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(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 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1793 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1794 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1795
1796 for (uint i = 0; i < n_queues; i++) {
1797 RefToScanQueue* q = new RefToScanQueue();
1798 q->initialize();
1799 _task_queues->register_queue(i, q);
1800 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1801 }
1802 clear_cset_start_regions();
1803
1804 // Initialize the G1EvacuationFailureALot counters and flags.
1805 NOT_PRODUCT(reset_evacuation_should_fail();)
1806
1807 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1808 }
1809
1810 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1811 size_t size,
1812 size_t translation_factor) {
1813 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1814 // Allocate a new reserved space, preferring to use large pages.
1815 ReservedSpace rs(size, preferred_page_size);
1816 G1RegionToSpaceMapper* result =
1817 G1RegionToSpaceMapper::create_mapper(rs,
1818 size,
1819 rs.alignment(),
1820 HeapRegion::GrainBytes,
1821 translation_factor,
1822 mtGC);
1823 if (TracePageSizes) {
1824 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1825 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1826 }
1827 return result;
1828 }
1829
1830 jint G1CollectedHeap::initialize() {
1831 CollectedHeap::pre_initialize();
1832 os::enable_vtime();
1833
1834 // Necessary to satisfy locking discipline assertions.
1835
1836 MutexLocker x(Heap_lock);
1837
1838 // While there are no constraints in the GC code that HeapWordSize
1839 // be any particular value, there are multiple other areas in the
1840 // system which believe this to be true (e.g. oop->object_size in some
1841 // cases incorrectly returns the size in wordSize units rather than
1842 // HeapWordSize).
1843 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1844
1845 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1846 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1847 size_t heap_alignment = collector_policy()->heap_alignment();
1848
1849 // Ensure that the sizes are properly aligned.
1850 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1851 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1852 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1853
1854 _refine_cte_cl = new RefineCardTableEntryClosure();
1855
1856 jint ecode = JNI_OK;
1857 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1858 if (_cg1r == NULL) {
1859 return ecode;
1860 }
1861
1862 // Reserve the maximum.
1863
1864 // When compressed oops are enabled, the preferred heap base
1865 // is calculated by subtracting the requested size from the
1866 // 32Gb boundary and using the result as the base address for
1867 // heap reservation. If the requested size is not aligned to
1868 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1869 // into the ReservedHeapSpace constructor) then the actual
1870 // base of the reserved heap may end up differing from the
1871 // address that was requested (i.e. the preferred heap base).
1872 // If this happens then we could end up using a non-optimal
1873 // compressed oops mode.
1874
1875 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1876 heap_alignment);
1877
1878 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1879
1880 // Create the barrier set for the entire reserved region.
1881 G1SATBCardTableLoggingModRefBS* bs
1882 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1883 bs->initialize();
1884 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1885 set_barrier_set(bs);
1886
1887 // Also create a G1 rem set.
1888 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1889
1890 // Carve out the G1 part of the heap.
1891 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1892 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1893 G1RegionToSpaceMapper* heap_storage =
1894 G1RegionToSpaceMapper::create_mapper(g1_rs,
1895 g1_rs.size(),
1896 page_size,
1897 HeapRegion::GrainBytes,
1898 1,
1899 mtJavaHeap);
1900 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1901 max_byte_size, page_size,
1902 heap_rs.base(),
1903 heap_rs.size());
1904 heap_storage->set_mapping_changed_listener(&_listener);
1905
1906 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1907 G1RegionToSpaceMapper* bot_storage =
1908 create_aux_memory_mapper("Block offset table",
1909 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1910 G1BlockOffsetTable::heap_map_factor());
1911
1912 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1913 G1RegionToSpaceMapper* cardtable_storage =
1914 create_aux_memory_mapper("Card table",
1915 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1916 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1917
1918 G1RegionToSpaceMapper* card_counts_storage =
1919 create_aux_memory_mapper("Card counts table",
1920 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1921 G1CardCounts::heap_map_factor());
1922
1923 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1924 G1RegionToSpaceMapper* prev_bitmap_storage =
1925 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1926 G1RegionToSpaceMapper* next_bitmap_storage =
1927 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1928
1929 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1930 g1_barrier_set()->initialize(cardtable_storage);
1931 // Do later initialization work for concurrent refinement.
1932 _cg1r->init(card_counts_storage);
1933
1934 // 6843694 - ensure that the maximum region index can fit
1935 // in the remembered set structures.
1936 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1937 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1938
1939 G1RemSet::initialize(max_regions());
1940
1941 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1942 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1943 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1944 "too many cards per region");
1945
1946 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1947
1948 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1949
1950 {
1951 HeapWord* start = _hrm.reserved().start();
1952 HeapWord* end = _hrm.reserved().end();
1953 size_t granularity = HeapRegion::GrainBytes;
1954
1955 _in_cset_fast_test.initialize(start, end, granularity);
1956 _humongous_reclaim_candidates.initialize(start, end, granularity);
1957 }
1958
1959 // Create the ConcurrentMark data structure and thread.
1960 // (Must do this late, so that "max_regions" is defined.)
1961 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1962 if (_cm == NULL || !_cm->completed_initialization()) {
1963 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1964 return JNI_ENOMEM;
1965 }
1966 _cmThread = _cm->cmThread();
1967
1968 // Now expand into the initial heap size.
1969 if (!expand(init_byte_size)) {
1970 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1971 return JNI_ENOMEM;
1972 }
1973
1974 // Perform any initialization actions delegated to the policy.
1975 g1_policy()->init();
1976
1977 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1978 SATB_Q_FL_lock,
1979 G1SATBProcessCompletedThreshold,
1980 Shared_SATB_Q_lock);
1981
1982 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1983 DirtyCardQ_CBL_mon,
1984 DirtyCardQ_FL_lock,
1985 concurrent_g1_refine()->yellow_zone(),
1986 concurrent_g1_refine()->red_zone(),
1987 Shared_DirtyCardQ_lock);
1988
1989 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1990 DirtyCardQ_CBL_mon,
1991 DirtyCardQ_FL_lock,
1992 -1, // never trigger processing
1993 -1, // no limit on length
1994 Shared_DirtyCardQ_lock,
1995 &JavaThread::dirty_card_queue_set());
1996
1997 // Here we allocate the dummy HeapRegion that is required by the
1998 // G1AllocRegion class.
1999 HeapRegion* dummy_region = _hrm.get_dummy_region();
2000
2001 // We'll re-use the same region whether the alloc region will
2002 // require BOT updates or not and, if it doesn't, then a non-young
2003 // region will complain that it cannot support allocations without
2004 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2005 dummy_region->set_eden();
2006 // Make sure it's full.
2007 dummy_region->set_top(dummy_region->end());
2008 G1AllocRegion::setup(this, dummy_region);
2009
2010 _allocator->init_mutator_alloc_region();
2011
2012 // Do create of the monitoring and management support so that
2013 // values in the heap have been properly initialized.
2014 _g1mm = new G1MonitoringSupport(this);
2015
2016 G1StringDedup::initialize();
2017
2018 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2019 for (uint i = 0; i < ParallelGCThreads; i++) {
2020 new (&_preserved_objs[i]) OopAndMarkOopStack();
2021 }
2022
2023 return JNI_OK;
2024 }
2025
2026 void G1CollectedHeap::stop() {
2027 // Stop all concurrent threads. We do this to make sure these threads
2028 // do not continue to execute and access resources (e.g. logging)
2029 // that are destroyed during shutdown.
2030 _cg1r->stop();
2031 _cmThread->stop();
2032 if (G1StringDedup::is_enabled()) {
2033 G1StringDedup::stop();
2034 }
2035 }
2036
2037 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2038 return HeapRegion::max_region_size();
2039 }
2040
2041 void G1CollectedHeap::post_initialize() {
2042 CollectedHeap::post_initialize();
2043 ref_processing_init();
2044 }
2045
2046 void G1CollectedHeap::ref_processing_init() {
2047 // Reference processing in G1 currently works as follows:
2048 //
2049 // * There are two reference processor instances. One is
2050 // used to record and process discovered references
2051 // during concurrent marking; the other is used to
2052 // record and process references during STW pauses
2053 // (both full and incremental).
2054 // * Both ref processors need to 'span' the entire heap as
2055 // the regions in the collection set may be dotted around.
2056 //
2057 // * For the concurrent marking ref processor:
2058 // * Reference discovery is enabled at initial marking.
2059 // * Reference discovery is disabled and the discovered
2060 // references processed etc during remarking.
2061 // * Reference discovery is MT (see below).
2062 // * Reference discovery requires a barrier (see below).
2063 // * Reference processing may or may not be MT
2064 // (depending on the value of ParallelRefProcEnabled
2065 // and ParallelGCThreads).
2066 // * A full GC disables reference discovery by the CM
2067 // ref processor and abandons any entries on it's
2068 // discovered lists.
2069 //
2070 // * For the STW processor:
2071 // * Non MT discovery is enabled at the start of a full GC.
2072 // * Processing and enqueueing during a full GC is non-MT.
2073 // * During a full GC, references are processed after marking.
2074 //
2075 // * Discovery (may or may not be MT) is enabled at the start
2076 // of an incremental evacuation pause.
2077 // * References are processed near the end of a STW evacuation pause.
2078 // * For both types of GC:
2079 // * Discovery is atomic - i.e. not concurrent.
2080 // * Reference discovery will not need a barrier.
2081
2082 MemRegion mr = reserved_region();
2083
2084 // Concurrent Mark ref processor
2085 _ref_processor_cm =
2086 new ReferenceProcessor(mr, // span
2087 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2088 // mt processing
2089 ParallelGCThreads,
2090 // degree of mt processing
2091 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2092 // mt discovery
2093 MAX2(ParallelGCThreads, ConcGCThreads),
2094 // degree of mt discovery
2095 false,
2096 // Reference discovery is not atomic
2097 &_is_alive_closure_cm);
2098 // is alive closure
2099 // (for efficiency/performance)
2100
2101 // STW ref processor
2102 _ref_processor_stw =
2103 new ReferenceProcessor(mr, // span
2104 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2105 // mt processing
2106 ParallelGCThreads,
2107 // degree of mt processing
2108 (ParallelGCThreads > 1),
2109 // mt discovery
2110 ParallelGCThreads,
2111 // degree of mt discovery
2112 true,
2113 // Reference discovery is atomic
2114 &_is_alive_closure_stw);
2115 // is alive closure
2116 // (for efficiency/performance)
2117 }
2118
2119 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2120 return g1_policy();
2121 }
2122
2123 size_t G1CollectedHeap::capacity() const {
2124 return _hrm.length() * HeapRegion::GrainBytes;
2125 }
2126
2127 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2128 hr->reset_gc_time_stamp();
2129 }
2130
2131 #ifndef PRODUCT
2132
2133 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2134 private:
2135 unsigned _gc_time_stamp;
2136 bool _failures;
2137
2138 public:
2139 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2140 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2141
2142 virtual bool doHeapRegion(HeapRegion* hr) {
2143 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2144 if (_gc_time_stamp != region_gc_time_stamp) {
2145 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2146 region_gc_time_stamp, _gc_time_stamp);
2147 _failures = true;
2148 }
2149 return false;
2150 }
2151
2152 bool failures() { return _failures; }
2153 };
2154
2155 void G1CollectedHeap::check_gc_time_stamps() {
2156 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2157 heap_region_iterate(&cl);
2158 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2159 }
2160 #endif // PRODUCT
2161
2162 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2163 _cg1r->hot_card_cache()->drain(cl, worker_i);
2164 }
2165
2166 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2167 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2168 size_t n_completed_buffers = 0;
2169 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2170 n_completed_buffers++;
2171 }
2172 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2173 dcqs.clear_n_completed_buffers();
2174 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2175 }
2176
2177 // Computes the sum of the storage used by the various regions.
2178 size_t G1CollectedHeap::used() const {
2179 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2180 if (_archive_allocator != NULL) {
2181 result += _archive_allocator->used();
2182 }
2183 return result;
2184 }
2185
2186 size_t G1CollectedHeap::used_unlocked() const {
2187 return _summary_bytes_used;
2188 }
2189
2190 class SumUsedClosure: public HeapRegionClosure {
2191 size_t _used;
2192 public:
2193 SumUsedClosure() : _used(0) {}
2194 bool doHeapRegion(HeapRegion* r) {
2195 _used += r->used();
2196 return false;
2197 }
2198 size_t result() { return _used; }
2199 };
2200
2201 size_t G1CollectedHeap::recalculate_used() const {
2202 double recalculate_used_start = os::elapsedTime();
2203
2204 SumUsedClosure blk;
2205 heap_region_iterate(&blk);
2206
2207 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2208 return blk.result();
2209 }
2210
2211 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2212 switch (cause) {
2213 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2214 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2215 case GCCause::_update_allocation_context_stats_inc: return true;
2216 case GCCause::_wb_conc_mark: return true;
2217 default : return false;
2218 }
2219 }
2220
2221 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2222 switch (cause) {
2223 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2224 case GCCause::_g1_humongous_allocation: return true;
2225 default: return is_user_requested_concurrent_full_gc(cause);
2226 }
2227 }
2228
2229 #ifndef PRODUCT
2230 void G1CollectedHeap::allocate_dummy_regions() {
2231 // Let's fill up most of the region
2232 size_t word_size = HeapRegion::GrainWords - 1024;
2233 // And as a result the region we'll allocate will be humongous.
2234 guarantee(is_humongous(word_size), "sanity");
2235
2236 // _filler_array_max_size is set to humongous object threshold
2237 // but temporarily change it to use CollectedHeap::fill_with_object().
2238 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2239
2240 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2241 // Let's use the existing mechanism for the allocation
2242 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2243 AllocationContext::system());
2244 if (dummy_obj != NULL) {
2245 MemRegion mr(dummy_obj, word_size);
2246 CollectedHeap::fill_with_object(mr);
2247 } else {
2248 // If we can't allocate once, we probably cannot allocate
2249 // again. Let's get out of the loop.
2250 break;
2251 }
2252 }
2253 }
2254 #endif // !PRODUCT
2255
2256 void G1CollectedHeap::increment_old_marking_cycles_started() {
2257 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2258 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2259 "Wrong marking cycle count (started: %d, completed: %d)",
2260 _old_marking_cycles_started, _old_marking_cycles_completed);
2261
2262 _old_marking_cycles_started++;
2263 }
2264
2265 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2266 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2267
2268 // We assume that if concurrent == true, then the caller is a
2269 // concurrent thread that was joined the Suspendible Thread
2270 // Set. If there's ever a cheap way to check this, we should add an
2271 // assert here.
2272
2273 // Given that this method is called at the end of a Full GC or of a
2274 // concurrent cycle, and those can be nested (i.e., a Full GC can
2275 // interrupt a concurrent cycle), the number of full collections
2276 // completed should be either one (in the case where there was no
2277 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2278 // behind the number of full collections started.
2279
2280 // This is the case for the inner caller, i.e. a Full GC.
2281 assert(concurrent ||
2282 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2283 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2284 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2285 "is inconsistent with _old_marking_cycles_completed = %u",
2286 _old_marking_cycles_started, _old_marking_cycles_completed);
2287
2288 // This is the case for the outer caller, i.e. the concurrent cycle.
2289 assert(!concurrent ||
2290 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2291 "for outer caller (concurrent cycle): "
2292 "_old_marking_cycles_started = %u "
2293 "is inconsistent with _old_marking_cycles_completed = %u",
2294 _old_marking_cycles_started, _old_marking_cycles_completed);
2295
2296 _old_marking_cycles_completed += 1;
2297
2298 // We need to clear the "in_progress" flag in the CM thread before
2299 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2300 // is set) so that if a waiter requests another System.gc() it doesn't
2301 // incorrectly see that a marking cycle is still in progress.
2302 if (concurrent) {
2303 _cmThread->set_idle();
2304 }
2305
2306 // This notify_all() will ensure that a thread that called
2307 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2308 // and it's waiting for a full GC to finish will be woken up. It is
2309 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2310 FullGCCount_lock->notify_all();
2311 }
2312
2313 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2314 GCIdMarkAndRestore conc_gc_id_mark;
2315 collector_state()->set_concurrent_cycle_started(true);
2316 _gc_timer_cm->register_gc_start(start_time);
2317
2318 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2319 trace_heap_before_gc(_gc_tracer_cm);
2320 _cmThread->set_gc_id(GCId::current());
2321 }
2322
2323 void G1CollectedHeap::register_concurrent_cycle_end() {
2324 if (collector_state()->concurrent_cycle_started()) {
2325 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2326 if (_cm->has_aborted()) {
2327 _gc_tracer_cm->report_concurrent_mode_failure();
2328 }
2329
2330 _gc_timer_cm->register_gc_end();
2331 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2332
2333 // Clear state variables to prepare for the next concurrent cycle.
2334 collector_state()->set_concurrent_cycle_started(false);
2335 _heap_summary_sent = false;
2336 }
2337 }
2338
2339 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2340 if (collector_state()->concurrent_cycle_started()) {
2341 // This function can be called when:
2342 // the cleanup pause is run
2343 // the concurrent cycle is aborted before the cleanup pause.
2344 // the concurrent cycle is aborted after the cleanup pause,
2345 // but before the concurrent cycle end has been registered.
