1 /*
2 * Copyright (c) 2001, 2016, 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 "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectorPolicy.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1HeapTransition.hpp"
42 #include "gc/g1/g1HeapVerifier.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.inline.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.inline.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "logging/log.hpp"
68 #include "memory/allocation.hpp"
69 #include "memory/iterator.hpp"
70 #include "oops/oop.inline.hpp"
71 #include "runtime/atomic.inline.hpp"
72 #include "runtime/init.hpp"
73 #include "runtime/orderAccess.inline.hpp"
74 #include "runtime/vmThread.hpp"
75 #include "utilities/globalDefinitions.hpp"
76 #include "utilities/stack.inline.hpp"
77
78 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
79
80 // INVARIANTS/NOTES
81 //
82 // All allocation activity covered by the G1CollectedHeap interface is
83 // serialized by acquiring the HeapLock. This happens in mem_allocate
84 // and allocate_new_tlab, which are the "entry" points to the
85 // allocation code from the rest of the JVM. (Note that this does not
86 // apply to TLAB allocation, which is not part of this interface: it
87 // is done by clients of this interface.)
88
89 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure() : _concurrent(true) { }
95
96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
98 // This path is executed by the concurrent refine or mutator threads,
99 // concurrently, and so we do not care if card_ptr contains references
100 // that point into the collection set.
101 assert(!oops_into_cset, "should be");
102
103 if (_concurrent && SuspendibleThreadSet::should_yield()) {
104 // Caller will actually yield.
105 return false;
106 }
107 // Otherwise, we finished successfully; return true.
108 return true;
109 }
110
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
113
114
115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
116 private:
117 size_t _num_dirtied;
118 G1CollectedHeap* _g1h;
119 G1SATBCardTableLoggingModRefBS* _g1_bs;
120
121 HeapRegion* region_for_card(jbyte* card_ptr) const {
122 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
123 }
124
125 bool will_become_free(HeapRegion* hr) const {
126 // A region will be freed by free_collection_set if the region is in the
127 // collection set and has not had an evacuation failure.
128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
129 }
130
131 public:
132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
133 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
134
135 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
136 HeapRegion* hr = region_for_card(card_ptr);
137
138 // Should only dirty cards in regions that won't be freed.
139 if (!will_become_free(hr)) {
140 *card_ptr = CardTableModRefBS::dirty_card_val();
141 _num_dirtied++;
142 }
143
144 return true;
145 }
146
147 size_t num_dirtied() const { return _num_dirtied; }
148 };
149
150
151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
152 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
153 }
154
155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
156 // The from card cache is not the memory that is actually committed. So we cannot
157 // take advantage of the zero_filled parameter.
158 reset_from_card_cache(start_idx, num_regions);
159 }
160
161 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
162 {
163 // Claim the right to put the region on the dirty cards region list
164 // by installing a self pointer.
165 HeapRegion* next = hr->get_next_dirty_cards_region();
166 if (next == NULL) {
167 HeapRegion* res = (HeapRegion*)
168 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
169 NULL);
170 if (res == NULL) {
171 HeapRegion* head;
172 do {
173 // Put the region to the dirty cards region list.
174 head = _dirty_cards_region_list;
175 next = (HeapRegion*)
176 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
177 if (next == head) {
178 assert(hr->get_next_dirty_cards_region() == hr,
179 "hr->get_next_dirty_cards_region() != hr");
180 if (next == NULL) {
181 // The last region in the list points to itself.
182 hr->set_next_dirty_cards_region(hr);
183 } else {
184 hr->set_next_dirty_cards_region(next);
185 }
186 }
187 } while (next != head);
188 }
189 }
190 }
191
192 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
193 {
194 HeapRegion* head;
195 HeapRegion* hr;
196 do {
197 head = _dirty_cards_region_list;
198 if (head == NULL) {
199 return NULL;
200 }
201 HeapRegion* new_head = head->get_next_dirty_cards_region();
202 if (head == new_head) {
203 // The last region.
204 new_head = NULL;
205 }
206 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
207 head);
208 } while (hr != head);
209 assert(hr != NULL, "invariant");
210 hr->set_next_dirty_cards_region(NULL);
211 return hr;
212 }
213
214 // Returns true if the reference points to an object that
215 // can move in an incremental collection.
216 bool G1CollectedHeap::is_scavengable(const void* p) {
217 HeapRegion* hr = heap_region_containing(p);
218 return !hr->is_pinned();
219 }
220
221 // Private methods.
222
223 HeapRegion*
224 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
225 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
226 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
227 if (!_secondary_free_list.is_empty()) {
228 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
229 "secondary_free_list has %u entries",
230 _secondary_free_list.length());
231 // It looks as if there are free regions available on the
232 // secondary_free_list. Let's move them to the free_list and try
233 // again to allocate from it.
234 append_secondary_free_list();
235
236 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
237 "empty we should have moved at least one entry to the free_list");
238 HeapRegion* res = _hrm.allocate_free_region(is_old);
239 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
240 "allocated " HR_FORMAT " from secondary_free_list",
241 HR_FORMAT_PARAMS(res));
242 return res;
243 }
244
245 // Wait here until we get notified either when (a) there are no
246 // more free regions coming or (b) some regions have been moved on
247 // the secondary_free_list.
248 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
249 }
250
251 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
252 "could not allocate from secondary_free_list");
253 return NULL;
254 }
255
256 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
257 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
258 "the only time we use this to allocate a humongous region is "
259 "when we are allocating a single humongous region");
260
261 HeapRegion* res;
262 if (G1StressConcRegionFreeing) {
263 if (!_secondary_free_list.is_empty()) {
264 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
265 "forced to look at the secondary_free_list");
266 res = new_region_try_secondary_free_list(is_old);
267 if (res != NULL) {
268 return res;
269 }
270 }
271 }
272
273 res = _hrm.allocate_free_region(is_old);
274
275 if (res == NULL) {
276 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
277 "res == NULL, trying the secondary_free_list");
278 res = new_region_try_secondary_free_list(is_old);
279 }
280 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
281 // Currently, only attempts to allocate GC alloc regions set
282 // do_expand to true. So, we should only reach here during a
283 // safepoint. If this assumption changes we might have to
284 // reconsider the use of _expand_heap_after_alloc_failure.
285 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
286
287 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
288 word_size * HeapWordSize);
289
290 if (expand(word_size * HeapWordSize)) {
291 // Given that expand() succeeded in expanding the heap, and we
292 // always expand the heap by an amount aligned to the heap
293 // region size, the free list should in theory not be empty.
294 // In either case allocate_free_region() will check for NULL.
295 res = _hrm.allocate_free_region(is_old);
296 } else {
297 _expand_heap_after_alloc_failure = false;
298 }
299 }
300 return res;
301 }
302
303 HeapWord*
304 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
305 uint num_regions,
306 size_t word_size,
307 AllocationContext_t context) {
308 assert(first != G1_NO_HRM_INDEX, "pre-condition");
309 assert(is_humongous(word_size), "word_size should be humongous");
310 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
311
312 // Index of last region in the series.
313 uint last = first + num_regions - 1;
314
315 // We need to initialize the region(s) we just discovered. This is
316 // a bit tricky given that it can happen concurrently with
317 // refinement threads refining cards on these regions and
318 // potentially wanting to refine the BOT as they are scanning
319 // those cards (this can happen shortly after a cleanup; see CR
320 // 6991377). So we have to set up the region(s) carefully and in
321 // a specific order.
322
323 // The word size sum of all the regions we will allocate.
324 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
325 assert(word_size <= word_size_sum, "sanity");
326
327 // This will be the "starts humongous" region.
328 HeapRegion* first_hr = region_at(first);
329 // The header of the new object will be placed at the bottom of
330 // the first region.
331 HeapWord* new_obj = first_hr->bottom();
332 // This will be the new top of the new object.
333 HeapWord* obj_top = new_obj + word_size;
334
335 // First, we need to zero the header of the space that we will be
336 // allocating. When we update top further down, some refinement
337 // threads might try to scan the region. By zeroing the header we
338 // ensure that any thread that will try to scan the region will
339 // come across the zero klass word and bail out.
340 //
341 // NOTE: It would not have been correct to have used
342 // CollectedHeap::fill_with_object() and make the space look like
343 // an int array. The thread that is doing the allocation will
344 // later update the object header to a potentially different array
345 // type and, for a very short period of time, the klass and length
346 // fields will be inconsistent. This could cause a refinement
347 // thread to calculate the object size incorrectly.
348 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
349
350 // How many words we use for filler objects.
351 size_t word_fill_size = word_size_sum - word_size;
352
353 // How many words memory we "waste" which cannot hold a filler object.
354 size_t words_not_fillable = 0;
355
356 if (word_fill_size >= min_fill_size()) {
357 fill_with_objects(obj_top, word_fill_size);
358 } else if (word_fill_size > 0) {
359 // We have space to fill, but we cannot fit an object there.
360 words_not_fillable = word_fill_size;
361 word_fill_size = 0;
362 }
363
364 // We will set up the first region as "starts humongous". This
365 // will also update the BOT covering all the regions to reflect
366 // that there is a single object that starts at the bottom of the
367 // first region.
368 first_hr->set_starts_humongous(obj_top, word_fill_size);
369 first_hr->set_allocation_context(context);
370 // Then, if there are any, we will set up the "continues
371 // humongous" regions.
372 HeapRegion* hr = NULL;
373 for (uint i = first + 1; i <= last; ++i) {
374 hr = region_at(i);
375 hr->set_continues_humongous(first_hr);
376 hr->set_allocation_context(context);
377 }
378
379 // Up to this point no concurrent thread would have been able to
380 // do any scanning on any region in this series. All the top
381 // fields still point to bottom, so the intersection between
382 // [bottom,top] and [card_start,card_end] will be empty. Before we
383 // update the top fields, we'll do a storestore to make sure that
384 // no thread sees the update to top before the zeroing of the
385 // object header and the BOT initialization.
386 OrderAccess::storestore();
387
388 // Now, we will update the top fields of the "continues humongous"
389 // regions except the last one.
390 for (uint i = first; i < last; ++i) {
391 hr = region_at(i);
392 hr->set_top(hr->end());
393 }
394
395 hr = region_at(last);
396 // If we cannot fit a filler object, we must set top to the end
397 // of the humongous object, otherwise we cannot iterate the heap
398 // and the BOT will not be complete.
399 hr->set_top(hr->end() - words_not_fillable);
400
401 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
402 "obj_top should be in last region");
403
404 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
405
406 assert(words_not_fillable == 0 ||
407 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
408 "Miscalculation in humongous allocation");
409
410 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
411
412 for (uint i = first; i <= last; ++i) {
413 hr = region_at(i);
414 _humongous_set.add(hr);
415 _hr_printer.alloc(hr);
416 }
417
418 return new_obj;
419 }
420
421 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
422 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
423 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
424 }
425
426 // If could fit into free regions w/o expansion, try.
427 // Otherwise, if can expand, do so.
428 // Otherwise, if using ex regions might help, try with ex given back.
429 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
430 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
431
432 _verifier->verify_region_sets_optional();
433
434 uint first = G1_NO_HRM_INDEX;
435 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
436
437 if (obj_regions == 1) {
438 // Only one region to allocate, try to use a fast path by directly allocating
439 // from the free lists. Do not try to expand here, we will potentially do that
440 // later.
441 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
442 if (hr != NULL) {
443 first = hr->hrm_index();
444 }
445 } else {
446 // We can't allocate humongous regions spanning more than one region while
447 // cleanupComplete() is running, since some of the regions we find to be
448 // empty might not yet be added to the free list. It is not straightforward
449 // to know in which list they are on so that we can remove them. We only
450 // need to do this if we need to allocate more than one region to satisfy the
451 // current humongous allocation request. If we are only allocating one region
452 // we use the one-region region allocation code (see above), that already
453 // potentially waits for regions from the secondary free list.
454 wait_while_free_regions_coming();
455 append_secondary_free_list_if_not_empty_with_lock();
456
457 // Policy: Try only empty regions (i.e. already committed first). Maybe we
458 // are lucky enough to find some.
459 first = _hrm.find_contiguous_only_empty(obj_regions);
460 if (first != G1_NO_HRM_INDEX) {
461 _hrm.allocate_free_regions_starting_at(first, obj_regions);
462 }
463 }
464
465 if (first == G1_NO_HRM_INDEX) {
466 // Policy: We could not find enough regions for the humongous object in the
467 // free list. Look through the heap to find a mix of free and uncommitted regions.
468 // If so, try expansion.
469 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
470 if (first != G1_NO_HRM_INDEX) {
471 // We found something. Make sure these regions are committed, i.e. expand
472 // the heap. Alternatively we could do a defragmentation GC.
473 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
474 word_size * HeapWordSize);
475
476
477 _hrm.expand_at(first, obj_regions);
478 g1_policy()->record_new_heap_size(num_regions());
479
480 #ifdef ASSERT
481 for (uint i = first; i < first + obj_regions; ++i) {
482 HeapRegion* hr = region_at(i);
483 assert(hr->is_free(), "sanity");
484 assert(hr->is_empty(), "sanity");
485 assert(is_on_master_free_list(hr), "sanity");
486 }
487 #endif
488 _hrm.allocate_free_regions_starting_at(first, obj_regions);
489 } else {
490 // Policy: Potentially trigger a defragmentation GC.
491 }
492 }
493
494 HeapWord* result = NULL;
495 if (first != G1_NO_HRM_INDEX) {
496 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
497 word_size, context);
498 assert(result != NULL, "it should always return a valid result");
499
500 // A successful humongous object allocation changes the used space
501 // information of the old generation so we need to recalculate the
502 // sizes and update the jstat counters here.
503 g1mm()->update_sizes();
504 }
505
506 _verifier->verify_region_sets_optional();
507
508 return result;
509 }
510
511 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
512 assert_heap_not_locked_and_not_at_safepoint();
513 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
514
515 uint dummy_gc_count_before;
516 uint dummy_gclocker_retry_count = 0;
517 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
518 }
519
520 HeapWord*
521 G1CollectedHeap::mem_allocate(size_t word_size,
522 bool* gc_overhead_limit_was_exceeded) {
523 assert_heap_not_locked_and_not_at_safepoint();
524
525 // Loop until the allocation is satisfied, or unsatisfied after GC.
526 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
527 uint gc_count_before;
528
529 HeapWord* result = NULL;
530 if (!is_humongous(word_size)) {
531 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
532 } else {
533 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
534 }
535 if (result != NULL) {
536 return result;
537 }
538
539 // Create the garbage collection operation...
540 VM_G1CollectForAllocation op(gc_count_before, word_size);
541 op.set_allocation_context(AllocationContext::current());
542
543 // ...and get the VM thread to execute it.
544 VMThread::execute(&op);
545
546 if (op.prologue_succeeded() && op.pause_succeeded()) {
547 // If the operation was successful we'll return the result even
548 // if it is NULL. If the allocation attempt failed immediately
549 // after a Full GC, it's unlikely we'll be able to allocate now.
550 HeapWord* result = op.result();
551 if (result != NULL && !is_humongous(word_size)) {
552 // Allocations that take place on VM operations do not do any
553 // card dirtying and we have to do it here. We only have to do
554 // this for non-humongous allocations, though.
555 dirty_young_block(result, word_size);
556 }
557 return result;
558 } else {
559 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
560 return NULL;
561 }
562 assert(op.result() == NULL,
563 "the result should be NULL if the VM op did not succeed");
564 }
565
566 // Give a warning if we seem to be looping forever.
567 if ((QueuedAllocationWarningCount > 0) &&
568 (try_count % QueuedAllocationWarningCount == 0)) {
569 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
570 }
571 }
572
573 ShouldNotReachHere();
574 return NULL;
575 }
576
577 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
578 AllocationContext_t context,
579 uint* gc_count_before_ret,
580 uint* gclocker_retry_count_ret) {
581 // Make sure you read the note in attempt_allocation_humongous().
582
583 assert_heap_not_locked_and_not_at_safepoint();
584 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
585 "be called for humongous allocation requests");
586
587 // We should only get here after the first-level allocation attempt
588 // (attempt_allocation()) failed to allocate.
589
590 // We will loop until a) we manage to successfully perform the
591 // allocation or b) we successfully schedule a collection which
592 // fails to perform the allocation. b) is the only case when we'll
593 // return NULL.
594 HeapWord* result = NULL;
595 for (int try_count = 1; /* we'll return */; try_count += 1) {
596 bool should_try_gc;
597 uint gc_count_before;
598
599 {
600 MutexLockerEx x(Heap_lock);
601 result = _allocator->attempt_allocation_locked(word_size, context);
602 if (result != NULL) {
603 return result;
604 }
605
606 if (GCLocker::is_active_and_needs_gc()) {
607 if (g1_policy()->can_expand_young_list()) {
608 // No need for an ergo verbose message here,
609 // can_expand_young_list() does this when it returns true.
610 result = _allocator->attempt_allocation_force(word_size, context);
611 if (result != NULL) {
612 return result;
613 }
614 }
615 should_try_gc = false;
616 } else {
617 // The GCLocker may not be active but the GCLocker initiated
618 // GC may not yet have been performed (GCLocker::needs_gc()
619 // returns true). In this case we do not try this GC and
620 // wait until the GCLocker initiated GC is performed, and
621 // then retry the allocation.
622 if (GCLocker::needs_gc()) {
623 should_try_gc = false;
624 } else {
625 // Read the GC count while still holding the Heap_lock.
626 gc_count_before = total_collections();
627 should_try_gc = true;
628 }
629 }
630 }
631
632 if (should_try_gc) {
633 bool succeeded;
634 result = do_collection_pause(word_size, gc_count_before, &succeeded,
635 GCCause::_g1_inc_collection_pause);
636 if (result != NULL) {
637 assert(succeeded, "only way to get back a non-NULL result");
638 return result;
639 }
640
641 if (succeeded) {
642 // If we get here we successfully scheduled a collection which
643 // failed to allocate. No point in trying to allocate
644 // further. We'll just return NULL.
645 MutexLockerEx x(Heap_lock);
646 *gc_count_before_ret = total_collections();
647 return NULL;
648 }
649 } else {
650 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
651 MutexLockerEx x(Heap_lock);
652 *gc_count_before_ret = total_collections();
653 return NULL;
654 }
655 // The GCLocker is either active or the GCLocker initiated
656 // GC has not yet been performed. Stall until it is and
657 // then retry the allocation.
658 GCLocker::stall_until_clear();
659 (*gclocker_retry_count_ret) += 1;
660 }
661
662 // We can reach here if we were unsuccessful in scheduling a
663 // collection (because another thread beat us to it) or if we were
664 // stalled due to the GC locker. In either can we should retry the
665 // allocation attempt in case another thread successfully
666 // performed a collection and reclaimed enough space. We do the
667 // first attempt (without holding the Heap_lock) here and the
668 // follow-on attempt will be at the start of the next loop
669 // iteration (after taking the Heap_lock).
670 result = _allocator->attempt_allocation(word_size, context);
671 if (result != NULL) {
672 return result;
673 }
674
675 // Give a warning if we seem to be looping forever.
676 if ((QueuedAllocationWarningCount > 0) &&
677 (try_count % QueuedAllocationWarningCount == 0)) {
678 warning("G1CollectedHeap::attempt_allocation_slow() "
679 "retries %d times", try_count);
680 }
681 }
682
683 ShouldNotReachHere();
684 return NULL;
685 }
686
687 void G1CollectedHeap::begin_archive_alloc_range() {
688 assert_at_safepoint(true /* should_be_vm_thread */);
689 if (_archive_allocator == NULL) {
690 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
691 }
692 }
693
694 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
695 // Allocations in archive regions cannot be of a size that would be considered
696 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
697 // may be different at archive-restore time.
698 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
699 }
700
701 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
702 assert_at_safepoint(true /* should_be_vm_thread */);
703 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
704 if (is_archive_alloc_too_large(word_size)) {
705 return NULL;
706 }
707 return _archive_allocator->archive_mem_allocate(word_size);
708 }
709
710 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
711 size_t end_alignment_in_bytes) {
712 assert_at_safepoint(true /* should_be_vm_thread */);
713 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
714
715 // Call complete_archive to do the real work, filling in the MemRegion
716 // array with the archive regions.
717 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
718 delete _archive_allocator;
719 _archive_allocator = NULL;
720 }
721
722 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
723 assert(ranges != NULL, "MemRegion array NULL");
724 assert(count != 0, "No MemRegions provided");
725 MemRegion reserved = _hrm.reserved();
726 for (size_t i = 0; i < count; i++) {
727 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
728 return false;
729 }
730 }
731 return true;
732 }
733
734 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
735 assert(!is_init_completed(), "Expect to be called at JVM init time");
736 assert(ranges != NULL, "MemRegion array NULL");
737 assert(count != 0, "No MemRegions provided");
738 MutexLockerEx x(Heap_lock);
739
740 MemRegion reserved = _hrm.reserved();
741 HeapWord* prev_last_addr = NULL;
742 HeapRegion* prev_last_region = NULL;
743
744 // Temporarily disable pretouching of heap pages. This interface is used
745 // when mmap'ing archived heap data in, so pre-touching is wasted.
746 FlagSetting fs(AlwaysPreTouch, false);
747
748 // Enable archive object checking in G1MarkSweep. We have to let it know
749 // about each archive range, so that objects in those ranges aren't marked.
