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 "runtime/atomic.hpp"
78 #include "runtime/init.hpp"
79 #include "runtime/orderAccess.inline.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "utilities/globalDefinitions.hpp"
82 #include "utilities/stack.inline.hpp"
83
84 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
85
86 // INVARIANTS/NOTES
87 //
88 // All allocation activity covered by the G1CollectedHeap interface is
89 // serialized by acquiring the HeapLock. This happens in mem_allocate
90 // and allocate_new_tlab, which are the "entry" points to the
91 // allocation code from the rest of the JVM. (Note that this does not
92 // apply to TLAB allocation, which is not part of this interface: it
93 // is done by clients of this interface.)
94
95 // Local to this file.
96
97 class RefineCardTableEntryClosure: public CardTableEntryClosure {
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure() : _concurrent(true) { }
101
102 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
103 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, NULL);
104 // This path is executed by the concurrent refine or mutator threads,
105 // concurrently, and so we do not care if card_ptr contains references
106 // that point into the collection set.
107 assert(!oops_into_cset, "should be");
108
109 if (_concurrent && SuspendibleThreadSet::should_yield()) {
110 // Caller will actually yield.
111 return false;
112 }
113 // Otherwise, we finished successfully; return true.
114 return true;
115 }
116
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
122 private:
123 size_t _num_dirtied;
124 G1CollectedHeap* _g1h;
125 G1SATBCardTableLoggingModRefBS* _g1_bs;
126
127 HeapRegion* region_for_card(jbyte* card_ptr) const {
128 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
129 }
130
131 bool will_become_free(HeapRegion* hr) const {
132 // A region will be freed by free_collection_set if the region is in the
133 // collection set and has not had an evacuation failure.
134 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
135 }
136
137 public:
138 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
139 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
140
141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
142 HeapRegion* hr = region_for_card(card_ptr);
143
144 // Should only dirty cards in regions that won't be freed.
145 if (!will_become_free(hr)) {
146 *card_ptr = CardTableModRefBS::dirty_card_val();
147 _num_dirtied++;
148 }
149
150 return true;
151 }
152
153 size_t num_dirtied() const { return _num_dirtied; }
154 };
155
156
157 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
158 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
159 }
160
161 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
162 // The from card cache is not the memory that is actually committed. So we cannot
163 // take advantage of the zero_filled parameter.
164 reset_from_card_cache(start_idx, num_regions);
165 }
166
167 // Returns true if the reference points to an object that
168 // can move in an incremental collection.
169 bool G1CollectedHeap::is_scavengable(const void* p) {
170 HeapRegion* hr = heap_region_containing(p);
171 return !hr->is_pinned();
172 }
173
174 // Private methods.
175
176 HeapRegion*
177 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
178 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
179 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
180 if (!_secondary_free_list.is_empty()) {
181 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
182 "secondary_free_list has %u entries",
183 _secondary_free_list.length());
184 // It looks as if there are free regions available on the
185 // secondary_free_list. Let's move them to the free_list and try
186 // again to allocate from it.
187 append_secondary_free_list();
188
189 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
190 "empty we should have moved at least one entry to the free_list");
191 HeapRegion* res = _hrm.allocate_free_region(is_old);
192 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
193 "allocated " HR_FORMAT " from secondary_free_list",
194 HR_FORMAT_PARAMS(res));
195 return res;
196 }
197
198 // Wait here until we get notified either when (a) there are no
199 // more free regions coming or (b) some regions have been moved on
200 // the secondary_free_list.
201 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
202 }
203
204 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
205 "could not allocate from secondary_free_list");
206 return NULL;
207 }
208
209 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
210 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
211 "the only time we use this to allocate a humongous region is "
212 "when we are allocating a single humongous region");
213
214 HeapRegion* res;
215 if (G1StressConcRegionFreeing) {
216 if (!_secondary_free_list.is_empty()) {
217 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
218 "forced to look at the secondary_free_list");
219 res = new_region_try_secondary_free_list(is_old);
220 if (res != NULL) {
221 return res;
222 }
223 }
224 }
225
226 res = _hrm.allocate_free_region(is_old);
227
228 if (res == NULL) {
229 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
230 "res == NULL, trying the secondary_free_list");
231 res = new_region_try_secondary_free_list(is_old);
232 }
233 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
234 // Currently, only attempts to allocate GC alloc regions set
235 // do_expand to true. So, we should only reach here during a
236 // safepoint. If this assumption changes we might have to
237 // reconsider the use of _expand_heap_after_alloc_failure.
238 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
239
240 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
241 word_size * HeapWordSize);
242
243 if (expand(word_size * HeapWordSize)) {
244 // Given that expand() succeeded in expanding the heap, and we
245 // always expand the heap by an amount aligned to the heap
246 // region size, the free list should in theory not be empty.
247 // In either case allocate_free_region() will check for NULL.
248 res = _hrm.allocate_free_region(is_old);
249 } else {
250 _expand_heap_after_alloc_failure = false;
251 }
252 }
253 return res;
254 }
255
256 HeapWord*
257 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
258 uint num_regions,
259 size_t word_size,
260 AllocationContext_t context) {
261 assert(first != G1_NO_HRM_INDEX, "pre-condition");
262 assert(is_humongous(word_size), "word_size should be humongous");
263 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
264
265 // Index of last region in the series.
266 uint last = first + num_regions - 1;
267
268 // We need to initialize the region(s) we just discovered. This is
269 // a bit tricky given that it can happen concurrently with
270 // refinement threads refining cards on these regions and
271 // potentially wanting to refine the BOT as they are scanning
272 // those cards (this can happen shortly after a cleanup; see CR
273 // 6991377). So we have to set up the region(s) carefully and in
274 // a specific order.
275
276 // The word size sum of all the regions we will allocate.
277 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
278 assert(word_size <= word_size_sum, "sanity");
279
280 // This will be the "starts humongous" region.
281 HeapRegion* first_hr = region_at(first);
282 // The header of the new object will be placed at the bottom of
283 // the first region.
284 HeapWord* new_obj = first_hr->bottom();
285 // This will be the new top of the new object.
286 HeapWord* obj_top = new_obj + word_size;
287
288 // First, we need to zero the header of the space that we will be
289 // allocating. When we update top further down, some refinement
290 // threads might try to scan the region. By zeroing the header we
291 // ensure that any thread that will try to scan the region will
292 // come across the zero klass word and bail out.
293 //
294 // NOTE: It would not have been correct to have used
295 // CollectedHeap::fill_with_object() and make the space look like
296 // an int array. The thread that is doing the allocation will
297 // later update the object header to a potentially different array
298 // type and, for a very short period of time, the klass and length
299 // fields will be inconsistent. This could cause a refinement
300 // thread to calculate the object size incorrectly.
301 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
302
303 // Next, pad out the unused tail of the last region with filler
304 // objects, for improved usage accounting.
305 // How many words we use for filler objects.
306 size_t word_fill_size = word_size_sum - word_size;
307
308 // How many words memory we "waste" which cannot hold a filler object.
309 size_t words_not_fillable = 0;
310
311 if (word_fill_size >= min_fill_size()) {
312 fill_with_objects(obj_top, word_fill_size);
313 } else if (word_fill_size > 0) {
314 // We have space to fill, but we cannot fit an object there.
315 words_not_fillable = word_fill_size;
316 word_fill_size = 0;
317 }
318
319 // We will set up the first region as "starts humongous". This
320 // will also update the BOT covering all the regions to reflect
321 // that there is a single object that starts at the bottom of the
322 // first region.
323 first_hr->set_starts_humongous(obj_top, word_fill_size);
324 first_hr->set_allocation_context(context);
325 // Then, if there are any, we will set up the "continues
326 // humongous" regions.
327 HeapRegion* hr = NULL;
328 for (uint i = first + 1; i <= last; ++i) {
329 hr = region_at(i);
330 hr->set_continues_humongous(first_hr);
331 hr->set_allocation_context(context);
332 }
333
334 // Up to this point no concurrent thread would have been able to
335 // do any scanning on any region in this series. All the top
336 // fields still point to bottom, so the intersection between
337 // [bottom,top] and [card_start,card_end] will be empty. Before we
338 // update the top fields, we'll do a storestore to make sure that
339 // no thread sees the update to top before the zeroing of the
340 // object header and the BOT initialization.
341 OrderAccess::storestore();
342
343 // Now, we will update the top fields of the "continues humongous"
344 // regions except the last one.
345 for (uint i = first; i < last; ++i) {
346 hr = region_at(i);
347 hr->set_top(hr->end());
348 }
349
350 hr = region_at(last);
351 // If we cannot fit a filler object, we must set top to the end
352 // of the humongous object, otherwise we cannot iterate the heap
353 // and the BOT will not be complete.
354 hr->set_top(hr->end() - words_not_fillable);
355
356 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
357 "obj_top should be in last region");
358
359 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
360
361 assert(words_not_fillable == 0 ||
362 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
363 "Miscalculation in humongous allocation");
364
365 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
366
367 for (uint i = first; i <= last; ++i) {
368 hr = region_at(i);
369 _humongous_set.add(hr);
370 _hr_printer.alloc(hr);
371 }
372
373 return new_obj;
374 }
375
376 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
377 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
378 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
379 }
380
381 // If could fit into free regions w/o expansion, try.
382 // Otherwise, if can expand, do so.
383 // Otherwise, if using ex regions might help, try with ex given back.
384 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
385 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
386
387 _verifier->verify_region_sets_optional();
388
389 uint first = G1_NO_HRM_INDEX;
390 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
391
392 if (obj_regions == 1) {
393 // Only one region to allocate, try to use a fast path by directly allocating
394 // from the free lists. Do not try to expand here, we will potentially do that
395 // later.
396 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
397 if (hr != NULL) {
398 first = hr->hrm_index();
399 }
400 } else {
401 // We can't allocate humongous regions spanning more than one region while
402 // cleanupComplete() is running, since some of the regions we find to be
403 // empty might not yet be added to the free list. It is not straightforward
404 // to know in which list they are on so that we can remove them. We only
405 // need to do this if we need to allocate more than one region to satisfy the
406 // current humongous allocation request. If we are only allocating one region
407 // we use the one-region region allocation code (see above), that already
408 // potentially waits for regions from the secondary free list.
409 wait_while_free_regions_coming();
410 append_secondary_free_list_if_not_empty_with_lock();
411
412 // Policy: Try only empty regions (i.e. already committed first). Maybe we
413 // are lucky enough to find some.
414 first = _hrm.find_contiguous_only_empty(obj_regions);
415 if (first != G1_NO_HRM_INDEX) {
416 _hrm.allocate_free_regions_starting_at(first, obj_regions);
417 }
418 }
419
420 if (first == G1_NO_HRM_INDEX) {
421 // Policy: We could not find enough regions for the humongous object in the
422 // free list. Look through the heap to find a mix of free and uncommitted regions.
423 // If so, try expansion.
424 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
425 if (first != G1_NO_HRM_INDEX) {
426 // We found something. Make sure these regions are committed, i.e. expand
427 // the heap. Alternatively we could do a defragmentation GC.
428 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
429 word_size * HeapWordSize);
430
431 _hrm.expand_at(first, obj_regions, workers());
432 g1_policy()->record_new_heap_size(num_regions());
433
434 #ifdef ASSERT
435 for (uint i = first; i < first + obj_regions; ++i) {
436 HeapRegion* hr = region_at(i);
437 assert(hr->is_free(), "sanity");
438 assert(hr->is_empty(), "sanity");
439 assert(is_on_master_free_list(hr), "sanity");
440 }
441 #endif
442 _hrm.allocate_free_regions_starting_at(first, obj_regions);
443 } else {
444 // Policy: Potentially trigger a defragmentation GC.
445 }
446 }
447
448 HeapWord* result = NULL;
449 if (first != G1_NO_HRM_INDEX) {
450 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
451 word_size, context);
452 assert(result != NULL, "it should always return a valid result");
453
454 // A successful humongous object allocation changes the used space
455 // information of the old generation so we need to recalculate the
456 // sizes and update the jstat counters here.
457 g1mm()->update_sizes();
458 }
459
460 _verifier->verify_region_sets_optional();
461
462 return result;
463 }
464
465 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
466 assert_heap_not_locked_and_not_at_safepoint();
467 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
468
469 uint dummy_gc_count_before;
470 uint dummy_gclocker_retry_count = 0;
471 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
472 }
473
474 HeapWord*
475 G1CollectedHeap::mem_allocate(size_t word_size,
476 bool* gc_overhead_limit_was_exceeded) {
477 assert_heap_not_locked_and_not_at_safepoint();
478
479 // Loop until the allocation is satisfied, or unsatisfied after GC.
480 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
481 uint gc_count_before;
482
483 HeapWord* result = NULL;
484 if (!is_humongous(word_size)) {
485 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
486 } else {
487 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
488 }
489 if (result != NULL) {
490 return result;
491 }
492
493 // Create the garbage collection operation...
494 VM_G1CollectForAllocation op(gc_count_before, word_size);
495 op.set_allocation_context(AllocationContext::current());
496
497 // ...and get the VM thread to execute it.
498 VMThread::execute(&op);
499
500 if (op.prologue_succeeded() && op.pause_succeeded()) {
501 // If the operation was successful we'll return the result even
502 // if it is NULL. If the allocation attempt failed immediately
503 // after a Full GC, it's unlikely we'll be able to allocate now.
504 HeapWord* result = op.result();
505 if (result != NULL && !is_humongous(word_size)) {
506 // Allocations that take place on VM operations do not do any
507 // card dirtying and we have to do it here. We only have to do
508 // this for non-humongous allocations, though.
509 dirty_young_block(result, word_size);
510 }
511 return result;
512 } else {
513 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
514 return NULL;
515 }
516 assert(op.result() == NULL,
517 "the result should be NULL if the VM op did not succeed");
518 }
519
520 // Give a warning if we seem to be looping forever.
521 if ((QueuedAllocationWarningCount > 0) &&
522 (try_count % QueuedAllocationWarningCount == 0)) {
523 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
524 }
525 }
526
527 ShouldNotReachHere();
528 return NULL;
529 }
530
531 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
532 AllocationContext_t context,
533 uint* gc_count_before_ret,
534 uint* gclocker_retry_count_ret) {
535 // Make sure you read the note in attempt_allocation_humongous().
536
537 assert_heap_not_locked_and_not_at_safepoint();
538 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
539 "be called for humongous allocation requests");
540
541 // We should only get here after the first-level allocation attempt
542 // (attempt_allocation()) failed to allocate.
543
544 // We will loop until a) we manage to successfully perform the
545 // allocation or b) we successfully schedule a collection which
546 // fails to perform the allocation. b) is the only case when we'll
547 // return NULL.
548 HeapWord* result = NULL;
549 for (int try_count = 1; /* we'll return */; try_count += 1) {
550 bool should_try_gc;
551 uint gc_count_before;
552
553 {
554 MutexLockerEx x(Heap_lock);
555 result = _allocator->attempt_allocation_locked(word_size, context);
556 if (result != NULL) {
557 return result;
558 }
559
560 if (GCLocker::is_active_and_needs_gc()) {
561 if (g1_policy()->can_expand_young_list()) {
562 // No need for an ergo verbose message here,
563 // can_expand_young_list() does this when it returns true.
564 result = _allocator->attempt_allocation_force(word_size, context);
565 if (result != NULL) {
566 return result;
567 }
568 }
569 should_try_gc = false;
570 } else {
571 // The GCLocker may not be active but the GCLocker initiated
572 // GC may not yet have been performed (GCLocker::needs_gc()
573 // returns true). In this case we do not try this GC and
574 // wait until the GCLocker initiated GC is performed, and
575 // then retry the allocation.
576 if (GCLocker::needs_gc()) {
577 should_try_gc = false;
578 } else {
579 // Read the GC count while still holding the Heap_lock.
580 gc_count_before = total_collections();
581 should_try_gc = true;
582 }
583 }
584 }
585
586 if (should_try_gc) {
587 bool succeeded;
588 result = do_collection_pause(word_size, gc_count_before, &succeeded,
589 GCCause::_g1_inc_collection_pause);
590 if (result != NULL) {
591 assert(succeeded, "only way to get back a non-NULL result");
592 return result;
593 }
594
595 if (succeeded) {
596 // If we get here we successfully scheduled a collection which
597 // failed to allocate. No point in trying to allocate
598 // further. We'll just return NULL.
599 MutexLockerEx x(Heap_lock);
600 *gc_count_before_ret = total_collections();
601 return NULL;
602 }
603 } else {
604 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
605 MutexLockerEx x(Heap_lock);
606 *gc_count_before_ret = total_collections();
607 return NULL;
608 }
609 // The GCLocker is either active or the GCLocker initiated
610 // GC has not yet been performed. Stall until it is and
611 // then retry the allocation.
612 GCLocker::stall_until_clear();
613 (*gclocker_retry_count_ret) += 1;
614 }
615
616 // We can reach here if we were unsuccessful in scheduling a
617 // collection (because another thread beat us to it) or if we were
618 // stalled due to the GC locker. In either can we should retry the
619 // allocation attempt in case another thread successfully
620 // performed a collection and reclaimed enough space. We do the
621 // first attempt (without holding the Heap_lock) here and the
622 // follow-on attempt will be at the start of the next loop
623 // iteration (after taking the Heap_lock).
624 result = _allocator->attempt_allocation(word_size, context);
625 if (result != NULL) {
626 return result;
627 }
628
629 // Give a warning if we seem to be looping forever.
630 if ((QueuedAllocationWarningCount > 0) &&
631 (try_count % QueuedAllocationWarningCount == 0)) {
632 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
633 "retries %d times", try_count);
634 }
635 }
636
637 ShouldNotReachHere();
638 return NULL;
639 }
640
641 void G1CollectedHeap::begin_archive_alloc_range() {
642 assert_at_safepoint(true /* should_be_vm_thread */);
643 if (_archive_allocator == NULL) {
644 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
645 }
646 }
647
648 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
649 // Allocations in archive regions cannot be of a size that would be considered
650 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
651 // may be different at archive-restore time.
652 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
653 }
654
655 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
656 assert_at_safepoint(true /* should_be_vm_thread */);
657 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
658 if (is_archive_alloc_too_large(word_size)) {
659 return NULL;
660 }
661 return _archive_allocator->archive_mem_allocate(word_size);
662 }
663
664 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
665 size_t end_alignment_in_bytes) {
666 assert_at_safepoint(true /* should_be_vm_thread */);
667 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
668
669 // Call complete_archive to do the real work, filling in the MemRegion
670 // array with the archive regions.
671 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
672 delete _archive_allocator;
673 _archive_allocator = NULL;
674 }
675
676 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
677 assert(ranges != NULL, "MemRegion array NULL");
678 assert(count != 0, "No MemRegions provided");
679 MemRegion reserved = _hrm.reserved();
680 for (size_t i = 0; i < count; i++) {
681 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
682 return false;
683 }
684 }
685 return true;
686 }
687
688 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
689 assert(!is_init_completed(), "Expect to be called at JVM init time");
690 assert(ranges != NULL, "MemRegion array NULL");
691 assert(count != 0, "No MemRegions provided");
692 MutexLockerEx x(Heap_lock);
693
694 MemRegion reserved = _hrm.reserved();
695 HeapWord* prev_last_addr = NULL;
696 HeapRegion* prev_last_region = NULL;
697
698 // Temporarily disable pretouching of heap pages. This interface is used
699 // when mmap'ing archived heap data in, so pre-touching is wasted.
700 FlagSetting fs(AlwaysPreTouch, false);
701
702 // Enable archive object checking used by G1MarkSweep. We have to let it know
703 // about each archive range, so that objects in those ranges aren't marked.
704 G1ArchiveAllocator::enable_archive_object_check();
705
706 // For each specified MemRegion range, allocate the corresponding G1
707 // regions and mark them as archive regions. We expect the ranges in
708 // ascending starting address order, without overlap.
709 for (size_t i = 0; i < count; i++) {
710 MemRegion curr_range = ranges[i];
711 HeapWord* start_address = curr_range.start();
712 size_t word_size = curr_range.word_size();
713 HeapWord* last_address = curr_range.last();
714 size_t commits = 0;
715
716 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
717 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
718 p2i(start_address), p2i(last_address));
719 guarantee(start_address > prev_last_addr,
720 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
721 p2i(start_address), p2i(prev_last_addr));
722 prev_last_addr = last_address;
723
724 // Check for ranges that start in the same G1 region in which the previous
725 // range ended, and adjust the start address so we don't try to allocate
726 // the same region again. If the current range is entirely within that
727 // region, skip it, just adjusting the recorded top.
728 HeapRegion* start_region = _hrm.addr_to_region(start_address);
729 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
730 start_address = start_region->end();
731 if (start_address > last_address) {
732 increase_used(word_size * HeapWordSize);
733 start_region->set_top(last_address + 1);
734 continue;
735 }
736 start_region->set_top(start_address);
737 curr_range = MemRegion(start_address, last_address + 1);
738 start_region = _hrm.addr_to_region(start_address);
739 }
740
741 // Perform the actual region allocation, exiting if it fails.
