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/g1FullCollector.hpp"
42 #include "gc/g1/g1FullGCScope.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.inline.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/heapRegion.inline.hpp"
58 #include "gc/g1/heapRegionRemSet.hpp"
59 #include "gc/g1/heapRegionSet.inline.hpp"
60 #include "gc/g1/suspendibleThreadSet.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/gcHeapSummary.hpp"
63 #include "gc/shared/gcId.hpp"
64 #include "gc/shared/gcLocker.inline.hpp"
65 #include "gc/shared/gcTimer.hpp"
66 #include "gc/shared/gcTrace.hpp"
67 #include "gc/shared/gcTraceTime.inline.hpp"
68 #include "gc/shared/generationSpec.hpp"
69 #include "gc/shared/isGCActiveMark.hpp"
70 #include "gc/shared/preservedMarks.inline.hpp"
71 #include "gc/shared/referenceProcessor.inline.hpp"
72 #include "gc/shared/taskqueue.inline.hpp"
73 #include "logging/log.hpp"
74 #include "memory/allocation.hpp"
75 #include "memory/iterator.hpp"
76 #include "memory/resourceArea.hpp"
77 #include "oops/oop.inline.hpp"
78 #include "prims/resolvedMethodTable.hpp"
79 #include "runtime/atomic.hpp"
80 #include "runtime/init.hpp"
81 #include "runtime/orderAccess.inline.hpp"
82 #include "runtime/vmThread.hpp"
83 #include "utilities/align.hpp"
84 #include "utilities/globalDefinitions.hpp"
85 #include "utilities/stack.inline.hpp"
86
87 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
88
89 // INVARIANTS/NOTES
90 //
91 // All allocation activity covered by the G1CollectedHeap interface is
92 // serialized by acquiring the HeapLock. This happens in mem_allocate
93 // and allocate_new_tlab, which are the "entry" points to the
94 // allocation code from the rest of the JVM. (Note that this does not
95 // apply to TLAB allocation, which is not part of this interface: it
96 // is done by clients of this interface.)
97
98 // Local to this file.
99
100 class RefineCardTableEntryClosure: public CardTableEntryClosure {
101 bool _concurrent;
102 public:
103 RefineCardTableEntryClosure() : _concurrent(true) { }
104
105 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
106 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
107
108 if (_concurrent && SuspendibleThreadSet::should_yield()) {
109 // Caller will actually yield.
110 return false;
111 }
112 // Otherwise, we finished successfully; return true.
113 return true;
114 }
115
116 void set_concurrent(bool b) { _concurrent = b; }
117 };
118
119
120 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
121 private:
122 size_t _num_dirtied;
123 G1CollectedHeap* _g1h;
124 G1SATBCardTableLoggingModRefBS* _g1_bs;
125
126 HeapRegion* region_for_card(jbyte* card_ptr) const {
127 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
128 }
129
130 bool will_become_free(HeapRegion* hr) const {
131 // A region will be freed by free_collection_set if the region is in the
132 // collection set and has not had an evacuation failure.
133 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
134 }
135
136 public:
137 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
138 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
139
140 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
141 HeapRegion* hr = region_for_card(card_ptr);
142
143 // Should only dirty cards in regions that won't be freed.
144 if (!will_become_free(hr)) {
145 *card_ptr = CardTableModRefBS::dirty_card_val();
146 _num_dirtied++;
147 }
148
149 return true;
150 }
151
152 size_t num_dirtied() const { return _num_dirtied; }
153 };
154
155
156 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
157 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
158 }
159
160 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
161 // The from card cache is not the memory that is actually committed. So we cannot
162 // take advantage of the zero_filled parameter.
163 reset_from_card_cache(start_idx, num_regions);
164 }
165
166 // Returns true if the reference points to an object that
167 // can move in an incremental collection.
168 bool G1CollectedHeap::is_scavengable(const void* p) {
169 HeapRegion* hr = heap_region_containing(p);
170 return !hr->is_pinned();
171 }
172
173
174 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
175 MemRegion mr) {
176 return new HeapRegion(hrs_index, bot(), mr);
177 }
178
179 // Private methods.
180
181 HeapRegion*
182 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
183 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
184 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
185 if (!_secondary_free_list.is_empty()) {
186 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
187 "secondary_free_list has %u entries",
188 _secondary_free_list.length());
189 // It looks as if there are free regions available on the
190 // secondary_free_list. Let's move them to the free_list and try
191 // again to allocate from it.
192 append_secondary_free_list();
193
194 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
195 "empty we should have moved at least one entry to the free_list");
196 HeapRegion* res = _hrm.allocate_free_region(is_old);
197 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
198 "allocated " HR_FORMAT " from secondary_free_list",
199 HR_FORMAT_PARAMS(res));
200 return res;
201 }
202
203 // Wait here until we get notified either when (a) there are no
204 // more free regions coming or (b) some regions have been moved on
205 // the secondary_free_list.
206 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
207 }
208
209 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
210 "could not allocate from secondary_free_list");
211 return NULL;
212 }
213
214 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
215 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
216 "the only time we use this to allocate a humongous region is "
217 "when we are allocating a single humongous region");
218
219 HeapRegion* res;
220 if (G1StressConcRegionFreeing) {
221 if (!_secondary_free_list.is_empty()) {
222 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
223 "forced to look at the secondary_free_list");
224 res = new_region_try_secondary_free_list(is_old);
225 if (res != NULL) {
226 return res;
227 }
228 }
229 }
230
231 res = _hrm.allocate_free_region(is_old);
232
233 if (res == NULL) {
234 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
235 "res == NULL, trying the secondary_free_list");
236 res = new_region_try_secondary_free_list(is_old);
237 }
238 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
239 // Currently, only attempts to allocate GC alloc regions set
240 // do_expand to true. So, we should only reach here during a
241 // safepoint. If this assumption changes we might have to
242 // reconsider the use of _expand_heap_after_alloc_failure.
243 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
244
245 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
246 word_size * HeapWordSize);
247
248 if (expand(word_size * HeapWordSize)) {
249 // Given that expand() succeeded in expanding the heap, and we
250 // always expand the heap by an amount aligned to the heap
251 // region size, the free list should in theory not be empty.
252 // In either case allocate_free_region() will check for NULL.
253 res = _hrm.allocate_free_region(is_old);
254 } else {
255 _expand_heap_after_alloc_failure = false;
256 }
257 }
258 return res;
259 }
260
261 HeapWord*
262 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
263 uint num_regions,
264 size_t word_size,
265 AllocationContext_t context) {
266 assert(first != G1_NO_HRM_INDEX, "pre-condition");
267 assert(is_humongous(word_size), "word_size should be humongous");
268 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
269
270 // Index of last region in the series.
271 uint last = first + num_regions - 1;
272
273 // We need to initialize the region(s) we just discovered. This is
274 // a bit tricky given that it can happen concurrently with
275 // refinement threads refining cards on these regions and
276 // potentially wanting to refine the BOT as they are scanning
277 // those cards (this can happen shortly after a cleanup; see CR
278 // 6991377). So we have to set up the region(s) carefully and in
279 // a specific order.
280
281 // The word size sum of all the regions we will allocate.
282 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
283 assert(word_size <= word_size_sum, "sanity");
284
285 // This will be the "starts humongous" region.
286 HeapRegion* first_hr = region_at(first);
287 // The header of the new object will be placed at the bottom of
288 // the first region.
289 HeapWord* new_obj = first_hr->bottom();
290 // This will be the new top of the new object.
291 HeapWord* obj_top = new_obj + word_size;
292
293 // First, we need to zero the header of the space that we will be
294 // allocating. When we update top further down, some refinement
295 // threads might try to scan the region. By zeroing the header we
296 // ensure that any thread that will try to scan the region will
297 // come across the zero klass word and bail out.
298 //
299 // NOTE: It would not have been correct to have used
300 // CollectedHeap::fill_with_object() and make the space look like
301 // an int array. The thread that is doing the allocation will
302 // later update the object header to a potentially different array
303 // type and, for a very short period of time, the klass and length
304 // fields will be inconsistent. This could cause a refinement
305 // thread to calculate the object size incorrectly.
306 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
307
308 // Next, pad out the unused tail of the last region with filler
309 // objects, for improved usage accounting.
310 // How many words we use for filler objects.
311 size_t word_fill_size = word_size_sum - word_size;
312
313 // How many words memory we "waste" which cannot hold a filler object.
314 size_t words_not_fillable = 0;
315
316 if (word_fill_size >= min_fill_size()) {
317 fill_with_objects(obj_top, word_fill_size);
318 } else if (word_fill_size > 0) {
319 // We have space to fill, but we cannot fit an object there.
320 words_not_fillable = word_fill_size;
321 word_fill_size = 0;
322 }
323
324 // We will set up the first region as "starts humongous". This
325 // will also update the BOT covering all the regions to reflect
326 // that there is a single object that starts at the bottom of the
327 // first region.
328 first_hr->set_starts_humongous(obj_top, word_fill_size);
329 first_hr->set_allocation_context(context);
330 // Then, if there are any, we will set up the "continues
331 // humongous" regions.
332 HeapRegion* hr = NULL;
333 for (uint i = first + 1; i <= last; ++i) {
334 hr = region_at(i);
335 hr->set_continues_humongous(first_hr);
336 hr->set_allocation_context(context);
337 }
338
339 // Up to this point no concurrent thread would have been able to
340 // do any scanning on any region in this series. All the top
341 // fields still point to bottom, so the intersection between
342 // [bottom,top] and [card_start,card_end] will be empty. Before we
343 // update the top fields, we'll do a storestore to make sure that
344 // no thread sees the update to top before the zeroing of the
345 // object header and the BOT initialization.
346 OrderAccess::storestore();
347
348 // Now, we will update the top fields of the "continues humongous"
349 // regions except the last one.
350 for (uint i = first; i < last; ++i) {
351 hr = region_at(i);
352 hr->set_top(hr->end());
353 }
354
355 hr = region_at(last);
356 // If we cannot fit a filler object, we must set top to the end
357 // of the humongous object, otherwise we cannot iterate the heap
358 // and the BOT will not be complete.
359 hr->set_top(hr->end() - words_not_fillable);
360
361 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
362 "obj_top should be in last region");
363
364 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
365
366 assert(words_not_fillable == 0 ||
367 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
368 "Miscalculation in humongous allocation");
369
370 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
371
372 for (uint i = first; i <= last; ++i) {
373 hr = region_at(i);
374 _humongous_set.add(hr);
375 _hr_printer.alloc(hr);
376 }
377
378 return new_obj;
379 }
380
381 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
382 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
383 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
384 }
385
386 // If could fit into free regions w/o expansion, try.
387 // Otherwise, if can expand, do so.
388 // Otherwise, if using ex regions might help, try with ex given back.
389 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
390 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
391
392 _verifier->verify_region_sets_optional();
393
394 uint first = G1_NO_HRM_INDEX;
395 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
396
397 if (obj_regions == 1) {
398 // Only one region to allocate, try to use a fast path by directly allocating
399 // from the free lists. Do not try to expand here, we will potentially do that
400 // later.
401 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
402 if (hr != NULL) {
403 first = hr->hrm_index();
404 }
405 } else {
406 // We can't allocate humongous regions spanning more than one region while
407 // cleanupComplete() is running, since some of the regions we find to be
408 // empty might not yet be added to the free list. It is not straightforward
409 // to know in which list they are on so that we can remove them. We only
410 // need to do this if we need to allocate more than one region to satisfy the
411 // current humongous allocation request. If we are only allocating one region
412 // we use the one-region region allocation code (see above), that already
413 // potentially waits for regions from the secondary free list.
414 wait_while_free_regions_coming();
415 append_secondary_free_list_if_not_empty_with_lock();
416
417 // Policy: Try only empty regions (i.e. already committed first). Maybe we
418 // are lucky enough to find some.
419 first = _hrm.find_contiguous_only_empty(obj_regions);
420 if (first != G1_NO_HRM_INDEX) {
421 _hrm.allocate_free_regions_starting_at(first, obj_regions);
422 }
423 }
424
425 if (first == G1_NO_HRM_INDEX) {
426 // Policy: We could not find enough regions for the humongous object in the
427 // free list. Look through the heap to find a mix of free and uncommitted regions.
428 // If so, try expansion.
429 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
430 if (first != G1_NO_HRM_INDEX) {
431 // We found something. Make sure these regions are committed, i.e. expand
432 // the heap. Alternatively we could do a defragmentation GC.
433 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
434 word_size * HeapWordSize);
435
436 _hrm.expand_at(first, obj_regions, workers());
437 g1_policy()->record_new_heap_size(num_regions());
438
439 #ifdef ASSERT
440 for (uint i = first; i < first + obj_regions; ++i) {
441 HeapRegion* hr = region_at(i);
442 assert(hr->is_free(), "sanity");
443 assert(hr->is_empty(), "sanity");
444 assert(is_on_master_free_list(hr), "sanity");
445 }
446 #endif
447 _hrm.allocate_free_regions_starting_at(first, obj_regions);
448 } else {
449 // Policy: Potentially trigger a defragmentation GC.
450 }
451 }
452
453 HeapWord* result = NULL;
454 if (first != G1_NO_HRM_INDEX) {
455 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
456 word_size, context);
457 assert(result != NULL, "it should always return a valid result");
458
459 // A successful humongous object allocation changes the used space
460 // information of the old generation so we need to recalculate the
461 // sizes and update the jstat counters here.
462 g1mm()->update_sizes();
463 }
464
465 _verifier->verify_region_sets_optional();
466
467 return result;
468 }
469
470 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
471 assert_heap_not_locked_and_not_at_safepoint();
472 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
473
474 uint dummy_gc_count_before;
475 uint dummy_gclocker_retry_count = 0;
476 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
477 }
478
479 HeapWord*
480 G1CollectedHeap::mem_allocate(size_t word_size,
481 bool* gc_overhead_limit_was_exceeded) {
482 assert_heap_not_locked_and_not_at_safepoint();
483
484 // Loop until the allocation is satisfied, or unsatisfied after GC.
485 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
486 uint gc_count_before;
487
488 HeapWord* result = NULL;
489 if (!is_humongous(word_size)) {
490 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
491 } else {
492 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
493 }
494 if (result != NULL) {
495 return result;
496 }
497
498 // Create the garbage collection operation...
499 VM_G1CollectForAllocation op(gc_count_before, word_size);
500 op.set_allocation_context(AllocationContext::current());
501
502 // ...and get the VM thread to execute it.
503 VMThread::execute(&op);
504
505 if (op.prologue_succeeded() && op.pause_succeeded()) {
506 // If the operation was successful we'll return the result even
507 // if it is NULL. If the allocation attempt failed immediately
508 // after a Full GC, it's unlikely we'll be able to allocate now.
509 HeapWord* result = op.result();
510 if (result != NULL && !is_humongous(word_size)) {
511 // Allocations that take place on VM operations do not do any
512 // card dirtying and we have to do it here. We only have to do
513 // this for non-humongous allocations, though.
514 dirty_young_block(result, word_size);
515 }
516 return result;
517 } else {
518 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
519 return NULL;
520 }
521 assert(op.result() == NULL,
522 "the result should be NULL if the VM op did not succeed");
523 }
524
525 // Give a warning if we seem to be looping forever.
526 if ((QueuedAllocationWarningCount > 0) &&
527 (try_count % QueuedAllocationWarningCount == 0)) {
528 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
529 }
530 }
531
532 ShouldNotReachHere();
533 return NULL;
534 }
535
536 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
537 AllocationContext_t context,
538 uint* gc_count_before_ret,
539 uint* gclocker_retry_count_ret) {
540 // Make sure you read the note in attempt_allocation_humongous().
541
542 assert_heap_not_locked_and_not_at_safepoint();
543 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
544 "be called for humongous allocation requests");
545
546 // We should only get here after the first-level allocation attempt
547 // (attempt_allocation()) failed to allocate.
548
549 // We will loop until a) we manage to successfully perform the
550 // allocation or b) we successfully schedule a collection which
551 // fails to perform the allocation. b) is the only case when we'll
552 // return NULL.
553 HeapWord* result = NULL;
554 for (int try_count = 1; /* we'll return */; try_count += 1) {
555 bool should_try_gc;
556 uint gc_count_before;
557
558 {
559 MutexLockerEx x(Heap_lock);
560 result = _allocator->attempt_allocation_locked(word_size, context);
561 if (result != NULL) {
562 return result;
563 }
564
565 if (GCLocker::is_active_and_needs_gc()) {
566 if (g1_policy()->can_expand_young_list()) {
567 // No need for an ergo verbose message here,
568 // can_expand_young_list() does this when it returns true.
569 result = _allocator->attempt_allocation_force(word_size, context);
570 if (result != NULL) {
571 return result;
572 }
573 }
574 should_try_gc = false;
575 } else {
576 // The GCLocker may not be active but the GCLocker initiated
577 // GC may not yet have been performed (GCLocker::needs_gc()
578 // returns true). In this case we do not try this GC and
579 // wait until the GCLocker initiated GC is performed, and
580 // then retry the allocation.
581 if (GCLocker::needs_gc()) {
582 should_try_gc = false;
583 } else {
584 // Read the GC count while still holding the Heap_lock.
585 gc_count_before = total_collections();
586 should_try_gc = true;
587 }
588 }
589 }
590
591 if (should_try_gc) {
592 bool succeeded;
593 result = do_collection_pause(word_size, gc_count_before, &succeeded,
594 GCCause::_g1_inc_collection_pause);
595 if (result != NULL) {
596 assert(succeeded, "only way to get back a non-NULL result");
597 return result;
598 }
599
600 if (succeeded) {
601 // If we get here we successfully scheduled a collection which
602 // failed to allocate. No point in trying to allocate
603 // further. We'll just return NULL.
604 MutexLockerEx x(Heap_lock);
605 *gc_count_before_ret = total_collections();
606 return NULL;
607 }
608 } else {
609 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
610 MutexLockerEx x(Heap_lock);
611 *gc_count_before_ret = total_collections();
612 return NULL;
613 }
614 // The GCLocker is either active or the GCLocker initiated
615 // GC has not yet been performed. Stall until it is and
616 // then retry the allocation.
617 GCLocker::stall_until_clear();
618 (*gclocker_retry_count_ret) += 1;
619 }
620
621 // We can reach here if we were unsuccessful in scheduling a
622 // collection (because another thread beat us to it) or if we were
623 // stalled due to the GC locker. In either can we should retry the
624 // allocation attempt in case another thread successfully
625 // performed a collection and reclaimed enough space. We do the
626 // first attempt (without holding the Heap_lock) here and the
627 // follow-on attempt will be at the start of the next loop
628 // iteration (after taking the Heap_lock).
629 result = _allocator->attempt_allocation(word_size, context);
630 if (result != NULL) {
631 return result;
632 }
633
634 // Give a warning if we seem to be looping forever.
635 if ((QueuedAllocationWarningCount > 0) &&
636 (try_count % QueuedAllocationWarningCount == 0)) {
637 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
638 "retries %d times", try_count);
639 }
640 }
641
642 ShouldNotReachHere();
643 return NULL;
644 }
645
646 void G1CollectedHeap::begin_archive_alloc_range() {
647 assert_at_safepoint(true /* should_be_vm_thread */);
648 if (_archive_allocator == NULL) {
649 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
650 }
651 }
652
653 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
654 // Allocations in archive regions cannot be of a size that would be considered
655 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
656 // may be different at archive-restore time.
657 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
658 }
659
660 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
661 assert_at_safepoint(true /* should_be_vm_thread */);
662 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
663 if (is_archive_alloc_too_large(word_size)) {
664 return NULL;
665 }
666 return _archive_allocator->archive_mem_allocate(word_size);
667 }
668
669 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
670 size_t end_alignment_in_bytes) {
671 assert_at_safepoint(true /* should_be_vm_thread */);
672 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
673
674 // Call complete_archive to do the real work, filling in the MemRegion
675 // array with the archive regions.
676 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
677 delete _archive_allocator;
678 _archive_allocator = NULL;
679 }
680
681 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
682 assert(ranges != NULL, "MemRegion array NULL");
683 assert(count != 0, "No MemRegions provided");
684 MemRegion reserved = _hrm.reserved();
685 for (size_t i = 0; i < count; i++) {
686 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
687 return false;
688 }
689 }
690 return true;
691 }
692
693 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
694 assert(!is_init_completed(), "Expect to be called at JVM init time");
695 assert(ranges != NULL, "MemRegion array NULL");
696 assert(count != 0, "No MemRegions provided");
697 MutexLockerEx x(Heap_lock);
698
699 MemRegion reserved = _hrm.reserved();
700 HeapWord* prev_last_addr = NULL;
701 HeapRegion* prev_last_region = NULL;
702
703 // Temporarily disable pretouching of heap pages. This interface is used
704 // when mmap'ing archived heap data in, so pre-touching is wasted.
