1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MarkSweep.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1YCTypes.hpp"
56 #include "gc/g1/heapRegion.inline.hpp"
57 #include "gc/g1/heapRegionRemSet.hpp"
58 #include "gc/g1/heapRegionSet.inline.hpp"
59 #include "gc/g1/suspendibleThreadSet.hpp"
60 #include "gc/g1/vm_operations_g1.hpp"
61 #include "gc/shared/gcHeapSummary.hpp"
62 #include "gc/shared/gcId.hpp"
63 #include "gc/shared/gcLocker.inline.hpp"
64 #include "gc/shared/gcTimer.hpp"
65 #include "gc/shared/gcTrace.hpp"
66 #include "gc/shared/gcTraceTime.inline.hpp"
67 #include "gc/shared/generationSpec.hpp"
68 #include "gc/shared/isGCActiveMark.hpp"
69 #include "gc/shared/preservedMarks.inline.hpp"
70 #include "gc/shared/referenceProcessor.inline.hpp"
71 #include "gc/shared/taskqueue.inline.hpp"
72 #include "logging/log.hpp"
73 #include "memory/allocation.hpp"
74 #include "memory/iterator.hpp"
75 #include "memory/resourceArea.hpp"
76 #include "oops/oop.inline.hpp"
77 #include "prims/resolvedMethodTable.hpp"
78 #include "runtime/atomic.hpp"
79 #include "runtime/init.hpp"
80 #include "runtime/orderAccess.inline.hpp"
81 #include "runtime/vmThread.hpp"
82 #include "utilities/align.hpp"
83 #include "utilities/globalDefinitions.hpp"
84 #include "utilities/stack.inline.hpp"
85
86 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
87
88 // INVARIANTS/NOTES
89 //
90 // All allocation activity covered by the G1CollectedHeap interface is
91 // serialized by acquiring the HeapLock. This happens in mem_allocate
92 // and allocate_new_tlab, which are the "entry" points to the
93 // allocation code from the rest of the JVM. (Note that this does not
94 // apply to TLAB allocation, which is not part of this interface: it
95 // is done by clients of this interface.)
96
97 // Local to this file.
98
99 class RefineCardTableEntryClosure: public CardTableEntryClosure {
100 bool _concurrent;
101 public:
102 RefineCardTableEntryClosure() : _concurrent(true) { }
103
104 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
105 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
120 private:
121 size_t _num_dirtied;
122 G1CollectedHeap* _g1h;
123 G1SATBCardTableLoggingModRefBS* _g1_bs;
124
125 HeapRegion* region_for_card(jbyte* card_ptr) const {
126 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
127 }
128
129 bool will_become_free(HeapRegion* hr) const {
130 // A region will be freed by free_collection_set if the region is in the
131 // collection set and has not had an evacuation failure.
132 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
133 }
134
135 public:
136 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
137 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
138
139 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
140 HeapRegion* hr = region_for_card(card_ptr);
141
142 // Should only dirty cards in regions that won't be freed.
143 if (!will_become_free(hr)) {
144 *card_ptr = CardTableModRefBS::dirty_card_val();
145 _num_dirtied++;
146 }
147
148 return true;
149 }
150
151 size_t num_dirtied() const { return _num_dirtied; }
152 };
153
154
155 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
156 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
157 }
158
159 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
160 // The from card cache is not the memory that is actually committed. So we cannot
161 // take advantage of the zero_filled parameter.
162 reset_from_card_cache(start_idx, num_regions);
163 }
164
165 // Returns true if the reference points to an object that
166 // can move in an incremental collection.
167 bool G1CollectedHeap::is_scavengable(const void* p) {
168 HeapRegion* hr = heap_region_containing(p);
169 return !hr->is_pinned();
170 }
171
172 // Private methods.
173
174 HeapRegion*
175 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
176 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
177 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
178 if (!_secondary_free_list.is_empty()) {
179 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
180 "secondary_free_list has %u entries",
181 _secondary_free_list.length());
182 // It looks as if there are free regions available on the
183 // secondary_free_list. Let's move them to the free_list and try
184 // again to allocate from it.
185 append_secondary_free_list();
186
187 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
188 "empty we should have moved at least one entry to the free_list");
189 HeapRegion* res = _hrm.allocate_free_region(is_old);
190 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
191 "allocated " HR_FORMAT " from secondary_free_list",
192 HR_FORMAT_PARAMS(res));
193 return res;
194 }
195
196 // Wait here until we get notified either when (a) there are no
197 // more free regions coming or (b) some regions have been moved on
198 // the secondary_free_list.
199 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
200 }
201
202 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
203 "could not allocate from secondary_free_list");
204 return NULL;
205 }
206
207 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
208 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
209 "the only time we use this to allocate a humongous region is "
210 "when we are allocating a single humongous region");
211
212 HeapRegion* res;
213 if (G1StressConcRegionFreeing) {
214 if (!_secondary_free_list.is_empty()) {
215 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
216 "forced to look at the secondary_free_list");
217 res = new_region_try_secondary_free_list(is_old);
218 if (res != NULL) {
219 return res;
220 }
221 }
222 }
223
224 res = _hrm.allocate_free_region(is_old);
225
226 if (res == NULL) {
227 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
228 "res == NULL, trying the secondary_free_list");
229 res = new_region_try_secondary_free_list(is_old);
230 }
231 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
232 // Currently, only attempts to allocate GC alloc regions set
233 // do_expand to true. So, we should only reach here during a
234 // safepoint. If this assumption changes we might have to
235 // reconsider the use of _expand_heap_after_alloc_failure.
236 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
237
238 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
239 word_size * HeapWordSize);
240
241 if (expand(word_size * HeapWordSize)) {
242 // Given that expand() succeeded in expanding the heap, and we
243 // always expand the heap by an amount aligned to the heap
244 // region size, the free list should in theory not be empty.
245 // In either case allocate_free_region() will check for NULL.
246 res = _hrm.allocate_free_region(is_old);
247 } else {
248 _expand_heap_after_alloc_failure = false;
249 }
250 }
251 return res;
252 }
253
254 HeapWord*
255 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
256 uint num_regions,
257 size_t word_size,
258 AllocationContext_t context) {
259 assert(first != G1_NO_HRM_INDEX, "pre-condition");
260 assert(is_humongous(word_size), "word_size should be humongous");
261 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
262
263 // Index of last region in the series.
264 uint last = first + num_regions - 1;
265
266 // We need to initialize the region(s) we just discovered. This is
267 // a bit tricky given that it can happen concurrently with
268 // refinement threads refining cards on these regions and
269 // potentially wanting to refine the BOT as they are scanning
270 // those cards (this can happen shortly after a cleanup; see CR
271 // 6991377). So we have to set up the region(s) carefully and in
272 // a specific order.
273
274 // The word size sum of all the regions we will allocate.
275 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
276 assert(word_size <= word_size_sum, "sanity");
277
278 // This will be the "starts humongous" region.
279 HeapRegion* first_hr = region_at(first);
280 // The header of the new object will be placed at the bottom of
281 // the first region.
282 HeapWord* new_obj = first_hr->bottom();
283 // This will be the new top of the new object.
284 HeapWord* obj_top = new_obj + word_size;
285
286 // First, we need to zero the header of the space that we will be
287 // allocating. When we update top further down, some refinement
288 // threads might try to scan the region. By zeroing the header we
289 // ensure that any thread that will try to scan the region will
290 // come across the zero klass word and bail out.
291 //
292 // NOTE: It would not have been correct to have used
293 // CollectedHeap::fill_with_object() and make the space look like
294 // an int array. The thread that is doing the allocation will
295 // later update the object header to a potentially different array
296 // type and, for a very short period of time, the klass and length
297 // fields will be inconsistent. This could cause a refinement
298 // thread to calculate the object size incorrectly.
299 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
300
301 // Next, pad out the unused tail of the last region with filler
302 // objects, for improved usage accounting.
303 // How many words we use for filler objects.
304 size_t word_fill_size = word_size_sum - word_size;
305
306 // How many words memory we "waste" which cannot hold a filler object.
307 size_t words_not_fillable = 0;
308
309 if (word_fill_size >= min_fill_size()) {
310 fill_with_objects(obj_top, word_fill_size);
311 } else if (word_fill_size > 0) {
312 // We have space to fill, but we cannot fit an object there.
313 words_not_fillable = word_fill_size;
314 word_fill_size = 0;
315 }
316
317 // We will set up the first region as "starts humongous". This
318 // will also update the BOT covering all the regions to reflect
319 // that there is a single object that starts at the bottom of the
320 // first region.
321 first_hr->set_starts_humongous(obj_top, word_fill_size);
322 first_hr->set_allocation_context(context);
323 // Then, if there are any, we will set up the "continues
324 // humongous" regions.
325 HeapRegion* hr = NULL;
326 for (uint i = first + 1; i <= last; ++i) {
327 hr = region_at(i);
328 hr->set_continues_humongous(first_hr);
329 hr->set_allocation_context(context);
330 }
331
332 // Up to this point no concurrent thread would have been able to
333 // do any scanning on any region in this series. All the top
334 // fields still point to bottom, so the intersection between
335 // [bottom,top] and [card_start,card_end] will be empty. Before we
336 // update the top fields, we'll do a storestore to make sure that
337 // no thread sees the update to top before the zeroing of the
338 // object header and the BOT initialization.
339 OrderAccess::storestore();
340
341 // Now, we will update the top fields of the "continues humongous"
342 // regions except the last one.
343 for (uint i = first; i < last; ++i) {
344 hr = region_at(i);
345 hr->set_top(hr->end());
346 }
347
348 hr = region_at(last);
349 // If we cannot fit a filler object, we must set top to the end
350 // of the humongous object, otherwise we cannot iterate the heap
351 // and the BOT will not be complete.
352 hr->set_top(hr->end() - words_not_fillable);
353
354 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
355 "obj_top should be in last region");
356
357 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
358
359 assert(words_not_fillable == 0 ||
360 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
361 "Miscalculation in humongous allocation");
362
363 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
364
365 for (uint i = first; i <= last; ++i) {
366 hr = region_at(i);
367 _humongous_set.add(hr);
368 _hr_printer.alloc(hr);
369 }
370
371 return new_obj;
372 }
373
374 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
375 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
376 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
377 }
378
379 // If could fit into free regions w/o expansion, try.
380 // Otherwise, if can expand, do so.
381 // Otherwise, if using ex regions might help, try with ex given back.
382 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
383 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
384
385 _verifier->verify_region_sets_optional();
386
387 uint first = G1_NO_HRM_INDEX;
388 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
389
390 if (obj_regions == 1) {
391 // Only one region to allocate, try to use a fast path by directly allocating
392 // from the free lists. Do not try to expand here, we will potentially do that
393 // later.
394 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
395 if (hr != NULL) {
396 first = hr->hrm_index();
397 }
398 } else {
399 // We can't allocate humongous regions spanning more than one region while
400 // cleanupComplete() is running, since some of the regions we find to be
401 // empty might not yet be added to the free list. It is not straightforward
402 // to know in which list they are on so that we can remove them. We only
403 // need to do this if we need to allocate more than one region to satisfy the
404 // current humongous allocation request. If we are only allocating one region
405 // we use the one-region region allocation code (see above), that already
406 // potentially waits for regions from the secondary free list.
407 wait_while_free_regions_coming();
408 append_secondary_free_list_if_not_empty_with_lock();
409
410 // Policy: Try only empty regions (i.e. already committed first). Maybe we
411 // are lucky enough to find some.
412 first = _hrm.find_contiguous_only_empty(obj_regions);
413 if (first != G1_NO_HRM_INDEX) {
414 _hrm.allocate_free_regions_starting_at(first, obj_regions);
415 }
416 }
417
418 if (first == G1_NO_HRM_INDEX) {
419 // Policy: We could not find enough regions for the humongous object in the
420 // free list. Look through the heap to find a mix of free and uncommitted regions.
421 // If so, try expansion.
422 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
423 if (first != G1_NO_HRM_INDEX) {
424 // We found something. Make sure these regions are committed, i.e. expand
425 // the heap. Alternatively we could do a defragmentation GC.
426 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
427 word_size * HeapWordSize);
428
429 _hrm.expand_at(first, obj_regions, workers());
430 g1_policy()->record_new_heap_size(num_regions());
431
432 #ifdef ASSERT
433 for (uint i = first; i < first + obj_regions; ++i) {
434 HeapRegion* hr = region_at(i);
435 assert(hr->is_free(), "sanity");
436 assert(hr->is_empty(), "sanity");
437 assert(is_on_master_free_list(hr), "sanity");
438 }
439 #endif
440 _hrm.allocate_free_regions_starting_at(first, obj_regions);
441 } else {
442 // Policy: Potentially trigger a defragmentation GC.
443 }
444 }
445
446 HeapWord* result = NULL;
447 if (first != G1_NO_HRM_INDEX) {
448 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
449 word_size, context);
450 assert(result != NULL, "it should always return a valid result");
451
452 // A successful humongous object allocation changes the used space
453 // information of the old generation so we need to recalculate the
454 // sizes and update the jstat counters here.
455 g1mm()->update_sizes();
456 }
457
458 _verifier->verify_region_sets_optional();
459
460 return result;
461 }
462
463 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
464 assert_heap_not_locked_and_not_at_safepoint();
465 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
466
467 uint dummy_gc_count_before;
468 uint dummy_gclocker_retry_count = 0;
469 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
470 }
471
472 HeapWord*
473 G1CollectedHeap::mem_allocate(size_t word_size,
474 bool* gc_overhead_limit_was_exceeded) {
475 assert_heap_not_locked_and_not_at_safepoint();
476
477 // Loop until the allocation is satisfied, or unsatisfied after GC.
478 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
479 uint gc_count_before;
480
481 HeapWord* result = NULL;
482 if (!is_humongous(word_size)) {
483 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
484 } else {
485 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
486 }
487 if (result != NULL) {
488 return result;
489 }
490
491 // Create the garbage collection operation...
492 VM_G1CollectForAllocation op(gc_count_before, word_size);
493 op.set_allocation_context(AllocationContext::current());
494
495 // ...and get the VM thread to execute it.
496 VMThread::execute(&op);
497
498 if (op.prologue_succeeded() && op.pause_succeeded()) {
499 // If the operation was successful we'll return the result even
500 // if it is NULL. If the allocation attempt failed immediately
501 // after a Full GC, it's unlikely we'll be able to allocate now.
502 HeapWord* result = op.result();
503 if (result != NULL && !is_humongous(word_size)) {
504 // Allocations that take place on VM operations do not do any
505 // card dirtying and we have to do it here. We only have to do
506 // this for non-humongous allocations, though.
507 dirty_young_block(result, word_size);
508 }
509 return result;
510 } else {
511 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
512 return NULL;
513 }
514 assert(op.result() == NULL,
515 "the result should be NULL if the VM op did not succeed");
516 }
517
518 // Give a warning if we seem to be looping forever.
519 if ((QueuedAllocationWarningCount > 0) &&
520 (try_count % QueuedAllocationWarningCount == 0)) {
521 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
522 }
523 }
524
525 ShouldNotReachHere();
526 return NULL;
527 }
528
529 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
530 AllocationContext_t context,
531 uint* gc_count_before_ret,
532 uint* gclocker_retry_count_ret) {
533 // Make sure you read the note in attempt_allocation_humongous().
534
535 assert_heap_not_locked_and_not_at_safepoint();
536 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
537 "be called for humongous allocation requests");
538
539 // We should only get here after the first-level allocation attempt
540 // (attempt_allocation()) failed to allocate.
541
542 // We will loop until a) we manage to successfully perform the
543 // allocation or b) we successfully schedule a collection which
544 // fails to perform the allocation. b) is the only case when we'll
545 // return NULL.
546 HeapWord* result = NULL;
547 for (int try_count = 1; /* we'll return */; try_count += 1) {
548 bool should_try_gc;
549 uint gc_count_before;
550
551 {
552 MutexLockerEx x(Heap_lock);
553 result = _allocator->attempt_allocation_locked(word_size, context);
554 if (result != NULL) {
555 return result;
556 }
557
558 if (GCLocker::is_active_and_needs_gc()) {
559 if (g1_policy()->can_expand_young_list()) {
560 // No need for an ergo verbose message here,
561 // can_expand_young_list() does this when it returns true.
562 result = _allocator->attempt_allocation_force(word_size, context);
563 if (result != NULL) {
564 return result;
565 }
566 }
567 should_try_gc = false;
568 } else {
569 // The GCLocker may not be active but the GCLocker initiated
570 // GC may not yet have been performed (GCLocker::needs_gc()
571 // returns true). In this case we do not try this GC and
572 // wait until the GCLocker initiated GC is performed, and
573 // then retry the allocation.
574 if (GCLocker::needs_gc()) {
575 should_try_gc = false;
576 } else {
577 // Read the GC count while still holding the Heap_lock.
578 gc_count_before = total_collections();
579 should_try_gc = true;
580 }
581 }
582 }
583
584 if (should_try_gc) {
585 bool succeeded;
586 result = do_collection_pause(word_size, gc_count_before, &succeeded,
587 GCCause::_g1_inc_collection_pause);
588 if (result != NULL) {
589 assert(succeeded, "only way to get back a non-NULL result");
590 return result;
591 }
592
593 if (succeeded) {
594 // If we get here we successfully scheduled a collection which
595 // failed to allocate. No point in trying to allocate
596 // further. We'll just return NULL.
597 MutexLockerEx x(Heap_lock);
598 *gc_count_before_ret = total_collections();
599 return NULL;
600 }
601 } else {
602 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
603 MutexLockerEx x(Heap_lock);
604 *gc_count_before_ret = total_collections();
605 return NULL;
606 }
607 // The GCLocker is either active or the GCLocker initiated
608 // GC has not yet been performed. Stall until it is and
609 // then retry the allocation.
610 GCLocker::stall_until_clear();
611 (*gclocker_retry_count_ret) += 1;
612 }
613
614 // We can reach here if we were unsuccessful in scheduling a
615 // collection (because another thread beat us to it) or if we were
616 // stalled due to the GC locker. In either can we should retry the
617 // allocation attempt in case another thread successfully
618 // performed a collection and reclaimed enough space. We do the
619 // first attempt (without holding the Heap_lock) here and the
620 // follow-on attempt will be at the start of the next loop
621 // iteration (after taking the Heap_lock).
622 result = _allocator->attempt_allocation(word_size, context);
623 if (result != NULL) {
624 return result;
625 }
626
627 // Give a warning if we seem to be looping forever.
628 if ((QueuedAllocationWarningCount > 0) &&
629 (try_count % QueuedAllocationWarningCount == 0)) {
630 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
631 "retries %d times", try_count);
632 }
633 }
634
635 ShouldNotReachHere();
636 return NULL;
637 }
638
639 void G1CollectedHeap::begin_archive_alloc_range() {
640 assert_at_safepoint(true /* should_be_vm_thread */);
641 if (_archive_allocator == NULL) {
642 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
643 }
644 }
645
646 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
647 // Allocations in archive regions cannot be of a size that would be considered
648 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
649 // may be different at archive-restore time.
650 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
651 }
652
653 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
654 assert_at_safepoint(true /* should_be_vm_thread */);
655 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
656 if (is_archive_alloc_too_large(word_size)) {
657 return NULL;
658 }
659 return _archive_allocator->archive_mem_allocate(word_size);
660 }
661
662 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
663 size_t end_alignment_in_bytes) {
664 assert_at_safepoint(true /* should_be_vm_thread */);
665 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
666
667 // Call complete_archive to do the real work, filling in the MemRegion
668 // array with the archive regions.
669 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
670 delete _archive_allocator;
671 _archive_allocator = NULL;
672 }
673
674 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
675 assert(ranges != NULL, "MemRegion array NULL");
676 assert(count != 0, "No MemRegions provided");
677 MemRegion reserved = _hrm.reserved();
678 for (size_t i = 0; i < count; i++) {
679 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
680 return false;
681 }
682 }
683 return true;
684 }
685
686 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
687 assert(!is_init_completed(), "Expect to be called at JVM init time");
688 assert(ranges != NULL, "MemRegion array NULL");
689 assert(count != 0, "No MemRegions provided");
690 MutexLockerEx x(Heap_lock);
691
692 MemRegion reserved = _hrm.reserved();
693 HeapWord* prev_last_addr = NULL;
694 HeapRegion* prev_last_region = NULL;
695
696 // Temporarily disable pretouching of heap pages. This interface is used
697 // when mmap'ing archived heap data in, so pre-touching is wasted.
698 FlagSetting fs(AlwaysPreTouch, false);
699
700 // Enable archive object checking used by G1MarkSweep. We have to let it know
701 // about each archive range, so that objects in those ranges aren't marked.
702 G1ArchiveAllocator::enable_archive_object_check();
703
704 // For each specified MemRegion range, allocate the corresponding G1
705 // regions and mark them as archive regions. We expect the ranges in
706 // ascending starting address order, without overlap.
