1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "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/g1MarkSweep.hpp"
42 #include "gc/g1/g1OopClosures.inline.hpp"
43 #include "gc/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc/g1/g1RemSet.inline.hpp"
46 #include "gc/g1/g1RootClosures.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcId.hpp"
57 #include "gc/shared/gcLocker.inline.hpp"
58 #include "gc/shared/gcTimer.hpp"
59 #include "gc/shared/gcTrace.hpp"
60 #include "gc/shared/gcTraceTime.inline.hpp"
61 #include "gc/shared/generationSpec.hpp"
62 #include "gc/shared/isGCActiveMark.hpp"
63 #include "gc/shared/referenceProcessor.hpp"
64 #include "gc/shared/taskqueue.inline.hpp"
65 #include "logging/log.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_dirtied;
116 G1CollectedHeap* _g1h;
117 G1SATBCardTableLoggingModRefBS* _g1_bs;
118
119 HeapRegion* region_for_card(jbyte* card_ptr) const {
120 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
121 }
122
123 bool will_become_free(HeapRegion* hr) const {
124 // A region will be freed by free_collection_set if the region is in the
125 // collection set and has not had an evacuation failure.
126 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
127 }
128
129 public:
130 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
131 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
132
133 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
134 HeapRegion* hr = region_for_card(card_ptr);
135
136 // Should only dirty cards in regions that won't be freed.
137 if (!will_become_free(hr)) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_dirtied++;
140 }
141
142 return true;
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
160 {
161 // Claim the right to put the region on the dirty cards region list
162 // by installing a self pointer.
163 HeapRegion* next = hr->get_next_dirty_cards_region();
164 if (next == NULL) {
165 HeapRegion* res = (HeapRegion*)
166 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
167 NULL);
168 if (res == NULL) {
169 HeapRegion* head;
170 do {
171 // Put the region to the dirty cards region list.
172 head = _dirty_cards_region_list;
173 next = (HeapRegion*)
174 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
175 if (next == head) {
176 assert(hr->get_next_dirty_cards_region() == hr,
177 "hr->get_next_dirty_cards_region() != hr");
178 if (next == NULL) {
179 // The last region in the list points to itself.
180 hr->set_next_dirty_cards_region(hr);
181 } else {
182 hr->set_next_dirty_cards_region(next);
183 }
184 }
185 } while (next != head);
186 }
187 }
188 }
189
190 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
191 {
192 HeapRegion* head;
193 HeapRegion* hr;
194 do {
195 head = _dirty_cards_region_list;
196 if (head == NULL) {
197 return NULL;
198 }
199 HeapRegion* new_head = head->get_next_dirty_cards_region();
200 if (head == new_head) {
201 // The last region.
202 new_head = NULL;
203 }
204 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
205 head);
206 } while (hr != head);
207 assert(hr != NULL, "invariant");
208 hr->set_next_dirty_cards_region(NULL);
209 return hr;
210 }
211
212 // Returns true if the reference points to an object that
213 // can move in an incremental collection.
214 bool G1CollectedHeap::is_scavengable(const void* p) {
215 HeapRegion* hr = heap_region_containing(p);
216 return !hr->is_pinned();
217 }
218
219 // Private methods.
220
221 HeapRegion*
222 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
223 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
224 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
225 if (!_secondary_free_list.is_empty()) {
226 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
227 "secondary_free_list has %u entries",
228 _secondary_free_list.length());
229 // It looks as if there are free regions available on the
230 // secondary_free_list. Let's move them to the free_list and try
231 // again to allocate from it.
232 append_secondary_free_list();
233
234 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
235 "empty we should have moved at least one entry to the free_list");
236 HeapRegion* res = _hrm.allocate_free_region(is_old);
237 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
238 "allocated " HR_FORMAT " from secondary_free_list",
239 HR_FORMAT_PARAMS(res));
240 return res;
241 }
242
243 // Wait here until we get notified either when (a) there are no
244 // more free regions coming or (b) some regions have been moved on
245 // the secondary_free_list.
246 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
247 }
248
249 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
250 "could not allocate from secondary_free_list");
251 return NULL;
252 }
253
254 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
255 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
256 "the only time we use this to allocate a humongous region is "
257 "when we are allocating a single humongous region");
258
259 HeapRegion* res;
260 if (G1StressConcRegionFreeing) {
261 if (!_secondary_free_list.is_empty()) {
262 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
263 "forced to look at the secondary_free_list");
264 res = new_region_try_secondary_free_list(is_old);
265 if (res != NULL) {
266 return res;
267 }
268 }
269 }
270
271 res = _hrm.allocate_free_region(is_old);
272
273 if (res == NULL) {
274 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
275 "res == NULL, trying the secondary_free_list");
276 res = new_region_try_secondary_free_list(is_old);
277 }
278 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
279 // Currently, only attempts to allocate GC alloc regions set
280 // do_expand to true. So, we should only reach here during a
281 // safepoint. If this assumption changes we might have to
282 // reconsider the use of _expand_heap_after_alloc_failure.
283 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
284
285 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
286 word_size * HeapWordSize);
287
288 if (expand(word_size * HeapWordSize)) {
289 // Given that expand() succeeded in expanding the heap, and we
290 // always expand the heap by an amount aligned to the heap
291 // region size, the free list should in theory not be empty.
292 // In either case allocate_free_region() will check for NULL.
293 res = _hrm.allocate_free_region(is_old);
294 } else {
295 _expand_heap_after_alloc_failure = false;
296 }
297 }
298 return res;
299 }
300
301 HeapWord*
302 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
303 uint num_regions,
304 size_t word_size,
305 AllocationContext_t context) {
306 assert(first != G1_NO_HRM_INDEX, "pre-condition");
307 assert(is_humongous(word_size), "word_size should be humongous");
308 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
309
310 // Index of last region in the series.
311 uint last = first + num_regions - 1;
312
313 // We need to initialize the region(s) we just discovered. This is
314 // a bit tricky given that it can happen concurrently with
315 // refinement threads refining cards on these regions and
316 // potentially wanting to refine the BOT as they are scanning
317 // those cards (this can happen shortly after a cleanup; see CR
318 // 6991377). So we have to set up the region(s) carefully and in
319 // a specific order.
320
321 // The word size sum of all the regions we will allocate.
322 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
323 assert(word_size <= word_size_sum, "sanity");
324
325 // This will be the "starts humongous" region.
326 HeapRegion* first_hr = region_at(first);
327 // The header of the new object will be placed at the bottom of
328 // the first region.
329 HeapWord* new_obj = first_hr->bottom();
330 // This will be the new top of the new object.
331 HeapWord* obj_top = new_obj + word_size;
332
333 // First, we need to zero the header of the space that we will be
334 // allocating. When we update top further down, some refinement
335 // threads might try to scan the region. By zeroing the header we
336 // ensure that any thread that will try to scan the region will
337 // come across the zero klass word and bail out.
338 //
339 // NOTE: It would not have been correct to have used
340 // CollectedHeap::fill_with_object() and make the space look like
341 // an int array. The thread that is doing the allocation will
342 // later update the object header to a potentially different array
343 // type and, for a very short period of time, the klass and length
344 // fields will be inconsistent. This could cause a refinement
345 // thread to calculate the object size incorrectly.
346 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
347
348 // How many words we use for filler objects.
349 size_t word_fill_size = word_size_sum - word_size;
350
351 // How many words memory we "waste" which cannot hold a filler object.
352 size_t words_not_fillable = 0;
353
354 if (word_fill_size >= min_fill_size()) {
355 fill_with_objects(obj_top, word_fill_size);
356 } else if (word_fill_size > 0) {
357 // We have space to fill, but we cannot fit an object there.
358 words_not_fillable = word_fill_size;
359 word_fill_size = 0;
360 }
361
362 // We will set up the first region as "starts humongous". This
363 // will also update the BOT covering all the regions to reflect
364 // that there is a single object that starts at the bottom of the
365 // first region.
366 first_hr->set_starts_humongous(obj_top, word_fill_size);
367 first_hr->set_allocation_context(context);
368 // Then, if there are any, we will set up the "continues
369 // humongous" regions.
370 HeapRegion* hr = NULL;
371 for (uint i = first + 1; i <= last; ++i) {
372 hr = region_at(i);
373 hr->set_continues_humongous(first_hr);
374 hr->set_allocation_context(context);
375 }
376
377 // Up to this point no concurrent thread would have been able to
378 // do any scanning on any region in this series. All the top
379 // fields still point to bottom, so the intersection between
380 // [bottom,top] and [card_start,card_end] will be empty. Before we
381 // update the top fields, we'll do a storestore to make sure that
382 // no thread sees the update to top before the zeroing of the
383 // object header and the BOT initialization.
384 OrderAccess::storestore();
385
386 // Now, we will update the top fields of the "continues humongous"
387 // regions except the last one.
388 for (uint i = first; i < last; ++i) {
389 hr = region_at(i);
390 hr->set_top(hr->end());
391 }
392
393 hr = region_at(last);
394 // If we cannot fit a filler object, we must set top to the end
395 // of the humongous object, otherwise we cannot iterate the heap
396 // and the BOT will not be complete.
397 hr->set_top(hr->end() - words_not_fillable);
398
399 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
400 "obj_top should be in last region");
401
402 check_bitmaps("Humongous Region Allocation", first_hr);
403
404 assert(words_not_fillable == 0 ||
405 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
406 "Miscalculation in humongous allocation");
407
408 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
409
410 for (uint i = first; i <= last; ++i) {
411 hr = region_at(i);
412 _humongous_set.add(hr);
413 _hr_printer.alloc(hr);
414 }
415
416 return new_obj;
417 }
418
419 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
420 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
421 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
422 }
423
424 // If could fit into free regions w/o expansion, try.
425 // Otherwise, if can expand, do so.
426 // Otherwise, if using ex regions might help, try with ex given back.
427 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
428 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
429
430 verify_region_sets_optional();
431
432 uint first = G1_NO_HRM_INDEX;
433 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
434
435 if (obj_regions == 1) {
436 // Only one region to allocate, try to use a fast path by directly allocating
437 // from the free lists. Do not try to expand here, we will potentially do that
438 // later.
439 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
440 if (hr != NULL) {
441 first = hr->hrm_index();
442 }
443 } else {
444 // We can't allocate humongous regions spanning more than one region while
445 // cleanupComplete() is running, since some of the regions we find to be
446 // empty might not yet be added to the free list. It is not straightforward
447 // to know in which list they are on so that we can remove them. We only
448 // need to do this if we need to allocate more than one region to satisfy the
449 // current humongous allocation request. If we are only allocating one region
450 // we use the one-region region allocation code (see above), that already
451 // potentially waits for regions from the secondary free list.
452 wait_while_free_regions_coming();
453 append_secondary_free_list_if_not_empty_with_lock();
454
455 // Policy: Try only empty regions (i.e. already committed first). Maybe we
456 // are lucky enough to find some.
457 first = _hrm.find_contiguous_only_empty(obj_regions);
458 if (first != G1_NO_HRM_INDEX) {
459 _hrm.allocate_free_regions_starting_at(first, obj_regions);
460 }
461 }
462
463 if (first == G1_NO_HRM_INDEX) {
464 // Policy: We could not find enough regions for the humongous object in the
465 // free list. Look through the heap to find a mix of free and uncommitted regions.
466 // If so, try expansion.
467 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
468 if (first != G1_NO_HRM_INDEX) {
469 // We found something. Make sure these regions are committed, i.e. expand
470 // the heap. Alternatively we could do a defragmentation GC.
471 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
472 word_size * HeapWordSize);
473
474
475 _hrm.expand_at(first, obj_regions);
476 g1_policy()->record_new_heap_size(num_regions());
477
478 #ifdef ASSERT
479 for (uint i = first; i < first + obj_regions; ++i) {
480 HeapRegion* hr = region_at(i);
481 assert(hr->is_free(), "sanity");
482 assert(hr->is_empty(), "sanity");
483 assert(is_on_master_free_list(hr), "sanity");
484 }
485 #endif
486 _hrm.allocate_free_regions_starting_at(first, obj_regions);
487 } else {
488 // Policy: Potentially trigger a defragmentation GC.
489 }
490 }
491
492 HeapWord* result = NULL;
493 if (first != G1_NO_HRM_INDEX) {
494 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
495 word_size, context);
496 assert(result != NULL, "it should always return a valid result");
497
498 // A successful humongous object allocation changes the used space
499 // information of the old generation so we need to recalculate the
500 // sizes and update the jstat counters here.
501 g1mm()->update_sizes();
502 }
503
504 verify_region_sets_optional();
505
506 return result;
507 }
508
509 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
510 assert_heap_not_locked_and_not_at_safepoint();
511 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
512
513 uint dummy_gc_count_before;
514 uint dummy_gclocker_retry_count = 0;
515 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
516 }
517
518 HeapWord*
519 G1CollectedHeap::mem_allocate(size_t word_size,
520 bool* gc_overhead_limit_was_exceeded) {
521 assert_heap_not_locked_and_not_at_safepoint();
522
523 // Loop until the allocation is satisfied, or unsatisfied after GC.
524 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
525 uint gc_count_before;
526
527 HeapWord* result = NULL;
528 if (!is_humongous(word_size)) {
529 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
530 } else {
531 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
532 }
533 if (result != NULL) {
534 return result;
535 }
536
537 // Create the garbage collection operation...
538 VM_G1CollectForAllocation op(gc_count_before, word_size);
539 op.set_allocation_context(AllocationContext::current());
540
541 // ...and get the VM thread to execute it.
542 VMThread::execute(&op);
543
544 if (op.prologue_succeeded() && op.pause_succeeded()) {
545 // If the operation was successful we'll return the result even
546 // if it is NULL. If the allocation attempt failed immediately
547 // after a Full GC, it's unlikely we'll be able to allocate now.
548 HeapWord* result = op.result();
549 if (result != NULL && !is_humongous(word_size)) {
550 // Allocations that take place on VM operations do not do any
551 // card dirtying and we have to do it here. We only have to do
552 // this for non-humongous allocations, though.
553 dirty_young_block(result, word_size);
554 }
555 return result;
556 } else {
557 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
558 return NULL;
559 }
560 assert(op.result() == NULL,
561 "the result should be NULL if the VM op did not succeed");
562 }
563
564 // Give a warning if we seem to be looping forever.
565 if ((QueuedAllocationWarningCount > 0) &&
566 (try_count % QueuedAllocationWarningCount == 0)) {
567 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
568 }
569 }
570
571 ShouldNotReachHere();
572 return NULL;
573 }
574
575 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
576 AllocationContext_t context,
577 uint* gc_count_before_ret,
578 uint* gclocker_retry_count_ret) {
579 // Make sure you read the note in attempt_allocation_humongous().
580
581 assert_heap_not_locked_and_not_at_safepoint();
582 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
583 "be called for humongous allocation requests");
584
585 // We should only get here after the first-level allocation attempt
586 // (attempt_allocation()) failed to allocate.
587
588 // We will loop until a) we manage to successfully perform the
589 // allocation or b) we successfully schedule a collection which
590 // fails to perform the allocation. b) is the only case when we'll
591 // return NULL.
592 HeapWord* result = NULL;
593 for (int try_count = 1; /* we'll return */; try_count += 1) {
594 bool should_try_gc;
595 uint gc_count_before;
596
597 {
598 MutexLockerEx x(Heap_lock);
599 result = _allocator->attempt_allocation_locked(word_size, context);
600 if (result != NULL) {
601 return result;
602 }
603
604 if (GC_locker::is_active_and_needs_gc()) {
605 if (g1_policy()->can_expand_young_list()) {
606 // No need for an ergo verbose message here,
607 // can_expand_young_list() does this when it returns true.
608 result = _allocator->attempt_allocation_force(word_size, context);
609 if (result != NULL) {
610 return result;
611 }
612 }
613 should_try_gc = false;
614 } else {
615 // The GCLocker may not be active but the GCLocker initiated
616 // GC may not yet have been performed (GCLocker::needs_gc()
617 // returns true). In this case we do not try this GC and
618 // wait until the GCLocker initiated GC is performed, and
619 // then retry the allocation.
620 if (GC_locker::needs_gc()) {
621 should_try_gc = false;
622 } else {
623 // Read the GC count while still holding the Heap_lock.
624 gc_count_before = total_collections();
625 should_try_gc = true;
626 }
627 }
628 }
629
630 if (should_try_gc) {
631 bool succeeded;
632 result = do_collection_pause(word_size, gc_count_before, &succeeded,
633 GCCause::_g1_inc_collection_pause);
634 if (result != NULL) {
635 assert(succeeded, "only way to get back a non-NULL result");
636 return result;
637 }
638
639 if (succeeded) {
640 // If we get here we successfully scheduled a collection which
641 // failed to allocate. No point in trying to allocate
642 // further. We'll just return NULL.
643 MutexLockerEx x(Heap_lock);
644 *gc_count_before_ret = total_collections();
645 return NULL;
646 }
647 } else {
648 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
649 MutexLockerEx x(Heap_lock);
650 *gc_count_before_ret = total_collections();
651 return NULL;
652 }
653 // The GCLocker is either active or the GCLocker initiated
654 // GC has not yet been performed. Stall until it is and
655 // then retry the allocation.
656 GC_locker::stall_until_clear();
657 (*gclocker_retry_count_ret) += 1;
658 }
659
660 // We can reach here if we were unsuccessful in scheduling a
661 // collection (because another thread beat us to it) or if we were
662 // stalled due to the GC locker. In either can we should retry the
663 // allocation attempt in case another thread successfully
664 // performed a collection and reclaimed enough space. We do the
665 // first attempt (without holding the Heap_lock) here and the
666 // follow-on attempt will be at the start of the next loop
667 // iteration (after taking the Heap_lock).
668 result = _allocator->attempt_allocation(word_size, context);
669 if (result != NULL) {
670 return result;
671 }
672
673 // Give a warning if we seem to be looping forever.
674 if ((QueuedAllocationWarningCount > 0) &&
675 (try_count % QueuedAllocationWarningCount == 0)) {
676 warning("G1CollectedHeap::attempt_allocation_slow() "
677 "retries %d times", try_count);
678 }
679 }
680
681 ShouldNotReachHere();
682 return NULL;
683 }
684
685 void G1CollectedHeap::begin_archive_alloc_range() {
686 assert_at_safepoint(true /* should_be_vm_thread */);
687 if (_archive_allocator == NULL) {
688 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
689 }
690 }
691
692 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
693 // Allocations in archive regions cannot be of a size that would be considered
694 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
695 // may be different at archive-restore time.
696 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
697 }
698
699 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
700 assert_at_safepoint(true /* should_be_vm_thread */);
701 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
702 if (is_archive_alloc_too_large(word_size)) {
703 return NULL;
704 }
705 return _archive_allocator->archive_mem_allocate(word_size);
706 }
707
708 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
709 size_t end_alignment_in_bytes) {
710 assert_at_safepoint(true /* should_be_vm_thread */);
711 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
712
713 // Call complete_archive to do the real work, filling in the MemRegion
714 // array with the archive regions.
715 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
716 delete _archive_allocator;
717 _archive_allocator = NULL;
718 }
719
720 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
721 assert(ranges != NULL, "MemRegion array NULL");
722 assert(count != 0, "No MemRegions provided");
723 MemRegion reserved = _hrm.reserved();
724 for (size_t i = 0; i < count; i++) {
725 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
726 return false;
727 }
728 }
729 return true;
730 }
731
732 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
733 assert(!is_init_completed(), "Expect to be called at JVM init time");
734 assert(ranges != NULL, "MemRegion array NULL");
735 assert(count != 0, "No MemRegions provided");
736 MutexLockerEx x(Heap_lock);
737
738 MemRegion reserved = _hrm.reserved();
739 HeapWord* prev_last_addr = NULL;
740 HeapRegion* prev_last_region = NULL;
741
742 // Temporarily disable pretouching of heap pages. This interface is used
743 // when mmap'ing archived heap data in, so pre-touching is wasted.
744 FlagSetting fs(AlwaysPreTouch, false);
745
746 // Enable archive object checking in G1MarkSweep. We have to let it know
747 // about each archive range, so that objects in those ranges aren't marked.
748 G1MarkSweep::enable_archive_object_check();
749
750 // For each specified MemRegion range, allocate the corresponding G1
751 // regions and mark them as archive regions. We expect the ranges in
752 // ascending starting address order, without overlap.
753 for (size_t i = 0; i < count; i++) {
754 MemRegion curr_range = ranges[i];
755 HeapWord* start_address = curr_range.start();
756 size_t word_size = curr_range.word_size();
757 HeapWord* last_address = curr_range.last();
758 size_t commits = 0;
759
760 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
761 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
762 p2i(start_address), p2i(last_address));
763 guarantee(start_address > prev_last_addr,
764 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
765 p2i(start_address), p2i(prev_last_addr));
766 prev_last_addr = last_address;
767
768 // Check for ranges that start in the same G1 region in which the previous
769 // range ended, and adjust the start address so we don't try to allocate
770 // the same region again. If the current range is entirely within that
771 // region, skip it, just adjusting the recorded top.
772 HeapRegion* start_region = _hrm.addr_to_region(start_address);
773 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
774 start_address = start_region->end();
775 if (start_address > last_address) {
776 increase_used(word_size * HeapWordSize);
777 start_region->set_top(last_address + 1);
778 continue;
779 }
780 start_region->set_top(start_address);
781 curr_range = MemRegion(start_address, last_address + 1);
782 start_region = _hrm.addr_to_region(start_address);
783 }
784
785 // Perform the actual region allocation, exiting if it fails.