742 // Then note how much new space we have allocated.
743 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
744 return false;
745 }
746 increase_used(word_size * HeapWordSize);
747 if (commits != 0) {
748 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
749 HeapRegion::GrainWords * HeapWordSize * commits);
750
751 }
752
753 // Mark each G1 region touched by the range as archive, add it to the old set,
754 // and set the allocation context and top.
755 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
756 HeapRegion* last_region = _hrm.addr_to_region(last_address);
757 prev_last_region = last_region;
758
759 while (curr_region != NULL) {
760 assert(curr_region->is_empty() && !curr_region->is_pinned(),
761 "Region already in use (index %u)", curr_region->hrm_index());
762 curr_region->set_allocation_context(AllocationContext::system());
763 curr_region->set_archive();
764 _hr_printer.alloc(curr_region);
765 _old_set.add(curr_region);
766 if (curr_region != last_region) {
767 curr_region->set_top(curr_region->end());
768 curr_region = _hrm.next_region_in_heap(curr_region);
769 } else {
770 curr_region->set_top(last_address + 1);
771 curr_region = NULL;
772 }
773 }
774
775 // Notify mark-sweep of the archive range.
776 G1ArchiveAllocator::set_range_archive(curr_range, true);
777 }
778 return true;
779 }
780
781 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
782 assert(!is_init_completed(), "Expect to be called at JVM init time");
783 assert(ranges != NULL, "MemRegion array NULL");
784 assert(count != 0, "No MemRegions provided");
785 MemRegion reserved = _hrm.reserved();
786 HeapWord *prev_last_addr = NULL;
787 HeapRegion* prev_last_region = NULL;
788
789 // For each MemRegion, create filler objects, if needed, in the G1 regions
790 // that contain the address range. The address range actually within the
791 // MemRegion will not be modified. That is assumed to have been initialized
792 // elsewhere, probably via an mmap of archived heap data.
793 MutexLockerEx x(Heap_lock);
794 for (size_t i = 0; i < count; i++) {
795 HeapWord* start_address = ranges[i].start();
796 HeapWord* last_address = ranges[i].last();
797
798 assert(reserved.contains(start_address) && reserved.contains(last_address),
799 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
800 p2i(start_address), p2i(last_address));
801 assert(start_address > prev_last_addr,
802 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
803 p2i(start_address), p2i(prev_last_addr));
804
805 HeapRegion* start_region = _hrm.addr_to_region(start_address);
806 HeapRegion* last_region = _hrm.addr_to_region(last_address);
807 HeapWord* bottom_address = start_region->bottom();
808
809 // Check for a range beginning in the same region in which the
810 // previous one ended.
811 if (start_region == prev_last_region) {
812 bottom_address = prev_last_addr + 1;
813 }
814
815 // Verify that the regions were all marked as archive regions by
816 // alloc_archive_regions.
817 HeapRegion* curr_region = start_region;
818 while (curr_region != NULL) {
819 guarantee(curr_region->is_archive(),
820 "Expected archive region at index %u", curr_region->hrm_index());
821 if (curr_region != last_region) {
822 curr_region = _hrm.next_region_in_heap(curr_region);
823 } else {
824 curr_region = NULL;
825 }
826 }
827
828 prev_last_addr = last_address;
829 prev_last_region = last_region;
830
831 // Fill the memory below the allocated range with dummy object(s),
832 // if the region bottom does not match the range start, or if the previous
833 // range ended within the same G1 region, and there is a gap.
834 if (start_address != bottom_address) {
835 size_t fill_size = pointer_delta(start_address, bottom_address);
836 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
837 increase_used(fill_size * HeapWordSize);
838 }
839 }
840 }
841
842 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
843 uint* gc_count_before_ret,
844 uint* gclocker_retry_count_ret) {
845 assert_heap_not_locked_and_not_at_safepoint();
846 assert(!is_humongous(word_size), "attempt_allocation() should not "
847 "be called for humongous allocation requests");
848
849 AllocationContext_t context = AllocationContext::current();
850 HeapWord* result = _allocator->attempt_allocation(word_size, context);
851
852 if (result == NULL) {
853 result = attempt_allocation_slow(word_size,
854 context,
855 gc_count_before_ret,
856 gclocker_retry_count_ret);
857 }
858 assert_heap_not_locked();
859 if (result != NULL) {
860 dirty_young_block(result, word_size);
861 }
862 return result;
863 }
864
865 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
866 assert(!is_init_completed(), "Expect to be called at JVM init time");
867 assert(ranges != NULL, "MemRegion array NULL");
868 assert(count != 0, "No MemRegions provided");
869 MemRegion reserved = _hrm.reserved();
870 HeapWord* prev_last_addr = NULL;
871 HeapRegion* prev_last_region = NULL;
872 size_t size_used = 0;
873 size_t uncommitted_regions = 0;
874
875 // For each Memregion, free the G1 regions that constitute it, and
876 // notify mark-sweep that the range is no longer to be considered 'archive.'
877 MutexLockerEx x(Heap_lock);
878 for (size_t i = 0; i < count; i++) {
879 HeapWord* start_address = ranges[i].start();
880 HeapWord* last_address = ranges[i].last();
881
882 assert(reserved.contains(start_address) && reserved.contains(last_address),
883 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
884 p2i(start_address), p2i(last_address));
885 assert(start_address > prev_last_addr,
886 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
887 p2i(start_address), p2i(prev_last_addr));
888 size_used += ranges[i].byte_size();
889 prev_last_addr = last_address;
890
891 HeapRegion* start_region = _hrm.addr_to_region(start_address);
892 HeapRegion* last_region = _hrm.addr_to_region(last_address);
893
894 // Check for ranges that start in the same G1 region in which the previous
895 // range ended, and adjust the start address so we don't try to free
896 // the same region again. If the current range is entirely within that
897 // region, skip it.
898 if (start_region == prev_last_region) {
899 start_address = start_region->end();
900 if (start_address > last_address) {
901 continue;
902 }
903 start_region = _hrm.addr_to_region(start_address);
904 }
905 prev_last_region = last_region;
906
907 // After verifying that each region was marked as an archive region by
908 // alloc_archive_regions, set it free and empty and uncommit it.
909 HeapRegion* curr_region = start_region;
910 while (curr_region != NULL) {
911 guarantee(curr_region->is_archive(),
912 "Expected archive region at index %u", curr_region->hrm_index());
913 uint curr_index = curr_region->hrm_index();
914 _old_set.remove(curr_region);
915 curr_region->set_free();
916 curr_region->set_top(curr_region->bottom());
917 if (curr_region != last_region) {
918 curr_region = _hrm.next_region_in_heap(curr_region);
919 } else {
920 curr_region = NULL;
921 }
922 _hrm.shrink_at(curr_index, 1);
923 uncommitted_regions++;
924 }
925
926 // Notify mark-sweep that this is no longer an archive range.
927 G1ArchiveAllocator::set_range_archive(ranges[i], false);
928 }
929
930 if (uncommitted_regions != 0) {
931 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
932 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
933 }
934 decrease_used(size_used);
935 }
936
937 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
938 uint* gc_count_before_ret,
939 uint* gclocker_retry_count_ret) {
940 // The structure of this method has a lot of similarities to
941 // attempt_allocation_slow(). The reason these two were not merged
942 // into a single one is that such a method would require several "if
943 // allocation is not humongous do this, otherwise do that"
944 // conditional paths which would obscure its flow. In fact, an early
945 // version of this code did use a unified method which was harder to
946 // follow and, as a result, it had subtle bugs that were hard to
947 // track down. So keeping these two methods separate allows each to
948 // be more readable. It will be good to keep these two in sync as
949 // much as possible.
950
951 assert_heap_not_locked_and_not_at_safepoint();
952 assert(is_humongous(word_size), "attempt_allocation_humongous() "
953 "should only be called for humongous allocations");
954
955 // Humongous objects can exhaust the heap quickly, so we should check if we
956 // need to start a marking cycle at each humongous object allocation. We do
957 // the check before we do the actual allocation. The reason for doing it
958 // before the allocation is that we avoid having to keep track of the newly
959 // allocated memory while we do a GC.
960 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
961 word_size)) {
962 collect(GCCause::_g1_humongous_allocation);
963 }
964
965 // We will loop until a) we manage to successfully perform the
966 // allocation or b) we successfully schedule a collection which
967 // fails to perform the allocation. b) is the only case when we'll
968 // return NULL.
969 HeapWord* result = NULL;
970 for (int try_count = 1; /* we'll return */; try_count += 1) {
971 bool should_try_gc;
972 uint gc_count_before;
973
974 {
975 MutexLockerEx x(Heap_lock);
976
977 // Given that humongous objects are not allocated in young
978 // regions, we'll first try to do the allocation without doing a
979 // collection hoping that there's enough space in the heap.
980 result = humongous_obj_allocate(word_size, AllocationContext::current());
981 if (result != NULL) {
982 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
983 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
984 return result;
985 }
986
987 if (GCLocker::is_active_and_needs_gc()) {
988 should_try_gc = false;
989 } else {
990 // The GCLocker may not be active but the GCLocker initiated
991 // GC may not yet have been performed (GCLocker::needs_gc()
992 // returns true). In this case we do not try this GC and
993 // wait until the GCLocker initiated GC is performed, and
994 // then retry the allocation.
995 if (GCLocker::needs_gc()) {
996 should_try_gc = false;
997 } else {
998 // Read the GC count while still holding the Heap_lock.
999 gc_count_before = total_collections();
1000 should_try_gc = true;
1001 }
1002 }
1003 }
1004
1005 if (should_try_gc) {
1006 // If we failed to allocate the humongous object, we should try to
1007 // do a collection pause (if we're allowed) in case it reclaims
1008 // enough space for the allocation to succeed after the pause.
1009
1010 bool succeeded;
1011 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1012 GCCause::_g1_humongous_allocation);
1013 if (result != NULL) {
1014 assert(succeeded, "only way to get back a non-NULL result");
1015 return result;
1016 }
1017
1018 if (succeeded) {
1019 // If we get here we successfully scheduled a collection which
1020 // failed to allocate. No point in trying to allocate
1021 // further. We'll just return NULL.
1022 MutexLockerEx x(Heap_lock);
1023 *gc_count_before_ret = total_collections();
1024 return NULL;
1025 }
1026 } else {
1027 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1028 MutexLockerEx x(Heap_lock);
1029 *gc_count_before_ret = total_collections();
1030 return NULL;
1031 }
1032 // The GCLocker is either active or the GCLocker initiated
1033 // GC has not yet been performed. Stall until it is and
1034 // then retry the allocation.
1035 GCLocker::stall_until_clear();
1036 (*gclocker_retry_count_ret) += 1;
1037 }
1038
1039 // We can reach here if we were unsuccessful in scheduling a
1040 // collection (because another thread beat us to it) or if we were
1041 // stalled due to the GC locker. In either can we should retry the
1042 // allocation attempt in case another thread successfully
1043 // performed a collection and reclaimed enough space. Give a
1044 // warning if we seem to be looping forever.
1045
1046 if ((QueuedAllocationWarningCount > 0) &&
1047 (try_count % QueuedAllocationWarningCount == 0)) {
1048 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1049 "retries %d times", try_count);
1050 }
1051 }
1052
1053 ShouldNotReachHere();
1054 return NULL;
1055 }
1056
1057 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1058 AllocationContext_t context,
1059 bool expect_null_mutator_alloc_region) {
1060 assert_at_safepoint(true /* should_be_vm_thread */);
1061 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1062 "the current alloc region was unexpectedly found to be non-NULL");
1063
1064 if (!is_humongous(word_size)) {
1065 return _allocator->attempt_allocation_locked(word_size, context);
1066 } else {
1067 HeapWord* result = humongous_obj_allocate(word_size, context);
1068 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1069 collector_state()->set_initiate_conc_mark_if_possible(true);
1070 }
1071 return result;
1072 }
1073
1074 ShouldNotReachHere();
1075 }
1076
1077 class PostMCRemSetClearClosure: public HeapRegionClosure {
1078 G1CollectedHeap* _g1h;
1079 ModRefBarrierSet* _mr_bs;
1080 public:
1081 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1082 _g1h(g1h), _mr_bs(mr_bs) {}
1083
1084 bool doHeapRegion(HeapRegion* r) {
1085 HeapRegionRemSet* hrrs = r->rem_set();
1086
1087 _g1h->reset_gc_time_stamps(r);
1088
1089 if (r->is_continues_humongous()) {
1090 // We'll assert that the strong code root list and RSet is empty
1091 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1092 assert(hrrs->occupied() == 0, "RSet should be empty");
1093 } else {
1094 hrrs->clear();
1095 }
1096 // You might think here that we could clear just the cards
1097 // corresponding to the used region. But no: if we leave a dirty card
1098 // in a region we might allocate into, then it would prevent that card
1099 // from being enqueued, and cause it to be missed.
1100 // Re: the performance cost: we shouldn't be doing full GC anyway!
1101 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1102
1103 return false;
1104 }
1105 };
1106
1107 void G1CollectedHeap::clear_rsets_post_compaction() {
1108 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1109 heap_region_iterate(&rs_clear);
1110 }
1111
1112 class ParRebuildRSTask: public G1ParallelizeByRegionsTask {
1113 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1114 UpdateRSOopClosure _cl;
1115 public:
1116 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1117 _cl(g1->g1_rem_set(), worker_i) {}
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 public:
1129 ParRebuildRSTask(G1CollectedHeap* g1) :
1130 G1ParallelizeByRegionsTask("ParRebuildRSTask", g1->workers()->active_workers()) {}
1131
1132 void work(uint worker_id) {
1133 G1CollectedHeap* g1 = G1CollectedHeap::heap();
1134 RebuildRSOutOfRegionClosure rebuild_rs(g1, worker_id);
1135 all_heap_regions_work(&rebuild_rs, worker_id);
1136 }
1137 };
1138
1139 class PostCompactionPrinterClosure: public HeapRegionClosure {
1140 private:
1141 G1HRPrinter* _hr_printer;
1142 public:
1143 bool doHeapRegion(HeapRegion* hr) {
1144 assert(!hr->is_young(), "not expecting to find young regions");
1145 _hr_printer->post_compaction(hr);
1146 return false;
1147 }
1148
1149 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1150 : _hr_printer(hr_printer) { }
1151 };
1152
1153 void G1CollectedHeap::print_hrm_post_compaction() {
1154 if (_hr_printer.is_active()) {
1155 PostCompactionPrinterClosure cl(hr_printer());
1156 heap_region_iterate(&cl);
1157 }
1158
1159 }
1160
1161 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1162 bool clear_all_soft_refs) {
1163 assert_at_safepoint(true /* should_be_vm_thread */);
1164
1165 if (GCLocker::check_active_before_gc()) {
1166 return false;
1167 }
1168
1169 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1170 gc_timer->register_gc_start();
1171
1172 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1173 GCIdMark gc_id_mark;
1174 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1175
1176 SvcGCMarker sgcm(SvcGCMarker::FULL);
1177 ResourceMark rm;
1178
1179 print_heap_before_gc();
1180 print_heap_regions();
1181 trace_heap_before_gc(gc_tracer);
1182
1183 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1184
1185 _verifier->verify_region_sets_optional();
1186
1187 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1188 collector_policy()->should_clear_all_soft_refs();
1189
1190 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1191
1192 {
1193 IsGCActiveMark x;
1194
1195 // Timing
1196 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1197 GCTraceCPUTime tcpu;
1198
1199 {
1200 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1201 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1202 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1203
1204 G1HeapTransition heap_transition(this);
1205 g1_policy()->record_full_collection_start();
1206
1207 // Note: When we have a more flexible GC logging framework that
1208 // allows us to add optional attributes to a GC log record we
1209 // could consider timing and reporting how long we wait in the
1210 // following two methods.
1211 wait_while_free_regions_coming();
1212 // If we start the compaction before the CM threads finish
1213 // scanning the root regions we might trip them over as we'll
1214 // be moving objects / updating references. So let's wait until
1215 // they are done. By telling them to abort, they should complete
1216 // early.
1217 _cm->root_regions()->abort();
1218 _cm->root_regions()->wait_until_scan_finished();
1219 append_secondary_free_list_if_not_empty_with_lock();
1220
1221 gc_prologue(true);
1222 increment_total_collections(true /* full gc */);
1223 increment_old_marking_cycles_started();
1224
1225 assert(used() == recalculate_used(), "Should be equal");
1226
1227 _verifier->verify_before_gc();
1228
1229 _verifier->check_bitmaps("Full GC Start");
1230 pre_full_gc_dump(gc_timer);
1231
1232 #if defined(COMPILER2) || INCLUDE_JVMCI
1233 DerivedPointerTable::clear();
1234 #endif
1235
1236 // Disable discovery and empty the discovered lists
1237 // for the CM ref processor.
1238 ref_processor_cm()->disable_discovery();
1239 ref_processor_cm()->abandon_partial_discovery();
1240 ref_processor_cm()->verify_no_references_recorded();
1241
1242 // Abandon current iterations of concurrent marking and concurrent
1243 // refinement, if any are in progress.
1244 concurrent_mark()->abort();
1245
1246 // Make sure we'll choose a new allocation region afterwards.
1247 _allocator->release_mutator_alloc_region();
1248 _allocator->abandon_gc_alloc_regions();
1249 g1_rem_set()->cleanupHRRS();
1250
1251 // We may have added regions to the current incremental collection
1252 // set between the last GC or pause and now. We need to clear the
1253 // incremental collection set and then start rebuilding it afresh
1254 // after this full GC.
1255 abandon_collection_set(collection_set());
1256
1257 tear_down_region_sets(false /* free_list_only */);
1258 collector_state()->set_gcs_are_young(true);
1259
1260 // See the comments in g1CollectedHeap.hpp and
1261 // G1CollectedHeap::ref_processing_init() about
1262 // how reference processing currently works in G1.
1263
1264 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1265 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1266
1267 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1268 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1269
1270 ref_processor_stw()->enable_discovery();
1271 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1272
1273 // Do collection work
1274 {
1275 HandleMark hm; // Discard invalid handles created during gc
1276 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1277 }
1278
1279 assert(num_free_regions() == 0, "we should not have added any free regions");
1280 rebuild_region_sets(false /* free_list_only */);
1281
1282 // Enqueue any discovered reference objects that have
1283 // not been removed from the discovered lists.
1284 ref_processor_stw()->enqueue_discovered_references();
1285
1286 #if defined(COMPILER2) || INCLUDE_JVMCI
1287 DerivedPointerTable::update_pointers();
1288 #endif
1289
1290 MemoryService::track_memory_usage();
1291
1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293 ref_processor_stw()->verify_no_references_recorded();
1294
1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296 ClassLoaderDataGraph::purge();
1297 MetaspaceAux::verify_metrics();
1298
1299 // Note: since we've just done a full GC, concurrent
1300 // marking is no longer active. Therefore we need not
1301 // re-enable reference discovery for the CM ref processor.
1302 // That will be done at the start of the next marking cycle.
1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304 ref_processor_cm()->verify_no_references_recorded();
1305
1306 reset_gc_time_stamp();
1307 // Since everything potentially moved, we will clear all remembered
1308 // sets, and clear all cards. Later we will rebuild remembered
1309 // sets. We will also reset the GC time stamps of the regions.
1310 clear_rsets_post_compaction();
1311 check_gc_time_stamps();
1312
1313 resize_if_necessary_after_full_collection();
1314
1315 // We should do this after we potentially resize the heap so
1316 // that all the COMMIT / UNCOMMIT events are generated before
1317 // the compaction events.
1318 print_hrm_post_compaction();
1319
1320 if (_hot_card_cache->use_cache()) {
1321 _hot_card_cache->reset_card_counts();
1322 _hot_card_cache->reset_hot_cache();
1323 }
1324
1325 // Rebuild remembered sets of all regions.
1326 uint n_workers =
1327 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1328 workers()->active_workers(),
1329 Threads::number_of_non_daemon_threads());
1330 workers()->update_active_workers(n_workers);
1331 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1332
1333 ParRebuildRSTask rebuild_rs_task(this);
1334 workers()->run_task(&rebuild_rs_task);
1335
1336 // Rebuild the strong code root lists for each region
1337 rebuild_strong_code_roots();
1338
1339 if (true) { // FIXME
1340 MetaspaceGC::compute_new_size();
1341 }
1342
1343 #ifdef TRACESPINNING
1344 ParallelTaskTerminator::print_termination_counts();
1345 #endif
1346
1347 // Discard all rset updates
1348 JavaThread::dirty_card_queue_set().abandon_logs();
1349 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1350
1351 // At this point there should be no regions in the
1352 // entire heap tagged as young.