707 for (size_t i = 0; i < count; i++) {
708 MemRegion curr_range = ranges[i];
709 HeapWord* start_address = curr_range.start();
710 size_t word_size = curr_range.word_size();
711 HeapWord* last_address = curr_range.last();
712 size_t commits = 0;
713
714 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
715 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
716 p2i(start_address), p2i(last_address));
717 guarantee(start_address > prev_last_addr,
718 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
719 p2i(start_address), p2i(prev_last_addr));
720 prev_last_addr = last_address;
721
722 // Check for ranges that start in the same G1 region in which the previous
723 // range ended, and adjust the start address so we don't try to allocate
724 // the same region again. If the current range is entirely within that
725 // region, skip it, just adjusting the recorded top.
726 HeapRegion* start_region = _hrm.addr_to_region(start_address);
727 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
728 start_address = start_region->end();
729 if (start_address > last_address) {
730 increase_used(word_size * HeapWordSize);
731 start_region->set_top(last_address + 1);
732 continue;
733 }
734 start_region->set_top(start_address);
735 curr_range = MemRegion(start_address, last_address + 1);
736 start_region = _hrm.addr_to_region(start_address);
737 }
738
739 // Perform the actual region allocation, exiting if it fails.
740 // Then note how much new space we have allocated.
741 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
742 return false;
743 }
744 increase_used(word_size * HeapWordSize);
745 if (commits != 0) {
746 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
747 HeapRegion::GrainWords * HeapWordSize * commits);
748
749 }
750
751 // Mark each G1 region touched by the range as archive, add it to the old set,
752 // and set the allocation context and top.
753 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
754 HeapRegion* last_region = _hrm.addr_to_region(last_address);
755 prev_last_region = last_region;
756
757 while (curr_region != NULL) {
758 assert(curr_region->is_empty() && !curr_region->is_pinned(),
759 "Region already in use (index %u)", curr_region->hrm_index());
760 curr_region->set_allocation_context(AllocationContext::system());
761 curr_region->set_archive();
762 _hr_printer.alloc(curr_region);
763 _old_set.add(curr_region);
764 if (curr_region != last_region) {
765 curr_region->set_top(curr_region->end());
766 curr_region = _hrm.next_region_in_heap(curr_region);
767 } else {
768 curr_region->set_top(last_address + 1);
769 curr_region = NULL;
770 }
771 }
772
773 // Notify mark-sweep of the archive range.
774 G1ArchiveAllocator::set_range_archive(curr_range, true);
775 }
776 return true;
777 }
778
779 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
780 assert(!is_init_completed(), "Expect to be called at JVM init time");
781 assert(ranges != NULL, "MemRegion array NULL");
782 assert(count != 0, "No MemRegions provided");
783 MemRegion reserved = _hrm.reserved();
784 HeapWord *prev_last_addr = NULL;
785 HeapRegion* prev_last_region = NULL;
786
787 // For each MemRegion, create filler objects, if needed, in the G1 regions
788 // that contain the address range. The address range actually within the
789 // MemRegion will not be modified. That is assumed to have been initialized
790 // elsewhere, probably via an mmap of archived heap data.
791 MutexLockerEx x(Heap_lock);
792 for (size_t i = 0; i < count; i++) {
793 HeapWord* start_address = ranges[i].start();
794 HeapWord* last_address = ranges[i].last();
795
796 assert(reserved.contains(start_address) && reserved.contains(last_address),
797 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
798 p2i(start_address), p2i(last_address));
799 assert(start_address > prev_last_addr,
800 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
801 p2i(start_address), p2i(prev_last_addr));
802
803 HeapRegion* start_region = _hrm.addr_to_region(start_address);
804 HeapRegion* last_region = _hrm.addr_to_region(last_address);
805 HeapWord* bottom_address = start_region->bottom();
806
807 // Check for a range beginning in the same region in which the
808 // previous one ended.
809 if (start_region == prev_last_region) {
810 bottom_address = prev_last_addr + 1;
811 }
812
813 // Verify that the regions were all marked as archive regions by
814 // alloc_archive_regions.
815 HeapRegion* curr_region = start_region;
816 while (curr_region != NULL) {
817 guarantee(curr_region->is_archive(),
818 "Expected archive region at index %u", curr_region->hrm_index());
819 if (curr_region != last_region) {
820 curr_region = _hrm.next_region_in_heap(curr_region);
821 } else {
822 curr_region = NULL;
823 }
824 }
825
826 prev_last_addr = last_address;
827 prev_last_region = last_region;
828
829 // Fill the memory below the allocated range with dummy object(s),
830 // if the region bottom does not match the range start, or if the previous
831 // range ended within the same G1 region, and there is a gap.
832 if (start_address != bottom_address) {
833 size_t fill_size = pointer_delta(start_address, bottom_address);
834 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
835 increase_used(fill_size * HeapWordSize);
836 }
837 }
838 }
839
840 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
841 uint* gc_count_before_ret,
842 uint* gclocker_retry_count_ret) {
843 assert_heap_not_locked_and_not_at_safepoint();
844 assert(!is_humongous(word_size), "attempt_allocation() should not "
845 "be called for humongous allocation requests");
846
847 AllocationContext_t context = AllocationContext::current();
848 HeapWord* result = _allocator->attempt_allocation(word_size, context);
849
850 if (result == NULL) {
851 result = attempt_allocation_slow(word_size,
852 context,
853 gc_count_before_ret,
854 gclocker_retry_count_ret);
855 }
856 assert_heap_not_locked();
857 if (result != NULL) {
858 dirty_young_block(result, word_size);
859 }
860 return result;
861 }
862
863 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
864 assert(!is_init_completed(), "Expect to be called at JVM init time");
865 assert(ranges != NULL, "MemRegion array NULL");
866 assert(count != 0, "No MemRegions provided");
867 MemRegion reserved = _hrm.reserved();
868 HeapWord* prev_last_addr = NULL;
869 HeapRegion* prev_last_region = NULL;
870 size_t size_used = 0;
871 size_t uncommitted_regions = 0;
872
873 // For each Memregion, free the G1 regions that constitute it, and
874 // notify mark-sweep that the range is no longer to be considered 'archive.'
875 MutexLockerEx x(Heap_lock);
876 for (size_t i = 0; i < count; i++) {
877 HeapWord* start_address = ranges[i].start();
878 HeapWord* last_address = ranges[i].last();
879
880 assert(reserved.contains(start_address) && reserved.contains(last_address),
881 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
882 p2i(start_address), p2i(last_address));
883 assert(start_address > prev_last_addr,
884 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
885 p2i(start_address), p2i(prev_last_addr));
886 size_used += ranges[i].byte_size();
887 prev_last_addr = last_address;
888
889 HeapRegion* start_region = _hrm.addr_to_region(start_address);
890 HeapRegion* last_region = _hrm.addr_to_region(last_address);
891
892 // Check for ranges that start in the same G1 region in which the previous
893 // range ended, and adjust the start address so we don't try to free
894 // the same region again. If the current range is entirely within that
895 // region, skip it.
896 if (start_region == prev_last_region) {
897 start_address = start_region->end();
898 if (start_address > last_address) {
899 continue;
900 }
901 start_region = _hrm.addr_to_region(start_address);
902 }
903 prev_last_region = last_region;
904
905 // After verifying that each region was marked as an archive region by
906 // alloc_archive_regions, set it free and empty and uncommit it.
907 HeapRegion* curr_region = start_region;
908 while (curr_region != NULL) {
909 guarantee(curr_region->is_archive(),
910 "Expected archive region at index %u", curr_region->hrm_index());
911 uint curr_index = curr_region->hrm_index();
912 _old_set.remove(curr_region);
913 curr_region->set_free();
914 curr_region->set_top(curr_region->bottom());
915 if (curr_region != last_region) {
916 curr_region = _hrm.next_region_in_heap(curr_region);
917 } else {
918 curr_region = NULL;
919 }
920 _hrm.shrink_at(curr_index, 1);
921 uncommitted_regions++;
922 }
923
924 // Notify mark-sweep that this is no longer an archive range.
925 G1ArchiveAllocator::set_range_archive(ranges[i], false);
926 }
927
928 if (uncommitted_regions != 0) {
929 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
930 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
931 }
932 decrease_used(size_used);
933 }
934
935 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
936 uint* gc_count_before_ret,
937 uint* gclocker_retry_count_ret) {
938 // The structure of this method has a lot of similarities to
939 // attempt_allocation_slow(). The reason these two were not merged
940 // into a single one is that such a method would require several "if
941 // allocation is not humongous do this, otherwise do that"
942 // conditional paths which would obscure its flow. In fact, an early
943 // version of this code did use a unified method which was harder to
944 // follow and, as a result, it had subtle bugs that were hard to
945 // track down. So keeping these two methods separate allows each to
946 // be more readable. It will be good to keep these two in sync as
947 // much as possible.
948
949 assert_heap_not_locked_and_not_at_safepoint();
950 assert(is_humongous(word_size), "attempt_allocation_humongous() "
951 "should only be called for humongous allocations");
952
953 // Humongous objects can exhaust the heap quickly, so we should check if we
954 // need to start a marking cycle at each humongous object allocation. We do
955 // the check before we do the actual allocation. The reason for doing it
956 // before the allocation is that we avoid having to keep track of the newly
957 // allocated memory while we do a GC.
958 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
959 word_size)) {
960 collect(GCCause::_g1_humongous_allocation);
961 }
962
963 // We will loop until a) we manage to successfully perform the
964 // allocation or b) we successfully schedule a collection which
965 // fails to perform the allocation. b) is the only case when we'll
966 // return NULL.
967 HeapWord* result = NULL;
968 for (int try_count = 1; /* we'll return */; try_count += 1) {
969 bool should_try_gc;
970 uint gc_count_before;
971
972 {
973 MutexLockerEx x(Heap_lock);
974
975 // Given that humongous objects are not allocated in young
976 // regions, we'll first try to do the allocation without doing a
977 // collection hoping that there's enough space in the heap.
978 result = humongous_obj_allocate(word_size, AllocationContext::current());
979 if (result != NULL) {
980 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
981 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
982 return result;
983 }
984
985 if (GCLocker::is_active_and_needs_gc()) {
986 should_try_gc = false;
987 } else {
988 // The GCLocker may not be active but the GCLocker initiated
989 // GC may not yet have been performed (GCLocker::needs_gc()
990 // returns true). In this case we do not try this GC and
991 // wait until the GCLocker initiated GC is performed, and
992 // then retry the allocation.
993 if (GCLocker::needs_gc()) {
994 should_try_gc = false;
995 } else {
996 // Read the GC count while still holding the Heap_lock.
997 gc_count_before = total_collections();
998 should_try_gc = true;
999 }
1000 }
1001 }
1002
1003 if (should_try_gc) {
1004 // If we failed to allocate the humongous object, we should try to
1005 // do a collection pause (if we're allowed) in case it reclaims
1006 // enough space for the allocation to succeed after the pause.
1007
1008 bool succeeded;
1009 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1010 GCCause::_g1_humongous_allocation);
1011 if (result != NULL) {
1012 assert(succeeded, "only way to get back a non-NULL result");
1013 return result;
1014 }
1015
1016 if (succeeded) {
1017 // If we get here we successfully scheduled a collection which
1018 // failed to allocate. No point in trying to allocate
1019 // further. We'll just return NULL.
1020 MutexLockerEx x(Heap_lock);
1021 *gc_count_before_ret = total_collections();
1022 return NULL;
1023 }
1024 } else {
1025 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1026 MutexLockerEx x(Heap_lock);
1027 *gc_count_before_ret = total_collections();
1028 return NULL;
1029 }
1030 // The GCLocker is either active or the GCLocker initiated
1031 // GC has not yet been performed. Stall until it is and
1032 // then retry the allocation.
1033 GCLocker::stall_until_clear();
1034 (*gclocker_retry_count_ret) += 1;
1035 }
1036
1037 // We can reach here if we were unsuccessful in scheduling a
1038 // collection (because another thread beat us to it) or if we were
1039 // stalled due to the GC locker. In either can we should retry the
1040 // allocation attempt in case another thread successfully
1041 // performed a collection and reclaimed enough space. Give a
1042 // warning if we seem to be looping forever.
1043
1044 if ((QueuedAllocationWarningCount > 0) &&
1045 (try_count % QueuedAllocationWarningCount == 0)) {
1046 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1047 "retries %d times", try_count);
1048 }
1049 }
1050
1051 ShouldNotReachHere();
1052 return NULL;
1053 }
1054
1055 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1056 AllocationContext_t context,
1057 bool expect_null_mutator_alloc_region) {
1058 assert_at_safepoint(true /* should_be_vm_thread */);
1059 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1060 "the current alloc region was unexpectedly found to be non-NULL");
1061
1062 if (!is_humongous(word_size)) {
1063 return _allocator->attempt_allocation_locked(word_size, context);
1064 } else {
1065 HeapWord* result = humongous_obj_allocate(word_size, context);
1066 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1067 collector_state()->set_initiate_conc_mark_if_possible(true);
1068 }
1069 return result;
1070 }
1071
1072 ShouldNotReachHere();
1073 }
1074
1075 class PostMCRemSetClearClosure: public HeapRegionClosure {
1076 G1CollectedHeap* _g1h;
1077 ModRefBarrierSet* _mr_bs;
1078 public:
1079 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1080 _g1h(g1h), _mr_bs(mr_bs) {}
1081
1082 bool doHeapRegion(HeapRegion* r) {
1083 HeapRegionRemSet* hrrs = r->rem_set();
1084
1085 _g1h->reset_gc_time_stamps(r);
1086
1087 if (r->is_continues_humongous()) {
1088 // We'll assert that the strong code root list and RSet is empty
1089 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1090 assert(hrrs->occupied() == 0, "RSet should be empty");
1091 } else {
1092 hrrs->clear();
1093 }
1094 // You might think here that we could clear just the cards
1095 // corresponding to the used region. But no: if we leave a dirty card
1096 // in a region we might allocate into, then it would prevent that card
1097 // from being enqueued, and cause it to be missed.
1098 // Re: the performance cost: we shouldn't be doing full GC anyway!
1099 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1100
1101 return false;
1102 }
1103 };
1104
1105 void G1CollectedHeap::clear_rsets_post_compaction() {
1106 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1107 heap_region_iterate(&rs_clear);
1108 }
1109
1110 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1111 G1CollectedHeap* _g1h;
1112 RebuildRSOopClosure _cl;
1113 public:
1114 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1115 _cl(g1->g1_rem_set(), worker_i),
1116 _g1h(g1)
1117 { }
1118
1119 bool doHeapRegion(HeapRegion* r) {
1120 if (!r->is_continues_humongous()) {
1121 _cl.set_from(r);
1122 r->oop_iterate(&_cl);
1123 }
1124 return false;
1125 }
1126 };
1127
1128 class ParRebuildRSTask: public AbstractGangTask {
1129 G1CollectedHeap* _g1;
1130 HeapRegionClaimer _hrclaimer;
1131
1132 public:
1133 ParRebuildRSTask(G1CollectedHeap* g1) :
1134 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1135
1136 void work(uint worker_id) {
1137 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1138 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1139 }
1140 };
1141
1142 class PostCompactionPrinterClosure: public HeapRegionClosure {
1143 private:
1144 G1HRPrinter* _hr_printer;
1145 public:
1146 bool doHeapRegion(HeapRegion* hr) {
1147 assert(!hr->is_young(), "not expecting to find young regions");
1148 _hr_printer->post_compaction(hr);
1149 return false;
1150 }
1151
1152 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1153 : _hr_printer(hr_printer) { }
1154 };
1155
1156 void G1CollectedHeap::print_hrm_post_compaction() {
1157 if (_hr_printer.is_active()) {
1158 PostCompactionPrinterClosure cl(hr_printer());
1159 heap_region_iterate(&cl);
1160 }
1161
1162 }
1163
1164 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1165 bool clear_all_soft_refs) {
1166 assert_at_safepoint(true /* should_be_vm_thread */);
1167
1168 if (GCLocker::check_active_before_gc()) {
1169 return false;
1170 }
1171
1172 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1173 gc_timer->register_gc_start();
1174
1175 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1176 GCIdMark gc_id_mark;
1177 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1178
1179 SvcGCMarker sgcm(SvcGCMarker::FULL);
1180 ResourceMark rm;
1181
1182 print_heap_before_gc();
1183 print_heap_regions();
1184 trace_heap_before_gc(gc_tracer);
1185
1186 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1187
1188 _verifier->verify_region_sets_optional();
1189
1190 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1191 collector_policy()->should_clear_all_soft_refs();
1192
1193 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1194
1195 {
1196 IsGCActiveMark x;
1197
1198 // Timing
1199 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1200 GCTraceCPUTime tcpu;
1201
1202 {
1203 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1204 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1205 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1206
1207 G1HeapTransition heap_transition(this);
1208 g1_policy()->record_full_collection_start();
1209
1210 // Note: When we have a more flexible GC logging framework that
1211 // allows us to add optional attributes to a GC log record we
1212 // could consider timing and reporting how long we wait in the
1213 // following two methods.
1214 wait_while_free_regions_coming();
1215 // If we start the compaction before the CM threads finish
1216 // scanning the root regions we might trip them over as we'll
1217 // be moving objects / updating references. So let's wait until
1218 // they are done. By telling them to abort, they should complete
1219 // early.
1220 _cm->root_regions()->abort();
1221 _cm->root_regions()->wait_until_scan_finished();
1222 append_secondary_free_list_if_not_empty_with_lock();
1223
1224 gc_prologue(true);
1225 increment_total_collections(true /* full gc */);
1226 increment_old_marking_cycles_started();
1227
1228 assert(used() == recalculate_used(), "Should be equal");
1229
1230 _verifier->verify_before_gc();
1231
1232 _verifier->check_bitmaps("Full GC Start");
1233 pre_full_gc_dump(gc_timer);
1234
1235 #if defined(COMPILER2) || INCLUDE_JVMCI
1236 DerivedPointerTable::clear();
1237 #endif
1238
1239 // Disable discovery and empty the discovered lists
1240 // for the CM ref processor.
1241 ref_processor_cm()->disable_discovery();
1242 ref_processor_cm()->abandon_partial_discovery();
1243 ref_processor_cm()->verify_no_references_recorded();
1244
1245 // Abandon current iterations of concurrent marking and concurrent
1246 // refinement, if any are in progress.
1247 concurrent_mark()->abort();
1248
1249 // Make sure we'll choose a new allocation region afterwards.
1250 _allocator->release_mutator_alloc_region();
1251 _allocator->abandon_gc_alloc_regions();
1252 g1_rem_set()->cleanupHRRS();
1253
1254 // We may have added regions to the current incremental collection
1255 // set between the last GC or pause and now. We need to clear the
1256 // incremental collection set and then start rebuilding it afresh
1257 // after this full GC.
1258 abandon_collection_set(collection_set());
1259
1260 tear_down_region_sets(false /* free_list_only */);
1261 collector_state()->set_gcs_are_young(true);
1262
1263 // See the comments in g1CollectedHeap.hpp and
1264 // G1CollectedHeap::ref_processing_init() about
1265 // how reference processing currently works in G1.
1266
1267 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1268 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1269
1270 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1271 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1272
1273 ref_processor_stw()->enable_discovery();
1274 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1275
1276 // Do collection work
1277 {
1278 HandleMark hm; // Discard invalid handles created during gc
1279 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1280 }
1281
1282 assert(num_free_regions() == 0, "we should not have added any free regions");
1283 rebuild_region_sets(false /* free_list_only */);
1284
1285 // Enqueue any discovered reference objects that have
1286 // not been removed from the discovered lists.
1287 ref_processor_stw()->enqueue_discovered_references();
1288
1289 #if defined(COMPILER2) || INCLUDE_JVMCI
1290 DerivedPointerTable::update_pointers();
1291 #endif
1292
1293 MemoryService::track_memory_usage();
1294
1295 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1296 ref_processor_stw()->verify_no_references_recorded();
1297
1298 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1299 ClassLoaderDataGraph::purge();
1300 MetaspaceAux::verify_metrics();
1301
1302 // Note: since we've just done a full GC, concurrent
1303 // marking is no longer active. Therefore we need not
1304 // re-enable reference discovery for the CM ref processor.
1305 // That will be done at the start of the next marking cycle.
1306 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1307 ref_processor_cm()->verify_no_references_recorded();
1308
1309 reset_gc_time_stamp();
1310 // Since everything potentially moved, we will clear all remembered
1311 // sets, and clear all cards. Later we will rebuild remembered
1312 // sets. We will also reset the GC time stamps of the regions.
1313 clear_rsets_post_compaction();
1314 check_gc_time_stamps();
1315
1316 resize_if_necessary_after_full_collection();
1317
1318 // We should do this after we potentially resize the heap so
1319 // that all the COMMIT / UNCOMMIT events are generated before
1320 // the compaction events.
