1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectorPolicy.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1MarkSweep.hpp"
42 #include "gc/g1/g1OopClosures.inline.hpp"
43 #include "gc/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc/g1/g1RemSet.inline.hpp"
46 #include "gc/g1/g1RootClosures.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcId.hpp"
57 #include "gc/shared/gcLocker.inline.hpp"
58 #include "gc/shared/gcTimer.hpp"
59 #include "gc/shared/gcTrace.hpp"
60 #include "gc/shared/gcTraceTime.inline.hpp"
61 #include "gc/shared/generationSpec.hpp"
62 #include "gc/shared/isGCActiveMark.hpp"
63 #include "gc/shared/referenceProcessor.hpp"
64 #include "gc/shared/taskqueue.inline.hpp"
65 #include "logging/log.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_dirtied;
116 G1CollectedHeap* _g1h;
117 G1SATBCardTableLoggingModRefBS* _g1_bs;
118
119 HeapRegion* region_for_card(jbyte* card_ptr) const {
120 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
121 }
122
123 bool will_become_free(HeapRegion* hr) const {
124 // A region will be freed by free_collection_set if the region is in the
125 // collection set and has not had an evacuation failure.
126 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
127 }
128
129 public:
130 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
131 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
132
133 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
134 HeapRegion* hr = region_for_card(card_ptr);
135
136 // Should only dirty cards in regions that won't be freed.
137 if (!will_become_free(hr)) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_dirtied++;
140 }
141
142 return true;
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
160 {
161 // Claim the right to put the region on the dirty cards region list
162 // by installing a self pointer.
163 HeapRegion* next = hr->get_next_dirty_cards_region();
164 if (next == NULL) {
165 HeapRegion* res = (HeapRegion*)
166 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
167 NULL);
168 if (res == NULL) {
169 HeapRegion* head;
170 do {
171 // Put the region to the dirty cards region list.
172 head = _dirty_cards_region_list;
173 next = (HeapRegion*)
174 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
175 if (next == head) {
176 assert(hr->get_next_dirty_cards_region() == hr,
177 "hr->get_next_dirty_cards_region() != hr");
178 if (next == NULL) {
179 // The last region in the list points to itself.
180 hr->set_next_dirty_cards_region(hr);
181 } else {
182 hr->set_next_dirty_cards_region(next);
183 }
184 }
185 } while (next != head);
186 }
187 }
188 }
189
190 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
191 {
192 HeapRegion* head;
193 HeapRegion* hr;
194 do {
195 head = _dirty_cards_region_list;
196 if (head == NULL) {
197 return NULL;
198 }
199 HeapRegion* new_head = head->get_next_dirty_cards_region();
200 if (head == new_head) {
201 // The last region.
202 new_head = NULL;
203 }
204 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
205 head);
206 } while (hr != head);
207 assert(hr != NULL, "invariant");
208 hr->set_next_dirty_cards_region(NULL);
209 return hr;
210 }
211
212 // Returns true if the reference points to an object that
213 // can move in an incremental collection.
214 bool G1CollectedHeap::is_scavengable(const void* p) {
215 HeapRegion* hr = heap_region_containing(p);
216 return !hr->is_pinned();
217 }
218
219 // Private methods.
220
221 HeapRegion*
222 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
223 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
224 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
225 if (!_secondary_free_list.is_empty()) {
226 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
227 "secondary_free_list has %u entries",
228 _secondary_free_list.length());
229 // It looks as if there are free regions available on the
230 // secondary_free_list. Let's move them to the free_list and try
231 // again to allocate from it.
232 append_secondary_free_list();
233
234 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
235 "empty we should have moved at least one entry to the free_list");
236 HeapRegion* res = _hrm.allocate_free_region(is_old);
237 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
238 "allocated " HR_FORMAT " from secondary_free_list",
239 HR_FORMAT_PARAMS(res));
240 return res;
241 }
242
243 // Wait here until we get notified either when (a) there are no
244 // more free regions coming or (b) some regions have been moved on
245 // the secondary_free_list.
246 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
247 }
248
249 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
250 "could not allocate from secondary_free_list");
251 return NULL;
252 }
253
254 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
255 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
256 "the only time we use this to allocate a humongous region is "
257 "when we are allocating a single humongous region");
258
259 HeapRegion* res;
260 if (G1StressConcRegionFreeing) {
261 if (!_secondary_free_list.is_empty()) {
262 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
263 "forced to look at the secondary_free_list");
264 res = new_region_try_secondary_free_list(is_old);
265 if (res != NULL) {
266 return res;
267 }
268 }
269 }
270
271 res = _hrm.allocate_free_region(is_old);
272
273 if (res == NULL) {
274 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
275 "res == NULL, trying the secondary_free_list");
276 res = new_region_try_secondary_free_list(is_old);
277 }
278 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
279 // Currently, only attempts to allocate GC alloc regions set
280 // do_expand to true. So, we should only reach here during a
281 // safepoint. If this assumption changes we might have to
282 // reconsider the use of _expand_heap_after_alloc_failure.
283 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
284
285 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
286 word_size * HeapWordSize);
287
288 if (expand(word_size * HeapWordSize)) {
289 // Given that expand() succeeded in expanding the heap, and we
290 // always expand the heap by an amount aligned to the heap
291 // region size, the free list should in theory not be empty.
292 // In either case allocate_free_region() will check for NULL.
293 res = _hrm.allocate_free_region(is_old);
294 } else {
295 _expand_heap_after_alloc_failure = false;
296 }
297 }
298 return res;
299 }
300
301 HeapWord*
302 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
303 uint num_regions,
304 size_t word_size,
305 AllocationContext_t context) {
306 assert(first != G1_NO_HRM_INDEX, "pre-condition");
307 assert(is_humongous(word_size), "word_size should be humongous");
308 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
309
310 // Index of last region in the series.
311 uint last = first + num_regions - 1;
312
313 // We need to initialize the region(s) we just discovered. This is
314 // a bit tricky given that it can happen concurrently with
315 // refinement threads refining cards on these regions and
316 // potentially wanting to refine the BOT as they are scanning
317 // those cards (this can happen shortly after a cleanup; see CR
318 // 6991377). So we have to set up the region(s) carefully and in
319 // a specific order.
320
321 // The word size sum of all the regions we will allocate.
322 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
323 assert(word_size <= word_size_sum, "sanity");
324
325 // This will be the "starts humongous" region.
326 HeapRegion* first_hr = region_at(first);
327 // The header of the new object will be placed at the bottom of
328 // the first region.
329 HeapWord* new_obj = first_hr->bottom();
330 // This will be the new top of the new object.
331 HeapWord* obj_top = new_obj + word_size;
332
333 // First, we need to zero the header of the space that we will be
334 // allocating. When we update top further down, some refinement
335 // threads might try to scan the region. By zeroing the header we
336 // ensure that any thread that will try to scan the region will
337 // come across the zero klass word and bail out.
338 //
339 // NOTE: It would not have been correct to have used
340 // CollectedHeap::fill_with_object() and make the space look like
341 // an int array. The thread that is doing the allocation will
342 // later update the object header to a potentially different array
343 // type and, for a very short period of time, the klass and length
344 // fields will be inconsistent. This could cause a refinement
345 // thread to calculate the object size incorrectly.
346 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
347
348 // How many words we use for filler objects.
349 size_t word_fill_size = word_size_sum - word_size;
350
351 // How many words memory we "waste" which cannot hold a filler object.
352 size_t words_not_fillable = 0;
353
354 if (word_fill_size >= min_fill_size()) {
355 fill_with_objects(obj_top, word_fill_size);
356 } else if (word_fill_size > 0) {
357 // We have space to fill, but we cannot fit an object there.
358 words_not_fillable = word_fill_size;
359 word_fill_size = 0;
360 }
361
362 // We will set up the first region as "starts humongous". This
363 // will also update the BOT covering all the regions to reflect
364 // that there is a single object that starts at the bottom of the
365 // first region.
366 first_hr->set_starts_humongous(obj_top, word_fill_size);
367 first_hr->set_allocation_context(context);
368 // Then, if there are any, we will set up the "continues
369 // humongous" regions.
370 HeapRegion* hr = NULL;
371 for (uint i = first + 1; i <= last; ++i) {
372 hr = region_at(i);
373 hr->set_continues_humongous(first_hr);
374 hr->set_allocation_context(context);
375 }
376
377 // Up to this point no concurrent thread would have been able to
378 // do any scanning on any region in this series. All the top
379 // fields still point to bottom, so the intersection between
380 // [bottom,top] and [card_start,card_end] will be empty. Before we
381 // update the top fields, we'll do a storestore to make sure that
382 // no thread sees the update to top before the zeroing of the
383 // object header and the BOT initialization.
384 OrderAccess::storestore();
385
386 // Now, we will update the top fields of the "continues humongous"
387 // regions except the last one.
388 for (uint i = first; i < last; ++i) {
389 hr = region_at(i);
390 hr->set_top(hr->end());
391 }
392
393 hr = region_at(last);
394 // If we cannot fit a filler object, we must set top to the end
395 // of the humongous object, otherwise we cannot iterate the heap
396 // and the BOT will not be complete.
397 hr->set_top(hr->end() - words_not_fillable);
398
399 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
400 "obj_top should be in last region");
401
402 check_bitmaps("Humongous Region Allocation", first_hr);
403
404 assert(words_not_fillable == 0 ||
405 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
406 "Miscalculation in humongous allocation");
407
408 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
409
410 for (uint i = first; i <= last; ++i) {
411 hr = region_at(i);
412 _humongous_set.add(hr);
413 _hr_printer.alloc(hr);
414 }
415
416 return new_obj;
417 }
418
419 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
420 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
421 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
422 }
423
424 // If could fit into free regions w/o expansion, try.
425 // Otherwise, if can expand, do so.
426 // Otherwise, if using ex regions might help, try with ex given back.
427 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
428 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
429
430 verify_region_sets_optional();
431
432 uint first = G1_NO_HRM_INDEX;
433 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
434
435 if (obj_regions == 1) {
436 // Only one region to allocate, try to use a fast path by directly allocating
437 // from the free lists. Do not try to expand here, we will potentially do that
438 // later.
439 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
440 if (hr != NULL) {
441 first = hr->hrm_index();
442 }
443 } else {
444 // We can't allocate humongous regions spanning more than one region while
445 // cleanupComplete() is running, since some of the regions we find to be
446 // empty might not yet be added to the free list. It is not straightforward
447 // to know in which list they are on so that we can remove them. We only
448 // need to do this if we need to allocate more than one region to satisfy the
449 // current humongous allocation request. If we are only allocating one region
450 // we use the one-region region allocation code (see above), that already
451 // potentially waits for regions from the secondary free list.
452 wait_while_free_regions_coming();
453 append_secondary_free_list_if_not_empty_with_lock();
454
455 // Policy: Try only empty regions (i.e. already committed first). Maybe we
456 // are lucky enough to find some.
457 first = _hrm.find_contiguous_only_empty(obj_regions);
458 if (first != G1_NO_HRM_INDEX) {
459 _hrm.allocate_free_regions_starting_at(first, obj_regions);
460 }
461 }
462
463 if (first == G1_NO_HRM_INDEX) {
464 // Policy: We could not find enough regions for the humongous object in the
465 // free list. Look through the heap to find a mix of free and uncommitted regions.
466 // If so, try expansion.
467 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
468 if (first != G1_NO_HRM_INDEX) {
469 // We found something. Make sure these regions are committed, i.e. expand
470 // the heap. Alternatively we could do a defragmentation GC.
471 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
472 word_size * HeapWordSize);
473
474
475 _hrm.expand_at(first, obj_regions);
476 g1_policy()->record_new_heap_size(num_regions());
477
478 #ifdef ASSERT
479 for (uint i = first; i < first + obj_regions; ++i) {
480 HeapRegion* hr = region_at(i);
481 assert(hr->is_free(), "sanity");
482 assert(hr->is_empty(), "sanity");
483 assert(is_on_master_free_list(hr), "sanity");
484 }
485 #endif
486 _hrm.allocate_free_regions_starting_at(first, obj_regions);
487 } else {
488 // Policy: Potentially trigger a defragmentation GC.
489 }
490 }
491
492 HeapWord* result = NULL;
493 if (first != G1_NO_HRM_INDEX) {
494 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
495 word_size, context);
496 assert(result != NULL, "it should always return a valid result");
497
498 // A successful humongous object allocation changes the used space
499 // information of the old generation so we need to recalculate the
500 // sizes and update the jstat counters here.
501 g1mm()->update_sizes();
502 }
503
504 verify_region_sets_optional();
505
506 return result;
507 }
508
509 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
510 assert_heap_not_locked_and_not_at_safepoint();
511 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
512
513 uint dummy_gc_count_before;
514 uint dummy_gclocker_retry_count = 0;
515 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
516 }
517
518 HeapWord*
519 G1CollectedHeap::mem_allocate(size_t word_size,
520 bool* gc_overhead_limit_was_exceeded) {
521 assert_heap_not_locked_and_not_at_safepoint();
522
523 // Loop until the allocation is satisfied, or unsatisfied after GC.
524 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
525 uint gc_count_before;
526
527 HeapWord* result = NULL;
528 if (!is_humongous(word_size)) {
529 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
530 } else {
531 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
532 }
533 if (result != NULL) {
534 return result;
535 }
536
537 // Create the garbage collection operation...
538 VM_G1CollectForAllocation op(gc_count_before, word_size);
539 op.set_allocation_context(AllocationContext::current());
540
541 // ...and get the VM thread to execute it.
542 VMThread::execute(&op);
543
544 if (op.prologue_succeeded() && op.pause_succeeded()) {
545 // If the operation was successful we'll return the result even
546 // if it is NULL. If the allocation attempt failed immediately
547 // after a Full GC, it's unlikely we'll be able to allocate now.
548 HeapWord* result = op.result();
549 if (result != NULL && !is_humongous(word_size)) {
550 // Allocations that take place on VM operations do not do any
551 // card dirtying and we have to do it here. We only have to do
552 // this for non-humongous allocations, though.
553 dirty_young_block(result, word_size);
554 }
555 return result;
556 } else {
557 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
558 return NULL;
559 }
560 assert(op.result() == NULL,
561 "the result should be NULL if the VM op did not succeed");
562 }
563
564 // Give a warning if we seem to be looping forever.
565 if ((QueuedAllocationWarningCount > 0) &&
566 (try_count % QueuedAllocationWarningCount == 0)) {
567 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
568 }
569 }
570
571 ShouldNotReachHere();
572 return NULL;
573 }
574
575 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
576 AllocationContext_t context,
577 uint* gc_count_before_ret,
578 uint* gclocker_retry_count_ret) {
579 // Make sure you read the note in attempt_allocation_humongous().
580
581 assert_heap_not_locked_and_not_at_safepoint();
582 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
583 "be called for humongous allocation requests");
584
585 // We should only get here after the first-level allocation attempt
586 // (attempt_allocation()) failed to allocate.
587
588 // We will loop until a) we manage to successfully perform the
589 // allocation or b) we successfully schedule a collection which
590 // fails to perform the allocation. b) is the only case when we'll
591 // return NULL.
592 HeapWord* result = NULL;
593 for (int try_count = 1; /* we'll return */; try_count += 1) {
594 bool should_try_gc;
595 uint gc_count_before;
596
597 {
598 MutexLockerEx x(Heap_lock);
599 result = _allocator->attempt_allocation_locked(word_size, context);
600 if (result != NULL) {
601 return result;
602 }
603
604 if (GC_locker::is_active_and_needs_gc()) {
605 if (g1_policy()->can_expand_young_list()) {
606 // No need for an ergo verbose message here,
607 // can_expand_young_list() does this when it returns true.
608 result = _allocator->attempt_allocation_force(word_size, context);
609 if (result != NULL) {
610 return result;
611 }
612 }
613 should_try_gc = false;
614 } else {
615 // The GCLocker may not be active but the GCLocker initiated
616 // GC may not yet have been performed (GCLocker::needs_gc()
617 // returns true). In this case we do not try this GC and
618 // wait until the GCLocker initiated GC is performed, and
619 // then retry the allocation.
620 if (GC_locker::needs_gc()) {
621 should_try_gc = false;
622 } else {
623 // Read the GC count while still holding the Heap_lock.
624 gc_count_before = total_collections();
625 should_try_gc = true;
626 }
627 }
628 }
629
630 if (should_try_gc) {
631 bool succeeded;
632 result = do_collection_pause(word_size, gc_count_before, &succeeded,
633 GCCause::_g1_inc_collection_pause);
634 if (result != NULL) {
635 assert(succeeded, "only way to get back a non-NULL result");
636 return result;
637 }
638
639 if (succeeded) {
640 // If we get here we successfully scheduled a collection which
641 // failed to allocate. No point in trying to allocate
642 // further. We'll just return NULL.
643 MutexLockerEx x(Heap_lock);
644 *gc_count_before_ret = total_collections();
645 return NULL;
646 }
647 } else {
648 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
649 MutexLockerEx x(Heap_lock);
650 *gc_count_before_ret = total_collections();
651 return NULL;
652 }
653 // The GCLocker is either active or the GCLocker initiated
654 // GC has not yet been performed. Stall until it is and
655 // then retry the allocation.
656 GC_locker::stall_until_clear();
657 (*gclocker_retry_count_ret) += 1;
658 }
659
660 // We can reach here if we were unsuccessful in scheduling a
661 // collection (because another thread beat us to it) or if we were
662 // stalled due to the GC locker. In either can we should retry the
663 // allocation attempt in case another thread successfully
664 // performed a collection and reclaimed enough space. We do the
665 // first attempt (without holding the Heap_lock) here and the
666 // follow-on attempt will be at the start of the next loop
667 // iteration (after taking the Heap_lock).
668 result = _allocator->attempt_allocation(word_size, context);
669 if (result != NULL) {
670 return result;
671 }
672
673 // Give a warning if we seem to be looping forever.
674 if ((QueuedAllocationWarningCount > 0) &&
675 (try_count % QueuedAllocationWarningCount == 0)) {
676 warning("G1CollectedHeap::attempt_allocation_slow() "
677 "retries %d times", try_count);
678 }
679 }
680
681 ShouldNotReachHere();
682 return NULL;
683 }
684
685 void G1CollectedHeap::begin_archive_alloc_range() {
686 assert_at_safepoint(true /* should_be_vm_thread */);
687 if (_archive_allocator == NULL) {
688 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
689 }
690 }
691
692 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
693 // Allocations in archive regions cannot be of a size that would be considered
694 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
695 // may be different at archive-restore time.
696 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
697 }
698
699 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
700 assert_at_safepoint(true /* should_be_vm_thread */);
701 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
702 if (is_archive_alloc_too_large(word_size)) {
703 return NULL;
704 }
705 return _archive_allocator->archive_mem_allocate(word_size);
706 }
707
708 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
709 size_t end_alignment_in_bytes) {
710 assert_at_safepoint(true /* should_be_vm_thread */);
711 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
712
713 // Call complete_archive to do the real work, filling in the MemRegion
714 // array with the archive regions.
715 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
716 delete _archive_allocator;
717 _archive_allocator = NULL;
718 }
719
720 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
721 assert(ranges != NULL, "MemRegion array NULL");
722 assert(count != 0, "No MemRegions provided");
723 MemRegion reserved = _hrm.reserved();
724 for (size_t i = 0; i < count; i++) {
725 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
726 return false;
727 }
728 }
729 return true;
730 }
731
732 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
733 assert(!is_init_completed(), "Expect to be called at JVM init time");
734 assert(ranges != NULL, "MemRegion array NULL");
735 assert(count != 0, "No MemRegions provided");
736 MutexLockerEx x(Heap_lock);
737
738 MemRegion reserved = _hrm.reserved();
739 HeapWord* prev_last_addr = NULL;
740 HeapRegion* prev_last_region = NULL;
741
742 // Temporarily disable pretouching of heap pages. This interface is used
743 // when mmap'ing archived heap data in, so pre-touching is wasted.
744 FlagSetting fs(AlwaysPreTouch, false);
745
746 // Enable archive object checking in G1MarkSweep. We have to let it know
747 // about each archive range, so that objects in those ranges aren't marked.
748 G1MarkSweep::enable_archive_object_check();
749
750 // For each specified MemRegion range, allocate the corresponding G1
751 // regions and mark them as archive regions. We expect the ranges in
752 // ascending starting address order, without overlap.
753 for (size_t i = 0; i < count; i++) {
754 MemRegion curr_range = ranges[i];
755 HeapWord* start_address = curr_range.start();
756 size_t word_size = curr_range.word_size();
757 HeapWord* last_address = curr_range.last();
758 size_t commits = 0;
759
760 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
761 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
762 p2i(start_address), p2i(last_address));
763 guarantee(start_address > prev_last_addr,
764 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
765 p2i(start_address), p2i(prev_last_addr));
766 prev_last_addr = last_address;
767
768 // Check for ranges that start in the same G1 region in which the previous
769 // range ended, and adjust the start address so we don't try to allocate
770 // the same region again. If the current range is entirely within that
771 // region, skip it, just adjusting the recorded top.
772 HeapRegion* start_region = _hrm.addr_to_region(start_address);
773 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
774 start_address = start_region->end();
775 if (start_address > last_address) {
776 increase_used(word_size * HeapWordSize);
777 start_region->set_top(last_address + 1);
778 continue;
779 }
780 start_region->set_top(start_address);
781 curr_range = MemRegion(start_address, last_address + 1);
782 start_region = _hrm.addr_to_region(start_address);
783 }
784
785 // Perform the actual region allocation, exiting if it fails.
786 // Then note how much new space we have allocated.
787 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
788 return false;
789 }
790 increase_used(word_size * HeapWordSize);
791 if (commits != 0) {
792 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
793 HeapRegion::GrainWords * HeapWordSize * commits);
794
795 }
796
797 // Mark each G1 region touched by the range as archive, add it to the old set,
798 // and set the allocation context and top.
799 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
800 HeapRegion* last_region = _hrm.addr_to_region(last_address);
801 prev_last_region = last_region;
802
803 while (curr_region != NULL) {
804 assert(curr_region->is_empty() && !curr_region->is_pinned(),
805 "Region already in use (index %u)", curr_region->hrm_index());
806 curr_region->set_allocation_context(AllocationContext::system());
807 curr_region->set_archive();
808 _hr_printer.alloc(curr_region);
809 _old_set.add(curr_region);
810 if (curr_region != last_region) {
811 curr_region->set_top(curr_region->end());
812 curr_region = _hrm.next_region_in_heap(curr_region);
813 } else {
814 curr_region->set_top(last_address + 1);
815 curr_region = NULL;
816 }
817 }
818
819 // Notify mark-sweep of the archive range.
820 G1MarkSweep::set_range_archive(curr_range, true);
821 }
822 return true;
823 }
824
825 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
826 assert(!is_init_completed(), "Expect to be called at JVM init time");
827 assert(ranges != NULL, "MemRegion array NULL");
828 assert(count != 0, "No MemRegions provided");
829 MemRegion reserved = _hrm.reserved();
830 HeapWord *prev_last_addr = NULL;
831 HeapRegion* prev_last_region = NULL;
832
833 // For each MemRegion, create filler objects, if needed, in the G1 regions
834 // that contain the address range. The address range actually within the
835 // MemRegion will not be modified. That is assumed to have been initialized
836 // elsewhere, probably via an mmap of archived heap data.
837 MutexLockerEx x(Heap_lock);
838 for (size_t i = 0; i < count; i++) {
839 HeapWord* start_address = ranges[i].start();
840 HeapWord* last_address = ranges[i].last();
841
842 assert(reserved.contains(start_address) && reserved.contains(last_address),
843 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
844 p2i(start_address), p2i(last_address));
845 assert(start_address > prev_last_addr,
846 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
847 p2i(start_address), p2i(prev_last_addr));
848
849 HeapRegion* start_region = _hrm.addr_to_region(start_address);
850 HeapRegion* last_region = _hrm.addr_to_region(last_address);
851 HeapWord* bottom_address = start_region->bottom();
852
853 // Check for a range beginning in the same region in which the
854 // previous one ended.
