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/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootClosures.hpp"
48 #include "gc/g1/g1RootProcessor.hpp"
49 #include "gc/g1/g1StringDedup.hpp"
50 #include "gc/g1/g1YCTypes.hpp"
51 #include "gc/g1/heapRegion.inline.hpp"
52 #include "gc/g1/heapRegionRemSet.hpp"
53 #include "gc/g1/heapRegionSet.inline.hpp"
54 #include "gc/g1/suspendibleThreadSet.hpp"
55 #include "gc/g1/vm_operations_g1.hpp"
56 #include "gc/shared/gcHeapSummary.hpp"
57 #include "gc/shared/gcId.hpp"
58 #include "gc/shared/gcLocker.inline.hpp"
59 #include "gc/shared/gcTimer.hpp"
60 #include "gc/shared/gcTrace.hpp"
61 #include "gc/shared/gcTraceTime.hpp"
62 #include "gc/shared/generationSpec.hpp"
63 #include "gc/shared/isGCActiveMark.hpp"
64 #include "gc/shared/referenceProcessor.hpp"
65 #include "gc/shared/taskqueue.inline.hpp"
66 #include "memory/allocation.hpp"
67 #include "memory/iterator.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/init.hpp"
71 #include "runtime/orderAccess.inline.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "utilities/globalDefinitions.hpp"
74 #include "utilities/stack.inline.hpp"
75
76 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Local to this file.
88
89 class RefineCardTableEntryClosure: public CardTableEntryClosure {
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure() : _concurrent(true) { }
93
94 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
95 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && SuspendibleThreadSet::should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108
109 void set_concurrent(bool b) { _concurrent = b; }
110 };
111
112
113 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
114 private:
115 size_t _num_processed;
116
117 public:
118 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
119
120 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
121 *card_ptr = CardTableModRefBS::dirty_card_val();
122 _num_processed++;
123 return true;
124 }
125
126 size_t num_processed() const { return _num_processed; }
127 };
128
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
141 {
142 // Claim the right to put the region on the dirty cards region list
143 // by installing a self pointer.
144 HeapRegion* next = hr->get_next_dirty_cards_region();
145 if (next == NULL) {
146 HeapRegion* res = (HeapRegion*)
147 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
148 NULL);
149 if (res == NULL) {
150 HeapRegion* head;
151 do {
152 // Put the region to the dirty cards region list.
153 head = _dirty_cards_region_list;
154 next = (HeapRegion*)
155 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
156 if (next == head) {
157 assert(hr->get_next_dirty_cards_region() == hr,
158 "hr->get_next_dirty_cards_region() != hr");
159 if (next == NULL) {
160 // The last region in the list points to itself.
161 hr->set_next_dirty_cards_region(hr);
162 } else {
163 hr->set_next_dirty_cards_region(next);
164 }
165 }
166 } while (next != head);
167 }
168 }
169 }
170
171 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
172 {
173 HeapRegion* head;
174 HeapRegion* hr;
175 do {
176 head = _dirty_cards_region_list;
177 if (head == NULL) {
178 return NULL;
179 }
180 HeapRegion* new_head = head->get_next_dirty_cards_region();
181 if (head == new_head) {
182 // The last region.
183 new_head = NULL;
184 }
185 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
186 head);
187 } while (hr != head);
188 assert(hr != NULL, "invariant");
189 hr->set_next_dirty_cards_region(NULL);
190 return hr;
191 }
192
193 // Returns true if the reference points to an object that
194 // can move in an incremental collection.
195 bool G1CollectedHeap::is_scavengable(const void* p) {
196 HeapRegion* hr = heap_region_containing(p);
197 return !hr->is_pinned();
198 }
199
200 // Private methods.
201
202 HeapRegion*
203 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
205 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
206 if (!_secondary_free_list.is_empty()) {
207 if (G1ConcRegionFreeingVerbose) {
208 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
209 "secondary_free_list has %u entries",
210 _secondary_free_list.length());
211 }
212 // It looks as if there are free regions available on the
213 // secondary_free_list. Let's move them to the free_list and try
214 // again to allocate from it.
215 append_secondary_free_list();
216
217 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
218 "empty we should have moved at least one entry to the free_list");
219 HeapRegion* res = _hrm.allocate_free_region(is_old);
220 if (G1ConcRegionFreeingVerbose) {
221 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
222 "allocated " HR_FORMAT " from secondary_free_list",
223 HR_FORMAT_PARAMS(res));
224 }
225 return res;
226 }
227
228 // Wait here until we get notified either when (a) there are no
229 // more free regions coming or (b) some regions have been moved on
230 // the secondary_free_list.
231 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
232 }
233
234 if (G1ConcRegionFreeingVerbose) {
235 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
236 "could not allocate from secondary_free_list");
237 }
238 return NULL;
239 }
240
241 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
242 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
243 "the only time we use this to allocate a humongous region is "
244 "when we are allocating a single humongous region");
245
246 HeapRegion* res;
247 if (G1StressConcRegionFreeing) {
248 if (!_secondary_free_list.is_empty()) {
249 if (G1ConcRegionFreeingVerbose) {
250 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
251 "forced to look at the secondary_free_list");
252 }
253 res = new_region_try_secondary_free_list(is_old);
254 if (res != NULL) {
255 return res;
256 }
257 }
258 }
259
260 res = _hrm.allocate_free_region(is_old);
261
262 if (res == NULL) {
263 if (G1ConcRegionFreeingVerbose) {
264 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
265 "res == NULL, trying the secondary_free_list");
266 }
267 res = new_region_try_secondary_free_list(is_old);
268 }
269 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
270 // Currently, only attempts to allocate GC alloc regions set
271 // do_expand to true. So, we should only reach here during a
272 // safepoint. If this assumption changes we might have to
273 // reconsider the use of _expand_heap_after_alloc_failure.
274 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
275
276 ergo_verbose1(ErgoHeapSizing,
277 "attempt heap expansion",
278 ergo_format_reason("region allocation request failed")
279 ergo_format_byte("allocation request"),
280 word_size * HeapWordSize);
281 if (expand(word_size * HeapWordSize)) {
282 // Given that expand() succeeded in expanding the heap, and we
283 // always expand the heap by an amount aligned to the heap
284 // region size, the free list should in theory not be empty.
285 // In either case allocate_free_region() will check for NULL.
286 res = _hrm.allocate_free_region(is_old);
287 } else {
288 _expand_heap_after_alloc_failure = false;
289 }
290 }
291 return res;
292 }
293
294 HeapWord*
295 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
296 uint num_regions,
297 size_t word_size,
298 AllocationContext_t context) {
299 assert(first != G1_NO_HRM_INDEX, "pre-condition");
300 assert(is_humongous(word_size), "word_size should be humongous");
301 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
302
303 // Index of last region in the series + 1.
304 uint last = first + num_regions;
305
306 // We need to initialize the region(s) we just discovered. This is
307 // a bit tricky given that it can happen concurrently with
308 // refinement threads refining cards on these regions and
309 // potentially wanting to refine the BOT as they are scanning
310 // those cards (this can happen shortly after a cleanup; see CR
311 // 6991377). So we have to set up the region(s) carefully and in
312 // a specific order.
313
314 // The word size sum of all the regions we will allocate.
315 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
316 assert(word_size <= word_size_sum, "sanity");
317
318 // This will be the "starts humongous" region.
319 HeapRegion* first_hr = region_at(first);
320 // The header of the new object will be placed at the bottom of
321 // the first region.
322 HeapWord* new_obj = first_hr->bottom();
323 // This will be the new top of the new object.
324 HeapWord* obj_top = new_obj + word_size;
325
326 // First, we need to zero the header of the space that we will be
327 // allocating. When we update top further down, some refinement
328 // threads might try to scan the region. By zeroing the header we
329 // ensure that any thread that will try to scan the region will
330 // come across the zero klass word and bail out.
331 //
332 // NOTE: It would not have been correct to have used
333 // CollectedHeap::fill_with_object() and make the space look like
334 // an int array. The thread that is doing the allocation will
335 // later update the object header to a potentially different array
336 // type and, for a very short period of time, the klass and length
337 // fields will be inconsistent. This could cause a refinement
338 // thread to calculate the object size incorrectly.
339 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
340
341 // We will set up the first region as "starts humongous". This
342 // will also update the BOT covering all the regions to reflect
343 // that there is a single object that starts at the bottom of the
344 // first region.
345 first_hr->set_starts_humongous(obj_top);
346 first_hr->set_allocation_context(context);
347 // Then, if there are any, we will set up the "continues
348 // humongous" regions.
349 HeapRegion* hr = NULL;
350 for (uint i = first + 1; i < last; ++i) {
351 hr = region_at(i);
352 hr->set_continues_humongous(first_hr);
353 hr->set_allocation_context(context);
354 }
355
356 // Up to this point no concurrent thread would have been able to
357 // do any scanning on any region in this series. All the top
358 // fields still point to bottom, so the intersection between
359 // [bottom,top] and [card_start,card_end] will be empty. Before we
360 // update the top fields, we'll do a storestore to make sure that
361 // no thread sees the update to top before the zeroing of the
362 // object header and the BOT initialization.
363 OrderAccess::storestore();
364
365 // Now that the BOT and the object header have been initialized,
366 // we can update top of the "starts humongous" region.
367 first_hr->set_top(MIN2(first_hr->end(), obj_top));
368 if (_hr_printer.is_active()) {
369 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->top());
370 }
371
372 // Now, we will update the top fields of the "continues humongous"
373 // regions.
374 hr = NULL;
375 for (uint i = first + 1; i < last; ++i) {
376 hr = region_at(i);
377 if ((i + 1) == last) {
378 // last continues humongous region
379 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
380 "new_top should fall on this region");
381 hr->set_top(obj_top);
382 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
383 } else {
384 // not last one
385 assert(obj_top > hr->end(), "obj_top should be above this region");
386 hr->set_top(hr->end());
387 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
388 }
389 }
390 // If we have continues humongous regions (hr != NULL), its top should
391 // match obj_top.
392 assert(hr == NULL || (hr->top() == obj_top), "sanity");
393 check_bitmaps("Humongous Region Allocation", first_hr);
394
395 increase_used(word_size * HeapWordSize);
396
397 for (uint i = first; i < last; ++i) {
398 _humongous_set.add(region_at(i));
399 }
400
401 return new_obj;
402 }
403
404 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
405 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
406 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
407 }
408
409 // If could fit into free regions w/o expansion, try.
410 // Otherwise, if can expand, do so.
411 // Otherwise, if using ex regions might help, try with ex given back.
412 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
413 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
414
415 verify_region_sets_optional();
416
417 uint first = G1_NO_HRM_INDEX;
418 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
419
420 if (obj_regions == 1) {
421 // Only one region to allocate, try to use a fast path by directly allocating
422 // from the free lists. Do not try to expand here, we will potentially do that
423 // later.
424 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
425 if (hr != NULL) {
426 first = hr->hrm_index();
427 }
428 } else {
429 // We can't allocate humongous regions spanning more than one region while
430 // cleanupComplete() is running, since some of the regions we find to be
431 // empty might not yet be added to the free list. It is not straightforward
432 // to know in which list they are on so that we can remove them. We only
433 // need to do this if we need to allocate more than one region to satisfy the
434 // current humongous allocation request. If we are only allocating one region
435 // we use the one-region region allocation code (see above), that already
436 // potentially waits for regions from the secondary free list.
437 wait_while_free_regions_coming();
438 append_secondary_free_list_if_not_empty_with_lock();
439
440 // Policy: Try only empty regions (i.e. already committed first). Maybe we
441 // are lucky enough to find some.
442 first = _hrm.find_contiguous_only_empty(obj_regions);
443 if (first != G1_NO_HRM_INDEX) {
444 _hrm.allocate_free_regions_starting_at(first, obj_regions);
445 }
446 }
447
448 if (first == G1_NO_HRM_INDEX) {
449 // Policy: We could not find enough regions for the humongous object in the
450 // free list. Look through the heap to find a mix of free and uncommitted regions.
451 // If so, try expansion.
452 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
453 if (first != G1_NO_HRM_INDEX) {
454 // We found something. Make sure these regions are committed, i.e. expand
455 // the heap. Alternatively we could do a defragmentation GC.
456 ergo_verbose1(ErgoHeapSizing,
457 "attempt heap expansion",
458 ergo_format_reason("humongous allocation request failed")
459 ergo_format_byte("allocation request"),
460 word_size * HeapWordSize);
461
462 _hrm.expand_at(first, obj_regions);
463 g1_policy()->record_new_heap_size(num_regions());
464
465 #ifdef ASSERT
466 for (uint i = first; i < first + obj_regions; ++i) {
467 HeapRegion* hr = region_at(i);
468 assert(hr->is_free(), "sanity");
469 assert(hr->is_empty(), "sanity");
470 assert(is_on_master_free_list(hr), "sanity");
471 }
472 #endif
473 _hrm.allocate_free_regions_starting_at(first, obj_regions);
474 } else {
475 // Policy: Potentially trigger a defragmentation GC.
476 }
477 }
478
479 HeapWord* result = NULL;
480 if (first != G1_NO_HRM_INDEX) {
481 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
482 word_size, context);
483 assert(result != NULL, "it should always return a valid result");
484
485 // A successful humongous object allocation changes the used space
486 // information of the old generation so we need to recalculate the
487 // sizes and update the jstat counters here.
488 g1mm()->update_sizes();
489 }
490
491 verify_region_sets_optional();
492
493 return result;
494 }
495
496 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
497 assert_heap_not_locked_and_not_at_safepoint();
498 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
499
500 uint dummy_gc_count_before;
501 uint dummy_gclocker_retry_count = 0;
502 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
503 }
504
505 HeapWord*
506 G1CollectedHeap::mem_allocate(size_t word_size,
507 bool* gc_overhead_limit_was_exceeded) {
508 assert_heap_not_locked_and_not_at_safepoint();
509
510 // Loop until the allocation is satisfied, or unsatisfied after GC.
511 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
512 uint gc_count_before;
513
514 HeapWord* result = NULL;
515 if (!is_humongous(word_size)) {
516 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
517 } else {
518 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
519 }
520 if (result != NULL) {
521 return result;
522 }
523
524 // Create the garbage collection operation...
525 VM_G1CollectForAllocation op(gc_count_before, word_size);
526 op.set_allocation_context(AllocationContext::current());
527
528 // ...and get the VM thread to execute it.
529 VMThread::execute(&op);
530
531 if (op.prologue_succeeded() && op.pause_succeeded()) {
532 // If the operation was successful we'll return the result even
533 // if it is NULL. If the allocation attempt failed immediately
534 // after a Full GC, it's unlikely we'll be able to allocate now.
535 HeapWord* result = op.result();
536 if (result != NULL && !is_humongous(word_size)) {
537 // Allocations that take place on VM operations do not do any
538 // card dirtying and we have to do it here. We only have to do
539 // this for non-humongous allocations, though.
540 dirty_young_block(result, word_size);
541 }
542 return result;
543 } else {
544 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
545 return NULL;
546 }
547 assert(op.result() == NULL,
548 "the result should be NULL if the VM op did not succeed");
549 }
550
551 // Give a warning if we seem to be looping forever.
552 if ((QueuedAllocationWarningCount > 0) &&
553 (try_count % QueuedAllocationWarningCount == 0)) {
554 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
555 }
556 }
557
558 ShouldNotReachHere();
559 return NULL;
560 }
561
562 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
563 AllocationContext_t context,
564 uint* gc_count_before_ret,
565 uint* gclocker_retry_count_ret) {
566 // Make sure you read the note in attempt_allocation_humongous().
567
568 assert_heap_not_locked_and_not_at_safepoint();
569 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
570 "be called for humongous allocation requests");
571
572 // We should only get here after the first-level allocation attempt
573 // (attempt_allocation()) failed to allocate.
574
575 // We will loop until a) we manage to successfully perform the
576 // allocation or b) we successfully schedule a collection which
577 // fails to perform the allocation. b) is the only case when we'll
578 // return NULL.
579 HeapWord* result = NULL;
580 for (int try_count = 1; /* we'll return */; try_count += 1) {
581 bool should_try_gc;
582 uint gc_count_before;
583
584 {
585 MutexLockerEx x(Heap_lock);
586 result = _allocator->attempt_allocation_locked(word_size, context);
587 if (result != NULL) {
588 return result;
589 }
590
591 if (GC_locker::is_active_and_needs_gc()) {
592 if (g1_policy()->can_expand_young_list()) {
593 // No need for an ergo verbose message here,
594 // can_expand_young_list() does this when it returns true.
595 result = _allocator->attempt_allocation_force(word_size, context);
596 if (result != NULL) {
597 return result;
598 }
599 }
600 should_try_gc = false;
601 } else {
602 // The GCLocker may not be active but the GCLocker initiated
603 // GC may not yet have been performed (GCLocker::needs_gc()
604 // returns true). In this case we do not try this GC and
605 // wait until the GCLocker initiated GC is performed, and
606 // then retry the allocation.
607 if (GC_locker::needs_gc()) {
608 should_try_gc = false;
609 } else {
610 // Read the GC count while still holding the Heap_lock.
611 gc_count_before = total_collections();
612 should_try_gc = true;
613 }
614 }
615 }
616
617 if (should_try_gc) {
618 bool succeeded;
619 result = do_collection_pause(word_size, gc_count_before, &succeeded,
620 GCCause::_g1_inc_collection_pause);
621 if (result != NULL) {
622 assert(succeeded, "only way to get back a non-NULL result");
623 return result;
624 }
625
626 if (succeeded) {
627 // If we get here we successfully scheduled a collection which
628 // failed to allocate. No point in trying to allocate
629 // further. We'll just return NULL.
630 MutexLockerEx x(Heap_lock);
631 *gc_count_before_ret = total_collections();
632 return NULL;
633 }
634 } else {
635 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
636 MutexLockerEx x(Heap_lock);
637 *gc_count_before_ret = total_collections();
638 return NULL;
639 }
640 // The GCLocker is either active or the GCLocker initiated
641 // GC has not yet been performed. Stall until it is and
642 // then retry the allocation.
643 GC_locker::stall_until_clear();
644 (*gclocker_retry_count_ret) += 1;
645 }
646
647 // We can reach here if we were unsuccessful in scheduling a
648 // collection (because another thread beat us to it) or if we were
649 // stalled due to the GC locker. In either can we should retry the
650 // allocation attempt in case another thread successfully
651 // performed a collection and reclaimed enough space. We do the
652 // first attempt (without holding the Heap_lock) here and the
653 // follow-on attempt will be at the start of the next loop
654 // iteration (after taking the Heap_lock).
655 result = _allocator->attempt_allocation(word_size, context);
656 if (result != NULL) {
657 return result;
658 }
659
660 // Give a warning if we seem to be looping forever.
661 if ((QueuedAllocationWarningCount > 0) &&
662 (try_count % QueuedAllocationWarningCount == 0)) {
663 warning("G1CollectedHeap::attempt_allocation_slow() "
664 "retries %d times", try_count);
665 }
666 }
667
668 ShouldNotReachHere();
669 return NULL;
670 }
671
672 void G1CollectedHeap::begin_archive_alloc_range() {
673 assert_at_safepoint(true /* should_be_vm_thread */);
674 if (_archive_allocator == NULL) {
675 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
676 }
677 }
678
679 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
680 // Allocations in archive regions cannot be of a size that would be considered
681 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
682 // may be different at archive-restore time.
683 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
684 }
685
686 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
687 assert_at_safepoint(true /* should_be_vm_thread */);
688 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
689 if (is_archive_alloc_too_large(word_size)) {
690 return NULL;
691 }
692 return _archive_allocator->archive_mem_allocate(word_size);
693 }
694
695 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
696 size_t end_alignment_in_bytes) {
697 assert_at_safepoint(true /* should_be_vm_thread */);
698 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
699
700 // Call complete_archive to do the real work, filling in the MemRegion
701 // array with the archive regions.
702 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
703 delete _archive_allocator;
704 _archive_allocator = NULL;
705 }
706
707 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
708 assert(ranges != NULL, "MemRegion array NULL");
709 assert(count != 0, "No MemRegions provided");
710 MemRegion reserved = _hrm.reserved();
711 for (size_t i = 0; i < count; i++) {
712 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
713 return false;
714 }
715 }
716 return true;
717 }
718
719 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
720 assert(!is_init_completed(), "Expect to be called at JVM init time");
721 assert(ranges != NULL, "MemRegion array NULL");
722 assert(count != 0, "No MemRegions provided");
723 MutexLockerEx x(Heap_lock);
724
725 MemRegion reserved = _hrm.reserved();
726 HeapWord* prev_last_addr = NULL;
727 HeapRegion* prev_last_region = NULL;
728
729 // Temporarily disable pretouching of heap pages. This interface is used
730 // when mmap'ing archived heap data in, so pre-touching is wasted.
731 FlagSetting fs(AlwaysPreTouch, false);
732
733 // Enable archive object checking in G1MarkSweep. We have to let it know
734 // about each archive range, so that objects in those ranges aren't marked.
735 G1MarkSweep::enable_archive_object_check();
736
737 // For each specified MemRegion range, allocate the corresponding G1
738 // regions and mark them as archive regions. We expect the ranges in
739 // ascending starting address order, without overlap.
740 for (size_t i = 0; i < count; i++) {
741 MemRegion curr_range = ranges[i];
742 HeapWord* start_address = curr_range.start();
743 size_t word_size = curr_range.word_size();
744 HeapWord* last_address = curr_range.last();
745 size_t commits = 0;
746
747 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
748 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
749 p2i(start_address), p2i(last_address));
750 guarantee(start_address > prev_last_addr,
751 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
752 p2i(start_address), p2i(prev_last_addr));
753 prev_last_addr = last_address;
754
755 // Check for ranges that start in the same G1 region in which the previous
756 // range ended, and adjust the start address so we don't try to allocate
757 // the same region again. If the current range is entirely within that
758 // region, skip it, just adjusting the recorded top.
759 HeapRegion* start_region = _hrm.addr_to_region(start_address);
760 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
761 start_address = start_region->end();
762 if (start_address > last_address) {
763 increase_used(word_size * HeapWordSize);
764 start_region->set_top(last_address + 1);
765 continue;
766 }
767 start_region->set_top(start_address);
768 curr_range = MemRegion(start_address, last_address + 1);
769 start_region = _hrm.addr_to_region(start_address);
770 }
771
772 // Perform the actual region allocation, exiting if it fails.
773 // Then note how much new space we have allocated.
774 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
775 return false;
776 }
777 increase_used(word_size * HeapWordSize);
778 if (commits != 0) {
779 ergo_verbose1(ErgoHeapSizing,
780 "attempt heap expansion",
781 ergo_format_reason("allocate archive regions")
782 ergo_format_byte("total size"),
783 HeapRegion::GrainWords * HeapWordSize * commits);
784 }
785
786 // Mark each G1 region touched by the range as archive, add it to the old set,
787 // and set the allocation context and top.
788 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
789 HeapRegion* last_region = _hrm.addr_to_region(last_address);
790 prev_last_region = last_region;
791
792 while (curr_region != NULL) {
793 assert(curr_region->is_empty() && !curr_region->is_pinned(),
794 "Region already in use (index %u)", curr_region->hrm_index());
795 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
796 curr_region->set_allocation_context(AllocationContext::system());
797 curr_region->set_archive();
798 _old_set.add(curr_region);
799 if (curr_region != last_region) {
800 curr_region->set_top(curr_region->end());
801 curr_region = _hrm.next_region_in_heap(curr_region);
802 } else {
803 curr_region->set_top(last_address + 1);
804 curr_region = NULL;
805 }
806 }
807
808 // Notify mark-sweep of the archive range.
809 G1MarkSweep::set_range_archive(curr_range, true);
810 }
811 return true;
812 }
813
814 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
815 assert(!is_init_completed(), "Expect to be called at JVM init time");
816 assert(ranges != NULL, "MemRegion array NULL");
817 assert(count != 0, "No MemRegions provided");
818 MemRegion reserved = _hrm.reserved();
819 HeapWord *prev_last_addr = NULL;
820 HeapRegion* prev_last_region = NULL;
821
822 // For each MemRegion, create filler objects, if needed, in the G1 regions
823 // that contain the address range. The address range actually within the
824 // MemRegion will not be modified. That is assumed to have been initialized
825 // elsewhere, probably via an mmap of archived heap data.