1321 print_hrm_post_compaction();
1322
1323 if (_hot_card_cache->use_cache()) {
1324 _hot_card_cache->reset_card_counts();
1325 _hot_card_cache->reset_hot_cache();
1326 }
1327
1328 // Rebuild remembered sets of all regions.
1329 uint n_workers =
1330 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1331 workers()->active_workers(),
1332 Threads::number_of_non_daemon_threads());
1333 workers()->update_active_workers(n_workers);
1334 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1335
1336 ParRebuildRSTask rebuild_rs_task(this);
1337 workers()->run_task(&rebuild_rs_task);
1338
1339 // Rebuild the strong code root lists for each region
1340 rebuild_strong_code_roots();
1341
1342 if (true) { // FIXME
1343 MetaspaceGC::compute_new_size();
1344 }
1345
1346 #ifdef TRACESPINNING
1347 ParallelTaskTerminator::print_termination_counts();
1348 #endif
1349
1350 // Discard all rset updates
1351 JavaThread::dirty_card_queue_set().abandon_logs();
1352 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1353
1354 // At this point there should be no regions in the
1355 // entire heap tagged as young.
1356 assert(check_young_list_empty(), "young list should be empty at this point");
1357
1358 // Update the number of full collections that have been completed.
1359 increment_old_marking_cycles_completed(false /* concurrent */);
1360
1361 _hrm.verify_optional();
1362 _verifier->verify_region_sets_optional();
1363
1364 _verifier->verify_after_gc();
1365
1366 // Clear the previous marking bitmap, if needed for bitmap verification.
1367 // Note we cannot do this when we clear the next marking bitmap in
1368 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1369 // objects marked during a full GC against the previous bitmap.
1370 // But we need to clear it before calling check_bitmaps below since
1371 // the full GC has compacted objects and updated TAMS but not updated
1372 // the prev bitmap.
1373 if (G1VerifyBitmaps) {
1374 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1375 _cm->clear_prev_bitmap(workers());
1376 }
1377 _verifier->check_bitmaps("Full GC End");
1378
1379 start_new_collection_set();
1380
1381 _allocator->init_mutator_alloc_region();
1382
1383 g1_policy()->record_full_collection_end();
1384
1385 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1386 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1387 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1388 // before any GC notifications are raised.
1389 g1mm()->update_sizes();
1390
1391 gc_epilogue(true);
1392
1393 heap_transition.print();
1394
1395 print_heap_after_gc();
1396 print_heap_regions();
1397 trace_heap_after_gc(gc_tracer);
1398
1399 post_full_gc_dump(gc_timer);
1400 }
1401
1402 gc_timer->register_gc_end();
1403 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1404 }
1405
1406 return true;
1407 }
1408
1409 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1410 // Currently, there is no facility in the do_full_collection(bool) API to notify
1411 // the caller that the collection did not succeed (e.g., because it was locked
1412 // out by the GC locker). So, right now, we'll ignore the return value.
1413 bool dummy = do_full_collection(true, /* explicit_gc */
1414 clear_all_soft_refs);
1415 }
1416
1417 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1418 // Include bytes that will be pre-allocated to support collections, as "used".
1419 const size_t used_after_gc = used();
1420 const size_t capacity_after_gc = capacity();
1421 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1422
1423 // This is enforced in arguments.cpp.
1424 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1425 "otherwise the code below doesn't make sense");
1426
1427 // We don't have floating point command-line arguments
1428 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1429 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1430 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1431 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1432
1433 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1434 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1435
1436 // We have to be careful here as these two calculations can overflow
1437 // 32-bit size_t's.
1438 double used_after_gc_d = (double) used_after_gc;
1439 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1440 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1441
1442 // Let's make sure that they are both under the max heap size, which
1443 // by default will make them fit into a size_t.
1444 double desired_capacity_upper_bound = (double) max_heap_size;
1445 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1446 desired_capacity_upper_bound);
1447 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1448 desired_capacity_upper_bound);
1449
1450 // We can now safely turn them into size_t's.
1451 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1452 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1453
1454 // This assert only makes sense here, before we adjust them
1455 // with respect to the min and max heap size.
1456 assert(minimum_desired_capacity <= maximum_desired_capacity,
1457 "minimum_desired_capacity = " SIZE_FORMAT ", "
1458 "maximum_desired_capacity = " SIZE_FORMAT,
1459 minimum_desired_capacity, maximum_desired_capacity);
1460
1461 // Should not be greater than the heap max size. No need to adjust
1462 // it with respect to the heap min size as it's a lower bound (i.e.,
1463 // we'll try to make the capacity larger than it, not smaller).
1464 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1465 // Should not be less than the heap min size. No need to adjust it
1466 // with respect to the heap max size as it's an upper bound (i.e.,
1467 // we'll try to make the capacity smaller than it, not greater).
1468 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1469
1470 if (capacity_after_gc < minimum_desired_capacity) {
1471 // Don't expand unless it's significant
1472 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1473
1474 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1475 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1476 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1477
1478 expand(expand_bytes, _workers);
1479
1480 // No expansion, now see if we want to shrink
1481 } else if (capacity_after_gc > maximum_desired_capacity) {
1482 // Capacity too large, compute shrinking size
1483 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1484
1485 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1486 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1487 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1488
1489 shrink(shrink_bytes);
1490 }
1491 }
1492
1493 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1494 AllocationContext_t context,
1495 bool do_gc,
1496 bool clear_all_soft_refs,
1497 bool expect_null_mutator_alloc_region,
1498 bool* gc_succeeded) {
1499 *gc_succeeded = true;
1500 // Let's attempt the allocation first.
1501 HeapWord* result =
1502 attempt_allocation_at_safepoint(word_size,
1503 context,
1504 expect_null_mutator_alloc_region);
1505 if (result != NULL) {
1506 assert(*gc_succeeded, "sanity");
1507 return result;
1508 }
1509
1510 // In a G1 heap, we're supposed to keep allocation from failing by
1511 // incremental pauses. Therefore, at least for now, we'll favor
1512 // expansion over collection. (This might change in the future if we can
1513 // do something smarter than full collection to satisfy a failed alloc.)
1514 result = expand_and_allocate(word_size, context);
1515 if (result != NULL) {
1516 assert(*gc_succeeded, "sanity");
1517 return result;
1518 }
1519
1520 if (do_gc) {
1521 // Expansion didn't work, we'll try to do a Full GC.
1522 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1523 clear_all_soft_refs);
1524 }
1525
1526 return NULL;
1527 }
1528
1529 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1530 AllocationContext_t context,
1531 bool* succeeded) {
1532 assert_at_safepoint(true /* should_be_vm_thread */);
1533
1534 // Attempts to allocate followed by Full GC.
1535 HeapWord* result =
1536 satisfy_failed_allocation_helper(word_size,
1537 context,
1538 true, /* do_gc */
1539 false, /* clear_all_soft_refs */
1540 false, /* expect_null_mutator_alloc_region */
1541 succeeded);
1542
1543 if (result != NULL || !*succeeded) {
1544 return result;
1545 }
1546
1547 // Attempts to allocate followed by Full GC that will collect all soft references.
1548 result = satisfy_failed_allocation_helper(word_size,
1549 context,
1550 true, /* do_gc */
1551 true, /* clear_all_soft_refs */
1552 true, /* expect_null_mutator_alloc_region */
1553 succeeded);
1554
1555 if (result != NULL || !*succeeded) {
1556 return result;
1557 }
1558
1559 // Attempts to allocate, no GC
1560 result = satisfy_failed_allocation_helper(word_size,
1561 context,
1562 false, /* do_gc */
1563 false, /* clear_all_soft_refs */
1564 true, /* expect_null_mutator_alloc_region */
1565 succeeded);
1566
1567 if (result != NULL) {
1568 assert(*succeeded, "sanity");
1569 return result;
1570 }
1571
1572 assert(!collector_policy()->should_clear_all_soft_refs(),
1573 "Flag should have been handled and cleared prior to this point");
1574
1575 // What else? We might try synchronous finalization later. If the total
1576 // space available is large enough for the allocation, then a more
1577 // complete compaction phase than we've tried so far might be
1578 // appropriate.
1579 assert(*succeeded, "sanity");
1580 return NULL;
1581 }
1582
1583 // Attempting to expand the heap sufficiently
1584 // to support an allocation of the given "word_size". If
1585 // successful, perform the allocation and return the address of the
1586 // allocated block, or else "NULL".
1587
1588 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1589 assert_at_safepoint(true /* should_be_vm_thread */);
1590
1591 _verifier->verify_region_sets_optional();
1592
1593 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1594 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1595 word_size * HeapWordSize);
1596
1597
1598 if (expand(expand_bytes, _workers)) {
1599 _hrm.verify_optional();
1600 _verifier->verify_region_sets_optional();
1601 return attempt_allocation_at_safepoint(word_size,
1602 context,
1603 false /* expect_null_mutator_alloc_region */);
1604 }
1605 return NULL;
1606 }
1607
1608 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1609 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1610 aligned_expand_bytes = align_up(aligned_expand_bytes,
1611 HeapRegion::GrainBytes);
1612
1613 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1614 expand_bytes, aligned_expand_bytes);
1615
1616 if (is_maximal_no_gc()) {
1617 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1618 return false;
1619 }
1620
1621 double expand_heap_start_time_sec = os::elapsedTime();
1622 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1623 assert(regions_to_expand > 0, "Must expand by at least one region");
1624
1625 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1626 if (expand_time_ms != NULL) {
1627 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1628 }
1629
1630 if (expanded_by > 0) {
1631 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1632 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1633 g1_policy()->record_new_heap_size(num_regions());
1634 } else {
1635 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1636
1637 // The expansion of the virtual storage space was unsuccessful.
1638 // Let's see if it was because we ran out of swap.
1639 if (G1ExitOnExpansionFailure &&
1640 _hrm.available() >= regions_to_expand) {
1641 // We had head room...
1642 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1643 }
1644 }
1645 return regions_to_expand > 0;
1646 }
1647
1648 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1649 size_t aligned_shrink_bytes =
1650 ReservedSpace::page_align_size_down(shrink_bytes);
1651 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1652 HeapRegion::GrainBytes);
1653 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1654
1655 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1656 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1657
1658
1659 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",
1660 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1661 if (num_regions_removed > 0) {
1662 g1_policy()->record_new_heap_size(num_regions());
1663 } else {
1664 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1665 }
1666 }
1667
1668 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1669 _verifier->verify_region_sets_optional();
1670
1671 // We should only reach here at the end of a Full GC which means we
1672 // should not not be holding to any GC alloc regions. The method
1673 // below will make sure of that and do any remaining clean up.
1674 _allocator->abandon_gc_alloc_regions();
1675
1676 // Instead of tearing down / rebuilding the free lists here, we
1677 // could instead use the remove_all_pending() method on free_list to
1678 // remove only the ones that we need to remove.
1679 tear_down_region_sets(true /* free_list_only */);
1680 shrink_helper(shrink_bytes);
1681 rebuild_region_sets(true /* free_list_only */);
1682
1683 _hrm.verify_optional();
1684 _verifier->verify_region_sets_optional();
1685 }
1686
1687 // Public methods.
1688
1689 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1690 CollectedHeap(),
1691 _collector_policy(collector_policy),
1692 _g1_policy(create_g1_policy()),
1693 _collection_set(this, _g1_policy),
1694 _dirty_card_queue_set(false),
1695 _is_alive_closure_cm(this),
1696 _is_alive_closure_stw(this),
1697 _ref_processor_cm(NULL),
1698 _ref_processor_stw(NULL),
1699 _bot(NULL),
1700 _hot_card_cache(NULL),
1701 _g1_rem_set(NULL),
1702 _cg1r(NULL),
1703 _g1mm(NULL),
1704 _refine_cte_cl(NULL),
1705 _preserved_marks_set(true /* in_c_heap */),
1706 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1707 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1708 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1709 _humongous_reclaim_candidates(),
1710 _has_humongous_reclaim_candidates(false),
1711 _archive_allocator(NULL),
1712 _free_regions_coming(false),
1713 _gc_time_stamp(0),
1714 _summary_bytes_used(0),
1715 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1716 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1717 _expand_heap_after_alloc_failure(true),
1718 _old_marking_cycles_started(0),
1719 _old_marking_cycles_completed(0),
1720 _in_cset_fast_test(),
1721 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1722 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1723
1724 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1725 /* are_GC_task_threads */true,
1726 /* are_ConcurrentGC_threads */false);
1727 _workers->initialize_workers();
1728 _verifier = new G1HeapVerifier(this);
1729
1730 _allocator = G1Allocator::create_allocator(this);
1731
1732 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1733
1734 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1735
1736 // Override the default _filler_array_max_size so that no humongous filler
1737 // objects are created.
1738 _filler_array_max_size = _humongous_object_threshold_in_words;
1739
1740 uint n_queues = ParallelGCThreads;
1741 _task_queues = new RefToScanQueueSet(n_queues);
1742
1743 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1744
1745 for (uint i = 0; i < n_queues; i++) {
1746 RefToScanQueue* q = new RefToScanQueue();
1747 q->initialize();
1748 _task_queues->register_queue(i, q);
1749 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1750 }
1751
1752 // Initialize the G1EvacuationFailureALot counters and flags.
1753 NOT_PRODUCT(reset_evacuation_should_fail();)
1754
1755 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1756 }
1757
1758 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1759 size_t size,
1760 size_t translation_factor) {
1761 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1762 // Allocate a new reserved space, preferring to use large pages.
1763 ReservedSpace rs(size, preferred_page_size);
1764 G1RegionToSpaceMapper* result =
1765 G1RegionToSpaceMapper::create_mapper(rs,
1766 size,
1767 rs.alignment(),
1768 HeapRegion::GrainBytes,
1769 translation_factor,
1770 mtGC);
1771
1772 os::trace_page_sizes_for_requested_size(description,
1773 size,
1774 preferred_page_size,
1775 rs.alignment(),
1776 rs.base(),
1777 rs.size());
1778
1779 return result;
1780 }
1781
1782 jint G1CollectedHeap::initialize() {
1783 CollectedHeap::pre_initialize();
1784 os::enable_vtime();
1785
1786 // Necessary to satisfy locking discipline assertions.
1787
1788 MutexLocker x(Heap_lock);
1789
1790 // While there are no constraints in the GC code that HeapWordSize
1791 // be any particular value, there are multiple other areas in the
1792 // system which believe this to be true (e.g. oop->object_size in some
1793 // cases incorrectly returns the size in wordSize units rather than
1794 // HeapWordSize).
1795 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1796
1797 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1798 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1799 size_t heap_alignment = collector_policy()->heap_alignment();
1800
1801 // Ensure that the sizes are properly aligned.
1802 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1803 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1804 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1805
1806 _refine_cte_cl = new RefineCardTableEntryClosure();
1807
1808 jint ecode = JNI_OK;
1809 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1810 if (_cg1r == NULL) {
1811 return ecode;
1812 }
1813
1814 // Reserve the maximum.
1815
1816 // When compressed oops are enabled, the preferred heap base
1817 // is calculated by subtracting the requested size from the
1818 // 32Gb boundary and using the result as the base address for
1819 // heap reservation. If the requested size is not aligned to
1820 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1821 // into the ReservedHeapSpace constructor) then the actual
1822 // base of the reserved heap may end up differing from the
1823 // address that was requested (i.e. the preferred heap base).
1824 // If this happens then we could end up using a non-optimal
1825 // compressed oops mode.
1826
1827 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1828 heap_alignment);
1829
1830 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1831
1832 // Create the barrier set for the entire reserved region.
1833 G1SATBCardTableLoggingModRefBS* bs
1834 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1835 bs->initialize();
1836 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1837 set_barrier_set(bs);
1838
1839 // Create the hot card cache.
1840 _hot_card_cache = new G1HotCardCache(this);
1841
1842 // Also create a G1 rem set.
1843 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1844
1845 // Carve out the G1 part of the heap.
1846 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1847 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1848 G1RegionToSpaceMapper* heap_storage =
1849 G1RegionToSpaceMapper::create_mapper(g1_rs,
1850 g1_rs.size(),
1851 page_size,
1852 HeapRegion::GrainBytes,
1853 1,
1854 mtJavaHeap);
1855 os::trace_page_sizes("Heap",
1856 collector_policy()->min_heap_byte_size(),
1857 max_byte_size,
1858 page_size,
1859 heap_rs.base(),
1860 heap_rs.size());
1861 heap_storage->set_mapping_changed_listener(&_listener);
1862
1863 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1864 G1RegionToSpaceMapper* bot_storage =
1865 create_aux_memory_mapper("Block Offset Table",
1866 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1867 G1BlockOffsetTable::heap_map_factor());
1868
1869 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1870 G1RegionToSpaceMapper* cardtable_storage =
1871 create_aux_memory_mapper("Card Table",
1872 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1873 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1874
1875 G1RegionToSpaceMapper* card_counts_storage =
1876 create_aux_memory_mapper("Card Counts Table",
1877 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1878 G1CardCounts::heap_map_factor());
1879
1880 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1881 G1RegionToSpaceMapper* prev_bitmap_storage =
1882 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1883 G1RegionToSpaceMapper* next_bitmap_storage =
1884 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1885
1886 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1887 g1_barrier_set()->initialize(cardtable_storage);
1888 // Do later initialization work for concurrent refinement.
1889 _hot_card_cache->initialize(card_counts_storage);
1890
1891 // 6843694 - ensure that the maximum region index can fit
1892 // in the remembered set structures.
1893 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1894 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1895
1896 g1_rem_set()->initialize(max_capacity(), max_regions());
1897
1898 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1899 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1900 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1901 "too many cards per region");
1902
1903 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1904
1905 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1906
1907 {
1908 HeapWord* start = _hrm.reserved().start();
1909 HeapWord* end = _hrm.reserved().end();
1910 size_t granularity = HeapRegion::GrainBytes;
1911
1912 _in_cset_fast_test.initialize(start, end, granularity);
1913 _humongous_reclaim_candidates.initialize(start, end, granularity);
1914 }
1915
1916 // Create the G1ConcurrentMark data structure and thread.
1917 // (Must do this late, so that "max_regions" is defined.)
1918 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1919 if (_cm == NULL || !_cm->completed_initialization()) {
1920 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1921 return JNI_ENOMEM;
1922 }
1923 _cmThread = _cm->cmThread();
1924
1925 // Now expand into the initial heap size.
1926 if (!expand(init_byte_size, _workers)) {
1927 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1928 return JNI_ENOMEM;
1929 }
1930
1931 // Perform any initialization actions delegated to the policy.
1932 g1_policy()->init(this, &_collection_set);
1933
1934 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1935 SATB_Q_FL_lock,
1936 G1SATBProcessCompletedThreshold,
1937 Shared_SATB_Q_lock);
1938
1939 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1940 DirtyCardQ_CBL_mon,
1941 DirtyCardQ_FL_lock,
1942 (int)concurrent_g1_refine()->yellow_zone(),
1943 (int)concurrent_g1_refine()->red_zone(),
1944 Shared_DirtyCardQ_lock,
1945 NULL, // fl_owner
1946 true); // init_free_ids
1947
1948 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1949 DirtyCardQ_CBL_mon,
1950 DirtyCardQ_FL_lock,
1951 -1, // never trigger processing
1952 -1, // no limit on length
1953 Shared_DirtyCardQ_lock,
1954 &JavaThread::dirty_card_queue_set());
1955
1956 // Here we allocate the dummy HeapRegion that is required by the
1957 // G1AllocRegion class.
1958 HeapRegion* dummy_region = _hrm.get_dummy_region();
1959
1960 // We'll re-use the same region whether the alloc region will
1961 // require BOT updates or not and, if it doesn't, then a non-young
1962 // region will complain that it cannot support allocations without
1963 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1964 dummy_region->set_eden();
1965 // Make sure it's full.
1966 dummy_region->set_top(dummy_region->end());
1967 G1AllocRegion::setup(this, dummy_region);
1968
1969 _allocator->init_mutator_alloc_region();
1970
1971 // Do create of the monitoring and management support so that
1972 // values in the heap have been properly initialized.
1973 _g1mm = new G1MonitoringSupport(this);
1974
1975 G1StringDedup::initialize();
1976
1977 _preserved_marks_set.init(ParallelGCThreads);
1978
1979 _collection_set.initialize(max_regions());
1980
1981 return JNI_OK;
1982 }
1983
1984 void G1CollectedHeap::stop() {
1985 // Stop all concurrent threads. We do this to make sure these threads
1986 // do not continue to execute and access resources (e.g. logging)
1987 // that are destroyed during shutdown.