705 FlagSetting fs(AlwaysPreTouch, false);
706
707 // Enable archive object checking used by G1MarkSweep. We have to let it know
708 // about each archive range, so that objects in those ranges aren't marked.
709 G1ArchiveAllocator::enable_archive_object_check();
710
711 // For each specified MemRegion range, allocate the corresponding G1
712 // regions and mark them as archive regions. We expect the ranges in
713 // ascending starting address order, without overlap.
714 for (size_t i = 0; i < count; i++) {
715 MemRegion curr_range = ranges[i];
716 HeapWord* start_address = curr_range.start();
717 size_t word_size = curr_range.word_size();
718 HeapWord* last_address = curr_range.last();
719 size_t commits = 0;
720
721 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
722 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
723 p2i(start_address), p2i(last_address));
724 guarantee(start_address > prev_last_addr,
725 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
726 p2i(start_address), p2i(prev_last_addr));
727 prev_last_addr = last_address;
728
729 // Check for ranges that start in the same G1 region in which the previous
730 // range ended, and adjust the start address so we don't try to allocate
731 // the same region again. If the current range is entirely within that
732 // region, skip it, just adjusting the recorded top.
733 HeapRegion* start_region = _hrm.addr_to_region(start_address);
734 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
735 start_address = start_region->end();
736 if (start_address > last_address) {
737 increase_used(word_size * HeapWordSize);
738 start_region->set_top(last_address + 1);
739 continue;
740 }
741 start_region->set_top(start_address);
742 curr_range = MemRegion(start_address, last_address + 1);
743 start_region = _hrm.addr_to_region(start_address);
744 }
745
746 // Perform the actual region allocation, exiting if it fails.
747 // Then note how much new space we have allocated.
748 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
749 return false;
750 }
751 increase_used(word_size * HeapWordSize);
752 if (commits != 0) {
753 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
754 HeapRegion::GrainWords * HeapWordSize * commits);
755
756 }
757
758 // Mark each G1 region touched by the range as archive, add it to the old set,
759 // and set the allocation context and top.
760 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
761 HeapRegion* last_region = _hrm.addr_to_region(last_address);
762 prev_last_region = last_region;
763
764 while (curr_region != NULL) {
765 assert(curr_region->is_empty() && !curr_region->is_pinned(),
766 "Region already in use (index %u)", curr_region->hrm_index());
767 curr_region->set_allocation_context(AllocationContext::system());
768 curr_region->set_archive();
769 _hr_printer.alloc(curr_region);
770 _old_set.add(curr_region);
771 if (curr_region != last_region) {
772 curr_region->set_top(curr_region->end());
773 curr_region = _hrm.next_region_in_heap(curr_region);
774 } else {
775 curr_region->set_top(last_address + 1);
776 curr_region = NULL;
777 }
778 }
779
780 // Notify mark-sweep of the archive range.
781 G1ArchiveAllocator::set_range_archive(curr_range, true);
782 }
783 return true;
784 }
785
786 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
787 assert(!is_init_completed(), "Expect to be called at JVM init time");
788 assert(ranges != NULL, "MemRegion array NULL");
789 assert(count != 0, "No MemRegions provided");
790 MemRegion reserved = _hrm.reserved();
791 HeapWord *prev_last_addr = NULL;
792 HeapRegion* prev_last_region = NULL;
793
794 // For each MemRegion, create filler objects, if needed, in the G1 regions
795 // that contain the address range. The address range actually within the
796 // MemRegion will not be modified. That is assumed to have been initialized
797 // elsewhere, probably via an mmap of archived heap data.
798 MutexLockerEx x(Heap_lock);
799 for (size_t i = 0; i < count; i++) {
800 HeapWord* start_address = ranges[i].start();
801 HeapWord* last_address = ranges[i].last();
802
803 assert(reserved.contains(start_address) && reserved.contains(last_address),
804 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
805 p2i(start_address), p2i(last_address));
806 assert(start_address > prev_last_addr,
807 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
808 p2i(start_address), p2i(prev_last_addr));
809
810 HeapRegion* start_region = _hrm.addr_to_region(start_address);
811 HeapRegion* last_region = _hrm.addr_to_region(last_address);
812 HeapWord* bottom_address = start_region->bottom();
813
814 // Check for a range beginning in the same region in which the
815 // previous one ended.
816 if (start_region == prev_last_region) {
817 bottom_address = prev_last_addr + 1;
818 }
819
820 // Verify that the regions were all marked as archive regions by
821 // alloc_archive_regions.
822 HeapRegion* curr_region = start_region;
823 while (curr_region != NULL) {
824 guarantee(curr_region->is_archive(),
825 "Expected archive region at index %u", curr_region->hrm_index());
826 if (curr_region != last_region) {
827 curr_region = _hrm.next_region_in_heap(curr_region);
828 } else {
829 curr_region = NULL;
830 }
831 }
832
833 prev_last_addr = last_address;
834 prev_last_region = last_region;
835
836 // Fill the memory below the allocated range with dummy object(s),
837 // if the region bottom does not match the range start, or if the previous
838 // range ended within the same G1 region, and there is a gap.
839 if (start_address != bottom_address) {
840 size_t fill_size = pointer_delta(start_address, bottom_address);
841 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
842 increase_used(fill_size * HeapWordSize);
843 }
844 }
845 }
846
847 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
848 uint* gc_count_before_ret,
849 uint* gclocker_retry_count_ret) {
850 assert_heap_not_locked_and_not_at_safepoint();
851 assert(!is_humongous(word_size), "attempt_allocation() should not "
852 "be called for humongous allocation requests");
853
854 AllocationContext_t context = AllocationContext::current();
855 HeapWord* result = _allocator->attempt_allocation(word_size, context);
856
857 if (result == NULL) {
858 result = attempt_allocation_slow(word_size,
859 context,
860 gc_count_before_ret,
861 gclocker_retry_count_ret);
862 }
863 assert_heap_not_locked();
864 if (result != NULL) {
865 dirty_young_block(result, word_size);
866 }
867 return result;
868 }
869
870 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
871 assert(!is_init_completed(), "Expect to be called at JVM init time");
872 assert(ranges != NULL, "MemRegion array NULL");
873 assert(count != 0, "No MemRegions provided");
874 MemRegion reserved = _hrm.reserved();
875 HeapWord* prev_last_addr = NULL;
876 HeapRegion* prev_last_region = NULL;
877 size_t size_used = 0;
878 size_t uncommitted_regions = 0;
879
880 // For each Memregion, free the G1 regions that constitute it, and
881 // notify mark-sweep that the range is no longer to be considered 'archive.'
882 MutexLockerEx x(Heap_lock);
883 for (size_t i = 0; i < count; i++) {
884 HeapWord* start_address = ranges[i].start();
885 HeapWord* last_address = ranges[i].last();
886
887 assert(reserved.contains(start_address) && reserved.contains(last_address),
888 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
889 p2i(start_address), p2i(last_address));
890 assert(start_address > prev_last_addr,
891 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
892 p2i(start_address), p2i(prev_last_addr));
893 size_used += ranges[i].byte_size();
894 prev_last_addr = last_address;
895
896 HeapRegion* start_region = _hrm.addr_to_region(start_address);
897 HeapRegion* last_region = _hrm.addr_to_region(last_address);
898
899 // Check for ranges that start in the same G1 region in which the previous
900 // range ended, and adjust the start address so we don't try to free
901 // the same region again. If the current range is entirely within that
902 // region, skip it.
903 if (start_region == prev_last_region) {
904 start_address = start_region->end();
905 if (start_address > last_address) {
906 continue;
907 }
908 start_region = _hrm.addr_to_region(start_address);
909 }
910 prev_last_region = last_region;
911
912 // After verifying that each region was marked as an archive region by
913 // alloc_archive_regions, set it free and empty and uncommit it.
914 HeapRegion* curr_region = start_region;
915 while (curr_region != NULL) {
916 guarantee(curr_region->is_archive(),
917 "Expected archive region at index %u", curr_region->hrm_index());
918 uint curr_index = curr_region->hrm_index();
919 _old_set.remove(curr_region);
920 curr_region->set_free();
921 curr_region->set_top(curr_region->bottom());
922 if (curr_region != last_region) {
923 curr_region = _hrm.next_region_in_heap(curr_region);
924 } else {
925 curr_region = NULL;
926 }
927 _hrm.shrink_at(curr_index, 1);
928 uncommitted_regions++;
929 }
930
931 // Notify mark-sweep that this is no longer an archive range.
932 G1ArchiveAllocator::set_range_archive(ranges[i], false);
933 }
934
935 if (uncommitted_regions != 0) {
936 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
937 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
938 }
939 decrease_used(size_used);
940 }
941
942 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
943 uint* gc_count_before_ret,
944 uint* gclocker_retry_count_ret) {
945 // The structure of this method has a lot of similarities to
946 // attempt_allocation_slow(). The reason these two were not merged
947 // into a single one is that such a method would require several "if
948 // allocation is not humongous do this, otherwise do that"
949 // conditional paths which would obscure its flow. In fact, an early
950 // version of this code did use a unified method which was harder to
951 // follow and, as a result, it had subtle bugs that were hard to
952 // track down. So keeping these two methods separate allows each to
953 // be more readable. It will be good to keep these two in sync as
954 // much as possible.
955
956 assert_heap_not_locked_and_not_at_safepoint();
957 assert(is_humongous(word_size), "attempt_allocation_humongous() "
958 "should only be called for humongous allocations");
959
960 // Humongous objects can exhaust the heap quickly, so we should check if we
961 // need to start a marking cycle at each humongous object allocation. We do
962 // the check before we do the actual allocation. The reason for doing it
963 // before the allocation is that we avoid having to keep track of the newly
964 // allocated memory while we do a GC.
965 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
966 word_size)) {
967 collect(GCCause::_g1_humongous_allocation);
968 }
969
970 // We will loop until a) we manage to successfully perform the
971 // allocation or b) we successfully schedule a collection which
972 // fails to perform the allocation. b) is the only case when we'll
973 // return NULL.
974 HeapWord* result = NULL;
975 for (int try_count = 1; /* we'll return */; try_count += 1) {
976 bool should_try_gc;
977 uint gc_count_before;
978
979 {
980 MutexLockerEx x(Heap_lock);
981
982 // Given that humongous objects are not allocated in young
983 // regions, we'll first try to do the allocation without doing a
984 // collection hoping that there's enough space in the heap.
985 result = humongous_obj_allocate(word_size, AllocationContext::current());
986 if (result != NULL) {
987 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
988 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
989 return result;
990 }
991
992 if (GCLocker::is_active_and_needs_gc()) {
993 should_try_gc = false;
994 } else {
995 // The GCLocker may not be active but the GCLocker initiated
996 // GC may not yet have been performed (GCLocker::needs_gc()
997 // returns true). In this case we do not try this GC and
998 // wait until the GCLocker initiated GC is performed, and
999 // then retry the allocation.
1000 if (GCLocker::needs_gc()) {
1001 should_try_gc = false;
1002 } else {
1003 // Read the GC count while still holding the Heap_lock.
1004 gc_count_before = total_collections();
1005 should_try_gc = true;
1006 }
1007 }
1008 }
1009
1010 if (should_try_gc) {
1011 // If we failed to allocate the humongous object, we should try to
1012 // do a collection pause (if we're allowed) in case it reclaims
1013 // enough space for the allocation to succeed after the pause.
1014
1015 bool succeeded;
1016 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1017 GCCause::_g1_humongous_allocation);
1018 if (result != NULL) {
1019 assert(succeeded, "only way to get back a non-NULL result");
1020 return result;
1021 }
1022
1023 if (succeeded) {
1024 // If we get here we successfully scheduled a collection which
1025 // failed to allocate. No point in trying to allocate
1026 // further. We'll just return NULL.
1027 MutexLockerEx x(Heap_lock);
1028 *gc_count_before_ret = total_collections();
1029 return NULL;
1030 }
1031 } else {
1032 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1033 MutexLockerEx x(Heap_lock);
1034 *gc_count_before_ret = total_collections();
1035 return NULL;
1036 }
1037 // The GCLocker is either active or the GCLocker initiated
1038 // GC has not yet been performed. Stall until it is and
1039 // then retry the allocation.
1040 GCLocker::stall_until_clear();
1041 (*gclocker_retry_count_ret) += 1;
1042 }
1043
1044 // We can reach here if we were unsuccessful in scheduling a
1045 // collection (because another thread beat us to it) or if we were
1046 // stalled due to the GC locker. In either can we should retry the
1047 // allocation attempt in case another thread successfully
1048 // performed a collection and reclaimed enough space. Give a
1049 // warning if we seem to be looping forever.
1050
1051 if ((QueuedAllocationWarningCount > 0) &&
1052 (try_count % QueuedAllocationWarningCount == 0)) {
1053 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1054 "retries %d times", try_count);
1055 }
1056 }
1057
1058 ShouldNotReachHere();
1059 return NULL;
1060 }
1061
1062 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1063 AllocationContext_t context,
1064 bool expect_null_mutator_alloc_region) {
1065 assert_at_safepoint(true /* should_be_vm_thread */);
1066 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1067 "the current alloc region was unexpectedly found to be non-NULL");
1068
1069 if (!is_humongous(word_size)) {
1070 return _allocator->attempt_allocation_locked(word_size, context);
1071 } else {
1072 HeapWord* result = humongous_obj_allocate(word_size, context);
1073 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1074 collector_state()->set_initiate_conc_mark_if_possible(true);
1075 }
1076 return result;
1077 }
1078
1079 ShouldNotReachHere();
1080 }
1081
1082 class PostCompactionPrinterClosure: public HeapRegionClosure {
1083 private:
1084 G1HRPrinter* _hr_printer;
1085 public:
1086 bool doHeapRegion(HeapRegion* hr) {
1087 assert(!hr->is_young(), "not expecting to find young regions");
1088 _hr_printer->post_compaction(hr);
1089 return false;
1090 }
1091
1092 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1093 : _hr_printer(hr_printer) { }
1094 };
1095
1096 void G1CollectedHeap::print_hrm_post_compaction() {
1097 if (_hr_printer.is_active()) {
1098 PostCompactionPrinterClosure cl(hr_printer());
1099 heap_region_iterate(&cl);
1100 }
1101
1102 }
1103
1104 void G1CollectedHeap::abort_concurrent_cycle() {
1105 // Note: When we have a more flexible GC logging framework that
1106 // allows us to add optional attributes to a GC log record we
1107 // could consider timing and reporting how long we wait in the
1108 // following two methods.
1109 wait_while_free_regions_coming();
1110 // If we start the compaction before the CM threads finish
1111 // scanning the root regions we might trip them over as we'll
1112 // be moving objects / updating references. So let's wait until
1113 // they are done. By telling them to abort, they should complete
1114 // early.
1115 _cm->root_regions()->abort();
1116 _cm->root_regions()->wait_until_scan_finished();
1117 append_secondary_free_list_if_not_empty_with_lock();
1118
1119 // Disable discovery and empty the discovered lists
1120 // for the CM ref processor.
1121 ref_processor_cm()->disable_discovery();
1122 ref_processor_cm()->abandon_partial_discovery();
1123 ref_processor_cm()->verify_no_references_recorded();
1124
1125 // Abandon current iterations of concurrent marking and concurrent
1126 // refinement, if any are in progress.
1127 concurrent_mark()->abort();
1128 }
1129
1130 void G1CollectedHeap::prepare_heap_for_full_collection() {
1131 // Make sure we'll choose a new allocation region afterwards.
1132 _allocator->release_mutator_alloc_region();
1133 _allocator->abandon_gc_alloc_regions();
1134 g1_rem_set()->cleanupHRRS();
1135
1136 // We may have added regions to the current incremental collection
1137 // set between the last GC or pause and now. We need to clear the
1138 // incremental collection set and then start rebuilding it afresh
1139 // after this full GC.
1140 abandon_collection_set(collection_set());
1141
1142 tear_down_region_sets(false /* free_list_only */);
1143 collector_state()->set_gcs_are_young(true);
1144 }
1145
1146 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1147 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1148 assert(used() == recalculate_used(), "Should be equal");
1149 _verifier->verify_region_sets_optional();
1150 _verifier->verify_before_gc();
1151 _verifier->check_bitmaps("Full GC Start");
1152 }
1153
1154 void G1CollectedHeap::prepare_heap_for_mutators() {
1155 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1156 ClassLoaderDataGraph::purge();
1157 MetaspaceAux::verify_metrics();
1158
1159 // Prepare heap for normal collections.
1160 assert(num_free_regions() == 0, "we should not have added any free regions");
1161 rebuild_region_sets(false /* free_list_only */);
1162 abort_refinement();
1163 resize_if_necessary_after_full_collection();
1164
1165 // Rebuild the strong code root lists for each region
1166 rebuild_strong_code_roots();
1167
1168 // Start a new incremental collection set for the next pause
1169 start_new_collection_set();
1170
1171 _allocator->init_mutator_alloc_region();
1172
1173 // Post collection state updates.
1174 MetaspaceGC::compute_new_size();
1175 }
1176
1177 void G1CollectedHeap::abort_refinement() {
1178 if (_hot_card_cache->use_cache()) {
1179 _hot_card_cache->reset_card_counts();
1180 _hot_card_cache->reset_hot_cache();
1181 }
1182
1183 // Discard all remembered set updates.
1184 JavaThread::dirty_card_queue_set().abandon_logs();
1185 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1186 }
1187
1188 void G1CollectedHeap::verify_after_full_collection() {
1189 check_gc_time_stamps();
1190 _hrm.verify_optional();
1191 _verifier->verify_region_sets_optional();
1192 _verifier->verify_after_gc();
1193 // Clear the previous marking bitmap, if needed for bitmap verification.
1194 // Note we cannot do this when we clear the next marking bitmap in
1195 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1196 // objects marked during a full GC against the previous bitmap.
1197 // But we need to clear it before calling check_bitmaps below since
1198 // the full GC has compacted objects and updated TAMS but not updated
1199 // the prev bitmap.
1200 if (G1VerifyBitmaps) {
1201 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1202 _cm->clear_prev_bitmap(workers());
1203 }
1204 _verifier->check_bitmaps("Full GC End");
1205
1206 // At this point there should be no regions in the
1207 // entire heap tagged as young.
1208 assert(check_young_list_empty(), "young list should be empty at this point");
1209
1210 // Note: since we've just done a full GC, concurrent
1211 // marking is no longer active. Therefore we need not
1212 // re-enable reference discovery for the CM ref processor.
1213 // That will be done at the start of the next marking cycle.
1214 // We also know that the STW processor should no longer
1215 // discover any new references.
1216 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1217 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1218 ref_processor_stw()->verify_no_references_recorded();
1219 ref_processor_cm()->verify_no_references_recorded();
1220 }
1221
1222 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1223 print_hrm_post_compaction();
1224 heap_transition->print();
1225 print_heap_after_gc();
1226 print_heap_regions();
1227 #ifdef TRACESPINNING
1228 ParallelTaskTerminator::print_termination_counts();
1229 #endif
1230 }
1231
1232 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1233 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1234 g1_policy()->record_full_collection_start();
1235
1236 print_heap_before_gc();
1237 print_heap_regions();
1238
1239 abort_concurrent_cycle();
1240 verify_before_full_collection(scope->is_explicit_gc());
1241
1242 gc_prologue(true);
1243 prepare_heap_for_full_collection();
1244
1245 {
1246 G1FullCollector collector(scope, ref_processor_stw(), concurrent_mark()->nextMarkBitMap(), workers()->active_workers());
1247 // Prepare collection by putting reference processor
1248 // in a correct state.
1249 collector.prepare_collection();
1250
1251 // Do the actual collection.
1252 collector.collect();
1253
1254 collector.complete_collection();
1255 }
1256
1257 prepare_heap_for_mutators();
1258
1259 g1_policy()->record_full_collection_end();
1260 gc_epilogue(true);
1261
1262 // Post collection verification.
1263 verify_after_full_collection();
1264
1265 // Post collection logging.
1266 // We should do this after we potentially resize the heap so
1267 // that all the COMMIT / UNCOMMIT events are generated before
1268 // the compaction events.
1269 print_heap_after_full_collection(scope->heap_transition());
1270 }
1271 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1272 bool clear_all_soft_refs) {
1273 assert_at_safepoint(true /* should_be_vm_thread */);
1274
1275 if (GCLocker::check_active_before_gc()) {
1276 // Full GC was not completed.