2346 // Make sure that we only send the heap information once.
2347 if (!_heap_summary_sent) {
2348 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2349 trace_heap_after_gc(_gc_tracer_cm);
2350 _heap_summary_sent = true;
2351 }
2352 }
2353 }
2354
2355 void G1CollectedHeap::collect(GCCause::Cause cause) {
2356 assert_heap_not_locked();
2357
2358 uint gc_count_before;
2359 uint old_marking_count_before;
2360 uint full_gc_count_before;
2361 bool retry_gc;
2362
2363 do {
2364 retry_gc = false;
2365
2366 {
2367 MutexLocker ml(Heap_lock);
2368
2369 // Read the GC count while holding the Heap_lock
2370 gc_count_before = total_collections();
2371 full_gc_count_before = total_full_collections();
2372 old_marking_count_before = _old_marking_cycles_started;
2373 }
2374
2375 if (should_do_concurrent_full_gc(cause)) {
2376 // Schedule an initial-mark evacuation pause that will start a
2377 // concurrent cycle. We're setting word_size to 0 which means that
2378 // we are not requesting a post-GC allocation.
2379 VM_G1IncCollectionPause op(gc_count_before,
2380 0, /* word_size */
2381 true, /* should_initiate_conc_mark */
2382 g1_policy()->max_pause_time_ms(),
2383 cause);
2384 op.set_allocation_context(AllocationContext::current());
2385
2386 VMThread::execute(&op);
2387 if (!op.pause_succeeded()) {
2388 if (old_marking_count_before == _old_marking_cycles_started) {
2389 retry_gc = op.should_retry_gc();
2390 } else {
2391 // A Full GC happened while we were trying to schedule the
2392 // initial-mark GC. No point in starting a new cycle given
2393 // that the whole heap was collected anyway.
2394 }
2395
2396 if (retry_gc) {
2397 if (GC_locker::is_active_and_needs_gc()) {
2398 GC_locker::stall_until_clear();
2399 }
2400 }
2401 }
2402 } else {
2403 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2404 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2405
2406 // Schedule a standard evacuation pause. We're setting word_size
2407 // to 0 which means that we are not requesting a post-GC allocation.
2408 VM_G1IncCollectionPause op(gc_count_before,
2409 0, /* word_size */
2410 false, /* should_initiate_conc_mark */
2411 g1_policy()->max_pause_time_ms(),
2412 cause);
2413 VMThread::execute(&op);
2414 } else {
2415 // Schedule a Full GC.
2416 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2417 VMThread::execute(&op);
2418 }
2419 }
2420 } while (retry_gc);
2421 }
2422
2423 bool G1CollectedHeap::is_in(const void* p) const {
2424 if (_hrm.reserved().contains(p)) {
2425 // Given that we know that p is in the reserved space,
2426 // heap_region_containing() should successfully
2427 // return the containing region.
2428 HeapRegion* hr = heap_region_containing(p);
2429 return hr->is_in(p);
2430 } else {
2431 return false;
2432 }
2433 }
2434
2435 #ifdef ASSERT
2436 bool G1CollectedHeap::is_in_exact(const void* p) const {
2437 bool contains = reserved_region().contains(p);
2438 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2439 if (contains && available) {
2440 return true;
2441 } else {
2442 return false;
2443 }
2444 }
2445 #endif
2446
2447 bool G1CollectedHeap::obj_in_cs(oop obj) {
2448 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2449 return r != NULL && r->in_collection_set();
2450 }
2451
2452 // Iteration functions.
2453
2454 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2455
2456 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2457 ExtendedOopClosure* _cl;
2458 public:
2459 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2460 bool doHeapRegion(HeapRegion* r) {
2461 if (!r->is_continues_humongous()) {
2462 r->oop_iterate(_cl);
2463 }
2464 return false;
2465 }
2466 };
2467
2468 // Iterates an ObjectClosure over all objects within a HeapRegion.
2469
2470 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2471 ObjectClosure* _cl;
2472 public:
2473 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2474 bool doHeapRegion(HeapRegion* r) {
2475 if (!r->is_continues_humongous()) {
2476 r->object_iterate(_cl);
2477 }
2478 return false;
2479 }
2480 };
2481
2482 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2483 IterateObjectClosureRegionClosure blk(cl);
2484 heap_region_iterate(&blk);
2485 }
2486
2487 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2488 _hrm.iterate(cl);
2489 }
2490
2491 void
2492 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2493 uint worker_id,
2494 HeapRegionClaimer *hrclaimer,
2495 bool concurrent) const {
2496 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2497 }
2498
2499 // Clear the cached CSet starting regions and (more importantly)
2500 // the time stamps. Called when we reset the GC time stamp.
2501 void G1CollectedHeap::clear_cset_start_regions() {
2502 assert(_worker_cset_start_region != NULL, "sanity");
2503 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2504
2505 for (uint i = 0; i < ParallelGCThreads; i++) {
2506 _worker_cset_start_region[i] = NULL;
2507 _worker_cset_start_region_time_stamp[i] = 0;
2508 }
2509 }
2510
2511 // Given the id of a worker, obtain or calculate a suitable
2512 // starting region for iterating over the current collection set.
2513 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2514 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2515
2516 HeapRegion* result = NULL;
2517 unsigned gc_time_stamp = get_gc_time_stamp();
2518
2519 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2520 // Cached starting region for current worker was set
2521 // during the current pause - so it's valid.
2522 // Note: the cached starting heap region may be NULL
2523 // (when the collection set is empty).
2524 result = _worker_cset_start_region[worker_i];
2525 assert(result == NULL || result->in_collection_set(), "sanity");
2526 return result;
2527 }
2528
2529 // The cached entry was not valid so let's calculate
2530 // a suitable starting heap region for this worker.
2531
2532 // We want the parallel threads to start their collection
2533 // set iteration at different collection set regions to
2534 // avoid contention.
2535 // If we have:
2536 // n collection set regions
2537 // p threads
2538 // Then thread t will start at region floor ((t * n) / p)
2539
2540 result = g1_policy()->collection_set();
2541 uint cs_size = g1_policy()->cset_region_length();
2542 uint active_workers = workers()->active_workers();
2543
2544 uint end_ind = (cs_size * worker_i) / active_workers;
2545 uint start_ind = 0;
2546
2547 if (worker_i > 0 &&
2548 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2549 // Previous workers starting region is valid
2550 // so let's iterate from there
2551 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2552 result = _worker_cset_start_region[worker_i - 1];
2553 }
2554
2555 for (uint i = start_ind; i < end_ind; i++) {
2556 result = result->next_in_collection_set();
2557 }
2558
2559 // Note: the calculated starting heap region may be NULL
2560 // (when the collection set is empty).
2561 assert(result == NULL || result->in_collection_set(), "sanity");
2562 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2563 "should be updated only once per pause");
2564 _worker_cset_start_region[worker_i] = result;
2565 OrderAccess::storestore();
2566 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2567 return result;
2568 }
2569
2570 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2571 HeapRegion* r = g1_policy()->collection_set();
2572 while (r != NULL) {
2573 HeapRegion* next = r->next_in_collection_set();
2574 if (cl->doHeapRegion(r)) {
2575 cl->incomplete();
2576 return;
2577 }
2578 r = next;
2579 }
2580 }
2581
2582 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2583 HeapRegionClosure *cl) {
2584 if (r == NULL) {
2585 // The CSet is empty so there's nothing to do.
2586 return;
2587 }
2588
2589 assert(r->in_collection_set(),
2590 "Start region must be a member of the collection set.");
2591 HeapRegion* cur = r;
2592 while (cur != NULL) {
2593 HeapRegion* next = cur->next_in_collection_set();
2594 if (cl->doHeapRegion(cur) && false) {
2595 cl->incomplete();
2596 return;
2597 }
2598 cur = next;
2599 }
2600 cur = g1_policy()->collection_set();
2601 while (cur != r) {
2602 HeapRegion* next = cur->next_in_collection_set();
2603 if (cl->doHeapRegion(cur) && false) {
2604 cl->incomplete();
2605 return;
2606 }
2607 cur = next;
2608 }
2609 }
2610
2611 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2612 HeapRegion* result = _hrm.next_region_in_heap(from);
2613 while (result != NULL && result->is_pinned()) {
2614 result = _hrm.next_region_in_heap(result);
2615 }
2616 return result;
2617 }
2618
2619 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2620 HeapRegion* hr = heap_region_containing(addr);
2621 return hr->block_start(addr);
2622 }
2623
2624 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2625 HeapRegion* hr = heap_region_containing(addr);
2626 return hr->block_size(addr);
2627 }
2628
2629 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2630 HeapRegion* hr = heap_region_containing(addr);
2631 return hr->block_is_obj(addr);
2632 }
2633
2634 bool G1CollectedHeap::supports_tlab_allocation() const {
2635 return true;
2636 }
2637
2638 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2639 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2640 }
2641
2642 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2643 return young_list()->eden_used_bytes();
2644 }
2645
2646 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2647 // must be equal to the humongous object limit.
2648 size_t G1CollectedHeap::max_tlab_size() const {
2649 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2650 }
2651
2652 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2653 AllocationContext_t context = AllocationContext::current();
2654 return _allocator->unsafe_max_tlab_alloc(context);
2655 }
2656
2657 size_t G1CollectedHeap::max_capacity() const {
2658 return _hrm.reserved().byte_size();
2659 }
2660
2661 jlong G1CollectedHeap::millis_since_last_gc() {
2662 // assert(false, "NYI");
2663 return 0;
2664 }
2665
2666 void G1CollectedHeap::prepare_for_verify() {
2667 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2668 ensure_parsability(false);
2669 }
2670 g1_rem_set()->prepare_for_verify();
2671 }
2672
2673 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2674 VerifyOption vo) {
2675 switch (vo) {
2676 case VerifyOption_G1UsePrevMarking:
2677 return hr->obj_allocated_since_prev_marking(obj);
2678 case VerifyOption_G1UseNextMarking:
2679 return hr->obj_allocated_since_next_marking(obj);
2680 case VerifyOption_G1UseMarkWord:
2681 return false;
2682 default:
2683 ShouldNotReachHere();
2684 }
2685 return false; // keep some compilers happy
2686 }
2687
2688 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2689 switch (vo) {
2690 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2691 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2692 case VerifyOption_G1UseMarkWord: return NULL;
2693 default: ShouldNotReachHere();
2694 }
2695 return NULL; // keep some compilers happy
2696 }
2697
2698 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2699 switch (vo) {
2700 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2701 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2702 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2703 default: ShouldNotReachHere();
2704 }
2705 return false; // keep some compilers happy
2706 }
2707
2708 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2709 switch (vo) {
2710 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2711 case VerifyOption_G1UseNextMarking: return "NTAMS";
2712 case VerifyOption_G1UseMarkWord: return "NONE";
2713 default: ShouldNotReachHere();
2714 }
2715 return NULL; // keep some compilers happy
2716 }
2717
2718 class VerifyRootsClosure: public OopClosure {
2719 private:
2720 G1CollectedHeap* _g1h;
2721 VerifyOption _vo;
2722 bool _failures;
2723 public:
2724 // _vo == UsePrevMarking -> use "prev" marking information,
2725 // _vo == UseNextMarking -> use "next" marking information,
2726 // _vo == UseMarkWord -> use mark word from object header.
2727 VerifyRootsClosure(VerifyOption vo) :
2728 _g1h(G1CollectedHeap::heap()),
2729 _vo(vo),
2730 _failures(false) { }
2731
2732 bool failures() { return _failures; }
2733
2734 template <class T> void do_oop_nv(T* p) {
2735 T heap_oop = oopDesc::load_heap_oop(p);
2736 if (!oopDesc::is_null(heap_oop)) {
2737 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2738 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2739 LogHandle(gc, verify) log;
2740 log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2741 if (_vo == VerifyOption_G1UseMarkWord) {
2742 log.info(" Mark word: " PTR_FORMAT, p2i(obj->mark()));
2743 }
2744 ResourceMark rm;
2745 obj->print_on(log.info_stream());
2746 _failures = true;
2747 }
2748 }
2749 }
2750
2751 void do_oop(oop* p) { do_oop_nv(p); }
2752 void do_oop(narrowOop* p) { do_oop_nv(p); }
2753 };
2754
2755 class G1VerifyCodeRootOopClosure: public OopClosure {
2756 G1CollectedHeap* _g1h;
2757 OopClosure* _root_cl;
2758 nmethod* _nm;
2759 VerifyOption _vo;
2760 bool _failures;
2761
2762 template <class T> void do_oop_work(T* p) {
2763 // First verify that this root is live
2764 _root_cl->do_oop(p);
2765
2766 if (!G1VerifyHeapRegionCodeRoots) {
2767 // We're not verifying the code roots attached to heap region.
2768 return;
2769 }
2770
2771 // Don't check the code roots during marking verification in a full GC
2772 if (_vo == VerifyOption_G1UseMarkWord) {
2773 return;
2774 }
2775
2776 // Now verify that the current nmethod (which contains p) is
2777 // in the code root list of the heap region containing the
2778 // object referenced by p.
2779
2780 T heap_oop = oopDesc::load_heap_oop(p);
2781 if (!oopDesc::is_null(heap_oop)) {
2782 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2783
2784 // Now fetch the region containing the object
2785 HeapRegion* hr = _g1h->heap_region_containing(obj);
2786 HeapRegionRemSet* hrrs = hr->rem_set();
2787 // Verify that the strong code root list for this region
2788 // contains the nmethod
2789 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2790 log_info(gc, verify)("Code root location " PTR_FORMAT " "
2791 "from nmethod " PTR_FORMAT " not in strong "
2792 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2793 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2794 _failures = true;
2795 }
2796 }
2797 }
2798
2799 public:
2800 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2801 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2802
2803 void do_oop(oop* p) { do_oop_work(p); }
2804 void do_oop(narrowOop* p) { do_oop_work(p); }
2805
2806 void set_nmethod(nmethod* nm) { _nm = nm; }
2807 bool failures() { return _failures; }
2808 };
2809
2810 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2811 G1VerifyCodeRootOopClosure* _oop_cl;
2812
2813 public:
2814 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2815 _oop_cl(oop_cl) {}
2816
2817 void do_code_blob(CodeBlob* cb) {
2818 nmethod* nm = cb->as_nmethod_or_null();
2819 if (nm != NULL) {
2820 _oop_cl->set_nmethod(nm);
2821 nm->oops_do(_oop_cl);
2822 }
2823 }
2824 };
2825
2826 class YoungRefCounterClosure : public OopClosure {
2827 G1CollectedHeap* _g1h;
2828 int _count;
2829 public:
2830 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2831 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2832 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2833
2834 int count() { return _count; }
2835 void reset_count() { _count = 0; };
2836 };
2837
2838 class VerifyKlassClosure: public KlassClosure {
2839 YoungRefCounterClosure _young_ref_counter_closure;
2840 OopClosure *_oop_closure;
2841 public:
2842 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2843 void do_klass(Klass* k) {
2844 k->oops_do(_oop_closure);
2845
2846 _young_ref_counter_closure.reset_count();
2847 k->oops_do(&_young_ref_counter_closure);
2848 if (_young_ref_counter_closure.count() > 0) {
2849 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2850 }
2851 }
2852 };
2853
2854 class VerifyLivenessOopClosure: public OopClosure {
2855 G1CollectedHeap* _g1h;
2856 VerifyOption _vo;
2857 public:
2858 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2859 _g1h(g1h), _vo(vo)
2860 { }
2861 void do_oop(narrowOop *p) { do_oop_work(p); }
2862 void do_oop( oop *p) { do_oop_work(p); }
2863
2864 template <class T> void do_oop_work(T *p) {
2865 oop obj = oopDesc::load_decode_heap_oop(p);
2866 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2867 "Dead object referenced by a not dead object");
2868 }
2869 };
2870
2871 class VerifyObjsInRegionClosure: public ObjectClosure {
2872 private:
2873 G1CollectedHeap* _g1h;
2874 size_t _live_bytes;
2875 HeapRegion *_hr;
2876 VerifyOption _vo;
2877 public:
2878 // _vo == UsePrevMarking -> use "prev" marking information,
2879 // _vo == UseNextMarking -> use "next" marking information,
2880 // _vo == UseMarkWord -> use mark word from object header.
2881 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2882 : _live_bytes(0), _hr(hr), _vo(vo) {
2883 _g1h = G1CollectedHeap::heap();
2884 }
2885 void do_object(oop o) {
2886 VerifyLivenessOopClosure isLive(_g1h, _vo);
2887 assert(o != NULL, "Huh?");
2888 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2889 // If the object is alive according to the mark word,
2890 // then verify that the marking information agrees.
2891 // Note we can't verify the contra-positive of the
2892 // above: if the object is dead (according to the mark
2893 // word), it may not be marked, or may have been marked
2894 // but has since became dead, or may have been allocated
2895 // since the last marking.