1988 _cg1r->stop();
1989 _cmThread->stop();
1990 if (G1StringDedup::is_enabled()) {
1991 G1StringDedup::stop();
1992 }
1993 }
1994
1995 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1996 return HeapRegion::max_region_size();
1997 }
1998
1999 void G1CollectedHeap::post_initialize() {
2000 ref_processing_init();
2001 }
2002
2003 void G1CollectedHeap::ref_processing_init() {
2004 // Reference processing in G1 currently works as follows:
2005 //
2006 // * There are two reference processor instances. One is
2007 // used to record and process discovered references
2008 // during concurrent marking; the other is used to
2009 // record and process references during STW pauses
2010 // (both full and incremental).
2011 // * Both ref processors need to 'span' the entire heap as
2012 // the regions in the collection set may be dotted around.
2013 //
2014 // * For the concurrent marking ref processor:
2015 // * Reference discovery is enabled at initial marking.
2016 // * Reference discovery is disabled and the discovered
2017 // references processed etc during remarking.
2018 // * Reference discovery is MT (see below).
2019 // * Reference discovery requires a barrier (see below).
2020 // * Reference processing may or may not be MT
2021 // (depending on the value of ParallelRefProcEnabled
2022 // and ParallelGCThreads).
2023 // * A full GC disables reference discovery by the CM
2024 // ref processor and abandons any entries on it's
2025 // discovered lists.
2026 //
2027 // * For the STW processor:
2028 // * Non MT discovery is enabled at the start of a full GC.
2029 // * Processing and enqueueing during a full GC is non-MT.
2030 // * During a full GC, references are processed after marking.
2031 //
2032 // * Discovery (may or may not be MT) is enabled at the start
2033 // of an incremental evacuation pause.
2034 // * References are processed near the end of a STW evacuation pause.
2035 // * For both types of GC:
2036 // * Discovery is atomic - i.e. not concurrent.
2037 // * Reference discovery will not need a barrier.
2038
2039 MemRegion mr = reserved_region();
2040
2041 // Concurrent Mark ref processor
2042 _ref_processor_cm =
2043 new ReferenceProcessor(mr, // span
2044 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2045 // mt processing
2046 ParallelGCThreads,
2047 // degree of mt processing
2048 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2049 // mt discovery
2050 MAX2(ParallelGCThreads, ConcGCThreads),
2051 // degree of mt discovery
2052 false,
2053 // Reference discovery is not atomic
2054 &_is_alive_closure_cm);
2055 // is alive closure
2056 // (for efficiency/performance)
2057
2058 // STW ref processor
2059 _ref_processor_stw =
2060 new ReferenceProcessor(mr, // span
2061 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2062 // mt processing
2063 ParallelGCThreads,
2064 // degree of mt processing
2065 (ParallelGCThreads > 1),
2066 // mt discovery
2067 ParallelGCThreads,
2068 // degree of mt discovery
2069 true,
2070 // Reference discovery is atomic
2071 &_is_alive_closure_stw);
2072 // is alive closure
2073 // (for efficiency/performance)
2074 }
2075
2076 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2077 return _collector_policy;
2078 }
2079
2080 size_t G1CollectedHeap::capacity() const {
2081 return _hrm.length() * HeapRegion::GrainBytes;
2082 }
2083
2084 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2085 hr->reset_gc_time_stamp();
2086 }
2087
2088 #ifndef PRODUCT
2089
2090 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2091 private:
2092 unsigned _gc_time_stamp;
2093 bool _failures;
2094
2095 public:
2096 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2097 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2098
2099 virtual bool doHeapRegion(HeapRegion* hr) {
2100 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2101 if (_gc_time_stamp != region_gc_time_stamp) {
2102 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2103 region_gc_time_stamp, _gc_time_stamp);
2104 _failures = true;
2105 }
2106 return false;
2107 }
2108
2109 bool failures() { return _failures; }
2110 };
2111
2112 void G1CollectedHeap::check_gc_time_stamps() {
2113 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2114 heap_region_iterate(&cl);
2115 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2116 }
2117 #endif // PRODUCT
2118
2119 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2120 _hot_card_cache->drain(cl, worker_i);
2121 }
2122
2123 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2124 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2125 size_t n_completed_buffers = 0;
2126 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2127 n_completed_buffers++;
2128 }
2129 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2130 dcqs.clear_n_completed_buffers();
2131 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2132 }
2133
2134 // Computes the sum of the storage used by the various regions.
2135 size_t G1CollectedHeap::used() const {
2136 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2137 if (_archive_allocator != NULL) {
2138 result += _archive_allocator->used();
2139 }
2140 return result;
2141 }
2142
2143 size_t G1CollectedHeap::used_unlocked() const {
2144 return _summary_bytes_used;
2145 }
2146
2147 class SumUsedClosure: public HeapRegionClosure {
2148 size_t _used;
2149 public:
2150 SumUsedClosure() : _used(0) {}
2151 bool doHeapRegion(HeapRegion* r) {
2152 _used += r->used();
2153 return false;
2154 }
2155 size_t result() { return _used; }
2156 };
2157
2158 size_t G1CollectedHeap::recalculate_used() const {
2159 double recalculate_used_start = os::elapsedTime();
2160
2161 SumUsedClosure blk;
2162 heap_region_iterate(&blk);
2163
2164 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2165 return blk.result();
2166 }
2167
2168 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2169 switch (cause) {
2170 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2171 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2172 case GCCause::_update_allocation_context_stats_inc: return true;
2173 case GCCause::_wb_conc_mark: return true;
2174 default : return false;
2175 }
2176 }
2177
2178 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2179 switch (cause) {
2180 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2181 case GCCause::_g1_humongous_allocation: return true;
2182 default: return is_user_requested_concurrent_full_gc(cause);
2183 }
2184 }
2185
2186 #ifndef PRODUCT
2187 void G1CollectedHeap::allocate_dummy_regions() {
2188 // Let's fill up most of the region
2189 size_t word_size = HeapRegion::GrainWords - 1024;
2190 // And as a result the region we'll allocate will be humongous.
2191 guarantee(is_humongous(word_size), "sanity");
2192
2193 // _filler_array_max_size is set to humongous object threshold
2194 // but temporarily change it to use CollectedHeap::fill_with_object().
2195 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2196
2197 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2198 // Let's use the existing mechanism for the allocation
2199 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2200 AllocationContext::system());
2201 if (dummy_obj != NULL) {
2202 MemRegion mr(dummy_obj, word_size);
2203 CollectedHeap::fill_with_object(mr);
2204 } else {
2205 // If we can't allocate once, we probably cannot allocate
2206 // again. Let's get out of the loop.
2207 break;
2208 }
2209 }
2210 }
2211 #endif // !PRODUCT
2212
2213 void G1CollectedHeap::increment_old_marking_cycles_started() {
2214 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2215 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2216 "Wrong marking cycle count (started: %d, completed: %d)",
2217 _old_marking_cycles_started, _old_marking_cycles_completed);
2218
2219 _old_marking_cycles_started++;
2220 }
2221
2222 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2223 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2224
2225 // We assume that if concurrent == true, then the caller is a
2226 // concurrent thread that was joined the Suspendible Thread
2227 // Set. If there's ever a cheap way to check this, we should add an
2228 // assert here.
2229
2230 // Given that this method is called at the end of a Full GC or of a
2231 // concurrent cycle, and those can be nested (i.e., a Full GC can
2232 // interrupt a concurrent cycle), the number of full collections
2233 // completed should be either one (in the case where there was no
2234 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2235 // behind the number of full collections started.
2236
2237 // This is the case for the inner caller, i.e. a Full GC.
2238 assert(concurrent ||
2239 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2240 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2241 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2242 "is inconsistent with _old_marking_cycles_completed = %u",
2243 _old_marking_cycles_started, _old_marking_cycles_completed);
2244
2245 // This is the case for the outer caller, i.e. the concurrent cycle.
2246 assert(!concurrent ||
2247 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2248 "for outer caller (concurrent cycle): "
2249 "_old_marking_cycles_started = %u "
2250 "is inconsistent with _old_marking_cycles_completed = %u",
2251 _old_marking_cycles_started, _old_marking_cycles_completed);
2252
2253 _old_marking_cycles_completed += 1;
2254
2255 // We need to clear the "in_progress" flag in the CM thread before
2256 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2257 // is set) so that if a waiter requests another System.gc() it doesn't
2258 // incorrectly see that a marking cycle is still in progress.
2259 if (concurrent) {
2260 _cmThread->set_idle();
2261 }
2262
2263 // This notify_all() will ensure that a thread that called
2264 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2265 // and it's waiting for a full GC to finish will be woken up. It is
2266 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2267 FullGCCount_lock->notify_all();
2268 }
2269
2270 void G1CollectedHeap::collect(GCCause::Cause cause) {
2271 assert_heap_not_locked();
2272
2273 uint gc_count_before;
2274 uint old_marking_count_before;
2275 uint full_gc_count_before;
2276 bool retry_gc;
2277
2278 do {
2279 retry_gc = false;
2280
2281 {
2282 MutexLocker ml(Heap_lock);
2283
2284 // Read the GC count while holding the Heap_lock
2285 gc_count_before = total_collections();
2286 full_gc_count_before = total_full_collections();
2287 old_marking_count_before = _old_marking_cycles_started;
2288 }
2289
2290 if (should_do_concurrent_full_gc(cause)) {
2291 // Schedule an initial-mark evacuation pause that will start a
2292 // concurrent cycle. We're setting word_size to 0 which means that
2293 // we are not requesting a post-GC allocation.
2294 VM_G1IncCollectionPause op(gc_count_before,
2295 0, /* word_size */
2296 true, /* should_initiate_conc_mark */
2297 g1_policy()->max_pause_time_ms(),
2298 cause);
2299 op.set_allocation_context(AllocationContext::current());
2300
2301 VMThread::execute(&op);
2302 if (!op.pause_succeeded()) {
2303 if (old_marking_count_before == _old_marking_cycles_started) {
2304 retry_gc = op.should_retry_gc();
2305 } else {
2306 // A Full GC happened while we were trying to schedule the
2307 // initial-mark GC. No point in starting a new cycle given
2308 // that the whole heap was collected anyway.
2309 }
2310
2311 if (retry_gc) {
2312 if (GCLocker::is_active_and_needs_gc()) {
2313 GCLocker::stall_until_clear();
2314 }
2315 }
2316 }
2317 } else {
2318 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2319 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2320
2321 // Schedule a standard evacuation pause. We're setting word_size
2322 // to 0 which means that we are not requesting a post-GC allocation.
2323 VM_G1IncCollectionPause op(gc_count_before,
2324 0, /* word_size */
2325 false, /* should_initiate_conc_mark */
2326 g1_policy()->max_pause_time_ms(),
2327 cause);
2328 VMThread::execute(&op);
2329 } else {
2330 // Schedule a Full GC.
2331 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2332 VMThread::execute(&op);
2333 }
2334 }
2335 } while (retry_gc);
2336 }
2337
2338 bool G1CollectedHeap::is_in(const void* p) const {
2339 if (_hrm.reserved().contains(p)) {
2340 // Given that we know that p is in the reserved space,
2341 // heap_region_containing() should successfully
2342 // return the containing region.
2343 HeapRegion* hr = heap_region_containing(p);
2344 return hr->is_in(p);
2345 } else {
2346 return false;
2347 }
2348 }
2349
2350 #ifdef ASSERT
2351 bool G1CollectedHeap::is_in_exact(const void* p) const {
2352 bool contains = reserved_region().contains(p);
2353 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2354 if (contains && available) {
2355 return true;
2356 } else {
2357 return false;
2358 }
2359 }
2360 #endif
2361
2362 // Iteration functions.
2363
2364 // Iterates an ObjectClosure over all objects within a HeapRegion.
2365
2366 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2367 ObjectClosure* _cl;
2368 public:
2369 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2370 bool doHeapRegion(HeapRegion* r) {
2371 if (!r->is_continues_humongous()) {
2372 r->object_iterate(_cl);
2373 }
2374 return false;
2375 }
2376 };
2377
2378 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2379 IterateObjectClosureRegionClosure blk(cl);
2380 heap_region_iterate(&blk);
2381 }
2382
2383 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2384 _hrm.iterate(cl);
2385 }
2386
2387 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2388 uint worker_id,
2389 HeapRegionClaimer *hrclaimer) const {
2390 _hrm.par_iterate(cl, worker_id, hrclaimer);
2391 }
2392
2393 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2394 _collection_set.iterate(cl);
2395 }
2396
2397 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2398 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2399 }
2400
2401 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2402 HeapRegion* result = _hrm.next_region_in_heap(from);
2403 while (result != NULL && result->is_pinned()) {
2404 result = _hrm.next_region_in_heap(result);
2405 }
2406 return result;
2407 }
2408
2409 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2410 HeapRegion* hr = heap_region_containing(addr);
2411 return hr->block_start(addr);
2412 }
2413
2414 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2415 HeapRegion* hr = heap_region_containing(addr);
2416 return hr->block_size(addr);
2417 }
2418
2419 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2420 HeapRegion* hr = heap_region_containing(addr);
2421 return hr->block_is_obj(addr);
2422 }
2423
2424 bool G1CollectedHeap::supports_tlab_allocation() const {
2425 return true;
2426 }
2427
2428 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2429 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2430 }
2431
2432 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2433 return _eden.length() * HeapRegion::GrainBytes;
2434 }
2435
2436 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2437 // must be equal to the humongous object limit.
2438 size_t G1CollectedHeap::max_tlab_size() const {
2439 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2440 }
2441
2442 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2443 AllocationContext_t context = AllocationContext::current();
2444 return _allocator->unsafe_max_tlab_alloc(context);
2445 }
2446
2447 size_t G1CollectedHeap::max_capacity() const {
2448 return _hrm.reserved().byte_size();
2449 }
2450
2451 jlong G1CollectedHeap::millis_since_last_gc() {
2452 // See the notes in GenCollectedHeap::millis_since_last_gc()
2453 // for more information about the implementation.
2454 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2455 _g1_policy->collection_pause_end_millis();
2456 if (ret_val < 0) {
2457 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2458 ". returning zero instead.", ret_val);
2459 return 0;
2460 }
2461 return ret_val;
2462 }
2463
2464 void G1CollectedHeap::prepare_for_verify() {
2465 _verifier->prepare_for_verify();
2466 }
2467
2468 void G1CollectedHeap::verify(VerifyOption vo) {
2469 _verifier->verify(vo);
2470 }
2471
2472 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2473 return true;
2474 }
2475
2476 const char* const* G1CollectedHeap::concurrent_phases() const {
2477 return _cmThread->concurrent_phases();
2478 }
2479
2480 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2481 return _cmThread->request_concurrent_phase(phase);
2482 }
2483
2484 class PrintRegionClosure: public HeapRegionClosure {
2485 outputStream* _st;
2486 public:
2487 PrintRegionClosure(outputStream* st) : _st(st) {}
2488 bool doHeapRegion(HeapRegion* r) {
2489 r->print_on(_st);
2490 return false;
2491 }
2492 };
2493
2494 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2495 const HeapRegion* hr,
2496 const VerifyOption vo) const {
2497 switch (vo) {
2498 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2499 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2500 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2501 default: ShouldNotReachHere();
2502 }
2503 return false; // keep some compilers happy
2504 }
2505
2506 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2507 const VerifyOption vo) const {
2508 switch (vo) {
2509 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2510 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2511 case VerifyOption_G1UseMarkWord: {
2512 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2513 return !obj->is_gc_marked() && !hr->is_archive();
2514 }
2515 default: ShouldNotReachHere();
2516 }
2517 return false; // keep some compilers happy
2518 }
2519
2520 void G1CollectedHeap::print_heap_regions() const {
2521 Log(gc, heap, region) log;
2522 if (log.is_trace()) {
2523 ResourceMark rm;
2524 print_regions_on(log.trace_stream());
2525 }
2526 }
2527
2528 void G1CollectedHeap::print_on(outputStream* st) const {
2529 st->print(" %-20s", "garbage-first heap");
2530 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2531 capacity()/K, used_unlocked()/K);
2532 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2533 p2i(_hrm.reserved().start()),
2534 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2535 p2i(_hrm.reserved().end()));
2536 st->cr();
2537 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2538 uint young_regions = young_regions_count();
2539 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2540 (size_t) young_regions * HeapRegion::GrainBytes / K);
2541 uint survivor_regions = survivor_regions_count();
2542 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2543 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2544 st->cr();
2545 MetaspaceAux::print_on(st);
2546 }
2547
2548 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2549 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2550 "HS=humongous(starts), HC=humongous(continues), "
2551 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2552 "AC=allocation context, "
2553 "TAMS=top-at-mark-start (previous, next)");
2554 PrintRegionClosure blk(st);
2555 heap_region_iterate(&blk);
2556 }
2557
2558 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2559 print_on(st);
2560
2561 // Print the per-region information.
2562 print_regions_on(st);
2563 }
2564
2565 void G1CollectedHeap::print_on_error(outputStream* st) const {
2566 this->CollectedHeap::print_on_error(st);
2567
2568 if (_cm != NULL) {
2569 st->cr();
2570 _cm->print_on_error(st);
2571 }
2572 }
2573
2574 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2575 workers()->print_worker_threads_on(st);
2576 _cmThread->print_on(st);
2577 st->cr();
2578 _cm->print_worker_threads_on(st);
2579 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2580 if (G1StringDedup::is_enabled()) {
2581 G1StringDedup::print_worker_threads_on(st);
2582 }
2583 }
2584
2585 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2586 workers()->threads_do(tc);
2587 tc->do_thread(_cmThread);
2588 _cm->threads_do(tc);
2589 _cg1r->threads_do(tc); // also iterates over the sample thread
2590 if (G1StringDedup::is_enabled()) {
2591 G1StringDedup::threads_do(tc);
2592 }
2593 }
2594
2595 void G1CollectedHeap::print_tracing_info() const {
2596 g1_rem_set()->print_summary_info();
2597 concurrent_mark()->print_summary_info();
2598 }
2599
2600 #ifndef PRODUCT
2601 // Helpful for debugging RSet issues.
2602
2603 class PrintRSetsClosure : public HeapRegionClosure {
2604 private:
2605 const char* _msg;
2606 size_t _occupied_sum;
2607
2608 public:
2609 bool doHeapRegion(HeapRegion* r) {
2610 HeapRegionRemSet* hrrs = r->rem_set();
2611 size_t occupied = hrrs->occupied();
2612 _occupied_sum += occupied;
2613
2614 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2615 if (occupied == 0) {
2616 tty->print_cr(" RSet is empty");
2617 } else {
2618 hrrs->print();
2619 }
2620 tty->print_cr("----------");
2621 return false;
2622 }
2623
2624 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2625 tty->cr();
2626 tty->print_cr("========================================");
2627 tty->print_cr("%s", msg);
2628 tty->cr();
2629 }
2630
2631 ~PrintRSetsClosure() {
2632 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2633 tty->print_cr("========================================");
2634 tty->cr();
2635 }
2636 };
2637
2638 void G1CollectedHeap::print_cset_rsets() {
2639 PrintRSetsClosure cl("Printing CSet RSets");
2640 collection_set_iterate(&cl);
2641 }
2642
2643 void G1CollectedHeap::print_all_rsets() {
2644 PrintRSetsClosure cl("Printing All RSets");;
2645 heap_region_iterate(&cl);
2646 }
2647 #endif // PRODUCT
2648
2649 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2650
2651 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2652 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2653 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2654
2655 size_t eden_capacity_bytes =
2656 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2657
2658 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2659 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2660 eden_capacity_bytes, survivor_used_bytes, num_regions());
2661 }
2662
2663 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2664 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2665 stats->unused(), stats->used(), stats->region_end_waste(),
2666 stats->regions_filled(), stats->direct_allocated(),
2667 stats->failure_used(), stats->failure_waste());
2668 }
2669
2670 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2671 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2672 gc_tracer->report_gc_heap_summary(when, heap_summary);
2673
2674 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2675 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2676 }
2677
2678 G1CollectedHeap* G1CollectedHeap::heap() {
2679 CollectedHeap* heap = Universe::heap();
2680 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2681 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2682 return (G1CollectedHeap*)heap;
2683 }
2684
2685 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2686 // always_do_update_barrier = false;
2687 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2688
2689 double start = os::elapsedTime();
2690 // Fill TLAB's and such
2691 accumulate_statistics_all_tlabs();
2692 ensure_parsability(true);
2693 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2694
2695 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2696 }
2697
2698 void G1CollectedHeap::gc_epilogue(bool full) {
2699 // we are at the end of the GC. Total collections has already been increased.
2700 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2701
2702 // FIXME: what is this about?
2703 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2704 // is set.
