1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1MarkSweep.hpp"
46 #include "gc/g1/g1OopClosures.inline.hpp"
47 #include "gc/g1/g1ParScanThreadState.inline.hpp"
48 #include "gc/g1/g1RegionToSpaceMapper.hpp"
49 #include "gc/g1/g1RemSet.inline.hpp"
50 #include "gc/g1/g1RootClosures.hpp"
51 #include "gc/g1/g1RootProcessor.hpp"
52 #include "gc/g1/g1StringDedup.hpp"
53 #include "gc/g1/g1YCTypes.hpp"
54 #include "gc/g1/heapRegion.inline.hpp"
55 #include "gc/g1/heapRegionRemSet.hpp"
56 #include "gc/g1/heapRegionSet.inline.hpp"
57 #include "gc/g1/suspendibleThreadSet.hpp"
58 #include "gc/g1/vm_operations_g1.hpp"
59 #include "gc/shared/gcHeapSummary.hpp"
60 #include "gc/shared/gcId.hpp"
61 #include "gc/shared/gcLocker.inline.hpp"
62 #include "gc/shared/gcTimer.hpp"
63 #include "gc/shared/gcTrace.hpp"
64 #include "gc/shared/gcTraceTime.inline.hpp"
65 #include "gc/shared/generationSpec.hpp"
66 #include "gc/shared/isGCActiveMark.hpp"
67 #include "gc/shared/referenceProcessor.inline.hpp"
68 #include "gc/shared/taskqueue.inline.hpp"
69 #include "logging/log.hpp"
70 #include "memory/allocation.hpp"
71 #include "memory/iterator.hpp"
72 #include "memory/resourceArea.hpp"
73 #include "oops/oop.inline.hpp"
74 #include "runtime/atomic.inline.hpp"
75 #include "runtime/init.hpp"
76 #include "runtime/orderAccess.inline.hpp"
77 #include "runtime/vmThread.hpp"
78 #include "utilities/globalDefinitions.hpp"
79 #include "utilities/stack.inline.hpp"
80
81 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_dirtied;
121 G1CollectedHeap* _g1h;
122 G1SATBCardTableLoggingModRefBS* _g1_bs;
123
124 HeapRegion* region_for_card(jbyte* card_ptr) const {
125 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
126 }
127
128 bool will_become_free(HeapRegion* hr) const {
129 // A region will be freed by free_collection_set if the region is in the
130 // collection set and has not had an evacuation failure.
131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
132 }
133
134 public:
135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
136 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
137
138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
139 HeapRegion* hr = region_for_card(card_ptr);
140
141 // Should only dirty cards in regions that won't be freed.
142 if (!will_become_free(hr)) {
143 *card_ptr = CardTableModRefBS::dirty_card_val();
144 _num_dirtied++;
145 }
146
147 return true;
148 }
149
150 size_t num_dirtied() const { return _num_dirtied; }
151 };
152
153
154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
156 }
157
158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
159 // The from card cache is not the memory that is actually committed. So we cannot
160 // take advantage of the zero_filled parameter.
161 reset_from_card_cache(start_idx, num_regions);
162 }
163
164 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
165 {
166 // Claim the right to put the region on the dirty cards region list
167 // by installing a self pointer.
168 HeapRegion* next = hr->get_next_dirty_cards_region();
169 if (next == NULL) {
170 HeapRegion* res = (HeapRegion*)
171 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
172 NULL);
173 if (res == NULL) {
174 HeapRegion* head;
175 do {
176 // Put the region to the dirty cards region list.
177 head = _dirty_cards_region_list;
178 next = (HeapRegion*)
179 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
180 if (next == head) {
181 assert(hr->get_next_dirty_cards_region() == hr,
182 "hr->get_next_dirty_cards_region() != hr");
183 if (next == NULL) {
184 // The last region in the list points to itself.
185 hr->set_next_dirty_cards_region(hr);
186 } else {
187 hr->set_next_dirty_cards_region(next);
188 }
189 }
190 } while (next != head);
191 }
192 }
193 }
194
195 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
196 {
197 HeapRegion* head;
198 HeapRegion* hr;
199 do {
200 head = _dirty_cards_region_list;
201 if (head == NULL) {
202 return NULL;
203 }
204 HeapRegion* new_head = head->get_next_dirty_cards_region();
205 if (head == new_head) {
206 // The last region.
207 new_head = NULL;
208 }
209 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
210 head);
211 } while (hr != head);
212 assert(hr != NULL, "invariant");
213 hr->set_next_dirty_cards_region(NULL);
214 return hr;
215 }
216
217 // Returns true if the reference points to an object that
218 // can move in an incremental collection.
219 bool G1CollectedHeap::is_scavengable(const void* p) {
220 HeapRegion* hr = heap_region_containing(p);
221 return !hr->is_pinned();
222 }
223
224 // Private methods.
225
226 HeapRegion*
227 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
228 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
229 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
230 if (!_secondary_free_list.is_empty()) {
231 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
232 "secondary_free_list has %u entries",
233 _secondary_free_list.length());
234 // It looks as if there are free regions available on the
235 // secondary_free_list. Let's move them to the free_list and try
236 // again to allocate from it.
237 append_secondary_free_list();
238
239 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
240 "empty we should have moved at least one entry to the free_list");
241 HeapRegion* res = _hrm.allocate_free_region(is_old);
242 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
243 "allocated " HR_FORMAT " from secondary_free_list",
244 HR_FORMAT_PARAMS(res));
245 return res;
246 }
247
248 // Wait here until we get notified either when (a) there are no
249 // more free regions coming or (b) some regions have been moved on
250 // the secondary_free_list.
251 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
252 }
253
254 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
255 "could not allocate from secondary_free_list");
256 return NULL;
257 }
258
259 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
260 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
261 "the only time we use this to allocate a humongous region is "
262 "when we are allocating a single humongous region");
263
264 HeapRegion* res;
265 if (G1StressConcRegionFreeing) {
266 if (!_secondary_free_list.is_empty()) {
267 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
268 "forced to look at the secondary_free_list");
269 res = new_region_try_secondary_free_list(is_old);
270 if (res != NULL) {
271 return res;
272 }
273 }
274 }
275
276 res = _hrm.allocate_free_region(is_old);
277
278 if (res == NULL) {
279 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
280 "res == NULL, trying the secondary_free_list");
281 res = new_region_try_secondary_free_list(is_old);
282 }
283 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
284 // Currently, only attempts to allocate GC alloc regions set
285 // do_expand to true. So, we should only reach here during a
286 // safepoint. If this assumption changes we might have to
287 // reconsider the use of _expand_heap_after_alloc_failure.
288 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
289
290 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
291 word_size * HeapWordSize);
292
293 if (expand(word_size * HeapWordSize)) {
294 // Given that expand() succeeded in expanding the heap, and we
295 // always expand the heap by an amount aligned to the heap
296 // region size, the free list should in theory not be empty.
297 // In either case allocate_free_region() will check for NULL.
298 res = _hrm.allocate_free_region(is_old);
299 } else {
300 _expand_heap_after_alloc_failure = false;
301 }
302 }
303 return res;
304 }
305
306 HeapWord*
307 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
308 uint num_regions,
309 size_t word_size,
310 AllocationContext_t context) {
311 assert(first != G1_NO_HRM_INDEX, "pre-condition");
312 assert(is_humongous(word_size), "word_size should be humongous");
313 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
314
315 // Index of last region in the series.
316 uint last = first + num_regions - 1;
317
318 // We need to initialize the region(s) we just discovered. This is
319 // a bit tricky given that it can happen concurrently with
320 // refinement threads refining cards on these regions and
321 // potentially wanting to refine the BOT as they are scanning
322 // those cards (this can happen shortly after a cleanup; see CR
323 // 6991377). So we have to set up the region(s) carefully and in
324 // a specific order.
325
326 // The word size sum of all the regions we will allocate.
327 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
328 assert(word_size <= word_size_sum, "sanity");
329
330 // This will be the "starts humongous" region.
331 HeapRegion* first_hr = region_at(first);
332 // The header of the new object will be placed at the bottom of
333 // the first region.
334 HeapWord* new_obj = first_hr->bottom();
335 // This will be the new top of the new object.
336 HeapWord* obj_top = new_obj + word_size;
337
338 // First, we need to zero the header of the space that we will be
339 // allocating. When we update top further down, some refinement
340 // threads might try to scan the region. By zeroing the header we
341 // ensure that any thread that will try to scan the region will
342 // come across the zero klass word and bail out.
343 //
344 // NOTE: It would not have been correct to have used
345 // CollectedHeap::fill_with_object() and make the space look like
346 // an int array. The thread that is doing the allocation will
347 // later update the object header to a potentially different array
348 // type and, for a very short period of time, the klass and length
349 // fields will be inconsistent. This could cause a refinement
350 // thread to calculate the object size incorrectly.
351 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
352
353 // How many words we use for filler objects.
354 size_t word_fill_size = word_size_sum - word_size;
355
356 // How many words memory we "waste" which cannot hold a filler object.
357 size_t words_not_fillable = 0;
358
359 if (word_fill_size >= min_fill_size()) {
360 fill_with_objects(obj_top, word_fill_size);
361 } else if (word_fill_size > 0) {
362 // We have space to fill, but we cannot fit an object there.
363 words_not_fillable = word_fill_size;
364 word_fill_size = 0;
365 }
366
367 // We will set up the first region as "starts humongous". This
368 // will also update the BOT covering all the regions to reflect
369 // that there is a single object that starts at the bottom of the
370 // first region.
371 first_hr->set_starts_humongous(obj_top, word_fill_size);
372 first_hr->set_allocation_context(context);
373 // Then, if there are any, we will set up the "continues
374 // humongous" regions.
375 HeapRegion* hr = NULL;
376 for (uint i = first + 1; i <= last; ++i) {
377 hr = region_at(i);
378 hr->set_continues_humongous(first_hr);
379 hr->set_allocation_context(context);
380 }
381
382 // Up to this point no concurrent thread would have been able to
383 // do any scanning on any region in this series. All the top
384 // fields still point to bottom, so the intersection between
385 // [bottom,top] and [card_start,card_end] will be empty. Before we
386 // update the top fields, we'll do a storestore to make sure that
387 // no thread sees the update to top before the zeroing of the
388 // object header and the BOT initialization.
389 OrderAccess::storestore();
390
391 // Now, we will update the top fields of the "continues humongous"
392 // regions except the last one.
393 for (uint i = first; i < last; ++i) {
394 hr = region_at(i);
395 hr->set_top(hr->end());
396 }
397
398 hr = region_at(last);
399 // If we cannot fit a filler object, we must set top to the end
400 // of the humongous object, otherwise we cannot iterate the heap
401 // and the BOT will not be complete.
402 hr->set_top(hr->end() - words_not_fillable);
403
404 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
405 "obj_top should be in last region");
406
407 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
408
409 assert(words_not_fillable == 0 ||
410 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
411 "Miscalculation in humongous allocation");
412
413 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
414
415 for (uint i = first; i <= last; ++i) {
416 hr = region_at(i);
417 _humongous_set.add(hr);
418 _hr_printer.alloc(hr);
419 }
420
421 return new_obj;
422 }
423
424 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
425 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
426 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
427 }
428
429 // If could fit into free regions w/o expansion, try.
430 // Otherwise, if can expand, do so.
431 // Otherwise, if using ex regions might help, try with ex given back.
432 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
433 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
434
435 _verifier->verify_region_sets_optional();
436
437 uint first = G1_NO_HRM_INDEX;
438 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
439
440 if (obj_regions == 1) {
441 // Only one region to allocate, try to use a fast path by directly allocating
442 // from the free lists. Do not try to expand here, we will potentially do that
443 // later.
444 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
445 if (hr != NULL) {
446 first = hr->hrm_index();
447 }
448 } else {
449 // We can't allocate humongous regions spanning more than one region while
450 // cleanupComplete() is running, since some of the regions we find to be
451 // empty might not yet be added to the free list. It is not straightforward
452 // to know in which list they are on so that we can remove them. We only
453 // need to do this if we need to allocate more than one region to satisfy the
454 // current humongous allocation request. If we are only allocating one region
455 // we use the one-region region allocation code (see above), that already
456 // potentially waits for regions from the secondary free list.
457 wait_while_free_regions_coming();
458 append_secondary_free_list_if_not_empty_with_lock();
459
460 // Policy: Try only empty regions (i.e. already committed first). Maybe we
461 // are lucky enough to find some.
462 first = _hrm.find_contiguous_only_empty(obj_regions);
463 if (first != G1_NO_HRM_INDEX) {
464 _hrm.allocate_free_regions_starting_at(first, obj_regions);
465 }
466 }
467
468 if (first == G1_NO_HRM_INDEX) {
469 // Policy: We could not find enough regions for the humongous object in the
470 // free list. Look through the heap to find a mix of free and uncommitted regions.
471 // If so, try expansion.
472 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
473 if (first != G1_NO_HRM_INDEX) {
474 // We found something. Make sure these regions are committed, i.e. expand
475 // the heap. Alternatively we could do a defragmentation GC.
476 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
477 word_size * HeapWordSize);
478
479
480 _hrm.expand_at(first, obj_regions);
481 g1_policy()->record_new_heap_size(num_regions());
482
483 #ifdef ASSERT
484 for (uint i = first; i < first + obj_regions; ++i) {
485 HeapRegion* hr = region_at(i);
486 assert(hr->is_free(), "sanity");
487 assert(hr->is_empty(), "sanity");
488 assert(is_on_master_free_list(hr), "sanity");
489 }
490 #endif
491 _hrm.allocate_free_regions_starting_at(first, obj_regions);
492 } else {
493 // Policy: Potentially trigger a defragmentation GC.
494 }
495 }
496
497 HeapWord* result = NULL;
498 if (first != G1_NO_HRM_INDEX) {
499 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
500 word_size, context);
501 assert(result != NULL, "it should always return a valid result");
502
503 // A successful humongous object allocation changes the used space
504 // information of the old generation so we need to recalculate the
505 // sizes and update the jstat counters here.
506 g1mm()->update_sizes();
507 }
508
509 _verifier->verify_region_sets_optional();
510
511 return result;
512 }
513
514 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
515 assert_heap_not_locked_and_not_at_safepoint();
516 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
517
518 uint dummy_gc_count_before;
519 uint dummy_gclocker_retry_count = 0;
520 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
521 }
522
523 HeapWord*
524 G1CollectedHeap::mem_allocate(size_t word_size,
525 bool* gc_overhead_limit_was_exceeded) {
526 assert_heap_not_locked_and_not_at_safepoint();
527
528 // Loop until the allocation is satisfied, or unsatisfied after GC.
529 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
530 uint gc_count_before;
531
532 HeapWord* result = NULL;
533 if (!is_humongous(word_size)) {
534 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
535 } else {
536 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
537 }
538 if (result != NULL) {
539 return result;
540 }
541
542 // Create the garbage collection operation...
543 VM_G1CollectForAllocation op(gc_count_before, word_size);
544 op.set_allocation_context(AllocationContext::current());
545
546 // ...and get the VM thread to execute it.
547 VMThread::execute(&op);
548
549 if (op.prologue_succeeded() && op.pause_succeeded()) {
550 // If the operation was successful we'll return the result even
551 // if it is NULL. If the allocation attempt failed immediately
552 // after a Full GC, it's unlikely we'll be able to allocate now.
553 HeapWord* result = op.result();
554 if (result != NULL && !is_humongous(word_size)) {
555 // Allocations that take place on VM operations do not do any
556 // card dirtying and we have to do it here. We only have to do
557 // this for non-humongous allocations, though.
558 dirty_young_block(result, word_size);
559 }
560 return result;
561 } else {
562 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
563 return NULL;
564 }
565 assert(op.result() == NULL,
566 "the result should be NULL if the VM op did not succeed");
567 }
568
569 // Give a warning if we seem to be looping forever.
570 if ((QueuedAllocationWarningCount > 0) &&
571 (try_count % QueuedAllocationWarningCount == 0)) {
572 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
573 }
574 }
575
576 ShouldNotReachHere();
577 return NULL;
578 }
579
580 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
581 AllocationContext_t context,
582 uint* gc_count_before_ret,
583 uint* gclocker_retry_count_ret) {
584 // Make sure you read the note in attempt_allocation_humongous().
585
586 assert_heap_not_locked_and_not_at_safepoint();
587 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
588 "be called for humongous allocation requests");
589
590 // We should only get here after the first-level allocation attempt
591 // (attempt_allocation()) failed to allocate.
592
593 // We will loop until a) we manage to successfully perform the
594 // allocation or b) we successfully schedule a collection which
595 // fails to perform the allocation. b) is the only case when we'll
596 // return NULL.
597 HeapWord* result = NULL;
598 for (int try_count = 1; /* we'll return */; try_count += 1) {
599 bool should_try_gc;
600 uint gc_count_before;
601
602 {
603 MutexLockerEx x(Heap_lock);
604 result = _allocator->attempt_allocation_locked(word_size, context);
605 if (result != NULL) {
606 return result;
607 }
608
609 if (GCLocker::is_active_and_needs_gc()) {
610 if (g1_policy()->can_expand_young_list()) {
611 // No need for an ergo verbose message here,
612 // can_expand_young_list() does this when it returns true.
613 result = _allocator->attempt_allocation_force(word_size, context);
614 if (result != NULL) {
615 return result;
616 }
617 }
618 should_try_gc = false;
619 } else {
620 // The GCLocker may not be active but the GCLocker initiated
621 // GC may not yet have been performed (GCLocker::needs_gc()
622 // returns true). In this case we do not try this GC and
623 // wait until the GCLocker initiated GC is performed, and
624 // then retry the allocation.
625 if (GCLocker::needs_gc()) {
626 should_try_gc = false;
627 } else {
628 // Read the GC count while still holding the Heap_lock.
629 gc_count_before = total_collections();
630 should_try_gc = true;
631 }
632 }
633 }
634
635 if (should_try_gc) {
636 bool succeeded;
637 result = do_collection_pause(word_size, gc_count_before, &succeeded,
638 GCCause::_g1_inc_collection_pause);
639 if (result != NULL) {
640 assert(succeeded, "only way to get back a non-NULL result");
641 return result;
642 }
643
644 if (succeeded) {
645 // If we get here we successfully scheduled a collection which
646 // failed to allocate. No point in trying to allocate
647 // further. We'll just return NULL.
648 MutexLockerEx x(Heap_lock);
649 *gc_count_before_ret = total_collections();
650 return NULL;
651 }
652 } else {
653 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
654 MutexLockerEx x(Heap_lock);
655 *gc_count_before_ret = total_collections();
656 return NULL;
657 }
658 // The GCLocker is either active or the GCLocker initiated
659 // GC has not yet been performed. Stall until it is and
660 // then retry the allocation.
661 GCLocker::stall_until_clear();
662 (*gclocker_retry_count_ret) += 1;
663 }
664
665 // We can reach here if we were unsuccessful in scheduling a
666 // collection (because another thread beat us to it) or if we were
667 // stalled due to the GC locker. In either can we should retry the
668 // allocation attempt in case another thread successfully
669 // performed a collection and reclaimed enough space. We do the
670 // first attempt (without holding the Heap_lock) here and the
671 // follow-on attempt will be at the start of the next loop
672 // iteration (after taking the Heap_lock).
673 result = _allocator->attempt_allocation(word_size, context);
674 if (result != NULL) {
675 return result;
676 }
677
678 // Give a warning if we seem to be looping forever.
679 if ((QueuedAllocationWarningCount > 0) &&
680 (try_count % QueuedAllocationWarningCount == 0)) {
681 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
682 "retries %d times", try_count);
683 }
684 }
685
686 ShouldNotReachHere();
687 return NULL;
688 }
689
690 void G1CollectedHeap::begin_archive_alloc_range() {
691 assert_at_safepoint(true /* should_be_vm_thread */);
692 if (_archive_allocator == NULL) {
693 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
694 }
695 }
696
697 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
698 // Allocations in archive regions cannot be of a size that would be considered
699 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
700 // may be different at archive-restore time.
701 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
702 }
703
704 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
705 assert_at_safepoint(true /* should_be_vm_thread */);
706 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
707 if (is_archive_alloc_too_large(word_size)) {
708 return NULL;
709 }
710 return _archive_allocator->archive_mem_allocate(word_size);
711 }
712
713 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
714 size_t end_alignment_in_bytes) {
715 assert_at_safepoint(true /* should_be_vm_thread */);
716 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
717
718 // Call complete_archive to do the real work, filling in the MemRegion
719 // array with the archive regions.
720 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
721 delete _archive_allocator;
722 _archive_allocator = NULL;
723 }
724
725 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
726 assert(ranges != NULL, "MemRegion array NULL");
727 assert(count != 0, "No MemRegions provided");
728 MemRegion reserved = _hrm.reserved();
729 for (size_t i = 0; i < count; i++) {
730 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
731 return false;
732 }
733 }
734 return true;
735 }
736
737 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
738 assert(!is_init_completed(), "Expect to be called at JVM init time");
739 assert(ranges != NULL, "MemRegion array NULL");
740 assert(count != 0, "No MemRegions provided");
741 MutexLockerEx x(Heap_lock);
742
743 MemRegion reserved = _hrm.reserved();
744 HeapWord* prev_last_addr = NULL;
745 HeapRegion* prev_last_region = NULL;
746
747 // Temporarily disable pretouching of heap pages. This interface is used
748 // when mmap'ing archived heap data in, so pre-touching is wasted.
