");
5596 cur->set_next_in_collection_set(NULL);
5597 clear_in_cset(cur);
5598
5599 if (cur->is_young()) {
5600 int index = cur->young_index_in_cset();
5601 assert(index != -1, "invariant");
5602 assert((uint) index < policy->young_cset_region_length(), "invariant");
5603 size_t words_survived = surviving_young_words[index];
5604 cur->record_surv_words_in_group(words_survived);
5605
5606 // At this point the we have 'popped' cur from the collection set
5607 // (linked via next_in_collection_set()) but it is still in the
5608 // young list (linked via next_young_region()). Clear the
5609 // _next_young_region field.
5610 cur->set_next_young_region(NULL);
5611 } else {
5612 int index = cur->young_index_in_cset();
5613 assert(index == -1, "invariant");
5614 }
5615
5616 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5617 (!cur->is_young() && cur->young_index_in_cset() == -1),
5618 "invariant" );
5619
5620 if (!cur->evacuation_failed()) {
5621 MemRegion used_mr = cur->used_region();
5622
5623 // And the region is empty.
5624 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5625 pre_used += cur->used();
5626 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5627 } else {
5628 cur->uninstall_surv_rate_group();
5629 if (cur->is_young()) {
5630 cur->set_young_index_in_cset(-1);
5631 }
5632 cur->set_evacuation_failed(false);
5633 // The region is now considered to be old.
5634 cur->set_old();
5635 // Do some allocation statistics accounting. Regions that failed evacuation
5636 // are always made old, so there is no need to update anything in the young
5637 // gen statistics, but we need to update old gen statistics.
5638 size_t used_words = cur->marked_bytes() / HeapWordSize;
5639 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5640 _old_set.add(cur);
5641 evacuation_info.increment_collectionset_used_after(cur->used());
5642 }
5643 cur = next;
5644 }
5645
5646 evacuation_info.set_regions_freed(local_free_list.length());
5647 policy->record_max_rs_lengths(rs_lengths);
5648 policy->cset_regions_freed();
5649
5650 double end_sec = os::elapsedTime();
5651 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5652
5653 if (non_young) {
5654 non_young_time_ms += elapsed_ms;
5655 } else {
5656 young_time_ms += elapsed_ms;
5657 }
5658
5659 prepend_to_freelist(&local_free_list);
5660 decrement_summary_bytes(pre_used);
5661 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5662 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5663 }
5664
5665 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5666 private:
5667 FreeRegionList* _free_region_list;
5668 HeapRegionSet* _proxy_set;
5669 HeapRegionSetCount _humongous_regions_removed;
5670 size_t _freed_bytes;
5671 public:
5672
5673 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5674 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5675 }
5676
5677 virtual bool doHeapRegion(HeapRegion* r) {
5678 if (!r->is_starts_humongous()) {
5679 return false;
5680 }
5681
5682 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5683
5684 oop obj = (oop)r->bottom();
5685 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5686
5687 // The following checks whether the humongous object is live are sufficient.
5688 // The main additional check (in addition to having a reference from the roots
5689 // or the young gen) is whether the humongous object has a remembered set entry.
5690 //
5691 // A humongous object cannot be live if there is no remembered set for it
5692 // because:
5693 // - there can be no references from within humongous starts regions referencing
5694 // the object because we never allocate other objects into them.
5695 // (I.e. there are no intra-region references that may be missed by the
5696 // remembered set)
5697 // - as soon there is a remembered set entry to the humongous starts region
5698 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5699 // until the end of a concurrent mark.
5700 //
5701 // It is not required to check whether the object has been found dead by marking
5702 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5703 // all objects allocated during that time are considered live.
5704 // SATB marking is even more conservative than the remembered set.
5705 // So if at this point in the collection there is no remembered set entry,
5706 // nobody has a reference to it.
5707 // At the start of collection we flush all refinement logs, and remembered sets
5708 // are completely up-to-date wrt to references to the humongous object.
5709 //
5710 // Other implementation considerations:
5711 // - never consider object arrays at this time because they would pose
5712 // considerable effort for cleaning up the the remembered sets. This is
5713 // required because stale remembered sets might reference locations that
5714 // are currently allocated into.