750 G1MarkSweep::enable_archive_object_check();
751
752 // For each specified MemRegion range, allocate the corresponding G1
753 // regions and mark them as archive regions. We expect the ranges in
754 // ascending starting address order, without overlap.
755 for (size_t i = 0; i < count; i++) {
756 MemRegion curr_range = ranges[i];
757 HeapWord* start_address = curr_range.start();
758 size_t word_size = curr_range.word_size();
759 HeapWord* last_address = curr_range.last();
760 size_t commits = 0;
761
762 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
763 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
764 p2i(start_address), p2i(last_address));
765 guarantee(start_address > prev_last_addr,
766 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
767 p2i(start_address), p2i(prev_last_addr));
768 prev_last_addr = last_address;
769
770 // Check for ranges that start in the same G1 region in which the previous
771 // range ended, and adjust the start address so we don't try to allocate
772 // the same region again. If the current range is entirely within that
773 // region, skip it, just adjusting the recorded top.
774 HeapRegion* start_region = _hrm.addr_to_region(start_address);
775 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
776 start_address = start_region->end();
777 if (start_address > last_address) {
778 increase_used(word_size * HeapWordSize);
779 start_region->set_top(last_address + 1);
780 continue;
781 }
782 start_region->set_top(start_address);
783 curr_range = MemRegion(start_address, last_address + 1);
784 start_region = _hrm.addr_to_region(start_address);
785 }
786
787 // Perform the actual region allocation, exiting if it fails.
788 // Then note how much new space we have allocated.
789 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
790 return false;
791 }
792 increase_used(word_size * HeapWordSize);
793 if (commits != 0) {
794 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
795 HeapRegion::GrainWords * HeapWordSize * commits);
796
797 }
798
799 // Mark each G1 region touched by the range as archive, add it to the old set,
800 // and set the allocation context and top.
801 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
802 HeapRegion* last_region = _hrm.addr_to_region(last_address);
803 prev_last_region = last_region;
804
805 while (curr_region != NULL) {
806 assert(curr_region->is_empty() && !curr_region->is_pinned(),
807 "Region already in use (index %u)", curr_region->hrm_index());
808 curr_region->set_allocation_context(AllocationContext::system());
809 curr_region->set_archive();
810 _hr_printer.alloc(curr_region);
811 _old_set.add(curr_region);
812 if (curr_region != last_region) {
813 curr_region->set_top(curr_region->end());
814 curr_region = _hrm.next_region_in_heap(curr_region);
815 } else {
816 curr_region->set_top(last_address + 1);
817 curr_region = NULL;
818 }
819 }
820
821 // Notify mark-sweep of the archive range.
822 G1MarkSweep::set_range_archive(curr_range, true);
823 }
824 return true;
825 }
826
827 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
828 assert(!is_init_completed(), "Expect to be called at JVM init time");
829 assert(ranges != NULL, "MemRegion array NULL");
830 assert(count != 0, "No MemRegions provided");
831 MemRegion reserved = _hrm.reserved();
832 HeapWord *prev_last_addr = NULL;
833 HeapRegion* prev_last_region = NULL;
834
835 // For each MemRegion, create filler objects, if needed, in the G1 regions
836 // that contain the address range. The address range actually within the
837 // MemRegion will not be modified. That is assumed to have been initialized
838 // elsewhere, probably via an mmap of archived heap data.
839 MutexLockerEx x(Heap_lock);
840 for (size_t i = 0; i < count; i++) {
841 HeapWord* start_address = ranges[i].start();
842 HeapWord* last_address = ranges[i].last();
843
844 assert(reserved.contains(start_address) && reserved.contains(last_address),
845 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
846 p2i(start_address), p2i(last_address));
847 assert(start_address > prev_last_addr,
848 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
849 p2i(start_address), p2i(prev_last_addr));
850
851 HeapRegion* start_region = _hrm.addr_to_region(start_address);
852 HeapRegion* last_region = _hrm.addr_to_region(last_address);
853 HeapWord* bottom_address = start_region->bottom();
854
855 // Check for a range beginning in the same region in which the
856 // previous one ended.
857 if (start_region == prev_last_region) {
858 bottom_address = prev_last_addr + 1;
859 }
860
861 // Verify that the regions were all marked as archive regions by
862 // alloc_archive_regions.
863 HeapRegion* curr_region = start_region;
864 while (curr_region != NULL) {
865 guarantee(curr_region->is_archive(),
866 "Expected archive region at index %u", curr_region->hrm_index());
867 if (curr_region != last_region) {
868 curr_region = _hrm.next_region_in_heap(curr_region);
869 } else {
870 curr_region = NULL;
871 }
872 }
873
874 prev_last_addr = last_address;
875 prev_last_region = last_region;
876
877 // Fill the memory below the allocated range with dummy object(s),
878 // if the region bottom does not match the range start, or if the previous
879 // range ended within the same G1 region, and there is a gap.
880 if (start_address != bottom_address) {
881 size_t fill_size = pointer_delta(start_address, bottom_address);
882 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
883 increase_used(fill_size * HeapWordSize);
884 }
885 }
886 }
887
888 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
889 uint* gc_count_before_ret,
890 uint* gclocker_retry_count_ret) {
891 assert_heap_not_locked_and_not_at_safepoint();
892 assert(!is_humongous(word_size), "attempt_allocation() should not "
893 "be called for humongous allocation requests");
894
895 AllocationContext_t context = AllocationContext::current();
896 HeapWord* result = _allocator->attempt_allocation(word_size, context);
897
898 if (result == NULL) {
899 result = attempt_allocation_slow(word_size,
900 context,
901 gc_count_before_ret,
902 gclocker_retry_count_ret);
903 }
904 assert_heap_not_locked();
905 if (result != NULL) {
906 dirty_young_block(result, word_size);
907 }
908 return result;
909 }
910
911 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
912 assert(!is_init_completed(), "Expect to be called at JVM init time");
913 assert(ranges != NULL, "MemRegion array NULL");
914 assert(count != 0, "No MemRegions provided");
915 MemRegion reserved = _hrm.reserved();
916 HeapWord* prev_last_addr = NULL;
917 HeapRegion* prev_last_region = NULL;
918 size_t size_used = 0;
919 size_t uncommitted_regions = 0;
920
921 // For each Memregion, free the G1 regions that constitute it, and
922 // notify mark-sweep that the range is no longer to be considered 'archive.'
923 MutexLockerEx x(Heap_lock);
924 for (size_t i = 0; i < count; i++) {
925 HeapWord* start_address = ranges[i].start();
926 HeapWord* last_address = ranges[i].last();
927
928 assert(reserved.contains(start_address) && reserved.contains(last_address),
929 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
930 p2i(start_address), p2i(last_address));
931 assert(start_address > prev_last_addr,
932 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
933 p2i(start_address), p2i(prev_last_addr));
934 size_used += ranges[i].byte_size();
935 prev_last_addr = last_address;
936
937 HeapRegion* start_region = _hrm.addr_to_region(start_address);
938 HeapRegion* last_region = _hrm.addr_to_region(last_address);
939
940 // Check for ranges that start in the same G1 region in which the previous
941 // range ended, and adjust the start address so we don't try to free
942 // the same region again. If the current range is entirely within that
943 // region, skip it.
944 if (start_region == prev_last_region) {
945 start_address = start_region->end();
946 if (start_address > last_address) {
947 continue;
948 }
949 start_region = _hrm.addr_to_region(start_address);
950 }
951 prev_last_region = last_region;
952
953 // After verifying that each region was marked as an archive region by
954 // alloc_archive_regions, set it free and empty and uncommit it.
955 HeapRegion* curr_region = start_region;
956 while (curr_region != NULL) {
957 guarantee(curr_region->is_archive(),
958 "Expected archive region at index %u", curr_region->hrm_index());
959 uint curr_index = curr_region->hrm_index();
960 _old_set.remove(curr_region);
961 curr_region->set_free();
962 curr_region->set_top(curr_region->bottom());
963 if (curr_region != last_region) {
964 curr_region = _hrm.next_region_in_heap(curr_region);
965 } else {
966 curr_region = NULL;
967 }
968 _hrm.shrink_at(curr_index, 1);
969 uncommitted_regions++;
970 }
971
972 // Notify mark-sweep that this is no longer an archive range.
973 G1MarkSweep::set_range_archive(ranges[i], false);
974 }
975
976 if (uncommitted_regions != 0) {
977 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
978 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
979 }
980 decrease_used(size_used);
981 }
982
983 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
984 uint* gc_count_before_ret,
985 uint* gclocker_retry_count_ret) {
986 // The structure of this method has a lot of similarities to
987 // attempt_allocation_slow(). The reason these two were not merged
988 // into a single one is that such a method would require several "if
989 // allocation is not humongous do this, otherwise do that"
990 // conditional paths which would obscure its flow. In fact, an early
991 // version of this code did use a unified method which was harder to
992 // follow and, as a result, it had subtle bugs that were hard to
993 // track down. So keeping these two methods separate allows each to
994 // be more readable. It will be good to keep these two in sync as
995 // much as possible.
996
997 assert_heap_not_locked_and_not_at_safepoint();
998 assert(is_humongous(word_size), "attempt_allocation_humongous() "
999 "should only be called for humongous allocations");
1000
1001 // Humongous objects can exhaust the heap quickly, so we should check if we
1002 // need to start a marking cycle at each humongous object allocation. We do
1003 // the check before we do the actual allocation. The reason for doing it
1004 // before the allocation is that we avoid having to keep track of the newly
1005 // allocated memory while we do a GC.
1006 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1007 word_size)) {
1008 collect(GCCause::_g1_humongous_allocation);
1009 }
1010
1011 // We will loop until a) we manage to successfully perform the
1012 // allocation or b) we successfully schedule a collection which
1013 // fails to perform the allocation. b) is the only case when we'll
1014 // return NULL.
1015 HeapWord* result = NULL;
1016 for (int try_count = 1; /* we'll return */; try_count += 1) {
1017 bool should_try_gc;
1018 uint gc_count_before;
1019
1020 {
1021 MutexLockerEx x(Heap_lock);
1022
1023 // Given that humongous objects are not allocated in young
1024 // regions, we'll first try to do the allocation without doing a
1025 // collection hoping that there's enough space in the heap.
1026 result = humongous_obj_allocate(word_size, AllocationContext::current());
1027 if (result != NULL) {
1028 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1029 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1030 return result;
1031 }
1032
1033 if (GCLocker::is_active_and_needs_gc()) {
1034 should_try_gc = false;
1035 } else {
1036 // The GCLocker may not be active but the GCLocker initiated
1037 // GC may not yet have been performed (GCLocker::needs_gc()
1038 // returns true). In this case we do not try this GC and
1039 // wait until the GCLocker initiated GC is performed, and
1040 // then retry the allocation.
1041 if (GCLocker::needs_gc()) {
1042 should_try_gc = false;
1043 } else {
1044 // Read the GC count while still holding the Heap_lock.
1045 gc_count_before = total_collections();
1046 should_try_gc = true;
1047 }
1048 }
1049 }
1050
1051 if (should_try_gc) {
1052 // If we failed to allocate the humongous object, we should try to
1053 // do a collection pause (if we're allowed) in case it reclaims
1054 // enough space for the allocation to succeed after the pause.
1055
1056 bool succeeded;
1057 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1058 GCCause::_g1_humongous_allocation);
1059 if (result != NULL) {
1060 assert(succeeded, "only way to get back a non-NULL result");
1061 return result;
1062 }
1063
1064 if (succeeded) {
1065 // If we get here we successfully scheduled a collection which
1066 // failed to allocate. No point in trying to allocate
1067 // further. We'll just return NULL.
1068 MutexLockerEx x(Heap_lock);
1069 *gc_count_before_ret = total_collections();
1070 return NULL;
1071 }
1072 } else {
1073 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1074 MutexLockerEx x(Heap_lock);
1075 *gc_count_before_ret = total_collections();
1076 return NULL;
1077 }
1078 // The GCLocker is either active or the GCLocker initiated
1079 // GC has not yet been performed. Stall until it is and
1080 // then retry the allocation.
1081 GCLocker::stall_until_clear();
1082 (*gclocker_retry_count_ret) += 1;
1083 }
1084
1085 // We can reach here if we were unsuccessful in scheduling a
1086 // collection (because another thread beat us to it) or if we were
1087 // stalled due to the GC locker. In either can we should retry the
1088 // allocation attempt in case another thread successfully
1089 // performed a collection and reclaimed enough space. Give a
1090 // warning if we seem to be looping forever.
1091
1092 if ((QueuedAllocationWarningCount > 0) &&
1093 (try_count % QueuedAllocationWarningCount == 0)) {
1094 warning("G1CollectedHeap::attempt_allocation_humongous() "
1095 "retries %d times", try_count);
1096 }
1097 }
1098
1099 ShouldNotReachHere();
1100 return NULL;
1101 }
1102
1103 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1104 AllocationContext_t context,
1105 bool expect_null_mutator_alloc_region) {
1106 assert_at_safepoint(true /* should_be_vm_thread */);
1107 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1108 "the current alloc region was unexpectedly found to be non-NULL");
1109
1110 if (!is_humongous(word_size)) {
1111 return _allocator->attempt_allocation_locked(word_size, context);
1112 } else {
1113 HeapWord* result = humongous_obj_allocate(word_size, context);
1114 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1115 collector_state()->set_initiate_conc_mark_if_possible(true);
1116 }
1117 return result;
1118 }
1119
1120 ShouldNotReachHere();
1121 }
1122
1123 class PostMCRemSetClearClosure: public HeapRegionClosure {
1124 G1CollectedHeap* _g1h;
1125 ModRefBarrierSet* _mr_bs;
1126 public:
1127 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1128 _g1h(g1h), _mr_bs(mr_bs) {}
1129
1130 bool doHeapRegion(HeapRegion* r) {
1131 HeapRegionRemSet* hrrs = r->rem_set();
1132
1133 _g1h->reset_gc_time_stamps(r);
1134
1135 if (r->is_continues_humongous()) {
1136 // We'll assert that the strong code root list and RSet is empty
1137 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1138 assert(hrrs->occupied() == 0, "RSet should be empty");
1139 } else {
1140 hrrs->clear();
1141 }
1142 // You might think here that we could clear just the cards
1143 // corresponding to the used region. But no: if we leave a dirty card
1144 // in a region we might allocate into, then it would prevent that card
1145 // from being enqueued, and cause it to be missed.
1146 // Re: the performance cost: we shouldn't be doing full GC anyway!
1147 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1148
1149 return false;
1150 }
1151 };
1152
1153 void G1CollectedHeap::clear_rsets_post_compaction() {
1154 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1155 heap_region_iterate(&rs_clear);
1156 }
1157
1158 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1159 G1CollectedHeap* _g1h;
1160 UpdateRSOopClosure _cl;
1161 public:
1162 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1163 _cl(g1->g1_rem_set(), worker_i),
1164 _g1h(g1)
1165 { }
1166
1167 bool doHeapRegion(HeapRegion* r) {
1168 if (!r->is_continues_humongous()) {
1169 _cl.set_from(r);
1170 r->oop_iterate(&_cl);
1171 }
1172 return false;
1173 }
1174 };
1175
1176 class ParRebuildRSTask: public AbstractGangTask {
1177 G1CollectedHeap* _g1;
1178 HeapRegionClaimer _hrclaimer;
1179
1180 public:
1181 ParRebuildRSTask(G1CollectedHeap* g1) :
1182 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1183
1184 void work(uint worker_id) {
1185 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1186 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1187 }
1188 };
1189
1190 class PostCompactionPrinterClosure: public HeapRegionClosure {
1191 private:
1192 G1HRPrinter* _hr_printer;
1193 public:
1194 bool doHeapRegion(HeapRegion* hr) {
1195 assert(!hr->is_young(), "not expecting to find young regions");
1196 _hr_printer->post_compaction(hr);
1197 return false;
1198 }
1199
1200 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1201 : _hr_printer(hr_printer) { }
1202 };
1203
1204 void G1CollectedHeap::print_hrm_post_compaction() {
1205 if (_hr_printer.is_active()) {
1206 PostCompactionPrinterClosure cl(hr_printer());
1207 heap_region_iterate(&cl);
1208 }
1209
1210 }
1211
1212 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1213 bool clear_all_soft_refs) {
1214 assert_at_safepoint(true /* should_be_vm_thread */);
1215
1216 if (GCLocker::check_active_before_gc()) {
1217 return false;
1218 }
1219
1220 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1221 gc_timer->register_gc_start();
1222
1223 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1224 GCIdMark gc_id_mark;
1225 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1226
1227 SvcGCMarker sgcm(SvcGCMarker::FULL);
1228 ResourceMark rm;
1229
1230 print_heap_before_gc();
1231 trace_heap_before_gc(gc_tracer);
1232
1233 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1234
1235 _verifier->verify_region_sets_optional();
1236
1237 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1238 collector_policy()->should_clear_all_soft_refs();
1239
1240 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1241
1242 {
1243 IsGCActiveMark x;
1244
1245 // Timing
1246 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1247 GCTraceCPUTime tcpu;
1248
1249 {
1250 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1251 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1252 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1253
1254 G1HeapTransition heap_transition(this);
1255 g1_policy()->record_full_collection_start();
1256
1257 // Note: When we have a more flexible GC logging framework that
1258 // allows us to add optional attributes to a GC log record we
1259 // could consider timing and reporting how long we wait in the
1260 // following two methods.
1261 wait_while_free_regions_coming();
1262 // If we start the compaction before the CM threads finish
1263 // scanning the root regions we might trip them over as we'll
1264 // be moving objects / updating references. So let's wait until
1265 // they are done. By telling them to abort, they should complete
1266 // early.
1267 _cm->root_regions()->abort();
1268 _cm->root_regions()->wait_until_scan_finished();
1269 append_secondary_free_list_if_not_empty_with_lock();
1270
1271 gc_prologue(true);
1272 increment_total_collections(true /* full gc */);
1273 increment_old_marking_cycles_started();
1274
1275 assert(used() == recalculate_used(), "Should be equal");
1276
1277 _verifier->verify_before_gc();
1278
1279 _verifier->check_bitmaps("Full GC Start");
1280 pre_full_gc_dump(gc_timer);
1281
1282 #if defined(COMPILER2) || INCLUDE_JVMCI
1283 DerivedPointerTable::clear();
1284 #endif
1285
1286 // Disable discovery and empty the discovered lists
1287 // for the CM ref processor.
1288 ref_processor_cm()->disable_discovery();
1289 ref_processor_cm()->abandon_partial_discovery();
1290 ref_processor_cm()->verify_no_references_recorded();
1291
1292 // Abandon current iterations of concurrent marking and concurrent
1293 // refinement, if any are in progress.
1294 concurrent_mark()->abort();
1295
1296 // Make sure we'll choose a new allocation region afterwards.
1297 _allocator->release_mutator_alloc_region();
1298 _allocator->abandon_gc_alloc_regions();
1299 g1_rem_set()->cleanupHRRS();
1300
1301 // We may have added regions to the current incremental collection
1302 // set between the last GC or pause and now. We need to clear the
1303 // incremental collection set and then start rebuilding it afresh
1304 // after this full GC.
1305 abandon_collection_set(g1_policy()->inc_cset_head());
1306 g1_policy()->clear_incremental_cset();
1307 g1_policy()->stop_incremental_cset_building();
1308
1309 tear_down_region_sets(false /* free_list_only */);
1310 collector_state()->set_gcs_are_young(true);
1311
1312 // See the comments in g1CollectedHeap.hpp and
1313 // G1CollectedHeap::ref_processing_init() about
1314 // how reference processing currently works in G1.
1315
1316 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1317 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1318
1319 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1320 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1321
1322 ref_processor_stw()->enable_discovery();
1323 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1324
1325 // Do collection work
1326 {
1327 HandleMark hm; // Discard invalid handles created during gc
1328 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1329 }
1330
1331 assert(num_free_regions() == 0, "we should not have added any free regions");
1332 rebuild_region_sets(false /* free_list_only */);
1333
1334 // Enqueue any discovered reference objects that have
1335 // not been removed from the discovered lists.
1336 ref_processor_stw()->enqueue_discovered_references();
1337
1338 #if defined(COMPILER2) || INCLUDE_JVMCI
1339 DerivedPointerTable::update_pointers();
1340 #endif
1341
1342 MemoryService::track_memory_usage();
1343
1344 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1345 ref_processor_stw()->verify_no_references_recorded();
1346
1347 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1348 ClassLoaderDataGraph::purge();
1349 MetaspaceAux::verify_metrics();
1350
1351 // Note: since we've just done a full GC, concurrent
1352 // marking is no longer active. Therefore we need not
1353 // re-enable reference discovery for the CM ref processor.
1354 // That will be done at the start of the next marking cycle.
1355 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1356 ref_processor_cm()->verify_no_references_recorded();
1357
1358 reset_gc_time_stamp();
1359 // Since everything potentially moved, we will clear all remembered
1360 // sets, and clear all cards. Later we will rebuild remembered
1361 // sets. We will also reset the GC time stamps of the regions.
1362 clear_rsets_post_compaction();
1363 check_gc_time_stamps();
1364
1365 resize_if_necessary_after_full_collection();
1366
1367 // We should do this after we potentially resize the heap so
1368 // that all the COMMIT / UNCOMMIT events are generated before
1369 // the compaction events.
1370 print_hrm_post_compaction();
1371
1372 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1373 if (hot_card_cache->use_cache()) {
1374 hot_card_cache->reset_card_counts();
1375 hot_card_cache->reset_hot_cache();
1376 }
1377
1378 // Rebuild remembered sets of all regions.
