1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1EvacStats.inline.hpp"
39 #include "gc/g1/g1GCPhaseTimes.hpp"
40 #include "gc/g1/g1MarkSweep.hpp"
41 #include "gc/g1/g1OopClosures.inline.hpp"
42 #include "gc/g1/g1ParScanThreadState.inline.hpp"
43 #include "gc/g1/g1RegionToSpaceMapper.hpp"
44 #include "gc/g1/g1RemSet.inline.hpp"
45 #include "gc/g1/g1RootClosures.hpp"
46 #include "gc/g1/g1RootProcessor.hpp"
47 #include "gc/g1/g1StringDedup.hpp"
48 #include "gc/g1/g1YCTypes.hpp"
49 #include "gc/g1/heapRegion.inline.hpp"
50 #include "gc/g1/heapRegionRemSet.hpp"
51 #include "gc/g1/heapRegionSet.inline.hpp"
52 #include "gc/g1/suspendibleThreadSet.hpp"
53 #include "gc/g1/vm_operations_g1.hpp"
54 #include "gc/shared/gcHeapSummary.hpp"
55 #include "gc/shared/gcId.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.inline.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "logging/log.hpp"
65 #include "memory/allocation.hpp"
66 #include "memory/iterator.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.inline.hpp"
69 #include "runtime/init.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
76
77 // INVARIANTS/NOTES
78 //
79 // All allocation activity covered by the G1CollectedHeap interface is
80 // serialized by acquiring the HeapLock. This happens in mem_allocate
81 // and allocate_new_tlab, which are the "entry" points to the
82 // allocation code from the rest of the JVM. (Note that this does not
83 // apply to TLAB allocation, which is not part of this interface: it
84 // is done by clients of this interface.)
85
86 // Local to this file.
87
88 class RefineCardTableEntryClosure: public CardTableEntryClosure {
89 bool _concurrent;
90 public:
91 RefineCardTableEntryClosure() : _concurrent(true) { }
92
93 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
94 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
95 // This path is executed by the concurrent refine or mutator threads,
96 // concurrently, and so we do not care if card_ptr contains references
97 // that point into the collection set.
98 assert(!oops_into_cset, "should be");
99
100 if (_concurrent && SuspendibleThreadSet::should_yield()) {
101 // Caller will actually yield.
102 return false;
103 }
104 // Otherwise, we finished successfully; return true.
105 return true;
106 }
107
108 void set_concurrent(bool b) { _concurrent = b; }
109 };
110
111
112 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
113 private:
114 size_t _num_dirtied;
115 G1CollectedHeap* _g1h;
116 G1SATBCardTableLoggingModRefBS* _g1_bs;
117
118 HeapRegion* region_for_card(jbyte* card_ptr) const {
119 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
120 }
121
122 bool will_become_free(HeapRegion* hr) const {
123 // A region will be freed by free_collection_set if the region is in the
124 // collection set and has not had an evacuation failure.
125 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
126 }
127
128 public:
129 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
130 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
131
132 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
133 HeapRegion* hr = region_for_card(card_ptr);
134
135 // Should only dirty cards in regions that won't be freed.
136 if (!will_become_free(hr)) {
137 *card_ptr = CardTableModRefBS::dirty_card_val();
138 _num_dirtied++;
139 }
140
141 return true;
142 }
143
144 size_t num_dirtied() const { return _num_dirtied; }
145 };
146
147
148 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
149 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
150 }
151
152 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
153 // The from card cache is not the memory that is actually committed. So we cannot
154 // take advantage of the zero_filled parameter.
155 reset_from_card_cache(start_idx, num_regions);
156 }
157
158 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
159 {
160 // Claim the right to put the region on the dirty cards region list
161 // by installing a self pointer.
162 HeapRegion* next = hr->get_next_dirty_cards_region();
163 if (next == NULL) {
164 HeapRegion* res = (HeapRegion*)
165 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
166 NULL);
167 if (res == NULL) {
168 HeapRegion* head;
169 do {
170 // Put the region to the dirty cards region list.
171 head = _dirty_cards_region_list;
172 next = (HeapRegion*)
173 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
174 if (next == head) {
175 assert(hr->get_next_dirty_cards_region() == hr,
176 "hr->get_next_dirty_cards_region() != hr");
177 if (next == NULL) {
178 // The last region in the list points to itself.
179 hr->set_next_dirty_cards_region(hr);
180 } else {
181 hr->set_next_dirty_cards_region(next);
182 }
183 }
184 } while (next != head);
185 }
186 }
187 }
188
189 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
190 {
191 HeapRegion* head;
192 HeapRegion* hr;
193 do {
194 head = _dirty_cards_region_list;
195 if (head == NULL) {
196 return NULL;
197 }
198 HeapRegion* new_head = head->get_next_dirty_cards_region();
199 if (head == new_head) {
200 // The last region.
201 new_head = NULL;
202 }
203 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
204 head);
205 } while (hr != head);
206 assert(hr != NULL, "invariant");
207 hr->set_next_dirty_cards_region(NULL);
208 return hr;
209 }
210
211 // Returns true if the reference points to an object that
212 // can move in an incremental collection.
213 bool G1CollectedHeap::is_scavengable(const void* p) {
214 HeapRegion* hr = heap_region_containing(p);
215 return !hr->is_pinned();
216 }
217
218 // Private methods.
219
220 HeapRegion*
221 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
222 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
223 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
224 if (!_secondary_free_list.is_empty()) {
225 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
226 "secondary_free_list has %u entries",
227 _secondary_free_list.length());
228 // It looks as if there are free regions available on the
229 // secondary_free_list. Let's move them to the free_list and try
230 // again to allocate from it.
231 append_secondary_free_list();
232
233 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
234 "empty we should have moved at least one entry to the free_list");
235 HeapRegion* res = _hrm.allocate_free_region(is_old);
236 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
237 "allocated " HR_FORMAT " from secondary_free_list",
238 HR_FORMAT_PARAMS(res));
239 return res;
240 }
241
242 // Wait here until we get notified either when (a) there are no
243 // more free regions coming or (b) some regions have been moved on
244 // the secondary_free_list.
245 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
246 }
247
248 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
249 "could not allocate from secondary_free_list");
250 return NULL;
251 }
252
253 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
254 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
255 "the only time we use this to allocate a humongous region is "
256 "when we are allocating a single humongous region");
257
258 HeapRegion* res;
259 if (G1StressConcRegionFreeing) {
260 if (!_secondary_free_list.is_empty()) {
261 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
262 "forced to look at the secondary_free_list");
263 res = new_region_try_secondary_free_list(is_old);
264 if (res != NULL) {
265 return res;
266 }
267 }
268 }
269
270 res = _hrm.allocate_free_region(is_old);
271
272 if (res == NULL) {
273 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
274 "res == NULL, trying the secondary_free_list");
275 res = new_region_try_secondary_free_list(is_old);
276 }
277 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
278 // Currently, only attempts to allocate GC alloc regions set
279 // do_expand to true. So, we should only reach here during a
280 // safepoint. If this assumption changes we might have to
281 // reconsider the use of _expand_heap_after_alloc_failure.
282 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
283
284 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
285 word_size * HeapWordSize);
286
287 if (expand(word_size * HeapWordSize)) {
288 // Given that expand() succeeded in expanding the heap, and we
289 // always expand the heap by an amount aligned to the heap
290 // region size, the free list should in theory not be empty.
291 // In either case allocate_free_region() will check for NULL.
292 res = _hrm.allocate_free_region(is_old);
293 } else {
294 _expand_heap_after_alloc_failure = false;
295 }
296 }
297 return res;
298 }
299
300 HeapWord*
301 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
302 uint num_regions,
303 size_t word_size,
304 AllocationContext_t context) {
305 assert(first != G1_NO_HRM_INDEX, "pre-condition");
306 assert(is_humongous(word_size), "word_size should be humongous");
307 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
308
309 // Index of last region in the series.
310 uint last = first + num_regions - 1;
311
312 // We need to initialize the region(s) we just discovered. This is
313 // a bit tricky given that it can happen concurrently with
314 // refinement threads refining cards on these regions and
315 // potentially wanting to refine the BOT as they are scanning
316 // those cards (this can happen shortly after a cleanup; see CR
317 // 6991377). So we have to set up the region(s) carefully and in
318 // a specific order.
319
320 // The word size sum of all the regions we will allocate.
321 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
322 assert(word_size <= word_size_sum, "sanity");
323
324 // This will be the "starts humongous" region.
325 HeapRegion* first_hr = region_at(first);
326 // The header of the new object will be placed at the bottom of
327 // the first region.
328 HeapWord* new_obj = first_hr->bottom();
329 // This will be the new top of the new object.
330 HeapWord* obj_top = new_obj + word_size;
331
332 // First, we need to zero the header of the space that we will be
333 // allocating. When we update top further down, some refinement
334 // threads might try to scan the region. By zeroing the header we
335 // ensure that any thread that will try to scan the region will
336 // come across the zero klass word and bail out.
337 //
338 // NOTE: It would not have been correct to have used
339 // CollectedHeap::fill_with_object() and make the space look like
340 // an int array. The thread that is doing the allocation will
341 // later update the object header to a potentially different array
342 // type and, for a very short period of time, the klass and length
343 // fields will be inconsistent. This could cause a refinement
344 // thread to calculate the object size incorrectly.
345 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
346
347 // How many words we use for filler objects.
348 size_t word_fill_size = word_size_sum - word_size;
349
350 // How many words memory we "waste" which cannot hold a filler object.
351 size_t words_not_fillable = 0;
352
353 if (word_fill_size >= min_fill_size()) {
354 fill_with_objects(obj_top, word_fill_size);
355 } else if (word_fill_size > 0) {
356 // We have space to fill, but we cannot fit an object there.
357 words_not_fillable = word_fill_size;
358 word_fill_size = 0;
359 }
360
361 // We will set up the first region as "starts humongous". This
362 // will also update the BOT covering all the regions to reflect
363 // that there is a single object that starts at the bottom of the
364 // first region.
365 first_hr->set_starts_humongous(obj_top, word_fill_size);
366 first_hr->set_allocation_context(context);
367 // Then, if there are any, we will set up the "continues
368 // humongous" regions.
369 HeapRegion* hr = NULL;
370 for (uint i = first + 1; i <= last; ++i) {
371 hr = region_at(i);
372 hr->set_continues_humongous(first_hr);
373 hr->set_allocation_context(context);
374 }
375
376 // Up to this point no concurrent thread would have been able to
377 // do any scanning on any region in this series. All the top
378 // fields still point to bottom, so the intersection between
379 // [bottom,top] and [card_start,card_end] will be empty. Before we
380 // update the top fields, we'll do a storestore to make sure that
381 // no thread sees the update to top before the zeroing of the
382 // object header and the BOT initialization.
383 OrderAccess::storestore();
384
385 // Now, we will update the top fields of the "continues humongous"
386 // regions except the last one.
387 for (uint i = first; i < last; ++i) {
388 hr = region_at(i);
389 hr->set_top(hr->end());
390 }
391
392 hr = region_at(last);
393 // If we cannot fit a filler object, we must set top to the end
394 // of the humongous object, otherwise we cannot iterate the heap
395 // and the BOT will not be complete.
396 hr->set_top(hr->end() - words_not_fillable);
397
398 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
399 "obj_top should be in last region");
400
401 check_bitmaps("Humongous Region Allocation", first_hr);
402
403 assert(words_not_fillable == 0 ||
404 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
405 "Miscalculation in humongous allocation");
406
407 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
408
409 for (uint i = first; i <= last; ++i) {
410 hr = region_at(i);
411 _humongous_set.add(hr);
412 if (i == first) {
413 _hr_printer.alloc(G1HRPrinter::StartsHumongous, hr, hr->top());
414 } else {
415 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->top());
416 }
417 }
418
419 return new_obj;
420 }
421
422 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
423 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
424 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
425 }
426
427 // If could fit into free regions w/o expansion, try.
428 // Otherwise, if can expand, do so.
429 // Otherwise, if using ex regions might help, try with ex given back.
430 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
431 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
432
433 verify_region_sets_optional();
434
435 uint first = G1_NO_HRM_INDEX;
436 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
437
438 if (obj_regions == 1) {
439 // Only one region to allocate, try to use a fast path by directly allocating
440 // from the free lists. Do not try to expand here, we will potentially do that
441 // later.
442 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
443 if (hr != NULL) {
444 first = hr->hrm_index();
445 }
446 } else {
447 // We can't allocate humongous regions spanning more than one region while
448 // cleanupComplete() is running, since some of the regions we find to be
449 // empty might not yet be added to the free list. It is not straightforward
450 // to know in which list they are on so that we can remove them. We only
451 // need to do this if we need to allocate more than one region to satisfy the
452 // current humongous allocation request. If we are only allocating one region
453 // we use the one-region region allocation code (see above), that already
454 // potentially waits for regions from the secondary free list.
455 wait_while_free_regions_coming();
456 append_secondary_free_list_if_not_empty_with_lock();
457
458 // Policy: Try only empty regions (i.e. already committed first). Maybe we
459 // are lucky enough to find some.
460 first = _hrm.find_contiguous_only_empty(obj_regions);
461 if (first != G1_NO_HRM_INDEX) {
462 _hrm.allocate_free_regions_starting_at(first, obj_regions);
463 }
464 }
465
466 if (first == G1_NO_HRM_INDEX) {
467 // Policy: We could not find enough regions for the humongous object in the
468 // free list. Look through the heap to find a mix of free and uncommitted regions.
469 // If so, try expansion.
470 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
471 if (first != G1_NO_HRM_INDEX) {
472 // We found something. Make sure these regions are committed, i.e. expand
473 // the heap. Alternatively we could do a defragmentation GC.
474 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
475 word_size * HeapWordSize);
476
477
478 _hrm.expand_at(first, obj_regions);
479 g1_policy()->record_new_heap_size(num_regions());
480
481 #ifdef ASSERT
482 for (uint i = first; i < first + obj_regions; ++i) {
483 HeapRegion* hr = region_at(i);
484 assert(hr->is_free(), "sanity");
485 assert(hr->is_empty(), "sanity");
486 assert(is_on_master_free_list(hr), "sanity");
487 }
488 #endif
489 _hrm.allocate_free_regions_starting_at(first, obj_regions);
490 } else {
491 // Policy: Potentially trigger a defragmentation GC.
492 }
493 }
494
495 HeapWord* result = NULL;
496 if (first != G1_NO_HRM_INDEX) {
497 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
498 word_size, context);
499 assert(result != NULL, "it should always return a valid result");
500
501 // A successful humongous object allocation changes the used space
502 // information of the old generation so we need to recalculate the
503 // sizes and update the jstat counters here.
504 g1mm()->update_sizes();
505 }
506
507 verify_region_sets_optional();
508
509 return result;
510 }
511
512 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
513 assert_heap_not_locked_and_not_at_safepoint();
514 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
515
516 uint dummy_gc_count_before;
517 uint dummy_gclocker_retry_count = 0;
518 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
519 }
520
521 HeapWord*
522 G1CollectedHeap::mem_allocate(size_t word_size,
523 bool* gc_overhead_limit_was_exceeded) {
524 assert_heap_not_locked_and_not_at_safepoint();
525
526 // Loop until the allocation is satisfied, or unsatisfied after GC.
527 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
528 uint gc_count_before;
529
530 HeapWord* result = NULL;
531 if (!is_humongous(word_size)) {
532 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
533 } else {
534 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
535 }
536 if (result != NULL) {
537 return result;
538 }
539
540 // Create the garbage collection operation...
541 VM_G1CollectForAllocation op(gc_count_before, word_size);
542 op.set_allocation_context(AllocationContext::current());
543
544 // ...and get the VM thread to execute it.
545 VMThread::execute(&op);
546
547 if (op.prologue_succeeded() && op.pause_succeeded()) {
548 // If the operation was successful we'll return the result even
549 // if it is NULL. If the allocation attempt failed immediately
550 // after a Full GC, it's unlikely we'll be able to allocate now.
551 HeapWord* result = op.result();
552 if (result != NULL && !is_humongous(word_size)) {
553 // Allocations that take place on VM operations do not do any
554 // card dirtying and we have to do it here. We only have to do
555 // this for non-humongous allocations, though.
556 dirty_young_block(result, word_size);
557 }
558 return result;
559 } else {
560 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
561 return NULL;
562 }
563 assert(op.result() == NULL,
564 "the result should be NULL if the VM op did not succeed");
565 }
566
567 // Give a warning if we seem to be looping forever.
568 if ((QueuedAllocationWarningCount > 0) &&
569 (try_count % QueuedAllocationWarningCount == 0)) {
570 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
571 }
572 }
573
574 ShouldNotReachHere();
575 return NULL;
576 }
577
578 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
579 AllocationContext_t context,
580 uint* gc_count_before_ret,
581 uint* gclocker_retry_count_ret) {
582 // Make sure you read the note in attempt_allocation_humongous().
583
584 assert_heap_not_locked_and_not_at_safepoint();
585 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
586 "be called for humongous allocation requests");
587
588 // We should only get here after the first-level allocation attempt
589 // (attempt_allocation()) failed to allocate.
590
591 // We will loop until a) we manage to successfully perform the
592 // allocation or b) we successfully schedule a collection which
593 // fails to perform the allocation. b) is the only case when we'll
594 // return NULL.
595 HeapWord* result = NULL;
596 for (int try_count = 1; /* we'll return */; try_count += 1) {
597 bool should_try_gc;
598 uint gc_count_before;
599
600 {
601 MutexLockerEx x(Heap_lock);
602 result = _allocator->attempt_allocation_locked(word_size, context);
603 if (result != NULL) {
604 return result;
605 }
606
607 if (GC_locker::is_active_and_needs_gc()) {
608 if (g1_policy()->can_expand_young_list()) {
609 // No need for an ergo verbose message here,
610 // can_expand_young_list() does this when it returns true.
611 result = _allocator->attempt_allocation_force(word_size, context);
612 if (result != NULL) {
613 return result;
614 }
615 }
616 should_try_gc = false;
617 } else {
618 // The GCLocker may not be active but the GCLocker initiated
619 // GC may not yet have been performed (GCLocker::needs_gc()
620 // returns true). In this case we do not try this GC and
621 // wait until the GCLocker initiated GC is performed, and
622 // then retry the allocation.
623 if (GC_locker::needs_gc()) {
624 should_try_gc = false;
625 } else {
626 // Read the GC count while still holding the Heap_lock.
627 gc_count_before = total_collections();
628 should_try_gc = true;
629 }
630 }
631 }
632
633 if (should_try_gc) {
634 bool succeeded;
635 result = do_collection_pause(word_size, gc_count_before, &succeeded,
636 GCCause::_g1_inc_collection_pause);
637 if (result != NULL) {
638 assert(succeeded, "only way to get back a non-NULL result");
639 return result;
640 }
641
642 if (succeeded) {
643 // If we get here we successfully scheduled a collection which
644 // failed to allocate. No point in trying to allocate
645 // further. We'll just return NULL.
646 MutexLockerEx x(Heap_lock);
647 *gc_count_before_ret = total_collections();
648 return NULL;
649 }
650 } else {
651 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
652 MutexLockerEx x(Heap_lock);
653 *gc_count_before_ret = total_collections();
654 return NULL;
655 }
656 // The GCLocker is either active or the GCLocker initiated
657 // GC has not yet been performed. Stall until it is and
658 // then retry the allocation.
659 GC_locker::stall_until_clear();
660 (*gclocker_retry_count_ret) += 1;
661 }
662
663 // We can reach here if we were unsuccessful in scheduling a
664 // collection (because another thread beat us to it) or if we were
665 // stalled due to the GC locker. In either can we should retry the
666 // allocation attempt in case another thread successfully
667 // performed a collection and reclaimed enough space. We do the
668 // first attempt (without holding the Heap_lock) here and the
669 // follow-on attempt will be at the start of the next loop
670 // iteration (after taking the Heap_lock).
671 result = _allocator->attempt_allocation(word_size, context);
672 if (result != NULL) {
673 return result;
674 }
675
676 // Give a warning if we seem to be looping forever.
677 if ((QueuedAllocationWarningCount > 0) &&
678 (try_count % QueuedAllocationWarningCount == 0)) {
679 warning("G1CollectedHeap::attempt_allocation_slow() "
680 "retries %d times", try_count);
681 }
682 }
683
684 ShouldNotReachHere();
685 return NULL;
686 }
687
688 void G1CollectedHeap::begin_archive_alloc_range() {
689 assert_at_safepoint(true /* should_be_vm_thread */);
690 if (_archive_allocator == NULL) {
691 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
692 }
693 }
694
695 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
696 // Allocations in archive regions cannot be of a size that would be considered
697 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
698 // may be different at archive-restore time.
699 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
700 }
701
702 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
703 assert_at_safepoint(true /* should_be_vm_thread */);
704 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
705 if (is_archive_alloc_too_large(word_size)) {
706 return NULL;
707 }
708 return _archive_allocator->archive_mem_allocate(word_size);
709 }
710
711 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
712 size_t end_alignment_in_bytes) {
713 assert_at_safepoint(true /* should_be_vm_thread */);
714 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
715
716 // Call complete_archive to do the real work, filling in the MemRegion
717 // array with the archive regions.
718 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
719 delete _archive_allocator;
720 _archive_allocator = NULL;
721 }
722
723 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
724 assert(ranges != NULL, "MemRegion array NULL");
725 assert(count != 0, "No MemRegions provided");
726 MemRegion reserved = _hrm.reserved();
727 for (size_t i = 0; i < count; i++) {
728 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
729 return false;
730 }
731 }
732 return true;
733 }
734
735 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
736 assert(!is_init_completed(), "Expect to be called at JVM init time");
737 assert(ranges != NULL, "MemRegion array NULL");
738 assert(count != 0, "No MemRegions provided");
739 MutexLockerEx x(Heap_lock);
740
741 MemRegion reserved = _hrm.reserved();
742 HeapWord* prev_last_addr = NULL;
743 HeapRegion* prev_last_region = NULL;
744
745 // Temporarily disable pretouching of heap pages. This interface is used
746 // when mmap'ing archived heap data in, so pre-touching is wasted.
747 FlagSetting fs(AlwaysPreTouch, false);
748
749 // Enable archive object checking in G1MarkSweep. We have to let it know
750 // about each archive range, so that objects in those ranges aren't marked.
751 G1MarkSweep::enable_archive_object_check();
752
753 // For each specified MemRegion range, allocate the corresponding G1
754 // regions and mark them as archive regions. We expect the ranges in
755 // ascending starting address order, without overlap.
756 for (size_t i = 0; i < count; i++) {
757 MemRegion curr_range = ranges[i];
758 HeapWord* start_address = curr_range.start();
759 size_t word_size = curr_range.word_size();
760 HeapWord* last_address = curr_range.last();
761 size_t commits = 0;
762
763 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
764 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
765 p2i(start_address), p2i(last_address));
766 guarantee(start_address > prev_last_addr,
767 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
768 p2i(start_address), p2i(prev_last_addr));
769 prev_last_addr = last_address;
770
771 // Check for ranges that start in the same G1 region in which the previous
772 // range ended, and adjust the start address so we don't try to allocate
773 // the same region again. If the current range is entirely within that
774 // region, skip it, just adjusting the recorded top.
775 HeapRegion* start_region = _hrm.addr_to_region(start_address);
776 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
777 start_address = start_region->end();
778 if (start_address > last_address) {
779 increase_used(word_size * HeapWordSize);
780 start_region->set_top(last_address + 1);
781 continue;
782 }
783 start_region->set_top(start_address);
784 curr_range = MemRegion(start_address, last_address + 1);
785 start_region = _hrm.addr_to_region(start_address);
786 }
787
788 // Perform the actual region allocation, exiting if it fails.
789 // Then note how much new space we have allocated.
790 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
791 return false;
792 }
793 increase_used(word_size * HeapWordSize);
794 if (commits != 0) {
795 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
796 HeapRegion::GrainWords * HeapWordSize * commits);
797
798 }
799
800 // Mark each G1 region touched by the range as archive, add it to the old set,
801 // and set the allocation context and top.
