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/g1FullGCScope.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.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/g1SerialFullCollector.hpp"
55 #include "gc/g1/g1StringDedup.hpp"
56 #include "gc/g1/g1YCTypes.hpp"
57 #include "gc/g1/heapRegion.inline.hpp"
58 #include "gc/g1/heapRegionRemSet.hpp"
59 #include "gc/g1/heapRegionSet.inline.hpp"
60 #include "gc/g1/suspendibleThreadSet.hpp"
61 #include "gc/g1/vm_operations_g1.hpp"
62 #include "gc/shared/gcHeapSummary.hpp"
63 #include "gc/shared/gcId.hpp"
64 #include "gc/shared/gcLocker.inline.hpp"
65 #include "gc/shared/gcTimer.hpp"
66 #include "gc/shared/gcTrace.hpp"
67 #include "gc/shared/gcTraceTime.inline.hpp"
68 #include "gc/shared/generationSpec.hpp"
69 #include "gc/shared/isGCActiveMark.hpp"
70 #include "gc/shared/preservedMarks.inline.hpp"
71 #include "gc/shared/referenceProcessor.inline.hpp"
72 #include "gc/shared/taskqueue.inline.hpp"
73 #include "logging/log.hpp"
74 #include "memory/allocation.hpp"
75 #include "memory/iterator.hpp"
76 #include "memory/resourceArea.hpp"
77 #include "oops/oop.inline.hpp"
78 #include "prims/resolvedMethodTable.hpp"
79 #include "runtime/atomic.hpp"
80 #include "runtime/init.hpp"
81 #include "runtime/orderAccess.inline.hpp"
82 #include "runtime/vmThread.hpp"
83 #include "utilities/align.hpp"
84 #include "utilities/globalDefinitions.hpp"
85 #include "utilities/stack.inline.hpp"
86
87 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
88
89 // INVARIANTS/NOTES
90 //
91 // All allocation activity covered by the G1CollectedHeap interface is
92 // serialized by acquiring the HeapLock. This happens in mem_allocate
93 // and allocate_new_tlab, which are the "entry" points to the
94 // allocation code from the rest of the JVM. (Note that this does not
95 // apply to TLAB allocation, which is not part of this interface: it
96 // is done by clients of this interface.)
97
98 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
99 private:
100 size_t _num_dirtied;
101 G1CollectedHeap* _g1h;
102 G1SATBCardTableLoggingModRefBS* _g1_bs;
103
104 HeapRegion* region_for_card(jbyte* card_ptr) const {
105 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
106 }
107
108 bool will_become_free(HeapRegion* hr) const {
109 // A region will be freed by free_collection_set if the region is in the
110 // collection set and has not had an evacuation failure.
111 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
112 }
113
114 public:
115 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
116 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
117
118 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
119 HeapRegion* hr = region_for_card(card_ptr);
120
121 // Should only dirty cards in regions that won't be freed.
122 if (!will_become_free(hr)) {
123 *card_ptr = CardTableModRefBS::dirty_card_val();
124 _num_dirtied++;
125 }
126
127 return true;
128 }
129
130 size_t num_dirtied() const { return _num_dirtied; }
131 };
132
133
134 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
135 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
136 }
137
138 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
139 // The from card cache is not the memory that is actually committed. So we cannot
140 // take advantage of the zero_filled parameter.
141 reset_from_card_cache(start_idx, num_regions);
142 }
143
144 // Returns true if the reference points to an object that
145 // can move in an incremental collection.
146 bool G1CollectedHeap::is_scavengable(const void* p) {
147 HeapRegion* hr = heap_region_containing(p);
148 return !hr->is_pinned();
149 }
150
151 // Private methods.
152
153 HeapRegion*
154 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
155 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
156 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
157 if (!_secondary_free_list.is_empty()) {
158 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
159 "secondary_free_list has %u entries",
160 _secondary_free_list.length());
161 // It looks as if there are free regions available on the
162 // secondary_free_list. Let's move them to the free_list and try
163 // again to allocate from it.
164 append_secondary_free_list();
165
166 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
167 "empty we should have moved at least one entry to the free_list");
168 HeapRegion* res = _hrm.allocate_free_region(is_old);
169 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
170 "allocated " HR_FORMAT " from secondary_free_list",
171 HR_FORMAT_PARAMS(res));
172 return res;
173 }
174
175 // Wait here until we get notified either when (a) there are no
176 // more free regions coming or (b) some regions have been moved on
177 // the secondary_free_list.
178 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
179 }
180
181 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
182 "could not allocate from secondary_free_list");
183 return NULL;
184 }
185
186 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
187 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
188 "the only time we use this to allocate a humongous region is "
189 "when we are allocating a single humongous region");
190
191 HeapRegion* res;
192 if (G1StressConcRegionFreeing) {
193 if (!_secondary_free_list.is_empty()) {
194 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
195 "forced to look at the secondary_free_list");
196 res = new_region_try_secondary_free_list(is_old);
197 if (res != NULL) {
198 return res;
199 }
200 }
201 }
202
203 res = _hrm.allocate_free_region(is_old);
204
205 if (res == NULL) {
206 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
207 "res == NULL, trying the secondary_free_list");
208 res = new_region_try_secondary_free_list(is_old);
209 }
210 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
211 // Currently, only attempts to allocate GC alloc regions set
212 // do_expand to true. So, we should only reach here during a
213 // safepoint. If this assumption changes we might have to
214 // reconsider the use of _expand_heap_after_alloc_failure.
215 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
216
217 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
218 word_size * HeapWordSize);
219
220 if (expand(word_size * HeapWordSize)) {
221 // Given that expand() succeeded in expanding the heap, and we
222 // always expand the heap by an amount aligned to the heap
223 // region size, the free list should in theory not be empty.
224 // In either case allocate_free_region() will check for NULL.
225 res = _hrm.allocate_free_region(is_old);
226 } else {
227 _expand_heap_after_alloc_failure = false;
228 }
229 }
230 return res;
231 }
232
233 HeapWord*
234 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
235 uint num_regions,
236 size_t word_size,
237 AllocationContext_t context) {
238 assert(first != G1_NO_HRM_INDEX, "pre-condition");
239 assert(is_humongous(word_size), "word_size should be humongous");
240 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
241
242 // Index of last region in the series.
243 uint last = first + num_regions - 1;
244
245 // We need to initialize the region(s) we just discovered. This is
246 // a bit tricky given that it can happen concurrently with
247 // refinement threads refining cards on these regions and
248 // potentially wanting to refine the BOT as they are scanning
249 // those cards (this can happen shortly after a cleanup; see CR
250 // 6991377). So we have to set up the region(s) carefully and in
251 // a specific order.
252
253 // The word size sum of all the regions we will allocate.
254 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
255 assert(word_size <= word_size_sum, "sanity");
256
257 // This will be the "starts humongous" region.
258 HeapRegion* first_hr = region_at(first);
259 // The header of the new object will be placed at the bottom of
260 // the first region.
261 HeapWord* new_obj = first_hr->bottom();
262 // This will be the new top of the new object.
263 HeapWord* obj_top = new_obj + word_size;
264
265 // First, we need to zero the header of the space that we will be
266 // allocating. When we update top further down, some refinement
267 // threads might try to scan the region. By zeroing the header we
268 // ensure that any thread that will try to scan the region will
269 // come across the zero klass word and bail out.
270 //
271 // NOTE: It would not have been correct to have used
272 // CollectedHeap::fill_with_object() and make the space look like
273 // an int array. The thread that is doing the allocation will
274 // later update the object header to a potentially different array
275 // type and, for a very short period of time, the klass and length
276 // fields will be inconsistent. This could cause a refinement
277 // thread to calculate the object size incorrectly.
278 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
279
280 // Next, pad out the unused tail of the last region with filler
281 // objects, for improved usage accounting.
282 // How many words we use for filler objects.
283 size_t word_fill_size = word_size_sum - word_size;
284
285 // How many words memory we "waste" which cannot hold a filler object.
286 size_t words_not_fillable = 0;
287
288 if (word_fill_size >= min_fill_size()) {
289 fill_with_objects(obj_top, word_fill_size);
290 } else if (word_fill_size > 0) {
291 // We have space to fill, but we cannot fit an object there.
292 words_not_fillable = word_fill_size;
293 word_fill_size = 0;
294 }
295
296 // We will set up the first region as "starts humongous". This
297 // will also update the BOT covering all the regions to reflect
298 // that there is a single object that starts at the bottom of the
299 // first region.
300 first_hr->set_starts_humongous(obj_top, word_fill_size);
301 first_hr->set_allocation_context(context);
302 // Then, if there are any, we will set up the "continues
303 // humongous" regions.
304 HeapRegion* hr = NULL;
305 for (uint i = first + 1; i <= last; ++i) {
306 hr = region_at(i);
307 hr->set_continues_humongous(first_hr);
308 hr->set_allocation_context(context);
309 }
310
311 // Up to this point no concurrent thread would have been able to
312 // do any scanning on any region in this series. All the top
313 // fields still point to bottom, so the intersection between
314 // [bottom,top] and [card_start,card_end] will be empty. Before we
315 // update the top fields, we'll do a storestore to make sure that
316 // no thread sees the update to top before the zeroing of the
317 // object header and the BOT initialization.
318 OrderAccess::storestore();
319
320 // Now, we will update the top fields of the "continues humongous"
321 // regions except the last one.
322 for (uint i = first; i < last; ++i) {
323 hr = region_at(i);
324 hr->set_top(hr->end());
325 }
326
327 hr = region_at(last);
328 // If we cannot fit a filler object, we must set top to the end
329 // of the humongous object, otherwise we cannot iterate the heap
330 // and the BOT will not be complete.
331 hr->set_top(hr->end() - words_not_fillable);
332
333 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
334 "obj_top should be in last region");
335
336 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
337
338 assert(words_not_fillable == 0 ||
339 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
340 "Miscalculation in humongous allocation");
341
342 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
343
344 for (uint i = first; i <= last; ++i) {
345 hr = region_at(i);
346 _humongous_set.add(hr);
347 _hr_printer.alloc(hr);
348 }
349
350 return new_obj;
351 }
352
353 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
354 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
355 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
356 }
357
358 // If could fit into free regions w/o expansion, try.
359 // Otherwise, if can expand, do so.
360 // Otherwise, if using ex regions might help, try with ex given back.
361 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
362 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
363
364 _verifier->verify_region_sets_optional();
365
366 uint first = G1_NO_HRM_INDEX;
367 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
368
369 if (obj_regions == 1) {
370 // Only one region to allocate, try to use a fast path by directly allocating
371 // from the free lists. Do not try to expand here, we will potentially do that
372 // later.
373 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
374 if (hr != NULL) {
375 first = hr->hrm_index();
376 }
377 } else {
378 // We can't allocate humongous regions spanning more than one region while
379 // cleanupComplete() is running, since some of the regions we find to be
380 // empty might not yet be added to the free list. It is not straightforward
381 // to know in which list they are on so that we can remove them. We only
382 // need to do this if we need to allocate more than one region to satisfy the
383 // current humongous allocation request. If we are only allocating one region
384 // we use the one-region region allocation code (see above), that already
385 // potentially waits for regions from the secondary free list.
386 wait_while_free_regions_coming();
387 append_secondary_free_list_if_not_empty_with_lock();
388
389 // Policy: Try only empty regions (i.e. already committed first). Maybe we
390 // are lucky enough to find some.
391 first = _hrm.find_contiguous_only_empty(obj_regions);
392 if (first != G1_NO_HRM_INDEX) {
393 _hrm.allocate_free_regions_starting_at(first, obj_regions);
394 }
395 }
396
397 if (first == G1_NO_HRM_INDEX) {
398 // Policy: We could not find enough regions for the humongous object in the
399 // free list. Look through the heap to find a mix of free and uncommitted regions.
400 // If so, try expansion.
401 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
402 if (first != G1_NO_HRM_INDEX) {
403 // We found something. Make sure these regions are committed, i.e. expand
404 // the heap. Alternatively we could do a defragmentation GC.
405 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
406 word_size * HeapWordSize);
407
408 _hrm.expand_at(first, obj_regions, workers());
409 g1_policy()->record_new_heap_size(num_regions());
410
411 #ifdef ASSERT
412 for (uint i = first; i < first + obj_regions; ++i) {
413 HeapRegion* hr = region_at(i);
414 assert(hr->is_free(), "sanity");
415 assert(hr->is_empty(), "sanity");
416 assert(is_on_master_free_list(hr), "sanity");
417 }
418 #endif
419 _hrm.allocate_free_regions_starting_at(first, obj_regions);
420 } else {
421 // Policy: Potentially trigger a defragmentation GC.
422 }
423 }
424
425 HeapWord* result = NULL;
426 if (first != G1_NO_HRM_INDEX) {
427 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
428 word_size, context);
429 assert(result != NULL, "it should always return a valid result");
430
431 // A successful humongous object allocation changes the used space
432 // information of the old generation so we need to recalculate the
433 // sizes and update the jstat counters here.
434 g1mm()->update_sizes();
435 }
436
437 _verifier->verify_region_sets_optional();
438
439 return result;
440 }
441
442 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
443 assert_heap_not_locked_and_not_at_safepoint();
444 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
445
446 uint dummy_gc_count_before;
447 uint dummy_gclocker_retry_count = 0;
448 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
449 }
450
451 HeapWord*
452 G1CollectedHeap::mem_allocate(size_t word_size,
453 bool* gc_overhead_limit_was_exceeded) {
454 assert_heap_not_locked_and_not_at_safepoint();
455
456 // Loop until the allocation is satisfied, or unsatisfied after GC.
457 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
458 uint gc_count_before;
459
460 HeapWord* result = NULL;
461 if (!is_humongous(word_size)) {
462 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
463 } else {
464 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
465 }
466 if (result != NULL) {
467 return result;
468 }
469
470 // Create the garbage collection operation...
471 VM_G1CollectForAllocation op(gc_count_before, word_size);
472 op.set_allocation_context(AllocationContext::current());
473
474 // ...and get the VM thread to execute it.
475 VMThread::execute(&op);
476
477 if (op.prologue_succeeded() && op.pause_succeeded()) {
478 // If the operation was successful we'll return the result even
479 // if it is NULL. If the allocation attempt failed immediately
480 // after a Full GC, it's unlikely we'll be able to allocate now.
481 HeapWord* result = op.result();
482 if (result != NULL && !is_humongous(word_size)) {
483 // Allocations that take place on VM operations do not do any
484 // card dirtying and we have to do it here. We only have to do
485 // this for non-humongous allocations, though.
486 dirty_young_block(result, word_size);
487 }
488 return result;
489 } else {
490 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
491 return NULL;
492 }
493 assert(op.result() == NULL,
494 "the result should be NULL if the VM op did not succeed");
495 }
496
497 // Give a warning if we seem to be looping forever.
498 if ((QueuedAllocationWarningCount > 0) &&
499 (try_count % QueuedAllocationWarningCount == 0)) {
500 log_warning(gc)("G1CollectedHeap::mem_allocate retries %d times", try_count);
501 }
502 }
503
504 ShouldNotReachHere();
505 return NULL;
506 }
507
508 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
509 AllocationContext_t context,
510 uint* gc_count_before_ret,
511 uint* gclocker_retry_count_ret) {
512 // Make sure you read the note in attempt_allocation_humongous().
513
514 assert_heap_not_locked_and_not_at_safepoint();
515 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
516 "be called for humongous allocation requests");
517
518 // We should only get here after the first-level allocation attempt
519 // (attempt_allocation()) failed to allocate.
520
521 // We will loop until a) we manage to successfully perform the
522 // allocation or b) we successfully schedule a collection which
523 // fails to perform the allocation. b) is the only case when we'll
524 // return NULL.
525 HeapWord* result = NULL;
526 for (int try_count = 1; /* we'll return */; try_count += 1) {
527 bool should_try_gc;
528 uint gc_count_before;
529
530 {
531 MutexLockerEx x(Heap_lock);
532 result = _allocator->attempt_allocation_locked(word_size, context);
533 if (result != NULL) {
534 return result;
535 }
536
537 if (GCLocker::is_active_and_needs_gc()) {
538 if (g1_policy()->can_expand_young_list()) {
539 // No need for an ergo verbose message here,
540 // can_expand_young_list() does this when it returns true.
541 result = _allocator->attempt_allocation_force(word_size, context);
542 if (result != NULL) {
543 return result;
544 }
545 }
546 should_try_gc = false;
547 } else {
548 // The GCLocker may not be active but the GCLocker initiated
549 // GC may not yet have been performed (GCLocker::needs_gc()
550 // returns true). In this case we do not try this GC and
551 // wait until the GCLocker initiated GC is performed, and
552 // then retry the allocation.
553 if (GCLocker::needs_gc()) {
554 should_try_gc = false;
555 } else {
556 // Read the GC count while still holding the Heap_lock.
557 gc_count_before = total_collections();
558 should_try_gc = true;
559 }
560 }
561 }
562
563 if (should_try_gc) {
564 bool succeeded;
565 result = do_collection_pause(word_size, gc_count_before, &succeeded,
566 GCCause::_g1_inc_collection_pause);
567 if (result != NULL) {
568 assert(succeeded, "only way to get back a non-NULL result");
569 return result;
570 }
571
572 if (succeeded) {
573 // If we get here we successfully scheduled a collection which
574 // failed to allocate. No point in trying to allocate
575 // further. We'll just return NULL.
576 MutexLockerEx x(Heap_lock);
577 *gc_count_before_ret = total_collections();
578 return NULL;
579 }
580 } else {
581 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
582 MutexLockerEx x(Heap_lock);
583 *gc_count_before_ret = total_collections();
584 return NULL;
585 }
586 // The GCLocker is either active or the GCLocker initiated
587 // GC has not yet been performed. Stall until it is and
588 // then retry the allocation.
589 GCLocker::stall_until_clear();
590 (*gclocker_retry_count_ret) += 1;
591 }
592
593 // We can reach here if we were unsuccessful in scheduling a
594 // collection (because another thread beat us to it) or if we were
595 // stalled due to the GC locker. In either can we should retry the
596 // allocation attempt in case another thread successfully
597 // performed a collection and reclaimed enough space. We do the
598 // first attempt (without holding the Heap_lock) here and the
599 // follow-on attempt will be at the start of the next loop
600 // iteration (after taking the Heap_lock).
601 result = _allocator->attempt_allocation(word_size, context);
602 if (result != NULL) {
603 return result;
604 }
605
606 // Give a warning if we seem to be looping forever.
607 if ((QueuedAllocationWarningCount > 0) &&
608 (try_count % QueuedAllocationWarningCount == 0)) {
609 log_warning(gc)("G1CollectedHeap::attempt_allocation_slow() "
610 "retries %d times", try_count);
611 }
612 }
613
614 ShouldNotReachHere();
615 return NULL;
616 }
617
618 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
619 assert_at_safepoint(true /* should_be_vm_thread */);
620 if (_archive_allocator == NULL) {
621 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
622 }
623 }
624
625 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
626 // Allocations in archive regions cannot be of a size that would be considered
627 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
628 // may be different at archive-restore time.
629 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
630 }
631
632 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
633 assert_at_safepoint(true /* should_be_vm_thread */);
634 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
635 if (is_archive_alloc_too_large(word_size)) {
636 return NULL;
637 }
638 return _archive_allocator->archive_mem_allocate(word_size);
639 }
640
641 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
642 size_t end_alignment_in_bytes) {
643 assert_at_safepoint(true /* should_be_vm_thread */);
644 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
645
646 // Call complete_archive to do the real work, filling in the MemRegion
647 // array with the archive regions.
648 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
649 delete _archive_allocator;
650 _archive_allocator = NULL;
651 }
652
653 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
654 assert(ranges != NULL, "MemRegion array NULL");
655 assert(count != 0, "No MemRegions provided");
656 MemRegion reserved = _hrm.reserved();
657 for (size_t i = 0; i < count; i++) {
658 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
659 return false;
660 }
661 }
662 return true;
663 }
664
665 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
666 size_t count,
667 bool open) {
668 assert(!is_init_completed(), "Expect to be called at JVM init time");
669 assert(ranges != NULL, "MemRegion array NULL");
670 assert(count != 0, "No MemRegions provided");
671 MutexLockerEx x(Heap_lock);
672
673 MemRegion reserved = _hrm.reserved();
674 HeapWord* prev_last_addr = NULL;
675 HeapRegion* prev_last_region = NULL;
676
677 // Temporarily disable pretouching of heap pages. This interface is used
678 // when mmap'ing archived heap data in, so pre-touching is wasted.
