1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/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 // How many words we use for filler objects.
304 size_t word_fill_size = word_size_sum - word_size;
305
306 // How many words memory we "waste" which cannot hold a filler object.
307 size_t words_not_fillable = 0;
308
309 if (word_fill_size >= min_fill_size()) {
310 fill_with_objects(obj_top, word_fill_size);
311 } else if (word_fill_size > 0) {
312 // We have space to fill, but we cannot fit an object there.
313 words_not_fillable = word_fill_size;
314 word_fill_size = 0;
315 }
316
317 // We will set up the first region as "starts humongous". This
318 // will also update the BOT covering all the regions to reflect
319 // that there is a single object that starts at the bottom of the
320 // first region.
321 first_hr->set_starts_humongous(obj_top, word_fill_size);
322 first_hr->set_allocation_context(context);
323 // Then, if there are any, we will set up the "continues
324 // humongous" regions.
325 HeapRegion* hr = NULL;
326 for (uint i = first + 1; i <= last; ++i) {
327 hr = region_at(i);
328 hr->set_continues_humongous(first_hr);
329 hr->set_allocation_context(context);
330 }
331
332 // Up to this point no concurrent thread would have been able to
333 // do any scanning on any region in this series. All the top
334 // fields still point to bottom, so the intersection between
335 // [bottom,top] and [card_start,card_end] will be empty. Before we
336 // update the top fields, we'll do a storestore to make sure that
337 // no thread sees the update to top before the zeroing of the
338 // object header and the BOT initialization.
339 OrderAccess::storestore();
340
341 // Now, we will update the top fields of the "continues humongous"
342 // regions except the last one.
343 for (uint i = first; i < last; ++i) {
344 hr = region_at(i);
345 hr->set_top(hr->end());
346 }
347
348 hr = region_at(last);
349 // If we cannot fit a filler object, we must set top to the end
350 // of the humongous object, otherwise we cannot iterate the heap
351 // and the BOT will not be complete.
352 hr->set_top(hr->end() - words_not_fillable);
353
354 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
355 "obj_top should be in last region");
356
357 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
358
359 assert(words_not_fillable == 0 ||
360 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
361 "Miscalculation in humongous allocation");
362
363 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
364
365 for (uint i = first; i <= last; ++i) {
366 hr = region_at(i);
367 _humongous_set.add(hr);
368 _hr_printer.alloc(hr);
369 }
370
371 return new_obj;
372 }
373
374 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
375 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
376 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
377 }
378
379 // If could fit into free regions w/o expansion, try.
380 // Otherwise, if can expand, do so.
381 // Otherwise, if using ex regions might help, try with ex given back.
382 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
383 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
384
385 _verifier->verify_region_sets_optional();
386
387 uint first = G1_NO_HRM_INDEX;
388 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
389
390 if (obj_regions == 1) {
391 // Only one region to allocate, try to use a fast path by directly allocating
392 // from the free lists. Do not try to expand here, we will potentially do that
393 // later.
394 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
395 if (hr != NULL) {
396 first = hr->hrm_index();
397 }
398 } else {
399 // We can't allocate humongous regions spanning more than one region while
400 // cleanupComplete() is running, since some of the regions we find to be
401 // empty might not yet be added to the free list. It is not straightforward
402 // to know in which list they are on so that we can remove them. We only
403 // need to do this if we need to allocate more than one region to satisfy the
404 // current humongous allocation request. If we are only allocating one region
405 // we use the one-region region allocation code (see above), that already
406 // potentially waits for regions from the secondary free list.
407 wait_while_free_regions_coming();
408 append_secondary_free_list_if_not_empty_with_lock();
409
410 // Policy: Try only empty regions (i.e. already committed first). Maybe we
411 // are lucky enough to find some.
412 first = _hrm.find_contiguous_only_empty(obj_regions);
413 if (first != G1_NO_HRM_INDEX) {
414 _hrm.allocate_free_regions_starting_at(first, obj_regions);
415 }
416 }
417
418 if (first == G1_NO_HRM_INDEX) {
419 // Policy: We could not find enough regions for the humongous object in the
420 // free list. Look through the heap to find a mix of free and uncommitted regions.
421 // If so, try expansion.
422 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
423 if (first != G1_NO_HRM_INDEX) {
424 // We found something. Make sure these regions are committed, i.e. expand
425 // the heap. Alternatively we could do a defragmentation GC.
426 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
427 word_size * HeapWordSize);
428
429 _hrm.expand_at(first, obj_regions, workers());
430 g1_policy()->record_new_heap_size(num_regions());
431
432 #ifdef ASSERT
433 for (uint i = first; i < first + obj_regions; ++i) {
434 HeapRegion* hr = region_at(i);
435 assert(hr->is_free(), "sanity");
436 assert(hr->is_empty(), "sanity");
437 assert(is_on_master_free_list(hr), "sanity");
438 }
439 #endif
440 _hrm.allocate_free_regions_starting_at(first, obj_regions);
441 } else {
442 // Policy: Potentially trigger a defragmentation GC.
443 }
444 }
445
446 HeapWord* result = NULL;
447 if (first != G1_NO_HRM_INDEX) {
448 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
449 word_size, context);
450 assert(result != NULL, "it should always return a valid result");
451
452 // A successful humongous object allocation changes the used space
453 // information of the old generation so we need to recalculate the
454 // sizes and update the jstat counters here.
455 g1mm()->update_sizes();
456 }
457
458 _verifier->verify_region_sets_optional();
459
460 return result;
461 }
462
463 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
464 assert_heap_not_locked_and_not_at_safepoint();
465 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
466
467 uint dummy_gc_count_before;
468 uint dummy_gclocker_retry_count = 0;
469 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
470 }
471
472 HeapWord*
473 G1CollectedHeap::mem_allocate(size_t word_size,
474 bool* gc_overhead_limit_was_exceeded) {
475 assert_heap_not_locked_and_not_at_safepoint();
476
477 // Loop until the allocation is satisfied, or unsatisfied after GC.
478 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
479 uint gc_count_before;
480
481 HeapWord* result = NULL;
482 if (!is_humongous(word_size)) {
483 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
484 } else {
485 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
486 }
487 if (result != NULL) {
488 return result;
489 }
490
491 // Create the garbage collection operation...
492 VM_G1CollectForAllocation op(gc_count_before, word_size);
493 op.set_allocation_context(AllocationContext::current());
494
495 // ...and get the VM thread to execute it.
496 VMThread::execute(&op);
497
498 if (op.prologue_succeeded() && op.pause_succeeded()) {
499 // If the operation was successful we'll return the result even
500 // if it is NULL. If the allocation attempt failed immediately
501 // after a Full GC, it's unlikely we'll be able to allocate now.
502 HeapWord* result = op.result();
503 if (result != NULL && !is_humongous(word_size)) {
504 // Allocations that take place on VM operations do not do any
505 // card dirtying and we have to do it here. We only have to do
506 // this for non-humongous allocations, though.
507 dirty_young_block(result, word_size);
508 }
509 return result;
510 } else {
511 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
512 return NULL;
513 }
514 assert(op.result() == NULL,
515 "the result should be NULL if the VM op did not succeed");
516 }
517
518 // Give a warning if we seem to be looping forever.
519 if ((QueuedAllocationWarningCount > 0) &&
520 (try_count % QueuedAllocationWarningCount == 0)) {
521 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
522 }
523 }
524
525 ShouldNotReachHere();
526 return NULL;
527 }
528
529 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
530 AllocationContext_t context,
531 uint* gc_count_before_ret,
532 uint* gclocker_retry_count_ret) {
533 // Make sure you read the note in attempt_allocation_humongous().
534
535 assert_heap_not_locked_and_not_at_safepoint();
536 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
537 "be called for humongous allocation requests");
538
539 // We should only get here after the first-level allocation attempt
540 // (attempt_allocation()) failed to allocate.
541
542 // We will loop until a) we manage to successfully perform the
543 // allocation or b) we successfully schedule a collection which
544 // fails to perform the allocation. b) is the only case when we'll
545 // return NULL.
546 HeapWord* result = NULL;
547 for (int try_count = 1; /* we'll return */; try_count += 1) {
548 bool should_try_gc;
549 uint gc_count_before;
550
551 {
552 MutexLockerEx x(Heap_lock);
553 result = _allocator->attempt_allocation_locked(word_size, context);
554 if (result != NULL) {
555 return result;
556 }
557
558 if (GCLocker::is_active_and_needs_gc()) {
559 if (g1_policy()->can_expand_young_list()) {
560 // No need for an ergo verbose message here,
561 // can_expand_young_list() does this when it returns true.
562 result = _allocator->attempt_allocation_force(word_size, context);
563 if (result != NULL) {
564 return result;
565 }
566 }
567 should_try_gc = false;
568 } else {
569 // The GCLocker may not be active but the GCLocker initiated
570 // GC may not yet have been performed (GCLocker::needs_gc()
571 // returns true). In this case we do not try this GC and
572 // wait until the GCLocker initiated GC is performed, and
573 // then retry the allocation.
574 if (GCLocker::needs_gc()) {
575 should_try_gc = false;
576 } else {
577 // Read the GC count while still holding the Heap_lock.
578 gc_count_before = total_collections();
579 should_try_gc = true;
580 }
581 }
582 }
583
584 if (should_try_gc) {
585 bool succeeded;
586 result = do_collection_pause(word_size, gc_count_before, &succeeded,
587 GCCause::_g1_inc_collection_pause);
588 if (result != NULL) {
589 assert(succeeded, "only way to get back a non-NULL result");
590 return result;
591 }
592
593 if (succeeded) {
594 // If we get here we successfully scheduled a collection which
595 // failed to allocate. No point in trying to allocate
596 // further. We'll just return NULL.
597 MutexLockerEx x(Heap_lock);
598 *gc_count_before_ret = total_collections();
599 return NULL;
600 }
601 } else {
602 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
603 MutexLockerEx x(Heap_lock);
604 *gc_count_before_ret = total_collections();
605 return NULL;
606 }
607 // The GCLocker is either active or the GCLocker initiated
608 // GC has not yet been performed. Stall until it is and
609 // then retry the allocation.
610 GCLocker::stall_until_clear();
611 (*gclocker_retry_count_ret) += 1;
612 }
613
614 // We can reach here if we were unsuccessful in scheduling a
615 // collection (because another thread beat us to it) or if we were
616 // stalled due to the GC locker. In either can we should retry the
617 // allocation attempt in case another thread successfully
618 // performed a collection and reclaimed enough space. We do the
619 // first attempt (without holding the Heap_lock) here and the
620 // follow-on attempt will be at the start of the next loop
621 // iteration (after taking the Heap_lock).
622 result = _allocator->attempt_allocation(word_size, context);
623 if (result != NULL) {
624 return result;
625 }
626
627 // Give a warning if we seem to be looping forever.
628 if ((QueuedAllocationWarningCount > 0) &&
629 (try_count % QueuedAllocationWarningCount == 0)) {
630 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
631 "retries %d times", try_count);
632 }
633 }
634
635 ShouldNotReachHere();
636 return NULL;
637 }
638
639 void G1CollectedHeap::begin_archive_alloc_range() {
640 assert_at_safepoint(true /* should_be_vm_thread */);
641 if (_archive_allocator == NULL) {
642 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
643 }
644 }
645
646 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
647 // Allocations in archive regions cannot be of a size that would be considered
648 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
649 // may be different at archive-restore time.
650 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
651 }
652
653 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
654 assert_at_safepoint(true /* should_be_vm_thread */);
655 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
656 if (is_archive_alloc_too_large(word_size)) {
657 return NULL;
658 }
659 return _archive_allocator->archive_mem_allocate(word_size);
660 }
661
662 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
663 size_t end_alignment_in_bytes) {
664 assert_at_safepoint(true /* should_be_vm_thread */);
665 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
666
667 // Call complete_archive to do the real work, filling in the MemRegion
668 // array with the archive regions.
669 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
670 delete _archive_allocator;
671 _archive_allocator = NULL;
672 }
673
674 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
675 assert(ranges != NULL, "MemRegion array NULL");
676 assert(count != 0, "No MemRegions provided");
677 MemRegion reserved = _hrm.reserved();
678 for (size_t i = 0; i < count; i++) {
679 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
680 return false;
681 }
682 }
683 return true;
684 }
685
686 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
687 assert(!is_init_completed(), "Expect to be called at JVM init time");
688 assert(ranges != NULL, "MemRegion array NULL");
689 assert(count != 0, "No MemRegions provided");
690 MutexLockerEx x(Heap_lock);
691
692 MemRegion reserved = _hrm.reserved();
693 HeapWord* prev_last_addr = NULL;
694 HeapRegion* prev_last_region = NULL;
695
696 // Temporarily disable pretouching of heap pages. This interface is used
697 // when mmap'ing archived heap data in, so pre-touching is wasted.
698 FlagSetting fs(AlwaysPreTouch, false);
699
700 // Enable archive object checking in G1MarkSweep. We have to let it know
701 // about each archive range, so that objects in those ranges aren't marked.
702 G1MarkSweep::enable_archive_object_check();
703
704 // For each specified MemRegion range, allocate the corresponding G1
705 // regions and mark them as archive regions. We expect the ranges in
706 // ascending starting address order, without overlap.
707 for (size_t i = 0; i < count; i++) {
708 MemRegion curr_range = ranges[i];
709 HeapWord* start_address = curr_range.start();
710 size_t word_size = curr_range.word_size();
711 HeapWord* last_address = curr_range.last();
712 size_t commits = 0;
713
714 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
715 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
716 p2i(start_address), p2i(last_address));
717 guarantee(start_address > prev_last_addr,
718 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
719 p2i(start_address), p2i(prev_last_addr));
720 prev_last_addr = last_address;
721
722 // Check for ranges that start in the same G1 region in which the previous
723 // range ended, and adjust the start address so we don't try to allocate
724 // the same region again. If the current range is entirely within that
725 // region, skip it, just adjusting the recorded top.
726 HeapRegion* start_region = _hrm.addr_to_region(start_address);
727 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
728 start_address = start_region->end();
729 if (start_address > last_address) {
730 increase_used(word_size * HeapWordSize);
731 start_region->set_top(last_address + 1);
732 continue;
733 }
734 start_region->set_top(start_address);
735 curr_range = MemRegion(start_address, last_address + 1);
736 start_region = _hrm.addr_to_region(start_address);
737 }
738
739 // Perform the actual region allocation, exiting if it fails.
740 // Then note how much new space we have allocated.
741 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
742 return false;
743 }
744 increase_used(word_size * HeapWordSize);
745 if (commits != 0) {
746 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
747 HeapRegion::GrainWords * HeapWordSize * commits);
748
749 }
750
751 // Mark each G1 region touched by the range as archive, add it to the old set,
752 // and set the allocation context and top.
753 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
754 HeapRegion* last_region = _hrm.addr_to_region(last_address);
755 prev_last_region = last_region;
756
757 while (curr_region != NULL) {
758 assert(curr_region->is_empty() && !curr_region->is_pinned(),
759 "Region already in use (index %u)", curr_region->hrm_index());
760 curr_region->set_allocation_context(AllocationContext::system());
761 curr_region->set_archive();
762 _hr_printer.alloc(curr_region);
763 _old_set.add(curr_region);
764 if (curr_region != last_region) {
765 curr_region->set_top(curr_region->end());
766 curr_region = _hrm.next_region_in_heap(curr_region);
767 } else {
768 curr_region->set_top(last_address + 1);
769 curr_region = NULL;
770 }
771 }
772
773 // Notify mark-sweep of the archive range.
774 G1MarkSweep::set_range_archive(curr_range, true);
775 }
776 return true;
777 }
778
779 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
780 assert(!is_init_completed(), "Expect to be called at JVM init time");
781 assert(ranges != NULL, "MemRegion array NULL");
782 assert(count != 0, "No MemRegions provided");
783 MemRegion reserved = _hrm.reserved();
784 HeapWord *prev_last_addr = NULL;
785 HeapRegion* prev_last_region = NULL;
786
787 // For each MemRegion, create filler objects, if needed, in the G1 regions
788 // that contain the address range. The address range actually within the
789 // MemRegion will not be modified. That is assumed to have been initialized
790 // elsewhere, probably via an mmap of archived heap data.
791 MutexLockerEx x(Heap_lock);
792 for (size_t i = 0; i < count; i++) {
793 HeapWord* start_address = ranges[i].start();
794 HeapWord* last_address = ranges[i].last();
795
796 assert(reserved.contains(start_address) && reserved.contains(last_address),
797 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
798 p2i(start_address), p2i(last_address));
799 assert(start_address > prev_last_addr,
800 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
801 p2i(start_address), p2i(prev_last_addr));
802
803 HeapRegion* start_region = _hrm.addr_to_region(start_address);
804 HeapRegion* last_region = _hrm.addr_to_region(last_address);
805 HeapWord* bottom_address = start_region->bottom();
806
807 // Check for a range beginning in the same region in which the
808 // previous one ended.
809 if (start_region == prev_last_region) {
810 bottom_address = prev_last_addr + 1;
811 }
812
813 // Verify that the regions were all marked as archive regions by
814 // alloc_archive_regions.
815 HeapRegion* curr_region = start_region;
816 while (curr_region != NULL) {
817 guarantee(curr_region->is_archive(),
818 "Expected archive region at index %u", curr_region->hrm_index());
819 if (curr_region != last_region) {
820 curr_region = _hrm.next_region_in_heap(curr_region);
821 } else {
822 curr_region = NULL;
823 }
824 }
825
826 prev_last_addr = last_address;
827 prev_last_region = last_region;
828
829 // Fill the memory below the allocated range with dummy object(s),
830 // if the region bottom does not match the range start, or if the previous
831 // range ended within the same G1 region, and there is a gap.
832 if (start_address != bottom_address) {
833 size_t fill_size = pointer_delta(start_address, bottom_address);
834 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
835 increase_used(fill_size * HeapWordSize);
836 }
837 }
838 }
839
840 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
841 uint* gc_count_before_ret,
842 uint* gclocker_retry_count_ret) {
843 assert_heap_not_locked_and_not_at_safepoint();
844 assert(!is_humongous(word_size), "attempt_allocation() should not "
845 "be called for humongous allocation requests");
846
847 AllocationContext_t context = AllocationContext::current();
848 HeapWord* result = _allocator->attempt_allocation(word_size, context);
849
850 if (result == NULL) {
851 result = attempt_allocation_slow(word_size,
852 context,
853 gc_count_before_ret,
854 gclocker_retry_count_ret);
855 }
856 assert_heap_not_locked();
857 if (result != NULL) {
858 dirty_young_block(result, word_size);
859 }
860 return result;
861 }
862
863 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
864 assert(!is_init_completed(), "Expect to be called at JVM init time");
865 assert(ranges != NULL, "MemRegion array NULL");
866 assert(count != 0, "No MemRegions provided");
867 MemRegion reserved = _hrm.reserved();
868 HeapWord* prev_last_addr = NULL;
869 HeapRegion* prev_last_region = NULL;
870 size_t size_used = 0;
871 size_t uncommitted_regions = 0;
872
873 // For each Memregion, free the G1 regions that constitute it, and
874 // notify mark-sweep that the range is no longer to be considered 'archive.'
875 MutexLockerEx x(Heap_lock);
876 for (size_t i = 0; i < count; i++) {
877 HeapWord* start_address = ranges[i].start();
878 HeapWord* last_address = ranges[i].last();
879
880 assert(reserved.contains(start_address) && reserved.contains(last_address),
881 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
882 p2i(start_address), p2i(last_address));
883 assert(start_address > prev_last_addr,
884 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
885 p2i(start_address), p2i(prev_last_addr));
886 size_used += ranges[i].byte_size();
887 prev_last_addr = last_address;
888
889 HeapRegion* start_region = _hrm.addr_to_region(start_address);
890 HeapRegion* last_region = _hrm.addr_to_region(last_address);
891
892 // Check for ranges that start in the same G1 region in which the previous
893 // range ended, and adjust the start address so we don't try to free
894 // the same region again. If the current range is entirely within that
895 // region, skip it.
