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 RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1113 G1CollectedHeap* _g1h;
1114 UpdateRSOopClosure _cl;
1115 public:
1116 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1117 _cl(g1->g1_rem_set(), worker_i),
1118 _g1h(g1)
1119 { }
1120
1121 bool doHeapRegion(HeapRegion* r) {
1122 if (!r->is_continues_humongous()) {
1123 _cl.set_from(r);
1124 r->oop_iterate(&_cl);
1125 }
1126 return false;
1127 }
1128 };
1129
1130 class ParRebuildRSTask: public AbstractGangTask {
1131 G1CollectedHeap* _g1;
1132 HeapRegionClaimer _hrclaimer;
1133
1134 public:
1135 ParRebuildRSTask(G1CollectedHeap* g1) :
1136 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1137
1138 void work(uint worker_id) {
1139 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1140 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1141 }
1142 };
1143
1144 class PostCompactionPrinterClosure: public HeapRegionClosure {
1145 private:
1146 G1HRPrinter* _hr_printer;
1147 public:
1148 bool doHeapRegion(HeapRegion* hr) {
1149 assert(!hr->is_young(), "not expecting to find young regions");
1150 _hr_printer->post_compaction(hr);
1151 return false;
1152 }
1153
1154 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1155 : _hr_printer(hr_printer) { }
1156 };
1157
1158 void G1CollectedHeap::print_hrm_post_compaction() {
1159 if (_hr_printer.is_active()) {
1160 PostCompactionPrinterClosure cl(hr_printer());
1161 heap_region_iterate(&cl);
1162 }
1163
1164 }
1165
1166 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1167 bool clear_all_soft_refs) {
1168 assert_at_safepoint(true /* should_be_vm_thread */);
1169
1170 if (GCLocker::check_active_before_gc()) {
1171 return false;
1172 }
1173
1174 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1175 gc_timer->register_gc_start();
1176
1177 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1178 GCIdMark gc_id_mark;
1179 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1180
1181 SvcGCMarker sgcm(SvcGCMarker::FULL);
1182 ResourceMark rm;
1183
1184 print_heap_before_gc();
1185 print_heap_regions();
1186 trace_heap_before_gc(gc_tracer);
1187
1188 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1189
1190 _verifier->verify_region_sets_optional();
1191
1192 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1193 collector_policy()->should_clear_all_soft_refs();
1194
1195 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1196
1197 {
1198 IsGCActiveMark x;
1199
1200 // Timing
1201 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1202 GCTraceCPUTime tcpu;
1203
1204 {
1205 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1206 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1207 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1208
1209 G1HeapTransition heap_transition(this);
1210 g1_policy()->record_full_collection_start();
1211
1212 // Note: When we have a more flexible GC logging framework that
1213 // allows us to add optional attributes to a GC log record we
1214 // could consider timing and reporting how long we wait in the
1215 // following two methods.
1216 wait_while_free_regions_coming();
1217 // If we start the compaction before the CM threads finish
1218 // scanning the root regions we might trip them over as we'll
1219 // be moving objects / updating references. So let's wait until
1220 // they are done. By telling them to abort, they should complete
1221 // early.
1222 _cm->root_regions()->abort();
1223 _cm->root_regions()->wait_until_scan_finished();
1224 append_secondary_free_list_if_not_empty_with_lock();
1225
1226 gc_prologue(true);
1227 increment_total_collections(true /* full gc */);
1228 increment_old_marking_cycles_started();
1229
1230 assert(used() == recalculate_used(), "Should be equal");
1231
1232 _verifier->verify_before_gc();
1233
1234 _verifier->check_bitmaps("Full GC Start");
1235 pre_full_gc_dump(gc_timer);
1236
1237 #if defined(COMPILER2) || INCLUDE_JVMCI
1238 DerivedPointerTable::clear();
1239 #endif
1240
1241 // Disable discovery and empty the discovered lists
1242 // for the CM ref processor.
1243 ref_processor_cm()->disable_discovery();
1244 ref_processor_cm()->abandon_partial_discovery();
1245 ref_processor_cm()->verify_no_references_recorded();
1246
1247 // Abandon current iterations of concurrent marking and concurrent
1248 // refinement, if any are in progress.
1249 concurrent_mark()->abort();
1250
1251 // Make sure we'll choose a new allocation region afterwards.
1252 _allocator->release_mutator_alloc_region();
1253 _allocator->abandon_gc_alloc_regions();
1254 g1_rem_set()->cleanupHRRS();
1255
1256 // We may have added regions to the current incremental collection
1257 // set between the last GC or pause and now. We need to clear the
1258 // incremental collection set and then start rebuilding it afresh
1259 // after this full GC.
1260 abandon_collection_set(collection_set());
1261
1262 tear_down_region_sets(false /* free_list_only */);
1263 collector_state()->set_gcs_are_young(true);
1264
1265 // See the comments in g1CollectedHeap.hpp and
1266 // G1CollectedHeap::ref_processing_init() about
1267 // how reference processing currently works in G1.
1268
1269 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1270 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1271
1272 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1273 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1274
1275 ref_processor_stw()->enable_discovery();
1276 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1277
1278 // Do collection work
1279 {
1280 HandleMark hm; // Discard invalid handles created during gc
1281 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1282 }
1283
1284 assert(num_free_regions() == 0, "we should not have added any free regions");
1285 rebuild_region_sets(false /* free_list_only */);
1286
1287 // Enqueue any discovered reference objects that have
1288 // not been removed from the discovered lists.
1289 ref_processor_stw()->enqueue_discovered_references();
1290
1291 #if defined(COMPILER2) || INCLUDE_JVMCI
1292 DerivedPointerTable::update_pointers();
1293 #endif
1294
1295 MemoryService::track_memory_usage();
1296
1297 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1298 ref_processor_stw()->verify_no_references_recorded();
1299
1300 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1301 ClassLoaderDataGraph::purge();
1302 MetaspaceAux::verify_metrics();
1303
1304 // Note: since we've just done a full GC, concurrent
1305 // marking is no longer active. Therefore we need not
1306 // re-enable reference discovery for the CM ref processor.
1307 // That will be done at the start of the next marking cycle.
1308 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1309 ref_processor_cm()->verify_no_references_recorded();
1310
1311 reset_gc_time_stamp();
1312 // Since everything potentially moved, we will clear all remembered
1313 // sets, and clear all cards. Later we will rebuild remembered
1314 // sets. We will also reset the GC time stamps of the regions.
1315 clear_rsets_post_compaction();
1316 check_gc_time_stamps();
1317
1318 resize_if_necessary_after_full_collection();
1319
1320 // We should do this after we potentially resize the heap so
1321 // that all the COMMIT / UNCOMMIT events are generated before
1322 // the compaction events.
1323 print_hrm_post_compaction();
1324
1325 if (_hot_card_cache->use_cache()) {
1326 _hot_card_cache->reset_card_counts();
1327 _hot_card_cache->reset_hot_cache();
1328 }
1329
1330 // Rebuild remembered sets of all regions.
1331 uint n_workers =
1332 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1333 workers()->active_workers(),
1334 Threads::number_of_non_daemon_threads());
1335 workers()->update_active_workers(n_workers);
1336 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1337
1338 ParRebuildRSTask rebuild_rs_task(this);
1339 workers()->run_task(&rebuild_rs_task);
1340
1341 // Rebuild the strong code root lists for each region
1342 rebuild_strong_code_roots();
1343
1344 if (true) { // FIXME
1345 MetaspaceGC::compute_new_size();
1346 }
1347
1348 #ifdef TRACESPINNING
1349 ParallelTaskTerminator::print_termination_counts();
1350 #endif
1351
1352 // Discard all rset updates
1353 JavaThread::dirty_card_queue_set().abandon_logs();
1354 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1355
1356 // At this point there should be no regions in the
1357 // entire heap tagged as young.
1358 assert(check_young_list_empty(), "young list should be empty at this point");
1359
1360 // Update the number of full collections that have been completed.
1361 increment_old_marking_cycles_completed(false /* concurrent */);
1362
1363 _hrm.verify_optional();
1364 _verifier->verify_region_sets_optional();
1365
1366 _verifier->verify_after_gc();
1367
1368 // Clear the previous marking bitmap, if needed for bitmap verification.
1369 // Note we cannot do this when we clear the next marking bitmap in
1370 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1371 // objects marked during a full GC against the previous bitmap.
1372 // But we need to clear it before calling check_bitmaps below since
1373 // the full GC has compacted objects and updated TAMS but not updated
1374 // the prev bitmap.
1375 if (G1VerifyBitmaps) {
1376 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1377 _cm->clear_prev_bitmap(workers());
1378 }
1379 _verifier->check_bitmaps("Full GC End");
1380
1381 start_new_collection_set();
1382
1383 _allocator->init_mutator_alloc_region();
1384
1385 g1_policy()->record_full_collection_end();
1386
1387 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1388 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1389 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1390 // before any GC notifications are raised.
1391 g1mm()->update_sizes();
1392
1393 gc_epilogue(true);
1394
1395 heap_transition.print();
1396
1397 print_heap_after_gc();
1398 print_heap_regions();
1399 trace_heap_after_gc(gc_tracer);
1400
1401 post_full_gc_dump(gc_timer);
1402 }
1403
1404 gc_timer->register_gc_end();
1405 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1406 }
1407
1408 return true;
1409 }
1410
1411 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1412 // Currently, there is no facility in the do_full_collection(bool) API to notify
1413 // the caller that the collection did not succeed (e.g., because it was locked
1414 // out by the GC locker). So, right now, we'll ignore the return value.
1415 bool dummy = do_full_collection(true, /* explicit_gc */
1416 clear_all_soft_refs);
1417 }
1418
1419 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1420 // Include bytes that will be pre-allocated to support collections, as "used".
1421 const size_t used_after_gc = used();
1422 const size_t capacity_after_gc = capacity();
1423 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1424
1425 // This is enforced in arguments.cpp.
1426 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1427 "otherwise the code below doesn't make sense");
1428
1429 // We don't have floating point command-line arguments
1430 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1431 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1432 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1433 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1434
1435 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1436 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1437
1438 // We have to be careful here as these two calculations can overflow
1439 // 32-bit size_t's.
1440 double used_after_gc_d = (double) used_after_gc;
1441 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1442 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1443
1444 // Let's make sure that they are both under the max heap size, which
1445 // by default will make them fit into a size_t.
1446 double desired_capacity_upper_bound = (double) max_heap_size;
1447 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1448 desired_capacity_upper_bound);
1449 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1450 desired_capacity_upper_bound);
1451
1452 // We can now safely turn them into size_t's.
1453 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1454 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1455
1456 // This assert only makes sense here, before we adjust them
1457 // with respect to the min and max heap size.
1458 assert(minimum_desired_capacity <= maximum_desired_capacity,
1459 "minimum_desired_capacity = " SIZE_FORMAT ", "
1460 "maximum_desired_capacity = " SIZE_FORMAT,
1461 minimum_desired_capacity, maximum_desired_capacity);
1462
1463 // Should not be greater than the heap max size. No need to adjust
1464 // it with respect to the heap min size as it's a lower bound (i.e.,
1465 // we'll try to make the capacity larger than it, not smaller).
1466 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1467 // Should not be less than the heap min size. No need to adjust it
1468 // with respect to the heap max size as it's an upper bound (i.e.,
1469 // we'll try to make the capacity smaller than it, not greater).
1470 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1471
1472 if (capacity_after_gc < minimum_desired_capacity) {
1473 // Don't expand unless it's significant
1474 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1475
1476 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1477 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1478 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1479
1480 expand(expand_bytes, _workers);
1481
1482 // No expansion, now see if we want to shrink
1483 } else if (capacity_after_gc > maximum_desired_capacity) {
1484 // Capacity too large, compute shrinking size
1485 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1486
1487 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1488 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1489 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1490
1491 shrink(shrink_bytes);
1492 }
1493 }
1494
1495 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1496 AllocationContext_t context,
1497 bool do_gc,
1498 bool clear_all_soft_refs,
1499 bool expect_null_mutator_alloc_region,
1500 bool* gc_succeeded) {
1501 *gc_succeeded = true;
1502 // Let's attempt the allocation first.
1503 HeapWord* result =
1504 attempt_allocation_at_safepoint(word_size,
1505 context,
1506 expect_null_mutator_alloc_region);
1507 if (result != NULL) {
1508 assert(*gc_succeeded, "sanity");
1509 return result;
1510 }
1511
1512 // In a G1 heap, we're supposed to keep allocation from failing by
1513 // incremental pauses. Therefore, at least for now, we'll favor
1514 // expansion over collection. (This might change in the future if we can
1515 // do something smarter than full collection to satisfy a failed alloc.)
1516 result = expand_and_allocate(word_size, context);
1517 if (result != NULL) {
1518 assert(*gc_succeeded, "sanity");
1519 return result;
1520 }
1521
1522 if (do_gc) {
1523 // Expansion didn't work, we'll try to do a Full GC.
1524 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1525 clear_all_soft_refs);
1526 }
1527
1528 return NULL;
1529 }
1530
1531 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1532 AllocationContext_t context,
1533 bool* succeeded) {
1534 assert_at_safepoint(true /* should_be_vm_thread */);
1535
1536 // Attempts to allocate followed by Full GC.
1537 HeapWord* result =
1538 satisfy_failed_allocation_helper(word_size,
1539 context,
1540 true, /* do_gc */
1541 false, /* clear_all_soft_refs */
1542 false, /* expect_null_mutator_alloc_region */
1543 succeeded);
1544
1545 if (result != NULL || !*succeeded) {
1546 return result;
1547 }
1548
1549 // Attempts to allocate followed by Full GC that will collect all soft references.
1550 result = satisfy_failed_allocation_helper(word_size,
1551 context,
1552 true, /* do_gc */
1553 true, /* clear_all_soft_refs */
1554 true, /* expect_null_mutator_alloc_region */
1555 succeeded);
1556
1557 if (result != NULL || !*succeeded) {
1558 return result;
1559 }
1560
1561 // Attempts to allocate, no GC
1562 result = satisfy_failed_allocation_helper(word_size,
1563 context,
1564 false, /* do_gc */
1565 false, /* clear_all_soft_refs */
1566 true, /* expect_null_mutator_alloc_region */
1567 succeeded);
1568
1569 if (result != NULL) {
1570 assert(*succeeded, "sanity");
1571 return result;
1572 }
1573
1574 assert(!collector_policy()->should_clear_all_soft_refs(),
1575 "Flag should have been handled and cleared prior to this point");
1576
1577 // What else? We might try synchronous finalization later. If the total
1578 // space available is large enough for the allocation, then a more
1579 // complete compaction phase than we've tried so far might be
1580 // appropriate.
1581 assert(*succeeded, "sanity");
1582 return NULL;
1583 }
1584
1585 // Attempting to expand the heap sufficiently
1586 // to support an allocation of the given "word_size". If
1587 // successful, perform the allocation and return the address of the
1588 // allocated block, or else "NULL".
1589
1590 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1591 assert_at_safepoint(true /* should_be_vm_thread */);
1592
1593 _verifier->verify_region_sets_optional();
1594
1595 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1596 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1597 word_size * HeapWordSize);
1598
1599
1600 if (expand(expand_bytes, _workers)) {
1601 _hrm.verify_optional();
1602 _verifier->verify_region_sets_optional();
1603 return attempt_allocation_at_safepoint(word_size,
1604 context,
1605 false /* expect_null_mutator_alloc_region */);
1606 }
1607 return NULL;
1608 }
1609
1610 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1611 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1612 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1613 HeapRegion::GrainBytes);
1614
1615 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1616 expand_bytes, aligned_expand_bytes);
1617
1618 if (is_maximal_no_gc()) {
1619 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1620 return false;
1621 }
1622
1623 double expand_heap_start_time_sec = os::elapsedTime();
1624 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1625 assert(regions_to_expand > 0, "Must expand by at least one region");
1626
1627 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1628 if (expand_time_ms != NULL) {
1629 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1630 }
1631
1632 if (expanded_by > 0) {
1633 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1634 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1635 g1_policy()->record_new_heap_size(num_regions());
1636 } else {
1637 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1638
1639 // The expansion of the virtual storage space was unsuccessful.
1640 // Let's see if it was because we ran out of swap.
1641 if (G1ExitOnExpansionFailure &&
1642 _hrm.available() >= regions_to_expand) {
1643 // We had head room...
