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 end of the first region in the series that
324 // should also match the end of the last region in the series.
325 HeapWord* new_end = new_obj + word_size_sum;
326 // This will be the new top of the first region that will reflect
327 // this allocation.
328 HeapWord* new_top = new_obj + word_size;
329
330 // First, we need to zero the header of the space that we will be
331 // allocating. When we update top further down, some refinement
332 // threads might try to scan the region. By zeroing the header we
333 // ensure that any thread that will try to scan the region will
334 // come across the zero klass word and bail out.
335 //
336 // NOTE: It would not have been correct to have used
337 // CollectedHeap::fill_with_object() and make the space look like
338 // an int array. The thread that is doing the allocation will
339 // later update the object header to a potentially different array
340 // type and, for a very short period of time, the klass and length
341 // fields will be inconsistent. This could cause a refinement
342 // thread to calculate the object size incorrectly.
343 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
344
345 // We will set up the first region as "starts humongous". This
346 // will also update the BOT covering all the regions to reflect
347 // that there is a single object that starts at the bottom of the
348 // first region.
349 first_hr->set_starts_humongous(new_top, new_end);
350 first_hr->set_allocation_context(context);
351 // Then, if there are any, we will set up the "continues
352 // humongous" regions.
353 HeapRegion* hr = NULL;
354 for (uint i = first + 1; i < last; ++i) {
355 hr = region_at(i);
356 hr->set_continues_humongous(first_hr);
357 hr->set_allocation_context(context);
358 }
359 // If we have "continues humongous" regions (hr != NULL), then the
360 // end of the last one should match new_end.
361 assert(hr == NULL || hr->end() == new_end, "sanity");
362
363 // Up to this point no concurrent thread would have been able to
364 // do any scanning on any region in this series. All the top
365 // fields still point to bottom, so the intersection between
366 // [bottom,top] and [card_start,card_end] will be empty. Before we
367 // update the top fields, we'll do a storestore to make sure that
368 // no thread sees the update to top before the zeroing of the
369 // object header and the BOT initialization.
370 OrderAccess::storestore();
371
372 // Now that the BOT and the object header have been initialized,
373 // we can update top of the "starts humongous" region.
374 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
375 "new_top should be in this region");
376 first_hr->set_top(new_top);
377 if (_hr_printer.is_active()) {
378 HeapWord* bottom = first_hr->bottom();
379 HeapWord* end = first_hr->orig_end();
380 if ((first + 1) == last) {
381 // the series has a single humongous region
382 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
383 } else {
384 // the series has more than one humongous regions
385 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
386 }
387 }
388
389 // Now, we will update the top fields of the "continues humongous"
390 // regions. The reason we need to do this is that, otherwise,
391 // these regions would look empty and this will confuse parts of
392 // G1. For example, the code that looks for a consecutive number
393 // of empty regions will consider them empty and try to
394 // re-allocate them. We can extend is_empty() to also include
395 // !is_continues_humongous(), but it is easier to just update the top
396 // fields here. The way we set top for all regions (i.e., top ==
397 // end for all regions but the last one, top == new_top for the
398 // last one) is actually used when we will free up the humongous
399 // region in free_humongous_region().
400 hr = NULL;
401 for (uint i = first + 1; i < last; ++i) {
402 hr = region_at(i);
403 if ((i + 1) == last) {
404 // last continues humongous region
405 assert(hr->bottom() < new_top && new_top <= hr->end(),
406 "new_top should fall on this region");
407 hr->set_top(new_top);
408 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
409 } else {
410 // not last one
411 assert(new_top > hr->end(), "new_top should be above this region");
412 hr->set_top(hr->end());
413 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
414 }
415 }
416 // If we have continues humongous regions (hr != NULL), then the
417 // end of the last one should match new_end and its top should
418 // match new_top.
419 assert(hr == NULL ||
420 (hr->end() == new_end && hr->top() == new_top), "sanity");
421 check_bitmaps("Humongous Region Allocation", first_hr);
422
423 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
424 increase_used(first_hr->used());
425 _humongous_set.add(first_hr);
426
427 return new_obj;
428 }
429
430 // If could fit into free regions w/o expansion, try.
431 // Otherwise, if can expand, do so.
432 // Otherwise, if using ex regions might help, try with ex given back.
433 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
434 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
435
436 verify_region_sets_optional();
437
438 uint first = G1_NO_HRM_INDEX;
439 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
440
441 if (obj_regions == 1) {
442 // Only one region to allocate, try to use a fast path by directly allocating
443 // from the free lists. Do not try to expand here, we will potentially do that
444 // later.
445 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
446 if (hr != NULL) {
447 first = hr->hrm_index();
448 }
449 } else {
450 // We can't allocate humongous regions spanning more than one region while
451 // cleanupComplete() is running, since some of the regions we find to be
452 // empty might not yet be added to the free list. It is not straightforward
453 // to know in which list they are on so that we can remove them. We only
454 // need to do this if we need to allocate more than one region to satisfy the
455 // current humongous allocation request. If we are only allocating one region
456 // we use the one-region region allocation code (see above), that already
457 // potentially waits for regions from the secondary free list.
458 wait_while_free_regions_coming();
459 append_secondary_free_list_if_not_empty_with_lock();
460
461 // Policy: Try only empty regions (i.e. already committed first). Maybe we
462 // are lucky enough to find some.
463 first = _hrm.find_contiguous_only_empty(obj_regions);
464 if (first != G1_NO_HRM_INDEX) {
465 _hrm.allocate_free_regions_starting_at(first, obj_regions);
466 }
467 }
468
469 if (first == G1_NO_HRM_INDEX) {
470 // Policy: We could not find enough regions for the humongous object in the
471 // free list. Look through the heap to find a mix of free and uncommitted regions.
472 // If so, try expansion.
473 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
474 if (first != G1_NO_HRM_INDEX) {
475 // We found something. Make sure these regions are committed, i.e. expand
476 // the heap. Alternatively we could do a defragmentation GC.
477 ergo_verbose1(ErgoHeapSizing,
478 "attempt heap expansion",
479 ergo_format_reason("humongous allocation request failed")
480 ergo_format_byte("allocation request"),
481 word_size * HeapWordSize);
482
483 _hrm.expand_at(first, obj_regions);
484 g1_policy()->record_new_heap_size(num_regions());
485
486 #ifdef ASSERT
487 for (uint i = first; i < first + obj_regions; ++i) {
488 HeapRegion* hr = region_at(i);
489 assert(hr->is_free(), "sanity");
490 assert(hr->is_empty(), "sanity");
491 assert(is_on_master_free_list(hr), "sanity");
492 }
493 #endif
494 _hrm.allocate_free_regions_starting_at(first, obj_regions);
495 } else {
496 // Policy: Potentially trigger a defragmentation GC.
497 }
498 }
499
500 HeapWord* result = NULL;
501 if (first != G1_NO_HRM_INDEX) {
502 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
503 word_size, context);
504 assert(result != NULL, "it should always return a valid result");
505
506 // A successful humongous object allocation changes the used space
507 // information of the old generation so we need to recalculate the
508 // sizes and update the jstat counters here.
509 g1mm()->update_sizes();
510 }
511
512 verify_region_sets_optional();
513
514 return result;
515 }
516
517 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
518 assert_heap_not_locked_and_not_at_safepoint();
519 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
520
521 uint dummy_gc_count_before;
522 uint dummy_gclocker_retry_count = 0;
523 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
524 }
525
526 HeapWord*
527 G1CollectedHeap::mem_allocate(size_t word_size,
528 bool* gc_overhead_limit_was_exceeded) {
529 assert_heap_not_locked_and_not_at_safepoint();
530
531 // Loop until the allocation is satisfied, or unsatisfied after GC.
532 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
533 uint gc_count_before;
534
535 HeapWord* result = NULL;
536 if (!is_humongous(word_size)) {
537 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
538 } else {
539 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
540 }
541 if (result != NULL) {
542 return result;
543 }
544
545 // Create the garbage collection operation...
546 VM_G1CollectForAllocation op(gc_count_before, word_size);
547 op.set_allocation_context(AllocationContext::current());
548
549 // ...and get the VM thread to execute it.
550 VMThread::execute(&op);
551
552 if (op.prologue_succeeded() && op.pause_succeeded()) {
553 // If the operation was successful we'll return the result even
554 // if it is NULL. If the allocation attempt failed immediately
555 // after a Full GC, it's unlikely we'll be able to allocate now.
556 HeapWord* result = op.result();
557 if (result != NULL && !is_humongous(word_size)) {
558 // Allocations that take place on VM operations do not do any
559 // card dirtying and we have to do it here. We only have to do
560 // this for non-humongous allocations, though.
561 dirty_young_block(result, word_size);
562 }
563 return result;
564 } else {
565 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
566 return NULL;
567 }
568 assert(op.result() == NULL,
569 "the result should be NULL if the VM op did not succeed");
570 }
571
572 // Give a warning if we seem to be looping forever.
573 if ((QueuedAllocationWarningCount > 0) &&
574 (try_count % QueuedAllocationWarningCount == 0)) {
575 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
576 }
577 }
578
579 ShouldNotReachHere();
580 return NULL;
581 }
582
583 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
584 AllocationContext_t context,
585 uint* gc_count_before_ret,
586 uint* gclocker_retry_count_ret) {
587 // Make sure you read the note in attempt_allocation_humongous().
588
589 assert_heap_not_locked_and_not_at_safepoint();
590 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
591 "be called for humongous allocation requests");
592
593 // We should only get here after the first-level allocation attempt
594 // (attempt_allocation()) failed to allocate.
595
596 // We will loop until a) we manage to successfully perform the
597 // allocation or b) we successfully schedule a collection which
598 // fails to perform the allocation. b) is the only case when we'll
599 // return NULL.
600 HeapWord* result = NULL;
601 for (int try_count = 1; /* we'll return */; try_count += 1) {
602 bool should_try_gc;
603 uint gc_count_before;
604
605 {
606 MutexLockerEx x(Heap_lock);
607 result = _allocator->attempt_allocation_locked(word_size, context);
608 if (result != NULL) {
609 return result;
610 }
611
612 if (GC_locker::is_active_and_needs_gc()) {
613 if (g1_policy()->can_expand_young_list()) {
614 // No need for an ergo verbose message here,
615 // can_expand_young_list() does this when it returns true.
616 result = _allocator->attempt_allocation_force(word_size, context);
617 if (result != NULL) {
618 return result;
619 }
620 }
621 should_try_gc = false;
622 } else {
623 // The GCLocker may not be active but the GCLocker initiated
624 // GC may not yet have been performed (GCLocker::needs_gc()
625 // returns true). In this case we do not try this GC and
626 // wait until the GCLocker initiated GC is performed, and
627 // then retry the allocation.
628 if (GC_locker::needs_gc()) {
629 should_try_gc = false;
630 } else {
631 // Read the GC count while still holding the Heap_lock.
632 gc_count_before = total_collections();
633 should_try_gc = true;
634 }
635 }
636 }
637
638 if (should_try_gc) {
639 bool succeeded;
640 result = do_collection_pause(word_size, gc_count_before, &succeeded,
641 GCCause::_g1_inc_collection_pause);
642 if (result != NULL) {
643 assert(succeeded, "only way to get back a non-NULL result");
644 return result;
645 }
646
647 if (succeeded) {
648 // If we get here we successfully scheduled a collection which
649 // failed to allocate. No point in trying to allocate
650 // further. We'll just return NULL.
651 MutexLockerEx x(Heap_lock);
652 *gc_count_before_ret = total_collections();
653 return NULL;
654 }
655 } else {
656 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
657 MutexLockerEx x(Heap_lock);
658 *gc_count_before_ret = total_collections();
659 return NULL;
660 }
661 // The GCLocker is either active or the GCLocker initiated
662 // GC has not yet been performed. Stall until it is and
663 // then retry the allocation.
664 GC_locker::stall_until_clear();
665 (*gclocker_retry_count_ret) += 1;
666 }
667
668 // We can reach here if we were unsuccessful in scheduling a
669 // collection (because another thread beat us to it) or if we were
670 // stalled due to the GC locker. In either can we should retry the
671 // allocation attempt in case another thread successfully
672 // performed a collection and reclaimed enough space. We do the
673 // first attempt (without holding the Heap_lock) here and the
674 // follow-on attempt will be at the start of the next loop
675 // iteration (after taking the Heap_lock).
676 result = _allocator->attempt_allocation(word_size, context);
677 if (result != NULL) {
678 return result;
679 }
680
681 // Give a warning if we seem to be looping forever.
682 if ((QueuedAllocationWarningCount > 0) &&
683 (try_count % QueuedAllocationWarningCount == 0)) {
684 warning("G1CollectedHeap::attempt_allocation_slow() "
685 "retries %d times", try_count);
686 }
687 }
688
689 ShouldNotReachHere();
690 return NULL;
691 }
692
693 void G1CollectedHeap::begin_archive_alloc_range() {
694 assert_at_safepoint(true /* should_be_vm_thread */);
695 if (_archive_allocator == NULL) {
696 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
697 }
698 }
699
700 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
701 // Allocations in archive regions cannot be of a size that would be considered
702 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
703 // may be different at archive-restore time.
704 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
705 }
706
707 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
708 assert_at_safepoint(true /* should_be_vm_thread */);
709 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
710 if (is_archive_alloc_too_large(word_size)) {
711 return NULL;
712 }
713 return _archive_allocator->archive_mem_allocate(word_size);
714 }
715
716 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
717 size_t end_alignment_in_bytes) {
718 assert_at_safepoint(true /* should_be_vm_thread */);
719 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
720
721 // Call complete_archive to do the real work, filling in the MemRegion
722 // array with the archive regions.
723 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
724 delete _archive_allocator;
725 _archive_allocator = NULL;
726 }
727
728 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
729 assert(ranges != NULL, "MemRegion array NULL");
730 assert(count != 0, "No MemRegions provided");
731 MemRegion reserved = _hrm.reserved();
732 for (size_t i = 0; i < count; i++) {
733 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
734 return false;
735 }
736 }
737 return true;
738 }
739
740 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
741 assert(!is_init_completed(), "Expect to be called at JVM init time");
742 assert(ranges != NULL, "MemRegion array NULL");
743 assert(count != 0, "No MemRegions provided");
744 MutexLockerEx x(Heap_lock);
745
746 MemRegion reserved = _hrm.reserved();
747 HeapWord* prev_last_addr = NULL;
748 HeapRegion* prev_last_region = NULL;
749
750 // Temporarily disable pretouching of heap pages. This interface is used
751 // when mmap'ing archived heap data in, so pre-touching is wasted.
752 FlagSetting fs(AlwaysPreTouch, false);
753
754 // Enable archive object checking in G1MarkSweep. We have to let it know
755 // about each archive range, so that objects in those ranges aren't marked.
756 G1MarkSweep::enable_archive_object_check();
757
758 // For each specified MemRegion range, allocate the corresponding G1
759 // regions and mark them as archive regions. We expect the ranges in
760 // ascending starting address order, without overlap.
761 for (size_t i = 0; i < count; i++) {
762 MemRegion curr_range = ranges[i];
763 HeapWord* start_address = curr_range.start();
764 size_t word_size = curr_range.word_size();
765 HeapWord* last_address = curr_range.last();
766 size_t commits = 0;
767
768 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
769 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
770 p2i(start_address), p2i(last_address));
771 guarantee(start_address > prev_last_addr,
772 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
773 p2i(start_address), p2i(prev_last_addr));
774 prev_last_addr = last_address;
775
776 // Check for ranges that start in the same G1 region in which the previous
777 // range ended, and adjust the start address so we don't try to allocate
778 // the same region again. If the current range is entirely within that
779 // region, skip it, just adjusting the recorded top.
780 HeapRegion* start_region = _hrm.addr_to_region(start_address);
781 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
782 start_address = start_region->end();
783 if (start_address > last_address) {
784 increase_used(word_size * HeapWordSize);
785 start_region->set_top(last_address + 1);
786 continue;
787 }
788 start_region->set_top(start_address);
789 curr_range = MemRegion(start_address, last_address + 1);
790 start_region = _hrm.addr_to_region(start_address);
791 }
792
793 // Perform the actual region allocation, exiting if it fails.
794 // Then note how much new space we have allocated.
795 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
796 return false;
797 }
798 increase_used(word_size * HeapWordSize);
799 if (commits != 0) {
800 ergo_verbose1(ErgoHeapSizing,
801 "attempt heap expansion",
802 ergo_format_reason("allocate archive regions")
803 ergo_format_byte("total size"),
804 HeapRegion::GrainWords * HeapWordSize * commits);
805 }
806
807 // Mark each G1 region touched by the range as archive, add it to the old set,
808 // and set the allocation context and top.
809 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
810 HeapRegion* last_region = _hrm.addr_to_region(last_address);
811 prev_last_region = last_region;
812
813 while (curr_region != NULL) {
814 assert(curr_region->is_empty() && !curr_region->is_pinned(),
815 "Region already in use (index %u)", curr_region->hrm_index());
816 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
817 curr_region->set_allocation_context(AllocationContext::system());
818 curr_region->set_archive();
819 _old_set.add(curr_region);
820 if (curr_region != last_region) {
821 curr_region->set_top(curr_region->end());
822 curr_region = _hrm.next_region_in_heap(curr_region);
823 } else {
824 curr_region->set_top(last_address + 1);
825 curr_region = NULL;
826 }
827 }
828
829 // Notify mark-sweep of the archive range.
830 G1MarkSweep::set_range_archive(curr_range, true);
831 }
832 return true;
833 }
834
835 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
836 assert(!is_init_completed(), "Expect to be called at JVM init time");
837 assert(ranges != NULL, "MemRegion array NULL");
838 assert(count != 0, "No MemRegions provided");
839 MemRegion reserved = _hrm.reserved();
840 HeapWord *prev_last_addr = NULL;
841 HeapRegion* prev_last_region = NULL;
842
843 // For each MemRegion, create filler objects, if needed, in the G1 regions
844 // that contain the address range. The address range actually within the
845 // MemRegion will not be modified. That is assumed to have been initialized
846 // elsewhere, probably via an mmap of archived heap data.
847 MutexLockerEx x(Heap_lock);
848 for (size_t i = 0; i < count; i++) {
849 HeapWord* start_address = ranges[i].start();
850 HeapWord* last_address = ranges[i].last();
851
852 assert(reserved.contains(start_address) && reserved.contains(last_address),
853 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
854 p2i(start_address), p2i(last_address));
855 assert(start_address > prev_last_addr,
856 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
857 p2i(start_address), p2i(prev_last_addr));
858
859 HeapRegion* start_region = _hrm.addr_to_region(start_address);
860 HeapRegion* last_region = _hrm.addr_to_region(last_address);
861 HeapWord* bottom_address = start_region->bottom();
862
863 // Check for a range beginning in the same region in which the
864 // previous one ended.
865 if (start_region == prev_last_region) {
866 bottom_address = prev_last_addr + 1;
867 }
868
869 // Verify that the regions were all marked as archive regions by
870 // alloc_archive_regions.
871 HeapRegion* curr_region = start_region;
872 while (curr_region != NULL) {
873 guarantee(curr_region->is_archive(),
874 "Expected archive region at index %u", curr_region->hrm_index());
875 if (curr_region != last_region) {
876 curr_region = _hrm.next_region_in_heap(curr_region);
877 } else {
878 curr_region = NULL;
879 }
880 }
881
882 prev_last_addr = last_address;
883 prev_last_region = last_region;
884
885 // Fill the memory below the allocated range with dummy object(s),
886 // if the region bottom does not match the range start, or if the previous
887 // range ended within the same G1 region, and there is a gap.
888 if (start_address != bottom_address) {
889 size_t fill_size = pointer_delta(start_address, bottom_address);
890 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
891 increase_used(fill_size * HeapWordSize);
892 }
893 }
894 }
895
896 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
897 uint* gc_count_before_ret,
898 uint* gclocker_retry_count_ret) {
899 assert_heap_not_locked_and_not_at_safepoint();
900 assert(!is_humongous(word_size), "attempt_allocation() should not "
901 "be called for humongous allocation requests");
902
903 AllocationContext_t context = AllocationContext::current();
904 HeapWord* result = _allocator->attempt_allocation(word_size, context);
905
906 if (result == NULL) {
907 result = attempt_allocation_slow(word_size,
908 context,
909 gc_count_before_ret,
910 gclocker_retry_count_ret);
911 }
912 assert_heap_not_locked();
913 if (result != NULL) {
914 dirty_young_block(result, word_size);
915 }
916 return result;
917 }
918
919 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
920 assert(!is_init_completed(), "Expect to be called at JVM init time");
921 assert(ranges != NULL, "MemRegion array NULL");
922 assert(count != 0, "No MemRegions provided");
923 MemRegion reserved = _hrm.reserved();
924 HeapWord* prev_last_addr = NULL;
925 HeapRegion* prev_last_region = NULL;
926 size_t size_used = 0;
927 size_t uncommitted_regions = 0;
928
929 // For each Memregion, free the G1 regions that constitute it, and
930 // notify mark-sweep that the range is no longer to be considered 'archive.'
931 MutexLockerEx x(Heap_lock);
932 for (size_t i = 0; i < count; i++) {
933 HeapWord* start_address = ranges[i].start();
934 HeapWord* last_address = ranges[i].last();
935
936 assert(reserved.contains(start_address) && reserved.contains(last_address),
937 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
938 p2i(start_address), p2i(last_address));
939 assert(start_address > prev_last_addr,
940 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
941 p2i(start_address), p2i(prev_last_addr));
942 size_used += ranges[i].byte_size();
943 prev_last_addr = last_address;
944
945 HeapRegion* start_region = _hrm.addr_to_region(start_address);
946 HeapRegion* last_region = _hrm.addr_to_region(last_address);
947
948 // Check for ranges that start in the same G1 region in which the previous
949 // range ended, and adjust the start address so we don't try to free
950 // the same region again. If the current range is entirely within that
951 // region, skip it.
952 if (start_region == prev_last_region) {
953 start_address = start_region->end();
954 if (start_address > last_address) {
955 continue;
956 }
957 start_region = _hrm.addr_to_region(start_address);
958 }
959 prev_last_region = last_region;
960
961 // After verifying that each region was marked as an archive region by
962 // alloc_archive_regions, set it free and empty and uncommit it.
963 HeapRegion* curr_region = start_region;
964 while (curr_region != NULL) {
965 guarantee(curr_region->is_archive(),
966 "Expected archive region at index %u", curr_region->hrm_index());
967 uint curr_index = curr_region->hrm_index();
968 _old_set.remove(curr_region);
969 curr_region->set_free();
970 curr_region->set_top(curr_region->bottom());
971 if (curr_region != last_region) {
972 curr_region = _hrm.next_region_in_heap(curr_region);
973 } else {
974 curr_region = NULL;
975 }
976 _hrm.shrink_at(curr_index, 1);
977 uncommitted_regions++;
978 }
979
980 // Notify mark-sweep that this is no longer an archive range.
981 G1MarkSweep::set_range_archive(ranges[i], false);
982 }
983
984 if (uncommitted_regions != 0) {
985 ergo_verbose1(ErgoHeapSizing,
986 "attempt heap shrinking",
987 ergo_format_reason("uncommitted archive regions")
988 ergo_format_byte("total size"),
989 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
990 }
991 decrease_used(size_used);
992 }
993
994 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
995 uint* gc_count_before_ret,
996 uint* gclocker_retry_count_ret) {
997 // The structure of this method has a lot of similarities to
998 // attempt_allocation_slow(). The reason these two were not merged
999 // into a single one is that such a method would require several "if
1000 // allocation is not humongous do this, otherwise do that"
1001 // conditional paths which would obscure its flow. In fact, an early
1002 // version of this code did use a unified method which was harder to
1003 // follow and, as a result, it had subtle bugs that were hard to
1004 // track down. So keeping these two methods separate allows each to
1005 // be more readable. It will be good to keep these two in sync as
1006 // much as possible.
