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 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1811 CollectedHeap(),
1812 _g1_policy(policy_),
1813 _dirty_card_queue_set(false),
1814 _into_cset_dirty_card_queue_set(false),
1815 _is_alive_closure_cm(this),
1816 _is_alive_closure_stw(this),
1817 _ref_processor_cm(NULL),
1818 _ref_processor_stw(NULL),
1819 _bot_shared(NULL),
1820 _cg1r(NULL),
1821 _g1mm(NULL),
1822 _refine_cte_cl(NULL),
1823 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1824 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1825 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1826 _humongous_reclaim_candidates(),
1827 _has_humongous_reclaim_candidates(false),
1828 _archive_allocator(NULL),
1829 _free_regions_coming(false),
1830 _young_list(new YoungList(this)),
1831 _gc_time_stamp(0),
1832 _summary_bytes_used(0),
1833 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1834 _old_evac_stats(OldPLABSize, PLABWeight),
1835 _expand_heap_after_alloc_failure(true),
1836 _old_marking_cycles_started(0),
1837 _old_marking_cycles_completed(0),
1838 _heap_summary_sent(false),
1839 _in_cset_fast_test(),
1840 _dirty_cards_region_list(NULL),
1841 _worker_cset_start_region(NULL),
1842 _worker_cset_start_region_time_stamp(NULL),
1843 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1844 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1845 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1846 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1847
1848 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1849 /* are_GC_task_threads */true,
1850 /* are_ConcurrentGC_threads */false);
1851 _workers->initialize_workers();
1852
1853 _allocator = G1Allocator::create_allocator(this);
1854 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1855
1856 // Override the default _filler_array_max_size so that no humongous filler
1857 // objects are created.
1858 _filler_array_max_size = _humongous_object_threshold_in_words;
1859
1860 uint n_queues = ParallelGCThreads;
1861 _task_queues = new RefToScanQueueSet(n_queues);
1862
1863 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1864 assert(n_rem_sets > 0, "Invariant.");
1865
1866 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1867 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1868 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1869
1870 for (uint i = 0; i < n_queues; i++) {
1871 RefToScanQueue* q = new RefToScanQueue();
1872 q->initialize();
1873 _task_queues->register_queue(i, q);
1874 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1875 }
1876 clear_cset_start_regions();
1877
1878 // Initialize the G1EvacuationFailureALot counters and flags.
1879 NOT_PRODUCT(reset_evacuation_should_fail();)
1880
1881 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1882 }
1883
1884 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1885 size_t size,
1886 size_t translation_factor) {
1887 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1888 // Allocate a new reserved space, preferring to use large pages.
1889 ReservedSpace rs(size, preferred_page_size);
1890 G1RegionToSpaceMapper* result =
1891 G1RegionToSpaceMapper::create_mapper(rs,
1892 size,
1893 rs.alignment(),
1894 HeapRegion::GrainBytes,
1895 translation_factor,
1896 mtGC);
1897 if (TracePageSizes) {
1898 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1899 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1900 }
1901 return result;
1902 }
1903
1904 jint G1CollectedHeap::initialize() {
1905 CollectedHeap::pre_initialize();
1906 os::enable_vtime();
1907
1908 G1Log::init();
1909
1910 // Necessary to satisfy locking discipline assertions.
1911
1912 MutexLocker x(Heap_lock);
1913
1914 // We have to initialize the printer before committing the heap, as
1915 // it will be used then.
1916 _hr_printer.set_active(G1PrintHeapRegions);
1917
1918 // While there are no constraints in the GC code that HeapWordSize
1919 // be any particular value, there are multiple other areas in the
1920 // system which believe this to be true (e.g. oop->object_size in some
1921 // cases incorrectly returns the size in wordSize units rather than
1922 // HeapWordSize).
1923 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1924
1925 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1926 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1927 size_t heap_alignment = collector_policy()->heap_alignment();
1928
1929 // Ensure that the sizes are properly aligned.
1930 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1931 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1932 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1933
1934 _refine_cte_cl = new RefineCardTableEntryClosure();
1935
1936 jint ecode = JNI_OK;
1937 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1938 if (_cg1r == NULL) {
1939 return ecode;
1940 }
1941
1942 // Reserve the maximum.
1943
1944 // When compressed oops are enabled, the preferred heap base
1945 // is calculated by subtracting the requested size from the
1946 // 32Gb boundary and using the result as the base address for
1947 // heap reservation. If the requested size is not aligned to
1948 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1949 // into the ReservedHeapSpace constructor) then the actual
1950 // base of the reserved heap may end up differing from the
1951 // address that was requested (i.e. the preferred heap base).
1952 // If this happens then we could end up using a non-optimal
1953 // compressed oops mode.
1954
1955 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1956 heap_alignment);
1957
1958 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1959
1960 // Create the barrier set for the entire reserved region.
1961 G1SATBCardTableLoggingModRefBS* bs
1962 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1963 bs->initialize();
1964 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1965 set_barrier_set(bs);
1966
1967 // Also create a G1 rem set.
1968 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1969
1970 // Carve out the G1 part of the heap.
1971
1972 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1973 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1974 G1RegionToSpaceMapper* heap_storage =
1975 G1RegionToSpaceMapper::create_mapper(g1_rs,
1976 g1_rs.size(),
1977 page_size,
1978 HeapRegion::GrainBytes,
1979 1,
1980 mtJavaHeap);
1981 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1982 max_byte_size, page_size,
1983 heap_rs.base(),
1984 heap_rs.size());
1985 heap_storage->set_mapping_changed_listener(&_listener);
1986
1987 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1988 G1RegionToSpaceMapper* bot_storage =
1989 create_aux_memory_mapper("Block offset table",
1990 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1991 G1BlockOffsetSharedArray::heap_map_factor());
1992
1993 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1994 G1RegionToSpaceMapper* cardtable_storage =
1995 create_aux_memory_mapper("Card table",
1996 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1997 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1998
1999 G1RegionToSpaceMapper* card_counts_storage =
2000 create_aux_memory_mapper("Card counts table",
2001 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2002 G1CardCounts::heap_map_factor());
2003
2004 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2005 G1RegionToSpaceMapper* prev_bitmap_storage =
2006 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2007 G1RegionToSpaceMapper* next_bitmap_storage =
2008 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2009
2010 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2011 g1_barrier_set()->initialize(cardtable_storage);
2012 // Do later initialization work for concurrent refinement.
2013 _cg1r->init(card_counts_storage);
2014
2015 // 6843694 - ensure that the maximum region index can fit
2016 // in the remembered set structures.
2017 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2018 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2019
2020 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2021 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2022 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2023 "too many cards per region");
2024
2025 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2026
2027 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2028
2029 {
2030 HeapWord* start = _hrm.reserved().start();
2031 HeapWord* end = _hrm.reserved().end();
2032 size_t granularity = HeapRegion::GrainBytes;
2033
2034 _in_cset_fast_test.initialize(start, end, granularity);
2035 _humongous_reclaim_candidates.initialize(start, end, granularity);
2036 }
2037
2038 // Create the ConcurrentMark data structure and thread.
2039 // (Must do this late, so that "max_regions" is defined.)
2040 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2041 if (_cm == NULL || !_cm->completed_initialization()) {
2042 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2043 return JNI_ENOMEM;
2044 }
2045 _cmThread = _cm->cmThread();
2046
2047 // Initialize the from_card cache structure of HeapRegionRemSet.
2048 HeapRegionRemSet::init_heap(max_regions());
2049
2050 // Now expand into the initial heap size.
2051 if (!expand(init_byte_size)) {
2052 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2053 return JNI_ENOMEM;
2054 }
2055
2056 // Perform any initialization actions delegated to the policy.
2057 g1_policy()->init();
2058
2059 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2060 SATB_Q_FL_lock,
2061 G1SATBProcessCompletedThreshold,
2062 Shared_SATB_Q_lock);
2063
2064 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2065 DirtyCardQ_CBL_mon,
2066 DirtyCardQ_FL_lock,
2067 concurrent_g1_refine()->yellow_zone(),
2068 concurrent_g1_refine()->red_zone(),
2069 Shared_DirtyCardQ_lock);
2070
2071 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2072 DirtyCardQ_CBL_mon,
2073 DirtyCardQ_FL_lock,
2074 -1, // never trigger processing
2075 -1, // no limit on length
2076 Shared_DirtyCardQ_lock,
2077 &JavaThread::dirty_card_queue_set());
2078
2079 // Initialize the card queue set used to hold cards containing
2080 // references into the collection set.
2081 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2082 DirtyCardQ_CBL_mon,
2083 DirtyCardQ_FL_lock,
2084 -1, // never trigger processing
2085 -1, // no limit on length
2086 Shared_DirtyCardQ_lock,
2087 &JavaThread::dirty_card_queue_set());
2088
2089 // Here we allocate the dummy HeapRegion that is required by the
2090 // G1AllocRegion class.
2091 HeapRegion* dummy_region = _hrm.get_dummy_region();
2092
2093 // We'll re-use the same region whether the alloc region will
2094 // require BOT updates or not and, if it doesn't, then a non-young
2095 // region will complain that it cannot support allocations without
2096 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2097 dummy_region->set_eden();
2098 // Make sure it's full.
2099 dummy_region->set_top(dummy_region->end());
2100 G1AllocRegion::setup(this, dummy_region);
2101
2102 _allocator->init_mutator_alloc_region();
2103
2104 // Do create of the monitoring and management support so that
2105 // values in the heap have been properly initialized.
2106 _g1mm = new G1MonitoringSupport(this);
2107
2108 G1StringDedup::initialize();
2109
2110 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2111 for (uint i = 0; i < ParallelGCThreads; i++) {
2112 new (&_preserved_objs[i]) OopAndMarkOopStack();
2113 }
2114
2115 return JNI_OK;
2116 }
2117
2118 void G1CollectedHeap::stop() {
2119 // Stop all concurrent threads. We do this to make sure these threads
2120 // do not continue to execute and access resources (e.g. gclog_or_tty)
2121 // that are destroyed during shutdown.
2122 _cg1r->stop();
2123 _cmThread->stop();
2124 if (G1StringDedup::is_enabled()) {
2125 G1StringDedup::stop();
2126 }
2127 }
2128
2129 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2130 return HeapRegion::max_region_size();
2131 }
2132
2133 void G1CollectedHeap::post_initialize() {
2134 CollectedHeap::post_initialize();
2135 ref_processing_init();
2136 }
2137
2138 void G1CollectedHeap::ref_processing_init() {
2139 // Reference processing in G1 currently works as follows:
2140 //
2141 // * There are two reference processor instances. One is
2142 // used to record and process discovered references
2143 // during concurrent marking; the other is used to
2144 // record and process references during STW pauses
2145 // (both full and incremental).
2146 // * Both ref processors need to 'span' the entire heap as
2147 // the regions in the collection set may be dotted around.
2148 //
2149 // * For the concurrent marking ref processor:
2150 // * Reference discovery is enabled at initial marking.
2151 // * Reference discovery is disabled and the discovered
2152 // references processed etc during remarking.
2153 // * Reference discovery is MT (see below).
2154 // * Reference discovery requires a barrier (see below).
2155 // * Reference processing may or may not be MT
2156 // (depending on the value of ParallelRefProcEnabled
2157 // and ParallelGCThreads).
2158 // * A full GC disables reference discovery by the CM
2159 // ref processor and abandons any entries on it's
2160 // discovered lists.
2161 //
2162 // * For the STW processor:
2163 // * Non MT discovery is enabled at the start of a full GC.
2164 // * Processing and enqueueing during a full GC is non-MT.
2165 // * During a full GC, references are processed after marking.
2166 //
2167 // * Discovery (may or may not be MT) is enabled at the start
2168 // of an incremental evacuation pause.
2169 // * References are processed near the end of a STW evacuation pause.
2170 // * For both types of GC:
2171 // * Discovery is atomic - i.e. not concurrent.
2172 // * Reference discovery will not need a barrier.
2173
2174 MemRegion mr = reserved_region();
2175
2176 // Concurrent Mark ref processor
2177 _ref_processor_cm =
2178 new ReferenceProcessor(mr, // span
2179 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2180 // mt processing
2181 ParallelGCThreads,
2182 // degree of mt processing
2183 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2184 // mt discovery
2185 MAX2(ParallelGCThreads, ConcGCThreads),
2186 // degree of mt discovery
2187 false,
2188 // Reference discovery is not atomic
2189 &_is_alive_closure_cm);
2190 // is alive closure
2191 // (for efficiency/performance)
2192
2193 // STW ref processor
2194 _ref_processor_stw =
2195 new ReferenceProcessor(mr, // span
2196 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2197 // mt processing
2198 ParallelGCThreads,
2199 // degree of mt processing
2200 (ParallelGCThreads > 1),
2201 // mt discovery
2202 ParallelGCThreads,
2203 // degree of mt discovery
2204 true,
2205 // Reference discovery is atomic
2206 &_is_alive_closure_stw);
2207 // is alive closure
2208 // (for efficiency/performance)
2209 }
2210
2211 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2212 return g1_policy();
2213 }
2214
2215 size_t G1CollectedHeap::capacity() const {
2216 return _hrm.length() * HeapRegion::GrainBytes;
2217 }
2218
2219 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2220 assert(!hr->is_continues_humongous(), "pre-condition");
2221 hr->reset_gc_time_stamp();
2222 if (hr->is_starts_humongous()) {
2223 uint first_index = hr->hrm_index() + 1;
2224 uint last_index = hr->last_hc_index();
2225 for (uint i = first_index; i < last_index; i += 1) {
2226 HeapRegion* chr = region_at(i);
2227 assert(chr->is_continues_humongous(), "sanity");
2228 chr->reset_gc_time_stamp();
2229 }
2230 }
2231 }
2232
2233 #ifndef PRODUCT
2234
2235 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2236 private:
2237 unsigned _gc_time_stamp;
2238 bool _failures;
2239
2240 public:
2241 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2242 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2243
2244 virtual bool doHeapRegion(HeapRegion* hr) {
2245 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2246 if (_gc_time_stamp != region_gc_time_stamp) {
2247 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2248 "expected %d", HR_FORMAT_PARAMS(hr),
2249 region_gc_time_stamp, _gc_time_stamp);
2250 _failures = true;
2251 }
2252 return false;
2253 }
2254
2255 bool failures() { return _failures; }
2256 };
2257
2258 void G1CollectedHeap::check_gc_time_stamps() {
2259 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2260 heap_region_iterate(&cl);
2261 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2262 }
2263 #endif // PRODUCT
2264
2265 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2266 _cg1r->hot_card_cache()->drain(cl, worker_i);
2267 }
2268
2269 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2270 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2271 size_t n_completed_buffers = 0;
2272 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2273 n_completed_buffers++;
2274 }
2275 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2276 dcqs.clear_n_completed_buffers();
2277 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2278 }
2279
2280 // Computes the sum of the storage used by the various regions.
2281 size_t G1CollectedHeap::used() const {
2282 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2283 if (_archive_allocator != NULL) {
2284 result += _archive_allocator->used();
2285 }
2286 return result;
2287 }
2288
2289 size_t G1CollectedHeap::used_unlocked() const {
2290 return _summary_bytes_used;
2291 }
2292
2293 class SumUsedClosure: public HeapRegionClosure {
2294 size_t _used;
2295 public:
2296 SumUsedClosure() : _used(0) {}
2297 bool doHeapRegion(HeapRegion* r) {
2298 if (!r->is_continues_humongous()) {
2299 _used += r->used();
2300 }
2301 return false;
2302 }
2303 size_t result() { return _used; }
2304 };
2305
2306 size_t G1CollectedHeap::recalculate_used() const {
2307 double recalculate_used_start = os::elapsedTime();
2308
2309 SumUsedClosure blk;
2310 heap_region_iterate(&blk);
2311
2312 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2313 return blk.result();
2314 }
2315
2316 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2317 switch (cause) {
2318 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2319 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2320 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2321 case GCCause::_g1_humongous_allocation: return true;
2322 case GCCause::_update_allocation_context_stats_inc: return true;
2323 case GCCause::_wb_conc_mark: return true;
2324 default: return false;
2325 }
2326 }
2327
2328 #ifndef PRODUCT
2329 void G1CollectedHeap::allocate_dummy_regions() {
2330 // Let's fill up most of the region
2331 size_t word_size = HeapRegion::GrainWords - 1024;
2332 // And as a result the region we'll allocate will be humongous.
2333 guarantee(is_humongous(word_size), "sanity");
2334
2335 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2336 // Let's use the existing mechanism for the allocation
2337 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2338 AllocationContext::system());
2339 if (dummy_obj != NULL) {
2340 MemRegion mr(dummy_obj, word_size);
2341 CollectedHeap::fill_with_object(mr);
2342 } else {
2343 // If we can't allocate once, we probably cannot allocate
2344 // again. Let's get out of the loop.
2345 break;
2346 }
2347 }
2348 }
2349 #endif // !PRODUCT
2350
2351 void G1CollectedHeap::increment_old_marking_cycles_started() {
2352 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2353 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2354 "Wrong marking cycle count (started: %d, completed: %d)",
2355 _old_marking_cycles_started, _old_marking_cycles_completed);
2356
2357 _old_marking_cycles_started++;
2358 }
2359
2360 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2361 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2362
2363 // We assume that if concurrent == true, then the caller is a
2364 // concurrent thread that was joined the Suspendible Thread
2365 // Set. If there's ever a cheap way to check this, we should add an
2366 // assert here.
2367
2368 // Given that this method is called at the end of a Full GC or of a
2369 // concurrent cycle, and those can be nested (i.e., a Full GC can
2370 // interrupt a concurrent cycle), the number of full collections
2371 // completed should be either one (in the case where there was no
2372 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2373 // behind the number of full collections started.
2374
2375 // This is the case for the inner caller, i.e. a Full GC.