1644 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1645 }
1646 }
1647 return regions_to_expand > 0;
1648 }
1649
1650 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1651 size_t aligned_shrink_bytes =
1652 ReservedSpace::page_align_size_down(shrink_bytes);
1653 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1654 HeapRegion::GrainBytes);
1655 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1656
1657 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1658 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1659
1660
1661 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",
1662 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1663 if (num_regions_removed > 0) {
1664 g1_policy()->record_new_heap_size(num_regions());
1665 } else {
1666 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1667 }
1668 }
1669
1670 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1671 _verifier->verify_region_sets_optional();
1672
1673 // We should only reach here at the end of a Full GC which means we
1674 // should not not be holding to any GC alloc regions. The method
1675 // below will make sure of that and do any remaining clean up.
1676 _allocator->abandon_gc_alloc_regions();
1677
1678 // Instead of tearing down / rebuilding the free lists here, we
1679 // could instead use the remove_all_pending() method on free_list to
1680 // remove only the ones that we need to remove.
1681 tear_down_region_sets(true /* free_list_only */);
1682 shrink_helper(shrink_bytes);
1683 rebuild_region_sets(true /* free_list_only */);
1684
1685 _hrm.verify_optional();
1686 _verifier->verify_region_sets_optional();
1687 }
1688
1689 // Public methods.
1690
1691 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1692 CollectedHeap(),
1693 _collector_policy(collector_policy),
1694 _g1_policy(create_g1_policy()),
1695 _collection_set(this, _g1_policy),
1696 _dirty_card_queue_set(false),
1697 _is_alive_closure_cm(this),
1698 _is_alive_closure_stw(this),
1699 _ref_processor_cm(NULL),
1700 _ref_processor_stw(NULL),
1701 _bot(NULL),
1702 _hot_card_cache(NULL),
1703 _g1_rem_set(NULL),
1704 _cg1r(NULL),
1705 _g1mm(NULL),
1706 _refine_cte_cl(NULL),
1707 _preserved_marks_set(true /* in_c_heap */),
1708 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1709 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1710 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1711 _humongous_reclaim_candidates(),
1712 _has_humongous_reclaim_candidates(false),
1713 _archive_allocator(NULL),
1714 _free_regions_coming(false),
1715 _gc_time_stamp(0),
1716 _summary_bytes_used(0),
1717 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1718 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1719 _expand_heap_after_alloc_failure(true),
1720 _old_marking_cycles_started(0),
1721 _old_marking_cycles_completed(0),
1722 _in_cset_fast_test(),
1723 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1724 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1725
1726 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1727 /* are_GC_task_threads */true,
1728 /* are_ConcurrentGC_threads */false);
1729 _workers->initialize_workers();
1730 _verifier = new G1HeapVerifier(this);
1731
1732 _allocator = G1Allocator::create_allocator(this);
1733
1734 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1735
1736 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1737
1738 // Override the default _filler_array_max_size so that no humongous filler
1739 // objects are created.
1740 _filler_array_max_size = _humongous_object_threshold_in_words;
1741
1742 uint n_queues = ParallelGCThreads;
1743 _task_queues = new RefToScanQueueSet(n_queues);
1744
1745 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1746
1747 for (uint i = 0; i < n_queues; i++) {
1748 RefToScanQueue* q = new RefToScanQueue();
1749 q->initialize();
1750 _task_queues->register_queue(i, q);
1751 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1752 }
1753
1754 // Initialize the G1EvacuationFailureALot counters and flags.
1755 NOT_PRODUCT(reset_evacuation_should_fail();)
1756
1757 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1758 }
1759
1760 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1761 size_t size,
1762 size_t translation_factor) {
1763 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1764 // Allocate a new reserved space, preferring to use large pages.
1765 ReservedSpace rs(size, preferred_page_size);
1766 G1RegionToSpaceMapper* result =
1767 G1RegionToSpaceMapper::create_mapper(rs,
1768 size,
1769 rs.alignment(),
1770 HeapRegion::GrainBytes,
1771 translation_factor,
1772 mtGC);
1773
1774 os::trace_page_sizes_for_requested_size(description,
1775 size,
1776 preferred_page_size,
1777 rs.alignment(),
1778 rs.base(),
1779 rs.size());
1780
1781 return result;
1782 }
1783
1784 jint G1CollectedHeap::initialize() {
1785 CollectedHeap::pre_initialize();
1786 os::enable_vtime();
1787
1788 // Necessary to satisfy locking discipline assertions.
1789
1790 MutexLocker x(Heap_lock);
1791
1792 // While there are no constraints in the GC code that HeapWordSize
1793 // be any particular value, there are multiple other areas in the
1794 // system which believe this to be true (e.g. oop->object_size in some
1795 // cases incorrectly returns the size in wordSize units rather than
1796 // HeapWordSize).
1797 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1798
1799 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1800 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1801 size_t heap_alignment = collector_policy()->heap_alignment();
1802
1803 // Ensure that the sizes are properly aligned.
1804 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1805 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1806 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1807
1808 _refine_cte_cl = new RefineCardTableEntryClosure();
1809
1810 jint ecode = JNI_OK;
1811 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1812 if (_cg1r == NULL) {
1813 return ecode;
1814 }
1815
1816 // Reserve the maximum.
1817
1818 // When compressed oops are enabled, the preferred heap base
1819 // is calculated by subtracting the requested size from the
1820 // 32Gb boundary and using the result as the base address for
1821 // heap reservation. If the requested size is not aligned to
1822 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1823 // into the ReservedHeapSpace constructor) then the actual
1824 // base of the reserved heap may end up differing from the
1825 // address that was requested (i.e. the preferred heap base).
1826 // If this happens then we could end up using a non-optimal
1827 // compressed oops mode.
1828
1829 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1830 heap_alignment);
1831
1832 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1833
1834 // Create the barrier set for the entire reserved region.
1835 G1SATBCardTableLoggingModRefBS* bs
1836 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1837 bs->initialize();
1838 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1839 set_barrier_set(bs);
1840
1841 // Create the hot card cache.
1842 _hot_card_cache = new G1HotCardCache(this);
1843
1844 // Also create a G1 rem set.
1845 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1846
1847 // Carve out the G1 part of the heap.
1848 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1849 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1850 G1RegionToSpaceMapper* heap_storage =
1851 G1RegionToSpaceMapper::create_mapper(g1_rs,
1852 g1_rs.size(),
1853 page_size,
1854 HeapRegion::GrainBytes,
1855 1,
1856 mtJavaHeap);
1857 os::trace_page_sizes("Heap",
1858 collector_policy()->min_heap_byte_size(),
1859 max_byte_size,
1860 page_size,
1861 heap_rs.base(),
1862 heap_rs.size());
1863 heap_storage->set_mapping_changed_listener(&_listener);
1864
1865 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1866 G1RegionToSpaceMapper* bot_storage =
1867 create_aux_memory_mapper("Block Offset Table",
1868 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1869 G1BlockOffsetTable::heap_map_factor());
1870
1871 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1872 G1RegionToSpaceMapper* cardtable_storage =
1873 create_aux_memory_mapper("Card Table",
1874 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1875 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1876
1877 G1RegionToSpaceMapper* card_counts_storage =
1878 create_aux_memory_mapper("Card Counts Table",
1879 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1880 G1CardCounts::heap_map_factor());
1881
1882 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1883 G1RegionToSpaceMapper* prev_bitmap_storage =
1884 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1885 G1RegionToSpaceMapper* next_bitmap_storage =
1886 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1887
1888 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1889 g1_barrier_set()->initialize(cardtable_storage);
1890 // Do later initialization work for concurrent refinement.
1891 _hot_card_cache->initialize(card_counts_storage);
1892
1893 // 6843694 - ensure that the maximum region index can fit
1894 // in the remembered set structures.
1895 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1896 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1897
1898 g1_rem_set()->initialize(max_capacity(), max_regions());
1899
1900 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1901 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1902 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1903 "too many cards per region");
1904
1905 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1906
1907 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1908
1909 {
1910 HeapWord* start = _hrm.reserved().start();
1911 HeapWord* end = _hrm.reserved().end();
1912 size_t granularity = HeapRegion::GrainBytes;
1913
1914 _in_cset_fast_test.initialize(start, end, granularity);
1915 _humongous_reclaim_candidates.initialize(start, end, granularity);
1916 }
1917
1918 // Create the G1ConcurrentMark data structure and thread.
1919 // (Must do this late, so that "max_regions" is defined.)
1920 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1921 if (_cm == NULL || !_cm->completed_initialization()) {
1922 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1923 return JNI_ENOMEM;
1924 }
1925 _cmThread = _cm->cmThread();
1926
1927 // Now expand into the initial heap size.
1928 if (!expand(init_byte_size, _workers)) {
1929 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1930 return JNI_ENOMEM;
1931 }
1932
1933 // Perform any initialization actions delegated to the policy.
1934 g1_policy()->init(this, &_collection_set);
1935
1936 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1937 SATB_Q_FL_lock,
1938 G1SATBProcessCompletedThreshold,
1939 Shared_SATB_Q_lock);
1940
1941 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1942 DirtyCardQ_CBL_mon,
1943 DirtyCardQ_FL_lock,
1944 (int)concurrent_g1_refine()->yellow_zone(),
1945 (int)concurrent_g1_refine()->red_zone(),
1946 Shared_DirtyCardQ_lock,
1947 NULL, // fl_owner
1948 true); // init_free_ids
1949
1950 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1951 DirtyCardQ_CBL_mon,
1952 DirtyCardQ_FL_lock,
1953 -1, // never trigger processing
1954 -1, // no limit on length
1955 Shared_DirtyCardQ_lock,
1956 &JavaThread::dirty_card_queue_set());
1957
1958 // Here we allocate the dummy HeapRegion that is required by the
1959 // G1AllocRegion class.
1960 HeapRegion* dummy_region = _hrm.get_dummy_region();
1961
1962 // We'll re-use the same region whether the alloc region will
1963 // require BOT updates or not and, if it doesn't, then a non-young
1964 // region will complain that it cannot support allocations without
1965 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1966 dummy_region->set_eden();
1967 // Make sure it's full.
1968 dummy_region->set_top(dummy_region->end());
1969 G1AllocRegion::setup(this, dummy_region);
1970
1971 _allocator->init_mutator_alloc_region();
1972
1973 // Do create of the monitoring and management support so that
1974 // values in the heap have been properly initialized.
1975 _g1mm = new G1MonitoringSupport(this);
1976
1977 G1StringDedup::initialize();
1978
1979 _preserved_marks_set.init(ParallelGCThreads);
1980
1981 _collection_set.initialize(max_regions());
1982
1983 return JNI_OK;
1984 }
1985
1986 void G1CollectedHeap::stop() {
1987 // Stop all concurrent threads. We do this to make sure these threads
1988 // do not continue to execute and access resources (e.g. logging)
1989 // that are destroyed during shutdown.
1990 _cg1r->stop();
1991 _cmThread->stop();
1992 if (G1StringDedup::is_enabled()) {
1993 G1StringDedup::stop();
1994 }
1995 }
1996
1997 void G1CollectedHeap::post_initialize() {
1998 ref_processing_init();
1999 }
2000
2001 void G1CollectedHeap::ref_processing_init() {
2002 // Reference processing in G1 currently works as follows:
2003 //
2004 // * There are two reference processor instances. One is
2005 // used to record and process discovered references
2006 // during concurrent marking; the other is used to
2007 // record and process references during STW pauses
2008 // (both full and incremental).
2009 // * Both ref processors need to 'span' the entire heap as
2010 // the regions in the collection set may be dotted around.
2011 //
2012 // * For the concurrent marking ref processor:
2013 // * Reference discovery is enabled at initial marking.
2014 // * Reference discovery is disabled and the discovered
2015 // references processed etc during remarking.
2016 // * Reference discovery is MT (see below).
2017 // * Reference discovery requires a barrier (see below).
2018 // * Reference processing may or may not be MT
2019 // (depending on the value of ParallelRefProcEnabled
2020 // and ParallelGCThreads).
2021 // * A full GC disables reference discovery by the CM
2022 // ref processor and abandons any entries on it's
2023 // discovered lists.
2024 //
2025 // * For the STW processor:
2026 // * Non MT discovery is enabled at the start of a full GC.
2027 // * Processing and enqueueing during a full GC is non-MT.
2028 // * During a full GC, references are processed after marking.
2029 //
2030 // * Discovery (may or may not be MT) is enabled at the start
2031 // of an incremental evacuation pause.
2032 // * References are processed near the end of a STW evacuation pause.
2033 // * For both types of GC:
2034 // * Discovery is atomic - i.e. not concurrent.
2035 // * Reference discovery will not need a barrier.
2036
2037 MemRegion mr = reserved_region();
2038
2039 // Concurrent Mark ref processor
2040 _ref_processor_cm =
2041 new ReferenceProcessor(mr, // span
2042 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2043 // mt processing
2044 ParallelGCThreads,
2045 // degree of mt processing
2046 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2047 // mt discovery
2048 MAX2(ParallelGCThreads, ConcGCThreads),
2049 // degree of mt discovery
2050 false,
2051 // Reference discovery is not atomic
2052 &_is_alive_closure_cm);
2053 // is alive closure
2054 // (for efficiency/performance)
2055
2056 // STW ref processor
2057 _ref_processor_stw =
2058 new ReferenceProcessor(mr, // span
2059 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2060 // mt processing
2061 ParallelGCThreads,
2062 // degree of mt processing
2063 (ParallelGCThreads > 1),
2064 // mt discovery
2065 ParallelGCThreads,
2066 // degree of mt discovery
2067 true,
2068 // Reference discovery is atomic
2069 &_is_alive_closure_stw);
2070 // is alive closure
2071 // (for efficiency/performance)
2072 }
2073
2074 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2075 return _collector_policy;
2076 }
2077
2078 size_t G1CollectedHeap::capacity() const {
2079 return _hrm.length() * HeapRegion::GrainBytes;
2080 }
2081
2082 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2083 hr->reset_gc_time_stamp();
2084 }
2085
2086 #ifndef PRODUCT
2087
2088 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2089 private:
2090 unsigned _gc_time_stamp;
2091 bool _failures;
2092
2093 public:
2094 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2095 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2096
2097 virtual bool doHeapRegion(HeapRegion* hr) {
2098 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2099 if (_gc_time_stamp != region_gc_time_stamp) {
2100 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2101 region_gc_time_stamp, _gc_time_stamp);
2102 _failures = true;
2103 }
2104 return false;
2105 }
2106
2107 bool failures() { return _failures; }
2108 };
2109
2110 void G1CollectedHeap::check_gc_time_stamps() {
2111 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2112 heap_region_iterate(&cl);
2113 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2114 }
2115 #endif // PRODUCT
2116
2117 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2118 _hot_card_cache->drain(cl, worker_i);
2119 }
2120
2121 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2122 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2123 size_t n_completed_buffers = 0;
2124 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2125 n_completed_buffers++;
2126 }
2127 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2128 dcqs.clear_n_completed_buffers();
2129 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2130 }
2131
2132 // Computes the sum of the storage used by the various regions.
2133 size_t G1CollectedHeap::used() const {
2134 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2135 if (_archive_allocator != NULL) {
2136 result += _archive_allocator->used();
2137 }
2138 return result;
2139 }
2140
2141 size_t G1CollectedHeap::used_unlocked() const {
2142 return _summary_bytes_used;
2143 }
2144
2145 class SumUsedClosure: public HeapRegionClosure {
2146 size_t _used;
2147 public:
2148 SumUsedClosure() : _used(0) {}
2149 bool doHeapRegion(HeapRegion* r) {
2150 _used += r->used();
2151 return false;
2152 }
2153 size_t result() { return _used; }
2154 };
2155
2156 size_t G1CollectedHeap::recalculate_used() const {
2157 double recalculate_used_start = os::elapsedTime();
2158
2159 SumUsedClosure blk;
2160 heap_region_iterate(&blk);
2161
2162 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2163 return blk.result();
2164 }
2165
2166 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2167 switch (cause) {
2168 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2169 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2170 case GCCause::_update_allocation_context_stats_inc: return true;
2171 case GCCause::_wb_conc_mark: return true;
2172 default : return false;
2173 }
2174 }
2175
2176 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2177 switch (cause) {
2178 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2179 case GCCause::_g1_humongous_allocation: return true;
2180 default: return is_user_requested_concurrent_full_gc(cause);
2181 }
2182 }
2183
2184 #ifndef PRODUCT
2185 void G1CollectedHeap::allocate_dummy_regions() {
2186 // Let's fill up most of the region
2187 size_t word_size = HeapRegion::GrainWords - 1024;
2188 // And as a result the region we'll allocate will be humongous.
