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 if ((first + 1) == last) {
370 // the series has a single humongous region
371 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, obj_top);
372 } else {
373 // the series has more than one humongous regions
374 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, first_hr->end());
375 }
376 }
377
378 // Now, we will update the top fields of the "continues humongous"
379 // regions. The reason we need to do this is that, otherwise,
380 // these regions would look empty and this will confuse parts of
381 // G1. For example, the code that looks for a consecutive number
382 // of empty regions will consider them empty and try to
383 // re-allocate them. We can extend is_empty() to also include
384 // !is_continues_humongous(), but it is easier to just update the top
385 // fields here. The way we set top for all regions (i.e., top ==
386 // end for all regions but the last one, top == new_top for the
387 // last one) is actually used when we will free up the humongous
388 // region in free_humongous_region().
389 hr = NULL;
390 for (uint i = first + 1; i < last; ++i) {
391 hr = region_at(i);
392 if ((i + 1) == last) {
393 // last continues humongous region
394 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
395 "new_top should fall on this region");
396 hr->set_top(obj_top);
397 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, obj_top);
398 } else {
399 // not last one
400 assert(obj_top > hr->end(), "obj_top should be above this region");
401 hr->set_top(hr->end());
402 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
403 }
404 }
405 // If we have continues humongous regions (hr != NULL), its top should
406 // match obj_top.
407 assert(hr == NULL || (hr->top() == obj_top), "sanity");
408 check_bitmaps("Humongous Region Allocation", first_hr);
409
410 increase_used(word_size * HeapWordSize);
411
412 for (uint i = first; i < last; ++i) {
413 _humongous_set.add(region_at(i));
414 }
415
416 return new_obj;
417 }
418
419 // If could fit into free regions w/o expansion, try.
420 // Otherwise, if can expand, do so.
421 // Otherwise, if using ex regions might help, try with ex given back.
422 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
423 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
424
425 verify_region_sets_optional();
426
427 uint first = G1_NO_HRM_INDEX;
428 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
429
430 if (obj_regions == 1) {
431 // Only one region to allocate, try to use a fast path by directly allocating
432 // from the free lists. Do not try to expand here, we will potentially do that
433 // later.
434 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
435 if (hr != NULL) {
436 first = hr->hrm_index();
437 }
438 } else {
439 // We can't allocate humongous regions spanning more than one region while
440 // cleanupComplete() is running, since some of the regions we find to be
441 // empty might not yet be added to the free list. It is not straightforward
442 // to know in which list they are on so that we can remove them. We only
443 // need to do this if we need to allocate more than one region to satisfy the
444 // current humongous allocation request. If we are only allocating one region
445 // we use the one-region region allocation code (see above), that already
446 // potentially waits for regions from the secondary free list.
447 wait_while_free_regions_coming();
448 append_secondary_free_list_if_not_empty_with_lock();
449
450 // Policy: Try only empty regions (i.e. already committed first). Maybe we
451 // are lucky enough to find some.
452 first = _hrm.find_contiguous_only_empty(obj_regions);
453 if (first != G1_NO_HRM_INDEX) {
454 _hrm.allocate_free_regions_starting_at(first, obj_regions);
455 }
456 }
457
458 if (first == G1_NO_HRM_INDEX) {
459 // Policy: We could not find enough regions for the humongous object in the
460 // free list. Look through the heap to find a mix of free and uncommitted regions.
461 // If so, try expansion.
462 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
463 if (first != G1_NO_HRM_INDEX) {
464 // We found something. Make sure these regions are committed, i.e. expand
465 // the heap. Alternatively we could do a defragmentation GC.
466 ergo_verbose1(ErgoHeapSizing,
467 "attempt heap expansion",
468 ergo_format_reason("humongous allocation request failed")
469 ergo_format_byte("allocation request"),
470 word_size * HeapWordSize);
471
472 _hrm.expand_at(first, obj_regions);
473 g1_policy()->record_new_heap_size(num_regions());
474
475 #ifdef ASSERT
476 for (uint i = first; i < first + obj_regions; ++i) {
477 HeapRegion* hr = region_at(i);
478 assert(hr->is_free(), "sanity");
479 assert(hr->is_empty(), "sanity");
480 assert(is_on_master_free_list(hr), "sanity");
481 }
482 #endif
483 _hrm.allocate_free_regions_starting_at(first, obj_regions);
484 } else {
485 // Policy: Potentially trigger a defragmentation GC.
486 }
487 }
488
489 HeapWord* result = NULL;
490 if (first != G1_NO_HRM_INDEX) {
491 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
492 word_size, context);
493 assert(result != NULL, "it should always return a valid result");
494
495 // A successful humongous object allocation changes the used space
496 // information of the old generation so we need to recalculate the
497 // sizes and update the jstat counters here.
498 g1mm()->update_sizes();
499 }
500
501 verify_region_sets_optional();
502
503 return result;
504 }
505
506 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
507 assert_heap_not_locked_and_not_at_safepoint();
508 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
509
510 uint dummy_gc_count_before;
511 uint dummy_gclocker_retry_count = 0;
512 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
513 }
514
515 HeapWord*
516 G1CollectedHeap::mem_allocate(size_t word_size,
517 bool* gc_overhead_limit_was_exceeded) {
518 assert_heap_not_locked_and_not_at_safepoint();
519
520 // Loop until the allocation is satisfied, or unsatisfied after GC.
521 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
522 uint gc_count_before;
523
524 HeapWord* result = NULL;
525 if (!is_humongous(word_size)) {
526 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
527 } else {
528 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
529 }
530 if (result != NULL) {
531 return result;
532 }
533
534 // Create the garbage collection operation...
535 VM_G1CollectForAllocation op(gc_count_before, word_size);
536 op.set_allocation_context(AllocationContext::current());
537
538 // ...and get the VM thread to execute it.
539 VMThread::execute(&op);
540
541 if (op.prologue_succeeded() && op.pause_succeeded()) {
542 // If the operation was successful we'll return the result even
543 // if it is NULL. If the allocation attempt failed immediately
544 // after a Full GC, it's unlikely we'll be able to allocate now.
545 HeapWord* result = op.result();
546 if (result != NULL && !is_humongous(word_size)) {
547 // Allocations that take place on VM operations do not do any
548 // card dirtying and we have to do it here. We only have to do
549 // this for non-humongous allocations, though.
550 dirty_young_block(result, word_size);
551 }
552 return result;
553 } else {
554 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
555 return NULL;
556 }
557 assert(op.result() == NULL,
558 "the result should be NULL if the VM op did not succeed");
559 }
560
561 // Give a warning if we seem to be looping forever.
562 if ((QueuedAllocationWarningCount > 0) &&
563 (try_count % QueuedAllocationWarningCount == 0)) {
564 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
565 }
566 }
567
568 ShouldNotReachHere();
569 return NULL;
570 }
571
572 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
573 AllocationContext_t context,
574 uint* gc_count_before_ret,
575 uint* gclocker_retry_count_ret) {
576 // Make sure you read the note in attempt_allocation_humongous().
577
578 assert_heap_not_locked_and_not_at_safepoint();
579 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
580 "be called for humongous allocation requests");
581
582 // We should only get here after the first-level allocation attempt
583 // (attempt_allocation()) failed to allocate.
584
585 // We will loop until a) we manage to successfully perform the
586 // allocation or b) we successfully schedule a collection which
587 // fails to perform the allocation. b) is the only case when we'll
588 // return NULL.
589 HeapWord* result = NULL;
590 for (int try_count = 1; /* we'll return */; try_count += 1) {
591 bool should_try_gc;
592 uint gc_count_before;
593
594 {
595 MutexLockerEx x(Heap_lock);
596 result = _allocator->attempt_allocation_locked(word_size, context);
597 if (result != NULL) {
598 return result;
599 }
600
601 if (GC_locker::is_active_and_needs_gc()) {
602 if (g1_policy()->can_expand_young_list()) {
603 // No need for an ergo verbose message here,
604 // can_expand_young_list() does this when it returns true.
605 result = _allocator->attempt_allocation_force(word_size, context);
606 if (result != NULL) {
607 return result;
608 }
609 }
610 should_try_gc = false;
611 } else {
612 // The GCLocker may not be active but the GCLocker initiated
613 // GC may not yet have been performed (GCLocker::needs_gc()
614 // returns true). In this case we do not try this GC and
615 // wait until the GCLocker initiated GC is performed, and
616 // then retry the allocation.
617 if (GC_locker::needs_gc()) {
618 should_try_gc = false;
619 } else {
620 // Read the GC count while still holding the Heap_lock.
621 gc_count_before = total_collections();
622 should_try_gc = true;
623 }
624 }
625 }
626
627 if (should_try_gc) {
628 bool succeeded;
629 result = do_collection_pause(word_size, gc_count_before, &succeeded,
630 GCCause::_g1_inc_collection_pause);
631 if (result != NULL) {
632 assert(succeeded, "only way to get back a non-NULL result");
633 return result;
634 }
635
636 if (succeeded) {
637 // If we get here we successfully scheduled a collection which
638 // failed to allocate. No point in trying to allocate
639 // further. We'll just return NULL.
640 MutexLockerEx x(Heap_lock);
641 *gc_count_before_ret = total_collections();
642 return NULL;
643 }
644 } else {
645 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
646 MutexLockerEx x(Heap_lock);
647 *gc_count_before_ret = total_collections();
648 return NULL;
649 }
650 // The GCLocker is either active or the GCLocker initiated
651 // GC has not yet been performed. Stall until it is and
652 // then retry the allocation.
653 GC_locker::stall_until_clear();
654 (*gclocker_retry_count_ret) += 1;
655 }
656
657 // We can reach here if we were unsuccessful in scheduling a
658 // collection (because another thread beat us to it) or if we were
659 // stalled due to the GC locker. In either can we should retry the
660 // allocation attempt in case another thread successfully
661 // performed a collection and reclaimed enough space. We do the
662 // first attempt (without holding the Heap_lock) here and the
663 // follow-on attempt will be at the start of the next loop
664 // iteration (after taking the Heap_lock).
665 result = _allocator->attempt_allocation(word_size, context);
666 if (result != NULL) {
667 return result;
668 }
669
670 // Give a warning if we seem to be looping forever.
671 if ((QueuedAllocationWarningCount > 0) &&
672 (try_count % QueuedAllocationWarningCount == 0)) {
673 warning("G1CollectedHeap::attempt_allocation_slow() "
674 "retries %d times", try_count);
675 }
676 }
677
678 ShouldNotReachHere();
679 return NULL;
680 }
681
682 void G1CollectedHeap::begin_archive_alloc_range() {
683 assert_at_safepoint(true /* should_be_vm_thread */);
684 if (_archive_allocator == NULL) {
685 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
686 }
687 }
688
689 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
690 // Allocations in archive regions cannot be of a size that would be considered
691 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
692 // may be different at archive-restore time.
693 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
694 }
695
696 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
697 assert_at_safepoint(true /* should_be_vm_thread */);
698 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
699 if (is_archive_alloc_too_large(word_size)) {
700 return NULL;
701 }
702 return _archive_allocator->archive_mem_allocate(word_size);
703 }
704
705 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
706 size_t end_alignment_in_bytes) {
707 assert_at_safepoint(true /* should_be_vm_thread */);
708 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
709
710 // Call complete_archive to do the real work, filling in the MemRegion
711 // array with the archive regions.
712 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
713 delete _archive_allocator;
714 _archive_allocator = NULL;
715 }
716
717 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
718 assert(ranges != NULL, "MemRegion array NULL");
719 assert(count != 0, "No MemRegions provided");
720 MemRegion reserved = _hrm.reserved();
721 for (size_t i = 0; i < count; i++) {
722 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
723 return false;
724 }
725 }
726 return true;
727 }
728
729 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
730 assert(!is_init_completed(), "Expect to be called at JVM init time");
731 assert(ranges != NULL, "MemRegion array NULL");
732 assert(count != 0, "No MemRegions provided");
733 MutexLockerEx x(Heap_lock);
734
735 MemRegion reserved = _hrm.reserved();
736 HeapWord* prev_last_addr = NULL;
737 HeapRegion* prev_last_region = NULL;
738
739 // Temporarily disable pretouching of heap pages. This interface is used
740 // when mmap'ing archived heap data in, so pre-touching is wasted.
741 FlagSetting fs(AlwaysPreTouch, false);
742
743 // Enable archive object checking in G1MarkSweep. We have to let it know
744 // about each archive range, so that objects in those ranges aren't marked.
745 G1MarkSweep::enable_archive_object_check();
746
747 // For each specified MemRegion range, allocate the corresponding G1
748 // regions and mark them as archive regions. We expect the ranges in
749 // ascending starting address order, without overlap.
750 for (size_t i = 0; i < count; i++) {
751 MemRegion curr_range = ranges[i];
752 HeapWord* start_address = curr_range.start();
753 size_t word_size = curr_range.word_size();
754 HeapWord* last_address = curr_range.last();
755 size_t commits = 0;
756
757 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
758 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
759 p2i(start_address), p2i(last_address));
760 guarantee(start_address > prev_last_addr,
761 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
762 p2i(start_address), p2i(prev_last_addr));
763 prev_last_addr = last_address;
764
765 // Check for ranges that start in the same G1 region in which the previous
766 // range ended, and adjust the start address so we don't try to allocate
767 // the same region again. If the current range is entirely within that
768 // region, skip it, just adjusting the recorded top.
769 HeapRegion* start_region = _hrm.addr_to_region(start_address);
770 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
771 start_address = start_region->end();
772 if (start_address > last_address) {
773 increase_used(word_size * HeapWordSize);
774 start_region->set_top(last_address + 1);
775 continue;
776 }
777 start_region->set_top(start_address);
778 curr_range = MemRegion(start_address, last_address + 1);
779 start_region = _hrm.addr_to_region(start_address);
780 }
781
782 // Perform the actual region allocation, exiting if it fails.
783 // Then note how much new space we have allocated.
784 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
785 return false;
786 }
787 increase_used(word_size * HeapWordSize);
788 if (commits != 0) {
789 ergo_verbose1(ErgoHeapSizing,
790 "attempt heap expansion",
791 ergo_format_reason("allocate archive regions")
792 ergo_format_byte("total size"),
793 HeapRegion::GrainWords * HeapWordSize * commits);
794 }
795
796 // Mark each G1 region touched by the range as archive, add it to the old set,
797 // and set the allocation context and top.
798 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
799 HeapRegion* last_region = _hrm.addr_to_region(last_address);
800 prev_last_region = last_region;
801
802 while (curr_region != NULL) {
803 assert(curr_region->is_empty() && !curr_region->is_pinned(),
804 "Region already in use (index %u)", curr_region->hrm_index());
805 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
806 curr_region->set_allocation_context(AllocationContext::system());
807 curr_region->set_archive();
808 _old_set.add(curr_region);
809 if (curr_region != last_region) {
810 curr_region->set_top(curr_region->end());
811 curr_region = _hrm.next_region_in_heap(curr_region);
812 } else {
813 curr_region->set_top(last_address + 1);
814 curr_region = NULL;
815 }
816 }
817
818 // Notify mark-sweep of the archive range.
819 G1MarkSweep::set_range_archive(curr_range, true);
820 }
821 return true;
822 }
823
824 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
825 assert(!is_init_completed(), "Expect to be called at JVM init time");
826 assert(ranges != NULL, "MemRegion array NULL");
827 assert(count != 0, "No MemRegions provided");
828 MemRegion reserved = _hrm.reserved();
829 HeapWord *prev_last_addr = NULL;
830 HeapRegion* prev_last_region = NULL;
831
832 // For each MemRegion, create filler objects, if needed, in the G1 regions
833 // that contain the address range. The address range actually within the
834 // MemRegion will not be modified. That is assumed to have been initialized
835 // elsewhere, probably via an mmap of archived heap data.
836 MutexLockerEx x(Heap_lock);
837 for (size_t i = 0; i < count; i++) {
838 HeapWord* start_address = ranges[i].start();
839 HeapWord* last_address = ranges[i].last();
840
841 assert(reserved.contains(start_address) && reserved.contains(last_address),
842 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
843 p2i(start_address), p2i(last_address));
844 assert(start_address > prev_last_addr,
845 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
846 p2i(start_address), p2i(prev_last_addr));
847
848 HeapRegion* start_region = _hrm.addr_to_region(start_address);
849 HeapRegion* last_region = _hrm.addr_to_region(last_address);
850 HeapWord* bottom_address = start_region->bottom();
851
852 // Check for a range beginning in the same region in which the
853 // previous one ended.
854 if (start_region == prev_last_region) {
855 bottom_address = prev_last_addr + 1;
856 }
857
858 // Verify that the regions were all marked as archive regions by
859 // alloc_archive_regions.
860 HeapRegion* curr_region = start_region;
861 while (curr_region != NULL) {
862 guarantee(curr_region->is_archive(),
863 "Expected archive region at index %u", curr_region->hrm_index());
864 if (curr_region != last_region) {
865 curr_region = _hrm.next_region_in_heap(curr_region);
866 } else {
867 curr_region = NULL;
868 }
869 }
870
871 prev_last_addr = last_address;
872 prev_last_region = last_region;
873
874 // Fill the memory below the allocated range with dummy object(s),
875 // if the region bottom does not match the range start, or if the previous
876 // range ended within the same G1 region, and there is a gap.
877 if (start_address != bottom_address) {
878 size_t fill_size = pointer_delta(start_address, bottom_address);
879 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
880 increase_used(fill_size * HeapWordSize);
881 }
882 }
883 }
884
885 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
886 uint* gc_count_before_ret,
887 uint* gclocker_retry_count_ret) {
888 assert_heap_not_locked_and_not_at_safepoint();
889 assert(!is_humongous(word_size), "attempt_allocation() should not "
890 "be called for humongous allocation requests");
891
892 AllocationContext_t context = AllocationContext::current();
893 HeapWord* result = _allocator->attempt_allocation(word_size, context);
894
895 if (result == NULL) {
896 result = attempt_allocation_slow(word_size,
897 context,
898 gc_count_before_ret,
899 gclocker_retry_count_ret);
900 }
901 assert_heap_not_locked();
902 if (result != NULL) {
903 dirty_young_block(result, word_size);
904 }
905 return result;
906 }
907
908 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
909 assert(!is_init_completed(), "Expect to be called at JVM init time");
910 assert(ranges != NULL, "MemRegion array NULL");
911 assert(count != 0, "No MemRegions provided");
912 MemRegion reserved = _hrm.reserved();
913 HeapWord* prev_last_addr = NULL;
914 HeapRegion* prev_last_region = NULL;
915 size_t size_used = 0;
916 size_t uncommitted_regions = 0;
917
918 // For each Memregion, free the G1 regions that constitute it, and
919 // notify mark-sweep that the range is no longer to be considered 'archive.'
920 MutexLockerEx x(Heap_lock);
921 for (size_t i = 0; i < count; i++) {
922 HeapWord* start_address = ranges[i].start();
923 HeapWord* last_address = ranges[i].last();
924
925 assert(reserved.contains(start_address) && reserved.contains(last_address),
926 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
927 p2i(start_address), p2i(last_address));
928 assert(start_address > prev_last_addr,
929 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
930 p2i(start_address), p2i(prev_last_addr));
931 size_used += ranges[i].byte_size();
932 prev_last_addr = last_address;
933
934 HeapRegion* start_region = _hrm.addr_to_region(start_address);
935 HeapRegion* last_region = _hrm.addr_to_region(last_address);
936
937 // Check for ranges that start in the same G1 region in which the previous
938 // range ended, and adjust the start address so we don't try to free
939 // the same region again. If the current range is entirely within that
940 // region, skip it.
941 if (start_region == prev_last_region) {
942 start_address = start_region->end();
943 if (start_address > last_address) {
944 continue;
945 }
946 start_region = _hrm.addr_to_region(start_address);
947 }
948 prev_last_region = last_region;
949
950 // After verifying that each region was marked as an archive region by
951 // alloc_archive_regions, set it free and empty and uncommit it.
952 HeapRegion* curr_region = start_region;
953 while (curr_region != NULL) {
954 guarantee(curr_region->is_archive(),
955 "Expected archive region at index %u", curr_region->hrm_index());
956 uint curr_index = curr_region->hrm_index();
957 _old_set.remove(curr_region);
958 curr_region->set_free();
959 curr_region->set_top(curr_region->bottom());
960 if (curr_region != last_region) {
961 curr_region = _hrm.next_region_in_heap(curr_region);
962 } else {
963 curr_region = NULL;
964 }
965 _hrm.shrink_at(curr_index, 1);
966 uncommitted_regions++;
967 }
968
969 // Notify mark-sweep that this is no longer an archive range.
970 G1MarkSweep::set_range_archive(ranges[i], false);
971 }
972
973 if (uncommitted_regions != 0) {
974 ergo_verbose1(ErgoHeapSizing,
975 "attempt heap shrinking",
976 ergo_format_reason("uncommitted archive regions")
977 ergo_format_byte("total size"),
978 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
979 }
980 decrease_used(size_used);
981 }
982
983 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
984 uint* gc_count_before_ret,
985 uint* gclocker_retry_count_ret) {
986 // The structure of this method has a lot of similarities to
987 // attempt_allocation_slow(). The reason these two were not merged
988 // into a single one is that such a method would require several "if
989 // allocation is not humongous do this, otherwise do that"
990 // conditional paths which would obscure its flow. In fact, an early
991 // version of this code did use a unified method which was harder to
992 // follow and, as a result, it had subtle bugs that were hard to
993 // track down. So keeping these two methods separate allows each to
994 // be more readable. It will be good to keep these two in sync as
995 // much as possible.
996
997 assert_heap_not_locked_and_not_at_safepoint();
998 assert(is_humongous(word_size), "attempt_allocation_humongous() "
999 "should only be called for humongous allocations");
1000
1001 // Humongous objects can exhaust the heap quickly, so we should check if we
1002 // need to start a marking cycle at each humongous object allocation. We do
1003 // the check before we do the actual allocation. The reason for doing it
1004 // before the allocation is that we avoid having to keep track of the newly
1005 // allocated memory while we do a GC.
1006 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1007 word_size)) {
1008 collect(GCCause::_g1_humongous_allocation);
1009 }
1010
1011 // We will loop until a) we manage to successfully perform the
1012 // allocation or b) we successfully schedule a collection which
1013 // fails to perform the allocation. b) is the only case when we'll
1014 // return NULL.
1015 HeapWord* result = NULL;
1016 for (int try_count = 1; /* we'll return */; try_count += 1) {
1017 bool should_try_gc;
1018 uint gc_count_before;
1019
1020 {
1021 MutexLockerEx x(Heap_lock);
1022
1023 // Given that humongous objects are not allocated in young
1024 // regions, we'll first try to do the allocation without doing a
1025 // collection hoping that there's enough space in the heap.
1026 result = humongous_obj_allocate(word_size, AllocationContext::current());
1027 if (result != NULL) {
1028 return result;
1029 }
1030
1031 if (GC_locker::is_active_and_needs_gc()) {
1032 should_try_gc = false;
1033 } else {
1034 // The GCLocker may not be active but the GCLocker initiated
1035 // GC may not yet have been performed (GCLocker::needs_gc()
1036 // returns true). In this case we do not try this GC and
1037 // wait until the GCLocker initiated GC is performed, and
1038 // then retry the allocation.
1039 if (GC_locker::needs_gc()) {
1040 should_try_gc = false;
1041 } else {
1042 // Read the GC count while still holding the Heap_lock.