749 FlagSetting fs(AlwaysPreTouch, false);
750
751 // Enable archive object checking in G1MarkSweep. We have to let it know
752 // about each archive range, so that objects in those ranges aren't marked.
753 G1MarkSweep::enable_archive_object_check();
754
755 // For each specified MemRegion range, allocate the corresponding G1
756 // regions and mark them as archive regions. We expect the ranges in
757 // ascending starting address order, without overlap.
758 for (size_t i = 0; i < count; i++) {
759 MemRegion curr_range = ranges[i];
760 HeapWord* start_address = curr_range.start();
761 size_t word_size = curr_range.word_size();
762 HeapWord* last_address = curr_range.last();
763 size_t commits = 0;
764
765 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
766 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
767 p2i(start_address), p2i(last_address));
768 guarantee(start_address > prev_last_addr,
769 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
770 p2i(start_address), p2i(prev_last_addr));
771 prev_last_addr = last_address;
772
773 // Check for ranges that start in the same G1 region in which the previous
774 // range ended, and adjust the start address so we don't try to allocate
775 // the same region again. If the current range is entirely within that
776 // region, skip it, just adjusting the recorded top.
777 HeapRegion* start_region = _hrm.addr_to_region(start_address);
778 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
779 start_address = start_region->end();
780 if (start_address > last_address) {
781 increase_used(word_size * HeapWordSize);
782 start_region->set_top(last_address + 1);
783 continue;
784 }
785 start_region->set_top(start_address);
786 curr_range = MemRegion(start_address, last_address + 1);
787 start_region = _hrm.addr_to_region(start_address);
788 }
789
790 // Perform the actual region allocation, exiting if it fails.
791 // Then note how much new space we have allocated.
792 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
793 return false;
794 }
795 increase_used(word_size * HeapWordSize);
796 if (commits != 0) {
797 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
798 HeapRegion::GrainWords * HeapWordSize * commits);
799
800 }
801
802 // Mark each G1 region touched by the range as archive, add it to the old set,
803 // and set the allocation context and top.
804 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
805 HeapRegion* last_region = _hrm.addr_to_region(last_address);
806 prev_last_region = last_region;
807
808 while (curr_region != NULL) {
809 assert(curr_region->is_empty() && !curr_region->is_pinned(),
810 "Region already in use (index %u)", curr_region->hrm_index());
811 curr_region->set_allocation_context(AllocationContext::system());
812 curr_region->set_archive();
813 _hr_printer.alloc(curr_region);
814 _old_set.add(curr_region);
815 if (curr_region != last_region) {
816 curr_region->set_top(curr_region->end());
817 curr_region = _hrm.next_region_in_heap(curr_region);
818 } else {
819 curr_region->set_top(last_address + 1);
820 curr_region = NULL;
821 }
822 }
823
824 // Notify mark-sweep of the archive range.
825 G1MarkSweep::set_range_archive(curr_range, true);
826 }
827 return true;
828 }
829
830 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
831 assert(!is_init_completed(), "Expect to be called at JVM init time");
832 assert(ranges != NULL, "MemRegion array NULL");
833 assert(count != 0, "No MemRegions provided");
834 MemRegion reserved = _hrm.reserved();
835 HeapWord *prev_last_addr = NULL;
836 HeapRegion* prev_last_region = NULL;
837
838 // For each MemRegion, create filler objects, if needed, in the G1 regions
839 // that contain the address range. The address range actually within the
840 // MemRegion will not be modified. That is assumed to have been initialized
841 // elsewhere, probably via an mmap of archived heap data.
842 MutexLockerEx x(Heap_lock);
843 for (size_t i = 0; i < count; i++) {
844 HeapWord* start_address = ranges[i].start();
845 HeapWord* last_address = ranges[i].last();
846
847 assert(reserved.contains(start_address) && reserved.contains(last_address),
848 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
849 p2i(start_address), p2i(last_address));
850 assert(start_address > prev_last_addr,
851 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
852 p2i(start_address), p2i(prev_last_addr));
853
854 HeapRegion* start_region = _hrm.addr_to_region(start_address);
855 HeapRegion* last_region = _hrm.addr_to_region(last_address);
856 HeapWord* bottom_address = start_region->bottom();
857
858 // Check for a range beginning in the same region in which the
859 // previous one ended.
860 if (start_region == prev_last_region) {
861 bottom_address = prev_last_addr + 1;
862 }
863
864 // Verify that the regions were all marked as archive regions by
865 // alloc_archive_regions.
866 HeapRegion* curr_region = start_region;
867 while (curr_region != NULL) {
868 guarantee(curr_region->is_archive(),
869 "Expected archive region at index %u", curr_region->hrm_index());
870 if (curr_region != last_region) {
871 curr_region = _hrm.next_region_in_heap(curr_region);
872 } else {
873 curr_region = NULL;
874 }
875 }
876
877 prev_last_addr = last_address;
878 prev_last_region = last_region;
879
880 // Fill the memory below the allocated range with dummy object(s),
881 // if the region bottom does not match the range start, or if the previous
882 // range ended within the same G1 region, and there is a gap.
883 if (start_address != bottom_address) {
884 size_t fill_size = pointer_delta(start_address, bottom_address);
885 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
886 increase_used(fill_size * HeapWordSize);
887 }
888 }
889 }
890
891 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
892 uint* gc_count_before_ret,
893 uint* gclocker_retry_count_ret) {
894 assert_heap_not_locked_and_not_at_safepoint();
895 assert(!is_humongous(word_size), "attempt_allocation() should not "
896 "be called for humongous allocation requests");
897
898 AllocationContext_t context = AllocationContext::current();
899 HeapWord* result = _allocator->attempt_allocation(word_size, context);
900
901 if (result == NULL) {
902 result = attempt_allocation_slow(word_size,
903 context,
904 gc_count_before_ret,
905 gclocker_retry_count_ret);
906 }
907 assert_heap_not_locked();
908 if (result != NULL) {
909 dirty_young_block(result, word_size);
910 }
911 return result;
912 }
913
914 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
915 assert(!is_init_completed(), "Expect to be called at JVM init time");
916 assert(ranges != NULL, "MemRegion array NULL");
917 assert(count != 0, "No MemRegions provided");
918 MemRegion reserved = _hrm.reserved();
919 HeapWord* prev_last_addr = NULL;
920 HeapRegion* prev_last_region = NULL;
921 size_t size_used = 0;
922 size_t uncommitted_regions = 0;
923
924 // For each Memregion, free the G1 regions that constitute it, and
925 // notify mark-sweep that the range is no longer to be considered 'archive.'
926 MutexLockerEx x(Heap_lock);
927 for (size_t i = 0; i < count; i++) {
928 HeapWord* start_address = ranges[i].start();
929 HeapWord* last_address = ranges[i].last();
930
931 assert(reserved.contains(start_address) && reserved.contains(last_address),
932 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
933 p2i(start_address), p2i(last_address));
934 assert(start_address > prev_last_addr,
935 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
936 p2i(start_address), p2i(prev_last_addr));
937 size_used += ranges[i].byte_size();
938 prev_last_addr = last_address;
939
940 HeapRegion* start_region = _hrm.addr_to_region(start_address);
941 HeapRegion* last_region = _hrm.addr_to_region(last_address);
942
943 // Check for ranges that start in the same G1 region in which the previous
944 // range ended, and adjust the start address so we don't try to free
945 // the same region again. If the current range is entirely within that
946 // region, skip it.
947 if (start_region == prev_last_region) {
948 start_address = start_region->end();
949 if (start_address > last_address) {
950 continue;
951 }
952 start_region = _hrm.addr_to_region(start_address);
953 }
954 prev_last_region = last_region;
955
956 // After verifying that each region was marked as an archive region by
957 // alloc_archive_regions, set it free and empty and uncommit it.
958 HeapRegion* curr_region = start_region;
959 while (curr_region != NULL) {
960 guarantee(curr_region->is_archive(),
961 "Expected archive region at index %u", curr_region->hrm_index());
962 uint curr_index = curr_region->hrm_index();
963 _old_set.remove(curr_region);
964 curr_region->set_free();
965 curr_region->set_top(curr_region->bottom());
966 if (curr_region != last_region) {
967 curr_region = _hrm.next_region_in_heap(curr_region);
968 } else {
969 curr_region = NULL;
970 }
971 _hrm.shrink_at(curr_index, 1);
972 uncommitted_regions++;
973 }
974
975 // Notify mark-sweep that this is no longer an archive range.
976 G1MarkSweep::set_range_archive(ranges[i], false);
977 }
978
979 if (uncommitted_regions != 0) {
980 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
981 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
982 }
983 decrease_used(size_used);
984 }
985
986 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
987 uint* gc_count_before_ret,
988 uint* gclocker_retry_count_ret) {
989 // The structure of this method has a lot of similarities to
990 // attempt_allocation_slow(). The reason these two were not merged
991 // into a single one is that such a method would require several "if
992 // allocation is not humongous do this, otherwise do that"
993 // conditional paths which would obscure its flow. In fact, an early
994 // version of this code did use a unified method which was harder to
995 // follow and, as a result, it had subtle bugs that were hard to
996 // track down. So keeping these two methods separate allows each to
997 // be more readable. It will be good to keep these two in sync as
998 // much as possible.
999
1000 assert_heap_not_locked_and_not_at_safepoint();
1001 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1002 "should only be called for humongous allocations");
1003
1004 // Humongous objects can exhaust the heap quickly, so we should check if we
1005 // need to start a marking cycle at each humongous object allocation. We do
1006 // the check before we do the actual allocation. The reason for doing it
1007 // before the allocation is that we avoid having to keep track of the newly
1008 // allocated memory while we do a GC.
1009 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1010 word_size)) {
1011 collect(GCCause::_g1_humongous_allocation);
1012 }
1013
1014 // We will loop until a) we manage to successfully perform the
1015 // allocation or b) we successfully schedule a collection which
1016 // fails to perform the allocation. b) is the only case when we'll
1017 // return NULL.
1018 HeapWord* result = NULL;
1019 for (int try_count = 1; /* we'll return */; try_count += 1) {
1020 bool should_try_gc;
1021 uint gc_count_before;
1022
1023 {
1024 MutexLockerEx x(Heap_lock);
1025
1026 // Given that humongous objects are not allocated in young
1027 // regions, we'll first try to do the allocation without doing a
1028 // collection hoping that there's enough space in the heap.
1029 result = humongous_obj_allocate(word_size, AllocationContext::current());
1030 if (result != NULL) {
1031 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1032 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1033 return result;
1034 }
1035
1036 if (GCLocker::is_active_and_needs_gc()) {
1037 should_try_gc = false;
1038 } else {
1039 // The GCLocker may not be active but the GCLocker initiated
1040 // GC may not yet have been performed (GCLocker::needs_gc()
1041 // returns true). In this case we do not try this GC and
1042 // wait until the GCLocker initiated GC is performed, and
1043 // then retry the allocation.
1044 if (GCLocker::needs_gc()) {
1045 should_try_gc = false;
1046 } else {
1047 // Read the GC count while still holding the Heap_lock.
1048 gc_count_before = total_collections();
1049 should_try_gc = true;
1050 }
1051 }
1052 }
1053
1054 if (should_try_gc) {
1055 // If we failed to allocate the humongous object, we should try to
1056 // do a collection pause (if we're allowed) in case it reclaims
1057 // enough space for the allocation to succeed after the pause.
1058
1059 bool succeeded;
1060 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1061 GCCause::_g1_humongous_allocation);
1062 if (result != NULL) {
1063 assert(succeeded, "only way to get back a non-NULL result");
1064 return result;
1065 }
1066
1067 if (succeeded) {
1068 // If we get here we successfully scheduled a collection which
1069 // failed to allocate. No point in trying to allocate
1070 // further. We'll just return NULL.
1071 MutexLockerEx x(Heap_lock);
1072 *gc_count_before_ret = total_collections();
1073 return NULL;
1074 }
1075 } else {
1076 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1077 MutexLockerEx x(Heap_lock);
1078 *gc_count_before_ret = total_collections();
1079 return NULL;
1080 }
1081 // The GCLocker is either active or the GCLocker initiated
1082 // GC has not yet been performed. Stall until it is and
1083 // then retry the allocation.
1084 GCLocker::stall_until_clear();
1085 (*gclocker_retry_count_ret) += 1;
1086 }
1087
1088 // We can reach here if we were unsuccessful in scheduling a
1089 // collection (because another thread beat us to it) or if we were
1090 // stalled due to the GC locker. In either can we should retry the
1091 // allocation attempt in case another thread successfully
1092 // performed a collection and reclaimed enough space. Give a
1093 // warning if we seem to be looping forever.
1094
1095 if ((QueuedAllocationWarningCount > 0) &&
1096 (try_count % QueuedAllocationWarningCount == 0)) {
1097 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1098 "retries %d times", try_count);
1099 }
1100 }
1101
1102 ShouldNotReachHere();
1103 return NULL;
1104 }
1105
1106 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1107 AllocationContext_t context,
1108 bool expect_null_mutator_alloc_region) {
1109 assert_at_safepoint(true /* should_be_vm_thread */);
1110 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1111 "the current alloc region was unexpectedly found to be non-NULL");
1112
1113 if (!is_humongous(word_size)) {
1114 return _allocator->attempt_allocation_locked(word_size, context);
1115 } else {
1116 HeapWord* result = humongous_obj_allocate(word_size, context);
1117 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1118 collector_state()->set_initiate_conc_mark_if_possible(true);
1119 }
1120 return result;
1121 }
1122
1123 ShouldNotReachHere();
1124 }
1125
1126 class PostMCRemSetClearClosure: public HeapRegionClosure {
1127 G1CollectedHeap* _g1h;
1128 ModRefBarrierSet* _mr_bs;
1129 public:
1130 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1131 _g1h(g1h), _mr_bs(mr_bs) {}
1132
1133 bool doHeapRegion(HeapRegion* r) {
1134 HeapRegionRemSet* hrrs = r->rem_set();
1135
1136 _g1h->reset_gc_time_stamps(r);
1137
1138 if (r->is_continues_humongous()) {
1139 // We'll assert that the strong code root list and RSet is empty
1140 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1141 assert(hrrs->occupied() == 0, "RSet should be empty");
1142 } else {
1143 hrrs->clear();
1144 }
1145 // You might think here that we could clear just the cards
1146 // corresponding to the used region. But no: if we leave a dirty card
1147 // in a region we might allocate into, then it would prevent that card
1148 // from being enqueued, and cause it to be missed.
1149 // Re: the performance cost: we shouldn't be doing full GC anyway!
1150 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1151
1152 return false;
1153 }
1154 };
1155
1156 void G1CollectedHeap::clear_rsets_post_compaction() {
1157 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1158 heap_region_iterate(&rs_clear);
1159 }
1160
1161 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1162 G1CollectedHeap* _g1h;
1163 UpdateRSOopClosure _cl;
1164 public:
1165 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1166 _cl(g1->g1_rem_set(), worker_i),
1167 _g1h(g1)
1168 { }
1169
1170 bool doHeapRegion(HeapRegion* r) {
1171 if (!r->is_continues_humongous()) {
1172 _cl.set_from(r);
1173 r->oop_iterate(&_cl);
1174 }
1175 return false;
1176 }
1177 };
1178
1179 class ParRebuildRSTask: public AbstractGangTask {
1180 G1CollectedHeap* _g1;
1181 HeapRegionClaimer _hrclaimer;
1182
1183 public:
1184 ParRebuildRSTask(G1CollectedHeap* g1) :
1185 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1186
1187 void work(uint worker_id) {
1188 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1189 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1190 }
1191 };
1192
1193 class PostCompactionPrinterClosure: public HeapRegionClosure {
1194 private:
1195 G1HRPrinter* _hr_printer;
1196 public:
1197 bool doHeapRegion(HeapRegion* hr) {
1198 assert(!hr->is_young(), "not expecting to find young regions");
1199 _hr_printer->post_compaction(hr);
1200 return false;
1201 }
1202
1203 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1204 : _hr_printer(hr_printer) { }
1205 };
1206
1207 void G1CollectedHeap::print_hrm_post_compaction() {
1208 if (_hr_printer.is_active()) {
1209 PostCompactionPrinterClosure cl(hr_printer());
1210 heap_region_iterate(&cl);
1211 }
1212
1213 }
1214
1215 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1216 bool clear_all_soft_refs) {
1217 assert_at_safepoint(true /* should_be_vm_thread */);
1218
1219 if (GCLocker::check_active_before_gc()) {
1220 return false;
1221 }
1222
1223 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1224 gc_timer->register_gc_start();
1225
1226 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1227 GCIdMark gc_id_mark;
1228 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1229
1230 SvcGCMarker sgcm(SvcGCMarker::FULL);
1231 ResourceMark rm;
1232
1233 print_heap_before_gc();
1234 print_heap_regions();
1235 trace_heap_before_gc(gc_tracer);
1236
1237 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1238
1239 _verifier->verify_region_sets_optional();
1240
1241 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1242 collector_policy()->should_clear_all_soft_refs();
1243
1244 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1245
1246 {
1247 IsGCActiveMark x;
1248
1249 // Timing
1250 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1251 GCTraceCPUTime tcpu;
1252
1253 {
1254 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1255 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1256 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1257
1258 G1HeapTransition heap_transition(this);
1259 g1_policy()->record_full_collection_start();
1260
1261 // Note: When we have a more flexible GC logging framework that
1262 // allows us to add optional attributes to a GC log record we
1263 // could consider timing and reporting how long we wait in the
1264 // following two methods.
1265 wait_while_free_regions_coming();
1266 // If we start the compaction before the CM threads finish
1267 // scanning the root regions we might trip them over as we'll
1268 // be moving objects / updating references. So let's wait until
1269 // they are done. By telling them to abort, they should complete
1270 // early.
1271 _cm->root_regions()->abort();
1272 _cm->root_regions()->wait_until_scan_finished();
1273 append_secondary_free_list_if_not_empty_with_lock();
1274
1275 gc_prologue(true);
1276 increment_total_collections(true /* full gc */);
1277 increment_old_marking_cycles_started();
1278
1279 assert(used() == recalculate_used(), "Should be equal");
1280
1281 _verifier->verify_before_gc();
1282
1283 _verifier->check_bitmaps("Full GC Start");
1284 pre_full_gc_dump(gc_timer);
1285
1286 #if defined(COMPILER2) || INCLUDE_JVMCI
1287 DerivedPointerTable::clear();
1288 #endif
1289
1290 // Disable discovery and empty the discovered lists
1291 // for the CM ref processor.
1292 ref_processor_cm()->disable_discovery();
1293 ref_processor_cm()->abandon_partial_discovery();
1294 ref_processor_cm()->verify_no_references_recorded();
1295
1296 // Abandon current iterations of concurrent marking and concurrent
1297 // refinement, if any are in progress.
1298 concurrent_mark()->abort();
1299
1300 // Make sure we'll choose a new allocation region afterwards.
1301 _allocator->release_mutator_alloc_region();
1302 _allocator->abandon_gc_alloc_regions();
1303 g1_rem_set()->cleanupHRRS();
1304
1305 // We may have added regions to the current incremental collection
1306 // set between the last GC or pause and now. We need to clear the
1307 // incremental collection set and then start rebuilding it afresh
1308 // after this full GC.
1309 abandon_collection_set(collection_set()->inc_head());
1310 collection_set()->clear_incremental();
1311 collection_set()->stop_incremental_building();
1312
1313 tear_down_region_sets(false /* free_list_only */);
1314 collector_state()->set_gcs_are_young(true);
1315
1316 // See the comments in g1CollectedHeap.hpp and
1317 // G1CollectedHeap::ref_processing_init() about
1318 // how reference processing currently works in G1.
1319
1320 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1321 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1322
1323 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1324 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1325
1326 ref_processor_stw()->enable_discovery();
1327 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1328
1329 // Do collection work
1330 {
1331 HandleMark hm; // Discard invalid handles created during gc
1332 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1333 }
1334
1335 assert(num_free_regions() == 0, "we should not have added any free regions");
1336 rebuild_region_sets(false /* free_list_only */);
1337
1338 // Enqueue any discovered reference objects that have
1339 // not been removed from the discovered lists.
1340 ref_processor_stw()->enqueue_discovered_references();
1341
1342 #if defined(COMPILER2) || INCLUDE_JVMCI
1343 DerivedPointerTable::update_pointers();
1344 #endif
1345
1346 MemoryService::track_memory_usage();
1347
1348 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1349 ref_processor_stw()->verify_no_references_recorded();
1350
1351 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1352 ClassLoaderDataGraph::purge();
1353 MetaspaceAux::verify_metrics();
1354
1355 // Note: since we've just done a full GC, concurrent
1356 // marking is no longer active. Therefore we need not
1357 // re-enable reference discovery for the CM ref processor.
1358 // That will be done at the start of the next marking cycle.
1359 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1360 ref_processor_cm()->verify_no_references_recorded();
1361
1362 reset_gc_time_stamp();
1363 // Since everything potentially moved, we will clear all remembered
1364 // sets, and clear all cards. Later we will rebuild remembered
1365 // sets. We will also reset the GC time stamps of the regions.