679 FlagSetting fs(AlwaysPreTouch, false);
680
681 // Enable archive object checking used by G1MarkSweep. We have to let it know
682 // about each archive range, so that objects in those ranges aren't marked.
683 G1ArchiveAllocator::enable_archive_object_check();
684
685 // For each specified MemRegion range, allocate the corresponding G1
686 // regions and mark them as archive regions. We expect the ranges
687 // in ascending starting address order, without overlap.
688 for (size_t i = 0; i < count; i++) {
689 MemRegion curr_range = ranges[i];
690 HeapWord* start_address = curr_range.start();
691 size_t word_size = curr_range.word_size();
692 HeapWord* last_address = curr_range.last();
693 size_t commits = 0;
694
695 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
696 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
697 p2i(start_address), p2i(last_address));
698 guarantee(start_address > prev_last_addr,
699 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
700 p2i(start_address), p2i(prev_last_addr));
701 prev_last_addr = last_address;
702
703 // Check for ranges that start in the same G1 region in which the previous
704 // range ended, and adjust the start address so we don't try to allocate
705 // the same region again. If the current range is entirely within that
706 // region, skip it, just adjusting the recorded top.
707 HeapRegion* start_region = _hrm.addr_to_region(start_address);
708 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
709 start_address = start_region->end();
710 if (start_address > last_address) {
711 increase_used(word_size * HeapWordSize);
712 start_region->set_top(last_address + 1);
713 continue;
714 }
715 start_region->set_top(start_address);
716 curr_range = MemRegion(start_address, last_address + 1);
717 start_region = _hrm.addr_to_region(start_address);
718 }
719
720 // Perform the actual region allocation, exiting if it fails.
721 // Then note how much new space we have allocated.
722 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
723 return false;
724 }
725 increase_used(word_size * HeapWordSize);
726 if (commits != 0) {
727 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
728 HeapRegion::GrainWords * HeapWordSize * commits);
729
730 }
731
732 // Mark each G1 region touched by the range as archive, add it to
733 // the old set, and set the allocation context and top.
734 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
735 HeapRegion* last_region = _hrm.addr_to_region(last_address);
736 prev_last_region = last_region;
737
738 while (curr_region != NULL) {
739 assert(curr_region->is_empty() && !curr_region->is_pinned(),
740 "Region already in use (index %u)", curr_region->hrm_index());
741 curr_region->set_allocation_context(AllocationContext::system());
742 if (open) {
743 curr_region->set_open_archive();
744 } else {
745 curr_region->set_closed_archive();
746 }
747 _hr_printer.alloc(curr_region);
748 _old_set.add(curr_region);
749 HeapWord* top;
750 HeapRegion* next_region;
751 if (curr_region != last_region) {
752 top = curr_region->end();
753 next_region = _hrm.next_region_in_heap(curr_region);
754 } else {
755 top = last_address + 1;
756 next_region = NULL;
757 }
758 curr_region->set_top(top);
759 curr_region->set_first_dead(top);
760 curr_region->set_end_of_live(top);
761 curr_region = next_region;
762 }
763
764 // Notify mark-sweep of the archive
765 G1ArchiveAllocator::set_range_archive(curr_range, open);
766 }
767 return true;
768 }
769
770 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
771 assert(!is_init_completed(), "Expect to be called at JVM init time");
772 assert(ranges != NULL, "MemRegion array NULL");
773 assert(count != 0, "No MemRegions provided");
774 MemRegion reserved = _hrm.reserved();
775 HeapWord *prev_last_addr = NULL;
776 HeapRegion* prev_last_region = NULL;
777
778 // For each MemRegion, create filler objects, if needed, in the G1 regions
779 // that contain the address range. The address range actually within the
780 // MemRegion will not be modified. That is assumed to have been initialized
781 // elsewhere, probably via an mmap of archived heap data.
782 MutexLockerEx x(Heap_lock);
783 for (size_t i = 0; i < count; i++) {
784 HeapWord* start_address = ranges[i].start();
785 HeapWord* last_address = ranges[i].last();
786
787 assert(reserved.contains(start_address) && reserved.contains(last_address),
788 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
789 p2i(start_address), p2i(last_address));
790 assert(start_address > prev_last_addr,
791 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
792 p2i(start_address), p2i(prev_last_addr));
793
794 HeapRegion* start_region = _hrm.addr_to_region(start_address);
795 HeapRegion* last_region = _hrm.addr_to_region(last_address);
796 HeapWord* bottom_address = start_region->bottom();
797
798 // Check for a range beginning in the same region in which the
799 // previous one ended.
800 if (start_region == prev_last_region) {
801 bottom_address = prev_last_addr + 1;
802 }
803
804 // Verify that the regions were all marked as archive regions by
805 // alloc_archive_regions.
806 HeapRegion* curr_region = start_region;
807 while (curr_region != NULL) {
808 guarantee(curr_region->is_archive(),
809 "Expected archive region at index %u", curr_region->hrm_index());
810 if (curr_region != last_region) {
811 curr_region = _hrm.next_region_in_heap(curr_region);
812 } else {
813 curr_region = NULL;
814 }
815 }
816
817 prev_last_addr = last_address;
818 prev_last_region = last_region;
819
820 // Fill the memory below the allocated range with dummy object(s),
821 // if the region bottom does not match the range start, or if the previous
822 // range ended within the same G1 region, and there is a gap.
823 if (start_address != bottom_address) {
824 size_t fill_size = pointer_delta(start_address, bottom_address);
825 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
826 increase_used(fill_size * HeapWordSize);
827 }
828 }
829 }
830
831 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
832 uint* gc_count_before_ret,
833 uint* gclocker_retry_count_ret) {
834 assert_heap_not_locked_and_not_at_safepoint();
835 assert(!is_humongous(word_size), "attempt_allocation() should not "
836 "be called for humongous allocation requests");
837
838 AllocationContext_t context = AllocationContext::current();
839 HeapWord* result = _allocator->attempt_allocation(word_size, context);
840
841 if (result == NULL) {
842 result = attempt_allocation_slow(word_size,
843 context,
844 gc_count_before_ret,
845 gclocker_retry_count_ret);
846 }
847 assert_heap_not_locked();
848 if (result != NULL) {
849 dirty_young_block(result, word_size);
850 }
851 return result;
852 }
853
854 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
855 assert(!is_init_completed(), "Expect to be called at JVM init time");
856 assert(ranges != NULL, "MemRegion array NULL");
857 assert(count != 0, "No MemRegions provided");
858 MemRegion reserved = _hrm.reserved();
859 HeapWord* prev_last_addr = NULL;
860 HeapRegion* prev_last_region = NULL;
861 size_t size_used = 0;
862 size_t uncommitted_regions = 0;
863
864 // For each Memregion, free the G1 regions that constitute it, and
865 // notify mark-sweep that the range is no longer to be considered 'archive.'
866 MutexLockerEx x(Heap_lock);
867 for (size_t i = 0; i < count; i++) {
868 HeapWord* start_address = ranges[i].start();
869 HeapWord* last_address = ranges[i].last();
870
871 assert(reserved.contains(start_address) && reserved.contains(last_address),
872 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
873 p2i(start_address), p2i(last_address));
874 assert(start_address > prev_last_addr,
875 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
876 p2i(start_address), p2i(prev_last_addr));
877 size_used += ranges[i].byte_size();
878 prev_last_addr = last_address;
879
880 HeapRegion* start_region = _hrm.addr_to_region(start_address);
881 HeapRegion* last_region = _hrm.addr_to_region(last_address);
882
883 // Check for ranges that start in the same G1 region in which the previous
884 // range ended, and adjust the start address so we don't try to free
885 // the same region again. If the current range is entirely within that
886 // region, skip it.
887 if (start_region == prev_last_region) {
888 start_address = start_region->end();
889 if (start_address > last_address) {
890 continue;
891 }
892 start_region = _hrm.addr_to_region(start_address);
893 }
894 prev_last_region = last_region;
895
896 // After verifying that each region was marked as an archive region by
897 // alloc_archive_regions, set it free and empty and uncommit it.
898 HeapRegion* curr_region = start_region;
899 while (curr_region != NULL) {
900 guarantee(curr_region->is_archive(),
901 "Expected archive region at index %u", curr_region->hrm_index());
902 uint curr_index = curr_region->hrm_index();
903 _old_set.remove(curr_region);
904 curr_region->set_free();
905 curr_region->set_top(curr_region->bottom());
906 if (curr_region != last_region) {
907 curr_region = _hrm.next_region_in_heap(curr_region);
908 } else {
909 curr_region = NULL;
910 }
911 _hrm.shrink_at(curr_index, 1);
912 uncommitted_regions++;
913 }
914
915 // Notify mark-sweep that this is no longer an archive range.
916 G1ArchiveAllocator::set_range_archive(ranges[i], false);
917 }
918
919 if (uncommitted_regions != 0) {
920 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
921 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
922 }
923 decrease_used(size_used);
924 }
925
926 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
927 uint* gc_count_before_ret,
928 uint* gclocker_retry_count_ret) {
929 // The structure of this method has a lot of similarities to
930 // attempt_allocation_slow(). The reason these two were not merged
931 // into a single one is that such a method would require several "if
932 // allocation is not humongous do this, otherwise do that"
933 // conditional paths which would obscure its flow. In fact, an early
934 // version of this code did use a unified method which was harder to
935 // follow and, as a result, it had subtle bugs that were hard to
936 // track down. So keeping these two methods separate allows each to
937 // be more readable. It will be good to keep these two in sync as
938 // much as possible.
939
940 assert_heap_not_locked_and_not_at_safepoint();
941 assert(is_humongous(word_size), "attempt_allocation_humongous() "
942 "should only be called for humongous allocations");
943
944 // Humongous objects can exhaust the heap quickly, so we should check if we
945 // need to start a marking cycle at each humongous object allocation. We do
946 // the check before we do the actual allocation. The reason for doing it
947 // before the allocation is that we avoid having to keep track of the newly
948 // allocated memory while we do a GC.
949 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
950 word_size)) {
951 collect(GCCause::_g1_humongous_allocation);
952 }
953
954 // We will loop until a) we manage to successfully perform the
955 // allocation or b) we successfully schedule a collection which
956 // fails to perform the allocation. b) is the only case when we'll
957 // return NULL.
958 HeapWord* result = NULL;
959 for (int try_count = 1; /* we'll return */; try_count += 1) {
960 bool should_try_gc;
961 uint gc_count_before;
962
963 {
964 MutexLockerEx x(Heap_lock);
965
966 // Given that humongous objects are not allocated in young
967 // regions, we'll first try to do the allocation without doing a
968 // collection hoping that there's enough space in the heap.
969 result = humongous_obj_allocate(word_size, AllocationContext::current());
970 if (result != NULL) {
971 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
972 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
973 return result;
974 }
975
976 if (GCLocker::is_active_and_needs_gc()) {
977 should_try_gc = false;
978 } else {
979 // The GCLocker may not be active but the GCLocker initiated
980 // GC may not yet have been performed (GCLocker::needs_gc()
981 // returns true). In this case we do not try this GC and
982 // wait until the GCLocker initiated GC is performed, and
983 // then retry the allocation.
984 if (GCLocker::needs_gc()) {
985 should_try_gc = false;
986 } else {
987 // Read the GC count while still holding the Heap_lock.
988 gc_count_before = total_collections();
989 should_try_gc = true;
990 }
991 }
992 }
993
994 if (should_try_gc) {
995 // If we failed to allocate the humongous object, we should try to
996 // do a collection pause (if we're allowed) in case it reclaims
997 // enough space for the allocation to succeed after the pause.
998
999 bool succeeded;
1000 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1001 GCCause::_g1_humongous_allocation);
1002 if (result != NULL) {
1003 assert(succeeded, "only way to get back a non-NULL result");
1004 return result;
1005 }
1006
1007 if (succeeded) {
1008 // If we get here we successfully scheduled a collection which
1009 // failed to allocate. No point in trying to allocate
1010 // further. We'll just return NULL.
1011 MutexLockerEx x(Heap_lock);
1012 *gc_count_before_ret = total_collections();
1013 return NULL;
1014 }
1015 } else {
1016 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1017 MutexLockerEx x(Heap_lock);
1018 *gc_count_before_ret = total_collections();
1019 return NULL;
1020 }
1021 // The GCLocker is either active or the GCLocker initiated
1022 // GC has not yet been performed. Stall until it is and
1023 // then retry the allocation.
1024 GCLocker::stall_until_clear();
1025 (*gclocker_retry_count_ret) += 1;
1026 }
1027
1028 // We can reach here if we were unsuccessful in scheduling a
1029 // collection (because another thread beat us to it) or if we were
1030 // stalled due to the GC locker. In either can we should retry the
1031 // allocation attempt in case another thread successfully
1032 // performed a collection and reclaimed enough space. Give a
1033 // warning if we seem to be looping forever.
1034
1035 if ((QueuedAllocationWarningCount > 0) &&
1036 (try_count % QueuedAllocationWarningCount == 0)) {
1037 log_warning(gc)("G1CollectedHeap::attempt_allocation_humongous() "
1038 "retries %d times", try_count);
1039 }
1040 }
1041
1042 ShouldNotReachHere();
1043 return NULL;
1044 }
1045
1046 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1047 AllocationContext_t context,
1048 bool expect_null_mutator_alloc_region) {
1049 assert_at_safepoint(true /* should_be_vm_thread */);
1050 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1051 "the current alloc region was unexpectedly found to be non-NULL");
1052
1053 if (!is_humongous(word_size)) {
1054 return _allocator->attempt_allocation_locked(word_size, context);
1055 } else {
1056 HeapWord* result = humongous_obj_allocate(word_size, context);
1057 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1058 collector_state()->set_initiate_conc_mark_if_possible(true);
1059 }
1060 return result;
1061 }
1062
1063 ShouldNotReachHere();
1064 }
1065
1066 class PostCompactionPrinterClosure: public HeapRegionClosure {
1067 private:
1068 G1HRPrinter* _hr_printer;
1069 public:
1070 bool doHeapRegion(HeapRegion* hr) {
1071 assert(!hr->is_young(), "not expecting to find young regions");
1072 _hr_printer->post_compaction(hr);
1073 return false;
1074 }
1075
1076 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1077 : _hr_printer(hr_printer) { }
1078 };
1079
1080 void G1CollectedHeap::print_hrm_post_compaction() {
1081 if (_hr_printer.is_active()) {
1082 PostCompactionPrinterClosure cl(hr_printer());
1083 heap_region_iterate(&cl);
1084 }
1085
1086 }
1087
1088 void G1CollectedHeap::abort_concurrent_cycle() {
1089 // Note: When we have a more flexible GC logging framework that
1090 // allows us to add optional attributes to a GC log record we
1091 // could consider timing and reporting how long we wait in the
1092 // following two methods.
1093 wait_while_free_regions_coming();
1094 // If we start the compaction before the CM threads finish
1095 // scanning the root regions we might trip them over as we'll
1096 // be moving objects / updating references. So let's wait until
1097 // they are done. By telling them to abort, they should complete
1098 // early.
1099 _cm->root_regions()->abort();
1100 _cm->root_regions()->wait_until_scan_finished();
1101 append_secondary_free_list_if_not_empty_with_lock();
1102
1103 // Disable discovery and empty the discovered lists
1104 // for the CM ref processor.
1105 ref_processor_cm()->disable_discovery();
1106 ref_processor_cm()->abandon_partial_discovery();
1107 ref_processor_cm()->verify_no_references_recorded();
1108
1109 // Abandon current iterations of concurrent marking and concurrent
1110 // refinement, if any are in progress.
1111 concurrent_mark()->abort();
1112 }
1113
1114 void G1CollectedHeap::prepare_heap_for_full_collection() {
1115 // Make sure we'll choose a new allocation region afterwards.
1116 _allocator->release_mutator_alloc_region();
1117 _allocator->abandon_gc_alloc_regions();
1118 g1_rem_set()->cleanupHRRS();
1119
1120 // We may have added regions to the current incremental collection
1121 // set between the last GC or pause and now. We need to clear the
1122 // incremental collection set and then start rebuilding it afresh
1123 // after this full GC.
1124 abandon_collection_set(collection_set());
1125
1126 tear_down_region_sets(false /* free_list_only */);
1127 collector_state()->set_gcs_are_young(true);
1128 }
1129
1130 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1131 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1132 assert(used() == recalculate_used(), "Should be equal");
1133 _verifier->verify_region_sets_optional();
1134 _verifier->verify_before_gc();
1135 _verifier->check_bitmaps("Full GC Start");
1136 }
1137
1138 void G1CollectedHeap::prepare_heap_for_mutators() {
1139 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1140 ClassLoaderDataGraph::purge();
1141 MetaspaceAux::verify_metrics();
1142
1143 // Prepare heap for normal collections.
1144 assert(num_free_regions() == 0, "we should not have added any free regions");
1145 rebuild_region_sets(false /* free_list_only */);
1146 abort_refinement();
1147 resize_if_necessary_after_full_collection();
1148
1149 // Rebuild the strong code root lists for each region
1150 rebuild_strong_code_roots();
1151
1152 // Start a new incremental collection set for the next pause
1153 start_new_collection_set();
1154
1155 _allocator->init_mutator_alloc_region();
1156
1157 // Post collection state updates.
1158 MetaspaceGC::compute_new_size();
1159 }
1160
1161 void G1CollectedHeap::abort_refinement() {
1162 if (_hot_card_cache->use_cache()) {
1163 _hot_card_cache->reset_card_counts();
1164 _hot_card_cache->reset_hot_cache();
1165 }
1166
1167 // Discard all remembered set updates.
1168 JavaThread::dirty_card_queue_set().abandon_logs();
1169 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1170 }
1171
1172 void G1CollectedHeap::verify_after_full_collection() {
1173 check_gc_time_stamps();
1174 _hrm.verify_optional();
1175 _verifier->verify_region_sets_optional();
1176 _verifier->verify_after_gc();
1177 // Clear the previous marking bitmap, if needed for bitmap verification.
1178 // Note we cannot do this when we clear the next marking bitmap in
1179 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1180 // objects marked during a full GC against the previous bitmap.
1181 // But we need to clear it before calling check_bitmaps below since
1182 // the full GC has compacted objects and updated TAMS but not updated
1183 // the prev bitmap.
1184 if (G1VerifyBitmaps) {
1185 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1186 _cm->clear_prev_bitmap(workers());
1187 }
1188 _verifier->check_bitmaps("Full GC End");
1189
1190 // At this point there should be no regions in the
1191 // entire heap tagged as young.
1192 assert(check_young_list_empty(), "young list should be empty at this point");
1193
1194 // Note: since we've just done a full GC, concurrent
1195 // marking is no longer active. Therefore we need not
1196 // re-enable reference discovery for the CM ref processor.
1197 // That will be done at the start of the next marking cycle.
1198 // We also know that the STW processor should no longer
1199 // discover any new references.
1200 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1201 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1202 ref_processor_stw()->verify_no_references_recorded();
1203 ref_processor_cm()->verify_no_references_recorded();
1204 }
1205
1206 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1207 print_hrm_post_compaction();
1208 heap_transition->print();
1209 print_heap_after_gc();
1210 print_heap_regions();
1211 #ifdef TRACESPINNING
1212 ParallelTaskTerminator::print_termination_counts();
1213 #endif
1214 }
1215
1216 void G1CollectedHeap::do_full_collection_inner(G1FullGCScope* scope) {
1217 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1218 g1_policy()->record_full_collection_start();
1219
1220 print_heap_before_gc();
1221 print_heap_regions();
1222
1223 abort_concurrent_cycle();
1224 verify_before_full_collection(scope->is_explicit_gc());
1225
1226 gc_prologue(true);
1227 prepare_heap_for_full_collection();
1228
1229 G1SerialFullCollector serial(scope, ref_processor_stw());
1230 serial.prepare_collection();
1231 serial.collect();
1232 serial.complete_collection();
1233
1234 prepare_heap_for_mutators();
1235
1236 g1_policy()->record_full_collection_end();
1237 gc_epilogue(true);
1238
1239 // Post collection verification.
1240 verify_after_full_collection();
1241
1242 // Post collection logging.
1243 // We should do this after we potentially resize the heap so
1244 // that all the COMMIT / UNCOMMIT events are generated before
1245 // the compaction events.
1246 print_heap_after_full_collection(scope->heap_transition());
1247 }
1248
1249 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1250 bool clear_all_soft_refs) {
1251 assert_at_safepoint(true /* should_be_vm_thread */);
1252
1253 if (GCLocker::check_active_before_gc()) {
1254 // Full GC was not completed.
1255 return false;
1256 }
1257
1258 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1259 collector_policy()->should_clear_all_soft_refs();
1260
1261 G1FullGCScope scope(explicit_gc, do_clear_all_soft_refs);
1262 do_full_collection_inner(&scope);
1263
1264 // Full collection was successfully completed.