1043 gc_count_before = total_collections();
1044 should_try_gc = true;
1045 }
1046 }
1047 }
1048
1049 if (should_try_gc) {
1050 // If we failed to allocate the humongous object, we should try to
1051 // do a collection pause (if we're allowed) in case it reclaims
1052 // enough space for the allocation to succeed after the pause.
1053
1054 bool succeeded;
1055 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1056 GCCause::_g1_humongous_allocation);
1057 if (result != NULL) {
1058 assert(succeeded, "only way to get back a non-NULL result");
1059 return result;
1060 }
1061
1062 if (succeeded) {
1063 // If we get here we successfully scheduled a collection which
1064 // failed to allocate. No point in trying to allocate
1065 // further. We'll just return NULL.
1066 MutexLockerEx x(Heap_lock);
1067 *gc_count_before_ret = total_collections();
1068 return NULL;
1069 }
1070 } else {
1071 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1072 MutexLockerEx x(Heap_lock);
1073 *gc_count_before_ret = total_collections();
1074 return NULL;
1075 }
1076 // The GCLocker is either active or the GCLocker initiated
1077 // GC has not yet been performed. Stall until it is and
1078 // then retry the allocation.
1079 GC_locker::stall_until_clear();
1080 (*gclocker_retry_count_ret) += 1;
1081 }
1082
1083 // We can reach here if we were unsuccessful in scheduling a
1084 // collection (because another thread beat us to it) or if we were
1085 // stalled due to the GC locker. In either can we should retry the
1086 // allocation attempt in case another thread successfully
1087 // performed a collection and reclaimed enough space. Give a
1088 // warning if we seem to be looping forever.
1089
1090 if ((QueuedAllocationWarningCount > 0) &&
1091 (try_count % QueuedAllocationWarningCount == 0)) {
1092 warning("G1CollectedHeap::attempt_allocation_humongous() "
1093 "retries %d times", try_count);
1094 }
1095 }
1096
1097 ShouldNotReachHere();
1098 return NULL;
1099 }
1100
1101 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1102 AllocationContext_t context,
1103 bool expect_null_mutator_alloc_region) {
1104 assert_at_safepoint(true /* should_be_vm_thread */);
1105 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1106 "the current alloc region was unexpectedly found to be non-NULL");
1107
1108 if (!is_humongous(word_size)) {
1109 return _allocator->attempt_allocation_locked(word_size, context);
1110 } else {
1111 HeapWord* result = humongous_obj_allocate(word_size, context);
1112 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1113 collector_state()->set_initiate_conc_mark_if_possible(true);
1114 }
1115 return result;
1116 }
1117
1118 ShouldNotReachHere();
1119 }
1120
1121 class PostMCRemSetClearClosure: public HeapRegionClosure {
1122 G1CollectedHeap* _g1h;
1123 ModRefBarrierSet* _mr_bs;
1124 public:
1125 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1126 _g1h(g1h), _mr_bs(mr_bs) {}
1127
1128 bool doHeapRegion(HeapRegion* r) {
1129 HeapRegionRemSet* hrrs = r->rem_set();
1130
1131 _g1h->reset_gc_time_stamps(r);
1132
1133 if (r->is_continues_humongous()) {
1134 // We'll assert that the strong code root list and RSet is empty
1135 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1136 assert(hrrs->occupied() == 0, "RSet should be empty");
1137 return false;
1138 }
1139
1140 hrrs->clear();
1141 // You might think here that we could clear just the cards
1142 // corresponding to the used region. But no: if we leave a dirty card
1143 // in a region we might allocate into, then it would prevent that card
1144 // from being enqueued, and cause it to be missed.
1145 // Re: the performance cost: we shouldn't be doing full GC anyway!
1146 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1147
1148 return false;
1149 }
1150 };
1151
1152 void G1CollectedHeap::clear_rsets_post_compaction() {
1153 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1154 heap_region_iterate(&rs_clear);
1155 }
1156
1157 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1158 G1CollectedHeap* _g1h;
1159 UpdateRSOopClosure _cl;
1160 public:
1161 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1162 _cl(g1->g1_rem_set(), worker_i),
1163 _g1h(g1)
1164 { }
1165
1166 bool doHeapRegion(HeapRegion* r) {
1167 if (!r->is_continues_humongous()) {
1168 _cl.set_from(r);
1169 r->oop_iterate(&_cl);
1170 }
1171 return false;
1172 }
1173 };
1174
1175 class ParRebuildRSTask: public AbstractGangTask {
1176 G1CollectedHeap* _g1;
1177 HeapRegionClaimer _hrclaimer;
1178
1179 public:
1180 ParRebuildRSTask(G1CollectedHeap* g1) :
1181 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1182
1183 void work(uint worker_id) {
1184 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1185 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1186 }
1187 };
1188
1189 class PostCompactionPrinterClosure: public HeapRegionClosure {
1190 private:
1191 G1HRPrinter* _hr_printer;
1192 public:
1193 bool doHeapRegion(HeapRegion* hr) {
1194 assert(!hr->is_young(), "not expecting to find young regions");
1195 if (hr->is_free()) {
1196 // We only generate output for non-empty regions.
1197 } else if (hr->is_starts_humongous()) {
1198 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1199 } else if (hr->is_continues_humongous()) {
1200 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1201 } else if (hr->is_archive()) {
1202 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1203 } else if (hr->is_old()) {
1204 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1205 } else {
1206 ShouldNotReachHere();
1207 }
1208 return false;
1209 }
1210
1211 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1212 : _hr_printer(hr_printer) { }
1213 };
1214
1215 void G1CollectedHeap::print_hrm_post_compaction() {
1216 PostCompactionPrinterClosure cl(hr_printer());
1217 heap_region_iterate(&cl);
1218 }
1219
1220 bool G1CollectedHeap::do_collection(bool explicit_gc,
1221 bool clear_all_soft_refs,
1222 size_t word_size) {
1223 assert_at_safepoint(true /* should_be_vm_thread */);
1224
1225 if (GC_locker::check_active_before_gc()) {
1226 return false;
1227 }
1228
1229 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1230 gc_timer->register_gc_start();
1231
1232 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1233 GCIdMark gc_id_mark;
1234 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1235
1236 SvcGCMarker sgcm(SvcGCMarker::FULL);
1237 ResourceMark rm;
1238
1239 G1Log::update_level();
1240 print_heap_before_gc();
1241 trace_heap_before_gc(gc_tracer);
1242
1243 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1244
1245 verify_region_sets_optional();
1246
1247 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1248 collector_policy()->should_clear_all_soft_refs();
1249
1250 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1251
1252 {
1253 IsGCActiveMark x;
1254
1255 // Timing
1256 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1257 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1258
1259 {
1260 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1261 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1262 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1263
1264 g1_policy()->record_full_collection_start();
1265
1266 // Note: When we have a more flexible GC logging framework that
1267 // allows us to add optional attributes to a GC log record we
1268 // could consider timing and reporting how long we wait in the
1269 // following two methods.
1270 wait_while_free_regions_coming();
1271 // If we start the compaction before the CM threads finish
1272 // scanning the root regions we might trip them over as we'll
1273 // be moving objects / updating references. So let's wait until
1274 // they are done. By telling them to abort, they should complete
1275 // early.
1276 _cm->root_regions()->abort();
1277 _cm->root_regions()->wait_until_scan_finished();
1278 append_secondary_free_list_if_not_empty_with_lock();
1279
1280 gc_prologue(true);
1281 increment_total_collections(true /* full gc */);
1282 increment_old_marking_cycles_started();
1283
1284 assert(used() == recalculate_used(), "Should be equal");
1285
1286 verify_before_gc();
1287
1288 check_bitmaps("Full GC Start");
1289 pre_full_gc_dump(gc_timer);
1290
1291 #if defined(COMPILER2) || INCLUDE_JVMCI
1292 DerivedPointerTable::clear();
1293 #endif
1294
1295 // Disable discovery and empty the discovered lists
1296 // for the CM ref processor.
1297 ref_processor_cm()->disable_discovery();
1298 ref_processor_cm()->abandon_partial_discovery();
1299 ref_processor_cm()->verify_no_references_recorded();
1300
1301 // Abandon current iterations of concurrent marking and concurrent
1302 // refinement, if any are in progress. We have to do this before
1303 // wait_until_scan_finished() below.
1304 concurrent_mark()->abort();
1305
1306 // Make sure we'll choose a new allocation region afterwards.
1307 _allocator->release_mutator_alloc_region();
1308 _allocator->abandon_gc_alloc_regions();
1309 g1_rem_set()->cleanupHRRS();
1310
1311 // We should call this after we retire any currently active alloc
1312 // regions so that all the ALLOC / RETIRE events are generated
1313 // before the start GC event.
1314 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1315
1316 // We may have added regions to the current incremental collection
1317 // set between the last GC or pause and now. We need to clear the
1318 // incremental collection set and then start rebuilding it afresh
1319 // after this full GC.
1320 abandon_collection_set(g1_policy()->inc_cset_head());
1321 g1_policy()->clear_incremental_cset();
1322 g1_policy()->stop_incremental_cset_building();
1323
1324 tear_down_region_sets(false /* free_list_only */);
1325 collector_state()->set_gcs_are_young(true);
1326
1327 // See the comments in g1CollectedHeap.hpp and
1328 // G1CollectedHeap::ref_processing_init() about
1329 // how reference processing currently works in G1.
1330
1331 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1332 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1333
1334 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1335 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1336
1337 ref_processor_stw()->enable_discovery();
1338 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1339
1340 // Do collection work
1341 {
1342 HandleMark hm; // Discard invalid handles created during gc
1343 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1344 }
1345
1346 assert(num_free_regions() == 0, "we should not have added any free regions");
1347 rebuild_region_sets(false /* free_list_only */);
1348
1349 // Enqueue any discovered reference objects that have
1350 // not been removed from the discovered lists.
1351 ref_processor_stw()->enqueue_discovered_references();
1352
1353 #if defined(COMPILER2) || INCLUDE_JVMCI
1354 DerivedPointerTable::update_pointers();
1355 #endif
1356
1357 MemoryService::track_memory_usage();
1358
1359 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1360 ref_processor_stw()->verify_no_references_recorded();
1361
1362 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1363 ClassLoaderDataGraph::purge();
1364 MetaspaceAux::verify_metrics();
1365
1366 // Note: since we've just done a full GC, concurrent
1367 // marking is no longer active. Therefore we need not
1368 // re-enable reference discovery for the CM ref processor.
1369 // That will be done at the start of the next marking cycle.
1370 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1371 ref_processor_cm()->verify_no_references_recorded();
1372
1373 reset_gc_time_stamp();
1374 // Since everything potentially moved, we will clear all remembered
1375 // sets, and clear all cards. Later we will rebuild remembered
1376 // sets. We will also reset the GC time stamps of the regions.
1377 clear_rsets_post_compaction();
1378 check_gc_time_stamps();
1379
1380 // Resize the heap if necessary.
1381 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1382
1383 if (_hr_printer.is_active()) {
1384 // We should do this after we potentially resize the heap so
1385 // that all the COMMIT / UNCOMMIT events are generated before
1386 // the end GC event.
1387
1388 print_hrm_post_compaction();
1389 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1390 }
1391
1392 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1393 if (hot_card_cache->use_cache()) {
1394 hot_card_cache->reset_card_counts();
1395 hot_card_cache->reset_hot_cache();
1396 }
1397
1398 // Rebuild remembered sets of all regions.
1399 uint n_workers =
1400 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1401 workers()->active_workers(),
1402 Threads::number_of_non_daemon_threads());
1403 workers()->set_active_workers(n_workers);
1404
1405 ParRebuildRSTask rebuild_rs_task(this);
1406 workers()->run_task(&rebuild_rs_task);
1407
1408 // Rebuild the strong code root lists for each region
1409 rebuild_strong_code_roots();
1410
1411 if (true) { // FIXME
1412 MetaspaceGC::compute_new_size();
1413 }
1414
1415 #ifdef TRACESPINNING
1416 ParallelTaskTerminator::print_termination_counts();
1417 #endif
1418
1419 // Discard all rset updates
1420 JavaThread::dirty_card_queue_set().abandon_logs();
1421 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1422
1423 _young_list->reset_sampled_info();
1424 // At this point there should be no regions in the
1425 // entire heap tagged as young.
1426 assert(check_young_list_empty(true /* check_heap */),
1427 "young list should be empty at this point");
1428
1429 // Update the number of full collections that have been completed.
1430 increment_old_marking_cycles_completed(false /* concurrent */);
1431
1432 _hrm.verify_optional();
1433 verify_region_sets_optional();
1434
1435 verify_after_gc();
1436
1437 // Clear the previous marking bitmap, if needed for bitmap verification.
1438 // Note we cannot do this when we clear the next marking bitmap in
1439 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1440 // objects marked during a full GC against the previous bitmap.
1441 // But we need to clear it before calling check_bitmaps below since
1442 // the full GC has compacted objects and updated TAMS but not updated
1443 // the prev bitmap.
1444 if (G1VerifyBitmaps) {
1445 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1446 }
1447 check_bitmaps("Full GC End");
1448
1449 // Start a new incremental collection set for the next pause
1450 assert(g1_policy()->collection_set() == NULL, "must be");
1451 g1_policy()->start_incremental_cset_building();
1452
1453 clear_cset_fast_test();
1454
1455 _allocator->init_mutator_alloc_region();
1456
1457 g1_policy()->record_full_collection_end();
1458
1459 if (G1Log::fine()) {
1460 g1_policy()->print_heap_transition();
1461 }
1462
1463 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1464 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1465 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1466 // before any GC notifications are raised.
1467 g1mm()->update_sizes();
1468
1469 gc_epilogue(true);
1470 }
1471
1472 if (G1Log::finer()) {
1473 g1_policy()->print_detailed_heap_transition(true /* full */);
1474 }
1475
1476 print_heap_after_gc();
1477 trace_heap_after_gc(gc_tracer);
1478
1479 post_full_gc_dump(gc_timer);
1480
1481 gc_timer->register_gc_end();
1482 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1483 }
1484
1485 return true;
1486 }
1487
1488 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1489 // do_collection() will return whether it succeeded in performing
1490 // the GC. Currently, there is no facility on the
1491 // do_full_collection() API to notify the caller than the collection
1492 // did not succeed (e.g., because it was locked out by the GC
1493 // locker). So, right now, we'll ignore the return value.
1494 bool dummy = do_collection(true, /* explicit_gc */
1495 clear_all_soft_refs,
1496 0 /* word_size */);
1497 }
1498
1499 // This code is mostly copied from TenuredGeneration.
1500 void
1501 G1CollectedHeap::
1502 resize_if_necessary_after_full_collection(size_t word_size) {
1503 // Include the current allocation, if any, and bytes that will be
1504 // pre-allocated to support collections, as "used".
1505 const size_t used_after_gc = used();
1506 const size_t capacity_after_gc = capacity();
1507 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1508
1509 // This is enforced in arguments.cpp.
1510 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1511 "otherwise the code below doesn't make sense");
1512
1513 // We don't have floating point command-line arguments
1514 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1515 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1516 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1517 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1518
1519 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1520 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1521
1522 // We have to be careful here as these two calculations can overflow
1523 // 32-bit size_t's.
1524 double used_after_gc_d = (double) used_after_gc;
1525 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1526 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1527
1528 // Let's make sure that they are both under the max heap size, which
1529 // by default will make them fit into a size_t.
1530 double desired_capacity_upper_bound = (double) max_heap_size;
1531 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1532 desired_capacity_upper_bound);
1533 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1534 desired_capacity_upper_bound);
1535
1536 // We can now safely turn them into size_t's.
1537 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1538 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1539
1540 // This assert only makes sense here, before we adjust them
1541 // with respect to the min and max heap size.
1542 assert(minimum_desired_capacity <= maximum_desired_capacity,
1543 "minimum_desired_capacity = " SIZE_FORMAT ", "
1544 "maximum_desired_capacity = " SIZE_FORMAT,
1545 minimum_desired_capacity, maximum_desired_capacity);
1546
1547 // Should not be greater than the heap max size. No need to adjust
1548 // it with respect to the heap min size as it's a lower bound (i.e.,
1549 // we'll try to make the capacity larger than it, not smaller).
1550 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1551 // Should not be less than the heap min size. No need to adjust it
1552 // with respect to the heap max size as it's an upper bound (i.e.,
1553 // we'll try to make the capacity smaller than it, not greater).
1554 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1555
1556 if (capacity_after_gc < minimum_desired_capacity) {
1557 // Don't expand unless it's significant
1558 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1559 ergo_verbose4(ErgoHeapSizing,
1560 "attempt heap expansion",
1561 ergo_format_reason("capacity lower than "
1562 "min desired capacity after Full GC")
1563 ergo_format_byte("capacity")
1564 ergo_format_byte("occupancy")
1565 ergo_format_byte_perc("min desired capacity"),
1566 capacity_after_gc, used_after_gc,
1567 minimum_desired_capacity, (double) MinHeapFreeRatio);
1568 expand(expand_bytes);
1569
1570 // No expansion, now see if we want to shrink
1571 } else if (capacity_after_gc > maximum_desired_capacity) {
1572 // Capacity too large, compute shrinking size
1573 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1574 ergo_verbose4(ErgoHeapSizing,
1575 "attempt heap shrinking",
1576 ergo_format_reason("capacity higher than "
1577 "max desired capacity after Full GC")
1578 ergo_format_byte("capacity")
1579 ergo_format_byte("occupancy")
1580 ergo_format_byte_perc("max desired capacity"),
1581 capacity_after_gc, used_after_gc,
1582 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1583 shrink(shrink_bytes);
1584 }
1585 }
1586
1587 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1588 AllocationContext_t context,
1589 bool do_gc,
1590 bool clear_all_soft_refs,
1591 bool expect_null_mutator_alloc_region,
1592 bool* gc_succeeded) {
1593 *gc_succeeded = true;
1594 // Let's attempt the allocation first.
1595 HeapWord* result =
1596 attempt_allocation_at_safepoint(word_size,
1597 context,
1598 expect_null_mutator_alloc_region);
1599 if (result != NULL) {
1600 assert(*gc_succeeded, "sanity");
1601 return result;
1602 }
1603
1604 // In a G1 heap, we're supposed to keep allocation from failing by
1605 // incremental pauses. Therefore, at least for now, we'll favor
1606 // expansion over collection. (This might change in the future if we can
1607 // do something smarter than full collection to satisfy a failed alloc.)
1608 result = expand_and_allocate(word_size, context);
1609 if (result != NULL) {
1610 assert(*gc_succeeded, "sanity");
1611 return result;
1612 }
1613
1614 if (do_gc) {
1615 // Expansion didn't work, we'll try to do a Full GC.
1616 *gc_succeeded = do_collection(false, /* explicit_gc */
1617 clear_all_soft_refs,
1618 word_size);
1619 }
1620
1621 return NULL;
1622 }
1623
1624 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1625 AllocationContext_t context,
1626 bool* succeeded) {
1627 assert_at_safepoint(true /* should_be_vm_thread */);
1628
1629 // Attempts to allocate followed by Full GC.
1630 HeapWord* result =
1631 satisfy_failed_allocation_helper(word_size,
1632 context,
1633 true, /* do_gc */
1634 false, /* clear_all_soft_refs */
1635 false, /* expect_null_mutator_alloc_region */
1636 succeeded);
1637
1638 if (result != NULL || !*succeeded) {
1639 return result;
1640 }
1641
1642 // Attempts to allocate followed by Full GC that will collect all soft references.
1643 result = satisfy_failed_allocation_helper(word_size,
1644 context,
1645 true, /* do_gc */
1646 true, /* clear_all_soft_refs */
1647 true, /* expect_null_mutator_alloc_region */
1648 succeeded);
1649
1650 if (result != NULL || !*succeeded) {
1651 return result;
1652 }
1653
1654 // Attempts to allocate, no GC
1655 result = satisfy_failed_allocation_helper(word_size,
1656 context,
1657 false, /* do_gc */
1658 false, /* clear_all_soft_refs */
1659 true, /* expect_null_mutator_alloc_region */
1660 succeeded);
1661
1662 if (result != NULL) {
1663 assert(*succeeded, "sanity");
1664 return result;
1665 }
1666
1667 assert(!collector_policy()->should_clear_all_soft_refs(),
1668 "Flag should have been handled and cleared prior to this point");
1669
1670 // What else? We might try synchronous finalization later. If the total
1671 // space available is large enough for the allocation, then a more
1672 // complete compaction phase than we've tried so far might be
1673 // appropriate.
1674 assert(*succeeded, "sanity");
1675 return NULL;
1676 }
1677
1678 // Attempting to expand the heap sufficiently
1679 // to support an allocation of the given "word_size". If
1680 // successful, perform the allocation and return the address of the
1681 // allocated block, or else "NULL".
1682
1683 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1684 assert_at_safepoint(true /* should_be_vm_thread */);
1685
1686 verify_region_sets_optional();
1687
1688 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1689 ergo_verbose1(ErgoHeapSizing,
1690 "attempt heap expansion",
1691 ergo_format_reason("allocation request failed")
1692 ergo_format_byte("allocation request"),
1693 word_size * HeapWordSize);
1694 if (expand(expand_bytes)) {
1695 _hrm.verify_optional();
1696 verify_region_sets_optional();
1697 return attempt_allocation_at_safepoint(word_size,
1698 context,
1699 false /* expect_null_mutator_alloc_region */);
1700 }
1701 return NULL;
1702 }
1703
1704 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1705 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1706 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1707 HeapRegion::GrainBytes);
1708 ergo_verbose2(ErgoHeapSizing,
1709 "expand the heap",
1710 ergo_format_byte("requested expansion amount")
1711 ergo_format_byte("attempted expansion amount"),
1712 expand_bytes, aligned_expand_bytes);
1713
1714 if (is_maximal_no_gc()) {
1715 ergo_verbose0(ErgoHeapSizing,
1716 "did not expand the heap",
1717 ergo_format_reason("heap already fully expanded"));
1718 return false;
1719 }
1720
1721 double expand_heap_start_time_sec = os::elapsedTime();
1722 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1723 assert(regions_to_expand > 0, "Must expand by at least one region");
1724
1725 uint expanded_by = _hrm.expand_by(regions_to_expand);
1726 if (expand_time_ms != NULL) {
1727 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1728 }
1729
1730 if (expanded_by > 0) {
1731 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1732 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1733 g1_policy()->record_new_heap_size(num_regions());
1734 } else {
1735 ergo_verbose0(ErgoHeapSizing,
1736 "did not expand the heap",
1737 ergo_format_reason("heap expansion operation failed"));
1738 // The expansion of the virtual storage space was unsuccessful.
1739 // Let's see if it was because we ran out of swap.
1740 if (G1ExitOnExpansionFailure &&
1741 _hrm.available() >= regions_to_expand) {
1742 // We had head room...
1743 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1744 }
1745 }
1746 return regions_to_expand > 0;
1747 }
1748
1749 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1750 size_t aligned_shrink_bytes =
1751 ReservedSpace::page_align_size_down(shrink_bytes);
1752 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1753 HeapRegion::GrainBytes);
1754 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1755
1756 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1757 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1758
1759 ergo_verbose3(ErgoHeapSizing,
1760 "shrink the heap",
1761 ergo_format_byte("requested shrinking amount")
1762 ergo_format_byte("aligned shrinking amount")
1763 ergo_format_byte("attempted shrinking amount"),
1764 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1765 if (num_regions_removed > 0) {
1766 g1_policy()->record_new_heap_size(num_regions());
1767 } else {
1768 ergo_verbose0(ErgoHeapSizing,
1769 "did not shrink the heap",
1770 ergo_format_reason("heap shrinking operation failed"));
1771 }
1772 }
1773
1774 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1775 verify_region_sets_optional();
1776
1777 // We should only reach here at the end of a Full GC which means we
1778 // should not not be holding to any GC alloc regions. The method
1779 // below will make sure of that and do any remaining clean up.