2189 guarantee(is_humongous(word_size), "sanity");
2190
2191 // _filler_array_max_size is set to humongous object threshold
2192 // but temporarily change it to use CollectedHeap::fill_with_object().
2193 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2194
2195 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2196 // Let's use the existing mechanism for the allocation
2197 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2198 AllocationContext::system());
2199 if (dummy_obj != NULL) {
2200 MemRegion mr(dummy_obj, word_size);
2201 CollectedHeap::fill_with_object(mr);
2202 } else {
2203 // If we can't allocate once, we probably cannot allocate
2204 // again. Let's get out of the loop.
2205 break;
2206 }
2207 }
2208 }
2209 #endif // !PRODUCT
2210
2211 void G1CollectedHeap::increment_old_marking_cycles_started() {
2212 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2213 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2214 "Wrong marking cycle count (started: %d, completed: %d)",
2215 _old_marking_cycles_started, _old_marking_cycles_completed);
2216
2217 _old_marking_cycles_started++;
2218 }
2219
2220 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2221 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2222
2223 // We assume that if concurrent == true, then the caller is a
2224 // concurrent thread that was joined the Suspendible Thread
2225 // Set. If there's ever a cheap way to check this, we should add an
2226 // assert here.
2227
2228 // Given that this method is called at the end of a Full GC or of a
2229 // concurrent cycle, and those can be nested (i.e., a Full GC can
2230 // interrupt a concurrent cycle), the number of full collections
2231 // completed should be either one (in the case where there was no
2232 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2233 // behind the number of full collections started.
2234
2235 // This is the case for the inner caller, i.e. a Full GC.
2236 assert(concurrent ||
2237 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2238 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2239 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2240 "is inconsistent with _old_marking_cycles_completed = %u",
2241 _old_marking_cycles_started, _old_marking_cycles_completed);
2242
2243 // This is the case for the outer caller, i.e. the concurrent cycle.
2244 assert(!concurrent ||
2245 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2246 "for outer caller (concurrent cycle): "
2247 "_old_marking_cycles_started = %u "
2248 "is inconsistent with _old_marking_cycles_completed = %u",
2249 _old_marking_cycles_started, _old_marking_cycles_completed);
2250
2251 _old_marking_cycles_completed += 1;
2252
2253 // We need to clear the "in_progress" flag in the CM thread before
2254 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2255 // is set) so that if a waiter requests another System.gc() it doesn't
2256 // incorrectly see that a marking cycle is still in progress.
2257 if (concurrent) {
2258 _cmThread->set_idle();
2259 }
2260
2261 // This notify_all() will ensure that a thread that called
2262 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2263 // and it's waiting for a full GC to finish will be woken up. It is
2264 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2265 FullGCCount_lock->notify_all();
2266 }
2267
2268 void G1CollectedHeap::collect(GCCause::Cause cause) {
2269 assert_heap_not_locked();
2270
2271 uint gc_count_before;
2272 uint old_marking_count_before;
2273 uint full_gc_count_before;
2274 bool retry_gc;
2275
2276 do {
2277 retry_gc = false;
2278
2279 {
2280 MutexLocker ml(Heap_lock);
2281
2282 // Read the GC count while holding the Heap_lock
2283 gc_count_before = total_collections();
2284 full_gc_count_before = total_full_collections();
2285 old_marking_count_before = _old_marking_cycles_started;
2286 }
2287
2288 if (should_do_concurrent_full_gc(cause)) {
2289 // Schedule an initial-mark evacuation pause that will start a
2290 // concurrent cycle. We're setting word_size to 0 which means that
2291 // we are not requesting a post-GC allocation.
2292 VM_G1IncCollectionPause op(gc_count_before,
2293 0, /* word_size */
2294 true, /* should_initiate_conc_mark */
2295 g1_policy()->max_pause_time_ms(),
2296 cause);
2297 op.set_allocation_context(AllocationContext::current());
2298
2299 VMThread::execute(&op);
2300 if (!op.pause_succeeded()) {
2301 if (old_marking_count_before == _old_marking_cycles_started) {
2302 retry_gc = op.should_retry_gc();
2303 } else {
2304 // A Full GC happened while we were trying to schedule the
2305 // initial-mark GC. No point in starting a new cycle given
2306 // that the whole heap was collected anyway.
2307 }
2308
2309 if (retry_gc) {
2310 if (GCLocker::is_active_and_needs_gc()) {
2311 GCLocker::stall_until_clear();
2312 }
2313 }
2314 }
2315 } else {
2316 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2317 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2318
2319 // Schedule a standard evacuation pause. We're setting word_size
2320 // to 0 which means that we are not requesting a post-GC allocation.
2321 VM_G1IncCollectionPause op(gc_count_before,
2322 0, /* word_size */
2323 false, /* should_initiate_conc_mark */
2324 g1_policy()->max_pause_time_ms(),
2325 cause);
2326 VMThread::execute(&op);
2327 } else {
2328 // Schedule a Full GC.
2329 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2330 VMThread::execute(&op);
2331 }
2332 }
2333 } while (retry_gc);
2334 }
2335
2336 bool G1CollectedHeap::is_in(const void* p) const {
2337 if (_hrm.reserved().contains(p)) {
2338 // Given that we know that p is in the reserved space,
2339 // heap_region_containing() should successfully
2340 // return the containing region.
2341 HeapRegion* hr = heap_region_containing(p);
2342 return hr->is_in(p);
2343 } else {
2344 return false;
2345 }
2346 }
2347
2348 #ifdef ASSERT
2349 bool G1CollectedHeap::is_in_exact(const void* p) const {
2350 bool contains = reserved_region().contains(p);
2351 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2352 if (contains && available) {
2353 return true;
2354 } else {
2355 return false;
2356 }
2357 }
2358 #endif
2359
2360 // Iteration functions.
2361
2362 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2363
2364 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2365 ExtendedOopClosure* _cl;
2366 public:
2367 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2368 bool doHeapRegion(HeapRegion* r) {
2369 if (!r->is_continues_humongous()) {
2370 r->oop_iterate(_cl);
2371 }
2372 return false;
2373 }
2374 };
2375
2376 // Iterates an ObjectClosure over all objects within a HeapRegion.
2377
2378 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2379 ObjectClosure* _cl;
2380 public:
2381 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2382 bool doHeapRegion(HeapRegion* r) {
2383 if (!r->is_continues_humongous()) {
2384 r->object_iterate(_cl);
2385 }
2386 return false;
2387 }
2388 };
2389
2390 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2391 IterateObjectClosureRegionClosure blk(cl);
2392 heap_region_iterate(&blk);
2393 }
2394
2395 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2396 _hrm.iterate(cl);
2397 }
2398
2399 void
2400 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2401 uint worker_id,
2402 HeapRegionClaimer *hrclaimer,
2403 bool concurrent) const {
2404 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2405 }
2406
2407 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2408 _collection_set.iterate(cl);
2409 }
2410
2411 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2412 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2413 }
2414
2415 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2416 HeapRegion* result = _hrm.next_region_in_heap(from);
2417 while (result != NULL && result->is_pinned()) {
2418 result = _hrm.next_region_in_heap(result);
2419 }
2420 return result;
2421 }
2422
2423 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2424 HeapRegion* hr = heap_region_containing(addr);
2425 return hr->block_start(addr);
2426 }
2427
2428 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2429 HeapRegion* hr = heap_region_containing(addr);
2430 return hr->block_size(addr);
2431 }
2432
2433 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2434 HeapRegion* hr = heap_region_containing(addr);
2435 return hr->block_is_obj(addr);
2436 }
2437
2438 bool G1CollectedHeap::supports_tlab_allocation() const {
2439 return true;
2440 }
2441
2442 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2443 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2444 }
2445
2446 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2447 return _eden.length() * HeapRegion::GrainBytes;
2448 }
2449
2450 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2451 // must be equal to the humongous object limit.
2452 size_t G1CollectedHeap::max_tlab_size() const {
2453 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2454 }
2455
2456 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2457 AllocationContext_t context = AllocationContext::current();
2458 return _allocator->unsafe_max_tlab_alloc(context);
2459 }
2460
2461 size_t G1CollectedHeap::max_capacity() const {
2462 return _hrm.reserved().byte_size();
2463 }
2464
2465 jlong G1CollectedHeap::millis_since_last_gc() {
2466 // See the notes in GenCollectedHeap::millis_since_last_gc()
2467 // for more information about the implementation.
2468 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2469 _g1_policy->collection_pause_end_millis();
2470 if (ret_val < 0) {
2471 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2472 ". returning zero instead.", ret_val);
2473 return 0;
2474 }
2475 return ret_val;
2476 }
2477
2478 void G1CollectedHeap::prepare_for_verify() {
2479 _verifier->prepare_for_verify();
2480 }
2481
2482 void G1CollectedHeap::verify(VerifyOption vo) {
2483 _verifier->verify(vo);
2484 }
2485
2486 class PrintRegionClosure: public HeapRegionClosure {
2487 outputStream* _st;
2488 public:
2489 PrintRegionClosure(outputStream* st) : _st(st) {}
2490 bool doHeapRegion(HeapRegion* r) {
2491 r->print_on(_st);
2492 return false;
2493 }
2494 };
2495
2496 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2497 const HeapRegion* hr,
2498 const VerifyOption vo) const {
2499 switch (vo) {
2500 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2501 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2502 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2503 default: ShouldNotReachHere();
2504 }
2505 return false; // keep some compilers happy
2506 }
2507
2508 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2509 const VerifyOption vo) const {
2510 switch (vo) {
2511 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2512 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2513 case VerifyOption_G1UseMarkWord: {
2514 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2515 return !obj->is_gc_marked() && !hr->is_archive();
2516 }
2517 default: ShouldNotReachHere();
2518 }
2519 return false; // keep some compilers happy
2520 }
2521
2522 void G1CollectedHeap::print_heap_regions() const {
2523 Log(gc, heap, region) log;
2524 if (log.is_trace()) {
2525 ResourceMark rm;
2526 print_regions_on(log.trace_stream());
2527 }
2528 }
2529
2530 void G1CollectedHeap::print_on(outputStream* st) const {
2531 st->print(" %-20s", "garbage-first heap");
2532 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2533 capacity()/K, used_unlocked()/K);
2534 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2535 p2i(_hrm.reserved().start()),
2536 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2537 p2i(_hrm.reserved().end()));
2538 st->cr();
2539 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2540 uint young_regions = young_regions_count();
2541 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2542 (size_t) young_regions * HeapRegion::GrainBytes / K);
2543 uint survivor_regions = survivor_regions_count();
2544 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2545 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2546 st->cr();
2547 MetaspaceAux::print_on(st);
2548 }
2549
2550 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2551 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2552 "HS=humongous(starts), HC=humongous(continues), "
2553 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2554 "AC=allocation context, "
2555 "TAMS=top-at-mark-start (previous, next)");
2556 PrintRegionClosure blk(st);
2557 heap_region_iterate(&blk);
2558 }
2559
2560 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2561 print_on(st);
2562
2563 // Print the per-region information.
2564 print_regions_on(st);
2565 }
2566
2567 void G1CollectedHeap::print_on_error(outputStream* st) const {
2568 this->CollectedHeap::print_on_error(st);
2569
2570 if (_cm != NULL) {
2571 st->cr();
2572 _cm->print_on_error(st);
2573 }
2574 }
2575
2576 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2577 workers()->print_worker_threads_on(st);
2578 _cmThread->print_on(st);
2579 st->cr();
2580 _cm->print_worker_threads_on(st);
2581 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2582 if (G1StringDedup::is_enabled()) {
2583 G1StringDedup::print_worker_threads_on(st);
2584 }
2585 }
2586
2587 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2588 workers()->threads_do(tc);
2589 tc->do_thread(_cmThread);
2590 _cm->threads_do(tc);
2591 _cg1r->threads_do(tc); // also iterates over the sample thread
2592 if (G1StringDedup::is_enabled()) {
2593 G1StringDedup::threads_do(tc);
2594 }
2595 }
2596
2597 void G1CollectedHeap::print_tracing_info() const {
2598 g1_rem_set()->print_summary_info();
2599 concurrent_mark()->print_summary_info();
2600 }
2601
2602 #ifndef PRODUCT
2603 // Helpful for debugging RSet issues.
2604
2605 class PrintRSetsClosure : public HeapRegionClosure {
2606 private:
2607 const char* _msg;
2608 size_t _occupied_sum;
2609
2610 public:
2611 bool doHeapRegion(HeapRegion* r) {
2612 HeapRegionRemSet* hrrs = r->rem_set();
2613 size_t occupied = hrrs->occupied();
2614 _occupied_sum += occupied;
2615
2616 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2617 if (occupied == 0) {
2618 tty->print_cr(" RSet is empty");
2619 } else {
2620 hrrs->print();
2621 }
2622 tty->print_cr("----------");
2623 return false;
2624 }
2625
2626 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2627 tty->cr();
2628 tty->print_cr("========================================");
2629 tty->print_cr("%s", msg);
2630 tty->cr();
2631 }
2632
2633 ~PrintRSetsClosure() {
2634 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2635 tty->print_cr("========================================");
2636 tty->cr();
2637 }
2638 };
2639
2640 void G1CollectedHeap::print_cset_rsets() {
2641 PrintRSetsClosure cl("Printing CSet RSets");
2642 collection_set_iterate(&cl);
2643 }
2644
2645 void G1CollectedHeap::print_all_rsets() {
2646 PrintRSetsClosure cl("Printing All RSets");;
2647 heap_region_iterate(&cl);
2648 }
2649 #endif // PRODUCT
2650
2651 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2652
2653 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2654 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2655 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2656
2657 size_t eden_capacity_bytes =
2658 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2659
2660 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2661 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2662 eden_capacity_bytes, survivor_used_bytes, num_regions());
2663 }
2664
2665 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2666 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2667 stats->unused(), stats->used(), stats->region_end_waste(),
2668 stats->regions_filled(), stats->direct_allocated(),
2669 stats->failure_used(), stats->failure_waste());
2670 }
2671
2672 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2673 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2674 gc_tracer->report_gc_heap_summary(when, heap_summary);
2675
2676 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2677 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2678 }
2679
2680 G1CollectedHeap* G1CollectedHeap::heap() {
2681 CollectedHeap* heap = GC::gc()->heap();
2682 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2683 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2684 return (G1CollectedHeap*)heap;
2685 }
2686
2687 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2688 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2689
2690 double start = os::elapsedTime();
2691 // Fill TLAB's and such
2692 accumulate_statistics_all_tlabs();
2693 ensure_parsability(true);
2694 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2695
2696 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2697 }
2698
2699 void G1CollectedHeap::gc_epilogue(bool full) {
2700 // we are at the end of the GC. Total collections has already been increased.
2701 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2702
2703 // FIXME: what is this about?
2704 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2705 // is set.
2706 #if defined(COMPILER2) || INCLUDE_JVMCI
2707 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2708 #endif
2709
2710 double start = os::elapsedTime();
2711 resize_all_tlabs();
2712 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2713
2714 allocation_context_stats().update(full);
2715
2716 // We have just completed a GC. Update the soft reference
2717 // policy with the new heap occupancy
2718 Universe::update_heap_info_at_gc();
2719 }
2720
2721 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2722 uint gc_count_before,
2723 bool* succeeded,
2724 GCCause::Cause gc_cause) {
2725 assert_heap_not_locked_and_not_at_safepoint();
2726 VM_G1IncCollectionPause op(gc_count_before,
2727 word_size,
2728 false, /* should_initiate_conc_mark */
2729 g1_policy()->max_pause_time_ms(),
2730 gc_cause);
2731
2732 op.set_allocation_context(AllocationContext::current());
2733 VMThread::execute(&op);
2734
2735 HeapWord* result = op.result();
2736 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2737 assert(result == NULL || ret_succeeded,
2738 "the result should be NULL if the VM did not succeed");
2739 *succeeded = ret_succeeded;
2740
2741 assert_heap_not_locked();
2742 return result;
2743 }
2744
2745 void
2746 G1CollectedHeap::doConcurrentMark() {
2747 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2748 if (!_cmThread->in_progress()) {
2749 _cmThread->set_started();
2750 CGC_lock->notify();
2751 }
2752 }
2753
2754 size_t G1CollectedHeap::pending_card_num() {
2755 size_t extra_cards = 0;
2756 JavaThread *curr = Threads::first();
2757 while (curr != NULL) {
2758 DirtyCardQueue& dcq = curr->dirty_card_queue();
2759 extra_cards += dcq.size();
2760 curr = curr->next();
2761 }
2762 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2763 size_t buffer_size = dcqs.buffer_size();
2764 size_t buffer_num = dcqs.completed_buffers_num();
2765
2766 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2767 // in bytes - not the number of 'entries'. We need to convert
2768 // into a number of cards.