1265 return true;
1266 }
1267
1268 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1269 // Currently, there is no facility in the do_full_collection(bool) API to notify
1270 // the caller that the collection did not succeed (e.g., because it was locked
1271 // out by the GC locker). So, right now, we'll ignore the return value.
1272 bool dummy = do_full_collection(true, /* explicit_gc */
1273 clear_all_soft_refs);
1274 }
1275
1276 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1277 // Include bytes that will be pre-allocated to support collections, as "used".
1278 const size_t used_after_gc = used();
1279 const size_t capacity_after_gc = capacity();
1280 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1281
1282 // This is enforced in arguments.cpp.
1283 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1284 "otherwise the code below doesn't make sense");
1285
1286 // We don't have floating point command-line arguments
1287 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1288 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1289 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1290 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1291
1292 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1293 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1294
1295 // We have to be careful here as these two calculations can overflow
1296 // 32-bit size_t's.
1297 double used_after_gc_d = (double) used_after_gc;
1298 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1299 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1300
1301 // Let's make sure that they are both under the max heap size, which
1302 // by default will make them fit into a size_t.
1303 double desired_capacity_upper_bound = (double) max_heap_size;
1304 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1305 desired_capacity_upper_bound);
1306 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1307 desired_capacity_upper_bound);
1308
1309 // We can now safely turn them into size_t's.
1310 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1311 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1312
1313 // This assert only makes sense here, before we adjust them
1314 // with respect to the min and max heap size.
1315 assert(minimum_desired_capacity <= maximum_desired_capacity,
1316 "minimum_desired_capacity = " SIZE_FORMAT ", "
1317 "maximum_desired_capacity = " SIZE_FORMAT,
1318 minimum_desired_capacity, maximum_desired_capacity);
1319
1320 // Should not be greater than the heap max size. No need to adjust
1321 // it with respect to the heap min size as it's a lower bound (i.e.,
1322 // we'll try to make the capacity larger than it, not smaller).
1323 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1324 // Should not be less than the heap min size. No need to adjust it
1325 // with respect to the heap max size as it's an upper bound (i.e.,
1326 // we'll try to make the capacity smaller than it, not greater).
1327 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1328
1329 if (capacity_after_gc < minimum_desired_capacity) {
1330 // Don't expand unless it's significant
1331 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1332
1333 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1334 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1335 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1336
1337 expand(expand_bytes, _workers);
1338
1339 // No expansion, now see if we want to shrink
1340 } else if (capacity_after_gc > maximum_desired_capacity) {
1341 // Capacity too large, compute shrinking size
1342 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1343
1344 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1345 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1346 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1347
1348 shrink(shrink_bytes);
1349 }
1350 }
1351
1352 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1353 AllocationContext_t context,
1354 bool do_gc,
1355 bool clear_all_soft_refs,
1356 bool expect_null_mutator_alloc_region,
1357 bool* gc_succeeded) {
1358 *gc_succeeded = true;
1359 // Let's attempt the allocation first.
1360 HeapWord* result =
1361 attempt_allocation_at_safepoint(word_size,
1362 context,
1363 expect_null_mutator_alloc_region);
1364 if (result != NULL) {
1365 assert(*gc_succeeded, "sanity");
1366 return result;
1367 }
1368
1369 // In a G1 heap, we're supposed to keep allocation from failing by
1370 // incremental pauses. Therefore, at least for now, we'll favor
1371 // expansion over collection. (This might change in the future if we can
1372 // do something smarter than full collection to satisfy a failed alloc.)
1373 result = expand_and_allocate(word_size, context);
1374 if (result != NULL) {
1375 assert(*gc_succeeded, "sanity");
1376 return result;
1377 }
1378
1379 if (do_gc) {
1380 // Expansion didn't work, we'll try to do a Full GC.
1381 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1382 clear_all_soft_refs);
1383 }
1384
1385 return NULL;
1386 }
1387
1388 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1389 AllocationContext_t context,
1390 bool* succeeded) {
1391 assert_at_safepoint(true /* should_be_vm_thread */);
1392
1393 // Attempts to allocate followed by Full GC.
1394 HeapWord* result =
1395 satisfy_failed_allocation_helper(word_size,
1396 context,
1397 true, /* do_gc */
1398 false, /* clear_all_soft_refs */
1399 false, /* expect_null_mutator_alloc_region */
1400 succeeded);
1401
1402 if (result != NULL || !*succeeded) {
1403 return result;
1404 }
1405
1406 // Attempts to allocate followed by Full GC that will collect all soft references.
1407 result = satisfy_failed_allocation_helper(word_size,
1408 context,
1409 true, /* do_gc */
1410 true, /* clear_all_soft_refs */
1411 true, /* expect_null_mutator_alloc_region */
1412 succeeded);
1413
1414 if (result != NULL || !*succeeded) {
1415 return result;
1416 }
1417
1418 // Attempts to allocate, no GC
1419 result = satisfy_failed_allocation_helper(word_size,
1420 context,
1421 false, /* do_gc */
1422 false, /* clear_all_soft_refs */
1423 true, /* expect_null_mutator_alloc_region */
1424 succeeded);
1425
1426 if (result != NULL) {
1427 assert(*succeeded, "sanity");
1428 return result;
1429 }
1430
1431 assert(!collector_policy()->should_clear_all_soft_refs(),
1432 "Flag should have been handled and cleared prior to this point");
1433
1434 // What else? We might try synchronous finalization later. If the total
1435 // space available is large enough for the allocation, then a more
1436 // complete compaction phase than we've tried so far might be
1437 // appropriate.
1438 assert(*succeeded, "sanity");
1439 return NULL;
1440 }
1441
1442 // Attempting to expand the heap sufficiently
1443 // to support an allocation of the given "word_size". If
1444 // successful, perform the allocation and return the address of the
1445 // allocated block, or else "NULL".
1446
1447 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1448 assert_at_safepoint(true /* should_be_vm_thread */);
1449
1450 _verifier->verify_region_sets_optional();
1451
1452 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1453 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1454 word_size * HeapWordSize);
1455
1456
1457 if (expand(expand_bytes, _workers)) {
1458 _hrm.verify_optional();
1459 _verifier->verify_region_sets_optional();
1460 return attempt_allocation_at_safepoint(word_size,
1461 context,
1462 false /* expect_null_mutator_alloc_region */);
1463 }
1464 return NULL;
1465 }
1466
1467 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1468 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1469 aligned_expand_bytes = align_up(aligned_expand_bytes,
1470 HeapRegion::GrainBytes);
1471
1472 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1473 expand_bytes, aligned_expand_bytes);
1474
1475 if (is_maximal_no_gc()) {
1476 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1477 return false;
1478 }
1479
1480 double expand_heap_start_time_sec = os::elapsedTime();
1481 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1482 assert(regions_to_expand > 0, "Must expand by at least one region");
1483
1484 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1485 if (expand_time_ms != NULL) {
1486 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1487 }
1488
1489 if (expanded_by > 0) {
1490 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1491 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1492 g1_policy()->record_new_heap_size(num_regions());
1493 } else {
1494 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1495
1496 // The expansion of the virtual storage space was unsuccessful.
1497 // Let's see if it was because we ran out of swap.
1498 if (G1ExitOnExpansionFailure &&
1499 _hrm.available() >= regions_to_expand) {
1500 // We had head room...
1501 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1502 }
1503 }
1504 return regions_to_expand > 0;
1505 }
1506
1507 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1508 size_t aligned_shrink_bytes =
1509 ReservedSpace::page_align_size_down(shrink_bytes);
1510 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1511 HeapRegion::GrainBytes);
1512 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1513
1514 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1515 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1516
1517
1518 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",
1519 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1520 if (num_regions_removed > 0) {
1521 g1_policy()->record_new_heap_size(num_regions());
1522 } else {
1523 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1524 }
1525 }
1526
1527 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1528 _verifier->verify_region_sets_optional();
1529
1530 // We should only reach here at the end of a Full GC which means we
1531 // should not not be holding to any GC alloc regions. The method
1532 // below will make sure of that and do any remaining clean up.
1533 _allocator->abandon_gc_alloc_regions();
1534
1535 // Instead of tearing down / rebuilding the free lists here, we
1536 // could instead use the remove_all_pending() method on free_list to
1537 // remove only the ones that we need to remove.
1538 tear_down_region_sets(true /* free_list_only */);
1539 shrink_helper(shrink_bytes);
1540 rebuild_region_sets(true /* free_list_only */);
1541
1542 _hrm.verify_optional();
1543 _verifier->verify_region_sets_optional();
1544 }
1545
1546 // Public methods.
1547
1548 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1549 CollectedHeap(),
1550 _collector_policy(collector_policy),
1551 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1552 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1553 _g1_policy(create_g1_policy(_gc_timer_stw)),
1554 _collection_set(this, _g1_policy),
1555 _dirty_card_queue_set(false),
1556 _is_alive_closure_cm(this),
1557 _is_alive_closure_stw(this),
1558 _ref_processor_cm(NULL),
1559 _ref_processor_stw(NULL),
1560 _bot(NULL),
1561 _hot_card_cache(NULL),
1562 _g1_rem_set(NULL),
1563 _cg1r(NULL),
1564 _g1mm(NULL),
1565 _preserved_marks_set(true /* in_c_heap */),
1566 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1567 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1568 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1569 _humongous_reclaim_candidates(),
1570 _has_humongous_reclaim_candidates(false),
1571 _archive_allocator(NULL),
1572 _free_regions_coming(false),
1573 _gc_time_stamp(0),
1574 _summary_bytes_used(0),
1575 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1576 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1577 _expand_heap_after_alloc_failure(true),
1578 _old_marking_cycles_started(0),
1579 _old_marking_cycles_completed(0),
1580 _in_cset_fast_test() {
1581
1582 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1583 /* are_GC_task_threads */true,
1584 /* are_ConcurrentGC_threads */false);
1585 _workers->initialize_workers();
1586 _verifier = new G1HeapVerifier(this);
1587
1588 _allocator = G1Allocator::create_allocator(this);
1589
1590 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1591
1592 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1593
1594 // Override the default _filler_array_max_size so that no humongous filler
1595 // objects are created.
1596 _filler_array_max_size = _humongous_object_threshold_in_words;
1597
1598 uint n_queues = ParallelGCThreads;
1599 _task_queues = new RefToScanQueueSet(n_queues);
1600
1601 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1602
1603 for (uint i = 0; i < n_queues; i++) {
1604 RefToScanQueue* q = new RefToScanQueue();
1605 q->initialize();
1606 _task_queues->register_queue(i, q);
1607 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1608 }
1609
1610 // Initialize the G1EvacuationFailureALot counters and flags.
1611 NOT_PRODUCT(reset_evacuation_should_fail();)
1612
1613 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1614 }
1615
1616 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1617 size_t size,
1618 size_t translation_factor) {
1619 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1620 // Allocate a new reserved space, preferring to use large pages.
1621 ReservedSpace rs(size, preferred_page_size);
1622 G1RegionToSpaceMapper* result =
1623 G1RegionToSpaceMapper::create_mapper(rs,
1624 size,
1625 rs.alignment(),
1626 HeapRegion::GrainBytes,
1627 translation_factor,
1628 mtGC);
1629
1630 os::trace_page_sizes_for_requested_size(description,
1631 size,
1632 preferred_page_size,
1633 rs.alignment(),
1634 rs.base(),
1635 rs.size());
1636
1637 return result;
1638 }
1639
1640 jint G1CollectedHeap::initialize_concurrent_refinement() {
1641 jint ecode = JNI_OK;
1642 _cg1r = ConcurrentG1Refine::create(&ecode);
1643 return ecode;
1644 }
1645
1646 jint G1CollectedHeap::initialize() {
1647 CollectedHeap::pre_initialize();
1648 os::enable_vtime();
1649
1650 // Necessary to satisfy locking discipline assertions.
1651
1652 MutexLocker x(Heap_lock);
1653
1654 // While there are no constraints in the GC code that HeapWordSize
1655 // be any particular value, there are multiple other areas in the
1656 // system which believe this to be true (e.g. oop->object_size in some
1657 // cases incorrectly returns the size in wordSize units rather than
1658 // HeapWordSize).
1659 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1660
1661 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1662 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1663 size_t heap_alignment = collector_policy()->heap_alignment();
1664
1665 // Ensure that the sizes are properly aligned.
1666 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1667 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1669
1670 // Reserve the maximum.
1671
1672 // When compressed oops are enabled, the preferred heap base
1673 // is calculated by subtracting the requested size from the
1674 // 32Gb boundary and using the result as the base address for
1675 // heap reservation. If the requested size is not aligned to
1676 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1677 // into the ReservedHeapSpace constructor) then the actual
1678 // base of the reserved heap may end up differing from the
1679 // address that was requested (i.e. the preferred heap base).
1680 // If this happens then we could end up using a non-optimal
1681 // compressed oops mode.
1682
1683 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1684 heap_alignment);
1685
1686 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1687
1688 // Create the barrier set for the entire reserved region.
1689 G1SATBCardTableLoggingModRefBS* bs
1690 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1691 bs->initialize();
1692 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1693 set_barrier_set(bs);
1694
1695 // Create the hot card cache.
1696 _hot_card_cache = new G1HotCardCache(this);
1697
1698 // Carve out the G1 part of the heap.
1699 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1700 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1701 G1RegionToSpaceMapper* heap_storage =
1702 G1RegionToSpaceMapper::create_mapper(g1_rs,
1703 g1_rs.size(),
1704 page_size,
1705 HeapRegion::GrainBytes,
1706 1,
1707 mtJavaHeap);
1708 os::trace_page_sizes("Heap",
1709 collector_policy()->min_heap_byte_size(),
1710 max_byte_size,
1711 page_size,
1712 heap_rs.base(),
1713 heap_rs.size());
1714 heap_storage->set_mapping_changed_listener(&_listener);
1715
1716 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1717 G1RegionToSpaceMapper* bot_storage =
1718 create_aux_memory_mapper("Block Offset Table",
1719 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1720 G1BlockOffsetTable::heap_map_factor());
1721
1722 G1RegionToSpaceMapper* cardtable_storage =
1723 create_aux_memory_mapper("Card Table",
1724 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1725 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1726
1727 G1RegionToSpaceMapper* card_counts_storage =
1728 create_aux_memory_mapper("Card Counts Table",
1729 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1730 G1CardCounts::heap_map_factor());
1731
1732 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1733 G1RegionToSpaceMapper* prev_bitmap_storage =
1734 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1735 G1RegionToSpaceMapper* next_bitmap_storage =
1736 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1737
1738 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1739 g1_barrier_set()->initialize(cardtable_storage);
1740 // Do later initialization work for concurrent refinement.
1741 _hot_card_cache->initialize(card_counts_storage);
1742
1743 // 6843694 - ensure that the maximum region index can fit
1744 // in the remembered set structures.
1745 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1746 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1747
1748 // Also create a G1 rem set.
1749 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1750 _g1_rem_set->initialize(max_capacity(), max_regions());
1751
1752 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1753 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1754 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1755 "too many cards per region");
1756
1757 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1758
1759 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1760
1761 {
1762 HeapWord* start = _hrm.reserved().start();
1763 HeapWord* end = _hrm.reserved().end();
1764 size_t granularity = HeapRegion::GrainBytes;
1765
1766 _in_cset_fast_test.initialize(start, end, granularity);
1767 _humongous_reclaim_candidates.initialize(start, end, granularity);
1768 }
1769
1770 // Create the G1ConcurrentMark data structure and thread.
1771 // (Must do this late, so that "max_regions" is defined.)
1772 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1773 if (_cm == NULL || !_cm->completed_initialization()) {
1774 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1775 return JNI_ENOMEM;
1776 }
1777 _cmThread = _cm->cmThread();
1778
1779 // Now expand into the initial heap size.
1780 if (!expand(init_byte_size, _workers)) {
1781 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1782 return JNI_ENOMEM;
1783 }
1784
1785 // Perform any initialization actions delegated to the policy.
1786 g1_policy()->init(this, &_collection_set);
1787
1788 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1789 SATB_Q_FL_lock,
1790 G1SATBProcessCompletedThreshold,
1791 Shared_SATB_Q_lock);
1792
1793 jint ecode = initialize_concurrent_refinement();
1794 if (ecode != JNI_OK) {
1795 return ecode;
1796 }
1797
1798 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1799 DirtyCardQ_FL_lock,
1800 (int)concurrent_g1_refine()->yellow_zone(),
1801 (int)concurrent_g1_refine()->red_zone(),
1802 Shared_DirtyCardQ_lock,
1803 NULL, // fl_owner
1804 true); // init_free_ids
1805
1806 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1807 DirtyCardQ_FL_lock,
1808 -1, // never trigger processing
1809 -1, // no limit on length
1810 Shared_DirtyCardQ_lock,
1811 &JavaThread::dirty_card_queue_set());
1812
1813 // Here we allocate the dummy HeapRegion that is required by the
1814 // G1AllocRegion class.
1815 HeapRegion* dummy_region = _hrm.get_dummy_region();
1816
1817 // We'll re-use the same region whether the alloc region will
1818 // require BOT updates or not and, if it doesn't, then a non-young
1819 // region will complain that it cannot support allocations without
1820 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1821 dummy_region->set_eden();
1822 // Make sure it's full.
1823 dummy_region->set_top(dummy_region->end());
1824 G1AllocRegion::setup(this, dummy_region);
1825
1826 _allocator->init_mutator_alloc_region();
1827
1828 // Do create of the monitoring and management support so that
1829 // values in the heap have been properly initialized.
1830 _g1mm = new G1MonitoringSupport(this);
1831
1832 G1StringDedup::initialize();
1833
1834 _preserved_marks_set.init(ParallelGCThreads);
1835
1836 _collection_set.initialize(max_regions());
1837
1838 return JNI_OK;
1839 }
1840
1841 void G1CollectedHeap::stop() {
1842 // Stop all concurrent threads. We do this to make sure these threads
1843 // do not continue to execute and access resources (e.g. logging)
1844 // that are destroyed during shutdown.
1845 _cg1r->stop();
1846 _cmThread->stop();
1847 if (G1StringDedup::is_enabled()) {
1848 G1StringDedup::stop();
1849 }
1850 }
1851
1852 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1853 return HeapRegion::max_region_size();
1854 }
1855
1856 void G1CollectedHeap::post_initialize() {
1857 ref_processing_init();
1858 }
1859
1860 void G1CollectedHeap::ref_processing_init() {
1861 // Reference processing in G1 currently works as follows:
1862 //
1863 // * There are two reference processor instances. One is
1864 // used to record and process discovered references
1865 // during concurrent marking; the other is used to
1866 // record and process references during STW pauses
1867 // (both full and incremental).
1868 // * Both ref processors need to 'span' the entire heap as
1869 // the regions in the collection set may be dotted around.
1870 //
1871 // * For the concurrent marking ref processor:
1872 // * Reference discovery is enabled at initial marking.
1873 // * Reference discovery is disabled and the discovered
1874 // references processed etc during remarking.
1875 // * Reference discovery is MT (see below).
1876 // * Reference discovery requires a barrier (see below).
1877 // * Reference processing may or may not be MT
1878 // (depending on the value of ParallelRefProcEnabled
1879 // and ParallelGCThreads).
1880 // * A full GC disables reference discovery by the CM
1881 // ref processor and abandons any entries on it's
1882 // discovered lists.
1883 //
1884 // * For the STW processor:
1885 // * Non MT discovery is enabled at the start of a full GC.
1886 // * Processing and enqueueing during a full GC is non-MT.
1887 // * During a full GC, references are processed after marking.
1888 //
1889 // * Discovery (may or may not be MT) is enabled at the start
1890 // of an incremental evacuation pause.
1891 // * References are processed near the end of a STW evacuation pause.
1892 // * For both types of GC:
1893 // * Discovery is atomic - i.e. not concurrent.
1894 // * Reference discovery will not need a barrier.