1353 assert(check_young_list_empty(), "young list should be empty at this point");
1354
1355 // Update the number of full collections that have been completed.
1356 increment_old_marking_cycles_completed(false /* concurrent */);
1357
1358 _hrm.verify_optional();
1359 _verifier->verify_region_sets_optional();
1360
1361 _verifier->verify_after_gc();
1362
1363 // Clear the previous marking bitmap, if needed for bitmap verification.
1364 // Note we cannot do this when we clear the next marking bitmap in
1365 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1366 // objects marked during a full GC against the previous bitmap.
1367 // But we need to clear it before calling check_bitmaps below since
1368 // the full GC has compacted objects and updated TAMS but not updated
1369 // the prev bitmap.
1370 if (G1VerifyBitmaps) {
1371 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1372 _cm->clear_prev_bitmap(workers());
1373 }
1374 _verifier->check_bitmaps("Full GC End");
1375
1376 double start = os::elapsedTime();
1377 start_new_collection_set();
1378 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
1379
1380 _allocator->init_mutator_alloc_region();
1381
1382 g1_policy()->record_full_collection_end();
1383
1384 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1385 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1386 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1387 // before any GC notifications are raised.
1388 g1mm()->update_sizes();
1389
1390 gc_epilogue(true);
1391
1392 heap_transition.print();
1393
1394 print_heap_after_gc();
1395 print_heap_regions();
1396 trace_heap_after_gc(gc_tracer);
1397
1398 post_full_gc_dump(gc_timer);
1399 }
1400
1401 gc_timer->register_gc_end();
1402 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1403 }
1404
1405 return true;
1406 }
1407
1408 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1409 // Currently, there is no facility in the do_full_collection(bool) API to notify
1410 // the caller that the collection did not succeed (e.g., because it was locked
1411 // out by the GC locker). So, right now, we'll ignore the return value.
1412 bool dummy = do_full_collection(true, /* explicit_gc */
1413 clear_all_soft_refs);
1414 }
1415
1416 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1417 // Include bytes that will be pre-allocated to support collections, as "used".
1418 const size_t used_after_gc = used();
1419 const size_t capacity_after_gc = capacity();
1420 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1421
1422 // This is enforced in arguments.cpp.
1423 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1424 "otherwise the code below doesn't make sense");
1425
1426 // We don't have floating point command-line arguments
1427 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1428 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1429 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1430 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1431
1432 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1433 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1434
1435 // We have to be careful here as these two calculations can overflow
1436 // 32-bit size_t's.
1437 double used_after_gc_d = (double) used_after_gc;
1438 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1439 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1440
1441 // Let's make sure that they are both under the max heap size, which
1442 // by default will make them fit into a size_t.
1443 double desired_capacity_upper_bound = (double) max_heap_size;
1444 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1445 desired_capacity_upper_bound);
1446 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1447 desired_capacity_upper_bound);
1448
1449 // We can now safely turn them into size_t's.
1450 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1451 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1452
1453 // This assert only makes sense here, before we adjust them
1454 // with respect to the min and max heap size.
1455 assert(minimum_desired_capacity <= maximum_desired_capacity,
1456 "minimum_desired_capacity = " SIZE_FORMAT ", "
1457 "maximum_desired_capacity = " SIZE_FORMAT,
1458 minimum_desired_capacity, maximum_desired_capacity);
1459
1460 // Should not be greater than the heap max size. No need to adjust
1461 // it with respect to the heap min size as it's a lower bound (i.e.,
1462 // we'll try to make the capacity larger than it, not smaller).
1463 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1464 // Should not be less than the heap min size. No need to adjust it
1465 // with respect to the heap max size as it's an upper bound (i.e.,
1466 // we'll try to make the capacity smaller than it, not greater).
1467 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1468
1469 if (capacity_after_gc < minimum_desired_capacity) {
1470 // Don't expand unless it's significant
1471 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1472
1473 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1474 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1475 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1476
1477 expand(expand_bytes, _workers);
1478
1479 // No expansion, now see if we want to shrink
1480 } else if (capacity_after_gc > maximum_desired_capacity) {
1481 // Capacity too large, compute shrinking size
1482 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1483
1484 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1485 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1486 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1487
1488 shrink(shrink_bytes);
1489 }
1490 }
1491
1492 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1493 AllocationContext_t context,
1494 bool do_gc,
1495 bool clear_all_soft_refs,
1496 bool expect_null_mutator_alloc_region,
1497 bool* gc_succeeded) {
1498 *gc_succeeded = true;
1499 // Let's attempt the allocation first.
1500 HeapWord* result =
1501 attempt_allocation_at_safepoint(word_size,
1502 context,
1503 expect_null_mutator_alloc_region);
1504 if (result != NULL) {
1505 assert(*gc_succeeded, "sanity");
1506 return result;
1507 }
1508
1509 // In a G1 heap, we're supposed to keep allocation from failing by
1510 // incremental pauses. Therefore, at least for now, we'll favor
1511 // expansion over collection. (This might change in the future if we can
1512 // do something smarter than full collection to satisfy a failed alloc.)
1513 result = expand_and_allocate(word_size, context);
1514 if (result != NULL) {
1515 assert(*gc_succeeded, "sanity");
1516 return result;
1517 }
1518
1519 if (do_gc) {
1520 // Expansion didn't work, we'll try to do a Full GC.
1521 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1522 clear_all_soft_refs);
1523 }
1524
1525 return NULL;
1526 }
1527
1528 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1529 AllocationContext_t context,
1530 bool* succeeded) {
1531 assert_at_safepoint(true /* should_be_vm_thread */);
1532
1533 // Attempts to allocate followed by Full GC.
1534 HeapWord* result =
1535 satisfy_failed_allocation_helper(word_size,
1536 context,
1537 true, /* do_gc */
1538 false, /* clear_all_soft_refs */
1539 false, /* expect_null_mutator_alloc_region */
1540 succeeded);
1541
1542 if (result != NULL || !*succeeded) {
1543 return result;
1544 }
1545
1546 // Attempts to allocate followed by Full GC that will collect all soft references.
1547 result = satisfy_failed_allocation_helper(word_size,
1548 context,
1549 true, /* do_gc */
1550 true, /* clear_all_soft_refs */
1551 true, /* expect_null_mutator_alloc_region */
1552 succeeded);
1553
1554 if (result != NULL || !*succeeded) {
1555 return result;
1556 }
1557
1558 // Attempts to allocate, no GC
1559 result = satisfy_failed_allocation_helper(word_size,
1560 context,
1561 false, /* do_gc */
1562 false, /* clear_all_soft_refs */
1563 true, /* expect_null_mutator_alloc_region */
1564 succeeded);
1565
1566 if (result != NULL) {
1567 assert(*succeeded, "sanity");
1568 return result;
1569 }
1570
1571 assert(!collector_policy()->should_clear_all_soft_refs(),
1572 "Flag should have been handled and cleared prior to this point");
1573
1574 // What else? We might try synchronous finalization later. If the total
1575 // space available is large enough for the allocation, then a more
1576 // complete compaction phase than we've tried so far might be
1577 // appropriate.
1578 assert(*succeeded, "sanity");
1579 return NULL;
1580 }
1581
1582 // Attempting to expand the heap sufficiently
1583 // to support an allocation of the given "word_size". If
1584 // successful, perform the allocation and return the address of the
1585 // allocated block, or else "NULL".
1586
1587 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1588 assert_at_safepoint(true /* should_be_vm_thread */);
1589
1590 _verifier->verify_region_sets_optional();
1591
1592 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1593 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1594 word_size * HeapWordSize);
1595
1596
1597 if (expand(expand_bytes, _workers)) {
1598 _hrm.verify_optional();
1599 _verifier->verify_region_sets_optional();
1600 return attempt_allocation_at_safepoint(word_size,
1601 context,
1602 false /* expect_null_mutator_alloc_region */);
1603 }
1604 return NULL;
1605 }
1606
1607 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1608 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1609 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1610 HeapRegion::GrainBytes);
1611
1612 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1613 expand_bytes, aligned_expand_bytes);
1614
1615 if (is_maximal_no_gc()) {
1616 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1617 return false;
1618 }
1619
1620 double expand_heap_start_time_sec = os::elapsedTime();
1621 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1622 assert(regions_to_expand > 0, "Must expand by at least one region");
1623
1624 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1625 if (expand_time_ms != NULL) {
1626 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1627 }
1628
1629 if (expanded_by > 0) {
1630 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1631 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1632 g1_policy()->record_new_heap_size(num_regions());
1633 } else {
1634 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1635
1636 // The expansion of the virtual storage space was unsuccessful.
1637 // Let's see if it was because we ran out of swap.
1638 if (G1ExitOnExpansionFailure &&
1639 _hrm.available() >= regions_to_expand) {
1640 // We had head room...
1641 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1642 }
1643 }
1644 return regions_to_expand > 0;
1645 }
1646
1647 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1648 size_t aligned_shrink_bytes =
1649 ReservedSpace::page_align_size_down(shrink_bytes);
1650 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1651 HeapRegion::GrainBytes);
1652 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1653
1654 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1655 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1656
1657
1658 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",
1659 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1660 if (num_regions_removed > 0) {
1661 g1_policy()->record_new_heap_size(num_regions());
1662 } else {
1663 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1664 }
1665 }
1666
1667 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1668 _verifier->verify_region_sets_optional();
1669
1670 // We should only reach here at the end of a Full GC which means we
1671 // should not not be holding to any GC alloc regions. The method
1672 // below will make sure of that and do any remaining clean up.
1673 _allocator->abandon_gc_alloc_regions();
1674
1675 // Instead of tearing down / rebuilding the free lists here, we
1676 // could instead use the remove_all_pending() method on free_list to
1677 // remove only the ones that we need to remove.
1678 tear_down_region_sets(true /* free_list_only */);
1679 shrink_helper(shrink_bytes);
1680 rebuild_region_sets(true /* free_list_only */);
1681
1682 _hrm.verify_optional();
1683 _verifier->verify_region_sets_optional();
1684 }
1685
1686 // Public methods.
1687
1688 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1689 CollectedHeap(),
1690 _collector_policy(collector_policy),
1691 _g1_policy(create_g1_policy()),
1692 _collection_set(this, _g1_policy),
1693 _dirty_card_queue_set(false),
1694 _is_alive_closure_cm(this),
1695 _is_alive_closure_stw(this),
1696 _ref_processor_cm(NULL),
1697 _ref_processor_stw(NULL),
1698 _bot(NULL),
1699 _hot_card_cache(NULL),
1700 _g1_rem_set(NULL),
1701 _cg1r(NULL),
1702 _g1mm(NULL),
1703 _refine_cte_cl(NULL),
1704 _preserved_marks_set(true /* in_c_heap */),
1705 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1706 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1707 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1708 _humongous_reclaim_candidates(),
1709 _has_humongous_reclaim_candidates(false),
1710 _archive_allocator(NULL),
1711 _free_regions_coming(false),
1712 _gc_time_stamp(0),
1713 _summary_bytes_used(0),
1714 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1715 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1716 _expand_heap_after_alloc_failure(true),
1717 _old_marking_cycles_started(0),
1718 _old_marking_cycles_completed(0),
1719 _in_cset_fast_test(),
1720 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1721 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1722
1723 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1724 /* are_GC_task_threads */true,
1725 /* are_ConcurrentGC_threads */false);
1726 _workers->initialize_workers();
1727 _verifier = new G1HeapVerifier(this);
1728
1729 _allocator = G1Allocator::create_allocator(this);
1730
1731 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1732
1733 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1734
1735 // Override the default _filler_array_max_size so that no humongous filler
1736 // objects are created.
1737 _filler_array_max_size = _humongous_object_threshold_in_words;
1738
1739 uint n_queues = ParallelGCThreads;
1740 _task_queues = new RefToScanQueueSet(n_queues);
1741
1742 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1743
1744 for (uint i = 0; i < n_queues; i++) {
1745 RefToScanQueue* q = new RefToScanQueue();
1746 q->initialize();
1747 _task_queues->register_queue(i, q);
1748 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1749 }
1750
1751 // Initialize the G1EvacuationFailureALot counters and flags.
1752 NOT_PRODUCT(reset_evacuation_should_fail();)
1753
1754 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1755 }
1756
1757 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1758 size_t size,
1759 size_t translation_factor) {
1760 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1761 // Allocate a new reserved space, preferring to use large pages.
1762 ReservedSpace rs(size, preferred_page_size);
1763 G1RegionToSpaceMapper* result =
1764 G1RegionToSpaceMapper::create_mapper(rs,
1765 size,
1766 rs.alignment(),
1767 HeapRegion::GrainBytes,
1768 translation_factor,
1769 mtGC);
1770
1771 os::trace_page_sizes_for_requested_size(description,
1772 size,
1773 preferred_page_size,
1774 rs.alignment(),
1775 rs.base(),
1776 rs.size());
1777
1778 return result;
1779 }
1780
1781 jint G1CollectedHeap::initialize() {
1782 CollectedHeap::pre_initialize();
1783 os::enable_vtime();
1784
1785 // Necessary to satisfy locking discipline assertions.
1786
1787 MutexLocker x(Heap_lock);
1788
1789 // While there are no constraints in the GC code that HeapWordSize
1790 // be any particular value, there are multiple other areas in the
1791 // system which believe this to be true (e.g. oop->object_size in some
1792 // cases incorrectly returns the size in wordSize units rather than
1793 // HeapWordSize).
1794 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1795
1796 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1797 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1798 size_t heap_alignment = collector_policy()->heap_alignment();
1799
1800 // Ensure that the sizes are properly aligned.
1801 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1802 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1803 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1804
1805 _refine_cte_cl = new RefineCardTableEntryClosure();
1806
1807 jint ecode = JNI_OK;
1808 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1809 if (_cg1r == NULL) {
1810 return ecode;
1811 }
1812
1813 // Reserve the maximum.
1814
1815 // When compressed oops are enabled, the preferred heap base
1816 // is calculated by subtracting the requested size from the
1817 // 32Gb boundary and using the result as the base address for
1818 // heap reservation. If the requested size is not aligned to
1819 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1820 // into the ReservedHeapSpace constructor) then the actual
1821 // base of the reserved heap may end up differing from the
1822 // address that was requested (i.e. the preferred heap base).
1823 // If this happens then we could end up using a non-optimal
1824 // compressed oops mode.
1825
1826 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1827 heap_alignment);
1828
1829 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1830
1831 // Create the barrier set for the entire reserved region.
1832 G1SATBCardTableLoggingModRefBS* bs
1833 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1834 bs->initialize();
1835 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1836 set_barrier_set(bs);
1837
1838 // Create the hot card cache.
1839 _hot_card_cache = new G1HotCardCache(this);
1840
1841 // Also create a G1 rem set.
1842 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1843
1844 // Carve out the G1 part of the heap.
1845 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1846 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1847 G1RegionToSpaceMapper* heap_storage =
1848 G1RegionToSpaceMapper::create_mapper(g1_rs,
1849 g1_rs.size(),
1850 page_size,
1851 HeapRegion::GrainBytes,
1852 1,
1853 mtJavaHeap);
1854 os::trace_page_sizes("Heap",
1855 collector_policy()->min_heap_byte_size(),
1856 max_byte_size,
1857 page_size,
1858 heap_rs.base(),
1859 heap_rs.size());
1860 heap_storage->set_mapping_changed_listener(&_listener);
1861
1862 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1863 G1RegionToSpaceMapper* bot_storage =
1864 create_aux_memory_mapper("Block Offset Table",
1865 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1866 G1BlockOffsetTable::heap_map_factor());
1867
1868 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1869 G1RegionToSpaceMapper* cardtable_storage =
1870 create_aux_memory_mapper("Card Table",
1871 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1872 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1873
1874 G1RegionToSpaceMapper* card_counts_storage =
1875 create_aux_memory_mapper("Card Counts Table",
1876 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1877 G1CardCounts::heap_map_factor());
1878
1879 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1880 G1RegionToSpaceMapper* prev_bitmap_storage =
1881 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1882 G1RegionToSpaceMapper* next_bitmap_storage =
1883 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1884
1885 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1886 g1_barrier_set()->initialize(cardtable_storage);
1887 // Do later initialization work for concurrent refinement.
1888 _hot_card_cache->initialize(card_counts_storage);
1889
1890 // 6843694 - ensure that the maximum region index can fit
1891 // in the remembered set structures.
1892 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1893 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1894
1895 g1_rem_set()->initialize(max_capacity(), max_regions());
1896
1897 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1898 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1899 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1900 "too many cards per region");
1901
1902 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1903
1904 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1905
1906 {
1907 HeapWord* start = _hrm.reserved().start();
1908 HeapWord* end = _hrm.reserved().end();
1909 size_t granularity = HeapRegion::GrainBytes;
1910
1911 _in_cset_fast_test.initialize(start, end, granularity);
1912 _humongous_reclaim_candidates.initialize(start, end, granularity);
1913 }
1914
1915 // Create the G1ConcurrentMark data structure and thread.
1916 // (Must do this late, so that "max_regions" is defined.)
1917 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1918 if (_cm == NULL || !_cm->completed_initialization()) {
1919 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1920 return JNI_ENOMEM;
1921 }
1922 _cmThread = _cm->cmThread();
1923
1924 // Now expand into the initial heap size.
1925 if (!expand(init_byte_size, _workers)) {
1926 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1927 return JNI_ENOMEM;
1928 }
1929
1930 // Perform any initialization actions delegated to the policy.
1931 g1_policy()->init(this, &_collection_set);
1932
1933 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1934 SATB_Q_FL_lock,
1935 G1SATBProcessCompletedThreshold,
1936 Shared_SATB_Q_lock);
1937
1938 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1939 DirtyCardQ_CBL_mon,
1940 DirtyCardQ_FL_lock,
1941 (int)concurrent_g1_refine()->yellow_zone(),
1942 (int)concurrent_g1_refine()->red_zone(),
1943 Shared_DirtyCardQ_lock,
1944 NULL, // fl_owner
1945 true); // init_free_ids
1946
1947 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1948 DirtyCardQ_CBL_mon,
1949 DirtyCardQ_FL_lock,
1950 -1, // never trigger processing
1951 -1, // no limit on length
1952 Shared_DirtyCardQ_lock,
1953 &JavaThread::dirty_card_queue_set());
1954
1955 // Here we allocate the dummy HeapRegion that is required by the
1956 // G1AllocRegion class.
1957 HeapRegion* dummy_region = _hrm.get_dummy_region();
1958
1959 // We'll re-use the same region whether the alloc region will
1960 // require BOT updates or not and, if it doesn't, then a non-young
1961 // region will complain that it cannot support allocations without
1962 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1963 dummy_region->set_eden();
1964 // Make sure it's full.
1965 dummy_region->set_top(dummy_region->end());
1966 G1AllocRegion::setup(this, dummy_region);
1967
1968 _allocator->init_mutator_alloc_region();
1969
1970 // Do create of the monitoring and management support so that
1971 // values in the heap have been properly initialized.
1972 _g1mm = new G1MonitoringSupport(this);
1973
1974 G1StringDedup::initialize();
1975
1976 _preserved_marks_set.init(ParallelGCThreads);
1977
1978 _collection_set.initialize(max_regions());
1979
1980 return JNI_OK;
1981 }
1982
1983 void G1CollectedHeap::stop() {
1984 // Stop all concurrent threads. We do this to make sure these threads
1985 // do not continue to execute and access resources (e.g. logging)
1986 // that are destroyed during shutdown.
1987 _cg1r->stop();
1988 _cmThread->stop();
1989 if (G1StringDedup::is_enabled()) {
1990 G1StringDedup::stop();
1991 }
1992 }
1993
1994 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1995 return HeapRegion::max_region_size();
1996 }
1997
1998 void G1CollectedHeap::post_initialize() {
1999 ref_processing_init();
2000 }
2001
2002 void G1CollectedHeap::ref_processing_init() {
2003 // Reference processing in G1 currently works as follows:
2004 //
2005 // * There are two reference processor instances. One is
2006 // used to record and process discovered references
2007 // during concurrent marking; the other is used to
2008 // record and process references during STW pauses
2009 // (both full and incremental).
2010 // * Both ref processors need to 'span' the entire heap as
2011 // the regions in the collection set may be dotted around.
2012 //
2013 // * For the concurrent marking ref processor:
2014 // * Reference discovery is enabled at initial marking.
2015 // * Reference discovery is disabled and the discovered
2016 // references processed etc during remarking.
2017 // * Reference discovery is MT (see below).
2018 // * Reference discovery requires a barrier (see below).
2019 // * Reference processing may or may not be MT
2020 // (depending on the value of ParallelRefProcEnabled
2021 // and ParallelGCThreads).
2022 // * A full GC disables reference discovery by the CM
2023 // ref processor and abandons any entries on it's
2024 // discovered lists.