896 if (start_region == prev_last_region) {
897 start_address = start_region->end();
898 if (start_address > last_address) {
899 continue;
900 }
901 start_region = _hrm.addr_to_region(start_address);
902 }
903 prev_last_region = last_region;
904
905 // After verifying that each region was marked as an archive region by
906 // alloc_archive_regions, set it free and empty and uncommit it.
907 HeapRegion* curr_region = start_region;
908 while (curr_region != NULL) {
909 guarantee(curr_region->is_archive(),
910 "Expected archive region at index %u", curr_region->hrm_index());
911 uint curr_index = curr_region->hrm_index();
912 _old_set.remove(curr_region);
913 curr_region->set_free();
914 curr_region->set_top(curr_region->bottom());
915 if (curr_region != last_region) {
916 curr_region = _hrm.next_region_in_heap(curr_region);
917 } else {
918 curr_region = NULL;
919 }
920 _hrm.shrink_at(curr_index, 1);
921 uncommitted_regions++;
922 }
923
924 // Notify mark-sweep that this is no longer an archive range.
925 G1MarkSweep::set_range_archive(ranges[i], false);
926 }
927
928 if (uncommitted_regions != 0) {
929 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
930 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
931 }
932 decrease_used(size_used);
933 }
934
935 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
936 uint* gc_count_before_ret,
937 uint* gclocker_retry_count_ret) {
938 // The structure of this method has a lot of similarities to
939 // attempt_allocation_slow(). The reason these two were not merged
940 // into a single one is that such a method would require several "if
941 // allocation is not humongous do this, otherwise do that"
942 // conditional paths which would obscure its flow. In fact, an early
943 // version of this code did use a unified method which was harder to
944 // follow and, as a result, it had subtle bugs that were hard to
945 // track down. So keeping these two methods separate allows each to
946 // be more readable. It will be good to keep these two in sync as
947 // much as possible.
948
949 assert_heap_not_locked_and_not_at_safepoint();
950 assert(is_humongous(word_size), "attempt_allocation_humongous() "
951 "should only be called for humongous allocations");
952
953 // Humongous objects can exhaust the heap quickly, so we should check if we
954 // need to start a marking cycle at each humongous object allocation. We do
955 // the check before we do the actual allocation. The reason for doing it
956 // before the allocation is that we avoid having to keep track of the newly
957 // allocated memory while we do a GC.
958 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
959 word_size)) {
960 collect(GCCause::_g1_humongous_allocation);
961 }
962
963 // We will loop until a) we manage to successfully perform the
964 // allocation or b) we successfully schedule a collection which
965 // fails to perform the allocation. b) is the only case when we'll
966 // return NULL.
967 HeapWord* result = NULL;
968 for (int try_count = 1; /* we'll return */; try_count += 1) {
969 bool should_try_gc;
970 uint gc_count_before;
971
972 {
973 MutexLockerEx x(Heap_lock);
974
975 // Given that humongous objects are not allocated in young
976 // regions, we'll first try to do the allocation without doing a
977 // collection hoping that there's enough space in the heap.
978 result = humongous_obj_allocate(word_size, AllocationContext::current());
979 if (result != NULL) {
980 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
981 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
982 return result;
983 }
984
985 if (GCLocker::is_active_and_needs_gc()) {
986 should_try_gc = false;
987 } else {
988 // The GCLocker may not be active but the GCLocker initiated
989 // GC may not yet have been performed (GCLocker::needs_gc()
990 // returns true). In this case we do not try this GC and
991 // wait until the GCLocker initiated GC is performed, and
992 // then retry the allocation.
993 if (GCLocker::needs_gc()) {
994 should_try_gc = false;
995 } else {
996 // Read the GC count while still holding the Heap_lock.
997 gc_count_before = total_collections();
998 should_try_gc = true;
999 }
1000 }
1001 }
1002
1003 if (should_try_gc) {
1004 // If we failed to allocate the humongous object, we should try to
1005 // do a collection pause (if we're allowed) in case it reclaims
1006 // enough space for the allocation to succeed after the pause.
1007
1008 bool succeeded;
1009 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1010 GCCause::_g1_humongous_allocation);
1011 if (result != NULL) {
1012 assert(succeeded, "only way to get back a non-NULL result");
1013 return result;
1014 }
1015
1016 if (succeeded) {
1017 // If we get here we successfully scheduled a collection which
1018 // failed to allocate. No point in trying to allocate
1019 // further. We'll just return NULL.
1020 MutexLockerEx x(Heap_lock);
1021 *gc_count_before_ret = total_collections();
1022 return NULL;
1023 }
1024 } else {
1025 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1026 MutexLockerEx x(Heap_lock);
1027 *gc_count_before_ret = total_collections();
1028 return NULL;
1029 }
1030 // The GCLocker is either active or the GCLocker initiated
1031 // GC has not yet been performed. Stall until it is and
1032 // then retry the allocation.
1033 GCLocker::stall_until_clear();
1034 (*gclocker_retry_count_ret) += 1;
1035 }
1036
1037 // We can reach here if we were unsuccessful in scheduling a
1038 // collection (because another thread beat us to it) or if we were
1039 // stalled due to the GC locker. In either can we should retry the
1040 // allocation attempt in case another thread successfully
1041 // performed a collection and reclaimed enough space. Give a
1042 // warning if we seem to be looping forever.
1043
1044 if ((QueuedAllocationWarningCount > 0) &&
1045 (try_count % QueuedAllocationWarningCount == 0)) {
1046 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1047 "retries %d times", try_count);
1048 }
1049 }
1050
1051 ShouldNotReachHere();
1052 return NULL;
1053 }
1054
1055 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1056 AllocationContext_t context,
1057 bool expect_null_mutator_alloc_region) {
1058 assert_at_safepoint(true /* should_be_vm_thread */);
1059 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1060 "the current alloc region was unexpectedly found to be non-NULL");
1061
1062 if (!is_humongous(word_size)) {
1063 return _allocator->attempt_allocation_locked(word_size, context);
1064 } else {
1065 HeapWord* result = humongous_obj_allocate(word_size, context);
1066 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1067 collector_state()->set_initiate_conc_mark_if_possible(true);
1068 }
1069 return result;
1070 }
1071
1072 ShouldNotReachHere();
1073 }
1074
1075 class PostMCRemSetClearClosure: public HeapRegionClosure {
1076 G1CollectedHeap* _g1h;
1077 ModRefBarrierSet* _mr_bs;
1078 public:
1079 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1080 _g1h(g1h), _mr_bs(mr_bs) {}
1081
1082 bool doHeapRegion(HeapRegion* r) {
1083 HeapRegionRemSet* hrrs = r->rem_set();
1084
1085 _g1h->reset_gc_time_stamps(r);
1086
1087 if (r->is_continues_humongous()) {
1088 // We'll assert that the strong code root list and RSet is empty
1089 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1090 assert(hrrs->occupied() == 0, "RSet should be empty");
1091 } else {
1092 hrrs->clear();
1093 }
1094 // You might think here that we could clear just the cards
1095 // corresponding to the used region. But no: if we leave a dirty card
1096 // in a region we might allocate into, then it would prevent that card
1097 // from being enqueued, and cause it to be missed.
1098 // Re: the performance cost: we shouldn't be doing full GC anyway!
1099 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1100
1101 return false;
1102 }
1103 };
1104
1105 void G1CollectedHeap::clear_rsets_post_compaction() {
1106 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1107 heap_region_iterate(&rs_clear);
1108 }
1109
1110 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1111 G1CollectedHeap* _g1h;
1112 UpdateRSOopClosure _cl;
1113 public:
1114 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1115 _cl(g1->g1_rem_set(), worker_i),
1116 _g1h(g1)
1117 { }
1118
1119 bool doHeapRegion(HeapRegion* r) {
1120 if (!r->is_continues_humongous()) {
1121 _cl.set_from(r);
1122 r->oop_iterate(&_cl);
1123 }
1124 return false;
1125 }
1126 };
1127
1128 class ParRebuildRSTask: public AbstractGangTask {
1129 G1CollectedHeap* _g1;
1130 HeapRegionClaimer _hrclaimer;
1131
1132 public:
1133 ParRebuildRSTask(G1CollectedHeap* g1) :
1134 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1135
1136 void work(uint worker_id) {
1137 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1138 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1139 }
1140 };
1141
1142 class PostCompactionPrinterClosure: public HeapRegionClosure {
1143 private:
1144 G1HRPrinter* _hr_printer;
1145 public:
1146 bool doHeapRegion(HeapRegion* hr) {
1147 assert(!hr->is_young(), "not expecting to find young regions");
1148 _hr_printer->post_compaction(hr);
1149 return false;
1150 }
1151
1152 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1153 : _hr_printer(hr_printer) { }
1154 };
1155
1156 void G1CollectedHeap::print_hrm_post_compaction() {
1157 if (_hr_printer.is_active()) {
1158 PostCompactionPrinterClosure cl(hr_printer());
1159 heap_region_iterate(&cl);
1160 }
1161
1162 }
1163
1164 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1165 bool clear_all_soft_refs) {
1166 assert_at_safepoint(true /* should_be_vm_thread */);
1167
1168 if (GCLocker::check_active_before_gc()) {
1169 return false;
1170 }
1171
1172 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1173 gc_timer->register_gc_start();
1174
1175 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1176 GCIdMark gc_id_mark;
1177 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1178
1179 SvcGCMarker sgcm(SvcGCMarker::FULL);
1180 ResourceMark rm;
1181
1182 print_heap_before_gc();
1183 print_heap_regions();
1184 trace_heap_before_gc(gc_tracer);
1185
1186 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1187
1188 _verifier->verify_region_sets_optional();
1189
1190 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1191 collector_policy()->should_clear_all_soft_refs();
1192
1193 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1194
1195 {
1196 IsGCActiveMark x;
1197
1198 // Timing
1199 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1200 GCTraceCPUTime tcpu;
1201
1202 {
1203 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1204 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1205 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1206
1207 G1HeapTransition heap_transition(this);
1208 g1_policy()->record_full_collection_start();
1209
1210 // Note: When we have a more flexible GC logging framework that
1211 // allows us to add optional attributes to a GC log record we
1212 // could consider timing and reporting how long we wait in the
1213 // following two methods.
1214 wait_while_free_regions_coming();
1215 // If we start the compaction before the CM threads finish
1216 // scanning the root regions we might trip them over as we'll
1217 // be moving objects / updating references. So let's wait until
1218 // they are done. By telling them to abort, they should complete
1219 // early.
1220 _cm->root_regions()->abort();
1221 _cm->root_regions()->wait_until_scan_finished();
1222 append_secondary_free_list_if_not_empty_with_lock();
1223
1224 gc_prologue(true);
1225 increment_total_collections(true /* full gc */);
1226 increment_old_marking_cycles_started();
1227
1228 assert(used() == recalculate_used(), "Should be equal");
1229
1230 _verifier->verify_before_gc();
1231
1232 _verifier->check_bitmaps("Full GC Start");
1233 pre_full_gc_dump(gc_timer);
1234
1235 #if defined(COMPILER2) || INCLUDE_JVMCI
1236 DerivedPointerTable::clear();
1237 #endif
1238
1239 // Disable discovery and empty the discovered lists
1240 // for the CM ref processor.
1241 ref_processor_cm()->disable_discovery();
1242 ref_processor_cm()->abandon_partial_discovery();
1243 ref_processor_cm()->verify_no_references_recorded();
1244
1245 // Abandon current iterations of concurrent marking and concurrent
1246 // refinement, if any are in progress.
1247 concurrent_mark()->abort();
1248
1249 // Make sure we'll choose a new allocation region afterwards.
1250 _allocator->release_mutator_alloc_region();
1251 _allocator->abandon_gc_alloc_regions();
1252 g1_rem_set()->cleanupHRRS();
1253
1254 // We may have added regions to the current incremental collection
1255 // set between the last GC or pause and now. We need to clear the
1256 // incremental collection set and then start rebuilding it afresh
1257 // after this full GC.
1258 abandon_collection_set(collection_set());
1259
1260 tear_down_region_sets(false /* free_list_only */);
1261 collector_state()->set_gcs_are_young(true);
1262
1263 // See the comments in g1CollectedHeap.hpp and
1264 // G1CollectedHeap::ref_processing_init() about
1265 // how reference processing currently works in G1.
1266
1267 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1268 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1269
1270 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1271 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1272
1273 ref_processor_stw()->enable_discovery();
1274 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1275
1276 // Do collection work
1277 {
1278 HandleMark hm; // Discard invalid handles created during gc
1279 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1280 }
1281
1282 assert(num_free_regions() == 0, "we should not have added any free regions");
1283 rebuild_region_sets(false /* free_list_only */);
1284
1285 // Enqueue any discovered reference objects that have
1286 // not been removed from the discovered lists.
1287 ref_processor_stw()->enqueue_discovered_references();
1288
1289 #if defined(COMPILER2) || INCLUDE_JVMCI
1290 DerivedPointerTable::update_pointers();
1291 #endif
1292
1293 MemoryService::track_memory_usage();
1294
1295 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1296 ref_processor_stw()->verify_no_references_recorded();
1297
1298 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1299 ClassLoaderDataGraph::purge();
1300 MetaspaceAux::verify_metrics();
1301
1302 // Note: since we've just done a full GC, concurrent
1303 // marking is no longer active. Therefore we need not
1304 // re-enable reference discovery for the CM ref processor.
1305 // That will be done at the start of the next marking cycle.
1306 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1307 ref_processor_cm()->verify_no_references_recorded();
1308
1309 reset_gc_time_stamp();
1310 // Since everything potentially moved, we will clear all remembered
1311 // sets, and clear all cards. Later we will rebuild remembered
1312 // sets. We will also reset the GC time stamps of the regions.
1313 clear_rsets_post_compaction();
1314 check_gc_time_stamps();
1315
1316 resize_if_necessary_after_full_collection();
1317
1318 // We should do this after we potentially resize the heap so
1319 // that all the COMMIT / UNCOMMIT events are generated before
1320 // the compaction events.
1321 print_hrm_post_compaction();
1322
1323 if (_hot_card_cache->use_cache()) {
1324 _hot_card_cache->reset_card_counts();
1325 _hot_card_cache->reset_hot_cache();
1326 }
1327
1328 // Rebuild remembered sets of all regions.
1329 uint n_workers =
1330 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1331 workers()->active_workers(),
1332 Threads::number_of_non_daemon_threads());
1333 workers()->update_active_workers(n_workers);
1334 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1335
1336 ParRebuildRSTask rebuild_rs_task(this);
1337 workers()->run_task(&rebuild_rs_task);
1338
1339 // Rebuild the strong code root lists for each region
1340 rebuild_strong_code_roots();
1341
1342 if (true) { // FIXME
1343 MetaspaceGC::compute_new_size();
1344 }
1345
1346 #ifdef TRACESPINNING
1347 ParallelTaskTerminator::print_termination_counts();
1348 #endif
1349
1350 // Discard all rset updates
1351 JavaThread::dirty_card_queue_set().abandon_logs();
1352 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1353
1354 // At this point there should be no regions in the
1355 // entire heap tagged as young.
1356 assert(check_young_list_empty(), "young list should be empty at this point");
1357
1358 // Update the number of full collections that have been completed.
1359 increment_old_marking_cycles_completed(false /* concurrent */);
1360
1361 _hrm.verify_optional();
1362 _verifier->verify_region_sets_optional();
1363
1364 _verifier->verify_after_gc();
1365
1366 // Clear the previous marking bitmap, if needed for bitmap verification.
1367 // Note we cannot do this when we clear the next marking bitmap in
1368 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1369 // objects marked during a full GC against the previous bitmap.
1370 // But we need to clear it before calling check_bitmaps below since
1371 // the full GC has compacted objects and updated TAMS but not updated
1372 // the prev bitmap.
1373 if (G1VerifyBitmaps) {
1374 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1375 _cm->clear_prev_bitmap(workers());
1376 }
1377 _verifier->check_bitmaps("Full GC End");
1378
1379 // Start a new incremental collection set for the next pause
1380 collection_set()->start_incremental_building();
1381
1382 clear_cset_fast_test();
1383
1384 _allocator->init_mutator_alloc_region();
1385
1386 g1_policy()->record_full_collection_end();
1387
1388 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1389 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1390 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1391 // before any GC notifications are raised.
1392 g1mm()->update_sizes();
1393
1394 gc_epilogue(true);
1395
1396 heap_transition.print();
1397
1398 print_heap_after_gc();
1399 print_heap_regions();
1400 trace_heap_after_gc(gc_tracer);
1401
1402 post_full_gc_dump(gc_timer);
1403 }
1404
1405 gc_timer->register_gc_end();
1406 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1407 }
1408
1409 return true;
1410 }
1411
1412 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1413 // Currently, there is no facility in the do_full_collection(bool) API to notify
1414 // the caller that the collection did not succeed (e.g., because it was locked
1415 // out by the GC locker). So, right now, we'll ignore the return value.
1416 bool dummy = do_full_collection(true, /* explicit_gc */
1417 clear_all_soft_refs);
1418 }
1419
1420 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1421 // Include bytes that will be pre-allocated to support collections, as "used".
1422 const size_t used_after_gc = used();
1423 const size_t capacity_after_gc = capacity();
1424 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1425
1426 // This is enforced in arguments.cpp.
1427 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1428 "otherwise the code below doesn't make sense");
1429
1430 // We don't have floating point command-line arguments
1431 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1432 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1433 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1434 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1435
1436 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1437 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1438
1439 // We have to be careful here as these two calculations can overflow
1440 // 32-bit size_t's.
1441 double used_after_gc_d = (double) used_after_gc;
1442 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1443 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1444
1445 // Let's make sure that they are both under the max heap size, which
1446 // by default will make them fit into a size_t.
1447 double desired_capacity_upper_bound = (double) max_heap_size;
1448 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1449 desired_capacity_upper_bound);
1450 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1451 desired_capacity_upper_bound);
1452
1453 // We can now safely turn them into size_t's.
1454 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1455 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1456
1457 // This assert only makes sense here, before we adjust them
1458 // with respect to the min and max heap size.
1459 assert(minimum_desired_capacity <= maximum_desired_capacity,
1460 "minimum_desired_capacity = " SIZE_FORMAT ", "
1461 "maximum_desired_capacity = " SIZE_FORMAT,
1462 minimum_desired_capacity, maximum_desired_capacity);
1463
1464 // Should not be greater than the heap max size. No need to adjust
1465 // it with respect to the heap min size as it's a lower bound (i.e.,
1466 // we'll try to make the capacity larger than it, not smaller).
1467 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1468 // Should not be less than the heap min size. No need to adjust it
1469 // with respect to the heap max size as it's an upper bound (i.e.,
1470 // we'll try to make the capacity smaller than it, not greater).
1471 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1472
1473 if (capacity_after_gc < minimum_desired_capacity) {
1474 // Don't expand unless it's significant
1475 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1476
1477 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1478 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1479 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1480
1481 expand(expand_bytes, _workers);
1482
1483 // No expansion, now see if we want to shrink
1484 } else if (capacity_after_gc > maximum_desired_capacity) {
1485 // Capacity too large, compute shrinking size
1486 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1487
1488 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1489 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1490 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1491
1492 shrink(shrink_bytes);
1493 }
1494 }
1495
1496 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1497 AllocationContext_t context,
1498 bool do_gc,
1499 bool clear_all_soft_refs,
1500 bool expect_null_mutator_alloc_region,
1501 bool* gc_succeeded) {
1502 *gc_succeeded = true;
1503 // Let's attempt the allocation first.
1504 HeapWord* result =
1505 attempt_allocation_at_safepoint(word_size,
1506 context,
1507 expect_null_mutator_alloc_region);
1508 if (result != NULL) {
1509 assert(*gc_succeeded, "sanity");
1510 return result;
1511 }
1512
1513 // In a G1 heap, we're supposed to keep allocation from failing by
1514 // incremental pauses. Therefore, at least for now, we'll favor
1515 // expansion over collection. (This might change in the future if we can
1516 // do something smarter than full collection to satisfy a failed alloc.)