1780 _allocator->abandon_gc_alloc_regions();
1781
1782 // Instead of tearing down / rebuilding the free lists here, we
1783 // could instead use the remove_all_pending() method on free_list to
1784 // remove only the ones that we need to remove.
1785 tear_down_region_sets(true /* free_list_only */);
1786 shrink_helper(shrink_bytes);
1787 rebuild_region_sets(true /* free_list_only */);
1788
1789 _hrm.verify_optional();
1790 verify_region_sets_optional();
1791 }
1792
1793 // Public methods.
1794
1795 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1796 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1797 #endif // _MSC_VER
1798
1799
1800 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1801 CollectedHeap(),
1802 _g1_policy(policy_),
1803 _dirty_card_queue_set(false),
1804 _into_cset_dirty_card_queue_set(false),
1805 _is_alive_closure_cm(this),
1806 _is_alive_closure_stw(this),
1807 _ref_processor_cm(NULL),
1808 _ref_processor_stw(NULL),
1809 _bot_shared(NULL),
1810 _cg1r(NULL),
1811 _g1mm(NULL),
1812 _refine_cte_cl(NULL),
1813 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1814 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1815 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1816 _humongous_reclaim_candidates(),
1817 _has_humongous_reclaim_candidates(false),
1818 _archive_allocator(NULL),
1819 _free_regions_coming(false),
1820 _young_list(new YoungList(this)),
1821 _gc_time_stamp(0),
1822 _summary_bytes_used(0),
1823 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1824 _old_evac_stats(OldPLABSize, PLABWeight),
1825 _expand_heap_after_alloc_failure(true),
1826 _old_marking_cycles_started(0),
1827 _old_marking_cycles_completed(0),
1828 _heap_summary_sent(false),
1829 _in_cset_fast_test(),
1830 _dirty_cards_region_list(NULL),
1831 _worker_cset_start_region(NULL),
1832 _worker_cset_start_region_time_stamp(NULL),
1833 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1834 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1835 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1836 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1837
1838 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1839 /* are_GC_task_threads */true,
1840 /* are_ConcurrentGC_threads */false);
1841 _workers->initialize_workers();
1842
1843 _allocator = G1Allocator::create_allocator(this);
1844 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1845
1846 // Override the default _filler_array_max_size so that no humongous filler
1847 // objects are created.
1848 _filler_array_max_size = _humongous_object_threshold_in_words;
1849
1850 uint n_queues = ParallelGCThreads;
1851 _task_queues = new RefToScanQueueSet(n_queues);
1852
1853 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1854 assert(n_rem_sets > 0, "Invariant.");
1855
1856 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1857 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1858 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1859
1860 for (uint i = 0; i < n_queues; i++) {
1861 RefToScanQueue* q = new RefToScanQueue();
1862 q->initialize();
1863 _task_queues->register_queue(i, q);
1864 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1865 }
1866 clear_cset_start_regions();
1867
1868 // Initialize the G1EvacuationFailureALot counters and flags.
1869 NOT_PRODUCT(reset_evacuation_should_fail();)
1870
1871 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1872 }
1873
1874 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1875 size_t size,
1876 size_t translation_factor) {
1877 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1878 // Allocate a new reserved space, preferring to use large pages.
1879 ReservedSpace rs(size, preferred_page_size);
1880 G1RegionToSpaceMapper* result =
1881 G1RegionToSpaceMapper::create_mapper(rs,
1882 size,
1883 rs.alignment(),
1884 HeapRegion::GrainBytes,
1885 translation_factor,
1886 mtGC);
1887 if (TracePageSizes) {
1888 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1889 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1890 }
1891 return result;
1892 }
1893
1894 jint G1CollectedHeap::initialize() {
1895 CollectedHeap::pre_initialize();
1896 os::enable_vtime();
1897
1898 G1Log::init();
1899
1900 // Necessary to satisfy locking discipline assertions.
1901
1902 MutexLocker x(Heap_lock);
1903
1904 // We have to initialize the printer before committing the heap, as
1905 // it will be used then.
1906 _hr_printer.set_active(G1PrintHeapRegions);
1907
1908 // While there are no constraints in the GC code that HeapWordSize
1909 // be any particular value, there are multiple other areas in the
1910 // system which believe this to be true (e.g. oop->object_size in some
1911 // cases incorrectly returns the size in wordSize units rather than
1912 // HeapWordSize).
1913 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1914
1915 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1916 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1917 size_t heap_alignment = collector_policy()->heap_alignment();
1918
1919 // Ensure that the sizes are properly aligned.
1920 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1921 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1922 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1923
1924 _refine_cte_cl = new RefineCardTableEntryClosure();
1925
1926 jint ecode = JNI_OK;
1927 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1928 if (_cg1r == NULL) {
1929 return ecode;
1930 }
1931
1932 // Reserve the maximum.
1933
1934 // When compressed oops are enabled, the preferred heap base
1935 // is calculated by subtracting the requested size from the
1936 // 32Gb boundary and using the result as the base address for
1937 // heap reservation. If the requested size is not aligned to
1938 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1939 // into the ReservedHeapSpace constructor) then the actual
1940 // base of the reserved heap may end up differing from the
1941 // address that was requested (i.e. the preferred heap base).
1942 // If this happens then we could end up using a non-optimal
1943 // compressed oops mode.
1944
1945 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1946 heap_alignment);
1947
1948 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1949
1950 // Create the barrier set for the entire reserved region.
1951 G1SATBCardTableLoggingModRefBS* bs
1952 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1953 bs->initialize();
1954 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1955 set_barrier_set(bs);
1956
1957 // Also create a G1 rem set.
1958 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1959
1960 // Carve out the G1 part of the heap.
1961
1962 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1963 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1964 G1RegionToSpaceMapper* heap_storage =
1965 G1RegionToSpaceMapper::create_mapper(g1_rs,
1966 g1_rs.size(),
1967 page_size,
1968 HeapRegion::GrainBytes,
1969 1,
1970 mtJavaHeap);
1971 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1972 max_byte_size, page_size,
1973 heap_rs.base(),
1974 heap_rs.size());
1975 heap_storage->set_mapping_changed_listener(&_listener);
1976
1977 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1978 G1RegionToSpaceMapper* bot_storage =
1979 create_aux_memory_mapper("Block offset table",
1980 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1981 G1BlockOffsetSharedArray::heap_map_factor());
1982
1983 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1984 G1RegionToSpaceMapper* cardtable_storage =
1985 create_aux_memory_mapper("Card table",
1986 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1987 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1988
1989 G1RegionToSpaceMapper* card_counts_storage =
1990 create_aux_memory_mapper("Card counts table",
1991 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1992 G1CardCounts::heap_map_factor());
1993
1994 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1995 G1RegionToSpaceMapper* prev_bitmap_storage =
1996 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1997 G1RegionToSpaceMapper* next_bitmap_storage =
1998 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1999
2000 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2001 g1_barrier_set()->initialize(cardtable_storage);
2002 // Do later initialization work for concurrent refinement.
2003 _cg1r->init(card_counts_storage);
2004
2005 // 6843694 - ensure that the maximum region index can fit
2006 // in the remembered set structures.
2007 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2008 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2009
2010 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2011 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2012 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2013 "too many cards per region");
2014
2015 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2016
2017 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2018
2019 {
2020 HeapWord* start = _hrm.reserved().start();
2021 HeapWord* end = _hrm.reserved().end();
2022 size_t granularity = HeapRegion::GrainBytes;
2023
2024 _in_cset_fast_test.initialize(start, end, granularity);
2025 _humongous_reclaim_candidates.initialize(start, end, granularity);
2026 }
2027
2028 // Create the ConcurrentMark data structure and thread.
2029 // (Must do this late, so that "max_regions" is defined.)
2030 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2031 if (_cm == NULL || !_cm->completed_initialization()) {
2032 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2033 return JNI_ENOMEM;
2034 }
2035 _cmThread = _cm->cmThread();
2036
2037 // Initialize the from_card cache structure of HeapRegionRemSet.
2038 HeapRegionRemSet::init_heap(max_regions());
2039
2040 // Now expand into the initial heap size.
2041 if (!expand(init_byte_size)) {
2042 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2043 return JNI_ENOMEM;
2044 }
2045
2046 // Perform any initialization actions delegated to the policy.
2047 g1_policy()->init();
2048
2049 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2050 SATB_Q_FL_lock,
2051 G1SATBProcessCompletedThreshold,
2052 Shared_SATB_Q_lock);
2053
2054 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2055 DirtyCardQ_CBL_mon,
2056 DirtyCardQ_FL_lock,
2057 concurrent_g1_refine()->yellow_zone(),
2058 concurrent_g1_refine()->red_zone(),
2059 Shared_DirtyCardQ_lock);
2060
2061 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2062 DirtyCardQ_CBL_mon,
2063 DirtyCardQ_FL_lock,
2064 -1, // never trigger processing
2065 -1, // no limit on length
2066 Shared_DirtyCardQ_lock,
2067 &JavaThread::dirty_card_queue_set());
2068
2069 // Initialize the card queue set used to hold cards containing
2070 // references into the collection set.
2071 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2072 DirtyCardQ_CBL_mon,
2073 DirtyCardQ_FL_lock,
2074 -1, // never trigger processing
2075 -1, // no limit on length
2076 Shared_DirtyCardQ_lock,
2077 &JavaThread::dirty_card_queue_set());
2078
2079 // Here we allocate the dummy HeapRegion that is required by the
2080 // G1AllocRegion class.
2081 HeapRegion* dummy_region = _hrm.get_dummy_region();
2082
2083 // We'll re-use the same region whether the alloc region will
2084 // require BOT updates or not and, if it doesn't, then a non-young
2085 // region will complain that it cannot support allocations without
2086 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2087 dummy_region->set_eden();
2088 // Make sure it's full.
2089 dummy_region->set_top(dummy_region->end());
2090 G1AllocRegion::setup(this, dummy_region);
2091
2092 _allocator->init_mutator_alloc_region();
2093
2094 // Do create of the monitoring and management support so that
2095 // values in the heap have been properly initialized.
2096 _g1mm = new G1MonitoringSupport(this);
2097
2098 G1StringDedup::initialize();
2099
2100 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2101 for (uint i = 0; i < ParallelGCThreads; i++) {
2102 new (&_preserved_objs[i]) OopAndMarkOopStack();
2103 }
2104
2105 return JNI_OK;
2106 }
2107
2108 void G1CollectedHeap::stop() {
2109 // Stop all concurrent threads. We do this to make sure these threads
2110 // do not continue to execute and access resources (e.g. gclog_or_tty)
2111 // that are destroyed during shutdown.
2112 _cg1r->stop();
2113 _cmThread->stop();
2114 if (G1StringDedup::is_enabled()) {
2115 G1StringDedup::stop();
2116 }
2117 }
2118
2119 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2120 return HeapRegion::max_region_size();
2121 }
2122
2123 void G1CollectedHeap::post_initialize() {
2124 CollectedHeap::post_initialize();
2125 ref_processing_init();
2126 }
2127
2128 void G1CollectedHeap::ref_processing_init() {
2129 // Reference processing in G1 currently works as follows:
2130 //
2131 // * There are two reference processor instances. One is
2132 // used to record and process discovered references
2133 // during concurrent marking; the other is used to
2134 // record and process references during STW pauses
2135 // (both full and incremental).
2136 // * Both ref processors need to 'span' the entire heap as
2137 // the regions in the collection set may be dotted around.
2138 //
2139 // * For the concurrent marking ref processor:
2140 // * Reference discovery is enabled at initial marking.
2141 // * Reference discovery is disabled and the discovered
2142 // references processed etc during remarking.
2143 // * Reference discovery is MT (see below).
2144 // * Reference discovery requires a barrier (see below).
2145 // * Reference processing may or may not be MT
2146 // (depending on the value of ParallelRefProcEnabled
2147 // and ParallelGCThreads).
2148 // * A full GC disables reference discovery by the CM
2149 // ref processor and abandons any entries on it's
2150 // discovered lists.
2151 //
2152 // * For the STW processor:
2153 // * Non MT discovery is enabled at the start of a full GC.
2154 // * Processing and enqueueing during a full GC is non-MT.
2155 // * During a full GC, references are processed after marking.
2156 //
2157 // * Discovery (may or may not be MT) is enabled at the start
2158 // of an incremental evacuation pause.
2159 // * References are processed near the end of a STW evacuation pause.
2160 // * For both types of GC:
2161 // * Discovery is atomic - i.e. not concurrent.
2162 // * Reference discovery will not need a barrier.
2163
2164 MemRegion mr = reserved_region();
2165
2166 // Concurrent Mark ref processor
2167 _ref_processor_cm =
2168 new ReferenceProcessor(mr, // span
2169 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2170 // mt processing
2171 ParallelGCThreads,
2172 // degree of mt processing
2173 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2174 // mt discovery
2175 MAX2(ParallelGCThreads, ConcGCThreads),
2176 // degree of mt discovery
2177 false,
2178 // Reference discovery is not atomic
2179 &_is_alive_closure_cm);
2180 // is alive closure
2181 // (for efficiency/performance)
2182
2183 // STW ref processor
2184 _ref_processor_stw =
2185 new ReferenceProcessor(mr, // span
2186 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2187 // mt processing
2188 ParallelGCThreads,
2189 // degree of mt processing
2190 (ParallelGCThreads > 1),
2191 // mt discovery
2192 ParallelGCThreads,
2193 // degree of mt discovery
2194 true,
2195 // Reference discovery is atomic
2196 &_is_alive_closure_stw);
2197 // is alive closure
2198 // (for efficiency/performance)
2199 }
2200
2201 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2202 return g1_policy();
2203 }
2204
2205 size_t G1CollectedHeap::capacity() const {
2206 return _hrm.length() * HeapRegion::GrainBytes;
2207 }
2208
2209 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2210 hr->reset_gc_time_stamp();
2211 }
2212
2213 #ifndef PRODUCT
2214
2215 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2216 private:
2217 unsigned _gc_time_stamp;
2218 bool _failures;
2219
2220 public:
2221 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2222 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2223
2224 virtual bool doHeapRegion(HeapRegion* hr) {
2225 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2226 if (_gc_time_stamp != region_gc_time_stamp) {
2227 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2228 "expected %d", HR_FORMAT_PARAMS(hr),
2229 region_gc_time_stamp, _gc_time_stamp);
2230 _failures = true;
2231 }
2232 return false;
2233 }
2234
2235 bool failures() { return _failures; }
2236 };
2237
2238 void G1CollectedHeap::check_gc_time_stamps() {
2239 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2240 heap_region_iterate(&cl);
2241 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2242 }
2243 #endif // PRODUCT
2244
2245 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2246 _cg1r->hot_card_cache()->drain(cl, worker_i);
2247 }
2248
2249 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2250 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2251 size_t n_completed_buffers = 0;
2252 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2253 n_completed_buffers++;
2254 }
2255 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2256 dcqs.clear_n_completed_buffers();
2257 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2258 }
2259
2260 // Computes the sum of the storage used by the various regions.
2261 size_t G1CollectedHeap::used() const {
2262 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2263 if (_archive_allocator != NULL) {
2264 result += _archive_allocator->used();
2265 }
2266 return result;
2267 }
2268
2269 size_t G1CollectedHeap::used_unlocked() const {
2270 return _summary_bytes_used;
2271 }
2272
2273 class SumUsedClosure: public HeapRegionClosure {
2274 size_t _used;
2275 public:
2276 SumUsedClosure() : _used(0) {}
2277 bool doHeapRegion(HeapRegion* r) {
2278 _used += r->used();
2279 return false;
2280 }
2281 size_t result() { return _used; }
2282 };
2283
2284 size_t G1CollectedHeap::recalculate_used() const {
2285 double recalculate_used_start = os::elapsedTime();
2286
2287 SumUsedClosure blk;
2288 heap_region_iterate(&blk);
2289
2290 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2291 return blk.result();
2292 }
2293
2294 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2295 switch (cause) {
2296 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2297 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2298 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2299 case GCCause::_g1_humongous_allocation: return true;
2300 case GCCause::_update_allocation_context_stats_inc: return true;
2301 case GCCause::_wb_conc_mark: return true;
2302 default: return false;
2303 }
2304 }
2305
2306 #ifndef PRODUCT
2307 void G1CollectedHeap::allocate_dummy_regions() {
2308 // Let's fill up most of the region
2309 size_t word_size = HeapRegion::GrainWords - 1024;
2310 // And as a result the region we'll allocate will be humongous.
2311 guarantee(is_humongous(word_size), "sanity");
2312
2313 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2314 // Let's use the existing mechanism for the allocation
2315 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2316 AllocationContext::system());
2317 if (dummy_obj != NULL) {
2318 MemRegion mr(dummy_obj, word_size);
2319 CollectedHeap::fill_with_object(mr);
2320 } else {
2321 // If we can't allocate once, we probably cannot allocate
2322 // again. Let's get out of the loop.
2323 break;
2324 }
2325 }
2326 }
2327 #endif // !PRODUCT
2328
2329 void G1CollectedHeap::increment_old_marking_cycles_started() {
2330 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2331 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2332 "Wrong marking cycle count (started: %d, completed: %d)",
2333 _old_marking_cycles_started, _old_marking_cycles_completed);
2334
2335 _old_marking_cycles_started++;
2336 }
2337
2338 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2339 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2340
2341 // We assume that if concurrent == true, then the caller is a
2342 // concurrent thread that was joined the Suspendible Thread
2343 // Set. If there's ever a cheap way to check this, we should add an
2344 // assert here.
2345
2346 // Given that this method is called at the end of a Full GC or of a
2347 // concurrent cycle, and those can be nested (i.e., a Full GC can
2348 // interrupt a concurrent cycle), the number of full collections
2349 // completed should be either one (in the case where there was no
2350 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2351 // behind the number of full collections started.
2352
2353 // This is the case for the inner caller, i.e. a Full GC.
2354 assert(concurrent ||
2355 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2356 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2357 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2358 "is inconsistent with _old_marking_cycles_completed = %u",
2359 _old_marking_cycles_started, _old_marking_cycles_completed);
2360
2361 // This is the case for the outer caller, i.e. the concurrent cycle.
2362 assert(!concurrent ||
2363 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2364 "for outer caller (concurrent cycle): "
2365 "_old_marking_cycles_started = %u "
2366 "is inconsistent with _old_marking_cycles_completed = %u",
2367 _old_marking_cycles_started, _old_marking_cycles_completed);
2368
2369 _old_marking_cycles_completed += 1;
2370
2371 // We need to clear the "in_progress" flag in the CM thread before
2372 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2373 // is set) so that if a waiter requests another System.gc() it doesn't
2374 // incorrectly see that a marking cycle is still in progress.
2375 if (concurrent) {
2376 _cmThread->set_idle();
2377 }
2378
2379 // This notify_all() will ensure that a thread that called
2380 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2381 // and it's waiting for a full GC to finish will be woken up. It is
2382 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2383 FullGCCount_lock->notify_all();
2384 }
2385
2386 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2387 GCIdMarkAndRestore conc_gc_id_mark;
2388 collector_state()->set_concurrent_cycle_started(true);
2389 _gc_timer_cm->register_gc_start(start_time);
2390
2391 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2392 trace_heap_before_gc(_gc_tracer_cm);
2393 _cmThread->set_gc_id(GCId::current());
2394 }
2395
2396 void G1CollectedHeap::register_concurrent_cycle_end() {
2397 if (collector_state()->concurrent_cycle_started()) {
2398 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2399 if (_cm->has_aborted()) {
2400 _gc_tracer_cm->report_concurrent_mode_failure();
2401 }
2402
2403 _gc_timer_cm->register_gc_end();
2404 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2405
2406 // Clear state variables to prepare for the next concurrent cycle.
2407 collector_state()->set_concurrent_cycle_started(false);
2408 _heap_summary_sent = false;
2409 }
2410 }
2411
2412 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2413 if (collector_state()->concurrent_cycle_started()) {
2414 // This function can be called when:
2415 // the cleanup pause is run
2416 // the concurrent cycle is aborted before the cleanup pause.
2417 // the concurrent cycle is aborted after the cleanup pause,
2418 // but before the concurrent cycle end has been registered.
2419 // Make sure that we only send the heap information once.
2420 if (!_heap_summary_sent) {
2421 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2422 trace_heap_after_gc(_gc_tracer_cm);
2423 _heap_summary_sent = true;
2424 }
2425 }
2426 }
2427
2428 void G1CollectedHeap::collect(GCCause::Cause cause) {
2429 assert_heap_not_locked();
2430
2431 uint gc_count_before;
2432 uint old_marking_count_before;
2433 uint full_gc_count_before;
2434 bool retry_gc;
2435
2436 do {
2437 retry_gc = false;
2438
2439 {
2440 MutexLocker ml(Heap_lock);
2441
2442 // Read the GC count while holding the Heap_lock
2443 gc_count_before = total_collections();
2444 full_gc_count_before = total_full_collections();
2445 old_marking_count_before = _old_marking_cycles_started;
2446 }
2447
2448 if (should_do_concurrent_full_gc(cause)) {
2449 // Schedule an initial-mark evacuation pause that will start a
2450 // concurrent cycle. We're setting word_size to 0 which means that
2451 // we are not requesting a post-GC allocation.
2452 VM_G1IncCollectionPause op(gc_count_before,
2453 0, /* word_size */
2454 true, /* should_initiate_conc_mark */
2455 g1_policy()->max_pause_time_ms(),
2456 cause);
2457 op.set_allocation_context(AllocationContext::current());
2458
2459 VMThread::execute(&op);
2460 if (!op.pause_succeeded()) {
2461 if (old_marking_count_before == _old_marking_cycles_started) {
2462 retry_gc = op.should_retry_gc();
2463 } else {
2464 // A Full GC happened while we were trying to schedule the
2465 // initial-mark GC. No point in starting a new cycle given
2466 // that the whole heap was collected anyway.
2467 }
2468
2469 if (retry_gc) {
2470 if (GC_locker::is_active_and_needs_gc()) {
2471 GC_locker::stall_until_clear();
2472 }
2473 }
2474 }
2475 } else {
2476 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2477 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2478
2479 // Schedule a standard evacuation pause. We're setting word_size
2480 // to 0 which means that we are not requesting a post-GC allocation.
2481 VM_G1IncCollectionPause op(gc_count_before,
2482 0, /* word_size */
2483 false, /* should_initiate_conc_mark */
2484 g1_policy()->max_pause_time_ms(),
2485 cause);
2486 VMThread::execute(&op);
2487 } else {
2488 // Schedule a Full GC.
2489 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2490 VMThread::execute(&op);
2491 }
2492 }
2493 } while (retry_gc);
2494 }
2495
2496 bool G1CollectedHeap::is_in(const void* p) const {
2497 if (_hrm.reserved().contains(p)) {
2498 // Given that we know that p is in the reserved space,
2499 // heap_region_containing() should successfully
2500 // return the containing region.