1379 uint n_workers =
1380 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1381 workers()->active_workers(),
1382 Threads::number_of_non_daemon_threads());
1383 workers()->set_active_workers(n_workers);
1384
1385 ParRebuildRSTask rebuild_rs_task(this);
1386 workers()->run_task(&rebuild_rs_task);
1387
1388 // Rebuild the strong code root lists for each region
1389 rebuild_strong_code_roots();
1390
1391 if (true) { // FIXME
1392 MetaspaceGC::compute_new_size();
1393 }
1394
1395 #ifdef TRACESPINNING
1396 ParallelTaskTerminator::print_termination_counts();
1397 #endif
1398
1399 // Discard all rset updates
1400 JavaThread::dirty_card_queue_set().abandon_logs();
1401 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1402
1403 _young_list->reset_sampled_info();
1404 // At this point there should be no regions in the
1405 // entire heap tagged as young.
1406 assert(check_young_list_empty(true /* check_heap */),
1407 "young list should be empty at this point");
1408
1409 // Update the number of full collections that have been completed.
1410 increment_old_marking_cycles_completed(false /* concurrent */);
1411
1412 _hrm.verify_optional();
1413 _verifier->verify_region_sets_optional();
1414
1415 _verifier->verify_after_gc();
1416
1417 // Clear the previous marking bitmap, if needed for bitmap verification.
1418 // Note we cannot do this when we clear the next marking bitmap in
1419 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1420 // objects marked during a full GC against the previous bitmap.
1421 // But we need to clear it before calling check_bitmaps below since
1422 // the full GC has compacted objects and updated TAMS but not updated
1423 // the prev bitmap.
1424 if (G1VerifyBitmaps) {
1425 ((G1CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1426 }
1427 _verifier->check_bitmaps("Full GC End");
1428
1429 // Start a new incremental collection set for the next pause
1430 assert(g1_policy()->collection_set() == NULL, "must be");
1431 g1_policy()->start_incremental_cset_building();
1432
1433 clear_cset_fast_test();
1434
1435 _allocator->init_mutator_alloc_region();
1436
1437 g1_policy()->record_full_collection_end();
1438
1439 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1440 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1441 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1442 // before any GC notifications are raised.
1443 g1mm()->update_sizes();
1444
1445 gc_epilogue(true);
1446
1447 heap_transition.print();
1448
1449 print_heap_after_gc();
1450 trace_heap_after_gc(gc_tracer);
1451
1452 post_full_gc_dump(gc_timer);
1453 }
1454
1455 gc_timer->register_gc_end();
1456 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1457 }
1458
1459 return true;
1460 }
1461
1462 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1463 // Currently, there is no facility in the do_full_collection(bool) API to notify
1464 // the caller that the collection did not succeed (e.g., because it was locked
1465 // out by the GC locker). So, right now, we'll ignore the return value.
1466 bool dummy = do_full_collection(true, /* explicit_gc */
1467 clear_all_soft_refs);
1468 }
1469
1470 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1471 // Include bytes that will be pre-allocated to support collections, as "used".
1472 const size_t used_after_gc = used();
1473 const size_t capacity_after_gc = capacity();
1474 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1475
1476 // This is enforced in arguments.cpp.
1477 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1478 "otherwise the code below doesn't make sense");
1479
1480 // We don't have floating point command-line arguments
1481 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1482 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1483 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1484 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1485
1486 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1487 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1488
1489 // We have to be careful here as these two calculations can overflow
1490 // 32-bit size_t's.
1491 double used_after_gc_d = (double) used_after_gc;
1492 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1493 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1494
1495 // Let's make sure that they are both under the max heap size, which
1496 // by default will make them fit into a size_t.
1497 double desired_capacity_upper_bound = (double) max_heap_size;
1498 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1499 desired_capacity_upper_bound);
1500 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1501 desired_capacity_upper_bound);
1502
1503 // We can now safely turn them into size_t's.
1504 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1505 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1506
1507 // This assert only makes sense here, before we adjust them
1508 // with respect to the min and max heap size.
1509 assert(minimum_desired_capacity <= maximum_desired_capacity,
1510 "minimum_desired_capacity = " SIZE_FORMAT ", "
1511 "maximum_desired_capacity = " SIZE_FORMAT,
1512 minimum_desired_capacity, maximum_desired_capacity);
1513
1514 // Should not be greater than the heap max size. No need to adjust
1515 // it with respect to the heap min size as it's a lower bound (i.e.,
1516 // we'll try to make the capacity larger than it, not smaller).
1517 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1518 // Should not be less than the heap min size. No need to adjust it
1519 // with respect to the heap max size as it's an upper bound (i.e.,
1520 // we'll try to make the capacity smaller than it, not greater).
1521 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1522
1523 if (capacity_after_gc < minimum_desired_capacity) {
1524 // Don't expand unless it's significant
1525 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1526
1527 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1528 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1529 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1530
1531 expand(expand_bytes);
1532
1533 // No expansion, now see if we want to shrink
1534 } else if (capacity_after_gc > maximum_desired_capacity) {
1535 // Capacity too large, compute shrinking size
1536 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1537
1538 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1539 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1540 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1541
1542 shrink(shrink_bytes);
1543 }
1544 }
1545
1546 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1547 AllocationContext_t context,
1548 bool do_gc,
1549 bool clear_all_soft_refs,
1550 bool expect_null_mutator_alloc_region,
1551 bool* gc_succeeded) {
1552 *gc_succeeded = true;
1553 // Let's attempt the allocation first.
1554 HeapWord* result =
1555 attempt_allocation_at_safepoint(word_size,
1556 context,
1557 expect_null_mutator_alloc_region);
1558 if (result != NULL) {
1559 assert(*gc_succeeded, "sanity");
1560 return result;
1561 }
1562
1563 // In a G1 heap, we're supposed to keep allocation from failing by
1564 // incremental pauses. Therefore, at least for now, we'll favor
1565 // expansion over collection. (This might change in the future if we can
1566 // do something smarter than full collection to satisfy a failed alloc.)
1567 result = expand_and_allocate(word_size, context);
1568 if (result != NULL) {
1569 assert(*gc_succeeded, "sanity");
1570 return result;
1571 }
1572
1573 if (do_gc) {
1574 // Expansion didn't work, we'll try to do a Full GC.
1575 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1576 clear_all_soft_refs);
1577 }
1578
1579 return NULL;
1580 }
1581
1582 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1583 AllocationContext_t context,
1584 bool* succeeded) {
1585 assert_at_safepoint(true /* should_be_vm_thread */);
1586
1587 // Attempts to allocate followed by Full GC.
1588 HeapWord* result =
1589 satisfy_failed_allocation_helper(word_size,
1590 context,
1591 true, /* do_gc */
1592 false, /* clear_all_soft_refs */
1593 false, /* expect_null_mutator_alloc_region */
1594 succeeded);
1595
1596 if (result != NULL || !*succeeded) {
1597 return result;
1598 }
1599
1600 // Attempts to allocate followed by Full GC that will collect all soft references.
1601 result = satisfy_failed_allocation_helper(word_size,
1602 context,
1603 true, /* do_gc */
1604 true, /* clear_all_soft_refs */
1605 true, /* expect_null_mutator_alloc_region */
1606 succeeded);
1607
1608 if (result != NULL || !*succeeded) {
1609 return result;
1610 }
1611
1612 // Attempts to allocate, no GC
1613 result = satisfy_failed_allocation_helper(word_size,
1614 context,
1615 false, /* do_gc */
1616 false, /* clear_all_soft_refs */
1617 true, /* expect_null_mutator_alloc_region */
1618 succeeded);
1619
1620 if (result != NULL) {
1621 assert(*succeeded, "sanity");
1622 return result;
1623 }
1624
1625 assert(!collector_policy()->should_clear_all_soft_refs(),
1626 "Flag should have been handled and cleared prior to this point");
1627
1628 // What else? We might try synchronous finalization later. If the total
1629 // space available is large enough for the allocation, then a more
1630 // complete compaction phase than we've tried so far might be
1631 // appropriate.
1632 assert(*succeeded, "sanity");
1633 return NULL;
1634 }
1635
1636 // Attempting to expand the heap sufficiently
1637 // to support an allocation of the given "word_size". If
1638 // successful, perform the allocation and return the address of the
1639 // allocated block, or else "NULL".
1640
1641 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1642 assert_at_safepoint(true /* should_be_vm_thread */);
1643
1644 _verifier->verify_region_sets_optional();
1645
1646 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1647 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1648 word_size * HeapWordSize);
1649
1650
1651 if (expand(expand_bytes)) {
1652 _hrm.verify_optional();
1653 _verifier->verify_region_sets_optional();
1654 return attempt_allocation_at_safepoint(word_size,
1655 context,
1656 false /* expect_null_mutator_alloc_region */);
1657 }
1658 return NULL;
1659 }
1660
1661 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1662 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1663 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1664 HeapRegion::GrainBytes);
1665
1666 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1667 expand_bytes, aligned_expand_bytes);
1668
1669 if (is_maximal_no_gc()) {
1670 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1671 return false;
1672 }
1673
1674 double expand_heap_start_time_sec = os::elapsedTime();
1675 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1676 assert(regions_to_expand > 0, "Must expand by at least one region");
1677
1678 uint expanded_by = _hrm.expand_by(regions_to_expand);
1679 if (expand_time_ms != NULL) {
1680 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1681 }
1682
1683 if (expanded_by > 0) {
1684 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1685 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1686 g1_policy()->record_new_heap_size(num_regions());
1687 } else {
1688 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1689
1690 // The expansion of the virtual storage space was unsuccessful.
1691 // Let's see if it was because we ran out of swap.
1692 if (G1ExitOnExpansionFailure &&
1693 _hrm.available() >= regions_to_expand) {
1694 // We had head room...
1695 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1696 }
1697 }
1698 return regions_to_expand > 0;
1699 }
1700
1701 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1702 size_t aligned_shrink_bytes =
1703 ReservedSpace::page_align_size_down(shrink_bytes);
1704 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1705 HeapRegion::GrainBytes);
1706 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1707
1708 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1709 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1710
1711
1712 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1713 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1714 if (num_regions_removed > 0) {
1715 g1_policy()->record_new_heap_size(num_regions());
1716 } else {
1717 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1718 }
1719 }
1720
1721 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1722 _verifier->verify_region_sets_optional();
1723
1724 // We should only reach here at the end of a Full GC which means we
1725 // should not not be holding to any GC alloc regions. The method
1726 // below will make sure of that and do any remaining clean up.
1727 _allocator->abandon_gc_alloc_regions();
1728
1729 // Instead of tearing down / rebuilding the free lists here, we
1730 // could instead use the remove_all_pending() method on free_list to
1731 // remove only the ones that we need to remove.
1732 tear_down_region_sets(true /* free_list_only */);
1733 shrink_helper(shrink_bytes);
1734 rebuild_region_sets(true /* free_list_only */);
1735
1736 _hrm.verify_optional();
1737 _verifier->verify_region_sets_optional();
1738 }
1739
1740 // Public methods.
1741
1742 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1743 CollectedHeap(),
1744 _g1_policy(policy_),
1745 _dirty_card_queue_set(false),
1746 _is_alive_closure_cm(this),
1747 _is_alive_closure_stw(this),
1748 _ref_processor_cm(NULL),
1749 _ref_processor_stw(NULL),
1750 _bot(NULL),
1751 _cg1r(NULL),
1752 _g1mm(NULL),
1753 _refine_cte_cl(NULL),
1754 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1755 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1756 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1757 _humongous_reclaim_candidates(),
1758 _has_humongous_reclaim_candidates(false),
1759 _archive_allocator(NULL),
1760 _free_regions_coming(false),
1761 _young_list(new YoungList(this)),
1762 _gc_time_stamp(0),
1763 _summary_bytes_used(0),
1764 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1765 _old_evac_stats(OldPLABSize, PLABWeight),
1766 _expand_heap_after_alloc_failure(true),
1767 _old_marking_cycles_started(0),
1768 _old_marking_cycles_completed(0),
1769 _heap_summary_sent(false),
1770 _in_cset_fast_test(),
1771 _dirty_cards_region_list(NULL),
1772 _worker_cset_start_region(NULL),
1773 _worker_cset_start_region_time_stamp(NULL),
1774 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1775 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1776 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1777 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1778
1779 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1780 /* are_GC_task_threads */true,
1781 /* are_ConcurrentGC_threads */false);
1782 _workers->initialize_workers();
1783 _verifier = new G1HeapVerifier(this);
1784
1785 _allocator = G1Allocator::create_allocator(this);
1786 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1787
1788 // Override the default _filler_array_max_size so that no humongous filler
1789 // objects are created.
1790 _filler_array_max_size = _humongous_object_threshold_in_words;
1791
1792 uint n_queues = ParallelGCThreads;
1793 _task_queues = new RefToScanQueueSet(n_queues);
1794
1795 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1796 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1797 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1798
1799 for (uint i = 0; i < n_queues; i++) {
1800 RefToScanQueue* q = new RefToScanQueue();
1801 q->initialize();
1802 _task_queues->register_queue(i, q);
1803 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1804 }
1805 clear_cset_start_regions();
1806
1807 // Initialize the G1EvacuationFailureALot counters and flags.
1808 NOT_PRODUCT(reset_evacuation_should_fail();)
1809
1810 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1811 }
1812
1813 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1814 size_t size,
1815 size_t translation_factor) {
1816 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1817 // Allocate a new reserved space, preferring to use large pages.
1818 ReservedSpace rs(size, preferred_page_size);
1819 G1RegionToSpaceMapper* result =
1820 G1RegionToSpaceMapper::create_mapper(rs,
1821 size,
1822 rs.alignment(),
1823 HeapRegion::GrainBytes,
1824 translation_factor,
1825 mtGC);
1826 if (TracePageSizes) {
1827 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1828 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1829 }
1830 return result;
1831 }
1832
1833 jint G1CollectedHeap::initialize() {
1834 CollectedHeap::pre_initialize();
1835 os::enable_vtime();
1836
1837 // Necessary to satisfy locking discipline assertions.
1838
1839 MutexLocker x(Heap_lock);
1840
1841 // While there are no constraints in the GC code that HeapWordSize
1842 // be any particular value, there are multiple other areas in the
1843 // system which believe this to be true (e.g. oop->object_size in some
1844 // cases incorrectly returns the size in wordSize units rather than
1845 // HeapWordSize).
1846 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1847
1848 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1849 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1850 size_t heap_alignment = collector_policy()->heap_alignment();
1851
1852 // Ensure that the sizes are properly aligned.
1853 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1854 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1855 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1856
1857 _refine_cte_cl = new RefineCardTableEntryClosure();
1858
1859 jint ecode = JNI_OK;
1860 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1861 if (_cg1r == NULL) {
1862 return ecode;
1863 }
1864
1865 // Reserve the maximum.
1866
1867 // When compressed oops are enabled, the preferred heap base
1868 // is calculated by subtracting the requested size from the
1869 // 32Gb boundary and using the result as the base address for
1870 // heap reservation. If the requested size is not aligned to
1871 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1872 // into the ReservedHeapSpace constructor) then the actual
1873 // base of the reserved heap may end up differing from the
1874 // address that was requested (i.e. the preferred heap base).
1875 // If this happens then we could end up using a non-optimal
1876 // compressed oops mode.
1877
1878 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1879 heap_alignment);
1880
1881 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1882
1883 // Create the barrier set for the entire reserved region.
1884 G1SATBCardTableLoggingModRefBS* bs
1885 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1886 bs->initialize();
1887 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1888 set_barrier_set(bs);
1889
1890 // Also create a G1 rem set.
1891 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1892
1893 // Carve out the G1 part of the heap.
1894 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1895 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1896 G1RegionToSpaceMapper* heap_storage =
1897 G1RegionToSpaceMapper::create_mapper(g1_rs,
1898 g1_rs.size(),
1899 page_size,
1900 HeapRegion::GrainBytes,
1901 1,
1902 mtJavaHeap);
1903 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1904 max_byte_size, page_size,
1905 heap_rs.base(),
1906 heap_rs.size());
1907 heap_storage->set_mapping_changed_listener(&_listener);
1908
1909 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1910 G1RegionToSpaceMapper* bot_storage =
1911 create_aux_memory_mapper("Block offset table",
1912 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1913 G1BlockOffsetTable::heap_map_factor());
1914
1915 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1916 G1RegionToSpaceMapper* cardtable_storage =
1917 create_aux_memory_mapper("Card table",
1918 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1919 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1920
1921 G1RegionToSpaceMapper* card_counts_storage =
1922 create_aux_memory_mapper("Card counts table",
1923 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1924 G1CardCounts::heap_map_factor());
1925
1926 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1927 G1RegionToSpaceMapper* prev_bitmap_storage =
1928 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1929 G1RegionToSpaceMapper* next_bitmap_storage =
1930 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1931
1932 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1933 g1_barrier_set()->initialize(cardtable_storage);
1934 // Do later initialization work for concurrent refinement.
1935 _cg1r->init(card_counts_storage);
1936
1937 // 6843694 - ensure that the maximum region index can fit
1938 // in the remembered set structures.
1939 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1940 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1941
1942 G1RemSet::initialize(max_regions());
1943
1944 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1945 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1946 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1947 "too many cards per region");
1948
1949 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1950
1951 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1952
1953 {
1954 HeapWord* start = _hrm.reserved().start();
1955 HeapWord* end = _hrm.reserved().end();
1956 size_t granularity = HeapRegion::GrainBytes;
1957
1958 _in_cset_fast_test.initialize(start, end, granularity);
1959 _humongous_reclaim_candidates.initialize(start, end, granularity);
1960 }
1961
1962 // Create the G1ConcurrentMark data structure and thread.
1963 // (Must do this late, so that "max_regions" is defined.)
1964 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1965 if (_cm == NULL || !_cm->completed_initialization()) {
1966 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1967 return JNI_ENOMEM;
1968 }
1969 _cmThread = _cm->cmThread();
1970
1971 // Now expand into the initial heap size.
1972 if (!expand(init_byte_size)) {
1973 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1974 return JNI_ENOMEM;
1975 }
1976
1977 // Perform any initialization actions delegated to the policy.
1978 g1_policy()->init();
1979
1980 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1981 SATB_Q_FL_lock,
1982 G1SATBProcessCompletedThreshold,
1983 Shared_SATB_Q_lock);
1984
1985 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1986 DirtyCardQ_CBL_mon,
1987 DirtyCardQ_FL_lock,
1988 concurrent_g1_refine()->yellow_zone(),
1989 concurrent_g1_refine()->red_zone(),
1990 Shared_DirtyCardQ_lock,
1991 NULL, // fl_owner
1992 true); // init_free_ids
1993
1994 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1995 DirtyCardQ_CBL_mon,
1996 DirtyCardQ_FL_lock,
1997 -1, // never trigger processing
1998 -1, // no limit on length
1999 Shared_DirtyCardQ_lock,
2000 &JavaThread::dirty_card_queue_set());
2001
2002 // Here we allocate the dummy HeapRegion that is required by the
2003 // G1AllocRegion class.
2004 HeapRegion* dummy_region = _hrm.get_dummy_region();
2005
2006 // We'll re-use the same region whether the alloc region will
2007 // require BOT updates or not and, if it doesn't, then a non-young
2008 // region will complain that it cannot support allocations without
2009 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2010 dummy_region->set_eden();
2011 // Make sure it's full.
2012 dummy_region->set_top(dummy_region->end());
2013 G1AllocRegion::setup(this, dummy_region);
2014
2015 _allocator->init_mutator_alloc_region();
2016
2017 // Do create of the monitoring and management support so that
2018 // values in the heap have been properly initialized.
2019 _g1mm = new G1MonitoringSupport(this);
2020
2021 G1StringDedup::initialize();
2022
2023 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2024 for (uint i = 0; i < ParallelGCThreads; i++) {
2025 new (&_preserved_objs[i]) OopAndMarkOopStack();
2026 }
2027
2028 return JNI_OK;
2029 }
2030
2031 void G1CollectedHeap::stop() {
2032 // Stop all concurrent threads. We do this to make sure these threads
2033 // do not continue to execute and access resources (e.g. logging)
2034 // that are destroyed during shutdown.
2035 _cg1r->stop();
2036 _cmThread->stop();
2037 if (G1StringDedup::is_enabled()) {
2038 G1StringDedup::stop();
2039 }
2040 }
2041
2042 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2043 return HeapRegion::max_region_size();
2044 }
2045
2046 void G1CollectedHeap::post_initialize() {
2047 CollectedHeap::post_initialize();
2048 ref_processing_init();
2049 }
2050
2051 void G1CollectedHeap::ref_processing_init() {
2052 // Reference processing in G1 currently works as follows:
2053 //
2054 // * There are two reference processor instances. One is
2055 // used to record and process discovered references
2056 // during concurrent marking; the other is used to
2057 // record and process references during STW pauses
2058 // (both full and incremental).
2059 // * Both ref processors need to 'span' the entire heap as
2060 // the regions in the collection set may be dotted around.
2061 //
2062 // * For the concurrent marking ref processor:
2063 // * Reference discovery is enabled at initial marking.
2064 // * Reference discovery is disabled and the discovered
2065 // references processed etc during remarking.
2066 // * Reference discovery is MT (see below).
2067 // * Reference discovery requires a barrier (see below).
2068 // * Reference processing may or may not be MT
2069 // (depending on the value of ParallelRefProcEnabled
2070 // and ParallelGCThreads).
