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