1 /*
2 * Copyright (c) 2001, 2017, 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 "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MarkSweep.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1YCTypes.hpp"
56 #include "gc/g1/heapRegion.inline.hpp"
57 #include "gc/g1/heapRegionRemSet.hpp"
58 #include "gc/g1/heapRegionSet.inline.hpp"
59 #include "gc/g1/suspendibleThreadSet.hpp"
60 #include "gc/g1/vm_operations_g1.hpp"
61 #include "gc/shared/gcHeapSummary.hpp"
62 #include "gc/shared/gcId.hpp"
63 #include "gc/shared/gcLocker.inline.hpp"
64 #include "gc/shared/gcTimer.hpp"
65 #include "gc/shared/gcTrace.hpp"
66 #include "gc/shared/gcTraceTime.inline.hpp"
67 #include "gc/shared/generationSpec.hpp"
68 #include "gc/shared/isGCActiveMark.hpp"
69 #include "gc/shared/preservedMarks.inline.hpp"
70 #include "gc/shared/referenceProcessor.inline.hpp"
71 #include "gc/shared/taskqueue.inline.hpp"
72 #include "logging/log.hpp"
73 #include "memory/allocation.hpp"
74 #include "memory/iterator.hpp"
75 #include "memory/resourceArea.hpp"
76 #include "oops/oop.inline.hpp"
77 #include "runtime/atomic.hpp"
78 #include "runtime/init.hpp"
79 #include "runtime/orderAccess.inline.hpp"
80 #include "runtime/vmThread.hpp"
81 #include "utilities/globalDefinitions.hpp"
82 #include "utilities/stack.inline.hpp"
83
84 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
85
86 // INVARIANTS/NOTES
87 //
88 // All allocation activity covered by the G1CollectedHeap interface is
89 // serialized by acquiring the HeapLock. This happens in mem_allocate
90 // and allocate_new_tlab, which are the "entry" points to the
91 // allocation code from the rest of the JVM. (Note that this does not
92 // apply to TLAB allocation, which is not part of this interface: it
93 // is done by clients of this interface.)
94
95 // Local to this file.
96
97 class RefineCardTableEntryClosure: public CardTableEntryClosure {
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure() : _concurrent(true) { }
101
102 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
103 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
104
105 if (_concurrent && SuspendibleThreadSet::should_yield()) {
106 // Caller will actually yield.
107 return false;
108 }
109 // Otherwise, we finished successfully; return true.
110 return true;
111 }
112
113 void set_concurrent(bool b) { _concurrent = b; }
114 };
115
116
117 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
118 private:
119 size_t _num_dirtied;
120 G1CollectedHeap* _g1h;
121 G1SATBCardTableLoggingModRefBS* _g1_bs;
122
123 HeapRegion* region_for_card(jbyte* card_ptr) const {
124 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
125 }
126
127 bool will_become_free(HeapRegion* hr) const {
128 // A region will be freed by free_collection_set if the region is in the
129 // collection set and has not had an evacuation failure.
130 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
131 }
132
133 public:
134 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
135 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
136
137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
138 HeapRegion* hr = region_for_card(card_ptr);
139
140 // Should only dirty cards in regions that won't be freed.
141 if (!will_become_free(hr)) {
142 *card_ptr = CardTableModRefBS::dirty_card_val();
143 _num_dirtied++;
144 }
145
146 return true;
147 }
148
149 size_t num_dirtied() const { return _num_dirtied; }
150 };
151
152
153 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
154 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
155 }
156
157 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
158 // The from card cache is not the memory that is actually committed. So we cannot
159 // take advantage of the zero_filled parameter.
160 reset_from_card_cache(start_idx, num_regions);
161 }
162
163 // Returns true if the reference points to an object that
164 // can move in an incremental collection.
165 bool G1CollectedHeap::is_scavengable(const void* p) {
166 HeapRegion* hr = heap_region_containing(p);
167 return !hr->is_pinned();
168 }
169
170 // Private methods.
171
172 HeapRegion*
173 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
174 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
175 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
176 if (!_secondary_free_list.is_empty()) {
177 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
178 "secondary_free_list has %u entries",
179 _secondary_free_list.length());
180 // It looks as if there are free regions available on the
181 // secondary_free_list. Let's move them to the free_list and try
182 // again to allocate from it.
183 append_secondary_free_list();
184
185 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
186 "empty we should have moved at least one entry to the free_list");
187 HeapRegion* res = _hrm.allocate_free_region(is_old);
188 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
189 "allocated " HR_FORMAT " from secondary_free_list",
190 HR_FORMAT_PARAMS(res));
191 return res;
192 }
193
194 // Wait here until we get notified either when (a) there are no
195 // more free regions coming or (b) some regions have been moved on
196 // the secondary_free_list.
197 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
198 }
199
200 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
201 "could not allocate from secondary_free_list");
202 return NULL;
203 }
204
205 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
206 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
207 "the only time we use this to allocate a humongous region is "
208 "when we are allocating a single humongous region");
209
210 HeapRegion* res;
211 if (G1StressConcRegionFreeing) {
212 if (!_secondary_free_list.is_empty()) {
213 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
214 "forced to look at the secondary_free_list");
215 res = new_region_try_secondary_free_list(is_old);
216 if (res != NULL) {
217 return res;
218 }
219 }
220 }
221
222 res = _hrm.allocate_free_region(is_old);
223
224 if (res == NULL) {
225 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
226 "res == NULL, trying the secondary_free_list");
227 res = new_region_try_secondary_free_list(is_old);
228 }
229 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
230 // Currently, only attempts to allocate GC alloc regions set
231 // do_expand to true. So, we should only reach here during a
232 // safepoint. If this assumption changes we might have to
233 // reconsider the use of _expand_heap_after_alloc_failure.
234 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
235
236 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
237 word_size * HeapWordSize);
238
239 if (expand(word_size * HeapWordSize)) {
240 // Given that expand() succeeded in expanding the heap, and we
241 // always expand the heap by an amount aligned to the heap
242 // region size, the free list should in theory not be empty.
243 // In either case allocate_free_region() will check for NULL.
244 res = _hrm.allocate_free_region(is_old);
245 } else {
246 _expand_heap_after_alloc_failure = false;
247 }
248 }
249 return res;
250 }
251
252 HeapWord*
253 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
254 uint num_regions,
255 size_t word_size,
256 AllocationContext_t context) {
257 assert(first != G1_NO_HRM_INDEX, "pre-condition");
258 assert(is_humongous(word_size), "word_size should be humongous");
259 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
260
261 // Index of last region in the series.
262 uint last = first + num_regions - 1;
263
264 // We need to initialize the region(s) we just discovered. This is
265 // a bit tricky given that it can happen concurrently with
266 // refinement threads refining cards on these regions and
267 // potentially wanting to refine the BOT as they are scanning
268 // those cards (this can happen shortly after a cleanup; see CR
269 // 6991377). So we have to set up the region(s) carefully and in
270 // a specific order.
271
272 // The word size sum of all the regions we will allocate.
273 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
274 assert(word_size <= word_size_sum, "sanity");
275
276 // This will be the "starts humongous" region.
277 HeapRegion* first_hr = region_at(first);
278 // The header of the new object will be placed at the bottom of
279 // the first region.
280 HeapWord* new_obj = first_hr->bottom();
281 // This will be the new top of the new object.
282 HeapWord* obj_top = new_obj + word_size;
283
284 // First, we need to zero the header of the space that we will be
285 // allocating. When we update top further down, some refinement
286 // threads might try to scan the region. By zeroing the header we
287 // ensure that any thread that will try to scan the region will
288 // come across the zero klass word and bail out.
289 //
290 // NOTE: It would not have been correct to have used
291 // CollectedHeap::fill_with_object() and make the space look like
292 // an int array. The thread that is doing the allocation will
293 // later update the object header to a potentially different array
294 // type and, for a very short period of time, the klass and length
295 // fields will be inconsistent. This could cause a refinement
296 // thread to calculate the object size incorrectly.
297 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
298
299 // Next, pad out the unused tail of the last region with filler
300 // objects, for improved usage accounting.
301 // How many words we use for filler objects.
302 size_t word_fill_size = word_size_sum - word_size;
303
304 // How many words memory we "waste" which cannot hold a filler object.
305 size_t words_not_fillable = 0;
306
307 if (word_fill_size >= min_fill_size()) {
308 fill_with_objects(obj_top, word_fill_size);
309 } else if (word_fill_size > 0) {
310 // We have space to fill, but we cannot fit an object there.
311 words_not_fillable = word_fill_size;
312 word_fill_size = 0;
313 }
314
315 // We will set up the first region as "starts humongous". This
316 // will also update the BOT covering all the regions to reflect
317 // that there is a single object that starts at the bottom of the
318 // first region.
319 first_hr->set_starts_humongous(obj_top, word_fill_size);
320 first_hr->set_allocation_context(context);
321 // Then, if there are any, we will set up the "continues
322 // humongous" regions.
323 HeapRegion* hr = NULL;
324 for (uint i = first + 1; i <= last; ++i) {
325 hr = region_at(i);
326 hr->set_continues_humongous(first_hr);
327 hr->set_allocation_context(context);
328 }
329
330 // Up to this point no concurrent thread would have been able to
331 // do any scanning on any region in this series. All the top
332 // fields still point to bottom, so the intersection between
333 // [bottom,top] and [card_start,card_end] will be empty. Before we
334 // update the top fields, we'll do a storestore to make sure that
335 // no thread sees the update to top before the zeroing of the
336 // object header and the BOT initialization.
337 OrderAccess::storestore();
338
339 // Now, we will update the top fields of the "continues humongous"
340 // regions except the last one.
341 for (uint i = first; i < last; ++i) {
342 hr = region_at(i);
343 hr->set_top(hr->end());
344 }
345
346 hr = region_at(last);
347 // If we cannot fit a filler object, we must set top to the end
348 // of the humongous object, otherwise we cannot iterate the heap
349 // and the BOT will not be complete.
350 hr->set_top(hr->end() - words_not_fillable);
351
352 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
353 "obj_top should be in last region");
354
355 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
356
357 assert(words_not_fillable == 0 ||
358 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
359 "Miscalculation in humongous allocation");
360
361 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
362
363 for (uint i = first; i <= last; ++i) {
364 hr = region_at(i);
365 _humongous_set.add(hr);
366 _hr_printer.alloc(hr);
367 }
368
369 return new_obj;
370 }
371
372 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
373 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
374 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
375 }
376
377 // If could fit into free regions w/o expansion, try.
378 // Otherwise, if can expand, do so.
379 // Otherwise, if using ex regions might help, try with ex given back.
380 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
381 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
382
383 _verifier->verify_region_sets_optional();
384
385 uint first = G1_NO_HRM_INDEX;
386 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
387
388 if (obj_regions == 1) {
389 // Only one region to allocate, try to use a fast path by directly allocating
390 // from the free lists. Do not try to expand here, we will potentially do that
391 // later.
392 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
393 if (hr != NULL) {
394 first = hr->hrm_index();
395 }
396 } else {
397 // We can't allocate humongous regions spanning more than one region while
398 // cleanupComplete() is running, since some of the regions we find to be
399 // empty might not yet be added to the free list. It is not straightforward
400 // to know in which list they are on so that we can remove them. We only
401 // need to do this if we need to allocate more than one region to satisfy the
402 // current humongous allocation request. If we are only allocating one region
403 // we use the one-region region allocation code (see above), that already
404 // potentially waits for regions from the secondary free list.
405 wait_while_free_regions_coming();
406 append_secondary_free_list_if_not_empty_with_lock();
407
408 // Policy: Try only empty regions (i.e. already committed first). Maybe we
409 // are lucky enough to find some.
410 first = _hrm.find_contiguous_only_empty(obj_regions);
411 if (first != G1_NO_HRM_INDEX) {
412 _hrm.allocate_free_regions_starting_at(first, obj_regions);
413 }
414 }
415
416 if (first == G1_NO_HRM_INDEX) {
417 // Policy: We could not find enough regions for the humongous object in the
418 // free list. Look through the heap to find a mix of free and uncommitted regions.
419 // If so, try expansion.
420 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
421 if (first != G1_NO_HRM_INDEX) {
422 // We found something. Make sure these regions are committed, i.e. expand
423 // the heap. Alternatively we could do a defragmentation GC.
424 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
425 word_size * HeapWordSize);
426
427 _hrm.expand_at(first, obj_regions, workers());
428 g1_policy()->record_new_heap_size(num_regions());
429
430 #ifdef ASSERT
431 for (uint i = first; i < first + obj_regions; ++i) {
432 HeapRegion* hr = region_at(i);
433 assert(hr->is_free(), "sanity");
434 assert(hr->is_empty(), "sanity");
435 assert(is_on_master_free_list(hr), "sanity");
436 }
437 #endif
438 _hrm.allocate_free_regions_starting_at(first, obj_regions);
439 } else {
440 // Policy: Potentially trigger a defragmentation GC.
441 }
442 }
443
444 HeapWord* result = NULL;
445 if (first != G1_NO_HRM_INDEX) {
446 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
447 word_size, context);
448 assert(result != NULL, "it should always return a valid result");
449
450 // A successful humongous object allocation changes the used space
451 // information of the old generation so we need to recalculate the
452 // sizes and update the jstat counters here.
453 g1mm()->update_sizes();
454 }
455
456 _verifier->verify_region_sets_optional();
457
458 return result;
459 }
460
461 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
462 assert_heap_not_locked_and_not_at_safepoint();
463 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
464
465 uint dummy_gc_count_before;
466 uint dummy_gclocker_retry_count = 0;
467 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
468 }
469
470 HeapWord*
471 G1CollectedHeap::mem_allocate(size_t word_size,
472 bool* gc_overhead_limit_was_exceeded) {
473 assert_heap_not_locked_and_not_at_safepoint();
474
475 // Loop until the allocation is satisfied, or unsatisfied after GC.
476 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
477 uint gc_count_before;
478
479 HeapWord* result = NULL;
480 if (!is_humongous(word_size)) {
481 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
482 } else {
483 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
484 }
485 if (result != NULL) {
486 return result;
487 }
488
489 // Create the garbage collection operation...
490 VM_G1CollectForAllocation op(gc_count_before, word_size);
491 op.set_allocation_context(AllocationContext::current());
492
493 // ...and get the VM thread to execute it.
494 VMThread::execute(&op);
495
496 if (op.prologue_succeeded() && op.pause_succeeded()) {
497 // If the operation was successful we'll return the result even
498 // if it is NULL. If the allocation attempt failed immediately
499 // after a Full GC, it's unlikely we'll be able to allocate now.
500 HeapWord* result = op.result();
501 if (result != NULL && !is_humongous(word_size)) {
502 // Allocations that take place on VM operations do not do any
503 // card dirtying and we have to do it here. We only have to do
504 // this for non-humongous allocations, though.
505 dirty_young_block(result, word_size);
506 }
507 return result;
508 } else {
509 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
510 return NULL;
511 }
512 assert(op.result() == NULL,
513 "the result should be NULL if the VM op did not succeed");
514 }
515
516 // Give a warning if we seem to be looping forever.
517 if ((QueuedAllocationWarningCount > 0) &&
518 (try_count % QueuedAllocationWarningCount == 0)) {
519 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
520 }
521 }
522
523 ShouldNotReachHere();
524 return NULL;
525 }
526
527 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
528 AllocationContext_t context,
529 uint* gc_count_before_ret,
530 uint* gclocker_retry_count_ret) {
531 // Make sure you read the note in attempt_allocation_humongous().
532
533 assert_heap_not_locked_and_not_at_safepoint();
534 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
535 "be called for humongous allocation requests");
536
537 // We should only get here after the first-level allocation attempt
538 // (attempt_allocation()) failed to allocate.
539
540 // We will loop until a) we manage to successfully perform the
541 // allocation or b) we successfully schedule a collection which
542 // fails to perform the allocation. b) is the only case when we'll
543 // return NULL.
544 HeapWord* result = NULL;
545 for (int try_count = 1; /* we'll return */; try_count += 1) {
546 bool should_try_gc;
547 uint gc_count_before;
548
549 {
550 MutexLockerEx x(Heap_lock);
551 result = _allocator->attempt_allocation_locked(word_size, context);
552 if (result != NULL) {
553 return result;
554 }
555
556 if (GCLocker::is_active_and_needs_gc()) {
557 if (g1_policy()->can_expand_young_list()) {
558 // No need for an ergo verbose message here,
559 // can_expand_young_list() does this when it returns true.
560 result = _allocator->attempt_allocation_force(word_size, context);
561 if (result != NULL) {
562 return result;
563 }
564 }
565 should_try_gc = false;
566 } else {
567 // The GCLocker may not be active but the GCLocker initiated
568 // GC may not yet have been performed (GCLocker::needs_gc()
569 // returns true). In this case we do not try this GC and
570 // wait until the GCLocker initiated GC is performed, and
571 // then retry the allocation.
572 if (GCLocker::needs_gc()) {
573 should_try_gc = false;
574 } else {
575 // Read the GC count while still holding the Heap_lock.
576 gc_count_before = total_collections();
577 should_try_gc = true;
578 }
579 }
580 }
581
582 if (should_try_gc) {
583 bool succeeded;
584 result = do_collection_pause(word_size, gc_count_before, &succeeded,
585 GCCause::_g1_inc_collection_pause);
586 if (result != NULL) {
587 assert(succeeded, "only way to get back a non-NULL result");
588 return result;
589 }
590
591 if (succeeded) {
592 // If we get here we successfully scheduled a collection which
593 // failed to allocate. No point in trying to allocate
594 // further. We'll just return NULL.
595 MutexLockerEx x(Heap_lock);
596 *gc_count_before_ret = total_collections();
597 return NULL;
598 }
599 } else {
600 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
601 MutexLockerEx x(Heap_lock);
602 *gc_count_before_ret = total_collections();
603 return NULL;
604 }
605 // The GCLocker is either active or the GCLocker initiated
606 // GC has not yet been performed. Stall until it is and
607 // then retry the allocation.
608 GCLocker::stall_until_clear();
609 (*gclocker_retry_count_ret) += 1;
610 }
611
612 // We can reach here if we were unsuccessful in scheduling a
613 // collection (because another thread beat us to it) or if we were
614 // stalled due to the GC locker. In either can we should retry the
615 // allocation attempt in case another thread successfully
616 // performed a collection and reclaimed enough space. We do the
617 // first attempt (without holding the Heap_lock) here and the
618 // follow-on attempt will be at the start of the next loop
619 // iteration (after taking the Heap_lock).
620 result = _allocator->attempt_allocation(word_size, context);
621 if (result != NULL) {
622 return result;
623 }
624
625 // Give a warning if we seem to be looping forever.
626 if ((QueuedAllocationWarningCount > 0) &&
627 (try_count % QueuedAllocationWarningCount == 0)) {
628 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
629 "retries %d times", try_count);
630 }
631 }
632
633 ShouldNotReachHere();
634 return NULL;
635 }
636
637 void G1CollectedHeap::begin_archive_alloc_range() {
638 assert_at_safepoint(true /* should_be_vm_thread */);
639 if (_archive_allocator == NULL) {
640 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
641 }
642 }
643
644 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
645 // Allocations in archive regions cannot be of a size that would be considered
646 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
647 // may be different at archive-restore time.
648 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
649 }
650
651 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
652 assert_at_safepoint(true /* should_be_vm_thread */);
653 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
654 if (is_archive_alloc_too_large(word_size)) {
655 return NULL;
656 }
657 return _archive_allocator->archive_mem_allocate(word_size);
658 }
659
660 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
661 size_t end_alignment_in_bytes) {
662 assert_at_safepoint(true /* should_be_vm_thread */);
663 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
664
665 // Call complete_archive to do the real work, filling in the MemRegion
666 // array with the archive regions.
667 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
668 delete _archive_allocator;
669 _archive_allocator = NULL;
670 }
671
672 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
673 assert(ranges != NULL, "MemRegion array NULL");
674 assert(count != 0, "No MemRegions provided");
675 MemRegion reserved = _hrm.reserved();
676 for (size_t i = 0; i < count; i++) {
677 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
678 return false;
679 }
680 }
681 return true;
682 }
683
684 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
685 assert(!is_init_completed(), "Expect to be called at JVM init time");
686 assert(ranges != NULL, "MemRegion array NULL");
687 assert(count != 0, "No MemRegions provided");
688 MutexLockerEx x(Heap_lock);
689
690 MemRegion reserved = _hrm.reserved();
691 HeapWord* prev_last_addr = NULL;
692 HeapRegion* prev_last_region = NULL;
693
694 // Temporarily disable pretouching of heap pages. This interface is used
695 // when mmap'ing archived heap data in, so pre-touching is wasted.
696 FlagSetting fs(AlwaysPreTouch, false);
697
698 // Enable archive object checking used by G1MarkSweep. We have to let it know
699 // about each archive range, so that objects in those ranges aren't marked.