1277 return false;
1278 }
1279
1280 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1281 collector_policy()->should_clear_all_soft_refs();
1282
1283 G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1284 do_full_collection_inner(&scope);
1285
1286 // Full collection was successfully completed.
1287 return true;
1288 }
1289
1290 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1291 // Currently, there is no facility in the do_full_collection(bool) API to notify
1292 // the caller that the collection did not succeed (e.g., because it was locked
1293 // out by the GC locker). So, right now, we'll ignore the return value.
1294 bool dummy = do_full_collection(true, /* explicit_gc */
1295 clear_all_soft_refs);
1296 }
1297
1298 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1299 // Include bytes that will be pre-allocated to support collections, as "used".
1300 const size_t used_after_gc = used();
1301 const size_t capacity_after_gc = capacity();
1302 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1303
1304 // This is enforced in arguments.cpp.
1305 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1306 "otherwise the code below doesn't make sense");
1307
1308 // We don't have floating point command-line arguments
1309 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1310 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1311 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1312 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1313
1314 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1315 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1316
1317 // We have to be careful here as these two calculations can overflow
1318 // 32-bit size_t's.
1319 double used_after_gc_d = (double) used_after_gc;
1320 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1321 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1322
1323 // Let's make sure that they are both under the max heap size, which
1324 // by default will make them fit into a size_t.
1325 double desired_capacity_upper_bound = (double) max_heap_size;
1326 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1327 desired_capacity_upper_bound);
1328 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1329 desired_capacity_upper_bound);
1330
1331 // We can now safely turn them into size_t's.
1332 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1333 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1334
1335 // This assert only makes sense here, before we adjust them
1336 // with respect to the min and max heap size.
1337 assert(minimum_desired_capacity <= maximum_desired_capacity,
1338 "minimum_desired_capacity = " SIZE_FORMAT ", "
1339 "maximum_desired_capacity = " SIZE_FORMAT,
1340 minimum_desired_capacity, maximum_desired_capacity);
1341
1342 // Should not be greater than the heap max size. No need to adjust
1343 // it with respect to the heap min size as it's a lower bound (i.e.,
1344 // we'll try to make the capacity larger than it, not smaller).
1345 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1346 // Should not be less than the heap min size. No need to adjust it
1347 // with respect to the heap max size as it's an upper bound (i.e.,
1348 // we'll try to make the capacity smaller than it, not greater).
1349 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1350
1351 if (capacity_after_gc < minimum_desired_capacity) {
1352 // Don't expand unless it's significant
1353 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1354
1355 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1356 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1357 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1358
1359 expand(expand_bytes, _workers);
1360
1361 // No expansion, now see if we want to shrink
1362 } else if (capacity_after_gc > maximum_desired_capacity) {
1363 // Capacity too large, compute shrinking size
1364 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1365
1366 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1367 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1368 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1369
1370 shrink(shrink_bytes);
1371 }
1372 }
1373
1374 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1375 AllocationContext_t context,
1376 bool do_gc,
1377 bool clear_all_soft_refs,
1378 bool expect_null_mutator_alloc_region,
1379 bool* gc_succeeded) {
1380 *gc_succeeded = true;
1381 // Let's attempt the allocation first.
1382 HeapWord* result =
1383 attempt_allocation_at_safepoint(word_size,
1384 context,
1385 expect_null_mutator_alloc_region);
1386 if (result != NULL) {
1387 assert(*gc_succeeded, "sanity");
1388 return result;
1389 }
1390
1391 // In a G1 heap, we're supposed to keep allocation from failing by
1392 // incremental pauses. Therefore, at least for now, we'll favor
1393 // expansion over collection. (This might change in the future if we can
1394 // do something smarter than full collection to satisfy a failed alloc.)
1395 result = expand_and_allocate(word_size, context);
1396 if (result != NULL) {
1397 assert(*gc_succeeded, "sanity");
1398 return result;
1399 }
1400
1401 if (do_gc) {
1402 // Expansion didn't work, we'll try to do a Full GC.
1403 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1404 clear_all_soft_refs);
1405 }
1406
1407 return NULL;
1408 }
1409
1410 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1411 AllocationContext_t context,
1412 bool* succeeded) {
1413 assert_at_safepoint(true /* should_be_vm_thread */);
1414
1415 // Attempts to allocate followed by Full GC.
1416 HeapWord* result =
1417 satisfy_failed_allocation_helper(word_size,
1418 context,
1419 true, /* do_gc */
1420 false, /* clear_all_soft_refs */
1421 false, /* expect_null_mutator_alloc_region */
1422 succeeded);
1423
1424 if (result != NULL || !*succeeded) {
1425 return result;
1426 }
1427
1428 // Attempts to allocate followed by Full GC that will collect all soft references.
1429 result = satisfy_failed_allocation_helper(word_size,
1430 context,
1431 true, /* do_gc */
1432 true, /* clear_all_soft_refs */
1433 true, /* expect_null_mutator_alloc_region */
1434 succeeded);
1435
1436 if (result != NULL || !*succeeded) {
1437 return result;
1438 }
1439
1440 // Attempts to allocate, no GC
1441 result = satisfy_failed_allocation_helper(word_size,
1442 context,
1443 false, /* do_gc */
1444 false, /* clear_all_soft_refs */
1445 true, /* expect_null_mutator_alloc_region */
1446 succeeded);
1447
1448 if (result != NULL) {
1449 assert(*succeeded, "sanity");
1450 return result;
1451 }
1452
1453 assert(!collector_policy()->should_clear_all_soft_refs(),
1454 "Flag should have been handled and cleared prior to this point");
1455
1456 // What else? We might try synchronous finalization later. If the total
1457 // space available is large enough for the allocation, then a more
1458 // complete compaction phase than we've tried so far might be
1459 // appropriate.
1460 assert(*succeeded, "sanity");
1461 return NULL;
1462 }
1463
1464 // Attempting to expand the heap sufficiently
1465 // to support an allocation of the given "word_size". If
1466 // successful, perform the allocation and return the address of the
1467 // allocated block, or else "NULL".
1468
1469 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1470 assert_at_safepoint(true /* should_be_vm_thread */);
1471
1472 _verifier->verify_region_sets_optional();
1473
1474 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1475 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1476 word_size * HeapWordSize);
1477
1478
1479 if (expand(expand_bytes, _workers)) {
1480 _hrm.verify_optional();
1481 _verifier->verify_region_sets_optional();
1482 return attempt_allocation_at_safepoint(word_size,
1483 context,
1484 false /* expect_null_mutator_alloc_region */);
1485 }
1486 return NULL;
1487 }
1488
1489 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1490 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1491 aligned_expand_bytes = align_up(aligned_expand_bytes,
1492 HeapRegion::GrainBytes);
1493
1494 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1495 expand_bytes, aligned_expand_bytes);
1496
1497 if (is_maximal_no_gc()) {
1498 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1499 return false;
1500 }
1501
1502 double expand_heap_start_time_sec = os::elapsedTime();
1503 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1504 assert(regions_to_expand > 0, "Must expand by at least one region");
1505
1506 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1507 if (expand_time_ms != NULL) {
1508 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1509 }
1510
1511 if (expanded_by > 0) {
1512 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1513 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1514 g1_policy()->record_new_heap_size(num_regions());
1515 } else {
1516 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1517
1518 // The expansion of the virtual storage space was unsuccessful.
1519 // Let's see if it was because we ran out of swap.
1520 if (G1ExitOnExpansionFailure &&
1521 _hrm.available() >= regions_to_expand) {
1522 // We had head room...
1523 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1524 }
1525 }
1526 return regions_to_expand > 0;
1527 }
1528
1529 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1530 size_t aligned_shrink_bytes =
1531 ReservedSpace::page_align_size_down(shrink_bytes);
1532 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1533 HeapRegion::GrainBytes);
1534 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1535
1536 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1537 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1538
1539
1540 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",
1541 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1542 if (num_regions_removed > 0) {
1543 g1_policy()->record_new_heap_size(num_regions());
1544 } else {
1545 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1546 }
1547 }
1548
1549 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1550 _verifier->verify_region_sets_optional();
1551
1552 // We should only reach here at the end of a Full GC which means we
1553 // should not not be holding to any GC alloc regions. The method
1554 // below will make sure of that and do any remaining clean up.
1555 _allocator->abandon_gc_alloc_regions();
1556
1557 // Instead of tearing down / rebuilding the free lists here, we
1558 // could instead use the remove_all_pending() method on free_list to
1559 // remove only the ones that we need to remove.
1560 tear_down_region_sets(true /* free_list_only */);
1561 shrink_helper(shrink_bytes);
1562 rebuild_region_sets(true /* free_list_only */);
1563
1564 _hrm.verify_optional();
1565 _verifier->verify_region_sets_optional();
1566 }
1567
1568 // Public methods.
1569
1570 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1571 CollectedHeap(),
1572 _collector_policy(collector_policy),
1573 _g1_policy(create_g1_policy()),
1574 _collection_set(this, _g1_policy),
1575 _dirty_card_queue_set(false),
1576 _is_alive_closure_cm(this),
1577 _is_alive_closure_stw(this),
1578 _ref_processor_cm(NULL),
1579 _ref_processor_stw(NULL),
1580 _bot(NULL),
1581 _hot_card_cache(NULL),
1582 _g1_rem_set(NULL),
1583 _cg1r(NULL),
1584 _g1mm(NULL),
1585 _refine_cte_cl(NULL),
1586 _preserved_marks_set(true /* in_c_heap */),
1587 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1588 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1589 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1590 _humongous_reclaim_candidates(),
1591 _has_humongous_reclaim_candidates(false),
1592 _archive_allocator(NULL),
1593 _free_regions_coming(false),
1594 _gc_time_stamp(0),
1595 _summary_bytes_used(0),
1596 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1597 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1598 _expand_heap_after_alloc_failure(true),
1599 _old_marking_cycles_started(0),
1600 _old_marking_cycles_completed(0),
1601 _in_cset_fast_test(),
1602 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1603 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1604
1605 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1606 /* are_GC_task_threads */true,
1607 /* are_ConcurrentGC_threads */false);
1608 _workers->initialize_workers();
1609 _verifier = new G1HeapVerifier(this);
1610
1611 _allocator = G1Allocator::create_allocator(this);
1612
1613 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1614
1615 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1616
1617 // Override the default _filler_array_max_size so that no humongous filler
1618 // objects are created.
1619 _filler_array_max_size = _humongous_object_threshold_in_words;
1620
1621 uint n_queues = ParallelGCThreads;
1622 _task_queues = new RefToScanQueueSet(n_queues);
1623
1624 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1625
1626 for (uint i = 0; i < n_queues; i++) {
1627 RefToScanQueue* q = new RefToScanQueue();
1628 q->initialize();
1629 _task_queues->register_queue(i, q);
1630 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1631 }
1632
1633 // Initialize the G1EvacuationFailureALot counters and flags.
1634 NOT_PRODUCT(reset_evacuation_should_fail();)
1635
1636 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1637 }
1638
1639 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1640 size_t size,
1641 size_t translation_factor) {
1642 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1643 // Allocate a new reserved space, preferring to use large pages.
1644 ReservedSpace rs(size, preferred_page_size);
1645 G1RegionToSpaceMapper* result =
1646 G1RegionToSpaceMapper::create_mapper(rs,
1647 size,
1648 rs.alignment(),
1649 HeapRegion::GrainBytes,
1650 translation_factor,
1651 mtGC);
1652
1653 os::trace_page_sizes_for_requested_size(description,
1654 size,
1655 preferred_page_size,
1656 rs.alignment(),
1657 rs.base(),
1658 rs.size());
1659
1660 return result;
1661 }
1662
1663 jint G1CollectedHeap::initialize_concurrent_refinement() {
1664 _refine_cte_cl = new RefineCardTableEntryClosure();
1665
1666 jint ecode = JNI_OK;
1667 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1668 return ecode;
1669 }
1670
1671 jint G1CollectedHeap::initialize() {
1672 CollectedHeap::pre_initialize();
1673 os::enable_vtime();
1674
1675 // Necessary to satisfy locking discipline assertions.
1676
1677 MutexLocker x(Heap_lock);
1678
1679 // While there are no constraints in the GC code that HeapWordSize
1680 // be any particular value, there are multiple other areas in the
1681 // system which believe this to be true (e.g. oop->object_size in some
1682 // cases incorrectly returns the size in wordSize units rather than
1683 // HeapWordSize).
1684 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1685
1686 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1687 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1688 size_t heap_alignment = collector_policy()->heap_alignment();
1689
1690 // Ensure that the sizes are properly aligned.
1691 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1692 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1693 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1694
1695 // Reserve the maximum.
1696
1697 // When compressed oops are enabled, the preferred heap base
1698 // is calculated by subtracting the requested size from the
1699 // 32Gb boundary and using the result as the base address for
1700 // heap reservation. If the requested size is not aligned to
1701 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1702 // into the ReservedHeapSpace constructor) then the actual
1703 // base of the reserved heap may end up differing from the
1704 // address that was requested (i.e. the preferred heap base).
1705 // If this happens then we could end up using a non-optimal
1706 // compressed oops mode.
1707
1708 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1709 heap_alignment);
1710
1711 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1712
1713 // Create the barrier set for the entire reserved region.
1714 G1SATBCardTableLoggingModRefBS* bs
1715 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1716 bs->initialize();
1717 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1718 set_barrier_set(bs);
1719
1720 // Create the hot card cache.
1721 _hot_card_cache = new G1HotCardCache(this);
1722
1723 // Carve out the G1 part of the heap.
1724 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1725 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1726 G1RegionToSpaceMapper* heap_storage =
1727 G1RegionToSpaceMapper::create_mapper(g1_rs,
1728 g1_rs.size(),
1729 page_size,
1730 HeapRegion::GrainBytes,
1731 1,
1732 mtJavaHeap);
1733 os::trace_page_sizes("Heap",
1734 collector_policy()->min_heap_byte_size(),
1735 max_byte_size,
1736 page_size,
1737 heap_rs.base(),
1738 heap_rs.size());
1739 heap_storage->set_mapping_changed_listener(&_listener);
1740
1741 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1742 G1RegionToSpaceMapper* bot_storage =
1743 create_aux_memory_mapper("Block Offset Table",
1744 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1745 G1BlockOffsetTable::heap_map_factor());
1746
1747 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1748 G1RegionToSpaceMapper* cardtable_storage =
1749 create_aux_memory_mapper("Card Table",
1750 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1751 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1752
1753 G1RegionToSpaceMapper* card_counts_storage =
1754 create_aux_memory_mapper("Card Counts Table",
1755 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1756 G1CardCounts::heap_map_factor());
1757
1758 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1759 G1RegionToSpaceMapper* prev_bitmap_storage =
1760 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1761 G1RegionToSpaceMapper* next_bitmap_storage =
1762 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1763
1764 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1765 g1_barrier_set()->initialize(cardtable_storage);
1766 // Do later initialization work for concurrent refinement.
1767 _hot_card_cache->initialize(card_counts_storage);
1768
1769 // 6843694 - ensure that the maximum region index can fit
1770 // in the remembered set structures.
1771 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1772 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1773
1774 // Also create a G1 rem set.
1775 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1776 _g1_rem_set->initialize(max_capacity(), max_regions());
1777
1778 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1779 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1780 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1781 "too many cards per region");
1782
1783 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1784
1785 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1786
1787 {
1788 HeapWord* start = _hrm.reserved().start();
1789 HeapWord* end = _hrm.reserved().end();
1790 size_t granularity = HeapRegion::GrainBytes;
1791
1792 _in_cset_fast_test.initialize(start, end, granularity);
1793 _humongous_reclaim_candidates.initialize(start, end, granularity);
1794 }
1795
1796 // Create the G1ConcurrentMark data structure and thread.
1797 // (Must do this late, so that "max_regions" is defined.)
1798 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1799 if (_cm == NULL || !_cm->completed_initialization()) {
1800 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1801 return JNI_ENOMEM;
1802 }
1803 _cmThread = _cm->cmThread();
1804
1805 // Now expand into the initial heap size.
1806 if (!expand(init_byte_size, _workers)) {
1807 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1808 return JNI_ENOMEM;
1809 }
1810
1811 // Perform any initialization actions delegated to the policy.
1812 g1_policy()->init(this, &_collection_set);
1813
1814 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1815 SATB_Q_FL_lock,
1816 G1SATBProcessCompletedThreshold,
1817 Shared_SATB_Q_lock);
1818
1819 jint ecode = initialize_concurrent_refinement();
1820 if (ecode != JNI_OK) {
1821 return ecode;
1822 }
1823
1824 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1825 DirtyCardQ_CBL_mon,
1826 DirtyCardQ_FL_lock,
1827 (int)concurrent_g1_refine()->yellow_zone(),
1828 (int)concurrent_g1_refine()->red_zone(),
1829 Shared_DirtyCardQ_lock,
1830 NULL, // fl_owner
1831 true); // init_free_ids
1832
1833 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1834 DirtyCardQ_CBL_mon,
1835 DirtyCardQ_FL_lock,
1836 -1, // never trigger processing
1837 -1, // no limit on length
1838 Shared_DirtyCardQ_lock,
1839 &JavaThread::dirty_card_queue_set());
1840
1841 // Here we allocate the dummy HeapRegion that is required by the
1842 // G1AllocRegion class.
1843 HeapRegion* dummy_region = _hrm.get_dummy_region();
1844
1845 // We'll re-use the same region whether the alloc region will
1846 // require BOT updates or not and, if it doesn't, then a non-young
1847 // region will complain that it cannot support allocations without
1848 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1849 dummy_region->set_eden();
1850 // Make sure it's full.
1851 dummy_region->set_top(dummy_region->end());
1852 G1AllocRegion::setup(this, dummy_region);
1853
1854 _allocator->init_mutator_alloc_region();
1855
1856 // Do create of the monitoring and management support so that
1857 // values in the heap have been properly initialized.
1858 _g1mm = new G1MonitoringSupport(this);
1859
1860 G1StringDedup::initialize();
1861
1862 _preserved_marks_set.init(ParallelGCThreads);
1863
1864 _collection_set.initialize(max_regions());
1865
1866 return JNI_OK;
1867 }
1868
1869 void G1CollectedHeap::stop() {
1870 // Stop all concurrent threads. We do this to make sure these threads
1871 // do not continue to execute and access resources (e.g. logging)
1872 // that are destroyed during shutdown.
1873 _cg1r->stop();
1874 _cmThread->stop();
1875 if (G1StringDedup::is_enabled()) {
1876 G1StringDedup::stop();
1877 }
1878 }
1879
1880 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1881 return HeapRegion::max_region_size();
1882 }
1883
1884 void G1CollectedHeap::post_initialize() {
1885 ref_processing_init();
1886 }
1887
1888 void G1CollectedHeap::ref_processing_init() {
1889 // Reference processing in G1 currently works as follows:
1890 //
1891 // * There are two reference processor instances. One is
1892 // used to record and process discovered references
1893 // during concurrent marking; the other is used to
1894 // record and process references during STW pauses
1895 // (both full and incremental).
1896 // * Both ref processors need to 'span' the entire heap as
1897 // the regions in the collection set may be dotted around.
1898 //
1899 // * For the concurrent marking ref processor:
1900 // * Reference discovery is enabled at initial marking.
1901 // * Reference discovery is disabled and the discovered
1902 // references processed etc during remarking.
1903 // * Reference discovery is MT (see below).
1904 // * Reference discovery requires a barrier (see below).
1905 // * Reference processing may or may not be MT
1906 // (depending on the value of ParallelRefProcEnabled
1907 // and ParallelGCThreads).
1908 // * A full GC disables reference discovery by the CM
1909 // ref processor and abandons any entries on it's
1910 // discovered lists.
1911 //
1912 // * For the STW processor:
1913 // * Non MT discovery is enabled at the start of a full GC.
1914 // * Processing and enqueueing during a full GC is non-MT.
1915 // * During a full GC, references are processed after marking.
1916 //
1917 // * Discovery (may or may not be MT) is enabled at the start
1918 // of an incremental evacuation pause.
1919 // * References are processed near the end of a STW evacuation pause.
1920 // * For both types of GC:
1921 // * Discovery is atomic - i.e. not concurrent.
1922 // * Reference discovery will not need a barrier.