2896 if (_vo == VerifyOption_G1UseMarkWord) {
2897 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2898 }
2899
2900 o->oop_iterate_no_header(&isLive);
2901 if (!_hr->obj_allocated_since_prev_marking(o)) {
2902 size_t obj_size = o->size(); // Make sure we don't overflow
2903 _live_bytes += (obj_size * HeapWordSize);
2904 }
2905 }
2906 }
2907 size_t live_bytes() { return _live_bytes; }
2908 };
2909
2910 class VerifyArchiveOopClosure: public OopClosure {
2911 public:
2912 VerifyArchiveOopClosure(HeapRegion *hr) { }
2913 void do_oop(narrowOop *p) { do_oop_work(p); }
2914 void do_oop( oop *p) { do_oop_work(p); }
2915
2916 template <class T> void do_oop_work(T *p) {
2917 oop obj = oopDesc::load_decode_heap_oop(p);
2918 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2919 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2920 p2i(p), p2i(obj));
2921 }
2922 };
2923
2924 class VerifyArchiveRegionClosure: public ObjectClosure {
2925 public:
2926 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2927 // Verify that all object pointers are to archive regions.
2928 void do_object(oop o) {
2929 VerifyArchiveOopClosure checkOop(NULL);
2930 assert(o != NULL, "Should not be here for NULL oops");
2931 o->oop_iterate_no_header(&checkOop);
2932 }
2933 };
2934
2935 class VerifyRegionClosure: public HeapRegionClosure {
2936 private:
2937 bool _par;
2938 VerifyOption _vo;
2939 bool _failures;
2940 public:
2941 // _vo == UsePrevMarking -> use "prev" marking information,
2942 // _vo == UseNextMarking -> use "next" marking information,
2943 // _vo == UseMarkWord -> use mark word from object header.
2944 VerifyRegionClosure(bool par, VerifyOption vo)
2945 : _par(par),
2946 _vo(vo),
2947 _failures(false) {}
2948
2949 bool failures() {
2950 return _failures;
2951 }
2952
2953 bool doHeapRegion(HeapRegion* r) {
2954 // For archive regions, verify there are no heap pointers to
2955 // non-pinned regions. For all others, verify liveness info.
2956 if (r->is_archive()) {
2957 VerifyArchiveRegionClosure verify_oop_pointers(r);
2958 r->object_iterate(&verify_oop_pointers);
2959 return true;
2960 }
2961 if (!r->is_continues_humongous()) {
2962 bool failures = false;
2963 r->verify(_vo, &failures);
2964 if (failures) {
2965 _failures = true;
2966 } else if (!r->is_starts_humongous()) {
2967 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2968 r->object_iterate(¬_dead_yet_cl);
2969 if (_vo != VerifyOption_G1UseNextMarking) {
2970 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2971 log_info(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
2972 p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
2973 _failures = true;
2974 }
2975 } else {
2976 // When vo == UseNextMarking we cannot currently do a sanity
2977 // check on the live bytes as the calculation has not been
2978 // finalized yet.
2979 }
2980 }
2981 }
2982 return false; // stop the region iteration if we hit a failure
2983 }
2984 };
2985
2986 // This is the task used for parallel verification of the heap regions
2987
2988 class G1ParVerifyTask: public AbstractGangTask {
2989 private:
2990 G1CollectedHeap* _g1h;
2991 VerifyOption _vo;
2992 bool _failures;
2993 HeapRegionClaimer _hrclaimer;
2994
2995 public:
2996 // _vo == UsePrevMarking -> use "prev" marking information,
2997 // _vo == UseNextMarking -> use "next" marking information,
2998 // _vo == UseMarkWord -> use mark word from object header.
2999 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3000 AbstractGangTask("Parallel verify task"),
3001 _g1h(g1h),
3002 _vo(vo),
3003 _failures(false),
3004 _hrclaimer(g1h->workers()->active_workers()) {}
3005
3006 bool failures() {
3007 return _failures;
3008 }
3009
3010 void work(uint worker_id) {
3011 HandleMark hm;
3012 VerifyRegionClosure blk(true, _vo);
3013 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3014 if (blk.failures()) {
3015 _failures = true;
3016 }
3017 }
3018 };
3019
3020 void G1CollectedHeap::verify(VerifyOption vo) {
3021 if (!SafepointSynchronize::is_at_safepoint()) {
3022 log_info(gc, verify)("Skipping verification. Not at safepoint.");
3023 }
3024
3025 assert(Thread::current()->is_VM_thread(),
3026 "Expected to be executed serially by the VM thread at this point");
3027
3028 log_debug(gc, verify)("Roots");
3029 VerifyRootsClosure rootsCl(vo);
3030 VerifyKlassClosure klassCl(this, &rootsCl);
3031 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3032
3033 // We apply the relevant closures to all the oops in the
3034 // system dictionary, class loader data graph, the string table
3035 // and the nmethods in the code cache.
3036 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3037 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3038
3039 {
3040 G1RootProcessor root_processor(this, 1);
3041 root_processor.process_all_roots(&rootsCl,
3042 &cldCl,
3043 &blobsCl);
3044 }
3045
3046 bool failures = rootsCl.failures() || codeRootsCl.failures();
3047
3048 if (vo != VerifyOption_G1UseMarkWord) {
3049 // If we're verifying during a full GC then the region sets
3050 // will have been torn down at the start of the GC. Therefore
3051 // verifying the region sets will fail. So we only verify
3052 // the region sets when not in a full GC.
3053 log_debug(gc, verify)("HeapRegionSets");
3054 verify_region_sets();
3055 }
3056
3057 log_debug(gc, verify)("HeapRegions");
3058 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3059
3060 G1ParVerifyTask task(this, vo);
3061 workers()->run_task(&task);
3062 if (task.failures()) {
3063 failures = true;
3064 }
3065
3066 } else {
3067 VerifyRegionClosure blk(false, vo);
3068 heap_region_iterate(&blk);
3069 if (blk.failures()) {
3070 failures = true;
3071 }
3072 }
3073
3074 if (G1StringDedup::is_enabled()) {
3075 log_debug(gc, verify)("StrDedup");
3076 G1StringDedup::verify();
3077 }
3078
3079 if (failures) {
3080 log_info(gc, verify)("Heap after failed verification:");
3081 // It helps to have the per-region information in the output to
3082 // help us track down what went wrong. This is why we call
3083 // print_extended_on() instead of print_on().
3084 LogHandle(gc, verify) log;
3085 ResourceMark rm;
3086 print_extended_on(log.info_stream());
3087 }
3088 guarantee(!failures, "there should not have been any failures");
3089 }
3090
3091 double G1CollectedHeap::verify(bool guard, const char* msg) {
3092 double verify_time_ms = 0.0;
3093
3094 if (guard && total_collections() >= VerifyGCStartAt) {
3095 double verify_start = os::elapsedTime();
3096 HandleMark hm; // Discard invalid handles created during verification
3097 prepare_for_verify();
3098 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3099 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3100 }
3101
3102 return verify_time_ms;
3103 }
3104
3105 void G1CollectedHeap::verify_before_gc() {
3106 double verify_time_ms = verify(VerifyBeforeGC, "Before GC");
3107 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3108 }
3109
3110 void G1CollectedHeap::verify_after_gc() {
3111 double verify_time_ms = verify(VerifyAfterGC, "After GC");
3112 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3113 }
3114
3115 class PrintRegionClosure: public HeapRegionClosure {
3116 outputStream* _st;
3117 public:
3118 PrintRegionClosure(outputStream* st) : _st(st) {}
3119 bool doHeapRegion(HeapRegion* r) {
3120 r->print_on(_st);
3121 return false;
3122 }
3123 };
3124
3125 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3126 const HeapRegion* hr,
3127 const VerifyOption vo) const {
3128 switch (vo) {
3129 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3130 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3131 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3132 default: ShouldNotReachHere();
3133 }
3134 return false; // keep some compilers happy
3135 }
3136
3137 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3138 const VerifyOption vo) const {
3139 switch (vo) {
3140 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3141 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3142 case VerifyOption_G1UseMarkWord: {
3143 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3144 return !obj->is_gc_marked() && !hr->is_archive();
3145 }
3146 default: ShouldNotReachHere();
3147 }
3148 return false; // keep some compilers happy
3149 }
3150
3151 void G1CollectedHeap::print_on(outputStream* st) const {
3152 st->print(" %-20s", "garbage-first heap");
3153 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3154 capacity()/K, used_unlocked()/K);
3155 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3156 p2i(_hrm.reserved().start()),
3157 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3158 p2i(_hrm.reserved().end()));
3159 st->cr();
3160 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3161 uint young_regions = _young_list->length();
3162 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3163 (size_t) young_regions * HeapRegion::GrainBytes / K);
3164 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3165 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3166 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3167 st->cr();
3168 MetaspaceAux::print_on(st);
3169 }
3170
3171 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3172 print_on(st);
3173
3174 // Print the per-region information.
3175 st->cr();
3176 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
3177 "HS=humongous(starts), HC=humongous(continues), "
3178 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3179 "AC=allocation context, "
3180 "TAMS=top-at-mark-start (previous, next)");
3181 PrintRegionClosure blk(st);
3182 heap_region_iterate(&blk);
3183 }
3184
3185 void G1CollectedHeap::print_on_error(outputStream* st) const {
3186 this->CollectedHeap::print_on_error(st);
3187
3188 if (_cm != NULL) {
3189 st->cr();
3190 _cm->print_on_error(st);
3191 }
3192 }
3193
3194 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3195 workers()->print_worker_threads_on(st);
3196 _cmThread->print_on(st);
3197 st->cr();
3198 _cm->print_worker_threads_on(st);
3199 _cg1r->print_worker_threads_on(st);
3200 if (G1StringDedup::is_enabled()) {
3201 G1StringDedup::print_worker_threads_on(st);
3202 }
3203 }
3204
3205 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3206 workers()->threads_do(tc);
3207 tc->do_thread(_cmThread);
3208 _cg1r->threads_do(tc);
3209 if (G1StringDedup::is_enabled()) {
3210 G1StringDedup::threads_do(tc);
3211 }
3212 }
3213
3214 void G1CollectedHeap::print_tracing_info() const {
3215 // We'll overload this to mean "trace GC pause statistics."
3216 if (TraceYoungGenTime || TraceOldGenTime) {
3217 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3218 // to that.
3219 g1_policy()->print_tracing_info();
3220 }
3221 g1_rem_set()->print_summary_info();
3222 concurrent_mark()->print_summary_info();
3223 g1_policy()->print_yg_surv_rate_info();
3224 }
3225
3226 #ifndef PRODUCT
3227 // Helpful for debugging RSet issues.
3228
3229 class PrintRSetsClosure : public HeapRegionClosure {
3230 private:
3231 const char* _msg;
3232 size_t _occupied_sum;
3233
3234 public:
3235 bool doHeapRegion(HeapRegion* r) {
3236 HeapRegionRemSet* hrrs = r->rem_set();
3237 size_t occupied = hrrs->occupied();
3238 _occupied_sum += occupied;
3239
3240 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
3241 if (occupied == 0) {
3242 tty->print_cr(" RSet is empty");
3243 } else {
3244 hrrs->print();
3245 }
3246 tty->print_cr("----------");
3247 return false;
3248 }
3249
3250 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3251 tty->cr();
3252 tty->print_cr("========================================");
3253 tty->print_cr("%s", msg);
3254 tty->cr();
3255 }
3256
3257 ~PrintRSetsClosure() {
3258 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3259 tty->print_cr("========================================");
3260 tty->cr();
3261 }
3262 };
3263
3264 void G1CollectedHeap::print_cset_rsets() {
3265 PrintRSetsClosure cl("Printing CSet RSets");
3266 collection_set_iterate(&cl);
3267 }
3268
3269 void G1CollectedHeap::print_all_rsets() {
3270 PrintRSetsClosure cl("Printing All RSets");;
3271 heap_region_iterate(&cl);
3272 }
3273 #endif // PRODUCT
3274
3275 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3276 YoungList* young_list = heap()->young_list();
3277
3278 size_t eden_used_bytes = young_list->eden_used_bytes();
3279 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3280
3281 size_t eden_capacity_bytes =
3282 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3283
3284 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3285 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3286 }
3287
3288 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3289 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3290 stats->unused(), stats->used(), stats->region_end_waste(),
3291 stats->regions_filled(), stats->direct_allocated(),
3292 stats->failure_used(), stats->failure_waste());
3293 }
3294
3295 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3296 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3297 gc_tracer->report_gc_heap_summary(when, heap_summary);
3298
3299 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3300 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3301 }
3302
3303
3304 G1CollectedHeap* G1CollectedHeap::heap() {
3305 CollectedHeap* heap = Universe::heap();
3306 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3307 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3308 return (G1CollectedHeap*)heap;
3309 }
3310
3311 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3312 // always_do_update_barrier = false;
3313 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3314 // Fill TLAB's and such
3315 accumulate_statistics_all_tlabs();
3316 ensure_parsability(true);
3317
3318 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
3319 }
3320
3321 void G1CollectedHeap::gc_epilogue(bool full) {
3322 // we are at the end of the GC. Total collections has already been increased.
3323 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
3324
3325 // FIXME: what is this about?
3326 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3327 // is set.
3328 #if defined(COMPILER2) || INCLUDE_JVMCI
3329 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3330 #endif
3331 // always_do_update_barrier = true;
3332
3333 resize_all_tlabs();
3334 allocation_context_stats().update(full);
3335
3336 // We have just completed a GC. Update the soft reference
3337 // policy with the new heap occupancy
3338 Universe::update_heap_info_at_gc();
3339 }
3340
3341 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3342 uint gc_count_before,
3343 bool* succeeded,
3344 GCCause::Cause gc_cause) {
3345 assert_heap_not_locked_and_not_at_safepoint();
3346 g1_policy()->record_stop_world_start();
3347 VM_G1IncCollectionPause op(gc_count_before,
3348 word_size,
3349 false, /* should_initiate_conc_mark */
3350 g1_policy()->max_pause_time_ms(),
3351 gc_cause);
3352
3353 op.set_allocation_context(AllocationContext::current());
3354 VMThread::execute(&op);
3355
3356 HeapWord* result = op.result();
3357 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3358 assert(result == NULL || ret_succeeded,
3359 "the result should be NULL if the VM did not succeed");
3360 *succeeded = ret_succeeded;
3361
3362 assert_heap_not_locked();
3363 return result;
3364 }
3365
3366 void
3367 G1CollectedHeap::doConcurrentMark() {
3368 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3369 if (!_cmThread->in_progress()) {
3370 _cmThread->set_started();
3371 CGC_lock->notify();
3372 }
3373 }
3374
3375 size_t G1CollectedHeap::pending_card_num() {
3376 size_t extra_cards = 0;
3377 JavaThread *curr = Threads::first();
3378 while (curr != NULL) {
3379 DirtyCardQueue& dcq = curr->dirty_card_queue();
3380 extra_cards += dcq.size();
3381 curr = curr->next();
3382 }
3383 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3384 size_t buffer_size = dcqs.buffer_size();
3385 size_t buffer_num = dcqs.completed_buffers_num();
3386
3387 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3388 // in bytes - not the number of 'entries'. We need to convert
3389 // into a number of cards.
3390 return (buffer_size * buffer_num + extra_cards) / oopSize;
3391 }
3392
3393 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3394 private:
3395 size_t _total_humongous;
3396 size_t _candidate_humongous;
3397
3398 DirtyCardQueue _dcq;
3399
3400 // We don't nominate objects with many remembered set entries, on
3401 // the assumption that such objects are likely still live.
3402 bool is_remset_small(HeapRegion* region) const {
3403 HeapRegionRemSet* const rset = region->rem_set();
3404 return G1EagerReclaimHumongousObjectsWithStaleRefs
3405 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3406 : rset->is_empty();
3407 }
3408
3409 bool is_typeArray_region(HeapRegion* region) const {
3410 return oop(region->bottom())->is_typeArray();
3411 }
3412
3413 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3414 assert(region->is_starts_humongous(), "Must start a humongous object");
3415
3416 // Candidate selection must satisfy the following constraints
3417 // while concurrent marking is in progress:
3418 //
3419 // * In order to maintain SATB invariants, an object must not be
3420 // reclaimed if it was allocated before the start of marking and
3421 // has not had its references scanned. Such an object must have
3422 // its references (including type metadata) scanned to ensure no
3423 // live objects are missed by the marking process. Objects
3424 // allocated after the start of concurrent marking don't need to
3425 // be scanned.
3426 //
3427 // * An object must not be reclaimed if it is on the concurrent
3428 // mark stack. Objects allocated after the start of concurrent
3429 // marking are never pushed on the mark stack.
3430 //
3431 // Nominating only objects allocated after the start of concurrent
3432 // marking is sufficient to meet both constraints. This may miss
3433 // some objects that satisfy the constraints, but the marking data
3434 // structures don't support efficiently performing the needed
3435 // additional tests or scrubbing of the mark stack.
3436 //
3437 // However, we presently only nominate is_typeArray() objects.
3438 // A humongous object containing references induces remembered
3439 // set entries on other regions. In order to reclaim such an
3440 // object, those remembered sets would need to be cleaned up.
3441 //
3442 // We also treat is_typeArray() objects specially, allowing them
3443 // to be reclaimed even if allocated before the start of
3444 // concurrent mark. For this we rely on mark stack insertion to
3445 // exclude is_typeArray() objects, preventing reclaiming an object
3446 // that is in the mark stack. We also rely on the metadata for
3447 // such objects to be built-in and so ensured to be kept live.