2025 //
2026 // * For the STW processor:
2027 // * Non MT discovery is enabled at the start of a full GC.
2028 // * Processing and enqueueing during a full GC is non-MT.
2029 // * During a full GC, references are processed after marking.
2030 //
2031 // * Discovery (may or may not be MT) is enabled at the start
2032 // of an incremental evacuation pause.
2033 // * References are processed near the end of a STW evacuation pause.
2034 // * For both types of GC:
2035 // * Discovery is atomic - i.e. not concurrent.
2036 // * Reference discovery will not need a barrier.
2037
2038 MemRegion mr = reserved_region();
2039
2040 // Concurrent Mark ref processor
2041 _ref_processor_cm =
2042 new ReferenceProcessor(mr, // span
2043 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2044 // mt processing
2045 ParallelGCThreads,
2046 // degree of mt processing
2047 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2048 // mt discovery
2049 MAX2(ParallelGCThreads, ConcGCThreads),
2050 // degree of mt discovery
2051 false,
2052 // Reference discovery is not atomic
2053 &_is_alive_closure_cm);
2054 // is alive closure
2055 // (for efficiency/performance)
2056
2057 // STW ref processor
2058 _ref_processor_stw =
2059 new ReferenceProcessor(mr, // span
2060 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2061 // mt processing
2062 ParallelGCThreads,
2063 // degree of mt processing
2064 (ParallelGCThreads > 1),
2065 // mt discovery
2066 ParallelGCThreads,
2067 // degree of mt discovery
2068 true,
2069 // Reference discovery is atomic
2070 &_is_alive_closure_stw);
2071 // is alive closure
2072 // (for efficiency/performance)
2073 }
2074
2075 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2076 return _collector_policy;
2077 }
2078
2079 size_t G1CollectedHeap::capacity() const {
2080 return _hrm.length() * HeapRegion::GrainBytes;
2081 }
2082
2083 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2084 hr->reset_gc_time_stamp();
2085 }
2086
2087 #ifndef PRODUCT
2088
2089 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2090 private:
2091 unsigned _gc_time_stamp;
2092 bool _failures;
2093
2094 public:
2095 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2096 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2097
2098 virtual bool doHeapRegion(HeapRegion* hr) {
2099 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2100 if (_gc_time_stamp != region_gc_time_stamp) {
2101 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2102 region_gc_time_stamp, _gc_time_stamp);
2103 _failures = true;
2104 }
2105 return false;
2106 }
2107
2108 bool failures() { return _failures; }
2109 };
2110
2111 void G1CollectedHeap::check_gc_time_stamps() {
2112 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2113 heap_region_iterate(&cl);
2114 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2115 }
2116 #endif // PRODUCT
2117
2118 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2119 _hot_card_cache->drain(cl, worker_i);
2120 }
2121
2122 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2123 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2124 size_t n_completed_buffers = 0;
2125 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2126 n_completed_buffers++;
2127 }
2128 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2129 dcqs.clear_n_completed_buffers();
2130 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2131 }
2132
2133 // Computes the sum of the storage used by the various regions.
2134 size_t G1CollectedHeap::used() const {
2135 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2136 if (_archive_allocator != NULL) {
2137 result += _archive_allocator->used();
2138 }
2139 return result;
2140 }
2141
2142 size_t G1CollectedHeap::used_unlocked() const {
2143 return _summary_bytes_used;
2144 }
2145
2146 class SumUsedClosure: public HeapRegionClosure {
2147 size_t _used;
2148 public:
2149 SumUsedClosure() : _used(0) {}
2150 bool doHeapRegion(HeapRegion* r) {
2151 _used += r->used();
2152 return false;
2153 }
2154 size_t result() { return _used; }
2155 };
2156
2157 size_t G1CollectedHeap::recalculate_used() const {
2158 double recalculate_used_start = os::elapsedTime();
2159
2160 SumUsedClosure blk;
2161 heap_region_iterate(&blk);
2162
2163 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2164 return blk.result();
2165 }
2166
2167 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2168 switch (cause) {
2169 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2170 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2171 case GCCause::_update_allocation_context_stats_inc: return true;
2172 case GCCause::_wb_conc_mark: return true;
2173 default : return false;
2174 }
2175 }
2176
2177 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2178 switch (cause) {
2179 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2180 case GCCause::_g1_humongous_allocation: return true;
2181 default: return is_user_requested_concurrent_full_gc(cause);
2182 }
2183 }
2184
2185 #ifndef PRODUCT
2186 void G1CollectedHeap::allocate_dummy_regions() {
2187 // Let's fill up most of the region
2188 size_t word_size = HeapRegion::GrainWords - 1024;
2189 // And as a result the region we'll allocate will be humongous.
2190 guarantee(is_humongous(word_size), "sanity");
2191
2192 // _filler_array_max_size is set to humongous object threshold
2193 // but temporarily change it to use CollectedHeap::fill_with_object().
2194 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2195
2196 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2197 // Let's use the existing mechanism for the allocation
2198 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2199 AllocationContext::system());
2200 if (dummy_obj != NULL) {
2201 MemRegion mr(dummy_obj, word_size);
2202 CollectedHeap::fill_with_object(mr);
2203 } else {
2204 // If we can't allocate once, we probably cannot allocate
2205 // again. Let's get out of the loop.
2206 break;
2207 }
2208 }
2209 }
2210 #endif // !PRODUCT
2211
2212 void G1CollectedHeap::increment_old_marking_cycles_started() {
2213 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2214 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2215 "Wrong marking cycle count (started: %d, completed: %d)",
2216 _old_marking_cycles_started, _old_marking_cycles_completed);
2217
2218 _old_marking_cycles_started++;
2219 }
2220
2221 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2222 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2223
2224 // We assume that if concurrent == true, then the caller is a
2225 // concurrent thread that was joined the Suspendible Thread
2226 // Set. If there's ever a cheap way to check this, we should add an
2227 // assert here.
2228
2229 // Given that this method is called at the end of a Full GC or of a
2230 // concurrent cycle, and those can be nested (i.e., a Full GC can
2231 // interrupt a concurrent cycle), the number of full collections
2232 // completed should be either one (in the case where there was no
2233 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2234 // behind the number of full collections started.
2235
2236 // This is the case for the inner caller, i.e. a Full GC.
2237 assert(concurrent ||
2238 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2239 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2240 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2241 "is inconsistent with _old_marking_cycles_completed = %u",
2242 _old_marking_cycles_started, _old_marking_cycles_completed);
2243
2244 // This is the case for the outer caller, i.e. the concurrent cycle.
2245 assert(!concurrent ||
2246 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2247 "for outer caller (concurrent cycle): "
2248 "_old_marking_cycles_started = %u "
2249 "is inconsistent with _old_marking_cycles_completed = %u",
2250 _old_marking_cycles_started, _old_marking_cycles_completed);
2251
2252 _old_marking_cycles_completed += 1;
2253
2254 // We need to clear the "in_progress" flag in the CM thread before
2255 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2256 // is set) so that if a waiter requests another System.gc() it doesn't
2257 // incorrectly see that a marking cycle is still in progress.
2258 if (concurrent) {
2259 _cmThread->set_idle();
2260 }
2261
2262 // This notify_all() will ensure that a thread that called
2263 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2264 // and it's waiting for a full GC to finish will be woken up. It is
2265 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2266 FullGCCount_lock->notify_all();
2267 }
2268
2269 void G1CollectedHeap::collect(GCCause::Cause cause) {
2270 assert_heap_not_locked();
2271
2272 uint gc_count_before;
2273 uint old_marking_count_before;
2274 uint full_gc_count_before;
2275 bool retry_gc;
2276
2277 do {
2278 retry_gc = false;
2279
2280 {
2281 MutexLocker ml(Heap_lock);
2282
2283 // Read the GC count while holding the Heap_lock
2284 gc_count_before = total_collections();
2285 full_gc_count_before = total_full_collections();
2286 old_marking_count_before = _old_marking_cycles_started;
2287 }
2288
2289 if (should_do_concurrent_full_gc(cause)) {
2290 // Schedule an initial-mark evacuation pause that will start a
2291 // concurrent cycle. We're setting word_size to 0 which means that
2292 // we are not requesting a post-GC allocation.
2293 VM_G1IncCollectionPause op(gc_count_before,
2294 0, /* word_size */
2295 true, /* should_initiate_conc_mark */
2296 g1_policy()->max_pause_time_ms(),
2297 cause);
2298 op.set_allocation_context(AllocationContext::current());
2299
2300 VMThread::execute(&op);
2301 if (!op.pause_succeeded()) {
2302 if (old_marking_count_before == _old_marking_cycles_started) {
2303 retry_gc = op.should_retry_gc();
2304 } else {
2305 // A Full GC happened while we were trying to schedule the
2306 // initial-mark GC. No point in starting a new cycle given
2307 // that the whole heap was collected anyway.
2308 }
2309
2310 if (retry_gc) {
2311 if (GCLocker::is_active_and_needs_gc()) {
2312 GCLocker::stall_until_clear();
2313 }
2314 }
2315 }
2316 } else {
2317 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2318 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2319
2320 // Schedule a standard evacuation pause. We're setting word_size
2321 // to 0 which means that we are not requesting a post-GC allocation.
2322 VM_G1IncCollectionPause op(gc_count_before,
2323 0, /* word_size */
2324 false, /* should_initiate_conc_mark */
2325 g1_policy()->max_pause_time_ms(),
2326 cause);
2327 VMThread::execute(&op);
2328 } else {
2329 // Schedule a Full GC.
2330 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2331 VMThread::execute(&op);
2332 }
2333 }
2334 } while (retry_gc);
2335 }
2336
2337 bool G1CollectedHeap::is_in(const void* p) const {
2338 if (_hrm.reserved().contains(p)) {
2339 // Given that we know that p is in the reserved space,
2340 // heap_region_containing() should successfully
2341 // return the containing region.
2342 HeapRegion* hr = heap_region_containing(p);
2343 return hr->is_in(p);
2344 } else {
2345 return false;
2346 }
2347 }
2348
2349 #ifdef ASSERT
2350 bool G1CollectedHeap::is_in_exact(const void* p) const {
2351 bool contains = reserved_region().contains(p);
2352 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2353 if (contains && available) {
2354 return true;
2355 } else {
2356 return false;
2357 }
2358 }
2359 #endif
2360
2361 // Iteration functions.
2362
2363 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2364
2365 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2366 ExtendedOopClosure* _cl;
2367 public:
2368 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2369 bool doHeapRegion(HeapRegion* r) {
2370 if (!r->is_continues_humongous()) {
2371 r->oop_iterate(_cl);
2372 }
2373 return false;
2374 }
2375 };
2376
2377 // Iterates an ObjectClosure over all objects within a HeapRegion.
2378
2379 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2380 ObjectClosure* _cl;
2381 public:
2382 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2383 bool doHeapRegion(HeapRegion* r) {
2384 if (!r->is_continues_humongous()) {
2385 r->object_iterate(_cl);
2386 }
2387 return false;
2388 }
2389 };
2390
2391 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2392 IterateObjectClosureRegionClosure blk(cl);
2393 heap_region_iterate(&blk);
2394 }
2395
2396 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2397 _hrm.iterate(cl);
2398 }
2399
2400 void
2401 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2402 uint worker_id,
2403 HeapRegionClaimer *hrclaimer,
2404 bool concurrent) const {
2405 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2406 }
2407
2408 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2409 _collection_set.iterate(cl);
2410 }
2411
2412 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2413 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2414 }
2415
2416 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2417 HeapRegion* result = _hrm.next_region_in_heap(from);
2418 while (result != NULL && result->is_pinned()) {
2419 result = _hrm.next_region_in_heap(result);
2420 }
2421 return result;
2422 }
2423
2424 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2425 HeapRegion* hr = heap_region_containing(addr);
2426 return hr->block_start(addr);
2427 }
2428
2429 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2430 HeapRegion* hr = heap_region_containing(addr);
2431 return hr->block_size(addr);
2432 }
2433
2434 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2435 HeapRegion* hr = heap_region_containing(addr);
2436 return hr->block_is_obj(addr);
2437 }
2438
2439 bool G1CollectedHeap::supports_tlab_allocation() const {
2440 return true;
2441 }
2442
2443 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2444 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2445 }
2446
2447 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2448 return _eden.length() * HeapRegion::GrainBytes;
2449 }
2450
2451 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2452 // must be equal to the humongous object limit.
2453 size_t G1CollectedHeap::max_tlab_size() const {
2454 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2455 }
2456
2457 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2458 AllocationContext_t context = AllocationContext::current();
2459 return _allocator->unsafe_max_tlab_alloc(context);
2460 }
2461
2462 size_t G1CollectedHeap::max_capacity() const {
2463 return _hrm.reserved().byte_size();
2464 }
2465
2466 jlong G1CollectedHeap::millis_since_last_gc() {
2467 // See the notes in GenCollectedHeap::millis_since_last_gc()
2468 // for more information about the implementation.
2469 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2470 _g1_policy->collection_pause_end_millis();
2471 if (ret_val < 0) {
2472 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2473 ". returning zero instead.", ret_val);
2474 return 0;
2475 }
2476 return ret_val;
2477 }
2478
2479 void G1CollectedHeap::prepare_for_verify() {
2480 _verifier->prepare_for_verify();
2481 }
2482
2483 void G1CollectedHeap::verify(VerifyOption vo) {
2484 _verifier->verify(vo);
2485 }
2486
2487 class PrintRegionClosure: public HeapRegionClosure {
2488 outputStream* _st;
2489 public:
2490 PrintRegionClosure(outputStream* st) : _st(st) {}
2491 bool doHeapRegion(HeapRegion* r) {
2492 r->print_on(_st);
2493 return false;
2494 }
2495 };
2496
2497 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2498 const HeapRegion* hr,
2499 const VerifyOption vo) const {
2500 switch (vo) {
2501 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2502 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2503 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2504 default: ShouldNotReachHere();
2505 }
2506 return false; // keep some compilers happy
2507 }
2508
2509 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2510 const VerifyOption vo) const {
2511 switch (vo) {
2512 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2513 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2514 case VerifyOption_G1UseMarkWord: {
2515 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2516 return !obj->is_gc_marked() && !hr->is_archive();
2517 }
2518 default: ShouldNotReachHere();
2519 }
2520 return false; // keep some compilers happy
2521 }
2522
2523 void G1CollectedHeap::print_heap_regions() const {
2524 Log(gc, heap, region) log;
2525 if (log.is_trace()) {
2526 ResourceMark rm;
2527 print_regions_on(log.trace_stream());
2528 }
2529 }
2530
2531 void G1CollectedHeap::print_on(outputStream* st) const {
2532 st->print(" %-20s", "garbage-first heap");
2533 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2534 capacity()/K, used_unlocked()/K);
2535 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2536 p2i(_hrm.reserved().start()),
2537 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2538 p2i(_hrm.reserved().end()));
2539 st->cr();
2540 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2541 uint young_regions = young_regions_count();
2542 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2543 (size_t) young_regions * HeapRegion::GrainBytes / K);
2544 uint survivor_regions = survivor_regions_count();
2545 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2546 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2547 st->cr();
2548 MetaspaceAux::print_on(st);
2549 }
2550
2551 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2552 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2553 "HS=humongous(starts), HC=humongous(continues), "
2554 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2555 "AC=allocation context, "
2556 "TAMS=top-at-mark-start (previous, next)");
2557 PrintRegionClosure blk(st);
2558 heap_region_iterate(&blk);
2559 }
2560
2561 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2562 print_on(st);
2563
2564 // Print the per-region information.
2565 print_regions_on(st);
2566 }
2567
2568 void G1CollectedHeap::print_on_error(outputStream* st) const {
2569 this->CollectedHeap::print_on_error(st);
2570
2571 if (_cm != NULL) {
2572 st->cr();
2573 _cm->print_on_error(st);
2574 }
2575 }
2576
2577 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2578 workers()->print_worker_threads_on(st);
2579 _cmThread->print_on(st);
2580 st->cr();
2581 _cm->print_worker_threads_on(st);
2582 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2583 if (G1StringDedup::is_enabled()) {
2584 G1StringDedup::print_worker_threads_on(st);
2585 }
2586 }
2587
2588 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2589 workers()->threads_do(tc);
2590 tc->do_thread(_cmThread);
2591 _cm->threads_do(tc);
2592 _cg1r->threads_do(tc); // also iterates over the sample thread
2593 if (G1StringDedup::is_enabled()) {
2594 G1StringDedup::threads_do(tc);
2595 }
2596 }
2597
2598 void G1CollectedHeap::print_tracing_info() const {
2599 g1_rem_set()->print_summary_info();
2600 concurrent_mark()->print_summary_info();
2601 }
2602
2603 #ifndef PRODUCT
2604 // Helpful for debugging RSet issues.
2605
2606 class PrintRSetsClosure : public HeapRegionClosure {
2607 private:
2608 const char* _msg;
2609 size_t _occupied_sum;
2610
2611 public:
2612 bool doHeapRegion(HeapRegion* r) {
2613 HeapRegionRemSet* hrrs = r->rem_set();
2614 size_t occupied = hrrs->occupied();
2615 _occupied_sum += occupied;
2616
2617 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2618 if (occupied == 0) {
2619 tty->print_cr(" RSet is empty");
2620 } else {
2621 hrrs->print();
2622 }
2623 tty->print_cr("----------");
2624 return false;
2625 }
2626
2627 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2628 tty->cr();
2629 tty->print_cr("========================================");
2630 tty->print_cr("%s", msg);
2631 tty->cr();
2632 }
2633
2634 ~PrintRSetsClosure() {
2635 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2636 tty->print_cr("========================================");
2637 tty->cr();
2638 }
2639 };
2640
2641 void G1CollectedHeap::print_cset_rsets() {
2642 PrintRSetsClosure cl("Printing CSet RSets");
2643 collection_set_iterate(&cl);
2644 }
2645
2646 void G1CollectedHeap::print_all_rsets() {
2647 PrintRSetsClosure cl("Printing All RSets");;
2648 heap_region_iterate(&cl);
2649 }
2650 #endif // PRODUCT
2651
2652 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2653
2654 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2655 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2656 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2657
2658 size_t eden_capacity_bytes =
2659 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2660
2661 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2662 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2663 eden_capacity_bytes, survivor_used_bytes, num_regions());
2664 }
2665
2666 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2667 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2668 stats->unused(), stats->used(), stats->region_end_waste(),
2669 stats->regions_filled(), stats->direct_allocated(),
2670 stats->failure_used(), stats->failure_waste());
2671 }
2672
2673 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2674 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2675 gc_tracer->report_gc_heap_summary(when, heap_summary);
2676
2677 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2678 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2679 }
2680
2681 G1CollectedHeap* G1CollectedHeap::heap() {
2682 CollectedHeap* heap = Universe::heap();
2683 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2684 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2685 return (G1CollectedHeap*)heap;
2686 }
2687
2688 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2689 // always_do_update_barrier = false;
2690 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2691
2692 double start = os::elapsedTime();
2693 // Fill TLAB's and such
2694 accumulate_statistics_all_tlabs();
2695 ensure_parsability(true);
2696 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2697
2698 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2699 }
2700
2701 void G1CollectedHeap::gc_epilogue(bool full) {
2702 // we are at the end of the GC. Total collections has already been increased.
2703 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2704
2705 // FIXME: what is this about?
2706 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2707 // is set.
2708 #if defined(COMPILER2) || INCLUDE_JVMCI
2709 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2710 #endif
2711 // always_do_update_barrier = true;
2712
2713 double start = os::elapsedTime();
2714 resize_all_tlabs();
2715 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2716
2717 allocation_context_stats().update(full);
2718
2719 // We have just completed a GC. Update the soft reference
2720 // policy with the new heap occupancy
2721 Universe::update_heap_info_at_gc();
2722 }
2723
2724 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2725 uint gc_count_before,
2726 bool* succeeded,
2727 GCCause::Cause gc_cause) {
2728 assert_heap_not_locked_and_not_at_safepoint();
2729 VM_G1IncCollectionPause op(gc_count_before,
2730 word_size,
2731 false, /* should_initiate_conc_mark */
2732 g1_policy()->max_pause_time_ms(),
2733 gc_cause);
2734
2735 op.set_allocation_context(AllocationContext::current());
2736 VMThread::execute(&op);
2737
2738 HeapWord* result = op.result();
2739 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2740 assert(result == NULL || ret_succeeded,
2741 "the result should be NULL if the VM did not succeed");
2742 *succeeded = ret_succeeded;
2743
2744 assert_heap_not_locked();
2745 return result;
2746 }
2747
2748 void
2749 G1CollectedHeap::doConcurrentMark() {
2750 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2751 if (!_cmThread->in_progress()) {
2752 _cmThread->set_started();
2753 CGC_lock->notify();
2754 }
2755 }
2756
2757 size_t G1CollectedHeap::pending_card_num() {
2758 size_t extra_cards = 0;
2759 JavaThread *curr = Threads::first();
2760 while (curr != NULL) {
2761 DirtyCardQueue& dcq = curr->dirty_card_queue();
2762 extra_cards += dcq.size();
2763 curr = curr->next();
2764 }
2765 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2766 size_t buffer_size = dcqs.buffer_size();
2767 size_t buffer_num = dcqs.completed_buffers_num();
2768
2769 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2770 // in bytes - not the number of 'entries'. We need to convert
2771 // into a number of cards.