1923
1924 MemRegion mr = reserved_region();
1925
1926 // Concurrent Mark ref processor
1927 _ref_processor_cm =
1928 new ReferenceProcessor(mr, // span
1929 ParallelRefProcEnabled && (ParallelGCThreads > 1),
1930 // mt processing
1931 ParallelGCThreads,
1932 // degree of mt processing
1933 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1934 // mt discovery
1935 MAX2(ParallelGCThreads, ConcGCThreads),
1936 // degree of mt discovery
1937 false,
1938 // Reference discovery is not atomic
1939 &_is_alive_closure_cm);
1940 // is alive closure
1941 // (for efficiency/performance)
1942
1943 // STW ref processor
1944 _ref_processor_stw =
1945 new ReferenceProcessor(mr, // span
1946 ParallelRefProcEnabled && (ParallelGCThreads > 1),
1947 // mt processing
1948 ParallelGCThreads,
1949 // degree of mt processing
1950 (ParallelGCThreads > 1),
1951 // mt discovery
1952 ParallelGCThreads,
1953 // degree of mt discovery
1954 true,
1955 // Reference discovery is atomic
1956 &_is_alive_closure_stw);
1957 // is alive closure
1958 // (for efficiency/performance)
1959 }
1960
1961 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1962 return _collector_policy;
1963 }
1964
1965 size_t G1CollectedHeap::capacity() const {
1966 return _hrm.length() * HeapRegion::GrainBytes;
1967 }
1968
1969 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1970 hr->reset_gc_time_stamp();
1971 }
1972
1973 #ifndef PRODUCT
1974
1975 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1976 private:
1977 unsigned _gc_time_stamp;
1978 bool _failures;
1979
1980 public:
1981 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1982 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1983
1984 virtual bool doHeapRegion(HeapRegion* hr) {
1985 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1986 if (_gc_time_stamp != region_gc_time_stamp) {
1987 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1988 region_gc_time_stamp, _gc_time_stamp);
1989 _failures = true;
1990 }
1991 return false;
1992 }
1993
1994 bool failures() { return _failures; }
1995 };
1996
1997 void G1CollectedHeap::check_gc_time_stamps() {
1998 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1999 heap_region_iterate(&cl);
2000 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2001 }
2002 #endif // PRODUCT
2003
2004 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2005 _hot_card_cache->drain(cl, worker_i);
2006 }
2007
2008 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2009 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2010 size_t n_completed_buffers = 0;
2011 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2012 n_completed_buffers++;
2013 }
2014 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2015 dcqs.clear_n_completed_buffers();
2016 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2017 }
2018
2019 // Computes the sum of the storage used by the various regions.
2020 size_t G1CollectedHeap::used() const {
2021 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2022 if (_archive_allocator != NULL) {
2023 result += _archive_allocator->used();
2024 }
2025 return result;
2026 }
2027
2028 size_t G1CollectedHeap::used_unlocked() const {
2029 return _summary_bytes_used;
2030 }
2031
2032 class SumUsedClosure: public HeapRegionClosure {
2033 size_t _used;
2034 public:
2035 SumUsedClosure() : _used(0) {}
2036 bool doHeapRegion(HeapRegion* r) {
2037 _used += r->used();
2038 return false;
2039 }
2040 size_t result() { return _used; }
2041 };
2042
2043 size_t G1CollectedHeap::recalculate_used() const {
2044 double recalculate_used_start = os::elapsedTime();
2045
2046 SumUsedClosure blk;
2047 heap_region_iterate(&blk);
2048
2049 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2050 return blk.result();
2051 }
2052
2053 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2054 switch (cause) {
2055 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2056 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2057 case GCCause::_update_allocation_context_stats_inc: return true;
2058 case GCCause::_wb_conc_mark: return true;
2059 default : return false;
2060 }
2061 }
2062
2063 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2064 switch (cause) {
2065 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2066 case GCCause::_g1_humongous_allocation: return true;
2067 default: return is_user_requested_concurrent_full_gc(cause);
2068 }
2069 }
2070
2071 #ifndef PRODUCT
2072 void G1CollectedHeap::allocate_dummy_regions() {
2073 // Let's fill up most of the region
2074 size_t word_size = HeapRegion::GrainWords - 1024;
2075 // And as a result the region we'll allocate will be humongous.
2076 guarantee(is_humongous(word_size), "sanity");
2077
2078 // _filler_array_max_size is set to humongous object threshold
2079 // but temporarily change it to use CollectedHeap::fill_with_object().
2080 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2081
2082 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2083 // Let's use the existing mechanism for the allocation
2084 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2085 AllocationContext::system());
2086 if (dummy_obj != NULL) {
2087 MemRegion mr(dummy_obj, word_size);
2088 CollectedHeap::fill_with_object(mr);
2089 } else {
2090 // If we can't allocate once, we probably cannot allocate
2091 // again. Let's get out of the loop.
2092 break;
2093 }
2094 }
2095 }
2096 #endif // !PRODUCT
2097
2098 void G1CollectedHeap::increment_old_marking_cycles_started() {
2099 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2100 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2101 "Wrong marking cycle count (started: %d, completed: %d)",
2102 _old_marking_cycles_started, _old_marking_cycles_completed);
2103
2104 _old_marking_cycles_started++;
2105 }
2106
2107 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2108 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2109
2110 // We assume that if concurrent == true, then the caller is a
2111 // concurrent thread that was joined the Suspendible Thread
2112 // Set. If there's ever a cheap way to check this, we should add an
2113 // assert here.
2114
2115 // Given that this method is called at the end of a Full GC or of a
2116 // concurrent cycle, and those can be nested (i.e., a Full GC can
2117 // interrupt a concurrent cycle), the number of full collections
2118 // completed should be either one (in the case where there was no
2119 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2120 // behind the number of full collections started.
2121
2122 // This is the case for the inner caller, i.e. a Full GC.
2123 assert(concurrent ||
2124 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2125 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2126 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2127 "is inconsistent with _old_marking_cycles_completed = %u",
2128 _old_marking_cycles_started, _old_marking_cycles_completed);
2129
2130 // This is the case for the outer caller, i.e. the concurrent cycle.
2131 assert(!concurrent ||
2132 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2133 "for outer caller (concurrent cycle): "
2134 "_old_marking_cycles_started = %u "
2135 "is inconsistent with _old_marking_cycles_completed = %u",
2136 _old_marking_cycles_started, _old_marking_cycles_completed);
2137
2138 _old_marking_cycles_completed += 1;
2139
2140 // We need to clear the "in_progress" flag in the CM thread before
2141 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2142 // is set) so that if a waiter requests another System.gc() it doesn't
2143 // incorrectly see that a marking cycle is still in progress.
2144 if (concurrent) {
2145 _cmThread->set_idle();
2146 }
2147
2148 // This notify_all() will ensure that a thread that called
2149 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2150 // and it's waiting for a full GC to finish will be woken up. It is
2151 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2152 FullGCCount_lock->notify_all();
2153 }
2154
2155 void G1CollectedHeap::collect(GCCause::Cause cause) {
2156 assert_heap_not_locked();
2157
2158 uint gc_count_before;
2159 uint old_marking_count_before;
2160 uint full_gc_count_before;
2161 bool retry_gc;
2162
2163 do {
2164 retry_gc = false;
2165
2166 {
2167 MutexLocker ml(Heap_lock);
2168
2169 // Read the GC count while holding the Heap_lock
2170 gc_count_before = total_collections();
2171 full_gc_count_before = total_full_collections();
2172 old_marking_count_before = _old_marking_cycles_started;
2173 }
2174
2175 if (should_do_concurrent_full_gc(cause)) {
2176 // Schedule an initial-mark evacuation pause that will start a
2177 // concurrent cycle. We're setting word_size to 0 which means that
2178 // we are not requesting a post-GC allocation.
2179 VM_G1IncCollectionPause op(gc_count_before,
2180 0, /* word_size */
2181 true, /* should_initiate_conc_mark */
2182 g1_policy()->max_pause_time_ms(),
2183 cause);
2184 op.set_allocation_context(AllocationContext::current());
2185
2186 VMThread::execute(&op);
2187 if (!op.pause_succeeded()) {
2188 if (old_marking_count_before == _old_marking_cycles_started) {
2189 retry_gc = op.should_retry_gc();
2190 } else {
2191 // A Full GC happened while we were trying to schedule the
2192 // initial-mark GC. No point in starting a new cycle given
2193 // that the whole heap was collected anyway.
2194 }
2195
2196 if (retry_gc) {
2197 if (GCLocker::is_active_and_needs_gc()) {
2198 GCLocker::stall_until_clear();
2199 }
2200 }
2201 }
2202 } else {
2203 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2204 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2205
2206 // Schedule a standard evacuation pause. We're setting word_size
2207 // to 0 which means that we are not requesting a post-GC allocation.
2208 VM_G1IncCollectionPause op(gc_count_before,
2209 0, /* word_size */
2210 false, /* should_initiate_conc_mark */
2211 g1_policy()->max_pause_time_ms(),
2212 cause);
2213 VMThread::execute(&op);
2214 } else {
2215 // Schedule a Full GC.
2216 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2217 VMThread::execute(&op);
2218 }
2219 }
2220 } while (retry_gc);
2221 }
2222
2223 bool G1CollectedHeap::is_in(const void* p) const {
2224 if (_hrm.reserved().contains(p)) {
2225 // Given that we know that p is in the reserved space,
2226 // heap_region_containing() should successfully
2227 // return the containing region.
2228 HeapRegion* hr = heap_region_containing(p);
2229 return hr->is_in(p);
2230 } else {
2231 return false;
2232 }
2233 }
2234
2235 #ifdef ASSERT
2236 bool G1CollectedHeap::is_in_exact(const void* p) const {
2237 bool contains = reserved_region().contains(p);
2238 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2239 if (contains && available) {
2240 return true;
2241 } else {
2242 return false;
2243 }
2244 }
2245 #endif
2246
2247 // Iteration functions.
2248
2249 // Iterates an ObjectClosure over all objects within a HeapRegion.
2250
2251 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2252 ObjectClosure* _cl;
2253 public:
2254 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2255 bool doHeapRegion(HeapRegion* r) {
2256 if (!r->is_continues_humongous()) {
2257 r->object_iterate(_cl);
2258 }
2259 return false;
2260 }
2261 };
2262
2263 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2264 IterateObjectClosureRegionClosure blk(cl);
2265 heap_region_iterate(&blk);
2266 }
2267
2268 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2269 _hrm.iterate(cl);
2270 }
2271
2272 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2273 uint worker_id,
2274 HeapRegionClaimerBase *hrclaimer) const {
2275 _hrm.par_iterate(cl, worker_id, hrclaimer);
2276 }
2277
2278 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2279 _collection_set.iterate(cl);
2280 }
2281
2282 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2283 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2284 }
2285
2286 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2287 HeapRegion* hr = heap_region_containing(addr);
2288 return hr->block_start(addr);
2289 }
2290
2291 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2292 HeapRegion* hr = heap_region_containing(addr);
2293 return hr->block_size(addr);
2294 }
2295
2296 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2297 HeapRegion* hr = heap_region_containing(addr);
2298 return hr->block_is_obj(addr);
2299 }
2300
2301 bool G1CollectedHeap::supports_tlab_allocation() const {
2302 return true;
2303 }
2304
2305 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2306 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2307 }
2308
2309 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2310 return _eden.length() * HeapRegion::GrainBytes;
2311 }
2312
2313 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2314 // must be equal to the humongous object limit.
2315 size_t G1CollectedHeap::max_tlab_size() const {
2316 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2317 }
2318
2319 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2320 AllocationContext_t context = AllocationContext::current();
2321 return _allocator->unsafe_max_tlab_alloc(context);
2322 }
2323
2324 size_t G1CollectedHeap::max_capacity() const {
2325 return _hrm.reserved().byte_size();
2326 }
2327
2328 jlong G1CollectedHeap::millis_since_last_gc() {
2329 // See the notes in GenCollectedHeap::millis_since_last_gc()
2330 // for more information about the implementation.
2331 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2332 _g1_policy->collection_pause_end_millis();
2333 if (ret_val < 0) {
2334 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2335 ". returning zero instead.", ret_val);
2336 return 0;
2337 }
2338 return ret_val;
2339 }
2340
2341 void G1CollectedHeap::prepare_for_verify() {
2342 _verifier->prepare_for_verify();
2343 }
2344
2345 void G1CollectedHeap::verify(VerifyOption vo) {
2346 _verifier->verify(vo);
2347 }
2348
2349 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2350 return true;
2351 }
2352
2353 const char* const* G1CollectedHeap::concurrent_phases() const {
2354 return _cmThread->concurrent_phases();
2355 }
2356
2357 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2358 return _cmThread->request_concurrent_phase(phase);
2359 }
2360
2361 class PrintRegionClosure: public HeapRegionClosure {
2362 outputStream* _st;
2363 public:
2364 PrintRegionClosure(outputStream* st) : _st(st) {}
2365 bool doHeapRegion(HeapRegion* r) {
2366 r->print_on(_st);
2367 return false;
2368 }
2369 };
2370
2371 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2372 const HeapRegion* hr,
2373 const VerifyOption vo) const {
2374 switch (vo) {
2375 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2376 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2377 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2378 default: ShouldNotReachHere();
2379 }
2380 return false; // keep some compilers happy
2381 }
2382
2383 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2384 const VerifyOption vo) const {
2385 switch (vo) {
2386 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2387 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2388 case VerifyOption_G1UseMarkWord: {
2389 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2390 return !obj->is_gc_marked() && !hr->is_archive();
2391 }
2392 default: ShouldNotReachHere();
2393 }
2394 return false; // keep some compilers happy
2395 }
2396
2397 void G1CollectedHeap::print_heap_regions() const {
2398 Log(gc, heap, region) log;
2399 if (log.is_trace()) {
2400 ResourceMark rm;
2401 print_regions_on(log.trace_stream());
2402 }
2403 }
2404
2405 void G1CollectedHeap::print_on(outputStream* st) const {
2406 st->print(" %-20s", "garbage-first heap");
2407 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2408 capacity()/K, used_unlocked()/K);
2409 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2410 p2i(_hrm.reserved().start()),
2411 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2412 p2i(_hrm.reserved().end()));
2413 st->cr();
2414 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2415 uint young_regions = young_regions_count();
2416 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2417 (size_t) young_regions * HeapRegion::GrainBytes / K);
2418 uint survivor_regions = survivor_regions_count();
2419 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2420 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2421 st->cr();
2422 MetaspaceAux::print_on(st);
2423 }
2424
2425 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2426 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2427 "HS=humongous(starts), HC=humongous(continues), "
2428 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2429 "AC=allocation context, "
2430 "TAMS=top-at-mark-start (previous, next)");
2431 PrintRegionClosure blk(st);
2432 heap_region_iterate(&blk);
2433 }
2434
2435 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2436 print_on(st);
2437
2438 // Print the per-region information.
2439 print_regions_on(st);
2440 }
2441
2442 void G1CollectedHeap::print_on_error(outputStream* st) const {
2443 this->CollectedHeap::print_on_error(st);
2444
2445 if (_cm != NULL) {
2446 st->cr();
2447 _cm->print_on_error(st);
2448 }
2449 }
2450
2451 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2452 workers()->print_worker_threads_on(st);
2453 _cmThread->print_on(st);
2454 st->cr();
2455 _cm->print_worker_threads_on(st);
2456 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2457 if (G1StringDedup::is_enabled()) {
2458 G1StringDedup::print_worker_threads_on(st);
2459 }
2460 }
2461
2462 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2463 workers()->threads_do(tc);
2464 tc->do_thread(_cmThread);
2465 _cm->threads_do(tc);
2466 _cg1r->threads_do(tc); // also iterates over the sample thread
2467 if (G1StringDedup::is_enabled()) {
2468 G1StringDedup::threads_do(tc);
2469 }
2470 }
2471
2472 void G1CollectedHeap::print_tracing_info() const {
2473 g1_rem_set()->print_summary_info();
2474 concurrent_mark()->print_summary_info();
2475 }
2476
2477 #ifndef PRODUCT
2478 // Helpful for debugging RSet issues.
2479
2480 class PrintRSetsClosure : public HeapRegionClosure {
2481 private:
2482 const char* _msg;
2483 size_t _occupied_sum;
2484
2485 public:
2486 bool doHeapRegion(HeapRegion* r) {
2487 HeapRegionRemSet* hrrs = r->rem_set();
2488 size_t occupied = hrrs->occupied();
2489 _occupied_sum += occupied;
2490
2491 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2492 if (occupied == 0) {
2493 tty->print_cr(" RSet is empty");
2494 } else {
2495 hrrs->print();
2496 }
2497 tty->print_cr("----------");
2498 return false;
2499 }
2500
2501 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2502 tty->cr();
2503 tty->print_cr("========================================");
2504 tty->print_cr("%s", msg);
2505 tty->cr();
2506 }
2507
2508 ~PrintRSetsClosure() {
2509 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2510 tty->print_cr("========================================");
2511 tty->cr();
2512 }
2513 };
2514
2515 void G1CollectedHeap::print_cset_rsets() {
2516 PrintRSetsClosure cl("Printing CSet RSets");
2517 collection_set_iterate(&cl);
2518 }
2519
2520 void G1CollectedHeap::print_all_rsets() {
2521 PrintRSetsClosure cl("Printing All RSets");;
2522 heap_region_iterate(&cl);
2523 }
2524 #endif // PRODUCT
2525
2526 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2527
2528 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2529 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2530 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2531
2532 size_t eden_capacity_bytes =
2533 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2534
2535 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2536 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2537 eden_capacity_bytes, survivor_used_bytes, num_regions());
2538 }
2539
2540 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2541 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2542 stats->unused(), stats->used(), stats->region_end_waste(),
2543 stats->regions_filled(), stats->direct_allocated(),
2544 stats->failure_used(), stats->failure_waste());
2545 }
2546
2547 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2548 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2549 gc_tracer->report_gc_heap_summary(when, heap_summary);
2550
2551 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2552 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2553 }
2554
2555 G1CollectedHeap* G1CollectedHeap::heap() {
2556 CollectedHeap* heap = Universe::heap();
2557 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2558 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2559 return (G1CollectedHeap*)heap;
2560 }
2561
2562 void G1CollectedHeap::gc_prologue(bool full) {
2563 // always_do_update_barrier = false;
2564 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2565
2566 // This summary needs to be printed before incrementing total collections.
2567 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2568
2569 // Update common counters.
2570 increment_total_collections(full /* full gc */);
2571 if (full) {
2572 increment_old_marking_cycles_started();
2573 reset_gc_time_stamp();
2574 } else {
2575 increment_gc_time_stamp();
2576 }
2577
2578 // Fill TLAB's and such
2579 double start = os::elapsedTime();
2580 accumulate_statistics_all_tlabs();
2581 ensure_parsability(true);
2582 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2583 }
2584
2585 void G1CollectedHeap::gc_epilogue(bool full) {
2586 // Update common counters.
2587 if (full) {
2588 // Update the number of full collections that have been completed.
2589 increment_old_marking_cycles_completed(false /* concurrent */);
2590 }
2591
2592 // We are at the end of the GC. Total collections has already been increased.
2593 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2594
2595 // FIXME: what is this about?
2596 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2597 // is set.
2598 #if defined(COMPILER2) || INCLUDE_JVMCI
2599 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2600 #endif
2601 // always_do_update_barrier = true;
2602
2603 double start = os::elapsedTime();
2604 resize_all_tlabs();
2605 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2606
2607 allocation_context_stats().update(full);
2608
2609 MemoryService::track_memory_usage();
2610 // We have just completed a GC. Update the soft reference
2611 // policy with the new heap occupancy
2612 Universe::update_heap_info_at_gc();
2613 }
2614
2615 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2616 uint gc_count_before,
2617 bool* succeeded,
2618 GCCause::Cause gc_cause) {
2619 assert_heap_not_locked_and_not_at_safepoint();
2620 VM_G1IncCollectionPause op(gc_count_before,
2621 word_size,
2622 false, /* should_initiate_conc_mark */
2623 g1_policy()->max_pause_time_ms(),
2624 gc_cause);
2625
2626 op.set_allocation_context(AllocationContext::current());
2627 VMThread::execute(&op);
2628
2629 HeapWord* result = op.result();
2630 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2631 assert(result == NULL || ret_succeeded,
2632 "the result should be NULL if the VM did not succeed");
2633 *succeeded = ret_succeeded;
2634
2635 assert_heap_not_locked();
2636 return result;
2637 }
2638
2639 void
2640 G1CollectedHeap::doConcurrentMark() {
2641 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2642 if (!_cmThread->in_progress()) {
2643 _cmThread->set_started();
2644 CGC_lock->notify();
2645 }
2646 }
2647
2648 size_t G1CollectedHeap::pending_card_num() {
2649 size_t extra_cards = 0;
2650 JavaThread *curr = Threads::first();
2651 while (curr != NULL) {
2652 DirtyCardQueue& dcq = curr->dirty_card_queue();
2653 extra_cards += dcq.size();
2654 curr = curr->next();
2655 }
2656 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2657 size_t buffer_size = dcqs.buffer_size();
2658 size_t buffer_num = dcqs.completed_buffers_num();
2659
2660 return buffer_size * buffer_num + extra_cards;
2661 }
2662
2663 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2664 private:
2665 size_t _total_humongous;
2666 size_t _candidate_humongous;
2667
2668 DirtyCardQueue _dcq;
2669
2670 // We don't nominate objects with many remembered set entries, on
2671 // the assumption that such objects are likely still live.