855 if (start_region == prev_last_region) {
856 bottom_address = prev_last_addr + 1;
857 }
858
859 // Verify that the regions were all marked as archive regions by
860 // alloc_archive_regions.
861 HeapRegion* curr_region = start_region;
862 while (curr_region != NULL) {
863 guarantee(curr_region->is_archive(),
864 "Expected archive region at index %u", curr_region->hrm_index());
865 if (curr_region != last_region) {
866 curr_region = _hrm.next_region_in_heap(curr_region);
867 } else {
868 curr_region = NULL;
869 }
870 }
871
872 prev_last_addr = last_address;
873 prev_last_region = last_region;
874
875 // Fill the memory below the allocated range with dummy object(s),
876 // if the region bottom does not match the range start, or if the previous
877 // range ended within the same G1 region, and there is a gap.
878 if (start_address != bottom_address) {
879 size_t fill_size = pointer_delta(start_address, bottom_address);
880 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
881 increase_used(fill_size * HeapWordSize);
882 }
883 }
884 }
885
886 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
887 uint* gc_count_before_ret,
888 uint* gclocker_retry_count_ret) {
889 assert_heap_not_locked_and_not_at_safepoint();
890 assert(!is_humongous(word_size), "attempt_allocation() should not "
891 "be called for humongous allocation requests");
892
893 AllocationContext_t context = AllocationContext::current();
894 HeapWord* result = _allocator->attempt_allocation(word_size, context);
895
896 if (result == NULL) {
897 result = attempt_allocation_slow(word_size,
898 context,
899 gc_count_before_ret,
900 gclocker_retry_count_ret);
901 }
902 assert_heap_not_locked();
903 if (result != NULL) {
904 dirty_young_block(result, word_size);
905 }
906 return result;
907 }
908
909 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
910 assert(!is_init_completed(), "Expect to be called at JVM init time");
911 assert(ranges != NULL, "MemRegion array NULL");
912 assert(count != 0, "No MemRegions provided");
913 MemRegion reserved = _hrm.reserved();
914 HeapWord* prev_last_addr = NULL;
915 HeapRegion* prev_last_region = NULL;
916 size_t size_used = 0;
917 size_t uncommitted_regions = 0;
918
919 // For each Memregion, free the G1 regions that constitute it, and
920 // notify mark-sweep that the range is no longer to be considered 'archive.'
921 MutexLockerEx x(Heap_lock);
922 for (size_t i = 0; i < count; i++) {
923 HeapWord* start_address = ranges[i].start();
924 HeapWord* last_address = ranges[i].last();
925
926 assert(reserved.contains(start_address) && reserved.contains(last_address),
927 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
928 p2i(start_address), p2i(last_address));
929 assert(start_address > prev_last_addr,
930 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
931 p2i(start_address), p2i(prev_last_addr));
932 size_used += ranges[i].byte_size();
933 prev_last_addr = last_address;
934
935 HeapRegion* start_region = _hrm.addr_to_region(start_address);
936 HeapRegion* last_region = _hrm.addr_to_region(last_address);
937
938 // Check for ranges that start in the same G1 region in which the previous
939 // range ended, and adjust the start address so we don't try to free
940 // the same region again. If the current range is entirely within that
941 // region, skip it.
942 if (start_region == prev_last_region) {
943 start_address = start_region->end();
944 if (start_address > last_address) {
945 continue;
946 }
947 start_region = _hrm.addr_to_region(start_address);
948 }
949 prev_last_region = last_region;
950
951 // After verifying that each region was marked as an archive region by
952 // alloc_archive_regions, set it free and empty and uncommit it.
953 HeapRegion* curr_region = start_region;
954 while (curr_region != NULL) {
955 guarantee(curr_region->is_archive(),
956 "Expected archive region at index %u", curr_region->hrm_index());
957 uint curr_index = curr_region->hrm_index();
958 _old_set.remove(curr_region);
959 curr_region->set_free();
960 curr_region->set_top(curr_region->bottom());
961 if (curr_region != last_region) {
962 curr_region = _hrm.next_region_in_heap(curr_region);
963 } else {
964 curr_region = NULL;
965 }
966 _hrm.shrink_at(curr_index, 1);
967 uncommitted_regions++;
968 }
969
970 // Notify mark-sweep that this is no longer an archive range.
971 G1MarkSweep::set_range_archive(ranges[i], false);
972 }
973
974 if (uncommitted_regions != 0) {
975 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
976 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
977 }
978 decrease_used(size_used);
979 }
980
981 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
982 uint* gc_count_before_ret,
983 uint* gclocker_retry_count_ret) {
984 // The structure of this method has a lot of similarities to
985 // attempt_allocation_slow(). The reason these two were not merged
986 // into a single one is that such a method would require several "if
987 // allocation is not humongous do this, otherwise do that"
988 // conditional paths which would obscure its flow. In fact, an early
989 // version of this code did use a unified method which was harder to
990 // follow and, as a result, it had subtle bugs that were hard to
991 // track down. So keeping these two methods separate allows each to
992 // be more readable. It will be good to keep these two in sync as
993 // much as possible.
994
995 assert_heap_not_locked_and_not_at_safepoint();
996 assert(is_humongous(word_size), "attempt_allocation_humongous() "
997 "should only be called for humongous allocations");
998
999 // Humongous objects can exhaust the heap quickly, so we should check if we
1000 // need to start a marking cycle at each humongous object allocation. We do
1001 // the check before we do the actual allocation. The reason for doing it
1002 // before the allocation is that we avoid having to keep track of the newly
1003 // allocated memory while we do a GC.
1004 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1005 word_size)) {
1006 collect(GCCause::_g1_humongous_allocation);
1007 }
1008
1009 // We will loop until a) we manage to successfully perform the
1010 // allocation or b) we successfully schedule a collection which
1011 // fails to perform the allocation. b) is the only case when we'll
1012 // return NULL.
1013 HeapWord* result = NULL;
1014 for (int try_count = 1; /* we'll return */; try_count += 1) {
1015 bool should_try_gc;
1016 uint gc_count_before;
1017
1018 {
1019 MutexLockerEx x(Heap_lock);
1020
1021 // Given that humongous objects are not allocated in young
1022 // regions, we'll first try to do the allocation without doing a
1023 // collection hoping that there's enough space in the heap.
1024 result = humongous_obj_allocate(word_size, AllocationContext::current());
1025 if (result != NULL) {
1026 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1027 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1028 return result;
1029 }
1030
1031 if (GC_locker::is_active_and_needs_gc()) {
1032 should_try_gc = false;
1033 } else {
1034 // The GCLocker may not be active but the GCLocker initiated
1035 // GC may not yet have been performed (GCLocker::needs_gc()
1036 // returns true). In this case we do not try this GC and
1037 // wait until the GCLocker initiated GC is performed, and
1038 // then retry the allocation.
1039 if (GC_locker::needs_gc()) {
1040 should_try_gc = false;
1041 } else {
1042 // Read the GC count while still holding the Heap_lock.
1043 gc_count_before = total_collections();
1044 should_try_gc = true;
1045 }
1046 }
1047 }
1048
1049 if (should_try_gc) {
1050 // If we failed to allocate the humongous object, we should try to
1051 // do a collection pause (if we're allowed) in case it reclaims
1052 // enough space for the allocation to succeed after the pause.
1053
1054 bool succeeded;
1055 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1056 GCCause::_g1_humongous_allocation);
1057 if (result != NULL) {
1058 assert(succeeded, "only way to get back a non-NULL result");
1059 return result;
1060 }
1061
1062 if (succeeded) {
1063 // If we get here we successfully scheduled a collection which
1064 // failed to allocate. No point in trying to allocate
1065 // further. We'll just return NULL.
1066 MutexLockerEx x(Heap_lock);
1067 *gc_count_before_ret = total_collections();
1068 return NULL;
1069 }
1070 } else {
1071 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1072 MutexLockerEx x(Heap_lock);
1073 *gc_count_before_ret = total_collections();
1074 return NULL;
1075 }
1076 // The GCLocker is either active or the GCLocker initiated
1077 // GC has not yet been performed. Stall until it is and
1078 // then retry the allocation.
1079 GC_locker::stall_until_clear();
1080 (*gclocker_retry_count_ret) += 1;
1081 }
1082
1083 // We can reach here if we were unsuccessful in scheduling a
1084 // collection (because another thread beat us to it) or if we were
1085 // stalled due to the GC locker. In either can we should retry the
1086 // allocation attempt in case another thread successfully
1087 // performed a collection and reclaimed enough space. Give a
1088 // warning if we seem to be looping forever.
1089
1090 if ((QueuedAllocationWarningCount > 0) &&
1091 (try_count % QueuedAllocationWarningCount == 0)) {
1092 warning("G1CollectedHeap::attempt_allocation_humongous() "
1093 "retries %d times", try_count);
1094 }
1095 }
1096
1097 ShouldNotReachHere();
1098 return NULL;
1099 }
1100
1101 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1102 AllocationContext_t context,
1103 bool expect_null_mutator_alloc_region) {
1104 assert_at_safepoint(true /* should_be_vm_thread */);
1105 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1106 "the current alloc region was unexpectedly found to be non-NULL");
1107
1108 if (!is_humongous(word_size)) {
1109 return _allocator->attempt_allocation_locked(word_size, context);
1110 } else {
1111 HeapWord* result = humongous_obj_allocate(word_size, context);
1112 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1113 collector_state()->set_initiate_conc_mark_if_possible(true);
1114 }
1115 return result;
1116 }
1117
1118 ShouldNotReachHere();
1119 }
1120
1121 class PostMCRemSetClearClosure: public HeapRegionClosure {
1122 G1CollectedHeap* _g1h;
1123 ModRefBarrierSet* _mr_bs;
1124 public:
1125 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1126 _g1h(g1h), _mr_bs(mr_bs) {}
1127
1128 bool doHeapRegion(HeapRegion* r) {
1129 HeapRegionRemSet* hrrs = r->rem_set();
1130
1131 _g1h->reset_gc_time_stamps(r);
1132
1133 if (r->is_continues_humongous()) {
1134 // We'll assert that the strong code root list and RSet is empty
1135 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1136 assert(hrrs->occupied() == 0, "RSet should be empty");
1137 } else {
1138 hrrs->clear();
1139 }
1140 // You might think here that we could clear just the cards
1141 // corresponding to the used region. But no: if we leave a dirty card
1142 // in a region we might allocate into, then it would prevent that card
1143 // from being enqueued, and cause it to be missed.
1144 // Re: the performance cost: we shouldn't be doing full GC anyway!
1145 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1146
1147 return false;
1148 }
1149 };
1150
1151 void G1CollectedHeap::clear_rsets_post_compaction() {
1152 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1153 heap_region_iterate(&rs_clear);
1154 }
1155
1156 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1157 G1CollectedHeap* _g1h;
1158 UpdateRSOopClosure _cl;
1159 public:
1160 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1161 _cl(g1->g1_rem_set(), worker_i),
1162 _g1h(g1)
1163 { }
1164
1165 bool doHeapRegion(HeapRegion* r) {
1166 if (!r->is_continues_humongous()) {
1167 _cl.set_from(r);
1168 r->oop_iterate(&_cl);
1169 }
1170 return false;
1171 }
1172 };
1173
1174 class ParRebuildRSTask: public AbstractGangTask {
1175 G1CollectedHeap* _g1;
1176 HeapRegionClaimer _hrclaimer;
1177
1178 public:
1179 ParRebuildRSTask(G1CollectedHeap* g1) :
1180 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1181
1182 void work(uint worker_id) {
1183 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1184 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1185 }
1186 };
1187
1188 class PostCompactionPrinterClosure: public HeapRegionClosure {
1189 private:
1190 G1HRPrinter* _hr_printer;
1191 public:
1192 bool doHeapRegion(HeapRegion* hr) {
1193 assert(!hr->is_young(), "not expecting to find young regions");
1194 _hr_printer->post_compaction(hr);
1195 return false;
1196 }
1197
1198 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1199 : _hr_printer(hr_printer) { }
1200 };
1201
1202 void G1CollectedHeap::print_hrm_post_compaction() {
1203 if (_hr_printer.is_active()) {
1204 PostCompactionPrinterClosure cl(hr_printer());
1205 heap_region_iterate(&cl);
1206 }
1207
1208 }
1209
1210 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1211 bool clear_all_soft_refs) {
1212 assert_at_safepoint(true /* should_be_vm_thread */);
1213
1214 if (GC_locker::check_active_before_gc()) {
1215 return false;
1216 }
1217
1218 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1219 gc_timer->register_gc_start();
1220
1221 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1222 GCIdMark gc_id_mark;
1223 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1224
1225 SvcGCMarker sgcm(SvcGCMarker::FULL);
1226 ResourceMark rm;
1227
1228 print_heap_before_gc();
1229 trace_heap_before_gc(gc_tracer);
1230
1231 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1232
1233 verify_region_sets_optional();
1234
1235 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1236 collector_policy()->should_clear_all_soft_refs();
1237
1238 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1239
1240 {
1241 IsGCActiveMark x;
1242
1243 // Timing
1244 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1245 GCTraceCPUTime tcpu;
1246
1247 {
1248 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1249 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1250 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1251
1252 g1_policy()->record_full_collection_start();
1253
1254 // Note: When we have a more flexible GC logging framework that
1255 // allows us to add optional attributes to a GC log record we
1256 // could consider timing and reporting how long we wait in the
1257 // following two methods.
1258 wait_while_free_regions_coming();
1259 // If we start the compaction before the CM threads finish
1260 // scanning the root regions we might trip them over as we'll
1261 // be moving objects / updating references. So let's wait until
1262 // they are done. By telling them to abort, they should complete
1263 // early.
1264 _cm->root_regions()->abort();
1265 _cm->root_regions()->wait_until_scan_finished();
1266 append_secondary_free_list_if_not_empty_with_lock();
1267
1268 gc_prologue(true);
1269 increment_total_collections(true /* full gc */);
1270 increment_old_marking_cycles_started();
1271
1272 assert(used() == recalculate_used(), "Should be equal");
1273
1274 verify_before_gc();
1275
1276 check_bitmaps("Full GC Start");
1277 pre_full_gc_dump(gc_timer);
1278
1279 #if defined(COMPILER2) || INCLUDE_JVMCI
1280 DerivedPointerTable::clear();
1281 #endif
1282
1283 // Disable discovery and empty the discovered lists
1284 // for the CM ref processor.
1285 ref_processor_cm()->disable_discovery();
1286 ref_processor_cm()->abandon_partial_discovery();
1287 ref_processor_cm()->verify_no_references_recorded();
1288
1289 // Abandon current iterations of concurrent marking and concurrent
1290 // refinement, if any are in progress. We have to do this before
1291 // wait_until_scan_finished() below.
1292 concurrent_mark()->abort();
1293
1294 // Make sure we'll choose a new allocation region afterwards.
1295 _allocator->release_mutator_alloc_region();
1296 _allocator->abandon_gc_alloc_regions();
1297 g1_rem_set()->cleanupHRRS();
1298
1299 // We may have added regions to the current incremental collection
1300 // set between the last GC or pause and now. We need to clear the
1301 // incremental collection set and then start rebuilding it afresh
1302 // after this full GC.
1303 abandon_collection_set(g1_policy()->inc_cset_head());
1304 g1_policy()->clear_incremental_cset();
1305 g1_policy()->stop_incremental_cset_building();
1306
1307 tear_down_region_sets(false /* free_list_only */);
1308 collector_state()->set_gcs_are_young(true);
1309
1310 // See the comments in g1CollectedHeap.hpp and
1311 // G1CollectedHeap::ref_processing_init() about
1312 // how reference processing currently works in G1.
1313
1314 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1315 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1316
1317 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1318 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1319
1320 ref_processor_stw()->enable_discovery();
1321 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1322
1323 // Do collection work
1324 {
1325 HandleMark hm; // Discard invalid handles created during gc
1326 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1327 }
1328
1329 assert(num_free_regions() == 0, "we should not have added any free regions");
1330 rebuild_region_sets(false /* free_list_only */);
1331
1332 // Enqueue any discovered reference objects that have
1333 // not been removed from the discovered lists.
1334 ref_processor_stw()->enqueue_discovered_references();
1335
1336 #if defined(COMPILER2) || INCLUDE_JVMCI
1337 DerivedPointerTable::update_pointers();
1338 #endif
1339
1340 MemoryService::track_memory_usage();
1341
1342 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1343 ref_processor_stw()->verify_no_references_recorded();
1344
1345 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1346 ClassLoaderDataGraph::purge();
1347 MetaspaceAux::verify_metrics();
1348
1349 // Note: since we've just done a full GC, concurrent
1350 // marking is no longer active. Therefore we need not
1351 // re-enable reference discovery for the CM ref processor.
1352 // That will be done at the start of the next marking cycle.
1353 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 reset_gc_time_stamp();
1357 // Since everything potentially moved, we will clear all remembered
1358 // sets, and clear all cards. Later we will rebuild remembered
1359 // sets. We will also reset the GC time stamps of the regions.
1360 clear_rsets_post_compaction();
1361 check_gc_time_stamps();
1362
1363 resize_if_necessary_after_full_collection();
1364
1365 // We should do this after we potentially resize the heap so
1366 // that all the COMMIT / UNCOMMIT events are generated before
1367 // the compaction events.
1368 print_hrm_post_compaction();
1369
1370 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1371 if (hot_card_cache->use_cache()) {
1372 hot_card_cache->reset_card_counts();
1373 hot_card_cache->reset_hot_cache();
1374 }
1375
1376 // Rebuild remembered sets of all regions.
1377 uint n_workers =
1378 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1379 workers()->active_workers(),
1380 Threads::number_of_non_daemon_threads());
1381 workers()->set_active_workers(n_workers);
1382
1383 ParRebuildRSTask rebuild_rs_task(this);
1384 workers()->run_task(&rebuild_rs_task);
1385
1386 // Rebuild the strong code root lists for each region
1387 rebuild_strong_code_roots();
1388
1389 if (true) { // FIXME
1390 MetaspaceGC::compute_new_size();
1391 }
1392
1393 #ifdef TRACESPINNING
1394 ParallelTaskTerminator::print_termination_counts();
1395 #endif
1396
1397 // Discard all rset updates
1398 JavaThread::dirty_card_queue_set().abandon_logs();
1399 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1400
1401 _young_list->reset_sampled_info();
1402 // At this point there should be no regions in the
1403 // entire heap tagged as young.
1404 assert(check_young_list_empty(true /* check_heap */),
1405 "young list should be empty at this point");
1406
1407 // Update the number of full collections that have been completed.
1408 increment_old_marking_cycles_completed(false /* concurrent */);
1409
1410 _hrm.verify_optional();
1411 verify_region_sets_optional();
1412
1413 verify_after_gc();
1414
1415 // Clear the previous marking bitmap, if needed for bitmap verification.
1416 // Note we cannot do this when we clear the next marking bitmap in
1417 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1418 // objects marked during a full GC against the previous bitmap.
1419 // But we need to clear it before calling check_bitmaps below since
1420 // the full GC has compacted objects and updated TAMS but not updated
1421 // the prev bitmap.
1422 if (G1VerifyBitmaps) {
1423 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1424 }
1425 check_bitmaps("Full GC End");
1426
1427 // Start a new incremental collection set for the next pause
1428 assert(g1_policy()->collection_set() == NULL, "must be");
1429 g1_policy()->start_incremental_cset_building();
1430
1431 clear_cset_fast_test();
1432
1433 _allocator->init_mutator_alloc_region();
1434
1435 g1_policy()->record_full_collection_end();
1436
1437 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1438 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1439 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1440 // before any GC notifications are raised.
1441 g1mm()->update_sizes();
1442
1443 gc_epilogue(true);
1444 }
1445
1446 g1_policy()->print_detailed_heap_transition();
1447
1448 print_heap_after_gc();
1449 trace_heap_after_gc(gc_tracer);
1450
1451 post_full_gc_dump(gc_timer);
1452
1453 gc_timer->register_gc_end();
1454 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1455 }
1456
1457 return true;
1458 }
1459
1460 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1461 // Currently, there is no facility in the do_full_collection(bool) API to notify
1462 // the caller that the collection did not succeed (e.g., because it was locked
1463 // out by the GC locker). So, right now, we'll ignore the return value.
1464 bool dummy = do_full_collection(true, /* explicit_gc */
1465 clear_all_soft_refs);
1466 }
1467
1468 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1469 // Include bytes that will be pre-allocated to support collections, as "used".
1470 const size_t used_after_gc = used();
1471 const size_t capacity_after_gc = capacity();
1472 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1473
1474 // This is enforced in arguments.cpp.
1475 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1476 "otherwise the code below doesn't make sense");
1477
1478 // We don't have floating point command-line arguments
1479 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1480 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1481 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1482 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1483
1484 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1485 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1486
1487 // We have to be careful here as these two calculations can overflow
1488 // 32-bit size_t's.
1489 double used_after_gc_d = (double) used_after_gc;
1490 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1491 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1492
1493 // Let's make sure that they are both under the max heap size, which
1494 // by default will make them fit into a size_t.
1495 double desired_capacity_upper_bound = (double) max_heap_size;
1496 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1497 desired_capacity_upper_bound);
1498 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1499 desired_capacity_upper_bound);
1500
1501 // We can now safely turn them into size_t's.
1502 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1503 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1504
1505 // This assert only makes sense here, before we adjust them
1506 // with respect to the min and max heap size.
1507 assert(minimum_desired_capacity <= maximum_desired_capacity,
1508 "minimum_desired_capacity = " SIZE_FORMAT ", "
1509 "maximum_desired_capacity = " SIZE_FORMAT,
1510 minimum_desired_capacity, maximum_desired_capacity);
1511
1512 // Should not be greater than the heap max size. No need to adjust
1513 // it with respect to the heap min size as it's a lower bound (i.e.,
1514 // we'll try to make the capacity larger than it, not smaller).
1515 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1516 // Should not be less than the heap min size. No need to adjust it
1517 // with respect to the heap max size as it's an upper bound (i.e.,
1518 // we'll try to make the capacity smaller than it, not greater).
1519 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1520
1521 if (capacity_after_gc < minimum_desired_capacity) {
1522 // Don't expand unless it's significant
1523 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1524
1525 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1526 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1527 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1528
1529 expand(expand_bytes);
1530
1531 // No expansion, now see if we want to shrink
1532 } else if (capacity_after_gc > maximum_desired_capacity) {
1533 // Capacity too large, compute shrinking size
1534 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1535
1536 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1537 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1538 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1539
1540 shrink(shrink_bytes);
1541 }
1542 }
1543
1544 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1545 AllocationContext_t context,
1546 bool do_gc,
1547 bool clear_all_soft_refs,
1548 bool expect_null_mutator_alloc_region,
1549 bool* gc_succeeded) {
1550 *gc_succeeded = true;
1551 // Let's attempt the allocation first.
1552 HeapWord* result =
1553 attempt_allocation_at_safepoint(word_size,
1554 context,
1555 expect_null_mutator_alloc_region);
1556 if (result != NULL) {
1557 assert(*gc_succeeded, "sanity");
1558 return result;
1559 }
1560
1561 // In a G1 heap, we're supposed to keep allocation from failing by
1562 // incremental pauses. Therefore, at least for now, we'll favor
1563 // expansion over collection. (This might change in the future if we can
1564 // do something smarter than full collection to satisfy a failed alloc.)
1565 result = expand_and_allocate(word_size, context);
1566 if (result != NULL) {
1567 assert(*gc_succeeded, "sanity");
1568 return result;
1569 }
1570
1571 if (do_gc) {
1572 // Expansion didn't work, we'll try to do a Full GC.