1007
1008 assert_heap_not_locked_and_not_at_safepoint();
1009 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1010 "should only be called for humongous allocations");
1011
1012 // Humongous objects can exhaust the heap quickly, so we should check if we
1013 // need to start a marking cycle at each humongous object allocation. We do
1014 // the check before we do the actual allocation. The reason for doing it
1015 // before the allocation is that we avoid having to keep track of the newly
1016 // allocated memory while we do a GC.
1017 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1018 word_size)) {
1019 collect(GCCause::_g1_humongous_allocation);
1020 }
1021
1022 // We will loop until a) we manage to successfully perform the
1023 // allocation or b) we successfully schedule a collection which
1024 // fails to perform the allocation. b) is the only case when we'll
1025 // return NULL.
1026 HeapWord* result = NULL;
1027 for (int try_count = 1; /* we'll return */; try_count += 1) {
1028 bool should_try_gc;
1029 uint gc_count_before;
1030
1031 {
1032 MutexLockerEx x(Heap_lock);
1033
1034 // Given that humongous objects are not allocated in young
1035 // regions, we'll first try to do the allocation without doing a
1036 // collection hoping that there's enough space in the heap.
1037 result = humongous_obj_allocate(word_size, AllocationContext::current());
1038 if (result != NULL) {
1039 return result;
1040 }
1041
1042 if (GC_locker::is_active_and_needs_gc()) {
1043 should_try_gc = false;
1044 } else {
1045 // The GCLocker may not be active but the GCLocker initiated
1046 // GC may not yet have been performed (GCLocker::needs_gc()
1047 // returns true). In this case we do not try this GC and
1048 // wait until the GCLocker initiated GC is performed, and
1049 // then retry the allocation.
1050 if (GC_locker::needs_gc()) {
1051 should_try_gc = false;
1052 } else {
1053 // Read the GC count while still holding the Heap_lock.
1054 gc_count_before = total_collections();
1055 should_try_gc = true;
1056 }
1057 }
1058 }
1059
1060 if (should_try_gc) {
1061 // If we failed to allocate the humongous object, we should try to
1062 // do a collection pause (if we're allowed) in case it reclaims
1063 // enough space for the allocation to succeed after the pause.
1064
1065 bool succeeded;
1066 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1067 GCCause::_g1_humongous_allocation);
1068 if (result != NULL) {
1069 assert(succeeded, "only way to get back a non-NULL result");
1070 return result;
1071 }
1072
1073 if (succeeded) {
1074 // If we get here we successfully scheduled a collection which
1075 // failed to allocate. No point in trying to allocate
1076 // further. We'll just return NULL.
1077 MutexLockerEx x(Heap_lock);
1078 *gc_count_before_ret = total_collections();
1079 return NULL;
1080 }
1081 } else {
1082 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1083 MutexLockerEx x(Heap_lock);
1084 *gc_count_before_ret = total_collections();
1085 return NULL;
1086 }
1087 // The GCLocker is either active or the GCLocker initiated
1088 // GC has not yet been performed. Stall until it is and
1089 // then retry the allocation.
1090 GC_locker::stall_until_clear();
1091 (*gclocker_retry_count_ret) += 1;
1092 }
1093
1094 // We can reach here if we were unsuccessful in scheduling a
1095 // collection (because another thread beat us to it) or if we were
1096 // stalled due to the GC locker. In either can we should retry the
1097 // allocation attempt in case another thread successfully
1098 // performed a collection and reclaimed enough space. Give a
1099 // warning if we seem to be looping forever.
1100
1101 if ((QueuedAllocationWarningCount > 0) &&
1102 (try_count % QueuedAllocationWarningCount == 0)) {
1103 warning("G1CollectedHeap::attempt_allocation_humongous() "
1104 "retries %d times", try_count);
1105 }
1106 }
1107
1108 ShouldNotReachHere();
1109 return NULL;
1110 }
1111
1112 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1113 AllocationContext_t context,
1114 bool expect_null_mutator_alloc_region) {
1115 assert_at_safepoint(true /* should_be_vm_thread */);
1116 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1117 "the current alloc region was unexpectedly found to be non-NULL");
1118
1119 if (!is_humongous(word_size)) {
1120 return _allocator->attempt_allocation_locked(word_size, context);
1121 } else {
1122 HeapWord* result = humongous_obj_allocate(word_size, context);
1123 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1124 collector_state()->set_initiate_conc_mark_if_possible(true);
1125 }
1126 return result;
1127 }
1128
1129 ShouldNotReachHere();
1130 }
1131
1132 class PostMCRemSetClearClosure: public HeapRegionClosure {
1133 G1CollectedHeap* _g1h;
1134 ModRefBarrierSet* _mr_bs;
1135 public:
1136 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1137 _g1h(g1h), _mr_bs(mr_bs) {}
1138
1139 bool doHeapRegion(HeapRegion* r) {
1140 HeapRegionRemSet* hrrs = r->rem_set();
1141
1142 if (r->is_continues_humongous()) {
1143 // We'll assert that the strong code root list and RSet is empty
1144 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1145 assert(hrrs->occupied() == 0, "RSet should be empty");
1146 return false;
1147 }
1148
1149 _g1h->reset_gc_time_stamps(r);
1150 hrrs->clear();
1151 // You might think here that we could clear just the cards
1152 // corresponding to the used region. But no: if we leave a dirty card
1153 // in a region we might allocate into, then it would prevent that card
1154 // from being enqueued, and cause it to be missed.
1155 // Re: the performance cost: we shouldn't be doing full GC anyway!
1156 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1157
1158 return false;
1159 }
1160 };
1161
1162 void G1CollectedHeap::clear_rsets_post_compaction() {
1163 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1164 heap_region_iterate(&rs_clear);
1165 }
1166
1167 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1168 G1CollectedHeap* _g1h;
1169 UpdateRSOopClosure _cl;
1170 public:
1171 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1172 _cl(g1->g1_rem_set(), worker_i),
1173 _g1h(g1)
1174 { }
1175
1176 bool doHeapRegion(HeapRegion* r) {
1177 if (!r->is_continues_humongous()) {
1178 _cl.set_from(r);
1179 r->oop_iterate(&_cl);
1180 }
1181 return false;
1182 }
1183 };
1184
1185 class ParRebuildRSTask: public AbstractGangTask {
1186 G1CollectedHeap* _g1;
1187 HeapRegionClaimer _hrclaimer;
1188
1189 public:
1190 ParRebuildRSTask(G1CollectedHeap* g1) :
1191 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1192
1193 void work(uint worker_id) {
1194 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1195 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1196 }
1197 };
1198
1199 class PostCompactionPrinterClosure: public HeapRegionClosure {
1200 private:
1201 G1HRPrinter* _hr_printer;
1202 public:
1203 bool doHeapRegion(HeapRegion* hr) {
1204 assert(!hr->is_young(), "not expecting to find young regions");
1205 if (hr->is_free()) {
1206 // We only generate output for non-empty regions.
1207 } else if (hr->is_starts_humongous()) {
1208 if (hr->region_num() == 1) {
1209 // single humongous region
1210 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1211 } else {
1212 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1213 }
1214 } else if (hr->is_continues_humongous()) {
1215 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1216 } else if (hr->is_archive()) {
1217 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1218 } else if (hr->is_old()) {
1219 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1220 } else {
1221 ShouldNotReachHere();
1222 }
1223 return false;
1224 }
1225
1226 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1227 : _hr_printer(hr_printer) { }
1228 };
1229
1230 void G1CollectedHeap::print_hrm_post_compaction() {
1231 PostCompactionPrinterClosure cl(hr_printer());
1232 heap_region_iterate(&cl);
1233 }
1234
1235 bool G1CollectedHeap::do_collection(bool explicit_gc,
1236 bool clear_all_soft_refs,
1237 size_t word_size) {
1238 assert_at_safepoint(true /* should_be_vm_thread */);
1239
1240 if (GC_locker::check_active_before_gc()) {
1241 return false;
1242 }
1243
1244 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1245 gc_timer->register_gc_start();
1246
1247 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1248 GCIdMark gc_id_mark;
1249 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1250
1251 SvcGCMarker sgcm(SvcGCMarker::FULL);
1252 ResourceMark rm;
1253
1254 G1Log::update_level();
1255 print_heap_before_gc();
1256 trace_heap_before_gc(gc_tracer);
1257
1258 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1259
1260 verify_region_sets_optional();
1261
1262 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1263 collector_policy()->should_clear_all_soft_refs();
1264
1265 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1266
1267 {
1268 IsGCActiveMark x;
1269
1270 // Timing
1271 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1272 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1273
1274 {
1275 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1276 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1277 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1278
1279 g1_policy()->record_full_collection_start();
1280
1281 // Note: When we have a more flexible GC logging framework that
1282 // allows us to add optional attributes to a GC log record we
1283 // could consider timing and reporting how long we wait in the
1284 // following two methods.
1285 wait_while_free_regions_coming();
1286 // If we start the compaction before the CM threads finish
1287 // scanning the root regions we might trip them over as we'll
1288 // be moving objects / updating references. So let's wait until
1289 // they are done. By telling them to abort, they should complete
1290 // early.
1291 _cm->root_regions()->abort();
1292 _cm->root_regions()->wait_until_scan_finished();
1293 append_secondary_free_list_if_not_empty_with_lock();
1294
1295 gc_prologue(true);
1296 increment_total_collections(true /* full gc */);
1297 increment_old_marking_cycles_started();
1298
1299 assert(used() == recalculate_used(), "Should be equal");
1300
1301 verify_before_gc();
1302
1303 check_bitmaps("Full GC Start");
1304 pre_full_gc_dump(gc_timer);
1305
1306 #if defined(COMPILER2) || INCLUDE_JVMCI
1307 DerivedPointerTable::clear();
1308 #endif
1309
1310 // Disable discovery and empty the discovered lists
1311 // for the CM ref processor.
1312 ref_processor_cm()->disable_discovery();
1313 ref_processor_cm()->abandon_partial_discovery();
1314 ref_processor_cm()->verify_no_references_recorded();
1315
1316 // Abandon current iterations of concurrent marking and concurrent
1317 // refinement, if any are in progress. We have to do this before
1318 // wait_until_scan_finished() below.
1319 concurrent_mark()->abort();
1320
1321 // Make sure we'll choose a new allocation region afterwards.
1322 _allocator->release_mutator_alloc_region();
1323 _allocator->abandon_gc_alloc_regions();
1324 g1_rem_set()->cleanupHRRS();
1325
1326 // We should call this after we retire any currently active alloc
1327 // regions so that all the ALLOC / RETIRE events are generated
1328 // before the start GC event.
1329 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1330
1331 // We may have added regions to the current incremental collection
1332 // set between the last GC or pause and now. We need to clear the
1333 // incremental collection set and then start rebuilding it afresh
1334 // after this full GC.
1335 abandon_collection_set(g1_policy()->inc_cset_head());
1336 g1_policy()->clear_incremental_cset();
1337 g1_policy()->stop_incremental_cset_building();
1338
1339 tear_down_region_sets(false /* free_list_only */);
1340 collector_state()->set_gcs_are_young(true);
1341
1342 // See the comments in g1CollectedHeap.hpp and
1343 // G1CollectedHeap::ref_processing_init() about
1344 // how reference processing currently works in G1.
1345
1346 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1347 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1348
1349 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1350 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1351
1352 ref_processor_stw()->enable_discovery();
1353 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1354
1355 // Do collection work
1356 {
1357 HandleMark hm; // Discard invalid handles created during gc
1358 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1359 }
1360
1361 assert(num_free_regions() == 0, "we should not have added any free regions");
1362 rebuild_region_sets(false /* free_list_only */);
1363
1364 // Enqueue any discovered reference objects that have
1365 // not been removed from the discovered lists.
1366 ref_processor_stw()->enqueue_discovered_references();
1367
1368 #if defined(COMPILER2) || INCLUDE_JVMCI
1369 DerivedPointerTable::update_pointers();
1370 #endif
1371
1372 MemoryService::track_memory_usage();
1373
1374 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1375 ref_processor_stw()->verify_no_references_recorded();
1376
1377 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1378 ClassLoaderDataGraph::purge();
1379 MetaspaceAux::verify_metrics();
1380
1381 // Note: since we've just done a full GC, concurrent
1382 // marking is no longer active. Therefore we need not
1383 // re-enable reference discovery for the CM ref processor.
1384 // That will be done at the start of the next marking cycle.
1385 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1386 ref_processor_cm()->verify_no_references_recorded();
1387
1388 reset_gc_time_stamp();
1389 // Since everything potentially moved, we will clear all remembered
1390 // sets, and clear all cards. Later we will rebuild remembered
1391 // sets. We will also reset the GC time stamps of the regions.
1392 clear_rsets_post_compaction();
1393 check_gc_time_stamps();
1394
1395 // Resize the heap if necessary.
1396 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1397
1398 if (_hr_printer.is_active()) {
1399 // We should do this after we potentially resize the heap so
1400 // that all the COMMIT / UNCOMMIT events are generated before
1401 // the end GC event.
1402
1403 print_hrm_post_compaction();
1404 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1405 }
1406
1407 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1408 if (hot_card_cache->use_cache()) {
1409 hot_card_cache->reset_card_counts();
1410 hot_card_cache->reset_hot_cache();
1411 }
1412
1413 // Rebuild remembered sets of all regions.
1414 uint n_workers =
1415 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1416 workers()->active_workers(),
1417 Threads::number_of_non_daemon_threads());
1418 workers()->set_active_workers(n_workers);
1419
1420 ParRebuildRSTask rebuild_rs_task(this);
1421 workers()->run_task(&rebuild_rs_task);
1422
1423 // Rebuild the strong code root lists for each region
1424 rebuild_strong_code_roots();
1425
1426 if (true) { // FIXME
1427 MetaspaceGC::compute_new_size();
1428 }
1429
1430 #ifdef TRACESPINNING
1431 ParallelTaskTerminator::print_termination_counts();
1432 #endif
1433
1434 // Discard all rset updates
1435 JavaThread::dirty_card_queue_set().abandon_logs();
1436 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1437
1438 _young_list->reset_sampled_info();
1439 // At this point there should be no regions in the
1440 // entire heap tagged as young.
1441 assert(check_young_list_empty(true /* check_heap */),
1442 "young list should be empty at this point");
1443
1444 // Update the number of full collections that have been completed.
1445 increment_old_marking_cycles_completed(false /* concurrent */);
1446
1447 _hrm.verify_optional();
1448 verify_region_sets_optional();
1449
1450 verify_after_gc();
1451
1452 // Clear the previous marking bitmap, if needed for bitmap verification.
1453 // Note we cannot do this when we clear the next marking bitmap in
1454 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1455 // objects marked during a full GC against the previous bitmap.
1456 // But we need to clear it before calling check_bitmaps below since
1457 // the full GC has compacted objects and updated TAMS but not updated
1458 // the prev bitmap.
1459 if (G1VerifyBitmaps) {
1460 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1461 }
1462 check_bitmaps("Full GC End");
1463
1464 // Start a new incremental collection set for the next pause
1465 assert(g1_policy()->collection_set() == NULL, "must be");
1466 g1_policy()->start_incremental_cset_building();
1467
1468 clear_cset_fast_test();
1469
1470 _allocator->init_mutator_alloc_region();
1471
1472 g1_policy()->record_full_collection_end();
1473
1474 if (G1Log::fine()) {
1475 g1_policy()->print_heap_transition();
1476 }
1477
1478 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1479 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1480 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1481 // before any GC notifications are raised.
1482 g1mm()->update_sizes();
1483
1484 gc_epilogue(true);
1485 }
1486
1487 if (G1Log::finer()) {
1488 g1_policy()->print_detailed_heap_transition(true /* full */);
1489 }
1490
1491 print_heap_after_gc();
1492 trace_heap_after_gc(gc_tracer);
1493
1494 post_full_gc_dump(gc_timer);
1495
1496 gc_timer->register_gc_end();
1497 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1498 }
1499
1500 return true;
1501 }
1502
1503 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1504 // do_collection() will return whether it succeeded in performing
1505 // the GC. Currently, there is no facility on the
1506 // do_full_collection() API to notify the caller than the collection
1507 // did not succeed (e.g., because it was locked out by the GC
1508 // locker). So, right now, we'll ignore the return value.
1509 bool dummy = do_collection(true, /* explicit_gc */
1510 clear_all_soft_refs,
1511 0 /* word_size */);
1512 }
1513
1514 // This code is mostly copied from TenuredGeneration.
1515 void
1516 G1CollectedHeap::
1517 resize_if_necessary_after_full_collection(size_t word_size) {
1518 // Include the current allocation, if any, and bytes that will be
1519 // pre-allocated to support collections, as "used".
1520 const size_t used_after_gc = used();
1521 const size_t capacity_after_gc = capacity();
1522 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1523
1524 // This is enforced in arguments.cpp.
1525 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1526 "otherwise the code below doesn't make sense");
1527
1528 // We don't have floating point command-line arguments
1529 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1530 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1531 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1532 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1533
1534 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1535 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1536
1537 // We have to be careful here as these two calculations can overflow
1538 // 32-bit size_t's.
1539 double used_after_gc_d = (double) used_after_gc;
1540 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1541 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1542
1543 // Let's make sure that they are both under the max heap size, which
1544 // by default will make them fit into a size_t.
1545 double desired_capacity_upper_bound = (double) max_heap_size;
1546 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1547 desired_capacity_upper_bound);
1548 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1549 desired_capacity_upper_bound);
1550
1551 // We can now safely turn them into size_t's.
1552 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1553 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1554
1555 // This assert only makes sense here, before we adjust them
1556 // with respect to the min and max heap size.
1557 assert(minimum_desired_capacity <= maximum_desired_capacity,
1558 "minimum_desired_capacity = " SIZE_FORMAT ", "
1559 "maximum_desired_capacity = " SIZE_FORMAT,
1560 minimum_desired_capacity, maximum_desired_capacity);
1561
1562 // Should not be greater than the heap max size. No need to adjust
1563 // it with respect to the heap min size as it's a lower bound (i.e.,
1564 // we'll try to make the capacity larger than it, not smaller).
1565 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1566 // Should not be less than the heap min size. No need to adjust it
1567 // with respect to the heap max size as it's an upper bound (i.e.,
1568 // we'll try to make the capacity smaller than it, not greater).
1569 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1570
1571 if (capacity_after_gc < minimum_desired_capacity) {
1572 // Don't expand unless it's significant
1573 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1574 ergo_verbose4(ErgoHeapSizing,
1575 "attempt heap expansion",
1576 ergo_format_reason("capacity lower than "
1577 "min desired capacity after Full GC")
1578 ergo_format_byte("capacity")
1579 ergo_format_byte("occupancy")
1580 ergo_format_byte_perc("min desired capacity"),
1581 capacity_after_gc, used_after_gc,
1582 minimum_desired_capacity, (double) MinHeapFreeRatio);
1583 expand(expand_bytes);
1584
1585 // No expansion, now see if we want to shrink
1586 } else if (capacity_after_gc > maximum_desired_capacity) {
1587 // Capacity too large, compute shrinking size
1588 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1589 ergo_verbose4(ErgoHeapSizing,
1590 "attempt heap shrinking",
1591 ergo_format_reason("capacity higher than "
1592 "max desired capacity after Full GC")
1593 ergo_format_byte("capacity")
1594 ergo_format_byte("occupancy")
1595 ergo_format_byte_perc("max desired capacity"),
1596 capacity_after_gc, used_after_gc,
1597 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1598 shrink(shrink_bytes);
1599 }
1600 }
1601
1602 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1603 AllocationContext_t context,
1604 bool do_gc,
1605 bool clear_all_soft_refs,
1606 bool expect_null_mutator_alloc_region,
1607 bool* gc_succeeded) {
1608 *gc_succeeded = true;
1609 // Let's attempt the allocation first.
1610 HeapWord* result =
1611 attempt_allocation_at_safepoint(word_size,
1612 context,
1613 expect_null_mutator_alloc_region);
1614 if (result != NULL) {
1615 assert(*gc_succeeded, "sanity");
1616 return result;
1617 }
1618
1619 // In a G1 heap, we're supposed to keep allocation from failing by
1620 // incremental pauses. Therefore, at least for now, we'll favor
1621 // expansion over collection. (This might change in the future if we can
1622 // do something smarter than full collection to satisfy a failed alloc.)
1623 result = expand_and_allocate(word_size, context);
1624 if (result != NULL) {
1625 assert(*gc_succeeded, "sanity");
1626 return result;
1627 }
1628
1629 if (do_gc) {
1630 // Expansion didn't work, we'll try to do a Full GC.
1631 *gc_succeeded = do_collection(false, /* explicit_gc */
1632 clear_all_soft_refs,
1633 word_size);
1634 }
1635
1636 return NULL;
1637 }
1638
1639 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1640 AllocationContext_t context,
1641 bool* succeeded) {
1642 assert_at_safepoint(true /* should_be_vm_thread */);
1643
1644 // Attempts to allocate followed by Full GC.
1645 HeapWord* result =
1646 satisfy_failed_allocation_helper(word_size,
1647 context,
1648 true, /* do_gc */
1649 false, /* clear_all_soft_refs */
1650 false, /* expect_null_mutator_alloc_region */
1651 succeeded);
1652
1653 if (result != NULL || !*succeeded) {
1654 return result;
1655 }
1656
1657 // Attempts to allocate followed by Full GC that will collect all soft references.
1658 result = satisfy_failed_allocation_helper(word_size,
1659 context,
1660 true, /* do_gc */
1661 true, /* clear_all_soft_refs */
1662 true, /* expect_null_mutator_alloc_region */
1663 succeeded);
1664
1665 if (result != NULL || !*succeeded) {
1666 return result;
1667 }
1668
1669 // Attempts to allocate, no GC
1670 result = satisfy_failed_allocation_helper(word_size,
1671 context,
1672 false, /* do_gc */
1673 false, /* clear_all_soft_refs */
1674 true, /* expect_null_mutator_alloc_region */
1675 succeeded);
1676
1677 if (result != NULL) {
1678 assert(*succeeded, "sanity");
1679 return result;
1680 }
1681
1682 assert(!collector_policy()->should_clear_all_soft_refs(),
1683 "Flag should have been handled and cleared prior to this point");
1684
1685 // What else? We might try synchronous finalization later. If the total
1686 // space available is large enough for the allocation, then a more
1687 // complete compaction phase than we've tried so far might be
1688 // appropriate.
1689 assert(*succeeded, "sanity");
1690 return NULL;
1691 }
1692
1693 // Attempting to expand the heap sufficiently
1694 // to support an allocation of the given "word_size". If
1695 // successful, perform the allocation and return the address of the
1696 // allocated block, or else "NULL".
1697
1698 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1699 assert_at_safepoint(true /* should_be_vm_thread */);
1700
1701 verify_region_sets_optional();
1702
1703 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1704 ergo_verbose1(ErgoHeapSizing,
1705 "attempt heap expansion",
1706 ergo_format_reason("allocation request failed")
1707 ergo_format_byte("allocation request"),
1708 word_size * HeapWordSize);
1709 if (expand(expand_bytes)) {
1710 _hrm.verify_optional();
1711 verify_region_sets_optional();
1712 return attempt_allocation_at_safepoint(word_size,
1713 context,
1714 false /* expect_null_mutator_alloc_region */);
1715 }
1716 return NULL;
1717 }
1718
1719 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1720 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1721 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1722 HeapRegion::GrainBytes);
1723 ergo_verbose2(ErgoHeapSizing,
1724 "expand the heap",
1725 ergo_format_byte("requested expansion amount")
1726 ergo_format_byte("attempted expansion amount"),
1727 expand_bytes, aligned_expand_bytes);
1728
1729 if (is_maximal_no_gc()) {
1730 ergo_verbose0(ErgoHeapSizing,
1731 "did not expand the heap",
1732 ergo_format_reason("heap already fully expanded"));
1733 return false;
1734 }
1735
1736 double expand_heap_start_time_sec = os::elapsedTime();
1737 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1738 assert(regions_to_expand > 0, "Must expand by at least one region");
1739
1740 uint expanded_by = _hrm.expand_by(regions_to_expand);
1741 if (expand_time_ms != NULL) {
1742 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1743 }
1744
1745 if (expanded_by > 0) {
1746 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1747 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1748 g1_policy()->record_new_heap_size(num_regions());
1749 } else {
1750 ergo_verbose0(ErgoHeapSizing,
1751 "did not expand the heap",
1752 ergo_format_reason("heap expansion operation failed"));
1753 // The expansion of the virtual storage space was unsuccessful.