2672 bool is_remset_small(HeapRegion* region) const {
2673 HeapRegionRemSet* const rset = region->rem_set();
2674 return G1EagerReclaimHumongousObjectsWithStaleRefs
2675 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2676 : rset->is_empty();
2677 }
2678
2679 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2680 assert(region->is_starts_humongous(), "Must start a humongous object");
2681
2682 oop obj = oop(region->bottom());
2683
2684 // Dead objects cannot be eager reclaim candidates. Due to class
2685 // unloading it is unsafe to query their classes so we return early.
2686 if (heap->is_obj_dead(obj, region)) {
2687 return false;
2688 }
2689
2690 // Candidate selection must satisfy the following constraints
2691 // while concurrent marking is in progress:
2692 //
2693 // * In order to maintain SATB invariants, an object must not be
2694 // reclaimed if it was allocated before the start of marking and
2695 // has not had its references scanned. Such an object must have
2696 // its references (including type metadata) scanned to ensure no
2697 // live objects are missed by the marking process. Objects
2698 // allocated after the start of concurrent marking don't need to
2699 // be scanned.
2700 //
2701 // * An object must not be reclaimed if it is on the concurrent
2702 // mark stack. Objects allocated after the start of concurrent
2703 // marking are never pushed on the mark stack.
2704 //
2705 // Nominating only objects allocated after the start of concurrent
2706 // marking is sufficient to meet both constraints. This may miss
2707 // some objects that satisfy the constraints, but the marking data
2708 // structures don't support efficiently performing the needed
2709 // additional tests or scrubbing of the mark stack.
2710 //
2711 // However, we presently only nominate is_typeArray() objects.
2712 // A humongous object containing references induces remembered
2713 // set entries on other regions. In order to reclaim such an
2714 // object, those remembered sets would need to be cleaned up.
2715 //
2716 // We also treat is_typeArray() objects specially, allowing them
2717 // to be reclaimed even if allocated before the start of
2718 // concurrent mark. For this we rely on mark stack insertion to
2719 // exclude is_typeArray() objects, preventing reclaiming an object
2720 // that is in the mark stack. We also rely on the metadata for
2721 // such objects to be built-in and so ensured to be kept live.
2722 // Frequent allocation and drop of large binary blobs is an
2723 // important use case for eager reclaim, and this special handling
2724 // may reduce needed headroom.
2725
2726 return obj->is_typeArray() && is_remset_small(region);
2727 }
2728
2729 public:
2730 RegisterHumongousWithInCSetFastTestClosure()
2731 : _total_humongous(0),
2732 _candidate_humongous(0),
2733 _dcq(&JavaThread::dirty_card_queue_set()) {
2734 }
2735
2736 virtual bool doHeapRegion(HeapRegion* r) {
2737 if (!r->is_starts_humongous()) {
2738 return false;
2739 }
2740 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2741
2742 bool is_candidate = humongous_region_is_candidate(g1h, r);
2743 uint rindex = r->hrm_index();
2744 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2745 if (is_candidate) {
2746 _candidate_humongous++;
2747 g1h->register_humongous_region_with_cset(rindex);
2748 // Is_candidate already filters out humongous object with large remembered sets.
2749 // If we have a humongous object with a few remembered sets, we simply flush these
2750 // remembered set entries into the DCQS. That will result in automatic
2751 // re-evaluation of their remembered set entries during the following evacuation
2752 // phase.
2753 if (!r->rem_set()->is_empty()) {
2754 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2755 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2756 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2757 HeapRegionRemSetIterator hrrs(r->rem_set());
2758 size_t card_index;
2759 while (hrrs.has_next(card_index)) {
2760 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2761 // The remembered set might contain references to already freed
2762 // regions. Filter out such entries to avoid failing card table
2763 // verification.
2764 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2765 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2766 *card_ptr = CardTableModRefBS::dirty_card_val();
2767 _dcq.enqueue(card_ptr);
2768 }
2769 }
2770 }
2771 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2772 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2773 hrrs.n_yielded(), r->rem_set()->occupied());
2774 r->rem_set()->clear_locked();
2775 }
2776 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2777 }
2778 _total_humongous++;
2779
2780 return false;
2781 }
2782
2783 size_t total_humongous() const { return _total_humongous; }
2784 size_t candidate_humongous() const { return _candidate_humongous; }
2785
2786 void flush_rem_set_entries() { _dcq.flush(); }
2787 };
2788
2789 void G1CollectedHeap::register_humongous_regions_with_cset() {
2790 if (!G1EagerReclaimHumongousObjects) {
2791 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2792 return;
2793 }
2794 double time = os::elapsed_counter();
2795
2796 // Collect reclaim candidate information and register candidates with cset.
2797 RegisterHumongousWithInCSetFastTestClosure cl;
2798 heap_region_iterate(&cl);
2799
2800 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2801 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2802 cl.total_humongous(),
2803 cl.candidate_humongous());
2804 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2805
2806 // Finally flush all remembered set entries to re-check into the global DCQS.
2807 cl.flush_rem_set_entries();
2808 }
2809
2810 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2811 public:
2812 bool doHeapRegion(HeapRegion* hr) {
2813 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2814 hr->verify_rem_set();
2815 }
2816 return false;
2817 }
2818 };
2819
2820 uint G1CollectedHeap::num_task_queues() const {
2821 return _task_queues->size();
2822 }
2823
2824 #if TASKQUEUE_STATS
2825 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2826 st->print_raw_cr("GC Task Stats");
2827 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2828 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2829 }
2830
2831 void G1CollectedHeap::print_taskqueue_stats() const {
2832 if (!log_is_enabled(Trace, gc, task, stats)) {
2833 return;
2834 }
2835 Log(gc, task, stats) log;
2836 ResourceMark rm;
2837 outputStream* st = log.trace_stream();
2838
2839 print_taskqueue_stats_hdr(st);
2840
2841 TaskQueueStats totals;
2842 const uint n = num_task_queues();
2843 for (uint i = 0; i < n; ++i) {
2844 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2845 totals += task_queue(i)->stats;
2846 }
2847 st->print_raw("tot "); totals.print(st); st->cr();
2848
2849 DEBUG_ONLY(totals.verify());
2850 }
2851
2852 void G1CollectedHeap::reset_taskqueue_stats() {
2853 const uint n = num_task_queues();
2854 for (uint i = 0; i < n; ++i) {
2855 task_queue(i)->stats.reset();
2856 }
2857 }
2858 #endif // TASKQUEUE_STATS
2859
2860 void G1CollectedHeap::wait_for_root_region_scanning() {
2861 double scan_wait_start = os::elapsedTime();
2862 // We have to wait until the CM threads finish scanning the
2863 // root regions as it's the only way to ensure that all the
2864 // objects on them have been correctly scanned before we start
2865 // moving them during the GC.
2866 bool waited = _cm->root_regions()->wait_until_scan_finished();
2867 double wait_time_ms = 0.0;
2868 if (waited) {
2869 double scan_wait_end = os::elapsedTime();
2870 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2871 }
2872 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2873 }
2874
2875 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2876 private:
2877 G1HRPrinter* _hr_printer;
2878 public:
2879 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2880
2881 virtual bool doHeapRegion(HeapRegion* r) {
2882 _hr_printer->cset(r);
2883 return false;
2884 }
2885 };
2886
2887 void G1CollectedHeap::start_new_collection_set() {
2888 collection_set()->start_incremental_building();
2889
2890 clear_cset_fast_test();
2891
2892 guarantee(_eden.length() == 0, "eden should have been cleared");
2893 g1_policy()->transfer_survivors_to_cset(survivor());
2894 }
2895
2896 bool
2897 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2898 assert_at_safepoint(true /* should_be_vm_thread */);
2899 guarantee(!is_gc_active(), "collection is not reentrant");
2900
2901 if (GCLocker::check_active_before_gc()) {
2902 return false;
2903 }
2904
2905 _gc_timer_stw->register_gc_start();
2906
2907 GCIdMark gc_id_mark;
2908 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2909
2910 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2911 ResourceMark rm;
2912
2913 g1_policy()->note_gc_start();
2914
2915 wait_for_root_region_scanning();
2916
2917 print_heap_before_gc();
2918 print_heap_regions();
2919 trace_heap_before_gc(_gc_tracer_stw);
2920
2921 _verifier->verify_region_sets_optional();
2922 _verifier->verify_dirty_young_regions();
2923
2924 // We should not be doing initial mark unless the conc mark thread is running
2925 if (!_cmThread->should_terminate()) {
2926 // This call will decide whether this pause is an initial-mark
2927 // pause. If it is, during_initial_mark_pause() will return true
2928 // for the duration of this pause.
2929 g1_policy()->decide_on_conc_mark_initiation();
2930 }
2931
2932 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2933 assert(!collector_state()->during_initial_mark_pause() ||
2934 collector_state()->gcs_are_young(), "sanity");
2935
2936 // We also do not allow mixed GCs during marking.
2937 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2938
2939 // Record whether this pause is an initial mark. When the current
2940 // thread has completed its logging output and it's safe to signal
2941 // the CM thread, the flag's value in the policy has been reset.
2942 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2943
2944 // Inner scope for scope based logging, timers, and stats collection
2945 {
2946 EvacuationInfo evacuation_info;
2947
2948 if (collector_state()->during_initial_mark_pause()) {
2949 // We are about to start a marking cycle, so we increment the
2950 // full collection counter.
2951 increment_old_marking_cycles_started();
2952 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2953 }
2954
2955 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2956
2957 GCTraceCPUTime tcpu;
2958
2959 FormatBuffer<> gc_string("Pause ");
2960 if (collector_state()->during_initial_mark_pause()) {
2961 gc_string.append("Initial Mark");
2962 } else if (collector_state()->gcs_are_young()) {
2963 gc_string.append("Young");
2964 } else {
2965 gc_string.append("Mixed");
2966 }
2967 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2968
2969 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2970 workers()->active_workers(),
2971 Threads::number_of_non_daemon_threads());
2972 workers()->update_active_workers(active_workers);
2973 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2974
2975 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2976 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2977
2978 // If the secondary_free_list is not empty, append it to the
2979 // free_list. No need to wait for the cleanup operation to finish;
2980 // the region allocation code will check the secondary_free_list
2981 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2982 // set, skip this step so that the region allocation code has to
2983 // get entries from the secondary_free_list.
2984 if (!G1StressConcRegionFreeing) {
2985 append_secondary_free_list_if_not_empty_with_lock();
2986 }
2987
2988 G1HeapTransition heap_transition(this);
2989 size_t heap_used_bytes_before_gc = used();
2990
2991 // Don't dynamically change the number of GC threads this early. A value of
2992 // 0 is used to indicate serial work. When parallel work is done,
2993 // it will be set.
2994
2995 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2996 IsGCActiveMark x;
2997
2998 gc_prologue(false);
2999
3000 if (VerifyRememberedSets) {
3001 log_info(gc, verify)("[Verifying RemSets before GC]");
3002 VerifyRegionRemSetClosure v_cl;
3003 heap_region_iterate(&v_cl);
3004 }
3005
3006 _verifier->verify_before_gc();
3007
3008 _verifier->check_bitmaps("GC Start");
3009
3010 #if defined(COMPILER2) || INCLUDE_JVMCI
3011 DerivedPointerTable::clear();
3012 #endif
3013
3014 // Please see comment in g1CollectedHeap.hpp and
3015 // G1CollectedHeap::ref_processing_init() to see how
3016 // reference processing currently works in G1.
3017
3018 // Enable discovery in the STW reference processor
3019 if (g1_policy()->should_process_references()) {
3020 ref_processor_stw()->enable_discovery();
3021 } else {
3022 ref_processor_stw()->disable_discovery();
3023 }
3024
3025 {
3026 // We want to temporarily turn off discovery by the
3027 // CM ref processor, if necessary, and turn it back on
3028 // on again later if we do. Using a scoped
3029 // NoRefDiscovery object will do this.
3030 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3031
3032 // Forget the current alloc region (we might even choose it to be part
3033 // of the collection set!).
3034 _allocator->release_mutator_alloc_region();
3035
3036 // This timing is only used by the ergonomics to handle our pause target.
3037 // It is unclear why this should not include the full pause. We will
3038 // investigate this in CR 7178365.
3039 //
3040 // Preserving the old comment here if that helps the investigation:
3041 //
3042 // The elapsed time induced by the start time below deliberately elides
3043 // the possible verification above.
3044 double sample_start_time_sec = os::elapsedTime();
3045
3046 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3047
3048 if (collector_state()->during_initial_mark_pause()) {
3049 concurrent_mark()->checkpointRootsInitialPre();
3050 }
3051
3052 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3053
3054 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3055
3056 // Make sure the remembered sets are up to date. This needs to be
3057 // done before register_humongous_regions_with_cset(), because the
3058 // remembered sets are used there to choose eager reclaim candidates.
3059 // If the remembered sets are not up to date we might miss some
3060 // entries that need to be handled.
3061 g1_rem_set()->cleanupHRRS();
3062
3063 register_humongous_regions_with_cset();
3064
3065 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3066
3067 // We call this after finalize_cset() to
3068 // ensure that the CSet has been finalized.
3069 _cm->verify_no_cset_oops();
3070
3071 if (_hr_printer.is_active()) {
3072 G1PrintCollectionSetClosure cl(&_hr_printer);
3073 _collection_set.iterate(&cl);
3074 }
3075
3076 // Initialize the GC alloc regions.
3077 _allocator->init_gc_alloc_regions(evacuation_info);
3078
3079 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3080 pre_evacuate_collection_set();
3081
3082 // Actually do the work...
3083 evacuate_collection_set(evacuation_info, &per_thread_states);
3084
3085 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3086
3087 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3088 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3089
3090 eagerly_reclaim_humongous_regions();
3091
3092 record_obj_copy_mem_stats();
3093 _survivor_evac_stats.adjust_desired_plab_sz();
3094 _old_evac_stats.adjust_desired_plab_sz();
3095
3096 double start = os::elapsedTime();
3097 start_new_collection_set();
3098 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3099
3100 if (evacuation_failed()) {
3101 set_used(recalculate_used());
3102 if (_archive_allocator != NULL) {
3103 _archive_allocator->clear_used();
3104 }
3105 for (uint i = 0; i < ParallelGCThreads; i++) {
3106 if (_evacuation_failed_info_array[i].has_failed()) {
3107 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3108 }
3109 }
3110 } else {
3111 // The "used" of the the collection set have already been subtracted
3112 // when they were freed. Add in the bytes evacuated.
3113 increase_used(g1_policy()->bytes_copied_during_gc());
3114 }
3115
3116 if (collector_state()->during_initial_mark_pause()) {
3117 // We have to do this before we notify the CM threads that
3118 // they can start working to make sure that all the
3119 // appropriate initialization is done on the CM object.
3120 concurrent_mark()->checkpointRootsInitialPost();
3121 collector_state()->set_mark_in_progress(true);
3122 // Note that we don't actually trigger the CM thread at
3123 // this point. We do that later when we're sure that
3124 // the current thread has completed its logging output.
3125 }
3126
3127 allocate_dummy_regions();
3128
3129 _allocator->init_mutator_alloc_region();
3130
3131 {
3132 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3133 if (expand_bytes > 0) {
3134 size_t bytes_before = capacity();
3135 // No need for an ergo logging here,
3136 // expansion_amount() does this when it returns a value > 0.
3137 double expand_ms;
3138 if (!expand(expand_bytes, _workers, &expand_ms)) {
3139 // We failed to expand the heap. Cannot do anything about it.
3140 }
3141 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3142 }
3143 }
3144
3145 // We redo the verification but now wrt to the new CSet which
3146 // has just got initialized after the previous CSet was freed.
3147 _cm->verify_no_cset_oops();
3148
3149 // This timing is only used by the ergonomics to handle our pause target.
3150 // It is unclear why this should not include the full pause. We will
3151 // investigate this in CR 7178365.
3152 double sample_end_time_sec = os::elapsedTime();
3153 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3154 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3155 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3156
3157 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3158 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3159
3160 if (VerifyRememberedSets) {
3161 log_info(gc, verify)("[Verifying RemSets after GC]");
3162 VerifyRegionRemSetClosure v_cl;
3163 heap_region_iterate(&v_cl);
3164 }
3165
3166 _verifier->verify_after_gc();
3167 _verifier->check_bitmaps("GC End");
3168
3169 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3170 ref_processor_stw()->verify_no_references_recorded();
3171
3172 // CM reference discovery will be re-enabled if necessary.
3173 }
3174
3175 #ifdef TRACESPINNING
3176 ParallelTaskTerminator::print_termination_counts();
3177 #endif
3178
3179 gc_epilogue(false);
3180 }
3181
3182 // Print the remainder of the GC log output.
3183 if (evacuation_failed()) {
3184 log_info(gc)("To-space exhausted");
3185 }
3186
3187 g1_policy()->print_phases();
3188 heap_transition.print();
3189
3190 // It is not yet to safe to tell the concurrent mark to
3191 // start as we have some optional output below. We don't want the
3192 // output from the concurrent mark thread interfering with this
3193 // logging output either.
3194
3195 _hrm.verify_optional();
3196 _verifier->verify_region_sets_optional();
3197
3198 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3199 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3200
3201 print_heap_after_gc();
3202 print_heap_regions();
3203 trace_heap_after_gc(_gc_tracer_stw);
3204
3205 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3206 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3207 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3208 // before any GC notifications are raised.
3209 g1mm()->update_sizes();
3210
3211 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3212 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3213 _gc_timer_stw->register_gc_end();
3214 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3215 }
3216 // It should now be safe to tell the concurrent mark thread to start
3217 // without its logging output interfering with the logging output
3218 // that came from the pause.
3219
3220 if (should_start_conc_mark) {
3221 // CAUTION: after the doConcurrentMark() call below,
3222 // the concurrent marking thread(s) could be running
3223 // concurrently with us. Make sure that anything after
3224 // this point does not assume that we are the only GC thread
3225 // running. Note: of course, the actual marking work will
3226 // not start until the safepoint itself is released in
3227 // SuspendibleThreadSet::desynchronize().
3228 doConcurrentMark();
3229 }
3230
3231 return true;
3232 }
3233
3234 void G1CollectedHeap::remove_self_forwarding_pointers() {
3235 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3236 workers()->run_task(&rsfp_task);
3237 }
3238
3239 void G1CollectedHeap::restore_after_evac_failure() {
3240 double remove_self_forwards_start = os::elapsedTime();
3241
3242 remove_self_forwarding_pointers();
3243 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3244 _preserved_marks_set.restore(&task_executor);
3245
3246 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3247 }
3248
3249 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3250 if (!_evacuation_failed) {
3251 _evacuation_failed = true;
3252 }
3253
3254 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3255 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3256 }
3257
3258 bool G1ParEvacuateFollowersClosure::offer_termination() {
3259 G1ParScanThreadState* const pss = par_scan_state();
3260 start_term_time();
3261 const bool res = terminator()->offer_termination();
3262 end_term_time();
3263 return res;
3264 }
3265
3266 void G1ParEvacuateFollowersClosure::do_void() {
3267 G1ParScanThreadState* const pss = par_scan_state();
3268 pss->trim_queue();
3269 do {
3270 pss->steal_and_trim_queue(queues());
3271 } while (!offer_termination());
3272 }
3273
3274 class G1ParTask : public AbstractGangTask {
3275 protected:
3276 G1CollectedHeap* _g1h;
3277 G1ParScanThreadStateSet* _pss;
3278 RefToScanQueueSet* _queues;
3279 G1RootProcessor* _root_processor;
3280 ParallelTaskTerminator _terminator;
3281 uint _n_workers;
3282
3283 public:
3284 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3285 : AbstractGangTask("G1 collection"),
3286 _g1h(g1h),
3287 _pss(per_thread_states),
3288 _queues(task_queues),
3289 _root_processor(root_processor),
3290 _terminator(n_workers, _queues),
3291 _n_workers(n_workers)
3292 {}
3293
3294 void work(uint worker_id) {
3295 if (worker_id >= _n_workers) return; // no work needed this round
3296
3297 double start_sec = os::elapsedTime();
3298 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3299
3300 {
3301 ResourceMark rm;
3302 HandleMark hm;
3303
3304 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3305
3306 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3307 pss->set_ref_processor(rp);
3308
3309 double start_strong_roots_sec = os::elapsedTime();
3310
3311 _root_processor->evacuate_roots(pss->closures(), worker_id);
3312
3313 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3314 // treating the nmethods visited to act as roots for concurrent marking.
