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 ReferenceProcessorPhaseTimes pt(NULL, ref_processor_stw()->num_q());
1264
1265 // Enqueue any discovered reference objects that have
1266 // not been removed from the discovered lists.
1267 ref_processor_stw()->enqueue_discovered_references(NULL, &pt);
1268
1269 pt.print_enqueue_phase();
1270
1271 #if defined(COMPILER2) || INCLUDE_JVMCI
1272 DerivedPointerTable::update_pointers();
1273 #endif
1274
1275 MemoryService::track_memory_usage();
1276
1277 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1278 ref_processor_stw()->verify_no_references_recorded();
1279
1280 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1281 ClassLoaderDataGraph::purge();
1282 MetaspaceAux::verify_metrics();
1283
1284 // Note: since we've just done a full GC, concurrent
1285 // marking is no longer active. Therefore we need not
1286 // re-enable reference discovery for the CM ref processor.
1287 // That will be done at the start of the next marking cycle.
1288 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1289 ref_processor_cm()->verify_no_references_recorded();
1290
1291 reset_gc_time_stamp();
1292 // Since everything potentially moved, we will clear all remembered
1293 // sets, and clear all cards. Later we will rebuild remembered
1294 // sets. We will also reset the GC time stamps of the regions.
1295 clear_rsets_post_compaction();
1296 check_gc_time_stamps();
1297
1298 resize_if_necessary_after_full_collection();
1299
1300 // We should do this after we potentially resize the heap so
1301 // that all the COMMIT / UNCOMMIT events are generated before
1302 // the compaction events.
1303 print_hrm_post_compaction();
1304
1305 if (_hot_card_cache->use_cache()) {
1306 _hot_card_cache->reset_card_counts();
1307 _hot_card_cache->reset_hot_cache();
1308 }
1309
1310 // Rebuild remembered sets of all regions.
1311 uint n_workers =
1312 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1313 workers()->active_workers(),
1314 Threads::number_of_non_daemon_threads());
1315 workers()->update_active_workers(n_workers);
1316 log_info(gc,task)("Using %u workers of %u to rebuild remembered set", n_workers, workers()->total_workers());
1317
1318 ParRebuildRSTask rebuild_rs_task(this);
1319 workers()->run_task(&rebuild_rs_task);
1320
1321 // Rebuild the strong code root lists for each region
1322 rebuild_strong_code_roots();
1323
1324 if (true) { // FIXME
1325 MetaspaceGC::compute_new_size();
1326 }
1327
1328 #ifdef TRACESPINNING
1329 ParallelTaskTerminator::print_termination_counts();
1330 #endif
1331
1332 // Discard all rset updates
1333 JavaThread::dirty_card_queue_set().abandon_logs();
1334 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1335
1336 // At this point there should be no regions in the
1337 // entire heap tagged as young.
1338 assert(check_young_list_empty(), "young list should be empty at this point");
1339
1340 // Update the number of full collections that have been completed.
1341 increment_old_marking_cycles_completed(false /* concurrent */);
1342
1343 _hrm.verify_optional();
1344 _verifier->verify_region_sets_optional();
1345
1346 _verifier->verify_after_gc();
1347
1348 // Clear the previous marking bitmap, if needed for bitmap verification.
1349 // Note we cannot do this when we clear the next marking bitmap in
1350 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1351 // objects marked during a full GC against the previous bitmap.
1352 // But we need to clear it before calling check_bitmaps below since
1353 // the full GC has compacted objects and updated TAMS but not updated
1354 // the prev bitmap.
1355 if (G1VerifyBitmaps) {
1356 GCTraceTime(Debug, gc)("Clear Bitmap for Verification");
1357 _cm->clear_prev_bitmap(workers());
1358 }
1359 _verifier->check_bitmaps("Full GC End");
1360
1361 start_new_collection_set();
1362
1363 _allocator->init_mutator_alloc_region();
1364
1365 g1_policy()->record_full_collection_end();
1366
1367 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1368 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1369 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1370 // before any GC notifications are raised.
1371 g1mm()->update_sizes();
1372
1373 gc_epilogue(true);
1374
1375 heap_transition.print();
1376
1377 print_heap_after_gc();
1378 print_heap_regions();
1379 trace_heap_after_gc(gc_tracer);
1380
1381 post_full_gc_dump(gc_timer);
1382 }
1383
1384 gc_timer->register_gc_end();
1385 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1386 }
1387
1388 return true;
1389 }
1390
1391 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1392 // Currently, there is no facility in the do_full_collection(bool) API to notify
1393 // the caller that the collection did not succeed (e.g., because it was locked
1394 // out by the GC locker). So, right now, we'll ignore the return value.
1395 bool dummy = do_full_collection(true, /* explicit_gc */
1396 clear_all_soft_refs);
1397 }
1398
1399 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1400 // Include bytes that will be pre-allocated to support collections, as "used".
1401 const size_t used_after_gc = used();
1402 const size_t capacity_after_gc = capacity();
1403 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1404
1405 // This is enforced in arguments.cpp.
1406 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1407 "otherwise the code below doesn't make sense");
1408
1409 // We don't have floating point command-line arguments
1410 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1411 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1412 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1413 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1414
1415 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1416 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1417
1418 // We have to be careful here as these two calculations can overflow
1419 // 32-bit size_t's.
1420 double used_after_gc_d = (double) used_after_gc;
1421 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1422 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1423
1424 // Let's make sure that they are both under the max heap size, which
1425 // by default will make them fit into a size_t.
1426 double desired_capacity_upper_bound = (double) max_heap_size;
1427 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1428 desired_capacity_upper_bound);
1429 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1430 desired_capacity_upper_bound);
1431
1432 // We can now safely turn them into size_t's.
1433 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1434 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1435
1436 // This assert only makes sense here, before we adjust them
1437 // with respect to the min and max heap size.
1438 assert(minimum_desired_capacity <= maximum_desired_capacity,
1439 "minimum_desired_capacity = " SIZE_FORMAT ", "
1440 "maximum_desired_capacity = " SIZE_FORMAT,
1441 minimum_desired_capacity, maximum_desired_capacity);
1442
1443 // Should not be greater than the heap max size. No need to adjust
1444 // it with respect to the heap min size as it's a lower bound (i.e.,
1445 // we'll try to make the capacity larger than it, not smaller).
1446 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1447 // Should not be less than the heap min size. No need to adjust it
1448 // with respect to the heap max size as it's an upper bound (i.e.,
1449 // we'll try to make the capacity smaller than it, not greater).
1450 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1451
1452 if (capacity_after_gc < minimum_desired_capacity) {
1453 // Don't expand unless it's significant
1454 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1455
1456 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1457 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1458 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1459
1460 expand(expand_bytes, _workers);
1461
1462 // No expansion, now see if we want to shrink
1463 } else if (capacity_after_gc > maximum_desired_capacity) {
1464 // Capacity too large, compute shrinking size
1465 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1466
1467 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1468 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1469 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1470
1471 shrink(shrink_bytes);
1472 }
1473 }
1474
1475 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1476 AllocationContext_t context,
1477 bool do_gc,
1478 bool clear_all_soft_refs,
1479 bool expect_null_mutator_alloc_region,
1480 bool* gc_succeeded) {
1481 *gc_succeeded = true;
1482 // Let's attempt the allocation first.
1483 HeapWord* result =
1484 attempt_allocation_at_safepoint(word_size,
1485 context,
1486 expect_null_mutator_alloc_region);
1487 if (result != NULL) {
1488 assert(*gc_succeeded, "sanity");
1489 return result;
1490 }
1491
1492 // In a G1 heap, we're supposed to keep allocation from failing by
1493 // incremental pauses. Therefore, at least for now, we'll favor
1494 // expansion over collection. (This might change in the future if we can
1495 // do something smarter than full collection to satisfy a failed alloc.)
1496 result = expand_and_allocate(word_size, context);
1497 if (result != NULL) {
1498 assert(*gc_succeeded, "sanity");
1499 return result;
1500 }
1501
1502 if (do_gc) {
1503 // Expansion didn't work, we'll try to do a Full GC.
1504 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1505 clear_all_soft_refs);
1506 }
1507
1508 return NULL;
1509 }
1510
1511 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1512 AllocationContext_t context,
1513 bool* succeeded) {
1514 assert_at_safepoint(true /* should_be_vm_thread */);
1515
1516 // Attempts to allocate followed by Full GC.
1517 HeapWord* result =
1518 satisfy_failed_allocation_helper(word_size,
1519 context,
1520 true, /* do_gc */
1521 false, /* clear_all_soft_refs */
1522 false, /* expect_null_mutator_alloc_region */
1523 succeeded);
1524
1525 if (result != NULL || !*succeeded) {
1526 return result;
1527 }
1528
1529 // Attempts to allocate followed by Full GC that will collect all soft references.
1530 result = satisfy_failed_allocation_helper(word_size,
1531 context,
1532 true, /* do_gc */
1533 true, /* clear_all_soft_refs */
1534 true, /* expect_null_mutator_alloc_region */
1535 succeeded);
1536
1537 if (result != NULL || !*succeeded) {
1538 return result;
1539 }
1540
1541 // Attempts to allocate, no GC
1542 result = satisfy_failed_allocation_helper(word_size,
1543 context,
1544 false, /* do_gc */
1545 false, /* clear_all_soft_refs */
1546 true, /* expect_null_mutator_alloc_region */
1547 succeeded);
1548
1549 if (result != NULL) {
1550 assert(*succeeded, "sanity");
1551 return result;
1552 }
1553
1554 assert(!collector_policy()->should_clear_all_soft_refs(),
1555 "Flag should have been handled and cleared prior to this point");
1556
1557 // What else? We might try synchronous finalization later. If the total
1558 // space available is large enough for the allocation, then a more
1559 // complete compaction phase than we've tried so far might be
1560 // appropriate.
