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