1895
1896 MemRegion mr = reserved_region();
1897
1898 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1899
1900 // Concurrent Mark ref processor
1901 _ref_processor_cm =
1902 new ReferenceProcessor(mr, // span
1903 mt_processing,
1904 // mt processing
1905 ParallelGCThreads,
1906 // degree of mt processing
1907 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
1908 // mt discovery
1909 MAX2(ParallelGCThreads, ConcGCThreads),
1910 // degree of mt discovery
1911 false,
1912 // Reference discovery is not atomic
1913 &_is_alive_closure_cm);
1914 // is alive closure
1915 // (for efficiency/performance)
1916
1917 // STW ref processor
1918 _ref_processor_stw =
1919 new ReferenceProcessor(mr, // span
1920 mt_processing,
1921 // mt processing
1922 ParallelGCThreads,
1923 // degree of mt processing
1924 (ParallelGCThreads > 1),
1925 // mt discovery
1926 ParallelGCThreads,
1927 // degree of mt discovery
1928 true,
1929 // Reference discovery is atomic
1930 &_is_alive_closure_stw);
1931 // is alive closure
1932 // (for efficiency/performance)
1933 }
1934
1935 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1936 return _collector_policy;
1937 }
1938
1939 size_t G1CollectedHeap::capacity() const {
1940 return _hrm.length() * HeapRegion::GrainBytes;
1941 }
1942
1943 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
1944 hr->reset_gc_time_stamp();
1945 }
1946
1947 #ifndef PRODUCT
1948
1949 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
1950 private:
1951 unsigned _gc_time_stamp;
1952 bool _failures;
1953
1954 public:
1955 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
1956 _gc_time_stamp(gc_time_stamp), _failures(false) { }
1957
1958 virtual bool doHeapRegion(HeapRegion* hr) {
1959 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
1960 if (_gc_time_stamp != region_gc_time_stamp) {
1961 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
1962 region_gc_time_stamp, _gc_time_stamp);
1963 _failures = true;
1964 }
1965 return false;
1966 }
1967
1968 bool failures() { return _failures; }
1969 };
1970
1971 void G1CollectedHeap::check_gc_time_stamps() {
1972 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
1973 heap_region_iterate(&cl);
1974 guarantee(!cl.failures(), "all GC time stamps should have been reset");
1975 }
1976 #endif // PRODUCT
1977
1978 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1979 _hot_card_cache->drain(cl, worker_i);
1980 }
1981
1982 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1983 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
1984 size_t n_completed_buffers = 0;
1985 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1986 n_completed_buffers++;
1987 }
1988 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
1989 dcqs.clear_n_completed_buffers();
1990 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1991 }
1992
1993 // Computes the sum of the storage used by the various regions.
1994 size_t G1CollectedHeap::used() const {
1995 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1996 if (_archive_allocator != NULL) {
1997 result += _archive_allocator->used();
1998 }
1999 return result;
2000 }
2001
2002 size_t G1CollectedHeap::used_unlocked() const {
2003 return _summary_bytes_used;
2004 }
2005
2006 class SumUsedClosure: public HeapRegionClosure {
2007 size_t _used;
2008 public:
2009 SumUsedClosure() : _used(0) {}
2010 bool doHeapRegion(HeapRegion* r) {
2011 _used += r->used();
2012 return false;
2013 }
2014 size_t result() { return _used; }
2015 };
2016
2017 size_t G1CollectedHeap::recalculate_used() const {
2018 double recalculate_used_start = os::elapsedTime();
2019
2020 SumUsedClosure blk;
2021 heap_region_iterate(&blk);
2022
2023 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2024 return blk.result();
2025 }
2026
2027 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2028 switch (cause) {
2029 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2030 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2031 case GCCause::_update_allocation_context_stats_inc: return true;
2032 case GCCause::_wb_conc_mark: return true;
2033 default : return false;
2034 }
2035 }
2036
2037 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2038 switch (cause) {
2039 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2040 case GCCause::_g1_humongous_allocation: return true;
2041 default: return is_user_requested_concurrent_full_gc(cause);
2042 }
2043 }
2044
2045 #ifndef PRODUCT
2046 void G1CollectedHeap::allocate_dummy_regions() {
2047 // Let's fill up most of the region
2048 size_t word_size = HeapRegion::GrainWords - 1024;
2049 // And as a result the region we'll allocate will be humongous.
2050 guarantee(is_humongous(word_size), "sanity");
2051
2052 // _filler_array_max_size is set to humongous object threshold
2053 // but temporarily change it to use CollectedHeap::fill_with_object().
2054 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2055
2056 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2057 // Let's use the existing mechanism for the allocation
2058 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2059 AllocationContext::system());
2060 if (dummy_obj != NULL) {
2061 MemRegion mr(dummy_obj, word_size);
2062 CollectedHeap::fill_with_object(mr);
2063 } else {
2064 // If we can't allocate once, we probably cannot allocate
2065 // again. Let's get out of the loop.
2066 break;
2067 }
2068 }
2069 }
2070 #endif // !PRODUCT
2071
2072 void G1CollectedHeap::increment_old_marking_cycles_started() {
2073 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2074 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2075 "Wrong marking cycle count (started: %d, completed: %d)",
2076 _old_marking_cycles_started, _old_marking_cycles_completed);
2077
2078 _old_marking_cycles_started++;
2079 }
2080
2081 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2082 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2083
2084 // We assume that if concurrent == true, then the caller is a
2085 // concurrent thread that was joined the Suspendible Thread
2086 // Set. If there's ever a cheap way to check this, we should add an
2087 // assert here.
2088
2089 // Given that this method is called at the end of a Full GC or of a
2090 // concurrent cycle, and those can be nested (i.e., a Full GC can
2091 // interrupt a concurrent cycle), the number of full collections
2092 // completed should be either one (in the case where there was no
2093 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2094 // behind the number of full collections started.
2095
2096 // This is the case for the inner caller, i.e. a Full GC.
2097 assert(concurrent ||
2098 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2099 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2100 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2101 "is inconsistent with _old_marking_cycles_completed = %u",
2102 _old_marking_cycles_started, _old_marking_cycles_completed);
2103
2104 // This is the case for the outer caller, i.e. the concurrent cycle.
2105 assert(!concurrent ||
2106 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2107 "for outer caller (concurrent cycle): "
2108 "_old_marking_cycles_started = %u "
2109 "is inconsistent with _old_marking_cycles_completed = %u",
2110 _old_marking_cycles_started, _old_marking_cycles_completed);
2111
2112 _old_marking_cycles_completed += 1;
2113
2114 // We need to clear the "in_progress" flag in the CM thread before
2115 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2116 // is set) so that if a waiter requests another System.gc() it doesn't
2117 // incorrectly see that a marking cycle is still in progress.
2118 if (concurrent) {
2119 _cmThread->set_idle();
2120 }
2121
2122 // This notify_all() will ensure that a thread that called
2123 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2124 // and it's waiting for a full GC to finish will be woken up. It is
2125 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2126 FullGCCount_lock->notify_all();
2127 }
2128
2129 void G1CollectedHeap::collect(GCCause::Cause cause) {
2130 assert_heap_not_locked();
2131
2132 uint gc_count_before;
2133 uint old_marking_count_before;
2134 uint full_gc_count_before;
2135 bool retry_gc;
2136
2137 do {
2138 retry_gc = false;
2139
2140 {
2141 MutexLocker ml(Heap_lock);
2142
2143 // Read the GC count while holding the Heap_lock
2144 gc_count_before = total_collections();
2145 full_gc_count_before = total_full_collections();
2146 old_marking_count_before = _old_marking_cycles_started;
2147 }
2148
2149 if (should_do_concurrent_full_gc(cause)) {
2150 // Schedule an initial-mark evacuation pause that will start a
2151 // concurrent cycle. We're setting word_size to 0 which means that
2152 // we are not requesting a post-GC allocation.
2153 VM_G1IncCollectionPause op(gc_count_before,
2154 0, /* word_size */
2155 true, /* should_initiate_conc_mark */
2156 g1_policy()->max_pause_time_ms(),
2157 cause);
2158 op.set_allocation_context(AllocationContext::current());
2159
2160 VMThread::execute(&op);
2161 if (!op.pause_succeeded()) {
2162 if (old_marking_count_before == _old_marking_cycles_started) {
2163 retry_gc = op.should_retry_gc();
2164 } else {
2165 // A Full GC happened while we were trying to schedule the
2166 // initial-mark GC. No point in starting a new cycle given
2167 // that the whole heap was collected anyway.
2168 }
2169
2170 if (retry_gc) {
2171 if (GCLocker::is_active_and_needs_gc()) {
2172 GCLocker::stall_until_clear();
2173 }
2174 }
2175 }
2176 } else {
2177 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2178 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2179
2180 // Schedule a standard evacuation pause. We're setting word_size
2181 // to 0 which means that we are not requesting a post-GC allocation.
2182 VM_G1IncCollectionPause op(gc_count_before,
2183 0, /* word_size */
2184 false, /* should_initiate_conc_mark */
2185 g1_policy()->max_pause_time_ms(),
2186 cause);
2187 VMThread::execute(&op);
2188 } else {
2189 // Schedule a Full GC.
2190 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2191 VMThread::execute(&op);
2192 }
2193 }
2194 } while (retry_gc);
2195 }
2196
2197 bool G1CollectedHeap::is_in(const void* p) const {
2198 if (_hrm.reserved().contains(p)) {
2199 // Given that we know that p is in the reserved space,
2200 // heap_region_containing() should successfully
2201 // return the containing region.
2202 HeapRegion* hr = heap_region_containing(p);
2203 return hr->is_in(p);
2204 } else {
2205 return false;
2206 }
2207 }
2208
2209 #ifdef ASSERT
2210 bool G1CollectedHeap::is_in_exact(const void* p) const {
2211 bool contains = reserved_region().contains(p);
2212 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2213 if (contains && available) {
2214 return true;
2215 } else {
2216 return false;
2217 }
2218 }
2219 #endif
2220
2221 // Iteration functions.
2222
2223 // Iterates an ObjectClosure over all objects within a HeapRegion.
2224
2225 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2226 ObjectClosure* _cl;
2227 public:
2228 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2229 bool doHeapRegion(HeapRegion* r) {
2230 if (!r->is_continues_humongous()) {
2231 r->object_iterate(_cl);
2232 }
2233 return false;
2234 }
2235 };
2236
2237 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2238 IterateObjectClosureRegionClosure blk(cl);
2239 heap_region_iterate(&blk);
2240 }
2241
2242 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2243 _hrm.iterate(cl);
2244 }
2245
2246 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2247 uint worker_id,
2248 HeapRegionClaimer *hrclaimer) const {
2249 _hrm.par_iterate(cl, worker_id, hrclaimer);
2250 }
2251
2252 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2253 _collection_set.iterate(cl);
2254 }
2255
2256 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2257 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2258 }
2259
2260 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2261 HeapRegion* result = _hrm.next_region_in_heap(from);
2262 while (result != NULL && result->is_pinned()) {
2263 result = _hrm.next_region_in_heap(result);
2264 }
2265 return result;
2266 }
2267
2268 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2269 HeapRegion* hr = heap_region_containing(addr);
2270 return hr->block_start(addr);
2271 }
2272
2273 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2274 HeapRegion* hr = heap_region_containing(addr);
2275 return hr->block_size(addr);
2276 }
2277
2278 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2279 HeapRegion* hr = heap_region_containing(addr);
2280 return hr->block_is_obj(addr);
2281 }
2282
2283 bool G1CollectedHeap::supports_tlab_allocation() const {
2284 return true;
2285 }
2286
2287 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2288 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2289 }
2290
2291 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2292 return _eden.length() * HeapRegion::GrainBytes;
2293 }
2294
2295 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2296 // must be equal to the humongous object limit.
2297 size_t G1CollectedHeap::max_tlab_size() const {
2298 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2299 }
2300
2301 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2302 AllocationContext_t context = AllocationContext::current();
2303 return _allocator->unsafe_max_tlab_alloc(context);
2304 }
2305
2306 size_t G1CollectedHeap::max_capacity() const {
2307 return _hrm.reserved().byte_size();
2308 }
2309
2310 jlong G1CollectedHeap::millis_since_last_gc() {
2311 // See the notes in GenCollectedHeap::millis_since_last_gc()
2312 // for more information about the implementation.
2313 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2314 _g1_policy->collection_pause_end_millis();
2315 if (ret_val < 0) {
2316 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2317 ". returning zero instead.", ret_val);
2318 return 0;
2319 }
2320 return ret_val;
2321 }
2322
2323 void G1CollectedHeap::prepare_for_verify() {
2324 _verifier->prepare_for_verify();
2325 }
2326
2327 void G1CollectedHeap::verify(VerifyOption vo) {
2328 _verifier->verify(vo);
2329 }
2330
2331 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2332 return true;
2333 }
2334
2335 const char* const* G1CollectedHeap::concurrent_phases() const {
2336 return _cmThread->concurrent_phases();
2337 }
2338
2339 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2340 return _cmThread->request_concurrent_phase(phase);
2341 }
2342
2343 class PrintRegionClosure: public HeapRegionClosure {
2344 outputStream* _st;
2345 public:
2346 PrintRegionClosure(outputStream* st) : _st(st) {}
2347 bool doHeapRegion(HeapRegion* r) {
2348 r->print_on(_st);
2349 return false;
2350 }
2351 };
2352
2353 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2354 const HeapRegion* hr,
2355 const VerifyOption vo) const {
2356 switch (vo) {
2357 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2358 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2359 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2360 default: ShouldNotReachHere();
2361 }
2362 return false; // keep some compilers happy
2363 }
2364
2365 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2366 const VerifyOption vo) const {
2367 switch (vo) {
2368 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2369 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2370 case VerifyOption_G1UseMarkWord: {
2371 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2372 return !obj->is_gc_marked() && !hr->is_archive();
2373 }
2374 default: ShouldNotReachHere();
2375 }
2376 return false; // keep some compilers happy
2377 }
2378
2379 void G1CollectedHeap::print_heap_regions() const {
2380 LogTarget(Trace, gc, heap, region) lt;
2381 if (lt.is_enabled()) {
2382 LogStream ls(lt);
2383 print_regions_on(&ls);
2384 }
2385 }
2386
2387 void G1CollectedHeap::print_on(outputStream* st) const {
2388 st->print(" %-20s", "garbage-first heap");
2389 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2390 capacity()/K, used_unlocked()/K);
2391 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2392 p2i(_hrm.reserved().start()),
2393 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2394 p2i(_hrm.reserved().end()));
2395 st->cr();
2396 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2397 uint young_regions = young_regions_count();
2398 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2399 (size_t) young_regions * HeapRegion::GrainBytes / K);
2400 uint survivor_regions = survivor_regions_count();
2401 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2402 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2403 st->cr();
2404 MetaspaceAux::print_on(st);
2405 }
2406
2407 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2408 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2409 "HS=humongous(starts), HC=humongous(continues), "
2410 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2411 "AC=allocation context, "
2412 "TAMS=top-at-mark-start (previous, next)");
2413 PrintRegionClosure blk(st);
2414 heap_region_iterate(&blk);
2415 }
2416
2417 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2418 print_on(st);
2419
2420 // Print the per-region information.
2421 print_regions_on(st);
2422 }
2423
2424 void G1CollectedHeap::print_on_error(outputStream* st) const {
2425 this->CollectedHeap::print_on_error(st);
2426
2427 if (_cm != NULL) {
2428 st->cr();
2429 _cm->print_on_error(st);
2430 }
2431 }
2432
2433 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2434 workers()->print_worker_threads_on(st);
2435 _cmThread->print_on(st);
2436 st->cr();
2437 _cm->print_worker_threads_on(st);
2438 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2439 if (G1StringDedup::is_enabled()) {
2440 G1StringDedup::print_worker_threads_on(st);
2441 }
2442 }
2443
2444 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2445 workers()->threads_do(tc);
2446 tc->do_thread(_cmThread);
2447 _cm->threads_do(tc);
2448 _cg1r->threads_do(tc); // also iterates over the sample thread
2449 if (G1StringDedup::is_enabled()) {
2450 G1StringDedup::threads_do(tc);
2451 }
2452 }
2453
2454 void G1CollectedHeap::print_tracing_info() const {
2455 g1_rem_set()->print_summary_info();
2456 concurrent_mark()->print_summary_info();
2457 }
2458
2459 #ifndef PRODUCT
2460 // Helpful for debugging RSet issues.
2461
2462 class PrintRSetsClosure : public HeapRegionClosure {
2463 private:
2464 const char* _msg;
2465 size_t _occupied_sum;
2466
2467 public:
2468 bool doHeapRegion(HeapRegion* r) {
2469 HeapRegionRemSet* hrrs = r->rem_set();
2470 size_t occupied = hrrs->occupied();
2471 _occupied_sum += occupied;
2472
2473 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2474 if (occupied == 0) {
2475 tty->print_cr(" RSet is empty");
2476 } else {
2477 hrrs->print();
2478 }
2479 tty->print_cr("----------");
2480 return false;
2481 }
2482
2483 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2484 tty->cr();
2485 tty->print_cr("========================================");
2486 tty->print_cr("%s", msg);
2487 tty->cr();
2488 }
2489
2490 ~PrintRSetsClosure() {
2491 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2492 tty->print_cr("========================================");
2493 tty->cr();
2494 }
2495 };
2496
2497 void G1CollectedHeap::print_cset_rsets() {
2498 PrintRSetsClosure cl("Printing CSet RSets");
2499 collection_set_iterate(&cl);
2500 }
2501
2502 void G1CollectedHeap::print_all_rsets() {
2503 PrintRSetsClosure cl("Printing All RSets");;
2504 heap_region_iterate(&cl);
2505 }
2506 #endif // PRODUCT
2507
2508 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2509
2510 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2511 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2512 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2513
2514 size_t eden_capacity_bytes =
2515 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2516
2517 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2518 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2519 eden_capacity_bytes, survivor_used_bytes, num_regions());
2520 }
2521
2522 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2523 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2524 stats->unused(), stats->used(), stats->region_end_waste(),
2525 stats->regions_filled(), stats->direct_allocated(),
2526 stats->failure_used(), stats->failure_waste());
2527 }
2528
2529 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2530 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2531 gc_tracer->report_gc_heap_summary(when, heap_summary);
2532
2533 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2534 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2535 }
2536
2537 G1CollectedHeap* G1CollectedHeap::heap() {
2538 CollectedHeap* heap = Universe::heap();
2539 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2540 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2541 return (G1CollectedHeap*)heap;
2542 }
2543
2544 void G1CollectedHeap::gc_prologue(bool full) {
2545 // always_do_update_barrier = false;
2546 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2547
2548 // This summary needs to be printed before incrementing total collections.
2549 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2550
2551 // Update common counters.
2552 increment_total_collections(full /* full gc */);
2553 if (full) {
2554 increment_old_marking_cycles_started();
2555 reset_gc_time_stamp();
2556 } else {
2557 increment_gc_time_stamp();
2558 }
2559
2560 // Fill TLAB's and such
2561 double start = os::elapsedTime();
2562 accumulate_statistics_all_tlabs();
2563 ensure_parsability(true);
2564 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2565 }
2566
2567 void G1CollectedHeap::gc_epilogue(bool full) {
2568 // Update common counters.
2569 if (full) {
2570 // Update the number of full collections that have been completed.
2571 increment_old_marking_cycles_completed(false /* concurrent */);
2572 }
2573
2574 // We are at the end of the GC. Total collections has already been increased.
2575 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2576
2577 // FIXME: what is this about?
2578 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2579 // is set.
2580 #if defined(COMPILER2) || INCLUDE_JVMCI
2581 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2582 #endif
2583 // always_do_update_barrier = true;
2584
2585 double start = os::elapsedTime();
2586 resize_all_tlabs();
2587 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2588
2589 allocation_context_stats().update(full);
2590
2591 MemoryService::track_memory_usage();
2592 // We have just completed a GC. Update the soft reference
2593 // policy with the new heap occupancy
2594 Universe::update_heap_info_at_gc();
2595 }
2596
2597 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2598 uint gc_count_before,
2599 bool* succeeded,
2600 GCCause::Cause gc_cause) {
2601 assert_heap_not_locked_and_not_at_safepoint();
2602 VM_G1IncCollectionPause op(gc_count_before,
2603 word_size,
2604 false, /* should_initiate_conc_mark */
2605 g1_policy()->max_pause_time_ms(),
2606 gc_cause);
2607
2608 op.set_allocation_context(AllocationContext::current());
2609 VMThread::execute(&op);
2610
2611 HeapWord* result = op.result();
2612 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2613 assert(result == NULL || ret_succeeded,
2614 "the result should be NULL if the VM did not succeed");
2615 *succeeded = ret_succeeded;
2616
2617 assert_heap_not_locked();
2618 return result;
2619 }
2620
2621 void
2622 G1CollectedHeap::doConcurrentMark() {
2623 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2624 if (!_cmThread->in_progress()) {
2625 _cmThread->set_started();
2626 CGC_lock->notify();
2627 }
2628 }
2629
2630 size_t G1CollectedHeap::pending_card_num() {
2631 size_t extra_cards = 0;
2632 JavaThread *curr = Threads::first();
2633 while (curr != NULL) {
2634 DirtyCardQueue& dcq = curr->dirty_card_queue();
2635 extra_cards += dcq.size();
2636 curr = curr->next();
2637 }
2638 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2639 size_t buffer_size = dcqs.buffer_size();
2640 size_t buffer_num = dcqs.completed_buffers_num();
2641
2642 return buffer_size * buffer_num + extra_cards;
2643 }
2644
2645 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2646 private:
2647 size_t _total_humongous;
2648 size_t _candidate_humongous;
2649
2650 DirtyCardQueue _dcq;
2651
2652 // We don't nominate objects with many remembered set entries, on
2653 // the assumption that such objects are likely still live.