1561 assert(*succeeded, "sanity");
1562 return NULL;
1563 }
1564
1565 // Attempting to expand the heap sufficiently
1566 // to support an allocation of the given "word_size". If
1567 // successful, perform the allocation and return the address of the
1568 // allocated block, or else "NULL".
1569
1570 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1571 assert_at_safepoint(true /* should_be_vm_thread */);
1572
1573 _verifier->verify_region_sets_optional();
1574
1575 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1576 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1577 word_size * HeapWordSize);
1578
1579
1580 if (expand(expand_bytes, _workers)) {
1581 _hrm.verify_optional();
1582 _verifier->verify_region_sets_optional();
1583 return attempt_allocation_at_safepoint(word_size,
1584 context,
1585 false /* expect_null_mutator_alloc_region */);
1586 }
1587 return NULL;
1588 }
1589
1590 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1591 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1592 aligned_expand_bytes = align_up(aligned_expand_bytes,
1593 HeapRegion::GrainBytes);
1594
1595 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1596 expand_bytes, aligned_expand_bytes);
1597
1598 if (is_maximal_no_gc()) {
1599 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1600 return false;
1601 }
1602
1603 double expand_heap_start_time_sec = os::elapsedTime();
1604 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1605 assert(regions_to_expand > 0, "Must expand by at least one region");
1606
1607 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1608 if (expand_time_ms != NULL) {
1609 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1610 }
1611
1612 if (expanded_by > 0) {
1613 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1614 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1615 g1_policy()->record_new_heap_size(num_regions());
1616 } else {
1617 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1618
1619 // The expansion of the virtual storage space was unsuccessful.
1620 // Let's see if it was because we ran out of swap.
1621 if (G1ExitOnExpansionFailure &&
1622 _hrm.available() >= regions_to_expand) {
1623 // We had head room...
1624 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1625 }
1626 }
1627 return regions_to_expand > 0;
1628 }
1629
1630 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1631 size_t aligned_shrink_bytes =
1632 ReservedSpace::page_align_size_down(shrink_bytes);
1633 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1634 HeapRegion::GrainBytes);
1635 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1636
1637 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1638 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1639
1640
1641 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",
1642 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1643 if (num_regions_removed > 0) {
1644 g1_policy()->record_new_heap_size(num_regions());
1645 } else {
1646 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1647 }
1648 }
1649
1650 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1651 _verifier->verify_region_sets_optional();
1652
1653 // We should only reach here at the end of a Full GC which means we
1654 // should not not be holding to any GC alloc regions. The method
1655 // below will make sure of that and do any remaining clean up.
1656 _allocator->abandon_gc_alloc_regions();
1657
1658 // Instead of tearing down / rebuilding the free lists here, we
1659 // could instead use the remove_all_pending() method on free_list to
1660 // remove only the ones that we need to remove.
1661 tear_down_region_sets(true /* free_list_only */);
1662 shrink_helper(shrink_bytes);
1663 rebuild_region_sets(true /* free_list_only */);
1664
1665 _hrm.verify_optional();
1666 _verifier->verify_region_sets_optional();
1667 }
1668
1669 // Public methods.
1670
1671 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1672 CollectedHeap(),
1673 _collector_policy(collector_policy),
1674 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1675 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1676 _g1_policy(create_g1_policy(_gc_timer_stw)),
1677 _collection_set(this, _g1_policy),
1678 _dirty_card_queue_set(false),
1679 _is_alive_closure_cm(this),
1680 _is_alive_closure_stw(this),
1681 _ref_processor_cm(NULL),
1682 _ref_processor_stw(NULL),
1683 _bot(NULL),
1684 _hot_card_cache(NULL),
1685 _g1_rem_set(NULL),
1686 _cg1r(NULL),
1687 _g1mm(NULL),
1688 _preserved_marks_set(true /* in_c_heap */),
1689 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1690 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1691 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1692 _humongous_reclaim_candidates(),
1693 _has_humongous_reclaim_candidates(false),
1694 _archive_allocator(NULL),
1695 _free_regions_coming(false),
1696 _gc_time_stamp(0),
1697 _summary_bytes_used(0),
1698 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1699 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1700 _expand_heap_after_alloc_failure(true),
1701 _old_marking_cycles_started(0),
1702 _old_marking_cycles_completed(0),
1703 _in_cset_fast_test() {
1704
1705 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1706 /* are_GC_task_threads */true,
1707 /* are_ConcurrentGC_threads */false);
1708 _workers->initialize_workers();
1709 _verifier = new G1HeapVerifier(this);
1710
1711 _allocator = G1Allocator::create_allocator(this);
1712
1713 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1714
1715 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1716
1717 // Override the default _filler_array_max_size so that no humongous filler
1718 // objects are created.
1719 _filler_array_max_size = _humongous_object_threshold_in_words;
1720
1721 uint n_queues = ParallelGCThreads;
1722 _task_queues = new RefToScanQueueSet(n_queues);
1723
1724 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1725
1726 for (uint i = 0; i < n_queues; i++) {
1727 RefToScanQueue* q = new RefToScanQueue();
1728 q->initialize();
1729 _task_queues->register_queue(i, q);
1730 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1731 }
1732
1733 // Initialize the G1EvacuationFailureALot counters and flags.
1734 NOT_PRODUCT(reset_evacuation_should_fail();)
1735
1736 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1737 }
1738
1739 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1740 size_t size,
1741 size_t translation_factor) {
1742 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1743 // Allocate a new reserved space, preferring to use large pages.
1744 ReservedSpace rs(size, preferred_page_size);
1745 G1RegionToSpaceMapper* result =
1746 G1RegionToSpaceMapper::create_mapper(rs,
1747 size,
1748 rs.alignment(),
1749 HeapRegion::GrainBytes,
1750 translation_factor,
1751 mtGC);
1752
1753 os::trace_page_sizes_for_requested_size(description,
1754 size,
1755 preferred_page_size,
1756 rs.alignment(),
1757 rs.base(),
1758 rs.size());
1759
1760 return result;
1761 }
1762
1763 jint G1CollectedHeap::initialize_concurrent_refinement() {
1764 jint ecode = JNI_OK;
1765 _cg1r = ConcurrentG1Refine::create(&ecode);
1766 return ecode;
1767 }
1768
1769 jint G1CollectedHeap::initialize() {
1770 CollectedHeap::pre_initialize();
1771 os::enable_vtime();
1772
1773 // Necessary to satisfy locking discipline assertions.
1774
1775 MutexLocker x(Heap_lock);
1776
1777 // While there are no constraints in the GC code that HeapWordSize
1778 // be any particular value, there are multiple other areas in the
1779 // system which believe this to be true (e.g. oop->object_size in some
1780 // cases incorrectly returns the size in wordSize units rather than
1781 // HeapWordSize).
1782 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1783
1784 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1785 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1786 size_t heap_alignment = collector_policy()->heap_alignment();
1787
1788 // Ensure that the sizes are properly aligned.
1789 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1790 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1791 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1792
1793 // Reserve the maximum.
1794
1795 // When compressed oops are enabled, the preferred heap base
1796 // is calculated by subtracting the requested size from the
1797 // 32Gb boundary and using the result as the base address for
1798 // heap reservation. If the requested size is not aligned to
1799 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1800 // into the ReservedHeapSpace constructor) then the actual
1801 // base of the reserved heap may end up differing from the
1802 // address that was requested (i.e. the preferred heap base).
1803 // If this happens then we could end up using a non-optimal
1804 // compressed oops mode.
1805
1806 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1807 heap_alignment);
1808
1809 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1810
1811 // Create the barrier set for the entire reserved region.
1812 G1SATBCardTableLoggingModRefBS* bs
1813 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1814 bs->initialize();
1815 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1816 set_barrier_set(bs);
1817
1818 // Create the hot card cache.
1819 _hot_card_cache = new G1HotCardCache(this);
1820
1821 // Carve out the G1 part of the heap.
1822 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1823 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1824 G1RegionToSpaceMapper* heap_storage =
1825 G1RegionToSpaceMapper::create_mapper(g1_rs,
1826 g1_rs.size(),
1827 page_size,
1828 HeapRegion::GrainBytes,
1829 1,
1830 mtJavaHeap);
1831 os::trace_page_sizes("Heap",
1832 collector_policy()->min_heap_byte_size(),
1833 max_byte_size,
1834 page_size,
1835 heap_rs.base(),
1836 heap_rs.size());
1837 heap_storage->set_mapping_changed_listener(&_listener);
1838
1839 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1840 G1RegionToSpaceMapper* bot_storage =
1841 create_aux_memory_mapper("Block Offset Table",
1842 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1843 G1BlockOffsetTable::heap_map_factor());
1844
1845 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1846 G1RegionToSpaceMapper* cardtable_storage =
1847 create_aux_memory_mapper("Card Table",
1848 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1849 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1850
1851 G1RegionToSpaceMapper* card_counts_storage =
1852 create_aux_memory_mapper("Card Counts Table",
1853 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1854 G1CardCounts::heap_map_factor());
1855
1856 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1857 G1RegionToSpaceMapper* prev_bitmap_storage =
1858 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1859 G1RegionToSpaceMapper* next_bitmap_storage =
1860 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1861
1862 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1863 g1_barrier_set()->initialize(cardtable_storage);
1864 // Do later initialization work for concurrent refinement.