2769 return (buffer_size * buffer_num + extra_cards) / oopSize;
2770 }
2771
2772 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2773 private:
2774 size_t _total_humongous;
2775 size_t _candidate_humongous;
2776
2777 DirtyCardQueue _dcq;
2778
2779 // We don't nominate objects with many remembered set entries, on
2780 // the assumption that such objects are likely still live.
2781 bool is_remset_small(HeapRegion* region) const {
2782 HeapRegionRemSet* const rset = region->rem_set();
2783 return G1EagerReclaimHumongousObjectsWithStaleRefs
2784 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2785 : rset->is_empty();
2786 }
2787
2788 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2789 assert(region->is_starts_humongous(), "Must start a humongous object");
2790
2791 oop obj = oop(region->bottom());
2792
2793 // Dead objects cannot be eager reclaim candidates. Due to class
2794 // unloading it is unsafe to query their classes so we return early.
2795 if (heap->is_obj_dead(obj, region)) {
2796 return false;
2797 }
2798
2799 // Candidate selection must satisfy the following constraints
2800 // while concurrent marking is in progress:
2801 //
2802 // * In order to maintain SATB invariants, an object must not be
2803 // reclaimed if it was allocated before the start of marking and
2804 // has not had its references scanned. Such an object must have
2805 // its references (including type metadata) scanned to ensure no
2806 // live objects are missed by the marking process. Objects
2807 // allocated after the start of concurrent marking don't need to
2808 // be scanned.
2809 //
2810 // * An object must not be reclaimed if it is on the concurrent
2811 // mark stack. Objects allocated after the start of concurrent
2812 // marking are never pushed on the mark stack.
2813 //
2814 // Nominating only objects allocated after the start of concurrent
2815 // marking is sufficient to meet both constraints. This may miss
2816 // some objects that satisfy the constraints, but the marking data
2817 // structures don't support efficiently performing the needed
2818 // additional tests or scrubbing of the mark stack.
2819 //
2820 // However, we presently only nominate is_typeArray() objects.
2821 // A humongous object containing references induces remembered
2822 // set entries on other regions. In order to reclaim such an
2823 // object, those remembered sets would need to be cleaned up.
2824 //
2825 // We also treat is_typeArray() objects specially, allowing them
2826 // to be reclaimed even if allocated before the start of
2827 // concurrent mark. For this we rely on mark stack insertion to
2828 // exclude is_typeArray() objects, preventing reclaiming an object
2829 // that is in the mark stack. We also rely on the metadata for
2830 // such objects to be built-in and so ensured to be kept live.
2831 // Frequent allocation and drop of large binary blobs is an
2832 // important use case for eager reclaim, and this special handling
2833 // may reduce needed headroom.
2834
2835 return obj->is_typeArray() && is_remset_small(region);
2836 }
2837
2838 public:
2839 RegisterHumongousWithInCSetFastTestClosure()
2840 : _total_humongous(0),
2841 _candidate_humongous(0),
2842 _dcq(&JavaThread::dirty_card_queue_set()) {
2843 }
2844
2845 virtual bool doHeapRegion(HeapRegion* r) {
2846 if (!r->is_starts_humongous()) {
2847 return false;
2848 }
2849 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2850
2851 bool is_candidate = humongous_region_is_candidate(g1h, r);
2852 uint rindex = r->hrm_index();
2853 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2854 if (is_candidate) {
2855 _candidate_humongous++;
2856 g1h->register_humongous_region_with_cset(rindex);
2857 // Is_candidate already filters out humongous object with large remembered sets.
2858 // If we have a humongous object with a few remembered sets, we simply flush these
2859 // remembered set entries into the DCQS. That will result in automatic
2860 // re-evaluation of their remembered set entries during the following evacuation
2861 // phase.
2862 if (!r->rem_set()->is_empty()) {
2863 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2864 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2865 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2866 HeapRegionRemSetIterator hrrs(r->rem_set());
2867 size_t card_index;
2868 while (hrrs.has_next(card_index)) {
2869 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2870 // The remembered set might contain references to already freed
2871 // regions. Filter out such entries to avoid failing card table
2872 // verification.
2873 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2874 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2875 *card_ptr = CardTableModRefBS::dirty_card_val();
2876 _dcq.enqueue(card_ptr);
2877 }
2878 }
2879 }
2880 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2881 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2882 hrrs.n_yielded(), r->rem_set()->occupied());
2883 r->rem_set()->clear_locked();
2884 }
2885 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2886 }
2887 _total_humongous++;
2888
2889 return false;
2890 }
2891
2892 size_t total_humongous() const { return _total_humongous; }
2893 size_t candidate_humongous() const { return _candidate_humongous; }
2894
2895 void flush_rem_set_entries() { _dcq.flush(); }
2896 };
2897
2898 void G1CollectedHeap::register_humongous_regions_with_cset() {
2899 if (!G1EagerReclaimHumongousObjects) {
2900 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2901 return;
2902 }
2903 double time = os::elapsed_counter();
2904
2905 // Collect reclaim candidate information and register candidates with cset.
2906 RegisterHumongousWithInCSetFastTestClosure cl;
2907 heap_region_iterate(&cl);
2908
2909 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2910 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2911 cl.total_humongous(),
2912 cl.candidate_humongous());
2913 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2914
2915 // Finally flush all remembered set entries to re-check into the global DCQS.
2916 cl.flush_rem_set_entries();
2917 }
2918
2919 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2920 public:
2921 bool doHeapRegion(HeapRegion* hr) {
2922 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2923 hr->verify_rem_set();
2924 }
2925 return false;
2926 }
2927 };
2928
2929 uint G1CollectedHeap::num_task_queues() const {
2930 return _task_queues->size();
2931 }
2932
2933 #if TASKQUEUE_STATS
2934 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2935 st->print_raw_cr("GC Task Stats");
2936 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2937 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2938 }
2939
2940 void G1CollectedHeap::print_taskqueue_stats() const {
2941 if (!log_is_enabled(Trace, gc, task, stats)) {
2942 return;
2943 }
2944 Log(gc, task, stats) log;
2945 ResourceMark rm;
2946 outputStream* st = log.trace_stream();
2947
2948 print_taskqueue_stats_hdr(st);
2949
2950 TaskQueueStats totals;
2951 const uint n = num_task_queues();
2952 for (uint i = 0; i < n; ++i) {
2953 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2954 totals += task_queue(i)->stats;
2955 }
2956 st->print_raw("tot "); totals.print(st); st->cr();
2957
2958 DEBUG_ONLY(totals.verify());
2959 }
2960
2961 void G1CollectedHeap::reset_taskqueue_stats() {
2962 const uint n = num_task_queues();
2963 for (uint i = 0; i < n; ++i) {
2964 task_queue(i)->stats.reset();
2965 }
2966 }
2967 #endif // TASKQUEUE_STATS
2968
2969 void G1CollectedHeap::wait_for_root_region_scanning() {
2970 double scan_wait_start = os::elapsedTime();
2971 // We have to wait until the CM threads finish scanning the
2972 // root regions as it's the only way to ensure that all the
2973 // objects on them have been correctly scanned before we start
2974 // moving them during the GC.
2975 bool waited = _cm->root_regions()->wait_until_scan_finished();
2976 double wait_time_ms = 0.0;
2977 if (waited) {
2978 double scan_wait_end = os::elapsedTime();
2979 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2980 }
2981 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2982 }
2983
2984 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2985 private:
2986 G1HRPrinter* _hr_printer;
2987 public:
2988 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2989
2990 virtual bool doHeapRegion(HeapRegion* r) {
2991 _hr_printer->cset(r);
2992 return false;
2993 }
2994 };
2995
2996 void G1CollectedHeap::start_new_collection_set() {
2997 collection_set()->start_incremental_building();
2998
2999 clear_cset_fast_test();
3000
3001 guarantee(_eden.length() == 0, "eden should have been cleared");
3002 g1_policy()->transfer_survivors_to_cset(survivor());
3003 }
3004
3005 bool
3006 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3007 assert_at_safepoint(true /* should_be_vm_thread */);
3008 guarantee(!is_gc_active(), "collection is not reentrant");
3009
3010 if (GCLocker::check_active_before_gc()) {
3011 return false;
3012 }
3013
3014 _gc_timer_stw->register_gc_start();
3015
3016 GCIdMark gc_id_mark;
3017 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3018
3019 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3020 ResourceMark rm;
3021
3022 g1_policy()->note_gc_start();
3023
3024 wait_for_root_region_scanning();
3025
3026 print_heap_before_gc();
3027 print_heap_regions();
3028 trace_heap_before_gc(_gc_tracer_stw);
3029
3030 _verifier->verify_region_sets_optional();
3031 _verifier->verify_dirty_young_regions();
3032
3033 // We should not be doing initial mark unless the conc mark thread is running
3034 if (!_cmThread->should_terminate()) {
3035 // This call will decide whether this pause is an initial-mark
3036 // pause. If it is, during_initial_mark_pause() will return true
3037 // for the duration of this pause.
3038 g1_policy()->decide_on_conc_mark_initiation();
3039 }
3040
3041 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3042 assert(!collector_state()->during_initial_mark_pause() ||
3043 collector_state()->gcs_are_young(), "sanity");
3044
3045 // We also do not allow mixed GCs during marking.
3046 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3047
3048 // Record whether this pause is an initial mark. When the current
3049 // thread has completed its logging output and it's safe to signal
3050 // the CM thread, the flag's value in the policy has been reset.
3051 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3052
3053 // Inner scope for scope based logging, timers, and stats collection
3054 {
3055 EvacuationInfo evacuation_info;
3056
3057 if (collector_state()->during_initial_mark_pause()) {
3058 // We are about to start a marking cycle, so we increment the
3059 // full collection counter.
3060 increment_old_marking_cycles_started();
3061 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3062 }
3063
3064 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3065
3066 GCTraceCPUTime tcpu;
3067
3068 FormatBuffer<> gc_string("Pause ");
3069 if (collector_state()->during_initial_mark_pause()) {
3070 gc_string.append("Initial Mark");
3071 } else if (collector_state()->gcs_are_young()) {
3072 gc_string.append("Young");
3073 } else {
3074 gc_string.append("Mixed");
3075 }
3076 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3077
3078 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3079 workers()->active_workers(),
3080 Threads::number_of_non_daemon_threads());
3081 workers()->update_active_workers(active_workers);
3082 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3083
3084 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3085 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3086
3087 // If the secondary_free_list is not empty, append it to the
3088 // free_list. No need to wait for the cleanup operation to finish;
3089 // the region allocation code will check the secondary_free_list
3090 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3091 // set, skip this step so that the region allocation code has to
3092 // get entries from the secondary_free_list.
3093 if (!G1StressConcRegionFreeing) {
3094 append_secondary_free_list_if_not_empty_with_lock();
3095 }
3096
3097 G1HeapTransition heap_transition(this);
3098 size_t heap_used_bytes_before_gc = used();
3099
3100 // Don't dynamically change the number of GC threads this early. A value of
3101 // 0 is used to indicate serial work. When parallel work is done,
3102 // it will be set.
3103
3104 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3105 IsGCActiveMark x;
3106
3107 gc_prologue(false);
3108 increment_total_collections(false /* full gc */);
3109 increment_gc_time_stamp();
3110
3111 if (VerifyRememberedSets) {
3112 log_info(gc, verify)("[Verifying RemSets before GC]");
3113 VerifyRegionRemSetClosure v_cl;
3114 heap_region_iterate(&v_cl);
3115 }
3116
3117 _verifier->verify_before_gc();
3118
3119 _verifier->check_bitmaps("GC Start");
3120
3121 #if defined(COMPILER2) || INCLUDE_JVMCI
3122 DerivedPointerTable::clear();
3123 #endif
3124
3125 // Please see comment in g1CollectedHeap.hpp and
3126 // G1CollectedHeap::ref_processing_init() to see how
3127 // reference processing currently works in G1.
3128
3129 // Enable discovery in the STW reference processor
3130 if (g1_policy()->should_process_references()) {
3131 ref_processor_stw()->enable_discovery();
3132 } else {
3133 ref_processor_stw()->disable_discovery();
3134 }
3135
3136 {
3137 // We want to temporarily turn off discovery by the
3138 // CM ref processor, if necessary, and turn it back on
3139 // on again later if we do. Using a scoped
3140 // NoRefDiscovery object will do this.
3141 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3142
3143 // Forget the current alloc region (we might even choose it to be part
3144 // of the collection set!).
3145 _allocator->release_mutator_alloc_region();
3146
3147 // This timing is only used by the ergonomics to handle our pause target.
3148 // It is unclear why this should not include the full pause. We will
3149 // investigate this in CR 7178365.
3150 //
3151 // Preserving the old comment here if that helps the investigation:
3152 //
3153 // The elapsed time induced by the start time below deliberately elides
3154 // the possible verification above.
3155 double sample_start_time_sec = os::elapsedTime();
3156
3157 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3158
3159 if (collector_state()->during_initial_mark_pause()) {
3160 concurrent_mark()->checkpointRootsInitialPre();
3161 }
3162
3163 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3164
3165 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3166
3167 // Make sure the remembered sets are up to date. This needs to be
3168 // done before register_humongous_regions_with_cset(), because the
3169 // remembered sets are used there to choose eager reclaim candidates.
3170 // If the remembered sets are not up to date we might miss some
3171 // entries that need to be handled.
3172 g1_rem_set()->cleanupHRRS();
3173
3174 register_humongous_regions_with_cset();
3175
3176 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3177
3178 // We call this after finalize_cset() to
3179 // ensure that the CSet has been finalized.
3180 _cm->verify_no_cset_oops();
3181
3182 if (_hr_printer.is_active()) {
3183 G1PrintCollectionSetClosure cl(&_hr_printer);
3184 _collection_set.iterate(&cl);
3185 }
3186
3187 // Initialize the GC alloc regions.
3188 _allocator->init_gc_alloc_regions(evacuation_info);
3189
3190 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3191 pre_evacuate_collection_set();
3192
3193 // Actually do the work...
3194 evacuate_collection_set(evacuation_info, &per_thread_states);
3195
3196 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3197
3198 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3199 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3200
3201 eagerly_reclaim_humongous_regions();
3202
3203 record_obj_copy_mem_stats();
3204 _survivor_evac_stats.adjust_desired_plab_sz();
3205 _old_evac_stats.adjust_desired_plab_sz();
3206
3207 double start = os::elapsedTime();
3208 start_new_collection_set();
3209 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3210
3211 if (evacuation_failed()) {
3212 set_used(recalculate_used());
3213 if (_archive_allocator != NULL) {
3214 _archive_allocator->clear_used();
3215 }
3216 for (uint i = 0; i < ParallelGCThreads; i++) {
3217 if (_evacuation_failed_info_array[i].has_failed()) {
3218 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3219 }
3220 }
3221 } else {
3222 // The "used" of the the collection set have already been subtracted
3223 // when they were freed. Add in the bytes evacuated.
3224 increase_used(g1_policy()->bytes_copied_during_gc());
3225 }
3226
3227 if (collector_state()->during_initial_mark_pause()) {
3228 // We have to do this before we notify the CM threads that
3229 // they can start working to make sure that all the
3230 // appropriate initialization is done on the CM object.
3231 concurrent_mark()->checkpointRootsInitialPost();
3232 collector_state()->set_mark_in_progress(true);
3233 // Note that we don't actually trigger the CM thread at
3234 // this point. We do that later when we're sure that
3235 // the current thread has completed its logging output.
3236 }
3237
3238 allocate_dummy_regions();
3239
3240 _allocator->init_mutator_alloc_region();
3241
3242 {
3243 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3244 if (expand_bytes > 0) {
3245 size_t bytes_before = capacity();
3246 // No need for an ergo logging here,
3247 // expansion_amount() does this when it returns a value > 0.
3248 double expand_ms;
3249 if (!expand(expand_bytes, _workers, &expand_ms)) {
3250 // We failed to expand the heap. Cannot do anything about it.
3251 }
3252 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3253 }
3254 }
3255
3256 // We redo the verification but now wrt to the new CSet which
3257 // has just got initialized after the previous CSet was freed.
3258 _cm->verify_no_cset_oops();
3259
3260 // This timing is only used by the ergonomics to handle our pause target.
3261 // It is unclear why this should not include the full pause. We will
3262 // investigate this in CR 7178365.
