1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectorPolicy.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1GCPhaseTimes.hpp"
42 #include "gc/g1/g1HeapSizingPolicy.hpp"
43 #include "gc/g1/g1HeapTransition.hpp"
44 #include "gc/g1/g1HeapVerifier.hpp"
45 #include "gc/g1/g1HotCardCache.hpp"
46 #include "gc/g1/g1MarkSweep.hpp"
47 #include "gc/g1/g1OopClosures.inline.hpp"
48 #include "gc/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc/g1/g1Policy.hpp"
50 #include "gc/g1/g1RegionToSpaceMapper.hpp"
51 #include "gc/g1/g1RemSet.inline.hpp"
52 #include "gc/g1/g1RootClosures.hpp"
53 #include "gc/g1/g1RootProcessor.hpp"
54 #include "gc/g1/g1StringDedup.hpp"
55 #include "gc/g1/g1YCTypes.hpp"
56 #include "gc/g1/heapRegion.inline.hpp"
57 #include "gc/g1/heapRegionRemSet.hpp"
58 #include "gc/g1/heapRegionSet.inline.hpp"
59 #include "gc/g1/suspendibleThreadSet.hpp"
60 #include "gc/g1/vm_operations_g1.hpp"
61 #include "gc/shared/gcHeapSummary.hpp"
62 #include "gc/shared/gcId.hpp"
63 #include "gc/shared/gcLocker.inline.hpp"
64 #include "gc/shared/gcTimer.hpp"
65 #include "gc/shared/gcTrace.hpp"
66 #include "gc/shared/gcTraceTime.inline.hpp"
67 #include "gc/shared/generationSpec.hpp"
68 #include "gc/shared/isGCActiveMark.hpp"
69 #include "gc/shared/preservedMarks.inline.hpp"
70 #include "gc/shared/referenceProcessor.inline.hpp"
71 #include "gc/shared/taskqueue.inline.hpp"
72 #include "logging/log.hpp"
73 #include "memory/allocation.hpp"
74 #include "memory/iterator.hpp"
75 #include "memory/resourceArea.hpp"
76 #include "oops/oop.inline.hpp"
77 #include "prims/resolvedMethodTable.hpp"
78 #include "runtime/atomic.hpp"
79 #include "runtime/init.hpp"
80 #include "runtime/orderAccess.inline.hpp"
81 #include "runtime/vmThread.hpp"
82 #include "utilities/globalDefinitions.hpp"
83 #include "utilities/stack.inline.hpp"
84
85 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
86
87 // INVARIANTS/NOTES
88 //
89 // All allocation activity covered by the G1CollectedHeap interface is
90 // serialized by acquiring the HeapLock. This happens in mem_allocate
91 // and allocate_new_tlab, which are the "entry" points to the
92 // allocation code from the rest of the JVM. (Note that this does not
93 // apply to TLAB allocation, which is not part of this interface: it
94 // is done by clients of this interface.)
95
96 // Local to this file.
97
98 class RefineCardTableEntryClosure: public CardTableEntryClosure {
99 bool _concurrent;
100 public:
101 RefineCardTableEntryClosure() : _concurrent(true) { }
102
103 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
104 G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_dirtied;
121 G1CollectedHeap* _g1h;
122 G1SATBCardTableLoggingModRefBS* _g1_bs;
123
124 HeapRegion* region_for_card(jbyte* card_ptr) const {
125 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
126 }
127
128 bool will_become_free(HeapRegion* hr) const {
129 // A region will be freed by free_collection_set if the region is in the
130 // collection set and has not had an evacuation failure.
131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
132 }
133
134 public:
135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
136 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
137
138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
139 HeapRegion* hr = region_for_card(card_ptr);
140
141 // Should only dirty cards in regions that won't be freed.
142 if (!will_become_free(hr)) {
143 *card_ptr = CardTableModRefBS::dirty_card_val();
144 _num_dirtied++;
145 }
146
147 return true;
148 }
149
150 size_t num_dirtied() const { return _num_dirtied; }
151 };
152
153
154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
156 }
157
158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
159 // The from card cache is not the memory that is actually committed. So we cannot
160 // take advantage of the zero_filled parameter.
161 reset_from_card_cache(start_idx, num_regions);
162 }
163
164 // Returns true if the reference points to an object that
165 // can move in an incremental collection.
166 bool G1CollectedHeap::is_scavengable(const void* p) {
167 HeapRegion* hr = heap_region_containing(p);
168 return !hr->is_pinned();
169 }
170
171 // Private methods.
172
173 HeapRegion*
174 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
175 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
176 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
177 if (!_secondary_free_list.is_empty()) {
178 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
179 "secondary_free_list has %u entries",
180 _secondary_free_list.length());
181 // It looks as if there are free regions available on the
182 // secondary_free_list. Let's move them to the free_list and try
183 // again to allocate from it.
184 append_secondary_free_list();
185
186 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
187 "empty we should have moved at least one entry to the free_list");
188 HeapRegion* res = _hrm.allocate_free_region(is_old);
189 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
190 "allocated " HR_FORMAT " from secondary_free_list",
191 HR_FORMAT_PARAMS(res));
192 return res;
193 }
194
195 // Wait here until we get notified either when (a) there are no
196 // more free regions coming or (b) some regions have been moved on
197 // the secondary_free_list.
198 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
199 }
200
201 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
202 "could not allocate from secondary_free_list");
203 return NULL;
204 }
205
206 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
207 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
208 "the only time we use this to allocate a humongous region is "
209 "when we are allocating a single humongous region");
210
211 HeapRegion* res;
212 if (G1StressConcRegionFreeing) {
213 if (!_secondary_free_list.is_empty()) {
214 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
215 "forced to look at the secondary_free_list");
216 res = new_region_try_secondary_free_list(is_old);
217 if (res != NULL) {
218 return res;
219 }
220 }
221 }
222
223 res = _hrm.allocate_free_region(is_old);
224
225 if (res == NULL) {
226 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
227 "res == NULL, trying the secondary_free_list");
228 res = new_region_try_secondary_free_list(is_old);
229 }
230 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
231 // Currently, only attempts to allocate GC alloc regions set
232 // do_expand to true. So, we should only reach here during a
233 // safepoint. If this assumption changes we might have to
234 // reconsider the use of _expand_heap_after_alloc_failure.
235 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
236
237 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
238 word_size * HeapWordSize);
239
240 if (expand(word_size * HeapWordSize)) {
241 // Given that expand() succeeded in expanding the heap, and we
242 // always expand the heap by an amount aligned to the heap
243 // region size, the free list should in theory not be empty.
244 // In either case allocate_free_region() will check for NULL.
245 res = _hrm.allocate_free_region(is_old);
246 } else {
247 _expand_heap_after_alloc_failure = false;
248 }
249 }
250 return res;
251 }
252
253 HeapWord*
254 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
255 uint num_regions,
256 size_t word_size,
257 AllocationContext_t context) {
258 assert(first != G1_NO_HRM_INDEX, "pre-condition");
259 assert(is_humongous(word_size), "word_size should be humongous");
260 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
261
262 // Index of last region in the series.
263 uint last = first + num_regions - 1;
264
265 // We need to initialize the region(s) we just discovered. This is
266 // a bit tricky given that it can happen concurrently with
267 // refinement threads refining cards on these regions and
268 // potentially wanting to refine the BOT as they are scanning
269 // those cards (this can happen shortly after a cleanup; see CR
270 // 6991377). So we have to set up the region(s) carefully and in
271 // a specific order.
272
273 // The word size sum of all the regions we will allocate.
274 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
275 assert(word_size <= word_size_sum, "sanity");
276
277 // This will be the "starts humongous" region.
278 HeapRegion* first_hr = region_at(first);
279 // The header of the new object will be placed at the bottom of
280 // the first region.
281 HeapWord* new_obj = first_hr->bottom();
282 // This will be the new top of the new object.
283 HeapWord* obj_top = new_obj + word_size;
284
285 // First, we need to zero the header of the space that we will be
286 // allocating. When we update top further down, some refinement
287 // threads might try to scan the region. By zeroing the header we
288 // ensure that any thread that will try to scan the region will
289 // come across the zero klass word and bail out.
290 //
291 // NOTE: It would not have been correct to have used
292 // CollectedHeap::fill_with_object() and make the space look like
293 // an int array. The thread that is doing the allocation will
294 // later update the object header to a potentially different array
295 // type and, for a very short period of time, the klass and length
296 // fields will be inconsistent. This could cause a refinement
297 // thread to calculate the object size incorrectly.
298 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
299
300 // Next, pad out the unused tail of the last region with filler
301 // objects, for improved usage accounting.
302 // How many words we use for filler objects.
303 size_t word_fill_size = word_size_sum - word_size;
304
305 // How many words memory we "waste" which cannot hold a filler object.
306 size_t words_not_fillable = 0;
307
308 if (word_fill_size >= min_fill_size()) {
309 fill_with_objects(obj_top, word_fill_size);
310 } else if (word_fill_size > 0) {
311 // We have space to fill, but we cannot fit an object there.
312 words_not_fillable = word_fill_size;
313 word_fill_size = 0;
314 }
315
316 // We will set up the first region as "starts humongous". This
317 // will also update the BOT covering all the regions to reflect
318 // that there is a single object that starts at the bottom of the
319 // first region.
320 first_hr->set_starts_humongous(obj_top, word_fill_size);
321 first_hr->set_allocation_context(context);
322 // Then, if there are any, we will set up the "continues
323 // humongous" regions.
324 HeapRegion* hr = NULL;
325 for (uint i = first + 1; i <= last; ++i) {
326 hr = region_at(i);
327 hr->set_continues_humongous(first_hr);
328 hr->set_allocation_context(context);
329 }
330
331 // Up to this point no concurrent thread would have been able to
332 // do any scanning on any region in this series. All the top
333 // fields still point to bottom, so the intersection between
334 // [bottom,top] and [card_start,card_end] will be empty. Before we
335 // update the top fields, we'll do a storestore to make sure that
336 // no thread sees the update to top before the zeroing of the
337 // object header and the BOT initialization.
338 OrderAccess::storestore();
339
340 // Now, we will update the top fields of the "continues humongous"
341 // regions except the last one.
342 for (uint i = first; i < last; ++i) {
343 hr = region_at(i);
344 hr->set_top(hr->end());
345 }
346
347 hr = region_at(last);
348 // If we cannot fit a filler object, we must set top to the end
349 // of the humongous object, otherwise we cannot iterate the heap
350 // and the BOT will not be complete.
351 hr->set_top(hr->end() - words_not_fillable);
352
353 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
354 "obj_top should be in last region");
355
356 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
357
358 assert(words_not_fillable == 0 ||
359 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
360 "Miscalculation in humongous allocation");
361
362 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
363
364 for (uint i = first; i <= last; ++i) {
365 hr = region_at(i);
366 _humongous_set.add(hr);
367 _hr_printer.alloc(hr);
368 }
369
370 return new_obj;
371 }
372
373 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
374 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
375 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
376 }
377
378 // If could fit into free regions w/o expansion, try.
379 // Otherwise, if can expand, do so.
380 // Otherwise, if using ex regions might help, try with ex given back.
381 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
382 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
383
384 _verifier->verify_region_sets_optional();
385
386 uint first = G1_NO_HRM_INDEX;
387 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
388
389 if (obj_regions == 1) {
390 // Only one region to allocate, try to use a fast path by directly allocating
391 // from the free lists. Do not try to expand here, we will potentially do that
392 // later.
393 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
394 if (hr != NULL) {
395 first = hr->hrm_index();
396 }
397 } else {
398 // We can't allocate humongous regions spanning more than one region while
399 // cleanupComplete() is running, since some of the regions we find to be
400 // empty might not yet be added to the free list. It is not straightforward
401 // to know in which list they are on so that we can remove them. We only
402 // need to do this if we need to allocate more than one region to satisfy the
403 // current humongous allocation request. If we are only allocating one region
404 // we use the one-region region allocation code (see above), that already
405 // potentially waits for regions from the secondary free list.
406 wait_while_free_regions_coming();
407 append_secondary_free_list_if_not_empty_with_lock();
408
409 // Policy: Try only empty regions (i.e. already committed first). Maybe we
410 // are lucky enough to find some.
411 first = _hrm.find_contiguous_only_empty(obj_regions);
412 if (first != G1_NO_HRM_INDEX) {
413 _hrm.allocate_free_regions_starting_at(first, obj_regions);
414 }
415 }
416
417 if (first == G1_NO_HRM_INDEX) {
418 // Policy: We could not find enough regions for the humongous object in the
419 // free list. Look through the heap to find a mix of free and uncommitted regions.
420 // If so, try expansion.
421 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
422 if (first != G1_NO_HRM_INDEX) {
423 // We found something. Make sure these regions are committed, i.e. expand
424 // the heap. Alternatively we could do a defragmentation GC.
425 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
426 word_size * HeapWordSize);
427
428 _hrm.expand_at(first, obj_regions, workers());
429 g1_policy()->record_new_heap_size(num_regions());
430
431 #ifdef ASSERT
432 for (uint i = first; i < first + obj_regions; ++i) {
433 HeapRegion* hr = region_at(i);
434 assert(hr->is_free(), "sanity");
435 assert(hr->is_empty(), "sanity");
436 assert(is_on_master_free_list(hr), "sanity");
437 }
438 #endif
439 _hrm.allocate_free_regions_starting_at(first, obj_regions);
440 } else {
441 // Policy: Potentially trigger a defragmentation GC.
442 }
443 }
444
445 HeapWord* result = NULL;
446 if (first != G1_NO_HRM_INDEX) {
447 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
448 word_size, context);
449 assert(result != NULL, "it should always return a valid result");
450
451 // A successful humongous object allocation changes the used space
452 // information of the old generation so we need to recalculate the
453 // sizes and update the jstat counters here.
454 g1mm()->update_sizes();
455 }
456
457 _verifier->verify_region_sets_optional();
458
459 return result;
460 }
461
462 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
463 assert_heap_not_locked_and_not_at_safepoint();
464 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
465
466 uint dummy_gc_count_before;
467 uint dummy_gclocker_retry_count = 0;
468 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
469 }
470
471 HeapWord*
472 G1CollectedHeap::mem_allocate(size_t word_size,
473 bool* gc_overhead_limit_was_exceeded) {
474 assert_heap_not_locked_and_not_at_safepoint();
475
476 // Loop until the allocation is satisfied, or unsatisfied after GC.
477 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
478 uint gc_count_before;
479
480 HeapWord* result = NULL;
481 if (!is_humongous(word_size)) {
482 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
483 } else {
484 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
485 }
486 if (result != NULL) {
487 return result;
488 }
489
490 // Create the garbage collection operation...
491 VM_G1CollectForAllocation op(gc_count_before, word_size);
492 op.set_allocation_context(AllocationContext::current());
493
494 // ...and get the VM thread to execute it.
495 VMThread::execute(&op);
496
497 if (op.prologue_succeeded() && op.pause_succeeded()) {
498 // If the operation was successful we'll return the result even
499 // if it is NULL. If the allocation attempt failed immediately
500 // after a Full GC, it's unlikely we'll be able to allocate now.
501 HeapWord* result = op.result();
502 if (result != NULL && !is_humongous(word_size)) {
503 // Allocations that take place on VM operations do not do any
504 // card dirtying and we have to do it here. We only have to do
505 // this for non-humongous allocations, though.
506 dirty_young_block(result, word_size);
507 }
508 return result;
509 } else {
510 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
511 return NULL;
512 }
513 assert(op.result() == NULL,
514 "the result should be NULL if the VM op did not succeed");
515 }
516
517 // Give a warning if we seem to be looping forever.
518 if ((QueuedAllocationWarningCount > 0) &&
519 (try_count % QueuedAllocationWarningCount == 0)) {
520 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
521 }
522 }
523
524 ShouldNotReachHere();
525 return NULL;
526 }
527
528 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
529 AllocationContext_t context,
530 uint* gc_count_before_ret,
531 uint* gclocker_retry_count_ret) {
532 // Make sure you read the note in attempt_allocation_humongous().
533
534 assert_heap_not_locked_and_not_at_safepoint();
535 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
536 "be called for humongous allocation requests");
537
538 // We should only get here after the first-level allocation attempt
539 // (attempt_allocation()) failed to allocate.
540
541 // We will loop until a) we manage to successfully perform the
542 // allocation or b) we successfully schedule a collection which
543 // fails to perform the allocation. b) is the only case when we'll
544 // return NULL.
545 HeapWord* result = NULL;
546 for (int try_count = 1; /* we'll return */; try_count += 1) {
547 bool should_try_gc;
548 uint gc_count_before;
549
550 {
551 MutexLockerEx x(Heap_lock);
552 result = _allocator->attempt_allocation_locked(word_size, context);
553 if (result != NULL) {
554 return result;
555 }
556
557 if (GCLocker::is_active_and_needs_gc()) {
558 if (g1_policy()->can_expand_young_list()) {
559 // No need for an ergo verbose message here,
560 // can_expand_young_list() does this when it returns true.
561 result = _allocator->attempt_allocation_force(word_size, context);
562 if (result != NULL) {
563 return result;
564 }
565 }
566 should_try_gc = false;
567 } else {
568 // The GCLocker may not be active but the GCLocker initiated
569 // GC may not yet have been performed (GCLocker::needs_gc()
570 // returns true). In this case we do not try this GC and
571 // wait until the GCLocker initiated GC is performed, and
572 // then retry the allocation.
573 if (GCLocker::needs_gc()) {
574 should_try_gc = false;
575 } else {
576 // Read the GC count while still holding the Heap_lock.
577 gc_count_before = total_collections();
578 should_try_gc = true;
579 }
580 }
581 }
582
583 if (should_try_gc) {
584 bool succeeded;
585 result = do_collection_pause(word_size, gc_count_before, &succeeded,
586 GCCause::_g1_inc_collection_pause);
587 if (result != NULL) {
588 assert(succeeded, "only way to get back a non-NULL result");
589 return result;
590 }
591
592 if (succeeded) {
593 // If we get here we successfully scheduled a collection which
594 // failed to allocate. No point in trying to allocate
595 // further. We'll just return NULL.
596 MutexLockerEx x(Heap_lock);
597 *gc_count_before_ret = total_collections();
598 return NULL;
599 }
600 } else {
601 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
602 MutexLockerEx x(Heap_lock);
603 *gc_count_before_ret = total_collections();
604 return NULL;
605 }
606 // The GCLocker is either active or the GCLocker initiated
607 // GC has not yet been performed. Stall until it is and
608 // then retry the allocation.
609 GCLocker::stall_until_clear();
610 (*gclocker_retry_count_ret) += 1;
611 }
612
613 // We can reach here if we were unsuccessful in scheduling a
614 // collection (because another thread beat us to it) or if we were
615 // stalled due to the GC locker. In either can we should retry the
616 // allocation attempt in case another thread successfully
617 // performed a collection and reclaimed enough space. We do the
618 // first attempt (without holding the Heap_lock) here and the
619 // follow-on attempt will be at the start of the next loop
620 // iteration (after taking the Heap_lock).
621 result = _allocator->attempt_allocation(word_size, context);
622 if (result != NULL) {
623 return result;
624 }
625
626 // Give a warning if we seem to be looping forever.
627 if ((QueuedAllocationWarningCount > 0) &&
628 (try_count % QueuedAllocationWarningCount == 0)) {
629 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
630 "retries %d times", try_count);
631 }
632 }
633
634 ShouldNotReachHere();
635 return NULL;
636 }
637
638 void G1CollectedHeap::begin_archive_alloc_range() {
639 assert_at_safepoint(true /* should_be_vm_thread */);
640 if (_archive_allocator == NULL) {
641 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
642 }
643 }
644
645 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
646 // Allocations in archive regions cannot be of a size that would be considered
647 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
648 // may be different at archive-restore time.
649 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
650 }
651
652 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
653 assert_at_safepoint(true /* should_be_vm_thread */);
654 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
655 if (is_archive_alloc_too_large(word_size)) {
656 return NULL;
657 }
658 return _archive_allocator->archive_mem_allocate(word_size);
659 }
660
661 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
662 size_t end_alignment_in_bytes) {
663 assert_at_safepoint(true /* should_be_vm_thread */);
664 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
665
666 // Call complete_archive to do the real work, filling in the MemRegion
667 // array with the archive regions.
668 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
669 delete _archive_allocator;
670 _archive_allocator = NULL;
671 }
672
673 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
674 assert(ranges != NULL, "MemRegion array NULL");
675 assert(count != 0, "No MemRegions provided");
676 MemRegion reserved = _hrm.reserved();
677 for (size_t i = 0; i < count; i++) {
678 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
679 return false;
680 }
681 }
682 return true;
683 }
684
685 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
686 assert(!is_init_completed(), "Expect to be called at JVM init time");
687 assert(ranges != NULL, "MemRegion array NULL");
688 assert(count != 0, "No MemRegions provided");
689 MutexLockerEx x(Heap_lock);
690
691 MemRegion reserved = _hrm.reserved();
692 HeapWord* prev_last_addr = NULL;
693 HeapRegion* prev_last_region = NULL;
694
695 // Temporarily disable pretouching of heap pages. This interface is used
696 // when mmap'ing archived heap data in, so pre-touching is wasted.
