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