786 // Then note how much new space we have allocated.
787 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
788 return false;
789 }
790 increase_used(word_size * HeapWordSize);
791 if (commits != 0) {
792 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
793 HeapRegion::GrainWords * HeapWordSize * commits);
794
795 }
796
797 // Mark each G1 region touched by the range as archive, add it to the old set,
798 // and set the allocation context and top.
799 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
800 HeapRegion* last_region = _hrm.addr_to_region(last_address);
801 prev_last_region = last_region;
802
803 while (curr_region != NULL) {
804 assert(curr_region->is_empty() && !curr_region->is_pinned(),
805 "Region already in use (index %u)", curr_region->hrm_index());
806 curr_region->set_allocation_context(AllocationContext::system());
807 curr_region->set_archive();
808 _hr_printer.alloc(curr_region);
809 _old_set.add(curr_region);
810 if (curr_region != last_region) {
811 curr_region->set_top(curr_region->end());
812 curr_region = _hrm.next_region_in_heap(curr_region);
813 } else {
814 curr_region->set_top(last_address + 1);
815 curr_region = NULL;
816 }
817 }
818
819 // Notify mark-sweep of the archive range.
820 G1MarkSweep::set_range_archive(curr_range, true);
821 }
822 return true;
823 }
824
825 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
826 assert(!is_init_completed(), "Expect to be called at JVM init time");
827 assert(ranges != NULL, "MemRegion array NULL");
828 assert(count != 0, "No MemRegions provided");
829 MemRegion reserved = _hrm.reserved();
830 HeapWord *prev_last_addr = NULL;
831 HeapRegion* prev_last_region = NULL;
832
833 // For each MemRegion, create filler objects, if needed, in the G1 regions
834 // that contain the address range. The address range actually within the
835 // MemRegion will not be modified. That is assumed to have been initialized
836 // elsewhere, probably via an mmap of archived heap data.
837 MutexLockerEx x(Heap_lock);
838 for (size_t i = 0; i < count; i++) {
839 HeapWord* start_address = ranges[i].start();
840 HeapWord* last_address = ranges[i].last();
841
842 assert(reserved.contains(start_address) && reserved.contains(last_address),
843 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
844 p2i(start_address), p2i(last_address));
845 assert(start_address > prev_last_addr,
846 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
847 p2i(start_address), p2i(prev_last_addr));
848
849 HeapRegion* start_region = _hrm.addr_to_region(start_address);
850 HeapRegion* last_region = _hrm.addr_to_region(last_address);
851 HeapWord* bottom_address = start_region->bottom();
852
853 // Check for a range beginning in the same region in which the
854 // previous one ended.
855 if (start_region == prev_last_region) {
856 bottom_address = prev_last_addr + 1;
857 }
858
859 // Verify that the regions were all marked as archive regions by
860 // alloc_archive_regions.
861 HeapRegion* curr_region = start_region;
862 while (curr_region != NULL) {
863 guarantee(curr_region->is_archive(),
864 "Expected archive region at index %u", curr_region->hrm_index());
865 if (curr_region != last_region) {
866 curr_region = _hrm.next_region_in_heap(curr_region);
867 } else {
868 curr_region = NULL;
869 }
870 }
871
872 prev_last_addr = last_address;
873 prev_last_region = last_region;
874
875 // Fill the memory below the allocated range with dummy object(s),
876 // if the region bottom does not match the range start, or if the previous
877 // range ended within the same G1 region, and there is a gap.
878 if (start_address != bottom_address) {
879 size_t fill_size = pointer_delta(start_address, bottom_address);
880 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
881 increase_used(fill_size * HeapWordSize);
882 }
883 }
884 }
885
886 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
887 uint* gc_count_before_ret,
888 uint* gclocker_retry_count_ret) {
889 assert_heap_not_locked_and_not_at_safepoint();
890 assert(!is_humongous(word_size), "attempt_allocation() should not "
891 "be called for humongous allocation requests");
892
893 AllocationContext_t context = AllocationContext::current();
894 HeapWord* result = _allocator->attempt_allocation(word_size, context);
895
896 if (result == NULL) {
897 result = attempt_allocation_slow(word_size,
898 context,
899 gc_count_before_ret,
900 gclocker_retry_count_ret);
901 }
902 assert_heap_not_locked();
903 if (result != NULL) {
904 dirty_young_block(result, word_size);
905 }
906 return result;
907 }
908
909 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
910 assert(!is_init_completed(), "Expect to be called at JVM init time");
911 assert(ranges != NULL, "MemRegion array NULL");
912 assert(count != 0, "No MemRegions provided");
913 MemRegion reserved = _hrm.reserved();
914 HeapWord* prev_last_addr = NULL;
915 HeapRegion* prev_last_region = NULL;
916 size_t size_used = 0;
917 size_t uncommitted_regions = 0;
918
919 // For each Memregion, free the G1 regions that constitute it, and
920 // notify mark-sweep that the range is no longer to be considered 'archive.'
921 MutexLockerEx x(Heap_lock);
922 for (size_t i = 0; i < count; i++) {
923 HeapWord* start_address = ranges[i].start();
924 HeapWord* last_address = ranges[i].last();
925
926 assert(reserved.contains(start_address) && reserved.contains(last_address),
927 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
928 p2i(start_address), p2i(last_address));
929 assert(start_address > prev_last_addr,
930 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
931 p2i(start_address), p2i(prev_last_addr));
932 size_used += ranges[i].byte_size();
933 prev_last_addr = last_address;
934
935 HeapRegion* start_region = _hrm.addr_to_region(start_address);
936 HeapRegion* last_region = _hrm.addr_to_region(last_address);
937
938 // Check for ranges that start in the same G1 region in which the previous
939 // range ended, and adjust the start address so we don't try to free
940 // the same region again. If the current range is entirely within that
941 // region, skip it.
942 if (start_region == prev_last_region) {
943 start_address = start_region->end();
944 if (start_address > last_address) {
945 continue;
946 }
947 start_region = _hrm.addr_to_region(start_address);
948 }
949 prev_last_region = last_region;
950
951 // After verifying that each region was marked as an archive region by
952 // alloc_archive_regions, set it free and empty and uncommit it.
953 HeapRegion* curr_region = start_region;
954 while (curr_region != NULL) {
955 guarantee(curr_region->is_archive(),
956 "Expected archive region at index %u", curr_region->hrm_index());
957 uint curr_index = curr_region->hrm_index();
958 _old_set.remove(curr_region);
959 curr_region->set_free();
960 curr_region->set_top(curr_region->bottom());
961 if (curr_region != last_region) {
962 curr_region = _hrm.next_region_in_heap(curr_region);
963 } else {
964 curr_region = NULL;
965 }
966 _hrm.shrink_at(curr_index, 1);
967 uncommitted_regions++;
968 }
969
970 // Notify mark-sweep that this is no longer an archive range.
971 G1MarkSweep::set_range_archive(ranges[i], false);
972 }
973
974 if (uncommitted_regions != 0) {
975 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
976 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
977 }
978 decrease_used(size_used);
979 }
980
981 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
982 uint* gc_count_before_ret,
983 uint* gclocker_retry_count_ret) {
984 // The structure of this method has a lot of similarities to
985 // attempt_allocation_slow(). The reason these two were not merged
986 // into a single one is that such a method would require several "if
987 // allocation is not humongous do this, otherwise do that"
988 // conditional paths which would obscure its flow. In fact, an early
989 // version of this code did use a unified method which was harder to
990 // follow and, as a result, it had subtle bugs that were hard to
991 // track down. So keeping these two methods separate allows each to
992 // be more readable. It will be good to keep these two in sync as
993 // much as possible.
994
995 assert_heap_not_locked_and_not_at_safepoint();
996 assert(is_humongous(word_size), "attempt_allocation_humongous() "
997 "should only be called for humongous allocations");
998
999 // Humongous objects can exhaust the heap quickly, so we should check if we
1000 // need to start a marking cycle at each humongous object allocation. We do
1001 // the check before we do the actual allocation. The reason for doing it
1002 // before the allocation is that we avoid having to keep track of the newly
1003 // allocated memory while we do a GC.
1004 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1005 word_size)) {
1006 collect(GCCause::_g1_humongous_allocation);
1007 }
1008
1009 // We will loop until a) we manage to successfully perform the
1010 // allocation or b) we successfully schedule a collection which
1011 // fails to perform the allocation. b) is the only case when we'll
1012 // return NULL.
1013 HeapWord* result = NULL;
1014 for (int try_count = 1; /* we'll return */; try_count += 1) {
1015 bool should_try_gc;
1016 uint gc_count_before;
1017
1018 {
1019 MutexLockerEx x(Heap_lock);
1020
1021 // Given that humongous objects are not allocated in young
1022 // regions, we'll first try to do the allocation without doing a
1023 // collection hoping that there's enough space in the heap.
1024 result = humongous_obj_allocate(word_size, AllocationContext::current());
1025 if (result != NULL) {
1026 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1027 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1028 return result;
1029 }
1030
1031 if (GC_locker::is_active_and_needs_gc()) {
1032 should_try_gc = false;
1033 } else {
1034 // The GCLocker may not be active but the GCLocker initiated
1035 // GC may not yet have been performed (GCLocker::needs_gc()
1036 // returns true). In this case we do not try this GC and
1037 // wait until the GCLocker initiated GC is performed, and
1038 // then retry the allocation.
1039 if (GC_locker::needs_gc()) {
1040 should_try_gc = false;
1041 } else {
1042 // Read the GC count while still holding the Heap_lock.
1043 gc_count_before = total_collections();
1044 should_try_gc = true;
1045 }
1046 }
1047 }
1048
1049 if (should_try_gc) {
1050 // If we failed to allocate the humongous object, we should try to
1051 // do a collection pause (if we're allowed) in case it reclaims
1052 // enough space for the allocation to succeed after the pause.
1053
1054 bool succeeded;
1055 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1056 GCCause::_g1_humongous_allocation);
1057 if (result != NULL) {
1058 assert(succeeded, "only way to get back a non-NULL result");
1059 return result;
1060 }
1061
1062 if (succeeded) {
1063 // If we get here we successfully scheduled a collection which
1064 // failed to allocate. No point in trying to allocate
1065 // further. We'll just return NULL.
1066 MutexLockerEx x(Heap_lock);
1067 *gc_count_before_ret = total_collections();
1068 return NULL;
1069 }
1070 } else {
1071 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1072 MutexLockerEx x(Heap_lock);
1073 *gc_count_before_ret = total_collections();
1074 return NULL;
1075 }
1076 // The GCLocker is either active or the GCLocker initiated
1077 // GC has not yet been performed. Stall until it is and
1078 // then retry the allocation.
1079 GC_locker::stall_until_clear();
1080 (*gclocker_retry_count_ret) += 1;
1081 }
1082
1083 // We can reach here if we were unsuccessful in scheduling a
1084 // collection (because another thread beat us to it) or if we were
1085 // stalled due to the GC locker. In either can we should retry the
1086 // allocation attempt in case another thread successfully
1087 // performed a collection and reclaimed enough space. Give a
1088 // warning if we seem to be looping forever.
1089
1090 if ((QueuedAllocationWarningCount > 0) &&
1091 (try_count % QueuedAllocationWarningCount == 0)) {
1092 warning("G1CollectedHeap::attempt_allocation_humongous() "
1093 "retries %d times", try_count);
1094 }
1095 }
1096
1097 ShouldNotReachHere();
1098 return NULL;
1099 }
1100
1101 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1102 AllocationContext_t context,
1103 bool expect_null_mutator_alloc_region) {
1104 assert_at_safepoint(true /* should_be_vm_thread */);
1105 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1106 "the current alloc region was unexpectedly found to be non-NULL");
1107
1108 if (!is_humongous(word_size)) {
1109 return _allocator->attempt_allocation_locked(word_size, context);
1110 } else {
1111 HeapWord* result = humongous_obj_allocate(word_size, context);
1112 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1113 collector_state()->set_initiate_conc_mark_if_possible(true);
1114 }
1115 return result;
1116 }
1117
1118 ShouldNotReachHere();
1119 }
1120
1121 class PostMCRemSetClearClosure: public HeapRegionClosure {
1122 G1CollectedHeap* _g1h;
1123 ModRefBarrierSet* _mr_bs;
1124 public:
1125 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1126 _g1h(g1h), _mr_bs(mr_bs) {}
1127
1128 bool doHeapRegion(HeapRegion* r) {
1129 HeapRegionRemSet* hrrs = r->rem_set();
1130
1131 _g1h->reset_gc_time_stamps(r);
1132
1133 if (r->is_continues_humongous()) {
1134 // We'll assert that the strong code root list and RSet is empty
1135 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1136 assert(hrrs->occupied() == 0, "RSet should be empty");
1137 } else {
1138 hrrs->clear();
1139 }
1140 // You might think here that we could clear just the cards
1141 // corresponding to the used region. But no: if we leave a dirty card
1142 // in a region we might allocate into, then it would prevent that card
1143 // from being enqueued, and cause it to be missed.
1144 // Re: the performance cost: we shouldn't be doing full GC anyway!
1145 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1146
1147 return false;
1148 }
1149 };
1150
1151 void G1CollectedHeap::clear_rsets_post_compaction() {
1152 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1153 heap_region_iterate(&rs_clear);
1154 }
1155
1156 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1157 G1CollectedHeap* _g1h;
1158 UpdateRSOopClosure _cl;
1159 public:
1160 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1161 _cl(g1->g1_rem_set(), worker_i),
1162 _g1h(g1)
1163 { }
1164
1165 bool doHeapRegion(HeapRegion* r) {
1166 if (!r->is_continues_humongous()) {
1167 _cl.set_from(r);
1168 r->oop_iterate(&_cl);
1169 }
1170 return false;
1171 }
1172 };
1173
1174 class ParRebuildRSTask: public AbstractGangTask {
1175 G1CollectedHeap* _g1;
1176 HeapRegionClaimer _hrclaimer;
1177
1178 public:
1179 ParRebuildRSTask(G1CollectedHeap* g1) :
1180 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1181
1182 void work(uint worker_id) {
1183 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1184 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1185 }
1186 };
1187
1188 class PostCompactionPrinterClosure: public HeapRegionClosure {
1189 private:
1190 G1HRPrinter* _hr_printer;
1191 public:
1192 bool doHeapRegion(HeapRegion* hr) {
1193 assert(!hr->is_young(), "not expecting to find young regions");
1194 _hr_printer->post_compaction(hr);
1195 return false;
1196 }
1197
1198 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1199 : _hr_printer(hr_printer) { }
1200 };
1201
1202 void G1CollectedHeap::print_hrm_post_compaction() {
1203 if (_hr_printer.is_active()) {
1204 PostCompactionPrinterClosure cl(hr_printer());
1205 heap_region_iterate(&cl);
1206 }
1207
1208 }
1209
1210 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1211 bool clear_all_soft_refs) {
1212 assert_at_safepoint(true /* should_be_vm_thread */);
1213
1214 if (GC_locker::check_active_before_gc()) {
1215 return false;
1216 }
1217
1218 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1219 gc_timer->register_gc_start();
1220
1221 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1222 GCIdMark gc_id_mark;
1223 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1224
1225 SvcGCMarker sgcm(SvcGCMarker::FULL);
1226 ResourceMark rm;
1227
1228 print_heap_before_gc();
1229 trace_heap_before_gc(gc_tracer);
1230
1231 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1232
1233 verify_region_sets_optional();
1234
1235 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1236 collector_policy()->should_clear_all_soft_refs();
1237
1238 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1239
1240 {
1241 IsGCActiveMark x;
1242
1243 // Timing
1244 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1245 GCTraceCPUTime tcpu;
1246
1247 {
1248 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1249 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1250 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1251
1252 g1_policy()->record_full_collection_start();
1253
1254 // Note: When we have a more flexible GC logging framework that
1255 // allows us to add optional attributes to a GC log record we
1256 // could consider timing and reporting how long we wait in the
1257 // following two methods.
1258 wait_while_free_regions_coming();
1259 // If we start the compaction before the CM threads finish
1260 // scanning the root regions we might trip them over as we'll
1261 // be moving objects / updating references. So let's wait until
1262 // they are done. By telling them to abort, they should complete
1263 // early.
1264 _cm->root_regions()->abort();
1265 _cm->root_regions()->wait_until_scan_finished();
1266 append_secondary_free_list_if_not_empty_with_lock();
1267
1268 gc_prologue(true);
1269 increment_total_collections(true /* full gc */);
1270 increment_old_marking_cycles_started();
1271
1272 assert(used() == recalculate_used(), "Should be equal");
1273
1274 verify_before_gc();
1275
1276 check_bitmaps("Full GC Start");
1277 pre_full_gc_dump(gc_timer);
1278
1279 #if defined(COMPILER2) || INCLUDE_JVMCI
1280 DerivedPointerTable::clear();
1281 #endif
1282
1283 // Disable discovery and empty the discovered lists
1284 // for the CM ref processor.
1285 ref_processor_cm()->disable_discovery();
1286 ref_processor_cm()->abandon_partial_discovery();
1287 ref_processor_cm()->verify_no_references_recorded();
1288
1289 // Abandon current iterations of concurrent marking and concurrent
1290 // refinement, if any are in progress. We have to do this before
1291 // wait_until_scan_finished() below.
1292 concurrent_mark()->abort();
1293
1294 // Make sure we'll choose a new allocation region afterwards.
1295 _allocator->release_mutator_alloc_region();
1296 _allocator->abandon_gc_alloc_regions();
1297 g1_rem_set()->cleanupHRRS();
1298
1299 // We may have added regions to the current incremental collection
1300 // set between the last GC or pause and now. We need to clear the
1301 // incremental collection set and then start rebuilding it afresh
1302 // after this full GC.
1303 abandon_collection_set(g1_policy()->inc_cset_head());
1304 g1_policy()->clear_incremental_cset();
1305 g1_policy()->stop_incremental_cset_building();
1306
1307 tear_down_region_sets(false /* free_list_only */);
1308 collector_state()->set_gcs_are_young(true);
1309
1310 // See the comments in g1CollectedHeap.hpp and
1311 // G1CollectedHeap::ref_processing_init() about
1312 // how reference processing currently works in G1.
1313
1314 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1315 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1316
1317 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1318 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1319
1320 ref_processor_stw()->enable_discovery();
1321 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1322
1323 // Do collection work
1324 {
1325 HandleMark hm; // Discard invalid handles created during gc
1326 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1327 }
1328
1329 assert(num_free_regions() == 0, "we should not have added any free regions");
1330 rebuild_region_sets(false /* free_list_only */);
1331
1332 // Enqueue any discovered reference objects that have
1333 // not been removed from the discovered lists.
1334 ref_processor_stw()->enqueue_discovered_references();
1335
1336 #if defined(COMPILER2) || INCLUDE_JVMCI
1337 DerivedPointerTable::update_pointers();
1338 #endif
1339
1340 MemoryService::track_memory_usage();
1341
1342 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1343 ref_processor_stw()->verify_no_references_recorded();
1344
1345 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1346 ClassLoaderDataGraph::purge();
1347 MetaspaceAux::verify_metrics();
1348
1349 // Note: since we've just done a full GC, concurrent
1350 // marking is no longer active. Therefore we need not
1351 // re-enable reference discovery for the CM ref processor.
1352 // That will be done at the start of the next marking cycle.
1353 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 reset_gc_time_stamp();
1357 // Since everything potentially moved, we will clear all remembered
1358 // sets, and clear all cards. Later we will rebuild remembered
1359 // sets. We will also reset the GC time stamps of the regions.
1360 clear_rsets_post_compaction();
1361 check_gc_time_stamps();
1362
1363 resize_if_necessary_after_full_collection();
1364
1365 // We should do this after we potentially resize the heap so
1366 // that all the COMMIT / UNCOMMIT events are generated before
1367 // the compaction events.
1368 print_hrm_post_compaction();
1369
1370 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1371 if (hot_card_cache->use_cache()) {
1372 hot_card_cache->reset_card_counts();
1373 hot_card_cache->reset_hot_cache();
1374 }
1375
1376 // Rebuild remembered sets of all regions.
1377 uint n_workers =
1378 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1379 workers()->active_workers(),
1380 Threads::number_of_non_daemon_threads());
1381 workers()->set_active_workers(n_workers);
1382
1383 ParRebuildRSTask rebuild_rs_task(this);
1384 workers()->run_task(&rebuild_rs_task);
1385
1386 // Rebuild the strong code root lists for each region
1387 rebuild_strong_code_roots();
1388
1389 if (true) { // FIXME
1390 MetaspaceGC::compute_new_size();
1391 }
1392
1393 #ifdef TRACESPINNING
1394 ParallelTaskTerminator::print_termination_counts();
1395 #endif
1396
1397 // Discard all rset updates
1398 JavaThread::dirty_card_queue_set().abandon_logs();
1399 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1400
1401 _young_list->reset_sampled_info();
1402 // At this point there should be no regions in the
1403 // entire heap tagged as young.
1404 assert(check_young_list_empty(true /* check_heap */),
1405 "young list should be empty at this point");
1406
1407 // Update the number of full collections that have been completed.