1517 result = expand_and_allocate(word_size, context);
1518 if (result != NULL) {
1519 assert(*gc_succeeded, "sanity");
1520 return result;
1521 }
1522
1523 if (do_gc) {
1524 // Expansion didn't work, we'll try to do a Full GC.
1525 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1526 clear_all_soft_refs);
1527 }
1528
1529 return NULL;
1530 }
1531
1532 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1533 AllocationContext_t context,
1534 bool* succeeded) {
1535 assert_at_safepoint(true /* should_be_vm_thread */);
1536
1537 // Attempts to allocate followed by Full GC.
1538 HeapWord* result =
1539 satisfy_failed_allocation_helper(word_size,
1540 context,
1541 true, /* do_gc */
1542 false, /* clear_all_soft_refs */
1543 false, /* expect_null_mutator_alloc_region */
1544 succeeded);
1545
1546 if (result != NULL || !*succeeded) {
1547 return result;
1548 }
1549
1550 // Attempts to allocate followed by Full GC that will collect all soft references.
1551 result = satisfy_failed_allocation_helper(word_size,
1552 context,
1553 true, /* do_gc */
1554 true, /* clear_all_soft_refs */
1555 true, /* expect_null_mutator_alloc_region */
1556 succeeded);
1557
1558 if (result != NULL || !*succeeded) {
1559 return result;
1560 }
1561
1562 // Attempts to allocate, no GC
1563 result = satisfy_failed_allocation_helper(word_size,
1564 context,
1565 false, /* do_gc */
1566 false, /* clear_all_soft_refs */
1567 true, /* expect_null_mutator_alloc_region */
1568 succeeded);
1569
1570 if (result != NULL) {
1571 assert(*succeeded, "sanity");
1572 return result;
1573 }
1574
1575 assert(!collector_policy()->should_clear_all_soft_refs(),
1576 "Flag should have been handled and cleared prior to this point");
1577
1578 // What else? We might try synchronous finalization later. If the total
1579 // space available is large enough for the allocation, then a more
1580 // complete compaction phase than we've tried so far might be
1581 // appropriate.
1582 assert(*succeeded, "sanity");
1583 return NULL;
1584 }
1585
1586 // Attempting to expand the heap sufficiently
1587 // to support an allocation of the given "word_size". If
1588 // successful, perform the allocation and return the address of the
1589 // allocated block, or else "NULL".
1590
1591 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1592 assert_at_safepoint(true /* should_be_vm_thread */);
1593
1594 _verifier->verify_region_sets_optional();
1595
1596 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1597 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1598 word_size * HeapWordSize);
1599
1600
1601 if (expand(expand_bytes, _workers)) {
1602 _hrm.verify_optional();
1603 _verifier->verify_region_sets_optional();
1604 return attempt_allocation_at_safepoint(word_size,
1605 context,
1606 false /* expect_null_mutator_alloc_region */);
1607 }
1608 return NULL;
1609 }
1610
1611 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1612 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1613 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1614 HeapRegion::GrainBytes);
1615
1616 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1617 expand_bytes, aligned_expand_bytes);
1618
1619 if (is_maximal_no_gc()) {
1620 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1621 return false;
1622 }
1623
1624 double expand_heap_start_time_sec = os::elapsedTime();
1625 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1626 assert(regions_to_expand > 0, "Must expand by at least one region");
1627
1628 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1629 if (expand_time_ms != NULL) {
1630 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1631 }
1632
1633 if (expanded_by > 0) {
1634 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1635 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1636 g1_policy()->record_new_heap_size(num_regions());
1637 } else {
1638 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1639
1640 // The expansion of the virtual storage space was unsuccessful.
1641 // Let's see if it was because we ran out of swap.
1642 if (G1ExitOnExpansionFailure &&
1643 _hrm.available() >= regions_to_expand) {
1644 // We had head room...
1645 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1646 }
1647 }
1648 return regions_to_expand > 0;
1649 }
1650
1651 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1652 size_t aligned_shrink_bytes =
1653 ReservedSpace::page_align_size_down(shrink_bytes);
1654 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1655 HeapRegion::GrainBytes);
1656 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1657
1658 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1659 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1660
1661
1662 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",
1663 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1664 if (num_regions_removed > 0) {
1665 g1_policy()->record_new_heap_size(num_regions());
1666 } else {
1667 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1668 }
1669 }
1670
1671 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1672 _verifier->verify_region_sets_optional();
1673
1674 // We should only reach here at the end of a Full GC which means we
1675 // should not not be holding to any GC alloc regions. The method
1676 // below will make sure of that and do any remaining clean up.
1677 _allocator->abandon_gc_alloc_regions();
1678
1679 // Instead of tearing down / rebuilding the free lists here, we
1680 // could instead use the remove_all_pending() method on free_list to
1681 // remove only the ones that we need to remove.
1682 tear_down_region_sets(true /* free_list_only */);
1683 shrink_helper(shrink_bytes);
1684 rebuild_region_sets(true /* free_list_only */);
1685
1686 _hrm.verify_optional();
1687 _verifier->verify_region_sets_optional();
1688 }
1689
1690 // Public methods.
1691
1692 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1693 CollectedHeap(),
1694 _collector_policy(collector_policy),
1695 _g1_policy(create_g1_policy()),
1696 _collection_set(this, _g1_policy),
1697 _dirty_card_queue_set(false),
1698 _is_alive_closure_cm(this),
1699 _is_alive_closure_stw(this),
1700 _ref_processor_cm(NULL),
1701 _ref_processor_stw(NULL),
1702 _bot(NULL),
1703 _hot_card_cache(NULL),
1704 _g1_rem_set(NULL),
1705 _cg1r(NULL),
1706 _g1mm(NULL),
1707 _refine_cte_cl(NULL),
1708 _preserved_marks_set(true /* in_c_heap */),
1709 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1710 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1711 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1712 _humongous_reclaim_candidates(),
1713 _has_humongous_reclaim_candidates(false),
1714 _archive_allocator(NULL),
1715 _free_regions_coming(false),
1716 _gc_time_stamp(0),
1717 _summary_bytes_used(0),
1718 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1719 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1720 _expand_heap_after_alloc_failure(true),
1721 _old_marking_cycles_started(0),
1722 _old_marking_cycles_completed(0),
1723 _in_cset_fast_test(),
1724 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1725 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1726
1727 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1728 /* are_GC_task_threads */true,
1729 /* are_ConcurrentGC_threads */false);
1730 _workers->initialize_workers();
1731 _verifier = new G1HeapVerifier(this);
1732
1733 _allocator = G1Allocator::create_allocator(this);
1734
1735 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1736
1737 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1738
1739 // Override the default _filler_array_max_size so that no humongous filler
1740 // objects are created.
1741 _filler_array_max_size = _humongous_object_threshold_in_words;
1742
1743 uint n_queues = ParallelGCThreads;
1744 _task_queues = new RefToScanQueueSet(n_queues);
1745
1746 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1747
1748 for (uint i = 0; i < n_queues; i++) {
1749 RefToScanQueue* q = new RefToScanQueue();
1750 q->initialize();
1751 _task_queues->register_queue(i, q);
1752 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1753 }
1754
1755 // Initialize the G1EvacuationFailureALot counters and flags.
1756 NOT_PRODUCT(reset_evacuation_should_fail();)
1757
1758 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1759 }
1760
1761 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1762 size_t size,
1763 size_t translation_factor) {
1764 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1765 // Allocate a new reserved space, preferring to use large pages.
1766 ReservedSpace rs(size, preferred_page_size);
1767 G1RegionToSpaceMapper* result =
1768 G1RegionToSpaceMapper::create_mapper(rs,
1769 size,
1770 rs.alignment(),
1771 HeapRegion::GrainBytes,
1772 translation_factor,
1773 mtGC);
1774
1775 os::trace_page_sizes_for_requested_size(description,
1776 size,
1777 preferred_page_size,
1778 rs.alignment(),
1779 rs.base(),
1780 rs.size());
1781
1782 return result;
1783 }
1784
1785 jint G1CollectedHeap::initialize() {
1786 CollectedHeap::pre_initialize();
1787 os::enable_vtime();
1788
1789 // Necessary to satisfy locking discipline assertions.
1790
1791 MutexLocker x(Heap_lock);
1792
1793 // While there are no constraints in the GC code that HeapWordSize
1794 // be any particular value, there are multiple other areas in the
1795 // system which believe this to be true (e.g. oop->object_size in some
1796 // cases incorrectly returns the size in wordSize units rather than
1797 // HeapWordSize).
1798 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1799
1800 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1801 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1802 size_t heap_alignment = collector_policy()->heap_alignment();
1803
1804 // Ensure that the sizes are properly aligned.
1805 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1806 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1807 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1808
1809 _refine_cte_cl = new RefineCardTableEntryClosure();
1810
1811 jint ecode = JNI_OK;
1812 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1813 if (_cg1r == NULL) {
1814 return ecode;
1815 }
1816
1817 // Reserve the maximum.
1818
1819 // When compressed oops are enabled, the preferred heap base
1820 // is calculated by subtracting the requested size from the
1821 // 32Gb boundary and using the result as the base address for
1822 // heap reservation. If the requested size is not aligned to
1823 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1824 // into the ReservedHeapSpace constructor) then the actual
1825 // base of the reserved heap may end up differing from the
1826 // address that was requested (i.e. the preferred heap base).
1827 // If this happens then we could end up using a non-optimal
1828 // compressed oops mode.
1829
1830 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1831 heap_alignment);
1832
1833 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1834
1835 // Create the barrier set for the entire reserved region.
1836 G1SATBCardTableLoggingModRefBS* bs
1837 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1838 bs->initialize();
1839 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1840 set_barrier_set(bs);
1841
1842 // Create the hot card cache.
1843 _hot_card_cache = new G1HotCardCache(this);
1844
1845 // Also create a G1 rem set.
1846 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1847
1848 // Carve out the G1 part of the heap.
1849 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1850 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1851 G1RegionToSpaceMapper* heap_storage =
1852 G1RegionToSpaceMapper::create_mapper(g1_rs,
1853 g1_rs.size(),
1854 page_size,
1855 HeapRegion::GrainBytes,
1856 1,
1857 mtJavaHeap);
1858 os::trace_page_sizes("Heap",
1859 collector_policy()->min_heap_byte_size(),
1860 max_byte_size,
1861 page_size,
1862 heap_rs.base(),
1863 heap_rs.size());
1864 heap_storage->set_mapping_changed_listener(&_listener);
1865
1866 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1867 G1RegionToSpaceMapper* bot_storage =
1868 create_aux_memory_mapper("Block Offset Table",
1869 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1870 G1BlockOffsetTable::heap_map_factor());
1871
1872 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1873 G1RegionToSpaceMapper* cardtable_storage =
1874 create_aux_memory_mapper("Card Table",
1875 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1876 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1877
1878 G1RegionToSpaceMapper* card_counts_storage =
1879 create_aux_memory_mapper("Card Counts Table",
1880 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1881 G1CardCounts::heap_map_factor());
1882
1883 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1884 G1RegionToSpaceMapper* prev_bitmap_storage =
1885 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1886 G1RegionToSpaceMapper* next_bitmap_storage =
1887 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1888
1889 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1890 g1_barrier_set()->initialize(cardtable_storage);
1891 // Do later initialization work for concurrent refinement.
1892 _hot_card_cache->initialize(card_counts_storage);
1893
1894 // 6843694 - ensure that the maximum region index can fit
1895 // in the remembered set structures.
1896 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1897 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1898
1899 g1_rem_set()->initialize(max_capacity(), max_regions());
1900
1901 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1902 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1903 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1904 "too many cards per region");
1905
1906 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1907
1908 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1909
1910 {
1911 HeapWord* start = _hrm.reserved().start();
1912 HeapWord* end = _hrm.reserved().end();
1913 size_t granularity = HeapRegion::GrainBytes;
1914
1915 _in_cset_fast_test.initialize(start, end, granularity);
1916 _humongous_reclaim_candidates.initialize(start, end, granularity);
1917 }
1918
1919 // Create the G1ConcurrentMark data structure and thread.
1920 // (Must do this late, so that "max_regions" is defined.)
1921 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1922 if (_cm == NULL || !_cm->completed_initialization()) {
1923 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1924 return JNI_ENOMEM;
1925 }
1926 _cmThread = _cm->cmThread();
1927
1928 // Now expand into the initial heap size.
1929 if (!expand(init_byte_size, _workers)) {
1930 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1931 return JNI_ENOMEM;
1932 }
1933
1934 // Perform any initialization actions delegated to the policy.
1935 g1_policy()->init(this, &_collection_set);
1936
1937 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1938 SATB_Q_FL_lock,
1939 G1SATBProcessCompletedThreshold,
1940 Shared_SATB_Q_lock);
1941
1942 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1943 DirtyCardQ_CBL_mon,
1944 DirtyCardQ_FL_lock,
1945 (int)concurrent_g1_refine()->yellow_zone(),
1946 (int)concurrent_g1_refine()->red_zone(),
1947 Shared_DirtyCardQ_lock,
1948 NULL, // fl_owner
1949 true); // init_free_ids
1950
1951 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1952 DirtyCardQ_CBL_mon,
1953 DirtyCardQ_FL_lock,
1954 -1, // never trigger processing
1955 -1, // no limit on length
1956 Shared_DirtyCardQ_lock,
1957 &JavaThread::dirty_card_queue_set());
1958
1959 // Here we allocate the dummy HeapRegion that is required by the
1960 // G1AllocRegion class.
1961 HeapRegion* dummy_region = _hrm.get_dummy_region();
1962
1963 // We'll re-use the same region whether the alloc region will
1964 // require BOT updates or not and, if it doesn't, then a non-young
1965 // region will complain that it cannot support allocations without
1966 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1967 dummy_region->set_eden();
1968 // Make sure it's full.
1969 dummy_region->set_top(dummy_region->end());
1970 G1AllocRegion::setup(this, dummy_region);
1971
1972 _allocator->init_mutator_alloc_region();
1973
1974 // Do create of the monitoring and management support so that
1975 // values in the heap have been properly initialized.
1976 _g1mm = new G1MonitoringSupport(this);
1977
1978 G1StringDedup::initialize();
1979
1980 _preserved_marks_set.init(ParallelGCThreads);
1981
1982 _collection_set.initialize(max_regions());
1983
1984 return JNI_OK;
1985 }
1986
1987 void G1CollectedHeap::stop() {
1988 // Stop all concurrent threads. We do this to make sure these threads
1989 // do not continue to execute and access resources (e.g. logging)
1990 // that are destroyed during shutdown.
1991 _cg1r->stop();
1992 _cmThread->stop();
1993 if (G1StringDedup::is_enabled()) {
1994 G1StringDedup::stop();
1995 }
1996 }
1997
1998 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1999 return HeapRegion::max_region_size();
2000 }
2001
2002 void G1CollectedHeap::post_initialize() {
2003 ref_processing_init();
2004 }
2005
2006 void G1CollectedHeap::ref_processing_init() {
2007 // Reference processing in G1 currently works as follows:
2008 //
2009 // * There are two reference processor instances. One is
2010 // used to record and process discovered references
2011 // during concurrent marking; the other is used to
2012 // record and process references during STW pauses
2013 // (both full and incremental).
2014 // * Both ref processors need to 'span' the entire heap as
2015 // the regions in the collection set may be dotted around.
2016 //
2017 // * For the concurrent marking ref processor:
2018 // * Reference discovery is enabled at initial marking.
2019 // * Reference discovery is disabled and the discovered
2020 // references processed etc during remarking.
2021 // * Reference discovery is MT (see below).
2022 // * Reference discovery requires a barrier (see below).
2023 // * Reference processing may or may not be MT
2024 // (depending on the value of ParallelRefProcEnabled
2025 // and ParallelGCThreads).
2026 // * A full GC disables reference discovery by the CM
2027 // ref processor and abandons any entries on it's
2028 // discovered lists.
2029 //
2030 // * For the STW processor:
2031 // * Non MT discovery is enabled at the start of a full GC.
2032 // * Processing and enqueueing during a full GC is non-MT.
2033 // * During a full GC, references are processed after marking.
2034 //
2035 // * Discovery (may or may not be MT) is enabled at the start
2036 // of an incremental evacuation pause.
2037 // * References are processed near the end of a STW evacuation pause.
2038 // * For both types of GC:
2039 // * Discovery is atomic - i.e. not concurrent.
2040 // * Reference discovery will not need a barrier.
2041
2042 MemRegion mr = reserved_region();
2043
2044 // Concurrent Mark ref processor
2045 _ref_processor_cm =
2046 new ReferenceProcessor(mr, // span
2047 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2048 // mt processing
2049 ParallelGCThreads,
2050 // degree of mt processing
2051 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2052 // mt discovery
2053 MAX2(ParallelGCThreads, ConcGCThreads),
2054 // degree of mt discovery
2055 false,
2056 // Reference discovery is not atomic
2057 &_is_alive_closure_cm);
2058 // is alive closure
2059 // (for efficiency/performance)
2060
2061 // STW ref processor
2062 _ref_processor_stw =
2063 new ReferenceProcessor(mr, // span
2064 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2065 // mt processing
2066 ParallelGCThreads,
2067 // degree of mt processing
2068 (ParallelGCThreads > 1),
2069 // mt discovery
2070 ParallelGCThreads,
2071 // degree of mt discovery
2072 true,
2073 // Reference discovery is atomic
2074 &_is_alive_closure_stw);
2075 // is alive closure
2076 // (for efficiency/performance)
2077 }
2078
2079 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2080 return _collector_policy;
2081 }
2082
2083 size_t G1CollectedHeap::capacity() const {
2084 return _hrm.length() * HeapRegion::GrainBytes;
2085 }
2086
2087 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2088 hr->reset_gc_time_stamp();
2089 }
2090
2091 #ifndef PRODUCT
2092
2093 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2094 private:
2095 unsigned _gc_time_stamp;
2096 bool _failures;
2097
2098 public:
2099 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2100 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2101
2102 virtual bool doHeapRegion(HeapRegion* hr) {
2103 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2104 if (_gc_time_stamp != region_gc_time_stamp) {
2105 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2106 region_gc_time_stamp, _gc_time_stamp);
2107 _failures = true;
2108 }
2109 return false;
2110 }
2111
2112 bool failures() { return _failures; }
2113 };
2114
2115 void G1CollectedHeap::check_gc_time_stamps() {
2116 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2117 heap_region_iterate(&cl);
2118 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2119 }
2120 #endif // PRODUCT
2121
2122 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2123 _hot_card_cache->drain(cl, worker_i);
2124 }
2125
2126 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2127 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2128 size_t n_completed_buffers = 0;
2129 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2130 n_completed_buffers++;
2131 }
2132 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2133 dcqs.clear_n_completed_buffers();
2134 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2135 }
2136
2137 // Computes the sum of the storage used by the various regions.
2138 size_t G1CollectedHeap::used() const {
2139 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2140 if (_archive_allocator != NULL) {
2141 result += _archive_allocator->used();
2142 }
2143 return result;
2144 }
2145
2146 size_t G1CollectedHeap::used_unlocked() const {
2147 return _summary_bytes_used;
2148 }
2149
2150 class SumUsedClosure: public HeapRegionClosure {
2151 size_t _used;
2152 public:
2153 SumUsedClosure() : _used(0) {}
2154 bool doHeapRegion(HeapRegion* r) {
2155 _used += r->used();
2156 return false;
2157 }
2158 size_t result() { return _used; }
2159 };
2160
2161 size_t G1CollectedHeap::recalculate_used() const {
2162 double recalculate_used_start = os::elapsedTime();
2163
2164 SumUsedClosure blk;
2165 heap_region_iterate(&blk);
2166
2167 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2168 return blk.result();
2169 }
2170
2171 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2172 switch (cause) {
2173 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2174 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2175 case GCCause::_update_allocation_context_stats_inc: return true;
2176 case GCCause::_wb_conc_mark: return true;
2177 default : return false;
2178 }
2179 }
2180
2181 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2182 switch (cause) {
2183 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2184 case GCCause::_g1_humongous_allocation: return true;
2185 default: return is_user_requested_concurrent_full_gc(cause);
2186 }
2187 }
2188
2189 #ifndef PRODUCT
2190 void G1CollectedHeap::allocate_dummy_regions() {
2191 // Let's fill up most of the region
2192 size_t word_size = HeapRegion::GrainWords - 1024;
2193 // And as a result the region we'll allocate will be humongous.