697 FlagSetting fs(AlwaysPreTouch, false);
698
699 // Enable archive object checking used by G1MarkSweep. We have to let it know
700 // about each archive range, so that objects in those ranges aren't marked.
701 G1ArchiveAllocator::enable_archive_object_check();
702
703 // For each specified MemRegion range, allocate the corresponding G1
704 // regions and mark them as archive regions. We expect the ranges in
705 // ascending starting address order, without overlap.
706 for (size_t i = 0; i < count; i++) {
707 MemRegion curr_range = ranges[i];
708 HeapWord* start_address = curr_range.start();
709 size_t word_size = curr_range.word_size();
710 HeapWord* last_address = curr_range.last();
711 size_t commits = 0;
712
713 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
714 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
715 p2i(start_address), p2i(last_address));
716 guarantee(start_address > prev_last_addr,
717 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
718 p2i(start_address), p2i(prev_last_addr));
719 prev_last_addr = last_address;
720
721 // Check for ranges that start in the same G1 region in which the previous
722 // range ended, and adjust the start address so we don't try to allocate
723 // the same region again. If the current range is entirely within that
724 // region, skip it, just adjusting the recorded top.
725 HeapRegion* start_region = _hrm.addr_to_region(start_address);
726 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
727 start_address = start_region->end();
728 if (start_address > last_address) {
729 increase_used(word_size * HeapWordSize);
730 start_region->set_top(last_address + 1);
731 continue;
732 }
733 start_region->set_top(start_address);
734 curr_range = MemRegion(start_address, last_address + 1);
735 start_region = _hrm.addr_to_region(start_address);
736 }
737
738 // Perform the actual region allocation, exiting if it fails.
739 // Then note how much new space we have allocated.
740 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
741 return false;
742 }
743 increase_used(word_size * HeapWordSize);
744 if (commits != 0) {
745 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
746 HeapRegion::GrainWords * HeapWordSize * commits);
747
748 }
749
750 // Mark each G1 region touched by the range as archive, add it to the old set,
751 // and set the allocation context and top.
752 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
753 HeapRegion* last_region = _hrm.addr_to_region(last_address);
754 prev_last_region = last_region;
755
756 while (curr_region != NULL) {
757 assert(curr_region->is_empty() && !curr_region->is_pinned(),
758 "Region already in use (index %u)", curr_region->hrm_index());
759 curr_region->set_allocation_context(AllocationContext::system());
760 curr_region->set_archive();
761 _hr_printer.alloc(curr_region);
762 _old_set.add(curr_region);
763 if (curr_region != last_region) {
764 curr_region->set_top(curr_region->end());
765 curr_region = _hrm.next_region_in_heap(curr_region);
766 } else {
767 curr_region->set_top(last_address + 1);
768 curr_region = NULL;
769 }
770 }
771
772 // Notify mark-sweep of the archive range.
773 G1ArchiveAllocator::set_range_archive(curr_range, true);
774 }
775 return true;
776 }
777
778 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
779 assert(!is_init_completed(), "Expect to be called at JVM init time");
780 assert(ranges != NULL, "MemRegion array NULL");
781 assert(count != 0, "No MemRegions provided");
782 MemRegion reserved = _hrm.reserved();
783 HeapWord *prev_last_addr = NULL;
784 HeapRegion* prev_last_region = NULL;
785
786 // For each MemRegion, create filler objects, if needed, in the G1 regions
787 // that contain the address range. The address range actually within the
788 // MemRegion will not be modified. That is assumed to have been initialized
789 // elsewhere, probably via an mmap of archived heap data.
790 MutexLockerEx x(Heap_lock);
791 for (size_t i = 0; i < count; i++) {
792 HeapWord* start_address = ranges[i].start();
793 HeapWord* last_address = ranges[i].last();
794
795 assert(reserved.contains(start_address) && reserved.contains(last_address),
796 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
797 p2i(start_address), p2i(last_address));
798 assert(start_address > prev_last_addr,
799 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
800 p2i(start_address), p2i(prev_last_addr));
801
802 HeapRegion* start_region = _hrm.addr_to_region(start_address);
803 HeapRegion* last_region = _hrm.addr_to_region(last_address);
804 HeapWord* bottom_address = start_region->bottom();
805
806 // Check for a range beginning in the same region in which the
807 // previous one ended.
808 if (start_region == prev_last_region) {
809 bottom_address = prev_last_addr + 1;
810 }
811
812 // Verify that the regions were all marked as archive regions by
813 // alloc_archive_regions.
814 HeapRegion* curr_region = start_region;
815 while (curr_region != NULL) {
816 guarantee(curr_region->is_archive(),
817 "Expected archive region at index %u", curr_region->hrm_index());
818 if (curr_region != last_region) {
819 curr_region = _hrm.next_region_in_heap(curr_region);
820 } else {
821 curr_region = NULL;
822 }
823 }
824
825 prev_last_addr = last_address;
826 prev_last_region = last_region;
827
828 // Fill the memory below the allocated range with dummy object(s),
829 // if the region bottom does not match the range start, or if the previous
830 // range ended within the same G1 region, and there is a gap.
831 if (start_address != bottom_address) {
832 size_t fill_size = pointer_delta(start_address, bottom_address);
833 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
834 increase_used(fill_size * HeapWordSize);
835 }
836 }
837 }
838
839 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
840 uint* gc_count_before_ret,
841 uint* gclocker_retry_count_ret) {
842 assert_heap_not_locked_and_not_at_safepoint();
843 assert(!is_humongous(word_size), "attempt_allocation() should not "
844 "be called for humongous allocation requests");
845
846 AllocationContext_t context = AllocationContext::current();
847 HeapWord* result = _allocator->attempt_allocation(word_size, context);
848
849 if (result == NULL) {
850 result = attempt_allocation_slow(word_size,
851 context,
852 gc_count_before_ret,
853 gclocker_retry_count_ret);
854 }
855 assert_heap_not_locked();
856 if (result != NULL) {
857 dirty_young_block(result, word_size);
858 }
859 return result;
860 }
861
862 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
863 assert(!is_init_completed(), "Expect to be called at JVM init time");
864 assert(ranges != NULL, "MemRegion array NULL");
865 assert(count != 0, "No MemRegions provided");
866 MemRegion reserved = _hrm.reserved();
867 HeapWord* prev_last_addr = NULL;
868 HeapRegion* prev_last_region = NULL;
869 size_t size_used = 0;
870 size_t uncommitted_regions = 0;
871
872 // For each Memregion, free the G1 regions that constitute it, and
873 // notify mark-sweep that the range is no longer to be considered 'archive.'
874 MutexLockerEx x(Heap_lock);
875 for (size_t i = 0; i < count; i++) {
876 HeapWord* start_address = ranges[i].start();
877 HeapWord* last_address = ranges[i].last();
878
879 assert(reserved.contains(start_address) && reserved.contains(last_address),
880 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
881 p2i(start_address), p2i(last_address));
882 assert(start_address > prev_last_addr,
883 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
884 p2i(start_address), p2i(prev_last_addr));
885 size_used += ranges[i].byte_size();
886 prev_last_addr = last_address;
887
888 HeapRegion* start_region = _hrm.addr_to_region(start_address);
889 HeapRegion* last_region = _hrm.addr_to_region(last_address);
890
891 // Check for ranges that start in the same G1 region in which the previous
892 // range ended, and adjust the start address so we don't try to free
893 // the same region again. If the current range is entirely within that
894 // region, skip it.
895 if (start_region == prev_last_region) {
896 start_address = start_region->end();
897 if (start_address > last_address) {
898 continue;
899 }
900 start_region = _hrm.addr_to_region(start_address);
901 }
902 prev_last_region = last_region;
903
904 // After verifying that each region was marked as an archive region by
905 // alloc_archive_regions, set it free and empty and uncommit it.
906 HeapRegion* curr_region = start_region;
907 while (curr_region != NULL) {
908 guarantee(curr_region->is_archive(),
909 "Expected archive region at index %u", curr_region->hrm_index());
910 uint curr_index = curr_region->hrm_index();
911 _old_set.remove(curr_region);
912 curr_region->set_free();
913 curr_region->set_top(curr_region->bottom());
914 if (curr_region != last_region) {
915 curr_region = _hrm.next_region_in_heap(curr_region);
916 } else {
917 curr_region = NULL;
918 }
919 _hrm.shrink_at(curr_index, 1);
920 uncommitted_regions++;
921 }
922
923 // Notify mark-sweep that this is no longer an archive range.
924 G1ArchiveAllocator::set_range_archive(ranges[i], false);
925 }
926
927 if (uncommitted_regions != 0) {
928 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
929 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
930 }
931 decrease_used(size_used);
932 }
933
934 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
935 uint* gc_count_before_ret,
936 uint* gclocker_retry_count_ret) {
937 // The structure of this method has a lot of similarities to
938 // attempt_allocation_slow(). The reason these two were not merged
939 // into a single one is that such a method would require several "if
940 // allocation is not humongous do this, otherwise do that"
941 // conditional paths which would obscure its flow. In fact, an early
942 // version of this code did use a unified method which was harder to
943 // follow and, as a result, it had subtle bugs that were hard to
944 // track down. So keeping these two methods separate allows each to
945 // be more readable. It will be good to keep these two in sync as
946 // much as possible.
947
948 assert_heap_not_locked_and_not_at_safepoint();
949 assert(is_humongous(word_size), "attempt_allocation_humongous() "
950 "should only be called for humongous allocations");
951
952 // Humongous objects can exhaust the heap quickly, so we should check if we
953 // need to start a marking cycle at each humongous object allocation. We do
954 // the check before we do the actual allocation. The reason for doing it
955 // before the allocation is that we avoid having to keep track of the newly
956 // allocated memory while we do a GC.
957 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
958 word_size)) {
959 collect(GCCause::_g1_humongous_allocation);
960 }
961
962 // We will loop until a) we manage to successfully perform the
963 // allocation or b) we successfully schedule a collection which
964 // fails to perform the allocation. b) is the only case when we'll
965 // return NULL.
966 HeapWord* result = NULL;
967 for (int try_count = 1; /* we'll return */; try_count += 1) {
968 bool should_try_gc;
969 uint gc_count_before;
970
971 {
972 MutexLockerEx x(Heap_lock);
973
974 // Given that humongous objects are not allocated in young
975 // regions, we'll first try to do the allocation without doing a
976 // collection hoping that there's enough space in the heap.
977 result = humongous_obj_allocate(word_size, AllocationContext::current());
978 if (result != NULL) {
979 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
980 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
981 return result;
982 }
983
984 if (GCLocker::is_active_and_needs_gc()) {
985 should_try_gc = false;
986 } else {
987 // The GCLocker may not be active but the GCLocker initiated
988 // GC may not yet have been performed (GCLocker::needs_gc()
989 // returns true). In this case we do not try this GC and
990 // wait until the GCLocker initiated GC is performed, and
991 // then retry the allocation.
992 if (GCLocker::needs_gc()) {
993 should_try_gc = false;
994 } else {
995 // Read the GC count while still holding the Heap_lock.
996 gc_count_before = total_collections();
997 should_try_gc = true;
998 }
999 }
1000 }
1001
1002 if (should_try_gc) {
1003 // If we failed to allocate the humongous object, we should try to
1004 // do a collection pause (if we're allowed) in case it reclaims
1005 // enough space for the allocation to succeed after the pause.
1006
1007 bool succeeded;
1008 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1009 GCCause::_g1_humongous_allocation);
1010 if (result != NULL) {
1011 assert(succeeded, "only way to get back a non-NULL result");
1012 return result;
1013 }
1014
1015 if (succeeded) {
1016 // If we get here we successfully scheduled a collection which
1017 // failed to allocate. No point in trying to allocate
1018 // further. We'll just return NULL.
1019 MutexLockerEx x(Heap_lock);
1020 *gc_count_before_ret = total_collections();
1021 return NULL;
1022 }
1023 } else {
1024 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1025 MutexLockerEx x(Heap_lock);
1026 *gc_count_before_ret = total_collections();
1027 return NULL;
1028 }
1029 // The GCLocker is either active or the GCLocker initiated
1030 // GC has not yet been performed. Stall until it is and
1031 // then retry the allocation.
1032 GCLocker::stall_until_clear();
1033 (*gclocker_retry_count_ret) += 1;
1034 }
1035
1036 // We can reach here if we were unsuccessful in scheduling a
1037 // collection (because another thread beat us to it) or if we were
1038 // stalled due to the GC locker. In either can we should retry the
1039 // allocation attempt in case another thread successfully
1040 // performed a collection and reclaimed enough space. Give a
1041 // warning if we seem to be looping forever.
1042
1043 if ((QueuedAllocationWarningCount > 0) &&
1044 (try_count % QueuedAllocationWarningCount == 0)) {
1045 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1046 "retries %d times", try_count);
1047 }
1048 }
1049
1050 ShouldNotReachHere();
1051 return NULL;
1052 }
1053
1054 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1055 AllocationContext_t context,
1056 bool expect_null_mutator_alloc_region) {
1057 assert_at_safepoint(true /* should_be_vm_thread */);
1058 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1059 "the current alloc region was unexpectedly found to be non-NULL");
1060
1061 if (!is_humongous(word_size)) {
1062 return _allocator->attempt_allocation_locked(word_size, context);
1063 } else {
1064 HeapWord* result = humongous_obj_allocate(word_size, context);
1065 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1066 collector_state()->set_initiate_conc_mark_if_possible(true);
1067 }
1068 return result;
1069 }
1070
1071 ShouldNotReachHere();
1072 }
1073
1074 class PostMCRemSetClearClosure: public HeapRegionClosure {
1075 G1CollectedHeap* _g1h;
1076 ModRefBarrierSet* _mr_bs;
1077 public:
1078 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1079 _g1h(g1h), _mr_bs(mr_bs) {}
1080
1081 bool doHeapRegion(HeapRegion* r) {
1082 HeapRegionRemSet* hrrs = r->rem_set();
1083
1084 _g1h->reset_gc_time_stamps(r);
1085
1086 if (r->is_continues_humongous()) {
1087 // We'll assert that the strong code root list and RSet is empty
1088 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1089 assert(hrrs->occupied() == 0, "RSet should be empty");
1090 } else {
1091 hrrs->clear();
1092 }
1093 // You might think here that we could clear just the cards
1094 // corresponding to the used region. But no: if we leave a dirty card
1095 // in a region we might allocate into, then it would prevent that card
1096 // from being enqueued, and cause it to be missed.
1097 // Re: the performance cost: we shouldn't be doing full GC anyway!
1098 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1099
1100 return false;
1101 }
1102 };
1103
1104 void G1CollectedHeap::clear_rsets_post_compaction() {
1105 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1106 heap_region_iterate(&rs_clear);
1107 }
1108
1109 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1110 G1CollectedHeap* _g1h;
1111 UpdateRSOopClosure _cl;
1112 public:
1113 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1114 _cl(g1->g1_rem_set(), worker_i),
1115 _g1h(g1)
1116 { }
1117
1118 bool doHeapRegion(HeapRegion* r) {
1119 if (!r->is_continues_humongous()) {
1120 _cl.set_from(r);
1121 r->oop_iterate(&_cl);
1122 }
1123 return false;
1124 }
1125 };
1126
1127 class ParRebuildRSTask: public AbstractGangTask {
1128 G1CollectedHeap* _g1;
1129 HeapRegionClaimer _hrclaimer;
1130
1131 public:
1132 ParRebuildRSTask(G1CollectedHeap* g1) :
1133 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1134
1135 void work(uint worker_id) {
1136 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1137 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1138 }
1139 };
1140
1141 class PostCompactionPrinterClosure: public HeapRegionClosure {
1142 private:
1143 G1HRPrinter* _hr_printer;
1144 public:
1145 bool doHeapRegion(HeapRegion* hr) {
1146 assert(!hr->is_young(), "not expecting to find young regions");
1147 _hr_printer->post_compaction(hr);
1148 return false;
1149 }
1150
1151 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1152 : _hr_printer(hr_printer) { }
1153 };
1154
1155 void G1CollectedHeap::print_hrm_post_compaction() {
1156 if (_hr_printer.is_active()) {
1157 PostCompactionPrinterClosure cl(hr_printer());
1158 heap_region_iterate(&cl);
1159 }
1160
1161 }
1162
1163 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1164 bool clear_all_soft_refs) {
1165 assert_at_safepoint(true /* should_be_vm_thread */);
1166
1167 if (GCLocker::check_active_before_gc()) {
1168 return false;
1169 }
1170
1171 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1172 gc_timer->register_gc_start();
1173
1174 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1175 GCIdMark gc_id_mark;
1176 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1177
1178 SvcGCMarker sgcm(SvcGCMarker::FULL);
1179 ResourceMark rm;
1180
1181 print_heap_before_gc();
1182 print_heap_regions();
1183 trace_heap_before_gc(gc_tracer);
1184
1185 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1186
1187 _verifier->verify_region_sets_optional();
1188
1189 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1190 collector_policy()->should_clear_all_soft_refs();
1191
1192 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1193
1194 {
1195 IsGCActiveMark x;
1196
1197 // Timing
1198 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1199 GCTraceCPUTime tcpu;
1200
1201 {
1202 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1203 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1204 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1205
1206 G1HeapTransition heap_transition(this);
1207 g1_policy()->record_full_collection_start();
1208
1209 // Note: When we have a more flexible GC logging framework that
1210 // allows us to add optional attributes to a GC log record we
1211 // could consider timing and reporting how long we wait in the
1212 // following two methods.
1213 wait_while_free_regions_coming();
1214 // If we start the compaction before the CM threads finish
1215 // scanning the root regions we might trip them over as we'll
1216 // be moving objects / updating references. So let's wait until
1217 // they are done. By telling them to abort, they should complete
1218 // early.
1219 _cm->root_regions()->abort();
1220 _cm->root_regions()->wait_until_scan_finished();
1221 append_secondary_free_list_if_not_empty_with_lock();
1222
1223 gc_prologue(true);
1224 increment_total_collections(true /* full gc */);
1225 increment_old_marking_cycles_started();
1226
1227 assert(used() == recalculate_used(), "Should be equal");
1228
1229 _verifier->verify_before_gc();
1230
1231 _verifier->check_bitmaps("Full GC Start");
1232 pre_full_gc_dump(gc_timer);
1233
1234 #if defined(COMPILER2) || INCLUDE_JVMCI
1235 DerivedPointerTable::clear();
1236 #endif
1237
1238 // Disable discovery and empty the discovered lists
1239 // for the CM ref processor.
1240 ref_processor_cm()->disable_discovery();
1241 ref_processor_cm()->abandon_partial_discovery();
1242 ref_processor_cm()->verify_no_references_recorded();
1243
1244 // Abandon current iterations of concurrent marking and concurrent
1245 // refinement, if any are in progress.
1246 concurrent_mark()->abort();
1247
1248 // Make sure we'll choose a new allocation region afterwards.
1249 _allocator->release_mutator_alloc_region();
1250 _allocator->abandon_gc_alloc_regions();
1251 g1_rem_set()->cleanupHRRS();
1252
1253 // We may have added regions to the current incremental collection
1254 // set between the last GC or pause and now. We need to clear the
1255 // incremental collection set and then start rebuilding it afresh
1256 // after this full GC.
1257 abandon_collection_set(collection_set());
1258
1259 tear_down_region_sets(false /* free_list_only */);
1260 collector_state()->set_gcs_are_young(true);
1261
1262 // See the comments in g1CollectedHeap.hpp and
1263 // G1CollectedHeap::ref_processing_init() about
1264 // how reference processing currently works in G1.
1265
1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268
1269 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271
1272 ref_processor_stw()->enable_discovery();
1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274
1275 // Do collection work
1276 {
1277 HandleMark hm; // Discard invalid handles created during gc
1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279 }
1280
1281 assert(num_free_regions() == 0, "we should not have added any free regions");
1282 rebuild_region_sets(false /* free_list_only */);
1283
1284 // Enqueue any discovered reference objects that have
1285 // not been removed from the discovered lists.
1286 ref_processor_stw()->enqueue_discovered_references();
1287
1288 #if defined(COMPILER2) || INCLUDE_JVMCI
1289 DerivedPointerTable::update_pointers();
1290 #endif
1291
1292 MemoryService::track_memory_usage();
1293
1294 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1295 ref_processor_stw()->verify_no_references_recorded();
1296
1297 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1298 ClassLoaderDataGraph::purge();
1299 MetaspaceAux::verify_metrics();
1300
1301 // Note: since we've just done a full GC, concurrent
1302 // marking is no longer active. Therefore we need not
1303 // re-enable reference discovery for the CM ref processor.
1304 // That will be done at the start of the next marking cycle.
1305 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1306 ref_processor_cm()->verify_no_references_recorded();
1307
1308 reset_gc_time_stamp();
1309 // Since everything potentially moved, we will clear all remembered
1310 // sets, and clear all cards. Later we will rebuild remembered
1311 // sets. We will also reset the GC time stamps of the regions.