1865 _hot_card_cache->initialize(card_counts_storage);
1866
1867 // 6843694 - ensure that the maximum region index can fit
1868 // in the remembered set structures.
1869 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1870 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1871
1872 // Also create a G1 rem set.
1873 _g1_rem_set = new G1RemSet(this, g1_barrier_set(), _hot_card_cache);
1874 _g1_rem_set->initialize(max_capacity(), max_regions());
1875
1876 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1877 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1878 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1879 "too many cards per region");
1880
1881 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1882
1883 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1884
1885 {
1886 HeapWord* start = _hrm.reserved().start();
1887 HeapWord* end = _hrm.reserved().end();
1888 size_t granularity = HeapRegion::GrainBytes;
1889
1890 _in_cset_fast_test.initialize(start, end, granularity);
1891 _humongous_reclaim_candidates.initialize(start, end, granularity);
1892 }
1893
1894 // Create the G1ConcurrentMark data structure and thread.
1895 // (Must do this late, so that "max_regions" is defined.)
1896 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1897 if (_cm == NULL || !_cm->completed_initialization()) {
1898 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1899 return JNI_ENOMEM;
1900 }
1901 _cmThread = _cm->cmThread();
1902
1903 // Now expand into the initial heap size.
1904 if (!expand(init_byte_size, _workers)) {
1905 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1906 return JNI_ENOMEM;
1907 }
1908
1909 // Perform any initialization actions delegated to the policy.
1910 g1_policy()->init(this, &_collection_set);
1911
1912 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1913 SATB_Q_FL_lock,
1914 G1SATBProcessCompletedThreshold,
1915 Shared_SATB_Q_lock);
1916
1917 jint ecode = initialize_concurrent_refinement();
1918 if (ecode != JNI_OK) {
1919 return ecode;
1920 }
1921
1922 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1923 DirtyCardQ_FL_lock,
1924 (int)concurrent_g1_refine()->yellow_zone(),
1925 (int)concurrent_g1_refine()->red_zone(),
1926 Shared_DirtyCardQ_lock,
1927 NULL, // fl_owner
1928 true); // init_free_ids
1929
1930 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1931 DirtyCardQ_FL_lock,
1932 -1, // never trigger processing
1933 -1, // no limit on length
1934 Shared_DirtyCardQ_lock,
1935 &JavaThread::dirty_card_queue_set());
1936
1937 // Here we allocate the dummy HeapRegion that is required by the
1938 // G1AllocRegion class.
1939 HeapRegion* dummy_region = _hrm.get_dummy_region();
1940
1941 // We'll re-use the same region whether the alloc region will
1942 // require BOT updates or not and, if it doesn't, then a non-young
1943 // region will complain that it cannot support allocations without
1944 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1945 dummy_region->set_eden();
1946 // Make sure it's full.
1947 dummy_region->set_top(dummy_region->end());
1948 G1AllocRegion::setup(this, dummy_region);
1949
1950 _allocator->init_mutator_alloc_region();
1951
1952 // Do create of the monitoring and management support so that
1953 // values in the heap have been properly initialized.
1954 _g1mm = new G1MonitoringSupport(this);
1955
1956 G1StringDedup::initialize();
1957
1958 _preserved_marks_set.init(ParallelGCThreads);
1959
1960 _collection_set.initialize(max_regions());
1961
1962 return JNI_OK;
1963 }
1964
1965 void G1CollectedHeap::stop() {
1966 // Stop all concurrent threads. We do this to make sure these threads
1967 // do not continue to execute and access resources (e.g. logging)
1968 // that are destroyed during shutdown.
1969 _cg1r->stop();
1970 _cmThread->stop();
1971 if (G1StringDedup::is_enabled()) {
1972 G1StringDedup::stop();
1973 }
1974 }
1975
1976 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1977 return HeapRegion::max_region_size();
1978 }
1979
1980 void G1CollectedHeap::post_initialize() {
1981 ref_processing_init();
1982 }
1983
1984 void G1CollectedHeap::ref_processing_init() {
1985 // Reference processing in G1 currently works as follows:
1986 //
1987 // * There are two reference processor instances. One is
1988 // used to record and process discovered references
1989 // during concurrent marking; the other is used to
1990 // record and process references during STW pauses
1991 // (both full and incremental).
1992 // * Both ref processors need to 'span' the entire heap as
1993 // the regions in the collection set may be dotted around.
1994 //
1995 // * For the concurrent marking ref processor:
1996 // * Reference discovery is enabled at initial marking.
1997 // * Reference discovery is disabled and the discovered
1998 // references processed etc during remarking.
1999 // * Reference discovery is MT (see below).
2000 // * Reference discovery requires a barrier (see below).
2001 // * Reference processing may or may not be MT
2002 // (depending on the value of ParallelRefProcEnabled
2003 // and ParallelGCThreads).
2004 // * A full GC disables reference discovery by the CM
2005 // ref processor and abandons any entries on it's
2006 // discovered lists.
2007 //
2008 // * For the STW processor:
2009 // * Non MT discovery is enabled at the start of a full GC.
2010 // * Processing and enqueueing during a full GC is non-MT.
2011 // * During a full GC, references are processed after marking.
2012 //
2013 // * Discovery (may or may not be MT) is enabled at the start
2014 // of an incremental evacuation pause.
2015 // * References are processed near the end of a STW evacuation pause.
2016 // * For both types of GC:
2017 // * Discovery is atomic - i.e. not concurrent.
2018 // * Reference discovery will not need a barrier.
2019
2020 MemRegion mr = reserved_region();
2021
2022 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
2023
2024 // Concurrent Mark ref processor
2025 _ref_processor_cm =
2026 new ReferenceProcessor(mr, // span
2027 mt_processing,
2028 // mt processing
2029 ParallelGCThreads,
2030 // degree of mt processing
2031 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2032 // mt discovery
2033 MAX2(ParallelGCThreads, ConcGCThreads),
2034 // degree of mt discovery
2035 false,
2036 // Reference discovery is not atomic
2037 &_is_alive_closure_cm);
2038 // is alive closure
2039 // (for efficiency/performance)
2040
2041 // STW ref processor
2042 _ref_processor_stw =
2043 new ReferenceProcessor(mr, // span
2044 mt_processing,
2045 // mt processing
2046 ParallelGCThreads,
2047 // degree of mt processing
2048 (ParallelGCThreads > 1),
2049 // mt discovery
2050 ParallelGCThreads,
2051 // degree of mt discovery
2052 true,
2053 // Reference discovery is atomic
2054 &_is_alive_closure_stw);
2055 // is alive closure
2056 // (for efficiency/performance)
2057 }
2058
2059 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2060 return _collector_policy;
2061 }
2062
2063 size_t G1CollectedHeap::capacity() const {
2064 return _hrm.length() * HeapRegion::GrainBytes;
2065 }
2066
2067 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2068 hr->reset_gc_time_stamp();
2069 }
2070
2071 #ifndef PRODUCT
2072
2073 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2074 private:
2075 unsigned _gc_time_stamp;
2076 bool _failures;
2077
2078 public:
2079 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2080 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2081
2082 virtual bool doHeapRegion(HeapRegion* hr) {
2083 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2084 if (_gc_time_stamp != region_gc_time_stamp) {
2085 log_error(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2086 region_gc_time_stamp, _gc_time_stamp);
2087 _failures = true;
2088 }
2089 return false;
2090 }
2091
2092 bool failures() { return _failures; }
2093 };
2094
2095 void G1CollectedHeap::check_gc_time_stamps() {
2096 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2097 heap_region_iterate(&cl);
2098 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2099 }
2100 #endif // PRODUCT
2101
2102 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2103 _hot_card_cache->drain(cl, worker_i);
2104 }
2105
2106 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2107 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2108 size_t n_completed_buffers = 0;
2109 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
2110 n_completed_buffers++;
2111 }
2112 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2113 dcqs.clear_n_completed_buffers();
2114 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2115 }
2116
2117 // Computes the sum of the storage used by the various regions.
2118 size_t G1CollectedHeap::used() const {
2119 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2120 if (_archive_allocator != NULL) {
2121 result += _archive_allocator->used();
2122 }
2123 return result;
2124 }
2125
2126 size_t G1CollectedHeap::used_unlocked() const {
2127 return _summary_bytes_used;
2128 }
2129
2130 class SumUsedClosure: public HeapRegionClosure {
2131 size_t _used;
2132 public:
2133 SumUsedClosure() : _used(0) {}
2134 bool doHeapRegion(HeapRegion* r) {
2135 _used += r->used();
2136 return false;
2137 }
2138 size_t result() { return _used; }
2139 };
2140
2141 size_t G1CollectedHeap::recalculate_used() const {
2142 double recalculate_used_start = os::elapsedTime();
2143
2144 SumUsedClosure blk;
2145 heap_region_iterate(&blk);
2146
2147 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2148 return blk.result();
2149 }
2150
2151 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2152 switch (cause) {
2153 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2154 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2155 case GCCause::_update_allocation_context_stats_inc: return true;
2156 case GCCause::_wb_conc_mark: return true;
2157 default : return false;
2158 }
2159 }
2160
2161 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2162 switch (cause) {
2163 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2164 case GCCause::_g1_humongous_allocation: return true;
2165 default: return is_user_requested_concurrent_full_gc(cause);
2166 }
2167 }
2168
2169 #ifndef PRODUCT
2170 void G1CollectedHeap::allocate_dummy_regions() {
2171 // Let's fill up most of the region
2172 size_t word_size = HeapRegion::GrainWords - 1024;
2173 // And as a result the region we'll allocate will be humongous.