700 G1ArchiveAllocator::enable_archive_object_check();
701
702 // For each specified MemRegion range, allocate the corresponding G1
703 // regions and mark them as archive regions. We expect the ranges in
704 // ascending starting address order, without overlap.
705 for (size_t i = 0; i < count; i++) {
706 MemRegion curr_range = ranges[i];
707 HeapWord* start_address = curr_range.start();
708 size_t word_size = curr_range.word_size();
709 HeapWord* last_address = curr_range.last();
710 size_t commits = 0;
711
712 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
713 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
714 p2i(start_address), p2i(last_address));
715 guarantee(start_address > prev_last_addr,
716 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
717 p2i(start_address), p2i(prev_last_addr));
718 prev_last_addr = last_address;
719
720 // Check for ranges that start in the same G1 region in which the previous
721 // range ended, and adjust the start address so we don't try to allocate
722 // the same region again. If the current range is entirely within that
723 // region, skip it, just adjusting the recorded top.
724 HeapRegion* start_region = _hrm.addr_to_region(start_address);
725 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
726 start_address = start_region->end();
727 if (start_address > last_address) {
728 increase_used(word_size * HeapWordSize);
729 start_region->set_top(last_address + 1);
730 continue;
731 }
732 start_region->set_top(start_address);
733 curr_range = MemRegion(start_address, last_address + 1);
734 start_region = _hrm.addr_to_region(start_address);
735 }
736
737 // Perform the actual region allocation, exiting if it fails.
738 // Then note how much new space we have allocated.
739 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
740 return false;
741 }
742 increase_used(word_size * HeapWordSize);
743 if (commits != 0) {
744 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
745 HeapRegion::GrainWords * HeapWordSize * commits);
746
747 }
748
749 // Mark each G1 region touched by the range as archive, add it to the old set,
750 // and set the allocation context and top.
751 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
752 HeapRegion* last_region = _hrm.addr_to_region(last_address);
753 prev_last_region = last_region;
754
755 while (curr_region != NULL) {
756 assert(curr_region->is_empty() && !curr_region->is_pinned(),
757 "Region already in use (index %u)", curr_region->hrm_index());
758 curr_region->set_allocation_context(AllocationContext::system());
759 curr_region->set_archive();
760 _hr_printer.alloc(curr_region);
761 _old_set.add(curr_region);
762 if (curr_region != last_region) {
763 curr_region->set_top(curr_region->end());
764 curr_region = _hrm.next_region_in_heap(curr_region);
765 } else {
766 curr_region->set_top(last_address + 1);
767 curr_region = NULL;
768 }
769 }
770
771 // Notify mark-sweep of the archive range.
772 G1ArchiveAllocator::set_range_archive(curr_range, true);
773 }
774 return true;
775 }
776
777 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
778 assert(!is_init_completed(), "Expect to be called at JVM init time");
779 assert(ranges != NULL, "MemRegion array NULL");
780 assert(count != 0, "No MemRegions provided");
781 MemRegion reserved = _hrm.reserved();
782 HeapWord *prev_last_addr = NULL;
783 HeapRegion* prev_last_region = NULL;
784
785 // For each MemRegion, create filler objects, if needed, in the G1 regions
786 // that contain the address range. The address range actually within the
787 // MemRegion will not be modified. That is assumed to have been initialized
788 // elsewhere, probably via an mmap of archived heap data.
789 MutexLockerEx x(Heap_lock);
790 for (size_t i = 0; i < count; i++) {
791 HeapWord* start_address = ranges[i].start();
792 HeapWord* last_address = ranges[i].last();
793
794 assert(reserved.contains(start_address) && reserved.contains(last_address),
795 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
796 p2i(start_address), p2i(last_address));
797 assert(start_address > prev_last_addr,
798 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
799 p2i(start_address), p2i(prev_last_addr));
800
801 HeapRegion* start_region = _hrm.addr_to_region(start_address);
802 HeapRegion* last_region = _hrm.addr_to_region(last_address);
803 HeapWord* bottom_address = start_region->bottom();
804
805 // Check for a range beginning in the same region in which the
806 // previous one ended.
807 if (start_region == prev_last_region) {
808 bottom_address = prev_last_addr + 1;
809 }
810
811 // Verify that the regions were all marked as archive regions by
812 // alloc_archive_regions.
813 HeapRegion* curr_region = start_region;
814 while (curr_region != NULL) {
815 guarantee(curr_region->is_archive(),
816 "Expected archive region at index %u", curr_region->hrm_index());
817 if (curr_region != last_region) {
818 curr_region = _hrm.next_region_in_heap(curr_region);
819 } else {
820 curr_region = NULL;
821 }
822 }
823
824 prev_last_addr = last_address;
825 prev_last_region = last_region;
826
827 // Fill the memory below the allocated range with dummy object(s),
828 // if the region bottom does not match the range start, or if the previous
829 // range ended within the same G1 region, and there is a gap.
830 if (start_address != bottom_address) {
831 size_t fill_size = pointer_delta(start_address, bottom_address);
832 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
833 increase_used(fill_size * HeapWordSize);
834 }
835 }
836 }
837
838 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
839 uint* gc_count_before_ret,
840 uint* gclocker_retry_count_ret) {
841 assert_heap_not_locked_and_not_at_safepoint();
842 assert(!is_humongous(word_size), "attempt_allocation() should not "
843 "be called for humongous allocation requests");
844
845 AllocationContext_t context = AllocationContext::current();
846 HeapWord* result = _allocator->attempt_allocation(word_size, context);
847
848 if (result == NULL) {
849 result = attempt_allocation_slow(word_size,
850 context,
851 gc_count_before_ret,
852 gclocker_retry_count_ret);
853 }
854 assert_heap_not_locked();
855 if (result != NULL) {
856 dirty_young_block(result, word_size);
857 }
858 return result;
859 }
860
861 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
862 assert(!is_init_completed(), "Expect to be called at JVM init time");
863 assert(ranges != NULL, "MemRegion array NULL");
864 assert(count != 0, "No MemRegions provided");
865 MemRegion reserved = _hrm.reserved();
866 HeapWord* prev_last_addr = NULL;
867 HeapRegion* prev_last_region = NULL;
868 size_t size_used = 0;
869 size_t uncommitted_regions = 0;
870
871 // For each Memregion, free the G1 regions that constitute it, and
872 // notify mark-sweep that the range is no longer to be considered 'archive.'
873 MutexLockerEx x(Heap_lock);
874 for (size_t i = 0; i < count; i++) {
875 HeapWord* start_address = ranges[i].start();
876 HeapWord* last_address = ranges[i].last();
877
878 assert(reserved.contains(start_address) && reserved.contains(last_address),
879 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
880 p2i(start_address), p2i(last_address));
881 assert(start_address > prev_last_addr,
882 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
883 p2i(start_address), p2i(prev_last_addr));
884 size_used += ranges[i].byte_size();
885 prev_last_addr = last_address;
886
887 HeapRegion* start_region = _hrm.addr_to_region(start_address);
888 HeapRegion* last_region = _hrm.addr_to_region(last_address);
889
890 // Check for ranges that start in the same G1 region in which the previous
891 // range ended, and adjust the start address so we don't try to free
892 // the same region again. If the current range is entirely within that
893 // region, skip it.
894 if (start_region == prev_last_region) {
895 start_address = start_region->end();
896 if (start_address > last_address) {
897 continue;
898 }
899 start_region = _hrm.addr_to_region(start_address);
900 }
901 prev_last_region = last_region;
902
903 // After verifying that each region was marked as an archive region by
904 // alloc_archive_regions, set it free and empty and uncommit it.
905 HeapRegion* curr_region = start_region;
906 while (curr_region != NULL) {
907 guarantee(curr_region->is_archive(),
908 "Expected archive region at index %u", curr_region->hrm_index());
909 uint curr_index = curr_region->hrm_index();
910 _old_set.remove(curr_region);
911 curr_region->set_free();
912 curr_region->set_top(curr_region->bottom());
913 if (curr_region != last_region) {
914 curr_region = _hrm.next_region_in_heap(curr_region);
915 } else {
916 curr_region = NULL;
917 }
918 _hrm.shrink_at(curr_index, 1);
919 uncommitted_regions++;
920 }
921
922 // Notify mark-sweep that this is no longer an archive range.
923 G1ArchiveAllocator::set_range_archive(ranges[i], false);
924 }
925
926 if (uncommitted_regions != 0) {
927 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
928 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
929 }
930 decrease_used(size_used);
931 }
932
933 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
934 uint* gc_count_before_ret,
935 uint* gclocker_retry_count_ret) {
936 // The structure of this method has a lot of similarities to
937 // attempt_allocation_slow(). The reason these two were not merged
938 // into a single one is that such a method would require several "if
939 // allocation is not humongous do this, otherwise do that"
940 // conditional paths which would obscure its flow. In fact, an early
941 // version of this code did use a unified method which was harder to
942 // follow and, as a result, it had subtle bugs that were hard to
943 // track down. So keeping these two methods separate allows each to
944 // be more readable. It will be good to keep these two in sync as
945 // much as possible.
946
947 assert_heap_not_locked_and_not_at_safepoint();
948 assert(is_humongous(word_size), "attempt_allocation_humongous() "
949 "should only be called for humongous allocations");
950
951 // Humongous objects can exhaust the heap quickly, so we should check if we
952 // need to start a marking cycle at each humongous object allocation. We do
953 // the check before we do the actual allocation. The reason for doing it
954 // before the allocation is that we avoid having to keep track of the newly
955 // allocated memory while we do a GC.
956 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
957 word_size)) {
958 collect(GCCause::_g1_humongous_allocation);
959 }
960
961 // We will loop until a) we manage to successfully perform the
962 // allocation or b) we successfully schedule a collection which
963 // fails to perform the allocation. b) is the only case when we'll
964 // return NULL.
965 HeapWord* result = NULL;
966 for (int try_count = 1; /* we'll return */; try_count += 1) {
967 bool should_try_gc;
968 uint gc_count_before;
969
970 {
971 MutexLockerEx x(Heap_lock);
972
973 // Given that humongous objects are not allocated in young
974 // regions, we'll first try to do the allocation without doing a
975 // collection hoping that there's enough space in the heap.
976 result = humongous_obj_allocate(word_size, AllocationContext::current());
977 if (result != NULL) {
978 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
979 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
980 return result;
981 }
982
983 if (GCLocker::is_active_and_needs_gc()) {
984 should_try_gc = false;
985 } else {
986 // The GCLocker may not be active but the GCLocker initiated
987 // GC may not yet have been performed (GCLocker::needs_gc()
988 // returns true). In this case we do not try this GC and
989 // wait until the GCLocker initiated GC is performed, and
990 // then retry the allocation.
991 if (GCLocker::needs_gc()) {
992 should_try_gc = false;
993 } else {
994 // Read the GC count while still holding the Heap_lock.
995 gc_count_before = total_collections();
996 should_try_gc = true;
997 }
998 }
999 }
1000
1001 if (should_try_gc) {
1002 // If we failed to allocate the humongous object, we should try to
1003 // do a collection pause (if we're allowed) in case it reclaims
1004 // enough space for the allocation to succeed after the pause.
1005
1006 bool succeeded;
1007 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1008 GCCause::_g1_humongous_allocation);
1009 if (result != NULL) {
1010 assert(succeeded, "only way to get back a non-NULL result");
1011 return result;
1012 }
1013
1014 if (succeeded) {
1015 // If we get here we successfully scheduled a collection which
1016 // failed to allocate. No point in trying to allocate
1017 // further. We'll just return NULL.
1018 MutexLockerEx x(Heap_lock);
1019 *gc_count_before_ret = total_collections();
1020 return NULL;
1021 }
1022 } else {
1023 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1024 MutexLockerEx x(Heap_lock);
1025 *gc_count_before_ret = total_collections();
1026 return NULL;
1027 }
1028 // The GCLocker is either active or the GCLocker initiated
1029 // GC has not yet been performed. Stall until it is and
1030 // then retry the allocation.
1031 GCLocker::stall_until_clear();
1032 (*gclocker_retry_count_ret) += 1;
1033 }
1034
1035 // We can reach here if we were unsuccessful in scheduling a
1036 // collection (because another thread beat us to it) or if we were
1037 // stalled due to the GC locker. In either can we should retry the
1038 // allocation attempt in case another thread successfully
1039 // performed a collection and reclaimed enough space. Give a
1040 // warning if we seem to be looping forever.
1041
1042 if ((QueuedAllocationWarningCount > 0) &&
1043 (try_count % QueuedAllocationWarningCount == 0)) {
1044 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1045 "retries %d times", try_count);
1046 }
1047 }
1048
1049 ShouldNotReachHere();
1050 return NULL;
1051 }
1052
1053 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1054 AllocationContext_t context,
1055 bool expect_null_mutator_alloc_region) {
1056 assert_at_safepoint(true /* should_be_vm_thread */);
1057 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1058 "the current alloc region was unexpectedly found to be non-NULL");
1059
1060 if (!is_humongous(word_size)) {
1061 return _allocator->attempt_allocation_locked(word_size, context);
1062 } else {
1063 HeapWord* result = humongous_obj_allocate(word_size, context);
1064 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1065 collector_state()->set_initiate_conc_mark_if_possible(true);
1066 }
1067 return result;
1068 }
1069
1070 ShouldNotReachHere();
1071 }
1072
1073 class PostMCRemSetClearClosure: public HeapRegionClosure {
1074 G1CollectedHeap* _g1h;
1075 ModRefBarrierSet* _mr_bs;
1076 public:
1077 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1078 _g1h(g1h), _mr_bs(mr_bs) {}
1079
1080 bool doHeapRegion(HeapRegion* r) {
1081 HeapRegionRemSet* hrrs = r->rem_set();
1082
1083 _g1h->reset_gc_time_stamps(r);
1084
1085 if (r->is_continues_humongous()) {
1086 // We'll assert that the strong code root list and RSet is empty
1087 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1088 assert(hrrs->occupied() == 0, "RSet should be empty");
1089 } else {
1090 hrrs->clear();
1091 }
1092 // You might think here that we could clear just the cards
1093 // corresponding to the used region. But no: if we leave a dirty card
1094 // in a region we might allocate into, then it would prevent that card
1095 // from being enqueued, and cause it to be missed.
1096 // Re: the performance cost: we shouldn't be doing full GC anyway!
1097 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1098
1099 return false;
1100 }
1101 };
1102
1103 void G1CollectedHeap::clear_rsets_post_compaction() {
1104 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1105 heap_region_iterate(&rs_clear);
1106 }
1107
1108 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1109 G1CollectedHeap* _g1h;
1110 UpdateRSOopClosure _cl;
1111 public:
1112 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1113 _cl(g1->g1_rem_set(), worker_i),
1114 _g1h(g1)
1115 { }
1116
1117 bool doHeapRegion(HeapRegion* r) {
1118 if (!r->is_continues_humongous()) {
1119 _cl.set_from(r);
1120 r->oop_iterate(&_cl);
1121 }
1122 return false;
1123 }
1124 };
1125
1126 class ParRebuildRSTask: public AbstractGangTask {
1127 G1CollectedHeap* _g1;
1128 HeapRegionClaimer _hrclaimer;
1129
1130 public:
1131 ParRebuildRSTask(G1CollectedHeap* g1) :
1132 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1133
1134 void work(uint worker_id) {
1135 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1136 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1137 }
1138 };
1139
1140 class PostCompactionPrinterClosure: public HeapRegionClosure {
1141 private:
1142 G1HRPrinter* _hr_printer;
1143 public:
1144 bool doHeapRegion(HeapRegion* hr) {
1145 assert(!hr->is_young(), "not expecting to find young regions");
1146 _hr_printer->post_compaction(hr);
1147 return false;
1148 }
1149
1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151 : _hr_printer(hr_printer) { }
1152 };
1153
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155 if (_hr_printer.is_active()) {
1156 PostCompactionPrinterClosure cl(hr_printer());
1157 heap_region_iterate(&cl);
1158 }
1159
1160 }
1161
1162 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1163 bool clear_all_soft_refs) {
1164 assert_at_safepoint(true /* should_be_vm_thread */);
1165
1166 if (GCLocker::check_active_before_gc()) {
1167 return false;
1168 }
1169
1170 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1171 gc_timer->register_gc_start();
1172
1173 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1174 GCIdMark gc_id_mark;
1175 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1176
1177 SvcGCMarker sgcm(SvcGCMarker::FULL);
1178 ResourceMark rm;
1179
1180 print_heap_before_gc();
1181 print_heap_regions();
1182 trace_heap_before_gc(gc_tracer);
1183
1184 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1185
1186 _verifier->verify_region_sets_optional();
1187
1188 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1189 collector_policy()->should_clear_all_soft_refs();
1190
1191 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1192
1193 {
1194 IsGCActiveMark x;
1195
1196 // Timing
1197 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1198 GCTraceCPUTime tcpu;
1199
1200 {
1201 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1202 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1203 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1204
1205 G1HeapTransition heap_transition(this);
1206 g1_policy()->record_full_collection_start();
1207
1208 // Note: When we have a more flexible GC logging framework that
1209 // allows us to add optional attributes to a GC log record we
1210 // could consider timing and reporting how long we wait in the
1211 // following two methods.
1212 wait_while_free_regions_coming();
1213 // If we start the compaction before the CM threads finish
1214 // scanning the root regions we might trip them over as we'll
1215 // be moving objects / updating references. So let's wait until
1216 // they are done. By telling them to abort, they should complete
1217 // early.
1218 _cm->root_regions()->abort();
1219 _cm->root_regions()->wait_until_scan_finished();
1220 append_secondary_free_list_if_not_empty_with_lock();
1221
1222 gc_prologue(true);
1223 increment_total_collections(true /* full gc */);
1224 increment_old_marking_cycles_started();
1225
1226 assert(used() == recalculate_used(), "Should be equal");
1227
1228 _verifier->verify_before_gc();
1229
1230 _verifier->check_bitmaps("Full GC Start");
1231 pre_full_gc_dump(gc_timer);
1232
1233 #if defined(COMPILER2) || INCLUDE_JVMCI
1234 DerivedPointerTable::clear();
1235 #endif
1236
1237 // Disable discovery and empty the discovered lists
1238 // for the CM ref processor.
1239 ref_processor_cm()->disable_discovery();
1240 ref_processor_cm()->abandon_partial_discovery();
1241 ref_processor_cm()->verify_no_references_recorded();
1242
1243 // Abandon current iterations of concurrent marking and concurrent
1244 // refinement, if any are in progress.
1245 concurrent_mark()->abort();
1246
1247 // Make sure we'll choose a new allocation region afterwards.
1248 _allocator->release_mutator_alloc_region();
1249 _allocator->abandon_gc_alloc_regions();
1250 g1_rem_set()->cleanupHRRS();
1251
1252 // We may have added regions to the current incremental collection
1253 // set between the last GC or pause and now. We need to clear the
1254 // incremental collection set and then start rebuilding it afresh
1255 // after this full GC.
1256 abandon_collection_set(collection_set());
1257
1258 tear_down_region_sets(false /* free_list_only */);
1259 collector_state()->set_gcs_are_young(true);
1260
1261 // See the comments in g1CollectedHeap.hpp and
1262 // G1CollectedHeap::ref_processing_init() about
1263 // how reference processing currently works in G1.
1264
1265 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1266 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1267
1268 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1269 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1270
1271 ref_processor_stw()->enable_discovery();
1272 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1273
1274 // Do collection work
1275 {
1276 HandleMark hm; // Discard invalid handles created during gc
1277 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1278 }
1279
1280 assert(num_free_regions() == 0, "we should not have added any free regions");
1281 rebuild_region_sets(false /* free_list_only */);
1282
1283 // Enqueue any discovered reference objects that have
1284 // not been removed from the discovered lists.
1285 ref_processor_stw()->enqueue_discovered_references();
1286
1287 #if defined(COMPILER2) || INCLUDE_JVMCI
1288 DerivedPointerTable::update_pointers();
1289 #endif
1290
1291 MemoryService::track_memory_usage();
1292
1293 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1294 ref_processor_stw()->verify_no_references_recorded();
1295
1296 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1297 ClassLoaderDataGraph::purge();
1298 MetaspaceAux::verify_metrics();
1299
1300 // Note: since we've just done a full GC, concurrent
1301 // marking is no longer active. Therefore we need not
1302 // re-enable reference discovery for the CM ref processor.
1303 // That will be done at the start of the next marking cycle.
1304 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1305 ref_processor_cm()->verify_no_references_recorded();
1306
1307 reset_gc_time_stamp();
1308 // Since everything potentially moved, we will clear all remembered
1309 // sets, and clear all cards. Later we will rebuild remembered
1310 // sets. We will also reset the GC time stamps of the regions.
1311 clear_rsets_post_compaction();
1312 check_gc_time_stamps();
1313
1314 resize_if_necessary_after_full_collection();
1315
1316 // We should do this after we potentially resize the heap so
1317 // that all the COMMIT / UNCOMMIT events are generated before
1318 // the compaction events.