826 MutexLockerEx x(Heap_lock);
827 for (size_t i = 0; i < count; i++) {
828 HeapWord* start_address = ranges[i].start();
829 HeapWord* last_address = ranges[i].last();
830
831 assert(reserved.contains(start_address) && reserved.contains(last_address),
832 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
833 p2i(start_address), p2i(last_address));
834 assert(start_address > prev_last_addr,
835 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
836 p2i(start_address), p2i(prev_last_addr));
837
838 HeapRegion* start_region = _hrm.addr_to_region(start_address);
839 HeapRegion* last_region = _hrm.addr_to_region(last_address);
840 HeapWord* bottom_address = start_region->bottom();
841
842 // Check for a range beginning in the same region in which the
843 // previous one ended.
844 if (start_region == prev_last_region) {
845 bottom_address = prev_last_addr + 1;
846 }
847
848 // Verify that the regions were all marked as archive regions by
849 // alloc_archive_regions.
850 HeapRegion* curr_region = start_region;
851 while (curr_region != NULL) {
852 guarantee(curr_region->is_archive(),
853 "Expected archive region at index %u", curr_region->hrm_index());
854 if (curr_region != last_region) {
855 curr_region = _hrm.next_region_in_heap(curr_region);
856 } else {
857 curr_region = NULL;
858 }
859 }
860
861 prev_last_addr = last_address;
862 prev_last_region = last_region;
863
864 // Fill the memory below the allocated range with dummy object(s),
865 // if the region bottom does not match the range start, or if the previous
866 // range ended within the same G1 region, and there is a gap.
867 if (start_address != bottom_address) {
868 size_t fill_size = pointer_delta(start_address, bottom_address);
869 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
870 increase_used(fill_size * HeapWordSize);
871 }
872 }
873 }
874
875 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
876 uint* gc_count_before_ret,
877 uint* gclocker_retry_count_ret) {
878 assert_heap_not_locked_and_not_at_safepoint();
879 assert(!is_humongous(word_size), "attempt_allocation() should not "
880 "be called for humongous allocation requests");
881
882 AllocationContext_t context = AllocationContext::current();
883 HeapWord* result = _allocator->attempt_allocation(word_size, context);
884
885 if (result == NULL) {
886 result = attempt_allocation_slow(word_size,
887 context,
888 gc_count_before_ret,
889 gclocker_retry_count_ret);
890 }
891 assert_heap_not_locked();
892 if (result != NULL) {
893 dirty_young_block(result, word_size);
894 }
895 return result;
896 }
897
898 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
899 assert(!is_init_completed(), "Expect to be called at JVM init time");
900 assert(ranges != NULL, "MemRegion array NULL");
901 assert(count != 0, "No MemRegions provided");
902 MemRegion reserved = _hrm.reserved();
903 HeapWord* prev_last_addr = NULL;
904 HeapRegion* prev_last_region = NULL;
905 size_t size_used = 0;
906 size_t uncommitted_regions = 0;
907
908 // For each Memregion, free the G1 regions that constitute it, and
909 // notify mark-sweep that the range is no longer to be considered 'archive.'
910 MutexLockerEx x(Heap_lock);
911 for (size_t i = 0; i < count; i++) {
912 HeapWord* start_address = ranges[i].start();
913 HeapWord* last_address = ranges[i].last();
914
915 assert(reserved.contains(start_address) && reserved.contains(last_address),
916 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
917 p2i(start_address), p2i(last_address));
918 assert(start_address > prev_last_addr,
919 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
920 p2i(start_address), p2i(prev_last_addr));
921 size_used += ranges[i].byte_size();
922 prev_last_addr = last_address;
923
924 HeapRegion* start_region = _hrm.addr_to_region(start_address);
925 HeapRegion* last_region = _hrm.addr_to_region(last_address);
926
927 // Check for ranges that start in the same G1 region in which the previous
928 // range ended, and adjust the start address so we don't try to free
929 // the same region again. If the current range is entirely within that
930 // region, skip it.
931 if (start_region == prev_last_region) {
932 start_address = start_region->end();
933 if (start_address > last_address) {
934 continue;
935 }
936 start_region = _hrm.addr_to_region(start_address);
937 }
938 prev_last_region = last_region;
939
940 // After verifying that each region was marked as an archive region by
941 // alloc_archive_regions, set it free and empty and uncommit it.
942 HeapRegion* curr_region = start_region;
943 while (curr_region != NULL) {
944 guarantee(curr_region->is_archive(),
945 "Expected archive region at index %u", curr_region->hrm_index());
946 uint curr_index = curr_region->hrm_index();
947 _old_set.remove(curr_region);
948 curr_region->set_free();
949 curr_region->set_top(curr_region->bottom());
950 if (curr_region != last_region) {
951 curr_region = _hrm.next_region_in_heap(curr_region);
952 } else {
953 curr_region = NULL;
954 }
955 _hrm.shrink_at(curr_index, 1);
956 uncommitted_regions++;
957 }
958
959 // Notify mark-sweep that this is no longer an archive range.
960 G1MarkSweep::set_range_archive(ranges[i], false);
961 }
962
963 if (uncommitted_regions != 0) {
964 ergo_verbose1(ErgoHeapSizing,
965 "attempt heap shrinking",
966 ergo_format_reason("uncommitted archive regions")
967 ergo_format_byte("total size"),
968 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
969 }
970 decrease_used(size_used);
971 }
972
973 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
974 uint* gc_count_before_ret,
975 uint* gclocker_retry_count_ret) {
976 // The structure of this method has a lot of similarities to
977 // attempt_allocation_slow(). The reason these two were not merged
978 // into a single one is that such a method would require several "if
979 // allocation is not humongous do this, otherwise do that"
980 // conditional paths which would obscure its flow. In fact, an early
981 // version of this code did use a unified method which was harder to
982 // follow and, as a result, it had subtle bugs that were hard to
983 // track down. So keeping these two methods separate allows each to
984 // be more readable. It will be good to keep these two in sync as
985 // much as possible.
986
987 assert_heap_not_locked_and_not_at_safepoint();
988 assert(is_humongous(word_size), "attempt_allocation_humongous() "
989 "should only be called for humongous allocations");
990
991 // Humongous objects can exhaust the heap quickly, so we should check if we
992 // need to start a marking cycle at each humongous object allocation. We do
993 // the check before we do the actual allocation. The reason for doing it
994 // before the allocation is that we avoid having to keep track of the newly
995 // allocated memory while we do a GC.
996 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
997 word_size)) {
998 collect(GCCause::_g1_humongous_allocation);
999 }
1000
1001 // We will loop until a) we manage to successfully perform the
1002 // allocation or b) we successfully schedule a collection which
1003 // fails to perform the allocation. b) is the only case when we'll
1004 // return NULL.
1005 HeapWord* result = NULL;
1006 for (int try_count = 1; /* we'll return */; try_count += 1) {
1007 bool should_try_gc;
1008 uint gc_count_before;
1009
1010 {
1011 MutexLockerEx x(Heap_lock);
1012
1013 // Given that humongous objects are not allocated in young
1014 // regions, we'll first try to do the allocation without doing a
1015 // collection hoping that there's enough space in the heap.
1016 result = humongous_obj_allocate(word_size, AllocationContext::current());
1017 if (result != NULL) {
1018 g1_policy()->add_last_old_allocated_bytes(humongous_obj_size_in_regions(word_size) * HeapRegion::GrainBytes);
1019 return result;
1020 }
1021
1022 if (GC_locker::is_active_and_needs_gc()) {
1023 should_try_gc = false;
1024 } else {
1025 // The GCLocker may not be active but the GCLocker initiated
1026 // GC may not yet have been performed (GCLocker::needs_gc()
1027 // returns true). In this case we do not try this GC and
1028 // wait until the GCLocker initiated GC is performed, and
1029 // then retry the allocation.
1030 if (GC_locker::needs_gc()) {
1031 should_try_gc = false;
1032 } else {
1033 // Read the GC count while still holding the Heap_lock.
1034 gc_count_before = total_collections();
1035 should_try_gc = true;
1036 }
1037 }
1038 }
1039
1040 if (should_try_gc) {
1041 // If we failed to allocate the humongous object, we should try to
1042 // do a collection pause (if we're allowed) in case it reclaims
1043 // enough space for the allocation to succeed after the pause.
1044
1045 bool succeeded;
1046 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1047 GCCause::_g1_humongous_allocation);
1048 if (result != NULL) {
1049 assert(succeeded, "only way to get back a non-NULL result");
1050 return result;
1051 }
1052
1053 if (succeeded) {
1054 // If we get here we successfully scheduled a collection which
1055 // failed to allocate. No point in trying to allocate
1056 // further. We'll just return NULL.
1057 MutexLockerEx x(Heap_lock);
1058 *gc_count_before_ret = total_collections();
1059 return NULL;
1060 }
1061 } else {
1062 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1063 MutexLockerEx x(Heap_lock);
1064 *gc_count_before_ret = total_collections();
1065 return NULL;
1066 }
1067 // The GCLocker is either active or the GCLocker initiated
1068 // GC has not yet been performed. Stall until it is and
1069 // then retry the allocation.
1070 GC_locker::stall_until_clear();
1071 (*gclocker_retry_count_ret) += 1;
1072 }
1073
1074 // We can reach here if we were unsuccessful in scheduling a
1075 // collection (because another thread beat us to it) or if we were
1076 // stalled due to the GC locker. In either can we should retry the
1077 // allocation attempt in case another thread successfully
1078 // performed a collection and reclaimed enough space. Give a
1079 // warning if we seem to be looping forever.
1080
1081 if ((QueuedAllocationWarningCount > 0) &&
1082 (try_count % QueuedAllocationWarningCount == 0)) {
1083 warning("G1CollectedHeap::attempt_allocation_humongous() "
1084 "retries %d times", try_count);
1085 }
1086 }
1087
1088 ShouldNotReachHere();
1089 return NULL;
1090 }
1091
1092 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1093 AllocationContext_t context,
1094 bool expect_null_mutator_alloc_region) {
1095 assert_at_safepoint(true /* should_be_vm_thread */);
1096 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1097 "the current alloc region was unexpectedly found to be non-NULL");
1098
1099 if (!is_humongous(word_size)) {
1100 return _allocator->attempt_allocation_locked(word_size, context);
1101 } else {
1102 HeapWord* result = humongous_obj_allocate(word_size, context);
1103 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1104 collector_state()->set_initiate_conc_mark_if_possible(true);
1105 }
1106 return result;
1107 }
1108
1109 ShouldNotReachHere();
1110 }
1111
1112 class PostMCRemSetClearClosure: public HeapRegionClosure {
1113 G1CollectedHeap* _g1h;
1114 ModRefBarrierSet* _mr_bs;
1115 public:
1116 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1117 _g1h(g1h), _mr_bs(mr_bs) {}
1118
1119 bool doHeapRegion(HeapRegion* r) {
1120 HeapRegionRemSet* hrrs = r->rem_set();
1121
1122 _g1h->reset_gc_time_stamps(r);
1123
1124 if (r->is_continues_humongous()) {
1125 // We'll assert that the strong code root list and RSet is empty
1126 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1127 assert(hrrs->occupied() == 0, "RSet should be empty");
1128 } else {
1129 hrrs->clear();
1130 }
1131 // You might think here that we could clear just the cards
1132 // corresponding to the used region. But no: if we leave a dirty card
1133 // in a region we might allocate into, then it would prevent that card
1134 // from being enqueued, and cause it to be missed.
1135 // Re: the performance cost: we shouldn't be doing full GC anyway!
1136 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1137
1138 return false;
1139 }
1140 };
1141
1142 void G1CollectedHeap::clear_rsets_post_compaction() {
1143 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1144 heap_region_iterate(&rs_clear);
1145 }
1146
1147 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1148 G1CollectedHeap* _g1h;
1149 UpdateRSOopClosure _cl;
1150 public:
1151 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1152 _cl(g1->g1_rem_set(), worker_i),
1153 _g1h(g1)
1154 { }
1155
1156 bool doHeapRegion(HeapRegion* r) {
1157 if (!r->is_continues_humongous()) {
1158 _cl.set_from(r);
1159 r->oop_iterate(&_cl);
1160 }
1161 return false;
1162 }
1163 };
1164
1165 class ParRebuildRSTask: public AbstractGangTask {
1166 G1CollectedHeap* _g1;
1167 HeapRegionClaimer _hrclaimer;
1168
1169 public:
1170 ParRebuildRSTask(G1CollectedHeap* g1) :
1171 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1172
1173 void work(uint worker_id) {
1174 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1175 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1176 }
1177 };
1178
1179 class PostCompactionPrinterClosure: public HeapRegionClosure {
1180 private:
1181 G1HRPrinter* _hr_printer;
1182 public:
1183 bool doHeapRegion(HeapRegion* hr) {
1184 assert(!hr->is_young(), "not expecting to find young regions");
1185 if (hr->is_free()) {
1186 // We only generate output for non-empty regions.
1187 } else if (hr->is_starts_humongous()) {
1188 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1189 } else if (hr->is_continues_humongous()) {
1190 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1191 } else if (hr->is_archive()) {
1192 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1193 } else if (hr->is_old()) {
1194 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1195 } else {
1196 ShouldNotReachHere();
1197 }
1198 return false;
1199 }
1200
1201 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1202 : _hr_printer(hr_printer) { }
1203 };
1204
1205 void G1CollectedHeap::print_hrm_post_compaction() {
1206 PostCompactionPrinterClosure cl(hr_printer());
1207 heap_region_iterate(&cl);
1208 }
1209
1210 bool G1CollectedHeap::do_collection(bool explicit_gc,
1211 bool clear_all_soft_refs,
1212 size_t word_size) {
1213 assert_at_safepoint(true /* should_be_vm_thread */);
1214
1215 if (GC_locker::check_active_before_gc()) {
1216 return false;
1217 }
1218
1219 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1220 gc_timer->register_gc_start();
1221
1222 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1223 GCIdMark gc_id_mark;
1224 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1225
1226 SvcGCMarker sgcm(SvcGCMarker::FULL);
1227 ResourceMark rm;
1228
1229 G1Log::update_level();
1230 print_heap_before_gc();
1231 trace_heap_before_gc(gc_tracer);
1232
1233 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1234
1235 verify_region_sets_optional();
1236
1237 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1238 collector_policy()->should_clear_all_soft_refs();
1239
1240 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1241
1242 {
1243 IsGCActiveMark x;
1244
1245 // Timing
1246 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1247 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1248
1249 {
1250 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1251 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1252 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1253
1254 g1_policy()->record_full_collection_start();
1255
1256 // Note: When we have a more flexible GC logging framework that
1257 // allows us to add optional attributes to a GC log record we
1258 // could consider timing and reporting how long we wait in the
1259 // following two methods.
1260 wait_while_free_regions_coming();
1261 // If we start the compaction before the CM threads finish
1262 // scanning the root regions we might trip them over as we'll
1263 // be moving objects / updating references. So let's wait until
1264 // they are done. By telling them to abort, they should complete
1265 // early.
1266 _cm->root_regions()->abort();
1267 _cm->root_regions()->wait_until_scan_finished();
1268 append_secondary_free_list_if_not_empty_with_lock();
1269
1270 gc_prologue(true);
1271 increment_total_collections(true /* full gc */);
1272 increment_old_marking_cycles_started();
1273
1274 assert(used() == recalculate_used(), "Should be equal");
1275
1276 verify_before_gc();
1277
1278 check_bitmaps("Full GC Start");
1279 pre_full_gc_dump(gc_timer);
1280
1281 #if defined(COMPILER2) || INCLUDE_JVMCI
1282 DerivedPointerTable::clear();
1283 #endif
1284
1285 // Disable discovery and empty the discovered lists
1286 // for the CM ref processor.
1287 ref_processor_cm()->disable_discovery();
1288 ref_processor_cm()->abandon_partial_discovery();
1289 ref_processor_cm()->verify_no_references_recorded();
1290
1291 // Abandon current iterations of concurrent marking and concurrent
1292 // refinement, if any are in progress. We have to do this before
1293 // wait_until_scan_finished() below.
1294 concurrent_mark()->abort();
1295
1296 // Make sure we'll choose a new allocation region afterwards.
1297 _allocator->release_mutator_alloc_region();
1298 _allocator->abandon_gc_alloc_regions();
1299 g1_rem_set()->cleanupHRRS();
1300
1301 // We should call this after we retire any currently active alloc
1302 // regions so that all the ALLOC / RETIRE events are generated
1303 // before the start GC event.
1304 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1305
1306 // We may have added regions to the current incremental collection
1307 // set between the last GC or pause and now. We need to clear the
1308 // incremental collection set and then start rebuilding it afresh
1309 // after this full GC.
1310 abandon_collection_set(g1_policy()->inc_cset_head());
1311 g1_policy()->clear_incremental_cset();
1312 g1_policy()->stop_incremental_cset_building();
1313
1314 tear_down_region_sets(false /* free_list_only */);
1315 collector_state()->set_gcs_are_young(true);
1316
1317 // See the comments in g1CollectedHeap.hpp and
1318 // G1CollectedHeap::ref_processing_init() about
1319 // how reference processing currently works in G1.
1320
1321 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1322 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1323
1324 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1325 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1326
1327 ref_processor_stw()->enable_discovery();
1328 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1329
1330 // Do collection work
1331 {
1332 HandleMark hm; // Discard invalid handles created during gc
1333 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1334 }
1335
1336 assert(num_free_regions() == 0, "we should not have added any free regions");
1337 rebuild_region_sets(false /* free_list_only */);
1338
1339 // Enqueue any discovered reference objects that have
1340 // not been removed from the discovered lists.
1341 ref_processor_stw()->enqueue_discovered_references();
1342
1343 #if defined(COMPILER2) || INCLUDE_JVMCI
1344 DerivedPointerTable::update_pointers();
1345 #endif
1346
1347 MemoryService::track_memory_usage();
1348
1349 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1350 ref_processor_stw()->verify_no_references_recorded();
1351
1352 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1353 ClassLoaderDataGraph::purge();
1354 MetaspaceAux::verify_metrics();
1355
1356 // Note: since we've just done a full GC, concurrent
1357 // marking is no longer active. Therefore we need not
1358 // re-enable reference discovery for the CM ref processor.
1359 // That will be done at the start of the next marking cycle.
1360 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1361 ref_processor_cm()->verify_no_references_recorded();
1362
1363 reset_gc_time_stamp();
1364 // Since everything potentially moved, we will clear all remembered
1365 // sets, and clear all cards. Later we will rebuild remembered
1366 // sets. We will also reset the GC time stamps of the regions.
1367 clear_rsets_post_compaction();
1368 check_gc_time_stamps();
1369
1370 // Resize the heap if necessary.
1371 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1372
1373 if (_hr_printer.is_active()) {
1374 // We should do this after we potentially resize the heap so
1375 // that all the COMMIT / UNCOMMIT events are generated before
1376 // the end GC event.
1377
1378 print_hrm_post_compaction();
1379 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1380 }
1381
1382 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1383 if (hot_card_cache->use_cache()) {
1384 hot_card_cache->reset_card_counts();
1385 hot_card_cache->reset_hot_cache();
1386 }
1387
1388 // Rebuild remembered sets of all regions.
1389 uint n_workers =
1390 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1391 workers()->active_workers(),
1392 Threads::number_of_non_daemon_threads());
1393 workers()->set_active_workers(n_workers);
1394
1395 ParRebuildRSTask rebuild_rs_task(this);
1396 workers()->run_task(&rebuild_rs_task);
1397
1398 // Rebuild the strong code root lists for each region
1399 rebuild_strong_code_roots();
1400
1401 if (true) { // FIXME
1402 MetaspaceGC::compute_new_size();
1403 }
1404
1405 #ifdef TRACESPINNING
1406 ParallelTaskTerminator::print_termination_counts();
1407 #endif
1408
1409 // Discard all rset updates
1410 JavaThread::dirty_card_queue_set().abandon_logs();
1411 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1412
1413 _young_list->reset_sampled_info();
1414 // At this point there should be no regions in the
1415 // entire heap tagged as young.
1416 assert(check_young_list_empty(true /* check_heap */),
1417 "young list should be empty at this point");
1418
1419 // Update the number of full collections that have been completed.
1420 increment_old_marking_cycles_completed(false /* concurrent */);
1421
1422 _hrm.verify_optional();
1423 verify_region_sets_optional();
1424
1425 verify_after_gc();
1426
1427 // Clear the previous marking bitmap, if needed for bitmap verification.
1428 // Note we cannot do this when we clear the next marking bitmap in
1429 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1430 // objects marked during a full GC against the previous bitmap.
1431 // But we need to clear it before calling check_bitmaps below since
1432 // the full GC has compacted objects and updated TAMS but not updated
1433 // the prev bitmap.
1434 if (G1VerifyBitmaps) {
1435 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1436 }
1437 check_bitmaps("Full GC End");
1438
1439 // Start a new incremental collection set for the next pause
1440 assert(g1_policy()->collection_set() == NULL, "must be");
1441 g1_policy()->start_incremental_cset_building();
1442
1443 clear_cset_fast_test();
1444
1445 _allocator->init_mutator_alloc_region();
1446
1447 g1_policy()->record_full_collection_end();
1448
1449 if (G1Log::fine()) {
1450 g1_policy()->print_heap_transition();
1451 }
1452
1453 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1454 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1455 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1456 // before any GC notifications are raised.
1457 g1mm()->update_sizes();
1458
1459 gc_epilogue(true);
1460 }
1461
1462 if (G1Log::finer()) {
1463 g1_policy()->print_detailed_heap_transition(true /* full */);
1464 }
1465
1466 print_heap_after_gc();
1467 trace_heap_after_gc(gc_tracer);
1468
1469 post_full_gc_dump(gc_timer);
1470
1471 gc_timer->register_gc_end();
1472 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1473 }
1474
1475 return true;
1476 }
1477
1478 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1479 // do_collection() will return whether it succeeded in performing
1480 // the GC. Currently, there is no facility on the
1481 // do_full_collection() API to notify the caller than the collection
1482 // did not succeed (e.g., because it was locked out by the GC
1483 // locker). So, right now, we'll ignore the return value.
1484 bool dummy = do_collection(true, /* explicit_gc */
1485 clear_all_soft_refs,
1486 0 /* word_size */);
1487 }
1488
1489 // This code is mostly copied from TenuredGeneration.
1490 void
1491 G1CollectedHeap::
1492 resize_if_necessary_after_full_collection(size_t word_size) {
1493 // Include the current allocation, if any, and bytes that will be
1494 // pre-allocated to support collections, as "used".
1495 const size_t used_after_gc = used();
1496 const size_t capacity_after_gc = capacity();
1497 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1498
1499 // This is enforced in arguments.cpp.
1500 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1501 "otherwise the code below doesn't make sense");
1502
1503 // We don't have floating point command-line arguments
1504 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1505 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1506 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1507 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1508
1509 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1510 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1511
1512 // We have to be careful here as these two calculations can overflow
1513 // 32-bit size_t's.
1514 double used_after_gc_d = (double) used_after_gc;
1515 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1516 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1517
1518 // Let's make sure that they are both under the max heap size, which
1519 // by default will make them fit into a size_t.
1520 double desired_capacity_upper_bound = (double) max_heap_size;
1521 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1522 desired_capacity_upper_bound);
1523 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1524 desired_capacity_upper_bound);
1525
1526 // We can now safely turn them into size_t's.
1527 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1528 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1529
1530 // This assert only makes sense here, before we adjust them
1531 // with respect to the min and max heap size.
1532 assert(minimum_desired_capacity <= maximum_desired_capacity,
1533 "minimum_desired_capacity = " SIZE_FORMAT ", "
1534 "maximum_desired_capacity = " SIZE_FORMAT,
1535 minimum_desired_capacity, maximum_desired_capacity);
1536
1537 // Should not be greater than the heap max size. No need to adjust
1538 // it with respect to the heap min size as it's a lower bound (i.e.,
1539 // we'll try to make the capacity larger than it, not smaller).
1540 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1541 // Should not be less than the heap min size. No need to adjust it
1542 // with respect to the heap max size as it's an upper bound (i.e.,
1543 // we'll try to make the capacity smaller than it, not greater).