5715 uint region_idx = r->hrm_index();
5716 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5717 !r->rem_set()->is_empty()) {
5718
5719 if (G1TraceEagerReclaimHumongousObjects) {
5720 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",
5721 region_idx,
5722 (size_t)obj->size() * HeapWordSize,
5723 p2i(r->bottom()),
5724 r->rem_set()->occupied(),
5725 r->rem_set()->strong_code_roots_list_length(),
5726 next_bitmap->isMarked(r->bottom()),
5727 g1h->is_humongous_reclaim_candidate(region_idx),
5728 obj->is_typeArray()
5729 );
5730 }
5731
5732 return false;
5733 }
5734
5735 guarantee(obj->is_typeArray(),
5736 "Only eagerly reclaiming type arrays is supported, but the object "
5737 PTR_FORMAT " is not.", p2i(r->bottom()));
5738
5739 if (G1TraceEagerReclaimHumongousObjects) {
5740 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",
5741 region_idx,
5742 (size_t)obj->size() * HeapWordSize,
5743 p2i(r->bottom()),
5744 r->rem_set()->occupied(),
5745 r->rem_set()->strong_code_roots_list_length(),
5746 next_bitmap->isMarked(r->bottom()),
5747 g1h->is_humongous_reclaim_candidate(region_idx),
5748 obj->is_typeArray()
5749 );
5750 }
5751 // Need to clear mark bit of the humongous object if already set.
5752 if (next_bitmap->isMarked(r->bottom())) {
5753 next_bitmap->clear(r->bottom());
5754 }
5755 do {
5756 HeapRegion* next = g1h->next_region_in_humongous(r);
5757 _freed_bytes += r->used();
5758 r->set_containing_set(NULL);
5759 _humongous_regions_removed.increment(1u, r->capacity());
5760 g1h->free_humongous_region(r, _free_region_list, false);
5761 r = next;
5762 } while (r != NULL);
5763
5764 return false;
5765 }
5766
5767 HeapRegionSetCount& humongous_free_count() {
5768 return _humongous_regions_removed;
5769 }
5770
5771 size_t bytes_freed() const {
5772 return _freed_bytes;
5773 }
5774
5775 size_t humongous_reclaimed() const {
5776 return _humongous_regions_removed.length();
5777 }
5778 };
5779
5780 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5781 assert_at_safepoint(true);
5782
5783 if (!G1EagerReclaimHumongousObjects ||
5784 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5785 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5786 return;
5787 }
5788
5789 double start_time = os::elapsedTime();
5790
5791 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5792
5793 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5794 heap_region_iterate(&cl);
5795
5796 HeapRegionSetCount empty_set;
5797 remove_from_old_sets(empty_set, cl.humongous_free_count());
5798
5799 G1HRPrinter* hrp = hr_printer();
5800 if (hrp->is_active()) {
5801 FreeRegionListIterator iter(&local_cleanup_list);
5802 while (iter.more_available()) {
5803 HeapRegion* hr = iter.get_next();
5804 hrp->cleanup(hr);
5805 }
5806 }
5807
5808 prepend_to_freelist(&local_cleanup_list);
5809 decrement_summary_bytes(cl.bytes_freed());
5810
5811 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5812 cl.humongous_reclaimed());
5813 }
5814
5815 // This routine is similar to the above but does not record
5816 // any policy statistics or update free lists; we are abandoning
5817 // the current incremental collection set in preparation of a
5818 // full collection. After the full GC we will start to build up
5819 // the incremental collection set again.
5820 // This is only called when we're doing a full collection
5821 // and is immediately followed by the tearing down of the young list.