3448 // Frequent allocation and drop of large binary blobs is an
3449 // important use case for eager reclaim, and this special handling
3450 // may reduce needed headroom.
3451
3452 return is_typeArray_region(region) && is_remset_small(region);
3453 }
3454
3455 public:
3456 RegisterHumongousWithInCSetFastTestClosure()
3457 : _total_humongous(0),
3458 _candidate_humongous(0),
3459 _dcq(&JavaThread::dirty_card_queue_set()) {
3460 }
3461
3462 virtual bool doHeapRegion(HeapRegion* r) {
3463 if (!r->is_starts_humongous()) {
3464 return false;
3465 }
3466 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3467
3468 bool is_candidate = humongous_region_is_candidate(g1h, r);
3469 uint rindex = r->hrm_index();
3470 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3471 if (is_candidate) {
3472 _candidate_humongous++;
3473 g1h->register_humongous_region_with_cset(rindex);
3474 // Is_candidate already filters out humongous object with large remembered sets.
3475 // If we have a humongous object with a few remembered sets, we simply flush these
3476 // remembered set entries into the DCQS. That will result in automatic
3477 // re-evaluation of their remembered set entries during the following evacuation
3478 // phase.
3479 if (!r->rem_set()->is_empty()) {
3480 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3481 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3482 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3483 HeapRegionRemSetIterator hrrs(r->rem_set());
3484 size_t card_index;
3485 while (hrrs.has_next(card_index)) {
3486 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3487 // The remembered set might contain references to already freed
3488 // regions. Filter out such entries to avoid failing card table
3489 // verification.
3490 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3491 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3492 *card_ptr = CardTableModRefBS::dirty_card_val();
3493 _dcq.enqueue(card_ptr);
3494 }
3495 }
3496 }
3497 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3498 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3499 hrrs.n_yielded(), r->rem_set()->occupied());
3500 r->rem_set()->clear_locked();
3501 }
3502 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3503 }
3504 _total_humongous++;
3505
3506 return false;
3507 }
3508
3509 size_t total_humongous() const { return _total_humongous; }
3510 size_t candidate_humongous() const { return _candidate_humongous; }
3511
3512 void flush_rem_set_entries() { _dcq.flush(); }
3513 };
3514
3515 void G1CollectedHeap::register_humongous_regions_with_cset() {
3516 if (!G1EagerReclaimHumongousObjects) {
3517 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3518 return;
3519 }
3520 double time = os::elapsed_counter();
3521
3522 // Collect reclaim candidate information and register candidates with cset.
3523 RegisterHumongousWithInCSetFastTestClosure cl;
3524 heap_region_iterate(&cl);
3525
3526 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3527 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3528 cl.total_humongous(),
3529 cl.candidate_humongous());
3530 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3531
3532 // Finally flush all remembered set entries to re-check into the global DCQS.
3533 cl.flush_rem_set_entries();
3534 }
3535
3536 #ifdef ASSERT
3537 class VerifyCSetClosure: public HeapRegionClosure {
3538 public:
3539 bool doHeapRegion(HeapRegion* hr) {
3540 // Here we check that the CSet region's RSet is ready for parallel
3541 // iteration. The fields that we'll verify are only manipulated
3542 // when the region is part of a CSet and is collected. Afterwards,
3543 // we reset these fields when we clear the region's RSet (when the
3544 // region is freed) so they are ready when the region is
3545 // re-allocated. The only exception to this is if there's an
3546 // evacuation failure and instead of freeing the region we leave
3547 // it in the heap. In that case, we reset these fields during
3548 // evacuation failure handling.
3549 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3550
3551 // Here's a good place to add any other checks we'd like to
3552 // perform on CSet regions.
3553 return false;
3554 }
3555 };
3556 #endif // ASSERT
3557
3558 uint G1CollectedHeap::num_task_queues() const {
3559 return _task_queues->size();
3560 }
3561
3562 #if TASKQUEUE_STATS
3563 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3564 st->print_raw_cr("GC Task Stats");
3565 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3566 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3567 }
3568
3569 void G1CollectedHeap::print_taskqueue_stats() const {
3570 if (!develop_log_is_enabled(Trace, gc, task, stats)) {
3571 return;
3572 }
3573 LogHandle(gc, task, stats) log;
3574 ResourceMark rm;
3575 outputStream* st = log.trace_stream();
3576
3577 print_taskqueue_stats_hdr(st);
3578
3579 TaskQueueStats totals;
3580 const uint n = num_task_queues();
3581 for (uint i = 0; i < n; ++i) {
3582 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3583 totals += task_queue(i)->stats;
3584 }
3585 st->print_raw("tot "); totals.print(st); st->cr();
3586
3587 DEBUG_ONLY(totals.verify());
3588 }
3589
3590 void G1CollectedHeap::reset_taskqueue_stats() {
3591 const uint n = num_task_queues();
3592 for (uint i = 0; i < n; ++i) {
3593 task_queue(i)->stats.reset();
3594 }
3595 }
3596 #endif // TASKQUEUE_STATS
3597
3598 void G1CollectedHeap::log_gc_footer(jlong pause_time_counter) {
3599 if (evacuation_failed()) {
3600 log_info(gc)("To-space exhausted");
3601 }
3602
3603 double pause_time_ms = TimeHelper::counter_to_millis(pause_time_counter);
3604 g1_policy()->print_phases(pause_time_ms);
3605
3606 g1_policy()->print_detailed_heap_transition();
3607 }
3608
3609
3610 void G1CollectedHeap::wait_for_root_region_scanning() {
3611 double scan_wait_start = os::elapsedTime();
3612 // We have to wait until the CM threads finish scanning the
3613 // root regions as it's the only way to ensure that all the
3614 // objects on them have been correctly scanned before we start
3615 // moving them during the GC.
3616 bool waited = _cm->root_regions()->wait_until_scan_finished();
3617 double wait_time_ms = 0.0;
3618 if (waited) {
3619 double scan_wait_end = os::elapsedTime();
3620 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3621 }
3622 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3623 }
3624
3625 bool
3626 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3627 assert_at_safepoint(true /* should_be_vm_thread */);
3628 guarantee(!is_gc_active(), "collection is not reentrant");
3629
3630 if (GC_locker::check_active_before_gc()) {
3631 return false;
3632 }
3633
3634 _gc_timer_stw->register_gc_start();
3635
3636 GCIdMark gc_id_mark;
3637 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3638
3639 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3640 ResourceMark rm;
3641
3642 wait_for_root_region_scanning();
3643
3644 print_heap_before_gc();
3645 trace_heap_before_gc(_gc_tracer_stw);
3646
3647 verify_region_sets_optional();
3648 verify_dirty_young_regions();
3649
3650 // This call will decide whether this pause is an initial-mark
3651 // pause. If it is, during_initial_mark_pause() will return true
3652 // for the duration of this pause.
3653 g1_policy()->decide_on_conc_mark_initiation();
3654
3655 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3656 assert(!collector_state()->during_initial_mark_pause() ||
3657 collector_state()->gcs_are_young(), "sanity");
3658
3659 // We also do not allow mixed GCs during marking.
3660 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3661
3662 // Record whether this pause is an initial mark. When the current
3663 // thread has completed its logging output and it's safe to signal
3664 // the CM thread, the flag's value in the policy has been reset.
3665 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3666
3667 // Inner scope for scope based logging, timers, and stats collection
3668 {
3669 EvacuationInfo evacuation_info;
3670
3671 if (collector_state()->during_initial_mark_pause()) {
3672 // We are about to start a marking cycle, so we increment the
3673 // full collection counter.
3674 increment_old_marking_cycles_started();
3675 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3676 }
3677
3678 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3679
3680 GCTraceCPUTime tcpu;
3681
3682 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3683 workers()->active_workers(),
3684 Threads::number_of_non_daemon_threads());
3685 workers()->set_active_workers(active_workers);
3686 FormatBuffer<> gc_string("Pause ");
3687 if (collector_state()->during_initial_mark_pause()) {
3688 gc_string.append("Initial Mark");
3689 } else if (collector_state()->gcs_are_young()) {
3690 gc_string.append("Young");
3691 } else {
3692 gc_string.append("Mixed");
3693 }
3694 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3695
3696 jlong pause_start_counter = os::elapsed_counter();
3697 g1_policy()->note_gc_start(active_workers);
3698
3699 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3700 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3701
3702 // If the secondary_free_list is not empty, append it to the
3703 // free_list. No need to wait for the cleanup operation to finish;
3704 // the region allocation code will check the secondary_free_list
3705 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3706 // set, skip this step so that the region allocation code has to
3707 // get entries from the secondary_free_list.
3708 if (!G1StressConcRegionFreeing) {
3709 append_secondary_free_list_if_not_empty_with_lock();
3710 }
3711
3712 assert(check_young_list_well_formed(), "young list should be well formed");
3713
3714 // Don't dynamically change the number of GC threads this early. A value of
3715 // 0 is used to indicate serial work. When parallel work is done,
3716 // it will be set.
3717
3718 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3719 IsGCActiveMark x;
3720
3721 gc_prologue(false);
3722 increment_total_collections(false /* full gc */);
3723 increment_gc_time_stamp();
3724
3725 verify_before_gc();
3726
3727 check_bitmaps("GC Start");
3728
3729 #if defined(COMPILER2) || INCLUDE_JVMCI
3730 DerivedPointerTable::clear();
3731 #endif
3732
3733 // Please see comment in g1CollectedHeap.hpp and
3734 // G1CollectedHeap::ref_processing_init() to see how
3735 // reference processing currently works in G1.
3736
3737 // Enable discovery in the STW reference processor
3738 if (g1_policy()->should_process_references()) {
3739 ref_processor_stw()->enable_discovery();
3740 } else {
3741 ref_processor_stw()->disable_discovery();
3742 }
3743
3744 {
3745 // We want to temporarily turn off discovery by the
3746 // CM ref processor, if necessary, and turn it back on
3747 // on again later if we do. Using a scoped
3748 // NoRefDiscovery object will do this.
3749 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3750
3751 // Forget the current alloc region (we might even choose it to be part
3752 // of the collection set!).
3753 _allocator->release_mutator_alloc_region();
3754
3755 // This timing is only used by the ergonomics to handle our pause target.
3756 // It is unclear why this should not include the full pause. We will
3757 // investigate this in CR 7178365.
3758 //
3759 // Preserving the old comment here if that helps the investigation:
3760 //
3761 // The elapsed time induced by the start time below deliberately elides
3762 // the possible verification above.
3763 double sample_start_time_sec = os::elapsedTime();
3764
3765 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3766
3767 if (collector_state()->during_initial_mark_pause()) {
3768 concurrent_mark()->checkpointRootsInitialPre();
3769 }
3770
3771 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3772 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3773
3774 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3775
3776 // Make sure the remembered sets are up to date. This needs to be
3777 // done before register_humongous_regions_with_cset(), because the
3778 // remembered sets are used there to choose eager reclaim candidates.
3779 // If the remembered sets are not up to date we might miss some
3780 // entries that need to be handled.
3781 g1_rem_set()->cleanupHRRS();
3782
3783 register_humongous_regions_with_cset();
3784
3785 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3786
3787 _cm->note_start_of_gc();
3788 // We call this after finalize_cset() to
3789 // ensure that the CSet has been finalized.
3790 _cm->verify_no_cset_oops();
3791
3792 if (_hr_printer.is_active()) {
3793 HeapRegion* hr = g1_policy()->collection_set();
3794 while (hr != NULL) {
3795 _hr_printer.cset(hr);
3796 hr = hr->next_in_collection_set();
3797 }
3798 }
3799
3800 #ifdef ASSERT
3801 VerifyCSetClosure cl;
3802 collection_set_iterate(&cl);
3803 #endif // ASSERT
3804
3805 // Initialize the GC alloc regions.
3806 _allocator->init_gc_alloc_regions(evacuation_info);
3807
3808 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3809 pre_evacuate_collection_set();
3810
3811 // Actually do the work...
3812 evacuate_collection_set(evacuation_info, &per_thread_states);
3813
3814 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3815
3816 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3817 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3818
3819 eagerly_reclaim_humongous_regions();
3820
3821 g1_policy()->clear_collection_set();
3822
3823 // Start a new incremental collection set for the next pause.
3824 g1_policy()->start_incremental_cset_building();
3825
3826 clear_cset_fast_test();
3827
3828 _young_list->reset_sampled_info();
3829
3830 // Don't check the whole heap at this point as the
3831 // GC alloc regions from this pause have been tagged
3832 // as survivors and moved on to the survivor list.
3833 // Survivor regions will fail the !is_young() check.
3834 assert(check_young_list_empty(false /* check_heap */),
3835 "young list should be empty");
3836
3837 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3838 _young_list->first_survivor_region(),
3839 _young_list->last_survivor_region());
3840
3841 _young_list->reset_auxilary_lists();
3842
3843 if (evacuation_failed()) {
3844 set_used(recalculate_used());
3845 if (_archive_allocator != NULL) {
3846 _archive_allocator->clear_used();
3847 }
3848 for (uint i = 0; i < ParallelGCThreads; i++) {
3849 if (_evacuation_failed_info_array[i].has_failed()) {
3850 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3851 }
3852 }
3853 } else {
3854 // The "used" of the the collection set have already been subtracted
3855 // when they were freed. Add in the bytes evacuated.
3856 increase_used(g1_policy()->bytes_copied_during_gc());
3857 }
3858
3859 if (collector_state()->during_initial_mark_pause()) {
3860 // We have to do this before we notify the CM threads that
3861 // they can start working to make sure that all the
3862 // appropriate initialization is done on the CM object.
3863 concurrent_mark()->checkpointRootsInitialPost();
3864 collector_state()->set_mark_in_progress(true);
3865 // Note that we don't actually trigger the CM thread at
3866 // this point. We do that later when we're sure that
3867 // the current thread has completed its logging output.
3868 }
3869
3870 allocate_dummy_regions();
3871
3872 _allocator->init_mutator_alloc_region();
3873
3874 {
3875 size_t expand_bytes = g1_policy()->expansion_amount();
3876 if (expand_bytes > 0) {
3877 size_t bytes_before = capacity();
3878 // No need for an ergo logging here,
3879 // expansion_amount() does this when it returns a value > 0.
3880 double expand_ms;
3881 if (!expand(expand_bytes, &expand_ms)) {
3882 // We failed to expand the heap. Cannot do anything about it.
3883 }
3884 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3885 }
3886 }
3887
3888 // We redo the verification but now wrt to the new CSet which
3889 // has just got initialized after the previous CSet was freed.
3890 _cm->verify_no_cset_oops();
3891 _cm->note_end_of_gc();
3892
3893 // This timing is only used by the ergonomics to handle our pause target.
3894 // It is unclear why this should not include the full pause. We will
3895 // investigate this in CR 7178365.
3896 double sample_end_time_sec = os::elapsedTime();
3897 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3898 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3899 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3900
3901 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3902 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3903
3904 MemoryService::track_memory_usage();
3905
3906 // In prepare_for_verify() below we'll need to scan the deferred
3907 // update buffers to bring the RSets up-to-date if
3908 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3909 // the update buffers we'll probably need to scan cards on the
3910 // regions we just allocated to (i.e., the GC alloc
3911 // regions). However, during the last GC we called
3912 // set_saved_mark() on all the GC alloc regions, so card
3913 // scanning might skip the [saved_mark_word()...top()] area of
3914 // those regions (i.e., the area we allocated objects into
3915 // during the last GC). But it shouldn't. Given that
3916 // saved_mark_word() is conditional on whether the GC time stamp
3917 // on the region is current or not, by incrementing the GC time
3918 // stamp here we invalidate all the GC time stamps on all the
3919 // regions and saved_mark_word() will simply return top() for
3920 // all the regions. This is a nicer way of ensuring this rather
3921 // than iterating over the regions and fixing them. In fact, the
3922 // GC time stamp increment here also ensures that
3923 // saved_mark_word() will return top() between pauses, i.e.,
3924 // during concurrent refinement. So we don't need the
3925 // is_gc_active() check to decided which top to use when
3926 // scanning cards (see CR 7039627).
3927 increment_gc_time_stamp();
3928
3929 verify_after_gc();
3930 check_bitmaps("GC End");
3931
3932 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3933 ref_processor_stw()->verify_no_references_recorded();
3934
3935 // CM reference discovery will be re-enabled if necessary.
3936 }
3937
3938 #ifdef TRACESPINNING
3939 ParallelTaskTerminator::print_termination_counts();
3940 #endif
3941
3942 gc_epilogue(false);
3943 }
3944
3945 // Print the remainder of the GC log output.
3946 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3947
3948 // It is not yet to safe to tell the concurrent mark to
3949 // start as we have some optional output below. We don't want the
3950 // output from the concurrent mark thread interfering with this
3951 // logging output either.
3952
3953 _hrm.verify_optional();
3954 verify_region_sets_optional();
3955
3956 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3957 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3958
3959 print_heap_after_gc();
3960 trace_heap_after_gc(_gc_tracer_stw);
3961
3962 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3963 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3964 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3965 // before any GC notifications are raised.
3966 g1mm()->update_sizes();
3967
3968 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3969 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3970 _gc_timer_stw->register_gc_end();
3971 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3972 }
3973 // It should now be safe to tell the concurrent mark thread to start
3974 // without its logging output interfering with the logging output
3975 // that came from the pause.