1312 clear_rsets_post_compaction();
1313 check_gc_time_stamps();
1314
1315 resize_if_necessary_after_full_collection();
1316
1317 // We should do this after we potentially resize the heap so
1318 // that all the COMMIT / UNCOMMIT events are generated before
1319 // the compaction events.
1320 print_hrm_post_compaction();
1321
1322 if (_hot_card_cache->use_cache()) {
1323 _hot_card_cache->reset_card_counts();
1324 _hot_card_cache->reset_hot_cache();
1325 }
1326
1327 // Rebuild remembered sets of all regions.
1328 uint n_workers =
1329 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1330 workers()->active_workers(),
1331 Threads::number_of_non_daemon_threads());
1332 workers()->update_active_workers(n_workers);
1333 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1334
1335 ParRebuildRSTask rebuild_rs_task(this);
1336 workers()->run_task(&rebuild_rs_task);
1337
1338 // Rebuild the strong code root lists for each region
1339 rebuild_strong_code_roots();
1340
1341 if (true) { // FIXME
1342 MetaspaceGC::compute_new_size();
1343 }
1344
1345 #ifdef TRACESPINNING
1346 ParallelTaskTerminator::print_termination_counts();
1347 #endif
1348
1349 // Discard all rset updates
1350 JavaThread::dirty_card_queue_set().abandon_logs();
1351 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1352
1353 // At this point there should be no regions in the
1354 // entire heap tagged as young.
1355 assert(check_young_list_empty(), "young list should be empty at this point");
1356
1357 // Update the number of full collections that have been completed.
1358 increment_old_marking_cycles_completed(false /* concurrent */);
1359
1360 _hrm.verify_optional();
1361 _verifier->verify_region_sets_optional();
1362
1363 _verifier->verify_after_gc();
1364
1365 // Clear the previous marking bitmap, if needed for bitmap verification.
1366 // Note we cannot do this when we clear the next marking bitmap in
1367 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1368 // objects marked during a full GC against the previous bitmap.
1369 // But we need to clear it before calling check_bitmaps below since
1370 // the full GC has compacted objects and updated TAMS but not updated
1371 // the prev bitmap.
1372 if (G1VerifyBitmaps) {
1373 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1374 _cm->clear_prev_bitmap(workers());
1375 }
1376 _verifier->check_bitmaps("Full GC End");
1377
1378 start_new_collection_set();
1379
1380 _allocator->init_mutator_alloc_region();
1381
1382 g1_policy()->record_full_collection_end();
1383
1384 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1385 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1386 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1387 // before any GC notifications are raised.
1388 g1mm()->update_sizes();
1389
1390 gc_epilogue(true);
1391
1392 heap_transition.print();
1393
1394 print_heap_after_gc();
1395 print_heap_regions();
1396 trace_heap_after_gc(gc_tracer);
1397
1398 post_full_gc_dump(gc_timer);
1399 }
1400
1401 gc_timer->register_gc_end();
1402 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1403 }
1404
1405 return true;
1406 }
1407
1408 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1409 // Currently, there is no facility in the do_full_collection(bool) API to notify
1410 // the caller that the collection did not succeed (e.g., because it was locked
1411 // out by the GC locker). So, right now, we'll ignore the return value.
1412 bool dummy = do_full_collection(true, /* explicit_gc */
1413 clear_all_soft_refs);
1414 }
1415
1416 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1417 // Include bytes that will be pre-allocated to support collections, as "used".
1418 const size_t used_after_gc = used();
1419 const size_t capacity_after_gc = capacity();
1420 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1421
1422 // This is enforced in arguments.cpp.
1423 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1424 "otherwise the code below doesn't make sense");
1425
1426 // We don't have floating point command-line arguments
1427 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1428 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1429 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1430 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1431
1432 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1433 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1434
1435 // We have to be careful here as these two calculations can overflow
1436 // 32-bit size_t's.
1437 double used_after_gc_d = (double) used_after_gc;
1438 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1439 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1440
1441 // Let's make sure that they are both under the max heap size, which
1442 // by default will make them fit into a size_t.
1443 double desired_capacity_upper_bound = (double) max_heap_size;
1444 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1445 desired_capacity_upper_bound);
1446 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1447 desired_capacity_upper_bound);
1448
1449 // We can now safely turn them into size_t's.
1450 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1451 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1452
1453 // This assert only makes sense here, before we adjust them
1454 // with respect to the min and max heap size.
1455 assert(minimum_desired_capacity <= maximum_desired_capacity,
1456 "minimum_desired_capacity = " SIZE_FORMAT ", "
1457 "maximum_desired_capacity = " SIZE_FORMAT,
1458 minimum_desired_capacity, maximum_desired_capacity);
1459
1460 // Should not be greater than the heap max size. No need to adjust
1461 // it with respect to the heap min size as it's a lower bound (i.e.,
1462 // we'll try to make the capacity larger than it, not smaller).
1463 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1464 // Should not be less than the heap min size. No need to adjust it
1465 // with respect to the heap max size as it's an upper bound (i.e.,
1466 // we'll try to make the capacity smaller than it, not greater).
1467 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1468
1469 if (capacity_after_gc < minimum_desired_capacity) {
1470 // Don't expand unless it's significant
1471 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1472
1473 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1474 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1475 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1476
1477 expand(expand_bytes, _workers);
1478
1479 // No expansion, now see if we want to shrink
1480 } else if (capacity_after_gc > maximum_desired_capacity) {
1481 // Capacity too large, compute shrinking size
1482 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1483
1484 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1485 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1486 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1487
1488 shrink(shrink_bytes);
1489 }
1490 }
1491
1492 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1493 AllocationContext_t context,
1494 bool do_gc,
1495 bool clear_all_soft_refs,
1496 bool expect_null_mutator_alloc_region,
1497 bool* gc_succeeded) {
1498 *gc_succeeded = true;
1499 // Let's attempt the allocation first.
1500 HeapWord* result =
1501 attempt_allocation_at_safepoint(word_size,
1502 context,
1503 expect_null_mutator_alloc_region);
1504 if (result != NULL) {
1505 assert(*gc_succeeded, "sanity");
1506 return result;
1507 }
1508
1509 // In a G1 heap, we're supposed to keep allocation from failing by
1510 // incremental pauses. Therefore, at least for now, we'll favor
1511 // expansion over collection. (This might change in the future if we can
1512 // do something smarter than full collection to satisfy a failed alloc.)
1513 result = expand_and_allocate(word_size, context);
1514 if (result != NULL) {
1515 assert(*gc_succeeded, "sanity");
1516 return result;
1517 }
1518
1519 if (do_gc) {
1520 // Expansion didn't work, we'll try to do a Full GC.
1521 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1522 clear_all_soft_refs);
1523 }
1524
1525 return NULL;
1526 }
1527
1528 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1529 AllocationContext_t context,
1530 bool* succeeded) {
1531 assert_at_safepoint(true /* should_be_vm_thread */);
1532
1533 // Attempts to allocate followed by Full GC.
1534 HeapWord* result =
1535 satisfy_failed_allocation_helper(word_size,
1536 context,
1537 true, /* do_gc */
1538 false, /* clear_all_soft_refs */
1539 false, /* expect_null_mutator_alloc_region */
1540 succeeded);
1541
1542 if (result != NULL || !*succeeded) {
1543 return result;
1544 }
1545
1546 // Attempts to allocate followed by Full GC that will collect all soft references.
1547 result = satisfy_failed_allocation_helper(word_size,
1548 context,
1549 true, /* do_gc */
1550 true, /* clear_all_soft_refs */
1551 true, /* expect_null_mutator_alloc_region */
1552 succeeded);
1553
1554 if (result != NULL || !*succeeded) {
1555 return result;
1556 }
1557
1558 // Attempts to allocate, no GC
1559 result = satisfy_failed_allocation_helper(word_size,
1560 context,
1561 false, /* do_gc */
1562 false, /* clear_all_soft_refs */
1563 true, /* expect_null_mutator_alloc_region */
1564 succeeded);
1565
1566 if (result != NULL) {
1567 assert(*succeeded, "sanity");
1568 return result;
1569 }
1570
1571 assert(!collector_policy()->should_clear_all_soft_refs(),
1572 "Flag should have been handled and cleared prior to this point");
1573
1574 // What else? We might try synchronous finalization later. If the total
1575 // space available is large enough for the allocation, then a more
1576 // complete compaction phase than we've tried so far might be
1577 // appropriate.
1578 assert(*succeeded, "sanity");
1579 return NULL;
1580 }
1581
1582 // Attempting to expand the heap sufficiently
1583 // to support an allocation of the given "word_size". If
1584 // successful, perform the allocation and return the address of the
1585 // allocated block, or else "NULL".
1586
1587 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1588 assert_at_safepoint(true /* should_be_vm_thread */);
1589
1590 _verifier->verify_region_sets_optional();
1591
1592 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1593 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1594 word_size * HeapWordSize);
1595
1596
1597 if (expand(expand_bytes, _workers)) {
1598 _hrm.verify_optional();
1599 _verifier->verify_region_sets_optional();
1600 return attempt_allocation_at_safepoint(word_size,
1601 context,
1602 false /* expect_null_mutator_alloc_region */);
1603 }
1604 return NULL;
1605 }
1606
1607 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1608 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1609 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1610 HeapRegion::GrainBytes);
1611
1612 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1613 expand_bytes, aligned_expand_bytes);
1614
1615 if (is_maximal_no_gc()) {
1616 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1617 return false;
1618 }
1619
1620 double expand_heap_start_time_sec = os::elapsedTime();
1621 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1622 assert(regions_to_expand > 0, "Must expand by at least one region");
1623
1624 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1625 if (expand_time_ms != NULL) {
1626 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1627 }
1628
1629 if (expanded_by > 0) {
1630 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1631 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1632 g1_policy()->record_new_heap_size(num_regions());
1633 } else {
1634 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1635
1636 // The expansion of the virtual storage space was unsuccessful.
1637 // Let's see if it was because we ran out of swap.
1638 if (G1ExitOnExpansionFailure &&
1639 _hrm.available() >= regions_to_expand) {
1640 // We had head room...
1641 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1642 }
1643 }
1644 return regions_to_expand > 0;
1645 }
1646
1647 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1648 size_t aligned_shrink_bytes =
1649 ReservedSpace::page_align_size_down(shrink_bytes);
1650 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1651 HeapRegion::GrainBytes);
1652 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1653
1654 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1655 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1656
1657
1658 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",
1659 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1660 if (num_regions_removed > 0) {
1661 g1_policy()->record_new_heap_size(num_regions());
1662 } else {
1663 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1664 }
1665 }
1666
1667 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1668 _verifier->verify_region_sets_optional();
1669
1670 // We should only reach here at the end of a Full GC which means we
1671 // should not not be holding to any GC alloc regions. The method
1672 // below will make sure of that and do any remaining clean up.
1673 _allocator->abandon_gc_alloc_regions();
1674
1675 // Instead of tearing down / rebuilding the free lists here, we
1676 // could instead use the remove_all_pending() method on free_list to
1677 // remove only the ones that we need to remove.
1678 tear_down_region_sets(true /* free_list_only */);
1679 shrink_helper(shrink_bytes);
1680 rebuild_region_sets(true /* free_list_only */);
1681
1682 _hrm.verify_optional();
1683 _verifier->verify_region_sets_optional();
1684 }
1685
1686 // Public methods.
1687
1688 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1689 CollectedHeap(),
1690 _collector_policy(collector_policy),
1691 _g1_policy(create_g1_policy()),
1692 _collection_set(this, _g1_policy),
1693 _dirty_card_queue_set(false),
1694 _is_alive_closure_cm(this),
1695 _is_alive_closure_stw(this),
1696 _ref_processor_cm(NULL),
1697 _ref_processor_stw(NULL),
1698 _bot(NULL),
1699 _hot_card_cache(NULL),
1700 _g1_rem_set(NULL),
1701 _cg1r(NULL),
1702 _g1mm(NULL),
1703 _refine_cte_cl(NULL),
1704 _preserved_marks_set(true /* in_c_heap */),
1705 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1706 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1707 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1708 _humongous_reclaim_candidates(),
1709 _has_humongous_reclaim_candidates(false),
1710 _archive_allocator(NULL),
1711 _free_regions_coming(false),
1712 _gc_time_stamp(0),
1713 _summary_bytes_used(0),
1714 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1715 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1716 _expand_heap_after_alloc_failure(true),
1717 _old_marking_cycles_started(0),
1718 _old_marking_cycles_completed(0),
1719 _in_cset_fast_test(),
1720 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1721 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()) {
1722
1723 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1724 /* are_GC_task_threads */true,
1725 /* are_ConcurrentGC_threads */false);
1726 _workers->initialize_workers();
1727 _verifier = new G1HeapVerifier(this);
1728
1729 _allocator = G1Allocator::create_allocator(this);
1730
1731 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1732
1733 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1734
1735 // Override the default _filler_array_max_size so that no humongous filler
1736 // objects are created.
1737 _filler_array_max_size = _humongous_object_threshold_in_words;
1738
1739 uint n_queues = ParallelGCThreads;
1740 _task_queues = new RefToScanQueueSet(n_queues);
1741
1742 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1743
1744 for (uint i = 0; i < n_queues; i++) {
1745 RefToScanQueue* q = new RefToScanQueue();
1746 q->initialize();
1747 _task_queues->register_queue(i, q);
1748 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1749 }
1750
1751 // Initialize the G1EvacuationFailureALot counters and flags.
1752 NOT_PRODUCT(reset_evacuation_should_fail();)
1753
1754 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1755 }
1756
1757 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1758 size_t size,
1759 size_t translation_factor) {
1760 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1761 // Allocate a new reserved space, preferring to use large pages.
1762 ReservedSpace rs(size, preferred_page_size);
1763 G1RegionToSpaceMapper* result =
1764 G1RegionToSpaceMapper::create_mapper(rs,
1765 size,
1766 rs.alignment(),
1767 HeapRegion::GrainBytes,
1768 translation_factor,
1769 mtGC);
1770
1771 os::trace_page_sizes_for_requested_size(description,
1772 size,
1773 preferred_page_size,
1774 rs.alignment(),
1775 rs.base(),
1776 rs.size());
1777
1778 return result;
1779 }
1780
1781 jint G1CollectedHeap::initialize() {
1782 CollectedHeap::pre_initialize();
1783 os::enable_vtime();
1784
1785 // Necessary to satisfy locking discipline assertions.
1786
1787 MutexLocker x(Heap_lock);
1788
1789 // While there are no constraints in the GC code that HeapWordSize
1790 // be any particular value, there are multiple other areas in the
1791 // system which believe this to be true (e.g. oop->object_size in some
1792 // cases incorrectly returns the size in wordSize units rather than
1793 // HeapWordSize).
1794 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1795
1796 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1797 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1798 size_t heap_alignment = collector_policy()->heap_alignment();
1799
1800 // Ensure that the sizes are properly aligned.
1801 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1802 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1803 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1804
1805 _refine_cte_cl = new RefineCardTableEntryClosure();
1806
1807 jint ecode = JNI_OK;
1808 _cg1r = ConcurrentG1Refine::create(_refine_cte_cl, &ecode);
1809 if (_cg1r == NULL) {
1810 return ecode;
1811 }
1812
1813 // Reserve the maximum.
1814
1815 // When compressed oops are enabled, the preferred heap base
1816 // is calculated by subtracting the requested size from the
1817 // 32Gb boundary and using the result as the base address for
1818 // heap reservation. If the requested size is not aligned to
1819 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1820 // into the ReservedHeapSpace constructor) then the actual
1821 // base of the reserved heap may end up differing from the
1822 // address that was requested (i.e. the preferred heap base).
1823 // If this happens then we could end up using a non-optimal
1824 // compressed oops mode.
1825
1826 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1827 heap_alignment);
1828
1829 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1830
1831 // Create the barrier set for the entire reserved region.
1832 G1SATBCardTableLoggingModRefBS* bs
1833 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1834 bs->initialize();
1835 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1836 set_barrier_set(bs);
1837
1838 // Create the hot card cache.
1839 _hot_card_cache = new G1HotCardCache(this);
1840
1841 // Also create a G1 rem set.
1842 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1843
1844 // Carve out the G1 part of the heap.
1845 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1846 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1847 G1RegionToSpaceMapper* heap_storage =
1848 G1RegionToSpaceMapper::create_mapper(g1_rs,
1849 g1_rs.size(),
1850 page_size,
1851 HeapRegion::GrainBytes,
1852 1,
1853 mtJavaHeap);
1854 os::trace_page_sizes("Heap",
1855 collector_policy()->min_heap_byte_size(),
1856 max_byte_size,
1857 page_size,
1858 heap_rs.base(),
1859 heap_rs.size());
1860 heap_storage->set_mapping_changed_listener(&_listener);
1861
1862 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1863 G1RegionToSpaceMapper* bot_storage =
1864 create_aux_memory_mapper("Block Offset Table",
1865 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1866 G1BlockOffsetTable::heap_map_factor());
1867
1868 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1869 G1RegionToSpaceMapper* cardtable_storage =
1870 create_aux_memory_mapper("Card Table",
1871 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1872 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1873
1874 G1RegionToSpaceMapper* card_counts_storage =
1875 create_aux_memory_mapper("Card Counts Table",
1876 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1877 G1CardCounts::heap_map_factor());
1878
1879 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1880 G1RegionToSpaceMapper* prev_bitmap_storage =
1881 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1882 G1RegionToSpaceMapper* next_bitmap_storage =
1883 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1884
1885 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1886 g1_barrier_set()->initialize(cardtable_storage);
1887 // Do later initialization work for concurrent refinement.
1888 _hot_card_cache->initialize(card_counts_storage);
1889
1890 // 6843694 - ensure that the maximum region index can fit
1891 // in the remembered set structures.
1892 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1893 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1894
1895 g1_rem_set()->initialize(max_capacity(), max_regions());
1896
1897 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1898 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1899 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1900 "too many cards per region");
1901
1902 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1903
1904 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1905
1906 {
1907 HeapWord* start = _hrm.reserved().start();
1908 HeapWord* end = _hrm.reserved().end();
1909 size_t granularity = HeapRegion::GrainBytes;
1910
1911 _in_cset_fast_test.initialize(start, end, granularity);
1912 _humongous_reclaim_candidates.initialize(start, end, granularity);
1913 }
1914
1915 // Create the G1ConcurrentMark data structure and thread.
1916 // (Must do this late, so that "max_regions" is defined.)
1917 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1918 if (_cm == NULL || !_cm->completed_initialization()) {
1919 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1920 return JNI_ENOMEM;
1921 }
1922 _cmThread = _cm->cmThread();
1923
1924 // Now expand into the initial heap size.
1925 if (!expand(init_byte_size, _workers)) {
1926 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1927 return JNI_ENOMEM;
1928 }
1929
1930 // Perform any initialization actions delegated to the policy.
1931 g1_policy()->init(this, &_collection_set);
1932
1933 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1934 SATB_Q_FL_lock,
1935 G1SATBProcessCompletedThreshold,
1936 Shared_SATB_Q_lock);
1937
1938 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1939 DirtyCardQ_CBL_mon,
1940 DirtyCardQ_FL_lock,
1941 (int)concurrent_g1_refine()->yellow_zone(),
1942 (int)concurrent_g1_refine()->red_zone(),
1943 Shared_DirtyCardQ_lock,
1944 NULL, // fl_owner
1945 true); // init_free_ids
1946
1947 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1948 DirtyCardQ_CBL_mon,
1949 DirtyCardQ_FL_lock,
1950 -1, // never trigger processing
1951 -1, // no limit on length
1952 Shared_DirtyCardQ_lock,
1953 &JavaThread::dirty_card_queue_set());
1954
1955 // Here we allocate the dummy HeapRegion that is required by the
1956 // G1AllocRegion class.
1957 HeapRegion* dummy_region = _hrm.get_dummy_region();
1958
1959 // We'll re-use the same region whether the alloc region will
1960 // require BOT updates or not and, if it doesn't, then a non-young
1961 // region will complain that it cannot support allocations without
1962 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1963 dummy_region->set_eden();
1964 // Make sure it's full.
1965 dummy_region->set_top(dummy_region->end());
1966 G1AllocRegion::setup(this, dummy_region);
1967
1968 _allocator->init_mutator_alloc_region();
1969
1970 // Do create of the monitoring and management support so that
1971 // values in the heap have been properly initialized.
1972 _g1mm = new G1MonitoringSupport(this);
1973
1974 G1StringDedup::initialize();
1975
1976 _preserved_marks_set.init(ParallelGCThreads);
1977
1978 _collection_set.initialize(max_regions());
1979
1980 return JNI_OK;
1981 }
1982
1983 void G1CollectedHeap::stop() {
1984 // Stop all concurrent threads. We do this to make sure these threads
1985 // do not continue to execute and access resources (e.g. logging)
1986 // that are destroyed during shutdown.
1987 _cg1r->stop();
1988 _cmThread->stop();
1989 if (G1StringDedup::is_enabled()) {
1990 G1StringDedup::stop();
1991 }
1992 }
1993
1994 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1995 return HeapRegion::max_region_size();
1996 }
1997
1998 void G1CollectedHeap::post_initialize() {
1999 ref_processing_init();
2000 }
2001
2002 void G1CollectedHeap::ref_processing_init() {
2003 // Reference processing in G1 currently works as follows:
2004 //
2005 // * There are two reference processor instances. One is
2006 // used to record and process discovered references
2007 // during concurrent marking; the other is used to
2008 // record and process references during STW pauses
2009 // (both full and incremental).
