1 /*
2 * Copyright (c) 2001, 2015, 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 "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1Allocator.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1Log.hpp"
43 #include "gc/g1/g1MarkSweep.hpp"
44 #include "gc/g1/g1OopClosures.inline.hpp"
45 #include "gc/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc/g1/g1RemSet.inline.hpp"
48 #include "gc/g1/g1RootClosures.hpp"
49 #include "gc/g1/g1RootProcessor.hpp"
50 #include "gc/g1/g1StringDedup.hpp"
51 #include "gc/g1/g1YCTypes.hpp"
52 #include "gc/g1/heapRegion.inline.hpp"
53 #include "gc/g1/heapRegionRemSet.hpp"
54 #include "gc/g1/heapRegionSet.inline.hpp"
55 #include "gc/g1/suspendibleThreadSet.hpp"
56 #include "gc/g1/vm_operations_g1.hpp"
57 #include "gc/shared/gcHeapSummary.hpp"
58 #include "gc/shared/gcId.hpp"
59 #include "gc/shared/gcLocker.inline.hpp"
60 #include "gc/shared/gcTimer.hpp"
61 #include "gc/shared/gcTrace.hpp"
62 #include "gc/shared/gcTraceTime.hpp"
63 #include "gc/shared/generationSpec.hpp"
64 #include "gc/shared/isGCActiveMark.hpp"
65 #include "gc/shared/referenceProcessor.hpp"
66 #include "gc/shared/taskqueue.inline.hpp"
67 #include "memory/allocation.hpp"
68 #include "memory/iterator.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/init.hpp"
72 #include "runtime/orderAccess.inline.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "utilities/globalDefinitions.hpp"
75 #include "utilities/stack.inline.hpp"
76
77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_processed;
117
118 public:
119 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 *card_ptr = CardTableModRefBS::dirty_card_val();
123 _num_processed++;
124 return true;
125 }
126
127 size_t num_processed() const { return _num_processed; }
128 };
129
130
131 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
132 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
133 }
134
135 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
136 // The from card cache is not the memory that is actually committed. So we cannot
137 // take advantage of the zero_filled parameter.
138 reset_from_card_cache(start_idx, num_regions);
139 }
140
141 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
142 {
143 // Claim the right to put the region on the dirty cards region list
144 // by installing a self pointer.
145 HeapRegion* next = hr->get_next_dirty_cards_region();
146 if (next == NULL) {
147 HeapRegion* res = (HeapRegion*)
148 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
149 NULL);
150 if (res == NULL) {
151 HeapRegion* head;
152 do {
153 // Put the region to the dirty cards region list.
154 head = _dirty_cards_region_list;
155 next = (HeapRegion*)
156 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
157 if (next == head) {
158 assert(hr->get_next_dirty_cards_region() == hr,
159 "hr->get_next_dirty_cards_region() != hr");
160 if (next == NULL) {
161 // The last region in the list points to itself.
162 hr->set_next_dirty_cards_region(hr);
163 } else {
164 hr->set_next_dirty_cards_region(next);
165 }
166 }
167 } while (next != head);
168 }
169 }
170 }
171
172 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
173 {
174 HeapRegion* head;
175 HeapRegion* hr;
176 do {
177 head = _dirty_cards_region_list;
178 if (head == NULL) {
179 return NULL;
180 }
181 HeapRegion* new_head = head->get_next_dirty_cards_region();
182 if (head == new_head) {
183 // The last region.
184 new_head = NULL;
185 }
186 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
187 head);
188 } while (hr != head);
189 assert(hr != NULL, "invariant");
190 hr->set_next_dirty_cards_region(NULL);
191 return hr;
192 }
193
194 // Returns true if the reference points to an object that
195 // can move in an incremental collection.
196 bool G1CollectedHeap::is_scavengable(const void* p) {
197 HeapRegion* hr = heap_region_containing(p);
198 return !hr->is_pinned();
199 }
200
201 // Private methods.
202
203 HeapRegion*
204 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
205 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
206 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
207 if (!_secondary_free_list.is_empty()) {
208 if (G1ConcRegionFreeingVerbose) {
209 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
210 "secondary_free_list has %u entries",
211 _secondary_free_list.length());
212 }
213 // It looks as if there are free regions available on the
214 // secondary_free_list. Let's move them to the free_list and try
215 // again to allocate from it.
216 append_secondary_free_list();
217
218 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
219 "empty we should have moved at least one entry to the free_list");
220 HeapRegion* res = _hrm.allocate_free_region(is_old);
221 if (G1ConcRegionFreeingVerbose) {
222 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
223 "allocated " HR_FORMAT " from secondary_free_list",
224 HR_FORMAT_PARAMS(res));
225 }
226 return res;
227 }
228
229 // Wait here until we get notified either when (a) there are no
230 // more free regions coming or (b) some regions have been moved on
231 // the secondary_free_list.
232 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
233 }
234
235 if (G1ConcRegionFreeingVerbose) {
236 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
237 "could not allocate from secondary_free_list");
238 }
239 return NULL;
240 }
241
242 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
243 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
244 "the only time we use this to allocate a humongous region is "
245 "when we are allocating a single humongous region");
246
247 HeapRegion* res;
248 if (G1StressConcRegionFreeing) {
249 if (!_secondary_free_list.is_empty()) {
250 if (G1ConcRegionFreeingVerbose) {
251 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
252 "forced to look at the secondary_free_list");
253 }
254 res = new_region_try_secondary_free_list(is_old);
255 if (res != NULL) {
256 return res;
257 }
258 }
259 }
260
261 res = _hrm.allocate_free_region(is_old);
262
263 if (res == NULL) {
264 if (G1ConcRegionFreeingVerbose) {
265 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
266 "res == NULL, trying the secondary_free_list");
267 }
268 res = new_region_try_secondary_free_list(is_old);
269 }
270 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
271 // Currently, only attempts to allocate GC alloc regions set
272 // do_expand to true. So, we should only reach here during a
273 // safepoint. If this assumption changes we might have to
274 // reconsider the use of _expand_heap_after_alloc_failure.
275 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
276
277 ergo_verbose1(ErgoHeapSizing,
278 "attempt heap expansion",
279 ergo_format_reason("region allocation request failed")
280 ergo_format_byte("allocation request"),
281 word_size * HeapWordSize);
282 if (expand(word_size * HeapWordSize)) {
283 // Given that expand() succeeded in expanding the heap, and we
284 // always expand the heap by an amount aligned to the heap
285 // region size, the free list should in theory not be empty.
286 // In either case allocate_free_region() will check for NULL.
287 res = _hrm.allocate_free_region(is_old);
288 } else {
289 _expand_heap_after_alloc_failure = false;
290 }
291 }
292 return res;
293 }
294
295 HeapWord*
296 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
297 uint num_regions,
298 size_t word_size,
299 AllocationContext_t context) {
300 assert(first != G1_NO_HRM_INDEX, "pre-condition");
301 assert(is_humongous(word_size), "word_size should be humongous");
302 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
303
304 // Index of last region in the series + 1.
305 uint last = first + num_regions;
306
307 // We need to initialize the region(s) we just discovered. This is
308 // a bit tricky given that it can happen concurrently with
309 // refinement threads refining cards on these regions and
310 // potentially wanting to refine the BOT as they are scanning
311 // those cards (this can happen shortly after a cleanup; see CR
312 // 6991377). So we have to set up the region(s) carefully and in
313 // a specific order.
314
315 // The word size sum of all the regions we will allocate.
316 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
317 assert(word_size <= word_size_sum, "sanity");
318
319 // This will be the "starts humongous" region.
320 HeapRegion* first_hr = region_at(first);
321 // The header of the new object will be placed at the bottom of
322 // the first region.
323 HeapWord* new_obj = first_hr->bottom();
324 // This will be the new top of the new object.
325 HeapWord* obj_top = new_obj + word_size;
326
327 // First, we need to zero the header of the space that we will be
328 // allocating. When we update top further down, some refinement
329 // threads might try to scan the region. By zeroing the header we
330 // ensure that any thread that will try to scan the region will
331 // come across the zero klass word and bail out.
332 //
333 // NOTE: It would not have been correct to have used
334 // CollectedHeap::fill_with_object() and make the space look like
335 // an int array. The thread that is doing the allocation will
336 // later update the object header to a potentially different array
337 // type and, for a very short period of time, the klass and length
338 // fields will be inconsistent. This could cause a refinement
339 // thread to calculate the object size incorrectly.
340 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
341
342 // We will set up the first region as "starts humongous". This
343 // will also update the BOT covering all the regions to reflect
344 // that there is a single object that starts at the bottom of the
345 // first region.
346 first_hr->set_starts_humongous(obj_top);
347 first_hr->set_allocation_context(context);
348 // Then, if there are any, we will set up the "continues
349 // humongous" regions.
350 HeapRegion* hr = NULL;
351 for (uint i = first + 1; i < last; ++i) {
352 hr = region_at(i);
353 hr->set_continues_humongous(first_hr);
354 hr->set_allocation_context(context);
355 }
356
357 // Up to this point no concurrent thread would have been able to
358 // do any scanning on any region in this series. All the top
359 // fields still point to bottom, so the intersection between
360 // [bottom,top] and [card_start,card_end] will be empty. Before we
361 // update the top fields, we'll do a storestore to make sure that
362 // no thread sees the update to top before the zeroing of the
363 // object header and the BOT initialization.
364 OrderAccess::storestore();
365
366 // Now that the BOT and the object header have been initialized,
367 // we can update top of the "starts humongous" region.
368 first_hr->set_top(MIN2(first_hr->end(), obj_top));
369 if (_hr_printer.is_active()) {
370 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
371 }
372
373 // Now, we will update the top fields of the "continues humongous"
374 // regions.
375 hr = NULL;
376 for (uint i = first + 1; i < last; ++i) {
377 hr = region_at(i);
378 if ((i + 1) == last) {
379 // last continues humongous region
380 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
381 "new_top should fall on this region");
382 hr->set_top(obj_top);
383 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
384 } else {
385 // not last one
386 assert(obj_top > hr->end(), "obj_top should be above this region");
387 hr->set_top(hr->end());
388 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
389 }
390 }
391 // If we have continues humongous regions (hr != NULL), its top should
392 // match obj_top.
393 assert(hr == NULL || (hr->top() == obj_top), "sanity");
394 check_bitmaps("Humongous Region Allocation", first_hr);
395
396 increase_used(word_size * HeapWordSize);
397
398 for (uint i = first; i < last; ++i) {
399 _humongous_set.add(region_at(i));
400 }
401
402 return new_obj;
403 }
404
405 // If could fit into free regions w/o expansion, try.
406 // Otherwise, if can expand, do so.
407 // Otherwise, if using ex regions might help, try with ex given back.
408 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
409 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
410
411 verify_region_sets_optional();
412
413 uint first = G1_NO_HRM_INDEX;
414 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
415
416 if (obj_regions == 1) {
417 // Only one region to allocate, try to use a fast path by directly allocating
418 // from the free lists. Do not try to expand here, we will potentially do that
419 // later.
420 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
421 if (hr != NULL) {
422 first = hr->hrm_index();
423 }
424 } else {
425 // We can't allocate humongous regions spanning more than one region while
426 // cleanupComplete() is running, since some of the regions we find to be
427 // empty might not yet be added to the free list. It is not straightforward
428 // to know in which list they are on so that we can remove them. We only
429 // need to do this if we need to allocate more than one region to satisfy the
430 // current humongous allocation request. If we are only allocating one region
431 // we use the one-region region allocation code (see above), that already
432 // potentially waits for regions from the secondary free list.
433 wait_while_free_regions_coming();
434 append_secondary_free_list_if_not_empty_with_lock();
435
436 // Policy: Try only empty regions (i.e. already committed first). Maybe we
437 // are lucky enough to find some.
438 first = _hrm.find_contiguous_only_empty(obj_regions);
439 if (first != G1_NO_HRM_INDEX) {
440 _hrm.allocate_free_regions_starting_at(first, obj_regions);
441 }
442 }
443
444 if (first == G1_NO_HRM_INDEX) {
445 // Policy: We could not find enough regions for the humongous object in the
446 // free list. Look through the heap to find a mix of free and uncommitted regions.
447 // If so, try expansion.
448 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
449 if (first != G1_NO_HRM_INDEX) {
450 // We found something. Make sure these regions are committed, i.e. expand
451 // the heap. Alternatively we could do a defragmentation GC.
452 ergo_verbose1(ErgoHeapSizing,
453 "attempt heap expansion",
454 ergo_format_reason("humongous allocation request failed")
455 ergo_format_byte("allocation request"),
456 word_size * HeapWordSize);
457
458 _hrm.expand_at(first, obj_regions);
459 g1_policy()->record_new_heap_size(num_regions());
460
461 #ifdef ASSERT
462 for (uint i = first; i < first + obj_regions; ++i) {
463 HeapRegion* hr = region_at(i);
464 assert(hr->is_free(), "sanity");
465 assert(hr->is_empty(), "sanity");
466 assert(is_on_master_free_list(hr), "sanity");
467 }
468 #endif
469 _hrm.allocate_free_regions_starting_at(first, obj_regions);
470 } else {
471 // Policy: Potentially trigger a defragmentation GC.
472 }
473 }
474
475 HeapWord* result = NULL;
476 if (first != G1_NO_HRM_INDEX) {
477 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
478 word_size, context);
479 assert(result != NULL, "it should always return a valid result");
480
481 // A successful humongous object allocation changes the used space
482 // information of the old generation so we need to recalculate the
483 // sizes and update the jstat counters here.
484 g1mm()->update_sizes();
485 }
486
487 verify_region_sets_optional();
488
489 return result;
490 }
491
492 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
493 assert_heap_not_locked_and_not_at_safepoint();
494 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
495
496 uint dummy_gc_count_before;
497 uint dummy_gclocker_retry_count = 0;
498 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
499 }
500
501 HeapWord*
502 G1CollectedHeap::mem_allocate(size_t word_size,
503 bool* gc_overhead_limit_was_exceeded) {
504 assert_heap_not_locked_and_not_at_safepoint();
505
506 // Loop until the allocation is satisfied, or unsatisfied after GC.
507 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
508 uint gc_count_before;
509
510 HeapWord* result = NULL;
511 if (!is_humongous(word_size)) {
512 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
513 } else {
514 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
515 }
516 if (result != NULL) {
517 return result;
518 }
519
520 // Create the garbage collection operation...
521 VM_G1CollectForAllocation op(gc_count_before, word_size);
522 op.set_allocation_context(AllocationContext::current());
523
524 // ...and get the VM thread to execute it.
525 VMThread::execute(&op);
526
527 if (op.prologue_succeeded() && op.pause_succeeded()) {
528 // If the operation was successful we'll return the result even
529 // if it is NULL. If the allocation attempt failed immediately
530 // after a Full GC, it's unlikely we'll be able to allocate now.
531 HeapWord* result = op.result();
532 if (result != NULL && !is_humongous(word_size)) {
533 // Allocations that take place on VM operations do not do any
534 // card dirtying and we have to do it here. We only have to do
535 // this for non-humongous allocations, though.
536 dirty_young_block(result, word_size);
537 }
538 return result;
539 } else {
540 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
541 return NULL;
542 }
543 assert(op.result() == NULL,
544 "the result should be NULL if the VM op did not succeed");
545 }
546
547 // Give a warning if we seem to be looping forever.
548 if ((QueuedAllocationWarningCount > 0) &&
549 (try_count % QueuedAllocationWarningCount == 0)) {
550 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
551 }
552 }
553
554 ShouldNotReachHere();
555 return NULL;
556 }
557
558 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
559 AllocationContext_t context,
560 uint* gc_count_before_ret,
561 uint* gclocker_retry_count_ret) {
562 // Make sure you read the note in attempt_allocation_humongous().
563
564 assert_heap_not_locked_and_not_at_safepoint();
565 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
566 "be called for humongous allocation requests");
567
568 // We should only get here after the first-level allocation attempt
569 // (attempt_allocation()) failed to allocate.
570
571 // We will loop until a) we manage to successfully perform the
572 // allocation or b) we successfully schedule a collection which
573 // fails to perform the allocation. b) is the only case when we'll
574 // return NULL.
575 HeapWord* result = NULL;
576 for (int try_count = 1; /* we'll return */; try_count += 1) {
577 bool should_try_gc;
578 uint gc_count_before;
579
580 {
581 MutexLockerEx x(Heap_lock);
582 result = _allocator->attempt_allocation_locked(word_size, context);
583 if (result != NULL) {
584 return result;
585 }
586
587 if (GC_locker::is_active_and_needs_gc()) {
588 if (g1_policy()->can_expand_young_list()) {
589 // No need for an ergo verbose message here,
590 // can_expand_young_list() does this when it returns true.
591 result = _allocator->attempt_allocation_force(word_size, context);
592 if (result != NULL) {
593 return result;
594 }
595 }
596 should_try_gc = false;
597 } else {
598 // The GCLocker may not be active but the GCLocker initiated
599 // GC may not yet have been performed (GCLocker::needs_gc()
600 // returns true). In this case we do not try this GC and
601 // wait until the GCLocker initiated GC is performed, and
602 // then retry the allocation.
603 if (GC_locker::needs_gc()) {
604 should_try_gc = false;
605 } else {
606 // Read the GC count while still holding the Heap_lock.
607 gc_count_before = total_collections();
608 should_try_gc = true;
609 }
610 }
611 }
612
613 if (should_try_gc) {
614 bool succeeded;
615 result = do_collection_pause(word_size, gc_count_before, &succeeded,
616 GCCause::_g1_inc_collection_pause);
617 if (result != NULL) {
618 assert(succeeded, "only way to get back a non-NULL result");
619 return result;
620 }
621
622 if (succeeded) {
623 // If we get here we successfully scheduled a collection which
624 // failed to allocate. No point in trying to allocate
625 // further. We'll just return NULL.
626 MutexLockerEx x(Heap_lock);
627 *gc_count_before_ret = total_collections();
628 return NULL;
629 }
630 } else {
631 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
632 MutexLockerEx x(Heap_lock);
633 *gc_count_before_ret = total_collections();
634 return NULL;
635 }
636 // The GCLocker is either active or the GCLocker initiated
637 // GC has not yet been performed. Stall until it is and
638 // then retry the allocation.
639 GC_locker::stall_until_clear();
640 (*gclocker_retry_count_ret) += 1;
641 }
642
643 // We can reach here if we were unsuccessful in scheduling a
644 // collection (because another thread beat us to it) or if we were
645 // stalled due to the GC locker. In either can we should retry the
646 // allocation attempt in case another thread successfully
647 // performed a collection and reclaimed enough space. We do the
648 // first attempt (without holding the Heap_lock) here and the
649 // follow-on attempt will be at the start of the next loop
650 // iteration (after taking the Heap_lock).
651 result = _allocator->attempt_allocation(word_size, context);
652 if (result != NULL) {
653 return result;
654 }
655
656 // Give a warning if we seem to be looping forever.
657 if ((QueuedAllocationWarningCount > 0) &&
658 (try_count % QueuedAllocationWarningCount == 0)) {
659 warning("G1CollectedHeap::attempt_allocation_slow() "
660 "retries %d times", try_count);
661 }
662 }
663
664 ShouldNotReachHere();
665 return NULL;
666 }
667
668 void G1CollectedHeap::begin_archive_alloc_range() {
669 assert_at_safepoint(true /* should_be_vm_thread */);
670 if (_archive_allocator == NULL) {
671 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
672 }
673 }
674
675 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
676 // Allocations in archive regions cannot be of a size that would be considered
677 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
678 // may be different at archive-restore time.
679 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
680 }
681
682 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
683 assert_at_safepoint(true /* should_be_vm_thread */);
684 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
685 if (is_archive_alloc_too_large(word_size)) {
686 return NULL;
687 }
688 return _archive_allocator->archive_mem_allocate(word_size);
689 }
690
691 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
692 size_t end_alignment_in_bytes) {
693 assert_at_safepoint(true /* should_be_vm_thread */);
694 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
695
696 // Call complete_archive to do the real work, filling in the MemRegion
697 // array with the archive regions.
698 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
699 delete _archive_allocator;
700 _archive_allocator = NULL;
701 }
702
703 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
704 assert(ranges != NULL, "MemRegion array NULL");
705 assert(count != 0, "No MemRegions provided");
706 MemRegion reserved = _hrm.reserved();
707 for (size_t i = 0; i < count; i++) {
708 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
709 return false;
710 }
711 }
712 return true;
713 }
714
715 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
716 assert(!is_init_completed(), "Expect to be called at JVM init time");
717 assert(ranges != NULL, "MemRegion array NULL");
718 assert(count != 0, "No MemRegions provided");
719 MutexLockerEx x(Heap_lock);
720
721 MemRegion reserved = _hrm.reserved();
722 HeapWord* prev_last_addr = NULL;
723 HeapRegion* prev_last_region = NULL;
724
725 // Temporarily disable pretouching of heap pages. This interface is used
726 // when mmap'ing archived heap data in, so pre-touching is wasted.
727 FlagSetting fs(AlwaysPreTouch, false);
728
729 // Enable archive object checking in G1MarkSweep. We have to let it know
730 // about each archive range, so that objects in those ranges aren't marked.
731 G1MarkSweep::enable_archive_object_check();
732
733 // For each specified MemRegion range, allocate the corresponding G1
734 // regions and mark them as archive regions. We expect the ranges in
735 // ascending starting address order, without overlap.
736 for (size_t i = 0; i < count; i++) {
737 MemRegion curr_range = ranges[i];
738 HeapWord* start_address = curr_range.start();
739 size_t word_size = curr_range.word_size();
740 HeapWord* last_address = curr_range.last();
741 size_t commits = 0;
742
743 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
744 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
745 p2i(start_address), p2i(last_address));
746 guarantee(start_address > prev_last_addr,
747 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
748 p2i(start_address), p2i(prev_last_addr));
749 prev_last_addr = last_address;
750
751 // Check for ranges that start in the same G1 region in which the previous
752 // range ended, and adjust the start address so we don't try to allocate
753 // the same region again. If the current range is entirely within that
754 // region, skip it, just adjusting the recorded top.
755 HeapRegion* start_region = _hrm.addr_to_region(start_address);
756 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
757 start_address = start_region->end();
758 if (start_address > last_address) {
759 increase_used(word_size * HeapWordSize);
760 start_region->set_top(last_address + 1);
761 continue;
762 }
763 start_region->set_top(start_address);
764 curr_range = MemRegion(start_address, last_address + 1);
765 start_region = _hrm.addr_to_region(start_address);
766 }
767
768 // Perform the actual region allocation, exiting if it fails.
769 // Then note how much new space we have allocated.
770 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
771 return false;
772 }
773 increase_used(word_size * HeapWordSize);
774 if (commits != 0) {
775 ergo_verbose1(ErgoHeapSizing,
776 "attempt heap expansion",
777 ergo_format_reason("allocate archive regions")
778 ergo_format_byte("total size"),
779 HeapRegion::GrainWords * HeapWordSize * commits);
780 }
781
782 // Mark each G1 region touched by the range as archive, add it to the old set,
783 // and set the allocation context and top.
784 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
785 HeapRegion* last_region = _hrm.addr_to_region(last_address);
786 prev_last_region = last_region;
787
788 while (curr_region != NULL) {
789 assert(curr_region->is_empty() && !curr_region->is_pinned(),
790 "Region already in use (index %u)", curr_region->hrm_index());
791 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
792 curr_region->set_allocation_context(AllocationContext::system());
793 curr_region->set_archive();
794 _old_set.add(curr_region);
795 if (curr_region != last_region) {
796 curr_region->set_top(curr_region->end());
797 curr_region = _hrm.next_region_in_heap(curr_region);
798 } else {
799 curr_region->set_top(last_address + 1);
800 curr_region = NULL;
801 }
802 }
803
804 // Notify mark-sweep of the archive range.
805 G1MarkSweep::set_range_archive(curr_range, true);
806 }
807 return true;
808 }
809
810 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
811 assert(!is_init_completed(), "Expect to be called at JVM init time");
812 assert(ranges != NULL, "MemRegion array NULL");
813 assert(count != 0, "No MemRegions provided");
814 MemRegion reserved = _hrm.reserved();
815 HeapWord *prev_last_addr = NULL;
816 HeapRegion* prev_last_region = NULL;
817
818 // For each MemRegion, create filler objects, if needed, in the G1 regions
819 // that contain the address range. The address range actually within the
820 // MemRegion will not be modified. That is assumed to have been initialized
821 // elsewhere, probably via an mmap of archived heap data.