2705 #if defined(COMPILER2) || INCLUDE_JVMCI
2706 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2707 #endif
2708 // always_do_update_barrier = true;
2709
2710 double start = os::elapsedTime();
2711 resize_all_tlabs();
2712 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2713
2714 allocation_context_stats().update(full);
2715
2716 // We have just completed a GC. Update the soft reference
2717 // policy with the new heap occupancy
2718 Universe::update_heap_info_at_gc();
2719 }
2720
2721 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2722 uint gc_count_before,
2723 bool* succeeded,
2724 GCCause::Cause gc_cause) {
2725 assert_heap_not_locked_and_not_at_safepoint();
2726 VM_G1IncCollectionPause op(gc_count_before,
2727 word_size,
2728 false, /* should_initiate_conc_mark */
2729 g1_policy()->max_pause_time_ms(),
2730 gc_cause);
2731
2732 op.set_allocation_context(AllocationContext::current());
2733 VMThread::execute(&op);
2734
2735 HeapWord* result = op.result();
2736 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2737 assert(result == NULL || ret_succeeded,
2738 "the result should be NULL if the VM did not succeed");
2739 *succeeded = ret_succeeded;
2740
2741 assert_heap_not_locked();
2742 return result;
2743 }
2744
2745 void
2746 G1CollectedHeap::doConcurrentMark() {
2747 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2748 if (!_cmThread->in_progress()) {
2749 _cmThread->set_started();
2750 CGC_lock->notify();
2751 }
2752 }
2753
2754 size_t G1CollectedHeap::pending_card_num() {
2755 size_t extra_cards = 0;
2756 JavaThread *curr = Threads::first();
2757 while (curr != NULL) {
2758 DirtyCardQueue& dcq = curr->dirty_card_queue();
2759 extra_cards += dcq.size();
2760 curr = curr->next();
2761 }
2762 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2763 size_t buffer_size = dcqs.buffer_size();
2764 size_t buffer_num = dcqs.completed_buffers_num();
2765
2766 return buffer_size * buffer_num + extra_cards;
2767 }
2768
2769 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2770 private:
2771 size_t _total_humongous;
2772 size_t _candidate_humongous;
2773
2774 DirtyCardQueue _dcq;
2775
2776 // We don't nominate objects with many remembered set entries, on
2777 // the assumption that such objects are likely still live.
2778 bool is_remset_small(HeapRegion* region) const {
2779 HeapRegionRemSet* const rset = region->rem_set();
2780 return G1EagerReclaimHumongousObjectsWithStaleRefs
2781 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2782 : rset->is_empty();
2783 }
2784
2785 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2786 assert(region->is_starts_humongous(), "Must start a humongous object");
2787
2788 oop obj = oop(region->bottom());
2789
2790 // Dead objects cannot be eager reclaim candidates. Due to class
2791 // unloading it is unsafe to query their classes so we return early.
2792 if (heap->is_obj_dead(obj, region)) {
2793 return false;
2794 }
2795
2796 // Candidate selection must satisfy the following constraints
2797 // while concurrent marking is in progress:
2798 //
2799 // * In order to maintain SATB invariants, an object must not be
2800 // reclaimed if it was allocated before the start of marking and
2801 // has not had its references scanned. Such an object must have
2802 // its references (including type metadata) scanned to ensure no
2803 // live objects are missed by the marking process. Objects
2804 // allocated after the start of concurrent marking don't need to
2805 // be scanned.
2806 //
2807 // * An object must not be reclaimed if it is on the concurrent
2808 // mark stack. Objects allocated after the start of concurrent
2809 // marking are never pushed on the mark stack.
2810 //
2811 // Nominating only objects allocated after the start of concurrent
2812 // marking is sufficient to meet both constraints. This may miss
2813 // some objects that satisfy the constraints, but the marking data
2814 // structures don't support efficiently performing the needed
2815 // additional tests or scrubbing of the mark stack.
2816 //
2817 // However, we presently only nominate is_typeArray() objects.
2818 // A humongous object containing references induces remembered
2819 // set entries on other regions. In order to reclaim such an
2820 // object, those remembered sets would need to be cleaned up.
2821 //
2822 // We also treat is_typeArray() objects specially, allowing them
2823 // to be reclaimed even if allocated before the start of
2824 // concurrent mark. For this we rely on mark stack insertion to
2825 // exclude is_typeArray() objects, preventing reclaiming an object
2826 // that is in the mark stack. We also rely on the metadata for
2827 // such objects to be built-in and so ensured to be kept live.
2828 // Frequent allocation and drop of large binary blobs is an
2829 // important use case for eager reclaim, and this special handling
2830 // may reduce needed headroom.
2831
2832 return obj->is_typeArray() && is_remset_small(region);
2833 }
2834
2835 public:
2836 RegisterHumongousWithInCSetFastTestClosure()
2837 : _total_humongous(0),
2838 _candidate_humongous(0),
2839 _dcq(&JavaThread::dirty_card_queue_set()) {
2840 }
2841
2842 virtual bool doHeapRegion(HeapRegion* r) {
2843 if (!r->is_starts_humongous()) {
2844 return false;
2845 }
2846 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2847
2848 bool is_candidate = humongous_region_is_candidate(g1h, r);
2849 uint rindex = r->hrm_index();
2850 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2851 if (is_candidate) {
2852 _candidate_humongous++;
2853 g1h->register_humongous_region_with_cset(rindex);
2854 // Is_candidate already filters out humongous object with large remembered sets.
2855 // If we have a humongous object with a few remembered sets, we simply flush these
2856 // remembered set entries into the DCQS. That will result in automatic
2857 // re-evaluation of their remembered set entries during the following evacuation
2858 // phase.
2859 if (!r->rem_set()->is_empty()) {
2860 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2861 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2862 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2863 HeapRegionRemSetIterator hrrs(r->rem_set());
2864 size_t card_index;
2865 while (hrrs.has_next(card_index)) {
2866 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2867 // The remembered set might contain references to already freed
2868 // regions. Filter out such entries to avoid failing card table
2869 // verification.
2870 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2871 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2872 *card_ptr = CardTableModRefBS::dirty_card_val();
2873 _dcq.enqueue(card_ptr);
2874 }
2875 }
2876 }
2877 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2878 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2879 hrrs.n_yielded(), r->rem_set()->occupied());
2880 r->rem_set()->clear_locked();
2881 }
2882 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2883 }
2884 _total_humongous++;
2885
2886 return false;
2887 }
2888
2889 size_t total_humongous() const { return _total_humongous; }
2890 size_t candidate_humongous() const { return _candidate_humongous; }
2891
2892 void flush_rem_set_entries() { _dcq.flush(); }
2893 };
2894
2895 void G1CollectedHeap::register_humongous_regions_with_cset() {
2896 if (!G1EagerReclaimHumongousObjects) {
2897 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2898 return;
2899 }
2900 double time = os::elapsed_counter();
2901
2902 // Collect reclaim candidate information and register candidates with cset.
2903 RegisterHumongousWithInCSetFastTestClosure cl;
2904 heap_region_iterate(&cl);
2905
2906 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2907 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2908 cl.total_humongous(),
2909 cl.candidate_humongous());
2910 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2911
2912 // Finally flush all remembered set entries to re-check into the global DCQS.
2913 cl.flush_rem_set_entries();
2914 }
2915
2916 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2917 public:
2918 bool doHeapRegion(HeapRegion* hr) {
2919 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2920 hr->verify_rem_set();
2921 }
2922 return false;
2923 }
2924 };
2925
2926 uint G1CollectedHeap::num_task_queues() const {
2927 return _task_queues->size();
2928 }
2929
2930 #if TASKQUEUE_STATS
2931 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2932 st->print_raw_cr("GC Task Stats");
2933 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2934 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2935 }
2936
2937 void G1CollectedHeap::print_taskqueue_stats() const {
2938 if (!log_is_enabled(Trace, gc, task, stats)) {
2939 return;
2940 }
2941 Log(gc, task, stats) log;
2942 ResourceMark rm;
2943 outputStream* st = log.trace_stream();
2944
2945 print_taskqueue_stats_hdr(st);
2946
2947 TaskQueueStats totals;
2948 const uint n = num_task_queues();
2949 for (uint i = 0; i < n; ++i) {
2950 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2951 totals += task_queue(i)->stats;
2952 }
2953 st->print_raw("tot "); totals.print(st); st->cr();
2954
2955 DEBUG_ONLY(totals.verify());
2956 }
2957
2958 void G1CollectedHeap::reset_taskqueue_stats() {
2959 const uint n = num_task_queues();
2960 for (uint i = 0; i < n; ++i) {
2961 task_queue(i)->stats.reset();
2962 }
2963 }
2964 #endif // TASKQUEUE_STATS
2965
2966 void G1CollectedHeap::wait_for_root_region_scanning() {
2967 double scan_wait_start = os::elapsedTime();
2968 // We have to wait until the CM threads finish scanning the
2969 // root regions as it's the only way to ensure that all the
2970 // objects on them have been correctly scanned before we start
2971 // moving them during the GC.
2972 bool waited = _cm->root_regions()->wait_until_scan_finished();
2973 double wait_time_ms = 0.0;
2974 if (waited) {
2975 double scan_wait_end = os::elapsedTime();
2976 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2977 }
2978 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2979 }
2980
2981 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2982 private:
2983 G1HRPrinter* _hr_printer;
2984 public:
2985 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2986
2987 virtual bool doHeapRegion(HeapRegion* r) {
2988 _hr_printer->cset(r);
2989 return false;
2990 }
2991 };
2992
2993 void G1CollectedHeap::start_new_collection_set() {
2994 collection_set()->start_incremental_building();
2995
2996 clear_cset_fast_test();
2997
2998 guarantee(_eden.length() == 0, "eden should have been cleared");
2999 g1_policy()->transfer_survivors_to_cset(survivor());
3000 }
3001
3002 bool
3003 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3004 assert_at_safepoint(true /* should_be_vm_thread */);
3005 guarantee(!is_gc_active(), "collection is not reentrant");
3006
3007 if (GCLocker::check_active_before_gc()) {
3008 return false;
3009 }
3010
3011 _gc_timer_stw->register_gc_start();
3012
3013 GCIdMark gc_id_mark;
3014 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3015
3016 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3017 ResourceMark rm;
3018
3019 g1_policy()->note_gc_start();
3020
3021 wait_for_root_region_scanning();
3022
3023 print_heap_before_gc();
3024 print_heap_regions();
3025 trace_heap_before_gc(_gc_tracer_stw);
3026
3027 _verifier->verify_region_sets_optional();
3028 _verifier->verify_dirty_young_regions();
3029
3030 // We should not be doing initial mark unless the conc mark thread is running
3031 if (!_cmThread->should_terminate()) {
3032 // This call will decide whether this pause is an initial-mark
3033 // pause. If it is, during_initial_mark_pause() will return true
3034 // for the duration of this pause.
3035 g1_policy()->decide_on_conc_mark_initiation();
3036 }
3037
3038 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3039 assert(!collector_state()->during_initial_mark_pause() ||
3040 collector_state()->gcs_are_young(), "sanity");
3041
3042 // We also do not allow mixed GCs during marking.
3043 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3044
3045 // Record whether this pause is an initial mark. When the current
3046 // thread has completed its logging output and it's safe to signal
3047 // the CM thread, the flag's value in the policy has been reset.
3048 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3049
3050 // Inner scope for scope based logging, timers, and stats collection
3051 {
3052 EvacuationInfo evacuation_info;
3053
3054 if (collector_state()->during_initial_mark_pause()) {
3055 // We are about to start a marking cycle, so we increment the
3056 // full collection counter.
3057 increment_old_marking_cycles_started();
3058 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3059 }
3060
3061 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3062
3063 GCTraceCPUTime tcpu;
3064
3065 FormatBuffer<> gc_string("Pause ");
3066 if (collector_state()->during_initial_mark_pause()) {
3067 gc_string.append("Initial Mark");
3068 } else if (collector_state()->gcs_are_young()) {
3069 gc_string.append("Young");
3070 } else {
3071 gc_string.append("Mixed");
3072 }
3073 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3074
3075 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3076 workers()->active_workers(),
3077 Threads::number_of_non_daemon_threads());
3078 workers()->update_active_workers(active_workers);
3079 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3080
3081 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3082 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3083
3084 // If the secondary_free_list is not empty, append it to the
3085 // free_list. No need to wait for the cleanup operation to finish;
3086 // the region allocation code will check the secondary_free_list
3087 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3088 // set, skip this step so that the region allocation code has to
3089 // get entries from the secondary_free_list.
3090 if (!G1StressConcRegionFreeing) {
3091 append_secondary_free_list_if_not_empty_with_lock();
3092 }
3093
3094 G1HeapTransition heap_transition(this);
3095 size_t heap_used_bytes_before_gc = used();
3096
3097 // Don't dynamically change the number of GC threads this early. A value of
3098 // 0 is used to indicate serial work. When parallel work is done,
3099 // it will be set.
3100
3101 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3102 IsGCActiveMark x;
3103
3104 gc_prologue(false);
3105 increment_total_collections(false /* full gc */);
3106 increment_gc_time_stamp();
3107
3108 if (VerifyRememberedSets) {
3109 log_info(gc, verify)("[Verifying RemSets before GC]");
3110 VerifyRegionRemSetClosure v_cl;
3111 heap_region_iterate(&v_cl);
3112 }
3113
3114 _verifier->verify_before_gc();
3115
3116 _verifier->check_bitmaps("GC Start");
3117
3118 #if defined(COMPILER2) || INCLUDE_JVMCI
3119 DerivedPointerTable::clear();
3120 #endif
3121
3122 // Please see comment in g1CollectedHeap.hpp and
3123 // G1CollectedHeap::ref_processing_init() to see how
3124 // reference processing currently works in G1.
3125
3126 // Enable discovery in the STW reference processor
3127 if (g1_policy()->should_process_references()) {
3128 ref_processor_stw()->enable_discovery();
3129 } else {
3130 ref_processor_stw()->disable_discovery();
3131 }
3132
3133 {
3134 // We want to temporarily turn off discovery by the
3135 // CM ref processor, if necessary, and turn it back on
3136 // on again later if we do. Using a scoped
3137 // NoRefDiscovery object will do this.
3138 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3139
3140 // Forget the current alloc region (we might even choose it to be part
3141 // of the collection set!).
3142 _allocator->release_mutator_alloc_region();
3143
3144 // This timing is only used by the ergonomics to handle our pause target.
3145 // It is unclear why this should not include the full pause. We will
3146 // investigate this in CR 7178365.
3147 //
3148 // Preserving the old comment here if that helps the investigation:
3149 //
3150 // The elapsed time induced by the start time below deliberately elides
3151 // the possible verification above.
3152 double sample_start_time_sec = os::elapsedTime();
3153
3154 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3155
3156 if (collector_state()->during_initial_mark_pause()) {
3157 concurrent_mark()->checkpointRootsInitialPre();
3158 }
3159
3160 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3161
3162 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3163
3164 // Make sure the remembered sets are up to date. This needs to be
3165 // done before register_humongous_regions_with_cset(), because the
3166 // remembered sets are used there to choose eager reclaim candidates.
3167 // If the remembered sets are not up to date we might miss some
3168 // entries that need to be handled.
3169 g1_rem_set()->cleanupHRRS();
3170
3171 register_humongous_regions_with_cset();
3172
3173 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3174
3175 // We call this after finalize_cset() to
3176 // ensure that the CSet has been finalized.
3177 _cm->verify_no_cset_oops();
3178
3179 if (_hr_printer.is_active()) {
3180 G1PrintCollectionSetClosure cl(&_hr_printer);
3181 _collection_set.iterate(&cl);
3182 }
3183
3184 // Initialize the GC alloc regions.
3185 _allocator->init_gc_alloc_regions(evacuation_info);
3186
3187 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3188 pre_evacuate_collection_set();
3189
3190 // Actually do the work...
3191 evacuate_collection_set(evacuation_info, &per_thread_states);
3192
3193 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3194
3195 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3196 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3197
3198 eagerly_reclaim_humongous_regions();
3199
3200 record_obj_copy_mem_stats();
3201 _survivor_evac_stats.adjust_desired_plab_sz();
3202 _old_evac_stats.adjust_desired_plab_sz();
3203
3204 double start = os::elapsedTime();
3205 start_new_collection_set();
3206 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3207
3208 if (evacuation_failed()) {
3209 set_used(recalculate_used());
3210 if (_archive_allocator != NULL) {
3211 _archive_allocator->clear_used();
3212 }
3213 for (uint i = 0; i < ParallelGCThreads; i++) {
3214 if (_evacuation_failed_info_array[i].has_failed()) {
3215 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3216 }
3217 }
3218 } else {
3219 // The "used" of the the collection set have already been subtracted
3220 // when they were freed. Add in the bytes evacuated.
3221 increase_used(g1_policy()->bytes_copied_during_gc());
3222 }
3223
3224 if (collector_state()->during_initial_mark_pause()) {
3225 // We have to do this before we notify the CM threads that
3226 // they can start working to make sure that all the
3227 // appropriate initialization is done on the CM object.
3228 concurrent_mark()->checkpointRootsInitialPost();
3229 collector_state()->set_mark_in_progress(true);
3230 // Note that we don't actually trigger the CM thread at
3231 // this point. We do that later when we're sure that
3232 // the current thread has completed its logging output.
3233 }
3234
3235 allocate_dummy_regions();
3236
3237 _allocator->init_mutator_alloc_region();
3238
3239 {
3240 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3241 if (expand_bytes > 0) {
3242 size_t bytes_before = capacity();
3243 // No need for an ergo logging here,
3244 // expansion_amount() does this when it returns a value > 0.
3245 double expand_ms;
3246 if (!expand(expand_bytes, _workers, &expand_ms)) {
3247 // We failed to expand the heap. Cannot do anything about it.
3248 }
3249 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3250 }
3251 }
3252
3253 // We redo the verification but now wrt to the new CSet which
3254 // has just got initialized after the previous CSet was freed.
3255 _cm->verify_no_cset_oops();
3256
3257 // This timing is only used by the ergonomics to handle our pause target.
3258 // It is unclear why this should not include the full pause. We will
3259 // investigate this in CR 7178365.
3260 double sample_end_time_sec = os::elapsedTime();
3261 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3262 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3263 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3264
3265 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3266 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3267
3268 MemoryService::track_memory_usage();
3269
3270 if (VerifyRememberedSets) {
3271 log_info(gc, verify)("[Verifying RemSets after GC]");
3272 VerifyRegionRemSetClosure v_cl;
3273 heap_region_iterate(&v_cl);
3274 }
3275
3276 _verifier->verify_after_gc();
3277 _verifier->check_bitmaps("GC End");
3278
3279 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3280 ref_processor_stw()->verify_no_references_recorded();
3281
3282 // CM reference discovery will be re-enabled if necessary.
3283 }
3284
3285 #ifdef TRACESPINNING
3286 ParallelTaskTerminator::print_termination_counts();
3287 #endif
3288
3289 gc_epilogue(false);
3290 }
3291
3292 // Print the remainder of the GC log output.
3293 if (evacuation_failed()) {
3294 log_info(gc)("To-space exhausted");
3295 }
3296
3297 g1_policy()->print_phases();
3298 heap_transition.print();
3299
3300 // It is not yet to safe to tell the concurrent mark to
3301 // start as we have some optional output below. We don't want the
3302 // output from the concurrent mark thread interfering with this
3303 // logging output either.
3304
3305 _hrm.verify_optional();
3306 _verifier->verify_region_sets_optional();
3307
3308 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3309 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3310
3311 print_heap_after_gc();
3312 print_heap_regions();
3313 trace_heap_after_gc(_gc_tracer_stw);
3314
3315 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3316 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3317 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3318 // before any GC notifications are raised.
3319 g1mm()->update_sizes();
3320
3321 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3322 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3323 _gc_timer_stw->register_gc_end();
3324 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3325 }
3326 // It should now be safe to tell the concurrent mark thread to start
3327 // without its logging output interfering with the logging output
3328 // that came from the pause.
3329
3330 if (should_start_conc_mark) {
3331 // CAUTION: after the doConcurrentMark() call below,
3332 // the concurrent marking thread(s) could be running
3333 // concurrently with us. Make sure that anything after
3334 // this point does not assume that we are the only GC thread
3335 // running. Note: of course, the actual marking work will
3336 // not start until the safepoint itself is released in
3337 // SuspendibleThreadSet::desynchronize().