1754 // Let's see if it was because we ran out of swap.
1755 if (G1ExitOnExpansionFailure &&
1756 _hrm.available() >= regions_to_expand) {
1757 // We had head room...
1758 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1759 }
1760 }
1761 return regions_to_expand > 0;
1762 }
1763
1764 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1765 size_t aligned_shrink_bytes =
1766 ReservedSpace::page_align_size_down(shrink_bytes);
1767 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1768 HeapRegion::GrainBytes);
1769 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1770
1771 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1772 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1773
1774 ergo_verbose3(ErgoHeapSizing,
1775 "shrink the heap",
1776 ergo_format_byte("requested shrinking amount")
1777 ergo_format_byte("aligned shrinking amount")
1778 ergo_format_byte("attempted shrinking amount"),
1779 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1780 if (num_regions_removed > 0) {
1781 g1_policy()->record_new_heap_size(num_regions());
1782 } else {
1783 ergo_verbose0(ErgoHeapSizing,
1784 "did not shrink the heap",
1785 ergo_format_reason("heap shrinking operation failed"));
1786 }
1787 }
1788
1789 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1790 verify_region_sets_optional();
1791
1792 // We should only reach here at the end of a Full GC which means we
1793 // should not not be holding to any GC alloc regions. The method
1794 // below will make sure of that and do any remaining clean up.
1795 _allocator->abandon_gc_alloc_regions();
1796
1797 // Instead of tearing down / rebuilding the free lists here, we
1798 // could instead use the remove_all_pending() method on free_list to
1799 // remove only the ones that we need to remove.
1800 tear_down_region_sets(true /* free_list_only */);
1801 shrink_helper(shrink_bytes);
1802 rebuild_region_sets(true /* free_list_only */);
1803
1804 _hrm.verify_optional();
1805 verify_region_sets_optional();
1806 }
1807
1808 // Public methods.
1809
1810 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1811 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1812 #endif // _MSC_VER
1813
1814
1815 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1816 CollectedHeap(),
1817 _g1_policy(policy_),
1818 _dirty_card_queue_set(false),
1819 _into_cset_dirty_card_queue_set(false),
1820 _is_alive_closure_cm(this),
1821 _is_alive_closure_stw(this),
1822 _ref_processor_cm(NULL),
1823 _ref_processor_stw(NULL),
1824 _bot_shared(NULL),
1825 _cg1r(NULL),
1826 _g1mm(NULL),
1827 _refine_cte_cl(NULL),
1828 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1829 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1830 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1831 _humongous_reclaim_candidates(),
1832 _has_humongous_reclaim_candidates(false),
1833 _archive_allocator(NULL),
1834 _free_regions_coming(false),
1835 _young_list(new YoungList(this)),
1836 _gc_time_stamp(0),
1837 _summary_bytes_used(0),
1838 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1839 _old_evac_stats(OldPLABSize, PLABWeight),
1840 _expand_heap_after_alloc_failure(true),
1841 _old_marking_cycles_started(0),
1842 _old_marking_cycles_completed(0),
1843 _heap_summary_sent(false),
1844 _in_cset_fast_test(),
1845 _dirty_cards_region_list(NULL),
1846 _worker_cset_start_region(NULL),
1847 _worker_cset_start_region_time_stamp(NULL),
1848 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1849 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1850 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1851 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1852
1853 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1854 /* are_GC_task_threads */true,
1855 /* are_ConcurrentGC_threads */false);
1856 _workers->initialize_workers();
1857
1858 _allocator = G1Allocator::create_allocator(this);
1859 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1860
1861 // Override the default _filler_array_max_size so that no humongous filler
1862 // objects are created.
1863 _filler_array_max_size = _humongous_object_threshold_in_words;
1864
1865 uint n_queues = ParallelGCThreads;
1866 _task_queues = new RefToScanQueueSet(n_queues);
1867
1868 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1869 assert(n_rem_sets > 0, "Invariant.");
1870
1871 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1872 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1873 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1874
1875 for (uint i = 0; i < n_queues; i++) {
1876 RefToScanQueue* q = new RefToScanQueue();
1877 q->initialize();
1878 _task_queues->register_queue(i, q);
1879 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1880 }
1881 clear_cset_start_regions();
1882
1883 // Initialize the G1EvacuationFailureALot counters and flags.
1884 NOT_PRODUCT(reset_evacuation_should_fail();)
1885
1886 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1887 }
1888
1889 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1890 size_t size,
1891 size_t translation_factor) {
1892 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1893 // Allocate a new reserved space, preferring to use large pages.
1894 ReservedSpace rs(size, preferred_page_size);
1895 G1RegionToSpaceMapper* result =
1896 G1RegionToSpaceMapper::create_mapper(rs,
1897 size,
1898 rs.alignment(),
1899 HeapRegion::GrainBytes,
1900 translation_factor,
1901 mtGC);
1902 if (TracePageSizes) {
1903 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1904 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1905 }
1906 return result;
1907 }
1908
1909 jint G1CollectedHeap::initialize() {
1910 CollectedHeap::pre_initialize();
1911 os::enable_vtime();
1912
1913 G1Log::init();
1914
1915 // Necessary to satisfy locking discipline assertions.
1916
1917 MutexLocker x(Heap_lock);
1918
1919 // We have to initialize the printer before committing the heap, as
1920 // it will be used then.
1921 _hr_printer.set_active(G1PrintHeapRegions);
1922
1923 // While there are no constraints in the GC code that HeapWordSize
1924 // be any particular value, there are multiple other areas in the
1925 // system which believe this to be true (e.g. oop->object_size in some
1926 // cases incorrectly returns the size in wordSize units rather than
1927 // HeapWordSize).
1928 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1929
1930 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1931 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1932 size_t heap_alignment = collector_policy()->heap_alignment();
1933
1934 // Ensure that the sizes are properly aligned.
1935 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1936 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1937 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1938
1939 _refine_cte_cl = new RefineCardTableEntryClosure();
1940
1941 jint ecode = JNI_OK;
1942 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1943 if (_cg1r == NULL) {
1944 return ecode;
1945 }
1946
1947 // Reserve the maximum.
1948
1949 // When compressed oops are enabled, the preferred heap base
1950 // is calculated by subtracting the requested size from the
1951 // 32Gb boundary and using the result as the base address for
1952 // heap reservation. If the requested size is not aligned to
1953 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1954 // into the ReservedHeapSpace constructor) then the actual
1955 // base of the reserved heap may end up differing from the
1956 // address that was requested (i.e. the preferred heap base).
1957 // If this happens then we could end up using a non-optimal
1958 // compressed oops mode.
1959
1960 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1961 heap_alignment);
1962
1963 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1964
1965 // Create the barrier set for the entire reserved region.
1966 G1SATBCardTableLoggingModRefBS* bs
1967 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1968 bs->initialize();
1969 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1970 set_barrier_set(bs);
1971
1972 // Also create a G1 rem set.
1973 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1974
1975 // Carve out the G1 part of the heap.
1976
1977 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1978 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1979 G1RegionToSpaceMapper* heap_storage =
1980 G1RegionToSpaceMapper::create_mapper(g1_rs,
1981 g1_rs.size(),
1982 page_size,
1983 HeapRegion::GrainBytes,
1984 1,
1985 mtJavaHeap);
1986 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1987 max_byte_size, page_size,
1988 heap_rs.base(),
1989 heap_rs.size());
1990 heap_storage->set_mapping_changed_listener(&_listener);
1991
1992 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1993 G1RegionToSpaceMapper* bot_storage =
1994 create_aux_memory_mapper("Block offset table",
1995 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1996 G1BlockOffsetSharedArray::heap_map_factor());
1997
1998 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1999 G1RegionToSpaceMapper* cardtable_storage =
2000 create_aux_memory_mapper("Card table",
2001 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2002 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2003
2004 G1RegionToSpaceMapper* card_counts_storage =
2005 create_aux_memory_mapper("Card counts table",
2006 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2007 G1CardCounts::heap_map_factor());
2008
2009 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2010 G1RegionToSpaceMapper* prev_bitmap_storage =
2011 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2012 G1RegionToSpaceMapper* next_bitmap_storage =
2013 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2014
2015 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2016 g1_barrier_set()->initialize(cardtable_storage);
2017 // Do later initialization work for concurrent refinement.
2018 _cg1r->init(card_counts_storage);
2019
2020 // 6843694 - ensure that the maximum region index can fit
2021 // in the remembered set structures.
2022 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2023 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2024
2025 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2026 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2027 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2028 "too many cards per region");
2029
2030 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2031
2032 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2033
2034 {
2035 HeapWord* start = _hrm.reserved().start();
2036 HeapWord* end = _hrm.reserved().end();
2037 size_t granularity = HeapRegion::GrainBytes;
2038
2039 _in_cset_fast_test.initialize(start, end, granularity);
2040 _humongous_reclaim_candidates.initialize(start, end, granularity);
2041 }
2042
2043 // Create the ConcurrentMark data structure and thread.
2044 // (Must do this late, so that "max_regions" is defined.)
2045 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2046 if (_cm == NULL || !_cm->completed_initialization()) {
2047 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2048 return JNI_ENOMEM;
2049 }
2050 _cmThread = _cm->cmThread();
2051
2052 // Initialize the from_card cache structure of HeapRegionRemSet.
2053 HeapRegionRemSet::init_heap(max_regions());
2054
2055 // Now expand into the initial heap size.
2056 if (!expand(init_byte_size)) {
2057 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2058 return JNI_ENOMEM;
2059 }
2060
2061 // Perform any initialization actions delegated to the policy.
2062 g1_policy()->init();
2063
2064 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2065 SATB_Q_FL_lock,
2066 G1SATBProcessCompletedThreshold,
2067 Shared_SATB_Q_lock);
2068
2069 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2070 DirtyCardQ_CBL_mon,
2071 DirtyCardQ_FL_lock,
2072 concurrent_g1_refine()->yellow_zone(),
2073 concurrent_g1_refine()->red_zone(),
2074 Shared_DirtyCardQ_lock);
2075
2076 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2077 DirtyCardQ_CBL_mon,
2078 DirtyCardQ_FL_lock,
2079 -1, // never trigger processing
2080 -1, // no limit on length
2081 Shared_DirtyCardQ_lock,
2082 &JavaThread::dirty_card_queue_set());
2083
2084 // Initialize the card queue set used to hold cards containing
2085 // references into the collection set.
2086 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2087 DirtyCardQ_CBL_mon,
2088 DirtyCardQ_FL_lock,
2089 -1, // never trigger processing
2090 -1, // no limit on length
2091 Shared_DirtyCardQ_lock,
2092 &JavaThread::dirty_card_queue_set());
2093
2094 // Here we allocate the dummy HeapRegion that is required by the
2095 // G1AllocRegion class.
2096 HeapRegion* dummy_region = _hrm.get_dummy_region();
2097
2098 // We'll re-use the same region whether the alloc region will
2099 // require BOT updates or not and, if it doesn't, then a non-young
2100 // region will complain that it cannot support allocations without
2101 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2102 dummy_region->set_eden();
2103 // Make sure it's full.
2104 dummy_region->set_top(dummy_region->end());
2105 G1AllocRegion::setup(this, dummy_region);
2106
2107 _allocator->init_mutator_alloc_region();
2108
2109 // Do create of the monitoring and management support so that
2110 // values in the heap have been properly initialized.
2111 _g1mm = new G1MonitoringSupport(this);
2112
2113 G1StringDedup::initialize();
2114
2115 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2116 for (uint i = 0; i < ParallelGCThreads; i++) {
2117 new (&_preserved_objs[i]) OopAndMarkOopStack();
2118 }
2119
2120 return JNI_OK;
2121 }
2122
2123 void G1CollectedHeap::stop() {
2124 // Stop all concurrent threads. We do this to make sure these threads
2125 // do not continue to execute and access resources (e.g. gclog_or_tty)
2126 // that are destroyed during shutdown.
2127 _cg1r->stop();
2128 _cmThread->stop();
2129 if (G1StringDedup::is_enabled()) {
2130 G1StringDedup::stop();
2131 }
2132 }
2133
2134 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2135 return HeapRegion::max_region_size();
2136 }
2137
2138 void G1CollectedHeap::post_initialize() {
2139 CollectedHeap::post_initialize();
2140 ref_processing_init();
2141 }
2142
2143 void G1CollectedHeap::ref_processing_init() {
2144 // Reference processing in G1 currently works as follows:
2145 //
2146 // * There are two reference processor instances. One is
2147 // used to record and process discovered references
2148 // during concurrent marking; the other is used to
2149 // record and process references during STW pauses
2150 // (both full and incremental).
2151 // * Both ref processors need to 'span' the entire heap as
2152 // the regions in the collection set may be dotted around.
2153 //
2154 // * For the concurrent marking ref processor:
2155 // * Reference discovery is enabled at initial marking.
2156 // * Reference discovery is disabled and the discovered
2157 // references processed etc during remarking.
2158 // * Reference discovery is MT (see below).
2159 // * Reference discovery requires a barrier (see below).
2160 // * Reference processing may or may not be MT
2161 // (depending on the value of ParallelRefProcEnabled
2162 // and ParallelGCThreads).
2163 // * A full GC disables reference discovery by the CM
2164 // ref processor and abandons any entries on it's
2165 // discovered lists.
2166 //
2167 // * For the STW processor:
2168 // * Non MT discovery is enabled at the start of a full GC.
2169 // * Processing and enqueueing during a full GC is non-MT.
2170 // * During a full GC, references are processed after marking.
2171 //
2172 // * Discovery (may or may not be MT) is enabled at the start
2173 // of an incremental evacuation pause.
2174 // * References are processed near the end of a STW evacuation pause.
2175 // * For both types of GC:
2176 // * Discovery is atomic - i.e. not concurrent.
2177 // * Reference discovery will not need a barrier.
2178
2179 MemRegion mr = reserved_region();
2180
2181 // Concurrent Mark ref processor
2182 _ref_processor_cm =
2183 new ReferenceProcessor(mr, // span
2184 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2185 // mt processing
2186 ParallelGCThreads,
2187 // degree of mt processing
2188 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2189 // mt discovery
2190 MAX2(ParallelGCThreads, ConcGCThreads),
2191 // degree of mt discovery
2192 false,
2193 // Reference discovery is not atomic
2194 &_is_alive_closure_cm);
2195 // is alive closure
2196 // (for efficiency/performance)
2197
2198 // STW ref processor
2199 _ref_processor_stw =
2200 new ReferenceProcessor(mr, // span
2201 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2202 // mt processing
2203 ParallelGCThreads,
2204 // degree of mt processing
2205 (ParallelGCThreads > 1),
2206 // mt discovery
2207 ParallelGCThreads,
2208 // degree of mt discovery
2209 true,
2210 // Reference discovery is atomic
2211 &_is_alive_closure_stw);
2212 // is alive closure
2213 // (for efficiency/performance)
2214 }
2215
2216 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2217 return g1_policy();
2218 }
2219
2220 size_t G1CollectedHeap::capacity() const {
2221 return _hrm.length() * HeapRegion::GrainBytes;
2222 }
2223
2224 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2225 assert(!hr->is_continues_humongous(), "pre-condition");
2226 hr->reset_gc_time_stamp();
2227 if (hr->is_starts_humongous()) {
2228 uint first_index = hr->hrm_index() + 1;
2229 uint last_index = hr->last_hc_index();
2230 for (uint i = first_index; i < last_index; i += 1) {
2231 HeapRegion* chr = region_at(i);
2232 assert(chr->is_continues_humongous(), "sanity");
2233 chr->reset_gc_time_stamp();
2234 }
2235 }
2236 }
2237
2238 #ifndef PRODUCT
2239
2240 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2241 private:
2242 unsigned _gc_time_stamp;
2243 bool _failures;
2244
2245 public:
2246 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2247 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2248
2249 virtual bool doHeapRegion(HeapRegion* hr) {
2250 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2251 if (_gc_time_stamp != region_gc_time_stamp) {
2252 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2253 "expected %d", HR_FORMAT_PARAMS(hr),
2254 region_gc_time_stamp, _gc_time_stamp);
2255 _failures = true;
2256 }
2257 return false;
2258 }
2259
2260 bool failures() { return _failures; }
2261 };
2262
2263 void G1CollectedHeap::check_gc_time_stamps() {
2264 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2265 heap_region_iterate(&cl);
2266 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2267 }
2268 #endif // PRODUCT
2269
2270 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2271 _cg1r->hot_card_cache()->drain(cl, worker_i);
2272 }
2273
2274 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2275 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2276 size_t n_completed_buffers = 0;
2277 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2278 n_completed_buffers++;
2279 }
2280 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2281 dcqs.clear_n_completed_buffers();
2282 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2283 }
2284
2285 // Computes the sum of the storage used by the various regions.
2286 size_t G1CollectedHeap::used() const {
2287 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2288 if (_archive_allocator != NULL) {
2289 result += _archive_allocator->used();
2290 }
2291 return result;
2292 }
2293
2294 size_t G1CollectedHeap::used_unlocked() const {
2295 return _summary_bytes_used;
2296 }
2297
2298 class SumUsedClosure: public HeapRegionClosure {
2299 size_t _used;
2300 public:
2301 SumUsedClosure() : _used(0) {}
2302 bool doHeapRegion(HeapRegion* r) {
2303 if (!r->is_continues_humongous()) {
2304 _used += r->used();
2305 }
2306 return false;
2307 }
2308 size_t result() { return _used; }
2309 };
2310
2311 size_t G1CollectedHeap::recalculate_used() const {
2312 double recalculate_used_start = os::elapsedTime();
2313
2314 SumUsedClosure blk;
2315 heap_region_iterate(&blk);
2316
2317 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2318 return blk.result();
2319 }
2320
2321 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2322 switch (cause) {
2323 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2324 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2325 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2326 case GCCause::_g1_humongous_allocation: return true;
2327 case GCCause::_update_allocation_context_stats_inc: return true;
2328 case GCCause::_wb_conc_mark: return true;
2329 default: return false;
2330 }
2331 }
2332
2333 #ifndef PRODUCT
2334 void G1CollectedHeap::allocate_dummy_regions() {
2335 // Let's fill up most of the region
2336 size_t word_size = HeapRegion::GrainWords - 1024;
2337 // And as a result the region we'll allocate will be humongous.
2338 guarantee(is_humongous(word_size), "sanity");
2339
2340 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2341 // Let's use the existing mechanism for the allocation
2342 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2343 AllocationContext::system());
2344 if (dummy_obj != NULL) {
2345 MemRegion mr(dummy_obj, word_size);
2346 CollectedHeap::fill_with_object(mr);
2347 } else {
2348 // If we can't allocate once, we probably cannot allocate
2349 // again. Let's get out of the loop.
2350 break;
2351 }
2352 }
2353 }
2354 #endif // !PRODUCT
2355
2356 void G1CollectedHeap::increment_old_marking_cycles_started() {
2357 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2358 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2359 "Wrong marking cycle count (started: %d, completed: %d)",
2360 _old_marking_cycles_started, _old_marking_cycles_completed);
2361
2362 _old_marking_cycles_started++;
2363 }
2364
2365 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2366 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2367
2368 // We assume that if concurrent == true, then the caller is a
2369 // concurrent thread that was joined the Suspendible Thread
2370 // Set. If there's ever a cheap way to check this, we should add an
2371 // assert here.
2372
2373 // Given that this method is called at the end of a Full GC or of a
2374 // concurrent cycle, and those can be nested (i.e., a Full GC can
2375 // interrupt a concurrent cycle), the number of full collections
2376 // completed should be either one (in the case where there was no
2377 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2378 // behind the number of full collections started.
2379
2380 // This is the case for the inner caller, i.e. a Full GC.
2381 assert(concurrent ||
2382 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2383 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2384 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2385 "is inconsistent with _old_marking_cycles_completed = %u",
2386 _old_marking_cycles_started, _old_marking_cycles_completed);
2387
2388 // This is the case for the outer caller, i.e. the concurrent cycle.
2389 assert(!concurrent ||
2390 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2391 "for outer caller (concurrent cycle): "
2392 "_old_marking_cycles_started = %u "
2393 "is inconsistent with _old_marking_cycles_completed = %u",
2394 _old_marking_cycles_started, _old_marking_cycles_completed);
2395
2396 _old_marking_cycles_completed += 1;
2397
2398 // We need to clear the "in_progress" flag in the CM thread before
2399 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2400 // is set) so that if a waiter requests another System.gc() it doesn't
2401 // incorrectly see that a marking cycle is still in progress.
2402 if (concurrent) {
2403 _cmThread->set_idle();
2404 }
2405
2406 // This notify_all() will ensure that a thread that called
2407 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2408 // and it's waiting for a full GC to finish will be woken up. It is
2409 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2410 FullGCCount_lock->notify_all();
2411 }
2412
2413 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2414 GCIdMarkAndRestore conc_gc_id_mark;
2415 collector_state()->set_concurrent_cycle_started(true);
2416 _gc_timer_cm->register_gc_start(start_time);
2417
2418 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2419 trace_heap_before_gc(_gc_tracer_cm);
2420 _cmThread->set_gc_id(GCId::current());
2421 }
2422
2423 void G1CollectedHeap::register_concurrent_cycle_end() {
2424 if (collector_state()->concurrent_cycle_started()) {
2425 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2426 if (_cm->has_aborted()) {
2427 _gc_tracer_cm->report_concurrent_mode_failure();
2428 }
2429
2430 _gc_timer_cm->register_gc_end();
2431 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2432
2433 // Clear state variables to prepare for the next concurrent cycle.
2434 collector_state()->set_concurrent_cycle_started(false);
2435 _heap_summary_sent = false;
2436 }
2437 }
2438
2439 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2440 if (collector_state()->concurrent_cycle_started()) {
2441 // This function can be called when:
2442 // the cleanup pause is run
2443 // the concurrent cycle is aborted before the cleanup pause.
2444 // the concurrent cycle is aborted after the cleanup pause,
2445 // but before the concurrent cycle end has been registered.
2446 // Make sure that we only send the heap information once.
2447 if (!_heap_summary_sent) {
2448 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2449 trace_heap_after_gc(_gc_tracer_cm);
2450 _heap_summary_sent = true;
2451 }
2452 }
2453 }
2454
2455 void G1CollectedHeap::collect(GCCause::Cause cause) {
2456 assert_heap_not_locked();
2457
2458 uint gc_count_before;
2459 uint old_marking_count_before;
2460 uint full_gc_count_before;
2461 bool retry_gc;
2462
2463 do {
2464 retry_gc = false;
2465
2466 {
2467 MutexLocker ml(Heap_lock);
2468
2469 // Read the GC count while holding the Heap_lock
2470 gc_count_before = total_collections();
2471 full_gc_count_before = total_full_collections();
2472 old_marking_count_before = _old_marking_cycles_started;
2473 }
2474
2475 if (should_do_concurrent_full_gc(cause)) {
2476 // Schedule an initial-mark evacuation pause that will start a
2477 // concurrent cycle. We're setting word_size to 0 which means that
2478 // we are not requesting a post-GC allocation.
2479 VM_G1IncCollectionPause op(gc_count_before,
2480 0, /* word_size */
2481 true, /* should_initiate_conc_mark */
2482 g1_policy()->max_pause_time_ms(),
2483 cause);
2484 op.set_allocation_context(AllocationContext::current());
2485
2486 VMThread::execute(&op);
2487 if (!op.pause_succeeded()) {
2488 if (old_marking_count_before == _old_marking_cycles_started) {
2489 retry_gc = op.should_retry_gc();
2490 } else {
2491 // A Full GC happened while we were trying to schedule the
2492 // initial-mark GC. No point in starting a new cycle given
2493 // that the whole heap was collected anyway.