2376 assert(concurrent ||
2377 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2378 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2379 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2380 "is inconsistent with _old_marking_cycles_completed = %u",
2381 _old_marking_cycles_started, _old_marking_cycles_completed);
2382
2383 // This is the case for the outer caller, i.e. the concurrent cycle.
2384 assert(!concurrent ||
2385 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2386 "for outer caller (concurrent cycle): "
2387 "_old_marking_cycles_started = %u "
2388 "is inconsistent with _old_marking_cycles_completed = %u",
2389 _old_marking_cycles_started, _old_marking_cycles_completed);
2390
2391 _old_marking_cycles_completed += 1;
2392
2393 // We need to clear the "in_progress" flag in the CM thread before
2394 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2395 // is set) so that if a waiter requests another System.gc() it doesn't
2396 // incorrectly see that a marking cycle is still in progress.
2397 if (concurrent) {
2398 _cmThread->set_idle();
2399 }
2400
2401 // This notify_all() will ensure that a thread that called
2402 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2403 // and it's waiting for a full GC to finish will be woken up. It is
2404 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2405 FullGCCount_lock->notify_all();
2406 }
2407
2408 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2409 GCIdMarkAndRestore conc_gc_id_mark;
2410 collector_state()->set_concurrent_cycle_started(true);
2411 _gc_timer_cm->register_gc_start(start_time);
2412
2413 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2414 trace_heap_before_gc(_gc_tracer_cm);
2415 _cmThread->set_gc_id(GCId::current());
2416 }
2417
2418 void G1CollectedHeap::register_concurrent_cycle_end() {
2419 if (collector_state()->concurrent_cycle_started()) {
2420 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2421 if (_cm->has_aborted()) {
2422 _gc_tracer_cm->report_concurrent_mode_failure();
2423 }
2424
2425 _gc_timer_cm->register_gc_end();
2426 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2427
2428 // Clear state variables to prepare for the next concurrent cycle.
2429 collector_state()->set_concurrent_cycle_started(false);
2430 _heap_summary_sent = false;
2431 }
2432 }
2433
2434 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2435 if (collector_state()->concurrent_cycle_started()) {
2436 // This function can be called when:
2437 // the cleanup pause is run
2438 // the concurrent cycle is aborted before the cleanup pause.
2439 // the concurrent cycle is aborted after the cleanup pause,
2440 // but before the concurrent cycle end has been registered.
2441 // Make sure that we only send the heap information once.
2442 if (!_heap_summary_sent) {
2443 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2444 trace_heap_after_gc(_gc_tracer_cm);
2445 _heap_summary_sent = true;
2446 }
2447 }
2448 }
2449
2450 void G1CollectedHeap::collect(GCCause::Cause cause) {
2451 assert_heap_not_locked();
2452
2453 uint gc_count_before;
2454 uint old_marking_count_before;
2455 uint full_gc_count_before;
2456 bool retry_gc;
2457
2458 do {
2459 retry_gc = false;
2460
2461 {
2462 MutexLocker ml(Heap_lock);
2463
2464 // Read the GC count while holding the Heap_lock
2465 gc_count_before = total_collections();
2466 full_gc_count_before = total_full_collections();
2467 old_marking_count_before = _old_marking_cycles_started;
2468 }
2469
2470 if (should_do_concurrent_full_gc(cause)) {
2471 // Schedule an initial-mark evacuation pause that will start a
2472 // concurrent cycle. We're setting word_size to 0 which means that
2473 // we are not requesting a post-GC allocation.
2474 VM_G1IncCollectionPause op(gc_count_before,
2475 0, /* word_size */
2476 true, /* should_initiate_conc_mark */
2477 g1_policy()->max_pause_time_ms(),
2478 cause);
2479 op.set_allocation_context(AllocationContext::current());
2480
2481 VMThread::execute(&op);
2482 if (!op.pause_succeeded()) {
2483 if (old_marking_count_before == _old_marking_cycles_started) {
2484 retry_gc = op.should_retry_gc();
2485 } else {
2486 // A Full GC happened while we were trying to schedule the
2487 // initial-mark GC. No point in starting a new cycle given
2488 // that the whole heap was collected anyway.
2489 }
2490
2491 if (retry_gc) {
2492 if (GC_locker::is_active_and_needs_gc()) {
2493 GC_locker::stall_until_clear();
2494 }
2495 }
2496 }
2497 } else {
2498 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2499 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2500
2501 // Schedule a standard evacuation pause. We're setting word_size
2502 // to 0 which means that we are not requesting a post-GC allocation.
2503 VM_G1IncCollectionPause op(gc_count_before,
2504 0, /* word_size */
2505 false, /* should_initiate_conc_mark */
2506 g1_policy()->max_pause_time_ms(),
2507 cause);
2508 VMThread::execute(&op);
2509 } else {
2510 // Schedule a Full GC.
2511 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2512 VMThread::execute(&op);
2513 }
2514 }
2515 } while (retry_gc);
2516 }
2517
2518 bool G1CollectedHeap::is_in(const void* p) const {
2519 if (_hrm.reserved().contains(p)) {
2520 // Given that we know that p is in the reserved space,
2521 // heap_region_containing_raw() should successfully
2522 // return the containing region.
2523 HeapRegion* hr = heap_region_containing_raw(p);
2524 return hr->is_in(p);
2525 } else {
2526 return false;
2527 }
2528 }
2529
2530 #ifdef ASSERT
2531 bool G1CollectedHeap::is_in_exact(const void* p) const {
2532 bool contains = reserved_region().contains(p);
2533 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2534 if (contains && available) {
2535 return true;
2536 } else {
2537 return false;
2538 }
2539 }
2540 #endif
2541
2542 bool G1CollectedHeap::obj_in_cs(oop obj) {
2543 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2544 return r != NULL && r->in_collection_set();
2545 }
2546
2547 // Iteration functions.
2548
2549 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2550
2551 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2552 ExtendedOopClosure* _cl;
2553 public:
2554 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2555 bool doHeapRegion(HeapRegion* r) {
2556 if (!r->is_continues_humongous()) {
2557 r->oop_iterate(_cl);
2558 }
2559 return false;
2560 }
2561 };
2562
2563 // Iterates an ObjectClosure over all objects within a HeapRegion.
2564
2565 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2566 ObjectClosure* _cl;
2567 public:
2568 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2569 bool doHeapRegion(HeapRegion* r) {
2570 if (!r->is_continues_humongous()) {
2571 r->object_iterate(_cl);
2572 }
2573 return false;
2574 }
2575 };
2576
2577 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2578 IterateObjectClosureRegionClosure blk(cl);
2579 heap_region_iterate(&blk);
2580 }
2581
2582 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2583 _hrm.iterate(cl);
2584 }
2585
2586 void
2587 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2588 uint worker_id,
2589 HeapRegionClaimer *hrclaimer,
2590 bool concurrent) const {
2591 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2592 }
2593
2594 // Clear the cached CSet starting regions and (more importantly)
2595 // the time stamps. Called when we reset the GC time stamp.
2596 void G1CollectedHeap::clear_cset_start_regions() {
2597 assert(_worker_cset_start_region != NULL, "sanity");
2598 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2599
2600 for (uint i = 0; i < ParallelGCThreads; i++) {
2601 _worker_cset_start_region[i] = NULL;
2602 _worker_cset_start_region_time_stamp[i] = 0;
2603 }
2604 }
2605
2606 // Given the id of a worker, obtain or calculate a suitable
2607 // starting region for iterating over the current collection set.
2608 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2609 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2610
2611 HeapRegion* result = NULL;
2612 unsigned gc_time_stamp = get_gc_time_stamp();
2613
2614 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2615 // Cached starting region for current worker was set
2616 // during the current pause - so it's valid.
2617 // Note: the cached starting heap region may be NULL
2618 // (when the collection set is empty).
2619 result = _worker_cset_start_region[worker_i];
2620 assert(result == NULL || result->in_collection_set(), "sanity");
2621 return result;
2622 }
2623
2624 // The cached entry was not valid so let's calculate
2625 // a suitable starting heap region for this worker.
2626
2627 // We want the parallel threads to start their collection
2628 // set iteration at different collection set regions to
2629 // avoid contention.
2630 // If we have:
2631 // n collection set regions
2632 // p threads
2633 // Then thread t will start at region floor ((t * n) / p)
2634
2635 result = g1_policy()->collection_set();
2636 uint cs_size = g1_policy()->cset_region_length();
2637 uint active_workers = workers()->active_workers();
2638
2639 uint end_ind = (cs_size * worker_i) / active_workers;
2640 uint start_ind = 0;
2641
2642 if (worker_i > 0 &&
2643 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2644 // Previous workers starting region is valid
2645 // so let's iterate from there
2646 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2647 result = _worker_cset_start_region[worker_i - 1];
2648 }
2649
2650 for (uint i = start_ind; i < end_ind; i++) {
2651 result = result->next_in_collection_set();
2652 }
2653
2654 // Note: the calculated starting heap region may be NULL
2655 // (when the collection set is empty).
2656 assert(result == NULL || result->in_collection_set(), "sanity");
2657 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2658 "should be updated only once per pause");
2659 _worker_cset_start_region[worker_i] = result;
2660 OrderAccess::storestore();
2661 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2662 return result;
2663 }
2664
2665 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2666 HeapRegion* r = g1_policy()->collection_set();
2667 while (r != NULL) {
2668 HeapRegion* next = r->next_in_collection_set();
2669 if (cl->doHeapRegion(r)) {
2670 cl->incomplete();
2671 return;
2672 }
2673 r = next;
2674 }
2675 }
2676
2677 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2678 HeapRegionClosure *cl) {
2679 if (r == NULL) {
2680 // The CSet is empty so there's nothing to do.
2681 return;
2682 }
2683
2684 assert(r->in_collection_set(),
2685 "Start region must be a member of the collection set.");
2686 HeapRegion* cur = r;
2687 while (cur != NULL) {
2688 HeapRegion* next = cur->next_in_collection_set();
2689 if (cl->doHeapRegion(cur) && false) {
2690 cl->incomplete();
2691 return;
2692 }
2693 cur = next;
2694 }
2695 cur = g1_policy()->collection_set();
2696 while (cur != r) {
2697 HeapRegion* next = cur->next_in_collection_set();
2698 if (cl->doHeapRegion(cur) && false) {
2699 cl->incomplete();
2700 return;
2701 }
2702 cur = next;
2703 }
2704 }
2705
2706 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2707 HeapRegion* result = _hrm.next_region_in_heap(from);
2708 while (result != NULL && result->is_pinned()) {
2709 result = _hrm.next_region_in_heap(result);
2710 }
2711 return result;
2712 }
2713
2714 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2715 HeapRegion* hr = heap_region_containing(addr);
2716 return hr->block_start(addr);
2717 }
2718
2719 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2720 HeapRegion* hr = heap_region_containing(addr);
2721 return hr->block_size(addr);
2722 }
2723
2724 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2725 HeapRegion* hr = heap_region_containing(addr);
2726 return hr->block_is_obj(addr);
2727 }
2728
2729 bool G1CollectedHeap::supports_tlab_allocation() const {
2730 return true;
2731 }
2732
2733 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2734 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2735 }
2736
2737 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2738 return young_list()->eden_used_bytes();
2739 }
2740
2741 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2742 // must be equal to the humongous object limit.
2743 size_t G1CollectedHeap::max_tlab_size() const {
2744 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2745 }
2746
2747 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2748 AllocationContext_t context = AllocationContext::current();
2749 return _allocator->unsafe_max_tlab_alloc(context);
2750 }
2751
2752 size_t G1CollectedHeap::max_capacity() const {
2753 return _hrm.reserved().byte_size();
2754 }
2755
2756 jlong G1CollectedHeap::millis_since_last_gc() {
2757 // assert(false, "NYI");
2758 return 0;
2759 }
2760
2761 void G1CollectedHeap::prepare_for_verify() {
2762 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2763 ensure_parsability(false);
2764 }
2765 g1_rem_set()->prepare_for_verify();
2766 }
2767
2768 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2769 VerifyOption vo) {
2770 switch (vo) {
2771 case VerifyOption_G1UsePrevMarking:
2772 return hr->obj_allocated_since_prev_marking(obj);
2773 case VerifyOption_G1UseNextMarking:
2774 return hr->obj_allocated_since_next_marking(obj);
2775 case VerifyOption_G1UseMarkWord:
2776 return false;
2777 default:
2778 ShouldNotReachHere();
2779 }
2780 return false; // keep some compilers happy
2781 }
2782
2783 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2784 switch (vo) {
2785 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2786 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2787 case VerifyOption_G1UseMarkWord: return NULL;
2788 default: ShouldNotReachHere();
2789 }
2790 return NULL; // keep some compilers happy
2791 }
2792
2793 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2794 switch (vo) {
2795 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2796 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2797 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2798 default: ShouldNotReachHere();
2799 }
2800 return false; // keep some compilers happy
2801 }
2802
2803 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2804 switch (vo) {
2805 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2806 case VerifyOption_G1UseNextMarking: return "NTAMS";
2807 case VerifyOption_G1UseMarkWord: return "NONE";
2808 default: ShouldNotReachHere();
2809 }
2810 return NULL; // keep some compilers happy
2811 }
2812
2813 class VerifyRootsClosure: public OopClosure {
2814 private:
2815 G1CollectedHeap* _g1h;
2816 VerifyOption _vo;
2817 bool _failures;
2818 public:
2819 // _vo == UsePrevMarking -> use "prev" marking information,
2820 // _vo == UseNextMarking -> use "next" marking information,
2821 // _vo == UseMarkWord -> use mark word from object header.
2822 VerifyRootsClosure(VerifyOption vo) :
2823 _g1h(G1CollectedHeap::heap()),
2824 _vo(vo),
2825 _failures(false) { }
2826
2827 bool failures() { return _failures; }
2828
2829 template <class T> void do_oop_nv(T* p) {
2830 T heap_oop = oopDesc::load_heap_oop(p);
2831 if (!oopDesc::is_null(heap_oop)) {
2832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2833 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2834 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2835 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2836 if (_vo == VerifyOption_G1UseMarkWord) {
2837 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2838 }
2839 obj->print_on(gclog_or_tty);
2840 _failures = true;
2841 }
2842 }
2843 }
2844
2845 void do_oop(oop* p) { do_oop_nv(p); }
2846 void do_oop(narrowOop* p) { do_oop_nv(p); }
2847 };
2848
2849 class G1VerifyCodeRootOopClosure: public OopClosure {
2850 G1CollectedHeap* _g1h;
2851 OopClosure* _root_cl;
2852 nmethod* _nm;
2853 VerifyOption _vo;
2854 bool _failures;
2855
2856 template <class T> void do_oop_work(T* p) {
2857 // First verify that this root is live
2858 _root_cl->do_oop(p);
2859
2860 if (!G1VerifyHeapRegionCodeRoots) {
2861 // We're not verifying the code roots attached to heap region.
2862 return;
2863 }
2864
2865 // Don't check the code roots during marking verification in a full GC
2866 if (_vo == VerifyOption_G1UseMarkWord) {
2867 return;
2868 }
2869
2870 // Now verify that the current nmethod (which contains p) is
2871 // in the code root list of the heap region containing the
2872 // object referenced by p.
2873
2874 T heap_oop = oopDesc::load_heap_oop(p);
2875 if (!oopDesc::is_null(heap_oop)) {
2876 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2877
2878 // Now fetch the region containing the object
2879 HeapRegion* hr = _g1h->heap_region_containing(obj);
2880 HeapRegionRemSet* hrrs = hr->rem_set();
2881 // Verify that the strong code root list for this region
2882 // contains the nmethod
2883 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2884 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2885 "from nmethod " PTR_FORMAT " not in strong "
2886 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2887 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2888 _failures = true;
2889 }
2890 }
2891 }
2892
2893 public:
2894 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2895 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2896
2897 void do_oop(oop* p) { do_oop_work(p); }
2898 void do_oop(narrowOop* p) { do_oop_work(p); }
2899
2900 void set_nmethod(nmethod* nm) { _nm = nm; }
2901 bool failures() { return _failures; }
2902 };
2903
2904 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2905 G1VerifyCodeRootOopClosure* _oop_cl;
2906
2907 public:
2908 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2909 _oop_cl(oop_cl) {}
2910
2911 void do_code_blob(CodeBlob* cb) {
2912 nmethod* nm = cb->as_nmethod_or_null();
2913 if (nm != NULL) {
2914 _oop_cl->set_nmethod(nm);
2915 nm->oops_do(_oop_cl);
2916 }
2917 }
2918 };
2919
2920 class YoungRefCounterClosure : public OopClosure {
2921 G1CollectedHeap* _g1h;
2922 int _count;
2923 public:
2924 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2925 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2926 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2927
2928 int count() { return _count; }
2929 void reset_count() { _count = 0; };
2930 };
2931
2932 class VerifyKlassClosure: public KlassClosure {
2933 YoungRefCounterClosure _young_ref_counter_closure;
2934 OopClosure *_oop_closure;
2935 public:
2936 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2937 void do_klass(Klass* k) {
2938 k->oops_do(_oop_closure);
2939
2940 _young_ref_counter_closure.reset_count();
2941 k->oops_do(&_young_ref_counter_closure);
2942 if (_young_ref_counter_closure.count() > 0) {
2943 guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));
2944 }
2945 }
2946 };
2947
2948 class VerifyLivenessOopClosure: public OopClosure {
2949 G1CollectedHeap* _g1h;
2950 VerifyOption _vo;
2951 public:
2952 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2953 _g1h(g1h), _vo(vo)
2954 { }
2955 void do_oop(narrowOop *p) { do_oop_work(p); }
2956 void do_oop( oop *p) { do_oop_work(p); }
2957
2958 template <class T> void do_oop_work(T *p) {
2959 oop obj = oopDesc::load_decode_heap_oop(p);
2960 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2961 "Dead object referenced by a not dead object");
2962 }
2963 };
2964
2965 class VerifyObjsInRegionClosure: public ObjectClosure {
2966 private:
2967 G1CollectedHeap* _g1h;
2968 size_t _live_bytes;
2969 HeapRegion *_hr;
2970 VerifyOption _vo;
2971 public:
2972 // _vo == UsePrevMarking -> use "prev" marking information,
2973 // _vo == UseNextMarking -> use "next" marking information,
2974 // _vo == UseMarkWord -> use mark word from object header.