1366 clear_rsets_post_compaction();
1367 check_gc_time_stamps();
1368
1369 resize_if_necessary_after_full_collection();
1370
1371 // We should do this after we potentially resize the heap so
1372 // that all the COMMIT / UNCOMMIT events are generated before
1373 // the compaction events.
1374 print_hrm_post_compaction();
1375
1376 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1377 if (hot_card_cache->use_cache()) {
1378 hot_card_cache->reset_card_counts();
1379 hot_card_cache->reset_hot_cache();
1380 }
1381
1382 // Rebuild remembered sets of all regions.
1383 uint n_workers =
1384 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1385 workers()->active_workers(),
1386 Threads::number_of_non_daemon_threads());
1387 workers()->set_active_workers(n_workers);
1388
1389 ParRebuildRSTask rebuild_rs_task(this);
1390 workers()->run_task(&rebuild_rs_task);
1391
1392 // Rebuild the strong code root lists for each region
1393 rebuild_strong_code_roots();
1394
1395 if (true) { // FIXME
1396 MetaspaceGC::compute_new_size();
1397 }
1398
1399 #ifdef TRACESPINNING
1400 ParallelTaskTerminator::print_termination_counts();
1401 #endif
1402
1403 // Discard all rset updates
1404 JavaThread::dirty_card_queue_set().abandon_logs();
1405 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1406
1407 // At this point there should be no regions in the
1408 // entire heap tagged as young.
1409 assert(check_young_list_empty(true /* check_heap */),
1410 "young list should be empty at this point");
1411
1412 // Update the number of full collections that have been completed.
1413 increment_old_marking_cycles_completed(false /* concurrent */);
1414
1415 _hrm.verify_optional();
1416 _verifier->verify_region_sets_optional();
1417
1418 _verifier->verify_after_gc();
1419
1420 // Clear the previous marking bitmap, if needed for bitmap verification.
1421 // Note we cannot do this when we clear the next marking bitmap in
1422 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423 // objects marked during a full GC against the previous bitmap.
1424 // But we need to clear it before calling check_bitmaps below since
1425 // the full GC has compacted objects and updated TAMS but not updated
1426 // the prev bitmap.
1427 if (G1VerifyBitmaps) {
1428 _cm->clear_prev_bitmap(workers());
1429 }
1430 _verifier->check_bitmaps("Full GC End");
1431
1432 // Start a new incremental collection set for the next pause
1433 assert(collection_set()->head() == NULL, "must be");
1434 collection_set()->start_incremental_building();
1435
1436 clear_cset_fast_test();
1437
1438 _allocator->init_mutator_alloc_region();
1439
1440 g1_policy()->record_full_collection_end();
1441
1442 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1443 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1444 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1445 // before any GC notifications are raised.
1446 g1mm()->update_sizes();
1447
1448 gc_epilogue(true);
1449
1450 heap_transition.print();
1451
1452 print_heap_after_gc();
1453 print_heap_regions();
1454 trace_heap_after_gc(gc_tracer);
1455
1456 post_full_gc_dump(gc_timer);
1457 }
1458
1459 gc_timer->register_gc_end();
1460 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1461 }
1462
1463 return true;
1464 }
1465
1466 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1467 // Currently, there is no facility in the do_full_collection(bool) API to notify
1468 // the caller that the collection did not succeed (e.g., because it was locked
1469 // out by the GC locker). So, right now, we'll ignore the return value.
1470 bool dummy = do_full_collection(true, /* explicit_gc */
1471 clear_all_soft_refs);
1472 }
1473
1474 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1475 // Include bytes that will be pre-allocated to support collections, as "used".
1476 const size_t used_after_gc = used();
1477 const size_t capacity_after_gc = capacity();
1478 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1479
1480 // This is enforced in arguments.cpp.
1481 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1482 "otherwise the code below doesn't make sense");
1483
1484 // We don't have floating point command-line arguments
1485 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1486 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1487 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1488 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1489
1490 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1491 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1492
1493 // We have to be careful here as these two calculations can overflow
1494 // 32-bit size_t's.
1495 double used_after_gc_d = (double) used_after_gc;
1496 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1497 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1498
1499 // Let's make sure that they are both under the max heap size, which
1500 // by default will make them fit into a size_t.
1501 double desired_capacity_upper_bound = (double) max_heap_size;
1502 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1503 desired_capacity_upper_bound);
1504 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1505 desired_capacity_upper_bound);
1506
1507 // We can now safely turn them into size_t's.
1508 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1509 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1510
1511 // This assert only makes sense here, before we adjust them
1512 // with respect to the min and max heap size.
1513 assert(minimum_desired_capacity <= maximum_desired_capacity,
1514 "minimum_desired_capacity = " SIZE_FORMAT ", "
1515 "maximum_desired_capacity = " SIZE_FORMAT,
1516 minimum_desired_capacity, maximum_desired_capacity);
1517
1518 // Should not be greater than the heap max size. No need to adjust
1519 // it with respect to the heap min size as it's a lower bound (i.e.,
1520 // we'll try to make the capacity larger than it, not smaller).
1521 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1522 // Should not be less than the heap min size. No need to adjust it
1523 // with respect to the heap max size as it's an upper bound (i.e.,
1524 // we'll try to make the capacity smaller than it, not greater).
1525 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1526
1527 if (capacity_after_gc < minimum_desired_capacity) {
1528 // Don't expand unless it's significant
1529 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1530
1531 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1532 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1533 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1534
1535 expand(expand_bytes);
1536
1537 // No expansion, now see if we want to shrink
1538 } else if (capacity_after_gc > maximum_desired_capacity) {
1539 // Capacity too large, compute shrinking size
1540 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1541
1542 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1543 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1544 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1545
1546 shrink(shrink_bytes);
1547 }
1548 }
1549
1550 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1551 AllocationContext_t context,
1552 bool do_gc,
1553 bool clear_all_soft_refs,
1554 bool expect_null_mutator_alloc_region,
1555 bool* gc_succeeded) {
1556 *gc_succeeded = true;
1557 // Let's attempt the allocation first.
1558 HeapWord* result =
1559 attempt_allocation_at_safepoint(word_size,
1560 context,
1561 expect_null_mutator_alloc_region);
1562 if (result != NULL) {
1563 assert(*gc_succeeded, "sanity");
1564 return result;
1565 }
1566
1567 // In a G1 heap, we're supposed to keep allocation from failing by
1568 // incremental pauses. Therefore, at least for now, we'll favor
1569 // expansion over collection. (This might change in the future if we can
1570 // do something smarter than full collection to satisfy a failed alloc.)
1571 result = expand_and_allocate(word_size, context);
1572 if (result != NULL) {
1573 assert(*gc_succeeded, "sanity");
1574 return result;
1575 }
1576
1577 if (do_gc) {
1578 // Expansion didn't work, we'll try to do a Full GC.
1579 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1580 clear_all_soft_refs);
1581 }
1582
1583 return NULL;
1584 }
1585
1586 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1587 AllocationContext_t context,
1588 bool* succeeded) {
1589 assert_at_safepoint(true /* should_be_vm_thread */);
1590
1591 // Attempts to allocate followed by Full GC.
1592 HeapWord* result =
1593 satisfy_failed_allocation_helper(word_size,
1594 context,
1595 true, /* do_gc */
1596 false, /* clear_all_soft_refs */
1597 false, /* expect_null_mutator_alloc_region */
1598 succeeded);
1599
1600 if (result != NULL || !*succeeded) {
1601 return result;
1602 }
1603
1604 // Attempts to allocate followed by Full GC that will collect all soft references.
1605 result = satisfy_failed_allocation_helper(word_size,
1606 context,
1607 true, /* do_gc */
1608 true, /* clear_all_soft_refs */
1609 true, /* expect_null_mutator_alloc_region */
1610 succeeded);
1611
1612 if (result != NULL || !*succeeded) {
1613 return result;
1614 }
1615
1616 // Attempts to allocate, no GC
1617 result = satisfy_failed_allocation_helper(word_size,
1618 context,
1619 false, /* do_gc */
1620 false, /* clear_all_soft_refs */
1621 true, /* expect_null_mutator_alloc_region */
1622 succeeded);
1623
1624 if (result != NULL) {
1625 assert(*succeeded, "sanity");
1626 return result;
1627 }
1628
1629 assert(!collector_policy()->should_clear_all_soft_refs(),
1630 "Flag should have been handled and cleared prior to this point");
1631
1632 // What else? We might try synchronous finalization later. If the total
1633 // space available is large enough for the allocation, then a more
1634 // complete compaction phase than we've tried so far might be
1635 // appropriate.
1636 assert(*succeeded, "sanity");
1637 return NULL;
1638 }
1639
1640 // Attempting to expand the heap sufficiently
1641 // to support an allocation of the given "word_size". If
1642 // successful, perform the allocation and return the address of the
1643 // allocated block, or else "NULL".
1644
1645 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1646 assert_at_safepoint(true /* should_be_vm_thread */);
1647
1648 _verifier->verify_region_sets_optional();
1649
1650 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1651 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1652 word_size * HeapWordSize);
1653
1654
1655 if (expand(expand_bytes)) {
1656 _hrm.verify_optional();
1657 _verifier->verify_region_sets_optional();
1658 return attempt_allocation_at_safepoint(word_size,
1659 context,
1660 false /* expect_null_mutator_alloc_region */);
1661 }
1662 return NULL;
1663 }
1664
1665 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1666 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1667 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1668 HeapRegion::GrainBytes);
1669
1670 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1671 expand_bytes, aligned_expand_bytes);
1672
1673 if (is_maximal_no_gc()) {
1674 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1675 return false;
1676 }
1677
1678 double expand_heap_start_time_sec = os::elapsedTime();
1679 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1680 assert(regions_to_expand > 0, "Must expand by at least one region");
1681
1682 uint expanded_by = _hrm.expand_by(regions_to_expand);
1683 if (expand_time_ms != NULL) {
1684 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1685 }
1686
1687 if (expanded_by > 0) {
1688 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1689 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1690 g1_policy()->record_new_heap_size(num_regions());
1691 } else {
1692 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1693
1694 // The expansion of the virtual storage space was unsuccessful.
1695 // Let's see if it was because we ran out of swap.
1696 if (G1ExitOnExpansionFailure &&
1697 _hrm.available() >= regions_to_expand) {
1698 // We had head room...
1699 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1700 }
1701 }
1702 return regions_to_expand > 0;
1703 }
1704
1705 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1706 size_t aligned_shrink_bytes =
1707 ReservedSpace::page_align_size_down(shrink_bytes);
1708 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1709 HeapRegion::GrainBytes);
1710 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1711
1712 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1713 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1714
1715
1716 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",
1717 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1718 if (num_regions_removed > 0) {
1719 g1_policy()->record_new_heap_size(num_regions());
1720 } else {
1721 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1722 }
1723 }
1724
1725 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1726 _verifier->verify_region_sets_optional();
1727
1728 // We should only reach here at the end of a Full GC which means we
1729 // should not not be holding to any GC alloc regions. The method
1730 // below will make sure of that and do any remaining clean up.
1731 _allocator->abandon_gc_alloc_regions();
1732
1733 // Instead of tearing down / rebuilding the free lists here, we
1734 // could instead use the remove_all_pending() method on free_list to
1735 // remove only the ones that we need to remove.
1736 tear_down_region_sets(true /* free_list_only */);
1737 shrink_helper(shrink_bytes);
1738 rebuild_region_sets(true /* free_list_only */);
1739
1740 _hrm.verify_optional();
1741 _verifier->verify_region_sets_optional();
1742 }
1743
1744 // Public methods.
1745
1746 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1747 CollectedHeap(),
1748 _g1_policy(policy_),
1749 _collection_set(this),
1750 _dirty_card_queue_set(false),
1751 _is_alive_closure_cm(this),
1752 _is_alive_closure_stw(this),
1753 _ref_processor_cm(NULL),
1754 _ref_processor_stw(NULL),
1755 _bot(NULL),
1756 _cg1r(NULL),
1757 _g1mm(NULL),
1758 _refine_cte_cl(NULL),
1759 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1760 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1761 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1762 _humongous_reclaim_candidates(),
1763 _has_humongous_reclaim_candidates(false),
1764 _archive_allocator(NULL),
1765 _free_regions_coming(false),
1766 _young_list(new YoungList(this)),
1767 _gc_time_stamp(0),
1768 _summary_bytes_used(0),
1769 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1770 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1771 _expand_heap_after_alloc_failure(true),
1772 _old_marking_cycles_started(0),
1773 _old_marking_cycles_completed(0),
1774 _in_cset_fast_test(),
1775 _dirty_cards_region_list(NULL),
1776 _worker_cset_start_region(NULL),
1777 _worker_cset_start_region_time_stamp(NULL),
1778 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1779 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1780
1781 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1782 /* are_GC_task_threads */true,
1783 /* are_ConcurrentGC_threads */false);
1784 _workers->initialize_workers();
1785 _verifier = new G1HeapVerifier(this);
1786
1787 _allocator = G1Allocator::create_allocator(this);
1788
1789 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1790
1791 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1792
1793 // Override the default _filler_array_max_size so that no humongous filler
1794 // objects are created.
1795 _filler_array_max_size = _humongous_object_threshold_in_words;
1796
1797 uint n_queues = ParallelGCThreads;
1798 _task_queues = new RefToScanQueueSet(n_queues);
1799
1800 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1801 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1802 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1803
1804 for (uint i = 0; i < n_queues; i++) {
1805 RefToScanQueue* q = new RefToScanQueue();
1806 q->initialize();
1807 _task_queues->register_queue(i, q);
1808 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1809 }
1810 clear_cset_start_regions();
1811
1812 // Initialize the G1EvacuationFailureALot counters and flags.
1813 NOT_PRODUCT(reset_evacuation_should_fail();)
1814
1815 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1816 }
1817
1818 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1819 size_t size,
1820 size_t translation_factor) {
1821 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1822 // Allocate a new reserved space, preferring to use large pages.
1823 ReservedSpace rs(size, preferred_page_size);
1824 G1RegionToSpaceMapper* result =
1825 G1RegionToSpaceMapper::create_mapper(rs,
1826 size,
1827 rs.alignment(),
1828 HeapRegion::GrainBytes,
1829 translation_factor,
1830 mtGC);
1831 if (TracePageSizes) {
1832 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1833 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1834 }
1835 return result;
1836 }
1837
1838 jint G1CollectedHeap::initialize() {
1839 CollectedHeap::pre_initialize();
1840 os::enable_vtime();
1841
1842 // Necessary to satisfy locking discipline assertions.
1843
1844 MutexLocker x(Heap_lock);
1845
1846 // While there are no constraints in the GC code that HeapWordSize
1847 // be any particular value, there are multiple other areas in the
1848 // system which believe this to be true (e.g. oop->object_size in some
1849 // cases incorrectly returns the size in wordSize units rather than
1850 // HeapWordSize).
1851 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1852
1853 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1854 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1855 size_t heap_alignment = collector_policy()->heap_alignment();
1856
1857 // Ensure that the sizes are properly aligned.
1858 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1859 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1860 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1861
1862 _refine_cte_cl = new RefineCardTableEntryClosure();
1863
1864 jint ecode = JNI_OK;
1865 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1866 if (_cg1r == NULL) {
1867 return ecode;
1868 }
1869
1870 // Reserve the maximum.
1871
1872 // When compressed oops are enabled, the preferred heap base
1873 // is calculated by subtracting the requested size from the
1874 // 32Gb boundary and using the result as the base address for
1875 // heap reservation. If the requested size is not aligned to
1876 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1877 // into the ReservedHeapSpace constructor) then the actual
1878 // base of the reserved heap may end up differing from the
1879 // address that was requested (i.e. the preferred heap base).
1880 // If this happens then we could end up using a non-optimal
1881 // compressed oops mode.
1882
1883 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1884 heap_alignment);
1885
1886 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1887
1888 // Create the barrier set for the entire reserved region.
1889 G1SATBCardTableLoggingModRefBS* bs
1890 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1891 bs->initialize();
1892 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1893 set_barrier_set(bs);
1894
1895 // Also create a G1 rem set.
1896 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1897
1898 // Carve out the G1 part of the heap.
1899 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1900 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1901 G1RegionToSpaceMapper* heap_storage =
1902 G1RegionToSpaceMapper::create_mapper(g1_rs,
1903 g1_rs.size(),
1904 page_size,
1905 HeapRegion::GrainBytes,
1906 1,
1907 mtJavaHeap);
1908 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1909 max_byte_size, page_size,
1910 heap_rs.base(),
1911 heap_rs.size());
1912 heap_storage->set_mapping_changed_listener(&_listener);
1913
1914 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1915 G1RegionToSpaceMapper* bot_storage =
1916 create_aux_memory_mapper("Block offset table",
1917 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1918 G1BlockOffsetTable::heap_map_factor());
1919
1920 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1921 G1RegionToSpaceMapper* cardtable_storage =
1922 create_aux_memory_mapper("Card table",
1923 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1924 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1925
1926 G1RegionToSpaceMapper* card_counts_storage =
1927 create_aux_memory_mapper("Card counts table",
1928 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1929 G1CardCounts::heap_map_factor());
1930
1931 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1932 G1RegionToSpaceMapper* prev_bitmap_storage =
1933 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1934 G1RegionToSpaceMapper* next_bitmap_storage =
1935 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1936
1937 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1938 g1_barrier_set()->initialize(cardtable_storage);
1939 // Do later initialization work for concurrent refinement.
1940 _cg1r->init(card_counts_storage);
1941
1942 // 6843694 - ensure that the maximum region index can fit
1943 // in the remembered set structures.
1944 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1945 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1946
1947 G1RemSet::initialize(max_regions());
1948
1949 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1950 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1951 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1952 "too many cards per region");
1953
1954 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1955
1956 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1957
1958 {
1959 HeapWord* start = _hrm.reserved().start();
1960 HeapWord* end = _hrm.reserved().end();
1961 size_t granularity = HeapRegion::GrainBytes;
1962
1963 _in_cset_fast_test.initialize(start, end, granularity);
1964 _humongous_reclaim_candidates.initialize(start, end, granularity);
1965 }
1966
1967 // Create the G1ConcurrentMark data structure and thread.
1968 // (Must do this late, so that "max_regions" is defined.)
1969 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1970 if (_cm == NULL || !_cm->completed_initialization()) {
1971 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1972 return JNI_ENOMEM;
1973 }
1974 _cmThread = _cm->cmThread();
1975
1976 // Now expand into the initial heap size.
1977 if (!expand(init_byte_size)) {
1978 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1979 return JNI_ENOMEM;
1980 }
1981
1982 // Perform any initialization actions delegated to the policy.
1983 g1_policy()->init();
1984
1985 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1986 SATB_Q_FL_lock,
1987 G1SATBProcessCompletedThreshold,
1988 Shared_SATB_Q_lock);
1989
1990 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1991 DirtyCardQ_CBL_mon,
1992 DirtyCardQ_FL_lock,
1993 (int)concurrent_g1_refine()->yellow_zone(),
1994 (int)concurrent_g1_refine()->red_zone(),
1995 Shared_DirtyCardQ_lock,
1996 NULL, // fl_owner
1997 true); // init_free_ids
1998
1999 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2000 DirtyCardQ_CBL_mon,
2001 DirtyCardQ_FL_lock,
2002 -1, // never trigger processing
2003 -1, // no limit on length
2004 Shared_DirtyCardQ_lock,
2005 &JavaThread::dirty_card_queue_set());
2006
2007 // Here we allocate the dummy HeapRegion that is required by the
2008 // G1AllocRegion class.
2009 HeapRegion* dummy_region = _hrm.get_dummy_region();
2010
2011 // We'll re-use the same region whether the alloc region will
2012 // require BOT updates or not and, if it doesn't, then a non-young
2013 // region will complain that it cannot support allocations without
2014 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2015 dummy_region->set_eden();
2016 // Make sure it's full.
2017 dummy_region->set_top(dummy_region->end());
2018 G1AllocRegion::setup(this, dummy_region);
2019
2020 _allocator->init_mutator_alloc_region();
2021
2022 // Do create of the monitoring and management support so that
2023 // values in the heap have been properly initialized.
2024 _g1mm = new G1MonitoringSupport(this);
2025
2026 G1StringDedup::initialize();
2027
2028 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2029 for (uint i = 0; i < ParallelGCThreads; i++) {
2030 new (&_preserved_objs[i]) OopAndMarkOopStack();
2031 }
2032
2033 return JNI_OK;
2034 }
2035
2036 void G1CollectedHeap::stop() {
2037 // Stop all concurrent threads. We do this to make sure these threads
2038 // do not continue to execute and access resources (e.g. logging)
2039 // that are destroyed during shutdown.
2040 _cg1r->stop();
2041 _cmThread->stop();
2042 if (G1StringDedup::is_enabled()) {
2043 G1StringDedup::stop();
2044 }
2045 }
2046
2047 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2048 return HeapRegion::max_region_size();
2049 }
2050
2051 void G1CollectedHeap::post_initialize() {
2052 CollectedHeap::post_initialize();
2053 ref_processing_init();
2054 }
2055
2056 void G1CollectedHeap::ref_processing_init() {
2057 // Reference processing in G1 currently works as follows:
2058 //
2059 // * There are two reference processor instances. One is
2060 // used to record and process discovered references
2061 // during concurrent marking; the other is used to
2062 // record and process references during STW pauses
2063 // (both full and incremental).