5822
5823 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5824 HeapRegion* cur = cs_head;
5825
5826 while (cur != NULL) {
5827 HeapRegion* next = cur->next_in_collection_set();
5828 assert(cur->in_collection_set(), "bad CS");
5829 cur->set_next_in_collection_set(NULL);
5830 clear_in_cset(cur);
5831 cur->set_young_index_in_cset(-1);
5832 cur = next;
5833 }
5834 }
5835
5836 void G1CollectedHeap::set_free_regions_coming() {
5837 if (G1ConcRegionFreeingVerbose) {
5838 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5839 "setting free regions coming");
5840 }
5841
5842 assert(!free_regions_coming(), "pre-condition");
5843 _free_regions_coming = true;
5844 }
5845
5846 void G1CollectedHeap::reset_free_regions_coming() {
5847 assert(free_regions_coming(), "pre-condition");
5848
5849 {
5850 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5851 _free_regions_coming = false;
5852 SecondaryFreeList_lock->notify_all();
5853 }
5854
5855 if (G1ConcRegionFreeingVerbose) {
5856 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5857 "reset free regions coming");
5858 }
5859 }
5860
5861 void G1CollectedHeap::wait_while_free_regions_coming() {
5862 // Most of the time we won't have to wait, so let's do a quick test
5863 // first before we take the lock.
5864 if (!free_regions_coming()) {
5865 return;
5866 }
5867
5868 if (G1ConcRegionFreeingVerbose) {
5869 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5870 "waiting for free regions");
5871 }
5872
5873 {
5874 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5875 while (free_regions_coming()) {
5876 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5877 }
5878 }
5879
5880 if (G1ConcRegionFreeingVerbose) {
5881 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5882 "done waiting for free regions");
5883 }
5884 }
5885
5886 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5887 return _allocator->is_retained_old_region(hr);
5888 }
5889
5890 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5891 _young_list->push_region(hr);
5892 }
5893
5894 class NoYoungRegionsClosure: public HeapRegionClosure {
5895 private:
5896 bool _success;
5897 public:
5898 NoYoungRegionsClosure() : _success(true) { }
5899 bool doHeapRegion(HeapRegion* r) {
5900 if (r->is_young()) {
5901 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5902 p2i(r->bottom()), p2i(r->end()));
5903 _success = false;
5904 }
5905 return false;
5906 }
5907 bool success() { return _success; }
5908 };
5909
5910 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5911 bool ret = _young_list->check_list_empty(check_sample);
5912
5913 if (check_heap) {
5914 NoYoungRegionsClosure closure;
5915 heap_region_iterate(&closure);
5916 ret = ret && closure.success();
5917 }
5918
5919 return ret;
5920 }
5921
5922 class TearDownRegionSetsClosure : public HeapRegionClosure {
5923 private:
5924 HeapRegionSet *_old_set;
5925
5926 public:
5927 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5928
5929 bool doHeapRegion(HeapRegion* r) {
5930 if (r->is_old()) {
5931 _old_set->remove(r);
5932 } else {
5933 // We ignore free regions, we'll empty the free list afterwards.
5934 // We ignore young regions, we'll empty the young list afterwards.
5935 // We ignore humongous regions, we're not tearing down the
5936 // humongous regions set.
5937 assert(r->is_free() || r->is_young() || r->is_humongous(),
5938 "it cannot be another type");
5939 }
5940 return false;
5941 }
5942
5943 ~TearDownRegionSetsClosure() {
5944 assert(_old_set->is_empty(), "post-condition");
5945 }
5946 };
5947
5948 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5949 assert_at_safepoint(true /* should_be_vm_thread */);
5950
5951 if (!free_list_only) {
5952 TearDownRegionSetsClosure cl(&_old_set);
5953 heap_region_iterate(&cl);
5954
5955 // Note that emptying the _young_list is postponed and instead done as
5956 // the first step when rebuilding the regions sets again. The reason for
5957 // this is that during a full GC string deduplication needs to know if
5958 // a collected region was young or old when the full GC was initiated.