1544 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1545
1546 if (capacity_after_gc < minimum_desired_capacity) {
1547 // Don't expand unless it's significant
1548 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1549 ergo_verbose4(ErgoHeapSizing,
1550 "attempt heap expansion",
1551 ergo_format_reason("capacity lower than "
1552 "min desired capacity after Full GC")
1553 ergo_format_byte("capacity")
1554 ergo_format_byte("occupancy")
1555 ergo_format_byte_perc("min desired capacity"),
1556 capacity_after_gc, used_after_gc,
1557 minimum_desired_capacity, (double) MinHeapFreeRatio);
1558 expand(expand_bytes);
1559
1560 // No expansion, now see if we want to shrink
1561 } else if (capacity_after_gc > maximum_desired_capacity) {
1562 // Capacity too large, compute shrinking size
1563 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1564 ergo_verbose4(ErgoHeapSizing,
1565 "attempt heap shrinking",
1566 ergo_format_reason("capacity higher than "
1567 "max desired capacity after Full GC")
1568 ergo_format_byte("capacity")
1569 ergo_format_byte("occupancy")
1570 ergo_format_byte_perc("max desired capacity"),
1571 capacity_after_gc, used_after_gc,
1572 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1573 shrink(shrink_bytes);
1574 }
1575 }
1576
1577 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1578 AllocationContext_t context,
1579 bool do_gc,
1580 bool clear_all_soft_refs,
1581 bool expect_null_mutator_alloc_region,
1582 bool* gc_succeeded) {
1583 *gc_succeeded = true;
1584 // Let's attempt the allocation first.
1585 HeapWord* result =
1586 attempt_allocation_at_safepoint(word_size,
1587 context,
1588 expect_null_mutator_alloc_region);
1589 if (result != NULL) {
1590 assert(*gc_succeeded, "sanity");
1591 return result;
1592 }
1593
1594 // In a G1 heap, we're supposed to keep allocation from failing by
1595 // incremental pauses. Therefore, at least for now, we'll favor
1596 // expansion over collection. (This might change in the future if we can
1597 // do something smarter than full collection to satisfy a failed alloc.)
1598 result = expand_and_allocate(word_size, context);
1599 if (result != NULL) {
1600 assert(*gc_succeeded, "sanity");
1601 return result;
1602 }
1603
1604 if (do_gc) {
1605 // Expansion didn't work, we'll try to do a Full GC.
1606 *gc_succeeded = do_collection(false, /* explicit_gc */
1607 clear_all_soft_refs,
1608 word_size);
1609 }
1610
1611 return NULL;
1612 }
1613
1614 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1615 AllocationContext_t context,
1616 bool* succeeded) {
1617 assert_at_safepoint(true /* should_be_vm_thread */);
1618
1619 // Attempts to allocate followed by Full GC.
1620 HeapWord* result =
1621 satisfy_failed_allocation_helper(word_size,
1622 context,
1623 true, /* do_gc */
1624 false, /* clear_all_soft_refs */
1625 false, /* expect_null_mutator_alloc_region */
1626 succeeded);
1627
1628 if (result != NULL || !*succeeded) {
1629 return result;
1630 }
1631
1632 // Attempts to allocate followed by Full GC that will collect all soft references.
1633 result = satisfy_failed_allocation_helper(word_size,
1634 context,
1635 true, /* do_gc */
1636 true, /* clear_all_soft_refs */
1637 true, /* expect_null_mutator_alloc_region */
1638 succeeded);
1639
1640 if (result != NULL || !*succeeded) {
1641 return result;
1642 }
1643
1644 // Attempts to allocate, no GC
1645 result = satisfy_failed_allocation_helper(word_size,
1646 context,
1647 false, /* do_gc */
1648 false, /* clear_all_soft_refs */
1649 true, /* expect_null_mutator_alloc_region */
1650 succeeded);
1651
1652 if (result != NULL) {
1653 assert(*succeeded, "sanity");
1654 return result;
1655 }
1656
1657 assert(!collector_policy()->should_clear_all_soft_refs(),
1658 "Flag should have been handled and cleared prior to this point");
1659
1660 // What else? We might try synchronous finalization later. If the total
1661 // space available is large enough for the allocation, then a more
1662 // complete compaction phase than we've tried so far might be
1663 // appropriate.
1664 assert(*succeeded, "sanity");
1665 return NULL;
1666 }
1667
1668 // Attempting to expand the heap sufficiently
1669 // to support an allocation of the given "word_size". If
1670 // successful, perform the allocation and return the address of the
1671 // allocated block, or else "NULL".
1672
1673 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1674 assert_at_safepoint(true /* should_be_vm_thread */);
1675
1676 verify_region_sets_optional();
1677
1678 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1679 ergo_verbose1(ErgoHeapSizing,
1680 "attempt heap expansion",
1681 ergo_format_reason("allocation request failed")
1682 ergo_format_byte("allocation request"),
1683 word_size * HeapWordSize);
1684 if (expand(expand_bytes)) {
1685 _hrm.verify_optional();
1686 verify_region_sets_optional();
1687 return attempt_allocation_at_safepoint(word_size,
1688 context,
1689 false /* expect_null_mutator_alloc_region */);
1690 }
1691 return NULL;
1692 }
1693
1694 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1695 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1696 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1697 HeapRegion::GrainBytes);
1698 ergo_verbose2(ErgoHeapSizing,
1699 "expand the heap",
1700 ergo_format_byte("requested expansion amount")
1701 ergo_format_byte("attempted expansion amount"),
1702 expand_bytes, aligned_expand_bytes);
1703
1704 if (is_maximal_no_gc()) {
1705 ergo_verbose0(ErgoHeapSizing,
1706 "did not expand the heap",
1707 ergo_format_reason("heap already fully expanded"));
1708 return false;
1709 }
1710
1711 double expand_heap_start_time_sec = os::elapsedTime();
1712 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1713 assert(regions_to_expand > 0, "Must expand by at least one region");
1714
1715 uint expanded_by = _hrm.expand_by(regions_to_expand);
1716 if (expand_time_ms != NULL) {
1717 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1718 }
1719
1720 if (expanded_by > 0) {
1721 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1722 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1723 g1_policy()->record_new_heap_size(num_regions());
1724 } else {
1725 ergo_verbose0(ErgoHeapSizing,
1726 "did not expand the heap",
1727 ergo_format_reason("heap expansion operation failed"));
1728 // The expansion of the virtual storage space was unsuccessful.
1729 // Let's see if it was because we ran out of swap.
1730 if (G1ExitOnExpansionFailure &&
1731 _hrm.available() >= regions_to_expand) {
1732 // We had head room...
1733 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1734 }
1735 }
1736 return regions_to_expand > 0;
1737 }
1738
1739 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1740 size_t aligned_shrink_bytes =
1741 ReservedSpace::page_align_size_down(shrink_bytes);
1742 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1743 HeapRegion::GrainBytes);
1744 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1745
1746 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1747 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1748
1749 ergo_verbose3(ErgoHeapSizing,
1750 "shrink the heap",
1751 ergo_format_byte("requested shrinking amount")
1752 ergo_format_byte("aligned shrinking amount")
1753 ergo_format_byte("attempted shrinking amount"),
1754 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1755 if (num_regions_removed > 0) {
1756 g1_policy()->record_new_heap_size(num_regions());
1757 } else {
1758 ergo_verbose0(ErgoHeapSizing,
1759 "did not shrink the heap",
1760 ergo_format_reason("heap shrinking operation failed"));
1761 }
1762 }
1763
1764 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1765 verify_region_sets_optional();
1766
1767 // We should only reach here at the end of a Full GC which means we
1768 // should not not be holding to any GC alloc regions. The method
1769 // below will make sure of that and do any remaining clean up.
1770 _allocator->abandon_gc_alloc_regions();
1771
1772 // Instead of tearing down / rebuilding the free lists here, we
1773 // could instead use the remove_all_pending() method on free_list to
1774 // remove only the ones that we need to remove.
1775 tear_down_region_sets(true /* free_list_only */);
1776 shrink_helper(shrink_bytes);
1777 rebuild_region_sets(true /* free_list_only */);
1778
1779 _hrm.verify_optional();
1780 verify_region_sets_optional();
1781 }
1782
1783 // Public methods.
1784
1785 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1786 CollectedHeap(),
1787 _g1_policy(policy_),
1788 _dirty_card_queue_set(false),
1789 _is_alive_closure_cm(this),
1790 _is_alive_closure_stw(this),
1791 _ref_processor_cm(NULL),
1792 _ref_processor_stw(NULL),
1793 _bot_shared(NULL),
1794 _cg1r(NULL),
1795 _g1mm(NULL),
1796 _refine_cte_cl(NULL),
1797 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1798 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1799 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1800 _humongous_reclaim_candidates(),
1801 _has_humongous_reclaim_candidates(false),
1802 _archive_allocator(NULL),
1803 _free_regions_coming(false),
1804 _young_list(new YoungList(this)),
1805 _gc_time_stamp(0),
1806 _summary_bytes_used(0),
1807 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1808 _old_evac_stats(OldPLABSize, PLABWeight),
1809 _expand_heap_after_alloc_failure(true),
1810 _old_marking_cycles_started(0),
1811 _old_marking_cycles_completed(0),
1812 _heap_summary_sent(false),
1813 _in_cset_fast_test(),
1814 _dirty_cards_region_list(NULL),
1815 _worker_cset_start_region(NULL),
1816 _worker_cset_start_region_time_stamp(NULL),
1817 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1818 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1819 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1820 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1821
1822 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1823 /* are_GC_task_threads */true,
1824 /* are_ConcurrentGC_threads */false);
1825 _workers->initialize_workers();
1826
1827 _allocator = G1Allocator::create_allocator(this);
1828 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1829
1830 // Override the default _filler_array_max_size so that no humongous filler
1831 // objects are created.
1832 _filler_array_max_size = _humongous_object_threshold_in_words;
1833
1834 uint n_queues = ParallelGCThreads;
1835 _task_queues = new RefToScanQueueSet(n_queues);
1836
1837 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1838 assert(n_rem_sets > 0, "Invariant.");
1839
1840 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1841 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1842 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1843
1844 for (uint i = 0; i < n_queues; i++) {
1845 RefToScanQueue* q = new RefToScanQueue();
1846 q->initialize();
1847 _task_queues->register_queue(i, q);
1848 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1849 }
1850 clear_cset_start_regions();
1851
1852 // Initialize the G1EvacuationFailureALot counters and flags.
1853 NOT_PRODUCT(reset_evacuation_should_fail();)
1854
1855 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1856 }
1857
1858 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1859 size_t size,
1860 size_t translation_factor) {
1861 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1862 // Allocate a new reserved space, preferring to use large pages.
1863 ReservedSpace rs(size, preferred_page_size);
1864 G1RegionToSpaceMapper* result =
1865 G1RegionToSpaceMapper::create_mapper(rs,
1866 size,
1867 rs.alignment(),
1868 HeapRegion::GrainBytes,
1869 translation_factor,
1870 mtGC);
1871 if (TracePageSizes) {
1872 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1873 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1874 }
1875 return result;
1876 }
1877
1878 jint G1CollectedHeap::initialize() {
1879 CollectedHeap::pre_initialize();
1880 os::enable_vtime();
1881
1882 G1Log::init();
1883
1884 // Necessary to satisfy locking discipline assertions.
1885
1886 MutexLocker x(Heap_lock);
1887
1888 // We have to initialize the printer before committing the heap, as
1889 // it will be used then.
1890 _hr_printer.set_active(G1PrintHeapRegions);
1891
1892 // While there are no constraints in the GC code that HeapWordSize
1893 // be any particular value, there are multiple other areas in the
1894 // system which believe this to be true (e.g. oop->object_size in some
1895 // cases incorrectly returns the size in wordSize units rather than
1896 // HeapWordSize).
1897 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1898
1899 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1900 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1901 size_t heap_alignment = collector_policy()->heap_alignment();
1902
1903 // Ensure that the sizes are properly aligned.
1904 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1905 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1906 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1907
1908 _refine_cte_cl = new RefineCardTableEntryClosure();
1909
1910 jint ecode = JNI_OK;
1911 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1912 if (_cg1r == NULL) {
1913 return ecode;
1914 }
1915
1916 // Reserve the maximum.
1917
1918 // When compressed oops are enabled, the preferred heap base
1919 // is calculated by subtracting the requested size from the
1920 // 32Gb boundary and using the result as the base address for
1921 // heap reservation. If the requested size is not aligned to
1922 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1923 // into the ReservedHeapSpace constructor) then the actual
1924 // base of the reserved heap may end up differing from the
1925 // address that was requested (i.e. the preferred heap base).
1926 // If this happens then we could end up using a non-optimal
1927 // compressed oops mode.
1928
1929 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1930 heap_alignment);
1931
1932 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1933
1934 // Create the barrier set for the entire reserved region.
1935 G1SATBCardTableLoggingModRefBS* bs
1936 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1937 bs->initialize();
1938 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1939 set_barrier_set(bs);
1940
1941 // Also create a G1 rem set.
1942 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1943
1944 // Carve out the G1 part of the heap.
1945
1946 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1947 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1948 G1RegionToSpaceMapper* heap_storage =
1949 G1RegionToSpaceMapper::create_mapper(g1_rs,
1950 g1_rs.size(),
1951 page_size,
1952 HeapRegion::GrainBytes,
1953 1,
1954 mtJavaHeap);
1955 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1956 max_byte_size, page_size,
1957 heap_rs.base(),
1958 heap_rs.size());
1959 heap_storage->set_mapping_changed_listener(&_listener);
1960
1961 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1962 G1RegionToSpaceMapper* bot_storage =
1963 create_aux_memory_mapper("Block offset table",
1964 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1965 G1BlockOffsetSharedArray::heap_map_factor());
1966
1967 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1968 G1RegionToSpaceMapper* cardtable_storage =
1969 create_aux_memory_mapper("Card table",
1970 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1971 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1972
1973 G1RegionToSpaceMapper* card_counts_storage =
1974 create_aux_memory_mapper("Card counts table",
1975 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1976 G1CardCounts::heap_map_factor());
1977
1978 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1979 G1RegionToSpaceMapper* prev_bitmap_storage =
1980 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1981 G1RegionToSpaceMapper* next_bitmap_storage =
1982 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1983
1984 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1985 g1_barrier_set()->initialize(cardtable_storage);
1986 // Do later initialization work for concurrent refinement.
1987 _cg1r->init(card_counts_storage);
1988
1989 // 6843694 - ensure that the maximum region index can fit
1990 // in the remembered set structures.
1991 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1992 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1993
1994 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1995 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1996 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1997 "too many cards per region");
1998
1999 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2000
2001 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2002
2003 {
2004 HeapWord* start = _hrm.reserved().start();
2005 HeapWord* end = _hrm.reserved().end();
2006 size_t granularity = HeapRegion::GrainBytes;
2007
2008 _in_cset_fast_test.initialize(start, end, granularity);
2009 _humongous_reclaim_candidates.initialize(start, end, granularity);
2010 }
2011
2012 // Create the ConcurrentMark data structure and thread.
2013 // (Must do this late, so that "max_regions" is defined.)
2014 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2015 if (_cm == NULL || !_cm->completed_initialization()) {
2016 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2017 return JNI_ENOMEM;
2018 }
2019 _cmThread = _cm->cmThread();
2020
2021 // Initialize the from_card cache structure of HeapRegionRemSet.
2022 HeapRegionRemSet::init_heap(max_regions());
2023
2024 // Now expand into the initial heap size.
2025 if (!expand(init_byte_size)) {
2026 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2027 return JNI_ENOMEM;
2028 }
2029
2030 // Perform any initialization actions delegated to the policy.
2031 g1_policy()->init();
2032
2033 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2034 SATB_Q_FL_lock,
2035 G1SATBProcessCompletedThreshold,
2036 Shared_SATB_Q_lock);
2037
2038 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2039 DirtyCardQ_CBL_mon,
2040 DirtyCardQ_FL_lock,
2041 concurrent_g1_refine()->yellow_zone(),
2042 concurrent_g1_refine()->red_zone(),
2043 Shared_DirtyCardQ_lock);
2044
2045 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2046 DirtyCardQ_CBL_mon,
2047 DirtyCardQ_FL_lock,
2048 -1, // never trigger processing
2049 -1, // no limit on length
2050 Shared_DirtyCardQ_lock,
2051 &JavaThread::dirty_card_queue_set());
2052
2053 // Here we allocate the dummy HeapRegion that is required by the
2054 // G1AllocRegion class.
2055 HeapRegion* dummy_region = _hrm.get_dummy_region();
2056
2057 // We'll re-use the same region whether the alloc region will
2058 // require BOT updates or not and, if it doesn't, then a non-young
2059 // region will complain that it cannot support allocations without
2060 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2061 dummy_region->set_eden();
2062 // Make sure it's full.
2063 dummy_region->set_top(dummy_region->end());
2064 G1AllocRegion::setup(this, dummy_region);
2065
2066 _allocator->init_mutator_alloc_region();
2067
2068 // Do create of the monitoring and management support so that
2069 // values in the heap have been properly initialized.
2070 _g1mm = new G1MonitoringSupport(this);
2071
2072 G1StringDedup::initialize();
2073
2074 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2075 for (uint i = 0; i < ParallelGCThreads; i++) {
2076 new (&_preserved_objs[i]) OopAndMarkOopStack();
2077 }
2078
2079 return JNI_OK;
2080 }
2081
2082 void G1CollectedHeap::stop() {
2083 // Stop all concurrent threads. We do this to make sure these threads
2084 // do not continue to execute and access resources (e.g. gclog_or_tty)
2085 // that are destroyed during shutdown.
2086 _cg1r->stop();
2087 _cmThread->stop();
2088 if (G1StringDedup::is_enabled()) {
2089 G1StringDedup::stop();
2090 }
2091 }
2092
2093 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2094 return HeapRegion::max_region_size();
2095 }
2096
2097 void G1CollectedHeap::post_initialize() {
2098 CollectedHeap::post_initialize();
2099 ref_processing_init();
2100 }
2101
2102 void G1CollectedHeap::ref_processing_init() {
2103 // Reference processing in G1 currently works as follows:
2104 //
2105 // * There are two reference processor instances. One is
2106 // used to record and process discovered references
2107 // during concurrent marking; the other is used to
2108 // record and process references during STW pauses
2109 // (both full and incremental).
2110 // * Both ref processors need to 'span' the entire heap as
2111 // the regions in the collection set may be dotted around.
2112 //
2113 // * For the concurrent marking ref processor:
2114 // * Reference discovery is enabled at initial marking.
2115 // * Reference discovery is disabled and the discovered
2116 // references processed etc during remarking.
2117 // * Reference discovery is MT (see below).
2118 // * Reference discovery requires a barrier (see below).
2119 // * Reference processing may or may not be MT
2120 // (depending on the value of ParallelRefProcEnabled
2121 // and ParallelGCThreads).
2122 // * A full GC disables reference discovery by the CM
2123 // ref processor and abandons any entries on it's
2124 // discovered lists.
2125 //
2126 // * For the STW processor:
2127 // * Non MT discovery is enabled at the start of a full GC.
2128 // * Processing and enqueueing during a full GC is non-MT.
2129 // * During a full GC, references are processed after marking.
2130 //
2131 // * Discovery (may or may not be MT) is enabled at the start
2132 // of an incremental evacuation pause.
2133 // * References are processed near the end of a STW evacuation pause.
2134 // * For both types of GC:
2135 // * Discovery is atomic - i.e. not concurrent.
2136 // * Reference discovery will not need a barrier.
2137
2138 MemRegion mr = reserved_region();
2139
2140 // Concurrent Mark ref processor
2141 _ref_processor_cm =
2142 new ReferenceProcessor(mr, // span
2143 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2144 // mt processing
2145 ParallelGCThreads,
2146 // degree of mt processing
2147 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2148 // mt discovery
2149 MAX2(ParallelGCThreads, ConcGCThreads),
2150 // degree of mt discovery
2151 false,
2152 // Reference discovery is not atomic
2153 &_is_alive_closure_cm);
2154 // is alive closure
2155 // (for efficiency/performance)
2156
2157 // STW ref processor
2158 _ref_processor_stw =
2159 new ReferenceProcessor(mr, // span
2160 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2161 // mt processing
2162 ParallelGCThreads,
2163 // degree of mt processing
2164 (ParallelGCThreads > 1),
2165 // mt discovery
2166 ParallelGCThreads,
2167 // degree of mt discovery
2168 true,
2169 // Reference discovery is atomic
2170 &_is_alive_closure_stw);
2171 // is alive closure
2172 // (for efficiency/performance)
2173 }
2174
2175 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2176 return g1_policy();
2177 }
2178
2179 size_t G1CollectedHeap::capacity() const {
2180 return _hrm.length() * HeapRegion::GrainBytes;
2181 }
2182
2183 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2184 hr->reset_gc_time_stamp();
2185 }
2186
2187 #ifndef PRODUCT
2188
2189 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2190 private:
2191 unsigned _gc_time_stamp;
2192 bool _failures;
2193
2194 public:
2195 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2196 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2197
2198 virtual bool doHeapRegion(HeapRegion* hr) {
2199 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2200 if (_gc_time_stamp != region_gc_time_stamp) {
2201 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2202 "expected %d", HR_FORMAT_PARAMS(hr),
2203 region_gc_time_stamp, _gc_time_stamp);
2204 _failures = true;
2205 }
2206 return false;
2207 }
2208
2209 bool failures() { return _failures; }
2210 };
2211
2212 void G1CollectedHeap::check_gc_time_stamps() {
2213 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2214 heap_region_iterate(&cl);
2215 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2216 }
2217 #endif // PRODUCT
2218
2219 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2220 _cg1r->hot_card_cache()->drain(cl, worker_i);
2221 }
2222
2223 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2224 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2225 size_t n_completed_buffers = 0;
2226 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2227 n_completed_buffers++;
2228 }
2229 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2230 dcqs.clear_n_completed_buffers();
2231 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2232 }
2233
2234 // Computes the sum of the storage used by the various regions.
2235 size_t G1CollectedHeap::used() const {
2236 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2237 if (_archive_allocator != NULL) {
2238 result += _archive_allocator->used();
2239 }
2240 return result;
2241 }
2242
2243 size_t G1CollectedHeap::used_unlocked() const {
2244 return _summary_bytes_used;
2245 }
2246
2247 class SumUsedClosure: public HeapRegionClosure {
2248 size_t _used;
2249 public:
2250 SumUsedClosure() : _used(0) {}
2251 bool doHeapRegion(HeapRegion* r) {
2252 _used += r->used();
2253 return false;
2254 }
2255 size_t result() { return _used; }
2256 };
2257
2258 size_t G1CollectedHeap::recalculate_used() const {
2259 double recalculate_used_start = os::elapsedTime();
2260
2261 SumUsedClosure blk;
2262 heap_region_iterate(&blk);
2263
2264 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2265 return blk.result();
2266 }
2267
2268 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2269 switch (cause) {
2270 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2271 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2272 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2273 case GCCause::_g1_humongous_allocation: return true;
2274 case GCCause::_update_allocation_context_stats_inc: return true;
2275 case GCCause::_wb_conc_mark: return true;
2276 default: return false;
2277 }
2278 }
2279
2280 #ifndef PRODUCT
2281 void G1CollectedHeap::allocate_dummy_regions() {
2282 // Let's fill up most of the region
2283 size_t word_size = HeapRegion::GrainWords - 1024;
2284 // And as a result the region we'll allocate will be humongous.
2285 guarantee(is_humongous(word_size), "sanity");
2286
2287 // _filler_array_max_size is set to humongous object threshold
2288 // but temporarily change it to use CollectedHeap::fill_with_object().
2289 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2290
2291 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2292 // Let's use the existing mechanism for the allocation
2293 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2294 AllocationContext::system());
2295 if (dummy_obj != NULL) {
2296 MemRegion mr(dummy_obj, word_size);
2297 CollectedHeap::fill_with_object(mr);
2298 } else {
2299 // If we can't allocate once, we probably cannot allocate
2300 // again. Let's get out of the loop.
2301 break;
2302 }
2303 }
2304 }
2305 #endif // !PRODUCT
2306
2307 void G1CollectedHeap::increment_old_marking_cycles_started() {
2308 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2309 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2310 "Wrong marking cycle count (started: %d, completed: %d)",
2311 _old_marking_cycles_started, _old_marking_cycles_completed);
2312
2313 _old_marking_cycles_started++;
2314 }
2315
2316 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2317 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2318
2319 // We assume that if concurrent == true, then the caller is a
2320 // concurrent thread that was joined the Suspendible Thread
2321 // Set. If there's ever a cheap way to check this, we should add an
2322 // assert here.
2323
2324 // Given that this method is called at the end of a Full GC or of a
2325 // concurrent cycle, and those can be nested (i.e., a Full GC can
2326 // interrupt a concurrent cycle), the number of full collections
2327 // completed should be either one (in the case where there was no
2328 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2329 // behind the number of full collections started.
2330
2331 // This is the case for the inner caller, i.e. a Full GC.
2332 assert(concurrent ||
2333 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2334 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2335 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2336 "is inconsistent with _old_marking_cycles_completed = %u",
2337 _old_marking_cycles_started, _old_marking_cycles_completed);
2338
2339 // This is the case for the outer caller, i.e. the concurrent cycle.