822 MutexLockerEx x(Heap_lock);
823 for (size_t i = 0; i < count; i++) {
824 HeapWord* start_address = ranges[i].start();
825 HeapWord* last_address = ranges[i].last();
826
827 assert(reserved.contains(start_address) && reserved.contains(last_address),
828 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
829 p2i(start_address), p2i(last_address));
830 assert(start_address > prev_last_addr,
831 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
832 p2i(start_address), p2i(prev_last_addr));
833
834 HeapRegion* start_region = _hrm.addr_to_region(start_address);
835 HeapRegion* last_region = _hrm.addr_to_region(last_address);
836 HeapWord* bottom_address = start_region->bottom();
837
838 // Check for a range beginning in the same region in which the
839 // previous one ended.
840 if (start_region == prev_last_region) {
841 bottom_address = prev_last_addr + 1;
842 }
843
844 // Verify that the regions were all marked as archive regions by
845 // alloc_archive_regions.
846 HeapRegion* curr_region = start_region;
847 while (curr_region != NULL) {
848 guarantee(curr_region->is_archive(),
849 "Expected archive region at index %u", curr_region->hrm_index());
850 if (curr_region != last_region) {
851 curr_region = _hrm.next_region_in_heap(curr_region);
852 } else {
853 curr_region = NULL;
854 }
855 }
856
857 prev_last_addr = last_address;
858 prev_last_region = last_region;
859
860 // Fill the memory below the allocated range with dummy object(s),
861 // if the region bottom does not match the range start, or if the previous
862 // range ended within the same G1 region, and there is a gap.
863 if (start_address != bottom_address) {
864 size_t fill_size = pointer_delta(start_address, bottom_address);
865 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
866 increase_used(fill_size * HeapWordSize);
867 }
868 }
869 }
870
871 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
872 uint* gc_count_before_ret,
873 uint* gclocker_retry_count_ret) {
874 assert_heap_not_locked_and_not_at_safepoint();
875 assert(!is_humongous(word_size), "attempt_allocation() should not "
876 "be called for humongous allocation requests");
877
878 AllocationContext_t context = AllocationContext::current();
879 HeapWord* result = _allocator->attempt_allocation(word_size, context);
880
881 if (result == NULL) {
882 result = attempt_allocation_slow(word_size,
883 context,
884 gc_count_before_ret,
885 gclocker_retry_count_ret);
886 }
887 assert_heap_not_locked();
888 if (result != NULL) {
889 dirty_young_block(result, word_size);
890 }
891 return result;
892 }
893
894 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
895 assert(!is_init_completed(), "Expect to be called at JVM init time");
896 assert(ranges != NULL, "MemRegion array NULL");
897 assert(count != 0, "No MemRegions provided");
898 MemRegion reserved = _hrm.reserved();
899 HeapWord* prev_last_addr = NULL;
900 HeapRegion* prev_last_region = NULL;
901 size_t size_used = 0;
902 size_t uncommitted_regions = 0;
903
904 // For each Memregion, free the G1 regions that constitute it, and
905 // notify mark-sweep that the range is no longer to be considered 'archive.'
906 MutexLockerEx x(Heap_lock);
907 for (size_t i = 0; i < count; i++) {
908 HeapWord* start_address = ranges[i].start();
909 HeapWord* last_address = ranges[i].last();
910
911 assert(reserved.contains(start_address) && reserved.contains(last_address),
912 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
913 p2i(start_address), p2i(last_address));
914 assert(start_address > prev_last_addr,
915 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
916 p2i(start_address), p2i(prev_last_addr));
917 size_used += ranges[i].byte_size();
918 prev_last_addr = last_address;
919
920 HeapRegion* start_region = _hrm.addr_to_region(start_address);
921 HeapRegion* last_region = _hrm.addr_to_region(last_address);
922
923 // Check for ranges that start in the same G1 region in which the previous
924 // range ended, and adjust the start address so we don't try to free
925 // the same region again. If the current range is entirely within that
926 // region, skip it.
927 if (start_region == prev_last_region) {
928 start_address = start_region->end();
929 if (start_address > last_address) {
930 continue;
931 }
932 start_region = _hrm.addr_to_region(start_address);
933 }
934 prev_last_region = last_region;
935
936 // After verifying that each region was marked as an archive region by
937 // alloc_archive_regions, set it free and empty and uncommit it.
938 HeapRegion* curr_region = start_region;
939 while (curr_region != NULL) {
940 guarantee(curr_region->is_archive(),
941 "Expected archive region at index %u", curr_region->hrm_index());
942 uint curr_index = curr_region->hrm_index();
943 _old_set.remove(curr_region);
944 curr_region->set_free();
945 curr_region->set_top(curr_region->bottom());
946 if (curr_region != last_region) {
947 curr_region = _hrm.next_region_in_heap(curr_region);
948 } else {
949 curr_region = NULL;
950 }
951 _hrm.shrink_at(curr_index, 1);
952 uncommitted_regions++;
953 }
954
955 // Notify mark-sweep that this is no longer an archive range.
956 G1MarkSweep::set_range_archive(ranges[i], false);
957 }
958
959 if (uncommitted_regions != 0) {
960 ergo_verbose1(ErgoHeapSizing,
961 "attempt heap shrinking",
962 ergo_format_reason("uncommitted archive regions")
963 ergo_format_byte("total size"),
964 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
965 }
966 decrease_used(size_used);
967 }
968
969 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
970 uint* gc_count_before_ret,
971 uint* gclocker_retry_count_ret) {
972 // The structure of this method has a lot of similarities to
973 // attempt_allocation_slow(). The reason these two were not merged
974 // into a single one is that such a method would require several "if
975 // allocation is not humongous do this, otherwise do that"
976 // conditional paths which would obscure its flow. In fact, an early
977 // version of this code did use a unified method which was harder to
978 // follow and, as a result, it had subtle bugs that were hard to
979 // track down. So keeping these two methods separate allows each to
980 // be more readable. It will be good to keep these two in sync as
981 // much as possible.
982
983 assert_heap_not_locked_and_not_at_safepoint();
984 assert(is_humongous(word_size), "attempt_allocation_humongous() "
985 "should only be called for humongous allocations");
986
987 // Humongous objects can exhaust the heap quickly, so we should check if we
988 // need to start a marking cycle at each humongous object allocation. We do
989 // the check before we do the actual allocation. The reason for doing it
990 // before the allocation is that we avoid having to keep track of the newly
991 // allocated memory while we do a GC.
992 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
993 word_size)) {
994 collect(GCCause::_g1_humongous_allocation);
995 }
996
997 // We will loop until a) we manage to successfully perform the
998 // allocation or b) we successfully schedule a collection which
999 // fails to perform the allocation. b) is the only case when we'll
1000 // return NULL.
1001 HeapWord* result = NULL;
1002 for (int try_count = 1; /* we'll return */; try_count += 1) {
1003 bool should_try_gc;
1004 uint gc_count_before;
1005
1006 {
1007 MutexLockerEx x(Heap_lock);
1008
1009 // Given that humongous objects are not allocated in young
1010 // regions, we'll first try to do the allocation without doing a
1011 // collection hoping that there's enough space in the heap.
1012 result = humongous_obj_allocate(word_size, AllocationContext::current());
1013 if (result != NULL) {
1014 return result;
1015 }
1016
1017 if (GC_locker::is_active_and_needs_gc()) {
1018 should_try_gc = false;
1019 } else {
1020 // The GCLocker may not be active but the GCLocker initiated
1021 // GC may not yet have been performed (GCLocker::needs_gc()
1022 // returns true). In this case we do not try this GC and
1023 // wait until the GCLocker initiated GC is performed, and
1024 // then retry the allocation.
1025 if (GC_locker::needs_gc()) {
1026 should_try_gc = false;
1027 } else {
1028 // Read the GC count while still holding the Heap_lock.
1029 gc_count_before = total_collections();
1030 should_try_gc = true;
1031 }
1032 }
1033 }
1034
1035 if (should_try_gc) {
1036 // If we failed to allocate the humongous object, we should try to
1037 // do a collection pause (if we're allowed) in case it reclaims
1038 // enough space for the allocation to succeed after the pause.
1039
1040 bool succeeded;
1041 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1042 GCCause::_g1_humongous_allocation);
1043 if (result != NULL) {
1044 assert(succeeded, "only way to get back a non-NULL result");
1045 return result;
1046 }
1047
1048 if (succeeded) {
1049 // If we get here we successfully scheduled a collection which
1050 // failed to allocate. No point in trying to allocate
1051 // further. We'll just return NULL.
1052 MutexLockerEx x(Heap_lock);
1053 *gc_count_before_ret = total_collections();
1054 return NULL;
1055 }
1056 } else {
1057 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1058 MutexLockerEx x(Heap_lock);
1059 *gc_count_before_ret = total_collections();
1060 return NULL;
1061 }
1062 // The GCLocker is either active or the GCLocker initiated
1063 // GC has not yet been performed. Stall until it is and
1064 // then retry the allocation.
1065 GC_locker::stall_until_clear();
1066 (*gclocker_retry_count_ret) += 1;
1067 }
1068
1069 // We can reach here if we were unsuccessful in scheduling a
1070 // collection (because another thread beat us to it) or if we were
1071 // stalled due to the GC locker. In either can we should retry the
1072 // allocation attempt in case another thread successfully
1073 // performed a collection and reclaimed enough space. Give a
1074 // warning if we seem to be looping forever.
1075
1076 if ((QueuedAllocationWarningCount > 0) &&
1077 (try_count % QueuedAllocationWarningCount == 0)) {
1078 warning("G1CollectedHeap::attempt_allocation_humongous() "
1079 "retries %d times", try_count);
1080 }
1081 }
1082
1083 ShouldNotReachHere();
1084 return NULL;
1085 }
1086
1087 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1088 AllocationContext_t context,
1089 bool expect_null_mutator_alloc_region) {
1090 assert_at_safepoint(true /* should_be_vm_thread */);
1091 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1092 "the current alloc region was unexpectedly found to be non-NULL");
1093
1094 if (!is_humongous(word_size)) {
1095 return _allocator->attempt_allocation_locked(word_size, context);
1096 } else {
1097 HeapWord* result = humongous_obj_allocate(word_size, context);
1098 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1099 collector_state()->set_initiate_conc_mark_if_possible(true);
1100 }
1101 return result;
1102 }
1103
1104 ShouldNotReachHere();
1105 }
1106
1107 class PostMCRemSetClearClosure: public HeapRegionClosure {
1108 G1CollectedHeap* _g1h;
1109 ModRefBarrierSet* _mr_bs;
1110 public:
1111 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1112 _g1h(g1h), _mr_bs(mr_bs) {}
1113
1114 bool doHeapRegion(HeapRegion* r) {
1115 HeapRegionRemSet* hrrs = r->rem_set();
1116
1117 _g1h->reset_gc_time_stamps(r);
1118
1119 if (r->is_continues_humongous()) {
1120 // We'll assert that the strong code root list and RSet is empty
1121 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1122 assert(hrrs->occupied() == 0, "RSet should be empty");
1123 } else {
1124 hrrs->clear();
1125 }
1126 // You might think here that we could clear just the cards
1127 // corresponding to the used region. But no: if we leave a dirty card
1128 // in a region we might allocate into, then it would prevent that card
1129 // from being enqueued, and cause it to be missed.
1130 // Re: the performance cost: we shouldn't be doing full GC anyway!
1131 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1132
1133 return false;
1134 }
1135 };
1136
1137 void G1CollectedHeap::clear_rsets_post_compaction() {
1138 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1139 heap_region_iterate(&rs_clear);
1140 }
1141
1142 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1143 G1CollectedHeap* _g1h;
1144 UpdateRSOopClosure _cl;
1145 public:
1146 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1147 _cl(g1->g1_rem_set(), worker_i),
1148 _g1h(g1)
1149 { }
1150
1151 bool doHeapRegion(HeapRegion* r) {
1152 if (!r->is_continues_humongous()) {
1153 _cl.set_from(r);
1154 r->oop_iterate(&_cl);
1155 }
1156 return false;
1157 }
1158 };
1159
1160 class ParRebuildRSTask: public AbstractGangTask {
1161 G1CollectedHeap* _g1;
1162 HeapRegionClaimer _hrclaimer;
1163
1164 public:
1165 ParRebuildRSTask(G1CollectedHeap* g1) :
1166 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1167
1168 void work(uint worker_id) {
1169 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1170 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1171 }
1172 };
1173
1174 class PostCompactionPrinterClosure: public HeapRegionClosure {
1175 private:
1176 G1HRPrinter* _hr_printer;
1177 public:
1178 bool doHeapRegion(HeapRegion* hr) {
1179 assert(!hr->is_young(), "not expecting to find young regions");
1180 if (hr->is_free()) {
1181 // We only generate output for non-empty regions.
1182 } else if (hr->is_starts_humongous()) {
1183 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1184 } else if (hr->is_continues_humongous()) {
1185 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1186 } else if (hr->is_archive()) {
1187 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1188 } else if (hr->is_old()) {
1189 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1190 } else {
1191 ShouldNotReachHere();
1192 }
1193 return false;
1194 }
1195
1196 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1197 : _hr_printer(hr_printer) { }
1198 };
1199
1200 void G1CollectedHeap::print_hrm_post_compaction() {
1201 PostCompactionPrinterClosure cl(hr_printer());
1202 heap_region_iterate(&cl);
1203 }
1204
1205 bool G1CollectedHeap::do_collection(bool explicit_gc,
1206 bool clear_all_soft_refs,
1207 size_t word_size) {
1208 assert_at_safepoint(true /* should_be_vm_thread */);
1209
1210 if (GC_locker::check_active_before_gc()) {
1211 return false;
1212 }
1213
1214 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1215 gc_timer->register_gc_start();
1216
1217 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1218 GCIdMark gc_id_mark;
1219 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1220
1221 SvcGCMarker sgcm(SvcGCMarker::FULL);
1222 ResourceMark rm;
1223
1224 G1Log::update_level();
1225 print_heap_before_gc();
1226 trace_heap_before_gc(gc_tracer);
1227
1228 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1229
1230 verify_region_sets_optional();
1231
1232 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1233 collector_policy()->should_clear_all_soft_refs();
1234
1235 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1236
1237 {
1238 IsGCActiveMark x;
1239
1240 // Timing
1241 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1242 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1243
1244 {
1245 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1246 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1247 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1248
1249 g1_policy()->record_full_collection_start();
1250
1251 // Note: When we have a more flexible GC logging framework that
1252 // allows us to add optional attributes to a GC log record we
1253 // could consider timing and reporting how long we wait in the
1254 // following two methods.
1255 wait_while_free_regions_coming();
1256 // If we start the compaction before the CM threads finish
1257 // scanning the root regions we might trip them over as we'll
1258 // be moving objects / updating references. So let's wait until
1259 // they are done. By telling them to abort, they should complete
1260 // early.
1261 _cm->root_regions()->abort();
1262 _cm->root_regions()->wait_until_scan_finished();
1263 append_secondary_free_list_if_not_empty_with_lock();
1264
1265 gc_prologue(true);
1266 increment_total_collections(true /* full gc */);
1267 increment_old_marking_cycles_started();
1268
1269 assert(used() == recalculate_used(), "Should be equal");
1270
1271 verify_before_gc();
1272
1273 check_bitmaps("Full GC Start");
1274 pre_full_gc_dump(gc_timer);
1275
1276 #if defined(COMPILER2) || INCLUDE_JVMCI
1277 DerivedPointerTable::clear();
1278 #endif
1279
1280 // Disable discovery and empty the discovered lists
1281 // for the CM ref processor.
1282 ref_processor_cm()->disable_discovery();
1283 ref_processor_cm()->abandon_partial_discovery();
1284 ref_processor_cm()->verify_no_references_recorded();
1285
1286 // Abandon current iterations of concurrent marking and concurrent
1287 // refinement, if any are in progress. We have to do this before
1288 // wait_until_scan_finished() below.
1289 concurrent_mark()->abort();
1290
1291 // Make sure we'll choose a new allocation region afterwards.
1292 _allocator->release_mutator_alloc_region();
1293 _allocator->abandon_gc_alloc_regions();
1294 g1_rem_set()->cleanupHRRS();
1295
1296 // We should call this after we retire any currently active alloc
1297 // regions so that all the ALLOC / RETIRE events are generated
1298 // before the start GC event.
1299 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1300
1301 // We may have added regions to the current incremental collection
1302 // set between the last GC or pause and now. We need to clear the
1303 // incremental collection set and then start rebuilding it afresh
1304 // after this full GC.
1305 abandon_collection_set(g1_policy()->inc_cset_head());
1306 g1_policy()->clear_incremental_cset();
1307 g1_policy()->stop_incremental_cset_building();
1308
1309 tear_down_region_sets(false /* free_list_only */);
1310 collector_state()->set_gcs_are_young(true);
1311
1312 // See the comments in g1CollectedHeap.hpp and
1313 // G1CollectedHeap::ref_processing_init() about
1314 // how reference processing currently works in G1.
1315
1316 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1317 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1318
1319 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1320 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1321
1322 ref_processor_stw()->enable_discovery();
1323 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1324
1325 // Do collection work
1326 {
1327 HandleMark hm; // Discard invalid handles created during gc
1328 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1329 }
1330
1331 assert(num_free_regions() == 0, "we should not have added any free regions");
1332 rebuild_region_sets(false /* free_list_only */);
1333
1334 // Enqueue any discovered reference objects that have
1335 // not been removed from the discovered lists.
1336 ref_processor_stw()->enqueue_discovered_references();
1337
1338 #if defined(COMPILER2) || INCLUDE_JVMCI
1339 DerivedPointerTable::update_pointers();
1340 #endif
1341
1342 MemoryService::track_memory_usage();
1343
1344 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1345 ref_processor_stw()->verify_no_references_recorded();
1346
1347 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1348 ClassLoaderDataGraph::purge();
1349 MetaspaceAux::verify_metrics();
1350
1351 // Note: since we've just done a full GC, concurrent
1352 // marking is no longer active. Therefore we need not
1353 // re-enable reference discovery for the CM ref processor.
1354 // That will be done at the start of the next marking cycle.
1355 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1356 ref_processor_cm()->verify_no_references_recorded();
1357
1358 reset_gc_time_stamp();
1359 // Since everything potentially moved, we will clear all remembered
1360 // sets, and clear all cards. Later we will rebuild remembered
1361 // sets. We will also reset the GC time stamps of the regions.
1362 clear_rsets_post_compaction();
1363 check_gc_time_stamps();
1364
1365 // Resize the heap if necessary.
1366 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1367
1368 if (_hr_printer.is_active()) {
1369 // We should do this after we potentially resize the heap so
1370 // that all the COMMIT / UNCOMMIT events are generated before
1371 // the end GC event.
1372
1373 print_hrm_post_compaction();
1374 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1375 }
1376
1377 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1378 if (hot_card_cache->use_cache()) {
1379 hot_card_cache->reset_card_counts();
1380 hot_card_cache->reset_hot_cache();
1381 }
1382
1383 // Rebuild remembered sets of all regions.
1384 uint n_workers =
1385 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1386 workers()->active_workers(),
1387 Threads::number_of_non_daemon_threads());
1388 workers()->set_active_workers(n_workers);
1389
1390 ParRebuildRSTask rebuild_rs_task(this);
1391 workers()->run_task(&rebuild_rs_task);
1392
1393 // Rebuild the strong code root lists for each region
1394 rebuild_strong_code_roots();
1395
1396 if (true) { // FIXME
1397 MetaspaceGC::compute_new_size();
1398 }
1399
1400 #ifdef TRACESPINNING
1401 ParallelTaskTerminator::print_termination_counts();
1402 #endif
1403
1404 // Discard all rset updates
1405 JavaThread::dirty_card_queue_set().abandon_logs();
1406 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1407
1408 _young_list->reset_sampled_info();
1409 // At this point there should be no regions in the
1410 // entire heap tagged as young.
1411 assert(check_young_list_empty(true /* check_heap */),
1412 "young list should be empty at this point");
1413
1414 // Update the number of full collections that have been completed.
1415 increment_old_marking_cycles_completed(false /* concurrent */);
1416
1417 _hrm.verify_optional();
1418 verify_region_sets_optional();
1419
1420 verify_after_gc();
1421
1422 // Clear the previous marking bitmap, if needed for bitmap verification.
1423 // Note we cannot do this when we clear the next marking bitmap in
1424 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1425 // objects marked during a full GC against the previous bitmap.
1426 // But we need to clear it before calling check_bitmaps below since
1427 // the full GC has compacted objects and updated TAMS but not updated
1428 // the prev bitmap.
1429 if (G1VerifyBitmaps) {
1430 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1431 }
1432 check_bitmaps("Full GC End");
1433
1434 // Start a new incremental collection set for the next pause
1435 assert(g1_policy()->collection_set() == NULL, "must be");
1436 g1_policy()->start_incremental_cset_building();
1437
1438 clear_cset_fast_test();
1439
1440 _allocator->init_mutator_alloc_region();
1441
1442 g1_policy()->record_full_collection_end();
1443
1444 if (G1Log::fine()) {
1445 g1_policy()->print_heap_transition();
1446 }
1447
1448 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1449 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1450 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1451 // before any GC notifications are raised.
1452 g1mm()->update_sizes();
1453
1454 gc_epilogue(true);
1455 }
1456
1457 if (G1Log::finer()) {
1458 g1_policy()->print_detailed_heap_transition(true /* full */);
1459 }
1460
1461 print_heap_after_gc();
1462 trace_heap_after_gc(gc_tracer);
1463
1464 post_full_gc_dump(gc_timer);
1465
1466 gc_timer->register_gc_end();
1467 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1468 }
1469
1470 return true;
1471 }
1472
1473 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1474 // do_collection() will return whether it succeeded in performing
1475 // the GC. Currently, there is no facility on the
1476 // do_full_collection() API to notify the caller than the collection
1477 // did not succeed (e.g., because it was locked out by the GC
1478 // locker). So, right now, we'll ignore the return value.
1479 bool dummy = do_collection(true, /* explicit_gc */
1480 clear_all_soft_refs,
1481 0 /* word_size */);
1482 }
1483
1484 // This code is mostly copied from TenuredGeneration.
1485 void
1486 G1CollectedHeap::
1487 resize_if_necessary_after_full_collection(size_t word_size) {
1488 // Include the current allocation, if any, and bytes that will be
1489 // pre-allocated to support collections, as "used".
1490 const size_t used_after_gc = used();
1491 const size_t capacity_after_gc = capacity();
1492 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1493
1494 // This is enforced in arguments.cpp.
1495 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1496 "otherwise the code below doesn't make sense");
1497
1498 // We don't have floating point command-line arguments
1499 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1500 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1501 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1502 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1503
1504 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1505 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1506
1507 // We have to be careful here as these two calculations can overflow
1508 // 32-bit size_t's.
1509 double used_after_gc_d = (double) used_after_gc;
1510 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1511 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1512
1513 // Let's make sure that they are both under the max heap size, which
1514 // by default will make them fit into a size_t.
1515 double desired_capacity_upper_bound = (double) max_heap_size;
1516 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1517 desired_capacity_upper_bound);
1518 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1519 desired_capacity_upper_bound);
1520
1521 // We can now safely turn them into size_t's.
1522 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1523 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1524
1525 // This assert only makes sense here, before we adjust them
1526 // with respect to the min and max heap size.
1527 assert(minimum_desired_capacity <= maximum_desired_capacity,
1528 "minimum_desired_capacity = " SIZE_FORMAT ", "
1529 "maximum_desired_capacity = " SIZE_FORMAT,
1530 minimum_desired_capacity, maximum_desired_capacity);
1531
1532 // Should not be greater than the heap max size. No need to adjust
1533 // it with respect to the heap min size as it's a lower bound (i.e.,
1534 // we'll try to make the capacity larger than it, not smaller).
1535 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1536 // Should not be less than the heap min size. No need to adjust it
1537 // with respect to the heap max size as it's an upper bound (i.e.,
1538 // we'll try to make the capacity smaller than it, not greater).