3976
3977 if (should_start_conc_mark) {
3978 // CAUTION: after the doConcurrentMark() call below,
3979 // the concurrent marking thread(s) could be running
3980 // concurrently with us. Make sure that anything after
3981 // this point does not assume that we are the only GC thread
3982 // running. Note: of course, the actual marking work will
3983 // not start until the safepoint itself is released in
3984 // SuspendibleThreadSet::desynchronize().
3985 doConcurrentMark();
3986 }
3987
3988 return true;
3989 }
3990
3991 void G1CollectedHeap::restore_preserved_marks() {
3992 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3993 workers()->run_task(&rpm_task);
3994 }
3995
3996 void G1CollectedHeap::remove_self_forwarding_pointers() {
3997 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3998 workers()->run_task(&rsfp_task);
3999 }
4000
4001 void G1CollectedHeap::restore_after_evac_failure() {
4002 double remove_self_forwards_start = os::elapsedTime();
4003
4004 remove_self_forwarding_pointers();
4005 restore_preserved_marks();
4006
4007 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4008 }
4009
4010 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4011 if (!_evacuation_failed) {
4012 _evacuation_failed = true;
4013 }
4014
4015 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4016
4017 // We want to call the "for_promotion_failure" version only in the
4018 // case of a promotion failure.
4019 if (m->must_be_preserved_for_promotion_failure(obj)) {
4020 OopAndMarkOop elem(obj, m);
4021 _preserved_objs[worker_id].push(elem);
4022 }
4023 }
4024
4025 bool G1ParEvacuateFollowersClosure::offer_termination() {
4026 G1ParScanThreadState* const pss = par_scan_state();
4027 start_term_time();
4028 const bool res = terminator()->offer_termination();
4029 end_term_time();
4030 return res;
4031 }
4032
4033 void G1ParEvacuateFollowersClosure::do_void() {
4034 G1ParScanThreadState* const pss = par_scan_state();
4035 pss->trim_queue();
4036 do {
4037 pss->steal_and_trim_queue(queues());
4038 } while (!offer_termination());
4039 }
4040
4041 class G1ParTask : public AbstractGangTask {
4042 protected:
4043 G1CollectedHeap* _g1h;
4044 G1ParScanThreadStateSet* _pss;
4045 RefToScanQueueSet* _queues;
4046 G1RootProcessor* _root_processor;
4047 ParallelTaskTerminator _terminator;
4048 uint _n_workers;
4049
4050 public:
4051 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4052 : AbstractGangTask("G1 collection"),
4053 _g1h(g1h),
4054 _pss(per_thread_states),
4055 _queues(task_queues),
4056 _root_processor(root_processor),
4057 _terminator(n_workers, _queues),
4058 _n_workers(n_workers)
4059 {}
4060
4061 void work(uint worker_id) {
4062 if (worker_id >= _n_workers) return; // no work needed this round
4063
4064 double start_sec = os::elapsedTime();
4065 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4066
4067 {
4068 ResourceMark rm;
4069 HandleMark hm;
4070
4071 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4072
4073 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4074 pss->set_ref_processor(rp);
4075
4076 double start_strong_roots_sec = os::elapsedTime();
4077
4078 _root_processor->evacuate_roots(pss->closures(), worker_id);
4079
4080 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4081
4082 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4083 // treating the nmethods visited to act as roots for concurrent marking.
4084 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4085 // objects copied by the current evacuation.
4086 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4087 pss->closures()->weak_codeblobs(),
4088 worker_id);
4089
4090 _pss->add_cards_scanned(worker_id, cards_scanned);
4091
4092 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4093
4094 double term_sec = 0.0;
4095 size_t evac_term_attempts = 0;
4096 {
4097 double start = os::elapsedTime();
4098 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4099 evac.do_void();
4100
4101 evac_term_attempts = evac.term_attempts();
4102 term_sec = evac.term_time();
4103 double elapsed_sec = os::elapsedTime() - start;
4104 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4105 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4106 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4107 }
4108
4109 assert(pss->queue_is_empty(), "should be empty");
4110
4111 if (log_is_enabled(Debug, gc, task, stats)) {
4112 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4113 size_t lab_waste;
4114 size_t lab_undo_waste;
4115 pss->waste(lab_waste, lab_undo_waste);
4116 _g1h->print_termination_stats(worker_id,
4117 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4118 strong_roots_sec * 1000.0, /* strong roots time */
4119 term_sec * 1000.0, /* evac term time */
4120 evac_term_attempts, /* evac term attempts */
4121 lab_waste, /* alloc buffer waste */
4122 lab_undo_waste /* undo waste */
4123 );
4124 }
4125
4126 // Close the inner scope so that the ResourceMark and HandleMark
4127 // destructors are executed here and are included as part of the
4128 // "GC Worker Time".
4129 }
4130 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4131 }
4132 };
4133
4134 void G1CollectedHeap::print_termination_stats_hdr() {
4135 log_debug(gc, task, stats)("GC Termination Stats");
4136 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4137 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
4138 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4139 }
4140
4141 void G1CollectedHeap::print_termination_stats(uint worker_id,
4142 double elapsed_ms,
4143 double strong_roots_ms,
4144 double term_ms,
4145 size_t term_attempts,
4146 size_t alloc_buffer_waste,
4147 size_t undo_waste) const {
4148 log_debug(gc, task, stats)
4149 ("%3d %9.2f %9.2f %6.2f "
4150 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4151 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4152 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4153 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4154 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4155 alloc_buffer_waste * HeapWordSize / K,
4156 undo_waste * HeapWordSize / K);
4157 }
4158
4159 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4160 private:
4161 BoolObjectClosure* _is_alive;
4162 int _initial_string_table_size;
4163 int _initial_symbol_table_size;
4164
4165 bool _process_strings;
4166 int _strings_processed;
4167 int _strings_removed;
4168
4169 bool _process_symbols;
4170 int _symbols_processed;
4171 int _symbols_removed;
4172
4173 public:
4174 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4175 AbstractGangTask("String/Symbol Unlinking"),
4176 _is_alive(is_alive),
4177 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4178 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4179
4180 _initial_string_table_size = StringTable::the_table()->table_size();
4181 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4182 if (process_strings) {
4183 StringTable::clear_parallel_claimed_index();
4184 }
4185 if (process_symbols) {
4186 SymbolTable::clear_parallel_claimed_index();
4187 }
4188 }
4189
4190 ~G1StringSymbolTableUnlinkTask() {
4191 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4192 "claim value %d after unlink less than initial string table size %d",
4193 StringTable::parallel_claimed_index(), _initial_string_table_size);
4194 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4195 "claim value %d after unlink less than initial symbol table size %d",
4196 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4197
4198 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
4199 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4200 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4201 strings_processed(), strings_removed(),
4202 symbols_processed(), symbols_removed());
4203 }
4204
4205 void work(uint worker_id) {
4206 int strings_processed = 0;
4207 int strings_removed = 0;
4208 int symbols_processed = 0;
4209 int symbols_removed = 0;
4210 if (_process_strings) {
4211 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4212 Atomic::add(strings_processed, &_strings_processed);
4213 Atomic::add(strings_removed, &_strings_removed);
4214 }
4215 if (_process_symbols) {
4216 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4217 Atomic::add(symbols_processed, &_symbols_processed);
4218 Atomic::add(symbols_removed, &_symbols_removed);
4219 }
4220 }
4221
4222 size_t strings_processed() const { return (size_t)_strings_processed; }
4223 size_t strings_removed() const { return (size_t)_strings_removed; }
4224
4225 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4226 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4227 };
4228
4229 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4230 private:
4231 static Monitor* _lock;
4232
4233 BoolObjectClosure* const _is_alive;
4234 const bool _unloading_occurred;
4235 const uint _num_workers;
4236
4237 // Variables used to claim nmethods.
4238 nmethod* _first_nmethod;
4239 volatile nmethod* _claimed_nmethod;
4240
4241 // The list of nmethods that need to be processed by the second pass.
4242 volatile nmethod* _postponed_list;
4243 volatile uint _num_entered_barrier;
4244
4245 public:
4246 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4247 _is_alive(is_alive),
4248 _unloading_occurred(unloading_occurred),
4249 _num_workers(num_workers),
4250 _first_nmethod(NULL),
4251 _claimed_nmethod(NULL),
4252 _postponed_list(NULL),
4253 _num_entered_barrier(0)
4254 {
4255 nmethod::increase_unloading_clock();
4256 // Get first alive nmethod
4257 NMethodIterator iter = NMethodIterator();
4258 if(iter.next_alive()) {
4259 _first_nmethod = iter.method();
4260 }
4261 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4262 }
4263
4264 ~G1CodeCacheUnloadingTask() {
4265 CodeCache::verify_clean_inline_caches();
4266
4267 CodeCache::set_needs_cache_clean(false);
4268 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4269
4270 CodeCache::verify_icholder_relocations();
4271 }
4272
4273 private:
4274 void add_to_postponed_list(nmethod* nm) {
4275 nmethod* old;
4276 do {
4277 old = (nmethod*)_postponed_list;
4278 nm->set_unloading_next(old);
4279 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4280 }
4281
4282 void clean_nmethod(nmethod* nm) {
4283 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4284
4285 if (postponed) {
4286 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4287 add_to_postponed_list(nm);
4288 }
4289
4290 // Mark that this thread has been cleaned/unloaded.
4291 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4292 nm->set_unloading_clock(nmethod::global_unloading_clock());
4293 }
4294
4295 void clean_nmethod_postponed(nmethod* nm) {
4296 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4297 }
4298
4299 static const int MaxClaimNmethods = 16;
4300
4301 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4302 nmethod* first;
4303 NMethodIterator last;
4304
4305 do {
4306 *num_claimed_nmethods = 0;
4307
4308 first = (nmethod*)_claimed_nmethod;
4309 last = NMethodIterator(first);
4310
4311 if (first != NULL) {
4312
4313 for (int i = 0; i < MaxClaimNmethods; i++) {
4314 if (!last.next_alive()) {
4315 break;
4316 }
4317 claimed_nmethods[i] = last.method();
4318 (*num_claimed_nmethods)++;
4319 }
4320 }
4321
4322 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4323 }
4324
4325 nmethod* claim_postponed_nmethod() {
4326 nmethod* claim;
4327 nmethod* next;
4328
4329 do {
4330 claim = (nmethod*)_postponed_list;
4331 if (claim == NULL) {
4332 return NULL;
4333 }
4334
4335 next = claim->unloading_next();
4336
4337 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4338
4339 return claim;
4340 }
4341
4342 public:
4343 // Mark that we're done with the first pass of nmethod cleaning.
4344 void barrier_mark(uint worker_id) {
4345 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4346 _num_entered_barrier++;
4347 if (_num_entered_barrier == _num_workers) {
4348 ml.notify_all();
4349 }
4350 }
4351
4352 // See if we have to wait for the other workers to
4353 // finish their first-pass nmethod cleaning work.
4354 void barrier_wait(uint worker_id) {
4355 if (_num_entered_barrier < _num_workers) {
4356 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4357 while (_num_entered_barrier < _num_workers) {
4358 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4359 }
4360 }
4361 }
4362
4363 // Cleaning and unloading of nmethods. Some work has to be postponed
4364 // to the second pass, when we know which nmethods survive.
4365 void work_first_pass(uint worker_id) {
4366 // The first nmethods is claimed by the first worker.
4367 if (worker_id == 0 && _first_nmethod != NULL) {
4368 clean_nmethod(_first_nmethod);
4369 _first_nmethod = NULL;
4370 }
4371
4372 int num_claimed_nmethods;
4373 nmethod* claimed_nmethods[MaxClaimNmethods];
4374
4375 while (true) {
4376 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4377
4378 if (num_claimed_nmethods == 0) {
4379 break;
4380 }
4381
4382 for (int i = 0; i < num_claimed_nmethods; i++) {
4383 clean_nmethod(claimed_nmethods[i]);
4384 }
4385 }
4386 }
4387
4388 void work_second_pass(uint worker_id) {
4389 nmethod* nm;
4390 // Take care of postponed nmethods.
4391 while ((nm = claim_postponed_nmethod()) != NULL) {
4392 clean_nmethod_postponed(nm);
4393 }
4394 }
4395 };
4396
4397 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4398
4399 class G1KlassCleaningTask : public StackObj {
4400 BoolObjectClosure* _is_alive;
4401 volatile jint _clean_klass_tree_claimed;
4402 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4403
4404 public:
4405 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4406 _is_alive(is_alive),
4407 _clean_klass_tree_claimed(0),
4408 _klass_iterator() {
4409 }
4410
4411 private:
4412 bool claim_clean_klass_tree_task() {
4413 if (_clean_klass_tree_claimed) {
4414 return false;
4415 }
4416
4417 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4418 }
4419
4420 InstanceKlass* claim_next_klass() {
4421 Klass* klass;
4422 do {
4423 klass =_klass_iterator.next_klass();
4424 } while (klass != NULL && !klass->is_instance_klass());
4425
4426 // this can be null so don't call InstanceKlass::cast
4427 return static_cast<InstanceKlass*>(klass);
4428 }
4429
4430 public:
4431
4432 void clean_klass(InstanceKlass* ik) {
4433 ik->clean_weak_instanceklass_links(_is_alive);
4434 }
4435
4436 void work() {
4437 ResourceMark rm;
4438
4439 // One worker will clean the subklass/sibling klass tree.
4440 if (claim_clean_klass_tree_task()) {
4441 Klass::clean_subklass_tree(_is_alive);
4442 }
4443
4444 // All workers will help cleaning the classes,
4445 InstanceKlass* klass;
4446 while ((klass = claim_next_klass()) != NULL) {
4447 clean_klass(klass);
4448 }
4449 }
4450 };
4451
4452 // To minimize the remark pause times, the tasks below are done in parallel.
4453 class G1ParallelCleaningTask : public AbstractGangTask {
4454 private:
4455 G1StringSymbolTableUnlinkTask _string_symbol_task;
4456 G1CodeCacheUnloadingTask _code_cache_task;
4457 G1KlassCleaningTask _klass_cleaning_task;
4458
4459 public:
4460 // The constructor is run in the VMThread.
4461 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4462 AbstractGangTask("Parallel Cleaning"),
4463 _string_symbol_task(is_alive, process_strings, process_symbols),
4464 _code_cache_task(num_workers, is_alive, unloading_occurred),
4465 _klass_cleaning_task(is_alive) {
4466 }
4467
4468 // The parallel work done by all worker threads.
4469 void work(uint worker_id) {
4470 // Do first pass of code cache cleaning.
4471 _code_cache_task.work_first_pass(worker_id);
4472
4473 // Let the threads mark that the first pass is done.
4474 _code_cache_task.barrier_mark(worker_id);
4475
4476 // Clean the Strings and Symbols.
4477 _string_symbol_task.work(worker_id);
4478
4479 // Wait for all workers to finish the first code cache cleaning pass.
4480 _code_cache_task.barrier_wait(worker_id);
4481
4482 // Do the second code cache cleaning work, which realize on
4483 // the liveness information gathered during the first pass.
4484 _code_cache_task.work_second_pass(worker_id);
4485
4486 // Clean all klasses that were not unloaded.
4487 _klass_cleaning_task.work();
4488 }
4489 };
4490
4491
4492 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4493 bool process_strings,
4494 bool process_symbols,
4495 bool class_unloading_occurred) {
4496 uint n_workers = workers()->active_workers();
4497
4498 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4499 n_workers, class_unloading_occurred);
4500 workers()->run_task(&g1_unlink_task);
4501 }
4502
4503 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4504 bool process_strings, bool process_symbols) {
4505 {
4506 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4507 workers()->run_task(&g1_unlink_task);
4508 }
4509
4510 if (G1StringDedup::is_enabled()) {
4511 G1StringDedup::unlink(is_alive);
4512 }
4513 }
4514
4515 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4516 private:
4517 DirtyCardQueueSet* _queue;
4518 G1CollectedHeap* _g1h;
4519 public:
4520 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4521 _queue(queue), _g1h(g1h) { }
4522
4523 virtual void work(uint worker_id) {
4524 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4525 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4526
4527 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4528 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4529
4530 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4531 }
4532 };
4533
4534 void G1CollectedHeap::redirty_logged_cards() {
4535 double redirty_logged_cards_start = os::elapsedTime();
4536
4537 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4538 dirty_card_queue_set().reset_for_par_iteration();
4539 workers()->run_task(&redirty_task);
4540
4541 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4542 dcq.merge_bufferlists(&dirty_card_queue_set());
4543 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4544
4545 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4546 }
4547
4548 // Weak Reference Processing support
4549
4550 // An always "is_alive" closure that is used to preserve referents.
4551 // If the object is non-null then it's alive. Used in the preservation
4552 // of referent objects that are pointed to by reference objects
4553 // discovered by the CM ref processor.
4554 class G1AlwaysAliveClosure: public BoolObjectClosure {
4555 G1CollectedHeap* _g1;
4556 public:
4557 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4558 bool do_object_b(oop p) {
4559 if (p != NULL) {
4560 return true;
4561 }
4562 return false;
4563 }
4564 };
4565
4566 bool G1STWIsAliveClosure::do_object_b(oop p) {
4567 // An object is reachable if it is outside the collection set,
4568 // or is inside and copied.