3263 double sample_end_time_sec = os::elapsedTime();
3264 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3265 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3266 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3267
3268 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3269 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3270
3271 MemoryService::track_memory_usage();
3272
3273 // In prepare_for_verify() below we'll need to scan the deferred
3274 // update buffers to bring the RSets up-to-date if
3275 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3276 // the update buffers we'll probably need to scan cards on the
3277 // regions we just allocated to (i.e., the GC alloc
3278 // regions). However, during the last GC we called
3279 // set_saved_mark() on all the GC alloc regions, so card
3280 // scanning might skip the [saved_mark_word()...top()] area of
3281 // those regions (i.e., the area we allocated objects into
3282 // during the last GC). But it shouldn't. Given that
3283 // saved_mark_word() is conditional on whether the GC time stamp
3284 // on the region is current or not, by incrementing the GC time
3285 // stamp here we invalidate all the GC time stamps on all the
3286 // regions and saved_mark_word() will simply return top() for
3287 // all the regions. This is a nicer way of ensuring this rather
3288 // than iterating over the regions and fixing them. In fact, the
3289 // GC time stamp increment here also ensures that
3290 // saved_mark_word() will return top() between pauses, i.e.,
3291 // during concurrent refinement. So we don't need the
3292 // is_gc_active() check to decided which top to use when
3293 // scanning cards (see CR 7039627).
3294 increment_gc_time_stamp();
3295
3296 if (VerifyRememberedSets) {
3297 log_info(gc, verify)("[Verifying RemSets after GC]");
3298 VerifyRegionRemSetClosure v_cl;
3299 heap_region_iterate(&v_cl);
3300 }
3301
3302 _verifier->verify_after_gc();
3303 _verifier->check_bitmaps("GC End");
3304
3305 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3306 ref_processor_stw()->verify_no_references_recorded();
3307
3308 // CM reference discovery will be re-enabled if necessary.
3309 }
3310
3311 #ifdef TRACESPINNING
3312 ParallelTaskTerminator::print_termination_counts();
3313 #endif
3314
3315 gc_epilogue(false);
3316 }
3317
3318 // Print the remainder of the GC log output.
3319 if (evacuation_failed()) {
3320 log_info(gc)("To-space exhausted");
3321 }
3322
3323 g1_policy()->print_phases();
3324 heap_transition.print();
3325
3326 // It is not yet to safe to tell the concurrent mark to
3327 // start as we have some optional output below. We don't want the
3328 // output from the concurrent mark thread interfering with this
3329 // logging output either.
3330
3331 _hrm.verify_optional();
3332 _verifier->verify_region_sets_optional();
3333
3334 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3335 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3336
3337 print_heap_after_gc();
3338 print_heap_regions();
3339 trace_heap_after_gc(_gc_tracer_stw);
3340
3341 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3342 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3343 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3344 // before any GC notifications are raised.
3345 g1mm()->update_sizes();
3346
3347 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3348 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3349 _gc_timer_stw->register_gc_end();
3350 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3351 }
3352 // It should now be safe to tell the concurrent mark thread to start
3353 // without its logging output interfering with the logging output
3354 // that came from the pause.
3355
3356 if (should_start_conc_mark) {
3357 // CAUTION: after the doConcurrentMark() call below,
3358 // the concurrent marking thread(s) could be running
3359 // concurrently with us. Make sure that anything after
3360 // this point does not assume that we are the only GC thread
3361 // running. Note: of course, the actual marking work will
3362 // not start until the safepoint itself is released in
3363 // SuspendibleThreadSet::desynchronize().
3364 doConcurrentMark();
3365 }
3366
3367 return true;
3368 }
3369
3370 void G1CollectedHeap::remove_self_forwarding_pointers() {
3371 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3372 workers()->run_task(&rsfp_task);
3373 }
3374
3375 void G1CollectedHeap::restore_after_evac_failure() {
3376 double remove_self_forwards_start = os::elapsedTime();
3377
3378 remove_self_forwarding_pointers();
3379 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3380 _preserved_marks_set.restore(&task_executor);
3381
3382 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3383 }
3384
3385 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3386 if (!_evacuation_failed) {
3387 _evacuation_failed = true;
3388 }
3389
3390 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3391 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3392 }
3393
3394 bool G1ParEvacuateFollowersClosure::offer_termination() {
3395 G1ParScanThreadState* const pss = par_scan_state();
3396 start_term_time();
3397 const bool res = terminator()->offer_termination();
3398 end_term_time();
3399 return res;
3400 }
3401
3402 void G1ParEvacuateFollowersClosure::do_void() {
3403 G1ParScanThreadState* const pss = par_scan_state();
3404 pss->trim_queue();
3405 do {
3406 pss->steal_and_trim_queue(queues());
3407 } while (!offer_termination());
3408 }
3409
3410 class G1ParTask : public AbstractGangTask {
3411 protected:
3412 G1CollectedHeap* _g1h;
3413 G1ParScanThreadStateSet* _pss;
3414 RefToScanQueueSet* _queues;
3415 G1RootProcessor* _root_processor;
3416 ParallelTaskTerminator _terminator;
3417 uint _n_workers;
3418
3419 public:
3420 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3421 : AbstractGangTask("G1 collection"),
3422 _g1h(g1h),
3423 _pss(per_thread_states),
3424 _queues(task_queues),
3425 _root_processor(root_processor),
3426 _terminator(n_workers, _queues),
3427 _n_workers(n_workers)
3428 {}
3429
3430 void work(uint worker_id) {
3431 if (worker_id >= _n_workers) return; // no work needed this round
3432
3433 double start_sec = os::elapsedTime();
3434 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3435
3436 {
3437 ResourceMark rm;
3438 HandleMark hm;
3439
3440 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3441
3442 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3443 pss->set_ref_processor(rp);
3444
3445 double start_strong_roots_sec = os::elapsedTime();
3446
3447 _root_processor->evacuate_roots(pss->closures(), worker_id);
3448
3449 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3450
3451 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3452 // treating the nmethods visited to act as roots for concurrent marking.
3453 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3454 // objects copied by the current evacuation.
3455 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3456 pss->closures()->weak_codeblobs(),
3457 worker_id);
3458
3459 _pss->add_cards_scanned(worker_id, cards_scanned);
3460
3461 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3462
3463 double term_sec = 0.0;
3464 size_t evac_term_attempts = 0;
3465 {
3466 double start = os::elapsedTime();
3467 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3468 evac.do_void();
3469
3470 evac_term_attempts = evac.term_attempts();
3471 term_sec = evac.term_time();
3472 double elapsed_sec = os::elapsedTime() - start;
3473 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3474 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3475 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3476 }
3477
3478 assert(pss->queue_is_empty(), "should be empty");
3479
3480 if (log_is_enabled(Debug, gc, task, stats)) {
3481 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3482 size_t lab_waste;
3483 size_t lab_undo_waste;
3484 pss->waste(lab_waste, lab_undo_waste);
3485 _g1h->print_termination_stats(worker_id,
3486 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3487 strong_roots_sec * 1000.0, /* strong roots time */
3488 term_sec * 1000.0, /* evac term time */
3489 evac_term_attempts, /* evac term attempts */
3490 lab_waste, /* alloc buffer waste */
3491 lab_undo_waste /* undo waste */
3492 );
3493 }
3494
3495 // Close the inner scope so that the ResourceMark and HandleMark
3496 // destructors are executed here and are included as part of the
3497 // "GC Worker Time".
3498 }
3499 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3500 }
3501 };
3502
3503 void G1CollectedHeap::print_termination_stats_hdr() {
3504 log_debug(gc, task, stats)("GC Termination Stats");
3505 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3506 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3507 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3508 }
3509
3510 void G1CollectedHeap::print_termination_stats(uint worker_id,
3511 double elapsed_ms,
3512 double strong_roots_ms,
3513 double term_ms,
3514 size_t term_attempts,
3515 size_t alloc_buffer_waste,
3516 size_t undo_waste) const {
3517 log_debug(gc, task, stats)
3518 ("%3d %9.2f %9.2f %6.2f "
3519 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3520 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3521 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3522 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3523 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3524 alloc_buffer_waste * HeapWordSize / K,
3525 undo_waste * HeapWordSize / K);
3526 }
3527
3528 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3529 private:
3530 BoolObjectClosure* _is_alive;
3531 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3532
3533 int _initial_string_table_size;
3534 int _initial_symbol_table_size;
3535
3536 bool _process_strings;
3537 int _strings_processed;
3538 int _strings_removed;
3539
3540 bool _process_symbols;
3541 int _symbols_processed;
3542 int _symbols_removed;
3543
3544 bool _process_string_dedup;
3545
3546 public:
3547 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3548 AbstractGangTask("String/Symbol Unlinking"),
3549 _is_alive(is_alive),
3550 _dedup_closure(is_alive, NULL, false),
3551 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3552 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3553 _process_string_dedup(process_string_dedup) {
3554
3555 _initial_string_table_size = StringTable::the_table()->table_size();
3556 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3557 if (process_strings) {
3558 StringTable::clear_parallel_claimed_index();
3559 }
3560 if (process_symbols) {
3561 SymbolTable::clear_parallel_claimed_index();
3562 }
3563 }
3564
3565 ~G1StringAndSymbolCleaningTask() {
3566 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3567 "claim value %d after unlink less than initial string table size %d",
3568 StringTable::parallel_claimed_index(), _initial_string_table_size);
3569 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3570 "claim value %d after unlink less than initial symbol table size %d",
3571 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3572
3573 log_info(gc, stringtable)(
3574 "Cleaned string and symbol table, "
3575 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3576 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3577 strings_processed(), strings_removed(),
3578 symbols_processed(), symbols_removed());
3579 }
3580
3581 void work(uint worker_id) {
3582 int strings_processed = 0;
3583 int strings_removed = 0;
3584 int symbols_processed = 0;
3585 int symbols_removed = 0;
3586 if (_process_strings) {
3587 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3588 Atomic::add(strings_processed, &_strings_processed);
3589 Atomic::add(strings_removed, &_strings_removed);
3590 }
3591 if (_process_symbols) {
3592 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3593 Atomic::add(symbols_processed, &_symbols_processed);
3594 Atomic::add(symbols_removed, &_symbols_removed);
3595 }
3596 if (_process_string_dedup) {
3597 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3598 }
3599 }
3600
3601 size_t strings_processed() const { return (size_t)_strings_processed; }
3602 size_t strings_removed() const { return (size_t)_strings_removed; }
3603
3604 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3605 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3606 };
3607
3608 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3609 private:
3610 static Monitor* _lock;
3611
3612 BoolObjectClosure* const _is_alive;
3613 const bool _unloading_occurred;
3614 const uint _num_workers;
3615
3616 // Variables used to claim nmethods.
3617 CompiledMethod* _first_nmethod;
3618 volatile CompiledMethod* _claimed_nmethod;
3619
3620 // The list of nmethods that need to be processed by the second pass.
3621 volatile CompiledMethod* _postponed_list;
3622 volatile uint _num_entered_barrier;
3623
3624 public:
3625 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3626 _is_alive(is_alive),
3627 _unloading_occurred(unloading_occurred),
3628 _num_workers(num_workers),
3629 _first_nmethod(NULL),
3630 _claimed_nmethod(NULL),
3631 _postponed_list(NULL),
3632 _num_entered_barrier(0)
3633 {
3634 CompiledMethod::increase_unloading_clock();
3635 // Get first alive nmethod
3636 CompiledMethodIterator iter = CompiledMethodIterator();
3637 if(iter.next_alive()) {
3638 _first_nmethod = iter.method();
3639 }
3640 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3641 }
3642
3643 ~G1CodeCacheUnloadingTask() {
3644 CodeCache::verify_clean_inline_caches();
3645
3646 CodeCache::set_needs_cache_clean(false);
3647 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3648
3649 CodeCache::verify_icholder_relocations();
3650 }
3651
3652 private:
3653 void add_to_postponed_list(CompiledMethod* nm) {
3654 CompiledMethod* old;
3655 do {
3656 old = (CompiledMethod*)_postponed_list;
3657 nm->set_unloading_next(old);
3658 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3659 }
3660
3661 void clean_nmethod(CompiledMethod* nm) {
3662 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3663
3664 if (postponed) {
3665 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3666 add_to_postponed_list(nm);
3667 }
3668
3669 // Mark that this thread has been cleaned/unloaded.
3670 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3671 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3672 }
3673
3674 void clean_nmethod_postponed(CompiledMethod* nm) {
3675 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3676 }
3677
3678 static const int MaxClaimNmethods = 16;
3679
3680 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3681 CompiledMethod* first;
3682 CompiledMethodIterator last;
3683
3684 do {
3685 *num_claimed_nmethods = 0;
3686
3687 first = (CompiledMethod*)_claimed_nmethod;
3688 last = CompiledMethodIterator(first);
3689
3690 if (first != NULL) {
3691
3692 for (int i = 0; i < MaxClaimNmethods; i++) {
3693 if (!last.next_alive()) {
3694 break;
3695 }
3696 claimed_nmethods[i] = last.method();
3697 (*num_claimed_nmethods)++;
3698 }
3699 }
3700
3701 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3702 }
3703
3704 CompiledMethod* claim_postponed_nmethod() {
3705 CompiledMethod* claim;
3706 CompiledMethod* next;
3707
3708 do {
3709 claim = (CompiledMethod*)_postponed_list;
3710 if (claim == NULL) {
3711 return NULL;
3712 }
3713
3714 next = claim->unloading_next();
3715
3716 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3717
3718 return claim;
3719 }
3720
3721 public:
3722 // Mark that we're done with the first pass of nmethod cleaning.
3723 void barrier_mark(uint worker_id) {
3724 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3725 _num_entered_barrier++;
3726 if (_num_entered_barrier == _num_workers) {
3727 ml.notify_all();
3728 }
3729 }
3730
3731 // See if we have to wait for the other workers to
3732 // finish their first-pass nmethod cleaning work.
3733 void barrier_wait(uint worker_id) {
3734 if (_num_entered_barrier < _num_workers) {
3735 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3736 while (_num_entered_barrier < _num_workers) {
3737 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3738 }
3739 }
3740 }
3741
3742 // Cleaning and unloading of nmethods. Some work has to be postponed
3743 // to the second pass, when we know which nmethods survive.
3744 void work_first_pass(uint worker_id) {
3745 // The first nmethods is claimed by the first worker.
3746 if (worker_id == 0 && _first_nmethod != NULL) {
3747 clean_nmethod(_first_nmethod);
3748 _first_nmethod = NULL;
3749 }
3750
3751 int num_claimed_nmethods;
3752 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3753
3754 while (true) {
3755 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3756
3757 if (num_claimed_nmethods == 0) {
3758 break;
3759 }
3760
3761 for (int i = 0; i < num_claimed_nmethods; i++) {
3762 clean_nmethod(claimed_nmethods[i]);
3763 }
3764 }
3765 }
3766
3767 void work_second_pass(uint worker_id) {
3768 CompiledMethod* nm;
3769 // Take care of postponed nmethods.
3770 while ((nm = claim_postponed_nmethod()) != NULL) {
3771 clean_nmethod_postponed(nm);
3772 }
3773 }
3774 };
3775
3776 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3777
3778 class G1KlassCleaningTask : public StackObj {
3779 BoolObjectClosure* _is_alive;
3780 volatile jint _clean_klass_tree_claimed;
3781 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3782
3783 public:
3784 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3785 _is_alive(is_alive),
3786 _clean_klass_tree_claimed(0),
3787 _klass_iterator() {
3788 }
3789
3790 private:
3791 bool claim_clean_klass_tree_task() {
3792 if (_clean_klass_tree_claimed) {
3793 return false;
3794 }
3795
3796 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3797 }
3798
3799 InstanceKlass* claim_next_klass() {
3800 Klass* klass;
3801 do {
3802 klass =_klass_iterator.next_klass();
3803 } while (klass != NULL && !klass->is_instance_klass());
3804
3805 // this can be null so don't call InstanceKlass::cast
3806 return static_cast<InstanceKlass*>(klass);
3807 }
3808
3809 public:
3810
3811 void clean_klass(InstanceKlass* ik) {
3812 ik->clean_weak_instanceklass_links(_is_alive);
3813 }
3814
3815 void work() {
3816 ResourceMark rm;
3817
3818 // One worker will clean the subklass/sibling klass tree.
3819 if (claim_clean_klass_tree_task()) {
3820 Klass::clean_subklass_tree(_is_alive);
3821 }
3822
3823 // All workers will help cleaning the classes,
3824 InstanceKlass* klass;
3825 while ((klass = claim_next_klass()) != NULL) {
3826 clean_klass(klass);
3827 }
3828 }
3829 };
3830
3831 // To minimize the remark pause times, the tasks below are done in parallel.