1573 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1574 clear_all_soft_refs);
1575 }
1576
1577 return NULL;
1578 }
1579
1580 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1581 AllocationContext_t context,
1582 bool* succeeded) {
1583 assert_at_safepoint(true /* should_be_vm_thread */);
1584
1585 // Attempts to allocate followed by Full GC.
1586 HeapWord* result =
1587 satisfy_failed_allocation_helper(word_size,
1588 context,
1589 true, /* do_gc */
1590 false, /* clear_all_soft_refs */
1591 false, /* expect_null_mutator_alloc_region */
1592 succeeded);
1593
1594 if (result != NULL || !*succeeded) {
1595 return result;
1596 }
1597
1598 // Attempts to allocate followed by Full GC that will collect all soft references.
1599 result = satisfy_failed_allocation_helper(word_size,
1600 context,
1601 true, /* do_gc */
1602 true, /* clear_all_soft_refs */
1603 true, /* expect_null_mutator_alloc_region */
1604 succeeded);
1605
1606 if (result != NULL || !*succeeded) {
1607 return result;
1608 }
1609
1610 // Attempts to allocate, no GC
1611 result = satisfy_failed_allocation_helper(word_size,
1612 context,
1613 false, /* do_gc */
1614 false, /* clear_all_soft_refs */
1615 true, /* expect_null_mutator_alloc_region */
1616 succeeded);
1617
1618 if (result != NULL) {
1619 assert(*succeeded, "sanity");
1620 return result;
1621 }
1622
1623 assert(!collector_policy()->should_clear_all_soft_refs(),
1624 "Flag should have been handled and cleared prior to this point");
1625
1626 // What else? We might try synchronous finalization later. If the total
1627 // space available is large enough for the allocation, then a more
1628 // complete compaction phase than we've tried so far might be
1629 // appropriate.
1630 assert(*succeeded, "sanity");
1631 return NULL;
1632 }
1633
1634 // Attempting to expand the heap sufficiently
1635 // to support an allocation of the given "word_size". If
1636 // successful, perform the allocation and return the address of the
1637 // allocated block, or else "NULL".
1638
1639 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1640 assert_at_safepoint(true /* should_be_vm_thread */);
1641
1642 verify_region_sets_optional();
1643
1644 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1645 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1646 word_size * HeapWordSize);
1647
1648
1649 if (expand(expand_bytes)) {
1650 _hrm.verify_optional();
1651 verify_region_sets_optional();
1652 return attempt_allocation_at_safepoint(word_size,
1653 context,
1654 false /* expect_null_mutator_alloc_region */);
1655 }
1656 return NULL;
1657 }
1658
1659 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1660 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1661 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1662 HeapRegion::GrainBytes);
1663
1664 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1665 expand_bytes, aligned_expand_bytes);
1666
1667 if (is_maximal_no_gc()) {
1668 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1669 return false;
1670 }
1671
1672 double expand_heap_start_time_sec = os::elapsedTime();
1673 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1674 assert(regions_to_expand > 0, "Must expand by at least one region");
1675
1676 uint expanded_by = _hrm.expand_by(regions_to_expand);
1677 if (expand_time_ms != NULL) {
1678 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1679 }
1680
1681 if (expanded_by > 0) {
1682 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1683 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1684 g1_policy()->record_new_heap_size(num_regions());
1685 } else {
1686 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1687
1688 // The expansion of the virtual storage space was unsuccessful.
1689 // Let's see if it was because we ran out of swap.
1690 if (G1ExitOnExpansionFailure &&
1691 _hrm.available() >= regions_to_expand) {
1692 // We had head room...
1693 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1694 }
1695 }
1696 return regions_to_expand > 0;
1697 }
1698
1699 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1700 size_t aligned_shrink_bytes =
1701 ReservedSpace::page_align_size_down(shrink_bytes);
1702 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1703 HeapRegion::GrainBytes);
1704 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1705
1706 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1707 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1708
1709
1710 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1711 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1712 if (num_regions_removed > 0) {
1713 g1_policy()->record_new_heap_size(num_regions());
1714 } else {
1715 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1716 }
1717 }
1718
1719 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1720 verify_region_sets_optional();
1721
1722 // We should only reach here at the end of a Full GC which means we
1723 // should not not be holding to any GC alloc regions. The method
1724 // below will make sure of that and do any remaining clean up.
1725 _allocator->abandon_gc_alloc_regions();
1726
1727 // Instead of tearing down / rebuilding the free lists here, we
1728 // could instead use the remove_all_pending() method on free_list to
1729 // remove only the ones that we need to remove.
1730 tear_down_region_sets(true /* free_list_only */);
1731 shrink_helper(shrink_bytes);
1732 rebuild_region_sets(true /* free_list_only */);
1733
1734 _hrm.verify_optional();
1735 verify_region_sets_optional();
1736 }
1737
1738 // Public methods.
1739
1740 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1741 CollectedHeap(),
1742 _g1_policy(policy_),
1743 _dirty_card_queue_set(false),
1744 _is_alive_closure_cm(this),
1745 _is_alive_closure_stw(this),
1746 _ref_processor_cm(NULL),
1747 _ref_processor_stw(NULL),
1748 _bot_shared(NULL),
1749 _cg1r(NULL),
1750 _g1mm(NULL),
1751 _refine_cte_cl(NULL),
1752 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1753 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1754 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1755 _humongous_reclaim_candidates(),
1756 _has_humongous_reclaim_candidates(false),
1757 _archive_allocator(NULL),
1758 _free_regions_coming(false),
1759 _young_list(new YoungList(this)),
1760 _gc_time_stamp(0),
1761 _summary_bytes_used(0),
1762 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1763 _old_evac_stats(OldPLABSize, PLABWeight),
1764 _expand_heap_after_alloc_failure(true),
1765 _old_marking_cycles_started(0),
1766 _old_marking_cycles_completed(0),
1767 _heap_summary_sent(false),
1768 _in_cset_fast_test(),
1769 _dirty_cards_region_list(NULL),
1770 _worker_cset_start_region(NULL),
1771 _worker_cset_start_region_time_stamp(NULL),
1772 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1773 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1774 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1775 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1776
1777 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1778 /* are_GC_task_threads */true,
1779 /* are_ConcurrentGC_threads */false);
1780 _workers->initialize_workers();
1781
1782 _allocator = G1Allocator::create_allocator(this);
1783 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1784
1785 // Override the default _filler_array_max_size so that no humongous filler
1786 // objects are created.
1787 _filler_array_max_size = _humongous_object_threshold_in_words;
1788
1789 uint n_queues = ParallelGCThreads;
1790 _task_queues = new RefToScanQueueSet(n_queues);
1791
1792 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1793 assert(n_rem_sets > 0, "Invariant.");
1794
1795 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1796 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1797 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1798
1799 for (uint i = 0; i < n_queues; i++) {
1800 RefToScanQueue* q = new RefToScanQueue();
1801 q->initialize();
1802 _task_queues->register_queue(i, q);
1803 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1804 }
1805 clear_cset_start_regions();
1806
1807 // Initialize the G1EvacuationFailureALot counters and flags.
1808 NOT_PRODUCT(reset_evacuation_should_fail();)
1809
1810 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1811 }
1812
1813 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1814 size_t size,
1815 size_t translation_factor) {
1816 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1817 // Allocate a new reserved space, preferring to use large pages.
1818 ReservedSpace rs(size, preferred_page_size);
1819 G1RegionToSpaceMapper* result =
1820 G1RegionToSpaceMapper::create_mapper(rs,
1821 size,
1822 rs.alignment(),
1823 HeapRegion::GrainBytes,
1824 translation_factor,
1825 mtGC);
1826 if (TracePageSizes) {
1827 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1828 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1829 }
1830 return result;
1831 }
1832
1833 jint G1CollectedHeap::initialize() {
1834 CollectedHeap::pre_initialize();
1835 os::enable_vtime();
1836
1837 // Necessary to satisfy locking discipline assertions.
1838
1839 MutexLocker x(Heap_lock);
1840
1841 // While there are no constraints in the GC code that HeapWordSize
1842 // be any particular value, there are multiple other areas in the
1843 // system which believe this to be true (e.g. oop->object_size in some
1844 // cases incorrectly returns the size in wordSize units rather than
1845 // HeapWordSize).
1846 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1847
1848 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1849 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1850 size_t heap_alignment = collector_policy()->heap_alignment();
1851
1852 // Ensure that the sizes are properly aligned.
1853 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1854 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1855 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1856
1857 _refine_cte_cl = new RefineCardTableEntryClosure();
1858
1859 jint ecode = JNI_OK;
1860 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1861 if (_cg1r == NULL) {
1862 return ecode;
1863 }
1864
1865 // Reserve the maximum.
1866
1867 // When compressed oops are enabled, the preferred heap base
1868 // is calculated by subtracting the requested size from the
1869 // 32Gb boundary and using the result as the base address for
1870 // heap reservation. If the requested size is not aligned to
1871 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1872 // into the ReservedHeapSpace constructor) then the actual
1873 // base of the reserved heap may end up differing from the
1874 // address that was requested (i.e. the preferred heap base).
1875 // If this happens then we could end up using a non-optimal
1876 // compressed oops mode.
1877
1878 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1879 heap_alignment);
1880
1881 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1882
1883 // Create the barrier set for the entire reserved region.
1884 G1SATBCardTableLoggingModRefBS* bs
1885 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1886 bs->initialize();
1887 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1888 set_barrier_set(bs);
1889
1890 // Also create a G1 rem set.
1891 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1892
1893 // Carve out the G1 part of the heap.
1894
1895 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1896 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1897 G1RegionToSpaceMapper* heap_storage =
1898 G1RegionToSpaceMapper::create_mapper(g1_rs,
1899 g1_rs.size(),
1900 page_size,
1901 HeapRegion::GrainBytes,
1902 1,
1903 mtJavaHeap);
1904 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1905 max_byte_size, page_size,
1906 heap_rs.base(),
1907 heap_rs.size());
1908 heap_storage->set_mapping_changed_listener(&_listener);
1909
1910 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1911 G1RegionToSpaceMapper* bot_storage =
1912 create_aux_memory_mapper("Block offset table",
1913 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1914 G1BlockOffsetSharedArray::heap_map_factor());
1915
1916 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1917 G1RegionToSpaceMapper* cardtable_storage =
1918 create_aux_memory_mapper("Card table",
1919 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1920 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1921
1922 G1RegionToSpaceMapper* card_counts_storage =
1923 create_aux_memory_mapper("Card counts table",
1924 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1925 G1CardCounts::heap_map_factor());
1926
1927 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1928 G1RegionToSpaceMapper* prev_bitmap_storage =
1929 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1930 G1RegionToSpaceMapper* next_bitmap_storage =
1931 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1932
1933 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1934 g1_barrier_set()->initialize(cardtable_storage);
1935 // Do later initialization work for concurrent refinement.
1936 _cg1r->init(card_counts_storage);
1937
1938 // 6843694 - ensure that the maximum region index can fit
1939 // in the remembered set structures.
1940 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1941 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1942
1943 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1944 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1945 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1946 "too many cards per region");
1947
1948 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1949
1950 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1951
1952 {
1953 HeapWord* start = _hrm.reserved().start();
1954 HeapWord* end = _hrm.reserved().end();
1955 size_t granularity = HeapRegion::GrainBytes;
1956
1957 _in_cset_fast_test.initialize(start, end, granularity);
1958 _humongous_reclaim_candidates.initialize(start, end, granularity);
1959 }
1960
1961 // Create the ConcurrentMark data structure and thread.
1962 // (Must do this late, so that "max_regions" is defined.)
1963 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1964 if (_cm == NULL || !_cm->completed_initialization()) {
1965 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1966 return JNI_ENOMEM;
1967 }
1968 _cmThread = _cm->cmThread();
1969
1970 // Initialize the from_card cache structure of HeapRegionRemSet.
1971 HeapRegionRemSet::init_heap(max_regions());
1972
1973 // Now expand into the initial heap size.
1974 if (!expand(init_byte_size)) {
1975 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1976 return JNI_ENOMEM;
1977 }
1978
1979 // Perform any initialization actions delegated to the policy.
1980 g1_policy()->init();
1981
1982 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1983 SATB_Q_FL_lock,
1984 G1SATBProcessCompletedThreshold,
1985 Shared_SATB_Q_lock);
1986
1987 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1988 DirtyCardQ_CBL_mon,
1989 DirtyCardQ_FL_lock,
1990 concurrent_g1_refine()->yellow_zone(),
1991 concurrent_g1_refine()->red_zone(),
1992 Shared_DirtyCardQ_lock);
1993
1994 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1995 DirtyCardQ_CBL_mon,
1996 DirtyCardQ_FL_lock,
1997 -1, // never trigger processing
1998 -1, // no limit on length
1999 Shared_DirtyCardQ_lock,
2000 &JavaThread::dirty_card_queue_set());
2001
2002 // Here we allocate the dummy HeapRegion that is required by the
2003 // G1AllocRegion class.
2004 HeapRegion* dummy_region = _hrm.get_dummy_region();
2005
2006 // We'll re-use the same region whether the alloc region will
2007 // require BOT updates or not and, if it doesn't, then a non-young
2008 // region will complain that it cannot support allocations without
2009 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2010 dummy_region->set_eden();
2011 // Make sure it's full.
2012 dummy_region->set_top(dummy_region->end());
2013 G1AllocRegion::setup(this, dummy_region);
2014
2015 _allocator->init_mutator_alloc_region();
2016
2017 // Do create of the monitoring and management support so that
2018 // values in the heap have been properly initialized.
2019 _g1mm = new G1MonitoringSupport(this);
2020
2021 G1StringDedup::initialize();
2022
2023 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2024 for (uint i = 0; i < ParallelGCThreads; i++) {
2025 new (&_preserved_objs[i]) OopAndMarkOopStack();
2026 }
2027
2028 return JNI_OK;
2029 }
2030
2031 void G1CollectedHeap::stop() {
2032 // Stop all concurrent threads. We do this to make sure these threads
2033 // do not continue to execute and access resources (e.g. logging)
2034 // that are destroyed during shutdown.
2035 _cg1r->stop();
2036 _cmThread->stop();
2037 if (G1StringDedup::is_enabled()) {
2038 G1StringDedup::stop();
2039 }
2040 }
2041
2042 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2043 return HeapRegion::max_region_size();
2044 }
2045
2046 void G1CollectedHeap::post_initialize() {
2047 CollectedHeap::post_initialize();
2048 ref_processing_init();
2049 }
2050
2051 void G1CollectedHeap::ref_processing_init() {
2052 // Reference processing in G1 currently works as follows:
2053 //
2054 // * There are two reference processor instances. One is
2055 // used to record and process discovered references
2056 // during concurrent marking; the other is used to
2057 // record and process references during STW pauses
2058 // (both full and incremental).
2059 // * Both ref processors need to 'span' the entire heap as
2060 // the regions in the collection set may be dotted around.
2061 //
2062 // * For the concurrent marking ref processor:
2063 // * Reference discovery is enabled at initial marking.
2064 // * Reference discovery is disabled and the discovered
2065 // references processed etc during remarking.
2066 // * Reference discovery is MT (see below).
2067 // * Reference discovery requires a barrier (see below).
2068 // * Reference processing may or may not be MT
2069 // (depending on the value of ParallelRefProcEnabled
2070 // and ParallelGCThreads).
2071 // * A full GC disables reference discovery by the CM
2072 // ref processor and abandons any entries on it's
2073 // discovered lists.
2074 //
2075 // * For the STW processor:
2076 // * Non MT discovery is enabled at the start of a full GC.
2077 // * Processing and enqueueing during a full GC is non-MT.
2078 // * During a full GC, references are processed after marking.
2079 //
2080 // * Discovery (may or may not be MT) is enabled at the start
2081 // of an incremental evacuation pause.
2082 // * References are processed near the end of a STW evacuation pause.
2083 // * For both types of GC:
2084 // * Discovery is atomic - i.e. not concurrent.
2085 // * Reference discovery will not need a barrier.
2086
2087 MemRegion mr = reserved_region();
2088
2089 // Concurrent Mark ref processor
2090 _ref_processor_cm =
2091 new ReferenceProcessor(mr, // span
2092 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2093 // mt processing
2094 ParallelGCThreads,
2095 // degree of mt processing
2096 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2097 // mt discovery
2098 MAX2(ParallelGCThreads, ConcGCThreads),
2099 // degree of mt discovery
2100 false,
2101 // Reference discovery is not atomic
2102 &_is_alive_closure_cm);
2103 // is alive closure
2104 // (for efficiency/performance)
2105
2106 // STW ref processor
2107 _ref_processor_stw =
2108 new ReferenceProcessor(mr, // span
2109 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2110 // mt processing
2111 ParallelGCThreads,
2112 // degree of mt processing
2113 (ParallelGCThreads > 1),
2114 // mt discovery
2115 ParallelGCThreads,
2116 // degree of mt discovery
2117 true,
2118 // Reference discovery is atomic
2119 &_is_alive_closure_stw);
2120 // is alive closure
2121 // (for efficiency/performance)
2122 }
2123
2124 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2125 return g1_policy();
2126 }
2127
2128 size_t G1CollectedHeap::capacity() const {
2129 return _hrm.length() * HeapRegion::GrainBytes;
2130 }
2131
2132 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2133 hr->reset_gc_time_stamp();
2134 }
2135
2136 #ifndef PRODUCT
2137
2138 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2139 private:
2140 unsigned _gc_time_stamp;
2141 bool _failures;
2142
2143 public:
2144 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2145 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2146
2147 virtual bool doHeapRegion(HeapRegion* hr) {
2148 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2149 if (_gc_time_stamp != region_gc_time_stamp) {
2150 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2151 region_gc_time_stamp, _gc_time_stamp);
2152 _failures = true;
2153 }
2154 return false;
2155 }
2156
2157 bool failures() { return _failures; }
2158 };
2159
2160 void G1CollectedHeap::check_gc_time_stamps() {
2161 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2162 heap_region_iterate(&cl);
2163 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2164 }
2165 #endif // PRODUCT
2166
2167 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2168 _cg1r->hot_card_cache()->drain(cl, worker_i);
2169 }
2170
2171 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2172 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2173 size_t n_completed_buffers = 0;
2174 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2175 n_completed_buffers++;
2176 }
2177 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2178 dcqs.clear_n_completed_buffers();
2179 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2180 }
2181
2182 // Computes the sum of the storage used by the various regions.
2183 size_t G1CollectedHeap::used() const {
2184 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2185 if (_archive_allocator != NULL) {
2186 result += _archive_allocator->used();
2187 }
2188 return result;
2189 }
2190
2191 size_t G1CollectedHeap::used_unlocked() const {
2192 return _summary_bytes_used;
2193 }
2194
2195 class SumUsedClosure: public HeapRegionClosure {
2196 size_t _used;
2197 public:
2198 SumUsedClosure() : _used(0) {}
2199 bool doHeapRegion(HeapRegion* r) {
2200 _used += r->used();
2201 return false;
2202 }
2203 size_t result() { return _used; }
2204 };
2205
2206 size_t G1CollectedHeap::recalculate_used() const {
2207 double recalculate_used_start = os::elapsedTime();
2208
2209 SumUsedClosure blk;
2210 heap_region_iterate(&blk);
2211
2212 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2213 return blk.result();
2214 }
2215
2216 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2217 switch (cause) {
2218 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2219 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2220 case GCCause::_update_allocation_context_stats_inc: return true;
2221 case GCCause::_wb_conc_mark: return true;
2222 default : return false;
2223 }
2224 }
2225
2226 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2227 switch (cause) {
2228 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2229 case GCCause::_g1_humongous_allocation: return true;
2230 default: return is_user_requested_concurrent_full_gc(cause);
2231 }
2232 }
2233
2234 #ifndef PRODUCT
2235 void G1CollectedHeap::allocate_dummy_regions() {
2236 // Let's fill up most of the region
2237 size_t word_size = HeapRegion::GrainWords - 1024;
2238 // And as a result the region we'll allocate will be humongous.
2239 guarantee(is_humongous(word_size), "sanity");
2240
2241 // _filler_array_max_size is set to humongous object threshold
2242 // but temporarily change it to use CollectedHeap::fill_with_object().
2243 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2244
2245 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2246 // Let's use the existing mechanism for the allocation
2247 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2248 AllocationContext::system());
2249 if (dummy_obj != NULL) {
2250 MemRegion mr(dummy_obj, word_size);
2251 CollectedHeap::fill_with_object(mr);
2252 } else {
2253 // If we can't allocate once, we probably cannot allocate
2254 // again. Let's get out of the loop.
2255 break;
2256 }
2257 }
2258 }
2259 #endif // !PRODUCT
2260
2261 void G1CollectedHeap::increment_old_marking_cycles_started() {
2262 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2263 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2264 "Wrong marking cycle count (started: %d, completed: %d)",
2265 _old_marking_cycles_started, _old_marking_cycles_completed);
2266
2267 _old_marking_cycles_started++;
2268 }
2269
2270 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2271 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2272
2273 // We assume that if concurrent == true, then the caller is a
2274 // concurrent thread that was joined the Suspendible Thread
2275 // Set. If there's ever a cheap way to check this, we should add an
2276 // assert here.
2277
2278 // Given that this method is called at the end of a Full GC or of a
2279 // concurrent cycle, and those can be nested (i.e., a Full GC can
2280 // interrupt a concurrent cycle), the number of full collections
2281 // completed should be either one (in the case where there was no
2282 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2283 // behind the number of full collections started.
2284
2285 // This is the case for the inner caller, i.e. a Full GC.
2286 assert(concurrent ||
2287 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2288 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2289 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2290 "is inconsistent with _old_marking_cycles_completed = %u",
2291 _old_marking_cycles_started, _old_marking_cycles_completed);
2292
2293 // This is the case for the outer caller, i.e. the concurrent cycle.
2294 assert(!concurrent ||
2295 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2296 "for outer caller (concurrent cycle): "
2297 "_old_marking_cycles_started = %u "
2298 "is inconsistent with _old_marking_cycles_completed = %u",
2299 _old_marking_cycles_started, _old_marking_cycles_completed);
2300
2301 _old_marking_cycles_completed += 1;
2302
2303 // We need to clear the "in_progress" flag in the CM thread before
2304 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2305 // is set) so that if a waiter requests another System.gc() it doesn't
2306 // incorrectly see that a marking cycle is still in progress.
2307 if (concurrent) {
2308 _cmThread->set_idle();
2309 }
2310
2311 // This notify_all() will ensure that a thread that called
2312 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2313 // and it's waiting for a full GC to finish will be woken up. It is
2314 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2315 FullGCCount_lock->notify_all();
2316 }
2317
2318 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2319 GCIdMarkAndRestore conc_gc_id_mark;
2320 collector_state()->set_concurrent_cycle_started(true);
2321 _gc_timer_cm->register_gc_start(start_time);
2322
2323 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2324 trace_heap_before_gc(_gc_tracer_cm);
2325 _cmThread->set_gc_id(GCId::current());
2326 }
2327
2328 void G1CollectedHeap::register_concurrent_cycle_end() {
2329 if (collector_state()->concurrent_cycle_started()) {
2330 Ticks end_tick = Ticks::now();
2331 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2332 if (_cm->has_aborted()) {
2333 _gc_tracer_cm->report_concurrent_mode_failure();
2334
2335 if (_cm->concurrent_marking_from_roots()) {
2336 _gc_timer_cm->register_gc_concurrent_end(end_tick);
2337 }
2338 }
2339
2340 _gc_timer_cm->register_gc_end(end_tick);
2341 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2342
2343 // Clear state variables to prepare for the next concurrent cycle.
2344 collector_state()->set_concurrent_cycle_started(false);
2345 _heap_summary_sent = false;
2346 }
2347 }
2348
2349 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2350 if (collector_state()->concurrent_cycle_started()) {
2351 // This function can be called when:
2352 // the cleanup pause is run
2353 // the concurrent cycle is aborted before the cleanup pause.