1539 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1540
1541 if (capacity_after_gc < minimum_desired_capacity) {
1542 // Don't expand unless it's significant
1543 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1544 ergo_verbose4(ErgoHeapSizing,
1545 "attempt heap expansion",
1546 ergo_format_reason("capacity lower than "
1547 "min desired capacity after Full GC")
1548 ergo_format_byte("capacity")
1549 ergo_format_byte("occupancy")
1550 ergo_format_byte_perc("min desired capacity"),
1551 capacity_after_gc, used_after_gc,
1552 minimum_desired_capacity, (double) MinHeapFreeRatio);
1553 expand(expand_bytes);
1554
1555 // No expansion, now see if we want to shrink
1556 } else if (capacity_after_gc > maximum_desired_capacity) {
1557 // Capacity too large, compute shrinking size
1558 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1559 ergo_verbose4(ErgoHeapSizing,
1560 "attempt heap shrinking",
1561 ergo_format_reason("capacity higher than "
1562 "max desired capacity after Full GC")
1563 ergo_format_byte("capacity")
1564 ergo_format_byte("occupancy")
1565 ergo_format_byte_perc("max desired capacity"),
1566 capacity_after_gc, used_after_gc,
1567 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1568 shrink(shrink_bytes);
1569 }
1570 }
1571
1572 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1573 AllocationContext_t context,
1574 bool do_gc,
1575 bool clear_all_soft_refs,
1576 bool expect_null_mutator_alloc_region,
1577 bool* gc_succeeded) {
1578 *gc_succeeded = true;
1579 // Let's attempt the allocation first.
1580 HeapWord* result =
1581 attempt_allocation_at_safepoint(word_size,
1582 context,
1583 expect_null_mutator_alloc_region);
1584 if (result != NULL) {
1585 assert(*gc_succeeded, "sanity");
1586 return result;
1587 }
1588
1589 // In a G1 heap, we're supposed to keep allocation from failing by
1590 // incremental pauses. Therefore, at least for now, we'll favor
1591 // expansion over collection. (This might change in the future if we can
1592 // do something smarter than full collection to satisfy a failed alloc.)
1593 result = expand_and_allocate(word_size, context);
1594 if (result != NULL) {
1595 assert(*gc_succeeded, "sanity");
1596 return result;
1597 }
1598
1599 if (do_gc) {
1600 // Expansion didn't work, we'll try to do a Full GC.
1601 *gc_succeeded = do_collection(false, /* explicit_gc */
1602 clear_all_soft_refs,
1603 word_size);
1604 }
1605
1606 return NULL;
1607 }
1608
1609 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1610 AllocationContext_t context,
1611 bool* succeeded) {
1612 assert_at_safepoint(true /* should_be_vm_thread */);
1613
1614 // Attempts to allocate followed by Full GC.
1615 HeapWord* result =
1616 satisfy_failed_allocation_helper(word_size,
1617 context,
1618 true, /* do_gc */
1619 false, /* clear_all_soft_refs */
1620 false, /* expect_null_mutator_alloc_region */
1621 succeeded);
1622
1623 if (result != NULL || !*succeeded) {
1624 return result;
1625 }
1626
1627 // Attempts to allocate followed by Full GC that will collect all soft references.
1628 result = satisfy_failed_allocation_helper(word_size,
1629 context,
1630 true, /* do_gc */
1631 true, /* clear_all_soft_refs */
1632 true, /* expect_null_mutator_alloc_region */
1633 succeeded);
1634
1635 if (result != NULL || !*succeeded) {
1636 return result;
1637 }
1638
1639 // Attempts to allocate, no GC
1640 result = satisfy_failed_allocation_helper(word_size,
1641 context,
1642 false, /* do_gc */
1643 false, /* clear_all_soft_refs */
1644 true, /* expect_null_mutator_alloc_region */
1645 succeeded);
1646
1647 if (result != NULL) {
1648 assert(*succeeded, "sanity");
1649 return result;
1650 }
1651
1652 assert(!collector_policy()->should_clear_all_soft_refs(),
1653 "Flag should have been handled and cleared prior to this point");
1654
1655 // What else? We might try synchronous finalization later. If the total
1656 // space available is large enough for the allocation, then a more
1657 // complete compaction phase than we've tried so far might be
1658 // appropriate.
1659 assert(*succeeded, "sanity");
1660 return NULL;
1661 }
1662
1663 // Attempting to expand the heap sufficiently
1664 // to support an allocation of the given "word_size". If
1665 // successful, perform the allocation and return the address of the
1666 // allocated block, or else "NULL".
1667
1668 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1669 assert_at_safepoint(true /* should_be_vm_thread */);
1670
1671 verify_region_sets_optional();
1672
1673 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1674 ergo_verbose1(ErgoHeapSizing,
1675 "attempt heap expansion",
1676 ergo_format_reason("allocation request failed")
1677 ergo_format_byte("allocation request"),
1678 word_size * HeapWordSize);
1679 if (expand(expand_bytes)) {
1680 _hrm.verify_optional();
1681 verify_region_sets_optional();
1682 return attempt_allocation_at_safepoint(word_size,
1683 context,
1684 false /* expect_null_mutator_alloc_region */);
1685 }
1686 return NULL;
1687 }
1688
1689 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1690 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1691 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1692 HeapRegion::GrainBytes);
1693 ergo_verbose2(ErgoHeapSizing,
1694 "expand the heap",
1695 ergo_format_byte("requested expansion amount")
1696 ergo_format_byte("attempted expansion amount"),
1697 expand_bytes, aligned_expand_bytes);
1698
1699 if (is_maximal_no_gc()) {
1700 ergo_verbose0(ErgoHeapSizing,
1701 "did not expand the heap",
1702 ergo_format_reason("heap already fully expanded"));
1703 return false;
1704 }
1705
1706 double expand_heap_start_time_sec = os::elapsedTime();
1707 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1708 assert(regions_to_expand > 0, "Must expand by at least one region");
1709
1710 uint expanded_by = _hrm.expand_by(regions_to_expand);
1711 if (expand_time_ms != NULL) {
1712 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1713 }
1714
1715 if (expanded_by > 0) {
1716 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1717 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1718 g1_policy()->record_new_heap_size(num_regions());
1719 } else {
1720 ergo_verbose0(ErgoHeapSizing,
1721 "did not expand the heap",
1722 ergo_format_reason("heap expansion operation failed"));
1723 // The expansion of the virtual storage space was unsuccessful.
1724 // Let's see if it was because we ran out of swap.
1725 if (G1ExitOnExpansionFailure &&
1726 _hrm.available() >= regions_to_expand) {
1727 // We had head room...
1728 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1729 }
1730 }
1731 return regions_to_expand > 0;
1732 }
1733
1734 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1735 size_t aligned_shrink_bytes =
1736 ReservedSpace::page_align_size_down(shrink_bytes);
1737 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1738 HeapRegion::GrainBytes);
1739 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1740
1741 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1742 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1743
1744 ergo_verbose3(ErgoHeapSizing,
1745 "shrink the heap",
1746 ergo_format_byte("requested shrinking amount")
1747 ergo_format_byte("aligned shrinking amount")
1748 ergo_format_byte("attempted shrinking amount"),
1749 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1750 if (num_regions_removed > 0) {
1751 g1_policy()->record_new_heap_size(num_regions());
1752 } else {
1753 ergo_verbose0(ErgoHeapSizing,
1754 "did not shrink the heap",
1755 ergo_format_reason("heap shrinking operation failed"));
1756 }
1757 }
1758
1759 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1760 verify_region_sets_optional();
1761
1762 // We should only reach here at the end of a Full GC which means we
1763 // should not not be holding to any GC alloc regions. The method
1764 // below will make sure of that and do any remaining clean up.
1765 _allocator->abandon_gc_alloc_regions();
1766
1767 // Instead of tearing down / rebuilding the free lists here, we
1768 // could instead use the remove_all_pending() method on free_list to
1769 // remove only the ones that we need to remove.
1770 tear_down_region_sets(true /* free_list_only */);
1771 shrink_helper(shrink_bytes);
1772 rebuild_region_sets(true /* free_list_only */);
1773
1774 _hrm.verify_optional();
1775 verify_region_sets_optional();
1776 }
1777
1778 // Public methods.
1779
1780 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1781 CollectedHeap(),
1782 _g1_policy(policy_),
1783 _dirty_card_queue_set(false),
1784 _is_alive_closure_cm(this),
1785 _is_alive_closure_stw(this),
1786 _ref_processor_cm(NULL),
1787 _ref_processor_stw(NULL),
1788 _bot_shared(NULL),
1789 _cg1r(NULL),
1790 _g1mm(NULL),
1791 _refine_cte_cl(NULL),
1792 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1793 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1794 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1795 _humongous_reclaim_candidates(),
1796 _has_humongous_reclaim_candidates(false),
1797 _archive_allocator(NULL),
1798 _free_regions_coming(false),
1799 _young_list(new YoungList(this)),
1800 _gc_time_stamp(0),
1801 _summary_bytes_used(0),
1802 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1803 _old_evac_stats(OldPLABSize, PLABWeight),
1804 _expand_heap_after_alloc_failure(true),
1805 _old_marking_cycles_started(0),
1806 _old_marking_cycles_completed(0),
1807 _heap_summary_sent(false),
1808 _in_cset_fast_test(),
1809 _dirty_cards_region_list(NULL),
1810 _worker_cset_start_region(NULL),
1811 _worker_cset_start_region_time_stamp(NULL),
1812 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1813 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1814 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1815 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1816
1817 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1818 /* are_GC_task_threads */true,
1819 /* are_ConcurrentGC_threads */false);
1820 _workers->initialize_workers();
1821
1822 _allocator = G1Allocator::create_allocator(this);
1823 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1824
1825 // Override the default _filler_array_max_size so that no humongous filler
1826 // objects are created.
1827 _filler_array_max_size = _humongous_object_threshold_in_words;
1828
1829 uint n_queues = ParallelGCThreads;
1830 _task_queues = new RefToScanQueueSet(n_queues);
1831
1832 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1833 assert(n_rem_sets > 0, "Invariant.");
1834
1835 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1836 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1837 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1838
1839 for (uint i = 0; i < n_queues; i++) {
1840 RefToScanQueue* q = new RefToScanQueue();
1841 q->initialize();
1842 _task_queues->register_queue(i, q);
1843 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1844 }
1845 clear_cset_start_regions();
1846
1847 // Initialize the G1EvacuationFailureALot counters and flags.
1848 NOT_PRODUCT(reset_evacuation_should_fail();)
1849
1850 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1851 }
1852
1853 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1854 size_t size,
1855 size_t translation_factor) {
1856 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1857 // Allocate a new reserved space, preferring to use large pages.
1858 ReservedSpace rs(size, preferred_page_size);
1859 G1RegionToSpaceMapper* result =
1860 G1RegionToSpaceMapper::create_mapper(rs,
1861 size,
1862 rs.alignment(),
1863 HeapRegion::GrainBytes,
1864 translation_factor,
1865 mtGC);
1866 if (TracePageSizes) {
1867 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1868 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1869 }
1870 return result;
1871 }
1872
1873 jint G1CollectedHeap::initialize() {
1874 CollectedHeap::pre_initialize();
1875 os::enable_vtime();
1876
1877 G1Log::init();
1878
1879 // Necessary to satisfy locking discipline assertions.
1880
1881 MutexLocker x(Heap_lock);
1882
1883 // We have to initialize the printer before committing the heap, as
1884 // it will be used then.
1885 _hr_printer.set_active(G1PrintHeapRegions);
1886
1887 // While there are no constraints in the GC code that HeapWordSize
1888 // be any particular value, there are multiple other areas in the
1889 // system which believe this to be true (e.g. oop->object_size in some
1890 // cases incorrectly returns the size in wordSize units rather than
1891 // HeapWordSize).
1892 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1893
1894 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1895 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1896 size_t heap_alignment = collector_policy()->heap_alignment();
1897
1898 // Ensure that the sizes are properly aligned.
1899 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1900 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1901 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1902
1903 _refine_cte_cl = new RefineCardTableEntryClosure();
1904
1905 jint ecode = JNI_OK;
1906 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1907 if (_cg1r == NULL) {
1908 return ecode;
1909 }
1910
1911 // Reserve the maximum.
1912
1913 // When compressed oops are enabled, the preferred heap base
1914 // is calculated by subtracting the requested size from the
1915 // 32Gb boundary and using the result as the base address for
1916 // heap reservation. If the requested size is not aligned to
1917 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1918 // into the ReservedHeapSpace constructor) then the actual
1919 // base of the reserved heap may end up differing from the
1920 // address that was requested (i.e. the preferred heap base).
1921 // If this happens then we could end up using a non-optimal
1922 // compressed oops mode.
1923
1924 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1925 heap_alignment);
1926
1927 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1928
1929 // Create the barrier set for the entire reserved region.
1930 G1SATBCardTableLoggingModRefBS* bs
1931 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1932 bs->initialize();
1933 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1934 set_barrier_set(bs);
1935
1936 // Also create a G1 rem set.
1937 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1938
1939 // Carve out the G1 part of the heap.
1940
1941 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1942 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1943 G1RegionToSpaceMapper* heap_storage =
1944 G1RegionToSpaceMapper::create_mapper(g1_rs,
1945 g1_rs.size(),
1946 page_size,
1947 HeapRegion::GrainBytes,
1948 1,
1949 mtJavaHeap);
1950 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1951 max_byte_size, page_size,
1952 heap_rs.base(),
1953 heap_rs.size());
1954 heap_storage->set_mapping_changed_listener(&_listener);
1955
1956 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1957 G1RegionToSpaceMapper* bot_storage =
1958 create_aux_memory_mapper("Block offset table",
1959 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1960 G1BlockOffsetSharedArray::heap_map_factor());
1961
1962 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1963 G1RegionToSpaceMapper* cardtable_storage =
1964 create_aux_memory_mapper("Card table",
1965 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1966 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1967
1968 G1RegionToSpaceMapper* card_counts_storage =
1969 create_aux_memory_mapper("Card counts table",
1970 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1971 G1CardCounts::heap_map_factor());
1972
1973 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1974 G1RegionToSpaceMapper* prev_bitmap_storage =
1975 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1976 G1RegionToSpaceMapper* next_bitmap_storage =
1977 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1978
1979 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1980 g1_barrier_set()->initialize(cardtable_storage);
1981 // Do later initialization work for concurrent refinement.
1982 _cg1r->init(card_counts_storage);
1983
1984 // 6843694 - ensure that the maximum region index can fit
1985 // in the remembered set structures.
1986 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1987 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1988
1989 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1990 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1991 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1992 "too many cards per region");
1993
1994 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1995
1996 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1997
1998 {
1999 HeapWord* start = _hrm.reserved().start();
2000 HeapWord* end = _hrm.reserved().end();
2001 size_t granularity = HeapRegion::GrainBytes;
2002
2003 _in_cset_fast_test.initialize(start, end, granularity);
2004 _humongous_reclaim_candidates.initialize(start, end, granularity);
2005 }
2006
2007 // Create the ConcurrentMark data structure and thread.
2008 // (Must do this late, so that "max_regions" is defined.)
2009 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2010 if (_cm == NULL || !_cm->completed_initialization()) {
2011 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2012 return JNI_ENOMEM;
2013 }
2014 _cmThread = _cm->cmThread();
2015
2016 // Initialize the from_card cache structure of HeapRegionRemSet.
2017 HeapRegionRemSet::init_heap(max_regions());
2018
2019 // Now expand into the initial heap size.
2020 if (!expand(init_byte_size)) {
2021 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2022 return JNI_ENOMEM;
2023 }
2024
2025 // Perform any initialization actions delegated to the policy.
2026 g1_policy()->init();
2027
2028 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2029 SATB_Q_FL_lock,
2030 G1SATBProcessCompletedThreshold,
2031 Shared_SATB_Q_lock);
2032
2033 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2034 DirtyCardQ_CBL_mon,
2035 DirtyCardQ_FL_lock,
2036 concurrent_g1_refine()->yellow_zone(),
2037 concurrent_g1_refine()->red_zone(),
2038 Shared_DirtyCardQ_lock);
2039
2040 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2041 DirtyCardQ_CBL_mon,
2042 DirtyCardQ_FL_lock,
2043 -1, // never trigger processing
2044 -1, // no limit on length
2045 Shared_DirtyCardQ_lock,
2046 &JavaThread::dirty_card_queue_set());
2047
2048 // Here we allocate the dummy HeapRegion that is required by the
2049 // G1AllocRegion class.
2050 HeapRegion* dummy_region = _hrm.get_dummy_region();
2051
2052 // We'll re-use the same region whether the alloc region will
2053 // require BOT updates or not and, if it doesn't, then a non-young
2054 // region will complain that it cannot support allocations without
2055 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2056 dummy_region->set_eden();
2057 // Make sure it's full.
2058 dummy_region->set_top(dummy_region->end());
2059 G1AllocRegion::setup(this, dummy_region);
2060
2061 _allocator->init_mutator_alloc_region();
2062
2063 // Do create of the monitoring and management support so that
2064 // values in the heap have been properly initialized.
2065 _g1mm = new G1MonitoringSupport(this);
2066
2067 G1StringDedup::initialize();
2068
2069 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2070 for (uint i = 0; i < ParallelGCThreads; i++) {
2071 new (&_preserved_objs[i]) OopAndMarkOopStack();
2072 }
2073
2074 return JNI_OK;
2075 }
2076
2077 void G1CollectedHeap::stop() {
2078 // Stop all concurrent threads. We do this to make sure these threads
2079 // do not continue to execute and access resources (e.g. gclog_or_tty)
2080 // that are destroyed during shutdown.
2081 _cg1r->stop();
2082 _cmThread->stop();
2083 if (G1StringDedup::is_enabled()) {
2084 G1StringDedup::stop();
2085 }
2086 }
2087
2088 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2089 return HeapRegion::max_region_size();
2090 }
2091
2092 void G1CollectedHeap::post_initialize() {
2093 CollectedHeap::post_initialize();
2094 ref_processing_init();
2095 }
2096
2097 void G1CollectedHeap::ref_processing_init() {
2098 // Reference processing in G1 currently works as follows:
2099 //
2100 // * There are two reference processor instances. One is
2101 // used to record and process discovered references
2102 // during concurrent marking; the other is used to
2103 // record and process references during STW pauses
2104 // (both full and incremental).
2105 // * Both ref processors need to 'span' the entire heap as
2106 // the regions in the collection set may be dotted around.
2107 //
2108 // * For the concurrent marking ref processor:
2109 // * Reference discovery is enabled at initial marking.
2110 // * Reference discovery is disabled and the discovered
2111 // references processed etc during remarking.
2112 // * Reference discovery is MT (see below).
2113 // * Reference discovery requires a barrier (see below).
2114 // * Reference processing may or may not be MT
2115 // (depending on the value of ParallelRefProcEnabled
2116 // and ParallelGCThreads).
2117 // * A full GC disables reference discovery by the CM
2118 // ref processor and abandons any entries on it's
2119 // discovered lists.
2120 //
2121 // * For the STW processor:
2122 // * Non MT discovery is enabled at the start of a full GC.
2123 // * Processing and enqueueing during a full GC is non-MT.
2124 // * During a full GC, references are processed after marking.
2125 //
2126 // * Discovery (may or may not be MT) is enabled at the start
2127 // of an incremental evacuation pause.
2128 // * References are processed near the end of a STW evacuation pause.
2129 // * For both types of GC:
2130 // * Discovery is atomic - i.e. not concurrent.
2131 // * Reference discovery will not need a barrier.
2132
2133 MemRegion mr = reserved_region();
2134
2135 // Concurrent Mark ref processor
2136 _ref_processor_cm =
2137 new ReferenceProcessor(mr, // span
2138 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2139 // mt processing
2140 ParallelGCThreads,
2141 // degree of mt processing
2142 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2143 // mt discovery
2144 MAX2(ParallelGCThreads, ConcGCThreads),
2145 // degree of mt discovery
2146 false,
2147 // Reference discovery is not atomic
2148 &_is_alive_closure_cm);
2149 // is alive closure
2150 // (for efficiency/performance)
2151
2152 // STW ref processor
2153 _ref_processor_stw =
2154 new ReferenceProcessor(mr, // span
2155 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2156 // mt processing
2157 ParallelGCThreads,
2158 // degree of mt processing
2159 (ParallelGCThreads > 1),
2160 // mt discovery
2161 ParallelGCThreads,
2162 // degree of mt discovery
2163 true,
2164 // Reference discovery is atomic
2165 &_is_alive_closure_stw);
2166 // is alive closure
2167 // (for efficiency/performance)
2168 }
2169
2170 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2171 return g1_policy();
2172 }
2173
2174 size_t G1CollectedHeap::capacity() const {
2175 return _hrm.length() * HeapRegion::GrainBytes;
2176 }
2177
2178 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2179 hr->reset_gc_time_stamp();
2180 }
2181
2182 #ifndef PRODUCT
2183
2184 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2185 private:
2186 unsigned _gc_time_stamp;
2187 bool _failures;
2188
2189 public:
2190 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2191 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2192
2193 virtual bool doHeapRegion(HeapRegion* hr) {
2194 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2195 if (_gc_time_stamp != region_gc_time_stamp) {
2196 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2197 "expected %d", HR_FORMAT_PARAMS(hr),
2198 region_gc_time_stamp, _gc_time_stamp);
2199 _failures = true;
2200 }
2201 return false;
2202 }
2203
2204 bool failures() { return _failures; }
2205 };
2206
2207 void G1CollectedHeap::check_gc_time_stamps() {
2208 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2209 heap_region_iterate(&cl);
2210 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2211 }
2212 #endif // PRODUCT
2213
2214 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2215 _cg1r->hot_card_cache()->drain(cl, worker_i);
2216 }
2217
2218 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2219 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2220 size_t n_completed_buffers = 0;
2221 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2222 n_completed_buffers++;
2223 }
2224 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2225 dcqs.clear_n_completed_buffers();
2226 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2227 }
2228
2229 // Computes the sum of the storage used by the various regions.
2230 size_t G1CollectedHeap::used() const {
2231 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2232 if (_archive_allocator != NULL) {
2233 result += _archive_allocator->used();
2234 }
2235 return result;
2236 }
2237
2238 size_t G1CollectedHeap::used_unlocked() const {
2239 return _summary_bytes_used;
2240 }
2241
2242 class SumUsedClosure: public HeapRegionClosure {
2243 size_t _used;
2244 public:
2245 SumUsedClosure() : _used(0) {}
2246 bool doHeapRegion(HeapRegion* r) {
2247 _used += r->used();
2248 return false;
2249 }
2250 size_t result() { return _used; }
2251 };
2252
2253 size_t G1CollectedHeap::recalculate_used() const {
2254 double recalculate_used_start = os::elapsedTime();
2255
2256 SumUsedClosure blk;
2257 heap_region_iterate(&blk);
2258
2259 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2260 return blk.result();
2261 }
2262
2263 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2264 switch (cause) {
2265 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2266 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2267 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2268 case GCCause::_g1_humongous_allocation: return true;
2269 case GCCause::_update_allocation_context_stats_inc: return true;
2270 case GCCause::_wb_conc_mark: return true;
2271 default: return false;
2272 }
2273 }
2274
2275 #ifndef PRODUCT
2276 void G1CollectedHeap::allocate_dummy_regions() {
2277 // Let's fill up most of the region
2278 size_t word_size = HeapRegion::GrainWords - 1024;
2279 // And as a result the region we'll allocate will be humongous.
2280 guarantee(is_humongous(word_size), "sanity");
2281
2282 // _filler_array_max_size is set to humongous object threshold
2283 // but temporarily change it to use CollectedHeap::fill_with_object().
2284 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2285
2286 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2287 // Let's use the existing mechanism for the allocation
2288 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2289 AllocationContext::system());
2290 if (dummy_obj != NULL) {
2291 MemRegion mr(dummy_obj, word_size);
2292 CollectedHeap::fill_with_object(mr);
2293 } else {
2294 // If we can't allocate once, we probably cannot allocate
2295 // again. Let's get out of the loop.
2296 break;
2297 }
2298 }
2299 }
2300 #endif // !PRODUCT
2301
2302 void G1CollectedHeap::increment_old_marking_cycles_started() {
2303 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2304 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2305 "Wrong marking cycle count (started: %d, completed: %d)",
2306 _old_marking_cycles_started, _old_marking_cycles_completed);
2307
2308 _old_marking_cycles_started++;
2309 }
2310
2311 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2312 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2313
2314 // We assume that if concurrent == true, then the caller is a
2315 // concurrent thread that was joined the Suspendible Thread
2316 // Set. If there's ever a cheap way to check this, we should add an
2317 // assert here.
2318
2319 // Given that this method is called at the end of a Full GC or of a
2320 // concurrent cycle, and those can be nested (i.e., a Full GC can
2321 // interrupt a concurrent cycle), the number of full collections
2322 // completed should be either one (in the case where there was no
2323 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2324 // behind the number of full collections started.
2325
2326 // This is the case for the inner caller, i.e. a Full GC.
2327 assert(concurrent ||
2328 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2329 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2330 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2331 "is inconsistent with _old_marking_cycles_completed = %u",
2332 _old_marking_cycles_started, _old_marking_cycles_completed);
2333
2334 // This is the case for the outer caller, i.e. the concurrent cycle.