1408 increment_old_marking_cycles_completed(false /* concurrent */);
1409
1410 _hrm.verify_optional();
1411 verify_region_sets_optional();
1412
1413 verify_after_gc();
1414
1415 // Clear the previous marking bitmap, if needed for bitmap verification.
1416 // Note we cannot do this when we clear the next marking bitmap in
1417 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1418 // objects marked during a full GC against the previous bitmap.
1419 // But we need to clear it before calling check_bitmaps below since
1420 // the full GC has compacted objects and updated TAMS but not updated
1421 // the prev bitmap.
1422 if (G1VerifyBitmaps) {
1423 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1424 }
1425 check_bitmaps("Full GC End");
1426
1427 // Start a new incremental collection set for the next pause
1428 assert(g1_policy()->collection_set() == NULL, "must be");
1429 g1_policy()->start_incremental_cset_building();
1430
1431 clear_cset_fast_test();
1432
1433 _allocator->init_mutator_alloc_region();
1434
1435 g1_policy()->record_full_collection_end();
1436
1437 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1438 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1439 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1440 // before any GC notifications are raised.
1441 g1mm()->update_sizes();
1442
1443 gc_epilogue(true);
1444 }
1445
1446 g1_policy()->print_detailed_heap_transition();
1447
1448 print_heap_after_gc();
1449 trace_heap_after_gc(gc_tracer);
1450
1451 post_full_gc_dump(gc_timer);
1452
1453 gc_timer->register_gc_end();
1454 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1455 }
1456
1457 return true;
1458 }
1459
1460 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1461 // Currently, there is no facility in the do_full_collection(bool) API to notify
1462 // the caller that the collection did not succeed (e.g., because it was locked
1463 // out by the GC locker). So, right now, we'll ignore the return value.
1464 bool dummy = do_full_collection(true, /* explicit_gc */
1465 clear_all_soft_refs);
1466 }
1467
1468 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1469 // Include bytes that will be pre-allocated to support collections, as "used".
1470 const size_t used_after_gc = used();
1471 const size_t capacity_after_gc = capacity();
1472 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1473
1474 // This is enforced in arguments.cpp.
1475 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1476 "otherwise the code below doesn't make sense");
1477
1478 // We don't have floating point command-line arguments
1479 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1480 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1481 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1482 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1483
1484 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1485 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1486
1487 // We have to be careful here as these two calculations can overflow
1488 // 32-bit size_t's.
1489 double used_after_gc_d = (double) used_after_gc;
1490 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1491 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1492
1493 // Let's make sure that they are both under the max heap size, which
1494 // by default will make them fit into a size_t.
1495 double desired_capacity_upper_bound = (double) max_heap_size;
1496 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1497 desired_capacity_upper_bound);
1498 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1499 desired_capacity_upper_bound);
1500
1501 // We can now safely turn them into size_t's.
1502 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1503 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1504
1505 // This assert only makes sense here, before we adjust them
1506 // with respect to the min and max heap size.
1507 assert(minimum_desired_capacity <= maximum_desired_capacity,
1508 "minimum_desired_capacity = " SIZE_FORMAT ", "
1509 "maximum_desired_capacity = " SIZE_FORMAT,
1510 minimum_desired_capacity, maximum_desired_capacity);
1511
1512 // Should not be greater than the heap max size. No need to adjust
1513 // it with respect to the heap min size as it's a lower bound (i.e.,
1514 // we'll try to make the capacity larger than it, not smaller).
1515 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1516 // Should not be less than the heap min size. No need to adjust it
1517 // with respect to the heap max size as it's an upper bound (i.e.,
1518 // we'll try to make the capacity smaller than it, not greater).
1519 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1520
1521 if (capacity_after_gc < minimum_desired_capacity) {
1522 // Don't expand unless it's significant
1523 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1524
1525 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1526 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1527 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1528
1529 expand(expand_bytes);
1530
1531 // No expansion, now see if we want to shrink
1532 } else if (capacity_after_gc > maximum_desired_capacity) {
1533 // Capacity too large, compute shrinking size
1534 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1535
1536 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1537 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1538 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1539
1540 shrink(shrink_bytes);
1541 }
1542 }
1543
1544 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1545 AllocationContext_t context,
1546 bool do_gc,
1547 bool clear_all_soft_refs,
1548 bool expect_null_mutator_alloc_region,
1549 bool* gc_succeeded) {
1550 *gc_succeeded = true;
1551 // Let's attempt the allocation first.
1552 HeapWord* result =
1553 attempt_allocation_at_safepoint(word_size,
1554 context,
1555 expect_null_mutator_alloc_region);
1556 if (result != NULL) {
1557 assert(*gc_succeeded, "sanity");
1558 return result;
1559 }
1560
1561 // In a G1 heap, we're supposed to keep allocation from failing by
1562 // incremental pauses. Therefore, at least for now, we'll favor
1563 // expansion over collection. (This might change in the future if we can
1564 // do something smarter than full collection to satisfy a failed alloc.)
1565 result = expand_and_allocate(word_size, context);
1566 if (result != NULL) {
1567 assert(*gc_succeeded, "sanity");
1568 return result;
1569 }
1570
1571 if (do_gc) {
1572 // Expansion didn't work, we'll try to do a Full GC.
1573 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1574 clear_all_soft_refs);
1575 }
1576
1577 return NULL;
1578 }
1579
1580 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1581 AllocationContext_t context,
1582 bool* succeeded) {
1583 assert_at_safepoint(true /* should_be_vm_thread */);
1584
1585 // Attempts to allocate followed by Full GC.
1586 HeapWord* result =
1587 satisfy_failed_allocation_helper(word_size,
1588 context,
1589 true, /* do_gc */
1590 false, /* clear_all_soft_refs */
1591 false, /* expect_null_mutator_alloc_region */
1592 succeeded);
1593
1594 if (result != NULL || !*succeeded) {
1595 return result;
1596 }
1597
1598 // Attempts to allocate followed by Full GC that will collect all soft references.
1599 result = satisfy_failed_allocation_helper(word_size,
1600 context,
1601 true, /* do_gc */
1602 true, /* clear_all_soft_refs */
1603 true, /* expect_null_mutator_alloc_region */
1604 succeeded);
1605
1606 if (result != NULL || !*succeeded) {
1607 return result;
1608 }
1609
1610 // Attempts to allocate, no GC
1611 result = satisfy_failed_allocation_helper(word_size,
1612 context,
1613 false, /* do_gc */
1614 false, /* clear_all_soft_refs */
1615 true, /* expect_null_mutator_alloc_region */
1616 succeeded);
1617
1618 if (result != NULL) {
1619 assert(*succeeded, "sanity");
1620 return result;
1621 }
1622
1623 assert(!collector_policy()->should_clear_all_soft_refs(),
1624 "Flag should have been handled and cleared prior to this point");
1625
1626 // What else? We might try synchronous finalization later. If the total
1627 // space available is large enough for the allocation, then a more
1628 // complete compaction phase than we've tried so far might be
1629 // appropriate.
1630 assert(*succeeded, "sanity");
1631 return NULL;
1632 }
1633
1634 // Attempting to expand the heap sufficiently
1635 // to support an allocation of the given "word_size". If
1636 // successful, perform the allocation and return the address of the
1637 // allocated block, or else "NULL".
1638
1639 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1640 assert_at_safepoint(true /* should_be_vm_thread */);
1641
1642 verify_region_sets_optional();
1643
1644 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1645 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1646 word_size * HeapWordSize);
1647
1648
1649 if (expand(expand_bytes)) {
1650 _hrm.verify_optional();
1651 verify_region_sets_optional();
1652 return attempt_allocation_at_safepoint(word_size,
1653 context,
1654 false /* expect_null_mutator_alloc_region */);
1655 }
1656 return NULL;
1657 }
1658
1659 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1660 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1661 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1662 HeapRegion::GrainBytes);
1663
1664 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1665 expand_bytes, aligned_expand_bytes);
1666
1667 if (is_maximal_no_gc()) {
1668 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1669 return false;
1670 }
1671
1672 double expand_heap_start_time_sec = os::elapsedTime();
1673 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1674 assert(regions_to_expand > 0, "Must expand by at least one region");
1675
1676 uint expanded_by = _hrm.expand_by(regions_to_expand);
1677 if (expand_time_ms != NULL) {
1678 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1679 }
1680
1681 if (expanded_by > 0) {
1682 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1683 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1684 g1_policy()->record_new_heap_size(num_regions());
1685 } else {
1686 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1687
1688 // The expansion of the virtual storage space was unsuccessful.
1689 // Let's see if it was because we ran out of swap.
1690 if (G1ExitOnExpansionFailure &&
1691 _hrm.available() >= regions_to_expand) {
1692 // We had head room...
1693 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1694 }
1695 }
1696 return regions_to_expand > 0;
1697 }
1698
1699 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1700 size_t aligned_shrink_bytes =
1701 ReservedSpace::page_align_size_down(shrink_bytes);
1702 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1703 HeapRegion::GrainBytes);
1704 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1705
1706 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1707 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1708
1709
1710 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",
1711 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1712 if (num_regions_removed > 0) {
1713 g1_policy()->record_new_heap_size(num_regions());
1714 } else {
1715 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1716 }
1717 }
1718
1719 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1720 verify_region_sets_optional();
1721
1722 // We should only reach here at the end of a Full GC which means we
1723 // should not not be holding to any GC alloc regions. The method
1724 // below will make sure of that and do any remaining clean up.
1725 _allocator->abandon_gc_alloc_regions();
1726
1727 // Instead of tearing down / rebuilding the free lists here, we
1728 // could instead use the remove_all_pending() method on free_list to
1729 // remove only the ones that we need to remove.
1730 tear_down_region_sets(true /* free_list_only */);
1731 shrink_helper(shrink_bytes);
1732 rebuild_region_sets(true /* free_list_only */);
1733
1734 _hrm.verify_optional();
1735 verify_region_sets_optional();
1736 }
1737
1738 // Public methods.
1739
1740 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1741 CollectedHeap(),
1742 _g1_policy(policy_),
1743 _dirty_card_queue_set(false),
1744 _is_alive_closure_cm(this),
1745 _is_alive_closure_stw(this),
1746 _ref_processor_cm(NULL),
1747 _ref_processor_stw(NULL),
1748 _bot_shared(NULL),
1749 _cg1r(NULL),
1750 _g1mm(NULL),
1751 _refine_cte_cl(NULL),
1752 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1753 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1754 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1755 _humongous_reclaim_candidates(),
1756 _has_humongous_reclaim_candidates(false),
1757 _archive_allocator(NULL),
1758 _free_regions_coming(false),
1759 _young_list(new YoungList(this)),
1760 _gc_time_stamp(0),
1761 _summary_bytes_used(0),
1762 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1763 _old_evac_stats(OldPLABSize, PLABWeight),
1764 _expand_heap_after_alloc_failure(true),
1765 _old_marking_cycles_started(0),
1766 _old_marking_cycles_completed(0),
1767 _heap_summary_sent(false),
1768 _in_cset_fast_test(),
1769 _dirty_cards_region_list(NULL),
1770 _worker_cset_start_region(NULL),
1771 _worker_cset_start_region_time_stamp(NULL),
1772 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1773 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1774 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1775 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1776
1777 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778 /* are_GC_task_threads */true,
1779 /* are_ConcurrentGC_threads */false);
1780 _workers->initialize_workers();
1781
1782 _allocator = G1Allocator::create_allocator(this);
1783 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1784
1785 // Override the default _filler_array_max_size so that no humongous filler
1786 // objects are created.
1787 _filler_array_max_size = _humongous_object_threshold_in_words;
1788
1789 uint n_queues = ParallelGCThreads;
1790 _task_queues = new RefToScanQueueSet(n_queues);
1791
1792 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1793 assert(n_rem_sets > 0, "Invariant.");
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
1895 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1896 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1897 G1RegionToSpaceMapper* heap_storage =
1898 G1RegionToSpaceMapper::create_mapper(g1_rs,
1899 g1_rs.size(),
1900 page_size,
1901 HeapRegion::GrainBytes,
1902 1,
1903 mtJavaHeap);
1904 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1905 max_byte_size, page_size,
1906 heap_rs.base(),
1907 heap_rs.size());
1908 heap_storage->set_mapping_changed_listener(&_listener);
1909
1910 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1911 G1RegionToSpaceMapper* bot_storage =
1912 create_aux_memory_mapper("Block offset table",
1913 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1914 G1BlockOffsetSharedArray::heap_map_factor());
1915
1916 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1917 G1RegionToSpaceMapper* cardtable_storage =
1918 create_aux_memory_mapper("Card table",
1919 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1920 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1921
1922 G1RegionToSpaceMapper* card_counts_storage =
1923 create_aux_memory_mapper("Card counts table",
1924 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1925 G1CardCounts::heap_map_factor());
1926
1927 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1928 G1RegionToSpaceMapper* prev_bitmap_storage =
1929 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1930 G1RegionToSpaceMapper* next_bitmap_storage =
1931 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1932
1933 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1934 g1_barrier_set()->initialize(cardtable_storage);
1935 // Do later initialization work for concurrent refinement.
1936 _cg1r->init(card_counts_storage);
1937
1938 // 6843694 - ensure that the maximum region index can fit
1939 // in the remembered set structures.
1940 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1941 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1942
1943 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1944 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1945 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1946 "too many cards per region");
1947
1948 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1949
1950 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1951
1952 {
1953 HeapWord* start = _hrm.reserved().start();
1954 HeapWord* end = _hrm.reserved().end();
1955 size_t granularity = HeapRegion::GrainBytes;
1956
1957 _in_cset_fast_test.initialize(start, end, granularity);
1958 _humongous_reclaim_candidates.initialize(start, end, granularity);
1959 }
1960
1961 // Create the ConcurrentMark data structure and thread.
1962 // (Must do this late, so that "max_regions" is defined.)
1963 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1964 if (_cm == NULL || !_cm->completed_initialization()) {
1965 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1966 return JNI_ENOMEM;
1967 }
1968 _cmThread = _cm->cmThread();
1969
1970 // Initialize the from_card cache structure of HeapRegionRemSet.
1971 HeapRegionRemSet::init_heap(max_regions());
1972
1973 // Now expand into the initial heap size.
1974 if (!expand(init_byte_size)) {
1975 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1976 return JNI_ENOMEM;
1977 }
1978
1979 // Perform any initialization actions delegated to the policy.
1980 g1_policy()->init();
1981
1982 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1983 SATB_Q_FL_lock,
1984 G1SATBProcessCompletedThreshold,
1985 Shared_SATB_Q_lock);
1986
1987 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1988 DirtyCardQ_CBL_mon,
1989 DirtyCardQ_FL_lock,
1990 concurrent_g1_refine()->yellow_zone(),
1991 concurrent_g1_refine()->red_zone(),
1992 Shared_DirtyCardQ_lock);
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_info(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 (GC_locker::is_active_and_needs_gc()) {
2403 GC_locker::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 result = _worker_cset_start_region[worker_i - 1];
2558 }
2559
2560 for (uint i = start_ind; i < end_ind; i++) {
2561 result = result->next_in_collection_set();
2562 }
2563
2564 // Note: the calculated starting heap region may be NULL
2565 // (when the collection set is empty).
2566 assert(result == NULL || result->in_collection_set(), "sanity");
2567 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2568 "should be updated only once per pause");
2569 _worker_cset_start_region[worker_i] = result;
2570 OrderAccess::storestore();
2571 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2572 return result;
2573 }
2574
2575 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2576 HeapRegion* r = g1_policy()->collection_set();
2577 while (r != NULL) {
2578 HeapRegion* next = r->next_in_collection_set();
2579 if (cl->doHeapRegion(r)) {
2580 cl->incomplete();
2581 return;
2582 }
2583 r = next;
2584 }
2585 }
2586
2587 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2588 HeapRegionClosure *cl) {
2589 if (r == NULL) {
2590 // The CSet is empty so there's nothing to do.
2591 return;
2592 }
2593
2594 assert(r->in_collection_set(),
2595 "Start region must be a member of the collection set.");
2596 HeapRegion* cur = r;
2597 while (cur != NULL) {
2598 HeapRegion* next = cur->next_in_collection_set();
2599 if (cl->doHeapRegion(cur) && false) {
2600 cl->incomplete();
2601 return;
2602 }
2603 cur = next;
2604 }
2605 cur = g1_policy()->collection_set();
2606 while (cur != r) {
2607 HeapRegion* next = cur->next_in_collection_set();
2608 if (cl->doHeapRegion(cur) && false) {
2609 cl->incomplete();
2610 return;
2611 }
2612 cur = next;
2613 }
2614 }
2615
2616 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2617 HeapRegion* result = _hrm.next_region_in_heap(from);
2618 while (result != NULL && result->is_pinned()) {
2619 result = _hrm.next_region_in_heap(result);
2620 }
2621 return result;
2622 }
2623
2624 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2625 HeapRegion* hr = heap_region_containing(addr);
2626 return hr->block_start(addr);
2627 }
2628
2629 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2630 HeapRegion* hr = heap_region_containing(addr);
2631 return hr->block_size(addr);
2632 }
2633
2634 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2635 HeapRegion* hr = heap_region_containing(addr);
2636 return hr->block_is_obj(addr);
2637 }
2638
2639 bool G1CollectedHeap::supports_tlab_allocation() const {
2640 return true;
2641 }
2642
2643 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2644 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2645 }
2646
2647 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2648 return young_list()->eden_used_bytes();
2649 }
2650
2651 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2652 // must be equal to the humongous object limit.
2653 size_t G1CollectedHeap::max_tlab_size() const {
2654 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2655 }
2656
2657 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2658 AllocationContext_t context = AllocationContext::current();
2659 return _allocator->unsafe_max_tlab_alloc(context);
2660 }
2661
2662 size_t G1CollectedHeap::max_capacity() const {
2663 return _hrm.reserved().byte_size();
2664 }
2665
2666 jlong G1CollectedHeap::millis_since_last_gc() {
2667 // assert(false, "NYI");
2668 return 0;
2669 }
2670
2671 void G1CollectedHeap::prepare_for_verify() {
2672 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2673 ensure_parsability(false);
2674 }
2675 g1_rem_set()->prepare_for_verify();
2676 }
2677
2678 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2679 VerifyOption vo) {
2680 switch (vo) {
2681 case VerifyOption_G1UsePrevMarking:
2682 return hr->obj_allocated_since_prev_marking(obj);
2683 case VerifyOption_G1UseNextMarking:
2684 return hr->obj_allocated_since_next_marking(obj);
2685 case VerifyOption_G1UseMarkWord:
2686 return false;
2687 default:
2688 ShouldNotReachHere();
2689 }
2690 return false; // keep some compilers happy
2691 }
2692
2693 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2694 switch (vo) {
2695 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2696 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2697 case VerifyOption_G1UseMarkWord: return NULL;
2698 default: ShouldNotReachHere();
2699 }
2700 return NULL; // keep some compilers happy
2701 }
2702
2703 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2704 switch (vo) {
2705 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2706 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2707 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2708 default: ShouldNotReachHere();
2709 }
2710 return false; // keep some compilers happy
2711 }
2712
2713 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2714 switch (vo) {
2715 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2716 case VerifyOption_G1UseNextMarking: return "NTAMS";
2717 case VerifyOption_G1UseMarkWord: return "NONE";
2718 default: ShouldNotReachHere();
2719 }
2720 return NULL; // keep some compilers happy
2721 }
2722
2723 class VerifyRootsClosure: public OopClosure {
2724 private:
2725 G1CollectedHeap* _g1h;
2726 VerifyOption _vo;
2727 bool _failures;
2728 public:
2729 // _vo == UsePrevMarking -> use "prev" marking information,
2730 // _vo == UseNextMarking -> use "next" marking information,
2731 // _vo == UseMarkWord -> use mark word from object header.
2732 VerifyRootsClosure(VerifyOption vo) :
2733 _g1h(G1CollectedHeap::heap()),
2734 _vo(vo),
2735 _failures(false) { }
2736
2737 bool failures() { return _failures; }
2738
2739 template <class T> void do_oop_nv(T* p) {
2740 T heap_oop = oopDesc::load_heap_oop(p);
2741 if (!oopDesc::is_null(heap_oop)) {
2742 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2743 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2744 LogHandle(gc, verify) log;
2745 log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2746 if (_vo == VerifyOption_G1UseMarkWord) {
2747 log.info(" Mark word: " PTR_FORMAT, p2i(obj->mark()));
2748 }
2749 ResourceMark rm;
2750 obj->print_on(log.info_stream());
2751 _failures = true;
2752 }
2753 }
2754 }
2755
2756 void do_oop(oop* p) { do_oop_nv(p); }
2757 void do_oop(narrowOop* p) { do_oop_nv(p); }
2758 };
2759
2760 class G1VerifyCodeRootOopClosure: public OopClosure {
2761 G1CollectedHeap* _g1h;
2762 OopClosure* _root_cl;
2763 nmethod* _nm;
2764 VerifyOption _vo;
2765 bool _failures;
2766
2767 template <class T> void do_oop_work(T* p) {
2768 // First verify that this root is live
2769 _root_cl->do_oop(p);
2770
2771 if (!G1VerifyHeapRegionCodeRoots) {
2772 // We're not verifying the code roots attached to heap region.