802 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
803 HeapRegion* last_region = _hrm.addr_to_region(last_address);
804 prev_last_region = last_region;
805
806 while (curr_region != NULL) {
807 assert(curr_region->is_empty() && !curr_region->is_pinned(),
808 "Region already in use (index %u)", curr_region->hrm_index());
809 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
810 curr_region->set_allocation_context(AllocationContext::system());
811 curr_region->set_archive();
812 _old_set.add(curr_region);
813 if (curr_region != last_region) {
814 curr_region->set_top(curr_region->end());
815 curr_region = _hrm.next_region_in_heap(curr_region);
816 } else {
817 curr_region->set_top(last_address + 1);
818 curr_region = NULL;
819 }
820 }
821
822 // Notify mark-sweep of the archive range.
823 G1MarkSweep::set_range_archive(curr_range, true);
824 }
825 return true;
826 }
827
828 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
829 assert(!is_init_completed(), "Expect to be called at JVM init time");
830 assert(ranges != NULL, "MemRegion array NULL");
831 assert(count != 0, "No MemRegions provided");
832 MemRegion reserved = _hrm.reserved();
833 HeapWord *prev_last_addr = NULL;
834 HeapRegion* prev_last_region = NULL;
835
836 // For each MemRegion, create filler objects, if needed, in the G1 regions
837 // that contain the address range. The address range actually within the
838 // MemRegion will not be modified. That is assumed to have been initialized
839 // elsewhere, probably via an mmap of archived heap data.
840 MutexLockerEx x(Heap_lock);
841 for (size_t i = 0; i < count; i++) {
842 HeapWord* start_address = ranges[i].start();
843 HeapWord* last_address = ranges[i].last();
844
845 assert(reserved.contains(start_address) && reserved.contains(last_address),
846 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
847 p2i(start_address), p2i(last_address));
848 assert(start_address > prev_last_addr,
849 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
850 p2i(start_address), p2i(prev_last_addr));
851
852 HeapRegion* start_region = _hrm.addr_to_region(start_address);
853 HeapRegion* last_region = _hrm.addr_to_region(last_address);
854 HeapWord* bottom_address = start_region->bottom();
855
856 // Check for a range beginning in the same region in which the
857 // previous one ended.
858 if (start_region == prev_last_region) {
859 bottom_address = prev_last_addr + 1;
860 }
861
862 // Verify that the regions were all marked as archive regions by
863 // alloc_archive_regions.
864 HeapRegion* curr_region = start_region;
865 while (curr_region != NULL) {
866 guarantee(curr_region->is_archive(),
867 "Expected archive region at index %u", curr_region->hrm_index());
868 if (curr_region != last_region) {
869 curr_region = _hrm.next_region_in_heap(curr_region);
870 } else {
871 curr_region = NULL;
872 }
873 }
874
875 prev_last_addr = last_address;
876 prev_last_region = last_region;
877
878 // Fill the memory below the allocated range with dummy object(s),
879 // if the region bottom does not match the range start, or if the previous
880 // range ended within the same G1 region, and there is a gap.
881 if (start_address != bottom_address) {
882 size_t fill_size = pointer_delta(start_address, bottom_address);
883 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
884 increase_used(fill_size * HeapWordSize);
885 }
886 }
887 }
888
889 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
890 uint* gc_count_before_ret,
891 uint* gclocker_retry_count_ret) {
892 assert_heap_not_locked_and_not_at_safepoint();
893 assert(!is_humongous(word_size), "attempt_allocation() should not "
894 "be called for humongous allocation requests");
895
896 AllocationContext_t context = AllocationContext::current();
897 HeapWord* result = _allocator->attempt_allocation(word_size, context);
898
899 if (result == NULL) {
900 result = attempt_allocation_slow(word_size,
901 context,
902 gc_count_before_ret,
903 gclocker_retry_count_ret);
904 }
905 assert_heap_not_locked();
906 if (result != NULL) {
907 dirty_young_block(result, word_size);
908 }
909 return result;
910 }
911
912 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
913 assert(!is_init_completed(), "Expect to be called at JVM init time");
914 assert(ranges != NULL, "MemRegion array NULL");
915 assert(count != 0, "No MemRegions provided");
916 MemRegion reserved = _hrm.reserved();
917 HeapWord* prev_last_addr = NULL;
918 HeapRegion* prev_last_region = NULL;
919 size_t size_used = 0;
920 size_t uncommitted_regions = 0;
921
922 // For each Memregion, free the G1 regions that constitute it, and
923 // notify mark-sweep that the range is no longer to be considered 'archive.'
924 MutexLockerEx x(Heap_lock);
925 for (size_t i = 0; i < count; i++) {
926 HeapWord* start_address = ranges[i].start();
927 HeapWord* last_address = ranges[i].last();
928
929 assert(reserved.contains(start_address) && reserved.contains(last_address),
930 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
931 p2i(start_address), p2i(last_address));
932 assert(start_address > prev_last_addr,
933 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
934 p2i(start_address), p2i(prev_last_addr));
935 size_used += ranges[i].byte_size();
936 prev_last_addr = last_address;
937
938 HeapRegion* start_region = _hrm.addr_to_region(start_address);
939 HeapRegion* last_region = _hrm.addr_to_region(last_address);
940
941 // Check for ranges that start in the same G1 region in which the previous
942 // range ended, and adjust the start address so we don't try to free
943 // the same region again. If the current range is entirely within that
944 // region, skip it.
945 if (start_region == prev_last_region) {
946 start_address = start_region->end();
947 if (start_address > last_address) {
948 continue;
949 }
950 start_region = _hrm.addr_to_region(start_address);
951 }
952 prev_last_region = last_region;
953
954 // After verifying that each region was marked as an archive region by
955 // alloc_archive_regions, set it free and empty and uncommit it.
956 HeapRegion* curr_region = start_region;
957 while (curr_region != NULL) {
958 guarantee(curr_region->is_archive(),
959 "Expected archive region at index %u", curr_region->hrm_index());
960 uint curr_index = curr_region->hrm_index();
961 _old_set.remove(curr_region);
962 curr_region->set_free();
963 curr_region->set_top(curr_region->bottom());
964 if (curr_region != last_region) {
965 curr_region = _hrm.next_region_in_heap(curr_region);
966 } else {
967 curr_region = NULL;
968 }
969 _hrm.shrink_at(curr_index, 1);
970 uncommitted_regions++;
971 }
972
973 // Notify mark-sweep that this is no longer an archive range.
974 G1MarkSweep::set_range_archive(ranges[i], false);
975 }
976
977 if (uncommitted_regions != 0) {
978 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
979 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
980 }
981 decrease_used(size_used);
982 }
983
984 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
985 uint* gc_count_before_ret,
986 uint* gclocker_retry_count_ret) {
987 // The structure of this method has a lot of similarities to
988 // attempt_allocation_slow(). The reason these two were not merged
989 // into a single one is that such a method would require several "if
990 // allocation is not humongous do this, otherwise do that"
991 // conditional paths which would obscure its flow. In fact, an early
992 // version of this code did use a unified method which was harder to
993 // follow and, as a result, it had subtle bugs that were hard to
994 // track down. So keeping these two methods separate allows each to
995 // be more readable. It will be good to keep these two in sync as
996 // much as possible.
997
998 assert_heap_not_locked_and_not_at_safepoint();
999 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1000 "should only be called for humongous allocations");
1001
1002 // Humongous objects can exhaust the heap quickly, so we should check if we
1003 // need to start a marking cycle at each humongous object allocation. We do
1004 // the check before we do the actual allocation. The reason for doing it
1005 // before the allocation is that we avoid having to keep track of the newly
1006 // allocated memory while we do a GC.
1007 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1008 word_size)) {
1009 collect(GCCause::_g1_humongous_allocation);
1010 }
1011
1012 // We will loop until a) we manage to successfully perform the
1013 // allocation or b) we successfully schedule a collection which
1014 // fails to perform the allocation. b) is the only case when we'll
1015 // return NULL.
1016 HeapWord* result = NULL;
1017 for (int try_count = 1; /* we'll return */; try_count += 1) {
1018 bool should_try_gc;
1019 uint gc_count_before;
1020
1021 {
1022 MutexLockerEx x(Heap_lock);
1023
1024 // Given that humongous objects are not allocated in young
1025 // regions, we'll first try to do the allocation without doing a
1026 // collection hoping that there's enough space in the heap.
1027 result = humongous_obj_allocate(word_size, AllocationContext::current());
1028 if (result != NULL) {
1029 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1030 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1031 return result;
1032 }
1033
1034 if (GC_locker::is_active_and_needs_gc()) {
1035 should_try_gc = false;
1036 } else {
1037 // The GCLocker may not be active but the GCLocker initiated
1038 // GC may not yet have been performed (GCLocker::needs_gc()
1039 // returns true). In this case we do not try this GC and
1040 // wait until the GCLocker initiated GC is performed, and
1041 // then retry the allocation.
1042 if (GC_locker::needs_gc()) {
1043 should_try_gc = false;
1044 } else {
1045 // Read the GC count while still holding the Heap_lock.
1046 gc_count_before = total_collections();
1047 should_try_gc = true;
1048 }
1049 }
1050 }
1051
1052 if (should_try_gc) {
1053 // If we failed to allocate the humongous object, we should try to
1054 // do a collection pause (if we're allowed) in case it reclaims
1055 // enough space for the allocation to succeed after the pause.
1056
1057 bool succeeded;
1058 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1059 GCCause::_g1_humongous_allocation);
1060 if (result != NULL) {
1061 assert(succeeded, "only way to get back a non-NULL result");
1062 return result;
1063 }
1064
1065 if (succeeded) {
1066 // If we get here we successfully scheduled a collection which
1067 // failed to allocate. No point in trying to allocate
1068 // further. We'll just return NULL.
1069 MutexLockerEx x(Heap_lock);
1070 *gc_count_before_ret = total_collections();
1071 return NULL;
1072 }
1073 } else {
1074 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1075 MutexLockerEx x(Heap_lock);
1076 *gc_count_before_ret = total_collections();
1077 return NULL;
1078 }
1079 // The GCLocker is either active or the GCLocker initiated
1080 // GC has not yet been performed. Stall until it is and
1081 // then retry the allocation.
1082 GC_locker::stall_until_clear();
1083 (*gclocker_retry_count_ret) += 1;
1084 }
1085
1086 // We can reach here if we were unsuccessful in scheduling a
1087 // collection (because another thread beat us to it) or if we were
1088 // stalled due to the GC locker. In either can we should retry the
1089 // allocation attempt in case another thread successfully
1090 // performed a collection and reclaimed enough space. Give a
1091 // warning if we seem to be looping forever.
1092
1093 if ((QueuedAllocationWarningCount > 0) &&
1094 (try_count % QueuedAllocationWarningCount == 0)) {
1095 warning("G1CollectedHeap::attempt_allocation_humongous() "
1096 "retries %d times", try_count);
1097 }
1098 }
1099
1100 ShouldNotReachHere();
1101 return NULL;
1102 }
1103
1104 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1105 AllocationContext_t context,
1106 bool expect_null_mutator_alloc_region) {
1107 assert_at_safepoint(true /* should_be_vm_thread */);
1108 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1109 "the current alloc region was unexpectedly found to be non-NULL");
1110
1111 if (!is_humongous(word_size)) {
1112 return _allocator->attempt_allocation_locked(word_size, context);
1113 } else {
1114 HeapWord* result = humongous_obj_allocate(word_size, context);
1115 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1116 collector_state()->set_initiate_conc_mark_if_possible(true);
1117 }
1118 return result;
1119 }
1120
1121 ShouldNotReachHere();
1122 }
1123
1124 class PostMCRemSetClearClosure: public HeapRegionClosure {
1125 G1CollectedHeap* _g1h;
1126 ModRefBarrierSet* _mr_bs;
1127 public:
1128 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1129 _g1h(g1h), _mr_bs(mr_bs) {}
1130
1131 bool doHeapRegion(HeapRegion* r) {
1132 HeapRegionRemSet* hrrs = r->rem_set();
1133
1134 _g1h->reset_gc_time_stamps(r);
1135
1136 if (r->is_continues_humongous()) {
1137 // We'll assert that the strong code root list and RSet is empty
1138 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1139 assert(hrrs->occupied() == 0, "RSet should be empty");
1140 } else {
1141 hrrs->clear();
1142 }
1143 // You might think here that we could clear just the cards
1144 // corresponding to the used region. But no: if we leave a dirty card
1145 // in a region we might allocate into, then it would prevent that card
1146 // from being enqueued, and cause it to be missed.
1147 // Re: the performance cost: we shouldn't be doing full GC anyway!
1148 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1149
1150 return false;
1151 }
1152 };
1153
1154 void G1CollectedHeap::clear_rsets_post_compaction() {
1155 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1156 heap_region_iterate(&rs_clear);
1157 }
1158
1159 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1160 G1CollectedHeap* _g1h;
1161 UpdateRSOopClosure _cl;
1162 public:
1163 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1164 _cl(g1->g1_rem_set(), worker_i),
1165 _g1h(g1)
1166 { }
1167
1168 bool doHeapRegion(HeapRegion* r) {
1169 if (!r->is_continues_humongous()) {
1170 _cl.set_from(r);
1171 r->oop_iterate(&_cl);
1172 }
1173 return false;
1174 }
1175 };
1176
1177 class ParRebuildRSTask: public AbstractGangTask {
1178 G1CollectedHeap* _g1;
1179 HeapRegionClaimer _hrclaimer;
1180
1181 public:
1182 ParRebuildRSTask(G1CollectedHeap* g1) :
1183 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1184
1185 void work(uint worker_id) {
1186 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1187 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1188 }
1189 };
1190
1191 class PostCompactionPrinterClosure: public HeapRegionClosure {
1192 private:
1193 G1HRPrinter* _hr_printer;
1194 public:
1195 bool doHeapRegion(HeapRegion* hr) {
1196 assert(!hr->is_young(), "not expecting to find young regions");
1197 if (hr->is_free()) {
1198 // We only generate output for non-empty regions.
1199 } else if (hr->is_starts_humongous()) {
1200 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1201 } else if (hr->is_continues_humongous()) {
1202 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1203 } else if (hr->is_archive()) {
1204 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1205 } else if (hr->is_old()) {
1206 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1207 } else {
1208 ShouldNotReachHere();
1209 }
1210 return false;
1211 }
1212
1213 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1214 : _hr_printer(hr_printer) { }
1215 };
1216
1217 void G1CollectedHeap::print_hrm_post_compaction() {
1218 if (_hr_printer.is_active()) {
1219 PostCompactionPrinterClosure cl(hr_printer());
1220 heap_region_iterate(&cl);
1221 }
1222
1223 }
1224
1225 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1226 bool clear_all_soft_refs) {
1227 assert_at_safepoint(true /* should_be_vm_thread */);
1228
1229 if (GC_locker::check_active_before_gc()) {
1230 return false;
1231 }
1232
1233 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1234 gc_timer->register_gc_start();
1235
1236 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1237 GCIdMark gc_id_mark;
1238 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1239
1240 SvcGCMarker sgcm(SvcGCMarker::FULL);
1241 ResourceMark rm;
1242
1243 print_heap_before_gc();
1244 trace_heap_before_gc(gc_tracer);
1245
1246 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1247
1248 verify_region_sets_optional();
1249
1250 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1251 collector_policy()->should_clear_all_soft_refs();
1252
1253 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1254
1255 {
1256 IsGCActiveMark x;
1257
1258 // Timing
1259 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1260 GCTraceCPUTime tcpu;
1261
1262 {
1263 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1264 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1265 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1266
1267 g1_policy()->record_full_collection_start();
1268
1269 // Note: When we have a more flexible GC logging framework that
1270 // allows us to add optional attributes to a GC log record we
1271 // could consider timing and reporting how long we wait in the
1272 // following two methods.
1273 wait_while_free_regions_coming();
1274 // If we start the compaction before the CM threads finish
1275 // scanning the root regions we might trip them over as we'll
1276 // be moving objects / updating references. So let's wait until
1277 // they are done. By telling them to abort, they should complete
1278 // early.
1279 _cm->root_regions()->abort();
1280 _cm->root_regions()->wait_until_scan_finished();
1281 append_secondary_free_list_if_not_empty_with_lock();
1282
1283 gc_prologue(true);
1284 increment_total_collections(true /* full gc */);
1285 increment_old_marking_cycles_started();
1286
1287 assert(used() == recalculate_used(), "Should be equal");
1288
1289 verify_before_gc();
1290
1291 check_bitmaps("Full GC Start");
1292 pre_full_gc_dump(gc_timer);
1293
1294 #if defined(COMPILER2) || INCLUDE_JVMCI
1295 DerivedPointerTable::clear();
1296 #endif
1297
1298 // Disable discovery and empty the discovered lists
1299 // for the CM ref processor.
1300 ref_processor_cm()->disable_discovery();
1301 ref_processor_cm()->abandon_partial_discovery();
1302 ref_processor_cm()->verify_no_references_recorded();
1303
1304 // Abandon current iterations of concurrent marking and concurrent
1305 // refinement, if any are in progress. We have to do this before
1306 // wait_until_scan_finished() below.
1307 concurrent_mark()->abort();
1308
1309 // Make sure we'll choose a new allocation region afterwards.
1310 _allocator->release_mutator_alloc_region();
1311 _allocator->abandon_gc_alloc_regions();
1312 g1_rem_set()->cleanupHRRS();
1313
1314 // We may have added regions to the current incremental collection
1315 // set between the last GC or pause and now. We need to clear the
1316 // incremental collection set and then start rebuilding it afresh
1317 // after this full GC.
1318 abandon_collection_set(g1_policy()->inc_cset_head());
1319 g1_policy()->clear_incremental_cset();
1320 g1_policy()->stop_incremental_cset_building();
1321
1322 tear_down_region_sets(false /* free_list_only */);
1323 collector_state()->set_gcs_are_young(true);
1324
1325 // See the comments in g1CollectedHeap.hpp and
1326 // G1CollectedHeap::ref_processing_init() about
1327 // how reference processing currently works in G1.
1328
1329 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1330 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1331
1332 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1333 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1334
1335 ref_processor_stw()->enable_discovery();
1336 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1337
1338 // Do collection work
1339 {
1340 HandleMark hm; // Discard invalid handles created during gc
1341 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1342 }
1343
1344 assert(num_free_regions() == 0, "we should not have added any free regions");
1345 rebuild_region_sets(false /* free_list_only */);
1346
1347 // Enqueue any discovered reference objects that have
1348 // not been removed from the discovered lists.
1349 ref_processor_stw()->enqueue_discovered_references();
1350
1351 #if defined(COMPILER2) || INCLUDE_JVMCI
1352 DerivedPointerTable::update_pointers();
1353 #endif
1354
1355 MemoryService::track_memory_usage();
1356
1357 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1358 ref_processor_stw()->verify_no_references_recorded();
1359
1360 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1361 ClassLoaderDataGraph::purge();
1362 MetaspaceAux::verify_metrics();
1363
1364 // Note: since we've just done a full GC, concurrent
1365 // marking is no longer active. Therefore we need not
1366 // re-enable reference discovery for the CM ref processor.
1367 // That will be done at the start of the next marking cycle.
1368 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1369 ref_processor_cm()->verify_no_references_recorded();
1370
1371 reset_gc_time_stamp();
1372 // Since everything potentially moved, we will clear all remembered
1373 // sets, and clear all cards. Later we will rebuild remembered
1374 // sets. We will also reset the GC time stamps of the regions.
1375 clear_rsets_post_compaction();
1376 check_gc_time_stamps();
1377
1378 resize_if_necessary_after_full_collection();
1379
1380 // We should do this after we potentially resize the heap so
1381 // that all the COMMIT / UNCOMMIT events are generated before
1382 // the compaction events.
1383 print_hrm_post_compaction();
1384
1385 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1386 if (hot_card_cache->use_cache()) {
1387 hot_card_cache->reset_card_counts();
1388 hot_card_cache->reset_hot_cache();
1389 }
1390
1391 // Rebuild remembered sets of all regions.
1392 uint n_workers =
1393 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1394 workers()->active_workers(),
1395 Threads::number_of_non_daemon_threads());
1396 workers()->set_active_workers(n_workers);
1397
1398 ParRebuildRSTask rebuild_rs_task(this);
1399 workers()->run_task(&rebuild_rs_task);
1400
1401 // Rebuild the strong code root lists for each region
1402 rebuild_strong_code_roots();
1403
1404 if (true) { // FIXME
1405 MetaspaceGC::compute_new_size();
1406 }
1407
1408 #ifdef TRACESPINNING
1409 ParallelTaskTerminator::print_termination_counts();
1410 #endif
1411
1412 // Discard all rset updates
1413 JavaThread::dirty_card_queue_set().abandon_logs();
1414 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1415
1416 _young_list->reset_sampled_info();
1417 // At this point there should be no regions in the
1418 // entire heap tagged as young.
1419 assert(check_young_list_empty(true /* check_heap */),
1420 "young list should be empty at this point");
1421
1422 // Update the number of full collections that have been completed.
1423 increment_old_marking_cycles_completed(false /* concurrent */);
1424
1425 _hrm.verify_optional();
1426 verify_region_sets_optional();
1427
1428 verify_after_gc();
1429
1430 // Clear the previous marking bitmap, if needed for bitmap verification.
1431 // Note we cannot do this when we clear the next marking bitmap in
1432 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1433 // objects marked during a full GC against the previous bitmap.
1434 // But we need to clear it before calling check_bitmaps below since
1435 // the full GC has compacted objects and updated TAMS but not updated
1436 // the prev bitmap.
1437 if (G1VerifyBitmaps) {
1438 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1439 }
1440 check_bitmaps("Full GC End");
1441
1442 // Start a new incremental collection set for the next pause
1443 assert(g1_policy()->collection_set() == NULL, "must be");
1444 g1_policy()->start_incremental_cset_building();
1445
1446 clear_cset_fast_test();
1447
1448 _allocator->init_mutator_alloc_region();
1449
1450 g1_policy()->record_full_collection_end();
1451
1452 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1453 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1454 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1455 // before any GC notifications are raised.
1456 g1mm()->update_sizes();
1457
1458 gc_epilogue(true);
1459 }
1460
1461 g1_policy()->print_detailed_heap_transition();
1462
1463 print_heap_after_gc();
1464 trace_heap_after_gc(gc_tracer);
1465
1466 post_full_gc_dump(gc_timer);
1467
1468 gc_timer->register_gc_end();
1469 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1470 }
1471
1472 return true;
1473 }
1474
1475 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1476 // Currently, there is no facility in the do_full_collection(bool) API to notify
1477 // the caller that the collection did not succeed (e.g., because it was locked
1478 // out by the GC locker). So, right now, we'll ignore the return value.
1479 bool dummy = do_full_collection(true, /* explicit_gc */
1480 clear_all_soft_refs);
1481 }
1482
1483 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1484 // Include bytes that will be pre-allocated to support collections, as "used".
1485 const size_t used_after_gc = used();
1486 const size_t capacity_after_gc = capacity();
1487 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1488
1489 // This is enforced in arguments.cpp.
1490 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1491 "otherwise the code below doesn't make sense");
1492
1493 // We don't have floating point command-line arguments
1494 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1495 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1496 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1497 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1498
1499 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1500 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1501
1502 // We have to be careful here as these two calculations can overflow
1503 // 32-bit size_t's.
1504 double used_after_gc_d = (double) used_after_gc;
1505 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1506 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1507
1508 // Let's make sure that they are both under the max heap size, which
1509 // by default will make them fit into a size_t.
1510 double desired_capacity_upper_bound = (double) max_heap_size;
1511 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1512 desired_capacity_upper_bound);
1513 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1514 desired_capacity_upper_bound);
1515
1516 // We can now safely turn them into size_t's.
1517 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1518 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1519
1520 // This assert only makes sense here, before we adjust them
1521 // with respect to the min and max heap size.
1522 assert(minimum_desired_capacity <= maximum_desired_capacity,
1523 "minimum_desired_capacity = " SIZE_FORMAT ", "
1524 "maximum_desired_capacity = " SIZE_FORMAT,
1525 minimum_desired_capacity, maximum_desired_capacity);
1526
1527 // Should not be greater than the heap max size. No need to adjust
1528 // it with respect to the heap min size as it's a lower bound (i.e.,
1529 // we'll try to make the capacity larger than it, not smaller).