2975 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2976 : _live_bytes(0), _hr(hr), _vo(vo) {
2977 _g1h = G1CollectedHeap::heap();
2978 }
2979 void do_object(oop o) {
2980 VerifyLivenessOopClosure isLive(_g1h, _vo);
2981 assert(o != NULL, "Huh?");
2982 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2983 // If the object is alive according to the mark word,
2984 // then verify that the marking information agrees.
2985 // Note we can't verify the contra-positive of the
2986 // above: if the object is dead (according to the mark
2987 // word), it may not be marked, or may have been marked
2988 // but has since became dead, or may have been allocated
2989 // since the last marking.
2990 if (_vo == VerifyOption_G1UseMarkWord) {
2991 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2992 }
2993
2994 o->oop_iterate_no_header(&isLive);
2995 if (!_hr->obj_allocated_since_prev_marking(o)) {
2996 size_t obj_size = o->size(); // Make sure we don't overflow
2997 _live_bytes += (obj_size * HeapWordSize);
2998 }
2999 }
3000 }
3001 size_t live_bytes() { return _live_bytes; }
3002 };
3003
3004 class VerifyArchiveOopClosure: public OopClosure {
3005 public:
3006 VerifyArchiveOopClosure(HeapRegion *hr) { }
3007 void do_oop(narrowOop *p) { do_oop_work(p); }
3008 void do_oop( oop *p) { do_oop_work(p); }
3009
3010 template <class T> void do_oop_work(T *p) {
3011 oop obj = oopDesc::load_decode_heap_oop(p);
3012 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3013 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3014 p2i(p), p2i(obj));
3015 }
3016 };
3017
3018 class VerifyArchiveRegionClosure: public ObjectClosure {
3019 public:
3020 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3021 // Verify that all object pointers are to archive regions.
3022 void do_object(oop o) {
3023 VerifyArchiveOopClosure checkOop(NULL);
3024 assert(o != NULL, "Should not be here for NULL oops");
3025 o->oop_iterate_no_header(&checkOop);
3026 }
3027 };
3028
3029 class VerifyRegionClosure: public HeapRegionClosure {
3030 private:
3031 bool _par;
3032 VerifyOption _vo;
3033 bool _failures;
3034 public:
3035 // _vo == UsePrevMarking -> use "prev" marking information,
3036 // _vo == UseNextMarking -> use "next" marking information,
3037 // _vo == UseMarkWord -> use mark word from object header.
3038 VerifyRegionClosure(bool par, VerifyOption vo)
3039 : _par(par),
3040 _vo(vo),
3041 _failures(false) {}
3042
3043 bool failures() {
3044 return _failures;
3045 }
3046
3047 bool doHeapRegion(HeapRegion* r) {
3048 // For archive regions, verify there are no heap pointers to
3049 // non-pinned regions. For all others, verify liveness info.
3050 if (r->is_archive()) {
3051 VerifyArchiveRegionClosure verify_oop_pointers(r);
3052 r->object_iterate(&verify_oop_pointers);
3053 return true;
3054 }
3055 if (!r->is_continues_humongous()) {
3056 bool failures = false;
3057 r->verify(_vo, &failures);
3058 if (failures) {
3059 _failures = true;
3060 } else {
3061 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3062 r->object_iterate(¬_dead_yet_cl);
3063 if (_vo != VerifyOption_G1UseNextMarking) {
3064 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3065 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3066 "max_live_bytes " SIZE_FORMAT " "
3067 "< calculated " SIZE_FORMAT,
3068 p2i(r->bottom()), p2i(r->end()),
3069 r->max_live_bytes(),
3070 not_dead_yet_cl.live_bytes());
3071 _failures = true;
3072 }
3073 } else {
3074 // When vo == UseNextMarking we cannot currently do a sanity
3075 // check on the live bytes as the calculation has not been
3076 // finalized yet.
3077 }
3078 }
3079 }
3080 return false; // stop the region iteration if we hit a failure
3081 }
3082 };
3083
3084 // This is the task used for parallel verification of the heap regions
3085
3086 class G1ParVerifyTask: public AbstractGangTask {
3087 private:
3088 G1CollectedHeap* _g1h;
3089 VerifyOption _vo;
3090 bool _failures;
3091 HeapRegionClaimer _hrclaimer;
3092
3093 public:
3094 // _vo == UsePrevMarking -> use "prev" marking information,
3095 // _vo == UseNextMarking -> use "next" marking information,
3096 // _vo == UseMarkWord -> use mark word from object header.
3097 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3098 AbstractGangTask("Parallel verify task"),
3099 _g1h(g1h),
3100 _vo(vo),
3101 _failures(false),
3102 _hrclaimer(g1h->workers()->active_workers()) {}
3103
3104 bool failures() {
3105 return _failures;
3106 }
3107
3108 void work(uint worker_id) {
3109 HandleMark hm;
3110 VerifyRegionClosure blk(true, _vo);
3111 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3112 if (blk.failures()) {
3113 _failures = true;
3114 }
3115 }
3116 };
3117
3118 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3119 if (SafepointSynchronize::is_at_safepoint()) {
3120 assert(Thread::current()->is_VM_thread(),
3121 "Expected to be executed serially by the VM thread at this point");
3122
3123 if (!silent) { gclog_or_tty->print("Roots "); }
3124 VerifyRootsClosure rootsCl(vo);
3125 VerifyKlassClosure klassCl(this, &rootsCl);
3126 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3127
3128 // We apply the relevant closures to all the oops in the
3129 // system dictionary, class loader data graph, the string table
3130 // and the nmethods in the code cache.
3131 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3132 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3133
3134 {
3135 G1RootProcessor root_processor(this, 1);
3136 root_processor.process_all_roots(&rootsCl,
3137 &cldCl,
3138 &blobsCl);
3139 }
3140
3141 bool failures = rootsCl.failures() || codeRootsCl.failures();
3142
3143 if (vo != VerifyOption_G1UseMarkWord) {
3144 // If we're verifying during a full GC then the region sets
3145 // will have been torn down at the start of the GC. Therefore
3146 // verifying the region sets will fail. So we only verify
3147 // the region sets when not in a full GC.
3148 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3149 verify_region_sets();
3150 }
3151
3152 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3153 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3154
3155 G1ParVerifyTask task(this, vo);
3156 workers()->run_task(&task);
3157 if (task.failures()) {
3158 failures = true;
3159 }
3160
3161 } else {
3162 VerifyRegionClosure blk(false, vo);
3163 heap_region_iterate(&blk);
3164 if (blk.failures()) {
3165 failures = true;
3166 }
3167 }
3168
3169 if (G1StringDedup::is_enabled()) {
3170 if (!silent) gclog_or_tty->print("StrDedup ");
3171 G1StringDedup::verify();
3172 }
3173
3174 if (failures) {
3175 gclog_or_tty->print_cr("Heap:");
3176 // It helps to have the per-region information in the output to
3177 // help us track down what went wrong. This is why we call
3178 // print_extended_on() instead of print_on().
3179 print_extended_on(gclog_or_tty);
3180 gclog_or_tty->cr();
3181 gclog_or_tty->flush();
3182 }
3183 guarantee(!failures, "there should not have been any failures");
3184 } else {
3185 if (!silent) {
3186 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3187 if (G1StringDedup::is_enabled()) {
3188 gclog_or_tty->print(", StrDedup");
3189 }
3190 gclog_or_tty->print(") ");
3191 }
3192 }
3193 }
3194
3195 void G1CollectedHeap::verify(bool silent) {
3196 verify(silent, VerifyOption_G1UsePrevMarking);
3197 }
3198
3199 double G1CollectedHeap::verify(bool guard, const char* msg) {
3200 double verify_time_ms = 0.0;
3201
3202 if (guard && total_collections() >= VerifyGCStartAt) {
3203 double verify_start = os::elapsedTime();
3204 HandleMark hm; // Discard invalid handles created during verification
3205 prepare_for_verify();
3206 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3207 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3208 }
3209
3210 return verify_time_ms;
3211 }
3212
3213 void G1CollectedHeap::verify_before_gc() {
3214 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3215 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3216 }
3217
3218 void G1CollectedHeap::verify_after_gc() {
3219 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3220 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3221 }
3222
3223 class PrintRegionClosure: public HeapRegionClosure {
3224 outputStream* _st;
3225 public:
3226 PrintRegionClosure(outputStream* st) : _st(st) {}
3227 bool doHeapRegion(HeapRegion* r) {
3228 r->print_on(_st);
3229 return false;
3230 }
3231 };
3232
3233 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3234 const HeapRegion* hr,
3235 const VerifyOption vo) const {
3236 switch (vo) {
3237 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3238 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3239 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3240 default: ShouldNotReachHere();
3241 }
3242 return false; // keep some compilers happy
3243 }
3244
3245 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3246 const VerifyOption vo) const {
3247 switch (vo) {
3248 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3249 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3250 case VerifyOption_G1UseMarkWord: {
3251 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3252 return !obj->is_gc_marked() && !hr->is_archive();
3253 }
3254 default: ShouldNotReachHere();
3255 }
3256 return false; // keep some compilers happy
3257 }
3258
3259 void G1CollectedHeap::print_on(outputStream* st) const {
3260 st->print(" %-20s", "garbage-first heap");
3261 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3262 capacity()/K, used_unlocked()/K);
3263 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3264 p2i(_hrm.reserved().start()),
3265 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3266 p2i(_hrm.reserved().end()));
3267 st->cr();
3268 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3269 uint young_regions = _young_list->length();
3270 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3271 (size_t) young_regions * HeapRegion::GrainBytes / K);
3272 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3273 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3274 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3275 st->cr();
3276 MetaspaceAux::print_on(st);
3277 }
3278
3279 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3280 print_on(st);
3281
3282 // Print the per-region information.
3283 st->cr();
3284 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3285 "HS=humongous(starts), HC=humongous(continues), "
3286 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3287 "PTAMS=previous top-at-mark-start, "
3288 "NTAMS=next top-at-mark-start)");
3289 PrintRegionClosure blk(st);
3290 heap_region_iterate(&blk);
3291 }
3292
3293 void G1CollectedHeap::print_on_error(outputStream* st) const {
3294 this->CollectedHeap::print_on_error(st);
3295
3296 if (_cm != NULL) {
3297 st->cr();
3298 _cm->print_on_error(st);
3299 }
3300 }
3301
3302 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3303 workers()->print_worker_threads_on(st);
3304 _cmThread->print_on(st);
3305 st->cr();
3306 _cm->print_worker_threads_on(st);
3307 _cg1r->print_worker_threads_on(st);
3308 if (G1StringDedup::is_enabled()) {
3309 G1StringDedup::print_worker_threads_on(st);
3310 }
3311 }
3312
3313 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3314 workers()->threads_do(tc);
3315 tc->do_thread(_cmThread);
3316 _cg1r->threads_do(tc);
3317 if (G1StringDedup::is_enabled()) {
3318 G1StringDedup::threads_do(tc);
3319 }
3320 }
3321
3322 void G1CollectedHeap::print_tracing_info() const {
3323 // We'll overload this to mean "trace GC pause statistics."
3324 if (TraceYoungGenTime || TraceOldGenTime) {
3325 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3326 // to that.
3327 g1_policy()->print_tracing_info();
3328 }
3329 if (G1SummarizeRSetStats) {
3330 g1_rem_set()->print_summary_info();
3331 }
3332 if (G1SummarizeConcMark) {
3333 concurrent_mark()->print_summary_info();
3334 }
3335 g1_policy()->print_yg_surv_rate_info();
3336 }
3337
3338 #ifndef PRODUCT
3339 // Helpful for debugging RSet issues.
3340
3341 class PrintRSetsClosure : public HeapRegionClosure {
3342 private:
3343 const char* _msg;
3344 size_t _occupied_sum;
3345
3346 public:
3347 bool doHeapRegion(HeapRegion* r) {
3348 HeapRegionRemSet* hrrs = r->rem_set();
3349 size_t occupied = hrrs->occupied();
3350 _occupied_sum += occupied;
3351
3352 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3353 HR_FORMAT_PARAMS(r));
3354 if (occupied == 0) {
3355 gclog_or_tty->print_cr(" RSet is empty");
3356 } else {
3357 hrrs->print();
3358 }
3359 gclog_or_tty->print_cr("----------");
3360 return false;
3361 }
3362
3363 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3364 gclog_or_tty->cr();
3365 gclog_or_tty->print_cr("========================================");
3366 gclog_or_tty->print_cr("%s", msg);
3367 gclog_or_tty->cr();
3368 }
3369
3370 ~PrintRSetsClosure() {
3371 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3372 gclog_or_tty->print_cr("========================================");
3373 gclog_or_tty->cr();
3374 }
3375 };
3376
3377 void G1CollectedHeap::print_cset_rsets() {
3378 PrintRSetsClosure cl("Printing CSet RSets");
3379 collection_set_iterate(&cl);
3380 }
3381
3382 void G1CollectedHeap::print_all_rsets() {
3383 PrintRSetsClosure cl("Printing All RSets");;
3384 heap_region_iterate(&cl);
3385 }
3386 #endif // PRODUCT
3387
3388 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3389 YoungList* young_list = heap()->young_list();
3390
3391 size_t eden_used_bytes = young_list->eden_used_bytes();
3392 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3393
3394 size_t eden_capacity_bytes =
3395 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3396
3397 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3398 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3399 }
3400
3401 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
3402 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
3403 stats->unused(), stats->used(), stats->region_end_waste(),
3404 stats->regions_filled(), stats->direct_allocated(),
3405 stats->failure_used(), stats->failure_waste());
3406 }
3407
3408 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3409 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3410 gc_tracer->report_gc_heap_summary(when, heap_summary);
3411
3412 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3413 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3414 }
3415
3416
3417 G1CollectedHeap* G1CollectedHeap::heap() {
3418 CollectedHeap* heap = Universe::heap();
3419 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3420 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3421 return (G1CollectedHeap*)heap;
3422 }
3423
3424 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3425 // always_do_update_barrier = false;
3426 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3427 // Fill TLAB's and such
3428 accumulate_statistics_all_tlabs();
3429 ensure_parsability(true);
3430
3431 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3432 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3433 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3434 }
3435 }
3436
3437 void G1CollectedHeap::gc_epilogue(bool full) {
3438
3439 if (G1SummarizeRSetStats &&
3440 (G1SummarizeRSetStatsPeriod > 0) &&
3441 // we are at the end of the GC. Total collections has already been increased.
3442 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3443 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3444 }
3445
3446 // FIXME: what is this about?
3447 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3448 // is set.
3449 #if defined(COMPILER2) || INCLUDE_JVMCI
3450 assert(DerivedPointerTable::is_empty(), "derived pointer present");
3451 #endif
3452 // always_do_update_barrier = true;
3453
3454 resize_all_tlabs();
3455 allocation_context_stats().update(full);
3456
3457 // We have just completed a GC. Update the soft reference
3458 // policy with the new heap occupancy
3459 Universe::update_heap_info_at_gc();
3460 }
3461
3462 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3463 uint gc_count_before,
3464 bool* succeeded,
3465 GCCause::Cause gc_cause) {
3466 assert_heap_not_locked_and_not_at_safepoint();
3467 g1_policy()->record_stop_world_start();
3468 VM_G1IncCollectionPause op(gc_count_before,
3469 word_size,
3470 false, /* should_initiate_conc_mark */
3471 g1_policy()->max_pause_time_ms(),
3472 gc_cause);
3473
3474 op.set_allocation_context(AllocationContext::current());
3475 VMThread::execute(&op);
3476
3477 HeapWord* result = op.result();
3478 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3479 assert(result == NULL || ret_succeeded,
3480 "the result should be NULL if the VM did not succeed");
3481 *succeeded = ret_succeeded;
3482
3483 assert_heap_not_locked();
3484 return result;
3485 }
3486
3487 void
3488 G1CollectedHeap::doConcurrentMark() {
3489 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3490 if (!_cmThread->in_progress()) {
3491 _cmThread->set_started();
3492 CGC_lock->notify();
3493 }
3494 }
3495
3496 size_t G1CollectedHeap::pending_card_num() {
3497 size_t extra_cards = 0;
3498 JavaThread *curr = Threads::first();
3499 while (curr != NULL) {
3500 DirtyCardQueue& dcq = curr->dirty_card_queue();
3501 extra_cards += dcq.size();
3502 curr = curr->next();
3503 }
3504 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3505 size_t buffer_size = dcqs.buffer_size();
3506 size_t buffer_num = dcqs.completed_buffers_num();
3507
3508 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3509 // in bytes - not the number of 'entries'. We need to convert
3510 // into a number of cards.
3511 return (buffer_size * buffer_num + extra_cards) / oopSize;
3512 }
3513
3514 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3515 private:
3516 size_t _total_humongous;
3517 size_t _candidate_humongous;
3518
3519 DirtyCardQueue _dcq;
3520
3521 // We don't nominate objects with many remembered set entries, on
3522 // the assumption that such objects are likely still live.