2654 bool is_remset_small(HeapRegion* region) const {
2655 HeapRegionRemSet* const rset = region->rem_set();
2656 return G1EagerReclaimHumongousObjectsWithStaleRefs
2657 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2658 : rset->is_empty();
2659 }
2660
2661 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2662 assert(region->is_starts_humongous(), "Must start a humongous object");
2663
2664 oop obj = oop(region->bottom());
2665
2666 // Dead objects cannot be eager reclaim candidates. Due to class
2667 // unloading it is unsafe to query their classes so we return early.
2668 if (heap->is_obj_dead(obj, region)) {
2669 return false;
2670 }
2671
2672 // Candidate selection must satisfy the following constraints
2673 // while concurrent marking is in progress:
2674 //
2675 // * In order to maintain SATB invariants, an object must not be
2676 // reclaimed if it was allocated before the start of marking and
2677 // has not had its references scanned. Such an object must have
2678 // its references (including type metadata) scanned to ensure no
2679 // live objects are missed by the marking process. Objects
2680 // allocated after the start of concurrent marking don't need to
2681 // be scanned.
2682 //
2683 // * An object must not be reclaimed if it is on the concurrent
2684 // mark stack. Objects allocated after the start of concurrent
2685 // marking are never pushed on the mark stack.
2686 //
2687 // Nominating only objects allocated after the start of concurrent
2688 // marking is sufficient to meet both constraints. This may miss
2689 // some objects that satisfy the constraints, but the marking data
2690 // structures don't support efficiently performing the needed
2691 // additional tests or scrubbing of the mark stack.
2692 //
2693 // However, we presently only nominate is_typeArray() objects.
2694 // A humongous object containing references induces remembered
2695 // set entries on other regions. In order to reclaim such an
2696 // object, those remembered sets would need to be cleaned up.
2697 //
2698 // We also treat is_typeArray() objects specially, allowing them
2699 // to be reclaimed even if allocated before the start of
2700 // concurrent mark. For this we rely on mark stack insertion to
2701 // exclude is_typeArray() objects, preventing reclaiming an object
2702 // that is in the mark stack. We also rely on the metadata for
2703 // such objects to be built-in and so ensured to be kept live.
2704 // Frequent allocation and drop of large binary blobs is an
2705 // important use case for eager reclaim, and this special handling
2706 // may reduce needed headroom.
2707
2708 return obj->is_typeArray() && is_remset_small(region);
2709 }
2710
2711 public:
2712 RegisterHumongousWithInCSetFastTestClosure()
2713 : _total_humongous(0),
2714 _candidate_humongous(0),
2715 _dcq(&JavaThread::dirty_card_queue_set()) {
2716 }
2717
2718 virtual bool doHeapRegion(HeapRegion* r) {
2719 if (!r->is_starts_humongous()) {
2720 return false;
2721 }
2722 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2723
2724 bool is_candidate = humongous_region_is_candidate(g1h, r);
2725 uint rindex = r->hrm_index();
2726 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2727 if (is_candidate) {
2728 _candidate_humongous++;
2729 g1h->register_humongous_region_with_cset(rindex);
2730 // Is_candidate already filters out humongous object with large remembered sets.
2731 // If we have a humongous object with a few remembered sets, we simply flush these
2732 // remembered set entries into the DCQS. That will result in automatic
2733 // re-evaluation of their remembered set entries during the following evacuation
2734 // phase.
2735 if (!r->rem_set()->is_empty()) {
2736 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2737 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2738 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2739 HeapRegionRemSetIterator hrrs(r->rem_set());
2740 size_t card_index;
2741 while (hrrs.has_next(card_index)) {
2742 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2743 // The remembered set might contain references to already freed
2744 // regions. Filter out such entries to avoid failing card table
2745 // verification.
2746 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2747 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2748 *card_ptr = CardTableModRefBS::dirty_card_val();
2749 _dcq.enqueue(card_ptr);
2750 }
2751 }
2752 }
2753 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2754 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2755 hrrs.n_yielded(), r->rem_set()->occupied());
2756 r->rem_set()->clear_locked();
2757 }
2758 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2759 }
2760 _total_humongous++;
2761
2762 return false;
2763 }
2764
2765 size_t total_humongous() const { return _total_humongous; }
2766 size_t candidate_humongous() const { return _candidate_humongous; }
2767
2768 void flush_rem_set_entries() { _dcq.flush(); }
2769 };
2770
2771 void G1CollectedHeap::register_humongous_regions_with_cset() {
2772 if (!G1EagerReclaimHumongousObjects) {
2773 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2774 return;
2775 }
2776 double time = os::elapsed_counter();
2777
2778 // Collect reclaim candidate information and register candidates with cset.
2779 RegisterHumongousWithInCSetFastTestClosure cl;
2780 heap_region_iterate(&cl);
2781
2782 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2783 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2784 cl.total_humongous(),
2785 cl.candidate_humongous());
2786 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2787
2788 // Finally flush all remembered set entries to re-check into the global DCQS.
2789 cl.flush_rem_set_entries();
2790 }
2791
2792 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2793 public:
2794 bool doHeapRegion(HeapRegion* hr) {
2795 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2796 hr->verify_rem_set();
2797 }
2798 return false;
2799 }
2800 };
2801
2802 uint G1CollectedHeap::num_task_queues() const {
2803 return _task_queues->size();
2804 }
2805
2806 #if TASKQUEUE_STATS
2807 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2808 st->print_raw_cr("GC Task Stats");
2809 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2810 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2811 }
2812
2813 void G1CollectedHeap::print_taskqueue_stats() const {
2814 if (!log_is_enabled(Trace, gc, task, stats)) {
2815 return;
2816 }
2817 Log(gc, task, stats) log;
2818 ResourceMark rm;
2819 LogStream ls(log.trace());
2820 outputStream* st = &ls;
2821
2822 print_taskqueue_stats_hdr(st);
2823
2824 TaskQueueStats totals;
2825 const uint n = num_task_queues();
2826 for (uint i = 0; i < n; ++i) {
2827 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2828 totals += task_queue(i)->stats;
2829 }
2830 st->print_raw("tot "); totals.print(st); st->cr();
2831
2832 DEBUG_ONLY(totals.verify());
2833 }
2834
2835 void G1CollectedHeap::reset_taskqueue_stats() {
2836 const uint n = num_task_queues();
2837 for (uint i = 0; i < n; ++i) {
2838 task_queue(i)->stats.reset();
2839 }
2840 }
2841 #endif // TASKQUEUE_STATS
2842
2843 void G1CollectedHeap::wait_for_root_region_scanning() {
2844 double scan_wait_start = os::elapsedTime();
2845 // We have to wait until the CM threads finish scanning the
2846 // root regions as it's the only way to ensure that all the
2847 // objects on them have been correctly scanned before we start
2848 // moving them during the GC.
2849 bool waited = _cm->root_regions()->wait_until_scan_finished();
2850 double wait_time_ms = 0.0;
2851 if (waited) {
2852 double scan_wait_end = os::elapsedTime();
2853 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2854 }
2855 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2856 }
2857
2858 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2859 private:
2860 G1HRPrinter* _hr_printer;
2861 public:
2862 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2863
2864 virtual bool doHeapRegion(HeapRegion* r) {
2865 _hr_printer->cset(r);
2866 return false;
2867 }
2868 };
2869
2870 void G1CollectedHeap::start_new_collection_set() {
2871 collection_set()->start_incremental_building();
2872
2873 clear_cset_fast_test();
2874
2875 guarantee(_eden.length() == 0, "eden should have been cleared");
2876 g1_policy()->transfer_survivors_to_cset(survivor());
2877 }
2878
2879 bool
2880 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2881 assert_at_safepoint(true /* should_be_vm_thread */);
2882 guarantee(!is_gc_active(), "collection is not reentrant");
2883
2884 if (GCLocker::check_active_before_gc()) {
2885 return false;
2886 }
2887
2888 _gc_timer_stw->register_gc_start();
2889
2890 GCIdMark gc_id_mark;
2891 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2892
2893 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2894 ResourceMark rm;
2895
2896 g1_policy()->note_gc_start();
2897
2898 wait_for_root_region_scanning();
2899
2900 print_heap_before_gc();
2901 print_heap_regions();
2902 trace_heap_before_gc(_gc_tracer_stw);
2903
2904 _verifier->verify_region_sets_optional();
2905 _verifier->verify_dirty_young_regions();
2906
2907 // We should not be doing initial mark unless the conc mark thread is running
2908 if (!_cmThread->should_terminate()) {
2909 // This call will decide whether this pause is an initial-mark
2910 // pause. If it is, during_initial_mark_pause() will return true
2911 // for the duration of this pause.
2912 g1_policy()->decide_on_conc_mark_initiation();
2913 }
2914
2915 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2916 assert(!collector_state()->during_initial_mark_pause() ||
2917 collector_state()->gcs_are_young(), "sanity");
2918
2919 // We also do not allow mixed GCs during marking.
2920 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
2921
2922 // Record whether this pause is an initial mark. When the current
2923 // thread has completed its logging output and it's safe to signal
2924 // the CM thread, the flag's value in the policy has been reset.
2925 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
2926
2927 // Inner scope for scope based logging, timers, and stats collection
2928 {
2929 EvacuationInfo evacuation_info;
2930
2931 if (collector_state()->during_initial_mark_pause()) {
2932 // We are about to start a marking cycle, so we increment the
2933 // full collection counter.
2934 increment_old_marking_cycles_started();
2935 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2936 }
2937
2938 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2939
2940 GCTraceCPUTime tcpu;
2941
2942 FormatBuffer<> gc_string("Pause ");
2943 if (collector_state()->during_initial_mark_pause()) {
2944 gc_string.append("Initial Mark");
2945 } else if (collector_state()->gcs_are_young()) {
2946 gc_string.append("Young");
2947 } else {
2948 gc_string.append("Mixed");
2949 }
2950 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2951
2952 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2953 workers()->active_workers(),
2954 Threads::number_of_non_daemon_threads());
2955 workers()->update_active_workers(active_workers);
2956 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2957
2958 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
2959 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
2960
2961 // If the secondary_free_list is not empty, append it to the
2962 // free_list. No need to wait for the cleanup operation to finish;
2963 // the region allocation code will check the secondary_free_list
2964 // and wait if necessary. If the G1StressConcRegionFreeing flag is
2965 // set, skip this step so that the region allocation code has to
2966 // get entries from the secondary_free_list.
2967 if (!G1StressConcRegionFreeing) {
2968 append_secondary_free_list_if_not_empty_with_lock();
2969 }
2970
2971 G1HeapTransition heap_transition(this);
2972 size_t heap_used_bytes_before_gc = used();
2973
2974 // Don't dynamically change the number of GC threads this early. A value of
2975 // 0 is used to indicate serial work. When parallel work is done,
2976 // it will be set.
2977
2978 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2979 IsGCActiveMark x;
2980
2981 gc_prologue(false);
2982
2983 if (VerifyRememberedSets) {
2984 log_info(gc, verify)("[Verifying RemSets before GC]");
2985 VerifyRegionRemSetClosure v_cl;
2986 heap_region_iterate(&v_cl);
2987 }
2988
2989 _verifier->verify_before_gc();
2990
2991 _verifier->check_bitmaps("GC Start");
2992
2993 #if defined(COMPILER2) || INCLUDE_JVMCI
2994 DerivedPointerTable::clear();
2995 #endif
2996
2997 // Please see comment in g1CollectedHeap.hpp and
2998 // G1CollectedHeap::ref_processing_init() to see how
2999 // reference processing currently works in G1.
3000
3001 // Enable discovery in the STW reference processor
3002 if (g1_policy()->should_process_references()) {
3003 ref_processor_stw()->enable_discovery();
3004 } else {
3005 ref_processor_stw()->disable_discovery();
3006 }
3007
3008 {
3009 // We want to temporarily turn off discovery by the
3010 // CM ref processor, if necessary, and turn it back on
3011 // on again later if we do. Using a scoped
3012 // NoRefDiscovery object will do this.
3013 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3014
3015 // Forget the current alloc region (we might even choose it to be part
3016 // of the collection set!).
3017 _allocator->release_mutator_alloc_region();
3018
3019 // This timing is only used by the ergonomics to handle our pause target.
3020 // It is unclear why this should not include the full pause. We will
3021 // investigate this in CR 7178365.
3022 //
3023 // Preserving the old comment here if that helps the investigation:
3024 //
3025 // The elapsed time induced by the start time below deliberately elides
3026 // the possible verification above.
3027 double sample_start_time_sec = os::elapsedTime();
3028
3029 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3030
3031 if (collector_state()->during_initial_mark_pause()) {
3032 concurrent_mark()->checkpointRootsInitialPre();
3033 }
3034
3035 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3036
3037 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3038
3039 // Make sure the remembered sets are up to date. This needs to be
3040 // done before register_humongous_regions_with_cset(), because the
3041 // remembered sets are used there to choose eager reclaim candidates.
3042 // If the remembered sets are not up to date we might miss some
3043 // entries that need to be handled.
3044 g1_rem_set()->cleanupHRRS();
3045
3046 register_humongous_regions_with_cset();
3047
3048 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3049
3050 // We call this after finalize_cset() to
3051 // ensure that the CSet has been finalized.
3052 _cm->verify_no_cset_oops();
3053
3054 if (_hr_printer.is_active()) {
3055 G1PrintCollectionSetClosure cl(&_hr_printer);
3056 _collection_set.iterate(&cl);
3057 }
3058
3059 // Initialize the GC alloc regions.
3060 _allocator->init_gc_alloc_regions(evacuation_info);
3061
3062 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3063 pre_evacuate_collection_set();
3064
3065 // Actually do the work...
3066 evacuate_collection_set(evacuation_info, &per_thread_states);
3067
3068 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3069
3070 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3071 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3072
3073 eagerly_reclaim_humongous_regions();
3074
3075 record_obj_copy_mem_stats();
3076 _survivor_evac_stats.adjust_desired_plab_sz();
3077 _old_evac_stats.adjust_desired_plab_sz();
3078
3079 double start = os::elapsedTime();
3080 start_new_collection_set();
3081 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3082
3083 if (evacuation_failed()) {
3084 set_used(recalculate_used());
3085 if (_archive_allocator != NULL) {
3086 _archive_allocator->clear_used();
3087 }
3088 for (uint i = 0; i < ParallelGCThreads; i++) {
3089 if (_evacuation_failed_info_array[i].has_failed()) {
3090 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3091 }
3092 }
3093 } else {
3094 // The "used" of the the collection set have already been subtracted
3095 // when they were freed. Add in the bytes evacuated.
3096 increase_used(g1_policy()->bytes_copied_during_gc());
3097 }
3098
3099 if (collector_state()->during_initial_mark_pause()) {
3100 // We have to do this before we notify the CM threads that
3101 // they can start working to make sure that all the
3102 // appropriate initialization is done on the CM object.
3103 concurrent_mark()->checkpointRootsInitialPost();
3104 collector_state()->set_mark_in_progress(true);
3105 // Note that we don't actually trigger the CM thread at
3106 // this point. We do that later when we're sure that
3107 // the current thread has completed its logging output.
3108 }
3109
3110 allocate_dummy_regions();
3111
3112 _allocator->init_mutator_alloc_region();
3113
3114 {
3115 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3116 if (expand_bytes > 0) {
3117 size_t bytes_before = capacity();
3118 // No need for an ergo logging here,
3119 // expansion_amount() does this when it returns a value > 0.
3120 double expand_ms;
3121 if (!expand(expand_bytes, _workers, &expand_ms)) {
3122 // We failed to expand the heap. Cannot do anything about it.
3123 }
3124 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3125 }
3126 }
3127
3128 // We redo the verification but now wrt to the new CSet which
3129 // has just got initialized after the previous CSet was freed.
3130 _cm->verify_no_cset_oops();
3131
3132 // This timing is only used by the ergonomics to handle our pause target.
3133 // It is unclear why this should not include the full pause. We will
3134 // investigate this in CR 7178365.
3135 double sample_end_time_sec = os::elapsedTime();
3136 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3137 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3138 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3139
3140 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3141 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3142
3143 if (VerifyRememberedSets) {
3144 log_info(gc, verify)("[Verifying RemSets after GC]");
3145 VerifyRegionRemSetClosure v_cl;
3146 heap_region_iterate(&v_cl);
3147 }
3148
3149 _verifier->verify_after_gc();
3150 _verifier->check_bitmaps("GC End");
3151
3152 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3153 ref_processor_stw()->verify_no_references_recorded();
3154
3155 // CM reference discovery will be re-enabled if necessary.
3156 }
3157
3158 #ifdef TRACESPINNING
3159 ParallelTaskTerminator::print_termination_counts();
3160 #endif
3161
3162 gc_epilogue(false);
3163 }
3164
3165 // Print the remainder of the GC log output.
3166 if (evacuation_failed()) {
3167 log_info(gc)("To-space exhausted");
3168 }
3169
3170 g1_policy()->print_phases();
3171 heap_transition.print();
3172
3173 // It is not yet to safe to tell the concurrent mark to
3174 // start as we have some optional output below. We don't want the
3175 // output from the concurrent mark thread interfering with this
3176 // logging output either.
3177
3178 _hrm.verify_optional();
3179 _verifier->verify_region_sets_optional();
3180
3181 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3182 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3183
3184 print_heap_after_gc();
3185 print_heap_regions();
3186 trace_heap_after_gc(_gc_tracer_stw);
3187
3188 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3189 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3190 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3191 // before any GC notifications are raised.
3192 g1mm()->update_sizes();
3193
3194 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3195 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3196 _gc_timer_stw->register_gc_end();
3197 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3198 }
3199 // It should now be safe to tell the concurrent mark thread to start
3200 // without its logging output interfering with the logging output
3201 // that came from the pause.
3202
3203 if (should_start_conc_mark) {
3204 // CAUTION: after the doConcurrentMark() call below,
3205 // the concurrent marking thread(s) could be running
3206 // concurrently with us. Make sure that anything after
3207 // this point does not assume that we are the only GC thread
3208 // running. Note: of course, the actual marking work will
3209 // not start until the safepoint itself is released in
3210 // SuspendibleThreadSet::desynchronize().
3211 doConcurrentMark();
3212 }
3213
3214 return true;
3215 }
3216
3217 void G1CollectedHeap::remove_self_forwarding_pointers() {
3218 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3219 workers()->run_task(&rsfp_task);
3220 }
3221
3222 void G1CollectedHeap::restore_after_evac_failure() {
3223 double remove_self_forwards_start = os::elapsedTime();
3224
3225 remove_self_forwarding_pointers();
3226 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3227 _preserved_marks_set.restore(&task_executor);
3228
3229 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3230 }
3231
3232 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3233 if (!_evacuation_failed) {
3234 _evacuation_failed = true;
3235 }
3236
3237 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3238 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3239 }
3240
3241 bool G1ParEvacuateFollowersClosure::offer_termination() {
3242 G1ParScanThreadState* const pss = par_scan_state();
3243 start_term_time();
3244 const bool res = terminator()->offer_termination();
3245 end_term_time();
3246 return res;
3247 }
3248
3249 void G1ParEvacuateFollowersClosure::do_void() {
3250 G1ParScanThreadState* const pss = par_scan_state();
3251 pss->trim_queue();
3252 do {
3253 pss->steal_and_trim_queue(queues());
3254 } while (!offer_termination());
3255 }
3256
3257 class G1ParTask : public AbstractGangTask {
3258 protected:
3259 G1CollectedHeap* _g1h;
3260 G1ParScanThreadStateSet* _pss;
3261 RefToScanQueueSet* _queues;
3262 G1RootProcessor* _root_processor;
3263 ParallelTaskTerminator _terminator;
3264 uint _n_workers;
3265
3266 public:
3267 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3268 : AbstractGangTask("G1 collection"),
3269 _g1h(g1h),
3270 _pss(per_thread_states),
3271 _queues(task_queues),
3272 _root_processor(root_processor),
3273 _terminator(n_workers, _queues),
3274 _n_workers(n_workers)
3275 {}
3276
3277 void work(uint worker_id) {
3278 if (worker_id >= _n_workers) return; // no work needed this round
3279
3280 double start_sec = os::elapsedTime();
3281 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3282
3283 {
3284 ResourceMark rm;
3285 HandleMark hm;
3286
3287 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3288
3289 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3290 pss->set_ref_processor(rp);
3291
3292 double start_strong_roots_sec = os::elapsedTime();
3293
3294 _root_processor->evacuate_roots(pss->closures(), worker_id);
3295
3296 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3297 // treating the nmethods visited to act as roots for concurrent marking.