1530 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1531 // Should not be less than the heap min size. No need to adjust it
1532 // with respect to the heap max size as it's an upper bound (i.e.,
1533 // we'll try to make the capacity smaller than it, not greater).
1534 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1535
1536 if (capacity_after_gc < minimum_desired_capacity) {
1537 // Don't expand unless it's significant
1538 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1539
1540 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1541 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1542 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1543
1544 expand(expand_bytes);
1545
1546 // No expansion, now see if we want to shrink
1547 } else if (capacity_after_gc > maximum_desired_capacity) {
1548 // Capacity too large, compute shrinking size
1549 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1550
1551 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1552 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1553 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1554
1555 shrink(shrink_bytes);
1556 }
1557 }
1558
1559 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1560 AllocationContext_t context,
1561 bool do_gc,
1562 bool clear_all_soft_refs,
1563 bool expect_null_mutator_alloc_region,
1564 bool* gc_succeeded) {
1565 *gc_succeeded = true;
1566 // Let's attempt the allocation first.
1567 HeapWord* result =
1568 attempt_allocation_at_safepoint(word_size,
1569 context,
1570 expect_null_mutator_alloc_region);
1571 if (result != NULL) {
1572 assert(*gc_succeeded, "sanity");
1573 return result;
1574 }
1575
1576 // In a G1 heap, we're supposed to keep allocation from failing by
1577 // incremental pauses. Therefore, at least for now, we'll favor
1578 // expansion over collection. (This might change in the future if we can
1579 // do something smarter than full collection to satisfy a failed alloc.)
1580 result = expand_and_allocate(word_size, context);
1581 if (result != NULL) {
1582 assert(*gc_succeeded, "sanity");
1583 return result;
1584 }
1585
1586 if (do_gc) {
1587 // Expansion didn't work, we'll try to do a Full GC.
1588 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1589 clear_all_soft_refs);
1590 }
1591
1592 return NULL;
1593 }
1594
1595 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1596 AllocationContext_t context,
1597 bool* succeeded) {
1598 assert_at_safepoint(true /* should_be_vm_thread */);
1599
1600 // Attempts to allocate followed by Full GC.
1601 HeapWord* result =
1602 satisfy_failed_allocation_helper(word_size,
1603 context,
1604 true, /* do_gc */
1605 false, /* clear_all_soft_refs */
1606 false, /* expect_null_mutator_alloc_region */
1607 succeeded);
1608
1609 if (result != NULL || !*succeeded) {
1610 return result;
1611 }
1612
1613 // Attempts to allocate followed by Full GC that will collect all soft references.
1614 result = satisfy_failed_allocation_helper(word_size,
1615 context,
1616 true, /* do_gc */
1617 true, /* clear_all_soft_refs */
1618 true, /* expect_null_mutator_alloc_region */
1619 succeeded);
1620
1621 if (result != NULL || !*succeeded) {
1622 return result;
1623 }
1624
1625 // Attempts to allocate, no GC
1626 result = satisfy_failed_allocation_helper(word_size,
1627 context,
1628 false, /* do_gc */
1629 false, /* clear_all_soft_refs */
1630 true, /* expect_null_mutator_alloc_region */
1631 succeeded);
1632
1633 if (result != NULL) {
1634 assert(*succeeded, "sanity");
1635 return result;
1636 }
1637
1638 assert(!collector_policy()->should_clear_all_soft_refs(),
1639 "Flag should have been handled and cleared prior to this point");
1640
1641 // What else? We might try synchronous finalization later. If the total
1642 // space available is large enough for the allocation, then a more
1643 // complete compaction phase than we've tried so far might be
1644 // appropriate.
1645 assert(*succeeded, "sanity");
1646 return NULL;
1647 }
1648
1649 // Attempting to expand the heap sufficiently
1650 // to support an allocation of the given "word_size". If
1651 // successful, perform the allocation and return the address of the
1652 // allocated block, or else "NULL".
1653
1654 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1655 assert_at_safepoint(true /* should_be_vm_thread */);
1656
1657 verify_region_sets_optional();
1658
1659 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1660 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1661 word_size * HeapWordSize);
1662
1663
1664 if (expand(expand_bytes)) {
1665 _hrm.verify_optional();
1666 verify_region_sets_optional();
1667 return attempt_allocation_at_safepoint(word_size,
1668 context,
1669 false /* expect_null_mutator_alloc_region */);
1670 }
1671 return NULL;
1672 }
1673
1674 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1675 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1676 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1677 HeapRegion::GrainBytes);
1678
1679 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1680 expand_bytes, aligned_expand_bytes);
1681
1682 if (is_maximal_no_gc()) {
1683 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1684 return false;
1685 }
1686
1687 double expand_heap_start_time_sec = os::elapsedTime();
1688 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1689 assert(regions_to_expand > 0, "Must expand by at least one region");
1690
1691 uint expanded_by = _hrm.expand_by(regions_to_expand);
1692 if (expand_time_ms != NULL) {
1693 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1694 }
1695
1696 if (expanded_by > 0) {
1697 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1698 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1699 g1_policy()->record_new_heap_size(num_regions());
1700 } else {
1701 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1702
1703 // The expansion of the virtual storage space was unsuccessful.
1704 // Let's see if it was because we ran out of swap.
1705 if (G1ExitOnExpansionFailure &&
1706 _hrm.available() >= regions_to_expand) {
1707 // We had head room...
1708 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1709 }
1710 }
1711 return regions_to_expand > 0;
1712 }
1713
1714 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1715 size_t aligned_shrink_bytes =
1716 ReservedSpace::page_align_size_down(shrink_bytes);
1717 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1718 HeapRegion::GrainBytes);
1719 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1720
1721 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1722 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1723
1724
1725 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",
1726 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1727 if (num_regions_removed > 0) {
1728 g1_policy()->record_new_heap_size(num_regions());
1729 } else {
1730 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1731 }
1732 }
1733
1734 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1735 verify_region_sets_optional();
1736
1737 // We should only reach here at the end of a Full GC which means we
1738 // should not not be holding to any GC alloc regions. The method
1739 // below will make sure of that and do any remaining clean up.
1740 _allocator->abandon_gc_alloc_regions();
1741
1742 // Instead of tearing down / rebuilding the free lists here, we
1743 // could instead use the remove_all_pending() method on free_list to
1744 // remove only the ones that we need to remove.
1745 tear_down_region_sets(true /* free_list_only */);
1746 shrink_helper(shrink_bytes);
1747 rebuild_region_sets(true /* free_list_only */);
1748
1749 _hrm.verify_optional();
1750 verify_region_sets_optional();
1751 }
1752
1753 // Public methods.
1754
1755 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1756 CollectedHeap(),
1757 _g1_policy(policy_),
1758 _dirty_card_queue_set(false),
1759 _is_alive_closure_cm(this),
1760 _is_alive_closure_stw(this),
1761 _ref_processor_cm(NULL),
1762 _ref_processor_stw(NULL),
1763 _bot_shared(NULL),
1764 _cg1r(NULL),
1765 _g1mm(NULL),
1766 _refine_cte_cl(NULL),
1767 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1768 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1769 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1770 _humongous_reclaim_candidates(),
1771 _has_humongous_reclaim_candidates(false),
1772 _archive_allocator(NULL),
1773 _free_regions_coming(false),
1774 _young_list(new YoungList(this)),
1775 _gc_time_stamp(0),
1776 _summary_bytes_used(0),
1777 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1778 _old_evac_stats(OldPLABSize, PLABWeight),
1779 _expand_heap_after_alloc_failure(true),
1780 _old_marking_cycles_started(0),
1781 _old_marking_cycles_completed(0),
1782 _heap_summary_sent(false),
1783 _in_cset_fast_test(),
1784 _dirty_cards_region_list(NULL),
1785 _worker_cset_start_region(NULL),
1786 _worker_cset_start_region_time_stamp(NULL),
1787 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1788 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1789 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1790 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1791
1792 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1793 /* are_GC_task_threads */true,
1794 /* are_ConcurrentGC_threads */false);
1795 _workers->initialize_workers();
1796
1797 _allocator = G1Allocator::create_allocator(this);
1798 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1799
1800 // Override the default _filler_array_max_size so that no humongous filler
1801 // objects are created.
1802 _filler_array_max_size = _humongous_object_threshold_in_words;
1803
1804 uint n_queues = ParallelGCThreads;
1805 _task_queues = new RefToScanQueueSet(n_queues);
1806
1807 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1808 assert(n_rem_sets > 0, "Invariant.");
1809
1810 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1811 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1812 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1813
1814 for (uint i = 0; i < n_queues; i++) {
1815 RefToScanQueue* q = new RefToScanQueue();
1816 q->initialize();
1817 _task_queues->register_queue(i, q);
1818 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1819 }
1820 clear_cset_start_regions();
1821
1822 // Initialize the G1EvacuationFailureALot counters and flags.
1823 NOT_PRODUCT(reset_evacuation_should_fail();)
1824
1825 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1826 }
1827
1828 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1829 size_t size,
1830 size_t translation_factor) {
1831 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1832 // Allocate a new reserved space, preferring to use large pages.
1833 ReservedSpace rs(size, preferred_page_size);
1834 G1RegionToSpaceMapper* result =
1835 G1RegionToSpaceMapper::create_mapper(rs,
1836 size,
1837 rs.alignment(),
1838 HeapRegion::GrainBytes,
1839 translation_factor,
1840 mtGC);
1841 if (TracePageSizes) {
1842 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1843 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1844 }
1845 return result;
1846 }
1847
1848 jint G1CollectedHeap::initialize() {
1849 CollectedHeap::pre_initialize();
1850 os::enable_vtime();
1851
1852 // Necessary to satisfy locking discipline assertions.
1853
1854 MutexLocker x(Heap_lock);
1855
1856 // While there are no constraints in the GC code that HeapWordSize
1857 // be any particular value, there are multiple other areas in the
1858 // system which believe this to be true (e.g. oop->object_size in some
1859 // cases incorrectly returns the size in wordSize units rather than
1860 // HeapWordSize).
1861 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1862
1863 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1864 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1865 size_t heap_alignment = collector_policy()->heap_alignment();
1866
1867 // Ensure that the sizes are properly aligned.
1868 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1869 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1870 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1871
1872 _refine_cte_cl = new RefineCardTableEntryClosure();
1873
1874 jint ecode = JNI_OK;
1875 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1876 if (_cg1r == NULL) {
1877 return ecode;
1878 }
1879
1880 // Reserve the maximum.
1881
1882 // When compressed oops are enabled, the preferred heap base
1883 // is calculated by subtracting the requested size from the
1884 // 32Gb boundary and using the result as the base address for
1885 // heap reservation. If the requested size is not aligned to
1886 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1887 // into the ReservedHeapSpace constructor) then the actual
1888 // base of the reserved heap may end up differing from the
1889 // address that was requested (i.e. the preferred heap base).
1890 // If this happens then we could end up using a non-optimal
1891 // compressed oops mode.
1892
1893 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1894 heap_alignment);
1895
1896 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1897
1898 // Create the barrier set for the entire reserved region.
1899 G1SATBCardTableLoggingModRefBS* bs
1900 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1901 bs->initialize();
1902 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1903 set_barrier_set(bs);
1904
1905 // Also create a G1 rem set.
1906 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1907
1908 // Carve out the G1 part of the heap.
1909
1910 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1911 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1912 G1RegionToSpaceMapper* heap_storage =
1913 G1RegionToSpaceMapper::create_mapper(g1_rs,
1914 g1_rs.size(),
1915 page_size,
1916 HeapRegion::GrainBytes,
1917 1,
1918 mtJavaHeap);
1919 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1920 max_byte_size, page_size,
1921 heap_rs.base(),
1922 heap_rs.size());
1923 heap_storage->set_mapping_changed_listener(&_listener);
1924
1925 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1926 G1RegionToSpaceMapper* bot_storage =
1927 create_aux_memory_mapper("Block offset table",
1928 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1929 G1BlockOffsetSharedArray::heap_map_factor());
1930
1931 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1932 G1RegionToSpaceMapper* cardtable_storage =
1933 create_aux_memory_mapper("Card table",
1934 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1935 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1936
1937 G1RegionToSpaceMapper* card_counts_storage =
1938 create_aux_memory_mapper("Card counts table",
1939 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1940 G1CardCounts::heap_map_factor());
1941
1942 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1943 G1RegionToSpaceMapper* prev_bitmap_storage =
1944 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1945 G1RegionToSpaceMapper* next_bitmap_storage =
1946 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1947
1948 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1949 g1_barrier_set()->initialize(cardtable_storage);
1950 // Do later initialization work for concurrent refinement.
1951 _cg1r->init(card_counts_storage);
1952
1953 // 6843694 - ensure that the maximum region index can fit
1954 // in the remembered set structures.
1955 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1956 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1957
1958 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1959 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1960 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1961 "too many cards per region");
1962
1963 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1964
1965 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1966
1967 {
1968 HeapWord* start = _hrm.reserved().start();
1969 HeapWord* end = _hrm.reserved().end();
1970 size_t granularity = HeapRegion::GrainBytes;
1971
1972 _in_cset_fast_test.initialize(start, end, granularity);
1973 _humongous_reclaim_candidates.initialize(start, end, granularity);
1974 }
1975
1976 // Create the ConcurrentMark data structure and thread.
1977 // (Must do this late, so that "max_regions" is defined.)
1978 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1979 if (_cm == NULL || !_cm->completed_initialization()) {
1980 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1981 return JNI_ENOMEM;
1982 }
1983 _cmThread = _cm->cmThread();
1984
1985 // Initialize the from_card cache structure of HeapRegionRemSet.
1986 HeapRegionRemSet::init_heap(max_regions());
1987
1988 // Now expand into the initial heap size.
1989 if (!expand(init_byte_size)) {
1990 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1991 return JNI_ENOMEM;
1992 }
1993
1994 // Perform any initialization actions delegated to the policy.
1995 g1_policy()->init();
1996
1997 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1998 SATB_Q_FL_lock,
1999 G1SATBProcessCompletedThreshold,
2000 Shared_SATB_Q_lock);
2001
2002 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2003 DirtyCardQ_CBL_mon,
2004 DirtyCardQ_FL_lock,
2005 concurrent_g1_refine()->yellow_zone(),
2006 concurrent_g1_refine()->red_zone(),
2007 Shared_DirtyCardQ_lock);
2008
2009 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2010 DirtyCardQ_CBL_mon,
2011 DirtyCardQ_FL_lock,
2012 -1, // never trigger processing
2013 -1, // no limit on length
2014 Shared_DirtyCardQ_lock,
2015 &JavaThread::dirty_card_queue_set());
2016
2017 // Here we allocate the dummy HeapRegion that is required by the
2018 // G1AllocRegion class.
2019 HeapRegion* dummy_region = _hrm.get_dummy_region();
2020
2021 // We'll re-use the same region whether the alloc region will
2022 // require BOT updates or not and, if it doesn't, then a non-young
2023 // region will complain that it cannot support allocations without
2024 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2025 dummy_region->set_eden();
2026 // Make sure it's full.
2027 dummy_region->set_top(dummy_region->end());
2028 G1AllocRegion::setup(this, dummy_region);
2029
2030 _allocator->init_mutator_alloc_region();
2031
2032 // Do create of the monitoring and management support so that
2033 // values in the heap have been properly initialized.
2034 _g1mm = new G1MonitoringSupport(this);
2035
2036 G1StringDedup::initialize();
2037
2038 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2039 for (uint i = 0; i < ParallelGCThreads; i++) {
2040 new (&_preserved_objs[i]) OopAndMarkOopStack();
2041 }
2042
2043 return JNI_OK;
2044 }
2045
2046 void G1CollectedHeap::stop() {
2047 // Stop all concurrent threads. We do this to make sure these threads
2048 // do not continue to execute and access resources (e.g. logging)
2049 // that are destroyed during shutdown.
2050 _cg1r->stop();
2051 _cmThread->stop();
2052 if (G1StringDedup::is_enabled()) {
2053 G1StringDedup::stop();
2054 }
2055 }
2056
2057 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2058 return HeapRegion::max_region_size();
2059 }
2060
2061 void G1CollectedHeap::post_initialize() {
2062 CollectedHeap::post_initialize();
2063 ref_processing_init();
2064 }
2065
2066 void G1CollectedHeap::ref_processing_init() {
2067 // Reference processing in G1 currently works as follows:
2068 //
2069 // * There are two reference processor instances. One is
2070 // used to record and process discovered references
2071 // during concurrent marking; the other is used to
2072 // record and process references during STW pauses
2073 // (both full and incremental).
2074 // * Both ref processors need to 'span' the entire heap as
2075 // the regions in the collection set may be dotted around.
2076 //
2077 // * For the concurrent marking ref processor:
2078 // * Reference discovery is enabled at initial marking.
2079 // * Reference discovery is disabled and the discovered
2080 // references processed etc during remarking.
2081 // * Reference discovery is MT (see below).
2082 // * Reference discovery requires a barrier (see below).
2083 // * Reference processing may or may not be MT
2084 // (depending on the value of ParallelRefProcEnabled
2085 // and ParallelGCThreads).
2086 // * A full GC disables reference discovery by the CM
2087 // ref processor and abandons any entries on it's
2088 // discovered lists.
2089 //
2090 // * For the STW processor:
2091 // * Non MT discovery is enabled at the start of a full GC.
2092 // * Processing and enqueueing during a full GC is non-MT.
2093 // * During a full GC, references are processed after marking.
2094 //
2095 // * Discovery (may or may not be MT) is enabled at the start
2096 // of an incremental evacuation pause.
2097 // * References are processed near the end of a STW evacuation pause.
2098 // * For both types of GC:
2099 // * Discovery is atomic - i.e. not concurrent.
2100 // * Reference discovery will not need a barrier.
2101
2102 MemRegion mr = reserved_region();
2103
2104 // Concurrent Mark ref processor
2105 _ref_processor_cm =
2106 new ReferenceProcessor(mr, // span
2107 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2108 // mt processing
2109 ParallelGCThreads,
2110 // degree of mt processing
2111 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2112 // mt discovery
2113 MAX2(ParallelGCThreads, ConcGCThreads),
2114 // degree of mt discovery
2115 false,
2116 // Reference discovery is not atomic
2117 &_is_alive_closure_cm);
2118 // is alive closure
2119 // (for efficiency/performance)
2120
2121 // STW ref processor
2122 _ref_processor_stw =
2123 new ReferenceProcessor(mr, // span
2124 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2125 // mt processing
2126 ParallelGCThreads,
2127 // degree of mt processing
2128 (ParallelGCThreads > 1),
2129 // mt discovery
2130 ParallelGCThreads,
2131 // degree of mt discovery
2132 true,
2133 // Reference discovery is atomic
2134 &_is_alive_closure_stw);
2135 // is alive closure
2136 // (for efficiency/performance)
2137 }
2138
2139 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2140 return g1_policy();
2141 }
2142
2143 size_t G1CollectedHeap::capacity() const {
2144 return _hrm.length() * HeapRegion::GrainBytes;
2145 }
2146
2147 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2148 hr->reset_gc_time_stamp();
2149 }
2150
2151 #ifndef PRODUCT
2152
2153 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2154 private:
2155 unsigned _gc_time_stamp;
2156 bool _failures;
2157
2158 public:
2159 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2160 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2161
2162 virtual bool doHeapRegion(HeapRegion* hr) {
2163 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2164 if (_gc_time_stamp != region_gc_time_stamp) {
2165 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2166 region_gc_time_stamp, _gc_time_stamp);
2167 _failures = true;
2168 }
2169 return false;
2170 }
2171
2172 bool failures() { return _failures; }
2173 };
2174
2175 void G1CollectedHeap::check_gc_time_stamps() {
2176 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2177 heap_region_iterate(&cl);
2178 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2179 }
2180 #endif // PRODUCT
2181
2182 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2183 _cg1r->hot_card_cache()->drain(cl, worker_i);
2184 }
2185
2186 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2187 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2188 size_t n_completed_buffers = 0;
2189 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2190 n_completed_buffers++;
2191 }
2192 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2193 dcqs.clear_n_completed_buffers();
2194 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2195 }
2196
2197 // Computes the sum of the storage used by the various regions.
2198 size_t G1CollectedHeap::used() const {
2199 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2200 if (_archive_allocator != NULL) {
2201 result += _archive_allocator->used();
2202 }
2203 return result;
2204 }
2205
2206 size_t G1CollectedHeap::used_unlocked() const {
2207 return _summary_bytes_used;
2208 }
2209
2210 class SumUsedClosure: public HeapRegionClosure {
2211 size_t _used;
2212 public:
2213 SumUsedClosure() : _used(0) {}
2214 bool doHeapRegion(HeapRegion* r) {
2215 _used += r->used();
2216 return false;
2217 }
2218 size_t result() { return _used; }
2219 };
2220
2221 size_t G1CollectedHeap::recalculate_used() const {
2222 double recalculate_used_start = os::elapsedTime();
2223
2224 SumUsedClosure blk;
2225 heap_region_iterate(&blk);
2226
2227 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2228 return blk.result();
2229 }
2230
2231 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2232 switch (cause) {
2233 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2234 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2235 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2236 case GCCause::_g1_humongous_allocation: return true;
2237 case GCCause::_update_allocation_context_stats_inc: return true;
2238 case GCCause::_wb_conc_mark: return true;
2239 default: return false;
2240 }
2241 }
2242
2243 #ifndef PRODUCT
2244 void G1CollectedHeap::allocate_dummy_regions() {
2245 // Let's fill up most of the region
2246 size_t word_size = HeapRegion::GrainWords - 1024;
2247 // And as a result the region we'll allocate will be humongous.
2248 guarantee(is_humongous(word_size), "sanity");
2249
2250 // _filler_array_max_size is set to humongous object threshold
2251 // but temporarily change it to use CollectedHeap::fill_with_object().
2252 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2253
2254 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2255 // Let's use the existing mechanism for the allocation
2256 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2257 AllocationContext::system());
2258 if (dummy_obj != NULL) {
2259 MemRegion mr(dummy_obj, word_size);
2260 CollectedHeap::fill_with_object(mr);
2261 } else {
2262 // If we can't allocate once, we probably cannot allocate
2263 // again. Let's get out of the loop.
2264 break;
2265 }
2266 }
2267 }
2268 #endif // !PRODUCT
2269
2270 void G1CollectedHeap::increment_old_marking_cycles_started() {
2271 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2272 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2273 "Wrong marking cycle count (started: %d, completed: %d)",
2274 _old_marking_cycles_started, _old_marking_cycles_completed);
2275
2276 _old_marking_cycles_started++;
2277 }
2278
2279 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2280 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2281
2282 // We assume that if concurrent == true, then the caller is a
2283 // concurrent thread that was joined the Suspendible Thread
2284 // Set. If there's ever a cheap way to check this, we should add an
2285 // assert here.
2286
2287 // Given that this method is called at the end of a Full GC or of a
2288 // concurrent cycle, and those can be nested (i.e., a Full GC can
2289 // interrupt a concurrent cycle), the number of full collections
2290 // completed should be either one (in the case where there was no
2291 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2292 // behind the number of full collections started.
2293
2294 // This is the case for the inner caller, i.e. a Full GC.
2295 assert(concurrent ||
2296 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2297 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2298 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2299 "is inconsistent with _old_marking_cycles_completed = %u",
2300 _old_marking_cycles_started, _old_marking_cycles_completed);
2301
2302 // This is the case for the outer caller, i.e. the concurrent cycle.
2303 assert(!concurrent ||
2304 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2305 "for outer caller (concurrent cycle): "
2306 "_old_marking_cycles_started = %u "
2307 "is inconsistent with _old_marking_cycles_completed = %u",
2308 _old_marking_cycles_started, _old_marking_cycles_completed);
2309
2310 _old_marking_cycles_completed += 1;
2311
2312 // We need to clear the "in_progress" flag in the CM thread before
2313 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2314 // is set) so that if a waiter requests another System.gc() it doesn't
2315 // incorrectly see that a marking cycle is still in progress.