2340 assert(!concurrent ||
2341 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2342 "for outer caller (concurrent cycle): "
2343 "_old_marking_cycles_started = %u "
2344 "is inconsistent with _old_marking_cycles_completed = %u",
2345 _old_marking_cycles_started, _old_marking_cycles_completed);
2346
2347 _old_marking_cycles_completed += 1;
2348
2349 // We need to clear the "in_progress" flag in the CM thread before
2350 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2351 // is set) so that if a waiter requests another System.gc() it doesn't
2352 // incorrectly see that a marking cycle is still in progress.
2353 if (concurrent) {
2354 _cmThread->set_idle();
2355 }
2356
2357 // This notify_all() will ensure that a thread that called
2358 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2359 // and it's waiting for a full GC to finish will be woken up. It is
2360 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2361 FullGCCount_lock->notify_all();
2362 }
2363
2364 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2365 GCIdMarkAndRestore conc_gc_id_mark;
2366 collector_state()->set_concurrent_cycle_started(true);
2367 _gc_timer_cm->register_gc_start(start_time);
2368
2369 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2370 trace_heap_before_gc(_gc_tracer_cm);
2371 _cmThread->set_gc_id(GCId::current());
2372 }
2373
2374 void G1CollectedHeap::register_concurrent_cycle_end() {
2375 if (collector_state()->concurrent_cycle_started()) {
2376 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2377 if (_cm->has_aborted()) {
2378 _gc_tracer_cm->report_concurrent_mode_failure();
2379 }
2380
2381 _gc_timer_cm->register_gc_end();
2382 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2383
2384 // Clear state variables to prepare for the next concurrent cycle.
2385 collector_state()->set_concurrent_cycle_started(false);
2386 _heap_summary_sent = false;
2387 }
2388 }
2389
2390 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2391 if (collector_state()->concurrent_cycle_started()) {
2392 // This function can be called when:
2393 // the cleanup pause is run
2394 // the concurrent cycle is aborted before the cleanup pause.
2395 // the concurrent cycle is aborted after the cleanup pause,
2396 // but before the concurrent cycle end has been registered.
2397 // Make sure that we only send the heap information once.
2398 if (!_heap_summary_sent) {
2399 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2400 trace_heap_after_gc(_gc_tracer_cm);
2401 _heap_summary_sent = true;
2402 }
2403 }
2404 }
2405
2406 void G1CollectedHeap::collect(GCCause::Cause cause) {
2407 assert_heap_not_locked();
2408
2409 uint gc_count_before;
2410 uint old_marking_count_before;
2411 uint full_gc_count_before;
2412 bool retry_gc;
2413
2414 do {
2415 retry_gc = false;
2416
2417 {
2418 MutexLocker ml(Heap_lock);
2419
2420 // Read the GC count while holding the Heap_lock
2421 gc_count_before = total_collections();
2422 full_gc_count_before = total_full_collections();
2423 old_marking_count_before = _old_marking_cycles_started;
2424 }
2425
2426 if (should_do_concurrent_full_gc(cause)) {
2427 // Schedule an initial-mark evacuation pause that will start a
2428 // concurrent cycle. We're setting word_size to 0 which means that
2429 // we are not requesting a post-GC allocation.
2430 VM_G1IncCollectionPause op(gc_count_before,
2431 0, /* word_size */
2432 true, /* should_initiate_conc_mark */
2433 g1_policy()->max_pause_time_ms(),
2434 cause);
2435 op.set_allocation_context(AllocationContext::current());
2436
2437 VMThread::execute(&op);
2438 if (!op.pause_succeeded()) {
2439 if (old_marking_count_before == _old_marking_cycles_started) {
2440 retry_gc = op.should_retry_gc();
2441 } else {
2442 // A Full GC happened while we were trying to schedule the
2443 // initial-mark GC. No point in starting a new cycle given
2444 // that the whole heap was collected anyway.
2445 }
2446
2447 if (retry_gc) {
2448 if (GC_locker::is_active_and_needs_gc()) {
2449 GC_locker::stall_until_clear();
2450 }
2451 }
2452 }
2453 } else {
2454 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2455 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2456
2457 // Schedule a standard evacuation pause. We're setting word_size
2458 // to 0 which means that we are not requesting a post-GC allocation.
2459 VM_G1IncCollectionPause op(gc_count_before,
2460 0, /* word_size */
2461 false, /* should_initiate_conc_mark */
2462 g1_policy()->max_pause_time_ms(),
2463 cause);
2464 VMThread::execute(&op);
2465 } else {
2466 // Schedule a Full GC.
2467 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2468 VMThread::execute(&op);
2469 }
2470 }
2471 } while (retry_gc);
2472 }
2473
2474 bool G1CollectedHeap::is_in(const void* p) const {
2475 if (_hrm.reserved().contains(p)) {
2476 // Given that we know that p is in the reserved space,
2477 // heap_region_containing() should successfully
2478 // return the containing region.
2479 HeapRegion* hr = heap_region_containing(p);
2480 return hr->is_in(p);
2481 } else {
2482 return false;
2483 }
2484 }
2485
2486 #ifdef ASSERT
2487 bool G1CollectedHeap::is_in_exact(const void* p) const {
2488 bool contains = reserved_region().contains(p);
2489 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2490 if (contains && available) {
2491 return true;
2492 } else {
2493 return false;
2494 }
2495 }
2496 #endif
2497
2498 bool G1CollectedHeap::obj_in_cs(oop obj) {
2499 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2500 return r != NULL && r->in_collection_set();
2501 }
2502
2503 // Iteration functions.
2504
2505 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2506
2507 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2508 ExtendedOopClosure* _cl;
2509 public:
2510 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2511 bool doHeapRegion(HeapRegion* r) {
2512 if (!r->is_continues_humongous()) {
2513 r->oop_iterate(_cl);
2514 }
2515 return false;
2516 }
2517 };
2518
2519 // Iterates an ObjectClosure over all objects within a HeapRegion.
2520
2521 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2522 ObjectClosure* _cl;
2523 public:
2524 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2525 bool doHeapRegion(HeapRegion* r) {
2526 if (!r->is_continues_humongous()) {
2527 r->object_iterate(_cl);
2528 }
2529 return false;
2530 }
2531 };
2532
2533 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2534 IterateObjectClosureRegionClosure blk(cl);
2535 heap_region_iterate(&blk);
2536 }
2537
2538 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2539 _hrm.iterate(cl);
2540 }
2541
2542 void
2543 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2544 uint worker_id,
2545 HeapRegionClaimer *hrclaimer,
2546 bool concurrent) const {
2547 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2548 }
2549
2550 // Clear the cached CSet starting regions and (more importantly)
2551 // the time stamps. Called when we reset the GC time stamp.
2552 void G1CollectedHeap::clear_cset_start_regions() {
2553 assert(_worker_cset_start_region != NULL, "sanity");
2554 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2555
2556 for (uint i = 0; i < ParallelGCThreads; i++) {
2557 _worker_cset_start_region[i] = NULL;
2558 _worker_cset_start_region_time_stamp[i] = 0;
2559 }
2560 }
2561
2562 // Given the id of a worker, obtain or calculate a suitable
2563 // starting region for iterating over the current collection set.
2564 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2565 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2566
2567 HeapRegion* result = NULL;
2568 unsigned gc_time_stamp = get_gc_time_stamp();
2569
2570 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2571 // Cached starting region for current worker was set
2572 // during the current pause - so it's valid.
2573 // Note: the cached starting heap region may be NULL
2574 // (when the collection set is empty).
2575 result = _worker_cset_start_region[worker_i];
2576 assert(result == NULL || result->in_collection_set(), "sanity");
2577 return result;
2578 }
2579
2580 // The cached entry was not valid so let's calculate
2581 // a suitable starting heap region for this worker.
2582
2583 // We want the parallel threads to start their collection
2584 // set iteration at different collection set regions to
2585 // avoid contention.
2586 // If we have:
2587 // n collection set regions
2588 // p threads
2589 // Then thread t will start at region floor ((t * n) / p)
2590
2591 result = g1_policy()->collection_set();
2592 uint cs_size = g1_policy()->cset_region_length();
2593 uint active_workers = workers()->active_workers();
2594
2595 uint end_ind = (cs_size * worker_i) / active_workers;
2596 uint start_ind = 0;
2597
2598 if (worker_i > 0 &&
2599 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2600 // Previous workers starting region is valid
2601 // so let's iterate from there
2602 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2603 result = _worker_cset_start_region[worker_i - 1];
2604 }
2605
2606 for (uint i = start_ind; i < end_ind; i++) {
2607 result = result->next_in_collection_set();
2608 }
2609
2610 // Note: the calculated starting heap region may be NULL
2611 // (when the collection set is empty).
2612 assert(result == NULL || result->in_collection_set(), "sanity");
2613 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2614 "should be updated only once per pause");
2615 _worker_cset_start_region[worker_i] = result;
2616 OrderAccess::storestore();
2617 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2618 return result;
2619 }
2620
2621 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2622 HeapRegion* r = g1_policy()->collection_set();
2623 while (r != NULL) {
2624 HeapRegion* next = r->next_in_collection_set();
2625 if (cl->doHeapRegion(r)) {
2626 cl->incomplete();
2627 return;
2628 }
2629 r = next;
2630 }
2631 }
2632
2633 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2634 HeapRegionClosure *cl) {
2635 if (r == NULL) {
2636 // The CSet is empty so there's nothing to do.
2637 return;
2638 }
2639
2640 assert(r->in_collection_set(),
2641 "Start region must be a member of the collection set.");
2642 HeapRegion* cur = r;
2643 while (cur != NULL) {
2644 HeapRegion* next = cur->next_in_collection_set();
2645 if (cl->doHeapRegion(cur) && false) {
2646 cl->incomplete();
2647 return;
2648 }
2649 cur = next;
2650 }
2651 cur = g1_policy()->collection_set();
2652 while (cur != r) {
2653 HeapRegion* next = cur->next_in_collection_set();
2654 if (cl->doHeapRegion(cur) && false) {
2655 cl->incomplete();
2656 return;
2657 }
2658 cur = next;
2659 }
2660 }
2661
2662 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2663 HeapRegion* result = _hrm.next_region_in_heap(from);
2664 while (result != NULL && result->is_pinned()) {
2665 result = _hrm.next_region_in_heap(result);
2666 }
2667 return result;
2668 }
2669
2670 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2671 HeapRegion* hr = heap_region_containing(addr);
2672 return hr->block_start(addr);
2673 }
2674
2675 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2676 HeapRegion* hr = heap_region_containing(addr);
2677 return hr->block_size(addr);
2678 }
2679
2680 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2681 HeapRegion* hr = heap_region_containing(addr);
2682 return hr->block_is_obj(addr);
2683 }
2684
2685 bool G1CollectedHeap::supports_tlab_allocation() const {
2686 return true;
2687 }
2688
2689 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2690 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2691 }
2692
2693 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2694 return young_list()->eden_used_bytes();
2695 }
2696
2697 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2698 // must be equal to the humongous object limit.
2699 size_t G1CollectedHeap::max_tlab_size() const {
2700 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2701 }
2702
2703 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2704 AllocationContext_t context = AllocationContext::current();
2705 return _allocator->unsafe_max_tlab_alloc(context);
2706 }
2707
2708 size_t G1CollectedHeap::max_capacity() const {
2709 return _hrm.reserved().byte_size();
2710 }
2711
2712 jlong G1CollectedHeap::millis_since_last_gc() {
2713 // assert(false, "NYI");
2714 return 0;
2715 }
2716
2717 void G1CollectedHeap::prepare_for_verify() {
2718 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2719 ensure_parsability(false);
2720 }
2721 g1_rem_set()->prepare_for_verify();
2722 }
2723
2724 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2725 VerifyOption vo) {
2726 switch (vo) {
2727 case VerifyOption_G1UsePrevMarking:
2728 return hr->obj_allocated_since_prev_marking(obj);
2729 case VerifyOption_G1UseNextMarking:
2730 return hr->obj_allocated_since_next_marking(obj);
2731 case VerifyOption_G1UseMarkWord:
2732 return false;
2733 default:
2734 ShouldNotReachHere();
2735 }
2736 return false; // keep some compilers happy
2737 }
2738
2739 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2740 switch (vo) {
2741 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2742 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2743 case VerifyOption_G1UseMarkWord: return NULL;
2744 default: ShouldNotReachHere();
2745 }
2746 return NULL; // keep some compilers happy
2747 }
2748
2749 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2750 switch (vo) {
2751 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2752 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2753 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2754 default: ShouldNotReachHere();
2755 }
2756 return false; // keep some compilers happy
2757 }
2758
2759 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2760 switch (vo) {
2761 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2762 case VerifyOption_G1UseNextMarking: return "NTAMS";
2763 case VerifyOption_G1UseMarkWord: return "NONE";
2764 default: ShouldNotReachHere();
2765 }
2766 return NULL; // keep some compilers happy
2767 }
2768
2769 class VerifyRootsClosure: public OopClosure {
2770 private:
2771 G1CollectedHeap* _g1h;
2772 VerifyOption _vo;
2773 bool _failures;
2774 public:
2775 // _vo == UsePrevMarking -> use "prev" marking information,
2776 // _vo == UseNextMarking -> use "next" marking information,
2777 // _vo == UseMarkWord -> use mark word from object header.
2778 VerifyRootsClosure(VerifyOption vo) :
2779 _g1h(G1CollectedHeap::heap()),
2780 _vo(vo),
2781 _failures(false) { }
2782
2783 bool failures() { return _failures; }
2784
2785 template <class T> void do_oop_nv(T* p) {
2786 T heap_oop = oopDesc::load_heap_oop(p);
2787 if (!oopDesc::is_null(heap_oop)) {
2788 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2789 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2790 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2791 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2792 if (_vo == VerifyOption_G1UseMarkWord) {
2793 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2794 }
2795 obj->print_on(gclog_or_tty);
2796 _failures = true;
2797 }
2798 }
2799 }
2800
2801 void do_oop(oop* p) { do_oop_nv(p); }
2802 void do_oop(narrowOop* p) { do_oop_nv(p); }
2803 };
2804
2805 class G1VerifyCodeRootOopClosure: public OopClosure {
2806 G1CollectedHeap* _g1h;
2807 OopClosure* _root_cl;
2808 nmethod* _nm;
2809 VerifyOption _vo;
2810 bool _failures;
2811
2812 template <class T> void do_oop_work(T* p) {
2813 // First verify that this root is live
2814 _root_cl->do_oop(p);
2815
2816 if (!G1VerifyHeapRegionCodeRoots) {
2817 // We're not verifying the code roots attached to heap region.
2818 return;
2819 }
2820
2821 // Don't check the code roots during marking verification in a full GC
2822 if (_vo == VerifyOption_G1UseMarkWord) {
2823 return;
2824 }
2825
2826 // Now verify that the current nmethod (which contains p) is
2827 // in the code root list of the heap region containing the
2828 // object referenced by p.
2829
2830 T heap_oop = oopDesc::load_heap_oop(p);
2831 if (!oopDesc::is_null(heap_oop)) {
2832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2833
2834 // Now fetch the region containing the object
2835 HeapRegion* hr = _g1h->heap_region_containing(obj);
2836 HeapRegionRemSet* hrrs = hr->rem_set();
2837 // Verify that the strong code root list for this region
2838 // contains the nmethod
2839 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2840 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2841 "from nmethod " PTR_FORMAT " not in strong "
2842 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2843 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2844 _failures = true;
2845 }
2846 }
2847 }
2848
2849 public:
2850 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2851 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2852
2853 void do_oop(oop* p) { do_oop_work(p); }
2854 void do_oop(narrowOop* p) { do_oop_work(p); }
2855
2856 void set_nmethod(nmethod* nm) { _nm = nm; }
2857 bool failures() { return _failures; }
2858 };
2859
2860 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2861 G1VerifyCodeRootOopClosure* _oop_cl;
2862
2863 public:
2864 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2865 _oop_cl(oop_cl) {}
2866
2867 void do_code_blob(CodeBlob* cb) {
2868 nmethod* nm = cb->as_nmethod_or_null();
2869 if (nm != NULL) {
2870 _oop_cl->set_nmethod(nm);
2871 nm->oops_do(_oop_cl);
2872 }
2873 }
2874 };
2875
2876 class YoungRefCounterClosure : public OopClosure {
2877 G1CollectedHeap* _g1h;
2878 int _count;
2879 public:
2880 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2881 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2882 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2883
2884 int count() { return _count; }
2885 void reset_count() { _count = 0; };
2886 };
2887
2888 class VerifyKlassClosure: public KlassClosure {
2889 YoungRefCounterClosure _young_ref_counter_closure;
2890 OopClosure *_oop_closure;
2891 public:
2892 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2893 void do_klass(Klass* k) {
2894 k->oops_do(_oop_closure);
2895
2896 _young_ref_counter_closure.reset_count();
2897 k->oops_do(&_young_ref_counter_closure);
2898 if (_young_ref_counter_closure.count() > 0) {
2899 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2900 }
2901 }
2902 };
2903
2904 class VerifyLivenessOopClosure: public OopClosure {
2905 G1CollectedHeap* _g1h;
2906 VerifyOption _vo;
2907 public:
2908 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2909 _g1h(g1h), _vo(vo)
2910 { }
2911 void do_oop(narrowOop *p) { do_oop_work(p); }
2912 void do_oop( oop *p) { do_oop_work(p); }
2913
2914 template <class T> void do_oop_work(T *p) {
2915 oop obj = oopDesc::load_decode_heap_oop(p);
2916 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2917 "Dead object referenced by a not dead object");
2918 }
2919 };
2920
2921 class VerifyObjsInRegionClosure: public ObjectClosure {
2922 private:
2923 G1CollectedHeap* _g1h;
2924 size_t _live_bytes;
2925 HeapRegion *_hr;
2926 VerifyOption _vo;
2927 public:
2928 // _vo == UsePrevMarking -> use "prev" marking information,
2929 // _vo == UseNextMarking -> use "next" marking information,
2930 // _vo == UseMarkWord -> use mark word from object header.
2931 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2932 : _live_bytes(0), _hr(hr), _vo(vo) {
2933 _g1h = G1CollectedHeap::heap();
2934 }
2935 void do_object(oop o) {
2936 VerifyLivenessOopClosure isLive(_g1h, _vo);
2937 assert(o != NULL, "Huh?");
2938 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2939 // If the object is alive according to the mark word,
2940 // then verify that the marking information agrees.
2941 // Note we can't verify the contra-positive of the
2942 // above: if the object is dead (according to the mark
2943 // word), it may not be marked, or may have been marked
2944 // but has since became dead, or may have been allocated
2945 // since the last marking.
2946 if (_vo == VerifyOption_G1UseMarkWord) {
2947 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2948 }
2949
2950 o->oop_iterate_no_header(&isLive);
2951 if (!_hr->obj_allocated_since_prev_marking(o)) {
2952 size_t obj_size = o->size(); // Make sure we don't overflow
2953 _live_bytes += (obj_size * HeapWordSize);
2954 }
2955 }
2956 }
2957 size_t live_bytes() { return _live_bytes; }
2958 };
2959
2960 class VerifyArchiveOopClosure: public OopClosure {
2961 public:
2962 VerifyArchiveOopClosure(HeapRegion *hr) { }
2963 void do_oop(narrowOop *p) { do_oop_work(p); }
2964 void do_oop( oop *p) { do_oop_work(p); }
2965
2966 template <class T> void do_oop_work(T *p) {
2967 oop obj = oopDesc::load_decode_heap_oop(p);
2968 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2969 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2970 p2i(p), p2i(obj));
2971 }
2972 };
2973
2974 class VerifyArchiveRegionClosure: public ObjectClosure {
2975 public:
2976 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2977 // Verify that all object pointers are to archive regions.
2978 void do_object(oop o) {
2979 VerifyArchiveOopClosure checkOop(NULL);
2980 assert(o != NULL, "Should not be here for NULL oops");
2981 o->oop_iterate_no_header(&checkOop);
2982 }
2983 };
2984
2985 class VerifyRegionClosure: public HeapRegionClosure {
2986 private:
2987 bool _par;
2988 VerifyOption _vo;
2989 bool _failures;
2990 public:
2991 // _vo == UsePrevMarking -> use "prev" marking information,
2992 // _vo == UseNextMarking -> use "next" marking information,
2993 // _vo == UseMarkWord -> use mark word from object header.
2994 VerifyRegionClosure(bool par, VerifyOption vo)
2995 : _par(par),
2996 _vo(vo),
2997 _failures(false) {}
2998
2999 bool failures() {
3000 return _failures;
3001 }
3002
3003 bool doHeapRegion(HeapRegion* r) {
3004 // For archive regions, verify there are no heap pointers to
3005 // non-pinned regions. For all others, verify liveness info.
3006 if (r->is_archive()) {
3007 VerifyArchiveRegionClosure verify_oop_pointers(r);
3008 r->object_iterate(&verify_oop_pointers);
3009 return true;
3010 }
3011 if (!r->is_continues_humongous()) {
3012 bool failures = false;
3013 r->verify(_vo, &failures);
3014 if (failures) {
3015 _failures = true;
3016 } else if (!r->is_starts_humongous()) {
3017 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3018 r->object_iterate(¬_dead_yet_cl);
3019 if (_vo != VerifyOption_G1UseNextMarking) {
3020 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3021 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3022 "max_live_bytes " SIZE_FORMAT " "
3023 "< calculated " SIZE_FORMAT,
3024 p2i(r->bottom()), p2i(r->end()),
3025 r->max_live_bytes(),
3026 not_dead_yet_cl.live_bytes());
3027 _failures = true;
3028 }
3029 } else {
3030 // When vo == UseNextMarking we cannot currently do a sanity
3031 // check on the live bytes as the calculation has not been
3032 // finalized yet.
3033 }
3034 }
3035 }
3036 return false; // stop the region iteration if we hit a failure
3037 }
3038 };
3039
3040 // This is the task used for parallel verification of the heap regions
3041
3042 class G1ParVerifyTask: public AbstractGangTask {
3043 private:
3044 G1CollectedHeap* _g1h;
3045 VerifyOption _vo;
3046 bool _failures;
3047 HeapRegionClaimer _hrclaimer;
3048
3049 public:
3050 // _vo == UsePrevMarking -> use "prev" marking information,
3051 // _vo == UseNextMarking -> use "next" marking information,
3052 // _vo == UseMarkWord -> use mark word from object header.
3053 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3054 AbstractGangTask("Parallel verify task"),
3055 _g1h(g1h),
3056 _vo(vo),
3057 _failures(false),
3058 _hrclaimer(g1h->workers()->active_workers()) {}
3059
3060 bool failures() {
3061 return _failures;
3062 }
3063
3064 void work(uint worker_id) {
3065 HandleMark hm;
3066 VerifyRegionClosure blk(true, _vo);
3067 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3068 if (blk.failures()) {
3069 _failures = true;
3070 }
3071 }
3072 };
3073
3074 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3075 if (SafepointSynchronize::is_at_safepoint()) {
3076 assert(Thread::current()->is_VM_thread(),
3077 "Expected to be executed serially by the VM thread at this point");
3078
3079 if (!silent) { gclog_or_tty->print("Roots "); }
3080 VerifyRootsClosure rootsCl(vo);
3081 VerifyKlassClosure klassCl(this, &rootsCl);
3082 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3083
3084 // We apply the relevant closures to all the oops in the
3085 // system dictionary, class loader data graph, the string table
3086 // and the nmethods in the code cache.
3087 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3088 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3089
3090 {
3091 G1RootProcessor root_processor(this, 1);
3092 root_processor.process_all_roots(&rootsCl,
3093 &cldCl,
3094 &blobsCl);
3095 }
3096
3097 bool failures = rootsCl.failures() || codeRootsCl.failures();
3098
3099 if (vo != VerifyOption_G1UseMarkWord) {
3100 // If we're verifying during a full GC then the region sets
3101 // will have been torn down at the start of the GC. Therefore
3102 // verifying the region sets will fail. So we only verify
3103 // the region sets when not in a full GC.
3104 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3105 verify_region_sets();
3106 }
3107
3108 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3109 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3110
3111 G1ParVerifyTask task(this, vo);
3112 workers()->run_task(&task);
3113 if (task.failures()) {
3114 failures = true;
3115 }
3116
3117 } else {
3118 VerifyRegionClosure blk(false, vo);
3119 heap_region_iterate(&blk);
3120 if (blk.failures()) {
3121 failures = true;
3122 }
3123 }
3124
3125 if (G1StringDedup::is_enabled()) {
3126 if (!silent) gclog_or_tty->print("StrDedup ");
3127 G1StringDedup::verify();
3128 }
3129
3130 if (failures) {
3131 gclog_or_tty->print_cr("Heap:");
3132 // It helps to have the per-region information in the output to
3133 // help us track down what went wrong. This is why we call
3134 // print_extended_on() instead of print_on().