2071 // * A full GC disables reference discovery by the CM
2072 // ref processor and abandons any entries on it's
2073 // discovered lists.
2074 //
2075 // * For the STW processor:
2076 // * Non MT discovery is enabled at the start of a full GC.
2077 // * Processing and enqueueing during a full GC is non-MT.
2078 // * During a full GC, references are processed after marking.
2079 //
2080 // * Discovery (may or may not be MT) is enabled at the start
2081 // of an incremental evacuation pause.
2082 // * References are processed near the end of a STW evacuation pause.
2083 // * For both types of GC:
2084 // * Discovery is atomic - i.e. not concurrent.
2085 // * Reference discovery will not need a barrier.
2086
2087 MemRegion mr = reserved_region();
2088
2089 // Concurrent Mark ref processor
2090 _ref_processor_cm =
2091 new ReferenceProcessor(mr, // span
2092 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2093 // mt processing
2094 ParallelGCThreads,
2095 // degree of mt processing
2096 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2097 // mt discovery
2098 MAX2(ParallelGCThreads, ConcGCThreads),
2099 // degree of mt discovery
2100 false,
2101 // Reference discovery is not atomic
2102 &_is_alive_closure_cm);
2103 // is alive closure
2104 // (for efficiency/performance)
2105
2106 // STW ref processor
2107 _ref_processor_stw =
2108 new ReferenceProcessor(mr, // span
2109 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2110 // mt processing
2111 ParallelGCThreads,
2112 // degree of mt processing
2113 (ParallelGCThreads > 1),
2114 // mt discovery
2115 ParallelGCThreads,
2116 // degree of mt discovery
2117 true,
2118 // Reference discovery is atomic
2119 &_is_alive_closure_stw);
2120 // is alive closure
2121 // (for efficiency/performance)
2122 }
2123
2124 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2125 return g1_policy();
2126 }
2127
2128 size_t G1CollectedHeap::capacity() const {
2129 return _hrm.length() * HeapRegion::GrainBytes;
2130 }
2131
2132 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2133 hr->reset_gc_time_stamp();
2134 }
2135
2136 #ifndef PRODUCT
2137
2138 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2139 private:
2140 unsigned _gc_time_stamp;
2141 bool _failures;
2142
2143 public:
2144 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2145 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2146
2147 virtual bool doHeapRegion(HeapRegion* hr) {
2148 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2149 if (_gc_time_stamp != region_gc_time_stamp) {
2150 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2151 region_gc_time_stamp, _gc_time_stamp);
2152 _failures = true;
2153 }
2154 return false;
2155 }
2156
2157 bool failures() { return _failures; }
2158 };
2159
2160 void G1CollectedHeap::check_gc_time_stamps() {
2161 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2162 heap_region_iterate(&cl);
2163 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2164 }
2165 #endif // PRODUCT
2166
2167 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2168 _cg1r->hot_card_cache()->drain(cl, worker_i);
2169 }
2170
2171 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2172 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2173 size_t n_completed_buffers = 0;
2174 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2175 n_completed_buffers++;
2176 }
2177 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2178 dcqs.clear_n_completed_buffers();
2179 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2180 }
2181
2182 // Computes the sum of the storage used by the various regions.
2183 size_t G1CollectedHeap::used() const {
2184 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2185 if (_archive_allocator != NULL) {
2186 result += _archive_allocator->used();
2187 }
2188 return result;
2189 }
2190
2191 size_t G1CollectedHeap::used_unlocked() const {
2192 return _summary_bytes_used;
2193 }
2194
2195 class SumUsedClosure: public HeapRegionClosure {
2196 size_t _used;
2197 public:
2198 SumUsedClosure() : _used(0) {}
2199 bool doHeapRegion(HeapRegion* r) {
2200 _used += r->used();
2201 return false;
2202 }
2203 size_t result() { return _used; }
2204 };
2205
2206 size_t G1CollectedHeap::recalculate_used() const {
2207 double recalculate_used_start = os::elapsedTime();
2208
2209 SumUsedClosure blk;
2210 heap_region_iterate(&blk);
2211
2212 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2213 return blk.result();
2214 }
2215
2216 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2217 switch (cause) {
2218 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2219 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2220 case GCCause::_update_allocation_context_stats_inc: return true;
2221 case GCCause::_wb_conc_mark: return true;
2222 default : return false;
2223 }
2224 }
2225
2226 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2227 switch (cause) {
2228 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2229 case GCCause::_g1_humongous_allocation: return true;
2230 default: return is_user_requested_concurrent_full_gc(cause);
2231 }
2232 }
2233
2234 #ifndef PRODUCT
2235 void G1CollectedHeap::allocate_dummy_regions() {
2236 // Let's fill up most of the region
2237 size_t word_size = HeapRegion::GrainWords - 1024;
2238 // And as a result the region we'll allocate will be humongous.
2239 guarantee(is_humongous(word_size), "sanity");
2240
2241 // _filler_array_max_size is set to humongous object threshold
2242 // but temporarily change it to use CollectedHeap::fill_with_object().
2243 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2244
2245 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2246 // Let's use the existing mechanism for the allocation
2247 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2248 AllocationContext::system());
2249 if (dummy_obj != NULL) {
2250 MemRegion mr(dummy_obj, word_size);
2251 CollectedHeap::fill_with_object(mr);
2252 } else {
2253 // If we can't allocate once, we probably cannot allocate
2254 // again. Let's get out of the loop.
2255 break;
2256 }
2257 }
2258 }
2259 #endif // !PRODUCT
2260
2261 void G1CollectedHeap::increment_old_marking_cycles_started() {
2262 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2263 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2264 "Wrong marking cycle count (started: %d, completed: %d)",
2265 _old_marking_cycles_started, _old_marking_cycles_completed);
2266
2267 _old_marking_cycles_started++;
2268 }
2269
2270 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2271 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2272
2273 // We assume that if concurrent == true, then the caller is a
2274 // concurrent thread that was joined the Suspendible Thread
2275 // Set. If there's ever a cheap way to check this, we should add an
2276 // assert here.
2277
2278 // Given that this method is called at the end of a Full GC or of a
2279 // concurrent cycle, and those can be nested (i.e., a Full GC can
2280 // interrupt a concurrent cycle), the number of full collections
2281 // completed should be either one (in the case where there was no
2282 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2283 // behind the number of full collections started.
2284
2285 // This is the case for the inner caller, i.e. a Full GC.
2286 assert(concurrent ||
2287 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2288 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2289 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2290 "is inconsistent with _old_marking_cycles_completed = %u",
2291 _old_marking_cycles_started, _old_marking_cycles_completed);
2292
2293 // This is the case for the outer caller, i.e. the concurrent cycle.
2294 assert(!concurrent ||
2295 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2296 "for outer caller (concurrent cycle): "
2297 "_old_marking_cycles_started = %u "
2298 "is inconsistent with _old_marking_cycles_completed = %u",
2299 _old_marking_cycles_started, _old_marking_cycles_completed);
2300
2301 _old_marking_cycles_completed += 1;
2302
2303 // We need to clear the "in_progress" flag in the CM thread before
2304 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2305 // is set) so that if a waiter requests another System.gc() it doesn't
2306 // incorrectly see that a marking cycle is still in progress.
2307 if (concurrent) {
2308 _cmThread->set_idle();
2309 }
2310
2311 // This notify_all() will ensure that a thread that called
2312 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2313 // and it's waiting for a full GC to finish will be woken up. It is
2314 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2315 FullGCCount_lock->notify_all();
2316 }
2317
2318 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2319 GCIdMarkAndRestore conc_gc_id_mark;
2320 collector_state()->set_concurrent_cycle_started(true);
2321 _gc_timer_cm->register_gc_start(start_time);
2322
2323 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2324 trace_heap_before_gc(_gc_tracer_cm);
2325 _cmThread->set_gc_id(GCId::current());
2326 }
2327
2328 void G1CollectedHeap::register_concurrent_cycle_end() {
2329 if (collector_state()->concurrent_cycle_started()) {
2330 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2331 if (_cm->has_aborted()) {
2332 _gc_tracer_cm->report_concurrent_mode_failure();
2333 }
2334
2335 _gc_timer_cm->register_gc_end();
2336 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2337
2338 // Clear state variables to prepare for the next concurrent cycle.
2339 collector_state()->set_concurrent_cycle_started(false);
2340 _heap_summary_sent = false;
2341 }
2342 }
2343
2344 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2345 if (collector_state()->concurrent_cycle_started()) {
2346 // This function can be called when:
2347 // the cleanup pause is run
2348 // the concurrent cycle is aborted before the cleanup pause.
2349 // the concurrent cycle is aborted after the cleanup pause,
2350 // but before the concurrent cycle end has been registered.
2351 // Make sure that we only send the heap information once.
2352 if (!_heap_summary_sent) {
2353 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2354 trace_heap_after_gc(_gc_tracer_cm);
2355 _heap_summary_sent = true;
2356 }
2357 }
2358 }
2359
2360 void G1CollectedHeap::collect(GCCause::Cause cause) {
2361 assert_heap_not_locked();
2362
2363 uint gc_count_before;
2364 uint old_marking_count_before;
2365 uint full_gc_count_before;
2366 bool retry_gc;
2367
2368 do {
2369 retry_gc = false;
2370
2371 {
2372 MutexLocker ml(Heap_lock);
2373
2374 // Read the GC count while holding the Heap_lock
2375 gc_count_before = total_collections();
2376 full_gc_count_before = total_full_collections();
2377 old_marking_count_before = _old_marking_cycles_started;
2378 }
2379
2380 if (should_do_concurrent_full_gc(cause)) {
2381 // Schedule an initial-mark evacuation pause that will start a
2382 // concurrent cycle. We're setting word_size to 0 which means that
2383 // we are not requesting a post-GC allocation.
2384 VM_G1IncCollectionPause op(gc_count_before,
2385 0, /* word_size */
2386 true, /* should_initiate_conc_mark */
2387 g1_policy()->max_pause_time_ms(),
2388 cause);
2389 op.set_allocation_context(AllocationContext::current());
2390
2391 VMThread::execute(&op);
2392 if (!op.pause_succeeded()) {
2393 if (old_marking_count_before == _old_marking_cycles_started) {
2394 retry_gc = op.should_retry_gc();
2395 } else {
2396 // A Full GC happened while we were trying to schedule the
2397 // initial-mark GC. No point in starting a new cycle given
2398 // that the whole heap was collected anyway.
2399 }
2400
2401 if (retry_gc) {
2402 if (GCLocker::is_active_and_needs_gc()) {
2403 GCLocker::stall_until_clear();
2404 }
2405 }
2406 }
2407 } else {
2408 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2409 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2410
2411 // Schedule a standard evacuation pause. We're setting word_size
2412 // to 0 which means that we are not requesting a post-GC allocation.
2413 VM_G1IncCollectionPause op(gc_count_before,
2414 0, /* word_size */
2415 false, /* should_initiate_conc_mark */
2416 g1_policy()->max_pause_time_ms(),
2417 cause);
2418 VMThread::execute(&op);
2419 } else {
2420 // Schedule a Full GC.
2421 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2422 VMThread::execute(&op);
2423 }
2424 }
2425 } while (retry_gc);
2426 }
2427
2428 bool G1CollectedHeap::is_in(const void* p) const {
2429 if (_hrm.reserved().contains(p)) {
2430 // Given that we know that p is in the reserved space,
2431 // heap_region_containing() should successfully
2432 // return the containing region.
2433 HeapRegion* hr = heap_region_containing(p);
2434 return hr->is_in(p);
2435 } else {
2436 return false;
2437 }
2438 }
2439
2440 #ifdef ASSERT
2441 bool G1CollectedHeap::is_in_exact(const void* p) const {
2442 bool contains = reserved_region().contains(p);
2443 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2444 if (contains && available) {
2445 return true;
2446 } else {
2447 return false;
2448 }
2449 }
2450 #endif
2451
2452 bool G1CollectedHeap::obj_in_cs(oop obj) {
2453 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2454 return r != NULL && r->in_collection_set();
2455 }
2456
2457 // Iteration functions.
2458
2459 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2460
2461 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2462 ExtendedOopClosure* _cl;
2463 public:
2464 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2465 bool doHeapRegion(HeapRegion* r) {
2466 if (!r->is_continues_humongous()) {
2467 r->oop_iterate(_cl);
2468 }
2469 return false;
2470 }
2471 };
2472
2473 // Iterates an ObjectClosure over all objects within a HeapRegion.
2474
2475 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2476 ObjectClosure* _cl;
2477 public:
2478 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2479 bool doHeapRegion(HeapRegion* r) {
2480 if (!r->is_continues_humongous()) {
2481 r->object_iterate(_cl);
2482 }
2483 return false;
2484 }
2485 };
2486
2487 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2488 IterateObjectClosureRegionClosure blk(cl);
2489 heap_region_iterate(&blk);
2490 }
2491
2492 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2493 _hrm.iterate(cl);
2494 }
2495
2496 void
2497 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2498 uint worker_id,
2499 HeapRegionClaimer *hrclaimer,
2500 bool concurrent) const {
2501 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2502 }
2503
2504 // Clear the cached CSet starting regions and (more importantly)
2505 // the time stamps. Called when we reset the GC time stamp.
2506 void G1CollectedHeap::clear_cset_start_regions() {
2507 assert(_worker_cset_start_region != NULL, "sanity");
2508 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2509
2510 for (uint i = 0; i < ParallelGCThreads; i++) {
2511 _worker_cset_start_region[i] = NULL;
2512 _worker_cset_start_region_time_stamp[i] = 0;
2513 }
2514 }
2515
2516 // Given the id of a worker, obtain or calculate a suitable
2517 // starting region for iterating over the current collection set.
2518 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2519 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2520
2521 HeapRegion* result = NULL;
2522 unsigned gc_time_stamp = get_gc_time_stamp();
2523
2524 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2525 // Cached starting region for current worker was set
2526 // during the current pause - so it's valid.
2527 // Note: the cached starting heap region may be NULL
2528 // (when the collection set is empty).
2529 result = _worker_cset_start_region[worker_i];
2530 assert(result == NULL || result->in_collection_set(), "sanity");
2531 return result;
2532 }
2533
2534 // The cached entry was not valid so let's calculate
2535 // a suitable starting heap region for this worker.
2536
2537 // We want the parallel threads to start their collection
2538 // set iteration at different collection set regions to
2539 // avoid contention.
2540 // If we have:
2541 // n collection set regions
2542 // p threads
2543 // Then thread t will start at region floor ((t * n) / p)
2544
2545 result = g1_policy()->collection_set();
2546 uint cs_size = g1_policy()->cset_region_length();
2547 uint active_workers = workers()->active_workers();
2548
2549 uint end_ind = (cs_size * worker_i) / active_workers;
2550 uint start_ind = 0;
2551
2552 if (worker_i > 0 &&
2553 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2554 // Previous workers starting region is valid
2555 // so let's iterate from there
2556 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2557 OrderAccess::loadload();
2558 result = _worker_cset_start_region[worker_i - 1];
2559 }
2560
2561 for (uint i = start_ind; i < end_ind; i++) {
2562 result = result->next_in_collection_set();
2563 }
2564
2565 // Note: the calculated starting heap region may be NULL
2566 // (when the collection set is empty).
2567 assert(result == NULL || result->in_collection_set(), "sanity");
2568 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2569 "should be updated only once per pause");
2570 _worker_cset_start_region[worker_i] = result;
2571 OrderAccess::storestore();
2572 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2573 return result;
2574 }
2575
2576 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2577 HeapRegion* r = g1_policy()->collection_set();
2578 while (r != NULL) {
2579 HeapRegion* next = r->next_in_collection_set();
2580 if (cl->doHeapRegion(r)) {
2581 cl->incomplete();
2582 return;
2583 }
2584 r = next;
2585 }
2586 }
2587
2588 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2589 HeapRegionClosure *cl) {
2590 if (r == NULL) {
2591 // The CSet is empty so there's nothing to do.
2592 return;
2593 }
2594
2595 assert(r->in_collection_set(),
2596 "Start region must be a member of the collection set.");
2597 HeapRegion* cur = r;
2598 while (cur != NULL) {
2599 HeapRegion* next = cur->next_in_collection_set();
2600 if (cl->doHeapRegion(cur) && false) {
2601 cl->incomplete();
2602 return;
2603 }
2604 cur = next;
2605 }
2606 cur = g1_policy()->collection_set();
2607 while (cur != r) {
2608 HeapRegion* next = cur->next_in_collection_set();
2609 if (cl->doHeapRegion(cur) && false) {
2610 cl->incomplete();
2611 return;
2612 }
2613 cur = next;
2614 }
2615 }
2616
2617 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2618 HeapRegion* result = _hrm.next_region_in_heap(from);
2619 while (result != NULL && result->is_pinned()) {
2620 result = _hrm.next_region_in_heap(result);
2621 }
2622 return result;
2623 }
2624
2625 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2626 HeapRegion* hr = heap_region_containing(addr);
2627 return hr->block_start(addr);
2628 }
2629
2630 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2631 HeapRegion* hr = heap_region_containing(addr);
2632 return hr->block_size(addr);
2633 }
2634
2635 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2636 HeapRegion* hr = heap_region_containing(addr);
2637 return hr->block_is_obj(addr);
2638 }
2639
2640 bool G1CollectedHeap::supports_tlab_allocation() const {
2641 return true;
2642 }
2643
2644 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2645 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2646 }
2647
2648 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2649 return young_list()->eden_used_bytes();
2650 }
2651
2652 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2653 // must be equal to the humongous object limit.
2654 size_t G1CollectedHeap::max_tlab_size() const {
2655 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2656 }
2657
2658 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2659 AllocationContext_t context = AllocationContext::current();
2660 return _allocator->unsafe_max_tlab_alloc(context);
2661 }
2662
2663 size_t G1CollectedHeap::max_capacity() const {
2664 return _hrm.reserved().byte_size();
2665 }
2666
2667 jlong G1CollectedHeap::millis_since_last_gc() {
2668 // assert(false, "NYI");
2669 return 0;
2670 }
2671
2672 void G1CollectedHeap::prepare_for_verify() {
2673 _verifier->prepare_for_verify();
2674 }
2675
2676 void G1CollectedHeap::verify(VerifyOption vo) {
2677 _verifier->verify(vo);
2678 }
2679
2680 class PrintRegionClosure: public HeapRegionClosure {
2681 outputStream* _st;
2682 public:
2683 PrintRegionClosure(outputStream* st) : _st(st) {}
2684 bool doHeapRegion(HeapRegion* r) {
2685 r->print_on(_st);
2686 return false;
2687 }
2688 };
2689
2690 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2691 const HeapRegion* hr,
2692 const VerifyOption vo) const {
2693 switch (vo) {
2694 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2695 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2696 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2697 default: ShouldNotReachHere();
2698 }
2699 return false; // keep some compilers happy
2700 }
2701
2702 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2703 const VerifyOption vo) const {
2704 switch (vo) {
2705 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2706 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2707 case VerifyOption_G1UseMarkWord: {
2708 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2709 return !obj->is_gc_marked() && !hr->is_archive();
2710 }
2711 default: ShouldNotReachHere();
2712 }
2713 return false; // keep some compilers happy
2714 }
2715
2716 void G1CollectedHeap::print_on(outputStream* st) const {
2717 st->print(" %-20s", "garbage-first heap");
2718 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2719 capacity()/K, used_unlocked()/K);
2720 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2721 p2i(_hrm.reserved().start()),
2722 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2723 p2i(_hrm.reserved().end()));
2724 st->cr();
2725 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2726 uint young_regions = _young_list->length();
2727 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2728 (size_t) young_regions * HeapRegion::GrainBytes / K);
2729 uint survivor_regions = g1_policy()->recorded_survivor_regions();
2730 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2731 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2732 st->cr();
2733 MetaspaceAux::print_on(st);
2734 }
2735
2736 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2737 print_on(st);
2738
2739 // Print the per-region information.
2740 st->cr();
2741 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2742 "HS=humongous(starts), HC=humongous(continues), "
2743 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2744 "AC=allocation context, "
2745 "TAMS=top-at-mark-start (previous, next)");
2746 PrintRegionClosure blk(st);
2747 heap_region_iterate(&blk);
2748 }
2749
2750 void G1CollectedHeap::print_on_error(outputStream* st) const {
2751 this->CollectedHeap::print_on_error(st);
2752
2753 if (_cm != NULL) {
2754 st->cr();
2755 _cm->print_on_error(st);
2756 }
2757 }
2758
2759 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2760 workers()->print_worker_threads_on(st);
2761 _cmThread->print_on(st);
2762 st->cr();
2763 _cm->print_worker_threads_on(st);
2764 _cg1r->print_worker_threads_on(st);
2765 if (G1StringDedup::is_enabled()) {
2766 G1StringDedup::print_worker_threads_on(st);
2767 }
2768 }
2769
2770 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2771 workers()->threads_do(tc);
2772 tc->do_thread(_cmThread);
2773 _cg1r->threads_do(tc);
2774 if (G1StringDedup::is_enabled()) {
2775 G1StringDedup::threads_do(tc);
2776 }
2777 }
2778
2779 void G1CollectedHeap::print_tracing_info() const {
2780 g1_rem_set()->print_summary_info();
2781 concurrent_mark()->print_summary_info();
2782 g1_policy()->print_yg_surv_rate_info();
2783 }
2784
2785 #ifndef PRODUCT
2786 // Helpful for debugging RSet issues.