2316 if (concurrent) {
2317 _cmThread->set_idle();
2318 }
2319
2320 // This notify_all() will ensure that a thread that called
2321 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2322 // and it's waiting for a full GC to finish will be woken up. It is
2323 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2324 FullGCCount_lock->notify_all();
2325 }
2326
2327 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2328 GCIdMarkAndRestore conc_gc_id_mark;
2329 collector_state()->set_concurrent_cycle_started(true);
2330 _gc_timer_cm->register_gc_start(start_time);
2331
2332 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2333 trace_heap_before_gc(_gc_tracer_cm);
2334 _cmThread->set_gc_id(GCId::current());
2335 }
2336
2337 void G1CollectedHeap::register_concurrent_cycle_end() {
2338 if (collector_state()->concurrent_cycle_started()) {
2339 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2340 if (_cm->has_aborted()) {
2341 _gc_tracer_cm->report_concurrent_mode_failure();
2342 }
2343
2344 _gc_timer_cm->register_gc_end();
2345 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2346
2347 // Clear state variables to prepare for the next concurrent cycle.
2348 collector_state()->set_concurrent_cycle_started(false);
2349 _heap_summary_sent = false;
2350 }
2351 }
2352
2353 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2354 if (collector_state()->concurrent_cycle_started()) {
2355 // This function can be called when:
2356 // the cleanup pause is run
2357 // the concurrent cycle is aborted before the cleanup pause.
2358 // the concurrent cycle is aborted after the cleanup pause,
2359 // but before the concurrent cycle end has been registered.
2360 // Make sure that we only send the heap information once.
2361 if (!_heap_summary_sent) {
2362 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2363 trace_heap_after_gc(_gc_tracer_cm);
2364 _heap_summary_sent = true;
2365 }
2366 }
2367 }
2368
2369 void G1CollectedHeap::collect(GCCause::Cause cause) {
2370 assert_heap_not_locked();
2371
2372 uint gc_count_before;
2373 uint old_marking_count_before;
2374 uint full_gc_count_before;
2375 bool retry_gc;
2376
2377 do {
2378 retry_gc = false;
2379
2380 {
2381 MutexLocker ml(Heap_lock);
2382
2383 // Read the GC count while holding the Heap_lock
2384 gc_count_before = total_collections();
2385 full_gc_count_before = total_full_collections();
2386 old_marking_count_before = _old_marking_cycles_started;
2387 }
2388
2389 if (should_do_concurrent_full_gc(cause)) {
2390 // Schedule an initial-mark evacuation pause that will start a
2391 // concurrent cycle. We're setting word_size to 0 which means that
2392 // we are not requesting a post-GC allocation.
2393 VM_G1IncCollectionPause op(gc_count_before,
2394 0, /* word_size */
2395 true, /* should_initiate_conc_mark */
2396 g1_policy()->max_pause_time_ms(),
2397 cause);
2398 op.set_allocation_context(AllocationContext::current());
2399
2400 VMThread::execute(&op);
2401 if (!op.pause_succeeded()) {
2402 if (old_marking_count_before == _old_marking_cycles_started) {
2403 retry_gc = op.should_retry_gc();
2404 } else {
2405 // A Full GC happened while we were trying to schedule the
2406 // initial-mark GC. No point in starting a new cycle given
2407 // that the whole heap was collected anyway.
2408 }
2409
2410 if (retry_gc) {
2411 if (GC_locker::is_active_and_needs_gc()) {
2412 GC_locker::stall_until_clear();
2413 }
2414 }
2415 }
2416 } else {
2417 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2418 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2419
2420 // Schedule a standard evacuation pause. We're setting word_size
2421 // to 0 which means that we are not requesting a post-GC allocation.
2422 VM_G1IncCollectionPause op(gc_count_before,
2423 0, /* word_size */
2424 false, /* should_initiate_conc_mark */
2425 g1_policy()->max_pause_time_ms(),
2426 cause);
2427 VMThread::execute(&op);
2428 } else {
2429 // Schedule a Full GC.
2430 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2431 VMThread::execute(&op);
2432 }
2433 }
2434 } while (retry_gc);
2435 }
2436
2437 bool G1CollectedHeap::is_in(const void* p) const {
2438 if (_hrm.reserved().contains(p)) {
2439 // Given that we know that p is in the reserved space,
2440 // heap_region_containing() should successfully
2441 // return the containing region.
2442 HeapRegion* hr = heap_region_containing(p);
2443 return hr->is_in(p);
2444 } else {
2445 return false;
2446 }
2447 }
2448
2449 #ifdef ASSERT
2450 bool G1CollectedHeap::is_in_exact(const void* p) const {
2451 bool contains = reserved_region().contains(p);
2452 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2453 if (contains && available) {
2454 return true;
2455 } else {
2456 return false;
2457 }
2458 }
2459 #endif
2460
2461 bool G1CollectedHeap::obj_in_cs(oop obj) {
2462 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2463 return r != NULL && r->in_collection_set();
2464 }
2465
2466 // Iteration functions.
2467
2468 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2469
2470 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2471 ExtendedOopClosure* _cl;
2472 public:
2473 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2474 bool doHeapRegion(HeapRegion* r) {
2475 if (!r->is_continues_humongous()) {
2476 r->oop_iterate(_cl);
2477 }
2478 return false;
2479 }
2480 };
2481
2482 // Iterates an ObjectClosure over all objects within a HeapRegion.
2483
2484 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2485 ObjectClosure* _cl;
2486 public:
2487 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2488 bool doHeapRegion(HeapRegion* r) {
2489 if (!r->is_continues_humongous()) {
2490 r->object_iterate(_cl);
2491 }
2492 return false;
2493 }
2494 };
2495
2496 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2497 IterateObjectClosureRegionClosure blk(cl);
2498 heap_region_iterate(&blk);
2499 }
2500
2501 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2502 _hrm.iterate(cl);
2503 }
2504
2505 void
2506 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2507 uint worker_id,
2508 HeapRegionClaimer *hrclaimer,
2509 bool concurrent) const {
2510 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2511 }
2512
2513 // Clear the cached CSet starting regions and (more importantly)
2514 // the time stamps. Called when we reset the GC time stamp.
2515 void G1CollectedHeap::clear_cset_start_regions() {
2516 assert(_worker_cset_start_region != NULL, "sanity");
2517 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2518
2519 for (uint i = 0; i < ParallelGCThreads; i++) {
2520 _worker_cset_start_region[i] = NULL;
2521 _worker_cset_start_region_time_stamp[i] = 0;
2522 }
2523 }
2524
2525 // Given the id of a worker, obtain or calculate a suitable
2526 // starting region for iterating over the current collection set.
2527 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2528 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2529
2530 HeapRegion* result = NULL;
2531 unsigned gc_time_stamp = get_gc_time_stamp();
2532
2533 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2534 // Cached starting region for current worker was set
2535 // during the current pause - so it's valid.
2536 // Note: the cached starting heap region may be NULL
2537 // (when the collection set is empty).
2538 result = _worker_cset_start_region[worker_i];
2539 assert(result == NULL || result->in_collection_set(), "sanity");
2540 return result;
2541 }
2542
2543 // The cached entry was not valid so let's calculate
2544 // a suitable starting heap region for this worker.
2545
2546 // We want the parallel threads to start their collection
2547 // set iteration at different collection set regions to
2548 // avoid contention.
2549 // If we have:
2550 // n collection set regions
2551 // p threads
2552 // Then thread t will start at region floor ((t * n) / p)
2553
2554 result = g1_policy()->collection_set();
2555 uint cs_size = g1_policy()->cset_region_length();
2556 uint active_workers = workers()->active_workers();
2557
2558 uint end_ind = (cs_size * worker_i) / active_workers;
2559 uint start_ind = 0;
2560
2561 if (worker_i > 0 &&
2562 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2563 // Previous workers starting region is valid
2564 // so let's iterate from there
2565 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2566 result = _worker_cset_start_region[worker_i - 1];
2567 }
2568
2569 for (uint i = start_ind; i < end_ind; i++) {
2570 result = result->next_in_collection_set();
2571 }
2572
2573 // Note: the calculated starting heap region may be NULL
2574 // (when the collection set is empty).
2575 assert(result == NULL || result->in_collection_set(), "sanity");
2576 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2577 "should be updated only once per pause");
2578 _worker_cset_start_region[worker_i] = result;
2579 OrderAccess::storestore();
2580 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2581 return result;
2582 }
2583
2584 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2585 HeapRegion* r = g1_policy()->collection_set();
2586 while (r != NULL) {
2587 HeapRegion* next = r->next_in_collection_set();
2588 if (cl->doHeapRegion(r)) {
2589 cl->incomplete();
2590 return;
2591 }
2592 r = next;
2593 }
2594 }
2595
2596 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2597 HeapRegionClosure *cl) {
2598 if (r == NULL) {
2599 // The CSet is empty so there's nothing to do.
2600 return;
2601 }
2602
2603 assert(r->in_collection_set(),
2604 "Start region must be a member of the collection set.");
2605 HeapRegion* cur = r;
2606 while (cur != NULL) {
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 cur = g1_policy()->collection_set();
2615 while (cur != r) {
2616 HeapRegion* next = cur->next_in_collection_set();
2617 if (cl->doHeapRegion(cur) && false) {
2618 cl->incomplete();
2619 return;
2620 }
2621 cur = next;
2622 }
2623 }
2624
2625 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2626 HeapRegion* result = _hrm.next_region_in_heap(from);
2627 while (result != NULL && result->is_pinned()) {
2628 result = _hrm.next_region_in_heap(result);
2629 }
2630 return result;
2631 }
2632
2633 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2634 HeapRegion* hr = heap_region_containing(addr);
2635 return hr->block_start(addr);
2636 }
2637
2638 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2639 HeapRegion* hr = heap_region_containing(addr);
2640 return hr->block_size(addr);
2641 }
2642
2643 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2644 HeapRegion* hr = heap_region_containing(addr);
2645 return hr->block_is_obj(addr);
2646 }
2647
2648 bool G1CollectedHeap::supports_tlab_allocation() const {
2649 return true;
2650 }
2651
2652 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2653 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2654 }
2655
2656 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2657 return young_list()->eden_used_bytes();
2658 }
2659
2660 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2661 // must be equal to the humongous object limit.
2662 size_t G1CollectedHeap::max_tlab_size() const {
2663 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2664 }
2665
2666 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2667 AllocationContext_t context = AllocationContext::current();
2668 return _allocator->unsafe_max_tlab_alloc(context);
2669 }
2670
2671 size_t G1CollectedHeap::max_capacity() const {
2672 return _hrm.reserved().byte_size();
2673 }
2674
2675 jlong G1CollectedHeap::millis_since_last_gc() {
2676 // assert(false, "NYI");
2677 return 0;
2678 }
2679
2680 void G1CollectedHeap::prepare_for_verify() {
2681 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2682 ensure_parsability(false);
2683 }
2684 g1_rem_set()->prepare_for_verify();
2685 }
2686
2687 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2688 VerifyOption vo) {
2689 switch (vo) {
2690 case VerifyOption_G1UsePrevMarking:
2691 return hr->obj_allocated_since_prev_marking(obj);
2692 case VerifyOption_G1UseNextMarking:
2693 return hr->obj_allocated_since_next_marking(obj);
2694 case VerifyOption_G1UseMarkWord:
2695 return false;
2696 default:
2697 ShouldNotReachHere();
2698 }
2699 return false; // keep some compilers happy
2700 }
2701
2702 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2703 switch (vo) {
2704 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2705 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2706 case VerifyOption_G1UseMarkWord: return NULL;
2707 default: ShouldNotReachHere();
2708 }
2709 return NULL; // keep some compilers happy
2710 }
2711
2712 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2713 switch (vo) {
2714 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2715 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2716 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2717 default: ShouldNotReachHere();
2718 }
2719 return false; // keep some compilers happy
2720 }
2721
2722 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2723 switch (vo) {
2724 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2725 case VerifyOption_G1UseNextMarking: return "NTAMS";
2726 case VerifyOption_G1UseMarkWord: return "NONE";
2727 default: ShouldNotReachHere();
2728 }
2729 return NULL; // keep some compilers happy
2730 }
2731
2732 class VerifyRootsClosure: public OopClosure {
2733 private:
2734 G1CollectedHeap* _g1h;
2735 VerifyOption _vo;
2736 bool _failures;
2737 public:
2738 // _vo == UsePrevMarking -> use "prev" marking information,
2739 // _vo == UseNextMarking -> use "next" marking information,
2740 // _vo == UseMarkWord -> use mark word from object header.
2741 VerifyRootsClosure(VerifyOption vo) :
2742 _g1h(G1CollectedHeap::heap()),
2743 _vo(vo),
2744 _failures(false) { }
2745
2746 bool failures() { return _failures; }
2747
2748 template <class T> void do_oop_nv(T* p) {
2749 T heap_oop = oopDesc::load_heap_oop(p);
2750 if (!oopDesc::is_null(heap_oop)) {
2751 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2752 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2753 LogHandle(gc, verify) log;
2754 log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2755 if (_vo == VerifyOption_G1UseMarkWord) {
2756 log.info(" Mark word: " PTR_FORMAT, p2i(obj->mark()));
2757 }
2758 ResourceMark rm;
2759 obj->print_on(log.info_stream());
2760 _failures = true;
2761 }
2762 }
2763 }
2764
2765 void do_oop(oop* p) { do_oop_nv(p); }
2766 void do_oop(narrowOop* p) { do_oop_nv(p); }
2767 };
2768
2769 class G1VerifyCodeRootOopClosure: public OopClosure {
2770 G1CollectedHeap* _g1h;
2771 OopClosure* _root_cl;
2772 nmethod* _nm;
2773 VerifyOption _vo;
2774 bool _failures;
2775
2776 template <class T> void do_oop_work(T* p) {
2777 // First verify that this root is live
2778 _root_cl->do_oop(p);
2779
2780 if (!G1VerifyHeapRegionCodeRoots) {
2781 // We're not verifying the code roots attached to heap region.
2782 return;
2783 }
2784
2785 // Don't check the code roots during marking verification in a full GC
2786 if (_vo == VerifyOption_G1UseMarkWord) {
2787 return;
2788 }
2789
2790 // Now verify that the current nmethod (which contains p) is
2791 // in the code root list of the heap region containing the
2792 // object referenced by p.
2793
2794 T heap_oop = oopDesc::load_heap_oop(p);
2795 if (!oopDesc::is_null(heap_oop)) {
2796 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2797
2798 // Now fetch the region containing the object
2799 HeapRegion* hr = _g1h->heap_region_containing(obj);
2800 HeapRegionRemSet* hrrs = hr->rem_set();
2801 // Verify that the strong code root list for this region
2802 // contains the nmethod
2803 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2804 log_info(gc, verify)("Code root location " PTR_FORMAT " "
2805 "from nmethod " PTR_FORMAT " not in strong "
2806 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2807 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2808 _failures = true;
2809 }
2810 }
2811 }
2812
2813 public:
2814 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2815 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2816
2817 void do_oop(oop* p) { do_oop_work(p); }
2818 void do_oop(narrowOop* p) { do_oop_work(p); }
2819
2820 void set_nmethod(nmethod* nm) { _nm = nm; }
2821 bool failures() { return _failures; }
2822 };
2823
2824 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2825 G1VerifyCodeRootOopClosure* _oop_cl;
2826
2827 public:
2828 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2829 _oop_cl(oop_cl) {}
2830
2831 void do_code_blob(CodeBlob* cb) {
2832 nmethod* nm = cb->as_nmethod_or_null();
2833 if (nm != NULL) {
2834 _oop_cl->set_nmethod(nm);
2835 nm->oops_do(_oop_cl);
2836 }
2837 }
2838 };
2839
2840 class YoungRefCounterClosure : public OopClosure {
2841 G1CollectedHeap* _g1h;
2842 int _count;
2843 public:
2844 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2845 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2846 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2847
2848 int count() { return _count; }
2849 void reset_count() { _count = 0; };
2850 };
2851
2852 class VerifyKlassClosure: public KlassClosure {
2853 YoungRefCounterClosure _young_ref_counter_closure;
2854 OopClosure *_oop_closure;
2855 public:
2856 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2857 void do_klass(Klass* k) {
2858 k->oops_do(_oop_closure);
2859
2860 _young_ref_counter_closure.reset_count();
2861 k->oops_do(&_young_ref_counter_closure);
2862 if (_young_ref_counter_closure.count() > 0) {
2863 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2864 }
2865 }
2866 };
2867
2868 class VerifyLivenessOopClosure: public OopClosure {
2869 G1CollectedHeap* _g1h;
2870 VerifyOption _vo;
2871 public:
2872 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2873 _g1h(g1h), _vo(vo)
2874 { }
2875 void do_oop(narrowOop *p) { do_oop_work(p); }
2876 void do_oop( oop *p) { do_oop_work(p); }
2877
2878 template <class T> void do_oop_work(T *p) {
2879 oop obj = oopDesc::load_decode_heap_oop(p);
2880 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2881 "Dead object referenced by a not dead object");
2882 }
2883 };
2884
2885 class VerifyObjsInRegionClosure: public ObjectClosure {
2886 private:
2887 G1CollectedHeap* _g1h;
2888 size_t _live_bytes;
2889 HeapRegion *_hr;
2890 VerifyOption _vo;
2891 public:
2892 // _vo == UsePrevMarking -> use "prev" marking information,
2893 // _vo == UseNextMarking -> use "next" marking information,
2894 // _vo == UseMarkWord -> use mark word from object header.
2895 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2896 : _live_bytes(0), _hr(hr), _vo(vo) {
2897 _g1h = G1CollectedHeap::heap();
2898 }
2899 void do_object(oop o) {
2900 VerifyLivenessOopClosure isLive(_g1h, _vo);
2901 assert(o != NULL, "Huh?");
2902 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2903 // If the object is alive according to the mark word,
2904 // then verify that the marking information agrees.
2905 // Note we can't verify the contra-positive of the
2906 // above: if the object is dead (according to the mark
2907 // word), it may not be marked, or may have been marked
2908 // but has since became dead, or may have been allocated
2909 // since the last marking.
2910 if (_vo == VerifyOption_G1UseMarkWord) {
2911 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2912 }
2913
2914 o->oop_iterate_no_header(&isLive);
2915 if (!_hr->obj_allocated_since_prev_marking(o)) {
2916 size_t obj_size = o->size(); // Make sure we don't overflow
2917 _live_bytes += (obj_size * HeapWordSize);
2918 }
2919 }
2920 }
2921 size_t live_bytes() { return _live_bytes; }
2922 };
2923
2924 class VerifyArchiveOopClosure: public OopClosure {
2925 public:
2926 VerifyArchiveOopClosure(HeapRegion *hr) { }
2927 void do_oop(narrowOop *p) { do_oop_work(p); }
2928 void do_oop( oop *p) { do_oop_work(p); }
2929
2930 template <class T> void do_oop_work(T *p) {
2931 oop obj = oopDesc::load_decode_heap_oop(p);
2932 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2933 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2934 p2i(p), p2i(obj));
2935 }
2936 };
2937
2938 class VerifyArchiveRegionClosure: public ObjectClosure {
2939 public:
2940 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2941 // Verify that all object pointers are to archive regions.
2942 void do_object(oop o) {
2943 VerifyArchiveOopClosure checkOop(NULL);
2944 assert(o != NULL, "Should not be here for NULL oops");
2945 o->oop_iterate_no_header(&checkOop);
2946 }
2947 };
2948
2949 class VerifyRegionClosure: public HeapRegionClosure {
2950 private:
2951 bool _par;
2952 VerifyOption _vo;
2953 bool _failures;
2954 public:
2955 // _vo == UsePrevMarking -> use "prev" marking information,
2956 // _vo == UseNextMarking -> use "next" marking information,
2957 // _vo == UseMarkWord -> use mark word from object header.
2958 VerifyRegionClosure(bool par, VerifyOption vo)
2959 : _par(par),
2960 _vo(vo),
2961 _failures(false) {}
2962
2963 bool failures() {
2964 return _failures;
2965 }
2966
2967 bool doHeapRegion(HeapRegion* r) {
2968 // For archive regions, verify there are no heap pointers to
2969 // non-pinned regions. For all others, verify liveness info.
2970 if (r->is_archive()) {
2971 VerifyArchiveRegionClosure verify_oop_pointers(r);
2972 r->object_iterate(&verify_oop_pointers);
2973 return true;
2974 }
2975 if (!r->is_continues_humongous()) {
2976 bool failures = false;
2977 r->verify(_vo, &failures);
2978 if (failures) {
2979 _failures = true;
2980 } else if (!r->is_starts_humongous()) {
2981 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2982 r->object_iterate(¬_dead_yet_cl);
2983 if (_vo != VerifyOption_G1UseNextMarking) {
2984 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2985 log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2986 p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2987 _failures = true;
2988 }
2989 } else {
2990 // When vo == UseNextMarking we cannot currently do a sanity
2991 // check on the live bytes as the calculation has not been
2992 // finalized yet.
2993 }
2994 }
2995 }
2996 return false; // stop the region iteration if we hit a failure
2997 }
2998 };
2999
3000 // This is the task used for parallel verification of the heap regions
3001
3002 class G1ParVerifyTask: public AbstractGangTask {
3003 private:
3004 G1CollectedHeap* _g1h;
3005 VerifyOption _vo;
3006 bool _failures;
3007 HeapRegionClaimer _hrclaimer;
3008
3009 public:
3010 // _vo == UsePrevMarking -> use "prev" marking information,
3011 // _vo == UseNextMarking -> use "next" marking information,
3012 // _vo == UseMarkWord -> use mark word from object header.
3013 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3014 AbstractGangTask("Parallel verify task"),
3015 _g1h(g1h),
3016 _vo(vo),
3017 _failures(false),
3018 _hrclaimer(g1h->workers()->active_workers()) {}
3019
3020 bool failures() {
3021 return _failures;
3022 }
3023
3024 void work(uint worker_id) {
3025 HandleMark hm;
3026 VerifyRegionClosure blk(true, _vo);
3027 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3028 if (blk.failures()) {
3029 _failures = true;
3030 }
3031 }
3032 };
3033
3034 void G1CollectedHeap::verify(VerifyOption vo) {
3035 if (!SafepointSynchronize::is_at_safepoint()) {
3036 log_info(gc, verify)("Skipping verification. Not at safepoint.");
3037 }
3038
3039 assert(Thread::current()->is_VM_thread(),
3040 "Expected to be executed serially by the VM thread at this point");
3041
3042 log_debug(gc, verify)("Roots");
3043 VerifyRootsClosure rootsCl(vo);
3044 VerifyKlassClosure klassCl(this, &rootsCl);
3045 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3046
3047 // We apply the relevant closures to all the oops in the
3048 // system dictionary, class loader data graph, the string table
3049 // and the nmethods in the code cache.
3050 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3051 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3052
3053 {
3054 G1RootProcessor root_processor(this, 1);
3055 root_processor.process_all_roots(&rootsCl,
3056 &cldCl,
3057 &blobsCl);
3058 }
3059
3060 bool failures = rootsCl.failures() || codeRootsCl.failures();
3061
3062 if (vo != VerifyOption_G1UseMarkWord) {
3063 // If we're verifying during a full GC then the region sets
3064 // will have been torn down at the start of the GC. Therefore
3065 // verifying the region sets will fail. So we only verify
3066 // the region sets when not in a full GC.
3067 log_debug(gc, verify)("HeapRegionSets");
3068 verify_region_sets();
3069 }
3070
3071 log_debug(gc, verify)("HeapRegions");
3072 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3073
3074 G1ParVerifyTask task(this, vo);
3075 workers()->run_task(&task);
3076 if (task.failures()) {
3077 failures = true;
3078 }
3079
3080 } else {
3081 VerifyRegionClosure blk(false, vo);
3082 heap_region_iterate(&blk);
3083 if (blk.failures()) {
3084 failures = true;
3085 }
3086 }
3087
3088 if (G1StringDedup::is_enabled()) {
3089 log_debug(gc, verify)("StrDedup");
3090 G1StringDedup::verify();
3091 }
3092
3093 if (failures) {
3094 log_info(gc, verify)("Heap after failed verification:");
3095 // It helps to have the per-region information in the output to
3096 // help us track down what went wrong. This is why we call
3097 // print_extended_on() instead of print_on().