2174 guarantee(is_humongous(word_size), "sanity");
2175
2176 // _filler_array_max_size is set to humongous object threshold
2177 // but temporarily change it to use CollectedHeap::fill_with_object().
2178 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2179
2180 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2181 // Let's use the existing mechanism for the allocation
2182 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2183 AllocationContext::system());
2184 if (dummy_obj != NULL) {
2185 MemRegion mr(dummy_obj, word_size);
2186 CollectedHeap::fill_with_object(mr);
2187 } else {
2188 // If we can't allocate once, we probably cannot allocate
2189 // again. Let's get out of the loop.
2190 break;
2191 }
2192 }
2193 }
2194 #endif // !PRODUCT
2195
2196 void G1CollectedHeap::increment_old_marking_cycles_started() {
2197 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2198 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2199 "Wrong marking cycle count (started: %d, completed: %d)",
2200 _old_marking_cycles_started, _old_marking_cycles_completed);
2201
2202 _old_marking_cycles_started++;
2203 }
2204
2205 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2206 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2207
2208 // We assume that if concurrent == true, then the caller is a
2209 // concurrent thread that was joined the Suspendible Thread
2210 // Set. If there's ever a cheap way to check this, we should add an
2211 // assert here.
2212
2213 // Given that this method is called at the end of a Full GC or of a
2214 // concurrent cycle, and those can be nested (i.e., a Full GC can
2215 // interrupt a concurrent cycle), the number of full collections
2216 // completed should be either one (in the case where there was no
2217 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2218 // behind the number of full collections started.
2219
2220 // This is the case for the inner caller, i.e. a Full GC.
2221 assert(concurrent ||
2222 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2223 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2224 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2225 "is inconsistent with _old_marking_cycles_completed = %u",
2226 _old_marking_cycles_started, _old_marking_cycles_completed);
2227
2228 // This is the case for the outer caller, i.e. the concurrent cycle.
2229 assert(!concurrent ||
2230 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2231 "for outer caller (concurrent cycle): "
2232 "_old_marking_cycles_started = %u "
2233 "is inconsistent with _old_marking_cycles_completed = %u",
2234 _old_marking_cycles_started, _old_marking_cycles_completed);
2235
2236 _old_marking_cycles_completed += 1;
2237
2238 // We need to clear the "in_progress" flag in the CM thread before
2239 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2240 // is set) so that if a waiter requests another System.gc() it doesn't
2241 // incorrectly see that a marking cycle is still in progress.
2242 if (concurrent) {
2243 _cmThread->set_idle();
2244 }
2245
2246 // This notify_all() will ensure that a thread that called
2247 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2248 // and it's waiting for a full GC to finish will be woken up. It is
2249 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2250 FullGCCount_lock->notify_all();
2251 }
2252
2253 void G1CollectedHeap::collect(GCCause::Cause cause) {
2254 assert_heap_not_locked();
2255
2256 uint gc_count_before;
2257 uint old_marking_count_before;
2258 uint full_gc_count_before;
2259 bool retry_gc;
2260
2261 do {
2262 retry_gc = false;
2263
2264 {
2265 MutexLocker ml(Heap_lock);
2266
2267 // Read the GC count while holding the Heap_lock
2268 gc_count_before = total_collections();
2269 full_gc_count_before = total_full_collections();
2270 old_marking_count_before = _old_marking_cycles_started;
2271 }
2272
2273 if (should_do_concurrent_full_gc(cause)) {
2274 // Schedule an initial-mark evacuation pause that will start a
2275 // concurrent cycle. We're setting word_size to 0 which means that
2276 // we are not requesting a post-GC allocation.
2277 VM_G1IncCollectionPause op(gc_count_before,
2278 0, /* word_size */
2279 true, /* should_initiate_conc_mark */
2280 g1_policy()->max_pause_time_ms(),
2281 cause);
2282 op.set_allocation_context(AllocationContext::current());
2283
2284 VMThread::execute(&op);
2285 if (!op.pause_succeeded()) {
2286 if (old_marking_count_before == _old_marking_cycles_started) {
2287 retry_gc = op.should_retry_gc();
2288 } else {
2289 // A Full GC happened while we were trying to schedule the
2290 // initial-mark GC. No point in starting a new cycle given
2291 // that the whole heap was collected anyway.
2292 }
2293
2294 if (retry_gc) {
2295 if (GCLocker::is_active_and_needs_gc()) {
2296 GCLocker::stall_until_clear();
2297 }
2298 }
2299 }
2300 } else {
2301 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2302 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2303
2304 // Schedule a standard evacuation pause. We're setting word_size
2305 // to 0 which means that we are not requesting a post-GC allocation.
2306 VM_G1IncCollectionPause op(gc_count_before,
2307 0, /* word_size */
2308 false, /* should_initiate_conc_mark */
2309 g1_policy()->max_pause_time_ms(),
2310 cause);
2311 VMThread::execute(&op);
2312 } else {
2313 // Schedule a Full GC.
2314 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2315 VMThread::execute(&op);
2316 }
2317 }
2318 } while (retry_gc);
2319 }
2320
2321 bool G1CollectedHeap::is_in(const void* p) const {
2322 if (_hrm.reserved().contains(p)) {
2323 // Given that we know that p is in the reserved space,
2324 // heap_region_containing() should successfully
2325 // return the containing region.
2326 HeapRegion* hr = heap_region_containing(p);
2327 return hr->is_in(p);
2328 } else {
2329 return false;
2330 }
2331 }
2332
2333 #ifdef ASSERT
2334 bool G1CollectedHeap::is_in_exact(const void* p) const {
2335 bool contains = reserved_region().contains(p);
2336 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2337 if (contains && available) {
2338 return true;
2339 } else {
2340 return false;
2341 }
2342 }
2343 #endif
2344
2345 // Iteration functions.
2346
2347 // Iterates an ObjectClosure over all objects within a HeapRegion.
2348
2349 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2350 ObjectClosure* _cl;
2351 public:
2352 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2353 bool doHeapRegion(HeapRegion* r) {
2354 if (!r->is_continues_humongous()) {
2355 r->object_iterate(_cl);
2356 }
2357 return false;
2358 }
2359 };
2360
2361 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2362 IterateObjectClosureRegionClosure blk(cl);
2363 heap_region_iterate(&blk);
2364 }
2365
2366 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2367 _hrm.iterate(cl);
2368 }
2369
2370 void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2371 uint worker_id,
2372 HeapRegionClaimer *hrclaimer) const {
2373 _hrm.par_iterate(cl, worker_id, hrclaimer);
2374 }
2375
2376 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2377 _collection_set.iterate(cl);
2378 }
2379
2380 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2381 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2382 }
2383
2384 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2385 HeapRegion* result = _hrm.next_region_in_heap(from);
2386 while (result != NULL && result->is_pinned()) {
2387 result = _hrm.next_region_in_heap(result);
2388 }
2389 return result;
2390 }
2391
2392 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2393 HeapRegion* hr = heap_region_containing(addr);
2394 return hr->block_start(addr);
2395 }
2396
2397 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2398 HeapRegion* hr = heap_region_containing(addr);
2399 return hr->block_size(addr);
2400 }
2401
2402 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2403 HeapRegion* hr = heap_region_containing(addr);
2404 return hr->block_is_obj(addr);
2405 }
2406
2407 bool G1CollectedHeap::supports_tlab_allocation() const {
2408 return true;
2409 }
2410
2411 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2412 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2413 }
2414
2415 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2416 return _eden.length() * HeapRegion::GrainBytes;
2417 }
2418
2419 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2420 // must be equal to the humongous object limit.
2421 size_t G1CollectedHeap::max_tlab_size() const {
2422 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2423 }
2424
2425 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2426 AllocationContext_t context = AllocationContext::current();
2427 return _allocator->unsafe_max_tlab_alloc(context);
2428 }
2429
2430 size_t G1CollectedHeap::max_capacity() const {
2431 return _hrm.reserved().byte_size();
2432 }
2433
2434 jlong G1CollectedHeap::millis_since_last_gc() {
2435 // See the notes in GenCollectedHeap::millis_since_last_gc()
2436 // for more information about the implementation.