3523 bool is_remset_small(HeapRegion* region) const {
3524 HeapRegionRemSet* const rset = region->rem_set();
3525 return G1EagerReclaimHumongousObjectsWithStaleRefs
3526 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3527 : rset->is_empty();
3528 }
3529
3530 bool is_typeArray_region(HeapRegion* region) const {
3531 return oop(region->bottom())->is_typeArray();
3532 }
3533
3534 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3535 assert(region->is_starts_humongous(), "Must start a humongous object");
3536
3537 // Candidate selection must satisfy the following constraints
3538 // while concurrent marking is in progress:
3539 //
3540 // * In order to maintain SATB invariants, an object must not be
3541 // reclaimed if it was allocated before the start of marking and
3542 // has not had its references scanned. Such an object must have
3543 // its references (including type metadata) scanned to ensure no
3544 // live objects are missed by the marking process. Objects
3545 // allocated after the start of concurrent marking don't need to
3546 // be scanned.
3547 //
3548 // * An object must not be reclaimed if it is on the concurrent
3549 // mark stack. Objects allocated after the start of concurrent
3550 // marking are never pushed on the mark stack.
3551 //
3552 // Nominating only objects allocated after the start of concurrent
3553 // marking is sufficient to meet both constraints. This may miss
3554 // some objects that satisfy the constraints, but the marking data
3555 // structures don't support efficiently performing the needed
3556 // additional tests or scrubbing of the mark stack.
3557 //
3558 // However, we presently only nominate is_typeArray() objects.
3559 // A humongous object containing references induces remembered
3560 // set entries on other regions. In order to reclaim such an
3561 // object, those remembered sets would need to be cleaned up.
3562 //
3563 // We also treat is_typeArray() objects specially, allowing them
3564 // to be reclaimed even if allocated before the start of
3565 // concurrent mark. For this we rely on mark stack insertion to
3566 // exclude is_typeArray() objects, preventing reclaiming an object
3567 // that is in the mark stack. We also rely on the metadata for
3568 // such objects to be built-in and so ensured to be kept live.
3569 // Frequent allocation and drop of large binary blobs is an
3570 // important use case for eager reclaim, and this special handling
3571 // may reduce needed headroom.
3572
3573 return is_typeArray_region(region) && is_remset_small(region);
3574 }
3575
3576 public:
3577 RegisterHumongousWithInCSetFastTestClosure()
3578 : _total_humongous(0),
3579 _candidate_humongous(0),
3580 _dcq(&JavaThread::dirty_card_queue_set()) {
3581 }
3582
3583 virtual bool doHeapRegion(HeapRegion* r) {
3584 if (!r->is_starts_humongous()) {
3585 return false;
3586 }
3587 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3588
3589 bool is_candidate = humongous_region_is_candidate(g1h, r);
3590 uint rindex = r->hrm_index();
3591 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3592 if (is_candidate) {
3593 _candidate_humongous++;
3594 g1h->register_humongous_region_with_cset(rindex);
3595 // Is_candidate already filters out humongous object with large remembered sets.
3596 // If we have a humongous object with a few remembered sets, we simply flush these
3597 // remembered set entries into the DCQS. That will result in automatic
3598 // re-evaluation of their remembered set entries during the following evacuation
3599 // phase.
3600 if (!r->rem_set()->is_empty()) {
3601 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3602 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3603 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3604 HeapRegionRemSetIterator hrrs(r->rem_set());
3605 size_t card_index;
3606 while (hrrs.has_next(card_index)) {
3607 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3608 // The remembered set might contain references to already freed
3609 // regions. Filter out such entries to avoid failing card table
3610 // verification.
3611 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3612 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3613 *card_ptr = CardTableModRefBS::dirty_card_val();
3614 _dcq.enqueue(card_ptr);
3615 }
3616 }
3617 }
3618 r->rem_set()->clear_locked();
3619 }
3620 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3621 }
3622 _total_humongous++;
3623
3624 return false;
3625 }
3626
3627 size_t total_humongous() const { return _total_humongous; }
3628 size_t candidate_humongous() const { return _candidate_humongous; }
3629
3630 void flush_rem_set_entries() { _dcq.flush(); }
3631 };
3632
3633 void G1CollectedHeap::register_humongous_regions_with_cset() {
3634 if (!G1EagerReclaimHumongousObjects) {
3635 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3636 return;
3637 }
3638 double time = os::elapsed_counter();
3639
3640 // Collect reclaim candidate information and register candidates with cset.
3641 RegisterHumongousWithInCSetFastTestClosure cl;
3642 heap_region_iterate(&cl);
3643
3644 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3645 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3646 cl.total_humongous(),
3647 cl.candidate_humongous());
3648 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3649
3650 // Finally flush all remembered set entries to re-check into the global DCQS.
3651 cl.flush_rem_set_entries();
3652 }
3653
3654 #ifdef ASSERT
3655 class VerifyCSetClosure: public HeapRegionClosure {
3656 public:
3657 bool doHeapRegion(HeapRegion* hr) {
3658 // Here we check that the CSet region's RSet is ready for parallel
3659 // iteration. The fields that we'll verify are only manipulated
3660 // when the region is part of a CSet and is collected. Afterwards,
3661 // we reset these fields when we clear the region's RSet (when the
3662 // region is freed) so they are ready when the region is
3663 // re-allocated. The only exception to this is if there's an
3664 // evacuation failure and instead of freeing the region we leave
3665 // it in the heap. In that case, we reset these fields during
3666 // evacuation failure handling.
3667 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3668
3669 // Here's a good place to add any other checks we'd like to
3670 // perform on CSet regions.
3671 return false;
3672 }
3673 };
3674 #endif // ASSERT
3675
3676 uint G1CollectedHeap::num_task_queues() const {
3677 return _task_queues->size();
3678 }
3679
3680 #if TASKQUEUE_STATS
3681 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3682 st->print_raw_cr("GC Task Stats");
3683 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3684 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3685 }
3686
3687 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3688 print_taskqueue_stats_hdr(st);
3689
3690 TaskQueueStats totals;
3691 const uint n = num_task_queues();
3692 for (uint i = 0; i < n; ++i) {
3693 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3694 totals += task_queue(i)->stats;
3695 }
3696 st->print_raw("tot "); totals.print(st); st->cr();
3697
3698 DEBUG_ONLY(totals.verify());
3699 }
3700
3701 void G1CollectedHeap::reset_taskqueue_stats() {
3702 const uint n = num_task_queues();
3703 for (uint i = 0; i < n; ++i) {
3704 task_queue(i)->stats.reset();
3705 }
3706 }
3707 #endif // TASKQUEUE_STATS
3708
3709 void G1CollectedHeap::log_gc_header() {
3710 if (!G1Log::fine()) {
3711 return;
3712 }
3713
3714 gclog_or_tty->gclog_stamp();
3715
3716 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3717 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3718 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3719
3720 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3721 }
3722
3723 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3724 if (!G1Log::fine()) {
3725 return;
3726 }
3727
3728 if (G1Log::finer()) {
3729 if (evacuation_failed()) {
3730 gclog_or_tty->print(" (to-space exhausted)");
3731 }
3732 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3733 g1_policy()->print_phases(pause_time_sec);
3734 g1_policy()->print_detailed_heap_transition();
3735 } else {
3736 if (evacuation_failed()) {
3737 gclog_or_tty->print("--");
3738 }
3739 g1_policy()->print_heap_transition();
3740 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3741 }
3742 gclog_or_tty->flush();
3743 }
3744
3745 void G1CollectedHeap::wait_for_root_region_scanning() {
3746 double scan_wait_start = os::elapsedTime();
3747 // We have to wait until the CM threads finish scanning the
3748 // root regions as it's the only way to ensure that all the
3749 // objects on them have been correctly scanned before we start
3750 // moving them during the GC.
3751 bool waited = _cm->root_regions()->wait_until_scan_finished();
3752 double wait_time_ms = 0.0;
3753 if (waited) {
3754 double scan_wait_end = os::elapsedTime();
3755 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3756 }
3757 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3758 }
3759
3760 bool
3761 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3762 assert_at_safepoint(true /* should_be_vm_thread */);
3763 guarantee(!is_gc_active(), "collection is not reentrant");
3764
3765 if (GC_locker::check_active_before_gc()) {
3766 return false;
3767 }
3768
3769 _gc_timer_stw->register_gc_start();
3770
3771 GCIdMark gc_id_mark;
3772 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3773
3774 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3775 ResourceMark rm;
3776
3777 wait_for_root_region_scanning();
3778
3779 G1Log::update_level();
3780 print_heap_before_gc();
3781 trace_heap_before_gc(_gc_tracer_stw);
3782
3783 verify_region_sets_optional();
3784 verify_dirty_young_regions();
3785
3786 // This call will decide whether this pause is an initial-mark
3787 // pause. If it is, during_initial_mark_pause() will return true
3788 // for the duration of this pause.
3789 g1_policy()->decide_on_conc_mark_initiation();
3790
3791 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3792 assert(!collector_state()->during_initial_mark_pause() ||
3793 collector_state()->gcs_are_young(), "sanity");
3794
3795 // We also do not allow mixed GCs during marking.
3796 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3797
3798 // Record whether this pause is an initial mark. When the current
3799 // thread has completed its logging output and it's safe to signal
3800 // the CM thread, the flag's value in the policy has been reset.
3801 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3802
3803 // Inner scope for scope based logging, timers, and stats collection
3804 {
3805 EvacuationInfo evacuation_info;
3806
3807 if (collector_state()->during_initial_mark_pause()) {
3808 // We are about to start a marking cycle, so we increment the
3809 // full collection counter.
3810 increment_old_marking_cycles_started();
3811 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3812 }
3813
3814 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3815
3816 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3817
3818 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3819 workers()->active_workers(),
3820 Threads::number_of_non_daemon_threads());
3821 workers()->set_active_workers(active_workers);
3822
3823 double pause_start_sec = os::elapsedTime();
3824 g1_policy()->note_gc_start(active_workers);
3825 log_gc_header();
3826
3827 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3828 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3829
3830 // If the secondary_free_list is not empty, append it to the
3831 // free_list. No need to wait for the cleanup operation to finish;
3832 // the region allocation code will check the secondary_free_list
3833 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3834 // set, skip this step so that the region allocation code has to
3835 // get entries from the secondary_free_list.
3836 if (!G1StressConcRegionFreeing) {
3837 append_secondary_free_list_if_not_empty_with_lock();
3838 }
3839
3840 assert(check_young_list_well_formed(), "young list should be well formed");
3841
3842 // Don't dynamically change the number of GC threads this early. A value of
3843 // 0 is used to indicate serial work. When parallel work is done,
3844 // it will be set.
3845
3846 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3847 IsGCActiveMark x;
3848
3849 gc_prologue(false);
3850 increment_total_collections(false /* full gc */);
3851 increment_gc_time_stamp();
3852
3853 verify_before_gc();
3854
3855 check_bitmaps("GC Start");
3856
3857 #if defined(COMPILER2) || INCLUDE_JVMCI
3858 DerivedPointerTable::clear();
3859 #endif
3860
3861 // Please see comment in g1CollectedHeap.hpp and
3862 // G1CollectedHeap::ref_processing_init() to see how
3863 // reference processing currently works in G1.
3864
3865 // Enable discovery in the STW reference processor
3866 ref_processor_stw()->enable_discovery();
3867
3868 {
3869 // We want to temporarily turn off discovery by the
3870 // CM ref processor, if necessary, and turn it back on
3871 // on again later if we do. Using a scoped
3872 // NoRefDiscovery object will do this.
3873 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3874
3875 // Forget the current alloc region (we might even choose it to be part
3876 // of the collection set!).
3877 _allocator->release_mutator_alloc_region();
3878
3879 // We should call this after we retire the mutator alloc
3880 // region(s) so that all the ALLOC / RETIRE events are generated
3881 // before the start GC event.
3882 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3883
3884 // This timing is only used by the ergonomics to handle our pause target.
3885 // It is unclear why this should not include the full pause. We will
3886 // investigate this in CR 7178365.
3887 //
3888 // Preserving the old comment here if that helps the investigation:
3889 //
3890 // The elapsed time induced by the start time below deliberately elides
3891 // the possible verification above.
3892 double sample_start_time_sec = os::elapsedTime();
3893
3894 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3895
3896 if (collector_state()->during_initial_mark_pause()) {
3897 concurrent_mark()->checkpointRootsInitialPre();
3898 }
3899
3900 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3901 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3902
3903 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3904
3905 register_humongous_regions_with_cset();
3906
3907 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3908
3909 _cm->note_start_of_gc();
3910 // We call this after finalize_cset() to
3911 // ensure that the CSet has been finalized.
3912 _cm->verify_no_cset_oops();
3913
3914 if (_hr_printer.is_active()) {
3915 HeapRegion* hr = g1_policy()->collection_set();
3916 while (hr != NULL) {
3917 _hr_printer.cset(hr);
3918 hr = hr->next_in_collection_set();
3919 }
3920 }
3921
3922 #ifdef ASSERT
3923 VerifyCSetClosure cl;
3924 collection_set_iterate(&cl);
3925 #endif // ASSERT
3926
3927 // Initialize the GC alloc regions.
3928 _allocator->init_gc_alloc_regions(evacuation_info);
3929
3930 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3931 pre_evacuate_collection_set();
3932
3933 // Actually do the work...
3934 evacuate_collection_set(evacuation_info, &per_thread_states);
3935
3936 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3937
3938 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3939 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3940
3941 eagerly_reclaim_humongous_regions();
3942
3943 g1_policy()->clear_collection_set();
3944
3945 // Start a new incremental collection set for the next pause.
3946 g1_policy()->start_incremental_cset_building();
3947
3948 clear_cset_fast_test();
3949
3950 _young_list->reset_sampled_info();
3951
3952 // Don't check the whole heap at this point as the
3953 // GC alloc regions from this pause have been tagged
3954 // as survivors and moved on to the survivor list.
3955 // Survivor regions will fail the !is_young() check.
3956 assert(check_young_list_empty(false /* check_heap */),
3957 "young list should be empty");
3958
3959 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3960 _young_list->first_survivor_region(),
3961 _young_list->last_survivor_region());
3962
3963 _young_list->reset_auxilary_lists();
3964
3965 if (evacuation_failed()) {
3966 set_used(recalculate_used());
3967 if (_archive_allocator != NULL) {
3968 _archive_allocator->clear_used();
3969 }
3970 for (uint i = 0; i < ParallelGCThreads; i++) {
3971 if (_evacuation_failed_info_array[i].has_failed()) {
3972 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3973 }
3974 }
3975 } else {
3976 // The "used" of the the collection set have already been subtracted
3977 // when they were freed. Add in the bytes evacuated.
3978 increase_used(g1_policy()->bytes_copied_during_gc());
3979 }
3980
3981 if (collector_state()->during_initial_mark_pause()) {
3982 // We have to do this before we notify the CM threads that
3983 // they can start working to make sure that all the
3984 // appropriate initialization is done on the CM object.
3985 concurrent_mark()->checkpointRootsInitialPost();
3986 collector_state()->set_mark_in_progress(true);
3987 // Note that we don't actually trigger the CM thread at
3988 // this point. We do that later when we're sure that
3989 // the current thread has completed its logging output.
3990 }
3991
3992 allocate_dummy_regions();
3993
3994 _allocator->init_mutator_alloc_region();
3995
3996 {
3997 size_t expand_bytes = g1_policy()->expansion_amount();
3998 if (expand_bytes > 0) {
3999 size_t bytes_before = capacity();
4000 // No need for an ergo verbose message here,
4001 // expansion_amount() does this when it returns a value > 0.
4002 double expand_ms;
4003 if (!expand(expand_bytes, &expand_ms)) {
4004 // We failed to expand the heap. Cannot do anything about it.
4005 }
4006 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
4007 }
4008 }
4009
4010 // We redo the verification but now wrt to the new CSet which
4011 // has just got initialized after the previous CSet was freed.
4012 _cm->verify_no_cset_oops();
4013 _cm->note_end_of_gc();
4014
4015 // This timing is only used by the ergonomics to handle our pause target.
4016 // It is unclear why this should not include the full pause. We will
4017 // investigate this in CR 7178365.
4018 double sample_end_time_sec = os::elapsedTime();
4019 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4020 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
4021 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
4022
4023 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
4024 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
4025
4026 MemoryService::track_memory_usage();
4027
4028 // In prepare_for_verify() below we'll need to scan the deferred
4029 // update buffers to bring the RSets up-to-date if
4030 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4031 // the update buffers we'll probably need to scan cards on the
4032 // regions we just allocated to (i.e., the GC alloc
4033 // regions). However, during the last GC we called
4034 // set_saved_mark() on all the GC alloc regions, so card
4035 // scanning might skip the [saved_mark_word()...top()] area of
4036 // those regions (i.e., the area we allocated objects into
4037 // during the last GC). But it shouldn't. Given that
4038 // saved_mark_word() is conditional on whether the GC time stamp
4039 // on the region is current or not, by incrementing the GC time
4040 // stamp here we invalidate all the GC time stamps on all the
4041 // regions and saved_mark_word() will simply return top() for
4042 // all the regions. This is a nicer way of ensuring this rather
4043 // than iterating over the regions and fixing them. In fact, the
4044 // GC time stamp increment here also ensures that
4045 // saved_mark_word() will return top() between pauses, i.e.,
4046 // during concurrent refinement. So we don't need the
4047 // is_gc_active() check to decided which top to use when
4048 // scanning cards (see CR 7039627).
4049 increment_gc_time_stamp();
4050
4051 verify_after_gc();
4052 check_bitmaps("GC End");
4053
4054 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4055 ref_processor_stw()->verify_no_references_recorded();
4056
4057 // CM reference discovery will be re-enabled if necessary.
4058 }
4059
4060 // We should do this after we potentially expand the heap so
4061 // that all the COMMIT events are generated before the end GC
4062 // event, and after we retire the GC alloc regions so that all
4063 // RETIRE events are generated before the end GC event.
4064 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4065
4066 #ifdef TRACESPINNING
4067 ParallelTaskTerminator::print_termination_counts();
4068 #endif
4069
4070 gc_epilogue(false);
4071 }
4072
4073 // Print the remainder of the GC log output.