2494 }
2495
2496 if (retry_gc) {
2497 if (GC_locker::is_active_and_needs_gc()) {
2498 GC_locker::stall_until_clear();
2499 }
2500 }
2501 }
2502 } else {
2503 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2504 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2505
2506 // Schedule a standard evacuation pause. We're setting word_size
2507 // to 0 which means that we are not requesting a post-GC allocation.
2508 VM_G1IncCollectionPause op(gc_count_before,
2509 0, /* word_size */
2510 false, /* should_initiate_conc_mark */
2511 g1_policy()->max_pause_time_ms(),
2512 cause);
2513 VMThread::execute(&op);
2514 } else {
2515 // Schedule a Full GC.
2516 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2517 VMThread::execute(&op);
2518 }
2519 }
2520 } while (retry_gc);
2521 }
2522
2523 bool G1CollectedHeap::is_in(const void* p) const {
2524 if (_hrm.reserved().contains(p)) {
2525 // Given that we know that p is in the reserved space,
2526 // heap_region_containing_raw() should successfully
2527 // return the containing region.
2528 HeapRegion* hr = heap_region_containing_raw(p);
2529 return hr->is_in(p);
2530 } else {
2531 return false;
2532 }
2533 }
2534
2535 #ifdef ASSERT
2536 bool G1CollectedHeap::is_in_exact(const void* p) const {
2537 bool contains = reserved_region().contains(p);
2538 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2539 if (contains && available) {
2540 return true;
2541 } else {
2542 return false;
2543 }
2544 }
2545 #endif
2546
2547 bool G1CollectedHeap::obj_in_cs(oop obj) {
2548 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2549 return r != NULL && r->in_collection_set();
2550 }
2551
2552 // Iteration functions.
2553
2554 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2555
2556 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2557 ExtendedOopClosure* _cl;
2558 public:
2559 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2560 bool doHeapRegion(HeapRegion* r) {
2561 if (!r->is_continues_humongous()) {
2562 r->oop_iterate(_cl);
2563 }
2564 return false;
2565 }
2566 };
2567
2568 // Iterates an ObjectClosure over all objects within a HeapRegion.
2569
2570 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2571 ObjectClosure* _cl;
2572 public:
2573 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2574 bool doHeapRegion(HeapRegion* r) {
2575 if (!r->is_continues_humongous()) {
2576 r->object_iterate(_cl);
2577 }
2578 return false;
2579 }
2580 };
2581
2582 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2583 IterateObjectClosureRegionClosure blk(cl);
2584 heap_region_iterate(&blk);
2585 }
2586
2587 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2588 _hrm.iterate(cl);
2589 }
2590
2591 void
2592 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2593 uint worker_id,
2594 HeapRegionClaimer *hrclaimer,
2595 bool concurrent) const {
2596 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2597 }
2598
2599 // Clear the cached CSet starting regions and (more importantly)
2600 // the time stamps. Called when we reset the GC time stamp.
2601 void G1CollectedHeap::clear_cset_start_regions() {
2602 assert(_worker_cset_start_region != NULL, "sanity");
2603 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2604
2605 for (uint i = 0; i < ParallelGCThreads; i++) {
2606 _worker_cset_start_region[i] = NULL;
2607 _worker_cset_start_region_time_stamp[i] = 0;
2608 }
2609 }
2610
2611 // Given the id of a worker, obtain or calculate a suitable
2612 // starting region for iterating over the current collection set.
2613 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2614 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2615
2616 HeapRegion* result = NULL;
2617 unsigned gc_time_stamp = get_gc_time_stamp();
2618
2619 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2620 // Cached starting region for current worker was set
2621 // during the current pause - so it's valid.
2622 // Note: the cached starting heap region may be NULL
2623 // (when the collection set is empty).
2624 result = _worker_cset_start_region[worker_i];
2625 assert(result == NULL || result->in_collection_set(), "sanity");
2626 return result;
2627 }
2628
2629 // The cached entry was not valid so let's calculate
2630 // a suitable starting heap region for this worker.
2631
2632 // We want the parallel threads to start their collection
2633 // set iteration at different collection set regions to
2634 // avoid contention.
2635 // If we have:
2636 // n collection set regions
2637 // p threads
2638 // Then thread t will start at region floor ((t * n) / p)
2639
2640 result = g1_policy()->collection_set();
2641 uint cs_size = g1_policy()->cset_region_length();
2642 uint active_workers = workers()->active_workers();
2643
2644 uint end_ind = (cs_size * worker_i) / active_workers;
2645 uint start_ind = 0;
2646
2647 if (worker_i > 0 &&
2648 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2649 // Previous workers starting region is valid
2650 // so let's iterate from there
2651 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2652 result = _worker_cset_start_region[worker_i - 1];
2653 }
2654
2655 for (uint i = start_ind; i < end_ind; i++) {
2656 result = result->next_in_collection_set();
2657 }
2658
2659 // Note: the calculated starting heap region may be NULL
2660 // (when the collection set is empty).
2661 assert(result == NULL || result->in_collection_set(), "sanity");
2662 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2663 "should be updated only once per pause");
2664 _worker_cset_start_region[worker_i] = result;
2665 OrderAccess::storestore();
2666 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2667 return result;
2668 }
2669
2670 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2671 HeapRegion* r = g1_policy()->collection_set();
2672 while (r != NULL) {
2673 HeapRegion* next = r->next_in_collection_set();
2674 if (cl->doHeapRegion(r)) {
2675 cl->incomplete();
2676 return;
2677 }
2678 r = next;
2679 }
2680 }
2681
2682 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2683 HeapRegionClosure *cl) {
2684 if (r == NULL) {
2685 // The CSet is empty so there's nothing to do.
2686 return;
2687 }
2688
2689 assert(r->in_collection_set(),
2690 "Start region must be a member of the collection set.");
2691 HeapRegion* cur = r;
2692 while (cur != NULL) {
2693 HeapRegion* next = cur->next_in_collection_set();
2694 if (cl->doHeapRegion(cur) && false) {
2695 cl->incomplete();
2696 return;
2697 }
2698 cur = next;
2699 }
2700 cur = g1_policy()->collection_set();
2701 while (cur != r) {
2702 HeapRegion* next = cur->next_in_collection_set();
2703 if (cl->doHeapRegion(cur) && false) {
2704 cl->incomplete();
2705 return;
2706 }
2707 cur = next;
2708 }
2709 }
2710
2711 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2712 HeapRegion* result = _hrm.next_region_in_heap(from);
2713 while (result != NULL && result->is_pinned()) {
2714 result = _hrm.next_region_in_heap(result);
2715 }
2716 return result;
2717 }
2718
2719 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2720 HeapRegion* hr = heap_region_containing(addr);
2721 return hr->block_start(addr);
2722 }
2723
2724 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2725 HeapRegion* hr = heap_region_containing(addr);
2726 return hr->block_size(addr);
2727 }
2728
2729 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2730 HeapRegion* hr = heap_region_containing(addr);
2731 return hr->block_is_obj(addr);
2732 }
2733
2734 bool G1CollectedHeap::supports_tlab_allocation() const {
2735 return true;
2736 }
2737
2738 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2739 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2740 }
2741
2742 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2743 return young_list()->eden_used_bytes();
2744 }
2745
2746 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2747 // must be equal to the humongous object limit.
2748 size_t G1CollectedHeap::max_tlab_size() const {
2749 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2750 }
2751
2752 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2753 AllocationContext_t context = AllocationContext::current();
2754 return _allocator->unsafe_max_tlab_alloc(context);
2755 }
2756
2757 size_t G1CollectedHeap::max_capacity() const {
2758 return _hrm.reserved().byte_size();
2759 }
2760
2761 jlong G1CollectedHeap::millis_since_last_gc() {
2762 // assert(false, "NYI");
2763 return 0;
2764 }
2765
2766 void G1CollectedHeap::prepare_for_verify() {
2767 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2768 ensure_parsability(false);
2769 }
2770 g1_rem_set()->prepare_for_verify();
2771 }
2772
2773 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2774 VerifyOption vo) {
2775 switch (vo) {
2776 case VerifyOption_G1UsePrevMarking:
2777 return hr->obj_allocated_since_prev_marking(obj);
2778 case VerifyOption_G1UseNextMarking:
2779 return hr->obj_allocated_since_next_marking(obj);
2780 case VerifyOption_G1UseMarkWord:
2781 return false;
2782 default:
2783 ShouldNotReachHere();
2784 }
2785 return false; // keep some compilers happy
2786 }
2787
2788 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2789 switch (vo) {
2790 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2791 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2792 case VerifyOption_G1UseMarkWord: return NULL;
2793 default: ShouldNotReachHere();
2794 }
2795 return NULL; // keep some compilers happy
2796 }
2797
2798 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2799 switch (vo) {
2800 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2801 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2802 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2803 default: ShouldNotReachHere();
2804 }
2805 return false; // keep some compilers happy
2806 }
2807
2808 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2809 switch (vo) {
2810 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2811 case VerifyOption_G1UseNextMarking: return "NTAMS";
2812 case VerifyOption_G1UseMarkWord: return "NONE";
2813 default: ShouldNotReachHere();
2814 }
2815 return NULL; // keep some compilers happy
2816 }
2817
2818 class VerifyRootsClosure: public OopClosure {
2819 private:
2820 G1CollectedHeap* _g1h;
2821 VerifyOption _vo;
2822 bool _failures;
2823 public:
2824 // _vo == UsePrevMarking -> use "prev" marking information,
2825 // _vo == UseNextMarking -> use "next" marking information,
2826 // _vo == UseMarkWord -> use mark word from object header.
2827 VerifyRootsClosure(VerifyOption vo) :
2828 _g1h(G1CollectedHeap::heap()),
2829 _vo(vo),
2830 _failures(false) { }
2831
2832 bool failures() { return _failures; }
2833
2834 template <class T> void do_oop_nv(T* p) {
2835 T heap_oop = oopDesc::load_heap_oop(p);
2836 if (!oopDesc::is_null(heap_oop)) {
2837 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2838 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2839 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2840 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2841 if (_vo == VerifyOption_G1UseMarkWord) {
2842 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2843 }
2844 obj->print_on(gclog_or_tty);
2845 _failures = true;
2846 }
2847 }
2848 }
2849
2850 void do_oop(oop* p) { do_oop_nv(p); }
2851 void do_oop(narrowOop* p) { do_oop_nv(p); }
2852 };
2853
2854 class G1VerifyCodeRootOopClosure: public OopClosure {
2855 G1CollectedHeap* _g1h;
2856 OopClosure* _root_cl;
2857 nmethod* _nm;
2858 VerifyOption _vo;
2859 bool _failures;
2860
2861 template <class T> void do_oop_work(T* p) {
2862 // First verify that this root is live
2863 _root_cl->do_oop(p);
2864
2865 if (!G1VerifyHeapRegionCodeRoots) {
2866 // We're not verifying the code roots attached to heap region.
2867 return;
2868 }
2869
2870 // Don't check the code roots during marking verification in a full GC
2871 if (_vo == VerifyOption_G1UseMarkWord) {
2872 return;
2873 }
2874
2875 // Now verify that the current nmethod (which contains p) is
2876 // in the code root list of the heap region containing the
2877 // object referenced by p.
2878
2879 T heap_oop = oopDesc::load_heap_oop(p);
2880 if (!oopDesc::is_null(heap_oop)) {
2881 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2882
2883 // Now fetch the region containing the object
2884 HeapRegion* hr = _g1h->heap_region_containing(obj);
2885 HeapRegionRemSet* hrrs = hr->rem_set();
2886 // Verify that the strong code root list for this region
2887 // contains the nmethod
2888 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2889 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2890 "from nmethod " PTR_FORMAT " not in strong "
2891 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2892 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2893 _failures = true;
2894 }
2895 }
2896 }
2897
2898 public:
2899 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2900 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2901
2902 void do_oop(oop* p) { do_oop_work(p); }
2903 void do_oop(narrowOop* p) { do_oop_work(p); }
2904
2905 void set_nmethod(nmethod* nm) { _nm = nm; }
2906 bool failures() { return _failures; }
2907 };
2908
2909 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2910 G1VerifyCodeRootOopClosure* _oop_cl;
2911
2912 public:
2913 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2914 _oop_cl(oop_cl) {}
2915
2916 void do_code_blob(CodeBlob* cb) {
2917 nmethod* nm = cb->as_nmethod_or_null();
2918 if (nm != NULL) {
2919 _oop_cl->set_nmethod(nm);
2920 nm->oops_do(_oop_cl);
2921 }
2922 }
2923 };
2924
2925 class YoungRefCounterClosure : public OopClosure {
2926 G1CollectedHeap* _g1h;
2927 int _count;
2928 public:
2929 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2930 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2931 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2932
2933 int count() { return _count; }
2934 void reset_count() { _count = 0; };
2935 };
2936
2937 class VerifyKlassClosure: public KlassClosure {
2938 YoungRefCounterClosure _young_ref_counter_closure;
2939 OopClosure *_oop_closure;
2940 public:
2941 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2942 void do_klass(Klass* k) {
2943 k->oops_do(_oop_closure);
2944
2945 _young_ref_counter_closure.reset_count();
2946 k->oops_do(&_young_ref_counter_closure);
2947 if (_young_ref_counter_closure.count() > 0) {
2948 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2949 }
2950 }
2951 };
2952
2953 class VerifyLivenessOopClosure: public OopClosure {
2954 G1CollectedHeap* _g1h;
2955 VerifyOption _vo;
2956 public:
2957 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2958 _g1h(g1h), _vo(vo)
2959 { }
2960 void do_oop(narrowOop *p) { do_oop_work(p); }
2961 void do_oop( oop *p) { do_oop_work(p); }
2962
2963 template <class T> void do_oop_work(T *p) {
2964 oop obj = oopDesc::load_decode_heap_oop(p);
2965 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2966 "Dead object referenced by a not dead object");
2967 }
2968 };
2969
2970 class VerifyObjsInRegionClosure: public ObjectClosure {
2971 private:
2972 G1CollectedHeap* _g1h;
2973 size_t _live_bytes;
2974 HeapRegion *_hr;
2975 VerifyOption _vo;
2976 public:
2977 // _vo == UsePrevMarking -> use "prev" marking information,
2978 // _vo == UseNextMarking -> use "next" marking information,
2979 // _vo == UseMarkWord -> use mark word from object header.
2980 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2981 : _live_bytes(0), _hr(hr), _vo(vo) {
2982 _g1h = G1CollectedHeap::heap();
2983 }
2984 void do_object(oop o) {
2985 VerifyLivenessOopClosure isLive(_g1h, _vo);
2986 assert(o != NULL, "Huh?");
2987 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2988 // If the object is alive according to the mark word,
2989 // then verify that the marking information agrees.
2990 // Note we can't verify the contra-positive of the
2991 // above: if the object is dead (according to the mark
2992 // word), it may not be marked, or may have been marked
2993 // but has since became dead, or may have been allocated
2994 // since the last marking.
2995 if (_vo == VerifyOption_G1UseMarkWord) {
2996 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2997 }
2998
2999 o->oop_iterate_no_header(&isLive);
3000 if (!_hr->obj_allocated_since_prev_marking(o)) {
3001 size_t obj_size = o->size(); // Make sure we don't overflow
3002 _live_bytes += (obj_size * HeapWordSize);
3003 }
3004 }
3005 }
3006 size_t live_bytes() { return _live_bytes; }
3007 };
3008
3009 class VerifyArchiveOopClosure: public OopClosure {
3010 public:
3011 VerifyArchiveOopClosure(HeapRegion *hr) { }
3012 void do_oop(narrowOop *p) { do_oop_work(p); }
3013 void do_oop( oop *p) { do_oop_work(p); }
3014
3015 template <class T> void do_oop_work(T *p) {
3016 oop obj = oopDesc::load_decode_heap_oop(p);
3017 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3018 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3019 p2i(p), p2i(obj));
3020 }
3021 };
3022
3023 class VerifyArchiveRegionClosure: public ObjectClosure {
3024 public:
3025 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3026 // Verify that all object pointers are to archive regions.
3027 void do_object(oop o) {
3028 VerifyArchiveOopClosure checkOop(NULL);
3029 assert(o != NULL, "Should not be here for NULL oops");
3030 o->oop_iterate_no_header(&checkOop);
3031 }
3032 };
3033
3034 class VerifyRegionClosure: public HeapRegionClosure {
3035 private:
3036 bool _par;
3037 VerifyOption _vo;
3038 bool _failures;
3039 public:
3040 // _vo == UsePrevMarking -> use "prev" marking information,
3041 // _vo == UseNextMarking -> use "next" marking information,
3042 // _vo == UseMarkWord -> use mark word from object header.
3043 VerifyRegionClosure(bool par, VerifyOption vo)
3044 : _par(par),
3045 _vo(vo),
3046 _failures(false) {}
3047
3048 bool failures() {
3049 return _failures;
3050 }
3051
3052 bool doHeapRegion(HeapRegion* r) {
3053 // For archive regions, verify there are no heap pointers to
3054 // non-pinned regions. For all others, verify liveness info.
3055 if (r->is_archive()) {
3056 VerifyArchiveRegionClosure verify_oop_pointers(r);
3057 r->object_iterate(&verify_oop_pointers);
3058 return true;
3059 }
3060 if (!r->is_continues_humongous()) {
3061 bool failures = false;
3062 r->verify(_vo, &failures);
3063 if (failures) {
3064 _failures = true;
3065 } else {
3066 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3067 r->object_iterate(¬_dead_yet_cl);
3068 if (_vo != VerifyOption_G1UseNextMarking) {
3069 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3070 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3071 "max_live_bytes " SIZE_FORMAT " "
3072 "< calculated " SIZE_FORMAT,
3073 p2i(r->bottom()), p2i(r->end()),
3074 r->max_live_bytes(),
3075 not_dead_yet_cl.live_bytes());
3076 _failures = true;
3077 }
3078 } else {
3079 // When vo == UseNextMarking we cannot currently do a sanity
3080 // check on the live bytes as the calculation has not been
3081 // finalized yet.
3082 }
3083 }
3084 }
3085 return false; // stop the region iteration if we hit a failure
3086 }
3087 };
3088
3089 // This is the task used for parallel verification of the heap regions
3090
3091 class G1ParVerifyTask: public AbstractGangTask {
3092 private:
3093 G1CollectedHeap* _g1h;
3094 VerifyOption _vo;
3095 bool _failures;
3096 HeapRegionClaimer _hrclaimer;
3097
3098 public:
3099 // _vo == UsePrevMarking -> use "prev" marking information,
3100 // _vo == UseNextMarking -> use "next" marking information,
3101 // _vo == UseMarkWord -> use mark word from object header.
3102 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3103 AbstractGangTask("Parallel verify task"),
3104 _g1h(g1h),
3105 _vo(vo),
3106 _failures(false),
3107 _hrclaimer(g1h->workers()->active_workers()) {}
3108
3109 bool failures() {
3110 return _failures;
3111 }
3112
3113 void work(uint worker_id) {
3114 HandleMark hm;
3115 VerifyRegionClosure blk(true, _vo);
3116 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3117 if (blk.failures()) {
3118 _failures = true;
3119 }
3120 }
3121 };
3122
3123 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3124 if (SafepointSynchronize::is_at_safepoint()) {
3125 assert(Thread::current()->is_VM_thread(),
3126 "Expected to be executed serially by the VM thread at this point");
3127
3128 if (!silent) { gclog_or_tty->print("Roots "); }
3129 VerifyRootsClosure rootsCl(vo);
3130 VerifyKlassClosure klassCl(this, &rootsCl);
3131 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3132
3133 // We apply the relevant closures to all the oops in the
3134 // system dictionary, class loader data graph, the string table
3135 // and the nmethods in the code cache.
3136 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3137 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3138
3139 {
3140 G1RootProcessor root_processor(this, 1);
3141 root_processor.process_all_roots(&rootsCl,
3142 &cldCl,
3143 &blobsCl);
3144 }
3145
3146 bool failures = rootsCl.failures() || codeRootsCl.failures();
3147
3148 if (vo != VerifyOption_G1UseMarkWord) {
3149 // If we're verifying during a full GC then the region sets
3150 // will have been torn down at the start of the GC. Therefore
3151 // verifying the region sets will fail. So we only verify
3152 // the region sets when not in a full GC.
3153 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3154 verify_region_sets();
3155 }
3156
3157 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3158 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3159
3160 G1ParVerifyTask task(this, vo);
3161 workers()->run_task(&task);
3162 if (task.failures()) {
3163 failures = true;
3164 }
3165
3166 } else {
3167 VerifyRegionClosure blk(false, vo);
3168 heap_region_iterate(&blk);
3169 if (blk.failures()) {
3170 failures = true;
3171 }
3172 }
3173
3174 if (G1StringDedup::is_enabled()) {
3175 if (!silent) gclog_or_tty->print("StrDedup ");
3176 G1StringDedup::verify();
3177 }
3178
3179 if (failures) {
3180 gclog_or_tty->print_cr("Heap:");
3181 // It helps to have the per-region information in the output to
3182 // help us track down what went wrong. This is why we call
3183 // print_extended_on() instead of print_on().
3184 print_extended_on(gclog_or_tty);
3185 gclog_or_tty->cr();
3186 gclog_or_tty->flush();
3187 }
3188 guarantee(!failures, "there should not have been any failures");
3189 } else {
3190 if (!silent) {
3191 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3192 if (G1StringDedup::is_enabled()) {
3193 gclog_or_tty->print(", StrDedup");
3194 }
3195 gclog_or_tty->print(") ");
3196 }
3197 }
3198 }
3199
3200 void G1CollectedHeap::verify(bool silent) {
3201 verify(silent, VerifyOption_G1UsePrevMarking);
3202 }
3203
3204 double G1CollectedHeap::verify(bool guard, const char* msg) {
3205 double verify_time_ms = 0.0;
3206
3207 if (guard && total_collections() >= VerifyGCStartAt) {
3208 double verify_start = os::elapsedTime();
3209 HandleMark hm; // Discard invalid handles created during verification
3210 prepare_for_verify();
3211 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3212 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3213 }
3214
3215 return verify_time_ms;
3216 }
3217
3218 void G1CollectedHeap::verify_before_gc() {
3219 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3220 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3221 }
3222
3223 void G1CollectedHeap::verify_after_gc() {
3224 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3225 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3226 }
3227
3228 class PrintRegionClosure: public HeapRegionClosure {
3229 outputStream* _st;
3230 public:
3231 PrintRegionClosure(outputStream* st) : _st(st) {}
3232 bool doHeapRegion(HeapRegion* r) {
3233 r->print_on(_st);
3234 return false;
3235 }
3236 };
3237
3238 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3239 const HeapRegion* hr,
3240 const VerifyOption vo) const {
3241 switch (vo) {
3242 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3243 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3244 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3245 default: ShouldNotReachHere();
3246 }
3247 return false; // keep some compilers happy
3248 }
3249
3250 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3251 const VerifyOption vo) const {
3252 switch (vo) {
3253 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3254 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3255 case VerifyOption_G1UseMarkWord: {
3256 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3257 return !obj->is_gc_marked() && !hr->is_archive();
3258 }
3259 default: ShouldNotReachHere();
3260 }
3261 return false; // keep some compilers happy
3262 }
3263
3264 void G1CollectedHeap::print_on(outputStream* st) const {
3265 st->print(" %-20s", "garbage-first heap");
3266 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3267 capacity()/K, used_unlocked()/K);
3268 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3269 p2i(_hrm.reserved().start()),
3270 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3271 p2i(_hrm.reserved().end()));
3272 st->cr();
3273 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3274 uint young_regions = _young_list->length();
3275 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3276 (size_t) young_regions * HeapRegion::GrainBytes / K);
3277 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3278 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3279 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3280 st->cr();
3281 MetaspaceAux::print_on(st);
3282 }
3283
3284 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3285 print_on(st);
3286
3287 // Print the per-region information.