2787
2788 class PrintRSetsClosure : public HeapRegionClosure {
2789 private:
2790 const char* _msg;
2791 size_t _occupied_sum;
2792
2793 public:
2794 bool doHeapRegion(HeapRegion* r) {
2795 HeapRegionRemSet* hrrs = r->rem_set();
2796 size_t occupied = hrrs->occupied();
2797 _occupied_sum += occupied;
2798
2799 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2800 if (occupied == 0) {
2801 tty->print_cr(" RSet is empty");
2802 } else {
2803 hrrs->print();
2804 }
2805 tty->print_cr("----------");
2806 return false;
2807 }
2808
2809 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2810 tty->cr();
2811 tty->print_cr("========================================");
2812 tty->print_cr("%s", msg);
2813 tty->cr();
2814 }
2815
2816 ~PrintRSetsClosure() {
2817 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2818 tty->print_cr("========================================");
2819 tty->cr();
2820 }
2821 };
2822
2823 void G1CollectedHeap::print_cset_rsets() {
2824 PrintRSetsClosure cl("Printing CSet RSets");
2825 collection_set_iterate(&cl);
2826 }
2827
2828 void G1CollectedHeap::print_all_rsets() {
2829 PrintRSetsClosure cl("Printing All RSets");;
2830 heap_region_iterate(&cl);
2831 }
2832 #endif // PRODUCT
2833
2834 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2835 YoungList* young_list = heap()->young_list();
2836
2837 size_t eden_used_bytes = young_list->eden_used_bytes();
2838 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2839
2840 size_t eden_capacity_bytes =
2841 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2842
2843 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2844 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes, num_regions());
2845 }
2846
2847 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2848 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2849 stats->unused(), stats->used(), stats->region_end_waste(),
2850 stats->regions_filled(), stats->direct_allocated(),
2851 stats->failure_used(), stats->failure_waste());
2852 }
2853
2854 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2855 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2856 gc_tracer->report_gc_heap_summary(when, heap_summary);
2857
2858 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2859 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2860 }
2861
2862
2863 G1CollectedHeap* G1CollectedHeap::heap() {
2864 CollectedHeap* heap = Universe::heap();
2865 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2866 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2867 return (G1CollectedHeap*)heap;
2868 }
2869
2870 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2871 // always_do_update_barrier = false;
2872 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2873 // Fill TLAB's and such
2874 accumulate_statistics_all_tlabs();
2875 ensure_parsability(true);
2876
2877 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2878 }
2879
2880 void G1CollectedHeap::gc_epilogue(bool full) {
2881 // we are at the end of the GC. Total collections has already been increased.
2882 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2883
2884 // FIXME: what is this about?
2885 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2886 // is set.
2887 #if defined(COMPILER2) || INCLUDE_JVMCI
2888 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2889 #endif
2890 // always_do_update_barrier = true;
2891
2892 resize_all_tlabs();
2893 allocation_context_stats().update(full);
2894
2895 // We have just completed a GC. Update the soft reference
2896 // policy with the new heap occupancy
2897 Universe::update_heap_info_at_gc();
2898 }
2899
2900 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2901 uint gc_count_before,
2902 bool* succeeded,
2903 GCCause::Cause gc_cause) {
2904 assert_heap_not_locked_and_not_at_safepoint();
2905 VM_G1IncCollectionPause op(gc_count_before,
2906 word_size,
2907 false, /* should_initiate_conc_mark */
2908 g1_policy()->max_pause_time_ms(),
2909 gc_cause);
2910
2911 op.set_allocation_context(AllocationContext::current());
2912 VMThread::execute(&op);
2913
2914 HeapWord* result = op.result();
2915 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2916 assert(result == NULL || ret_succeeded,
2917 "the result should be NULL if the VM did not succeed");
2918 *succeeded = ret_succeeded;
2919
2920 assert_heap_not_locked();
2921 return result;
2922 }
2923
2924 void
2925 G1CollectedHeap::doConcurrentMark() {
2926 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2927 if (!_cmThread->in_progress()) {
2928 _cmThread->set_started();
2929 CGC_lock->notify();
2930 }
2931 }
2932
2933 size_t G1CollectedHeap::pending_card_num() {
2934 size_t extra_cards = 0;
2935 JavaThread *curr = Threads::first();
2936 while (curr != NULL) {
2937 DirtyCardQueue& dcq = curr->dirty_card_queue();
2938 extra_cards += dcq.size();
2939 curr = curr->next();
2940 }
2941 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2942 size_t buffer_size = dcqs.buffer_size();
2943 size_t buffer_num = dcqs.completed_buffers_num();
2944
2945 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2946 // in bytes - not the number of 'entries'. We need to convert
2947 // into a number of cards.
2948 return (buffer_size * buffer_num + extra_cards) / oopSize;
2949 }
2950
2951 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2952 private:
2953 size_t _total_humongous;
2954 size_t _candidate_humongous;
2955
2956 DirtyCardQueue _dcq;
2957
2958 // We don't nominate objects with many remembered set entries, on
2959 // the assumption that such objects are likely still live.
2960 bool is_remset_small(HeapRegion* region) const {
2961 HeapRegionRemSet* const rset = region->rem_set();
2962 return G1EagerReclaimHumongousObjectsWithStaleRefs
2963 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2964 : rset->is_empty();
2965 }
2966
2967 bool is_typeArray_region(HeapRegion* region) const {
2968 return oop(region->bottom())->is_typeArray();
2969 }
2970
2971 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2972 assert(region->is_starts_humongous(), "Must start a humongous object");
2973
2974 // Candidate selection must satisfy the following constraints
2975 // while concurrent marking is in progress:
2976 //
2977 // * In order to maintain SATB invariants, an object must not be
2978 // reclaimed if it was allocated before the start of marking and
2979 // has not had its references scanned. Such an object must have
2980 // its references (including type metadata) scanned to ensure no
2981 // live objects are missed by the marking process. Objects
2982 // allocated after the start of concurrent marking don't need to
2983 // be scanned.
2984 //
2985 // * An object must not be reclaimed if it is on the concurrent
2986 // mark stack. Objects allocated after the start of concurrent
2987 // marking are never pushed on the mark stack.
2988 //
2989 // Nominating only objects allocated after the start of concurrent
2990 // marking is sufficient to meet both constraints. This may miss
2991 // some objects that satisfy the constraints, but the marking data
2992 // structures don't support efficiently performing the needed
2993 // additional tests or scrubbing of the mark stack.
2994 //
2995 // However, we presently only nominate is_typeArray() objects.
2996 // A humongous object containing references induces remembered
2997 // set entries on other regions. In order to reclaim such an
2998 // object, those remembered sets would need to be cleaned up.
2999 //
3000 // We also treat is_typeArray() objects specially, allowing them
3001 // to be reclaimed even if allocated before the start of
3002 // concurrent mark. For this we rely on mark stack insertion to
3003 // exclude is_typeArray() objects, preventing reclaiming an object
3004 // that is in the mark stack. We also rely on the metadata for
3005 // such objects to be built-in and so ensured to be kept live.
3006 // Frequent allocation and drop of large binary blobs is an
3007 // important use case for eager reclaim, and this special handling
3008 // may reduce needed headroom.
3009
3010 return is_typeArray_region(region) && is_remset_small(region);
3011 }
3012
3013 public:
3014 RegisterHumongousWithInCSetFastTestClosure()
3015 : _total_humongous(0),
3016 _candidate_humongous(0),
3017 _dcq(&JavaThread::dirty_card_queue_set()) {
3018 }
3019
3020 virtual bool doHeapRegion(HeapRegion* r) {
3021 if (!r->is_starts_humongous()) {
3022 return false;
3023 }
3024 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3025
3026 bool is_candidate = humongous_region_is_candidate(g1h, r);
3027 uint rindex = r->hrm_index();
3028 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3029 if (is_candidate) {
3030 _candidate_humongous++;
3031 g1h->register_humongous_region_with_cset(rindex);
3032 // Is_candidate already filters out humongous object with large remembered sets.
3033 // If we have a humongous object with a few remembered sets, we simply flush these
3034 // remembered set entries into the DCQS. That will result in automatic
3035 // re-evaluation of their remembered set entries during the following evacuation
3036 // phase.
3037 if (!r->rem_set()->is_empty()) {
3038 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3039 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3040 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3041 HeapRegionRemSetIterator hrrs(r->rem_set());
3042 size_t card_index;
3043 while (hrrs.has_next(card_index)) {
3044 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3045 // The remembered set might contain references to already freed
3046 // regions. Filter out such entries to avoid failing card table
3047 // verification.
3048 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3049 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3050 *card_ptr = CardTableModRefBS::dirty_card_val();
3051 _dcq.enqueue(card_ptr);
3052 }
3053 }
3054 }
3055 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3056 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3057 hrrs.n_yielded(), r->rem_set()->occupied());
3058 r->rem_set()->clear_locked();
3059 }
3060 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3061 }
3062 _total_humongous++;
3063
3064 return false;
3065 }
3066
3067 size_t total_humongous() const { return _total_humongous; }
3068 size_t candidate_humongous() const { return _candidate_humongous; }
3069
3070 void flush_rem_set_entries() { _dcq.flush(); }
3071 };
3072
3073 void G1CollectedHeap::register_humongous_regions_with_cset() {
3074 if (!G1EagerReclaimHumongousObjects) {
3075 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3076 return;
3077 }
3078 double time = os::elapsed_counter();
3079
3080 // Collect reclaim candidate information and register candidates with cset.
3081 RegisterHumongousWithInCSetFastTestClosure cl;
3082 heap_region_iterate(&cl);
3083
3084 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3085 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3086 cl.total_humongous(),
3087 cl.candidate_humongous());
3088 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3089
3090 // Finally flush all remembered set entries to re-check into the global DCQS.
3091 cl.flush_rem_set_entries();
3092 }
3093
3094 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3095 public:
3096 bool doHeapRegion(HeapRegion* hr) {
3097 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3098 hr->verify_rem_set();
3099 }
3100 return false;
3101 }
3102 };
3103
3104 #ifdef ASSERT
3105 class VerifyCSetClosure: public HeapRegionClosure {
3106 public:
3107 bool doHeapRegion(HeapRegion* hr) {
3108 // Here we check that the CSet region's RSet is ready for parallel
3109 // iteration. The fields that we'll verify are only manipulated
3110 // when the region is part of a CSet and is collected. Afterwards,
3111 // we reset these fields when we clear the region's RSet (when the
3112 // region is freed) so they are ready when the region is
3113 // re-allocated. The only exception to this is if there's an
3114 // evacuation failure and instead of freeing the region we leave
3115 // it in the heap. In that case, we reset these fields during
3116 // evacuation failure handling.
3117 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3118
3119 // Here's a good place to add any other checks we'd like to
3120 // perform on CSet regions.
3121 return false;
3122 }
3123 };
3124 #endif // ASSERT
3125
3126 uint G1CollectedHeap::num_task_queues() const {
3127 return _task_queues->size();
3128 }
3129
3130 #if TASKQUEUE_STATS
3131 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3132 st->print_raw_cr("GC Task Stats");
3133 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3134 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3135 }
3136
3137 void G1CollectedHeap::print_taskqueue_stats() const {
3138 if (!log_develop_is_enabled(Trace, gc, task, stats)) {
3139 return;
3140 }
3141 LogHandle(gc, task, stats) log;
3142 ResourceMark rm;
3143 outputStream* st = log.trace_stream();
3144
3145 print_taskqueue_stats_hdr(st);
3146
3147 TaskQueueStats totals;
3148 const uint n = num_task_queues();
3149 for (uint i = 0; i < n; ++i) {
3150 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3151 totals += task_queue(i)->stats;
3152 }
3153 st->print_raw("tot "); totals.print(st); st->cr();
3154
3155 DEBUG_ONLY(totals.verify());
3156 }
3157
3158 void G1CollectedHeap::reset_taskqueue_stats() {
3159 const uint n = num_task_queues();
3160 for (uint i = 0; i < n; ++i) {
3161 task_queue(i)->stats.reset();
3162 }
3163 }
3164 #endif // TASKQUEUE_STATS
3165
3166 void G1CollectedHeap::wait_for_root_region_scanning() {
3167 double scan_wait_start = os::elapsedTime();
3168 // We have to wait until the CM threads finish scanning the
3169 // root regions as it's the only way to ensure that all the
3170 // objects on them have been correctly scanned before we start
3171 // moving them during the GC.
3172 bool waited = _cm->root_regions()->wait_until_scan_finished();
3173 double wait_time_ms = 0.0;
3174 if (waited) {
3175 double scan_wait_end = os::elapsedTime();
3176 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3177 }
3178 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3179 }
3180
3181 bool
3182 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3183 assert_at_safepoint(true /* should_be_vm_thread */);
3184 guarantee(!is_gc_active(), "collection is not reentrant");
3185
3186 if (GCLocker::check_active_before_gc()) {
3187 return false;
3188 }
3189
3190 _gc_timer_stw->register_gc_start();
3191
3192 GCIdMark gc_id_mark;
3193 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3194
3195 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3196 ResourceMark rm;
3197
3198 wait_for_root_region_scanning();
3199
3200 print_heap_before_gc();
3201 trace_heap_before_gc(_gc_tracer_stw);
3202
3203 _verifier->verify_region_sets_optional();
3204 _verifier->verify_dirty_young_regions();
3205
3206 // This call will decide whether this pause is an initial-mark
3207 // pause. If it is, during_initial_mark_pause() will return true
3208 // for the duration of this pause.
3209 g1_policy()->decide_on_conc_mark_initiation();
3210
3211 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3212 assert(!collector_state()->during_initial_mark_pause() ||
3213 collector_state()->gcs_are_young(), "sanity");
3214
3215 // We also do not allow mixed GCs during marking.
3216 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3217
3218 // Record whether this pause is an initial mark. When the current
3219 // thread has completed its logging output and it's safe to signal
3220 // the CM thread, the flag's value in the policy has been reset.
3221 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3222
3223 // Inner scope for scope based logging, timers, and stats collection
3224 {
3225 EvacuationInfo evacuation_info;
3226
3227 if (collector_state()->during_initial_mark_pause()) {
3228 // We are about to start a marking cycle, so we increment the
3229 // full collection counter.
3230 increment_old_marking_cycles_started();
3231 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3232 }
3233
3234 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3235
3236 GCTraceCPUTime tcpu;
3237
3238 FormatBuffer<> gc_string("Pause ");
3239 if (collector_state()->during_initial_mark_pause()) {
3240 gc_string.append("Initial Mark");
3241 } else if (collector_state()->gcs_are_young()) {
3242 gc_string.append("Young");
3243 } else {
3244 gc_string.append("Mixed");
3245 }
3246 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3247
3248 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3249 workers()->active_workers(),
3250 Threads::number_of_non_daemon_threads());
3251 workers()->set_active_workers(active_workers);
3252
3253 g1_policy()->note_gc_start(active_workers);
3254
3255 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3256 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3257
3258 // If the secondary_free_list is not empty, append it to the
3259 // free_list. No need to wait for the cleanup operation to finish;
3260 // the region allocation code will check the secondary_free_list
3261 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3262 // set, skip this step so that the region allocation code has to
3263 // get entries from the secondary_free_list.
3264 if (!G1StressConcRegionFreeing) {
3265 append_secondary_free_list_if_not_empty_with_lock();
3266 }
3267
3268 G1HeapTransition heap_transition(this);
3269 size_t heap_used_bytes_before_gc = used();
3270
3271 assert(check_young_list_well_formed(), "young list should be well formed");
3272
3273 // Don't dynamically change the number of GC threads this early. A value of
3274 // 0 is used to indicate serial work. When parallel work is done,
3275 // it will be set.
3276
3277 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3278 IsGCActiveMark x;
3279
3280 gc_prologue(false);
3281 increment_total_collections(false /* full gc */);
3282 increment_gc_time_stamp();
3283
3284 if (VerifyRememberedSets) {
3285 log_info(gc, verify)("[Verifying RemSets before GC]");
3286 VerifyRegionRemSetClosure v_cl;
3287 heap_region_iterate(&v_cl);
3288 }
3289
3290 _verifier->verify_before_gc();
3291
3292 _verifier->check_bitmaps("GC Start");
3293
3294 #if defined(COMPILER2) || INCLUDE_JVMCI
3295 DerivedPointerTable::clear();
3296 #endif
3297
3298 // Please see comment in g1CollectedHeap.hpp and
3299 // G1CollectedHeap::ref_processing_init() to see how
3300 // reference processing currently works in G1.
3301
3302 // Enable discovery in the STW reference processor
3303 if (g1_policy()->should_process_references()) {
3304 ref_processor_stw()->enable_discovery();
3305 } else {
3306 ref_processor_stw()->disable_discovery();
3307 }
3308
3309 {
3310 // We want to temporarily turn off discovery by the
3311 // CM ref processor, if necessary, and turn it back on
3312 // on again later if we do. Using a scoped
3313 // NoRefDiscovery object will do this.
3314 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3315
3316 // Forget the current alloc region (we might even choose it to be part
3317 // of the collection set!).
3318 _allocator->release_mutator_alloc_region();
3319
3320 // This timing is only used by the ergonomics to handle our pause target.
3321 // It is unclear why this should not include the full pause. We will
3322 // investigate this in CR 7178365.
3323 //
3324 // Preserving the old comment here if that helps the investigation:
3325 //
3326 // The elapsed time induced by the start time below deliberately elides
3327 // the possible verification above.
3328 double sample_start_time_sec = os::elapsedTime();
3329
3330 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3331
3332 if (collector_state()->during_initial_mark_pause()) {
3333 concurrent_mark()->checkpointRootsInitialPre();
3334 }
3335
3336 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3337 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3338
3339 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3340
3341 // Make sure the remembered sets are up to date. This needs to be
3342 // done before register_humongous_regions_with_cset(), because the
3343 // remembered sets are used there to choose eager reclaim candidates.
3344 // If the remembered sets are not up to date we might miss some
3345 // entries that need to be handled.
3346 g1_rem_set()->cleanupHRRS();
3347
3348 register_humongous_regions_with_cset();
3349
3350 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3351
3352 _cm->note_start_of_gc();
3353 // We call this after finalize_cset() to
3354 // ensure that the CSet has been finalized.
3355 _cm->verify_no_cset_oops();
3356
3357 if (_hr_printer.is_active()) {
3358 HeapRegion* hr = g1_policy()->collection_set();
3359 while (hr != NULL) {
3360 _hr_printer.cset(hr);
3361 hr = hr->next_in_collection_set();
3362 }
3363 }
3364
3365 #ifdef ASSERT
3366 VerifyCSetClosure cl;
3367 collection_set_iterate(&cl);
3368 #endif // ASSERT
3369
3370 // Initialize the GC alloc regions.
3371 _allocator->init_gc_alloc_regions(evacuation_info);
3372
3373 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3374 pre_evacuate_collection_set();
3375
3376 // Actually do the work...
3377 evacuate_collection_set(evacuation_info, &per_thread_states);
3378
3379 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3380
3381 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3382 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3383
3384 eagerly_reclaim_humongous_regions();
3385
3386 g1_policy()->clear_collection_set();
3387
3388 // Start a new incremental collection set for the next pause.
3389 g1_policy()->start_incremental_cset_building();
3390
3391 clear_cset_fast_test();
3392
3393 _young_list->reset_sampled_info();
3394
3395 // Don't check the whole heap at this point as the
3396 // GC alloc regions from this pause have been tagged
3397 // as survivors and moved on to the survivor list.
3398 // Survivor regions will fail the !is_young() check.
3399 assert(check_young_list_empty(false /* check_heap */),
3400 "young list should be empty");
3401
3402 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3403 _young_list->first_survivor_region(),
3404 _young_list->last_survivor_region());
3405
3406 _young_list->reset_auxilary_lists();
3407
3408 if (evacuation_failed()) {
3409 set_used(recalculate_used());
3410 if (_archive_allocator != NULL) {
3411 _archive_allocator->clear_used();
3412 }
3413 for (uint i = 0; i < ParallelGCThreads; i++) {
3414 if (_evacuation_failed_info_array[i].has_failed()) {
3415 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3416 }
3417 }
3418 } else {
3419 // The "used" of the the collection set have already been subtracted
3420 // when they were freed. Add in the bytes evacuated.
3421 increase_used(g1_policy()->bytes_copied_during_gc());
3422 }
3423
3424 if (collector_state()->during_initial_mark_pause()) {
3425 // We have to do this before we notify the CM threads that
3426 // they can start working to make sure that all the
3427 // appropriate initialization is done on the CM object.
3428 concurrent_mark()->checkpointRootsInitialPost();
3429 collector_state()->set_mark_in_progress(true);
3430 // Note that we don't actually trigger the CM thread at
3431 // this point. We do that later when we're sure that
3432 // the current thread has completed its logging output.
3433 }
3434
3435 allocate_dummy_regions();
3436
3437 _allocator->init_mutator_alloc_region();
3438
3439 {
3440 size_t expand_bytes = g1_policy()->expansion_amount();
3441 if (expand_bytes > 0) {
3442 size_t bytes_before = capacity();
3443 // No need for an ergo logging here,
3444 // expansion_amount() does this when it returns a value > 0.
3445 double expand_ms;
3446 if (!expand(expand_bytes, &expand_ms)) {
3447 // We failed to expand the heap. Cannot do anything about it.