2354 // the concurrent cycle is aborted after the cleanup pause,
2355 // but before the concurrent cycle end has been registered.
2356 // Make sure that we only send the heap information once.
2357 if (!_heap_summary_sent) {
2358 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2359 trace_heap_after_gc(_gc_tracer_cm);
2360 _heap_summary_sent = true;
2361 }
2362 }
2363 }
2364
2365 void G1CollectedHeap::collect(GCCause::Cause cause) {
2366 assert_heap_not_locked();
2367
2368 uint gc_count_before;
2369 uint old_marking_count_before;
2370 uint full_gc_count_before;
2371 bool retry_gc;
2372
2373 do {
2374 retry_gc = false;
2375
2376 {
2377 MutexLocker ml(Heap_lock);
2378
2379 // Read the GC count while holding the Heap_lock
2380 gc_count_before = total_collections();
2381 full_gc_count_before = total_full_collections();
2382 old_marking_count_before = _old_marking_cycles_started;
2383 }
2384
2385 if (should_do_concurrent_full_gc(cause)) {
2386 // Schedule an initial-mark evacuation pause that will start a
2387 // concurrent cycle. We're setting word_size to 0 which means that
2388 // we are not requesting a post-GC allocation.
2389 VM_G1IncCollectionPause op(gc_count_before,
2390 0, /* word_size */
2391 true, /* should_initiate_conc_mark */
2392 g1_policy()->max_pause_time_ms(),
2393 cause);
2394 op.set_allocation_context(AllocationContext::current());
2395
2396 VMThread::execute(&op);
2397 if (!op.pause_succeeded()) {
2398 if (old_marking_count_before == _old_marking_cycles_started) {
2399 retry_gc = op.should_retry_gc();
2400 } else {
2401 // A Full GC happened while we were trying to schedule the
2402 // initial-mark GC. No point in starting a new cycle given
2403 // that the whole heap was collected anyway.
2404 }
2405
2406 if (retry_gc) {
2407 if (GC_locker::is_active_and_needs_gc()) {
2408 GC_locker::stall_until_clear();
2409 }
2410 }
2411 }
2412 } else {
2413 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2414 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2415
2416 // Schedule a standard evacuation pause. We're setting word_size
2417 // to 0 which means that we are not requesting a post-GC allocation.
2418 VM_G1IncCollectionPause op(gc_count_before,
2419 0, /* word_size */
2420 false, /* should_initiate_conc_mark */
2421 g1_policy()->max_pause_time_ms(),
2422 cause);
2423 VMThread::execute(&op);
2424 } else {
2425 // Schedule a Full GC.
2426 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2427 VMThread::execute(&op);
2428 }
2429 }
2430 } while (retry_gc);
2431 }
2432
2433 bool G1CollectedHeap::is_in(const void* p) const {
2434 if (_hrm.reserved().contains(p)) {
2435 // Given that we know that p is in the reserved space,
2436 // heap_region_containing() should successfully
2437 // return the containing region.
2438 HeapRegion* hr = heap_region_containing(p);
2439 return hr->is_in(p);
2440 } else {
2441 return false;
2442 }
2443 }
2444
2445 #ifdef ASSERT
2446 bool G1CollectedHeap::is_in_exact(const void* p) const {
2447 bool contains = reserved_region().contains(p);
2448 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2449 if (contains && available) {
2450 return true;
2451 } else {
2452 return false;
2453 }
2454 }
2455 #endif
2456
2457 bool G1CollectedHeap::obj_in_cs(oop obj) {
2458 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2459 return r != NULL && r->in_collection_set();
2460 }
2461
2462 // Iteration functions.
2463
2464 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2465
2466 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2467 ExtendedOopClosure* _cl;
2468 public:
2469 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2470 bool doHeapRegion(HeapRegion* r) {
2471 if (!r->is_continues_humongous()) {
2472 r->oop_iterate(_cl);
2473 }
2474 return false;
2475 }
2476 };
2477
2478 // Iterates an ObjectClosure over all objects within a HeapRegion.
2479
2480 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2481 ObjectClosure* _cl;
2482 public:
2483 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2484 bool doHeapRegion(HeapRegion* r) {
2485 if (!r->is_continues_humongous()) {
2486 r->object_iterate(_cl);
2487 }
2488 return false;
2489 }
2490 };
2491
2492 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2493 IterateObjectClosureRegionClosure blk(cl);
2494 heap_region_iterate(&blk);
2495 }
2496
2497 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2498 _hrm.iterate(cl);
2499 }
2500
2501 void
2502 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2503 uint worker_id,
2504 HeapRegionClaimer *hrclaimer,
2505 bool concurrent) const {
2506 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2507 }
2508
2509 // Clear the cached CSet starting regions and (more importantly)
2510 // the time stamps. Called when we reset the GC time stamp.
2511 void G1CollectedHeap::clear_cset_start_regions() {
2512 assert(_worker_cset_start_region != NULL, "sanity");
2513 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2514
2515 for (uint i = 0; i < ParallelGCThreads; i++) {
2516 _worker_cset_start_region[i] = NULL;
2517 _worker_cset_start_region_time_stamp[i] = 0;
2518 }
2519 }
2520
2521 // Given the id of a worker, obtain or calculate a suitable
2522 // starting region for iterating over the current collection set.
2523 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2524 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2525
2526 HeapRegion* result = NULL;
2527 unsigned gc_time_stamp = get_gc_time_stamp();
2528
2529 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2530 // Cached starting region for current worker was set
2531 // during the current pause - so it's valid.
2532 // Note: the cached starting heap region may be NULL
2533 // (when the collection set is empty).
2534 result = _worker_cset_start_region[worker_i];
2535 assert(result == NULL || result->in_collection_set(), "sanity");
2536 return result;
2537 }
2538
2539 // The cached entry was not valid so let's calculate
2540 // a suitable starting heap region for this worker.
2541
2542 // We want the parallel threads to start their collection
2543 // set iteration at different collection set regions to
2544 // avoid contention.
2545 // If we have:
2546 // n collection set regions
2547 // p threads
2548 // Then thread t will start at region floor ((t * n) / p)
2549
2550 result = g1_policy()->collection_set();
2551 uint cs_size = g1_policy()->cset_region_length();
2552 uint active_workers = workers()->active_workers();
2553
2554 uint end_ind = (cs_size * worker_i) / active_workers;
2555 uint start_ind = 0;
2556
2557 if (worker_i > 0 &&
2558 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2559 // Previous workers starting region is valid
2560 // so let's iterate from there
2561 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2562 result = _worker_cset_start_region[worker_i - 1];
2563 }
2564
2565 for (uint i = start_ind; i < end_ind; i++) {
2566 result = result->next_in_collection_set();
2567 }
2568
2569 // Note: the calculated starting heap region may be NULL
2570 // (when the collection set is empty).
2571 assert(result == NULL || result->in_collection_set(), "sanity");
2572 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2573 "should be updated only once per pause");
2574 _worker_cset_start_region[worker_i] = result;
2575 OrderAccess::storestore();
2576 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2577 return result;
2578 }
2579
2580 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2581 HeapRegion* r = g1_policy()->collection_set();
2582 while (r != NULL) {
2583 HeapRegion* next = r->next_in_collection_set();
2584 if (cl->doHeapRegion(r)) {
2585 cl->incomplete();
2586 return;
2587 }
2588 r = next;
2589 }
2590 }
2591
2592 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2593 HeapRegionClosure *cl) {
2594 if (r == NULL) {
2595 // The CSet is empty so there's nothing to do.
2596 return;
2597 }
2598
2599 assert(r->in_collection_set(),
2600 "Start region must be a member of the collection set.");
2601 HeapRegion* cur = r;
2602 while (cur != NULL) {
2603 HeapRegion* next = cur->next_in_collection_set();
2604 if (cl->doHeapRegion(cur) && false) {
2605 cl->incomplete();
2606 return;
2607 }
2608 cur = next;
2609 }
2610 cur = g1_policy()->collection_set();
2611 while (cur != r) {
2612 HeapRegion* next = cur->next_in_collection_set();
2613 if (cl->doHeapRegion(cur) && false) {
2614 cl->incomplete();
2615 return;
2616 }
2617 cur = next;
2618 }
2619 }
2620
2621 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2622 HeapRegion* result = _hrm.next_region_in_heap(from);
2623 while (result != NULL && result->is_pinned()) {
2624 result = _hrm.next_region_in_heap(result);
2625 }
2626 return result;
2627 }
2628
2629 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2630 HeapRegion* hr = heap_region_containing(addr);
2631 return hr->block_start(addr);
2632 }
2633
2634 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2635 HeapRegion* hr = heap_region_containing(addr);
2636 return hr->block_size(addr);
2637 }
2638
2639 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2640 HeapRegion* hr = heap_region_containing(addr);
2641 return hr->block_is_obj(addr);
2642 }
2643
2644 bool G1CollectedHeap::supports_tlab_allocation() const {
2645 return true;
2646 }
2647
2648 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2649 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2650 }
2651
2652 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2653 return young_list()->eden_used_bytes();
2654 }
2655
2656 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2657 // must be equal to the humongous object limit.
2658 size_t G1CollectedHeap::max_tlab_size() const {
2659 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2660 }
2661
2662 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2663 AllocationContext_t context = AllocationContext::current();
2664 return _allocator->unsafe_max_tlab_alloc(context);
2665 }
2666
2667 size_t G1CollectedHeap::max_capacity() const {
2668 return _hrm.reserved().byte_size();
2669 }
2670
2671 jlong G1CollectedHeap::millis_since_last_gc() {
2672 // assert(false, "NYI");
2673 return 0;
2674 }
2675
2676 void G1CollectedHeap::prepare_for_verify() {
2677 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2678 ensure_parsability(false);
2679 }
2680 g1_rem_set()->prepare_for_verify();
2681 }
2682
2683 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2684 VerifyOption vo) {
2685 switch (vo) {
2686 case VerifyOption_G1UsePrevMarking:
2687 return hr->obj_allocated_since_prev_marking(obj);
2688 case VerifyOption_G1UseNextMarking:
2689 return hr->obj_allocated_since_next_marking(obj);
2690 case VerifyOption_G1UseMarkWord:
2691 return false;
2692 default:
2693 ShouldNotReachHere();
2694 }
2695 return false; // keep some compilers happy
2696 }
2697
2698 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2699 switch (vo) {
2700 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2701 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2702 case VerifyOption_G1UseMarkWord: return NULL;
2703 default: ShouldNotReachHere();
2704 }
2705 return NULL; // keep some compilers happy
2706 }
2707
2708 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2709 switch (vo) {
2710 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2711 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2712 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2713 default: ShouldNotReachHere();
2714 }
2715 return false; // keep some compilers happy
2716 }
2717
2718 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2719 switch (vo) {
2720 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2721 case VerifyOption_G1UseNextMarking: return "NTAMS";
2722 case VerifyOption_G1UseMarkWord: return "NONE";
2723 default: ShouldNotReachHere();
2724 }
2725 return NULL; // keep some compilers happy
2726 }
2727
2728 class VerifyRootsClosure: public OopClosure {
2729 private:
2730 G1CollectedHeap* _g1h;
2731 VerifyOption _vo;
2732 bool _failures;
2733 public:
2734 // _vo == UsePrevMarking -> use "prev" marking information,
2735 // _vo == UseNextMarking -> use "next" marking information,
2736 // _vo == UseMarkWord -> use mark word from object header.
2737 VerifyRootsClosure(VerifyOption vo) :
2738 _g1h(G1CollectedHeap::heap()),
2739 _vo(vo),
2740 _failures(false) { }
2741
2742 bool failures() { return _failures; }
2743
2744 template <class T> void do_oop_nv(T* p) {
2745 T heap_oop = oopDesc::load_heap_oop(p);
2746 if (!oopDesc::is_null(heap_oop)) {
2747 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2748 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2749 LogHandle(gc, verify) log;
2750 log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2751 if (_vo == VerifyOption_G1UseMarkWord) {
2752 log.info(" Mark word: " PTR_FORMAT, p2i(obj->mark()));
2753 }
2754 ResourceMark rm;
2755 obj->print_on(log.info_stream());
2756 _failures = true;
2757 }
2758 }
2759 }
2760
2761 void do_oop(oop* p) { do_oop_nv(p); }
2762 void do_oop(narrowOop* p) { do_oop_nv(p); }
2763 };
2764
2765 class G1VerifyCodeRootOopClosure: public OopClosure {
2766 G1CollectedHeap* _g1h;
2767 OopClosure* _root_cl;
2768 nmethod* _nm;
2769 VerifyOption _vo;
2770 bool _failures;
2771
2772 template <class T> void do_oop_work(T* p) {
2773 // First verify that this root is live
2774 _root_cl->do_oop(p);
2775
2776 if (!G1VerifyHeapRegionCodeRoots) {
2777 // We're not verifying the code roots attached to heap region.
2778 return;
2779 }
2780
2781 // Don't check the code roots during marking verification in a full GC
2782 if (_vo == VerifyOption_G1UseMarkWord) {
2783 return;
2784 }
2785
2786 // Now verify that the current nmethod (which contains p) is
2787 // in the code root list of the heap region containing the
2788 // object referenced by p.
2789
2790 T heap_oop = oopDesc::load_heap_oop(p);
2791 if (!oopDesc::is_null(heap_oop)) {
2792 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2793
2794 // Now fetch the region containing the object
2795 HeapRegion* hr = _g1h->heap_region_containing(obj);
2796 HeapRegionRemSet* hrrs = hr->rem_set();
2797 // Verify that the strong code root list for this region
2798 // contains the nmethod
2799 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2800 log_info(gc, verify)("Code root location " PTR_FORMAT " "
2801 "from nmethod " PTR_FORMAT " not in strong "
2802 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2803 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2804 _failures = true;
2805 }
2806 }
2807 }
2808
2809 public:
2810 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2811 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2812
2813 void do_oop(oop* p) { do_oop_work(p); }
2814 void do_oop(narrowOop* p) { do_oop_work(p); }
2815
2816 void set_nmethod(nmethod* nm) { _nm = nm; }
2817 bool failures() { return _failures; }
2818 };
2819
2820 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2821 G1VerifyCodeRootOopClosure* _oop_cl;
2822
2823 public:
2824 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2825 _oop_cl(oop_cl) {}
2826
2827 void do_code_blob(CodeBlob* cb) {
2828 nmethod* nm = cb->as_nmethod_or_null();
2829 if (nm != NULL) {
2830 _oop_cl->set_nmethod(nm);
2831 nm->oops_do(_oop_cl);
2832 }
2833 }
2834 };
2835
2836 class YoungRefCounterClosure : public OopClosure {
2837 G1CollectedHeap* _g1h;
2838 int _count;
2839 public:
2840 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2841 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2842 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2843
2844 int count() { return _count; }
2845 void reset_count() { _count = 0; };
2846 };
2847
2848 class VerifyKlassClosure: public KlassClosure {
2849 YoungRefCounterClosure _young_ref_counter_closure;
2850 OopClosure *_oop_closure;
2851 public:
2852 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2853 void do_klass(Klass* k) {
2854 k->oops_do(_oop_closure);
2855
2856 _young_ref_counter_closure.reset_count();
2857 k->oops_do(&_young_ref_counter_closure);
2858 if (_young_ref_counter_closure.count() > 0) {
2859 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2860 }
2861 }
2862 };
2863
2864 class VerifyLivenessOopClosure: public OopClosure {
2865 G1CollectedHeap* _g1h;
2866 VerifyOption _vo;
2867 public:
2868 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2869 _g1h(g1h), _vo(vo)
2870 { }
2871 void do_oop(narrowOop *p) { do_oop_work(p); }
2872 void do_oop( oop *p) { do_oop_work(p); }
2873
2874 template <class T> void do_oop_work(T *p) {
2875 oop obj = oopDesc::load_decode_heap_oop(p);
2876 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2877 "Dead object referenced by a not dead object");
2878 }
2879 };
2880
2881 class VerifyObjsInRegionClosure: public ObjectClosure {
2882 private:
2883 G1CollectedHeap* _g1h;
2884 size_t _live_bytes;
2885 HeapRegion *_hr;
2886 VerifyOption _vo;
2887 public:
2888 // _vo == UsePrevMarking -> use "prev" marking information,
2889 // _vo == UseNextMarking -> use "next" marking information,
2890 // _vo == UseMarkWord -> use mark word from object header.
2891 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2892 : _live_bytes(0), _hr(hr), _vo(vo) {
2893 _g1h = G1CollectedHeap::heap();
2894 }
2895 void do_object(oop o) {
2896 VerifyLivenessOopClosure isLive(_g1h, _vo);
2897 assert(o != NULL, "Huh?");
2898 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2899 // If the object is alive according to the mark word,
2900 // then verify that the marking information agrees.
2901 // Note we can't verify the contra-positive of the
2902 // above: if the object is dead (according to the mark
2903 // word), it may not be marked, or may have been marked
2904 // but has since became dead, or may have been allocated
2905 // since the last marking.
2906 if (_vo == VerifyOption_G1UseMarkWord) {
2907 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2908 }
2909
2910 o->oop_iterate_no_header(&isLive);
2911 if (!_hr->obj_allocated_since_prev_marking(o)) {
2912 size_t obj_size = o->size(); // Make sure we don't overflow
2913 _live_bytes += (obj_size * HeapWordSize);
2914 }
2915 }
2916 }
2917 size_t live_bytes() { return _live_bytes; }
2918 };
2919
2920 class VerifyArchiveOopClosure: public OopClosure {
2921 public:
2922 VerifyArchiveOopClosure(HeapRegion *hr) { }
2923 void do_oop(narrowOop *p) { do_oop_work(p); }
2924 void do_oop( oop *p) { do_oop_work(p); }
2925
2926 template <class T> void do_oop_work(T *p) {
2927 oop obj = oopDesc::load_decode_heap_oop(p);
2928 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2929 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2930 p2i(p), p2i(obj));
2931 }
2932 };
2933
2934 class VerifyArchiveRegionClosure: public ObjectClosure {
2935 public:
2936 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2937 // Verify that all object pointers are to archive regions.
2938 void do_object(oop o) {
2939 VerifyArchiveOopClosure checkOop(NULL);
2940 assert(o != NULL, "Should not be here for NULL oops");
2941 o->oop_iterate_no_header(&checkOop);
2942 }
2943 };
2944
2945 class VerifyRegionClosure: public HeapRegionClosure {
2946 private:
2947 bool _par;
2948 VerifyOption _vo;
2949 bool _failures;
2950 public:
2951 // _vo == UsePrevMarking -> use "prev" marking information,
2952 // _vo == UseNextMarking -> use "next" marking information,
2953 // _vo == UseMarkWord -> use mark word from object header.
2954 VerifyRegionClosure(bool par, VerifyOption vo)
2955 : _par(par),
2956 _vo(vo),
2957 _failures(false) {}
2958
2959 bool failures() {
2960 return _failures;
2961 }
2962
2963 bool doHeapRegion(HeapRegion* r) {
2964 // For archive regions, verify there are no heap pointers to
2965 // non-pinned regions. For all others, verify liveness info.
2966 if (r->is_archive()) {
2967 VerifyArchiveRegionClosure verify_oop_pointers(r);
2968 r->object_iterate(&verify_oop_pointers);
2969 return true;
2970 }
2971 if (!r->is_continues_humongous()) {
2972 bool failures = false;
2973 r->verify(_vo, &failures);
2974 if (failures) {
2975 _failures = true;
2976 } else if (!r->is_starts_humongous()) {
2977 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2978 r->object_iterate(¬_dead_yet_cl);
2979 if (_vo != VerifyOption_G1UseNextMarking) {
2980 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2981 log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2982 p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2983 _failures = true;
2984 }
2985 } else {
2986 // When vo == UseNextMarking we cannot currently do a sanity
2987 // check on the live bytes as the calculation has not been
2988 // finalized yet.
2989 }
2990 }
2991 }
2992 return false; // stop the region iteration if we hit a failure
2993 }
2994 };
2995
2996 // This is the task used for parallel verification of the heap regions
2997
2998 class G1ParVerifyTask: public AbstractGangTask {
2999 private:
3000 G1CollectedHeap* _g1h;
3001 VerifyOption _vo;
3002 bool _failures;
3003 HeapRegionClaimer _hrclaimer;
3004
3005 public:
3006 // _vo == UsePrevMarking -> use "prev" marking information,
3007 // _vo == UseNextMarking -> use "next" marking information,
3008 // _vo == UseMarkWord -> use mark word from object header.
3009 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3010 AbstractGangTask("Parallel verify task"),
3011 _g1h(g1h),
3012 _vo(vo),
3013 _failures(false),
3014 _hrclaimer(g1h->workers()->active_workers()) {}
3015
3016 bool failures() {
3017 return _failures;
3018 }
3019
3020 void work(uint worker_id) {
3021 HandleMark hm;
3022 VerifyRegionClosure blk(true, _vo);
3023 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3024 if (blk.failures()) {
3025 _failures = true;
3026 }
3027 }
3028 };
3029
3030 void G1CollectedHeap::verify(VerifyOption vo) {
3031 if (!SafepointSynchronize::is_at_safepoint()) {
3032 log_info(gc, verify)("Skipping verification. Not at safepoint.");
3033 }
3034
3035 assert(Thread::current()->is_VM_thread(),
3036 "Expected to be executed serially by the VM thread at this point");
3037
3038 log_debug(gc, verify)("Roots");
3039 VerifyRootsClosure rootsCl(vo);
3040 VerifyKlassClosure klassCl(this, &rootsCl);
3041 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3042
3043 // We apply the relevant closures to all the oops in the
3044 // system dictionary, class loader data graph, the string table
3045 // and the nmethods in the code cache.
3046 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3047 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3048
3049 {
3050 G1RootProcessor root_processor(this, 1);
3051 root_processor.process_all_roots(&rootsCl,
3052 &cldCl,
3053 &blobsCl);
3054 }
3055
3056 bool failures = rootsCl.failures() || codeRootsCl.failures();
3057
3058 if (vo != VerifyOption_G1UseMarkWord) {
3059 // If we're verifying during a full GC then the region sets
3060 // will have been torn down at the start of the GC. Therefore
3061 // verifying the region sets will fail. So we only verify
3062 // the region sets when not in a full GC.
3063 log_debug(gc, verify)("HeapRegionSets");
3064 verify_region_sets();
3065 }
3066
3067 log_debug(gc, verify)("HeapRegions");
3068 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3069
3070 G1ParVerifyTask task(this, vo);
3071 workers()->run_task(&task);
3072 if (task.failures()) {
3073 failures = true;
3074 }
3075
3076 } else {
3077 VerifyRegionClosure blk(false, vo);
3078 heap_region_iterate(&blk);
3079 if (blk.failures()) {
3080 failures = true;
3081 }
3082 }
3083
3084 if (G1StringDedup::is_enabled()) {
3085 log_debug(gc, verify)("StrDedup");
3086 G1StringDedup::verify();
3087 }
3088
3089 if (failures) {
3090 log_info(gc, verify)("Heap after failed verification:");
3091 // It helps to have the per-region information in the output to
3092 // help us track down what went wrong. This is why we call
3093 // print_extended_on() instead of print_on().