1319 print_hrm_post_compaction();
1320
1321 if (_hot_card_cache->use_cache()) {
1322 _hot_card_cache->reset_card_counts();
1323 _hot_card_cache->reset_hot_cache();
1324 }
1325
1326 // Rebuild remembered sets of all regions.
1327 uint n_workers =
1328 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1329 workers()->active_workers(),
1330 Threads::number_of_non_daemon_threads());
1331 workers()->update_active_workers(n_workers);
1332 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1333
1334 ParRebuildRSTask rebuild_rs_task(this);
1335 workers()->run_task(&rebuild_rs_task);
1336
1337 // Rebuild the strong code root lists for each region
1338 rebuild_strong_code_roots();
1339
1340 if (true) { // FIXME
1341 MetaspaceGC::compute_new_size();
1342 }
1343
1344 #ifdef TRACESPINNING
1345 ParallelTaskTerminator::print_termination_counts();
1346 #endif
1347
1348 // Discard all rset updates
1349 JavaThread::dirty_card_queue_set().abandon_logs();
1350 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1351
1352 // At this point there should be no regions in the
1353 // entire heap tagged as young.
1354 assert(check_young_list_empty(), "young list should be empty at this point");
1355
1356 // Update the number of full collections that have been completed.
1357 increment_old_marking_cycles_completed(false /* concurrent */);
1358
1359 _hrm.verify_optional();
1360 _verifier->verify_region_sets_optional();
1361
1362 _verifier->verify_after_gc();
1363
1364 // Clear the previous marking bitmap, if needed for bitmap verification.
1365 // Note we cannot do this when we clear the next marking bitmap in
1366 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1367 // objects marked during a full GC against the previous bitmap.
1368 // But we need to clear it before calling check_bitmaps below since
1369 // the full GC has compacted objects and updated TAMS but not updated
1370 // the prev bitmap.
1371 if (G1VerifyBitmaps) {
1372 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1373 _cm->clear_prev_bitmap(workers());
1374 }
1375 _verifier->check_bitmaps("Full GC End");
1376
1377 start_new_collection_set();
1378
1379 _allocator->init_mutator_alloc_region();
1380
1381 g1_policy()->record_full_collection_end();
1382
1383 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1384 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1385 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1386 // before any GC notifications are raised.
1387 g1mm()->update_sizes();
1388
1389 gc_epilogue(true);
1390
1391 heap_transition.print();
1392
1393 print_heap_after_gc();
1394 print_heap_regions();
1395 trace_heap_after_gc(gc_tracer);
1396
1397 post_full_gc_dump(gc_timer);
1398 }
1399
1400 gc_timer->register_gc_end();
1401 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1402 }
1403
1404 return true;
1405 }
1406
1407 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1408 // Currently, there is no facility in the do_full_collection(bool) API to notify
1409 // the caller that the collection did not succeed (e.g., because it was locked
1410 // out by the GC locker). So, right now, we'll ignore the return value.
1411 bool dummy = do_full_collection(true, /* explicit_gc */
1412 clear_all_soft_refs);
1413 }
1414
1415 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1416 // Include bytes that will be pre-allocated to support collections, as "used".
1417 const size_t used_after_gc = used();
1418 const size_t capacity_after_gc = capacity();
1419 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1420
1421 // This is enforced in arguments.cpp.
1422 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1423 "otherwise the code below doesn't make sense");
1424
1425 // We don't have floating point command-line arguments
1426 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1427 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1428 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1429 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1430
1431 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1432 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1433
1434 // We have to be careful here as these two calculations can overflow
1435 // 32-bit size_t's.
1436 double used_after_gc_d = (double) used_after_gc;
1437 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1438 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1439
1440 // Let's make sure that they are both under the max heap size, which
1441 // by default will make them fit into a size_t.
1442 double desired_capacity_upper_bound = (double) max_heap_size;
1443 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1444 desired_capacity_upper_bound);
1445 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1446 desired_capacity_upper_bound);
1447
1448 // We can now safely turn them into size_t's.
1449 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1450 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1451
1452 // This assert only makes sense here, before we adjust them
1453 // with respect to the min and max heap size.
1454 assert(minimum_desired_capacity <= maximum_desired_capacity,
1455 "minimum_desired_capacity = " SIZE_FORMAT ", "
1456 "maximum_desired_capacity = " SIZE_FORMAT,
1457 minimum_desired_capacity, maximum_desired_capacity);
1458
1459 // Should not be greater than the heap max size. No need to adjust
1460 // it with respect to the heap min size as it's a lower bound (i.e.,
1461 // we'll try to make the capacity larger than it, not smaller).
1462 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1463 // Should not be less than the heap min size. No need to adjust it
1464 // with respect to the heap max size as it's an upper bound (i.e.,
1465 // we'll try to make the capacity smaller than it, not greater).
1466 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1467
1468 if (capacity_after_gc < minimum_desired_capacity) {
1469 // Don't expand unless it's significant
1470 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1471
1472 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1473 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1474 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1475
1476 expand(expand_bytes, _workers);
1477
1478 // No expansion, now see if we want to shrink
1479 } else if (capacity_after_gc > maximum_desired_capacity) {
1480 // Capacity too large, compute shrinking size
1481 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1482
1483 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1484 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1485 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1486
1487 shrink(shrink_bytes);
1488 }
1489 }
1490
1491 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1492 AllocationContext_t context,
1493 bool do_gc,
1494 bool clear_all_soft_refs,
1495 bool expect_null_mutator_alloc_region,
1496 bool* gc_succeeded) {
1497 *gc_succeeded = true;
1498 // Let's attempt the allocation first.
1499 HeapWord* result =
1500 attempt_allocation_at_safepoint(word_size,
1501 context,
1502 expect_null_mutator_alloc_region);
1503 if (result != NULL) {
1504 assert(*gc_succeeded, "sanity");
1505 return result;
1506 }
1507
1508 // In a G1 heap, we're supposed to keep allocation from failing by
1509 // incremental pauses. Therefore, at least for now, we'll favor
1510 // expansion over collection. (This might change in the future if we can
1511 // do something smarter than full collection to satisfy a failed alloc.)
1512 result = expand_and_allocate(word_size, context);
1513 if (result != NULL) {
1514 assert(*gc_succeeded, "sanity");
1515 return result;
1516 }
1517
1518 if (do_gc) {
1519 // Expansion didn't work, we'll try to do a Full GC.
1520 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1521 clear_all_soft_refs);
1522 }
1523
1524 return NULL;
1525 }
1526
1527 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1528 AllocationContext_t context,
1529 bool* succeeded) {
1530 assert_at_safepoint(true /* should_be_vm_thread */);
1531
1532 // Attempts to allocate followed by Full GC.
1533 HeapWord* result =
1534 satisfy_failed_allocation_helper(word_size,
1535 context,
1536 true, /* do_gc */
1537 false, /* clear_all_soft_refs */
1538 false, /* expect_null_mutator_alloc_region */
1539 succeeded);
1540
1541 if (result != NULL || !*succeeded) {
1542 return result;
1543 }
1544
1545 // Attempts to allocate followed by Full GC that will collect all soft references.
1546 result = satisfy_failed_allocation_helper(word_size,
1547 context,
1548 true, /* do_gc */
1549 true, /* clear_all_soft_refs */
1550 true, /* expect_null_mutator_alloc_region */
1551 succeeded);
1552
1553 if (result != NULL || !*succeeded) {
1554 return result;
1555 }
1556
1557 // Attempts to allocate, no GC
1558 result = satisfy_failed_allocation_helper(word_size,
1559 context,
1560 false, /* do_gc */
1561 false, /* clear_all_soft_refs */
1562 true, /* expect_null_mutator_alloc_region */
1563 succeeded);
1564
1565 if (result != NULL) {
1566 assert(*succeeded, "sanity");
1567 return result;
1568 }
1569
1570 assert(!collector_policy()->should_clear_all_soft_refs(),
1571 "Flag should have been handled and cleared prior to this point");
1572
1573 // What else? We might try synchronous finalization later. If the total
1574 // space available is large enough for the allocation, then a more
1575 // complete compaction phase than we've tried so far might be
1576 // appropriate.
1577 assert(*succeeded, "sanity");
1578 return NULL;
1579 }
1580
1581 // Attempting to expand the heap sufficiently
1582 // to support an allocation of the given "word_size". If
1583 // successful, perform the allocation and return the address of the
1584 // allocated block, or else "NULL".
1585
1586 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1587 assert_at_safepoint(true /* should_be_vm_thread */);
1588
1589 _verifier->verify_region_sets_optional();
1590
1591 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1592 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1593 word_size * HeapWordSize);
1594
1595
1596 if (expand(expand_bytes, _workers)) {
1597 _hrm.verify_optional();
1598 _verifier->verify_region_sets_optional();
1599 return attempt_allocation_at_safepoint(word_size,
1600 context,
1601 false /* expect_null_mutator_alloc_region */);
1602 }
1603 return NULL;
1604 }
1605
1606 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1607 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1608 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1609 HeapRegion::GrainBytes);
1610
1611 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1612 expand_bytes, aligned_expand_bytes);
1613
1614 if (is_maximal_no_gc()) {
1615 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1616 return false;
1617 }
1618
1619 double expand_heap_start_time_sec = os::elapsedTime();
1620 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1621 assert(regions_to_expand > 0, "Must expand by at least one region");
1622
1623 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1624 if (expand_time_ms != NULL) {
1625 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1626 }
1627
1628 if (expanded_by > 0) {
1629 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1630 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1631 g1_policy()->record_new_heap_size(num_regions());
1632 } else {
1633 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1634
1635 // The expansion of the virtual storage space was unsuccessful.
1636 // Let's see if it was because we ran out of swap.
1637 if (G1ExitOnExpansionFailure &&
1638 _hrm.available() >= regions_to_expand) {
1639 // We had head room...
1640 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1641 }
1642 }
1643 return regions_to_expand > 0;
1644 }
1645
1646 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1647 size_t aligned_shrink_bytes =
1648 ReservedSpace::page_align_size_down(shrink_bytes);
1649 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1650 HeapRegion::GrainBytes);
1651 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1652
1653 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1654 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1655
1656
1657 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1658 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1659 if (num_regions_removed > 0) {
1660 g1_policy()->record_new_heap_size(num_regions());
1661 } else {
1662 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1663 }
1664 }
1665
1666 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1667 _verifier->verify_region_sets_optional();
1668
1669 // We should only reach here at the end of a Full GC which means we
1670 // should not not be holding to any GC alloc regions. The method
1671 // below will make sure of that and do any remaining clean up.
1672 _allocator->abandon_gc_alloc_regions();
1673
1674 // Instead of tearing down / rebuilding the free lists here, we
1675 // could instead use the remove_all_pending() method on free_list to
1676 // remove only the ones that we need to remove.
1677 tear_down_region_sets(true /* free_list_only */);
1678 shrink_helper(shrink_bytes);
1679 rebuild_region_sets(true /* free_list_only */);
1680
1681 _hrm.verify_optional();
1682 _verifier->verify_region_sets_optional();
1683 }
1684
1685 // Public methods.
1686
1687 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1688 CollectedHeap(),
1689 _collector_policy(collector_policy),
1690 _g1_policy(create_g1_policy()),
1691 _collection_set(this, _g1_policy),
1692 _dirty_card_queue_set(false),
1693 _is_alive_closure_cm(this),
1694 _is_alive_closure_stw(this),
1695 _ref_processor_cm(NULL),
1696 _ref_processor_stw(NULL),
1697 _bot(NULL),
1698 _hot_card_cache(NULL),
1699 _g1_rem_set(NULL),
1700 _cg1r(NULL),
1701 _g1mm(NULL),
1702 _refine_cte_cl(NULL),
1703 _preserved_marks_set(true /* in_c_heap */),
1704 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1705 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1706 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1707 _humongous_reclaim_candidates(),
1708 _has_humongous_reclaim_candidates(false),
1709 _archive_allocator(NULL),
1710 _free_regions_coming(false),
1711 _gc_time_stamp(0),
1712 _summary_bytes_used(0),
1713 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1714 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1715 _expand_heap_after_alloc_failure(true),
1716 _old_marking_cycles_started(0),
1717 _old_marking_cycles_completed(0),
1718 _in_cset_fast_test(),
1719 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1720 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1721
1722 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1723 /* are_GC_task_threads */true,
1724 /* are_ConcurrentGC_threads */false);
1725 _workers->initialize_workers();
1726 _verifier = new G1HeapVerifier(this);
1727
1728 _allocator = G1Allocator::create_allocator(this);
1729
1730 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1731
1732 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1733
1734 // Override the default _filler_array_max_size so that no humongous filler
1735 // objects are created.
1736 _filler_array_max_size = _humongous_object_threshold_in_words;
1737
1738 uint n_queues = ParallelGCThreads;
1739 _task_queues = new RefToScanQueueSet(n_queues);
1740
1741 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1742
1743 for (uint i = 0; i < n_queues; i++) {
1744 RefToScanQueue* q = new RefToScanQueue();
1745 q->initialize();
1746 _task_queues->register_queue(i, q);
1747 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1748 }
1749
1750 // Initialize the G1EvacuationFailureALot counters and flags.
1751 NOT_PRODUCT(reset_evacuation_should_fail();)
1752
1753 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1754 }
1755
1756 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1757 size_t size,
1758 size_t translation_factor) {
1759 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1760 // Allocate a new reserved space, preferring to use large pages.
1761 ReservedSpace rs(size, preferred_page_size);
1762 G1RegionToSpaceMapper* result =
1763 G1RegionToSpaceMapper::create_mapper(rs,
1764 size,
1765 rs.alignment(),
1766 HeapRegion::GrainBytes,
1767 translation_factor,
1768 mtGC);
1769
1770 os::trace_page_sizes_for_requested_size(description,
1771 size,
1772 preferred_page_size,
1773 rs.alignment(),
1774 rs.base(),
1775 rs.size());
1776
1777 return result;
1778 }
1779
1780 jint G1CollectedHeap::initialize() {
1781 CollectedHeap::pre_initialize();
1782 os::enable_vtime();
1783
1784 // Necessary to satisfy locking discipline assertions.
1785
1786 MutexLocker x(Heap_lock);
1787
1788 // While there are no constraints in the GC code that HeapWordSize
1789 // be any particular value, there are multiple other areas in the
1790 // system which believe this to be true (e.g. oop->object_size in some
1791 // cases incorrectly returns the size in wordSize units rather than
1792 // HeapWordSize).
1793 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1794
1795 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1796 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1797 size_t heap_alignment = collector_policy()->heap_alignment();
1798
1799 // Ensure that the sizes are properly aligned.
1800 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1801 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1802 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1803
1804 _refine_cte_cl = new RefineCardTableEntryClosure();
1805
1806 jint ecode = JNI_OK;
1807 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1808 if (_cg1r == NULL) {
1809 return ecode;
1810 }
1811
1812 // Reserve the maximum.
1813
1814 // When compressed oops are enabled, the preferred heap base
1815 // is calculated by subtracting the requested size from the
1816 // 32Gb boundary and using the result as the base address for
1817 // heap reservation. If the requested size is not aligned to
1818 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1819 // into the ReservedHeapSpace constructor) then the actual
1820 // base of the reserved heap may end up differing from the
1821 // address that was requested (i.e. the preferred heap base).
1822 // If this happens then we could end up using a non-optimal
1823 // compressed oops mode.
1824
1825 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1826 heap_alignment);
1827
1828 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1829
1830 // Create the barrier set for the entire reserved region.
1831 G1SATBCardTableLoggingModRefBS* bs
1832 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1833 bs->initialize();
1834 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1835 set_barrier_set(bs);
1836
1837 // Create the hot card cache.
1838 _hot_card_cache = new G1HotCardCache(this);
1839
1840 // Also create a G1 rem set.
1841 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1842
1843 // Carve out the G1 part of the heap.
1844 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1845 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1846 G1RegionToSpaceMapper* heap_storage =
1847 G1RegionToSpaceMapper::create_mapper(g1_rs,
1848 g1_rs.size(),
1849 page_size,
1850 HeapRegion::GrainBytes,
1851 1,
1852 mtJavaHeap);
1853 os::trace_page_sizes("Heap",
1854 collector_policy()->min_heap_byte_size(),
1855 max_byte_size,
1856 page_size,
1857 heap_rs.base(),
1858 heap_rs.size());
1859 heap_storage->set_mapping_changed_listener(&_listener);
1860
1861 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1862 G1RegionToSpaceMapper* bot_storage =
1863 create_aux_memory_mapper("Block Offset Table",
1864 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1865 G1BlockOffsetTable::heap_map_factor());
1866
1867 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1868 G1RegionToSpaceMapper* cardtable_storage =
1869 create_aux_memory_mapper("Card Table",
1870 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1871 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1872
1873 G1RegionToSpaceMapper* card_counts_storage =
1874 create_aux_memory_mapper("Card Counts Table",
1875 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1876 G1CardCounts::heap_map_factor());
1877
1878 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1879 G1RegionToSpaceMapper* prev_bitmap_storage =
1880 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1881 G1RegionToSpaceMapper* next_bitmap_storage =
1882 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1883
1884 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1885 g1_barrier_set()->initialize(cardtable_storage);
1886 // Do later initialization work for concurrent refinement.
1887 _hot_card_cache->initialize(card_counts_storage);
1888
1889 // 6843694 - ensure that the maximum region index can fit
1890 // in the remembered set structures.
1891 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1892 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1893
1894 g1_rem_set()->initialize(max_capacity(), max_regions());
1895
1896 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1897 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1898 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1899 "too many cards per region");
1900
1901 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1902
1903 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1904
1905 {
1906 HeapWord* start = _hrm.reserved().start();
1907 HeapWord* end = _hrm.reserved().end();
1908 size_t granularity = HeapRegion::GrainBytes;
1909
1910 _in_cset_fast_test.initialize(start, end, granularity);
1911 _humongous_reclaim_candidates.initialize(start, end, granularity);
1912 }
1913
1914 // Create the G1ConcurrentMark data structure and thread.
1915 // (Must do this late, so that "max_regions" is defined.)
1916 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1917 if (_cm == NULL || !_cm->completed_initialization()) {
1918 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1919 return JNI_ENOMEM;
1920 }
1921 _cmThread = _cm->cmThread();
1922
1923 // Now expand into the initial heap size.
1924 if (!expand(init_byte_size, _workers)) {
1925 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1926 return JNI_ENOMEM;
1927 }
1928
1929 // Perform any initialization actions delegated to the policy.
1930 g1_policy()->init(this, &_collection_set);
1931
1932 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1933 SATB_Q_FL_lock,
1934 G1SATBProcessCompletedThreshold,
1935 Shared_SATB_Q_lock);
1936
1937 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1938 DirtyCardQ_CBL_mon,
1939 DirtyCardQ_FL_lock,
1940 (int)concurrent_g1_refine()->yellow_zone(),
1941 (int)concurrent_g1_refine()->red_zone(),
1942 Shared_DirtyCardQ_lock,
1943 NULL, // fl_owner
1944 true); // init_free_ids
1945
1946 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1947 DirtyCardQ_CBL_mon,
1948 DirtyCardQ_FL_lock,
1949 -1, // never trigger processing
1950 -1, // no limit on length
1951 Shared_DirtyCardQ_lock,
1952 &JavaThread::dirty_card_queue_set());
1953
1954 // Here we allocate the dummy HeapRegion that is required by the
1955 // G1AllocRegion class.
1956 HeapRegion* dummy_region = _hrm.get_dummy_region();
1957
1958 // We'll re-use the same region whether the alloc region will
1959 // require BOT updates or not and, if it doesn't, then a non-young
1960 // region will complain that it cannot support allocations without
1961 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1962 dummy_region->set_eden();
1963 // Make sure it's full.
1964 dummy_region->set_top(dummy_region->end());
1965 G1AllocRegion::setup(this, dummy_region);
1966
1967 _allocator->init_mutator_alloc_region();
1968
1969 // Do create of the monitoring and management support so that
1970 // values in the heap have been properly initialized.
1971 _g1mm = new G1MonitoringSupport(this);
1972
1973 G1StringDedup::initialize();
1974
1975 _preserved_marks_set.init(ParallelGCThreads);
1976
1977 _collection_set.initialize(max_regions());
1978
1979 return JNI_OK;
1980 }
1981
1982 void G1CollectedHeap::stop() {
1983 // Stop all concurrent threads. We do this to make sure these threads
1984 // do not continue to execute and access resources (e.g. logging)
1985 // that are destroyed during shutdown.
1986 _cg1r->stop();
1987 _cmThread->stop();
1988 if (G1StringDedup::is_enabled()) {
1989 G1StringDedup::stop();
1990 }
1991 }
1992
1993 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1994 return HeapRegion::max_region_size();
1995 }
1996
1997 void G1CollectedHeap::post_initialize() {
1998 ref_processing_init();
1999 }
2000
2001 void G1CollectedHeap::ref_processing_init() {
2002 // Reference processing in G1 currently works as follows:
2003 //
2004 // * There are two reference processor instances. One is
2005 // used to record and process discovered references
2006 // during concurrent marking; the other is used to
2007 // record and process references during STW pauses
2008 // (both full and incremental).