3448 }
3449 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3450 }
3451 }
3452
3453 // We redo the verification but now wrt to the new CSet which
3454 // has just got initialized after the previous CSet was freed.
3455 _cm->verify_no_cset_oops();
3456 _cm->note_end_of_gc();
3457
3458 // This timing is only used by the ergonomics to handle our pause target.
3459 // It is unclear why this should not include the full pause. We will
3460 // investigate this in CR 7178365.
3461 double sample_end_time_sec = os::elapsedTime();
3462 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3463 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3464 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3465
3466 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3467 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3468
3469 MemoryService::track_memory_usage();
3470
3471 // In prepare_for_verify() below we'll need to scan the deferred
3472 // update buffers to bring the RSets up-to-date if
3473 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3474 // the update buffers we'll probably need to scan cards on the
3475 // regions we just allocated to (i.e., the GC alloc
3476 // regions). However, during the last GC we called
3477 // set_saved_mark() on all the GC alloc regions, so card
3478 // scanning might skip the [saved_mark_word()...top()] area of
3479 // those regions (i.e., the area we allocated objects into
3480 // during the last GC). But it shouldn't. Given that
3481 // saved_mark_word() is conditional on whether the GC time stamp
3482 // on the region is current or not, by incrementing the GC time
3483 // stamp here we invalidate all the GC time stamps on all the
3484 // regions and saved_mark_word() will simply return top() for
3485 // all the regions. This is a nicer way of ensuring this rather
3486 // than iterating over the regions and fixing them. In fact, the
3487 // GC time stamp increment here also ensures that
3488 // saved_mark_word() will return top() between pauses, i.e.,
3489 // during concurrent refinement. So we don't need the
3490 // is_gc_active() check to decided which top to use when
3491 // scanning cards (see CR 7039627).
3492 increment_gc_time_stamp();
3493
3494 if (VerifyRememberedSets) {
3495 log_info(gc, verify)("[Verifying RemSets after GC]");
3496 VerifyRegionRemSetClosure v_cl;
3497 heap_region_iterate(&v_cl);
3498 }
3499
3500 _verifier->verify_after_gc();
3501 _verifier->check_bitmaps("GC End");
3502
3503 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3504 ref_processor_stw()->verify_no_references_recorded();
3505
3506 // CM reference discovery will be re-enabled if necessary.
3507 }
3508
3509 #ifdef TRACESPINNING
3510 ParallelTaskTerminator::print_termination_counts();
3511 #endif
3512
3513 gc_epilogue(false);
3514 }
3515
3516 // Print the remainder of the GC log output.
3517 if (evacuation_failed()) {
3518 log_info(gc)("To-space exhausted");
3519 }
3520
3521 g1_policy()->print_phases();
3522 heap_transition.print();
3523
3524 // It is not yet to safe to tell the concurrent mark to
3525 // start as we have some optional output below. We don't want the
3526 // output from the concurrent mark thread interfering with this
3527 // logging output either.
3528
3529 _hrm.verify_optional();
3530 _verifier->verify_region_sets_optional();
3531
3532 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3533 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3534
3535 print_heap_after_gc();
3536 trace_heap_after_gc(_gc_tracer_stw);
3537
3538 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3539 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3540 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3541 // before any GC notifications are raised.
3542 g1mm()->update_sizes();
3543
3544 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3545 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3546 _gc_timer_stw->register_gc_end();
3547 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3548 }
3549 // It should now be safe to tell the concurrent mark thread to start
3550 // without its logging output interfering with the logging output
3551 // that came from the pause.
3552
3553 if (should_start_conc_mark) {
3554 // CAUTION: after the doConcurrentMark() call below,
3555 // the concurrent marking thread(s) could be running
3556 // concurrently with us. Make sure that anything after
3557 // this point does not assume that we are the only GC thread
3558 // running. Note: of course, the actual marking work will
3559 // not start until the safepoint itself is released in
3560 // SuspendibleThreadSet::desynchronize().
3561 doConcurrentMark();
3562 }
3563
3564 return true;
3565 }
3566
3567 void G1CollectedHeap::restore_preserved_marks() {
3568 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3569 workers()->run_task(&rpm_task);
3570 }
3571
3572 void G1CollectedHeap::remove_self_forwarding_pointers() {
3573 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3574 workers()->run_task(&rsfp_task);
3575 }
3576
3577 void G1CollectedHeap::restore_after_evac_failure() {
3578 double remove_self_forwards_start = os::elapsedTime();
3579
3580 remove_self_forwarding_pointers();
3581 restore_preserved_marks();
3582
3583 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3584 }
3585
3586 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3587 if (!_evacuation_failed) {
3588 _evacuation_failed = true;
3589 }
3590
3591 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3592
3593 // We want to call the "for_promotion_failure" version only in the
3594 // case of a promotion failure.
3595 if (m->must_be_preserved_for_promotion_failure(obj)) {
3596 OopAndMarkOop elem(obj, m);
3597 _preserved_objs[worker_id].push(elem);
3598 }
3599 }
3600
3601 bool G1ParEvacuateFollowersClosure::offer_termination() {
3602 G1ParScanThreadState* const pss = par_scan_state();
3603 start_term_time();
3604 const bool res = terminator()->offer_termination();
3605 end_term_time();
3606 return res;
3607 }
3608
3609 void G1ParEvacuateFollowersClosure::do_void() {
3610 G1ParScanThreadState* const pss = par_scan_state();
3611 pss->trim_queue();
3612 do {
3613 pss->steal_and_trim_queue(queues());
3614 } while (!offer_termination());
3615 }
3616
3617 class G1ParTask : public AbstractGangTask {
3618 protected:
3619 G1CollectedHeap* _g1h;
3620 G1ParScanThreadStateSet* _pss;
3621 RefToScanQueueSet* _queues;
3622 G1RootProcessor* _root_processor;
3623 ParallelTaskTerminator _terminator;
3624 uint _n_workers;
3625
3626 public:
3627 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3628 : AbstractGangTask("G1 collection"),
3629 _g1h(g1h),
3630 _pss(per_thread_states),
3631 _queues(task_queues),
3632 _root_processor(root_processor),
3633 _terminator(n_workers, _queues),
3634 _n_workers(n_workers)
3635 {}
3636
3637 void work(uint worker_id) {
3638 if (worker_id >= _n_workers) return; // no work needed this round
3639
3640 double start_sec = os::elapsedTime();
3641 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3642
3643 {
3644 ResourceMark rm;
3645 HandleMark hm;
3646
3647 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3648
3649 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3650 pss->set_ref_processor(rp);
3651
3652 double start_strong_roots_sec = os::elapsedTime();
3653
3654 _root_processor->evacuate_roots(pss->closures(), worker_id);
3655
3656 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3657
3658 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3659 // treating the nmethods visited to act as roots for concurrent marking.
3660 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3661 // objects copied by the current evacuation.
3662 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3663 pss->closures()->weak_codeblobs(),
3664 worker_id);
3665
3666 _pss->add_cards_scanned(worker_id, cards_scanned);
3667
3668 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3669
3670 double term_sec = 0.0;
3671 size_t evac_term_attempts = 0;
3672 {
3673 double start = os::elapsedTime();
3674 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3675 evac.do_void();
3676
3677 evac_term_attempts = evac.term_attempts();
3678 term_sec = evac.term_time();
3679 double elapsed_sec = os::elapsedTime() - start;
3680 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3681 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3682 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3683 }
3684
3685 assert(pss->queue_is_empty(), "should be empty");
3686
3687 if (log_is_enabled(Debug, gc, task, stats)) {
3688 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3689 size_t lab_waste;
3690 size_t lab_undo_waste;
3691 pss->waste(lab_waste, lab_undo_waste);
3692 _g1h->print_termination_stats(worker_id,
3693 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3694 strong_roots_sec * 1000.0, /* strong roots time */
3695 term_sec * 1000.0, /* evac term time */
3696 evac_term_attempts, /* evac term attempts */
3697 lab_waste, /* alloc buffer waste */
3698 lab_undo_waste /* undo waste */
3699 );
3700 }
3701
3702 // Close the inner scope so that the ResourceMark and HandleMark
3703 // destructors are executed here and are included as part of the
3704 // "GC Worker Time".
3705 }
3706 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3707 }
3708 };
3709
3710 void G1CollectedHeap::print_termination_stats_hdr() {
3711 log_debug(gc, task, stats)("GC Termination Stats");
3712 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3713 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3714 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3715 }
3716
3717 void G1CollectedHeap::print_termination_stats(uint worker_id,
3718 double elapsed_ms,
3719 double strong_roots_ms,
3720 double term_ms,
3721 size_t term_attempts,
3722 size_t alloc_buffer_waste,
3723 size_t undo_waste) const {
3724 log_debug(gc, task, stats)
3725 ("%3d %9.2f %9.2f %6.2f "
3726 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3727 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3728 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3729 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3730 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3731 alloc_buffer_waste * HeapWordSize / K,
3732 undo_waste * HeapWordSize / K);
3733 }
3734
3735 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3736 private:
3737 BoolObjectClosure* _is_alive;
3738 int _initial_string_table_size;
3739 int _initial_symbol_table_size;
3740
3741 bool _process_strings;
3742 int _strings_processed;
3743 int _strings_removed;
3744
3745 bool _process_symbols;
3746 int _symbols_processed;
3747 int _symbols_removed;
3748
3749 public:
3750 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3751 AbstractGangTask("String/Symbol Unlinking"),
3752 _is_alive(is_alive),
3753 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3754 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3755
3756 _initial_string_table_size = StringTable::the_table()->table_size();
3757 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3758 if (process_strings) {
3759 StringTable::clear_parallel_claimed_index();
3760 }
3761 if (process_symbols) {
3762 SymbolTable::clear_parallel_claimed_index();
3763 }
3764 }
3765
3766 ~G1StringSymbolTableUnlinkTask() {
3767 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3768 "claim value %d after unlink less than initial string table size %d",
3769 StringTable::parallel_claimed_index(), _initial_string_table_size);
3770 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3771 "claim value %d after unlink less than initial symbol table size %d",
3772 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3773
3774 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3775 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3776 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3777 strings_processed(), strings_removed(),
3778 symbols_processed(), symbols_removed());
3779 }
3780
3781 void work(uint worker_id) {
3782 int strings_processed = 0;
3783 int strings_removed = 0;
3784 int symbols_processed = 0;
3785 int symbols_removed = 0;
3786 if (_process_strings) {
3787 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3788 Atomic::add(strings_processed, &_strings_processed);
3789 Atomic::add(strings_removed, &_strings_removed);
3790 }
3791 if (_process_symbols) {
3792 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3793 Atomic::add(symbols_processed, &_symbols_processed);
3794 Atomic::add(symbols_removed, &_symbols_removed);
3795 }
3796 }
3797
3798 size_t strings_processed() const { return (size_t)_strings_processed; }
3799 size_t strings_removed() const { return (size_t)_strings_removed; }
3800
3801 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3802 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3803 };
3804
3805 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3806 private:
3807 static Monitor* _lock;
3808
3809 BoolObjectClosure* const _is_alive;
3810 const bool _unloading_occurred;
3811 const uint _num_workers;
3812
3813 // Variables used to claim nmethods.
3814 nmethod* _first_nmethod;
3815 volatile nmethod* _claimed_nmethod;
3816
3817 // The list of nmethods that need to be processed by the second pass.
3818 volatile nmethod* _postponed_list;
3819 volatile uint _num_entered_barrier;
3820
3821 public:
3822 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3823 _is_alive(is_alive),
3824 _unloading_occurred(unloading_occurred),
3825 _num_workers(num_workers),
3826 _first_nmethod(NULL),
3827 _claimed_nmethod(NULL),
3828 _postponed_list(NULL),
3829 _num_entered_barrier(0)
3830 {
3831 nmethod::increase_unloading_clock();
3832 // Get first alive nmethod
3833 NMethodIterator iter = NMethodIterator();
3834 if(iter.next_alive()) {
3835 _first_nmethod = iter.method();
3836 }
3837 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3838 }
3839
3840 ~G1CodeCacheUnloadingTask() {
3841 CodeCache::verify_clean_inline_caches();
3842
3843 CodeCache::set_needs_cache_clean(false);
3844 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3845
3846 CodeCache::verify_icholder_relocations();
3847 }
3848
3849 private:
3850 void add_to_postponed_list(nmethod* nm) {
3851 nmethod* old;
3852 do {
3853 old = (nmethod*)_postponed_list;
3854 nm->set_unloading_next(old);
3855 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3856 }
3857
3858 void clean_nmethod(nmethod* nm) {
3859 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3860
3861 if (postponed) {
3862 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3863 add_to_postponed_list(nm);
3864 }
3865
3866 // Mark that this thread has been cleaned/unloaded.
3867 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3868 nm->set_unloading_clock(nmethod::global_unloading_clock());
3869 }
3870
3871 void clean_nmethod_postponed(nmethod* nm) {
3872 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3873 }
3874
3875 static const int MaxClaimNmethods = 16;
3876
3877 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3878 nmethod* first;
3879 NMethodIterator last;
3880
3881 do {
3882 *num_claimed_nmethods = 0;
3883
3884 first = (nmethod*)_claimed_nmethod;
3885 last = NMethodIterator(first);
3886
3887 if (first != NULL) {
3888
3889 for (int i = 0; i < MaxClaimNmethods; i++) {
3890 if (!last.next_alive()) {
3891 break;
3892 }
3893 claimed_nmethods[i] = last.method();
3894 (*num_claimed_nmethods)++;
3895 }
3896 }
3897
3898 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3899 }
3900
3901 nmethod* claim_postponed_nmethod() {
3902 nmethod* claim;
3903 nmethod* next;
3904
3905 do {
3906 claim = (nmethod*)_postponed_list;
3907 if (claim == NULL) {
3908 return NULL;
3909 }
3910
3911 next = claim->unloading_next();
3912
3913 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3914
3915 return claim;
3916 }
3917
3918 public:
3919 // Mark that we're done with the first pass of nmethod cleaning.
3920 void barrier_mark(uint worker_id) {
3921 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3922 _num_entered_barrier++;
3923 if (_num_entered_barrier == _num_workers) {
3924 ml.notify_all();
3925 }
3926 }
3927
3928 // See if we have to wait for the other workers to
3929 // finish their first-pass nmethod cleaning work.
3930 void barrier_wait(uint worker_id) {
3931 if (_num_entered_barrier < _num_workers) {
3932 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3933 while (_num_entered_barrier < _num_workers) {
3934 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3935 }
3936 }
3937 }
3938
3939 // Cleaning and unloading of nmethods. Some work has to be postponed
3940 // to the second pass, when we know which nmethods survive.
3941 void work_first_pass(uint worker_id) {
3942 // The first nmethods is claimed by the first worker.
3943 if (worker_id == 0 && _first_nmethod != NULL) {
3944 clean_nmethod(_first_nmethod);
3945 _first_nmethod = NULL;
3946 }
3947
3948 int num_claimed_nmethods;
3949 nmethod* claimed_nmethods[MaxClaimNmethods];
3950
3951 while (true) {
3952 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3953
3954 if (num_claimed_nmethods == 0) {
3955 break;
3956 }
3957
3958 for (int i = 0; i < num_claimed_nmethods; i++) {
3959 clean_nmethod(claimed_nmethods[i]);
3960 }
3961 }
3962 }
3963
3964 void work_second_pass(uint worker_id) {
3965 nmethod* nm;
3966 // Take care of postponed nmethods.
3967 while ((nm = claim_postponed_nmethod()) != NULL) {
3968 clean_nmethod_postponed(nm);
3969 }
3970 }
3971 };
3972
3973 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3974
3975 class G1KlassCleaningTask : public StackObj {
3976 BoolObjectClosure* _is_alive;
3977 volatile jint _clean_klass_tree_claimed;
3978 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3979
3980 public:
3981 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3982 _is_alive(is_alive),
3983 _clean_klass_tree_claimed(0),
3984 _klass_iterator() {
3985 }
3986
3987 private:
3988 bool claim_clean_klass_tree_task() {
3989 if (_clean_klass_tree_claimed) {
3990 return false;
3991 }
3992
3993 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3994 }
3995
3996 InstanceKlass* claim_next_klass() {
3997 Klass* klass;
3998 do {
3999 klass =_klass_iterator.next_klass();
4000 } while (klass != NULL && !klass->is_instance_klass());
4001
4002 // this can be null so don't call InstanceKlass::cast
4003 return static_cast<InstanceKlass*>(klass);
4004 }
4005
4006 public:
4007
4008 void clean_klass(InstanceKlass* ik) {
4009 ik->clean_weak_instanceklass_links(_is_alive);
4010 }
4011
4012 void work() {
4013 ResourceMark rm;
4014
4015 // One worker will clean the subklass/sibling klass tree.
4016 if (claim_clean_klass_tree_task()) {
4017 Klass::clean_subklass_tree(_is_alive);
4018 }
4019
4020 // All workers will help cleaning the classes,
4021 InstanceKlass* klass;
4022 while ((klass = claim_next_klass()) != NULL) {
4023 clean_klass(klass);
4024 }
4025 }
4026 };
4027
4028 // To minimize the remark pause times, the tasks below are done in parallel.
4029 class G1ParallelCleaningTask : public AbstractGangTask {
4030 private:
4031 G1StringSymbolTableUnlinkTask _string_symbol_task;
4032 G1CodeCacheUnloadingTask _code_cache_task;
4033 G1KlassCleaningTask _klass_cleaning_task;
4034
4035 public:
4036 // The constructor is run in the VMThread.
4037 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4038 AbstractGangTask("Parallel Cleaning"),
4039 _string_symbol_task(is_alive, process_strings, process_symbols),
4040 _code_cache_task(num_workers, is_alive, unloading_occurred),
4041 _klass_cleaning_task(is_alive) {
4042 }
4043
4044 // The parallel work done by all worker threads.
4045 void work(uint worker_id) {
4046 // Do first pass of code cache cleaning.
4047 _code_cache_task.work_first_pass(worker_id);
4048
4049 // Let the threads mark that the first pass is done.
4050 _code_cache_task.barrier_mark(worker_id);
4051
4052 // Clean the Strings and Symbols.
4053 _string_symbol_task.work(worker_id);
4054
4055 // Wait for all workers to finish the first code cache cleaning pass.
4056 _code_cache_task.barrier_wait(worker_id);
4057
4058 // Do the second code cache cleaning work, which realize on
4059 // the liveness information gathered during the first pass.
4060 _code_cache_task.work_second_pass(worker_id);
4061
4062 // Clean all klasses that were not unloaded.
4063 _klass_cleaning_task.work();
4064 }
4065 };
4066
4067
4068 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4069 bool process_strings,
4070 bool process_symbols,
4071 bool class_unloading_occurred) {
4072 uint n_workers = workers()->active_workers();
4073
4074 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4075 n_workers, class_unloading_occurred);
4076 workers()->run_task(&g1_unlink_task);
4077 }
4078
4079 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4080 bool process_strings, bool process_symbols) {
4081 {
4082 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4083 workers()->run_task(&g1_unlink_task);
4084 }
4085
4086 if (G1StringDedup::is_enabled()) {
4087 G1StringDedup::unlink(is_alive);
4088 }
4089 }
4090
4091 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4092 private:
4093 DirtyCardQueueSet* _queue;
4094 G1CollectedHeap* _g1h;
4095 public:
4096 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4097 _queue(queue), _g1h(g1h) { }
4098
4099 virtual void work(uint worker_id) {
4100 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4101 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4102
4103 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4104 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4105
4106 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4107 }
4108 };
4109
4110 void G1CollectedHeap::redirty_logged_cards() {
4111 double redirty_logged_cards_start = os::elapsedTime();
4112
4113 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4114 dirty_card_queue_set().reset_for_par_iteration();
4115 workers()->run_task(&redirty_task);
4116
4117 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4118 dcq.merge_bufferlists(&dirty_card_queue_set());
4119 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4120
4121 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4122 }
4123
4124 // Weak Reference Processing support
4125
4126 // An always "is_alive" closure that is used to preserve referents.
4127 // If the object is non-null then it's alive. Used in the preservation
4128 // of referent objects that are pointed to by reference objects
4129 // discovered by the CM ref processor.
4130 class G1AlwaysAliveClosure: public BoolObjectClosure {
4131 G1CollectedHeap* _g1;
4132 public:
4133 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4134 bool do_object_b(oop p) {
4135 if (p != NULL) {
4136 return true;
4137 }
4138 return false;
4139 }
4140 };
4141
4142 bool G1STWIsAliveClosure::do_object_b(oop p) {
4143 // An object is reachable if it is outside the collection set,
4144 // or is inside and copied.
4145 return !_g1->is_in_cset(p) || p->is_forwarded();
4146 }
4147
4148 // Non Copying Keep Alive closure
4149 class G1KeepAliveClosure: public OopClosure {
4150 G1CollectedHeap* _g1;
4151 public:
4152 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4153 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4154 void do_oop(oop* p) {
4155 oop obj = *p;
4156 assert(obj != NULL, "the caller should have filtered out NULL values");
4157
4158 const InCSetState cset_state = _g1->in_cset_state(obj);
4159 if (!cset_state.is_in_cset_or_humongous()) {
4160 return;
4161 }
4162 if (cset_state.is_in_cset()) {
4163 assert( obj->is_forwarded(), "invariant" );
4164 *p = obj->forwardee();
4165 } else {
4166 assert(!obj->is_forwarded(), "invariant" );
4167 assert(cset_state.is_humongous(),
4168 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4169 _g1->set_humongous_is_live(obj);
4170 }
4171 }
4172 };
4173
4174 // Copying Keep Alive closure - can be called from both
4175 // serial and parallel code as long as different worker
4176 // threads utilize different G1ParScanThreadState instances
4177 // and different queues.