2064 // * Both ref processors need to 'span' the entire heap as
2065 // the regions in the collection set may be dotted around.
2066 //
2067 // * For the concurrent marking ref processor:
2068 // * Reference discovery is enabled at initial marking.
2069 // * Reference discovery is disabled and the discovered
2070 // references processed etc during remarking.
2071 // * Reference discovery is MT (see below).
2072 // * Reference discovery requires a barrier (see below).
2073 // * Reference processing may or may not be MT
2074 // (depending on the value of ParallelRefProcEnabled
2075 // and ParallelGCThreads).
2076 // * A full GC disables reference discovery by the CM
2077 // ref processor and abandons any entries on it's
2078 // discovered lists.
2079 //
2080 // * For the STW processor:
2081 // * Non MT discovery is enabled at the start of a full GC.
2082 // * Processing and enqueueing during a full GC is non-MT.
2083 // * During a full GC, references are processed after marking.
2084 //
2085 // * Discovery (may or may not be MT) is enabled at the start
2086 // of an incremental evacuation pause.
2087 // * References are processed near the end of a STW evacuation pause.
2088 // * For both types of GC:
2089 // * Discovery is atomic - i.e. not concurrent.
2090 // * Reference discovery will not need a barrier.
2091
2092 MemRegion mr = reserved_region();
2093
2094 // Concurrent Mark ref processor
2095 _ref_processor_cm =
2096 new ReferenceProcessor(mr, // span
2097 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2098 // mt processing
2099 ParallelGCThreads,
2100 // degree of mt processing
2101 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2102 // mt discovery
2103 MAX2(ParallelGCThreads, ConcGCThreads),
2104 // degree of mt discovery
2105 false,
2106 // Reference discovery is not atomic
2107 &_is_alive_closure_cm);
2108 // is alive closure
2109 // (for efficiency/performance)
2110
2111 // STW ref processor
2112 _ref_processor_stw =
2113 new ReferenceProcessor(mr, // span
2114 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2115 // mt processing
2116 ParallelGCThreads,
2117 // degree of mt processing
2118 (ParallelGCThreads > 1),
2119 // mt discovery
2120 ParallelGCThreads,
2121 // degree of mt discovery
2122 true,
2123 // Reference discovery is atomic
2124 &_is_alive_closure_stw);
2125 // is alive closure
2126 // (for efficiency/performance)
2127 }
2128
2129 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2130 return g1_policy();
2131 }
2132
2133 size_t G1CollectedHeap::capacity() const {
2134 return _hrm.length() * HeapRegion::GrainBytes;
2135 }
2136
2137 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2138 hr->reset_gc_time_stamp();
2139 }
2140
2141 #ifndef PRODUCT
2142
2143 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2144 private:
2145 unsigned _gc_time_stamp;
2146 bool _failures;
2147
2148 public:
2149 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2150 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2151
2152 virtual bool doHeapRegion(HeapRegion* hr) {
2153 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2154 if (_gc_time_stamp != region_gc_time_stamp) {
2155 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2156 region_gc_time_stamp, _gc_time_stamp);
2157 _failures = true;
2158 }
2159 return false;
2160 }
2161
2162 bool failures() { return _failures; }
2163 };
2164
2165 void G1CollectedHeap::check_gc_time_stamps() {
2166 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2167 heap_region_iterate(&cl);
2168 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2169 }
2170 #endif // PRODUCT
2171
2172 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2173 _cg1r->hot_card_cache()->drain(cl, worker_i);
2174 }
2175
2176 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2177 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2178 size_t n_completed_buffers = 0;
2179 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2180 n_completed_buffers++;
2181 }
2182 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2183 dcqs.clear_n_completed_buffers();
2184 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2185 }
2186
2187 // Computes the sum of the storage used by the various regions.
2188 size_t G1CollectedHeap::used() const {
2189 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2190 if (_archive_allocator != NULL) {
2191 result += _archive_allocator->used();
2192 }
2193 return result;
2194 }
2195
2196 size_t G1CollectedHeap::used_unlocked() const {
2197 return _summary_bytes_used;
2198 }
2199
2200 class SumUsedClosure: public HeapRegionClosure {
2201 size_t _used;
2202 public:
2203 SumUsedClosure() : _used(0) {}
2204 bool doHeapRegion(HeapRegion* r) {
2205 _used += r->used();
2206 return false;
2207 }
2208 size_t result() { return _used; }
2209 };
2210
2211 size_t G1CollectedHeap::recalculate_used() const {
2212 double recalculate_used_start = os::elapsedTime();
2213
2214 SumUsedClosure blk;
2215 heap_region_iterate(&blk);
2216
2217 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2218 return blk.result();
2219 }
2220
2221 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2222 switch (cause) {
2223 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2224 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2225 case GCCause::_update_allocation_context_stats_inc: return true;
2226 case GCCause::_wb_conc_mark: return true;
2227 default : return false;
2228 }
2229 }
2230
2231 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2232 switch (cause) {
2233 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2234 case GCCause::_g1_humongous_allocation: return true;
2235 default: return is_user_requested_concurrent_full_gc(cause);
2236 }
2237 }
2238
2239 #ifndef PRODUCT
2240 void G1CollectedHeap::allocate_dummy_regions() {
2241 // Let's fill up most of the region
2242 size_t word_size = HeapRegion::GrainWords - 1024;
2243 // And as a result the region we'll allocate will be humongous.
2244 guarantee(is_humongous(word_size), "sanity");
2245
2246 // _filler_array_max_size is set to humongous object threshold
2247 // but temporarily change it to use CollectedHeap::fill_with_object().
2248 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2249
2250 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2251 // Let's use the existing mechanism for the allocation
2252 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2253 AllocationContext::system());
2254 if (dummy_obj != NULL) {
2255 MemRegion mr(dummy_obj, word_size);
2256 CollectedHeap::fill_with_object(mr);
2257 } else {
2258 // If we can't allocate once, we probably cannot allocate
2259 // again. Let's get out of the loop.
2260 break;
2261 }
2262 }
2263 }
2264 #endif // !PRODUCT
2265
2266 void G1CollectedHeap::increment_old_marking_cycles_started() {
2267 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2268 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2269 "Wrong marking cycle count (started: %d, completed: %d)",
2270 _old_marking_cycles_started, _old_marking_cycles_completed);
2271
2272 _old_marking_cycles_started++;
2273 }
2274
2275 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2276 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2277
2278 // We assume that if concurrent == true, then the caller is a
2279 // concurrent thread that was joined the Suspendible Thread
2280 // Set. If there's ever a cheap way to check this, we should add an
2281 // assert here.
2282
2283 // Given that this method is called at the end of a Full GC or of a
2284 // concurrent cycle, and those can be nested (i.e., a Full GC can
2285 // interrupt a concurrent cycle), the number of full collections
2286 // completed should be either one (in the case where there was no
2287 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2288 // behind the number of full collections started.
2289
2290 // This is the case for the inner caller, i.e. a Full GC.
2291 assert(concurrent ||
2292 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2293 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2294 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2295 "is inconsistent with _old_marking_cycles_completed = %u",
2296 _old_marking_cycles_started, _old_marking_cycles_completed);
2297
2298 // This is the case for the outer caller, i.e. the concurrent cycle.
2299 assert(!concurrent ||
2300 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2301 "for outer caller (concurrent cycle): "
2302 "_old_marking_cycles_started = %u "
2303 "is inconsistent with _old_marking_cycles_completed = %u",
2304 _old_marking_cycles_started, _old_marking_cycles_completed);
2305
2306 _old_marking_cycles_completed += 1;
2307
2308 // We need to clear the "in_progress" flag in the CM thread before
2309 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2310 // is set) so that if a waiter requests another System.gc() it doesn't
2311 // incorrectly see that a marking cycle is still in progress.
2312 if (concurrent) {
2313 _cmThread->set_idle();
2314 }
2315
2316 // This notify_all() will ensure that a thread that called
2317 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2318 // and it's waiting for a full GC to finish will be woken up. It is
2319 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2320 FullGCCount_lock->notify_all();
2321 }
2322
2323 void G1CollectedHeap::collect(GCCause::Cause cause) {
2324 assert_heap_not_locked();
2325
2326 uint gc_count_before;
2327 uint old_marking_count_before;
2328 uint full_gc_count_before;
2329 bool retry_gc;
2330
2331 do {
2332 retry_gc = false;
2333
2334 {
2335 MutexLocker ml(Heap_lock);
2336
2337 // Read the GC count while holding the Heap_lock
2338 gc_count_before = total_collections();
2339 full_gc_count_before = total_full_collections();
2340 old_marking_count_before = _old_marking_cycles_started;
2341 }
2342
2343 if (should_do_concurrent_full_gc(cause)) {
2344 // Schedule an initial-mark evacuation pause that will start a
2345 // concurrent cycle. We're setting word_size to 0 which means that
2346 // we are not requesting a post-GC allocation.
2347 VM_G1IncCollectionPause op(gc_count_before,
2348 0, /* word_size */
2349 true, /* should_initiate_conc_mark */
2350 g1_policy()->max_pause_time_ms(),
2351 cause);
2352 op.set_allocation_context(AllocationContext::current());
2353
2354 VMThread::execute(&op);
2355 if (!op.pause_succeeded()) {
2356 if (old_marking_count_before == _old_marking_cycles_started) {
2357 retry_gc = op.should_retry_gc();
2358 } else {
2359 // A Full GC happened while we were trying to schedule the
2360 // initial-mark GC. No point in starting a new cycle given
2361 // that the whole heap was collected anyway.
2362 }
2363
2364 if (retry_gc) {
2365 if (GCLocker::is_active_and_needs_gc()) {
2366 GCLocker::stall_until_clear();
2367 }
2368 }
2369 }
2370 } else {
2371 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2372 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2373
2374 // Schedule a standard evacuation pause. We're setting word_size
2375 // to 0 which means that we are not requesting a post-GC allocation.
2376 VM_G1IncCollectionPause op(gc_count_before,
2377 0, /* word_size */
2378 false, /* should_initiate_conc_mark */
2379 g1_policy()->max_pause_time_ms(),
2380 cause);
2381 VMThread::execute(&op);
2382 } else {
2383 // Schedule a Full GC.
2384 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2385 VMThread::execute(&op);
2386 }
2387 }
2388 } while (retry_gc);
2389 }
2390
2391 bool G1CollectedHeap::is_in(const void* p) const {
2392 if (_hrm.reserved().contains(p)) {
2393 // Given that we know that p is in the reserved space,
2394 // heap_region_containing() should successfully
2395 // return the containing region.
2396 HeapRegion* hr = heap_region_containing(p);
2397 return hr->is_in(p);
2398 } else {
2399 return false;
2400 }
2401 }
2402
2403 #ifdef ASSERT
2404 bool G1CollectedHeap::is_in_exact(const void* p) const {
2405 bool contains = reserved_region().contains(p);
2406 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2407 if (contains && available) {
2408 return true;
2409 } else {
2410 return false;
2411 }
2412 }
2413 #endif
2414
2415 bool G1CollectedHeap::obj_in_cs(oop obj) {
2416 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2417 return r != NULL && r->in_collection_set();
2418 }
2419
2420 // Iteration functions.
2421
2422 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2423
2424 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2425 ExtendedOopClosure* _cl;
2426 public:
2427 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2428 bool doHeapRegion(HeapRegion* r) {
2429 if (!r->is_continues_humongous()) {
2430 r->oop_iterate(_cl);
2431 }
2432 return false;
2433 }
2434 };
2435
2436 // Iterates an ObjectClosure over all objects within a HeapRegion.
2437
2438 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2439 ObjectClosure* _cl;
2440 public:
2441 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2442 bool doHeapRegion(HeapRegion* r) {
2443 if (!r->is_continues_humongous()) {
2444 r->object_iterate(_cl);
2445 }
2446 return false;
2447 }
2448 };
2449
2450 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2451 IterateObjectClosureRegionClosure blk(cl);
2452 heap_region_iterate(&blk);
2453 }
2454
2455 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2456 _hrm.iterate(cl);
2457 }
2458
2459 void
2460 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2461 uint worker_id,
2462 HeapRegionClaimer *hrclaimer,
2463 bool concurrent) const {
2464 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2465 }
2466
2467 // Clear the cached CSet starting regions and (more importantly)
2468 // the time stamps. Called when we reset the GC time stamp.
2469 void G1CollectedHeap::clear_cset_start_regions() {
2470 assert(_worker_cset_start_region != NULL, "sanity");
2471 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2472
2473 for (uint i = 0; i < ParallelGCThreads; i++) {
2474 _worker_cset_start_region[i] = NULL;
2475 _worker_cset_start_region_time_stamp[i] = 0;
2476 }
2477 }
2478
2479 // Given the id of a worker, obtain or calculate a suitable
2480 // starting region for iterating over the current collection set.
2481 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2482 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2483
2484 HeapRegion* result = NULL;
2485 unsigned gc_time_stamp = get_gc_time_stamp();
2486
2487 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2488 // Cached starting region for current worker was set
2489 // during the current pause - so it's valid.
2490 // Note: the cached starting heap region may be NULL
2491 // (when the collection set is empty).
2492 result = _worker_cset_start_region[worker_i];
2493 assert(result == NULL || result->in_collection_set(), "sanity");
2494 return result;
2495 }
2496
2497 // The cached entry was not valid so let's calculate
2498 // a suitable starting heap region for this worker.
2499
2500 // We want the parallel threads to start their collection
2501 // set iteration at different collection set regions to
2502 // avoid contention.
2503 // If we have:
2504 // n collection set regions
2505 // p threads
2506 // Then thread t will start at region floor ((t * n) / p)
2507
2508 result = collection_set()->head();
2509 uint cs_size = collection_set()->region_length();
2510 uint active_workers = workers()->active_workers();
2511
2512 uint end_ind = (cs_size * worker_i) / active_workers;
2513 uint start_ind = 0;
2514
2515 if (worker_i > 0 &&
2516 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2517 // Previous workers starting region is valid
2518 // so let's iterate from there
2519 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2520 OrderAccess::loadload();
2521 result = _worker_cset_start_region[worker_i - 1];
2522 }
2523
2524 for (uint i = start_ind; i < end_ind; i++) {
2525 result = result->next_in_collection_set();
2526 }
2527
2528 // Note: the calculated starting heap region may be NULL
2529 // (when the collection set is empty).
2530 assert(result == NULL || result->in_collection_set(), "sanity");
2531 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2532 "should be updated only once per pause");
2533 _worker_cset_start_region[worker_i] = result;
2534 OrderAccess::storestore();
2535 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2536 return result;
2537 }
2538
2539 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2540 HeapRegion* r = collection_set()->head();
2541 while (r != NULL) {
2542 HeapRegion* next = r->next_in_collection_set();
2543 if (cl->doHeapRegion(r)) {
2544 cl->incomplete();
2545 return;
2546 }
2547 r = next;
2548 }
2549 }
2550
2551 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2552 HeapRegionClosure *cl) {
2553 if (r == NULL) {
2554 // The CSet is empty so there's nothing to do.
2555 return;
2556 }
2557
2558 assert(r->in_collection_set(),
2559 "Start region must be a member of the collection set.");
2560 HeapRegion* cur = r;
2561 while (cur != NULL) {
2562 HeapRegion* next = cur->next_in_collection_set();
2563 if (cl->doHeapRegion(cur) && false) {
2564 cl->incomplete();
2565 return;
2566 }
2567 cur = next;
2568 }
2569 cur = collection_set()->head();
2570 while (cur != r) {
2571 HeapRegion* next = cur->next_in_collection_set();
2572 if (cl->doHeapRegion(cur) && false) {
2573 cl->incomplete();
2574 return;
2575 }
2576 cur = next;
2577 }
2578 }
2579
2580 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2581 HeapRegion* result = _hrm.next_region_in_heap(from);
2582 while (result != NULL && result->is_pinned()) {
2583 result = _hrm.next_region_in_heap(result);
2584 }
2585 return result;
2586 }
2587
2588 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2589 HeapRegion* hr = heap_region_containing(addr);
2590 return hr->block_start(addr);
2591 }
2592
2593 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2594 HeapRegion* hr = heap_region_containing(addr);
2595 return hr->block_size(addr);
2596 }
2597
2598 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2599 HeapRegion* hr = heap_region_containing(addr);
2600 return hr->block_is_obj(addr);
2601 }
2602
2603 bool G1CollectedHeap::supports_tlab_allocation() const {
2604 return true;
2605 }
2606
2607 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2608 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2609 }
2610
2611 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2612 return young_list()->eden_used_bytes();
2613 }
2614
2615 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2616 // must be equal to the humongous object limit.
2617 size_t G1CollectedHeap::max_tlab_size() const {
2618 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2619 }
2620
2621 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2622 AllocationContext_t context = AllocationContext::current();
2623 return _allocator->unsafe_max_tlab_alloc(context);
2624 }
2625
2626 size_t G1CollectedHeap::max_capacity() const {
2627 return _hrm.reserved().byte_size();
2628 }
2629
2630 jlong G1CollectedHeap::millis_since_last_gc() {
2631 // assert(false, "NYI");
2632 return 0;
2633 }
2634
2635 void G1CollectedHeap::prepare_for_verify() {
2636 _verifier->prepare_for_verify();
2637 }
2638
2639 void G1CollectedHeap::verify(VerifyOption vo) {
2640 _verifier->verify(vo);
2641 }
2642
2643 class PrintRegionClosure: public HeapRegionClosure {
2644 outputStream* _st;
2645 public:
2646 PrintRegionClosure(outputStream* st) : _st(st) {}
2647 bool doHeapRegion(HeapRegion* r) {
2648 r->print_on(_st);
2649 return false;
2650 }
2651 };
2652
2653 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2654 const HeapRegion* hr,
2655 const VerifyOption vo) const {
2656 switch (vo) {
2657 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2658 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2659 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2660 default: ShouldNotReachHere();
2661 }
2662 return false; // keep some compilers happy
2663 }
2664
2665 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2666 const VerifyOption vo) const {
2667 switch (vo) {
2668 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2669 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2670 case VerifyOption_G1UseMarkWord: {
2671 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2672 return !obj->is_gc_marked() && !hr->is_archive();
2673 }
2674 default: ShouldNotReachHere();
2675 }
2676 return false; // keep some compilers happy
2677 }
2678
2679 void G1CollectedHeap::print_heap_regions() const {
2680 Log(gc, heap, region) log;
2681 if (log.is_trace()) {
2682 ResourceMark rm;
2683 print_regions_on(log.trace_stream());
2684 }
2685 }
2686
2687 void G1CollectedHeap::print_on(outputStream* st) const {
2688 st->print(" %-20s", "garbage-first heap");
2689 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2690 capacity()/K, used_unlocked()/K);
2691 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2692 p2i(_hrm.reserved().start()),
2693 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2694 p2i(_hrm.reserved().end()));
2695 st->cr();
2696 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2697 uint young_regions = _young_list->length();
2698 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2699 (size_t) young_regions * HeapRegion::GrainBytes / K);
2700 uint survivor_regions = _young_list->survivor_length();
2701 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2702 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2703 st->cr();
2704 MetaspaceAux::print_on(st);
2705 }
2706
2707 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2708 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2709 "HS=humongous(starts), HC=humongous(continues), "
2710 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2711 "AC=allocation context, "
2712 "TAMS=top-at-mark-start (previous, next)");
2713 PrintRegionClosure blk(st);
2714 heap_region_iterate(&blk);
2715 }
2716
2717 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2718 print_on(st);
2719
2720 // Print the per-region information.
2721 print_regions_on(st);
2722 }
2723
2724 void G1CollectedHeap::print_on_error(outputStream* st) const {
2725 this->CollectedHeap::print_on_error(st);
2726
2727 if (_cm != NULL) {
2728 st->cr();
2729 _cm->print_on_error(st);
2730 }
2731 }
2732
2733 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2734 workers()->print_worker_threads_on(st);
2735 _cmThread->print_on(st);
2736 st->cr();
2737 _cm->print_worker_threads_on(st);
2738 _cg1r->print_worker_threads_on(st);
2739 if (G1StringDedup::is_enabled()) {
2740 G1StringDedup::print_worker_threads_on(st);
2741 }
2742 }
2743
2744 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2745 workers()->threads_do(tc);
2746 tc->do_thread(_cmThread);
2747 _cg1r->threads_do(tc);
2748 if (G1StringDedup::is_enabled()) {
2749 G1StringDedup::threads_do(tc);
2750 }
2751 }
2752
2753 void G1CollectedHeap::print_tracing_info() const {
2754 g1_rem_set()->print_summary_info();
2755 concurrent_mark()->print_summary_info();
2756 g1_policy()->print_yg_surv_rate_info();
2757 }
2758
2759 #ifndef PRODUCT
2760 // Helpful for debugging RSet issues.