2194 guarantee(is_humongous(word_size), "sanity");
2195
2196 // _filler_array_max_size is set to humongous object threshold
2197 // but temporarily change it to use CollectedHeap::fill_with_object().
2198 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2199
2200 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2201 // Let's use the existing mechanism for the allocation
2202 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2203 AllocationContext::system());
2204 if (dummy_obj != NULL) {
2205 MemRegion mr(dummy_obj, word_size);
2206 CollectedHeap::fill_with_object(mr);
2207 } else {
2208 // If we can't allocate once, we probably cannot allocate
2209 // again. Let's get out of the loop.
2210 break;
2211 }
2212 }
2213 }
2214 #endif // !PRODUCT
2215
2216 void G1CollectedHeap::increment_old_marking_cycles_started() {
2217 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2218 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2219 "Wrong marking cycle count (started: %d, completed: %d)",
2220 _old_marking_cycles_started, _old_marking_cycles_completed);
2221
2222 _old_marking_cycles_started++;
2223 }
2224
2225 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2226 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2227
2228 // We assume that if concurrent == true, then the caller is a
2229 // concurrent thread that was joined the Suspendible Thread
2230 // Set. If there's ever a cheap way to check this, we should add an
2231 // assert here.
2232
2233 // Given that this method is called at the end of a Full GC or of a
2234 // concurrent cycle, and those can be nested (i.e., a Full GC can
2235 // interrupt a concurrent cycle), the number of full collections
2236 // completed should be either one (in the case where there was no
2237 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2238 // behind the number of full collections started.
2239
2240 // This is the case for the inner caller, i.e. a Full GC.
2241 assert(concurrent ||
2242 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2243 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2244 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2245 "is inconsistent with _old_marking_cycles_completed = %u",
2246 _old_marking_cycles_started, _old_marking_cycles_completed);
2247
2248 // This is the case for the outer caller, i.e. the concurrent cycle.
2249 assert(!concurrent ||
2250 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2251 "for outer caller (concurrent cycle): "
2252 "_old_marking_cycles_started = %u "
2253 "is inconsistent with _old_marking_cycles_completed = %u",
2254 _old_marking_cycles_started, _old_marking_cycles_completed);
2255
2256 _old_marking_cycles_completed += 1;
2257
2258 // We need to clear the "in_progress" flag in the CM thread before
2259 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2260 // is set) so that if a waiter requests another System.gc() it doesn't
2261 // incorrectly see that a marking cycle is still in progress.
2262 if (concurrent) {
2263 _cmThread->set_idle();
2264 }
2265
2266 // This notify_all() will ensure that a thread that called
2267 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2268 // and it's waiting for a full GC to finish will be woken up. It is
2269 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2270 FullGCCount_lock->notify_all();
2271 }
2272
2273 void G1CollectedHeap::collect(GCCause::Cause cause) {
2274 assert_heap_not_locked();
2275
2276 uint gc_count_before;
2277 uint old_marking_count_before;
2278 uint full_gc_count_before;
2279 bool retry_gc;
2280
2281 do {
2282 retry_gc = false;
2283
2284 {
2285 MutexLocker ml(Heap_lock);
2286
2287 // Read the GC count while holding the Heap_lock
2288 gc_count_before = total_collections();
2289 full_gc_count_before = total_full_collections();
2290 old_marking_count_before = _old_marking_cycles_started;
2291 }
2292
2293 if (should_do_concurrent_full_gc(cause)) {
2294 // Schedule an initial-mark evacuation pause that will start a
2295 // concurrent cycle. We're setting word_size to 0 which means that
2296 // we are not requesting a post-GC allocation.
2297 VM_G1IncCollectionPause op(gc_count_before,
2298 0, /* word_size */
2299 true, /* should_initiate_conc_mark */
2300 g1_policy()->max_pause_time_ms(),
2301 cause);
2302 op.set_allocation_context(AllocationContext::current());
2303
2304 VMThread::execute(&op);
2305 if (!op.pause_succeeded()) {
2306 if (old_marking_count_before == _old_marking_cycles_started) {
2307 retry_gc = op.should_retry_gc();
2308 } else {
2309 // A Full GC happened while we were trying to schedule the
2310 // initial-mark GC. No point in starting a new cycle given
2311 // that the whole heap was collected anyway.
2312 }
2313
2314 if (retry_gc) {
2315 if (GCLocker::is_active_and_needs_gc()) {
2316 GCLocker::stall_until_clear();
2317 }
2318 }
2319 }
2320 } else {
2321 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2322 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2323
2324 // Schedule a standard evacuation pause. We're setting word_size
2325 // to 0 which means that we are not requesting a post-GC allocation.
2326 VM_G1IncCollectionPause op(gc_count_before,
2327 0, /* word_size */
2328 false, /* should_initiate_conc_mark */
2329 g1_policy()->max_pause_time_ms(),
2330 cause);
2331 VMThread::execute(&op);
2332 } else {
2333 // Schedule a Full GC.
2334 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2335 VMThread::execute(&op);
2336 }
2337 }
2338 } while (retry_gc);
2339 }
2340
2341 bool G1CollectedHeap::is_in(const void* p) const {
2342 if (_hrm.reserved().contains(p)) {
2343 // Given that we know that p is in the reserved space,
2344 // heap_region_containing() should successfully
2345 // return the containing region.
2346 HeapRegion* hr = heap_region_containing(p);
2347 return hr->is_in(p);
2348 } else {
2349 return false;
2350 }
2351 }
2352
2353 #ifdef ASSERT
2354 bool G1CollectedHeap::is_in_exact(const void* p) const {
2355 bool contains = reserved_region().contains(p);
2356 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2357 if (contains && available) {
2358 return true;
2359 } else {
2360 return false;
2361 }
2362 }
2363 #endif
2364
2365 bool G1CollectedHeap::obj_in_cs(oop obj) {
2366 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2367 return r != NULL && r->in_collection_set();
2368 }
2369
2370 // Iteration functions.
2371
2372 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2373
2374 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2375 ExtendedOopClosure* _cl;
2376 public:
2377 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2378 bool doHeapRegion(HeapRegion* r) {
2379 if (!r->is_continues_humongous()) {
2380 r->oop_iterate(_cl);
2381 }
2382 return false;
2383 }
2384 };
2385
2386 // Iterates an ObjectClosure over all objects within a HeapRegion.
2387
2388 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2389 ObjectClosure* _cl;
2390 public:
2391 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2392 bool doHeapRegion(HeapRegion* r) {
2393 if (!r->is_continues_humongous()) {
2394 r->object_iterate(_cl);
2395 }
2396 return false;
2397 }
2398 };
2399
2400 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2401 IterateObjectClosureRegionClosure blk(cl);
2402 heap_region_iterate(&blk);
2403 }
2404
2405 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2406 _hrm.iterate(cl);
2407 }
2408
2409 void
2410 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2411 uint worker_id,
2412 HeapRegionClaimer *hrclaimer,
2413 bool concurrent) const {
2414 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2415 }
2416
2417 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2418 _collection_set.iterate(cl);
2419 }
2420
2421 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2422 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2423 }
2424
2425 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2426 HeapRegion* result = _hrm.next_region_in_heap(from);
2427 while (result != NULL && result->is_pinned()) {
2428 result = _hrm.next_region_in_heap(result);
2429 }
2430 return result;
2431 }
2432
2433 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2434 HeapRegion* hr = heap_region_containing(addr);
2435 return hr->block_start(addr);
2436 }
2437
2438 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2439 HeapRegion* hr = heap_region_containing(addr);
2440 return hr->block_size(addr);
2441 }
2442
2443 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2444 HeapRegion* hr = heap_region_containing(addr);
2445 return hr->block_is_obj(addr);
2446 }
2447
2448 bool G1CollectedHeap::supports_tlab_allocation() const {
2449 return true;
2450 }
2451
2452 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2453 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2454 }
2455
2456 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2457 return _eden.length() * HeapRegion::GrainBytes;
2458 }
2459
2460 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2461 // must be equal to the humongous object limit.
2462 size_t G1CollectedHeap::max_tlab_size() const {
2463 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2464 }
2465
2466 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2467 AllocationContext_t context = AllocationContext::current();
2468 return _allocator->unsafe_max_tlab_alloc(context);
2469 }
2470
2471 size_t G1CollectedHeap::max_capacity() const {
2472 return _hrm.reserved().byte_size();
2473 }
2474
2475 jlong G1CollectedHeap::millis_since_last_gc() {
2476 // See the notes in GenCollectedHeap::millis_since_last_gc()
2477 // for more information about the implementation.
2478 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2479 _g1_policy->collection_pause_end_millis();
2480 if (ret_val < 0) {
2481 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2482 ". returning zero instead.", ret_val);
2483 return 0;
2484 }
2485 return ret_val;
2486 }
2487
2488 void G1CollectedHeap::prepare_for_verify() {
2489 _verifier->prepare_for_verify();
2490 }
2491
2492 void G1CollectedHeap::verify(VerifyOption vo) {
2493 _verifier->verify(vo);
2494 }
2495
2496 class PrintRegionClosure: public HeapRegionClosure {
2497 outputStream* _st;
2498 public:
2499 PrintRegionClosure(outputStream* st) : _st(st) {}
2500 bool doHeapRegion(HeapRegion* r) {
2501 r->print_on(_st);
2502 return false;
2503 }
2504 };
2505
2506 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2507 const HeapRegion* hr,
2508 const VerifyOption vo) const {
2509 switch (vo) {
2510 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2511 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2512 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2513 default: ShouldNotReachHere();
2514 }
2515 return false; // keep some compilers happy
2516 }
2517
2518 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2519 const VerifyOption vo) const {
2520 switch (vo) {
2521 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2522 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2523 case VerifyOption_G1UseMarkWord: {
2524 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2525 return !obj->is_gc_marked() && !hr->is_archive();
2526 }
2527 default: ShouldNotReachHere();
2528 }
2529 return false; // keep some compilers happy
2530 }
2531
2532 void G1CollectedHeap::print_heap_regions() const {
2533 Log(gc, heap, region) log;
2534 if (log.is_trace()) {
2535 ResourceMark rm;
2536 print_regions_on(log.trace_stream());
2537 }
2538 }
2539
2540 void G1CollectedHeap::print_on(outputStream* st) const {
2541 st->print(" %-20s", "garbage-first heap");
2542 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2543 capacity()/K, used_unlocked()/K);
2544 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2545 p2i(_hrm.reserved().start()),
2546 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2547 p2i(_hrm.reserved().end()));
2548 st->cr();
2549 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2550 uint young_regions = young_regions_count();
2551 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2552 (size_t) young_regions * HeapRegion::GrainBytes / K);
2553 uint survivor_regions = survivor_regions_count();
2554 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2555 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2556 st->cr();
2557 MetaspaceAux::print_on(st);
2558 }
2559
2560 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2561 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2562 "HS=humongous(starts), HC=humongous(continues), "
2563 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2564 "AC=allocation context, "
2565 "TAMS=top-at-mark-start (previous, next)");
2566 PrintRegionClosure blk(st);
2567 heap_region_iterate(&blk);
2568 }
2569
2570 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2571 print_on(st);
2572
2573 // Print the per-region information.
2574 print_regions_on(st);
2575 }
2576
2577 void G1CollectedHeap::print_on_error(outputStream* st) const {
2578 this->CollectedHeap::print_on_error(st);
2579
2580 if (_cm != NULL) {
2581 st->cr();
2582 _cm->print_on_error(st);
2583 }
2584 }
2585
2586 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2587 workers()->print_worker_threads_on(st);
2588 _cmThread->print_on(st);
2589 st->cr();
2590 _cm->print_worker_threads_on(st);
2591 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2592 if (G1StringDedup::is_enabled()) {
2593 G1StringDedup::print_worker_threads_on(st);
2594 }
2595 }
2596
2597 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2598 workers()->threads_do(tc);
2599 tc->do_thread(_cmThread);
2600 _cm->threads_do(tc);
2601 _cg1r->threads_do(tc); // also iterates over the sample thread
2602 if (G1StringDedup::is_enabled()) {
2603 G1StringDedup::threads_do(tc);
2604 }
2605 }
2606
2607 void G1CollectedHeap::print_tracing_info() const {
2608 g1_rem_set()->print_summary_info();
2609 concurrent_mark()->print_summary_info();
2610 }
2611
2612 #ifndef PRODUCT
2613 // Helpful for debugging RSet issues.
2614
2615 class PrintRSetsClosure : public HeapRegionClosure {
2616 private:
2617 const char* _msg;
2618 size_t _occupied_sum;
2619
2620 public:
2621 bool doHeapRegion(HeapRegion* r) {
2622 HeapRegionRemSet* hrrs = r->rem_set();
2623 size_t occupied = hrrs->occupied();
2624 _occupied_sum += occupied;
2625
2626 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2627 if (occupied == 0) {
2628 tty->print_cr(" RSet is empty");
2629 } else {
2630 hrrs->print();
2631 }
2632 tty->print_cr("----------");
2633 return false;
2634 }
2635
2636 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2637 tty->cr();
2638 tty->print_cr("========================================");
2639 tty->print_cr("%s", msg);
2640 tty->cr();
2641 }
2642
2643 ~PrintRSetsClosure() {
2644 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2645 tty->print_cr("========================================");
2646 tty->cr();
2647 }
2648 };
2649
2650 void G1CollectedHeap::print_cset_rsets() {
2651 PrintRSetsClosure cl("Printing CSet RSets");
2652 collection_set_iterate(&cl);
2653 }
2654
2655 void G1CollectedHeap::print_all_rsets() {
2656 PrintRSetsClosure cl("Printing All RSets");;
2657 heap_region_iterate(&cl);
2658 }
2659 #endif // PRODUCT
2660
2661 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2662
2663 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2664 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2665 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2666
2667 size_t eden_capacity_bytes =
2668 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2669
2670 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2671 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2672 eden_capacity_bytes, survivor_used_bytes, num_regions());
2673 }
2674
2675 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2676 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2677 stats->unused(), stats->used(), stats->region_end_waste(),
2678 stats->regions_filled(), stats->direct_allocated(),
2679 stats->failure_used(), stats->failure_waste());
2680 }
2681
2682 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2683 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2684 gc_tracer->report_gc_heap_summary(when, heap_summary);
2685
2686 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2687 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2688 }
2689
2690 G1CollectedHeap* G1CollectedHeap::heap() {
2691 CollectedHeap* heap = Universe::heap();
2692 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2693 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2694 return (G1CollectedHeap*)heap;
2695 }
2696
2697 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2698 // always_do_update_barrier = false;
2699 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2700 // Fill TLAB's and such
2701 accumulate_statistics_all_tlabs();
2702 ensure_parsability(true);
2703
2704 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2705 }
2706
2707 void G1CollectedHeap::gc_epilogue(bool full) {
2708 // we are at the end of the GC. Total collections has already been increased.
2709 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2710
2711 // FIXME: what is this about?
2712 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2713 // is set.
2714 #if defined(COMPILER2) || INCLUDE_JVMCI
2715 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2716 #endif
2717 // always_do_update_barrier = true;
2718
2719 resize_all_tlabs();
2720 allocation_context_stats().update(full);
2721
2722 // We have just completed a GC. Update the soft reference
2723 // policy with the new heap occupancy
2724 Universe::update_heap_info_at_gc();
2725 }
2726
2727 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2728 uint gc_count_before,
2729 bool* succeeded,
2730 GCCause::Cause gc_cause) {
2731 assert_heap_not_locked_and_not_at_safepoint();
2732 VM_G1IncCollectionPause op(gc_count_before,
2733 word_size,
2734 false, /* should_initiate_conc_mark */
2735 g1_policy()->max_pause_time_ms(),
2736 gc_cause);
2737
2738 op.set_allocation_context(AllocationContext::current());
2739 VMThread::execute(&op);
2740
2741 HeapWord* result = op.result();
2742 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2743 assert(result == NULL || ret_succeeded,
2744 "the result should be NULL if the VM did not succeed");
2745 *succeeded = ret_succeeded;
2746
2747 assert_heap_not_locked();
2748 return result;
2749 }
2750
2751 void
2752 G1CollectedHeap::doConcurrentMark() {
2753 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2754 if (!_cmThread->in_progress()) {
2755 _cmThread->set_started();
2756 CGC_lock->notify();
2757 }
2758 }
2759
2760 size_t G1CollectedHeap::pending_card_num() {
2761 size_t extra_cards = 0;
2762 JavaThread *curr = Threads::first();
2763 while (curr != NULL) {
2764 DirtyCardQueue& dcq = curr->dirty_card_queue();
2765 extra_cards += dcq.size();
2766 curr = curr->next();
2767 }
2768 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2769 size_t buffer_size = dcqs.buffer_size();
2770 size_t buffer_num = dcqs.completed_buffers_num();
2771
2772 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2773 // in bytes - not the number of 'entries'. We need to convert
2774 // into a number of cards.
2775 return (buffer_size * buffer_num + extra_cards) / oopSize;
2776 }
2777
2778 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2779 private:
2780 size_t _total_humongous;
2781 size_t _candidate_humongous;
2782
2783 DirtyCardQueue _dcq;
2784
2785 // We don't nominate objects with many remembered set entries, on
2786 // the assumption that such objects are likely still live.
2787 bool is_remset_small(HeapRegion* region) const {
2788 HeapRegionRemSet* const rset = region->rem_set();
2789 return G1EagerReclaimHumongousObjectsWithStaleRefs
2790 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2791 : rset->is_empty();
2792 }
2793
2794 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2795 assert(region->is_starts_humongous(), "Must start a humongous object");
2796
2797 oop obj = oop(region->bottom());
2798
2799 // Dead objects cannot be eager reclaim candidates. Due to class
2800 // unloading it is unsafe to query their classes so we return early.
2801 if (heap->is_obj_dead(obj, region)) {
2802 return false;
2803 }
2804
2805 // Candidate selection must satisfy the following constraints
2806 // while concurrent marking is in progress:
2807 //
2808 // * In order to maintain SATB invariants, an object must not be
2809 // reclaimed if it was allocated before the start of marking and
2810 // has not had its references scanned. Such an object must have
2811 // its references (including type metadata) scanned to ensure no
2812 // live objects are missed by the marking process. Objects
2813 // allocated after the start of concurrent marking don't need to
2814 // be scanned.
2815 //
2816 // * An object must not be reclaimed if it is on the concurrent
2817 // mark stack. Objects allocated after the start of concurrent
2818 // marking are never pushed on the mark stack.
2819 //
2820 // Nominating only objects allocated after the start of concurrent
2821 // marking is sufficient to meet both constraints. This may miss
2822 // some objects that satisfy the constraints, but the marking data
2823 // structures don't support efficiently performing the needed
2824 // additional tests or scrubbing of the mark stack.
2825 //
2826 // However, we presently only nominate is_typeArray() objects.
2827 // A humongous object containing references induces remembered
2828 // set entries on other regions. In order to reclaim such an
2829 // object, those remembered sets would need to be cleaned up.
2830 //
2831 // We also treat is_typeArray() objects specially, allowing them
2832 // to be reclaimed even if allocated before the start of
2833 // concurrent mark. For this we rely on mark stack insertion to
2834 // exclude is_typeArray() objects, preventing reclaiming an object
2835 // that is in the mark stack. We also rely on the metadata for
2836 // such objects to be built-in and so ensured to be kept live.