3098 LogHandle(gc, verify) log;
3099 ResourceMark rm;
3100 print_extended_on(log.info_stream());
3101 }
3102 guarantee(!failures, "there should not have been any failures");
3103 }
3104
3105 double G1CollectedHeap::verify(bool guard, const char* msg) {
3106 double verify_time_ms = 0.0;
3107
3108 if (guard && total_collections() >= VerifyGCStartAt) {
3109 double verify_start = os::elapsedTime();
3110 HandleMark hm; // Discard invalid handles created during verification
3111 prepare_for_verify();
3112 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3113 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3114 }
3115
3116 return verify_time_ms;
3117 }
3118
3119 void G1CollectedHeap::verify_before_gc() {
3120 double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3121 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3122 }
3123
3124 void G1CollectedHeap::verify_after_gc() {
3125 double verify_time_ms = verify(VerifyAfterGC, "After GC");
3126 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3127 }
3128
3129 class PrintRegionClosure: public HeapRegionClosure {
3130 outputStream* _st;
3131 public:
3132 PrintRegionClosure(outputStream* st) : _st(st) {}
3133 bool doHeapRegion(HeapRegion* r) {
3134 r->print_on(_st);
3135 return false;
3136 }
3137 };
3138
3139 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3140 const HeapRegion* hr,
3141 const VerifyOption vo) const {
3142 switch (vo) {
3143 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3144 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3145 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3146 default: ShouldNotReachHere();
3147 }
3148 return false; // keep some compilers happy
3149 }
3150
3151 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3152 const VerifyOption vo) const {
3153 switch (vo) {
3154 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3155 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3156 case VerifyOption_G1UseMarkWord: {
3157 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3158 return !obj->is_gc_marked() && !hr->is_archive();
3159 }
3160 default: ShouldNotReachHere();
3161 }
3162 return false; // keep some compilers happy
3163 }
3164
3165 void G1CollectedHeap::print_on(outputStream* st) const {
3166 st->print(" %-20s", "garbage-first heap");
3167 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3168 capacity()/K, used_unlocked()/K);
3169 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3170 p2i(_hrm.reserved().start()),
3171 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3172 p2i(_hrm.reserved().end()));
3173 st->cr();
3174 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3175 uint young_regions = _young_list->length();
3176 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3177 (size_t) young_regions * HeapRegion::GrainBytes / K);
3178 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3179 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3180 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3181 st->cr();
3182 MetaspaceAux::print_on(st);
3183 }
3184
3185 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3186 print_on(st);
3187
3188 // Print the per-region information.
3189 st->cr();
3190 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3191 "HS=humongous(starts), HC=humongous(continues), "
3192 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3193 "PTAMS=previous top-at-mark-start, "
3194 "NTAMS=next top-at-mark-start)");
3195 PrintRegionClosure blk(st);
3196 heap_region_iterate(&blk);
3197 }
3198
3199 void G1CollectedHeap::print_on_error(outputStream* st) const {
3200 this->CollectedHeap::print_on_error(st);
3201
3202 if (_cm != NULL) {
3203 st->cr();
3204 _cm->print_on_error(st);
3205 }
3206 }
3207
3208 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3209 workers()->print_worker_threads_on(st);
3210 _cmThread->print_on(st);
3211 st->cr();
3212 _cm->print_worker_threads_on(st);
3213 _cg1r->print_worker_threads_on(st);
3214 if (G1StringDedup::is_enabled()) {
3215 G1StringDedup::print_worker_threads_on(st);
3216 }
3217 }
3218
3219 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3220 workers()->threads_do(tc);
3221 tc->do_thread(_cmThread);
3222 _cg1r->threads_do(tc);
3223 if (G1StringDedup::is_enabled()) {
3224 G1StringDedup::threads_do(tc);
3225 }
3226 }
3227
3228 void G1CollectedHeap::print_tracing_info() const {
3229 // We'll overload this to mean "trace GC pause statistics."
3230 if (TraceYoungGenTime || TraceOldGenTime) {
3231 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3232 // to that.
3233 g1_policy()->print_tracing_info();
3234 }
3235 g1_rem_set()->print_summary_info();
3236 concurrent_mark()->print_summary_info();
3237 g1_policy()->print_yg_surv_rate_info();
3238 }
3239
3240 #ifndef PRODUCT
3241 // Helpful for debugging RSet issues.
3242
3243 class PrintRSetsClosure : public HeapRegionClosure {
3244 private:
3245 const char* _msg;
3246 size_t _occupied_sum;
3247
3248 public:
3249 bool doHeapRegion(HeapRegion* r) {
3250 HeapRegionRemSet* hrrs = r->rem_set();
3251 size_t occupied = hrrs->occupied();
3252 _occupied_sum += occupied;
3253
3254 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
3255 if (occupied == 0) {
3256 tty->print_cr(" RSet is empty");
3257 } else {
3258 hrrs->print();
3259 }
3260 tty->print_cr("----------");
3261 return false;
3262 }
3263
3264 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3265 tty->cr();
3266 tty->print_cr("========================================");
3267 tty->print_cr("%s", msg);
3268 tty->cr();
3269 }
3270
3271 ~PrintRSetsClosure() {
3272 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3273 tty->print_cr("========================================");
3274 tty->cr();
3275 }
3276 };
3277
3278 void G1CollectedHeap::print_cset_rsets() {
3279 PrintRSetsClosure cl("Printing CSet RSets");
3280 collection_set_iterate(&cl);
3281 }
3282
3283 void G1CollectedHeap::print_all_rsets() {
3284 PrintRSetsClosure cl("Printing All RSets");;
3285 heap_region_iterate(&cl);
3286 }
3287 #endif // PRODUCT
3288
3289 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3290 YoungList* young_list = heap()->young_list();
3291
3292 size_t eden_used_bytes = young_list->eden_used_bytes();
3293 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3294
3295 size_t eden_capacity_bytes =
3296 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3297
3298 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3299 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3300 }
3301
3302 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3303 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3304 stats->unused(), stats->used(), stats->region_end_waste(),
3305 stats->regions_filled(), stats->direct_allocated(),
3306 stats->failure_used(), stats->failure_waste());
3307 }
3308
3309 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3310 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3311 gc_tracer->report_gc_heap_summary(when, heap_summary);
3312
3313 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3314 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3315 }
3316
3317
3318 G1CollectedHeap* G1CollectedHeap::heap() {
3319 CollectedHeap* heap = Universe::heap();
3320 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3321 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3322 return (G1CollectedHeap*)heap;
3323 }
3324
3325 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3326 // always_do_update_barrier = false;
3327 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3328 // Fill TLAB's and such
3329 accumulate_statistics_all_tlabs();
3330 ensure_parsability(true);
3331
3332 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3333 }
3334
3335 void G1CollectedHeap::gc_epilogue(bool full) {
3336 // we are at the end of the GC. Total collections has already been increased.
3337 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3338
3339 // FIXME: what is this about?
3340 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3341 // is set.
3342 #if defined(COMPILER2) || INCLUDE_JVMCI
3343 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3344 #endif
3345 // always_do_update_barrier = true;
3346
3347 resize_all_tlabs();
3348 allocation_context_stats().update(full);
3349
3350 // We have just completed a GC. Update the soft reference
3351 // policy with the new heap occupancy
3352 Universe::update_heap_info_at_gc();
3353 }
3354
3355 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3356 uint gc_count_before,
3357 bool* succeeded,
3358 GCCause::Cause gc_cause) {
3359 assert_heap_not_locked_and_not_at_safepoint();
3360 g1_policy()->record_stop_world_start();
3361 VM_G1IncCollectionPause op(gc_count_before,
3362 word_size,
3363 false, /* should_initiate_conc_mark */
3364 g1_policy()->max_pause_time_ms(),
3365 gc_cause);
3366
3367 op.set_allocation_context(AllocationContext::current());
3368 VMThread::execute(&op);
3369
3370 HeapWord* result = op.result();
3371 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3372 assert(result == NULL || ret_succeeded,
3373 "the result should be NULL if the VM did not succeed");
3374 *succeeded = ret_succeeded;
3375
3376 assert_heap_not_locked();
3377 return result;
3378 }
3379
3380 void
3381 G1CollectedHeap::doConcurrentMark() {
3382 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3383 if (!_cmThread->in_progress()) {
3384 _cmThread->set_started();
3385 CGC_lock->notify();
3386 }
3387 }
3388
3389 size_t G1CollectedHeap::pending_card_num() {
3390 size_t extra_cards = 0;
3391 JavaThread *curr = Threads::first();
3392 while (curr != NULL) {
3393 DirtyCardQueue& dcq = curr->dirty_card_queue();
3394 extra_cards += dcq.size();
3395 curr = curr->next();
3396 }
3397 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3398 size_t buffer_size = dcqs.buffer_size();
3399 size_t buffer_num = dcqs.completed_buffers_num();
3400
3401 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3402 // in bytes - not the number of 'entries'. We need to convert
3403 // into a number of cards.
3404 return (buffer_size * buffer_num + extra_cards) / oopSize;
3405 }
3406
3407 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3408 private:
3409 size_t _total_humongous;
3410 size_t _candidate_humongous;
3411
3412 DirtyCardQueue _dcq;
3413
3414 // We don't nominate objects with many remembered set entries, on
3415 // the assumption that such objects are likely still live.
3416 bool is_remset_small(HeapRegion* region) const {
3417 HeapRegionRemSet* const rset = region->rem_set();
3418 return G1EagerReclaimHumongousObjectsWithStaleRefs
3419 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3420 : rset->is_empty();
3421 }
3422
3423 bool is_typeArray_region(HeapRegion* region) const {
3424 return oop(region->bottom())->is_typeArray();
3425 }
3426
3427 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3428 assert(region->is_starts_humongous(), "Must start a humongous object");
3429
3430 // Candidate selection must satisfy the following constraints
3431 // while concurrent marking is in progress:
3432 //
3433 // * In order to maintain SATB invariants, an object must not be
3434 // reclaimed if it was allocated before the start of marking and
3435 // has not had its references scanned. Such an object must have
3436 // its references (including type metadata) scanned to ensure no
3437 // live objects are missed by the marking process. Objects
3438 // allocated after the start of concurrent marking don't need to
3439 // be scanned.
3440 //
3441 // * An object must not be reclaimed if it is on the concurrent
3442 // mark stack. Objects allocated after the start of concurrent
3443 // marking are never pushed on the mark stack.
3444 //
3445 // Nominating only objects allocated after the start of concurrent
3446 // marking is sufficient to meet both constraints. This may miss
3447 // some objects that satisfy the constraints, but the marking data
3448 // structures don't support efficiently performing the needed
3449 // additional tests or scrubbing of the mark stack.
3450 //
3451 // However, we presently only nominate is_typeArray() objects.
3452 // A humongous object containing references induces remembered
3453 // set entries on other regions. In order to reclaim such an
3454 // object, those remembered sets would need to be cleaned up.
3455 //
3456 // We also treat is_typeArray() objects specially, allowing them
3457 // to be reclaimed even if allocated before the start of
3458 // concurrent mark. For this we rely on mark stack insertion to
3459 // exclude is_typeArray() objects, preventing reclaiming an object
3460 // that is in the mark stack. We also rely on the metadata for
3461 // such objects to be built-in and so ensured to be kept live.
3462 // Frequent allocation and drop of large binary blobs is an
3463 // important use case for eager reclaim, and this special handling
3464 // may reduce needed headroom.
3465
3466 return is_typeArray_region(region) && is_remset_small(region);
3467 }
3468
3469 public:
3470 RegisterHumongousWithInCSetFastTestClosure()
3471 : _total_humongous(0),
3472 _candidate_humongous(0),
3473 _dcq(&JavaThread::dirty_card_queue_set()) {
3474 }
3475
3476 virtual bool doHeapRegion(HeapRegion* r) {
3477 if (!r->is_starts_humongous()) {
3478 return false;
3479 }
3480 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3481
3482 bool is_candidate = humongous_region_is_candidate(g1h, r);
3483 uint rindex = r->hrm_index();
3484 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3485 if (is_candidate) {
3486 _candidate_humongous++;
3487 g1h->register_humongous_region_with_cset(rindex);
3488 // Is_candidate already filters out humongous object with large remembered sets.
3489 // If we have a humongous object with a few remembered sets, we simply flush these
3490 // remembered set entries into the DCQS. That will result in automatic
3491 // re-evaluation of their remembered set entries during the following evacuation
3492 // phase.
3493 if (!r->rem_set()->is_empty()) {
3494 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3495 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3496 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3497 HeapRegionRemSetIterator hrrs(r->rem_set());
3498 size_t card_index;
3499 while (hrrs.has_next(card_index)) {
3500 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3501 // The remembered set might contain references to already freed
3502 // regions. Filter out such entries to avoid failing card table
3503 // verification.
3504 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3505 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3506 *card_ptr = CardTableModRefBS::dirty_card_val();
3507 _dcq.enqueue(card_ptr);
3508 }
3509 }
3510 }
3511 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3512 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3513 hrrs.n_yielded(), r->rem_set()->occupied());
3514 r->rem_set()->clear_locked();
3515 }
3516 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3517 }
3518 _total_humongous++;
3519
3520 return false;
3521 }
3522
3523 size_t total_humongous() const { return _total_humongous; }
3524 size_t candidate_humongous() const { return _candidate_humongous; }
3525
3526 void flush_rem_set_entries() { _dcq.flush(); }
3527 };
3528
3529 void G1CollectedHeap::register_humongous_regions_with_cset() {
3530 if (!G1EagerReclaimHumongousObjects) {
3531 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3532 return;
3533 }
3534 double time = os::elapsed_counter();
3535
3536 // Collect reclaim candidate information and register candidates with cset.
3537 RegisterHumongousWithInCSetFastTestClosure cl;
3538 heap_region_iterate(&cl);
3539
3540 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3541 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3542 cl.total_humongous(),
3543 cl.candidate_humongous());
3544 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3545
3546 // Finally flush all remembered set entries to re-check into the global DCQS.
3547 cl.flush_rem_set_entries();
3548 }
3549
3550 #ifdef ASSERT
3551 class VerifyCSetClosure: public HeapRegionClosure {
3552 public:
3553 bool doHeapRegion(HeapRegion* hr) {
3554 // Here we check that the CSet region's RSet is ready for parallel
3555 // iteration. The fields that we'll verify are only manipulated
3556 // when the region is part of a CSet and is collected. Afterwards,
3557 // we reset these fields when we clear the region's RSet (when the
3558 // region is freed) so they are ready when the region is
3559 // re-allocated. The only exception to this is if there's an
3560 // evacuation failure and instead of freeing the region we leave
3561 // it in the heap. In that case, we reset these fields during
3562 // evacuation failure handling.
3563 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3564
3565 // Here's a good place to add any other checks we'd like to
3566 // perform on CSet regions.
3567 return false;
3568 }
3569 };
3570 #endif // ASSERT
3571
3572 uint G1CollectedHeap::num_task_queues() const {
3573 return _task_queues->size();
3574 }
3575
3576 #if TASKQUEUE_STATS
3577 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3578 st->print_raw_cr("GC Task Stats");
3579 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3580 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3581 }
3582
3583 void G1CollectedHeap::print_taskqueue_stats() const {
3584 if (!develop_log_is_enabled(Trace, gc, task, stats)) {
3585 return;
3586 }
3587 LogHandle(gc, task, stats) log;
3588 ResourceMark rm;
3589 outputStream* st = log.trace_stream();
3590
3591 print_taskqueue_stats_hdr(st);
3592
3593 TaskQueueStats totals;
3594 const uint n = num_task_queues();
3595 for (uint i = 0; i < n; ++i) {
3596 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3597 totals += task_queue(i)->stats;
3598 }
3599 st->print_raw("tot "); totals.print(st); st->cr();
3600
3601 DEBUG_ONLY(totals.verify());
3602 }
3603
3604 void G1CollectedHeap::reset_taskqueue_stats() {
3605 const uint n = num_task_queues();
3606 for (uint i = 0; i < n; ++i) {
3607 task_queue(i)->stats.reset();
3608 }
3609 }
3610 #endif // TASKQUEUE_STATS
3611
3612 void G1CollectedHeap::log_gc_footer(double pause_time_counter) {
3613 if (evacuation_failed()) {
3614 log_info(gc)("To-space exhausted");
3615 }
3616
3617 double pause_time_sec = TimeHelper::counter_to_seconds(pause_time_counter);
3618 g1_policy()->print_phases(pause_time_sec);
3619
3620 g1_policy()->print_detailed_heap_transition();
3621 }
3622
3623
3624 void G1CollectedHeap::wait_for_root_region_scanning() {
3625 double scan_wait_start = os::elapsedTime();
3626 // We have to wait until the CM threads finish scanning the
3627 // root regions as it's the only way to ensure that all the
3628 // objects on them have been correctly scanned before we start
3629 // moving them during the GC.
3630 bool waited = _cm->root_regions()->wait_until_scan_finished();
3631 double wait_time_ms = 0.0;
3632 if (waited) {
3633 double scan_wait_end = os::elapsedTime();
3634 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3635 }
3636 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3637 }
3638
3639 bool
3640 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3641 assert_at_safepoint(true /* should_be_vm_thread */);
3642 guarantee(!is_gc_active(), "collection is not reentrant");
3643
3644 if (GC_locker::check_active_before_gc()) {
3645 return false;
3646 }
3647
3648 _gc_timer_stw->register_gc_start();
3649
3650 GCIdMark gc_id_mark;
3651 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3652
3653 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3654 ResourceMark rm;
3655
3656 wait_for_root_region_scanning();
3657
3658 print_heap_before_gc();
3659 trace_heap_before_gc(_gc_tracer_stw);
3660
3661 verify_region_sets_optional();
3662 verify_dirty_young_regions();
3663
3664 // This call will decide whether this pause is an initial-mark
3665 // pause. If it is, during_initial_mark_pause() will return true
3666 // for the duration of this pause.
3667 g1_policy()->decide_on_conc_mark_initiation();
3668
3669 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3670 assert(!collector_state()->during_initial_mark_pause() ||
3671 collector_state()->gcs_are_young(), "sanity");
3672
3673 // We also do not allow mixed GCs during marking.
3674 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3675
3676 // Record whether this pause is an initial mark. When the current
3677 // thread has completed its logging output and it's safe to signal
3678 // the CM thread, the flag's value in the policy has been reset.
3679 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3680
3681 // Inner scope for scope based logging, timers, and stats collection
3682 {
3683 EvacuationInfo evacuation_info;
3684
3685 if (collector_state()->during_initial_mark_pause()) {
3686 // We are about to start a marking cycle, so we increment the
3687 // full collection counter.
3688 increment_old_marking_cycles_started();
3689 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3690 }
3691
3692 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3693
3694 GCTraceCPUTime tcpu;
3695
3696 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3697 workers()->active_workers(),
3698 Threads::number_of_non_daemon_threads());
3699 workers()->set_active_workers(active_workers);
3700 FormatBuffer<> gc_string("Pause ");
3701 if (collector_state()->during_initial_mark_pause()) {
3702 gc_string.append("Initial Mark");
3703 } else if (collector_state()->gcs_are_young()) {
3704 gc_string.append("Young");
3705 } else {
3706 gc_string.append("Mixed");
3707 }
3708 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3709
3710 double pause_start_sec = os::elapsedTime();
3711 double pause_start_counter = os::elapsed_counter();
3712 g1_policy()->note_gc_start(active_workers);
3713
3714 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3715 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3716
3717 // If the secondary_free_list is not empty, append it to the
3718 // free_list. No need to wait for the cleanup operation to finish;
3719 // the region allocation code will check the secondary_free_list
3720 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3721 // set, skip this step so that the region allocation code has to
3722 // get entries from the secondary_free_list.
3723 if (!G1StressConcRegionFreeing) {
3724 append_secondary_free_list_if_not_empty_with_lock();
3725 }
3726
3727 assert(check_young_list_well_formed(), "young list should be well formed");
3728
3729 // Don't dynamically change the number of GC threads this early. A value of
3730 // 0 is used to indicate serial work. When parallel work is done,
3731 // it will be set.
3732
3733 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3734 IsGCActiveMark x;
3735
3736 gc_prologue(false);
3737 increment_total_collections(false /* full gc */);
3738 increment_gc_time_stamp();
3739
3740 verify_before_gc();
3741
3742 check_bitmaps("GC Start");
3743
3744 #if defined(COMPILER2) || INCLUDE_JVMCI
3745 DerivedPointerTable::clear();
3746 #endif
3747
3748 // Please see comment in g1CollectedHeap.hpp and
3749 // G1CollectedHeap::ref_processing_init() to see how
3750 // reference processing currently works in G1.
3751
3752 // Enable discovery in the STW reference processor
3753 if (g1_policy()->should_process_references()) {
3754 ref_processor_stw()->enable_discovery();
3755 } else {
3756 ref_processor_stw()->disable_discovery();
3757 }
3758
3759 {
3760 // We want to temporarily turn off discovery by the
3761 // CM ref processor, if necessary, and turn it back on
3762 // on again later if we do. Using a scoped
3763 // NoRefDiscovery object will do this.
3764 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3765
3766 // Forget the current alloc region (we might even choose it to be part
3767 // of the collection set!).
3768 _allocator->release_mutator_alloc_region();
3769
3770 // This timing is only used by the ergonomics to handle our pause target.
3771 // It is unclear why this should not include the full pause. We will
3772 // investigate this in CR 7178365.
3773 //
3774 // Preserving the old comment here if that helps the investigation:
3775 //
3776 // The elapsed time induced by the start time below deliberately elides
3777 // the possible verification above.
3778 double sample_start_time_sec = os::elapsedTime();
3779
3780 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3781
3782 if (collector_state()->during_initial_mark_pause()) {
3783 concurrent_mark()->checkpointRootsInitialPre();
3784 }
3785
3786 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3787 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3788
3789 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3790
3791 // Make sure the remembered sets are up to date. This needs to be
3792 // done before register_humongous_regions_with_cset(), because the
3793 // remembered sets are used there to choose eager reclaim candidates.
3794 // If the remembered sets are not up to date we might miss some
3795 // entries that need to be handled.
3796 g1_rem_set()->cleanupHRRS();
3797
3798 register_humongous_regions_with_cset();
3799
3800 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3801
3802 _cm->note_start_of_gc();
3803 // We call this after finalize_cset() to
3804 // ensure that the CSet has been finalized.
3805 _cm->verify_no_cset_oops();
3806
3807 if (_hr_printer.is_active()) {
3808 HeapRegion* hr = g1_policy()->collection_set();
3809 while (hr != NULL) {
3810 _hr_printer.cset(hr);
3811 hr = hr->next_in_collection_set();
3812 }
3813 }
3814
3815 #ifdef ASSERT
3816 VerifyCSetClosure cl;
3817 collection_set_iterate(&cl);
3818 #endif // ASSERT
3819
3820 // Initialize the GC alloc regions.
3821 _allocator->init_gc_alloc_regions(evacuation_info);
3822
3823 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3824 pre_evacuate_collection_set();
3825
3826 // Actually do the work...
3827 evacuate_collection_set(evacuation_info, &per_thread_states);
3828
3829 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3830
3831 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3832 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3833
3834 eagerly_reclaim_humongous_regions();
3835
3836 g1_policy()->clear_collection_set();
3837
3838 // Start a new incremental collection set for the next pause.
3839 g1_policy()->start_incremental_cset_building();
3840
3841 clear_cset_fast_test();
3842
3843 _young_list->reset_sampled_info();
3844
3845 // Don't check the whole heap at this point as the
3846 // GC alloc regions from this pause have been tagged
3847 // as survivors and moved on to the survivor list.
3848 // Survivor regions will fail the !is_young() check.
3849 assert(check_young_list_empty(false /* check_heap */),
3850 "young list should be empty");
3851
3852 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3853 _young_list->first_survivor_region(),
3854 _young_list->last_survivor_region());
3855
3856 _young_list->reset_auxilary_lists();
3857
3858 if (evacuation_failed()) {
3859 set_used(recalculate_used());
3860 if (_archive_allocator != NULL) {
3861 _archive_allocator->clear_used();
3862 }
3863 for (uint i = 0; i < ParallelGCThreads; i++) {
3864 if (_evacuation_failed_info_array[i].has_failed()) {
3865 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3866 }
3867 }
3868 } else {
3869 // The "used" of the the collection set have already been subtracted
3870 // when they were freed. Add in the bytes evacuated.