2773 return;
2774 }
2775
2776 // Don't check the code roots during marking verification in a full GC
2777 if (_vo == VerifyOption_G1UseMarkWord) {
2778 return;
2779 }
2780
2781 // Now verify that the current nmethod (which contains p) is
2782 // in the code root list of the heap region containing the
2783 // object referenced by p.
2784
2785 T heap_oop = oopDesc::load_heap_oop(p);
2786 if (!oopDesc::is_null(heap_oop)) {
2787 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2788
2789 // Now fetch the region containing the object
2790 HeapRegion* hr = _g1h->heap_region_containing(obj);
2791 HeapRegionRemSet* hrrs = hr->rem_set();
2792 // Verify that the strong code root list for this region
2793 // contains the nmethod
2794 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2795 log_info(gc, verify)("Code root location " PTR_FORMAT " "
2796 "from nmethod " PTR_FORMAT " not in strong "
2797 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2798 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2799 _failures = true;
2800 }
2801 }
2802 }
2803
2804 public:
2805 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2806 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2807
2808 void do_oop(oop* p) { do_oop_work(p); }
2809 void do_oop(narrowOop* p) { do_oop_work(p); }
2810
2811 void set_nmethod(nmethod* nm) { _nm = nm; }
2812 bool failures() { return _failures; }
2813 };
2814
2815 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2816 G1VerifyCodeRootOopClosure* _oop_cl;
2817
2818 public:
2819 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2820 _oop_cl(oop_cl) {}
2821
2822 void do_code_blob(CodeBlob* cb) {
2823 nmethod* nm = cb->as_nmethod_or_null();
2824 if (nm != NULL) {
2825 _oop_cl->set_nmethod(nm);
2826 nm->oops_do(_oop_cl);
2827 }
2828 }
2829 };
2830
2831 class YoungRefCounterClosure : public OopClosure {
2832 G1CollectedHeap* _g1h;
2833 int _count;
2834 public:
2835 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2836 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2837 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2838
2839 int count() { return _count; }
2840 void reset_count() { _count = 0; };
2841 };
2842
2843 class VerifyKlassClosure: public KlassClosure {
2844 YoungRefCounterClosure _young_ref_counter_closure;
2845 OopClosure *_oop_closure;
2846 public:
2847 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2848 void do_klass(Klass* k) {
2849 k->oops_do(_oop_closure);
2850
2851 _young_ref_counter_closure.reset_count();
2852 k->oops_do(&_young_ref_counter_closure);
2853 if (_young_ref_counter_closure.count() > 0) {
2854 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2855 }
2856 }
2857 };
2858
2859 class VerifyLivenessOopClosure: public OopClosure {
2860 G1CollectedHeap* _g1h;
2861 VerifyOption _vo;
2862 public:
2863 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2864 _g1h(g1h), _vo(vo)
2865 { }
2866 void do_oop(narrowOop *p) { do_oop_work(p); }
2867 void do_oop( oop *p) { do_oop_work(p); }
2868
2869 template <class T> void do_oop_work(T *p) {
2870 oop obj = oopDesc::load_decode_heap_oop(p);
2871 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2872 "Dead object referenced by a not dead object");
2873 }
2874 };
2875
2876 class VerifyObjsInRegionClosure: public ObjectClosure {
2877 private:
2878 G1CollectedHeap* _g1h;
2879 size_t _live_bytes;
2880 HeapRegion *_hr;
2881 VerifyOption _vo;
2882 public:
2883 // _vo == UsePrevMarking -> use "prev" marking information,
2884 // _vo == UseNextMarking -> use "next" marking information,
2885 // _vo == UseMarkWord -> use mark word from object header.
2886 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2887 : _live_bytes(0), _hr(hr), _vo(vo) {
2888 _g1h = G1CollectedHeap::heap();
2889 }
2890 void do_object(oop o) {
2891 VerifyLivenessOopClosure isLive(_g1h, _vo);
2892 assert(o != NULL, "Huh?");
2893 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2894 // If the object is alive according to the mark word,
2895 // then verify that the marking information agrees.
2896 // Note we can't verify the contra-positive of the
2897 // above: if the object is dead (according to the mark
2898 // word), it may not be marked, or may have been marked
2899 // but has since became dead, or may have been allocated
2900 // since the last marking.
2901 if (_vo == VerifyOption_G1UseMarkWord) {
2902 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2903 }
2904
2905 o->oop_iterate_no_header(&isLive);
2906 if (!_hr->obj_allocated_since_prev_marking(o)) {
2907 size_t obj_size = o->size(); // Make sure we don't overflow
2908 _live_bytes += (obj_size * HeapWordSize);
2909 }
2910 }
2911 }
2912 size_t live_bytes() { return _live_bytes; }
2913 };
2914
2915 class VerifyArchiveOopClosure: public OopClosure {
2916 public:
2917 VerifyArchiveOopClosure(HeapRegion *hr) { }
2918 void do_oop(narrowOop *p) { do_oop_work(p); }
2919 void do_oop( oop *p) { do_oop_work(p); }
2920
2921 template <class T> void do_oop_work(T *p) {
2922 oop obj = oopDesc::load_decode_heap_oop(p);
2923 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2924 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2925 p2i(p), p2i(obj));
2926 }
2927 };
2928
2929 class VerifyArchiveRegionClosure: public ObjectClosure {
2930 public:
2931 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2932 // Verify that all object pointers are to archive regions.
2933 void do_object(oop o) {
2934 VerifyArchiveOopClosure checkOop(NULL);
2935 assert(o != NULL, "Should not be here for NULL oops");
2936 o->oop_iterate_no_header(&checkOop);
2937 }
2938 };
2939
2940 class VerifyRegionClosure: public HeapRegionClosure {
2941 private:
2942 bool _par;
2943 VerifyOption _vo;
2944 bool _failures;
2945 public:
2946 // _vo == UsePrevMarking -> use "prev" marking information,
2947 // _vo == UseNextMarking -> use "next" marking information,
2948 // _vo == UseMarkWord -> use mark word from object header.
2949 VerifyRegionClosure(bool par, VerifyOption vo)
2950 : _par(par),
2951 _vo(vo),
2952 _failures(false) {}
2953
2954 bool failures() {
2955 return _failures;
2956 }
2957
2958 bool doHeapRegion(HeapRegion* r) {
2959 // For archive regions, verify there are no heap pointers to
2960 // non-pinned regions. For all others, verify liveness info.
2961 if (r->is_archive()) {
2962 VerifyArchiveRegionClosure verify_oop_pointers(r);
2963 r->object_iterate(&verify_oop_pointers);
2964 return true;
2965 }
2966 if (!r->is_continues_humongous()) {
2967 bool failures = false;
2968 r->verify(_vo, &failures);
2969 if (failures) {
2970 _failures = true;
2971 } else if (!r->is_starts_humongous()) {
2972 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2973 r->object_iterate(¬_dead_yet_cl);
2974 if (_vo != VerifyOption_G1UseNextMarking) {
2975 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2976 log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2977 p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2978 _failures = true;
2979 }
2980 } else {
2981 // When vo == UseNextMarking we cannot currently do a sanity
2982 // check on the live bytes as the calculation has not been
2983 // finalized yet.
2984 }
2985 }
2986 }
2987 return false; // stop the region iteration if we hit a failure
2988 }
2989 };
2990
2991 // This is the task used for parallel verification of the heap regions
2992
2993 class G1ParVerifyTask: public AbstractGangTask {
2994 private:
2995 G1CollectedHeap* _g1h;
2996 VerifyOption _vo;
2997 bool _failures;
2998 HeapRegionClaimer _hrclaimer;
2999
3000 public:
3001 // _vo == UsePrevMarking -> use "prev" marking information,
3002 // _vo == UseNextMarking -> use "next" marking information,
3003 // _vo == UseMarkWord -> use mark word from object header.
3004 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3005 AbstractGangTask("Parallel verify task"),
3006 _g1h(g1h),
3007 _vo(vo),
3008 _failures(false),
3009 _hrclaimer(g1h->workers()->active_workers()) {}
3010
3011 bool failures() {
3012 return _failures;
3013 }
3014
3015 void work(uint worker_id) {
3016 HandleMark hm;
3017 VerifyRegionClosure blk(true, _vo);
3018 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3019 if (blk.failures()) {
3020 _failures = true;
3021 }
3022 }
3023 };
3024
3025 void G1CollectedHeap::verify(VerifyOption vo) {
3026 if (!SafepointSynchronize::is_at_safepoint()) {
3027 log_info(gc, verify)("Skipping verification. Not at safepoint.");
3028 }
3029
3030 assert(Thread::current()->is_VM_thread(),
3031 "Expected to be executed serially by the VM thread at this point");
3032
3033 log_debug(gc, verify)("Roots");
3034 VerifyRootsClosure rootsCl(vo);
3035 VerifyKlassClosure klassCl(this, &rootsCl);
3036 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3037
3038 // We apply the relevant closures to all the oops in the
3039 // system dictionary, class loader data graph, the string table
3040 // and the nmethods in the code cache.
3041 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3042 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3043
3044 {
3045 G1RootProcessor root_processor(this, 1);
3046 root_processor.process_all_roots(&rootsCl,
3047 &cldCl,
3048 &blobsCl);
3049 }
3050
3051 bool failures = rootsCl.failures() || codeRootsCl.failures();
3052
3053 if (vo != VerifyOption_G1UseMarkWord) {
3054 // If we're verifying during a full GC then the region sets
3055 // will have been torn down at the start of the GC. Therefore
3056 // verifying the region sets will fail. So we only verify
3057 // the region sets when not in a full GC.
3058 log_debug(gc, verify)("HeapRegionSets");
3059 verify_region_sets();
3060 }
3061
3062 log_debug(gc, verify)("HeapRegions");
3063 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3064
3065 G1ParVerifyTask task(this, vo);
3066 workers()->run_task(&task);
3067 if (task.failures()) {
3068 failures = true;
3069 }
3070
3071 } else {
3072 VerifyRegionClosure blk(false, vo);
3073 heap_region_iterate(&blk);
3074 if (blk.failures()) {
3075 failures = true;
3076 }
3077 }
3078
3079 if (G1StringDedup::is_enabled()) {
3080 log_debug(gc, verify)("StrDedup");
3081 G1StringDedup::verify();
3082 }
3083
3084 if (failures) {
3085 log_info(gc, verify)("Heap after failed verification:");
3086 // It helps to have the per-region information in the output to
3087 // help us track down what went wrong. This is why we call
3088 // print_extended_on() instead of print_on().
3089 LogHandle(gc, verify) log;
3090 ResourceMark rm;
3091 print_extended_on(log.info_stream());
3092 }
3093 guarantee(!failures, "there should not have been any failures");
3094 }
3095
3096 double G1CollectedHeap::verify(bool guard, const char* msg) {
3097 double verify_time_ms = 0.0;
3098
3099 if (guard && total_collections() >= VerifyGCStartAt) {
3100 double verify_start = os::elapsedTime();
3101 HandleMark hm; // Discard invalid handles created during verification
3102 prepare_for_verify();
3103 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3104 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3105 }
3106
3107 return verify_time_ms;
3108 }
3109
3110 void G1CollectedHeap::verify_before_gc() {
3111 double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3112 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3113 }
3114
3115 void G1CollectedHeap::verify_after_gc() {
3116 double verify_time_ms = verify(VerifyAfterGC, "After GC");
3117 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3118 }
3119
3120 class PrintRegionClosure: public HeapRegionClosure {
3121 outputStream* _st;
3122 public:
3123 PrintRegionClosure(outputStream* st) : _st(st) {}
3124 bool doHeapRegion(HeapRegion* r) {
3125 r->print_on(_st);
3126 return false;
3127 }
3128 };
3129
3130 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3131 const HeapRegion* hr,
3132 const VerifyOption vo) const {
3133 switch (vo) {
3134 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3135 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3136 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3137 default: ShouldNotReachHere();
3138 }
3139 return false; // keep some compilers happy
3140 }
3141
3142 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3143 const VerifyOption vo) const {
3144 switch (vo) {
3145 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3146 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3147 case VerifyOption_G1UseMarkWord: {
3148 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3149 return !obj->is_gc_marked() && !hr->is_archive();
3150 }
3151 default: ShouldNotReachHere();
3152 }
3153 return false; // keep some compilers happy
3154 }
3155
3156 void G1CollectedHeap::print_on(outputStream* st) const {
3157 st->print(" %-20s", "garbage-first heap");
3158 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3159 capacity()/K, used_unlocked()/K);
3160 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3161 p2i(_hrm.reserved().start()),
3162 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3163 p2i(_hrm.reserved().end()));
3164 st->cr();
3165 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3166 uint young_regions = _young_list->length();
3167 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3168 (size_t) young_regions * HeapRegion::GrainBytes / K);
3169 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3170 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3171 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3172 st->cr();
3173 MetaspaceAux::print_on(st);
3174 }
3175
3176 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3177 print_on(st);
3178
3179 // Print the per-region information.
3180 st->cr();
3181 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
3182 "HS=humongous(starts), HC=humongous(continues), "
3183 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3184 "AC=allocation context, "
3185 "TAMS=top-at-mark-start (previous, next)");
3186 PrintRegionClosure blk(st);
3187 heap_region_iterate(&blk);
3188 }
3189
3190 void G1CollectedHeap::print_on_error(outputStream* st) const {
3191 this->CollectedHeap::print_on_error(st);
3192
3193 if (_cm != NULL) {
3194 st->cr();
3195 _cm->print_on_error(st);
3196 }
3197 }
3198
3199 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3200 workers()->print_worker_threads_on(st);
3201 _cmThread->print_on(st);
3202 st->cr();
3203 _cm->print_worker_threads_on(st);
3204 _cg1r->print_worker_threads_on(st);
3205 if (G1StringDedup::is_enabled()) {
3206 G1StringDedup::print_worker_threads_on(st);
3207 }
3208 }
3209
3210 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3211 workers()->threads_do(tc);
3212 tc->do_thread(_cmThread);
3213 _cg1r->threads_do(tc);
3214 if (G1StringDedup::is_enabled()) {
3215 G1StringDedup::threads_do(tc);
3216 }
3217 }
3218
3219 void G1CollectedHeap::print_tracing_info() const {
3220 // We'll overload this to mean "trace GC pause statistics."
3221 if (TraceYoungGenTime || TraceOldGenTime) {
3222 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3223 // to that.
3224 g1_policy()->print_tracing_info();
3225 }
3226 g1_rem_set()->print_summary_info();
3227 concurrent_mark()->print_summary_info();
3228 g1_policy()->print_yg_surv_rate_info();
3229 }
3230
3231 #ifndef PRODUCT
3232 // Helpful for debugging RSet issues.
3233
3234 class PrintRSetsClosure : public HeapRegionClosure {
3235 private:
3236 const char* _msg;
3237 size_t _occupied_sum;
3238
3239 public:
3240 bool doHeapRegion(HeapRegion* r) {
3241 HeapRegionRemSet* hrrs = r->rem_set();
3242 size_t occupied = hrrs->occupied();
3243 _occupied_sum += occupied;
3244
3245 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
3246 if (occupied == 0) {
3247 tty->print_cr(" RSet is empty");
3248 } else {
3249 hrrs->print();
3250 }
3251 tty->print_cr("----------");
3252 return false;
3253 }
3254
3255 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3256 tty->cr();
3257 tty->print_cr("========================================");
3258 tty->print_cr("%s", msg);
3259 tty->cr();
3260 }
3261
3262 ~PrintRSetsClosure() {
3263 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3264 tty->print_cr("========================================");
3265 tty->cr();
3266 }
3267 };
3268
3269 void G1CollectedHeap::print_cset_rsets() {
3270 PrintRSetsClosure cl("Printing CSet RSets");
3271 collection_set_iterate(&cl);
3272 }
3273
3274 void G1CollectedHeap::print_all_rsets() {
3275 PrintRSetsClosure cl("Printing All RSets");;
3276 heap_region_iterate(&cl);
3277 }
3278 #endif // PRODUCT
3279
3280 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3281 YoungList* young_list = heap()->young_list();
3282
3283 size_t eden_used_bytes = young_list->eden_used_bytes();
3284 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3285
3286 size_t eden_capacity_bytes =
3287 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3288
3289 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3290 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3291 }
3292
3293 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3294 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3295 stats->unused(), stats->used(), stats->region_end_waste(),
3296 stats->regions_filled(), stats->direct_allocated(),
3297 stats->failure_used(), stats->failure_waste());
3298 }
3299
3300 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3301 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3302 gc_tracer->report_gc_heap_summary(when, heap_summary);
3303
3304 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3305 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3306 }
3307
3308
3309 G1CollectedHeap* G1CollectedHeap::heap() {
3310 CollectedHeap* heap = Universe::heap();
3311 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3312 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3313 return (G1CollectedHeap*)heap;
3314 }
3315
3316 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3317 // always_do_update_barrier = false;
3318 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3319 // Fill TLAB's and such
3320 accumulate_statistics_all_tlabs();
3321 ensure_parsability(true);
3322
3323 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3324 }
3325
3326 void G1CollectedHeap::gc_epilogue(bool full) {
3327 // we are at the end of the GC. Total collections has already been increased.
3328 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3329
3330 // FIXME: what is this about?
3331 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3332 // is set.
3333 #if defined(COMPILER2) || INCLUDE_JVMCI
3334 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3335 #endif
3336 // always_do_update_barrier = true;
3337
3338 resize_all_tlabs();
3339 allocation_context_stats().update(full);
3340
3341 // We have just completed a GC. Update the soft reference
3342 // policy with the new heap occupancy
3343 Universe::update_heap_info_at_gc();
3344 }
3345
3346 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3347 uint gc_count_before,
3348 bool* succeeded,
3349 GCCause::Cause gc_cause) {
3350 assert_heap_not_locked_and_not_at_safepoint();
3351 g1_policy()->record_stop_world_start();
3352 VM_G1IncCollectionPause op(gc_count_before,
3353 word_size,
3354 false, /* should_initiate_conc_mark */
3355 g1_policy()->max_pause_time_ms(),
3356 gc_cause);
3357
3358 op.set_allocation_context(AllocationContext::current());
3359 VMThread::execute(&op);
3360
3361 HeapWord* result = op.result();
3362 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3363 assert(result == NULL || ret_succeeded,
3364 "the result should be NULL if the VM did not succeed");
3365 *succeeded = ret_succeeded;
3366
3367 assert_heap_not_locked();
3368 return result;
3369 }
3370
3371 void
3372 G1CollectedHeap::doConcurrentMark() {
3373 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3374 if (!_cmThread->in_progress()) {
3375 _cmThread->set_started();
3376 CGC_lock->notify();
3377 }
3378 }
3379
3380 size_t G1CollectedHeap::pending_card_num() {
3381 size_t extra_cards = 0;
3382 JavaThread *curr = Threads::first();
3383 while (curr != NULL) {
3384 DirtyCardQueue& dcq = curr->dirty_card_queue();
3385 extra_cards += dcq.size();
3386 curr = curr->next();
3387 }
3388 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3389 size_t buffer_size = dcqs.buffer_size();
3390 size_t buffer_num = dcqs.completed_buffers_num();
3391
3392 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3393 // in bytes - not the number of 'entries'. We need to convert
3394 // into a number of cards.
3395 return (buffer_size * buffer_num + extra_cards) / oopSize;
3396 }
3397
3398 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3399 private:
3400 size_t _total_humongous;
3401 size_t _candidate_humongous;
3402
3403 DirtyCardQueue _dcq;
3404
3405 // We don't nominate objects with many remembered set entries, on
3406 // the assumption that such objects are likely still live.
3407 bool is_remset_small(HeapRegion* region) const {
3408 HeapRegionRemSet* const rset = region->rem_set();
3409 return G1EagerReclaimHumongousObjectsWithStaleRefs
3410 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3411 : rset->is_empty();
3412 }
3413
3414 bool is_typeArray_region(HeapRegion* region) const {
3415 return oop(region->bottom())->is_typeArray();
3416 }
3417
3418 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3419 assert(region->is_starts_humongous(), "Must start a humongous object");
3420
3421 // Candidate selection must satisfy the following constraints
3422 // while concurrent marking is in progress:
3423 //
3424 // * In order to maintain SATB invariants, an object must not be
3425 // reclaimed if it was allocated before the start of marking and
3426 // has not had its references scanned. Such an object must have
3427 // its references (including type metadata) scanned to ensure no
3428 // live objects are missed by the marking process. Objects
3429 // allocated after the start of concurrent marking don't need to
3430 // be scanned.
3431 //
3432 // * An object must not be reclaimed if it is on the concurrent
3433 // mark stack. Objects allocated after the start of concurrent
3434 // marking are never pushed on the mark stack.
3435 //
3436 // Nominating only objects allocated after the start of concurrent
3437 // marking is sufficient to meet both constraints. This may miss
3438 // some objects that satisfy the constraints, but the marking data
3439 // structures don't support efficiently performing the needed
3440 // additional tests or scrubbing of the mark stack.
3441 //
3442 // However, we presently only nominate is_typeArray() objects.
3443 // A humongous object containing references induces remembered
3444 // set entries on other regions. In order to reclaim such an
3445 // object, those remembered sets would need to be cleaned up.
3446 //
3447 // We also treat is_typeArray() objects specially, allowing them
3448 // to be reclaimed even if allocated before the start of
3449 // concurrent mark. For this we rely on mark stack insertion to
3450 // exclude is_typeArray() objects, preventing reclaiming an object
3451 // that is in the mark stack. We also rely on the metadata for
3452 // such objects to be built-in and so ensured to be kept live.