2772 return (buffer_size * buffer_num + extra_cards) / oopSize;
2773 }
2774
2775 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2776 private:
2777 size_t _total_humongous;
2778 size_t _candidate_humongous;
2779
2780 DirtyCardQueue _dcq;
2781
2782 // We don't nominate objects with many remembered set entries, on
2783 // the assumption that such objects are likely still live.
2784 bool is_remset_small(HeapRegion* region) const {
2785 HeapRegionRemSet* const rset = region->rem_set();
2786 return G1EagerReclaimHumongousObjectsWithStaleRefs
2787 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2788 : rset->is_empty();
2789 }
2790
2791 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2792 assert(region->is_starts_humongous(), "Must start a humongous object");
2793
2794 oop obj = oop(region->bottom());
2795
2796 // Dead objects cannot be eager reclaim candidates. Due to class
2797 // unloading it is unsafe to query their classes so we return early.
2798 if (heap->is_obj_dead(obj, region)) {
2799 return false;
2800 }
2801
2802 // Candidate selection must satisfy the following constraints
2803 // while concurrent marking is in progress:
2804 //
2805 // * In order to maintain SATB invariants, an object must not be
2806 // reclaimed if it was allocated before the start of marking and
2807 // has not had its references scanned. Such an object must have
2808 // its references (including type metadata) scanned to ensure no
2809 // live objects are missed by the marking process. Objects
2810 // allocated after the start of concurrent marking don't need to
2811 // be scanned.
2812 //
2813 // * An object must not be reclaimed if it is on the concurrent
2814 // mark stack. Objects allocated after the start of concurrent
2815 // marking are never pushed on the mark stack.
2816 //
2817 // Nominating only objects allocated after the start of concurrent
2818 // marking is sufficient to meet both constraints. This may miss
2819 // some objects that satisfy the constraints, but the marking data
2820 // structures don't support efficiently performing the needed
2821 // additional tests or scrubbing of the mark stack.
2822 //
2823 // However, we presently only nominate is_typeArray() objects.
2824 // A humongous object containing references induces remembered
2825 // set entries on other regions. In order to reclaim such an
2826 // object, those remembered sets would need to be cleaned up.
2827 //
2828 // We also treat is_typeArray() objects specially, allowing them
2829 // to be reclaimed even if allocated before the start of
2830 // concurrent mark. For this we rely on mark stack insertion to
2831 // exclude is_typeArray() objects, preventing reclaiming an object
2832 // that is in the mark stack. We also rely on the metadata for
2833 // such objects to be built-in and so ensured to be kept live.
2834 // Frequent allocation and drop of large binary blobs is an
2835 // important use case for eager reclaim, and this special handling
2836 // may reduce needed headroom.
2837
2838 return obj->is_typeArray() && is_remset_small(region);
2839 }
2840
2841 public:
2842 RegisterHumongousWithInCSetFastTestClosure()
2843 : _total_humongous(0),
2844 _candidate_humongous(0),
2845 _dcq(&JavaThread::dirty_card_queue_set()) {
2846 }
2847
2848 virtual bool doHeapRegion(HeapRegion* r) {
2849 if (!r->is_starts_humongous()) {
2850 return false;
2851 }
2852 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2853
2854 bool is_candidate = humongous_region_is_candidate(g1h, r);
2855 uint rindex = r->hrm_index();
2856 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2857 if (is_candidate) {
2858 _candidate_humongous++;
2859 g1h->register_humongous_region_with_cset(rindex);
2860 // Is_candidate already filters out humongous object with large remembered sets.
2861 // If we have a humongous object with a few remembered sets, we simply flush these
2862 // remembered set entries into the DCQS. That will result in automatic
2863 // re-evaluation of their remembered set entries during the following evacuation
2864 // phase.
2865 if (!r->rem_set()->is_empty()) {
2866 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2867 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2868 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2869 HeapRegionRemSetIterator hrrs(r->rem_set());
2870 size_t card_index;
2871 while (hrrs.has_next(card_index)) {
2872 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2873 // The remembered set might contain references to already freed
2874 // regions. Filter out such entries to avoid failing card table
2875 // verification.
2876 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2877 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2878 *card_ptr = CardTableModRefBS::dirty_card_val();
2879 _dcq.enqueue(card_ptr);
2880 }
2881 }
2882 }
2883 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2884 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2885 hrrs.n_yielded(), r->rem_set()->occupied());
2886 r->rem_set()->clear_locked();
2887 }
2888 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2889 }
2890 _total_humongous++;
2891
2892 return false;
2893 }
2894
2895 size_t total_humongous() const { return _total_humongous; }
2896 size_t candidate_humongous() const { return _candidate_humongous; }
2897
2898 void flush_rem_set_entries() { _dcq.flush(); }
2899 };
2900
2901 void G1CollectedHeap::register_humongous_regions_with_cset() {
2902 if (!G1EagerReclaimHumongousObjects) {
2903 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2904 return;
2905 }
2906 double time = os::elapsed_counter();
2907
2908 // Collect reclaim candidate information and register candidates with cset.
2909 RegisterHumongousWithInCSetFastTestClosure cl;
2910 heap_region_iterate(&cl);
2911
2912 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2913 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2914 cl.total_humongous(),
2915 cl.candidate_humongous());
2916 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2917
2918 // Finally flush all remembered set entries to re-check into the global DCQS.
2919 cl.flush_rem_set_entries();
2920 }
2921
2922 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2923 public:
2924 bool doHeapRegion(HeapRegion* hr) {
2925 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2926 hr->verify_rem_set();
2927 }
2928 return false;
2929 }
2930 };
2931
2932 uint G1CollectedHeap::num_task_queues() const {
2933 return _task_queues->size();
2934 }
2935
2936 #if TASKQUEUE_STATS
2937 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2938 st->print_raw_cr("GC Task Stats");
2939 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2940 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2941 }
2942
2943 void G1CollectedHeap::print_taskqueue_stats() const {
2944 if (!log_is_enabled(Trace, gc, task, stats)) {
2945 return;
2946 }
2947 Log(gc, task, stats) log;
2948 ResourceMark rm;
2949 outputStream* st = log.trace_stream();
2950
2951 print_taskqueue_stats_hdr(st);
2952
2953 TaskQueueStats totals;
2954 const uint n = num_task_queues();
2955 for (uint i = 0; i < n; ++i) {
2956 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2957 totals += task_queue(i)->stats;
2958 }
2959 st->print_raw("tot "); totals.print(st); st->cr();
2960
2961 DEBUG_ONLY(totals.verify());
2962 }
2963
2964 void G1CollectedHeap::reset_taskqueue_stats() {
2965 const uint n = num_task_queues();
2966 for (uint i = 0; i < n; ++i) {
2967 task_queue(i)->stats.reset();
2968 }
2969 }
2970 #endif // TASKQUEUE_STATS
2971
2972 void G1CollectedHeap::wait_for_root_region_scanning() {
2973 double scan_wait_start = os::elapsedTime();
2974 // We have to wait until the CM threads finish scanning the
2975 // root regions as it's the only way to ensure that all the
2976 // objects on them have been correctly scanned before we start
2977 // moving them during the GC.
2978 bool waited = _cm->root_regions()->wait_until_scan_finished();
2979 double wait_time_ms = 0.0;
2980 if (waited) {
2981 double scan_wait_end = os::elapsedTime();
2982 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2983 }
2984 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2985 }
2986
2987 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2988 private:
2989 G1HRPrinter* _hr_printer;
2990 public:
2991 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2992
2993 virtual bool doHeapRegion(HeapRegion* r) {
2994 _hr_printer->cset(r);
2995 return false;
2996 }
2997 };
2998
2999 void G1CollectedHeap::start_new_collection_set() {
3000 collection_set()->start_incremental_building();
3001
3002 clear_cset_fast_test();
3003
3004 guarantee(_eden.length() == 0, "eden should have been cleared");
3005 g1_policy()->transfer_survivors_to_cset(survivor());
3006 }
3007
3008 bool
3009 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3010 assert_at_safepoint(true /* should_be_vm_thread */);
3011 guarantee(!is_gc_active(), "collection is not reentrant");
3012
3013 if (GCLocker::check_active_before_gc()) {
3014 return false;
3015 }
3016
3017 _gc_timer_stw->register_gc_start();
3018
3019 GCIdMark gc_id_mark;
3020 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3021
3022 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3023 ResourceMark rm;
3024
3025 g1_policy()->note_gc_start();
3026
3027 wait_for_root_region_scanning();
3028
3029 print_heap_before_gc();
3030 print_heap_regions();
3031 trace_heap_before_gc(_gc_tracer_stw);
3032
3033 _verifier->verify_region_sets_optional();
3034 _verifier->verify_dirty_young_regions();
3035
3036 // We should not be doing initial mark unless the conc mark thread is running
3037 if (!_cmThread->should_terminate()) {
3038 // This call will decide whether this pause is an initial-mark
3039 // pause. If it is, during_initial_mark_pause() will return true
3040 // for the duration of this pause.
3041 g1_policy()->decide_on_conc_mark_initiation();
3042 }
3043
3044 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3045 assert(!collector_state()->during_initial_mark_pause() ||
3046 collector_state()->gcs_are_young(), "sanity");
3047
3048 // We also do not allow mixed GCs during marking.
3049 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3050
3051 // Record whether this pause is an initial mark. When the current
3052 // thread has completed its logging output and it's safe to signal
3053 // the CM thread, the flag's value in the policy has been reset.
3054 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3055
3056 // Inner scope for scope based logging, timers, and stats collection
3057 {
3058 EvacuationInfo evacuation_info;
3059
3060 if (collector_state()->during_initial_mark_pause()) {
3061 // We are about to start a marking cycle, so we increment the
3062 // full collection counter.
3063 increment_old_marking_cycles_started();
3064 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3065 }
3066
3067 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3068
3069 GCTraceCPUTime tcpu;
3070
3071 FormatBuffer<> gc_string("Pause ");
3072 if (collector_state()->during_initial_mark_pause()) {
3073 gc_string.append("Initial Mark");
3074 } else if (collector_state()->gcs_are_young()) {
3075 gc_string.append("Young");
3076 } else {
3077 gc_string.append("Mixed");
3078 }
3079 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3080
3081 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3082 workers()->active_workers(),
3083 Threads::number_of_non_daemon_threads());
3084 workers()->update_active_workers(active_workers);
3085 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3086
3087 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3088 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3089
3090 // If the secondary_free_list is not empty, append it to the
3091 // free_list. No need to wait for the cleanup operation to finish;
3092 // the region allocation code will check the secondary_free_list
3093 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3094 // set, skip this step so that the region allocation code has to
3095 // get entries from the secondary_free_list.
3096 if (!G1StressConcRegionFreeing) {
3097 append_secondary_free_list_if_not_empty_with_lock();
3098 }
3099
3100 G1HeapTransition heap_transition(this);
3101 size_t heap_used_bytes_before_gc = used();
3102
3103 // Don't dynamically change the number of GC threads this early. A value of
3104 // 0 is used to indicate serial work. When parallel work is done,
3105 // it will be set.
3106
3107 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3108 IsGCActiveMark x;
3109
3110 gc_prologue(false);
3111 increment_total_collections(false /* full gc */);
3112 increment_gc_time_stamp();
3113
3114 if (VerifyRememberedSets) {
3115 log_info(gc, verify)("[Verifying RemSets before GC]");
3116 VerifyRegionRemSetClosure v_cl;
3117 heap_region_iterate(&v_cl);
3118 }
3119
3120 _verifier->verify_before_gc();
3121
3122 _verifier->check_bitmaps("GC Start");
3123
3124 #if defined(COMPILER2) || INCLUDE_JVMCI
3125 DerivedPointerTable::clear();
3126 #endif
3127
3128 // Please see comment in g1CollectedHeap.hpp and
3129 // G1CollectedHeap::ref_processing_init() to see how
3130 // reference processing currently works in G1.
3131
3132 // Enable discovery in the STW reference processor
3133 if (g1_policy()->should_process_references()) {
3134 ref_processor_stw()->enable_discovery();
3135 } else {
3136 ref_processor_stw()->disable_discovery();
3137 }
3138
3139 {
3140 // We want to temporarily turn off discovery by the
3141 // CM ref processor, if necessary, and turn it back on
3142 // on again later if we do. Using a scoped
3143 // NoRefDiscovery object will do this.
3144 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3145
3146 // Forget the current alloc region (we might even choose it to be part
3147 // of the collection set!).
3148 _allocator->release_mutator_alloc_region();
3149
3150 // This timing is only used by the ergonomics to handle our pause target.
3151 // It is unclear why this should not include the full pause. We will
3152 // investigate this in CR 7178365.
3153 //
3154 // Preserving the old comment here if that helps the investigation:
3155 //
3156 // The elapsed time induced by the start time below deliberately elides
3157 // the possible verification above.
3158 double sample_start_time_sec = os::elapsedTime();
3159
3160 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3161
3162 if (collector_state()->during_initial_mark_pause()) {
3163 concurrent_mark()->checkpointRootsInitialPre();
3164 }
3165
3166 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3167
3168 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3169
3170 // Make sure the remembered sets are up to date. This needs to be
3171 // done before register_humongous_regions_with_cset(), because the
3172 // remembered sets are used there to choose eager reclaim candidates.
3173 // If the remembered sets are not up to date we might miss some
3174 // entries that need to be handled.
3175 g1_rem_set()->cleanupHRRS();
3176
3177 register_humongous_regions_with_cset();
3178
3179 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3180
3181 // We call this after finalize_cset() to
3182 // ensure that the CSet has been finalized.
3183 _cm->verify_no_cset_oops();
3184
3185 if (_hr_printer.is_active()) {
3186 G1PrintCollectionSetClosure cl(&_hr_printer);
3187 _collection_set.iterate(&cl);
3188 }
3189
3190 // Initialize the GC alloc regions.
3191 _allocator->init_gc_alloc_regions(evacuation_info);
3192
3193 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3194 pre_evacuate_collection_set();
3195
3196 // Actually do the work...
3197 evacuate_collection_set(evacuation_info, &per_thread_states);
3198
3199 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3200
3201 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3202 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3203
3204 eagerly_reclaim_humongous_regions();
3205
3206 record_obj_copy_mem_stats();
3207 _survivor_evac_stats.adjust_desired_plab_sz();
3208 _old_evac_stats.adjust_desired_plab_sz();
3209
3210 start_new_collection_set();
3211
3212 if (evacuation_failed()) {
3213 set_used(recalculate_used());
3214 if (_archive_allocator != NULL) {
3215 _archive_allocator->clear_used();
3216 }
3217 for (uint i = 0; i < ParallelGCThreads; i++) {
3218 if (_evacuation_failed_info_array[i].has_failed()) {
3219 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3220 }
3221 }
3222 } else {
3223 // The "used" of the the collection set have already been subtracted
3224 // when they were freed. Add in the bytes evacuated.
3225 increase_used(g1_policy()->bytes_copied_during_gc());
3226 }
3227
3228 if (collector_state()->during_initial_mark_pause()) {
3229 // We have to do this before we notify the CM threads that
3230 // they can start working to make sure that all the
3231 // appropriate initialization is done on the CM object.
3232 concurrent_mark()->checkpointRootsInitialPost();
3233 collector_state()->set_mark_in_progress(true);
3234 // Note that we don't actually trigger the CM thread at
3235 // this point. We do that later when we're sure that
3236 // the current thread has completed its logging output.
3237 }
3238
3239 allocate_dummy_regions();
3240
3241 _allocator->init_mutator_alloc_region();
3242
3243 {
3244 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3245 if (expand_bytes > 0) {
3246 size_t bytes_before = capacity();
3247 // No need for an ergo logging here,
3248 // expansion_amount() does this when it returns a value > 0.
3249 double expand_ms;
3250 if (!expand(expand_bytes, _workers, &expand_ms)) {
3251 // We failed to expand the heap. Cannot do anything about it.
3252 }
3253 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3254 }
3255 }
3256
3257 // We redo the verification but now wrt to the new CSet which
3258 // has just got initialized after the previous CSet was freed.
3259 _cm->verify_no_cset_oops();
3260
3261 // This timing is only used by the ergonomics to handle our pause target.
3262 // It is unclear why this should not include the full pause. We will
3263 // investigate this in CR 7178365.
3264 double sample_end_time_sec = os::elapsedTime();
3265 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3266 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3267 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3268
3269 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3270 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3271
3272 MemoryService::track_memory_usage();
3273
3274 // In prepare_for_verify() below we'll need to scan the deferred
3275 // update buffers to bring the RSets up-to-date if
3276 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3277 // the update buffers we'll probably need to scan cards on the
3278 // regions we just allocated to (i.e., the GC alloc
3279 // regions). However, during the last GC we called
3280 // set_saved_mark() on all the GC alloc regions, so card
3281 // scanning might skip the [saved_mark_word()...top()] area of
3282 // those regions (i.e., the area we allocated objects into
3283 // during the last GC). But it shouldn't. Given that
3284 // saved_mark_word() is conditional on whether the GC time stamp
3285 // on the region is current or not, by incrementing the GC time
3286 // stamp here we invalidate all the GC time stamps on all the
3287 // regions and saved_mark_word() will simply return top() for
3288 // all the regions. This is a nicer way of ensuring this rather
3289 // than iterating over the regions and fixing them. In fact, the
3290 // GC time stamp increment here also ensures that
3291 // saved_mark_word() will return top() between pauses, i.e.,
3292 // during concurrent refinement. So we don't need the
3293 // is_gc_active() check to decided which top to use when
3294 // scanning cards (see CR 7039627).
3295 increment_gc_time_stamp();
3296
3297 if (VerifyRememberedSets) {
3298 log_info(gc, verify)("[Verifying RemSets after GC]");
3299 VerifyRegionRemSetClosure v_cl;
3300 heap_region_iterate(&v_cl);
3301 }
3302
3303 _verifier->verify_after_gc();
3304 _verifier->check_bitmaps("GC End");
3305
3306 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3307 ref_processor_stw()->verify_no_references_recorded();
3308
3309 // CM reference discovery will be re-enabled if necessary.
3310 }
3311
3312 #ifdef TRACESPINNING
3313 ParallelTaskTerminator::print_termination_counts();
3314 #endif
3315
3316 gc_epilogue(false);
3317 }
3318
3319 // Print the remainder of the GC log output.
3320 if (evacuation_failed()) {
3321 log_info(gc)("To-space exhausted");
3322 }
3323
3324 g1_policy()->print_phases();
3325 heap_transition.print();
3326
3327 // It is not yet to safe to tell the concurrent mark to
3328 // start as we have some optional output below. We don't want the
3329 // output from the concurrent mark thread interfering with this
3330 // logging output either.
3331
3332 _hrm.verify_optional();
3333 _verifier->verify_region_sets_optional();
3334
3335 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3336 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3337
3338 print_heap_after_gc();
3339 print_heap_regions();
3340 trace_heap_after_gc(_gc_tracer_stw);
3341
3342 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3343 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3344 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3345 // before any GC notifications are raised.
3346 g1mm()->update_sizes();
3347
3348 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3349 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3350 _gc_timer_stw->register_gc_end();
3351 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3352 }
3353 // It should now be safe to tell the concurrent mark thread to start
3354 // without its logging output interfering with the logging output
3355 // that came from the pause.
3356
3357 if (should_start_conc_mark) {
3358 // CAUTION: after the doConcurrentMark() call below,
3359 // the concurrent marking thread(s) could be running
3360 // concurrently with us. Make sure that anything after
3361 // this point does not assume that we are the only GC thread
3362 // running. Note: of course, the actual marking work will
3363 // not start until the safepoint itself is released in
3364 // SuspendibleThreadSet::desynchronize().