2009 // * Both ref processors need to 'span' the entire heap as
2010 // the regions in the collection set may be dotted around.
2011 //
2012 // * For the concurrent marking ref processor:
2013 // * Reference discovery is enabled at initial marking.
2014 // * Reference discovery is disabled and the discovered
2015 // references processed etc during remarking.
2016 // * Reference discovery is MT (see below).
2017 // * Reference discovery requires a barrier (see below).
2018 // * Reference processing may or may not be MT
2019 // (depending on the value of ParallelRefProcEnabled
2020 // and ParallelGCThreads).
2021 // * A full GC disables reference discovery by the CM
2022 // ref processor and abandons any entries on it's
2023 // discovered lists.
2024 //
2025 // * For the STW processor:
2026 // * Non MT discovery is enabled at the start of a full GC.
2027 // * Processing and enqueueing during a full GC is non-MT.
2028 // * During a full GC, references are processed after marking.
2029 //
2030 // * Discovery (may or may not be MT) is enabled at the start
2031 // of an incremental evacuation pause.
2032 // * References are processed near the end of a STW evacuation pause.
2033 // * For both types of GC:
2034 // * Discovery is atomic - i.e. not concurrent.
2035 // * Reference discovery will not need a barrier.
2036
2037 MemRegion mr = reserved_region();
2038
2039 // Concurrent Mark ref processor
2040 _ref_processor_cm =
2041 new ReferenceProcessor(mr, // span
2042 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2043 // mt processing
2044 ParallelGCThreads,
2045 // degree of mt processing
2046 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2047 // mt discovery
2048 MAX2(ParallelGCThreads, ConcGCThreads),
2049 // degree of mt discovery
2050 false,
2051 // Reference discovery is not atomic
2052 &_is_alive_closure_cm);
2053 // is alive closure
2054 // (for efficiency/performance)
2055
2056 // STW ref processor
2057 _ref_processor_stw =
2058 new ReferenceProcessor(mr, // span
2059 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2060 // mt processing
2061 ParallelGCThreads,
2062 // degree of mt processing
2063 (ParallelGCThreads > 1),
2064 // mt discovery
2065 ParallelGCThreads,
2066 // degree of mt discovery
2067 true,
2068 // Reference discovery is atomic
2069 &_is_alive_closure_stw);
2070 // is alive closure
2071 // (for efficiency/performance)
2072 }
2073
2074 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2075 return _collector_policy;
2076 }
2077
2078 size_t G1CollectedHeap::capacity() const {
2079 return _hrm.length() * HeapRegion::GrainBytes;
2080 }
2081
2082 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2083 hr->reset_gc_time_stamp();
2084 }
2085
2086 #ifndef PRODUCT
2087
2088 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2089 private:
2090 unsigned _gc_time_stamp;
2091 bool _failures;
2092
2093 public:
2094 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2095 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2096
2097 virtual bool doHeapRegion(HeapRegion* hr) {
2098 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2099 if (_gc_time_stamp != region_gc_time_stamp) {
2100 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2101 region_gc_time_stamp, _gc_time_stamp);
2102 _failures = true;
2103 }
2104 return false;
2105 }
2106
2107 bool failures() { return _failures; }
2108 };
2109
2110 void G1CollectedHeap::check_gc_time_stamps() {
2111 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2112 heap_region_iterate(&cl);
2113 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2114 }
2115 #endif // PRODUCT
2116
2117 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2118 _hot_card_cache->drain(cl, worker_i);
2119 }
2120
2121 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2122 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2123 size_t n_completed_buffers = 0;
2124 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2125 n_completed_buffers++;
2126 }
2127 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2128 dcqs.clear_n_completed_buffers();
2129 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2130 }
2131
2132 // Computes the sum of the storage used by the various regions.
2133 size_t G1CollectedHeap::used() const {
2134 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2135 if (_archive_allocator != NULL) {
2136 result += _archive_allocator->used();
2137 }
2138 return result;
2139 }
2140
2141 size_t G1CollectedHeap::used_unlocked() const {
2142 return _summary_bytes_used;
2143 }
2144
2145 class SumUsedClosure: public HeapRegionClosure {
2146 size_t _used;
2147 public:
2148 SumUsedClosure() : _used(0) {}
2149 bool doHeapRegion(HeapRegion* r) {
2150 _used += r->used();
2151 return false;
2152 }
2153 size_t result() { return _used; }
2154 };
2155
2156 size_t G1CollectedHeap::recalculate_used() const {
2157 double recalculate_used_start = os::elapsedTime();
2158
2159 SumUsedClosure blk;
2160 heap_region_iterate(&blk);
2161
2162 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2163 return blk.result();
2164 }
2165
2166 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2167 switch (cause) {
2168 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2169 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2170 case GCCause::_update_allocation_context_stats_inc: return true;
2171 case GCCause::_wb_conc_mark: return true;
2172 default : return false;
2173 }
2174 }
2175
2176 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2177 switch (cause) {
2178 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2179 case GCCause::_g1_humongous_allocation: return true;
2180 default: return is_user_requested_concurrent_full_gc(cause);
2181 }
2182 }
2183
2184 #ifndef PRODUCT
2185 void G1CollectedHeap::allocate_dummy_regions() {
2186 // Let's fill up most of the region
2187 size_t word_size = HeapRegion::GrainWords - 1024;
2188 // And as a result the region we'll allocate will be humongous.
2189 guarantee(is_humongous(word_size), "sanity");
2190
2191 // _filler_array_max_size is set to humongous object threshold
2192 // but temporarily change it to use CollectedHeap::fill_with_object().
2193 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2194
2195 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2196 // Let's use the existing mechanism for the allocation
2197 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2198 AllocationContext::system());
2199 if (dummy_obj != NULL) {
2200 MemRegion mr(dummy_obj, word_size);
2201 CollectedHeap::fill_with_object(mr);
2202 } else {
2203 // If we can't allocate once, we probably cannot allocate
2204 // again. Let's get out of the loop.
2205 break;
2206 }
2207 }
2208 }
2209 #endif // !PRODUCT
2210
2211 void G1CollectedHeap::increment_old_marking_cycles_started() {
2212 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2213 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2214 "Wrong marking cycle count (started: %d, completed: %d)",
2215 _old_marking_cycles_started, _old_marking_cycles_completed);
2216
2217 _old_marking_cycles_started++;
2218 }
2219
2220 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2221 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2222
2223 // We assume that if concurrent == true, then the caller is a
2224 // concurrent thread that was joined the Suspendible Thread
2225 // Set. If there's ever a cheap way to check this, we should add an
2226 // assert here.
2227
2228 // Given that this method is called at the end of a Full GC or of a
2229 // concurrent cycle, and those can be nested (i.e., a Full GC can
2230 // interrupt a concurrent cycle), the number of full collections
2231 // completed should be either one (in the case where there was no
2232 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2233 // behind the number of full collections started.
2234
2235 // This is the case for the inner caller, i.e. a Full GC.
2236 assert(concurrent ||
2237 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2238 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2239 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2240 "is inconsistent with _old_marking_cycles_completed = %u",
2241 _old_marking_cycles_started, _old_marking_cycles_completed);
2242
2243 // This is the case for the outer caller, i.e. the concurrent cycle.
2244 assert(!concurrent ||
2245 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2246 "for outer caller (concurrent cycle): "
2247 "_old_marking_cycles_started = %u "
2248 "is inconsistent with _old_marking_cycles_completed = %u",
2249 _old_marking_cycles_started, _old_marking_cycles_completed);
2250
2251 _old_marking_cycles_completed += 1;
2252
2253 // We need to clear the "in_progress" flag in the CM thread before
2254 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2255 // is set) so that if a waiter requests another System.gc() it doesn't
2256 // incorrectly see that a marking cycle is still in progress.
2257 if (concurrent) {
2258 _cmThread->set_idle();
2259 }
2260
2261 // This notify_all() will ensure that a thread that called
2262 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2263 // and it's waiting for a full GC to finish will be woken up. It is
2264 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2265 FullGCCount_lock->notify_all();
2266 }
2267
2268 void G1CollectedHeap::collect(GCCause::Cause cause) {
2269 assert_heap_not_locked();
2270
2271 uint gc_count_before;
2272 uint old_marking_count_before;
2273 uint full_gc_count_before;
2274 bool retry_gc;
2275
2276 do {
2277 retry_gc = false;
2278
2279 {
2280 MutexLocker ml(Heap_lock);
2281
2282 // Read the GC count while holding the Heap_lock
2283 gc_count_before = total_collections();
2284 full_gc_count_before = total_full_collections();
2285 old_marking_count_before = _old_marking_cycles_started;
2286 }
2287
2288 if (should_do_concurrent_full_gc(cause)) {
2289 // Schedule an initial-mark evacuation pause that will start a
2290 // concurrent cycle. We're setting word_size to 0 which means that
2291 // we are not requesting a post-GC allocation.
2292 VM_G1IncCollectionPause op(gc_count_before,
2293 0, /* word_size */
2294 true, /* should_initiate_conc_mark */
2295 g1_policy()->max_pause_time_ms(),
2296 cause);
2297 op.set_allocation_context(AllocationContext::current());
2298
2299 VMThread::execute(&op);
2300 if (!op.pause_succeeded()) {
2301 if (old_marking_count_before == _old_marking_cycles_started) {
2302 retry_gc = op.should_retry_gc();
2303 } else {
2304 // A Full GC happened while we were trying to schedule the
2305 // initial-mark GC. No point in starting a new cycle given
2306 // that the whole heap was collected anyway.
2307 }
2308
2309 if (retry_gc) {
2310 if (GCLocker::is_active_and_needs_gc()) {
2311 GCLocker::stall_until_clear();
2312 }
2313 }
2314 }
2315 } else {
2316 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2317 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2318
2319 // Schedule a standard evacuation pause. We're setting word_size
2320 // to 0 which means that we are not requesting a post-GC allocation.
2321 VM_G1IncCollectionPause op(gc_count_before,
2322 0, /* word_size */
2323 false, /* should_initiate_conc_mark */
2324 g1_policy()->max_pause_time_ms(),
2325 cause);
2326 VMThread::execute(&op);
2327 } else {
2328 // Schedule a Full GC.
2329 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2330 VMThread::execute(&op);
2331 }
2332 }
2333 } while (retry_gc);
2334 }
2335
2336 bool G1CollectedHeap::is_in(const void* p) const {
2337 if (_hrm.reserved().contains(p)) {
2338 // Given that we know that p is in the reserved space,
2339 // heap_region_containing() should successfully
2340 // return the containing region.
2341 HeapRegion* hr = heap_region_containing(p);
2342 return hr->is_in(p);
2343 } else {
2344 return false;
2345 }
2346 }
2347
2348 #ifdef ASSERT
2349 bool G1CollectedHeap::is_in_exact(const void* p) const {
2350 bool contains = reserved_region().contains(p);
2351 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2352 if (contains && available) {
2353 return true;
2354 } else {
2355 return false;
2356 }
2357 }
2358 #endif
2359
2360 // Iteration functions.
2361
2362 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2363
2364 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2365 ExtendedOopClosure* _cl;
2366 public:
2367 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2368 bool doHeapRegion(HeapRegion* r) {
2369 if (!r->is_continues_humongous()) {
2370 r->oop_iterate(_cl);
2371 }
2372 return false;
2373 }
2374 };
2375
2376 // Iterates an ObjectClosure over all objects within a HeapRegion.
2377
2378 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2379 ObjectClosure* _cl;
2380 public:
2381 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2382 bool doHeapRegion(HeapRegion* r) {
2383 if (!r->is_continues_humongous()) {
2384 r->object_iterate(_cl);
2385 }
2386 return false;
2387 }
2388 };
2389
2390 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2391 IterateObjectClosureRegionClosure blk(cl);
2392 heap_region_iterate(&blk);
2393 }
2394
2395 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2396 _hrm.iterate(cl);
2397 }
2398
2399 void
2400 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2401 uint worker_id,
2402 HeapRegionClaimer *hrclaimer,
2403 bool concurrent) const {
2404 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2405 }
2406
2407 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2408 _collection_set.iterate(cl);
2409 }
2410
2411 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2412 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2413 }
2414
2415 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2416 HeapRegion* result = _hrm.next_region_in_heap(from);
2417 while (result != NULL && result->is_pinned()) {
2418 result = _hrm.next_region_in_heap(result);
2419 }
2420 return result;
2421 }
2422
2423 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2424 HeapRegion* hr = heap_region_containing(addr);
2425 return hr->block_start(addr);
2426 }
2427
2428 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2429 HeapRegion* hr = heap_region_containing(addr);
2430 return hr->block_size(addr);
2431 }
2432
2433 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2434 HeapRegion* hr = heap_region_containing(addr);
2435 return hr->block_is_obj(addr);
2436 }
2437
2438 bool G1CollectedHeap::supports_tlab_allocation() const {
2439 return true;
2440 }
2441
2442 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2443 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2444 }
2445
2446 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2447 return _eden.length() * HeapRegion::GrainBytes;
2448 }
2449
2450 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2451 // must be equal to the humongous object limit.
2452 size_t G1CollectedHeap::max_tlab_size() const {
2453 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2454 }
2455
2456 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2457 AllocationContext_t context = AllocationContext::current();
2458 return _allocator->unsafe_max_tlab_alloc(context);
2459 }
2460
2461 size_t G1CollectedHeap::max_capacity() const {
2462 return _hrm.reserved().byte_size();
2463 }
2464
2465 jlong G1CollectedHeap::millis_since_last_gc() {
2466 // See the notes in GenCollectedHeap::millis_since_last_gc()
2467 // for more information about the implementation.
2468 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2469 _g1_policy->collection_pause_end_millis();
2470 if (ret_val < 0) {
2471 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2472 ". returning zero instead.", ret_val);
2473 return 0;
2474 }
2475 return ret_val;
2476 }
2477
2478 void G1CollectedHeap::prepare_for_verify() {
2479 _verifier->prepare_for_verify();
2480 }
2481
2482 void G1CollectedHeap::verify(VerifyOption vo) {
2483 _verifier->verify(vo);
2484 }
2485
2486 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2487 return true;
2488 }
2489
2490 const char* const* G1CollectedHeap::concurrent_phases() const {
2491 return _cmThread->concurrent_phases();
2492 }
2493
2494 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2495 return _cmThread->request_concurrent_phase(phase);
2496 }
2497
2498 class PrintRegionClosure: public HeapRegionClosure {
2499 outputStream* _st;
2500 public:
2501 PrintRegionClosure(outputStream* st) : _st(st) {}
2502 bool doHeapRegion(HeapRegion* r) {
2503 r->print_on(_st);
2504 return false;
2505 }
2506 };
2507
2508 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2509 const HeapRegion* hr,
2510 const VerifyOption vo) const {
2511 switch (vo) {
2512 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2513 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2514 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2515 default: ShouldNotReachHere();
2516 }
2517 return false; // keep some compilers happy
2518 }
2519
2520 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2521 const VerifyOption vo) const {
2522 switch (vo) {
2523 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2524 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2525 case VerifyOption_G1UseMarkWord: {
2526 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2527 return !obj->is_gc_marked() && !hr->is_archive();
2528 }
2529 default: ShouldNotReachHere();
2530 }
2531 return false; // keep some compilers happy
2532 }
2533
2534 void G1CollectedHeap::print_heap_regions() const {
2535 Log(gc, heap, region) log;
2536 if (log.is_trace()) {
2537 ResourceMark rm;
2538 print_regions_on(log.trace_stream());
2539 }
2540 }
2541
2542 void G1CollectedHeap::print_on(outputStream* st) const {
2543 st->print(" %-20s", "garbage-first heap");
2544 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2545 capacity()/K, used_unlocked()/K);
2546 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2547 p2i(_hrm.reserved().start()),
2548 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2549 p2i(_hrm.reserved().end()));
2550 st->cr();
2551 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2552 uint young_regions = young_regions_count();
2553 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2554 (size_t) young_regions * HeapRegion::GrainBytes / K);
2555 uint survivor_regions = survivor_regions_count();
2556 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2557 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2558 st->cr();
2559 MetaspaceAux::print_on(st);
2560 }
2561
2562 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2563 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2564 "HS=humongous(starts), HC=humongous(continues), "
2565 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2566 "AC=allocation context, "
2567 "TAMS=top-at-mark-start (previous, next)");
2568 PrintRegionClosure blk(st);
2569 heap_region_iterate(&blk);
2570 }
2571
2572 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2573 print_on(st);
2574
2575 // Print the per-region information.
2576 print_regions_on(st);
2577 }
2578
2579 void G1CollectedHeap::print_on_error(outputStream* st) const {
2580 this->CollectedHeap::print_on_error(st);
2581
2582 if (_cm != NULL) {
2583 st->cr();
2584 _cm->print_on_error(st);
2585 }
2586 }
2587
2588 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2589 workers()->print_worker_threads_on(st);
2590 _cmThread->print_on(st);
2591 st->cr();
2592 _cm->print_worker_threads_on(st);
2593 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2594 if (G1StringDedup::is_enabled()) {
2595 G1StringDedup::print_worker_threads_on(st);
2596 }
2597 }
2598
2599 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2600 workers()->threads_do(tc);
2601 tc->do_thread(_cmThread);
2602 _cm->threads_do(tc);
2603 _cg1r->threads_do(tc); // also iterates over the sample thread
2604 if (G1StringDedup::is_enabled()) {
2605 G1StringDedup::threads_do(tc);
2606 }
2607 }
2608
2609 void G1CollectedHeap::print_tracing_info() const {
2610 g1_rem_set()->print_summary_info();
2611 concurrent_mark()->print_summary_info();
2612 }
2613
2614 #ifndef PRODUCT
2615 // Helpful for debugging RSet issues.
2616
2617 class PrintRSetsClosure : public HeapRegionClosure {
2618 private:
2619 const char* _msg;
2620 size_t _occupied_sum;
2621
2622 public:
2623 bool doHeapRegion(HeapRegion* r) {
2624 HeapRegionRemSet* hrrs = r->rem_set();
2625 size_t occupied = hrrs->occupied();
2626 _occupied_sum += occupied;
2627
2628 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2629 if (occupied == 0) {
2630 tty->print_cr(" RSet is empty");
2631 } else {
2632 hrrs->print();
2633 }
2634 tty->print_cr("----------");
2635 return false;
2636 }
2637
2638 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2639 tty->cr();
2640 tty->print_cr("========================================");
2641 tty->print_cr("%s", msg);
2642 tty->cr();
2643 }
2644
2645 ~PrintRSetsClosure() {
2646 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2647 tty->print_cr("========================================");
2648 tty->cr();
2649 }
2650 };
2651
2652 void G1CollectedHeap::print_cset_rsets() {
2653 PrintRSetsClosure cl("Printing CSet RSets");
2654 collection_set_iterate(&cl);
2655 }
2656
2657 void G1CollectedHeap::print_all_rsets() {
2658 PrintRSetsClosure cl("Printing All RSets");;
2659 heap_region_iterate(&cl);
2660 }
2661 #endif // PRODUCT
2662
2663 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2664
2665 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2666 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2667 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2668
2669 size_t eden_capacity_bytes =
2670 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2671
2672 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2673 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2674 eden_capacity_bytes, survivor_used_bytes, num_regions());
2675 }
2676
2677 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2678 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2679 stats->unused(), stats->used(), stats->region_end_waste(),
2680 stats->regions_filled(), stats->direct_allocated(),
2681 stats->failure_used(), stats->failure_waste());
2682 }
2683
2684 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2685 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2686 gc_tracer->report_gc_heap_summary(when, heap_summary);
2687
2688 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2689 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2690 }
2691
2692 G1CollectedHeap* G1CollectedHeap::heap() {
2693 CollectedHeap* heap = Universe::heap();
2694 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2695 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2696 return (G1CollectedHeap*)heap;
2697 }
2698
2699 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2700 // always_do_update_barrier = false;
2701 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2702
2703 double start = os::elapsedTime();
2704 // Fill TLAB's and such
2705 accumulate_statistics_all_tlabs();
2706 ensure_parsability(true);
2707 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2708
2709 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2710 }
2711
2712 void G1CollectedHeap::gc_epilogue(bool full) {
2713 // we are at the end of the GC. Total collections has already been increased.
2714 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2715
2716 // FIXME: what is this about?
2717 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2718 // is set.