4074 log_gc_footer(os::elapsedTime() - pause_start_sec);
4075
4076 // It is not yet to safe to tell the concurrent mark to
4077 // start as we have some optional output below. We don't want the
4078 // output from the concurrent mark thread interfering with this
4079 // logging output either.
4080
4081 _hrm.verify_optional();
4082 verify_region_sets_optional();
4083
4084 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4085 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4086
4087 print_heap_after_gc();
4088 trace_heap_after_gc(_gc_tracer_stw);
4089
4090 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4091 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4092 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4093 // before any GC notifications are raised.
4094 g1mm()->update_sizes();
4095
4096 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4097 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4098 _gc_timer_stw->register_gc_end();
4099 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4100 }
4101 // It should now be safe to tell the concurrent mark thread to start
4102 // without its logging output interfering with the logging output
4103 // that came from the pause.
4104
4105 if (should_start_conc_mark) {
4106 // CAUTION: after the doConcurrentMark() call below,
4107 // the concurrent marking thread(s) could be running
4108 // concurrently with us. Make sure that anything after
4109 // this point does not assume that we are the only GC thread
4110 // running. Note: of course, the actual marking work will
4111 // not start until the safepoint itself is released in
4112 // SuspendibleThreadSet::desynchronize().
4113 doConcurrentMark();
4114 }
4115
4116 return true;
4117 }
4118
4119 void G1CollectedHeap::remove_self_forwarding_pointers() {
4120 double remove_self_forwards_start = os::elapsedTime();
4121
4122 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4123 workers()->run_task(&rsfp_task);
4124
4125 // Now restore saved marks, if any.
4126 for (uint i = 0; i < ParallelGCThreads; i++) {
4127 OopAndMarkOopStack& cur = _preserved_objs[i];
4128 while (!cur.is_empty()) {
4129 OopAndMarkOop elem = cur.pop();
4130 elem.set_mark();
4131 }
4132 cur.clear(true);
4133 }
4134
4135 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4136 }
4137
4138 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4139 if (!_evacuation_failed) {
4140 _evacuation_failed = true;
4141 }
4142
4143 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4144
4145 // We want to call the "for_promotion_failure" version only in the
4146 // case of a promotion failure.
4147 if (m->must_be_preserved_for_promotion_failure(obj)) {
4148 OopAndMarkOop elem(obj, m);
4149 _preserved_objs[worker_id].push(elem);
4150 }
4151 }
4152
4153 class G1ParEvacuateFollowersClosure : public VoidClosure {
4154 private:
4155 double _start_term;
4156 double _term_time;
4157 size_t _term_attempts;
4158
4159 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
4160 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
4161 protected:
4162 G1CollectedHeap* _g1h;
4163 G1ParScanThreadState* _par_scan_state;
4164 RefToScanQueueSet* _queues;
4165 ParallelTaskTerminator* _terminator;
4166
4167 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4168 RefToScanQueueSet* queues() { return _queues; }
4169 ParallelTaskTerminator* terminator() { return _terminator; }
4170
4171 public:
4172 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4173 G1ParScanThreadState* par_scan_state,
4174 RefToScanQueueSet* queues,
4175 ParallelTaskTerminator* terminator)
4176 : _g1h(g1h), _par_scan_state(par_scan_state),
4177 _queues(queues), _terminator(terminator),
4178 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
4179
4180 void do_void();
4181
4182 double term_time() const { return _term_time; }
4183 size_t term_attempts() const { return _term_attempts; }
4184
4185 private:
4186 inline bool offer_termination();
4187 };
4188
4189 bool G1ParEvacuateFollowersClosure::offer_termination() {
4190 G1ParScanThreadState* const pss = par_scan_state();
4191 start_term_time();
4192 const bool res = terminator()->offer_termination();
4193 end_term_time();
4194 return res;
4195 }
4196
4197 void G1ParEvacuateFollowersClosure::do_void() {
4198 G1ParScanThreadState* const pss = par_scan_state();
4199 pss->trim_queue();
4200 do {
4201 pss->steal_and_trim_queue(queues());
4202 } while (!offer_termination());
4203 }
4204
4205 class G1ParTask : public AbstractGangTask {
4206 protected:
4207 G1CollectedHeap* _g1h;
4208 G1ParScanThreadStateSet* _pss;
4209 RefToScanQueueSet* _queues;
4210 G1RootProcessor* _root_processor;
4211 ParallelTaskTerminator _terminator;
4212 uint _n_workers;
4213
4214 public:
4215 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4216 : AbstractGangTask("G1 collection"),
4217 _g1h(g1h),
4218 _pss(per_thread_states),
4219 _queues(task_queues),
4220 _root_processor(root_processor),
4221 _terminator(n_workers, _queues),
4222 _n_workers(n_workers)
4223 {}
4224
4225 void work(uint worker_id) {
4226 if (worker_id >= _n_workers) return; // no work needed this round
4227
4228 double start_sec = os::elapsedTime();
4229 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
4230
4231 {
4232 ResourceMark rm;
4233 HandleMark hm;
4234
4235 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4236
4237 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4238 pss->set_ref_processor(rp);
4239
4240 double start_strong_roots_sec = os::elapsedTime();
4241
4242 _root_processor->evacuate_roots(pss->closures(), worker_id);
4243
4244 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
4245
4246 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
4247 // treating the nmethods visited to act as roots for concurrent marking.
4248 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
4249 // objects copied by the current evacuation.
4250 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
4251 pss->closures()->weak_codeblobs(),
4252 worker_id);
4253
4254 _pss->add_cards_scanned(worker_id, cards_scanned);
4255
4256 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
4257
4258 double term_sec = 0.0;
4259 size_t evac_term_attempts = 0;
4260 {
4261 double start = os::elapsedTime();
4262 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
4263 evac.do_void();
4264
4265 evac_term_attempts = evac.term_attempts();
4266 term_sec = evac.term_time();
4267 double elapsed_sec = os::elapsedTime() - start;
4268 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4269 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4270 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
4271 }
4272
4273 assert(pss->queue_is_empty(), "should be empty");
4274
4275 if (PrintTerminationStats) {
4276 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4277 size_t lab_waste;
4278 size_t lab_undo_waste;
4279 pss->waste(lab_waste, lab_undo_waste);
4280 _g1h->print_termination_stats(gclog_or_tty,
4281 worker_id,
4282 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
4283 strong_roots_sec * 1000.0, /* strong roots time */
4284 term_sec * 1000.0, /* evac term time */
4285 evac_term_attempts, /* evac term attempts */
4286 lab_waste, /* alloc buffer waste */
4287 lab_undo_waste /* undo waste */
4288 );
4289 }
4290
4291 // Close the inner scope so that the ResourceMark and HandleMark
4292 // destructors are executed here and are included as part of the
4293 // "GC Worker Time".
4294 }
4295 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4296 }
4297 };
4298
4299 void G1CollectedHeap::print_termination_stats_hdr(outputStream* const st) {
4300 st->print_raw_cr("GC Termination Stats");
4301 st->print_raw_cr(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
4302 st->print_raw_cr("thr ms ms % ms % attempts total alloc undo");
4303 st->print_raw_cr("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
4304 }
4305
4306 void G1CollectedHeap::print_termination_stats(outputStream* const st,
4307 uint worker_id,
4308 double elapsed_ms,
4309 double strong_roots_ms,
4310 double term_ms,
4311 size_t term_attempts,
4312 size_t alloc_buffer_waste,
4313 size_t undo_waste) const {
4314 st->print_cr("%3d %9.2f %9.2f %6.2f "
4315 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4316 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4317 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
4318 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
4319 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
4320 alloc_buffer_waste * HeapWordSize / K,
4321 undo_waste * HeapWordSize / K);
4322 }
4323
4324 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4325 private:
4326 BoolObjectClosure* _is_alive;
4327 int _initial_string_table_size;
4328 int _initial_symbol_table_size;
4329
4330 bool _process_strings;
4331 int _strings_processed;
4332 int _strings_removed;
4333
4334 bool _process_symbols;
4335 int _symbols_processed;
4336 int _symbols_removed;
4337
4338 public:
4339 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4340 AbstractGangTask("String/Symbol Unlinking"),
4341 _is_alive(is_alive),
4342 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4343 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4344
4345 _initial_string_table_size = StringTable::the_table()->table_size();
4346 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4347 if (process_strings) {
4348 StringTable::clear_parallel_claimed_index();
4349 }
4350 if (process_symbols) {
4351 SymbolTable::clear_parallel_claimed_index();
4352 }
4353 }
4354
4355 ~G1StringSymbolTableUnlinkTask() {
4356 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4357 "claim value %d after unlink less than initial string table size %d",
4358 StringTable::parallel_claimed_index(), _initial_string_table_size);
4359 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4360 "claim value %d after unlink less than initial symbol table size %d",
4361 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
4362
4363 if (G1TraceStringSymbolTableScrubbing) {
4364 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4365 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4366 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4367 strings_processed(), strings_removed(),
4368 symbols_processed(), symbols_removed());
4369 }
4370 }
4371
4372 void work(uint worker_id) {
4373 int strings_processed = 0;
4374 int strings_removed = 0;
4375 int symbols_processed = 0;
4376 int symbols_removed = 0;
4377 if (_process_strings) {
4378 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4379 Atomic::add(strings_processed, &_strings_processed);
4380 Atomic::add(strings_removed, &_strings_removed);
4381 }
4382 if (_process_symbols) {
4383 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4384 Atomic::add(symbols_processed, &_symbols_processed);
4385 Atomic::add(symbols_removed, &_symbols_removed);
4386 }
4387 }
4388
4389 size_t strings_processed() const { return (size_t)_strings_processed; }
4390 size_t strings_removed() const { return (size_t)_strings_removed; }
4391
4392 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4393 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4394 };
4395
4396 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4397 private:
4398 static Monitor* _lock;
4399
4400 BoolObjectClosure* const _is_alive;
4401 const bool _unloading_occurred;
4402 const uint _num_workers;
4403
4404 // Variables used to claim nmethods.
4405 nmethod* _first_nmethod;
4406 volatile nmethod* _claimed_nmethod;
4407
4408 // The list of nmethods that need to be processed by the second pass.
4409 volatile nmethod* _postponed_list;
4410 volatile uint _num_entered_barrier;
4411
4412 public:
4413 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4414 _is_alive(is_alive),
4415 _unloading_occurred(unloading_occurred),
4416 _num_workers(num_workers),
4417 _first_nmethod(NULL),
4418 _claimed_nmethod(NULL),
4419 _postponed_list(NULL),
4420 _num_entered_barrier(0)
4421 {
4422 nmethod::increase_unloading_clock();
4423 // Get first alive nmethod
4424 NMethodIterator iter = NMethodIterator();
4425 if(iter.next_alive()) {
4426 _first_nmethod = iter.method();
4427 }
4428 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4429 }
4430
4431 ~G1CodeCacheUnloadingTask() {
4432 CodeCache::verify_clean_inline_caches();
4433
4434 CodeCache::set_needs_cache_clean(false);
4435 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4436
4437 CodeCache::verify_icholder_relocations();
4438 }
4439
4440 private:
4441 void add_to_postponed_list(nmethod* nm) {
4442 nmethod* old;
4443 do {
4444 old = (nmethod*)_postponed_list;
4445 nm->set_unloading_next(old);
4446 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4447 }
4448
4449 void clean_nmethod(nmethod* nm) {
4450 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4451
4452 if (postponed) {
4453 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4454 add_to_postponed_list(nm);
4455 }
4456
4457 // Mark that this thread has been cleaned/unloaded.
4458 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4459 nm->set_unloading_clock(nmethod::global_unloading_clock());
4460 }
4461
4462 void clean_nmethod_postponed(nmethod* nm) {
4463 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4464 }
4465
4466 static const int MaxClaimNmethods = 16;
4467
4468 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4469 nmethod* first;
4470 NMethodIterator last;
4471
4472 do {
4473 *num_claimed_nmethods = 0;
4474
4475 first = (nmethod*)_claimed_nmethod;
4476 last = NMethodIterator(first);
4477
4478 if (first != NULL) {
4479
4480 for (int i = 0; i < MaxClaimNmethods; i++) {
4481 if (!last.next_alive()) {
4482 break;
4483 }
4484 claimed_nmethods[i] = last.method();
4485 (*num_claimed_nmethods)++;
4486 }
4487 }
4488
4489 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4490 }
4491
4492 nmethod* claim_postponed_nmethod() {
4493 nmethod* claim;
4494 nmethod* next;
4495
4496 do {
4497 claim = (nmethod*)_postponed_list;
4498 if (claim == NULL) {
4499 return NULL;
4500 }
4501
4502 next = claim->unloading_next();
4503
4504 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4505
4506 return claim;
4507 }
4508
4509 public:
4510 // Mark that we're done with the first pass of nmethod cleaning.
4511 void barrier_mark(uint worker_id) {
4512 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4513 _num_entered_barrier++;
4514 if (_num_entered_barrier == _num_workers) {
4515 ml.notify_all();
4516 }
4517 }
4518
4519 // See if we have to wait for the other workers to
4520 // finish their first-pass nmethod cleaning work.
4521 void barrier_wait(uint worker_id) {
4522 if (_num_entered_barrier < _num_workers) {
4523 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4524 while (_num_entered_barrier < _num_workers) {
4525 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4526 }
4527 }
4528 }
4529
4530 // Cleaning and unloading of nmethods. Some work has to be postponed
4531 // to the second pass, when we know which nmethods survive.
4532 void work_first_pass(uint worker_id) {
4533 // The first nmethods is claimed by the first worker.
4534 if (worker_id == 0 && _first_nmethod != NULL) {
4535 clean_nmethod(_first_nmethod);
4536 _first_nmethod = NULL;
4537 }
4538
4539 int num_claimed_nmethods;
4540 nmethod* claimed_nmethods[MaxClaimNmethods];
4541
4542 while (true) {
4543 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4544
4545 if (num_claimed_nmethods == 0) {
4546 break;
4547 }
4548
4549 for (int i = 0; i < num_claimed_nmethods; i++) {
4550 clean_nmethod(claimed_nmethods[i]);
4551 }
4552 }
4553 }
4554
4555 void work_second_pass(uint worker_id) {
4556 nmethod* nm;
4557 // Take care of postponed nmethods.
4558 while ((nm = claim_postponed_nmethod()) != NULL) {
4559 clean_nmethod_postponed(nm);
4560 }
4561 }
4562 };
4563
4564 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4565
4566 class G1KlassCleaningTask : public StackObj {
4567 BoolObjectClosure* _is_alive;
4568 volatile jint _clean_klass_tree_claimed;
4569 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4570
4571 public:
4572 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4573 _is_alive(is_alive),
4574 _clean_klass_tree_claimed(0),
4575 _klass_iterator() {
4576 }
4577
4578 private:
4579 bool claim_clean_klass_tree_task() {
4580 if (_clean_klass_tree_claimed) {
4581 return false;
4582 }
4583
4584 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4585 }
4586
4587 InstanceKlass* claim_next_klass() {
4588 Klass* klass;
4589 do {
4590 klass =_klass_iterator.next_klass();
4591 } while (klass != NULL && !klass->is_instance_klass());
4592
4593 // this can be null so don't call InstanceKlass::cast
4594 return static_cast<InstanceKlass*>(klass);
4595 }
4596
4597 public:
4598
4599 void clean_klass(InstanceKlass* ik) {
4600 ik->clean_weak_instanceklass_links(_is_alive);
4601 }
4602
4603 void work() {
4604 ResourceMark rm;
4605
4606 // One worker will clean the subklass/sibling klass tree.
4607 if (claim_clean_klass_tree_task()) {
4608 Klass::clean_subklass_tree(_is_alive);
4609 }
4610
4611 // All workers will help cleaning the classes,
4612 InstanceKlass* klass;
4613 while ((klass = claim_next_klass()) != NULL) {
4614 clean_klass(klass);
4615 }
4616 }
4617 };
4618
4619 // To minimize the remark pause times, the tasks below are done in parallel.
4620 class G1ParallelCleaningTask : public AbstractGangTask {
4621 private:
4622 G1StringSymbolTableUnlinkTask _string_symbol_task;
4623 G1CodeCacheUnloadingTask _code_cache_task;
4624 G1KlassCleaningTask _klass_cleaning_task;
4625
4626 public:
4627 // The constructor is run in the VMThread.
4628 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4629 AbstractGangTask("Parallel Cleaning"),
4630 _string_symbol_task(is_alive, process_strings, process_symbols),
4631 _code_cache_task(num_workers, is_alive, unloading_occurred),
4632 _klass_cleaning_task(is_alive) {
4633 }
4634
4635 // The parallel work done by all worker threads.
4636 void work(uint worker_id) {
4637 // Do first pass of code cache cleaning.
4638 _code_cache_task.work_first_pass(worker_id);
4639
4640 // Let the threads mark that the first pass is done.
4641 _code_cache_task.barrier_mark(worker_id);
4642
4643 // Clean the Strings and Symbols.
4644 _string_symbol_task.work(worker_id);
4645
4646 // Wait for all workers to finish the first code cache cleaning pass.
4647 _code_cache_task.barrier_wait(worker_id);
4648
4649 // Do the second code cache cleaning work, which realize on
4650 // the liveness information gathered during the first pass.
4651 _code_cache_task.work_second_pass(worker_id);
4652
4653 // Clean all klasses that were not unloaded.