3365 doConcurrentMark();
3366 }
3367
3368 return true;
3369 }
3370
3371 void G1CollectedHeap::remove_self_forwarding_pointers() {
3372 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3373 workers()->run_task(&rsfp_task);
3374 }
3375
3376 void G1CollectedHeap::restore_after_evac_failure() {
3377 double remove_self_forwards_start = os::elapsedTime();
3378
3379 remove_self_forwarding_pointers();
3380 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3381 _preserved_marks_set.restore(&task_executor);
3382
3383 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3384 }
3385
3386 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3387 if (!_evacuation_failed) {
3388 _evacuation_failed = true;
3389 }
3390
3391 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3392 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3393 }
3394
3395 bool G1ParEvacuateFollowersClosure::offer_termination() {
3396 G1ParScanThreadState* const pss = par_scan_state();
3397 start_term_time();
3398 const bool res = terminator()->offer_termination();
3399 end_term_time();
3400 return res;
3401 }
3402
3403 void G1ParEvacuateFollowersClosure::do_void() {
3404 G1ParScanThreadState* const pss = par_scan_state();
3405 pss->trim_queue();
3406 do {
3407 pss->steal_and_trim_queue(queues());
3408 } while (!offer_termination());
3409 }
3410
3411 class G1ParTask : public AbstractGangTask {
3412 protected:
3413 G1CollectedHeap* _g1h;
3414 G1ParScanThreadStateSet* _pss;
3415 RefToScanQueueSet* _queues;
3416 G1RootProcessor* _root_processor;
3417 ParallelTaskTerminator _terminator;
3418 uint _n_workers;
3419
3420 public:
3421 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3422 : AbstractGangTask("G1 collection"),
3423 _g1h(g1h),
3424 _pss(per_thread_states),
3425 _queues(task_queues),
3426 _root_processor(root_processor),
3427 _terminator(n_workers, _queues),
3428 _n_workers(n_workers)
3429 {}
3430
3431 void work(uint worker_id) {
3432 if (worker_id >= _n_workers) return; // no work needed this round
3433
3434 double start_sec = os::elapsedTime();
3435 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3436
3437 {
3438 ResourceMark rm;
3439 HandleMark hm;
3440
3441 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3442
3443 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3444 pss->set_ref_processor(rp);
3445
3446 double start_strong_roots_sec = os::elapsedTime();
3447
3448 _root_processor->evacuate_roots(pss->closures(), worker_id);
3449
3450 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3451
3452 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3453 // treating the nmethods visited to act as roots for concurrent marking.
3454 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3455 // objects copied by the current evacuation.
3456 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3457 pss->closures()->weak_codeblobs(),
3458 worker_id);
3459
3460 _pss->add_cards_scanned(worker_id, cards_scanned);
3461
3462 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3463
3464 double term_sec = 0.0;
3465 size_t evac_term_attempts = 0;
3466 {
3467 double start = os::elapsedTime();
3468 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3469 evac.do_void();
3470
3471 evac_term_attempts = evac.term_attempts();
3472 term_sec = evac.term_time();
3473 double elapsed_sec = os::elapsedTime() - start;
3474 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3475 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3476 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3477 }
3478
3479 assert(pss->queue_is_empty(), "should be empty");
3480
3481 if (log_is_enabled(Debug, gc, task, stats)) {
3482 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3483 size_t lab_waste;
3484 size_t lab_undo_waste;
3485 pss->waste(lab_waste, lab_undo_waste);
3486 _g1h->print_termination_stats(worker_id,
3487 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3488 strong_roots_sec * 1000.0, /* strong roots time */
3489 term_sec * 1000.0, /* evac term time */
3490 evac_term_attempts, /* evac term attempts */
3491 lab_waste, /* alloc buffer waste */
3492 lab_undo_waste /* undo waste */
3493 );
3494 }
3495
3496 // Close the inner scope so that the ResourceMark and HandleMark
3497 // destructors are executed here and are included as part of the
3498 // "GC Worker Time".
3499 }
3500 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3501 }
3502 };
3503
3504 void G1CollectedHeap::print_termination_stats_hdr() {
3505 log_debug(gc, task, stats)("GC Termination Stats");
3506 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3507 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3508 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3509 }
3510
3511 void G1CollectedHeap::print_termination_stats(uint worker_id,
3512 double elapsed_ms,
3513 double strong_roots_ms,
3514 double term_ms,
3515 size_t term_attempts,
3516 size_t alloc_buffer_waste,
3517 size_t undo_waste) const {
3518 log_debug(gc, task, stats)
3519 ("%3d %9.2f %9.2f %6.2f "
3520 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3521 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3522 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3523 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3524 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3525 alloc_buffer_waste * HeapWordSize / K,
3526 undo_waste * HeapWordSize / K);
3527 }
3528
3529 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3530 private:
3531 BoolObjectClosure* _is_alive;
3532 int _initial_string_table_size;
3533 int _initial_symbol_table_size;
3534
3535 bool _process_strings;
3536 int _strings_processed;
3537 int _strings_removed;
3538
3539 bool _process_symbols;
3540 int _symbols_processed;
3541 int _symbols_removed;
3542
3543 public:
3544 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3545 AbstractGangTask("String/Symbol Unlinking"),
3546 _is_alive(is_alive),
3547 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3548 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3549
3550 _initial_string_table_size = StringTable::the_table()->table_size();
3551 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3552 if (process_strings) {
3553 StringTable::clear_parallel_claimed_index();
3554 }
3555 if (process_symbols) {
3556 SymbolTable::clear_parallel_claimed_index();
3557 }
3558 }
3559
3560 ~G1StringSymbolTableUnlinkTask() {
3561 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3562 "claim value %d after unlink less than initial string table size %d",
3563 StringTable::parallel_claimed_index(), _initial_string_table_size);
3564 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3565 "claim value %d after unlink less than initial symbol table size %d",
3566 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3567
3568 log_info(gc, stringtable)(
3569 "Cleaned string and symbol table, "
3570 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3571 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3572 strings_processed(), strings_removed(),
3573 symbols_processed(), symbols_removed());
3574 }
3575
3576 void work(uint worker_id) {
3577 int strings_processed = 0;
3578 int strings_removed = 0;
3579 int symbols_processed = 0;
3580 int symbols_removed = 0;
3581 if (_process_strings) {
3582 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3583 Atomic::add(strings_processed, &_strings_processed);
3584 Atomic::add(strings_removed, &_strings_removed);
3585 }
3586 if (_process_symbols) {
3587 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3588 Atomic::add(symbols_processed, &_symbols_processed);
3589 Atomic::add(symbols_removed, &_symbols_removed);
3590 }
3591 }
3592
3593 size_t strings_processed() const { return (size_t)_strings_processed; }
3594 size_t strings_removed() const { return (size_t)_strings_removed; }
3595
3596 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3597 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3598 };
3599
3600 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3601 private:
3602 static Monitor* _lock;
3603
3604 BoolObjectClosure* const _is_alive;
3605 const bool _unloading_occurred;
3606 const uint _num_workers;
3607
3608 // Variables used to claim nmethods.
3609 CompiledMethod* _first_nmethod;
3610 volatile CompiledMethod* _claimed_nmethod;
3611
3612 // The list of nmethods that need to be processed by the second pass.
3613 volatile CompiledMethod* _postponed_list;
3614 volatile uint _num_entered_barrier;
3615
3616 public:
3617 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3618 _is_alive(is_alive),
3619 _unloading_occurred(unloading_occurred),
3620 _num_workers(num_workers),
3621 _first_nmethod(NULL),
3622 _claimed_nmethod(NULL),
3623 _postponed_list(NULL),
3624 _num_entered_barrier(0)
3625 {
3626 CompiledMethod::increase_unloading_clock();
3627 // Get first alive nmethod
3628 CompiledMethodIterator iter = CompiledMethodIterator();
3629 if(iter.next_alive()) {
3630 _first_nmethod = iter.method();
3631 }
3632 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3633 }
3634
3635 ~G1CodeCacheUnloadingTask() {
3636 CodeCache::verify_clean_inline_caches();
3637
3638 CodeCache::set_needs_cache_clean(false);
3639 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3640
3641 CodeCache::verify_icholder_relocations();
3642 }
3643
3644 private:
3645 void add_to_postponed_list(CompiledMethod* nm) {
3646 CompiledMethod* old;
3647 do {
3648 old = (CompiledMethod*)_postponed_list;
3649 nm->set_unloading_next(old);
3650 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3651 }
3652
3653 void clean_nmethod(CompiledMethod* nm) {
3654 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3655
3656 if (postponed) {
3657 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3658 add_to_postponed_list(nm);
3659 }
3660
3661 // Mark that this thread has been cleaned/unloaded.
3662 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3663 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3664 }
3665
3666 void clean_nmethod_postponed(CompiledMethod* nm) {
3667 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3668 }
3669
3670 static const int MaxClaimNmethods = 16;
3671
3672 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3673 CompiledMethod* first;
3674 CompiledMethodIterator last;
3675
3676 do {
3677 *num_claimed_nmethods = 0;
3678
3679 first = (CompiledMethod*)_claimed_nmethod;
3680 last = CompiledMethodIterator(first);
3681
3682 if (first != NULL) {
3683
3684 for (int i = 0; i < MaxClaimNmethods; i++) {
3685 if (!last.next_alive()) {
3686 break;
3687 }
3688 claimed_nmethods[i] = last.method();
3689 (*num_claimed_nmethods)++;
3690 }
3691 }
3692
3693 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3694 }
3695
3696 CompiledMethod* claim_postponed_nmethod() {
3697 CompiledMethod* claim;
3698 CompiledMethod* next;
3699
3700 do {
3701 claim = (CompiledMethod*)_postponed_list;
3702 if (claim == NULL) {
3703 return NULL;
3704 }
3705
3706 next = claim->unloading_next();
3707
3708 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3709
3710 return claim;
3711 }
3712
3713 public:
3714 // Mark that we're done with the first pass of nmethod cleaning.
3715 void barrier_mark(uint worker_id) {
3716 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3717 _num_entered_barrier++;
3718 if (_num_entered_barrier == _num_workers) {
3719 ml.notify_all();
3720 }
3721 }
3722
3723 // See if we have to wait for the other workers to
3724 // finish their first-pass nmethod cleaning work.
3725 void barrier_wait(uint worker_id) {
3726 if (_num_entered_barrier < _num_workers) {
3727 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3728 while (_num_entered_barrier < _num_workers) {
3729 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3730 }
3731 }
3732 }
3733
3734 // Cleaning and unloading of nmethods. Some work has to be postponed
3735 // to the second pass, when we know which nmethods survive.
3736 void work_first_pass(uint worker_id) {
3737 // The first nmethods is claimed by the first worker.
3738 if (worker_id == 0 && _first_nmethod != NULL) {
3739 clean_nmethod(_first_nmethod);
3740 _first_nmethod = NULL;
3741 }
3742
3743 int num_claimed_nmethods;
3744 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3745
3746 while (true) {
3747 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3748
3749 if (num_claimed_nmethods == 0) {
3750 break;
3751 }
3752
3753 for (int i = 0; i < num_claimed_nmethods; i++) {
3754 clean_nmethod(claimed_nmethods[i]);
3755 }
3756 }
3757 }
3758
3759 void work_second_pass(uint worker_id) {
3760 CompiledMethod* nm;
3761 // Take care of postponed nmethods.
3762 while ((nm = claim_postponed_nmethod()) != NULL) {
3763 clean_nmethod_postponed(nm);
3764 }
3765 }
3766 };
3767
3768 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3769
3770 class G1KlassCleaningTask : public StackObj {
3771 BoolObjectClosure* _is_alive;
3772 volatile jint _clean_klass_tree_claimed;
3773 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3774
3775 public:
3776 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3777 _is_alive(is_alive),
3778 _clean_klass_tree_claimed(0),
3779 _klass_iterator() {
3780 }
3781
3782 private:
3783 bool claim_clean_klass_tree_task() {
3784 if (_clean_klass_tree_claimed) {
3785 return false;
3786 }
3787
3788 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3789 }
3790
3791 InstanceKlass* claim_next_klass() {
3792 Klass* klass;
3793 do {
3794 klass =_klass_iterator.next_klass();
3795 } while (klass != NULL && !klass->is_instance_klass());
3796
3797 // this can be null so don't call InstanceKlass::cast
3798 return static_cast<InstanceKlass*>(klass);
3799 }
3800
3801 public:
3802
3803 void clean_klass(InstanceKlass* ik) {
3804 ik->clean_weak_instanceklass_links(_is_alive);
3805 }
3806
3807 void work() {
3808 ResourceMark rm;
3809
3810 // One worker will clean the subklass/sibling klass tree.
3811 if (claim_clean_klass_tree_task()) {
3812 Klass::clean_subklass_tree(_is_alive);
3813 }
3814
3815 // All workers will help cleaning the classes,
3816 InstanceKlass* klass;
3817 while ((klass = claim_next_klass()) != NULL) {
3818 clean_klass(klass);
3819 }
3820 }
3821 };
3822
3823 // To minimize the remark pause times, the tasks below are done in parallel.
3824 class G1ParallelCleaningTask : public AbstractGangTask {
3825 private:
3826 G1StringSymbolTableUnlinkTask _string_symbol_task;
3827 G1CodeCacheUnloadingTask _code_cache_task;
3828 G1KlassCleaningTask _klass_cleaning_task;
3829
3830 public:
3831 // The constructor is run in the VMThread.
3832 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
3833 AbstractGangTask("Parallel Cleaning"),
3834 _string_symbol_task(is_alive, process_strings, process_symbols),
3835 _code_cache_task(num_workers, is_alive, unloading_occurred),
3836 _klass_cleaning_task(is_alive) {
3837 }
3838
3839 // The parallel work done by all worker threads.
3840 void work(uint worker_id) {
3841 // Do first pass of code cache cleaning.
3842 _code_cache_task.work_first_pass(worker_id);
3843
3844 // Let the threads mark that the first pass is done.
3845 _code_cache_task.barrier_mark(worker_id);
3846
3847 // Clean the Strings and Symbols.
3848 _string_symbol_task.work(worker_id);
3849
3850 // Wait for all workers to finish the first code cache cleaning pass.
3851 _code_cache_task.barrier_wait(worker_id);
3852
3853 // Do the second code cache cleaning work, which realize on
3854 // the liveness information gathered during the first pass.
3855 _code_cache_task.work_second_pass(worker_id);
3856
3857 // Clean all klasses that were not unloaded.
3858 _klass_cleaning_task.work();
3859 }
3860 };
3861
3862
3863 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
3864 bool process_strings,
3865 bool process_symbols,
3866 bool class_unloading_occurred) {
3867 uint n_workers = workers()->active_workers();
3868
3869 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
3870 n_workers, class_unloading_occurred);
3871 workers()->run_task(&g1_unlink_task);
3872 }
3873
3874 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
3875 bool process_strings, bool process_symbols) {
3876 { // Timing scope
3877 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
3878 workers()->run_task(&g1_unlink_task);
3879 }
3880 }
3881
3882 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3883 private:
3884 DirtyCardQueueSet* _queue;
3885 G1CollectedHeap* _g1h;
3886 public:
3887 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3888 _queue(queue), _g1h(g1h) { }
3889
3890 virtual void work(uint worker_id) {
3891 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3892 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3893
3894 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3895 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3896
3897 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3898 }
3899 };
3900
3901 void G1CollectedHeap::redirty_logged_cards() {
3902 double redirty_logged_cards_start = os::elapsedTime();
3903
3904 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3905 dirty_card_queue_set().reset_for_par_iteration();
3906 workers()->run_task(&redirty_task);
3907
3908 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3909 dcq.merge_bufferlists(&dirty_card_queue_set());
3910 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3911
3912 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3913 }
3914
3915 // Weak Reference Processing support
3916
3917 // An always "is_alive" closure that is used to preserve referents.
3918 // If the object is non-null then it's alive. Used in the preservation
3919 // of referent objects that are pointed to by reference objects
3920 // discovered by the CM ref processor.
3921 class G1AlwaysAliveClosure: public BoolObjectClosure {
3922 G1CollectedHeap* _g1;
3923 public:
3924 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3925 bool do_object_b(oop p) {
3926 if (p != NULL) {
3927 return true;
3928 }
3929 return false;
3930 }
3931 };
3932
3933 bool G1STWIsAliveClosure::do_object_b(oop p) {
3934 // An object is reachable if it is outside the collection set,
3935 // or is inside and copied.
3936 return !_g1->is_in_cset(p) || p->is_forwarded();
3937 }
3938
3939 // Non Copying Keep Alive closure
3940 class G1KeepAliveClosure: public OopClosure {
3941 G1CollectedHeap* _g1;
3942 public:
3943 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3944 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3945 void do_oop(oop* p) {
3946 oop obj = *p;
3947 assert(obj != NULL, "the caller should have filtered out NULL values");
3948
3949 const InCSetState cset_state = _g1->in_cset_state(obj);
3950 if (!cset_state.is_in_cset_or_humongous()) {
3951 return;
3952 }
3953 if (cset_state.is_in_cset()) {
3954 assert( obj->is_forwarded(), "invariant" );
3955 *p = obj->forwardee();
3956 } else {
3957 assert(!obj->is_forwarded(), "invariant" );
3958 assert(cset_state.is_humongous(),
3959 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3960 _g1->set_humongous_is_live(obj);
3961 }
3962 }
3963 };
3964
3965 // Copying Keep Alive closure - can be called from both
3966 // serial and parallel code as long as different worker
3967 // threads utilize different G1ParScanThreadState instances
3968 // and different queues.
3969
3970 class G1CopyingKeepAliveClosure: public OopClosure {
3971 G1CollectedHeap* _g1h;
3972 OopClosure* _copy_non_heap_obj_cl;
3973 G1ParScanThreadState* _par_scan_state;
3974
3975 public:
3976 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3977 OopClosure* non_heap_obj_cl,
3978 G1ParScanThreadState* pss):
3979 _g1h(g1h),
3980 _copy_non_heap_obj_cl(non_heap_obj_cl),
3981 _par_scan_state(pss)
3982 {}
3983
3984 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3985 virtual void do_oop( oop* p) { do_oop_work(p); }
3986
3987 template <class T> void do_oop_work(T* p) {
3988 oop obj = oopDesc::load_decode_heap_oop(p);
3989
3990 if (_g1h->is_in_cset_or_humongous(obj)) {
3991 // If the referent object has been forwarded (either copied
3992 // to a new location or to itself in the event of an
3993 // evacuation failure) then we need to update the reference
3994 // field and, if both reference and referent are in the G1
3995 // heap, update the RSet for the referent.
3996 //
3997 // If the referent has not been forwarded then we have to keep
3998 // it alive by policy. Therefore we have copy the referent.
3999 //
4000 // If the reference field is in the G1 heap then we can push
4001 // on the PSS queue. When the queue is drained (after each
4002 // phase of reference processing) the object and it's followers
4003 // will be copied, the reference field set to point to the
4004 // new location, and the RSet updated. Otherwise we need to
4005 // use the the non-heap or metadata closures directly to copy
4006 // the referent object and update the pointer, while avoiding
4007 // updating the RSet.
4008
4009 if (_g1h->is_in_g1_reserved(p)) {
4010 _par_scan_state->push_on_queue(p);
4011 } else {
4012 assert(!Metaspace::contains((const void*)p),
4013 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4014 _copy_non_heap_obj_cl->do_oop(p);
4015 }
4016 }
4017 }
4018 };
4019
4020 // Serial drain queue closure. Called as the 'complete_gc'
4021 // closure for each discovered list in some of the
4022 // reference processing phases.
4023
4024 class G1STWDrainQueueClosure: public VoidClosure {
4025 protected:
4026 G1CollectedHeap* _g1h;
4027 G1ParScanThreadState* _par_scan_state;
4028
4029 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4030
4031 public:
4032 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4033 _g1h(g1h),
4034 _par_scan_state(pss)
4035 { }
4036
4037 void do_void() {
4038 G1ParScanThreadState* const pss = par_scan_state();
4039 pss->trim_queue();
4040 }
4041 };
4042
4043 // Parallel Reference Processing closures
4044
4045 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4046 // processing during G1 evacuation pauses.
4047
4048 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4049 private:
4050 G1CollectedHeap* _g1h;
4051 G1ParScanThreadStateSet* _pss;
4052 RefToScanQueueSet* _queues;
4053 WorkGang* _workers;
4054 uint _active_workers;
4055
4056 public:
4057 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4058 G1ParScanThreadStateSet* per_thread_states,
4059 WorkGang* workers,
4060 RefToScanQueueSet *task_queues,
4061 uint n_workers) :
4062 _g1h(g1h),
4063 _pss(per_thread_states),
4064 _queues(task_queues),
4065 _workers(workers),
4066 _active_workers(n_workers)
4067 {
4068 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4069 }
4070
4071 // Executes the given task using concurrent marking worker threads.
4072 virtual void execute(ProcessTask& task);
4073 virtual void execute(EnqueueTask& task);
4074 };
4075
4076 // Gang task for possibly parallel reference processing
4077
4078 class G1STWRefProcTaskProxy: public AbstractGangTask {
4079 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4080 ProcessTask& _proc_task;
4081 G1CollectedHeap* _g1h;
4082 G1ParScanThreadStateSet* _pss;
4083 RefToScanQueueSet* _task_queues;
4084 ParallelTaskTerminator* _terminator;
4085
4086 public:
4087 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4088 G1CollectedHeap* g1h,
4089 G1ParScanThreadStateSet* per_thread_states,
4090 RefToScanQueueSet *task_queues,
4091 ParallelTaskTerminator* terminator) :
4092 AbstractGangTask("Process reference objects in parallel"),
4093 _proc_task(proc_task),
4094 _g1h(g1h),
4095 _pss(per_thread_states),
4096 _task_queues(task_queues),
4097 _terminator(terminator)
4098 {}
4099
4100 virtual void work(uint worker_id) {
4101 // The reference processing task executed by a single worker.