2437 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2438 _g1_policy->collection_pause_end_millis();
2439 if (ret_val < 0) {
2440 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2441 ". returning zero instead.", ret_val);
2442 return 0;
2443 }
2444 return ret_val;
2445 }
2446
2447 void G1CollectedHeap::prepare_for_verify() {
2448 _verifier->prepare_for_verify();
2449 }
2450
2451 void G1CollectedHeap::verify(VerifyOption vo) {
2452 _verifier->verify(vo);
2453 }
2454
2455 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2456 return true;
2457 }
2458
2459 const char* const* G1CollectedHeap::concurrent_phases() const {
2460 return _cmThread->concurrent_phases();
2461 }
2462
2463 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2464 return _cmThread->request_concurrent_phase(phase);
2465 }
2466
2467 class PrintRegionClosure: public HeapRegionClosure {
2468 outputStream* _st;
2469 public:
2470 PrintRegionClosure(outputStream* st) : _st(st) {}
2471 bool doHeapRegion(HeapRegion* r) {
2472 r->print_on(_st);
2473 return false;
2474 }
2475 };
2476
2477 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2478 const HeapRegion* hr,
2479 const VerifyOption vo) const {
2480 switch (vo) {
2481 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2482 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2483 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2484 default: ShouldNotReachHere();
2485 }
2486 return false; // keep some compilers happy
2487 }
2488
2489 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2490 const VerifyOption vo) const {
2491 switch (vo) {
2492 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2493 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2494 case VerifyOption_G1UseMarkWord: {
2495 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2496 return !obj->is_gc_marked() && !hr->is_archive();
2497 }
2498 default: ShouldNotReachHere();
2499 }
2500 return false; // keep some compilers happy
2501 }
2502
2503 void G1CollectedHeap::print_heap_regions() const {
2504 LogTarget(Trace, gc, heap, region) lt;
2505 if (lt.is_enabled()) {
2506 LogStream ls(lt);
2507 print_regions_on(&ls);
2508 }
2509 }
2510
2511 void G1CollectedHeap::print_on(outputStream* st) const {
2512 st->print(" %-20s", "garbage-first heap");
2513 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2514 capacity()/K, used_unlocked()/K);
2515 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2516 p2i(_hrm.reserved().start()),
2517 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2518 p2i(_hrm.reserved().end()));
2519 st->cr();
2520 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2521 uint young_regions = young_regions_count();
2522 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2523 (size_t) young_regions * HeapRegion::GrainBytes / K);
2524 uint survivor_regions = survivor_regions_count();
2525 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2526 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2527 st->cr();
2528 MetaspaceAux::print_on(st);
2529 }
2530
2531 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2532 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2533 "HS=humongous(starts), HC=humongous(continues), "
2534 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2535 "AC=allocation context, "
2536 "TAMS=top-at-mark-start (previous, next)");
2537 PrintRegionClosure blk(st);
2538 heap_region_iterate(&blk);
2539 }
2540
2541 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2542 print_on(st);
2543
2544 // Print the per-region information.
2545 print_regions_on(st);
2546 }
2547
2548 void G1CollectedHeap::print_on_error(outputStream* st) const {
2549 this->CollectedHeap::print_on_error(st);
2550
2551 if (_cm != NULL) {
2552 st->cr();
2553 _cm->print_on_error(st);
2554 }
2555 }
2556
2557 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2558 workers()->print_worker_threads_on(st);
2559 _cmThread->print_on(st);
2560 st->cr();
2561 _cm->print_worker_threads_on(st);
2562 _cg1r->print_worker_threads_on(st); // also prints the sample thread
2563 if (G1StringDedup::is_enabled()) {
2564 G1StringDedup::print_worker_threads_on(st);
2565 }
2566 }
2567
2568 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2569 workers()->threads_do(tc);
2570 tc->do_thread(_cmThread);
2571 _cm->threads_do(tc);
2572 _cg1r->threads_do(tc); // also iterates over the sample thread
2573 if (G1StringDedup::is_enabled()) {
2574 G1StringDedup::threads_do(tc);
2575 }
2576 }
2577
2578 void G1CollectedHeap::print_tracing_info() const {
2579 g1_rem_set()->print_summary_info();
2580 concurrent_mark()->print_summary_info();
2581 }
2582
2583 #ifndef PRODUCT
2584 // Helpful for debugging RSet issues.
2585
2586 class PrintRSetsClosure : public HeapRegionClosure {
2587 private:
2588 const char* _msg;
2589 size_t _occupied_sum;
2590
2591 public:
2592 bool doHeapRegion(HeapRegion* r) {
2593 HeapRegionRemSet* hrrs = r->rem_set();
2594 size_t occupied = hrrs->occupied();
2595 _occupied_sum += occupied;
2596
2597 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2598 if (occupied == 0) {
2599 tty->print_cr(" RSet is empty");
2600 } else {
2601 hrrs->print();
2602 }
2603 tty->print_cr("----------");
2604 return false;
2605 }
2606
2607 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2608 tty->cr();
2609 tty->print_cr("========================================");
2610 tty->print_cr("%s", msg);
2611 tty->cr();
2612 }
2613
2614 ~PrintRSetsClosure() {
2615 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2616 tty->print_cr("========================================");
2617 tty->cr();
2618 }
2619 };
2620
2621 void G1CollectedHeap::print_cset_rsets() {
2622 PrintRSetsClosure cl("Printing CSet RSets");
2623 collection_set_iterate(&cl);
2624 }
2625
2626 void G1CollectedHeap::print_all_rsets() {
2627 PrintRSetsClosure cl("Printing All RSets");;
2628 heap_region_iterate(&cl);
2629 }
2630 #endif // PRODUCT
2631
2632 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2633
2634 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2635 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2636 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2637
2638 size_t eden_capacity_bytes =
2639 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2640
2641 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2642 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2643 eden_capacity_bytes, survivor_used_bytes, num_regions());
2644 }
2645
2646 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2647 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2648 stats->unused(), stats->used(), stats->region_end_waste(),
2649 stats->regions_filled(), stats->direct_allocated(),
2650 stats->failure_used(), stats->failure_waste());
2651 }
2652
2653 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2654 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2655 gc_tracer->report_gc_heap_summary(when, heap_summary);
2656
2657 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2658 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2659 }
2660
2661 G1CollectedHeap* G1CollectedHeap::heap() {
2662 CollectedHeap* heap = Universe::heap();
2663 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2664 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2665 return (G1CollectedHeap*)heap;
2666 }
2667
2668 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2669 // always_do_update_barrier = false;
2670 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2671
2672 double start = os::elapsedTime();
2673 // Fill TLAB's and such
2674 accumulate_statistics_all_tlabs();
2675 ensure_parsability(true);
2676 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2677
2678 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2679 }
2680
2681 void G1CollectedHeap::gc_epilogue(bool full) {
2682 // we are at the end of the GC. Total collections has already been increased.
2683 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2684
2685 // FIXME: what is this about?
2686 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2687 // is set.
2688 #if defined(COMPILER2) || INCLUDE_JVMCI
2689 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2690 #endif
2691 // always_do_update_barrier = true;
2692
2693 double start = os::elapsedTime();
2694 resize_all_tlabs();
2695 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2696
2697 allocation_context_stats().update(full);
2698
2699 // We have just completed a GC. Update the soft reference
2700 // policy with the new heap occupancy
2701 Universe::update_heap_info_at_gc();
2702 }
2703
2704 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2705 uint gc_count_before,
2706 bool* succeeded,
2707 GCCause::Cause gc_cause) {
2708 assert_heap_not_locked_and_not_at_safepoint();
2709 VM_G1IncCollectionPause op(gc_count_before,
2710 word_size,
2711 false, /* should_initiate_conc_mark */
2712 g1_policy()->max_pause_time_ms(),
2713 gc_cause);
2714
2715 op.set_allocation_context(AllocationContext::current());
2716 VMThread::execute(&op);
2717
2718 HeapWord* result = op.result();
2719 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2720 assert(result == NULL || ret_succeeded,
2721 "the result should be NULL if the VM did not succeed");
2722 *succeeded = ret_succeeded;
2723
2724 assert_heap_not_locked();
2725 return result;
2726 }
2727
2728 void
2729 G1CollectedHeap::doConcurrentMark() {
2730 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2731 if (!_cmThread->in_progress()) {
2732 _cmThread->set_started();
2733 CGC_lock->notify();
2734 }
2735 }
2736
2737 size_t G1CollectedHeap::pending_card_num() {
2738 size_t extra_cards = 0;
2739 JavaThread *curr = Threads::first();
2740 while (curr != NULL) {
2741 DirtyCardQueue& dcq = curr->dirty_card_queue();
2742 extra_cards += dcq.size();
2743 curr = curr->next();
2744 }
2745 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2746 size_t buffer_size = dcqs.buffer_size();
2747 size_t buffer_num = dcqs.completed_buffers_num();
2748
2749 return buffer_size * buffer_num + extra_cards;
2750 }
2751
2752 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2753 private:
2754 size_t _total_humongous;
2755 size_t _candidate_humongous;
2756
2757 DirtyCardQueue _dcq;
2758
2759 // We don't nominate objects with many remembered set entries, on
2760 // the assumption that such objects are likely still live.
2761 bool is_remset_small(HeapRegion* region) const {
2762 HeapRegionRemSet* const rset = region->rem_set();
2763 return G1EagerReclaimHumongousObjectsWithStaleRefs
2764 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2765 : rset->is_empty();
2766 }
2767
2768 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2769 assert(region->is_starts_humongous(), "Must start a humongous object");
2770
2771 oop obj = oop(region->bottom());
2772
2773 // Dead objects cannot be eager reclaim candidates. Due to class
2774 // unloading it is unsafe to query their classes so we return early.
2775 if (heap->is_obj_dead(obj, region)) {
2776 return false;
2777 }
2778
2779 // Candidate selection must satisfy the following constraints
2780 // while concurrent marking is in progress:
2781 //
2782 // * In order to maintain SATB invariants, an object must not be
2783 // reclaimed if it was allocated before the start of marking and
2784 // has not had its references scanned. Such an object must have
2785 // its references (including type metadata) scanned to ensure no
2786 // live objects are missed by the marking process. Objects
2787 // allocated after the start of concurrent marking don't need to
2788 // be scanned.
2789 //
2790 // * An object must not be reclaimed if it is on the concurrent
2791 // mark stack. Objects allocated after the start of concurrent
2792 // marking are never pushed on the mark stack.
2793 //
2794 // Nominating only objects allocated after the start of concurrent
2795 // marking is sufficient to meet both constraints. This may miss
2796 // some objects that satisfy the constraints, but the marking data
2797 // structures don't support efficiently performing the needed
2798 // additional tests or scrubbing of the mark stack.
2799 //
2800 // However, we presently only nominate is_typeArray() objects.
2801 // A humongous object containing references induces remembered
2802 // set entries on other regions. In order to reclaim such an
2803 // object, those remembered sets would need to be cleaned up.