4654 _klass_cleaning_task.work();
4655 }
4656 };
4657
4658
4659 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4660 bool process_strings,
4661 bool process_symbols,
4662 bool class_unloading_occurred) {
4663 uint n_workers = workers()->active_workers();
4664
4665 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4666 n_workers, class_unloading_occurred);
4667 workers()->run_task(&g1_unlink_task);
4668 }
4669
4670 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4671 bool process_strings, bool process_symbols) {
4672 {
4673 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4674 workers()->run_task(&g1_unlink_task);
4675 }
4676
4677 if (G1StringDedup::is_enabled()) {
4678 G1StringDedup::unlink(is_alive);
4679 }
4680 }
4681
4682 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4683 private:
4684 DirtyCardQueueSet* _queue;
4685 public:
4686 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4687
4688 virtual void work(uint worker_id) {
4689 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4690 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4691
4692 RedirtyLoggedCardTableEntryClosure cl;
4693 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4694
4695 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4696 }
4697 };
4698
4699 void G1CollectedHeap::redirty_logged_cards() {
4700 double redirty_logged_cards_start = os::elapsedTime();
4701
4702 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4703 dirty_card_queue_set().reset_for_par_iteration();
4704 workers()->run_task(&redirty_task);
4705
4706 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4707 dcq.merge_bufferlists(&dirty_card_queue_set());
4708 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4709
4710 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4711 }
4712
4713 // Weak Reference Processing support
4714
4715 // An always "is_alive" closure that is used to preserve referents.
4716 // If the object is non-null then it's alive. Used in the preservation
4717 // of referent objects that are pointed to by reference objects
4718 // discovered by the CM ref processor.
4719 class G1AlwaysAliveClosure: public BoolObjectClosure {
4720 G1CollectedHeap* _g1;
4721 public:
4722 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4723 bool do_object_b(oop p) {
4724 if (p != NULL) {
4725 return true;
4726 }
4727 return false;
4728 }
4729 };
4730
4731 bool G1STWIsAliveClosure::do_object_b(oop p) {
4732 // An object is reachable if it is outside the collection set,
4733 // or is inside and copied.
4734 return !_g1->is_in_cset(p) || p->is_forwarded();
4735 }
4736
4737 // Non Copying Keep Alive closure
4738 class G1KeepAliveClosure: public OopClosure {
4739 G1CollectedHeap* _g1;
4740 public:
4741 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4742 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4743 void do_oop(oop* p) {
4744 oop obj = *p;
4745 assert(obj != NULL, "the caller should have filtered out NULL values");
4746
4747 const InCSetState cset_state = _g1->in_cset_state(obj);
4748 if (!cset_state.is_in_cset_or_humongous()) {
4749 return;
4750 }
4751 if (cset_state.is_in_cset()) {
4752 assert( obj->is_forwarded(), "invariant" );
4753 *p = obj->forwardee();
4754 } else {
4755 assert(!obj->is_forwarded(), "invariant" );
4756 assert(cset_state.is_humongous(),
4757 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4758 _g1->set_humongous_is_live(obj);
4759 }
4760 }
4761 };
4762
4763 // Copying Keep Alive closure - can be called from both
4764 // serial and parallel code as long as different worker
4765 // threads utilize different G1ParScanThreadState instances
4766 // and different queues.
4767
4768 class G1CopyingKeepAliveClosure: public OopClosure {
4769 G1CollectedHeap* _g1h;
4770 OopClosure* _copy_non_heap_obj_cl;
4771 G1ParScanThreadState* _par_scan_state;
4772
4773 public:
4774 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4775 OopClosure* non_heap_obj_cl,
4776 G1ParScanThreadState* pss):
4777 _g1h(g1h),
4778 _copy_non_heap_obj_cl(non_heap_obj_cl),
4779 _par_scan_state(pss)
4780 {}
4781
4782 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4783 virtual void do_oop( oop* p) { do_oop_work(p); }
4784
4785 template <class T> void do_oop_work(T* p) {
4786 oop obj = oopDesc::load_decode_heap_oop(p);
4787
4788 if (_g1h->is_in_cset_or_humongous(obj)) {
4789 // If the referent object has been forwarded (either copied
4790 // to a new location or to itself in the event of an
4791 // evacuation failure) then we need to update the reference
4792 // field and, if both reference and referent are in the G1
4793 // heap, update the RSet for the referent.
4794 //
4795 // If the referent has not been forwarded then we have to keep
4796 // it alive by policy. Therefore we have copy the referent.
4797 //
4798 // If the reference field is in the G1 heap then we can push
4799 // on the PSS queue. When the queue is drained (after each
4800 // phase of reference processing) the object and it's followers
4801 // will be copied, the reference field set to point to the
4802 // new location, and the RSet updated. Otherwise we need to
4803 // use the the non-heap or metadata closures directly to copy
4804 // the referent object and update the pointer, while avoiding
4805 // updating the RSet.
4806
4807 if (_g1h->is_in_g1_reserved(p)) {
4808 _par_scan_state->push_on_queue(p);
4809 } else {
4810 assert(!Metaspace::contains((const void*)p),
4811 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4812 _copy_non_heap_obj_cl->do_oop(p);
4813 }
4814 }
4815 }
4816 };
4817
4818 // Serial drain queue closure. Called as the 'complete_gc'
4819 // closure for each discovered list in some of the
4820 // reference processing phases.
4821
4822 class G1STWDrainQueueClosure: public VoidClosure {
4823 protected:
4824 G1CollectedHeap* _g1h;
4825 G1ParScanThreadState* _par_scan_state;
4826
4827 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4828
4829 public:
4830 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4831 _g1h(g1h),
4832 _par_scan_state(pss)
4833 { }
4834
4835 void do_void() {
4836 G1ParScanThreadState* const pss = par_scan_state();
4837 pss->trim_queue();
4838 }
4839 };
4840
4841 // Parallel Reference Processing closures
4842
4843 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4844 // processing during G1 evacuation pauses.
4845
4846 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4847 private:
4848 G1CollectedHeap* _g1h;
4849 G1ParScanThreadStateSet* _pss;
4850 RefToScanQueueSet* _queues;
4851 WorkGang* _workers;
4852 uint _active_workers;
4853
4854 public:
4855 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4856 G1ParScanThreadStateSet* per_thread_states,
4857 WorkGang* workers,
4858 RefToScanQueueSet *task_queues,
4859 uint n_workers) :
4860 _g1h(g1h),
4861 _pss(per_thread_states),
4862 _queues(task_queues),
4863 _workers(workers),
4864 _active_workers(n_workers)
4865 {
4866 assert(n_workers > 0, "shouldn't call this otherwise");
4867 }
4868
4869 // Executes the given task using concurrent marking worker threads.
4870 virtual void execute(ProcessTask& task);
4871 virtual void execute(EnqueueTask& task);
4872 };
4873
4874 // Gang task for possibly parallel reference processing
4875
4876 class G1STWRefProcTaskProxy: public AbstractGangTask {
4877 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4878 ProcessTask& _proc_task;
4879 G1CollectedHeap* _g1h;
4880 G1ParScanThreadStateSet* _pss;
4881 RefToScanQueueSet* _task_queues;
4882 ParallelTaskTerminator* _terminator;
4883
4884 public:
4885 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4886 G1CollectedHeap* g1h,
4887 G1ParScanThreadStateSet* per_thread_states,
4888 RefToScanQueueSet *task_queues,
4889 ParallelTaskTerminator* terminator) :
4890 AbstractGangTask("Process reference objects in parallel"),
4891 _proc_task(proc_task),
4892 _g1h(g1h),
4893 _pss(per_thread_states),
4894 _task_queues(task_queues),
4895 _terminator(terminator)
4896 {}
4897
4898 virtual void work(uint worker_id) {
4899 // The reference processing task executed by a single worker.
4900 ResourceMark rm;
4901 HandleMark hm;
4902
4903 G1STWIsAliveClosure is_alive(_g1h);
4904
4905 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4906 pss->set_ref_processor(NULL);
4907
4908 // Keep alive closure.
4909 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4910
4911 // Complete GC closure
4912 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4913
4914 // Call the reference processing task's work routine.
4915 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4916
4917 // Note we cannot assert that the refs array is empty here as not all
4918 // of the processing tasks (specifically phase2 - pp2_work) execute
4919 // the complete_gc closure (which ordinarily would drain the queue) so
4920 // the queue may not be empty.
4921 }
4922 };
4923
4924 // Driver routine for parallel reference processing.
4925 // Creates an instance of the ref processing gang
4926 // task and has the worker threads execute it.
4927 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4928 assert(_workers != NULL, "Need parallel worker threads.");
4929
4930 ParallelTaskTerminator terminator(_active_workers, _queues);
4931 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4932
4933 _workers->run_task(&proc_task_proxy);
4934 }
4935
4936 // Gang task for parallel reference enqueueing.
4937
4938 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4939 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4940 EnqueueTask& _enq_task;
4941
4942 public:
4943 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4944 AbstractGangTask("Enqueue reference objects in parallel"),
4945 _enq_task(enq_task)
4946 { }
4947
4948 virtual void work(uint worker_id) {
4949 _enq_task.work(worker_id);
4950 }
4951 };
4952
4953 // Driver routine for parallel reference enqueueing.
4954 // Creates an instance of the ref enqueueing gang
4955 // task and has the worker threads execute it.
4956
4957 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4958 assert(_workers != NULL, "Need parallel worker threads.");
4959
4960 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4961
4962 _workers->run_task(&enq_task_proxy);
4963 }
4964
4965 // End of weak reference support closures
4966
4967 // Abstract task used to preserve (i.e. copy) any referent objects
4968 // that are in the collection set and are pointed to by reference
4969 // objects discovered by the CM ref processor.
4970
4971 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4972 protected:
4973 G1CollectedHeap* _g1h;
4974 G1ParScanThreadStateSet* _pss;
4975 RefToScanQueueSet* _queues;
4976 ParallelTaskTerminator _terminator;
4977 uint _n_workers;
4978
4979 public:
4980 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4981 AbstractGangTask("ParPreserveCMReferents"),
4982 _g1h(g1h),
4983 _pss(per_thread_states),
4984 _queues(task_queues),
4985 _terminator(workers, _queues),
4986 _n_workers(workers)
4987 { }
4988
4989 void work(uint worker_id) {
4990 ResourceMark rm;
4991 HandleMark hm;
4992
4993 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4994 pss->set_ref_processor(NULL);
4995 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4996
4997 // Is alive closure
4998 G1AlwaysAliveClosure always_alive(_g1h);
4999
5000 // Copying keep alive closure. Applied to referent objects that need
5001 // to be copied.
5002 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
5003
5004 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5005
5006 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5007 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5008
5009 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5010 // So this must be true - but assert just in case someone decides to
5011 // change the worker ids.
5012 assert(worker_id < limit, "sanity");
5013 assert(!rp->discovery_is_atomic(), "check this code");
5014
5015 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5016 for (uint idx = worker_id; idx < limit; idx += stride) {
5017 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5018
5019 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5020 while (iter.has_next()) {
5021 // Since discovery is not atomic for the CM ref processor, we
5022 // can see some null referent objects.
5023 iter.load_ptrs(DEBUG_ONLY(true));
5024 oop ref = iter.obj();
5025
5026 // This will filter nulls.
5027 if (iter.is_referent_alive()) {
5028 iter.make_referent_alive();
5029 }
5030 iter.move_to_next();
5031 }
5032 }
5033
5034 // Drain the queue - which may cause stealing
5035 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
5036 drain_queue.do_void();
5037 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5038 assert(pss->queue_is_empty(), "should be");
5039 }
5040 };
5041
5042 // Weak Reference processing during an evacuation pause (part 1).
5043 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5044 double ref_proc_start = os::elapsedTime();
5045
5046 ReferenceProcessor* rp = _ref_processor_stw;
5047 assert(rp->discovery_enabled(), "should have been enabled");
5048
5049 // Any reference objects, in the collection set, that were 'discovered'
5050 // by the CM ref processor should have already been copied (either by
5051 // applying the external root copy closure to the discovered lists, or
5052 // by following an RSet entry).
5053 //
5054 // But some of the referents, that are in the collection set, that these
5055 // reference objects point to may not have been copied: the STW ref
5056 // processor would have seen that the reference object had already
5057 // been 'discovered' and would have skipped discovering the reference,
5058 // but would not have treated the reference object as a regular oop.
5059 // As a result the copy closure would not have been applied to the
5060 // referent object.
5061 //
5062 // We need to explicitly copy these referent objects - the references
5063 // will be processed at the end of remarking.
5064 //
5065 // We also need to do this copying before we process the reference
5066 // objects discovered by the STW ref processor in case one of these
5067 // referents points to another object which is also referenced by an
5068 // object discovered by the STW ref processor.
5069
5070 uint no_of_gc_workers = workers()->active_workers();
5071
5072 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5073 per_thread_states,
5074 no_of_gc_workers,
5075 _task_queues);
5076
5077 workers()->run_task(&keep_cm_referents);
5078
5079 // Closure to test whether a referent is alive.
5080 G1STWIsAliveClosure is_alive(this);
5081
5082 // Even when parallel reference processing is enabled, the processing
5083 // of JNI refs is serial and performed serially by the current thread
5084 // rather than by a worker. The following PSS will be used for processing
5085 // JNI refs.
5086
5087 // Use only a single queue for this PSS.
5088 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
5089 pss->set_ref_processor(NULL);
5090 assert(pss->queue_is_empty(), "pre-condition");
5091
5092 // Keep alive closure.
5093 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
5094
5095 // Serial Complete GC closure
5096 G1STWDrainQueueClosure drain_queue(this, pss);
5097
5098 // Setup the soft refs policy...
5099 rp->setup_policy(false);
5100
5101 ReferenceProcessorStats stats;
5102 if (!rp->processing_is_mt()) {
5103 // Serial reference processing...
5104 stats = rp->process_discovered_references(&is_alive,
5105 &keep_alive,
5106 &drain_queue,
5107 NULL,
5108 _gc_timer_stw);
5109 } else {
5110 // Parallel reference processing
5111 assert(rp->num_q() == no_of_gc_workers, "sanity");
5112 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5113
5114 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
5115 stats = rp->process_discovered_references(&is_alive,
5116 &keep_alive,
5117 &drain_queue,
5118 &par_task_executor,
5119 _gc_timer_stw);
5120 }
5121
5122 _gc_tracer_stw->report_gc_reference_stats(stats);
5123
5124 // We have completed copying any necessary live referent objects.
5125 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
5126
5127 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5128 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5129 }
5130
5131 // Weak Reference processing during an evacuation pause (part 2).
5132 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
5133 double ref_enq_start = os::elapsedTime();
5134
5135 ReferenceProcessor* rp = _ref_processor_stw;
5136 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5137
5138 // Now enqueue any remaining on the discovered lists on to
5139 // the pending list.
5140 if (!rp->processing_is_mt()) {
5141 // Serial reference processing...
5142 rp->enqueue_discovered_references();
5143 } else {
5144 // Parallel reference enqueueing
5145
5146 uint n_workers = workers()->active_workers();
5147
5148 assert(rp->num_q() == n_workers, "sanity");
5149 assert(n_workers <= rp->max_num_q(), "sanity");
5150
5151 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
5152 rp->enqueue_discovered_references(&par_task_executor);
5153 }
5154
5155 rp->verify_no_references_recorded();
5156 assert(!rp->discovery_enabled(), "should have been disabled");
5157
5158 // FIXME
5159 // CM's reference processing also cleans up the string and symbol tables.
5160 // Should we do that here also? We could, but it is a serial operation
5161 // and could significantly increase the pause time.
5162
5163 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5164 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5165 }
5166
5167 void G1CollectedHeap::pre_evacuate_collection_set() {
5168 _expand_heap_after_alloc_failure = true;
5169 _evacuation_failed = false;
5170
5171 // Disable the hot card cache.
5172 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5173 hot_card_cache->reset_hot_cache_claimed_index();
5174 hot_card_cache->set_use_cache(false);
5175
5176 }
5177
5178 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5179 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5180
5181 // Should G1EvacuationFailureALot be in effect for this GC?
5182 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5183
5184 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5185 double start_par_time_sec = os::elapsedTime();
5186 double end_par_time_sec;
5187
5188 {
5189 const uint n_workers = workers()->active_workers();
5190 G1RootProcessor root_processor(this, n_workers);
5191 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
5192 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5193 if (collector_state()->during_initial_mark_pause()) {
5194 ClassLoaderDataGraph::clear_claimed_marks();
5195 }
5196
5197 // The individual threads will set their evac-failure closures.
5198 if (PrintTerminationStats) {
5199 print_termination_stats_hdr(gclog_or_tty);
5200 }
5201
5202 workers()->run_task(&g1_par_task);
5203 end_par_time_sec = os::elapsedTime();
5204
5205 // Closing the inner scope will execute the destructor
5206 // for the G1RootProcessor object. We record the current
5207 // elapsed time before closing the scope so that time
5208 // taken for the destructor is NOT included in the
5209 // reported parallel time.
5210 }
5211
5212 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5213
5214 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5215 phase_times->record_par_time(par_time_ms);
5216
5217 double code_root_fixup_time_ms =
5218 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5219 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5220
5221 // Process any discovered reference objects - we have
5222 // to do this _before_ we retire the GC alloc regions
5223 // as we may have to copy some 'reachable' referent
5224 // objects (and their reachable sub-graphs) that were
5225 // not copied during the pause.
5226 process_discovered_references(per_thread_states);
5227
5228 if (G1StringDedup::is_enabled()) {
5229 double fixup_start = os::elapsedTime();
5230
5231 G1STWIsAliveClosure is_alive(this);
5232 G1KeepAliveClosure keep_alive(this);
5233 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5234
5235 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5236 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5237 }
5238
5239 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5240
5241 if (evacuation_failed()) {
5242 remove_self_forwarding_pointers();
5243
5244 // Reset the G1EvacuationFailureALot counters and flags
5245 // Note: the values are reset only when an actual
5246 // evacuation failure occurs.
5247 NOT_PRODUCT(reset_evacuation_should_fail();)
5248 }
5249
5250 // Enqueue any remaining references remaining on the STW
5251 // reference processor's discovered lists. We need to do
5252 // this after the card table is cleaned (and verified) as
5253 // the act of enqueueing entries on to the pending list
5254 // will log these updates (and dirty their associated
5255 // cards). We need these updates logged to update any
5256 // RSets.