2501 HeapRegion* hr = heap_region_containing(p);
2502 return hr->is_in(p);
2503 } else {
2504 return false;
2505 }
2506 }
2507
2508 #ifdef ASSERT
2509 bool G1CollectedHeap::is_in_exact(const void* p) const {
2510 bool contains = reserved_region().contains(p);
2511 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2512 if (contains && available) {
2513 return true;
2514 } else {
2515 return false;
2516 }
2517 }
2518 #endif
2519
2520 bool G1CollectedHeap::obj_in_cs(oop obj) {
2521 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2522 return r != NULL && r->in_collection_set();
2523 }
2524
2525 // Iteration functions.
2526
2527 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2528
2529 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2530 ExtendedOopClosure* _cl;
2531 public:
2532 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2533 bool doHeapRegion(HeapRegion* r) {
2534 if (!r->is_continues_humongous()) {
2535 r->oop_iterate(_cl);
2536 }
2537 return false;
2538 }
2539 };
2540
2541 // Iterates an ObjectClosure over all objects within a HeapRegion.
2542
2543 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2544 ObjectClosure* _cl;
2545 public:
2546 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2547 bool doHeapRegion(HeapRegion* r) {
2548 if (!r->is_continues_humongous()) {
2549 r->object_iterate(_cl);
2550 }
2551 return false;
2552 }
2553 };
2554
2555 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2556 IterateObjectClosureRegionClosure blk(cl);
2557 heap_region_iterate(&blk);
2558 }
2559
2560 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2561 _hrm.iterate(cl);
2562 }
2563
2564 void
2565 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2566 uint worker_id,
2567 HeapRegionClaimer *hrclaimer,
2568 bool concurrent) const {
2569 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2570 }
2571
2572 // Clear the cached CSet starting regions and (more importantly)
2573 // the time stamps. Called when we reset the GC time stamp.
2574 void G1CollectedHeap::clear_cset_start_regions() {
2575 assert(_worker_cset_start_region != NULL, "sanity");
2576 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2577
2578 for (uint i = 0; i < ParallelGCThreads; i++) {
2579 _worker_cset_start_region[i] = NULL;
2580 _worker_cset_start_region_time_stamp[i] = 0;
2581 }
2582 }
2583
2584 // Given the id of a worker, obtain or calculate a suitable
2585 // starting region for iterating over the current collection set.
2586 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2587 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2588
2589 HeapRegion* result = NULL;
2590 unsigned gc_time_stamp = get_gc_time_stamp();
2591
2592 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2593 // Cached starting region for current worker was set
2594 // during the current pause - so it's valid.
2595 // Note: the cached starting heap region may be NULL
2596 // (when the collection set is empty).
2597 result = _worker_cset_start_region[worker_i];
2598 assert(result == NULL || result->in_collection_set(), "sanity");
2599 return result;
2600 }
2601
2602 // The cached entry was not valid so let's calculate
2603 // a suitable starting heap region for this worker.
2604
2605 // We want the parallel threads to start their collection
2606 // set iteration at different collection set regions to
2607 // avoid contention.
2608 // If we have:
2609 // n collection set regions
2610 // p threads
2611 // Then thread t will start at region floor ((t * n) / p)
2612
2613 result = g1_policy()->collection_set();
2614 uint cs_size = g1_policy()->cset_region_length();
2615 uint active_workers = workers()->active_workers();
2616
2617 uint end_ind = (cs_size * worker_i) / active_workers;
2618 uint start_ind = 0;
2619
2620 if (worker_i > 0 &&
2621 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2622 // Previous workers starting region is valid
2623 // so let's iterate from there
2624 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2625 result = _worker_cset_start_region[worker_i - 1];
2626 }
2627
2628 for (uint i = start_ind; i < end_ind; i++) {
2629 result = result->next_in_collection_set();
2630 }
2631
2632 // Note: the calculated starting heap region may be NULL
2633 // (when the collection set is empty).
2634 assert(result == NULL || result->in_collection_set(), "sanity");
2635 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2636 "should be updated only once per pause");
2637 _worker_cset_start_region[worker_i] = result;
2638 OrderAccess::storestore();
2639 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2640 return result;
2641 }
2642
2643 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2644 HeapRegion* r = g1_policy()->collection_set();
2645 while (r != NULL) {
2646 HeapRegion* next = r->next_in_collection_set();
2647 if (cl->doHeapRegion(r)) {
2648 cl->incomplete();
2649 return;
2650 }
2651 r = next;
2652 }
2653 }
2654
2655 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2656 HeapRegionClosure *cl) {
2657 if (r == NULL) {
2658 // The CSet is empty so there's nothing to do.
2659 return;
2660 }
2661
2662 assert(r->in_collection_set(),
2663 "Start region must be a member of the collection set.");
2664 HeapRegion* cur = r;
2665 while (cur != NULL) {
2666 HeapRegion* next = cur->next_in_collection_set();
2667 if (cl->doHeapRegion(cur) && false) {
2668 cl->incomplete();
2669 return;
2670 }
2671 cur = next;
2672 }
2673 cur = g1_policy()->collection_set();
2674 while (cur != r) {
2675 HeapRegion* next = cur->next_in_collection_set();
2676 if (cl->doHeapRegion(cur) && false) {
2677 cl->incomplete();
2678 return;
2679 }
2680 cur = next;
2681 }
2682 }
2683
2684 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2685 HeapRegion* result = _hrm.next_region_in_heap(from);
2686 while (result != NULL && result->is_pinned()) {
2687 result = _hrm.next_region_in_heap(result);
2688 }
2689 return result;
2690 }
2691
2692 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2693 HeapRegion* hr = heap_region_containing(addr);
2694 return hr->block_start(addr);
2695 }
2696
2697 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2698 HeapRegion* hr = heap_region_containing(addr);
2699 return hr->block_size(addr);
2700 }
2701
2702 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2703 HeapRegion* hr = heap_region_containing(addr);
2704 return hr->block_is_obj(addr);
2705 }
2706
2707 bool G1CollectedHeap::supports_tlab_allocation() const {
2708 return true;
2709 }
2710
2711 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2712 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2713 }
2714
2715 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2716 return young_list()->eden_used_bytes();
2717 }
2718
2719 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2720 // must be equal to the humongous object limit.
2721 size_t G1CollectedHeap::max_tlab_size() const {
2722 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2723 }
2724
2725 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2726 AllocationContext_t context = AllocationContext::current();
2727 return _allocator->unsafe_max_tlab_alloc(context);
2728 }
2729
2730 size_t G1CollectedHeap::max_capacity() const {
2731 return _hrm.reserved().byte_size();
2732 }
2733
2734 jlong G1CollectedHeap::millis_since_last_gc() {
2735 // assert(false, "NYI");
2736 return 0;
2737 }
2738
2739 void G1CollectedHeap::prepare_for_verify() {
2740 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2741 ensure_parsability(false);
2742 }
2743 g1_rem_set()->prepare_for_verify();
2744 }
2745
2746 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2747 VerifyOption vo) {
2748 switch (vo) {
2749 case VerifyOption_G1UsePrevMarking:
2750 return hr->obj_allocated_since_prev_marking(obj);
2751 case VerifyOption_G1UseNextMarking:
2752 return hr->obj_allocated_since_next_marking(obj);
2753 case VerifyOption_G1UseMarkWord:
2754 return false;
2755 default:
2756 ShouldNotReachHere();
2757 }
2758 return false; // keep some compilers happy
2759 }
2760
2761 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2762 switch (vo) {
2763 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2764 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2765 case VerifyOption_G1UseMarkWord: return NULL;
2766 default: ShouldNotReachHere();
2767 }
2768 return NULL; // keep some compilers happy
2769 }
2770
2771 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2772 switch (vo) {
2773 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2774 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2775 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2776 default: ShouldNotReachHere();
2777 }
2778 return false; // keep some compilers happy
2779 }
2780
2781 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2782 switch (vo) {
2783 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2784 case VerifyOption_G1UseNextMarking: return "NTAMS";
2785 case VerifyOption_G1UseMarkWord: return "NONE";
2786 default: ShouldNotReachHere();
2787 }
2788 return NULL; // keep some compilers happy
2789 }
2790
2791 class VerifyRootsClosure: public OopClosure {
2792 private:
2793 G1CollectedHeap* _g1h;
2794 VerifyOption _vo;
2795 bool _failures;
2796 public:
2797 // _vo == UsePrevMarking -> use "prev" marking information,
2798 // _vo == UseNextMarking -> use "next" marking information,
2799 // _vo == UseMarkWord -> use mark word from object header.
2800 VerifyRootsClosure(VerifyOption vo) :
2801 _g1h(G1CollectedHeap::heap()),
2802 _vo(vo),
2803 _failures(false) { }
2804
2805 bool failures() { return _failures; }
2806
2807 template <class T> void do_oop_nv(T* p) {
2808 T heap_oop = oopDesc::load_heap_oop(p);
2809 if (!oopDesc::is_null(heap_oop)) {
2810 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2811 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2812 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2813 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2814 if (_vo == VerifyOption_G1UseMarkWord) {
2815 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2816 }
2817 obj->print_on(gclog_or_tty);
2818 _failures = true;
2819 }
2820 }
2821 }
2822
2823 void do_oop(oop* p) { do_oop_nv(p); }
2824 void do_oop(narrowOop* p) { do_oop_nv(p); }
2825 };
2826
2827 class G1VerifyCodeRootOopClosure: public OopClosure {
2828 G1CollectedHeap* _g1h;
2829 OopClosure* _root_cl;
2830 nmethod* _nm;
2831 VerifyOption _vo;
2832 bool _failures;
2833
2834 template <class T> void do_oop_work(T* p) {
2835 // First verify that this root is live
2836 _root_cl->do_oop(p);
2837
2838 if (!G1VerifyHeapRegionCodeRoots) {
2839 // We're not verifying the code roots attached to heap region.
2840 return;
2841 }
2842
2843 // Don't check the code roots during marking verification in a full GC
2844 if (_vo == VerifyOption_G1UseMarkWord) {
2845 return;
2846 }
2847
2848 // Now verify that the current nmethod (which contains p) is
2849 // in the code root list of the heap region containing the
2850 // object referenced by p.
2851
2852 T heap_oop = oopDesc::load_heap_oop(p);
2853 if (!oopDesc::is_null(heap_oop)) {
2854 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2855
2856 // Now fetch the region containing the object
2857 HeapRegion* hr = _g1h->heap_region_containing(obj);
2858 HeapRegionRemSet* hrrs = hr->rem_set();
2859 // Verify that the strong code root list for this region
2860 // contains the nmethod
2861 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2862 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2863 "from nmethod " PTR_FORMAT " not in strong "
2864 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2865 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2866 _failures = true;
2867 }
2868 }
2869 }
2870
2871 public:
2872 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2873 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2874
2875 void do_oop(oop* p) { do_oop_work(p); }
2876 void do_oop(narrowOop* p) { do_oop_work(p); }
2877
2878 void set_nmethod(nmethod* nm) { _nm = nm; }
2879 bool failures() { return _failures; }
2880 };
2881
2882 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2883 G1VerifyCodeRootOopClosure* _oop_cl;
2884
2885 public:
2886 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2887 _oop_cl(oop_cl) {}
2888
2889 void do_code_blob(CodeBlob* cb) {
2890 nmethod* nm = cb->as_nmethod_or_null();
2891 if (nm != NULL) {
2892 _oop_cl->set_nmethod(nm);
2893 nm->oops_do(_oop_cl);
2894 }
2895 }
2896 };
2897
2898 class YoungRefCounterClosure : public OopClosure {
2899 G1CollectedHeap* _g1h;
2900 int _count;
2901 public:
2902 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2903 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2904 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2905
2906 int count() { return _count; }
2907 void reset_count() { _count = 0; };
2908 };
2909
2910 class VerifyKlassClosure: public KlassClosure {
2911 YoungRefCounterClosure _young_ref_counter_closure;
2912 OopClosure *_oop_closure;
2913 public:
2914 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2915 void do_klass(Klass* k) {
2916 k->oops_do(_oop_closure);
2917
2918 _young_ref_counter_closure.reset_count();
2919 k->oops_do(&_young_ref_counter_closure);
2920 if (_young_ref_counter_closure.count() > 0) {
2921 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2922 }
2923 }
2924 };
2925
2926 class VerifyLivenessOopClosure: public OopClosure {
2927 G1CollectedHeap* _g1h;
2928 VerifyOption _vo;
2929 public:
2930 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2931 _g1h(g1h), _vo(vo)
2932 { }
2933 void do_oop(narrowOop *p) { do_oop_work(p); }
2934 void do_oop( oop *p) { do_oop_work(p); }
2935
2936 template <class T> void do_oop_work(T *p) {
2937 oop obj = oopDesc::load_decode_heap_oop(p);
2938 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2939 "Dead object referenced by a not dead object");
2940 }
2941 };
2942
2943 class VerifyObjsInRegionClosure: public ObjectClosure {
2944 private:
2945 G1CollectedHeap* _g1h;
2946 size_t _live_bytes;
2947 HeapRegion *_hr;
2948 VerifyOption _vo;
2949 public:
2950 // _vo == UsePrevMarking -> use "prev" marking information,
2951 // _vo == UseNextMarking -> use "next" marking information,
2952 // _vo == UseMarkWord -> use mark word from object header.
2953 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2954 : _live_bytes(0), _hr(hr), _vo(vo) {
2955 _g1h = G1CollectedHeap::heap();
2956 }
2957 void do_object(oop o) {
2958 VerifyLivenessOopClosure isLive(_g1h, _vo);
2959 assert(o != NULL, "Huh?");
2960 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2961 // If the object is alive according to the mark word,
2962 // then verify that the marking information agrees.
2963 // Note we can't verify the contra-positive of the
2964 // above: if the object is dead (according to the mark
2965 // word), it may not be marked, or may have been marked
2966 // but has since became dead, or may have been allocated
2967 // since the last marking.
2968 if (_vo == VerifyOption_G1UseMarkWord) {
2969 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2970 }
2971
2972 o->oop_iterate_no_header(&isLive);
2973 if (!_hr->obj_allocated_since_prev_marking(o)) {
2974 size_t obj_size = o->size(); // Make sure we don't overflow
2975 _live_bytes += (obj_size * HeapWordSize);
2976 }
2977 }
2978 }
2979 size_t live_bytes() { return _live_bytes; }
2980 };
2981
2982 class VerifyArchiveOopClosure: public OopClosure {
2983 public:
2984 VerifyArchiveOopClosure(HeapRegion *hr) { }
2985 void do_oop(narrowOop *p) { do_oop_work(p); }
2986 void do_oop( oop *p) { do_oop_work(p); }
2987
2988 template <class T> void do_oop_work(T *p) {
2989 oop obj = oopDesc::load_decode_heap_oop(p);
2990 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
2991 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
2992 p2i(p), p2i(obj));
2993 }
2994 };
2995
2996 class VerifyArchiveRegionClosure: public ObjectClosure {
2997 public:
2998 VerifyArchiveRegionClosure(HeapRegion *hr) { }
2999 // Verify that all object pointers are to archive regions.
3000 void do_object(oop o) {
3001 VerifyArchiveOopClosure checkOop(NULL);
3002 assert(o != NULL, "Should not be here for NULL oops");
3003 o->oop_iterate_no_header(&checkOop);
3004 }
3005 };
3006
3007 class VerifyRegionClosure: public HeapRegionClosure {
3008 private:
3009 bool _par;
3010 VerifyOption _vo;
3011 bool _failures;
3012 public:
3013 // _vo == UsePrevMarking -> use "prev" marking information,
3014 // _vo == UseNextMarking -> use "next" marking information,
3015 // _vo == UseMarkWord -> use mark word from object header.
3016 VerifyRegionClosure(bool par, VerifyOption vo)
3017 : _par(par),
3018 _vo(vo),
3019 _failures(false) {}
3020
3021 bool failures() {
3022 return _failures;
3023 }
3024
3025 bool doHeapRegion(HeapRegion* r) {
3026 // For archive regions, verify there are no heap pointers to
3027 // non-pinned regions. For all others, verify liveness info.
3028 if (r->is_archive()) {
3029 VerifyArchiveRegionClosure verify_oop_pointers(r);
3030 r->object_iterate(&verify_oop_pointers);
3031 return true;
3032 }
3033 if (!r->is_continues_humongous()) {
3034 bool failures = false;
3035 r->verify(_vo, &failures);
3036 if (failures) {
3037 _failures = true;
3038 } else if (!r->is_starts_humongous()) {
3039 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3040 r->object_iterate(¬_dead_yet_cl);
3041 if (_vo != VerifyOption_G1UseNextMarking) {
3042 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3043 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3044 "max_live_bytes " SIZE_FORMAT " "
3045 "< calculated " SIZE_FORMAT,
3046 p2i(r->bottom()), p2i(r->end()),
3047 r->max_live_bytes(),
3048 not_dead_yet_cl.live_bytes());
3049 _failures = true;
3050 }
3051 } else {
3052 // When vo == UseNextMarking we cannot currently do a sanity
3053 // check on the live bytes as the calculation has not been
3054 // finalized yet.
3055 }
3056 }
3057 }
3058 return false; // stop the region iteration if we hit a failure
3059 }
3060 };
3061
3062 // This is the task used for parallel verification of the heap regions
3063
3064 class G1ParVerifyTask: public AbstractGangTask {
3065 private:
3066 G1CollectedHeap* _g1h;
3067 VerifyOption _vo;
3068 bool _failures;
3069 HeapRegionClaimer _hrclaimer;
3070
3071 public:
3072 // _vo == UsePrevMarking -> use "prev" marking information,
3073 // _vo == UseNextMarking -> use "next" marking information,
3074 // _vo == UseMarkWord -> use mark word from object header.
3075 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3076 AbstractGangTask("Parallel verify task"),
3077 _g1h(g1h),
3078 _vo(vo),
3079 _failures(false),
3080 _hrclaimer(g1h->workers()->active_workers()) {}
3081
3082 bool failures() {
3083 return _failures;
3084 }
3085
3086 void work(uint worker_id) {
3087 HandleMark hm;
3088 VerifyRegionClosure blk(true, _vo);
3089 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3090 if (blk.failures()) {
3091 _failures = true;
3092 }
3093 }
3094 };
3095
3096 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3097 if (SafepointSynchronize::is_at_safepoint()) {
3098 assert(Thread::current()->is_VM_thread(),
3099 "Expected to be executed serially by the VM thread at this point");
3100
3101 if (!silent) { gclog_or_tty->print("Roots "); }
3102 VerifyRootsClosure rootsCl(vo);
3103 VerifyKlassClosure klassCl(this, &rootsCl);
3104 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3105
3106 // We apply the relevant closures to all the oops in the
3107 // system dictionary, class loader data graph, the string table
3108 // and the nmethods in the code cache.
3109 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3110 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3111
3112 {
3113 G1RootProcessor root_processor(this, 1);
3114 root_processor.process_all_roots(&rootsCl,
3115 &cldCl,
3116 &blobsCl);
3117 }
3118
3119 bool failures = rootsCl.failures() || codeRootsCl.failures();
3120
3121 if (vo != VerifyOption_G1UseMarkWord) {
3122 // If we're verifying during a full GC then the region sets
3123 // will have been torn down at the start of the GC. Therefore
3124 // verifying the region sets will fail. So we only verify
3125 // the region sets when not in a full GC.
3126 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3127 verify_region_sets();
3128 }
3129
3130 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3131 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3132
3133 G1ParVerifyTask task(this, vo);
3134 workers()->run_task(&task);
3135 if (task.failures()) {
3136 failures = true;
3137 }
3138
3139 } else {
3140 VerifyRegionClosure blk(false, vo);
3141 heap_region_iterate(&blk);
3142 if (blk.failures()) {
3143 failures = true;
3144 }
3145 }
3146
3147 if (G1StringDedup::is_enabled()) {
3148 if (!silent) gclog_or_tty->print("StrDedup ");
3149 G1StringDedup::verify();
3150 }
3151
3152 if (failures) {
3153 gclog_or_tty->print_cr("Heap:");
3154 // It helps to have the per-region information in the output to
3155 // help us track down what went wrong. This is why we call
3156 // print_extended_on() instead of print_on().
3157 print_extended_on(gclog_or_tty);
3158 gclog_or_tty->cr();
3159 gclog_or_tty->flush();
3160 }
3161 guarantee(!failures, "there should not have been any failures");
3162 } else {
3163 if (!silent) {
3164 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3165 if (G1StringDedup::is_enabled()) {
3166 gclog_or_tty->print(", StrDedup");
3167 }
3168 gclog_or_tty->print(") ");
3169 }
3170 }
3171 }
3172
3173 void G1CollectedHeap::verify(bool silent) {
3174 verify(silent, VerifyOption_G1UsePrevMarking);
3175 }
3176
3177 double G1CollectedHeap::verify(bool guard, const char* msg) {
3178 double verify_time_ms = 0.0;
3179
3180 if (guard && total_collections() >= VerifyGCStartAt) {
3181 double verify_start = os::elapsedTime();
3182 HandleMark hm; // Discard invalid handles created during verification
3183 prepare_for_verify();
3184 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3185 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3186 }
3187
3188 return verify_time_ms;
3189 }
3190
3191 void G1CollectedHeap::verify_before_gc() {
3192 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3193 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3194 }
3195
3196 void G1CollectedHeap::verify_after_gc() {
3197 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3198 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3199 }
3200
3201 class PrintRegionClosure: public HeapRegionClosure {
3202 outputStream* _st;
3203 public:
3204 PrintRegionClosure(outputStream* st) : _st(st) {}
3205 bool doHeapRegion(HeapRegion* r) {
3206 r->print_on(_st);
3207 return false;
3208 }
3209 };
3210
3211 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3212 const HeapRegion* hr,
3213 const VerifyOption vo) const {
3214 switch (vo) {
3215 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3216 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3217 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3218 default: ShouldNotReachHere();
3219 }
3220 return false; // keep some compilers happy
3221 }
3222
3223 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3224 const VerifyOption vo) const {
3225 switch (vo) {
3226 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3227 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3228 case VerifyOption_G1UseMarkWord: {
3229 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3230 return !obj->is_gc_marked() && !hr->is_archive();
3231 }
3232 default: ShouldNotReachHere();
3233 }
3234 return false; // keep some compilers happy
3235 }
3236
3237 void G1CollectedHeap::print_on(outputStream* st) const {
3238 st->print(" %-20s", "garbage-first heap");
3239 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3240 capacity()/K, used_unlocked()/K);
3241 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3242 p2i(_hrm.reserved().start()),
3243 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3244 p2i(_hrm.reserved().end()));
3245 st->cr();
3246 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3247 uint young_regions = _young_list->length();
3248 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3249 (size_t) young_regions * HeapRegion::GrainBytes / K);
3250 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3251 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3252 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3253 st->cr();
3254 MetaspaceAux::print_on(st);
3255 }
3256
3257 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3258 print_on(st);
3259
3260 // Print the per-region information.
3261 st->cr();
3262 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3263 "HS=humongous(starts), HC=humongous(continues), "
3264 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3265 "PTAMS=previous top-at-mark-start, "
3266 "NTAMS=next top-at-mark-start)");
3267 PrintRegionClosure blk(st);
3268 heap_region_iterate(&blk);
3269 }
3270
3271 void G1CollectedHeap::print_on_error(outputStream* st) const {
3272 this->CollectedHeap::print_on_error(st);
3273
3274 if (_cm != NULL) {
3275 st->cr();
3276 _cm->print_on_error(st);
3277 }
3278 }
3279
3280 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3281 workers()->print_worker_threads_on(st);
3282 _cmThread->print_on(st);
3283 st->cr();
3284 _cm->print_worker_threads_on(st);
3285 _cg1r->print_worker_threads_on(st);
3286 if (G1StringDedup::is_enabled()) {
3287 G1StringDedup::print_worker_threads_on(st);
3288 }
3289 }
3290
3291 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3292 workers()->threads_do(tc);
3293 tc->do_thread(_cmThread);
3294 _cg1r->threads_do(tc);
3295 if (G1StringDedup::is_enabled()) {
3296 G1StringDedup::threads_do(tc);
3297 }
3298 }
3299
3300 void G1CollectedHeap::print_tracing_info() const {
3301 // We'll overload this to mean "trace GC pause statistics."