2761
2762 class PrintRSetsClosure : public HeapRegionClosure {
2763 private:
2764 const char* _msg;
2765 size_t _occupied_sum;
2766
2767 public:
2768 bool doHeapRegion(HeapRegion* r) {
2769 HeapRegionRemSet* hrrs = r->rem_set();
2770 size_t occupied = hrrs->occupied();
2771 _occupied_sum += occupied;
2772
2773 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2774 if (occupied == 0) {
2775 tty->print_cr(" RSet is empty");
2776 } else {
2777 hrrs->print();
2778 }
2779 tty->print_cr("----------");
2780 return false;
2781 }
2782
2783 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2784 tty->cr();
2785 tty->print_cr("========================================");
2786 tty->print_cr("%s", msg);
2787 tty->cr();
2788 }
2789
2790 ~PrintRSetsClosure() {
2791 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2792 tty->print_cr("========================================");
2793 tty->cr();
2794 }
2795 };
2796
2797 void G1CollectedHeap::print_cset_rsets() {
2798 PrintRSetsClosure cl("Printing CSet RSets");
2799 collection_set_iterate(&cl);
2800 }
2801
2802 void G1CollectedHeap::print_all_rsets() {
2803 PrintRSetsClosure cl("Printing All RSets");;
2804 heap_region_iterate(&cl);
2805 }
2806 #endif // PRODUCT
2807
2808 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2809 YoungList* young_list = heap()->young_list();
2810
2811 size_t eden_used_bytes = young_list->eden_used_bytes();
2812 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2813 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2814
2815 size_t eden_capacity_bytes =
2816 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2817
2818 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2819 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2820 eden_capacity_bytes, survivor_used_bytes, num_regions());
2821 }
2822
2823 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2824 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2825 stats->unused(), stats->used(), stats->region_end_waste(),
2826 stats->regions_filled(), stats->direct_allocated(),
2827 stats->failure_used(), stats->failure_waste());
2828 }
2829
2830 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2831 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2832 gc_tracer->report_gc_heap_summary(when, heap_summary);
2833
2834 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2835 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2836 }
2837
2838 G1CollectedHeap* G1CollectedHeap::heap() {
2839 CollectedHeap* heap = Universe::heap();
2840 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2841 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2842 return (G1CollectedHeap*)heap;
2843 }
2844
2845 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2846 // always_do_update_barrier = false;
2847 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2848 // Fill TLAB's and such
2849 accumulate_statistics_all_tlabs();
2850 ensure_parsability(true);
2851
2852 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2853 }
2854
2855 void G1CollectedHeap::gc_epilogue(bool full) {
2856 // we are at the end of the GC. Total collections has already been increased.
2857 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2858
2859 // FIXME: what is this about?
2860 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2861 // is set.
2862 #if defined(COMPILER2) || INCLUDE_JVMCI
2863 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2864 #endif
2865 // always_do_update_barrier = true;
2866
2867 resize_all_tlabs();
2868 allocation_context_stats().update(full);
2869
2870 // We have just completed a GC. Update the soft reference
2871 // policy with the new heap occupancy
2872 Universe::update_heap_info_at_gc();
2873 }
2874
2875 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2876 uint gc_count_before,
2877 bool* succeeded,
2878 GCCause::Cause gc_cause) {
2879 assert_heap_not_locked_and_not_at_safepoint();
2880 VM_G1IncCollectionPause op(gc_count_before,
2881 word_size,
2882 false, /* should_initiate_conc_mark */
2883 g1_policy()->max_pause_time_ms(),
2884 gc_cause);
2885
2886 op.set_allocation_context(AllocationContext::current());
2887 VMThread::execute(&op);
2888
2889 HeapWord* result = op.result();
2890 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2891 assert(result == NULL || ret_succeeded,
2892 "the result should be NULL if the VM did not succeed");
2893 *succeeded = ret_succeeded;
2894
2895 assert_heap_not_locked();
2896 return result;
2897 }
2898
2899 void
2900 G1CollectedHeap::doConcurrentMark() {
2901 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2902 if (!_cmThread->in_progress()) {
2903 _cmThread->set_started();
2904 CGC_lock->notify();
2905 }
2906 }
2907
2908 size_t G1CollectedHeap::pending_card_num() {
2909 size_t extra_cards = 0;
2910 JavaThread *curr = Threads::first();
2911 while (curr != NULL) {
2912 DirtyCardQueue& dcq = curr->dirty_card_queue();
2913 extra_cards += dcq.size();
2914 curr = curr->next();
2915 }
2916 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2917 size_t buffer_size = dcqs.buffer_size();
2918 size_t buffer_num = dcqs.completed_buffers_num();
2919
2920 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2921 // in bytes - not the number of 'entries'. We need to convert
2922 // into a number of cards.
2923 return (buffer_size * buffer_num + extra_cards) / oopSize;
2924 }
2925
2926 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2927 private:
2928 size_t _total_humongous;
2929 size_t _candidate_humongous;
2930
2931 DirtyCardQueue _dcq;
2932
2933 // We don't nominate objects with many remembered set entries, on
2934 // the assumption that such objects are likely still live.
2935 bool is_remset_small(HeapRegion* region) const {
2936 HeapRegionRemSet* const rset = region->rem_set();
2937 return G1EagerReclaimHumongousObjectsWithStaleRefs
2938 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2939 : rset->is_empty();
2940 }
2941
2942 bool is_typeArray_region(HeapRegion* region) const {
2943 return oop(region->bottom())->is_typeArray();
2944 }
2945
2946 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2947 assert(region->is_starts_humongous(), "Must start a humongous object");
2948
2949 // Candidate selection must satisfy the following constraints
2950 // while concurrent marking is in progress:
2951 //
2952 // * In order to maintain SATB invariants, an object must not be
2953 // reclaimed if it was allocated before the start of marking and
2954 // has not had its references scanned. Such an object must have
2955 // its references (including type metadata) scanned to ensure no
2956 // live objects are missed by the marking process. Objects
2957 // allocated after the start of concurrent marking don't need to
2958 // be scanned.
2959 //
2960 // * An object must not be reclaimed if it is on the concurrent
2961 // mark stack. Objects allocated after the start of concurrent
2962 // marking are never pushed on the mark stack.
2963 //
2964 // Nominating only objects allocated after the start of concurrent
2965 // marking is sufficient to meet both constraints. This may miss
2966 // some objects that satisfy the constraints, but the marking data
2967 // structures don't support efficiently performing the needed
2968 // additional tests or scrubbing of the mark stack.
2969 //
2970 // However, we presently only nominate is_typeArray() objects.
2971 // A humongous object containing references induces remembered
2972 // set entries on other regions. In order to reclaim such an
2973 // object, those remembered sets would need to be cleaned up.
2974 //
2975 // We also treat is_typeArray() objects specially, allowing them
2976 // to be reclaimed even if allocated before the start of
2977 // concurrent mark. For this we rely on mark stack insertion to
2978 // exclude is_typeArray() objects, preventing reclaiming an object
2979 // that is in the mark stack. We also rely on the metadata for
2980 // such objects to be built-in and so ensured to be kept live.
2981 // Frequent allocation and drop of large binary blobs is an
2982 // important use case for eager reclaim, and this special handling
2983 // may reduce needed headroom.
2984
2985 return is_typeArray_region(region) && is_remset_small(region);
2986 }
2987
2988 public:
2989 RegisterHumongousWithInCSetFastTestClosure()
2990 : _total_humongous(0),
2991 _candidate_humongous(0),
2992 _dcq(&JavaThread::dirty_card_queue_set()) {
2993 }
2994
2995 virtual bool doHeapRegion(HeapRegion* r) {
2996 if (!r->is_starts_humongous()) {
2997 return false;
2998 }
2999 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3000
3001 bool is_candidate = humongous_region_is_candidate(g1h, r);
3002 uint rindex = r->hrm_index();
3003 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3004 if (is_candidate) {
3005 _candidate_humongous++;
3006 g1h->register_humongous_region_with_cset(rindex);
3007 // Is_candidate already filters out humongous object with large remembered sets.
3008 // If we have a humongous object with a few remembered sets, we simply flush these
3009 // remembered set entries into the DCQS. That will result in automatic
3010 // re-evaluation of their remembered set entries during the following evacuation
3011 // phase.
3012 if (!r->rem_set()->is_empty()) {
3013 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3014 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3015 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3016 HeapRegionRemSetIterator hrrs(r->rem_set());
3017 size_t card_index;
3018 while (hrrs.has_next(card_index)) {
3019 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3020 // The remembered set might contain references to already freed
3021 // regions. Filter out such entries to avoid failing card table
3022 // verification.
3023 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3024 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3025 *card_ptr = CardTableModRefBS::dirty_card_val();
3026 _dcq.enqueue(card_ptr);
3027 }
3028 }
3029 }
3030 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3031 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3032 hrrs.n_yielded(), r->rem_set()->occupied());
3033 r->rem_set()->clear_locked();
3034 }
3035 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3036 }
3037 _total_humongous++;
3038
3039 return false;
3040 }
3041
3042 size_t total_humongous() const { return _total_humongous; }
3043 size_t candidate_humongous() const { return _candidate_humongous; }
3044
3045 void flush_rem_set_entries() { _dcq.flush(); }
3046 };
3047
3048 void G1CollectedHeap::register_humongous_regions_with_cset() {
3049 if (!G1EagerReclaimHumongousObjects) {
3050 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3051 return;
3052 }
3053 double time = os::elapsed_counter();
3054
3055 // Collect reclaim candidate information and register candidates with cset.
3056 RegisterHumongousWithInCSetFastTestClosure cl;
3057 heap_region_iterate(&cl);
3058
3059 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3060 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3061 cl.total_humongous(),
3062 cl.candidate_humongous());
3063 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3064
3065 // Finally flush all remembered set entries to re-check into the global DCQS.
3066 cl.flush_rem_set_entries();
3067 }
3068
3069 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3070 public:
3071 bool doHeapRegion(HeapRegion* hr) {
3072 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3073 hr->verify_rem_set();
3074 }
3075 return false;
3076 }
3077 };
3078
3079 #ifdef ASSERT
3080 class VerifyCSetClosure: public HeapRegionClosure {
3081 public:
3082 bool doHeapRegion(HeapRegion* hr) {
3083 // Here we check that the CSet region's RSet is ready for parallel
3084 // iteration. The fields that we'll verify are only manipulated
3085 // when the region is part of a CSet and is collected. Afterwards,
3086 // we reset these fields when we clear the region's RSet (when the
3087 // region is freed) so they are ready when the region is
3088 // re-allocated. The only exception to this is if there's an
3089 // evacuation failure and instead of freeing the region we leave
3090 // it in the heap. In that case, we reset these fields during
3091 // evacuation failure handling.
3092 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3093
3094 // Here's a good place to add any other checks we'd like to
3095 // perform on CSet regions.
3096 return false;
3097 }
3098 };
3099 #endif // ASSERT
3100
3101 uint G1CollectedHeap::num_task_queues() const {
3102 return _task_queues->size();
3103 }
3104
3105 #if TASKQUEUE_STATS
3106 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3107 st->print_raw_cr("GC Task Stats");
3108 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3109 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3110 }
3111
3112 void G1CollectedHeap::print_taskqueue_stats() const {
3113 if (!log_is_enabled(Trace, gc, task, stats)) {
3114 return;
3115 }
3116 Log(gc, task, stats) log;
3117 ResourceMark rm;
3118 outputStream* st = log.trace_stream();
3119
3120 print_taskqueue_stats_hdr(st);
3121
3122 TaskQueueStats totals;
3123 const uint n = num_task_queues();
3124 for (uint i = 0; i < n; ++i) {
3125 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3126 totals += task_queue(i)->stats;
3127 }
3128 st->print_raw("tot "); totals.print(st); st->cr();
3129
3130 DEBUG_ONLY(totals.verify());
3131 }
3132
3133 void G1CollectedHeap::reset_taskqueue_stats() {
3134 const uint n = num_task_queues();
3135 for (uint i = 0; i < n; ++i) {
3136 task_queue(i)->stats.reset();
3137 }
3138 }
3139 #endif // TASKQUEUE_STATS
3140
3141 void G1CollectedHeap::wait_for_root_region_scanning() {
3142 double scan_wait_start = os::elapsedTime();
3143 // We have to wait until the CM threads finish scanning the
3144 // root regions as it's the only way to ensure that all the
3145 // objects on them have been correctly scanned before we start
3146 // moving them during the GC.
3147 bool waited = _cm->root_regions()->wait_until_scan_finished();
3148 double wait_time_ms = 0.0;
3149 if (waited) {
3150 double scan_wait_end = os::elapsedTime();
3151 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3152 }
3153 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3154 }
3155
3156 bool
3157 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3158 assert_at_safepoint(true /* should_be_vm_thread */);
3159 guarantee(!is_gc_active(), "collection is not reentrant");
3160
3161 if (GCLocker::check_active_before_gc()) {
3162 return false;
3163 }
3164
3165 _gc_timer_stw->register_gc_start();
3166
3167 GCIdMark gc_id_mark;
3168 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3169
3170 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3171 ResourceMark rm;
3172
3173 wait_for_root_region_scanning();
3174
3175 print_heap_before_gc();
3176 print_heap_regions();
3177 trace_heap_before_gc(_gc_tracer_stw);
3178
3179 _verifier->verify_region_sets_optional();
3180 _verifier->verify_dirty_young_regions();
3181
3182 // We should not be doing initial mark unless the conc mark thread is running
3183 if (!_cmThread->should_terminate()) {
3184 // This call will decide whether this pause is an initial-mark
3185 // pause. If it is, during_initial_mark_pause() will return true
3186 // for the duration of this pause.
3187 g1_policy()->decide_on_conc_mark_initiation();
3188 }
3189
3190 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3191 assert(!collector_state()->during_initial_mark_pause() ||
3192 collector_state()->gcs_are_young(), "sanity");
3193
3194 // We also do not allow mixed GCs during marking.
3195 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3196
3197 // Record whether this pause is an initial mark. When the current
3198 // thread has completed its logging output and it's safe to signal
3199 // the CM thread, the flag's value in the policy has been reset.
3200 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3201
3202 // Inner scope for scope based logging, timers, and stats collection
3203 {
3204 EvacuationInfo evacuation_info;
3205
3206 if (collector_state()->during_initial_mark_pause()) {
3207 // We are about to start a marking cycle, so we increment the
3208 // full collection counter.
3209 increment_old_marking_cycles_started();
3210 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3211 }
3212
3213 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3214
3215 GCTraceCPUTime tcpu;
3216
3217 FormatBuffer<> gc_string("Pause ");
3218 if (collector_state()->during_initial_mark_pause()) {
3219 gc_string.append("Initial Mark");
3220 } else if (collector_state()->gcs_are_young()) {
3221 gc_string.append("Young");
3222 } else {
3223 gc_string.append("Mixed");
3224 }
3225 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3226
3227 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3228 workers()->active_workers(),
3229 Threads::number_of_non_daemon_threads());
3230 workers()->set_active_workers(active_workers);
3231
3232 g1_policy()->note_gc_start();
3233
3234 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3235 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3236
3237 // If the secondary_free_list is not empty, append it to the
3238 // free_list. No need to wait for the cleanup operation to finish;
3239 // the region allocation code will check the secondary_free_list
3240 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3241 // set, skip this step so that the region allocation code has to
3242 // get entries from the secondary_free_list.
3243 if (!G1StressConcRegionFreeing) {
3244 append_secondary_free_list_if_not_empty_with_lock();
3245 }
3246
3247 G1HeapTransition heap_transition(this);
3248 size_t heap_used_bytes_before_gc = used();
3249
3250 assert(check_young_list_well_formed(), "young list should be well formed");
3251
3252 // Don't dynamically change the number of GC threads this early. A value of
3253 // 0 is used to indicate serial work. When parallel work is done,
3254 // it will be set.
3255
3256 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3257 IsGCActiveMark x;
3258
3259 gc_prologue(false);
3260 increment_total_collections(false /* full gc */);
3261 increment_gc_time_stamp();
3262
3263 if (VerifyRememberedSets) {
3264 log_info(gc, verify)("[Verifying RemSets before GC]");
3265 VerifyRegionRemSetClosure v_cl;
3266 heap_region_iterate(&v_cl);
3267 }
3268
3269 _verifier->verify_before_gc();
3270
3271 _verifier->check_bitmaps("GC Start");
3272
3273 #if defined(COMPILER2) || INCLUDE_JVMCI
3274 DerivedPointerTable::clear();
3275 #endif
3276
3277 // Please see comment in g1CollectedHeap.hpp and
3278 // G1CollectedHeap::ref_processing_init() to see how
3279 // reference processing currently works in G1.
3280
3281 // Enable discovery in the STW reference processor
3282 if (g1_policy()->should_process_references()) {
3283 ref_processor_stw()->enable_discovery();
3284 } else {
3285 ref_processor_stw()->disable_discovery();
3286 }
3287
3288 {
3289 // We want to temporarily turn off discovery by the
3290 // CM ref processor, if necessary, and turn it back on
3291 // on again later if we do. Using a scoped
3292 // NoRefDiscovery object will do this.
3293 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3294
3295 // Forget the current alloc region (we might even choose it to be part
3296 // of the collection set!).
3297 _allocator->release_mutator_alloc_region();
3298
3299 // This timing is only used by the ergonomics to handle our pause target.
3300 // It is unclear why this should not include the full pause. We will
3301 // investigate this in CR 7178365.
3302 //
3303 // Preserving the old comment here if that helps the investigation:
3304 //
3305 // The elapsed time induced by the start time below deliberately elides
3306 // the possible verification above.
3307 double sample_start_time_sec = os::elapsedTime();
3308
3309 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3310
3311 if (collector_state()->during_initial_mark_pause()) {
3312 concurrent_mark()->checkpointRootsInitialPre();
3313 }
3314
3315 g1_policy()->finalize_collection_set(target_pause_time_ms);
3316
3317 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3318
3319 // Make sure the remembered sets are up to date. This needs to be
3320 // done before register_humongous_regions_with_cset(), because the
3321 // remembered sets are used there to choose eager reclaim candidates.
3322 // If the remembered sets are not up to date we might miss some
3323 // entries that need to be handled.
3324 g1_rem_set()->cleanupHRRS();
3325
3326 register_humongous_regions_with_cset();
3327
3328 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3329
3330 _cm->note_start_of_gc();
3331 // We call this after finalize_cset() to
3332 // ensure that the CSet has been finalized.
3333 _cm->verify_no_cset_oops();
3334
3335 if (_hr_printer.is_active()) {
3336 HeapRegion* hr = collection_set()->head();
3337 while (hr != NULL) {
3338 _hr_printer.cset(hr);
3339 hr = hr->next_in_collection_set();
3340 }
3341 }
3342
3343 #ifdef ASSERT
3344 VerifyCSetClosure cl;
3345 collection_set_iterate(&cl);
3346 #endif // ASSERT
3347
3348 // Initialize the GC alloc regions.
3349 _allocator->init_gc_alloc_regions(evacuation_info);
3350
3351 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3352 pre_evacuate_collection_set();
3353
3354 // Actually do the work...
3355 evacuate_collection_set(evacuation_info, &per_thread_states);
3356
3357 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3358
3359 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3360 free_collection_set(collection_set()->head(), evacuation_info, surviving_young_words);
3361
3362 eagerly_reclaim_humongous_regions();
3363
3364 collection_set()->clear_head();
3365
3366 record_obj_copy_mem_stats();
3367 _survivor_evac_stats.adjust_desired_plab_sz();
3368 _old_evac_stats.adjust_desired_plab_sz();
3369
3370 // Start a new incremental collection set for the next pause.
3371 collection_set()->start_incremental_building();
3372
3373 clear_cset_fast_test();
3374
3375 // Don't check the whole heap at this point as the
3376 // GC alloc regions from this pause have been tagged
3377 // as survivors and moved on to the survivor list.
3378 // Survivor regions will fail the !is_young() check.
3379 assert(check_young_list_empty(false /* check_heap */),
3380 "young list should be empty");
3381
3382 _young_list->reset_auxilary_lists();
3383
3384 if (evacuation_failed()) {
3385 set_used(recalculate_used());
3386 if (_archive_allocator != NULL) {
3387 _archive_allocator->clear_used();
3388 }
3389 for (uint i = 0; i < ParallelGCThreads; i++) {
3390 if (_evacuation_failed_info_array[i].has_failed()) {
3391 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3392 }
3393 }
3394 } else {
3395 // The "used" of the the collection set have already been subtracted
3396 // when they were freed. Add in the bytes evacuated.
3397 increase_used(g1_policy()->bytes_copied_during_gc());
3398 }
3399
3400 if (collector_state()->during_initial_mark_pause()) {
3401 // We have to do this before we notify the CM threads that
3402 // they can start working to make sure that all the
3403 // appropriate initialization is done on the CM object.
3404 concurrent_mark()->checkpointRootsInitialPost();
3405 collector_state()->set_mark_in_progress(true);
3406 // Note that we don't actually trigger the CM thread at
3407 // this point. We do that later when we're sure that
3408 // the current thread has completed its logging output.
3409 }
3410
3411 allocate_dummy_regions();
3412
3413 _allocator->init_mutator_alloc_region();
3414
3415 {
3416 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3417 if (expand_bytes > 0) {
3418 size_t bytes_before = capacity();
3419 // No need for an ergo logging here,
3420 // expansion_amount() does this when it returns a value > 0.
3421 double expand_ms;
3422 if (!expand(expand_bytes, &expand_ms)) {
3423 // We failed to expand the heap. Cannot do anything about it.
3424 }
3425 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3426 }
3427 }
3428
3429 // We redo the verification but now wrt to the new CSet which
3430 // has just got initialized after the previous CSet was freed.
3431 _cm->verify_no_cset_oops();
3432 _cm->note_end_of_gc();
3433
3434 // This timing is only used by the ergonomics to handle our pause target.
3435 // It is unclear why this should not include the full pause. We will
3436 // investigate this in CR 7178365.