3135 print_extended_on(gclog_or_tty);
3136 gclog_or_tty->cr();
3137 gclog_or_tty->flush();
3138 }
3139 guarantee(!failures, "there should not have been any failures");
3140 } else {
3141 if (!silent) {
3142 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3143 if (G1StringDedup::is_enabled()) {
3144 gclog_or_tty->print(", StrDedup");
3145 }
3146 gclog_or_tty->print(") ");
3147 }
3148 }
3149 }
3150
3151 void G1CollectedHeap::verify(bool silent) {
3152 verify(silent, VerifyOption_G1UsePrevMarking);
3153 }
3154
3155 double G1CollectedHeap::verify(bool guard, const char* msg) {
3156 double verify_time_ms = 0.0;
3157
3158 if (guard && total_collections() >= VerifyGCStartAt) {
3159 double verify_start = os::elapsedTime();
3160 HandleMark hm; // Discard invalid handles created during verification
3161 prepare_for_verify();
3162 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3163 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3164 }
3165
3166 return verify_time_ms;
3167 }
3168
3169 void G1CollectedHeap::verify_before_gc() {
3170 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3171 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3172 }
3173
3174 void G1CollectedHeap::verify_after_gc() {
3175 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3176 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3177 }
3178
3179 class PrintRegionClosure: public HeapRegionClosure {
3180 outputStream* _st;
3181 public:
3182 PrintRegionClosure(outputStream* st) : _st(st) {}
3183 bool doHeapRegion(HeapRegion* r) {
3184 r->print_on(_st);
3185 return false;
3186 }
3187 };
3188
3189 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3190 const HeapRegion* hr,
3191 const VerifyOption vo) const {
3192 switch (vo) {
3193 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3194 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3195 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3196 default: ShouldNotReachHere();
3197 }
3198 return false; // keep some compilers happy
3199 }
3200
3201 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3202 const VerifyOption vo) const {
3203 switch (vo) {
3204 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3205 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3206 case VerifyOption_G1UseMarkWord: {
3207 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3208 return !obj->is_gc_marked() && !hr->is_archive();
3209 }
3210 default: ShouldNotReachHere();
3211 }
3212 return false; // keep some compilers happy
3213 }
3214
3215 void G1CollectedHeap::print_on(outputStream* st) const {
3216 st->print(" %-20s", "garbage-first heap");
3217 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3218 capacity()/K, used_unlocked()/K);
3219 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3220 p2i(_hrm.reserved().start()),
3221 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3222 p2i(_hrm.reserved().end()));
3223 st->cr();
3224 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3225 uint young_regions = _young_list->length();
3226 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3227 (size_t) young_regions * HeapRegion::GrainBytes / K);
3228 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3229 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3230 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3231 st->cr();
3232 MetaspaceAux::print_on(st);
3233 }
3234
3235 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3236 print_on(st);
3237
3238 // Print the per-region information.
3239 st->cr();
3240 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3241 "HS=humongous(starts), HC=humongous(continues), "
3242 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3243 "PTAMS=previous top-at-mark-start, "
3244 "NTAMS=next top-at-mark-start)");
3245 PrintRegionClosure blk(st);
3246 heap_region_iterate(&blk);
3247 }
3248
3249 void G1CollectedHeap::print_on_error(outputStream* st) const {
3250 this->CollectedHeap::print_on_error(st);
3251
3252 if (_cm != NULL) {
3253 st->cr();
3254 _cm->print_on_error(st);
3255 }
3256 }
3257
3258 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3259 workers()->print_worker_threads_on(st);
3260 _cmThread->print_on(st);
3261 st->cr();
3262 _cm->print_worker_threads_on(st);
3263 _cg1r->print_worker_threads_on(st);
3264 if (G1StringDedup::is_enabled()) {
3265 G1StringDedup::print_worker_threads_on(st);
3266 }
3267 }
3268
3269 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3270 workers()->threads_do(tc);
3271 tc->do_thread(_cmThread);
3272 _cg1r->threads_do(tc);
3273 if (G1StringDedup::is_enabled()) {
3274 G1StringDedup::threads_do(tc);
3275 }
3276 }
3277
3278 void G1CollectedHeap::print_tracing_info() const {
3279 // We'll overload this to mean "trace GC pause statistics."
3280 if (TraceYoungGenTime || TraceOldGenTime) {
3281 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3282 // to that.
3283 g1_policy()->print_tracing_info();
3284 }
3285 if (G1SummarizeRSetStats) {
3286 g1_rem_set()->print_summary_info();
3287 }
3288 if (G1SummarizeConcMark) {
3289 concurrent_mark()->print_summary_info();
3290 }
3291 g1_policy()->print_yg_surv_rate_info();
3292 }
3293
3294 #ifndef PRODUCT
3295 // Helpful for debugging RSet issues.
3296
3297 class PrintRSetsClosure : public HeapRegionClosure {
3298 private:
3299 const char* _msg;
3300 size_t _occupied_sum;
3301
3302 public:
3303 bool doHeapRegion(HeapRegion* r) {
3304 HeapRegionRemSet* hrrs = r->rem_set();
3305 size_t occupied = hrrs->occupied();
3306 _occupied_sum += occupied;
3307
3308 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3309 HR_FORMAT_PARAMS(r));
3310 if (occupied == 0) {
3311 gclog_or_tty->print_cr(" RSet is empty");
3312 } else {
3313 hrrs->print();
3314 }
3315 gclog_or_tty->print_cr("----------");
3316 return false;
3317 }
3318
3319 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3320 gclog_or_tty->cr();
3321 gclog_or_tty->print_cr("========================================");
3322 gclog_or_tty->print_cr("%s", msg);
3323 gclog_or_tty->cr();
3324 }
3325
3326 ~PrintRSetsClosure() {
3327 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3328 gclog_or_tty->print_cr("========================================");
3329 gclog_or_tty->cr();
3330 }
3331 };
3332
3333 void G1CollectedHeap::print_cset_rsets() {
3334 PrintRSetsClosure cl("Printing CSet RSets");
3335 collection_set_iterate(&cl);
3336 }
3337
3338 void G1CollectedHeap::print_all_rsets() {
3339 PrintRSetsClosure cl("Printing All RSets");;
3340 heap_region_iterate(&cl);
3341 }
3342 #endif // PRODUCT
3343
3344 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3345 YoungList* young_list = heap()->young_list();
3346
3347 size_t eden_used_bytes = young_list->eden_used_bytes();
3348 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3349
3350 size_t eden_capacity_bytes =
3351 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3352
3353 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3354 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3355 }
3356
3357 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3358 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3359 stats->unused(), stats->used(), stats->region_end_waste(),
3360 stats->regions_filled(), stats->direct_allocated(),
3361 stats->failure_used(), stats->failure_waste());
3362 }
3363
3364 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3365 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3366 gc_tracer->report_gc_heap_summary(when, heap_summary);
3367
3368 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3369 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3370 }
3371
3372
3373 G1CollectedHeap* G1CollectedHeap::heap() {
3374 CollectedHeap* heap = Universe::heap();
3375 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3376 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3377 return (G1CollectedHeap*)heap;
3378 }
3379
3380 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3381 // always_do_update_barrier = false;
3382 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3383 // Fill TLAB's and such
3384 accumulate_statistics_all_tlabs();
3385 ensure_parsability(true);
3386
3387 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3388 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3389 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3390 }
3391 }
3392
3393 void G1CollectedHeap::gc_epilogue(bool full) {
3394
3395 if (G1SummarizeRSetStats &&
3396 (G1SummarizeRSetStatsPeriod > 0) &&
3397 // we are at the end of the GC. Total collections has already been increased.
3398 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3399 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3400 }
3401
3402 // FIXME: what is this about?
3403 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3404 // is set.
3405 #if defined(COMPILER2) || INCLUDE_JVMCI
3406 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3407 #endif
3408 // always_do_update_barrier = true;
3409
3410 resize_all_tlabs();
3411 allocation_context_stats().update(full);
3412
3413 // We have just completed a GC. Update the soft reference
3414 // policy with the new heap occupancy
3415 Universe::update_heap_info_at_gc();
3416 }
3417
3418 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3419 uint gc_count_before,
3420 bool* succeeded,
3421 GCCause::Cause gc_cause) {
3422 assert_heap_not_locked_and_not_at_safepoint();
3423 g1_policy()->record_stop_world_start();
3424 VM_G1IncCollectionPause op(gc_count_before,
3425 word_size,
3426 false, /* should_initiate_conc_mark */
3427 g1_policy()->max_pause_time_ms(),
3428 gc_cause);
3429
3430 op.set_allocation_context(AllocationContext::current());
3431 VMThread::execute(&op);
3432
3433 HeapWord* result = op.result();
3434 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3435 assert(result == NULL || ret_succeeded,
3436 "the result should be NULL if the VM did not succeed");
3437 *succeeded = ret_succeeded;
3438
3439 assert_heap_not_locked();
3440 return result;
3441 }
3442
3443 void
3444 G1CollectedHeap::doConcurrentMark() {
3445 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3446 if (!_cmThread->in_progress()) {
3447 _cmThread->set_started();
3448 CGC_lock->notify();
3449 }
3450 }
3451
3452 size_t G1CollectedHeap::pending_card_num() {
3453 size_t extra_cards = 0;
3454 JavaThread *curr = Threads::first();
3455 while (curr != NULL) {
3456 DirtyCardQueue& dcq = curr->dirty_card_queue();
3457 extra_cards += dcq.size();
3458 curr = curr->next();
3459 }
3460 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3461 size_t buffer_size = dcqs.buffer_size();
3462 size_t buffer_num = dcqs.completed_buffers_num();
3463
3464 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3465 // in bytes - not the number of 'entries'. We need to convert
3466 // into a number of cards.
3467 return (buffer_size * buffer_num + extra_cards) / oopSize;
3468 }
3469
3470 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3471 private:
3472 size_t _total_humongous;
3473 size_t _candidate_humongous;
3474
3475 DirtyCardQueue _dcq;
3476
3477 // We don't nominate objects with many remembered set entries, on
3478 // the assumption that such objects are likely still live.
3479 bool is_remset_small(HeapRegion* region) const {
3480 HeapRegionRemSet* const rset = region->rem_set();
3481 return G1EagerReclaimHumongousObjectsWithStaleRefs
3482 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3483 : rset->is_empty();
3484 }
3485
3486 bool is_typeArray_region(HeapRegion* region) const {
3487 return oop(region->bottom())->is_typeArray();
3488 }
3489
3490 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3491 assert(region->is_starts_humongous(), "Must start a humongous object");
3492
3493 // Candidate selection must satisfy the following constraints
3494 // while concurrent marking is in progress:
3495 //
3496 // * In order to maintain SATB invariants, an object must not be
3497 // reclaimed if it was allocated before the start of marking and
3498 // has not had its references scanned. Such an object must have
3499 // its references (including type metadata) scanned to ensure no
3500 // live objects are missed by the marking process. Objects
3501 // allocated after the start of concurrent marking don't need to
3502 // be scanned.
3503 //
3504 // * An object must not be reclaimed if it is on the concurrent
3505 // mark stack. Objects allocated after the start of concurrent
3506 // marking are never pushed on the mark stack.
3507 //
3508 // Nominating only objects allocated after the start of concurrent
3509 // marking is sufficient to meet both constraints. This may miss
3510 // some objects that satisfy the constraints, but the marking data
3511 // structures don't support efficiently performing the needed
3512 // additional tests or scrubbing of the mark stack.
3513 //
3514 // However, we presently only nominate is_typeArray() objects.
3515 // A humongous object containing references induces remembered
3516 // set entries on other regions. In order to reclaim such an
3517 // object, those remembered sets would need to be cleaned up.
3518 //
3519 // We also treat is_typeArray() objects specially, allowing them
3520 // to be reclaimed even if allocated before the start of
3521 // concurrent mark. For this we rely on mark stack insertion to
3522 // exclude is_typeArray() objects, preventing reclaiming an object
3523 // that is in the mark stack. We also rely on the metadata for
3524 // such objects to be built-in and so ensured to be kept live.
3525 // Frequent allocation and drop of large binary blobs is an
3526 // important use case for eager reclaim, and this special handling
3527 // may reduce needed headroom.
3528
3529 return is_typeArray_region(region) && is_remset_small(region);
3530 }
3531
3532 public:
3533 RegisterHumongousWithInCSetFastTestClosure()
3534 : _total_humongous(0),
3535 _candidate_humongous(0),
3536 _dcq(&JavaThread::dirty_card_queue_set()) {
3537 }
3538
3539 virtual bool doHeapRegion(HeapRegion* r) {
3540 if (!r->is_starts_humongous()) {
3541 return false;
3542 }
3543 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3544
3545 bool is_candidate = humongous_region_is_candidate(g1h, r);
3546 uint rindex = r->hrm_index();
3547 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3548 if (is_candidate) {
3549 _candidate_humongous++;
3550 g1h->register_humongous_region_with_cset(rindex);
3551 // Is_candidate already filters out humongous object with large remembered sets.
3552 // If we have a humongous object with a few remembered sets, we simply flush these
3553 // remembered set entries into the DCQS. That will result in automatic
3554 // re-evaluation of their remembered set entries during the following evacuation
3555 // phase.
3556 if (!r->rem_set()->is_empty()) {
3557 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3558 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3559 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3560 HeapRegionRemSetIterator hrrs(r->rem_set());
3561 size_t card_index;
3562 while (hrrs.has_next(card_index)) {
3563 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3564 // The remembered set might contain references to already freed
3565 // regions. Filter out such entries to avoid failing card table
3566 // verification.
3567 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3568 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3569 *card_ptr = CardTableModRefBS::dirty_card_val();
3570 _dcq.enqueue(card_ptr);
3571 }
3572 }
3573 }
3574 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3575 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3576 hrrs.n_yielded(), r->rem_set()->occupied());
3577 r->rem_set()->clear_locked();
3578 }
3579 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3580 }
3581 _total_humongous++;
3582
3583 return false;
3584 }
3585
3586 size_t total_humongous() const { return _total_humongous; }
3587 size_t candidate_humongous() const { return _candidate_humongous; }
3588
3589 void flush_rem_set_entries() { _dcq.flush(); }
3590 };
3591
3592 void G1CollectedHeap::register_humongous_regions_with_cset() {
3593 if (!G1EagerReclaimHumongousObjects) {
3594 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3595 return;
3596 }
3597 double time = os::elapsed_counter();
3598
3599 // Collect reclaim candidate information and register candidates with cset.
3600 RegisterHumongousWithInCSetFastTestClosure cl;
3601 heap_region_iterate(&cl);
3602
3603 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3604 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3605 cl.total_humongous(),
3606 cl.candidate_humongous());
3607 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3608
3609 // Finally flush all remembered set entries to re-check into the global DCQS.
3610 cl.flush_rem_set_entries();
3611 }
3612
3613 #ifdef ASSERT
3614 class VerifyCSetClosure: public HeapRegionClosure {
3615 public:
3616 bool doHeapRegion(HeapRegion* hr) {
3617 // Here we check that the CSet region's RSet is ready for parallel
3618 // iteration. The fields that we'll verify are only manipulated
3619 // when the region is part of a CSet and is collected. Afterwards,
3620 // we reset these fields when we clear the region's RSet (when the
3621 // region is freed) so they are ready when the region is
3622 // re-allocated. The only exception to this is if there's an
3623 // evacuation failure and instead of freeing the region we leave
3624 // it in the heap. In that case, we reset these fields during
3625 // evacuation failure handling.
3626 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3627
3628 // Here's a good place to add any other checks we'd like to
3629 // perform on CSet regions.
3630 return false;
3631 }
3632 };
3633 #endif // ASSERT
3634
3635 uint G1CollectedHeap::num_task_queues() const {
3636 return _task_queues->size();
3637 }
3638
3639 #if TASKQUEUE_STATS
3640 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3641 st->print_raw_cr("GC Task Stats");
3642 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3643 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3644 }
3645
3646 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3647 print_taskqueue_stats_hdr(st);
3648
3649 TaskQueueStats totals;
3650 const uint n = num_task_queues();
3651 for (uint i = 0; i < n; ++i) {
3652 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3653 totals += task_queue(i)->stats;
3654 }
3655 st->print_raw("tot "); totals.print(st); st->cr();
3656
3657 DEBUG_ONLY(totals.verify());
3658 }
3659
3660 void G1CollectedHeap::reset_taskqueue_stats() {
3661 const uint n = num_task_queues();
3662 for (uint i = 0; i < n; ++i) {
3663 task_queue(i)->stats.reset();
3664 }
3665 }
3666 #endif // TASKQUEUE_STATS
3667
3668 void G1CollectedHeap::log_gc_header() {
3669 if (!G1Log::fine()) {
3670 return;
3671 }
3672
3673 gclog_or_tty->gclog_stamp();
3674
3675 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3676 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3677 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3678
3679 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3680 }
3681
3682 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3683 if (!G1Log::fine()) {
3684 return;
3685 }
3686
3687 if (G1Log::finer()) {
3688 if (evacuation_failed()) {
3689 gclog_or_tty->print(" (to-space exhausted)");
3690 }
3691 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3692 g1_policy()->print_phases(pause_time_sec);
3693 g1_policy()->print_detailed_heap_transition();
3694 } else {
3695 if (evacuation_failed()) {
3696 gclog_or_tty->print("--");
3697 }
3698 g1_policy()->print_heap_transition();
3699 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3700 }
3701 gclog_or_tty->flush();
3702 }
3703
3704 void G1CollectedHeap::wait_for_root_region_scanning() {
3705 double scan_wait_start = os::elapsedTime();
3706 // We have to wait until the CM threads finish scanning the
3707 // root regions as it's the only way to ensure that all the
3708 // objects on them have been correctly scanned before we start
3709 // moving them during the GC.
3710 bool waited = _cm->root_regions()->wait_until_scan_finished();
3711 double wait_time_ms = 0.0;
3712 if (waited) {
3713 double scan_wait_end = os::elapsedTime();
3714 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3715 }
3716 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3717 }
3718
3719 bool
3720 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3721 assert_at_safepoint(true /* should_be_vm_thread */);
3722 guarantee(!is_gc_active(), "collection is not reentrant");
3723
3724 if (GC_locker::check_active_before_gc()) {
3725 return false;
3726 }
3727
3728 _gc_timer_stw->register_gc_start();
3729
3730 GCIdMark gc_id_mark;
3731 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3732
3733 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3734 ResourceMark rm;
3735
3736 wait_for_root_region_scanning();
3737
3738 G1Log::update_level();
3739 print_heap_before_gc();
3740 trace_heap_before_gc(_gc_tracer_stw);
3741
3742 verify_region_sets_optional();
3743 verify_dirty_young_regions();
3744
3745 // This call will decide whether this pause is an initial-mark
3746 // pause. If it is, during_initial_mark_pause() will return true
3747 // for the duration of this pause.
3748 g1_policy()->decide_on_conc_mark_initiation();
3749
3750 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3751 assert(!collector_state()->during_initial_mark_pause() ||
3752 collector_state()->gcs_are_young(), "sanity");
3753
3754 // We also do not allow mixed GCs during marking.
3755 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3756
3757 // Record whether this pause is an initial mark. When the current
3758 // thread has completed its logging output and it's safe to signal
3759 // the CM thread, the flag's value in the policy has been reset.
3760 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3761
3762 // Inner scope for scope based logging, timers, and stats collection
3763 {
3764 EvacuationInfo evacuation_info;
3765
3766 if (collector_state()->during_initial_mark_pause()) {
3767 // We are about to start a marking cycle, so we increment the
3768 // full collection counter.
3769 increment_old_marking_cycles_started();
3770 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3771 }
3772
3773 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3774
3775 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3776
3777 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3778 workers()->active_workers(),
3779 Threads::number_of_non_daemon_threads());
3780 workers()->set_active_workers(active_workers);
3781
3782 double pause_start_sec = os::elapsedTime();
3783 g1_policy()->note_gc_start(active_workers);
3784 log_gc_header();
3785
3786 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3787 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3788
3789 // If the secondary_free_list is not empty, append it to the
3790 // free_list. No need to wait for the cleanup operation to finish;
3791 // the region allocation code will check the secondary_free_list
3792 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3793 // set, skip this step so that the region allocation code has to
3794 // get entries from the secondary_free_list.
3795 if (!G1StressConcRegionFreeing) {
3796 append_secondary_free_list_if_not_empty_with_lock();
3797 }
3798
3799 assert(check_young_list_well_formed(), "young list should be well formed");
3800
3801 // Don't dynamically change the number of GC threads this early. A value of
3802 // 0 is used to indicate serial work. When parallel work is done,
3803 // it will be set.
3804
3805 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3806 IsGCActiveMark x;
3807
3808 gc_prologue(false);
3809 increment_total_collections(false /* full gc */);
3810 increment_gc_time_stamp();
3811
3812 verify_before_gc();
3813
3814 check_bitmaps("GC Start");
3815
3816 #if defined(COMPILER2) || INCLUDE_JVMCI
3817 DerivedPointerTable::clear();
3818 #endif
3819
3820 // Please see comment in g1CollectedHeap.hpp and
3821 // G1CollectedHeap::ref_processing_init() to see how
3822 // reference processing currently works in G1.
3823
3824 // Enable discovery in the STW reference processor
3825 ref_processor_stw()->enable_discovery();
3826
3827 {
3828 // We want to temporarily turn off discovery by the
3829 // CM ref processor, if necessary, and turn it back on
3830 // on again later if we do. Using a scoped
3831 // NoRefDiscovery object will do this.
3832 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3833
3834 // Forget the current alloc region (we might even choose it to be part
3835 // of the collection set!).
3836 _allocator->release_mutator_alloc_region();
3837
3838 // We should call this after we retire the mutator alloc
3839 // region(s) so that all the ALLOC / RETIRE events are generated
3840 // before the start GC event.
3841 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3842
3843 // This timing is only used by the ergonomics to handle our pause target.
3844 // It is unclear why this should not include the full pause. We will
3845 // investigate this in CR 7178365.
3846 //
3847 // Preserving the old comment here if that helps the investigation:
3848 //
3849 // The elapsed time induced by the start time below deliberately elides
3850 // the possible verification above.
3851 double sample_start_time_sec = os::elapsedTime();
3852
3853 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3854
3855 if (collector_state()->during_initial_mark_pause()) {
3856 concurrent_mark()->checkpointRootsInitialPre();
3857 }
3858
3859 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3860 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3861
3862 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3863
3864 // Make sure the remembered sets are up to date. This needs to be
3865 // done before register_humongous_regions_with_cset(), because the
3866 // remembered sets are used there to choose eager reclaim candidates.
3867 // If the remembered sets are not up to date we might miss some
3868 // entries that need to be handled.
3869 g1_rem_set()->cleanupHRRS();
3870
3871 register_humongous_regions_with_cset();
3872
3873 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3874
3875 _cm->note_start_of_gc();
3876 // We call this after finalize_cset() to
3877 // ensure that the CSet has been finalized.
3878 _cm->verify_no_cset_oops();
3879
3880 if (_hr_printer.is_active()) {
3881 HeapRegion* hr = g1_policy()->collection_set();
3882 while (hr != NULL) {
3883 _hr_printer.cset(hr);
3884 hr = hr->next_in_collection_set();
3885 }
3886 }
3887
3888 #ifdef ASSERT
3889 VerifyCSetClosure cl;
3890 collection_set_iterate(&cl);
3891 #endif // ASSERT
3892
3893 // Initialize the GC alloc regions.
3894 _allocator->init_gc_alloc_regions(evacuation_info);
3895
3896 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3897 pre_evacuate_collection_set();
3898
3899 // Actually do the work...
3900 evacuate_collection_set(evacuation_info, &per_thread_states);
3901
3902 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3903
3904 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3905 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3906
3907 eagerly_reclaim_humongous_regions();
3908
3909 g1_policy()->clear_collection_set();
3910
3911 // Start a new incremental collection set for the next pause.
3912 g1_policy()->start_incremental_cset_building();
3913
3914 clear_cset_fast_test();
3915
3916 _young_list->reset_sampled_info();
3917
3918 // Don't check the whole heap at this point as the
3919 // GC alloc regions from this pause have been tagged
3920 // as survivors and moved on to the survivor list.
3921 // Survivor regions will fail the !is_young() check.