5257 enqueue_discovered_references(per_thread_states);
5258 }
5259
5260 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
5261 _allocator->release_gc_alloc_regions(evacuation_info);
5262
5263 per_thread_states->flush();
5264
5265 record_obj_copy_mem_stats();
5266
5267 // Reset and re-enable the hot card cache.
5268 // Note the counts for the cards in the regions in the
5269 // collection set are reset when the collection set is freed.
5270 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5271 hot_card_cache->reset_hot_cache();
5272 hot_card_cache->set_use_cache(true);
5273
5274 purge_code_root_memory();
5275
5276 redirty_logged_cards();
5277 #if defined(COMPILER2) || INCLUDE_JVMCI
5278 DerivedPointerTable::update_pointers();
5279 #endif
5280 }
5281
5282 void G1CollectedHeap::record_obj_copy_mem_stats() {
5283 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
5284 create_g1_evac_summary(&_old_evac_stats));
5285 }
5286
5287 void G1CollectedHeap::free_region(HeapRegion* hr,
5288 FreeRegionList* free_list,
5289 bool par,
5290 bool locked) {
5291 assert(!hr->is_free(), "the region should not be free");
5292 assert(!hr->is_empty(), "the region should not be empty");
5293 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5294 assert(free_list != NULL, "pre-condition");
5295
5296 if (G1VerifyBitmaps) {
5297 MemRegion mr(hr->bottom(), hr->end());
5298 concurrent_mark()->clearRangePrevBitmap(mr);
5299 }
5300
5301 // Clear the card counts for this region.
5302 // Note: we only need to do this if the region is not young
5303 // (since we don't refine cards in young regions).
5304 if (!hr->is_young()) {
5305 _cg1r->hot_card_cache()->reset_card_counts(hr);
5306 }
5307 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5308 free_list->add_ordered(hr);
5309 }
5310
5311 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5312 FreeRegionList* free_list,
5313 bool par) {
5314 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5315 assert(free_list != NULL, "pre-condition");
5316
5317 size_t hr_capacity = hr->capacity();
5318 // We need to read this before we make the region non-humongous,
5319 // otherwise the information will be gone.
5320 uint last_index = hr->last_hc_index();
5321 hr->clear_humongous();
5322 free_region(hr, free_list, par);
5323
5324 uint i = hr->hrm_index() + 1;
5325 while (i < last_index) {
5326 HeapRegion* curr_hr = region_at(i);
5327 assert(curr_hr->is_continues_humongous(), "invariant");
5328 curr_hr->clear_humongous();
5329 free_region(curr_hr, free_list, par);
5330 i += 1;
5331 }
5332 }
5333
5334 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5335 const HeapRegionSetCount& humongous_regions_removed) {
5336 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5337 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5338 _old_set.bulk_remove(old_regions_removed);
5339 _humongous_set.bulk_remove(humongous_regions_removed);
5340 }
5341
5342 }
5343
5344 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5345 assert(list != NULL, "list can't be null");
5346 if (!list->is_empty()) {
5347 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5348 _hrm.insert_list_into_free_list(list);
5349 }
5350 }
5351
5352 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5353 decrease_used(bytes);
5354 }
5355
5356 class G1ParCleanupCTTask : public AbstractGangTask {
5357 G1SATBCardTableModRefBS* _ct_bs;
5358 G1CollectedHeap* _g1h;
5359 HeapRegion* volatile _su_head;
5360 public:
5361 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5362 G1CollectedHeap* g1h) :
5363 AbstractGangTask("G1 Par Cleanup CT Task"),
5364 _ct_bs(ct_bs), _g1h(g1h) { }
5365
5366 void work(uint worker_id) {
5367 HeapRegion* r;
5368 while (r = _g1h->pop_dirty_cards_region()) {
5369 clear_cards(r);
5370 }
5371 }
5372
5373 void clear_cards(HeapRegion* r) {
5374 // Cards of the survivors should have already been dirtied.
5375 if (!r->is_survivor()) {
5376 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5377 }
5378 }
5379 };
5380
5381 #ifndef PRODUCT
5382 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5383 G1CollectedHeap* _g1h;
5384 G1SATBCardTableModRefBS* _ct_bs;
5385 public:
5386 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5387 : _g1h(g1h), _ct_bs(ct_bs) { }
5388 virtual bool doHeapRegion(HeapRegion* r) {
5389 if (r->is_survivor()) {
5390 _g1h->verify_dirty_region(r);
5391 } else {
5392 _g1h->verify_not_dirty_region(r);
5393 }
5394 return false;
5395 }
5396 };
5397
5398 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5399 // All of the region should be clean.
5400 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5401 MemRegion mr(hr->bottom(), hr->end());
5402 ct_bs->verify_not_dirty_region(mr);
5403 }
5404
5405 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5406 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5407 // dirty allocated blocks as they allocate them. The thread that
5408 // retires each region and replaces it with a new one will do a
5409 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5410 // not dirty that area (one less thing to have to do while holding
5411 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5412 // is dirty.
5413 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5414 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5415 if (hr->is_young()) {
5416 ct_bs->verify_g1_young_region(mr);
5417 } else {
5418 ct_bs->verify_dirty_region(mr);
5419 }
5420 }
5421
5422 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5423 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5424 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5425 verify_dirty_region(hr);
5426 }
5427 }
5428
5429 void G1CollectedHeap::verify_dirty_young_regions() {
5430 verify_dirty_young_list(_young_list->first_region());
5431 }
5432
5433 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5434 HeapWord* tams, HeapWord* end) {
5435 guarantee(tams <= end,
5436 "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
5437 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5438 if (result < end) {
5439 gclog_or_tty->cr();
5440 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5441 bitmap_name, p2i(result));
5442 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5443 bitmap_name, p2i(tams), p2i(end));
5444 return false;
5445 }
5446 return true;
5447 }
5448
5449 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5450 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5451 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5452
5453 HeapWord* bottom = hr->bottom();
5454 HeapWord* ptams = hr->prev_top_at_mark_start();
5455 HeapWord* ntams = hr->next_top_at_mark_start();
5456 HeapWord* end = hr->end();
5457
5458 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5459
5460 bool res_n = true;
5461 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5462 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5463 // if we happen to be in that state.
5464 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5465 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5466 }
5467 if (!res_p || !res_n) {
5468 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5469 HR_FORMAT_PARAMS(hr));
5470 gclog_or_tty->print_cr("#### Caller: %s", caller);
5471 return false;
5472 }
5473 return true;
5474 }
5475
5476 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5477 if (!G1VerifyBitmaps) return;
5478
5479 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5480 }
5481
5482 class G1VerifyBitmapClosure : public HeapRegionClosure {
5483 private:
5484 const char* _caller;
5485 G1CollectedHeap* _g1h;
5486 bool _failures;
5487
5488 public:
5489 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5490 _caller(caller), _g1h(g1h), _failures(false) { }
5491
5492 bool failures() { return _failures; }
5493
5494 virtual bool doHeapRegion(HeapRegion* hr) {
5495 if (hr->is_continues_humongous()) return false;
5496
5497 bool result = _g1h->verify_bitmaps(_caller, hr);
5498 if (!result) {
5499 _failures = true;
5500 }
5501 return false;
5502 }
5503 };
5504
5505 void G1CollectedHeap::check_bitmaps(const char* caller) {
5506 if (!G1VerifyBitmaps) return;
5507
5508 G1VerifyBitmapClosure cl(caller, this);
5509 heap_region_iterate(&cl);
5510 guarantee(!cl.failures(), "bitmap verification");
5511 }
5512
5513 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5514 private:
5515 bool _failures;
5516 public:
5517 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5518
5519 virtual bool doHeapRegion(HeapRegion* hr) {
5520 uint i = hr->hrm_index();
5521 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5522 if (hr->is_humongous()) {
5523 if (hr->in_collection_set()) {
5524 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5525 _failures = true;
5526 return true;
5527 }
5528 if (cset_state.is_in_cset()) {
5529 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5530 _failures = true;
5531 return true;
5532 }
5533 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5534 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5535 _failures = true;
5536 return true;
5537 }
5538 } else {
5539 if (cset_state.is_humongous()) {
5540 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5541 _failures = true;
5542 return true;
5543 }
5544 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5545 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5546 hr->in_collection_set(), cset_state.value(), i);
5547 _failures = true;
5548 return true;
5549 }
5550 if (cset_state.is_in_cset()) {
5551 if (hr->is_young() != (cset_state.is_young())) {
5552 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5553 hr->is_young(), cset_state.value(), i);
5554 _failures = true;
5555 return true;
5556 }
5557 if (hr->is_old() != (cset_state.is_old())) {
5558 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5559 hr->is_old(), cset_state.value(), i);
5560 _failures = true;
5561 return true;
5562 }
5563 }
5564 }
5565 return false;
5566 }
5567
5568 bool failures() const { return _failures; }
5569 };
5570
5571 bool G1CollectedHeap::check_cset_fast_test() {
5572 G1CheckCSetFastTableClosure cl;
5573 _hrm.iterate(&cl);
5574 return !cl.failures();
5575 }
5576 #endif // PRODUCT
5577
5578 void G1CollectedHeap::cleanUpCardTable() {
5579 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5580 double start = os::elapsedTime();
5581
5582 {
5583 // Iterate over the dirty cards region list.
5584 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5585
5586 workers()->run_task(&cleanup_task);
5587 #ifndef PRODUCT
5588 if (G1VerifyCTCleanup || VerifyAfterGC) {
5589 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5590 heap_region_iterate(&cleanup_verifier);
5591 }
5592 #endif
5593 }
5594
5595 double elapsed = os::elapsedTime() - start;
5596 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5597 }
5598
5599 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
5600 size_t pre_used = 0;
5601 FreeRegionList local_free_list("Local List for CSet Freeing");
5602
5603 double young_time_ms = 0.0;
5604 double non_young_time_ms = 0.0;
5605
5606 // Since the collection set is a superset of the the young list,
5607 // all we need to do to clear the young list is clear its
5608 // head and length, and unlink any young regions in the code below
5609 _young_list->clear();
5610
5611 G1CollectorPolicy* policy = g1_policy();
5612
5613 double start_sec = os::elapsedTime();
5614 bool non_young = true;
5615
5616 HeapRegion* cur = cs_head;
5617 int age_bound = -1;
5618 size_t rs_lengths = 0;
5619
5620 while (cur != NULL) {
5621 assert(!is_on_master_free_list(cur), "sanity");
5622 if (non_young) {
5623 if (cur->is_young()) {
5624 double end_sec = os::elapsedTime();
5625 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5626 non_young_time_ms += elapsed_ms;
5627
5628 start_sec = os::elapsedTime();
5629 non_young = false;
5630 }
5631 } else {
5632 if (!cur->is_young()) {
5633 double end_sec = os::elapsedTime();
5634 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5635 young_time_ms += elapsed_ms;
5636
5637 start_sec = os::elapsedTime();
5638 non_young = true;
5639 }
5640 }
5641
5642 rs_lengths += cur->rem_set()->occupied_locked();
5643
5644 HeapRegion* next = cur->next_in_collection_set();
5645 assert(cur->in_collection_set(), "bad CS");
5646 cur->set_next_in_collection_set(NULL);
5647 clear_in_cset(cur);
5648
5649 if (cur->is_young()) {
5650 int index = cur->young_index_in_cset();
5651 assert(index != -1, "invariant");
5652 assert((uint) index < policy->young_cset_region_length(), "invariant");
5653 size_t words_survived = surviving_young_words[index];
5654 cur->record_surv_words_in_group(words_survived);
5655
5656 // At this point the we have 'popped' cur from the collection set
5657 // (linked via next_in_collection_set()) but it is still in the
5658 // young list (linked via next_young_region()). Clear the
5659 // _next_young_region field.
5660 cur->set_next_young_region(NULL);
5661 } else {
5662 int index = cur->young_index_in_cset();
5663 assert(index == -1, "invariant");
5664 }
5665
5666 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5667 (!cur->is_young() && cur->young_index_in_cset() == -1),
5668 "invariant" );
5669
5670 if (!cur->evacuation_failed()) {
5671 MemRegion used_mr = cur->used_region();
5672
5673 // And the region is empty.
5674 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5675 pre_used += cur->used();
5676 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5677 } else {
5678 cur->uninstall_surv_rate_group();
5679 if (cur->is_young()) {
5680 cur->set_young_index_in_cset(-1);
5681 }
5682 cur->set_evacuation_failed(false);
5683 // The region is now considered to be old.
5684 cur->set_old();
5685 // Do some allocation statistics accounting. Regions that failed evacuation
5686 // are always made old, so there is no need to update anything in the young
5687 // gen statistics, but we need to update old gen statistics.
5688 size_t used_words = cur->marked_bytes() / HeapWordSize;
5689 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
5690 _old_set.add(cur);
5691 evacuation_info.increment_collectionset_used_after(cur->used());
5692 }
5693 cur = next;
5694 }
5695
5696 evacuation_info.set_regions_freed(local_free_list.length());
5697 policy->record_max_rs_lengths(rs_lengths);
5698 policy->cset_regions_freed();
5699
5700 double end_sec = os::elapsedTime();
5701 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5702
5703 if (non_young) {
5704 non_young_time_ms += elapsed_ms;
5705 } else {
5706 young_time_ms += elapsed_ms;
5707 }
5708
5709 prepend_to_freelist(&local_free_list);
5710 decrement_summary_bytes(pre_used);
5711 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5712 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5713 }
5714
5715 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5716 private:
5717 FreeRegionList* _free_region_list;
5718 HeapRegionSet* _proxy_set;
5719 HeapRegionSetCount _humongous_regions_removed;
5720 size_t _freed_bytes;
5721 public:
5722
5723 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5724 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5725 }
5726
5727 virtual bool doHeapRegion(HeapRegion* r) {
5728 if (!r->is_starts_humongous()) {
5729 return false;
5730 }
5731
5732 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5733
5734 oop obj = (oop)r->bottom();
5735 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5736
5737 // The following checks whether the humongous object is live are sufficient.
5738 // The main additional check (in addition to having a reference from the roots
5739 // or the young gen) is whether the humongous object has a remembered set entry.
5740 //
5741 // A humongous object cannot be live if there is no remembered set for it
5742 // because:
5743 // - there can be no references from within humongous starts regions referencing
5744 // the object because we never allocate other objects into them.
5745 // (I.e. there are no intra-region references that may be missed by the
5746 // remembered set)
5747 // - as soon there is a remembered set entry to the humongous starts region
5748 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5749 // until the end of a concurrent mark.
5750 //
5751 // It is not required to check whether the object has been found dead by marking
5752 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5753 // all objects allocated during that time are considered live.
5754 // SATB marking is even more conservative than the remembered set.
5755 // So if at this point in the collection there is no remembered set entry,
5756 // nobody has a reference to it.
5757 // At the start of collection we flush all refinement logs, and remembered sets
5758 // are completely up-to-date wrt to references to the humongous object.
5759 //
5760 // Other implementation considerations:
5761 // - never consider object arrays at this time because they would pose
5762 // considerable effort for cleaning up the the remembered sets. This is
5763 // required because stale remembered sets might reference locations that
5764 // are currently allocated into.
5765 uint region_idx = r->hrm_index();
5766 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5767 !r->rem_set()->is_empty()) {
5768
5769 if (G1TraceEagerReclaimHumongousObjects) {
5770 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",
5771 region_idx,
5772 (size_t)obj->size() * HeapWordSize,
5773 p2i(r->bottom()),
5774 r->region_num(),
5775 r->rem_set()->occupied(),
5776 r->rem_set()->strong_code_roots_list_length(),
5777 next_bitmap->isMarked(r->bottom()),
5778 g1h->is_humongous_reclaim_candidate(region_idx),
5779 obj->is_typeArray()
5780 );
5781 }
5782
5783 return false;
5784 }
5785
5786 guarantee(obj->is_typeArray(),
5787 "Only eagerly reclaiming type arrays is supported, but the object "
5788 PTR_FORMAT " is not.", p2i(r->bottom()));
5789
5790 if (G1TraceEagerReclaimHumongousObjects) {
5791 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",
5792 region_idx,
5793 (size_t)obj->size() * HeapWordSize,
5794 p2i(r->bottom()),
5795 r->region_num(),
5796 r->rem_set()->occupied(),
5797 r->rem_set()->strong_code_roots_list_length(),
5798 next_bitmap->isMarked(r->bottom()),
5799 g1h->is_humongous_reclaim_candidate(region_idx),
5800 obj->is_typeArray()
5801 );
5802 }
5803 // Need to clear mark bit of the humongous object if already set.
5804 if (next_bitmap->isMarked(r->bottom())) {
5805 next_bitmap->clear(r->bottom());
5806 }
5807 _freed_bytes += r->used();
5808 r->set_containing_set(NULL);
5809 _humongous_regions_removed.increment(1u, r->capacity());
5810 g1h->free_humongous_region(r, _free_region_list, false);
5811
5812 return false;
5813 }
5814
5815 HeapRegionSetCount& humongous_free_count() {
5816 return _humongous_regions_removed;
5817 }
5818
5819 size_t bytes_freed() const {
5820 return _freed_bytes;
5821 }
5822
5823 size_t humongous_reclaimed() const {
5824 return _humongous_regions_removed.length();
5825 }
5826 };
5827
5828 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5829 assert_at_safepoint(true);
5830
5831 if (!G1EagerReclaimHumongousObjects ||
5832 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5833 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5834 return;
5835 }
5836
5837 double start_time = os::elapsedTime();
5838
5839 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5840
5841 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5842 heap_region_iterate(&cl);
5843
5844 HeapRegionSetCount empty_set;
5845 remove_from_old_sets(empty_set, cl.humongous_free_count());
5846
5847 G1HRPrinter* hrp = hr_printer();
5848 if (hrp->is_active()) {
5849 FreeRegionListIterator iter(&local_cleanup_list);
5850 while (iter.more_available()) {
5851 HeapRegion* hr = iter.get_next();
5852 hrp->cleanup(hr);
5853 }
5854 }
5855
5856 prepend_to_freelist(&local_cleanup_list);
5857 decrement_summary_bytes(cl.bytes_freed());
5858
5859 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5860 cl.humongous_reclaimed());
5861 }
5862
5863 // This routine is similar to the above but does not record
5864 // any policy statistics or update free lists; we are abandoning
5865 // the current incremental collection set in preparation of a
5866 // full collection. After the full GC we will start to build up
5867 // the incremental collection set again.