3453 // Frequent allocation and drop of large binary blobs is an
3454 // important use case for eager reclaim, and this special handling
3455 // may reduce needed headroom.
3456
3457 return is_typeArray_region(region) && is_remset_small(region);
3458 }
3459
3460 public:
3461 RegisterHumongousWithInCSetFastTestClosure()
3462 : _total_humongous(0),
3463 _candidate_humongous(0),
3464 _dcq(&JavaThread::dirty_card_queue_set()) {
3465 }
3466
3467 virtual bool doHeapRegion(HeapRegion* r) {
3468 if (!r->is_starts_humongous()) {
3469 return false;
3470 }
3471 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3472
3473 bool is_candidate = humongous_region_is_candidate(g1h, r);
3474 uint rindex = r->hrm_index();
3475 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3476 if (is_candidate) {
3477 _candidate_humongous++;
3478 g1h->register_humongous_region_with_cset(rindex);
3479 // Is_candidate already filters out humongous object with large remembered sets.
3480 // If we have a humongous object with a few remembered sets, we simply flush these
3481 // remembered set entries into the DCQS. That will result in automatic
3482 // re-evaluation of their remembered set entries during the following evacuation
3483 // phase.
3484 if (!r->rem_set()->is_empty()) {
3485 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3486 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3487 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3488 HeapRegionRemSetIterator hrrs(r->rem_set());
3489 size_t card_index;
3490 while (hrrs.has_next(card_index)) {
3491 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3492 // The remembered set might contain references to already freed
3493 // regions. Filter out such entries to avoid failing card table
3494 // verification.
3495 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3496 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3497 *card_ptr = CardTableModRefBS::dirty_card_val();
3498 _dcq.enqueue(card_ptr);
3499 }
3500 }
3501 }
3502 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3503 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3504 hrrs.n_yielded(), r->rem_set()->occupied());
3505 r->rem_set()->clear_locked();
3506 }
3507 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3508 }
3509 _total_humongous++;
3510
3511 return false;
3512 }
3513
3514 size_t total_humongous() const { return _total_humongous; }
3515 size_t candidate_humongous() const { return _candidate_humongous; }
3516
3517 void flush_rem_set_entries() { _dcq.flush(); }
3518 };
3519
3520 void G1CollectedHeap::register_humongous_regions_with_cset() {
3521 if (!G1EagerReclaimHumongousObjects) {
3522 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3523 return;
3524 }
3525 double time = os::elapsed_counter();
3526
3527 // Collect reclaim candidate information and register candidates with cset.
3528 RegisterHumongousWithInCSetFastTestClosure cl;
3529 heap_region_iterate(&cl);
3530
3531 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3532 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3533 cl.total_humongous(),
3534 cl.candidate_humongous());
3535 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3536
3537 // Finally flush all remembered set entries to re-check into the global DCQS.
3538 cl.flush_rem_set_entries();
3539 }
3540
3541 #ifdef ASSERT
3542 class VerifyCSetClosure: public HeapRegionClosure {
3543 public:
3544 bool doHeapRegion(HeapRegion* hr) {
3545 // Here we check that the CSet region's RSet is ready for parallel
3546 // iteration. The fields that we'll verify are only manipulated
3547 // when the region is part of a CSet and is collected. Afterwards,
3548 // we reset these fields when we clear the region's RSet (when the
3549 // region is freed) so they are ready when the region is
3550 // re-allocated. The only exception to this is if there's an
3551 // evacuation failure and instead of freeing the region we leave
3552 // it in the heap. In that case, we reset these fields during
3553 // evacuation failure handling.
3554 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3555
3556 // Here's a good place to add any other checks we'd like to
3557 // perform on CSet regions.
3558 return false;
3559 }
3560 };
3561 #endif // ASSERT
3562
3563 uint G1CollectedHeap::num_task_queues() const {
3564 return _task_queues->size();
3565 }
3566
3567 #if TASKQUEUE_STATS
3568 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3569 st->print_raw_cr("GC Task Stats");
3570 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3571 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3572 }
3573
3574 void G1CollectedHeap::print_taskqueue_stats() const {
3575 if (!develop_log_is_enabled(Trace, gc, task, stats)) {
3576 return;
3577 }
3578 LogHandle(gc, task, stats) log;
3579 ResourceMark rm;
3580 outputStream* st = log.trace_stream();
3581
3582 print_taskqueue_stats_hdr(st);
3583
3584 TaskQueueStats totals;
3585 const uint n = num_task_queues();
3586 for (uint i = 0; i < n; ++i) {
3587 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3588 totals += task_queue(i)->stats;
3589 }
3590 st->print_raw("tot "); totals.print(st); st->cr();
3591
3592 DEBUG_ONLY(totals.verify());
3593 }
3594
3595 void G1CollectedHeap::reset_taskqueue_stats() {
3596 const uint n = num_task_queues();
3597 for (uint i = 0; i < n; ++i) {
3598 task_queue(i)->stats.reset();
3599 }
3600 }
3601 #endif // TASKQUEUE_STATS
3602
3603 void G1CollectedHeap::log_gc_footer(double pause_time_counter) {
3604 if (evacuation_failed()) {
3605 log_info(gc)("To-space exhausted");
3606 }
3607
3608 double pause_time_sec = TimeHelper::counter_to_seconds(pause_time_counter);
3609 g1_policy()->print_phases(pause_time_sec);
3610
3611 g1_policy()->print_detailed_heap_transition();
3612 }
3613
3614
3615 void G1CollectedHeap::wait_for_root_region_scanning() {
3616 double scan_wait_start = os::elapsedTime();
3617 // We have to wait until the CM threads finish scanning the
3618 // root regions as it's the only way to ensure that all the
3619 // objects on them have been correctly scanned before we start
3620 // moving them during the GC.
3621 bool waited = _cm->root_regions()->wait_until_scan_finished();
3622 double wait_time_ms = 0.0;
3623 if (waited) {
3624 double scan_wait_end = os::elapsedTime();
3625 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3626 }
3627 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3628 }
3629
3630 bool
3631 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3632 assert_at_safepoint(true /* should_be_vm_thread */);
3633 guarantee(!is_gc_active(), "collection is not reentrant");
3634
3635 if (GC_locker::check_active_before_gc()) {
3636 return false;
3637 }
3638
3639 _gc_timer_stw->register_gc_start();
3640
3641 GCIdMark gc_id_mark;
3642 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3643
3644 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3645 ResourceMark rm;
3646
3647 wait_for_root_region_scanning();
3648
3649 print_heap_before_gc();
3650 trace_heap_before_gc(_gc_tracer_stw);
3651
3652 verify_region_sets_optional();
3653 verify_dirty_young_regions();
3654
3655 // This call will decide whether this pause is an initial-mark
3656 // pause. If it is, during_initial_mark_pause() will return true
3657 // for the duration of this pause.
3658 g1_policy()->decide_on_conc_mark_initiation();
3659
3660 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3661 assert(!collector_state()->during_initial_mark_pause() ||
3662 collector_state()->gcs_are_young(), "sanity");
3663
3664 // We also do not allow mixed GCs during marking.
3665 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3666
3667 // Record whether this pause is an initial mark. When the current
3668 // thread has completed its logging output and it's safe to signal
3669 // the CM thread, the flag's value in the policy has been reset.
3670 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3671
3672 // Inner scope for scope based logging, timers, and stats collection
3673 {
3674 EvacuationInfo evacuation_info;
3675
3676 if (collector_state()->during_initial_mark_pause()) {
3677 // We are about to start a marking cycle, so we increment the
3678 // full collection counter.
3679 increment_old_marking_cycles_started();
3680 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3681 }
3682
3683 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3684
3685 GCTraceCPUTime tcpu;
3686
3687 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3688 workers()->active_workers(),
3689 Threads::number_of_non_daemon_threads());
3690 workers()->set_active_workers(active_workers);
3691 FormatBuffer<> gc_string("Pause ");
3692 if (collector_state()->during_initial_mark_pause()) {
3693 gc_string.append("Initial Mark");
3694 } else if (collector_state()->gcs_are_young()) {
3695 gc_string.append("Young");
3696 } else {
3697 gc_string.append("Mixed");
3698 }
3699 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3700
3701 double pause_start_sec = os::elapsedTime();
3702 double pause_start_counter = os::elapsed_counter();
3703 g1_policy()->note_gc_start(active_workers);
3704
3705 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3706 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3707
3708 // If the secondary_free_list is not empty, append it to the
3709 // free_list. No need to wait for the cleanup operation to finish;
3710 // the region allocation code will check the secondary_free_list
3711 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3712 // set, skip this step so that the region allocation code has to
3713 // get entries from the secondary_free_list.
3714 if (!G1StressConcRegionFreeing) {
3715 append_secondary_free_list_if_not_empty_with_lock();
3716 }
3717
3718 assert(check_young_list_well_formed(), "young list should be well formed");
3719
3720 // Don't dynamically change the number of GC threads this early. A value of
3721 // 0 is used to indicate serial work. When parallel work is done,
3722 // it will be set.
3723
3724 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3725 IsGCActiveMark x;
3726
3727 gc_prologue(false);
3728 increment_total_collections(false /* full gc */);
3729 increment_gc_time_stamp();
3730
3731 verify_before_gc();
3732
3733 check_bitmaps("GC Start");
3734
3735 #if defined(COMPILER2) || INCLUDE_JVMCI
3736 DerivedPointerTable::clear();
3737 #endif
3738
3739 // Please see comment in g1CollectedHeap.hpp and
3740 // G1CollectedHeap::ref_processing_init() to see how
3741 // reference processing currently works in G1.
3742
3743 // Enable discovery in the STW reference processor
3744 if (g1_policy()->should_process_references()) {
3745 ref_processor_stw()->enable_discovery();
3746 } else {
3747 ref_processor_stw()->disable_discovery();
3748 }
3749
3750 {
3751 // We want to temporarily turn off discovery by the
3752 // CM ref processor, if necessary, and turn it back on
3753 // on again later if we do. Using a scoped
3754 // NoRefDiscovery object will do this.
3755 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3756
3757 // Forget the current alloc region (we might even choose it to be part
3758 // of the collection set!).
3759 _allocator->release_mutator_alloc_region();
3760
3761 // This timing is only used by the ergonomics to handle our pause target.
3762 // It is unclear why this should not include the full pause. We will
3763 // investigate this in CR 7178365.
3764 //
3765 // Preserving the old comment here if that helps the investigation:
3766 //
3767 // The elapsed time induced by the start time below deliberately elides
3768 // the possible verification above.
3769 double sample_start_time_sec = os::elapsedTime();
3770
3771 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3772
3773 if (collector_state()->during_initial_mark_pause()) {
3774 concurrent_mark()->checkpointRootsInitialPre();
3775 }
3776
3777 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3778 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3779
3780 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3781
3782 // Make sure the remembered sets are up to date. This needs to be
3783 // done before register_humongous_regions_with_cset(), because the
3784 // remembered sets are used there to choose eager reclaim candidates.
3785 // If the remembered sets are not up to date we might miss some
3786 // entries that need to be handled.
3787 g1_rem_set()->cleanupHRRS();
3788
3789 register_humongous_regions_with_cset();
3790
3791 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3792
3793 _cm->note_start_of_gc();
3794 // We call this after finalize_cset() to
3795 // ensure that the CSet has been finalized.
3796 _cm->verify_no_cset_oops();
3797
3798 if (_hr_printer.is_active()) {
3799 HeapRegion* hr = g1_policy()->collection_set();
3800 while (hr != NULL) {
3801 _hr_printer.cset(hr);
3802 hr = hr->next_in_collection_set();
3803 }
3804 }
3805
3806 #ifdef ASSERT
3807 VerifyCSetClosure cl;
3808 collection_set_iterate(&cl);
3809 #endif // ASSERT
3810
3811 // Initialize the GC alloc regions.
3812 _allocator->init_gc_alloc_regions(evacuation_info);
3813
3814 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3815 pre_evacuate_collection_set();
3816
3817 // Actually do the work...
3818 evacuate_collection_set(evacuation_info, &per_thread_states);
3819
3820 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3821
3822 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3823 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3824
3825 eagerly_reclaim_humongous_regions();
3826
3827 g1_policy()->clear_collection_set();
3828
3829 // Start a new incremental collection set for the next pause.
3830 g1_policy()->start_incremental_cset_building();
3831
3832 clear_cset_fast_test();
3833
3834 _young_list->reset_sampled_info();
3835
3836 // Don't check the whole heap at this point as the
3837 // GC alloc regions from this pause have been tagged
3838 // as survivors and moved on to the survivor list.
3839 // Survivor regions will fail the !is_young() check.
3840 assert(check_young_list_empty(false /* check_heap */),
3841 "young list should be empty");
3842
3843 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3844 _young_list->first_survivor_region(),
3845 _young_list->last_survivor_region());
3846
3847 _young_list->reset_auxilary_lists();
3848
3849 if (evacuation_failed()) {
3850 set_used(recalculate_used());
3851 if (_archive_allocator != NULL) {
3852 _archive_allocator->clear_used();
3853 }
3854 for (uint i = 0; i < ParallelGCThreads; i++) {
3855 if (_evacuation_failed_info_array[i].has_failed()) {
3856 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3857 }
3858 }
3859 } else {
3860 // The "used" of the the collection set have already been subtracted
3861 // when they were freed. Add in the bytes evacuated.
3862 increase_used(g1_policy()->bytes_copied_during_gc());
3863 }
3864
3865 if (collector_state()->during_initial_mark_pause()) {
3866 // We have to do this before we notify the CM threads that
3867 // they can start working to make sure that all the
3868 // appropriate initialization is done on the CM object.
3869 concurrent_mark()->checkpointRootsInitialPost();
3870 collector_state()->set_mark_in_progress(true);
3871 // Note that we don't actually trigger the CM thread at
3872 // this point. We do that later when we're sure that
3873 // the current thread has completed its logging output.
3874 }
3875
3876 allocate_dummy_regions();
3877
3878 _allocator->init_mutator_alloc_region();
3879
3880 {
3881 size_t expand_bytes = g1_policy()->expansion_amount();
3882 if (expand_bytes > 0) {
3883 size_t bytes_before = capacity();
3884 // No need for an ergo logging here,
3885 // expansion_amount() does this when it returns a value > 0.
3886 double expand_ms;
3887 if (!expand(expand_bytes, &expand_ms)) {
3888 // We failed to expand the heap. Cannot do anything about it.
3889 }
3890 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3891 }
3892 }
3893
3894 // We redo the verification but now wrt to the new CSet which
3895 // has just got initialized after the previous CSet was freed.
3896 _cm->verify_no_cset_oops();
3897 _cm->note_end_of_gc();
3898
3899 // This timing is only used by the ergonomics to handle our pause target.
3900 // It is unclear why this should not include the full pause. We will
3901 // investigate this in CR 7178365.
3902 double sample_end_time_sec = os::elapsedTime();
3903 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3904 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3905 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3906
3907 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3908 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3909
3910 MemoryService::track_memory_usage();
3911
3912 // In prepare_for_verify() below we'll need to scan the deferred
3913 // update buffers to bring the RSets up-to-date if
3914 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3915 // the update buffers we'll probably need to scan cards on the
3916 // regions we just allocated to (i.e., the GC alloc
3917 // regions). However, during the last GC we called
3918 // set_saved_mark() on all the GC alloc regions, so card
3919 // scanning might skip the [saved_mark_word()...top()] area of
3920 // those regions (i.e., the area we allocated objects into
3921 // during the last GC). But it shouldn't. Given that
3922 // saved_mark_word() is conditional on whether the GC time stamp
3923 // on the region is current or not, by incrementing the GC time
3924 // stamp here we invalidate all the GC time stamps on all the
3925 // regions and saved_mark_word() will simply return top() for
3926 // all the regions. This is a nicer way of ensuring this rather
3927 // than iterating over the regions and fixing them. In fact, the
3928 // GC time stamp increment here also ensures that
3929 // saved_mark_word() will return top() between pauses, i.e.,
3930 // during concurrent refinement. So we don't need the
3931 // is_gc_active() check to decided which top to use when
3932 // scanning cards (see CR 7039627).
3933 increment_gc_time_stamp();
3934
3935 verify_after_gc();
3936 check_bitmaps("GC End");
3937
3938 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3939 ref_processor_stw()->verify_no_references_recorded();
3940
3941 // CM reference discovery will be re-enabled if necessary.
3942 }
3943
3944 #ifdef TRACESPINNING
3945 ParallelTaskTerminator::print_termination_counts();
3946 #endif
3947
3948 gc_epilogue(false);
3949 }
3950
3951 // Print the remainder of the GC log output.
3952 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3953
3954 // It is not yet to safe to tell the concurrent mark to
3955 // start as we have some optional output below. We don't want the
3956 // output from the concurrent mark thread interfering with this
3957 // logging output either.
3958
3959 _hrm.verify_optional();
3960 verify_region_sets_optional();
3961
3962 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3963 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3964
3965 print_heap_after_gc();
3966 trace_heap_after_gc(_gc_tracer_stw);
3967
3968 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3969 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3970 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3971 // before any GC notifications are raised.
3972 g1mm()->update_sizes();
3973
3974 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3975 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3976 _gc_timer_stw->register_gc_end();
3977 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3978 }
3979 // It should now be safe to tell the concurrent mark thread to start
3980 // without its logging output interfering with the logging output
3981 // that came from the pause.
3982
3983 if (should_start_conc_mark) {
3984 // CAUTION: after the doConcurrentMark() call below,
3985 // the concurrent marking thread(s) could be running
3986 // concurrently with us. Make sure that anything after
3987 // this point does not assume that we are the only GC thread
3988 // running. Note: of course, the actual marking work will
3989 // not start until the safepoint itself is released in
3990 // SuspendibleThreadSet::desynchronize().
3991 doConcurrentMark();
3992 }
3993
3994 return true;
3995 }
3996
3997 void G1CollectedHeap::restore_preserved_marks() {
3998 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3999 workers()->run_task(&rpm_task);
4000 }
4001
4002 void G1CollectedHeap::remove_self_forwarding_pointers() {
4003 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4004 workers()->run_task(&rsfp_task);
4005 }
4006
4007 void G1CollectedHeap::restore_after_evac_failure() {
4008 double remove_self_forwards_start = os::elapsedTime();
4009
4010 remove_self_forwarding_pointers();
4011 restore_preserved_marks();
4012
4013 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4014 }
4015
4016 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4017 if (!_evacuation_failed) {
4018 _evacuation_failed = true;
4019 }
4020
4021 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4022
4023 // We want to call the "for_promotion_failure" version only in the
4024 // case of a promotion failure.
4025 if (m->must_be_preserved_for_promotion_failure(obj)) {
4026 OopAndMarkOop elem(obj, m);
4027 _preserved_objs[worker_id].push(elem);
4028 }
4029 }
4030
4031 bool G1ParEvacuateFollowersClosure::offer_termination() {
4032 G1ParScanThreadState* const pss = par_scan_state();
4033 start_term_time();
4034 const bool res = terminator()->offer_termination();
4035 end_term_time();
4036 return res;
4037 }
4038
4039 void G1ParEvacuateFollowersClosure::do_void() {
4040 G1ParScanThreadState* const pss = par_scan_state();
4041 pss->trim_queue();
4042 do {
4043 pss->steal_and_trim_queue(queues());
4044 } while (!offer_termination());
4045 }
4046
4047 class G1ParTask : public AbstractGangTask {
4048 protected:
4049 G1CollectedHeap* _g1h;
4050 G1ParScanThreadStateSet* _pss;
4051 RefToScanQueueSet* _queues;
4052 G1RootProcessor* _root_processor;
4053 ParallelTaskTerminator _terminator;
4054 uint _n_workers;
4055
4056 public:
4057 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4058 : AbstractGangTask("G1 collection"),
4059 _g1h(g1h),
4060 _pss(per_thread_states),
4061 _queues(task_queues),
4062 _root_processor(root_processor),
4063 _terminator(n_workers, _queues),
4064 _n_workers(n_workers)
4065 {}
4066
4067 void work(uint worker_id) {
4068 if (worker_id >= _n_workers) return; // no work needed this round
4069
4070 double start_sec = os::elapsedTime();
4071 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4072
4073 {
4074 ResourceMark rm;
4075 HandleMark hm;
4076
4077 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4078
4079 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4080 pss->set_ref_processor(rp);
4081
4082 double start_strong_roots_sec = os::elapsedTime();
4083
4084 _root_processor->evacuate_roots(pss->closures(), worker_id);
4085
4086 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4087
4088 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4089 // treating the nmethods visited to act as roots for concurrent marking.
4090 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4091 // objects copied by the current evacuation.