2010 // * Both ref processors need to 'span' the entire heap as
2011 // the regions in the collection set may be dotted around.
2012 //
2013 // * For the concurrent marking ref processor:
2014 // * Reference discovery is enabled at initial marking.
2015 // * Reference discovery is disabled and the discovered
2016 // references processed etc during remarking.
2017 // * Reference discovery is MT (see below).
2018 // * Reference discovery requires a barrier (see below).
2019 // * Reference processing may or may not be MT
2020 // (depending on the value of ParallelRefProcEnabled
2021 // and ParallelGCThreads).
2022 // * A full GC disables reference discovery by the CM
2023 // ref processor and abandons any entries on it's
2024 // discovered lists.
2025 //
2026 // * For the STW processor:
2027 // * Non MT discovery is enabled at the start of a full GC.
2028 // * Processing and enqueueing during a full GC is non-MT.
2029 // * During a full GC, references are processed after marking.
2030 //
2031 // * Discovery (may or may not be MT) is enabled at the start
2032 // of an incremental evacuation pause.
2033 // * References are processed near the end of a STW evacuation pause.
2034 // * For both types of GC:
2035 // * Discovery is atomic - i.e. not concurrent.
2036 // * Reference discovery will not need a barrier.
2037
2038 MemRegion mr = reserved_region();
2039
2040 // Concurrent Mark ref processor
2041 _ref_processor_cm =
2042 new ReferenceProcessor(mr, // span
2043 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2044 // mt processing
2045 ParallelGCThreads,
2046 // degree of mt processing
2047 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2048 // mt discovery
2049 MAX2(ParallelGCThreads, ConcGCThreads),
2050 // degree of mt discovery
2051 false,
2052 // Reference discovery is not atomic
2053 &_is_alive_closure_cm);
2054 // is alive closure
2055 // (for efficiency/performance)
2056
2057 // STW ref processor
2058 _ref_processor_stw =
2059 new ReferenceProcessor(mr, // span
2060 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2061 // mt processing
2062 ParallelGCThreads,
2063 // degree of mt processing
2064 (ParallelGCThreads > 1),
2065 // mt discovery
2066 ParallelGCThreads,
2067 // degree of mt discovery
2068 true,
2069 // Reference discovery is atomic
2070 &_is_alive_closure_stw);
2071 // is alive closure
2072 // (for efficiency/performance)
2073 }
2074
2075 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2076 return _collector_policy;
2077 }
2078
2079 size_t G1CollectedHeap::capacity() const {
2080 return _hrm.length() * HeapRegion::GrainBytes;
2081 }
2082
2083 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2084 hr->reset_gc_time_stamp();
2085 }
2086
2087 #ifndef PRODUCT
2088
2089 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2090 private:
2091 unsigned _gc_time_stamp;
2092 bool _failures;
2093
2094 public:
2095 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2096 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2097
2098 virtual bool doHeapRegion(HeapRegion* hr) {
2099 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2100 if (_gc_time_stamp != region_gc_time_stamp) {
2101 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2102 region_gc_time_stamp, _gc_time_stamp);
2103 _failures = true;
2104 }
2105 return false;
2106 }
2107
2108 bool failures() { return _failures; }
2109 };
2110
2111 void G1CollectedHeap::check_gc_time_stamps() {
2112 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2113 heap_region_iterate(&cl);
2114 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2115 }
2116 #endif // PRODUCT
2117
2118 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2119 _hot_card_cache->drain(cl, worker_i);
2120 }
2121
2122 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2123 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2124 size_t n_completed_buffers = 0;
2125 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2126 n_completed_buffers++;
2127 }
2128 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2129 dcqs.clear_n_completed_buffers();
2130 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2131 }
2132
2133 // Computes the sum of the storage used by the various regions.
2134 size_t G1CollectedHeap::used() const {
2135 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2136 if (_archive_allocator != NULL) {
2137 result += _archive_allocator->used();
2138 }
2139 return result;
2140 }
2141
2142 size_t G1CollectedHeap::used_unlocked() const {
2143 return _summary_bytes_used;
2144 }
2145
2146 class SumUsedClosure: public HeapRegionClosure {
2147 size_t _used;
2148 public:
2149 SumUsedClosure() : _used(0) {}
2150 bool doHeapRegion(HeapRegion* r) {
2151 _used += r->used();
2152 return false;
2153 }
2154 size_t result() { return _used; }
2155 };
2156
2157 size_t G1CollectedHeap::recalculate_used() const {
2158 double recalculate_used_start = os::elapsedTime();
2159
2160 SumUsedClosure blk;
2161 heap_region_iterate(&blk);
2162
2163 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2164 return blk.result();
2165 }
2166
2167 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2168 switch (cause) {
2169 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2170 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2171 case GCCause::_update_allocation_context_stats_inc: return true;
2172 case GCCause::_wb_conc_mark: return true;
2173 default : return false;
2174 }
2175 }
2176
2177 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2178 switch (cause) {
2179 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2180 case GCCause::_g1_humongous_allocation: return true;
2181 default: return is_user_requested_concurrent_full_gc(cause);
2182 }
2183 }
2184
2185 #ifndef PRODUCT
2186 void G1CollectedHeap::allocate_dummy_regions() {
2187 // Let's fill up most of the region
2188 size_t word_size = HeapRegion::GrainWords - 1024;
2189 // And as a result the region we'll allocate will be humongous.
2190 guarantee(is_humongous(word_size), "sanity");
2191
2192 // _filler_array_max_size is set to humongous object threshold
2193 // but temporarily change it to use CollectedHeap::fill_with_object().
2194 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2195
2196 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2197 // Let's use the existing mechanism for the allocation
2198 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2199 AllocationContext::system());
2200 if (dummy_obj != NULL) {
2201 MemRegion mr(dummy_obj, word_size);
2202 CollectedHeap::fill_with_object(mr);
2203 } else {
2204 // If we can't allocate once, we probably cannot allocate
2205 // again. Let's get out of the loop.
2206 break;
2207 }
2208 }
2209 }
2210 #endif // !PRODUCT
2211
2212 void G1CollectedHeap::increment_old_marking_cycles_started() {
2213 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2214 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2215 "Wrong marking cycle count (started: %d, completed: %d)",
2216 _old_marking_cycles_started, _old_marking_cycles_completed);
2217
2218 _old_marking_cycles_started++;
2219 }
2220
2221 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2222 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2223
2224 // We assume that if concurrent == true, then the caller is a
2225 // concurrent thread that was joined the Suspendible Thread
2226 // Set. If there's ever a cheap way to check this, we should add an
2227 // assert here.
2228
2229 // Given that this method is called at the end of a Full GC or of a
2230 // concurrent cycle, and those can be nested (i.e., a Full GC can
2231 // interrupt a concurrent cycle), the number of full collections
2232 // completed should be either one (in the case where there was no
2233 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2234 // behind the number of full collections started.
2235
2236 // This is the case for the inner caller, i.e. a Full GC.
2237 assert(concurrent ||
2238 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2239 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2240 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2241 "is inconsistent with _old_marking_cycles_completed = %u",
2242 _old_marking_cycles_started, _old_marking_cycles_completed);
2243
2244 // This is the case for the outer caller, i.e. the concurrent cycle.
2245 assert(!concurrent ||
2246 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2247 "for outer caller (concurrent cycle): "
2248 "_old_marking_cycles_started = %u "
2249 "is inconsistent with _old_marking_cycles_completed = %u",
2250 _old_marking_cycles_started, _old_marking_cycles_completed);
2251
2252 _old_marking_cycles_completed += 1;
2253
2254 // We need to clear the "in_progress" flag in the CM thread before
2255 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2256 // is set) so that if a waiter requests another System.gc() it doesn't
2257 // incorrectly see that a marking cycle is still in progress.
2258 if (concurrent) {
2259 _cmThread->set_idle();
2260 }
2261
2262 // This notify_all() will ensure that a thread that called
2263 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2264 // and it's waiting for a full GC to finish will be woken up. It is
2265 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2266 FullGCCount_lock->notify_all();
2267 }
2268
2269 void G1CollectedHeap::collect(GCCause::Cause cause) {
2270 assert_heap_not_locked();
2271
2272 uint gc_count_before;
2273 uint old_marking_count_before;
2274 uint full_gc_count_before;
2275 bool retry_gc;
2276
2277 do {
2278 retry_gc = false;
2279
2280 {
2281 MutexLocker ml(Heap_lock);
2282
2283 // Read the GC count while holding the Heap_lock
2284 gc_count_before = total_collections();
2285 full_gc_count_before = total_full_collections();
2286 old_marking_count_before = _old_marking_cycles_started;
2287 }
2288
2289 if (should_do_concurrent_full_gc(cause)) {
2290 // Schedule an initial-mark evacuation pause that will start a
2291 // concurrent cycle. We're setting word_size to 0 which means that
2292 // we are not requesting a post-GC allocation.
2293 VM_G1IncCollectionPause op(gc_count_before,
2294 0, /* word_size */
2295 true, /* should_initiate_conc_mark */
2296 g1_policy()->max_pause_time_ms(),
2297 cause);
2298 op.set_allocation_context(AllocationContext::current());
2299
2300 VMThread::execute(&op);
2301 if (!op.pause_succeeded()) {
2302 if (old_marking_count_before == _old_marking_cycles_started) {
2303 retry_gc = op.should_retry_gc();
2304 } else {
2305 // A Full GC happened while we were trying to schedule the
2306 // initial-mark GC. No point in starting a new cycle given
2307 // that the whole heap was collected anyway.
2308 }
2309
2310 if (retry_gc) {
2311 if (GCLocker::is_active_and_needs_gc()) {
2312 GCLocker::stall_until_clear();
2313 }
2314 }
2315 }
2316 } else {
2317 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2318 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2319
2320 // Schedule a standard evacuation pause. We're setting word_size
2321 // to 0 which means that we are not requesting a post-GC allocation.
2322 VM_G1IncCollectionPause op(gc_count_before,
2323 0, /* word_size */
2324 false, /* should_initiate_conc_mark */
2325 g1_policy()->max_pause_time_ms(),
2326 cause);
2327 VMThread::execute(&op);
2328 } else {
2329 // Schedule a Full GC.
2330 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2331 VMThread::execute(&op);
2332 }
2333 }
2334 } while (retry_gc);
2335 }
2336
2337 bool G1CollectedHeap::is_in(const void* p) const {
2338 if (_hrm.reserved().contains(p)) {
2339 // Given that we know that p is in the reserved space,
2340 // heap_region_containing() should successfully
2341 // return the containing region.
2342 HeapRegion* hr = heap_region_containing(p);
2343 return hr->is_in(p);
2344 } else {
2345 return false;
2346 }
2347 }
2348
2349 #ifdef ASSERT
2350 bool G1CollectedHeap::is_in_exact(const void* p) const {
2351 bool contains = reserved_region().contains(p);
2352 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2353 if (contains && available) {
2354 return true;
2355 } else {
2356 return false;
2357 }
2358 }
2359 #endif
2360
2361 // Iteration functions.
2362
2363 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2364
2365 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2366 ExtendedOopClosure* _cl;
2367 public:
2368 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2369 bool doHeapRegion(HeapRegion* r) {
2370 if (!r->is_continues_humongous()) {
2371 r->oop_iterate(_cl);
2372 }
2373 return false;
2374 }
2375 };
2376
2377 // Iterates an ObjectClosure over all objects within a HeapRegion.
2378
2379 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2380 ObjectClosure* _cl;
2381 public:
2382 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2383 bool doHeapRegion(HeapRegion* r) {
2384 if (!r->is_continues_humongous()) {
2385 r->object_iterate(_cl);
2386 }
2387 return false;
2388 }
2389 };
2390
2391 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2392 IterateObjectClosureRegionClosure blk(cl);
2393 heap_region_iterate(&blk);
2394 }
2395
2396 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2397 _hrm.iterate(cl);
2398 }
2399
2400 void
2401 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2402 uint worker_id,
2403 HeapRegionClaimer *hrclaimer,
2404 bool concurrent) const {
2405 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2406 }
2407
2408 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2409 _collection_set.iterate(cl);
2410 }
2411
2412 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2413 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2414 }
2415
2416 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2417 HeapRegion* result = _hrm.next_region_in_heap(from);
2418 while (result != NULL && result->is_pinned()) {
2419 result = _hrm.next_region_in_heap(result);
2420 }
2421 return result;
2422 }
2423
2424 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2425 HeapRegion* hr = heap_region_containing(addr);
2426 return hr->block_start(addr);
2427 }
2428
2429 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2430 HeapRegion* hr = heap_region_containing(addr);
2431 return hr->block_size(addr);
2432 }
2433
2434 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2435 HeapRegion* hr = heap_region_containing(addr);
2436 return hr->block_is_obj(addr);
2437 }
2438
2439 bool G1CollectedHeap::supports_tlab_allocation() const {
2440 return true;
2441 }
2442
2443 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2444 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2445 }
2446
2447 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2448 return _eden.length() * HeapRegion::GrainBytes;
2449 }
2450
2451 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2452 // must be equal to the humongous object limit.
2453 size_t G1CollectedHeap::max_tlab_size() const {
2454 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2455 }
2456
2457 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2458 AllocationContext_t context = AllocationContext::current();
2459 return _allocator->unsafe_max_tlab_alloc(context);
2460 }
2461
2462 size_t G1CollectedHeap::max_capacity() const {
2463 return _hrm.reserved().byte_size();
2464 }
2465
2466 jlong G1CollectedHeap::millis_since_last_gc() {
2467 // See the notes in GenCollectedHeap::millis_since_last_gc()
2468 // for more information about the implementation.
2469 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2470 _g1_policy->collection_pause_end_millis();
2471 if (ret_val < 0) {
2472 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2473 ". returning zero instead.", ret_val);
2474 return 0;
2475 }
2476 return ret_val;
2477 }
2478
2479 void G1CollectedHeap::prepare_for_verify() {
2480 _verifier->prepare_for_verify();
2481 }
2482
2483 void G1CollectedHeap::verify(VerifyOption vo) {
2484 _verifier->verify(vo);
2485 }
2486
2487 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2488 return true;
2489 }
2490
2491 const char* const* G1CollectedHeap::concurrent_phases() const {
2492 return _cmThread->concurrent_phases();
2493 }
2494
2495 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2496 return _cmThread->request_concurrent_phase(phase);
2497 }
2498
2499 class PrintRegionClosure: public HeapRegionClosure {
2500 outputStream* _st;
2501 public:
2502 PrintRegionClosure(outputStream* st) : _st(st) {}
2503 bool doHeapRegion(HeapRegion* r) {
2504 r->print_on(_st);
2505 return false;
2506 }
2507 };
2508
2509 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2510 const HeapRegion* hr,
2511 const VerifyOption vo) const {
2512 switch (vo) {
2513 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2514 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2515 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2516 default: ShouldNotReachHere();
2517 }
2518 return false; // keep some compilers happy
2519 }
2520
2521 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2522 const VerifyOption vo) const {
2523 switch (vo) {
2524 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2525 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2526 case VerifyOption_G1UseMarkWord: {
2527 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2528 return !obj->is_gc_marked() && !hr->is_archive();
2529 }
2530 default: ShouldNotReachHere();
2531 }
2532 return false; // keep some compilers happy
2533 }
2534
2535 void G1CollectedHeap::print_heap_regions() const {
2536 Log(gc, heap, region) log;
2537 if (log.is_trace()) {
2538 ResourceMark rm;
2539 print_regions_on(log.trace_stream());
2540 }
2541 }
2542
2543 void G1CollectedHeap::print_on(outputStream* st) const {
2544 st->print(" %-20s", "garbage-first heap");
2545 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2546 capacity()/K, used_unlocked()/K);
2547 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2548 p2i(_hrm.reserved().start()),
2549 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2550 p2i(_hrm.reserved().end()));
2551 st->cr();
2552 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2553 uint young_regions = young_regions_count();
2554 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2555 (size_t) young_regions * HeapRegion::GrainBytes / K);
2556 uint survivor_regions = survivor_regions_count();
2557 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2558 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2559 st->cr();
2560 MetaspaceAux::print_on(st);
2561 }
2562
2563 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2564 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2565 "HS=humongous(starts), HC=humongous(continues), "
2566 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2567 "AC=allocation context, "
2568 "TAMS=top-at-mark-start (previous, next)");
2569 PrintRegionClosure blk(st);
2570 heap_region_iterate(&blk);
2571 }
2572
2573 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2574 print_on(st);
2575
2576 // Print the per-region information.
2577 print_regions_on(st);
2578 }
2579
2580 void G1CollectedHeap::print_on_error(outputStream* st) const {
2581 this->CollectedHeap::print_on_error(st);
2582
2583 if (_cm != NULL) {
2584 st->cr();
2585 _cm->print_on_error(st);
2586 }
2587 }
2588
2589 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2590 workers()->print_worker_threads_on(st);
2591 _cmThread->print_on(st);
2592 st->cr();
2593 _cm->print_worker_threads_on(st);
2594 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2595 if (G1StringDedup::is_enabled()) {
2596 G1StringDedup::print_worker_threads_on(st);
2597 }
2598 }
2599
2600 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2601 workers()->threads_do(tc);
2602 tc->do_thread(_cmThread);
2603 _cm->threads_do(tc);
2604 _cg1r->threads_do(tc); // also iterates over the sample thread
2605 if (G1StringDedup::is_enabled()) {
2606 G1StringDedup::threads_do(tc);
2607 }
2608 }
2609
2610 void G1CollectedHeap::print_tracing_info() const {
2611 g1_rem_set()->print_summary_info();
2612 concurrent_mark()->print_summary_info();
2613 }
2614
2615 #ifndef PRODUCT
2616 // Helpful for debugging RSet issues.
2617
2618 class PrintRSetsClosure : public HeapRegionClosure {
2619 private:
2620 const char* _msg;
2621 size_t _occupied_sum;
2622
2623 public:
2624 bool doHeapRegion(HeapRegion* r) {
2625 HeapRegionRemSet* hrrs = r->rem_set();
2626 size_t occupied = hrrs->occupied();
2627 _occupied_sum += occupied;
2628
2629 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2630 if (occupied == 0) {
2631 tty->print_cr(" RSet is empty");
2632 } else {
2633 hrrs->print();
2634 }
2635 tty->print_cr("----------");
2636 return false;
2637 }
2638
2639 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2640 tty->cr();
2641 tty->print_cr("========================================");
2642 tty->print_cr("%s", msg);
2643 tty->cr();
2644 }
2645
2646 ~PrintRSetsClosure() {
2647 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2648 tty->print_cr("========================================");
2649 tty->cr();
2650 }
2651 };
2652
2653 void G1CollectedHeap::print_cset_rsets() {
2654 PrintRSetsClosure cl("Printing CSet RSets");
2655 collection_set_iterate(&cl);
2656 }
2657
2658 void G1CollectedHeap::print_all_rsets() {
2659 PrintRSetsClosure cl("Printing All RSets");;
2660 heap_region_iterate(&cl);
2661 }
2662 #endif // PRODUCT
2663
2664 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2665
2666 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2667 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2668 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2669
2670 size_t eden_capacity_bytes =
2671 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2672
2673 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2674 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2675 eden_capacity_bytes, survivor_used_bytes, num_regions());
2676 }
2677
2678 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2679 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2680 stats->unused(), stats->used(), stats->region_end_waste(),
2681 stats->regions_filled(), stats->direct_allocated(),
2682 stats->failure_used(), stats->failure_waste());
2683 }
2684
2685 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2686 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2687 gc_tracer->report_gc_heap_summary(when, heap_summary);
2688
2689 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2690 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2691 }
2692
2693 G1CollectedHeap* G1CollectedHeap::heap() {
2694 CollectedHeap* heap = Universe::heap();
2695 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2696 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2697 return (G1CollectedHeap*)heap;
2698 }
2699
2700 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2701 // always_do_update_barrier = false;
2702 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2703
2704 double start = os::elapsedTime();
2705 // Fill TLAB's and such
2706 accumulate_statistics_all_tlabs();
2707 ensure_parsability(true);
2708 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2709
2710 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2711 }
2712
2713 void G1CollectedHeap::gc_epilogue(bool full) {
2714 // we are at the end of the GC. Total collections has already been increased.
2715 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2716
2717 // FIXME: what is this about?
2718 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2719 // is set.