2804 //
2805 // We also treat is_typeArray() objects specially, allowing them
2806 // to be reclaimed even if allocated before the start of
2807 // concurrent mark. For this we rely on mark stack insertion to
2808 // exclude is_typeArray() objects, preventing reclaiming an object
2809 // that is in the mark stack. We also rely on the metadata for
2810 // such objects to be built-in and so ensured to be kept live.
2811 // Frequent allocation and drop of large binary blobs is an
2812 // important use case for eager reclaim, and this special handling
2813 // may reduce needed headroom.
2814
2815 return obj->is_typeArray() && is_remset_small(region);
2816 }
2817
2818 public:
2819 RegisterHumongousWithInCSetFastTestClosure()
2820 : _total_humongous(0),
2821 _candidate_humongous(0),
2822 _dcq(&JavaThread::dirty_card_queue_set()) {
2823 }
2824
2825 virtual bool doHeapRegion(HeapRegion* r) {
2826 if (!r->is_starts_humongous()) {
2827 return false;
2828 }
2829 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2830
2831 bool is_candidate = humongous_region_is_candidate(g1h, r);
2832 uint rindex = r->hrm_index();
2833 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2834 if (is_candidate) {
2835 _candidate_humongous++;
2836 g1h->register_humongous_region_with_cset(rindex);
2837 // Is_candidate already filters out humongous object with large remembered sets.
2838 // If we have a humongous object with a few remembered sets, we simply flush these
2839 // remembered set entries into the DCQS. That will result in automatic
2840 // re-evaluation of their remembered set entries during the following evacuation
2841 // phase.
2842 if (!r->rem_set()->is_empty()) {
2843 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2844 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2845 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
2846 HeapRegionRemSetIterator hrrs(r->rem_set());
2847 size_t card_index;
2848 while (hrrs.has_next(card_index)) {
2849 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
2850 // The remembered set might contain references to already freed
2851 // regions. Filter out such entries to avoid failing card table
2852 // verification.
2853 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
2854 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
2855 *card_ptr = CardTableModRefBS::dirty_card_val();
2856 _dcq.enqueue(card_ptr);
2857 }
2858 }
2859 }
2860 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2861 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2862 hrrs.n_yielded(), r->rem_set()->occupied());
2863 r->rem_set()->clear_locked();
2864 }
2865 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2866 }
2867 _total_humongous++;
2868
2869 return false;
2870 }
2871
2872 size_t total_humongous() const { return _total_humongous; }
2873 size_t candidate_humongous() const { return _candidate_humongous; }
2874
2875 void flush_rem_set_entries() { _dcq.flush(); }
2876 };
2877
2878 void G1CollectedHeap::register_humongous_regions_with_cset() {
2879 if (!G1EagerReclaimHumongousObjects) {
2880 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2881 return;
2882 }
2883 double time = os::elapsed_counter();
2884
2885 // Collect reclaim candidate information and register candidates with cset.
2886 RegisterHumongousWithInCSetFastTestClosure cl;
2887 heap_region_iterate(&cl);
2888
2889 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2890 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2891 cl.total_humongous(),
2892 cl.candidate_humongous());
2893 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2894
2895 // Finally flush all remembered set entries to re-check into the global DCQS.
2896 cl.flush_rem_set_entries();
2897 }
2898
2899 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2900 public:
2901 bool doHeapRegion(HeapRegion* hr) {
2902 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2903 hr->verify_rem_set();
2904 }
2905 return false;
2906 }
2907 };
2908
2909 uint G1CollectedHeap::num_task_queues() const {
2910 return _task_queues->size();
2911 }
2912
2913 #if TASKQUEUE_STATS
2914 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2915 st->print_raw_cr("GC Task Stats");
2916 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2917 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2918 }
2919
2920 void G1CollectedHeap::print_taskqueue_stats() const {
2921 if (!log_is_enabled(Trace, gc, task, stats)) {
2922 return;
2923 }
2924 Log(gc, task, stats) log;
2925 ResourceMark rm;
2926 LogStream ls(log.trace());
2927 outputStream* st = &ls;
2928
2929 print_taskqueue_stats_hdr(st);
2930
2931 TaskQueueStats totals;
2932 const uint n = num_task_queues();
2933 for (uint i = 0; i < n; ++i) {
2934 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2935 totals += task_queue(i)->stats;
2936 }
2937 st->print_raw("tot "); totals.print(st); st->cr();
2938
2939 DEBUG_ONLY(totals.verify());
2940 }
2941
2942 void G1CollectedHeap::reset_taskqueue_stats() {
2943 const uint n = num_task_queues();
2944 for (uint i = 0; i < n; ++i) {
2945 task_queue(i)->stats.reset();
2946 }
2947 }
2948 #endif // TASKQUEUE_STATS
2949
2950 void G1CollectedHeap::wait_for_root_region_scanning() {
2951 double scan_wait_start = os::elapsedTime();
2952 // We have to wait until the CM threads finish scanning the
2953 // root regions as it's the only way to ensure that all the
2954 // objects on them have been correctly scanned before we start
2955 // moving them during the GC.
2956 bool waited = _cm->root_regions()->wait_until_scan_finished();
2957 double wait_time_ms = 0.0;
2958 if (waited) {
2959 double scan_wait_end = os::elapsedTime();
2960 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2961 }
2962 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2963 }
2964
2965 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2966 private:
2967 G1HRPrinter* _hr_printer;
2968 public:
2969 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2970
2971 virtual bool doHeapRegion(HeapRegion* r) {
2972 _hr_printer->cset(r);
2973 return false;
2974 }
2975 };
2976
2977 void G1CollectedHeap::start_new_collection_set() {
2978 collection_set()->start_incremental_building();
2979
2980 clear_cset_fast_test();
2981
2982 guarantee(_eden.length() == 0, "eden should have been cleared");
2983 g1_policy()->transfer_survivors_to_cset(survivor());
2984 }
2985
2986 bool
2987 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2988 assert_at_safepoint(true /* should_be_vm_thread */);
2989 guarantee(!is_gc_active(), "collection is not reentrant");
2990
2991 if (GCLocker::check_active_before_gc()) {
2992 return false;
2993 }
2994
2995 _gc_timer_stw->register_gc_start();
2996
2997 GCIdMark gc_id_mark;
2998 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2999
3000 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3001 ResourceMark rm;
3002
3003 g1_policy()->note_gc_start();
3004
3005 wait_for_root_region_scanning();
3006
3007 print_heap_before_gc();
3008 print_heap_regions();
3009 trace_heap_before_gc(_gc_tracer_stw);
3010
3011 _verifier->verify_region_sets_optional();
3012 _verifier->verify_dirty_young_regions();
3013
3014 // We should not be doing initial mark unless the conc mark thread is running
3015 if (!_cmThread->should_terminate()) {
3016 // This call will decide whether this pause is an initial-mark
3017 // pause. If it is, during_initial_mark_pause() will return true
3018 // for the duration of this pause.
3019 g1_policy()->decide_on_conc_mark_initiation();
3020 }
3021
3022 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3023 assert(!collector_state()->during_initial_mark_pause() ||
3024 collector_state()->gcs_are_young(), "sanity");
3025
3026 // We also do not allow mixed GCs during marking.
3027 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3028
3029 // Record whether this pause is an initial mark. When the current
3030 // thread has completed its logging output and it's safe to signal
3031 // the CM thread, the flag's value in the policy has been reset.
3032 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3033
3034 // Inner scope for scope based logging, timers, and stats collection
3035 {
3036 EvacuationInfo evacuation_info;
3037
3038 if (collector_state()->during_initial_mark_pause()) {
3039 // We are about to start a marking cycle, so we increment the
3040 // full collection counter.
3041 increment_old_marking_cycles_started();
3042 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3043 }
3044
3045 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3046
3047 GCTraceCPUTime tcpu;
3048
3049 FormatBuffer<> gc_string("Pause ");
3050 if (collector_state()->during_initial_mark_pause()) {
3051 gc_string.append("Initial Mark");
3052 } else if (collector_state()->gcs_are_young()) {
3053 gc_string.append("Young");
3054 } else {
3055 gc_string.append("Mixed");
3056 }
3057 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3058
3059 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3060 workers()->active_workers(),
3061 Threads::number_of_non_daemon_threads());
3062 workers()->update_active_workers(active_workers);
3063 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3064
3065 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3066 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3067
3068 // If the secondary_free_list is not empty, append it to the
3069 // free_list. No need to wait for the cleanup operation to finish;
3070 // the region allocation code will check the secondary_free_list
3071 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3072 // set, skip this step so that the region allocation code has to
3073 // get entries from the secondary_free_list.
3074 if (!G1StressConcRegionFreeing) {
3075 append_secondary_free_list_if_not_empty_with_lock();
3076 }
3077
3078 G1HeapTransition heap_transition(this);
3079 size_t heap_used_bytes_before_gc = used();
3080
3081 // Don't dynamically change the number of GC threads this early. A value of
3082 // 0 is used to indicate serial work. When parallel work is done,
3083 // it will be set.
3084
3085 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3086 IsGCActiveMark x;
3087
3088 gc_prologue(false);
3089 increment_total_collections(false /* full gc */);
3090 increment_gc_time_stamp();
3091
3092 if (VerifyRememberedSets) {
3093 log_info(gc, verify)("[Verifying RemSets before GC]");
3094 VerifyRegionRemSetClosure v_cl;
3095 heap_region_iterate(&v_cl);
3096 }
3097
3098 _verifier->verify_before_gc();
3099
3100 _verifier->check_bitmaps("GC Start");
3101
3102 #if defined(COMPILER2) || INCLUDE_JVMCI
3103 DerivedPointerTable::clear();
3104 #endif
3105
3106 // Please see comment in g1CollectedHeap.hpp and
3107 // G1CollectedHeap::ref_processing_init() to see how
3108 // reference processing currently works in G1.