5959 }
5960 _hrm.remove_all_free_regions();
5961 }
5962
5963 void G1CollectedHeap::increase_used(size_t bytes) {
5964 _summary_bytes_used += bytes;
5965 }
5966
5967 void G1CollectedHeap::decrease_used(size_t bytes) {
5968 assert(_summary_bytes_used >= bytes,
5969 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5970 _summary_bytes_used, bytes);
5971 _summary_bytes_used -= bytes;
5972 }
5973
5974 void G1CollectedHeap::set_used(size_t bytes) {
5975 _summary_bytes_used = bytes;
5976 }
5977
5978 class RebuildRegionSetsClosure : public HeapRegionClosure {
5979 private:
5980 bool _free_list_only;
5981 HeapRegionSet* _old_set;
5982 HeapRegionManager* _hrm;
5983 size_t _total_used;
5984
5985 public:
5986 RebuildRegionSetsClosure(bool free_list_only,
5987 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5988 _free_list_only(free_list_only),
5989 _old_set(old_set), _hrm(hrm), _total_used(0) {
5990 assert(_hrm->num_free_regions() == 0, "pre-condition");
5991 if (!free_list_only) {
5992 assert(_old_set->is_empty(), "pre-condition");
5993 }
5994 }
5995
5996 bool doHeapRegion(HeapRegion* r) {
5997 if (r->is_empty()) {
5998 // Add free regions to the free list
5999 r->set_free();
6000 r->set_allocation_context(AllocationContext::system());
6001 _hrm->insert_into_free_list(r);
6002 } else if (!_free_list_only) {
6003 assert(!r->is_young(), "we should not come across young regions");
6004
6005 if (r->is_humongous()) {
6006 // We ignore humongous regions. We left the humongous set unchanged.
6007 } else {
6008 // Objects that were compacted would have ended up on regions
6009 // that were previously old or free. Archive regions (which are
6010 // old) will not have been touched.
6011 assert(r->is_free() || r->is_old(), "invariant");
6012 // We now consider them old, so register as such. Leave
6013 // archive regions set that way, however, while still adding
6014 // them to the old set.
6015 if (!r->is_archive()) {
6016 r->set_old();
6017 }
6018 _old_set->add(r);
6019 }
6020 _total_used += r->used();
6021 }
6022
6023 return false;
6024 }
6025
6026 size_t total_used() {
6027 return _total_used;
6028 }
6029 };
6030
6031 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6032 assert_at_safepoint(true /* should_be_vm_thread */);
6033
6034 if (!free_list_only) {
6035 _young_list->empty_list();
6036 }
6037
6038 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6039 heap_region_iterate(&cl);
6040
6041 if (!free_list_only) {
6042 set_used(cl.total_used());
6043 if (_archive_allocator != NULL) {
6044 _archive_allocator->clear_used();
6045 }
6046 }
6047 assert(used_unlocked() == recalculate_used(),
6048 "inconsistent used_unlocked(), "
6049 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6050 used_unlocked(), recalculate_used());
6051 }
6052
6053 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6054 _refine_cte_cl->set_concurrent(concurrent);
6055 }
6056
6057 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6058 HeapRegion* hr = heap_region_containing(p);
6059 return hr->is_in(p);
6060 }
6061
6062 // Methods for the mutator alloc region
6063
6064 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6065 bool force) {
6066 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6067 assert(!force || g1_policy()->can_expand_young_list(),
6068 "if force is true we should be able to expand the young list");
6069 bool young_list_full = g1_policy()->is_young_list_full();
6070 if (force || !young_list_full) {
6071 HeapRegion* new_alloc_region = new_region(word_size,
6072 false /* is_old */,
6073 false /* do_expand */);
6074 if (new_alloc_region != NULL) {
6075 set_region_short_lived_locked(new_alloc_region);
6076 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6077 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6078 return new_alloc_region;
6079 }
6080 }
6081 return NULL;
6082 }
6083
6084 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6085 size_t allocated_bytes) {
6086 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6087 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6088
6089 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6090 increase_used(allocated_bytes);
6091 _hr_printer.retire(alloc_region);
6092 // We update the eden sizes here, when the region is retired,
6093 // instead of when it's allocated, since this is the point that its
6094 // used space has been recored in _summary_bytes_used.