2720 #if defined(COMPILER2) || INCLUDE_JVMCI
2721 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2722 #endif
2723 // always_do_update_barrier = true;
2724
2725 double start = os::elapsedTime();
2726 resize_all_tlabs();
2727 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2728
2729 allocation_context_stats().update(full);
2730
2731 // We have just completed a GC. Update the soft reference
2732 // policy with the new heap occupancy
2733 Universe::update_heap_info_at_gc();
2734 }
2735
2736 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2737 uint gc_count_before,
2738 bool* succeeded,
2739 GCCause::Cause gc_cause) {
2740 assert_heap_not_locked_and_not_at_safepoint();
2741 VM_G1IncCollectionPause op(gc_count_before,
2742 word_size,
2743 false, /* should_initiate_conc_mark */
2744 g1_policy()->max_pause_time_ms(),
2745 gc_cause);
2746
2747 op.set_allocation_context(AllocationContext::current());
2748 VMThread::execute(&op);
2749
2750 HeapWord* result = op.result();
2751 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2752 assert(result == NULL || ret_succeeded,
2753 "the result should be NULL if the VM did not succeed");
2754 *succeeded = ret_succeeded;
2755
2756 assert_heap_not_locked();
2757 return result;
2758 }
2759
2760 void
2761 G1CollectedHeap::doConcurrentMark() {
2762 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2763 if (!_cmThread->in_progress()) {
2764 _cmThread->set_started();
2765 CGC_lock->notify();
2766 }
2767 }
2768
2769 size_t G1CollectedHeap::pending_card_num() {
2770 size_t extra_cards = 0;
2771 JavaThread *curr = Threads::first();
2772 while (curr != NULL) {
2773 DirtyCardQueue& dcq = curr->dirty_card_queue();
2774 extra_cards += dcq.size();
2775 curr = curr->next();
2776 }
2777 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2778 size_t buffer_size = dcqs.buffer_size();
2779 size_t buffer_num = dcqs.completed_buffers_num();
2780
2781 return buffer_size * buffer_num + extra_cards;
2782 }
2783
2784 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2785 private:
2786 size_t _total_humongous;
2787 size_t _candidate_humongous;
2788
2789 DirtyCardQueue _dcq;
2790
2791 // We don't nominate objects with many remembered set entries, on
2792 // the assumption that such objects are likely still live.
2793 bool is_remset_small(HeapRegion* region) const {
2794 HeapRegionRemSet* const rset = region->rem_set();
2795 return G1EagerReclaimHumongousObjectsWithStaleRefs
2796 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2797 : rset->is_empty();
2798 }
2799
2800 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2801 assert(region->is_starts_humongous(), "Must start a humongous object");
2802
2803 oop obj = oop(region->bottom());
2804
2805 // Dead objects cannot be eager reclaim candidates. Due to class
2806 // unloading it is unsafe to query their classes so we return early.
2807 if (heap->is_obj_dead(obj, region)) {
2808 return false;
2809 }
2810
2811 // Candidate selection must satisfy the following constraints
2812 // while concurrent marking is in progress:
2813 //
2814 // * In order to maintain SATB invariants, an object must not be
2815 // reclaimed if it was allocated before the start of marking and
2816 // has not had its references scanned. Such an object must have
2817 // its references (including type metadata) scanned to ensure no
2818 // live objects are missed by the marking process. Objects
2819 // allocated after the start of concurrent marking don't need to
2820 // be scanned.
2821 //
2822 // * An object must not be reclaimed if it is on the concurrent
2823 // mark stack. Objects allocated after the start of concurrent
2824 // marking are never pushed on the mark stack.
2825 //
2826 // Nominating only objects allocated after the start of concurrent
2827 // marking is sufficient to meet both constraints. This may miss
2828 // some objects that satisfy the constraints, but the marking data
2829 // structures don't support efficiently performing the needed
2830 // additional tests or scrubbing of the mark stack.
2831 //
2832 // However, we presently only nominate is_typeArray() objects.
2833 // A humongous object containing references induces remembered
2834 // set entries on other regions. In order to reclaim such an
2835 // object, those remembered sets would need to be cleaned up.
2836 //
2837 // We also treat is_typeArray() objects specially, allowing them
2838 // to be reclaimed even if allocated before the start of
2839 // concurrent mark. For this we rely on mark stack insertion to
2840 // exclude is_typeArray() objects, preventing reclaiming an object
2841 // that is in the mark stack. We also rely on the metadata for
2842 // such objects to be built-in and so ensured to be kept live.
2843 // Frequent allocation and drop of large binary blobs is an
2844 // important use case for eager reclaim, and this special handling
2845 // may reduce needed headroom.
2846
2847 return obj->is_typeArray() && is_remset_small(region);
2848 }
2849
2850 public:
2851 RegisterHumongousWithInCSetFastTestClosure()
2852 : _total_humongous(0),
2853 _candidate_humongous(0),
2854 _dcq(&JavaThread::dirty_card_queue_set()) {
2855 }
2856
2857 virtual bool doHeapRegion(HeapRegion* r) {
2858 if (!r->is_starts_humongous()) {
2859 return false;
2860 }
2861 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2862
2863 bool is_candidate = humongous_region_is_candidate(g1h, r);
2864 uint rindex = r->hrm_index();
2865 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2866 if (is_candidate) {
2867 _candidate_humongous++;
2868 g1h->register_humongous_region_with_cset(rindex);
2869 // Is_candidate already filters out humongous object with large remembered sets.
2870 // If we have a humongous object with a few remembered sets, we simply flush these
2871 // remembered set entries into the DCQS. That will result in automatic
2872 // re-evaluation of their remembered set entries during the following evacuation
2873 // phase.
2874 if (!r->rem_set()->is_empty()) {
2875 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2876 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2877 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2878 HeapRegionRemSetIterator hrrs(r->rem_set());
2879 size_t card_index;
2880 while (hrrs.has_next(card_index)) {
2881 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2882 // The remembered set might contain references to already freed
2883 // regions. Filter out such entries to avoid failing card table
2884 // verification.
2885 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2886 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2887 *card_ptr = CardTableModRefBS::dirty_card_val();
2888 _dcq.enqueue(card_ptr);
2889 }
2890 }
2891 }
2892 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2893 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2894 hrrs.n_yielded(), r->rem_set()->occupied());
2895 r->rem_set()->clear_locked();
2896 }
2897 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2898 }
2899 _total_humongous++;
2900
2901 return false;
2902 }
2903
2904 size_t total_humongous() const { return _total_humongous; }
2905 size_t candidate_humongous() const { return _candidate_humongous; }
2906
2907 void flush_rem_set_entries() { _dcq.flush(); }
2908 };
2909
2910 void G1CollectedHeap::register_humongous_regions_with_cset() {
2911 if (!G1EagerReclaimHumongousObjects) {
2912 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2913 return;
2914 }
2915 double time = os::elapsed_counter();
2916
2917 // Collect reclaim candidate information and register candidates with cset.
2918 RegisterHumongousWithInCSetFastTestClosure cl;
2919 heap_region_iterate(&cl);
2920
2921 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2922 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2923 cl.total_humongous(),
2924 cl.candidate_humongous());
2925 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2926
2927 // Finally flush all remembered set entries to re-check into the global DCQS.
2928 cl.flush_rem_set_entries();
2929 }
2930
2931 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2932 public:
2933 bool doHeapRegion(HeapRegion* hr) {
2934 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2935 hr->verify_rem_set();
2936 }
2937 return false;
2938 }
2939 };
2940
2941 uint G1CollectedHeap::num_task_queues() const {
2942 return _task_queues->size();
2943 }
2944
2945 #if TASKQUEUE_STATS
2946 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2947 st->print_raw_cr("GC Task Stats");
2948 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2949 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2950 }
2951
2952 void G1CollectedHeap::print_taskqueue_stats() const {
2953 if (!log_is_enabled(Trace, gc, task, stats)) {
2954 return;
2955 }
2956 Log(gc, task, stats) log;
2957 ResourceMark rm;
2958 outputStream* st = log.trace_stream();
2959
2960 print_taskqueue_stats_hdr(st);
2961
2962 TaskQueueStats totals;
2963 const uint n = num_task_queues();
2964 for (uint i = 0; i < n; ++i) {
2965 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2966 totals += task_queue(i)->stats;
2967 }
2968 st->print_raw("tot "); totals.print(st); st->cr();
2969
2970 DEBUG_ONLY(totals.verify());
2971 }
2972
2973 void G1CollectedHeap::reset_taskqueue_stats() {
2974 const uint n = num_task_queues();
2975 for (uint i = 0; i < n; ++i) {
2976 task_queue(i)->stats.reset();
2977 }
2978 }
2979 #endif // TASKQUEUE_STATS
2980
2981 void G1CollectedHeap::wait_for_root_region_scanning() {
2982 double scan_wait_start = os::elapsedTime();
2983 // We have to wait until the CM threads finish scanning the
2984 // root regions as it's the only way to ensure that all the
2985 // objects on them have been correctly scanned before we start
2986 // moving them during the GC.
2987 bool waited = _cm->root_regions()->wait_until_scan_finished();
2988 double wait_time_ms = 0.0;
2989 if (waited) {
2990 double scan_wait_end = os::elapsedTime();
2991 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2992 }
2993 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2994 }
2995
2996 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2997 private:
2998 G1HRPrinter* _hr_printer;
2999 public:
3000 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
3001
3002 virtual bool doHeapRegion(HeapRegion* r) {
3003 _hr_printer->cset(r);
3004 return false;
3005 }
3006 };
3007
3008 void G1CollectedHeap::start_new_collection_set() {
3009 collection_set()->start_incremental_building();
3010
3011 clear_cset_fast_test();
3012
3013 guarantee(_eden.length() == 0, "eden should have been cleared");
3014 g1_policy()->transfer_survivors_to_cset(survivor());
3015 }
3016
3017 bool
3018 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3019 assert_at_safepoint(true /* should_be_vm_thread */);
3020 guarantee(!is_gc_active(), "collection is not reentrant");
3021
3022 if (GCLocker::check_active_before_gc()) {
3023 return false;
3024 }
3025
3026 _gc_timer_stw->register_gc_start();
3027
3028 GCIdMark gc_id_mark;
3029 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3030
3031 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3032 ResourceMark rm;
3033
3034 g1_policy()->note_gc_start();
3035
3036 wait_for_root_region_scanning();
3037
3038 print_heap_before_gc();
3039 print_heap_regions();
3040 trace_heap_before_gc(_gc_tracer_stw);
3041
3042 _verifier->verify_region_sets_optional();
3043 _verifier->verify_dirty_young_regions();
3044
3045 // We should not be doing initial mark unless the conc mark thread is running
3046 if (!_cmThread->should_terminate()) {
3047 // This call will decide whether this pause is an initial-mark
3048 // pause. If it is, during_initial_mark_pause() will return true
3049 // for the duration of this pause.
3050 g1_policy()->decide_on_conc_mark_initiation();
3051 }
3052
3053 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3054 assert(!collector_state()->during_initial_mark_pause() ||
3055 collector_state()->gcs_are_young(), "sanity");
3056
3057 // We also do not allow mixed GCs during marking.
3058 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3059
3060 // Record whether this pause is an initial mark. When the current
3061 // thread has completed its logging output and it's safe to signal
3062 // the CM thread, the flag's value in the policy has been reset.
3063 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3064
3065 // Inner scope for scope based logging, timers, and stats collection
3066 {
3067 EvacuationInfo evacuation_info;
3068
3069 if (collector_state()->during_initial_mark_pause()) {
3070 // We are about to start a marking cycle, so we increment the
3071 // full collection counter.
3072 increment_old_marking_cycles_started();
3073 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3074 }
3075
3076 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3077
3078 GCTraceCPUTime tcpu;
3079
3080 FormatBuffer<> gc_string("Pause ");
3081 if (collector_state()->during_initial_mark_pause()) {
3082 gc_string.append("Initial Mark");
3083 } else if (collector_state()->gcs_are_young()) {
3084 gc_string.append("Young");
3085 } else {
3086 gc_string.append("Mixed");
3087 }
3088 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3089
3090 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3091 workers()->active_workers(),
3092 Threads::number_of_non_daemon_threads());
3093 workers()->update_active_workers(active_workers);
3094 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3095
3096 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3097 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3098
3099 // If the secondary_free_list is not empty, append it to the
3100 // free_list. No need to wait for the cleanup operation to finish;
3101 // the region allocation code will check the secondary_free_list
3102 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3103 // set, skip this step so that the region allocation code has to
3104 // get entries from the secondary_free_list.
3105 if (!G1StressConcRegionFreeing) {
3106 append_secondary_free_list_if_not_empty_with_lock();
3107 }
3108
3109 G1HeapTransition heap_transition(this);
3110 size_t heap_used_bytes_before_gc = used();
3111
3112 // Don't dynamically change the number of GC threads this early. A value of
3113 // 0 is used to indicate serial work. When parallel work is done,
3114 // it will be set.
3115
3116 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3117 IsGCActiveMark x;
3118
3119 gc_prologue(false);
3120 increment_total_collections(false /* full gc */);
3121 increment_gc_time_stamp();
3122
3123 if (VerifyRememberedSets) {
3124 log_info(gc, verify)("[Verifying RemSets before GC]");
3125 VerifyRegionRemSetClosure v_cl;
3126 heap_region_iterate(&v_cl);
3127 }
3128
3129 _verifier->verify_before_gc();
3130
3131 _verifier->check_bitmaps("GC Start");
3132
3133 #if defined(COMPILER2) || INCLUDE_JVMCI
3134 DerivedPointerTable::clear();
3135 #endif
3136
3137 // Please see comment in g1CollectedHeap.hpp and
3138 // G1CollectedHeap::ref_processing_init() to see how
3139 // reference processing currently works in G1.
3140
3141 // Enable discovery in the STW reference processor
3142 if (g1_policy()->should_process_references()) {
3143 ref_processor_stw()->enable_discovery();
3144 } else {
3145 ref_processor_stw()->disable_discovery();
3146 }
3147
3148 {
3149 // We want to temporarily turn off discovery by the
3150 // CM ref processor, if necessary, and turn it back on
3151 // on again later if we do. Using a scoped
3152 // NoRefDiscovery object will do this.
3153 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3154
3155 // Forget the current alloc region (we might even choose it to be part
3156 // of the collection set!).
3157 _allocator->release_mutator_alloc_region();
3158
3159 // This timing is only used by the ergonomics to handle our pause target.
3160 // It is unclear why this should not include the full pause. We will
3161 // investigate this in CR 7178365.
3162 //
3163 // Preserving the old comment here if that helps the investigation:
3164 //
3165 // The elapsed time induced by the start time below deliberately elides
3166 // the possible verification above.
3167 double sample_start_time_sec = os::elapsedTime();
3168
3169 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3170
3171 if (collector_state()->during_initial_mark_pause()) {
3172 concurrent_mark()->checkpointRootsInitialPre();
3173 }
3174
3175 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3176
3177 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3178
3179 // Make sure the remembered sets are up to date. This needs to be
3180 // done before register_humongous_regions_with_cset(), because the
3181 // remembered sets are used there to choose eager reclaim candidates.
3182 // If the remembered sets are not up to date we might miss some
3183 // entries that need to be handled.
3184 g1_rem_set()->cleanupHRRS();
3185
3186 register_humongous_regions_with_cset();
3187
3188 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3189
3190 // We call this after finalize_cset() to
3191 // ensure that the CSet has been finalized.
3192 _cm->verify_no_cset_oops();
3193
3194 if (_hr_printer.is_active()) {
3195 G1PrintCollectionSetClosure cl(&_hr_printer);
3196 _collection_set.iterate(&cl);
3197 }
3198
3199 // Initialize the GC alloc regions.
3200 _allocator->init_gc_alloc_regions(evacuation_info);
3201
3202 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3203 pre_evacuate_collection_set();
3204
3205 // Actually do the work...
3206 evacuate_collection_set(evacuation_info, &per_thread_states);
3207
3208 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3209
3210 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3211 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3212
3213 eagerly_reclaim_humongous_regions();
3214
3215 record_obj_copy_mem_stats();
3216 _survivor_evac_stats.adjust_desired_plab_sz();
3217 _old_evac_stats.adjust_desired_plab_sz();
3218
3219 double start = os::elapsedTime();
3220 start_new_collection_set();
3221 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3222
3223 if (evacuation_failed()) {
3224 set_used(recalculate_used());
3225 if (_archive_allocator != NULL) {
3226 _archive_allocator->clear_used();
3227 }
3228 for (uint i = 0; i < ParallelGCThreads; i++) {
3229 if (_evacuation_failed_info_array[i].has_failed()) {
3230 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3231 }
3232 }
3233 } else {
3234 // The "used" of the the collection set have already been subtracted
3235 // when they were freed. Add in the bytes evacuated.
3236 increase_used(g1_policy()->bytes_copied_during_gc());
3237 }
3238
3239 if (collector_state()->during_initial_mark_pause()) {
3240 // We have to do this before we notify the CM threads that
3241 // they can start working to make sure that all the
3242 // appropriate initialization is done on the CM object.
3243 concurrent_mark()->checkpointRootsInitialPost();
3244 collector_state()->set_mark_in_progress(true);
3245 // Note that we don't actually trigger the CM thread at
3246 // this point. We do that later when we're sure that
3247 // the current thread has completed its logging output.
3248 }
3249
3250 allocate_dummy_regions();
3251
3252 _allocator->init_mutator_alloc_region();
3253
3254 {
3255 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3256 if (expand_bytes > 0) {
3257 size_t bytes_before = capacity();
3258 // No need for an ergo logging here,
3259 // expansion_amount() does this when it returns a value > 0.
3260 double expand_ms;
3261 if (!expand(expand_bytes, _workers, &expand_ms)) {
3262 // We failed to expand the heap. Cannot do anything about it.
3263 }
3264 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3265 }
3266 }
3267
3268 // We redo the verification but now wrt to the new CSet which
3269 // has just got initialized after the previous CSet was freed.
3270 _cm->verify_no_cset_oops();
3271
3272 // This timing is only used by the ergonomics to handle our pause target.
3273 // It is unclear why this should not include the full pause. We will
3274 // investigate this in CR 7178365.
3275 double sample_end_time_sec = os::elapsedTime();
3276 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3277 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3278 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3279
3280 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3281 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3282
3283 MemoryService::track_memory_usage();
3284
3285 // In prepare_for_verify() below we'll need to scan the deferred
3286 // update buffers to bring the RSets up-to-date if
3287 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3288 // the update buffers we'll probably need to scan cards on the
3289 // regions we just allocated to (i.e., the GC alloc
3290 // regions). However, during the last GC we called
3291 // set_saved_mark() on all the GC alloc regions, so card
3292 // scanning might skip the [saved_mark_word()...top()] area of
3293 // those regions (i.e., the area we allocated objects into
3294 // during the last GC). But it shouldn't. Given that
3295 // saved_mark_word() is conditional on whether the GC time stamp
3296 // on the region is current or not, by incrementing the GC time
3297 // stamp here we invalidate all the GC time stamps on all the
3298 // regions and saved_mark_word() will simply return top() for
3299 // all the regions. This is a nicer way of ensuring this rather
3300 // than iterating over the regions and fixing them. In fact, the
3301 // GC time stamp increment here also ensures that
3302 // saved_mark_word() will return top() between pauses, i.e.,
3303 // during concurrent refinement. So we don't need the
3304 // is_gc_active() check to decided which top to use when
3305 // scanning cards (see CR 7039627).
3306 increment_gc_time_stamp();
3307
3308 if (VerifyRememberedSets) {
3309 log_info(gc, verify)("[Verifying RemSets after GC]");
3310 VerifyRegionRemSetClosure v_cl;
3311 heap_region_iterate(&v_cl);
3312 }
3313
3314 _verifier->verify_after_gc();
3315 _verifier->check_bitmaps("GC End");
3316
3317 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3318 ref_processor_stw()->verify_no_references_recorded();
3319
3320 // CM reference discovery will be re-enabled if necessary.
3321 }
3322
3323 #ifdef TRACESPINNING
3324 ParallelTaskTerminator::print_termination_counts();
3325 #endif
3326
3327 gc_epilogue(false);
3328 }
3329
3330 // Print the remainder of the GC log output.
3331 if (evacuation_failed()) {
3332 log_info(gc)("To-space exhausted");
3333 }
3334
3335 g1_policy()->print_phases();
3336 heap_transition.print();
3337
3338 // It is not yet to safe to tell the concurrent mark to
3339 // start as we have some optional output below. We don't want the
3340 // output from the concurrent mark thread interfering with this
3341 // logging output either.
3342
3343 _hrm.verify_optional();
3344 _verifier->verify_region_sets_optional();
3345
3346 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3347 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3348
3349 print_heap_after_gc();
3350 print_heap_regions();
3351 trace_heap_after_gc(_gc_tracer_stw);
3352
3353 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3354 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3355 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3356 // before any GC notifications are raised.
3357 g1mm()->update_sizes();
3358
3359 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3360 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3361 _gc_timer_stw->register_gc_end();
3362 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3363 }
3364 // It should now be safe to tell the concurrent mark thread to start
3365 // without its logging output interfering with the logging output
3366 // that came from the pause.
3367
3368 if (should_start_conc_mark) {
3369 // CAUTION: after the doConcurrentMark() call below,
3370 // the concurrent marking thread(s) could be running
3371 // concurrently with us. Make sure that anything after
3372 // this point does not assume that we are the only GC thread
3373 // running. Note: of course, the actual marking work will
3374 // not start until the safepoint itself is released in
3375 // SuspendibleThreadSet::desynchronize().