3922 assert(check_young_list_empty(false /* check_heap */),
3923 "young list should be empty");
3924
3925 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3926 _young_list->first_survivor_region(),
3927 _young_list->last_survivor_region());
3928
3929 _young_list->reset_auxilary_lists();
3930
3931 if (evacuation_failed()) {
3932 set_used(recalculate_used());
3933 if (_archive_allocator != NULL) {
3934 _archive_allocator->clear_used();
3935 }
3936 for (uint i = 0; i < ParallelGCThreads; i++) {
3937 if (_evacuation_failed_info_array[i].has_failed()) {
3938 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3939 }
3940 }
3941 } else {
3942 // The "used" of the the collection set have already been subtracted
3943 // when they were freed. Add in the bytes evacuated.
3944 increase_used(g1_policy()->bytes_copied_during_gc());
3945 }
3946
3947 if (collector_state()->during_initial_mark_pause()) {
3948 // We have to do this before we notify the CM threads that
3949 // they can start working to make sure that all the
3950 // appropriate initialization is done on the CM object.
3951 concurrent_mark()->checkpointRootsInitialPost();
3952 collector_state()->set_mark_in_progress(true);
3953 // Note that we don't actually trigger the CM thread at
3954 // this point. We do that later when we're sure that
3955 // the current thread has completed its logging output.
3956 }
3957
3958 allocate_dummy_regions();
3959
3960 _allocator->init_mutator_alloc_region();
3961
3962 {
3963 size_t expand_bytes = g1_policy()->expansion_amount();
3964 if (expand_bytes > 0) {
3965 size_t bytes_before = capacity();
3966 // No need for an ergo verbose message here,
3967 // expansion_amount() does this when it returns a value > 0.
3968 double expand_ms;
3969 if (!expand(expand_bytes, &expand_ms)) {
3970 // We failed to expand the heap. Cannot do anything about it.
3971 }
3972 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3973 }
3974 }
3975
3976 // We redo the verification but now wrt to the new CSet which
3977 // has just got initialized after the previous CSet was freed.
3978 _cm->verify_no_cset_oops();
3979 _cm->note_end_of_gc();
3980
3981 // This timing is only used by the ergonomics to handle our pause target.
3982 // It is unclear why this should not include the full pause. We will
3983 // investigate this in CR 7178365.
3984 double sample_end_time_sec = os::elapsedTime();
3985 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3986 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3987 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3988
3989 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3990 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3991
3992 MemoryService::track_memory_usage();
3993
3994 // In prepare_for_verify() below we'll need to scan the deferred
3995 // update buffers to bring the RSets up-to-date if
3996 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3997 // the update buffers we'll probably need to scan cards on the
3998 // regions we just allocated to (i.e., the GC alloc
3999 // regions). However, during the last GC we called
4000 // set_saved_mark() on all the GC alloc regions, so card
4001 // scanning might skip the [saved_mark_word()...top()] area of
4002 // those regions (i.e., the area we allocated objects into
4003 // during the last GC). But it shouldn't. Given that
4004 // saved_mark_word() is conditional on whether the GC time stamp
4005 // on the region is current or not, by incrementing the GC time
4006 // stamp here we invalidate all the GC time stamps on all the
4007 // regions and saved_mark_word() will simply return top() for
4008 // all the regions. This is a nicer way of ensuring this rather
4009 // than iterating over the regions and fixing them. In fact, the
4010 // GC time stamp increment here also ensures that
4011 // saved_mark_word() will return top() between pauses, i.e.,
4012 // during concurrent refinement. So we don't need the
4013 // is_gc_active() check to decided which top to use when
4014 // scanning cards (see CR 7039627).
4015 increment_gc_time_stamp();
4016
4017 verify_after_gc();
4018 check_bitmaps("GC End");
4019
4020 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4021 ref_processor_stw()->verify_no_references_recorded();
4022
4023 // CM reference discovery will be re-enabled if necessary.
4024 }
4025
4026 // We should do this after we potentially expand the heap so
4027 // that all the COMMIT events are generated before the end GC
4028 // event, and after we retire the GC alloc regions so that all
4029 // RETIRE events are generated before the end GC event.
4030 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4031
4032 #ifdef TRACESPINNING
4033 ParallelTaskTerminator::print_termination_counts();
4034 #endif
4035
4036 gc_epilogue(false);
4037 }
4038
4039 // Print the remainder of the GC log output.
4040 log_gc_footer(os::elapsedTime() - pause_start_sec);
4041
4042 // It is not yet to safe to tell the concurrent mark to
4043 // start as we have some optional output below. We don't want the
4044 // output from the concurrent mark thread interfering with this
4045 // logging output either.
4046
4047 _hrm.verify_optional();
4048 verify_region_sets_optional();
4049
4050 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4051 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4052
4053 print_heap_after_gc();
4054 trace_heap_after_gc(_gc_tracer_stw);
4055
4056 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4057 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4058 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4059 // before any GC notifications are raised.
4060 g1mm()->update_sizes();
4061
4062 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4063 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4064 _gc_timer_stw->register_gc_end();
4065 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4066 }
4067 // It should now be safe to tell the concurrent mark thread to start
4068 // without its logging output interfering with the logging output
4069 // that came from the pause.
4070
4071 if (should_start_conc_mark) {
4072 // CAUTION: after the doConcurrentMark() call below,
4073 // the concurrent marking thread(s) could be running
4074 // concurrently with us. Make sure that anything after
4075 // this point does not assume that we are the only GC thread
4076 // running. Note: of course, the actual marking work will
4077 // not start until the safepoint itself is released in
4078 // SuspendibleThreadSet::desynchronize().
4079 doConcurrentMark();
4080 }
4081
4082 return true;
4083 }
4084
4085 void G1CollectedHeap::remove_self_forwarding_pointers() {
4086 double remove_self_forwards_start = os::elapsedTime();
4087
4088 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4089 workers()->run_task(&rsfp_task);
4090
4091 // Now restore saved marks, if any.
4092 for (uint i = 0; i < ParallelGCThreads; i++) {
4093 OopAndMarkOopStack& cur = _preserved_objs[i];
4094 while (!cur.is_empty()) {
4095 OopAndMarkOop elem = cur.pop();
4096 elem.set_mark();
4097 }
4098 cur.clear(true);
4099 }
4100
4101 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4102 }
4103
4104 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4105 if (!_evacuation_failed) {
4106 _evacuation_failed = true;
4107 }
4108
4109 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4110
4111 // We want to call the "for_promotion_failure" version only in the
4112 // case of a promotion failure.
4113 if (m->must_be_preserved_for_promotion_failure(obj)) {
4114 OopAndMarkOop elem(obj, m);
4115 _preserved_objs[worker_id].push(elem);
4116 }
4117 }
4118
4119 class G1ParEvacuateFollowersClosure : public VoidClosure {
4120 private:
4121 double _start_term;
4122 double _term_time;
4123 size_t _term_attempts;
4124
4125 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4126 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4127 protected:
4128 G1CollectedHeap* _g1h;
4129 G1ParScanThreadState* _par_scan_state;
4130 RefToScanQueueSet* _queues;
4131 ParallelTaskTerminator* _terminator;
4132
4133 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4134 RefToScanQueueSet* queues() { return _queues; }
4135 ParallelTaskTerminator* terminator() { return _terminator; }
4136
4137 public:
4138 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4139 G1ParScanThreadState* par_scan_state,
4140 RefToScanQueueSet* queues,
4141 ParallelTaskTerminator* terminator)
4142 : _g1h(g1h), _par_scan_state(par_scan_state),
4143 _queues(queues), _terminator(terminator),
4144 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4145
4146 void do_void();
4147
4148 double term_time() const { return _term_time; }
4149 size_t term_attempts() const { return _term_attempts; }
4150
4151 private:
4152 inline bool offer_termination();
4153 };
4154
4155 bool G1ParEvacuateFollowersClosure::offer_termination() {
4156 G1ParScanThreadState* const pss = par_scan_state();
4157 start_term_time();
4158 const bool res = terminator()->offer_termination();
4159 end_term_time();
4160 return res;
4161 }
4162
4163 void G1ParEvacuateFollowersClosure::do_void() {
4164 G1ParScanThreadState* const pss = par_scan_state();
4165 pss->trim_queue();
4166 do {
4167 pss->steal_and_trim_queue(queues());
4168 } while (!offer_termination());
4169 }
4170
4171 class G1ParTask : public AbstractGangTask {
4172 protected:
4173 G1CollectedHeap* _g1h;
4174 G1ParScanThreadStateSet* _pss;
4175 RefToScanQueueSet* _queues;
4176 G1RootProcessor* _root_processor;
4177 ParallelTaskTerminator _terminator;
4178 uint _n_workers;
4179
4180 public:
4181 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4182 : AbstractGangTask("G1 collection"),
4183 _g1h(g1h),
4184 _pss(per_thread_states),
4185 _queues(task_queues),
4186 _root_processor(root_processor),
4187 _terminator(n_workers, _queues),
4188 _n_workers(n_workers)
4189 {}
4190
4191 void work(uint worker_id) {
4192 if (worker_id >= _n_workers) return; // no work needed this round
4193
4194 double start_sec = os::elapsedTime();
4195 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4196
4197 {
4198 ResourceMark rm;
4199 HandleMark hm;
4200
4201 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4202
4203 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4204 pss->set_ref_processor(rp);
4205
4206 double start_strong_roots_sec = os::elapsedTime();
4207
4208 _root_processor->evacuate_roots(pss->closures(), worker_id);
4209
4210 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4211
4212 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4213 // treating the nmethods visited to act as roots for concurrent marking.
4214 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4215 // objects copied by the current evacuation.
4216 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4217 pss->closures()->weak_codeblobs(),
4218 worker_id);
4219
4220 _pss->add_cards_scanned(worker_id, cards_scanned);
4221
4222 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4223
4224 double term_sec = 0.0;
4225 size_t evac_term_attempts = 0;
4226 {
4227 double start = os::elapsedTime();
4228 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4229 evac.do_void();
4230
4231 evac_term_attempts = evac.term_attempts();
4232 term_sec = evac.term_time();
4233 double elapsed_sec = os::elapsedTime() - start;
4234 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4235 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4236 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4237 }
4238
4239 assert(pss->queue_is_empty(), "should be empty");
4240
4241 if (PrintTerminationStats) {
4242 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4243 size_t lab_waste;
4244 size_t lab_undo_waste;
4245 pss->waste(lab_waste, lab_undo_waste);
4246 _g1h->print_termination_stats(gclog_or_tty,
4247 worker_id,
4248 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4249 strong_roots_sec * 1000.0, /* strong roots time */
4250 term_sec * 1000.0, /* evac term time */
4251 evac_term_attempts, /* evac term attempts */
4252 lab_waste, /* alloc buffer waste */
4253 lab_undo_waste /* undo waste */
4254 );
4255 }
4256
4257 // Close the inner scope so that the ResourceMark and HandleMark
4258 // destructors are executed here and are included as part of the
4259 // "GC Worker Time".
4260 }
4261 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4262 }
4263 };
4264
4265 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4266 st->print_raw_cr("GC Termination Stats");
4267 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4268 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4269 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4270 }
4271
4272 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4273 uint worker_id,
4274 double elapsed_ms,
4275 double strong_roots_ms,
4276 double term_ms,
4277 size_t term_attempts,
4278 size_t alloc_buffer_waste,
4279 size_t undo_waste) const {
4280 st->print_cr("%3d %9.2f %9.2f %6.2f "
4281 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4282 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4283 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4284 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4285 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4286 alloc_buffer_waste * HeapWordSize / K,
4287 undo_waste * HeapWordSize / K);
4288 }
4289
4290 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4291 private:
4292 BoolObjectClosure* _is_alive;
4293 int _initial_string_table_size;
4294 int _initial_symbol_table_size;
4295
4296 bool _process_strings;
4297 int _strings_processed;
4298 int _strings_removed;
4299
4300 bool _process_symbols;
4301 int _symbols_processed;
4302 int _symbols_removed;
4303
4304 public:
4305 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4306 AbstractGangTask("String/Symbol Unlinking"),
4307 _is_alive(is_alive),
4308 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4309 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4310
4311 _initial_string_table_size = StringTable::the_table()->table_size();
4312 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4313 if (process_strings) {
4314 StringTable::clear_parallel_claimed_index();
4315 }
4316 if (process_symbols) {
4317 SymbolTable::clear_parallel_claimed_index();
4318 }
4319 }
4320
4321 ~G1StringSymbolTableUnlinkTask() {
4322 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4323 "claim value %d after unlink less than initial string table size %d",
4324 StringTable::parallel_claimed_index(), _initial_string_table_size);
4325 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4326 "claim value %d after unlink less than initial symbol table size %d",
4327 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4328
4329 if (G1TraceStringSymbolTableScrubbing) {
4330 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4331 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4332 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4333 strings_processed(), strings_removed(),
4334 symbols_processed(), symbols_removed());
4335 }
4336 }
4337
4338 void work(uint worker_id) {
4339 int strings_processed = 0;
4340 int strings_removed = 0;
4341 int symbols_processed = 0;
4342 int symbols_removed = 0;
4343 if (_process_strings) {
4344 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4345 Atomic::add(strings_processed, &_strings_processed);
4346 Atomic::add(strings_removed, &_strings_removed);
4347 }
4348 if (_process_symbols) {
4349 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4350 Atomic::add(symbols_processed, &_symbols_processed);
4351 Atomic::add(symbols_removed, &_symbols_removed);
4352 }
4353 }
4354
4355 size_t strings_processed() const { return (size_t)_strings_processed; }
4356 size_t strings_removed() const { return (size_t)_strings_removed; }
4357
4358 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4359 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4360 };
4361
4362 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4363 private:
4364 static Monitor* _lock;
4365
4366 BoolObjectClosure* const _is_alive;
4367 const bool _unloading_occurred;
4368 const uint _num_workers;
4369
4370 // Variables used to claim nmethods.
4371 nmethod* _first_nmethod;
4372 volatile nmethod* _claimed_nmethod;
4373
4374 // The list of nmethods that need to be processed by the second pass.
4375 volatile nmethod* _postponed_list;
4376 volatile uint _num_entered_barrier;
4377
4378 public:
4379 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4380 _is_alive(is_alive),
4381 _unloading_occurred(unloading_occurred),
4382 _num_workers(num_workers),
4383 _first_nmethod(NULL),
4384 _claimed_nmethod(NULL),
4385 _postponed_list(NULL),
4386 _num_entered_barrier(0)
4387 {
4388 nmethod::increase_unloading_clock();
4389 // Get first alive nmethod
4390 NMethodIterator iter = NMethodIterator();
4391 if(iter.next_alive()) {
4392 _first_nmethod = iter.method();
4393 }
4394 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4395 }
4396
4397 ~G1CodeCacheUnloadingTask() {
4398 CodeCache::verify_clean_inline_caches();
4399
4400 CodeCache::set_needs_cache_clean(false);
4401 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4402
4403 CodeCache::verify_icholder_relocations();
4404 }
4405
4406 private:
4407 void add_to_postponed_list(nmethod* nm) {
4408 nmethod* old;
4409 do {
4410 old = (nmethod*)_postponed_list;
4411 nm->set_unloading_next(old);
4412 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4413 }
4414
4415 void clean_nmethod(nmethod* nm) {
4416 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4417
4418 if (postponed) {
4419 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4420 add_to_postponed_list(nm);
4421 }
4422
4423 // Mark that this thread has been cleaned/unloaded.
4424 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4425 nm->set_unloading_clock(nmethod::global_unloading_clock());
4426 }
4427
4428 void clean_nmethod_postponed(nmethod* nm) {
4429 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4430 }
4431
4432 static const int MaxClaimNmethods = 16;
4433
4434 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4435 nmethod* first;
4436 NMethodIterator last;
4437
4438 do {
4439 *num_claimed_nmethods = 0;
4440
4441 first = (nmethod*)_claimed_nmethod;
4442 last = NMethodIterator(first);
4443
4444 if (first != NULL) {
4445
4446 for (int i = 0; i < MaxClaimNmethods; i++) {
4447 if (!last.next_alive()) {
4448 break;
4449 }
4450 claimed_nmethods[i] = last.method();
4451 (*num_claimed_nmethods)++;
4452 }
4453 }
4454
4455 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4456 }
4457
4458 nmethod* claim_postponed_nmethod() {
4459 nmethod* claim;
4460 nmethod* next;
4461
4462 do {
4463 claim = (nmethod*)_postponed_list;
4464 if (claim == NULL) {
4465 return NULL;
4466 }
4467
4468 next = claim->unloading_next();
4469
4470 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4471
4472 return claim;
4473 }
4474
4475 public:
4476 // Mark that we're done with the first pass of nmethod cleaning.
4477 void barrier_mark(uint worker_id) {
4478 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4479 _num_entered_barrier++;
4480 if (_num_entered_barrier == _num_workers) {
4481 ml.notify_all();
4482 }
4483 }
4484
4485 // See if we have to wait for the other workers to
4486 // finish their first-pass nmethod cleaning work.
4487 void barrier_wait(uint worker_id) {
4488 if (_num_entered_barrier < _num_workers) {
4489 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4490 while (_num_entered_barrier < _num_workers) {
4491 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4492 }
4493 }
4494 }
4495
4496 // Cleaning and unloading of nmethods. Some work has to be postponed
4497 // to the second pass, when we know which nmethods survive.
4498 void work_first_pass(uint worker_id) {
4499 // The first nmethods is claimed by the first worker.
4500 if (worker_id == 0 && _first_nmethod != NULL) {
4501 clean_nmethod(_first_nmethod);
4502 _first_nmethod = NULL;
4503 }
4504
4505 int num_claimed_nmethods;
4506 nmethod* claimed_nmethods[MaxClaimNmethods];
4507
4508 while (true) {
4509 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4510
4511 if (num_claimed_nmethods == 0) {
4512 break;
4513 }
4514
4515 for (int i = 0; i < num_claimed_nmethods; i++) {
4516 clean_nmethod(claimed_nmethods[i]);
4517 }
4518 }
4519 }
4520
4521 void work_second_pass(uint worker_id) {
4522 nmethod* nm;
4523 // Take care of postponed nmethods.
4524 while ((nm = claim_postponed_nmethod()) != NULL) {
4525 clean_nmethod_postponed(nm);
4526 }
4527 }
4528 };
4529
4530 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4531
4532 class G1KlassCleaningTask : public StackObj {
4533 BoolObjectClosure* _is_alive;
4534 volatile jint _clean_klass_tree_claimed;
4535 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4536
4537 public:
4538 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4539 _is_alive(is_alive),
4540 _clean_klass_tree_claimed(0),
4541 _klass_iterator() {
4542 }
4543
4544 private:
4545 bool claim_clean_klass_tree_task() {
4546 if (_clean_klass_tree_claimed) {
4547 return false;
4548 }
4549
4550 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4551 }
4552
4553 InstanceKlass* claim_next_klass() {
4554 Klass* klass;
4555 do {
4556 klass =_klass_iterator.next_klass();
4557 } while (klass != NULL && !klass->is_instance_klass());
4558
4559 // this can be null so don't call InstanceKlass::cast
4560 return static_cast<InstanceKlass*>(klass);
4561 }
4562
4563 public:
4564
4565 void clean_klass(InstanceKlass* ik) {
4566 ik->clean_weak_instanceklass_links(_is_alive);
4567 }
4568
4569 void work() {
4570 ResourceMark rm;
4571
4572 // One worker will clean the subklass/sibling klass tree.
4573 if (claim_clean_klass_tree_task()) {
4574 Klass::clean_subklass_tree(_is_alive);
4575 }
4576
4577 // All workers will help cleaning the classes,
4578 InstanceKlass* klass;
4579 while ((klass = claim_next_klass()) != NULL) {
4580 clean_klass(klass);
4581 }
4582 }
4583 };
4584
4585 // To minimize the remark pause times, the tasks below are done in parallel.
4586 class G1ParallelCleaningTask : public AbstractGangTask {
4587 private:
4588 G1StringSymbolTableUnlinkTask _string_symbol_task;
4589 G1CodeCacheUnloadingTask _code_cache_task;
4590 G1KlassCleaningTask _klass_cleaning_task;
4591
4592 public:
4593 // The constructor is run in the VMThread.
4594 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4595 AbstractGangTask("Parallel Cleaning"),
4596 _string_symbol_task(is_alive, process_strings, process_symbols),
4597 _code_cache_task(num_workers, is_alive, unloading_occurred),
4598 _klass_cleaning_task(is_alive) {
4599 }
4600
4601 // The parallel work done by all worker threads.
4602 void work(uint worker_id) {
4603 // Do first pass of code cache cleaning.
4604 _code_cache_task.work_first_pass(worker_id);
4605
4606 // Let the threads mark that the first pass is done.
4607 _code_cache_task.barrier_mark(worker_id);
4608
4609 // Clean the Strings and Symbols.
4610 _string_symbol_task.work(worker_id);
4611
4612 // Wait for all workers to finish the first code cache cleaning pass.
4613 _code_cache_task.barrier_wait(worker_id);
4614
4615 // Do the second code cache cleaning work, which realize on
4616 // the liveness information gathered during the first pass.
4617 _code_cache_task.work_second_pass(worker_id);
4618
4619 // Clean all klasses that were not unloaded.
4620 _klass_cleaning_task.work();
4621 }
4622 };
4623
4624
4625 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4626 bool process_strings,
4627 bool process_symbols,
4628 bool class_unloading_occurred) {
4629 uint n_workers = workers()->active_workers();
4630
4631 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4632 n_workers, class_unloading_occurred);
4633 workers()->run_task(&g1_unlink_task);
4634 }
4635
4636 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4637 bool process_strings, bool process_symbols) {
4638 {
4639 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4640 workers()->run_task(&g1_unlink_task);
4641 }
4642
4643 if (G1StringDedup::is_enabled()) {
4644 G1StringDedup::unlink(is_alive);
4645 }
4646 }
4647
4648 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4649 private:
4650 DirtyCardQueueSet* _queue;
4651 public:
4652 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4653
4654 virtual void work(uint worker_id) {
4655 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4656 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4657
4658 RedirtyLoggedCardTableEntryClosure cl;
4659 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4660
4661 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4662 }
4663 };
4664
4665 void G1CollectedHeap::redirty_logged_cards() {
4666 double redirty_logged_cards_start = os::elapsedTime();
4667
4668 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4669 dirty_card_queue_set().reset_for_par_iteration();
4670 workers()->run_task(&redirty_task);
4671
4672 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4673 dcq.merge_bufferlists(&dirty_card_queue_set());
4674 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4675
4676 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4677 }
4678
4679 // Weak Reference Processing support
4680
4681 // An always "is_alive" closure that is used to preserve referents.
4682 // If the object is non-null then it's alive. Used in the preservation
4683 // of referent objects that are pointed to by reference objects
4684 // discovered by the CM ref processor.
4685 class G1AlwaysAliveClosure: public BoolObjectClosure {
4686 G1CollectedHeap* _g1;
4687 public:
4688 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4689 bool do_object_b(oop p) {
4690 if (p != NULL) {
4691 return true;
4692 }
4693 return false;
4694 }
4695 };
4696
4697 bool G1STWIsAliveClosure::do_object_b(oop p) {
4698 // An object is reachable if it is outside the collection set,
4699 // or is inside and copied.
4700 return !_g1->is_in_cset(p) || p->is_forwarded();
4701 }
4702
4703 // Non Copying Keep Alive closure
4704 class G1KeepAliveClosure: public OopClosure {
4705 G1CollectedHeap* _g1;
4706 public:
4707 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4708 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4709 void do_oop(oop* p) {
4710 oop obj = *p;
4711 assert(obj != NULL, "the caller should have filtered out NULL values");
4712
4713 const InCSetState cset_state = _g1->in_cset_state(obj);
4714 if (!cset_state.is_in_cset_or_humongous()) {
4715 return;
4716 }
4717 if (cset_state.is_in_cset()) {
4718 assert( obj->is_forwarded(), "invariant" );
4719 *p = obj->forwardee();
4720 } else {
4721 assert(!obj->is_forwarded(), "invariant" );
4722 assert(cset_state.is_humongous(),
4723 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4724 _g1->set_humongous_is_live(obj);
4725 }
4726 }
4727 };
4728
4729 // Copying Keep Alive closure - can be called from both
4730 // serial and parallel code as long as different worker
4731 // threads utilize different G1ParScanThreadState instances
4732 // and different queues.