2335 assert(!concurrent ||
2336 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2337 "for outer caller (concurrent cycle): "
2338 "_old_marking_cycles_started = %u "
2339 "is inconsistent with _old_marking_cycles_completed = %u",
2340 _old_marking_cycles_started, _old_marking_cycles_completed);
2341
2342 _old_marking_cycles_completed += 1;
2343
2344 // We need to clear the "in_progress" flag in the CM thread before
2345 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2346 // is set) so that if a waiter requests another System.gc() it doesn't
2347 // incorrectly see that a marking cycle is still in progress.
2348 if (concurrent) {
2349 _cmThread->set_idle();
2350 }
2351
2352 // This notify_all() will ensure that a thread that called
2353 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2354 // and it's waiting for a full GC to finish will be woken up. It is
2355 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2356 FullGCCount_lock->notify_all();
2357 }
2358
2359 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2360 GCIdMarkAndRestore conc_gc_id_mark;
2361 collector_state()->set_concurrent_cycle_started(true);
2362 _gc_timer_cm->register_gc_start(start_time);
2363
2364 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2365 trace_heap_before_gc(_gc_tracer_cm);
2366 _cmThread->set_gc_id(GCId::current());
2367 }
2368
2369 void G1CollectedHeap::register_concurrent_cycle_end() {
2370 if (collector_state()->concurrent_cycle_started()) {
2371 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2372 if (_cm->has_aborted()) {
2373 _gc_tracer_cm->report_concurrent_mode_failure();
2374 }
2375
2376 _gc_timer_cm->register_gc_end();
2377 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2378
2379 // Clear state variables to prepare for the next concurrent cycle.
2380 collector_state()->set_concurrent_cycle_started(false);
2381 _heap_summary_sent = false;
2382 }
2383 }
2384
2385 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2386 if (collector_state()->concurrent_cycle_started()) {
2387 // This function can be called when:
2388 // the cleanup pause is run
2389 // the concurrent cycle is aborted before the cleanup pause.
2390 // the concurrent cycle is aborted after the cleanup pause,
2391 // but before the concurrent cycle end has been registered.
2392 // Make sure that we only send the heap information once.
2393 if (!_heap_summary_sent) {
2394 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2395 trace_heap_after_gc(_gc_tracer_cm);
2396 _heap_summary_sent = true;
2397 }
2398 }
2399 }
2400
2401 void G1CollectedHeap::collect(GCCause::Cause cause) {
2402 assert_heap_not_locked();
2403
2404 uint gc_count_before;
2405 uint old_marking_count_before;
2406 uint full_gc_count_before;
2407 bool retry_gc;
2408
2409 do {
2410 retry_gc = false;
2411
2412 {
2413 MutexLocker ml(Heap_lock);
2414
2415 // Read the GC count while holding the Heap_lock
2416 gc_count_before = total_collections();
2417 full_gc_count_before = total_full_collections();
2418 old_marking_count_before = _old_marking_cycles_started;
2419 }
2420
2421 if (should_do_concurrent_full_gc(cause)) {
2422 // Schedule an initial-mark evacuation pause that will start a
2423 // concurrent cycle. We're setting word_size to 0 which means that
2424 // we are not requesting a post-GC allocation.
2425 VM_G1IncCollectionPause op(gc_count_before,
2426 0, /* word_size */
2427 true, /* should_initiate_conc_mark */
2428 g1_policy()->max_pause_time_ms(),
2429 cause);
2430 op.set_allocation_context(AllocationContext::current());
2431
2432 VMThread::execute(&op);
2433 if (!op.pause_succeeded()) {
2434 if (old_marking_count_before == _old_marking_cycles_started) {
2435 retry_gc = op.should_retry_gc();
2436 } else {
2437 // A Full GC happened while we were trying to schedule the
2438 // initial-mark GC. No point in starting a new cycle given
2439 // that the whole heap was collected anyway.
2440 }
2441
2442 if (retry_gc) {
2443 if (GC_locker::is_active_and_needs_gc()) {
2444 GC_locker::stall_until_clear();
2445 }
2446 }
2447 }
2448 } else {
2449 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2450 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2451
2452 // Schedule a standard evacuation pause. We're setting word_size
2453 // to 0 which means that we are not requesting a post-GC allocation.
2454 VM_G1IncCollectionPause op(gc_count_before,
2455 0, /* word_size */
2456 false, /* should_initiate_conc_mark */
2457 g1_policy()->max_pause_time_ms(),
2458 cause);
2459 VMThread::execute(&op);
2460 } else {
2461 // Schedule a Full GC.
2462 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2463 VMThread::execute(&op);
2464 }
2465 }
2466 } while (retry_gc);
2467 }
2468
2469 bool G1CollectedHeap::is_in(const void* p) const {
2470 if (_hrm.reserved().contains(p)) {
2471 // Given that we know that p is in the reserved space,
2472 // heap_region_containing() should successfully
2473 // return the containing region.
2474 HeapRegion* hr = heap_region_containing(p);
2475 return hr->is_in(p);
2476 } else {
2477 return false;
2478 }
2479 }
2480
2481 #ifdef ASSERT
2482 bool G1CollectedHeap::is_in_exact(const void* p) const {
2483 bool contains = reserved_region().contains(p);
2484 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2485 if (contains && available) {
2486 return true;
2487 } else {
2488 return false;
2489 }
2490 }
2491 #endif
2492
2493 bool G1CollectedHeap::obj_in_cs(oop obj) {
2494 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2495 return r != NULL && r->in_collection_set();
2496 }
2497
2498 // Iteration functions.
2499
2500 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2501
2502 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2503 ExtendedOopClosure* _cl;
2504 public:
2505 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2506 bool doHeapRegion(HeapRegion* r) {
2507 if (!r->is_continues_humongous()) {
2508 r->oop_iterate(_cl);
2509 }
2510 return false;
2511 }
2512 };
2513
2514 // Iterates an ObjectClosure over all objects within a HeapRegion.
2515
2516 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2517 ObjectClosure* _cl;
2518 public:
2519 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2520 bool doHeapRegion(HeapRegion* r) {
2521 if (!r->is_continues_humongous()) {
2522 r->object_iterate(_cl);
2523 }
2524 return false;
2525 }
2526 };
2527
2528 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2529 IterateObjectClosureRegionClosure blk(cl);
2530 heap_region_iterate(&blk);
2531 }
2532
2533 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2534 _hrm.iterate(cl);
2535 }
2536
2537 void
2538 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2539 uint worker_id,
2540 HeapRegionClaimer *hrclaimer,
2541 bool concurrent) const {
2542 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2543 }
2544
2545 // Clear the cached CSet starting regions and (more importantly)
2546 // the time stamps. Called when we reset the GC time stamp.
2547 void G1CollectedHeap::clear_cset_start_regions() {
2548 assert(_worker_cset_start_region != NULL, "sanity");
2549 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2550
2551 for (uint i = 0; i < ParallelGCThreads; i++) {
2552 _worker_cset_start_region[i] = NULL;
2553 _worker_cset_start_region_time_stamp[i] = 0;
2554 }
2555 }
2556
2557 // Given the id of a worker, obtain or calculate a suitable
2558 // starting region for iterating over the current collection set.
2559 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2560 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2561
2562 HeapRegion* result = NULL;
2563 unsigned gc_time_stamp = get_gc_time_stamp();
2564
2565 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2566 // Cached starting region for current worker was set
2567 // during the current pause - so it's valid.
2568 // Note: the cached starting heap region may be NULL
2569 // (when the collection set is empty).
2570 result = _worker_cset_start_region[worker_i];
2571 assert(result == NULL || result->in_collection_set(), "sanity");
2572 return result;
2573 }
2574
2575 // The cached entry was not valid so let's calculate
2576 // a suitable starting heap region for this worker.
2577
2578 // We want the parallel threads to start their collection
2579 // set iteration at different collection set regions to
2580 // avoid contention.
2581 // If we have:
2582 // n collection set regions
2583 // p threads
2584 // Then thread t will start at region floor ((t * n) / p)
2585
2586 result = g1_policy()->collection_set();
2587 uint cs_size = g1_policy()->cset_region_length();
2588 uint active_workers = workers()->active_workers();
2589
2590 uint end_ind = (cs_size * worker_i) / active_workers;
2591 uint start_ind = 0;
2592
2593 if (worker_i > 0 &&
2594 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2595 // Previous workers starting region is valid
2596 // so let's iterate from there
2597 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2598 result = _worker_cset_start_region[worker_i - 1];
2599 }
2600
2601 for (uint i = start_ind; i < end_ind; i++) {
2602 result = result->next_in_collection_set();
2603 }
2604
2605 // Note: the calculated starting heap region may be NULL
2606 // (when the collection set is empty).
2607 assert(result == NULL || result->in_collection_set(), "sanity");
2608 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2609 "should be updated only once per pause");
2610 _worker_cset_start_region[worker_i] = result;
2611 OrderAccess::storestore();
2612 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2613 return result;
2614 }
2615
2616 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2617 HeapRegion* r = g1_policy()->collection_set();
2618 while (r != NULL) {
2619 HeapRegion* next = r->next_in_collection_set();
2620 if (cl->doHeapRegion(r)) {
2621 cl->incomplete();
2622 return;
2623 }
2624 r = next;
2625 }
2626 }
2627
2628 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2629 HeapRegionClosure *cl) {
2630 if (r == NULL) {
2631 // The CSet is empty so there's nothing to do.
2632 return;
2633 }
2634
2635 assert(r->in_collection_set(),
2636 "Start region must be a member of the collection set.");
2637 HeapRegion* cur = r;
2638 while (cur != NULL) {
2639 HeapRegion* next = cur->next_in_collection_set();
2640 if (cl->doHeapRegion(cur) && false) {
2641 cl->incomplete();
2642 return;
2643 }
2644 cur = next;
2645 }
2646 cur = g1_policy()->collection_set();
2647 while (cur != r) {
2648 HeapRegion* next = cur->next_in_collection_set();
2649 if (cl->doHeapRegion(cur) && false) {
2650 cl->incomplete();
2651 return;
2652 }
2653 cur = next;
2654 }
2655 }
2656
2657 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2658 HeapRegion* result = _hrm.next_region_in_heap(from);
2659 while (result != NULL && result->is_pinned()) {
2660 result = _hrm.next_region_in_heap(result);
2661 }
2662 return result;
2663 }
2664
2665 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2666 HeapRegion* hr = heap_region_containing(addr);
2667 return hr->block_start(addr);
2668 }
2669
2670 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2671 HeapRegion* hr = heap_region_containing(addr);
2672 return hr->block_size(addr);
2673 }
2674
2675 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2676 HeapRegion* hr = heap_region_containing(addr);
2677 return hr->block_is_obj(addr);
2678 }
2679
2680 bool G1CollectedHeap::supports_tlab_allocation() const {
2681 return true;
2682 }
2683
2684 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2685 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2686 }
2687
2688 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2689 return young_list()->eden_used_bytes();
2690 }
2691
2692 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2693 // must be equal to the humongous object limit.
2694 size_t G1CollectedHeap::max_tlab_size() const {
2695 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2696 }
2697
2698 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2699 AllocationContext_t context = AllocationContext::current();
2700 return _allocator->unsafe_max_tlab_alloc(context);
2701 }
2702
2703 size_t G1CollectedHeap::max_capacity() const {
2704 return _hrm.reserved().byte_size();
2705 }
2706
2707 jlong G1CollectedHeap::millis_since_last_gc() {
2708 // assert(false, "NYI");
2709 return 0;
2710 }
2711
2712 void G1CollectedHeap::prepare_for_verify() {
2713 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2714 ensure_parsability(false);
2715 }
2716 g1_rem_set()->prepare_for_verify();
2717 }
2718
2719 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2720 VerifyOption vo) {
2721 switch (vo) {
2722 case VerifyOption_G1UsePrevMarking:
2723 return hr->obj_allocated_since_prev_marking(obj);
2724 case VerifyOption_G1UseNextMarking:
2725 return hr->obj_allocated_since_next_marking(obj);
2726 case VerifyOption_G1UseMarkWord:
2727 return false;
2728 default:
2729 ShouldNotReachHere();
2730 }
2731 return false; // keep some compilers happy
2732 }
2733
2734 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2735 switch (vo) {
2736 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2737 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2738 case VerifyOption_G1UseMarkWord: return NULL;
2739 default: ShouldNotReachHere();
2740 }
2741 return NULL; // keep some compilers happy
2742 }
2743
2744 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2745 switch (vo) {
2746 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2747 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2748 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2749 default: ShouldNotReachHere();
2750 }
2751 return false; // keep some compilers happy
2752 }
2753
2754 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2755 switch (vo) {
2756 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2757 case VerifyOption_G1UseNextMarking: return "NTAMS";
2758 case VerifyOption_G1UseMarkWord: return "NONE";
2759 default: ShouldNotReachHere();
2760 }
2761 return NULL; // keep some compilers happy
2762 }
2763
2764 class VerifyRootsClosure: public OopClosure {
2765 private:
2766 G1CollectedHeap* _g1h;
2767 VerifyOption _vo;
2768 bool _failures;
2769 public:
2770 // _vo == UsePrevMarking -> use "prev" marking information,
2771 // _vo == UseNextMarking -> use "next" marking information,
2772 // _vo == UseMarkWord -> use mark word from object header.
2773 VerifyRootsClosure(VerifyOption vo) :
2774 _g1h(G1CollectedHeap::heap()),
2775 _vo(vo),
2776 _failures(false) { }
2777
2778 bool failures() { return _failures; }
2779
2780 template <class T> void do_oop_nv(T* p) {
2781 T heap_oop = oopDesc::load_heap_oop(p);
2782 if (!oopDesc::is_null(heap_oop)) {
2783 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2784 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2785 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2786 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2787 if (_vo == VerifyOption_G1UseMarkWord) {
2788 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2789 }
2790 obj->print_on(gclog_or_tty);
2791 _failures = true;
2792 }
2793 }
2794 }
2795
2796 void do_oop(oop* p) { do_oop_nv(p); }
2797 void do_oop(narrowOop* p) { do_oop_nv(p); }
2798 };
2799
2800 class G1VerifyCodeRootOopClosure: public OopClosure {
2801 G1CollectedHeap* _g1h;
2802 OopClosure* _root_cl;
2803 nmethod* _nm;
2804 VerifyOption _vo;
2805 bool _failures;
2806
2807 template <class T> void do_oop_work(T* p) {
2808 // First verify that this root is live
2809 _root_cl->do_oop(p);
2810
2811 if (!G1VerifyHeapRegionCodeRoots) {
2812 // We're not verifying the code roots attached to heap region.
2813 return;
2814 }
2815
2816 // Don't check the code roots during marking verification in a full GC
2817 if (_vo == VerifyOption_G1UseMarkWord) {
2818 return;
2819 }
2820
2821 // Now verify that the current nmethod (which contains p) is
2822 // in the code root list of the heap region containing the
2823 // object referenced by p.
2824
2825 T heap_oop = oopDesc::load_heap_oop(p);
2826 if (!oopDesc::is_null(heap_oop)) {
2827 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2828
2829 // Now fetch the region containing the object
2830 HeapRegion* hr = _g1h->heap_region_containing(obj);
2831 HeapRegionRemSet* hrrs = hr->rem_set();
2832 // Verify that the strong code root list for this region
2833 // contains the nmethod
2834 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2835 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2836 "from nmethod " PTR_FORMAT " not in strong "
2837 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2838 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2839 _failures = true;
2840 }
2841 }
2842 }
2843
2844 public:
2845 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2846 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2847
2848 void do_oop(oop* p) { do_oop_work(p); }
2849 void do_oop(narrowOop* p) { do_oop_work(p); }
2850
2851 void set_nmethod(nmethod* nm) { _nm = nm; }
2852 bool failures() { return _failures; }
2853 };
2854
2855 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2856 G1VerifyCodeRootOopClosure* _oop_cl;
2857
2858 public:
2859 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2860 _oop_cl(oop_cl) {}
2861
2862 void do_code_blob(CodeBlob* cb) {
2863 nmethod* nm = cb->as_nmethod_or_null();
2864 if (nm != NULL) {
2865 _oop_cl->set_nmethod(nm);
2866 nm->oops_do(_oop_cl);
2867 }
2868 }
2869 };
2870
2871 class YoungRefCounterClosure : public OopClosure {
2872 G1CollectedHeap* _g1h;
2873 int _count;
2874 public:
2875 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2876 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2877 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2878
2879 int count() { return _count; }
2880 void reset_count() { _count = 0; };
2881 };
2882
2883 class VerifyKlassClosure: public KlassClosure {
2884 YoungRefCounterClosure _young_ref_counter_closure;
2885 OopClosure *_oop_closure;
2886 public:
2887 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2888 void do_klass(Klass* k) {
2889 k->oops_do(_oop_closure);
2890
2891 _young_ref_counter_closure.reset_count();
2892 k->oops_do(&_young_ref_counter_closure);
2893 if (_young_ref_counter_closure.count() > 0) {
2894 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2895 }
2896 }
2897 };
2898
2899 class VerifyLivenessOopClosure: public OopClosure {
2900 G1CollectedHeap* _g1h;
2901 VerifyOption _vo;
2902 public:
2903 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2904 _g1h(g1h), _vo(vo)
2905 { }
2906 void do_oop(narrowOop *p) { do_oop_work(p); }
2907 void do_oop( oop *p) { do_oop_work(p); }
2908
2909 template <class T> void do_oop_work(T *p) {
2910 oop obj = oopDesc::load_decode_heap_oop(p);
2911 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2912 "Dead object referenced by a not dead object");
2913 }
2914 };
2915
2916 class VerifyObjsInRegionClosure: public ObjectClosure {
2917 private:
2918 G1CollectedHeap* _g1h;
2919 size_t _live_bytes;
2920 HeapRegion *_hr;
2921 VerifyOption _vo;
2922 public:
2923 // _vo == UsePrevMarking -> use "prev" marking information,
2924 // _vo == UseNextMarking -> use "next" marking information,
2925 // _vo == UseMarkWord -> use mark word from object header.
2926 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2927 : _live_bytes(0), _hr(hr), _vo(vo) {
2928 _g1h = G1CollectedHeap::heap();
2929 }
2930 void do_object(oop o) {
2931 VerifyLivenessOopClosure isLive(_g1h, _vo);
2932 assert(o != NULL, "Huh?");
2933 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2934 // If the object is alive according to the mark word,
2935 // then verify that the marking information agrees.
2936 // Note we can't verify the contra-positive of the
2937 // above: if the object is dead (according to the mark
2938 // word), it may not be marked, or may have been marked
2939 // but has since became dead, or may have been allocated
2940 // since the last marking.
2941 if (_vo == VerifyOption_G1UseMarkWord) {
2942 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2943 }
2944
2945 o->oop_iterate_no_header(&isLive);
2946 if (!_hr->obj_allocated_since_prev_marking(o)) {
2947 size_t obj_size = o->size(); // Make sure we don't overflow
2948 _live_bytes += (obj_size * HeapWordSize);
2949 }
2950 }
2951 }
2952 size_t live_bytes() { return _live_bytes; }
2953 };
2954
2955 class VerifyArchiveOopClosure: public OopClosure {
2956 public:
2957 VerifyArchiveOopClosure(HeapRegion *hr) { }
2958 void do_oop(narrowOop *p) { do_oop_work(p); }
2959 void do_oop( oop *p) { do_oop_work(p); }
2960
2961 template <class T> void do_oop_work(T *p) {
2962 oop obj = oopDesc::load_decode_heap_oop(p);
2963 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2964 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2965 p2i(p), p2i(obj));
2966 }
2967 };
2968
2969 class VerifyArchiveRegionClosure: public ObjectClosure {
2970 public:
2971 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2972 // Verify that all object pointers are to archive regions.
2973 void do_object(oop o) {
2974 VerifyArchiveOopClosure checkOop(NULL);
2975 assert(o != NULL, "Should not be here for NULL oops");
2976 o->oop_iterate_no_header(&checkOop);
2977 }
2978 };
2979
2980 class VerifyRegionClosure: public HeapRegionClosure {
2981 private:
2982 bool _par;
2983 VerifyOption _vo;
2984 bool _failures;
2985 public:
2986 // _vo == UsePrevMarking -> use "prev" marking information,
2987 // _vo == UseNextMarking -> use "next" marking information,
2988 // _vo == UseMarkWord -> use mark word from object header.
2989 VerifyRegionClosure(bool par, VerifyOption vo)
2990 : _par(par),
2991 _vo(vo),
2992 _failures(false) {}
2993
2994 bool failures() {
2995 return _failures;
2996 }
2997
2998 bool doHeapRegion(HeapRegion* r) {
2999 // For archive regions, verify there are no heap pointers to
3000 // non-pinned regions. For all others, verify liveness info.
3001 if (r->is_archive()) {
3002 VerifyArchiveRegionClosure verify_oop_pointers(r);
3003 r->object_iterate(&verify_oop_pointers);
3004 return true;
3005 }
3006 if (!r->is_continues_humongous()) {
3007 bool failures = false;
3008 r->verify(_vo, &failures);
3009 if (failures) {
3010 _failures = true;
3011 } else if (!r->is_starts_humongous()) {
3012 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3013 r->object_iterate(¬_dead_yet_cl);
3014 if (_vo != VerifyOption_G1UseNextMarking) {
3015 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3016 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3017 "max_live_bytes " SIZE_FORMAT " "
3018 "< calculated " SIZE_FORMAT,
3019 p2i(r->bottom()), p2i(r->end()),
3020 r->max_live_bytes(),
3021 not_dead_yet_cl.live_bytes());
3022 _failures = true;
3023 }
3024 } else {
3025 // When vo == UseNextMarking we cannot currently do a sanity
3026 // check on the live bytes as the calculation has not been
3027 // finalized yet.
3028 }
3029 }
3030 }
3031 return false; // stop the region iteration if we hit a failure
3032 }
3033 };
3034
3035 // This is the task used for parallel verification of the heap regions
3036
3037 class G1ParVerifyTask: public AbstractGangTask {
3038 private:
3039 G1CollectedHeap* _g1h;
3040 VerifyOption _vo;
3041 bool _failures;
3042 HeapRegionClaimer _hrclaimer;
3043
3044 public:
3045 // _vo == UsePrevMarking -> use "prev" marking information,
3046 // _vo == UseNextMarking -> use "next" marking information,
3047 // _vo == UseMarkWord -> use mark word from object header.
3048 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3049 AbstractGangTask("Parallel verify task"),
3050 _g1h(g1h),
3051 _vo(vo),
3052 _failures(false),
3053 _hrclaimer(g1h->workers()->active_workers()) {}
3054
3055 bool failures() {
3056 return _failures;
3057 }
3058
3059 void work(uint worker_id) {
3060 HandleMark hm;
3061 VerifyRegionClosure blk(true, _vo);
3062 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3063 if (blk.failures()) {
3064 _failures = true;
3065 }
3066 }
3067 };
3068
3069 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3070 if (SafepointSynchronize::is_at_safepoint()) {
3071 assert(Thread::current()->is_VM_thread(),
3072 "Expected to be executed serially by the VM thread at this point");
3073
3074 if (!silent) { gclog_or_tty->print("Roots "); }
3075 VerifyRootsClosure rootsCl(vo);
3076 VerifyKlassClosure klassCl(this, &rootsCl);
3077 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3078
3079 // We apply the relevant closures to all the oops in the
3080 // system dictionary, class loader data graph, the string table
3081 // and the nmethods in the code cache.
3082 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3083 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3084
3085 {
3086 G1RootProcessor root_processor(this, 1);
3087 root_processor.process_all_roots(&rootsCl,
3088 &cldCl,
3089 &blobsCl);
3090 }
3091
3092 bool failures = rootsCl.failures() || codeRootsCl.failures();
3093
3094 if (vo != VerifyOption_G1UseMarkWord) {
3095 // If we're verifying during a full GC then the region sets
3096 // will have been torn down at the start of the GC. Therefore
3097 // verifying the region sets will fail. So we only verify
3098 // the region sets when not in a full GC.
3099 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3100 verify_region_sets();
3101 }
3102
3103 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3104 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3105
3106 G1ParVerifyTask task(this, vo);
3107 workers()->run_task(&task);
3108 if (task.failures()) {
3109 failures = true;
3110 }
3111
3112 } else {
3113 VerifyRegionClosure blk(false, vo);
3114 heap_region_iterate(&blk);
3115 if (blk.failures()) {
3116 failures = true;
3117 }
3118 }
3119
3120 if (G1StringDedup::is_enabled()) {
3121 if (!silent) gclog_or_tty->print("StrDedup ");
3122 G1StringDedup::verify();
3123 }
3124
3125 if (failures) {
3126 gclog_or_tty->print_cr("Heap:");
3127 // It helps to have the per-region information in the output to
3128 // help us track down what went wrong. This is why we call
3129 // print_extended_on() instead of print_on().