3376 doConcurrentMark();
3377 }
3378
3379 return true;
3380 }
3381
3382 void G1CollectedHeap::remove_self_forwarding_pointers() {
3383 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3384 workers()->run_task(&rsfp_task);
3385 }
3386
3387 void G1CollectedHeap::restore_after_evac_failure() {
3388 double remove_self_forwards_start = os::elapsedTime();
3389
3390 remove_self_forwarding_pointers();
3391 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3392 _preserved_marks_set.restore(&task_executor);
3393
3394 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3395 }
3396
3397 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3398 if (!_evacuation_failed) {
3399 _evacuation_failed = true;
3400 }
3401
3402 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3403 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3404 }
3405
3406 bool G1ParEvacuateFollowersClosure::offer_termination() {
3407 G1ParScanThreadState* const pss = par_scan_state();
3408 start_term_time();
3409 const bool res = terminator()->offer_termination();
3410 end_term_time();
3411 return res;
3412 }
3413
3414 void G1ParEvacuateFollowersClosure::do_void() {
3415 G1ParScanThreadState* const pss = par_scan_state();
3416 pss->trim_queue();
3417 do {
3418 pss->steal_and_trim_queue(queues());
3419 } while (!offer_termination());
3420 }
3421
3422 class G1ParTask : public AbstractGangTask {
3423 protected:
3424 G1CollectedHeap* _g1h;
3425 G1ParScanThreadStateSet* _pss;
3426 RefToScanQueueSet* _queues;
3427 G1RootProcessor* _root_processor;
3428 ParallelTaskTerminator _terminator;
3429 uint _n_workers;
3430
3431 public:
3432 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3433 : AbstractGangTask("G1 collection"),
3434 _g1h(g1h),
3435 _pss(per_thread_states),
3436 _queues(task_queues),
3437 _root_processor(root_processor),
3438 _terminator(n_workers, _queues),
3439 _n_workers(n_workers)
3440 {}
3441
3442 void work(uint worker_id) {
3443 if (worker_id >= _n_workers) return; // no work needed this round
3444
3445 double start_sec = os::elapsedTime();
3446 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3447
3448 {
3449 ResourceMark rm;
3450 HandleMark hm;
3451
3452 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3453
3454 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3455 pss->set_ref_processor(rp);
3456
3457 double start_strong_roots_sec = os::elapsedTime();
3458
3459 _root_processor->evacuate_roots(pss->closures(), worker_id);
3460
3461 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3462
3463 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3464 // treating the nmethods visited to act as roots for concurrent marking.
3465 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3466 // objects copied by the current evacuation.
3467 _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3468 pss->closures()->weak_codeblobs(),
3469 worker_id);
3470
3471 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3472
3473 double term_sec = 0.0;
3474 size_t evac_term_attempts = 0;
3475 {
3476 double start = os::elapsedTime();
3477 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3478 evac.do_void();
3479
3480 evac_term_attempts = evac.term_attempts();
3481 term_sec = evac.term_time();
3482 double elapsed_sec = os::elapsedTime() - start;
3483 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3484 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3485 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3486 }
3487
3488 assert(pss->queue_is_empty(), "should be empty");
3489
3490 if (log_is_enabled(Debug, gc, task, stats)) {
3491 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3492 size_t lab_waste;
3493 size_t lab_undo_waste;
3494 pss->waste(lab_waste, lab_undo_waste);
3495 _g1h->print_termination_stats(worker_id,
3496 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3497 strong_roots_sec * 1000.0, /* strong roots time */
3498 term_sec * 1000.0, /* evac term time */
3499 evac_term_attempts, /* evac term attempts */
3500 lab_waste, /* alloc buffer waste */
3501 lab_undo_waste /* undo waste */
3502 );
3503 }
3504
3505 // Close the inner scope so that the ResourceMark and HandleMark
3506 // destructors are executed here and are included as part of the
3507 // "GC Worker Time".
3508 }
3509 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3510 }
3511 };
3512
3513 void G1CollectedHeap::print_termination_stats_hdr() {
3514 log_debug(gc, task, stats)("GC Termination Stats");
3515 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3516 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3517 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3518 }
3519
3520 void G1CollectedHeap::print_termination_stats(uint worker_id,
3521 double elapsed_ms,
3522 double strong_roots_ms,
3523 double term_ms,
3524 size_t term_attempts,
3525 size_t alloc_buffer_waste,
3526 size_t undo_waste) const {
3527 log_debug(gc, task, stats)
3528 ("%3d %9.2f %9.2f %6.2f "
3529 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3530 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3531 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3532 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3533 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3534 alloc_buffer_waste * HeapWordSize / K,
3535 undo_waste * HeapWordSize / K);
3536 }
3537
3538 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3539 private:
3540 BoolObjectClosure* _is_alive;
3541 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3542
3543 int _initial_string_table_size;
3544 int _initial_symbol_table_size;
3545
3546 bool _process_strings;
3547 int _strings_processed;
3548 int _strings_removed;
3549
3550 bool _process_symbols;
3551 int _symbols_processed;
3552 int _symbols_removed;
3553
3554 bool _process_string_dedup;
3555
3556 public:
3557 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3558 AbstractGangTask("String/Symbol Unlinking"),
3559 _is_alive(is_alive),
3560 _dedup_closure(is_alive, NULL, false),
3561 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3562 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3563 _process_string_dedup(process_string_dedup) {
3564
3565 _initial_string_table_size = StringTable::the_table()->table_size();
3566 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3567 if (process_strings) {
3568 StringTable::clear_parallel_claimed_index();
3569 }
3570 if (process_symbols) {
3571 SymbolTable::clear_parallel_claimed_index();
3572 }
3573 }
3574
3575 ~G1StringAndSymbolCleaningTask() {
3576 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3577 "claim value %d after unlink less than initial string table size %d",
3578 StringTable::parallel_claimed_index(), _initial_string_table_size);
3579 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3580 "claim value %d after unlink less than initial symbol table size %d",
3581 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3582
3583 log_info(gc, stringtable)(
3584 "Cleaned string and symbol table, "
3585 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3586 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3587 strings_processed(), strings_removed(),
3588 symbols_processed(), symbols_removed());
3589 }
3590
3591 void work(uint worker_id) {
3592 int strings_processed = 0;
3593 int strings_removed = 0;
3594 int symbols_processed = 0;
3595 int symbols_removed = 0;
3596 if (_process_strings) {
3597 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3598 Atomic::add(strings_processed, &_strings_processed);
3599 Atomic::add(strings_removed, &_strings_removed);
3600 }
3601 if (_process_symbols) {
3602 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3603 Atomic::add(symbols_processed, &_symbols_processed);
3604 Atomic::add(symbols_removed, &_symbols_removed);
3605 }
3606 if (_process_string_dedup) {
3607 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3608 }
3609 }
3610
3611 size_t strings_processed() const { return (size_t)_strings_processed; }
3612 size_t strings_removed() const { return (size_t)_strings_removed; }
3613
3614 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3615 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3616 };
3617
3618 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3619 private:
3620 static Monitor* _lock;
3621
3622 BoolObjectClosure* const _is_alive;
3623 const bool _unloading_occurred;
3624 const uint _num_workers;
3625
3626 // Variables used to claim nmethods.
3627 CompiledMethod* _first_nmethod;
3628 volatile CompiledMethod* _claimed_nmethod;
3629
3630 // The list of nmethods that need to be processed by the second pass.
3631 volatile CompiledMethod* _postponed_list;
3632 volatile uint _num_entered_barrier;
3633
3634 public:
3635 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3636 _is_alive(is_alive),
3637 _unloading_occurred(unloading_occurred),
3638 _num_workers(num_workers),
3639 _first_nmethod(NULL),
3640 _claimed_nmethod(NULL),
3641 _postponed_list(NULL),
3642 _num_entered_barrier(0)
3643 {
3644 CompiledMethod::increase_unloading_clock();
3645 // Get first alive nmethod
3646 CompiledMethodIterator iter = CompiledMethodIterator();
3647 if(iter.next_alive()) {
3648 _first_nmethod = iter.method();
3649 }
3650 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3651 }
3652
3653 ~G1CodeCacheUnloadingTask() {
3654 CodeCache::verify_clean_inline_caches();
3655
3656 CodeCache::set_needs_cache_clean(false);
3657 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3658
3659 CodeCache::verify_icholder_relocations();
3660 }
3661
3662 private:
3663 void add_to_postponed_list(CompiledMethod* nm) {
3664 CompiledMethod* old;
3665 do {
3666 old = (CompiledMethod*)_postponed_list;
3667 nm->set_unloading_next(old);
3668 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3669 }
3670
3671 void clean_nmethod(CompiledMethod* nm) {
3672 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3673
3674 if (postponed) {
3675 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3676 add_to_postponed_list(nm);
3677 }
3678
3679 // Mark that this thread has been cleaned/unloaded.
3680 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3681 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3682 }
3683
3684 void clean_nmethod_postponed(CompiledMethod* nm) {
3685 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3686 }
3687
3688 static const int MaxClaimNmethods = 16;
3689
3690 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3691 CompiledMethod* first;
3692 CompiledMethodIterator last;
3693
3694 do {
3695 *num_claimed_nmethods = 0;
3696
3697 first = (CompiledMethod*)_claimed_nmethod;
3698 last = CompiledMethodIterator(first);
3699
3700 if (first != NULL) {
3701
3702 for (int i = 0; i < MaxClaimNmethods; i++) {
3703 if (!last.next_alive()) {
3704 break;
3705 }
3706 claimed_nmethods[i] = last.method();
3707 (*num_claimed_nmethods)++;
3708 }
3709 }
3710
3711 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3712 }
3713
3714 CompiledMethod* claim_postponed_nmethod() {
3715 CompiledMethod* claim;
3716 CompiledMethod* next;
3717
3718 do {
3719 claim = (CompiledMethod*)_postponed_list;
3720 if (claim == NULL) {
3721 return NULL;
3722 }
3723
3724 next = claim->unloading_next();
3725
3726 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3727
3728 return claim;
3729 }
3730
3731 public:
3732 // Mark that we're done with the first pass of nmethod cleaning.
3733 void barrier_mark(uint worker_id) {
3734 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3735 _num_entered_barrier++;
3736 if (_num_entered_barrier == _num_workers) {
3737 ml.notify_all();
3738 }
3739 }
3740
3741 // See if we have to wait for the other workers to
3742 // finish their first-pass nmethod cleaning work.
3743 void barrier_wait(uint worker_id) {
3744 if (_num_entered_barrier < _num_workers) {
3745 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3746 while (_num_entered_barrier < _num_workers) {
3747 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3748 }
3749 }
3750 }
3751
3752 // Cleaning and unloading of nmethods. Some work has to be postponed
3753 // to the second pass, when we know which nmethods survive.
3754 void work_first_pass(uint worker_id) {
3755 // The first nmethods is claimed by the first worker.
3756 if (worker_id == 0 && _first_nmethod != NULL) {
3757 clean_nmethod(_first_nmethod);
3758 _first_nmethod = NULL;
3759 }
3760
3761 int num_claimed_nmethods;
3762 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3763
3764 while (true) {
3765 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3766
3767 if (num_claimed_nmethods == 0) {
3768 break;
3769 }
3770
3771 for (int i = 0; i < num_claimed_nmethods; i++) {
3772 clean_nmethod(claimed_nmethods[i]);
3773 }
3774 }
3775 }
3776
3777 void work_second_pass(uint worker_id) {
3778 CompiledMethod* nm;
3779 // Take care of postponed nmethods.
3780 while ((nm = claim_postponed_nmethod()) != NULL) {
3781 clean_nmethod_postponed(nm);
3782 }
3783 }
3784 };
3785
3786 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3787
3788 class G1KlassCleaningTask : public StackObj {
3789 BoolObjectClosure* _is_alive;
3790 volatile jint _clean_klass_tree_claimed;
3791 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3792
3793 public:
3794 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3795 _is_alive(is_alive),
3796 _clean_klass_tree_claimed(0),
3797 _klass_iterator() {
3798 }
3799
3800 private:
3801 bool claim_clean_klass_tree_task() {
3802 if (_clean_klass_tree_claimed) {
3803 return false;
3804 }
3805
3806 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3807 }
3808
3809 InstanceKlass* claim_next_klass() {
3810 Klass* klass;
3811 do {
3812 klass =_klass_iterator.next_klass();
3813 } while (klass != NULL && !klass->is_instance_klass());
3814
3815 // this can be null so don't call InstanceKlass::cast
3816 return static_cast<InstanceKlass*>(klass);
3817 }
3818
3819 public:
3820
3821 void clean_klass(InstanceKlass* ik) {
3822 ik->clean_weak_instanceklass_links(_is_alive);
3823 }
3824
3825 void work() {
3826 ResourceMark rm;
3827
3828 // One worker will clean the subklass/sibling klass tree.
3829 if (claim_clean_klass_tree_task()) {
3830 Klass::clean_subklass_tree(_is_alive);
3831 }
3832
3833 // All workers will help cleaning the classes,
3834 InstanceKlass* klass;
3835 while ((klass = claim_next_klass()) != NULL) {
3836 clean_klass(klass);
3837 }
3838 }
3839 };
3840
3841 class G1ResolvedMethodCleaningTask : public StackObj {
3842 BoolObjectClosure* _is_alive;
3843 volatile jint _resolved_method_task_claimed;
3844 public:
3845 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3846 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3847
3848 bool claim_resolved_method_task() {
3849 if (_resolved_method_task_claimed) {
3850 return false;
3851 }
3852 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3853 }
3854
3855 // These aren't big, one thread can do it all.
3856 void work() {
3857 if (claim_resolved_method_task()) {
3858 ResolvedMethodTable::unlink(_is_alive);
3859 }
3860 }
3861 };
3862
3863
3864 // To minimize the remark pause times, the tasks below are done in parallel.
3865 class G1ParallelCleaningTask : public AbstractGangTask {
3866 private:
3867 G1StringAndSymbolCleaningTask _string_symbol_task;
3868 G1CodeCacheUnloadingTask _code_cache_task;
3869 G1KlassCleaningTask _klass_cleaning_task;
3870 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3871
3872 public:
3873 // The constructor is run in the VMThread.
3874 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3875 AbstractGangTask("Parallel Cleaning"),
3876 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3877 _code_cache_task(num_workers, is_alive, unloading_occurred),
3878 _klass_cleaning_task(is_alive),
3879 _resolved_method_cleaning_task(is_alive) {
3880 }
3881
3882 // The parallel work done by all worker threads.
3883 void work(uint worker_id) {
3884 // Do first pass of code cache cleaning.
3885 _code_cache_task.work_first_pass(worker_id);
3886
3887 // Let the threads mark that the first pass is done.
3888 _code_cache_task.barrier_mark(worker_id);
3889
3890 // Clean the Strings and Symbols.
3891 _string_symbol_task.work(worker_id);
3892
3893 // Clean unreferenced things in the ResolvedMethodTable
3894 _resolved_method_cleaning_task.work();
3895
3896 // Wait for all workers to finish the first code cache cleaning pass.
3897 _code_cache_task.barrier_wait(worker_id);
3898
3899 // Do the second code cache cleaning work, which realize on
3900 // the liveness information gathered during the first pass.
3901 _code_cache_task.work_second_pass(worker_id);
3902
3903 // Clean all klasses that were not unloaded.
3904 _klass_cleaning_task.work();
3905 }
3906 };
3907
3908
3909 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3910 bool class_unloading_occurred) {
3911 uint n_workers = workers()->active_workers();
3912
3913 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3914 workers()->run_task(&g1_unlink_task);
3915 }
3916
3917 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3918 bool process_strings,
3919 bool process_symbols,
3920 bool process_string_dedup) {
3921 if (!process_strings && !process_symbols && !process_string_dedup) {
3922 // Nothing to clean.
3923 return;
3924 }
3925
3926 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3927 workers()->run_task(&g1_unlink_task);
3928
3929 }
3930
3931 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3932 private:
3933 DirtyCardQueueSet* _queue;
3934 G1CollectedHeap* _g1h;
3935 public:
3936 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3937 _queue(queue), _g1h(g1h) { }
3938
3939 virtual void work(uint worker_id) {
3940 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3941 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3942
3943 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3944 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3945
3946 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3947 }
3948 };
3949
3950 void G1CollectedHeap::redirty_logged_cards() {
3951 double redirty_logged_cards_start = os::elapsedTime();
3952
3953 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3954 dirty_card_queue_set().reset_for_par_iteration();
3955 workers()->run_task(&redirty_task);
3956
3957 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3958 dcq.merge_bufferlists(&dirty_card_queue_set());
3959 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3960
3961 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3962 }
3963
3964 // Weak Reference Processing support
3965
3966 // An always "is_alive" closure that is used to preserve referents.
3967 // If the object is non-null then it's alive. Used in the preservation
3968 // of referent objects that are pointed to by reference objects
3969 // discovered by the CM ref processor.
3970 class G1AlwaysAliveClosure: public BoolObjectClosure {
3971 G1CollectedHeap* _g1;
3972 public:
3973 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3974 bool do_object_b(oop p) {
3975 if (p != NULL) {
3976 return true;
3977 }
3978 return false;
3979 }
3980 };
3981
3982 bool G1STWIsAliveClosure::do_object_b(oop p) {
3983 // An object is reachable if it is outside the collection set,
3984 // or is inside and copied.
3985 return !_g1->is_in_cset(p) || p->is_forwarded();
3986 }
3987
3988 // Non Copying Keep Alive closure
3989 class G1KeepAliveClosure: public OopClosure {
3990 G1CollectedHeap* _g1;
3991 public:
3992 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3993 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3994 void do_oop(oop* p) {
3995 oop obj = *p;
3996 assert(obj != NULL, "the caller should have filtered out NULL values");
3997
3998 const InCSetState cset_state = _g1->in_cset_state(obj);
3999 if (!cset_state.is_in_cset_or_humongous()) {
4000 return;
4001 }
4002 if (cset_state.is_in_cset()) {
4003 assert( obj->is_forwarded(), "invariant" );
4004 *p = obj->forwardee();
4005 } else {
4006 assert(!obj->is_forwarded(), "invariant" );
4007 assert(cset_state.is_humongous(),
4008 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4009 _g1->set_humongous_is_live(obj);
4010 }
4011 }
4012 };
4013
4014 // Copying Keep Alive closure - can be called from both
4015 // serial and parallel code as long as different worker
4016 // threads utilize different G1ParScanThreadState instances
4017 // and different queues.
4018
4019 class G1CopyingKeepAliveClosure: public OopClosure {
4020 G1CollectedHeap* _g1h;
4021 OopClosure* _copy_non_heap_obj_cl;
4022 G1ParScanThreadState* _par_scan_state;
4023
4024 public:
4025 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4026 OopClosure* non_heap_obj_cl,
4027 G1ParScanThreadState* pss):
4028 _g1h(g1h),
4029 _copy_non_heap_obj_cl(non_heap_obj_cl),
4030 _par_scan_state(pss)
4031 {}
4032
4033 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4034 virtual void do_oop( oop* p) { do_oop_work(p); }
4035
4036 template <class T> void do_oop_work(T* p) {
4037 oop obj = oopDesc::load_decode_heap_oop(p);
4038
4039 if (_g1h->is_in_cset_or_humongous(obj)) {
4040 // If the referent object has been forwarded (either copied
4041 // to a new location or to itself in the event of an
4042 // evacuation failure) then we need to update the reference
4043 // field and, if both reference and referent are in the G1
4044 // heap, update the RSet for the referent.
4045 //
4046 // If the referent has not been forwarded then we have to keep
4047 // it alive by policy. Therefore we have copy the referent.
4048 //
4049 // If the reference field is in the G1 heap then we can push
4050 // on the PSS queue. When the queue is drained (after each
4051 // phase of reference processing) the object and it's followers
4052 // will be copied, the reference field set to point to the
4053 // new location, and the RSet updated. Otherwise we need to
4054 // use the the non-heap or metadata closures directly to copy
4055 // the referent object and update the pointer, while avoiding
4056 // updating the RSet.
4057
4058 if (_g1h->is_in_g1_reserved(p)) {
4059 _par_scan_state->push_on_queue(p);
4060 } else {
4061 assert(!Metaspace::contains((const void*)p),
4062 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4063 _copy_non_heap_obj_cl->do_oop(p);
4064 }
4065 }
4066 }
4067 };
4068
4069 // Serial drain queue closure. Called as the 'complete_gc'
4070 // closure for each discovered list in some of the
4071 // reference processing phases.
4072
4073 class G1STWDrainQueueClosure: public VoidClosure {
4074 protected:
4075 G1CollectedHeap* _g1h;
4076 G1ParScanThreadState* _par_scan_state;
4077
4078 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4079
4080 public:
4081 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4082 _g1h(g1h),
4083 _par_scan_state(pss)
4084 { }
4085
4086 void do_void() {
4087 G1ParScanThreadState* const pss = par_scan_state();
4088 pss->trim_queue();
4089 }
4090 };
4091
4092 // Parallel Reference Processing closures
4093
4094 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4095 // processing during G1 evacuation pauses.