4178
4179 class G1CopyingKeepAliveClosure: public OopClosure {
4180 G1CollectedHeap* _g1h;
4181 OopClosure* _copy_non_heap_obj_cl;
4182 G1ParScanThreadState* _par_scan_state;
4183
4184 public:
4185 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4186 OopClosure* non_heap_obj_cl,
4187 G1ParScanThreadState* pss):
4188 _g1h(g1h),
4189 _copy_non_heap_obj_cl(non_heap_obj_cl),
4190 _par_scan_state(pss)
4191 {}
4192
4193 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4194 virtual void do_oop( oop* p) { do_oop_work(p); }
4195
4196 template <class T> void do_oop_work(T* p) {
4197 oop obj = oopDesc::load_decode_heap_oop(p);
4198
4199 if (_g1h->is_in_cset_or_humongous(obj)) {
4200 // If the referent object has been forwarded (either copied
4201 // to a new location or to itself in the event of an
4202 // evacuation failure) then we need to update the reference
4203 // field and, if both reference and referent are in the G1
4204 // heap, update the RSet for the referent.
4205 //
4206 // If the referent has not been forwarded then we have to keep
4207 // it alive by policy. Therefore we have copy the referent.
4208 //
4209 // If the reference field is in the G1 heap then we can push
4210 // on the PSS queue. When the queue is drained (after each
4211 // phase of reference processing) the object and it's followers
4212 // will be copied, the reference field set to point to the
4213 // new location, and the RSet updated. Otherwise we need to
4214 // use the the non-heap or metadata closures directly to copy
4215 // the referent object and update the pointer, while avoiding
4216 // updating the RSet.
4217
4218 if (_g1h->is_in_g1_reserved(p)) {
4219 _par_scan_state->push_on_queue(p);
4220 } else {
4221 assert(!Metaspace::contains((const void*)p),
4222 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4223 _copy_non_heap_obj_cl->do_oop(p);
4224 }
4225 }
4226 }
4227 };
4228
4229 // Serial drain queue closure. Called as the 'complete_gc'
4230 // closure for each discovered list in some of the
4231 // reference processing phases.
4232
4233 class G1STWDrainQueueClosure: public VoidClosure {
4234 protected:
4235 G1CollectedHeap* _g1h;
4236 G1ParScanThreadState* _par_scan_state;
4237
4238 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4239
4240 public:
4241 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4242 _g1h(g1h),
4243 _par_scan_state(pss)
4244 { }
4245
4246 void do_void() {
4247 G1ParScanThreadState* const pss = par_scan_state();
4248 pss->trim_queue();
4249 }
4250 };
4251
4252 // Parallel Reference Processing closures
4253
4254 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4255 // processing during G1 evacuation pauses.
4256
4257 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4258 private:
4259 G1CollectedHeap* _g1h;
4260 G1ParScanThreadStateSet* _pss;
4261 RefToScanQueueSet* _queues;
4262 WorkGang* _workers;
4263 uint _active_workers;
4264
4265 public:
4266 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4267 G1ParScanThreadStateSet* per_thread_states,
4268 WorkGang* workers,
4269 RefToScanQueueSet *task_queues,
4270 uint n_workers) :
4271 _g1h(g1h),
4272 _pss(per_thread_states),
4273 _queues(task_queues),
4274 _workers(workers),
4275 _active_workers(n_workers)
4276 {
4277 assert(n_workers > 0, "shouldn't call this otherwise");
4278 }
4279
4280 // Executes the given task using concurrent marking worker threads.
4281 virtual void execute(ProcessTask& task);
4282 virtual void execute(EnqueueTask& task);
4283 };
4284
4285 // Gang task for possibly parallel reference processing
4286
4287 class G1STWRefProcTaskProxy: public AbstractGangTask {
4288 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4289 ProcessTask& _proc_task;
4290 G1CollectedHeap* _g1h;
4291 G1ParScanThreadStateSet* _pss;
4292 RefToScanQueueSet* _task_queues;
4293 ParallelTaskTerminator* _terminator;
4294
4295 public:
4296 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4297 G1CollectedHeap* g1h,
4298 G1ParScanThreadStateSet* per_thread_states,
4299 RefToScanQueueSet *task_queues,
4300 ParallelTaskTerminator* terminator) :
4301 AbstractGangTask("Process reference objects in parallel"),
4302 _proc_task(proc_task),
4303 _g1h(g1h),
4304 _pss(per_thread_states),
4305 _task_queues(task_queues),
4306 _terminator(terminator)
4307 {}
4308
4309 virtual void work(uint worker_id) {
4310 // The reference processing task executed by a single worker.
4311 ResourceMark rm;
4312 HandleMark hm;
4313
4314 G1STWIsAliveClosure is_alive(_g1h);
4315
4316 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4317 pss->set_ref_processor(NULL);
4318
4319 // Keep alive closure.
4320 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4321
4322 // Complete GC closure
4323 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4324
4325 // Call the reference processing task's work routine.
4326 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4327
4328 // Note we cannot assert that the refs array is empty here as not all
4329 // of the processing tasks (specifically phase2 - pp2_work) execute
4330 // the complete_gc closure (which ordinarily would drain the queue) so
4331 // the queue may not be empty.
4332 }
4333 };
4334
4335 // Driver routine for parallel reference processing.
4336 // Creates an instance of the ref processing gang
4337 // task and has the worker threads execute it.
4338 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4339 assert(_workers != NULL, "Need parallel worker threads.");
4340
4341 ParallelTaskTerminator terminator(_active_workers, _queues);
4342 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4343
4344 _workers->run_task(&proc_task_proxy);
4345 }
4346
4347 // Gang task for parallel reference enqueueing.
4348
4349 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4350 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4351 EnqueueTask& _enq_task;
4352
4353 public:
4354 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4355 AbstractGangTask("Enqueue reference objects in parallel"),
4356 _enq_task(enq_task)
4357 { }
4358
4359 virtual void work(uint worker_id) {
4360 _enq_task.work(worker_id);
4361 }
4362 };
4363
4364 // Driver routine for parallel reference enqueueing.
4365 // Creates an instance of the ref enqueueing gang
4366 // task and has the worker threads execute it.
4367
4368 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4369 assert(_workers != NULL, "Need parallel worker threads.");
4370
4371 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4372
4373 _workers->run_task(&enq_task_proxy);
4374 }
4375
4376 // End of weak reference support closures
4377
4378 // Abstract task used to preserve (i.e. copy) any referent objects
4379 // that are in the collection set and are pointed to by reference
4380 // objects discovered by the CM ref processor.
4381
4382 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4383 protected:
4384 G1CollectedHeap* _g1h;
4385 G1ParScanThreadStateSet* _pss;
4386 RefToScanQueueSet* _queues;
4387 ParallelTaskTerminator _terminator;
4388 uint _n_workers;
4389
4390 public:
4391 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4392 AbstractGangTask("ParPreserveCMReferents"),
4393 _g1h(g1h),
4394 _pss(per_thread_states),
4395 _queues(task_queues),
4396 _terminator(workers, _queues),
4397 _n_workers(workers)
4398 { }
4399
4400 void work(uint worker_id) {
4401 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4402
4403 ResourceMark rm;
4404 HandleMark hm;
4405
4406 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4407 pss->set_ref_processor(NULL);
4408 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4409
4410 // Is alive closure
4411 G1AlwaysAliveClosure always_alive(_g1h);
4412
4413 // Copying keep alive closure. Applied to referent objects that need
4414 // to be copied.
4415 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4416
4417 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4418
4419 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4420 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4421
4422 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4423 // So this must be true - but assert just in case someone decides to
4424 // change the worker ids.
4425 assert(worker_id < limit, "sanity");
4426 assert(!rp->discovery_is_atomic(), "check this code");
4427
4428 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4429 for (uint idx = worker_id; idx < limit; idx += stride) {
4430 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4431
4432 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4433 while (iter.has_next()) {
4434 // Since discovery is not atomic for the CM ref processor, we
4435 // can see some null referent objects.
4436 iter.load_ptrs(DEBUG_ONLY(true));
4437 oop ref = iter.obj();
4438
4439 // This will filter nulls.
4440 if (iter.is_referent_alive()) {
4441 iter.make_referent_alive();
4442 }
4443 iter.move_to_next();
4444 }
4445 }
4446
4447 // Drain the queue - which may cause stealing
4448 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4449 drain_queue.do_void();
4450 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4451 assert(pss->queue_is_empty(), "should be");
4452 }
4453 };
4454
4455 void G1CollectedHeap::process_weak_jni_handles() {
4456 double ref_proc_start = os::elapsedTime();
4457
4458 G1STWIsAliveClosure is_alive(this);
4459 G1KeepAliveClosure keep_alive(this);
4460 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4461
4462 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4463 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4464 }
4465
4466 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4467 double preserve_cm_referents_start = os::elapsedTime();
4468 // Any reference objects, in the collection set, that were 'discovered'
4469 // by the CM ref processor should have already been copied (either by
4470 // applying the external root copy closure to the discovered lists, or
4471 // by following an RSet entry).
4472 //
4473 // But some of the referents, that are in the collection set, that these
4474 // reference objects point to may not have been copied: the STW ref
4475 // processor would have seen that the reference object had already
4476 // been 'discovered' and would have skipped discovering the reference,
4477 // but would not have treated the reference object as a regular oop.
4478 // As a result the copy closure would not have been applied to the
4479 // referent object.
4480 //
4481 // We need to explicitly copy these referent objects - the references
4482 // will be processed at the end of remarking.
4483 //
4484 // We also need to do this copying before we process the reference
4485 // objects discovered by the STW ref processor in case one of these
4486 // referents points to another object which is also referenced by an
4487 // object discovered by the STW ref processor.
4488
4489 uint no_of_gc_workers = workers()->active_workers();
4490
4491 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4492 per_thread_states,
4493 no_of_gc_workers,
4494 _task_queues);
4495 workers()->run_task(&keep_cm_referents);
4496
4497 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4498 }
4499
4500 // Weak Reference processing during an evacuation pause (part 1).
4501 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4502 double ref_proc_start = os::elapsedTime();
4503
4504 ReferenceProcessor* rp = _ref_processor_stw;
4505 assert(rp->discovery_enabled(), "should have been enabled");
4506
4507 // Closure to test whether a referent is alive.
4508 G1STWIsAliveClosure is_alive(this);
4509
4510 // Even when parallel reference processing is enabled, the processing
4511 // of JNI refs is serial and performed serially by the current thread
4512 // rather than by a worker. The following PSS will be used for processing
4513 // JNI refs.
4514
4515 // Use only a single queue for this PSS.
4516 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4517 pss->set_ref_processor(NULL);
4518 assert(pss->queue_is_empty(), "pre-condition");
4519
4520 // Keep alive closure.
4521 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4522
4523 // Serial Complete GC closure
4524 G1STWDrainQueueClosure drain_queue(this, pss);
4525
4526 // Setup the soft refs policy...
4527 rp->setup_policy(false);
4528
4529 ReferenceProcessorStats stats;
4530 if (!rp->processing_is_mt()) {
4531 // Serial reference processing...
4532 stats = rp->process_discovered_references(&is_alive,
4533 &keep_alive,
4534 &drain_queue,
4535 NULL,
4536 _gc_timer_stw);
4537 } else {
4538 uint no_of_gc_workers = workers()->active_workers();
4539
4540 // Parallel reference processing
4541 assert(rp->num_q() == no_of_gc_workers, "sanity");
4542 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4543
4544 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4545 stats = rp->process_discovered_references(&is_alive,
4546 &keep_alive,
4547 &drain_queue,
4548 &par_task_executor,
4549 _gc_timer_stw);
4550 }
4551
4552 _gc_tracer_stw->report_gc_reference_stats(stats);
4553
4554 // We have completed copying any necessary live referent objects.
4555 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4556
4557 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4558 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4559 }
4560
4561 // Weak Reference processing during an evacuation pause (part 2).
4562 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4563 double ref_enq_start = os::elapsedTime();
4564
4565 ReferenceProcessor* rp = _ref_processor_stw;
4566 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4567
4568 // Now enqueue any remaining on the discovered lists on to
4569 // the pending list.
4570 if (!rp->processing_is_mt()) {
4571 // Serial reference processing...
4572 rp->enqueue_discovered_references();
4573 } else {
4574 // Parallel reference enqueueing
4575
4576 uint n_workers = workers()->active_workers();
4577
4578 assert(rp->num_q() == n_workers, "sanity");
4579 assert(n_workers <= rp->max_num_q(), "sanity");
4580
4581 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4582 rp->enqueue_discovered_references(&par_task_executor);
4583 }
4584
4585 rp->verify_no_references_recorded();
4586 assert(!rp->discovery_enabled(), "should have been disabled");
4587
4588 // FIXME
4589 // CM's reference processing also cleans up the string and symbol tables.
4590 // Should we do that here also? We could, but it is a serial operation
4591 // and could significantly increase the pause time.
4592
4593 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4594 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4595 }
4596
4597 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4598 double merge_pss_time_start = os::elapsedTime();
4599 per_thread_states->flush();
4600 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4601 }
4602
4603 void G1CollectedHeap::pre_evacuate_collection_set() {
4604 _expand_heap_after_alloc_failure = true;
4605 _evacuation_failed = false;
4606
4607 // Disable the hot card cache.
4608 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4609 hot_card_cache->reset_hot_cache_claimed_index();
4610 hot_card_cache->set_use_cache(false);
4611
4612 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4613 }
4614
4615 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4616 // Should G1EvacuationFailureALot be in effect for this GC?
4617 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4618
4619 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4620 double start_par_time_sec = os::elapsedTime();
4621 double end_par_time_sec;
4622
4623 {
4624 const uint n_workers = workers()->active_workers();
4625 G1RootProcessor root_processor(this, n_workers);
4626 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4627 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4628 if (collector_state()->during_initial_mark_pause()) {
4629 ClassLoaderDataGraph::clear_claimed_marks();
4630 }
4631
4632 print_termination_stats_hdr();
4633
4634 workers()->run_task(&g1_par_task);
4635 end_par_time_sec = os::elapsedTime();
4636
4637 // Closing the inner scope will execute the destructor
4638 // for the G1RootProcessor object. We record the current
4639 // elapsed time before closing the scope so that time
4640 // taken for the destructor is NOT included in the
4641 // reported parallel time.
4642 }
4643
4644 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4645
4646 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4647 phase_times->record_par_time(par_time_ms);
4648
4649 double code_root_fixup_time_ms =
4650 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4651 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4652 }
4653
4654 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4655 // Process any discovered reference objects - we have
4656 // to do this _before_ we retire the GC alloc regions
4657 // as we may have to copy some 'reachable' referent
4658 // objects (and their reachable sub-graphs) that were
4659 // not copied during the pause.
4660 if (g1_policy()->should_process_references()) {
4661 preserve_cm_referents(per_thread_states);
4662 process_discovered_references(per_thread_states);
4663 } else {
4664 ref_processor_stw()->verify_no_references_recorded();
4665 process_weak_jni_handles();
4666 }
4667
4668 if (G1StringDedup::is_enabled()) {
4669 double fixup_start = os::elapsedTime();
4670
4671 G1STWIsAliveClosure is_alive(this);
4672 G1KeepAliveClosure keep_alive(this);
4673 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4674
4675 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4676 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4677 }
4678
4679 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4680
4681 if (evacuation_failed()) {
4682 restore_after_evac_failure();
4683
4684 // Reset the G1EvacuationFailureALot counters and flags
4685 // Note: the values are reset only when an actual
4686 // evacuation failure occurs.
4687 NOT_PRODUCT(reset_evacuation_should_fail();)
4688 }
4689
4690 // Enqueue any remaining references remaining on the STW
4691 // reference processor's discovered lists. We need to do
4692 // this after the card table is cleaned (and verified) as
4693 // the act of enqueueing entries on to the pending list
4694 // will log these updates (and dirty their associated
4695 // cards). We need these updates logged to update any
4696 // RSets.
4697 if (g1_policy()->should_process_references()) {
4698 enqueue_discovered_references(per_thread_states);
4699 } else {
4700 g1_policy()->phase_times()->record_ref_enq_time(0);
4701 }
4702
4703 _allocator->release_gc_alloc_regions(evacuation_info);
4704
4705 merge_per_thread_state_info(per_thread_states);
4706
4707 record_obj_copy_mem_stats();
4708
4709 _survivor_evac_stats.adjust_desired_plab_sz();
4710 _old_evac_stats.adjust_desired_plab_sz();
4711
4712 // Reset and re-enable the hot card cache.
4713 // Note the counts for the cards in the regions in the
4714 // collection set are reset when the collection set is freed.
4715 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4716 hot_card_cache->reset_hot_cache();
4717 hot_card_cache->set_use_cache(true);
4718
4719 purge_code_root_memory();
4720
4721 redirty_logged_cards();
4722 #if defined(COMPILER2) || INCLUDE_JVMCI
4723 DerivedPointerTable::update_pointers();
4724 #endif
4725 }
4726
4727 void G1CollectedHeap::record_obj_copy_mem_stats() {
4728 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4729
4730 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4731 create_g1_evac_summary(&_old_evac_stats));
4732 }
4733
4734 void G1CollectedHeap::free_region(HeapRegion* hr,
4735 FreeRegionList* free_list,
4736 bool par,
4737 bool locked) {
4738 assert(!hr->is_free(), "the region should not be free");
4739 assert(!hr->is_empty(), "the region should not be empty");
4740 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4741 assert(free_list != NULL, "pre-condition");
4742
4743 if (G1VerifyBitmaps) {
4744 MemRegion mr(hr->bottom(), hr->end());
4745 concurrent_mark()->clearRangePrevBitmap(mr);
4746 }
4747
4748 // Clear the card counts for this region.
4749 // Note: we only need to do this if the region is not young
4750 // (since we don't refine cards in young regions).
4751 if (!hr->is_young()) {
4752 _cg1r->hot_card_cache()->reset_card_counts(hr);
4753 }
4754 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4755 free_list->add_ordered(hr);
4756 }
4757
4758 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4759 FreeRegionList* free_list,
4760 bool par) {
4761 assert(hr->is_humongous(), "this is only for humongous regions");
4762 assert(free_list != NULL, "pre-condition");
4763 hr->clear_humongous();
4764 free_region(hr, free_list, par);
4765 }
4766
4767 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4768 const uint humongous_regions_removed) {
4769 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4770 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4771 _old_set.bulk_remove(old_regions_removed);
4772 _humongous_set.bulk_remove(humongous_regions_removed);
4773 }
4774
4775 }
4776
4777 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4778 assert(list != NULL, "list can't be null");
4779 if (!list->is_empty()) {
4780 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4781 _hrm.insert_list_into_free_list(list);
4782 }
4783 }
4784
4785 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4786 decrease_used(bytes);
4787 }
4788
4789 class G1ParCleanupCTTask : public AbstractGangTask {
4790 G1SATBCardTableModRefBS* _ct_bs;
4791 G1CollectedHeap* _g1h;
4792 HeapRegion* volatile _su_head;
4793 public:
4794 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4795 G1CollectedHeap* g1h) :
4796 AbstractGangTask("G1 Par Cleanup CT Task"),
4797 _ct_bs(ct_bs), _g1h(g1h) { }
4798
4799 void work(uint worker_id) {
4800 HeapRegion* r;
4801 while (r = _g1h->pop_dirty_cards_region()) {
4802 clear_cards(r);
4803 }
4804 }
4805
4806 void clear_cards(HeapRegion* r) {
4807 // Cards of the survivors should have already been dirtied.
4808 if (!r->is_survivor()) {
4809 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4810 }
4811 }
4812 };
4813
4814 class G1ParScrubRemSetTask: public AbstractGangTask {
4815 protected:
4816 G1RemSet* _g1rs;
4817 BitMap* _region_bm;
4818 BitMap* _card_bm;
4819 HeapRegionClaimer _hrclaimer;
4820
4821 public:
4822 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4823 AbstractGangTask("G1 ScrubRS"),
4824 _g1rs(g1_rs),
4825 _region_bm(region_bm),
4826 _card_bm(card_bm),
4827 _hrclaimer(num_workers) {
4828 }
4829
4830 void work(uint worker_id) {
4831 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4832 }
4833 };
4834
4835 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4836 uint num_workers = workers()->active_workers();
4837 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4838 workers()->run_task(&g1_par_scrub_rs_task);
4839 }
4840
4841 void G1CollectedHeap::cleanUpCardTable() {
4842 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4843 double start = os::elapsedTime();
4844
4845 {
4846 // Iterate over the dirty cards region list.