3832 class G1ParallelCleaningTask : public AbstractGangTask {
3833 private:
3834 G1StringAndSymbolCleaningTask _string_symbol_task;
3835 G1CodeCacheUnloadingTask _code_cache_task;
3836 G1KlassCleaningTask _klass_cleaning_task;
3837
3838 public:
3839 // The constructor is run in the VMThread.
3840 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3841 AbstractGangTask("Parallel Cleaning"),
3842 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3843 _code_cache_task(num_workers, is_alive, unloading_occurred),
3844 _klass_cleaning_task(is_alive) {
3845 }
3846
3847 // The parallel work done by all worker threads.
3848 void work(uint worker_id) {
3849 // Do first pass of code cache cleaning.
3850 _code_cache_task.work_first_pass(worker_id);
3851
3852 // Let the threads mark that the first pass is done.
3853 _code_cache_task.barrier_mark(worker_id);
3854
3855 // Clean the Strings and Symbols.
3856 _string_symbol_task.work(worker_id);
3857
3858 // Wait for all workers to finish the first code cache cleaning pass.
3859 _code_cache_task.barrier_wait(worker_id);
3860
3861 // Do the second code cache cleaning work, which realize on
3862 // the liveness information gathered during the first pass.
3863 _code_cache_task.work_second_pass(worker_id);
3864
3865 // Clean all klasses that were not unloaded.
3866 _klass_cleaning_task.work();
3867 }
3868 };
3869
3870
3871 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3872 bool class_unloading_occurred) {
3873 uint n_workers = workers()->active_workers();
3874
3875 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3876 workers()->run_task(&g1_unlink_task);
3877 }
3878
3879 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3880 bool process_strings,
3881 bool process_symbols,
3882 bool process_string_dedup) {
3883 if (!process_strings && !process_symbols && !process_string_dedup) {
3884 // Nothing to clean.
3885 return;
3886 }
3887
3888 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3889 workers()->run_task(&g1_unlink_task);
3890
3891 }
3892
3893 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3894 private:
3895 DirtyCardQueueSet* _queue;
3896 G1CollectedHeap* _g1h;
3897 public:
3898 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3899 _queue(queue), _g1h(g1h) { }
3900
3901 virtual void work(uint worker_id) {
3902 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3903 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3904
3905 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3906 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3907
3908 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3909 }
3910 };
3911
3912 void G1CollectedHeap::redirty_logged_cards() {
3913 double redirty_logged_cards_start = os::elapsedTime();
3914
3915 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3916 dirty_card_queue_set().reset_for_par_iteration();
3917 workers()->run_task(&redirty_task);
3918
3919 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3920 dcq.merge_bufferlists(&dirty_card_queue_set());
3921 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3922
3923 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3924 }
3925
3926 // Weak Reference Processing support
3927
3928 // An always "is_alive" closure that is used to preserve referents.
3929 // If the object is non-null then it's alive. Used in the preservation
3930 // of referent objects that are pointed to by reference objects
3931 // discovered by the CM ref processor.
3932 class G1AlwaysAliveClosure: public BoolObjectClosure {
3933 G1CollectedHeap* _g1;
3934 public:
3935 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3936 bool do_object_b(oop p) {
3937 if (p != NULL) {
3938 return true;
3939 }
3940 return false;
3941 }
3942 };
3943
3944 bool G1STWIsAliveClosure::do_object_b(oop p) {
3945 // An object is reachable if it is outside the collection set,
3946 // or is inside and copied.
3947 return !_g1->is_in_cset(p) || p->is_forwarded();
3948 }
3949
3950 // Non Copying Keep Alive closure
3951 class G1KeepAliveClosure: public OopClosure {
3952 G1CollectedHeap* _g1;
3953 public:
3954 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3955 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3956 void do_oop(oop* p) {
3957 oop obj = *p;
3958 assert(obj != NULL, "the caller should have filtered out NULL values");
3959
3960 const InCSetState cset_state = _g1->in_cset_state(obj);
3961 if (!cset_state.is_in_cset_or_humongous()) {
3962 return;
3963 }
3964 if (cset_state.is_in_cset()) {
3965 assert( obj->is_forwarded(), "invariant" );
3966 *p = obj->forwardee();
3967 } else {
3968 assert(!obj->is_forwarded(), "invariant" );
3969 assert(cset_state.is_humongous(),
3970 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3971 _g1->set_humongous_is_live(obj);
3972 }
3973 }
3974 };
3975
3976 // Copying Keep Alive closure - can be called from both
3977 // serial and parallel code as long as different worker
3978 // threads utilize different G1ParScanThreadState instances
3979 // and different queues.
3980
3981 class G1CopyingKeepAliveClosure: public OopClosure {
3982 G1CollectedHeap* _g1h;
3983 OopClosure* _copy_non_heap_obj_cl;
3984 G1ParScanThreadState* _par_scan_state;
3985
3986 public:
3987 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3988 OopClosure* non_heap_obj_cl,
3989 G1ParScanThreadState* pss):
3990 _g1h(g1h),
3991 _copy_non_heap_obj_cl(non_heap_obj_cl),
3992 _par_scan_state(pss)
3993 {}
3994
3995 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3996 virtual void do_oop( oop* p) { do_oop_work(p); }
3997
3998 template <class T> void do_oop_work(T* p) {
3999 oop obj = oopDesc::load_decode_heap_oop(p);
4000
4001 if (_g1h->is_in_cset_or_humongous(obj)) {
4002 // If the referent object has been forwarded (either copied
4003 // to a new location or to itself in the event of an
4004 // evacuation failure) then we need to update the reference
4005 // field and, if both reference and referent are in the G1
4006 // heap, update the RSet for the referent.
4007 //
4008 // If the referent has not been forwarded then we have to keep
4009 // it alive by policy. Therefore we have copy the referent.
4010 //
4011 // If the reference field is in the G1 heap then we can push
4012 // on the PSS queue. When the queue is drained (after each
4013 // phase of reference processing) the object and it's followers
4014 // will be copied, the reference field set to point to the
4015 // new location, and the RSet updated. Otherwise we need to
4016 // use the the non-heap or metadata closures directly to copy
4017 // the referent object and update the pointer, while avoiding
4018 // updating the RSet.
4019
4020 if (_g1h->is_in_g1_reserved(p)) {
4021 _par_scan_state->push_on_queue(p);
4022 } else {
4023 assert(!Metaspace::contains((const void*)p),
4024 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4025 _copy_non_heap_obj_cl->do_oop(p);
4026 }
4027 }
4028 }
4029 };
4030
4031 // Serial drain queue closure. Called as the 'complete_gc'
4032 // closure for each discovered list in some of the
4033 // reference processing phases.
4034
4035 class G1STWDrainQueueClosure: public VoidClosure {
4036 protected:
4037 G1CollectedHeap* _g1h;
4038 G1ParScanThreadState* _par_scan_state;
4039
4040 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4041
4042 public:
4043 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4044 _g1h(g1h),
4045 _par_scan_state(pss)
4046 { }
4047
4048 void do_void() {
4049 G1ParScanThreadState* const pss = par_scan_state();
4050 pss->trim_queue();
4051 }
4052 };
4053
4054 // Parallel Reference Processing closures
4055
4056 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4057 // processing during G1 evacuation pauses.
4058
4059 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4060 private:
4061 G1CollectedHeap* _g1h;
4062 G1ParScanThreadStateSet* _pss;
4063 RefToScanQueueSet* _queues;
4064 WorkGang* _workers;
4065 uint _active_workers;
4066
4067 public:
4068 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4069 G1ParScanThreadStateSet* per_thread_states,
4070 WorkGang* workers,
4071 RefToScanQueueSet *task_queues,
4072 uint n_workers) :
4073 _g1h(g1h),
4074 _pss(per_thread_states),
4075 _queues(task_queues),
4076 _workers(workers),
4077 _active_workers(n_workers)
4078 {
4079 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4080 }
4081
4082 // Executes the given task using concurrent marking worker threads.
4083 virtual void execute(ProcessTask& task);
4084 virtual void execute(EnqueueTask& task);
4085 };
4086
4087 // Gang task for possibly parallel reference processing
4088
4089 class G1STWRefProcTaskProxy: public AbstractGangTask {
4090 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4091 ProcessTask& _proc_task;
4092 G1CollectedHeap* _g1h;
4093 G1ParScanThreadStateSet* _pss;
4094 RefToScanQueueSet* _task_queues;
4095 ParallelTaskTerminator* _terminator;
4096
4097 public:
4098 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4099 G1CollectedHeap* g1h,
4100 G1ParScanThreadStateSet* per_thread_states,
4101 RefToScanQueueSet *task_queues,
4102 ParallelTaskTerminator* terminator) :
4103 AbstractGangTask("Process reference objects in parallel"),
4104 _proc_task(proc_task),
4105 _g1h(g1h),
4106 _pss(per_thread_states),
4107 _task_queues(task_queues),
4108 _terminator(terminator)
4109 {}
4110
4111 virtual void work(uint worker_id) {
4112 // The reference processing task executed by a single worker.
4113 ResourceMark rm;
4114 HandleMark hm;
4115
4116 G1STWIsAliveClosure is_alive(_g1h);
4117
4118 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4119 pss->set_ref_processor(NULL);
4120
4121 // Keep alive closure.
4122 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4123
4124 // Complete GC closure
4125 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4126
4127 // Call the reference processing task's work routine.
4128 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4129
4130 // Note we cannot assert that the refs array is empty here as not all
4131 // of the processing tasks (specifically phase2 - pp2_work) execute
4132 // the complete_gc closure (which ordinarily would drain the queue) so
4133 // the queue may not be empty.
4134 }
4135 };
4136
4137 // Driver routine for parallel reference processing.
4138 // Creates an instance of the ref processing gang
4139 // task and has the worker threads execute it.
4140 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4141 assert(_workers != NULL, "Need parallel worker threads.");
4142
4143 ParallelTaskTerminator terminator(_active_workers, _queues);
4144 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4145
4146 _workers->run_task(&proc_task_proxy);
4147 }
4148
4149 // Gang task for parallel reference enqueueing.
4150
4151 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4152 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4153 EnqueueTask& _enq_task;
4154
4155 public:
4156 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4157 AbstractGangTask("Enqueue reference objects in parallel"),
4158 _enq_task(enq_task)
4159 { }
4160
4161 virtual void work(uint worker_id) {
4162 _enq_task.work(worker_id);
4163 }
4164 };
4165
4166 // Driver routine for parallel reference enqueueing.
4167 // Creates an instance of the ref enqueueing gang
4168 // task and has the worker threads execute it.
4169
4170 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4171 assert(_workers != NULL, "Need parallel worker threads.");
4172
4173 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4174
4175 _workers->run_task(&enq_task_proxy);
4176 }
4177
4178 // End of weak reference support closures
4179
4180 // Abstract task used to preserve (i.e. copy) any referent objects
4181 // that are in the collection set and are pointed to by reference
4182 // objects discovered by the CM ref processor.
4183
4184 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4185 protected:
4186 G1CollectedHeap* _g1h;
4187 G1ParScanThreadStateSet* _pss;
4188 RefToScanQueueSet* _queues;
4189 ParallelTaskTerminator _terminator;
4190 uint _n_workers;
4191
4192 public:
4193 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4194 AbstractGangTask("ParPreserveCMReferents"),
4195 _g1h(g1h),
4196 _pss(per_thread_states),
4197 _queues(task_queues),
4198 _terminator(workers, _queues),
4199 _n_workers(workers)
4200 {
4201 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4202 }
4203
4204 void work(uint worker_id) {
4205 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4206
4207 ResourceMark rm;
4208 HandleMark hm;
4209
4210 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4211 pss->set_ref_processor(NULL);
4212 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4213
4214 // Is alive closure
4215 G1AlwaysAliveClosure always_alive(_g1h);
4216
4217 // Copying keep alive closure. Applied to referent objects that need
4218 // to be copied.
4219 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4220
4221 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4222
4223 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4224 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4225
4226 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4227 // So this must be true - but assert just in case someone decides to
4228 // change the worker ids.
4229 assert(worker_id < limit, "sanity");
4230 assert(!rp->discovery_is_atomic(), "check this code");
4231
4232 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4233 for (uint idx = worker_id; idx < limit; idx += stride) {
4234 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4235
4236 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4237 while (iter.has_next()) {
4238 // Since discovery is not atomic for the CM ref processor, we
4239 // can see some null referent objects.
4240 iter.load_ptrs(DEBUG_ONLY(true));
4241 oop ref = iter.obj();
4242
4243 // This will filter nulls.
4244 if (iter.is_referent_alive()) {
4245 iter.make_referent_alive();
4246 }
4247 iter.move_to_next();
4248 }
4249 }
4250
4251 // Drain the queue - which may cause stealing
4252 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4253 drain_queue.do_void();
4254 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4255 assert(pss->queue_is_empty(), "should be");
4256 }
4257 };
4258
4259 void G1CollectedHeap::process_weak_jni_handles() {
4260 double ref_proc_start = os::elapsedTime();
4261
4262 G1STWIsAliveClosure is_alive(this);
4263 G1KeepAliveClosure keep_alive(this);
4264 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4265
4266 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4267 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4268 }
4269
4270 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4271 // Any reference objects, in the collection set, that were 'discovered'
4272 // by the CM ref processor should have already been copied (either by
4273 // applying the external root copy closure to the discovered lists, or
4274 // by following an RSet entry).
4275 //
4276 // But some of the referents, that are in the collection set, that these
4277 // reference objects point to may not have been copied: the STW ref
4278 // processor would have seen that the reference object had already
4279 // been 'discovered' and would have skipped discovering the reference,
4280 // but would not have treated the reference object as a regular oop.
4281 // As a result the copy closure would not have been applied to the
4282 // referent object.
4283 //
4284 // We need to explicitly copy these referent objects - the references
4285 // will be processed at the end of remarking.
4286 //
4287 // We also need to do this copying before we process the reference
4288 // objects discovered by the STW ref processor in case one of these
4289 // referents points to another object which is also referenced by an
4290 // object discovered by the STW ref processor.
4291 double preserve_cm_referents_time = 0.0;
4292
4293 // To avoid spawning task when there is no work to do, check that
4294 // a concurrent cycle is active and that some references have been
4295 // discovered.
4296 if (concurrent_mark()->cmThread()->during_cycle() &&
4297 ref_processor_cm()->has_discovered_references()) {
4298 double preserve_cm_referents_start = os::elapsedTime();
4299 uint no_of_gc_workers = workers()->active_workers();
4300 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4301 per_thread_states,
4302 no_of_gc_workers,
4303 _task_queues);
4304 workers()->run_task(&keep_cm_referents);
4305 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4306 }
4307
4308 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4309 }
4310
4311 // Weak Reference processing during an evacuation pause (part 1).
4312 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4313 double ref_proc_start = os::elapsedTime();
4314
4315 ReferenceProcessor* rp = _ref_processor_stw;
4316 assert(rp->discovery_enabled(), "should have been enabled");
4317
4318 // Closure to test whether a referent is alive.
4319 G1STWIsAliveClosure is_alive(this);
4320
4321 // Even when parallel reference processing is enabled, the processing
4322 // of JNI refs is serial and performed serially by the current thread
4323 // rather than by a worker. The following PSS will be used for processing
4324 // JNI refs.
4325
4326 // Use only a single queue for this PSS.
4327 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4328 pss->set_ref_processor(NULL);
4329 assert(pss->queue_is_empty(), "pre-condition");
4330
4331 // Keep alive closure.
4332 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4333
4334 // Serial Complete GC closure
4335 G1STWDrainQueueClosure drain_queue(this, pss);
4336
4337 // Setup the soft refs policy...
4338 rp->setup_policy(false);
4339
4340 ReferenceProcessorStats stats;
4341 if (!rp->processing_is_mt()) {
4342 // Serial reference processing...
4343 stats = rp->process_discovered_references(&is_alive,
4344 &keep_alive,
4345 &drain_queue,
4346 NULL,
4347 _gc_timer_stw);
4348 } else {
4349 uint no_of_gc_workers = workers()->active_workers();
4350
4351 // Parallel reference processing
4352 assert(no_of_gc_workers <= rp->max_num_q(),
4353 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4354 no_of_gc_workers, rp->max_num_q());
4355
4356 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4357 stats = rp->process_discovered_references(&is_alive,
4358 &keep_alive,
4359 &drain_queue,
4360 &par_task_executor,
4361 _gc_timer_stw);
4362 }
4363
4364 _gc_tracer_stw->report_gc_reference_stats(stats);
4365
4366 // We have completed copying any necessary live referent objects.