6095 g1mm()->update_eden_size();
6096 }
6097
6098 // Methods for the GC alloc regions
6099
6100 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6101 uint count,
6102 InCSetState dest) {
6103 assert(FreeList_lock->owned_by_self(), "pre-condition");
6104
6105 if (count < g1_policy()->max_regions(dest)) {
6106 const bool is_survivor = (dest.is_young());
6107 HeapRegion* new_alloc_region = new_region(word_size,
6108 !is_survivor,
6109 true /* do_expand */);
6110 if (new_alloc_region != NULL) {
6111 // We really only need to do this for old regions given that we
6112 // should never scan survivors. But it doesn't hurt to do it
6113 // for survivors too.
6114 new_alloc_region->record_timestamp();
6115 if (is_survivor) {
6116 new_alloc_region->set_survivor();
6117 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6118 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6119 } else {
6120 new_alloc_region->set_old();
6121 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6122 check_bitmaps("Old Region Allocation", new_alloc_region);
6123 }
6124 bool during_im = collector_state()->during_initial_mark_pause();
6125 new_alloc_region->note_start_of_copying(during_im);
6126 return new_alloc_region;
6127 }
6128 }
6129 return NULL;
6130 }
6131
6132 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6133 size_t allocated_bytes,
6134 InCSetState dest) {
6135 bool during_im = collector_state()->during_initial_mark_pause();
6136 alloc_region->note_end_of_copying(during_im);
6137 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6138 if (dest.is_young()) {
6139 young_list()->add_survivor_region(alloc_region);
6140 } else {
6141 _old_set.add(alloc_region);
6142 }
6143 _hr_printer.retire(alloc_region);
6144 }
6145
6146 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6147 bool expanded = false;
6148 uint index = _hrm.find_highest_free(&expanded);
6149
6150 if (index != G1_NO_HRM_INDEX) {
6151 if (expanded) {
6152 ergo_verbose1(ErgoHeapSizing,
6153 "attempt heap expansion",
6154 ergo_format_reason("requested address range outside heap bounds")
6155 ergo_format_byte("region size"),
6156 HeapRegion::GrainWords * HeapWordSize);
6157 }
6158 _hrm.allocate_free_regions_starting_at(index, 1);
6159 return region_at(index);
6160 }
6161 return NULL;
6162 }
6163
6164 // Heap region set verification
6165
6166 class VerifyRegionListsClosure : public HeapRegionClosure {
6167 private:
6168 HeapRegionSet* _old_set;
6169 HeapRegionSet* _humongous_set;
6170 HeapRegionManager* _hrm;
6171
6172 public:
6173 HeapRegionSetCount _old_count;
6174 HeapRegionSetCount _humongous_count;
6175 HeapRegionSetCount _free_count;
6176
6177 VerifyRegionListsClosure(HeapRegionSet* old_set,
6178 HeapRegionSet* humongous_set,
6179 HeapRegionManager* hrm) :
6180 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6181 _old_count(), _humongous_count(), _free_count(){ }
6182
6183 bool doHeapRegion(HeapRegion* hr) {
6184 if (hr->is_young()) {
6185 // TODO
6186 } else if (hr->is_humongous()) {
6187 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6188 _humongous_count.increment(1u, hr->capacity());
6189 } else if (hr->is_empty()) {
6190 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6191 _free_count.increment(1u, hr->capacity());
6192 } else if (hr->is_old()) {
6193 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6194 _old_count.increment(1u, hr->capacity());
6195 } else {
6196 // There are no other valid region types. Check for one invalid
6197 // one we can identify: pinned without old or humongous set.
6198 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6199 ShouldNotReachHere();
6200 }
6201 return false;
6202 }
6203
6204 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6205 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6206 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6207 old_set->total_capacity_bytes(), _old_count.capacity());
6208
6209 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6210 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6211 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6212
6213 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());
6214 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6215 free_list->total_capacity_bytes(), _free_count.capacity());
6216 }
6217 };
6218
6219 void G1CollectedHeap::verify_region_sets() {
6220 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6221
6222 // First, check the explicit lists.
6223 _hrm.verify();
6224 {
6225 // Given that a concurrent operation might be adding regions to
6226 // the secondary free list we have to take the lock before
6227 // verifying it.