2719 #if defined(COMPILER2) || INCLUDE_JVMCI
2720 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2721 #endif
2722 // always_do_update_barrier = true;
2723
2724 double start = os::elapsedTime();
2725 resize_all_tlabs();
2726 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2727
2728 allocation_context_stats().update(full);
2729
2730 // We have just completed a GC. Update the soft reference
2731 // policy with the new heap occupancy
2732 Universe::update_heap_info_at_gc();
2733 }
2734
2735 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2736 uint gc_count_before,
2737 bool* succeeded,
2738 GCCause::Cause gc_cause) {
2739 assert_heap_not_locked_and_not_at_safepoint();
2740 VM_G1IncCollectionPause op(gc_count_before,
2741 word_size,
2742 false, /* should_initiate_conc_mark */
2743 g1_policy()->max_pause_time_ms(),
2744 gc_cause);
2745
2746 op.set_allocation_context(AllocationContext::current());
2747 VMThread::execute(&op);
2748
2749 HeapWord* result = op.result();
2750 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2751 assert(result == NULL || ret_succeeded,
2752 "the result should be NULL if the VM did not succeed");
2753 *succeeded = ret_succeeded;
2754
2755 assert_heap_not_locked();
2756 return result;
2757 }
2758
2759 void
2760 G1CollectedHeap::doConcurrentMark() {
2761 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2762 if (!_cmThread->in_progress()) {
2763 _cmThread->set_started();
2764 CGC_lock->notify();
2765 }
2766 }
2767
2768 size_t G1CollectedHeap::pending_card_num() {
2769 size_t extra_cards = 0;
2770 JavaThread *curr = Threads::first();
2771 while (curr != NULL) {
2772 DirtyCardQueue& dcq = curr->dirty_card_queue();
2773 extra_cards += dcq.size();
2774 curr = curr->next();
2775 }
2776 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2777 size_t buffer_size = dcqs.buffer_size();
2778 size_t buffer_num = dcqs.completed_buffers_num();
2779
2780 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2781 // in bytes - not the number of 'entries'. We need to convert
2782 // into a number of cards.
2783 return (buffer_size * buffer_num + extra_cards) / oopSize;
2784 }
2785
2786 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2787 private:
2788 size_t _total_humongous;
2789 size_t _candidate_humongous;
2790
2791 DirtyCardQueue _dcq;
2792
2793 // We don't nominate objects with many remembered set entries, on
2794 // the assumption that such objects are likely still live.
2795 bool is_remset_small(HeapRegion* region) const {
2796 HeapRegionRemSet* const rset = region->rem_set();
2797 return G1EagerReclaimHumongousObjectsWithStaleRefs
2798 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2799 : rset->is_empty();
2800 }
2801
2802 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2803 assert(region->is_starts_humongous(), "Must start a humongous object");
2804
2805 oop obj = oop(region->bottom());
2806
2807 // Dead objects cannot be eager reclaim candidates. Due to class
2808 // unloading it is unsafe to query their classes so we return early.
2809 if (heap->is_obj_dead(obj, region)) {
2810 return false;
2811 }
2812
2813 // Candidate selection must satisfy the following constraints
2814 // while concurrent marking is in progress:
2815 //
2816 // * In order to maintain SATB invariants, an object must not be
2817 // reclaimed if it was allocated before the start of marking and
2818 // has not had its references scanned. Such an object must have
2819 // its references (including type metadata) scanned to ensure no
2820 // live objects are missed by the marking process. Objects
2821 // allocated after the start of concurrent marking don't need to
2822 // be scanned.
2823 //
2824 // * An object must not be reclaimed if it is on the concurrent
2825 // mark stack. Objects allocated after the start of concurrent
2826 // marking are never pushed on the mark stack.
2827 //
2828 // Nominating only objects allocated after the start of concurrent
2829 // marking is sufficient to meet both constraints. This may miss
2830 // some objects that satisfy the constraints, but the marking data
2831 // structures don't support efficiently performing the needed
2832 // additional tests or scrubbing of the mark stack.
2833 //
2834 // However, we presently only nominate is_typeArray() objects.
2835 // A humongous object containing references induces remembered
2836 // set entries on other regions. In order to reclaim such an
2837 // object, those remembered sets would need to be cleaned up.
2838 //
2839 // We also treat is_typeArray() objects specially, allowing them
2840 // to be reclaimed even if allocated before the start of
2841 // concurrent mark. For this we rely on mark stack insertion to
2842 // exclude is_typeArray() objects, preventing reclaiming an object
2843 // that is in the mark stack. We also rely on the metadata for
2844 // such objects to be built-in and so ensured to be kept live.
2845 // Frequent allocation and drop of large binary blobs is an
2846 // important use case for eager reclaim, and this special handling
2847 // may reduce needed headroom.
2848
2849 return obj->is_typeArray() && is_remset_small(region);
2850 }
2851
2852 public:
2853 RegisterHumongousWithInCSetFastTestClosure()
2854 : _total_humongous(0),
2855 _candidate_humongous(0),
2856 _dcq(&JavaThread::dirty_card_queue_set()) {
2857 }
2858
2859 virtual bool doHeapRegion(HeapRegion* r) {
2860 if (!r->is_starts_humongous()) {
2861 return false;
2862 }
2863 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2864
2865 bool is_candidate = humongous_region_is_candidate(g1h, r);
2866 uint rindex = r->hrm_index();
2867 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2868 if (is_candidate) {
2869 _candidate_humongous++;
2870 g1h->register_humongous_region_with_cset(rindex);
2871 // Is_candidate already filters out humongous object with large remembered sets.
2872 // If we have a humongous object with a few remembered sets, we simply flush these
2873 // remembered set entries into the DCQS. That will result in automatic
2874 // re-evaluation of their remembered set entries during the following evacuation
2875 // phase.
2876 if (!r->rem_set()->is_empty()) {
2877 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2878 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2879 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2880 HeapRegionRemSetIterator hrrs(r->rem_set());
2881 size_t card_index;
2882 while (hrrs.has_next(card_index)) {
2883 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2884 // The remembered set might contain references to already freed
2885 // regions. Filter out such entries to avoid failing card table
2886 // verification.
2887 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2888 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2889 *card_ptr = CardTableModRefBS::dirty_card_val();
2890 _dcq.enqueue(card_ptr);
2891 }
2892 }
2893 }
2894 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2895 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2896 hrrs.n_yielded(), r->rem_set()->occupied());
2897 r->rem_set()->clear_locked();
2898 }
2899 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2900 }
2901 _total_humongous++;
2902
2903 return false;
2904 }
2905
2906 size_t total_humongous() const { return _total_humongous; }
2907 size_t candidate_humongous() const { return _candidate_humongous; }
2908
2909 void flush_rem_set_entries() { _dcq.flush(); }
2910 };
2911
2912 void G1CollectedHeap::register_humongous_regions_with_cset() {
2913 if (!G1EagerReclaimHumongousObjects) {
2914 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2915 return;
2916 }
2917 double time = os::elapsed_counter();
2918
2919 // Collect reclaim candidate information and register candidates with cset.
2920 RegisterHumongousWithInCSetFastTestClosure cl;
2921 heap_region_iterate(&cl);
2922
2923 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2924 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2925 cl.total_humongous(),
2926 cl.candidate_humongous());
2927 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2928
2929 // Finally flush all remembered set entries to re-check into the global DCQS.
2930 cl.flush_rem_set_entries();
2931 }
2932
2933 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2934 public:
2935 bool doHeapRegion(HeapRegion* hr) {
2936 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2937 hr->verify_rem_set();
2938 }
2939 return false;
2940 }
2941 };
2942
2943 uint G1CollectedHeap::num_task_queues() const {
2944 return _task_queues->size();
2945 }
2946
2947 #if TASKQUEUE_STATS
2948 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2949 st->print_raw_cr("GC Task Stats");
2950 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2951 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2952 }
2953
2954 void G1CollectedHeap::print_taskqueue_stats() const {
2955 if (!log_is_enabled(Trace, gc, task, stats)) {
2956 return;
2957 }
2958 Log(gc, task, stats) log;
2959 ResourceMark rm;
2960 outputStream* st = log.trace_stream();
2961
2962 print_taskqueue_stats_hdr(st);
2963
2964 TaskQueueStats totals;
2965 const uint n = num_task_queues();
2966 for (uint i = 0; i < n; ++i) {
2967 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2968 totals += task_queue(i)->stats;
2969 }
2970 st->print_raw("tot "); totals.print(st); st->cr();
2971
2972 DEBUG_ONLY(totals.verify());
2973 }
2974
2975 void G1CollectedHeap::reset_taskqueue_stats() {
2976 const uint n = num_task_queues();
2977 for (uint i = 0; i < n; ++i) {
2978 task_queue(i)->stats.reset();
2979 }
2980 }
2981 #endif // TASKQUEUE_STATS
2982
2983 void G1CollectedHeap::wait_for_root_region_scanning() {
2984 double scan_wait_start = os::elapsedTime();
2985 // We have to wait until the CM threads finish scanning the
2986 // root regions as it's the only way to ensure that all the
2987 // objects on them have been correctly scanned before we start
2988 // moving them during the GC.
2989 bool waited = _cm->root_regions()->wait_until_scan_finished();
2990 double wait_time_ms = 0.0;
2991 if (waited) {
2992 double scan_wait_end = os::elapsedTime();
2993 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2994 }
2995 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2996 }
2997
2998 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2999 private:
3000 G1HRPrinter* _hr_printer;
3001 public:
3002 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
3003
3004 virtual bool doHeapRegion(HeapRegion* r) {
3005 _hr_printer->cset(r);
3006 return false;
3007 }
3008 };
3009
3010 void G1CollectedHeap::start_new_collection_set() {
3011 collection_set()->start_incremental_building();
3012
3013 clear_cset_fast_test();
3014
3015 guarantee(_eden.length() == 0, "eden should have been cleared");
3016 g1_policy()->transfer_survivors_to_cset(survivor());
3017 }
3018
3019 bool
3020 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3021 assert_at_safepoint(true /* should_be_vm_thread */);
3022 guarantee(!is_gc_active(), "collection is not reentrant");
3023
3024 if (GCLocker::check_active_before_gc()) {
3025 return false;
3026 }
3027
3028 _gc_timer_stw->register_gc_start();
3029
3030 GCIdMark gc_id_mark;
3031 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3032
3033 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3034 ResourceMark rm;
3035
3036 g1_policy()->note_gc_start();
3037
3038 wait_for_root_region_scanning();
3039
3040 print_heap_before_gc();
3041 print_heap_regions();
3042 trace_heap_before_gc(_gc_tracer_stw);
3043
3044 _verifier->verify_region_sets_optional();
3045 _verifier->verify_dirty_young_regions();
3046
3047 // We should not be doing initial mark unless the conc mark thread is running
3048 if (!_cmThread->should_terminate()) {
3049 // This call will decide whether this pause is an initial-mark
3050 // pause. If it is, during_initial_mark_pause() will return true
3051 // for the duration of this pause.
3052 g1_policy()->decide_on_conc_mark_initiation();
3053 }
3054
3055 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3056 assert(!collector_state()->during_initial_mark_pause() ||
3057 collector_state()->gcs_are_young(), "sanity");
3058
3059 // We also do not allow mixed GCs during marking.
3060 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3061
3062 // Record whether this pause is an initial mark. When the current
3063 // thread has completed its logging output and it's safe to signal
3064 // the CM thread, the flag's value in the policy has been reset.
3065 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3066
3067 // Inner scope for scope based logging, timers, and stats collection
3068 {
3069 EvacuationInfo evacuation_info;
3070
3071 if (collector_state()->during_initial_mark_pause()) {
3072 // We are about to start a marking cycle, so we increment the
3073 // full collection counter.
3074 increment_old_marking_cycles_started();
3075 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3076 }
3077
3078 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3079
3080 GCTraceCPUTime tcpu;
3081
3082 FormatBuffer<> gc_string("Pause ");
3083 if (collector_state()->during_initial_mark_pause()) {
3084 gc_string.append("Initial Mark");
3085 } else if (collector_state()->gcs_are_young()) {
3086 gc_string.append("Young");
3087 } else {
3088 gc_string.append("Mixed");
3089 }
3090 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3091
3092 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3093 workers()->active_workers(),
3094 Threads::number_of_non_daemon_threads());
3095 workers()->update_active_workers(active_workers);
3096 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3097
3098 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3099 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3100
3101 // If the secondary_free_list is not empty, append it to the
3102 // free_list. No need to wait for the cleanup operation to finish;
3103 // the region allocation code will check the secondary_free_list
3104 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3105 // set, skip this step so that the region allocation code has to
3106 // get entries from the secondary_free_list.
3107 if (!G1StressConcRegionFreeing) {
3108 append_secondary_free_list_if_not_empty_with_lock();
3109 }
3110
3111 G1HeapTransition heap_transition(this);
3112 size_t heap_used_bytes_before_gc = used();
3113
3114 // Don't dynamically change the number of GC threads this early. A value of
3115 // 0 is used to indicate serial work. When parallel work is done,
3116 // it will be set.
3117
3118 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3119 IsGCActiveMark x;
3120
3121 gc_prologue(false);
3122 increment_total_collections(false /* full gc */);
3123 increment_gc_time_stamp();
3124
3125 if (VerifyRememberedSets) {
3126 log_info(gc, verify)("[Verifying RemSets before GC]");
3127 VerifyRegionRemSetClosure v_cl;
3128 heap_region_iterate(&v_cl);
3129 }
3130
3131 _verifier->verify_before_gc();
3132
3133 _verifier->check_bitmaps("GC Start");
3134
3135 #if defined(COMPILER2) || INCLUDE_JVMCI
3136 DerivedPointerTable::clear();
3137 #endif
3138
3139 // Please see comment in g1CollectedHeap.hpp and
3140 // G1CollectedHeap::ref_processing_init() to see how
3141 // reference processing currently works in G1.
3142
3143 // Enable discovery in the STW reference processor
3144 if (g1_policy()->should_process_references()) {
3145 ref_processor_stw()->enable_discovery();
3146 } else {
3147 ref_processor_stw()->disable_discovery();
3148 }
3149
3150 {
3151 // We want to temporarily turn off discovery by the
3152 // CM ref processor, if necessary, and turn it back on
3153 // on again later if we do. Using a scoped
3154 // NoRefDiscovery object will do this.
3155 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3156
3157 // Forget the current alloc region (we might even choose it to be part
3158 // of the collection set!).
3159 _allocator->release_mutator_alloc_region();
3160
3161 // This timing is only used by the ergonomics to handle our pause target.
3162 // It is unclear why this should not include the full pause. We will
3163 // investigate this in CR 7178365.
3164 //
3165 // Preserving the old comment here if that helps the investigation:
3166 //
3167 // The elapsed time induced by the start time below deliberately elides
3168 // the possible verification above.
3169 double sample_start_time_sec = os::elapsedTime();
3170
3171 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3172
3173 if (collector_state()->during_initial_mark_pause()) {
3174 concurrent_mark()->checkpointRootsInitialPre();
3175 }
3176
3177 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3178
3179 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3180
3181 // Make sure the remembered sets are up to date. This needs to be
3182 // done before register_humongous_regions_with_cset(), because the
3183 // remembered sets are used there to choose eager reclaim candidates.
3184 // If the remembered sets are not up to date we might miss some
3185 // entries that need to be handled.
3186 g1_rem_set()->cleanupHRRS();
3187
3188 register_humongous_regions_with_cset();
3189
3190 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3191
3192 // We call this after finalize_cset() to
3193 // ensure that the CSet has been finalized.
3194 _cm->verify_no_cset_oops();
3195
3196 if (_hr_printer.is_active()) {
3197 G1PrintCollectionSetClosure cl(&_hr_printer);
3198 _collection_set.iterate(&cl);
3199 }
3200
3201 // Initialize the GC alloc regions.
3202 _allocator->init_gc_alloc_regions(evacuation_info);
3203
3204 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3205 pre_evacuate_collection_set();
3206
3207 // Actually do the work...
3208 evacuate_collection_set(evacuation_info, &per_thread_states);
3209
3210 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3211
3212 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3213 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3214
3215 eagerly_reclaim_humongous_regions();
3216
3217 record_obj_copy_mem_stats();
3218 _survivor_evac_stats.adjust_desired_plab_sz();
3219 _old_evac_stats.adjust_desired_plab_sz();
3220
3221 double start = os::elapsedTime();
3222 start_new_collection_set();
3223 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3224
3225 if (evacuation_failed()) {
3226 set_used(recalculate_used());
3227 if (_archive_allocator != NULL) {
3228 _archive_allocator->clear_used();
3229 }
3230 for (uint i = 0; i < ParallelGCThreads; i++) {
3231 if (_evacuation_failed_info_array[i].has_failed()) {
3232 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3233 }
3234 }
3235 } else {
3236 // The "used" of the the collection set have already been subtracted
3237 // when they were freed. Add in the bytes evacuated.
3238 increase_used(g1_policy()->bytes_copied_during_gc());
3239 }
3240
3241 if (collector_state()->during_initial_mark_pause()) {
3242 // We have to do this before we notify the CM threads that
3243 // they can start working to make sure that all the
3244 // appropriate initialization is done on the CM object.
3245 concurrent_mark()->checkpointRootsInitialPost();
3246 collector_state()->set_mark_in_progress(true);
3247 // Note that we don't actually trigger the CM thread at
3248 // this point. We do that later when we're sure that
3249 // the current thread has completed its logging output.
3250 }
3251
3252 allocate_dummy_regions();
3253
3254 _allocator->init_mutator_alloc_region();
3255
3256 {
3257 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3258 if (expand_bytes > 0) {
3259 size_t bytes_before = capacity();
3260 // No need for an ergo logging here,
3261 // expansion_amount() does this when it returns a value > 0.
3262 double expand_ms;
3263 if (!expand(expand_bytes, _workers, &expand_ms)) {
3264 // We failed to expand the heap. Cannot do anything about it.
3265 }
3266 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3267 }
3268 }
3269
3270 // We redo the verification but now wrt to the new CSet which
3271 // has just got initialized after the previous CSet was freed.
3272 _cm->verify_no_cset_oops();
3273
3274 // This timing is only used by the ergonomics to handle our pause target.
3275 // It is unclear why this should not include the full pause. We will
3276 // investigate this in CR 7178365.
3277 double sample_end_time_sec = os::elapsedTime();
3278 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3279 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3280 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3281
3282 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3283 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3284
3285 MemoryService::track_memory_usage();
3286
3287 // In prepare_for_verify() below we'll need to scan the deferred
3288 // update buffers to bring the RSets up-to-date if
3289 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3290 // the update buffers we'll probably need to scan cards on the
3291 // regions we just allocated to (i.e., the GC alloc
3292 // regions). However, during the last GC we called
3293 // set_saved_mark() on all the GC alloc regions, so card
3294 // scanning might skip the [saved_mark_word()...top()] area of
3295 // those regions (i.e., the area we allocated objects into
3296 // during the last GC). But it shouldn't. Given that
3297 // saved_mark_word() is conditional on whether the GC time stamp
3298 // on the region is current or not, by incrementing the GC time
3299 // stamp here we invalidate all the GC time stamps on all the
3300 // regions and saved_mark_word() will simply return top() for
3301 // all the regions. This is a nicer way of ensuring this rather
3302 // than iterating over the regions and fixing them. In fact, the
3303 // GC time stamp increment here also ensures that
3304 // saved_mark_word() will return top() between pauses, i.e.,
3305 // during concurrent refinement. So we don't need the
3306 // is_gc_active() check to decided which top to use when
3307 // scanning cards (see CR 7039627).
3308 increment_gc_time_stamp();
3309
3310 if (VerifyRememberedSets) {
3311 log_info(gc, verify)("[Verifying RemSets after GC]");
3312 VerifyRegionRemSetClosure v_cl;
3313 heap_region_iterate(&v_cl);
3314 }
3315
3316 _verifier->verify_after_gc();
3317 _verifier->check_bitmaps("GC End");
3318
3319 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3320 ref_processor_stw()->verify_no_references_recorded();
3321
3322 // CM reference discovery will be re-enabled if necessary.
3323 }
3324
3325 #ifdef TRACESPINNING
3326 ParallelTaskTerminator::print_termination_counts();
3327 #endif
3328
3329 gc_epilogue(false);
3330 }
3331
3332 // Print the remainder of the GC log output.
3333 if (evacuation_failed()) {
3334 log_info(gc)("To-space exhausted");
3335 }
3336
3337 g1_policy()->print_phases();
3338 heap_transition.print();
3339
3340 // It is not yet to safe to tell the concurrent mark to
3341 // start as we have some optional output below. We don't want the
3342 // output from the concurrent mark thread interfering with this
3343 // logging output either.
3344
3345 _hrm.verify_optional();
3346 _verifier->verify_region_sets_optional();
3347
3348 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3349 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3350
3351 print_heap_after_gc();
3352 print_heap_regions();
3353 trace_heap_after_gc(_gc_tracer_stw);
3354
3355 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3356 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3357 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3358 // before any GC notifications are raised.
3359 g1mm()->update_sizes();
3360
3361 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3362 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3363 _gc_timer_stw->register_gc_end();
3364 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3365 }
3366 // It should now be safe to tell the concurrent mark thread to start
3367 // without its logging output interfering with the logging output
3368 // that came from the pause.
3369
3370 if (should_start_conc_mark) {
3371 // CAUTION: after the doConcurrentMark() call below,
3372 // the concurrent marking thread(s) could be running
3373 // concurrently with us. Make sure that anything after
3374 // this point does not assume that we are the only GC thread
3375 // running. Note: of course, the actual marking work will
3376 // not start until the safepoint itself is released in
3377 // SuspendibleThreadSet::desynchronize().