3338 doConcurrentMark();
3339 }
3340
3341 return true;
3342 }
3343
3344 void G1CollectedHeap::remove_self_forwarding_pointers() {
3345 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3346 workers()->run_task(&rsfp_task);
3347 }
3348
3349 void G1CollectedHeap::restore_after_evac_failure() {
3350 double remove_self_forwards_start = os::elapsedTime();
3351
3352 remove_self_forwarding_pointers();
3353 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3354 _preserved_marks_set.restore(&task_executor);
3355
3356 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3357 }
3358
3359 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3360 if (!_evacuation_failed) {
3361 _evacuation_failed = true;
3362 }
3363
3364 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3365 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3366 }
3367
3368 bool G1ParEvacuateFollowersClosure::offer_termination() {
3369 G1ParScanThreadState* const pss = par_scan_state();
3370 start_term_time();
3371 const bool res = terminator()->offer_termination();
3372 end_term_time();
3373 return res;
3374 }
3375
3376 void G1ParEvacuateFollowersClosure::do_void() {
3377 G1ParScanThreadState* const pss = par_scan_state();
3378 pss->trim_queue();
3379 do {
3380 pss->steal_and_trim_queue(queues());
3381 } while (!offer_termination());
3382 }
3383
3384 class G1ParTask : public AbstractGangTask {
3385 protected:
3386 G1CollectedHeap* _g1h;
3387 G1ParScanThreadStateSet* _pss;
3388 RefToScanQueueSet* _queues;
3389 G1RootProcessor* _root_processor;
3390 ParallelTaskTerminator _terminator;
3391 uint _n_workers;
3392
3393 public:
3394 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3395 : AbstractGangTask("G1 collection"),
3396 _g1h(g1h),
3397 _pss(per_thread_states),
3398 _queues(task_queues),
3399 _root_processor(root_processor),
3400 _terminator(n_workers, _queues),
3401 _n_workers(n_workers)
3402 {}
3403
3404 void work(uint worker_id) {
3405 if (worker_id >= _n_workers) return; // no work needed this round
3406
3407 double start_sec = os::elapsedTime();
3408 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3409
3410 {
3411 ResourceMark rm;
3412 HandleMark hm;
3413
3414 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3415
3416 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3417 pss->set_ref_processor(rp);
3418
3419 double start_strong_roots_sec = os::elapsedTime();
3420
3421 _root_processor->evacuate_roots(pss->closures(), worker_id);
3422
3423 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3424 // treating the nmethods visited to act as roots for concurrent marking.
3425 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3426 // objects copied by the current evacuation.
3427 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3428 pss->closures()->weak_codeblobs(),
3429 worker_id);
3430
3431 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3432
3433 double term_sec = 0.0;
3434 size_t evac_term_attempts = 0;
3435 {
3436 double start = os::elapsedTime();
3437 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3438 evac.do_void();
3439
3440 evac_term_attempts = evac.term_attempts();
3441 term_sec = evac.term_time();
3442 double elapsed_sec = os::elapsedTime() - start;
3443 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3444 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3445 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3446 }
3447
3448 assert(pss->queue_is_empty(), "should be empty");
3449
3450 if (log_is_enabled(Debug, gc, task, stats)) {
3451 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3452 size_t lab_waste;
3453 size_t lab_undo_waste;
3454 pss->waste(lab_waste, lab_undo_waste);
3455 _g1h->print_termination_stats(worker_id,
3456 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3457 strong_roots_sec * 1000.0, /* strong roots time */
3458 term_sec * 1000.0, /* evac term time */
3459 evac_term_attempts, /* evac term attempts */
3460 lab_waste, /* alloc buffer waste */
3461 lab_undo_waste /* undo waste */
3462 );
3463 }
3464
3465 // Close the inner scope so that the ResourceMark and HandleMark
3466 // destructors are executed here and are included as part of the
3467 // "GC Worker Time".
3468 }
3469 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3470 }
3471 };
3472
3473 void G1CollectedHeap::print_termination_stats_hdr() {
3474 log_debug(gc, task, stats)("GC Termination Stats");
3475 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3476 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3477 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3478 }
3479
3480 void G1CollectedHeap::print_termination_stats(uint worker_id,
3481 double elapsed_ms,
3482 double strong_roots_ms,
3483 double term_ms,
3484 size_t term_attempts,
3485 size_t alloc_buffer_waste,
3486 size_t undo_waste) const {
3487 log_debug(gc, task, stats)
3488 ("%3d %9.2f %9.2f %6.2f "
3489 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3490 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3491 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3492 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3493 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3494 alloc_buffer_waste * HeapWordSize / K,
3495 undo_waste * HeapWordSize / K);
3496 }
3497
3498 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3499 private:
3500 BoolObjectClosure* _is_alive;
3501 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3502
3503 int _initial_string_table_size;
3504 int _initial_symbol_table_size;
3505
3506 bool _process_strings;
3507 int _strings_processed;
3508 int _strings_removed;
3509
3510 bool _process_symbols;
3511 int _symbols_processed;
3512 int _symbols_removed;
3513
3514 bool _process_string_dedup;
3515
3516 public:
3517 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3518 AbstractGangTask("String/Symbol Unlinking"),
3519 _is_alive(is_alive),
3520 _dedup_closure(is_alive, NULL, false),
3521 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3522 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3523 _process_string_dedup(process_string_dedup) {
3524
3525 _initial_string_table_size = StringTable::the_table()->table_size();
3526 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3527 if (process_strings) {
3528 StringTable::clear_parallel_claimed_index();
3529 }
3530 if (process_symbols) {
3531 SymbolTable::clear_parallel_claimed_index();
3532 }
3533 }
3534
3535 ~G1StringAndSymbolCleaningTask() {
3536 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3537 "claim value %d after unlink less than initial string table size %d",
3538 StringTable::parallel_claimed_index(), _initial_string_table_size);
3539 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3540 "claim value %d after unlink less than initial symbol table size %d",
3541 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3542
3543 log_info(gc, stringtable)(
3544 "Cleaned string and symbol table, "
3545 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3546 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3547 strings_processed(), strings_removed(),
3548 symbols_processed(), symbols_removed());
3549 }
3550
3551 void work(uint worker_id) {
3552 int strings_processed = 0;
3553 int strings_removed = 0;
3554 int symbols_processed = 0;
3555 int symbols_removed = 0;
3556 if (_process_strings) {
3557 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3558 Atomic::add(strings_processed, &_strings_processed);
3559 Atomic::add(strings_removed, &_strings_removed);
3560 }
3561 if (_process_symbols) {
3562 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3563 Atomic::add(symbols_processed, &_symbols_processed);
3564 Atomic::add(symbols_removed, &_symbols_removed);
3565 }
3566 if (_process_string_dedup) {
3567 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3568 }
3569 }
3570
3571 size_t strings_processed() const { return (size_t)_strings_processed; }
3572 size_t strings_removed() const { return (size_t)_strings_removed; }
3573
3574 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3575 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3576 };
3577
3578 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3579 private:
3580 static Monitor* _lock;
3581
3582 BoolObjectClosure* const _is_alive;
3583 const bool _unloading_occurred;
3584 const uint _num_workers;
3585
3586 // Variables used to claim nmethods.
3587 CompiledMethod* _first_nmethod;
3588 volatile CompiledMethod* _claimed_nmethod;
3589
3590 // The list of nmethods that need to be processed by the second pass.
3591 volatile CompiledMethod* _postponed_list;
3592 volatile uint _num_entered_barrier;
3593
3594 public:
3595 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3596 _is_alive(is_alive),
3597 _unloading_occurred(unloading_occurred),
3598 _num_workers(num_workers),
3599 _first_nmethod(NULL),
3600 _claimed_nmethod(NULL),
3601 _postponed_list(NULL),
3602 _num_entered_barrier(0)
3603 {
3604 CompiledMethod::increase_unloading_clock();
3605 // Get first alive nmethod
3606 CompiledMethodIterator iter = CompiledMethodIterator();
3607 if(iter.next_alive()) {
3608 _first_nmethod = iter.method();
3609 }
3610 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3611 }
3612
3613 ~G1CodeCacheUnloadingTask() {
3614 CodeCache::verify_clean_inline_caches();
3615
3616 CodeCache::set_needs_cache_clean(false);
3617 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3618
3619 CodeCache::verify_icholder_relocations();
3620 }
3621
3622 private:
3623 void add_to_postponed_list(CompiledMethod* nm) {
3624 CompiledMethod* old;
3625 do {
3626 old = (CompiledMethod*)_postponed_list;
3627 nm->set_unloading_next(old);
3628 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3629 }
3630
3631 void clean_nmethod(CompiledMethod* nm) {
3632 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3633
3634 if (postponed) {
3635 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3636 add_to_postponed_list(nm);
3637 }
3638
3639 // Mark that this thread has been cleaned/unloaded.
3640 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3641 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3642 }
3643
3644 void clean_nmethod_postponed(CompiledMethod* nm) {
3645 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3646 }
3647
3648 static const int MaxClaimNmethods = 16;
3649
3650 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3651 CompiledMethod* first;
3652 CompiledMethodIterator last;
3653
3654 do {
3655 *num_claimed_nmethods = 0;
3656
3657 first = (CompiledMethod*)_claimed_nmethod;
3658 last = CompiledMethodIterator(first);
3659
3660 if (first != NULL) {
3661
3662 for (int i = 0; i < MaxClaimNmethods; i++) {
3663 if (!last.next_alive()) {
3664 break;
3665 }
3666 claimed_nmethods[i] = last.method();
3667 (*num_claimed_nmethods)++;
3668 }
3669 }
3670
3671 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3672 }
3673
3674 CompiledMethod* claim_postponed_nmethod() {
3675 CompiledMethod* claim;
3676 CompiledMethod* next;
3677
3678 do {
3679 claim = (CompiledMethod*)_postponed_list;
3680 if (claim == NULL) {
3681 return NULL;
3682 }
3683
3684 next = claim->unloading_next();
3685
3686 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3687
3688 return claim;
3689 }
3690
3691 public:
3692 // Mark that we're done with the first pass of nmethod cleaning.
3693 void barrier_mark(uint worker_id) {
3694 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3695 _num_entered_barrier++;
3696 if (_num_entered_barrier == _num_workers) {
3697 ml.notify_all();
3698 }
3699 }
3700
3701 // See if we have to wait for the other workers to
3702 // finish their first-pass nmethod cleaning work.
3703 void barrier_wait(uint worker_id) {
3704 if (_num_entered_barrier < _num_workers) {
3705 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3706 while (_num_entered_barrier < _num_workers) {
3707 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3708 }
3709 }
3710 }
3711
3712 // Cleaning and unloading of nmethods. Some work has to be postponed
3713 // to the second pass, when we know which nmethods survive.
3714 void work_first_pass(uint worker_id) {
3715 // The first nmethods is claimed by the first worker.
3716 if (worker_id == 0 && _first_nmethod != NULL) {
3717 clean_nmethod(_first_nmethod);
3718 _first_nmethod = NULL;
3719 }
3720
3721 int num_claimed_nmethods;
3722 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3723
3724 while (true) {
3725 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3726
3727 if (num_claimed_nmethods == 0) {
3728 break;
3729 }
3730
3731 for (int i = 0; i < num_claimed_nmethods; i++) {
3732 clean_nmethod(claimed_nmethods[i]);
3733 }
3734 }
3735 }
3736
3737 void work_second_pass(uint worker_id) {
3738 CompiledMethod* nm;
3739 // Take care of postponed nmethods.
3740 while ((nm = claim_postponed_nmethod()) != NULL) {
3741 clean_nmethod_postponed(nm);
3742 }
3743 }
3744 };
3745
3746 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3747
3748 class G1KlassCleaningTask : public StackObj {
3749 BoolObjectClosure* _is_alive;
3750 volatile jint _clean_klass_tree_claimed;
3751 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3752
3753 public:
3754 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3755 _is_alive(is_alive),
3756 _clean_klass_tree_claimed(0),
3757 _klass_iterator() {
3758 }
3759
3760 private:
3761 bool claim_clean_klass_tree_task() {
3762 if (_clean_klass_tree_claimed) {
3763 return false;
3764 }
3765
3766 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3767 }
3768
3769 InstanceKlass* claim_next_klass() {
3770 Klass* klass;
3771 do {
3772 klass =_klass_iterator.next_klass();
3773 } while (klass != NULL && !klass->is_instance_klass());
3774
3775 // this can be null so don't call InstanceKlass::cast
3776 return static_cast<InstanceKlass*>(klass);
3777 }
3778
3779 public:
3780
3781 void clean_klass(InstanceKlass* ik) {
3782 ik->clean_weak_instanceklass_links(_is_alive);
3783 }
3784
3785 void work() {
3786 ResourceMark rm;
3787
3788 // One worker will clean the subklass/sibling klass tree.
3789 if (claim_clean_klass_tree_task()) {
3790 Klass::clean_subklass_tree(_is_alive);
3791 }
3792
3793 // All workers will help cleaning the classes,
3794 InstanceKlass* klass;
3795 while ((klass = claim_next_klass()) != NULL) {
3796 clean_klass(klass);
3797 }
3798 }
3799 };
3800
3801 class G1ResolvedMethodCleaningTask : public StackObj {
3802 BoolObjectClosure* _is_alive;
3803 volatile jint _resolved_method_task_claimed;
3804 public:
3805 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3806 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3807
3808 bool claim_resolved_method_task() {
3809 if (_resolved_method_task_claimed) {
3810 return false;
3811 }
3812 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3813 }
3814
3815 // These aren't big, one thread can do it all.
3816 void work() {
3817 if (claim_resolved_method_task()) {
3818 ResolvedMethodTable::unlink(_is_alive);
3819 }
3820 }
3821 };
3822
3823
3824 // To minimize the remark pause times, the tasks below are done in parallel.
3825 class G1ParallelCleaningTask : public AbstractGangTask {
3826 private:
3827 G1StringAndSymbolCleaningTask _string_symbol_task;
3828 G1CodeCacheUnloadingTask _code_cache_task;
3829 G1KlassCleaningTask _klass_cleaning_task;
3830 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3831
3832 public:
3833 // The constructor is run in the VMThread.
3834 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3835 AbstractGangTask("Parallel Cleaning"),
3836 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3837 _code_cache_task(num_workers, is_alive, unloading_occurred),
3838 _klass_cleaning_task(is_alive),
3839 _resolved_method_cleaning_task(is_alive) {
3840 }
3841
3842 // The parallel work done by all worker threads.
3843 void work(uint worker_id) {
3844 // Do first pass of code cache cleaning.
3845 _code_cache_task.work_first_pass(worker_id);
3846
3847 // Let the threads mark that the first pass is done.
3848 _code_cache_task.barrier_mark(worker_id);
3849
3850 // Clean the Strings and Symbols.
3851 _string_symbol_task.work(worker_id);
3852
3853 // Clean unreferenced things in the ResolvedMethodTable
3854 _resolved_method_cleaning_task.work();
3855
3856 // Wait for all workers to finish the first code cache cleaning pass.
3857 _code_cache_task.barrier_wait(worker_id);
3858
3859 // Do the second code cache cleaning work, which realize on
3860 // the liveness information gathered during the first pass.
3861 _code_cache_task.work_second_pass(worker_id);
3862
3863 // Clean all klasses that were not unloaded.
3864 _klass_cleaning_task.work();
3865 }
3866 };
3867
3868
3869 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3870 bool class_unloading_occurred) {
3871 uint n_workers = workers()->active_workers();
3872
3873 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3874 workers()->run_task(&g1_unlink_task);
3875 }
3876
3877 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3878 bool process_strings,
3879 bool process_symbols,
3880 bool process_string_dedup) {
3881 if (!process_strings && !process_symbols && !process_string_dedup) {
3882 // Nothing to clean.
3883 return;
3884 }
3885
3886 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3887 workers()->run_task(&g1_unlink_task);
3888
3889 }
3890
3891 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3892 private:
3893 DirtyCardQueueSet* _queue;
3894 G1CollectedHeap* _g1h;
3895 public:
3896 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3897 _queue(queue), _g1h(g1h) { }
3898
3899 virtual void work(uint worker_id) {
3900 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3901 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3902
3903 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3904 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3905
3906 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3907 }
3908 };
3909
3910 void G1CollectedHeap::redirty_logged_cards() {
3911 double redirty_logged_cards_start = os::elapsedTime();
3912
3913 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3914 dirty_card_queue_set().reset_for_par_iteration();
3915 workers()->run_task(&redirty_task);
3916
3917 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3918 dcq.merge_bufferlists(&dirty_card_queue_set());
3919 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3920
3921 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3922 }
3923
3924 // Weak Reference Processing support
3925
3926 // An always "is_alive" closure that is used to preserve referents.
3927 // If the object is non-null then it's alive. Used in the preservation
3928 // of referent objects that are pointed to by reference objects
3929 // discovered by the CM ref processor.
3930 class G1AlwaysAliveClosure: public BoolObjectClosure {
3931 G1CollectedHeap* _g1;
3932 public:
3933 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3934 bool do_object_b(oop p) {
3935 if (p != NULL) {
3936 return true;
3937 }
3938 return false;
3939 }
3940 };
3941
3942 bool G1STWIsAliveClosure::do_object_b(oop p) {
3943 // An object is reachable if it is outside the collection set,
3944 // or is inside and copied.
3945 return !_g1->is_in_cset(p) || p->is_forwarded();
3946 }
3947
3948 // Non Copying Keep Alive closure
3949 class G1KeepAliveClosure: public OopClosure {
3950 G1CollectedHeap* _g1;
3951 public:
3952 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3953 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3954 void do_oop(oop* p) {
3955 oop obj = *p;
3956 assert(obj != NULL, "the caller should have filtered out NULL values");
3957
3958 const InCSetState cset_state = _g1->in_cset_state(obj);
3959 if (!cset_state.is_in_cset_or_humongous()) {
3960 return;
3961 }
3962 if (cset_state.is_in_cset()) {
3963 assert( obj->is_forwarded(), "invariant" );
3964 *p = obj->forwardee();
3965 } else {
3966 assert(!obj->is_forwarded(), "invariant" );
3967 assert(cset_state.is_humongous(),
3968 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3969 _g1->set_humongous_is_live(obj);
3970 }
3971 }
3972 };
3973
3974 // Copying Keep Alive closure - can be called from both
3975 // serial and parallel code as long as different worker
3976 // threads utilize different G1ParScanThreadState instances
3977 // and different queues.
3978
3979 class G1CopyingKeepAliveClosure: public OopClosure {
3980 G1CollectedHeap* _g1h;
3981 OopClosure* _copy_non_heap_obj_cl;
3982 G1ParScanThreadState* _par_scan_state;
3983
3984 public:
3985 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3986 OopClosure* non_heap_obj_cl,
3987 G1ParScanThreadState* pss):
3988 _g1h(g1h),
3989 _copy_non_heap_obj_cl(non_heap_obj_cl),
3990 _par_scan_state(pss)
3991 {}
3992
3993 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3994 virtual void do_oop( oop* p) { do_oop_work(p); }
3995
3996 template <class T> void do_oop_work(T* p) {
3997 oop obj = oopDesc::load_decode_heap_oop(p);
3998
3999 if (_g1h->is_in_cset_or_humongous(obj)) {
4000 // If the referent object has been forwarded (either copied
4001 // to a new location or to itself in the event of an
4002 // evacuation failure) then we need to update the reference
4003 // field and, if both reference and referent are in the G1
4004 // heap, update the RSet for the referent.
4005 //
4006 // If the referent has not been forwarded then we have to keep
4007 // it alive by policy. Therefore we have copy the referent.
4008 //
4009 // If the reference field is in the G1 heap then we can push
4010 // on the PSS queue. When the queue is drained (after each
4011 // phase of reference processing) the object and it's followers
4012 // will be copied, the reference field set to point to the
4013 // new location, and the RSet updated. Otherwise we need to
4014 // use the the non-heap or metadata closures directly to copy
4015 // the referent object and update the pointer, while avoiding
4016 // updating the RSet.
4017
4018 if (_g1h->is_in_g1_reserved(p)) {
4019 _par_scan_state->push_on_queue(p);
4020 } else {
4021 assert(!Metaspace::contains((const void*)p),
4022 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4023 _copy_non_heap_obj_cl->do_oop(p);
4024 }
4025 }
4026 }
4027 };
4028
4029 // Serial drain queue closure. Called as the 'complete_gc'
4030 // closure for each discovered list in some of the
4031 // reference processing phases.
4032
4033 class G1STWDrainQueueClosure: public VoidClosure {
4034 protected:
4035 G1CollectedHeap* _g1h;
4036 G1ParScanThreadState* _par_scan_state;
4037
4038 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4039
4040 public:
4041 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4042 _g1h(g1h),
4043 _par_scan_state(pss)
4044 { }
4045
4046 void do_void() {
4047 G1ParScanThreadState* const pss = par_scan_state();
4048 pss->trim_queue();
4049 }
4050 };
4051
4052 // Parallel Reference Processing closures
4053
4054 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4055 // processing during G1 evacuation pauses.
4056
4057 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4058 private:
4059 G1CollectedHeap* _g1h;
4060 G1ParScanThreadStateSet* _pss;
4061 RefToScanQueueSet* _queues;
4062 WorkGang* _workers;
4063 uint _active_workers;
4064
4065 public:
4066 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4067 G1ParScanThreadStateSet* per_thread_states,
4068 WorkGang* workers,
4069 RefToScanQueueSet *task_queues,
4070 uint n_workers) :
4071 _g1h(g1h),
4072 _pss(per_thread_states),
4073 _queues(task_queues),
4074 _workers(workers),
4075 _active_workers(n_workers)
4076 {
4077 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4078 }
4079
4080 // Executes the given task using concurrent marking worker threads.