4569 return !_g1->is_in_cset(p) || p->is_forwarded();
4570 }
4571
4572 // Non Copying Keep Alive closure
4573 class G1KeepAliveClosure: public OopClosure {
4574 G1CollectedHeap* _g1;
4575 public:
4576 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4577 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4578 void do_oop(oop* p) {
4579 oop obj = *p;
4580 assert(obj != NULL, "the caller should have filtered out NULL values");
4581
4582 const InCSetState cset_state = _g1->in_cset_state(obj);
4583 if (!cset_state.is_in_cset_or_humongous()) {
4584 return;
4585 }
4586 if (cset_state.is_in_cset()) {
4587 assert( obj->is_forwarded(), "invariant" );
4588 *p = obj->forwardee();
4589 } else {
4590 assert(!obj->is_forwarded(), "invariant" );
4591 assert(cset_state.is_humongous(),
4592 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4593 _g1->set_humongous_is_live(obj);
4594 }
4595 }
4596 };
4597
4598 // Copying Keep Alive closure - can be called from both
4599 // serial and parallel code as long as different worker
4600 // threads utilize different G1ParScanThreadState instances
4601 // and different queues.
4602
4603 class G1CopyingKeepAliveClosure: public OopClosure {
4604 G1CollectedHeap* _g1h;
4605 OopClosure* _copy_non_heap_obj_cl;
4606 G1ParScanThreadState* _par_scan_state;
4607
4608 public:
4609 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4610 OopClosure* non_heap_obj_cl,
4611 G1ParScanThreadState* pss):
4612 _g1h(g1h),
4613 _copy_non_heap_obj_cl(non_heap_obj_cl),
4614 _par_scan_state(pss)
4615 {}
4616
4617 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4618 virtual void do_oop( oop* p) { do_oop_work(p); }
4619
4620 template <class T> void do_oop_work(T* p) {
4621 oop obj = oopDesc::load_decode_heap_oop(p);
4622
4623 if (_g1h->is_in_cset_or_humongous(obj)) {
4624 // If the referent object has been forwarded (either copied
4625 // to a new location or to itself in the event of an
4626 // evacuation failure) then we need to update the reference
4627 // field and, if both reference and referent are in the G1
4628 // heap, update the RSet for the referent.
4629 //
4630 // If the referent has not been forwarded then we have to keep
4631 // it alive by policy. Therefore we have copy the referent.
4632 //
4633 // If the reference field is in the G1 heap then we can push
4634 // on the PSS queue. When the queue is drained (after each
4635 // phase of reference processing) the object and it's followers
4636 // will be copied, the reference field set to point to the
4637 // new location, and the RSet updated. Otherwise we need to
4638 // use the the non-heap or metadata closures directly to copy
4639 // the referent object and update the pointer, while avoiding
4640 // updating the RSet.
4641
4642 if (_g1h->is_in_g1_reserved(p)) {
4643 _par_scan_state->push_on_queue(p);
4644 } else {
4645 assert(!Metaspace::contains((const void*)p),
4646 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4647 _copy_non_heap_obj_cl->do_oop(p);
4648 }
4649 }
4650 }
4651 };
4652
4653 // Serial drain queue closure. Called as the 'complete_gc'
4654 // closure for each discovered list in some of the
4655 // reference processing phases.
4656
4657 class G1STWDrainQueueClosure: public VoidClosure {
4658 protected:
4659 G1CollectedHeap* _g1h;
4660 G1ParScanThreadState* _par_scan_state;
4661
4662 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4663
4664 public:
4665 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4666 _g1h(g1h),
4667 _par_scan_state(pss)
4668 { }
4669
4670 void do_void() {
4671 G1ParScanThreadState* const pss = par_scan_state();
4672 pss->trim_queue();
4673 }
4674 };
4675
4676 // Parallel Reference Processing closures
4677
4678 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4679 // processing during G1 evacuation pauses.
4680
4681 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4682 private:
4683 G1CollectedHeap* _g1h;
4684 G1ParScanThreadStateSet* _pss;
4685 RefToScanQueueSet* _queues;
4686 WorkGang* _workers;
4687 uint _active_workers;
4688
4689 public:
4690 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4691 G1ParScanThreadStateSet* per_thread_states,
4692 WorkGang* workers,
4693 RefToScanQueueSet *task_queues,
4694 uint n_workers) :
4695 _g1h(g1h),
4696 _pss(per_thread_states),
4697 _queues(task_queues),
4698 _workers(workers),
4699 _active_workers(n_workers)
4700 {
4701 assert(n_workers > 0, "shouldn't call this otherwise");
4702 }
4703
4704 // Executes the given task using concurrent marking worker threads.
4705 virtual void execute(ProcessTask& task);
4706 virtual void execute(EnqueueTask& task);
4707 };
4708
4709 // Gang task for possibly parallel reference processing
4710
4711 class G1STWRefProcTaskProxy: public AbstractGangTask {
4712 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4713 ProcessTask& _proc_task;
4714 G1CollectedHeap* _g1h;
4715 G1ParScanThreadStateSet* _pss;
4716 RefToScanQueueSet* _task_queues;
4717 ParallelTaskTerminator* _terminator;
4718
4719 public:
4720 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4721 G1CollectedHeap* g1h,
4722 G1ParScanThreadStateSet* per_thread_states,
4723 RefToScanQueueSet *task_queues,
4724 ParallelTaskTerminator* terminator) :
4725 AbstractGangTask("Process reference objects in parallel"),
4726 _proc_task(proc_task),
4727 _g1h(g1h),
4728 _pss(per_thread_states),
4729 _task_queues(task_queues),
4730 _terminator(terminator)
4731 {}
4732
4733 virtual void work(uint worker_id) {
4734 // The reference processing task executed by a single worker.
4735 ResourceMark rm;
4736 HandleMark hm;
4737
4738 G1STWIsAliveClosure is_alive(_g1h);
4739
4740 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4741 pss->set_ref_processor(NULL);
4742
4743 // Keep alive closure.
4744 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4745
4746 // Complete GC closure
4747 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4748
4749 // Call the reference processing task's work routine.
4750 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4751
4752 // Note we cannot assert that the refs array is empty here as not all
4753 // of the processing tasks (specifically phase2 - pp2_work) execute
4754 // the complete_gc closure (which ordinarily would drain the queue) so
4755 // the queue may not be empty.
4756 }
4757 };
4758
4759 // Driver routine for parallel reference processing.
4760 // Creates an instance of the ref processing gang
4761 // task and has the worker threads execute it.
4762 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4763 assert(_workers != NULL, "Need parallel worker threads.");
4764
4765 ParallelTaskTerminator terminator(_active_workers, _queues);
4766 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4767
4768 _workers->run_task(&proc_task_proxy);
4769 }
4770
4771 // Gang task for parallel reference enqueueing.
4772
4773 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4774 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4775 EnqueueTask& _enq_task;
4776
4777 public:
4778 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4779 AbstractGangTask("Enqueue reference objects in parallel"),
4780 _enq_task(enq_task)
4781 { }
4782
4783 virtual void work(uint worker_id) {
4784 _enq_task.work(worker_id);
4785 }
4786 };
4787
4788 // Driver routine for parallel reference enqueueing.
4789 // Creates an instance of the ref enqueueing gang
4790 // task and has the worker threads execute it.
4791
4792 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4793 assert(_workers != NULL, "Need parallel worker threads.");
4794
4795 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4796
4797 _workers->run_task(&enq_task_proxy);
4798 }
4799
4800 // End of weak reference support closures
4801
4802 // Abstract task used to preserve (i.e. copy) any referent objects
4803 // that are in the collection set and are pointed to by reference
4804 // objects discovered by the CM ref processor.
4805
4806 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4807 protected:
4808 G1CollectedHeap* _g1h;
4809 G1ParScanThreadStateSet* _pss;
4810 RefToScanQueueSet* _queues;
4811 ParallelTaskTerminator _terminator;
4812 uint _n_workers;
4813
4814 public:
4815 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4816 AbstractGangTask("ParPreserveCMReferents"),
4817 _g1h(g1h),
4818 _pss(per_thread_states),
4819 _queues(task_queues),
4820 _terminator(workers, _queues),
4821 _n_workers(workers)
4822 { }
4823
4824 void work(uint worker_id) {
4825 ResourceMark rm;
4826 HandleMark hm;
4827
4828 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4829 pss->set_ref_processor(NULL);
4830 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4831
4832 // Is alive closure
4833 G1AlwaysAliveClosure always_alive(_g1h);
4834
4835 // Copying keep alive closure. Applied to referent objects that need
4836 // to be copied.
4837 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4838
4839 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4840
4841 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4842 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4843
4844 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4845 // So this must be true - but assert just in case someone decides to
4846 // change the worker ids.
4847 assert(worker_id < limit, "sanity");
4848 assert(!rp->discovery_is_atomic(), "check this code");
4849
4850 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4851 for (uint idx = worker_id; idx < limit; idx += stride) {
4852 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4853
4854 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4855 while (iter.has_next()) {
4856 // Since discovery is not atomic for the CM ref processor, we
4857 // can see some null referent objects.
4858 iter.load_ptrs(DEBUG_ONLY(true));
4859 oop ref = iter.obj();
4860
4861 // This will filter nulls.
4862 if (iter.is_referent_alive()) {
4863 iter.make_referent_alive();
4864 }
4865 iter.move_to_next();
4866 }
4867 }
4868
4869 // Drain the queue - which may cause stealing
4870 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4871 drain_queue.do_void();
4872 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4873 assert(pss->queue_is_empty(), "should be");
4874 }
4875 };
4876
4877 void G1CollectedHeap::process_weak_jni_handles() {
4878 double ref_proc_start = os::elapsedTime();
4879
4880 G1STWIsAliveClosure is_alive(this);
4881 G1KeepAliveClosure keep_alive(this);
4882 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4883
4884 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4885 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4886 }
4887
4888 // Weak Reference processing during an evacuation pause (part 1).
4889 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4890 double ref_proc_start = os::elapsedTime();
4891
4892 ReferenceProcessor* rp = _ref_processor_stw;
4893 assert(rp->discovery_enabled(), "should have been enabled");
4894
4895 // Any reference objects, in the collection set, that were 'discovered'
4896 // by the CM ref processor should have already been copied (either by
4897 // applying the external root copy closure to the discovered lists, or
4898 // by following an RSet entry).
4899 //
4900 // But some of the referents, that are in the collection set, that these
4901 // reference objects point to may not have been copied: the STW ref
4902 // processor would have seen that the reference object had already
4903 // been 'discovered' and would have skipped discovering the reference,
4904 // but would not have treated the reference object as a regular oop.
4905 // As a result the copy closure would not have been applied to the
4906 // referent object.
4907 //
4908 // We need to explicitly copy these referent objects - the references
4909 // will be processed at the end of remarking.
4910 //
4911 // We also need to do this copying before we process the reference
4912 // objects discovered by the STW ref processor in case one of these
4913 // referents points to another object which is also referenced by an
4914 // object discovered by the STW ref processor.
4915
4916 uint no_of_gc_workers = workers()->active_workers();
4917
4918 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4919 per_thread_states,
4920 no_of_gc_workers,
4921 _task_queues);
4922
4923 workers()->run_task(&keep_cm_referents);
4924
4925 // Closure to test whether a referent is alive.
4926 G1STWIsAliveClosure is_alive(this);
4927
4928 // Even when parallel reference processing is enabled, the processing
4929 // of JNI refs is serial and performed serially by the current thread
4930 // rather than by a worker. The following PSS will be used for processing
4931 // JNI refs.
4932
4933 // Use only a single queue for this PSS.
4934 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4935 pss->set_ref_processor(NULL);
4936 assert(pss->queue_is_empty(), "pre-condition");
4937
4938 // Keep alive closure.
4939 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4940
4941 // Serial Complete GC closure
4942 G1STWDrainQueueClosure drain_queue(this, pss);
4943
4944 // Setup the soft refs policy...
4945 rp->setup_policy(false);
4946
4947 ReferenceProcessorStats stats;
4948 if (!rp->processing_is_mt()) {
4949 // Serial reference processing...
4950 stats = rp->process_discovered_references(&is_alive,
4951 &keep_alive,
4952 &drain_queue,
4953 NULL,
4954 _gc_timer_stw);
4955 } else {
4956 // Parallel reference processing
4957 assert(rp->num_q() == no_of_gc_workers, "sanity");
4958 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4959
4960 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4961 stats = rp->process_discovered_references(&is_alive,
4962 &keep_alive,
4963 &drain_queue,
4964 &par_task_executor,
4965 _gc_timer_stw);
4966 }
4967
4968 _gc_tracer_stw->report_gc_reference_stats(stats);
4969
4970 // We have completed copying any necessary live referent objects.
4971 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4972
4973 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4974 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4975 }
4976
4977 // Weak Reference processing during an evacuation pause (part 2).
4978 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4979 double ref_enq_start = os::elapsedTime();
4980
4981 ReferenceProcessor* rp = _ref_processor_stw;
4982 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4983
4984 // Now enqueue any remaining on the discovered lists on to
4985 // the pending list.
4986 if (!rp->processing_is_mt()) {
4987 // Serial reference processing...
4988 rp->enqueue_discovered_references();
4989 } else {
4990 // Parallel reference enqueueing
4991
4992 uint n_workers = workers()->active_workers();
4993
4994 assert(rp->num_q() == n_workers, "sanity");
4995 assert(n_workers <= rp->max_num_q(), "sanity");
4996
4997 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4998 rp->enqueue_discovered_references(&par_task_executor);
4999 }
5000
5001 rp->verify_no_references_recorded();
5002 assert(!rp->discovery_enabled(), "should have been disabled");
5003
5004 // FIXME
5005 // CM's reference processing also cleans up the string and symbol tables.
5006 // Should we do that here also? We could, but it is a serial operation
5007 // and could significantly increase the pause time.
5008
5009 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5010 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5011 }
5012
5013 void G1CollectedHeap::pre_evacuate_collection_set() {
5014 _expand_heap_after_alloc_failure = true;
5015 _evacuation_failed = false;
5016
5017 // Disable the hot card cache.
5018 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5019 hot_card_cache->reset_hot_cache_claimed_index();
5020 hot_card_cache->set_use_cache(false);
5021
5022 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5023 }
5024
5025 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5026 // Should G1EvacuationFailureALot be in effect for this GC?
5027 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5028
5029 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5030 double start_par_time_sec = os::elapsedTime();
5031 double end_par_time_sec;
5032
5033 {
5034 const uint n_workers = workers()->active_workers();
5035 G1RootProcessor root_processor(this, n_workers);
5036 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5037 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5038 if (collector_state()->during_initial_mark_pause()) {
5039 ClassLoaderDataGraph::clear_claimed_marks();
5040 }
5041
5042 print_termination_stats_hdr();
5043
5044 workers()->run_task(&g1_par_task);
5045 end_par_time_sec = os::elapsedTime();
5046
5047 // Closing the inner scope will execute the destructor
5048 // for the G1RootProcessor object. We record the current
5049 // elapsed time before closing the scope so that time
5050 // taken for the destructor is NOT included in the
5051 // reported parallel time.
5052 }
5053
5054 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5055
5056 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5057 phase_times->record_par_time(par_time_ms);
5058
5059 double code_root_fixup_time_ms =
5060 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5061 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5062 }
5063
5064 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5065 // Process any discovered reference objects - we have
5066 // to do this _before_ we retire the GC alloc regions
5067 // as we may have to copy some 'reachable' referent
5068 // objects (and their reachable sub-graphs) that were
5069 // not copied during the pause.
5070 if (g1_policy()->should_process_references()) {
5071 process_discovered_references(per_thread_states);
5072 } else {
5073 ref_processor_stw()->verify_no_references_recorded();
5074 process_weak_jni_handles();
5075 }
5076
5077 if (G1StringDedup::is_enabled()) {
5078 double fixup_start = os::elapsedTime();
5079
5080 G1STWIsAliveClosure is_alive(this);
5081 G1KeepAliveClosure keep_alive(this);
5082 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
5083
5084 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5085 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
5086 }
5087
5088 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5089
5090 if (evacuation_failed()) {
5091 restore_after_evac_failure();
5092
5093 // Reset the G1EvacuationFailureALot counters and flags
5094 // Note: the values are reset only when an actual
5095 // evacuation failure occurs.
5096 NOT_PRODUCT(reset_evacuation_should_fail();)
5097 }
5098
5099 // Enqueue any remaining references remaining on the STW
5100 // reference processor's discovered lists. We need to do
5101 // this after the card table is cleaned (and verified) as
5102 // the act of enqueueing entries on to the pending list
5103 // will log these updates (and dirty their associated
5104 // cards). We need these updates logged to update any
5105 // RSets.
5106 if (g1_policy()->should_process_references()) {
5107 enqueue_discovered_references(per_thread_states);
5108 } else {
5109 g1_policy()->phase_times()->record_ref_enq_time(0);
5110 }
5111
5112 _allocator->release_gc_alloc_regions(evacuation_info);
5113
5114 per_thread_states->flush();
5115
5116 record_obj_copy_mem_stats();
5117
5118 _survivor_evac_stats.adjust_desired_plab_sz();
5119 _old_evac_stats.adjust_desired_plab_sz();
5120
5121 // Reset and re-enable the hot card cache.