3378 doConcurrentMark();
3379 }
3380
3381 return true;
3382 }
3383
3384 void G1CollectedHeap::remove_self_forwarding_pointers() {
3385 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3386 workers()->run_task(&rsfp_task);
3387 }
3388
3389 void G1CollectedHeap::restore_after_evac_failure() {
3390 double remove_self_forwards_start = os::elapsedTime();
3391
3392 remove_self_forwarding_pointers();
3393 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3394 _preserved_marks_set.restore(&task_executor);
3395
3396 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3397 }
3398
3399 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3400 if (!_evacuation_failed) {
3401 _evacuation_failed = true;
3402 }
3403
3404 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3405 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3406 }
3407
3408 bool G1ParEvacuateFollowersClosure::offer_termination() {
3409 G1ParScanThreadState* const pss = par_scan_state();
3410 start_term_time();
3411 const bool res = terminator()->offer_termination();
3412 end_term_time();
3413 return res;
3414 }
3415
3416 void G1ParEvacuateFollowersClosure::do_void() {
3417 G1ParScanThreadState* const pss = par_scan_state();
3418 pss->trim_queue();
3419 do {
3420 pss->steal_and_trim_queue(queues());
3421 } while (!offer_termination());
3422 }
3423
3424 class G1ParTask : public AbstractGangTask {
3425 protected:
3426 G1CollectedHeap* _g1h;
3427 G1ParScanThreadStateSet* _pss;
3428 RefToScanQueueSet* _queues;
3429 G1RootProcessor* _root_processor;
3430 ParallelTaskTerminator _terminator;
3431 uint _n_workers;
3432
3433 public:
3434 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3435 : AbstractGangTask("G1 collection"),
3436 _g1h(g1h),
3437 _pss(per_thread_states),
3438 _queues(task_queues),
3439 _root_processor(root_processor),
3440 _terminator(n_workers, _queues),
3441 _n_workers(n_workers)
3442 {}
3443
3444 void work(uint worker_id) {
3445 if (worker_id >= _n_workers) return; // no work needed this round
3446
3447 double start_sec = os::elapsedTime();
3448 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3449
3450 {
3451 ResourceMark rm;
3452 HandleMark hm;
3453
3454 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3455
3456 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3457 pss->set_ref_processor(rp);
3458
3459 double start_strong_roots_sec = os::elapsedTime();
3460
3461 _root_processor->evacuate_roots(pss->closures(), worker_id);
3462
3463 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3464
3465 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3466 // treating the nmethods visited to act as roots for concurrent marking.
3467 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3468 // objects copied by the current evacuation.
3469 _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3470 pss->closures()->weak_codeblobs(),
3471 worker_id);
3472
3473 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3474
3475 double term_sec = 0.0;
3476 size_t evac_term_attempts = 0;
3477 {
3478 double start = os::elapsedTime();
3479 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3480 evac.do_void();
3481
3482 evac_term_attempts = evac.term_attempts();
3483 term_sec = evac.term_time();
3484 double elapsed_sec = os::elapsedTime() - start;
3485 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3486 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3487 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3488 }
3489
3490 assert(pss->queue_is_empty(), "should be empty");
3491
3492 if (log_is_enabled(Debug, gc, task, stats)) {
3493 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3494 size_t lab_waste;
3495 size_t lab_undo_waste;
3496 pss->waste(lab_waste, lab_undo_waste);
3497 _g1h->print_termination_stats(worker_id,
3498 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3499 strong_roots_sec * 1000.0, /* strong roots time */
3500 term_sec * 1000.0, /* evac term time */
3501 evac_term_attempts, /* evac term attempts */
3502 lab_waste, /* alloc buffer waste */
3503 lab_undo_waste /* undo waste */
3504 );
3505 }
3506
3507 // Close the inner scope so that the ResourceMark and HandleMark
3508 // destructors are executed here and are included as part of the
3509 // "GC Worker Time".
3510 }
3511 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3512 }
3513 };
3514
3515 void G1CollectedHeap::print_termination_stats_hdr() {
3516 log_debug(gc, task, stats)("GC Termination Stats");
3517 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3518 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3519 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3520 }
3521
3522 void G1CollectedHeap::print_termination_stats(uint worker_id,
3523 double elapsed_ms,
3524 double strong_roots_ms,
3525 double term_ms,
3526 size_t term_attempts,
3527 size_t alloc_buffer_waste,
3528 size_t undo_waste) const {
3529 log_debug(gc, task, stats)
3530 ("%3d %9.2f %9.2f %6.2f "
3531 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3532 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3533 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3534 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3535 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3536 alloc_buffer_waste * HeapWordSize / K,
3537 undo_waste * HeapWordSize / K);
3538 }
3539
3540 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3541 private:
3542 BoolObjectClosure* _is_alive;
3543 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3544
3545 int _initial_string_table_size;
3546 int _initial_symbol_table_size;
3547
3548 bool _process_strings;
3549 int _strings_processed;
3550 int _strings_removed;
3551
3552 bool _process_symbols;
3553 int _symbols_processed;
3554 int _symbols_removed;
3555
3556 bool _process_string_dedup;
3557
3558 public:
3559 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3560 AbstractGangTask("String/Symbol Unlinking"),
3561 _is_alive(is_alive),
3562 _dedup_closure(is_alive, NULL, false),
3563 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3564 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3565 _process_string_dedup(process_string_dedup) {
3566
3567 _initial_string_table_size = StringTable::the_table()->table_size();
3568 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3569 if (process_strings) {
3570 StringTable::clear_parallel_claimed_index();
3571 }
3572 if (process_symbols) {
3573 SymbolTable::clear_parallel_claimed_index();
3574 }
3575 }
3576
3577 ~G1StringAndSymbolCleaningTask() {
3578 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3579 "claim value %d after unlink less than initial string table size %d",
3580 StringTable::parallel_claimed_index(), _initial_string_table_size);
3581 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3582 "claim value %d after unlink less than initial symbol table size %d",
3583 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3584
3585 log_info(gc, stringtable)(
3586 "Cleaned string and symbol table, "
3587 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3588 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3589 strings_processed(), strings_removed(),
3590 symbols_processed(), symbols_removed());
3591 }
3592
3593 void work(uint worker_id) {
3594 int strings_processed = 0;
3595 int strings_removed = 0;
3596 int symbols_processed = 0;
3597 int symbols_removed = 0;
3598 if (_process_strings) {
3599 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3600 Atomic::add(strings_processed, &_strings_processed);
3601 Atomic::add(strings_removed, &_strings_removed);
3602 }
3603 if (_process_symbols) {
3604 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3605 Atomic::add(symbols_processed, &_symbols_processed);
3606 Atomic::add(symbols_removed, &_symbols_removed);
3607 }
3608 if (_process_string_dedup) {
3609 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3610 }
3611 }
3612
3613 size_t strings_processed() const { return (size_t)_strings_processed; }
3614 size_t strings_removed() const { return (size_t)_strings_removed; }
3615
3616 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3617 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3618 };
3619
3620 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3621 private:
3622 static Monitor* _lock;
3623
3624 BoolObjectClosure* const _is_alive;
3625 const bool _unloading_occurred;
3626 const uint _num_workers;
3627
3628 // Variables used to claim nmethods.
3629 CompiledMethod* _first_nmethod;
3630 volatile CompiledMethod* _claimed_nmethod;
3631
3632 // The list of nmethods that need to be processed by the second pass.
3633 volatile CompiledMethod* _postponed_list;
3634 volatile uint _num_entered_barrier;
3635
3636 public:
3637 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3638 _is_alive(is_alive),
3639 _unloading_occurred(unloading_occurred),
3640 _num_workers(num_workers),
3641 _first_nmethod(NULL),
3642 _claimed_nmethod(NULL),
3643 _postponed_list(NULL),
3644 _num_entered_barrier(0)
3645 {
3646 CompiledMethod::increase_unloading_clock();
3647 // Get first alive nmethod
3648 CompiledMethodIterator iter = CompiledMethodIterator();
3649 if(iter.next_alive()) {
3650 _first_nmethod = iter.method();
3651 }
3652 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3653 }
3654
3655 ~G1CodeCacheUnloadingTask() {
3656 CodeCache::verify_clean_inline_caches();
3657
3658 CodeCache::set_needs_cache_clean(false);
3659 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3660
3661 CodeCache::verify_icholder_relocations();
3662 }
3663
3664 private:
3665 void add_to_postponed_list(CompiledMethod* nm) {
3666 CompiledMethod* old;
3667 do {
3668 old = (CompiledMethod*)_postponed_list;
3669 nm->set_unloading_next(old);
3670 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3671 }
3672
3673 void clean_nmethod(CompiledMethod* nm) {
3674 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3675
3676 if (postponed) {
3677 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3678 add_to_postponed_list(nm);
3679 }
3680
3681 // Mark that this thread has been cleaned/unloaded.
3682 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3683 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3684 }
3685
3686 void clean_nmethod_postponed(CompiledMethod* nm) {
3687 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3688 }
3689
3690 static const int MaxClaimNmethods = 16;
3691
3692 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3693 CompiledMethod* first;
3694 CompiledMethodIterator last;
3695
3696 do {
3697 *num_claimed_nmethods = 0;
3698
3699 first = (CompiledMethod*)_claimed_nmethod;
3700 last = CompiledMethodIterator(first);
3701
3702 if (first != NULL) {
3703
3704 for (int i = 0; i < MaxClaimNmethods; i++) {
3705 if (!last.next_alive()) {
3706 break;
3707 }
3708 claimed_nmethods[i] = last.method();
3709 (*num_claimed_nmethods)++;
3710 }
3711 }
3712
3713 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3714 }
3715
3716 CompiledMethod* claim_postponed_nmethod() {
3717 CompiledMethod* claim;
3718 CompiledMethod* next;
3719
3720 do {
3721 claim = (CompiledMethod*)_postponed_list;
3722 if (claim == NULL) {
3723 return NULL;
3724 }
3725
3726 next = claim->unloading_next();
3727
3728 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3729
3730 return claim;
3731 }
3732
3733 public:
3734 // Mark that we're done with the first pass of nmethod cleaning.
3735 void barrier_mark(uint worker_id) {
3736 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3737 _num_entered_barrier++;
3738 if (_num_entered_barrier == _num_workers) {
3739 ml.notify_all();
3740 }
3741 }
3742
3743 // See if we have to wait for the other workers to
3744 // finish their first-pass nmethod cleaning work.
3745 void barrier_wait(uint worker_id) {
3746 if (_num_entered_barrier < _num_workers) {
3747 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3748 while (_num_entered_barrier < _num_workers) {
3749 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3750 }
3751 }
3752 }
3753
3754 // Cleaning and unloading of nmethods. Some work has to be postponed
3755 // to the second pass, when we know which nmethods survive.
3756 void work_first_pass(uint worker_id) {
3757 // The first nmethods is claimed by the first worker.
3758 if (worker_id == 0 && _first_nmethod != NULL) {
3759 clean_nmethod(_first_nmethod);
3760 _first_nmethod = NULL;
3761 }
3762
3763 int num_claimed_nmethods;
3764 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3765
3766 while (true) {
3767 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3768
3769 if (num_claimed_nmethods == 0) {
3770 break;
3771 }
3772
3773 for (int i = 0; i < num_claimed_nmethods; i++) {
3774 clean_nmethod(claimed_nmethods[i]);
3775 }
3776 }
3777 }
3778
3779 void work_second_pass(uint worker_id) {
3780 CompiledMethod* nm;
3781 // Take care of postponed nmethods.
3782 while ((nm = claim_postponed_nmethod()) != NULL) {
3783 clean_nmethod_postponed(nm);
3784 }
3785 }
3786 };
3787
3788 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3789
3790 class G1KlassCleaningTask : public StackObj {
3791 BoolObjectClosure* _is_alive;
3792 volatile jint _clean_klass_tree_claimed;
3793 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3794
3795 public:
3796 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3797 _is_alive(is_alive),
3798 _clean_klass_tree_claimed(0),
3799 _klass_iterator() {
3800 }
3801
3802 private:
3803 bool claim_clean_klass_tree_task() {
3804 if (_clean_klass_tree_claimed) {
3805 return false;
3806 }
3807
3808 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3809 }
3810
3811 InstanceKlass* claim_next_klass() {
3812 Klass* klass;
3813 do {
3814 klass =_klass_iterator.next_klass();
3815 } while (klass != NULL && !klass->is_instance_klass());
3816
3817 // this can be null so don't call InstanceKlass::cast
3818 return static_cast<InstanceKlass*>(klass);
3819 }
3820
3821 public:
3822
3823 void clean_klass(InstanceKlass* ik) {
3824 ik->clean_weak_instanceklass_links(_is_alive);
3825 }
3826
3827 void work() {
3828 ResourceMark rm;
3829
3830 // One worker will clean the subklass/sibling klass tree.
3831 if (claim_clean_klass_tree_task()) {
3832 Klass::clean_subklass_tree(_is_alive);
3833 }
3834
3835 // All workers will help cleaning the classes,
3836 InstanceKlass* klass;
3837 while ((klass = claim_next_klass()) != NULL) {
3838 clean_klass(klass);
3839 }
3840 }
3841 };
3842
3843 // To minimize the remark pause times, the tasks below are done in parallel.
3844 class G1ParallelCleaningTask : public AbstractGangTask {
3845 private:
3846 G1StringAndSymbolCleaningTask _string_symbol_task;
3847 G1CodeCacheUnloadingTask _code_cache_task;
3848 G1KlassCleaningTask _klass_cleaning_task;
3849
3850 public:
3851 // The constructor is run in the VMThread.
3852 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3853 AbstractGangTask("Parallel Cleaning"),
3854 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3855 _code_cache_task(num_workers, is_alive, unloading_occurred),
3856 _klass_cleaning_task(is_alive) {
3857 }
3858
3859 // The parallel work done by all worker threads.
3860 void work(uint worker_id) {
3861 // Do first pass of code cache cleaning.
3862 _code_cache_task.work_first_pass(worker_id);
3863
3864 // Let the threads mark that the first pass is done.
3865 _code_cache_task.barrier_mark(worker_id);
3866
3867 // Clean the Strings and Symbols.
3868 _string_symbol_task.work(worker_id);
3869
3870 // Wait for all workers to finish the first code cache cleaning pass.
3871 _code_cache_task.barrier_wait(worker_id);
3872
3873 // Do the second code cache cleaning work, which realize on
3874 // the liveness information gathered during the first pass.
3875 _code_cache_task.work_second_pass(worker_id);
3876
3877 // Clean all klasses that were not unloaded.
3878 _klass_cleaning_task.work();
3879 }
3880 };
3881
3882
3883 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3884 bool class_unloading_occurred) {
3885 uint n_workers = workers()->active_workers();
3886
3887 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3888 workers()->run_task(&g1_unlink_task);
3889 }
3890
3891 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3892 bool process_strings,
3893 bool process_symbols,
3894 bool process_string_dedup) {
3895 if (!process_strings && !process_symbols && !process_string_dedup) {
3896 // Nothing to clean.
3897 return;
3898 }
3899
3900 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3901 workers()->run_task(&g1_unlink_task);
3902
3903 }
3904
3905 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3906 private:
3907 DirtyCardQueueSet* _queue;
3908 G1CollectedHeap* _g1h;
3909 public:
3910 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3911 _queue(queue), _g1h(g1h) { }
3912
3913 virtual void work(uint worker_id) {
3914 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3915 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3916
3917 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3918 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3919
3920 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3921 }
3922 };
3923
3924 void G1CollectedHeap::redirty_logged_cards() {
3925 double redirty_logged_cards_start = os::elapsedTime();
3926
3927 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3928 dirty_card_queue_set().reset_for_par_iteration();
3929 workers()->run_task(&redirty_task);
3930
3931 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3932 dcq.merge_bufferlists(&dirty_card_queue_set());
3933 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3934
3935 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3936 }
3937
3938 // Weak Reference Processing support
3939
3940 // An always "is_alive" closure that is used to preserve referents.
3941 // If the object is non-null then it's alive. Used in the preservation
3942 // of referent objects that are pointed to by reference objects
3943 // discovered by the CM ref processor.
3944 class G1AlwaysAliveClosure: public BoolObjectClosure {
3945 G1CollectedHeap* _g1;
3946 public:
3947 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3948 bool do_object_b(oop p) {
3949 if (p != NULL) {
3950 return true;
3951 }
3952 return false;
3953 }
3954 };
3955
3956 bool G1STWIsAliveClosure::do_object_b(oop p) {
3957 // An object is reachable if it is outside the collection set,
3958 // or is inside and copied.
3959 return !_g1->is_in_cset(p) || p->is_forwarded();
3960 }
3961
3962 // Non Copying Keep Alive closure
3963 class G1KeepAliveClosure: public OopClosure {
3964 G1CollectedHeap* _g1;
3965 public:
3966 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3967 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3968 void do_oop(oop* p) {
3969 oop obj = *p;
3970 assert(obj != NULL, "the caller should have filtered out NULL values");
3971
3972 const InCSetState cset_state = _g1->in_cset_state(obj);
3973 if (!cset_state.is_in_cset_or_humongous()) {
3974 return;
3975 }
3976 if (cset_state.is_in_cset()) {
3977 assert( obj->is_forwarded(), "invariant" );
3978 *p = obj->forwardee();
3979 } else {
3980 assert(!obj->is_forwarded(), "invariant" );
3981 assert(cset_state.is_humongous(),
3982 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3983 _g1->set_humongous_is_live(obj);
3984 }
3985 }
3986 };
3987
3988 // Copying Keep Alive closure - can be called from both
3989 // serial and parallel code as long as different worker
3990 // threads utilize different G1ParScanThreadState instances
3991 // and different queues.
3992
3993 class G1CopyingKeepAliveClosure: public OopClosure {
3994 G1CollectedHeap* _g1h;
3995 OopClosure* _copy_non_heap_obj_cl;
3996 G1ParScanThreadState* _par_scan_state;
3997
3998 public:
3999 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4000 OopClosure* non_heap_obj_cl,
4001 G1ParScanThreadState* pss):
4002 _g1h(g1h),
4003 _copy_non_heap_obj_cl(non_heap_obj_cl),
4004 _par_scan_state(pss)
4005 {}
4006
4007 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4008 virtual void do_oop( oop* p) { do_oop_work(p); }
4009
4010 template <class T> void do_oop_work(T* p) {
4011 oop obj = oopDesc::load_decode_heap_oop(p);
4012
4013 if (_g1h->is_in_cset_or_humongous(obj)) {
4014 // If the referent object has been forwarded (either copied
4015 // to a new location or to itself in the event of an
4016 // evacuation failure) then we need to update the reference
4017 // field and, if both reference and referent are in the G1
4018 // heap, update the RSet for the referent.
4019 //
4020 // If the referent has not been forwarded then we have to keep
4021 // it alive by policy. Therefore we have copy the referent.
4022 //
4023 // If the reference field is in the G1 heap then we can push
4024 // on the PSS queue. When the queue is drained (after each
4025 // phase of reference processing) the object and it's followers
4026 // will be copied, the reference field set to point to the
4027 // new location, and the RSet updated. Otherwise we need to
4028 // use the the non-heap or metadata closures directly to copy
4029 // the referent object and update the pointer, while avoiding
4030 // updating the RSet.
4031
4032 if (_g1h->is_in_g1_reserved(p)) {
4033 _par_scan_state->push_on_queue(p);
4034 } else {
4035 assert(!Metaspace::contains((const void*)p),
4036 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4037 _copy_non_heap_obj_cl->do_oop(p);
4038 }
4039 }
4040 }
4041 };
4042
4043 // Serial drain queue closure. Called as the 'complete_gc'
4044 // closure for each discovered list in some of the
4045 // reference processing phases.
4046
4047 class G1STWDrainQueueClosure: public VoidClosure {
4048 protected:
4049 G1CollectedHeap* _g1h;
4050 G1ParScanThreadState* _par_scan_state;
4051
4052 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4053
4054 public:
4055 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4056 _g1h(g1h),
4057 _par_scan_state(pss)
4058 { }
4059
4060 void do_void() {
4061 G1ParScanThreadState* const pss = par_scan_state();
4062 pss->trim_queue();
4063 }
4064 };
4065
4066 // Parallel Reference Processing closures
4067
4068 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4069 // processing during G1 evacuation pauses.
4070
4071 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4072 private:
4073 G1CollectedHeap* _g1h;
4074 G1ParScanThreadStateSet* _pss;
4075 RefToScanQueueSet* _queues;
4076 WorkGang* _workers;
4077 uint _active_workers;
4078
4079 public:
4080 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4081 G1ParScanThreadStateSet* per_thread_states,
4082 WorkGang* workers,
4083 RefToScanQueueSet *task_queues,
4084 uint n_workers) :
4085 _g1h(g1h),
4086 _pss(per_thread_states),
4087 _queues(task_queues),
4088 _workers(workers),
4089 _active_workers(n_workers)
4090 {
4091 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4092 }
4093
4094 // Executes the given task using concurrent marking worker threads.