3302 if (TraceYoungGenTime || TraceOldGenTime) {
3303 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3304 // to that.
3305 g1_policy()->print_tracing_info();
3306 }
3307 if (G1SummarizeRSetStats) {
3308 g1_rem_set()->print_summary_info();
3309 }
3310 if (G1SummarizeConcMark) {
3311 concurrent_mark()->print_summary_info();
3312 }
3313 g1_policy()->print_yg_surv_rate_info();
3314 }
3315
3316 #ifndef PRODUCT
3317 // Helpful for debugging RSet issues.
3318
3319 class PrintRSetsClosure : public HeapRegionClosure {
3320 private:
3321 const char* _msg;
3322 size_t _occupied_sum;
3323
3324 public:
3325 bool doHeapRegion(HeapRegion* r) {
3326 HeapRegionRemSet* hrrs = r->rem_set();
3327 size_t occupied = hrrs->occupied();
3328 _occupied_sum += occupied;
3329
3330 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3331 HR_FORMAT_PARAMS(r));
3332 if (occupied == 0) {
3333 gclog_or_tty->print_cr(" RSet is empty");
3334 } else {
3335 hrrs->print();
3336 }
3337 gclog_or_tty->print_cr("----------");
3338 return false;
3339 }
3340
3341 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3342 gclog_or_tty->cr();
3343 gclog_or_tty->print_cr("========================================");
3344 gclog_or_tty->print_cr("%s", msg);
3345 gclog_or_tty->cr();
3346 }
3347
3348 ~PrintRSetsClosure() {
3349 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3350 gclog_or_tty->print_cr("========================================");
3351 gclog_or_tty->cr();
3352 }
3353 };
3354
3355 void G1CollectedHeap::print_cset_rsets() {
3356 PrintRSetsClosure cl("Printing CSet RSets");
3357 collection_set_iterate(&cl);
3358 }
3359
3360 void G1CollectedHeap::print_all_rsets() {
3361 PrintRSetsClosure cl("Printing All RSets");;
3362 heap_region_iterate(&cl);
3363 }
3364 #endif // PRODUCT
3365
3366 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3367 YoungList* young_list = heap()->young_list();
3368
3369 size_t eden_used_bytes = young_list->eden_used_bytes();
3370 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3371
3372 size_t eden_capacity_bytes =
3373 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3374
3375 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3376 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3377 }
3378
3379 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3380 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3381 stats->unused(), stats->used(), stats->region_end_waste(),
3382 stats->regions_filled(), stats->direct_allocated(),
3383 stats->failure_used(), stats->failure_waste());
3384 }
3385
3386 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3387 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3388 gc_tracer->report_gc_heap_summary(when, heap_summary);
3389
3390 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3391 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3392 }
3393
3394
3395 G1CollectedHeap* G1CollectedHeap::heap() {
3396 CollectedHeap* heap = Universe::heap();
3397 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3398 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3399 return (G1CollectedHeap*)heap;
3400 }
3401
3402 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3403 // always_do_update_barrier = false;
3404 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3405 // Fill TLAB's and such
3406 accumulate_statistics_all_tlabs();
3407 ensure_parsability(true);
3408
3409 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3410 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3411 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3412 }
3413 }
3414
3415 void G1CollectedHeap::gc_epilogue(bool full) {
3416
3417 if (G1SummarizeRSetStats &&
3418 (G1SummarizeRSetStatsPeriod > 0) &&
3419 // we are at the end of the GC. Total collections has already been increased.
3420 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3421 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3422 }
3423
3424 // FIXME: what is this about?
3425 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3426 // is set.
3427 #if defined(COMPILER2) || INCLUDE_JVMCI
3428 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3429 #endif
3430 // always_do_update_barrier = true;
3431
3432 resize_all_tlabs();
3433 allocation_context_stats().update(full);
3434
3435 // We have just completed a GC. Update the soft reference
3436 // policy with the new heap occupancy
3437 Universe::update_heap_info_at_gc();
3438 }
3439
3440 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3441 uint gc_count_before,
3442 bool* succeeded,
3443 GCCause::Cause gc_cause) {
3444 assert_heap_not_locked_and_not_at_safepoint();
3445 g1_policy()->record_stop_world_start();
3446 VM_G1IncCollectionPause op(gc_count_before,
3447 word_size,
3448 false, /* should_initiate_conc_mark */
3449 g1_policy()->max_pause_time_ms(),
3450 gc_cause);
3451
3452 op.set_allocation_context(AllocationContext::current());
3453 VMThread::execute(&op);
3454
3455 HeapWord* result = op.result();
3456 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3457 assert(result == NULL || ret_succeeded,
3458 "the result should be NULL if the VM did not succeed");
3459 *succeeded = ret_succeeded;
3460
3461 assert_heap_not_locked();
3462 return result;
3463 }
3464
3465 void
3466 G1CollectedHeap::doConcurrentMark() {
3467 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3468 if (!_cmThread->in_progress()) {
3469 _cmThread->set_started();
3470 CGC_lock->notify();
3471 }
3472 }
3473
3474 size_t G1CollectedHeap::pending_card_num() {
3475 size_t extra_cards = 0;
3476 JavaThread *curr = Threads::first();
3477 while (curr != NULL) {
3478 DirtyCardQueue& dcq = curr->dirty_card_queue();
3479 extra_cards += dcq.size();
3480 curr = curr->next();
3481 }
3482 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3483 size_t buffer_size = dcqs.buffer_size();
3484 size_t buffer_num = dcqs.completed_buffers_num();
3485
3486 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3487 // in bytes - not the number of 'entries'. We need to convert
3488 // into a number of cards.
3489 return (buffer_size * buffer_num + extra_cards) / oopSize;
3490 }
3491
3492 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3493 private:
3494 size_t _total_humongous;
3495 size_t _candidate_humongous;
3496
3497 DirtyCardQueue _dcq;
3498
3499 // We don't nominate objects with many remembered set entries, on
3500 // the assumption that such objects are likely still live.
3501 bool is_remset_small(HeapRegion* region) const {
3502 HeapRegionRemSet* const rset = region->rem_set();
3503 return G1EagerReclaimHumongousObjectsWithStaleRefs
3504 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3505 : rset->is_empty();
3506 }
3507
3508 bool is_typeArray_region(HeapRegion* region) const {
3509 return oop(region->bottom())->is_typeArray();
3510 }
3511
3512 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3513 assert(region->is_starts_humongous(), "Must start a humongous object");
3514
3515 // Candidate selection must satisfy the following constraints
3516 // while concurrent marking is in progress:
3517 //
3518 // * In order to maintain SATB invariants, an object must not be
3519 // reclaimed if it was allocated before the start of marking and
3520 // has not had its references scanned. Such an object must have
3521 // its references (including type metadata) scanned to ensure no
3522 // live objects are missed by the marking process. Objects
3523 // allocated after the start of concurrent marking don't need to
3524 // be scanned.
3525 //
3526 // * An object must not be reclaimed if it is on the concurrent
3527 // mark stack. Objects allocated after the start of concurrent
3528 // marking are never pushed on the mark stack.
3529 //
3530 // Nominating only objects allocated after the start of concurrent
3531 // marking is sufficient to meet both constraints. This may miss
3532 // some objects that satisfy the constraints, but the marking data
3533 // structures don't support efficiently performing the needed
3534 // additional tests or scrubbing of the mark stack.
3535 //
3536 // However, we presently only nominate is_typeArray() objects.
3537 // A humongous object containing references induces remembered
3538 // set entries on other regions. In order to reclaim such an
3539 // object, those remembered sets would need to be cleaned up.
3540 //
3541 // We also treat is_typeArray() objects specially, allowing them
3542 // to be reclaimed even if allocated before the start of
3543 // concurrent mark. For this we rely on mark stack insertion to
3544 // exclude is_typeArray() objects, preventing reclaiming an object
3545 // that is in the mark stack. We also rely on the metadata for
3546 // such objects to be built-in and so ensured to be kept live.
3547 // Frequent allocation and drop of large binary blobs is an
3548 // important use case for eager reclaim, and this special handling
3549 // may reduce needed headroom.
3550
3551 return is_typeArray_region(region) && is_remset_small(region);
3552 }
3553
3554 public:
3555 RegisterHumongousWithInCSetFastTestClosure()
3556 : _total_humongous(0),
3557 _candidate_humongous(0),
3558 _dcq(&JavaThread::dirty_card_queue_set()) {
3559 }
3560
3561 virtual bool doHeapRegion(HeapRegion* r) {
3562 if (!r->is_starts_humongous()) {
3563 return false;
3564 }
3565 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3566
3567 bool is_candidate = humongous_region_is_candidate(g1h, r);
3568 uint rindex = r->hrm_index();
3569 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3570 if (is_candidate) {
3571 _candidate_humongous++;
3572 g1h->register_humongous_region_with_cset(rindex);
3573 // Is_candidate already filters out humongous object with large remembered sets.
3574 // If we have a humongous object with a few remembered sets, we simply flush these
3575 // remembered set entries into the DCQS. That will result in automatic
3576 // re-evaluation of their remembered set entries during the following evacuation
3577 // phase.
3578 if (!r->rem_set()->is_empty()) {
3579 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3580 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3581 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3582 HeapRegionRemSetIterator hrrs(r->rem_set());
3583 size_t card_index;
3584 while (hrrs.has_next(card_index)) {
3585 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3586 // The remembered set might contain references to already freed
3587 // regions. Filter out such entries to avoid failing card table
3588 // verification.
3589 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3590 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3591 *card_ptr = CardTableModRefBS::dirty_card_val();
3592 _dcq.enqueue(card_ptr);
3593 }
3594 }
3595 }
3596 r->rem_set()->clear_locked();
3597 }
3598 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3599 }
3600 _total_humongous++;
3601
3602 return false;
3603 }
3604
3605 size_t total_humongous() const { return _total_humongous; }
3606 size_t candidate_humongous() const { return _candidate_humongous; }
3607
3608 void flush_rem_set_entries() { _dcq.flush(); }
3609 };
3610
3611 void G1CollectedHeap::register_humongous_regions_with_cset() {
3612 if (!G1EagerReclaimHumongousObjects) {
3613 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3614 return;
3615 }
3616 double time = os::elapsed_counter();
3617
3618 // Collect reclaim candidate information and register candidates with cset.
3619 RegisterHumongousWithInCSetFastTestClosure cl;
3620 heap_region_iterate(&cl);
3621
3622 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3623 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3624 cl.total_humongous(),
3625 cl.candidate_humongous());
3626 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3627
3628 // Finally flush all remembered set entries to re-check into the global DCQS.
3629 cl.flush_rem_set_entries();
3630 }
3631
3632 #ifdef ASSERT
3633 class VerifyCSetClosure: public HeapRegionClosure {
3634 public:
3635 bool doHeapRegion(HeapRegion* hr) {
3636 // Here we check that the CSet region's RSet is ready for parallel
3637 // iteration. The fields that we'll verify are only manipulated
3638 // when the region is part of a CSet and is collected. Afterwards,
3639 // we reset these fields when we clear the region's RSet (when the
3640 // region is freed) so they are ready when the region is
3641 // re-allocated. The only exception to this is if there's an
3642 // evacuation failure and instead of freeing the region we leave
3643 // it in the heap. In that case, we reset these fields during
3644 // evacuation failure handling.
3645 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3646
3647 // Here's a good place to add any other checks we'd like to
3648 // perform on CSet regions.
3649 return false;
3650 }
3651 };
3652 #endif // ASSERT
3653
3654 uint G1CollectedHeap::num_task_queues() const {
3655 return _task_queues->size();
3656 }
3657
3658 #if TASKQUEUE_STATS
3659 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3660 st->print_raw_cr("GC Task Stats");
3661 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3662 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3663 }
3664
3665 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3666 print_taskqueue_stats_hdr(st);
3667
3668 TaskQueueStats totals;
3669 const uint n = num_task_queues();
3670 for (uint i = 0; i < n; ++i) {
3671 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3672 totals += task_queue(i)->stats;
3673 }
3674 st->print_raw("tot "); totals.print(st); st->cr();
3675
3676 DEBUG_ONLY(totals.verify());
3677 }
3678
3679 void G1CollectedHeap::reset_taskqueue_stats() {
3680 const uint n = num_task_queues();
3681 for (uint i = 0; i < n; ++i) {
3682 task_queue(i)->stats.reset();
3683 }
3684 }
3685 #endif // TASKQUEUE_STATS
3686
3687 void G1CollectedHeap::log_gc_header() {
3688 if (!G1Log::fine()) {
3689 return;
3690 }
3691
3692 gclog_or_tty->gclog_stamp();
3693
3694 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3695 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3696 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3697
3698 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3699 }
3700
3701 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3702 if (!G1Log::fine()) {
3703 return;
3704 }
3705
3706 if (G1Log::finer()) {
3707 if (evacuation_failed()) {
3708 gclog_or_tty->print(" (to-space exhausted)");
3709 }
3710 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3711 g1_policy()->print_phases(pause_time_sec);
3712 g1_policy()->print_detailed_heap_transition();
3713 } else {
3714 if (evacuation_failed()) {
3715 gclog_or_tty->print("--");
3716 }
3717 g1_policy()->print_heap_transition();
3718 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3719 }
3720 gclog_or_tty->flush();
3721 }
3722
3723 void G1CollectedHeap::wait_for_root_region_scanning() {
3724 double scan_wait_start = os::elapsedTime();
3725 // We have to wait until the CM threads finish scanning the
3726 // root regions as it's the only way to ensure that all the
3727 // objects on them have been correctly scanned before we start
3728 // moving them during the GC.
3729 bool waited = _cm->root_regions()->wait_until_scan_finished();
3730 double wait_time_ms = 0.0;
3731 if (waited) {
3732 double scan_wait_end = os::elapsedTime();
3733 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3734 }
3735 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3736 }
3737
3738 bool
3739 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3740 assert_at_safepoint(true /* should_be_vm_thread */);
3741 guarantee(!is_gc_active(), "collection is not reentrant");
3742
3743 if (GC_locker::check_active_before_gc()) {
3744 return false;
3745 }
3746
3747 _gc_timer_stw->register_gc_start();
3748
3749 GCIdMark gc_id_mark;
3750 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3751
3752 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3753 ResourceMark rm;
3754
3755 wait_for_root_region_scanning();
3756
3757 G1Log::update_level();
3758 print_heap_before_gc();
3759 trace_heap_before_gc(_gc_tracer_stw);
3760
3761 verify_region_sets_optional();
3762 verify_dirty_young_regions();
3763
3764 // This call will decide whether this pause is an initial-mark
3765 // pause. If it is, during_initial_mark_pause() will return true
3766 // for the duration of this pause.
3767 g1_policy()->decide_on_conc_mark_initiation();
3768
3769 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3770 assert(!collector_state()->during_initial_mark_pause() ||
3771 collector_state()->gcs_are_young(), "sanity");
3772
3773 // We also do not allow mixed GCs during marking.
3774 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3775
3776 // Record whether this pause is an initial mark. When the current
3777 // thread has completed its logging output and it's safe to signal
3778 // the CM thread, the flag's value in the policy has been reset.
3779 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3780
3781 // Inner scope for scope based logging, timers, and stats collection
3782 {
3783 EvacuationInfo evacuation_info;
3784
3785 if (collector_state()->during_initial_mark_pause()) {
3786 // We are about to start a marking cycle, so we increment the
3787 // full collection counter.
3788 increment_old_marking_cycles_started();
3789 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3790 }
3791
3792 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3793
3794 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3795
3796 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3797 workers()->active_workers(),
3798 Threads::number_of_non_daemon_threads());
3799 workers()->set_active_workers(active_workers);
3800
3801 double pause_start_sec = os::elapsedTime();
3802 g1_policy()->note_gc_start(active_workers);
3803 log_gc_header();
3804
3805 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3806 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3807
3808 // If the secondary_free_list is not empty, append it to the
3809 // free_list. No need to wait for the cleanup operation to finish;
3810 // the region allocation code will check the secondary_free_list
3811 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3812 // set, skip this step so that the region allocation code has to
3813 // get entries from the secondary_free_list.
3814 if (!G1StressConcRegionFreeing) {
3815 append_secondary_free_list_if_not_empty_with_lock();
3816 }
3817
3818 assert(check_young_list_well_formed(), "young list should be well formed");
3819
3820 // Don't dynamically change the number of GC threads this early. A value of
3821 // 0 is used to indicate serial work. When parallel work is done,
3822 // it will be set.
3823
3824 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3825 IsGCActiveMark x;
3826
3827 gc_prologue(false);
3828 increment_total_collections(false /* full gc */);
3829 increment_gc_time_stamp();
3830
3831 verify_before_gc();
3832
3833 check_bitmaps("GC Start");
3834
3835 #if defined(COMPILER2) || INCLUDE_JVMCI
3836 DerivedPointerTable::clear();
3837 #endif
3838
3839 // Please see comment in g1CollectedHeap.hpp and
3840 // G1CollectedHeap::ref_processing_init() to see how
3841 // reference processing currently works in G1.
3842
3843 // Enable discovery in the STW reference processor
3844 ref_processor_stw()->enable_discovery();
3845
3846 {
3847 // We want to temporarily turn off discovery by the
3848 // CM ref processor, if necessary, and turn it back on
3849 // on again later if we do. Using a scoped
3850 // NoRefDiscovery object will do this.
3851 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3852
3853 // Forget the current alloc region (we might even choose it to be part
3854 // of the collection set!).
3855 _allocator->release_mutator_alloc_region();
3856
3857 // We should call this after we retire the mutator alloc
3858 // region(s) so that all the ALLOC / RETIRE events are generated
3859 // before the start GC event.
3860 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3861
3862 // This timing is only used by the ergonomics to handle our pause target.
3863 // It is unclear why this should not include the full pause. We will
3864 // investigate this in CR 7178365.
3865 //
3866 // Preserving the old comment here if that helps the investigation:
3867 //
3868 // The elapsed time induced by the start time below deliberately elides
3869 // the possible verification above.
3870 double sample_start_time_sec = os::elapsedTime();
3871
3872 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3873
3874 if (collector_state()->during_initial_mark_pause()) {
3875 concurrent_mark()->checkpointRootsInitialPre();
3876 }
3877
3878 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3879 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3880
3881 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3882
3883 register_humongous_regions_with_cset();
3884
3885 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3886
3887 _cm->note_start_of_gc();
3888 // We call this after finalize_cset() to
3889 // ensure that the CSet has been finalized.
3890 _cm->verify_no_cset_oops();
3891
3892 if (_hr_printer.is_active()) {
3893 HeapRegion* hr = g1_policy()->collection_set();
3894 while (hr != NULL) {
3895 _hr_printer.cset(hr);
3896 hr = hr->next_in_collection_set();
3897 }
3898 }
3899
3900 #ifdef ASSERT
3901 VerifyCSetClosure cl;
3902 collection_set_iterate(&cl);
3903 #endif // ASSERT
3904
3905 // Initialize the GC alloc regions.
3906 _allocator->init_gc_alloc_regions(evacuation_info);
3907
3908 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3909 pre_evacuate_collection_set();
3910
3911 // Actually do the work...
3912 evacuate_collection_set(evacuation_info, &per_thread_states);
3913
3914 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3915
3916 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3917 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3918
3919 eagerly_reclaim_humongous_regions();
3920
3921 g1_policy()->clear_collection_set();
3922
3923 // Start a new incremental collection set for the next pause.
3924 g1_policy()->start_incremental_cset_building();
3925
3926 clear_cset_fast_test();
3927
3928 _young_list->reset_sampled_info();
3929
3930 // Don't check the whole heap at this point as the
3931 // GC alloc regions from this pause have been tagged
3932 // as survivors and moved on to the survivor list.
3933 // Survivor regions will fail the !is_young() check.
3934 assert(check_young_list_empty(false /* check_heap */),
3935 "young list should be empty");
3936
3937 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3938 _young_list->first_survivor_region(),
3939 _young_list->last_survivor_region());
3940
3941 _young_list->reset_auxilary_lists();
3942
3943 if (evacuation_failed()) {
3944 set_used(recalculate_used());
3945 if (_archive_allocator != NULL) {
3946 _archive_allocator->clear_used();
3947 }
3948 for (uint i = 0; i < ParallelGCThreads; i++) {
3949 if (_evacuation_failed_info_array[i].has_failed()) {
3950 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3951 }
3952 }
3953 } else {
3954 // The "used" of the the collection set have already been subtracted
3955 // when they were freed. Add in the bytes evacuated.
3956 increase_used(g1_policy()->bytes_copied_during_gc());
3957 }
3958
3959 if (collector_state()->during_initial_mark_pause()) {
3960 // We have to do this before we notify the CM threads that
3961 // they can start working to make sure that all the
3962 // appropriate initialization is done on the CM object.
3963 concurrent_mark()->checkpointRootsInitialPost();
3964 collector_state()->set_mark_in_progress(true);
3965 // Note that we don't actually trigger the CM thread at
3966 // this point. We do that later when we're sure that
3967 // the current thread has completed its logging output.
3968 }
3969
3970 allocate_dummy_regions();
3971
3972 _allocator->init_mutator_alloc_region();
3973
3974 {
3975 size_t expand_bytes = g1_policy()->expansion_amount();
3976 if (expand_bytes > 0) {
3977 size_t bytes_before = capacity();
3978 // No need for an ergo verbose message here,
3979 // expansion_amount() does this when it returns a value > 0.
3980 double expand_ms;
3981 if (!expand(expand_bytes, &expand_ms)) {
3982 // We failed to expand the heap. Cannot do anything about it.
3983 }
3984 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3985 }
3986 }
3987
3988 // We redo the verification but now wrt to the new CSet which
3989 // has just got initialized after the previous CSet was freed.
3990 _cm->verify_no_cset_oops();
3991 _cm->note_end_of_gc();
3992
3993 // This timing is only used by the ergonomics to handle our pause target.
3994 // It is unclear why this should not include the full pause. We will
3995 // investigate this in CR 7178365.
3996 double sample_end_time_sec = os::elapsedTime();
3997 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3998 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3999 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4000
4001 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4002 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4003
4004 MemoryService::track_memory_usage();
4005
4006 // In prepare_for_verify() below we'll need to scan the deferred
4007 // update buffers to bring the RSets up-to-date if
4008 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4009 // the update buffers we'll probably need to scan cards on the
4010 // regions we just allocated to (i.e., the GC alloc
4011 // regions). However, during the last GC we called
4012 // set_saved_mark() on all the GC alloc regions, so card
4013 // scanning might skip the [saved_mark_word()...top()] area of
4014 // those regions (i.e., the area we allocated objects into
4015 // during the last GC). But it shouldn't. Given that
4016 // saved_mark_word() is conditional on whether the GC time stamp
4017 // on the region is current or not, by incrementing the GC time
4018 // stamp here we invalidate all the GC time stamps on all the
4019 // regions and saved_mark_word() will simply return top() for
4020 // all the regions. This is a nicer way of ensuring this rather
4021 // than iterating over the regions and fixing them. In fact, the
4022 // GC time stamp increment here also ensures that
4023 // saved_mark_word() will return top() between pauses, i.e.,
4024 // during concurrent refinement. So we don't need the
4025 // is_gc_active() check to decided which top to use when
4026 // scanning cards (see CR 7039627).