2837 // Frequent allocation and drop of large binary blobs is an
2838 // important use case for eager reclaim, and this special handling
2839 // may reduce needed headroom.
2840
2841 return obj->is_typeArray() && is_remset_small(region);
2842 }
2843
2844 public:
2845 RegisterHumongousWithInCSetFastTestClosure()
2846 : _total_humongous(0),
2847 _candidate_humongous(0),
2848 _dcq(&JavaThread::dirty_card_queue_set()) {
2849 }
2850
2851 virtual bool doHeapRegion(HeapRegion* r) {
2852 if (!r->is_starts_humongous()) {
2853 return false;
2854 }
2855 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2856
2857 bool is_candidate = humongous_region_is_candidate(g1h, r);
2858 uint rindex = r->hrm_index();
2859 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2860 if (is_candidate) {
2861 _candidate_humongous++;
2862 g1h->register_humongous_region_with_cset(rindex);
2863 // Is_candidate already filters out humongous object with large remembered sets.
2864 // If we have a humongous object with a few remembered sets, we simply flush these
2865 // remembered set entries into the DCQS. That will result in automatic
2866 // re-evaluation of their remembered set entries during the following evacuation
2867 // phase.
2868 if (!r->rem_set()->is_empty()) {
2869 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2870 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2871 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2872 HeapRegionRemSetIterator hrrs(r->rem_set());
2873 size_t card_index;
2874 while (hrrs.has_next(card_index)) {
2875 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2876 // The remembered set might contain references to already freed
2877 // regions. Filter out such entries to avoid failing card table
2878 // verification.
2879 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2880 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2881 *card_ptr = CardTableModRefBS::dirty_card_val();
2882 _dcq.enqueue(card_ptr);
2883 }
2884 }
2885 }
2886 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2887 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2888 hrrs.n_yielded(), r->rem_set()->occupied());
2889 r->rem_set()->clear_locked();
2890 }
2891 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2892 }
2893 _total_humongous++;
2894
2895 return false;
2896 }
2897
2898 size_t total_humongous() const { return _total_humongous; }
2899 size_t candidate_humongous() const { return _candidate_humongous; }
2900
2901 void flush_rem_set_entries() { _dcq.flush(); }
2902 };
2903
2904 void G1CollectedHeap::register_humongous_regions_with_cset() {
2905 if (!G1EagerReclaimHumongousObjects) {
2906 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2907 return;
2908 }
2909 double time = os::elapsed_counter();
2910
2911 // Collect reclaim candidate information and register candidates with cset.
2912 RegisterHumongousWithInCSetFastTestClosure cl;
2913 heap_region_iterate(&cl);
2914
2915 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2916 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2917 cl.total_humongous(),
2918 cl.candidate_humongous());
2919 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2920
2921 // Finally flush all remembered set entries to re-check into the global DCQS.
2922 cl.flush_rem_set_entries();
2923 }
2924
2925 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2926 public:
2927 bool doHeapRegion(HeapRegion* hr) {
2928 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2929 hr->verify_rem_set();
2930 }
2931 return false;
2932 }
2933 };
2934
2935 uint G1CollectedHeap::num_task_queues() const {
2936 return _task_queues->size();
2937 }
2938
2939 #if TASKQUEUE_STATS
2940 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2941 st->print_raw_cr("GC Task Stats");
2942 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2943 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2944 }
2945
2946 void G1CollectedHeap::print_taskqueue_stats() const {
2947 if (!log_is_enabled(Trace, gc, task, stats)) {
2948 return;
2949 }
2950 Log(gc, task, stats) log;
2951 ResourceMark rm;
2952 outputStream* st = log.trace_stream();
2953
2954 print_taskqueue_stats_hdr(st);
2955
2956 TaskQueueStats totals;
2957 const uint n = num_task_queues();
2958 for (uint i = 0; i < n; ++i) {
2959 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2960 totals += task_queue(i)->stats;
2961 }
2962 st->print_raw("tot "); totals.print(st); st->cr();
2963
2964 DEBUG_ONLY(totals.verify());
2965 }
2966
2967 void G1CollectedHeap::reset_taskqueue_stats() {
2968 const uint n = num_task_queues();
2969 for (uint i = 0; i < n; ++i) {
2970 task_queue(i)->stats.reset();
2971 }
2972 }
2973 #endif // TASKQUEUE_STATS
2974
2975 void G1CollectedHeap::wait_for_root_region_scanning() {
2976 double scan_wait_start = os::elapsedTime();
2977 // We have to wait until the CM threads finish scanning the
2978 // root regions as it's the only way to ensure that all the
2979 // objects on them have been correctly scanned before we start
2980 // moving them during the GC.
2981 bool waited = _cm->root_regions()->wait_until_scan_finished();
2982 double wait_time_ms = 0.0;
2983 if (waited) {
2984 double scan_wait_end = os::elapsedTime();
2985 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2986 }
2987 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2988 }
2989
2990 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2991 private:
2992 G1HRPrinter* _hr_printer;
2993 public:
2994 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2995
2996 virtual bool doHeapRegion(HeapRegion* r) {
2997 _hr_printer->cset(r);
2998 return false;
2999 }
3000 };
3001
3002 bool
3003 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3004 assert_at_safepoint(true /* should_be_vm_thread */);
3005 guarantee(!is_gc_active(), "collection is not reentrant");
3006
3007 if (GCLocker::check_active_before_gc()) {
3008 return false;
3009 }
3010
3011 _gc_timer_stw->register_gc_start();
3012
3013 GCIdMark gc_id_mark;
3014 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3015
3016 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3017 ResourceMark rm;
3018
3019 g1_policy()->note_gc_start();
3020
3021 wait_for_root_region_scanning();
3022
3023 print_heap_before_gc();
3024 print_heap_regions();
3025 trace_heap_before_gc(_gc_tracer_stw);
3026
3027 _verifier->verify_region_sets_optional();
3028 _verifier->verify_dirty_young_regions();
3029
3030 // We should not be doing initial mark unless the conc mark thread is running
3031 if (!_cmThread->should_terminate()) {
3032 // This call will decide whether this pause is an initial-mark
3033 // pause. If it is, during_initial_mark_pause() will return true
3034 // for the duration of this pause.
3035 g1_policy()->decide_on_conc_mark_initiation();
3036 }
3037
3038 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3039 assert(!collector_state()->during_initial_mark_pause() ||
3040 collector_state()->gcs_are_young(), "sanity");
3041
3042 // We also do not allow mixed GCs during marking.
3043 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3044
3045 // Record whether this pause is an initial mark. When the current
3046 // thread has completed its logging output and it's safe to signal
3047 // the CM thread, the flag's value in the policy has been reset.
3048 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3049
3050 // Inner scope for scope based logging, timers, and stats collection
3051 {
3052 EvacuationInfo evacuation_info;
3053
3054 if (collector_state()->during_initial_mark_pause()) {
3055 // We are about to start a marking cycle, so we increment the
3056 // full collection counter.
3057 increment_old_marking_cycles_started();
3058 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3059 }
3060
3061 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3062
3063 GCTraceCPUTime tcpu;
3064
3065 FormatBuffer<> gc_string("Pause ");
3066 if (collector_state()->during_initial_mark_pause()) {
3067 gc_string.append("Initial Mark");
3068 } else if (collector_state()->gcs_are_young()) {
3069 gc_string.append("Young");
3070 } else {
3071 gc_string.append("Mixed");
3072 }
3073 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3074
3075 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3076 workers()->active_workers(),
3077 Threads::number_of_non_daemon_threads());
3078 workers()->update_active_workers(active_workers);
3079 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3080
3081 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3082 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3083
3084 // If the secondary_free_list is not empty, append it to the
3085 // free_list. No need to wait for the cleanup operation to finish;
3086 // the region allocation code will check the secondary_free_list
3087 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3088 // set, skip this step so that the region allocation code has to
3089 // get entries from the secondary_free_list.
3090 if (!G1StressConcRegionFreeing) {
3091 append_secondary_free_list_if_not_empty_with_lock();
3092 }
3093
3094 G1HeapTransition heap_transition(this);
3095 size_t heap_used_bytes_before_gc = used();
3096
3097 // Don't dynamically change the number of GC threads this early. A value of
3098 // 0 is used to indicate serial work. When parallel work is done,
3099 // it will be set.
3100
3101 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3102 IsGCActiveMark x;
3103
3104 gc_prologue(false);
3105 increment_total_collections(false /* full gc */);
3106 increment_gc_time_stamp();
3107
3108 if (VerifyRememberedSets) {
3109 log_info(gc, verify)("[Verifying RemSets before GC]");
3110 VerifyRegionRemSetClosure v_cl;
3111 heap_region_iterate(&v_cl);
3112 }
3113
3114 _verifier->verify_before_gc();
3115
3116 _verifier->check_bitmaps("GC Start");
3117
3118 #if defined(COMPILER2) || INCLUDE_JVMCI
3119 DerivedPointerTable::clear();
3120 #endif
3121
3122 // Please see comment in g1CollectedHeap.hpp and
3123 // G1CollectedHeap::ref_processing_init() to see how
3124 // reference processing currently works in G1.
3125
3126 // Enable discovery in the STW reference processor
3127 if (g1_policy()->should_process_references()) {
3128 ref_processor_stw()->enable_discovery();
3129 } else {
3130 ref_processor_stw()->disable_discovery();
3131 }
3132
3133 {
3134 // We want to temporarily turn off discovery by the
3135 // CM ref processor, if necessary, and turn it back on
3136 // on again later if we do. Using a scoped
3137 // NoRefDiscovery object will do this.
3138 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3139
3140 // Forget the current alloc region (we might even choose it to be part
3141 // of the collection set!).
3142 _allocator->release_mutator_alloc_region();
3143
3144 // This timing is only used by the ergonomics to handle our pause target.
3145 // It is unclear why this should not include the full pause. We will
3146 // investigate this in CR 7178365.
3147 //
3148 // Preserving the old comment here if that helps the investigation:
3149 //
3150 // The elapsed time induced by the start time below deliberately elides
3151 // the possible verification above.
3152 double sample_start_time_sec = os::elapsedTime();
3153
3154 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3155
3156 if (collector_state()->during_initial_mark_pause()) {
3157 concurrent_mark()->checkpointRootsInitialPre();
3158 }
3159
3160 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3161
3162 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3163
3164 // Make sure the remembered sets are up to date. This needs to be
3165 // done before register_humongous_regions_with_cset(), because the
3166 // remembered sets are used there to choose eager reclaim candidates.
3167 // If the remembered sets are not up to date we might miss some
3168 // entries that need to be handled.
3169 g1_rem_set()->cleanupHRRS();
3170
3171 register_humongous_regions_with_cset();
3172
3173 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3174
3175 // We call this after finalize_cset() to
3176 // ensure that the CSet has been finalized.
3177 _cm->verify_no_cset_oops();
3178
3179 if (_hr_printer.is_active()) {
3180 G1PrintCollectionSetClosure cl(&_hr_printer);
3181 _collection_set.iterate(&cl);
3182 }
3183
3184 // Initialize the GC alloc regions.
3185 _allocator->init_gc_alloc_regions(evacuation_info);
3186
3187 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3188 pre_evacuate_collection_set();
3189
3190 // Actually do the work...
3191 evacuate_collection_set(evacuation_info, &per_thread_states);
3192
3193 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3194
3195 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3196 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3197
3198 eagerly_reclaim_humongous_regions();
3199
3200 record_obj_copy_mem_stats();
3201 _survivor_evac_stats.adjust_desired_plab_sz();
3202 _old_evac_stats.adjust_desired_plab_sz();
3203
3204 // Start a new incremental collection set for the next pause.
3205 collection_set()->start_incremental_building();
3206
3207 clear_cset_fast_test();
3208
3209 guarantee(_eden.length() == 0, "eden should have been cleared");
3210 g1_policy()->transfer_survivors_to_cset(survivor());
3211
3212 if (evacuation_failed()) {
3213 set_used(recalculate_used());
3214 if (_archive_allocator != NULL) {
3215 _archive_allocator->clear_used();
3216 }
3217 for (uint i = 0; i < ParallelGCThreads; i++) {
3218 if (_evacuation_failed_info_array[i].has_failed()) {
3219 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3220 }
3221 }
3222 } else {
3223 // The "used" of the the collection set have already been subtracted
3224 // when they were freed. Add in the bytes evacuated.
3225 increase_used(g1_policy()->bytes_copied_during_gc());
3226 }
3227
3228 if (collector_state()->during_initial_mark_pause()) {
3229 // We have to do this before we notify the CM threads that
3230 // they can start working to make sure that all the
3231 // appropriate initialization is done on the CM object.
3232 concurrent_mark()->checkpointRootsInitialPost();
3233 collector_state()->set_mark_in_progress(true);
3234 // Note that we don't actually trigger the CM thread at
3235 // this point. We do that later when we're sure that
3236 // the current thread has completed its logging output.
3237 }
3238
3239 allocate_dummy_regions();
3240
3241 _allocator->init_mutator_alloc_region();
3242
3243 {
3244 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3245 if (expand_bytes > 0) {
3246 size_t bytes_before = capacity();
3247 // No need for an ergo logging here,
3248 // expansion_amount() does this when it returns a value > 0.
3249 double expand_ms;
3250 if (!expand(expand_bytes, _workers, &expand_ms)) {
3251 // We failed to expand the heap. Cannot do anything about it.
3252 }
3253 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3254 }
3255 }
3256
3257 // We redo the verification but now wrt to the new CSet which
3258 // has just got initialized after the previous CSet was freed.
3259 _cm->verify_no_cset_oops();
3260
3261 // This timing is only used by the ergonomics to handle our pause target.
3262 // It is unclear why this should not include the full pause. We will
3263 // investigate this in CR 7178365.
3264 double sample_end_time_sec = os::elapsedTime();
3265 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3266 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3267 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3268
3269 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3270 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3271
3272 MemoryService::track_memory_usage();
3273
3274 // In prepare_for_verify() below we'll need to scan the deferred
3275 // update buffers to bring the RSets up-to-date if
3276 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3277 // the update buffers we'll probably need to scan cards on the
3278 // regions we just allocated to (i.e., the GC alloc
3279 // regions). However, during the last GC we called
3280 // set_saved_mark() on all the GC alloc regions, so card
3281 // scanning might skip the [saved_mark_word()...top()] area of
3282 // those regions (i.e., the area we allocated objects into
3283 // during the last GC). But it shouldn't. Given that
3284 // saved_mark_word() is conditional on whether the GC time stamp
3285 // on the region is current or not, by incrementing the GC time
3286 // stamp here we invalidate all the GC time stamps on all the
3287 // regions and saved_mark_word() will simply return top() for
3288 // all the regions. This is a nicer way of ensuring this rather
3289 // than iterating over the regions and fixing them. In fact, the
3290 // GC time stamp increment here also ensures that
3291 // saved_mark_word() will return top() between pauses, i.e.,
3292 // during concurrent refinement. So we don't need the
3293 // is_gc_active() check to decided which top to use when
3294 // scanning cards (see CR 7039627).
3295 increment_gc_time_stamp();
3296
3297 if (VerifyRememberedSets) {
3298 log_info(gc, verify)("[Verifying RemSets after GC]");
3299 VerifyRegionRemSetClosure v_cl;
3300 heap_region_iterate(&v_cl);
3301 }
3302
3303 _verifier->verify_after_gc();
3304 _verifier->check_bitmaps("GC End");
3305
3306 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3307 ref_processor_stw()->verify_no_references_recorded();
3308
3309 // CM reference discovery will be re-enabled if necessary.
3310 }
3311
3312 #ifdef TRACESPINNING
3313 ParallelTaskTerminator::print_termination_counts();
3314 #endif
3315
3316 gc_epilogue(false);
3317 }
3318
3319 // Print the remainder of the GC log output.
3320 if (evacuation_failed()) {
3321 log_info(gc)("To-space exhausted");
3322 }
3323
3324 g1_policy()->print_phases();
3325 heap_transition.print();
3326
3327 // It is not yet to safe to tell the concurrent mark to
3328 // start as we have some optional output below. We don't want the
3329 // output from the concurrent mark thread interfering with this
3330 // logging output either.
3331
3332 _hrm.verify_optional();
3333 _verifier->verify_region_sets_optional();
3334
3335 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3336 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3337
3338 print_heap_after_gc();
3339 print_heap_regions();
3340 trace_heap_after_gc(_gc_tracer_stw);
3341
3342 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3343 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3344 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3345 // before any GC notifications are raised.
3346 g1mm()->update_sizes();
3347
3348 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3349 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3350 _gc_timer_stw->register_gc_end();
3351 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3352 }
3353 // It should now be safe to tell the concurrent mark thread to start
3354 // without its logging output interfering with the logging output
3355 // that came from the pause.
3356
3357 if (should_start_conc_mark) {
3358 // CAUTION: after the doConcurrentMark() call below,
3359 // the concurrent marking thread(s) could be running
3360 // concurrently with us. Make sure that anything after
3361 // this point does not assume that we are the only GC thread
3362 // running. Note: of course, the actual marking work will
3363 // not start until the safepoint itself is released in
3364 // SuspendibleThreadSet::desynchronize().
3365 doConcurrentMark();
3366 }
3367
3368 return true;
3369 }
3370
3371 void G1CollectedHeap::remove_self_forwarding_pointers() {
3372 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3373 workers()->run_task(&rsfp_task);
3374 }
3375
3376 void G1CollectedHeap::restore_after_evac_failure() {
3377 double remove_self_forwards_start = os::elapsedTime();
3378
3379 remove_self_forwarding_pointers();
3380 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3381 _preserved_marks_set.restore(&task_executor);
3382
3383 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3384 }
3385
3386 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3387 if (!_evacuation_failed) {
3388 _evacuation_failed = true;
3389 }
3390
3391 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3392 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3393 }
3394
3395 bool G1ParEvacuateFollowersClosure::offer_termination() {
3396 G1ParScanThreadState* const pss = par_scan_state();
3397 start_term_time();
3398 const bool res = terminator()->offer_termination();
3399 end_term_time();
3400 return res;
3401 }
3402
3403 void G1ParEvacuateFollowersClosure::do_void() {
3404 G1ParScanThreadState* const pss = par_scan_state();
3405 pss->trim_queue();
3406 do {
3407 pss->steal_and_trim_queue(queues());
3408 } while (!offer_termination());
3409 }
3410
3411 class G1ParTask : public AbstractGangTask {
3412 protected:
3413 G1CollectedHeap* _g1h;
3414 G1ParScanThreadStateSet* _pss;
3415 RefToScanQueueSet* _queues;
3416 G1RootProcessor* _root_processor;
3417 ParallelTaskTerminator _terminator;
3418 uint _n_workers;
3419
3420 public:
3421 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3422 : AbstractGangTask("G1 collection"),
3423 _g1h(g1h),
3424 _pss(per_thread_states),
3425 _queues(task_queues),
3426 _root_processor(root_processor),
3427 _terminator(n_workers, _queues),
3428 _n_workers(n_workers)
3429 {}
3430
3431 void work(uint worker_id) {
3432 if (worker_id >= _n_workers) return; // no work needed this round
3433
3434 double start_sec = os::elapsedTime();
3435 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3436
3437 {
3438 ResourceMark rm;
3439 HandleMark hm;
3440
3441 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3442
3443 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3444 pss->set_ref_processor(rp);
3445
3446 double start_strong_roots_sec = os::elapsedTime();
3447
3448 _root_processor->evacuate_roots(pss->closures(), worker_id);
3449
3450 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3451
3452 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3453 // treating the nmethods visited to act as roots for concurrent marking.
3454 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3455 // objects copied by the current evacuation.