3871 increase_used(g1_policy()->bytes_copied_during_gc());
3872 }
3873
3874 if (collector_state()->during_initial_mark_pause()) {
3875 // We have to do this before we notify the CM threads that
3876 // they can start working to make sure that all the
3877 // appropriate initialization is done on the CM object.
3878 concurrent_mark()->checkpointRootsInitialPost();
3879 collector_state()->set_mark_in_progress(true);
3880 // Note that we don't actually trigger the CM thread at
3881 // this point. We do that later when we're sure that
3882 // the current thread has completed its logging output.
3883 }
3884
3885 allocate_dummy_regions();
3886
3887 _allocator->init_mutator_alloc_region();
3888
3889 {
3890 size_t expand_bytes = g1_policy()->expansion_amount();
3891 if (expand_bytes > 0) {
3892 size_t bytes_before = capacity();
3893 // No need for an ergo logging here,
3894 // expansion_amount() does this when it returns a value > 0.
3895 double expand_ms;
3896 if (!expand(expand_bytes, &expand_ms)) {
3897 // We failed to expand the heap. Cannot do anything about it.
3898 }
3899 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3900 }
3901 }
3902
3903 // We redo the verification but now wrt to the new CSet which
3904 // has just got initialized after the previous CSet was freed.
3905 _cm->verify_no_cset_oops();
3906 _cm->note_end_of_gc();
3907
3908 // This timing is only used by the ergonomics to handle our pause target.
3909 // It is unclear why this should not include the full pause. We will
3910 // investigate this in CR 7178365.
3911 double sample_end_time_sec = os::elapsedTime();
3912 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3913 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3914 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3915
3916 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3917 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3918
3919 MemoryService::track_memory_usage();
3920
3921 // In prepare_for_verify() below we'll need to scan the deferred
3922 // update buffers to bring the RSets up-to-date if
3923 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3924 // the update buffers we'll probably need to scan cards on the
3925 // regions we just allocated to (i.e., the GC alloc
3926 // regions). However, during the last GC we called
3927 // set_saved_mark() on all the GC alloc regions, so card
3928 // scanning might skip the [saved_mark_word()...top()] area of
3929 // those regions (i.e., the area we allocated objects into
3930 // during the last GC). But it shouldn't. Given that
3931 // saved_mark_word() is conditional on whether the GC time stamp
3932 // on the region is current or not, by incrementing the GC time
3933 // stamp here we invalidate all the GC time stamps on all the
3934 // regions and saved_mark_word() will simply return top() for
3935 // all the regions. This is a nicer way of ensuring this rather
3936 // than iterating over the regions and fixing them. In fact, the
3937 // GC time stamp increment here also ensures that
3938 // saved_mark_word() will return top() between pauses, i.e.,
3939 // during concurrent refinement. So we don't need the
3940 // is_gc_active() check to decided which top to use when
3941 // scanning cards (see CR 7039627).
3942 increment_gc_time_stamp();
3943
3944 verify_after_gc();
3945 check_bitmaps("GC End");
3946
3947 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3948 ref_processor_stw()->verify_no_references_recorded();
3949
3950 // CM reference discovery will be re-enabled if necessary.
3951 }
3952
3953 #ifdef TRACESPINNING
3954 ParallelTaskTerminator::print_termination_counts();
3955 #endif
3956
3957 gc_epilogue(false);
3958 }
3959
3960 // Print the remainder of the GC log output.
3961 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3962
3963 // It is not yet to safe to tell the concurrent mark to
3964 // start as we have some optional output below. We don't want the
3965 // output from the concurrent mark thread interfering with this
3966 // logging output either.
3967
3968 _hrm.verify_optional();
3969 verify_region_sets_optional();
3970
3971 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3972 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3973
3974 print_heap_after_gc();
3975 trace_heap_after_gc(_gc_tracer_stw);
3976
3977 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3978 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3979 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3980 // before any GC notifications are raised.
3981 g1mm()->update_sizes();
3982
3983 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3984 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3985 _gc_timer_stw->register_gc_end();
3986 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3987 }
3988 // It should now be safe to tell the concurrent mark thread to start
3989 // without its logging output interfering with the logging output
3990 // that came from the pause.
3991
3992 if (should_start_conc_mark) {
3993 // CAUTION: after the doConcurrentMark() call below,
3994 // the concurrent marking thread(s) could be running
3995 // concurrently with us. Make sure that anything after
3996 // this point does not assume that we are the only GC thread
3997 // running. Note: of course, the actual marking work will
3998 // not start until the safepoint itself is released in
3999 // SuspendibleThreadSet::desynchronize().
4000 doConcurrentMark();
4001 }
4002
4003 return true;
4004 }
4005
4006 void G1CollectedHeap::restore_preserved_marks() {
4007 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
4008 workers()->run_task(&rpm_task);
4009 }
4010
4011 void G1CollectedHeap::remove_self_forwarding_pointers() {
4012 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4013 workers()->run_task(&rsfp_task);
4014 }
4015
4016 void G1CollectedHeap::restore_after_evac_failure() {
4017 double remove_self_forwards_start = os::elapsedTime();
4018
4019 remove_self_forwarding_pointers();
4020 restore_preserved_marks();
4021
4022 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4023 }
4024
4025 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4026 if (!_evacuation_failed) {
4027 _evacuation_failed = true;
4028 }
4029
4030 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4031
4032 // We want to call the "for_promotion_failure" version only in the
4033 // case of a promotion failure.
4034 if (m->must_be_preserved_for_promotion_failure(obj)) {
4035 OopAndMarkOop elem(obj, m);
4036 _preserved_objs[worker_id].push(elem);
4037 }
4038 }
4039
4040 bool G1ParEvacuateFollowersClosure::offer_termination() {
4041 G1ParScanThreadState* const pss = par_scan_state();
4042 start_term_time();
4043 const bool res = terminator()->offer_termination();
4044 end_term_time();
4045 return res;
4046 }
4047
4048 void G1ParEvacuateFollowersClosure::do_void() {
4049 G1ParScanThreadState* const pss = par_scan_state();
4050 pss->trim_queue();
4051 do {
4052 pss->steal_and_trim_queue(queues());
4053 } while (!offer_termination());
4054 }
4055
4056 class G1ParTask : public AbstractGangTask {
4057 protected:
4058 G1CollectedHeap* _g1h;
4059 G1ParScanThreadStateSet* _pss;
4060 RefToScanQueueSet* _queues;
4061 G1RootProcessor* _root_processor;
4062 ParallelTaskTerminator _terminator;
4063 uint _n_workers;
4064
4065 public:
4066 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4067 : AbstractGangTask("G1 collection"),
4068 _g1h(g1h),
4069 _pss(per_thread_states),
4070 _queues(task_queues),
4071 _root_processor(root_processor),
4072 _terminator(n_workers, _queues),
4073 _n_workers(n_workers)
4074 {}
4075
4076 void work(uint worker_id) {
4077 if (worker_id >= _n_workers) return; // no work needed this round
4078
4079 double start_sec = os::elapsedTime();
4080 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4081
4082 {
4083 ResourceMark rm;
4084 HandleMark hm;
4085
4086 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4087
4088 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4089 pss->set_ref_processor(rp);
4090
4091 double start_strong_roots_sec = os::elapsedTime();
4092
4093 _root_processor->evacuate_roots(pss->closures(), worker_id);
4094
4095 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4096
4097 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4098 // treating the nmethods visited to act as roots for concurrent marking.
4099 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4100 // objects copied by the current evacuation.
4101 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4102 pss->closures()->weak_codeblobs(),
4103 worker_id);
4104
4105 _pss->add_cards_scanned(worker_id, cards_scanned);
4106
4107 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4108
4109 double term_sec = 0.0;
4110 size_t evac_term_attempts = 0;
4111 {
4112 double start = os::elapsedTime();
4113 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4114 evac.do_void();
4115
4116 evac_term_attempts = evac.term_attempts();
4117 term_sec = evac.term_time();
4118 double elapsed_sec = os::elapsedTime() - start;
4119 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4120 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4121 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4122 }
4123
4124 assert(pss->queue_is_empty(), "should be empty");
4125
4126 if (log_is_enabled(Debug, gc, task, stats)) {
4127 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4128 size_t lab_waste;
4129 size_t lab_undo_waste;
4130 pss->waste(lab_waste, lab_undo_waste);
4131 _g1h->print_termination_stats(worker_id,
4132 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4133 strong_roots_sec * 1000.0, /* strong roots time */
4134 term_sec * 1000.0, /* evac term time */
4135 evac_term_attempts, /* evac term attempts */
4136 lab_waste, /* alloc buffer waste */
4137 lab_undo_waste /* undo waste */
4138 );
4139 }
4140
4141 // Close the inner scope so that the ResourceMark and HandleMark
4142 // destructors are executed here and are included as part of the
4143 // "GC Worker Time".
4144 }
4145 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4146 }
4147 };
4148
4149 void G1CollectedHeap::print_termination_stats_hdr() {
4150 log_debug(gc, task, stats)("GC Termination Stats");
4151 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4152 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
4153 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4154 }
4155
4156 void G1CollectedHeap::print_termination_stats(uint worker_id,
4157 double elapsed_ms,
4158 double strong_roots_ms,
4159 double term_ms,
4160 size_t term_attempts,
4161 size_t alloc_buffer_waste,
4162 size_t undo_waste) const {
4163 log_debug(gc, task, stats)
4164 ("%3d %9.2f %9.2f %6.2f "
4165 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4166 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4167 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4168 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4169 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4170 alloc_buffer_waste * HeapWordSize / K,
4171 undo_waste * HeapWordSize / K);
4172 }
4173
4174 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4175 private:
4176 BoolObjectClosure* _is_alive;
4177 int _initial_string_table_size;
4178 int _initial_symbol_table_size;
4179
4180 bool _process_strings;
4181 int _strings_processed;
4182 int _strings_removed;
4183
4184 bool _process_symbols;
4185 int _symbols_processed;
4186 int _symbols_removed;
4187
4188 public:
4189 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4190 AbstractGangTask("String/Symbol Unlinking"),
4191 _is_alive(is_alive),
4192 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4193 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4194
4195 _initial_string_table_size = StringTable::the_table()->table_size();
4196 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4197 if (process_strings) {
4198 StringTable::clear_parallel_claimed_index();
4199 }
4200 if (process_symbols) {
4201 SymbolTable::clear_parallel_claimed_index();
4202 }
4203 }
4204
4205 ~G1StringSymbolTableUnlinkTask() {
4206 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4207 "claim value %d after unlink less than initial string table size %d",
4208 StringTable::parallel_claimed_index(), _initial_string_table_size);
4209 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4210 "claim value %d after unlink less than initial symbol table size %d",
4211 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4212
4213 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
4214 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4215 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4216 strings_processed(), strings_removed(),
4217 symbols_processed(), symbols_removed());
4218 }
4219
4220 void work(uint worker_id) {
4221 int strings_processed = 0;
4222 int strings_removed = 0;
4223 int symbols_processed = 0;
4224 int symbols_removed = 0;
4225 if (_process_strings) {
4226 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4227 Atomic::add(strings_processed, &_strings_processed);
4228 Atomic::add(strings_removed, &_strings_removed);
4229 }
4230 if (_process_symbols) {
4231 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4232 Atomic::add(symbols_processed, &_symbols_processed);
4233 Atomic::add(symbols_removed, &_symbols_removed);
4234 }
4235 }
4236
4237 size_t strings_processed() const { return (size_t)_strings_processed; }
4238 size_t strings_removed() const { return (size_t)_strings_removed; }
4239
4240 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4241 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4242 };
4243
4244 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4245 private:
4246 static Monitor* _lock;
4247
4248 BoolObjectClosure* const _is_alive;
4249 const bool _unloading_occurred;
4250 const uint _num_workers;
4251
4252 // Variables used to claim nmethods.
4253 nmethod* _first_nmethod;
4254 volatile nmethod* _claimed_nmethod;
4255
4256 // The list of nmethods that need to be processed by the second pass.
4257 volatile nmethod* _postponed_list;
4258 volatile uint _num_entered_barrier;
4259
4260 public:
4261 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4262 _is_alive(is_alive),
4263 _unloading_occurred(unloading_occurred),
4264 _num_workers(num_workers),
4265 _first_nmethod(NULL),
4266 _claimed_nmethod(NULL),
4267 _postponed_list(NULL),
4268 _num_entered_barrier(0)
4269 {
4270 nmethod::increase_unloading_clock();
4271 // Get first alive nmethod
4272 NMethodIterator iter = NMethodIterator();
4273 if(iter.next_alive()) {
4274 _first_nmethod = iter.method();
4275 }
4276 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4277 }
4278
4279 ~G1CodeCacheUnloadingTask() {
4280 CodeCache::verify_clean_inline_caches();
4281
4282 CodeCache::set_needs_cache_clean(false);
4283 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4284
4285 CodeCache::verify_icholder_relocations();
4286 }
4287
4288 private:
4289 void add_to_postponed_list(nmethod* nm) {
4290 nmethod* old;
4291 do {
4292 old = (nmethod*)_postponed_list;
4293 nm->set_unloading_next(old);
4294 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4295 }
4296
4297 void clean_nmethod(nmethod* nm) {
4298 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4299
4300 if (postponed) {
4301 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4302 add_to_postponed_list(nm);
4303 }
4304
4305 // Mark that this thread has been cleaned/unloaded.
4306 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4307 nm->set_unloading_clock(nmethod::global_unloading_clock());
4308 }
4309
4310 void clean_nmethod_postponed(nmethod* nm) {
4311 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4312 }
4313
4314 static const int MaxClaimNmethods = 16;
4315
4316 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4317 nmethod* first;
4318 NMethodIterator last;
4319
4320 do {
4321 *num_claimed_nmethods = 0;
4322
4323 first = (nmethod*)_claimed_nmethod;
4324 last = NMethodIterator(first);
4325
4326 if (first != NULL) {
4327
4328 for (int i = 0; i < MaxClaimNmethods; i++) {
4329 if (!last.next_alive()) {
4330 break;
4331 }
4332 claimed_nmethods[i] = last.method();
4333 (*num_claimed_nmethods)++;
4334 }
4335 }
4336
4337 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4338 }
4339
4340 nmethod* claim_postponed_nmethod() {
4341 nmethod* claim;
4342 nmethod* next;
4343
4344 do {
4345 claim = (nmethod*)_postponed_list;
4346 if (claim == NULL) {
4347 return NULL;
4348 }
4349
4350 next = claim->unloading_next();
4351
4352 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4353
4354 return claim;
4355 }
4356
4357 public:
4358 // Mark that we're done with the first pass of nmethod cleaning.
4359 void barrier_mark(uint worker_id) {
4360 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4361 _num_entered_barrier++;
4362 if (_num_entered_barrier == _num_workers) {
4363 ml.notify_all();
4364 }
4365 }
4366
4367 // See if we have to wait for the other workers to
4368 // finish their first-pass nmethod cleaning work.
4369 void barrier_wait(uint worker_id) {
4370 if (_num_entered_barrier < _num_workers) {
4371 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4372 while (_num_entered_barrier < _num_workers) {
4373 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4374 }
4375 }
4376 }
4377
4378 // Cleaning and unloading of nmethods. Some work has to be postponed
4379 // to the second pass, when we know which nmethods survive.
4380 void work_first_pass(uint worker_id) {
4381 // The first nmethods is claimed by the first worker.
4382 if (worker_id == 0 && _first_nmethod != NULL) {
4383 clean_nmethod(_first_nmethod);
4384 _first_nmethod = NULL;
4385 }
4386
4387 int num_claimed_nmethods;
4388 nmethod* claimed_nmethods[MaxClaimNmethods];
4389
4390 while (true) {
4391 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4392
4393 if (num_claimed_nmethods == 0) {
4394 break;
4395 }
4396
4397 for (int i = 0; i < num_claimed_nmethods; i++) {
4398 clean_nmethod(claimed_nmethods[i]);
4399 }
4400 }
4401 }
4402
4403 void work_second_pass(uint worker_id) {
4404 nmethod* nm;
4405 // Take care of postponed nmethods.
4406 while ((nm = claim_postponed_nmethod()) != NULL) {
4407 clean_nmethod_postponed(nm);
4408 }
4409 }
4410 };
4411
4412 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4413
4414 class G1KlassCleaningTask : public StackObj {
4415 BoolObjectClosure* _is_alive;
4416 volatile jint _clean_klass_tree_claimed;
4417 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4418
4419 public:
4420 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4421 _is_alive(is_alive),
4422 _clean_klass_tree_claimed(0),
4423 _klass_iterator() {
4424 }
4425
4426 private:
4427 bool claim_clean_klass_tree_task() {
4428 if (_clean_klass_tree_claimed) {
4429 return false;
4430 }
4431
4432 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4433 }
4434
4435 InstanceKlass* claim_next_klass() {
4436 Klass* klass;
4437 do {
4438 klass =_klass_iterator.next_klass();
4439 } while (klass != NULL && !klass->is_instance_klass());
4440
4441 // this can be null so don't call InstanceKlass::cast
4442 return static_cast<InstanceKlass*>(klass);
4443 }
4444
4445 public:
4446
4447 void clean_klass(InstanceKlass* ik) {
4448 ik->clean_weak_instanceklass_links(_is_alive);
4449 }
4450
4451 void work() {
4452 ResourceMark rm;
4453
4454 // One worker will clean the subklass/sibling klass tree.
4455 if (claim_clean_klass_tree_task()) {
4456 Klass::clean_subklass_tree(_is_alive);
4457 }
4458
4459 // All workers will help cleaning the classes,
4460 InstanceKlass* klass;
4461 while ((klass = claim_next_klass()) != NULL) {
4462 clean_klass(klass);
4463 }
4464 }
4465 };
4466
4467 // To minimize the remark pause times, the tasks below are done in parallel.
4468 class G1ParallelCleaningTask : public AbstractGangTask {
4469 private:
4470 G1StringSymbolTableUnlinkTask _string_symbol_task;
4471 G1CodeCacheUnloadingTask _code_cache_task;
4472 G1KlassCleaningTask _klass_cleaning_task;
4473
4474 public:
4475 // The constructor is run in the VMThread.
4476 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4477 AbstractGangTask("Parallel Cleaning"),
4478 _string_symbol_task(is_alive, process_strings, process_symbols),
4479 _code_cache_task(num_workers, is_alive, unloading_occurred),
4480 _klass_cleaning_task(is_alive) {
4481 }
4482
4483 // The parallel work done by all worker threads.
4484 void work(uint worker_id) {
4485 // Do first pass of code cache cleaning.
4486 _code_cache_task.work_first_pass(worker_id);
4487
4488 // Let the threads mark that the first pass is done.
4489 _code_cache_task.barrier_mark(worker_id);
4490
4491 // Clean the Strings and Symbols.
4492 _string_symbol_task.work(worker_id);
4493
4494 // Wait for all workers to finish the first code cache cleaning pass.
4495 _code_cache_task.barrier_wait(worker_id);
4496
4497 // Do the second code cache cleaning work, which realize on
4498 // the liveness information gathered during the first pass.
4499 _code_cache_task.work_second_pass(worker_id);
4500
4501 // Clean all klasses that were not unloaded.
4502 _klass_cleaning_task.work();
4503 }
4504 };
4505
4506
4507 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4508 bool process_strings,
4509 bool process_symbols,
4510 bool class_unloading_occurred) {
4511 uint n_workers = workers()->active_workers();
4512
4513 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4514 n_workers, class_unloading_occurred);
4515 workers()->run_task(&g1_unlink_task);
4516 }
4517
4518 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4519 bool process_strings, bool process_symbols) {
4520 {
4521 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4522 workers()->run_task(&g1_unlink_task);
4523 }
4524
4525 if (G1StringDedup::is_enabled()) {
4526 G1StringDedup::unlink(is_alive);
4527 }
4528 }
4529
4530 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4531 private:
4532 DirtyCardQueueSet* _queue;
4533 G1CollectedHeap* _g1h;
4534 public:
4535 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4536 _queue(queue), _g1h(g1h) { }
4537
4538 virtual void work(uint worker_id) {
4539 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4540 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4541
4542 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4543 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4544
4545 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4546 }
4547 };
4548
4549 void G1CollectedHeap::redirty_logged_cards() {
4550 double redirty_logged_cards_start = os::elapsedTime();
4551
4552 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4553 dirty_card_queue_set().reset_for_par_iteration();
4554 workers()->run_task(&redirty_task);
4555
4556 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4557 dcq.merge_bufferlists(&dirty_card_queue_set());
4558 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4559
4560 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4561 }
4562
4563 // Weak Reference Processing support
4564
4565 // An always "is_alive" closure that is used to preserve referents.
4566 // If the object is non-null then it's alive. Used in the preservation
4567 // of referent objects that are pointed to by reference objects
4568 // discovered by the CM ref processor.
4569 class G1AlwaysAliveClosure: public BoolObjectClosure {
4570 G1CollectedHeap* _g1;
4571 public:
4572 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4573 bool do_object_b(oop p) {
4574 if (p != NULL) {
4575 return true;
4576 }
4577 return false;
4578 }
4579 };
4580
4581 bool G1STWIsAliveClosure::do_object_b(oop p) {
4582 // An object is reachable if it is outside the collection set,
4583 // or is inside and copied.
4584 return !_g1->is_in_cset(p) || p->is_forwarded();
4585 }
4586
4587 // Non Copying Keep Alive closure
4588 class G1KeepAliveClosure: public OopClosure {
4589 G1CollectedHeap* _g1;
4590 public:
4591 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4592 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4593 void do_oop(oop* p) {
4594 oop obj = *p;
4595 assert(obj != NULL, "the caller should have filtered out NULL values");
4596
4597 const InCSetState cset_state = _g1->in_cset_state(obj);
4598 if (!cset_state.is_in_cset_or_humongous()) {
4599 return;
4600 }
4601 if (cset_state.is_in_cset()) {
4602 assert( obj->is_forwarded(), "invariant" );
4603 *p = obj->forwardee();
4604 } else {
4605 assert(!obj->is_forwarded(), "invariant" );
4606 assert(cset_state.is_humongous(),
4607 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4608 _g1->set_humongous_is_live(obj);
4609 }
4610 }
4611 };
4612
4613 // Copying Keep Alive closure - can be called from both
4614 // serial and parallel code as long as different worker
4615 // threads utilize different G1ParScanThreadState instances
4616 // and different queues.
4617
4618 class G1CopyingKeepAliveClosure: public OopClosure {
4619 G1CollectedHeap* _g1h;
4620 OopClosure* _copy_non_heap_obj_cl;
4621 G1ParScanThreadState* _par_scan_state;
4622
4623 public:
4624 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4625 OopClosure* non_heap_obj_cl,
4626 G1ParScanThreadState* pss):
4627 _g1h(g1h),
4628 _copy_non_heap_obj_cl(non_heap_obj_cl),
4629 _par_scan_state(pss)
4630 {}
4631
4632 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4633 virtual void do_oop( oop* p) { do_oop_work(p); }
4634
4635 template <class T> void do_oop_work(T* p) {
4636 oop obj = oopDesc::load_decode_heap_oop(p);
4637
4638 if (_g1h->is_in_cset_or_humongous(obj)) {
4639 // If the referent object has been forwarded (either copied
4640 // to a new location or to itself in the event of an
4641 // evacuation failure) then we need to update the reference
4642 // field and, if both reference and referent are in the G1
4643 // heap, update the RSet for the referent.
4644 //
4645 // If the referent has not been forwarded then we have to keep
4646 // it alive by policy. Therefore we have copy the referent.
4647 //
4648 // If the reference field is in the G1 heap then we can push
4649 // on the PSS queue. When the queue is drained (after each
4650 // phase of reference processing) the object and it's followers
4651 // will be copied, the reference field set to point to the
4652 // new location, and the RSet updated. Otherwise we need to
4653 // use the the non-heap or metadata closures directly to copy
4654 // the referent object and update the pointer, while avoiding
4655 // updating the RSet.