4096
4097 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4098 private:
4099 G1CollectedHeap* _g1h;
4100 G1ParScanThreadStateSet* _pss;
4101 RefToScanQueueSet* _queues;
4102 WorkGang* _workers;
4103 uint _active_workers;
4104
4105 public:
4106 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4107 G1ParScanThreadStateSet* per_thread_states,
4108 WorkGang* workers,
4109 RefToScanQueueSet *task_queues,
4110 uint n_workers) :
4111 _g1h(g1h),
4112 _pss(per_thread_states),
4113 _queues(task_queues),
4114 _workers(workers),
4115 _active_workers(n_workers)
4116 {
4117 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4118 }
4119
4120 // Executes the given task using concurrent marking worker threads.
4121 virtual void execute(ProcessTask& task);
4122 virtual void execute(EnqueueTask& task);
4123 };
4124
4125 // Gang task for possibly parallel reference processing
4126
4127 class G1STWRefProcTaskProxy: public AbstractGangTask {
4128 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4129 ProcessTask& _proc_task;
4130 G1CollectedHeap* _g1h;
4131 G1ParScanThreadStateSet* _pss;
4132 RefToScanQueueSet* _task_queues;
4133 ParallelTaskTerminator* _terminator;
4134
4135 public:
4136 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4137 G1CollectedHeap* g1h,
4138 G1ParScanThreadStateSet* per_thread_states,
4139 RefToScanQueueSet *task_queues,
4140 ParallelTaskTerminator* terminator) :
4141 AbstractGangTask("Process reference objects in parallel"),
4142 _proc_task(proc_task),
4143 _g1h(g1h),
4144 _pss(per_thread_states),
4145 _task_queues(task_queues),
4146 _terminator(terminator)
4147 {}
4148
4149 virtual void work(uint worker_id) {
4150 // The reference processing task executed by a single worker.
4151 ResourceMark rm;
4152 HandleMark hm;
4153
4154 G1STWIsAliveClosure is_alive(_g1h);
4155
4156 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4157 pss->set_ref_processor(NULL);
4158
4159 // Keep alive closure.
4160 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4161
4162 // Complete GC closure
4163 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4164
4165 // Call the reference processing task's work routine.
4166 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4167
4168 // Note we cannot assert that the refs array is empty here as not all
4169 // of the processing tasks (specifically phase2 - pp2_work) execute
4170 // the complete_gc closure (which ordinarily would drain the queue) so
4171 // the queue may not be empty.
4172 }
4173 };
4174
4175 // Driver routine for parallel reference processing.
4176 // Creates an instance of the ref processing gang
4177 // task and has the worker threads execute it.
4178 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4179 assert(_workers != NULL, "Need parallel worker threads.");
4180
4181 ParallelTaskTerminator terminator(_active_workers, _queues);
4182 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4183
4184 _workers->run_task(&proc_task_proxy);
4185 }
4186
4187 // Gang task for parallel reference enqueueing.
4188
4189 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4190 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4191 EnqueueTask& _enq_task;
4192
4193 public:
4194 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4195 AbstractGangTask("Enqueue reference objects in parallel"),
4196 _enq_task(enq_task)
4197 { }
4198
4199 virtual void work(uint worker_id) {
4200 _enq_task.work(worker_id);
4201 }
4202 };
4203
4204 // Driver routine for parallel reference enqueueing.
4205 // Creates an instance of the ref enqueueing gang
4206 // task and has the worker threads execute it.
4207
4208 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4209 assert(_workers != NULL, "Need parallel worker threads.");
4210
4211 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4212
4213 _workers->run_task(&enq_task_proxy);
4214 }
4215
4216 // End of weak reference support closures
4217
4218 // Abstract task used to preserve (i.e. copy) any referent objects
4219 // that are in the collection set and are pointed to by reference
4220 // objects discovered by the CM ref processor.
4221
4222 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4223 protected:
4224 G1CollectedHeap* _g1h;
4225 G1ParScanThreadStateSet* _pss;
4226 RefToScanQueueSet* _queues;
4227 ParallelTaskTerminator _terminator;
4228 uint _n_workers;
4229
4230 public:
4231 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4232 AbstractGangTask("ParPreserveCMReferents"),
4233 _g1h(g1h),
4234 _pss(per_thread_states),
4235 _queues(task_queues),
4236 _terminator(workers, _queues),
4237 _n_workers(workers)
4238 {
4239 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4240 }
4241
4242 void work(uint worker_id) {
4243 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4244
4245 ResourceMark rm;
4246 HandleMark hm;
4247
4248 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4249 pss->set_ref_processor(NULL);
4250 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4251
4252 // Is alive closure
4253 G1AlwaysAliveClosure always_alive(_g1h);
4254
4255 // Copying keep alive closure. Applied to referent objects that need
4256 // to be copied.
4257 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4258
4259 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4260
4261 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4262 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4263
4264 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4265 // So this must be true - but assert just in case someone decides to
4266 // change the worker ids.
4267 assert(worker_id < limit, "sanity");
4268 assert(!rp->discovery_is_atomic(), "check this code");
4269
4270 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4271 for (uint idx = worker_id; idx < limit; idx += stride) {
4272 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4273
4274 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4275 while (iter.has_next()) {
4276 // Since discovery is not atomic for the CM ref processor, we
4277 // can see some null referent objects.
4278 iter.load_ptrs(DEBUG_ONLY(true));
4279 oop ref = iter.obj();
4280
4281 // This will filter nulls.
4282 if (iter.is_referent_alive()) {
4283 iter.make_referent_alive();
4284 }
4285 iter.move_to_next();
4286 }
4287 }
4288
4289 // Drain the queue - which may cause stealing
4290 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4291 drain_queue.do_void();
4292 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4293 assert(pss->queue_is_empty(), "should be");
4294 }
4295 };
4296
4297 void G1CollectedHeap::process_weak_jni_handles() {
4298 double ref_proc_start = os::elapsedTime();
4299
4300 G1STWIsAliveClosure is_alive(this);
4301 G1KeepAliveClosure keep_alive(this);
4302 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4303
4304 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4305 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4306 }
4307
4308 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4309 // Any reference objects, in the collection set, that were 'discovered'
4310 // by the CM ref processor should have already been copied (either by
4311 // applying the external root copy closure to the discovered lists, or
4312 // by following an RSet entry).
4313 //
4314 // But some of the referents, that are in the collection set, that these
4315 // reference objects point to may not have been copied: the STW ref
4316 // processor would have seen that the reference object had already
4317 // been 'discovered' and would have skipped discovering the reference,
4318 // but would not have treated the reference object as a regular oop.
4319 // As a result the copy closure would not have been applied to the
4320 // referent object.
4321 //
4322 // We need to explicitly copy these referent objects - the references
4323 // will be processed at the end of remarking.
4324 //
4325 // We also need to do this copying before we process the reference
4326 // objects discovered by the STW ref processor in case one of these
4327 // referents points to another object which is also referenced by an
4328 // object discovered by the STW ref processor.
4329 double preserve_cm_referents_time = 0.0;
4330
4331 // To avoid spawning task when there is no work to do, check that
4332 // a concurrent cycle is active and that some references have been
4333 // discovered.
4334 if (concurrent_mark()->cmThread()->during_cycle() &&
4335 ref_processor_cm()->has_discovered_references()) {
4336 double preserve_cm_referents_start = os::elapsedTime();
4337 uint no_of_gc_workers = workers()->active_workers();
4338 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4339 per_thread_states,
4340 no_of_gc_workers,
4341 _task_queues);
4342 workers()->run_task(&keep_cm_referents);
4343 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4344 }
4345
4346 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4347 }
4348
4349 // Weak Reference processing during an evacuation pause (part 1).
4350 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4351 double ref_proc_start = os::elapsedTime();
4352
4353 ReferenceProcessor* rp = _ref_processor_stw;
4354 assert(rp->discovery_enabled(), "should have been enabled");
4355
4356 // Closure to test whether a referent is alive.
4357 G1STWIsAliveClosure is_alive(this);
4358
4359 // Even when parallel reference processing is enabled, the processing
4360 // of JNI refs is serial and performed serially by the current thread
4361 // rather than by a worker. The following PSS will be used for processing
4362 // JNI refs.
4363
4364 // Use only a single queue for this PSS.
4365 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4366 pss->set_ref_processor(NULL);
4367 assert(pss->queue_is_empty(), "pre-condition");
4368
4369 // Keep alive closure.
4370 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4371
4372 // Serial Complete GC closure
4373 G1STWDrainQueueClosure drain_queue(this, pss);
4374
4375 // Setup the soft refs policy...
4376 rp->setup_policy(false);
4377
4378 ReferenceProcessorStats stats;
4379 if (!rp->processing_is_mt()) {
4380 // Serial reference processing...
4381 stats = rp->process_discovered_references(&is_alive,
4382 &keep_alive,
4383 &drain_queue,
4384 NULL,
4385 _gc_timer_stw);
4386 } else {
4387 uint no_of_gc_workers = workers()->active_workers();
4388
4389 // Parallel reference processing
4390 assert(no_of_gc_workers <= rp->max_num_q(),
4391 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4392 no_of_gc_workers, rp->max_num_q());
4393
4394 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4395 stats = rp->process_discovered_references(&is_alive,
4396 &keep_alive,
4397 &drain_queue,
4398 &par_task_executor,
4399 _gc_timer_stw);
4400 }
4401
4402 _gc_tracer_stw->report_gc_reference_stats(stats);
4403
4404 // We have completed copying any necessary live referent objects.
4405 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4406
4407 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4408 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4409 }
4410
4411 // Weak Reference processing during an evacuation pause (part 2).
4412 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4413 double ref_enq_start = os::elapsedTime();
4414
4415 ReferenceProcessor* rp = _ref_processor_stw;
4416 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4417
4418 // Now enqueue any remaining on the discovered lists on to
4419 // the pending list.
4420 if (!rp->processing_is_mt()) {
4421 // Serial reference processing...
4422 rp->enqueue_discovered_references();
4423 } else {
4424 // Parallel reference enqueueing
4425
4426 uint n_workers = workers()->active_workers();
4427
4428 assert(n_workers <= rp->max_num_q(),
4429 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4430 n_workers, rp->max_num_q());
4431
4432 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4433 rp->enqueue_discovered_references(&par_task_executor);
4434 }
4435
4436 rp->verify_no_references_recorded();
4437 assert(!rp->discovery_enabled(), "should have been disabled");
4438
4439 // FIXME
4440 // CM's reference processing also cleans up the string and symbol tables.
4441 // Should we do that here also? We could, but it is a serial operation
4442 // and could significantly increase the pause time.
4443
4444 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4445 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4446 }
4447
4448 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4449 double merge_pss_time_start = os::elapsedTime();
4450 per_thread_states->flush();
4451 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4452 }
4453
4454 void G1CollectedHeap::pre_evacuate_collection_set() {
4455 _expand_heap_after_alloc_failure = true;
4456 _evacuation_failed = false;
4457
4458 // Disable the hot card cache.
4459 _hot_card_cache->reset_hot_cache_claimed_index();
4460 _hot_card_cache->set_use_cache(false);
4461
4462 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4463 _preserved_marks_set.assert_empty();
4464
4465 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4466
4467 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4468 if (collector_state()->during_initial_mark_pause()) {
4469 double start_clear_claimed_marks = os::elapsedTime();
4470
4471 ClassLoaderDataGraph::clear_claimed_marks();
4472
4473 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4474 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4475 }
4476 }
4477
4478 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4479 // Should G1EvacuationFailureALot be in effect for this GC?
4480 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4481
4482 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4483
4484 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4485
4486 double start_par_time_sec = os::elapsedTime();
4487 double end_par_time_sec;
4488
4489 {
4490 const uint n_workers = workers()->active_workers();
4491 G1RootProcessor root_processor(this, n_workers);
4492 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4493
4494 print_termination_stats_hdr();
4495
4496 workers()->run_task(&g1_par_task);
4497 end_par_time_sec = os::elapsedTime();
4498
4499 // Closing the inner scope will execute the destructor
4500 // for the G1RootProcessor object. We record the current
4501 // elapsed time before closing the scope so that time
4502 // taken for the destructor is NOT included in the
4503 // reported parallel time.
4504 }
4505
4506 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4507 phase_times->record_par_time(par_time_ms);
4508
4509 double code_root_fixup_time_ms =
4510 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4511 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4512 }
4513
4514 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4515 // Process any discovered reference objects - we have
4516 // to do this _before_ we retire the GC alloc regions
4517 // as we may have to copy some 'reachable' referent
4518 // objects (and their reachable sub-graphs) that were
4519 // not copied during the pause.
4520 if (g1_policy()->should_process_references()) {
4521 preserve_cm_referents(per_thread_states);
4522 process_discovered_references(per_thread_states);
4523 } else {
4524 ref_processor_stw()->verify_no_references_recorded();
4525 process_weak_jni_handles();
4526 }
4527
4528 if (G1StringDedup::is_enabled()) {
4529 double fixup_start = os::elapsedTime();
4530
4531 G1STWIsAliveClosure is_alive(this);
4532 G1KeepAliveClosure keep_alive(this);
4533 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4534
4535 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4536 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4537 }
4538
4539 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4540
4541 if (evacuation_failed()) {
4542 restore_after_evac_failure();
4543
4544 // Reset the G1EvacuationFailureALot counters and flags
4545 // Note: the values are reset only when an actual
4546 // evacuation failure occurs.
4547 NOT_PRODUCT(reset_evacuation_should_fail();)
4548 }
4549
4550 _preserved_marks_set.assert_empty();
4551
4552 // Enqueue any remaining references remaining on the STW
4553 // reference processor's discovered lists. We need to do
4554 // this after the card table is cleaned (and verified) as
4555 // the act of enqueueing entries on to the pending list
4556 // will log these updates (and dirty their associated
4557 // cards). We need these updates logged to update any
4558 // RSets.
4559 if (g1_policy()->should_process_references()) {
4560 enqueue_discovered_references(per_thread_states);
4561 } else {
4562 g1_policy()->phase_times()->record_ref_enq_time(0);
4563 }
4564
4565 _allocator->release_gc_alloc_regions(evacuation_info);
4566
4567 merge_per_thread_state_info(per_thread_states);
4568
4569 // Reset and re-enable the hot card cache.
4570 // Note the counts for the cards in the regions in the
4571 // collection set are reset when the collection set is freed.
4572 _hot_card_cache->reset_hot_cache();
4573 _hot_card_cache->set_use_cache(true);
4574
4575 purge_code_root_memory();
4576
4577 redirty_logged_cards();
4578 #if defined(COMPILER2) || INCLUDE_JVMCI
4579 double start = os::elapsedTime();
4580 DerivedPointerTable::update_pointers();
4581 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4582 #endif
4583 g1_policy()->print_age_table();
4584 }
4585
4586 void G1CollectedHeap::record_obj_copy_mem_stats() {
4587 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4588
4589 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4590 create_g1_evac_summary(&_old_evac_stats));
4591 }
4592
4593 void G1CollectedHeap::free_region(HeapRegion* hr,
4594 FreeRegionList* free_list,
4595 bool skip_remset,
4596 bool skip_hot_card_cache,
4597 bool locked) {
4598 assert(!hr->is_free(), "the region should not be free");
4599 assert(!hr->is_empty(), "the region should not be empty");
4600 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4601 assert(free_list != NULL, "pre-condition");
4602
4603 if (G1VerifyBitmaps) {
4604 MemRegion mr(hr->bottom(), hr->end());
4605 concurrent_mark()->clearRangePrevBitmap(mr);
4606 }
4607
4608 // Clear the card counts for this region.
4609 // Note: we only need to do this if the region is not young
4610 // (since we don't refine cards in young regions).
4611 if (!skip_hot_card_cache && !hr->is_young()) {
4612 _hot_card_cache->reset_card_counts(hr);
4613 }
4614 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4615 free_list->add_ordered(hr);
4616 }
4617
4618 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4619 FreeRegionList* free_list,
4620 bool skip_remset) {
4621 assert(hr->is_humongous(), "this is only for humongous regions");
4622 assert(free_list != NULL, "pre-condition");
4623 hr->clear_humongous();
4624 free_region(hr, free_list, skip_remset);
4625 }
4626
4627 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4628 const uint humongous_regions_removed) {
4629 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4630 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4631 _old_set.bulk_remove(old_regions_removed);
4632 _humongous_set.bulk_remove(humongous_regions_removed);
4633 }
4634
4635 }
4636
4637 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4638 assert(list != NULL, "list can't be null");
4639 if (!list->is_empty()) {
4640 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4641 _hrm.insert_list_into_free_list(list);
4642 }
4643 }
4644
4645 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4646 decrease_used(bytes);
4647 }
4648
4649 class G1ParScrubRemSetTask: public AbstractGangTask {
4650 protected:
4651 G1RemSet* _g1rs;
4652 HeapRegionClaimer _hrclaimer;
4653
4654 public:
4655 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4656 AbstractGangTask("G1 ScrubRS"),
4657 _g1rs(g1_rs),
4658 _hrclaimer(num_workers) {
4659 }
4660
4661 void work(uint worker_id) {
4662 _g1rs->scrub(worker_id, &_hrclaimer);
4663 }
4664 };
4665
4666 void G1CollectedHeap::scrub_rem_set() {
4667 uint num_workers = workers()->active_workers();
4668 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4669 workers()->run_task(&g1_par_scrub_rs_task);
4670 }
4671
4672 class G1FreeCollectionSetTask : public AbstractGangTask {
4673 private:
4674
4675 // Closure applied to all regions in the collection set to do work that needs to
4676 // be done serially in a single thread.
4677 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4678 private:
4679 EvacuationInfo* _evacuation_info;
4680 const size_t* _surviving_young_words;
4681
4682 // Bytes used in successfully evacuated regions before the evacuation.
4683 size_t _before_used_bytes;
4684 // Bytes used in unsucessfully evacuated regions before the evacuation
4685 size_t _after_used_bytes;
4686
4687 size_t _bytes_allocated_in_old_since_last_gc;
4688
4689 size_t _failure_used_words;
4690 size_t _failure_waste_words;
4691
4692 FreeRegionList _local_free_list;
4693 public:
4694 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4695 HeapRegionClosure(),
4696 _evacuation_info(evacuation_info),
4697 _surviving_young_words(surviving_young_words),
4698 _before_used_bytes(0),
4699 _after_used_bytes(0),
4700 _bytes_allocated_in_old_since_last_gc(0),
4701 _failure_used_words(0),
4702 _failure_waste_words(0),
4703 _local_free_list("Local Region List for CSet Freeing") {
4704 }
4705
4706 virtual bool doHeapRegion(HeapRegion* r) {
4707 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4708
4709 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4710 g1h->clear_in_cset(r);
4711
4712 if (r->is_young()) {
4713 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4714 "Young index %d is wrong for region %u of type %s with %u young regions",
4715 r->young_index_in_cset(),
4716 r->hrm_index(),
4717 r->get_type_str(),
4718 g1h->collection_set()->young_region_length());
4719 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4720 r->record_surv_words_in_group(words_survived);
4721 }
4722
4723 if (!r->evacuation_failed()) {
4724 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4725 _before_used_bytes += r->used();
4726 g1h->free_region(r,
4727 &_local_free_list,
4728 true, /* skip_remset */
4729 true, /* skip_hot_card_cache */
4730 true /* locked */);
4731 } else {
4732 r->uninstall_surv_rate_group();
4733 r->set_young_index_in_cset(-1);
4734 r->set_evacuation_failed(false);
4735 // When moving a young gen region to old gen, we "allocate" that whole region
4736 // there. This is in addition to any already evacuated objects. Notify the
4737 // policy about that.
4738 // Old gen regions do not cause an additional allocation: both the objects
4739 // still in the region and the ones already moved are accounted for elsewhere.
4740 if (r->is_young()) {
4741 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4742 }
4743 // The region is now considered to be old.
4744 r->set_old();
4745 // Do some allocation statistics accounting. Regions that failed evacuation
4746 // are always made old, so there is no need to update anything in the young
4747 // gen statistics, but we need to update old gen statistics.
4748 size_t used_words = r->marked_bytes() / HeapWordSize;
4749
4750 _failure_used_words += used_words;
4751 _failure_waste_words += HeapRegion::GrainWords - used_words;
4752
4753 g1h->old_set_add(r);
4754 _after_used_bytes += r->used();
4755 }
4756 return false;
4757 }
4758
4759 void complete_work() {
4760 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4761
4762 _evacuation_info->set_regions_freed(_local_free_list.length());
4763 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4764
4765 g1h->prepend_to_freelist(&_local_free_list);
4766 g1h->decrement_summary_bytes(_before_used_bytes);
4767
4768 G1Policy* policy = g1h->g1_policy();
4769 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4770
4771 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4772 }
4773 };
4774
4775 G1CollectionSet* _collection_set;
4776 G1SerialFreeCollectionSetClosure _cl;
4777 const size_t* _surviving_young_words;
4778
4779 size_t _rs_lengths;
4780
4781 volatile jint _serial_work_claim;
4782
4783 struct WorkItem {
4784 uint region_idx;
4785 bool is_young;
4786 bool evacuation_failed;
4787
4788 WorkItem(HeapRegion* r) {
4789 region_idx = r->hrm_index();
4790 is_young = r->is_young();
4791 evacuation_failed = r->evacuation_failed();
4792 }
4793 };
4794
4795 volatile size_t _parallel_work_claim;
4796 size_t _num_work_items;
4797 WorkItem* _work_items;
4798
4799 void do_serial_work() {
4800 // Need to grab the lock to be allowed to modify the old region list.