5122 // Note the counts for the cards in the regions in the
5123 // collection set are reset when the collection set is freed.
5124 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5125 hot_card_cache->reset_hot_cache();
5126 hot_card_cache->set_use_cache(true);
5127
5128 purge_code_root_memory();
5129
5130 redirty_logged_cards();
5131 #if defined(COMPILER2) || INCLUDE_JVMCI
5132 DerivedPointerTable::update_pointers();
5133 #endif
5134 }
5135
5136 void G1CollectedHeap::record_obj_copy_mem_stats() {
5137 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
5138
5139 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5140 create_g1_evac_summary(&_old_evac_stats));
5141 }
5142
5143 void G1CollectedHeap::free_region(HeapRegion* hr,
5144 FreeRegionList* free_list,
5145 bool par,
5146 bool locked) {
5147 assert(!hr->is_free(), "the region should not be free");
5148 assert(!hr->is_empty(), "the region should not be empty");
5149 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5150 assert(free_list != NULL, "pre-condition");
5151
5152 if (G1VerifyBitmaps) {
5153 MemRegion mr(hr->bottom(), hr->end());
5154 concurrent_mark()->clearRangePrevBitmap(mr);
5155 }
5156
5157 // Clear the card counts for this region.
5158 // Note: we only need to do this if the region is not young
5159 // (since we don't refine cards in young regions).
5160 if (!hr->is_young()) {
5161 _cg1r->hot_card_cache()->reset_card_counts(hr);
5162 }
5163 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5164 free_list->add_ordered(hr);
5165 }
5166
5167 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5168 FreeRegionList* free_list,
5169 bool par) {
5170 assert(hr->is_humongous(), "this is only for humongous regions");
5171 assert(free_list != NULL, "pre-condition");
5172 hr->clear_humongous();
5173 free_region(hr, free_list, par);
5174 }
5175
5176 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
5177 const uint humongous_regions_removed) {
5178 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
5179 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5180 _old_set.bulk_remove(old_regions_removed);
5181 _humongous_set.bulk_remove(humongous_regions_removed);
5182 }
5183
5184 }
5185
5186 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5187 assert(list != NULL, "list can't be null");
5188 if (!list->is_empty()) {
5189 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5190 _hrm.insert_list_into_free_list(list);
5191 }
5192 }
5193
5194 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5195 decrease_used(bytes);
5196 }
5197
5198 class G1ParCleanupCTTask : public AbstractGangTask {
5199 G1SATBCardTableModRefBS* _ct_bs;
5200 G1CollectedHeap* _g1h;
5201 HeapRegion* volatile _su_head;
5202 public:
5203 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5204 G1CollectedHeap* g1h) :
5205 AbstractGangTask("G1 Par Cleanup CT Task"),
5206 _ct_bs(ct_bs), _g1h(g1h) { }
5207
5208 void work(uint worker_id) {
5209 HeapRegion* r;
5210 while (r = _g1h->pop_dirty_cards_region()) {
5211 clear_cards(r);
5212 }
5213 }
5214
5215 void clear_cards(HeapRegion* r) {
5216 // Cards of the survivors should have already been dirtied.
5217 if (!r->is_survivor()) {
5218 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5219 }
5220 }
5221 };
5222
5223 #ifndef PRODUCT
5224 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5225 G1CollectedHeap* _g1h;
5226 G1SATBCardTableModRefBS* _ct_bs;
5227 public:
5228 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5229 : _g1h(g1h), _ct_bs(ct_bs) { }
5230 virtual bool doHeapRegion(HeapRegion* r) {
5231 if (r->is_survivor()) {
5232 _g1h->verify_dirty_region(r);
5233 } else {
5234 _g1h->verify_not_dirty_region(r);
5235 }
5236 return false;
5237 }
5238 };
5239
5240 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5241 // All of the region should be clean.
5242 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5243 MemRegion mr(hr->bottom(), hr->end());
5244 ct_bs->verify_not_dirty_region(mr);
5245 }
5246
5247 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5248 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5249 // dirty allocated blocks as they allocate them. The thread that
5250 // retires each region and replaces it with a new one will do a
5251 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5252 // not dirty that area (one less thing to have to do while holding
5253 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5254 // is dirty.
5255 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5256 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5257 if (hr->is_young()) {
5258 ct_bs->verify_g1_young_region(mr);
5259 } else {
5260 ct_bs->verify_dirty_region(mr);
5261 }
5262 }
5263
5264 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5265 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5266 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5267 verify_dirty_region(hr);
5268 }
5269 }
5270
5271 void G1CollectedHeap::verify_dirty_young_regions() {
5272 verify_dirty_young_list(_young_list->first_region());
5273 }
5274
5275 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5276 HeapWord* tams, HeapWord* end) {
5277 guarantee(tams <= end,
5278 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5279 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5280 if (result < end) {
5281 log_info(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
5282 log_info(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
5283 return false;
5284 }
5285 return true;
5286 }
5287
5288 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5289 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5290 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5291
5292 HeapWord* bottom = hr->bottom();
5293 HeapWord* ptams = hr->prev_top_at_mark_start();
5294 HeapWord* ntams = hr->next_top_at_mark_start();
5295 HeapWord* end = hr->end();
5296
5297 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5298
5299 bool res_n = true;
5300 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5301 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5302 // if we happen to be in that state.
5303 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5304 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5305 }
5306 if (!res_p || !res_n) {
5307 log_info(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
5308 log_info(gc, verify)("#### Caller: %s", caller);
5309 return false;
5310 }
5311 return true;
5312 }
5313
5314 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5315 if (!G1VerifyBitmaps) return;
5316
5317 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5318 }
5319
5320 class G1VerifyBitmapClosure : public HeapRegionClosure {
5321 private:
5322 const char* _caller;
5323 G1CollectedHeap* _g1h;
5324 bool _failures;
5325
5326 public:
5327 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5328 _caller(caller), _g1h(g1h), _failures(false) { }
5329
5330 bool failures() { return _failures; }
5331
5332 virtual bool doHeapRegion(HeapRegion* hr) {
5333 bool result = _g1h->verify_bitmaps(_caller, hr);
5334 if (!result) {
5335 _failures = true;
5336 }
5337 return false;
5338 }
5339 };
5340
5341 void G1CollectedHeap::check_bitmaps(const char* caller) {
5342 if (!G1VerifyBitmaps) return;
5343
5344 G1VerifyBitmapClosure cl(caller, this);
5345 heap_region_iterate(&cl);
5346 guarantee(!cl.failures(), "bitmap verification");
5347 }
5348
5349 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5350 private:
5351 bool _failures;
5352 public:
5353 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5354
5355 virtual bool doHeapRegion(HeapRegion* hr) {
5356 uint i = hr->hrm_index();
5357 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5358 if (hr->is_humongous()) {
5359 if (hr->in_collection_set()) {
5360 log_info(gc, verify)("## humongous region %u in CSet", i);
5361 _failures = true;
5362 return true;
5363 }
5364 if (cset_state.is_in_cset()) {
5365 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for humongous region %u", cset_state.value(), i);
5366 _failures = true;
5367 return true;
5368 }
5369 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5370 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for continues humongous region %u", cset_state.value(), i);
5371 _failures = true;
5372 return true;
5373 }
5374 } else {
5375 if (cset_state.is_humongous()) {
5376 log_info(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for non-humongous region %u", cset_state.value(), i);
5377 _failures = true;
5378 return true;
5379 }
5380 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5381 log_info(gc, verify)("## in CSet %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5382 hr->in_collection_set(), cset_state.value(), i);
5383 _failures = true;
5384 return true;
5385 }
5386 if (cset_state.is_in_cset()) {
5387 if (hr->is_young() != (cset_state.is_young())) {
5388 log_info(gc, verify)("## is_young %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5389 hr->is_young(), cset_state.value(), i);
5390 _failures = true;
5391 return true;
5392 }
5393 if (hr->is_old() != (cset_state.is_old())) {
5394 log_info(gc, verify)("## is_old %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
5395 hr->is_old(), cset_state.value(), i);
5396 _failures = true;
5397 return true;
5398 }
5399 }
5400 }
5401 return false;
5402 }
5403
5404 bool failures() const { return _failures; }
5405 };
5406
5407 bool G1CollectedHeap::check_cset_fast_test() {
5408 G1CheckCSetFastTableClosure cl;
5409 _hrm.iterate(&cl);
5410 return !cl.failures();
5411 }
5412 #endif // PRODUCT
5413
5414 class G1ParScrubRemSetTask: public AbstractGangTask {
5415 protected:
5416 G1RemSet* _g1rs;
5417 BitMap* _region_bm;
5418 BitMap* _card_bm;
5419 HeapRegionClaimer _hrclaimer;
5420
5421 public:
5422 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
5423 AbstractGangTask("G1 ScrubRS"),
5424 _g1rs(g1_rs),
5425 _region_bm(region_bm),
5426 _card_bm(card_bm),
5427 _hrclaimer(num_workers) {
5428 }
5429
5430 void work(uint worker_id) {
5431 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
5432 }
5433 };
5434
5435 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
5436 uint num_workers = workers()->active_workers();
5437 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
5438 workers()->run_task(&g1_par_scrub_rs_task);
5439 }
5440
5441 void G1CollectedHeap::cleanUpCardTable() {
5442 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5443 double start = os::elapsedTime();
5444
5445 {
5446 // Iterate over the dirty cards region list.
5447 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5448
5449 workers()->run_task(&cleanup_task);
5450 #ifndef PRODUCT
5451 if (G1VerifyCTCleanup || VerifyAfterGC) {
5452 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5453 heap_region_iterate(&cleanup_verifier);
5454 }
5455 #endif
5456 }
5457
5458 double elapsed = os::elapsedTime() - start;
5459 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5460 }
5461
5462 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5463 size_t pre_used = 0;
5464 FreeRegionList local_free_list("Local List for CSet Freeing");
5465
5466 double young_time_ms = 0.0;
5467 double non_young_time_ms = 0.0;
5468
5469 // Since the collection set is a superset of the the young list,
5470 // all we need to do to clear the young list is clear its
5471 // head and length, and unlink any young regions in the code below
5472 _young_list->clear();
5473
5474 G1CollectorPolicy* policy = g1_policy();
5475
5476 double start_sec = os::elapsedTime();
5477 bool non_young = true;
5478
5479 HeapRegion* cur = cs_head;
5480 int age_bound = -1;
5481 size_t rs_lengths = 0;
5482
5483 while (cur != NULL) {
5484 assert(!is_on_master_free_list(cur), "sanity");
5485 if (non_young) {
5486 if (cur->is_young()) {
5487 double end_sec = os::elapsedTime();
5488 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5489 non_young_time_ms += elapsed_ms;
5490
5491 start_sec = os::elapsedTime();
5492 non_young = false;
5493 }
5494 } else {
5495 if (!cur->is_young()) {
5496 double end_sec = os::elapsedTime();
5497 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5498 young_time_ms += elapsed_ms;
5499
5500 start_sec = os::elapsedTime();
5501 non_young = true;
5502 }
5503 }
5504
5505 rs_lengths += cur->rem_set()->occupied_locked();
5506
5507 HeapRegion* next = cur->next_in_collection_set();
5508 assert(cur->in_collection_set(), "bad CS");
5509 cur->set_next_in_collection_set(NULL);
5510 clear_in_cset(cur);
5511
5512 if (cur->is_young()) {
5513 int index = cur->young_index_in_cset();
5514 assert(index != -1, "invariant");
5515 assert((uint) index < policy->young_cset_region_length(), "invariant");
5516 size_t words_survived = surviving_young_words[index];
5517 cur->record_surv_words_in_group(words_survived);
5518
5519 // At this point the we have 'popped' cur from the collection set
5520 // (linked via next_in_collection_set()) but it is still in the
5521 // young list (linked via next_young_region()). Clear the
5522 // _next_young_region field.
5523 cur->set_next_young_region(NULL);
5524 } else {
5525 int index = cur->young_index_in_cset();
5526 assert(index == -1, "invariant");
5527 }
5528
5529 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5530 (!cur->is_young() && cur->young_index_in_cset() == -1),
5531 "invariant" );
5532
5533 if (!cur->evacuation_failed()) {
5534 MemRegion used_mr = cur->used_region();
5535
5536 // And the region is empty.
5537 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5538 pre_used += cur->used();
5539 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5540 } else {
5541 cur->uninstall_surv_rate_group();
5542 if (cur->is_young()) {
5543 cur->set_young_index_in_cset(-1);
5544 }
5545 cur->set_evacuation_failed(false);
5546 // When moving a young gen region to old gen, we "allocate" that whole region
5547 // there. This is in addition to any already evacuated objects. Notify the
5548 // policy about that.
5549 // Old gen regions do not cause an additional allocation: both the objects
5550 // still in the region and the ones already moved are accounted for elsewhere.
5551 if (cur->is_young()) {
5552 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
5553 }
5554 // The region is now considered to be old.
5555 cur->set_old();
5556 // Do some allocation statistics accounting. Regions that failed evacuation
5557 // are always made old, so there is no need to update anything in the young
5558 // gen statistics, but we need to update old gen statistics.
5559 size_t used_words = cur->marked_bytes() / HeapWordSize;
5560 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5561 _old_set.add(cur);
5562 evacuation_info.increment_collectionset_used_after(cur->used());
5563 }
5564 cur = next;
5565 }
5566
5567 evacuation_info.set_regions_freed(local_free_list.length());
5568 policy->record_max_rs_lengths(rs_lengths);
5569 policy->cset_regions_freed();
5570
5571 double end_sec = os::elapsedTime();
5572 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5573
5574 if (non_young) {
5575 non_young_time_ms += elapsed_ms;
5576 } else {
5577 young_time_ms += elapsed_ms;
5578 }
5579
5580 prepend_to_freelist(&local_free_list);
5581 decrement_summary_bytes(pre_used);
5582 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5583 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5584 }
5585
5586 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5587 private:
5588 FreeRegionList* _free_region_list;
5589 HeapRegionSet* _proxy_set;
5590 uint _humongous_regions_removed;
5591 size_t _freed_bytes;
5592 public:
5593
5594 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5595 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
5596 }
5597
5598 virtual bool doHeapRegion(HeapRegion* r) {
5599 if (!r->is_starts_humongous()) {
5600 return false;
5601 }
5602
5603 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5604
5605 oop obj = (oop)r->bottom();
5606 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5607
5608 // The following checks whether the humongous object is live are sufficient.
5609 // The main additional check (in addition to having a reference from the roots
5610 // or the young gen) is whether the humongous object has a remembered set entry.
5611 //
5612 // A humongous object cannot be live if there is no remembered set for it
5613 // because:
5614 // - there can be no references from within humongous starts regions referencing
5615 // the object because we never allocate other objects into them.
5616 // (I.e. there are no intra-region references that may be missed by the
5617 // remembered set)
5618 // - as soon there is a remembered set entry to the humongous starts region
5619 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5620 // until the end of a concurrent mark.
5621 //
5622 // It is not required to check whether the object has been found dead by marking
5623 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5624 // all objects allocated during that time are considered live.
5625 // SATB marking is even more conservative than the remembered set.
5626 // So if at this point in the collection there is no remembered set entry,
5627 // nobody has a reference to it.
5628 // At the start of collection we flush all refinement logs, and remembered sets
5629 // are completely up-to-date wrt to references to the humongous object.
5630 //
5631 // Other implementation considerations:
5632 // - never consider object arrays at this time because they would pose
5633 // considerable effort for cleaning up the the remembered sets. This is
5634 // required because stale remembered sets might reference locations that
5635 // are currently allocated into.
5636 uint region_idx = r->hrm_index();
5637 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5638 !r->rem_set()->is_empty()) {
5639 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",
5640 region_idx,
5641 (size_t)obj->size() * HeapWordSize,
5642 p2i(r->bottom()),
5643 r->rem_set()->occupied(),
5644 r->rem_set()->strong_code_roots_list_length(),
5645 next_bitmap->isMarked(r->bottom()),
5646 g1h->is_humongous_reclaim_candidate(region_idx),
5647 obj->is_typeArray()
5648 );
5649 return false;
5650 }
5651
5652 guarantee(obj->is_typeArray(),
5653 "Only eagerly reclaiming type arrays is supported, but the object "
5654 PTR_FORMAT " is not.", p2i(r->bottom()));
5655
5656 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",
5657 region_idx,
5658 (size_t)obj->size() * HeapWordSize,
5659 p2i(r->bottom()),
5660 r->rem_set()->occupied(),
5661 r->rem_set()->strong_code_roots_list_length(),
5662 next_bitmap->isMarked(r->bottom()),
5663 g1h->is_humongous_reclaim_candidate(region_idx),
5664 obj->is_typeArray()
5665 );
5666
5667 // Need to clear mark bit of the humongous object if already set.