4095 virtual void execute(ProcessTask& task);
4096 virtual void execute(EnqueueTask& task);
4097 };
4098
4099 // Gang task for possibly parallel reference processing
4100
4101 class G1STWRefProcTaskProxy: public AbstractGangTask {
4102 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4103 ProcessTask& _proc_task;
4104 G1CollectedHeap* _g1h;
4105 G1ParScanThreadStateSet* _pss;
4106 RefToScanQueueSet* _task_queues;
4107 ParallelTaskTerminator* _terminator;
4108
4109 public:
4110 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4111 G1CollectedHeap* g1h,
4112 G1ParScanThreadStateSet* per_thread_states,
4113 RefToScanQueueSet *task_queues,
4114 ParallelTaskTerminator* terminator) :
4115 AbstractGangTask("Process reference objects in parallel"),
4116 _proc_task(proc_task),
4117 _g1h(g1h),
4118 _pss(per_thread_states),
4119 _task_queues(task_queues),
4120 _terminator(terminator)
4121 {}
4122
4123 virtual void work(uint worker_id) {
4124 // The reference processing task executed by a single worker.
4125 ResourceMark rm;
4126 HandleMark hm;
4127
4128 G1STWIsAliveClosure is_alive(_g1h);
4129
4130 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4131 pss->set_ref_processor(NULL);
4132
4133 // Keep alive closure.
4134 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4135
4136 // Complete GC closure
4137 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4138
4139 // Call the reference processing task's work routine.
4140 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4141
4142 // Note we cannot assert that the refs array is empty here as not all
4143 // of the processing tasks (specifically phase2 - pp2_work) execute
4144 // the complete_gc closure (which ordinarily would drain the queue) so
4145 // the queue may not be empty.
4146 }
4147 };
4148
4149 // Driver routine for parallel reference processing.
4150 // Creates an instance of the ref processing gang
4151 // task and has the worker threads execute it.
4152 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4153 assert(_workers != NULL, "Need parallel worker threads.");
4154
4155 ParallelTaskTerminator terminator(_active_workers, _queues);
4156 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4157
4158 _workers->run_task(&proc_task_proxy);
4159 }
4160
4161 // Gang task for parallel reference enqueueing.
4162
4163 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4164 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4165 EnqueueTask& _enq_task;
4166
4167 public:
4168 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4169 AbstractGangTask("Enqueue reference objects in parallel"),
4170 _enq_task(enq_task)
4171 { }
4172
4173 virtual void work(uint worker_id) {
4174 _enq_task.work(worker_id);
4175 }
4176 };
4177
4178 // Driver routine for parallel reference enqueueing.
4179 // Creates an instance of the ref enqueueing gang
4180 // task and has the worker threads execute it.
4181
4182 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4183 assert(_workers != NULL, "Need parallel worker threads.");
4184
4185 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4186
4187 _workers->run_task(&enq_task_proxy);
4188 }
4189
4190 // End of weak reference support closures
4191
4192 // Abstract task used to preserve (i.e. copy) any referent objects
4193 // that are in the collection set and are pointed to by reference
4194 // objects discovered by the CM ref processor.
4195
4196 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4197 protected:
4198 G1CollectedHeap* _g1h;
4199 G1ParScanThreadStateSet* _pss;
4200 RefToScanQueueSet* _queues;
4201 ParallelTaskTerminator _terminator;
4202 uint _n_workers;
4203
4204 public:
4205 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4206 AbstractGangTask("ParPreserveCMReferents"),
4207 _g1h(g1h),
4208 _pss(per_thread_states),
4209 _queues(task_queues),
4210 _terminator(workers, _queues),
4211 _n_workers(workers)
4212 {
4213 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4214 }
4215
4216 void work(uint worker_id) {
4217 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4218
4219 ResourceMark rm;
4220 HandleMark hm;
4221
4222 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4223 pss->set_ref_processor(NULL);
4224 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4225
4226 // Is alive closure
4227 G1AlwaysAliveClosure always_alive(_g1h);
4228
4229 // Copying keep alive closure. Applied to referent objects that need
4230 // to be copied.
4231 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4232
4233 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4234
4235 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4236 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4237
4238 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4239 // So this must be true - but assert just in case someone decides to
4240 // change the worker ids.
4241 assert(worker_id < limit, "sanity");
4242 assert(!rp->discovery_is_atomic(), "check this code");
4243
4244 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4245 for (uint idx = worker_id; idx < limit; idx += stride) {
4246 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4247
4248 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4249 while (iter.has_next()) {
4250 // Since discovery is not atomic for the CM ref processor, we
4251 // can see some null referent objects.
4252 iter.load_ptrs(DEBUG_ONLY(true));
4253 oop ref = iter.obj();
4254
4255 // This will filter nulls.
4256 if (iter.is_referent_alive()) {
4257 iter.make_referent_alive();
4258 }
4259 iter.move_to_next();
4260 }
4261 }
4262
4263 // Drain the queue - which may cause stealing
4264 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4265 drain_queue.do_void();
4266 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4267 assert(pss->queue_is_empty(), "should be");
4268 }
4269 };
4270
4271 void G1CollectedHeap::process_weak_jni_handles() {
4272 double ref_proc_start = os::elapsedTime();
4273
4274 G1STWIsAliveClosure is_alive(this);
4275 G1KeepAliveClosure keep_alive(this);
4276 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4277
4278 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4279 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4280 }
4281
4282 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4283 // Any reference objects, in the collection set, that were 'discovered'
4284 // by the CM ref processor should have already been copied (either by
4285 // applying the external root copy closure to the discovered lists, or
4286 // by following an RSet entry).
4287 //
4288 // But some of the referents, that are in the collection set, that these
4289 // reference objects point to may not have been copied: the STW ref
4290 // processor would have seen that the reference object had already
4291 // been 'discovered' and would have skipped discovering the reference,
4292 // but would not have treated the reference object as a regular oop.
4293 // As a result the copy closure would not have been applied to the
4294 // referent object.
4295 //
4296 // We need to explicitly copy these referent objects - the references
4297 // will be processed at the end of remarking.
4298 //
4299 // We also need to do this copying before we process the reference
4300 // objects discovered by the STW ref processor in case one of these
4301 // referents points to another object which is also referenced by an
4302 // object discovered by the STW ref processor.
4303 double preserve_cm_referents_time = 0.0;
4304
4305 // To avoid spawning task when there is no work to do, check that
4306 // a concurrent cycle is active and that some references have been
4307 // discovered.
4308 if (concurrent_mark()->cmThread()->during_cycle() &&
4309 ref_processor_cm()->has_discovered_references()) {
4310 double preserve_cm_referents_start = os::elapsedTime();
4311 uint no_of_gc_workers = workers()->active_workers();
4312 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4313 per_thread_states,
4314 no_of_gc_workers,
4315 _task_queues);
4316 workers()->run_task(&keep_cm_referents);
4317 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4318 }
4319
4320 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4321 }
4322
4323 // Weak Reference processing during an evacuation pause (part 1).
4324 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4325 double ref_proc_start = os::elapsedTime();
4326
4327 ReferenceProcessor* rp = _ref_processor_stw;
4328 assert(rp->discovery_enabled(), "should have been enabled");
4329
4330 // Closure to test whether a referent is alive.
4331 G1STWIsAliveClosure is_alive(this);
4332
4333 // Even when parallel reference processing is enabled, the processing
4334 // of JNI refs is serial and performed serially by the current thread
4335 // rather than by a worker. The following PSS will be used for processing
4336 // JNI refs.
4337
4338 // Use only a single queue for this PSS.
4339 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4340 pss->set_ref_processor(NULL);
4341 assert(pss->queue_is_empty(), "pre-condition");
4342
4343 // Keep alive closure.
4344 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4345
4346 // Serial Complete GC closure
4347 G1STWDrainQueueClosure drain_queue(this, pss);
4348
4349 // Setup the soft refs policy...
4350 rp->setup_policy(false);
4351
4352 ReferenceProcessorStats stats;
4353 if (!rp->processing_is_mt()) {
4354 // Serial reference processing...
4355 stats = rp->process_discovered_references(&is_alive,
4356 &keep_alive,
4357 &drain_queue,
4358 NULL,
4359 _gc_timer_stw);
4360 } else {
4361 uint no_of_gc_workers = workers()->active_workers();
4362
4363 // Parallel reference processing
4364 assert(no_of_gc_workers <= rp->max_num_q(),
4365 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4366 no_of_gc_workers, rp->max_num_q());
4367
4368 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4369 stats = rp->process_discovered_references(&is_alive,
4370 &keep_alive,
4371 &drain_queue,
4372 &par_task_executor,
4373 _gc_timer_stw);
4374 }
4375
4376 _gc_tracer_stw->report_gc_reference_stats(stats);
4377
4378 // We have completed copying any necessary live referent objects.
4379 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4380
4381 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4382 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4383 }
4384
4385 // Weak Reference processing during an evacuation pause (part 2).
4386 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4387 double ref_enq_start = os::elapsedTime();
4388
4389 ReferenceProcessor* rp = _ref_processor_stw;
4390 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4391
4392 // Now enqueue any remaining on the discovered lists on to
4393 // the pending list.
4394 if (!rp->processing_is_mt()) {
4395 // Serial reference processing...
4396 rp->enqueue_discovered_references();
4397 } else {
4398 // Parallel reference enqueueing
4399
4400 uint n_workers = workers()->active_workers();
4401
4402 assert(n_workers <= rp->max_num_q(),
4403 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4404 n_workers, rp->max_num_q());
4405
4406 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4407 rp->enqueue_discovered_references(&par_task_executor);
4408 }
4409
4410 rp->verify_no_references_recorded();
4411 assert(!rp->discovery_enabled(), "should have been disabled");
4412
4413 // FIXME
4414 // CM's reference processing also cleans up the string and symbol tables.
4415 // Should we do that here also? We could, but it is a serial operation
4416 // and could significantly increase the pause time.
4417
4418 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4419 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4420 }
4421
4422 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4423 double merge_pss_time_start = os::elapsedTime();
4424 per_thread_states->flush();
4425 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4426 }
4427
4428 void G1CollectedHeap::pre_evacuate_collection_set() {
4429 _expand_heap_after_alloc_failure = true;
4430 _evacuation_failed = false;
4431
4432 // Disable the hot card cache.
4433 _hot_card_cache->reset_hot_cache_claimed_index();
4434 _hot_card_cache->set_use_cache(false);
4435
4436 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4437 _preserved_marks_set.assert_empty();
4438
4439 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4440
4441 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4442 if (collector_state()->during_initial_mark_pause()) {
4443 double start_clear_claimed_marks = os::elapsedTime();
4444
4445 ClassLoaderDataGraph::clear_claimed_marks();
4446
4447 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4448 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4449 }
4450 }
4451
4452 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4453 // Should G1EvacuationFailureALot be in effect for this GC?
4454 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4455
4456 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4457
4458 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4459
4460 double start_par_time_sec = os::elapsedTime();
4461 double end_par_time_sec;
4462
4463 {
4464 const uint n_workers = workers()->active_workers();
4465 G1RootProcessor root_processor(this, n_workers);
4466 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4467
4468 print_termination_stats_hdr();
4469
4470 workers()->run_task(&g1_par_task);
4471 end_par_time_sec = os::elapsedTime();
4472
4473 // Closing the inner scope will execute the destructor
4474 // for the G1RootProcessor object. We record the current
4475 // elapsed time before closing the scope so that time
4476 // taken for the destructor is NOT included in the
4477 // reported parallel time.
4478 }
4479
4480 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4481 phase_times->record_par_time(par_time_ms);
4482
4483 double code_root_fixup_time_ms =
4484 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4485 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4486 }
4487
4488 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4489 // Process any discovered reference objects - we have
4490 // to do this _before_ we retire the GC alloc regions
4491 // as we may have to copy some 'reachable' referent
4492 // objects (and their reachable sub-graphs) that were
4493 // not copied during the pause.
4494 if (g1_policy()->should_process_references()) {
4495 preserve_cm_referents(per_thread_states);
4496 process_discovered_references(per_thread_states);
4497 } else {
4498 ref_processor_stw()->verify_no_references_recorded();
4499 process_weak_jni_handles();
4500 }
4501
4502 if (G1StringDedup::is_enabled()) {
4503 double fixup_start = os::elapsedTime();
4504
4505 G1STWIsAliveClosure is_alive(this);
4506 G1KeepAliveClosure keep_alive(this);
4507 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4508
4509 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4510 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4511 }
4512
4513 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4514
4515 if (evacuation_failed()) {
4516 restore_after_evac_failure();
4517
4518 // Reset the G1EvacuationFailureALot counters and flags
4519 // Note: the values are reset only when an actual
4520 // evacuation failure occurs.
4521 NOT_PRODUCT(reset_evacuation_should_fail();)
4522 }
4523
4524 _preserved_marks_set.assert_empty();
4525
4526 // Enqueue any remaining references remaining on the STW
4527 // reference processor's discovered lists. We need to do
4528 // this after the card table is cleaned (and verified) as
4529 // the act of enqueueing entries on to the pending list
4530 // will log these updates (and dirty their associated
4531 // cards). We need these updates logged to update any
4532 // RSets.
4533 if (g1_policy()->should_process_references()) {
4534 enqueue_discovered_references(per_thread_states);
4535 } else {
4536 g1_policy()->phase_times()->record_ref_enq_time(0);
4537 }
4538
4539 _allocator->release_gc_alloc_regions(evacuation_info);
4540
4541 merge_per_thread_state_info(per_thread_states);
4542
4543 // Reset and re-enable the hot card cache.
4544 // Note the counts for the cards in the regions in the
4545 // collection set are reset when the collection set is freed.
4546 _hot_card_cache->reset_hot_cache();
4547 _hot_card_cache->set_use_cache(true);
4548
4549 purge_code_root_memory();
4550
4551 redirty_logged_cards();
4552 #if defined(COMPILER2) || INCLUDE_JVMCI
4553 double start = os::elapsedTime();
4554 DerivedPointerTable::update_pointers();
4555 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4556 #endif
4557 g1_policy()->print_age_table();
4558 }
4559
4560 void G1CollectedHeap::record_obj_copy_mem_stats() {
4561 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4562
4563 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4564 create_g1_evac_summary(&_old_evac_stats));
4565 }
4566
4567 void G1CollectedHeap::free_region(HeapRegion* hr,
4568 FreeRegionList* free_list,
4569 bool skip_remset,
4570 bool skip_hot_card_cache,
4571 bool locked) {
4572 assert(!hr->is_free(), "the region should not be free");
4573 assert(!hr->is_empty(), "the region should not be empty");
4574 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4575 assert(free_list != NULL, "pre-condition");
4576
4577 if (G1VerifyBitmaps) {
4578 MemRegion mr(hr->bottom(), hr->end());
4579 concurrent_mark()->clearRangePrevBitmap(mr);
4580 }
4581
4582 // Clear the card counts for this region.
4583 // Note: we only need to do this if the region is not young
4584 // (since we don't refine cards in young regions).
4585 if (!skip_hot_card_cache && !hr->is_young()) {
4586 _hot_card_cache->reset_card_counts(hr);
4587 }
4588 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4589 free_list->add_ordered(hr);
4590 }
4591
4592 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4593 FreeRegionList* free_list,
4594 bool skip_remset) {
4595 assert(hr->is_humongous(), "this is only for humongous regions");
4596 assert(free_list != NULL, "pre-condition");
4597 hr->clear_humongous();
4598 free_region(hr, free_list, skip_remset);
4599 }
4600
4601 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4602 const uint humongous_regions_removed) {
4603 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4604 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4605 _old_set.bulk_remove(old_regions_removed);
4606 _humongous_set.bulk_remove(humongous_regions_removed);
4607 }
4608
4609 }
4610
4611 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4612 assert(list != NULL, "list can't be null");
4613 if (!list->is_empty()) {
4614 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4615 _hrm.insert_list_into_free_list(list);
4616 }
4617 }
4618
4619 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4620 decrease_used(bytes);
4621 }
4622
4623 class G1ParScrubRemSetTask: public AbstractGangTask {
4624 protected:
4625 G1RemSet* _g1rs;
4626 HeapRegionClaimer _hrclaimer;
4627
4628 public:
4629 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4630 AbstractGangTask("G1 ScrubRS"),
4631 _g1rs(g1_rs),
4632 _hrclaimer(num_workers) {
4633 }
4634
4635 void work(uint worker_id) {
4636 _g1rs->scrub(worker_id, &_hrclaimer);
4637 }
4638 };
4639
4640 void G1CollectedHeap::scrub_rem_set() {
4641 uint num_workers = workers()->active_workers();
4642 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4643 workers()->run_task(&g1_par_scrub_rs_task);
4644 }
4645
4646 class G1FreeCollectionSetTask : public AbstractGangTask {
4647 private:
4648
4649 // Closure applied to all regions in the collection set to do work that needs to
4650 // be done serially in a single thread.
4651 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4652 private:
4653 EvacuationInfo* _evacuation_info;
4654 const size_t* _surviving_young_words;
4655
4656 // Bytes used in successfully evacuated regions before the evacuation.
4657 size_t _before_used_bytes;
4658 // Bytes used in unsucessfully evacuated regions before the evacuation
4659 size_t _after_used_bytes;
4660
4661 size_t _bytes_allocated_in_old_since_last_gc;
4662
4663 size_t _failure_used_words;
4664 size_t _failure_waste_words;
4665
4666 FreeRegionList _local_free_list;
4667 public:
4668 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4669 HeapRegionClosure(),
4670 _evacuation_info(evacuation_info),
4671 _surviving_young_words(surviving_young_words),
4672 _before_used_bytes(0),
4673 _after_used_bytes(0),
4674 _bytes_allocated_in_old_since_last_gc(0),
4675 _failure_used_words(0),
4676 _failure_waste_words(0),
4677 _local_free_list("Local Region List for CSet Freeing") {
4678 }
4679
4680 virtual bool doHeapRegion(HeapRegion* r) {
4681 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4682
4683 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4684 g1h->clear_in_cset(r);
4685
4686 if (r->is_young()) {
4687 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4688 "Young index %d is wrong for region %u of type %s with %u young regions",
4689 r->young_index_in_cset(),
4690 r->hrm_index(),
4691 r->get_type_str(),
4692 g1h->collection_set()->young_region_length());
4693 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4694 r->record_surv_words_in_group(words_survived);
4695 }
4696
4697 if (!r->evacuation_failed()) {
4698 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4699 _before_used_bytes += r->used();
4700 g1h->free_region(r,
4701 &_local_free_list,
4702 true, /* skip_remset */
4703 true, /* skip_hot_card_cache */
4704 true /* locked */);
4705 } else {
4706 r->uninstall_surv_rate_group();
4707 r->set_young_index_in_cset(-1);
4708 r->set_evacuation_failed(false);
4709 // When moving a young gen region to old gen, we "allocate" that whole region
4710 // there. This is in addition to any already evacuated objects. Notify the
4711 // policy about that.
4712 // Old gen regions do not cause an additional allocation: both the objects
4713 // still in the region and the ones already moved are accounted for elsewhere.
4714 if (r->is_young()) {
4715 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4716 }
4717 // The region is now considered to be old.
4718 r->set_old();
4719 // Do some allocation statistics accounting. Regions that failed evacuation
4720 // are always made old, so there is no need to update anything in the young
4721 // gen statistics, but we need to update old gen statistics.
4722 size_t used_words = r->marked_bytes() / HeapWordSize;
4723
4724 _failure_used_words += used_words;
4725 _failure_waste_words += HeapRegion::GrainWords - used_words;
4726
4727 g1h->old_set_add(r);
4728 _after_used_bytes += r->used();
4729 }
4730 return false;
4731 }
4732
4733 void complete_work() {
4734 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4735
4736 _evacuation_info->set_regions_freed(_local_free_list.length());
4737 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4738
4739 g1h->prepend_to_freelist(&_local_free_list);
4740 g1h->decrement_summary_bytes(_before_used_bytes);
4741
4742 G1Policy* policy = g1h->g1_policy();
4743 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4744
4745 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4746 }
4747 };
4748
4749 G1CollectionSet* _collection_set;
4750 G1SerialFreeCollectionSetClosure _cl;
4751 const size_t* _surviving_young_words;
4752
4753 size_t _rs_lengths;
4754
4755 volatile jint _serial_work_claim;
4756
4757 struct WorkItem {
4758 uint region_idx;
4759 bool is_young;
4760 bool evacuation_failed;
4761
4762 WorkItem(HeapRegion* r) {
4763 region_idx = r->hrm_index();
4764 is_young = r->is_young();
4765 evacuation_failed = r->evacuation_failed();
4766 }
4767 };
4768
4769 volatile size_t _parallel_work_claim;
4770 size_t _num_work_items;
4771 WorkItem* _work_items;
4772
4773 void do_serial_work() {
4774 // Need to grab the lock to be allowed to modify the old region list.