4027 increment_gc_time_stamp();
4028
4029 verify_after_gc();
4030 check_bitmaps("GC End");
4031
4032 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4033 ref_processor_stw()->verify_no_references_recorded();
4034
4035 // CM reference discovery will be re-enabled if necessary.
4036 }
4037
4038 // We should do this after we potentially expand the heap so
4039 // that all the COMMIT events are generated before the end GC
4040 // event, and after we retire the GC alloc regions so that all
4041 // RETIRE events are generated before the end GC event.
4042 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4043
4044 #ifdef TRACESPINNING
4045 ParallelTaskTerminator::print_termination_counts();
4046 #endif
4047
4048 gc_epilogue(false);
4049 }
4050
4051 // Print the remainder of the GC log output.
4052 log_gc_footer(os::elapsedTime() - pause_start_sec);
4053
4054 // It is not yet to safe to tell the concurrent mark to
4055 // start as we have some optional output below. We don't want the
4056 // output from the concurrent mark thread interfering with this
4057 // logging output either.
4058
4059 _hrm.verify_optional();
4060 verify_region_sets_optional();
4061
4062 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4063 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4064
4065 print_heap_after_gc();
4066 trace_heap_after_gc(_gc_tracer_stw);
4067
4068 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4069 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4070 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4071 // before any GC notifications are raised.
4072 g1mm()->update_sizes();
4073
4074 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4075 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4076 _gc_timer_stw->register_gc_end();
4077 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4078 }
4079 // It should now be safe to tell the concurrent mark thread to start
4080 // without its logging output interfering with the logging output
4081 // that came from the pause.
4082
4083 if (should_start_conc_mark) {
4084 // CAUTION: after the doConcurrentMark() call below,
4085 // the concurrent marking thread(s) could be running
4086 // concurrently with us. Make sure that anything after
4087 // this point does not assume that we are the only GC thread
4088 // running. Note: of course, the actual marking work will
4089 // not start until the safepoint itself is released in
4090 // SuspendibleThreadSet::desynchronize().
4091 doConcurrentMark();
4092 }
4093
4094 return true;
4095 }
4096
4097 void G1CollectedHeap::remove_self_forwarding_pointers() {
4098 double remove_self_forwards_start = os::elapsedTime();
4099
4100 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4101 workers()->run_task(&rsfp_task);
4102
4103 // Now restore saved marks, if any.
4104 for (uint i = 0; i < ParallelGCThreads; i++) {
4105 OopAndMarkOopStack& cur = _preserved_objs[i];
4106 while (!cur.is_empty()) {
4107 OopAndMarkOop elem = cur.pop();
4108 elem.set_mark();
4109 }
4110 cur.clear(true);
4111 }
4112
4113 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4114 }
4115
4116 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4117 if (!_evacuation_failed) {
4118 _evacuation_failed = true;
4119 }
4120
4121 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4122
4123 // We want to call the "for_promotion_failure" version only in the
4124 // case of a promotion failure.
4125 if (m->must_be_preserved_for_promotion_failure(obj)) {
4126 OopAndMarkOop elem(obj, m);
4127 _preserved_objs[worker_id].push(elem);
4128 }
4129 }
4130
4131 class G1ParEvacuateFollowersClosure : public VoidClosure {
4132 private:
4133 double _start_term;
4134 double _term_time;
4135 size_t _term_attempts;
4136
4137 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4138 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4139 protected:
4140 G1CollectedHeap* _g1h;
4141 G1ParScanThreadState* _par_scan_state;
4142 RefToScanQueueSet* _queues;
4143 ParallelTaskTerminator* _terminator;
4144
4145 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4146 RefToScanQueueSet* queues() { return _queues; }
4147 ParallelTaskTerminator* terminator() { return _terminator; }
4148
4149 public:
4150 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4151 G1ParScanThreadState* par_scan_state,
4152 RefToScanQueueSet* queues,
4153 ParallelTaskTerminator* terminator)
4154 : _g1h(g1h), _par_scan_state(par_scan_state),
4155 _queues(queues), _terminator(terminator),
4156 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4157
4158 void do_void();
4159
4160 double term_time() const { return _term_time; }
4161 size_t term_attempts() const { return _term_attempts; }
4162
4163 private:
4164 inline bool offer_termination();
4165 };
4166
4167 bool G1ParEvacuateFollowersClosure::offer_termination() {
4168 G1ParScanThreadState* const pss = par_scan_state();
4169 start_term_time();
4170 const bool res = terminator()->offer_termination();
4171 end_term_time();
4172 return res;
4173 }
4174
4175 void G1ParEvacuateFollowersClosure::do_void() {
4176 G1ParScanThreadState* const pss = par_scan_state();
4177 pss->trim_queue();
4178 do {
4179 pss->steal_and_trim_queue(queues());
4180 } while (!offer_termination());
4181 }
4182
4183 class G1ParTask : public AbstractGangTask {
4184 protected:
4185 G1CollectedHeap* _g1h;
4186 G1ParScanThreadStateSet* _pss;
4187 RefToScanQueueSet* _queues;
4188 G1RootProcessor* _root_processor;
4189 ParallelTaskTerminator _terminator;
4190 uint _n_workers;
4191
4192 public:
4193 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4194 : AbstractGangTask("G1 collection"),
4195 _g1h(g1h),
4196 _pss(per_thread_states),
4197 _queues(task_queues),
4198 _root_processor(root_processor),
4199 _terminator(n_workers, _queues),
4200 _n_workers(n_workers)
4201 {}
4202
4203 void work(uint worker_id) {
4204 if (worker_id >= _n_workers) return; // no work needed this round
4205
4206 double start_sec = os::elapsedTime();
4207 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4208
4209 {
4210 ResourceMark rm;
4211 HandleMark hm;
4212
4213 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4214
4215 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4216 pss->set_ref_processor(rp);
4217
4218 double start_strong_roots_sec = os::elapsedTime();
4219
4220 _root_processor->evacuate_roots(pss->closures(), worker_id);
4221
4222 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4223
4224 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4225 // treating the nmethods visited to act as roots for concurrent marking.
4226 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4227 // objects copied by the current evacuation.
4228 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4229 pss->closures()->weak_codeblobs(),
4230 worker_id);
4231
4232 _pss->add_cards_scanned(worker_id, cards_scanned);
4233
4234 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4235
4236 double term_sec = 0.0;
4237 size_t evac_term_attempts = 0;
4238 {
4239 double start = os::elapsedTime();
4240 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4241 evac.do_void();
4242
4243 evac_term_attempts = evac.term_attempts();
4244 term_sec = evac.term_time();
4245 double elapsed_sec = os::elapsedTime() - start;
4246 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4247 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4248 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4249 }
4250
4251 assert(pss->queue_is_empty(), "should be empty");
4252
4253 if (PrintTerminationStats) {
4254 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4255 size_t lab_waste;
4256 size_t lab_undo_waste;
4257 pss->waste(lab_waste, lab_undo_waste);
4258 _g1h->print_termination_stats(gclog_or_tty,
4259 worker_id,
4260 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4261 strong_roots_sec * 1000.0, /* strong roots time */
4262 term_sec * 1000.0, /* evac term time */
4263 evac_term_attempts, /* evac term attempts */
4264 lab_waste, /* alloc buffer waste */
4265 lab_undo_waste /* undo waste */
4266 );
4267 }
4268
4269 // Close the inner scope so that the ResourceMark and HandleMark
4270 // destructors are executed here and are included as part of the
4271 // "GC Worker Time".
4272 }
4273 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4274 }
4275 };
4276
4277 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4278 st->print_raw_cr("GC Termination Stats");
4279 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4280 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4281 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4282 }
4283
4284 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4285 uint worker_id,
4286 double elapsed_ms,
4287 double strong_roots_ms,
4288 double term_ms,
4289 size_t term_attempts,
4290 size_t alloc_buffer_waste,
4291 size_t undo_waste) const {
4292 st->print_cr("%3d %9.2f %9.2f %6.2f "
4293 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4294 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4295 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4296 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4297 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4298 alloc_buffer_waste * HeapWordSize / K,
4299 undo_waste * HeapWordSize / K);
4300 }
4301
4302 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4303 private:
4304 BoolObjectClosure* _is_alive;
4305 int _initial_string_table_size;
4306 int _initial_symbol_table_size;
4307
4308 bool _process_strings;
4309 int _strings_processed;
4310 int _strings_removed;
4311
4312 bool _process_symbols;
4313 int _symbols_processed;
4314 int _symbols_removed;
4315
4316 public:
4317 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4318 AbstractGangTask("String/Symbol Unlinking"),
4319 _is_alive(is_alive),
4320 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4321 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4322
4323 _initial_string_table_size = StringTable::the_table()->table_size();
4324 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4325 if (process_strings) {
4326 StringTable::clear_parallel_claimed_index();
4327 }
4328 if (process_symbols) {
4329 SymbolTable::clear_parallel_claimed_index();
4330 }
4331 }
4332
4333 ~G1StringSymbolTableUnlinkTask() {
4334 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4335 "claim value %d after unlink less than initial string table size %d",
4336 StringTable::parallel_claimed_index(), _initial_string_table_size);
4337 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4338 "claim value %d after unlink less than initial symbol table size %d",
4339 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4340
4341 if (G1TraceStringSymbolTableScrubbing) {
4342 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4343 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4344 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4345 strings_processed(), strings_removed(),
4346 symbols_processed(), symbols_removed());
4347 }
4348 }
4349
4350 void work(uint worker_id) {
4351 int strings_processed = 0;
4352 int strings_removed = 0;
4353 int symbols_processed = 0;
4354 int symbols_removed = 0;
4355 if (_process_strings) {
4356 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4357 Atomic::add(strings_processed, &_strings_processed);
4358 Atomic::add(strings_removed, &_strings_removed);
4359 }
4360 if (_process_symbols) {
4361 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4362 Atomic::add(symbols_processed, &_symbols_processed);
4363 Atomic::add(symbols_removed, &_symbols_removed);
4364 }
4365 }
4366
4367 size_t strings_processed() const { return (size_t)_strings_processed; }
4368 size_t strings_removed() const { return (size_t)_strings_removed; }
4369
4370 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4371 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4372 };
4373
4374 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4375 private:
4376 static Monitor* _lock;
4377
4378 BoolObjectClosure* const _is_alive;
4379 const bool _unloading_occurred;
4380 const uint _num_workers;
4381
4382 // Variables used to claim nmethods.
4383 nmethod* _first_nmethod;
4384 volatile nmethod* _claimed_nmethod;
4385
4386 // The list of nmethods that need to be processed by the second pass.
4387 volatile nmethod* _postponed_list;
4388 volatile uint _num_entered_barrier;
4389
4390 public:
4391 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4392 _is_alive(is_alive),
4393 _unloading_occurred(unloading_occurred),
4394 _num_workers(num_workers),
4395 _first_nmethod(NULL),
4396 _claimed_nmethod(NULL),
4397 _postponed_list(NULL),
4398 _num_entered_barrier(0)
4399 {
4400 nmethod::increase_unloading_clock();
4401 // Get first alive nmethod
4402 NMethodIterator iter = NMethodIterator();
4403 if(iter.next_alive()) {
4404 _first_nmethod = iter.method();
4405 }
4406 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4407 }
4408
4409 ~G1CodeCacheUnloadingTask() {
4410 CodeCache::verify_clean_inline_caches();
4411
4412 CodeCache::set_needs_cache_clean(false);
4413 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4414
4415 CodeCache::verify_icholder_relocations();
4416 }
4417
4418 private:
4419 void add_to_postponed_list(nmethod* nm) {
4420 nmethod* old;
4421 do {
4422 old = (nmethod*)_postponed_list;
4423 nm->set_unloading_next(old);
4424 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4425 }
4426
4427 void clean_nmethod(nmethod* nm) {
4428 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4429
4430 if (postponed) {
4431 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4432 add_to_postponed_list(nm);
4433 }
4434
4435 // Mark that this thread has been cleaned/unloaded.
4436 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4437 nm->set_unloading_clock(nmethod::global_unloading_clock());
4438 }
4439
4440 void clean_nmethod_postponed(nmethod* nm) {
4441 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4442 }
4443
4444 static const int MaxClaimNmethods = 16;
4445
4446 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4447 nmethod* first;
4448 NMethodIterator last;
4449
4450 do {
4451 *num_claimed_nmethods = 0;
4452
4453 first = (nmethod*)_claimed_nmethod;
4454 last = NMethodIterator(first);
4455
4456 if (first != NULL) {
4457
4458 for (int i = 0; i < MaxClaimNmethods; i++) {
4459 if (!last.next_alive()) {
4460 break;
4461 }
4462 claimed_nmethods[i] = last.method();
4463 (*num_claimed_nmethods)++;
4464 }
4465 }
4466
4467 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4468 }
4469
4470 nmethod* claim_postponed_nmethod() {
4471 nmethod* claim;
4472 nmethod* next;
4473
4474 do {
4475 claim = (nmethod*)_postponed_list;
4476 if (claim == NULL) {
4477 return NULL;
4478 }
4479
4480 next = claim->unloading_next();
4481
4482 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4483
4484 return claim;
4485 }
4486
4487 public:
4488 // Mark that we're done with the first pass of nmethod cleaning.
4489 void barrier_mark(uint worker_id) {
4490 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4491 _num_entered_barrier++;
4492 if (_num_entered_barrier == _num_workers) {
4493 ml.notify_all();
4494 }
4495 }
4496
4497 // See if we have to wait for the other workers to
4498 // finish their first-pass nmethod cleaning work.
4499 void barrier_wait(uint worker_id) {
4500 if (_num_entered_barrier < _num_workers) {
4501 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4502 while (_num_entered_barrier < _num_workers) {
4503 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4504 }
4505 }
4506 }
4507
4508 // Cleaning and unloading of nmethods. Some work has to be postponed
4509 // to the second pass, when we know which nmethods survive.
4510 void work_first_pass(uint worker_id) {
4511 // The first nmethods is claimed by the first worker.
4512 if (worker_id == 0 && _first_nmethod != NULL) {
4513 clean_nmethod(_first_nmethod);
4514 _first_nmethod = NULL;
4515 }
4516
4517 int num_claimed_nmethods;
4518 nmethod* claimed_nmethods[MaxClaimNmethods];
4519
4520 while (true) {
4521 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4522
4523 if (num_claimed_nmethods == 0) {
4524 break;
4525 }
4526
4527 for (int i = 0; i < num_claimed_nmethods; i++) {
4528 clean_nmethod(claimed_nmethods[i]);
4529 }
4530 }
4531 }
4532
4533 void work_second_pass(uint worker_id) {
4534 nmethod* nm;
4535 // Take care of postponed nmethods.
4536 while ((nm = claim_postponed_nmethod()) != NULL) {
4537 clean_nmethod_postponed(nm);
4538 }
4539 }
4540 };
4541
4542 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4543
4544 class G1KlassCleaningTask : public StackObj {
4545 BoolObjectClosure* _is_alive;
4546 volatile jint _clean_klass_tree_claimed;
4547 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4548
4549 public:
4550 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4551 _is_alive(is_alive),
4552 _clean_klass_tree_claimed(0),
4553 _klass_iterator() {
4554 }
4555
4556 private:
4557 bool claim_clean_klass_tree_task() {
4558 if (_clean_klass_tree_claimed) {
4559 return false;
4560 }
4561
4562 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4563 }
4564
4565 InstanceKlass* claim_next_klass() {
4566 Klass* klass;
4567 do {
4568 klass =_klass_iterator.next_klass();
4569 } while (klass != NULL && !klass->is_instance_klass());
4570
4571 // this can be null so don't call InstanceKlass::cast
4572 return static_cast<InstanceKlass*>(klass);
4573 }
4574
4575 public:
4576
4577 void clean_klass(InstanceKlass* ik) {
4578 ik->clean_weak_instanceklass_links(_is_alive);
4579 }
4580
4581 void work() {
4582 ResourceMark rm;
4583
4584 // One worker will clean the subklass/sibling klass tree.
4585 if (claim_clean_klass_tree_task()) {
4586 Klass::clean_subklass_tree(_is_alive);
4587 }
4588
4589 // All workers will help cleaning the classes,
4590 InstanceKlass* klass;
4591 while ((klass = claim_next_klass()) != NULL) {
4592 clean_klass(klass);
4593 }
4594 }
4595 };
4596
4597 // To minimize the remark pause times, the tasks below are done in parallel.
4598 class G1ParallelCleaningTask : public AbstractGangTask {
4599 private:
4600 G1StringSymbolTableUnlinkTask _string_symbol_task;
4601 G1CodeCacheUnloadingTask _code_cache_task;
4602 G1KlassCleaningTask _klass_cleaning_task;
4603
4604 public:
4605 // The constructor is run in the VMThread.
4606 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4607 AbstractGangTask("Parallel Cleaning"),
4608 _string_symbol_task(is_alive, process_strings, process_symbols),
4609 _code_cache_task(num_workers, is_alive, unloading_occurred),
4610 _klass_cleaning_task(is_alive) {
4611 }
4612
4613 // The parallel work done by all worker threads.
4614 void work(uint worker_id) {
4615 // Do first pass of code cache cleaning.
4616 _code_cache_task.work_first_pass(worker_id);
4617
4618 // Let the threads mark that the first pass is done.
4619 _code_cache_task.barrier_mark(worker_id);
4620
4621 // Clean the Strings and Symbols.
4622 _string_symbol_task.work(worker_id);
4623
4624 // Wait for all workers to finish the first code cache cleaning pass.
4625 _code_cache_task.barrier_wait(worker_id);
4626
4627 // Do the second code cache cleaning work, which realize on
4628 // the liveness information gathered during the first pass.
4629 _code_cache_task.work_second_pass(worker_id);
4630
4631 // Clean all klasses that were not unloaded.
4632 _klass_cleaning_task.work();
4633 }
4634 };
4635
4636
4637 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4638 bool process_strings,
4639 bool process_symbols,
4640 bool class_unloading_occurred) {
4641 uint n_workers = workers()->active_workers();
4642
4643 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4644 n_workers, class_unloading_occurred);
4645 workers()->run_task(&g1_unlink_task);
4646 }
4647
4648 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4649 bool process_strings, bool process_symbols) {
4650 {
4651 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4652 workers()->run_task(&g1_unlink_task);
4653 }
4654
4655 if (G1StringDedup::is_enabled()) {
4656 G1StringDedup::unlink(is_alive);
4657 }
4658 }
4659
4660 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4661 private:
4662 DirtyCardQueueSet* _queue;
4663 public:
4664 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4665
4666 virtual void work(uint worker_id) {
4667 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4668 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4669
4670 RedirtyLoggedCardTableEntryClosure cl;
4671 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4672
4673 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4674 }
4675 };
4676
4677 void G1CollectedHeap::redirty_logged_cards() {
4678 double redirty_logged_cards_start = os::elapsedTime();
4679
4680 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4681 dirty_card_queue_set().reset_for_par_iteration();
4682 workers()->run_task(&redirty_task);
4683
4684 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4685 dcq.merge_bufferlists(&dirty_card_queue_set());
4686 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4687
4688 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4689 }
4690
4691 // Weak Reference Processing support
4692
4693 // An always "is_alive" closure that is used to preserve referents.
4694 // If the object is non-null then it's alive. Used in the preservation
4695 // of referent objects that are pointed to by reference objects
4696 // discovered by the CM ref processor.
4697 class G1AlwaysAliveClosure: public BoolObjectClosure {
4698 G1CollectedHeap* _g1;
4699 public:
4700 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4701 bool do_object_b(oop p) {
4702 if (p != NULL) {
4703 return true;
4704 }
4705 return false;
4706 }
4707 };
4708
4709 bool G1STWIsAliveClosure::do_object_b(oop p) {
4710 // An object is reachable if it is outside the collection set,
4711 // or is inside and copied.
4712 return !_g1->is_in_cset(p) || p->is_forwarded();
4713 }
4714
4715 // Non Copying Keep Alive closure
4716 class G1KeepAliveClosure: public OopClosure {
4717 G1CollectedHeap* _g1;
4718 public:
4719 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4720 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4721 void do_oop(oop* p) {
4722 oop obj = *p;
4723 assert(obj != NULL, "the caller should have filtered out NULL values");
4724
4725 const InCSetState cset_state = _g1->in_cset_state(obj);
4726 if (!cset_state.is_in_cset_or_humongous()) {
4727 return;
4728 }
4729 if (cset_state.is_in_cset()) {
4730 assert( obj->is_forwarded(), "invariant" );
4731 *p = obj->forwardee();
4732 } else {
4733 assert(!obj->is_forwarded(), "invariant" );
4734 assert(cset_state.is_humongous(),
4735 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4736 _g1->set_humongous_is_live(obj);
4737 }
4738 }
4739 };
4740
4741 // Copying Keep Alive closure - can be called from both
4742 // serial and parallel code as long as different worker
4743 // threads utilize different G1ParScanThreadState instances
4744 // and different queues.
4745
4746 class G1CopyingKeepAliveClosure: public OopClosure {
4747 G1CollectedHeap* _g1h;
4748 OopClosure* _copy_non_heap_obj_cl;
4749 G1ParScanThreadState* _par_scan_state;
4750
4751 public:
4752 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4753 OopClosure* non_heap_obj_cl,
4754 G1ParScanThreadState* pss):
4755 _g1h(g1h),
4756 _copy_non_heap_obj_cl(non_heap_obj_cl),
4757 _par_scan_state(pss)
4758 {}
4759
4760 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4761 virtual void do_oop( oop* p) { do_oop_work(p); }
4762
4763 template <class T> void do_oop_work(T* p) {
4764 oop obj = oopDesc::load_decode_heap_oop(p);
4765
4766 if (_g1h->is_in_cset_or_humongous(obj)) {
4767 // If the referent object has been forwarded (either copied
4768 // to a new location or to itself in the event of an
4769 // evacuation failure) then we need to update the reference
4770 // field and, if both reference and referent are in the G1
4771 // heap, update the RSet for the referent.
4772 //
4773 // If the referent has not been forwarded then we have to keep
4774 // it alive by policy. Therefore we have copy the referent.
4775 //
4776 // If the reference field is in the G1 heap then we can push
4777 // on the PSS queue. When the queue is drained (after each
4778 // phase of reference processing) the object and it's followers
4779 // will be copied, the reference field set to point to the
4780 // new location, and the RSet updated. Otherwise we need to
4781 // use the the non-heap or metadata closures directly to copy
4782 // the referent object and update the pointer, while avoiding
4783 // updating the RSet.
4784
4785 if (_g1h->is_in_g1_reserved(p)) {
4786 _par_scan_state->push_on_queue(p);
4787 } else {
4788 assert(!Metaspace::contains((const void*)p),
4789 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4790 _copy_non_heap_obj_cl->do_oop(p);
4791 }
4792 }
4793 }
4794 };
4795
4796 // Serial drain queue closure. Called as the 'complete_gc'
4797 // closure for each discovered list in some of the
4798 // reference processing phases.
4799
4800 class G1STWDrainQueueClosure: public VoidClosure {
4801 protected:
4802 G1CollectedHeap* _g1h;
4803 G1ParScanThreadState* _par_scan_state;
4804
4805 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4806
4807 public:
4808 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4809 _g1h(g1h),
4810 _par_scan_state(pss)
4811 { }
4812
4813 void do_void() {
4814 G1ParScanThreadState* const pss = par_scan_state();
4815 pss->trim_queue();
4816 }
4817 };
4818
4819 // Parallel Reference Processing closures
4820
4821 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4822 // processing during G1 evacuation pauses.