4656
4657 if (_g1h->is_in_g1_reserved(p)) {
4658 _par_scan_state->push_on_queue(p);
4659 } else {
4660 assert(!Metaspace::contains((const void*)p),
4661 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4662 _copy_non_heap_obj_cl->do_oop(p);
4663 }
4664 }
4665 }
4666 };
4667
4668 // Serial drain queue closure. Called as the 'complete_gc'
4669 // closure for each discovered list in some of the
4670 // reference processing phases.
4671
4672 class G1STWDrainQueueClosure: public VoidClosure {
4673 protected:
4674 G1CollectedHeap* _g1h;
4675 G1ParScanThreadState* _par_scan_state;
4676
4677 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4678
4679 public:
4680 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4681 _g1h(g1h),
4682 _par_scan_state(pss)
4683 { }
4684
4685 void do_void() {
4686 G1ParScanThreadState* const pss = par_scan_state();
4687 pss->trim_queue();
4688 }
4689 };
4690
4691 // Parallel Reference Processing closures
4692
4693 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4694 // processing during G1 evacuation pauses.
4695
4696 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4697 private:
4698 G1CollectedHeap* _g1h;
4699 G1ParScanThreadStateSet* _pss;
4700 RefToScanQueueSet* _queues;
4701 WorkGang* _workers;
4702 uint _active_workers;
4703
4704 public:
4705 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4706 G1ParScanThreadStateSet* per_thread_states,
4707 WorkGang* workers,
4708 RefToScanQueueSet *task_queues,
4709 uint n_workers) :
4710 _g1h(g1h),
4711 _pss(per_thread_states),
4712 _queues(task_queues),
4713 _workers(workers),
4714 _active_workers(n_workers)
4715 {
4716 assert(n_workers > 0, "shouldn't call this otherwise");
4717 }
4718
4719 // Executes the given task using concurrent marking worker threads.
4720 virtual void execute(ProcessTask& task);
4721 virtual void execute(EnqueueTask& task);
4722 };
4723
4724 // Gang task for possibly parallel reference processing
4725
4726 class G1STWRefProcTaskProxy: public AbstractGangTask {
4727 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4728 ProcessTask& _proc_task;
4729 G1CollectedHeap* _g1h;
4730 G1ParScanThreadStateSet* _pss;
4731 RefToScanQueueSet* _task_queues;
4732 ParallelTaskTerminator* _terminator;
4733
4734 public:
4735 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4736 G1CollectedHeap* g1h,
4737 G1ParScanThreadStateSet* per_thread_states,
4738 RefToScanQueueSet *task_queues,
4739 ParallelTaskTerminator* terminator) :
4740 AbstractGangTask("Process reference objects in parallel"),
4741 _proc_task(proc_task),
4742 _g1h(g1h),
4743 _pss(per_thread_states),
4744 _task_queues(task_queues),
4745 _terminator(terminator)
4746 {}
4747
4748 virtual void work(uint worker_id) {
4749 // The reference processing task executed by a single worker.
4750 ResourceMark rm;
4751 HandleMark hm;
4752
4753 G1STWIsAliveClosure is_alive(_g1h);
4754
4755 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4756 pss->set_ref_processor(NULL);
4757
4758 // Keep alive closure.
4759 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4760
4761 // Complete GC closure
4762 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4763
4764 // Call the reference processing task's work routine.
4765 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4766
4767 // Note we cannot assert that the refs array is empty here as not all
4768 // of the processing tasks (specifically phase2 - pp2_work) execute
4769 // the complete_gc closure (which ordinarily would drain the queue) so
4770 // the queue may not be empty.
4771 }
4772 };
4773
4774 // Driver routine for parallel reference processing.
4775 // Creates an instance of the ref processing gang
4776 // task and has the worker threads execute it.
4777 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4778 assert(_workers != NULL, "Need parallel worker threads.");
4779
4780 ParallelTaskTerminator terminator(_active_workers, _queues);
4781 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4782
4783 _workers->run_task(&proc_task_proxy);
4784 }
4785
4786 // Gang task for parallel reference enqueueing.
4787
4788 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4789 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4790 EnqueueTask& _enq_task;
4791
4792 public:
4793 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4794 AbstractGangTask("Enqueue reference objects in parallel"),
4795 _enq_task(enq_task)
4796 { }
4797
4798 virtual void work(uint worker_id) {
4799 _enq_task.work(worker_id);
4800 }
4801 };
4802
4803 // Driver routine for parallel reference enqueueing.
4804 // Creates an instance of the ref enqueueing gang
4805 // task and has the worker threads execute it.
4806
4807 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4808 assert(_workers != NULL, "Need parallel worker threads.");
4809
4810 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4811
4812 _workers->run_task(&enq_task_proxy);
4813 }
4814
4815 // End of weak reference support closures
4816
4817 // Abstract task used to preserve (i.e. copy) any referent objects
4818 // that are in the collection set and are pointed to by reference
4819 // objects discovered by the CM ref processor.
4820
4821 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4822 protected:
4823 G1CollectedHeap* _g1h;
4824 G1ParScanThreadStateSet* _pss;
4825 RefToScanQueueSet* _queues;
4826 ParallelTaskTerminator _terminator;
4827 uint _n_workers;
4828
4829 public:
4830 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4831 AbstractGangTask("ParPreserveCMReferents"),
4832 _g1h(g1h),
4833 _pss(per_thread_states),
4834 _queues(task_queues),
4835 _terminator(workers, _queues),
4836 _n_workers(workers)
4837 { }
4838
4839 void work(uint worker_id) {
4840 ResourceMark rm;
4841 HandleMark hm;
4842
4843 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4844 pss->set_ref_processor(NULL);
4845 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4846
4847 // Is alive closure
4848 G1AlwaysAliveClosure always_alive(_g1h);
4849
4850 // Copying keep alive closure. Applied to referent objects that need
4851 // to be copied.
4852 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4853
4854 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4855
4856 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4857 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4858
4859 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4860 // So this must be true - but assert just in case someone decides to
4861 // change the worker ids.
4862 assert(worker_id < limit, "sanity");
4863 assert(!rp->discovery_is_atomic(), "check this code");
4864
4865 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4866 for (uint idx = worker_id; idx < limit; idx += stride) {
4867 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4868
4869 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4870 while (iter.has_next()) {
4871 // Since discovery is not atomic for the CM ref processor, we
4872 // can see some null referent objects.
4873 iter.load_ptrs(DEBUG_ONLY(true));
4874 oop ref = iter.obj();
4875
4876 // This will filter nulls.
4877 if (iter.is_referent_alive()) {
4878 iter.make_referent_alive();
4879 }
4880 iter.move_to_next();
4881 }
4882 }
4883
4884 // Drain the queue - which may cause stealing
4885 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4886 drain_queue.do_void();
4887 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4888 assert(pss->queue_is_empty(), "should be");
4889 }
4890 };
4891
4892 void G1CollectedHeap::process_weak_jni_handles() {
4893 double ref_proc_start = os::elapsedTime();
4894
4895 G1STWIsAliveClosure is_alive(this);
4896 G1KeepAliveClosure keep_alive(this);
4897 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4898
4899 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4900 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4901 }
4902
4903 // Weak Reference processing during an evacuation pause (part 1).
4904 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4905 double ref_proc_start = os::elapsedTime();
4906
4907 ReferenceProcessor* rp = _ref_processor_stw;
4908 assert(rp->discovery_enabled(), "should have been enabled");
4909
4910 // Any reference objects, in the collection set, that were 'discovered'
4911 // by the CM ref processor should have already been copied (either by
4912 // applying the external root copy closure to the discovered lists, or
4913 // by following an RSet entry).
4914 //
4915 // But some of the referents, that are in the collection set, that these
4916 // reference objects point to may not have been copied: the STW ref
4917 // processor would have seen that the reference object had already
4918 // been 'discovered' and would have skipped discovering the reference,
4919 // but would not have treated the reference object as a regular oop.
4920 // As a result the copy closure would not have been applied to the
4921 // referent object.
4922 //
4923 // We need to explicitly copy these referent objects - the references
4924 // will be processed at the end of remarking.
4925 //
4926 // We also need to do this copying before we process the reference
4927 // objects discovered by the STW ref processor in case one of these
4928 // referents points to another object which is also referenced by an
4929 // object discovered by the STW ref processor.
4930
4931 uint no_of_gc_workers = workers()->active_workers();
4932
4933 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4934 per_thread_states,
4935 no_of_gc_workers,
4936 _task_queues);
4937
4938 workers()->run_task(&keep_cm_referents);
4939
4940 // Closure to test whether a referent is alive.
4941 G1STWIsAliveClosure is_alive(this);
4942
4943 // Even when parallel reference processing is enabled, the processing
4944 // of JNI refs is serial and performed serially by the current thread
4945 // rather than by a worker. The following PSS will be used for processing
4946 // JNI refs.
4947
4948 // Use only a single queue for this PSS.
4949 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4950 pss->set_ref_processor(NULL);
4951 assert(pss->queue_is_empty(), "pre-condition");
4952
4953 // Keep alive closure.
4954 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4955
4956 // Serial Complete GC closure
4957 G1STWDrainQueueClosure drain_queue(this, pss);
4958
4959 // Setup the soft refs policy...
4960 rp->setup_policy(false);
4961
4962 ReferenceProcessorStats stats;
4963 if (!rp->processing_is_mt()) {
4964 // Serial reference processing...
4965 stats = rp->process_discovered_references(&is_alive,
4966 &keep_alive,
4967 &drain_queue,
4968 NULL,
4969 _gc_timer_stw);
4970 } else {
4971 // Parallel reference processing
4972 assert(rp->num_q() == no_of_gc_workers, "sanity");
4973 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4974
4975 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4976 stats = rp->process_discovered_references(&is_alive,
4977 &keep_alive,
4978 &drain_queue,
4979 &par_task_executor,
4980 _gc_timer_stw);
4981 }
4982
4983 _gc_tracer_stw->report_gc_reference_stats(stats);
4984
4985 // We have completed copying any necessary live referent objects.
4986 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4987
4988 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4989 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4990 }
4991
4992 // Weak Reference processing during an evacuation pause (part 2).
4993 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4994 double ref_enq_start = os::elapsedTime();
4995
4996 ReferenceProcessor* rp = _ref_processor_stw;
4997 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4998
4999 // Now enqueue any remaining on the discovered lists on to
5000 // the pending list.
5001 if (!rp->processing_is_mt()) {
5002 // Serial reference processing...
5003 rp->enqueue_discovered_references();
5004 } else {
5005 // Parallel reference enqueueing
5006
5007 uint n_workers = workers()->active_workers();
5008
5009 assert(rp->num_q() == n_workers, "sanity");
5010 assert(n_workers <= rp->max_num_q(), "sanity");
5011
5012 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5013 rp->enqueue_discovered_references(&par_task_executor);
5014 }
5015
5016 rp->verify_no_references_recorded();
5017 assert(!rp->discovery_enabled(), "should have been disabled");
5018
5019 // FIXME
5020 // CM's reference processing also cleans up the string and symbol tables.
5021 // Should we do that here also? We could, but it is a serial operation
5022 // and could significantly increase the pause time.
5023
5024 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5025 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5026 }
5027
5028 void G1CollectedHeap::pre_evacuate_collection_set() {
5029 _expand_heap_after_alloc_failure = true;
5030 _evacuation_failed = false;
5031
5032 // Disable the hot card cache.
5033 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5034 hot_card_cache->reset_hot_cache_claimed_index();
5035 hot_card_cache->set_use_cache(false);
5036
5037 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5038 }
5039
5040 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5041 // Should G1EvacuationFailureALot be in effect for this GC?
5042 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5043
5044 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5045 double start_par_time_sec = os::elapsedTime();
5046 double end_par_time_sec;
5047
5048 {
5049 const uint n_workers = workers()->active_workers();
5050 G1RootProcessor root_processor(this, n_workers);
5051 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5052 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5053 if (collector_state()->during_initial_mark_pause()) {
5054 ClassLoaderDataGraph::clear_claimed_marks();
5055 }
5056
5057 print_termination_stats_hdr();
5058
5059 workers()->run_task(&g1_par_task);
5060 end_par_time_sec = os::elapsedTime();
5061
5062 // Closing the inner scope will execute the destructor
5063 // for the G1RootProcessor object. We record the current
5064 // elapsed time before closing the scope so that time
5065 // taken for the destructor is NOT included in the
5066 // reported parallel time.
5067 }
5068
5069 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5070
5071 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5072 phase_times->record_par_time(par_time_ms);
5073
5074 double code_root_fixup_time_ms =
5075 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5076 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5077 }
5078
5079 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5080 // Process any discovered reference objects - we have
5081 // to do this _before_ we retire the GC alloc regions
5082 // as we may have to copy some 'reachable' referent
5083 // objects (and their reachable sub-graphs) that were
5084 // not copied during the pause.
5085 if (g1_policy()->should_process_references()) {
5086 process_discovered_references(per_thread_states);
5087 } else {
5088 ref_processor_stw()->verify_no_references_recorded();
5089 process_weak_jni_handles();
5090 }
5091
5092 if (G1StringDedup::is_enabled()) {
5093 double fixup_start = os::elapsedTime();
5094
5095 G1STWIsAliveClosure is_alive(this);
5096 G1KeepAliveClosure keep_alive(this);
5097 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5098
5099 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5100 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5101 }
5102
5103 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5104
5105 if (evacuation_failed()) {
5106 restore_after_evac_failure();
5107
5108 // Reset the G1EvacuationFailureALot counters and flags
5109 // Note: the values are reset only when an actual
5110 // evacuation failure occurs.
5111 NOT_PRODUCT(reset_evacuation_should_fail();)
5112 }
5113
5114 // Enqueue any remaining references remaining on the STW
5115 // reference processor's discovered lists. We need to do
5116 // this after the card table is cleaned (and verified) as
5117 // the act of enqueueing entries on to the pending list
5118 // will log these updates (and dirty their associated
5119 // cards). We need these updates logged to update any
5120 // RSets.
5121 if (g1_policy()->should_process_references()) {
5122 enqueue_discovered_references(per_thread_states);
5123 } else {
5124 g1_policy()->phase_times()->record_ref_enq_time(0);
5125 }
5126
5127 _allocator->release_gc_alloc_regions(evacuation_info);
5128
5129 per_thread_states->flush();
5130
5131 record_obj_copy_mem_stats();
5132
5133 _survivor_evac_stats.adjust_desired_plab_sz();
5134 _old_evac_stats.adjust_desired_plab_sz();
5135
5136 // Reset and re-enable the hot card cache.
5137 // Note the counts for the cards in the regions in the
5138 // collection set are reset when the collection set is freed.
5139 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5140 hot_card_cache->reset_hot_cache();
5141 hot_card_cache->set_use_cache(true);
5142
5143 purge_code_root_memory();
5144
5145 redirty_logged_cards();
5146 #if defined(COMPILER2) || INCLUDE_JVMCI
5147 DerivedPointerTable::update_pointers();
5148 #endif
5149 }
5150
5151 void G1CollectedHeap::record_obj_copy_mem_stats() {
5152 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5153
5154 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5155 create_g1_evac_summary(&_old_evac_stats));
5156 }
5157
5158 void G1CollectedHeap::free_region(HeapRegion* hr,
5159 FreeRegionList* free_list,
5160 bool par,
5161 bool locked) {
5162 assert(!hr->is_free(), "the region should not be free");
5163 assert(!hr->is_empty(), "the region should not be empty");
5164 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5165 assert(free_list != NULL, "pre-condition");
5166
5167 if (G1VerifyBitmaps) {
5168 MemRegion mr(hr->bottom(), hr->end());
5169 concurrent_mark()->clearRangePrevBitmap(mr);
5170 }
5171
5172 // Clear the card counts for this region.
5173 // Note: we only need to do this if the region is not young
5174 // (since we don't refine cards in young regions).
5175 if (!hr->is_young()) {
5176 _cg1r->hot_card_cache()->reset_card_counts(hr);
5177 }
5178 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5179 free_list->add_ordered(hr);
5180 }
5181
5182 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5183 FreeRegionList* free_list,
5184 bool par) {
5185 assert(hr->is_humongous(), "this is only for humongous regions");
5186 assert(free_list != NULL, "pre-condition");
5187 hr->clear_humongous();
5188 free_region(hr, free_list, par);
5189 }
5190
5191 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5192 const HeapRegionSetCount& humongous_regions_removed) {
5193 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5194 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5195 _old_set.bulk_remove(old_regions_removed);
5196 _humongous_set.bulk_remove(humongous_regions_removed);
5197 }
5198
5199 }
5200
5201 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5202 assert(list != NULL, "list can't be null");
5203 if (!list->is_empty()) {
5204 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5205 _hrm.insert_list_into_free_list(list);
5206 }
5207 }
5208
5209 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5210 decrease_used(bytes);
5211 }
5212
5213 class G1ParCleanupCTTask : public AbstractGangTask {
5214 G1SATBCardTableModRefBS* _ct_bs;
5215 G1CollectedHeap* _g1h;
5216 HeapRegion* volatile _su_head;
5217 public:
5218 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5219 G1CollectedHeap* g1h) :
5220 AbstractGangTask("G1 Par Cleanup CT Task"),
5221 _ct_bs(ct_bs), _g1h(g1h) { }
5222
5223 void work(uint worker_id) {
5224 HeapRegion* r;
5225 while (r = _g1h->pop_dirty_cards_region()) {
5226 clear_cards(r);
5227 }
5228 }
5229
5230 void clear_cards(HeapRegion* r) {
5231 // Cards of the survivors should have already been dirtied.
5232 if (!r->is_survivor()) {
5233 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5234 }
5235 }
5236 };
5237
5238 #ifndef PRODUCT
5239 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5240 G1CollectedHeap* _g1h;
5241 G1SATBCardTableModRefBS* _ct_bs;
5242 public:
5243 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5244 : _g1h(g1h), _ct_bs(ct_bs) { }
5245 virtual bool doHeapRegion(HeapRegion* r) {
5246 if (r->is_survivor()) {
5247 _g1h->verify_dirty_region(r);
5248 } else {
5249 _g1h->verify_not_dirty_region(r);
5250 }
5251 return false;
5252 }
5253 };
5254
5255 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5256 // All of the region should be clean.
5257 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5258 MemRegion mr(hr->bottom(), hr->end());
5259 ct_bs->verify_not_dirty_region(mr);
5260 }
5261
5262 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5263 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5264 // dirty allocated blocks as they allocate them. The thread that
5265 // retires each region and replaces it with a new one will do a
5266 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5267 // not dirty that area (one less thing to have to do while holding
5268 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5269 // is dirty.
5270 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5271 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5272 if (hr->is_young()) {
5273 ct_bs->verify_g1_young_region(mr);
5274 } else {
5275 ct_bs->verify_dirty_region(mr);
5276 }
5277 }
5278
5279 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5280 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5281 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5282 verify_dirty_region(hr);
5283 }
5284 }
5285
5286 void G1CollectedHeap::verify_dirty_young_regions() {
5287 verify_dirty_young_list(_young_list->first_region());
5288 }
5289
5290 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5291 HeapWord* tams, HeapWord* end) {
5292 guarantee(tams <= end,
5293 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5294 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5295 if (result < end) {
5296 log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5297 log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5298 return false;
5299 }
5300 return true;
5301 }
5302
5303 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5304 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5305 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5306
5307 HeapWord* bottom = hr->bottom();
5308 HeapWord* ptams = hr->prev_top_at_mark_start();
5309 HeapWord* ntams = hr->next_top_at_mark_start();
5310 HeapWord* end = hr->end();
5311
5312 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5313
5314 bool res_n = true;
5315 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5316 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5317 // if we happen to be in that state.
5318 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5319 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5320 }
5321 if (!res_p || !res_n) {
5322 log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5323 log_info(gc, verify)("#### Caller: %s", caller);
5324 return false;
5325 }
5326 return true;
5327 }
5328
5329 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5330 if (!G1VerifyBitmaps) return;
5331
5332 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5333 }
5334
5335 class G1VerifyBitmapClosure : public HeapRegionClosure {
5336 private:
5337 const char* _caller;
5338 G1CollectedHeap* _g1h;
5339 bool _failures;
5340
5341 public:
5342 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5343 _caller(caller), _g1h(g1h), _failures(false) { }
5344
5345 bool failures() { return _failures; }
5346
5347 virtual bool doHeapRegion(HeapRegion* hr) {
5348 bool result = _g1h->verify_bitmaps(_caller, hr);
5349 if (!result) {
5350 _failures = true;
5351 }
5352 return false;
5353 }
5354 };
5355
5356 void G1CollectedHeap::check_bitmaps(const char* caller) {
5357 if (!G1VerifyBitmaps) return;
5358
5359 G1VerifyBitmapClosure cl(caller, this);
5360 heap_region_iterate(&cl);
5361 guarantee(!cl.failures(), "bitmap verification");
5362 }
5363
5364 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5365 private:
5366 bool _failures;
5367 public:
5368 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5369
5370 virtual bool doHeapRegion(HeapRegion* hr) {
5371 uint i = hr->hrm_index();
5372 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5373 if (hr->is_humongous()) {
5374 if (hr->in_collection_set()) {
5375 log_info(gc, verify)("\n## humongous region %u in CSet", i);
5376 _failures = true;
5377 return true;
5378 }
5379 if (cset_state.is_in_cset()) {
5380 log_info(gc, verify)("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5381 _failures = true;
5382 return true;
5383 }
5384 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5385 log_info(gc, verify)("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5386 _failures = true;
5387 return true;
5388 }
5389 } else {
5390 if (cset_state.is_humongous()) {
5391 log_info(gc, verify)("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5392 _failures = true;
5393 return true;
5394 }
5395 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5396 log_info(gc, verify)("\n## in CSet %d / cset state %d inconsistency for region %u",
5397 hr->in_collection_set(), cset_state.value(), i);
5398 _failures = true;
5399 return true;
5400 }
5401 if (cset_state.is_in_cset()) {
5402 if (hr->is_young() != (cset_state.is_young())) {
5403 log_info(gc, verify)("\n## is_young %d / cset state %d inconsistency for region %u",
5404 hr->is_young(), cset_state.value(), i);
5405 _failures = true;
5406 return true;
5407 }
5408 if (hr->is_old() != (cset_state.is_old())) {
5409 log_info(gc, verify)("\n## is_old %d / cset state %d inconsistency for region %u",
5410 hr->is_old(), cset_state.value(), i);
5411 _failures = true;
5412 return true;
5413 }
5414 }
5415 }
5416 return false;
5417 }
5418
5419 bool failures() const { return _failures; }
5420 };
5421
5422 bool G1CollectedHeap::check_cset_fast_test() {
5423 G1CheckCSetFastTableClosure cl;
5424 _hrm.iterate(&cl);
5425 return !cl.failures();
5426 }
5427 #endif // PRODUCT
5428
5429 void G1CollectedHeap::cleanUpCardTable() {
5430 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5431 double start = os::elapsedTime();
5432
5433 {
5434 // Iterate over the dirty cards region list.
