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