3094 LogHandle(gc, verify) log;
3095 ResourceMark rm;
3096 print_extended_on(log.info_stream());
3097 }
3098 guarantee(!failures, "there should not have been any failures");
3099 }
3100
3101 double G1CollectedHeap::verify(bool guard, const char* msg) {
3102 double verify_time_ms = 0.0;
3103
3104 if (guard && total_collections() >= VerifyGCStartAt) {
3105 double verify_start = os::elapsedTime();
3106 HandleMark hm; // Discard invalid handles created during verification
3107 prepare_for_verify();
3108 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3109 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3110 }
3111
3112 return verify_time_ms;
3113 }
3114
3115 void G1CollectedHeap::verify_before_gc() {
3116 double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3117 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3118 }
3119
3120 void G1CollectedHeap::verify_after_gc() {
3121 double verify_time_ms = verify(VerifyAfterGC, "After GC");
3122 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3123 }
3124
3125 class PrintRegionClosure: public HeapRegionClosure {
3126 outputStream* _st;
3127 public:
3128 PrintRegionClosure(outputStream* st) : _st(st) {}
3129 bool doHeapRegion(HeapRegion* r) {
3130 r->print_on(_st);
3131 return false;
3132 }
3133 };
3134
3135 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3136 const HeapRegion* hr,
3137 const VerifyOption vo) const {
3138 switch (vo) {
3139 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3140 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3141 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3142 default: ShouldNotReachHere();
3143 }
3144 return false; // keep some compilers happy
3145 }
3146
3147 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3148 const VerifyOption vo) const {
3149 switch (vo) {
3150 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3151 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3152 case VerifyOption_G1UseMarkWord: {
3153 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3154 return !obj->is_gc_marked() && !hr->is_archive();
3155 }
3156 default: ShouldNotReachHere();
3157 }
3158 return false; // keep some compilers happy
3159 }
3160
3161 void G1CollectedHeap::print_on(outputStream* st) const {
3162 st->print(" %-20s", "garbage-first heap");
3163 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3164 capacity()/K, used_unlocked()/K);
3165 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3166 p2i(_hrm.reserved().start()),
3167 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3168 p2i(_hrm.reserved().end()));
3169 st->cr();
3170 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3171 uint young_regions = _young_list->length();
3172 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3173 (size_t) young_regions * HeapRegion::GrainBytes / K);
3174 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3175 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3176 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3177 st->cr();
3178 MetaspaceAux::print_on(st);
3179 }
3180
3181 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3182 print_on(st);
3183
3184 // Print the per-region information.
3185 st->cr();
3186 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
3187 "HS=humongous(starts), HC=humongous(continues), "
3188 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3189 "AC=allocation context, "
3190 "TAMS=top-at-mark-start (previous, next)");
3191 PrintRegionClosure blk(st);
3192 heap_region_iterate(&blk);
3193 }
3194
3195 void G1CollectedHeap::print_on_error(outputStream* st) const {
3196 this->CollectedHeap::print_on_error(st);
3197
3198 if (_cm != NULL) {
3199 st->cr();
3200 _cm->print_on_error(st);
3201 }
3202 }
3203
3204 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3205 workers()->print_worker_threads_on(st);
3206 _cmThread->print_on(st);
3207 st->cr();
3208 _cm->print_worker_threads_on(st);
3209 _cg1r->print_worker_threads_on(st);
3210 if (G1StringDedup::is_enabled()) {
3211 G1StringDedup::print_worker_threads_on(st);
3212 }
3213 }
3214
3215 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3216 workers()->threads_do(tc);
3217 tc->do_thread(_cmThread);
3218 _cg1r->threads_do(tc);
3219 if (G1StringDedup::is_enabled()) {
3220 G1StringDedup::threads_do(tc);
3221 }
3222 }
3223
3224 void G1CollectedHeap::print_tracing_info() const {
3225 // We'll overload this to mean "trace GC pause statistics."
3226 if (TraceYoungGenTime || TraceOldGenTime) {
3227 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3228 // to that.
3229 g1_policy()->print_tracing_info();
3230 }
3231 g1_rem_set()->print_summary_info();
3232 concurrent_mark()->print_summary_info();
3233 g1_policy()->print_yg_surv_rate_info();
3234 }
3235
3236 #ifndef PRODUCT
3237 // Helpful for debugging RSet issues.
3238
3239 class PrintRSetsClosure : public HeapRegionClosure {
3240 private:
3241 const char* _msg;
3242 size_t _occupied_sum;
3243
3244 public:
3245 bool doHeapRegion(HeapRegion* r) {
3246 HeapRegionRemSet* hrrs = r->rem_set();
3247 size_t occupied = hrrs->occupied();
3248 _occupied_sum += occupied;
3249
3250 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
3251 if (occupied == 0) {
3252 tty->print_cr(" RSet is empty");
3253 } else {
3254 hrrs->print();
3255 }
3256 tty->print_cr("----------");
3257 return false;
3258 }
3259
3260 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3261 tty->cr();
3262 tty->print_cr("========================================");
3263 tty->print_cr("%s", msg);
3264 tty->cr();
3265 }
3266
3267 ~PrintRSetsClosure() {
3268 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3269 tty->print_cr("========================================");
3270 tty->cr();
3271 }
3272 };
3273
3274 void G1CollectedHeap::print_cset_rsets() {
3275 PrintRSetsClosure cl("Printing CSet RSets");
3276 collection_set_iterate(&cl);
3277 }
3278
3279 void G1CollectedHeap::print_all_rsets() {
3280 PrintRSetsClosure cl("Printing All RSets");;
3281 heap_region_iterate(&cl);
3282 }
3283 #endif // PRODUCT
3284
3285 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3286 YoungList* young_list = heap()->young_list();
3287
3288 size_t eden_used_bytes = young_list->eden_used_bytes();
3289 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3290
3291 size_t eden_capacity_bytes =
3292 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3293
3294 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3295 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3296 }
3297
3298 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3299 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3300 stats->unused(), stats->used(), stats->region_end_waste(),
3301 stats->regions_filled(), stats->direct_allocated(),
3302 stats->failure_used(), stats->failure_waste());
3303 }
3304
3305 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3306 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3307 gc_tracer->report_gc_heap_summary(when, heap_summary);
3308
3309 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3310 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3311 }
3312
3313
3314 G1CollectedHeap* G1CollectedHeap::heap() {
3315 CollectedHeap* heap = Universe::heap();
3316 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3317 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3318 return (G1CollectedHeap*)heap;
3319 }
3320
3321 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3322 // always_do_update_barrier = false;
3323 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3324 // Fill TLAB's and such
3325 accumulate_statistics_all_tlabs();
3326 ensure_parsability(true);
3327
3328 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3329 }
3330
3331 void G1CollectedHeap::gc_epilogue(bool full) {
3332 // we are at the end of the GC. Total collections has already been increased.
3333 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3334
3335 // FIXME: what is this about?
3336 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3337 // is set.
3338 #if defined(COMPILER2) || INCLUDE_JVMCI
3339 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3340 #endif
3341 // always_do_update_barrier = true;
3342
3343 resize_all_tlabs();
3344 allocation_context_stats().update(full);
3345
3346 // We have just completed a GC. Update the soft reference
3347 // policy with the new heap occupancy
3348 Universe::update_heap_info_at_gc();
3349 }
3350
3351 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3352 uint gc_count_before,
3353 bool* succeeded,
3354 GCCause::Cause gc_cause) {
3355 assert_heap_not_locked_and_not_at_safepoint();
3356 g1_policy()->record_stop_world_start();
3357 VM_G1IncCollectionPause op(gc_count_before,
3358 word_size,
3359 false, /* should_initiate_conc_mark */
3360 g1_policy()->max_pause_time_ms(),
3361 gc_cause);
3362
3363 op.set_allocation_context(AllocationContext::current());
3364 VMThread::execute(&op);
3365
3366 HeapWord* result = op.result();
3367 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3368 assert(result == NULL || ret_succeeded,
3369 "the result should be NULL if the VM did not succeed");
3370 *succeeded = ret_succeeded;
3371
3372 assert_heap_not_locked();
3373 return result;
3374 }
3375
3376 void
3377 G1CollectedHeap::doConcurrentMark() {
3378 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3379 if (!_cmThread->in_progress()) {
3380 _cmThread->set_started();
3381 CGC_lock->notify();
3382 }
3383 }
3384
3385 size_t G1CollectedHeap::pending_card_num() {
3386 size_t extra_cards = 0;
3387 JavaThread *curr = Threads::first();
3388 while (curr != NULL) {
3389 DirtyCardQueue& dcq = curr->dirty_card_queue();
3390 extra_cards += dcq.size();
3391 curr = curr->next();
3392 }
3393 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3394 size_t buffer_size = dcqs.buffer_size();
3395 size_t buffer_num = dcqs.completed_buffers_num();
3396
3397 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3398 // in bytes - not the number of 'entries'. We need to convert
3399 // into a number of cards.
3400 return (buffer_size * buffer_num + extra_cards) / oopSize;
3401 }
3402
3403 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3404 private:
3405 size_t _total_humongous;
3406 size_t _candidate_humongous;
3407
3408 DirtyCardQueue _dcq;
3409
3410 // We don't nominate objects with many remembered set entries, on
3411 // the assumption that such objects are likely still live.
3412 bool is_remset_small(HeapRegion* region) const {
3413 HeapRegionRemSet* const rset = region->rem_set();
3414 return G1EagerReclaimHumongousObjectsWithStaleRefs
3415 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3416 : rset->is_empty();
3417 }
3418
3419 bool is_typeArray_region(HeapRegion* region) const {
3420 return oop(region->bottom())->is_typeArray();
3421 }
3422
3423 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3424 assert(region->is_starts_humongous(), "Must start a humongous object");
3425
3426 // Candidate selection must satisfy the following constraints
3427 // while concurrent marking is in progress:
3428 //
3429 // * In order to maintain SATB invariants, an object must not be
3430 // reclaimed if it was allocated before the start of marking and
3431 // has not had its references scanned. Such an object must have
3432 // its references (including type metadata) scanned to ensure no
3433 // live objects are missed by the marking process. Objects
3434 // allocated after the start of concurrent marking don't need to
3435 // be scanned.
3436 //
3437 // * An object must not be reclaimed if it is on the concurrent
3438 // mark stack. Objects allocated after the start of concurrent
3439 // marking are never pushed on the mark stack.
3440 //
3441 // Nominating only objects allocated after the start of concurrent
3442 // marking is sufficient to meet both constraints. This may miss
3443 // some objects that satisfy the constraints, but the marking data
3444 // structures don't support efficiently performing the needed
3445 // additional tests or scrubbing of the mark stack.
3446 //
3447 // However, we presently only nominate is_typeArray() objects.
3448 // A humongous object containing references induces remembered
3449 // set entries on other regions. In order to reclaim such an
3450 // object, those remembered sets would need to be cleaned up.
3451 //
3452 // We also treat is_typeArray() objects specially, allowing them
3453 // to be reclaimed even if allocated before the start of
3454 // concurrent mark. For this we rely on mark stack insertion to
3455 // exclude is_typeArray() objects, preventing reclaiming an object
3456 // that is in the mark stack. We also rely on the metadata for
3457 // such objects to be built-in and so ensured to be kept live.
3458 // Frequent allocation and drop of large binary blobs is an
3459 // important use case for eager reclaim, and this special handling
3460 // may reduce needed headroom.
3461
3462 return is_typeArray_region(region) && is_remset_small(region);
3463 }
3464
3465 public:
3466 RegisterHumongousWithInCSetFastTestClosure()
3467 : _total_humongous(0),
3468 _candidate_humongous(0),
3469 _dcq(&JavaThread::dirty_card_queue_set()) {
3470 }
3471
3472 virtual bool doHeapRegion(HeapRegion* r) {
3473 if (!r->is_starts_humongous()) {
3474 return false;
3475 }
3476 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3477
3478 bool is_candidate = humongous_region_is_candidate(g1h, r);
3479 uint rindex = r->hrm_index();
3480 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3481 if (is_candidate) {
3482 _candidate_humongous++;
3483 g1h->register_humongous_region_with_cset(rindex);
3484 // Is_candidate already filters out humongous object with large remembered sets.
3485 // If we have a humongous object with a few remembered sets, we simply flush these
3486 // remembered set entries into the DCQS. That will result in automatic
3487 // re-evaluation of their remembered set entries during the following evacuation
3488 // phase.
3489 if (!r->rem_set()->is_empty()) {
3490 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3491 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3492 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3493 HeapRegionRemSetIterator hrrs(r->rem_set());
3494 size_t card_index;
3495 while (hrrs.has_next(card_index)) {
3496 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3497 // The remembered set might contain references to already freed
3498 // regions. Filter out such entries to avoid failing card table
3499 // verification.
3500 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3501 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3502 *card_ptr = CardTableModRefBS::dirty_card_val();
3503 _dcq.enqueue(card_ptr);
3504 }
3505 }
3506 }
3507 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3508 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3509 hrrs.n_yielded(), r->rem_set()->occupied());
3510 r->rem_set()->clear_locked();
3511 }
3512 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3513 }
3514 _total_humongous++;
3515
3516 return false;
3517 }
3518
3519 size_t total_humongous() const { return _total_humongous; }
3520 size_t candidate_humongous() const { return _candidate_humongous; }
3521
3522 void flush_rem_set_entries() { _dcq.flush(); }
3523 };
3524
3525 void G1CollectedHeap::register_humongous_regions_with_cset() {
3526 if (!G1EagerReclaimHumongousObjects) {
3527 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3528 return;
3529 }
3530 double time = os::elapsed_counter();
3531
3532 // Collect reclaim candidate information and register candidates with cset.
3533 RegisterHumongousWithInCSetFastTestClosure cl;
3534 heap_region_iterate(&cl);
3535
3536 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3537 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3538 cl.total_humongous(),
3539 cl.candidate_humongous());
3540 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3541
3542 // Finally flush all remembered set entries to re-check into the global DCQS.
3543 cl.flush_rem_set_entries();
3544 }
3545
3546 #ifdef ASSERT
3547 class VerifyCSetClosure: public HeapRegionClosure {
3548 public:
3549 bool doHeapRegion(HeapRegion* hr) {
3550 // Here we check that the CSet region's RSet is ready for parallel
3551 // iteration. The fields that we'll verify are only manipulated
3552 // when the region is part of a CSet and is collected. Afterwards,
3553 // we reset these fields when we clear the region's RSet (when the
3554 // region is freed) so they are ready when the region is
3555 // re-allocated. The only exception to this is if there's an
3556 // evacuation failure and instead of freeing the region we leave
3557 // it in the heap. In that case, we reset these fields during
3558 // evacuation failure handling.
3559 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3560
3561 // Here's a good place to add any other checks we'd like to
3562 // perform on CSet regions.
3563 return false;
3564 }
3565 };
3566 #endif // ASSERT
3567
3568 uint G1CollectedHeap::num_task_queues() const {
3569 return _task_queues->size();
3570 }
3571
3572 #if TASKQUEUE_STATS
3573 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3574 st->print_raw_cr("GC Task Stats");
3575 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3576 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3577 }
3578
3579 void G1CollectedHeap::print_taskqueue_stats() const {
3580 if (!develop_log_is_enabled(Trace, gc, task, stats)) {
3581 return;
3582 }
3583 LogHandle(gc, task, stats) log;
3584 ResourceMark rm;
3585 outputStream* st = log.trace_stream();
3586
3587 print_taskqueue_stats_hdr(st);
3588
3589 TaskQueueStats totals;
3590 const uint n = num_task_queues();
3591 for (uint i = 0; i < n; ++i) {
3592 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3593 totals += task_queue(i)->stats;
3594 }
3595 st->print_raw("tot "); totals.print(st); st->cr();
3596
3597 DEBUG_ONLY(totals.verify());
3598 }
3599
3600 void G1CollectedHeap::reset_taskqueue_stats() {
3601 const uint n = num_task_queues();
3602 for (uint i = 0; i < n; ++i) {
3603 task_queue(i)->stats.reset();
3604 }
3605 }
3606 #endif // TASKQUEUE_STATS
3607
3608 void G1CollectedHeap::log_gc_footer(double pause_time_counter) {
3609 if (evacuation_failed()) {
3610 log_info(gc)("To-space exhausted");
3611 }
3612
3613 double pause_time_sec = TimeHelper::counter_to_seconds(pause_time_counter);
3614 g1_policy()->print_phases(pause_time_sec);
3615
3616 g1_policy()->print_detailed_heap_transition();
3617 }
3618
3619
3620 void G1CollectedHeap::wait_for_root_region_scanning() {
3621 double scan_wait_start = os::elapsedTime();
3622 // We have to wait until the CM threads finish scanning the
3623 // root regions as it's the only way to ensure that all the
3624 // objects on them have been correctly scanned before we start
3625 // moving them during the GC.
3626 bool waited = _cm->root_regions()->wait_until_scan_finished();
3627 double wait_time_ms = 0.0;
3628 if (waited) {
3629 double scan_wait_end = os::elapsedTime();
3630 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3631 }
3632 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3633 }
3634
3635 bool
3636 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3637 assert_at_safepoint(true /* should_be_vm_thread */);
3638 guarantee(!is_gc_active(), "collection is not reentrant");
3639
3640 if (GC_locker::check_active_before_gc()) {
3641 return false;
3642 }
3643
3644 _gc_timer_stw->register_gc_start();
3645
3646 GCIdMark gc_id_mark;
3647 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3648
3649 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3650 ResourceMark rm;
3651
3652 wait_for_root_region_scanning();
3653
3654 print_heap_before_gc();
3655 trace_heap_before_gc(_gc_tracer_stw);
3656
3657 verify_region_sets_optional();
3658 verify_dirty_young_regions();
3659
3660 // This call will decide whether this pause is an initial-mark
3661 // pause. If it is, during_initial_mark_pause() will return true
3662 // for the duration of this pause.
3663 g1_policy()->decide_on_conc_mark_initiation();
3664
3665 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3666 assert(!collector_state()->during_initial_mark_pause() ||
3667 collector_state()->gcs_are_young(), "sanity");
3668
3669 // We also do not allow mixed GCs during marking.
3670 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3671
3672 // Record whether this pause is an initial mark. When the current
3673 // thread has completed its logging output and it's safe to signal
3674 // the CM thread, the flag's value in the policy has been reset.
3675 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3676
3677 // Inner scope for scope based logging, timers, and stats collection
3678 {
3679 EvacuationInfo evacuation_info;
3680
3681 if (collector_state()->during_initial_mark_pause()) {
3682 // We are about to start a marking cycle, so we increment the
3683 // full collection counter.
3684 increment_old_marking_cycles_started();
3685 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3686 }
3687
3688 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3689
3690 GCTraceCPUTime tcpu;
3691
3692 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3693 workers()->active_workers(),
3694 Threads::number_of_non_daemon_threads());
3695 workers()->set_active_workers(active_workers);
3696 FormatBuffer<> gc_string("Pause ");
3697 if (collector_state()->during_initial_mark_pause()) {
3698 gc_string.append("Initial Mark");
3699 } else if (collector_state()->gcs_are_young()) {
3700 gc_string.append("Young");
3701 } else {
3702 gc_string.append("Mixed");
3703 }
3704 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3705
3706 double pause_start_sec = os::elapsedTime();
3707 double pause_start_counter = os::elapsed_counter();
3708 g1_policy()->note_gc_start(active_workers);
3709
3710 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3711 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3712
3713 // If the secondary_free_list is not empty, append it to the
3714 // free_list. No need to wait for the cleanup operation to finish;
3715 // the region allocation code will check the secondary_free_list
3716 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3717 // set, skip this step so that the region allocation code has to
3718 // get entries from the secondary_free_list.
3719 if (!G1StressConcRegionFreeing) {
3720 append_secondary_free_list_if_not_empty_with_lock();
3721 }
3722
3723 assert(check_young_list_well_formed(), "young list should be well formed");
3724
3725 // Don't dynamically change the number of GC threads this early. A value of
3726 // 0 is used to indicate serial work. When parallel work is done,
3727 // it will be set.
3728
3729 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3730 IsGCActiveMark x;
3731
3732 gc_prologue(false);
3733 increment_total_collections(false /* full gc */);
3734 increment_gc_time_stamp();
3735
3736 verify_before_gc();
3737
3738 check_bitmaps("GC Start");
3739
3740 #if defined(COMPILER2) || INCLUDE_JVMCI
3741 DerivedPointerTable::clear();
3742 #endif
3743
3744 // Please see comment in g1CollectedHeap.hpp and
3745 // G1CollectedHeap::ref_processing_init() to see how
3746 // reference processing currently works in G1.
3747
3748 // Enable discovery in the STW reference processor
3749 if (g1_policy()->should_process_references()) {
3750 ref_processor_stw()->enable_discovery();
3751 } else {
3752 ref_processor_stw()->disable_discovery();
3753 }
3754
3755 {
3756 // We want to temporarily turn off discovery by the
3757 // CM ref processor, if necessary, and turn it back on
3758 // on again later if we do. Using a scoped
3759 // NoRefDiscovery object will do this.
3760 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3761
3762 // Forget the current alloc region (we might even choose it to be part
3763 // of the collection set!).
3764 _allocator->release_mutator_alloc_region();
3765
3766 // This timing is only used by the ergonomics to handle our pause target.
3767 // It is unclear why this should not include the full pause. We will
3768 // investigate this in CR 7178365.
3769 //
3770 // Preserving the old comment here if that helps the investigation:
3771 //
3772 // The elapsed time induced by the start time below deliberately elides
3773 // the possible verification above.
3774 double sample_start_time_sec = os::elapsedTime();
3775
3776 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3777
3778 if (collector_state()->during_initial_mark_pause()) {
3779 concurrent_mark()->checkpointRootsInitialPre();
3780 }
3781
3782 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3783 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3784
3785 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3786
3787 // Make sure the remembered sets are up to date. This needs to be
3788 // done before register_humongous_regions_with_cset(), because the
3789 // remembered sets are used there to choose eager reclaim candidates.
3790 // If the remembered sets are not up to date we might miss some
3791 // entries that need to be handled.
3792 g1_rem_set()->cleanupHRRS();
3793
3794 register_humongous_regions_with_cset();
3795
3796 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3797
3798 _cm->note_start_of_gc();
3799 // We call this after finalize_cset() to
3800 // ensure that the CSet has been finalized.
3801 _cm->verify_no_cset_oops();
3802
3803 if (_hr_printer.is_active()) {
3804 HeapRegion* hr = g1_policy()->collection_set();
3805 while (hr != NULL) {
3806 _hr_printer.cset(hr);
3807 hr = hr->next_in_collection_set();
3808 }
3809 }
3810
3811 #ifdef ASSERT
3812 VerifyCSetClosure cl;
3813 collection_set_iterate(&cl);
3814 #endif // ASSERT
3815
3816 // Initialize the GC alloc regions.
3817 _allocator->init_gc_alloc_regions(evacuation_info);
3818
3819 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3820 pre_evacuate_collection_set();
3821
3822 // Actually do the work...
3823 evacuate_collection_set(evacuation_info, &per_thread_states);
3824
3825 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3826
3827 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3828 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3829
3830 eagerly_reclaim_humongous_regions();
3831
3832 g1_policy()->clear_collection_set();
3833
3834 // Start a new incremental collection set for the next pause.
3835 g1_policy()->start_incremental_cset_building();
3836
3837 clear_cset_fast_test();
3838
3839 _young_list->reset_sampled_info();
3840
3841 // Don't check the whole heap at this point as the
3842 // GC alloc regions from this pause have been tagged
3843 // as survivors and moved on to the survivor list.
3844 // Survivor regions will fail the !is_young() check.
3845 assert(check_young_list_empty(false /* check_heap */),
3846 "young list should be empty");
3847
3848 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3849 _young_list->first_survivor_region(),
3850 _young_list->last_survivor_region());
3851
3852 _young_list->reset_auxilary_lists();
3853
3854 if (evacuation_failed()) {
3855 set_used(recalculate_used());
3856 if (_archive_allocator != NULL) {
3857 _archive_allocator->clear_used();
3858 }
3859 for (uint i = 0; i < ParallelGCThreads; i++) {
3860 if (_evacuation_failed_info_array[i].has_failed()) {
3861 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3862 }
3863 }
3864 } else {
3865 // The "used" of the the collection set have already been subtracted
3866 // when they were freed. Add in the bytes evacuated.
3867 increase_used(g1_policy()->bytes_copied_during_gc());
3868 }
3869
3870 if (collector_state()->during_initial_mark_pause()) {
3871 // We have to do this before we notify the CM threads that
3872 // they can start working to make sure that all the
3873 // appropriate initialization is done on the CM object.