3130 print_extended_on(gclog_or_tty);
3131 gclog_or_tty->cr();
3132 gclog_or_tty->flush();
3133 }
3134 guarantee(!failures, "there should not have been any failures");
3135 } else {
3136 if (!silent) {
3137 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3138 if (G1StringDedup::is_enabled()) {
3139 gclog_or_tty->print(", StrDedup");
3140 }
3141 gclog_or_tty->print(") ");
3142 }
3143 }
3144 }
3145
3146 void G1CollectedHeap::verify(bool silent) {
3147 verify(silent, VerifyOption_G1UsePrevMarking);
3148 }
3149
3150 double G1CollectedHeap::verify(bool guard, const char* msg) {
3151 double verify_time_ms = 0.0;
3152
3153 if (guard && total_collections() >= VerifyGCStartAt) {
3154 double verify_start = os::elapsedTime();
3155 HandleMark hm; // Discard invalid handles created during verification
3156 prepare_for_verify();
3157 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3158 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3159 }
3160
3161 return verify_time_ms;
3162 }
3163
3164 void G1CollectedHeap::verify_before_gc() {
3165 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3166 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3167 }
3168
3169 void G1CollectedHeap::verify_after_gc() {
3170 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3171 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3172 }
3173
3174 class PrintRegionClosure: public HeapRegionClosure {
3175 outputStream* _st;
3176 public:
3177 PrintRegionClosure(outputStream* st) : _st(st) {}
3178 bool doHeapRegion(HeapRegion* r) {
3179 r->print_on(_st);
3180 return false;
3181 }
3182 };
3183
3184 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3185 const HeapRegion* hr,
3186 const VerifyOption vo) const {
3187 switch (vo) {
3188 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3189 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3190 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3191 default: ShouldNotReachHere();
3192 }
3193 return false; // keep some compilers happy
3194 }
3195
3196 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3197 const VerifyOption vo) const {
3198 switch (vo) {
3199 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3200 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3201 case VerifyOption_G1UseMarkWord: {
3202 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3203 return !obj->is_gc_marked() && !hr->is_archive();
3204 }
3205 default: ShouldNotReachHere();
3206 }
3207 return false; // keep some compilers happy
3208 }
3209
3210 void G1CollectedHeap::print_on(outputStream* st) const {
3211 st->print(" %-20s", "garbage-first heap");
3212 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3213 capacity()/K, used_unlocked()/K);
3214 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3215 p2i(_hrm.reserved().start()),
3216 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3217 p2i(_hrm.reserved().end()));
3218 st->cr();
3219 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3220 uint young_regions = _young_list->length();
3221 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3222 (size_t) young_regions * HeapRegion::GrainBytes / K);
3223 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3224 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3225 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3226 st->cr();
3227 MetaspaceAux::print_on(st);
3228 }
3229
3230 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3231 print_on(st);
3232
3233 // Print the per-region information.
3234 st->cr();
3235 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3236 "HS=humongous(starts), HC=humongous(continues), "
3237 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3238 "PTAMS=previous top-at-mark-start, "
3239 "NTAMS=next top-at-mark-start)");
3240 PrintRegionClosure blk(st);
3241 heap_region_iterate(&blk);
3242 }
3243
3244 void G1CollectedHeap::print_on_error(outputStream* st) const {
3245 this->CollectedHeap::print_on_error(st);
3246
3247 if (_cm != NULL) {
3248 st->cr();
3249 _cm->print_on_error(st);
3250 }
3251 }
3252
3253 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3254 workers()->print_worker_threads_on(st);
3255 _cmThread->print_on(st);
3256 st->cr();
3257 _cm->print_worker_threads_on(st);
3258 _cg1r->print_worker_threads_on(st);
3259 if (G1StringDedup::is_enabled()) {
3260 G1StringDedup::print_worker_threads_on(st);
3261 }
3262 }
3263
3264 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3265 workers()->threads_do(tc);
3266 tc->do_thread(_cmThread);
3267 _cg1r->threads_do(tc);
3268 if (G1StringDedup::is_enabled()) {
3269 G1StringDedup::threads_do(tc);
3270 }
3271 }
3272
3273 void G1CollectedHeap::print_tracing_info() const {
3274 // We'll overload this to mean "trace GC pause statistics."
3275 if (TraceYoungGenTime || TraceOldGenTime) {
3276 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3277 // to that.
3278 g1_policy()->print_tracing_info();
3279 }
3280 if (G1SummarizeRSetStats) {
3281 g1_rem_set()->print_summary_info();
3282 }
3283 if (G1SummarizeConcMark) {
3284 concurrent_mark()->print_summary_info();
3285 }
3286 g1_policy()->print_yg_surv_rate_info();
3287 }
3288
3289 #ifndef PRODUCT
3290 // Helpful for debugging RSet issues.
3291
3292 class PrintRSetsClosure : public HeapRegionClosure {
3293 private:
3294 const char* _msg;
3295 size_t _occupied_sum;
3296
3297 public:
3298 bool doHeapRegion(HeapRegion* r) {
3299 HeapRegionRemSet* hrrs = r->rem_set();
3300 size_t occupied = hrrs->occupied();
3301 _occupied_sum += occupied;
3302
3303 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3304 HR_FORMAT_PARAMS(r));
3305 if (occupied == 0) {
3306 gclog_or_tty->print_cr(" RSet is empty");
3307 } else {
3308 hrrs->print();
3309 }
3310 gclog_or_tty->print_cr("----------");
3311 return false;
3312 }
3313
3314 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3315 gclog_or_tty->cr();
3316 gclog_or_tty->print_cr("========================================");
3317 gclog_or_tty->print_cr("%s", msg);
3318 gclog_or_tty->cr();
3319 }
3320
3321 ~PrintRSetsClosure() {
3322 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3323 gclog_or_tty->print_cr("========================================");
3324 gclog_or_tty->cr();
3325 }
3326 };
3327
3328 void G1CollectedHeap::print_cset_rsets() {
3329 PrintRSetsClosure cl("Printing CSet RSets");
3330 collection_set_iterate(&cl);
3331 }
3332
3333 void G1CollectedHeap::print_all_rsets() {
3334 PrintRSetsClosure cl("Printing All RSets");;
3335 heap_region_iterate(&cl);
3336 }
3337 #endif // PRODUCT
3338
3339 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3340 YoungList* young_list = heap()->young_list();
3341
3342 size_t eden_used_bytes = young_list->eden_used_bytes();
3343 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3344
3345 size_t eden_capacity_bytes =
3346 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3347
3348 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3349 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3350 }
3351
3352 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3353 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3354 stats->unused(), stats->used(), stats->region_end_waste(),
3355 stats->regions_filled(), stats->direct_allocated(),
3356 stats->failure_used(), stats->failure_waste());
3357 }
3358
3359 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3360 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3361 gc_tracer->report_gc_heap_summary(when, heap_summary);
3362
3363 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3364 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3365 }
3366
3367
3368 G1CollectedHeap* G1CollectedHeap::heap() {
3369 CollectedHeap* heap = Universe::heap();
3370 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3371 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3372 return (G1CollectedHeap*)heap;
3373 }
3374
3375 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3376 // always_do_update_barrier = false;
3377 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3378 // Fill TLAB's and such
3379 accumulate_statistics_all_tlabs();
3380 ensure_parsability(true);
3381
3382 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3383 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3384 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3385 }
3386 }
3387
3388 void G1CollectedHeap::gc_epilogue(bool full) {
3389
3390 if (G1SummarizeRSetStats &&
3391 (G1SummarizeRSetStatsPeriod > 0) &&
3392 // we are at the end of the GC. Total collections has already been increased.
3393 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3394 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3395 }
3396
3397 // FIXME: what is this about?
3398 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3399 // is set.
3400 #if defined(COMPILER2) || INCLUDE_JVMCI
3401 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3402 #endif
3403 // always_do_update_barrier = true;
3404
3405 resize_all_tlabs();
3406 allocation_context_stats().update(full);
3407
3408 // We have just completed a GC. Update the soft reference
3409 // policy with the new heap occupancy
3410 Universe::update_heap_info_at_gc();
3411 }
3412
3413 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3414 uint gc_count_before,
3415 bool* succeeded,
3416 GCCause::Cause gc_cause) {
3417 assert_heap_not_locked_and_not_at_safepoint();
3418 g1_policy()->record_stop_world_start();
3419 VM_G1IncCollectionPause op(gc_count_before,
3420 word_size,
3421 false, /* should_initiate_conc_mark */
3422 g1_policy()->max_pause_time_ms(),
3423 gc_cause);
3424
3425 op.set_allocation_context(AllocationContext::current());
3426 VMThread::execute(&op);
3427
3428 HeapWord* result = op.result();
3429 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3430 assert(result == NULL || ret_succeeded,
3431 "the result should be NULL if the VM did not succeed");
3432 *succeeded = ret_succeeded;
3433
3434 assert_heap_not_locked();
3435 return result;
3436 }
3437
3438 void
3439 G1CollectedHeap::doConcurrentMark() {
3440 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3441 if (!_cmThread->in_progress()) {
3442 _cmThread->set_started();
3443 CGC_lock->notify();
3444 }
3445 }
3446
3447 size_t G1CollectedHeap::pending_card_num() {
3448 size_t extra_cards = 0;
3449 JavaThread *curr = Threads::first();
3450 while (curr != NULL) {
3451 DirtyCardQueue& dcq = curr->dirty_card_queue();
3452 extra_cards += dcq.size();
3453 curr = curr->next();
3454 }
3455 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3456 size_t buffer_size = dcqs.buffer_size();
3457 size_t buffer_num = dcqs.completed_buffers_num();
3458
3459 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3460 // in bytes - not the number of 'entries'. We need to convert
3461 // into a number of cards.
3462 return (buffer_size * buffer_num + extra_cards) / oopSize;
3463 }
3464
3465 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3466 private:
3467 size_t _total_humongous;
3468 size_t _candidate_humongous;
3469
3470 DirtyCardQueue _dcq;
3471
3472 // We don't nominate objects with many remembered set entries, on
3473 // the assumption that such objects are likely still live.
3474 bool is_remset_small(HeapRegion* region) const {
3475 HeapRegionRemSet* const rset = region->rem_set();
3476 return G1EagerReclaimHumongousObjectsWithStaleRefs
3477 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3478 : rset->is_empty();
3479 }
3480
3481 bool is_typeArray_region(HeapRegion* region) const {
3482 return oop(region->bottom())->is_typeArray();
3483 }
3484
3485 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3486 assert(region->is_starts_humongous(), "Must start a humongous object");
3487
3488 // Candidate selection must satisfy the following constraints
3489 // while concurrent marking is in progress:
3490 //
3491 // * In order to maintain SATB invariants, an object must not be
3492 // reclaimed if it was allocated before the start of marking and
3493 // has not had its references scanned. Such an object must have
3494 // its references (including type metadata) scanned to ensure no
3495 // live objects are missed by the marking process. Objects
3496 // allocated after the start of concurrent marking don't need to
3497 // be scanned.
3498 //
3499 // * An object must not be reclaimed if it is on the concurrent
3500 // mark stack. Objects allocated after the start of concurrent
3501 // marking are never pushed on the mark stack.
3502 //
3503 // Nominating only objects allocated after the start of concurrent
3504 // marking is sufficient to meet both constraints. This may miss
3505 // some objects that satisfy the constraints, but the marking data
3506 // structures don't support efficiently performing the needed
3507 // additional tests or scrubbing of the mark stack.
3508 //
3509 // However, we presently only nominate is_typeArray() objects.
3510 // A humongous object containing references induces remembered
3511 // set entries on other regions. In order to reclaim such an
3512 // object, those remembered sets would need to be cleaned up.
3513 //
3514 // We also treat is_typeArray() objects specially, allowing them
3515 // to be reclaimed even if allocated before the start of
3516 // concurrent mark. For this we rely on mark stack insertion to
3517 // exclude is_typeArray() objects, preventing reclaiming an object
3518 // that is in the mark stack. We also rely on the metadata for
3519 // such objects to be built-in and so ensured to be kept live.
3520 // Frequent allocation and drop of large binary blobs is an
3521 // important use case for eager reclaim, and this special handling
3522 // may reduce needed headroom.
3523
3524 return is_typeArray_region(region) && is_remset_small(region);
3525 }
3526
3527 public:
3528 RegisterHumongousWithInCSetFastTestClosure()
3529 : _total_humongous(0),
3530 _candidate_humongous(0),
3531 _dcq(&JavaThread::dirty_card_queue_set()) {
3532 }
3533
3534 virtual bool doHeapRegion(HeapRegion* r) {
3535 if (!r->is_starts_humongous()) {
3536 return false;
3537 }
3538 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3539
3540 bool is_candidate = humongous_region_is_candidate(g1h, r);
3541 uint rindex = r->hrm_index();
3542 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3543 if (is_candidate) {
3544 _candidate_humongous++;
3545 g1h->register_humongous_region_with_cset(rindex);
3546 // Is_candidate already filters out humongous object with large remembered sets.
3547 // If we have a humongous object with a few remembered sets, we simply flush these
3548 // remembered set entries into the DCQS. That will result in automatic
3549 // re-evaluation of their remembered set entries during the following evacuation
3550 // phase.
3551 if (!r->rem_set()->is_empty()) {
3552 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3553 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3554 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3555 HeapRegionRemSetIterator hrrs(r->rem_set());
3556 size_t card_index;
3557 while (hrrs.has_next(card_index)) {
3558 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3559 // The remembered set might contain references to already freed
3560 // regions. Filter out such entries to avoid failing card table
3561 // verification.
3562 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3563 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3564 *card_ptr = CardTableModRefBS::dirty_card_val();
3565 _dcq.enqueue(card_ptr);
3566 }
3567 }
3568 }
3569 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3570 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3571 hrrs.n_yielded(), r->rem_set()->occupied());
3572 r->rem_set()->clear_locked();
3573 }
3574 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3575 }
3576 _total_humongous++;
3577
3578 return false;
3579 }
3580
3581 size_t total_humongous() const { return _total_humongous; }
3582 size_t candidate_humongous() const { return _candidate_humongous; }
3583
3584 void flush_rem_set_entries() { _dcq.flush(); }
3585 };
3586
3587 void G1CollectedHeap::register_humongous_regions_with_cset() {
3588 if (!G1EagerReclaimHumongousObjects) {
3589 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3590 return;
3591 }
3592 double time = os::elapsed_counter();
3593
3594 // Collect reclaim candidate information and register candidates with cset.
3595 RegisterHumongousWithInCSetFastTestClosure cl;
3596 heap_region_iterate(&cl);
3597
3598 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3599 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3600 cl.total_humongous(),
3601 cl.candidate_humongous());
3602 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3603
3604 // Finally flush all remembered set entries to re-check into the global DCQS.
3605 cl.flush_rem_set_entries();
3606 }
3607
3608 #ifdef ASSERT
3609 class VerifyCSetClosure: public HeapRegionClosure {
3610 public:
3611 bool doHeapRegion(HeapRegion* hr) {
3612 // Here we check that the CSet region's RSet is ready for parallel
3613 // iteration. The fields that we'll verify are only manipulated
3614 // when the region is part of a CSet and is collected. Afterwards,
3615 // we reset these fields when we clear the region's RSet (when the
3616 // region is freed) so they are ready when the region is
3617 // re-allocated. The only exception to this is if there's an
3618 // evacuation failure and instead of freeing the region we leave
3619 // it in the heap. In that case, we reset these fields during
3620 // evacuation failure handling.
3621 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3622
3623 // Here's a good place to add any other checks we'd like to
3624 // perform on CSet regions.
3625 return false;
3626 }
3627 };
3628 #endif // ASSERT
3629
3630 uint G1CollectedHeap::num_task_queues() const {
3631 return _task_queues->size();
3632 }
3633
3634 #if TASKQUEUE_STATS
3635 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3636 st->print_raw_cr("GC Task Stats");
3637 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3638 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3639 }
3640
3641 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3642 print_taskqueue_stats_hdr(st);
3643
3644 TaskQueueStats totals;
3645 const uint n = num_task_queues();
3646 for (uint i = 0; i < n; ++i) {
3647 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3648 totals += task_queue(i)->stats;
3649 }
3650 st->print_raw("tot "); totals.print(st); st->cr();
3651
3652 DEBUG_ONLY(totals.verify());
3653 }
3654
3655 void G1CollectedHeap::reset_taskqueue_stats() {
3656 const uint n = num_task_queues();
3657 for (uint i = 0; i < n; ++i) {
3658 task_queue(i)->stats.reset();
3659 }
3660 }
3661 #endif // TASKQUEUE_STATS
3662
3663 void G1CollectedHeap::log_gc_header() {
3664 if (!G1Log::fine()) {
3665 return;
3666 }
3667
3668 gclog_or_tty->gclog_stamp();
3669
3670 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3671 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3672 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3673
3674 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3675 }
3676
3677 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3678 if (!G1Log::fine()) {
3679 return;
3680 }
3681
3682 if (G1Log::finer()) {
3683 if (evacuation_failed()) {
3684 gclog_or_tty->print(" (to-space exhausted)");
3685 }
3686 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3687 g1_policy()->print_phases(pause_time_sec);
3688 g1_policy()->print_detailed_heap_transition();
3689 } else {
3690 if (evacuation_failed()) {
3691 gclog_or_tty->print("--");
3692 }
3693 g1_policy()->print_heap_transition();
3694 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3695 }
3696 gclog_or_tty->flush();
3697 }
3698
3699 void G1CollectedHeap::wait_for_root_region_scanning() {
3700 double scan_wait_start = os::elapsedTime();
3701 // We have to wait until the CM threads finish scanning the
3702 // root regions as it's the only way to ensure that all the
3703 // objects on them have been correctly scanned before we start
3704 // moving them during the GC.
3705 bool waited = _cm->root_regions()->wait_until_scan_finished();
3706 double wait_time_ms = 0.0;
3707 if (waited) {
3708 double scan_wait_end = os::elapsedTime();
3709 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3710 }
3711 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3712 }
3713
3714 bool
3715 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3716 assert_at_safepoint(true /* should_be_vm_thread */);
3717 guarantee(!is_gc_active(), "collection is not reentrant");
3718
3719 if (GC_locker::check_active_before_gc()) {
3720 return false;
3721 }
3722
3723 _gc_timer_stw->register_gc_start();
3724
3725 GCIdMark gc_id_mark;
3726 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3727
3728 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3729 ResourceMark rm;
3730
3731 wait_for_root_region_scanning();
3732
3733 G1Log::update_level();
3734 print_heap_before_gc();
3735 trace_heap_before_gc(_gc_tracer_stw);
3736
3737 verify_region_sets_optional();
3738 verify_dirty_young_regions();
3739
3740 // This call will decide whether this pause is an initial-mark
3741 // pause. If it is, during_initial_mark_pause() will return true
3742 // for the duration of this pause.
3743 g1_policy()->decide_on_conc_mark_initiation();
3744
3745 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3746 assert(!collector_state()->during_initial_mark_pause() ||
3747 collector_state()->gcs_are_young(), "sanity");
3748
3749 // We also do not allow mixed GCs during marking.
3750 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3751
3752 // Record whether this pause is an initial mark. When the current
3753 // thread has completed its logging output and it's safe to signal
3754 // the CM thread, the flag's value in the policy has been reset.
3755 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3756
3757 // Inner scope for scope based logging, timers, and stats collection
3758 {
3759 EvacuationInfo evacuation_info;
3760
3761 if (collector_state()->during_initial_mark_pause()) {
3762 // We are about to start a marking cycle, so we increment the
3763 // full collection counter.
3764 increment_old_marking_cycles_started();
3765 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3766 }
3767
3768 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3769
3770 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3771
3772 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3773 workers()->active_workers(),
3774 Threads::number_of_non_daemon_threads());
3775 workers()->set_active_workers(active_workers);
3776
3777 double pause_start_sec = os::elapsedTime();
3778 g1_policy()->note_gc_start(active_workers);
3779 log_gc_header();
3780
3781 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3782 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3783
3784 // If the secondary_free_list is not empty, append it to the
3785 // free_list. No need to wait for the cleanup operation to finish;
3786 // the region allocation code will check the secondary_free_list
3787 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3788 // set, skip this step so that the region allocation code has to
3789 // get entries from the secondary_free_list.
3790 if (!G1StressConcRegionFreeing) {
3791 append_secondary_free_list_if_not_empty_with_lock();
3792 }
3793
3794 assert(check_young_list_well_formed(), "young list should be well formed");
3795
3796 // Don't dynamically change the number of GC threads this early. A value of
3797 // 0 is used to indicate serial work. When parallel work is done,
3798 // it will be set.
3799
3800 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3801 IsGCActiveMark x;
3802
3803 gc_prologue(false);
3804 increment_total_collections(false /* full gc */);
3805 increment_gc_time_stamp();
3806
3807 verify_before_gc();
3808
3809 check_bitmaps("GC Start");
3810
3811 #if defined(COMPILER2) || INCLUDE_JVMCI
3812 DerivedPointerTable::clear();
3813 #endif
3814
3815 // Please see comment in g1CollectedHeap.hpp and
3816 // G1CollectedHeap::ref_processing_init() to see how
3817 // reference processing currently works in G1.
3818
3819 // Enable discovery in the STW reference processor
3820 ref_processor_stw()->enable_discovery();
3821
3822 {
3823 // We want to temporarily turn off discovery by the
3824 // CM ref processor, if necessary, and turn it back on
3825 // on again later if we do. Using a scoped
3826 // NoRefDiscovery object will do this.
3827 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3828
3829 // Forget the current alloc region (we might even choose it to be part
3830 // of the collection set!).
3831 _allocator->release_mutator_alloc_region();
3832
3833 // We should call this after we retire the mutator alloc
3834 // region(s) so that all the ALLOC / RETIRE events are generated
3835 // before the start GC event.
3836 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3837
3838 // This timing is only used by the ergonomics to handle our pause target.
3839 // It is unclear why this should not include the full pause. We will
3840 // investigate this in CR 7178365.
3841 //
3842 // Preserving the old comment here if that helps the investigation:
3843 //
3844 // The elapsed time induced by the start time below deliberately elides
3845 // the possible verification above.
3846 double sample_start_time_sec = os::elapsedTime();
3847
3848 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3849
3850 if (collector_state()->during_initial_mark_pause()) {
3851 concurrent_mark()->checkpointRootsInitialPre();
3852 }
3853
3854 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3855 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3856
3857 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3858
3859 // Make sure the remembered sets are up to date. This needs to be
3860 // done before register_humongous_regions_with_cset(), because the
3861 // remembered sets are used there to choose eager reclaim candidates.
3862 // If the remembered sets are not up to date we might miss some
3863 // entries that need to be handled.
3864 g1_rem_set()->cleanupHRRS();
3865
3866 register_humongous_regions_with_cset();
3867
3868 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3869
3870 _cm->note_start_of_gc();
3871 // We call this after finalize_cset() to
3872 // ensure that the CSet has been finalized.
3873 _cm->verify_no_cset_oops();
3874
3875 if (_hr_printer.is_active()) {
3876 HeapRegion* hr = g1_policy()->collection_set();
3877 while (hr != NULL) {
3878 _hr_printer.cset(hr);
3879 hr = hr->next_in_collection_set();
3880 }
3881 }
3882
3883 #ifdef ASSERT
3884 VerifyCSetClosure cl;
3885 collection_set_iterate(&cl);
3886 #endif // ASSERT
3887
3888 // Initialize the GC alloc regions.
3889 _allocator->init_gc_alloc_regions(evacuation_info);
3890
3891 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3892 pre_evacuate_collection_set();
3893
3894 // Actually do the work...
3895 evacuate_collection_set(evacuation_info, &per_thread_states);
3896
3897 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3898
3899 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3900 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3901
3902 eagerly_reclaim_humongous_regions();
3903
3904 g1_policy()->clear_collection_set();
3905
3906 // Start a new incremental collection set for the next pause.
3907 g1_policy()->start_incremental_cset_building();
3908
3909 clear_cset_fast_test();
3910
3911 _young_list->reset_sampled_info();
3912
3913 // Don't check the whole heap at this point as the
3914 // GC alloc regions from this pause have been tagged
3915 // as survivors and moved on to the survivor list.
3916 // Survivor regions will fail the !is_young() check.