4092 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4093 pss->closures()->weak_codeblobs(),
4094 worker_id);
4095
4096 _pss->add_cards_scanned(worker_id, cards_scanned);
4097
4098 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4099
4100 double term_sec = 0.0;
4101 size_t evac_term_attempts = 0;
4102 {
4103 double start = os::elapsedTime();
4104 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4105 evac.do_void();
4106
4107 evac_term_attempts = evac.term_attempts();
4108 term_sec = evac.term_time();
4109 double elapsed_sec = os::elapsedTime() - start;
4110 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4111 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4112 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4113 }
4114
4115 assert(pss->queue_is_empty(), "should be empty");
4116
4117 if (log_is_enabled(Debug, gc, task, stats)) {
4118 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4119 size_t lab_waste;
4120 size_t lab_undo_waste;
4121 pss->waste(lab_waste, lab_undo_waste);
4122 _g1h->print_termination_stats(worker_id,
4123 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4124 strong_roots_sec * 1000.0, /* strong roots time */
4125 term_sec * 1000.0, /* evac term time */
4126 evac_term_attempts, /* evac term attempts */
4127 lab_waste, /* alloc buffer waste */
4128 lab_undo_waste /* undo waste */
4129 );
4130 }
4131
4132 // Close the inner scope so that the ResourceMark and HandleMark
4133 // destructors are executed here and are included as part of the
4134 // "GC Worker Time".
4135 }
4136 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4137 }
4138 };
4139
4140 void G1CollectedHeap::print_termination_stats_hdr() {
4141 log_debug(gc, task, stats)("GC Termination Stats");
4142 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4143 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
4144 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4145 }
4146
4147 void G1CollectedHeap::print_termination_stats(uint worker_id,
4148 double elapsed_ms,
4149 double strong_roots_ms,
4150 double term_ms,
4151 size_t term_attempts,
4152 size_t alloc_buffer_waste,
4153 size_t undo_waste) const {
4154 log_debug(gc, task, stats)
4155 ("%3d %9.2f %9.2f %6.2f "
4156 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4157 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4158 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4159 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4160 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4161 alloc_buffer_waste * HeapWordSize / K,
4162 undo_waste * HeapWordSize / K);
4163 }
4164
4165 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4166 private:
4167 BoolObjectClosure* _is_alive;
4168 int _initial_string_table_size;
4169 int _initial_symbol_table_size;
4170
4171 bool _process_strings;
4172 int _strings_processed;
4173 int _strings_removed;
4174
4175 bool _process_symbols;
4176 int _symbols_processed;
4177 int _symbols_removed;
4178
4179 public:
4180 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4181 AbstractGangTask("String/Symbol Unlinking"),
4182 _is_alive(is_alive),
4183 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4184 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4185
4186 _initial_string_table_size = StringTable::the_table()->table_size();
4187 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4188 if (process_strings) {
4189 StringTable::clear_parallel_claimed_index();
4190 }
4191 if (process_symbols) {
4192 SymbolTable::clear_parallel_claimed_index();
4193 }
4194 }
4195
4196 ~G1StringSymbolTableUnlinkTask() {
4197 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4198 "claim value %d after unlink less than initial string table size %d",
4199 StringTable::parallel_claimed_index(), _initial_string_table_size);
4200 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4201 "claim value %d after unlink less than initial symbol table size %d",
4202 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4203
4204 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
4205 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4206 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4207 strings_processed(), strings_removed(),
4208 symbols_processed(), symbols_removed());
4209 }
4210
4211 void work(uint worker_id) {
4212 int strings_processed = 0;
4213 int strings_removed = 0;
4214 int symbols_processed = 0;
4215 int symbols_removed = 0;
4216 if (_process_strings) {
4217 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4218 Atomic::add(strings_processed, &_strings_processed);
4219 Atomic::add(strings_removed, &_strings_removed);
4220 }
4221 if (_process_symbols) {
4222 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4223 Atomic::add(symbols_processed, &_symbols_processed);
4224 Atomic::add(symbols_removed, &_symbols_removed);
4225 }
4226 }
4227
4228 size_t strings_processed() const { return (size_t)_strings_processed; }
4229 size_t strings_removed() const { return (size_t)_strings_removed; }
4230
4231 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4232 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4233 };
4234
4235 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4236 private:
4237 static Monitor* _lock;
4238
4239 BoolObjectClosure* const _is_alive;
4240 const bool _unloading_occurred;
4241 const uint _num_workers;
4242
4243 // Variables used to claim nmethods.
4244 nmethod* _first_nmethod;
4245 volatile nmethod* _claimed_nmethod;
4246
4247 // The list of nmethods that need to be processed by the second pass.
4248 volatile nmethod* _postponed_list;
4249 volatile uint _num_entered_barrier;
4250
4251 public:
4252 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4253 _is_alive(is_alive),
4254 _unloading_occurred(unloading_occurred),
4255 _num_workers(num_workers),
4256 _first_nmethod(NULL),
4257 _claimed_nmethod(NULL),
4258 _postponed_list(NULL),
4259 _num_entered_barrier(0)
4260 {
4261 nmethod::increase_unloading_clock();
4262 // Get first alive nmethod
4263 NMethodIterator iter = NMethodIterator();
4264 if(iter.next_alive()) {
4265 _first_nmethod = iter.method();
4266 }
4267 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4268 }
4269
4270 ~G1CodeCacheUnloadingTask() {
4271 CodeCache::verify_clean_inline_caches();
4272
4273 CodeCache::set_needs_cache_clean(false);
4274 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4275
4276 CodeCache::verify_icholder_relocations();
4277 }
4278
4279 private:
4280 void add_to_postponed_list(nmethod* nm) {
4281 nmethod* old;
4282 do {
4283 old = (nmethod*)_postponed_list;
4284 nm->set_unloading_next(old);
4285 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4286 }
4287
4288 void clean_nmethod(nmethod* nm) {
4289 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4290
4291 if (postponed) {
4292 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4293 add_to_postponed_list(nm);
4294 }
4295
4296 // Mark that this thread has been cleaned/unloaded.
4297 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4298 nm->set_unloading_clock(nmethod::global_unloading_clock());
4299 }
4300
4301 void clean_nmethod_postponed(nmethod* nm) {
4302 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4303 }
4304
4305 static const int MaxClaimNmethods = 16;
4306
4307 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4308 nmethod* first;
4309 NMethodIterator last;
4310
4311 do {
4312 *num_claimed_nmethods = 0;
4313
4314 first = (nmethod*)_claimed_nmethod;
4315 last = NMethodIterator(first);
4316
4317 if (first != NULL) {
4318
4319 for (int i = 0; i < MaxClaimNmethods; i++) {
4320 if (!last.next_alive()) {
4321 break;
4322 }
4323 claimed_nmethods[i] = last.method();
4324 (*num_claimed_nmethods)++;
4325 }
4326 }
4327
4328 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4329 }
4330
4331 nmethod* claim_postponed_nmethod() {
4332 nmethod* claim;
4333 nmethod* next;
4334
4335 do {
4336 claim = (nmethod*)_postponed_list;
4337 if (claim == NULL) {
4338 return NULL;
4339 }
4340
4341 next = claim->unloading_next();
4342
4343 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4344
4345 return claim;
4346 }
4347
4348 public:
4349 // Mark that we're done with the first pass of nmethod cleaning.
4350 void barrier_mark(uint worker_id) {
4351 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4352 _num_entered_barrier++;
4353 if (_num_entered_barrier == _num_workers) {
4354 ml.notify_all();
4355 }
4356 }
4357
4358 // See if we have to wait for the other workers to
4359 // finish their first-pass nmethod cleaning work.
4360 void barrier_wait(uint worker_id) {
4361 if (_num_entered_barrier < _num_workers) {
4362 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4363 while (_num_entered_barrier < _num_workers) {
4364 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4365 }
4366 }
4367 }
4368
4369 // Cleaning and unloading of nmethods. Some work has to be postponed
4370 // to the second pass, when we know which nmethods survive.
4371 void work_first_pass(uint worker_id) {
4372 // The first nmethods is claimed by the first worker.
4373 if (worker_id == 0 && _first_nmethod != NULL) {
4374 clean_nmethod(_first_nmethod);
4375 _first_nmethod = NULL;
4376 }
4377
4378 int num_claimed_nmethods;
4379 nmethod* claimed_nmethods[MaxClaimNmethods];
4380
4381 while (true) {
4382 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4383
4384 if (num_claimed_nmethods == 0) {
4385 break;
4386 }
4387
4388 for (int i = 0; i < num_claimed_nmethods; i++) {
4389 clean_nmethod(claimed_nmethods[i]);
4390 }
4391 }
4392 }
4393
4394 void work_second_pass(uint worker_id) {
4395 nmethod* nm;
4396 // Take care of postponed nmethods.
4397 while ((nm = claim_postponed_nmethod()) != NULL) {
4398 clean_nmethod_postponed(nm);
4399 }
4400 }
4401 };
4402
4403 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4404
4405 class G1KlassCleaningTask : public StackObj {
4406 BoolObjectClosure* _is_alive;
4407 volatile jint _clean_klass_tree_claimed;
4408 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4409
4410 public:
4411 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4412 _is_alive(is_alive),
4413 _clean_klass_tree_claimed(0),
4414 _klass_iterator() {
4415 }
4416
4417 private:
4418 bool claim_clean_klass_tree_task() {
4419 if (_clean_klass_tree_claimed) {
4420 return false;
4421 }
4422
4423 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4424 }
4425
4426 InstanceKlass* claim_next_klass() {
4427 Klass* klass;
4428 do {
4429 klass =_klass_iterator.next_klass();
4430 } while (klass != NULL && !klass->is_instance_klass());
4431
4432 // this can be null so don't call InstanceKlass::cast
4433 return static_cast<InstanceKlass*>(klass);
4434 }
4435
4436 public:
4437
4438 void clean_klass(InstanceKlass* ik) {
4439 ik->clean_weak_instanceklass_links(_is_alive);
4440 }
4441
4442 void work() {
4443 ResourceMark rm;
4444
4445 // One worker will clean the subklass/sibling klass tree.
4446 if (claim_clean_klass_tree_task()) {
4447 Klass::clean_subklass_tree(_is_alive);
4448 }
4449
4450 // All workers will help cleaning the classes,
4451 InstanceKlass* klass;
4452 while ((klass = claim_next_klass()) != NULL) {
4453 clean_klass(klass);
4454 }
4455 }
4456 };
4457
4458 // To minimize the remark pause times, the tasks below are done in parallel.
4459 class G1ParallelCleaningTask : public AbstractGangTask {
4460 private:
4461 G1StringSymbolTableUnlinkTask _string_symbol_task;
4462 G1CodeCacheUnloadingTask _code_cache_task;
4463 G1KlassCleaningTask _klass_cleaning_task;
4464
4465 public:
4466 // The constructor is run in the VMThread.
4467 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4468 AbstractGangTask("Parallel Cleaning"),
4469 _string_symbol_task(is_alive, process_strings, process_symbols),
4470 _code_cache_task(num_workers, is_alive, unloading_occurred),
4471 _klass_cleaning_task(is_alive) {
4472 }
4473
4474 // The parallel work done by all worker threads.
4475 void work(uint worker_id) {
4476 // Do first pass of code cache cleaning.
4477 _code_cache_task.work_first_pass(worker_id);
4478
4479 // Let the threads mark that the first pass is done.
4480 _code_cache_task.barrier_mark(worker_id);
4481
4482 // Clean the Strings and Symbols.
4483 _string_symbol_task.work(worker_id);
4484
4485 // Wait for all workers to finish the first code cache cleaning pass.
4486 _code_cache_task.barrier_wait(worker_id);
4487
4488 // Do the second code cache cleaning work, which realize on
4489 // the liveness information gathered during the first pass.
4490 _code_cache_task.work_second_pass(worker_id);
4491
4492 // Clean all klasses that were not unloaded.
4493 _klass_cleaning_task.work();
4494 }
4495 };
4496
4497
4498 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4499 bool process_strings,
4500 bool process_symbols,
4501 bool class_unloading_occurred) {
4502 uint n_workers = workers()->active_workers();
4503
4504 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4505 n_workers, class_unloading_occurred);
4506 workers()->run_task(&g1_unlink_task);
4507 }
4508
4509 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4510 bool process_strings, bool process_symbols) {
4511 {
4512 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4513 workers()->run_task(&g1_unlink_task);
4514 }
4515
4516 if (G1StringDedup::is_enabled()) {
4517 G1StringDedup::unlink(is_alive);
4518 }
4519 }
4520
4521 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4522 private:
4523 DirtyCardQueueSet* _queue;
4524 G1CollectedHeap* _g1h;
4525 public:
4526 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4527 _queue(queue), _g1h(g1h) { }
4528
4529 virtual void work(uint worker_id) {
4530 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4531 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4532
4533 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4534 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4535
4536 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4537 }
4538 };
4539
4540 void G1CollectedHeap::redirty_logged_cards() {
4541 double redirty_logged_cards_start = os::elapsedTime();
4542
4543 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4544 dirty_card_queue_set().reset_for_par_iteration();
4545 workers()->run_task(&redirty_task);
4546
4547 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4548 dcq.merge_bufferlists(&dirty_card_queue_set());
4549 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4550
4551 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4552 }
4553
4554 // Weak Reference Processing support
4555
4556 // An always "is_alive" closure that is used to preserve referents.
4557 // If the object is non-null then it's alive. Used in the preservation
4558 // of referent objects that are pointed to by reference objects
4559 // discovered by the CM ref processor.
4560 class G1AlwaysAliveClosure: public BoolObjectClosure {
4561 G1CollectedHeap* _g1;
4562 public:
4563 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4564 bool do_object_b(oop p) {
4565 if (p != NULL) {
4566 return true;
4567 }
4568 return false;
4569 }
4570 };
4571
4572 bool G1STWIsAliveClosure::do_object_b(oop p) {
4573 // An object is reachable if it is outside the collection set,
4574 // or is inside and copied.
4575 return !_g1->is_in_cset(p) || p->is_forwarded();
4576 }
4577
4578 // Non Copying Keep Alive closure
4579 class G1KeepAliveClosure: public OopClosure {
4580 G1CollectedHeap* _g1;
4581 public:
4582 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4583 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4584 void do_oop(oop* p) {
4585 oop obj = *p;
4586 assert(obj != NULL, "the caller should have filtered out NULL values");
4587
4588 const InCSetState cset_state = _g1->in_cset_state(obj);
4589 if (!cset_state.is_in_cset_or_humongous()) {
4590 return;
4591 }
4592 if (cset_state.is_in_cset()) {
4593 assert( obj->is_forwarded(), "invariant" );
4594 *p = obj->forwardee();
4595 } else {
4596 assert(!obj->is_forwarded(), "invariant" );
4597 assert(cset_state.is_humongous(),
4598 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4599 _g1->set_humongous_is_live(obj);
4600 }
4601 }
4602 };
4603
4604 // Copying Keep Alive closure - can be called from both
4605 // serial and parallel code as long as different worker
4606 // threads utilize different G1ParScanThreadState instances
4607 // and different queues.
4608
4609 class G1CopyingKeepAliveClosure: public OopClosure {
4610 G1CollectedHeap* _g1h;
4611 OopClosure* _copy_non_heap_obj_cl;
4612 G1ParScanThreadState* _par_scan_state;
4613
4614 public:
4615 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4616 OopClosure* non_heap_obj_cl,
4617 G1ParScanThreadState* pss):
4618 _g1h(g1h),
4619 _copy_non_heap_obj_cl(non_heap_obj_cl),
4620 _par_scan_state(pss)
4621 {}
4622
4623 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4624 virtual void do_oop( oop* p) { do_oop_work(p); }
4625
4626 template <class T> void do_oop_work(T* p) {
4627 oop obj = oopDesc::load_decode_heap_oop(p);
4628
4629 if (_g1h->is_in_cset_or_humongous(obj)) {
4630 // If the referent object has been forwarded (either copied
4631 // to a new location or to itself in the event of an
4632 // evacuation failure) then we need to update the reference
4633 // field and, if both reference and referent are in the G1
4634 // heap, update the RSet for the referent.
4635 //
4636 // If the referent has not been forwarded then we have to keep
4637 // it alive by policy. Therefore we have copy the referent.
4638 //
4639 // If the reference field is in the G1 heap then we can push
4640 // on the PSS queue. When the queue is drained (after each
4641 // phase of reference processing) the object and it's followers
4642 // will be copied, the reference field set to point to the
4643 // new location, and the RSet updated. Otherwise we need to
4644 // use the the non-heap or metadata closures directly to copy
4645 // the referent object and update the pointer, while avoiding
4646 // updating the RSet.
4647
4648 if (_g1h->is_in_g1_reserved(p)) {
4649 _par_scan_state->push_on_queue(p);
4650 } else {
4651 assert(!Metaspace::contains((const void*)p),
4652 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4653 _copy_non_heap_obj_cl->do_oop(p);
4654 }
4655 }
4656 }
4657 };
4658
4659 // Serial drain queue closure. Called as the 'complete_gc'
4660 // closure for each discovered list in some of the
4661 // reference processing phases.
4662
4663 class G1STWDrainQueueClosure: public VoidClosure {
4664 protected:
4665 G1CollectedHeap* _g1h;
4666 G1ParScanThreadState* _par_scan_state;
4667
4668 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4669
4670 public:
4671 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4672 _g1h(g1h),
4673 _par_scan_state(pss)
4674 { }
4675
4676 void do_void() {
4677 G1ParScanThreadState* const pss = par_scan_state();
4678 pss->trim_queue();
4679 }
4680 };
4681
4682 // Parallel Reference Processing closures
4683
4684 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4685 // processing during G1 evacuation pauses.
4686
4687 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4688 private:
4689 G1CollectedHeap* _g1h;
4690 G1ParScanThreadStateSet* _pss;
4691 RefToScanQueueSet* _queues;
4692 WorkGang* _workers;
4693 uint _active_workers;
4694
4695 public:
4696 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4697 G1ParScanThreadStateSet* per_thread_states,
4698 WorkGang* workers,
4699 RefToScanQueueSet *task_queues,
4700 uint n_workers) :
4701 _g1h(g1h),
4702 _pss(per_thread_states),
4703 _queues(task_queues),
4704 _workers(workers),
4705 _active_workers(n_workers)
4706 {
4707 assert(n_workers > 0, "shouldn't call this otherwise");
4708 }
4709
4710 // Executes the given task using concurrent marking worker threads.
4711 virtual void execute(ProcessTask& task);
4712 virtual void execute(EnqueueTask& task);
4713 };
4714
4715 // Gang task for possibly parallel reference processing
4716
4717 class G1STWRefProcTaskProxy: public AbstractGangTask {
4718 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4719 ProcessTask& _proc_task;
4720 G1CollectedHeap* _g1h;
4721 G1ParScanThreadStateSet* _pss;
4722 RefToScanQueueSet* _task_queues;
4723 ParallelTaskTerminator* _terminator;
4724
4725 public:
4726 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4727 G1CollectedHeap* g1h,
4728 G1ParScanThreadStateSet* per_thread_states,
4729 RefToScanQueueSet *task_queues,
4730 ParallelTaskTerminator* terminator) :
4731 AbstractGangTask("Process reference objects in parallel"),
4732 _proc_task(proc_task),
4733 _g1h(g1h),
4734 _pss(per_thread_states),
4735 _task_queues(task_queues),
4736 _terminator(terminator)
4737 {}
4738
4739 virtual void work(uint worker_id) {
4740 // The reference processing task executed by a single worker.
4741 ResourceMark rm;
4742 HandleMark hm;
4743
4744 G1STWIsAliveClosure is_alive(_g1h);
4745
4746 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4747 pss->set_ref_processor(NULL);
4748
4749 // Keep alive closure.
4750 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4751
4752 // Complete GC closure
4753 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4754
4755 // Call the reference processing task's work routine.
4756 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4757
4758 // Note we cannot assert that the refs array is empty here as not all
4759 // of the processing tasks (specifically phase2 - pp2_work) execute
4760 // the complete_gc closure (which ordinarily would drain the queue) so
4761 // the queue may not be empty.
4762 }
4763 };
4764
4765 // Driver routine for parallel reference processing.
4766 // Creates an instance of the ref processing gang
4767 // task and has the worker threads execute it.
4768 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4769 assert(_workers != NULL, "Need parallel worker threads.");
4770
4771 ParallelTaskTerminator terminator(_active_workers, _queues);
4772 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4773
4774 _workers->run_task(&proc_task_proxy);
4775 }
4776
4777 // Gang task for parallel reference enqueueing.
4778
4779 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4780 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4781 EnqueueTask& _enq_task;
4782
4783 public:
4784 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4785 AbstractGangTask("Enqueue reference objects in parallel"),
4786 _enq_task(enq_task)
4787 { }
4788
4789 virtual void work(uint worker_id) {
4790 _enq_task.work(worker_id);
4791 }
4792 };
4793
4794 // Driver routine for parallel reference enqueueing.
4795 // Creates an instance of the ref enqueueing gang
4796 // task and has the worker threads execute it.
4797
4798 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4799 assert(_workers != NULL, "Need parallel worker threads.");
4800
4801 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4802
4803 _workers->run_task(&enq_task_proxy);
4804 }
4805
4806 // End of weak reference support closures
4807
4808 // Abstract task used to preserve (i.e. copy) any referent objects
4809 // that are in the collection set and are pointed to by reference
4810 // objects discovered by the CM ref processor.