4775 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4776 _collection_set->iterate(&_cl);
4777 }
4778
4779 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4780 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4781
4782 HeapRegion* r = g1h->region_at(region_idx);
4783 assert(!g1h->is_on_master_free_list(r), "sanity");
4784
4785 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4786
4787 if (!is_young) {
4788 g1h->_hot_card_cache->reset_card_counts(r);
4789 }
4790
4791 if (!evacuation_failed) {
4792 r->rem_set()->clear_locked();
4793 }
4794 }
4795
4796 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4797 private:
4798 size_t _cur_idx;
4799 WorkItem* _work_items;
4800 public:
4801 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4802
4803 virtual bool doHeapRegion(HeapRegion* r) {
4804 _work_items[_cur_idx++] = WorkItem(r);
4805 return false;
4806 }
4807 };
4808
4809 void prepare_work() {
4810 G1PrepareFreeCollectionSetClosure cl(_work_items);
4811 _collection_set->iterate(&cl);
4812 }
4813
4814 void complete_work() {
4815 _cl.complete_work();
4816
4817 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4818 policy->record_max_rs_lengths(_rs_lengths);
4819 policy->cset_regions_freed();
4820 }
4821 public:
4822 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4823 AbstractGangTask("G1 Free Collection Set"),
4824 _cl(evacuation_info, surviving_young_words),
4825 _collection_set(collection_set),
4826 _surviving_young_words(surviving_young_words),
4827 _serial_work_claim(0),
4828 _rs_lengths(0),
4829 _parallel_work_claim(0),
4830 _num_work_items(collection_set->region_length()),
4831 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4832 prepare_work();
4833 }
4834
4835 ~G1FreeCollectionSetTask() {
4836 complete_work();
4837 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4838 }
4839
4840 // Chunk size for work distribution. The chosen value has been determined experimentally
4841 // to be a good tradeoff between overhead and achievable parallelism.
4842 static uint chunk_size() { return 32; }
4843
4844 virtual void work(uint worker_id) {
4845 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4846
4847 // Claim serial work.
4848 if (_serial_work_claim == 0) {
4849 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4850 if (value == 0) {
4851 double serial_time = os::elapsedTime();
4852 do_serial_work();
4853 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4854 }
4855 }
4856
4857 // Start parallel work.
4858 double young_time = 0.0;
4859 bool has_young_time = false;
4860 double non_young_time = 0.0;
4861 bool has_non_young_time = false;
4862
4863 while (true) {
4864 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4865 size_t cur = end - chunk_size();
4866
4867 if (cur >= _num_work_items) {
4868 break;
4869 }
4870
4871 double start_time = os::elapsedTime();
4872
4873 end = MIN2(end, _num_work_items);
4874
4875 for (; cur < end; cur++) {
4876 bool is_young = _work_items[cur].is_young;
4877
4878 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4879
4880 double end_time = os::elapsedTime();
4881 double time_taken = end_time - start_time;
4882 if (is_young) {
4883 young_time += time_taken;
4884 has_young_time = true;
4885 } else {
4886 non_young_time += time_taken;
4887 has_non_young_time = true;
4888 }
4889 start_time = end_time;
4890 }
4891 }
4892
4893 if (has_young_time) {
4894 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4895 }
4896 if (has_non_young_time) {
4897 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4898 }
4899 }
4900 };
4901
4902 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4903 _eden.clear();
4904
4905 double free_cset_start_time = os::elapsedTime();
4906
4907 {
4908 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4909 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4910
4911 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4912
4913 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4914 cl.name(),
4915 num_workers,
4916 _collection_set.region_length());
4917 workers()->run_task(&cl, num_workers);
4918 }
4919 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4920
4921 collection_set->clear();
4922 }
4923
4924 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4925 private:
4926 FreeRegionList* _free_region_list;
4927 HeapRegionSet* _proxy_set;
4928 uint _humongous_objects_reclaimed;
4929 uint _humongous_regions_reclaimed;
4930 size_t _freed_bytes;
4931 public:
4932
4933 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4934 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4935 }
4936
4937 virtual bool doHeapRegion(HeapRegion* r) {
4938 if (!r->is_starts_humongous()) {
4939 return false;
4940 }
4941
4942 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4943
4944 oop obj = (oop)r->bottom();
4945 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4946
4947 // The following checks whether the humongous object is live are sufficient.
4948 // The main additional check (in addition to having a reference from the roots
4949 // or the young gen) is whether the humongous object has a remembered set entry.
4950 //
4951 // A humongous object cannot be live if there is no remembered set for it
4952 // because:
4953 // - there can be no references from within humongous starts regions referencing
4954 // the object because we never allocate other objects into them.
4955 // (I.e. there are no intra-region references that may be missed by the
4956 // remembered set)
4957 // - as soon there is a remembered set entry to the humongous starts region
4958 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4959 // until the end of a concurrent mark.
4960 //
4961 // It is not required to check whether the object has been found dead by marking
4962 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4963 // all objects allocated during that time are considered live.
4964 // SATB marking is even more conservative than the remembered set.
4965 // So if at this point in the collection there is no remembered set entry,
4966 // nobody has a reference to it.
4967 // At the start of collection we flush all refinement logs, and remembered sets
4968 // are completely up-to-date wrt to references to the humongous object.
4969 //
4970 // Other implementation considerations:
4971 // - never consider object arrays at this time because they would pose
4972 // considerable effort for cleaning up the the remembered sets. This is
4973 // required because stale remembered sets might reference locations that
4974 // are currently allocated into.
4975 uint region_idx = r->hrm_index();
4976 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4977 !r->rem_set()->is_empty()) {
4978 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4979 region_idx,
4980 (size_t)obj->size() * HeapWordSize,
4981 p2i(r->bottom()),
4982 r->rem_set()->occupied(),
4983 r->rem_set()->strong_code_roots_list_length(),
4984 next_bitmap->isMarked(r->bottom()),
4985 g1h->is_humongous_reclaim_candidate(region_idx),
4986 obj->is_typeArray()
4987 );
4988 return false;
4989 }
4990
4991 guarantee(obj->is_typeArray(),
4992 "Only eagerly reclaiming type arrays is supported, but the object "
4993 PTR_FORMAT " is not.", p2i(r->bottom()));
4994
4995 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
4996 region_idx,
4997 (size_t)obj->size() * HeapWordSize,
4998 p2i(r->bottom()),
4999 r->rem_set()->occupied(),
5000 r->rem_set()->strong_code_roots_list_length(),
5001 next_bitmap->isMarked(r->bottom()),
5002 g1h->is_humongous_reclaim_candidate(region_idx),
5003 obj->is_typeArray()
5004 );
5005
5006 // Need to clear mark bit of the humongous object if already set.
5007 if (next_bitmap->isMarked(r->bottom())) {
5008 next_bitmap->clear(r->bottom());
5009 }
5010 _humongous_objects_reclaimed++;
5011 do {
5012 HeapRegion* next = g1h->next_region_in_humongous(r);
5013 _freed_bytes += r->used();
5014 r->set_containing_set(NULL);
5015 _humongous_regions_reclaimed++;
5016 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
5017 r = next;
5018 } while (r != NULL);
5019
5020 return false;
5021 }
5022
5023 uint humongous_objects_reclaimed() {
5024 return _humongous_objects_reclaimed;
5025 }
5026
5027 uint humongous_regions_reclaimed() {
5028 return _humongous_regions_reclaimed;
5029 }
5030
5031 size_t bytes_freed() const {
5032 return _freed_bytes;
5033 }
5034 };
5035
5036 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5037 assert_at_safepoint(true);
5038
5039 if (!G1EagerReclaimHumongousObjects ||
5040 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5041 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5042 return;
5043 }
5044
5045 double start_time = os::elapsedTime();
5046
5047 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5048
5049 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5050 heap_region_iterate(&cl);
5051
5052 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
5053
5054 G1HRPrinter* hrp = hr_printer();
5055 if (hrp->is_active()) {
5056 FreeRegionListIterator iter(&local_cleanup_list);
5057 while (iter.more_available()) {
5058 HeapRegion* hr = iter.get_next();
5059 hrp->cleanup(hr);
5060 }
5061 }
5062
5063 prepend_to_freelist(&local_cleanup_list);
5064 decrement_summary_bytes(cl.bytes_freed());
5065
5066 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5067 cl.humongous_objects_reclaimed());
5068 }
5069
5070 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5071 public:
5072 virtual bool doHeapRegion(HeapRegion* r) {
5073 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5074 G1CollectedHeap::heap()->clear_in_cset(r);
5075 r->set_young_index_in_cset(-1);
5076 return false;
5077 }
5078 };
5079
5080 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5081 G1AbandonCollectionSetClosure cl;
5082 collection_set->iterate(&cl);
5083
5084 collection_set->clear();
5085 collection_set->stop_incremental_building();
5086 }
5087
5088 void G1CollectedHeap::set_free_regions_coming() {
5089 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5090
5091 assert(!free_regions_coming(), "pre-condition");
5092 _free_regions_coming = true;
5093 }
5094
5095 void G1CollectedHeap::reset_free_regions_coming() {
5096 assert(free_regions_coming(), "pre-condition");
5097
5098 {
5099 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5100 _free_regions_coming = false;
5101 SecondaryFreeList_lock->notify_all();
5102 }
5103
5104 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5105 }
5106
5107 void G1CollectedHeap::wait_while_free_regions_coming() {
5108 // Most of the time we won't have to wait, so let's do a quick test
5109 // first before we take the lock.
5110 if (!free_regions_coming()) {
5111 return;
5112 }
5113
5114 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5115
5116 {
5117 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5118 while (free_regions_coming()) {
5119 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5120 }
5121 }
5122
5123 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5124 }
5125
5126 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5127 return _allocator->is_retained_old_region(hr);
5128 }
5129
5130 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5131 _eden.add(hr);
5132 _g1_policy->set_region_eden(hr);
5133 }
5134
5135 #ifdef ASSERT
5136
5137 class NoYoungRegionsClosure: public HeapRegionClosure {
5138 private:
5139 bool _success;
5140 public:
5141 NoYoungRegionsClosure() : _success(true) { }
5142 bool doHeapRegion(HeapRegion* r) {
5143 if (r->is_young()) {
5144 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5145 p2i(r->bottom()), p2i(r->end()));
5146 _success = false;
5147 }
5148 return false;
5149 }
5150 bool success() { return _success; }
5151 };
5152
5153 bool G1CollectedHeap::check_young_list_empty() {
5154 bool ret = (young_regions_count() == 0);
5155
5156 NoYoungRegionsClosure closure;
5157 heap_region_iterate(&closure);
5158 ret = ret && closure.success();
5159
5160 return ret;
5161 }
5162
5163 #endif // ASSERT
5164
5165 class TearDownRegionSetsClosure : public HeapRegionClosure {
5166 private:
5167 HeapRegionSet *_old_set;
5168
5169 public:
5170 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5171
5172 bool doHeapRegion(HeapRegion* r) {
5173 if (r->is_old()) {
5174 _old_set->remove(r);
5175 } else if(r->is_young()) {
5176 r->uninstall_surv_rate_group();
5177 } else {
5178 // We ignore free regions, we'll empty the free list afterwards.
5179 // We ignore humongous regions, we're not tearing down the
5180 // humongous regions set.
5181 assert(r->is_free() || r->is_humongous(),
5182 "it cannot be another type");
5183 }
5184 return false;
5185 }
5186
5187 ~TearDownRegionSetsClosure() {
5188 assert(_old_set->is_empty(), "post-condition");
5189 }
5190 };
5191
5192 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5193 assert_at_safepoint(true /* should_be_vm_thread */);
5194
5195 if (!free_list_only) {
5196 TearDownRegionSetsClosure cl(&_old_set);
5197 heap_region_iterate(&cl);
5198
5199 // Note that emptying the _young_list is postponed and instead done as
5200 // the first step when rebuilding the regions sets again. The reason for
5201 // this is that during a full GC string deduplication needs to know if
5202 // a collected region was young or old when the full GC was initiated.
5203 }
5204 _hrm.remove_all_free_regions();
5205 }
5206
5207 void G1CollectedHeap::increase_used(size_t bytes) {
5208 _summary_bytes_used += bytes;
5209 }
5210
5211 void G1CollectedHeap::decrease_used(size_t bytes) {
5212 assert(_summary_bytes_used >= bytes,
5213 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5214 _summary_bytes_used, bytes);
5215 _summary_bytes_used -= bytes;
5216 }
5217
5218 void G1CollectedHeap::set_used(size_t bytes) {
5219 _summary_bytes_used = bytes;
5220 }
5221
5222 class RebuildRegionSetsClosure : public HeapRegionClosure {
5223 private:
5224 bool _free_list_only;
5225 HeapRegionSet* _old_set;
5226 HeapRegionManager* _hrm;
5227 size_t _total_used;
5228
5229 public:
5230 RebuildRegionSetsClosure(bool free_list_only,
5231 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5232 _free_list_only(free_list_only),
5233 _old_set(old_set), _hrm(hrm), _total_used(0) {
5234 assert(_hrm->num_free_regions() == 0, "pre-condition");
5235 if (!free_list_only) {
5236 assert(_old_set->is_empty(), "pre-condition");
5237 }
5238 }
5239
5240 bool doHeapRegion(HeapRegion* r) {
5241 if (r->is_empty()) {
5242 // Add free regions to the free list
5243 r->set_free();
5244 r->set_allocation_context(AllocationContext::system());
5245 _hrm->insert_into_free_list(r);
5246 } else if (!_free_list_only) {
5247
5248 if (r->is_humongous()) {
5249 // We ignore humongous regions. We left the humongous set unchanged.
5250 } else {
5251 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5252 // We now consider all regions old, so register as such. Leave
5253 // archive regions set that way, however, while still adding
5254 // them to the old set.
5255 if (!r->is_archive()) {
5256 r->set_old();
5257 }
5258 _old_set->add(r);
5259 }
5260 _total_used += r->used();
5261 }
5262
5263 return false;
5264 }
5265
5266 size_t total_used() {
5267 return _total_used;
5268 }
5269 };
5270
5271 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5272 assert_at_safepoint(true /* should_be_vm_thread */);
5273
5274 if (!free_list_only) {
5275 _eden.clear();
5276 _survivor.clear();
5277 }
5278
5279 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5280 heap_region_iterate(&cl);
5281
5282 if (!free_list_only) {
5283 set_used(cl.total_used());
5284 if (_archive_allocator != NULL) {
5285 _archive_allocator->clear_used();
5286 }
5287 }
5288 assert(used_unlocked() == recalculate_used(),
5289 "inconsistent used_unlocked(), "
5290 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5291 used_unlocked(), recalculate_used());
5292 }
5293
5294 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5295 _refine_cte_cl->set_concurrent(concurrent);
5296 }
5297
5298 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5299 HeapRegion* hr = heap_region_containing(p);
5300 return hr->is_in(p);
5301 }
5302
5303 // Methods for the mutator alloc region
5304
5305 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5306 bool force) {
5307 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5308 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5309 if (force || should_allocate) {
5310 HeapRegion* new_alloc_region = new_region(word_size,
5311 false /* is_old */,
5312 false /* do_expand */);
5313 if (new_alloc_region != NULL) {
5314 set_region_short_lived_locked(new_alloc_region);
5315 _hr_printer.alloc(new_alloc_region, !should_allocate);
5316 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5317 return new_alloc_region;
5318 }
5319 }
5320 return NULL;
5321 }
5322
5323 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5324 size_t allocated_bytes) {
5325 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5326 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5327
5328 collection_set()->add_eden_region(alloc_region);
5329 increase_used(allocated_bytes);
5330 _hr_printer.retire(alloc_region);
5331 // We update the eden sizes here, when the region is retired,
5332 // instead of when it's allocated, since this is the point that its
5333 // used space has been recored in _summary_bytes_used.
5334 g1mm()->update_eden_size();
5335 }
5336
5337 // Methods for the GC alloc regions
5338
5339 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5340 if (dest.is_old()) {
5341 return true;
5342 } else {
5343 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5344 }
5345 }
5346
5347 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5348 assert(FreeList_lock->owned_by_self(), "pre-condition");
5349
5350 if (!has_more_regions(dest)) {
5351 return NULL;
5352 }
5353
5354 const bool is_survivor = dest.is_young();
5355
5356 HeapRegion* new_alloc_region = new_region(word_size,
5357 !is_survivor,
5358 true /* do_expand */);
5359 if (new_alloc_region != NULL) {
5360 // We really only need to do this for old regions given that we
5361 // should never scan survivors. But it doesn't hurt to do it
5362 // for survivors too.
5363 new_alloc_region->record_timestamp();
5364 if (is_survivor) {
5365 new_alloc_region->set_survivor();
5366 _survivor.add(new_alloc_region);
5367 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5368 } else {
5369 new_alloc_region->set_old();
5370 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5371 }
5372 _hr_printer.alloc(new_alloc_region);
5373 bool during_im = collector_state()->during_initial_mark_pause();
5374 new_alloc_region->note_start_of_copying(during_im);
5375 return new_alloc_region;
5376 }
5377 return NULL;
5378 }
5379
5380 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5381 size_t allocated_bytes,
5382 InCSetState dest) {
5383 bool during_im = collector_state()->during_initial_mark_pause();
5384 alloc_region->note_end_of_copying(during_im);
5385 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5386 if (dest.is_old()) {
5387 _old_set.add(alloc_region);
5388 }
5389 _hr_printer.retire(alloc_region);
5390 }
5391
5392 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5393 bool expanded = false;
5394 uint index = _hrm.find_highest_free(&expanded);
5395
5396 if (index != G1_NO_HRM_INDEX) {
5397 if (expanded) {
5398 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5399 HeapRegion::GrainWords * HeapWordSize);
5400 }
5401 _hrm.allocate_free_regions_starting_at(index, 1);
5402 return region_at(index);
5403 }
5404 return NULL;
5405 }
5406
5407 // Optimized nmethod scanning
5408
5409 class RegisterNMethodOopClosure: public OopClosure {
5410 G1CollectedHeap* _g1h;
5411 nmethod* _nm;
5412
5413 template <class T> void do_oop_work(T* p) {
5414 T heap_oop = oopDesc::load_heap_oop(p);
5415 if (!oopDesc::is_null(heap_oop)) {
5416 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5417 HeapRegion* hr = _g1h->heap_region_containing(obj);
5418 assert(!hr->is_continues_humongous(),
5419 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5420 " starting at " HR_FORMAT,
5421 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5422
5423 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5424 hr->add_strong_code_root_locked(_nm);
5425 }
5426 }
5427
5428 public:
5429 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5430 _g1h(g1h), _nm(nm) {}
5431
5432 void do_oop(oop* p) { do_oop_work(p); }
5433 void do_oop(narrowOop* p) { do_oop_work(p); }
5434 };
5435
5436 class UnregisterNMethodOopClosure: public OopClosure {
5437 G1CollectedHeap* _g1h;
5438 nmethod* _nm;
5439
5440 template <class T> void do_oop_work(T* p) {
5441 T heap_oop = oopDesc::load_heap_oop(p);
5442 if (!oopDesc::is_null(heap_oop)) {
5443 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5444 HeapRegion* hr = _g1h->heap_region_containing(obj);
5445 assert(!hr->is_continues_humongous(),
5446 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5447 " starting at " HR_FORMAT,
5448 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5449
5450 hr->remove_strong_code_root(_nm);
5451 }
5452 }
5453
5454 public:
5455 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5456 _g1h(g1h), _nm(nm) {}
5457
5458 void do_oop(oop* p) { do_oop_work(p); }
5459 void do_oop(narrowOop* p) { do_oop_work(p); }
5460 };
5461
5462 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5463 CollectedHeap::register_nmethod(nm);
5464
5465 guarantee(nm != NULL, "sanity");
5466 RegisterNMethodOopClosure reg_cl(this, nm);
5467 nm->oops_do(®_cl);
5468 }
5469
5470 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5471 CollectedHeap::unregister_nmethod(nm);
5472
5473 guarantee(nm != NULL, "sanity");
5474 UnregisterNMethodOopClosure reg_cl(this, nm);
5475 nm->oops_do(®_cl, true);
5476 }
5477
5478 void G1CollectedHeap::purge_code_root_memory() {
5479 double purge_start = os::elapsedTime();
5480 G1CodeRootSet::purge();
5481 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5482 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5483 }
5484
5485 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5486 G1CollectedHeap* _g1h;
5487
5488 public:
5489 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5490 _g1h(g1h) {}
5491
5492 void do_code_blob(CodeBlob* cb) {
5493 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5494 if (nm == NULL) {
5495 return;
5496 }
5497
5498 if (ScavengeRootsInCode) {
5499 _g1h->register_nmethod(nm);
5500 }
5501 }
5502 };
5503
5504 void G1CollectedHeap::rebuild_strong_code_roots() {
5505 RebuildStrongCodeRootClosure blob_cl(this);
5506 CodeCache::blobs_do(&blob_cl);
5507 }