3917 assert(check_young_list_empty(false /* check_heap */),
3918 "young list should be empty");
3919
3920 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3921 _young_list->first_survivor_region(),
3922 _young_list->last_survivor_region());
3923
3924 _young_list->reset_auxilary_lists();
3925
3926 if (evacuation_failed()) {
3927 set_used(recalculate_used());
3928 if (_archive_allocator != NULL) {
3929 _archive_allocator->clear_used();
3930 }
3931 for (uint i = 0; i < ParallelGCThreads; i++) {
3932 if (_evacuation_failed_info_array[i].has_failed()) {
3933 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3934 }
3935 }
3936 } else {
3937 // The "used" of the the collection set have already been subtracted
3938 // when they were freed. Add in the bytes evacuated.
3939 increase_used(g1_policy()->bytes_copied_during_gc());
3940 }
3941
3942 if (collector_state()->during_initial_mark_pause()) {
3943 // We have to do this before we notify the CM threads that
3944 // they can start working to make sure that all the
3945 // appropriate initialization is done on the CM object.
3946 concurrent_mark()->checkpointRootsInitialPost();
3947 collector_state()->set_mark_in_progress(true);
3948 // Note that we don't actually trigger the CM thread at
3949 // this point. We do that later when we're sure that
3950 // the current thread has completed its logging output.
3951 }
3952
3953 allocate_dummy_regions();
3954
3955 _allocator->init_mutator_alloc_region();
3956
3957 {
3958 size_t expand_bytes = g1_policy()->expansion_amount();
3959 if (expand_bytes > 0) {
3960 size_t bytes_before = capacity();
3961 // No need for an ergo verbose message here,
3962 // expansion_amount() does this when it returns a value > 0.
3963 double expand_ms;
3964 if (!expand(expand_bytes, &expand_ms)) {
3965 // We failed to expand the heap. Cannot do anything about it.
3966 }
3967 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3968 }
3969 }
3970
3971 // We redo the verification but now wrt to the new CSet which
3972 // has just got initialized after the previous CSet was freed.
3973 _cm->verify_no_cset_oops();
3974 _cm->note_end_of_gc();
3975
3976 // This timing is only used by the ergonomics to handle our pause target.
3977 // It is unclear why this should not include the full pause. We will
3978 // investigate this in CR 7178365.
3979 double sample_end_time_sec = os::elapsedTime();
3980 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3981 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3982 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3983
3984 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3985 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3986
3987 MemoryService::track_memory_usage();
3988
3989 // In prepare_for_verify() below we'll need to scan the deferred
3990 // update buffers to bring the RSets up-to-date if
3991 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3992 // the update buffers we'll probably need to scan cards on the
3993 // regions we just allocated to (i.e., the GC alloc
3994 // regions). However, during the last GC we called
3995 // set_saved_mark() on all the GC alloc regions, so card
3996 // scanning might skip the [saved_mark_word()...top()] area of
3997 // those regions (i.e., the area we allocated objects into
3998 // during the last GC). But it shouldn't. Given that
3999 // saved_mark_word() is conditional on whether the GC time stamp
4000 // on the region is current or not, by incrementing the GC time
4001 // stamp here we invalidate all the GC time stamps on all the
4002 // regions and saved_mark_word() will simply return top() for
4003 // all the regions. This is a nicer way of ensuring this rather
4004 // than iterating over the regions and fixing them. In fact, the
4005 // GC time stamp increment here also ensures that
4006 // saved_mark_word() will return top() between pauses, i.e.,
4007 // during concurrent refinement. So we don't need the
4008 // is_gc_active() check to decided which top to use when
4009 // scanning cards (see CR 7039627).
4010 increment_gc_time_stamp();
4011
4012 verify_after_gc();
4013 check_bitmaps("GC End");
4014
4015 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4016 ref_processor_stw()->verify_no_references_recorded();
4017
4018 // CM reference discovery will be re-enabled if necessary.
4019 }
4020
4021 // We should do this after we potentially expand the heap so
4022 // that all the COMMIT events are generated before the end GC
4023 // event, and after we retire the GC alloc regions so that all
4024 // RETIRE events are generated before the end GC event.
4025 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4026
4027 #ifdef TRACESPINNING
4028 ParallelTaskTerminator::print_termination_counts();
4029 #endif
4030
4031 gc_epilogue(false);
4032 }
4033
4034 // Print the remainder of the GC log output.
4035 log_gc_footer(os::elapsedTime() - pause_start_sec);
4036
4037 // It is not yet to safe to tell the concurrent mark to
4038 // start as we have some optional output below. We don't want the
4039 // output from the concurrent mark thread interfering with this
4040 // logging output either.
4041
4042 _hrm.verify_optional();
4043 verify_region_sets_optional();
4044
4045 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4046 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4047
4048 print_heap_after_gc();
4049 trace_heap_after_gc(_gc_tracer_stw);
4050
4051 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4052 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4053 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4054 // before any GC notifications are raised.
4055 g1mm()->update_sizes();
4056
4057 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4058 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4059 _gc_timer_stw->register_gc_end();
4060 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4061 }
4062 // It should now be safe to tell the concurrent mark thread to start
4063 // without its logging output interfering with the logging output
4064 // that came from the pause.
4065
4066 if (should_start_conc_mark) {
4067 // CAUTION: after the doConcurrentMark() call below,
4068 // the concurrent marking thread(s) could be running
4069 // concurrently with us. Make sure that anything after
4070 // this point does not assume that we are the only GC thread
4071 // running. Note: of course, the actual marking work will
4072 // not start until the safepoint itself is released in
4073 // SuspendibleThreadSet::desynchronize().
4074 doConcurrentMark();
4075 }
4076
4077 return true;
4078 }
4079
4080 void G1CollectedHeap::remove_self_forwarding_pointers() {
4081 double remove_self_forwards_start = os::elapsedTime();
4082
4083 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4084 workers()->run_task(&rsfp_task);
4085
4086 // Now restore saved marks, if any.
4087 for (uint i = 0; i < ParallelGCThreads; i++) {
4088 OopAndMarkOopStack& cur = _preserved_objs[i];
4089 while (!cur.is_empty()) {
4090 OopAndMarkOop elem = cur.pop();
4091 elem.set_mark();
4092 }
4093 cur.clear(true);
4094 }
4095
4096 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4097 }
4098
4099 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4100 if (!_evacuation_failed) {
4101 _evacuation_failed = true;
4102 }
4103
4104 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4105
4106 // We want to call the "for_promotion_failure" version only in the
4107 // case of a promotion failure.
4108 if (m->must_be_preserved_for_promotion_failure(obj)) {
4109 OopAndMarkOop elem(obj, m);
4110 _preserved_objs[worker_id].push(elem);
4111 }
4112 }
4113
4114 class G1ParEvacuateFollowersClosure : public VoidClosure {
4115 private:
4116 double _start_term;
4117 double _term_time;
4118 size_t _term_attempts;
4119
4120 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4121 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4122 protected:
4123 G1CollectedHeap* _g1h;
4124 G1ParScanThreadState* _par_scan_state;
4125 RefToScanQueueSet* _queues;
4126 ParallelTaskTerminator* _terminator;
4127
4128 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4129 RefToScanQueueSet* queues() { return _queues; }
4130 ParallelTaskTerminator* terminator() { return _terminator; }
4131
4132 public:
4133 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4134 G1ParScanThreadState* par_scan_state,
4135 RefToScanQueueSet* queues,
4136 ParallelTaskTerminator* terminator)
4137 : _g1h(g1h), _par_scan_state(par_scan_state),
4138 _queues(queues), _terminator(terminator),
4139 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4140
4141 void do_void();
4142
4143 double term_time() const { return _term_time; }
4144 size_t term_attempts() const { return _term_attempts; }
4145
4146 private:
4147 inline bool offer_termination();
4148 };
4149
4150 bool G1ParEvacuateFollowersClosure::offer_termination() {
4151 G1ParScanThreadState* const pss = par_scan_state();
4152 start_term_time();
4153 const bool res = terminator()->offer_termination();
4154 end_term_time();
4155 return res;
4156 }
4157
4158 void G1ParEvacuateFollowersClosure::do_void() {
4159 G1ParScanThreadState* const pss = par_scan_state();
4160 pss->trim_queue();
4161 do {
4162 pss->steal_and_trim_queue(queues());
4163 } while (!offer_termination());
4164 }
4165
4166 class G1ParTask : public AbstractGangTask {
4167 protected:
4168 G1CollectedHeap* _g1h;
4169 G1ParScanThreadStateSet* _pss;
4170 RefToScanQueueSet* _queues;
4171 G1RootProcessor* _root_processor;
4172 ParallelTaskTerminator _terminator;
4173 uint _n_workers;
4174
4175 public:
4176 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4177 : AbstractGangTask("G1 collection"),
4178 _g1h(g1h),
4179 _pss(per_thread_states),
4180 _queues(task_queues),
4181 _root_processor(root_processor),
4182 _terminator(n_workers, _queues),
4183 _n_workers(n_workers)
4184 {}
4185
4186 void work(uint worker_id) {
4187 if (worker_id >= _n_workers) return; // no work needed this round
4188
4189 double start_sec = os::elapsedTime();
4190 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4191
4192 {
4193 ResourceMark rm;
4194 HandleMark hm;
4195
4196 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4197
4198 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4199 pss->set_ref_processor(rp);
4200
4201 double start_strong_roots_sec = os::elapsedTime();
4202
4203 _root_processor->evacuate_roots(pss->closures(), worker_id);
4204
4205 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4206
4207 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4208 // treating the nmethods visited to act as roots for concurrent marking.
4209 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4210 // objects copied by the current evacuation.
4211 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4212 pss->closures()->weak_codeblobs(),
4213 worker_id);
4214
4215 _pss->add_cards_scanned(worker_id, cards_scanned);
4216
4217 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4218
4219 double term_sec = 0.0;
4220 size_t evac_term_attempts = 0;
4221 {
4222 double start = os::elapsedTime();
4223 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4224 evac.do_void();
4225
4226 evac_term_attempts = evac.term_attempts();
4227 term_sec = evac.term_time();
4228 double elapsed_sec = os::elapsedTime() - start;
4229 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4230 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4231 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4232 }
4233
4234 assert(pss->queue_is_empty(), "should be empty");
4235
4236 if (PrintTerminationStats) {
4237 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4238 size_t lab_waste;
4239 size_t lab_undo_waste;
4240 pss->waste(lab_waste, lab_undo_waste);
4241 _g1h->print_termination_stats(gclog_or_tty,
4242 worker_id,
4243 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4244 strong_roots_sec * 1000.0, /* strong roots time */
4245 term_sec * 1000.0, /* evac term time */
4246 evac_term_attempts, /* evac term attempts */
4247 lab_waste, /* alloc buffer waste */
4248 lab_undo_waste /* undo waste */
4249 );
4250 }
4251
4252 // Close the inner scope so that the ResourceMark and HandleMark
4253 // destructors are executed here and are included as part of the
4254 // "GC Worker Time".
4255 }
4256 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4257 }
4258 };
4259
4260 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4261 st->print_raw_cr("GC Termination Stats");
4262 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4263 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4264 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4265 }
4266
4267 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4268 uint worker_id,
4269 double elapsed_ms,
4270 double strong_roots_ms,
4271 double term_ms,
4272 size_t term_attempts,
4273 size_t alloc_buffer_waste,
4274 size_t undo_waste) const {
4275 st->print_cr("%3d %9.2f %9.2f %6.2f "
4276 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4277 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4278 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4279 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4280 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4281 alloc_buffer_waste * HeapWordSize / K,
4282 undo_waste * HeapWordSize / K);
4283 }
4284
4285 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4286 private:
4287 BoolObjectClosure* _is_alive;
4288 int _initial_string_table_size;
4289 int _initial_symbol_table_size;
4290
4291 bool _process_strings;
4292 int _strings_processed;
4293 int _strings_removed;
4294
4295 bool _process_symbols;
4296 int _symbols_processed;
4297 int _symbols_removed;
4298
4299 public:
4300 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4301 AbstractGangTask("String/Symbol Unlinking"),
4302 _is_alive(is_alive),
4303 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4304 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4305
4306 _initial_string_table_size = StringTable::the_table()->table_size();
4307 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4308 if (process_strings) {
4309 StringTable::clear_parallel_claimed_index();
4310 }
4311 if (process_symbols) {
4312 SymbolTable::clear_parallel_claimed_index();
4313 }
4314 }
4315
4316 ~G1StringSymbolTableUnlinkTask() {
4317 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4318 "claim value %d after unlink less than initial string table size %d",
4319 StringTable::parallel_claimed_index(), _initial_string_table_size);
4320 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4321 "claim value %d after unlink less than initial symbol table size %d",
4322 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4323
4324 if (G1TraceStringSymbolTableScrubbing) {
4325 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4326 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4327 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4328 strings_processed(), strings_removed(),
4329 symbols_processed(), symbols_removed());
4330 }
4331 }
4332
4333 void work(uint worker_id) {
4334 int strings_processed = 0;
4335 int strings_removed = 0;
4336 int symbols_processed = 0;
4337 int symbols_removed = 0;
4338 if (_process_strings) {
4339 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4340 Atomic::add(strings_processed, &_strings_processed);
4341 Atomic::add(strings_removed, &_strings_removed);
4342 }
4343 if (_process_symbols) {
4344 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4345 Atomic::add(symbols_processed, &_symbols_processed);
4346 Atomic::add(symbols_removed, &_symbols_removed);
4347 }
4348 }
4349
4350 size_t strings_processed() const { return (size_t)_strings_processed; }
4351 size_t strings_removed() const { return (size_t)_strings_removed; }
4352
4353 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4354 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4355 };
4356
4357 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4358 private:
4359 static Monitor* _lock;
4360
4361 BoolObjectClosure* const _is_alive;
4362 const bool _unloading_occurred;
4363 const uint _num_workers;
4364
4365 // Variables used to claim nmethods.
4366 nmethod* _first_nmethod;
4367 volatile nmethod* _claimed_nmethod;
4368
4369 // The list of nmethods that need to be processed by the second pass.
4370 volatile nmethod* _postponed_list;
4371 volatile uint _num_entered_barrier;
4372
4373 public:
4374 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4375 _is_alive(is_alive),
4376 _unloading_occurred(unloading_occurred),
4377 _num_workers(num_workers),
4378 _first_nmethod(NULL),
4379 _claimed_nmethod(NULL),
4380 _postponed_list(NULL),
4381 _num_entered_barrier(0)
4382 {
4383 nmethod::increase_unloading_clock();
4384 // Get first alive nmethod
4385 NMethodIterator iter = NMethodIterator();
4386 if(iter.next_alive()) {
4387 _first_nmethod = iter.method();
4388 }
4389 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4390 }
4391
4392 ~G1CodeCacheUnloadingTask() {
4393 CodeCache::verify_clean_inline_caches();
4394
4395 CodeCache::set_needs_cache_clean(false);
4396 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4397
4398 CodeCache::verify_icholder_relocations();
4399 }
4400
4401 private:
4402 void add_to_postponed_list(nmethod* nm) {
4403 nmethod* old;
4404 do {
4405 old = (nmethod*)_postponed_list;
4406 nm->set_unloading_next(old);
4407 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4408 }
4409
4410 void clean_nmethod(nmethod* nm) {
4411 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4412
4413 if (postponed) {
4414 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4415 add_to_postponed_list(nm);
4416 }
4417
4418 // Mark that this thread has been cleaned/unloaded.
4419 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4420 nm->set_unloading_clock(nmethod::global_unloading_clock());
4421 }
4422
4423 void clean_nmethod_postponed(nmethod* nm) {
4424 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4425 }
4426
4427 static const int MaxClaimNmethods = 16;
4428
4429 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4430 nmethod* first;
4431 NMethodIterator last;
4432
4433 do {
4434 *num_claimed_nmethods = 0;
4435
4436 first = (nmethod*)_claimed_nmethod;
4437 last = NMethodIterator(first);
4438
4439 if (first != NULL) {
4440
4441 for (int i = 0; i < MaxClaimNmethods; i++) {
4442 if (!last.next_alive()) {
4443 break;
4444 }
4445 claimed_nmethods[i] = last.method();
4446 (*num_claimed_nmethods)++;
4447 }
4448 }
4449
4450 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4451 }
4452
4453 nmethod* claim_postponed_nmethod() {
4454 nmethod* claim;
4455 nmethod* next;
4456
4457 do {
4458 claim = (nmethod*)_postponed_list;
4459 if (claim == NULL) {
4460 return NULL;
4461 }
4462
4463 next = claim->unloading_next();
4464
4465 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4466
4467 return claim;
4468 }
4469
4470 public:
4471 // Mark that we're done with the first pass of nmethod cleaning.
4472 void barrier_mark(uint worker_id) {
4473 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4474 _num_entered_barrier++;
4475 if (_num_entered_barrier == _num_workers) {
4476 ml.notify_all();
4477 }
4478 }
4479
4480 // See if we have to wait for the other workers to
4481 // finish their first-pass nmethod cleaning work.
4482 void barrier_wait(uint worker_id) {
4483 if (_num_entered_barrier < _num_workers) {
4484 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4485 while (_num_entered_barrier < _num_workers) {
4486 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4487 }
4488 }
4489 }
4490
4491 // Cleaning and unloading of nmethods. Some work has to be postponed
4492 // to the second pass, when we know which nmethods survive.
4493 void work_first_pass(uint worker_id) {
4494 // The first nmethods is claimed by the first worker.
4495 if (worker_id == 0 && _first_nmethod != NULL) {
4496 clean_nmethod(_first_nmethod);
4497 _first_nmethod = NULL;
4498 }
4499
4500 int num_claimed_nmethods;
4501 nmethod* claimed_nmethods[MaxClaimNmethods];
4502
4503 while (true) {
4504 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4505
4506 if (num_claimed_nmethods == 0) {
4507 break;
4508 }
4509
4510 for (int i = 0; i < num_claimed_nmethods; i++) {
4511 clean_nmethod(claimed_nmethods[i]);
4512 }
4513 }
4514 }
4515
4516 void work_second_pass(uint worker_id) {
4517 nmethod* nm;
4518 // Take care of postponed nmethods.
4519 while ((nm = claim_postponed_nmethod()) != NULL) {
4520 clean_nmethod_postponed(nm);
4521 }
4522 }
4523 };
4524
4525 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4526
4527 class G1KlassCleaningTask : public StackObj {
4528 BoolObjectClosure* _is_alive;
4529 volatile jint _clean_klass_tree_claimed;
4530 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4531
4532 public:
4533 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4534 _is_alive(is_alive),
4535 _clean_klass_tree_claimed(0),
4536 _klass_iterator() {
4537 }
4538
4539 private:
4540 bool claim_clean_klass_tree_task() {
4541 if (_clean_klass_tree_claimed) {
4542 return false;
4543 }
4544
4545 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4546 }
4547
4548 InstanceKlass* claim_next_klass() {
4549 Klass* klass;
4550 do {
4551 klass =_klass_iterator.next_klass();
4552 } while (klass != NULL && !klass->is_instance_klass());
4553
4554 // this can be null so don't call InstanceKlass::cast
4555 return static_cast<InstanceKlass*>(klass);
4556 }
4557
4558 public:
4559
4560 void clean_klass(InstanceKlass* ik) {
4561 ik->clean_weak_instanceklass_links(_is_alive);
4562 }
4563
4564 void work() {
4565 ResourceMark rm;
4566
4567 // One worker will clean the subklass/sibling klass tree.
4568 if (claim_clean_klass_tree_task()) {
4569 Klass::clean_subklass_tree(_is_alive);
4570 }
4571
4572 // All workers will help cleaning the classes,
4573 InstanceKlass* klass;
4574 while ((klass = claim_next_klass()) != NULL) {
4575 clean_klass(klass);
4576 }
4577 }
4578 };
4579
4580 // To minimize the remark pause times, the tasks below are done in parallel.
4581 class G1ParallelCleaningTask : public AbstractGangTask {
4582 private:
4583 G1StringSymbolTableUnlinkTask _string_symbol_task;
4584 G1CodeCacheUnloadingTask _code_cache_task;
4585 G1KlassCleaningTask _klass_cleaning_task;
4586
4587 public:
4588 // The constructor is run in the VMThread.
4589 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4590 AbstractGangTask("Parallel Cleaning"),
4591 _string_symbol_task(is_alive, process_strings, process_symbols),
4592 _code_cache_task(num_workers, is_alive, unloading_occurred),
4593 _klass_cleaning_task(is_alive) {
4594 }
4595
4596 // The parallel work done by all worker threads.
4597 void work(uint worker_id) {
4598 // Do first pass of code cache cleaning.
4599 _code_cache_task.work_first_pass(worker_id);
4600
4601 // Let the threads mark that the first pass is done.
4602 _code_cache_task.barrier_mark(worker_id);
4603
4604 // Clean the Strings and Symbols.
4605 _string_symbol_task.work(worker_id);
4606
4607 // Wait for all workers to finish the first code cache cleaning pass.
4608 _code_cache_task.barrier_wait(worker_id);
4609
4610 // Do the second code cache cleaning work, which realize on
4611 // the liveness information gathered during the first pass.
4612 _code_cache_task.work_second_pass(worker_id);
4613
4614 // Clean all klasses that were not unloaded.
4615 _klass_cleaning_task.work();
4616 }
4617 };
4618
4619
4620 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4621 bool process_strings,
4622 bool process_symbols,
4623 bool class_unloading_occurred) {
4624 uint n_workers = workers()->active_workers();
4625
4626 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4627 n_workers, class_unloading_occurred);
4628 workers()->run_task(&g1_unlink_task);
4629 }
4630
4631 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4632 bool process_strings, bool process_symbols) {
4633 {
4634 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4635 workers()->run_task(&g1_unlink_task);
4636 }
4637
4638 if (G1StringDedup::is_enabled()) {
4639 G1StringDedup::unlink(is_alive);
4640 }
4641 }
4642
4643 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4644 private:
4645 DirtyCardQueueSet* _queue;
4646 public:
4647 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4648
4649 virtual void work(uint worker_id) {
4650 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4651 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4652
4653 RedirtyLoggedCardTableEntryClosure cl;
4654 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4655
4656 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4657 }
4658 };
4659
4660 void G1CollectedHeap::redirty_logged_cards() {
4661 double redirty_logged_cards_start = os::elapsedTime();
4662
4663 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4664 dirty_card_queue_set().reset_for_par_iteration();
4665 workers()->run_task(&redirty_task);
4666
4667 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4668 dcq.merge_bufferlists(&dirty_card_queue_set());
4669 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4670
4671 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4672 }
4673
4674 // Weak Reference Processing support
4675
4676 // An always "is_alive" closure that is used to preserve referents.
4677 // If the object is non-null then it's alive. Used in the preservation
4678 // of referent objects that are pointed to by reference objects
4679 // discovered by the CM ref processor.
4680 class G1AlwaysAliveClosure: public BoolObjectClosure {
4681 G1CollectedHeap* _g1;
4682 public:
4683 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4684 bool do_object_b(oop p) {
4685 if (p != NULL) {
4686 return true;
4687 }
4688 return false;
4689 }
4690 };
4691
4692 bool G1STWIsAliveClosure::do_object_b(oop p) {
4693 // An object is reachable if it is outside the collection set,
4694 // or is inside and copied.
4695 return !_g1->is_in_cset(p) || p->is_forwarded();
4696 }
4697
4698 // Non Copying Keep Alive closure
4699 class G1KeepAliveClosure: public OopClosure {
4700 G1CollectedHeap* _g1;
4701 public:
4702 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4703 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4704 void do_oop(oop* p) {
4705 oop obj = *p;
4706 assert(obj != NULL, "the caller should have filtered out NULL values");
4707
4708 const InCSetState cset_state = _g1->in_cset_state(obj);
4709 if (!cset_state.is_in_cset_or_humongous()) {
4710 return;
4711 }
4712 if (cset_state.is_in_cset()) {
4713 assert( obj->is_forwarded(), "invariant" );
4714 *p = obj->forwardee();
4715 } else {
4716 assert(!obj->is_forwarded(), "invariant" );
4717 assert(cset_state.is_humongous(),
4718 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4719 _g1->set_humongous_is_live(obj);
4720 }
4721 }
4722 };
4723
4724 // Copying Keep Alive closure - can be called from both
4725 // serial and parallel code as long as different worker
4726 // threads utilize different G1ParScanThreadState instances
4727 // and different queues.