3288 st->cr();
3289 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3290 "HS=humongous(starts), HC=humongous(continues), "
3291 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3292 "PTAMS=previous top-at-mark-start, "
3293 "NTAMS=next top-at-mark-start)");
3294 PrintRegionClosure blk(st);
3295 heap_region_iterate(&blk);
3296 }
3297
3298 void G1CollectedHeap::print_on_error(outputStream* st) const {
3299 this->CollectedHeap::print_on_error(st);
3300
3301 if (_cm != NULL) {
3302 st->cr();
3303 _cm->print_on_error(st);
3304 }
3305 }
3306
3307 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3308 workers()->print_worker_threads_on(st);
3309 _cmThread->print_on(st);
3310 st->cr();
3311 _cm->print_worker_threads_on(st);
3312 _cg1r->print_worker_threads_on(st);
3313 if (G1StringDedup::is_enabled()) {
3314 G1StringDedup::print_worker_threads_on(st);
3315 }
3316 }
3317
3318 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3319 workers()->threads_do(tc);
3320 tc->do_thread(_cmThread);
3321 _cg1r->threads_do(tc);
3322 if (G1StringDedup::is_enabled()) {
3323 G1StringDedup::threads_do(tc);
3324 }
3325 }
3326
3327 void G1CollectedHeap::print_tracing_info() const {
3328 // We'll overload this to mean "trace GC pause statistics."
3329 if (TraceYoungGenTime || TraceOldGenTime) {
3330 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3331 // to that.
3332 g1_policy()->print_tracing_info();
3333 }
3334 if (G1SummarizeRSetStats) {
3335 g1_rem_set()->print_summary_info();
3336 }
3337 if (G1SummarizeConcMark) {
3338 concurrent_mark()->print_summary_info();
3339 }
3340 g1_policy()->print_yg_surv_rate_info();
3341 }
3342
3343 #ifndef PRODUCT
3344 // Helpful for debugging RSet issues.
3345
3346 class PrintRSetsClosure : public HeapRegionClosure {
3347 private:
3348 const char* _msg;
3349 size_t _occupied_sum;
3350
3351 public:
3352 bool doHeapRegion(HeapRegion* r) {
3353 HeapRegionRemSet* hrrs = r->rem_set();
3354 size_t occupied = hrrs->occupied();
3355 _occupied_sum += occupied;
3356
3357 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3358 HR_FORMAT_PARAMS(r));
3359 if (occupied == 0) {
3360 gclog_or_tty->print_cr(" RSet is empty");
3361 } else {
3362 hrrs->print();
3363 }
3364 gclog_or_tty->print_cr("----------");
3365 return false;
3366 }
3367
3368 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3369 gclog_or_tty->cr();
3370 gclog_or_tty->print_cr("========================================");
3371 gclog_or_tty->print_cr("%s", msg);
3372 gclog_or_tty->cr();
3373 }
3374
3375 ~PrintRSetsClosure() {
3376 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3377 gclog_or_tty->print_cr("========================================");
3378 gclog_or_tty->cr();
3379 }
3380 };
3381
3382 void G1CollectedHeap::print_cset_rsets() {
3383 PrintRSetsClosure cl("Printing CSet RSets");
3384 collection_set_iterate(&cl);
3385 }
3386
3387 void G1CollectedHeap::print_all_rsets() {
3388 PrintRSetsClosure cl("Printing All RSets");;
3389 heap_region_iterate(&cl);
3390 }
3391 #endif // PRODUCT
3392
3393 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3394 YoungList* young_list = heap()->young_list();
3395
3396 size_t eden_used_bytes = young_list->eden_used_bytes();
3397 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3398
3399 size_t eden_capacity_bytes =
3400 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3401
3402 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3403 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3404 }
3405
3406 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3407 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3408 stats->unused(), stats->used(), stats->region_end_waste(),
3409 stats->regions_filled(), stats->direct_allocated(),
3410 stats->failure_used(), stats->failure_waste());
3411 }
3412
3413 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3414 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3415 gc_tracer->report_gc_heap_summary(when, heap_summary);
3416
3417 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3418 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3419 }
3420
3421
3422 G1CollectedHeap* G1CollectedHeap::heap() {
3423 CollectedHeap* heap = Universe::heap();
3424 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3425 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3426 return (G1CollectedHeap*)heap;
3427 }
3428
3429 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3430 // always_do_update_barrier = false;
3431 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3432 // Fill TLAB's and such
3433 accumulate_statistics_all_tlabs();
3434 ensure_parsability(true);
3435
3436 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3437 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3438 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3439 }
3440 }
3441
3442 void G1CollectedHeap::gc_epilogue(bool full) {
3443
3444 if (G1SummarizeRSetStats &&
3445 (G1SummarizeRSetStatsPeriod > 0) &&
3446 // we are at the end of the GC. Total collections has already been increased.
3447 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3448 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3449 }
3450
3451 // FIXME: what is this about?
3452 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3453 // is set.
3454 #if defined(COMPILER2) || INCLUDE_JVMCI
3455 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3456 #endif
3457 // always_do_update_barrier = true;
3458
3459 resize_all_tlabs();
3460 allocation_context_stats().update(full);
3461
3462 // We have just completed a GC. Update the soft reference
3463 // policy with the new heap occupancy
3464 Universe::update_heap_info_at_gc();
3465 }
3466
3467 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3468 uint gc_count_before,
3469 bool* succeeded,
3470 GCCause::Cause gc_cause) {
3471 assert_heap_not_locked_and_not_at_safepoint();
3472 g1_policy()->record_stop_world_start();
3473 VM_G1IncCollectionPause op(gc_count_before,
3474 word_size,
3475 false, /* should_initiate_conc_mark */
3476 g1_policy()->max_pause_time_ms(),
3477 gc_cause);
3478
3479 op.set_allocation_context(AllocationContext::current());
3480 VMThread::execute(&op);
3481
3482 HeapWord* result = op.result();
3483 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3484 assert(result == NULL || ret_succeeded,
3485 "the result should be NULL if the VM did not succeed");
3486 *succeeded = ret_succeeded;
3487
3488 assert_heap_not_locked();
3489 return result;
3490 }
3491
3492 void
3493 G1CollectedHeap::doConcurrentMark() {
3494 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3495 if (!_cmThread->in_progress()) {
3496 _cmThread->set_started();
3497 CGC_lock->notify();
3498 }
3499 }
3500
3501 size_t G1CollectedHeap::pending_card_num() {
3502 size_t extra_cards = 0;
3503 JavaThread *curr = Threads::first();
3504 while (curr != NULL) {
3505 DirtyCardQueue& dcq = curr->dirty_card_queue();
3506 extra_cards += dcq.size();
3507 curr = curr->next();
3508 }
3509 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3510 size_t buffer_size = dcqs.buffer_size();
3511 size_t buffer_num = dcqs.completed_buffers_num();
3512
3513 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3514 // in bytes - not the number of 'entries'. We need to convert
3515 // into a number of cards.
3516 return (buffer_size * buffer_num + extra_cards) / oopSize;
3517 }
3518
3519 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3520 private:
3521 size_t _total_humongous;
3522 size_t _candidate_humongous;
3523
3524 DirtyCardQueue _dcq;
3525
3526 // We don't nominate objects with many remembered set entries, on
3527 // the assumption that such objects are likely still live.
3528 bool is_remset_small(HeapRegion* region) const {
3529 HeapRegionRemSet* const rset = region->rem_set();
3530 return G1EagerReclaimHumongousObjectsWithStaleRefs
3531 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3532 : rset->is_empty();
3533 }
3534
3535 bool is_typeArray_region(HeapRegion* region) const {
3536 return oop(region->bottom())->is_typeArray();
3537 }
3538
3539 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3540 assert(region->is_starts_humongous(), "Must start a humongous object");
3541
3542 // Candidate selection must satisfy the following constraints
3543 // while concurrent marking is in progress:
3544 //
3545 // * In order to maintain SATB invariants, an object must not be
3546 // reclaimed if it was allocated before the start of marking and
3547 // has not had its references scanned. Such an object must have
3548 // its references (including type metadata) scanned to ensure no
3549 // live objects are missed by the marking process. Objects
3550 // allocated after the start of concurrent marking don't need to
3551 // be scanned.
3552 //
3553 // * An object must not be reclaimed if it is on the concurrent
3554 // mark stack. Objects allocated after the start of concurrent
3555 // marking are never pushed on the mark stack.
3556 //
3557 // Nominating only objects allocated after the start of concurrent
3558 // marking is sufficient to meet both constraints. This may miss
3559 // some objects that satisfy the constraints, but the marking data
3560 // structures don't support efficiently performing the needed
3561 // additional tests or scrubbing of the mark stack.
3562 //
3563 // However, we presently only nominate is_typeArray() objects.
3564 // A humongous object containing references induces remembered
3565 // set entries on other regions. In order to reclaim such an
3566 // object, those remembered sets would need to be cleaned up.
3567 //
3568 // We also treat is_typeArray() objects specially, allowing them
3569 // to be reclaimed even if allocated before the start of
3570 // concurrent mark. For this we rely on mark stack insertion to
3571 // exclude is_typeArray() objects, preventing reclaiming an object
3572 // that is in the mark stack. We also rely on the metadata for
3573 // such objects to be built-in and so ensured to be kept live.
3574 // Frequent allocation and drop of large binary blobs is an
3575 // important use case for eager reclaim, and this special handling
3576 // may reduce needed headroom.
3577
3578 return is_typeArray_region(region) && is_remset_small(region);
3579 }
3580
3581 public:
3582 RegisterHumongousWithInCSetFastTestClosure()
3583 : _total_humongous(0),
3584 _candidate_humongous(0),
3585 _dcq(&JavaThread::dirty_card_queue_set()) {
3586 }
3587
3588 virtual bool doHeapRegion(HeapRegion* r) {
3589 if (!r->is_starts_humongous()) {
3590 return false;
3591 }
3592 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3593
3594 bool is_candidate = humongous_region_is_candidate(g1h, r);
3595 uint rindex = r->hrm_index();
3596 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3597 if (is_candidate) {
3598 _candidate_humongous++;
3599 g1h->register_humongous_region_with_cset(rindex);
3600 // Is_candidate already filters out humongous object with large remembered sets.
3601 // If we have a humongous object with a few remembered sets, we simply flush these
3602 // remembered set entries into the DCQS. That will result in automatic
3603 // re-evaluation of their remembered set entries during the following evacuation
3604 // phase.
3605 if (!r->rem_set()->is_empty()) {
3606 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3607 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3608 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3609 HeapRegionRemSetIterator hrrs(r->rem_set());
3610 size_t card_index;
3611 while (hrrs.has_next(card_index)) {
3612 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3613 // The remembered set might contain references to already freed
3614 // regions. Filter out such entries to avoid failing card table
3615 // verification.
3616 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3617 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3618 *card_ptr = CardTableModRefBS::dirty_card_val();
3619 _dcq.enqueue(card_ptr);
3620 }
3621 }
3622 }
3623 r->rem_set()->clear_locked();
3624 }
3625 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3626 }
3627 _total_humongous++;
3628
3629 return false;
3630 }
3631
3632 size_t total_humongous() const { return _total_humongous; }
3633 size_t candidate_humongous() const { return _candidate_humongous; }
3634
3635 void flush_rem_set_entries() { _dcq.flush(); }
3636 };
3637
3638 void G1CollectedHeap::register_humongous_regions_with_cset() {
3639 if (!G1EagerReclaimHumongousObjects) {
3640 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3641 return;
3642 }
3643 double time = os::elapsed_counter();
3644
3645 // Collect reclaim candidate information and register candidates with cset.
3646 RegisterHumongousWithInCSetFastTestClosure cl;
3647 heap_region_iterate(&cl);
3648
3649 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3650 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3651 cl.total_humongous(),
3652 cl.candidate_humongous());
3653 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3654
3655 // Finally flush all remembered set entries to re-check into the global DCQS.
3656 cl.flush_rem_set_entries();
3657 }
3658
3659 #ifdef ASSERT
3660 class VerifyCSetClosure: public HeapRegionClosure {
3661 public:
3662 bool doHeapRegion(HeapRegion* hr) {
3663 // Here we check that the CSet region's RSet is ready for parallel
3664 // iteration. The fields that we'll verify are only manipulated
3665 // when the region is part of a CSet and is collected. Afterwards,
3666 // we reset these fields when we clear the region's RSet (when the
3667 // region is freed) so they are ready when the region is
3668 // re-allocated. The only exception to this is if there's an
3669 // evacuation failure and instead of freeing the region we leave
3670 // it in the heap. In that case, we reset these fields during
3671 // evacuation failure handling.
3672 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3673
3674 // Here's a good place to add any other checks we'd like to
3675 // perform on CSet regions.
3676 return false;
3677 }
3678 };
3679 #endif // ASSERT
3680
3681 uint G1CollectedHeap::num_task_queues() const {
3682 return _task_queues->size();
3683 }
3684
3685 #if TASKQUEUE_STATS
3686 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3687 st->print_raw_cr("GC Task Stats");
3688 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3689 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3690 }
3691
3692 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3693 print_taskqueue_stats_hdr(st);
3694
3695 TaskQueueStats totals;
3696 const uint n = num_task_queues();
3697 for (uint i = 0; i < n; ++i) {
3698 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3699 totals += task_queue(i)->stats;
3700 }
3701 st->print_raw("tot "); totals.print(st); st->cr();
3702
3703 DEBUG_ONLY(totals.verify());
3704 }
3705
3706 void G1CollectedHeap::reset_taskqueue_stats() {
3707 const uint n = num_task_queues();
3708 for (uint i = 0; i < n; ++i) {
3709 task_queue(i)->stats.reset();
3710 }
3711 }
3712 #endif // TASKQUEUE_STATS
3713
3714 void G1CollectedHeap::log_gc_header() {
3715 if (!G1Log::fine()) {
3716 return;
3717 }
3718
3719 gclog_or_tty->gclog_stamp();
3720
3721 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3722 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3723 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3724
3725 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3726 }
3727
3728 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3729 if (!G1Log::fine()) {
3730 return;
3731 }
3732
3733 if (G1Log::finer()) {
3734 if (evacuation_failed()) {
3735 gclog_or_tty->print(" (to-space exhausted)");
3736 }
3737 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3738 g1_policy()->print_phases(pause_time_sec);
3739 g1_policy()->print_detailed_heap_transition();
3740 } else {
3741 if (evacuation_failed()) {
3742 gclog_or_tty->print("--");
3743 }
3744 g1_policy()->print_heap_transition();
3745 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3746 }
3747 gclog_or_tty->flush();
3748 }
3749
3750 void G1CollectedHeap::wait_for_root_region_scanning() {
3751 double scan_wait_start = os::elapsedTime();
3752 // We have to wait until the CM threads finish scanning the
3753 // root regions as it's the only way to ensure that all the
3754 // objects on them have been correctly scanned before we start
3755 // moving them during the GC.
3756 bool waited = _cm->root_regions()->wait_until_scan_finished();
3757 double wait_time_ms = 0.0;
3758 if (waited) {
3759 double scan_wait_end = os::elapsedTime();
3760 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3761 }
3762 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3763 }
3764
3765 bool
3766 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3767 assert_at_safepoint(true /* should_be_vm_thread */);
3768 guarantee(!is_gc_active(), "collection is not reentrant");
3769
3770 if (GC_locker::check_active_before_gc()) {
3771 return false;
3772 }
3773
3774 _gc_timer_stw->register_gc_start();
3775
3776 GCIdMark gc_id_mark;
3777 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3778
3779 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3780 ResourceMark rm;
3781
3782 wait_for_root_region_scanning();
3783
3784 G1Log::update_level();
3785 print_heap_before_gc();
3786 trace_heap_before_gc(_gc_tracer_stw);
3787
3788 verify_region_sets_optional();
3789 verify_dirty_young_regions();
3790
3791 // This call will decide whether this pause is an initial-mark
3792 // pause. If it is, during_initial_mark_pause() will return true
3793 // for the duration of this pause.
3794 g1_policy()->decide_on_conc_mark_initiation();
3795
3796 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3797 assert(!collector_state()->during_initial_mark_pause() ||
3798 collector_state()->gcs_are_young(), "sanity");
3799
3800 // We also do not allow mixed GCs during marking.
3801 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3802
3803 // Record whether this pause is an initial mark. When the current
3804 // thread has completed its logging output and it's safe to signal
3805 // the CM thread, the flag's value in the policy has been reset.
3806 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3807
3808 // Inner scope for scope based logging, timers, and stats collection
3809 {
3810 EvacuationInfo evacuation_info;
3811
3812 if (collector_state()->during_initial_mark_pause()) {
3813 // We are about to start a marking cycle, so we increment the
3814 // full collection counter.
3815 increment_old_marking_cycles_started();
3816 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3817 }
3818
3819 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3820
3821 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3822
3823 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3824 workers()->active_workers(),
3825 Threads::number_of_non_daemon_threads());
3826 workers()->set_active_workers(active_workers);
3827
3828 double pause_start_sec = os::elapsedTime();
3829 g1_policy()->note_gc_start(active_workers);
3830 log_gc_header();
3831
3832 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3833 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3834
3835 // If the secondary_free_list is not empty, append it to the
3836 // free_list. No need to wait for the cleanup operation to finish;
3837 // the region allocation code will check the secondary_free_list
3838 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3839 // set, skip this step so that the region allocation code has to
3840 // get entries from the secondary_free_list.
3841 if (!G1StressConcRegionFreeing) {
3842 append_secondary_free_list_if_not_empty_with_lock();
3843 }
3844
3845 assert(check_young_list_well_formed(), "young list should be well formed");
3846
3847 // Don't dynamically change the number of GC threads this early. A value of
3848 // 0 is used to indicate serial work. When parallel work is done,
3849 // it will be set.
3850
3851 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3852 IsGCActiveMark x;
3853
3854 gc_prologue(false);
3855 increment_total_collections(false /* full gc */);
3856 increment_gc_time_stamp();
3857
3858 verify_before_gc();
3859
3860 check_bitmaps("GC Start");
3861
3862 #if defined(COMPILER2) || INCLUDE_JVMCI
3863 DerivedPointerTable::clear();
3864 #endif
3865
3866 // Please see comment in g1CollectedHeap.hpp and
3867 // G1CollectedHeap::ref_processing_init() to see how
3868 // reference processing currently works in G1.
3869
3870 // Enable discovery in the STW reference processor
3871 ref_processor_stw()->enable_discovery();
3872
3873 {
3874 // We want to temporarily turn off discovery by the
3875 // CM ref processor, if necessary, and turn it back on
3876 // on again later if we do. Using a scoped
3877 // NoRefDiscovery object will do this.
3878 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3879
3880 // Forget the current alloc region (we might even choose it to be part
3881 // of the collection set!).
3882 _allocator->release_mutator_alloc_region();
3883
3884 // We should call this after we retire the mutator alloc
3885 // region(s) so that all the ALLOC / RETIRE events are generated
3886 // before the start GC event.
3887 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3888
3889 // This timing is only used by the ergonomics to handle our pause target.
3890 // It is unclear why this should not include the full pause. We will
3891 // investigate this in CR 7178365.
3892 //
3893 // Preserving the old comment here if that helps the investigation:
3894 //
3895 // The elapsed time induced by the start time below deliberately elides
3896 // the possible verification above.
3897 double sample_start_time_sec = os::elapsedTime();
3898
3899 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3900
3901 if (collector_state()->during_initial_mark_pause()) {
3902 concurrent_mark()->checkpointRootsInitialPre();
3903 }
3904
3905 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3906 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3907
3908 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3909
3910 register_humongous_regions_with_cset();
3911
3912 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3913
3914 _cm->note_start_of_gc();
3915 // We call this after finalize_cset() to
3916 // ensure that the CSet has been finalized.
3917 _cm->verify_no_cset_oops();
3918
3919 if (_hr_printer.is_active()) {
3920 HeapRegion* hr = g1_policy()->collection_set();
3921 while (hr != NULL) {
3922 _hr_printer.cset(hr);
3923 hr = hr->next_in_collection_set();
3924 }
3925 }
3926
3927 #ifdef ASSERT
3928 VerifyCSetClosure cl;
3929 collection_set_iterate(&cl);
3930 #endif // ASSERT
3931
3932 // Initialize the GC alloc regions.
3933 _allocator->init_gc_alloc_regions(evacuation_info);
3934
3935 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3936 pre_evacuate_collection_set();
3937
3938 // Actually do the work...
3939 evacuate_collection_set(evacuation_info, &per_thread_states);
3940
3941 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3942
3943 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3944 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3945
3946 eagerly_reclaim_humongous_regions();
3947
3948 g1_policy()->clear_collection_set();
3949
3950 // Start a new incremental collection set for the next pause.
3951 g1_policy()->start_incremental_cset_building();
3952
3953 clear_cset_fast_test();
3954
3955 _young_list->reset_sampled_info();
3956
3957 // Don't check the whole heap at this point as the
3958 // GC alloc regions from this pause have been tagged
3959 // as survivors and moved on to the survivor list.
3960 // Survivor regions will fail the !is_young() check.
3961 assert(check_young_list_empty(false /* check_heap */),
3962 "young list should be empty");
3963
3964 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3965 _young_list->first_survivor_region(),
3966 _young_list->last_survivor_region());
3967
3968 _young_list->reset_auxilary_lists();
3969
3970 if (evacuation_failed()) {
3971 set_used(recalculate_used());
3972 if (_archive_allocator != NULL) {
3973 _archive_allocator->clear_used();
3974 }
3975 for (uint i = 0; i < ParallelGCThreads; i++) {
3976 if (_evacuation_failed_info_array[i].has_failed()) {
3977 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3978 }
3979 }
3980 } else {
3981 // The "used" of the the collection set have already been subtracted
3982 // when they were freed. Add in the bytes evacuated.
3983 increase_used(g1_policy()->bytes_copied_during_gc());
3984 }
3985
3986 if (collector_state()->during_initial_mark_pause()) {
3987 // We have to do this before we notify the CM threads that
3988 // they can start working to make sure that all the
3989 // appropriate initialization is done on the CM object.
3990 concurrent_mark()->checkpointRootsInitialPost();
3991 collector_state()->set_mark_in_progress(true);
3992 // Note that we don't actually trigger the CM thread at
3993 // this point. We do that later when we're sure that
3994 // the current thread has completed its logging output.
3995 }
3996
3997 allocate_dummy_regions();
3998
3999 _allocator->init_mutator_alloc_region();
4000
4001 {
4002 size_t expand_bytes = g1_policy()->expansion_amount();
4003 if (expand_bytes > 0) {
4004 size_t bytes_before = capacity();
4005 // No need for an ergo verbose message here,
4006 // expansion_amount() does this when it returns a value > 0.
4007 double expand_ms;
4008 if (!expand(expand_bytes, &expand_ms)) {
4009 // We failed to expand the heap. Cannot do anything about it.
4010 }
4011 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
4012 }
4013 }
4014
4015 // We redo the verification but now wrt to the new CSet which
4016 // has just got initialized after the previous CSet was freed.
4017 _cm->verify_no_cset_oops();
4018 _cm->note_end_of_gc();
4019
4020 // This timing is only used by the ergonomics to handle our pause target.
4021 // It is unclear why this should not include the full pause. We will
4022 // investigate this in CR 7178365.