3437 double sample_end_time_sec = os::elapsedTime();
3438 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3439 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3440 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3441
3442 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3443 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3444
3445 MemoryService::track_memory_usage();
3446
3447 // In prepare_for_verify() below we'll need to scan the deferred
3448 // update buffers to bring the RSets up-to-date if
3449 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3450 // the update buffers we'll probably need to scan cards on the
3451 // regions we just allocated to (i.e., the GC alloc
3452 // regions). However, during the last GC we called
3453 // set_saved_mark() on all the GC alloc regions, so card
3454 // scanning might skip the [saved_mark_word()...top()] area of
3455 // those regions (i.e., the area we allocated objects into
3456 // during the last GC). But it shouldn't. Given that
3457 // saved_mark_word() is conditional on whether the GC time stamp
3458 // on the region is current or not, by incrementing the GC time
3459 // stamp here we invalidate all the GC time stamps on all the
3460 // regions and saved_mark_word() will simply return top() for
3461 // all the regions. This is a nicer way of ensuring this rather
3462 // than iterating over the regions and fixing them. In fact, the
3463 // GC time stamp increment here also ensures that
3464 // saved_mark_word() will return top() between pauses, i.e.,
3465 // during concurrent refinement. So we don't need the
3466 // is_gc_active() check to decided which top to use when
3467 // scanning cards (see CR 7039627).
3468 increment_gc_time_stamp();
3469
3470 if (VerifyRememberedSets) {
3471 log_info(gc, verify)("[Verifying RemSets after GC]");
3472 VerifyRegionRemSetClosure v_cl;
3473 heap_region_iterate(&v_cl);
3474 }
3475
3476 _verifier->verify_after_gc();
3477 _verifier->check_bitmaps("GC End");
3478
3479 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3480 ref_processor_stw()->verify_no_references_recorded();
3481
3482 // CM reference discovery will be re-enabled if necessary.
3483 }
3484
3485 #ifdef TRACESPINNING
3486 ParallelTaskTerminator::print_termination_counts();
3487 #endif
3488
3489 gc_epilogue(false);
3490 }
3491
3492 // Print the remainder of the GC log output.
3493 if (evacuation_failed()) {
3494 log_info(gc)("To-space exhausted");
3495 }
3496
3497 g1_policy()->print_phases();
3498 heap_transition.print();
3499
3500 // It is not yet to safe to tell the concurrent mark to
3501 // start as we have some optional output below. We don't want the
3502 // output from the concurrent mark thread interfering with this
3503 // logging output either.
3504
3505 _hrm.verify_optional();
3506 _verifier->verify_region_sets_optional();
3507
3508 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3509 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3510
3511 print_heap_after_gc();
3512 print_heap_regions();
3513 trace_heap_after_gc(_gc_tracer_stw);
3514
3515 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3516 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3517 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3518 // before any GC notifications are raised.
3519 g1mm()->update_sizes();
3520
3521 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3522 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3523 _gc_timer_stw->register_gc_end();
3524 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3525 }
3526 // It should now be safe to tell the concurrent mark thread to start
3527 // without its logging output interfering with the logging output
3528 // that came from the pause.
3529
3530 if (should_start_conc_mark) {
3531 // CAUTION: after the doConcurrentMark() call below,
3532 // the concurrent marking thread(s) could be running
3533 // concurrently with us. Make sure that anything after
3534 // this point does not assume that we are the only GC thread
3535 // running. Note: of course, the actual marking work will
3536 // not start until the safepoint itself is released in
3537 // SuspendibleThreadSet::desynchronize().
3538 doConcurrentMark();
3539 }
3540
3541 return true;
3542 }
3543
3544 void G1CollectedHeap::restore_preserved_marks() {
3545 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3546 workers()->run_task(&rpm_task);
3547 }
3548
3549 void G1CollectedHeap::remove_self_forwarding_pointers() {
3550 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3551 workers()->run_task(&rsfp_task);
3552 }
3553
3554 void G1CollectedHeap::restore_after_evac_failure() {
3555 double remove_self_forwards_start = os::elapsedTime();
3556
3557 remove_self_forwarding_pointers();
3558 restore_preserved_marks();
3559
3560 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3561 }
3562
3563 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3564 if (!_evacuation_failed) {
3565 _evacuation_failed = true;
3566 }
3567
3568 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3569
3570 // We want to call the "for_promotion_failure" version only in the
3571 // case of a promotion failure.
3572 if (m->must_be_preserved_for_promotion_failure(obj)) {
3573 OopAndMarkOop elem(obj, m);
3574 _preserved_objs[worker_id].push(elem);
3575 }
3576 }
3577
3578 bool G1ParEvacuateFollowersClosure::offer_termination() {
3579 G1ParScanThreadState* const pss = par_scan_state();
3580 start_term_time();
3581 const bool res = terminator()->offer_termination();
3582 end_term_time();
3583 return res;
3584 }
3585
3586 void G1ParEvacuateFollowersClosure::do_void() {
3587 G1ParScanThreadState* const pss = par_scan_state();
3588 pss->trim_queue();
3589 do {
3590 pss->steal_and_trim_queue(queues());
3591 } while (!offer_termination());
3592 }
3593
3594 class G1ParTask : public AbstractGangTask {
3595 protected:
3596 G1CollectedHeap* _g1h;
3597 G1ParScanThreadStateSet* _pss;
3598 RefToScanQueueSet* _queues;
3599 G1RootProcessor* _root_processor;
3600 ParallelTaskTerminator _terminator;
3601 uint _n_workers;
3602
3603 public:
3604 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3605 : AbstractGangTask("G1 collection"),
3606 _g1h(g1h),
3607 _pss(per_thread_states),
3608 _queues(task_queues),
3609 _root_processor(root_processor),
3610 _terminator(n_workers, _queues),
3611 _n_workers(n_workers)
3612 {}
3613
3614 void work(uint worker_id) {
3615 if (worker_id >= _n_workers) return; // no work needed this round
3616
3617 double start_sec = os::elapsedTime();
3618 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3619
3620 {
3621 ResourceMark rm;
3622 HandleMark hm;
3623
3624 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3625
3626 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3627 pss->set_ref_processor(rp);
3628
3629 double start_strong_roots_sec = os::elapsedTime();
3630
3631 _root_processor->evacuate_roots(pss->closures(), worker_id);
3632
3633 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3634
3635 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3636 // treating the nmethods visited to act as roots for concurrent marking.
3637 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3638 // objects copied by the current evacuation.
3639 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3640 pss->closures()->weak_codeblobs(),
3641 worker_id);
3642
3643 _pss->add_cards_scanned(worker_id, cards_scanned);
3644
3645 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3646
3647 double term_sec = 0.0;
3648 size_t evac_term_attempts = 0;
3649 {
3650 double start = os::elapsedTime();
3651 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3652 evac.do_void();
3653
3654 evac_term_attempts = evac.term_attempts();
3655 term_sec = evac.term_time();
3656 double elapsed_sec = os::elapsedTime() - start;
3657 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3658 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3659 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3660 }
3661
3662 assert(pss->queue_is_empty(), "should be empty");
3663
3664 if (log_is_enabled(Debug, gc, task, stats)) {
3665 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3666 size_t lab_waste;
3667 size_t lab_undo_waste;
3668 pss->waste(lab_waste, lab_undo_waste);
3669 _g1h->print_termination_stats(worker_id,
3670 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3671 strong_roots_sec * 1000.0, /* strong roots time */
3672 term_sec * 1000.0, /* evac term time */
3673 evac_term_attempts, /* evac term attempts */
3674 lab_waste, /* alloc buffer waste */
3675 lab_undo_waste /* undo waste */
3676 );
3677 }
3678
3679 // Close the inner scope so that the ResourceMark and HandleMark
3680 // destructors are executed here and are included as part of the
3681 // "GC Worker Time".
3682 }
3683 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3684 }
3685 };
3686
3687 void G1CollectedHeap::print_termination_stats_hdr() {
3688 log_debug(gc, task, stats)("GC Termination Stats");
3689 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3690 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3691 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3692 }
3693
3694 void G1CollectedHeap::print_termination_stats(uint worker_id,
3695 double elapsed_ms,
3696 double strong_roots_ms,
3697 double term_ms,
3698 size_t term_attempts,
3699 size_t alloc_buffer_waste,
3700 size_t undo_waste) const {
3701 log_debug(gc, task, stats)
3702 ("%3d %9.2f %9.2f %6.2f "
3703 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3704 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3705 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3706 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3707 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3708 alloc_buffer_waste * HeapWordSize / K,
3709 undo_waste * HeapWordSize / K);
3710 }
3711
3712 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3713 private:
3714 BoolObjectClosure* _is_alive;
3715 int _initial_string_table_size;
3716 int _initial_symbol_table_size;
3717
3718 bool _process_strings;
3719 int _strings_processed;
3720 int _strings_removed;
3721
3722 bool _process_symbols;
3723 int _symbols_processed;
3724 int _symbols_removed;
3725
3726 public:
3727 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3728 AbstractGangTask("String/Symbol Unlinking"),
3729 _is_alive(is_alive),
3730 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3731 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3732
3733 _initial_string_table_size = StringTable::the_table()->table_size();
3734 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3735 if (process_strings) {
3736 StringTable::clear_parallel_claimed_index();
3737 }
3738 if (process_symbols) {
3739 SymbolTable::clear_parallel_claimed_index();
3740 }
3741 }
3742
3743 ~G1StringSymbolTableUnlinkTask() {
3744 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3745 "claim value %d after unlink less than initial string table size %d",
3746 StringTable::parallel_claimed_index(), _initial_string_table_size);
3747 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3748 "claim value %d after unlink less than initial symbol table size %d",
3749 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3750
3751 log_info(gc, stringtable)(
3752 "Cleaned string and symbol table, "
3753 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3754 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3755 strings_processed(), strings_removed(),
3756 symbols_processed(), symbols_removed());
3757 }
3758
3759 void work(uint worker_id) {
3760 int strings_processed = 0;
3761 int strings_removed = 0;
3762 int symbols_processed = 0;
3763 int symbols_removed = 0;
3764 if (_process_strings) {
3765 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3766 Atomic::add(strings_processed, &_strings_processed);
3767 Atomic::add(strings_removed, &_strings_removed);
3768 }
3769 if (_process_symbols) {
3770 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3771 Atomic::add(symbols_processed, &_symbols_processed);
3772 Atomic::add(symbols_removed, &_symbols_removed);
3773 }
3774 }
3775
3776 size_t strings_processed() const { return (size_t)_strings_processed; }
3777 size_t strings_removed() const { return (size_t)_strings_removed; }
3778
3779 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3780 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3781 };
3782
3783 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3784 private:
3785 static Monitor* _lock;
3786
3787 BoolObjectClosure* const _is_alive;
3788 const bool _unloading_occurred;
3789 const uint _num_workers;
3790
3791 // Variables used to claim nmethods.
3792 nmethod* _first_nmethod;
3793 volatile nmethod* _claimed_nmethod;
3794
3795 // The list of nmethods that need to be processed by the second pass.
3796 volatile nmethod* _postponed_list;
3797 volatile uint _num_entered_barrier;
3798
3799 public:
3800 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3801 _is_alive(is_alive),
3802 _unloading_occurred(unloading_occurred),
3803 _num_workers(num_workers),
3804 _first_nmethod(NULL),
3805 _claimed_nmethod(NULL),
3806 _postponed_list(NULL),
3807 _num_entered_barrier(0)
3808 {
3809 nmethod::increase_unloading_clock();
3810 // Get first alive nmethod
3811 NMethodIterator iter = NMethodIterator();
3812 if(iter.next_alive()) {
3813 _first_nmethod = iter.method();
3814 }
3815 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3816 }
3817
3818 ~G1CodeCacheUnloadingTask() {
3819 CodeCache::verify_clean_inline_caches();
3820
3821 CodeCache::set_needs_cache_clean(false);
3822 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3823
3824 CodeCache::verify_icholder_relocations();
3825 }
3826
3827 private:
3828 void add_to_postponed_list(nmethod* nm) {
3829 nmethod* old;
3830 do {
3831 old = (nmethod*)_postponed_list;
3832 nm->set_unloading_next(old);
3833 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3834 }
3835
3836 void clean_nmethod(nmethod* nm) {
3837 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3838
3839 if (postponed) {
3840 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3841 add_to_postponed_list(nm);
3842 }
3843
3844 // Mark that this thread has been cleaned/unloaded.
3845 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3846 nm->set_unloading_clock(nmethod::global_unloading_clock());
3847 }
3848
3849 void clean_nmethod_postponed(nmethod* nm) {
3850 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3851 }
3852
3853 static const int MaxClaimNmethods = 16;
3854
3855 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3856 nmethod* first;
3857 NMethodIterator last;
3858
3859 do {
3860 *num_claimed_nmethods = 0;
3861
3862 first = (nmethod*)_claimed_nmethod;
3863 last = NMethodIterator(first);
3864
3865 if (first != NULL) {
3866
3867 for (int i = 0; i < MaxClaimNmethods; i++) {
3868 if (!last.next_alive()) {
3869 break;
3870 }
3871 claimed_nmethods[i] = last.method();
3872 (*num_claimed_nmethods)++;
3873 }
3874 }
3875
3876 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3877 }
3878
3879 nmethod* claim_postponed_nmethod() {
3880 nmethod* claim;
3881 nmethod* next;
3882
3883 do {
3884 claim = (nmethod*)_postponed_list;
3885 if (claim == NULL) {
3886 return NULL;
3887 }
3888
3889 next = claim->unloading_next();
3890
3891 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3892
3893 return claim;
3894 }
3895
3896 public:
3897 // Mark that we're done with the first pass of nmethod cleaning.
3898 void barrier_mark(uint worker_id) {
3899 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3900 _num_entered_barrier++;
3901 if (_num_entered_barrier == _num_workers) {
3902 ml.notify_all();
3903 }
3904 }
3905
3906 // See if we have to wait for the other workers to
3907 // finish their first-pass nmethod cleaning work.
3908 void barrier_wait(uint worker_id) {
3909 if (_num_entered_barrier < _num_workers) {
3910 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3911 while (_num_entered_barrier < _num_workers) {
3912 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3913 }
3914 }
3915 }
3916
3917 // Cleaning and unloading of nmethods. Some work has to be postponed
3918 // to the second pass, when we know which nmethods survive.
3919 void work_first_pass(uint worker_id) {
3920 // The first nmethods is claimed by the first worker.
3921 if (worker_id == 0 && _first_nmethod != NULL) {
3922 clean_nmethod(_first_nmethod);
3923 _first_nmethod = NULL;
3924 }
3925
3926 int num_claimed_nmethods;
3927 nmethod* claimed_nmethods[MaxClaimNmethods];
3928
3929 while (true) {
3930 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3931
3932 if (num_claimed_nmethods == 0) {
3933 break;
3934 }
3935
3936 for (int i = 0; i < num_claimed_nmethods; i++) {
3937 clean_nmethod(claimed_nmethods[i]);
3938 }
3939 }
3940 }
3941
3942 void work_second_pass(uint worker_id) {
3943 nmethod* nm;
3944 // Take care of postponed nmethods.
3945 while ((nm = claim_postponed_nmethod()) != NULL) {
3946 clean_nmethod_postponed(nm);
3947 }
3948 }
3949 };
3950
3951 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3952
3953 class G1KlassCleaningTask : public StackObj {
3954 BoolObjectClosure* _is_alive;
3955 volatile jint _clean_klass_tree_claimed;
3956 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3957
3958 public:
3959 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3960 _is_alive(is_alive),
3961 _clean_klass_tree_claimed(0),
3962 _klass_iterator() {
3963 }
3964
3965 private:
3966 bool claim_clean_klass_tree_task() {
3967 if (_clean_klass_tree_claimed) {
3968 return false;
3969 }
3970
3971 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3972 }
3973
3974 InstanceKlass* claim_next_klass() {
3975 Klass* klass;
3976 do {
3977 klass =_klass_iterator.next_klass();
3978 } while (klass != NULL && !klass->is_instance_klass());
3979
3980 // this can be null so don't call InstanceKlass::cast
3981 return static_cast<InstanceKlass*>(klass);
3982 }
3983
3984 public:
3985
3986 void clean_klass(InstanceKlass* ik) {
3987 ik->clean_weak_instanceklass_links(_is_alive);
3988 }
3989
3990 void work() {
3991 ResourceMark rm;
3992
3993 // One worker will clean the subklass/sibling klass tree.
3994 if (claim_clean_klass_tree_task()) {
3995 Klass::clean_subklass_tree(_is_alive);
3996 }
3997
3998 // All workers will help cleaning the classes,
3999 InstanceKlass* klass;
4000 while ((klass = claim_next_klass()) != NULL) {
4001 clean_klass(klass);
4002 }
4003 }
4004 };
4005
4006 // To minimize the remark pause times, the tasks below are done in parallel.
4007 class G1ParallelCleaningTask : public AbstractGangTask {
4008 private:
4009 G1StringSymbolTableUnlinkTask _string_symbol_task;
4010 G1CodeCacheUnloadingTask _code_cache_task;
4011 G1KlassCleaningTask _klass_cleaning_task;
4012
4013 public:
4014 // The constructor is run in the VMThread.
4015 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4016 AbstractGangTask("Parallel Cleaning"),
4017 _string_symbol_task(is_alive, process_strings, process_symbols),
4018 _code_cache_task(num_workers, is_alive, unloading_occurred),
4019 _klass_cleaning_task(is_alive) {
4020 }
4021
4022 // The parallel work done by all worker threads.
4023 void work(uint worker_id) {
4024 // Do first pass of code cache cleaning.
4025 _code_cache_task.work_first_pass(worker_id);
4026
4027 // Let the threads mark that the first pass is done.
4028 _code_cache_task.barrier_mark(worker_id);
4029
4030 // Clean the Strings and Symbols.
4031 _string_symbol_task.work(worker_id);
4032
4033 // Wait for all workers to finish the first code cache cleaning pass.
4034 _code_cache_task.barrier_wait(worker_id);
4035
4036 // Do the second code cache cleaning work, which realize on
4037 // the liveness information gathered during the first pass.
4038 _code_cache_task.work_second_pass(worker_id);
4039
4040 // Clean all klasses that were not unloaded.
4041 _klass_cleaning_task.work();
4042 }
4043 };
4044
4045
4046 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4047 bool process_strings,
4048 bool process_symbols,
4049 bool class_unloading_occurred) {
4050 uint n_workers = workers()->active_workers();
4051
4052 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4053 n_workers, class_unloading_occurred);
4054 workers()->run_task(&g1_unlink_task);
4055 }
4056
4057 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4058 bool process_strings, bool process_symbols) {
4059 { // Timing scope
4060 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4061 workers()->run_task(&g1_unlink_task);
4062 }
4063 }
4064
4065 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4066 private:
4067 DirtyCardQueueSet* _queue;
4068 G1CollectedHeap* _g1h;
4069 public:
4070 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4071 _queue(queue), _g1h(g1h) { }
4072
4073 virtual void work(uint worker_id) {
4074 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4075 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4076
4077 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4078 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4079
4080 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4081 }
4082 };
4083
4084 void G1CollectedHeap::redirty_logged_cards() {
4085 double redirty_logged_cards_start = os::elapsedTime();
4086
4087 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4088 dirty_card_queue_set().reset_for_par_iteration();
4089 workers()->run_task(&redirty_task);
4090
4091 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4092 dcq.merge_bufferlists(&dirty_card_queue_set());
4093 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4094
4095 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4096 }
4097
4098 // Weak Reference Processing support
4099
4100 // An always "is_alive" closure that is used to preserve referents.
4101 // If the object is non-null then it's alive. Used in the preservation
4102 // of referent objects that are pointed to by reference objects
4103 // discovered by the CM ref processor.
4104 class G1AlwaysAliveClosure: public BoolObjectClosure {
4105 G1CollectedHeap* _g1;
4106 public:
4107 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4108 bool do_object_b(oop p) {
4109 if (p != NULL) {
4110 return true;
4111 }
4112 return false;
4113 }
4114 };
4115
4116 bool G1STWIsAliveClosure::do_object_b(oop p) {
4117 // An object is reachable if it is outside the collection set,
4118 // or is inside and copied.
4119 return !_g1->is_in_cset(p) || p->is_forwarded();
4120 }
4121
4122 // Non Copying Keep Alive closure
4123 class G1KeepAliveClosure: public OopClosure {
4124 G1CollectedHeap* _g1;
4125 public:
4126 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4127 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4128 void do_oop(oop* p) {
4129 oop obj = *p;
4130 assert(obj != NULL, "the caller should have filtered out NULL values");
4131
4132 const InCSetState cset_state = _g1->in_cset_state(obj);
4133 if (!cset_state.is_in_cset_or_humongous()) {
4134 return;
4135 }
4136 if (cset_state.is_in_cset()) {
4137 assert( obj->is_forwarded(), "invariant" );
4138 *p = obj->forwardee();
4139 } else {
4140 assert(!obj->is_forwarded(), "invariant" );
4141 assert(cset_state.is_humongous(),
4142 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4143 _g1->set_humongous_is_live(obj);
4144 }
4145 }
4146 };
4147
4148 // Copying Keep Alive closure - can be called from both
4149 // serial and parallel code as long as different worker
4150 // threads utilize different G1ParScanThreadState instances
4151 // and different queues.