3456 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3457 pss->closures()->weak_codeblobs(),
3458 worker_id);
3459
3460 _pss->add_cards_scanned(worker_id, cards_scanned);
3461
3462 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3463
3464 double term_sec = 0.0;
3465 size_t evac_term_attempts = 0;
3466 {
3467 double start = os::elapsedTime();
3468 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3469 evac.do_void();
3470
3471 evac_term_attempts = evac.term_attempts();
3472 term_sec = evac.term_time();
3473 double elapsed_sec = os::elapsedTime() - start;
3474 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3475 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3476 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3477 }
3478
3479 assert(pss->queue_is_empty(), "should be empty");
3480
3481 if (log_is_enabled(Debug, gc, task, stats)) {
3482 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3483 size_t lab_waste;
3484 size_t lab_undo_waste;
3485 pss->waste(lab_waste, lab_undo_waste);
3486 _g1h->print_termination_stats(worker_id,
3487 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3488 strong_roots_sec * 1000.0, /* strong roots time */
3489 term_sec * 1000.0, /* evac term time */
3490 evac_term_attempts, /* evac term attempts */
3491 lab_waste, /* alloc buffer waste */
3492 lab_undo_waste /* undo waste */
3493 );
3494 }
3495
3496 // Close the inner scope so that the ResourceMark and HandleMark
3497 // destructors are executed here and are included as part of the
3498 // "GC Worker Time".
3499 }
3500 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3501 }
3502 };
3503
3504 void G1CollectedHeap::print_termination_stats_hdr() {
3505 log_debug(gc, task, stats)("GC Termination Stats");
3506 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3507 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3508 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3509 }
3510
3511 void G1CollectedHeap::print_termination_stats(uint worker_id,
3512 double elapsed_ms,
3513 double strong_roots_ms,
3514 double term_ms,
3515 size_t term_attempts,
3516 size_t alloc_buffer_waste,
3517 size_t undo_waste) const {
3518 log_debug(gc, task, stats)
3519 ("%3d %9.2f %9.2f %6.2f "
3520 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3521 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3522 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3523 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3524 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3525 alloc_buffer_waste * HeapWordSize / K,
3526 undo_waste * HeapWordSize / K);
3527 }
3528
3529 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3530 private:
3531 BoolObjectClosure* _is_alive;
3532 int _initial_string_table_size;
3533 int _initial_symbol_table_size;
3534
3535 bool _process_strings;
3536 int _strings_processed;
3537 int _strings_removed;
3538
3539 bool _process_symbols;
3540 int _symbols_processed;
3541 int _symbols_removed;
3542
3543 public:
3544 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3545 AbstractGangTask("String/Symbol Unlinking"),
3546 _is_alive(is_alive),
3547 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3548 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3549
3550 _initial_string_table_size = StringTable::the_table()->table_size();
3551 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3552 if (process_strings) {
3553 StringTable::clear_parallel_claimed_index();
3554 }
3555 if (process_symbols) {
3556 SymbolTable::clear_parallel_claimed_index();
3557 }
3558 }
3559
3560 ~G1StringSymbolTableUnlinkTask() {
3561 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3562 "claim value %d after unlink less than initial string table size %d",
3563 StringTable::parallel_claimed_index(), _initial_string_table_size);
3564 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3565 "claim value %d after unlink less than initial symbol table size %d",
3566 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3567
3568 log_info(gc, stringtable)(
3569 "Cleaned string and symbol table, "
3570 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3571 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3572 strings_processed(), strings_removed(),
3573 symbols_processed(), symbols_removed());
3574 }
3575
3576 void work(uint worker_id) {
3577 int strings_processed = 0;
3578 int strings_removed = 0;
3579 int symbols_processed = 0;
3580 int symbols_removed = 0;
3581 if (_process_strings) {
3582 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3583 Atomic::add(strings_processed, &_strings_processed);
3584 Atomic::add(strings_removed, &_strings_removed);
3585 }
3586 if (_process_symbols) {
3587 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3588 Atomic::add(symbols_processed, &_symbols_processed);
3589 Atomic::add(symbols_removed, &_symbols_removed);
3590 }
3591 }
3592
3593 size_t strings_processed() const { return (size_t)_strings_processed; }
3594 size_t strings_removed() const { return (size_t)_strings_removed; }
3595
3596 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3597 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3598 };
3599
3600 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3601 private:
3602 static Monitor* _lock;
3603
3604 BoolObjectClosure* const _is_alive;
3605 const bool _unloading_occurred;
3606 const uint _num_workers;
3607
3608 // Variables used to claim nmethods.
3609 CompiledMethod* _first_nmethod;
3610 volatile CompiledMethod* _claimed_nmethod;
3611
3612 // The list of nmethods that need to be processed by the second pass.
3613 volatile CompiledMethod* _postponed_list;
3614 volatile uint _num_entered_barrier;
3615
3616 public:
3617 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3618 _is_alive(is_alive),
3619 _unloading_occurred(unloading_occurred),
3620 _num_workers(num_workers),
3621 _first_nmethod(NULL),
3622 _claimed_nmethod(NULL),
3623 _postponed_list(NULL),
3624 _num_entered_barrier(0)
3625 {
3626 CompiledMethod::increase_unloading_clock();
3627 // Get first alive nmethod
3628 CompiledMethodIterator iter = CompiledMethodIterator();
3629 if(iter.next_alive()) {
3630 _first_nmethod = iter.method();
3631 }
3632 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3633 }
3634
3635 ~G1CodeCacheUnloadingTask() {
3636 CodeCache::verify_clean_inline_caches();
3637
3638 CodeCache::set_needs_cache_clean(false);
3639 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3640
3641 CodeCache::verify_icholder_relocations();
3642 }
3643
3644 private:
3645 void add_to_postponed_list(CompiledMethod* nm) {
3646 CompiledMethod* old;
3647 do {
3648 old = (CompiledMethod*)_postponed_list;
3649 nm->set_unloading_next(old);
3650 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3651 }
3652
3653 void clean_nmethod(CompiledMethod* nm) {
3654 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3655
3656 if (postponed) {
3657 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3658 add_to_postponed_list(nm);
3659 }
3660
3661 // Mark that this thread has been cleaned/unloaded.
3662 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3663 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3664 }
3665
3666 void clean_nmethod_postponed(CompiledMethod* nm) {
3667 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3668 }
3669
3670 static const int MaxClaimNmethods = 16;
3671
3672 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3673 CompiledMethod* first;
3674 CompiledMethodIterator last;
3675
3676 do {
3677 *num_claimed_nmethods = 0;
3678
3679 first = (CompiledMethod*)_claimed_nmethod;
3680 last = CompiledMethodIterator(first);
3681
3682 if (first != NULL) {
3683
3684 for (int i = 0; i < MaxClaimNmethods; i++) {
3685 if (!last.next_alive()) {
3686 break;
3687 }
3688 claimed_nmethods[i] = last.method();
3689 (*num_claimed_nmethods)++;
3690 }
3691 }
3692
3693 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3694 }
3695
3696 CompiledMethod* claim_postponed_nmethod() {
3697 CompiledMethod* claim;
3698 CompiledMethod* next;
3699
3700 do {
3701 claim = (CompiledMethod*)_postponed_list;
3702 if (claim == NULL) {
3703 return NULL;
3704 }
3705
3706 next = claim->unloading_next();
3707
3708 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3709
3710 return claim;
3711 }
3712
3713 public:
3714 // Mark that we're done with the first pass of nmethod cleaning.
3715 void barrier_mark(uint worker_id) {
3716 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3717 _num_entered_barrier++;
3718 if (_num_entered_barrier == _num_workers) {
3719 ml.notify_all();
3720 }
3721 }
3722
3723 // See if we have to wait for the other workers to
3724 // finish their first-pass nmethod cleaning work.
3725 void barrier_wait(uint worker_id) {
3726 if (_num_entered_barrier < _num_workers) {
3727 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3728 while (_num_entered_barrier < _num_workers) {
3729 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3730 }
3731 }
3732 }
3733
3734 // Cleaning and unloading of nmethods. Some work has to be postponed
3735 // to the second pass, when we know which nmethods survive.
3736 void work_first_pass(uint worker_id) {
3737 // The first nmethods is claimed by the first worker.
3738 if (worker_id == 0 && _first_nmethod != NULL) {
3739 clean_nmethod(_first_nmethod);
3740 _first_nmethod = NULL;
3741 }
3742
3743 int num_claimed_nmethods;
3744 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3745
3746 while (true) {
3747 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3748
3749 if (num_claimed_nmethods == 0) {
3750 break;
3751 }
3752
3753 for (int i = 0; i < num_claimed_nmethods; i++) {
3754 clean_nmethod(claimed_nmethods[i]);
3755 }
3756 }
3757 }
3758
3759 void work_second_pass(uint worker_id) {
3760 CompiledMethod* nm;
3761 // Take care of postponed nmethods.
3762 while ((nm = claim_postponed_nmethod()) != NULL) {
3763 clean_nmethod_postponed(nm);
3764 }
3765 }
3766 };
3767
3768 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3769
3770 class G1KlassCleaningTask : public StackObj {
3771 BoolObjectClosure* _is_alive;
3772 volatile jint _clean_klass_tree_claimed;
3773 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3774
3775 public:
3776 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3777 _is_alive(is_alive),
3778 _clean_klass_tree_claimed(0),
3779 _klass_iterator() {
3780 }
3781
3782 private:
3783 bool claim_clean_klass_tree_task() {
3784 if (_clean_klass_tree_claimed) {
3785 return false;
3786 }
3787
3788 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3789 }
3790
3791 InstanceKlass* claim_next_klass() {
3792 Klass* klass;
3793 do {
3794 klass =_klass_iterator.next_klass();
3795 } while (klass != NULL && !klass->is_instance_klass());
3796
3797 // this can be null so don't call InstanceKlass::cast
3798 return static_cast<InstanceKlass*>(klass);
3799 }
3800
3801 public:
3802
3803 void clean_klass(InstanceKlass* ik) {
3804 ik->clean_weak_instanceklass_links(_is_alive);
3805 }
3806
3807 void work() {
3808 ResourceMark rm;
3809
3810 // One worker will clean the subklass/sibling klass tree.
3811 if (claim_clean_klass_tree_task()) {
3812 Klass::clean_subklass_tree(_is_alive);
3813 }
3814
3815 // All workers will help cleaning the classes,
3816 InstanceKlass* klass;
3817 while ((klass = claim_next_klass()) != NULL) {
3818 clean_klass(klass);
3819 }
3820 }
3821 };
3822
3823 // To minimize the remark pause times, the tasks below are done in parallel.
3824 class G1ParallelCleaningTask : public AbstractGangTask {
3825 private:
3826 G1StringSymbolTableUnlinkTask _string_symbol_task;
3827 G1CodeCacheUnloadingTask _code_cache_task;
3828 G1KlassCleaningTask _klass_cleaning_task;
3829
3830 public:
3831 // The constructor is run in the VMThread.
3832 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
3833 AbstractGangTask("Parallel Cleaning"),
3834 _string_symbol_task(is_alive, process_strings, process_symbols),
3835 _code_cache_task(num_workers, is_alive, unloading_occurred),
3836 _klass_cleaning_task(is_alive) {
3837 }
3838
3839 // The parallel work done by all worker threads.
3840 void work(uint worker_id) {
3841 // Do first pass of code cache cleaning.
3842 _code_cache_task.work_first_pass(worker_id);
3843
3844 // Let the threads mark that the first pass is done.
3845 _code_cache_task.barrier_mark(worker_id);
3846
3847 // Clean the Strings and Symbols.
3848 _string_symbol_task.work(worker_id);
3849
3850 // Wait for all workers to finish the first code cache cleaning pass.
3851 _code_cache_task.barrier_wait(worker_id);
3852
3853 // Do the second code cache cleaning work, which realize on
3854 // the liveness information gathered during the first pass.
3855 _code_cache_task.work_second_pass(worker_id);
3856
3857 // Clean all klasses that were not unloaded.
3858 _klass_cleaning_task.work();
3859 }
3860 };
3861
3862
3863 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
3864 bool process_strings,
3865 bool process_symbols,
3866 bool class_unloading_occurred) {
3867 uint n_workers = workers()->active_workers();
3868
3869 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
3870 n_workers, class_unloading_occurred);
3871 workers()->run_task(&g1_unlink_task);
3872 }
3873
3874 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
3875 bool process_strings, bool process_symbols) {
3876 { // Timing scope
3877 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
3878 workers()->run_task(&g1_unlink_task);
3879 }
3880 }
3881
3882 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3883 private:
3884 DirtyCardQueueSet* _queue;
3885 G1CollectedHeap* _g1h;
3886 public:
3887 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3888 _queue(queue), _g1h(g1h) { }
3889
3890 virtual void work(uint worker_id) {
3891 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3892 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3893
3894 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3895 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3896
3897 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3898 }
3899 };
3900
3901 void G1CollectedHeap::redirty_logged_cards() {
3902 double redirty_logged_cards_start = os::elapsedTime();
3903
3904 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3905 dirty_card_queue_set().reset_for_par_iteration();
3906 workers()->run_task(&redirty_task);
3907
3908 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3909 dcq.merge_bufferlists(&dirty_card_queue_set());
3910 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3911
3912 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3913 }
3914
3915 // Weak Reference Processing support
3916
3917 // An always "is_alive" closure that is used to preserve referents.
3918 // If the object is non-null then it's alive. Used in the preservation
3919 // of referent objects that are pointed to by reference objects
3920 // discovered by the CM ref processor.
3921 class G1AlwaysAliveClosure: public BoolObjectClosure {
3922 G1CollectedHeap* _g1;
3923 public:
3924 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3925 bool do_object_b(oop p) {
3926 if (p != NULL) {
3927 return true;
3928 }
3929 return false;
3930 }
3931 };
3932
3933 bool G1STWIsAliveClosure::do_object_b(oop p) {
3934 // An object is reachable if it is outside the collection set,
3935 // or is inside and copied.
3936 return !_g1->is_in_cset(p) || p->is_forwarded();
3937 }
3938
3939 // Non Copying Keep Alive closure
3940 class G1KeepAliveClosure: public OopClosure {
3941 G1CollectedHeap* _g1;
3942 public:
3943 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3944 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3945 void do_oop(oop* p) {
3946 oop obj = *p;
3947 assert(obj != NULL, "the caller should have filtered out NULL values");
3948
3949 const InCSetState cset_state = _g1->in_cset_state(obj);
3950 if (!cset_state.is_in_cset_or_humongous()) {
3951 return;
3952 }
3953 if (cset_state.is_in_cset()) {
3954 assert( obj->is_forwarded(), "invariant" );
3955 *p = obj->forwardee();
3956 } else {
3957 assert(!obj->is_forwarded(), "invariant" );
3958 assert(cset_state.is_humongous(),
3959 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3960 _g1->set_humongous_is_live(obj);
3961 }
3962 }
3963 };
3964
3965 // Copying Keep Alive closure - can be called from both
3966 // serial and parallel code as long as different worker
3967 // threads utilize different G1ParScanThreadState instances
3968 // and different queues.
3969
3970 class G1CopyingKeepAliveClosure: public OopClosure {
3971 G1CollectedHeap* _g1h;
3972 OopClosure* _copy_non_heap_obj_cl;
3973 G1ParScanThreadState* _par_scan_state;
3974
3975 public:
3976 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3977 OopClosure* non_heap_obj_cl,
3978 G1ParScanThreadState* pss):
3979 _g1h(g1h),
3980 _copy_non_heap_obj_cl(non_heap_obj_cl),
3981 _par_scan_state(pss)
3982 {}
3983
3984 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3985 virtual void do_oop( oop* p) { do_oop_work(p); }
3986
3987 template <class T> void do_oop_work(T* p) {
3988 oop obj = oopDesc::load_decode_heap_oop(p);
3989
3990 if (_g1h->is_in_cset_or_humongous(obj)) {
3991 // If the referent object has been forwarded (either copied
3992 // to a new location or to itself in the event of an
3993 // evacuation failure) then we need to update the reference
3994 // field and, if both reference and referent are in the G1
3995 // heap, update the RSet for the referent.
3996 //
3997 // If the referent has not been forwarded then we have to keep
3998 // it alive by policy. Therefore we have copy the referent.
3999 //
4000 // If the reference field is in the G1 heap then we can push
4001 // on the PSS queue. When the queue is drained (after each
4002 // phase of reference processing) the object and it's followers
4003 // will be copied, the reference field set to point to the
4004 // new location, and the RSet updated. Otherwise we need to
4005 // use the the non-heap or metadata closures directly to copy
4006 // the referent object and update the pointer, while avoiding
4007 // updating the RSet.
4008
4009 if (_g1h->is_in_g1_reserved(p)) {
4010 _par_scan_state->push_on_queue(p);
4011 } else {
4012 assert(!Metaspace::contains((const void*)p),
4013 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4014 _copy_non_heap_obj_cl->do_oop(p);
4015 }
4016 }
4017 }
4018 };
4019
4020 // Serial drain queue closure. Called as the 'complete_gc'
4021 // closure for each discovered list in some of the
4022 // reference processing phases.
4023
4024 class G1STWDrainQueueClosure: public VoidClosure {
4025 protected:
4026 G1CollectedHeap* _g1h;
4027 G1ParScanThreadState* _par_scan_state;
4028
4029 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4030
4031 public:
4032 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4033 _g1h(g1h),
4034 _par_scan_state(pss)
4035 { }
4036
4037 void do_void() {
4038 G1ParScanThreadState* const pss = par_scan_state();
4039 pss->trim_queue();
4040 }
4041 };
4042
4043 // Parallel Reference Processing closures
4044
4045 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4046 // processing during G1 evacuation pauses.
4047
4048 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4049 private:
4050 G1CollectedHeap* _g1h;
4051 G1ParScanThreadStateSet* _pss;
4052 RefToScanQueueSet* _queues;
4053 WorkGang* _workers;
4054 uint _active_workers;
4055
4056 public:
4057 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4058 G1ParScanThreadStateSet* per_thread_states,
4059 WorkGang* workers,
4060 RefToScanQueueSet *task_queues,
4061 uint n_workers) :
4062 _g1h(g1h),
4063 _pss(per_thread_states),
4064 _queues(task_queues),
4065 _workers(workers),
4066 _active_workers(n_workers)
4067 {
4068 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4069 }
4070
4071 // Executes the given task using concurrent marking worker threads.
4072 virtual void execute(ProcessTask& task);
4073 virtual void execute(EnqueueTask& task);
4074 };
4075
4076 // Gang task for possibly parallel reference processing
4077
4078 class G1STWRefProcTaskProxy: public AbstractGangTask {
4079 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4080 ProcessTask& _proc_task;
4081 G1CollectedHeap* _g1h;
4082 G1ParScanThreadStateSet* _pss;
4083 RefToScanQueueSet* _task_queues;
4084 ParallelTaskTerminator* _terminator;
4085
4086 public:
4087 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4088 G1CollectedHeap* g1h,
4089 G1ParScanThreadStateSet* per_thread_states,
4090 RefToScanQueueSet *task_queues,
4091 ParallelTaskTerminator* terminator) :
4092 AbstractGangTask("Process reference objects in parallel"),
4093 _proc_task(proc_task),
4094 _g1h(g1h),
4095 _pss(per_thread_states),
4096 _task_queues(task_queues),
4097 _terminator(terminator)
4098 {}
4099
4100 virtual void work(uint worker_id) {
4101 // The reference processing task executed by a single worker.
4102 ResourceMark rm;
4103 HandleMark hm;
4104
4105 G1STWIsAliveClosure is_alive(_g1h);
4106
4107 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4108 pss->set_ref_processor(NULL);
4109
4110 // Keep alive closure.
4111 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4112
4113 // Complete GC closure
4114 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4115
4116 // Call the reference processing task's work routine.
4117 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4118
4119 // Note we cannot assert that the refs array is empty here as not all
4120 // of the processing tasks (specifically phase2 - pp2_work) execute
4121 // the complete_gc closure (which ordinarily would drain the queue) so
4122 // the queue may not be empty.
4123 }
4124 };
4125
4126 // Driver routine for parallel reference processing.