3298 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3299 // objects copied by the current evacuation.
3300 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3301 pss->closures()->weak_codeblobs(),
3302 worker_id);
3303
3304 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3305
3306 double term_sec = 0.0;
3307 size_t evac_term_attempts = 0;
3308 {
3309 double start = os::elapsedTime();
3310 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3311 evac.do_void();
3312
3313 evac_term_attempts = evac.term_attempts();
3314 term_sec = evac.term_time();
3315 double elapsed_sec = os::elapsedTime() - start;
3316 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3317 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3318 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3319 }
3320
3321 assert(pss->queue_is_empty(), "should be empty");
3322
3323 if (log_is_enabled(Debug, gc, task, stats)) {
3324 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3325 size_t lab_waste;
3326 size_t lab_undo_waste;
3327 pss->waste(lab_waste, lab_undo_waste);
3328 _g1h->print_termination_stats(worker_id,
3329 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3330 strong_roots_sec * 1000.0, /* strong roots time */
3331 term_sec * 1000.0, /* evac term time */
3332 evac_term_attempts, /* evac term attempts */
3333 lab_waste, /* alloc buffer waste */
3334 lab_undo_waste /* undo waste */
3335 );
3336 }
3337
3338 // Close the inner scope so that the ResourceMark and HandleMark
3339 // destructors are executed here and are included as part of the
3340 // "GC Worker Time".
3341 }
3342 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3343 }
3344 };
3345
3346 void G1CollectedHeap::print_termination_stats_hdr() {
3347 log_debug(gc, task, stats)("GC Termination Stats");
3348 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3349 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3350 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3351 }
3352
3353 void G1CollectedHeap::print_termination_stats(uint worker_id,
3354 double elapsed_ms,
3355 double strong_roots_ms,
3356 double term_ms,
3357 size_t term_attempts,
3358 size_t alloc_buffer_waste,
3359 size_t undo_waste) const {
3360 log_debug(gc, task, stats)
3361 ("%3d %9.2f %9.2f %6.2f "
3362 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3363 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3364 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3365 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3366 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3367 alloc_buffer_waste * HeapWordSize / K,
3368 undo_waste * HeapWordSize / K);
3369 }
3370
3371 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3372 private:
3373 BoolObjectClosure* _is_alive;
3374 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3375
3376 int _initial_string_table_size;
3377 int _initial_symbol_table_size;
3378
3379 bool _process_strings;
3380 int _strings_processed;
3381 int _strings_removed;
3382
3383 bool _process_symbols;
3384 int _symbols_processed;
3385 int _symbols_removed;
3386
3387 bool _process_string_dedup;
3388
3389 public:
3390 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3391 AbstractGangTask("String/Symbol Unlinking"),
3392 _is_alive(is_alive),
3393 _dedup_closure(is_alive, NULL, false),
3394 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3395 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3396 _process_string_dedup(process_string_dedup) {
3397
3398 _initial_string_table_size = StringTable::the_table()->table_size();
3399 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3400 if (process_strings) {
3401 StringTable::clear_parallel_claimed_index();
3402 }
3403 if (process_symbols) {
3404 SymbolTable::clear_parallel_claimed_index();
3405 }
3406 }
3407
3408 ~G1StringAndSymbolCleaningTask() {
3409 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3410 "claim value %d after unlink less than initial string table size %d",
3411 StringTable::parallel_claimed_index(), _initial_string_table_size);
3412 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3413 "claim value %d after unlink less than initial symbol table size %d",
3414 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3415
3416 log_info(gc, stringtable)(
3417 "Cleaned string and symbol table, "
3418 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3419 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3420 strings_processed(), strings_removed(),
3421 symbols_processed(), symbols_removed());
3422 }
3423
3424 void work(uint worker_id) {
3425 int strings_processed = 0;
3426 int strings_removed = 0;
3427 int symbols_processed = 0;
3428 int symbols_removed = 0;
3429 if (_process_strings) {
3430 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3431 Atomic::add(strings_processed, &_strings_processed);
3432 Atomic::add(strings_removed, &_strings_removed);
3433 }
3434 if (_process_symbols) {
3435 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3436 Atomic::add(symbols_processed, &_symbols_processed);
3437 Atomic::add(symbols_removed, &_symbols_removed);
3438 }
3439 if (_process_string_dedup) {
3440 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3441 }
3442 }
3443
3444 size_t strings_processed() const { return (size_t)_strings_processed; }
3445 size_t strings_removed() const { return (size_t)_strings_removed; }
3446
3447 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3448 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3449 };
3450
3451 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3452 private:
3453 static Monitor* _lock;
3454
3455 BoolObjectClosure* const _is_alive;
3456 const bool _unloading_occurred;
3457 const uint _num_workers;
3458
3459 // Variables used to claim nmethods.
3460 CompiledMethod* _first_nmethod;
3461 volatile CompiledMethod* _claimed_nmethod;
3462
3463 // The list of nmethods that need to be processed by the second pass.
3464 volatile CompiledMethod* _postponed_list;
3465 volatile uint _num_entered_barrier;
3466
3467 public:
3468 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3469 _is_alive(is_alive),
3470 _unloading_occurred(unloading_occurred),
3471 _num_workers(num_workers),
3472 _first_nmethod(NULL),
3473 _claimed_nmethod(NULL),
3474 _postponed_list(NULL),
3475 _num_entered_barrier(0)
3476 {
3477 CompiledMethod::increase_unloading_clock();
3478 // Get first alive nmethod
3479 CompiledMethodIterator iter = CompiledMethodIterator();
3480 if(iter.next_alive()) {
3481 _first_nmethod = iter.method();
3482 }
3483 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3484 }
3485
3486 ~G1CodeCacheUnloadingTask() {
3487 CodeCache::verify_clean_inline_caches();
3488
3489 CodeCache::set_needs_cache_clean(false);
3490 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3491
3492 CodeCache::verify_icholder_relocations();
3493 }
3494
3495 private:
3496 void add_to_postponed_list(CompiledMethod* nm) {
3497 CompiledMethod* old;
3498 do {
3499 old = (CompiledMethod*)_postponed_list;
3500 nm->set_unloading_next(old);
3501 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3502 }
3503
3504 void clean_nmethod(CompiledMethod* nm) {
3505 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3506
3507 if (postponed) {
3508 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3509 add_to_postponed_list(nm);
3510 }
3511
3512 // Mark that this thread has been cleaned/unloaded.
3513 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3514 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3515 }
3516
3517 void clean_nmethod_postponed(CompiledMethod* nm) {
3518 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3519 }
3520
3521 static const int MaxClaimNmethods = 16;
3522
3523 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3524 CompiledMethod* first;
3525 CompiledMethodIterator last;
3526
3527 do {
3528 *num_claimed_nmethods = 0;
3529
3530 first = (CompiledMethod*)_claimed_nmethod;
3531 last = CompiledMethodIterator(first);
3532
3533 if (first != NULL) {
3534
3535 for (int i = 0; i < MaxClaimNmethods; i++) {
3536 if (!last.next_alive()) {
3537 break;
3538 }
3539 claimed_nmethods[i] = last.method();
3540 (*num_claimed_nmethods)++;
3541 }
3542 }
3543
3544 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3545 }
3546
3547 CompiledMethod* claim_postponed_nmethod() {
3548 CompiledMethod* claim;
3549 CompiledMethod* next;
3550
3551 do {
3552 claim = (CompiledMethod*)_postponed_list;
3553 if (claim == NULL) {
3554 return NULL;
3555 }
3556
3557 next = claim->unloading_next();
3558
3559 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3560
3561 return claim;
3562 }
3563
3564 public:
3565 // Mark that we're done with the first pass of nmethod cleaning.
3566 void barrier_mark(uint worker_id) {
3567 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3568 _num_entered_barrier++;
3569 if (_num_entered_barrier == _num_workers) {
3570 ml.notify_all();
3571 }
3572 }
3573
3574 // See if we have to wait for the other workers to
3575 // finish their first-pass nmethod cleaning work.
3576 void barrier_wait(uint worker_id) {
3577 if (_num_entered_barrier < _num_workers) {
3578 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3579 while (_num_entered_barrier < _num_workers) {
3580 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3581 }
3582 }
3583 }
3584
3585 // Cleaning and unloading of nmethods. Some work has to be postponed
3586 // to the second pass, when we know which nmethods survive.
3587 void work_first_pass(uint worker_id) {
3588 // The first nmethods is claimed by the first worker.
3589 if (worker_id == 0 && _first_nmethod != NULL) {
3590 clean_nmethod(_first_nmethod);
3591 _first_nmethod = NULL;
3592 }
3593
3594 int num_claimed_nmethods;
3595 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3596
3597 while (true) {
3598 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3599
3600 if (num_claimed_nmethods == 0) {
3601 break;
3602 }
3603
3604 for (int i = 0; i < num_claimed_nmethods; i++) {
3605 clean_nmethod(claimed_nmethods[i]);
3606 }
3607 }
3608 }
3609
3610 void work_second_pass(uint worker_id) {
3611 CompiledMethod* nm;
3612 // Take care of postponed nmethods.
3613 while ((nm = claim_postponed_nmethod()) != NULL) {
3614 clean_nmethod_postponed(nm);
3615 }
3616 }
3617 };
3618
3619 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3620
3621 class G1KlassCleaningTask : public StackObj {
3622 BoolObjectClosure* _is_alive;
3623 volatile jint _clean_klass_tree_claimed;
3624 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3625
3626 public:
3627 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3628 _is_alive(is_alive),
3629 _clean_klass_tree_claimed(0),
3630 _klass_iterator() {
3631 }
3632
3633 private:
3634 bool claim_clean_klass_tree_task() {
3635 if (_clean_klass_tree_claimed) {
3636 return false;
3637 }
3638
3639 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3640 }
3641
3642 InstanceKlass* claim_next_klass() {
3643 Klass* klass;
3644 do {
3645 klass =_klass_iterator.next_klass();
3646 } while (klass != NULL && !klass->is_instance_klass());
3647
3648 // this can be null so don't call InstanceKlass::cast
3649 return static_cast<InstanceKlass*>(klass);
3650 }
3651
3652 public:
3653
3654 void clean_klass(InstanceKlass* ik) {
3655 ik->clean_weak_instanceklass_links(_is_alive);
3656 }
3657
3658 void work() {
3659 ResourceMark rm;
3660
3661 // One worker will clean the subklass/sibling klass tree.
3662 if (claim_clean_klass_tree_task()) {
3663 Klass::clean_subklass_tree(_is_alive);
3664 }
3665
3666 // All workers will help cleaning the classes,
3667 InstanceKlass* klass;
3668 while ((klass = claim_next_klass()) != NULL) {
3669 clean_klass(klass);
3670 }
3671 }
3672 };
3673
3674 class G1ResolvedMethodCleaningTask : public StackObj {
3675 BoolObjectClosure* _is_alive;
3676 volatile jint _resolved_method_task_claimed;
3677 public:
3678 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3679 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3680
3681 bool claim_resolved_method_task() {
3682 if (_resolved_method_task_claimed) {
3683 return false;
3684 }
3685 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3686 }
3687
3688 // These aren't big, one thread can do it all.
3689 void work() {
3690 if (claim_resolved_method_task()) {
3691 ResolvedMethodTable::unlink(_is_alive);
3692 }
3693 }
3694 };
3695
3696
3697 // To minimize the remark pause times, the tasks below are done in parallel.
3698 class G1ParallelCleaningTask : public AbstractGangTask {
3699 private:
3700 G1StringAndSymbolCleaningTask _string_symbol_task;
3701 G1CodeCacheUnloadingTask _code_cache_task;
3702 G1KlassCleaningTask _klass_cleaning_task;
3703 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3704
3705 public:
3706 // The constructor is run in the VMThread.
3707 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3708 AbstractGangTask("Parallel Cleaning"),
3709 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3710 _code_cache_task(num_workers, is_alive, unloading_occurred),
3711 _klass_cleaning_task(is_alive),
3712 _resolved_method_cleaning_task(is_alive) {
3713 }
3714
3715 // The parallel work done by all worker threads.
3716 void work(uint worker_id) {
3717 // Do first pass of code cache cleaning.
3718 _code_cache_task.work_first_pass(worker_id);
3719
3720 // Let the threads mark that the first pass is done.
3721 _code_cache_task.barrier_mark(worker_id);
3722
3723 // Clean the Strings and Symbols.
3724 _string_symbol_task.work(worker_id);
3725
3726 // Clean unreferenced things in the ResolvedMethodTable
3727 _resolved_method_cleaning_task.work();
3728
3729 // Wait for all workers to finish the first code cache cleaning pass.
3730 _code_cache_task.barrier_wait(worker_id);
3731
3732 // Do the second code cache cleaning work, which realize on
3733 // the liveness information gathered during the first pass.
3734 _code_cache_task.work_second_pass(worker_id);
3735
3736 // Clean all klasses that were not unloaded.
3737 _klass_cleaning_task.work();
3738 }
3739 };
3740
3741
3742 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3743 bool class_unloading_occurred) {
3744 uint n_workers = workers()->active_workers();
3745
3746 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3747 workers()->run_task(&g1_unlink_task);
3748 }
3749
3750 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3751 bool process_strings,
3752 bool process_symbols,
3753 bool process_string_dedup) {
3754 if (!process_strings && !process_symbols && !process_string_dedup) {
3755 // Nothing to clean.
3756 return;
3757 }
3758
3759 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3760 workers()->run_task(&g1_unlink_task);
3761
3762 }
3763
3764 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3765 private:
3766 DirtyCardQueueSet* _queue;
3767 G1CollectedHeap* _g1h;
3768 public:
3769 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3770 _queue(queue), _g1h(g1h) { }
3771
3772 virtual void work(uint worker_id) {
3773 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3774 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3775
3776 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3777 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3778
3779 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3780 }
3781 };
3782
3783 void G1CollectedHeap::redirty_logged_cards() {
3784 double redirty_logged_cards_start = os::elapsedTime();
3785
3786 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3787 dirty_card_queue_set().reset_for_par_iteration();
3788 workers()->run_task(&redirty_task);
3789
3790 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3791 dcq.merge_bufferlists(&dirty_card_queue_set());
3792 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3793
3794 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3795 }
3796
3797 // Weak Reference Processing support
3798
3799 // An always "is_alive" closure that is used to preserve referents.
3800 // If the object is non-null then it's alive. Used in the preservation
3801 // of referent objects that are pointed to by reference objects
3802 // discovered by the CM ref processor.
3803 class G1AlwaysAliveClosure: public BoolObjectClosure {
3804 G1CollectedHeap* _g1;
3805 public:
3806 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3807 bool do_object_b(oop p) {
3808 if (p != NULL) {
3809 return true;
3810 }
3811 return false;
3812 }
3813 };
3814
3815 bool G1STWIsAliveClosure::do_object_b(oop p) {
3816 // An object is reachable if it is outside the collection set,
3817 // or is inside and copied.
3818 return !_g1->is_in_cset(p) || p->is_forwarded();
3819 }
3820
3821 // Non Copying Keep Alive closure
3822 class G1KeepAliveClosure: public OopClosure {
3823 G1CollectedHeap* _g1;
3824 public:
3825 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3826 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3827 void do_oop(oop* p) {
3828 oop obj = *p;
3829 assert(obj != NULL, "the caller should have filtered out NULL values");
3830
3831 const InCSetState cset_state = _g1->in_cset_state(obj);
3832 if (!cset_state.is_in_cset_or_humongous()) {
3833 return;
3834 }
3835 if (cset_state.is_in_cset()) {
3836 assert( obj->is_forwarded(), "invariant" );
3837 *p = obj->forwardee();
3838 } else {
3839 assert(!obj->is_forwarded(), "invariant" );
3840 assert(cset_state.is_humongous(),
3841 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3842 _g1->set_humongous_is_live(obj);
3843 }
3844 }
3845 };
3846
3847 // Copying Keep Alive closure - can be called from both
3848 // serial and parallel code as long as different worker
3849 // threads utilize different G1ParScanThreadState instances
3850 // and different queues.
3851
3852 class G1CopyingKeepAliveClosure: public OopClosure {
3853 G1CollectedHeap* _g1h;
3854 OopClosure* _copy_non_heap_obj_cl;
3855 G1ParScanThreadState* _par_scan_state;
3856
3857 public:
3858 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3859 OopClosure* non_heap_obj_cl,
3860 G1ParScanThreadState* pss):
3861 _g1h(g1h),
3862 _copy_non_heap_obj_cl(non_heap_obj_cl),
3863 _par_scan_state(pss)
3864 {}
3865
3866 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3867 virtual void do_oop( oop* p) { do_oop_work(p); }
3868
3869 template <class T> void do_oop_work(T* p) {
3870 oop obj = oopDesc::load_decode_heap_oop(p);
3871
3872 if (_g1h->is_in_cset_or_humongous(obj)) {
3873 // If the referent object has been forwarded (either copied
3874 // to a new location or to itself in the event of an
3875 // evacuation failure) then we need to update the reference
3876 // field and, if both reference and referent are in the G1
3877 // heap, update the RSet for the referent.
3878 //
3879 // If the referent has not been forwarded then we have to keep
3880 // it alive by policy. Therefore we have copy the referent.
3881 //
3882 // If the reference field is in the G1 heap then we can push
3883 // on the PSS queue. When the queue is drained (after each
3884 // phase of reference processing) the object and it's followers
3885 // will be copied, the reference field set to point to the
3886 // new location, and the RSet updated. Otherwise we need to
3887 // use the the non-heap or metadata closures directly to copy
3888 // the referent object and update the pointer, while avoiding
3889 // updating the RSet.
3890
3891 if (_g1h->is_in_g1_reserved(p)) {
3892 _par_scan_state->push_on_queue(p);
3893 } else {
3894 assert(!Metaspace::contains((const void*)p),
3895 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
3896 _copy_non_heap_obj_cl->do_oop(p);
3897 }
3898 }
3899 }
3900 };
3901
3902 // Serial drain queue closure. Called as the 'complete_gc'
3903 // closure for each discovered list in some of the
3904 // reference processing phases.
3905
3906 class G1STWDrainQueueClosure: public VoidClosure {
3907 protected:
3908 G1CollectedHeap* _g1h;
3909 G1ParScanThreadState* _par_scan_state;
3910
3911 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3912
3913 public:
3914 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3915 _g1h(g1h),
3916 _par_scan_state(pss)
3917 { }
3918
3919 void do_void() {
3920 G1ParScanThreadState* const pss = par_scan_state();
3921 pss->trim_queue();
3922 }
3923 };
3924
3925 // Parallel Reference Processing closures
3926
3927 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3928 // processing during G1 evacuation pauses.
3929
3930 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3931 private:
3932 G1CollectedHeap* _g1h;
3933 G1ParScanThreadStateSet* _pss;
3934 RefToScanQueueSet* _queues;
3935 WorkGang* _workers;
3936 uint _active_workers;
3937
3938 public:
3939 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3940 G1ParScanThreadStateSet* per_thread_states,
3941 WorkGang* workers,
3942 RefToScanQueueSet *task_queues,
3943 uint n_workers) :
3944 _g1h(g1h),
3945 _pss(per_thread_states),
3946 _queues(task_queues),
3947 _workers(workers),
3948 _active_workers(n_workers)
3949 {
3950 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
3951 }
3952
3953 // Executes the given task using concurrent marking worker threads.
3954 virtual void execute(ProcessTask& task);
3955 virtual void execute(EnqueueTask& task);
3956 };
3957
3958 // Gang task for possibly parallel reference processing
3959
3960 class G1STWRefProcTaskProxy: public AbstractGangTask {
3961 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3962 ProcessTask& _proc_task;
3963 G1CollectedHeap* _g1h;
3964 G1ParScanThreadStateSet* _pss;
3965 RefToScanQueueSet* _task_queues;
3966 ParallelTaskTerminator* _terminator;
3967
3968 public:
3969 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3970 G1CollectedHeap* g1h,
3971 G1ParScanThreadStateSet* per_thread_states,
3972 RefToScanQueueSet *task_queues,
3973 ParallelTaskTerminator* terminator) :
3974 AbstractGangTask("Process reference objects in parallel"),
3975 _proc_task(proc_task),
3976 _g1h(g1h),
3977 _pss(per_thread_states),
3978 _task_queues(task_queues),
3979 _terminator(terminator)
3980 {}
3981
3982 virtual void work(uint worker_id) {
3983 // The reference processing task executed by a single worker.