4801 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4802 _collection_set->iterate(&_cl);
4803 }
4804
4805 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4806 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4807
4808 HeapRegion* r = g1h->region_at(region_idx);
4809 assert(!g1h->is_on_master_free_list(r), "sanity");
4810
4811 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4812
4813 if (!is_young) {
4814 g1h->_hot_card_cache->reset_card_counts(r);
4815 }
4816
4817 if (!evacuation_failed) {
4818 r->rem_set()->clear_locked();
4819 }
4820 }
4821
4822 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4823 private:
4824 size_t _cur_idx;
4825 WorkItem* _work_items;
4826 public:
4827 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4828
4829 virtual bool doHeapRegion(HeapRegion* r) {
4830 _work_items[_cur_idx++] = WorkItem(r);
4831 return false;
4832 }
4833 };
4834
4835 void prepare_work() {
4836 G1PrepareFreeCollectionSetClosure cl(_work_items);
4837 _collection_set->iterate(&cl);
4838 }
4839
4840 void complete_work() {
4841 _cl.complete_work();
4842
4843 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4844 policy->record_max_rs_lengths(_rs_lengths);
4845 policy->cset_regions_freed();
4846 }
4847 public:
4848 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4849 AbstractGangTask("G1 Free Collection Set"),
4850 _cl(evacuation_info, surviving_young_words),
4851 _collection_set(collection_set),
4852 _surviving_young_words(surviving_young_words),
4853 _serial_work_claim(0),
4854 _rs_lengths(0),
4855 _parallel_work_claim(0),
4856 _num_work_items(collection_set->region_length()),
4857 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4858 prepare_work();
4859 }
4860
4861 ~G1FreeCollectionSetTask() {
4862 complete_work();
4863 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4864 }
4865
4866 // Chunk size for work distribution. The chosen value has been determined experimentally
4867 // to be a good tradeoff between overhead and achievable parallelism.
4868 static uint chunk_size() { return 32; }
4869
4870 virtual void work(uint worker_id) {
4871 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4872
4873 // Claim serial work.
4874 if (_serial_work_claim == 0) {
4875 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4876 if (value == 0) {
4877 double serial_time = os::elapsedTime();
4878 do_serial_work();
4879 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4880 }
4881 }
4882
4883 // Start parallel work.
4884 double young_time = 0.0;
4885 bool has_young_time = false;
4886 double non_young_time = 0.0;
4887 bool has_non_young_time = false;
4888
4889 while (true) {
4890 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4891 size_t cur = end - chunk_size();
4892
4893 if (cur >= _num_work_items) {
4894 break;
4895 }
4896
4897 double start_time = os::elapsedTime();
4898
4899 end = MIN2(end, _num_work_items);
4900
4901 for (; cur < end; cur++) {
4902 bool is_young = _work_items[cur].is_young;
4903
4904 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4905
4906 double end_time = os::elapsedTime();
4907 double time_taken = end_time - start_time;
4908 if (is_young) {
4909 young_time += time_taken;
4910 has_young_time = true;
4911 } else {
4912 non_young_time += time_taken;
4913 has_non_young_time = true;
4914 }
4915 start_time = end_time;
4916 }
4917 }
4918
4919 if (has_young_time) {
4920 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4921 }
4922 if (has_non_young_time) {
4923 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4924 }
4925 }
4926 };
4927
4928 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4929 _eden.clear();
4930
4931 double free_cset_start_time = os::elapsedTime();
4932
4933 {
4934 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4935 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4936
4937 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4938
4939 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4940 cl.name(),
4941 num_workers,
4942 _collection_set.region_length());
4943 workers()->run_task(&cl, num_workers);
4944 }
4945 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4946
4947 collection_set->clear();
4948 }
4949
4950 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4951 private:
4952 FreeRegionList* _free_region_list;
4953 HeapRegionSet* _proxy_set;
4954 uint _humongous_objects_reclaimed;
4955 uint _humongous_regions_reclaimed;
4956 size_t _freed_bytes;
4957 public:
4958
4959 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4960 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4961 }
4962
4963 virtual bool doHeapRegion(HeapRegion* r) {
4964 if (!r->is_starts_humongous()) {
4965 return false;
4966 }
4967
4968 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4969
4970 oop obj = (oop)r->bottom();
4971 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4972
4973 // The following checks whether the humongous object is live are sufficient.
4974 // The main additional check (in addition to having a reference from the roots
4975 // or the young gen) is whether the humongous object has a remembered set entry.
4976 //
4977 // A humongous object cannot be live if there is no remembered set for it
4978 // because:
4979 // - there can be no references from within humongous starts regions referencing
4980 // the object because we never allocate other objects into them.
4981 // (I.e. there are no intra-region references that may be missed by the
4982 // remembered set)
4983 // - as soon there is a remembered set entry to the humongous starts region
4984 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4985 // until the end of a concurrent mark.
4986 //
4987 // It is not required to check whether the object has been found dead by marking
4988 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4989 // all objects allocated during that time are considered live.
4990 // SATB marking is even more conservative than the remembered set.
4991 // So if at this point in the collection there is no remembered set entry,
4992 // nobody has a reference to it.
4993 // At the start of collection we flush all refinement logs, and remembered sets
4994 // are completely up-to-date wrt to references to the humongous object.
4995 //
4996 // Other implementation considerations:
4997 // - never consider object arrays at this time because they would pose
4998 // considerable effort for cleaning up the the remembered sets. This is
4999 // required because stale remembered sets might reference locations that
5000 // are currently allocated into.
5001 uint region_idx = r->hrm_index();
5002 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5003 !r->rem_set()->is_empty()) {
5004 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",
5005 region_idx,
5006 (size_t)obj->size() * HeapWordSize,
5007 p2i(r->bottom()),
5008 r->rem_set()->occupied(),
5009 r->rem_set()->strong_code_roots_list_length(),
5010 next_bitmap->isMarked(r->bottom()),
5011 g1h->is_humongous_reclaim_candidate(region_idx),
5012 obj->is_typeArray()
5013 );
5014 return false;
5015 }
5016
5017 guarantee(obj->is_typeArray(),
5018 "Only eagerly reclaiming type arrays is supported, but the object "
5019 PTR_FORMAT " is not.", p2i(r->bottom()));
5020
5021 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",
5022 region_idx,
5023 (size_t)obj->size() * HeapWordSize,
5024 p2i(r->bottom()),
5025 r->rem_set()->occupied(),
5026 r->rem_set()->strong_code_roots_list_length(),
5027 next_bitmap->isMarked(r->bottom()),
5028 g1h->is_humongous_reclaim_candidate(region_idx),
5029 obj->is_typeArray()
5030 );
5031
5032 // Need to clear mark bit of the humongous object if already set.
5033 if (next_bitmap->isMarked(r->bottom())) {
5034 next_bitmap->clear(r->bottom());
5035 }
5036 _humongous_objects_reclaimed++;
5037 do {
5038 HeapRegion* next = g1h->next_region_in_humongous(r);
5039 _freed_bytes += r->used();
5040 r->set_containing_set(NULL);
5041 _humongous_regions_reclaimed++;
5042 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
5043 r = next;
5044 } while (r != NULL);
5045
5046 return false;
5047 }
5048
5049 uint humongous_objects_reclaimed() {
5050 return _humongous_objects_reclaimed;
5051 }
5052
5053 uint humongous_regions_reclaimed() {
5054 return _humongous_regions_reclaimed;
5055 }
5056
5057 size_t bytes_freed() const {
5058 return _freed_bytes;
5059 }
5060 };
5061
5062 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5063 assert_at_safepoint(true);
5064
5065 if (!G1EagerReclaimHumongousObjects ||
5066 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5067 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5068 return;
5069 }
5070
5071 double start_time = os::elapsedTime();
5072
5073 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5074
5075 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5076 heap_region_iterate(&cl);
5077
5078 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
5079
5080 G1HRPrinter* hrp = hr_printer();
5081 if (hrp->is_active()) {
5082 FreeRegionListIterator iter(&local_cleanup_list);
5083 while (iter.more_available()) {
5084 HeapRegion* hr = iter.get_next();
5085 hrp->cleanup(hr);
5086 }
5087 }
5088
5089 prepend_to_freelist(&local_cleanup_list);
5090 decrement_summary_bytes(cl.bytes_freed());
5091
5092 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5093 cl.humongous_objects_reclaimed());
5094 }
5095
5096 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5097 public:
5098 virtual bool doHeapRegion(HeapRegion* r) {
5099 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5100 G1CollectedHeap::heap()->clear_in_cset(r);
5101 r->set_young_index_in_cset(-1);
5102 return false;
5103 }
5104 };
5105
5106 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5107 G1AbandonCollectionSetClosure cl;
5108 collection_set->iterate(&cl);
5109
5110 collection_set->clear();
5111 collection_set->stop_incremental_building();
5112 }
5113
5114 void G1CollectedHeap::set_free_regions_coming() {
5115 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5116
5117 assert(!free_regions_coming(), "pre-condition");
5118 _free_regions_coming = true;
5119 }
5120
5121 void G1CollectedHeap::reset_free_regions_coming() {
5122 assert(free_regions_coming(), "pre-condition");
5123
5124 {
5125 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5126 _free_regions_coming = false;
5127 SecondaryFreeList_lock->notify_all();
5128 }
5129
5130 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5131 }
5132
5133 void G1CollectedHeap::wait_while_free_regions_coming() {
5134 // Most of the time we won't have to wait, so let's do a quick test
5135 // first before we take the lock.
5136 if (!free_regions_coming()) {
5137 return;
5138 }
5139
5140 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5141
5142 {
5143 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5144 while (free_regions_coming()) {
5145 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5146 }
5147 }
5148
5149 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5150 }
5151
5152 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5153 return _allocator->is_retained_old_region(hr);
5154 }
5155
5156 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5157 _eden.add(hr);
5158 _g1_policy->set_region_eden(hr);
5159 }
5160
5161 #ifdef ASSERT
5162
5163 class NoYoungRegionsClosure: public HeapRegionClosure {
5164 private:
5165 bool _success;
5166 public:
5167 NoYoungRegionsClosure() : _success(true) { }
5168 bool doHeapRegion(HeapRegion* r) {
5169 if (r->is_young()) {
5170 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5171 p2i(r->bottom()), p2i(r->end()));
5172 _success = false;
5173 }
5174 return false;
5175 }
5176 bool success() { return _success; }
5177 };
5178
5179 bool G1CollectedHeap::check_young_list_empty() {
5180 bool ret = (young_regions_count() == 0);
5181
5182 NoYoungRegionsClosure closure;
5183 heap_region_iterate(&closure);
5184 ret = ret && closure.success();
5185
5186 return ret;
5187 }
5188
5189 #endif // ASSERT
5190
5191 class TearDownRegionSetsClosure : public HeapRegionClosure {
5192 private:
5193 HeapRegionSet *_old_set;
5194
5195 public:
5196 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5197
5198 bool doHeapRegion(HeapRegion* r) {
5199 if (r->is_old()) {
5200 _old_set->remove(r);
5201 } else if(r->is_young()) {
5202 r->uninstall_surv_rate_group();
5203 } else {
5204 // We ignore free regions, we'll empty the free list afterwards.
5205 // We ignore humongous regions, we're not tearing down the
5206 // humongous regions set.
5207 assert(r->is_free() || r->is_humongous(),
5208 "it cannot be another type");
5209 }
5210 return false;
5211 }
5212
5213 ~TearDownRegionSetsClosure() {
5214 assert(_old_set->is_empty(), "post-condition");
5215 }
5216 };
5217
5218 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5219 assert_at_safepoint(true /* should_be_vm_thread */);
5220
5221 if (!free_list_only) {
5222 TearDownRegionSetsClosure cl(&_old_set);
5223 heap_region_iterate(&cl);
5224
5225 // Note that emptying the _young_list is postponed and instead done as
5226 // the first step when rebuilding the regions sets again. The reason for
5227 // this is that during a full GC string deduplication needs to know if
5228 // a collected region was young or old when the full GC was initiated.
5229 }
5230 _hrm.remove_all_free_regions();
5231 }
5232
5233 void G1CollectedHeap::increase_used(size_t bytes) {
5234 _summary_bytes_used += bytes;
5235 }
5236
5237 void G1CollectedHeap::decrease_used(size_t bytes) {
5238 assert(_summary_bytes_used >= bytes,
5239 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5240 _summary_bytes_used, bytes);
5241 _summary_bytes_used -= bytes;
5242 }
5243
5244 void G1CollectedHeap::set_used(size_t bytes) {
5245 _summary_bytes_used = bytes;
5246 }
5247
5248 class RebuildRegionSetsClosure : public HeapRegionClosure {
5249 private:
5250 bool _free_list_only;
5251 HeapRegionSet* _old_set;
5252 HeapRegionManager* _hrm;
5253 size_t _total_used;
5254
5255 public:
5256 RebuildRegionSetsClosure(bool free_list_only,
5257 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5258 _free_list_only(free_list_only),
5259 _old_set(old_set), _hrm(hrm), _total_used(0) {
5260 assert(_hrm->num_free_regions() == 0, "pre-condition");
5261 if (!free_list_only) {
5262 assert(_old_set->is_empty(), "pre-condition");
5263 }
5264 }
5265
5266 bool doHeapRegion(HeapRegion* r) {
5267 if (r->is_empty()) {
5268 // Add free regions to the free list
5269 r->set_free();
5270 r->set_allocation_context(AllocationContext::system());
5271 _hrm->insert_into_free_list(r);
5272 } else if (!_free_list_only) {
5273
5274 if (r->is_humongous()) {
5275 // We ignore humongous regions. We left the humongous set unchanged.
5276 } else {
5277 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5278 // We now consider all regions old, so register as such. Leave
5279 // archive regions set that way, however, while still adding
5280 // them to the old set.
5281 if (!r->is_archive()) {
5282 r->set_old();
5283 }
5284 _old_set->add(r);
5285 }
5286 _total_used += r->used();
5287 }
5288
5289 return false;
5290 }
5291
5292 size_t total_used() {
5293 return _total_used;
5294 }
5295 };
5296
5297 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5298 assert_at_safepoint(true /* should_be_vm_thread */);
5299
5300 if (!free_list_only) {
5301 _eden.clear();
5302 _survivor.clear();
5303 }
5304
5305 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5306 heap_region_iterate(&cl);
5307
5308 if (!free_list_only) {
5309 set_used(cl.total_used());
5310 if (_archive_allocator != NULL) {
5311 _archive_allocator->clear_used();
5312 }
5313 }
5314 assert(used_unlocked() == recalculate_used(),
5315 "inconsistent used_unlocked(), "
5316 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5317 used_unlocked(), recalculate_used());
5318 }
5319
5320 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5321 _refine_cte_cl->set_concurrent(concurrent);
5322 }
5323
5324 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5325 HeapRegion* hr = heap_region_containing(p);
5326 return hr->is_in(p);
5327 }
5328
5329 // Methods for the mutator alloc region
5330
5331 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5332 bool force) {
5333 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5334 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5335 if (force || should_allocate) {
5336 HeapRegion* new_alloc_region = new_region(word_size,
5337 false /* is_old */,
5338 false /* do_expand */);
5339 if (new_alloc_region != NULL) {
5340 set_region_short_lived_locked(new_alloc_region);
5341 _hr_printer.alloc(new_alloc_region, !should_allocate);
5342 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5343 return new_alloc_region;
5344 }
5345 }
5346 return NULL;
5347 }
5348
5349 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5350 size_t allocated_bytes) {
5351 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5352 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5353
5354 collection_set()->add_eden_region(alloc_region);
5355 increase_used(allocated_bytes);
5356 _hr_printer.retire(alloc_region);
5357 // We update the eden sizes here, when the region is retired,
5358 // instead of when it's allocated, since this is the point that its
5359 // used space has been recored in _summary_bytes_used.
5360 g1mm()->update_eden_size();
5361 }
5362
5363 // Methods for the GC alloc regions
5364
5365 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5366 if (dest.is_old()) {
5367 return true;
5368 } else {
5369 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5370 }
5371 }
5372
5373 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5374 assert(FreeList_lock->owned_by_self(), "pre-condition");
5375
5376 if (!has_more_regions(dest)) {
5377 return NULL;
5378 }
5379
5380 const bool is_survivor = dest.is_young();
5381
5382 HeapRegion* new_alloc_region = new_region(word_size,
5383 !is_survivor,
5384 true /* do_expand */);
5385 if (new_alloc_region != NULL) {
5386 // We really only need to do this for old regions given that we
5387 // should never scan survivors. But it doesn't hurt to do it
5388 // for survivors too.
5389 new_alloc_region->record_timestamp();
5390 if (is_survivor) {
5391 new_alloc_region->set_survivor();
5392 _survivor.add(new_alloc_region);
5393 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5394 } else {
5395 new_alloc_region->set_old();
5396 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5397 }
5398 _hr_printer.alloc(new_alloc_region);
5399 bool during_im = collector_state()->during_initial_mark_pause();
5400 new_alloc_region->note_start_of_copying(during_im);
5401 return new_alloc_region;
5402 }
5403 return NULL;
5404 }
5405
5406 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5407 size_t allocated_bytes,
5408 InCSetState dest) {
5409 bool during_im = collector_state()->during_initial_mark_pause();
5410 alloc_region->note_end_of_copying(during_im);
5411 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5412 if (dest.is_old()) {
5413 _old_set.add(alloc_region);
5414 }
5415 _hr_printer.retire(alloc_region);
5416 }
5417
5418 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5419 bool expanded = false;
5420 uint index = _hrm.find_highest_free(&expanded);
5421
5422 if (index != G1_NO_HRM_INDEX) {
5423 if (expanded) {
5424 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5425 HeapRegion::GrainWords * HeapWordSize);
5426 }
5427 _hrm.allocate_free_regions_starting_at(index, 1);
5428 return region_at(index);
5429 }
5430 return NULL;
5431 }
5432
5433 // Optimized nmethod scanning
5434
5435 class RegisterNMethodOopClosure: public OopClosure {
5436 G1CollectedHeap* _g1h;
5437 nmethod* _nm;
5438
5439 template <class T> void do_oop_work(T* p) {
5440 T heap_oop = oopDesc::load_heap_oop(p);
5441 if (!oopDesc::is_null(heap_oop)) {
5442 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5443 HeapRegion* hr = _g1h->heap_region_containing(obj);
5444 assert(!hr->is_continues_humongous(),
5445 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5446 " starting at " HR_FORMAT,
5447 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5448
5449 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5450 hr->add_strong_code_root_locked(_nm);
5451 }
5452 }
5453
5454 public:
5455 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5456 _g1h(g1h), _nm(nm) {}
5457
5458 void do_oop(oop* p) { do_oop_work(p); }
5459 void do_oop(narrowOop* p) { do_oop_work(p); }
5460 };
5461
5462 class UnregisterNMethodOopClosure: public OopClosure {
5463 G1CollectedHeap* _g1h;
5464 nmethod* _nm;
5465
5466 template <class T> void do_oop_work(T* p) {
5467 T heap_oop = oopDesc::load_heap_oop(p);
5468 if (!oopDesc::is_null(heap_oop)) {
5469 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5470 HeapRegion* hr = _g1h->heap_region_containing(obj);
5471 assert(!hr->is_continues_humongous(),
5472 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5473 " starting at " HR_FORMAT,
5474 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5475
5476 hr->remove_strong_code_root(_nm);
5477 }
5478 }
5479
5480 public:
5481 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5482 _g1h(g1h), _nm(nm) {}
5483
5484 void do_oop(oop* p) { do_oop_work(p); }
5485 void do_oop(narrowOop* p) { do_oop_work(p); }
5486 };
5487
5488 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5489 CollectedHeap::register_nmethod(nm);
5490
5491 guarantee(nm != NULL, "sanity");
5492 RegisterNMethodOopClosure reg_cl(this, nm);
5493 nm->oops_do(®_cl);
5494 }
5495
5496 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5497 CollectedHeap::unregister_nmethod(nm);
5498
5499 guarantee(nm != NULL, "sanity");
5500 UnregisterNMethodOopClosure reg_cl(this, nm);
5501 nm->oops_do(®_cl, true);
5502 }
5503
5504 void G1CollectedHeap::purge_code_root_memory() {
5505 double purge_start = os::elapsedTime();
5506 G1CodeRootSet::purge();
5507 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5508 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5509 }
5510
5511 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5512 G1CollectedHeap* _g1h;
5513
5514 public:
5515 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5516 _g1h(g1h) {}
5517
5518 void do_code_blob(CodeBlob* cb) {
5519 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5520 if (nm == NULL) {
5521 return;
5522 }
5523
5524 if (ScavengeRootsInCode) {
5525 _g1h->register_nmethod(nm);
5526 }
5527 }
5528 };
5529
5530 void G1CollectedHeap::rebuild_strong_code_roots() {
5531 RebuildStrongCodeRootClosure blob_cl(this);
5532 CodeCache::blobs_do(&blob_cl);
5533 }