4127 // Creates an instance of the ref processing gang
4128 // task and has the worker threads execute it.
4129 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4130 assert(_workers != NULL, "Need parallel worker threads.");
4131
4132 ParallelTaskTerminator terminator(_active_workers, _queues);
4133 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4134
4135 _workers->run_task(&proc_task_proxy);
4136 }
4137
4138 // Gang task for parallel reference enqueueing.
4139
4140 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4141 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4142 EnqueueTask& _enq_task;
4143
4144 public:
4145 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4146 AbstractGangTask("Enqueue reference objects in parallel"),
4147 _enq_task(enq_task)
4148 { }
4149
4150 virtual void work(uint worker_id) {
4151 _enq_task.work(worker_id);
4152 }
4153 };
4154
4155 // Driver routine for parallel reference enqueueing.
4156 // Creates an instance of the ref enqueueing gang
4157 // task and has the worker threads execute it.
4158
4159 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4160 assert(_workers != NULL, "Need parallel worker threads.");
4161
4162 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4163
4164 _workers->run_task(&enq_task_proxy);
4165 }
4166
4167 // End of weak reference support closures
4168
4169 // Abstract task used to preserve (i.e. copy) any referent objects
4170 // that are in the collection set and are pointed to by reference
4171 // objects discovered by the CM ref processor.
4172
4173 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4174 protected:
4175 G1CollectedHeap* _g1h;
4176 G1ParScanThreadStateSet* _pss;
4177 RefToScanQueueSet* _queues;
4178 ParallelTaskTerminator _terminator;
4179 uint _n_workers;
4180
4181 public:
4182 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4183 AbstractGangTask("ParPreserveCMReferents"),
4184 _g1h(g1h),
4185 _pss(per_thread_states),
4186 _queues(task_queues),
4187 _terminator(workers, _queues),
4188 _n_workers(workers)
4189 {
4190 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4191 }
4192
4193 void work(uint worker_id) {
4194 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4195
4196 ResourceMark rm;
4197 HandleMark hm;
4198
4199 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4200 pss->set_ref_processor(NULL);
4201 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4202
4203 // Is alive closure
4204 G1AlwaysAliveClosure always_alive(_g1h);
4205
4206 // Copying keep alive closure. Applied to referent objects that need
4207 // to be copied.
4208 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4209
4210 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4211
4212 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4213 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4214
4215 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4216 // So this must be true - but assert just in case someone decides to
4217 // change the worker ids.
4218 assert(worker_id < limit, "sanity");
4219 assert(!rp->discovery_is_atomic(), "check this code");
4220
4221 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4222 for (uint idx = worker_id; idx < limit; idx += stride) {
4223 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4224
4225 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4226 while (iter.has_next()) {
4227 // Since discovery is not atomic for the CM ref processor, we
4228 // can see some null referent objects.
4229 iter.load_ptrs(DEBUG_ONLY(true));
4230 oop ref = iter.obj();
4231
4232 // This will filter nulls.
4233 if (iter.is_referent_alive()) {
4234 iter.make_referent_alive();
4235 }
4236 iter.move_to_next();
4237 }
4238 }
4239
4240 // Drain the queue - which may cause stealing
4241 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4242 drain_queue.do_void();
4243 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4244 assert(pss->queue_is_empty(), "should be");
4245 }
4246 };
4247
4248 void G1CollectedHeap::process_weak_jni_handles() {
4249 double ref_proc_start = os::elapsedTime();
4250
4251 G1STWIsAliveClosure is_alive(this);
4252 G1KeepAliveClosure keep_alive(this);
4253 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4254
4255 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4256 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4257 }
4258
4259 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4260 // Any reference objects, in the collection set, that were 'discovered'
4261 // by the CM ref processor should have already been copied (either by
4262 // applying the external root copy closure to the discovered lists, or
4263 // by following an RSet entry).
4264 //
4265 // But some of the referents, that are in the collection set, that these
4266 // reference objects point to may not have been copied: the STW ref
4267 // processor would have seen that the reference object had already
4268 // been 'discovered' and would have skipped discovering the reference,
4269 // but would not have treated the reference object as a regular oop.
4270 // As a result the copy closure would not have been applied to the
4271 // referent object.
4272 //
4273 // We need to explicitly copy these referent objects - the references
4274 // will be processed at the end of remarking.
4275 //
4276 // We also need to do this copying before we process the reference
4277 // objects discovered by the STW ref processor in case one of these
4278 // referents points to another object which is also referenced by an
4279 // object discovered by the STW ref processor.
4280 double preserve_cm_referents_time = 0.0;
4281
4282 // To avoid spawning task when there is no work to do, check that
4283 // a concurrent cycle is active and that some references have been
4284 // discovered.
4285 if (concurrent_mark()->cmThread()->during_cycle() &&
4286 ref_processor_cm()->has_discovered_references()) {
4287 double preserve_cm_referents_start = os::elapsedTime();
4288 uint no_of_gc_workers = workers()->active_workers();
4289 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4290 per_thread_states,
4291 no_of_gc_workers,
4292 _task_queues);
4293 workers()->run_task(&keep_cm_referents);
4294 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4295 }
4296
4297 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4298 }
4299
4300 // Weak Reference processing during an evacuation pause (part 1).
4301 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4302 double ref_proc_start = os::elapsedTime();
4303
4304 ReferenceProcessor* rp = _ref_processor_stw;
4305 assert(rp->discovery_enabled(), "should have been enabled");
4306
4307 // Closure to test whether a referent is alive.
4308 G1STWIsAliveClosure is_alive(this);
4309
4310 // Even when parallel reference processing is enabled, the processing
4311 // of JNI refs is serial and performed serially by the current thread
4312 // rather than by a worker. The following PSS will be used for processing
4313 // JNI refs.
4314
4315 // Use only a single queue for this PSS.
4316 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4317 pss->set_ref_processor(NULL);
4318 assert(pss->queue_is_empty(), "pre-condition");
4319
4320 // Keep alive closure.
4321 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4322
4323 // Serial Complete GC closure
4324 G1STWDrainQueueClosure drain_queue(this, pss);
4325
4326 // Setup the soft refs policy...
4327 rp->setup_policy(false);
4328
4329 ReferenceProcessorStats stats;
4330 if (!rp->processing_is_mt()) {
4331 // Serial reference processing...
4332 stats = rp->process_discovered_references(&is_alive,
4333 &keep_alive,
4334 &drain_queue,
4335 NULL,
4336 _gc_timer_stw);
4337 } else {
4338 uint no_of_gc_workers = workers()->active_workers();
4339
4340 // Parallel reference processing
4341 assert(no_of_gc_workers <= rp->max_num_q(),
4342 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4343 no_of_gc_workers, rp->max_num_q());
4344
4345 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4346 stats = rp->process_discovered_references(&is_alive,
4347 &keep_alive,
4348 &drain_queue,
4349 &par_task_executor,
4350 _gc_timer_stw);
4351 }
4352
4353 _gc_tracer_stw->report_gc_reference_stats(stats);
4354
4355 // We have completed copying any necessary live referent objects.
4356 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4357
4358 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4359 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4360 }
4361
4362 // Weak Reference processing during an evacuation pause (part 2).
4363 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4364 double ref_enq_start = os::elapsedTime();
4365
4366 ReferenceProcessor* rp = _ref_processor_stw;
4367 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4368
4369 // Now enqueue any remaining on the discovered lists on to
4370 // the pending list.
4371 if (!rp->processing_is_mt()) {
4372 // Serial reference processing...
4373 rp->enqueue_discovered_references();
4374 } else {
4375 // Parallel reference enqueueing
4376
4377 uint n_workers = workers()->active_workers();
4378
4379 assert(n_workers <= rp->max_num_q(),
4380 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4381 n_workers, rp->max_num_q());
4382
4383 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4384 rp->enqueue_discovered_references(&par_task_executor);
4385 }
4386
4387 rp->verify_no_references_recorded();
4388 assert(!rp->discovery_enabled(), "should have been disabled");
4389
4390 // FIXME
4391 // CM's reference processing also cleans up the string and symbol tables.
4392 // Should we do that here also? We could, but it is a serial operation
4393 // and could significantly increase the pause time.
4394
4395 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4396 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4397 }
4398
4399 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4400 double merge_pss_time_start = os::elapsedTime();
4401 per_thread_states->flush();
4402 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4403 }
4404
4405 void G1CollectedHeap::pre_evacuate_collection_set() {
4406 _expand_heap_after_alloc_failure = true;
4407 _evacuation_failed = false;
4408
4409 // Disable the hot card cache.
4410 _hot_card_cache->reset_hot_cache_claimed_index();
4411 _hot_card_cache->set_use_cache(false);
4412
4413 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4414 _preserved_marks_set.assert_empty();
4415 }
4416
4417 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4418 // Should G1EvacuationFailureALot be in effect for this GC?
4419 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4420
4421 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4422
4423 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4424
4425 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4426 if (collector_state()->during_initial_mark_pause()) {
4427 double start_clear_claimed_marks = os::elapsedTime();
4428
4429 ClassLoaderDataGraph::clear_claimed_marks();
4430
4431 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4432 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4433 }
4434
4435 double start_par_time_sec = os::elapsedTime();
4436 double end_par_time_sec;
4437
4438 {
4439 const uint n_workers = workers()->active_workers();
4440 G1RootProcessor root_processor(this, n_workers);
4441 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4442
4443 print_termination_stats_hdr();
4444
4445 workers()->run_task(&g1_par_task);
4446 end_par_time_sec = os::elapsedTime();
4447
4448 // Closing the inner scope will execute the destructor
4449 // for the G1RootProcessor object. We record the current
4450 // elapsed time before closing the scope so that time
4451 // taken for the destructor is NOT included in the
4452 // reported parallel time.
4453 }
4454
4455 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4456 phase_times->record_par_time(par_time_ms);
4457
4458 double code_root_fixup_time_ms =
4459 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4460 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4461 }
4462
4463 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4464 // Process any discovered reference objects - we have
4465 // to do this _before_ we retire the GC alloc regions
4466 // as we may have to copy some 'reachable' referent
4467 // objects (and their reachable sub-graphs) that were
4468 // not copied during the pause.
4469 if (g1_policy()->should_process_references()) {
4470 preserve_cm_referents(per_thread_states);
4471 process_discovered_references(per_thread_states);
4472 } else {
4473 ref_processor_stw()->verify_no_references_recorded();
4474 process_weak_jni_handles();
4475 }
4476
4477 if (G1StringDedup::is_enabled()) {
4478 double fixup_start = os::elapsedTime();
4479
4480 G1STWIsAliveClosure is_alive(this);
4481 G1KeepAliveClosure keep_alive(this);
4482 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4483
4484 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4485 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4486 }
4487
4488 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4489
4490 if (evacuation_failed()) {
4491 restore_after_evac_failure();
4492
4493 // Reset the G1EvacuationFailureALot counters and flags
4494 // Note: the values are reset only when an actual
4495 // evacuation failure occurs.
4496 NOT_PRODUCT(reset_evacuation_should_fail();)
4497 }
4498
4499 _preserved_marks_set.assert_empty();
4500
4501 // Enqueue any remaining references remaining on the STW
4502 // reference processor's discovered lists. We need to do
4503 // this after the card table is cleaned (and verified) as
4504 // the act of enqueueing entries on to the pending list
4505 // will log these updates (and dirty their associated
4506 // cards). We need these updates logged to update any
4507 // RSets.
4508 if (g1_policy()->should_process_references()) {
4509 enqueue_discovered_references(per_thread_states);
4510 } else {
4511 g1_policy()->phase_times()->record_ref_enq_time(0);
4512 }
4513
4514 _allocator->release_gc_alloc_regions(evacuation_info);
4515
4516 merge_per_thread_state_info(per_thread_states);
4517
4518 // Reset and re-enable the hot card cache.
4519 // Note the counts for the cards in the regions in the
4520 // collection set are reset when the collection set is freed.
4521 _hot_card_cache->reset_hot_cache();
4522 _hot_card_cache->set_use_cache(true);
4523
4524 purge_code_root_memory();
4525
4526 redirty_logged_cards();
4527 #if defined(COMPILER2) || INCLUDE_JVMCI
4528 DerivedPointerTable::update_pointers();
4529 #endif
4530 g1_policy()->print_age_table();
4531 }
4532
4533 void G1CollectedHeap::record_obj_copy_mem_stats() {
4534 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4535
4536 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4537 create_g1_evac_summary(&_old_evac_stats));
4538 }
4539
4540 void G1CollectedHeap::free_region(HeapRegion* hr,
4541 FreeRegionList* free_list,
4542 bool skip_remset,
4543 bool skip_hot_card_cache,
4544 bool locked) {
4545 assert(!hr->is_free(), "the region should not be free");
4546 assert(!hr->is_empty(), "the region should not be empty");
4547 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4548 assert(free_list != NULL, "pre-condition");
4549
4550 if (G1VerifyBitmaps) {
4551 MemRegion mr(hr->bottom(), hr->end());
4552 concurrent_mark()->clearRangePrevBitmap(mr);
4553 }
4554
4555 // Clear the card counts for this region.
4556 // Note: we only need to do this if the region is not young
4557 // (since we don't refine cards in young regions).
4558 if (!skip_hot_card_cache && !hr->is_young()) {
4559 _hot_card_cache->reset_card_counts(hr);
4560 }
4561 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4562 free_list->add_ordered(hr);
4563 }
4564
4565 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4566 FreeRegionList* free_list,
4567 bool skip_remset) {
4568 assert(hr->is_humongous(), "this is only for humongous regions");
4569 assert(free_list != NULL, "pre-condition");
4570 hr->clear_humongous();
4571 free_region(hr, free_list, skip_remset);
4572 }
4573
4574 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4575 const uint humongous_regions_removed) {
4576 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4577 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4578 _old_set.bulk_remove(old_regions_removed);
4579 _humongous_set.bulk_remove(humongous_regions_removed);
4580 }
4581
4582 }
4583
4584 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4585 assert(list != NULL, "list can't be null");
4586 if (!list->is_empty()) {
4587 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4588 _hrm.insert_list_into_free_list(list);
4589 }
4590 }
4591
4592 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4593 decrease_used(bytes);
4594 }
4595
4596 class G1ParScrubRemSetTask: public AbstractGangTask {
4597 protected:
4598 G1RemSet* _g1rs;
4599 HeapRegionClaimer _hrclaimer;
4600
4601 public:
4602 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4603 AbstractGangTask("G1 ScrubRS"),
4604 _g1rs(g1_rs),
4605 _hrclaimer(num_workers) {
4606 }
4607
4608 void work(uint worker_id) {
4609 _g1rs->scrub(worker_id, &_hrclaimer);
4610 }
4611 };
4612
4613 void G1CollectedHeap::scrub_rem_set() {
4614 uint num_workers = workers()->active_workers();
4615 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4616 workers()->run_task(&g1_par_scrub_rs_task);
4617 }
4618
4619 class G1FreeCollectionSetTask : public AbstractGangTask {
4620 private:
4621
4622 // Closure applied to all regions in the collection set to do work that needs to
4623 // be done serially in a single thread.
4624 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4625 private:
4626 EvacuationInfo* _evacuation_info;
4627 const size_t* _surviving_young_words;
4628
4629 // Bytes used in successfully evacuated regions before the evacuation.
4630 size_t _before_used_bytes;
4631 // Bytes used in unsucessfully evacuated regions before the evacuation
4632 size_t _after_used_bytes;
4633
4634 size_t _bytes_allocated_in_old_since_last_gc;
4635
4636 size_t _failure_used_words;
4637 size_t _failure_waste_words;
4638
4639 FreeRegionList _local_free_list;
4640 public:
4641 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4642 HeapRegionClosure(),
4643 _evacuation_info(evacuation_info),
4644 _surviving_young_words(surviving_young_words),
4645 _before_used_bytes(0),
4646 _after_used_bytes(0),
4647 _bytes_allocated_in_old_since_last_gc(0),
4648 _failure_used_words(0),
4649 _failure_waste_words(0),
4650 _local_free_list("Local Region List for CSet Freeing") {
4651 }
4652
4653 virtual bool doHeapRegion(HeapRegion* r) {
4654 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4655
4656 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4657 g1h->clear_in_cset(r);
4658
4659 if (r->is_young()) {
4660 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4661 "Young index %d is wrong for region %u of type %s with %u young regions",
4662 r->young_index_in_cset(),
4663 r->hrm_index(),
4664 r->get_type_str(),
4665 g1h->collection_set()->young_region_length());
4666 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4667 r->record_surv_words_in_group(words_survived);
4668 }
4669
4670 if (!r->evacuation_failed()) {
4671 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4672 _before_used_bytes += r->used();
4673 g1h->free_region(r,
4674 &_local_free_list,
4675 true, /* skip_remset */
4676 true, /* skip_hot_card_cache */
4677 true /* locked */);
4678 } else {
4679 r->uninstall_surv_rate_group();
4680 r->set_young_index_in_cset(-1);
4681 r->set_evacuation_failed(false);
4682 // When moving a young gen region to old gen, we "allocate" that whole region
4683 // there. This is in addition to any already evacuated objects. Notify the
4684 // policy about that.
4685 // Old gen regions do not cause an additional allocation: both the objects
4686 // still in the region and the ones already moved are accounted for elsewhere.
4687 if (r->is_young()) {
4688 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4689 }
4690 // The region is now considered to be old.
4691 r->set_old();
4692 // Do some allocation statistics accounting. Regions that failed evacuation
4693 // are always made old, so there is no need to update anything in the young
4694 // gen statistics, but we need to update old gen statistics.
4695 size_t used_words = r->marked_bytes() / HeapWordSize;
4696
4697 _failure_used_words += used_words;
4698 _failure_waste_words += HeapRegion::GrainWords - used_words;
4699
4700 g1h->old_set_add(r);
4701 _after_used_bytes += r->used();
4702 }
4703 return false;
4704 }
4705
4706 void complete_work() {
4707 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4708
4709 _evacuation_info->set_regions_freed(_local_free_list.length());
4710 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4711
4712 g1h->prepend_to_freelist(&_local_free_list);
4713 g1h->decrement_summary_bytes(_before_used_bytes);
4714
4715 G1Policy* policy = g1h->g1_policy();
4716 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4717
4718 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4719 }
4720 };
4721
4722 G1CollectionSet* _collection_set;
4723 G1SerialFreeCollectionSetClosure _cl;
4724 const size_t* _surviving_young_words;
4725
4726 size_t _rs_lengths;
4727
4728 volatile jint _serial_work_claim;
4729
4730 struct WorkItem {
4731 uint region_idx;
4732 bool is_young;
4733 bool evacuation_failed;
4734
4735 WorkItem(HeapRegion* r) {
4736 region_idx = r->hrm_index();
4737 is_young = r->is_young();
4738 evacuation_failed = r->evacuation_failed();
4739 }
4740 };
4741
4742 volatile size_t _parallel_work_claim;
4743 size_t _num_work_items;
4744 WorkItem* _work_items;
4745
4746 void do_serial_work() {
4747 // Need to grab the lock to be allowed to modify the old region list.
4748 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4749 _collection_set->iterate(&_cl);
4750 }
4751
4752 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4753 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4754
4755 HeapRegion* r = g1h->region_at(region_idx);
4756 assert(!g1h->is_on_master_free_list(r), "sanity");
4757
4758 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4759
4760 if (!is_young) {
4761 g1h->_hot_card_cache->reset_card_counts(r);
4762 }
4763
4764 if (!evacuation_failed) {
4765 r->rem_set()->clear_locked();
4766 }
4767 }
4768
4769 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4770 private:
4771 size_t _cur_idx;
4772 WorkItem* _work_items;
4773 public:
4774 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4775
4776 virtual bool doHeapRegion(HeapRegion* r) {
4777 _work_items[_cur_idx++] = WorkItem(r);
4778 return false;
4779 }
4780 };
4781
4782 void prepare_work() {
4783 G1PrepareFreeCollectionSetClosure cl(_work_items);
4784 _collection_set->iterate(&cl);
4785 }
4786
4787 void complete_work() {
4788 _cl.complete_work();
4789
4790 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4791 policy->record_max_rs_lengths(_rs_lengths);
4792 policy->cset_regions_freed();
4793 }
4794 public:
4795 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4796 AbstractGangTask("G1 Free Collection Set"),
4797 _cl(evacuation_info, surviving_young_words),
4798 _collection_set(collection_set),
4799 _surviving_young_words(surviving_young_words),
4800 _serial_work_claim(0),
4801 _rs_lengths(0),
4802 _parallel_work_claim(0),
4803 _num_work_items(collection_set->region_length()),
4804 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4805 prepare_work();
4806 }
4807
4808 ~G1FreeCollectionSetTask() {
4809 complete_work();
4810 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4811 }
4812
4813 // Chunk size for work distribution. The chosen value has been determined experimentally
4814 // to be a good tradeoff between overhead and achievable parallelism.