3984 ResourceMark rm;
3985 HandleMark hm;
3986
3987 G1STWIsAliveClosure is_alive(_g1h);
3988
3989 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3990 pss->set_ref_processor(NULL);
3991
3992 // Keep alive closure.
3993 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
3994
3995 // Complete GC closure
3996 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3997
3998 // Call the reference processing task's work routine.
3999 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4000
4001 // Note we cannot assert that the refs array is empty here as not all
4002 // of the processing tasks (specifically phase2 - pp2_work) execute
4003 // the complete_gc closure (which ordinarily would drain the queue) so
4004 // the queue may not be empty.
4005 }
4006 };
4007
4008 // Driver routine for parallel reference processing.
4009 // Creates an instance of the ref processing gang
4010 // task and has the worker threads execute it.
4011 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4012 assert(_workers != NULL, "Need parallel worker threads.");
4013
4014 ParallelTaskTerminator terminator(_active_workers, _queues);
4015 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4016
4017 _workers->run_task(&proc_task_proxy);
4018 }
4019
4020 // Gang task for parallel reference enqueueing.
4021
4022 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4023 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4024 EnqueueTask& _enq_task;
4025
4026 public:
4027 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4028 AbstractGangTask("Enqueue reference objects in parallel"),
4029 _enq_task(enq_task)
4030 { }
4031
4032 virtual void work(uint worker_id) {
4033 _enq_task.work(worker_id);
4034 }
4035 };
4036
4037 // Driver routine for parallel reference enqueueing.
4038 // Creates an instance of the ref enqueueing gang
4039 // task and has the worker threads execute it.
4040
4041 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4042 assert(_workers != NULL, "Need parallel worker threads.");
4043
4044 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4045
4046 _workers->run_task(&enq_task_proxy);
4047 }
4048
4049 // End of weak reference support closures
4050
4051 // Abstract task used to preserve (i.e. copy) any referent objects
4052 // that are in the collection set and are pointed to by reference
4053 // objects discovered by the CM ref processor.
4054
4055 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4056 protected:
4057 G1CollectedHeap* _g1h;
4058 G1ParScanThreadStateSet* _pss;
4059 RefToScanQueueSet* _queues;
4060 ParallelTaskTerminator _terminator;
4061 uint _n_workers;
4062
4063 public:
4064 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4065 AbstractGangTask("ParPreserveCMReferents"),
4066 _g1h(g1h),
4067 _pss(per_thread_states),
4068 _queues(task_queues),
4069 _terminator(workers, _queues),
4070 _n_workers(workers)
4071 {
4072 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4073 }
4074
4075 void work(uint worker_id) {
4076 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4077
4078 ResourceMark rm;
4079 HandleMark hm;
4080
4081 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4082 pss->set_ref_processor(NULL);
4083 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4084
4085 // Is alive closure
4086 G1AlwaysAliveClosure always_alive(_g1h);
4087
4088 // Copying keep alive closure. Applied to referent objects that need
4089 // to be copied.
4090 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4091
4092 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4093
4094 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4095 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4096
4097 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4098 // So this must be true - but assert just in case someone decides to
4099 // change the worker ids.
4100 assert(worker_id < limit, "sanity");
4101 assert(!rp->discovery_is_atomic(), "check this code");
4102
4103 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4104 for (uint idx = worker_id; idx < limit; idx += stride) {
4105 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4106
4107 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4108 while (iter.has_next()) {
4109 // Since discovery is not atomic for the CM ref processor, we
4110 // can see some null referent objects.
4111 iter.load_ptrs(DEBUG_ONLY(true));
4112 oop ref = iter.obj();
4113
4114 // This will filter nulls.
4115 if (iter.is_referent_alive()) {
4116 iter.make_referent_alive();
4117 }
4118 iter.move_to_next();
4119 }
4120 }
4121
4122 // Drain the queue - which may cause stealing
4123 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4124 drain_queue.do_void();
4125 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4126 assert(pss->queue_is_empty(), "should be");
4127 }
4128 };
4129
4130 void G1CollectedHeap::process_weak_jni_handles() {
4131 double ref_proc_start = os::elapsedTime();
4132
4133 G1STWIsAliveClosure is_alive(this);
4134 G1KeepAliveClosure keep_alive(this);
4135 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4136
4137 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4138 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4139 }
4140
4141 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4142 // Any reference objects, in the collection set, that were 'discovered'
4143 // by the CM ref processor should have already been copied (either by
4144 // applying the external root copy closure to the discovered lists, or
4145 // by following an RSet entry).
4146 //
4147 // But some of the referents, that are in the collection set, that these
4148 // reference objects point to may not have been copied: the STW ref
4149 // processor would have seen that the reference object had already
4150 // been 'discovered' and would have skipped discovering the reference,
4151 // but would not have treated the reference object as a regular oop.
4152 // As a result the copy closure would not have been applied to the
4153 // referent object.
4154 //
4155 // We need to explicitly copy these referent objects - the references
4156 // will be processed at the end of remarking.
4157 //
4158 // We also need to do this copying before we process the reference
4159 // objects discovered by the STW ref processor in case one of these
4160 // referents points to another object which is also referenced by an
4161 // object discovered by the STW ref processor.
4162 double preserve_cm_referents_time = 0.0;
4163
4164 // To avoid spawning task when there is no work to do, check that
4165 // a concurrent cycle is active and that some references have been
4166 // discovered.
4167 if (concurrent_mark()->cmThread()->during_cycle() &&
4168 ref_processor_cm()->has_discovered_references()) {
4169 double preserve_cm_referents_start = os::elapsedTime();
4170 uint no_of_gc_workers = workers()->active_workers();
4171 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4172 per_thread_states,
4173 no_of_gc_workers,
4174 _task_queues);
4175 workers()->run_task(&keep_cm_referents);
4176 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4177 }
4178
4179 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4180 }
4181
4182 // Weak Reference processing during an evacuation pause (part 1).
4183 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4184 double ref_proc_start = os::elapsedTime();
4185
4186 ReferenceProcessor* rp = _ref_processor_stw;
4187 assert(rp->discovery_enabled(), "should have been enabled");
4188
4189 // Closure to test whether a referent is alive.
4190 G1STWIsAliveClosure is_alive(this);
4191
4192 // Even when parallel reference processing is enabled, the processing
4193 // of JNI refs is serial and performed serially by the current thread
4194 // rather than by a worker. The following PSS will be used for processing
4195 // JNI refs.
4196
4197 // Use only a single queue for this PSS.
4198 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4199 pss->set_ref_processor(NULL);
4200 assert(pss->queue_is_empty(), "pre-condition");
4201
4202 // Keep alive closure.
4203 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4204
4205 // Serial Complete GC closure
4206 G1STWDrainQueueClosure drain_queue(this, pss);
4207
4208 // Setup the soft refs policy...
4209 rp->setup_policy(false);
4210
4211 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4212
4213 ReferenceProcessorStats stats;
4214 if (!rp->processing_is_mt()) {
4215 // Serial reference processing...
4216 stats = rp->process_discovered_references(&is_alive,
4217 &keep_alive,
4218 &drain_queue,
4219 NULL,
4220 pt);
4221 } else {
4222 uint no_of_gc_workers = workers()->active_workers();
4223
4224 // Parallel reference processing
4225 assert(no_of_gc_workers <= rp->max_num_q(),
4226 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4227 no_of_gc_workers, rp->max_num_q());
4228
4229 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4230 stats = rp->process_discovered_references(&is_alive,
4231 &keep_alive,
4232 &drain_queue,
4233 &par_task_executor,
4234 pt);
4235 }
4236
4237 _gc_tracer_stw->report_gc_reference_stats(stats);
4238
4239 // We have completed copying any necessary live referent objects.
4240 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4241
4242 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4243 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4244 }
4245
4246 // Weak Reference processing during an evacuation pause (part 2).
4247 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4248 double ref_enq_start = os::elapsedTime();
4249
4250 ReferenceProcessor* rp = _ref_processor_stw;
4251 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4252
4253 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4254
4255 // Now enqueue any remaining on the discovered lists on to
4256 // the pending list.
4257 if (!rp->processing_is_mt()) {
4258 // Serial reference processing...
4259 rp->enqueue_discovered_references(NULL, pt);
4260 } else {
4261 // Parallel reference enqueueing
4262
4263 uint n_workers = workers()->active_workers();
4264
4265 assert(n_workers <= rp->max_num_q(),
4266 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4267 n_workers, rp->max_num_q());
4268
4269 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4270 rp->enqueue_discovered_references(&par_task_executor, pt);
4271 }
4272
4273 rp->verify_no_references_recorded();
4274 assert(!rp->discovery_enabled(), "should have been disabled");
4275
4276 // If during an initial mark pause we install a pending list head which is not otherwise reachable
4277 // ensure that it is marked in the bitmap for concurrent marking to discover.
4278 if (collector_state()->during_initial_mark_pause()) {
4279 oop pll_head = Universe::reference_pending_list();
4280 if (pll_head != NULL) {
4281 _cm->mark_in_next_bitmap(pll_head);
4282 }
4283 }
4284
4285 // FIXME
4286 // CM's reference processing also cleans up the string and symbol tables.
4287 // Should we do that here also? We could, but it is a serial operation
4288 // and could significantly increase the pause time.
4289
4290 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4291 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4292 }
4293
4294 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4295 double merge_pss_time_start = os::elapsedTime();
4296 per_thread_states->flush();
4297 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4298 }
4299
4300 void G1CollectedHeap::pre_evacuate_collection_set() {
4301 _expand_heap_after_alloc_failure = true;
4302 _evacuation_failed = false;
4303
4304 // Disable the hot card cache.
4305 _hot_card_cache->reset_hot_cache_claimed_index();
4306 _hot_card_cache->set_use_cache(false);
4307
4308 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4309 _preserved_marks_set.assert_empty();
4310
4311 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4312
4313 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4314 if (collector_state()->during_initial_mark_pause()) {
4315 double start_clear_claimed_marks = os::elapsedTime();
4316
4317 ClassLoaderDataGraph::clear_claimed_marks();
4318
4319 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4320 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4321 }
4322 }
4323
4324 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4325 // Should G1EvacuationFailureALot be in effect for this GC?
4326 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4327
4328 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4329
4330 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4331
4332 double start_par_time_sec = os::elapsedTime();
4333 double end_par_time_sec;
4334
4335 {
4336 const uint n_workers = workers()->active_workers();
4337 G1RootProcessor root_processor(this, n_workers);
4338 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4339
4340 print_termination_stats_hdr();
4341
4342 workers()->run_task(&g1_par_task);
4343 end_par_time_sec = os::elapsedTime();
4344
4345 // Closing the inner scope will execute the destructor
4346 // for the G1RootProcessor object. We record the current
4347 // elapsed time before closing the scope so that time
4348 // taken for the destructor is NOT included in the
4349 // reported parallel time.
4350 }
4351
4352 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4353 phase_times->record_par_time(par_time_ms);
4354
4355 double code_root_fixup_time_ms =
4356 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4357 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4358 }
4359
4360 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4361 // Process any discovered reference objects - we have
4362 // to do this _before_ we retire the GC alloc regions
4363 // as we may have to copy some 'reachable' referent
4364 // objects (and their reachable sub-graphs) that were
4365 // not copied during the pause.
4366 if (g1_policy()->should_process_references()) {
4367 preserve_cm_referents(per_thread_states);
4368 process_discovered_references(per_thread_states);
4369 } else {
4370 ref_processor_stw()->verify_no_references_recorded();
4371 process_weak_jni_handles();
4372 }
4373
4374 if (G1StringDedup::is_enabled()) {
4375 double fixup_start = os::elapsedTime();
4376
4377 G1STWIsAliveClosure is_alive(this);
4378 G1KeepAliveClosure keep_alive(this);
4379 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4380
4381 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4382 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4383 }
4384
4385 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4386
4387 if (evacuation_failed()) {
4388 restore_after_evac_failure();
4389
4390 // Reset the G1EvacuationFailureALot counters and flags
4391 // Note: the values are reset only when an actual
4392 // evacuation failure occurs.
4393 NOT_PRODUCT(reset_evacuation_should_fail();)
4394 }
4395
4396 _preserved_marks_set.assert_empty();
4397
4398 // Enqueue any remaining references remaining on the STW
4399 // reference processor's discovered lists. We need to do
4400 // this after the card table is cleaned (and verified) as
4401 // the act of enqueueing entries on to the pending list
4402 // will log these updates (and dirty their associated
4403 // cards). We need these updates logged to update any
4404 // RSets.
4405 if (g1_policy()->should_process_references()) {
4406 enqueue_discovered_references(per_thread_states);
4407 } else {
4408 g1_policy()->phase_times()->record_ref_enq_time(0);
4409 }
4410
4411 _allocator->release_gc_alloc_regions(evacuation_info);
4412
4413 merge_per_thread_state_info(per_thread_states);
4414
4415 // Reset and re-enable the hot card cache.
4416 // Note the counts for the cards in the regions in the
4417 // collection set are reset when the collection set is freed.
4418 _hot_card_cache->reset_hot_cache();
4419 _hot_card_cache->set_use_cache(true);
4420
4421 purge_code_root_memory();
4422
4423 redirty_logged_cards();
4424 #if defined(COMPILER2) || INCLUDE_JVMCI
4425 double start = os::elapsedTime();
4426 DerivedPointerTable::update_pointers();
4427 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4428 #endif
4429 g1_policy()->print_age_table();
4430 }
4431
4432 void G1CollectedHeap::record_obj_copy_mem_stats() {
4433 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4434
4435 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4436 create_g1_evac_summary(&_old_evac_stats));
4437 }
4438
4439 void G1CollectedHeap::free_region(HeapRegion* hr,
4440 FreeRegionList* free_list,
4441 bool skip_remset,
4442 bool skip_hot_card_cache,
4443 bool locked) {
4444 assert(!hr->is_free(), "the region should not be free");
4445 assert(!hr->is_empty(), "the region should not be empty");
4446 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4447 assert(free_list != NULL, "pre-condition");
4448
4449 if (G1VerifyBitmaps) {
4450 MemRegion mr(hr->bottom(), hr->end());
4451 concurrent_mark()->clearRangePrevBitmap(mr);
4452 }
4453
4454 // Clear the card counts for this region.
4455 // Note: we only need to do this if the region is not young
4456 // (since we don't refine cards in young regions).
4457 if (!skip_hot_card_cache && !hr->is_young()) {
4458 _hot_card_cache->reset_card_counts(hr);
4459 }
4460 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4461 free_list->add_ordered(hr);
4462 }
4463
4464 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4465 FreeRegionList* free_list,
4466 bool skip_remset) {
4467 assert(hr->is_humongous(), "this is only for humongous regions");
4468 assert(free_list != NULL, "pre-condition");
4469 hr->clear_humongous();
4470 free_region(hr, free_list, skip_remset);
4471 }
4472
4473 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4474 const uint humongous_regions_removed) {
4475 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4476 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4477 _old_set.bulk_remove(old_regions_removed);
4478 _humongous_set.bulk_remove(humongous_regions_removed);
4479 }
4480
4481 }
4482
4483 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4484 assert(list != NULL, "list can't be null");
4485 if (!list->is_empty()) {
4486 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4487 _hrm.insert_list_into_free_list(list);
4488 }
4489 }
4490
4491 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4492 decrease_used(bytes);
4493 }
4494
4495 class G1ParScrubRemSetTask: public AbstractGangTask {
4496 protected:
4497 G1RemSet* _g1rs;
4498 HeapRegionClaimer _hrclaimer;
4499
4500 public:
4501 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4502 AbstractGangTask("G1 ScrubRS"),
4503 _g1rs(g1_rs),
4504 _hrclaimer(num_workers) {
4505 }
4506
4507 void work(uint worker_id) {
4508 _g1rs->scrub(worker_id, &_hrclaimer);
4509 }
4510 };
4511
4512 void G1CollectedHeap::scrub_rem_set() {
4513 uint num_workers = workers()->active_workers();
4514 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4515 workers()->run_task(&g1_par_scrub_rs_task);
4516 }
4517
4518 class G1FreeCollectionSetTask : public AbstractGangTask {
4519 private:
4520
4521 // Closure applied to all regions in the collection set to do work that needs to
4522 // be done serially in a single thread.
4523 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4524 private:
4525 EvacuationInfo* _evacuation_info;
4526 const size_t* _surviving_young_words;
4527
4528 // Bytes used in successfully evacuated regions before the evacuation.
4529 size_t _before_used_bytes;
4530 // Bytes used in unsucessfully evacuated regions before the evacuation
4531 size_t _after_used_bytes;
4532
4533 size_t _bytes_allocated_in_old_since_last_gc;
4534
4535 size_t _failure_used_words;
4536 size_t _failure_waste_words;
4537
4538 FreeRegionList _local_free_list;
4539 public:
4540 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4541 HeapRegionClosure(),
4542 _evacuation_info(evacuation_info),
4543 _surviving_young_words(surviving_young_words),
4544 _before_used_bytes(0),
4545 _after_used_bytes(0),
4546 _bytes_allocated_in_old_since_last_gc(0),
4547 _failure_used_words(0),
4548 _failure_waste_words(0),
4549 _local_free_list("Local Region List for CSet Freeing") {
4550 }
4551
4552 virtual bool doHeapRegion(HeapRegion* r) {
4553 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4554
4555 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4556 g1h->clear_in_cset(r);
4557
4558 if (r->is_young()) {
4559 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4560 "Young index %d is wrong for region %u of type %s with %u young regions",
4561 r->young_index_in_cset(),
4562 r->hrm_index(),
4563 r->get_type_str(),
4564 g1h->collection_set()->young_region_length());
4565 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4566 r->record_surv_words_in_group(words_survived);
4567 }
4568
4569 if (!r->evacuation_failed()) {
4570 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4571 _before_used_bytes += r->used();
4572 g1h->free_region(r,
4573 &_local_free_list,
4574 true, /* skip_remset */
4575 true, /* skip_hot_card_cache */
4576 true /* locked */);
4577 } else {
4578 r->uninstall_surv_rate_group();
4579 r->set_young_index_in_cset(-1);
4580 r->set_evacuation_failed(false);
4581 // When moving a young gen region to old gen, we "allocate" that whole region
4582 // there. This is in addition to any already evacuated objects. Notify the
4583 // policy about that.
4584 // Old gen regions do not cause an additional allocation: both the objects
4585 // still in the region and the ones already moved are accounted for elsewhere.
4586 if (r->is_young()) {
4587 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4588 }
4589 // The region is now considered to be old.
4590 r->set_old();
4591 // Do some allocation statistics accounting. Regions that failed evacuation
4592 // are always made old, so there is no need to update anything in the young
4593 // gen statistics, but we need to update old gen statistics.
4594 size_t used_words = r->marked_bytes() / HeapWordSize;
4595
4596 _failure_used_words += used_words;
4597 _failure_waste_words += HeapRegion::GrainWords - used_words;
4598
4599 g1h->old_set_add(r);
4600 _after_used_bytes += r->used();
4601 }
4602 return false;
4603 }
4604
4605 void complete_work() {
4606 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4607
4608 _evacuation_info->set_regions_freed(_local_free_list.length());
4609 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4610
4611 g1h->prepend_to_freelist(&_local_free_list);
4612 g1h->decrement_summary_bytes(_before_used_bytes);
4613
4614 G1Policy* policy = g1h->g1_policy();
4615 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4616
4617 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4618 }
4619 };
4620
4621 G1CollectionSet* _collection_set;
4622 G1SerialFreeCollectionSetClosure _cl;
4623 const size_t* _surviving_young_words;
4624
4625 size_t _rs_lengths;
4626
4627 volatile jint _serial_work_claim;
4628
4629 struct WorkItem {
4630 uint region_idx;
4631 bool is_young;
4632 bool evacuation_failed;
4633
4634 WorkItem(HeapRegion* r) {
4635 region_idx = r->hrm_index();
4636 is_young = r->is_young();
4637 evacuation_failed = r->evacuation_failed();
4638 }
4639 };
4640
4641 volatile size_t _parallel_work_claim;
4642 size_t _num_work_items;
4643 WorkItem* _work_items;
4644
4645 void do_serial_work() {
4646 // Need to grab the lock to be allowed to modify the old region list.