4847 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4848
4849 workers()->run_task(&cleanup_task);
4850 #ifndef PRODUCT
4851 _verifier->verify_card_table_cleanup();
4852 #endif
4853 }
4854
4855 double elapsed = os::elapsedTime() - start;
4856 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4857 }
4858
4859 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4860 size_t pre_used = 0;
4861 FreeRegionList local_free_list("Local List for CSet Freeing");
4862
4863 double young_time_ms = 0.0;
4864 double non_young_time_ms = 0.0;
4865
4866 // Since the collection set is a superset of the the young list,
4867 // all we need to do to clear the young list is clear its
4868 // head and length, and unlink any young regions in the code below
4869 _young_list->clear();
4870
4871 G1CollectorPolicy* policy = g1_policy();
4872
4873 double start_sec = os::elapsedTime();
4874 bool non_young = true;
4875
4876 HeapRegion* cur = cs_head;
4877 int age_bound = -1;
4878 size_t rs_lengths = 0;
4879
4880 while (cur != NULL) {
4881 assert(!is_on_master_free_list(cur), "sanity");
4882 if (non_young) {
4883 if (cur->is_young()) {
4884 double end_sec = os::elapsedTime();
4885 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4886 non_young_time_ms += elapsed_ms;
4887
4888 start_sec = os::elapsedTime();
4889 non_young = false;
4890 }
4891 } else {
4892 if (!cur->is_young()) {
4893 double end_sec = os::elapsedTime();
4894 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4895 young_time_ms += elapsed_ms;
4896
4897 start_sec = os::elapsedTime();
4898 non_young = true;
4899 }
4900 }
4901
4902 rs_lengths += cur->rem_set()->occupied_locked();
4903
4904 HeapRegion* next = cur->next_in_collection_set();
4905 assert(cur->in_collection_set(), "bad CS");
4906 cur->set_next_in_collection_set(NULL);
4907 clear_in_cset(cur);
4908
4909 if (cur->is_young()) {
4910 int index = cur->young_index_in_cset();
4911 assert(index != -1, "invariant");
4912 assert((uint) index < policy->young_cset_region_length(), "invariant");
4913 size_t words_survived = surviving_young_words[index];
4914 cur->record_surv_words_in_group(words_survived);
4915
4916 // At this point the we have 'popped' cur from the collection set
4917 // (linked via next_in_collection_set()) but it is still in the
4918 // young list (linked via next_young_region()). Clear the
4919 // _next_young_region field.
4920 cur->set_next_young_region(NULL);
4921 } else {
4922 int index = cur->young_index_in_cset();
4923 assert(index == -1, "invariant");
4924 }
4925
4926 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4927 (!cur->is_young() && cur->young_index_in_cset() == -1),
4928 "invariant" );
4929
4930 if (!cur->evacuation_failed()) {
4931 MemRegion used_mr = cur->used_region();
4932
4933 // And the region is empty.
4934 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4935 pre_used += cur->used();
4936 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4937 } else {
4938 cur->uninstall_surv_rate_group();
4939 if (cur->is_young()) {
4940 cur->set_young_index_in_cset(-1);
4941 }
4942 cur->set_evacuation_failed(false);
4943 // When moving a young gen region to old gen, we "allocate" that whole region
4944 // there. This is in addition to any already evacuated objects. Notify the
4945 // policy about that.
4946 // Old gen regions do not cause an additional allocation: both the objects
4947 // still in the region and the ones already moved are accounted for elsewhere.
4948 if (cur->is_young()) {
4949 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4950 }
4951 // The region is now considered to be old.
4952 cur->set_old();
4953 // Do some allocation statistics accounting. Regions that failed evacuation
4954 // are always made old, so there is no need to update anything in the young
4955 // gen statistics, but we need to update old gen statistics.
4956 size_t used_words = cur->marked_bytes() / HeapWordSize;
4957 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4958 _old_set.add(cur);
4959 evacuation_info.increment_collectionset_used_after(cur->used());
4960 }
4961 cur = next;
4962 }
4963
4964 evacuation_info.set_regions_freed(local_free_list.length());
4965 policy->record_max_rs_lengths(rs_lengths);
4966 policy->cset_regions_freed();
4967
4968 double end_sec = os::elapsedTime();
4969 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4970
4971 if (non_young) {
4972 non_young_time_ms += elapsed_ms;
4973 } else {
4974 young_time_ms += elapsed_ms;
4975 }
4976
4977 prepend_to_freelist(&local_free_list);
4978 decrement_summary_bytes(pre_used);
4979 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4980 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4981 }
4982
4983 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4984 private:
4985 FreeRegionList* _free_region_list;
4986 HeapRegionSet* _proxy_set;
4987 uint _humongous_regions_removed;
4988 size_t _freed_bytes;
4989 public:
4990
4991 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4992 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4993 }
4994
4995 virtual bool doHeapRegion(HeapRegion* r) {
4996 if (!r->is_starts_humongous()) {
4997 return false;
4998 }
4999
5000 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5001
5002 oop obj = (oop)r->bottom();
5003 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5004
5005 // The following checks whether the humongous object is live are sufficient.
5006 // The main additional check (in addition to having a reference from the roots
5007 // or the young gen) is whether the humongous object has a remembered set entry.
5008 //
5009 // A humongous object cannot be live if there is no remembered set for it
5010 // because:
5011 // - there can be no references from within humongous starts regions referencing
5012 // the object because we never allocate other objects into them.
5013 // (I.e. there are no intra-region references that may be missed by the
5014 // remembered set)
5015 // - as soon there is a remembered set entry to the humongous starts region
5016 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5017 // until the end of a concurrent mark.
5018 //
5019 // It is not required to check whether the object has been found dead by marking
5020 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5021 // all objects allocated during that time are considered live.
5022 // SATB marking is even more conservative than the remembered set.
5023 // So if at this point in the collection there is no remembered set entry,
5024 // nobody has a reference to it.
5025 // At the start of collection we flush all refinement logs, and remembered sets
5026 // are completely up-to-date wrt to references to the humongous object.
5027 //
5028 // Other implementation considerations:
5029 // - never consider object arrays at this time because they would pose
5030 // considerable effort for cleaning up the the remembered sets. This is
5031 // required because stale remembered sets might reference locations that
5032 // are currently allocated into.
5033 uint region_idx = r->hrm_index();
5034 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5035 !r->rem_set()->is_empty()) {
5036 log_debug(gc, humongous)("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",
5037 region_idx,
5038 (size_t)obj->size() * HeapWordSize,
5039 p2i(r->bottom()),
5040 r->rem_set()->occupied(),
5041 r->rem_set()->strong_code_roots_list_length(),
5042 next_bitmap->isMarked(r->bottom()),
5043 g1h->is_humongous_reclaim_candidate(region_idx),
5044 obj->is_typeArray()
5045 );
5046 return false;
5047 }
5048
5049 guarantee(obj->is_typeArray(),
5050 "Only eagerly reclaiming type arrays is supported, but the object "
5051 PTR_FORMAT " is not.", p2i(r->bottom()));
5052
5053 log_debug(gc, humongous)("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",
5054 region_idx,
5055 (size_t)obj->size() * HeapWordSize,
5056 p2i(r->bottom()),
5057 r->rem_set()->occupied(),
5058 r->rem_set()->strong_code_roots_list_length(),
5059 next_bitmap->isMarked(r->bottom()),
5060 g1h->is_humongous_reclaim_candidate(region_idx),
5061 obj->is_typeArray()
5062 );
5063
5064 // Need to clear mark bit of the humongous object if already set.
5065 if (next_bitmap->isMarked(r->bottom())) {
5066 next_bitmap->clear(r->bottom());
5067 }
5068 do {
5069 HeapRegion* next = g1h->next_region_in_humongous(r);
5070 _freed_bytes += r->used();
5071 r->set_containing_set(NULL);
5072 _humongous_regions_removed++;
5073 g1h->free_humongous_region(r, _free_region_list, false);
5074 r = next;
5075 } while (r != NULL);
5076
5077 return false;
5078 }
5079
5080 uint humongous_free_count() {
5081 return _humongous_regions_removed;
5082 }
5083
5084 size_t bytes_freed() const {
5085 return _freed_bytes;
5086 }
5087 };
5088
5089 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5090 assert_at_safepoint(true);
5091
5092 if (!G1EagerReclaimHumongousObjects ||
5093 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5094 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5095 return;
5096 }
5097
5098 double start_time = os::elapsedTime();
5099
5100 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5101
5102 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5103 heap_region_iterate(&cl);
5104
5105 remove_from_old_sets(0, cl.humongous_free_count());
5106
5107 G1HRPrinter* hrp = hr_printer();
5108 if (hrp->is_active()) {
5109 FreeRegionListIterator iter(&local_cleanup_list);
5110 while (iter.more_available()) {
5111 HeapRegion* hr = iter.get_next();
5112 hrp->cleanup(hr);
5113 }
5114 }
5115
5116 prepend_to_freelist(&local_cleanup_list);
5117 decrement_summary_bytes(cl.bytes_freed());
5118
5119 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5120 cl.humongous_free_count());
5121 }
5122
5123 // This routine is similar to the above but does not record
5124 // any policy statistics or update free lists; we are abandoning
5125 // the current incremental collection set in preparation of a
5126 // full collection. After the full GC we will start to build up
5127 // the incremental collection set again.
5128 // This is only called when we're doing a full collection
5129 // and is immediately followed by the tearing down of the young list.
5130
5131 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5132 HeapRegion* cur = cs_head;
5133
5134 while (cur != NULL) {
5135 HeapRegion* next = cur->next_in_collection_set();
5136 assert(cur->in_collection_set(), "bad CS");
5137 cur->set_next_in_collection_set(NULL);
5138 clear_in_cset(cur);
5139 cur->set_young_index_in_cset(-1);
5140 cur = next;
5141 }
5142 }
5143
5144 void G1CollectedHeap::set_free_regions_coming() {
5145 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5146
5147 assert(!free_regions_coming(), "pre-condition");
5148 _free_regions_coming = true;
5149 }
5150
5151 void G1CollectedHeap::reset_free_regions_coming() {
5152 assert(free_regions_coming(), "pre-condition");
5153
5154 {
5155 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5156 _free_regions_coming = false;
5157 SecondaryFreeList_lock->notify_all();
5158 }
5159
5160 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5161 }
5162
5163 void G1CollectedHeap::wait_while_free_regions_coming() {
5164 // Most of the time we won't have to wait, so let's do a quick test
5165 // first before we take the lock.
5166 if (!free_regions_coming()) {
5167 return;
5168 }
5169
5170 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5171
5172 {
5173 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5174 while (free_regions_coming()) {
5175 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5176 }
5177 }
5178
5179 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5180 }
5181
5182 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5183 return _allocator->is_retained_old_region(hr);
5184 }
5185
5186 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5187 _young_list->push_region(hr);
5188 }
5189
5190 class NoYoungRegionsClosure: public HeapRegionClosure {
5191 private:
5192 bool _success;
5193 public:
5194 NoYoungRegionsClosure() : _success(true) { }
5195 bool doHeapRegion(HeapRegion* r) {
5196 if (r->is_young()) {
5197 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5198 p2i(r->bottom()), p2i(r->end()));
5199 _success = false;
5200 }
5201 return false;
5202 }
5203 bool success() { return _success; }
5204 };
5205
5206 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5207 bool ret = _young_list->check_list_empty(check_sample);
5208
5209 if (check_heap) {
5210 NoYoungRegionsClosure closure;
5211 heap_region_iterate(&closure);
5212 ret = ret && closure.success();
5213 }
5214
5215 return ret;
5216 }
5217
5218 class TearDownRegionSetsClosure : public HeapRegionClosure {
5219 private:
5220 HeapRegionSet *_old_set;
5221
5222 public:
5223 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5224
5225 bool doHeapRegion(HeapRegion* r) {
5226 if (r->is_old()) {
5227 _old_set->remove(r);
5228 } else {
5229 // We ignore free regions, we'll empty the free list afterwards.
5230 // We ignore young regions, we'll empty the young list afterwards.
5231 // We ignore humongous regions, we're not tearing down the
5232 // humongous regions set.
5233 assert(r->is_free() || r->is_young() || r->is_humongous(),
5234 "it cannot be another type");
5235 }
5236 return false;
5237 }
5238
5239 ~TearDownRegionSetsClosure() {
5240 assert(_old_set->is_empty(), "post-condition");
5241 }
5242 };
5243
5244 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5245 assert_at_safepoint(true /* should_be_vm_thread */);
5246
5247 if (!free_list_only) {
5248 TearDownRegionSetsClosure cl(&_old_set);
5249 heap_region_iterate(&cl);
5250
5251 // Note that emptying the _young_list is postponed and instead done as
5252 // the first step when rebuilding the regions sets again. The reason for
5253 // this is that during a full GC string deduplication needs to know if
5254 // a collected region was young or old when the full GC was initiated.
5255 }
5256 _hrm.remove_all_free_regions();
5257 }
5258
5259 void G1CollectedHeap::increase_used(size_t bytes) {
5260 _summary_bytes_used += bytes;
5261 }
5262
5263 void G1CollectedHeap::decrease_used(size_t bytes) {
5264 assert(_summary_bytes_used >= bytes,
5265 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5266 _summary_bytes_used, bytes);
5267 _summary_bytes_used -= bytes;
5268 }
5269
5270 void G1CollectedHeap::set_used(size_t bytes) {
5271 _summary_bytes_used = bytes;
5272 }
5273
5274 class RebuildRegionSetsClosure : public HeapRegionClosure {
5275 private:
5276 bool _free_list_only;
5277 HeapRegionSet* _old_set;
5278 HeapRegionManager* _hrm;
5279 size_t _total_used;
5280
5281 public:
5282 RebuildRegionSetsClosure(bool free_list_only,
5283 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5284 _free_list_only(free_list_only),
5285 _old_set(old_set), _hrm(hrm), _total_used(0) {
5286 assert(_hrm->num_free_regions() == 0, "pre-condition");
5287 if (!free_list_only) {
5288 assert(_old_set->is_empty(), "pre-condition");
5289 }
5290 }
5291
5292 bool doHeapRegion(HeapRegion* r) {
5293 if (r->is_empty()) {
5294 // Add free regions to the free list
5295 r->set_free();
5296 r->set_allocation_context(AllocationContext::system());
5297 _hrm->insert_into_free_list(r);
5298 } else if (!_free_list_only) {
5299 assert(!r->is_young(), "we should not come across young regions");
5300
5301 if (r->is_humongous()) {
5302 // We ignore humongous regions. We left the humongous set unchanged.
5303 } else {
5304 // Objects that were compacted would have ended up on regions
5305 // that were previously old or free. Archive regions (which are
5306 // old) will not have been touched.
5307 assert(r->is_free() || r->is_old(), "invariant");
5308 // We now consider them old, so register as such. Leave
5309 // archive regions set that way, however, while still adding
5310 // them to the old set.
5311 if (!r->is_archive()) {
5312 r->set_old();
5313 }
5314 _old_set->add(r);
5315 }
5316 _total_used += r->used();
5317 }
5318
5319 return false;
5320 }
5321
5322 size_t total_used() {
5323 return _total_used;
5324 }
5325 };
5326
5327 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5328 assert_at_safepoint(true /* should_be_vm_thread */);
5329
5330 if (!free_list_only) {
5331 _young_list->empty_list();
5332 }
5333
5334 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5335 heap_region_iterate(&cl);
5336
5337 if (!free_list_only) {
5338 set_used(cl.total_used());
5339 if (_archive_allocator != NULL) {
5340 _archive_allocator->clear_used();
5341 }
5342 }
5343 assert(used_unlocked() == recalculate_used(),
5344 "inconsistent used_unlocked(), "
5345 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5346 used_unlocked(), recalculate_used());
5347 }
5348
5349 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5350 _refine_cte_cl->set_concurrent(concurrent);
5351 }
5352
5353 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5354 HeapRegion* hr = heap_region_containing(p);
5355 return hr->is_in(p);
5356 }
5357
5358 // Methods for the mutator alloc region
5359
5360 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5361 bool force) {
5362 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5363 assert(!force || g1_policy()->can_expand_young_list(),
5364 "if force is true we should be able to expand the young list");
5365 bool young_list_full = g1_policy()->is_young_list_full();
5366 if (force || !young_list_full) {
5367 HeapRegion* new_alloc_region = new_region(word_size,
5368 false /* is_old */,
5369 false /* do_expand */);
5370 if (new_alloc_region != NULL) {
5371 set_region_short_lived_locked(new_alloc_region);
5372 _hr_printer.alloc(new_alloc_region, young_list_full);
5373 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5374 return new_alloc_region;
5375 }
5376 }
5377 return NULL;
5378 }
5379
5380 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5381 size_t allocated_bytes) {
5382 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5383 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5384
5385 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5386 increase_used(allocated_bytes);
5387 _hr_printer.retire(alloc_region);
5388 // We update the eden sizes here, when the region is retired,
5389 // instead of when it's allocated, since this is the point that its
5390 // used space has been recored in _summary_bytes_used.
5391 g1mm()->update_eden_size();
5392 }
5393
5394 // Methods for the GC alloc regions
5395
5396 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5397 uint count,
5398 InCSetState dest) {
5399 assert(FreeList_lock->owned_by_self(), "pre-condition");
5400
5401 if (count < g1_policy()->max_regions(dest)) {
5402 const bool is_survivor = (dest.is_young());
5403 HeapRegion* new_alloc_region = new_region(word_size,
5404 !is_survivor,
5405 true /* do_expand */);
5406 if (new_alloc_region != NULL) {
5407 // We really only need to do this for old regions given that we
5408 // should never scan survivors. But it doesn't hurt to do it
5409 // for survivors too.
5410 new_alloc_region->record_timestamp();
5411 if (is_survivor) {
5412 new_alloc_region->set_survivor();
5413 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5414 } else {
5415 new_alloc_region->set_old();
5416 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5417 }
5418 _hr_printer.alloc(new_alloc_region);
5419 bool during_im = collector_state()->during_initial_mark_pause();
5420 new_alloc_region->note_start_of_copying(during_im);
5421 return new_alloc_region;
5422 }
5423 }
5424 return NULL;
5425 }
5426
5427 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5428 size_t allocated_bytes,
5429 InCSetState dest) {
5430 bool during_im = collector_state()->during_initial_mark_pause();
5431 alloc_region->note_end_of_copying(during_im);
5432 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5433 if (dest.is_young()) {
5434 young_list()->add_survivor_region(alloc_region);
5435 } else {
5436 _old_set.add(alloc_region);
5437 }
5438 _hr_printer.retire(alloc_region);
5439 }
5440
5441 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5442 bool expanded = false;
5443 uint index = _hrm.find_highest_free(&expanded);
5444
5445 if (index != G1_NO_HRM_INDEX) {
5446 if (expanded) {
5447 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5448 HeapRegion::GrainWords * HeapWordSize);
5449 }
5450 _hrm.allocate_free_regions_starting_at(index, 1);
5451 return region_at(index);
5452 }
5453 return NULL;
5454 }
5455
5456 // Optimized nmethod scanning
5457
5458 class RegisterNMethodOopClosure: public OopClosure {
5459 G1CollectedHeap* _g1h;
5460 nmethod* _nm;
5461
5462 template <class T> void do_oop_work(T* p) {
5463 T heap_oop = oopDesc::load_heap_oop(p);
5464 if (!oopDesc::is_null(heap_oop)) {
5465 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5466 HeapRegion* hr = _g1h->heap_region_containing(obj);
5467 assert(!hr->is_continues_humongous(),
5468 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5469 " starting at " HR_FORMAT,
5470 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5471
5472 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5473 hr->add_strong_code_root_locked(_nm);
5474 }
5475 }
5476
5477 public:
5478 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5479 _g1h(g1h), _nm(nm) {}
5480
5481 void do_oop(oop* p) { do_oop_work(p); }
5482 void do_oop(narrowOop* p) { do_oop_work(p); }
5483 };
5484
5485 class UnregisterNMethodOopClosure: public OopClosure {
5486 G1CollectedHeap* _g1h;
5487 nmethod* _nm;
5488
5489 template <class T> void do_oop_work(T* p) {
5490 T heap_oop = oopDesc::load_heap_oop(p);
5491 if (!oopDesc::is_null(heap_oop)) {
5492 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5493 HeapRegion* hr = _g1h->heap_region_containing(obj);
5494 assert(!hr->is_continues_humongous(),
5495 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5496 " starting at " HR_FORMAT,
5497 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5498
5499 hr->remove_strong_code_root(_nm);
5500 }
5501 }
5502
5503 public:
5504 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5505 _g1h(g1h), _nm(nm) {}
5506
5507 void do_oop(oop* p) { do_oop_work(p); }
5508 void do_oop(narrowOop* p) { do_oop_work(p); }
5509 };
5510
5511 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5512 CollectedHeap::register_nmethod(nm);
5513
5514 guarantee(nm != NULL, "sanity");
5515 RegisterNMethodOopClosure reg_cl(this, nm);
5516 nm->oops_do(®_cl);
5517 }
5518
5519 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5520 CollectedHeap::unregister_nmethod(nm);
5521
5522 guarantee(nm != NULL, "sanity");
5523 UnregisterNMethodOopClosure reg_cl(this, nm);
5524 nm->oops_do(®_cl, true);
5525 }
5526
5527 void G1CollectedHeap::purge_code_root_memory() {
5528 double purge_start = os::elapsedTime();
5529 G1CodeRootSet::purge();
5530 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5531 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5532 }
5533
5534 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5535 G1CollectedHeap* _g1h;
5536
5537 public:
5538 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5539 _g1h(g1h) {}
5540
5541 void do_code_blob(CodeBlob* cb) {
5542 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5543 if (nm == NULL) {
5544 return;
5545 }
5546
5547 if (ScavengeRootsInCode) {
5548 _g1h->register_nmethod(nm);
5549 }
5550 }
5551 };
5552
5553 void G1CollectedHeap::rebuild_strong_code_roots() {
5554 RebuildStrongCodeRootClosure blob_cl(this);
5555 CodeCache::blobs_do(&blob_cl);
5556 }