3874 concurrent_mark()->checkpointRootsInitialPost();
3875 collector_state()->set_mark_in_progress(true);
3876 // Note that we don't actually trigger the CM thread at
3877 // this point. We do that later when we're sure that
3878 // the current thread has completed its logging output.
3879 }
3880
3881 allocate_dummy_regions();
3882
3883 _allocator->init_mutator_alloc_region();
3884
3885 {
3886 size_t expand_bytes = g1_policy()->expansion_amount();
3887 if (expand_bytes > 0) {
3888 size_t bytes_before = capacity();
3889 // No need for an ergo logging here,
3890 // expansion_amount() does this when it returns a value > 0.
3891 double expand_ms;
3892 if (!expand(expand_bytes, &expand_ms)) {
3893 // We failed to expand the heap. Cannot do anything about it.
3894 }
3895 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3896 }
3897 }
3898
3899 // We redo the verification but now wrt to the new CSet which
3900 // has just got initialized after the previous CSet was freed.
3901 _cm->verify_no_cset_oops();
3902 _cm->note_end_of_gc();
3903
3904 // This timing is only used by the ergonomics to handle our pause target.
3905 // It is unclear why this should not include the full pause. We will
3906 // investigate this in CR 7178365.
3907 double sample_end_time_sec = os::elapsedTime();
3908 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3909 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3910 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3911
3912 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3913 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3914
3915 MemoryService::track_memory_usage();
3916
3917 // In prepare_for_verify() below we'll need to scan the deferred
3918 // update buffers to bring the RSets up-to-date if
3919 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3920 // the update buffers we'll probably need to scan cards on the
3921 // regions we just allocated to (i.e., the GC alloc
3922 // regions). However, during the last GC we called
3923 // set_saved_mark() on all the GC alloc regions, so card
3924 // scanning might skip the [saved_mark_word()...top()] area of
3925 // those regions (i.e., the area we allocated objects into
3926 // during the last GC). But it shouldn't. Given that
3927 // saved_mark_word() is conditional on whether the GC time stamp
3928 // on the region is current or not, by incrementing the GC time
3929 // stamp here we invalidate all the GC time stamps on all the
3930 // regions and saved_mark_word() will simply return top() for
3931 // all the regions. This is a nicer way of ensuring this rather
3932 // than iterating over the regions and fixing them. In fact, the
3933 // GC time stamp increment here also ensures that
3934 // saved_mark_word() will return top() between pauses, i.e.,
3935 // during concurrent refinement. So we don't need the
3936 // is_gc_active() check to decided which top to use when
3937 // scanning cards (see CR 7039627).
3938 increment_gc_time_stamp();
3939
3940 verify_after_gc();
3941 check_bitmaps("GC End");
3942
3943 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3944 ref_processor_stw()->verify_no_references_recorded();
3945
3946 // CM reference discovery will be re-enabled if necessary.
3947 }
3948
3949 #ifdef TRACESPINNING
3950 ParallelTaskTerminator::print_termination_counts();
3951 #endif
3952
3953 gc_epilogue(false);
3954 }
3955
3956 // Print the remainder of the GC log output.
3957 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3958
3959 // It is not yet to safe to tell the concurrent mark to
3960 // start as we have some optional output below. We don't want the
3961 // output from the concurrent mark thread interfering with this
3962 // logging output either.
3963
3964 _hrm.verify_optional();
3965 verify_region_sets_optional();
3966
3967 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3968 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3969
3970 print_heap_after_gc();
3971 trace_heap_after_gc(_gc_tracer_stw);
3972
3973 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3974 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3975 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3976 // before any GC notifications are raised.
3977 g1mm()->update_sizes();
3978
3979 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3980 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3981 _gc_timer_stw->register_gc_end();
3982 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3983 }
3984 // It should now be safe to tell the concurrent mark thread to start
3985 // without its logging output interfering with the logging output
3986 // that came from the pause.
3987
3988 if (should_start_conc_mark) {
3989 // CAUTION: after the doConcurrentMark() call below,
3990 // the concurrent marking thread(s) could be running
3991 // concurrently with us. Make sure that anything after
3992 // this point does not assume that we are the only GC thread
3993 // running. Note: of course, the actual marking work will
3994 // not start until the safepoint itself is released in
3995 // SuspendibleThreadSet::desynchronize().
3996 doConcurrentMark();
3997 }
3998
3999 return true;
4000 }
4001
4002 void G1CollectedHeap::restore_preserved_marks() {
4003 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
4004 workers()->run_task(&rpm_task);
4005 }
4006
4007 void G1CollectedHeap::remove_self_forwarding_pointers() {
4008 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4009 workers()->run_task(&rsfp_task);
4010 }
4011
4012 void G1CollectedHeap::restore_after_evac_failure() {
4013 double remove_self_forwards_start = os::elapsedTime();
4014
4015 remove_self_forwarding_pointers();
4016 restore_preserved_marks();
4017
4018 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4019 }
4020
4021 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4022 if (!_evacuation_failed) {
4023 _evacuation_failed = true;
4024 }
4025
4026 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4027
4028 // We want to call the "for_promotion_failure" version only in the
4029 // case of a promotion failure.
4030 if (m->must_be_preserved_for_promotion_failure(obj)) {
4031 OopAndMarkOop elem(obj, m);
4032 _preserved_objs[worker_id].push(elem);
4033 }
4034 }
4035
4036 bool G1ParEvacuateFollowersClosure::offer_termination() {
4037 G1ParScanThreadState* const pss = par_scan_state();
4038 start_term_time();
4039 const bool res = terminator()->offer_termination();
4040 end_term_time();
4041 return res;
4042 }
4043
4044 void G1ParEvacuateFollowersClosure::do_void() {
4045 G1ParScanThreadState* const pss = par_scan_state();
4046 pss->trim_queue();
4047 do {
4048 pss->steal_and_trim_queue(queues());
4049 } while (!offer_termination());
4050 }
4051
4052 class G1ParTask : public AbstractGangTask {
4053 protected:
4054 G1CollectedHeap* _g1h;
4055 G1ParScanThreadStateSet* _pss;
4056 RefToScanQueueSet* _queues;
4057 G1RootProcessor* _root_processor;
4058 ParallelTaskTerminator _terminator;
4059 uint _n_workers;
4060
4061 public:
4062 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4063 : AbstractGangTask("G1 collection"),
4064 _g1h(g1h),
4065 _pss(per_thread_states),
4066 _queues(task_queues),
4067 _root_processor(root_processor),
4068 _terminator(n_workers, _queues),
4069 _n_workers(n_workers)
4070 {}
4071
4072 void work(uint worker_id) {
4073 if (worker_id >= _n_workers) return; // no work needed this round
4074
4075 double start_sec = os::elapsedTime();
4076 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4077
4078 {
4079 ResourceMark rm;
4080 HandleMark hm;
4081
4082 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4083
4084 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4085 pss->set_ref_processor(rp);
4086
4087 double start_strong_roots_sec = os::elapsedTime();
4088
4089 _root_processor->evacuate_roots(pss->closures(), worker_id);
4090
4091 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4092
4093 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4094 // treating the nmethods visited to act as roots for concurrent marking.
4095 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4096 // objects copied by the current evacuation.
4097 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4098 pss->closures()->weak_codeblobs(),
4099 worker_id);
4100
4101 _pss->add_cards_scanned(worker_id, cards_scanned);
4102
4103 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4104
4105 double term_sec = 0.0;
4106 size_t evac_term_attempts = 0;
4107 {
4108 double start = os::elapsedTime();
4109 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4110 evac.do_void();
4111
4112 evac_term_attempts = evac.term_attempts();
4113 term_sec = evac.term_time();
4114 double elapsed_sec = os::elapsedTime() - start;
4115 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4116 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4117 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4118 }
4119
4120 assert(pss->queue_is_empty(), "should be empty");
4121
4122 if (log_is_enabled(Debug, gc, task, stats)) {
4123 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4124 size_t lab_waste;
4125 size_t lab_undo_waste;
4126 pss->waste(lab_waste, lab_undo_waste);
4127 _g1h->print_termination_stats(worker_id,
4128 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4129 strong_roots_sec * 1000.0, /* strong roots time */
4130 term_sec * 1000.0, /* evac term time */
4131 evac_term_attempts, /* evac term attempts */
4132 lab_waste, /* alloc buffer waste */
4133 lab_undo_waste /* undo waste */
4134 );
4135 }
4136
4137 // Close the inner scope so that the ResourceMark and HandleMark
4138 // destructors are executed here and are included as part of the
4139 // "GC Worker Time".
4140 }
4141 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4142 }
4143 };
4144
4145 void G1CollectedHeap::print_termination_stats_hdr() {
4146 log_debug(gc, task, stats)("GC Termination Stats");
4147 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4148 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
4149 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4150 }
4151
4152 void G1CollectedHeap::print_termination_stats(uint worker_id,
4153 double elapsed_ms,
4154 double strong_roots_ms,
4155 double term_ms,
4156 size_t term_attempts,
4157 size_t alloc_buffer_waste,
4158 size_t undo_waste) const {
4159 log_debug(gc, task, stats)
4160 ("%3d %9.2f %9.2f %6.2f "
4161 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4162 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4163 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4164 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4165 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4166 alloc_buffer_waste * HeapWordSize / K,
4167 undo_waste * HeapWordSize / K);
4168 }
4169
4170 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4171 private:
4172 BoolObjectClosure* _is_alive;
4173 int _initial_string_table_size;
4174 int _initial_symbol_table_size;
4175
4176 bool _process_strings;
4177 int _strings_processed;
4178 int _strings_removed;
4179
4180 bool _process_symbols;
4181 int _symbols_processed;
4182 int _symbols_removed;
4183
4184 public:
4185 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4186 AbstractGangTask("String/Symbol Unlinking"),
4187 _is_alive(is_alive),
4188 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4189 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4190
4191 _initial_string_table_size = StringTable::the_table()->table_size();
4192 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4193 if (process_strings) {
4194 StringTable::clear_parallel_claimed_index();
4195 }
4196 if (process_symbols) {
4197 SymbolTable::clear_parallel_claimed_index();
4198 }
4199 }
4200
4201 ~G1StringSymbolTableUnlinkTask() {
4202 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4203 "claim value %d after unlink less than initial string table size %d",
4204 StringTable::parallel_claimed_index(), _initial_string_table_size);
4205 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4206 "claim value %d after unlink less than initial symbol table size %d",
4207 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4208
4209 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
4210 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4211 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4212 strings_processed(), strings_removed(),
4213 symbols_processed(), symbols_removed());
4214 }
4215
4216 void work(uint worker_id) {
4217 int strings_processed = 0;
4218 int strings_removed = 0;
4219 int symbols_processed = 0;
4220 int symbols_removed = 0;
4221 if (_process_strings) {
4222 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4223 Atomic::add(strings_processed, &_strings_processed);
4224 Atomic::add(strings_removed, &_strings_removed);
4225 }
4226 if (_process_symbols) {
4227 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4228 Atomic::add(symbols_processed, &_symbols_processed);
4229 Atomic::add(symbols_removed, &_symbols_removed);
4230 }
4231 }
4232
4233 size_t strings_processed() const { return (size_t)_strings_processed; }
4234 size_t strings_removed() const { return (size_t)_strings_removed; }
4235
4236 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4237 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4238 };
4239
4240 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4241 private:
4242 static Monitor* _lock;
4243
4244 BoolObjectClosure* const _is_alive;
4245 const bool _unloading_occurred;
4246 const uint _num_workers;
4247
4248 // Variables used to claim nmethods.
4249 nmethod* _first_nmethod;
4250 volatile nmethod* _claimed_nmethod;
4251
4252 // The list of nmethods that need to be processed by the second pass.
4253 volatile nmethod* _postponed_list;
4254 volatile uint _num_entered_barrier;
4255
4256 public:
4257 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4258 _is_alive(is_alive),
4259 _unloading_occurred(unloading_occurred),
4260 _num_workers(num_workers),
4261 _first_nmethod(NULL),
4262 _claimed_nmethod(NULL),
4263 _postponed_list(NULL),
4264 _num_entered_barrier(0)
4265 {
4266 nmethod::increase_unloading_clock();
4267 // Get first alive nmethod
4268 NMethodIterator iter = NMethodIterator();
4269 if(iter.next_alive()) {
4270 _first_nmethod = iter.method();
4271 }
4272 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4273 }
4274
4275 ~G1CodeCacheUnloadingTask() {
4276 CodeCache::verify_clean_inline_caches();
4277
4278 CodeCache::set_needs_cache_clean(false);
4279 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4280
4281 CodeCache::verify_icholder_relocations();
4282 }
4283
4284 private:
4285 void add_to_postponed_list(nmethod* nm) {
4286 nmethod* old;
4287 do {
4288 old = (nmethod*)_postponed_list;
4289 nm->set_unloading_next(old);
4290 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4291 }
4292
4293 void clean_nmethod(nmethod* nm) {
4294 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4295
4296 if (postponed) {
4297 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4298 add_to_postponed_list(nm);
4299 }
4300
4301 // Mark that this thread has been cleaned/unloaded.
4302 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4303 nm->set_unloading_clock(nmethod::global_unloading_clock());
4304 }
4305
4306 void clean_nmethod_postponed(nmethod* nm) {
4307 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4308 }
4309
4310 static const int MaxClaimNmethods = 16;
4311
4312 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4313 nmethod* first;
4314 NMethodIterator last;
4315
4316 do {
4317 *num_claimed_nmethods = 0;
4318
4319 first = (nmethod*)_claimed_nmethod;
4320 last = NMethodIterator(first);
4321
4322 if (first != NULL) {
4323
4324 for (int i = 0; i < MaxClaimNmethods; i++) {
4325 if (!last.next_alive()) {
4326 break;
4327 }
4328 claimed_nmethods[i] = last.method();
4329 (*num_claimed_nmethods)++;
4330 }
4331 }
4332
4333 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4334 }
4335
4336 nmethod* claim_postponed_nmethod() {
4337 nmethod* claim;
4338 nmethod* next;
4339
4340 do {
4341 claim = (nmethod*)_postponed_list;
4342 if (claim == NULL) {
4343 return NULL;
4344 }
4345
4346 next = claim->unloading_next();
4347
4348 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4349
4350 return claim;
4351 }
4352
4353 public:
4354 // Mark that we're done with the first pass of nmethod cleaning.
4355 void barrier_mark(uint worker_id) {
4356 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4357 _num_entered_barrier++;
4358 if (_num_entered_barrier == _num_workers) {
4359 ml.notify_all();
4360 }
4361 }
4362
4363 // See if we have to wait for the other workers to
4364 // finish their first-pass nmethod cleaning work.
4365 void barrier_wait(uint worker_id) {
4366 if (_num_entered_barrier < _num_workers) {
4367 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4368 while (_num_entered_barrier < _num_workers) {
4369 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4370 }
4371 }
4372 }
4373
4374 // Cleaning and unloading of nmethods. Some work has to be postponed
4375 // to the second pass, when we know which nmethods survive.
4376 void work_first_pass(uint worker_id) {
4377 // The first nmethods is claimed by the first worker.
4378 if (worker_id == 0 && _first_nmethod != NULL) {
4379 clean_nmethod(_first_nmethod);
4380 _first_nmethod = NULL;
4381 }
4382
4383 int num_claimed_nmethods;
4384 nmethod* claimed_nmethods[MaxClaimNmethods];
4385
4386 while (true) {
4387 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4388
4389 if (num_claimed_nmethods == 0) {
4390 break;
4391 }
4392
4393 for (int i = 0; i < num_claimed_nmethods; i++) {
4394 clean_nmethod(claimed_nmethods[i]);
4395 }
4396 }
4397 }
4398
4399 void work_second_pass(uint worker_id) {
4400 nmethod* nm;
4401 // Take care of postponed nmethods.
4402 while ((nm = claim_postponed_nmethod()) != NULL) {
4403 clean_nmethod_postponed(nm);
4404 }
4405 }
4406 };
4407
4408 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4409
4410 class G1KlassCleaningTask : public StackObj {
4411 BoolObjectClosure* _is_alive;
4412 volatile jint _clean_klass_tree_claimed;
4413 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4414
4415 public:
4416 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4417 _is_alive(is_alive),
4418 _clean_klass_tree_claimed(0),
4419 _klass_iterator() {
4420 }
4421
4422 private:
4423 bool claim_clean_klass_tree_task() {
4424 if (_clean_klass_tree_claimed) {
4425 return false;
4426 }
4427
4428 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4429 }
4430
4431 InstanceKlass* claim_next_klass() {
4432 Klass* klass;
4433 do {
4434 klass =_klass_iterator.next_klass();
4435 } while (klass != NULL && !klass->is_instance_klass());
4436
4437 // this can be null so don't call InstanceKlass::cast
4438 return static_cast<InstanceKlass*>(klass);
4439 }
4440
4441 public:
4442
4443 void clean_klass(InstanceKlass* ik) {
4444 ik->clean_weak_instanceklass_links(_is_alive);
4445 }
4446
4447 void work() {
4448 ResourceMark rm;
4449
4450 // One worker will clean the subklass/sibling klass tree.
4451 if (claim_clean_klass_tree_task()) {
4452 Klass::clean_subklass_tree(_is_alive);
4453 }
4454
4455 // All workers will help cleaning the classes,
4456 InstanceKlass* klass;
4457 while ((klass = claim_next_klass()) != NULL) {
4458 clean_klass(klass);
4459 }
4460 }
4461 };
4462
4463 // To minimize the remark pause times, the tasks below are done in parallel.
4464 class G1ParallelCleaningTask : public AbstractGangTask {
4465 private:
4466 G1StringSymbolTableUnlinkTask _string_symbol_task;
4467 G1CodeCacheUnloadingTask _code_cache_task;
4468 G1KlassCleaningTask _klass_cleaning_task;
4469
4470 public:
4471 // The constructor is run in the VMThread.
4472 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4473 AbstractGangTask("Parallel Cleaning"),
4474 _string_symbol_task(is_alive, process_strings, process_symbols),
4475 _code_cache_task(num_workers, is_alive, unloading_occurred),
4476 _klass_cleaning_task(is_alive) {
4477 }
4478
4479 // The parallel work done by all worker threads.
4480 void work(uint worker_id) {
4481 // Do first pass of code cache cleaning.
4482 _code_cache_task.work_first_pass(worker_id);
4483
4484 // Let the threads mark that the first pass is done.
4485 _code_cache_task.barrier_mark(worker_id);
4486
4487 // Clean the Strings and Symbols.
4488 _string_symbol_task.work(worker_id);
4489
4490 // Wait for all workers to finish the first code cache cleaning pass.
4491 _code_cache_task.barrier_wait(worker_id);
4492
4493 // Do the second code cache cleaning work, which realize on
4494 // the liveness information gathered during the first pass.
4495 _code_cache_task.work_second_pass(worker_id);
4496
4497 // Clean all klasses that were not unloaded.
4498 _klass_cleaning_task.work();
4499 }
4500 };
4501
4502
4503 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4504 bool process_strings,
4505 bool process_symbols,
4506 bool class_unloading_occurred) {
4507 uint n_workers = workers()->active_workers();
4508
4509 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4510 n_workers, class_unloading_occurred);
4511 workers()->run_task(&g1_unlink_task);
4512 }
4513
4514 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4515 bool process_strings, bool process_symbols) {
4516 {
4517 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4518 workers()->run_task(&g1_unlink_task);
4519 }
4520
4521 if (G1StringDedup::is_enabled()) {
4522 G1StringDedup::unlink(is_alive);
4523 }
4524 }
4525
4526 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4527 private:
4528 DirtyCardQueueSet* _queue;
4529 G1CollectedHeap* _g1h;
4530 public:
4531 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4532 _queue(queue), _g1h(g1h) { }
4533
4534 virtual void work(uint worker_id) {
4535 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4536 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4537
4538 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4539 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4540
4541 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4542 }
4543 };
4544
4545 void G1CollectedHeap::redirty_logged_cards() {
4546 double redirty_logged_cards_start = os::elapsedTime();
4547
4548 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4549 dirty_card_queue_set().reset_for_par_iteration();
4550 workers()->run_task(&redirty_task);
4551
4552 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4553 dcq.merge_bufferlists(&dirty_card_queue_set());
4554 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4555
4556 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4557 }
4558
4559 // Weak Reference Processing support
4560
4561 // An always "is_alive" closure that is used to preserve referents.
4562 // If the object is non-null then it's alive. Used in the preservation
4563 // of referent objects that are pointed to by reference objects
4564 // discovered by the CM ref processor.
4565 class G1AlwaysAliveClosure: public BoolObjectClosure {
4566 G1CollectedHeap* _g1;
4567 public:
4568 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4569 bool do_object_b(oop p) {
4570 if (p != NULL) {
4571 return true;
4572 }
4573 return false;
4574 }
4575 };
4576
4577 bool G1STWIsAliveClosure::do_object_b(oop p) {
4578 // An object is reachable if it is outside the collection set,
4579 // or is inside and copied.
4580 return !_g1->is_in_cset(p) || p->is_forwarded();
4581 }
4582
4583 // Non Copying Keep Alive closure
4584 class G1KeepAliveClosure: public OopClosure {
4585 G1CollectedHeap* _g1;
4586 public:
4587 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4588 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4589 void do_oop(oop* p) {
4590 oop obj = *p;
4591 assert(obj != NULL, "the caller should have filtered out NULL values");
4592
4593 const InCSetState cset_state = _g1->in_cset_state(obj);
4594 if (!cset_state.is_in_cset_or_humongous()) {
4595 return;
4596 }
4597 if (cset_state.is_in_cset()) {
4598 assert( obj->is_forwarded(), "invariant" );
4599 *p = obj->forwardee();
4600 } else {
4601 assert(!obj->is_forwarded(), "invariant" );
4602 assert(cset_state.is_humongous(),
4603 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4604 _g1->set_humongous_is_live(obj);
4605 }
4606 }
4607 };
4608
4609 // Copying Keep Alive closure - can be called from both
4610 // serial and parallel code as long as different worker
4611 // threads utilize different G1ParScanThreadState instances
4612 // and different queues.
4613
4614 class G1CopyingKeepAliveClosure: public OopClosure {
4615 G1CollectedHeap* _g1h;
4616 OopClosure* _copy_non_heap_obj_cl;
4617 G1ParScanThreadState* _par_scan_state;
4618
4619 public:
4620 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4621 OopClosure* non_heap_obj_cl,
4622 G1ParScanThreadState* pss):
4623 _g1h(g1h),
4624 _copy_non_heap_obj_cl(non_heap_obj_cl),
4625 _par_scan_state(pss)
4626 {}
4627
4628 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4629 virtual void do_oop( oop* p) { do_oop_work(p); }
4630
4631 template <class T> void do_oop_work(T* p) {
4632 oop obj = oopDesc::load_decode_heap_oop(p);
4633
4634 if (_g1h->is_in_cset_or_humongous(obj)) {
4635 // If the referent object has been forwarded (either copied
4636 // to a new location or to itself in the event of an
4637 // evacuation failure) then we need to update the reference
4638 // field and, if both reference and referent are in the G1
4639 // heap, update the RSet for the referent.
4640 //
4641 // If the referent has not been forwarded then we have to keep
4642 // it alive by policy. Therefore we have copy the referent.
4643 //
4644 // If the reference field is in the G1 heap then we can push
4645 // on the PSS queue. When the queue is drained (after each
4646 // phase of reference processing) the object and it's followers
4647 // will be copied, the reference field set to point to the
4648 // new location, and the RSet updated. Otherwise we need to
4649 // use the the non-heap or metadata closures directly to copy
4650 // the referent object and update the pointer, while avoiding
4651 // updating the RSet.