4823
4824 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4825 private:
4826 G1CollectedHeap* _g1h;
4827 G1ParScanThreadStateSet* _pss;
4828 RefToScanQueueSet* _queues;
4829 WorkGang* _workers;
4830 uint _active_workers;
4831
4832 public:
4833 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4834 G1ParScanThreadStateSet* per_thread_states,
4835 WorkGang* workers,
4836 RefToScanQueueSet *task_queues,
4837 uint n_workers) :
4838 _g1h(g1h),
4839 _pss(per_thread_states),
4840 _queues(task_queues),
4841 _workers(workers),
4842 _active_workers(n_workers)
4843 {
4844 assert(n_workers > 0, "shouldn't call this otherwise");
4845 }
4846
4847 // Executes the given task using concurrent marking worker threads.
4848 virtual void execute(ProcessTask& task);
4849 virtual void execute(EnqueueTask& task);
4850 };
4851
4852 // Gang task for possibly parallel reference processing
4853
4854 class G1STWRefProcTaskProxy: public AbstractGangTask {
4855 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4856 ProcessTask& _proc_task;
4857 G1CollectedHeap* _g1h;
4858 G1ParScanThreadStateSet* _pss;
4859 RefToScanQueueSet* _task_queues;
4860 ParallelTaskTerminator* _terminator;
4861
4862 public:
4863 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4864 G1CollectedHeap* g1h,
4865 G1ParScanThreadStateSet* per_thread_states,
4866 RefToScanQueueSet *task_queues,
4867 ParallelTaskTerminator* terminator) :
4868 AbstractGangTask("Process reference objects in parallel"),
4869 _proc_task(proc_task),
4870 _g1h(g1h),
4871 _pss(per_thread_states),
4872 _task_queues(task_queues),
4873 _terminator(terminator)
4874 {}
4875
4876 virtual void work(uint worker_id) {
4877 // The reference processing task executed by a single worker.
4878 ResourceMark rm;
4879 HandleMark hm;
4880
4881 G1STWIsAliveClosure is_alive(_g1h);
4882
4883 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4884 pss->set_ref_processor(NULL);
4885
4886 // Keep alive closure.
4887 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4888
4889 // Complete GC closure
4890 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4891
4892 // Call the reference processing task's work routine.
4893 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4894
4895 // Note we cannot assert that the refs array is empty here as not all
4896 // of the processing tasks (specifically phase2 - pp2_work) execute
4897 // the complete_gc closure (which ordinarily would drain the queue) so
4898 // the queue may not be empty.
4899 }
4900 };
4901
4902 // Driver routine for parallel reference processing.
4903 // Creates an instance of the ref processing gang
4904 // task and has the worker threads execute it.
4905 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4906 assert(_workers != NULL, "Need parallel worker threads.");
4907
4908 ParallelTaskTerminator terminator(_active_workers, _queues);
4909 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4910
4911 _workers->run_task(&proc_task_proxy);
4912 }
4913
4914 // Gang task for parallel reference enqueueing.
4915
4916 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4917 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4918 EnqueueTask& _enq_task;
4919
4920 public:
4921 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4922 AbstractGangTask("Enqueue reference objects in parallel"),
4923 _enq_task(enq_task)
4924 { }
4925
4926 virtual void work(uint worker_id) {
4927 _enq_task.work(worker_id);
4928 }
4929 };
4930
4931 // Driver routine for parallel reference enqueueing.
4932 // Creates an instance of the ref enqueueing gang
4933 // task and has the worker threads execute it.
4934
4935 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4936 assert(_workers != NULL, "Need parallel worker threads.");
4937
4938 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4939
4940 _workers->run_task(&enq_task_proxy);
4941 }
4942
4943 // End of weak reference support closures
4944
4945 // Abstract task used to preserve (i.e. copy) any referent objects
4946 // that are in the collection set and are pointed to by reference
4947 // objects discovered by the CM ref processor.
4948
4949 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4950 protected:
4951 G1CollectedHeap* _g1h;
4952 G1ParScanThreadStateSet* _pss;
4953 RefToScanQueueSet* _queues;
4954 ParallelTaskTerminator _terminator;
4955 uint _n_workers;
4956
4957 public:
4958 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4959 AbstractGangTask("ParPreserveCMReferents"),
4960 _g1h(g1h),
4961 _pss(per_thread_states),
4962 _queues(task_queues),
4963 _terminator(workers, _queues),
4964 _n_workers(workers)
4965 { }
4966
4967 void work(uint worker_id) {
4968 ResourceMark rm;
4969 HandleMark hm;
4970
4971 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4972 pss->set_ref_processor(NULL);
4973 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4974
4975 // Is alive closure
4976 G1AlwaysAliveClosure always_alive(_g1h);
4977
4978 // Copying keep alive closure. Applied to referent objects that need
4979 // to be copied.
4980 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4981
4982 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4983
4984 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4985 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4986
4987 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4988 // So this must be true - but assert just in case someone decides to
4989 // change the worker ids.
4990 assert(worker_id < limit, "sanity");
4991 assert(!rp->discovery_is_atomic(), "check this code");
4992
4993 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4994 for (uint idx = worker_id; idx < limit; idx += stride) {
4995 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4996
4997 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4998 while (iter.has_next()) {
4999 // Since discovery is not atomic for the CM ref processor, we
5000 // can see some null referent objects.
5001 iter.load_ptrs(DEBUG_ONLY(true));
5002 oop ref = iter.obj();
5003
5004 // This will filter nulls.
5005 if (iter.is_referent_alive()) {
5006 iter.make_referent_alive();
5007 }
5008 iter.move_to_next();
5009 }
5010 }
5011
5012 // Drain the queue - which may cause stealing
5013 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5014 drain_queue.do_void();
5015 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5016 assert(pss->queue_is_empty(), "should be");
5017 }
5018 };
5019
5020 // Weak Reference processing during an evacuation pause (part 1).
5021 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5022 double ref_proc_start = os::elapsedTime();
5023
5024 ReferenceProcessor* rp = _ref_processor_stw;
5025 assert(rp->discovery_enabled(), "should have been enabled");
5026
5027 // Any reference objects, in the collection set, that were 'discovered'
5028 // by the CM ref processor should have already been copied (either by
5029 // applying the external root copy closure to the discovered lists, or
5030 // by following an RSet entry).
5031 //
5032 // But some of the referents, that are in the collection set, that these
5033 // reference objects point to may not have been copied: the STW ref
5034 // processor would have seen that the reference object had already
5035 // been 'discovered' and would have skipped discovering the reference,
5036 // but would not have treated the reference object as a regular oop.
5037 // As a result the copy closure would not have been applied to the
5038 // referent object.
5039 //
5040 // We need to explicitly copy these referent objects - the references
5041 // will be processed at the end of remarking.
5042 //
5043 // We also need to do this copying before we process the reference
5044 // objects discovered by the STW ref processor in case one of these
5045 // referents points to another object which is also referenced by an
5046 // object discovered by the STW ref processor.
5047
5048 uint no_of_gc_workers = workers()->active_workers();
5049
5050 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5051 per_thread_states,
5052 no_of_gc_workers,
5053 _task_queues);
5054
5055 workers()->run_task(&keep_cm_referents);
5056
5057 // Closure to test whether a referent is alive.
5058 G1STWIsAliveClosure is_alive(this);
5059
5060 // Even when parallel reference processing is enabled, the processing
5061 // of JNI refs is serial and performed serially by the current thread
5062 // rather than by a worker. The following PSS will be used for processing
5063 // JNI refs.
5064
5065 // Use only a single queue for this PSS.
5066 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5067 pss->set_ref_processor(NULL);
5068 assert(pss->queue_is_empty(), "pre-condition");
5069
5070 // Keep alive closure.
5071 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5072
5073 // Serial Complete GC closure
5074 G1STWDrainQueueClosure drain_queue(this, pss);
5075
5076 // Setup the soft refs policy...
5077 rp->setup_policy(false);
5078
5079 ReferenceProcessorStats stats;
5080 if (!rp->processing_is_mt()) {
5081 // Serial reference processing...
5082 stats = rp->process_discovered_references(&is_alive,
5083 &keep_alive,
5084 &drain_queue,
5085 NULL,
5086 _gc_timer_stw);
5087 } else {
5088 // Parallel reference processing
5089 assert(rp->num_q() == no_of_gc_workers, "sanity");
5090 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5091
5092 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5093 stats = rp->process_discovered_references(&is_alive,
5094 &keep_alive,
5095 &drain_queue,
5096 &par_task_executor,
5097 _gc_timer_stw);
5098 }
5099
5100 _gc_tracer_stw->report_gc_reference_stats(stats);
5101
5102 // We have completed copying any necessary live referent objects.
5103 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5104
5105 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5106 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5107 }
5108
5109 // Weak Reference processing during an evacuation pause (part 2).
5110 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5111 double ref_enq_start = os::elapsedTime();
5112
5113 ReferenceProcessor* rp = _ref_processor_stw;
5114 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5115
5116 // Now enqueue any remaining on the discovered lists on to
5117 // the pending list.
5118 if (!rp->processing_is_mt()) {
5119 // Serial reference processing...
5120 rp->enqueue_discovered_references();
5121 } else {
5122 // Parallel reference enqueueing
5123
5124 uint n_workers = workers()->active_workers();
5125
5126 assert(rp->num_q() == n_workers, "sanity");
5127 assert(n_workers <= rp->max_num_q(), "sanity");
5128
5129 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5130 rp->enqueue_discovered_references(&par_task_executor);
5131 }
5132
5133 rp->verify_no_references_recorded();
5134 assert(!rp->discovery_enabled(), "should have been disabled");
5135
5136 // FIXME
5137 // CM's reference processing also cleans up the string and symbol tables.
5138 // Should we do that here also? We could, but it is a serial operation
5139 // and could significantly increase the pause time.
5140
5141 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5142 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5143 }
5144
5145 void G1CollectedHeap::pre_evacuate_collection_set() {
5146 _expand_heap_after_alloc_failure = true;
5147 _evacuation_failed = false;
5148
5149 // Disable the hot card cache.
5150 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5151 hot_card_cache->reset_hot_cache_claimed_index();
5152 hot_card_cache->set_use_cache(false);
5153
5154 }
5155
5156 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5157 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5158
5159 // Should G1EvacuationFailureALot be in effect for this GC?
5160 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5161
5162 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5163 double start_par_time_sec = os::elapsedTime();
5164 double end_par_time_sec;
5165
5166 {
5167 const uint n_workers = workers()->active_workers();
5168 G1RootProcessor root_processor(this, n_workers);
5169 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5170 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5171 if (collector_state()->during_initial_mark_pause()) {
5172 ClassLoaderDataGraph::clear_claimed_marks();
5173 }
5174
5175 // The individual threads will set their evac-failure closures.
5176 if (PrintTerminationStats) {
5177 print_termination_stats_hdr(gclog_or_tty);
5178 }
5179
5180 workers()->run_task(&g1_par_task);
5181 end_par_time_sec = os::elapsedTime();
5182
5183 // Closing the inner scope will execute the destructor
5184 // for the G1RootProcessor object. We record the current
5185 // elapsed time before closing the scope so that time
5186 // taken for the destructor is NOT included in the
5187 // reported parallel time.
5188 }
5189
5190 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5191
5192 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5193 phase_times->record_par_time(par_time_ms);
5194
5195 double code_root_fixup_time_ms =
5196 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5197 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5198
5199 // Process any discovered reference objects - we have
5200 // to do this _before_ we retire the GC alloc regions
5201 // as we may have to copy some 'reachable' referent
5202 // objects (and their reachable sub-graphs) that were
5203 // not copied during the pause.
5204 process_discovered_references(per_thread_states);
5205
5206 if (G1StringDedup::is_enabled()) {
5207 double fixup_start = os::elapsedTime();
5208
5209 G1STWIsAliveClosure is_alive(this);
5210 G1KeepAliveClosure keep_alive(this);
5211 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5212
5213 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5214 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5215 }
5216
5217 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5218
5219 if (evacuation_failed()) {
5220 remove_self_forwarding_pointers();
5221
5222 // Reset the G1EvacuationFailureALot counters and flags
5223 // Note: the values are reset only when an actual
5224 // evacuation failure occurs.
5225 NOT_PRODUCT(reset_evacuation_should_fail();)
5226 }
5227
5228 // Enqueue any remaining references remaining on the STW
5229 // reference processor's discovered lists. We need to do
5230 // this after the card table is cleaned (and verified) as
5231 // the act of enqueueing entries on to the pending list
5232 // will log these updates (and dirty their associated
5233 // cards). We need these updates logged to update any
5234 // RSets.
5235 enqueue_discovered_references(per_thread_states);
5236 }
5237
5238 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5239 _allocator->release_gc_alloc_regions(evacuation_info);
5240
5241 per_thread_states->flush();
5242
5243 record_obj_copy_mem_stats();
5244
5245 // Reset and re-enable the hot card cache.
5246 // Note the counts for the cards in the regions in the
5247 // collection set are reset when the collection set is freed.
5248 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5249 hot_card_cache->reset_hot_cache();
5250 hot_card_cache->set_use_cache(true);
5251
5252 purge_code_root_memory();
5253
5254 redirty_logged_cards();
5255 #if defined(COMPILER2) || INCLUDE_JVMCI
5256 DerivedPointerTable::update_pointers();
5257 #endif
5258 }
5259
5260 void G1CollectedHeap::record_obj_copy_mem_stats() {
5261 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5262 create_g1_evac_summary(&_old_evac_stats));
5263 }
5264
5265 void G1CollectedHeap::free_region(HeapRegion* hr,
5266 FreeRegionList* free_list,
5267 bool par,
5268 bool locked) {
5269 assert(!hr->is_free(), "the region should not be free");
5270 assert(!hr->is_empty(), "the region should not be empty");
5271 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5272 assert(free_list != NULL, "pre-condition");
5273
5274 if (G1VerifyBitmaps) {
5275 MemRegion mr(hr->bottom(), hr->end());
5276 concurrent_mark()->clearRangePrevBitmap(mr);
5277 }
5278
5279 // Clear the card counts for this region.
5280 // Note: we only need to do this if the region is not young
5281 // (since we don't refine cards in young regions).
5282 if (!hr->is_young()) {
5283 _cg1r->hot_card_cache()->reset_card_counts(hr);
5284 }
5285 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5286 free_list->add_ordered(hr);
5287 }
5288
5289 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5290 FreeRegionList* free_list,
5291 bool par) {
5292 assert(hr->is_humongous(), "this is only for humongous regions");
5293 assert(free_list != NULL, "pre-condition");
5294 hr->clear_humongous();
5295 free_region(hr, free_list, par);
5296 }
5297
5298 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5299 const HeapRegionSetCount& humongous_regions_removed) {
5300 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5301 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5302 _old_set.bulk_remove(old_regions_removed);
5303 _humongous_set.bulk_remove(humongous_regions_removed);
5304 }
5305
5306 }
5307
5308 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5309 assert(list != NULL, "list can't be null");
5310 if (!list->is_empty()) {
5311 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5312 _hrm.insert_list_into_free_list(list);
5313 }
5314 }
5315
5316 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5317 decrease_used(bytes);
5318 }
5319
5320 class G1ParCleanupCTTask : public AbstractGangTask {
5321 G1SATBCardTableModRefBS* _ct_bs;
5322 G1CollectedHeap* _g1h;
5323 HeapRegion* volatile _su_head;
5324 public:
5325 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5326 G1CollectedHeap* g1h) :
5327 AbstractGangTask("G1 Par Cleanup CT Task"),
5328 _ct_bs(ct_bs), _g1h(g1h) { }
5329
5330 void work(uint worker_id) {
5331 HeapRegion* r;
5332 while (r = _g1h->pop_dirty_cards_region()) {
5333 clear_cards(r);
5334 }
5335 }
5336
5337 void clear_cards(HeapRegion* r) {
5338 // Cards of the survivors should have already been dirtied.
5339 if (!r->is_survivor()) {
5340 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5341 }
5342 }
5343 };
5344
5345 #ifndef PRODUCT
5346 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5347 G1CollectedHeap* _g1h;
5348 G1SATBCardTableModRefBS* _ct_bs;
5349 public:
5350 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5351 : _g1h(g1h), _ct_bs(ct_bs) { }
5352 virtual bool doHeapRegion(HeapRegion* r) {
5353 if (r->is_survivor()) {
5354 _g1h->verify_dirty_region(r);
5355 } else {
5356 _g1h->verify_not_dirty_region(r);
5357 }
5358 return false;
5359 }
5360 };
5361
5362 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5363 // All of the region should be clean.
5364 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5365 MemRegion mr(hr->bottom(), hr->end());
5366 ct_bs->verify_not_dirty_region(mr);
5367 }
5368
5369 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5370 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5371 // dirty allocated blocks as they allocate them. The thread that
5372 // retires each region and replaces it with a new one will do a
5373 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5374 // not dirty that area (one less thing to have to do while holding
5375 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5376 // is dirty.
5377 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5378 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5379 if (hr->is_young()) {
5380 ct_bs->verify_g1_young_region(mr);
5381 } else {
5382 ct_bs->verify_dirty_region(mr);
5383 }
5384 }
5385
5386 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5387 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5388 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5389 verify_dirty_region(hr);
5390 }
5391 }
5392
5393 void G1CollectedHeap::verify_dirty_young_regions() {
5394 verify_dirty_young_list(_young_list->first_region());
5395 }
5396
5397 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5398 HeapWord* tams, HeapWord* end) {
5399 guarantee(tams <= end,
5400 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5401 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5402 if (result < end) {
5403 gclog_or_tty->cr();
5404 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5405 bitmap_name, p2i(result));
5406 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5407 bitmap_name, p2i(tams), p2i(end));
5408 return false;
5409 }
5410 return true;
5411 }
5412
5413 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5414 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5415 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5416
5417 HeapWord* bottom = hr->bottom();
5418 HeapWord* ptams = hr->prev_top_at_mark_start();
5419 HeapWord* ntams = hr->next_top_at_mark_start();
5420 HeapWord* end = hr->end();
5421
5422 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5423
5424 bool res_n = true;
5425 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5426 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5427 // if we happen to be in that state.
5428 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5429 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5430 }
5431 if (!res_p || !res_n) {
5432 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5433 HR_FORMAT_PARAMS(hr));
5434 gclog_or_tty->print_cr("#### Caller: %s", caller);
5435 return false;
5436 }
5437 return true;
5438 }
5439
5440 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5441 if (!G1VerifyBitmaps) return;
5442
5443 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5444 }
5445
5446 class G1VerifyBitmapClosure : public HeapRegionClosure {
5447 private:
5448 const char* _caller;
5449 G1CollectedHeap* _g1h;
5450 bool _failures;
5451
5452 public:
5453 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5454 _caller(caller), _g1h(g1h), _failures(false) { }
5455
5456 bool failures() { return _failures; }
5457
5458 virtual bool doHeapRegion(HeapRegion* hr) {
5459 bool result = _g1h->verify_bitmaps(_caller, hr);
5460 if (!result) {
5461 _failures = true;
5462 }
5463 return false;
5464 }
5465 };
5466
5467 void G1CollectedHeap::check_bitmaps(const char* caller) {
5468 if (!G1VerifyBitmaps) return;
5469
5470 G1VerifyBitmapClosure cl(caller, this);
5471 heap_region_iterate(&cl);
5472 guarantee(!cl.failures(), "bitmap verification");
5473 }
5474
5475 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5476 private:
5477 bool _failures;
5478 public:
5479 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5480
5481 virtual bool doHeapRegion(HeapRegion* hr) {
5482 uint i = hr->hrm_index();
5483 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5484 if (hr->is_humongous()) {
5485 if (hr->in_collection_set()) {
5486 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5487 _failures = true;
5488 return true;
5489 }
5490 if (cset_state.is_in_cset()) {
5491 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5492 _failures = true;
5493 return true;
5494 }
5495 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5496 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5497 _failures = true;
5498 return true;
5499 }
5500 } else {
5501 if (cset_state.is_humongous()) {
5502 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5503 _failures = true;
5504 return true;
5505 }
5506 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5507 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5508 hr->in_collection_set(), cset_state.value(), i);
5509 _failures = true;
5510 return true;
5511 }
5512 if (cset_state.is_in_cset()) {
5513 if (hr->is_young() != (cset_state.is_young())) {
5514 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5515 hr->is_young(), cset_state.value(), i);
5516 _failures = true;
5517 return true;
5518 }
5519 if (hr->is_old() != (cset_state.is_old())) {
5520 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5521 hr->is_old(), cset_state.value(), i);
5522 _failures = true;
5523 return true;
5524 }
5525 }
5526 }
5527 return false;
5528 }
5529
5530 bool failures() const { return _failures; }
5531 };
5532
5533 bool G1CollectedHeap::check_cset_fast_test() {
5534 G1CheckCSetFastTableClosure cl;
5535 _hrm.iterate(&cl);
5536 return !cl.failures();
5537 }
5538 #endif // PRODUCT
5539
5540 void G1CollectedHeap::cleanUpCardTable() {
5541 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5542 double start = os::elapsedTime();
5543
5544 {
5545 // Iterate over the dirty cards region list.
5546 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5547
5548 workers()->run_task(&cleanup_task);
5549 #ifndef PRODUCT
5550 if (G1VerifyCTCleanup || VerifyAfterGC) {
5551 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5552 heap_region_iterate(&cleanup_verifier);
5553 }
5554 #endif
5555 }
5556
5557 double elapsed = os::elapsedTime() - start;
5558 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5559 }
5560
5561 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5562 size_t pre_used = 0;
5563 FreeRegionList local_free_list("Local List for CSet Freeing");
5564
5565 double young_time_ms = 0.0;
5566 double non_young_time_ms = 0.0;
5567
5568 // Since the collection set is a superset of the the young list,
5569 // all we need to do to clear the young list is clear its
5570 // head and length, and unlink any young regions in the code below
5571 _young_list->clear();
5572
5573 G1CollectorPolicy* policy = g1_policy();
5574
5575 double start_sec = os::elapsedTime();
5576 bool non_young = true;
5577
5578 HeapRegion* cur = cs_head;
5579 int age_bound = -1;
5580 size_t rs_lengths = 0;
5581
5582 while (cur != NULL) {
5583 assert(!is_on_master_free_list(cur), "sanity");
5584 if (non_young) {
5585 if (cur->is_young()) {
5586 double end_sec = os::elapsedTime();
5587 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5588 non_young_time_ms += elapsed_ms;
5589
5590 start_sec = os::elapsedTime();
5591 non_young = false;
5592 }
5593 } else {
5594 if (!cur->is_young()) {
5595 double end_sec = os::elapsedTime();
5596 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5597 young_time_ms += elapsed_ms;
5598
5599 start_sec = os::elapsedTime();
5600 non_young = true;
5601 }
5602 }
5603
5604 rs_lengths += cur->rem_set()->occupied_locked();
5605
5606 HeapRegion* next = cur->next_in_collection_set();
5607 assert(cur->in_collection_set(), "bad CS");
5608 cur->set_next_in_collection_set(NULL);
5609 clear_in_cset(cur);
5610
5611 if (cur->is_young()) {
5612 int index = cur->young_index_in_cset();
5613 assert(index != -1, "invariant");
5614 assert((uint) index < policy->young_cset_region_length(), "invariant");
5615 size_t words_survived = surviving_young_words[index];
5616 cur->record_surv_words_in_group(words_survived);
5617
5618 // At this point the we have 'popped' cur from the collection set
5619 // (linked via next_in_collection_set()) but it is still in the
5620 // young list (linked via next_young_region()). Clear the
5621 // _next_young_region field.