4081 virtual void execute(ProcessTask& task);
4082 virtual void execute(EnqueueTask& task);
4083 };
4084
4085 // Gang task for possibly parallel reference processing
4086
4087 class G1STWRefProcTaskProxy: public AbstractGangTask {
4088 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4089 ProcessTask& _proc_task;
4090 G1CollectedHeap* _g1h;
4091 G1ParScanThreadStateSet* _pss;
4092 RefToScanQueueSet* _task_queues;
4093 ParallelTaskTerminator* _terminator;
4094
4095 public:
4096 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4097 G1CollectedHeap* g1h,
4098 G1ParScanThreadStateSet* per_thread_states,
4099 RefToScanQueueSet *task_queues,
4100 ParallelTaskTerminator* terminator) :
4101 AbstractGangTask("Process reference objects in parallel"),
4102 _proc_task(proc_task),
4103 _g1h(g1h),
4104 _pss(per_thread_states),
4105 _task_queues(task_queues),
4106 _terminator(terminator)
4107 {}
4108
4109 virtual void work(uint worker_id) {
4110 // The reference processing task executed by a single worker.
4111 ResourceMark rm;
4112 HandleMark hm;
4113
4114 G1STWIsAliveClosure is_alive(_g1h);
4115
4116 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4117 pss->set_ref_processor(NULL);
4118
4119 // Keep alive closure.
4120 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4121
4122 // Complete GC closure
4123 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4124
4125 // Call the reference processing task's work routine.
4126 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4127
4128 // Note we cannot assert that the refs array is empty here as not all
4129 // of the processing tasks (specifically phase2 - pp2_work) execute
4130 // the complete_gc closure (which ordinarily would drain the queue) so
4131 // the queue may not be empty.
4132 }
4133 };
4134
4135 // Driver routine for parallel reference processing.
4136 // Creates an instance of the ref processing gang
4137 // task and has the worker threads execute it.
4138 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4139 assert(_workers != NULL, "Need parallel worker threads.");
4140
4141 ParallelTaskTerminator terminator(_active_workers, _queues);
4142 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4143
4144 _workers->run_task(&proc_task_proxy);
4145 }
4146
4147 // Gang task for parallel reference enqueueing.
4148
4149 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4150 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4151 EnqueueTask& _enq_task;
4152
4153 public:
4154 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4155 AbstractGangTask("Enqueue reference objects in parallel"),
4156 _enq_task(enq_task)
4157 { }
4158
4159 virtual void work(uint worker_id) {
4160 _enq_task.work(worker_id);
4161 }
4162 };
4163
4164 // Driver routine for parallel reference enqueueing.
4165 // Creates an instance of the ref enqueueing gang
4166 // task and has the worker threads execute it.
4167
4168 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4169 assert(_workers != NULL, "Need parallel worker threads.");
4170
4171 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4172
4173 _workers->run_task(&enq_task_proxy);
4174 }
4175
4176 // End of weak reference support closures
4177
4178 // Abstract task used to preserve (i.e. copy) any referent objects
4179 // that are in the collection set and are pointed to by reference
4180 // objects discovered by the CM ref processor.
4181
4182 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4183 protected:
4184 G1CollectedHeap* _g1h;
4185 G1ParScanThreadStateSet* _pss;
4186 RefToScanQueueSet* _queues;
4187 ParallelTaskTerminator _terminator;
4188 uint _n_workers;
4189
4190 public:
4191 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4192 AbstractGangTask("ParPreserveCMReferents"),
4193 _g1h(g1h),
4194 _pss(per_thread_states),
4195 _queues(task_queues),
4196 _terminator(workers, _queues),
4197 _n_workers(workers)
4198 {
4199 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4200 }
4201
4202 void work(uint worker_id) {
4203 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4204
4205 ResourceMark rm;
4206 HandleMark hm;
4207
4208 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4209 pss->set_ref_processor(NULL);
4210 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4211
4212 // Is alive closure
4213 G1AlwaysAliveClosure always_alive(_g1h);
4214
4215 // Copying keep alive closure. Applied to referent objects that need
4216 // to be copied.
4217 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4218
4219 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4220
4221 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4222 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4223
4224 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4225 // So this must be true - but assert just in case someone decides to
4226 // change the worker ids.
4227 assert(worker_id < limit, "sanity");
4228 assert(!rp->discovery_is_atomic(), "check this code");
4229
4230 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4231 for (uint idx = worker_id; idx < limit; idx += stride) {
4232 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4233
4234 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4235 while (iter.has_next()) {
4236 // Since discovery is not atomic for the CM ref processor, we
4237 // can see some null referent objects.
4238 iter.load_ptrs(DEBUG_ONLY(true));
4239 oop ref = iter.obj();
4240
4241 // This will filter nulls.
4242 if (iter.is_referent_alive()) {
4243 iter.make_referent_alive();
4244 }
4245 iter.move_to_next();
4246 }
4247 }
4248
4249 // Drain the queue - which may cause stealing
4250 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4251 drain_queue.do_void();
4252 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4253 assert(pss->queue_is_empty(), "should be");
4254 }
4255 };
4256
4257 void G1CollectedHeap::process_weak_jni_handles() {
4258 double ref_proc_start = os::elapsedTime();
4259
4260 G1STWIsAliveClosure is_alive(this);
4261 G1KeepAliveClosure keep_alive(this);
4262 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4263
4264 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4265 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4266 }
4267
4268 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4269 // Any reference objects, in the collection set, that were 'discovered'
4270 // by the CM ref processor should have already been copied (either by
4271 // applying the external root copy closure to the discovered lists, or
4272 // by following an RSet entry).
4273 //
4274 // But some of the referents, that are in the collection set, that these
4275 // reference objects point to may not have been copied: the STW ref
4276 // processor would have seen that the reference object had already
4277 // been 'discovered' and would have skipped discovering the reference,
4278 // but would not have treated the reference object as a regular oop.
4279 // As a result the copy closure would not have been applied to the
4280 // referent object.
4281 //
4282 // We need to explicitly copy these referent objects - the references
4283 // will be processed at the end of remarking.
4284 //
4285 // We also need to do this copying before we process the reference
4286 // objects discovered by the STW ref processor in case one of these
4287 // referents points to another object which is also referenced by an
4288 // object discovered by the STW ref processor.
4289 double preserve_cm_referents_time = 0.0;
4290
4291 // To avoid spawning task when there is no work to do, check that
4292 // a concurrent cycle is active and that some references have been
4293 // discovered.
4294 if (concurrent_mark()->cmThread()->during_cycle() &&
4295 ref_processor_cm()->has_discovered_references()) {
4296 double preserve_cm_referents_start = os::elapsedTime();
4297 uint no_of_gc_workers = workers()->active_workers();
4298 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4299 per_thread_states,
4300 no_of_gc_workers,
4301 _task_queues);
4302 workers()->run_task(&keep_cm_referents);
4303 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4304 }
4305
4306 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4307 }
4308
4309 // Weak Reference processing during an evacuation pause (part 1).
4310 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4311 double ref_proc_start = os::elapsedTime();
4312
4313 ReferenceProcessor* rp = _ref_processor_stw;
4314 assert(rp->discovery_enabled(), "should have been enabled");
4315
4316 // Closure to test whether a referent is alive.
4317 G1STWIsAliveClosure is_alive(this);
4318
4319 // Even when parallel reference processing is enabled, the processing
4320 // of JNI refs is serial and performed serially by the current thread
4321 // rather than by a worker. The following PSS will be used for processing
4322 // JNI refs.
4323
4324 // Use only a single queue for this PSS.
4325 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4326 pss->set_ref_processor(NULL);
4327 assert(pss->queue_is_empty(), "pre-condition");
4328
4329 // Keep alive closure.
4330 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4331
4332 // Serial Complete GC closure
4333 G1STWDrainQueueClosure drain_queue(this, pss);
4334
4335 // Setup the soft refs policy...
4336 rp->setup_policy(false);
4337
4338 ReferenceProcessorStats stats;
4339 if (!rp->processing_is_mt()) {
4340 // Serial reference processing...
4341 stats = rp->process_discovered_references(&is_alive,
4342 &keep_alive,
4343 &drain_queue,
4344 NULL,
4345 _gc_timer_stw);
4346 } else {
4347 uint no_of_gc_workers = workers()->active_workers();
4348
4349 // Parallel reference processing
4350 assert(no_of_gc_workers <= rp->max_num_q(),
4351 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4352 no_of_gc_workers, rp->max_num_q());
4353
4354 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4355 stats = rp->process_discovered_references(&is_alive,
4356 &keep_alive,
4357 &drain_queue,
4358 &par_task_executor,
4359 _gc_timer_stw);
4360 }
4361
4362 _gc_tracer_stw->report_gc_reference_stats(stats);
4363
4364 // We have completed copying any necessary live referent objects.
4365 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4366
4367 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4368 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4369 }
4370
4371 // Weak Reference processing during an evacuation pause (part 2).
4372 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4373 double ref_enq_start = os::elapsedTime();
4374
4375 ReferenceProcessor* rp = _ref_processor_stw;
4376 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4377
4378 // Now enqueue any remaining on the discovered lists on to
4379 // the pending list.
4380 if (!rp->processing_is_mt()) {
4381 // Serial reference processing...
4382 rp->enqueue_discovered_references();
4383 } else {
4384 // Parallel reference enqueueing
4385
4386 uint n_workers = workers()->active_workers();
4387
4388 assert(n_workers <= rp->max_num_q(),
4389 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4390 n_workers, rp->max_num_q());
4391
4392 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4393 rp->enqueue_discovered_references(&par_task_executor);
4394 }
4395
4396 rp->verify_no_references_recorded();
4397 assert(!rp->discovery_enabled(), "should have been disabled");
4398
4399 // FIXME
4400 // CM's reference processing also cleans up the string and symbol tables.
4401 // Should we do that here also? We could, but it is a serial operation
4402 // and could significantly increase the pause time.
4403
4404 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4405 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4406 }
4407
4408 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4409 double merge_pss_time_start = os::elapsedTime();
4410 per_thread_states->flush();
4411 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4412 }
4413
4414 void G1CollectedHeap::pre_evacuate_collection_set() {
4415 _expand_heap_after_alloc_failure = true;
4416 _evacuation_failed = false;
4417
4418 // Disable the hot card cache.
4419 _hot_card_cache->reset_hot_cache_claimed_index();
4420 _hot_card_cache->set_use_cache(false);
4421
4422 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4423 _preserved_marks_set.assert_empty();
4424
4425 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4426
4427 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4428 if (collector_state()->during_initial_mark_pause()) {
4429 double start_clear_claimed_marks = os::elapsedTime();
4430
4431 ClassLoaderDataGraph::clear_claimed_marks();
4432
4433 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4434 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4435 }
4436 }
4437
4438 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4439 // Should G1EvacuationFailureALot be in effect for this GC?
4440 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4441
4442 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4443
4444 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4445
4446 double start_par_time_sec = os::elapsedTime();
4447 double end_par_time_sec;
4448
4449 {
4450 const uint n_workers = workers()->active_workers();
4451 G1RootProcessor root_processor(this, n_workers);
4452 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4453
4454 print_termination_stats_hdr();
4455
4456 workers()->run_task(&g1_par_task);
4457 end_par_time_sec = os::elapsedTime();
4458
4459 // Closing the inner scope will execute the destructor
4460 // for the G1RootProcessor object. We record the current
4461 // elapsed time before closing the scope so that time
4462 // taken for the destructor is NOT included in the
4463 // reported parallel time.
4464 }
4465
4466 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4467 phase_times->record_par_time(par_time_ms);
4468
4469 double code_root_fixup_time_ms =
4470 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4471 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4472 }
4473
4474 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4475 // Process any discovered reference objects - we have
4476 // to do this _before_ we retire the GC alloc regions
4477 // as we may have to copy some 'reachable' referent
4478 // objects (and their reachable sub-graphs) that were
4479 // not copied during the pause.
4480 if (g1_policy()->should_process_references()) {
4481 preserve_cm_referents(per_thread_states);
4482 process_discovered_references(per_thread_states);
4483 } else {
4484 ref_processor_stw()->verify_no_references_recorded();
4485 process_weak_jni_handles();
4486 }
4487
4488 if (G1StringDedup::is_enabled()) {
4489 double fixup_start = os::elapsedTime();
4490
4491 G1STWIsAliveClosure is_alive(this);
4492 G1KeepAliveClosure keep_alive(this);
4493 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4494
4495 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4496 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4497 }
4498
4499 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4500
4501 if (evacuation_failed()) {
4502 restore_after_evac_failure();
4503
4504 // Reset the G1EvacuationFailureALot counters and flags
4505 // Note: the values are reset only when an actual
4506 // evacuation failure occurs.
4507 NOT_PRODUCT(reset_evacuation_should_fail();)
4508 }
4509
4510 _preserved_marks_set.assert_empty();
4511
4512 // Enqueue any remaining references remaining on the STW
4513 // reference processor's discovered lists. We need to do
4514 // this after the card table is cleaned (and verified) as
4515 // the act of enqueueing entries on to the pending list
4516 // will log these updates (and dirty their associated
4517 // cards). We need these updates logged to update any
4518 // RSets.
4519 if (g1_policy()->should_process_references()) {
4520 enqueue_discovered_references(per_thread_states);
4521 } else {
4522 g1_policy()->phase_times()->record_ref_enq_time(0);
4523 }
4524
4525 _allocator->release_gc_alloc_regions(evacuation_info);
4526
4527 merge_per_thread_state_info(per_thread_states);
4528
4529 // Reset and re-enable the hot card cache.
4530 // Note the counts for the cards in the regions in the
4531 // collection set are reset when the collection set is freed.
4532 _hot_card_cache->reset_hot_cache();
4533 _hot_card_cache->set_use_cache(true);
4534
4535 purge_code_root_memory();
4536
4537 redirty_logged_cards();
4538 #if defined(COMPILER2) || INCLUDE_JVMCI
4539 double start = os::elapsedTime();
4540 DerivedPointerTable::update_pointers();
4541 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4542 #endif
4543 g1_policy()->print_age_table();
4544 }
4545
4546 void G1CollectedHeap::record_obj_copy_mem_stats() {
4547 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4548
4549 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4550 create_g1_evac_summary(&_old_evac_stats));
4551 }
4552
4553 void G1CollectedHeap::free_region(HeapRegion* hr,
4554 FreeRegionList* free_list,
4555 bool skip_remset,
4556 bool skip_hot_card_cache,
4557 bool locked) {
4558 assert(!hr->is_free(), "the region should not be free");
4559 assert(!hr->is_empty(), "the region should not be empty");
4560 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4561 assert(free_list != NULL, "pre-condition");
4562
4563 if (G1VerifyBitmaps) {
4564 MemRegion mr(hr->bottom(), hr->end());
4565 concurrent_mark()->clearRangePrevBitmap(mr);
4566 }
4567
4568 // Clear the card counts for this region.
4569 // Note: we only need to do this if the region is not young
4570 // (since we don't refine cards in young regions).
4571 if (!skip_hot_card_cache && !hr->is_young()) {
4572 _hot_card_cache->reset_card_counts(hr);
4573 }
4574 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4575 free_list->add_ordered(hr);
4576 }
4577
4578 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4579 FreeRegionList* free_list,
4580 bool skip_remset) {
4581 assert(hr->is_humongous(), "this is only for humongous regions");
4582 assert(free_list != NULL, "pre-condition");
4583 hr->clear_humongous();
4584 free_region(hr, free_list, skip_remset);
4585 }
4586
4587 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4588 const uint humongous_regions_removed) {
4589 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4590 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4591 _old_set.bulk_remove(old_regions_removed);
4592 _humongous_set.bulk_remove(humongous_regions_removed);
4593 }
4594
4595 }
4596
4597 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4598 assert(list != NULL, "list can't be null");
4599 if (!list->is_empty()) {
4600 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4601 _hrm.insert_list_into_free_list(list);
4602 }
4603 }
4604
4605 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4606 decrease_used(bytes);
4607 }
4608
4609 class G1ParScrubRemSetTask: public AbstractGangTask {
4610 protected:
4611 G1RemSet* _g1rs;
4612 HeapRegionClaimer _hrclaimer;
4613
4614 public:
4615 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4616 AbstractGangTask("G1 ScrubRS"),
4617 _g1rs(g1_rs),
4618 _hrclaimer(num_workers) {
4619 }
4620
4621 void work(uint worker_id) {
4622 _g1rs->scrub(worker_id, &_hrclaimer);
4623 }
4624 };
4625
4626 void G1CollectedHeap::scrub_rem_set() {
4627 uint num_workers = workers()->active_workers();
4628 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4629 workers()->run_task(&g1_par_scrub_rs_task);
4630 }
4631
4632 class G1FreeCollectionSetTask : public AbstractGangTask {
4633 private:
4634
4635 // Closure applied to all regions in the collection set to do work that needs to
4636 // be done serially in a single thread.
4637 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4638 private:
4639 EvacuationInfo* _evacuation_info;
4640 const size_t* _surviving_young_words;
4641
4642 // Bytes used in successfully evacuated regions before the evacuation.
4643 size_t _before_used_bytes;
4644 // Bytes used in unsucessfully evacuated regions before the evacuation
4645 size_t _after_used_bytes;
4646
4647 size_t _bytes_allocated_in_old_since_last_gc;
4648
4649 size_t _failure_used_words;
4650 size_t _failure_waste_words;
4651
4652 FreeRegionList _local_free_list;
4653 public:
4654 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4655 HeapRegionClosure(),
4656 _evacuation_info(evacuation_info),
4657 _surviving_young_words(surviving_young_words),
4658 _before_used_bytes(0),
4659 _after_used_bytes(0),
4660 _bytes_allocated_in_old_since_last_gc(0),
4661 _failure_used_words(0),
4662 _failure_waste_words(0),
4663 _local_free_list("Local Region List for CSet Freeing") {
4664 }
4665
4666 virtual bool doHeapRegion(HeapRegion* r) {
4667 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4668
4669 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4670 g1h->clear_in_cset(r);
4671
4672 if (r->is_young()) {
4673 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4674 "Young index %d is wrong for region %u of type %s with %u young regions",
4675 r->young_index_in_cset(),
4676 r->hrm_index(),
4677 r->get_type_str(),
4678 g1h->collection_set()->young_region_length());
4679 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4680 r->record_surv_words_in_group(words_survived);
4681 }
4682
4683 if (!r->evacuation_failed()) {
4684 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4685 _before_used_bytes += r->used();
4686 g1h->free_region(r,
4687 &_local_free_list,
4688 true, /* skip_remset */
4689 true, /* skip_hot_card_cache */
4690 true /* locked */);
4691 } else {
4692 r->uninstall_surv_rate_group();
4693 r->set_young_index_in_cset(-1);
4694 r->set_evacuation_failed(false);
4695 // When moving a young gen region to old gen, we "allocate" that whole region
4696 // there. This is in addition to any already evacuated objects. Notify the
4697 // policy about that.
4698 // Old gen regions do not cause an additional allocation: both the objects
4699 // still in the region and the ones already moved are accounted for elsewhere.
4700 if (r->is_young()) {
4701 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4702 }
4703 // The region is now considered to be old.
4704 r->set_old();
4705 // Do some allocation statistics accounting. Regions that failed evacuation
4706 // are always made old, so there is no need to update anything in the young
4707 // gen statistics, but we need to update old gen statistics.
4708 size_t used_words = r->marked_bytes() / HeapWordSize;
4709
4710 _failure_used_words += used_words;
4711 _failure_waste_words += HeapRegion::GrainWords - used_words;
4712
4713 g1h->old_set_add(r);
4714 _after_used_bytes += r->used();
4715 }
4716 return false;
4717 }
4718
4719 void complete_work() {
4720 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4721
4722 _evacuation_info->set_regions_freed(_local_free_list.length());
4723 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4724
4725 g1h->prepend_to_freelist(&_local_free_list);
4726 g1h->decrement_summary_bytes(_before_used_bytes);
4727
4728 G1Policy* policy = g1h->g1_policy();
4729 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4730
4731 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4732 }
4733 };
4734
4735 G1CollectionSet* _collection_set;
4736 G1SerialFreeCollectionSetClosure _cl;
4737 const size_t* _surviving_young_words;
4738
4739 size_t _rs_lengths;
4740
4741 volatile jint _serial_work_claim;
4742
4743 struct WorkItem {
4744 uint region_idx;
4745 bool is_young;
4746 bool evacuation_failed;
4747
4748 WorkItem(HeapRegion* r) {
4749 region_idx = r->hrm_index();
4750 is_young = r->is_young();
4751 evacuation_failed = r->evacuation_failed();
4752 }
4753 };
4754
4755 volatile size_t _parallel_work_claim;
4756 size_t _num_work_items;
4757 WorkItem* _work_items;
4758
4759 void do_serial_work() {
4760 // Need to grab the lock to be allowed to modify the old region list.