4652
4653 if (_g1h->is_in_g1_reserved(p)) {
4654 _par_scan_state->push_on_queue(p);
4655 } else {
4656 assert(!Metaspace::contains((const void*)p),
4657 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4658 _copy_non_heap_obj_cl->do_oop(p);
4659 }
4660 }
4661 }
4662 };
4663
4664 // Serial drain queue closure. Called as the 'complete_gc'
4665 // closure for each discovered list in some of the
4666 // reference processing phases.
4667
4668 class G1STWDrainQueueClosure: public VoidClosure {
4669 protected:
4670 G1CollectedHeap* _g1h;
4671 G1ParScanThreadState* _par_scan_state;
4672
4673 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4674
4675 public:
4676 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4677 _g1h(g1h),
4678 _par_scan_state(pss)
4679 { }
4680
4681 void do_void() {
4682 G1ParScanThreadState* const pss = par_scan_state();
4683 pss->trim_queue();
4684 }
4685 };
4686
4687 // Parallel Reference Processing closures
4688
4689 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4690 // processing during G1 evacuation pauses.
4691
4692 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4693 private:
4694 G1CollectedHeap* _g1h;
4695 G1ParScanThreadStateSet* _pss;
4696 RefToScanQueueSet* _queues;
4697 WorkGang* _workers;
4698 uint _active_workers;
4699
4700 public:
4701 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4702 G1ParScanThreadStateSet* per_thread_states,
4703 WorkGang* workers,
4704 RefToScanQueueSet *task_queues,
4705 uint n_workers) :
4706 _g1h(g1h),
4707 _pss(per_thread_states),
4708 _queues(task_queues),
4709 _workers(workers),
4710 _active_workers(n_workers)
4711 {
4712 assert(n_workers > 0, "shouldn't call this otherwise");
4713 }
4714
4715 // Executes the given task using concurrent marking worker threads.
4716 virtual void execute(ProcessTask& task);
4717 virtual void execute(EnqueueTask& task);
4718 };
4719
4720 // Gang task for possibly parallel reference processing
4721
4722 class G1STWRefProcTaskProxy: public AbstractGangTask {
4723 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4724 ProcessTask& _proc_task;
4725 G1CollectedHeap* _g1h;
4726 G1ParScanThreadStateSet* _pss;
4727 RefToScanQueueSet* _task_queues;
4728 ParallelTaskTerminator* _terminator;
4729
4730 public:
4731 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4732 G1CollectedHeap* g1h,
4733 G1ParScanThreadStateSet* per_thread_states,
4734 RefToScanQueueSet *task_queues,
4735 ParallelTaskTerminator* terminator) :
4736 AbstractGangTask("Process reference objects in parallel"),
4737 _proc_task(proc_task),
4738 _g1h(g1h),
4739 _pss(per_thread_states),
4740 _task_queues(task_queues),
4741 _terminator(terminator)
4742 {}
4743
4744 virtual void work(uint worker_id) {
4745 // The reference processing task executed by a single worker.
4746 ResourceMark rm;
4747 HandleMark hm;
4748
4749 G1STWIsAliveClosure is_alive(_g1h);
4750
4751 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4752 pss->set_ref_processor(NULL);
4753
4754 // Keep alive closure.
4755 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4756
4757 // Complete GC closure
4758 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4759
4760 // Call the reference processing task's work routine.
4761 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4762
4763 // Note we cannot assert that the refs array is empty here as not all
4764 // of the processing tasks (specifically phase2 - pp2_work) execute
4765 // the complete_gc closure (which ordinarily would drain the queue) so
4766 // the queue may not be empty.
4767 }
4768 };
4769
4770 // Driver routine for parallel reference processing.
4771 // Creates an instance of the ref processing gang
4772 // task and has the worker threads execute it.
4773 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4774 assert(_workers != NULL, "Need parallel worker threads.");
4775
4776 ParallelTaskTerminator terminator(_active_workers, _queues);
4777 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4778
4779 _workers->run_task(&proc_task_proxy);
4780 }
4781
4782 // Gang task for parallel reference enqueueing.
4783
4784 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4785 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4786 EnqueueTask& _enq_task;
4787
4788 public:
4789 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4790 AbstractGangTask("Enqueue reference objects in parallel"),
4791 _enq_task(enq_task)
4792 { }
4793
4794 virtual void work(uint worker_id) {
4795 _enq_task.work(worker_id);
4796 }
4797 };
4798
4799 // Driver routine for parallel reference enqueueing.
4800 // Creates an instance of the ref enqueueing gang
4801 // task and has the worker threads execute it.
4802
4803 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4804 assert(_workers != NULL, "Need parallel worker threads.");
4805
4806 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4807
4808 _workers->run_task(&enq_task_proxy);
4809 }
4810
4811 // End of weak reference support closures
4812
4813 // Abstract task used to preserve (i.e. copy) any referent objects
4814 // that are in the collection set and are pointed to by reference
4815 // objects discovered by the CM ref processor.
4816
4817 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4818 protected:
4819 G1CollectedHeap* _g1h;
4820 G1ParScanThreadStateSet* _pss;
4821 RefToScanQueueSet* _queues;
4822 ParallelTaskTerminator _terminator;
4823 uint _n_workers;
4824
4825 public:
4826 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4827 AbstractGangTask("ParPreserveCMReferents"),
4828 _g1h(g1h),
4829 _pss(per_thread_states),
4830 _queues(task_queues),
4831 _terminator(workers, _queues),
4832 _n_workers(workers)
4833 { }
4834
4835 void work(uint worker_id) {
4836 ResourceMark rm;
4837 HandleMark hm;
4838
4839 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4840 pss->set_ref_processor(NULL);
4841 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4842
4843 // Is alive closure
4844 G1AlwaysAliveClosure always_alive(_g1h);
4845
4846 // Copying keep alive closure. Applied to referent objects that need
4847 // to be copied.
4848 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4849
4850 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4851
4852 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4853 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4854
4855 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4856 // So this must be true - but assert just in case someone decides to
4857 // change the worker ids.
4858 assert(worker_id < limit, "sanity");
4859 assert(!rp->discovery_is_atomic(), "check this code");
4860
4861 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4862 for (uint idx = worker_id; idx < limit; idx += stride) {
4863 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4864
4865 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4866 while (iter.has_next()) {
4867 // Since discovery is not atomic for the CM ref processor, we
4868 // can see some null referent objects.
4869 iter.load_ptrs(DEBUG_ONLY(true));
4870 oop ref = iter.obj();
4871
4872 // This will filter nulls.
4873 if (iter.is_referent_alive()) {
4874 iter.make_referent_alive();
4875 }
4876 iter.move_to_next();
4877 }
4878 }
4879
4880 // Drain the queue - which may cause stealing
4881 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4882 drain_queue.do_void();
4883 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4884 assert(pss->queue_is_empty(), "should be");
4885 }
4886 };
4887
4888 void G1CollectedHeap::process_weak_jni_handles() {
4889 double ref_proc_start = os::elapsedTime();
4890
4891 G1STWIsAliveClosure is_alive(this);
4892 G1KeepAliveClosure keep_alive(this);
4893 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4894
4895 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4896 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4897 }
4898
4899 // Weak Reference processing during an evacuation pause (part 1).
4900 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4901 double ref_proc_start = os::elapsedTime();
4902
4903 ReferenceProcessor* rp = _ref_processor_stw;
4904 assert(rp->discovery_enabled(), "should have been enabled");
4905
4906 // Any reference objects, in the collection set, that were 'discovered'
4907 // by the CM ref processor should have already been copied (either by
4908 // applying the external root copy closure to the discovered lists, or
4909 // by following an RSet entry).
4910 //
4911 // But some of the referents, that are in the collection set, that these
4912 // reference objects point to may not have been copied: the STW ref
4913 // processor would have seen that the reference object had already
4914 // been 'discovered' and would have skipped discovering the reference,
4915 // but would not have treated the reference object as a regular oop.
4916 // As a result the copy closure would not have been applied to the
4917 // referent object.
4918 //
4919 // We need to explicitly copy these referent objects - the references
4920 // will be processed at the end of remarking.
4921 //
4922 // We also need to do this copying before we process the reference
4923 // objects discovered by the STW ref processor in case one of these
4924 // referents points to another object which is also referenced by an
4925 // object discovered by the STW ref processor.
4926
4927 uint no_of_gc_workers = workers()->active_workers();
4928
4929 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4930 per_thread_states,
4931 no_of_gc_workers,
4932 _task_queues);
4933
4934 workers()->run_task(&keep_cm_referents);
4935
4936 // Closure to test whether a referent is alive.
4937 G1STWIsAliveClosure is_alive(this);
4938
4939 // Even when parallel reference processing is enabled, the processing
4940 // of JNI refs is serial and performed serially by the current thread
4941 // rather than by a worker. The following PSS will be used for processing
4942 // JNI refs.
4943
4944 // Use only a single queue for this PSS.
4945 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4946 pss->set_ref_processor(NULL);
4947 assert(pss->queue_is_empty(), "pre-condition");
4948
4949 // Keep alive closure.
4950 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4951
4952 // Serial Complete GC closure
4953 G1STWDrainQueueClosure drain_queue(this, pss);
4954
4955 // Setup the soft refs policy...
4956 rp->setup_policy(false);
4957
4958 ReferenceProcessorStats stats;
4959 if (!rp->processing_is_mt()) {
4960 // Serial reference processing...
4961 stats = rp->process_discovered_references(&is_alive,
4962 &keep_alive,
4963 &drain_queue,
4964 NULL,
4965 _gc_timer_stw);
4966 } else {
4967 // Parallel reference processing
4968 assert(rp->num_q() == no_of_gc_workers, "sanity");
4969 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4970
4971 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4972 stats = rp->process_discovered_references(&is_alive,
4973 &keep_alive,
4974 &drain_queue,
4975 &par_task_executor,
4976 _gc_timer_stw);
4977 }
4978
4979 _gc_tracer_stw->report_gc_reference_stats(stats);
4980
4981 // We have completed copying any necessary live referent objects.
4982 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4983
4984 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4985 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4986 }
4987
4988 // Weak Reference processing during an evacuation pause (part 2).
4989 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4990 double ref_enq_start = os::elapsedTime();
4991
4992 ReferenceProcessor* rp = _ref_processor_stw;
4993 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4994
4995 // Now enqueue any remaining on the discovered lists on to
4996 // the pending list.
4997 if (!rp->processing_is_mt()) {
4998 // Serial reference processing...
4999 rp->enqueue_discovered_references();
5000 } else {
5001 // Parallel reference enqueueing
5002
5003 uint n_workers = workers()->active_workers();
5004
5005 assert(rp->num_q() == n_workers, "sanity");
5006 assert(n_workers <= rp->max_num_q(), "sanity");
5007
5008 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5009 rp->enqueue_discovered_references(&par_task_executor);
5010 }
5011
5012 rp->verify_no_references_recorded();
5013 assert(!rp->discovery_enabled(), "should have been disabled");
5014
5015 // FIXME
5016 // CM's reference processing also cleans up the string and symbol tables.
5017 // Should we do that here also? We could, but it is a serial operation
5018 // and could significantly increase the pause time.
5019
5020 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5021 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5022 }
5023
5024 void G1CollectedHeap::pre_evacuate_collection_set() {
5025 _expand_heap_after_alloc_failure = true;
5026 _evacuation_failed = false;
5027
5028 // Disable the hot card cache.
5029 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5030 hot_card_cache->reset_hot_cache_claimed_index();
5031 hot_card_cache->set_use_cache(false);
5032
5033 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5034 }
5035
5036 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5037 // Should G1EvacuationFailureALot be in effect for this GC?
5038 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5039
5040 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5041 double start_par_time_sec = os::elapsedTime();
5042 double end_par_time_sec;
5043
5044 {
5045 const uint n_workers = workers()->active_workers();
5046 G1RootProcessor root_processor(this, n_workers);
5047 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5048 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5049 if (collector_state()->during_initial_mark_pause()) {
5050 ClassLoaderDataGraph::clear_claimed_marks();
5051 }
5052
5053 print_termination_stats_hdr();
5054
5055 workers()->run_task(&g1_par_task);
5056 end_par_time_sec = os::elapsedTime();
5057
5058 // Closing the inner scope will execute the destructor
5059 // for the G1RootProcessor object. We record the current
5060 // elapsed time before closing the scope so that time
5061 // taken for the destructor is NOT included in the
5062 // reported parallel time.
5063 }
5064
5065 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5066
5067 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5068 phase_times->record_par_time(par_time_ms);
5069
5070 double code_root_fixup_time_ms =
5071 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5072 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5073 }
5074
5075 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5076 // Process any discovered reference objects - we have
5077 // to do this _before_ we retire the GC alloc regions
5078 // as we may have to copy some 'reachable' referent
5079 // objects (and their reachable sub-graphs) that were
5080 // not copied during the pause.
5081 if (g1_policy()->should_process_references()) {
5082 process_discovered_references(per_thread_states);
5083 } else {
5084 ref_processor_stw()->verify_no_references_recorded();
5085 process_weak_jni_handles();
5086 }
5087
5088 if (G1StringDedup::is_enabled()) {
5089 double fixup_start = os::elapsedTime();
5090
5091 G1STWIsAliveClosure is_alive(this);
5092 G1KeepAliveClosure keep_alive(this);
5093 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5094
5095 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5096 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5097 }
5098
5099 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5100
5101 if (evacuation_failed()) {
5102 restore_after_evac_failure();
5103
5104 // Reset the G1EvacuationFailureALot counters and flags
5105 // Note: the values are reset only when an actual
5106 // evacuation failure occurs.
5107 NOT_PRODUCT(reset_evacuation_should_fail();)
5108 }
5109
5110 // Enqueue any remaining references remaining on the STW
5111 // reference processor's discovered lists. We need to do
5112 // this after the card table is cleaned (and verified) as
5113 // the act of enqueueing entries on to the pending list
5114 // will log these updates (and dirty their associated
5115 // cards). We need these updates logged to update any
5116 // RSets.
5117 if (g1_policy()->should_process_references()) {
5118 enqueue_discovered_references(per_thread_states);
5119 } else {
5120 g1_policy()->phase_times()->record_ref_enq_time(0);
5121 }
5122
5123 _allocator->release_gc_alloc_regions(evacuation_info);
5124
5125 per_thread_states->flush();
5126
5127 record_obj_copy_mem_stats();
5128
5129 _survivor_evac_stats.adjust_desired_plab_sz();
5130 _old_evac_stats.adjust_desired_plab_sz();
5131
5132 // Reset and re-enable the hot card cache.
5133 // Note the counts for the cards in the regions in the
5134 // collection set are reset when the collection set is freed.
5135 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5136 hot_card_cache->reset_hot_cache();
5137 hot_card_cache->set_use_cache(true);
5138
5139 purge_code_root_memory();
5140
5141 redirty_logged_cards();
5142 #if defined(COMPILER2) || INCLUDE_JVMCI
5143 DerivedPointerTable::update_pointers();
5144 #endif
5145 }
5146
5147 void G1CollectedHeap::record_obj_copy_mem_stats() {
5148 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5149
5150 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5151 create_g1_evac_summary(&_old_evac_stats));
5152 }
5153
5154 void G1CollectedHeap::free_region(HeapRegion* hr,
5155 FreeRegionList* free_list,
5156 bool par,
5157 bool locked) {
5158 assert(!hr->is_free(), "the region should not be free");
5159 assert(!hr->is_empty(), "the region should not be empty");
5160 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5161 assert(free_list != NULL, "pre-condition");
5162
5163 if (G1VerifyBitmaps) {
5164 MemRegion mr(hr->bottom(), hr->end());
5165 concurrent_mark()->clearRangePrevBitmap(mr);
5166 }
5167
5168 // Clear the card counts for this region.
5169 // Note: we only need to do this if the region is not young
5170 // (since we don't refine cards in young regions).
5171 if (!hr->is_young()) {
5172 _cg1r->hot_card_cache()->reset_card_counts(hr);
5173 }
5174 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5175 free_list->add_ordered(hr);
5176 }
5177
5178 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5179 FreeRegionList* free_list,
5180 bool par) {
5181 assert(hr->is_humongous(), "this is only for humongous regions");
5182 assert(free_list != NULL, "pre-condition");
5183 hr->clear_humongous();
5184 free_region(hr, free_list, par);
5185 }
5186
5187 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
5188 const uint humongous_regions_removed) {
5189 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
5190 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5191 _old_set.bulk_remove(old_regions_removed);
5192 _humongous_set.bulk_remove(humongous_regions_removed);
5193 }
5194
5195 }
5196
5197 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5198 assert(list != NULL, "list can't be null");
5199 if (!list->is_empty()) {
5200 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5201 _hrm.insert_list_into_free_list(list);
5202 }
5203 }
5204
5205 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5206 decrease_used(bytes);
5207 }
5208
5209 class G1ParCleanupCTTask : public AbstractGangTask {
5210 G1SATBCardTableModRefBS* _ct_bs;
5211 G1CollectedHeap* _g1h;
5212 HeapRegion* volatile _su_head;
5213 public:
5214 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5215 G1CollectedHeap* g1h) :
5216 AbstractGangTask("G1 Par Cleanup CT Task"),
5217 _ct_bs(ct_bs), _g1h(g1h) { }
5218
5219 void work(uint worker_id) {
5220 HeapRegion* r;
5221 while (r = _g1h->pop_dirty_cards_region()) {
5222 clear_cards(r);
5223 }
5224 }
5225
5226 void clear_cards(HeapRegion* r) {
5227 // Cards of the survivors should have already been dirtied.
5228 if (!r->is_survivor()) {
5229 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5230 }
5231 }
5232 };
5233
5234 #ifndef PRODUCT
5235 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5236 G1CollectedHeap* _g1h;
5237 G1SATBCardTableModRefBS* _ct_bs;
5238 public:
5239 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5240 : _g1h(g1h), _ct_bs(ct_bs) { }
5241 virtual bool doHeapRegion(HeapRegion* r) {
5242 if (r->is_survivor()) {
5243 _g1h->verify_dirty_region(r);
5244 } else {
5245 _g1h->verify_not_dirty_region(r);
5246 }
5247 return false;
5248 }
5249 };
5250
5251 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5252 // All of the region should be clean.
5253 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5254 MemRegion mr(hr->bottom(), hr->end());
5255 ct_bs->verify_not_dirty_region(mr);
5256 }
5257
5258 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5259 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5260 // dirty allocated blocks as they allocate them. The thread that
5261 // retires each region and replaces it with a new one will do a
5262 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5263 // not dirty that area (one less thing to have to do while holding
5264 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5265 // is dirty.
5266 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5267 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5268 if (hr->is_young()) {
5269 ct_bs->verify_g1_young_region(mr);
5270 } else {
5271 ct_bs->verify_dirty_region(mr);
5272 }
5273 }
5274
5275 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5276 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5277 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5278 verify_dirty_region(hr);
5279 }
5280 }
5281
5282 void G1CollectedHeap::verify_dirty_young_regions() {
5283 verify_dirty_young_list(_young_list->first_region());
5284 }
5285
5286 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5287 HeapWord* tams, HeapWord* end) {
5288 guarantee(tams <= end,
5289 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5290 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5291 if (result < end) {
5292 log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5293 log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5294 return false;
5295 }
5296 return true;
5297 }
5298
5299 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5300 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5301 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5302
5303 HeapWord* bottom = hr->bottom();
5304 HeapWord* ptams = hr->prev_top_at_mark_start();
5305 HeapWord* ntams = hr->next_top_at_mark_start();
5306 HeapWord* end = hr->end();
5307
5308 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5309
5310 bool res_n = true;
5311 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5312 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5313 // if we happen to be in that state.
5314 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5315 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5316 }
5317 if (!res_p || !res_n) {
5318 log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5319 log_info(gc, verify)("#### Caller: %s", caller);
5320 return false;
5321 }
5322 return true;
5323 }
5324
5325 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5326 if (!G1VerifyBitmaps) return;
5327
5328 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5329 }
5330
5331 class G1VerifyBitmapClosure : public HeapRegionClosure {
5332 private:
5333 const char* _caller;
5334 G1CollectedHeap* _g1h;
5335 bool _failures;
5336
5337 public:
5338 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5339 _caller(caller), _g1h(g1h), _failures(false) { }
5340
5341 bool failures() { return _failures; }
5342
5343 virtual bool doHeapRegion(HeapRegion* hr) {
5344 bool result = _g1h->verify_bitmaps(_caller, hr);
5345 if (!result) {
5346 _failures = true;
5347 }
5348 return false;
5349 }
5350 };
5351
5352 void G1CollectedHeap::check_bitmaps(const char* caller) {
5353 if (!G1VerifyBitmaps) return;
5354
5355 G1VerifyBitmapClosure cl(caller, this);
5356 heap_region_iterate(&cl);
5357 guarantee(!cl.failures(), "bitmap verification");
5358 }
5359
5360 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5361 private:
5362 bool _failures;
5363 public:
5364 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5365
5366 virtual bool doHeapRegion(HeapRegion* hr) {
5367 uint i = hr->hrm_index();
5368 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5369 if (hr->is_humongous()) {
5370 if (hr->in_collection_set()) {
5371 log_info(gc, verify)("## humongous region %u in CSet", i);
5372 _failures = true;
5373 return true;
5374 }
5375 if (cset_state.is_in_cset()) {
5376 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for humongous region %u", cset_state.value(), i);
5377 _failures = true;
5378 return true;
5379 }
5380 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5381 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for continues humongous region %u", cset_state.value(), i);
5382 _failures = true;
5383 return true;
5384 }
5385 } else {
5386 if (cset_state.is_humongous()) {
5387 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for non-humongous region %u", cset_state.value(), i);
5388 _failures = true;
5389 return true;
5390 }
5391 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5392 log_info(gc, verify)("## in CSet %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5393 hr->in_collection_set(), cset_state.value(), i);
5394 _failures = true;
5395 return true;
5396 }
5397 if (cset_state.is_in_cset()) {
5398 if (hr->is_young() != (cset_state.is_young())) {
5399 log_info(gc, verify)("## is_young %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5400 hr->is_young(), cset_state.value(), i);
5401 _failures = true;
5402 return true;
5403 }
5404 if (hr->is_old() != (cset_state.is_old())) {
5405 log_info(gc, verify)("## is_old %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5406 hr->is_old(), cset_state.value(), i);
5407 _failures = true;
5408 return true;
5409 }
5410 }
5411 }
5412 return false;
5413 }
5414
5415 bool failures() const { return _failures; }
5416 };
5417
5418 bool G1CollectedHeap::check_cset_fast_test() {
5419 G1CheckCSetFastTableClosure cl;
5420 _hrm.iterate(&cl);
5421 return !cl.failures();
5422 }
5423 #endif // PRODUCT
5424
5425 void G1CollectedHeap::cleanUpCardTable() {
5426 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5427 double start = os::elapsedTime();
5428
5429 {
5430 // Iterate over the dirty cards region list.