3315 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3316 // objects copied by the current evacuation.
3317 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3318 pss->closures()->weak_codeblobs(),
3319 worker_id);
3320
3321 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3322
3323 double term_sec = 0.0;
3324 size_t evac_term_attempts = 0;
3325 {
3326 double start = os::elapsedTime();
3327 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3328 evac.do_void();
3329
3330 evac_term_attempts = evac.term_attempts();
3331 term_sec = evac.term_time();
3332 double elapsed_sec = os::elapsedTime() - start;
3333 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3334 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3335 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3336 }
3337
3338 assert(pss->queue_is_empty(), "should be empty");
3339
3340 if (log_is_enabled(Debug, gc, task, stats)) {
3341 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3342 size_t lab_waste;
3343 size_t lab_undo_waste;
3344 pss->waste(lab_waste, lab_undo_waste);
3345 _g1h->print_termination_stats(worker_id,
3346 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3347 strong_roots_sec * 1000.0, /* strong roots time */
3348 term_sec * 1000.0, /* evac term time */
3349 evac_term_attempts, /* evac term attempts */
3350 lab_waste, /* alloc buffer waste */
3351 lab_undo_waste /* undo waste */
3352 );
3353 }
3354
3355 // Close the inner scope so that the ResourceMark and HandleMark
3356 // destructors are executed here and are included as part of the
3357 // "GC Worker Time".
3358 }
3359 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3360 }
3361 };
3362
3363 void G1CollectedHeap::print_termination_stats_hdr() {
3364 log_debug(gc, task, stats)("GC Termination Stats");
3365 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3366 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3367 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3368 }
3369
3370 void G1CollectedHeap::print_termination_stats(uint worker_id,
3371 double elapsed_ms,
3372 double strong_roots_ms,
3373 double term_ms,
3374 size_t term_attempts,
3375 size_t alloc_buffer_waste,
3376 size_t undo_waste) const {
3377 log_debug(gc, task, stats)
3378 ("%3d %9.2f %9.2f %6.2f "
3379 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3380 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3381 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3382 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3383 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3384 alloc_buffer_waste * HeapWordSize / K,
3385 undo_waste * HeapWordSize / K);
3386 }
3387
3388 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3389 private:
3390 BoolObjectClosure* _is_alive;
3391 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3392
3393 int _initial_string_table_size;
3394 int _initial_symbol_table_size;
3395
3396 bool _process_strings;
3397 int _strings_processed;
3398 int _strings_removed;
3399
3400 bool _process_symbols;
3401 int _symbols_processed;
3402 int _symbols_removed;
3403
3404 bool _process_string_dedup;
3405
3406 public:
3407 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3408 AbstractGangTask("String/Symbol Unlinking"),
3409 _is_alive(is_alive),
3410 _dedup_closure(is_alive, NULL, false),
3411 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3412 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3413 _process_string_dedup(process_string_dedup) {
3414
3415 _initial_string_table_size = StringTable::the_table()->table_size();
3416 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3417 if (process_strings) {
3418 StringTable::clear_parallel_claimed_index();
3419 }
3420 if (process_symbols) {
3421 SymbolTable::clear_parallel_claimed_index();
3422 }
3423 }
3424
3425 ~G1StringAndSymbolCleaningTask() {
3426 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3427 "claim value %d after unlink less than initial string table size %d",
3428 StringTable::parallel_claimed_index(), _initial_string_table_size);
3429 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3430 "claim value %d after unlink less than initial symbol table size %d",
3431 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3432
3433 log_info(gc, stringtable)(
3434 "Cleaned string and symbol table, "
3435 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3436 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3437 strings_processed(), strings_removed(),
3438 symbols_processed(), symbols_removed());
3439 }
3440
3441 void work(uint worker_id) {
3442 int strings_processed = 0;
3443 int strings_removed = 0;
3444 int symbols_processed = 0;
3445 int symbols_removed = 0;
3446 if (_process_strings) {
3447 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3448 Atomic::add(strings_processed, &_strings_processed);
3449 Atomic::add(strings_removed, &_strings_removed);
3450 }
3451 if (_process_symbols) {
3452 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3453 Atomic::add(symbols_processed, &_symbols_processed);
3454 Atomic::add(symbols_removed, &_symbols_removed);
3455 }
3456 if (_process_string_dedup) {
3457 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3458 }
3459 }
3460
3461 size_t strings_processed() const { return (size_t)_strings_processed; }
3462 size_t strings_removed() const { return (size_t)_strings_removed; }
3463
3464 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3465 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3466 };
3467
3468 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3469 private:
3470 static Monitor* _lock;
3471
3472 BoolObjectClosure* const _is_alive;
3473 const bool _unloading_occurred;
3474 const uint _num_workers;
3475
3476 // Variables used to claim nmethods.
3477 CompiledMethod* _first_nmethod;
3478 volatile CompiledMethod* _claimed_nmethod;
3479
3480 // The list of nmethods that need to be processed by the second pass.
3481 volatile CompiledMethod* _postponed_list;
3482 volatile uint _num_entered_barrier;
3483
3484 public:
3485 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3486 _is_alive(is_alive),
3487 _unloading_occurred(unloading_occurred),
3488 _num_workers(num_workers),
3489 _first_nmethod(NULL),
3490 _claimed_nmethod(NULL),
3491 _postponed_list(NULL),
3492 _num_entered_barrier(0)
3493 {
3494 CompiledMethod::increase_unloading_clock();
3495 // Get first alive nmethod
3496 CompiledMethodIterator iter = CompiledMethodIterator();
3497 if(iter.next_alive()) {
3498 _first_nmethod = iter.method();
3499 }
3500 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3501 }
3502
3503 ~G1CodeCacheUnloadingTask() {
3504 CodeCache::verify_clean_inline_caches();
3505
3506 CodeCache::set_needs_cache_clean(false);
3507 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3508
3509 CodeCache::verify_icholder_relocations();
3510 }
3511
3512 private:
3513 void add_to_postponed_list(CompiledMethod* nm) {
3514 CompiledMethod* old;
3515 do {
3516 old = (CompiledMethod*)_postponed_list;
3517 nm->set_unloading_next(old);
3518 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3519 }
3520
3521 void clean_nmethod(CompiledMethod* nm) {
3522 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3523
3524 if (postponed) {
3525 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3526 add_to_postponed_list(nm);
3527 }
3528
3529 // Mark that this thread has been cleaned/unloaded.
3530 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3531 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3532 }
3533
3534 void clean_nmethod_postponed(CompiledMethod* nm) {
3535 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3536 }
3537
3538 static const int MaxClaimNmethods = 16;
3539
3540 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3541 CompiledMethod* first;
3542 CompiledMethodIterator last;
3543
3544 do {
3545 *num_claimed_nmethods = 0;
3546
3547 first = (CompiledMethod*)_claimed_nmethod;
3548 last = CompiledMethodIterator(first);
3549
3550 if (first != NULL) {
3551
3552 for (int i = 0; i < MaxClaimNmethods; i++) {
3553 if (!last.next_alive()) {
3554 break;
3555 }
3556 claimed_nmethods[i] = last.method();
3557 (*num_claimed_nmethods)++;
3558 }
3559 }
3560
3561 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3562 }
3563
3564 CompiledMethod* claim_postponed_nmethod() {
3565 CompiledMethod* claim;
3566 CompiledMethod* next;
3567
3568 do {
3569 claim = (CompiledMethod*)_postponed_list;
3570 if (claim == NULL) {
3571 return NULL;
3572 }
3573
3574 next = claim->unloading_next();
3575
3576 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3577
3578 return claim;
3579 }
3580
3581 public:
3582 // Mark that we're done with the first pass of nmethod cleaning.
3583 void barrier_mark(uint worker_id) {
3584 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3585 _num_entered_barrier++;
3586 if (_num_entered_barrier == _num_workers) {
3587 ml.notify_all();
3588 }
3589 }
3590
3591 // See if we have to wait for the other workers to
3592 // finish their first-pass nmethod cleaning work.
3593 void barrier_wait(uint worker_id) {
3594 if (_num_entered_barrier < _num_workers) {
3595 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3596 while (_num_entered_barrier < _num_workers) {
3597 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3598 }
3599 }
3600 }
3601
3602 // Cleaning and unloading of nmethods. Some work has to be postponed
3603 // to the second pass, when we know which nmethods survive.
3604 void work_first_pass(uint worker_id) {
3605 // The first nmethods is claimed by the first worker.
3606 if (worker_id == 0 && _first_nmethod != NULL) {
3607 clean_nmethod(_first_nmethod);
3608 _first_nmethod = NULL;
3609 }
3610
3611 int num_claimed_nmethods;
3612 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3613
3614 while (true) {
3615 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3616
3617 if (num_claimed_nmethods == 0) {
3618 break;
3619 }
3620
3621 for (int i = 0; i < num_claimed_nmethods; i++) {
3622 clean_nmethod(claimed_nmethods[i]);
3623 }
3624 }
3625 }
3626
3627 void work_second_pass(uint worker_id) {
3628 CompiledMethod* nm;
3629 // Take care of postponed nmethods.
3630 while ((nm = claim_postponed_nmethod()) != NULL) {
3631 clean_nmethod_postponed(nm);
3632 }
3633 }
3634 };
3635
3636 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3637
3638 class G1KlassCleaningTask : public StackObj {
3639 BoolObjectClosure* _is_alive;
3640 volatile jint _clean_klass_tree_claimed;
3641 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3642
3643 public:
3644 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3645 _is_alive(is_alive),
3646 _clean_klass_tree_claimed(0),
3647 _klass_iterator() {
3648 }
3649
3650 private:
3651 bool claim_clean_klass_tree_task() {
3652 if (_clean_klass_tree_claimed) {
3653 return false;
3654 }
3655
3656 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3657 }
3658
3659 InstanceKlass* claim_next_klass() {
3660 Klass* klass;
3661 do {
3662 klass =_klass_iterator.next_klass();
3663 } while (klass != NULL && !klass->is_instance_klass());
3664
3665 // this can be null so don't call InstanceKlass::cast
3666 return static_cast<InstanceKlass*>(klass);
3667 }
3668
3669 public:
3670
3671 void clean_klass(InstanceKlass* ik) {
3672 ik->clean_weak_instanceklass_links(_is_alive);
3673 }
3674
3675 void work() {
3676 ResourceMark rm;
3677
3678 // One worker will clean the subklass/sibling klass tree.
3679 if (claim_clean_klass_tree_task()) {
3680 Klass::clean_subklass_tree(_is_alive);
3681 }
3682
3683 // All workers will help cleaning the classes,
3684 InstanceKlass* klass;
3685 while ((klass = claim_next_klass()) != NULL) {
3686 clean_klass(klass);
3687 }
3688 }
3689 };
3690
3691 class G1ResolvedMethodCleaningTask : public StackObj {
3692 BoolObjectClosure* _is_alive;
3693 volatile jint _resolved_method_task_claimed;
3694 public:
3695 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3696 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3697
3698 bool claim_resolved_method_task() {
3699 if (_resolved_method_task_claimed) {
3700 return false;
3701 }
3702 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3703 }
3704
3705 // These aren't big, one thread can do it all.
3706 void work() {
3707 if (claim_resolved_method_task()) {
3708 ResolvedMethodTable::unlink(_is_alive);
3709 }
3710 }
3711 };
3712
3713
3714 // To minimize the remark pause times, the tasks below are done in parallel.
3715 class G1ParallelCleaningTask : public AbstractGangTask {
3716 private:
3717 G1StringAndSymbolCleaningTask _string_symbol_task;
3718 G1CodeCacheUnloadingTask _code_cache_task;
3719 G1KlassCleaningTask _klass_cleaning_task;
3720 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3721
3722 public:
3723 // The constructor is run in the VMThread.
3724 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3725 AbstractGangTask("Parallel Cleaning"),
3726 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3727 _code_cache_task(num_workers, is_alive, unloading_occurred),
3728 _klass_cleaning_task(is_alive),
3729 _resolved_method_cleaning_task(is_alive) {
3730 }
3731
3732 // The parallel work done by all worker threads.
3733 void work(uint worker_id) {
3734 // Do first pass of code cache cleaning.
3735 _code_cache_task.work_first_pass(worker_id);
3736
3737 // Let the threads mark that the first pass is done.
3738 _code_cache_task.barrier_mark(worker_id);
3739
3740 // Clean the Strings and Symbols.
3741 _string_symbol_task.work(worker_id);
3742
3743 // Clean unreferenced things in the ResolvedMethodTable
3744 _resolved_method_cleaning_task.work();
3745
3746 // Wait for all workers to finish the first code cache cleaning pass.
3747 _code_cache_task.barrier_wait(worker_id);
3748
3749 // Do the second code cache cleaning work, which realize on
3750 // the liveness information gathered during the first pass.
3751 _code_cache_task.work_second_pass(worker_id);
3752
3753 // Clean all klasses that were not unloaded.
3754 _klass_cleaning_task.work();
3755 }
3756 };
3757
3758
3759 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3760 bool class_unloading_occurred) {
3761 uint n_workers = workers()->active_workers();
3762
3763 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3764 workers()->run_task(&g1_unlink_task);
3765 }
3766
3767 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3768 bool process_strings,
3769 bool process_symbols,
3770 bool process_string_dedup) {
3771 if (!process_strings && !process_symbols && !process_string_dedup) {
3772 // Nothing to clean.
3773 return;
3774 }
3775
3776 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3777 workers()->run_task(&g1_unlink_task);
3778
3779 }
3780
3781 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3782 private:
3783 DirtyCardQueueSet* _queue;
3784 G1CollectedHeap* _g1h;
3785 public:
3786 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3787 _queue(queue), _g1h(g1h) { }
3788
3789 virtual void work(uint worker_id) {
3790 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3791 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3792
3793 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3794 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3795
3796 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3797 }
3798 };
3799
3800 void G1CollectedHeap::redirty_logged_cards() {
3801 double redirty_logged_cards_start = os::elapsedTime();
3802
3803 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3804 dirty_card_queue_set().reset_for_par_iteration();
3805 workers()->run_task(&redirty_task);
3806
3807 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3808 dcq.merge_bufferlists(&dirty_card_queue_set());
3809 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3810
3811 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3812 }
3813
3814 // Weak Reference Processing support
3815
3816 // An always "is_alive" closure that is used to preserve referents.
3817 // If the object is non-null then it's alive. Used in the preservation
3818 // of referent objects that are pointed to by reference objects
3819 // discovered by the CM ref processor.
3820 class G1AlwaysAliveClosure: public BoolObjectClosure {
3821 G1CollectedHeap* _g1;
3822 public:
3823 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3824 bool do_object_b(oop p) {
3825 if (p != NULL) {
3826 return true;
3827 }
3828 return false;
3829 }
3830 };
3831
3832 bool G1STWIsAliveClosure::do_object_b(oop p) {
3833 // An object is reachable if it is outside the collection set,
3834 // or is inside and copied.
3835 return !_g1->is_in_cset(p) || p->is_forwarded();
3836 }
3837
3838 // Non Copying Keep Alive closure
3839 class G1KeepAliveClosure: public OopClosure {
3840 G1CollectedHeap* _g1;
3841 public:
3842 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3843 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3844 void do_oop(oop* p) {
3845 oop obj = *p;
3846 assert(obj != NULL, "the caller should have filtered out NULL values");
3847
3848 const InCSetState cset_state = _g1->in_cset_state(obj);
3849 if (!cset_state.is_in_cset_or_humongous()) {
3850 return;
3851 }
3852 if (cset_state.is_in_cset()) {
3853 assert( obj->is_forwarded(), "invariant" );
3854 *p = obj->forwardee();
3855 } else {
3856 assert(!obj->is_forwarded(), "invariant" );
3857 assert(cset_state.is_humongous(),
3858 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3859 _g1->set_humongous_is_live(obj);
3860 }
3861 }
3862 };
3863
3864 // Copying Keep Alive closure - can be called from both
3865 // serial and parallel code as long as different worker
3866 // threads utilize different G1ParScanThreadState instances
3867 // and different queues.
3868
3869 class G1CopyingKeepAliveClosure: public OopClosure {
3870 G1CollectedHeap* _g1h;
3871 OopClosure* _copy_non_heap_obj_cl;
3872 G1ParScanThreadState* _par_scan_state;
3873
3874 public:
3875 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3876 OopClosure* non_heap_obj_cl,
3877 G1ParScanThreadState* pss):
3878 _g1h(g1h),
3879 _copy_non_heap_obj_cl(non_heap_obj_cl),
3880 _par_scan_state(pss)
3881 {}
3882
3883 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3884 virtual void do_oop( oop* p) { do_oop_work(p); }
3885
3886 template <class T> void do_oop_work(T* p) {
3887 oop obj = oopDesc::load_decode_heap_oop(p);
3888
3889 if (_g1h->is_in_cset_or_humongous(obj)) {
3890 // If the referent object has been forwarded (either copied
3891 // to a new location or to itself in the event of an
3892 // evacuation failure) then we need to update the reference
3893 // field and, if both reference and referent are in the G1
3894 // heap, update the RSet for the referent.
3895 //
3896 // If the referent has not been forwarded then we have to keep
3897 // it alive by policy. Therefore we have copy the referent.
3898 //
3899 // If the reference field is in the G1 heap then we can push
3900 // on the PSS queue. When the queue is drained (after each
3901 // phase of reference processing) the object and it's followers
3902 // will be copied, the reference field set to point to the
3903 // new location, and the RSet updated. Otherwise we need to
3904 // use the the non-heap or metadata closures directly to copy
3905 // the referent object and update the pointer, while avoiding
3906 // updating the RSet.
3907
3908 if (_g1h->is_in_g1_reserved(p)) {
3909 _par_scan_state->push_on_queue(p);
3910 } else {
3911 assert(!Metaspace::contains((const void*)p),
3912 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3913 _copy_non_heap_obj_cl->do_oop(p);
3914 }
3915 }
3916 }
3917 };
3918
3919 // Serial drain queue closure. Called as the 'complete_gc'
3920 // closure for each discovered list in some of the
3921 // reference processing phases.
3922
3923 class G1STWDrainQueueClosure: public VoidClosure {
3924 protected:
3925 G1CollectedHeap* _g1h;
3926 G1ParScanThreadState* _par_scan_state;
3927
3928 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3929
3930 public:
3931 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3932 _g1h(g1h),
3933 _par_scan_state(pss)
3934 { }
3935
3936 void do_void() {
3937 G1ParScanThreadState* const pss = par_scan_state();
3938 pss->trim_queue();
3939 }
3940 };
3941
3942 // Parallel Reference Processing closures
3943
3944 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3945 // processing during G1 evacuation pauses.
3946
3947 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3948 private:
3949 G1CollectedHeap* _g1h;
3950 G1ParScanThreadStateSet* _pss;
3951 RefToScanQueueSet* _queues;
3952 WorkGang* _workers;
3953 uint _active_workers;
3954
3955 public:
3956 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3957 G1ParScanThreadStateSet* per_thread_states,
3958 WorkGang* workers,
3959 RefToScanQueueSet *task_queues,
3960 uint n_workers) :
3961 _g1h(g1h),
3962 _pss(per_thread_states),
3963 _queues(task_queues),
3964 _workers(workers),
3965 _active_workers(n_workers)
3966 {
3967 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3968 }
3969
3970 // Executes the given task using concurrent marking worker threads.
3971 virtual void execute(ProcessTask& task);
3972 virtual void execute(EnqueueTask& task);
3973 };
3974
3975 // Gang task for possibly parallel reference processing
3976
3977 class G1STWRefProcTaskProxy: public AbstractGangTask {
3978 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3979 ProcessTask& _proc_task;
3980 G1CollectedHeap* _g1h;
3981 G1ParScanThreadStateSet* _pss;
3982 RefToScanQueueSet* _task_queues;
3983 ParallelTaskTerminator* _terminator;
3984
3985 public:
3986 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3987 G1CollectedHeap* g1h,
3988 G1ParScanThreadStateSet* per_thread_states,
3989 RefToScanQueueSet *task_queues,
3990 ParallelTaskTerminator* terminator) :
3991 AbstractGangTask("Process reference objects in parallel"),
3992 _proc_task(proc_task),
3993 _g1h(g1h),
3994 _pss(per_thread_states),
3995 _task_queues(task_queues),
3996 _terminator(terminator)
3997 {}
3998
3999 virtual void work(uint worker_id) {
4000 // The reference processing task executed by a single worker.