5868 // This is only called when we're doing a full collection
5869 // and is immediately followed by the tearing down of the young list.
5870
5871 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5872 HeapRegion* cur = cs_head;
5873
5874 while (cur != NULL) {
5875 HeapRegion* next = cur->next_in_collection_set();
5876 assert(cur->in_collection_set(), "bad CS");
5877 cur->set_next_in_collection_set(NULL);
5878 clear_in_cset(cur);
5879 cur->set_young_index_in_cset(-1);
5880 cur = next;
5881 }
5882 }
5883
5884 void G1CollectedHeap::set_free_regions_coming() {
5885 if (G1ConcRegionFreeingVerbose) {
5886 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5887 "setting free regions coming");
5888 }
5889
5890 assert(!free_regions_coming(), "pre-condition");
5891 _free_regions_coming = true;
5892 }
5893
5894 void G1CollectedHeap::reset_free_regions_coming() {
5895 assert(free_regions_coming(), "pre-condition");
5896
5897 {
5898 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5899 _free_regions_coming = false;
5900 SecondaryFreeList_lock->notify_all();
5901 }
5902
5903 if (G1ConcRegionFreeingVerbose) {
5904 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5905 "reset free regions coming");
5906 }
5907 }
5908
5909 void G1CollectedHeap::wait_while_free_regions_coming() {
5910 // Most of the time we won't have to wait, so let's do a quick test
5911 // first before we take the lock.
5912 if (!free_regions_coming()) {
5913 return;
5914 }
5915
5916 if (G1ConcRegionFreeingVerbose) {
5917 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5918 "waiting for free regions");
5919 }
5920
5921 {
5922 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5923 while (free_regions_coming()) {
5924 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5925 }
5926 }
5927
5928 if (G1ConcRegionFreeingVerbose) {
5929 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5930 "done waiting for free regions");
5931 }
5932 }
5933
5934 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5935 return _allocator->is_retained_old_region(hr);
5936 }
5937
5938 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5939 _young_list->push_region(hr);
5940 }
5941
5942 class NoYoungRegionsClosure: public HeapRegionClosure {
5943 private:
5944 bool _success;
5945 public:
5946 NoYoungRegionsClosure() : _success(true) { }
5947 bool doHeapRegion(HeapRegion* r) {
5948 if (r->is_young()) {
5949 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5950 p2i(r->bottom()), p2i(r->end()));
5951 _success = false;
5952 }
5953 return false;
5954 }
5955 bool success() { return _success; }
5956 };
5957
5958 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5959 bool ret = _young_list->check_list_empty(check_sample);
5960
5961 if (check_heap) {
5962 NoYoungRegionsClosure closure;
5963 heap_region_iterate(&closure);
5964 ret = ret && closure.success();
5965 }
5966
5967 return ret;
5968 }
5969
5970 class TearDownRegionSetsClosure : public HeapRegionClosure {
5971 private:
5972 HeapRegionSet *_old_set;
5973
5974 public:
5975 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5976
5977 bool doHeapRegion(HeapRegion* r) {
5978 if (r->is_old()) {
5979 _old_set->remove(r);
5980 } else {
5981 // We ignore free regions, we'll empty the free list afterwards.
5982 // We ignore young regions, we'll empty the young list afterwards.
5983 // We ignore humongous regions, we're not tearing down the
5984 // humongous regions set.
5985 assert(r->is_free() || r->is_young() || r->is_humongous(),
5986 "it cannot be another type");
5987 }
5988 return false;
5989 }
5990
5991 ~TearDownRegionSetsClosure() {
5992 assert(_old_set->is_empty(), "post-condition");
5993 }
5994 };
5995
5996 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5997 assert_at_safepoint(true /* should_be_vm_thread */);
5998
5999 if (!free_list_only) {
6000 TearDownRegionSetsClosure cl(&_old_set);
6001 heap_region_iterate(&cl);
6002
6003 // Note that emptying the _young_list is postponed and instead done as
6004 // the first step when rebuilding the regions sets again. The reason for
6005 // this is that during a full GC string deduplication needs to know if
6006 // a collected region was young or old when the full GC was initiated.
6007 }
6008 _hrm.remove_all_free_regions();
6009 }
6010
6011 void G1CollectedHeap::increase_used(size_t bytes) {
6012 _summary_bytes_used += bytes;
6013 }
6014
6015 void G1CollectedHeap::decrease_used(size_t bytes) {
6016 assert(_summary_bytes_used >= bytes,
6017 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6018 _summary_bytes_used, bytes);
6019 _summary_bytes_used -= bytes;
6020 }
6021
6022 void G1CollectedHeap::set_used(size_t bytes) {
6023 _summary_bytes_used = bytes;
6024 }
6025
6026 class RebuildRegionSetsClosure : public HeapRegionClosure {
6027 private:
6028 bool _free_list_only;
6029 HeapRegionSet* _old_set;
6030 HeapRegionManager* _hrm;
6031 size_t _total_used;
6032
6033 public:
6034 RebuildRegionSetsClosure(bool free_list_only,
6035 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6036 _free_list_only(free_list_only),
6037 _old_set(old_set), _hrm(hrm), _total_used(0) {
6038 assert(_hrm->num_free_regions() == 0, "pre-condition");
6039 if (!free_list_only) {
6040 assert(_old_set->is_empty(), "pre-condition");
6041 }
6042 }
6043
6044 bool doHeapRegion(HeapRegion* r) {
6045 if (r->is_continues_humongous()) {
6046 return false;
6047 }
6048
6049 if (r->is_empty()) {
6050 // Add free regions to the free list
6051 r->set_free();
6052 r->set_allocation_context(AllocationContext::system());
6053 _hrm->insert_into_free_list(r);
6054 } else if (!_free_list_only) {
6055 assert(!r->is_young(), "we should not come across young regions");
6056
6057 if (r->is_humongous()) {
6058 // We ignore humongous regions. We left the humongous set unchanged.
6059 } else {
6060 // Objects that were compacted would have ended up on regions
6061 // that were previously old or free. Archive regions (which are
6062 // old) will not have been touched.
6063 assert(r->is_free() || r->is_old(), "invariant");
6064 // We now consider them old, so register as such. Leave
6065 // archive regions set that way, however, while still adding
6066 // them to the old set.
6067 if (!r->is_archive()) {
6068 r->set_old();
6069 }
6070 _old_set->add(r);
6071 }
6072 _total_used += r->used();
6073 }
6074
6075 return false;
6076 }
6077
6078 size_t total_used() {
6079 return _total_used;
6080 }
6081 };
6082
6083 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6084 assert_at_safepoint(true /* should_be_vm_thread */);
6085
6086 if (!free_list_only) {
6087 _young_list->empty_list();
6088 }
6089
6090 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6091 heap_region_iterate(&cl);
6092
6093 if (!free_list_only) {
6094 set_used(cl.total_used());
6095 if (_archive_allocator != NULL) {
6096 _archive_allocator->clear_used();
6097 }
6098 }
6099 assert(used_unlocked() == recalculate_used(),
6100 "inconsistent used_unlocked(), "
6101 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6102 used_unlocked(), recalculate_used());
6103 }
6104
6105 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6106 _refine_cte_cl->set_concurrent(concurrent);
6107 }
6108
6109 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6110 HeapRegion* hr = heap_region_containing(p);
6111 return hr->is_in(p);
6112 }
6113
6114 // Methods for the mutator alloc region
6115
6116 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6117 bool force) {
6118 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6119 assert(!force || g1_policy()->can_expand_young_list(),
6120 "if force is true we should be able to expand the young list");
6121 bool young_list_full = g1_policy()->is_young_list_full();
6122 if (force || !young_list_full) {
6123 HeapRegion* new_alloc_region = new_region(word_size,
6124 false /* is_old */,
6125 false /* do_expand */);
6126 if (new_alloc_region != NULL) {
6127 set_region_short_lived_locked(new_alloc_region);
6128 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6129 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6130 return new_alloc_region;
6131 }
6132 }
6133 return NULL;
6134 }
6135
6136 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6137 size_t allocated_bytes) {
6138 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6139 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6140
6141 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6142 increase_used(allocated_bytes);
6143 _hr_printer.retire(alloc_region);
6144 // We update the eden sizes here, when the region is retired,
6145 // instead of when it's allocated, since this is the point that its
6146 // used space has been recored in _summary_bytes_used.
6147 g1mm()->update_eden_size();
6148 }
6149
6150 // Methods for the GC alloc regions
6151
6152 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6153 uint count,
6154 InCSetState dest) {
6155 assert(FreeList_lock->owned_by_self(), "pre-condition");
6156
6157 if (count < g1_policy()->max_regions(dest)) {
6158 const bool is_survivor = (dest.is_young());
6159 HeapRegion* new_alloc_region = new_region(word_size,
6160 !is_survivor,
6161 true /* do_expand */);
6162 if (new_alloc_region != NULL) {
6163 // We really only need to do this for old regions given that we
6164 // should never scan survivors. But it doesn't hurt to do it
6165 // for survivors too.
6166 new_alloc_region->record_timestamp();
6167 if (is_survivor) {
6168 new_alloc_region->set_survivor();
6169 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6170 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6171 } else {
6172 new_alloc_region->set_old();
6173 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6174 check_bitmaps("Old Region Allocation", new_alloc_region);
6175 }
6176 bool during_im = collector_state()->during_initial_mark_pause();
6177 new_alloc_region->note_start_of_copying(during_im);
6178 return new_alloc_region;
6179 }
6180 }
6181 return NULL;
6182 }
6183
6184 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6185 size_t allocated_bytes,
6186 InCSetState dest) {
6187 bool during_im = collector_state()->during_initial_mark_pause();
6188 alloc_region->note_end_of_copying(during_im);
6189 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6190 if (dest.is_young()) {
6191 young_list()->add_survivor_region(alloc_region);
6192 } else {
6193 _old_set.add(alloc_region);
6194 }
6195 _hr_printer.retire(alloc_region);
6196 }
6197
6198 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6199 bool expanded = false;
6200 uint index = _hrm.find_highest_free(&expanded);
6201
6202 if (index != G1_NO_HRM_INDEX) {
6203 if (expanded) {
6204 ergo_verbose1(ErgoHeapSizing,
6205 "attempt heap expansion",
6206 ergo_format_reason("requested address range outside heap bounds")
6207 ergo_format_byte("region size"),
6208 HeapRegion::GrainWords * HeapWordSize);
6209 }
6210 _hrm.allocate_free_regions_starting_at(index, 1);
6211 return region_at(index);
6212 }
6213 return NULL;
6214 }
6215
6216 // Heap region set verification
6217
6218 class VerifyRegionListsClosure : public HeapRegionClosure {
6219 private:
6220 HeapRegionSet* _old_set;
6221 HeapRegionSet* _humongous_set;
6222 HeapRegionManager* _hrm;
6223
6224 public:
6225 HeapRegionSetCount _old_count;
6226 HeapRegionSetCount _humongous_count;
6227 HeapRegionSetCount _free_count;
6228
6229 VerifyRegionListsClosure(HeapRegionSet* old_set,
6230 HeapRegionSet* humongous_set,
6231 HeapRegionManager* hrm) :
6232 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6233 _old_count(), _humongous_count(), _free_count(){ }
6234
6235 bool doHeapRegion(HeapRegion* hr) {
6236 if (hr->is_continues_humongous()) {
6237 return false;
6238 }
6239
6240 if (hr->is_young()) {
6241 // TODO
6242 } else if (hr->is_starts_humongous()) {
6243 assert(hr->containing_set() == _humongous_set, "Heap region %u is starts humongous but not in humongous set.", hr->hrm_index());
6244 _humongous_count.increment(1u, hr->capacity());
6245 } else if (hr->is_empty()) {
6246 assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
6247 _free_count.increment(1u, hr->capacity());
6248 } else if (hr->is_old()) {
6249 assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
6250 _old_count.increment(1u, hr->capacity());
6251 } else {
6252 // There are no other valid region types. Check for one invalid
6253 // one we can identify: pinned without old or humongous set.
6254 assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
6255 ShouldNotReachHere();
6256 }
6257 return false;
6258 }
6259
6260 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6261 guarantee(old_set->length() == _old_count.length(), "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length());
6262 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), "Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6263 old_set->total_capacity_bytes(), _old_count.capacity());
6264
6265 guarantee(humongous_set->length() == _humongous_count.length(), "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length());
6266 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), "Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6267 humongous_set->total_capacity_bytes(), _humongous_count.capacity());
6268
6269 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());
6270 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), "Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6271 free_list->total_capacity_bytes(), _free_count.capacity());
6272 }
6273 };
6274
6275 void G1CollectedHeap::verify_region_sets() {
6276 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6277
6278 // First, check the explicit lists.
6279 _hrm.verify();
6280 {
6281 // Given that a concurrent operation might be adding regions to
6282 // the secondary free list we have to take the lock before
6283 // verifying it.
6284 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6285 _secondary_free_list.verify_list();
6286 }
6287
6288 // If a concurrent region freeing operation is in progress it will
6289 // be difficult to correctly attributed any free regions we come
6290 // across to the correct free list given that they might belong to
6291 // one of several (free_list, secondary_free_list, any local lists,
6292 // etc.). So, if that's the case we will skip the rest of the
6293 // verification operation. Alternatively, waiting for the concurrent
6294 // operation to complete will have a non-trivial effect on the GC's
6295 // operation (no concurrent operation will last longer than the
6296 // interval between two calls to verification) and it might hide
6297 // any issues that we would like to catch during testing.
6298 if (free_regions_coming()) {
6299 return;
6300 }
6301
6302 // Make sure we append the secondary_free_list on the free_list so
6303 // that all free regions we will come across can be safely
6304 // attributed to the free_list.
6305 append_secondary_free_list_if_not_empty_with_lock();
6306
6307 // Finally, make sure that the region accounting in the lists is
6308 // consistent with what we see in the heap.
6309
6310 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6311 heap_region_iterate(&cl);
6312 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6313 }
6314
6315 // Optimized nmethod scanning
6316
6317 class RegisterNMethodOopClosure: public OopClosure {
6318 G1CollectedHeap* _g1h;
6319 nmethod* _nm;
6320
6321 template <class T> void do_oop_work(T* p) {
6322 T heap_oop = oopDesc::load_heap_oop(p);
6323 if (!oopDesc::is_null(heap_oop)) {
6324 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6325 HeapRegion* hr = _g1h->heap_region_containing(obj);
6326 assert(!hr->is_continues_humongous(),
6327 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6328 " starting at " HR_FORMAT,
6329 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6330
6331 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6332 hr->add_strong_code_root_locked(_nm);
6333 }
6334 }
6335
6336 public:
6337 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6338 _g1h(g1h), _nm(nm) {}
6339
6340 void do_oop(oop* p) { do_oop_work(p); }
6341 void do_oop(narrowOop* p) { do_oop_work(p); }
6342 };
6343
6344 class UnregisterNMethodOopClosure: public OopClosure {
6345 G1CollectedHeap* _g1h;
6346 nmethod* _nm;
6347
6348 template <class T> void do_oop_work(T* p) {
6349 T heap_oop = oopDesc::load_heap_oop(p);
6350 if (!oopDesc::is_null(heap_oop)) {
6351 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6352 HeapRegion* hr = _g1h->heap_region_containing(obj);
6353 assert(!hr->is_continues_humongous(),
6354 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6355 " starting at " HR_FORMAT,
6356 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
6357
6358 hr->remove_strong_code_root(_nm);
6359 }
6360 }
6361
6362 public:
6363 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6364 _g1h(g1h), _nm(nm) {}
6365
6366 void do_oop(oop* p) { do_oop_work(p); }
6367 void do_oop(narrowOop* p) { do_oop_work(p); }
6368 };
6369
6370 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6371 CollectedHeap::register_nmethod(nm);
6372
6373 guarantee(nm != NULL, "sanity");
6374 RegisterNMethodOopClosure reg_cl(this, nm);
6375 nm->oops_do(®_cl);
6376 }
6377
6378 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6379 CollectedHeap::unregister_nmethod(nm);
6380
6381 guarantee(nm != NULL, "sanity");
6382 UnregisterNMethodOopClosure reg_cl(this, nm);
6383 nm->oops_do(®_cl, true);
6384 }
6385
6386 void G1CollectedHeap::purge_code_root_memory() {
6387 double purge_start = os::elapsedTime();
6388 G1CodeRootSet::purge();
6389 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6390 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6391 }
6392
6393 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6394 G1CollectedHeap* _g1h;
6395
6396 public:
6397 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6398 _g1h(g1h) {}
6399
6400 void do_code_blob(CodeBlob* cb) {
6401 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6402 if (nm == NULL) {
6403 return;
6404 }
6405
6406 if (ScavengeRootsInCode) {
6407 _g1h->register_nmethod(nm);
6408 }
6409 }
6410 };
6411
6412 void G1CollectedHeap::rebuild_strong_code_roots() {
6413 RebuildStrongCodeRootClosure blob_cl(this);
6414 CodeCache::blobs_do(&blob_cl);
6415 }