4367 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4368
4369 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4370 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4371 }
4372
4373 // Weak Reference processing during an evacuation pause (part 2).
4374 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4375 double ref_enq_start = os::elapsedTime();
4376
4377 ReferenceProcessor* rp = _ref_processor_stw;
4378 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4379
4380 // Now enqueue any remaining on the discovered lists on to
4381 // the pending list.
4382 if (!rp->processing_is_mt()) {
4383 // Serial reference processing...
4384 rp->enqueue_discovered_references();
4385 } else {
4386 // Parallel reference enqueueing
4387
4388 uint n_workers = workers()->active_workers();
4389
4390 assert(n_workers <= rp->max_num_q(),
4391 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4392 n_workers, rp->max_num_q());
4393
4394 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4395 rp->enqueue_discovered_references(&par_task_executor);
4396 }
4397
4398 rp->verify_no_references_recorded();
4399 assert(!rp->discovery_enabled(), "should have been disabled");
4400
4401 // FIXME
4402 // CM's reference processing also cleans up the string and symbol tables.
4403 // Should we do that here also? We could, but it is a serial operation
4404 // and could significantly increase the pause time.
4405
4406 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4407 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4408 }
4409
4410 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4411 double merge_pss_time_start = os::elapsedTime();
4412 per_thread_states->flush();
4413 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4414 }
4415
4416 void G1CollectedHeap::pre_evacuate_collection_set() {
4417 _expand_heap_after_alloc_failure = true;
4418 _evacuation_failed = false;
4419
4420 // Disable the hot card cache.
4421 _hot_card_cache->reset_hot_cache_claimed_index();
4422 _hot_card_cache->set_use_cache(false);
4423
4424 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4425 _preserved_marks_set.assert_empty();
4426
4427 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4428
4429 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4430 if (collector_state()->during_initial_mark_pause()) {
4431 double start_clear_claimed_marks = os::elapsedTime();
4432
4433 ClassLoaderDataGraph::clear_claimed_marks();
4434
4435 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4436 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4437 }
4438 }
4439
4440 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4441 // Should G1EvacuationFailureALot be in effect for this GC?
4442 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4443
4444 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4445
4446 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4447
4448 double start_par_time_sec = os::elapsedTime();
4449 double end_par_time_sec;
4450
4451 {
4452 const uint n_workers = workers()->active_workers();
4453 G1RootProcessor root_processor(this, n_workers);
4454 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4455
4456 print_termination_stats_hdr();
4457
4458 workers()->run_task(&g1_par_task);
4459 end_par_time_sec = os::elapsedTime();
4460
4461 // Closing the inner scope will execute the destructor
4462 // for the G1RootProcessor object. We record the current
4463 // elapsed time before closing the scope so that time
4464 // taken for the destructor is NOT included in the
4465 // reported parallel time.
4466 }
4467
4468 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4469 phase_times->record_par_time(par_time_ms);
4470
4471 double code_root_fixup_time_ms =
4472 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4473 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4474 }
4475
4476 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4477 // Process any discovered reference objects - we have
4478 // to do this _before_ we retire the GC alloc regions
4479 // as we may have to copy some 'reachable' referent
4480 // objects (and their reachable sub-graphs) that were
4481 // not copied during the pause.
4482 if (g1_policy()->should_process_references()) {
4483 preserve_cm_referents(per_thread_states);
4484 process_discovered_references(per_thread_states);
4485 } else {
4486 ref_processor_stw()->verify_no_references_recorded();
4487 process_weak_jni_handles();
4488 }
4489
4490 if (G1StringDedup::is_enabled()) {
4491 double fixup_start = os::elapsedTime();
4492
4493 G1STWIsAliveClosure is_alive(this);
4494 G1KeepAliveClosure keep_alive(this);
4495 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4496
4497 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4498 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4499 }
4500
4501 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4502
4503 if (evacuation_failed()) {
4504 restore_after_evac_failure();
4505
4506 // Reset the G1EvacuationFailureALot counters and flags
4507 // Note: the values are reset only when an actual
4508 // evacuation failure occurs.
4509 NOT_PRODUCT(reset_evacuation_should_fail();)
4510 }
4511
4512 _preserved_marks_set.assert_empty();
4513
4514 // Enqueue any remaining references remaining on the STW
4515 // reference processor's discovered lists. We need to do
4516 // this after the card table is cleaned (and verified) as
4517 // the act of enqueueing entries on to the pending list
4518 // will log these updates (and dirty their associated
4519 // cards). We need these updates logged to update any
4520 // RSets.
4521 if (g1_policy()->should_process_references()) {
4522 enqueue_discovered_references(per_thread_states);
4523 } else {
4524 g1_policy()->phase_times()->record_ref_enq_time(0);
4525 }
4526
4527 _allocator->release_gc_alloc_regions(evacuation_info);
4528
4529 merge_per_thread_state_info(per_thread_states);
4530
4531 // Reset and re-enable the hot card cache.
4532 // Note the counts for the cards in the regions in the
4533 // collection set are reset when the collection set is freed.
4534 _hot_card_cache->reset_hot_cache();
4535 _hot_card_cache->set_use_cache(true);
4536
4537 purge_code_root_memory();
4538
4539 redirty_logged_cards();
4540 #if defined(COMPILER2) || INCLUDE_JVMCI
4541 double start = os::elapsedTime();
4542 DerivedPointerTable::update_pointers();
4543 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4544 #endif
4545 g1_policy()->print_age_table();
4546 }
4547
4548 void G1CollectedHeap::record_obj_copy_mem_stats() {
4549 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4550
4551 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4552 create_g1_evac_summary(&_old_evac_stats));
4553 }
4554
4555 void G1CollectedHeap::free_region(HeapRegion* hr,
4556 FreeRegionList* free_list,
4557 bool skip_remset,
4558 bool skip_hot_card_cache,
4559 bool locked) {
4560 assert(!hr->is_free(), "the region should not be free");
4561 assert(!hr->is_empty(), "the region should not be empty");
4562 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4563 assert(free_list != NULL, "pre-condition");
4564
4565 if (G1VerifyBitmaps) {
4566 MemRegion mr(hr->bottom(), hr->end());
4567 concurrent_mark()->clearRangePrevBitmap(mr);
4568 }
4569
4570 // Clear the card counts for this region.
4571 // Note: we only need to do this if the region is not young
4572 // (since we don't refine cards in young regions).
4573 if (!skip_hot_card_cache && !hr->is_young()) {
4574 _hot_card_cache->reset_card_counts(hr);
4575 }
4576 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4577 free_list->add_ordered(hr);
4578 }
4579
4580 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4581 FreeRegionList* free_list,
4582 bool skip_remset) {
4583 assert(hr->is_humongous(), "this is only for humongous regions");
4584 assert(free_list != NULL, "pre-condition");
4585 hr->clear_humongous();
4586 free_region(hr, free_list, skip_remset);
4587 }
4588
4589 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4590 const uint humongous_regions_removed) {
4591 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4592 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4593 _old_set.bulk_remove(old_regions_removed);
4594 _humongous_set.bulk_remove(humongous_regions_removed);
4595 }
4596
4597 }
4598
4599 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4600 assert(list != NULL, "list can't be null");
4601 if (!list->is_empty()) {
4602 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4603 _hrm.insert_list_into_free_list(list);
4604 }
4605 }
4606
4607 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4608 decrease_used(bytes);
4609 }
4610
4611 class G1ParScrubRemSetTask: public AbstractGangTask {
4612 protected:
4613 G1RemSet* _g1rs;
4614 HeapRegionClaimer _hrclaimer;
4615
4616 public:
4617 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4618 AbstractGangTask("G1 ScrubRS"),
4619 _g1rs(g1_rs),
4620 _hrclaimer(num_workers) {
4621 }
4622
4623 void work(uint worker_id) {
4624 _g1rs->scrub(worker_id, &_hrclaimer);
4625 }
4626 };
4627
4628 void G1CollectedHeap::scrub_rem_set() {
4629 uint num_workers = workers()->active_workers();
4630 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4631 workers()->run_task(&g1_par_scrub_rs_task);
4632 }
4633
4634 class G1FreeCollectionSetTask : public AbstractGangTask {
4635 private:
4636
4637 // Closure applied to all regions in the collection set to do work that needs to
4638 // be done serially in a single thread.
4639 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4640 private:
4641 EvacuationInfo* _evacuation_info;
4642 const size_t* _surviving_young_words;
4643
4644 // Bytes used in successfully evacuated regions before the evacuation.
4645 size_t _before_used_bytes;
4646 // Bytes used in unsucessfully evacuated regions before the evacuation
4647 size_t _after_used_bytes;
4648
4649 size_t _bytes_allocated_in_old_since_last_gc;
4650
4651 size_t _failure_used_words;
4652 size_t _failure_waste_words;
4653
4654 FreeRegionList _local_free_list;
4655 public:
4656 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4657 HeapRegionClosure(),
4658 _evacuation_info(evacuation_info),
4659 _surviving_young_words(surviving_young_words),
4660 _before_used_bytes(0),
4661 _after_used_bytes(0),
4662 _bytes_allocated_in_old_since_last_gc(0),
4663 _failure_used_words(0),
4664 _failure_waste_words(0),
4665 _local_free_list("Local Region List for CSet Freeing") {
4666 }
4667
4668 virtual bool doHeapRegion(HeapRegion* r) {
4669 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4670
4671 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4672 g1h->clear_in_cset(r);
4673
4674 if (r->is_young()) {
4675 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4676 "Young index %d is wrong for region %u of type %s with %u young regions",
4677 r->young_index_in_cset(),
4678 r->hrm_index(),
4679 r->get_type_str(),
4680 g1h->collection_set()->young_region_length());
4681 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4682 r->record_surv_words_in_group(words_survived);
4683 }
4684
4685 if (!r->evacuation_failed()) {
4686 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4687 _before_used_bytes += r->used();
4688 g1h->free_region(r,
4689 &_local_free_list,
4690 true, /* skip_remset */
4691 true, /* skip_hot_card_cache */
4692 true /* locked */);
4693 } else {
4694 r->uninstall_surv_rate_group();
4695 r->set_young_index_in_cset(-1);
4696 r->set_evacuation_failed(false);
4697 // When moving a young gen region to old gen, we "allocate" that whole region
4698 // there. This is in addition to any already evacuated objects. Notify the
4699 // policy about that.
4700 // Old gen regions do not cause an additional allocation: both the objects
4701 // still in the region and the ones already moved are accounted for elsewhere.
4702 if (r->is_young()) {
4703 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4704 }
4705 // The region is now considered to be old.
4706 r->set_old();
4707 // Do some allocation statistics accounting. Regions that failed evacuation
4708 // are always made old, so there is no need to update anything in the young
4709 // gen statistics, but we need to update old gen statistics.
4710 size_t used_words = r->marked_bytes() / HeapWordSize;
4711
4712 _failure_used_words += used_words;
4713 _failure_waste_words += HeapRegion::GrainWords - used_words;
4714
4715 g1h->old_set_add(r);
4716 _after_used_bytes += r->used();
4717 }
4718 return false;
4719 }
4720
4721 void complete_work() {
4722 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4723
4724 _evacuation_info->set_regions_freed(_local_free_list.length());
4725 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4726
4727 g1h->prepend_to_freelist(&_local_free_list);
4728 g1h->decrement_summary_bytes(_before_used_bytes);
4729
4730 G1Policy* policy = g1h->g1_policy();
4731 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4732
4733 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4734 }
4735 };
4736
4737 G1CollectionSet* _collection_set;
4738 G1SerialFreeCollectionSetClosure _cl;
4739 const size_t* _surviving_young_words;
4740
4741 size_t _rs_lengths;
4742
4743 volatile jint _serial_work_claim;
4744
4745 struct WorkItem {
4746 uint region_idx;
4747 bool is_young;
4748 bool evacuation_failed;
4749
4750 WorkItem(HeapRegion* r) {
4751 region_idx = r->hrm_index();
4752 is_young = r->is_young();
4753 evacuation_failed = r->evacuation_failed();
4754 }
4755 };
4756
4757 volatile size_t _parallel_work_claim;
4758 size_t _num_work_items;
4759 WorkItem* _work_items;
4760
4761 void do_serial_work() {
4762 // Need to grab the lock to be allowed to modify the old region list.
4763 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4764 _collection_set->iterate(&_cl);
4765 }
4766
4767 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4768 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4769
4770 HeapRegion* r = g1h->region_at(region_idx);
4771 assert(!g1h->is_on_master_free_list(r), "sanity");
4772
4773 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4774
4775 if (!is_young) {
4776 g1h->_hot_card_cache->reset_card_counts(r);
4777 }
4778
4779 if (!evacuation_failed) {
4780 r->rem_set()->clear_locked();
4781 }
4782 }
4783
4784 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4785 private:
4786 size_t _cur_idx;
4787 WorkItem* _work_items;
4788 public:
4789 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4790
4791 virtual bool doHeapRegion(HeapRegion* r) {
4792 _work_items[_cur_idx++] = WorkItem(r);
4793 return false;
4794 }
4795 };
4796
4797 void prepare_work() {
4798 G1PrepareFreeCollectionSetClosure cl(_work_items);
4799 _collection_set->iterate(&cl);
4800 }
4801
4802 void complete_work() {
4803 _cl.complete_work();
4804
4805 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4806 policy->record_max_rs_lengths(_rs_lengths);
4807 policy->cset_regions_freed();
4808 }
4809 public:
4810 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4811 AbstractGangTask("G1 Free Collection Set"),
4812 _cl(evacuation_info, surviving_young_words),
4813 _collection_set(collection_set),
4814 _surviving_young_words(surviving_young_words),
4815 _serial_work_claim(0),
4816 _rs_lengths(0),
4817 _parallel_work_claim(0),
4818 _num_work_items(collection_set->region_length()),
4819 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4820 prepare_work();
4821 }
4822
4823 ~G1FreeCollectionSetTask() {
4824 complete_work();
4825 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4826 }
4827
4828 // Chunk size for work distribution. The chosen value has been determined experimentally
4829 // to be a good tradeoff between overhead and achievable parallelism.
4830 static uint chunk_size() { return 32; }
4831
4832 virtual void work(uint worker_id) {
4833 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4834
4835 // Claim serial work.
4836 if (_serial_work_claim == 0) {
4837 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4838 if (value == 0) {
4839 double serial_time = os::elapsedTime();
4840 do_serial_work();
4841 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4842 }
4843 }
4844
4845 // Start parallel work.
4846 double young_time = 0.0;
4847 bool has_young_time = false;
4848 double non_young_time = 0.0;
4849 bool has_non_young_time = false;
4850
4851 while (true) {
4852 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4853 size_t cur = end - chunk_size();
4854
4855 if (cur >= _num_work_items) {
4856 break;
4857 }
4858
4859 double start_time = os::elapsedTime();
4860
4861 end = MIN2(end, _num_work_items);
4862
4863 for (; cur < end; cur++) {
4864 bool is_young = _work_items[cur].is_young;
4865
4866 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4867
4868 double end_time = os::elapsedTime();
4869 double time_taken = end_time - start_time;
4870 if (is_young) {
4871 young_time += time_taken;
4872 has_young_time = true;
4873 } else {
4874 non_young_time += time_taken;
4875 has_non_young_time = true;
4876 }
4877 start_time = end_time;
4878 }
4879 }
4880
4881 if (has_young_time) {
4882 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4883 }
4884 if (has_non_young_time) {
4885 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4886 }
4887 }
4888 };
4889
4890 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4891 _eden.clear();
4892
4893 double free_cset_start_time = os::elapsedTime();
4894
4895 {
4896 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4897 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4898
4899 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4900
4901 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4902 cl.name(),
4903 num_workers,
4904 _collection_set.region_length());
4905 workers()->run_task(&cl, num_workers);
4906 }
4907 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4908
4909 collection_set->clear();
4910 }
4911
4912 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4913 private:
4914 FreeRegionList* _free_region_list;
4915 HeapRegionSet* _proxy_set;
4916 uint _humongous_regions_removed;
4917 size_t _freed_bytes;
4918 public:
4919
4920 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4921 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4922 }
4923
4924 virtual bool doHeapRegion(HeapRegion* r) {
4925 if (!r->is_starts_humongous()) {
4926 return false;
4927 }
4928
4929 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4930
4931 oop obj = (oop)r->bottom();
4932 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4933
4934 // The following checks whether the humongous object is live are sufficient.
4935 // The main additional check (in addition to having a reference from the roots
4936 // or the young gen) is whether the humongous object has a remembered set entry.