4023 double sample_end_time_sec = os::elapsedTime();
4024 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4025 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4026 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4027
4028 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4029 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4030
4031 MemoryService::track_memory_usage();
4032
4033 // In prepare_for_verify() below we'll need to scan the deferred
4034 // update buffers to bring the RSets up-to-date if
4035 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4036 // the update buffers we'll probably need to scan cards on the
4037 // regions we just allocated to (i.e., the GC alloc
4038 // regions). However, during the last GC we called
4039 // set_saved_mark() on all the GC alloc regions, so card
4040 // scanning might skip the [saved_mark_word()...top()] area of
4041 // those regions (i.e., the area we allocated objects into
4042 // during the last GC). But it shouldn't. Given that
4043 // saved_mark_word() is conditional on whether the GC time stamp
4044 // on the region is current or not, by incrementing the GC time
4045 // stamp here we invalidate all the GC time stamps on all the
4046 // regions and saved_mark_word() will simply return top() for
4047 // all the regions. This is a nicer way of ensuring this rather
4048 // than iterating over the regions and fixing them. In fact, the
4049 // GC time stamp increment here also ensures that
4050 // saved_mark_word() will return top() between pauses, i.e.,
4051 // during concurrent refinement. So we don't need the
4052 // is_gc_active() check to decided which top to use when
4053 // scanning cards (see CR 7039627).
4054 increment_gc_time_stamp();
4055
4056 verify_after_gc();
4057 check_bitmaps("GC End");
4058
4059 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4060 ref_processor_stw()->verify_no_references_recorded();
4061
4062 // CM reference discovery will be re-enabled if necessary.
4063 }
4064
4065 // We should do this after we potentially expand the heap so
4066 // that all the COMMIT events are generated before the end GC
4067 // event, and after we retire the GC alloc regions so that all
4068 // RETIRE events are generated before the end GC event.
4069 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4070
4071 #ifdef TRACESPINNING
4072 ParallelTaskTerminator::print_termination_counts();
4073 #endif
4074
4075 gc_epilogue(false);
4076 }
4077
4078 // Print the remainder of the GC log output.
4079 log_gc_footer(os::elapsedTime() - pause_start_sec);
4080
4081 // It is not yet to safe to tell the concurrent mark to
4082 // start as we have some optional output below. We don't want the
4083 // output from the concurrent mark thread interfering with this
4084 // logging output either.
4085
4086 _hrm.verify_optional();
4087 verify_region_sets_optional();
4088
4089 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4090 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4091
4092 print_heap_after_gc();
4093 trace_heap_after_gc(_gc_tracer_stw);
4094
4095 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4096 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4097 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4098 // before any GC notifications are raised.
4099 g1mm()->update_sizes();
4100
4101 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4102 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4103 _gc_timer_stw->register_gc_end();
4104 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4105 }
4106 // It should now be safe to tell the concurrent mark thread to start
4107 // without its logging output interfering with the logging output
4108 // that came from the pause.
4109
4110 if (should_start_conc_mark) {
4111 // CAUTION: after the doConcurrentMark() call below,
4112 // the concurrent marking thread(s) could be running
4113 // concurrently with us. Make sure that anything after
4114 // this point does not assume that we are the only GC thread
4115 // running. Note: of course, the actual marking work will
4116 // not start until the safepoint itself is released in
4117 // SuspendibleThreadSet::desynchronize().
4118 doConcurrentMark();
4119 }
4120
4121 return true;
4122 }
4123
4124 void G1CollectedHeap::remove_self_forwarding_pointers() {
4125 double remove_self_forwards_start = os::elapsedTime();
4126
4127 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4128 workers()->run_task(&rsfp_task);
4129
4130 // Now restore saved marks, if any.
4131 for (uint i = 0; i < ParallelGCThreads; i++) {
4132 OopAndMarkOopStack& cur = _preserved_objs[i];
4133 while (!cur.is_empty()) {
4134 OopAndMarkOop elem = cur.pop();
4135 elem.set_mark();
4136 }
4137 cur.clear(true);
4138 }
4139
4140 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4141 }
4142
4143 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4144 if (!_evacuation_failed) {
4145 _evacuation_failed = true;
4146 }
4147
4148 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4149
4150 // We want to call the "for_promotion_failure" version only in the
4151 // case of a promotion failure.
4152 if (m->must_be_preserved_for_promotion_failure(obj)) {
4153 OopAndMarkOop elem(obj, m);
4154 _preserved_objs[worker_id].push(elem);
4155 }
4156 }
4157
4158 class G1ParEvacuateFollowersClosure : public VoidClosure {
4159 private:
4160 double _start_term;
4161 double _term_time;
4162 size_t _term_attempts;
4163
4164 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4165 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4166 protected:
4167 G1CollectedHeap* _g1h;
4168 G1ParScanThreadState* _par_scan_state;
4169 RefToScanQueueSet* _queues;
4170 ParallelTaskTerminator* _terminator;
4171
4172 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4173 RefToScanQueueSet* queues() { return _queues; }
4174 ParallelTaskTerminator* terminator() { return _terminator; }
4175
4176 public:
4177 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4178 G1ParScanThreadState* par_scan_state,
4179 RefToScanQueueSet* queues,
4180 ParallelTaskTerminator* terminator)
4181 : _g1h(g1h), _par_scan_state(par_scan_state),
4182 _queues(queues), _terminator(terminator),
4183 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4184
4185 void do_void();
4186
4187 double term_time() const { return _term_time; }
4188 size_t term_attempts() const { return _term_attempts; }
4189
4190 private:
4191 inline bool offer_termination();
4192 };
4193
4194 bool G1ParEvacuateFollowersClosure::offer_termination() {
4195 G1ParScanThreadState* const pss = par_scan_state();
4196 start_term_time();
4197 const bool res = terminator()->offer_termination();
4198 end_term_time();
4199 return res;
4200 }
4201
4202 void G1ParEvacuateFollowersClosure::do_void() {
4203 G1ParScanThreadState* const pss = par_scan_state();
4204 pss->trim_queue();
4205 do {
4206 pss->steal_and_trim_queue(queues());
4207 } while (!offer_termination());
4208 }
4209
4210 class G1ParTask : public AbstractGangTask {
4211 protected:
4212 G1CollectedHeap* _g1h;
4213 G1ParScanThreadStateSet* _pss;
4214 RefToScanQueueSet* _queues;
4215 G1RootProcessor* _root_processor;
4216 ParallelTaskTerminator _terminator;
4217 uint _n_workers;
4218
4219 public:
4220 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4221 : AbstractGangTask("G1 collection"),
4222 _g1h(g1h),
4223 _pss(per_thread_states),
4224 _queues(task_queues),
4225 _root_processor(root_processor),
4226 _terminator(n_workers, _queues),
4227 _n_workers(n_workers)
4228 {}
4229
4230 void work(uint worker_id) {
4231 if (worker_id >= _n_workers) return; // no work needed this round
4232
4233 double start_sec = os::elapsedTime();
4234 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4235
4236 {
4237 ResourceMark rm;
4238 HandleMark hm;
4239
4240 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4241
4242 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4243 pss->set_ref_processor(rp);
4244
4245 double start_strong_roots_sec = os::elapsedTime();
4246
4247 _root_processor->evacuate_roots(pss->closures(), worker_id);
4248
4249 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4250
4251 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4252 // treating the nmethods visited to act as roots for concurrent marking.
4253 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4254 // objects copied by the current evacuation.
4255 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4256 pss->closures()->weak_codeblobs(),
4257 worker_id);
4258
4259 _pss->add_cards_scanned(worker_id, cards_scanned);
4260
4261 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4262
4263 double term_sec = 0.0;
4264 size_t evac_term_attempts = 0;
4265 {
4266 double start = os::elapsedTime();
4267 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4268 evac.do_void();
4269
4270 evac_term_attempts = evac.term_attempts();
4271 term_sec = evac.term_time();
4272 double elapsed_sec = os::elapsedTime() - start;
4273 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4274 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4275 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4276 }
4277
4278 assert(pss->queue_is_empty(), "should be empty");
4279
4280 if (PrintTerminationStats) {
4281 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4282 size_t lab_waste;
4283 size_t lab_undo_waste;
4284 pss->waste(lab_waste, lab_undo_waste);
4285 _g1h->print_termination_stats(gclog_or_tty,
4286 worker_id,
4287 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4288 strong_roots_sec * 1000.0, /* strong roots time */
4289 term_sec * 1000.0, /* evac term time */
4290 evac_term_attempts, /* evac term attempts */
4291 lab_waste, /* alloc buffer waste */
4292 lab_undo_waste /* undo waste */
4293 );
4294 }
4295
4296 // Close the inner scope so that the ResourceMark and HandleMark
4297 // destructors are executed here and are included as part of the
4298 // "GC Worker Time".
4299 }
4300 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4301 }
4302 };
4303
4304 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4305 st->print_raw_cr("GC Termination Stats");
4306 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4307 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4308 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4309 }
4310
4311 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4312 uint worker_id,
4313 double elapsed_ms,
4314 double strong_roots_ms,
4315 double term_ms,
4316 size_t term_attempts,
4317 size_t alloc_buffer_waste,
4318 size_t undo_waste) const {
4319 st->print_cr("%3d %9.2f %9.2f %6.2f "
4320 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4321 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4322 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4323 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4324 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4325 alloc_buffer_waste * HeapWordSize / K,
4326 undo_waste * HeapWordSize / K);
4327 }
4328
4329 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4330 private:
4331 BoolObjectClosure* _is_alive;
4332 int _initial_string_table_size;
4333 int _initial_symbol_table_size;
4334
4335 bool _process_strings;
4336 int _strings_processed;
4337 int _strings_removed;
4338
4339 bool _process_symbols;
4340 int _symbols_processed;
4341 int _symbols_removed;
4342
4343 public:
4344 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4345 AbstractGangTask("String/Symbol Unlinking"),
4346 _is_alive(is_alive),
4347 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4348 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4349
4350 _initial_string_table_size = StringTable::the_table()->table_size();
4351 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4352 if (process_strings) {
4353 StringTable::clear_parallel_claimed_index();
4354 }
4355 if (process_symbols) {
4356 SymbolTable::clear_parallel_claimed_index();
4357 }
4358 }
4359
4360 ~G1StringSymbolTableUnlinkTask() {
4361 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4362 "claim value %d after unlink less than initial string table size %d",
4363 StringTable::parallel_claimed_index(), _initial_string_table_size);
4364 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4365 "claim value %d after unlink less than initial symbol table size %d",
4366 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4367
4368 if (G1TraceStringSymbolTableScrubbing) {
4369 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4370 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4371 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4372 strings_processed(), strings_removed(),
4373 symbols_processed(), symbols_removed());
4374 }
4375 }
4376
4377 void work(uint worker_id) {
4378 int strings_processed = 0;
4379 int strings_removed = 0;
4380 int symbols_processed = 0;
4381 int symbols_removed = 0;
4382 if (_process_strings) {
4383 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4384 Atomic::add(strings_processed, &_strings_processed);
4385 Atomic::add(strings_removed, &_strings_removed);
4386 }
4387 if (_process_symbols) {
4388 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4389 Atomic::add(symbols_processed, &_symbols_processed);
4390 Atomic::add(symbols_removed, &_symbols_removed);
4391 }
4392 }
4393
4394 size_t strings_processed() const { return (size_t)_strings_processed; }
4395 size_t strings_removed() const { return (size_t)_strings_removed; }
4396
4397 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4398 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4399 };
4400
4401 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4402 private:
4403 static Monitor* _lock;
4404
4405 BoolObjectClosure* const _is_alive;
4406 const bool _unloading_occurred;
4407 const uint _num_workers;
4408
4409 // Variables used to claim nmethods.
4410 nmethod* _first_nmethod;
4411 volatile nmethod* _claimed_nmethod;
4412
4413 // The list of nmethods that need to be processed by the second pass.
4414 volatile nmethod* _postponed_list;
4415 volatile uint _num_entered_barrier;
4416
4417 public:
4418 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4419 _is_alive(is_alive),
4420 _unloading_occurred(unloading_occurred),
4421 _num_workers(num_workers),
4422 _first_nmethod(NULL),
4423 _claimed_nmethod(NULL),
4424 _postponed_list(NULL),
4425 _num_entered_barrier(0)
4426 {
4427 nmethod::increase_unloading_clock();
4428 // Get first alive nmethod
4429 NMethodIterator iter = NMethodIterator();
4430 if(iter.next_alive()) {
4431 _first_nmethod = iter.method();
4432 }
4433 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4434 }
4435
4436 ~G1CodeCacheUnloadingTask() {
4437 CodeCache::verify_clean_inline_caches();
4438
4439 CodeCache::set_needs_cache_clean(false);
4440 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4441
4442 CodeCache::verify_icholder_relocations();
4443 }
4444
4445 private:
4446 void add_to_postponed_list(nmethod* nm) {
4447 nmethod* old;
4448 do {
4449 old = (nmethod*)_postponed_list;
4450 nm->set_unloading_next(old);
4451 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4452 }
4453
4454 void clean_nmethod(nmethod* nm) {
4455 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4456
4457 if (postponed) {
4458 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4459 add_to_postponed_list(nm);
4460 }
4461
4462 // Mark that this thread has been cleaned/unloaded.
4463 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4464 nm->set_unloading_clock(nmethod::global_unloading_clock());
4465 }
4466
4467 void clean_nmethod_postponed(nmethod* nm) {
4468 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4469 }
4470
4471 static const int MaxClaimNmethods = 16;
4472
4473 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4474 nmethod* first;
4475 NMethodIterator last;
4476
4477 do {
4478 *num_claimed_nmethods = 0;
4479
4480 first = (nmethod*)_claimed_nmethod;
4481 last = NMethodIterator(first);
4482
4483 if (first != NULL) {
4484
4485 for (int i = 0; i < MaxClaimNmethods; i++) {
4486 if (!last.next_alive()) {
4487 break;
4488 }
4489 claimed_nmethods[i] = last.method();
4490 (*num_claimed_nmethods)++;
4491 }
4492 }
4493
4494 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4495 }
4496
4497 nmethod* claim_postponed_nmethod() {
4498 nmethod* claim;
4499 nmethod* next;
4500
4501 do {
4502 claim = (nmethod*)_postponed_list;
4503 if (claim == NULL) {
4504 return NULL;
4505 }
4506
4507 next = claim->unloading_next();
4508
4509 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4510
4511 return claim;
4512 }
4513
4514 public:
4515 // Mark that we're done with the first pass of nmethod cleaning.
4516 void barrier_mark(uint worker_id) {
4517 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4518 _num_entered_barrier++;
4519 if (_num_entered_barrier == _num_workers) {
4520 ml.notify_all();
4521 }
4522 }
4523
4524 // See if we have to wait for the other workers to
4525 // finish their first-pass nmethod cleaning work.
4526 void barrier_wait(uint worker_id) {
4527 if (_num_entered_barrier < _num_workers) {
4528 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4529 while (_num_entered_barrier < _num_workers) {
4530 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4531 }
4532 }
4533 }
4534
4535 // Cleaning and unloading of nmethods. Some work has to be postponed
4536 // to the second pass, when we know which nmethods survive.
4537 void work_first_pass(uint worker_id) {
4538 // The first nmethods is claimed by the first worker.
4539 if (worker_id == 0 && _first_nmethod != NULL) {
4540 clean_nmethod(_first_nmethod);
4541 _first_nmethod = NULL;
4542 }
4543
4544 int num_claimed_nmethods;
4545 nmethod* claimed_nmethods[MaxClaimNmethods];
4546
4547 while (true) {
4548 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4549
4550 if (num_claimed_nmethods == 0) {
4551 break;
4552 }
4553
4554 for (int i = 0; i < num_claimed_nmethods; i++) {
4555 clean_nmethod(claimed_nmethods[i]);
4556 }
4557 }
4558 }
4559
4560 void work_second_pass(uint worker_id) {
4561 nmethod* nm;
4562 // Take care of postponed nmethods.
4563 while ((nm = claim_postponed_nmethod()) != NULL) {
4564 clean_nmethod_postponed(nm);
4565 }
4566 }
4567 };
4568
4569 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4570
4571 class G1KlassCleaningTask : public StackObj {
4572 BoolObjectClosure* _is_alive;
4573 volatile jint _clean_klass_tree_claimed;
4574 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4575
4576 public:
4577 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4578 _is_alive(is_alive),
4579 _clean_klass_tree_claimed(0),
4580 _klass_iterator() {
4581 }
4582
4583 private:
4584 bool claim_clean_klass_tree_task() {
4585 if (_clean_klass_tree_claimed) {
4586 return false;
4587 }
4588
4589 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4590 }
4591
4592 InstanceKlass* claim_next_klass() {
4593 Klass* klass;
4594 do {
4595 klass =_klass_iterator.next_klass();
4596 } while (klass != NULL && !klass->is_instance_klass());
4597
4598 // this can be null so don't call InstanceKlass::cast
4599 return static_cast<InstanceKlass*>(klass);
4600 }
4601
4602 public:
4603
4604 void clean_klass(InstanceKlass* ik) {
4605 ik->clean_weak_instanceklass_links(_is_alive);
4606 }
4607
4608 void work() {
4609 ResourceMark rm;
4610
4611 // One worker will clean the subklass/sibling klass tree.
4612 if (claim_clean_klass_tree_task()) {
4613 Klass::clean_subklass_tree(_is_alive);
4614 }
4615
4616 // All workers will help cleaning the classes,
4617 InstanceKlass* klass;
4618 while ((klass = claim_next_klass()) != NULL) {
4619 clean_klass(klass);
4620 }
4621 }
4622 };
4623
4624 // To minimize the remark pause times, the tasks below are done in parallel.
4625 class G1ParallelCleaningTask : public AbstractGangTask {
4626 private:
4627 G1StringSymbolTableUnlinkTask _string_symbol_task;
4628 G1CodeCacheUnloadingTask _code_cache_task;
4629 G1KlassCleaningTask _klass_cleaning_task;
4630
4631 public:
4632 // The constructor is run in the VMThread.
4633 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4634 AbstractGangTask("Parallel Cleaning"),
4635 _string_symbol_task(is_alive, process_strings, process_symbols),
4636 _code_cache_task(num_workers, is_alive, unloading_occurred),
4637 _klass_cleaning_task(is_alive) {
4638 }
4639
4640 // The parallel work done by all worker threads.
4641 void work(uint worker_id) {
4642 // Do first pass of code cache cleaning.
4643 _code_cache_task.work_first_pass(worker_id);
4644
4645 // Let the threads mark that the first pass is done.
4646 _code_cache_task.barrier_mark(worker_id);
4647
4648 // Clean the Strings and Symbols.
4649 _string_symbol_task.work(worker_id);
4650
4651 // Wait for all workers to finish the first code cache cleaning pass.
4652 _code_cache_task.barrier_wait(worker_id);
4653
4654 // Do the second code cache cleaning work, which realize on
4655 // the liveness information gathered during the first pass.
4656 _code_cache_task.work_second_pass(worker_id);
4657
4658 // Clean all klasses that were not unloaded.
4659 _klass_cleaning_task.work();
4660 }
4661 };
4662
4663
4664 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4665 bool process_strings,
4666 bool process_symbols,
4667 bool class_unloading_occurred) {
4668 uint n_workers = workers()->active_workers();
4669
4670 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4671 n_workers, class_unloading_occurred);
4672 workers()->run_task(&g1_unlink_task);
4673 }
4674
4675 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4676 bool process_strings, bool process_symbols) {
4677 {
4678 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4679 workers()->run_task(&g1_unlink_task);
4680 }
4681
4682 if (G1StringDedup::is_enabled()) {
4683 G1StringDedup::unlink(is_alive);
4684 }
4685 }
4686
4687 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4688 private:
4689 DirtyCardQueueSet* _queue;
4690 public:
4691 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4692
4693 virtual void work(uint worker_id) {
4694 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4695 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4696
4697 RedirtyLoggedCardTableEntryClosure cl;
4698 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4699
4700 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4701 }
4702 };
4703
4704 void G1CollectedHeap::redirty_logged_cards() {
4705 double redirty_logged_cards_start = os::elapsedTime();
4706
4707 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4708 dirty_card_queue_set().reset_for_par_iteration();
4709 workers()->run_task(&redirty_task);
4710
4711 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4712 dcq.merge_bufferlists(&dirty_card_queue_set());
4713 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4714
4715 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4716 }
4717
4718 // Weak Reference Processing support
4719
4720 // An always "is_alive" closure that is used to preserve referents.
4721 // If the object is non-null then it's alive. Used in the preservation
4722 // of referent objects that are pointed to by reference objects
4723 // discovered by the CM ref processor.
4724 class G1AlwaysAliveClosure: public BoolObjectClosure {
4725 G1CollectedHeap* _g1;
4726 public:
4727 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4728 bool do_object_b(oop p) {
4729 if (p != NULL) {
4730 return true;
4731 }
4732 return false;
4733 }
4734 };
4735
4736 bool G1STWIsAliveClosure::do_object_b(oop p) {
4737 // An object is reachable if it is outside the collection set,
4738 // or is inside and copied.
4739 return !_g1->is_in_cset(p) || p->is_forwarded();
4740 }
4741
4742 // Non Copying Keep Alive closure
4743 class G1KeepAliveClosure: public OopClosure {
4744 G1CollectedHeap* _g1;
4745 public:
4746 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4747 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4748 void do_oop(oop* p) {
4749 oop obj = *p;
4750 assert(obj != NULL, "the caller should have filtered out NULL values");
4751
4752 const InCSetState cset_state = _g1->in_cset_state(obj);
4753 if (!cset_state.is_in_cset_or_humongous()) {
4754 return;
4755 }
4756 if (cset_state.is_in_cset()) {
4757 assert( obj->is_forwarded(), "invariant" );
4758 *p = obj->forwardee();
4759 } else {
4760 assert(!obj->is_forwarded(), "invariant" );
4761 assert(cset_state.is_humongous(),
4762 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4763 _g1->set_humongous_is_live(obj);
4764 }
4765 }
4766 };
4767
4768 // Copying Keep Alive closure - can be called from both
4769 // serial and parallel code as long as different worker
4770 // threads utilize different G1ParScanThreadState instances
4771 // and different queues.
4772
4773 class G1CopyingKeepAliveClosure: public OopClosure {
4774 G1CollectedHeap* _g1h;
4775 OopClosure* _copy_non_heap_obj_cl;
4776 G1ParScanThreadState* _par_scan_state;
4777
4778 public:
4779 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4780 OopClosure* non_heap_obj_cl,
4781 G1ParScanThreadState* pss):
4782 _g1h(g1h),
4783 _copy_non_heap_obj_cl(non_heap_obj_cl),
4784 _par_scan_state(pss)
4785 {}
4786
4787 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4788 virtual void do_oop( oop* p) { do_oop_work(p); }
4789
4790 template <class T> void do_oop_work(T* p) {
4791 oop obj = oopDesc::load_decode_heap_oop(p);
4792
4793 if (_g1h->is_in_cset_or_humongous(obj)) {
4794 // If the referent object has been forwarded (either copied
4795 // to a new location or to itself in the event of an
4796 // evacuation failure) then we need to update the reference
4797 // field and, if both reference and referent are in the G1
4798 // heap, update the RSet for the referent.
4799 //
4800 // If the referent has not been forwarded then we have to keep
4801 // it alive by policy. Therefore we have copy the referent.
4802 //
4803 // If the reference field is in the G1 heap then we can push
4804 // on the PSS queue. When the queue is drained (after each
4805 // phase of reference processing) the object and it's followers
4806 // will be copied, the reference field set to point to the
4807 // new location, and the RSet updated. Otherwise we need to
4808 // use the the non-heap or metadata closures directly to copy
4809 // the referent object and update the pointer, while avoiding
4810 // updating the RSet.
4811
4812 if (_g1h->is_in_g1_reserved(p)) {
4813 _par_scan_state->push_on_queue(p);
4814 } else {
4815 assert(!Metaspace::contains((const void*)p),
4816 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4817 _copy_non_heap_obj_cl->do_oop(p);
4818 }
4819 }
4820 }
4821 };
4822
4823 // Serial drain queue closure. Called as the 'complete_gc'
4824 // closure for each discovered list in some of the
4825 // reference processing phases.