3109
3110 // Enable discovery in the STW reference processor
3111 if (g1_policy()->should_process_references()) {
3112 ref_processor_stw()->enable_discovery();
3113 } else {
3114 ref_processor_stw()->disable_discovery();
3115 }
3116
3117 {
3118 // We want to temporarily turn off discovery by the
3119 // CM ref processor, if necessary, and turn it back on
3120 // on again later if we do. Using a scoped
3121 // NoRefDiscovery object will do this.
3122 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3123
3124 // Forget the current alloc region (we might even choose it to be part
3125 // of the collection set!).
3126 _allocator->release_mutator_alloc_region();
3127
3128 // This timing is only used by the ergonomics to handle our pause target.
3129 // It is unclear why this should not include the full pause. We will
3130 // investigate this in CR 7178365.
3131 //
3132 // Preserving the old comment here if that helps the investigation:
3133 //
3134 // The elapsed time induced by the start time below deliberately elides
3135 // the possible verification above.
3136 double sample_start_time_sec = os::elapsedTime();
3137
3138 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3139
3140 if (collector_state()->during_initial_mark_pause()) {
3141 concurrent_mark()->checkpointRootsInitialPre();
3142 }
3143
3144 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
3145
3146 evacuation_info.set_collectionset_regions(collection_set()->region_length());
3147
3148 // Make sure the remembered sets are up to date. This needs to be
3149 // done before register_humongous_regions_with_cset(), because the
3150 // remembered sets are used there to choose eager reclaim candidates.
3151 // If the remembered sets are not up to date we might miss some
3152 // entries that need to be handled.
3153 g1_rem_set()->cleanupHRRS();
3154
3155 register_humongous_regions_with_cset();
3156
3157 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3158
3159 // We call this after finalize_cset() to
3160 // ensure that the CSet has been finalized.
3161 _cm->verify_no_cset_oops();
3162
3163 if (_hr_printer.is_active()) {
3164 G1PrintCollectionSetClosure cl(&_hr_printer);
3165 _collection_set.iterate(&cl);
3166 }
3167
3168 // Initialize the GC alloc regions.
3169 _allocator->init_gc_alloc_regions(evacuation_info);
3170
3171 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
3172 pre_evacuate_collection_set();
3173
3174 // Actually do the work...
3175 evacuate_collection_set(evacuation_info, &per_thread_states);
3176
3177 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3178
3179 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3180 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3181
3182 eagerly_reclaim_humongous_regions();
3183
3184 record_obj_copy_mem_stats();
3185 _survivor_evac_stats.adjust_desired_plab_sz();
3186 _old_evac_stats.adjust_desired_plab_sz();
3187
3188 double start = os::elapsedTime();
3189 start_new_collection_set();
3190 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3191
3192 if (evacuation_failed()) {
3193 set_used(recalculate_used());
3194 if (_archive_allocator != NULL) {
3195 _archive_allocator->clear_used();
3196 }
3197 for (uint i = 0; i < ParallelGCThreads; i++) {
3198 if (_evacuation_failed_info_array[i].has_failed()) {
3199 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3200 }
3201 }
3202 } else {
3203 // The "used" of the the collection set have already been subtracted
3204 // when they were freed. Add in the bytes evacuated.
3205 increase_used(g1_policy()->bytes_copied_during_gc());
3206 }
3207
3208 if (collector_state()->during_initial_mark_pause()) {
3209 // We have to do this before we notify the CM threads that
3210 // they can start working to make sure that all the
3211 // appropriate initialization is done on the CM object.
3212 concurrent_mark()->checkpointRootsInitialPost();
3213 collector_state()->set_mark_in_progress(true);
3214 // Note that we don't actually trigger the CM thread at
3215 // this point. We do that later when we're sure that
3216 // the current thread has completed its logging output.
3217 }
3218
3219 allocate_dummy_regions();
3220
3221 _allocator->init_mutator_alloc_region();
3222
3223 {
3224 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3225 if (expand_bytes > 0) {
3226 size_t bytes_before = capacity();
3227 // No need for an ergo logging here,
3228 // expansion_amount() does this when it returns a value > 0.
3229 double expand_ms;
3230 if (!expand(expand_bytes, _workers, &expand_ms)) {
3231 // We failed to expand the heap. Cannot do anything about it.
3232 }
3233 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3234 }
3235 }
3236
3237 // We redo the verification but now wrt to the new CSet which
3238 // has just got initialized after the previous CSet was freed.
3239 _cm->verify_no_cset_oops();
3240
3241 // This timing is only used by the ergonomics to handle our pause target.
3242 // It is unclear why this should not include the full pause. We will
3243 // investigate this in CR 7178365.
3244 double sample_end_time_sec = os::elapsedTime();
3245 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3246 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
3247 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3248
3249 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3250 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3251
3252 MemoryService::track_memory_usage();
3253
3254 if (VerifyRememberedSets) {
3255 log_info(gc, verify)("[Verifying RemSets after GC]");
3256 VerifyRegionRemSetClosure v_cl;
3257 heap_region_iterate(&v_cl);
3258 }
3259
3260 _verifier->verify_after_gc();
3261 _verifier->check_bitmaps("GC End");
3262
3263 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3264 ref_processor_stw()->verify_no_references_recorded();
3265
3266 // CM reference discovery will be re-enabled if necessary.
3267 }
3268
3269 #ifdef TRACESPINNING
3270 ParallelTaskTerminator::print_termination_counts();
3271 #endif
3272
3273 gc_epilogue(false);
3274 }
3275
3276 // Print the remainder of the GC log output.
3277 if (evacuation_failed()) {
3278 log_info(gc)("To-space exhausted");
3279 }
3280
3281 g1_policy()->print_phases();
3282 heap_transition.print();
3283
3284 // It is not yet to safe to tell the concurrent mark to
3285 // start as we have some optional output below. We don't want the
3286 // output from the concurrent mark thread interfering with this
3287 // logging output either.
3288
3289 _hrm.verify_optional();
3290 _verifier->verify_region_sets_optional();
3291
3292 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3293 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3294
3295 print_heap_after_gc();
3296 print_heap_regions();
3297 trace_heap_after_gc(_gc_tracer_stw);
3298
3299 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3300 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3301 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3302 // before any GC notifications are raised.
3303 g1mm()->update_sizes();
3304
3305 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3306 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3307 _gc_timer_stw->register_gc_end();
3308 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3309 }
3310 // It should now be safe to tell the concurrent mark thread to start
3311 // without its logging output interfering with the logging output
3312 // that came from the pause.
3313
3314 if (should_start_conc_mark) {
3315 // CAUTION: after the doConcurrentMark() call below,
3316 // the concurrent marking thread(s) could be running
3317 // concurrently with us. Make sure that anything after
3318 // this point does not assume that we are the only GC thread
3319 // running. Note: of course, the actual marking work will
3320 // not start until the safepoint itself is released in
3321 // SuspendibleThreadSet::desynchronize().
3322 doConcurrentMark();
3323 }
3324
3325 return true;
3326 }
3327
3328 void G1CollectedHeap::remove_self_forwarding_pointers() {
3329 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3330 workers()->run_task(&rsfp_task);
3331 }
3332
3333 void G1CollectedHeap::restore_after_evac_failure() {
3334 double remove_self_forwards_start = os::elapsedTime();
3335
3336 remove_self_forwarding_pointers();
3337 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3338 _preserved_marks_set.restore(&task_executor);
3339
3340 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3341 }
3342
3343 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3344 if (!_evacuation_failed) {
3345 _evacuation_failed = true;
3346 }
3347
3348 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3349 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3350 }
3351
3352 bool G1ParEvacuateFollowersClosure::offer_termination() {
3353 G1ParScanThreadState* const pss = par_scan_state();
3354 start_term_time();
3355 const bool res = terminator()->offer_termination();
3356 end_term_time();
3357 return res;
3358 }
3359
3360 void G1ParEvacuateFollowersClosure::do_void() {
3361 G1ParScanThreadState* const pss = par_scan_state();
3362 pss->trim_queue();
3363 do {
3364 pss->steal_and_trim_queue(queues());
3365 } while (!offer_termination());
3366 }
3367
3368 class G1ParTask : public AbstractGangTask {
3369 protected:
3370 G1CollectedHeap* _g1h;
3371 G1ParScanThreadStateSet* _pss;
3372 RefToScanQueueSet* _queues;
3373 G1RootProcessor* _root_processor;
3374 ParallelTaskTerminator _terminator;
3375 uint _n_workers;
3376
3377 public:
3378 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3379 : AbstractGangTask("G1 collection"),
3380 _g1h(g1h),
3381 _pss(per_thread_states),
3382 _queues(task_queues),
3383 _root_processor(root_processor),
3384 _terminator(n_workers, _queues),
3385 _n_workers(n_workers)
3386 {}
3387
3388 void work(uint worker_id) {
3389 if (worker_id >= _n_workers) return; // no work needed this round
3390
3391 double start_sec = os::elapsedTime();
3392 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3393
3394 {
3395 ResourceMark rm;
3396 HandleMark hm;
3397
3398 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3399
3400 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3401 pss->set_ref_processor(rp);
3402
3403 double start_strong_roots_sec = os::elapsedTime();
3404
3405 _root_processor->evacuate_roots(pss->closures(), worker_id);
3406
3407 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3408 // treating the nmethods visited to act as roots for concurrent marking.