6228 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6229 _secondary_free_list.verify_list();
6230 }
6231
6232 // If a concurrent region freeing operation is in progress it will
6233 // be difficult to correctly attributed any free regions we come
6234 // across to the correct free list given that they might belong to
6235 // one of several (free_list, secondary_free_list, any local lists,
6236 // etc.). So, if that's the case we will skip the rest of the
6237 // verification operation. Alternatively, waiting for the concurrent
6238 // operation to complete will have a non-trivial effect on the GC's
6239 // operation (no concurrent operation will last longer than the
6240 // interval between two calls to verification) and it might hide
6241 // any issues that we would like to catch during testing.
6242 if (free_regions_coming()) {
6243 return;
6244 }
6245
6246 // Make sure we append the secondary_free_list on the free_list so
6247 // that all free regions we will come across can be safely
6248 // attributed to the free_list.
6249 append_secondary_free_list_if_not_empty_with_lock();
6250
6251 // Finally, make sure that the region accounting in the lists is
6252 // consistent with what we see in the heap.
6253
6254 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6255 heap_region_iterate(&cl);
6256 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6257 }
6258
6259 // Optimized nmethod scanning
6260
6261 class RegisterNMethodOopClosure: public OopClosure {
6262 G1CollectedHeap* _g1h;
6263 nmethod* _nm;
6264
6265 template <class T> void do_oop_work(T* p) {
6266 T heap_oop = oopDesc::load_heap_oop(p);
6267 if (!oopDesc::is_null(heap_oop)) {
6268 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6269 HeapRegion* hr = _g1h->heap_region_containing(obj);
6270 assert(!hr->is_continues_humongous(),
6271 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6272 " starting at " HR_FORMAT,
6273 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6274
6275 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6276 hr->add_strong_code_root_locked(_nm);
6277 }
6278 }
6279
6280 public:
6281 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6282 _g1h(g1h), _nm(nm) {}
6283
6284 void do_oop(oop* p) { do_oop_work(p); }
6285 void do_oop(narrowOop* p) { do_oop_work(p); }
6286 };
6287
6288 class UnregisterNMethodOopClosure: public OopClosure {
6289 G1CollectedHeap* _g1h;
6290 nmethod* _nm;
6291
6292 template <class T> void do_oop_work(T* p) {
6293 T heap_oop = oopDesc::load_heap_oop(p);
6294 if (!oopDesc::is_null(heap_oop)) {
6295 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6296 HeapRegion* hr = _g1h->heap_region_containing(obj);
6297 assert(!hr->is_continues_humongous(),
6298 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6299 " starting at " HR_FORMAT,
6300 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6301
6302 hr->remove_strong_code_root(_nm);
6303 }
6304 }
6305
6306 public:
6307 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6308 _g1h(g1h), _nm(nm) {}
6309
6310 void do_oop(oop* p) { do_oop_work(p); }
6311 void do_oop(narrowOop* p) { do_oop_work(p); }
6312 };
6313
6314 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6315 CollectedHeap::register_nmethod(nm);
6316
6317 guarantee(nm != NULL, "sanity");
6318 RegisterNMethodOopClosure reg_cl(this, nm);
6319 nm->oops_do(®_cl);
6320 }
6321
6322 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6323 CollectedHeap::unregister_nmethod(nm);
6324
6325 guarantee(nm != NULL, "sanity");
6326 UnregisterNMethodOopClosure reg_cl(this, nm);
6327 nm->oops_do(®_cl, true);
6328 }
6329
6330 void G1CollectedHeap::purge_code_root_memory() {
6331 double purge_start = os::elapsedTime();
6332 G1CodeRootSet::purge();
6333 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6334 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6335 }
6336
6337 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6338 G1CollectedHeap* _g1h;
6339
6340 public:
6341 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6342 _g1h(g1h) {}
6343
6344 void do_code_blob(CodeBlob* cb) {
6345 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6346 if (nm == NULL) {
6347 return;
6348 }
6349
6350 if (ScavengeRootsInCode) {
6351 _g1h->register_nmethod(nm);
6352 }
6353 }
6354 };
6355
6356 void G1CollectedHeap::rebuild_strong_code_roots() {
6357 RebuildStrongCodeRootClosure blob_cl(this);
6358 CodeCache::blobs_do(&blob_cl);
6359 }