5435 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5436
5437 workers()->run_task(&cleanup_task);
5438 #ifndef PRODUCT
5439 if (G1VerifyCTCleanup || VerifyAfterGC) {
5440 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5441 heap_region_iterate(&cleanup_verifier);
5442 }
5443 #endif
5444 }
5445
5446 double elapsed = os::elapsedTime() - start;
5447 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5448 }
5449
5450 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5451 size_t pre_used = 0;
5452 FreeRegionList local_free_list("Local List for CSet Freeing");
5453
5454 double young_time_ms = 0.0;
5455 double non_young_time_ms = 0.0;
5456
5457 // Since the collection set is a superset of the the young list,
5458 // all we need to do to clear the young list is clear its
5459 // head and length, and unlink any young regions in the code below
5460 _young_list->clear();
5461
5462 G1CollectorPolicy* policy = g1_policy();
5463
5464 double start_sec = os::elapsedTime();
5465 bool non_young = true;
5466
5467 HeapRegion* cur = cs_head;
5468 int age_bound = -1;
5469 size_t rs_lengths = 0;
5470
5471 while (cur != NULL) {
5472 assert(!is_on_master_free_list(cur), "sanity");
5473 if (non_young) {
5474 if (cur->is_young()) {
5475 double end_sec = os::elapsedTime();
5476 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5477 non_young_time_ms += elapsed_ms;
5478
5479 start_sec = os::elapsedTime();
5480 non_young = false;
5481 }
5482 } else {
5483 if (!cur->is_young()) {
5484 double end_sec = os::elapsedTime();
5485 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5486 young_time_ms += elapsed_ms;
5487
5488 start_sec = os::elapsedTime();
5489 non_young = true;
5490 }
5491 }
5492
5493 rs_lengths += cur->rem_set()->occupied_locked();
5494
5495 HeapRegion* next = cur->next_in_collection_set();
5496 assert(cur->in_collection_set(), "bad CS");
5497 cur->set_next_in_collection_set(NULL);
5498 clear_in_cset(cur);
5499
5500 if (cur->is_young()) {
5501 int index = cur->young_index_in_cset();
5502 assert(index != -1, "invariant");
5503 assert((uint) index < policy->young_cset_region_length(), "invariant");
5504 size_t words_survived = surviving_young_words[index];
5505 cur->record_surv_words_in_group(words_survived);
5506
5507 // At this point the we have 'popped' cur from the collection set
5508 // (linked via next_in_collection_set()) but it is still in the
5509 // young list (linked via next_young_region()). Clear the
5510 // _next_young_region field.
5511 cur->set_next_young_region(NULL);
5512 } else {
5513 int index = cur->young_index_in_cset();
5514 assert(index == -1, "invariant");
5515 }
5516
5517 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5518 (!cur->is_young() && cur->young_index_in_cset() == -1),
5519 "invariant" );
5520
5521 if (!cur->evacuation_failed()) {
5522 MemRegion used_mr = cur->used_region();
5523
5524 // And the region is empty.
5525 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5526 pre_used += cur->used();
5527 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5528 } else {
5529 cur->uninstall_surv_rate_group();
5530 if (cur->is_young()) {
5531 cur->set_young_index_in_cset(-1);
5532 }
5533 cur->set_evacuation_failed(false);
5534 // When moving a young gen region to old gen, we "allocate" that whole region
5535 // there. This is in addition to any already evacuated objects. Notify the
5536 // policy about that.
5537 // Old gen regions do not cause an additional allocation: both the objects
5538 // still in the region and the ones already moved are accounted for elsewhere.
5539 if (cur->is_young()) {
5540 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5541 }
5542 // The region is now considered to be old.
5543 cur->set_old();
5544 // Do some allocation statistics accounting. Regions that failed evacuation
5545 // are always made old, so there is no need to update anything in the young
5546 // gen statistics, but we need to update old gen statistics.
5547 size_t used_words = cur->marked_bytes() / HeapWordSize;
5548 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5549 _old_set.add(cur);
5550 evacuation_info.increment_collectionset_used_after(cur->used());
5551 }
5552 cur = next;
5553 }
5554
5555 evacuation_info.set_regions_freed(local_free_list.length());
5556 policy->record_max_rs_lengths(rs_lengths);
5557 policy->cset_regions_freed();
5558
5559 double end_sec = os::elapsedTime();
5560 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5561
5562 if (non_young) {
5563 non_young_time_ms += elapsed_ms;
5564 } else {
5565 young_time_ms += elapsed_ms;
5566 }
5567
5568 prepend_to_freelist(&local_free_list);
5569 decrement_summary_bytes(pre_used);
5570 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5571 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5572 }
5573
5574 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5575 private:
5576 FreeRegionList* _free_region_list;
5577 HeapRegionSet* _proxy_set;
5578 HeapRegionSetCount _humongous_regions_removed;
5579 size_t _freed_bytes;
5580 public:
5581
5582 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5583 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5584 }
5585
5586 virtual bool doHeapRegion(HeapRegion* r) {
5587 if (!r->is_starts_humongous()) {
5588 return false;
5589 }
5590
5591 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5592
5593 oop obj = (oop)r->bottom();
5594 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5595
5596 // The following checks whether the humongous object is live are sufficient.
5597 // The main additional check (in addition to having a reference from the roots
5598 // or the young gen) is whether the humongous object has a remembered set entry.
5599 //
5600 // A humongous object cannot be live if there is no remembered set for it
5601 // because:
5602 // - there can be no references from within humongous starts regions referencing
5603 // the object because we never allocate other objects into them.
5604 // (I.e. there are no intra-region references that may be missed by the
5605 // remembered set)
5606 // - as soon there is a remembered set entry to the humongous starts region
5607 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5608 // until the end of a concurrent mark.
5609 //
5610 // It is not required to check whether the object has been found dead by marking
5611 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5612 // all objects allocated during that time are considered live.
5613 // SATB marking is even more conservative than the remembered set.
5614 // So if at this point in the collection there is no remembered set entry,
5615 // nobody has a reference to it.
5616 // At the start of collection we flush all refinement logs, and remembered sets
5617 // are completely up-to-date wrt to references to the humongous object.
5618 //
5619 // Other implementation considerations:
5620 // - never consider object arrays at this time because they would pose
5621 // considerable effort for cleaning up the the remembered sets. This is
5622 // required because stale remembered sets might reference locations that
5623 // are currently allocated into.
5624 uint region_idx = r->hrm_index();
5625 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5626 !r->rem_set()->is_empty()) {
5627 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",
5628 region_idx,
5629 (size_t)obj->size() * HeapWordSize,
5630 p2i(r->bottom()),
5631 r->rem_set()->occupied(),
5632 r->rem_set()->strong_code_roots_list_length(),
5633 next_bitmap->isMarked(r->bottom()),
5634 g1h->is_humongous_reclaim_candidate(region_idx),
5635 obj->is_typeArray()
5636 );
5637 return false;
5638 }
5639
5640 guarantee(obj->is_typeArray(),
5641 "Only eagerly reclaiming type arrays is supported, but the object "
5642 PTR_FORMAT " is not.", p2i(r->bottom()));
5643
5644 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",
5645 region_idx,
5646 (size_t)obj->size() * HeapWordSize,
5647 p2i(r->bottom()),
5648 r->rem_set()->occupied(),
5649 r->rem_set()->strong_code_roots_list_length(),
5650 next_bitmap->isMarked(r->bottom()),
5651 g1h->is_humongous_reclaim_candidate(region_idx),
5652 obj->is_typeArray()
5653 );
5654
5655 // Need to clear mark bit of the humongous object if already set.
5656 if (next_bitmap->isMarked(r->bottom())) {
5657 next_bitmap->clear(r->bottom());
5658 }
5659 do {
5660 HeapRegion* next = g1h->next_region_in_humongous(r);
5661 _freed_bytes += r->used();
5662 r->set_containing_set(NULL);
5663 _humongous_regions_removed.increment(1u, r->capacity());
5664 g1h->free_humongous_region(r, _free_region_list, false);
5665 r = next;
5666 } while (r != NULL);
5667
5668 return false;
5669 }
5670
5671 HeapRegionSetCount& humongous_free_count() {
5672 return _humongous_regions_removed;
5673 }
5674
5675 size_t bytes_freed() const {
5676 return _freed_bytes;
5677 }
5678
5679 size_t humongous_reclaimed() const {
5680 return _humongous_regions_removed.length();
5681 }
5682 };
5683
5684 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5685 assert_at_safepoint(true);
5686
5687 if (!G1EagerReclaimHumongousObjects ||
5688 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5689 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5690 return;
5691 }
5692
5693 double start_time = os::elapsedTime();
5694
5695 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5696
5697 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5698 heap_region_iterate(&cl);
5699
5700 HeapRegionSetCount empty_set;
5701 remove_from_old_sets(empty_set, cl.humongous_free_count());
5702
5703 G1HRPrinter* hrp = hr_printer();
5704 if (hrp->is_active()) {
5705 FreeRegionListIterator iter(&local_cleanup_list);
5706 while (iter.more_available()) {
5707 HeapRegion* hr = iter.get_next();
5708 hrp->cleanup(hr);
5709 }
5710 }
5711
5712 prepend_to_freelist(&local_cleanup_list);
5713 decrement_summary_bytes(cl.bytes_freed());
5714
5715 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5716 cl.humongous_reclaimed());
5717 }
5718
5719 // This routine is similar to the above but does not record
5720 // any policy statistics or update free lists; we are abandoning
5721 // the current incremental collection set in preparation of a
5722 // full collection. After the full GC we will start to build up
5723 // the incremental collection set again.
5724 // This is only called when we're doing a full collection
5725 // and is immediately followed by the tearing down of the young list.
5726
5727 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5728 HeapRegion* cur = cs_head;
5729
5730 while (cur != NULL) {
5731 HeapRegion* next = cur->next_in_collection_set();
5732 assert(cur->in_collection_set(), "bad CS");
5733 cur->set_next_in_collection_set(NULL);
5734 clear_in_cset(cur);
5735 cur->set_young_index_in_cset(-1);
5736 cur = next;
5737 }
5738 }
5739
5740 void G1CollectedHeap::set_free_regions_coming() {
5741 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5742
5743 assert(!free_regions_coming(), "pre-condition");
5744 _free_regions_coming = true;
5745 }
5746
5747 void G1CollectedHeap::reset_free_regions_coming() {
5748 assert(free_regions_coming(), "pre-condition");
5749
5750 {
5751 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5752 _free_regions_coming = false;
5753 SecondaryFreeList_lock->notify_all();
5754 }
5755
5756 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5757 }
5758
5759 void G1CollectedHeap::wait_while_free_regions_coming() {
5760 // Most of the time we won't have to wait, so let's do a quick test
5761 // first before we take the lock.
5762 if (!free_regions_coming()) {
5763 return;
5764 }
5765
5766 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5767
5768 {
5769 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5770 while (free_regions_coming()) {
5771 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5772 }
5773 }
5774
5775 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5776 }
5777
5778 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5779 return _allocator->is_retained_old_region(hr);
5780 }
5781
5782 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5783 _young_list->push_region(hr);
5784 }
5785
5786 class NoYoungRegionsClosure: public HeapRegionClosure {
5787 private:
5788 bool _success;
5789 public:
5790 NoYoungRegionsClosure() : _success(true) { }
5791 bool doHeapRegion(HeapRegion* r) {
5792 if (r->is_young()) {
5793 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5794 p2i(r->bottom()), p2i(r->end()));
5795 _success = false;
5796 }
5797 return false;
5798 }
5799 bool success() { return _success; }
5800 };
5801
5802 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5803 bool ret = _young_list->check_list_empty(check_sample);
5804
5805 if (check_heap) {
5806 NoYoungRegionsClosure closure;
5807 heap_region_iterate(&closure);
5808 ret = ret && closure.success();
5809 }
5810
5811 return ret;
5812 }
5813
5814 class TearDownRegionSetsClosure : public HeapRegionClosure {
5815 private:
5816 HeapRegionSet *_old_set;
5817
5818 public:
5819 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5820
5821 bool doHeapRegion(HeapRegion* r) {
5822 if (r->is_old()) {
5823 _old_set->remove(r);
5824 } else {
5825 // We ignore free regions, we'll empty the free list afterwards.
5826 // We ignore young regions, we'll empty the young list afterwards.
5827 // We ignore humongous regions, we're not tearing down the
5828 // humongous regions set.
5829 assert(r->is_free() || r->is_young() || r->is_humongous(),
5830 "it cannot be another type");
5831 }
5832 return false;
5833 }
5834
5835 ~TearDownRegionSetsClosure() {
5836 assert(_old_set->is_empty(), "post-condition");
5837 }
5838 };
5839
5840 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5841 assert_at_safepoint(true /* should_be_vm_thread */);
5842
5843 if (!free_list_only) {
5844 TearDownRegionSetsClosure cl(&_old_set);
5845 heap_region_iterate(&cl);
5846
5847 // Note that emptying the _young_list is postponed and instead done as
5848 // the first step when rebuilding the regions sets again. The reason for
5849 // this is that during a full GC string deduplication needs to know if
5850 // a collected region was young or old when the full GC was initiated.
5851 }
5852 _hrm.remove_all_free_regions();
5853 }
5854
5855 void G1CollectedHeap::increase_used(size_t bytes) {
5856 _summary_bytes_used += bytes;
5857 }
5858
5859 void G1CollectedHeap::decrease_used(size_t bytes) {
5860 assert(_summary_bytes_used >= bytes,
5861 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5862 _summary_bytes_used, bytes);
5863 _summary_bytes_used -= bytes;
5864 }
5865
5866 void G1CollectedHeap::set_used(size_t bytes) {
5867 _summary_bytes_used = bytes;
5868 }
5869
5870 class RebuildRegionSetsClosure : public HeapRegionClosure {
5871 private:
5872 bool _free_list_only;
5873 HeapRegionSet* _old_set;
5874 HeapRegionManager* _hrm;
5875 size_t _total_used;
5876
5877 public:
5878 RebuildRegionSetsClosure(bool free_list_only,
5879 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5880 _free_list_only(free_list_only),
5881 _old_set(old_set), _hrm(hrm), _total_used(0) {
5882 assert(_hrm->num_free_regions() == 0, "pre-condition");
5883 if (!free_list_only) {
5884 assert(_old_set->is_empty(), "pre-condition");
5885 }
5886 }
5887
5888 bool doHeapRegion(HeapRegion* r) {
5889 if (r->is_empty()) {
5890 // Add free regions to the free list
5891 r->set_free();
5892 r->set_allocation_context(AllocationContext::system());
5893 _hrm->insert_into_free_list(r);
5894 } else if (!_free_list_only) {
5895 assert(!r->is_young(), "we should not come across young regions");
5896
5897 if (r->is_humongous()) {
5898 // We ignore humongous regions. We left the humongous set unchanged.
5899 } else {
5900 // Objects that were compacted would have ended up on regions
5901 // that were previously old or free. Archive regions (which are
5902 // old) will not have been touched.
5903 assert(r->is_free() || r->is_old(), "invariant");
5904 // We now consider them old, so register as such. Leave
5905 // archive regions set that way, however, while still adding
5906 // them to the old set.
5907 if (!r->is_archive()) {
5908 r->set_old();
5909 }
5910 _old_set->add(r);
5911 }
5912 _total_used += r->used();
5913 }
5914
5915 return false;
5916 }
5917
5918 size_t total_used() {
5919 return _total_used;
5920 }
5921 };
5922
5923 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5924 assert_at_safepoint(true /* should_be_vm_thread */);
5925
5926 if (!free_list_only) {
5927 _young_list->empty_list();
5928 }
5929
5930 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5931 heap_region_iterate(&cl);
5932
5933 if (!free_list_only) {
5934 set_used(cl.total_used());
5935 if (_archive_allocator != NULL) {
5936 _archive_allocator->clear_used();
5937 }
5938 }
5939 assert(used_unlocked() == recalculate_used(),
5940 "inconsistent used_unlocked(), "
5941 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5942 used_unlocked(), recalculate_used());
5943 }
5944
5945 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5946 _refine_cte_cl->set_concurrent(concurrent);
5947 }
5948
5949 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5950 HeapRegion* hr = heap_region_containing(p);
5951 return hr->is_in(p);
5952 }
5953
5954 // Methods for the mutator alloc region
5955
5956 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5957 bool force) {
5958 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5959 assert(!force || g1_policy()->can_expand_young_list(),
5960 "if force is true we should be able to expand the young list");
5961 bool young_list_full = g1_policy()->is_young_list_full();
5962 if (force || !young_list_full) {
5963 HeapRegion* new_alloc_region = new_region(word_size,
5964 false /* is_old */,
5965 false /* do_expand */);
5966 if (new_alloc_region != NULL) {
5967 set_region_short_lived_locked(new_alloc_region);
5968 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
5969 check_bitmaps("Mutator Region Allocation", new_alloc_region);
5970 return new_alloc_region;
5971 }
5972 }
5973 return NULL;
5974 }
5975
5976 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5977 size_t allocated_bytes) {
5978 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5979 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5980
5981 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5982 increase_used(allocated_bytes);
5983 _hr_printer.retire(alloc_region);
5984 // We update the eden sizes here, when the region is retired,
5985 // instead of when it's allocated, since this is the point that its
5986 // used space has been recored in _summary_bytes_used.
5987 g1mm()->update_eden_size();
5988 }
5989
5990 // Methods for the GC alloc regions
5991
5992 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5993 uint count,
5994 InCSetState dest) {
5995 assert(FreeList_lock->owned_by_self(), "pre-condition");
5996
5997 if (count < g1_policy()->max_regions(dest)) {
5998 const bool is_survivor = (dest.is_young());
5999 HeapRegion* new_alloc_region = new_region(word_size,
6000 !is_survivor,
6001 true /* do_expand */);
6002 if (new_alloc_region != NULL) {
6003 // We really only need to do this for old regions given that we
6004 // should never scan survivors. But it doesn't hurt to do it
6005 // for survivors too.
6006 new_alloc_region->record_timestamp();
6007 if (is_survivor) {
6008 new_alloc_region->set_survivor();
6009 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6010 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6011 } else {
6012 new_alloc_region->set_old();
6013 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6014 check_bitmaps("Old Region Allocation", new_alloc_region);
6015 }
6016 bool during_im = collector_state()->during_initial_mark_pause();
6017 new_alloc_region->note_start_of_copying(during_im);
6018 return new_alloc_region;
6019 }
6020 }
6021 return NULL;
6022 }
6023
6024 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6025 size_t allocated_bytes,
6026 InCSetState dest) {
6027 bool during_im = collector_state()->during_initial_mark_pause();
6028 alloc_region->note_end_of_copying(during_im);
6029 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6030 if (dest.is_young()) {
6031 young_list()->add_survivor_region(alloc_region);
6032 } else {
6033 _old_set.add(alloc_region);
6034 }
6035 _hr_printer.retire(alloc_region);
6036 }
6037
6038 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6039 bool expanded = false;
6040 uint index = _hrm.find_highest_free(&expanded);
6041
6042 if (index != G1_NO_HRM_INDEX) {
6043 if (expanded) {
6044 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6045 HeapRegion::GrainWords * HeapWordSize);
6046 }
6047 _hrm.allocate_free_regions_starting_at(index, 1);
6048 return region_at(index);
6049 }
6050 return NULL;
6051 }
6052
6053 // Heap region set verification
6054
6055 class VerifyRegionListsClosure : public HeapRegionClosure {
6056 private:
6057 HeapRegionSet* _old_set;
6058 HeapRegionSet* _humongous_set;
6059 HeapRegionManager* _hrm;
6060
6061 public:
6062 HeapRegionSetCount _old_count;
6063 HeapRegionSetCount _humongous_count;
6064 HeapRegionSetCount _free_count;
6065
6066 VerifyRegionListsClosure(HeapRegionSet* old_set,
6067 HeapRegionSet* humongous_set,
6068 HeapRegionManager* hrm) :
6069 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6070 _old_count(), _humongous_count(), _free_count(){ }
6071
6072 bool doHeapRegion(HeapRegion* hr) {
6073 if (hr->is_young()) {
6074 // TODO
6075 } else if (hr->is_humongous()) {
6076 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6077 _humongous_count.increment(1u, hr->capacity());
6078 } else if (hr->is_empty()) {
6079 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6080 _free_count.increment(1u, hr->capacity());
6081 } else if (hr->is_old()) {
6082 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6083 _old_count.increment(1u, hr->capacity());
6084 } else {
6085 // There are no other valid region types. Check for one invalid
6086 // one we can identify: pinned without old or humongous set.
6087 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6088 ShouldNotReachHere();
6089 }
6090 return false;
6091 }
6092
6093 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6094 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6095 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6096 old_set->total_capacity_bytes(), _old_count.capacity());
6097
6098 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6099 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6100 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6101
6102 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6103 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6104 free_list->total_capacity_bytes(), _free_count.capacity());
6105 }
6106 };
6107
6108 void G1CollectedHeap::verify_region_sets() {
6109 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6110
6111 // First, check the explicit lists.
6112 _hrm.verify();
6113 {
6114 // Given that a concurrent operation might be adding regions to
6115 // the secondary free list we have to take the lock before
6116 // verifying it.
6117 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6118 _secondary_free_list.verify_list();
6119 }
6120
6121 // If a concurrent region freeing operation is in progress it will
6122 // be difficult to correctly attributed any free regions we come
6123 // across to the correct free list given that they might belong to
6124 // one of several (free_list, secondary_free_list, any local lists,
6125 // etc.). So, if that's the case we will skip the rest of the
6126 // verification operation. Alternatively, waiting for the concurrent
6127 // operation to complete will have a non-trivial effect on the GC's
6128 // operation (no concurrent operation will last longer than the
6129 // interval between two calls to verification) and it might hide
6130 // any issues that we would like to catch during testing.
6131 if (free_regions_coming()) {
6132 return;
6133 }
6134
6135 // Make sure we append the secondary_free_list on the free_list so
6136 // that all free regions we will come across can be safely
6137 // attributed to the free_list.
6138 append_secondary_free_list_if_not_empty_with_lock();
6139
6140 // Finally, make sure that the region accounting in the lists is
6141 // consistent with what we see in the heap.
6142
6143 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6144 heap_region_iterate(&cl);
6145 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6146 }
6147
6148 // Optimized nmethod scanning
6149
6150 class RegisterNMethodOopClosure: public OopClosure {
6151 G1CollectedHeap* _g1h;
6152 nmethod* _nm;
6153
6154 template <class T> void do_oop_work(T* p) {
6155 T heap_oop = oopDesc::load_heap_oop(p);
6156 if (!oopDesc::is_null(heap_oop)) {
6157 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6158 HeapRegion* hr = _g1h->heap_region_containing(obj);
6159 assert(!hr->is_continues_humongous(),
6160 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6161 " starting at " HR_FORMAT,
6162 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6163
6164 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6165 hr->add_strong_code_root_locked(_nm);
6166 }
6167 }
6168
6169 public:
6170 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6171 _g1h(g1h), _nm(nm) {}
6172
6173 void do_oop(oop* p) { do_oop_work(p); }
6174 void do_oop(narrowOop* p) { do_oop_work(p); }
6175 };
6176
6177 class UnregisterNMethodOopClosure: public OopClosure {
6178 G1CollectedHeap* _g1h;
6179 nmethod* _nm;
6180
6181 template <class T> void do_oop_work(T* p) {
6182 T heap_oop = oopDesc::load_heap_oop(p);
6183 if (!oopDesc::is_null(heap_oop)) {
6184 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6185 HeapRegion* hr = _g1h->heap_region_containing(obj);
6186 assert(!hr->is_continues_humongous(),
6187 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6188 " starting at " HR_FORMAT,
6189 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6190
6191 hr->remove_strong_code_root(_nm);
6192 }
6193 }
6194
6195 public:
6196 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6197 _g1h(g1h), _nm(nm) {}
6198
6199 void do_oop(oop* p) { do_oop_work(p); }
6200 void do_oop(narrowOop* p) { do_oop_work(p); }
6201 };
6202
6203 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6204 CollectedHeap::register_nmethod(nm);
6205
6206 guarantee(nm != NULL, "sanity");
6207 RegisterNMethodOopClosure reg_cl(this, nm);
6208 nm->oops_do(®_cl);
6209 }
6210
6211 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6212 CollectedHeap::unregister_nmethod(nm);
6213
6214 guarantee(nm != NULL, "sanity");
6215 UnregisterNMethodOopClosure reg_cl(this, nm);
6216 nm->oops_do(®_cl, true);
6217 }
6218
6219 void G1CollectedHeap::purge_code_root_memory() {
6220 double purge_start = os::elapsedTime();
6221 G1CodeRootSet::purge();
6222 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6223 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6224 }
6225
6226 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6227 G1CollectedHeap* _g1h;
6228
6229 public:
6230 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6231 _g1h(g1h) {}
6232
6233 void do_code_blob(CodeBlob* cb) {
6234 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6235 if (nm == NULL) {
6236 return;
6237 }
6238
6239 if (ScavengeRootsInCode) {
6240 _g1h->register_nmethod(nm);
6241 }
6242 }
6243 };
6244
6245 void G1CollectedHeap::rebuild_strong_code_roots() {
6246 RebuildStrongCodeRootClosure blob_cl(this);
6247 CodeCache::blobs_do(&blob_cl);
6248 }