4728
4729 class G1CopyingKeepAliveClosure: public OopClosure {
4730 G1CollectedHeap* _g1h;
4731 OopClosure* _copy_non_heap_obj_cl;
4732 G1ParScanThreadState* _par_scan_state;
4733
4734 public:
4735 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4736 OopClosure* non_heap_obj_cl,
4737 G1ParScanThreadState* pss):
4738 _g1h(g1h),
4739 _copy_non_heap_obj_cl(non_heap_obj_cl),
4740 _par_scan_state(pss)
4741 {}
4742
4743 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4744 virtual void do_oop( oop* p) { do_oop_work(p); }
4745
4746 template <class T> void do_oop_work(T* p) {
4747 oop obj = oopDesc::load_decode_heap_oop(p);
4748
4749 if (_g1h->is_in_cset_or_humongous(obj)) {
4750 // If the referent object has been forwarded (either copied
4751 // to a new location or to itself in the event of an
4752 // evacuation failure) then we need to update the reference
4753 // field and, if both reference and referent are in the G1
4754 // heap, update the RSet for the referent.
4755 //
4756 // If the referent has not been forwarded then we have to keep
4757 // it alive by policy. Therefore we have copy the referent.
4758 //
4759 // If the reference field is in the G1 heap then we can push
4760 // on the PSS queue. When the queue is drained (after each
4761 // phase of reference processing) the object and it's followers
4762 // will be copied, the reference field set to point to the
4763 // new location, and the RSet updated. Otherwise we need to
4764 // use the the non-heap or metadata closures directly to copy
4765 // the referent object and update the pointer, while avoiding
4766 // updating the RSet.
4767
4768 if (_g1h->is_in_g1_reserved(p)) {
4769 _par_scan_state->push_on_queue(p);
4770 } else {
4771 assert(!Metaspace::contains((const void*)p),
4772 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4773 _copy_non_heap_obj_cl->do_oop(p);
4774 }
4775 }
4776 }
4777 };
4778
4779 // Serial drain queue closure. Called as the 'complete_gc'
4780 // closure for each discovered list in some of the
4781 // reference processing phases.
4782
4783 class G1STWDrainQueueClosure: public VoidClosure {
4784 protected:
4785 G1CollectedHeap* _g1h;
4786 G1ParScanThreadState* _par_scan_state;
4787
4788 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4789
4790 public:
4791 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4792 _g1h(g1h),
4793 _par_scan_state(pss)
4794 { }
4795
4796 void do_void() {
4797 G1ParScanThreadState* const pss = par_scan_state();
4798 pss->trim_queue();
4799 }
4800 };
4801
4802 // Parallel Reference Processing closures
4803
4804 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4805 // processing during G1 evacuation pauses.
4806
4807 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4808 private:
4809 G1CollectedHeap* _g1h;
4810 G1ParScanThreadStateSet* _pss;
4811 RefToScanQueueSet* _queues;
4812 WorkGang* _workers;
4813 uint _active_workers;
4814
4815 public:
4816 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4817 G1ParScanThreadStateSet* per_thread_states,
4818 WorkGang* workers,
4819 RefToScanQueueSet *task_queues,
4820 uint n_workers) :
4821 _g1h(g1h),
4822 _pss(per_thread_states),
4823 _queues(task_queues),
4824 _workers(workers),
4825 _active_workers(n_workers)
4826 {
4827 assert(n_workers > 0, "shouldn't call this otherwise");
4828 }
4829
4830 // Executes the given task using concurrent marking worker threads.
4831 virtual void execute(ProcessTask& task);
4832 virtual void execute(EnqueueTask& task);
4833 };
4834
4835 // Gang task for possibly parallel reference processing
4836
4837 class G1STWRefProcTaskProxy: public AbstractGangTask {
4838 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4839 ProcessTask& _proc_task;
4840 G1CollectedHeap* _g1h;
4841 G1ParScanThreadStateSet* _pss;
4842 RefToScanQueueSet* _task_queues;
4843 ParallelTaskTerminator* _terminator;
4844
4845 public:
4846 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4847 G1CollectedHeap* g1h,
4848 G1ParScanThreadStateSet* per_thread_states,
4849 RefToScanQueueSet *task_queues,
4850 ParallelTaskTerminator* terminator) :
4851 AbstractGangTask("Process reference objects in parallel"),
4852 _proc_task(proc_task),
4853 _g1h(g1h),
4854 _pss(per_thread_states),
4855 _task_queues(task_queues),
4856 _terminator(terminator)
4857 {}
4858
4859 virtual void work(uint worker_id) {
4860 // The reference processing task executed by a single worker.
4861 ResourceMark rm;
4862 HandleMark hm;
4863
4864 G1STWIsAliveClosure is_alive(_g1h);
4865
4866 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4867 pss->set_ref_processor(NULL);
4868
4869 // Keep alive closure.
4870 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4871
4872 // Complete GC closure
4873 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4874
4875 // Call the reference processing task's work routine.
4876 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4877
4878 // Note we cannot assert that the refs array is empty here as not all
4879 // of the processing tasks (specifically phase2 - pp2_work) execute
4880 // the complete_gc closure (which ordinarily would drain the queue) so
4881 // the queue may not be empty.
4882 }
4883 };
4884
4885 // Driver routine for parallel reference processing.
4886 // Creates an instance of the ref processing gang
4887 // task and has the worker threads execute it.
4888 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4889 assert(_workers != NULL, "Need parallel worker threads.");
4890
4891 ParallelTaskTerminator terminator(_active_workers, _queues);
4892 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4893
4894 _workers->run_task(&proc_task_proxy);
4895 }
4896
4897 // Gang task for parallel reference enqueueing.
4898
4899 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4900 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4901 EnqueueTask& _enq_task;
4902
4903 public:
4904 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4905 AbstractGangTask("Enqueue reference objects in parallel"),
4906 _enq_task(enq_task)
4907 { }
4908
4909 virtual void work(uint worker_id) {
4910 _enq_task.work(worker_id);
4911 }
4912 };
4913
4914 // Driver routine for parallel reference enqueueing.
4915 // Creates an instance of the ref enqueueing gang
4916 // task and has the worker threads execute it.
4917
4918 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4919 assert(_workers != NULL, "Need parallel worker threads.");
4920
4921 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4922
4923 _workers->run_task(&enq_task_proxy);
4924 }
4925
4926 // End of weak reference support closures
4927
4928 // Abstract task used to preserve (i.e. copy) any referent objects
4929 // that are in the collection set and are pointed to by reference
4930 // objects discovered by the CM ref processor.
4931
4932 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4933 protected:
4934 G1CollectedHeap* _g1h;
4935 G1ParScanThreadStateSet* _pss;
4936 RefToScanQueueSet* _queues;
4937 ParallelTaskTerminator _terminator;
4938 uint _n_workers;
4939
4940 public:
4941 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4942 AbstractGangTask("ParPreserveCMReferents"),
4943 _g1h(g1h),
4944 _pss(per_thread_states),
4945 _queues(task_queues),
4946 _terminator(workers, _queues),
4947 _n_workers(workers)
4948 { }
4949
4950 void work(uint worker_id) {
4951 ResourceMark rm;
4952 HandleMark hm;
4953
4954 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4955 pss->set_ref_processor(NULL);
4956 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4957
4958 // Is alive closure
4959 G1AlwaysAliveClosure always_alive(_g1h);
4960
4961 // Copying keep alive closure. Applied to referent objects that need
4962 // to be copied.
4963 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4964
4965 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4966
4967 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4968 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4969
4970 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4971 // So this must be true - but assert just in case someone decides to
4972 // change the worker ids.
4973 assert(worker_id < limit, "sanity");
4974 assert(!rp->discovery_is_atomic(), "check this code");
4975
4976 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4977 for (uint idx = worker_id; idx < limit; idx += stride) {
4978 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4979
4980 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4981 while (iter.has_next()) {
4982 // Since discovery is not atomic for the CM ref processor, we
4983 // can see some null referent objects.
4984 iter.load_ptrs(DEBUG_ONLY(true));
4985 oop ref = iter.obj();
4986
4987 // This will filter nulls.
4988 if (iter.is_referent_alive()) {
4989 iter.make_referent_alive();
4990 }
4991 iter.move_to_next();
4992 }
4993 }
4994
4995 // Drain the queue - which may cause stealing
4996 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4997 drain_queue.do_void();
4998 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4999 assert(pss->queue_is_empty(), "should be");
5000 }
5001 };
5002
5003 // Weak Reference processing during an evacuation pause (part 1).
5004 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5005 double ref_proc_start = os::elapsedTime();
5006
5007 ReferenceProcessor* rp = _ref_processor_stw;
5008 assert(rp->discovery_enabled(), "should have been enabled");
5009
5010 // Any reference objects, in the collection set, that were 'discovered'
5011 // by the CM ref processor should have already been copied (either by
5012 // applying the external root copy closure to the discovered lists, or
5013 // by following an RSet entry).
5014 //
5015 // But some of the referents, that are in the collection set, that these
5016 // reference objects point to may not have been copied: the STW ref
5017 // processor would have seen that the reference object had already
5018 // been 'discovered' and would have skipped discovering the reference,
5019 // but would not have treated the reference object as a regular oop.
5020 // As a result the copy closure would not have been applied to the
5021 // referent object.
5022 //
5023 // We need to explicitly copy these referent objects - the references
5024 // will be processed at the end of remarking.
5025 //
5026 // We also need to do this copying before we process the reference
5027 // objects discovered by the STW ref processor in case one of these
5028 // referents points to another object which is also referenced by an
5029 // object discovered by the STW ref processor.
5030
5031 uint no_of_gc_workers = workers()->active_workers();
5032
5033 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5034 per_thread_states,
5035 no_of_gc_workers,
5036 _task_queues);
5037
5038 workers()->run_task(&keep_cm_referents);
5039
5040 // Closure to test whether a referent is alive.
5041 G1STWIsAliveClosure is_alive(this);
5042
5043 // Even when parallel reference processing is enabled, the processing
5044 // of JNI refs is serial and performed serially by the current thread
5045 // rather than by a worker. The following PSS will be used for processing
5046 // JNI refs.
5047
5048 // Use only a single queue for this PSS.
5049 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5050 pss->set_ref_processor(NULL);
5051 assert(pss->queue_is_empty(), "pre-condition");
5052
5053 // Keep alive closure.
5054 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5055
5056 // Serial Complete GC closure
5057 G1STWDrainQueueClosure drain_queue(this, pss);
5058
5059 // Setup the soft refs policy...
5060 rp->setup_policy(false);
5061
5062 ReferenceProcessorStats stats;
5063 if (!rp->processing_is_mt()) {
5064 // Serial reference processing...
5065 stats = rp->process_discovered_references(&is_alive,
5066 &keep_alive,
5067 &drain_queue,
5068 NULL,
5069 _gc_timer_stw);
5070 } else {
5071 // Parallel reference processing
5072 assert(rp->num_q() == no_of_gc_workers, "sanity");
5073 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5074
5075 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5076 stats = rp->process_discovered_references(&is_alive,
5077 &keep_alive,
5078 &drain_queue,
5079 &par_task_executor,
5080 _gc_timer_stw);
5081 }
5082
5083 _gc_tracer_stw->report_gc_reference_stats(stats);
5084
5085 // We have completed copying any necessary live referent objects.
5086 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5087
5088 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5089 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5090 }
5091
5092 // Weak Reference processing during an evacuation pause (part 2).
5093 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5094 double ref_enq_start = os::elapsedTime();
5095
5096 ReferenceProcessor* rp = _ref_processor_stw;
5097 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5098
5099 // Now enqueue any remaining on the discovered lists on to
5100 // the pending list.
5101 if (!rp->processing_is_mt()) {
5102 // Serial reference processing...
5103 rp->enqueue_discovered_references();
5104 } else {
5105 // Parallel reference enqueueing
5106
5107 uint n_workers = workers()->active_workers();
5108
5109 assert(rp->num_q() == n_workers, "sanity");
5110 assert(n_workers <= rp->max_num_q(), "sanity");
5111
5112 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5113 rp->enqueue_discovered_references(&par_task_executor);
5114 }
5115
5116 rp->verify_no_references_recorded();
5117 assert(!rp->discovery_enabled(), "should have been disabled");
5118
5119 // FIXME
5120 // CM's reference processing also cleans up the string and symbol tables.
5121 // Should we do that here also? We could, but it is a serial operation
5122 // and could significantly increase the pause time.
5123
5124 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5125 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5126 }
5127
5128 void G1CollectedHeap::pre_evacuate_collection_set() {
5129 _expand_heap_after_alloc_failure = true;
5130 _evacuation_failed = false;
5131
5132 // Disable the hot card cache.
5133 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5134 hot_card_cache->reset_hot_cache_claimed_index();
5135 hot_card_cache->set_use_cache(false);
5136
5137 }
5138
5139 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5140 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5141
5142 // Should G1EvacuationFailureALot be in effect for this GC?
5143 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5144
5145 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5146 double start_par_time_sec = os::elapsedTime();
5147 double end_par_time_sec;
5148
5149 {
5150 const uint n_workers = workers()->active_workers();
5151 G1RootProcessor root_processor(this, n_workers);
5152 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5153 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5154 if (collector_state()->during_initial_mark_pause()) {
5155 ClassLoaderDataGraph::clear_claimed_marks();
5156 }
5157
5158 // The individual threads will set their evac-failure closures.
5159 if (PrintTerminationStats) {
5160 print_termination_stats_hdr(gclog_or_tty);
5161 }
5162
5163 workers()->run_task(&g1_par_task);
5164 end_par_time_sec = os::elapsedTime();
5165
5166 // Closing the inner scope will execute the destructor
5167 // for the G1RootProcessor object. We record the current
5168 // elapsed time before closing the scope so that time
5169 // taken for the destructor is NOT included in the
5170 // reported parallel time.
5171 }
5172
5173 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5174
5175 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5176 phase_times->record_par_time(par_time_ms);
5177
5178 double code_root_fixup_time_ms =
5179 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5180 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5181
5182 // Process any discovered reference objects - we have
5183 // to do this _before_ we retire the GC alloc regions
5184 // as we may have to copy some 'reachable' referent
5185 // objects (and their reachable sub-graphs) that were
5186 // not copied during the pause.
5187 process_discovered_references(per_thread_states);
5188
5189 if (G1StringDedup::is_enabled()) {
5190 double fixup_start = os::elapsedTime();
5191
5192 G1STWIsAliveClosure is_alive(this);
5193 G1KeepAliveClosure keep_alive(this);
5194 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5195
5196 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5197 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5198 }
5199
5200 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5201
5202 if (evacuation_failed()) {
5203 remove_self_forwarding_pointers();
5204
5205 // Reset the G1EvacuationFailureALot counters and flags
5206 // Note: the values are reset only when an actual
5207 // evacuation failure occurs.
5208 NOT_PRODUCT(reset_evacuation_should_fail();)
5209 }
5210
5211 // Enqueue any remaining references remaining on the STW
5212 // reference processor's discovered lists. We need to do
5213 // this after the card table is cleaned (and verified) as
5214 // the act of enqueueing entries on to the pending list
5215 // will log these updates (and dirty their associated
5216 // cards). We need these updates logged to update any
5217 // RSets.
5218 enqueue_discovered_references(per_thread_states);
5219 }
5220
5221 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5222 _allocator->release_gc_alloc_regions(evacuation_info);
5223
5224 per_thread_states->flush();
5225
5226 record_obj_copy_mem_stats();
5227
5228 _survivor_evac_stats.adjust_desired_plab_sz();
5229 _old_evac_stats.adjust_desired_plab_sz();
5230
5231 // Reset and re-enable the hot card cache.
5232 // Note the counts for the cards in the regions in the
5233 // collection set are reset when the collection set is freed.
5234 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5235 hot_card_cache->reset_hot_cache();
5236 hot_card_cache->set_use_cache(true);
5237
5238 purge_code_root_memory();
5239
5240 redirty_logged_cards();
5241 #if defined(COMPILER2) || INCLUDE_JVMCI
5242 DerivedPointerTable::update_pointers();
5243 #endif
5244 }
5245
5246 void G1CollectedHeap::record_obj_copy_mem_stats() {
5247 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5248 create_g1_evac_summary(&_old_evac_stats));
5249 }
5250
5251 void G1CollectedHeap::free_region(HeapRegion* hr,
5252 FreeRegionList* free_list,
5253 bool par,
5254 bool locked) {
5255 assert(!hr->is_free(), "the region should not be free");
5256 assert(!hr->is_empty(), "the region should not be empty");
5257 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5258 assert(free_list != NULL, "pre-condition");
5259
5260 if (G1VerifyBitmaps) {
5261 MemRegion mr(hr->bottom(), hr->end());
5262 concurrent_mark()->clearRangePrevBitmap(mr);
5263 }
5264
5265 // Clear the card counts for this region.
5266 // Note: we only need to do this if the region is not young
5267 // (since we don't refine cards in young regions).
5268 if (!hr->is_young()) {
5269 _cg1r->hot_card_cache()->reset_card_counts(hr);
5270 }
5271 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5272 free_list->add_ordered(hr);
5273 }
5274
5275 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5276 FreeRegionList* free_list,
5277 bool par) {
5278 assert(hr->is_humongous(), "this is only for humongous regions");
5279 assert(free_list != NULL, "pre-condition");
5280 hr->clear_humongous();
5281 free_region(hr, free_list, par);
5282 }
5283
5284 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5285 const HeapRegionSetCount& humongous_regions_removed) {
5286 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5287 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5288 _old_set.bulk_remove(old_regions_removed);
5289 _humongous_set.bulk_remove(humongous_regions_removed);
5290 }
5291
5292 }
5293
5294 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5295 assert(list != NULL, "list can't be null");
5296 if (!list->is_empty()) {
5297 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5298 _hrm.insert_list_into_free_list(list);
5299 }
5300 }
5301
5302 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5303 decrease_used(bytes);
5304 }
5305
5306 class G1ParCleanupCTTask : public AbstractGangTask {
5307 G1SATBCardTableModRefBS* _ct_bs;
5308 G1CollectedHeap* _g1h;
5309 HeapRegion* volatile _su_head;
5310 public:
5311 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5312 G1CollectedHeap* g1h) :
5313 AbstractGangTask("G1 Par Cleanup CT Task"),
5314 _ct_bs(ct_bs), _g1h(g1h) { }
5315
5316 void work(uint worker_id) {
5317 HeapRegion* r;
5318 while (r = _g1h->pop_dirty_cards_region()) {
5319 clear_cards(r);
5320 }
5321 }
5322
5323 void clear_cards(HeapRegion* r) {
5324 // Cards of the survivors should have already been dirtied.
5325 if (!r->is_survivor()) {
5326 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5327 }
5328 }
5329 };
5330
5331 #ifndef PRODUCT
5332 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5333 G1CollectedHeap* _g1h;
5334 G1SATBCardTableModRefBS* _ct_bs;
5335 public:
5336 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5337 : _g1h(g1h), _ct_bs(ct_bs) { }
5338 virtual bool doHeapRegion(HeapRegion* r) {
5339 if (r->is_survivor()) {
5340 _g1h->verify_dirty_region(r);
5341 } else {
5342 _g1h->verify_not_dirty_region(r);
5343 }
5344 return false;
5345 }
5346 };
5347
5348 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5349 // All of the region should be clean.
5350 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5351 MemRegion mr(hr->bottom(), hr->end());
5352 ct_bs->verify_not_dirty_region(mr);
5353 }
5354
5355 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5356 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5357 // dirty allocated blocks as they allocate them. The thread that
5358 // retires each region and replaces it with a new one will do a
5359 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5360 // not dirty that area (one less thing to have to do while holding
5361 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5362 // is dirty.
5363 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5364 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5365 if (hr->is_young()) {
5366 ct_bs->verify_g1_young_region(mr);
5367 } else {
5368 ct_bs->verify_dirty_region(mr);
5369 }
5370 }
5371
5372 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5373 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5374 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5375 verify_dirty_region(hr);
5376 }
5377 }
5378
5379 void G1CollectedHeap::verify_dirty_young_regions() {
5380 verify_dirty_young_list(_young_list->first_region());
5381 }
5382
5383 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5384 HeapWord* tams, HeapWord* end) {
5385 guarantee(tams <= end,
5386 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5387 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5388 if (result < end) {
5389 gclog_or_tty->cr();
5390 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5391 bitmap_name, p2i(result));
5392 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5393 bitmap_name, p2i(tams), p2i(end));
5394 return false;
5395 }
5396 return true;
5397 }
5398
5399 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5400 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5401 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5402
5403 HeapWord* bottom = hr->bottom();
5404 HeapWord* ptams = hr->prev_top_at_mark_start();
5405 HeapWord* ntams = hr->next_top_at_mark_start();
5406 HeapWord* end = hr->end();
5407
5408 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5409
5410 bool res_n = true;
5411 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5412 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5413 // if we happen to be in that state.
5414 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5415 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5416 }
5417 if (!res_p || !res_n) {
5418 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5419 HR_FORMAT_PARAMS(hr));
5420 gclog_or_tty->print_cr("#### Caller: %s", caller);
5421 return false;
5422 }
5423 return true;
5424 }
5425
5426 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5427 if (!G1VerifyBitmaps) return;
5428
5429 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5430 }
5431
5432 class G1VerifyBitmapClosure : public HeapRegionClosure {
5433 private:
5434 const char* _caller;
5435 G1CollectedHeap* _g1h;
5436 bool _failures;
5437
5438 public:
5439 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5440 _caller(caller), _g1h(g1h), _failures(false) { }
5441
5442 bool failures() { return _failures; }
5443
5444 virtual bool doHeapRegion(HeapRegion* hr) {
5445 bool result = _g1h->verify_bitmaps(_caller, hr);
5446 if (!result) {
5447 _failures = true;
5448 }
5449 return false;
5450 }
5451 };
5452
5453 void G1CollectedHeap::check_bitmaps(const char* caller) {
5454 if (!G1VerifyBitmaps) return;
5455
5456 G1VerifyBitmapClosure cl(caller, this);
5457 heap_region_iterate(&cl);
5458 guarantee(!cl.failures(), "bitmap verification");
5459 }
5460
5461 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5462 private:
5463 bool _failures;
5464 public:
5465 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5466
5467 virtual bool doHeapRegion(HeapRegion* hr) {
5468 uint i = hr->hrm_index();
5469 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5470 if (hr->is_humongous()) {
5471 if (hr->in_collection_set()) {
5472 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5473 _failures = true;
5474 return true;
5475 }
5476 if (cset_state.is_in_cset()) {
5477 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5478 _failures = true;
5479 return true;
5480 }
5481 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5482 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5483 _failures = true;
5484 return true;
5485 }
5486 } else {
5487 if (cset_state.is_humongous()) {
5488 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5489 _failures = true;
5490 return true;
5491 }
5492 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5493 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5494 hr->in_collection_set(), cset_state.value(), i);
5495 _failures = true;
5496 return true;
5497 }
5498 if (cset_state.is_in_cset()) {
5499 if (hr->is_young() != (cset_state.is_young())) {
5500 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5501 hr->is_young(), cset_state.value(), i);
5502 _failures = true;
5503 return true;
5504 }
5505 if (hr->is_old() != (cset_state.is_old())) {
5506 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5507 hr->is_old(), cset_state.value(), i);
5508 _failures = true;
5509 return true;
5510 }
5511 }
5512 }
5513 return false;
5514 }
5515
5516 bool failures() const { return _failures; }
5517 };
5518
5519 bool G1CollectedHeap::check_cset_fast_test() {
5520 G1CheckCSetFastTableClosure cl;
5521 _hrm.iterate(&cl);
5522 return !cl.failures();
5523 }
5524 #endif // PRODUCT
5525
5526 void G1CollectedHeap::cleanUpCardTable() {
5527 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5528 double start = os::elapsedTime();
5529
5530 {
5531 // Iterate over the dirty cards region list.