4152
4153 class G1CopyingKeepAliveClosure: public OopClosure {
4154 G1CollectedHeap* _g1h;
4155 OopClosure* _copy_non_heap_obj_cl;
4156 G1ParScanThreadState* _par_scan_state;
4157
4158 public:
4159 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4160 OopClosure* non_heap_obj_cl,
4161 G1ParScanThreadState* pss):
4162 _g1h(g1h),
4163 _copy_non_heap_obj_cl(non_heap_obj_cl),
4164 _par_scan_state(pss)
4165 {}
4166
4167 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4168 virtual void do_oop( oop* p) { do_oop_work(p); }
4169
4170 template <class T> void do_oop_work(T* p) {
4171 oop obj = oopDesc::load_decode_heap_oop(p);
4172
4173 if (_g1h->is_in_cset_or_humongous(obj)) {
4174 // If the referent object has been forwarded (either copied
4175 // to a new location or to itself in the event of an
4176 // evacuation failure) then we need to update the reference
4177 // field and, if both reference and referent are in the G1
4178 // heap, update the RSet for the referent.
4179 //
4180 // If the referent has not been forwarded then we have to keep
4181 // it alive by policy. Therefore we have copy the referent.
4182 //
4183 // If the reference field is in the G1 heap then we can push
4184 // on the PSS queue. When the queue is drained (after each
4185 // phase of reference processing) the object and it's followers
4186 // will be copied, the reference field set to point to the
4187 // new location, and the RSet updated. Otherwise we need to
4188 // use the the non-heap or metadata closures directly to copy
4189 // the referent object and update the pointer, while avoiding
4190 // updating the RSet.
4191
4192 if (_g1h->is_in_g1_reserved(p)) {
4193 _par_scan_state->push_on_queue(p);
4194 } else {
4195 assert(!Metaspace::contains((const void*)p),
4196 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4197 _copy_non_heap_obj_cl->do_oop(p);
4198 }
4199 }
4200 }
4201 };
4202
4203 // Serial drain queue closure. Called as the 'complete_gc'
4204 // closure for each discovered list in some of the
4205 // reference processing phases.
4206
4207 class G1STWDrainQueueClosure: public VoidClosure {
4208 protected:
4209 G1CollectedHeap* _g1h;
4210 G1ParScanThreadState* _par_scan_state;
4211
4212 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4213
4214 public:
4215 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4216 _g1h(g1h),
4217 _par_scan_state(pss)
4218 { }
4219
4220 void do_void() {
4221 G1ParScanThreadState* const pss = par_scan_state();
4222 pss->trim_queue();
4223 }
4224 };
4225
4226 // Parallel Reference Processing closures
4227
4228 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4229 // processing during G1 evacuation pauses.
4230
4231 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4232 private:
4233 G1CollectedHeap* _g1h;
4234 G1ParScanThreadStateSet* _pss;
4235 RefToScanQueueSet* _queues;
4236 WorkGang* _workers;
4237 uint _active_workers;
4238
4239 public:
4240 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4241 G1ParScanThreadStateSet* per_thread_states,
4242 WorkGang* workers,
4243 RefToScanQueueSet *task_queues,
4244 uint n_workers) :
4245 _g1h(g1h),
4246 _pss(per_thread_states),
4247 _queues(task_queues),
4248 _workers(workers),
4249 _active_workers(n_workers)
4250 {
4251 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4252 }
4253
4254 // Executes the given task using concurrent marking worker threads.
4255 virtual void execute(ProcessTask& task);
4256 virtual void execute(EnqueueTask& task);
4257 };
4258
4259 // Gang task for possibly parallel reference processing
4260
4261 class G1STWRefProcTaskProxy: public AbstractGangTask {
4262 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4263 ProcessTask& _proc_task;
4264 G1CollectedHeap* _g1h;
4265 G1ParScanThreadStateSet* _pss;
4266 RefToScanQueueSet* _task_queues;
4267 ParallelTaskTerminator* _terminator;
4268
4269 public:
4270 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4271 G1CollectedHeap* g1h,
4272 G1ParScanThreadStateSet* per_thread_states,
4273 RefToScanQueueSet *task_queues,
4274 ParallelTaskTerminator* terminator) :
4275 AbstractGangTask("Process reference objects in parallel"),
4276 _proc_task(proc_task),
4277 _g1h(g1h),
4278 _pss(per_thread_states),
4279 _task_queues(task_queues),
4280 _terminator(terminator)
4281 {}
4282
4283 virtual void work(uint worker_id) {
4284 // The reference processing task executed by a single worker.
4285 ResourceMark rm;
4286 HandleMark hm;
4287
4288 G1STWIsAliveClosure is_alive(_g1h);
4289
4290 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4291 pss->set_ref_processor(NULL);
4292
4293 // Keep alive closure.
4294 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4295
4296 // Complete GC closure
4297 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4298
4299 // Call the reference processing task's work routine.
4300 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4301
4302 // Note we cannot assert that the refs array is empty here as not all
4303 // of the processing tasks (specifically phase2 - pp2_work) execute
4304 // the complete_gc closure (which ordinarily would drain the queue) so
4305 // the queue may not be empty.
4306 }
4307 };
4308
4309 // Driver routine for parallel reference processing.
4310 // Creates an instance of the ref processing gang
4311 // task and has the worker threads execute it.
4312 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4313 assert(_workers != NULL, "Need parallel worker threads.");
4314
4315 ParallelTaskTerminator terminator(_active_workers, _queues);
4316 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4317
4318 _workers->run_task(&proc_task_proxy);
4319 }
4320
4321 // Gang task for parallel reference enqueueing.
4322
4323 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4324 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4325 EnqueueTask& _enq_task;
4326
4327 public:
4328 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4329 AbstractGangTask("Enqueue reference objects in parallel"),
4330 _enq_task(enq_task)
4331 { }
4332
4333 virtual void work(uint worker_id) {
4334 _enq_task.work(worker_id);
4335 }
4336 };
4337
4338 // Driver routine for parallel reference enqueueing.
4339 // Creates an instance of the ref enqueueing gang
4340 // task and has the worker threads execute it.
4341
4342 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4343 assert(_workers != NULL, "Need parallel worker threads.");
4344
4345 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4346
4347 _workers->run_task(&enq_task_proxy);
4348 }
4349
4350 // End of weak reference support closures
4351
4352 // Abstract task used to preserve (i.e. copy) any referent objects
4353 // that are in the collection set and are pointed to by reference
4354 // objects discovered by the CM ref processor.
4355
4356 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4357 protected:
4358 G1CollectedHeap* _g1h;
4359 G1ParScanThreadStateSet* _pss;
4360 RefToScanQueueSet* _queues;
4361 ParallelTaskTerminator _terminator;
4362 uint _n_workers;
4363
4364 public:
4365 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4366 AbstractGangTask("ParPreserveCMReferents"),
4367 _g1h(g1h),
4368 _pss(per_thread_states),
4369 _queues(task_queues),
4370 _terminator(workers, _queues),
4371 _n_workers(workers)
4372 {
4373 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4374 }
4375
4376 void work(uint worker_id) {
4377 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4378
4379 ResourceMark rm;
4380 HandleMark hm;
4381
4382 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4383 pss->set_ref_processor(NULL);
4384 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4385
4386 // Is alive closure
4387 G1AlwaysAliveClosure always_alive(_g1h);
4388
4389 // Copying keep alive closure. Applied to referent objects that need
4390 // to be copied.
4391 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4392
4393 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4394
4395 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4396 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4397
4398 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4399 // So this must be true - but assert just in case someone decides to
4400 // change the worker ids.
4401 assert(worker_id < limit, "sanity");
4402 assert(!rp->discovery_is_atomic(), "check this code");
4403
4404 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4405 for (uint idx = worker_id; idx < limit; idx += stride) {
4406 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4407
4408 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4409 while (iter.has_next()) {
4410 // Since discovery is not atomic for the CM ref processor, we
4411 // can see some null referent objects.
4412 iter.load_ptrs(DEBUG_ONLY(true));
4413 oop ref = iter.obj();
4414
4415 // This will filter nulls.
4416 if (iter.is_referent_alive()) {
4417 iter.make_referent_alive();
4418 }
4419 iter.move_to_next();
4420 }
4421 }
4422
4423 // Drain the queue - which may cause stealing
4424 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4425 drain_queue.do_void();
4426 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4427 assert(pss->queue_is_empty(), "should be");
4428 }
4429 };
4430
4431 void G1CollectedHeap::process_weak_jni_handles() {
4432 double ref_proc_start = os::elapsedTime();
4433
4434 G1STWIsAliveClosure is_alive(this);
4435 G1KeepAliveClosure keep_alive(this);
4436 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4437
4438 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4439 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4440 }
4441
4442 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4443 double preserve_cm_referents_start = os::elapsedTime();
4444 // Any reference objects, in the collection set, that were 'discovered'
4445 // by the CM ref processor should have already been copied (either by
4446 // applying the external root copy closure to the discovered lists, or
4447 // by following an RSet entry).
4448 //
4449 // But some of the referents, that are in the collection set, that these
4450 // reference objects point to may not have been copied: the STW ref
4451 // processor would have seen that the reference object had already
4452 // been 'discovered' and would have skipped discovering the reference,
4453 // but would not have treated the reference object as a regular oop.
4454 // As a result the copy closure would not have been applied to the
4455 // referent object.
4456 //
4457 // We need to explicitly copy these referent objects - the references
4458 // will be processed at the end of remarking.
4459 //
4460 // We also need to do this copying before we process the reference
4461 // objects discovered by the STW ref processor in case one of these
4462 // referents points to another object which is also referenced by an
4463 // object discovered by the STW ref processor.
4464
4465 uint no_of_gc_workers = workers()->active_workers();
4466
4467 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4468 per_thread_states,
4469 no_of_gc_workers,
4470 _task_queues);
4471 workers()->run_task(&keep_cm_referents);
4472
4473 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
4474 }
4475
4476 // Weak Reference processing during an evacuation pause (part 1).
4477 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4478 double ref_proc_start = os::elapsedTime();
4479
4480 ReferenceProcessor* rp = _ref_processor_stw;
4481 assert(rp->discovery_enabled(), "should have been enabled");
4482
4483 // Closure to test whether a referent is alive.
4484 G1STWIsAliveClosure is_alive(this);
4485
4486 // Even when parallel reference processing is enabled, the processing
4487 // of JNI refs is serial and performed serially by the current thread
4488 // rather than by a worker. The following PSS will be used for processing
4489 // JNI refs.
4490
4491 // Use only a single queue for this PSS.
4492 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4493 pss->set_ref_processor(NULL);
4494 assert(pss->queue_is_empty(), "pre-condition");
4495
4496 // Keep alive closure.
4497 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4498
4499 // Serial Complete GC closure
4500 G1STWDrainQueueClosure drain_queue(this, pss);
4501
4502 // Setup the soft refs policy...
4503 rp->setup_policy(false);
4504
4505 ReferenceProcessorStats stats;
4506 if (!rp->processing_is_mt()) {
4507 // Serial reference processing...
4508 stats = rp->process_discovered_references(&is_alive,
4509 &keep_alive,
4510 &drain_queue,
4511 NULL,
4512 _gc_timer_stw);
4513 } else {
4514 uint no_of_gc_workers = workers()->active_workers();
4515
4516 // Parallel reference processing
4517 assert(no_of_gc_workers <= rp->max_num_q(),
4518 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4519 no_of_gc_workers, rp->max_num_q());
4520
4521 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4522 stats = rp->process_discovered_references(&is_alive,
4523 &keep_alive,
4524 &drain_queue,
4525 &par_task_executor,
4526 _gc_timer_stw);
4527 }
4528
4529 _gc_tracer_stw->report_gc_reference_stats(stats);
4530
4531 // We have completed copying any necessary live referent objects.
4532 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4533
4534 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4535 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4536 }
4537
4538 // Weak Reference processing during an evacuation pause (part 2).
4539 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4540 double ref_enq_start = os::elapsedTime();
4541
4542 ReferenceProcessor* rp = _ref_processor_stw;
4543 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4544
4545 // Now enqueue any remaining on the discovered lists on to
4546 // the pending list.
4547 if (!rp->processing_is_mt()) {
4548 // Serial reference processing...
4549 rp->enqueue_discovered_references();
4550 } else {
4551 // Parallel reference enqueueing
4552
4553 uint n_workers = workers()->active_workers();
4554
4555 assert(n_workers <= rp->max_num_q(),
4556 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4557 n_workers, rp->max_num_q());
4558
4559 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4560 rp->enqueue_discovered_references(&par_task_executor);
4561 }
4562
4563 rp->verify_no_references_recorded();
4564 assert(!rp->discovery_enabled(), "should have been disabled");
4565
4566 // FIXME
4567 // CM's reference processing also cleans up the string and symbol tables.
4568 // Should we do that here also? We could, but it is a serial operation
4569 // and could significantly increase the pause time.
4570
4571 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4572 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4573 }
4574
4575 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4576 double merge_pss_time_start = os::elapsedTime();
4577 per_thread_states->flush();
4578 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4579 }
4580
4581 void G1CollectedHeap::pre_evacuate_collection_set() {
4582 _expand_heap_after_alloc_failure = true;
4583 _evacuation_failed = false;
4584
4585 // Disable the hot card cache.
4586 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4587 hot_card_cache->reset_hot_cache_claimed_index();
4588 hot_card_cache->set_use_cache(false);
4589
4590 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4591 }
4592
4593 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4594 // Should G1EvacuationFailureALot be in effect for this GC?
4595 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4596
4597 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4598 double start_par_time_sec = os::elapsedTime();
4599 double end_par_time_sec;
4600
4601 {
4602 const uint n_workers = workers()->active_workers();
4603 G1RootProcessor root_processor(this, n_workers);
4604 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4605 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4606 if (collector_state()->during_initial_mark_pause()) {
4607 ClassLoaderDataGraph::clear_claimed_marks();
4608 }
4609
4610 print_termination_stats_hdr();
4611
4612 workers()->run_task(&g1_par_task);
4613 end_par_time_sec = os::elapsedTime();
4614
4615 // Closing the inner scope will execute the destructor
4616 // for the G1RootProcessor object. We record the current
4617 // elapsed time before closing the scope so that time
4618 // taken for the destructor is NOT included in the
4619 // reported parallel time.
4620 }
4621
4622 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4623
4624 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4625 phase_times->record_par_time(par_time_ms);
4626
4627 double code_root_fixup_time_ms =
4628 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4629 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4630 }
4631
4632 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4633 // Process any discovered reference objects - we have
4634 // to do this _before_ we retire the GC alloc regions
4635 // as we may have to copy some 'reachable' referent
4636 // objects (and their reachable sub-graphs) that were
4637 // not copied during the pause.
4638 if (g1_policy()->should_process_references()) {
4639 preserve_cm_referents(per_thread_states);
4640 process_discovered_references(per_thread_states);
4641 } else {
4642 ref_processor_stw()->verify_no_references_recorded();
4643 process_weak_jni_handles();
4644 }
4645
4646 if (G1StringDedup::is_enabled()) {
4647 double fixup_start = os::elapsedTime();
4648
4649 G1STWIsAliveClosure is_alive(this);
4650 G1KeepAliveClosure keep_alive(this);
4651 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4652
4653 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4654 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4655 }
4656
4657 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4658
4659 if (evacuation_failed()) {
4660 restore_after_evac_failure();
4661
4662 // Reset the G1EvacuationFailureALot counters and flags
4663 // Note: the values are reset only when an actual
4664 // evacuation failure occurs.
4665 NOT_PRODUCT(reset_evacuation_should_fail();)
4666 }
4667
4668 // Enqueue any remaining references remaining on the STW
4669 // reference processor's discovered lists. We need to do
4670 // this after the card table is cleaned (and verified) as
4671 // the act of enqueueing entries on to the pending list
4672 // will log these updates (and dirty their associated
4673 // cards). We need these updates logged to update any
4674 // RSets.
4675 if (g1_policy()->should_process_references()) {
4676 enqueue_discovered_references(per_thread_states);
4677 } else {
4678 g1_policy()->phase_times()->record_ref_enq_time(0);
4679 }
4680
4681 _allocator->release_gc_alloc_regions(evacuation_info);
4682
4683 merge_per_thread_state_info(per_thread_states);
4684
4685 // Reset and re-enable the hot card cache.
4686 // Note the counts for the cards in the regions in the
4687 // collection set are reset when the collection set is freed.
4688 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4689 hot_card_cache->reset_hot_cache();
4690 hot_card_cache->set_use_cache(true);
4691
4692 purge_code_root_memory();
4693
4694 redirty_logged_cards();
4695 #if defined(COMPILER2) || INCLUDE_JVMCI
4696 DerivedPointerTable::update_pointers();
4697 #endif
4698 }
4699
4700 void G1CollectedHeap::record_obj_copy_mem_stats() {
4701 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4702
4703 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4704 create_g1_evac_summary(&_old_evac_stats));
4705 }
4706
4707 void G1CollectedHeap::free_region(HeapRegion* hr,
4708 FreeRegionList* free_list,
4709 bool par,
4710 bool locked) {
4711 assert(!hr->is_free(), "the region should not be free");
4712 assert(!hr->is_empty(), "the region should not be empty");
4713 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4714 assert(free_list != NULL, "pre-condition");
4715
4716 if (G1VerifyBitmaps) {
4717 MemRegion mr(hr->bottom(), hr->end());
4718 concurrent_mark()->clearRangePrevBitmap(mr);
4719 }
4720
4721 // Clear the card counts for this region.
4722 // Note: we only need to do this if the region is not young
4723 // (since we don't refine cards in young regions).
4724 if (!hr->is_young()) {
4725 _cg1r->hot_card_cache()->reset_card_counts(hr);
4726 }
4727 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4728 free_list->add_ordered(hr);
4729 }
4730
4731 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4732 FreeRegionList* free_list,
4733 bool par) {
4734 assert(hr->is_humongous(), "this is only for humongous regions");
4735 assert(free_list != NULL, "pre-condition");
4736 hr->clear_humongous();
4737 free_region(hr, free_list, par);
4738 }
4739
4740 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4741 const uint humongous_regions_removed) {
4742 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4743 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4744 _old_set.bulk_remove(old_regions_removed);
4745 _humongous_set.bulk_remove(humongous_regions_removed);
4746 }
4747
4748 }
4749
4750 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4751 assert(list != NULL, "list can't be null");
4752 if (!list->is_empty()) {
4753 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4754 _hrm.insert_list_into_free_list(list);
4755 }
4756 }
4757
4758 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4759 decrease_used(bytes);
4760 }
4761
4762 class G1ParCleanupCTTask : public AbstractGangTask {
4763 G1SATBCardTableModRefBS* _ct_bs;
4764 G1CollectedHeap* _g1h;
4765 HeapRegion* volatile _su_head;
4766 public:
4767 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4768 G1CollectedHeap* g1h) :
4769 AbstractGangTask("G1 Par Cleanup CT Task"),
4770 _ct_bs(ct_bs), _g1h(g1h) { }
4771
4772 void work(uint worker_id) {
4773 HeapRegion* r;
4774 while (r = _g1h->pop_dirty_cards_region()) {
4775 clear_cards(r);
4776 }
4777 }
4778
4779 void clear_cards(HeapRegion* r) {
4780 // Cards of the survivors should have already been dirtied.
4781 if (!r->is_survivor()) {
4782 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4783 }
4784 }
4785 };
4786
4787 class G1ParScrubRemSetTask: public AbstractGangTask {
4788 protected:
4789 G1RemSet* _g1rs;
4790 BitMap* _region_bm;
4791 BitMap* _card_bm;
4792 HeapRegionClaimer _hrclaimer;
4793
4794 public:
4795 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4796 AbstractGangTask("G1 ScrubRS"),
4797 _g1rs(g1_rs),
4798 _region_bm(region_bm),
4799 _card_bm(card_bm),
4800 _hrclaimer(num_workers) {
4801 }
4802
4803 void work(uint worker_id) {
4804 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4805 }
4806 };
4807
4808 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4809 uint num_workers = workers()->active_workers();
4810 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4811 workers()->run_task(&g1_par_scrub_rs_task);
4812 }
4813
4814 void G1CollectedHeap::cleanUpCardTable() {
4815 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4816 double start = os::elapsedTime();
4817
4818 {
4819 // Iterate over the dirty cards region list.