5668 if (next_bitmap->isMarked(r->bottom())) {
5669 next_bitmap->clear(r->bottom());
5670 }
5671 do {
5672 HeapRegion* next = g1h->next_region_in_humongous(r);
5673 _freed_bytes += r->used();
5674 r->set_containing_set(NULL);
5675 _humongous_regions_removed++;
5676 g1h->free_humongous_region(r, _free_region_list, false);
5677 r = next;
5678 } while (r != NULL);
5679
5680 return false;
5681 }
5682
5683 uint humongous_free_count() {
5684 return _humongous_regions_removed;
5685 }
5686
5687 size_t bytes_freed() const {
5688 return _freed_bytes;
5689 }
5690 };
5691
5692 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5693 assert_at_safepoint(true);
5694
5695 if (!G1EagerReclaimHumongousObjects ||
5696 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5697 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5698 return;
5699 }
5700
5701 double start_time = os::elapsedTime();
5702
5703 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5704
5705 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5706 heap_region_iterate(&cl);
5707
5708 remove_from_old_sets(0, cl.humongous_free_count());
5709
5710 G1HRPrinter* hrp = hr_printer();
5711 if (hrp->is_active()) {
5712 FreeRegionListIterator iter(&local_cleanup_list);
5713 while (iter.more_available()) {
5714 HeapRegion* hr = iter.get_next();
5715 hrp->cleanup(hr);
5716 }
5717 }
5718
5719 prepend_to_freelist(&local_cleanup_list);
5720 decrement_summary_bytes(cl.bytes_freed());
5721
5722 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5723 cl.humongous_free_count());
5724 }
5725
5726 // This routine is similar to the above but does not record
5727 // any policy statistics or update free lists; we are abandoning
5728 // the current incremental collection set in preparation of a
5729 // full collection. After the full GC we will start to build up
5730 // the incremental collection set again.
5731 // This is only called when we're doing a full collection
5732 // and is immediately followed by the tearing down of the young list.
5733
5734 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5735 HeapRegion* cur = cs_head;
5736
5737 while (cur != NULL) {
5738 HeapRegion* next = cur->next_in_collection_set();
5739 assert(cur->in_collection_set(), "bad CS");
5740 cur->set_next_in_collection_set(NULL);
5741 clear_in_cset(cur);
5742 cur->set_young_index_in_cset(-1);
5743 cur = next;
5744 }
5745 }
5746
5747 void G1CollectedHeap::set_free_regions_coming() {
5748 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5749
5750 assert(!free_regions_coming(), "pre-condition");
5751 _free_regions_coming = true;
5752 }
5753
5754 void G1CollectedHeap::reset_free_regions_coming() {
5755 assert(free_regions_coming(), "pre-condition");
5756
5757 {
5758 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5759 _free_regions_coming = false;
5760 SecondaryFreeList_lock->notify_all();
5761 }
5762
5763 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5764 }
5765
5766 void G1CollectedHeap::wait_while_free_regions_coming() {
5767 // Most of the time we won't have to wait, so let's do a quick test
5768 // first before we take the lock.
5769 if (!free_regions_coming()) {
5770 return;
5771 }
5772
5773 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5774
5775 {
5776 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5777 while (free_regions_coming()) {
5778 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5779 }
5780 }
5781
5782 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5783 }
5784
5785 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5786 return _allocator->is_retained_old_region(hr);
5787 }
5788
5789 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5790 _young_list->push_region(hr);
5791 }
5792
5793 class NoYoungRegionsClosure: public HeapRegionClosure {
5794 private:
5795 bool _success;
5796 public:
5797 NoYoungRegionsClosure() : _success(true) { }
5798 bool doHeapRegion(HeapRegion* r) {
5799 if (r->is_young()) {
5800 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5801 p2i(r->bottom()), p2i(r->end()));
5802 _success = false;
5803 }
5804 return false;
5805 }
5806 bool success() { return _success; }
5807 };
5808
5809 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5810 bool ret = _young_list->check_list_empty(check_sample);
5811
5812 if (check_heap) {
5813 NoYoungRegionsClosure closure;
5814 heap_region_iterate(&closure);
5815 ret = ret && closure.success();
5816 }
5817
5818 return ret;
5819 }
5820
5821 class TearDownRegionSetsClosure : public HeapRegionClosure {
5822 private:
5823 HeapRegionSet *_old_set;
5824
5825 public:
5826 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5827
5828 bool doHeapRegion(HeapRegion* r) {
5829 if (r->is_old()) {
5830 _old_set->remove(r);
5831 } else {
5832 // We ignore free regions, we'll empty the free list afterwards.
5833 // We ignore young regions, we'll empty the young list afterwards.
5834 // We ignore humongous regions, we're not tearing down the
5835 // humongous regions set.
5836 assert(r->is_free() || r->is_young() || r->is_humongous(),
5837 "it cannot be another type");
5838 }
5839 return false;
5840 }
5841
5842 ~TearDownRegionSetsClosure() {
5843 assert(_old_set->is_empty(), "post-condition");
5844 }
5845 };
5846
5847 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5848 assert_at_safepoint(true /* should_be_vm_thread */);
5849
5850 if (!free_list_only) {
5851 TearDownRegionSetsClosure cl(&_old_set);
5852 heap_region_iterate(&cl);
5853
5854 // Note that emptying the _young_list is postponed and instead done as
5855 // the first step when rebuilding the regions sets again. The reason for
5856 // this is that during a full GC string deduplication needs to know if
5857 // a collected region was young or old when the full GC was initiated.
5858 }
5859 _hrm.remove_all_free_regions();
5860 }
5861
5862 void G1CollectedHeap::increase_used(size_t bytes) {
5863 _summary_bytes_used += bytes;
5864 }
5865
5866 void G1CollectedHeap::decrease_used(size_t bytes) {
5867 assert(_summary_bytes_used >= bytes,
5868 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5869 _summary_bytes_used, bytes);
5870 _summary_bytes_used -= bytes;
5871 }
5872
5873 void G1CollectedHeap::set_used(size_t bytes) {
5874 _summary_bytes_used = bytes;
5875 }
5876
5877 class RebuildRegionSetsClosure : public HeapRegionClosure {
5878 private:
5879 bool _free_list_only;
5880 HeapRegionSet* _old_set;
5881 HeapRegionManager* _hrm;
5882 size_t _total_used;
5883
5884 public:
5885 RebuildRegionSetsClosure(bool free_list_only,
5886 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5887 _free_list_only(free_list_only),
5888 _old_set(old_set), _hrm(hrm), _total_used(0) {
5889 assert(_hrm->num_free_regions() == 0, "pre-condition");
5890 if (!free_list_only) {
5891 assert(_old_set->is_empty(), "pre-condition");
5892 }
5893 }
5894
5895 bool doHeapRegion(HeapRegion* r) {
5896 if (r->is_empty()) {
5897 // Add free regions to the free list
5898 r->set_free();
5899 r->set_allocation_context(AllocationContext::system());
5900 _hrm->insert_into_free_list(r);
5901 } else if (!_free_list_only) {
5902 assert(!r->is_young(), "we should not come across young regions");
5903
5904 if (r->is_humongous()) {
5905 // We ignore humongous regions. We left the humongous set unchanged.
5906 } else {
5907 // Objects that were compacted would have ended up on regions
5908 // that were previously old or free. Archive regions (which are
5909 // old) will not have been touched.
5910 assert(r->is_free() || r->is_old(), "invariant");
5911 // We now consider them old, so register as such. Leave
5912 // archive regions set that way, however, while still adding
5913 // them to the old set.
5914 if (!r->is_archive()) {
5915 r->set_old();
5916 }
5917 _old_set->add(r);
5918 }
5919 _total_used += r->used();
5920 }
5921
5922 return false;
5923 }
5924
5925 size_t total_used() {
5926 return _total_used;
5927 }
5928 };
5929
5930 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5931 assert_at_safepoint(true /* should_be_vm_thread */);
5932
5933 if (!free_list_only) {
5934 _young_list->empty_list();
5935 }
5936
5937 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5938 heap_region_iterate(&cl);
5939
5940 if (!free_list_only) {
5941 set_used(cl.total_used());
5942 if (_archive_allocator != NULL) {
5943 _archive_allocator->clear_used();
5944 }
5945 }
5946 assert(used_unlocked() == recalculate_used(),
5947 "inconsistent used_unlocked(), "
5948 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5949 used_unlocked(), recalculate_used());
5950 }
5951
5952 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5953 _refine_cte_cl->set_concurrent(concurrent);
5954 }
5955
5956 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5957 HeapRegion* hr = heap_region_containing(p);
5958 return hr->is_in(p);
5959 }
5960
5961 // Methods for the mutator alloc region
5962
5963 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5964 bool force) {
5965 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5966 assert(!force || g1_policy()->can_expand_young_list(),
5967 "if force is true we should be able to expand the young list");
5968 bool young_list_full = g1_policy()->is_young_list_full();
5969 if (force || !young_list_full) {
5970 HeapRegion* new_alloc_region = new_region(word_size,
5971 false /* is_old */,
5972 false /* do_expand */);
5973 if (new_alloc_region != NULL) {
5974 set_region_short_lived_locked(new_alloc_region);
5975 _hr_printer.alloc(new_alloc_region, young_list_full);
5976 check_bitmaps("Mutator Region Allocation", new_alloc_region);
5977 return new_alloc_region;
5978 }
5979 }
5980 return NULL;
5981 }
5982
5983 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5984 size_t allocated_bytes) {
5985 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5986 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5987
5988 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5989 increase_used(allocated_bytes);
5990 _hr_printer.retire(alloc_region);
5991 // We update the eden sizes here, when the region is retired,
5992 // instead of when it's allocated, since this is the point that its
5993 // used space has been recored in _summary_bytes_used.
5994 g1mm()->update_eden_size();
5995 }
5996
5997 // Methods for the GC alloc regions
5998
5999 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6000 uint count,
6001 InCSetState dest) {
6002 assert(FreeList_lock->owned_by_self(), "pre-condition");
6003
6004 if (count < g1_policy()->max_regions(dest)) {
6005 const bool is_survivor = (dest.is_young());
6006 HeapRegion* new_alloc_region = new_region(word_size,
6007 !is_survivor,
6008 true /* do_expand */);
6009 if (new_alloc_region != NULL) {
6010 // We really only need to do this for old regions given that we
6011 // should never scan survivors. But it doesn't hurt to do it
6012 // for survivors too.
6013 new_alloc_region->record_timestamp();
6014 if (is_survivor) {
6015 new_alloc_region->set_survivor();
6016 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6017 } else {
6018 new_alloc_region->set_old();
6019 check_bitmaps("Old Region Allocation", new_alloc_region);
6020 }
6021 _hr_printer.alloc(new_alloc_region);
6022 bool during_im = collector_state()->during_initial_mark_pause();
6023 new_alloc_region->note_start_of_copying(during_im);
6024 return new_alloc_region;
6025 }
6026 }
6027 return NULL;
6028 }
6029
6030 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6031 size_t allocated_bytes,
6032 InCSetState dest) {
6033 bool during_im = collector_state()->during_initial_mark_pause();
6034 alloc_region->note_end_of_copying(during_im);
6035 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6036 if (dest.is_young()) {
6037 young_list()->add_survivor_region(alloc_region);
6038 } else {
6039 _old_set.add(alloc_region);
6040 }
6041 _hr_printer.retire(alloc_region);
6042 }
6043
6044 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6045 bool expanded = false;
6046 uint index = _hrm.find_highest_free(&expanded);
6047
6048 if (index != G1_NO_HRM_INDEX) {
6049 if (expanded) {
6050 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
6051 HeapRegion::GrainWords * HeapWordSize);
6052 }
6053 _hrm.allocate_free_regions_starting_at(index, 1);
6054 return region_at(index);
6055 }
6056 return NULL;
6057 }
6058
6059 // Heap region set verification
6060
6061 class VerifyRegionListsClosure : public HeapRegionClosure {
6062 private:
6063 HeapRegionSet* _old_set;
6064 HeapRegionSet* _humongous_set;
6065 HeapRegionManager* _hrm;
6066
6067 public:
6068 uint _old_count;
6069 uint _humongous_count;
6070 uint _free_count;
6071
6072 VerifyRegionListsClosure(HeapRegionSet* old_set,
6073 HeapRegionSet* humongous_set,
6074 HeapRegionManager* hrm) :
6075 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6076 _old_count(), _humongous_count(), _free_count(){ }
6077
6078 bool doHeapRegion(HeapRegion* hr) {
6079 if (hr->is_young()) {
6080 // TODO
6081 } else if (hr->is_humongous()) {
6082 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6083 _humongous_count++;
6084 } else if (hr->is_empty()) {
6085 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6086 _free_count++;
6087 } else if (hr->is_old()) {
6088 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6089 _old_count++;
6090 } else {
6091 // There are no other valid region types. Check for one invalid
6092 // one we can identify: pinned without old or humongous set.
6093 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6094 ShouldNotReachHere();
6095 }
6096 return false;
6097 }
6098
6099 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6100 guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);
6101 guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);
6102 guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);
6103 }
6104 };
6105
6106 void G1CollectedHeap::verify_region_sets() {
6107 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6108
6109 // First, check the explicit lists.
6110 _hrm.verify();
6111 {
6112 // Given that a concurrent operation might be adding regions to
6113 // the secondary free list we have to take the lock before
6114 // verifying it.
6115 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6116 _secondary_free_list.verify_list();
6117 }
6118
6119 // If a concurrent region freeing operation is in progress it will
6120 // be difficult to correctly attributed any free regions we come
6121 // across to the correct free list given that they might belong to
6122 // one of several (free_list, secondary_free_list, any local lists,
6123 // etc.). So, if that's the case we will skip the rest of the
6124 // verification operation. Alternatively, waiting for the concurrent
6125 // operation to complete will have a non-trivial effect on the GC's
6126 // operation (no concurrent operation will last longer than the
6127 // interval between two calls to verification) and it might hide
6128 // any issues that we would like to catch during testing.
6129 if (free_regions_coming()) {
6130 return;
6131 }
6132
6133 // Make sure we append the secondary_free_list on the free_list so
6134 // that all free regions we will come across can be safely
6135 // attributed to the free_list.
6136 append_secondary_free_list_if_not_empty_with_lock();
6137
6138 // Finally, make sure that the region accounting in the lists is
6139 // consistent with what we see in the heap.
6140
6141 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6142 heap_region_iterate(&cl);
6143 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6144 }
6145
6146 // Optimized nmethod scanning
6147
6148 class RegisterNMethodOopClosure: public OopClosure {
6149 G1CollectedHeap* _g1h;
6150 nmethod* _nm;
6151
6152 template <class T> void do_oop_work(T* p) {
6153 T heap_oop = oopDesc::load_heap_oop(p);
6154 if (!oopDesc::is_null(heap_oop)) {
6155 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6156 HeapRegion* hr = _g1h->heap_region_containing(obj);
6157 assert(!hr->is_continues_humongous(),
6158 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6159 " starting at " HR_FORMAT,
6160 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6161
6162 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6163 hr->add_strong_code_root_locked(_nm);
6164 }
6165 }
6166
6167 public:
6168 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6169 _g1h(g1h), _nm(nm) {}
6170
6171 void do_oop(oop* p) { do_oop_work(p); }
6172 void do_oop(narrowOop* p) { do_oop_work(p); }
6173 };
6174
6175 class UnregisterNMethodOopClosure: public OopClosure {
6176 G1CollectedHeap* _g1h;
6177 nmethod* _nm;
6178
6179 template <class T> void do_oop_work(T* p) {
6180 T heap_oop = oopDesc::load_heap_oop(p);
6181 if (!oopDesc::is_null(heap_oop)) {
6182 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6183 HeapRegion* hr = _g1h->heap_region_containing(obj);
6184 assert(!hr->is_continues_humongous(),
6185 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6186 " starting at " HR_FORMAT,
6187 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6188
6189 hr->remove_strong_code_root(_nm);
6190 }
6191 }
6192
6193 public:
6194 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6195 _g1h(g1h), _nm(nm) {}
6196
6197 void do_oop(oop* p) { do_oop_work(p); }
6198 void do_oop(narrowOop* p) { do_oop_work(p); }
6199 };
6200
6201 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6202 CollectedHeap::register_nmethod(nm);
6203
6204 guarantee(nm != NULL, "sanity");
6205 RegisterNMethodOopClosure reg_cl(this, nm);
6206 nm->oops_do(®_cl);
6207 }
6208
6209 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6210 CollectedHeap::unregister_nmethod(nm);
6211
6212 guarantee(nm != NULL, "sanity");
6213 UnregisterNMethodOopClosure reg_cl(this, nm);
6214 nm->oops_do(®_cl, true);
6215 }
6216
6217 void G1CollectedHeap::purge_code_root_memory() {
6218 double purge_start = os::elapsedTime();
6219 G1CodeRootSet::purge();
6220 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6221 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6222 }
6223
6224 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6225 G1CollectedHeap* _g1h;
6226
6227 public:
6228 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6229 _g1h(g1h) {}
6230
6231 void do_code_blob(CodeBlob* cb) {
6232 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6233 if (nm == NULL) {
6234 return;
6235 }
6236
6237 if (ScavengeRootsInCode) {
6238 _g1h->register_nmethod(nm);
6239 }
6240 }
6241 };
6242
6243 void G1CollectedHeap::rebuild_strong_code_roots() {
6244 RebuildStrongCodeRootClosure blob_cl(this);
6245 CodeCache::blobs_do(&blob_cl);
6246 }