5532 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5533
5534 workers()->run_task(&cleanup_task);
5535 #ifndef PRODUCT
5536 if (G1VerifyCTCleanup || VerifyAfterGC) {
5537 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5538 heap_region_iterate(&cleanup_verifier);
5539 }
5540 #endif
5541 }
5542
5543 double elapsed = os::elapsedTime() - start;
5544 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5545 }
5546
5547 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5548 size_t pre_used = 0;
5549 FreeRegionList local_free_list("Local List for CSet Freeing");
5550
5551 double young_time_ms = 0.0;
5552 double non_young_time_ms = 0.0;
5553
5554 // Since the collection set is a superset of the the young list,
5555 // all we need to do to clear the young list is clear its
5556 // head and length, and unlink any young regions in the code below
5557 _young_list->clear();
5558
5559 G1CollectorPolicy* policy = g1_policy();
5560
5561 double start_sec = os::elapsedTime();
5562 bool non_young = true;
5563
5564 HeapRegion* cur = cs_head;
5565 int age_bound = -1;
5566 size_t rs_lengths = 0;
5567
5568 while (cur != NULL) {
5569 assert(!is_on_master_free_list(cur), "sanity");
5570 if (non_young) {
5571 if (cur->is_young()) {
5572 double end_sec = os::elapsedTime();
5573 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5574 non_young_time_ms += elapsed_ms;
5575
5576 start_sec = os::elapsedTime();
5577 non_young = false;
5578 }
5579 } else {
5580 if (!cur->is_young()) {
5581 double end_sec = os::elapsedTime();
5582 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5583 young_time_ms += elapsed_ms;
5584
5585 start_sec = os::elapsedTime();
5586 non_young = true;
5587 }
5588 }
5589
5590 rs_lengths += cur->rem_set()->occupied_locked();
5591
5592 HeapRegion* next = cur->next_in_collection_set();
5593 assert(cur->in_collection_set(), "bad CS");
5594 cur->set_next_in_collection_set(NULL);
5595 clear_in_cset(cur);
5596
5597 if (cur->is_young()) {
5598 int index = cur->young_index_in_cset();
5599 assert(index != -1, "invariant");
5600 assert((uint) index < policy->young_cset_region_length(), "invariant");
5601 size_t words_survived = surviving_young_words[index];
5602 cur->record_surv_words_in_group(words_survived);
5603
5604 // At this point the we have 'popped' cur from the collection set
5605 // (linked via next_in_collection_set()) but it is still in the
5606 // young list (linked via next_young_region()). Clear the
5607 // _next_young_region field.
5608 cur->set_next_young_region(NULL);
5609 } else {
5610 int index = cur->young_index_in_cset();
5611 assert(index == -1, "invariant");
5612 }
5613
5614 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5615 (!cur->is_young() && cur->young_index_in_cset() == -1),
5616 "invariant" );
5617
5618 if (!cur->evacuation_failed()) {
5619 MemRegion used_mr = cur->used_region();
5620
5621 // And the region is empty.
5622 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5623 pre_used += cur->used();
5624 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5625 } else {
5626 cur->uninstall_surv_rate_group();
5627 if (cur->is_young()) {
5628 cur->set_young_index_in_cset(-1);
5629 }
5630 cur->set_evacuation_failed(false);
5631 // The region is now considered to be old.
5632 cur->set_old();
5633 // Do some allocation statistics accounting. Regions that failed evacuation
5634 // are always made old, so there is no need to update anything in the young
5635 // gen statistics, but we need to update old gen statistics.
5636 size_t used_words = cur->marked_bytes() / HeapWordSize;
5637 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5638 _old_set.add(cur);
5639 evacuation_info.increment_collectionset_used_after(cur->used());
5640 }
5641 cur = next;
5642 }
5643
5644 evacuation_info.set_regions_freed(local_free_list.length());
5645 policy->record_max_rs_lengths(rs_lengths);
5646 policy->cset_regions_freed();
5647
5648 double end_sec = os::elapsedTime();
5649 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5650
5651 if (non_young) {
5652 non_young_time_ms += elapsed_ms;
5653 } else {
5654 young_time_ms += elapsed_ms;
5655 }
5656
5657 prepend_to_freelist(&local_free_list);
5658 decrement_summary_bytes(pre_used);
5659 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5660 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5661 }
5662
5663 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5664 private:
5665 FreeRegionList* _free_region_list;
5666 HeapRegionSet* _proxy_set;
5667 HeapRegionSetCount _humongous_regions_removed;
5668 size_t _freed_bytes;
5669 public:
5670
5671 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5672 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5673 }
5674
5675 virtual bool doHeapRegion(HeapRegion* r) {
5676 if (!r->is_starts_humongous()) {
5677 return false;
5678 }
5679
5680 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5681
5682 oop obj = (oop)r->bottom();
5683 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5684
5685 // The following checks whether the humongous object is live are sufficient.
5686 // The main additional check (in addition to having a reference from the roots
5687 // or the young gen) is whether the humongous object has a remembered set entry.
5688 //
5689 // A humongous object cannot be live if there is no remembered set for it
5690 // because:
5691 // - there can be no references from within humongous starts regions referencing
5692 // the object because we never allocate other objects into them.
5693 // (I.e. there are no intra-region references that may be missed by the
5694 // remembered set)
5695 // - as soon there is a remembered set entry to the humongous starts region
5696 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5697 // until the end of a concurrent mark.
5698 //
5699 // It is not required to check whether the object has been found dead by marking
5700 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5701 // all objects allocated during that time are considered live.
5702 // SATB marking is even more conservative than the remembered set.
5703 // So if at this point in the collection there is no remembered set entry,
5704 // nobody has a reference to it.
5705 // At the start of collection we flush all refinement logs, and remembered sets
5706 // are completely up-to-date wrt to references to the humongous object.
5707 //
5708 // Other implementation considerations:
5709 // - never consider object arrays at this time because they would pose
5710 // considerable effort for cleaning up the the remembered sets. This is
5711 // required because stale remembered sets might reference locations that
5712 // are currently allocated into.
5713 uint region_idx = r->hrm_index();
5714 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5715 !r->rem_set()->is_empty()) {
5716
5717 if (G1TraceEagerReclaimHumongousObjects) {
5718 gclog_or_tty->print_cr("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",
5719 region_idx,
5720 (size_t)obj->size() * HeapWordSize,
5721 p2i(r->bottom()),
5722 r->rem_set()->occupied(),
5723 r->rem_set()->strong_code_roots_list_length(),
5724 next_bitmap->isMarked(r->bottom()),
5725 g1h->is_humongous_reclaim_candidate(region_idx),
5726 obj->is_typeArray()
5727 );
5728 }
5729
5730 return false;
5731 }
5732
5733 guarantee(obj->is_typeArray(),
5734 "Only eagerly reclaiming type arrays is supported, but the object "
5735 PTR_FORMAT " is not.", p2i(r->bottom()));
5736
5737 if (G1TraceEagerReclaimHumongousObjects) {
5738 gclog_or_tty->print_cr("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",
5739 region_idx,
5740 (size_t)obj->size() * HeapWordSize,
5741 p2i(r->bottom()),
5742 r->rem_set()->occupied(),
5743 r->rem_set()->strong_code_roots_list_length(),
5744 next_bitmap->isMarked(r->bottom()),
5745 g1h->is_humongous_reclaim_candidate(region_idx),
5746 obj->is_typeArray()
5747 );
5748 }
5749 // Need to clear mark bit of the humongous object if already set.
5750 if (next_bitmap->isMarked(r->bottom())) {
5751 next_bitmap->clear(r->bottom());
5752 }
5753 do {
5754 HeapRegion* next = g1h->next_region_in_humongous(r);
5755 _freed_bytes += r->used();
5756 r->set_containing_set(NULL);
5757 _humongous_regions_removed.increment(1u, r->capacity());
5758 g1h->free_humongous_region(r, _free_region_list, false);
5759 r = next;
5760 } while (r != NULL);
5761
5762 return false;
5763 }
5764
5765 HeapRegionSetCount& humongous_free_count() {
5766 return _humongous_regions_removed;
5767 }
5768
5769 size_t bytes_freed() const {
5770 return _freed_bytes;
5771 }
5772
5773 size_t humongous_reclaimed() const {
5774 return _humongous_regions_removed.length();
5775 }
5776 };
5777
5778 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5779 assert_at_safepoint(true);
5780
5781 if (!G1EagerReclaimHumongousObjects ||
5782 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5783 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5784 return;
5785 }
5786
5787 double start_time = os::elapsedTime();
5788
5789 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5790
5791 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5792 heap_region_iterate(&cl);
5793
5794 HeapRegionSetCount empty_set;
5795 remove_from_old_sets(empty_set, cl.humongous_free_count());
5796
5797 G1HRPrinter* hrp = hr_printer();
5798 if (hrp->is_active()) {
5799 FreeRegionListIterator iter(&local_cleanup_list);
5800 while (iter.more_available()) {
5801 HeapRegion* hr = iter.get_next();
5802 hrp->cleanup(hr);
5803 }
5804 }
5805
5806 prepend_to_freelist(&local_cleanup_list);
5807 decrement_summary_bytes(cl.bytes_freed());
5808
5809 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5810 cl.humongous_reclaimed());
5811 }
5812
5813 // This routine is similar to the above but does not record
5814 // any policy statistics or update free lists; we are abandoning
5815 // the current incremental collection set in preparation of a
5816 // full collection. After the full GC we will start to build up
5817 // the incremental collection set again.
5818 // This is only called when we're doing a full collection
5819 // and is immediately followed by the tearing down of the young list.
5820
5821 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5822 HeapRegion* cur = cs_head;
5823
5824 while (cur != NULL) {
5825 HeapRegion* next = cur->next_in_collection_set();
5826 assert(cur->in_collection_set(), "bad CS");
5827 cur->set_next_in_collection_set(NULL);
5828 clear_in_cset(cur);
5829 cur->set_young_index_in_cset(-1);
5830 cur = next;
5831 }
5832 }
5833
5834 void G1CollectedHeap::set_free_regions_coming() {
5835 if (G1ConcRegionFreeingVerbose) {
5836 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5837 "setting free regions coming");
5838 }
5839
5840 assert(!free_regions_coming(), "pre-condition");
5841 _free_regions_coming = true;
5842 }
5843
5844 void G1CollectedHeap::reset_free_regions_coming() {
5845 assert(free_regions_coming(), "pre-condition");
5846
5847 {
5848 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5849 _free_regions_coming = false;
5850 SecondaryFreeList_lock->notify_all();
5851 }
5852
5853 if (G1ConcRegionFreeingVerbose) {
5854 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5855 "reset free regions coming");
5856 }
5857 }
5858
5859 void G1CollectedHeap::wait_while_free_regions_coming() {
5860 // Most of the time we won't have to wait, so let's do a quick test
5861 // first before we take the lock.
5862 if (!free_regions_coming()) {
5863 return;
5864 }
5865
5866 if (G1ConcRegionFreeingVerbose) {
5867 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5868 "waiting for free regions");
5869 }
5870
5871 {
5872 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5873 while (free_regions_coming()) {
5874 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5875 }
5876 }
5877
5878 if (G1ConcRegionFreeingVerbose) {
5879 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5880 "done waiting for free regions");
5881 }
5882 }
5883
5884 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5885 return _allocator->is_retained_old_region(hr);
5886 }
5887
5888 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5889 _young_list->push_region(hr);
5890 }
5891
5892 class NoYoungRegionsClosure: public HeapRegionClosure {
5893 private:
5894 bool _success;
5895 public:
5896 NoYoungRegionsClosure() : _success(true) { }
5897 bool doHeapRegion(HeapRegion* r) {
5898 if (r->is_young()) {
5899 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5900 p2i(r->bottom()), p2i(r->end()));
5901 _success = false;
5902 }
5903 return false;
5904 }
5905 bool success() { return _success; }
5906 };
5907
5908 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5909 bool ret = _young_list->check_list_empty(check_sample);
5910
5911 if (check_heap) {
5912 NoYoungRegionsClosure closure;
5913 heap_region_iterate(&closure);
5914 ret = ret && closure.success();
5915 }
5916
5917 return ret;
5918 }
5919
5920 class TearDownRegionSetsClosure : public HeapRegionClosure {
5921 private:
5922 HeapRegionSet *_old_set;
5923
5924 public:
5925 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5926
5927 bool doHeapRegion(HeapRegion* r) {
5928 if (r->is_old()) {
5929 _old_set->remove(r);
5930 } else {
5931 // We ignore free regions, we'll empty the free list afterwards.
5932 // We ignore young regions, we'll empty the young list afterwards.
5933 // We ignore humongous regions, we're not tearing down the
5934 // humongous regions set.
5935 assert(r->is_free() || r->is_young() || r->is_humongous(),
5936 "it cannot be another type");
5937 }
5938 return false;
5939 }
5940
5941 ~TearDownRegionSetsClosure() {
5942 assert(_old_set->is_empty(), "post-condition");
5943 }
5944 };
5945
5946 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5947 assert_at_safepoint(true /* should_be_vm_thread */);
5948
5949 if (!free_list_only) {
5950 TearDownRegionSetsClosure cl(&_old_set);
5951 heap_region_iterate(&cl);
5952
5953 // Note that emptying the _young_list is postponed and instead done as
5954 // the first step when rebuilding the regions sets again. The reason for
5955 // this is that during a full GC string deduplication needs to know if
5956 // a collected region was young or old when the full GC was initiated.
5957 }
5958 _hrm.remove_all_free_regions();
5959 }
5960
5961 void G1CollectedHeap::increase_used(size_t bytes) {
5962 _summary_bytes_used += bytes;
5963 }
5964
5965 void G1CollectedHeap::decrease_used(size_t bytes) {
5966 assert(_summary_bytes_used >= bytes,
5967 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5968 _summary_bytes_used, bytes);
5969 _summary_bytes_used -= bytes;
5970 }
5971
5972 void G1CollectedHeap::set_used(size_t bytes) {
5973 _summary_bytes_used = bytes;
5974 }
5975
5976 class RebuildRegionSetsClosure : public HeapRegionClosure {
5977 private:
5978 bool _free_list_only;
5979 HeapRegionSet* _old_set;
5980 HeapRegionManager* _hrm;
5981 size_t _total_used;
5982
5983 public:
5984 RebuildRegionSetsClosure(bool free_list_only,
5985 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5986 _free_list_only(free_list_only),
5987 _old_set(old_set), _hrm(hrm), _total_used(0) {
5988 assert(_hrm->num_free_regions() == 0, "pre-condition");
5989 if (!free_list_only) {
5990 assert(_old_set->is_empty(), "pre-condition");
5991 }
5992 }
5993
5994 bool doHeapRegion(HeapRegion* r) {
5995 if (r->is_empty()) {
5996 // Add free regions to the free list
5997 r->set_free();
5998 r->set_allocation_context(AllocationContext::system());
5999 _hrm->insert_into_free_list(r);
6000 } else if (!_free_list_only) {
6001 assert(!r->is_young(), "we should not come across young regions");
6002
6003 if (r->is_humongous()) {
6004 // We ignore humongous regions. We left the humongous set unchanged.
6005 } else {
6006 // Objects that were compacted would have ended up on regions
6007 // that were previously old or free. Archive regions (which are
6008 // old) will not have been touched.
6009 assert(r->is_free() || r->is_old(), "invariant");
6010 // We now consider them old, so register as such. Leave
6011 // archive regions set that way, however, while still adding
6012 // them to the old set.
6013 if (!r->is_archive()) {
6014 r->set_old();
6015 }
6016 _old_set->add(r);
6017 }
6018 _total_used += r->used();
6019 }
6020
6021 return false;
6022 }
6023
6024 size_t total_used() {
6025 return _total_used;
6026 }
6027 };
6028
6029 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6030 assert_at_safepoint(true /* should_be_vm_thread */);
6031
6032 if (!free_list_only) {
6033 _young_list->empty_list();
6034 }
6035
6036 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6037 heap_region_iterate(&cl);
6038
6039 if (!free_list_only) {
6040 set_used(cl.total_used());
6041 if (_archive_allocator != NULL) {
6042 _archive_allocator->clear_used();
6043 }
6044 }
6045 assert(used_unlocked() == recalculate_used(),
6046 "inconsistent used_unlocked(), "
6047 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6048 used_unlocked(), recalculate_used());
6049 }
6050
6051 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6052 _refine_cte_cl->set_concurrent(concurrent);
6053 }
6054
6055 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6056 HeapRegion* hr = heap_region_containing(p);
6057 return hr->is_in(p);
6058 }
6059
6060 // Methods for the mutator alloc region
6061
6062 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6063 bool force) {
6064 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6065 assert(!force || g1_policy()->can_expand_young_list(),
6066 "if force is true we should be able to expand the young list");
6067 bool young_list_full = g1_policy()->is_young_list_full();
6068 if (force || !young_list_full) {
6069 HeapRegion* new_alloc_region = new_region(word_size,
6070 false /* is_old */,
6071 false /* do_expand */);
6072 if (new_alloc_region != NULL) {
6073 set_region_short_lived_locked(new_alloc_region);
6074 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6075 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6076 return new_alloc_region;
6077 }
6078 }
6079 return NULL;
6080 }
6081
6082 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6083 size_t allocated_bytes) {
6084 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6085 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6086
6087 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6088 increase_used(allocated_bytes);
6089 _hr_printer.retire(alloc_region);
6090 // We update the eden sizes here, when the region is retired,
6091 // instead of when it's allocated, since this is the point that its
6092 // used space has been recored in _summary_bytes_used.
6093 g1mm()->update_eden_size();
6094 }
6095
6096 // Methods for the GC alloc regions
6097
6098 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6099 uint count,
6100 InCSetState dest) {
6101 assert(FreeList_lock->owned_by_self(), "pre-condition");
6102
6103 if (count < g1_policy()->max_regions(dest)) {
6104 const bool is_survivor = (dest.is_young());
6105 HeapRegion* new_alloc_region = new_region(word_size,
6106 !is_survivor,
6107 true /* do_expand */);
6108 if (new_alloc_region != NULL) {
6109 // We really only need to do this for old regions given that we
6110 // should never scan survivors. But it doesn't hurt to do it
6111 // for survivors too.
6112 new_alloc_region->record_timestamp();
6113 if (is_survivor) {
6114 new_alloc_region->set_survivor();
6115 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6116 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6117 } else {
6118 new_alloc_region->set_old();
6119 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6120 check_bitmaps("Old Region Allocation", new_alloc_region);
6121 }
6122 bool during_im = collector_state()->during_initial_mark_pause();
6123 new_alloc_region->note_start_of_copying(during_im);
6124 return new_alloc_region;
6125 }
6126 }
6127 return NULL;
6128 }
6129
6130 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6131 size_t allocated_bytes,
6132 InCSetState dest) {
6133 bool during_im = collector_state()->during_initial_mark_pause();
6134 alloc_region->note_end_of_copying(during_im);
6135 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6136 if (dest.is_young()) {
6137 young_list()->add_survivor_region(alloc_region);
6138 } else {
6139 _old_set.add(alloc_region);
6140 }
6141 _hr_printer.retire(alloc_region);
6142 }
6143
6144 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6145 bool expanded = false;
6146 uint index = _hrm.find_highest_free(&expanded);
6147
6148 if (index != G1_NO_HRM_INDEX) {
6149 if (expanded) {
6150 ergo_verbose1(ErgoHeapSizing,
6151 "attempt heap expansion",
6152 ergo_format_reason("requested address range outside heap bounds")
6153 ergo_format_byte("region size"),
6154 HeapRegion::GrainWords * HeapWordSize);
6155 }
6156 _hrm.allocate_free_regions_starting_at(index, 1);
6157 return region_at(index);
6158 }
6159 return NULL;
6160 }
6161
6162 // Heap region set verification
6163
6164 class VerifyRegionListsClosure : public HeapRegionClosure {
6165 private:
6166 HeapRegionSet* _old_set;
6167 HeapRegionSet* _humongous_set;
6168 HeapRegionManager* _hrm;
6169
6170 public:
6171 HeapRegionSetCount _old_count;
6172 HeapRegionSetCount _humongous_count;
6173 HeapRegionSetCount _free_count;
6174
6175 VerifyRegionListsClosure(HeapRegionSet* old_set,
6176 HeapRegionSet* humongous_set,
6177 HeapRegionManager* hrm) :
6178 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6179 _old_count(), _humongous_count(), _free_count(){ }
6180
6181 bool doHeapRegion(HeapRegion* hr) {
6182 if (hr->is_young()) {
6183 // TODO
6184 } else if (hr->is_humongous()) {
6185 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6186 _humongous_count.increment(1u, hr->capacity());
6187 } else if (hr->is_empty()) {
6188 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6189 _free_count.increment(1u, hr->capacity());
6190 } else if (hr->is_old()) {
6191 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6192 _old_count.increment(1u, hr->capacity());
6193 } else {
6194 // There are no other valid region types. Check for one invalid
6195 // one we can identify: pinned without old or humongous set.
6196 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6197 ShouldNotReachHere();
6198 }
6199 return false;
6200 }
6201
6202 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6203 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6204 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6205 old_set->total_capacity_bytes(), _old_count.capacity());
6206
6207 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6208 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6209 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6210
6211 guarantee(free_list->num_free_regions() == _free_count.length(), "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length());
6212 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6213 free_list->total_capacity_bytes(), _free_count.capacity());
6214 }
6215 };
6216
6217 void G1CollectedHeap::verify_region_sets() {
6218 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6219
6220 // First, check the explicit lists.
6221 _hrm.verify();
6222 {
6223 // Given that a concurrent operation might be adding regions to
6224 // the secondary free list we have to take the lock before
6225 // verifying it.
6226 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6227 _secondary_free_list.verify_list();
6228 }
6229
6230 // If a concurrent region freeing operation is in progress it will
6231 // be difficult to correctly attributed any free regions we come
6232 // across to the correct free list given that they might belong to
6233 // one of several (free_list, secondary_free_list, any local lists,
6234 // etc.). So, if that's the case we will skip the rest of the
6235 // verification operation. Alternatively, waiting for the concurrent
6236 // operation to complete will have a non-trivial effect on the GC's
6237 // operation (no concurrent operation will last longer than the
6238 // interval between two calls to verification) and it might hide
6239 // any issues that we would like to catch during testing.
6240 if (free_regions_coming()) {
6241 return;
6242 }
6243
6244 // Make sure we append the secondary_free_list on the free_list so
6245 // that all free regions we will come across can be safely
6246 // attributed to the free_list.
6247 append_secondary_free_list_if_not_empty_with_lock();
6248
6249 // Finally, make sure that the region accounting in the lists is
6250 // consistent with what we see in the heap.
6251
6252 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6253 heap_region_iterate(&cl);
6254 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6255 }
6256
6257 // Optimized nmethod scanning
6258
6259 class RegisterNMethodOopClosure: public OopClosure {
6260 G1CollectedHeap* _g1h;
6261 nmethod* _nm;
6262
6263 template <class T> void do_oop_work(T* p) {
6264 T heap_oop = oopDesc::load_heap_oop(p);
6265 if (!oopDesc::is_null(heap_oop)) {
6266 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6267 HeapRegion* hr = _g1h->heap_region_containing(obj);
6268 assert(!hr->is_continues_humongous(),
6269 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6270 " starting at " HR_FORMAT,
6271 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6272
6273 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6274 hr->add_strong_code_root_locked(_nm);
6275 }
6276 }
6277
6278 public:
6279 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6280 _g1h(g1h), _nm(nm) {}
6281
6282 void do_oop(oop* p) { do_oop_work(p); }
6283 void do_oop(narrowOop* p) { do_oop_work(p); }
6284 };
6285
6286 class UnregisterNMethodOopClosure: public OopClosure {
6287 G1CollectedHeap* _g1h;
6288 nmethod* _nm;
6289
6290 template <class T> void do_oop_work(T* p) {
6291 T heap_oop = oopDesc::load_heap_oop(p);
6292 if (!oopDesc::is_null(heap_oop)) {
6293 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6294 HeapRegion* hr = _g1h->heap_region_containing(obj);
6295 assert(!hr->is_continues_humongous(),
6296 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6297 " starting at " HR_FORMAT,
6298 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6299
6300 hr->remove_strong_code_root(_nm);
6301 }
6302 }
6303
6304 public:
6305 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6306 _g1h(g1h), _nm(nm) {}
6307
6308 void do_oop(oop* p) { do_oop_work(p); }
6309 void do_oop(narrowOop* p) { do_oop_work(p); }
6310 };
6311
6312 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6313 CollectedHeap::register_nmethod(nm);
6314
6315 guarantee(nm != NULL, "sanity");
6316 RegisterNMethodOopClosure reg_cl(this, nm);
6317 nm->oops_do(®_cl);
6318 }
6319
6320 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6321 CollectedHeap::unregister_nmethod(nm);
6322
6323 guarantee(nm != NULL, "sanity");
6324 UnregisterNMethodOopClosure reg_cl(this, nm);
6325 nm->oops_do(®_cl, true);
6326 }
6327
6328 void G1CollectedHeap::purge_code_root_memory() {
6329 double purge_start = os::elapsedTime();
6330 G1CodeRootSet::purge();
6331 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6332 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6333 }
6334
6335 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6336 G1CollectedHeap* _g1h;
6337
6338 public:
6339 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6340 _g1h(g1h) {}
6341
6342 void do_code_blob(CodeBlob* cb) {
6343 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6344 if (nm == NULL) {
6345 return;
6346 }
6347
6348 if (ScavengeRootsInCode) {
6349 _g1h->register_nmethod(nm);
6350 }
6351 }
6352 };
6353
6354 void G1CollectedHeap::rebuild_strong_code_roots() {
6355 RebuildStrongCodeRootClosure blob_cl(this);
6356 CodeCache::blobs_do(&blob_cl);
6357 }