4102 ResourceMark rm;
4103 HandleMark hm;
4104
4105 G1STWIsAliveClosure is_alive(_g1h);
4106
4107 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4108 pss->set_ref_processor(NULL);
4109
4110 // Keep alive closure.
4111 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4112
4113 // Complete GC closure
4114 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4115
4116 // Call the reference processing task's work routine.
4117 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4118
4119 // Note we cannot assert that the refs array is empty here as not all
4120 // of the processing tasks (specifically phase2 - pp2_work) execute
4121 // the complete_gc closure (which ordinarily would drain the queue) so
4122 // the queue may not be empty.
4123 }
4124 };
4125
4126 // Driver routine for parallel reference processing.
4127 // Creates an instance of the ref processing gang
4128 // task and has the worker threads execute it.
4129 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4130 assert(_workers != NULL, "Need parallel worker threads.");
4131
4132 ParallelTaskTerminator terminator(_active_workers, _queues);
4133 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4134
4135 _workers->run_task(&proc_task_proxy);
4136 }
4137
4138 // Gang task for parallel reference enqueueing.
4139
4140 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4141 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4142 EnqueueTask& _enq_task;
4143
4144 public:
4145 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4146 AbstractGangTask("Enqueue reference objects in parallel"),
4147 _enq_task(enq_task)
4148 { }
4149
4150 virtual void work(uint worker_id) {
4151 _enq_task.work(worker_id);
4152 }
4153 };
4154
4155 // Driver routine for parallel reference enqueueing.
4156 // Creates an instance of the ref enqueueing gang
4157 // task and has the worker threads execute it.
4158
4159 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4160 assert(_workers != NULL, "Need parallel worker threads.");
4161
4162 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4163
4164 _workers->run_task(&enq_task_proxy);
4165 }
4166
4167 // End of weak reference support closures
4168
4169 // Abstract task used to preserve (i.e. copy) any referent objects
4170 // that are in the collection set and are pointed to by reference
4171 // objects discovered by the CM ref processor.
4172
4173 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4174 protected:
4175 G1CollectedHeap* _g1h;
4176 G1ParScanThreadStateSet* _pss;
4177 RefToScanQueueSet* _queues;
4178 ParallelTaskTerminator _terminator;
4179 uint _n_workers;
4180
4181 public:
4182 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4183 AbstractGangTask("ParPreserveCMReferents"),
4184 _g1h(g1h),
4185 _pss(per_thread_states),
4186 _queues(task_queues),
4187 _terminator(workers, _queues),
4188 _n_workers(workers)
4189 {
4190 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4191 }
4192
4193 void work(uint worker_id) {
4194 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4195
4196 ResourceMark rm;
4197 HandleMark hm;
4198
4199 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4200 pss->set_ref_processor(NULL);
4201 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4202
4203 // Is alive closure
4204 G1AlwaysAliveClosure always_alive(_g1h);
4205
4206 // Copying keep alive closure. Applied to referent objects that need
4207 // to be copied.
4208 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4209
4210 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4211
4212 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4213 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4214
4215 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4216 // So this must be true - but assert just in case someone decides to
4217 // change the worker ids.
4218 assert(worker_id < limit, "sanity");
4219 assert(!rp->discovery_is_atomic(), "check this code");
4220
4221 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4222 for (uint idx = worker_id; idx < limit; idx += stride) {
4223 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4224
4225 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4226 while (iter.has_next()) {
4227 // Since discovery is not atomic for the CM ref processor, we
4228 // can see some null referent objects.
4229 iter.load_ptrs(DEBUG_ONLY(true));
4230 oop ref = iter.obj();
4231
4232 // This will filter nulls.
4233 if (iter.is_referent_alive()) {
4234 iter.make_referent_alive();
4235 }
4236 iter.move_to_next();
4237 }
4238 }
4239
4240 // Drain the queue - which may cause stealing
4241 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4242 drain_queue.do_void();
4243 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4244 assert(pss->queue_is_empty(), "should be");
4245 }
4246 };
4247
4248 void G1CollectedHeap::process_weak_jni_handles() {
4249 double ref_proc_start = os::elapsedTime();
4250
4251 G1STWIsAliveClosure is_alive(this);
4252 G1KeepAliveClosure keep_alive(this);
4253 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4254
4255 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4256 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4257 }
4258
4259 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4260 // Any reference objects, in the collection set, that were 'discovered'
4261 // by the CM ref processor should have already been copied (either by
4262 // applying the external root copy closure to the discovered lists, or
4263 // by following an RSet entry).
4264 //
4265 // But some of the referents, that are in the collection set, that these
4266 // reference objects point to may not have been copied: the STW ref
4267 // processor would have seen that the reference object had already
4268 // been 'discovered' and would have skipped discovering the reference,
4269 // but would not have treated the reference object as a regular oop.
4270 // As a result the copy closure would not have been applied to the
4271 // referent object.
4272 //
4273 // We need to explicitly copy these referent objects - the references
4274 // will be processed at the end of remarking.
4275 //
4276 // We also need to do this copying before we process the reference
4277 // objects discovered by the STW ref processor in case one of these
4278 // referents points to another object which is also referenced by an
4279 // object discovered by the STW ref processor.
4280 double preserve_cm_referents_time = 0.0;
4281
4282 // To avoid spawning task when there is no work to do, check that
4283 // a concurrent cycle is active and that some references have been
4284 // discovered.
4285 if (concurrent_mark()->cmThread()->during_cycle() &&
4286 ref_processor_cm()->has_discovered_references()) {
4287 double preserve_cm_referents_start = os::elapsedTime();
4288 uint no_of_gc_workers = workers()->active_workers();
4289 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4290 per_thread_states,
4291 no_of_gc_workers,
4292 _task_queues);
4293 workers()->run_task(&keep_cm_referents);
4294 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4295 }
4296
4297 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4298 }
4299
4300 // Weak Reference processing during an evacuation pause (part 1).
4301 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4302 double ref_proc_start = os::elapsedTime();
4303
4304 ReferenceProcessor* rp = _ref_processor_stw;
4305 assert(rp->discovery_enabled(), "should have been enabled");
4306
4307 // Closure to test whether a referent is alive.
4308 G1STWIsAliveClosure is_alive(this);
4309
4310 // Even when parallel reference processing is enabled, the processing
4311 // of JNI refs is serial and performed serially by the current thread
4312 // rather than by a worker. The following PSS will be used for processing
4313 // JNI refs.
4314
4315 // Use only a single queue for this PSS.
4316 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4317 pss->set_ref_processor(NULL);
4318 assert(pss->queue_is_empty(), "pre-condition");
4319
4320 // Keep alive closure.
4321 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4322
4323 // Serial Complete GC closure
4324 G1STWDrainQueueClosure drain_queue(this, pss);
4325
4326 // Setup the soft refs policy...
4327 rp->setup_policy(false);
4328
4329 ReferenceProcessorStats stats;
4330 if (!rp->processing_is_mt()) {
4331 // Serial reference processing...
4332 stats = rp->process_discovered_references(&is_alive,
4333 &keep_alive,
4334 &drain_queue,
4335 NULL,
4336 _gc_timer_stw);
4337 } else {
4338 uint no_of_gc_workers = workers()->active_workers();
4339
4340 // Parallel reference processing
4341 assert(no_of_gc_workers <= rp->max_num_q(),
4342 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4343 no_of_gc_workers, rp->max_num_q());
4344
4345 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4346 stats = rp->process_discovered_references(&is_alive,
4347 &keep_alive,
4348 &drain_queue,
4349 &par_task_executor,
4350 _gc_timer_stw);
4351 }
4352
4353 _gc_tracer_stw->report_gc_reference_stats(stats);
4354
4355 // We have completed copying any necessary live referent objects.
4356 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4357
4358 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4359 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4360 }
4361
4362 // Weak Reference processing during an evacuation pause (part 2).
4363 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4364 double ref_enq_start = os::elapsedTime();
4365
4366 ReferenceProcessor* rp = _ref_processor_stw;
4367 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4368
4369 // Now enqueue any remaining on the discovered lists on to
4370 // the pending list.
4371 if (!rp->processing_is_mt()) {
4372 // Serial reference processing...
4373 rp->enqueue_discovered_references();
4374 } else {
4375 // Parallel reference enqueueing
4376
4377 uint n_workers = workers()->active_workers();
4378
4379 assert(n_workers <= rp->max_num_q(),
4380 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4381 n_workers, rp->max_num_q());
4382
4383 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4384 rp->enqueue_discovered_references(&par_task_executor);
4385 }
4386
4387 rp->verify_no_references_recorded();
4388 assert(!rp->discovery_enabled(), "should have been disabled");
4389
4390 // FIXME
4391 // CM's reference processing also cleans up the string and symbol tables.
4392 // Should we do that here also? We could, but it is a serial operation
4393 // and could significantly increase the pause time.
4394
4395 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4396 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4397 }
4398
4399 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4400 double merge_pss_time_start = os::elapsedTime();
4401 per_thread_states->flush();
4402 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4403 }
4404
4405 void G1CollectedHeap::pre_evacuate_collection_set() {
4406 _expand_heap_after_alloc_failure = true;
4407 _evacuation_failed = false;
4408
4409 // Disable the hot card cache.
4410 _hot_card_cache->reset_hot_cache_claimed_index();
4411 _hot_card_cache->set_use_cache(false);
4412
4413 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4414 _preserved_marks_set.assert_empty();
4415 }
4416
4417 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4418 // Should G1EvacuationFailureALot be in effect for this GC?
4419 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4420
4421 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4422
4423 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4424
4425 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4426 if (collector_state()->during_initial_mark_pause()) {
4427 double start_clear_claimed_marks = os::elapsedTime();
4428
4429 ClassLoaderDataGraph::clear_claimed_marks();
4430
4431 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4432 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4433 }
4434
4435 double start_par_time_sec = os::elapsedTime();
4436 double end_par_time_sec;
4437
4438 {
4439 const uint n_workers = workers()->active_workers();
4440 G1RootProcessor root_processor(this, n_workers);
4441 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4442
4443 print_termination_stats_hdr();
4444
4445 workers()->run_task(&g1_par_task);
4446 end_par_time_sec = os::elapsedTime();
4447
4448 // Closing the inner scope will execute the destructor
4449 // for the G1RootProcessor object. We record the current
4450 // elapsed time before closing the scope so that time
4451 // taken for the destructor is NOT included in the
4452 // reported parallel time.
4453 }
4454
4455 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4456 phase_times->record_par_time(par_time_ms);
4457
4458 double code_root_fixup_time_ms =
4459 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4460 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4461 }
4462
4463 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4464 // Process any discovered reference objects - we have
4465 // to do this _before_ we retire the GC alloc regions
4466 // as we may have to copy some 'reachable' referent
4467 // objects (and their reachable sub-graphs) that were
4468 // not copied during the pause.
4469 if (g1_policy()->should_process_references()) {
4470 preserve_cm_referents(per_thread_states);
4471 process_discovered_references(per_thread_states);
4472 } else {
4473 ref_processor_stw()->verify_no_references_recorded();
4474 process_weak_jni_handles();
4475 }
4476
4477 if (G1StringDedup::is_enabled()) {
4478 double fixup_start = os::elapsedTime();
4479
4480 G1STWIsAliveClosure is_alive(this);
4481 G1KeepAliveClosure keep_alive(this);
4482 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4483
4484 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4485 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4486 }
4487
4488 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4489
4490 if (evacuation_failed()) {
4491 restore_after_evac_failure();
4492
4493 // Reset the G1EvacuationFailureALot counters and flags
4494 // Note: the values are reset only when an actual
4495 // evacuation failure occurs.
4496 NOT_PRODUCT(reset_evacuation_should_fail();)
4497 }
4498
4499 _preserved_marks_set.assert_empty();
4500
4501 // Enqueue any remaining references remaining on the STW
4502 // reference processor's discovered lists. We need to do
4503 // this after the card table is cleaned (and verified) as
4504 // the act of enqueueing entries on to the pending list
4505 // will log these updates (and dirty their associated
4506 // cards). We need these updates logged to update any
4507 // RSets.
4508 if (g1_policy()->should_process_references()) {
4509 enqueue_discovered_references(per_thread_states);
4510 } else {
4511 g1_policy()->phase_times()->record_ref_enq_time(0);
4512 }
4513
4514 _allocator->release_gc_alloc_regions(evacuation_info);
4515
4516 merge_per_thread_state_info(per_thread_states);
4517
4518 // Reset and re-enable the hot card cache.
4519 // Note the counts for the cards in the regions in the
4520 // collection set are reset when the collection set is freed.
4521 _hot_card_cache->reset_hot_cache();
4522 _hot_card_cache->set_use_cache(true);
4523
4524 purge_code_root_memory();
4525
4526 redirty_logged_cards();
4527 #if defined(COMPILER2) || INCLUDE_JVMCI
4528 double start = os::elapsedTime();
4529 DerivedPointerTable::update_pointers();
4530 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4531 #endif
4532 g1_policy()->print_age_table();
4533 }
4534
4535 void G1CollectedHeap::record_obj_copy_mem_stats() {
4536 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4537
4538 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4539 create_g1_evac_summary(&_old_evac_stats));
4540 }
4541
4542 void G1CollectedHeap::free_region(HeapRegion* hr,
4543 FreeRegionList* free_list,
4544 bool skip_remset,
4545 bool skip_hot_card_cache,
4546 bool locked) {
4547 assert(!hr->is_free(), "the region should not be free");
4548 assert(!hr->is_empty(), "the region should not be empty");
4549 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4550 assert(free_list != NULL, "pre-condition");
4551
4552 if (G1VerifyBitmaps) {
4553 MemRegion mr(hr->bottom(), hr->end());
4554 concurrent_mark()->clearRangePrevBitmap(mr);
4555 }
4556
4557 // Clear the card counts for this region.
4558 // Note: we only need to do this if the region is not young
4559 // (since we don't refine cards in young regions).
4560 if (!skip_hot_card_cache && !hr->is_young()) {
4561 _hot_card_cache->reset_card_counts(hr);
4562 }
4563 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4564 free_list->add_ordered(hr);
4565 }
4566
4567 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4568 FreeRegionList* free_list,
4569 bool skip_remset) {
4570 assert(hr->is_humongous(), "this is only for humongous regions");
4571 assert(free_list != NULL, "pre-condition");
4572 hr->clear_humongous();
4573 free_region(hr, free_list, skip_remset);
4574 }
4575
4576 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4577 const uint humongous_regions_removed) {
4578 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4579 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4580 _old_set.bulk_remove(old_regions_removed);
4581 _humongous_set.bulk_remove(humongous_regions_removed);
4582 }
4583
4584 }
4585
4586 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4587 assert(list != NULL, "list can't be null");
4588 if (!list->is_empty()) {
4589 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4590 _hrm.insert_list_into_free_list(list);
4591 }
4592 }
4593
4594 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4595 decrease_used(bytes);
4596 }
4597
4598 class G1ParScrubRemSetTask: public G1ParallelizeByRegionsTask {
4599 class G1ScrubRSClosure: public HeapRegionClosure {
4600 G1CardLiveData* _live_data;
4601 public:
4602 G1ScrubRSClosure(G1CardLiveData* live_data) :
4603 _live_data(live_data) {}
4604
4605 bool doHeapRegion(HeapRegion* r) {
4606 if (!r->is_continues_humongous()) {
4607 r->rem_set()->scrub(_live_data);
4608 }
4609 return false;
4610 }
4611 };
4612
4613 public:
4614 G1ParScrubRemSetTask(uint num_workers) :
4615 G1ParallelizeByRegionsTask("G1 ScrubRS", num_workers) {}
4616
4617 void work(uint worker_id) {
4618 G1CollectedHeap* g1 = G1CollectedHeap::heap();
4619 G1ScrubRSClosure scrub_cl(&g1->g1_rem_set()->_card_live_data);
4620 all_heap_regions_work(&scrub_cl, worker_id);
4621 }
4622 };
4623
4624 void G1CollectedHeap::scrub_rem_set() {
4625 uint num_workers = workers()->active_workers();
4626 G1ParScrubRemSetTask g1_par_scrub_rs_task(num_workers);
4627 workers()->run_task(&g1_par_scrub_rs_task);
4628 }
4629
4630 class G1FreeCollectionSetTask : public AbstractGangTask {
4631 private:
4632
4633 // Closure applied to all regions in the collection set to do work that needs to
4634 // be done serially in a single thread.
4635 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4636 private:
4637 EvacuationInfo* _evacuation_info;
4638 const size_t* _surviving_young_words;
4639
4640 // Bytes used in successfully evacuated regions before the evacuation.
4641 size_t _before_used_bytes;
4642 // Bytes used in unsucessfully evacuated regions before the evacuation
4643 size_t _after_used_bytes;
4644
4645 size_t _bytes_allocated_in_old_since_last_gc;
4646
4647 size_t _failure_used_words;
4648 size_t _failure_waste_words;
4649
4650 FreeRegionList _local_free_list;
4651 public:
4652 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4653 HeapRegionClosure(),
4654 _evacuation_info(evacuation_info),
4655 _surviving_young_words(surviving_young_words),
4656 _before_used_bytes(0),
4657 _after_used_bytes(0),
4658 _bytes_allocated_in_old_since_last_gc(0),
4659 _failure_used_words(0),
4660 _failure_waste_words(0),
4661 _local_free_list("Local Region List for CSet Freeing") {
4662 }
4663
4664 virtual bool doHeapRegion(HeapRegion* r) {
4665 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4666
4667 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4668 g1h->clear_in_cset(r);
4669
4670 if (r->is_young()) {
4671 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4672 "Young index %d is wrong for region %u of type %s with %u young regions",
4673 r->young_index_in_cset(),
4674 r->hrm_index(),
4675 r->get_type_str(),
4676 g1h->collection_set()->young_region_length());
4677 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4678 r->record_surv_words_in_group(words_survived);
4679 }
4680
4681 if (!r->evacuation_failed()) {
4682 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4683 _before_used_bytes += r->used();
4684 g1h->free_region(r,
4685 &_local_free_list,
4686 true, /* skip_remset */
4687 true, /* skip_hot_card_cache */
4688 true /* locked */);
4689 } else {
4690 r->uninstall_surv_rate_group();
4691 r->set_young_index_in_cset(-1);
4692 r->set_evacuation_failed(false);
4693 // When moving a young gen region to old gen, we "allocate" that whole region
4694 // there. This is in addition to any already evacuated objects. Notify the
4695 // policy about that.
4696 // Old gen regions do not cause an additional allocation: both the objects
4697 // still in the region and the ones already moved are accounted for elsewhere.
4698 if (r->is_young()) {
4699 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4700 }
4701 // The region is now considered to be old.
4702 r->set_old();
4703 // Do some allocation statistics accounting. Regions that failed evacuation
4704 // are always made old, so there is no need to update anything in the young
4705 // gen statistics, but we need to update old gen statistics.
4706 size_t used_words = r->marked_bytes() / HeapWordSize;
4707
4708 _failure_used_words += used_words;
4709 _failure_waste_words += HeapRegion::GrainWords - used_words;
4710
4711 g1h->old_set_add(r);
4712 _after_used_bytes += r->used();
4713 }
4714 return false;
4715 }
4716
4717 void complete_work() {
4718 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4719
4720 _evacuation_info->set_regions_freed(_local_free_list.length());
4721 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4722
4723 g1h->prepend_to_freelist(&_local_free_list);
4724 g1h->decrement_summary_bytes(_before_used_bytes);
4725
4726 G1Policy* policy = g1h->g1_policy();
4727 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4728
4729 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4730 }
4731 };
4732
4733 G1CollectionSet* _collection_set;
4734 G1SerialFreeCollectionSetClosure _cl;
4735 const size_t* _surviving_young_words;
4736
4737 size_t _rs_lengths;
4738
4739 volatile jint _serial_work_claim;
4740
4741 struct WorkItem {
4742 uint region_idx;
4743 bool is_young;
4744 bool evacuation_failed;
4745
4746 WorkItem(HeapRegion* r) {
4747 region_idx = r->hrm_index();
4748 is_young = r->is_young();
4749 evacuation_failed = r->evacuation_failed();
4750 }
4751 };
4752
4753 volatile size_t _parallel_work_claim;
4754 size_t _num_work_items;
4755 WorkItem* _work_items;
4756
4757 void do_serial_work() {
4758 // Need to grab the lock to be allowed to modify the old region list.