4001 ResourceMark rm;
4002 HandleMark hm;
4003
4004 G1STWIsAliveClosure is_alive(_g1h);
4005
4006 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4007 pss->set_ref_processor(NULL);
4008
4009 // Keep alive closure.
4010 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4011
4012 // Complete GC closure
4013 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4014
4015 // Call the reference processing task's work routine.
4016 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4017
4018 // Note we cannot assert that the refs array is empty here as not all
4019 // of the processing tasks (specifically phase2 - pp2_work) execute
4020 // the complete_gc closure (which ordinarily would drain the queue) so
4021 // the queue may not be empty.
4022 }
4023 };
4024
4025 // Driver routine for parallel reference processing.
4026 // Creates an instance of the ref processing gang
4027 // task and has the worker threads execute it.
4028 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4029 assert(_workers != NULL, "Need parallel worker threads.");
4030
4031 ParallelTaskTerminator terminator(_active_workers, _queues);
4032 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4033
4034 _workers->run_task(&proc_task_proxy);
4035 }
4036
4037 // Gang task for parallel reference enqueueing.
4038
4039 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4040 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4041 EnqueueTask& _enq_task;
4042
4043 public:
4044 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4045 AbstractGangTask("Enqueue reference objects in parallel"),
4046 _enq_task(enq_task)
4047 { }
4048
4049 virtual void work(uint worker_id) {
4050 _enq_task.work(worker_id);
4051 }
4052 };
4053
4054 // Driver routine for parallel reference enqueueing.
4055 // Creates an instance of the ref enqueueing gang
4056 // task and has the worker threads execute it.
4057
4058 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4059 assert(_workers != NULL, "Need parallel worker threads.");
4060
4061 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4062
4063 _workers->run_task(&enq_task_proxy);
4064 }
4065
4066 // End of weak reference support closures
4067
4068 // Abstract task used to preserve (i.e. copy) any referent objects
4069 // that are in the collection set and are pointed to by reference
4070 // objects discovered by the CM ref processor.
4071
4072 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4073 protected:
4074 G1CollectedHeap* _g1h;
4075 G1ParScanThreadStateSet* _pss;
4076 RefToScanQueueSet* _queues;
4077 ParallelTaskTerminator _terminator;
4078 uint _n_workers;
4079
4080 public:
4081 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4082 AbstractGangTask("ParPreserveCMReferents"),
4083 _g1h(g1h),
4084 _pss(per_thread_states),
4085 _queues(task_queues),
4086 _terminator(workers, _queues),
4087 _n_workers(workers)
4088 {
4089 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4090 }
4091
4092 void work(uint worker_id) {
4093 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4094
4095 ResourceMark rm;
4096 HandleMark hm;
4097
4098 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4099 pss->set_ref_processor(NULL);
4100 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4101
4102 // Is alive closure
4103 G1AlwaysAliveClosure always_alive(_g1h);
4104
4105 // Copying keep alive closure. Applied to referent objects that need
4106 // to be copied.
4107 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4108
4109 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4110
4111 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4112 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4113
4114 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4115 // So this must be true - but assert just in case someone decides to
4116 // change the worker ids.
4117 assert(worker_id < limit, "sanity");
4118 assert(!rp->discovery_is_atomic(), "check this code");
4119
4120 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4121 for (uint idx = worker_id; idx < limit; idx += stride) {
4122 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4123
4124 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4125 while (iter.has_next()) {
4126 // Since discovery is not atomic for the CM ref processor, we
4127 // can see some null referent objects.
4128 iter.load_ptrs(DEBUG_ONLY(true));
4129 oop ref = iter.obj();
4130
4131 // This will filter nulls.
4132 if (iter.is_referent_alive()) {
4133 iter.make_referent_alive();
4134 }
4135 iter.move_to_next();
4136 }
4137 }
4138
4139 // Drain the queue - which may cause stealing
4140 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4141 drain_queue.do_void();
4142 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4143 assert(pss->queue_is_empty(), "should be");
4144 }
4145 };
4146
4147 void G1CollectedHeap::process_weak_jni_handles() {
4148 double ref_proc_start = os::elapsedTime();
4149
4150 G1STWIsAliveClosure is_alive(this);
4151 G1KeepAliveClosure keep_alive(this);
4152 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4153
4154 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4155 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4156 }
4157
4158 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4159 // Any reference objects, in the collection set, that were 'discovered'
4160 // by the CM ref processor should have already been copied (either by
4161 // applying the external root copy closure to the discovered lists, or
4162 // by following an RSet entry).
4163 //
4164 // But some of the referents, that are in the collection set, that these
4165 // reference objects point to may not have been copied: the STW ref
4166 // processor would have seen that the reference object had already
4167 // been 'discovered' and would have skipped discovering the reference,
4168 // but would not have treated the reference object as a regular oop.
4169 // As a result the copy closure would not have been applied to the
4170 // referent object.
4171 //
4172 // We need to explicitly copy these referent objects - the references
4173 // will be processed at the end of remarking.
4174 //
4175 // We also need to do this copying before we process the reference
4176 // objects discovered by the STW ref processor in case one of these
4177 // referents points to another object which is also referenced by an
4178 // object discovered by the STW ref processor.
4179 double preserve_cm_referents_time = 0.0;
4180
4181 // To avoid spawning task when there is no work to do, check that
4182 // a concurrent cycle is active and that some references have been
4183 // discovered.
4184 if (concurrent_mark()->cmThread()->during_cycle() &&
4185 ref_processor_cm()->has_discovered_references()) {
4186 double preserve_cm_referents_start = os::elapsedTime();
4187 uint no_of_gc_workers = workers()->active_workers();
4188 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4189 per_thread_states,
4190 no_of_gc_workers,
4191 _task_queues);
4192 workers()->run_task(&keep_cm_referents);
4193 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4194 }
4195
4196 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4197 }
4198
4199 // Weak Reference processing during an evacuation pause (part 1).
4200 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4201 double ref_proc_start = os::elapsedTime();
4202
4203 ReferenceProcessor* rp = _ref_processor_stw;
4204 assert(rp->discovery_enabled(), "should have been enabled");
4205
4206 // Closure to test whether a referent is alive.
4207 G1STWIsAliveClosure is_alive(this);
4208
4209 // Even when parallel reference processing is enabled, the processing
4210 // of JNI refs is serial and performed serially by the current thread
4211 // rather than by a worker. The following PSS will be used for processing
4212 // JNI refs.
4213
4214 // Use only a single queue for this PSS.
4215 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4216 pss->set_ref_processor(NULL);
4217 assert(pss->queue_is_empty(), "pre-condition");
4218
4219 // Keep alive closure.
4220 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4221
4222 // Serial Complete GC closure
4223 G1STWDrainQueueClosure drain_queue(this, pss);
4224
4225 // Setup the soft refs policy...
4226 rp->setup_policy(false);
4227
4228 ReferenceProcessorStats stats;
4229 if (!rp->processing_is_mt()) {
4230 // Serial reference processing...
4231 stats = rp->process_discovered_references(&is_alive,
4232 &keep_alive,
4233 &drain_queue,
4234 NULL,
4235 _gc_timer_stw);
4236 } else {
4237 uint no_of_gc_workers = workers()->active_workers();
4238
4239 // Parallel reference processing
4240 assert(no_of_gc_workers <= rp->max_num_q(),
4241 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4242 no_of_gc_workers, rp->max_num_q());
4243
4244 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4245 stats = rp->process_discovered_references(&is_alive,
4246 &keep_alive,
4247 &drain_queue,
4248 &par_task_executor,
4249 _gc_timer_stw);
4250 }
4251
4252 _gc_tracer_stw->report_gc_reference_stats(stats);
4253
4254 // We have completed copying any necessary live referent objects.
4255 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4256
4257 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4258 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4259 }
4260
4261 // Weak Reference processing during an evacuation pause (part 2).
4262 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4263 double ref_enq_start = os::elapsedTime();
4264
4265 ReferenceProcessor* rp = _ref_processor_stw;
4266 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4267
4268 // Now enqueue any remaining on the discovered lists on to
4269 // the pending list.
4270 if (!rp->processing_is_mt()) {
4271 // Serial reference processing...
4272 rp->enqueue_discovered_references();
4273 } else {
4274 // Parallel reference enqueueing
4275
4276 uint n_workers = workers()->active_workers();
4277
4278 assert(n_workers <= rp->max_num_q(),
4279 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4280 n_workers, rp->max_num_q());
4281
4282 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4283 rp->enqueue_discovered_references(&par_task_executor);
4284 }
4285
4286 rp->verify_no_references_recorded();
4287 assert(!rp->discovery_enabled(), "should have been disabled");
4288
4289 // FIXME
4290 // CM's reference processing also cleans up the string and symbol tables.
4291 // Should we do that here also? We could, but it is a serial operation
4292 // and could significantly increase the pause time.
4293
4294 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4295 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4296 }
4297
4298 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4299 double merge_pss_time_start = os::elapsedTime();
4300 per_thread_states->flush();
4301 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4302 }
4303
4304 void G1CollectedHeap::pre_evacuate_collection_set() {
4305 _expand_heap_after_alloc_failure = true;
4306 _evacuation_failed = false;
4307
4308 // Disable the hot card cache.
4309 _hot_card_cache->reset_hot_cache_claimed_index();
4310 _hot_card_cache->set_use_cache(false);
4311
4312 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4313 _preserved_marks_set.assert_empty();
4314
4315 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4316
4317 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4318 if (collector_state()->during_initial_mark_pause()) {
4319 double start_clear_claimed_marks = os::elapsedTime();
4320
4321 ClassLoaderDataGraph::clear_claimed_marks();
4322
4323 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4324 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4325 }
4326 }
4327
4328 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4329 // Should G1EvacuationFailureALot be in effect for this GC?
4330 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4331
4332 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4333
4334 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4335
4336 double start_par_time_sec = os::elapsedTime();
4337 double end_par_time_sec;
4338
4339 {
4340 const uint n_workers = workers()->active_workers();
4341 G1RootProcessor root_processor(this, n_workers);
4342 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4343
4344 print_termination_stats_hdr();
4345
4346 workers()->run_task(&g1_par_task);
4347 end_par_time_sec = os::elapsedTime();
4348
4349 // Closing the inner scope will execute the destructor
4350 // for the G1RootProcessor object. We record the current
4351 // elapsed time before closing the scope so that time
4352 // taken for the destructor is NOT included in the
4353 // reported parallel time.
4354 }
4355
4356 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4357 phase_times->record_par_time(par_time_ms);
4358
4359 double code_root_fixup_time_ms =
4360 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4361 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4362 }
4363
4364 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4365 // Process any discovered reference objects - we have
4366 // to do this _before_ we retire the GC alloc regions
4367 // as we may have to copy some 'reachable' referent
4368 // objects (and their reachable sub-graphs) that were
4369 // not copied during the pause.
4370 if (g1_policy()->should_process_references()) {
4371 preserve_cm_referents(per_thread_states);
4372 process_discovered_references(per_thread_states);
4373 } else {
4374 ref_processor_stw()->verify_no_references_recorded();
4375 process_weak_jni_handles();
4376 }
4377
4378 if (G1StringDedup::is_enabled()) {
4379 double fixup_start = os::elapsedTime();
4380
4381 G1STWIsAliveClosure is_alive(this);
4382 G1KeepAliveClosure keep_alive(this);
4383 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4384
4385 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4386 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4387 }
4388
4389 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4390
4391 if (evacuation_failed()) {
4392 restore_after_evac_failure();
4393
4394 // Reset the G1EvacuationFailureALot counters and flags
4395 // Note: the values are reset only when an actual
4396 // evacuation failure occurs.
4397 NOT_PRODUCT(reset_evacuation_should_fail();)
4398 }
4399
4400 _preserved_marks_set.assert_empty();
4401
4402 // Enqueue any remaining references remaining on the STW
4403 // reference processor's discovered lists. We need to do
4404 // this after the card table is cleaned (and verified) as
4405 // the act of enqueueing entries on to the pending list
4406 // will log these updates (and dirty their associated
4407 // cards). We need these updates logged to update any
4408 // RSets.
4409 if (g1_policy()->should_process_references()) {
4410 enqueue_discovered_references(per_thread_states);
4411 } else {
4412 g1_policy()->phase_times()->record_ref_enq_time(0);
4413 }
4414
4415 _allocator->release_gc_alloc_regions(evacuation_info);
4416
4417 merge_per_thread_state_info(per_thread_states);
4418
4419 // Reset and re-enable the hot card cache.
4420 // Note the counts for the cards in the regions in the
4421 // collection set are reset when the collection set is freed.
4422 _hot_card_cache->reset_hot_cache();
4423 _hot_card_cache->set_use_cache(true);
4424
4425 purge_code_root_memory();
4426
4427 redirty_logged_cards();
4428 #if defined(COMPILER2) || INCLUDE_JVMCI
4429 double start = os::elapsedTime();
4430 DerivedPointerTable::update_pointers();
4431 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4432 #endif
4433 g1_policy()->print_age_table();
4434 }
4435
4436 void G1CollectedHeap::record_obj_copy_mem_stats() {
4437 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4438
4439 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4440 create_g1_evac_summary(&_old_evac_stats));
4441 }
4442
4443 void G1CollectedHeap::free_region(HeapRegion* hr,
4444 FreeRegionList* free_list,
4445 bool skip_remset,
4446 bool skip_hot_card_cache,
4447 bool locked) {
4448 assert(!hr->is_free(), "the region should not be free");
4449 assert(!hr->is_empty(), "the region should not be empty");
4450 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4451 assert(free_list != NULL, "pre-condition");
4452
4453 if (G1VerifyBitmaps) {
4454 MemRegion mr(hr->bottom(), hr->end());
4455 concurrent_mark()->clearRangePrevBitmap(mr);
4456 }
4457
4458 // Clear the card counts for this region.
4459 // Note: we only need to do this if the region is not young
4460 // (since we don't refine cards in young regions).
4461 if (!skip_hot_card_cache && !hr->is_young()) {
4462 _hot_card_cache->reset_card_counts(hr);
4463 }
4464 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4465 free_list->add_ordered(hr);
4466 }
4467
4468 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4469 FreeRegionList* free_list,
4470 bool skip_remset) {
4471 assert(hr->is_humongous(), "this is only for humongous regions");
4472 assert(free_list != NULL, "pre-condition");
4473 hr->clear_humongous();
4474 free_region(hr, free_list, skip_remset);
4475 }
4476
4477 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4478 const uint humongous_regions_removed) {
4479 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4480 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4481 _old_set.bulk_remove(old_regions_removed);
4482 _humongous_set.bulk_remove(humongous_regions_removed);
4483 }
4484
4485 }
4486
4487 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4488 assert(list != NULL, "list can't be null");
4489 if (!list->is_empty()) {
4490 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4491 _hrm.insert_list_into_free_list(list);
4492 }
4493 }
4494
4495 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4496 decrease_used(bytes);
4497 }
4498
4499 class G1ParScrubRemSetTask: public AbstractGangTask {
4500 protected:
4501 G1RemSet* _g1rs;
4502 HeapRegionClaimer _hrclaimer;
4503
4504 public:
4505 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4506 AbstractGangTask("G1 ScrubRS"),
4507 _g1rs(g1_rs),
4508 _hrclaimer(num_workers) {
4509 }
4510
4511 void work(uint worker_id) {
4512 _g1rs->scrub(worker_id, &_hrclaimer);
4513 }
4514 };
4515
4516 void G1CollectedHeap::scrub_rem_set() {
4517 uint num_workers = workers()->active_workers();
4518 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4519 workers()->run_task(&g1_par_scrub_rs_task);
4520 }
4521
4522 class G1FreeCollectionSetTask : public AbstractGangTask {
4523 private:
4524
4525 // Closure applied to all regions in the collection set to do work that needs to
4526 // be done serially in a single thread.
4527 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4528 private:
4529 EvacuationInfo* _evacuation_info;
4530 const size_t* _surviving_young_words;
4531
4532 // Bytes used in successfully evacuated regions before the evacuation.
4533 size_t _before_used_bytes;
4534 // Bytes used in unsucessfully evacuated regions before the evacuation
4535 size_t _after_used_bytes;
4536
4537 size_t _bytes_allocated_in_old_since_last_gc;
4538
4539 size_t _failure_used_words;
4540 size_t _failure_waste_words;
4541
4542 FreeRegionList _local_free_list;
4543 public:
4544 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4545 HeapRegionClosure(),
4546 _evacuation_info(evacuation_info),
4547 _surviving_young_words(surviving_young_words),
4548 _before_used_bytes(0),
4549 _after_used_bytes(0),
4550 _bytes_allocated_in_old_since_last_gc(0),
4551 _failure_used_words(0),
4552 _failure_waste_words(0),
4553 _local_free_list("Local Region List for CSet Freeing") {
4554 }
4555
4556 virtual bool doHeapRegion(HeapRegion* r) {
4557 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4558
4559 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4560 g1h->clear_in_cset(r);
4561
4562 if (r->is_young()) {
4563 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4564 "Young index %d is wrong for region %u of type %s with %u young regions",
4565 r->young_index_in_cset(),
4566 r->hrm_index(),
4567 r->get_type_str(),
4568 g1h->collection_set()->young_region_length());
4569 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4570 r->record_surv_words_in_group(words_survived);
4571 }
4572
4573 if (!r->evacuation_failed()) {
4574 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4575 _before_used_bytes += r->used();
4576 g1h->free_region(r,
4577 &_local_free_list,
4578 true, /* skip_remset */
4579 true, /* skip_hot_card_cache */
4580 true /* locked */);
4581 } else {
4582 r->uninstall_surv_rate_group();
4583 r->set_young_index_in_cset(-1);
4584 r->set_evacuation_failed(false);
4585 // When moving a young gen region to old gen, we "allocate" that whole region
4586 // there. This is in addition to any already evacuated objects. Notify the
4587 // policy about that.
4588 // Old gen regions do not cause an additional allocation: both the objects
4589 // still in the region and the ones already moved are accounted for elsewhere.
4590 if (r->is_young()) {
4591 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4592 }
4593 // The region is now considered to be old.
4594 r->set_old();
4595 // Do some allocation statistics accounting. Regions that failed evacuation
4596 // are always made old, so there is no need to update anything in the young
4597 // gen statistics, but we need to update old gen statistics.
4598 size_t used_words = r->marked_bytes() / HeapWordSize;
4599
4600 _failure_used_words += used_words;
4601 _failure_waste_words += HeapRegion::GrainWords - used_words;
4602
4603 g1h->old_set_add(r);
4604 _after_used_bytes += r->used();
4605 }
4606 return false;
4607 }
4608
4609 void complete_work() {
4610 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4611
4612 _evacuation_info->set_regions_freed(_local_free_list.length());
4613 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4614
4615 g1h->prepend_to_freelist(&_local_free_list);
4616 g1h->decrement_summary_bytes(_before_used_bytes);
4617
4618 G1Policy* policy = g1h->g1_policy();
4619 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4620
4621 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4622 }
4623 };
4624
4625 G1CollectionSet* _collection_set;
4626 G1SerialFreeCollectionSetClosure _cl;
4627 const size_t* _surviving_young_words;
4628
4629 size_t _rs_lengths;
4630
4631 volatile jint _serial_work_claim;
4632
4633 struct WorkItem {
4634 uint region_idx;
4635 bool is_young;
4636 bool evacuation_failed;
4637
4638 WorkItem(HeapRegion* r) {
4639 region_idx = r->hrm_index();
4640 is_young = r->is_young();
4641 evacuation_failed = r->evacuation_failed();
4642 }
4643 };
4644
4645 volatile size_t _parallel_work_claim;
4646 size_t _num_work_items;
4647 WorkItem* _work_items;
4648
4649 void do_serial_work() {
4650 // Need to grab the lock to be allowed to modify the old region list.