5431 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5432
5433 workers()->run_task(&cleanup_task);
5434 #ifndef PRODUCT
5435 if (G1VerifyCTCleanup || VerifyAfterGC) {
5436 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5437 heap_region_iterate(&cleanup_verifier);
5438 }
5439 #endif
5440 }
5441
5442 double elapsed = os::elapsedTime() - start;
5443 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5444 }
5445
5446 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5447 size_t pre_used = 0;
5448 FreeRegionList local_free_list("Local List for CSet Freeing");
5449
5450 double young_time_ms = 0.0;
5451 double non_young_time_ms = 0.0;
5452
5453 // Since the collection set is a superset of the the young list,
5454 // all we need to do to clear the young list is clear its
5455 // head and length, and unlink any young regions in the code below
5456 _young_list->clear();
5457
5458 G1CollectorPolicy* policy = g1_policy();
5459
5460 double start_sec = os::elapsedTime();
5461 bool non_young = true;
5462
5463 HeapRegion* cur = cs_head;
5464 int age_bound = -1;
5465 size_t rs_lengths = 0;
5466
5467 while (cur != NULL) {
5468 assert(!is_on_master_free_list(cur), "sanity");
5469 if (non_young) {
5470 if (cur->is_young()) {
5471 double end_sec = os::elapsedTime();
5472 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5473 non_young_time_ms += elapsed_ms;
5474
5475 start_sec = os::elapsedTime();
5476 non_young = false;
5477 }
5478 } else {
5479 if (!cur->is_young()) {
5480 double end_sec = os::elapsedTime();
5481 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5482 young_time_ms += elapsed_ms;
5483
5484 start_sec = os::elapsedTime();
5485 non_young = true;
5486 }
5487 }
5488
5489 rs_lengths += cur->rem_set()->occupied_locked();
5490
5491 HeapRegion* next = cur->next_in_collection_set();
5492 assert(cur->in_collection_set(), "bad CS");
5493 cur->set_next_in_collection_set(NULL);
5494 clear_in_cset(cur);
5495
5496 if (cur->is_young()) {
5497 int index = cur->young_index_in_cset();
5498 assert(index != -1, "invariant");
5499 assert((uint) index < policy->young_cset_region_length(), "invariant");
5500 size_t words_survived = surviving_young_words[index];
5501 cur->record_surv_words_in_group(words_survived);
5502
5503 // At this point the we have 'popped' cur from the collection set
5504 // (linked via next_in_collection_set()) but it is still in the
5505 // young list (linked via next_young_region()). Clear the
5506 // _next_young_region field.
5507 cur->set_next_young_region(NULL);
5508 } else {
5509 int index = cur->young_index_in_cset();
5510 assert(index == -1, "invariant");
5511 }
5512
5513 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5514 (!cur->is_young() && cur->young_index_in_cset() == -1),
5515 "invariant" );
5516
5517 if (!cur->evacuation_failed()) {
5518 MemRegion used_mr = cur->used_region();
5519
5520 // And the region is empty.
5521 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5522 pre_used += cur->used();
5523 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5524 } else {
5525 cur->uninstall_surv_rate_group();
5526 if (cur->is_young()) {
5527 cur->set_young_index_in_cset(-1);
5528 }
5529 cur->set_evacuation_failed(false);
5530 // When moving a young gen region to old gen, we "allocate" that whole region
5531 // there. This is in addition to any already evacuated objects. Notify the
5532 // policy about that.
5533 // Old gen regions do not cause an additional allocation: both the objects
5534 // still in the region and the ones already moved are accounted for elsewhere.
5535 if (cur->is_young()) {
5536 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5537 }
5538 // The region is now considered to be old.
5539 cur->set_old();
5540 // Do some allocation statistics accounting. Regions that failed evacuation
5541 // are always made old, so there is no need to update anything in the young
5542 // gen statistics, but we need to update old gen statistics.
5543 size_t used_words = cur->marked_bytes() / HeapWordSize;
5544 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5545 _old_set.add(cur);
5546 evacuation_info.increment_collectionset_used_after(cur->used());
5547 }
5548 cur = next;
5549 }
5550
5551 evacuation_info.set_regions_freed(local_free_list.length());
5552 policy->record_max_rs_lengths(rs_lengths);
5553 policy->cset_regions_freed();
5554
5555 double end_sec = os::elapsedTime();
5556 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5557
5558 if (non_young) {
5559 non_young_time_ms += elapsed_ms;
5560 } else {
5561 young_time_ms += elapsed_ms;
5562 }
5563
5564 prepend_to_freelist(&local_free_list);
5565 decrement_summary_bytes(pre_used);
5566 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5567 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5568 }
5569
5570 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5571 private:
5572 FreeRegionList* _free_region_list;
5573 HeapRegionSet* _proxy_set;
5574 uint _humongous_regions_removed;
5575 size_t _freed_bytes;
5576 public:
5577
5578 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5579 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5580 }
5581
5582 virtual bool doHeapRegion(HeapRegion* r) {
5583 if (!r->is_starts_humongous()) {
5584 return false;
5585 }
5586
5587 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5588
5589 oop obj = (oop)r->bottom();
5590 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5591
5592 // The following checks whether the humongous object is live are sufficient.
5593 // The main additional check (in addition to having a reference from the roots
5594 // or the young gen) is whether the humongous object has a remembered set entry.
5595 //
5596 // A humongous object cannot be live if there is no remembered set for it
5597 // because:
5598 // - there can be no references from within humongous starts regions referencing
5599 // the object because we never allocate other objects into them.
5600 // (I.e. there are no intra-region references that may be missed by the
5601 // remembered set)
5602 // - as soon there is a remembered set entry to the humongous starts region
5603 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5604 // until the end of a concurrent mark.
5605 //
5606 // It is not required to check whether the object has been found dead by marking
5607 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5608 // all objects allocated during that time are considered live.
5609 // SATB marking is even more conservative than the remembered set.
5610 // So if at this point in the collection there is no remembered set entry,
5611 // nobody has a reference to it.
5612 // At the start of collection we flush all refinement logs, and remembered sets
5613 // are completely up-to-date wrt to references to the humongous object.
5614 //
5615 // Other implementation considerations:
5616 // - never consider object arrays at this time because they would pose
5617 // considerable effort for cleaning up the the remembered sets. This is
5618 // required because stale remembered sets might reference locations that
5619 // are currently allocated into.
5620 uint region_idx = r->hrm_index();
5621 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5622 !r->rem_set()->is_empty()) {
5623 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",
5624 region_idx,
5625 (size_t)obj->size() * HeapWordSize,
5626 p2i(r->bottom()),
5627 r->rem_set()->occupied(),
5628 r->rem_set()->strong_code_roots_list_length(),
5629 next_bitmap->isMarked(r->bottom()),
5630 g1h->is_humongous_reclaim_candidate(region_idx),
5631 obj->is_typeArray()
5632 );
5633 return false;
5634 }
5635
5636 guarantee(obj->is_typeArray(),
5637 "Only eagerly reclaiming type arrays is supported, but the object "
5638 PTR_FORMAT " is not.", p2i(r->bottom()));
5639
5640 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",
5641 region_idx,
5642 (size_t)obj->size() * HeapWordSize,
5643 p2i(r->bottom()),
5644 r->rem_set()->occupied(),
5645 r->rem_set()->strong_code_roots_list_length(),
5646 next_bitmap->isMarked(r->bottom()),
5647 g1h->is_humongous_reclaim_candidate(region_idx),
5648 obj->is_typeArray()
5649 );
5650
5651 // Need to clear mark bit of the humongous object if already set.
5652 if (next_bitmap->isMarked(r->bottom())) {
5653 next_bitmap->clear(r->bottom());
5654 }
5655 do {
5656 HeapRegion* next = g1h->next_region_in_humongous(r);
5657 _freed_bytes += r->used();
5658 r->set_containing_set(NULL);
5659 _humongous_regions_removed++;
5660 g1h->free_humongous_region(r, _free_region_list, false);
5661 r = next;
5662 } while (r != NULL);
5663
5664 return false;
5665 }
5666
5667 uint humongous_free_count() {
5668 return _humongous_regions_removed;
5669 }
5670
5671 size_t bytes_freed() const {
5672 return _freed_bytes;
5673 }
5674 };
5675
5676 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5677 assert_at_safepoint(true);
5678
5679 if (!G1EagerReclaimHumongousObjects ||
5680 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5681 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5682 return;
5683 }
5684
5685 double start_time = os::elapsedTime();
5686
5687 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5688
5689 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5690 heap_region_iterate(&cl);
5691
5692 remove_from_old_sets(0, cl.humongous_free_count());
5693
5694 G1HRPrinter* hrp = hr_printer();
5695 if (hrp->is_active()) {
5696 FreeRegionListIterator iter(&local_cleanup_list);
5697 while (iter.more_available()) {
5698 HeapRegion* hr = iter.get_next();
5699 hrp->cleanup(hr);
5700 }
5701 }
5702
5703 prepend_to_freelist(&local_cleanup_list);
5704 decrement_summary_bytes(cl.bytes_freed());
5705
5706 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5707 cl.humongous_free_count());
5708 }
5709
5710 // This routine is similar to the above but does not record
5711 // any policy statistics or update free lists; we are abandoning
5712 // the current incremental collection set in preparation of a
5713 // full collection. After the full GC we will start to build up
5714 // the incremental collection set again.
5715 // This is only called when we're doing a full collection
5716 // and is immediately followed by the tearing down of the young list.
5717
5718 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5719 HeapRegion* cur = cs_head;
5720
5721 while (cur != NULL) {
5722 HeapRegion* next = cur->next_in_collection_set();
5723 assert(cur->in_collection_set(), "bad CS");
5724 cur->set_next_in_collection_set(NULL);
5725 clear_in_cset(cur);
5726 cur->set_young_index_in_cset(-1);
5727 cur = next;
5728 }
5729 }
5730
5731 void G1CollectedHeap::set_free_regions_coming() {
5732 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5733
5734 assert(!free_regions_coming(), "pre-condition");
5735 _free_regions_coming = true;
5736 }
5737
5738 void G1CollectedHeap::reset_free_regions_coming() {
5739 assert(free_regions_coming(), "pre-condition");
5740
5741 {
5742 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5743 _free_regions_coming = false;
5744 SecondaryFreeList_lock->notify_all();
5745 }
5746
5747 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5748 }
5749
5750 void G1CollectedHeap::wait_while_free_regions_coming() {
5751 // Most of the time we won't have to wait, so let's do a quick test
5752 // first before we take the lock.
5753 if (!free_regions_coming()) {
5754 return;
5755 }
5756
5757 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5758
5759 {
5760 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5761 while (free_regions_coming()) {
5762 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5763 }
5764 }
5765
5766 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5767 }
5768
5769 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5770 return _allocator->is_retained_old_region(hr);
5771 }
5772
5773 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5774 _young_list->push_region(hr);
5775 }
5776
5777 class NoYoungRegionsClosure: public HeapRegionClosure {
5778 private:
5779 bool _success;
5780 public:
5781 NoYoungRegionsClosure() : _success(true) { }
5782 bool doHeapRegion(HeapRegion* r) {
5783 if (r->is_young()) {
5784 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5785 p2i(r->bottom()), p2i(r->end()));
5786 _success = false;
5787 }
5788 return false;
5789 }
5790 bool success() { return _success; }
5791 };
5792
5793 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5794 bool ret = _young_list->check_list_empty(check_sample);
5795
5796 if (check_heap) {
5797 NoYoungRegionsClosure closure;
5798 heap_region_iterate(&closure);
5799 ret = ret && closure.success();
5800 }
5801
5802 return ret;
5803 }
5804
5805 class TearDownRegionSetsClosure : public HeapRegionClosure {
5806 private:
5807 HeapRegionSet *_old_set;
5808
5809 public:
5810 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5811
5812 bool doHeapRegion(HeapRegion* r) {
5813 if (r->is_old()) {
5814 _old_set->remove(r);
5815 } else {
5816 // We ignore free regions, we'll empty the free list afterwards.
5817 // We ignore young regions, we'll empty the young list afterwards.
5818 // We ignore humongous regions, we're not tearing down the
5819 // humongous regions set.
5820 assert(r->is_free() || r->is_young() || r->is_humongous(),
5821 "it cannot be another type");
5822 }
5823 return false;
5824 }
5825
5826 ~TearDownRegionSetsClosure() {
5827 assert(_old_set->is_empty(), "post-condition");
5828 }
5829 };
5830
5831 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5832 assert_at_safepoint(true /* should_be_vm_thread */);
5833
5834 if (!free_list_only) {
5835 TearDownRegionSetsClosure cl(&_old_set);
5836 heap_region_iterate(&cl);
5837
5838 // Note that emptying the _young_list is postponed and instead done as
5839 // the first step when rebuilding the regions sets again. The reason for
5840 // this is that during a full GC string deduplication needs to know if
5841 // a collected region was young or old when the full GC was initiated.
5842 }
5843 _hrm.remove_all_free_regions();
5844 }
5845
5846 void G1CollectedHeap::increase_used(size_t bytes) {
5847 _summary_bytes_used += bytes;
5848 }
5849
5850 void G1CollectedHeap::decrease_used(size_t bytes) {
5851 assert(_summary_bytes_used >= bytes,
5852 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5853 _summary_bytes_used, bytes);
5854 _summary_bytes_used -= bytes;
5855 }
5856
5857 void G1CollectedHeap::set_used(size_t bytes) {
5858 _summary_bytes_used = bytes;
5859 }
5860
5861 class RebuildRegionSetsClosure : public HeapRegionClosure {
5862 private:
5863 bool _free_list_only;
5864 HeapRegionSet* _old_set;
5865 HeapRegionManager* _hrm;
5866 size_t _total_used;
5867
5868 public:
5869 RebuildRegionSetsClosure(bool free_list_only,
5870 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5871 _free_list_only(free_list_only),
5872 _old_set(old_set), _hrm(hrm), _total_used(0) {
5873 assert(_hrm->num_free_regions() == 0, "pre-condition");
5874 if (!free_list_only) {
5875 assert(_old_set->is_empty(), "pre-condition");
5876 }
5877 }
5878
5879 bool doHeapRegion(HeapRegion* r) {
5880 if (r->is_empty()) {
5881 // Add free regions to the free list
5882 r->set_free();
5883 r->set_allocation_context(AllocationContext::system());
5884 _hrm->insert_into_free_list(r);
5885 } else if (!_free_list_only) {
5886 assert(!r->is_young(), "we should not come across young regions");
5887
5888 if (r->is_humongous()) {
5889 // We ignore humongous regions. We left the humongous set unchanged.
5890 } else {
5891 // Objects that were compacted would have ended up on regions
5892 // that were previously old or free. Archive regions (which are
5893 // old) will not have been touched.
5894 assert(r->is_free() || r->is_old(), "invariant");
5895 // We now consider them old, so register as such. Leave
5896 // archive regions set that way, however, while still adding
5897 // them to the old set.
5898 if (!r->is_archive()) {
5899 r->set_old();
5900 }
5901 _old_set->add(r);
5902 }
5903 _total_used += r->used();
5904 }
5905
5906 return false;
5907 }
5908
5909 size_t total_used() {
5910 return _total_used;
5911 }
5912 };
5913
5914 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5915 assert_at_safepoint(true /* should_be_vm_thread */);
5916
5917 if (!free_list_only) {
5918 _young_list->empty_list();
5919 }
5920
5921 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5922 heap_region_iterate(&cl);
5923
5924 if (!free_list_only) {
5925 set_used(cl.total_used());
5926 if (_archive_allocator != NULL) {
5927 _archive_allocator->clear_used();
5928 }
5929 }
5930 assert(used_unlocked() == recalculate_used(),
5931 "inconsistent used_unlocked(), "
5932 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5933 used_unlocked(), recalculate_used());
5934 }
5935
5936 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5937 _refine_cte_cl->set_concurrent(concurrent);
5938 }
5939
5940 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5941 HeapRegion* hr = heap_region_containing(p);
5942 return hr->is_in(p);
5943 }
5944
5945 // Methods for the mutator alloc region
5946
5947 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5948 bool force) {
5949 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5950 assert(!force || g1_policy()->can_expand_young_list(),
5951 "if force is true we should be able to expand the young list");
5952 bool young_list_full = g1_policy()->is_young_list_full();
5953 if (force || !young_list_full) {
5954 HeapRegion* new_alloc_region = new_region(word_size,
5955 false /* is_old */,
5956 false /* do_expand */);
5957 if (new_alloc_region != NULL) {
5958 set_region_short_lived_locked(new_alloc_region);
5959 _hr_printer.alloc(new_alloc_region, young_list_full);
5960 check_bitmaps("Mutator Region Allocation", new_alloc_region);
5961 return new_alloc_region;
5962 }
5963 }
5964 return NULL;
5965 }
5966
5967 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5968 size_t allocated_bytes) {
5969 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5970 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5971
5972 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5973 increase_used(allocated_bytes);
5974 _hr_printer.retire(alloc_region);
5975 // We update the eden sizes here, when the region is retired,
5976 // instead of when it's allocated, since this is the point that its
5977 // used space has been recored in _summary_bytes_used.
5978 g1mm()->update_eden_size();
5979 }
5980
5981 // Methods for the GC alloc regions
5982
5983 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5984 uint count,
5985 InCSetState dest) {
5986 assert(FreeList_lock->owned_by_self(), "pre-condition");
5987
5988 if (count < g1_policy()->max_regions(dest)) {
5989 const bool is_survivor = (dest.is_young());
5990 HeapRegion* new_alloc_region = new_region(word_size,
5991 !is_survivor,
5992 true /* do_expand */);
5993 if (new_alloc_region != NULL) {
5994 // We really only need to do this for old regions given that we
5995 // should never scan survivors. But it doesn't hurt to do it
5996 // for survivors too.
5997 new_alloc_region->record_timestamp();
5998 if (is_survivor) {
5999 new_alloc_region->set_survivor();
6000 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6001 } else {
6002 new_alloc_region->set_old();
6003 check_bitmaps("Old Region Allocation", new_alloc_region);
6004 }
6005 _hr_printer.alloc(new_alloc_region);
6006 bool during_im = collector_state()->during_initial_mark_pause();
6007 new_alloc_region->note_start_of_copying(during_im);
6008 return new_alloc_region;
6009 }
6010 }
6011 return NULL;
6012 }
6013
6014 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6015 size_t allocated_bytes,
6016 InCSetState dest) {
6017 bool during_im = collector_state()->during_initial_mark_pause();
6018 alloc_region->note_end_of_copying(during_im);
6019 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6020 if (dest.is_young()) {
6021 young_list()->add_survivor_region(alloc_region);
6022 } else {
6023 _old_set.add(alloc_region);
6024 }
6025 _hr_printer.retire(alloc_region);
6026 }
6027
6028 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6029 bool expanded = false;
6030 uint index = _hrm.find_highest_free(&expanded);
6031
6032 if (index != G1_NO_HRM_INDEX) {
6033 if (expanded) {
6034 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6035 HeapRegion::GrainWords * HeapWordSize);
6036 }
6037 _hrm.allocate_free_regions_starting_at(index, 1);
6038 return region_at(index);
6039 }
6040 return NULL;
6041 }
6042
6043 // Heap region set verification
6044
6045 class VerifyRegionListsClosure : public HeapRegionClosure {
6046 private:
6047 HeapRegionSet* _old_set;
6048 HeapRegionSet* _humongous_set;
6049 HeapRegionManager* _hrm;
6050
6051 public:
6052 uint _old_count;
6053 uint _humongous_count;
6054 uint _free_count;
6055
6056 VerifyRegionListsClosure(HeapRegionSet* old_set,
6057 HeapRegionSet* humongous_set,
6058 HeapRegionManager* hrm) :
6059 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6060 _old_count(), _humongous_count(), _free_count(){ }
6061
6062 bool doHeapRegion(HeapRegion* hr) {
6063 if (hr->is_young()) {
6064 // TODO
6065 } else if (hr->is_humongous()) {
6066 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6067 _humongous_count++;
6068 } else if (hr->is_empty()) {
6069 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6070 _free_count++;
6071 } else if (hr->is_old()) {
6072 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6073 _old_count++;
6074 } else {
6075 // There are no other valid region types. Check for one invalid
6076 // one we can identify: pinned without old or humongous set.
6077 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6078 ShouldNotReachHere();
6079 }
6080 return false;
6081 }
6082
6083 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6084 guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);
6085 guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);
6086 guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);
6087 }
6088 };
6089
6090 void G1CollectedHeap::verify_region_sets() {
6091 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6092
6093 // First, check the explicit lists.
6094 _hrm.verify();
6095 {
6096 // Given that a concurrent operation might be adding regions to
6097 // the secondary free list we have to take the lock before
6098 // verifying it.
6099 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6100 _secondary_free_list.verify_list();
6101 }
6102
6103 // If a concurrent region freeing operation is in progress it will
6104 // be difficult to correctly attributed any free regions we come
6105 // across to the correct free list given that they might belong to
6106 // one of several (free_list, secondary_free_list, any local lists,
6107 // etc.). So, if that's the case we will skip the rest of the
6108 // verification operation. Alternatively, waiting for the concurrent
6109 // operation to complete will have a non-trivial effect on the GC's
6110 // operation (no concurrent operation will last longer than the
6111 // interval between two calls to verification) and it might hide
6112 // any issues that we would like to catch during testing.
6113 if (free_regions_coming()) {
6114 return;
6115 }
6116
6117 // Make sure we append the secondary_free_list on the free_list so
6118 // that all free regions we will come across can be safely
6119 // attributed to the free_list.
6120 append_secondary_free_list_if_not_empty_with_lock();
6121
6122 // Finally, make sure that the region accounting in the lists is
6123 // consistent with what we see in the heap.
6124
6125 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6126 heap_region_iterate(&cl);
6127 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6128 }
6129
6130 // Optimized nmethod scanning
6131
6132 class RegisterNMethodOopClosure: public OopClosure {
6133 G1CollectedHeap* _g1h;
6134 nmethod* _nm;
6135
6136 template <class T> void do_oop_work(T* p) {
6137 T heap_oop = oopDesc::load_heap_oop(p);
6138 if (!oopDesc::is_null(heap_oop)) {
6139 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6140 HeapRegion* hr = _g1h->heap_region_containing(obj);
6141 assert(!hr->is_continues_humongous(),
6142 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6143 " starting at " HR_FORMAT,
6144 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6145
6146 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6147 hr->add_strong_code_root_locked(_nm);
6148 }
6149 }
6150
6151 public:
6152 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6153 _g1h(g1h), _nm(nm) {}
6154
6155 void do_oop(oop* p) { do_oop_work(p); }
6156 void do_oop(narrowOop* p) { do_oop_work(p); }
6157 };
6158
6159 class UnregisterNMethodOopClosure: public OopClosure {
6160 G1CollectedHeap* _g1h;
6161 nmethod* _nm;
6162
6163 template <class T> void do_oop_work(T* p) {
6164 T heap_oop = oopDesc::load_heap_oop(p);
6165 if (!oopDesc::is_null(heap_oop)) {
6166 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6167 HeapRegion* hr = _g1h->heap_region_containing(obj);
6168 assert(!hr->is_continues_humongous(),
6169 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6170 " starting at " HR_FORMAT,
6171 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6172
6173 hr->remove_strong_code_root(_nm);
6174 }
6175 }
6176
6177 public:
6178 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6179 _g1h(g1h), _nm(nm) {}
6180
6181 void do_oop(oop* p) { do_oop_work(p); }
6182 void do_oop(narrowOop* p) { do_oop_work(p); }
6183 };
6184
6185 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6186 CollectedHeap::register_nmethod(nm);
6187
6188 guarantee(nm != NULL, "sanity");
6189 RegisterNMethodOopClosure reg_cl(this, nm);
6190 nm->oops_do(®_cl);
6191 }
6192
6193 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6194 CollectedHeap::unregister_nmethod(nm);
6195
6196 guarantee(nm != NULL, "sanity");
6197 UnregisterNMethodOopClosure reg_cl(this, nm);
6198 nm->oops_do(®_cl, true);
6199 }
6200
6201 void G1CollectedHeap::purge_code_root_memory() {
6202 double purge_start = os::elapsedTime();
6203 G1CodeRootSet::purge();
6204 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6205 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6206 }
6207
6208 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6209 G1CollectedHeap* _g1h;
6210
6211 public:
6212 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6213 _g1h(g1h) {}
6214
6215 void do_code_blob(CodeBlob* cb) {
6216 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6217 if (nm == NULL) {
6218 return;
6219 }
6220
6221 if (ScavengeRootsInCode) {
6222 _g1h->register_nmethod(nm);
6223 }
6224 }
6225 };
6226
6227 void G1CollectedHeap::rebuild_strong_code_roots() {
6228 RebuildStrongCodeRootClosure blob_cl(this);
6229 CodeCache::blobs_do(&blob_cl);
6230 }