4937 //
4938 // A humongous object cannot be live if there is no remembered set for it
4939 // because:
4940 // - there can be no references from within humongous starts regions referencing
4941 // the object because we never allocate other objects into them.
4942 // (I.e. there are no intra-region references that may be missed by the
4943 // remembered set)
4944 // - as soon there is a remembered set entry to the humongous starts region
4945 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4946 // until the end of a concurrent mark.
4947 //
4948 // It is not required to check whether the object has been found dead by marking
4949 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4950 // all objects allocated during that time are considered live.
4951 // SATB marking is even more conservative than the remembered set.
4952 // So if at this point in the collection there is no remembered set entry,
4953 // nobody has a reference to it.
4954 // At the start of collection we flush all refinement logs, and remembered sets
4955 // are completely up-to-date wrt to references to the humongous object.
4956 //
4957 // Other implementation considerations:
4958 // - never consider object arrays at this time because they would pose
4959 // considerable effort for cleaning up the the remembered sets. This is
4960 // required because stale remembered sets might reference locations that
4961 // are currently allocated into.
4962 uint region_idx = r->hrm_index();
4963 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4964 !r->rem_set()->is_empty()) {
4965 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",
4966 region_idx,
4967 (size_t)obj->size() * HeapWordSize,
4968 p2i(r->bottom()),
4969 r->rem_set()->occupied(),
4970 r->rem_set()->strong_code_roots_list_length(),
4971 next_bitmap->isMarked(r->bottom()),
4972 g1h->is_humongous_reclaim_candidate(region_idx),
4973 obj->is_typeArray()
4974 );
4975 return false;
4976 }
4977
4978 guarantee(obj->is_typeArray(),
4979 "Only eagerly reclaiming type arrays is supported, but the object "
4980 PTR_FORMAT " is not.", p2i(r->bottom()));
4981
4982 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",
4983 region_idx,
4984 (size_t)obj->size() * HeapWordSize,
4985 p2i(r->bottom()),
4986 r->rem_set()->occupied(),
4987 r->rem_set()->strong_code_roots_list_length(),
4988 next_bitmap->isMarked(r->bottom()),
4989 g1h->is_humongous_reclaim_candidate(region_idx),
4990 obj->is_typeArray()
4991 );
4992
4993 // Need to clear mark bit of the humongous object if already set.
4994 if (next_bitmap->isMarked(r->bottom())) {
4995 next_bitmap->clear(r->bottom());
4996 }
4997 do {
4998 HeapRegion* next = g1h->next_region_in_humongous(r);
4999 _freed_bytes += r->used();
5000 r->set_containing_set(NULL);
5001 _humongous_regions_removed++;
5002 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
5003 r = next;
5004 } while (r != NULL);
5005
5006 return false;
5007 }
5008
5009 uint humongous_free_count() {
5010 return _humongous_regions_removed;
5011 }
5012
5013 size_t bytes_freed() const {
5014 return _freed_bytes;
5015 }
5016 };
5017
5018 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5019 assert_at_safepoint(true);
5020
5021 if (!G1EagerReclaimHumongousObjects ||
5022 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5023 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5024 return;
5025 }
5026
5027 double start_time = os::elapsedTime();
5028
5029 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5030
5031 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5032 heap_region_iterate(&cl);
5033
5034 remove_from_old_sets(0, cl.humongous_free_count());
5035
5036 G1HRPrinter* hrp = hr_printer();
5037 if (hrp->is_active()) {
5038 FreeRegionListIterator iter(&local_cleanup_list);
5039 while (iter.more_available()) {
5040 HeapRegion* hr = iter.get_next();
5041 hrp->cleanup(hr);
5042 }
5043 }
5044
5045 prepend_to_freelist(&local_cleanup_list);
5046 decrement_summary_bytes(cl.bytes_freed());
5047
5048 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5049 cl.humongous_free_count());
5050 }
5051
5052 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5053 public:
5054 virtual bool doHeapRegion(HeapRegion* r) {
5055 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5056 G1CollectedHeap::heap()->clear_in_cset(r);
5057 r->set_young_index_in_cset(-1);
5058 return false;
5059 }
5060 };
5061
5062 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5063 G1AbandonCollectionSetClosure cl;
5064 collection_set->iterate(&cl);
5065
5066 collection_set->clear();
5067 collection_set->stop_incremental_building();
5068 }
5069
5070 void G1CollectedHeap::set_free_regions_coming() {
5071 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5072
5073 assert(!free_regions_coming(), "pre-condition");
5074 _free_regions_coming = true;
5075 }
5076
5077 void G1CollectedHeap::reset_free_regions_coming() {
5078 assert(free_regions_coming(), "pre-condition");
5079
5080 {
5081 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5082 _free_regions_coming = false;
5083 SecondaryFreeList_lock->notify_all();
5084 }
5085
5086 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5087 }
5088
5089 void G1CollectedHeap::wait_while_free_regions_coming() {
5090 // Most of the time we won't have to wait, so let's do a quick test
5091 // first before we take the lock.
5092 if (!free_regions_coming()) {
5093 return;
5094 }
5095
5096 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5097
5098 {
5099 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5100 while (free_regions_coming()) {
5101 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5102 }
5103 }
5104
5105 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5106 }
5107
5108 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5109 return _allocator->is_retained_old_region(hr);
5110 }
5111
5112 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5113 _eden.add(hr);
5114 _g1_policy->set_region_eden(hr);
5115 }
5116
5117 #ifdef ASSERT
5118
5119 class NoYoungRegionsClosure: public HeapRegionClosure {
5120 private:
5121 bool _success;
5122 public:
5123 NoYoungRegionsClosure() : _success(true) { }
5124 bool doHeapRegion(HeapRegion* r) {
5125 if (r->is_young()) {
5126 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5127 p2i(r->bottom()), p2i(r->end()));
5128 _success = false;
5129 }
5130 return false;
5131 }
5132 bool success() { return _success; }
5133 };
5134
5135 bool G1CollectedHeap::check_young_list_empty() {
5136 bool ret = (young_regions_count() == 0);
5137
5138 NoYoungRegionsClosure closure;
5139 heap_region_iterate(&closure);
5140 ret = ret && closure.success();
5141
5142 return ret;
5143 }
5144
5145 #endif // ASSERT
5146
5147 class TearDownRegionSetsClosure : public HeapRegionClosure {
5148 private:
5149 HeapRegionSet *_old_set;
5150
5151 public:
5152 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5153
5154 bool doHeapRegion(HeapRegion* r) {
5155 if (r->is_old()) {
5156 _old_set->remove(r);
5157 } else if(r->is_young()) {
5158 r->uninstall_surv_rate_group();
5159 } else {
5160 // We ignore free regions, we'll empty the free list afterwards.
5161 // We ignore humongous regions, we're not tearing down the
5162 // humongous regions set.
5163 assert(r->is_free() || r->is_humongous(),
5164 "it cannot be another type");
5165 }
5166 return false;
5167 }
5168
5169 ~TearDownRegionSetsClosure() {
5170 assert(_old_set->is_empty(), "post-condition");
5171 }
5172 };
5173
5174 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5175 assert_at_safepoint(true /* should_be_vm_thread */);
5176
5177 if (!free_list_only) {
5178 TearDownRegionSetsClosure cl(&_old_set);
5179 heap_region_iterate(&cl);
5180
5181 // Note that emptying the _young_list is postponed and instead done as
5182 // the first step when rebuilding the regions sets again. The reason for
5183 // this is that during a full GC string deduplication needs to know if
5184 // a collected region was young or old when the full GC was initiated.
5185 }
5186 _hrm.remove_all_free_regions();
5187 }
5188
5189 void G1CollectedHeap::increase_used(size_t bytes) {
5190 _summary_bytes_used += bytes;
5191 }
5192
5193 void G1CollectedHeap::decrease_used(size_t bytes) {
5194 assert(_summary_bytes_used >= bytes,
5195 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5196 _summary_bytes_used, bytes);
5197 _summary_bytes_used -= bytes;
5198 }
5199
5200 void G1CollectedHeap::set_used(size_t bytes) {
5201 _summary_bytes_used = bytes;
5202 }
5203
5204 class RebuildRegionSetsClosure : public HeapRegionClosure {
5205 private:
5206 bool _free_list_only;
5207 HeapRegionSet* _old_set;
5208 HeapRegionManager* _hrm;
5209 size_t _total_used;
5210
5211 public:
5212 RebuildRegionSetsClosure(bool free_list_only,
5213 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5214 _free_list_only(free_list_only),
5215 _old_set(old_set), _hrm(hrm), _total_used(0) {
5216 assert(_hrm->num_free_regions() == 0, "pre-condition");
5217 if (!free_list_only) {
5218 assert(_old_set->is_empty(), "pre-condition");
5219 }
5220 }
5221
5222 bool doHeapRegion(HeapRegion* r) {
5223 if (r->is_empty()) {
5224 // Add free regions to the free list
5225 r->set_free();
5226 r->set_allocation_context(AllocationContext::system());
5227 _hrm->insert_into_free_list(r);
5228 } else if (!_free_list_only) {
5229
5230 if (r->is_humongous()) {
5231 // We ignore humongous regions. We left the humongous set unchanged.
5232 } else {
5233 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5234 // We now consider all regions old, so register as such. Leave
5235 // archive regions set that way, however, while still adding
5236 // them to the old set.
5237 if (!r->is_archive()) {
5238 r->set_old();
5239 }
5240 _old_set->add(r);
5241 }
5242 _total_used += r->used();
5243 }
5244
5245 return false;
5246 }
5247
5248 size_t total_used() {
5249 return _total_used;
5250 }
5251 };
5252
5253 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5254 assert_at_safepoint(true /* should_be_vm_thread */);
5255
5256 if (!free_list_only) {
5257 _eden.clear();
5258 _survivor.clear();
5259 }
5260
5261 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5262 heap_region_iterate(&cl);
5263
5264 if (!free_list_only) {
5265 set_used(cl.total_used());
5266 if (_archive_allocator != NULL) {
5267 _archive_allocator->clear_used();
5268 }
5269 }
5270 assert(used_unlocked() == recalculate_used(),
5271 "inconsistent used_unlocked(), "
5272 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5273 used_unlocked(), recalculate_used());
5274 }
5275
5276 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5277 _refine_cte_cl->set_concurrent(concurrent);
5278 }
5279
5280 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5281 HeapRegion* hr = heap_region_containing(p);
5282 return hr->is_in(p);
5283 }
5284
5285 // Methods for the mutator alloc region
5286
5287 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5288 bool force) {
5289 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5290 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5291 if (force || should_allocate) {
5292 HeapRegion* new_alloc_region = new_region(word_size,
5293 false /* is_old */,
5294 false /* do_expand */);
5295 if (new_alloc_region != NULL) {
5296 set_region_short_lived_locked(new_alloc_region);
5297 _hr_printer.alloc(new_alloc_region, !should_allocate);
5298 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5299 return new_alloc_region;
5300 }
5301 }
5302 return NULL;
5303 }
5304
5305 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5306 size_t allocated_bytes) {
5307 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5308 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5309
5310 collection_set()->add_eden_region(alloc_region);
5311 increase_used(allocated_bytes);
5312 _hr_printer.retire(alloc_region);
5313 // We update the eden sizes here, when the region is retired,
5314 // instead of when it's allocated, since this is the point that its
5315 // used space has been recored in _summary_bytes_used.
5316 g1mm()->update_eden_size();
5317 }
5318
5319 // Methods for the GC alloc regions
5320
5321 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5322 if (dest.is_old()) {
5323 return true;
5324 } else {
5325 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5326 }
5327 }
5328
5329 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5330 assert(FreeList_lock->owned_by_self(), "pre-condition");
5331
5332 if (!has_more_regions(dest)) {
5333 return NULL;
5334 }
5335
5336 const bool is_survivor = dest.is_young();
5337
5338 HeapRegion* new_alloc_region = new_region(word_size,
5339 !is_survivor,
5340 true /* do_expand */);
5341 if (new_alloc_region != NULL) {
5342 // We really only need to do this for old regions given that we
5343 // should never scan survivors. But it doesn't hurt to do it
5344 // for survivors too.
5345 new_alloc_region->record_timestamp();
5346 if (is_survivor) {
5347 new_alloc_region->set_survivor();
5348 _survivor.add(new_alloc_region);
5349 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5350 } else {
5351 new_alloc_region->set_old();
5352 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5353 }
5354 _hr_printer.alloc(new_alloc_region);
5355 bool during_im = collector_state()->during_initial_mark_pause();
5356 new_alloc_region->note_start_of_copying(during_im);
5357 return new_alloc_region;
5358 }
5359 return NULL;
5360 }
5361
5362 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5363 size_t allocated_bytes,
5364 InCSetState dest) {
5365 bool during_im = collector_state()->during_initial_mark_pause();
5366 alloc_region->note_end_of_copying(during_im);
5367 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5368 if (dest.is_old()) {
5369 _old_set.add(alloc_region);
5370 }
5371 _hr_printer.retire(alloc_region);
5372 }
5373
5374 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5375 bool expanded = false;
5376 uint index = _hrm.find_highest_free(&expanded);
5377
5378 if (index != G1_NO_HRM_INDEX) {
5379 if (expanded) {
5380 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5381 HeapRegion::GrainWords * HeapWordSize);
5382 }
5383 _hrm.allocate_free_regions_starting_at(index, 1);
5384 return region_at(index);
5385 }
5386 return NULL;
5387 }
5388
5389 // Optimized nmethod scanning
5390
5391 class RegisterNMethodOopClosure: public OopClosure {
5392 G1CollectedHeap* _g1h;
5393 nmethod* _nm;
5394
5395 template <class T> void do_oop_work(T* p) {
5396 T heap_oop = oopDesc::load_heap_oop(p);
5397 if (!oopDesc::is_null(heap_oop)) {
5398 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5399 HeapRegion* hr = _g1h->heap_region_containing(obj);
5400 assert(!hr->is_continues_humongous(),
5401 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5402 " starting at " HR_FORMAT,
5403 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5404
5405 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5406 hr->add_strong_code_root_locked(_nm);
5407 }
5408 }
5409
5410 public:
5411 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5412 _g1h(g1h), _nm(nm) {}
5413
5414 void do_oop(oop* p) { do_oop_work(p); }
5415 void do_oop(narrowOop* p) { do_oop_work(p); }
5416 };
5417
5418 class UnregisterNMethodOopClosure: public OopClosure {
5419 G1CollectedHeap* _g1h;
5420 nmethod* _nm;
5421
5422 template <class T> void do_oop_work(T* p) {
5423 T heap_oop = oopDesc::load_heap_oop(p);
5424 if (!oopDesc::is_null(heap_oop)) {
5425 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5426 HeapRegion* hr = _g1h->heap_region_containing(obj);
5427 assert(!hr->is_continues_humongous(),
5428 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5429 " starting at " HR_FORMAT,
5430 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5431
5432 hr->remove_strong_code_root(_nm);
5433 }
5434 }
5435
5436 public:
5437 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5438 _g1h(g1h), _nm(nm) {}
5439
5440 void do_oop(oop* p) { do_oop_work(p); }
5441 void do_oop(narrowOop* p) { do_oop_work(p); }
5442 };
5443
5444 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5445 CollectedHeap::register_nmethod(nm);
5446
5447 guarantee(nm != NULL, "sanity");
5448 RegisterNMethodOopClosure reg_cl(this, nm);
5449 nm->oops_do(®_cl);
5450 }
5451
5452 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5453 CollectedHeap::unregister_nmethod(nm);
5454
5455 guarantee(nm != NULL, "sanity");
5456 UnregisterNMethodOopClosure reg_cl(this, nm);
5457 nm->oops_do(®_cl, true);
5458 }
5459
5460 void G1CollectedHeap::purge_code_root_memory() {
5461 double purge_start = os::elapsedTime();
5462 G1CodeRootSet::purge();
5463 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5464 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5465 }
5466
5467 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5468 G1CollectedHeap* _g1h;
5469
5470 public:
5471 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5472 _g1h(g1h) {}
5473
5474 void do_code_blob(CodeBlob* cb) {
5475 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5476 if (nm == NULL) {
5477 return;
5478 }
5479
5480 if (ScavengeRootsInCode) {
5481 _g1h->register_nmethod(nm);
5482 }
5483 }
5484 };
5485
5486 void G1CollectedHeap::rebuild_strong_code_roots() {
5487 RebuildStrongCodeRootClosure blob_cl(this);
5488 CodeCache::blobs_do(&blob_cl);
5489 }