4651 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4652 _collection_set->iterate(&_cl);
4653 }
4654
4655 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4656 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4657
4658 HeapRegion* r = g1h->region_at(region_idx);
4659 assert(!g1h->is_on_master_free_list(r), "sanity");
4660
4661 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4662
4663 if (!is_young) {
4664 g1h->_hot_card_cache->reset_card_counts(r);
4665 }
4666
4667 if (!evacuation_failed) {
4668 r->rem_set()->clear_locked();
4669 }
4670 }
4671
4672 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4673 private:
4674 size_t _cur_idx;
4675 WorkItem* _work_items;
4676 public:
4677 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4678
4679 virtual bool doHeapRegion(HeapRegion* r) {
4680 _work_items[_cur_idx++] = WorkItem(r);
4681 return false;
4682 }
4683 };
4684
4685 void prepare_work() {
4686 G1PrepareFreeCollectionSetClosure cl(_work_items);
4687 _collection_set->iterate(&cl);
4688 }
4689
4690 void complete_work() {
4691 _cl.complete_work();
4692
4693 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4694 policy->record_max_rs_lengths(_rs_lengths);
4695 policy->cset_regions_freed();
4696 }
4697 public:
4698 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4699 AbstractGangTask("G1 Free Collection Set"),
4700 _cl(evacuation_info, surviving_young_words),
4701 _collection_set(collection_set),
4702 _surviving_young_words(surviving_young_words),
4703 _serial_work_claim(0),
4704 _rs_lengths(0),
4705 _parallel_work_claim(0),
4706 _num_work_items(collection_set->region_length()),
4707 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4708 prepare_work();
4709 }
4710
4711 ~G1FreeCollectionSetTask() {
4712 complete_work();
4713 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4714 }
4715
4716 // Chunk size for work distribution. The chosen value has been determined experimentally
4717 // to be a good tradeoff between overhead and achievable parallelism.
4718 static uint chunk_size() { return 32; }
4719
4720 virtual void work(uint worker_id) {
4721 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4722
4723 // Claim serial work.
4724 if (_serial_work_claim == 0) {
4725 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4726 if (value == 0) {
4727 double serial_time = os::elapsedTime();
4728 do_serial_work();
4729 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4730 }
4731 }
4732
4733 // Start parallel work.
4734 double young_time = 0.0;
4735 bool has_young_time = false;
4736 double non_young_time = 0.0;
4737 bool has_non_young_time = false;
4738
4739 while (true) {
4740 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4741 size_t cur = end - chunk_size();
4742
4743 if (cur >= _num_work_items) {
4744 break;
4745 }
4746
4747 double start_time = os::elapsedTime();
4748
4749 end = MIN2(end, _num_work_items);
4750
4751 for (; cur < end; cur++) {
4752 bool is_young = _work_items[cur].is_young;
4753
4754 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4755
4756 double end_time = os::elapsedTime();
4757 double time_taken = end_time - start_time;
4758 if (is_young) {
4759 young_time += time_taken;
4760 has_young_time = true;
4761 } else {
4762 non_young_time += time_taken;
4763 has_non_young_time = true;
4764 }
4765 start_time = end_time;
4766 }
4767 }
4768
4769 if (has_young_time) {
4770 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4771 }
4772 if (has_non_young_time) {
4773 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4774 }
4775 }
4776 };
4777
4778 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4779 _eden.clear();
4780
4781 double free_cset_start_time = os::elapsedTime();
4782
4783 {
4784 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4785 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4786
4787 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4788
4789 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4790 cl.name(),
4791 num_workers,
4792 _collection_set.region_length());
4793 workers()->run_task(&cl, num_workers);
4794 }
4795 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4796
4797 collection_set->clear();
4798 }
4799
4800 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4801 private:
4802 FreeRegionList* _free_region_list;
4803 HeapRegionSet* _proxy_set;
4804 uint _humongous_objects_reclaimed;
4805 uint _humongous_regions_reclaimed;
4806 size_t _freed_bytes;
4807 public:
4808
4809 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4810 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4811 }
4812
4813 virtual bool doHeapRegion(HeapRegion* r) {
4814 if (!r->is_starts_humongous()) {
4815 return false;
4816 }
4817
4818 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4819
4820 oop obj = (oop)r->bottom();
4821 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4822
4823 // The following checks whether the humongous object is live are sufficient.
4824 // The main additional check (in addition to having a reference from the roots
4825 // or the young gen) is whether the humongous object has a remembered set entry.
4826 //
4827 // A humongous object cannot be live if there is no remembered set for it
4828 // because:
4829 // - there can be no references from within humongous starts regions referencing
4830 // the object because we never allocate other objects into them.
4831 // (I.e. there are no intra-region references that may be missed by the
4832 // remembered set)
4833 // - as soon there is a remembered set entry to the humongous starts region
4834 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4835 // until the end of a concurrent mark.
4836 //
4837 // It is not required to check whether the object has been found dead by marking
4838 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4839 // all objects allocated during that time are considered live.
4840 // SATB marking is even more conservative than the remembered set.
4841 // So if at this point in the collection there is no remembered set entry,
4842 // nobody has a reference to it.
4843 // At the start of collection we flush all refinement logs, and remembered sets
4844 // are completely up-to-date wrt to references to the humongous object.
4845 //
4846 // Other implementation considerations:
4847 // - never consider object arrays at this time because they would pose
4848 // considerable effort for cleaning up the the remembered sets. This is
4849 // required because stale remembered sets might reference locations that
4850 // are currently allocated into.
4851 uint region_idx = r->hrm_index();
4852 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4853 !r->rem_set()->is_empty()) {
4854 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",
4855 region_idx,
4856 (size_t)obj->size() * HeapWordSize,
4857 p2i(r->bottom()),
4858 r->rem_set()->occupied(),
4859 r->rem_set()->strong_code_roots_list_length(),
4860 next_bitmap->isMarked(r->bottom()),
4861 g1h->is_humongous_reclaim_candidate(region_idx),
4862 obj->is_typeArray()
4863 );
4864 return false;
4865 }
4866
4867 guarantee(obj->is_typeArray(),
4868 "Only eagerly reclaiming type arrays is supported, but the object "
4869 PTR_FORMAT " is not.", p2i(r->bottom()));
4870
4871 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",
4872 region_idx,
4873 (size_t)obj->size() * HeapWordSize,
4874 p2i(r->bottom()),
4875 r->rem_set()->occupied(),
4876 r->rem_set()->strong_code_roots_list_length(),
4877 next_bitmap->isMarked(r->bottom()),
4878 g1h->is_humongous_reclaim_candidate(region_idx),
4879 obj->is_typeArray()
4880 );
4881
4882 // Need to clear mark bit of the humongous object if already set.
4883 if (next_bitmap->isMarked(r->bottom())) {
4884 next_bitmap->clear(r->bottom());
4885 }
4886 _humongous_objects_reclaimed++;
4887 do {
4888 HeapRegion* next = g1h->next_region_in_humongous(r);
4889 _freed_bytes += r->used();
4890 r->set_containing_set(NULL);
4891 _humongous_regions_reclaimed++;
4892 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4893 r = next;
4894 } while (r != NULL);
4895
4896 return false;
4897 }
4898
4899 uint humongous_objects_reclaimed() {
4900 return _humongous_objects_reclaimed;
4901 }
4902
4903 uint humongous_regions_reclaimed() {
4904 return _humongous_regions_reclaimed;
4905 }
4906
4907 size_t bytes_freed() const {
4908 return _freed_bytes;
4909 }
4910 };
4911
4912 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4913 assert_at_safepoint(true);
4914
4915 if (!G1EagerReclaimHumongousObjects ||
4916 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4917 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4918 return;
4919 }
4920
4921 double start_time = os::elapsedTime();
4922
4923 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4924
4925 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4926 heap_region_iterate(&cl);
4927
4928 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4929
4930 G1HRPrinter* hrp = hr_printer();
4931 if (hrp->is_active()) {
4932 FreeRegionListIterator iter(&local_cleanup_list);
4933 while (iter.more_available()) {
4934 HeapRegion* hr = iter.get_next();
4935 hrp->cleanup(hr);
4936 }
4937 }
4938
4939 prepend_to_freelist(&local_cleanup_list);
4940 decrement_summary_bytes(cl.bytes_freed());
4941
4942 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4943 cl.humongous_objects_reclaimed());
4944 }
4945
4946 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4947 public:
4948 virtual bool doHeapRegion(HeapRegion* r) {
4949 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4950 G1CollectedHeap::heap()->clear_in_cset(r);
4951 r->set_young_index_in_cset(-1);
4952 return false;
4953 }
4954 };
4955
4956 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4957 G1AbandonCollectionSetClosure cl;
4958 collection_set->iterate(&cl);
4959
4960 collection_set->clear();
4961 collection_set->stop_incremental_building();
4962 }
4963
4964 void G1CollectedHeap::set_free_regions_coming() {
4965 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4966
4967 assert(!free_regions_coming(), "pre-condition");
4968 _free_regions_coming = true;
4969 }
4970
4971 void G1CollectedHeap::reset_free_regions_coming() {
4972 assert(free_regions_coming(), "pre-condition");
4973
4974 {
4975 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4976 _free_regions_coming = false;
4977 SecondaryFreeList_lock->notify_all();
4978 }
4979
4980 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4981 }
4982
4983 void G1CollectedHeap::wait_while_free_regions_coming() {
4984 // Most of the time we won't have to wait, so let's do a quick test
4985 // first before we take the lock.
4986 if (!free_regions_coming()) {
4987 return;
4988 }
4989
4990 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4991
4992 {
4993 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4994 while (free_regions_coming()) {
4995 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4996 }
4997 }
4998
4999 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5000 }
5001
5002 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5003 return _allocator->is_retained_old_region(hr);
5004 }
5005
5006 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5007 _eden.add(hr);
5008 _g1_policy->set_region_eden(hr);
5009 }
5010
5011 #ifdef ASSERT
5012
5013 class NoYoungRegionsClosure: public HeapRegionClosure {
5014 private:
5015 bool _success;
5016 public:
5017 NoYoungRegionsClosure() : _success(true) { }
5018 bool doHeapRegion(HeapRegion* r) {
5019 if (r->is_young()) {
5020 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5021 p2i(r->bottom()), p2i(r->end()));
5022 _success = false;
5023 }
5024 return false;
5025 }
5026 bool success() { return _success; }
5027 };
5028
5029 bool G1CollectedHeap::check_young_list_empty() {
5030 bool ret = (young_regions_count() == 0);
5031
5032 NoYoungRegionsClosure closure;
5033 heap_region_iterate(&closure);
5034 ret = ret && closure.success();
5035
5036 return ret;
5037 }
5038
5039 #endif // ASSERT
5040
5041 class TearDownRegionSetsClosure : public HeapRegionClosure {
5042 private:
5043 HeapRegionSet *_old_set;
5044
5045 public:
5046 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5047
5048 bool doHeapRegion(HeapRegion* r) {
5049 if (r->is_old()) {
5050 _old_set->remove(r);
5051 } else if(r->is_young()) {
5052 r->uninstall_surv_rate_group();
5053 } else {
5054 // We ignore free regions, we'll empty the free list afterwards.
5055 // We ignore humongous regions, we're not tearing down the
5056 // humongous regions set.
5057 assert(r->is_free() || r->is_humongous(),
5058 "it cannot be another type");
5059 }
5060 return false;
5061 }
5062
5063 ~TearDownRegionSetsClosure() {
5064 assert(_old_set->is_empty(), "post-condition");
5065 }
5066 };
5067
5068 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5069 assert_at_safepoint(true /* should_be_vm_thread */);
5070
5071 if (!free_list_only) {
5072 TearDownRegionSetsClosure cl(&_old_set);
5073 heap_region_iterate(&cl);
5074
5075 // Note that emptying the _young_list is postponed and instead done as
5076 // the first step when rebuilding the regions sets again. The reason for
5077 // this is that during a full GC string deduplication needs to know if
5078 // a collected region was young or old when the full GC was initiated.
5079 }
5080 _hrm.remove_all_free_regions();
5081 }
5082
5083 void G1CollectedHeap::increase_used(size_t bytes) {
5084 _summary_bytes_used += bytes;
5085 }
5086
5087 void G1CollectedHeap::decrease_used(size_t bytes) {
5088 assert(_summary_bytes_used >= bytes,
5089 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5090 _summary_bytes_used, bytes);
5091 _summary_bytes_used -= bytes;
5092 }
5093
5094 void G1CollectedHeap::set_used(size_t bytes) {
5095 _summary_bytes_used = bytes;
5096 }
5097
5098 class RebuildRegionSetsClosure : public HeapRegionClosure {
5099 private:
5100 bool _free_list_only;
5101 HeapRegionSet* _old_set;
5102 HeapRegionManager* _hrm;
5103 size_t _total_used;
5104
5105 public:
5106 RebuildRegionSetsClosure(bool free_list_only,
5107 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5108 _free_list_only(free_list_only),
5109 _old_set(old_set), _hrm(hrm), _total_used(0) {
5110 assert(_hrm->num_free_regions() == 0, "pre-condition");
5111 if (!free_list_only) {
5112 assert(_old_set->is_empty(), "pre-condition");
5113 }
5114 }
5115
5116 bool doHeapRegion(HeapRegion* r) {
5117 if (r->is_empty()) {
5118 // Add free regions to the free list
5119 r->set_free();
5120 r->set_allocation_context(AllocationContext::system());
5121 _hrm->insert_into_free_list(r);
5122 } else if (!_free_list_only) {
5123
5124 if (r->is_humongous()) {
5125 // We ignore humongous regions. We left the humongous set unchanged.
5126 } else {
5127 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5128 // We now consider all regions old, so register as such. Leave
5129 // archive regions set that way, however, while still adding
5130 // them to the old set.
5131 if (!r->is_archive()) {
5132 r->set_old();
5133 }
5134 _old_set->add(r);
5135 }
5136 _total_used += r->used();
5137 }
5138
5139 return false;
5140 }
5141
5142 size_t total_used() {
5143 return _total_used;
5144 }
5145 };
5146
5147 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5148 assert_at_safepoint(true /* should_be_vm_thread */);
5149
5150 if (!free_list_only) {
5151 _eden.clear();
5152 _survivor.clear();
5153 }
5154
5155 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5156 heap_region_iterate(&cl);
5157
5158 if (!free_list_only) {
5159 set_used(cl.total_used());
5160 if (_archive_allocator != NULL) {
5161 _archive_allocator->clear_used();
5162 }
5163 }
5164 assert(used_unlocked() == recalculate_used(),
5165 "inconsistent used_unlocked(), "
5166 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5167 used_unlocked(), recalculate_used());
5168 }
5169
5170 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5171 _refine_cte_cl->set_concurrent(concurrent);
5172 }
5173
5174 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5175 HeapRegion* hr = heap_region_containing(p);
5176 return hr->is_in(p);
5177 }
5178
5179 // Methods for the mutator alloc region
5180
5181 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5182 bool force) {
5183 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5184 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5185 if (force || should_allocate) {
5186 HeapRegion* new_alloc_region = new_region(word_size,
5187 false /* is_old */,
5188 false /* do_expand */);
5189 if (new_alloc_region != NULL) {
5190 set_region_short_lived_locked(new_alloc_region);
5191 _hr_printer.alloc(new_alloc_region, !should_allocate);
5192 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5193 return new_alloc_region;
5194 }
5195 }
5196 return NULL;
5197 }
5198
5199 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5200 size_t allocated_bytes) {
5201 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5202 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5203
5204 collection_set()->add_eden_region(alloc_region);
5205 increase_used(allocated_bytes);
5206 _hr_printer.retire(alloc_region);
5207 // We update the eden sizes here, when the region is retired,
5208 // instead of when it's allocated, since this is the point that its
5209 // used space has been recored in _summary_bytes_used.
5210 g1mm()->update_eden_size();
5211 }
5212
5213 // Methods for the GC alloc regions
5214
5215 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5216 if (dest.is_old()) {
5217 return true;
5218 } else {
5219 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5220 }
5221 }
5222
5223 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5224 assert(FreeList_lock->owned_by_self(), "pre-condition");
5225
5226 if (!has_more_regions(dest)) {
5227 return NULL;
5228 }
5229
5230 const bool is_survivor = dest.is_young();
5231
5232 HeapRegion* new_alloc_region = new_region(word_size,
5233 !is_survivor,
5234 true /* do_expand */);
5235 if (new_alloc_region != NULL) {
5236 // We really only need to do this for old regions given that we
5237 // should never scan survivors. But it doesn't hurt to do it
5238 // for survivors too.
5239 new_alloc_region->record_timestamp();
5240 if (is_survivor) {
5241 new_alloc_region->set_survivor();
5242 _survivor.add(new_alloc_region);
5243 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5244 } else {
5245 new_alloc_region->set_old();
5246 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5247 }
5248 _hr_printer.alloc(new_alloc_region);
5249 bool during_im = collector_state()->during_initial_mark_pause();
5250 new_alloc_region->note_start_of_copying(during_im);
5251 return new_alloc_region;
5252 }
5253 return NULL;
5254 }
5255
5256 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5257 size_t allocated_bytes,
5258 InCSetState dest) {
5259 bool during_im = collector_state()->during_initial_mark_pause();
5260 alloc_region->note_end_of_copying(during_im);
5261 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5262 if (dest.is_old()) {
5263 _old_set.add(alloc_region);
5264 }
5265 _hr_printer.retire(alloc_region);
5266 }
5267
5268 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5269 bool expanded = false;
5270 uint index = _hrm.find_highest_free(&expanded);
5271
5272 if (index != G1_NO_HRM_INDEX) {
5273 if (expanded) {
5274 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5275 HeapRegion::GrainWords * HeapWordSize);
5276 }
5277 _hrm.allocate_free_regions_starting_at(index, 1);
5278 return region_at(index);
5279 }
5280 return NULL;
5281 }
5282
5283 // Optimized nmethod scanning
5284
5285 class RegisterNMethodOopClosure: public OopClosure {
5286 G1CollectedHeap* _g1h;
5287 nmethod* _nm;
5288
5289 template <class T> void do_oop_work(T* p) {
5290 T heap_oop = oopDesc::load_heap_oop(p);
5291 if (!oopDesc::is_null(heap_oop)) {
5292 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5293 HeapRegion* hr = _g1h->heap_region_containing(obj);
5294 assert(!hr->is_continues_humongous(),
5295 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5296 " starting at " HR_FORMAT,
5297 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5298
5299 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5300 hr->add_strong_code_root_locked(_nm);
5301 }
5302 }
5303
5304 public:
5305 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5306 _g1h(g1h), _nm(nm) {}
5307
5308 void do_oop(oop* p) { do_oop_work(p); }
5309 void do_oop(narrowOop* p) { do_oop_work(p); }
5310 };
5311
5312 class UnregisterNMethodOopClosure: public OopClosure {
5313 G1CollectedHeap* _g1h;
5314 nmethod* _nm;
5315
5316 template <class T> void do_oop_work(T* p) {
5317 T heap_oop = oopDesc::load_heap_oop(p);
5318 if (!oopDesc::is_null(heap_oop)) {
5319 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5320 HeapRegion* hr = _g1h->heap_region_containing(obj);
5321 assert(!hr->is_continues_humongous(),
5322 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5323 " starting at " HR_FORMAT,
5324 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5325
5326 hr->remove_strong_code_root(_nm);
5327 }
5328 }
5329
5330 public:
5331 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5332 _g1h(g1h), _nm(nm) {}
5333
5334 void do_oop(oop* p) { do_oop_work(p); }
5335 void do_oop(narrowOop* p) { do_oop_work(p); }
5336 };
5337
5338 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5339 CollectedHeap::register_nmethod(nm);
5340
5341 guarantee(nm != NULL, "sanity");
5342 RegisterNMethodOopClosure reg_cl(this, nm);
5343 nm->oops_do(®_cl);
5344 }
5345
5346 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5347 CollectedHeap::unregister_nmethod(nm);
5348
5349 guarantee(nm != NULL, "sanity");
5350 UnregisterNMethodOopClosure reg_cl(this, nm);
5351 nm->oops_do(®_cl, true);
5352 }
5353
5354 void G1CollectedHeap::purge_code_root_memory() {
5355 double purge_start = os::elapsedTime();
5356 G1CodeRootSet::purge();
5357 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5358 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5359 }
5360
5361 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5362 G1CollectedHeap* _g1h;
5363
5364 public:
5365 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5366 _g1h(g1h) {}
5367
5368 void do_code_blob(CodeBlob* cb) {
5369 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5370 if (nm == NULL) {
5371 return;
5372 }
5373
5374 if (ScavengeRootsInCode) {
5375 _g1h->register_nmethod(nm);
5376 }
5377 }
5378 };
5379
5380 void G1CollectedHeap::rebuild_strong_code_roots() {
5381 RebuildStrongCodeRootClosure blob_cl(this);
5382 CodeCache::blobs_do(&blob_cl);
5383 }