4647 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4648 _collection_set->iterate(&_cl);
4649 }
4650
4651 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4652 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4653
4654 HeapRegion* r = g1h->region_at(region_idx);
4655 assert(!g1h->is_on_master_free_list(r), "sanity");
4656
4657 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4658
4659 if (!is_young) {
4660 g1h->_hot_card_cache->reset_card_counts(r);
4661 }
4662
4663 if (!evacuation_failed) {
4664 r->rem_set()->clear_locked();
4665 }
4666 }
4667
4668 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4669 private:
4670 size_t _cur_idx;
4671 WorkItem* _work_items;
4672 public:
4673 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4674
4675 virtual bool doHeapRegion(HeapRegion* r) {
4676 _work_items[_cur_idx++] = WorkItem(r);
4677 return false;
4678 }
4679 };
4680
4681 void prepare_work() {
4682 G1PrepareFreeCollectionSetClosure cl(_work_items);
4683 _collection_set->iterate(&cl);
4684 }
4685
4686 void complete_work() {
4687 _cl.complete_work();
4688
4689 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4690 policy->record_max_rs_lengths(_rs_lengths);
4691 policy->cset_regions_freed();
4692 }
4693 public:
4694 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4695 AbstractGangTask("G1 Free Collection Set"),
4696 _cl(evacuation_info, surviving_young_words),
4697 _collection_set(collection_set),
4698 _surviving_young_words(surviving_young_words),
4699 _serial_work_claim(0),
4700 _rs_lengths(0),
4701 _parallel_work_claim(0),
4702 _num_work_items(collection_set->region_length()),
4703 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4704 prepare_work();
4705 }
4706
4707 ~G1FreeCollectionSetTask() {
4708 complete_work();
4709 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4710 }
4711
4712 // Chunk size for work distribution. The chosen value has been determined experimentally
4713 // to be a good tradeoff between overhead and achievable parallelism.
4714 static uint chunk_size() { return 32; }
4715
4716 virtual void work(uint worker_id) {
4717 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4718
4719 // Claim serial work.
4720 if (_serial_work_claim == 0) {
4721 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4722 if (value == 0) {
4723 double serial_time = os::elapsedTime();
4724 do_serial_work();
4725 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4726 }
4727 }
4728
4729 // Start parallel work.
4730 double young_time = 0.0;
4731 bool has_young_time = false;
4732 double non_young_time = 0.0;
4733 bool has_non_young_time = false;
4734
4735 while (true) {
4736 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4737 size_t cur = end - chunk_size();
4738
4739 if (cur >= _num_work_items) {
4740 break;
4741 }
4742
4743 double start_time = os::elapsedTime();
4744
4745 end = MIN2(end, _num_work_items);
4746
4747 for (; cur < end; cur++) {
4748 bool is_young = _work_items[cur].is_young;
4749
4750 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4751
4752 double end_time = os::elapsedTime();
4753 double time_taken = end_time - start_time;
4754 if (is_young) {
4755 young_time += time_taken;
4756 has_young_time = true;
4757 } else {
4758 non_young_time += time_taken;
4759 has_non_young_time = true;
4760 }
4761 start_time = end_time;
4762 }
4763 }
4764
4765 if (has_young_time) {
4766 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4767 }
4768 if (has_non_young_time) {
4769 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4770 }
4771 }
4772 };
4773
4774 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4775 _eden.clear();
4776
4777 double free_cset_start_time = os::elapsedTime();
4778
4779 {
4780 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4781 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4782
4783 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4784
4785 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4786 cl.name(),
4787 num_workers,
4788 _collection_set.region_length());
4789 workers()->run_task(&cl, num_workers);
4790 }
4791 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4792
4793 collection_set->clear();
4794 }
4795
4796 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4797 private:
4798 FreeRegionList* _free_region_list;
4799 HeapRegionSet* _proxy_set;
4800 uint _humongous_objects_reclaimed;
4801 uint _humongous_regions_reclaimed;
4802 size_t _freed_bytes;
4803 public:
4804
4805 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4806 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4807 }
4808
4809 virtual bool doHeapRegion(HeapRegion* r) {
4810 if (!r->is_starts_humongous()) {
4811 return false;
4812 }
4813
4814 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4815
4816 oop obj = (oop)r->bottom();
4817 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4818
4819 // The following checks whether the humongous object is live are sufficient.
4820 // The main additional check (in addition to having a reference from the roots
4821 // or the young gen) is whether the humongous object has a remembered set entry.
4822 //
4823 // A humongous object cannot be live if there is no remembered set for it
4824 // because:
4825 // - there can be no references from within humongous starts regions referencing
4826 // the object because we never allocate other objects into them.
4827 // (I.e. there are no intra-region references that may be missed by the
4828 // remembered set)
4829 // - as soon there is a remembered set entry to the humongous starts region
4830 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4831 // until the end of a concurrent mark.
4832 //
4833 // It is not required to check whether the object has been found dead by marking
4834 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4835 // all objects allocated during that time are considered live.
4836 // SATB marking is even more conservative than the remembered set.
4837 // So if at this point in the collection there is no remembered set entry,
4838 // nobody has a reference to it.
4839 // At the start of collection we flush all refinement logs, and remembered sets
4840 // are completely up-to-date wrt to references to the humongous object.
4841 //
4842 // Other implementation considerations:
4843 // - never consider object arrays at this time because they would pose
4844 // considerable effort for cleaning up the the remembered sets. This is
4845 // required because stale remembered sets might reference locations that
4846 // are currently allocated into.
4847 uint region_idx = r->hrm_index();
4848 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4849 !r->rem_set()->is_empty()) {
4850 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",
4851 region_idx,
4852 (size_t)obj->size() * HeapWordSize,
4853 p2i(r->bottom()),
4854 r->rem_set()->occupied(),
4855 r->rem_set()->strong_code_roots_list_length(),
4856 next_bitmap->is_marked(r->bottom()),
4857 g1h->is_humongous_reclaim_candidate(region_idx),
4858 obj->is_typeArray()
4859 );
4860 return false;
4861 }
4862
4863 guarantee(obj->is_typeArray(),
4864 "Only eagerly reclaiming type arrays is supported, but the object "
4865 PTR_FORMAT " is not.", p2i(r->bottom()));
4866
4867 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",
4868 region_idx,
4869 (size_t)obj->size() * HeapWordSize,
4870 p2i(r->bottom()),
4871 r->rem_set()->occupied(),
4872 r->rem_set()->strong_code_roots_list_length(),
4873 next_bitmap->is_marked(r->bottom()),
4874 g1h->is_humongous_reclaim_candidate(region_idx),
4875 obj->is_typeArray()
4876 );
4877
4878 // Need to clear mark bit of the humongous object if already set.
4879 if (next_bitmap->is_marked(r->bottom())) {
4880 next_bitmap->clear(r->bottom());
4881 }
4882 _humongous_objects_reclaimed++;
4883 do {
4884 HeapRegion* next = g1h->next_region_in_humongous(r);
4885 _freed_bytes += r->used();
4886 r->set_containing_set(NULL);
4887 _humongous_regions_reclaimed++;
4888 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4889 r = next;
4890 } while (r != NULL);
4891
4892 return false;
4893 }
4894
4895 uint humongous_objects_reclaimed() {
4896 return _humongous_objects_reclaimed;
4897 }
4898
4899 uint humongous_regions_reclaimed() {
4900 return _humongous_regions_reclaimed;
4901 }
4902
4903 size_t bytes_freed() const {
4904 return _freed_bytes;
4905 }
4906 };
4907
4908 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4909 assert_at_safepoint(true);
4910
4911 if (!G1EagerReclaimHumongousObjects ||
4912 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4913 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4914 return;
4915 }
4916
4917 double start_time = os::elapsedTime();
4918
4919 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4920
4921 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4922 heap_region_iterate(&cl);
4923
4924 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4925
4926 G1HRPrinter* hrp = hr_printer();
4927 if (hrp->is_active()) {
4928 FreeRegionListIterator iter(&local_cleanup_list);
4929 while (iter.more_available()) {
4930 HeapRegion* hr = iter.get_next();
4931 hrp->cleanup(hr);
4932 }
4933 }
4934
4935 prepend_to_freelist(&local_cleanup_list);
4936 decrement_summary_bytes(cl.bytes_freed());
4937
4938 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4939 cl.humongous_objects_reclaimed());
4940 }
4941
4942 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4943 public:
4944 virtual bool doHeapRegion(HeapRegion* r) {
4945 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4946 G1CollectedHeap::heap()->clear_in_cset(r);
4947 r->set_young_index_in_cset(-1);
4948 return false;
4949 }
4950 };
4951
4952 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4953 G1AbandonCollectionSetClosure cl;
4954 collection_set->iterate(&cl);
4955
4956 collection_set->clear();
4957 collection_set->stop_incremental_building();
4958 }
4959
4960 void G1CollectedHeap::set_free_regions_coming() {
4961 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
4962
4963 assert(!free_regions_coming(), "pre-condition");
4964 _free_regions_coming = true;
4965 }
4966
4967 void G1CollectedHeap::reset_free_regions_coming() {
4968 assert(free_regions_coming(), "pre-condition");
4969
4970 {
4971 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4972 _free_regions_coming = false;
4973 SecondaryFreeList_lock->notify_all();
4974 }
4975
4976 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
4977 }
4978
4979 void G1CollectedHeap::wait_while_free_regions_coming() {
4980 // Most of the time we won't have to wait, so let's do a quick test
4981 // first before we take the lock.
4982 if (!free_regions_coming()) {
4983 return;
4984 }
4985
4986 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
4987
4988 {
4989 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
4990 while (free_regions_coming()) {
4991 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
4992 }
4993 }
4994
4995 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
4996 }
4997
4998 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4999 return _allocator->is_retained_old_region(hr);
5000 }
5001
5002 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5003 _eden.add(hr);
5004 _g1_policy->set_region_eden(hr);
5005 }
5006
5007 #ifdef ASSERT
5008
5009 class NoYoungRegionsClosure: public HeapRegionClosure {
5010 private:
5011 bool _success;
5012 public:
5013 NoYoungRegionsClosure() : _success(true) { }
5014 bool doHeapRegion(HeapRegion* r) {
5015 if (r->is_young()) {
5016 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5017 p2i(r->bottom()), p2i(r->end()));
5018 _success = false;
5019 }
5020 return false;
5021 }
5022 bool success() { return _success; }
5023 };
5024
5025 bool G1CollectedHeap::check_young_list_empty() {
5026 bool ret = (young_regions_count() == 0);
5027
5028 NoYoungRegionsClosure closure;
5029 heap_region_iterate(&closure);
5030 ret = ret && closure.success();
5031
5032 return ret;
5033 }
5034
5035 #endif // ASSERT
5036
5037 class TearDownRegionSetsClosure : public HeapRegionClosure {
5038 private:
5039 HeapRegionSet *_old_set;
5040
5041 public:
5042 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5043
5044 bool doHeapRegion(HeapRegion* r) {
5045 if (r->is_old()) {
5046 _old_set->remove(r);
5047 } else if(r->is_young()) {
5048 r->uninstall_surv_rate_group();
5049 } else {
5050 // We ignore free regions, we'll empty the free list afterwards.
5051 // We ignore humongous regions, we're not tearing down the
5052 // humongous regions set.
5053 assert(r->is_free() || r->is_humongous(),
5054 "it cannot be another type");
5055 }
5056 return false;
5057 }
5058
5059 ~TearDownRegionSetsClosure() {
5060 assert(_old_set->is_empty(), "post-condition");
5061 }
5062 };
5063
5064 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5065 assert_at_safepoint(true /* should_be_vm_thread */);
5066
5067 if (!free_list_only) {
5068 TearDownRegionSetsClosure cl(&_old_set);
5069 heap_region_iterate(&cl);
5070
5071 // Note that emptying the _young_list is postponed and instead done as
5072 // the first step when rebuilding the regions sets again. The reason for
5073 // this is that during a full GC string deduplication needs to know if
5074 // a collected region was young or old when the full GC was initiated.
5075 }
5076 _hrm.remove_all_free_regions();
5077 }
5078
5079 void G1CollectedHeap::increase_used(size_t bytes) {
5080 _summary_bytes_used += bytes;
5081 }
5082
5083 void G1CollectedHeap::decrease_used(size_t bytes) {
5084 assert(_summary_bytes_used >= bytes,
5085 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5086 _summary_bytes_used, bytes);
5087 _summary_bytes_used -= bytes;
5088 }
5089
5090 void G1CollectedHeap::set_used(size_t bytes) {
5091 _summary_bytes_used = bytes;
5092 }
5093
5094 class RebuildRegionSetsClosure : public HeapRegionClosure {
5095 private:
5096 bool _free_list_only;
5097 HeapRegionSet* _old_set;
5098 HeapRegionManager* _hrm;
5099 size_t _total_used;
5100
5101 public:
5102 RebuildRegionSetsClosure(bool free_list_only,
5103 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5104 _free_list_only(free_list_only),
5105 _old_set(old_set), _hrm(hrm), _total_used(0) {
5106 assert(_hrm->num_free_regions() == 0, "pre-condition");
5107 if (!free_list_only) {
5108 assert(_old_set->is_empty(), "pre-condition");
5109 }
5110 }
5111
5112 bool doHeapRegion(HeapRegion* r) {
5113 if (r->is_empty()) {
5114 // Add free regions to the free list
5115 r->set_free();
5116 r->set_allocation_context(AllocationContext::system());
5117 _hrm->insert_into_free_list(r);
5118 } else if (!_free_list_only) {
5119
5120 if (r->is_humongous()) {
5121 // We ignore humongous regions. We left the humongous set unchanged.
5122 } else {
5123 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5124 // We now move all (non-humongous, non-old) regions to old gen, and register them as such.
5125 r->move_to_old();
5126 _old_set->add(r);
5127 }
5128 _total_used += r->used();
5129 }
5130
5131 return false;
5132 }
5133
5134 size_t total_used() {
5135 return _total_used;
5136 }
5137 };
5138
5139 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5140 assert_at_safepoint(true /* should_be_vm_thread */);
5141
5142 if (!free_list_only) {
5143 _eden.clear();
5144 _survivor.clear();
5145 }
5146
5147 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5148 heap_region_iterate(&cl);
5149
5150 if (!free_list_only) {
5151 set_used(cl.total_used());
5152 if (_archive_allocator != NULL) {
5153 _archive_allocator->clear_used();
5154 }
5155 }
5156 assert(used_unlocked() == recalculate_used(),
5157 "inconsistent used_unlocked(), "
5158 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5159 used_unlocked(), recalculate_used());
5160 }
5161
5162 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5163 HeapRegion* hr = heap_region_containing(p);
5164 return hr->is_in(p);
5165 }
5166
5167 // Methods for the mutator alloc region
5168
5169 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5170 bool force) {
5171 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5172 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5173 if (force || should_allocate) {
5174 HeapRegion* new_alloc_region = new_region(word_size,
5175 false /* is_old */,
5176 false /* do_expand */);
5177 if (new_alloc_region != NULL) {
5178 set_region_short_lived_locked(new_alloc_region);
5179 _hr_printer.alloc(new_alloc_region, !should_allocate);
5180 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5181 return new_alloc_region;
5182 }
5183 }
5184 return NULL;
5185 }
5186
5187 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5188 size_t allocated_bytes) {
5189 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5190 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5191
5192 collection_set()->add_eden_region(alloc_region);
5193 increase_used(allocated_bytes);
5194 _hr_printer.retire(alloc_region);
5195 // We update the eden sizes here, when the region is retired,
5196 // instead of when it's allocated, since this is the point that its
5197 // used space has been recored in _summary_bytes_used.
5198 g1mm()->update_eden_size();
5199 }
5200
5201 // Methods for the GC alloc regions
5202
5203 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5204 if (dest.is_old()) {
5205 return true;
5206 } else {
5207 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5208 }
5209 }
5210
5211 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5212 assert(FreeList_lock->owned_by_self(), "pre-condition");
5213
5214 if (!has_more_regions(dest)) {
5215 return NULL;
5216 }
5217
5218 const bool is_survivor = dest.is_young();
5219
5220 HeapRegion* new_alloc_region = new_region(word_size,
5221 !is_survivor,
5222 true /* do_expand */);
5223 if (new_alloc_region != NULL) {
5224 // We really only need to do this for old regions given that we
5225 // should never scan survivors. But it doesn't hurt to do it
5226 // for survivors too.
5227 new_alloc_region->record_timestamp();
5228 if (is_survivor) {
5229 new_alloc_region->set_survivor();
5230 _survivor.add(new_alloc_region);
5231 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5232 } else {
5233 new_alloc_region->set_old();
5234 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5235 }
5236 _hr_printer.alloc(new_alloc_region);
5237 bool during_im = collector_state()->during_initial_mark_pause();
5238 new_alloc_region->note_start_of_copying(during_im);
5239 return new_alloc_region;
5240 }
5241 return NULL;
5242 }
5243
5244 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5245 size_t allocated_bytes,
5246 InCSetState dest) {
5247 bool during_im = collector_state()->during_initial_mark_pause();
5248 alloc_region->note_end_of_copying(during_im);
5249 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5250 if (dest.is_old()) {
5251 _old_set.add(alloc_region);
5252 }
5253 _hr_printer.retire(alloc_region);
5254 }
5255
5256 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5257 bool expanded = false;
5258 uint index = _hrm.find_highest_free(&expanded);
5259
5260 if (index != G1_NO_HRM_INDEX) {
5261 if (expanded) {
5262 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5263 HeapRegion::GrainWords * HeapWordSize);
5264 }
5265 _hrm.allocate_free_regions_starting_at(index, 1);
5266 return region_at(index);
5267 }
5268 return NULL;
5269 }
5270
5271 // Optimized nmethod scanning
5272
5273 class RegisterNMethodOopClosure: public OopClosure {
5274 G1CollectedHeap* _g1h;
5275 nmethod* _nm;
5276
5277 template <class T> void do_oop_work(T* p) {
5278 T heap_oop = oopDesc::load_heap_oop(p);
5279 if (!oopDesc::is_null(heap_oop)) {
5280 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5281 HeapRegion* hr = _g1h->heap_region_containing(obj);
5282 assert(!hr->is_continues_humongous(),
5283 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5284 " starting at " HR_FORMAT,
5285 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5286
5287 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5288 hr->add_strong_code_root_locked(_nm);
5289 }
5290 }
5291
5292 public:
5293 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5294 _g1h(g1h), _nm(nm) {}
5295
5296 void do_oop(oop* p) { do_oop_work(p); }
5297 void do_oop(narrowOop* p) { do_oop_work(p); }
5298 };
5299
5300 class UnregisterNMethodOopClosure: public OopClosure {
5301 G1CollectedHeap* _g1h;
5302 nmethod* _nm;
5303
5304 template <class T> void do_oop_work(T* p) {
5305 T heap_oop = oopDesc::load_heap_oop(p);
5306 if (!oopDesc::is_null(heap_oop)) {
5307 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5308 HeapRegion* hr = _g1h->heap_region_containing(obj);
5309 assert(!hr->is_continues_humongous(),
5310 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5311 " starting at " HR_FORMAT,
5312 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5313
5314 hr->remove_strong_code_root(_nm);
5315 }
5316 }
5317
5318 public:
5319 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5320 _g1h(g1h), _nm(nm) {}
5321
5322 void do_oop(oop* p) { do_oop_work(p); }
5323 void do_oop(narrowOop* p) { do_oop_work(p); }
5324 };
5325
5326 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5327 CollectedHeap::register_nmethod(nm);
5328
5329 guarantee(nm != NULL, "sanity");
5330 RegisterNMethodOopClosure reg_cl(this, nm);
5331 nm->oops_do(®_cl);
5332 }
5333
5334 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5335 CollectedHeap::unregister_nmethod(nm);
5336
5337 guarantee(nm != NULL, "sanity");
5338 UnregisterNMethodOopClosure reg_cl(this, nm);
5339 nm->oops_do(®_cl, true);
5340 }
5341
5342 void G1CollectedHeap::purge_code_root_memory() {
5343 double purge_start = os::elapsedTime();
5344 G1CodeRootSet::purge();
5345 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5346 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5347 }
5348
5349 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5350 G1CollectedHeap* _g1h;
5351
5352 public:
5353 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5354 _g1h(g1h) {}
5355
5356 void do_code_blob(CodeBlob* cb) {
5357 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5358 if (nm == NULL) {
5359 return;
5360 }
5361
5362 if (ScavengeRootsInCode) {
5363 _g1h->register_nmethod(nm);
5364 }
5365 }
5366 };
5367
5368 void G1CollectedHeap::rebuild_strong_code_roots() {
5369 RebuildStrongCodeRootClosure blob_cl(this);
5370 CodeCache::blobs_do(&blob_cl);
5371 }