4815 static uint chunk_size() { return 32; }
4816
4817 virtual void work(uint worker_id) {
4818 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4819
4820 // Claim serial work.
4821 if (_serial_work_claim == 0) {
4822 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4823 if (value == 0) {
4824 double serial_time = os::elapsedTime();
4825 do_serial_work();
4826 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4827 }
4828 }
4829
4830 // Start parallel work.
4831 double young_time = 0.0;
4832 bool has_young_time = false;
4833 double non_young_time = 0.0;
4834 bool has_non_young_time = false;
4835
4836 while (true) {
4837 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4838 size_t cur = end - chunk_size();
4839
4840 if (cur >= _num_work_items) {
4841 break;
4842 }
4843
4844 double start_time = os::elapsedTime();
4845
4846 end = MIN2(end, _num_work_items);
4847
4848 for (; cur < end; cur++) {
4849 bool is_young = _work_items[cur].is_young;
4850
4851 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4852
4853 double end_time = os::elapsedTime();
4854 double time_taken = end_time - start_time;
4855 if (is_young) {
4856 young_time += time_taken;
4857 has_young_time = true;
4858 } else {
4859 non_young_time += time_taken;
4860 has_non_young_time = true;
4861 }
4862 start_time = end_time;
4863 }
4864 }
4865
4866 if (has_young_time) {
4867 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4868 }
4869 if (has_non_young_time) {
4870 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4871 }
4872 }
4873 };
4874
4875 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4876 _eden.clear();
4877
4878 double free_cset_start_time = os::elapsedTime();
4879
4880 {
4881 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4882 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4883
4884 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4885
4886 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4887 cl.name(),
4888 num_workers,
4889 _collection_set.region_length());
4890 workers()->run_task(&cl, num_workers);
4891 }
4892 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4893
4894 collection_set->clear();
4895 }
4896
4897 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4898 private:
4899 FreeRegionList* _free_region_list;
4900 HeapRegionSet* _proxy_set;
4901 uint _humongous_regions_removed;
4902 size_t _freed_bytes;
4903 public:
4904
4905 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4906 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4907 }
4908
4909 virtual bool doHeapRegion(HeapRegion* r) {
4910 if (!r->is_starts_humongous()) {
4911 return false;
4912 }
4913
4914 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4915
4916 oop obj = (oop)r->bottom();
4917 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4918
4919 // The following checks whether the humongous object is live are sufficient.
4920 // The main additional check (in addition to having a reference from the roots
4921 // or the young gen) is whether the humongous object has a remembered set entry.
4922 //
4923 // A humongous object cannot be live if there is no remembered set for it
4924 // because:
4925 // - there can be no references from within humongous starts regions referencing
4926 // the object because we never allocate other objects into them.
4927 // (I.e. there are no intra-region references that may be missed by the
4928 // remembered set)
4929 // - as soon there is a remembered set entry to the humongous starts region
4930 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4931 // until the end of a concurrent mark.
4932 //
4933 // It is not required to check whether the object has been found dead by marking
4934 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4935 // all objects allocated during that time are considered live.
4936 // SATB marking is even more conservative than the remembered set.
4937 // So if at this point in the collection there is no remembered set entry,
4938 // nobody has a reference to it.
4939 // At the start of collection we flush all refinement logs, and remembered sets
4940 // are completely up-to-date wrt to references to the humongous object.
4941 //
4942 // Other implementation considerations:
4943 // - never consider object arrays at this time because they would pose
4944 // considerable effort for cleaning up the the remembered sets. This is
4945 // required because stale remembered sets might reference locations that
4946 // are currently allocated into.
4947 uint region_idx = r->hrm_index();
4948 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4949 !r->rem_set()->is_empty()) {
4950 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",
4951 region_idx,
4952 (size_t)obj->size() * HeapWordSize,
4953 p2i(r->bottom()),
4954 r->rem_set()->occupied(),
4955 r->rem_set()->strong_code_roots_list_length(),
4956 next_bitmap->isMarked(r->bottom()),
4957 g1h->is_humongous_reclaim_candidate(region_idx),
4958 obj->is_typeArray()
4959 );
4960 return false;
4961 }
4962
4963 guarantee(obj->is_typeArray(),
4964 "Only eagerly reclaiming type arrays is supported, but the object "
4965 PTR_FORMAT " is not.", p2i(r->bottom()));
4966
4967 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",
4968 region_idx,
4969 (size_t)obj->size() * HeapWordSize,
4970 p2i(r->bottom()),
4971 r->rem_set()->occupied(),
4972 r->rem_set()->strong_code_roots_list_length(),
4973 next_bitmap->isMarked(r->bottom()),
4974 g1h->is_humongous_reclaim_candidate(region_idx),
4975 obj->is_typeArray()
4976 );
4977
4978 // Need to clear mark bit of the humongous object if already set.
4979 if (next_bitmap->isMarked(r->bottom())) {
4980 next_bitmap->clear(r->bottom());
4981 }
4982 do {
4983 HeapRegion* next = g1h->next_region_in_humongous(r);
4984 _freed_bytes += r->used();
4985 r->set_containing_set(NULL);
4986 _humongous_regions_removed++;
4987 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4988 r = next;
4989 } while (r != NULL);
4990
4991 return false;
4992 }
4993
4994 uint humongous_free_count() {
4995 return _humongous_regions_removed;
4996 }
4997
4998 size_t bytes_freed() const {
4999 return _freed_bytes;
5000 }
5001 };
5002
5003 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5004 assert_at_safepoint(true);
5005
5006 if (!G1EagerReclaimHumongousObjects ||
5007 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5008 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5009 return;
5010 }
5011
5012 double start_time = os::elapsedTime();
5013
5014 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5015
5016 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5017 heap_region_iterate(&cl);
5018
5019 remove_from_old_sets(0, cl.humongous_free_count());
5020
5021 G1HRPrinter* hrp = hr_printer();
5022 if (hrp->is_active()) {
5023 FreeRegionListIterator iter(&local_cleanup_list);
5024 while (iter.more_available()) {
5025 HeapRegion* hr = iter.get_next();
5026 hrp->cleanup(hr);
5027 }
5028 }
5029
5030 prepend_to_freelist(&local_cleanup_list);
5031 decrement_summary_bytes(cl.bytes_freed());
5032
5033 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5034 cl.humongous_free_count());
5035 }
5036
5037 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5038 public:
5039 virtual bool doHeapRegion(HeapRegion* r) {
5040 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5041 G1CollectedHeap::heap()->clear_in_cset(r);
5042 r->set_young_index_in_cset(-1);
5043 return false;
5044 }
5045 };
5046
5047 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5048 G1AbandonCollectionSetClosure cl;
5049 collection_set->iterate(&cl);
5050
5051 collection_set->clear();
5052 collection_set->stop_incremental_building();
5053 }
5054
5055 void G1CollectedHeap::set_free_regions_coming() {
5056 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5057
5058 assert(!free_regions_coming(), "pre-condition");
5059 _free_regions_coming = true;
5060 }
5061
5062 void G1CollectedHeap::reset_free_regions_coming() {
5063 assert(free_regions_coming(), "pre-condition");
5064
5065 {
5066 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5067 _free_regions_coming = false;
5068 SecondaryFreeList_lock->notify_all();
5069 }
5070
5071 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5072 }
5073
5074 void G1CollectedHeap::wait_while_free_regions_coming() {
5075 // Most of the time we won't have to wait, so let's do a quick test
5076 // first before we take the lock.
5077 if (!free_regions_coming()) {
5078 return;
5079 }
5080
5081 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5082
5083 {
5084 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5085 while (free_regions_coming()) {
5086 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5087 }
5088 }
5089
5090 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5091 }
5092
5093 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5094 return _allocator->is_retained_old_region(hr);
5095 }
5096
5097 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5098 _eden.add(hr);
5099 _g1_policy->set_region_eden(hr);
5100 }
5101
5102 #ifdef ASSERT
5103
5104 class NoYoungRegionsClosure: public HeapRegionClosure {
5105 private:
5106 bool _success;
5107 public:
5108 NoYoungRegionsClosure() : _success(true) { }
5109 bool doHeapRegion(HeapRegion* r) {
5110 if (r->is_young()) {
5111 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5112 p2i(r->bottom()), p2i(r->end()));
5113 _success = false;
5114 }
5115 return false;
5116 }
5117 bool success() { return _success; }
5118 };
5119
5120 bool G1CollectedHeap::check_young_list_empty() {
5121 bool ret = (young_regions_count() == 0);
5122
5123 NoYoungRegionsClosure closure;
5124 heap_region_iterate(&closure);
5125 ret = ret && closure.success();
5126
5127 return ret;
5128 }
5129
5130 #endif // ASSERT
5131
5132 class TearDownRegionSetsClosure : public HeapRegionClosure {
5133 private:
5134 HeapRegionSet *_old_set;
5135
5136 public:
5137 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5138
5139 bool doHeapRegion(HeapRegion* r) {
5140 if (r->is_old()) {
5141 _old_set->remove(r);
5142 } else if(r->is_young()) {
5143 r->uninstall_surv_rate_group();
5144 } else {
5145 // We ignore free regions, we'll empty the free list afterwards.
5146 // We ignore humongous regions, we're not tearing down the
5147 // humongous regions set.
5148 assert(r->is_free() || r->is_humongous(),
5149 "it cannot be another type");
5150 }
5151 return false;
5152 }
5153
5154 ~TearDownRegionSetsClosure() {
5155 assert(_old_set->is_empty(), "post-condition");
5156 }
5157 };
5158
5159 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5160 assert_at_safepoint(true /* should_be_vm_thread */);
5161
5162 if (!free_list_only) {
5163 TearDownRegionSetsClosure cl(&_old_set);
5164 heap_region_iterate(&cl);
5165
5166 // Note that emptying the _young_list is postponed and instead done as
5167 // the first step when rebuilding the regions sets again. The reason for
5168 // this is that during a full GC string deduplication needs to know if
5169 // a collected region was young or old when the full GC was initiated.
5170 }
5171 _hrm.remove_all_free_regions();
5172 }
5173
5174 void G1CollectedHeap::increase_used(size_t bytes) {
5175 _summary_bytes_used += bytes;
5176 }
5177
5178 void G1CollectedHeap::decrease_used(size_t bytes) {
5179 assert(_summary_bytes_used >= bytes,
5180 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5181 _summary_bytes_used, bytes);
5182 _summary_bytes_used -= bytes;
5183 }
5184
5185 void G1CollectedHeap::set_used(size_t bytes) {
5186 _summary_bytes_used = bytes;
5187 }
5188
5189 class RebuildRegionSetsClosure : public HeapRegionClosure {
5190 private:
5191 bool _free_list_only;
5192 HeapRegionSet* _old_set;
5193 HeapRegionManager* _hrm;
5194 size_t _total_used;
5195
5196 public:
5197 RebuildRegionSetsClosure(bool free_list_only,
5198 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5199 _free_list_only(free_list_only),
5200 _old_set(old_set), _hrm(hrm), _total_used(0) {
5201 assert(_hrm->num_free_regions() == 0, "pre-condition");
5202 if (!free_list_only) {
5203 assert(_old_set->is_empty(), "pre-condition");
5204 }
5205 }
5206
5207 bool doHeapRegion(HeapRegion* r) {
5208 if (r->is_empty()) {
5209 // Add free regions to the free list
5210 r->set_free();
5211 r->set_allocation_context(AllocationContext::system());
5212 _hrm->insert_into_free_list(r);
5213 } else if (!_free_list_only) {
5214
5215 if (r->is_humongous()) {
5216 // We ignore humongous regions. We left the humongous set unchanged.
5217 } else {
5218 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5219 // We now consider all regions old, so register as such. Leave
5220 // archive regions set that way, however, while still adding
5221 // them to the old set.
5222 if (!r->is_archive()) {
5223 r->set_old();
5224 }
5225 _old_set->add(r);
5226 }
5227 _total_used += r->used();
5228 }
5229
5230 return false;
5231 }
5232
5233 size_t total_used() {
5234 return _total_used;
5235 }
5236 };
5237
5238 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5239 assert_at_safepoint(true /* should_be_vm_thread */);
5240
5241 if (!free_list_only) {
5242 _eden.clear();
5243 _survivor.clear();
5244 }
5245
5246 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5247 heap_region_iterate(&cl);
5248
5249 if (!free_list_only) {
5250 set_used(cl.total_used());
5251 if (_archive_allocator != NULL) {
5252 _archive_allocator->clear_used();
5253 }
5254 }
5255 assert(used_unlocked() == recalculate_used(),
5256 "inconsistent used_unlocked(), "
5257 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5258 used_unlocked(), recalculate_used());
5259 }
5260
5261 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5262 _refine_cte_cl->set_concurrent(concurrent);
5263 }
5264
5265 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5266 HeapRegion* hr = heap_region_containing(p);
5267 return hr->is_in(p);
5268 }
5269
5270 // Methods for the mutator alloc region
5271
5272 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5273 bool force) {
5274 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5275 assert(!force || g1_policy()->can_expand_young_list(),
5276 "if force is true we should be able to expand the young list");
5277 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5278 if (force || should_allocate) {
5279 HeapRegion* new_alloc_region = new_region(word_size,
5280 false /* is_old */,
5281 false /* do_expand */);
5282 if (new_alloc_region != NULL) {
5283 set_region_short_lived_locked(new_alloc_region);
5284 _hr_printer.alloc(new_alloc_region, !should_allocate);
5285 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5286 return new_alloc_region;
5287 }
5288 }
5289 return NULL;
5290 }
5291
5292 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5293 size_t allocated_bytes) {
5294 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5295 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5296
5297 collection_set()->add_eden_region(alloc_region);
5298 increase_used(allocated_bytes);
5299 _hr_printer.retire(alloc_region);
5300 // We update the eden sizes here, when the region is retired,
5301 // instead of when it's allocated, since this is the point that its
5302 // used space has been recored in _summary_bytes_used.
5303 g1mm()->update_eden_size();
5304 }
5305
5306 // Methods for the GC alloc regions
5307
5308 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5309 if (dest.is_old()) {
5310 return true;
5311 } else {
5312 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5313 }
5314 }
5315
5316 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5317 assert(FreeList_lock->owned_by_self(), "pre-condition");
5318
5319 if (!has_more_regions(dest)) {
5320 return NULL;
5321 }
5322
5323 const bool is_survivor = dest.is_young();
5324
5325 HeapRegion* new_alloc_region = new_region(word_size,
5326 !is_survivor,
5327 true /* do_expand */);
5328 if (new_alloc_region != NULL) {
5329 // We really only need to do this for old regions given that we
5330 // should never scan survivors. But it doesn't hurt to do it
5331 // for survivors too.
5332 new_alloc_region->record_timestamp();
5333 if (is_survivor) {
5334 new_alloc_region->set_survivor();
5335 _survivor.add(new_alloc_region);
5336 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5337 } else {
5338 new_alloc_region->set_old();
5339 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5340 }
5341 _hr_printer.alloc(new_alloc_region);
5342 bool during_im = collector_state()->during_initial_mark_pause();
5343 new_alloc_region->note_start_of_copying(during_im);
5344 return new_alloc_region;
5345 }
5346 return NULL;
5347 }
5348
5349 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5350 size_t allocated_bytes,
5351 InCSetState dest) {
5352 bool during_im = collector_state()->during_initial_mark_pause();
5353 alloc_region->note_end_of_copying(during_im);
5354 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5355 if (dest.is_old()) {
5356 _old_set.add(alloc_region);
5357 }
5358 _hr_printer.retire(alloc_region);
5359 }
5360
5361 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5362 bool expanded = false;
5363 uint index = _hrm.find_highest_free(&expanded);
5364
5365 if (index != G1_NO_HRM_INDEX) {
5366 if (expanded) {
5367 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5368 HeapRegion::GrainWords * HeapWordSize);
5369 }
5370 _hrm.allocate_free_regions_starting_at(index, 1);
5371 return region_at(index);
5372 }
5373 return NULL;
5374 }
5375
5376 // Optimized nmethod scanning
5377
5378 class RegisterNMethodOopClosure: public OopClosure {
5379 G1CollectedHeap* _g1h;
5380 nmethod* _nm;
5381
5382 template <class T> void do_oop_work(T* p) {
5383 T heap_oop = oopDesc::load_heap_oop(p);
5384 if (!oopDesc::is_null(heap_oop)) {
5385 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5386 HeapRegion* hr = _g1h->heap_region_containing(obj);
5387 assert(!hr->is_continues_humongous(),
5388 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5389 " starting at " HR_FORMAT,
5390 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5391
5392 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5393 hr->add_strong_code_root_locked(_nm);
5394 }
5395 }
5396
5397 public:
5398 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5399 _g1h(g1h), _nm(nm) {}
5400
5401 void do_oop(oop* p) { do_oop_work(p); }
5402 void do_oop(narrowOop* p) { do_oop_work(p); }
5403 };
5404
5405 class UnregisterNMethodOopClosure: public OopClosure {
5406 G1CollectedHeap* _g1h;
5407 nmethod* _nm;
5408
5409 template <class T> void do_oop_work(T* p) {
5410 T heap_oop = oopDesc::load_heap_oop(p);
5411 if (!oopDesc::is_null(heap_oop)) {
5412 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5413 HeapRegion* hr = _g1h->heap_region_containing(obj);
5414 assert(!hr->is_continues_humongous(),
5415 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5416 " starting at " HR_FORMAT,
5417 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5418
5419 hr->remove_strong_code_root(_nm);
5420 }
5421 }
5422
5423 public:
5424 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5425 _g1h(g1h), _nm(nm) {}
5426
5427 void do_oop(oop* p) { do_oop_work(p); }
5428 void do_oop(narrowOop* p) { do_oop_work(p); }
5429 };
5430
5431 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5432 CollectedHeap::register_nmethod(nm);
5433
5434 guarantee(nm != NULL, "sanity");
5435 RegisterNMethodOopClosure reg_cl(this, nm);
5436 nm->oops_do(®_cl);
5437 }
5438
5439 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5440 CollectedHeap::unregister_nmethod(nm);
5441
5442 guarantee(nm != NULL, "sanity");
5443 UnregisterNMethodOopClosure reg_cl(this, nm);
5444 nm->oops_do(®_cl, true);
5445 }
5446
5447 void G1CollectedHeap::purge_code_root_memory() {
5448 double purge_start = os::elapsedTime();
5449 G1CodeRootSet::purge();
5450 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5451 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5452 }
5453
5454 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5455 G1CollectedHeap* _g1h;
5456
5457 public:
5458 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5459 _g1h(g1h) {}
5460
5461 void do_code_blob(CodeBlob* cb) {
5462 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5463 if (nm == NULL) {
5464 return;
5465 }
5466
5467 if (ScavengeRootsInCode) {
5468 _g1h->register_nmethod(nm);
5469 }
5470 }
5471 };
5472
5473 void G1CollectedHeap::rebuild_strong_code_roots() {
5474 RebuildStrongCodeRootClosure blob_cl(this);
5475 CodeCache::blobs_do(&blob_cl);
5476 }