5622 cur->set_next_young_region(NULL);
5623 } else {
5624 int index = cur->young_index_in_cset();
5625 assert(index == -1, "invariant");
5626 }
5627
5628 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5629 (!cur->is_young() && cur->young_index_in_cset() == -1),
5630 "invariant" );
5631
5632 if (!cur->evacuation_failed()) {
5633 MemRegion used_mr = cur->used_region();
5634
5635 // And the region is empty.
5636 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5637 pre_used += cur->used();
5638 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5639 } else {
5640 cur->uninstall_surv_rate_group();
5641 if (cur->is_young()) {
5642 cur->set_young_index_in_cset(-1);
5643 }
5644 cur->set_evacuation_failed(false);
5645 // The region is now considered to be old.
5646 cur->set_old();
5647 // Do some allocation statistics accounting. Regions that failed evacuation
5648 // are always made old, so there is no need to update anything in the young
5649 // gen statistics, but we need to update old gen statistics.
5650 size_t used_words = cur->marked_bytes() / HeapWordSize;
5651 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5652 _old_set.add(cur);
5653 evacuation_info.increment_collectionset_used_after(cur->used());
5654 }
5655 cur = next;
5656 }
5657
5658 evacuation_info.set_regions_freed(local_free_list.length());
5659 policy->record_max_rs_lengths(rs_lengths);
5660 policy->cset_regions_freed();
5661
5662 double end_sec = os::elapsedTime();
5663 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5664
5665 if (non_young) {
5666 non_young_time_ms += elapsed_ms;
5667 } else {
5668 young_time_ms += elapsed_ms;
5669 }
5670
5671 prepend_to_freelist(&local_free_list);
5672 decrement_summary_bytes(pre_used);
5673 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5674 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5675 }
5676
5677 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5678 private:
5679 FreeRegionList* _free_region_list;
5680 HeapRegionSet* _proxy_set;
5681 HeapRegionSetCount _humongous_regions_removed;
5682 size_t _freed_bytes;
5683 public:
5684
5685 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5686 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5687 }
5688
5689 virtual bool doHeapRegion(HeapRegion* r) {
5690 if (!r->is_starts_humongous()) {
5691 return false;
5692 }
5693
5694 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5695
5696 oop obj = (oop)r->bottom();
5697 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5698
5699 // The following checks whether the humongous object is live are sufficient.
5700 // The main additional check (in addition to having a reference from the roots
5701 // or the young gen) is whether the humongous object has a remembered set entry.
5702 //
5703 // A humongous object cannot be live if there is no remembered set for it
5704 // because:
5705 // - there can be no references from within humongous starts regions referencing
5706 // the object because we never allocate other objects into them.
5707 // (I.e. there are no intra-region references that may be missed by the
5708 // remembered set)
5709 // - as soon there is a remembered set entry to the humongous starts region
5710 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5711 // until the end of a concurrent mark.
5712 //
5713 // It is not required to check whether the object has been found dead by marking
5714 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5715 // all objects allocated during that time are considered live.
5716 // SATB marking is even more conservative than the remembered set.
5717 // So if at this point in the collection there is no remembered set entry,
5718 // nobody has a reference to it.
5719 // At the start of collection we flush all refinement logs, and remembered sets
5720 // are completely up-to-date wrt to references to the humongous object.
5721 //
5722 // Other implementation considerations:
5723 // - never consider object arrays at this time because they would pose
5724 // considerable effort for cleaning up the the remembered sets. This is
5725 // required because stale remembered sets might reference locations that
5726 // are currently allocated into.
5727 uint region_idx = r->hrm_index();
5728 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5729 !r->rem_set()->is_empty()) {
5730
5731 if (G1TraceEagerReclaimHumongousObjects) {
5732 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",
5733 region_idx,
5734 (size_t)obj->size() * HeapWordSize,
5735 p2i(r->bottom()),
5736 r->rem_set()->occupied(),
5737 r->rem_set()->strong_code_roots_list_length(),
5738 next_bitmap->isMarked(r->bottom()),
5739 g1h->is_humongous_reclaim_candidate(region_idx),
5740 obj->is_typeArray()
5741 );
5742 }
5743
5744 return false;
5745 }
5746
5747 guarantee(obj->is_typeArray(),
5748 "Only eagerly reclaiming type arrays is supported, but the object "
5749 PTR_FORMAT " is not.", p2i(r->bottom()));
5750
5751 if (G1TraceEagerReclaimHumongousObjects) {
5752 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",
5753 region_idx,
5754 (size_t)obj->size() * HeapWordSize,
5755 p2i(r->bottom()),
5756 r->rem_set()->occupied(),
5757 r->rem_set()->strong_code_roots_list_length(),
5758 next_bitmap->isMarked(r->bottom()),
5759 g1h->is_humongous_reclaim_candidate(region_idx),
5760 obj->is_typeArray()
5761 );
5762 }
5763 // Need to clear mark bit of the humongous object if already set.
5764 if (next_bitmap->isMarked(r->bottom())) {
5765 next_bitmap->clear(r->bottom());
5766 }
5767 do {
5768 HeapRegion* next = g1h->next_region_by_index(r);
5769 _freed_bytes += r->used();
5770 r->set_containing_set(NULL);
5771 _humongous_regions_removed.increment(1u, r->capacity());
5772 g1h->free_humongous_region(r, _free_region_list, false);
5773 r = next;
5774 } while (r != NULL && r->is_continues_humongous());
5775
5776 return false;
5777 }
5778
5779 HeapRegionSetCount& humongous_free_count() {
5780 return _humongous_regions_removed;
5781 }
5782
5783 size_t bytes_freed() const {
5784 return _freed_bytes;
5785 }
5786
5787 size_t humongous_reclaimed() const {
5788 return _humongous_regions_removed.length();
5789 }
5790 };
5791
5792 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5793 assert_at_safepoint(true);
5794
5795 if (!G1EagerReclaimHumongousObjects ||
5796 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5797 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5798 return;
5799 }
5800
5801 double start_time = os::elapsedTime();
5802
5803 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5804
5805 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5806 heap_region_iterate(&cl);
5807
5808 HeapRegionSetCount empty_set;
5809 remove_from_old_sets(empty_set, cl.humongous_free_count());
5810
5811 G1HRPrinter* hrp = hr_printer();
5812 if (hrp->is_active()) {
5813 FreeRegionListIterator iter(&local_cleanup_list);
5814 while (iter.more_available()) {
5815 HeapRegion* hr = iter.get_next();
5816 hrp->cleanup(hr);
5817 }
5818 }
5819
5820 prepend_to_freelist(&local_cleanup_list);
5821 decrement_summary_bytes(cl.bytes_freed());
5822
5823 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5824 cl.humongous_reclaimed());
5825 }
5826
5827 // This routine is similar to the above but does not record
5828 // any policy statistics or update free lists; we are abandoning
5829 // the current incremental collection set in preparation of a
5830 // full collection. After the full GC we will start to build up
5831 // the incremental collection set again.
5832 // This is only called when we're doing a full collection
5833 // and is immediately followed by the tearing down of the young list.
5834
5835 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5836 HeapRegion* cur = cs_head;
5837
5838 while (cur != NULL) {
5839 HeapRegion* next = cur->next_in_collection_set();
5840 assert(cur->in_collection_set(), "bad CS");
5841 cur->set_next_in_collection_set(NULL);
5842 clear_in_cset(cur);
5843 cur->set_young_index_in_cset(-1);
5844 cur = next;
5845 }
5846 }
5847
5848 void G1CollectedHeap::set_free_regions_coming() {
5849 if (G1ConcRegionFreeingVerbose) {
5850 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5851 "setting free regions coming");
5852 }
5853
5854 assert(!free_regions_coming(), "pre-condition");
5855 _free_regions_coming = true;
5856 }
5857
5858 void G1CollectedHeap::reset_free_regions_coming() {
5859 assert(free_regions_coming(), "pre-condition");
5860
5861 {
5862 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5863 _free_regions_coming = false;
5864 SecondaryFreeList_lock->notify_all();
5865 }
5866
5867 if (G1ConcRegionFreeingVerbose) {
5868 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5869 "reset free regions coming");
5870 }
5871 }
5872
5873 void G1CollectedHeap::wait_while_free_regions_coming() {
5874 // Most of the time we won't have to wait, so let's do a quick test
5875 // first before we take the lock.
5876 if (!free_regions_coming()) {
5877 return;
5878 }
5879
5880 if (G1ConcRegionFreeingVerbose) {
5881 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5882 "waiting for free regions");
5883 }
5884
5885 {
5886 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5887 while (free_regions_coming()) {
5888 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5889 }
5890 }
5891
5892 if (G1ConcRegionFreeingVerbose) {
5893 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5894 "done waiting for free regions");
5895 }
5896 }
5897
5898 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5899 return _allocator->is_retained_old_region(hr);
5900 }
5901
5902 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5903 _young_list->push_region(hr);
5904 }
5905
5906 class NoYoungRegionsClosure: public HeapRegionClosure {
5907 private:
5908 bool _success;
5909 public:
5910 NoYoungRegionsClosure() : _success(true) { }
5911 bool doHeapRegion(HeapRegion* r) {
5912 if (r->is_young()) {
5913 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5914 p2i(r->bottom()), p2i(r->end()));
5915 _success = false;
5916 }
5917 return false;
5918 }
5919 bool success() { return _success; }
5920 };
5921
5922 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5923 bool ret = _young_list->check_list_empty(check_sample);
5924
5925 if (check_heap) {
5926 NoYoungRegionsClosure closure;
5927 heap_region_iterate(&closure);
5928 ret = ret && closure.success();
5929 }
5930
5931 return ret;
5932 }
5933
5934 class TearDownRegionSetsClosure : public HeapRegionClosure {
5935 private:
5936 HeapRegionSet *_old_set;
5937
5938 public:
5939 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5940
5941 bool doHeapRegion(HeapRegion* r) {
5942 if (r->is_old()) {
5943 _old_set->remove(r);
5944 } else {
5945 // We ignore free regions, we'll empty the free list afterwards.
5946 // We ignore young regions, we'll empty the young list afterwards.
5947 // We ignore humongous regions, we're not tearing down the
5948 // humongous regions set.
5949 assert(r->is_free() || r->is_young() || r->is_humongous(),
5950 "it cannot be another type");
5951 }
5952 return false;
5953 }
5954
5955 ~TearDownRegionSetsClosure() {
5956 assert(_old_set->is_empty(), "post-condition");
5957 }
5958 };
5959
5960 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5961 assert_at_safepoint(true /* should_be_vm_thread */);
5962
5963 if (!free_list_only) {
5964 TearDownRegionSetsClosure cl(&_old_set);
5965 heap_region_iterate(&cl);
5966
5967 // Note that emptying the _young_list is postponed and instead done as
5968 // the first step when rebuilding the regions sets again. The reason for
5969 // this is that during a full GC string deduplication needs to know if
5970 // a collected region was young or old when the full GC was initiated.
5971 }
5972 _hrm.remove_all_free_regions();
5973 }
5974
5975 void G1CollectedHeap::increase_used(size_t bytes) {
5976 _summary_bytes_used += bytes;
5977 }
5978
5979 void G1CollectedHeap::decrease_used(size_t bytes) {
5980 assert(_summary_bytes_used >= bytes,
5981 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5982 _summary_bytes_used, bytes);
5983 _summary_bytes_used -= bytes;
5984 }
5985
5986 void G1CollectedHeap::set_used(size_t bytes) {
5987 _summary_bytes_used = bytes;
5988 }
5989
5990 class RebuildRegionSetsClosure : public HeapRegionClosure {
5991 private:
5992 bool _free_list_only;
5993 HeapRegionSet* _old_set;
5994 HeapRegionManager* _hrm;
5995 size_t _total_used;
5996
5997 public:
5998 RebuildRegionSetsClosure(bool free_list_only,
5999 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6000 _free_list_only(free_list_only),
6001 _old_set(old_set), _hrm(hrm), _total_used(0) {
6002 assert(_hrm->num_free_regions() == 0, "pre-condition");
6003 if (!free_list_only) {
6004 assert(_old_set->is_empty(), "pre-condition");
6005 }
6006 }
6007
6008 bool doHeapRegion(HeapRegion* r) {
6009 if (r->is_empty()) {
6010 // Add free regions to the free list
6011 r->set_free();
6012 r->set_allocation_context(AllocationContext::system());
6013 _hrm->insert_into_free_list(r);
6014 } else if (!_free_list_only) {
6015 assert(!r->is_young(), "we should not come across young regions");
6016
6017 if (r->is_humongous()) {
6018 // We ignore humongous regions. We left the humongous set unchanged.
6019 } else {
6020 // Objects that were compacted would have ended up on regions
6021 // that were previously old or free. Archive regions (which are
6022 // old) will not have been touched.
6023 assert(r->is_free() || r->is_old(), "invariant");
6024 // We now consider them old, so register as such. Leave
6025 // archive regions set that way, however, while still adding
6026 // them to the old set.
6027 if (!r->is_archive()) {
6028 r->set_old();
6029 }
6030 _old_set->add(r);
6031 }
6032 _total_used += r->used();
6033 }
6034
6035 return false;
6036 }
6037
6038 size_t total_used() {
6039 return _total_used;
6040 }
6041 };
6042
6043 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6044 assert_at_safepoint(true /* should_be_vm_thread */);
6045
6046 if (!free_list_only) {
6047 _young_list->empty_list();
6048 }
6049
6050 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6051 heap_region_iterate(&cl);
6052
6053 if (!free_list_only) {
6054 set_used(cl.total_used());
6055 if (_archive_allocator != NULL) {
6056 _archive_allocator->clear_used();
6057 }
6058 }
6059 assert(used_unlocked() == recalculate_used(),
6060 "inconsistent used_unlocked(), "
6061 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6062 used_unlocked(), recalculate_used());
6063 }
6064
6065 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6066 _refine_cte_cl->set_concurrent(concurrent);
6067 }
6068
6069 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6070 HeapRegion* hr = heap_region_containing(p);
6071 return hr->is_in(p);
6072 }
6073
6074 // Methods for the mutator alloc region
6075
6076 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6077 bool force) {
6078 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6079 assert(!force || g1_policy()->can_expand_young_list(),
6080 "if force is true we should be able to expand the young list");
6081 bool young_list_full = g1_policy()->is_young_list_full();
6082 if (force || !young_list_full) {
6083 HeapRegion* new_alloc_region = new_region(word_size,
6084 false /* is_old */,
6085 false /* do_expand */);
6086 if (new_alloc_region != NULL) {
6087 set_region_short_lived_locked(new_alloc_region);
6088 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6089 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6090 return new_alloc_region;
6091 }
6092 }
6093 return NULL;
6094 }
6095
6096 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6097 size_t allocated_bytes) {
6098 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6099 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6100
6101 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6102 increase_used(allocated_bytes);
6103 _hr_printer.retire(alloc_region);
6104 // We update the eden sizes here, when the region is retired,
6105 // instead of when it's allocated, since this is the point that its
6106 // used space has been recored in _summary_bytes_used.
6107 g1mm()->update_eden_size();
6108 }
6109
6110 // Methods for the GC alloc regions
6111
6112 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6113 uint count,
6114 InCSetState dest) {
6115 assert(FreeList_lock->owned_by_self(), "pre-condition");
6116
6117 if (count < g1_policy()->max_regions(dest)) {
6118 const bool is_survivor = (dest.is_young());
6119 HeapRegion* new_alloc_region = new_region(word_size,
6120 !is_survivor,
6121 true /* do_expand */);
6122 if (new_alloc_region != NULL) {
6123 // We really only need to do this for old regions given that we
6124 // should never scan survivors. But it doesn't hurt to do it
6125 // for survivors too.
6126 new_alloc_region->record_timestamp();
6127 if (is_survivor) {
6128 new_alloc_region->set_survivor();
6129 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6130 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6131 } else {
6132 new_alloc_region->set_old();
6133 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6134 check_bitmaps("Old Region Allocation", new_alloc_region);
6135 }
6136 bool during_im = collector_state()->during_initial_mark_pause();
6137 new_alloc_region->note_start_of_copying(during_im);
6138 return new_alloc_region;
6139 }
6140 }
6141 return NULL;
6142 }
6143
6144 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6145 size_t allocated_bytes,
6146 InCSetState dest) {
6147 bool during_im = collector_state()->during_initial_mark_pause();
6148 alloc_region->note_end_of_copying(during_im);
6149 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6150 if (dest.is_young()) {
6151 young_list()->add_survivor_region(alloc_region);
6152 } else {
6153 _old_set.add(alloc_region);
6154 }
6155 _hr_printer.retire(alloc_region);
6156 }
6157
6158 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6159 bool expanded = false;
6160 uint index = _hrm.find_highest_free(&expanded);
6161
6162 if (index != G1_NO_HRM_INDEX) {
6163 if (expanded) {
6164 ergo_verbose1(ErgoHeapSizing,
6165 "attempt heap expansion",
6166 ergo_format_reason("requested address range outside heap bounds")
6167 ergo_format_byte("region size"),
6168 HeapRegion::GrainWords * HeapWordSize);
6169 }
6170 _hrm.allocate_free_regions_starting_at(index, 1);
6171 return region_at(index);
6172 }
6173 return NULL;
6174 }
6175
6176 // Heap region set verification
6177
6178 class VerifyRegionListsClosure : public HeapRegionClosure {
6179 private:
6180 HeapRegionSet* _old_set;
6181 HeapRegionSet* _humongous_set;
6182 HeapRegionManager* _hrm;
6183
6184 public:
6185 HeapRegionSetCount _old_count;
6186 HeapRegionSetCount _humongous_count;
6187 HeapRegionSetCount _free_count;
6188
6189 VerifyRegionListsClosure(HeapRegionSet* old_set,
6190 HeapRegionSet* humongous_set,
6191 HeapRegionManager* hrm) :
6192 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6193 _old_count(), _humongous_count(), _free_count(){ }
6194
6195 bool doHeapRegion(HeapRegion* hr) {
6196 if (hr->is_young()) {
6197 // TODO
6198 } else if (hr->is_humongous()) {
6199 assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
6200 _humongous_count.increment(1u, hr->capacity());
6201 } else if (hr->is_empty()) {
6202 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6203 _free_count.increment(1u, hr->capacity());
6204 } else if (hr->is_old()) {
6205 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6206 _old_count.increment(1u, hr->capacity());
6207 } else {
6208 // There are no other valid region types. Check for one invalid
6209 // one we can identify: pinned without old or humongous set.
6210 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6211 ShouldNotReachHere();
6212 }
6213 return false;
6214 }
6215
6216 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6217 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6218 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6219 old_set->total_capacity_bytes(), _old_count.capacity());
6220
6221 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6222 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6223 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6224
6225 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());
6226 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6227 free_list->total_capacity_bytes(), _free_count.capacity());
6228 }
6229 };
6230
6231 void G1CollectedHeap::verify_region_sets() {
6232 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6233
6234 // First, check the explicit lists.
6235 _hrm.verify();
6236 {
6237 // Given that a concurrent operation might be adding regions to
6238 // the secondary free list we have to take the lock before
6239 // verifying it.
6240 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6241 _secondary_free_list.verify_list();
6242 }
6243
6244 // If a concurrent region freeing operation is in progress it will
6245 // be difficult to correctly attributed any free regions we come
6246 // across to the correct free list given that they might belong to
6247 // one of several (free_list, secondary_free_list, any local lists,
6248 // etc.). So, if that's the case we will skip the rest of the
6249 // verification operation. Alternatively, waiting for the concurrent
6250 // operation to complete will have a non-trivial effect on the GC's
6251 // operation (no concurrent operation will last longer than the
6252 // interval between two calls to verification) and it might hide
6253 // any issues that we would like to catch during testing.
6254 if (free_regions_coming()) {
6255 return;
6256 }
6257
6258 // Make sure we append the secondary_free_list on the free_list so
6259 // that all free regions we will come across can be safely
6260 // attributed to the free_list.
6261 append_secondary_free_list_if_not_empty_with_lock();
6262
6263 // Finally, make sure that the region accounting in the lists is
6264 // consistent with what we see in the heap.
6265
6266 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6267 heap_region_iterate(&cl);
6268 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6269 }
6270
6271 // Optimized nmethod scanning
6272
6273 class RegisterNMethodOopClosure: public OopClosure {
6274 G1CollectedHeap* _g1h;
6275 nmethod* _nm;
6276
6277 template <class T> void do_oop_work(T* p) {
6278 T heap_oop = oopDesc::load_heap_oop(p);
6279 if (!oopDesc::is_null(heap_oop)) {
6280 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6281 HeapRegion* hr = _g1h->heap_region_containing(obj);
6282 assert(!hr->is_continues_humongous(),
6283 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6284 " starting at " HR_FORMAT,
6285 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6286
6287 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6288 hr->add_strong_code_root_locked(_nm);
6289 }
6290 }
6291
6292 public:
6293 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6294 _g1h(g1h), _nm(nm) {}
6295
6296 void do_oop(oop* p) { do_oop_work(p); }
6297 void do_oop(narrowOop* p) { do_oop_work(p); }
6298 };
6299
6300 class UnregisterNMethodOopClosure: public OopClosure {
6301 G1CollectedHeap* _g1h;
6302 nmethod* _nm;
6303
6304 template <class T> void do_oop_work(T* p) {
6305 T heap_oop = oopDesc::load_heap_oop(p);
6306 if (!oopDesc::is_null(heap_oop)) {
6307 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6308 HeapRegion* hr = _g1h->heap_region_containing(obj);
6309 assert(!hr->is_continues_humongous(),
6310 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6311 " starting at " HR_FORMAT,
6312 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6313
6314 hr->remove_strong_code_root(_nm);
6315 }
6316 }
6317
6318 public:
6319 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6320 _g1h(g1h), _nm(nm) {}
6321
6322 void do_oop(oop* p) { do_oop_work(p); }
6323 void do_oop(narrowOop* p) { do_oop_work(p); }
6324 };
6325
6326 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6327 CollectedHeap::register_nmethod(nm);
6328
6329 guarantee(nm != NULL, "sanity");
6330 RegisterNMethodOopClosure reg_cl(this, nm);
6331 nm->oops_do(®_cl);
6332 }
6333
6334 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6335 CollectedHeap::unregister_nmethod(nm);
6336
6337 guarantee(nm != NULL, "sanity");
6338 UnregisterNMethodOopClosure reg_cl(this, nm);
6339 nm->oops_do(®_cl, true);
6340 }
6341
6342 void G1CollectedHeap::purge_code_root_memory() {
6343 double purge_start = os::elapsedTime();
6344 G1CodeRootSet::purge();
6345 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6346 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6347 }
6348
6349 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6350 G1CollectedHeap* _g1h;
6351
6352 public:
6353 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6354 _g1h(g1h) {}
6355
6356 void do_code_blob(CodeBlob* cb) {
6357 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6358 if (nm == NULL) {
6359 return;
6360 }
6361
6362 if (ScavengeRootsInCode) {
6363 _g1h->register_nmethod(nm);
6364 }
6365 }
6366 };
6367
6368 void G1CollectedHeap::rebuild_strong_code_roots() {
6369 RebuildStrongCodeRootClosure blob_cl(this);
6370 CodeCache::blobs_do(&blob_cl);
6371 }