4759 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4760 _collection_set->iterate(&_cl);
4761 }
4762
4763 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4764 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4765
4766 HeapRegion* r = g1h->region_at(region_idx);
4767 assert(!g1h->is_on_master_free_list(r), "sanity");
4768
4769 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4770
4771 if (!is_young) {
4772 g1h->_hot_card_cache->reset_card_counts(r);
4773 }
4774
4775 if (!evacuation_failed) {
4776 r->rem_set()->clear_locked();
4777 }
4778 }
4779
4780 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4781 private:
4782 size_t _cur_idx;
4783 WorkItem* _work_items;
4784 public:
4785 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4786
4787 virtual bool doHeapRegion(HeapRegion* r) {
4788 _work_items[_cur_idx++] = WorkItem(r);
4789 return false;
4790 }
4791 };
4792
4793 void prepare_work() {
4794 G1PrepareFreeCollectionSetClosure cl(_work_items);
4795 _collection_set->iterate(&cl);
4796 }
4797
4798 void complete_work() {
4799 _cl.complete_work();
4800
4801 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4802 policy->record_max_rs_lengths(_rs_lengths);
4803 policy->cset_regions_freed();
4804 }
4805 public:
4806 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4807 AbstractGangTask("G1 Free Collection Set"),
4808 _cl(evacuation_info, surviving_young_words),
4809 _collection_set(collection_set),
4810 _surviving_young_words(surviving_young_words),
4811 _serial_work_claim(0),
4812 _rs_lengths(0),
4813 _parallel_work_claim(0),
4814 _num_work_items(collection_set->region_length()),
4815 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4816 prepare_work();
4817 }
4818
4819 ~G1FreeCollectionSetTask() {
4820 complete_work();
4821 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4822 }
4823
4824 // Chunk size for work distribution. The chosen value has been determined experimentally
4825 // to be a good tradeoff between overhead and achievable parallelism.
4826 static uint chunk_size() { return 32; }
4827
4828 virtual void work(uint worker_id) {
4829 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4830
4831 // Claim serial work.
4832 if (_serial_work_claim == 0) {
4833 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4834 if (value == 0) {
4835 double serial_time = os::elapsedTime();
4836 do_serial_work();
4837 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4838 }
4839 }
4840
4841 // Start parallel work.
4842 double young_time = 0.0;
4843 bool has_young_time = false;
4844 double non_young_time = 0.0;
4845 bool has_non_young_time = false;
4846
4847 while (true) {
4848 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4849 size_t cur = end - chunk_size();
4850
4851 if (cur >= _num_work_items) {
4852 break;
4853 }
4854
4855 double start_time = os::elapsedTime();
4856
4857 end = MIN2(end, _num_work_items);
4858
4859 for (; cur < end; cur++) {
4860 bool is_young = _work_items[cur].is_young;
4861
4862 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4863
4864 double end_time = os::elapsedTime();
4865 double time_taken = end_time - start_time;
4866 if (is_young) {
4867 young_time += time_taken;
4868 has_young_time = true;
4869 } else {
4870 non_young_time += time_taken;
4871 has_non_young_time = true;
4872 }
4873 start_time = end_time;
4874 }
4875 }
4876
4877 if (has_young_time) {
4878 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4879 }
4880 if (has_non_young_time) {
4881 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4882 }
4883 }
4884 };
4885
4886 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4887 _eden.clear();
4888
4889 double free_cset_start_time = os::elapsedTime();
4890
4891 {
4892 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4893 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4894
4895 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4896
4897 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4898 cl.name(),
4899 num_workers,
4900 _collection_set.region_length());
4901 workers()->run_task(&cl, num_workers);
4902 }
4903 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4904
4905 collection_set->clear();
4906 }
4907
4908 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4909 private:
4910 FreeRegionList* _free_region_list;
4911 HeapRegionSet* _proxy_set;
4912 uint _humongous_regions_removed;
4913 size_t _freed_bytes;
4914 public:
4915
4916 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4917 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4918 }
4919
4920 virtual bool doHeapRegion(HeapRegion* r) {
4921 if (!r->is_starts_humongous()) {
4922 return false;
4923 }
4924
4925 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4926
4927 oop obj = (oop)r->bottom();
4928 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4929
4930 // The following checks whether the humongous object is live are sufficient.
4931 // The main additional check (in addition to having a reference from the roots
4932 // or the young gen) is whether the humongous object has a remembered set entry.
4933 //
4934 // A humongous object cannot be live if there is no remembered set for it
4935 // because:
4936 // - there can be no references from within humongous starts regions referencing
4937 // the object because we never allocate other objects into them.
4938 // (I.e. there are no intra-region references that may be missed by the
4939 // remembered set)
4940 // - as soon there is a remembered set entry to the humongous starts region
4941 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4942 // until the end of a concurrent mark.
4943 //
4944 // It is not required to check whether the object has been found dead by marking
4945 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4946 // all objects allocated during that time are considered live.
4947 // SATB marking is even more conservative than the remembered set.
4948 // So if at this point in the collection there is no remembered set entry,
4949 // nobody has a reference to it.
4950 // At the start of collection we flush all refinement logs, and remembered sets
4951 // are completely up-to-date wrt to references to the humongous object.
4952 //
4953 // Other implementation considerations:
4954 // - never consider object arrays at this time because they would pose
4955 // considerable effort for cleaning up the the remembered sets. This is
4956 // required because stale remembered sets might reference locations that
4957 // are currently allocated into.
4958 uint region_idx = r->hrm_index();
4959 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4960 !r->rem_set()->is_empty()) {
4961 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",
4962 region_idx,
4963 (size_t)obj->size() * HeapWordSize,
4964 p2i(r->bottom()),
4965 r->rem_set()->occupied(),
4966 r->rem_set()->strong_code_roots_list_length(),
4967 next_bitmap->isMarked(r->bottom()),
4968 g1h->is_humongous_reclaim_candidate(region_idx),
4969 obj->is_typeArray()
4970 );
4971 return false;
4972 }
4973
4974 guarantee(obj->is_typeArray(),
4975 "Only eagerly reclaiming type arrays is supported, but the object "
4976 PTR_FORMAT " is not.", p2i(r->bottom()));
4977
4978 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",
4979 region_idx,
4980 (size_t)obj->size() * HeapWordSize,
4981 p2i(r->bottom()),
4982 r->rem_set()->occupied(),
4983 r->rem_set()->strong_code_roots_list_length(),
4984 next_bitmap->isMarked(r->bottom()),
4985 g1h->is_humongous_reclaim_candidate(region_idx),
4986 obj->is_typeArray()
4987 );
4988
4989 // Need to clear mark bit of the humongous object if already set.
4990 if (next_bitmap->isMarked(r->bottom())) {
4991 next_bitmap->clear(r->bottom());
4992 }
4993 do {
4994 HeapRegion* next = g1h->next_region_in_humongous(r);
4995 _freed_bytes += r->used();
4996 r->set_containing_set(NULL);
4997 _humongous_regions_removed++;
4998 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4999 r = next;
5000 } while (r != NULL);
5001
5002 return false;
5003 }
5004
5005 uint humongous_free_count() {
5006 return _humongous_regions_removed;
5007 }
5008
5009 size_t bytes_freed() const {
5010 return _freed_bytes;
5011 }
5012 };
5013
5014 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5015 assert_at_safepoint(true);
5016
5017 if (!G1EagerReclaimHumongousObjects ||
5018 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5019 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5020 return;
5021 }
5022
5023 double start_time = os::elapsedTime();
5024
5025 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5026
5027 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5028 heap_region_iterate(&cl);
5029
5030 remove_from_old_sets(0, cl.humongous_free_count());
5031
5032 G1HRPrinter* hrp = hr_printer();
5033 if (hrp->is_active()) {
5034 FreeRegionListIterator iter(&local_cleanup_list);
5035 while (iter.more_available()) {
5036 HeapRegion* hr = iter.get_next();
5037 hrp->cleanup(hr);
5038 }
5039 }
5040
5041 prepend_to_freelist(&local_cleanup_list);
5042 decrement_summary_bytes(cl.bytes_freed());
5043
5044 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5045 cl.humongous_free_count());
5046 }
5047
5048 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5049 public:
5050 virtual bool doHeapRegion(HeapRegion* r) {
5051 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5052 G1CollectedHeap::heap()->clear_in_cset(r);
5053 r->set_young_index_in_cset(-1);
5054 return false;
5055 }
5056 };
5057
5058 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5059 G1AbandonCollectionSetClosure cl;
5060 collection_set->iterate(&cl);
5061
5062 collection_set->clear();
5063 collection_set->stop_incremental_building();
5064 }
5065
5066 void G1CollectedHeap::set_free_regions_coming() {
5067 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5068
5069 assert(!free_regions_coming(), "pre-condition");
5070 _free_regions_coming = true;
5071 }
5072
5073 void G1CollectedHeap::reset_free_regions_coming() {
5074 assert(free_regions_coming(), "pre-condition");
5075
5076 {
5077 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5078 _free_regions_coming = false;
5079 SecondaryFreeList_lock->notify_all();
5080 }
5081
5082 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5083 }
5084
5085 void G1CollectedHeap::wait_while_free_regions_coming() {
5086 // Most of the time we won't have to wait, so let's do a quick test
5087 // first before we take the lock.
5088 if (!free_regions_coming()) {
5089 return;
5090 }
5091
5092 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5093
5094 {
5095 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5096 while (free_regions_coming()) {
5097 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5098 }
5099 }
5100
5101 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5102 }
5103
5104 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5105 return _allocator->is_retained_old_region(hr);
5106 }
5107
5108 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5109 _eden.add(hr);
5110 _g1_policy->set_region_eden(hr);
5111 }
5112
5113 #ifdef ASSERT
5114
5115 class NoYoungRegionsClosure: public HeapRegionClosure {
5116 private:
5117 bool _success;
5118 public:
5119 NoYoungRegionsClosure() : _success(true) { }
5120 bool doHeapRegion(HeapRegion* r) {
5121 if (r->is_young()) {
5122 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5123 p2i(r->bottom()), p2i(r->end()));
5124 _success = false;
5125 }
5126 return false;
5127 }
5128 bool success() { return _success; }
5129 };
5130
5131 bool G1CollectedHeap::check_young_list_empty() {
5132 bool ret = (young_regions_count() == 0);
5133
5134 NoYoungRegionsClosure closure;
5135 heap_region_iterate(&closure);
5136 ret = ret && closure.success();
5137
5138 return ret;
5139 }
5140
5141 #endif // ASSERT
5142
5143 class TearDownRegionSetsClosure : public HeapRegionClosure {
5144 private:
5145 HeapRegionSet *_old_set;
5146
5147 public:
5148 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5149
5150 bool doHeapRegion(HeapRegion* r) {
5151 if (r->is_old()) {
5152 _old_set->remove(r);
5153 } else if(r->is_young()) {
5154 r->uninstall_surv_rate_group();
5155 } else {
5156 // We ignore free regions, we'll empty the free list afterwards.
5157 // We ignore humongous regions, we're not tearing down the
5158 // humongous regions set.
5159 assert(r->is_free() || r->is_humongous(),
5160 "it cannot be another type");
5161 }
5162 return false;
5163 }
5164
5165 ~TearDownRegionSetsClosure() {
5166 assert(_old_set->is_empty(), "post-condition");
5167 }
5168 };
5169
5170 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5171 assert_at_safepoint(true /* should_be_vm_thread */);
5172
5173 if (!free_list_only) {
5174 TearDownRegionSetsClosure cl(&_old_set);
5175 heap_region_iterate(&cl);
5176
5177 // Note that emptying the _young_list is postponed and instead done as
5178 // the first step when rebuilding the regions sets again. The reason for
5179 // this is that during a full GC string deduplication needs to know if
5180 // a collected region was young or old when the full GC was initiated.
5181 }
5182 _hrm.remove_all_free_regions();
5183 }
5184
5185 void G1CollectedHeap::increase_used(size_t bytes) {
5186 _summary_bytes_used += bytes;
5187 }
5188
5189 void G1CollectedHeap::decrease_used(size_t bytes) {
5190 assert(_summary_bytes_used >= bytes,
5191 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5192 _summary_bytes_used, bytes);
5193 _summary_bytes_used -= bytes;
5194 }
5195
5196 void G1CollectedHeap::set_used(size_t bytes) {
5197 _summary_bytes_used = bytes;
5198 }
5199
5200 class RebuildRegionSetsClosure : public HeapRegionClosure {
5201 private:
5202 bool _free_list_only;
5203 HeapRegionSet* _old_set;
5204 HeapRegionManager* _hrm;
5205 size_t _total_used;
5206
5207 public:
5208 RebuildRegionSetsClosure(bool free_list_only,
5209 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5210 _free_list_only(free_list_only),
5211 _old_set(old_set), _hrm(hrm), _total_used(0) {
5212 assert(_hrm->num_free_regions() == 0, "pre-condition");
5213 if (!free_list_only) {
5214 assert(_old_set->is_empty(), "pre-condition");
5215 }
5216 }
5217
5218 bool doHeapRegion(HeapRegion* r) {
5219 if (r->is_empty()) {
5220 // Add free regions to the free list
5221 r->set_free();
5222 r->set_allocation_context(AllocationContext::system());
5223 _hrm->insert_into_free_list(r);
5224 } else if (!_free_list_only) {
5225
5226 if (r->is_humongous()) {
5227 // We ignore humongous regions. We left the humongous set unchanged.
5228 } else {
5229 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5230 // We now consider all regions old, so register as such. Leave
5231 // archive regions set that way, however, while still adding
5232 // them to the old set.
5233 if (!r->is_archive()) {
5234 r->set_old();
5235 }
5236 _old_set->add(r);
5237 }
5238 _total_used += r->used();
5239 }
5240
5241 return false;
5242 }
5243
5244 size_t total_used() {
5245 return _total_used;
5246 }
5247 };
5248
5249 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5250 assert_at_safepoint(true /* should_be_vm_thread */);
5251
5252 if (!free_list_only) {
5253 _eden.clear();
5254 _survivor.clear();
5255 }
5256
5257 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5258 heap_region_iterate(&cl);
5259
5260 if (!free_list_only) {
5261 set_used(cl.total_used());
5262 if (_archive_allocator != NULL) {
5263 _archive_allocator->clear_used();
5264 }
5265 }
5266 assert(used_unlocked() == recalculate_used(),
5267 "inconsistent used_unlocked(), "
5268 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5269 used_unlocked(), recalculate_used());
5270 }
5271
5272 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5273 _refine_cte_cl->set_concurrent(concurrent);
5274 }
5275
5276 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5277 HeapRegion* hr = heap_region_containing(p);
5278 return hr->is_in(p);
5279 }
5280
5281 // Methods for the mutator alloc region
5282
5283 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5284 bool force) {
5285 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5286 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5287 if (force || should_allocate) {
5288 HeapRegion* new_alloc_region = new_region(word_size,
5289 false /* is_old */,
5290 false /* do_expand */);
5291 if (new_alloc_region != NULL) {
5292 set_region_short_lived_locked(new_alloc_region);
5293 _hr_printer.alloc(new_alloc_region, !should_allocate);
5294 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5295 return new_alloc_region;
5296 }
5297 }
5298 return NULL;
5299 }
5300
5301 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5302 size_t allocated_bytes) {
5303 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5304 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5305
5306 collection_set()->add_eden_region(alloc_region);
5307 increase_used(allocated_bytes);
5308 _hr_printer.retire(alloc_region);
5309 // We update the eden sizes here, when the region is retired,
5310 // instead of when it's allocated, since this is the point that its
5311 // used space has been recored in _summary_bytes_used.
5312 g1mm()->update_eden_size();
5313 }
5314
5315 // Methods for the GC alloc regions
5316
5317 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5318 if (dest.is_old()) {
5319 return true;
5320 } else {
5321 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5322 }
5323 }
5324
5325 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5326 assert(FreeList_lock->owned_by_self(), "pre-condition");
5327
5328 if (!has_more_regions(dest)) {
5329 return NULL;
5330 }
5331
5332 const bool is_survivor = dest.is_young();
5333
5334 HeapRegion* new_alloc_region = new_region(word_size,
5335 !is_survivor,
5336 true /* do_expand */);
5337 if (new_alloc_region != NULL) {
5338 // We really only need to do this for old regions given that we
5339 // should never scan survivors. But it doesn't hurt to do it
5340 // for survivors too.
5341 new_alloc_region->record_timestamp();
5342 if (is_survivor) {
5343 new_alloc_region->set_survivor();
5344 _survivor.add(new_alloc_region);
5345 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5346 } else {
5347 new_alloc_region->set_old();
5348 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5349 }
5350 _hr_printer.alloc(new_alloc_region);
5351 bool during_im = collector_state()->during_initial_mark_pause();
5352 new_alloc_region->note_start_of_copying(during_im);
5353 return new_alloc_region;
5354 }
5355 return NULL;
5356 }
5357
5358 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5359 size_t allocated_bytes,
5360 InCSetState dest) {
5361 bool during_im = collector_state()->during_initial_mark_pause();
5362 alloc_region->note_end_of_copying(during_im);
5363 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5364 if (dest.is_old()) {
5365 _old_set.add(alloc_region);
5366 }
5367 _hr_printer.retire(alloc_region);
5368 }
5369
5370 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5371 bool expanded = false;
5372 uint index = _hrm.find_highest_free(&expanded);
5373
5374 if (index != G1_NO_HRM_INDEX) {
5375 if (expanded) {
5376 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5377 HeapRegion::GrainWords * HeapWordSize);
5378 }
5379 _hrm.allocate_free_regions_starting_at(index, 1);
5380 return region_at(index);
5381 }
5382 return NULL;
5383 }
5384
5385 // Optimized nmethod scanning
5386
5387 class RegisterNMethodOopClosure: public OopClosure {
5388 G1CollectedHeap* _g1h;
5389 nmethod* _nm;
5390
5391 template <class T> void do_oop_work(T* p) {
5392 T heap_oop = oopDesc::load_heap_oop(p);
5393 if (!oopDesc::is_null(heap_oop)) {
5394 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5395 HeapRegion* hr = _g1h->heap_region_containing(obj);
5396 assert(!hr->is_continues_humongous(),
5397 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5398 " starting at " HR_FORMAT,
5399 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5400
5401 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5402 hr->add_strong_code_root_locked(_nm);
5403 }
5404 }
5405
5406 public:
5407 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5408 _g1h(g1h), _nm(nm) {}
5409
5410 void do_oop(oop* p) { do_oop_work(p); }
5411 void do_oop(narrowOop* p) { do_oop_work(p); }
5412 };
5413
5414 class UnregisterNMethodOopClosure: public OopClosure {
5415 G1CollectedHeap* _g1h;
5416 nmethod* _nm;
5417
5418 template <class T> void do_oop_work(T* p) {
5419 T heap_oop = oopDesc::load_heap_oop(p);
5420 if (!oopDesc::is_null(heap_oop)) {
5421 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5422 HeapRegion* hr = _g1h->heap_region_containing(obj);
5423 assert(!hr->is_continues_humongous(),
5424 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5425 " starting at " HR_FORMAT,
5426 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5427
5428 hr->remove_strong_code_root(_nm);
5429 }
5430 }
5431
5432 public:
5433 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5434 _g1h(g1h), _nm(nm) {}
5435
5436 void do_oop(oop* p) { do_oop_work(p); }
5437 void do_oop(narrowOop* p) { do_oop_work(p); }
5438 };
5439
5440 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5441 CollectedHeap::register_nmethod(nm);
5442
5443 guarantee(nm != NULL, "sanity");
5444 RegisterNMethodOopClosure reg_cl(this, nm);
5445 nm->oops_do(®_cl);
5446 }
5447
5448 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5449 CollectedHeap::unregister_nmethod(nm);
5450
5451 guarantee(nm != NULL, "sanity");
5452 UnregisterNMethodOopClosure reg_cl(this, nm);
5453 nm->oops_do(®_cl, true);
5454 }
5455
5456 void G1CollectedHeap::purge_code_root_memory() {
5457 double purge_start = os::elapsedTime();
5458 G1CodeRootSet::purge();
5459 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5460 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5461 }
5462
5463 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5464 G1CollectedHeap* _g1h;
5465
5466 public:
5467 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5468 _g1h(g1h) {}
5469
5470 void do_code_blob(CodeBlob* cb) {
5471 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5472 if (nm == NULL) {
5473 return;
5474 }
5475
5476 if (ScavengeRootsInCode) {
5477 _g1h->register_nmethod(nm);
5478 }
5479 }
5480 };
5481
5482 void G1CollectedHeap::rebuild_strong_code_roots() {
5483 RebuildStrongCodeRootClosure blob_cl(this);
5484 CodeCache::blobs_do(&blob_cl);
5485 }