4811
4812 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4813 protected:
4814 G1CollectedHeap* _g1h;
4815 G1ParScanThreadStateSet* _pss;
4816 RefToScanQueueSet* _queues;
4817 ParallelTaskTerminator _terminator;
4818 uint _n_workers;
4819
4820 public:
4821 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4822 AbstractGangTask("ParPreserveCMReferents"),
4823 _g1h(g1h),
4824 _pss(per_thread_states),
4825 _queues(task_queues),
4826 _terminator(workers, _queues),
4827 _n_workers(workers)
4828 { }
4829
4830 void work(uint worker_id) {
4831 ResourceMark rm;
4832 HandleMark hm;
4833
4834 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4835 pss->set_ref_processor(NULL);
4836 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4837
4838 // Is alive closure
4839 G1AlwaysAliveClosure always_alive(_g1h);
4840
4841 // Copying keep alive closure. Applied to referent objects that need
4842 // to be copied.
4843 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4844
4845 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4846
4847 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4848 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4849
4850 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4851 // So this must be true - but assert just in case someone decides to
4852 // change the worker ids.
4853 assert(worker_id < limit, "sanity");
4854 assert(!rp->discovery_is_atomic(), "check this code");
4855
4856 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4857 for (uint idx = worker_id; idx < limit; idx += stride) {
4858 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4859
4860 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4861 while (iter.has_next()) {
4862 // Since discovery is not atomic for the CM ref processor, we
4863 // can see some null referent objects.
4864 iter.load_ptrs(DEBUG_ONLY(true));
4865 oop ref = iter.obj();
4866
4867 // This will filter nulls.
4868 if (iter.is_referent_alive()) {
4869 iter.make_referent_alive();
4870 }
4871 iter.move_to_next();
4872 }
4873 }
4874
4875 // Drain the queue - which may cause stealing
4876 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4877 drain_queue.do_void();
4878 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4879 assert(pss->queue_is_empty(), "should be");
4880 }
4881 };
4882
4883 void G1CollectedHeap::process_weak_jni_handles() {
4884 double ref_proc_start = os::elapsedTime();
4885
4886 G1STWIsAliveClosure is_alive(this);
4887 G1KeepAliveClosure keep_alive(this);
4888 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4889
4890 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4891 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4892 }
4893
4894 // Weak Reference processing during an evacuation pause (part 1).
4895 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4896 double ref_proc_start = os::elapsedTime();
4897
4898 ReferenceProcessor* rp = _ref_processor_stw;
4899 assert(rp->discovery_enabled(), "should have been enabled");
4900
4901 // Any reference objects, in the collection set, that were 'discovered'
4902 // by the CM ref processor should have already been copied (either by
4903 // applying the external root copy closure to the discovered lists, or
4904 // by following an RSet entry).
4905 //
4906 // But some of the referents, that are in the collection set, that these
4907 // reference objects point to may not have been copied: the STW ref
4908 // processor would have seen that the reference object had already
4909 // been 'discovered' and would have skipped discovering the reference,
4910 // but would not have treated the reference object as a regular oop.
4911 // As a result the copy closure would not have been applied to the
4912 // referent object.
4913 //
4914 // We need to explicitly copy these referent objects - the references
4915 // will be processed at the end of remarking.
4916 //
4917 // We also need to do this copying before we process the reference
4918 // objects discovered by the STW ref processor in case one of these
4919 // referents points to another object which is also referenced by an
4920 // object discovered by the STW ref processor.
4921
4922 uint no_of_gc_workers = workers()->active_workers();
4923
4924 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4925 per_thread_states,
4926 no_of_gc_workers,
4927 _task_queues);
4928
4929 workers()->run_task(&keep_cm_referents);
4930
4931 // Closure to test whether a referent is alive.
4932 G1STWIsAliveClosure is_alive(this);
4933
4934 // Even when parallel reference processing is enabled, the processing
4935 // of JNI refs is serial and performed serially by the current thread
4936 // rather than by a worker. The following PSS will be used for processing
4937 // JNI refs.
4938
4939 // Use only a single queue for this PSS.
4940 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4941 pss->set_ref_processor(NULL);
4942 assert(pss->queue_is_empty(), "pre-condition");
4943
4944 // Keep alive closure.
4945 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4946
4947 // Serial Complete GC closure
4948 G1STWDrainQueueClosure drain_queue(this, pss);
4949
4950 // Setup the soft refs policy...
4951 rp->setup_policy(false);
4952
4953 ReferenceProcessorStats stats;
4954 if (!rp->processing_is_mt()) {
4955 // Serial reference processing...
4956 stats = rp->process_discovered_references(&is_alive,
4957 &keep_alive,
4958 &drain_queue,
4959 NULL,
4960 _gc_timer_stw);
4961 } else {
4962 // Parallel reference processing
4963 assert(rp->num_q() == no_of_gc_workers, "sanity");
4964 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4965
4966 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4967 stats = rp->process_discovered_references(&is_alive,
4968 &keep_alive,
4969 &drain_queue,
4970 &par_task_executor,
4971 _gc_timer_stw);
4972 }
4973
4974 _gc_tracer_stw->report_gc_reference_stats(stats);
4975
4976 // We have completed copying any necessary live referent objects.
4977 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4978
4979 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4980 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4981 }
4982
4983 // Weak Reference processing during an evacuation pause (part 2).
4984 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4985 double ref_enq_start = os::elapsedTime();
4986
4987 ReferenceProcessor* rp = _ref_processor_stw;
4988 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4989
4990 // Now enqueue any remaining on the discovered lists on to
4991 // the pending list.
4992 if (!rp->processing_is_mt()) {
4993 // Serial reference processing...
4994 rp->enqueue_discovered_references();
4995 } else {
4996 // Parallel reference enqueueing
4997
4998 uint n_workers = workers()->active_workers();
4999
5000 assert(rp->num_q() == n_workers, "sanity");
5001 assert(n_workers <= rp->max_num_q(), "sanity");
5002
5003 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5004 rp->enqueue_discovered_references(&par_task_executor);
5005 }
5006
5007 rp->verify_no_references_recorded();
5008 assert(!rp->discovery_enabled(), "should have been disabled");
5009
5010 // FIXME
5011 // CM's reference processing also cleans up the string and symbol tables.
5012 // Should we do that here also? We could, but it is a serial operation
5013 // and could significantly increase the pause time.
5014
5015 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5016 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5017 }
5018
5019 void G1CollectedHeap::pre_evacuate_collection_set() {
5020 _expand_heap_after_alloc_failure = true;
5021 _evacuation_failed = false;
5022
5023 // Disable the hot card cache.
5024 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5025 hot_card_cache->reset_hot_cache_claimed_index();
5026 hot_card_cache->set_use_cache(false);
5027
5028 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5029 }
5030
5031 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5032 // Should G1EvacuationFailureALot be in effect for this GC?
5033 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5034
5035 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5036 double start_par_time_sec = os::elapsedTime();
5037 double end_par_time_sec;
5038
5039 {
5040 const uint n_workers = workers()->active_workers();
5041 G1RootProcessor root_processor(this, n_workers);
5042 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5043 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5044 if (collector_state()->during_initial_mark_pause()) {
5045 ClassLoaderDataGraph::clear_claimed_marks();
5046 }
5047
5048 print_termination_stats_hdr();
5049
5050 workers()->run_task(&g1_par_task);
5051 end_par_time_sec = os::elapsedTime();
5052
5053 // Closing the inner scope will execute the destructor
5054 // for the G1RootProcessor object. We record the current
5055 // elapsed time before closing the scope so that time
5056 // taken for the destructor is NOT included in the
5057 // reported parallel time.
5058 }
5059
5060 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5061
5062 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5063 phase_times->record_par_time(par_time_ms);
5064
5065 double code_root_fixup_time_ms =
5066 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5067 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5068 }
5069
5070 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5071 // Process any discovered reference objects - we have
5072 // to do this _before_ we retire the GC alloc regions
5073 // as we may have to copy some 'reachable' referent
5074 // objects (and their reachable sub-graphs) that were
5075 // not copied during the pause.
5076 if (g1_policy()->should_process_references()) {
5077 process_discovered_references(per_thread_states);
5078 } else {
5079 ref_processor_stw()->verify_no_references_recorded();
5080 process_weak_jni_handles();
5081 }
5082
5083 if (G1StringDedup::is_enabled()) {
5084 double fixup_start = os::elapsedTime();
5085
5086 G1STWIsAliveClosure is_alive(this);
5087 G1KeepAliveClosure keep_alive(this);
5088 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5089
5090 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5091 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5092 }
5093
5094 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5095
5096 if (evacuation_failed()) {
5097 restore_after_evac_failure();
5098
5099 // Reset the G1EvacuationFailureALot counters and flags
5100 // Note: the values are reset only when an actual
5101 // evacuation failure occurs.
5102 NOT_PRODUCT(reset_evacuation_should_fail();)
5103 }
5104
5105 // Enqueue any remaining references remaining on the STW
5106 // reference processor's discovered lists. We need to do
5107 // this after the card table is cleaned (and verified) as
5108 // the act of enqueueing entries on to the pending list
5109 // will log these updates (and dirty their associated
5110 // cards). We need these updates logged to update any
5111 // RSets.
5112 if (g1_policy()->should_process_references()) {
5113 enqueue_discovered_references(per_thread_states);
5114 } else {
5115 g1_policy()->phase_times()->record_ref_enq_time(0);
5116 }
5117
5118 _allocator->release_gc_alloc_regions(evacuation_info);
5119
5120 per_thread_states->flush();
5121
5122 record_obj_copy_mem_stats();
5123
5124 _survivor_evac_stats.adjust_desired_plab_sz();
5125 _old_evac_stats.adjust_desired_plab_sz();
5126
5127 // Reset and re-enable the hot card cache.
5128 // Note the counts for the cards in the regions in the
5129 // collection set are reset when the collection set is freed.
5130 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5131 hot_card_cache->reset_hot_cache();
5132 hot_card_cache->set_use_cache(true);
5133
5134 purge_code_root_memory();
5135
5136 redirty_logged_cards();
5137 #if defined(COMPILER2) || INCLUDE_JVMCI
5138 DerivedPointerTable::update_pointers();
5139 #endif
5140 }
5141
5142 void G1CollectedHeap::record_obj_copy_mem_stats() {
5143 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5144
5145 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5146 create_g1_evac_summary(&_old_evac_stats));
5147 }
5148
5149 void G1CollectedHeap::free_region(HeapRegion* hr,
5150 FreeRegionList* free_list,
5151 bool par,
5152 bool locked) {
5153 assert(!hr->is_free(), "the region should not be free");
5154 assert(!hr->is_empty(), "the region should not be empty");
5155 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5156 assert(free_list != NULL, "pre-condition");
5157
5158 if (G1VerifyBitmaps) {
5159 MemRegion mr(hr->bottom(), hr->end());
5160 concurrent_mark()->clearRangePrevBitmap(mr);
5161 }
5162
5163 // Clear the card counts for this region.
5164 // Note: we only need to do this if the region is not young
5165 // (since we don't refine cards in young regions).
5166 if (!hr->is_young()) {
5167 _cg1r->hot_card_cache()->reset_card_counts(hr);
5168 }
5169 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5170 free_list->add_ordered(hr);
5171 }
5172
5173 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5174 FreeRegionList* free_list,
5175 bool par) {
5176 assert(hr->is_humongous(), "this is only for humongous regions");
5177 assert(free_list != NULL, "pre-condition");
5178 hr->clear_humongous();
5179 free_region(hr, free_list, par);
5180 }
5181
5182 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
5183 const uint humongous_regions_removed) {
5184 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
5185 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5186 _old_set.bulk_remove(old_regions_removed);
5187 _humongous_set.bulk_remove(humongous_regions_removed);
5188 }
5189
5190 }
5191
5192 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5193 assert(list != NULL, "list can't be null");
5194 if (!list->is_empty()) {
5195 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5196 _hrm.insert_list_into_free_list(list);
5197 }
5198 }
5199
5200 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5201 decrease_used(bytes);
5202 }
5203
5204 class G1ParCleanupCTTask : public AbstractGangTask {
5205 G1SATBCardTableModRefBS* _ct_bs;
5206 G1CollectedHeap* _g1h;
5207 HeapRegion* volatile _su_head;
5208 public:
5209 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5210 G1CollectedHeap* g1h) :
5211 AbstractGangTask("G1 Par Cleanup CT Task"),
5212 _ct_bs(ct_bs), _g1h(g1h) { }
5213
5214 void work(uint worker_id) {
5215 HeapRegion* r;
5216 while (r = _g1h->pop_dirty_cards_region()) {
5217 clear_cards(r);
5218 }
5219 }
5220
5221 void clear_cards(HeapRegion* r) {
5222 // Cards of the survivors should have already been dirtied.
5223 if (!r->is_survivor()) {
5224 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5225 }
5226 }
5227 };
5228
5229 #ifndef PRODUCT
5230 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5231 G1CollectedHeap* _g1h;
5232 G1SATBCardTableModRefBS* _ct_bs;
5233 public:
5234 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5235 : _g1h(g1h), _ct_bs(ct_bs) { }
5236 virtual bool doHeapRegion(HeapRegion* r) {
5237 if (r->is_survivor()) {
5238 _g1h->verify_dirty_region(r);
5239 } else {
5240 _g1h->verify_not_dirty_region(r);
5241 }
5242 return false;
5243 }
5244 };
5245
5246 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5247 // All of the region should be clean.
5248 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5249 MemRegion mr(hr->bottom(), hr->end());
5250 ct_bs->verify_not_dirty_region(mr);
5251 }
5252
5253 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5254 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5255 // dirty allocated blocks as they allocate them. The thread that
5256 // retires each region and replaces it with a new one will do a
5257 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5258 // not dirty that area (one less thing to have to do while holding
5259 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5260 // is dirty.
5261 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5262 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5263 if (hr->is_young()) {
5264 ct_bs->verify_g1_young_region(mr);
5265 } else {
5266 ct_bs->verify_dirty_region(mr);
5267 }
5268 }
5269
5270 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5271 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5272 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5273 verify_dirty_region(hr);
5274 }
5275 }
5276
5277 void G1CollectedHeap::verify_dirty_young_regions() {
5278 verify_dirty_young_list(_young_list->first_region());
5279 }
5280
5281 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5282 HeapWord* tams, HeapWord* end) {
5283 guarantee(tams <= end,
5284 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5285 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5286 if (result < end) {
5287 log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5288 log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5289 return false;
5290 }
5291 return true;
5292 }
5293
5294 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5295 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5296 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5297
5298 HeapWord* bottom = hr->bottom();
5299 HeapWord* ptams = hr->prev_top_at_mark_start();
5300 HeapWord* ntams = hr->next_top_at_mark_start();
5301 HeapWord* end = hr->end();
5302
5303 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5304
5305 bool res_n = true;
5306 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5307 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5308 // if we happen to be in that state.
5309 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5310 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5311 }
5312 if (!res_p || !res_n) {
5313 log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5314 log_info(gc, verify)("#### Caller: %s", caller);
5315 return false;
5316 }
5317 return true;
5318 }
5319
5320 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5321 if (!G1VerifyBitmaps) return;
5322
5323 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5324 }
5325
5326 class G1VerifyBitmapClosure : public HeapRegionClosure {
5327 private:
5328 const char* _caller;
5329 G1CollectedHeap* _g1h;
5330 bool _failures;
5331
5332 public:
5333 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5334 _caller(caller), _g1h(g1h), _failures(false) { }
5335
5336 bool failures() { return _failures; }
5337
5338 virtual bool doHeapRegion(HeapRegion* hr) {
5339 bool result = _g1h->verify_bitmaps(_caller, hr);
5340 if (!result) {
5341 _failures = true;
5342 }
5343 return false;
5344 }
5345 };
5346
5347 void G1CollectedHeap::check_bitmaps(const char* caller) {
5348 if (!G1VerifyBitmaps) return;
5349
5350 G1VerifyBitmapClosure cl(caller, this);
5351 heap_region_iterate(&cl);
5352 guarantee(!cl.failures(), "bitmap verification");
5353 }
5354
5355 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5356 private:
5357 bool _failures;
5358 public:
5359 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5360
5361 virtual bool doHeapRegion(HeapRegion* hr) {
5362 uint i = hr->hrm_index();
5363 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5364 if (hr->is_humongous()) {
5365 if (hr->in_collection_set()) {
5366 log_info(gc, verify)("## humongous region %u in CSet", i);
5367 _failures = true;
5368 return true;
5369 }
5370 if (cset_state.is_in_cset()) {
5371 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for humongous region %u", cset_state.value(), i);
5372 _failures = true;
5373 return true;
5374 }
5375 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5376 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for continues humongous region %u", cset_state.value(), i);
5377 _failures = true;
5378 return true;
5379 }
5380 } else {
5381 if (cset_state.is_humongous()) {
5382 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for non-humongous region %u", cset_state.value(), i);
5383 _failures = true;
5384 return true;
5385 }
5386 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5387 log_info(gc, verify)("## in CSet %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5388 hr->in_collection_set(), cset_state.value(), i);
5389 _failures = true;
5390 return true;
5391 }
5392 if (cset_state.is_in_cset()) {
5393 if (hr->is_young() != (cset_state.is_young())) {
5394 log_info(gc, verify)("## is_young %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5395 hr->is_young(), cset_state.value(), i);
5396 _failures = true;
5397 return true;
5398 }
5399 if (hr->is_old() != (cset_state.is_old())) {
5400 log_info(gc, verify)("## is_old %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5401 hr->is_old(), cset_state.value(), i);
5402 _failures = true;
5403 return true;
5404 }
5405 }
5406 }
5407 return false;
5408 }
5409
5410 bool failures() const { return _failures; }
5411 };
5412
5413 bool G1CollectedHeap::check_cset_fast_test() {
5414 G1CheckCSetFastTableClosure cl;
5415 _hrm.iterate(&cl);
5416 return !cl.failures();
5417 }
5418 #endif // PRODUCT
5419
5420 void G1CollectedHeap::cleanUpCardTable() {
5421 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5422 double start = os::elapsedTime();
5423
5424 {
5425 // Iterate over the dirty cards region list.
5426 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5427
5428 workers()->run_task(&cleanup_task);
5429 #ifndef PRODUCT
5430 if (G1VerifyCTCleanup || VerifyAfterGC) {
5431 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5432 heap_region_iterate(&cleanup_verifier);
5433 }
5434 #endif
5435 }
5436
5437 double elapsed = os::elapsedTime() - start;
5438 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5439 }
5440
5441 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5442 size_t pre_used = 0;
5443 FreeRegionList local_free_list("Local List for CSet Freeing");
5444
5445 double young_time_ms = 0.0;
5446 double non_young_time_ms = 0.0;
5447
5448 // Since the collection set is a superset of the the young list,
5449 // all we need to do to clear the young list is clear its
5450 // head and length, and unlink any young regions in the code below
5451 _young_list->clear();
5452
5453 G1CollectorPolicy* policy = g1_policy();
5454
5455 double start_sec = os::elapsedTime();
5456 bool non_young = true;
5457
5458 HeapRegion* cur = cs_head;
5459 int age_bound = -1;
5460 size_t rs_lengths = 0;
5461
5462 while (cur != NULL) {
5463 assert(!is_on_master_free_list(cur), "sanity");
5464 if (non_young) {
5465 if (cur->is_young()) {
5466 double end_sec = os::elapsedTime();
5467 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5468 non_young_time_ms += elapsed_ms;
5469
5470 start_sec = os::elapsedTime();
5471 non_young = false;
5472 }
5473 } else {
5474 if (!cur->is_young()) {
5475 double end_sec = os::elapsedTime();
5476 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5477 young_time_ms += elapsed_ms;
5478
5479 start_sec = os::elapsedTime();
5480 non_young = true;
5481 }
5482 }
5483
5484 rs_lengths += cur->rem_set()->occupied_locked();
5485
5486 HeapRegion* next = cur->next_in_collection_set();
5487 assert(cur->in_collection_set(), "bad CS");
5488 cur->set_next_in_collection_set(NULL);
5489 clear_in_cset(cur);
5490
5491 if (cur->is_young()) {
5492 int index = cur->young_index_in_cset();
5493 assert(index != -1, "invariant");
5494 assert((uint) index < policy->young_cset_region_length(), "invariant");
5495 size_t words_survived = surviving_young_words[index];
5496 cur->record_surv_words_in_group(words_survived);
5497
5498 // At this point the we have 'popped' cur from the collection set
5499 // (linked via next_in_collection_set()) but it is still in the
5500 // young list (linked via next_young_region()). Clear the
5501 // _next_young_region field.
5502 cur->set_next_young_region(NULL);
5503 } else {
5504 int index = cur->young_index_in_cset();
5505 assert(index == -1, "invariant");
5506 }
5507
5508 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5509 (!cur->is_young() && cur->young_index_in_cset() == -1),
5510 "invariant" );
5511
5512 if (!cur->evacuation_failed()) {
5513 MemRegion used_mr = cur->used_region();
5514
5515 // And the region is empty.
5516 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5517 pre_used += cur->used();
5518 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5519 } else {
5520 cur->uninstall_surv_rate_group();
5521 if (cur->is_young()) {
5522 cur->set_young_index_in_cset(-1);
5523 }
5524 cur->set_evacuation_failed(false);
5525 // When moving a young gen region to old gen, we "allocate" that whole region
5526 // there. This is in addition to any already evacuated objects. Notify the
5527 // policy about that.
5528 // Old gen regions do not cause an additional allocation: both the objects
5529 // still in the region and the ones already moved are accounted for elsewhere.
5530 if (cur->is_young()) {
5531 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5532 }
5533 // The region is now considered to be old.
5534 cur->set_old();
5535 // Do some allocation statistics accounting. Regions that failed evacuation
5536 // are always made old, so there is no need to update anything in the young
5537 // gen statistics, but we need to update old gen statistics.