4761 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4762 _collection_set->iterate(&_cl);
4763 }
4764
4765 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4766 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4767
4768 HeapRegion* r = g1h->region_at(region_idx);
4769 assert(!g1h->is_on_master_free_list(r), "sanity");
4770
4771 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4772
4773 if (!is_young) {
4774 g1h->_hot_card_cache->reset_card_counts(r);
4775 }
4776
4777 if (!evacuation_failed) {
4778 r->rem_set()->clear_locked();
4779 }
4780 }
4781
4782 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4783 private:
4784 size_t _cur_idx;
4785 WorkItem* _work_items;
4786 public:
4787 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4788
4789 virtual bool doHeapRegion(HeapRegion* r) {
4790 _work_items[_cur_idx++] = WorkItem(r);
4791 return false;
4792 }
4793 };
4794
4795 void prepare_work() {
4796 G1PrepareFreeCollectionSetClosure cl(_work_items);
4797 _collection_set->iterate(&cl);
4798 }
4799
4800 void complete_work() {
4801 _cl.complete_work();
4802
4803 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4804 policy->record_max_rs_lengths(_rs_lengths);
4805 policy->cset_regions_freed();
4806 }
4807 public:
4808 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4809 AbstractGangTask("G1 Free Collection Set"),
4810 _cl(evacuation_info, surviving_young_words),
4811 _collection_set(collection_set),
4812 _surviving_young_words(surviving_young_words),
4813 _serial_work_claim(0),
4814 _rs_lengths(0),
4815 _parallel_work_claim(0),
4816 _num_work_items(collection_set->region_length()),
4817 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4818 prepare_work();
4819 }
4820
4821 ~G1FreeCollectionSetTask() {
4822 complete_work();
4823 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4824 }
4825
4826 // Chunk size for work distribution. The chosen value has been determined experimentally
4827 // to be a good tradeoff between overhead and achievable parallelism.
4828 static uint chunk_size() { return 32; }
4829
4830 virtual void work(uint worker_id) {
4831 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4832
4833 // Claim serial work.
4834 if (_serial_work_claim == 0) {
4835 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4836 if (value == 0) {
4837 double serial_time = os::elapsedTime();
4838 do_serial_work();
4839 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4840 }
4841 }
4842
4843 // Start parallel work.
4844 double young_time = 0.0;
4845 bool has_young_time = false;
4846 double non_young_time = 0.0;
4847 bool has_non_young_time = false;
4848
4849 while (true) {
4850 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4851 size_t cur = end - chunk_size();
4852
4853 if (cur >= _num_work_items) {
4854 break;
4855 }
4856
4857 double start_time = os::elapsedTime();
4858
4859 end = MIN2(end, _num_work_items);
4860
4861 for (; cur < end; cur++) {
4862 bool is_young = _work_items[cur].is_young;
4863
4864 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4865
4866 double end_time = os::elapsedTime();
4867 double time_taken = end_time - start_time;
4868 if (is_young) {
4869 young_time += time_taken;
4870 has_young_time = true;
4871 } else {
4872 non_young_time += time_taken;
4873 has_non_young_time = true;
4874 }
4875 start_time = end_time;
4876 }
4877 }
4878
4879 if (has_young_time) {
4880 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4881 }
4882 if (has_non_young_time) {
4883 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4884 }
4885 }
4886 };
4887
4888 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4889 _eden.clear();
4890
4891 double free_cset_start_time = os::elapsedTime();
4892
4893 {
4894 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4895 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4896
4897 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4898
4899 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4900 cl.name(),
4901 num_workers,
4902 _collection_set.region_length());
4903 workers()->run_task(&cl, num_workers);
4904 }
4905 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4906
4907 collection_set->clear();
4908 }
4909
4910 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4911 private:
4912 FreeRegionList* _free_region_list;
4913 HeapRegionSet* _proxy_set;
4914 uint _humongous_objects_reclaimed;
4915 uint _humongous_regions_reclaimed;
4916 size_t _freed_bytes;
4917 public:
4918
4919 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4920 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4921 }
4922
4923 virtual bool doHeapRegion(HeapRegion* r) {
4924 if (!r->is_starts_humongous()) {
4925 return false;
4926 }
4927
4928 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4929
4930 oop obj = (oop)r->bottom();
4931 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4932
4933 // The following checks whether the humongous object is live are sufficient.
4934 // The main additional check (in addition to having a reference from the roots
4935 // or the young gen) is whether the humongous object has a remembered set entry.
4936 //
4937 // A humongous object cannot be live if there is no remembered set for it
4938 // because:
4939 // - there can be no references from within humongous starts regions referencing
4940 // the object because we never allocate other objects into them.
4941 // (I.e. there are no intra-region references that may be missed by the
4942 // remembered set)
4943 // - as soon there is a remembered set entry to the humongous starts region
4944 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4945 // until the end of a concurrent mark.
4946 //
4947 // It is not required to check whether the object has been found dead by marking
4948 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4949 // all objects allocated during that time are considered live.
4950 // SATB marking is even more conservative than the remembered set.
4951 // So if at this point in the collection there is no remembered set entry,
4952 // nobody has a reference to it.
4953 // At the start of collection we flush all refinement logs, and remembered sets
4954 // are completely up-to-date wrt to references to the humongous object.
4955 //
4956 // Other implementation considerations:
4957 // - never consider object arrays at this time because they would pose
4958 // considerable effort for cleaning up the the remembered sets. This is
4959 // required because stale remembered sets might reference locations that
4960 // are currently allocated into.
4961 uint region_idx = r->hrm_index();
4962 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4963 !r->rem_set()->is_empty()) {
4964 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",
4965 region_idx,
4966 (size_t)obj->size() * HeapWordSize,
4967 p2i(r->bottom()),
4968 r->rem_set()->occupied(),
4969 r->rem_set()->strong_code_roots_list_length(),
4970 next_bitmap->isMarked(r->bottom()),
4971 g1h->is_humongous_reclaim_candidate(region_idx),
4972 obj->is_typeArray()
4973 );
4974 return false;
4975 }
4976
4977 guarantee(obj->is_typeArray(),
4978 "Only eagerly reclaiming type arrays is supported, but the object "
4979 PTR_FORMAT " is not.", p2i(r->bottom()));
4980
4981 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",
4982 region_idx,
4983 (size_t)obj->size() * HeapWordSize,
4984 p2i(r->bottom()),
4985 r->rem_set()->occupied(),
4986 r->rem_set()->strong_code_roots_list_length(),
4987 next_bitmap->isMarked(r->bottom()),
4988 g1h->is_humongous_reclaim_candidate(region_idx),
4989 obj->is_typeArray()
4990 );
4991
4992 // Need to clear mark bit of the humongous object if already set.
4993 if (next_bitmap->isMarked(r->bottom())) {
4994 next_bitmap->clear(r->bottom());
4995 }
4996 _humongous_objects_reclaimed++;
4997 do {
4998 HeapRegion* next = g1h->next_region_in_humongous(r);
4999 _freed_bytes += r->used();
5000 r->set_containing_set(NULL);
5001 _humongous_regions_reclaimed++;
5002 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
5003 r = next;
5004 } while (r != NULL);
5005
5006 return false;
5007 }
5008
5009 uint humongous_objects_reclaimed() {
5010 return _humongous_objects_reclaimed;
5011 }
5012
5013 uint humongous_regions_reclaimed() {
5014 return _humongous_regions_reclaimed;
5015 }
5016
5017 size_t bytes_freed() const {
5018 return _freed_bytes;
5019 }
5020 };
5021
5022 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5023 assert_at_safepoint(true);
5024
5025 if (!G1EagerReclaimHumongousObjects ||
5026 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5027 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5028 return;
5029 }
5030
5031 double start_time = os::elapsedTime();
5032
5033 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5034
5035 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5036 heap_region_iterate(&cl);
5037
5038 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
5039
5040 G1HRPrinter* hrp = hr_printer();
5041 if (hrp->is_active()) {
5042 FreeRegionListIterator iter(&local_cleanup_list);
5043 while (iter.more_available()) {
5044 HeapRegion* hr = iter.get_next();
5045 hrp->cleanup(hr);
5046 }
5047 }
5048
5049 prepend_to_freelist(&local_cleanup_list);
5050 decrement_summary_bytes(cl.bytes_freed());
5051
5052 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5053 cl.humongous_objects_reclaimed());
5054 }
5055
5056 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5057 public:
5058 virtual bool doHeapRegion(HeapRegion* r) {
5059 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5060 G1CollectedHeap::heap()->clear_in_cset(r);
5061 r->set_young_index_in_cset(-1);
5062 return false;
5063 }
5064 };
5065
5066 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5067 G1AbandonCollectionSetClosure cl;
5068 collection_set->iterate(&cl);
5069
5070 collection_set->clear();
5071 collection_set->stop_incremental_building();
5072 }
5073
5074 void G1CollectedHeap::set_free_regions_coming() {
5075 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5076
5077 assert(!free_regions_coming(), "pre-condition");
5078 _free_regions_coming = true;
5079 }
5080
5081 void G1CollectedHeap::reset_free_regions_coming() {
5082 assert(free_regions_coming(), "pre-condition");
5083
5084 {
5085 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5086 _free_regions_coming = false;
5087 SecondaryFreeList_lock->notify_all();
5088 }
5089
5090 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5091 }
5092
5093 void G1CollectedHeap::wait_while_free_regions_coming() {
5094 // Most of the time we won't have to wait, so let's do a quick test
5095 // first before we take the lock.
5096 if (!free_regions_coming()) {
5097 return;
5098 }
5099
5100 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5101
5102 {
5103 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5104 while (free_regions_coming()) {
5105 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5106 }
5107 }
5108
5109 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5110 }
5111
5112 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5113 return _allocator->is_retained_old_region(hr);
5114 }
5115
5116 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5117 _eden.add(hr);
5118 _g1_policy->set_region_eden(hr);
5119 }
5120
5121 #ifdef ASSERT
5122
5123 class NoYoungRegionsClosure: public HeapRegionClosure {
5124 private:
5125 bool _success;
5126 public:
5127 NoYoungRegionsClosure() : _success(true) { }
5128 bool doHeapRegion(HeapRegion* r) {
5129 if (r->is_young()) {
5130 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5131 p2i(r->bottom()), p2i(r->end()));
5132 _success = false;
5133 }
5134 return false;
5135 }
5136 bool success() { return _success; }
5137 };
5138
5139 bool G1CollectedHeap::check_young_list_empty() {
5140 bool ret = (young_regions_count() == 0);
5141
5142 NoYoungRegionsClosure closure;
5143 heap_region_iterate(&closure);
5144 ret = ret && closure.success();
5145
5146 return ret;
5147 }
5148
5149 #endif // ASSERT
5150
5151 class TearDownRegionSetsClosure : public HeapRegionClosure {
5152 private:
5153 HeapRegionSet *_old_set;
5154
5155 public:
5156 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5157
5158 bool doHeapRegion(HeapRegion* r) {
5159 if (r->is_old()) {
5160 _old_set->remove(r);
5161 } else if(r->is_young()) {
5162 r->uninstall_surv_rate_group();
5163 } else {
5164 // We ignore free regions, we'll empty the free list afterwards.
5165 // We ignore humongous regions, we're not tearing down the
5166 // humongous regions set.
5167 assert(r->is_free() || r->is_humongous(),
5168 "it cannot be another type");
5169 }
5170 return false;
5171 }
5172
5173 ~TearDownRegionSetsClosure() {
5174 assert(_old_set->is_empty(), "post-condition");
5175 }
5176 };
5177
5178 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5179 assert_at_safepoint(true /* should_be_vm_thread */);
5180
5181 if (!free_list_only) {
5182 TearDownRegionSetsClosure cl(&_old_set);
5183 heap_region_iterate(&cl);
5184
5185 // Note that emptying the _young_list is postponed and instead done as
5186 // the first step when rebuilding the regions sets again. The reason for
5187 // this is that during a full GC string deduplication needs to know if
5188 // a collected region was young or old when the full GC was initiated.
5189 }
5190 _hrm.remove_all_free_regions();
5191 }
5192
5193 void G1CollectedHeap::increase_used(size_t bytes) {
5194 _summary_bytes_used += bytes;
5195 }
5196
5197 void G1CollectedHeap::decrease_used(size_t bytes) {
5198 assert(_summary_bytes_used >= bytes,
5199 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5200 _summary_bytes_used, bytes);
5201 _summary_bytes_used -= bytes;
5202 }
5203
5204 void G1CollectedHeap::set_used(size_t bytes) {
5205 _summary_bytes_used = bytes;
5206 }
5207
5208 class RebuildRegionSetsClosure : public HeapRegionClosure {
5209 private:
5210 bool _free_list_only;
5211 HeapRegionSet* _old_set;
5212 HeapRegionManager* _hrm;
5213 size_t _total_used;
5214
5215 public:
5216 RebuildRegionSetsClosure(bool free_list_only,
5217 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5218 _free_list_only(free_list_only),
5219 _old_set(old_set), _hrm(hrm), _total_used(0) {
5220 assert(_hrm->num_free_regions() == 0, "pre-condition");
5221 if (!free_list_only) {
5222 assert(_old_set->is_empty(), "pre-condition");
5223 }
5224 }
5225
5226 bool doHeapRegion(HeapRegion* r) {
5227 if (r->is_empty()) {
5228 // Add free regions to the free list
5229 r->set_free();
5230 r->set_allocation_context(AllocationContext::system());
5231 _hrm->insert_into_free_list(r);
5232 } else if (!_free_list_only) {
5233
5234 if (r->is_humongous()) {
5235 // We ignore humongous regions. We left the humongous set unchanged.
5236 } else {
5237 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5238 // We now consider all regions old, so register as such. Leave
5239 // archive regions set that way, however, while still adding
5240 // them to the old set.
5241 if (!r->is_archive()) {
5242 r->set_old();
5243 }
5244 _old_set->add(r);
5245 }
5246 _total_used += r->used();
5247 }
5248
5249 return false;
5250 }
5251
5252 size_t total_used() {
5253 return _total_used;
5254 }
5255 };
5256
5257 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5258 assert_at_safepoint(true /* should_be_vm_thread */);
5259
5260 if (!free_list_only) {
5261 _eden.clear();
5262 _survivor.clear();
5263 }
5264
5265 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5266 heap_region_iterate(&cl);
5267
5268 if (!free_list_only) {
5269 set_used(cl.total_used());
5270 if (_archive_allocator != NULL) {
5271 _archive_allocator->clear_used();
5272 }
5273 }
5274 assert(used_unlocked() == recalculate_used(),
5275 "inconsistent used_unlocked(), "
5276 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5277 used_unlocked(), recalculate_used());
5278 }
5279
5280 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5281 _refine_cte_cl->set_concurrent(concurrent);
5282 }
5283
5284 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5285 HeapRegion* hr = heap_region_containing(p);
5286 return hr->is_in(p);
5287 }
5288
5289 // Methods for the mutator alloc region
5290
5291 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5292 bool force) {
5293 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5294 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5295 if (force || should_allocate) {
5296 HeapRegion* new_alloc_region = new_region(word_size,
5297 false /* is_old */,
5298 false /* do_expand */);
5299 if (new_alloc_region != NULL) {
5300 set_region_short_lived_locked(new_alloc_region);
5301 _hr_printer.alloc(new_alloc_region, !should_allocate);
5302 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5303 return new_alloc_region;
5304 }
5305 }
5306 return NULL;
5307 }
5308
5309 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5310 size_t allocated_bytes) {
5311 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5312 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5313
5314 collection_set()->add_eden_region(alloc_region);
5315 increase_used(allocated_bytes);
5316 _hr_printer.retire(alloc_region);
5317 // We update the eden sizes here, when the region is retired,
5318 // instead of when it's allocated, since this is the point that its
5319 // used space has been recored in _summary_bytes_used.
5320 g1mm()->update_eden_size();
5321 }
5322
5323 // Methods for the GC alloc regions
5324
5325 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5326 if (dest.is_old()) {
5327 return true;
5328 } else {
5329 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5330 }
5331 }
5332
5333 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5334 assert(FreeList_lock->owned_by_self(), "pre-condition");
5335
5336 if (!has_more_regions(dest)) {
5337 return NULL;
5338 }
5339
5340 const bool is_survivor = dest.is_young();
5341
5342 HeapRegion* new_alloc_region = new_region(word_size,
5343 !is_survivor,
5344 true /* do_expand */);
5345 if (new_alloc_region != NULL) {
5346 // We really only need to do this for old regions given that we
5347 // should never scan survivors. But it doesn't hurt to do it
5348 // for survivors too.
5349 new_alloc_region->record_timestamp();
5350 if (is_survivor) {
5351 new_alloc_region->set_survivor();
5352 _survivor.add(new_alloc_region);
5353 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5354 } else {
5355 new_alloc_region->set_old();
5356 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5357 }
5358 _hr_printer.alloc(new_alloc_region);
5359 bool during_im = collector_state()->during_initial_mark_pause();
5360 new_alloc_region->note_start_of_copying(during_im);
5361 return new_alloc_region;
5362 }
5363 return NULL;
5364 }
5365
5366 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5367 size_t allocated_bytes,
5368 InCSetState dest) {
5369 bool during_im = collector_state()->during_initial_mark_pause();
5370 alloc_region->note_end_of_copying(during_im);
5371 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5372 if (dest.is_old()) {
5373 _old_set.add(alloc_region);
5374 }
5375 _hr_printer.retire(alloc_region);
5376 }
5377
5378 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5379 bool expanded = false;
5380 uint index = _hrm.find_highest_free(&expanded);
5381
5382 if (index != G1_NO_HRM_INDEX) {
5383 if (expanded) {
5384 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5385 HeapRegion::GrainWords * HeapWordSize);
5386 }
5387 _hrm.allocate_free_regions_starting_at(index, 1);
5388 return region_at(index);
5389 }
5390 return NULL;
5391 }
5392
5393 // Optimized nmethod scanning
5394
5395 class RegisterNMethodOopClosure: public OopClosure {
5396 G1CollectedHeap* _g1h;
5397 nmethod* _nm;
5398
5399 template <class T> void do_oop_work(T* p) {
5400 T heap_oop = oopDesc::load_heap_oop(p);
5401 if (!oopDesc::is_null(heap_oop)) {
5402 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5403 HeapRegion* hr = _g1h->heap_region_containing(obj);
5404 assert(!hr->is_continues_humongous(),
5405 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5406 " starting at " HR_FORMAT,
5407 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5408
5409 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5410 hr->add_strong_code_root_locked(_nm);
5411 }
5412 }
5413
5414 public:
5415 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5416 _g1h(g1h), _nm(nm) {}
5417
5418 void do_oop(oop* p) { do_oop_work(p); }
5419 void do_oop(narrowOop* p) { do_oop_work(p); }
5420 };
5421
5422 class UnregisterNMethodOopClosure: public OopClosure {
5423 G1CollectedHeap* _g1h;
5424 nmethod* _nm;
5425
5426 template <class T> void do_oop_work(T* p) {
5427 T heap_oop = oopDesc::load_heap_oop(p);
5428 if (!oopDesc::is_null(heap_oop)) {
5429 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5430 HeapRegion* hr = _g1h->heap_region_containing(obj);
5431 assert(!hr->is_continues_humongous(),
5432 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5433 " starting at " HR_FORMAT,
5434 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5435
5436 hr->remove_strong_code_root(_nm);
5437 }
5438 }
5439
5440 public:
5441 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5442 _g1h(g1h), _nm(nm) {}
5443
5444 void do_oop(oop* p) { do_oop_work(p); }
5445 void do_oop(narrowOop* p) { do_oop_work(p); }
5446 };
5447
5448 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5449 CollectedHeap::register_nmethod(nm);
5450
5451 guarantee(nm != NULL, "sanity");
5452 RegisterNMethodOopClosure reg_cl(this, nm);
5453 nm->oops_do(®_cl);
5454 }
5455
5456 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5457 CollectedHeap::unregister_nmethod(nm);
5458
5459 guarantee(nm != NULL, "sanity");
5460 UnregisterNMethodOopClosure reg_cl(this, nm);
5461 nm->oops_do(®_cl, true);
5462 }
5463
5464 void G1CollectedHeap::purge_code_root_memory() {
5465 double purge_start = os::elapsedTime();
5466 G1CodeRootSet::purge();
5467 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5468 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5469 }
5470
5471 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5472 G1CollectedHeap* _g1h;
5473
5474 public:
5475 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5476 _g1h(g1h) {}
5477
5478 void do_code_blob(CodeBlob* cb) {
5479 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5480 if (nm == NULL) {
5481 return;
5482 }
5483
5484 if (ScavengeRootsInCode) {
5485 _g1h->register_nmethod(nm);
5486 }
5487 }
5488 };
5489
5490 void G1CollectedHeap::rebuild_strong_code_roots() {
5491 RebuildStrongCodeRootClosure blob_cl(this);
5492 CodeCache::blobs_do(&blob_cl);
5493 }