4733
4734 class G1CopyingKeepAliveClosure: public OopClosure {
4735 G1CollectedHeap* _g1h;
4736 OopClosure* _copy_non_heap_obj_cl;
4737 G1ParScanThreadState* _par_scan_state;
4738
4739 public:
4740 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4741 OopClosure* non_heap_obj_cl,
4742 G1ParScanThreadState* pss):
4743 _g1h(g1h),
4744 _copy_non_heap_obj_cl(non_heap_obj_cl),
4745 _par_scan_state(pss)
4746 {}
4747
4748 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4749 virtual void do_oop( oop* p) { do_oop_work(p); }
4750
4751 template <class T> void do_oop_work(T* p) {
4752 oop obj = oopDesc::load_decode_heap_oop(p);
4753
4754 if (_g1h->is_in_cset_or_humongous(obj)) {
4755 // If the referent object has been forwarded (either copied
4756 // to a new location or to itself in the event of an
4757 // evacuation failure) then we need to update the reference
4758 // field and, if both reference and referent are in the G1
4759 // heap, update the RSet for the referent.
4760 //
4761 // If the referent has not been forwarded then we have to keep
4762 // it alive by policy. Therefore we have copy the referent.
4763 //
4764 // If the reference field is in the G1 heap then we can push
4765 // on the PSS queue. When the queue is drained (after each
4766 // phase of reference processing) the object and it's followers
4767 // will be copied, the reference field set to point to the
4768 // new location, and the RSet updated. Otherwise we need to
4769 // use the the non-heap or metadata closures directly to copy
4770 // the referent object and update the pointer, while avoiding
4771 // updating the RSet.
4772
4773 if (_g1h->is_in_g1_reserved(p)) {
4774 _par_scan_state->push_on_queue(p);
4775 } else {
4776 assert(!Metaspace::contains((const void*)p),
4777 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4778 _copy_non_heap_obj_cl->do_oop(p);
4779 }
4780 }
4781 }
4782 };
4783
4784 // Serial drain queue closure. Called as the 'complete_gc'
4785 // closure for each discovered list in some of the
4786 // reference processing phases.
4787
4788 class G1STWDrainQueueClosure: public VoidClosure {
4789 protected:
4790 G1CollectedHeap* _g1h;
4791 G1ParScanThreadState* _par_scan_state;
4792
4793 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4794
4795 public:
4796 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4797 _g1h(g1h),
4798 _par_scan_state(pss)
4799 { }
4800
4801 void do_void() {
4802 G1ParScanThreadState* const pss = par_scan_state();
4803 pss->trim_queue();
4804 }
4805 };
4806
4807 // Parallel Reference Processing closures
4808
4809 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4810 // processing during G1 evacuation pauses.
4811
4812 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4813 private:
4814 G1CollectedHeap* _g1h;
4815 G1ParScanThreadStateSet* _pss;
4816 RefToScanQueueSet* _queues;
4817 WorkGang* _workers;
4818 uint _active_workers;
4819
4820 public:
4821 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4822 G1ParScanThreadStateSet* per_thread_states,
4823 WorkGang* workers,
4824 RefToScanQueueSet *task_queues,
4825 uint n_workers) :
4826 _g1h(g1h),
4827 _pss(per_thread_states),
4828 _queues(task_queues),
4829 _workers(workers),
4830 _active_workers(n_workers)
4831 {
4832 assert(n_workers > 0, "shouldn't call this otherwise");
4833 }
4834
4835 // Executes the given task using concurrent marking worker threads.
4836 virtual void execute(ProcessTask& task);
4837 virtual void execute(EnqueueTask& task);
4838 };
4839
4840 // Gang task for possibly parallel reference processing
4841
4842 class G1STWRefProcTaskProxy: public AbstractGangTask {
4843 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4844 ProcessTask& _proc_task;
4845 G1CollectedHeap* _g1h;
4846 G1ParScanThreadStateSet* _pss;
4847 RefToScanQueueSet* _task_queues;
4848 ParallelTaskTerminator* _terminator;
4849
4850 public:
4851 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4852 G1CollectedHeap* g1h,
4853 G1ParScanThreadStateSet* per_thread_states,
4854 RefToScanQueueSet *task_queues,
4855 ParallelTaskTerminator* terminator) :
4856 AbstractGangTask("Process reference objects in parallel"),
4857 _proc_task(proc_task),
4858 _g1h(g1h),
4859 _pss(per_thread_states),
4860 _task_queues(task_queues),
4861 _terminator(terminator)
4862 {}
4863
4864 virtual void work(uint worker_id) {
4865 // The reference processing task executed by a single worker.
4866 ResourceMark rm;
4867 HandleMark hm;
4868
4869 G1STWIsAliveClosure is_alive(_g1h);
4870
4871 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4872 pss->set_ref_processor(NULL);
4873
4874 // Keep alive closure.
4875 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4876
4877 // Complete GC closure
4878 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4879
4880 // Call the reference processing task's work routine.
4881 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4882
4883 // Note we cannot assert that the refs array is empty here as not all
4884 // of the processing tasks (specifically phase2 - pp2_work) execute
4885 // the complete_gc closure (which ordinarily would drain the queue) so
4886 // the queue may not be empty.
4887 }
4888 };
4889
4890 // Driver routine for parallel reference processing.
4891 // Creates an instance of the ref processing gang
4892 // task and has the worker threads execute it.
4893 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4894 assert(_workers != NULL, "Need parallel worker threads.");
4895
4896 ParallelTaskTerminator terminator(_active_workers, _queues);
4897 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4898
4899 _workers->run_task(&proc_task_proxy);
4900 }
4901
4902 // Gang task for parallel reference enqueueing.
4903
4904 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4905 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4906 EnqueueTask& _enq_task;
4907
4908 public:
4909 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4910 AbstractGangTask("Enqueue reference objects in parallel"),
4911 _enq_task(enq_task)
4912 { }
4913
4914 virtual void work(uint worker_id) {
4915 _enq_task.work(worker_id);
4916 }
4917 };
4918
4919 // Driver routine for parallel reference enqueueing.
4920 // Creates an instance of the ref enqueueing gang
4921 // task and has the worker threads execute it.
4922
4923 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4924 assert(_workers != NULL, "Need parallel worker threads.");
4925
4926 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4927
4928 _workers->run_task(&enq_task_proxy);
4929 }
4930
4931 // End of weak reference support closures
4932
4933 // Abstract task used to preserve (i.e. copy) any referent objects
4934 // that are in the collection set and are pointed to by reference
4935 // objects discovered by the CM ref processor.
4936
4937 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4938 protected:
4939 G1CollectedHeap* _g1h;
4940 G1ParScanThreadStateSet* _pss;
4941 RefToScanQueueSet* _queues;
4942 ParallelTaskTerminator _terminator;
4943 uint _n_workers;
4944
4945 public:
4946 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4947 AbstractGangTask("ParPreserveCMReferents"),
4948 _g1h(g1h),
4949 _pss(per_thread_states),
4950 _queues(task_queues),
4951 _terminator(workers, _queues),
4952 _n_workers(workers)
4953 { }
4954
4955 void work(uint worker_id) {
4956 ResourceMark rm;
4957 HandleMark hm;
4958
4959 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4960 pss->set_ref_processor(NULL);
4961 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4962
4963 // Is alive closure
4964 G1AlwaysAliveClosure always_alive(_g1h);
4965
4966 // Copying keep alive closure. Applied to referent objects that need
4967 // to be copied.
4968 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4969
4970 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4971
4972 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4973 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4974
4975 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4976 // So this must be true - but assert just in case someone decides to
4977 // change the worker ids.
4978 assert(worker_id < limit, "sanity");
4979 assert(!rp->discovery_is_atomic(), "check this code");
4980
4981 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4982 for (uint idx = worker_id; idx < limit; idx += stride) {
4983 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4984
4985 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4986 while (iter.has_next()) {
4987 // Since discovery is not atomic for the CM ref processor, we
4988 // can see some null referent objects.
4989 iter.load_ptrs(DEBUG_ONLY(true));
4990 oop ref = iter.obj();
4991
4992 // This will filter nulls.
4993 if (iter.is_referent_alive()) {
4994 iter.make_referent_alive();
4995 }
4996 iter.move_to_next();
4997 }
4998 }
4999
5000 // Drain the queue - which may cause stealing
5001 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5002 drain_queue.do_void();
5003 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5004 assert(pss->queue_is_empty(), "should be");
5005 }
5006 };
5007
5008 // Weak Reference processing during an evacuation pause (part 1).
5009 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5010 double ref_proc_start = os::elapsedTime();
5011
5012 ReferenceProcessor* rp = _ref_processor_stw;
5013 assert(rp->discovery_enabled(), "should have been enabled");
5014
5015 // Any reference objects, in the collection set, that were 'discovered'
5016 // by the CM ref processor should have already been copied (either by
5017 // applying the external root copy closure to the discovered lists, or
5018 // by following an RSet entry).
5019 //
5020 // But some of the referents, that are in the collection set, that these
5021 // reference objects point to may not have been copied: the STW ref
5022 // processor would have seen that the reference object had already
5023 // been 'discovered' and would have skipped discovering the reference,
5024 // but would not have treated the reference object as a regular oop.
5025 // As a result the copy closure would not have been applied to the
5026 // referent object.
5027 //
5028 // We need to explicitly copy these referent objects - the references
5029 // will be processed at the end of remarking.
5030 //
5031 // We also need to do this copying before we process the reference
5032 // objects discovered by the STW ref processor in case one of these
5033 // referents points to another object which is also referenced by an
5034 // object discovered by the STW ref processor.
5035
5036 uint no_of_gc_workers = workers()->active_workers();
5037
5038 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5039 per_thread_states,
5040 no_of_gc_workers,
5041 _task_queues);
5042
5043 workers()->run_task(&keep_cm_referents);
5044
5045 // Closure to test whether a referent is alive.
5046 G1STWIsAliveClosure is_alive(this);
5047
5048 // Even when parallel reference processing is enabled, the processing
5049 // of JNI refs is serial and performed serially by the current thread
5050 // rather than by a worker. The following PSS will be used for processing
5051 // JNI refs.
5052
5053 // Use only a single queue for this PSS.
5054 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5055 pss->set_ref_processor(NULL);
5056 assert(pss->queue_is_empty(), "pre-condition");
5057
5058 // Keep alive closure.
5059 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5060
5061 // Serial Complete GC closure
5062 G1STWDrainQueueClosure drain_queue(this, pss);
5063
5064 // Setup the soft refs policy...
5065 rp->setup_policy(false);
5066
5067 ReferenceProcessorStats stats;
5068 if (!rp->processing_is_mt()) {
5069 // Serial reference processing...
5070 stats = rp->process_discovered_references(&is_alive,
5071 &keep_alive,
5072 &drain_queue,
5073 NULL,
5074 _gc_timer_stw);
5075 } else {
5076 // Parallel reference processing
5077 assert(rp->num_q() == no_of_gc_workers, "sanity");
5078 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5079
5080 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5081 stats = rp->process_discovered_references(&is_alive,
5082 &keep_alive,
5083 &drain_queue,
5084 &par_task_executor,
5085 _gc_timer_stw);
5086 }
5087
5088 _gc_tracer_stw->report_gc_reference_stats(stats);
5089
5090 // We have completed copying any necessary live referent objects.
5091 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5092
5093 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5094 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5095 }
5096
5097 // Weak Reference processing during an evacuation pause (part 2).
5098 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5099 double ref_enq_start = os::elapsedTime();
5100
5101 ReferenceProcessor* rp = _ref_processor_stw;
5102 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5103
5104 // Now enqueue any remaining on the discovered lists on to
5105 // the pending list.
5106 if (!rp->processing_is_mt()) {
5107 // Serial reference processing...
5108 rp->enqueue_discovered_references();
5109 } else {
5110 // Parallel reference enqueueing
5111
5112 uint n_workers = workers()->active_workers();
5113
5114 assert(rp->num_q() == n_workers, "sanity");
5115 assert(n_workers <= rp->max_num_q(), "sanity");
5116
5117 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5118 rp->enqueue_discovered_references(&par_task_executor);
5119 }
5120
5121 rp->verify_no_references_recorded();
5122 assert(!rp->discovery_enabled(), "should have been disabled");
5123
5124 // FIXME
5125 // CM's reference processing also cleans up the string and symbol tables.
5126 // Should we do that here also? We could, but it is a serial operation
5127 // and could significantly increase the pause time.
5128
5129 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5130 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5131 }
5132
5133 void G1CollectedHeap::pre_evacuate_collection_set() {
5134 _expand_heap_after_alloc_failure = true;
5135 _evacuation_failed = false;
5136
5137 // Disable the hot card cache.
5138 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5139 hot_card_cache->reset_hot_cache_claimed_index();
5140 hot_card_cache->set_use_cache(false);
5141
5142 }
5143
5144 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5145 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5146
5147 // Should G1EvacuationFailureALot be in effect for this GC?
5148 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5149
5150 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5151 double start_par_time_sec = os::elapsedTime();
5152 double end_par_time_sec;
5153
5154 {
5155 const uint n_workers = workers()->active_workers();
5156 G1RootProcessor root_processor(this, n_workers);
5157 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5158 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5159 if (collector_state()->during_initial_mark_pause()) {
5160 ClassLoaderDataGraph::clear_claimed_marks();
5161 }
5162
5163 // The individual threads will set their evac-failure closures.
5164 if (PrintTerminationStats) {
5165 print_termination_stats_hdr(gclog_or_tty);
5166 }
5167
5168 workers()->run_task(&g1_par_task);
5169 end_par_time_sec = os::elapsedTime();
5170
5171 // Closing the inner scope will execute the destructor
5172 // for the G1RootProcessor object. We record the current
5173 // elapsed time before closing the scope so that time
5174 // taken for the destructor is NOT included in the
5175 // reported parallel time.
5176 }
5177
5178 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5179
5180 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5181 phase_times->record_par_time(par_time_ms);
5182
5183 double code_root_fixup_time_ms =
5184 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5185 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5186
5187 // Process any discovered reference objects - we have
5188 // to do this _before_ we retire the GC alloc regions
5189 // as we may have to copy some 'reachable' referent
5190 // objects (and their reachable sub-graphs) that were
5191 // not copied during the pause.
5192 process_discovered_references(per_thread_states);
5193
5194 if (G1StringDedup::is_enabled()) {
5195 double fixup_start = os::elapsedTime();
5196
5197 G1STWIsAliveClosure is_alive(this);
5198 G1KeepAliveClosure keep_alive(this);
5199 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5200
5201 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5202 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5203 }
5204
5205 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5206
5207 if (evacuation_failed()) {
5208 remove_self_forwarding_pointers();
5209
5210 // Reset the G1EvacuationFailureALot counters and flags
5211 // Note: the values are reset only when an actual
5212 // evacuation failure occurs.
5213 NOT_PRODUCT(reset_evacuation_should_fail();)
5214 }
5215
5216 // Enqueue any remaining references remaining on the STW
5217 // reference processor's discovered lists. We need to do
5218 // this after the card table is cleaned (and verified) as
5219 // the act of enqueueing entries on to the pending list
5220 // will log these updates (and dirty their associated
5221 // cards). We need these updates logged to update any
5222 // RSets.
5223 enqueue_discovered_references(per_thread_states);
5224 }
5225
5226 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5227 _allocator->release_gc_alloc_regions(evacuation_info);
5228
5229 per_thread_states->flush();
5230
5231 record_obj_copy_mem_stats();
5232
5233 _survivor_evac_stats.adjust_desired_plab_sz();
5234 _old_evac_stats.adjust_desired_plab_sz();
5235
5236 // Reset and re-enable the hot card cache.
5237 // Note the counts for the cards in the regions in the
5238 // collection set are reset when the collection set is freed.
5239 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5240 hot_card_cache->reset_hot_cache();
5241 hot_card_cache->set_use_cache(true);
5242
5243 purge_code_root_memory();
5244
5245 redirty_logged_cards();
5246 #if defined(COMPILER2) || INCLUDE_JVMCI
5247 DerivedPointerTable::update_pointers();
5248 #endif
5249 }
5250
5251 void G1CollectedHeap::record_obj_copy_mem_stats() {
5252 g1_policy()->add_last_old_allocated_bytes(_old_evac_stats.allocated() * HeapWordSize);
5253
5254 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5255 create_g1_evac_summary(&_old_evac_stats));
5256 }
5257
5258 void G1CollectedHeap::free_region(HeapRegion* hr,
5259 FreeRegionList* free_list,
5260 bool par,
5261 bool locked) {
5262 assert(!hr->is_free(), "the region should not be free");
5263 assert(!hr->is_empty(), "the region should not be empty");
5264 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5265 assert(free_list != NULL, "pre-condition");
5266
5267 if (G1VerifyBitmaps) {
5268 MemRegion mr(hr->bottom(), hr->end());
5269 concurrent_mark()->clearRangePrevBitmap(mr);
5270 }
5271
5272 // Clear the card counts for this region.
5273 // Note: we only need to do this if the region is not young
5274 // (since we don't refine cards in young regions).
5275 if (!hr->is_young()) {
5276 _cg1r->hot_card_cache()->reset_card_counts(hr);
5277 }
5278 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5279 free_list->add_ordered(hr);
5280 }
5281
5282 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5283 FreeRegionList* free_list,
5284 bool par) {
5285 assert(hr->is_humongous(), "this is only for humongous regions");
5286 assert(free_list != NULL, "pre-condition");
5287 hr->clear_humongous();
5288 free_region(hr, free_list, par);
5289 }
5290
5291 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5292 const HeapRegionSetCount& humongous_regions_removed) {
5293 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5294 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5295 _old_set.bulk_remove(old_regions_removed);
5296 _humongous_set.bulk_remove(humongous_regions_removed);
5297 }
5298
5299 }
5300
5301 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5302 assert(list != NULL, "list can't be null");
5303 if (!list->is_empty()) {
5304 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5305 _hrm.insert_list_into_free_list(list);
5306 }
5307 }
5308
5309 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5310 decrease_used(bytes);
5311 }
5312
5313 class G1ParCleanupCTTask : public AbstractGangTask {
5314 G1SATBCardTableModRefBS* _ct_bs;
5315 G1CollectedHeap* _g1h;
5316 HeapRegion* volatile _su_head;
5317 public:
5318 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5319 G1CollectedHeap* g1h) :
5320 AbstractGangTask("G1 Par Cleanup CT Task"),
5321 _ct_bs(ct_bs), _g1h(g1h) { }
5322
5323 void work(uint worker_id) {
5324 HeapRegion* r;
5325 while (r = _g1h->pop_dirty_cards_region()) {
5326 clear_cards(r);
5327 }
5328 }
5329
5330 void clear_cards(HeapRegion* r) {
5331 // Cards of the survivors should have already been dirtied.
5332 if (!r->is_survivor()) {
5333 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5334 }
5335 }
5336 };
5337
5338 #ifndef PRODUCT
5339 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5340 G1CollectedHeap* _g1h;
5341 G1SATBCardTableModRefBS* _ct_bs;
5342 public:
5343 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5344 : _g1h(g1h), _ct_bs(ct_bs) { }
5345 virtual bool doHeapRegion(HeapRegion* r) {
5346 if (r->is_survivor()) {
5347 _g1h->verify_dirty_region(r);
5348 } else {
5349 _g1h->verify_not_dirty_region(r);
5350 }
5351 return false;
5352 }
5353 };
5354
5355 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5356 // All of the region should be clean.
5357 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5358 MemRegion mr(hr->bottom(), hr->end());
5359 ct_bs->verify_not_dirty_region(mr);
5360 }
5361
5362 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5363 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5364 // dirty allocated blocks as they allocate them. The thread that
5365 // retires each region and replaces it with a new one will do a
5366 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5367 // not dirty that area (one less thing to have to do while holding
5368 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5369 // is dirty.
5370 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5371 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5372 if (hr->is_young()) {
5373 ct_bs->verify_g1_young_region(mr);
5374 } else {
5375 ct_bs->verify_dirty_region(mr);
5376 }
5377 }
5378
5379 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5380 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5381 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5382 verify_dirty_region(hr);
5383 }
5384 }
5385
5386 void G1CollectedHeap::verify_dirty_young_regions() {
5387 verify_dirty_young_list(_young_list->first_region());
5388 }
5389
5390 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5391 HeapWord* tams, HeapWord* end) {
5392 guarantee(tams <= end,
5393 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5394 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5395 if (result < end) {
5396 gclog_or_tty->cr();
5397 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5398 bitmap_name, p2i(result));
5399 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5400 bitmap_name, p2i(tams), p2i(end));
5401 return false;
5402 }
5403 return true;
5404 }
5405
5406 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5407 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5408 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5409
5410 HeapWord* bottom = hr->bottom();
5411 HeapWord* ptams = hr->prev_top_at_mark_start();
5412 HeapWord* ntams = hr->next_top_at_mark_start();
5413 HeapWord* end = hr->end();
5414
5415 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5416
5417 bool res_n = true;
5418 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5419 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5420 // if we happen to be in that state.
5421 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5422 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5423 }
5424 if (!res_p || !res_n) {
5425 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5426 HR_FORMAT_PARAMS(hr));
5427 gclog_or_tty->print_cr("#### Caller: %s", caller);
5428 return false;
5429 }
5430 return true;
5431 }
5432
5433 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5434 if (!G1VerifyBitmaps) return;
5435
5436 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5437 }
5438
5439 class G1VerifyBitmapClosure : public HeapRegionClosure {
5440 private:
5441 const char* _caller;
5442 G1CollectedHeap* _g1h;
5443 bool _failures;
5444
5445 public:
5446 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5447 _caller(caller), _g1h(g1h), _failures(false) { }
5448
5449 bool failures() { return _failures; }
5450
5451 virtual bool doHeapRegion(HeapRegion* hr) {
5452 bool result = _g1h->verify_bitmaps(_caller, hr);
5453 if (!result) {
5454 _failures = true;
5455 }
5456 return false;
5457 }
5458 };
5459
5460 void G1CollectedHeap::check_bitmaps(const char* caller) {
5461 if (!G1VerifyBitmaps) return;
5462
5463 G1VerifyBitmapClosure cl(caller, this);
5464 heap_region_iterate(&cl);
5465 guarantee(!cl.failures(), "bitmap verification");
5466 }
5467
5468 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5469 private:
5470 bool _failures;
5471 public:
5472 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5473
5474 virtual bool doHeapRegion(HeapRegion* hr) {
5475 uint i = hr->hrm_index();
5476 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5477 if (hr->is_humongous()) {
5478 if (hr->in_collection_set()) {
5479 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5480 _failures = true;
5481 return true;
5482 }
5483 if (cset_state.is_in_cset()) {
5484 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5485 _failures = true;
5486 return true;
5487 }
5488 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5489 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5490 _failures = true;
5491 return true;
5492 }
5493 } else {
5494 if (cset_state.is_humongous()) {
5495 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5496 _failures = true;
5497 return true;
5498 }
5499 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5500 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5501 hr->in_collection_set(), cset_state.value(), i);
5502 _failures = true;
5503 return true;
5504 }
5505 if (cset_state.is_in_cset()) {
5506 if (hr->is_young() != (cset_state.is_young())) {
5507 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5508 hr->is_young(), cset_state.value(), i);
5509 _failures = true;
5510 return true;
5511 }
5512 if (hr->is_old() != (cset_state.is_old())) {
5513 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5514 hr->is_old(), cset_state.value(), i);
5515 _failures = true;
5516 return true;
5517 }
5518 }
5519 }
5520 return false;
5521 }
5522
5523 bool failures() const { return _failures; }
5524 };
5525
5526 bool G1CollectedHeap::check_cset_fast_test() {
5527 G1CheckCSetFastTableClosure cl;
5528 _hrm.iterate(&cl);
5529 return !cl.failures();
5530 }
5531 #endif // PRODUCT
5532
5533 void G1CollectedHeap::cleanUpCardTable() {
5534 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5535 double start = os::elapsedTime();
5536
5537 {
5538 // Iterate over the dirty cards region list.