4826
4827 class G1STWDrainQueueClosure: public VoidClosure {
4828 protected:
4829 G1CollectedHeap* _g1h;
4830 G1ParScanThreadState* _par_scan_state;
4831
4832 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4833
4834 public:
4835 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4836 _g1h(g1h),
4837 _par_scan_state(pss)
4838 { }
4839
4840 void do_void() {
4841 G1ParScanThreadState* const pss = par_scan_state();
4842 pss->trim_queue();
4843 }
4844 };
4845
4846 // Parallel Reference Processing closures
4847
4848 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4849 // processing during G1 evacuation pauses.
4850
4851 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4852 private:
4853 G1CollectedHeap* _g1h;
4854 G1ParScanThreadStateSet* _pss;
4855 RefToScanQueueSet* _queues;
4856 WorkGang* _workers;
4857 uint _active_workers;
4858
4859 public:
4860 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4861 G1ParScanThreadStateSet* per_thread_states,
4862 WorkGang* workers,
4863 RefToScanQueueSet *task_queues,
4864 uint n_workers) :
4865 _g1h(g1h),
4866 _pss(per_thread_states),
4867 _queues(task_queues),
4868 _workers(workers),
4869 _active_workers(n_workers)
4870 {
4871 assert(n_workers > 0, "shouldn't call this otherwise");
4872 }
4873
4874 // Executes the given task using concurrent marking worker threads.
4875 virtual void execute(ProcessTask& task);
4876 virtual void execute(EnqueueTask& task);
4877 };
4878
4879 // Gang task for possibly parallel reference processing
4880
4881 class G1STWRefProcTaskProxy: public AbstractGangTask {
4882 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4883 ProcessTask& _proc_task;
4884 G1CollectedHeap* _g1h;
4885 G1ParScanThreadStateSet* _pss;
4886 RefToScanQueueSet* _task_queues;
4887 ParallelTaskTerminator* _terminator;
4888
4889 public:
4890 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4891 G1CollectedHeap* g1h,
4892 G1ParScanThreadStateSet* per_thread_states,
4893 RefToScanQueueSet *task_queues,
4894 ParallelTaskTerminator* terminator) :
4895 AbstractGangTask("Process reference objects in parallel"),
4896 _proc_task(proc_task),
4897 _g1h(g1h),
4898 _pss(per_thread_states),
4899 _task_queues(task_queues),
4900 _terminator(terminator)
4901 {}
4902
4903 virtual void work(uint worker_id) {
4904 // The reference processing task executed by a single worker.
4905 ResourceMark rm;
4906 HandleMark hm;
4907
4908 G1STWIsAliveClosure is_alive(_g1h);
4909
4910 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4911 pss->set_ref_processor(NULL);
4912
4913 // Keep alive closure.
4914 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4915
4916 // Complete GC closure
4917 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4918
4919 // Call the reference processing task's work routine.
4920 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4921
4922 // Note we cannot assert that the refs array is empty here as not all
4923 // of the processing tasks (specifically phase2 - pp2_work) execute
4924 // the complete_gc closure (which ordinarily would drain the queue) so
4925 // the queue may not be empty.
4926 }
4927 };
4928
4929 // Driver routine for parallel reference processing.
4930 // Creates an instance of the ref processing gang
4931 // task and has the worker threads execute it.
4932 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4933 assert(_workers != NULL, "Need parallel worker threads.");
4934
4935 ParallelTaskTerminator terminator(_active_workers, _queues);
4936 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4937
4938 _workers->run_task(&proc_task_proxy);
4939 }
4940
4941 // Gang task for parallel reference enqueueing.
4942
4943 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4944 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4945 EnqueueTask& _enq_task;
4946
4947 public:
4948 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4949 AbstractGangTask("Enqueue reference objects in parallel"),
4950 _enq_task(enq_task)
4951 { }
4952
4953 virtual void work(uint worker_id) {
4954 _enq_task.work(worker_id);
4955 }
4956 };
4957
4958 // Driver routine for parallel reference enqueueing.
4959 // Creates an instance of the ref enqueueing gang
4960 // task and has the worker threads execute it.
4961
4962 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4963 assert(_workers != NULL, "Need parallel worker threads.");
4964
4965 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4966
4967 _workers->run_task(&enq_task_proxy);
4968 }
4969
4970 // End of weak reference support closures
4971
4972 // Abstract task used to preserve (i.e. copy) any referent objects
4973 // that are in the collection set and are pointed to by reference
4974 // objects discovered by the CM ref processor.
4975
4976 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4977 protected:
4978 G1CollectedHeap* _g1h;
4979 G1ParScanThreadStateSet* _pss;
4980 RefToScanQueueSet* _queues;
4981 ParallelTaskTerminator _terminator;
4982 uint _n_workers;
4983
4984 public:
4985 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4986 AbstractGangTask("ParPreserveCMReferents"),
4987 _g1h(g1h),
4988 _pss(per_thread_states),
4989 _queues(task_queues),
4990 _terminator(workers, _queues),
4991 _n_workers(workers)
4992 { }
4993
4994 void work(uint worker_id) {
4995 ResourceMark rm;
4996 HandleMark hm;
4997
4998 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4999 pss->set_ref_processor(NULL);
5000 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5001
5002 // Is alive closure
5003 G1AlwaysAliveClosure always_alive(_g1h);
5004
5005 // Copying keep alive closure. Applied to referent objects that need
5006 // to be copied.
5007 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
5008
5009 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5010
5011 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5012 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5013
5014 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5015 // So this must be true - but assert just in case someone decides to
5016 // change the worker ids.
5017 assert(worker_id < limit, "sanity");
5018 assert(!rp->discovery_is_atomic(), "check this code");
5019
5020 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5021 for (uint idx = worker_id; idx < limit; idx += stride) {
5022 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5023
5024 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5025 while (iter.has_next()) {
5026 // Since discovery is not atomic for the CM ref processor, we
5027 // can see some null referent objects.
5028 iter.load_ptrs(DEBUG_ONLY(true));
5029 oop ref = iter.obj();
5030
5031 // This will filter nulls.
5032 if (iter.is_referent_alive()) {
5033 iter.make_referent_alive();
5034 }
5035 iter.move_to_next();
5036 }
5037 }
5038
5039 // Drain the queue - which may cause stealing
5040 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5041 drain_queue.do_void();
5042 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5043 assert(pss->queue_is_empty(), "should be");
5044 }
5045 };
5046
5047 // Weak Reference processing during an evacuation pause (part 1).
5048 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5049 double ref_proc_start = os::elapsedTime();
5050
5051 ReferenceProcessor* rp = _ref_processor_stw;
5052 assert(rp->discovery_enabled(), "should have been enabled");
5053
5054 // Any reference objects, in the collection set, that were 'discovered'
5055 // by the CM ref processor should have already been copied (either by
5056 // applying the external root copy closure to the discovered lists, or
5057 // by following an RSet entry).
5058 //
5059 // But some of the referents, that are in the collection set, that these
5060 // reference objects point to may not have been copied: the STW ref
5061 // processor would have seen that the reference object had already
5062 // been 'discovered' and would have skipped discovering the reference,
5063 // but would not have treated the reference object as a regular oop.
5064 // As a result the copy closure would not have been applied to the
5065 // referent object.
5066 //
5067 // We need to explicitly copy these referent objects - the references
5068 // will be processed at the end of remarking.
5069 //
5070 // We also need to do this copying before we process the reference
5071 // objects discovered by the STW ref processor in case one of these
5072 // referents points to another object which is also referenced by an
5073 // object discovered by the STW ref processor.
5074
5075 uint no_of_gc_workers = workers()->active_workers();
5076
5077 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5078 per_thread_states,
5079 no_of_gc_workers,
5080 _task_queues);
5081
5082 workers()->run_task(&keep_cm_referents);
5083
5084 // Closure to test whether a referent is alive.
5085 G1STWIsAliveClosure is_alive(this);
5086
5087 // Even when parallel reference processing is enabled, the processing
5088 // of JNI refs is serial and performed serially by the current thread
5089 // rather than by a worker. The following PSS will be used for processing
5090 // JNI refs.
5091
5092 // Use only a single queue for this PSS.
5093 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5094 pss->set_ref_processor(NULL);
5095 assert(pss->queue_is_empty(), "pre-condition");
5096
5097 // Keep alive closure.
5098 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5099
5100 // Serial Complete GC closure
5101 G1STWDrainQueueClosure drain_queue(this, pss);
5102
5103 // Setup the soft refs policy...
5104 rp->setup_policy(false);
5105
5106 ReferenceProcessorStats stats;
5107 if (!rp->processing_is_mt()) {
5108 // Serial reference processing...
5109 stats = rp->process_discovered_references(&is_alive,
5110 &keep_alive,
5111 &drain_queue,
5112 NULL,
5113 _gc_timer_stw);
5114 } else {
5115 // Parallel reference processing
5116 assert(rp->num_q() == no_of_gc_workers, "sanity");
5117 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5118
5119 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5120 stats = rp->process_discovered_references(&is_alive,
5121 &keep_alive,
5122 &drain_queue,
5123 &par_task_executor,
5124 _gc_timer_stw);
5125 }
5126
5127 _gc_tracer_stw->report_gc_reference_stats(stats);
5128
5129 // We have completed copying any necessary live referent objects.
5130 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5131
5132 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5133 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5134 }
5135
5136 // Weak Reference processing during an evacuation pause (part 2).
5137 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5138 double ref_enq_start = os::elapsedTime();
5139
5140 ReferenceProcessor* rp = _ref_processor_stw;
5141 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5142
5143 // Now enqueue any remaining on the discovered lists on to
5144 // the pending list.
5145 if (!rp->processing_is_mt()) {
5146 // Serial reference processing...
5147 rp->enqueue_discovered_references();
5148 } else {
5149 // Parallel reference enqueueing
5150
5151 uint n_workers = workers()->active_workers();
5152
5153 assert(rp->num_q() == n_workers, "sanity");
5154 assert(n_workers <= rp->max_num_q(), "sanity");
5155
5156 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5157 rp->enqueue_discovered_references(&par_task_executor);
5158 }
5159
5160 rp->verify_no_references_recorded();
5161 assert(!rp->discovery_enabled(), "should have been disabled");
5162
5163 // FIXME
5164 // CM's reference processing also cleans up the string and symbol tables.
5165 // Should we do that here also? We could, but it is a serial operation
5166 // and could significantly increase the pause time.
5167
5168 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5169 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5170 }
5171
5172 void G1CollectedHeap::pre_evacuate_collection_set() {
5173 _expand_heap_after_alloc_failure = true;
5174 _evacuation_failed = false;
5175
5176 // Disable the hot card cache.
5177 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5178 hot_card_cache->reset_hot_cache_claimed_index();
5179 hot_card_cache->set_use_cache(false);
5180
5181 }
5182
5183 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5184 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5185
5186 // Should G1EvacuationFailureALot be in effect for this GC?
5187 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5188
5189 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5190 double start_par_time_sec = os::elapsedTime();
5191 double end_par_time_sec;
5192
5193 {
5194 const uint n_workers = workers()->active_workers();
5195 G1RootProcessor root_processor(this, n_workers);
5196 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5197 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5198 if (collector_state()->during_initial_mark_pause()) {
5199 ClassLoaderDataGraph::clear_claimed_marks();
5200 }
5201
5202 // The individual threads will set their evac-failure closures.
5203 if (PrintTerminationStats) {
5204 print_termination_stats_hdr(gclog_or_tty);
5205 }
5206
5207 workers()->run_task(&g1_par_task);
5208 end_par_time_sec = os::elapsedTime();
5209
5210 // Closing the inner scope will execute the destructor
5211 // for the G1RootProcessor object. We record the current
5212 // elapsed time before closing the scope so that time
5213 // taken for the destructor is NOT included in the
5214 // reported parallel time.
5215 }
5216
5217 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5218
5219 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5220 phase_times->record_par_time(par_time_ms);
5221
5222 double code_root_fixup_time_ms =
5223 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5224 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5225
5226 // Process any discovered reference objects - we have
5227 // to do this _before_ we retire the GC alloc regions
5228 // as we may have to copy some 'reachable' referent
5229 // objects (and their reachable sub-graphs) that were
5230 // not copied during the pause.
5231 process_discovered_references(per_thread_states);
5232
5233 if (G1StringDedup::is_enabled()) {
5234 double fixup_start = os::elapsedTime();
5235
5236 G1STWIsAliveClosure is_alive(this);
5237 G1KeepAliveClosure keep_alive(this);
5238 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5239
5240 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5241 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5242 }
5243
5244 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5245
5246 if (evacuation_failed()) {
5247 remove_self_forwarding_pointers();
5248
5249 // Reset the G1EvacuationFailureALot counters and flags
5250 // Note: the values are reset only when an actual
5251 // evacuation failure occurs.
5252 NOT_PRODUCT(reset_evacuation_should_fail();)
5253 }
5254
5255 // Enqueue any remaining references remaining on the STW
5256 // reference processor's discovered lists. We need to do
5257 // this after the card table is cleaned (and verified) as
5258 // the act of enqueueing entries on to the pending list
5259 // will log these updates (and dirty their associated
5260 // cards). We need these updates logged to update any
5261 // RSets.
5262 enqueue_discovered_references(per_thread_states);
5263 }
5264
5265 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5266 _allocator->release_gc_alloc_regions(evacuation_info);
5267
5268 per_thread_states->flush();
5269
5270 record_obj_copy_mem_stats();
5271
5272 // Reset and re-enable the hot card cache.
5273 // Note the counts for the cards in the regions in the
5274 // collection set are reset when the collection set is freed.
5275 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5276 hot_card_cache->reset_hot_cache();
5277 hot_card_cache->set_use_cache(true);
5278
5279 purge_code_root_memory();
5280
5281 redirty_logged_cards();
5282 #if defined(COMPILER2) || INCLUDE_JVMCI
5283 DerivedPointerTable::update_pointers();
5284 #endif
5285 }
5286
5287 void G1CollectedHeap::record_obj_copy_mem_stats() {
5288 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5289 create_g1_evac_summary(&_old_evac_stats));
5290 }
5291
5292 void G1CollectedHeap::free_region(HeapRegion* hr,
5293 FreeRegionList* free_list,
5294 bool par,
5295 bool locked) {
5296 assert(!hr->is_free(), "the region should not be free");
5297 assert(!hr->is_empty(), "the region should not be empty");
5298 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5299 assert(free_list != NULL, "pre-condition");
5300
5301 if (G1VerifyBitmaps) {
5302 MemRegion mr(hr->bottom(), hr->end());
5303 concurrent_mark()->clearRangePrevBitmap(mr);
5304 }
5305
5306 // Clear the card counts for this region.
5307 // Note: we only need to do this if the region is not young
5308 // (since we don't refine cards in young regions).
5309 if (!hr->is_young()) {
5310 _cg1r->hot_card_cache()->reset_card_counts(hr);
5311 }
5312 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5313 free_list->add_ordered(hr);
5314 }
5315
5316 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5317 FreeRegionList* free_list,
5318 bool par) {
5319 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5320 assert(free_list != NULL, "pre-condition");
5321
5322 size_t hr_capacity = hr->capacity();
5323 // We need to read this before we make the region non-humongous,
5324 // otherwise the information will be gone.
5325 uint last_index = hr->last_hc_index();
5326 hr->clear_humongous();
5327 free_region(hr, free_list, par);
5328
5329 uint i = hr->hrm_index() + 1;
5330 while (i < last_index) {
5331 HeapRegion* curr_hr = region_at(i);
5332 assert(curr_hr->is_continues_humongous(), "invariant");
5333 curr_hr->clear_humongous();
5334 free_region(curr_hr, free_list, par);
5335 i += 1;
5336 }
5337 }
5338
5339 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5340 const HeapRegionSetCount& humongous_regions_removed) {
5341 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5342 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5343 _old_set.bulk_remove(old_regions_removed);
5344 _humongous_set.bulk_remove(humongous_regions_removed);
5345 }
5346
5347 }
5348
5349 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5350 assert(list != NULL, "list can't be null");
5351 if (!list->is_empty()) {
5352 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5353 _hrm.insert_list_into_free_list(list);
5354 }
5355 }
5356
5357 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5358 decrease_used(bytes);
5359 }
5360
5361 class G1ParCleanupCTTask : public AbstractGangTask {
5362 G1SATBCardTableModRefBS* _ct_bs;
5363 G1CollectedHeap* _g1h;
5364 HeapRegion* volatile _su_head;
5365 public:
5366 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5367 G1CollectedHeap* g1h) :
5368 AbstractGangTask("G1 Par Cleanup CT Task"),
5369 _ct_bs(ct_bs), _g1h(g1h) { }
5370
5371 void work(uint worker_id) {
5372 HeapRegion* r;
5373 while (r = _g1h->pop_dirty_cards_region()) {
5374 clear_cards(r);
5375 }
5376 }
5377
5378 void clear_cards(HeapRegion* r) {
5379 // Cards of the survivors should have already been dirtied.
5380 if (!r->is_survivor()) {
5381 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5382 }
5383 }
5384 };
5385
5386 #ifndef PRODUCT
5387 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5388 G1CollectedHeap* _g1h;
5389 G1SATBCardTableModRefBS* _ct_bs;
5390 public:
5391 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5392 : _g1h(g1h), _ct_bs(ct_bs) { }
5393 virtual bool doHeapRegion(HeapRegion* r) {
5394 if (r->is_survivor()) {
5395 _g1h->verify_dirty_region(r);
5396 } else {
5397 _g1h->verify_not_dirty_region(r);
5398 }
5399 return false;
5400 }
5401 };
5402
5403 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5404 // All of the region should be clean.
5405 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5406 MemRegion mr(hr->bottom(), hr->end());
5407 ct_bs->verify_not_dirty_region(mr);
5408 }
5409
5410 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5411 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5412 // dirty allocated blocks as they allocate them. The thread that
5413 // retires each region and replaces it with a new one will do a
5414 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5415 // not dirty that area (one less thing to have to do while holding
5416 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5417 // is dirty.
5418 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5419 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5420 if (hr->is_young()) {
5421 ct_bs->verify_g1_young_region(mr);
5422 } else {
5423 ct_bs->verify_dirty_region(mr);
5424 }
5425 }
5426
5427 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5428 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5429 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5430 verify_dirty_region(hr);
5431 }
5432 }
5433
5434 void G1CollectedHeap::verify_dirty_young_regions() {
5435 verify_dirty_young_list(_young_list->first_region());
5436 }
5437
5438 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5439 HeapWord* tams, HeapWord* end) {
5440 guarantee(tams <= end,
5441 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5442 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5443 if (result < end) {
5444 gclog_or_tty->cr();
5445 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5446 bitmap_name, p2i(result));
5447 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5448 bitmap_name, p2i(tams), p2i(end));
5449 return false;
5450 }
5451 return true;
5452 }
5453
5454 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5455 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5456 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5457
5458 HeapWord* bottom = hr->bottom();
5459 HeapWord* ptams = hr->prev_top_at_mark_start();
5460 HeapWord* ntams = hr->next_top_at_mark_start();
5461 HeapWord* end = hr->end();
5462
5463 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5464
5465 bool res_n = true;
5466 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5467 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5468 // if we happen to be in that state.
5469 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5470 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5471 }
5472 if (!res_p || !res_n) {
5473 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5474 HR_FORMAT_PARAMS(hr));
5475 gclog_or_tty->print_cr("#### Caller: %s", caller);
5476 return false;
5477 }
5478 return true;
5479 }
5480
5481 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5482 if (!G1VerifyBitmaps) return;
5483
5484 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5485 }
5486
5487 class G1VerifyBitmapClosure : public HeapRegionClosure {
5488 private:
5489 const char* _caller;
5490 G1CollectedHeap* _g1h;
5491 bool _failures;
5492
5493 public:
5494 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5495 _caller(caller), _g1h(g1h), _failures(false) { }
5496
5497 bool failures() { return _failures; }
5498
5499 virtual bool doHeapRegion(HeapRegion* hr) {
5500 if (hr->is_continues_humongous()) return false;
5501
5502 bool result = _g1h->verify_bitmaps(_caller, hr);
5503 if (!result) {
5504 _failures = true;
5505 }
5506 return false;
5507 }
5508 };
5509
5510 void G1CollectedHeap::check_bitmaps(const char* caller) {
5511 if (!G1VerifyBitmaps) return;
5512
5513 G1VerifyBitmapClosure cl(caller, this);
5514 heap_region_iterate(&cl);
5515 guarantee(!cl.failures(), "bitmap verification");
5516 }
5517
5518 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5519 private:
5520 bool _failures;
5521 public:
5522 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5523
5524 virtual bool doHeapRegion(HeapRegion* hr) {
5525 uint i = hr->hrm_index();
5526 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5527 if (hr->is_humongous()) {
5528 if (hr->in_collection_set()) {
5529 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5530 _failures = true;
5531 return true;
5532 }
5533 if (cset_state.is_in_cset()) {
5534 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5535 _failures = true;
5536 return true;
5537 }
5538 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5539 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5540 _failures = true;
5541 return true;
5542 }
5543 } else {
5544 if (cset_state.is_humongous()) {
5545 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5546 _failures = true;
5547 return true;
5548 }
5549 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5550 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5551 hr->in_collection_set(), cset_state.value(), i);
5552 _failures = true;
5553 return true;
5554 }
5555 if (cset_state.is_in_cset()) {
5556 if (hr->is_young() != (cset_state.is_young())) {
5557 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5558 hr->is_young(), cset_state.value(), i);
5559 _failures = true;
5560 return true;
5561 }
5562 if (hr->is_old() != (cset_state.is_old())) {
5563 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5564 hr->is_old(), cset_state.value(), i);
5565 _failures = true;
5566 return true;
5567 }
5568 }
5569 }
5570 return false;
5571 }
5572
5573 bool failures() const { return _failures; }
5574 };
5575
5576 bool G1CollectedHeap::check_cset_fast_test() {
5577 G1CheckCSetFastTableClosure cl;
5578 _hrm.iterate(&cl);
5579 return !cl.failures();
5580 }
5581 #endif // PRODUCT
5582
5583 void G1CollectedHeap::cleanUpCardTable() {
5584 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5585 double start = os::elapsedTime();
5586
5587 {
5588 // Iterate over the dirty cards region list.
5589 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5590
5591 workers()->run_task(&cleanup_task);
5592 #ifndef PRODUCT
5593 if (G1VerifyCTCleanup || VerifyAfterGC) {
5594 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5595 heap_region_iterate(&cleanup_verifier);
5596 }
5597 #endif
5598 }
5599
5600 double elapsed = os::elapsedTime() - start;
5601 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5602 }
5603
5604 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5605 size_t pre_used = 0;
5606 FreeRegionList local_free_list("Local List for CSet Freeing");
5607
5608 double young_time_ms = 0.0;
5609 double non_young_time_ms = 0.0;
5610
5611 // Since the collection set is a superset of the the young list,
5612 // all we need to do to clear the young list is clear its
5613 // head and length, and unlink any young regions in the code below
5614 _young_list->clear();
5615
5616 G1CollectorPolicy* policy = g1_policy();
5617
5618 double start_sec = os::elapsedTime();
5619 bool non_young = true;
5620
5621 HeapRegion* cur = cs_head;
5622 int age_bound = -1;
5623 size_t rs_lengths = 0;
5624
5625 while (cur != NULL) {
5626 assert(!is_on_master_free_list(cur), "sanity");
5627 if (non_young) {
5628 if (cur->is_young()) {
5629 double end_sec = os::elapsedTime();
5630 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5631 non_young_time_ms += elapsed_ms;
5632
5633 start_sec = os::elapsedTime();
5634 non_young = false;
5635 }
5636 } else {
5637 if (!cur->is_young()) {
5638 double end_sec = os::elapsedTime();
5639 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5640 young_time_ms += elapsed_ms;
5641
5642 start_sec = os::elapsedTime();
5643 non_young = true;
5644 }
5645 }
5646
5647 rs_lengths += cur->rem_set()->occupied_locked();
5648
5649 HeapRegion* next = cur->next_in_collection_set();
5650 assert(cur->in_collection_set(), "bad CS");
5651 cur->set_next_in_collection_set(NULL);
5652 clear_in_cset(cur);
5653
5654 if (cur->is_young()) {
5655 int index = cur->young_index_in_cset();
5656 assert(index != -1, "invariant");
5657 assert((uint) index < policy->young_cset_region_length(), "invariant");
5658 size_t words_survived = surviving_young_words[index];
5659 cur->record_surv_words_in_group(words_survived);
5660
5661 // At this point the we have 'popped' cur from the collection set
5662 // (linked via next_in_collection_set()) but it is still in the
5663 // young list (linked via next_young_region()). Clear the
5664 // _next_young_region field.