4820 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4821
4822 workers()->run_task(&cleanup_task);
4823 #ifndef PRODUCT
4824 _verifier->verify_card_table_cleanup();
4825 #endif
4826 }
4827
4828 double elapsed = os::elapsedTime() - start;
4829 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4830 }
4831
4832 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4833 size_t pre_used = 0;
4834 FreeRegionList local_free_list("Local List for CSet Freeing");
4835
4836 double young_time_ms = 0.0;
4837 double non_young_time_ms = 0.0;
4838
4839 // Since the collection set is a superset of the the young list,
4840 // all we need to do to clear the young list is clear its
4841 // head and length, and unlink any young regions in the code below
4842 _young_list->clear();
4843
4844 G1CollectorPolicy* policy = g1_policy();
4845
4846 double start_sec = os::elapsedTime();
4847 bool non_young = true;
4848
4849 HeapRegion* cur = cs_head;
4850 int age_bound = -1;
4851 size_t rs_lengths = 0;
4852
4853 while (cur != NULL) {
4854 assert(!is_on_master_free_list(cur), "sanity");
4855 if (non_young) {
4856 if (cur->is_young()) {
4857 double end_sec = os::elapsedTime();
4858 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4859 non_young_time_ms += elapsed_ms;
4860
4861 start_sec = os::elapsedTime();
4862 non_young = false;
4863 }
4864 } else {
4865 if (!cur->is_young()) {
4866 double end_sec = os::elapsedTime();
4867 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4868 young_time_ms += elapsed_ms;
4869
4870 start_sec = os::elapsedTime();
4871 non_young = true;
4872 }
4873 }
4874
4875 rs_lengths += cur->rem_set()->occupied_locked();
4876
4877 HeapRegion* next = cur->next_in_collection_set();
4878 assert(cur->in_collection_set(), "bad CS");
4879 cur->set_next_in_collection_set(NULL);
4880 clear_in_cset(cur);
4881
4882 if (cur->is_young()) {
4883 int index = cur->young_index_in_cset();
4884 assert(index != -1, "invariant");
4885 assert((uint) index < collection_set()->young_region_length(), "invariant");
4886 size_t words_survived = surviving_young_words[index];
4887 cur->record_surv_words_in_group(words_survived);
4888
4889 // At this point the we have 'popped' cur from the collection set
4890 // (linked via next_in_collection_set()) but it is still in the
4891 // young list (linked via next_young_region()). Clear the
4892 // _next_young_region field.
4893 cur->set_next_young_region(NULL);
4894 } else {
4895 int index = cur->young_index_in_cset();
4896 assert(index == -1, "invariant");
4897 }
4898
4899 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4900 (!cur->is_young() && cur->young_index_in_cset() == -1),
4901 "invariant" );
4902
4903 if (!cur->evacuation_failed()) {
4904 MemRegion used_mr = cur->used_region();
4905
4906 // And the region is empty.
4907 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4908 pre_used += cur->used();
4909 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4910 } else {
4911 cur->uninstall_surv_rate_group();
4912 if (cur->is_young()) {
4913 cur->set_young_index_in_cset(-1);
4914 }
4915 cur->set_evacuation_failed(false);
4916 // When moving a young gen region to old gen, we "allocate" that whole region
4917 // there. This is in addition to any already evacuated objects. Notify the
4918 // policy about that.
4919 // Old gen regions do not cause an additional allocation: both the objects
4920 // still in the region and the ones already moved are accounted for elsewhere.
4921 if (cur->is_young()) {
4922 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4923 }
4924 // The region is now considered to be old.
4925 cur->set_old();
4926 // Do some allocation statistics accounting. Regions that failed evacuation
4927 // are always made old, so there is no need to update anything in the young
4928 // gen statistics, but we need to update old gen statistics.
4929 size_t used_words = cur->marked_bytes() / HeapWordSize;
4930 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4931 _old_set.add(cur);
4932 evacuation_info.increment_collectionset_used_after(cur->used());
4933 }
4934 cur = next;
4935 }
4936
4937 evacuation_info.set_regions_freed(local_free_list.length());
4938 policy->record_max_rs_lengths(rs_lengths);
4939 policy->cset_regions_freed();
4940
4941 double end_sec = os::elapsedTime();
4942 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4943
4944 if (non_young) {
4945 non_young_time_ms += elapsed_ms;
4946 } else {
4947 young_time_ms += elapsed_ms;
4948 }
4949
4950 prepend_to_freelist(&local_free_list);
4951 decrement_summary_bytes(pre_used);
4952 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4953 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4954 }
4955
4956 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4957 private:
4958 FreeRegionList* _free_region_list;
4959 HeapRegionSet* _proxy_set;
4960 uint _humongous_regions_removed;
4961 size_t _freed_bytes;
4962 public:
4963
4964 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4965 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4966 }
4967
4968 virtual bool doHeapRegion(HeapRegion* r) {
4969 if (!r->is_starts_humongous()) {
4970 return false;
4971 }
4972
4973 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4974
4975 oop obj = (oop)r->bottom();
4976 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4977
4978 // The following checks whether the humongous object is live are sufficient.
4979 // The main additional check (in addition to having a reference from the roots
4980 // or the young gen) is whether the humongous object has a remembered set entry.
4981 //
4982 // A humongous object cannot be live if there is no remembered set for it
4983 // because:
4984 // - there can be no references from within humongous starts regions referencing
4985 // the object because we never allocate other objects into them.
4986 // (I.e. there are no intra-region references that may be missed by the
4987 // remembered set)
4988 // - as soon there is a remembered set entry to the humongous starts region
4989 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4990 // until the end of a concurrent mark.
4991 //
4992 // It is not required to check whether the object has been found dead by marking
4993 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4994 // all objects allocated during that time are considered live.
4995 // SATB marking is even more conservative than the remembered set.
4996 // So if at this point in the collection there is no remembered set entry,
4997 // nobody has a reference to it.
4998 // At the start of collection we flush all refinement logs, and remembered sets
4999 // are completely up-to-date wrt to references to the humongous object.
5000 //
5001 // Other implementation considerations:
5002 // - never consider object arrays at this time because they would pose
5003 // considerable effort for cleaning up the the remembered sets. This is
5004 // required because stale remembered sets might reference locations that
5005 // are currently allocated into.
5006 uint region_idx = r->hrm_index();
5007 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5008 !r->rem_set()->is_empty()) {
5009 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",
5010 region_idx,
5011 (size_t)obj->size() * HeapWordSize,
5012 p2i(r->bottom()),
5013 r->rem_set()->occupied(),
5014 r->rem_set()->strong_code_roots_list_length(),
5015 next_bitmap->isMarked(r->bottom()),
5016 g1h->is_humongous_reclaim_candidate(region_idx),
5017 obj->is_typeArray()
5018 );
5019 return false;
5020 }
5021
5022 guarantee(obj->is_typeArray(),
5023 "Only eagerly reclaiming type arrays is supported, but the object "
5024 PTR_FORMAT " is not.", p2i(r->bottom()));
5025
5026 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",
5027 region_idx,
5028 (size_t)obj->size() * HeapWordSize,
5029 p2i(r->bottom()),
5030 r->rem_set()->occupied(),
5031 r->rem_set()->strong_code_roots_list_length(),
5032 next_bitmap->isMarked(r->bottom()),
5033 g1h->is_humongous_reclaim_candidate(region_idx),
5034 obj->is_typeArray()
5035 );
5036
5037 // Need to clear mark bit of the humongous object if already set.
5038 if (next_bitmap->isMarked(r->bottom())) {
5039 next_bitmap->clear(r->bottom());
5040 }
5041 do {
5042 HeapRegion* next = g1h->next_region_in_humongous(r);
5043 _freed_bytes += r->used();
5044 r->set_containing_set(NULL);
5045 _humongous_regions_removed++;
5046 g1h->free_humongous_region(r, _free_region_list, false);
5047 r = next;
5048 } while (r != NULL);
5049
5050 return false;
5051 }
5052
5053 uint humongous_free_count() {
5054 return _humongous_regions_removed;
5055 }
5056
5057 size_t bytes_freed() const {
5058 return _freed_bytes;
5059 }
5060 };
5061
5062 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5063 assert_at_safepoint(true);
5064
5065 if (!G1EagerReclaimHumongousObjects ||
5066 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5067 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5068 return;
5069 }
5070
5071 double start_time = os::elapsedTime();
5072
5073 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5074
5075 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5076 heap_region_iterate(&cl);
5077
5078 remove_from_old_sets(0, cl.humongous_free_count());
5079
5080 G1HRPrinter* hrp = hr_printer();
5081 if (hrp->is_active()) {
5082 FreeRegionListIterator iter(&local_cleanup_list);
5083 while (iter.more_available()) {
5084 HeapRegion* hr = iter.get_next();
5085 hrp->cleanup(hr);
5086 }
5087 }
5088
5089 prepend_to_freelist(&local_cleanup_list);
5090 decrement_summary_bytes(cl.bytes_freed());
5091
5092 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5093 cl.humongous_free_count());
5094 }
5095
5096 // This routine is similar to the above but does not record
5097 // any policy statistics or update free lists; we are abandoning
5098 // the current incremental collection set in preparation of a
5099 // full collection. After the full GC we will start to build up
5100 // the incremental collection set again.
5101 // This is only called when we're doing a full collection
5102 // and is immediately followed by the tearing down of the young list.
5103
5104 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5105 HeapRegion* cur = cs_head;
5106
5107 while (cur != NULL) {
5108 HeapRegion* next = cur->next_in_collection_set();
5109 assert(cur->in_collection_set(), "bad CS");
5110 cur->set_next_in_collection_set(NULL);
5111 clear_in_cset(cur);
5112 cur->set_young_index_in_cset(-1);
5113 cur = next;
5114 }
5115 }
5116
5117 void G1CollectedHeap::set_free_regions_coming() {
5118 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5119
5120 assert(!free_regions_coming(), "pre-condition");
5121 _free_regions_coming = true;
5122 }
5123
5124 void G1CollectedHeap::reset_free_regions_coming() {
5125 assert(free_regions_coming(), "pre-condition");
5126
5127 {
5128 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5129 _free_regions_coming = false;
5130 SecondaryFreeList_lock->notify_all();
5131 }
5132
5133 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5134 }
5135
5136 void G1CollectedHeap::wait_while_free_regions_coming() {
5137 // Most of the time we won't have to wait, so let's do a quick test
5138 // first before we take the lock.
5139 if (!free_regions_coming()) {
5140 return;
5141 }
5142
5143 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5144
5145 {
5146 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5147 while (free_regions_coming()) {
5148 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5149 }
5150 }
5151
5152 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5153 }
5154
5155 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5156 return _allocator->is_retained_old_region(hr);
5157 }
5158
5159 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5160 _young_list->push_region(hr);
5161 }
5162
5163 class NoYoungRegionsClosure: public HeapRegionClosure {
5164 private:
5165 bool _success;
5166 public:
5167 NoYoungRegionsClosure() : _success(true) { }
5168 bool doHeapRegion(HeapRegion* r) {
5169 if (r->is_young()) {
5170 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5171 p2i(r->bottom()), p2i(r->end()));
5172 _success = false;
5173 }
5174 return false;
5175 }
5176 bool success() { return _success; }
5177 };
5178
5179 bool G1CollectedHeap::check_young_list_empty(bool check_heap) {
5180 bool ret = _young_list->check_list_empty();
5181
5182 if (check_heap) {
5183 NoYoungRegionsClosure closure;
5184 heap_region_iterate(&closure);
5185 ret = ret && closure.success();
5186 }
5187
5188 return ret;
5189 }
5190
5191 class TearDownRegionSetsClosure : public HeapRegionClosure {
5192 private:
5193 HeapRegionSet *_old_set;
5194
5195 public:
5196 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5197
5198 bool doHeapRegion(HeapRegion* r) {
5199 if (r->is_old()) {
5200 _old_set->remove(r);
5201 } else {
5202 // We ignore free regions, we'll empty the free list afterwards.
5203 // We ignore young regions, we'll empty the young list afterwards.
5204 // We ignore humongous regions, we're not tearing down the
5205 // humongous regions set.
5206 assert(r->is_free() || r->is_young() || r->is_humongous(),
5207 "it cannot be another type");
5208 }
5209 return false;
5210 }
5211
5212 ~TearDownRegionSetsClosure() {
5213 assert(_old_set->is_empty(), "post-condition");
5214 }
5215 };
5216
5217 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5218 assert_at_safepoint(true /* should_be_vm_thread */);
5219
5220 if (!free_list_only) {
5221 TearDownRegionSetsClosure cl(&_old_set);
5222 heap_region_iterate(&cl);
5223
5224 // Note that emptying the _young_list is postponed and instead done as
5225 // the first step when rebuilding the regions sets again. The reason for
5226 // this is that during a full GC string deduplication needs to know if
5227 // a collected region was young or old when the full GC was initiated.
5228 }
5229 _hrm.remove_all_free_regions();
5230 }
5231
5232 void G1CollectedHeap::increase_used(size_t bytes) {
5233 _summary_bytes_used += bytes;
5234 }
5235
5236 void G1CollectedHeap::decrease_used(size_t bytes) {
5237 assert(_summary_bytes_used >= bytes,
5238 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5239 _summary_bytes_used, bytes);
5240 _summary_bytes_used -= bytes;
5241 }
5242
5243 void G1CollectedHeap::set_used(size_t bytes) {
5244 _summary_bytes_used = bytes;
5245 }
5246
5247 class RebuildRegionSetsClosure : public HeapRegionClosure {
5248 private:
5249 bool _free_list_only;
5250 HeapRegionSet* _old_set;
5251 HeapRegionManager* _hrm;
5252 size_t _total_used;
5253
5254 public:
5255 RebuildRegionSetsClosure(bool free_list_only,
5256 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5257 _free_list_only(free_list_only),
5258 _old_set(old_set), _hrm(hrm), _total_used(0) {
5259 assert(_hrm->num_free_regions() == 0, "pre-condition");
5260 if (!free_list_only) {
5261 assert(_old_set->is_empty(), "pre-condition");
5262 }
5263 }
5264
5265 bool doHeapRegion(HeapRegion* r) {
5266 if (r->is_empty()) {
5267 // Add free regions to the free list
5268 r->set_free();
5269 r->set_allocation_context(AllocationContext::system());
5270 _hrm->insert_into_free_list(r);
5271 } else if (!_free_list_only) {
5272 assert(!r->is_young(), "we should not come across young regions");
5273
5274 if (r->is_humongous()) {
5275 // We ignore humongous regions. We left the humongous set unchanged.
5276 } else {
5277 // Objects that were compacted would have ended up on regions
5278 // that were previously old or free. Archive regions (which are
5279 // old) will not have been touched.
5280 assert(r->is_free() || r->is_old(), "invariant");
5281 // We now consider them old, so register as such. Leave
5282 // archive regions set that way, however, while still adding
5283 // them to the old set.
5284 if (!r->is_archive()) {
5285 r->set_old();
5286 }
5287 _old_set->add(r);
5288 }
5289 _total_used += r->used();
5290 }
5291
5292 return false;
5293 }
5294
5295 size_t total_used() {
5296 return _total_used;
5297 }
5298 };
5299
5300 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5301 assert_at_safepoint(true /* should_be_vm_thread */);
5302
5303 if (!free_list_only) {
5304 _young_list->empty_list();
5305 }
5306
5307 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5308 heap_region_iterate(&cl);
5309
5310 if (!free_list_only) {
5311 set_used(cl.total_used());
5312 if (_archive_allocator != NULL) {
5313 _archive_allocator->clear_used();
5314 }
5315 }
5316 assert(used_unlocked() == recalculate_used(),
5317 "inconsistent used_unlocked(), "
5318 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5319 used_unlocked(), recalculate_used());
5320 }
5321
5322 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5323 _refine_cte_cl->set_concurrent(concurrent);
5324 }
5325
5326 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5327 HeapRegion* hr = heap_region_containing(p);
5328 return hr->is_in(p);
5329 }
5330
5331 // Methods for the mutator alloc region
5332
5333 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5334 bool force) {
5335 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5336 assert(!force || g1_policy()->can_expand_young_list(),
5337 "if force is true we should be able to expand the young list");
5338 bool young_list_full = g1_policy()->is_young_list_full();
5339 if (force || !young_list_full) {
5340 HeapRegion* new_alloc_region = new_region(word_size,
5341 false /* is_old */,
5342 false /* do_expand */);
5343 if (new_alloc_region != NULL) {
5344 set_region_short_lived_locked(new_alloc_region);
5345 _hr_printer.alloc(new_alloc_region, young_list_full);
5346 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5347 return new_alloc_region;
5348 }
5349 }
5350 return NULL;
5351 }
5352
5353 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5354 size_t allocated_bytes) {
5355 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5356 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5357
5358 collection_set()->add_eden_region(alloc_region);
5359 increase_used(allocated_bytes);
5360 _hr_printer.retire(alloc_region);
5361 // We update the eden sizes here, when the region is retired,
5362 // instead of when it's allocated, since this is the point that its
5363 // used space has been recored in _summary_bytes_used.
5364 g1mm()->update_eden_size();
5365 }
5366
5367 // Methods for the GC alloc regions
5368
5369 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5370 if (dest.is_old()) {
5371 return true;
5372 } else {
5373 return young_list()->survivor_length() < g1_policy()->max_survivor_regions();
5374 }
5375 }
5376
5377 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5378 assert(FreeList_lock->owned_by_self(), "pre-condition");
5379
5380 if (!has_more_regions(dest)) {
5381 return NULL;
5382 }
5383
5384 const bool is_survivor = dest.is_young();
5385
5386 HeapRegion* new_alloc_region = new_region(word_size,
5387 !is_survivor,
5388 true /* do_expand */);
5389 if (new_alloc_region != NULL) {
5390 // We really only need to do this for old regions given that we
5391 // should never scan survivors. But it doesn't hurt to do it
5392 // for survivors too.
5393 new_alloc_region->record_timestamp();
5394 if (is_survivor) {
5395 new_alloc_region->set_survivor();
5396 young_list()->add_survivor_region(new_alloc_region);
5397 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5398 } else {
5399 new_alloc_region->set_old();
5400 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5401 }
5402 _hr_printer.alloc(new_alloc_region);
5403 bool during_im = collector_state()->during_initial_mark_pause();
5404 new_alloc_region->note_start_of_copying(during_im);
5405 return new_alloc_region;
5406 }
5407 return NULL;
5408 }
5409
5410 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5411 size_t allocated_bytes,
5412 InCSetState dest) {
5413 bool during_im = collector_state()->during_initial_mark_pause();
5414 alloc_region->note_end_of_copying(during_im);
5415 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5416 if (dest.is_old()) {
5417 _old_set.add(alloc_region);
5418 }
5419 _hr_printer.retire(alloc_region);
5420 }
5421
5422 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5423 bool expanded = false;
5424 uint index = _hrm.find_highest_free(&expanded);
5425
5426 if (index != G1_NO_HRM_INDEX) {
5427 if (expanded) {
5428 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5429 HeapRegion::GrainWords * HeapWordSize);
5430 }
5431 _hrm.allocate_free_regions_starting_at(index, 1);
5432 return region_at(index);
5433 }
5434 return NULL;
5435 }
5436
5437 // Optimized nmethod scanning
5438
5439 class RegisterNMethodOopClosure: public OopClosure {
5440 G1CollectedHeap* _g1h;
5441 nmethod* _nm;
5442
5443 template <class T> void do_oop_work(T* p) {
5444 T heap_oop = oopDesc::load_heap_oop(p);
5445 if (!oopDesc::is_null(heap_oop)) {
5446 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5447 HeapRegion* hr = _g1h->heap_region_containing(obj);
5448 assert(!hr->is_continues_humongous(),
5449 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5450 " starting at " HR_FORMAT,
5451 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5452
5453 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5454 hr->add_strong_code_root_locked(_nm);
5455 }
5456 }
5457
5458 public:
5459 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5460 _g1h(g1h), _nm(nm) {}
5461
5462 void do_oop(oop* p) { do_oop_work(p); }
5463 void do_oop(narrowOop* p) { do_oop_work(p); }
5464 };
5465
5466 class UnregisterNMethodOopClosure: public OopClosure {
5467 G1CollectedHeap* _g1h;
5468 nmethod* _nm;
5469
5470 template <class T> void do_oop_work(T* p) {
5471 T heap_oop = oopDesc::load_heap_oop(p);
5472 if (!oopDesc::is_null(heap_oop)) {
5473 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5474 HeapRegion* hr = _g1h->heap_region_containing(obj);
5475 assert(!hr->is_continues_humongous(),
5476 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5477 " starting at " HR_FORMAT,
5478 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5479
5480 hr->remove_strong_code_root(_nm);
5481 }
5482 }
5483
5484 public:
5485 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5486 _g1h(g1h), _nm(nm) {}
5487
5488 void do_oop(oop* p) { do_oop_work(p); }
5489 void do_oop(narrowOop* p) { do_oop_work(p); }
5490 };
5491
5492 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5493 CollectedHeap::register_nmethod(nm);
5494
5495 guarantee(nm != NULL, "sanity");
5496 RegisterNMethodOopClosure reg_cl(this, nm);
5497 nm->oops_do(®_cl);
5498 }
5499
5500 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5501 CollectedHeap::unregister_nmethod(nm);
5502
5503 guarantee(nm != NULL, "sanity");
5504 UnregisterNMethodOopClosure reg_cl(this, nm);
5505 nm->oops_do(®_cl, true);
5506 }
5507
5508 void G1CollectedHeap::purge_code_root_memory() {
5509 double purge_start = os::elapsedTime();
5510 G1CodeRootSet::purge();
5511 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5512 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5513 }
5514
5515 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5516 G1CollectedHeap* _g1h;
5517
5518 public:
5519 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5520 _g1h(g1h) {}
5521
5522 void do_code_blob(CodeBlob* cb) {
5523 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5524 if (nm == NULL) {
5525 return;
5526 }
5527
5528 if (ScavengeRootsInCode) {
5529 _g1h->register_nmethod(nm);
5530 }
5531 }
5532 };
5533
5534 void G1CollectedHeap::rebuild_strong_code_roots() {
5535 RebuildStrongCodeRootClosure blob_cl(this);
5536 CodeCache::blobs_do(&blob_cl);
5537 }