5538 size_t used_words = cur->marked_bytes() / HeapWordSize;
5539 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5540 _old_set.add(cur);
5541 evacuation_info.increment_collectionset_used_after(cur->used());
5542 }
5543 cur = next;
5544 }
5545
5546 evacuation_info.set_regions_freed(local_free_list.length());
5547 policy->record_max_rs_lengths(rs_lengths);
5548 policy->cset_regions_freed();
5549
5550 double end_sec = os::elapsedTime();
5551 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5552
5553 if (non_young) {
5554 non_young_time_ms += elapsed_ms;
5555 } else {
5556 young_time_ms += elapsed_ms;
5557 }
5558
5559 prepend_to_freelist(&local_free_list);
5560 decrement_summary_bytes(pre_used);
5561 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5562 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5563 }
5564
5565 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5566 private:
5567 FreeRegionList* _free_region_list;
5568 HeapRegionSet* _proxy_set;
5569 uint _humongous_regions_removed;
5570 size_t _freed_bytes;
5571 public:
5572
5573 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5574 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5575 }
5576
5577 virtual bool doHeapRegion(HeapRegion* r) {
5578 if (!r->is_starts_humongous()) {
5579 return false;
5580 }
5581
5582 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5583
5584 oop obj = (oop)r->bottom();
5585 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5586
5587 // The following checks whether the humongous object is live are sufficient.
5588 // The main additional check (in addition to having a reference from the roots
5589 // or the young gen) is whether the humongous object has a remembered set entry.
5590 //
5591 // A humongous object cannot be live if there is no remembered set for it
5592 // because:
5593 // - there can be no references from within humongous starts regions referencing
5594 // the object because we never allocate other objects into them.
5595 // (I.e. there are no intra-region references that may be missed by the
5596 // remembered set)
5597 // - as soon there is a remembered set entry to the humongous starts region
5598 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5599 // until the end of a concurrent mark.
5600 //
5601 // It is not required to check whether the object has been found dead by marking
5602 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5603 // all objects allocated during that time are considered live.
5604 // SATB marking is even more conservative than the remembered set.
5605 // So if at this point in the collection there is no remembered set entry,
5606 // nobody has a reference to it.
5607 // At the start of collection we flush all refinement logs, and remembered sets
5608 // are completely up-to-date wrt to references to the humongous object.
5609 //
5610 // Other implementation considerations:
5611 // - never consider object arrays at this time because they would pose
5612 // considerable effort for cleaning up the the remembered sets. This is
5613 // required because stale remembered sets might reference locations that
5614 // are currently allocated into.
5615 uint region_idx = r->hrm_index();
5616 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5617 !r->rem_set()->is_empty()) {
5618 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",
5619 region_idx,
5620 (size_t)obj->size() * HeapWordSize,
5621 p2i(r->bottom()),
5622 r->rem_set()->occupied(),
5623 r->rem_set()->strong_code_roots_list_length(),
5624 next_bitmap->isMarked(r->bottom()),
5625 g1h->is_humongous_reclaim_candidate(region_idx),
5626 obj->is_typeArray()
5627 );
5628 return false;
5629 }
5630
5631 guarantee(obj->is_typeArray(),
5632 "Only eagerly reclaiming type arrays is supported, but the object "
5633 PTR_FORMAT " is not.", p2i(r->bottom()));
5634
5635 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",
5636 region_idx,
5637 (size_t)obj->size() * HeapWordSize,
5638 p2i(r->bottom()),
5639 r->rem_set()->occupied(),
5640 r->rem_set()->strong_code_roots_list_length(),
5641 next_bitmap->isMarked(r->bottom()),
5642 g1h->is_humongous_reclaim_candidate(region_idx),
5643 obj->is_typeArray()
5644 );
5645
5646 // Need to clear mark bit of the humongous object if already set.
5647 if (next_bitmap->isMarked(r->bottom())) {
5648 next_bitmap->clear(r->bottom());
5649 }
5650 do {
5651 HeapRegion* next = g1h->next_region_in_humongous(r);
5652 _freed_bytes += r->used();
5653 r->set_containing_set(NULL);
5654 _humongous_regions_removed++;
5655 g1h->free_humongous_region(r, _free_region_list, false);
5656 r = next;
5657 } while (r != NULL);
5658
5659 return false;
5660 }
5661
5662 uint humongous_free_count() {
5663 return _humongous_regions_removed;
5664 }
5665
5666 size_t bytes_freed() const {
5667 return _freed_bytes;
5668 }
5669 };
5670
5671 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5672 assert_at_safepoint(true);
5673
5674 if (!G1EagerReclaimHumongousObjects ||
5675 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5676 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5677 return;
5678 }
5679
5680 double start_time = os::elapsedTime();
5681
5682 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5683
5684 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5685 heap_region_iterate(&cl);
5686
5687 remove_from_old_sets(0, cl.humongous_free_count());
5688
5689 G1HRPrinter* hrp = hr_printer();
5690 if (hrp->is_active()) {
5691 FreeRegionListIterator iter(&local_cleanup_list);
5692 while (iter.more_available()) {
5693 HeapRegion* hr = iter.get_next();
5694 hrp->cleanup(hr);
5695 }
5696 }
5697
5698 prepend_to_freelist(&local_cleanup_list);
5699 decrement_summary_bytes(cl.bytes_freed());
5700
5701 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5702 cl.humongous_free_count());
5703 }
5704
5705 // This routine is similar to the above but does not record
5706 // any policy statistics or update free lists; we are abandoning
5707 // the current incremental collection set in preparation of a
5708 // full collection. After the full GC we will start to build up
5709 // the incremental collection set again.
5710 // This is only called when we're doing a full collection
5711 // and is immediately followed by the tearing down of the young list.
5712
5713 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5714 HeapRegion* cur = cs_head;
5715
5716 while (cur != NULL) {
5717 HeapRegion* next = cur->next_in_collection_set();
5718 assert(cur->in_collection_set(), "bad CS");
5719 cur->set_next_in_collection_set(NULL);
5720 clear_in_cset(cur);
5721 cur->set_young_index_in_cset(-1);
5722 cur = next;
5723 }
5724 }
5725
5726 void G1CollectedHeap::set_free_regions_coming() {
5727 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5728
5729 assert(!free_regions_coming(), "pre-condition");
5730 _free_regions_coming = true;
5731 }
5732
5733 void G1CollectedHeap::reset_free_regions_coming() {
5734 assert(free_regions_coming(), "pre-condition");
5735
5736 {
5737 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5738 _free_regions_coming = false;
5739 SecondaryFreeList_lock->notify_all();
5740 }
5741
5742 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5743 }
5744
5745 void G1CollectedHeap::wait_while_free_regions_coming() {
5746 // Most of the time we won't have to wait, so let's do a quick test
5747 // first before we take the lock.
5748 if (!free_regions_coming()) {
5749 return;
5750 }
5751
5752 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5753
5754 {
5755 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5756 while (free_regions_coming()) {
5757 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5758 }
5759 }
5760
5761 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5762 }
5763
5764 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5765 return _allocator->is_retained_old_region(hr);
5766 }
5767
5768 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5769 _young_list->push_region(hr);
5770 }
5771
5772 class NoYoungRegionsClosure: public HeapRegionClosure {
5773 private:
5774 bool _success;
5775 public:
5776 NoYoungRegionsClosure() : _success(true) { }
5777 bool doHeapRegion(HeapRegion* r) {
5778 if (r->is_young()) {
5779 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5780 p2i(r->bottom()), p2i(r->end()));
5781 _success = false;
5782 }
5783 return false;
5784 }
5785 bool success() { return _success; }
5786 };
5787
5788 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5789 bool ret = _young_list->check_list_empty(check_sample);
5790
5791 if (check_heap) {
5792 NoYoungRegionsClosure closure;
5793 heap_region_iterate(&closure);
5794 ret = ret && closure.success();
5795 }
5796
5797 return ret;
5798 }
5799
5800 class TearDownRegionSetsClosure : public HeapRegionClosure {
5801 private:
5802 HeapRegionSet *_old_set;
5803
5804 public:
5805 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5806
5807 bool doHeapRegion(HeapRegion* r) {
5808 if (r->is_old()) {
5809 _old_set->remove(r);
5810 } else {
5811 // We ignore free regions, we'll empty the free list afterwards.
5812 // We ignore young regions, we'll empty the young list afterwards.
5813 // We ignore humongous regions, we're not tearing down the
5814 // humongous regions set.
5815 assert(r->is_free() || r->is_young() || r->is_humongous(),
5816 "it cannot be another type");
5817 }
5818 return false;
5819 }
5820
5821 ~TearDownRegionSetsClosure() {
5822 assert(_old_set->is_empty(), "post-condition");
5823 }
5824 };
5825
5826 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5827 assert_at_safepoint(true /* should_be_vm_thread */);
5828
5829 if (!free_list_only) {
5830 TearDownRegionSetsClosure cl(&_old_set);
5831 heap_region_iterate(&cl);
5832
5833 // Note that emptying the _young_list is postponed and instead done as
5834 // the first step when rebuilding the regions sets again. The reason for
5835 // this is that during a full GC string deduplication needs to know if
5836 // a collected region was young or old when the full GC was initiated.
5837 }
5838 _hrm.remove_all_free_regions();
5839 }
5840
5841 void G1CollectedHeap::increase_used(size_t bytes) {
5842 _summary_bytes_used += bytes;
5843 }
5844
5845 void G1CollectedHeap::decrease_used(size_t bytes) {
5846 assert(_summary_bytes_used >= bytes,
5847 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5848 _summary_bytes_used, bytes);
5849 _summary_bytes_used -= bytes;
5850 }
5851
5852 void G1CollectedHeap::set_used(size_t bytes) {
5853 _summary_bytes_used = bytes;
5854 }
5855
5856 class RebuildRegionSetsClosure : public HeapRegionClosure {
5857 private:
5858 bool _free_list_only;
5859 HeapRegionSet* _old_set;
5860 HeapRegionManager* _hrm;
5861 size_t _total_used;
5862
5863 public:
5864 RebuildRegionSetsClosure(bool free_list_only,
5865 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5866 _free_list_only(free_list_only),
5867 _old_set(old_set), _hrm(hrm), _total_used(0) {
5868 assert(_hrm->num_free_regions() == 0, "pre-condition");
5869 if (!free_list_only) {
5870 assert(_old_set->is_empty(), "pre-condition");
5871 }
5872 }
5873
5874 bool doHeapRegion(HeapRegion* r) {
5875 if (r->is_empty()) {
5876 // Add free regions to the free list
5877 r->set_free();
5878 r->set_allocation_context(AllocationContext::system());
5879 _hrm->insert_into_free_list(r);
5880 } else if (!_free_list_only) {
5881 assert(!r->is_young(), "we should not come across young regions");
5882
5883 if (r->is_humongous()) {
5884 // We ignore humongous regions. We left the humongous set unchanged.
5885 } else {
5886 // Objects that were compacted would have ended up on regions
5887 // that were previously old or free. Archive regions (which are
5888 // old) will not have been touched.
5889 assert(r->is_free() || r->is_old(), "invariant");
5890 // We now consider them old, so register as such. Leave
5891 // archive regions set that way, however, while still adding
5892 // them to the old set.
5893 if (!r->is_archive()) {
5894 r->set_old();
5895 }
5896 _old_set->add(r);
5897 }
5898 _total_used += r->used();
5899 }
5900
5901 return false;
5902 }
5903
5904 size_t total_used() {
5905 return _total_used;
5906 }
5907 };
5908
5909 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5910 assert_at_safepoint(true /* should_be_vm_thread */);
5911
5912 if (!free_list_only) {
5913 _young_list->empty_list();
5914 }
5915
5916 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5917 heap_region_iterate(&cl);
5918
5919 if (!free_list_only) {
5920 set_used(cl.total_used());
5921 if (_archive_allocator != NULL) {
5922 _archive_allocator->clear_used();
5923 }
5924 }
5925 assert(used_unlocked() == recalculate_used(),
5926 "inconsistent used_unlocked(), "
5927 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5928 used_unlocked(), recalculate_used());
5929 }
5930
5931 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5932 _refine_cte_cl->set_concurrent(concurrent);
5933 }
5934
5935 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5936 HeapRegion* hr = heap_region_containing(p);
5937 return hr->is_in(p);
5938 }
5939
5940 // Methods for the mutator alloc region
5941
5942 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5943 bool force) {
5944 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5945 assert(!force || g1_policy()->can_expand_young_list(),
5946 "if force is true we should be able to expand the young list");
5947 bool young_list_full = g1_policy()->is_young_list_full();
5948 if (force || !young_list_full) {
5949 HeapRegion* new_alloc_region = new_region(word_size,
5950 false /* is_old */,
5951 false /* do_expand */);
5952 if (new_alloc_region != NULL) {
5953 set_region_short_lived_locked(new_alloc_region);
5954 _hr_printer.alloc(new_alloc_region, young_list_full);
5955 check_bitmaps("Mutator Region Allocation", new_alloc_region);
5956 return new_alloc_region;
5957 }
5958 }
5959 return NULL;
5960 }
5961
5962 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5963 size_t allocated_bytes) {
5964 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5965 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5966
5967 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5968 increase_used(allocated_bytes);
5969 _hr_printer.retire(alloc_region);
5970 // We update the eden sizes here, when the region is retired,
5971 // instead of when it's allocated, since this is the point that its
5972 // used space has been recored in _summary_bytes_used.
5973 g1mm()->update_eden_size();
5974 }
5975
5976 // Methods for the GC alloc regions
5977
5978 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5979 uint count,
5980 InCSetState dest) {
5981 assert(FreeList_lock->owned_by_self(), "pre-condition");
5982
5983 if (count < g1_policy()->max_regions(dest)) {
5984 const bool is_survivor = (dest.is_young());
5985 HeapRegion* new_alloc_region = new_region(word_size,
5986 !is_survivor,
5987 true /* do_expand */);
5988 if (new_alloc_region != NULL) {
5989 // We really only need to do this for old regions given that we
5990 // should never scan survivors. But it doesn't hurt to do it
5991 // for survivors too.
5992 new_alloc_region->record_timestamp();
5993 if (is_survivor) {
5994 new_alloc_region->set_survivor();
5995 check_bitmaps("Survivor Region Allocation", new_alloc_region);
5996 } else {
5997 new_alloc_region->set_old();
5998 check_bitmaps("Old Region Allocation", new_alloc_region);
5999 }
6000 _hr_printer.alloc(new_alloc_region);
6001 bool during_im = collector_state()->during_initial_mark_pause();
6002 new_alloc_region->note_start_of_copying(during_im);
6003 return new_alloc_region;
6004 }
6005 }
6006 return NULL;
6007 }
6008
6009 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6010 size_t allocated_bytes,
6011 InCSetState dest) {
6012 bool during_im = collector_state()->during_initial_mark_pause();
6013 alloc_region->note_end_of_copying(during_im);
6014 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6015 if (dest.is_young()) {
6016 young_list()->add_survivor_region(alloc_region);
6017 } else {
6018 _old_set.add(alloc_region);
6019 }
6020 _hr_printer.retire(alloc_region);
6021 }
6022
6023 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6024 bool expanded = false;
6025 uint index = _hrm.find_highest_free(&expanded);
6026
6027 if (index != G1_NO_HRM_INDEX) {
6028 if (expanded) {
6029 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6030 HeapRegion::GrainWords * HeapWordSize);
6031 }
6032 _hrm.allocate_free_regions_starting_at(index, 1);
6033 return region_at(index);
6034 }
6035 return NULL;
6036 }
6037
6038 // Heap region set verification
6039
6040 class VerifyRegionListsClosure : public HeapRegionClosure {
6041 private:
6042 HeapRegionSet* _old_set;
6043 HeapRegionSet* _humongous_set;
6044 HeapRegionManager* _hrm;
6045
6046 public:
6047 uint _old_count;
6048 uint _humongous_count;
6049 uint _free_count;
6050
6051 VerifyRegionListsClosure(HeapRegionSet* old_set,
6052 HeapRegionSet* humongous_set,
6053 HeapRegionManager* hrm) :
6054 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6055 _old_count(), _humongous_count(), _free_count(){ }
6056
6057 bool doHeapRegion(HeapRegion* hr) {
6058 if (hr->is_young()) {
6059 // TODO
6060 } else if (hr->is_humongous()) {
6061 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6062 _humongous_count++;
6063 } else if (hr->is_empty()) {
6064 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6065 _free_count++;
6066 } else if (hr->is_old()) {
6067 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6068 _old_count++;
6069 } else {
6070 // There are no other valid region types. Check for one invalid
6071 // one we can identify: pinned without old or humongous set.
6072 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6073 ShouldNotReachHere();
6074 }
6075 return false;
6076 }
6077
6078 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6079 guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);
6080 guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);
6081 guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);
6082 }
6083 };
6084
6085 void G1CollectedHeap::verify_region_sets() {
6086 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6087
6088 // First, check the explicit lists.
6089 _hrm.verify();
6090 {
6091 // Given that a concurrent operation might be adding regions to
6092 // the secondary free list we have to take the lock before
6093 // verifying it.
6094 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6095 _secondary_free_list.verify_list();
6096 }
6097
6098 // If a concurrent region freeing operation is in progress it will
6099 // be difficult to correctly attributed any free regions we come
6100 // across to the correct free list given that they might belong to
6101 // one of several (free_list, secondary_free_list, any local lists,
6102 // etc.). So, if that's the case we will skip the rest of the
6103 // verification operation. Alternatively, waiting for the concurrent
6104 // operation to complete will have a non-trivial effect on the GC's
6105 // operation (no concurrent operation will last longer than the
6106 // interval between two calls to verification) and it might hide
6107 // any issues that we would like to catch during testing.
6108 if (free_regions_coming()) {
6109 return;
6110 }
6111
6112 // Make sure we append the secondary_free_list on the free_list so
6113 // that all free regions we will come across can be safely
6114 // attributed to the free_list.
6115 append_secondary_free_list_if_not_empty_with_lock();
6116
6117 // Finally, make sure that the region accounting in the lists is
6118 // consistent with what we see in the heap.
6119
6120 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6121 heap_region_iterate(&cl);
6122 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6123 }
6124
6125 // Optimized nmethod scanning
6126
6127 class RegisterNMethodOopClosure: public OopClosure {
6128 G1CollectedHeap* _g1h;
6129 nmethod* _nm;
6130
6131 template <class T> void do_oop_work(T* p) {
6132 T heap_oop = oopDesc::load_heap_oop(p);
6133 if (!oopDesc::is_null(heap_oop)) {
6134 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6135 HeapRegion* hr = _g1h->heap_region_containing(obj);
6136 assert(!hr->is_continues_humongous(),
6137 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6138 " starting at " HR_FORMAT,
6139 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6140
6141 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6142 hr->add_strong_code_root_locked(_nm);
6143 }
6144 }
6145
6146 public:
6147 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6148 _g1h(g1h), _nm(nm) {}
6149
6150 void do_oop(oop* p) { do_oop_work(p); }
6151 void do_oop(narrowOop* p) { do_oop_work(p); }
6152 };
6153
6154 class UnregisterNMethodOopClosure: public OopClosure {
6155 G1CollectedHeap* _g1h;
6156 nmethod* _nm;
6157
6158 template <class T> void do_oop_work(T* p) {
6159 T heap_oop = oopDesc::load_heap_oop(p);
6160 if (!oopDesc::is_null(heap_oop)) {
6161 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6162 HeapRegion* hr = _g1h->heap_region_containing(obj);
6163 assert(!hr->is_continues_humongous(),
6164 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6165 " starting at " HR_FORMAT,
6166 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6167
6168 hr->remove_strong_code_root(_nm);
6169 }
6170 }
6171
6172 public:
6173 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6174 _g1h(g1h), _nm(nm) {}
6175
6176 void do_oop(oop* p) { do_oop_work(p); }
6177 void do_oop(narrowOop* p) { do_oop_work(p); }
6178 };
6179
6180 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6181 CollectedHeap::register_nmethod(nm);
6182
6183 guarantee(nm != NULL, "sanity");
6184 RegisterNMethodOopClosure reg_cl(this, nm);
6185 nm->oops_do(®_cl);
6186 }
6187
6188 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6189 CollectedHeap::unregister_nmethod(nm);
6190
6191 guarantee(nm != NULL, "sanity");
6192 UnregisterNMethodOopClosure reg_cl(this, nm);
6193 nm->oops_do(®_cl, true);
6194 }
6195
6196 void G1CollectedHeap::purge_code_root_memory() {
6197 double purge_start = os::elapsedTime();
6198 G1CodeRootSet::purge();
6199 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6200 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6201 }
6202
6203 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6204 G1CollectedHeap* _g1h;
6205
6206 public:
6207 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6208 _g1h(g1h) {}
6209
6210 void do_code_blob(CodeBlob* cb) {
6211 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6212 if (nm == NULL) {
6213 return;
6214 }
6215
6216 if (ScavengeRootsInCode) {
6217 _g1h->register_nmethod(nm);
6218 }
6219 }
6220 };
6221
6222 void G1CollectedHeap::rebuild_strong_code_roots() {
6223 RebuildStrongCodeRootClosure blob_cl(this);
6224 CodeCache::blobs_do(&blob_cl);
6225 }