5539 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5540
5541 workers()->run_task(&cleanup_task);
5542 #ifndef PRODUCT
5543 if (G1VerifyCTCleanup || VerifyAfterGC) {
5544 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5545 heap_region_iterate(&cleanup_verifier);
5546 }
5547 #endif
5548 }
5549
5550 double elapsed = os::elapsedTime() - start;
5551 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5552 }
5553
5554 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5555 size_t pre_used = 0;
5556 FreeRegionList local_free_list("Local List for CSet Freeing");
5557
5558 double young_time_ms = 0.0;
5559 double non_young_time_ms = 0.0;
5560
5561 // Since the collection set is a superset of the the young list,
5562 // all we need to do to clear the young list is clear its
5563 // head and length, and unlink any young regions in the code below
5564 _young_list->clear();
5565
5566 G1CollectorPolicy* policy = g1_policy();
5567
5568 double start_sec = os::elapsedTime();
5569 bool non_young = true;
5570
5571 HeapRegion* cur = cs_head;
5572 int age_bound = -1;
5573 size_t rs_lengths = 0;
5574
5575 while (cur != NULL) {
5576 assert(!is_on_master_free_list(cur), "sanity");
5577 if (non_young) {
5578 if (cur->is_young()) {
5579 double end_sec = os::elapsedTime();
5580 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5581 non_young_time_ms += elapsed_ms;
5582
5583 start_sec = os::elapsedTime();
5584 non_young = false;
5585 }
5586 } else {
5587 if (!cur->is_young()) {
5588 double end_sec = os::elapsedTime();
5589 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5590 young_time_ms += elapsed_ms;
5591
5592 start_sec = os::elapsedTime();
5593 non_young = true;
5594 }
5595 }
5596
5597 rs_lengths += cur->rem_set()->occupied_locked();
5598
5599 HeapRegion* next = cur->next_in_collection_set();
5600 assert(cur->in_collection_set(), "bad CS");
5601 cur->set_next_in_collection_set(NULL);
5602 clear_in_cset(cur);
5603
5604 if (cur->is_young()) {
5605 int index = cur->young_index_in_cset();
5606 assert(index != -1, "invariant");
5607 assert((uint) index < policy->young_cset_region_length(), "invariant");
5608 size_t words_survived = surviving_young_words[index];
5609 cur->record_surv_words_in_group(words_survived);
5610
5611 // At this point the we have 'popped' cur from the collection set
5612 // (linked via next_in_collection_set()) but it is still in the
5613 // young list (linked via next_young_region()). Clear the
5614 // _next_young_region field.
5615 cur->set_next_young_region(NULL);
5616 } else {
5617 int index = cur->young_index_in_cset();
5618 assert(index == -1, "invariant");
5619 }
5620
5621 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5622 (!cur->is_young() && cur->young_index_in_cset() == -1),
5623 "invariant" );
5624
5625 if (!cur->evacuation_failed()) {
5626 MemRegion used_mr = cur->used_region();
5627
5628 // And the region is empty.
5629 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5630 pre_used += cur->used();
5631 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5632 } else {
5633 cur->uninstall_surv_rate_group();
5634 if (cur->is_young()) {
5635 cur->set_young_index_in_cset(-1);
5636 }
5637 cur->set_evacuation_failed(false);
5638 // The region is now considered to be old.
5639 cur->set_old();
5640 // Do some allocation statistics accounting. Regions that failed evacuation
5641 // are always made old, so there is no need to update anything in the young
5642 // gen statistics, but we need to update old gen statistics.
5643 size_t used_words = cur->marked_bytes() / HeapWordSize;
5644 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5645 _old_set.add(cur);
5646 evacuation_info.increment_collectionset_used_after(cur->used());
5647 }
5648 cur = next;
5649 }
5650
5651 evacuation_info.set_regions_freed(local_free_list.length());
5652 policy->record_max_rs_lengths(rs_lengths);
5653 policy->cset_regions_freed();
5654
5655 double end_sec = os::elapsedTime();
5656 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5657
5658 if (non_young) {
5659 non_young_time_ms += elapsed_ms;
5660 } else {
5661 young_time_ms += elapsed_ms;
5662 }
5663
5664 prepend_to_freelist(&local_free_list);
5665 decrement_summary_bytes(pre_used);
5666 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5667 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5668 }
5669
5670 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5671 private:
5672 FreeRegionList* _free_region_list;
5673 HeapRegionSet* _proxy_set;
5674 HeapRegionSetCount _humongous_regions_removed;
5675 size_t _freed_bytes;
5676 public:
5677
5678 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5679 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5680 }
5681
5682 virtual bool doHeapRegion(HeapRegion* r) {
5683 if (!r->is_starts_humongous()) {
5684 return false;
5685 }
5686
5687 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5688
5689 oop obj = (oop)r->bottom();
5690 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5691
5692 // The following checks whether the humongous object is live are sufficient.
5693 // The main additional check (in addition to having a reference from the roots
5694 // or the young gen) is whether the humongous object has a remembered set entry.
5695 //
5696 // A humongous object cannot be live if there is no remembered set for it
5697 // because:
5698 // - there can be no references from within humongous starts regions referencing
5699 // the object because we never allocate other objects into them.
5700 // (I.e. there are no intra-region references that may be missed by the
5701 // remembered set)
5702 // - as soon there is a remembered set entry to the humongous starts region
5703 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5704 // until the end of a concurrent mark.
5705 //
5706 // It is not required to check whether the object has been found dead by marking
5707 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5708 // all objects allocated during that time are considered live.
5709 // SATB marking is even more conservative than the remembered set.
5710 // So if at this point in the collection there is no remembered set entry,
5711 // nobody has a reference to it.
5712 // At the start of collection we flush all refinement logs, and remembered sets
5713 // are completely up-to-date wrt to references to the humongous object.
5714 //
5715 // Other implementation considerations:
5716 // - never consider object arrays at this time because they would pose
5717 // considerable effort for cleaning up the the remembered sets. This is
5718 // required because stale remembered sets might reference locations that
5719 // are currently allocated into.
5720 uint region_idx = r->hrm_index();
5721 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5722 !r->rem_set()->is_empty()) {
5723
5724 if (G1TraceEagerReclaimHumongousObjects) {
5725 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",
5726 region_idx,
5727 (size_t)obj->size() * HeapWordSize,
5728 p2i(r->bottom()),
5729 r->rem_set()->occupied(),
5730 r->rem_set()->strong_code_roots_list_length(),
5731 next_bitmap->isMarked(r->bottom()),
5732 g1h->is_humongous_reclaim_candidate(region_idx),
5733 obj->is_typeArray()
5734 );
5735 }
5736
5737 return false;
5738 }
5739
5740 guarantee(obj->is_typeArray(),
5741 "Only eagerly reclaiming type arrays is supported, but the object "
5742 PTR_FORMAT " is not.", p2i(r->bottom()));
5743
5744 if (G1TraceEagerReclaimHumongousObjects) {
5745 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",
5746 region_idx,
5747 (size_t)obj->size() * HeapWordSize,
5748 p2i(r->bottom()),
5749 r->rem_set()->occupied(),
5750 r->rem_set()->strong_code_roots_list_length(),
5751 next_bitmap->isMarked(r->bottom()),
5752 g1h->is_humongous_reclaim_candidate(region_idx),
5753 obj->is_typeArray()
5754 );
5755 }
5756 // Need to clear mark bit of the humongous object if already set.
5757 if (next_bitmap->isMarked(r->bottom())) {
5758 next_bitmap->clear(r->bottom());
5759 }
5760 do {
5761 HeapRegion* next = g1h->next_region_in_humongous(r);
5762 _freed_bytes += r->used();
5763 r->set_containing_set(NULL);
5764 _humongous_regions_removed.increment(1u, r->capacity());
5765 g1h->free_humongous_region(r, _free_region_list, false);
5766 r = next;
5767 } while (r != NULL);
5768
5769 return false;
5770 }
5771
5772 HeapRegionSetCount& humongous_free_count() {
5773 return _humongous_regions_removed;
5774 }
5775
5776 size_t bytes_freed() const {
5777 return _freed_bytes;
5778 }
5779
5780 size_t humongous_reclaimed() const {
5781 return _humongous_regions_removed.length();
5782 }
5783 };
5784
5785 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5786 assert_at_safepoint(true);
5787
5788 if (!G1EagerReclaimHumongousObjects ||
5789 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5790 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5791 return;
5792 }
5793
5794 double start_time = os::elapsedTime();
5795
5796 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5797
5798 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5799 heap_region_iterate(&cl);
5800
5801 HeapRegionSetCount empty_set;
5802 remove_from_old_sets(empty_set, cl.humongous_free_count());
5803
5804 G1HRPrinter* hrp = hr_printer();
5805 if (hrp->is_active()) {
5806 FreeRegionListIterator iter(&local_cleanup_list);
5807 while (iter.more_available()) {
5808 HeapRegion* hr = iter.get_next();
5809 hrp->cleanup(hr);
5810 }
5811 }
5812
5813 prepend_to_freelist(&local_cleanup_list);
5814 decrement_summary_bytes(cl.bytes_freed());
5815
5816 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5817 cl.humongous_reclaimed());
5818 }
5819
5820 // This routine is similar to the above but does not record
5821 // any policy statistics or update free lists; we are abandoning
5822 // the current incremental collection set in preparation of a
5823 // full collection. After the full GC we will start to build up
5824 // the incremental collection set again.
5825 // This is only called when we're doing a full collection
5826 // and is immediately followed by the tearing down of the young list.
5827
5828 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5829 HeapRegion* cur = cs_head;
5830
5831 while (cur != NULL) {
5832 HeapRegion* next = cur->next_in_collection_set();
5833 assert(cur->in_collection_set(), "bad CS");
5834 cur->set_next_in_collection_set(NULL);
5835 clear_in_cset(cur);
5836 cur->set_young_index_in_cset(-1);
5837 cur = next;
5838 }
5839 }
5840
5841 void G1CollectedHeap::set_free_regions_coming() {
5842 if (G1ConcRegionFreeingVerbose) {
5843 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5844 "setting free regions coming");
5845 }
5846
5847 assert(!free_regions_coming(), "pre-condition");
5848 _free_regions_coming = true;
5849 }
5850
5851 void G1CollectedHeap::reset_free_regions_coming() {
5852 assert(free_regions_coming(), "pre-condition");
5853
5854 {
5855 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5856 _free_regions_coming = false;
5857 SecondaryFreeList_lock->notify_all();
5858 }
5859
5860 if (G1ConcRegionFreeingVerbose) {
5861 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5862 "reset free regions coming");
5863 }
5864 }
5865
5866 void G1CollectedHeap::wait_while_free_regions_coming() {
5867 // Most of the time we won't have to wait, so let's do a quick test
5868 // first before we take the lock.
5869 if (!free_regions_coming()) {
5870 return;
5871 }
5872
5873 if (G1ConcRegionFreeingVerbose) {
5874 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5875 "waiting for free regions");
5876 }
5877
5878 {
5879 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5880 while (free_regions_coming()) {
5881 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5882 }
5883 }
5884
5885 if (G1ConcRegionFreeingVerbose) {
5886 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5887 "done waiting for free regions");
5888 }
5889 }
5890
5891 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5892 return _allocator->is_retained_old_region(hr);
5893 }
5894
5895 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5896 _young_list->push_region(hr);
5897 }
5898
5899 class NoYoungRegionsClosure: public HeapRegionClosure {
5900 private:
5901 bool _success;
5902 public:
5903 NoYoungRegionsClosure() : _success(true) { }
5904 bool doHeapRegion(HeapRegion* r) {
5905 if (r->is_young()) {
5906 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5907 p2i(r->bottom()), p2i(r->end()));
5908 _success = false;
5909 }
5910 return false;
5911 }
5912 bool success() { return _success; }
5913 };
5914
5915 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5916 bool ret = _young_list->check_list_empty(check_sample);
5917
5918 if (check_heap) {
5919 NoYoungRegionsClosure closure;
5920 heap_region_iterate(&closure);
5921 ret = ret && closure.success();
5922 }
5923
5924 return ret;
5925 }
5926
5927 class TearDownRegionSetsClosure : public HeapRegionClosure {
5928 private:
5929 HeapRegionSet *_old_set;
5930
5931 public:
5932 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5933
5934 bool doHeapRegion(HeapRegion* r) {
5935 if (r->is_old()) {
5936 _old_set->remove(r);
5937 } else {
5938 // We ignore free regions, we'll empty the free list afterwards.
5939 // We ignore young regions, we'll empty the young list afterwards.
5940 // We ignore humongous regions, we're not tearing down the
5941 // humongous regions set.
5942 assert(r->is_free() || r->is_young() || r->is_humongous(),
5943 "it cannot be another type");
5944 }
5945 return false;
5946 }
5947
5948 ~TearDownRegionSetsClosure() {
5949 assert(_old_set->is_empty(), "post-condition");
5950 }
5951 };
5952
5953 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5954 assert_at_safepoint(true /* should_be_vm_thread */);
5955
5956 if (!free_list_only) {
5957 TearDownRegionSetsClosure cl(&_old_set);
5958 heap_region_iterate(&cl);
5959
5960 // Note that emptying the _young_list is postponed and instead done as
5961 // the first step when rebuilding the regions sets again. The reason for
5962 // this is that during a full GC string deduplication needs to know if
5963 // a collected region was young or old when the full GC was initiated.
5964 }
5965 _hrm.remove_all_free_regions();
5966 }
5967
5968 void G1CollectedHeap::increase_used(size_t bytes) {
5969 _summary_bytes_used += bytes;
5970 }
5971
5972 void G1CollectedHeap::decrease_used(size_t bytes) {
5973 assert(_summary_bytes_used >= bytes,
5974 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5975 _summary_bytes_used, bytes);
5976 _summary_bytes_used -= bytes;
5977 }
5978
5979 void G1CollectedHeap::set_used(size_t bytes) {
5980 _summary_bytes_used = bytes;
5981 }
5982
5983 class RebuildRegionSetsClosure : public HeapRegionClosure {
5984 private:
5985 bool _free_list_only;
5986 HeapRegionSet* _old_set;
5987 HeapRegionManager* _hrm;
5988 size_t _total_used;
5989
5990 public:
5991 RebuildRegionSetsClosure(bool free_list_only,
5992 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5993 _free_list_only(free_list_only),
5994 _old_set(old_set), _hrm(hrm), _total_used(0) {
5995 assert(_hrm->num_free_regions() == 0, "pre-condition");
5996 if (!free_list_only) {
5997 assert(_old_set->is_empty(), "pre-condition");
5998 }
5999 }
6000
6001 bool doHeapRegion(HeapRegion* r) {
6002 if (r->is_empty()) {
6003 // Add free regions to the free list
6004 r->set_free();
6005 r->set_allocation_context(AllocationContext::system());
6006 _hrm->insert_into_free_list(r);
6007 } else if (!_free_list_only) {
6008 assert(!r->is_young(), "we should not come across young regions");
6009
6010 if (r->is_humongous()) {
6011 // We ignore humongous regions. We left the humongous set unchanged.
6012 } else {
6013 // Objects that were compacted would have ended up on regions
6014 // that were previously old or free. Archive regions (which are
6015 // old) will not have been touched.
6016 assert(r->is_free() || r->is_old(), "invariant");
6017 // We now consider them old, so register as such. Leave
6018 // archive regions set that way, however, while still adding
6019 // them to the old set.
6020 if (!r->is_archive()) {
6021 r->set_old();
6022 }
6023 _old_set->add(r);
6024 }
6025 _total_used += r->used();
6026 }
6027
6028 return false;
6029 }
6030
6031 size_t total_used() {
6032 return _total_used;
6033 }
6034 };
6035
6036 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6037 assert_at_safepoint(true /* should_be_vm_thread */);
6038
6039 if (!free_list_only) {
6040 _young_list->empty_list();
6041 }
6042
6043 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6044 heap_region_iterate(&cl);
6045
6046 if (!free_list_only) {
6047 set_used(cl.total_used());
6048 if (_archive_allocator != NULL) {
6049 _archive_allocator->clear_used();
6050 }
6051 }
6052 assert(used_unlocked() == recalculate_used(),
6053 "inconsistent used_unlocked(), "
6054 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6055 used_unlocked(), recalculate_used());
6056 }
6057
6058 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6059 _refine_cte_cl->set_concurrent(concurrent);
6060 }
6061
6062 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6063 HeapRegion* hr = heap_region_containing(p);
6064 return hr->is_in(p);
6065 }
6066
6067 // Methods for the mutator alloc region
6068
6069 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6070 bool force) {
6071 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6072 assert(!force || g1_policy()->can_expand_young_list(),
6073 "if force is true we should be able to expand the young list");
6074 bool young_list_full = g1_policy()->is_young_list_full();
6075 if (force || !young_list_full) {
6076 HeapRegion* new_alloc_region = new_region(word_size,
6077 false /* is_old */,
6078 false /* do_expand */);
6079 if (new_alloc_region != NULL) {
6080 set_region_short_lived_locked(new_alloc_region);
6081 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6082 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6083 return new_alloc_region;
6084 }
6085 }
6086 return NULL;
6087 }
6088
6089 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6090 size_t allocated_bytes) {
6091 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6092 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6093
6094 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6095 increase_used(allocated_bytes);
6096 _hr_printer.retire(alloc_region);
6097 // We update the eden sizes here, when the region is retired,
6098 // instead of when it's allocated, since this is the point that its
6099 // used space has been recored in _summary_bytes_used.
6100 g1mm()->update_eden_size();
6101 }
6102
6103 // Methods for the GC alloc regions
6104
6105 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6106 uint count,
6107 InCSetState dest) {
6108 assert(FreeList_lock->owned_by_self(), "pre-condition");
6109
6110 if (count < g1_policy()->max_regions(dest)) {
6111 const bool is_survivor = (dest.is_young());
6112 HeapRegion* new_alloc_region = new_region(word_size,
6113 !is_survivor,
6114 true /* do_expand */);
6115 if (new_alloc_region != NULL) {
6116 // We really only need to do this for old regions given that we
6117 // should never scan survivors. But it doesn't hurt to do it
6118 // for survivors too.
6119 new_alloc_region->record_timestamp();
6120 if (is_survivor) {
6121 new_alloc_region->set_survivor();
6122 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6123 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6124 } else {
6125 new_alloc_region->set_old();
6126 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6127 check_bitmaps("Old Region Allocation", new_alloc_region);
6128 }
6129 bool during_im = collector_state()->during_initial_mark_pause();
6130 new_alloc_region->note_start_of_copying(during_im);
6131 return new_alloc_region;
6132 }
6133 }
6134 return NULL;
6135 }
6136
6137 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6138 size_t allocated_bytes,
6139 InCSetState dest) {
6140 bool during_im = collector_state()->during_initial_mark_pause();
6141 alloc_region->note_end_of_copying(during_im);
6142 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6143 if (dest.is_young()) {
6144 young_list()->add_survivor_region(alloc_region);
6145 } else {
6146 _old_set.add(alloc_region);
6147 }
6148 _hr_printer.retire(alloc_region);
6149 }
6150
6151 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6152 bool expanded = false;
6153 uint index = _hrm.find_highest_free(&expanded);
6154
6155 if (index != G1_NO_HRM_INDEX) {
6156 if (expanded) {
6157 ergo_verbose1(ErgoHeapSizing,
6158 "attempt heap expansion",
6159 ergo_format_reason("requested address range outside heap bounds")
6160 ergo_format_byte("region size"),
6161 HeapRegion::GrainWords * HeapWordSize);
6162 }
6163 _hrm.allocate_free_regions_starting_at(index, 1);
6164 return region_at(index);
6165 }
6166 return NULL;
6167 }
6168
6169 // Heap region set verification
6170
6171 class VerifyRegionListsClosure : public HeapRegionClosure {
6172 private:
6173 HeapRegionSet* _old_set;
6174 HeapRegionSet* _humongous_set;
6175 HeapRegionManager* _hrm;
6176
6177 public:
6178 HeapRegionSetCount _old_count;
6179 HeapRegionSetCount _humongous_count;
6180 HeapRegionSetCount _free_count;
6181
6182 VerifyRegionListsClosure(HeapRegionSet* old_set,
6183 HeapRegionSet* humongous_set,
6184 HeapRegionManager* hrm) :
6185 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6186 _old_count(), _humongous_count(), _free_count(){ }
6187
6188 bool doHeapRegion(HeapRegion* hr) {
6189 if (hr->is_young()) {
6190 // TODO
6191 } else if (hr->is_humongous()) {
6192 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6193 _humongous_count.increment(1u, hr->capacity());
6194 } else if (hr->is_empty()) {
6195 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6196 _free_count.increment(1u, hr->capacity());
6197 } else if (hr->is_old()) {
6198 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6199 _old_count.increment(1u, hr->capacity());
6200 } else {
6201 // There are no other valid region types. Check for one invalid
6202 // one we can identify: pinned without old or humongous set.
6203 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6204 ShouldNotReachHere();
6205 }
6206 return false;
6207 }
6208
6209 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6210 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6211 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6212 old_set->total_capacity_bytes(), _old_count.capacity());
6213
6214 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6215 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6216 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6217
6218 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());
6219 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6220 free_list->total_capacity_bytes(), _free_count.capacity());
6221 }
6222 };
6223
6224 void G1CollectedHeap::verify_region_sets() {
6225 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6226
6227 // First, check the explicit lists.
6228 _hrm.verify();
6229 {
6230 // Given that a concurrent operation might be adding regions to
6231 // the secondary free list we have to take the lock before
6232 // verifying it.
6233 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6234 _secondary_free_list.verify_list();
6235 }
6236
6237 // If a concurrent region freeing operation is in progress it will
6238 // be difficult to correctly attributed any free regions we come
6239 // across to the correct free list given that they might belong to
6240 // one of several (free_list, secondary_free_list, any local lists,
6241 // etc.). So, if that's the case we will skip the rest of the
6242 // verification operation. Alternatively, waiting for the concurrent
6243 // operation to complete will have a non-trivial effect on the GC's
6244 // operation (no concurrent operation will last longer than the
6245 // interval between two calls to verification) and it might hide
6246 // any issues that we would like to catch during testing.
6247 if (free_regions_coming()) {
6248 return;
6249 }
6250
6251 // Make sure we append the secondary_free_list on the free_list so
6252 // that all free regions we will come across can be safely
6253 // attributed to the free_list.
6254 append_secondary_free_list_if_not_empty_with_lock();
6255
6256 // Finally, make sure that the region accounting in the lists is
6257 // consistent with what we see in the heap.
6258
6259 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6260 heap_region_iterate(&cl);
6261 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6262 }
6263
6264 // Optimized nmethod scanning
6265
6266 class RegisterNMethodOopClosure: public OopClosure {
6267 G1CollectedHeap* _g1h;
6268 nmethod* _nm;
6269
6270 template <class T> void do_oop_work(T* p) {
6271 T heap_oop = oopDesc::load_heap_oop(p);
6272 if (!oopDesc::is_null(heap_oop)) {
6273 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6274 HeapRegion* hr = _g1h->heap_region_containing(obj);
6275 assert(!hr->is_continues_humongous(),
6276 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6277 " starting at " HR_FORMAT,
6278 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6279
6280 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6281 hr->add_strong_code_root_locked(_nm);
6282 }
6283 }
6284
6285 public:
6286 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6287 _g1h(g1h), _nm(nm) {}
6288
6289 void do_oop(oop* p) { do_oop_work(p); }
6290 void do_oop(narrowOop* p) { do_oop_work(p); }
6291 };
6292
6293 class UnregisterNMethodOopClosure: public OopClosure {
6294 G1CollectedHeap* _g1h;
6295 nmethod* _nm;
6296
6297 template <class T> void do_oop_work(T* p) {
6298 T heap_oop = oopDesc::load_heap_oop(p);
6299 if (!oopDesc::is_null(heap_oop)) {
6300 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6301 HeapRegion* hr = _g1h->heap_region_containing(obj);
6302 assert(!hr->is_continues_humongous(),
6303 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6304 " starting at " HR_FORMAT,
6305 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6306
6307 hr->remove_strong_code_root(_nm);
6308 }
6309 }
6310
6311 public:
6312 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6313 _g1h(g1h), _nm(nm) {}
6314
6315 void do_oop(oop* p) { do_oop_work(p); }
6316 void do_oop(narrowOop* p) { do_oop_work(p); }
6317 };
6318
6319 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6320 CollectedHeap::register_nmethod(nm);
6321
6322 guarantee(nm != NULL, "sanity");
6323 RegisterNMethodOopClosure reg_cl(this, nm);
6324 nm->oops_do(®_cl);
6325 }
6326
6327 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6328 CollectedHeap::unregister_nmethod(nm);
6329
6330 guarantee(nm != NULL, "sanity");
6331 UnregisterNMethodOopClosure reg_cl(this, nm);
6332 nm->oops_do(®_cl, true);
6333 }
6334
6335 void G1CollectedHeap::purge_code_root_memory() {
6336 double purge_start = os::elapsedTime();
6337 G1CodeRootSet::purge();
6338 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6339 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6340 }
6341
6342 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6343 G1CollectedHeap* _g1h;
6344
6345 public:
6346 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6347 _g1h(g1h) {}
6348
6349 void do_code_blob(CodeBlob* cb) {
6350 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6351 if (nm == NULL) {
6352 return;
6353 }
6354
6355 if (ScavengeRootsInCode) {
6356 _g1h->register_nmethod(nm);
6357 }
6358 }
6359 };
6360
6361 void G1CollectedHeap::rebuild_strong_code_roots() {
6362 RebuildStrongCodeRootClosure blob_cl(this);
6363 CodeCache::blobs_do(&blob_cl);
6364 }