5665 cur->set_next_young_region(NULL);
5666 } else {
5667 int index = cur->young_index_in_cset();
5668 assert(index == -1, "invariant");
5669 }
5670
5671 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5672 (!cur->is_young() && cur->young_index_in_cset() == -1),
5673 "invariant" );
5674
5675 if (!cur->evacuation_failed()) {
5676 MemRegion used_mr = cur->used_region();
5677
5678 // And the region is empty.
5679 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5680 pre_used += cur->used();
5681 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5682 } else {
5683 cur->uninstall_surv_rate_group();
5684 if (cur->is_young()) {
5685 cur->set_young_index_in_cset(-1);
5686 }
5687 cur->set_evacuation_failed(false);
5688 // The region is now considered to be old.
5689 cur->set_old();
5690 // Do some allocation statistics accounting. Regions that failed evacuation
5691 // are always made old, so there is no need to update anything in the young
5692 // gen statistics, but we need to update old gen statistics.
5693 size_t used_words = cur->marked_bytes() / HeapWordSize;
5694 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5695 _old_set.add(cur);
5696 evacuation_info.increment_collectionset_used_after(cur->used());
5697 }
5698 cur = next;
5699 }
5700
5701 evacuation_info.set_regions_freed(local_free_list.length());
5702 policy->record_max_rs_lengths(rs_lengths);
5703 policy->cset_regions_freed();
5704
5705 double end_sec = os::elapsedTime();
5706 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5707
5708 if (non_young) {
5709 non_young_time_ms += elapsed_ms;
5710 } else {
5711 young_time_ms += elapsed_ms;
5712 }
5713
5714 prepend_to_freelist(&local_free_list);
5715 decrement_summary_bytes(pre_used);
5716 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5717 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5718 }
5719
5720 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5721 private:
5722 FreeRegionList* _free_region_list;
5723 HeapRegionSet* _proxy_set;
5724 HeapRegionSetCount _humongous_regions_removed;
5725 size_t _freed_bytes;
5726 public:
5727
5728 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5729 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5730 }
5731
5732 virtual bool doHeapRegion(HeapRegion* r) {
5733 if (!r->is_starts_humongous()) {
5734 return false;
5735 }
5736
5737 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5738
5739 oop obj = (oop)r->bottom();
5740 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5741
5742 // The following checks whether the humongous object is live are sufficient.
5743 // The main additional check (in addition to having a reference from the roots
5744 // or the young gen) is whether the humongous object has a remembered set entry.
5745 //
5746 // A humongous object cannot be live if there is no remembered set for it
5747 // because:
5748 // - there can be no references from within humongous starts regions referencing
5749 // the object because we never allocate other objects into them.
5750 // (I.e. there are no intra-region references that may be missed by the
5751 // remembered set)
5752 // - as soon there is a remembered set entry to the humongous starts region
5753 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5754 // until the end of a concurrent mark.
5755 //
5756 // It is not required to check whether the object has been found dead by marking
5757 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5758 // all objects allocated during that time are considered live.
5759 // SATB marking is even more conservative than the remembered set.
5760 // So if at this point in the collection there is no remembered set entry,
5761 // nobody has a reference to it.
5762 // At the start of collection we flush all refinement logs, and remembered sets
5763 // are completely up-to-date wrt to references to the humongous object.
5764 //
5765 // Other implementation considerations:
5766 // - never consider object arrays at this time because they would pose
5767 // considerable effort for cleaning up the the remembered sets. This is
5768 // required because stale remembered sets might reference locations that
5769 // are currently allocated into.
5770 uint region_idx = r->hrm_index();
5771 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5772 !r->rem_set()->is_empty()) {
5773
5774 if (G1TraceEagerReclaimHumongousObjects) {
5775 gclog_or_tty->print_cr("Live humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5776 region_idx,
5777 (size_t)obj->size() * HeapWordSize,
5778 p2i(r->bottom()),
5779 r->region_num(),
5780 r->rem_set()->occupied(),
5781 r->rem_set()->strong_code_roots_list_length(),
5782 next_bitmap->isMarked(r->bottom()),
5783 g1h->is_humongous_reclaim_candidate(region_idx),
5784 obj->is_typeArray()
5785 );
5786 }
5787
5788 return false;
5789 }
5790
5791 guarantee(obj->is_typeArray(),
5792 "Only eagerly reclaiming type arrays is supported, but the object "
5793 PTR_FORMAT " is not.", p2i(r->bottom()));
5794
5795 if (G1TraceEagerReclaimHumongousObjects) {
5796 gclog_or_tty->print_cr("Dead humongous region %u size " SIZE_FORMAT " start " PTR_FORMAT " length %u with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5797 region_idx,
5798 (size_t)obj->size() * HeapWordSize,
5799 p2i(r->bottom()),
5800 r->region_num(),
5801 r->rem_set()->occupied(),
5802 r->rem_set()->strong_code_roots_list_length(),
5803 next_bitmap->isMarked(r->bottom()),
5804 g1h->is_humongous_reclaim_candidate(region_idx),
5805 obj->is_typeArray()
5806 );
5807 }
5808 // Need to clear mark bit of the humongous object if already set.
5809 if (next_bitmap->isMarked(r->bottom())) {
5810 next_bitmap->clear(r->bottom());
5811 }
5812 _freed_bytes += r->used();
5813 r->set_containing_set(NULL);
5814 _humongous_regions_removed.increment(1u, r->capacity());
5815 g1h->free_humongous_region(r, _free_region_list, false);
5816
5817 return false;
5818 }
5819
5820 HeapRegionSetCount& humongous_free_count() {
5821 return _humongous_regions_removed;
5822 }
5823
5824 size_t bytes_freed() const {
5825 return _freed_bytes;
5826 }
5827
5828 size_t humongous_reclaimed() const {
5829 return _humongous_regions_removed.length();
5830 }
5831 };
5832
5833 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5834 assert_at_safepoint(true);
5835
5836 if (!G1EagerReclaimHumongousObjects ||
5837 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5838 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5839 return;
5840 }
5841
5842 double start_time = os::elapsedTime();
5843
5844 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5845
5846 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5847 heap_region_iterate(&cl);
5848
5849 HeapRegionSetCount empty_set;
5850 remove_from_old_sets(empty_set, cl.humongous_free_count());
5851
5852 G1HRPrinter* hrp = hr_printer();
5853 if (hrp->is_active()) {
5854 FreeRegionListIterator iter(&local_cleanup_list);
5855 while (iter.more_available()) {
5856 HeapRegion* hr = iter.get_next();
5857 hrp->cleanup(hr);
5858 }
5859 }
5860
5861 prepend_to_freelist(&local_cleanup_list);
5862 decrement_summary_bytes(cl.bytes_freed());
5863
5864 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5865 cl.humongous_reclaimed());
5866 }
5867
5868 // This routine is similar to the above but does not record
5869 // any policy statistics or update free lists; we are abandoning
5870 // the current incremental collection set in preparation of a
5871 // full collection. After the full GC we will start to build up
5872 // the incremental collection set again.
5873 // This is only called when we're doing a full collection
5874 // and is immediately followed by the tearing down of the young list.
5875
5876 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5877 HeapRegion* cur = cs_head;
5878
5879 while (cur != NULL) {
5880 HeapRegion* next = cur->next_in_collection_set();
5881 assert(cur->in_collection_set(), "bad CS");
5882 cur->set_next_in_collection_set(NULL);
5883 clear_in_cset(cur);
5884 cur->set_young_index_in_cset(-1);
5885 cur = next;
5886 }
5887 }
5888
5889 void G1CollectedHeap::set_free_regions_coming() {
5890 if (G1ConcRegionFreeingVerbose) {
5891 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5892 "setting free regions coming");
5893 }
5894
5895 assert(!free_regions_coming(), "pre-condition");
5896 _free_regions_coming = true;
5897 }
5898
5899 void G1CollectedHeap::reset_free_regions_coming() {
5900 assert(free_regions_coming(), "pre-condition");
5901
5902 {
5903 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5904 _free_regions_coming = false;
5905 SecondaryFreeList_lock->notify_all();
5906 }
5907
5908 if (G1ConcRegionFreeingVerbose) {
5909 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5910 "reset free regions coming");
5911 }
5912 }
5913
5914 void G1CollectedHeap::wait_while_free_regions_coming() {
5915 // Most of the time we won't have to wait, so let's do a quick test
5916 // first before we take the lock.
5917 if (!free_regions_coming()) {
5918 return;
5919 }
5920
5921 if (G1ConcRegionFreeingVerbose) {
5922 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5923 "waiting for free regions");
5924 }
5925
5926 {
5927 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5928 while (free_regions_coming()) {
5929 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5930 }
5931 }
5932
5933 if (G1ConcRegionFreeingVerbose) {
5934 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5935 "done waiting for free regions");
5936 }
5937 }
5938
5939 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5940 return _allocator->is_retained_old_region(hr);
5941 }
5942
5943 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5944 _young_list->push_region(hr);
5945 }
5946
5947 class NoYoungRegionsClosure: public HeapRegionClosure {
5948 private:
5949 bool _success;
5950 public:
5951 NoYoungRegionsClosure() : _success(true) { }
5952 bool doHeapRegion(HeapRegion* r) {
5953 if (r->is_young()) {
5954 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5955 p2i(r->bottom()), p2i(r->end()));
5956 _success = false;
5957 }
5958 return false;
5959 }
5960 bool success() { return _success; }
5961 };
5962
5963 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5964 bool ret = _young_list->check_list_empty(check_sample);
5965
5966 if (check_heap) {
5967 NoYoungRegionsClosure closure;
5968 heap_region_iterate(&closure);
5969 ret = ret && closure.success();
5970 }
5971
5972 return ret;
5973 }
5974
5975 class TearDownRegionSetsClosure : public HeapRegionClosure {
5976 private:
5977 HeapRegionSet *_old_set;
5978
5979 public:
5980 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5981
5982 bool doHeapRegion(HeapRegion* r) {
5983 if (r->is_old()) {
5984 _old_set->remove(r);
5985 } else {
5986 // We ignore free regions, we'll empty the free list afterwards.
5987 // We ignore young regions, we'll empty the young list afterwards.
5988 // We ignore humongous regions, we're not tearing down the
5989 // humongous regions set.
5990 assert(r->is_free() || r->is_young() || r->is_humongous(),
5991 "it cannot be another type");
5992 }
5993 return false;
5994 }
5995
5996 ~TearDownRegionSetsClosure() {
5997 assert(_old_set->is_empty(), "post-condition");
5998 }
5999 };
6000
6001 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6002 assert_at_safepoint(true /* should_be_vm_thread */);
6003
6004 if (!free_list_only) {
6005 TearDownRegionSetsClosure cl(&_old_set);
6006 heap_region_iterate(&cl);
6007
6008 // Note that emptying the _young_list is postponed and instead done as
6009 // the first step when rebuilding the regions sets again. The reason for
6010 // this is that during a full GC string deduplication needs to know if
6011 // a collected region was young or old when the full GC was initiated.
6012 }
6013 _hrm.remove_all_free_regions();
6014 }
6015
6016 void G1CollectedHeap::increase_used(size_t bytes) {
6017 _summary_bytes_used += bytes;
6018 }
6019
6020 void G1CollectedHeap::decrease_used(size_t bytes) {
6021 assert(_summary_bytes_used >= bytes,
6022 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6023 _summary_bytes_used, bytes);
6024 _summary_bytes_used -= bytes;
6025 }
6026
6027 void G1CollectedHeap::set_used(size_t bytes) {
6028 _summary_bytes_used = bytes;
6029 }
6030
6031 class RebuildRegionSetsClosure : public HeapRegionClosure {
6032 private:
6033 bool _free_list_only;
6034 HeapRegionSet* _old_set;
6035 HeapRegionManager* _hrm;
6036 size_t _total_used;
6037
6038 public:
6039 RebuildRegionSetsClosure(bool free_list_only,
6040 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6041 _free_list_only(free_list_only),
6042 _old_set(old_set), _hrm(hrm), _total_used(0) {
6043 assert(_hrm->num_free_regions() == 0, "pre-condition");
6044 if (!free_list_only) {
6045 assert(_old_set->is_empty(), "pre-condition");
6046 }
6047 }
6048
6049 bool doHeapRegion(HeapRegion* r) {
6050 if (r->is_continues_humongous()) {
6051 return false;
6052 }
6053
6054 if (r->is_empty()) {
6055 // Add free regions to the free list
6056 r->set_free();
6057 r->set_allocation_context(AllocationContext::system());
6058 _hrm->insert_into_free_list(r);
6059 } else if (!_free_list_only) {
6060 assert(!r->is_young(), "we should not come across young regions");
6061
6062 if (r->is_humongous()) {
6063 // We ignore humongous regions. We left the humongous set unchanged.
6064 } else {
6065 // Objects that were compacted would have ended up on regions
6066 // that were previously old or free. Archive regions (which are
6067 // old) will not have been touched.
6068 assert(r->is_free() || r->is_old(), "invariant");
6069 // We now consider them old, so register as such. Leave
6070 // archive regions set that way, however, while still adding
6071 // them to the old set.
6072 if (!r->is_archive()) {
6073 r->set_old();
6074 }
6075 _old_set->add(r);
6076 }
6077 _total_used += r->used();
6078 }
6079
6080 return false;
6081 }
6082
6083 size_t total_used() {
6084 return _total_used;
6085 }
6086 };
6087
6088 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6089 assert_at_safepoint(true /* should_be_vm_thread */);
6090
6091 if (!free_list_only) {
6092 _young_list->empty_list();
6093 }
6094
6095 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6096 heap_region_iterate(&cl);
6097
6098 if (!free_list_only) {
6099 set_used(cl.total_used());
6100 if (_archive_allocator != NULL) {
6101 _archive_allocator->clear_used();
6102 }
6103 }
6104 assert(used_unlocked() == recalculate_used(),
6105 "inconsistent used_unlocked(), "
6106 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6107 used_unlocked(), recalculate_used());
6108 }
6109
6110 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6111 _refine_cte_cl->set_concurrent(concurrent);
6112 }
6113
6114 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6115 HeapRegion* hr = heap_region_containing(p);
6116 return hr->is_in(p);
6117 }
6118
6119 // Methods for the mutator alloc region
6120
6121 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6122 bool force) {
6123 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6124 assert(!force || g1_policy()->can_expand_young_list(),
6125 "if force is true we should be able to expand the young list");
6126 bool young_list_full = g1_policy()->is_young_list_full();
6127 if (force || !young_list_full) {
6128 HeapRegion* new_alloc_region = new_region(word_size,
6129 false /* is_old */,
6130 false /* do_expand */);
6131 if (new_alloc_region != NULL) {
6132 set_region_short_lived_locked(new_alloc_region);
6133 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6134 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6135 return new_alloc_region;
6136 }
6137 }
6138 return NULL;
6139 }
6140
6141 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6142 size_t allocated_bytes) {
6143 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6144 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6145
6146 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6147 increase_used(allocated_bytes);
6148 _hr_printer.retire(alloc_region);
6149 // We update the eden sizes here, when the region is retired,
6150 // instead of when it's allocated, since this is the point that its
6151 // used space has been recored in _summary_bytes_used.
6152 g1mm()->update_eden_size();
6153 }
6154
6155 // Methods for the GC alloc regions
6156
6157 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6158 uint count,
6159 InCSetState dest) {
6160 assert(FreeList_lock->owned_by_self(), "pre-condition");
6161
6162 if (count < g1_policy()->max_regions(dest)) {
6163 const bool is_survivor = (dest.is_young());
6164 HeapRegion* new_alloc_region = new_region(word_size,
6165 !is_survivor,
6166 true /* do_expand */);
6167 if (new_alloc_region != NULL) {
6168 // We really only need to do this for old regions given that we
6169 // should never scan survivors. But it doesn't hurt to do it
6170 // for survivors too.
6171 new_alloc_region->record_timestamp();
6172 if (is_survivor) {
6173 new_alloc_region->set_survivor();
6174 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6175 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6176 } else {
6177 new_alloc_region->set_old();
6178 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6179 check_bitmaps("Old Region Allocation", new_alloc_region);
6180 }
6181 bool during_im = collector_state()->during_initial_mark_pause();
6182 new_alloc_region->note_start_of_copying(during_im);
6183 return new_alloc_region;
6184 }
6185 }
6186 return NULL;
6187 }
6188
6189 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6190 size_t allocated_bytes,
6191 InCSetState dest) {
6192 bool during_im = collector_state()->during_initial_mark_pause();
6193 alloc_region->note_end_of_copying(during_im);
6194 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6195 if (dest.is_young()) {
6196 young_list()->add_survivor_region(alloc_region);
6197 } else {
6198 _old_set.add(alloc_region);
6199 }
6200 _hr_printer.retire(alloc_region);
6201 }
6202
6203 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6204 bool expanded = false;
6205 uint index = _hrm.find_highest_free(&expanded);
6206
6207 if (index != G1_NO_HRM_INDEX) {
6208 if (expanded) {
6209 ergo_verbose1(ErgoHeapSizing,
6210 "attempt heap expansion",
6211 ergo_format_reason("requested address range outside heap bounds")
6212 ergo_format_byte("region size"),
6213 HeapRegion::GrainWords * HeapWordSize);
6214 }
6215 _hrm.allocate_free_regions_starting_at(index, 1);
6216 return region_at(index);
6217 }
6218 return NULL;
6219 }
6220
6221 // Heap region set verification
6222
6223 class VerifyRegionListsClosure : public HeapRegionClosure {
6224 private:
6225 HeapRegionSet* _old_set;
6226 HeapRegionSet* _humongous_set;
6227 HeapRegionManager* _hrm;
6228
6229 public:
6230 HeapRegionSetCount _old_count;
6231 HeapRegionSetCount _humongous_count;
6232 HeapRegionSetCount _free_count;
6233
6234 VerifyRegionListsClosure(HeapRegionSet* old_set,
6235 HeapRegionSet* humongous_set,
6236 HeapRegionManager* hrm) :
6237 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6238 _old_count(), _humongous_count(), _free_count(){ }
6239
6240 bool doHeapRegion(HeapRegion* hr) {
6241 if (hr->is_continues_humongous()) {
6242 return false;
6243 }
6244
6245 if (hr->is_young()) {
6246 // TODO
6247 } else if (hr->is_starts_humongous()) {
6248 assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index());
6249 _humongous_count.increment(1u, hr->capacity());
6250 } else if (hr->is_empty()) {
6251 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6252 _free_count.increment(1u, hr->capacity());
6253 } else if (hr->is_old()) {
6254 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6255 _old_count.increment(1u, hr->capacity());
6256 } else {
6257 // There are no other valid region types. Check for one invalid
6258 // one we can identify: pinned without old or humongous set.
6259 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6260 ShouldNotReachHere();
6261 }
6262 return false;
6263 }
6264
6265 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6266 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6267 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6268 old_set->total_capacity_bytes(), _old_count.capacity());
6269
6270 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6271 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6272 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6273
6274 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());
6275 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6276 free_list->total_capacity_bytes(), _free_count.capacity());
6277 }
6278 };
6279
6280 void G1CollectedHeap::verify_region_sets() {
6281 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6282
6283 // First, check the explicit lists.
6284 _hrm.verify();
6285 {
6286 // Given that a concurrent operation might be adding regions to
6287 // the secondary free list we have to take the lock before
6288 // verifying it.
6289 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6290 _secondary_free_list.verify_list();
6291 }
6292
6293 // If a concurrent region freeing operation is in progress it will
6294 // be difficult to correctly attributed any free regions we come
6295 // across to the correct free list given that they might belong to
6296 // one of several (free_list, secondary_free_list, any local lists,
6297 // etc.). So, if that's the case we will skip the rest of the
6298 // verification operation. Alternatively, waiting for the concurrent
6299 // operation to complete will have a non-trivial effect on the GC's
6300 // operation (no concurrent operation will last longer than the
6301 // interval between two calls to verification) and it might hide
6302 // any issues that we would like to catch during testing.
6303 if (free_regions_coming()) {
6304 return;
6305 }
6306
6307 // Make sure we append the secondary_free_list on the free_list so
6308 // that all free regions we will come across can be safely
6309 // attributed to the free_list.
6310 append_secondary_free_list_if_not_empty_with_lock();
6311
6312 // Finally, make sure that the region accounting in the lists is
6313 // consistent with what we see in the heap.
6314
6315 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6316 heap_region_iterate(&cl);
6317 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6318 }
6319
6320 // Optimized nmethod scanning
6321
6322 class RegisterNMethodOopClosure: public OopClosure {
6323 G1CollectedHeap* _g1h;
6324 nmethod* _nm;
6325
6326 template <class T> void do_oop_work(T* p) {
6327 T heap_oop = oopDesc::load_heap_oop(p);
6328 if (!oopDesc::is_null(heap_oop)) {
6329 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6330 HeapRegion* hr = _g1h->heap_region_containing(obj);
6331 assert(!hr->is_continues_humongous(),
6332 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6333 " starting at " HR_FORMAT,
6334 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6335
6336 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6337 hr->add_strong_code_root_locked(_nm);
6338 }
6339 }
6340
6341 public:
6342 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6343 _g1h(g1h), _nm(nm) {}
6344
6345 void do_oop(oop* p) { do_oop_work(p); }
6346 void do_oop(narrowOop* p) { do_oop_work(p); }
6347 };
6348
6349 class UnregisterNMethodOopClosure: public OopClosure {
6350 G1CollectedHeap* _g1h;
6351 nmethod* _nm;
6352
6353 template <class T> void do_oop_work(T* p) {
6354 T heap_oop = oopDesc::load_heap_oop(p);
6355 if (!oopDesc::is_null(heap_oop)) {
6356 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6357 HeapRegion* hr = _g1h->heap_region_containing(obj);
6358 assert(!hr->is_continues_humongous(),
6359 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6360 " starting at " HR_FORMAT,
6361 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6362
6363 hr->remove_strong_code_root(_nm);
6364 }
6365 }
6366
6367 public:
6368 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6369 _g1h(g1h), _nm(nm) {}
6370
6371 void do_oop(oop* p) { do_oop_work(p); }
6372 void do_oop(narrowOop* p) { do_oop_work(p); }
6373 };
6374
6375 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6376 CollectedHeap::register_nmethod(nm);
6377
6378 guarantee(nm != NULL, "sanity");
6379 RegisterNMethodOopClosure reg_cl(this, nm);
6380 nm->oops_do(®_cl);
6381 }
6382
6383 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6384 CollectedHeap::unregister_nmethod(nm);
6385
6386 guarantee(nm != NULL, "sanity");
6387 UnregisterNMethodOopClosure reg_cl(this, nm);
6388 nm->oops_do(®_cl, true);
6389 }
6390
6391 void G1CollectedHeap::purge_code_root_memory() {
6392 double purge_start = os::elapsedTime();
6393 G1CodeRootSet::purge();
6394 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6395 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6396 }
6397
6398 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6399 G1CollectedHeap* _g1h;
6400
6401 public:
6402 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6403 _g1h(g1h) {}
6404
6405 void do_code_blob(CodeBlob* cb) {
6406 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6407 if (nm == NULL) {
6408 return;
6409 }
6410
6411 if (ScavengeRootsInCode) {
6412 _g1h->register_nmethod(nm);
6413 }
6414 }
6415 };
6416
6417 void G1CollectedHeap::rebuild_strong_code_roots() {
6418 RebuildStrongCodeRootClosure blob_cl(this);
6419 CodeCache::blobs_do(&blob_cl);
6420 }