3409 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3410 // objects copied by the current evacuation.
3411 _g1h->g1_rem_set()->oops_into_collection_set_do(pss,
3412 pss->closures()->weak_codeblobs(),
3413 worker_id);
3414
3415 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3416
3417 double term_sec = 0.0;
3418 size_t evac_term_attempts = 0;
3419 {
3420 double start = os::elapsedTime();
3421 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3422 evac.do_void();
3423
3424 evac_term_attempts = evac.term_attempts();
3425 term_sec = evac.term_time();
3426 double elapsed_sec = os::elapsedTime() - start;
3427 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3428 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3429 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3430 }
3431
3432 assert(pss->queue_is_empty(), "should be empty");
3433
3434 if (log_is_enabled(Debug, gc, task, stats)) {
3435 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3436 size_t lab_waste;
3437 size_t lab_undo_waste;
3438 pss->waste(lab_waste, lab_undo_waste);
3439 _g1h->print_termination_stats(worker_id,
3440 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3441 strong_roots_sec * 1000.0, /* strong roots time */
3442 term_sec * 1000.0, /* evac term time */
3443 evac_term_attempts, /* evac term attempts */
3444 lab_waste, /* alloc buffer waste */
3445 lab_undo_waste /* undo waste */
3446 );
3447 }
3448
3449 // Close the inner scope so that the ResourceMark and HandleMark
3450 // destructors are executed here and are included as part of the
3451 // "GC Worker Time".
3452 }
3453 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3454 }
3455 };
3456
3457 void G1CollectedHeap::print_termination_stats_hdr() {
3458 log_debug(gc, task, stats)("GC Termination Stats");
3459 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3460 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3461 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3462 }
3463
3464 void G1CollectedHeap::print_termination_stats(uint worker_id,
3465 double elapsed_ms,
3466 double strong_roots_ms,
3467 double term_ms,
3468 size_t term_attempts,
3469 size_t alloc_buffer_waste,
3470 size_t undo_waste) const {
3471 log_debug(gc, task, stats)
3472 ("%3d %9.2f %9.2f %6.2f "
3473 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3474 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3475 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3476 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3477 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3478 alloc_buffer_waste * HeapWordSize / K,
3479 undo_waste * HeapWordSize / K);
3480 }
3481
3482 class G1StringAndSymbolCleaningTask : public AbstractGangTask {
3483 private:
3484 BoolObjectClosure* _is_alive;
3485 G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
3486
3487 int _initial_string_table_size;
3488 int _initial_symbol_table_size;
3489
3490 bool _process_strings;
3491 int _strings_processed;
3492 int _strings_removed;
3493
3494 bool _process_symbols;
3495 int _symbols_processed;
3496 int _symbols_removed;
3497
3498 bool _process_string_dedup;
3499
3500 public:
3501 G1StringAndSymbolCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool process_string_dedup) :
3502 AbstractGangTask("String/Symbol Unlinking"),
3503 _is_alive(is_alive),
3504 _dedup_closure(is_alive, NULL, false),
3505 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3506 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0),
3507 _process_string_dedup(process_string_dedup) {
3508
3509 _initial_string_table_size = StringTable::the_table()->table_size();
3510 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3511 if (process_strings) {
3512 StringTable::clear_parallel_claimed_index();
3513 }
3514 if (process_symbols) {
3515 SymbolTable::clear_parallel_claimed_index();
3516 }
3517 }
3518
3519 ~G1StringAndSymbolCleaningTask() {
3520 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3521 "claim value %d after unlink less than initial string table size %d",
3522 StringTable::parallel_claimed_index(), _initial_string_table_size);
3523 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3524 "claim value %d after unlink less than initial symbol table size %d",
3525 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3526
3527 log_info(gc, stringtable)(
3528 "Cleaned string and symbol table, "
3529 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3530 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3531 strings_processed(), strings_removed(),
3532 symbols_processed(), symbols_removed());
3533 }
3534
3535 void work(uint worker_id) {
3536 int strings_processed = 0;
3537 int strings_removed = 0;
3538 int symbols_processed = 0;
3539 int symbols_removed = 0;
3540 if (_process_strings) {
3541 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3542 Atomic::add(strings_processed, &_strings_processed);
3543 Atomic::add(strings_removed, &_strings_removed);
3544 }
3545 if (_process_symbols) {
3546 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3547 Atomic::add(symbols_processed, &_symbols_processed);
3548 Atomic::add(symbols_removed, &_symbols_removed);
3549 }
3550 if (_process_string_dedup) {
3551 G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
3552 }
3553 }
3554
3555 size_t strings_processed() const { return (size_t)_strings_processed; }
3556 size_t strings_removed() const { return (size_t)_strings_removed; }
3557
3558 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3559 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3560 };
3561
3562 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3563 private:
3564 static Monitor* _lock;
3565
3566 BoolObjectClosure* const _is_alive;
3567 const bool _unloading_occurred;
3568 const uint _num_workers;
3569
3570 // Variables used to claim nmethods.
3571 CompiledMethod* _first_nmethod;
3572 volatile CompiledMethod* _claimed_nmethod;
3573
3574 // The list of nmethods that need to be processed by the second pass.
3575 volatile CompiledMethod* _postponed_list;
3576 volatile uint _num_entered_barrier;
3577
3578 public:
3579 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3580 _is_alive(is_alive),
3581 _unloading_occurred(unloading_occurred),
3582 _num_workers(num_workers),
3583 _first_nmethod(NULL),
3584 _claimed_nmethod(NULL),
3585 _postponed_list(NULL),
3586 _num_entered_barrier(0)
3587 {
3588 CompiledMethod::increase_unloading_clock();
3589 // Get first alive nmethod
3590 CompiledMethodIterator iter = CompiledMethodIterator();
3591 if(iter.next_alive()) {
3592 _first_nmethod = iter.method();
3593 }
3594 _claimed_nmethod = (volatile CompiledMethod*)_first_nmethod;
3595 }
3596
3597 ~G1CodeCacheUnloadingTask() {
3598 CodeCache::verify_clean_inline_caches();
3599
3600 CodeCache::set_needs_cache_clean(false);
3601 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3602
3603 CodeCache::verify_icholder_relocations();
3604 }
3605
3606 private:
3607 void add_to_postponed_list(CompiledMethod* nm) {
3608 CompiledMethod* old;
3609 do {
3610 old = (CompiledMethod*)_postponed_list;
3611 nm->set_unloading_next(old);
3612 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3613 }
3614
3615 void clean_nmethod(CompiledMethod* nm) {
3616 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3617
3618 if (postponed) {
3619 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3620 add_to_postponed_list(nm);
3621 }
3622
3623 // Mark that this thread has been cleaned/unloaded.
3624 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3625 nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
3626 }
3627
3628 void clean_nmethod_postponed(CompiledMethod* nm) {
3629 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3630 }
3631
3632 static const int MaxClaimNmethods = 16;
3633
3634 void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
3635 CompiledMethod* first;
3636 CompiledMethodIterator last;
3637
3638 do {
3639 *num_claimed_nmethods = 0;
3640
3641 first = (CompiledMethod*)_claimed_nmethod;
3642 last = CompiledMethodIterator(first);
3643
3644 if (first != NULL) {
3645
3646 for (int i = 0; i < MaxClaimNmethods; i++) {
3647 if (!last.next_alive()) {
3648 break;
3649 }
3650 claimed_nmethods[i] = last.method();
3651 (*num_claimed_nmethods)++;
3652 }
3653 }
3654
3655 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3656 }
3657
3658 CompiledMethod* claim_postponed_nmethod() {
3659 CompiledMethod* claim;
3660 CompiledMethod* next;
3661
3662 do {
3663 claim = (CompiledMethod*)_postponed_list;
3664 if (claim == NULL) {
3665 return NULL;
3666 }
3667
3668 next = claim->unloading_next();
3669
3670 } while ((CompiledMethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3671
3672 return claim;
3673 }
3674
3675 public:
3676 // Mark that we're done with the first pass of nmethod cleaning.
3677 void barrier_mark(uint worker_id) {
3678 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3679 _num_entered_barrier++;
3680 if (_num_entered_barrier == _num_workers) {
3681 ml.notify_all();
3682 }
3683 }
3684
3685 // See if we have to wait for the other workers to
3686 // finish their first-pass nmethod cleaning work.
3687 void barrier_wait(uint worker_id) {
3688 if (_num_entered_barrier < _num_workers) {
3689 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3690 while (_num_entered_barrier < _num_workers) {
3691 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3692 }
3693 }
3694 }
3695
3696 // Cleaning and unloading of nmethods. Some work has to be postponed
3697 // to the second pass, when we know which nmethods survive.
3698 void work_first_pass(uint worker_id) {
3699 // The first nmethods is claimed by the first worker.
3700 if (worker_id == 0 && _first_nmethod != NULL) {
3701 clean_nmethod(_first_nmethod);
3702 _first_nmethod = NULL;
3703 }
3704
3705 int num_claimed_nmethods;
3706 CompiledMethod* claimed_nmethods[MaxClaimNmethods];
3707
3708 while (true) {
3709 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3710
3711 if (num_claimed_nmethods == 0) {
3712 break;
3713 }
3714
3715 for (int i = 0; i < num_claimed_nmethods; i++) {
3716 clean_nmethod(claimed_nmethods[i]);
3717 }
3718 }
3719 }
3720
3721 void work_second_pass(uint worker_id) {
3722 CompiledMethod* nm;
3723 // Take care of postponed nmethods.
3724 while ((nm = claim_postponed_nmethod()) != NULL) {
3725 clean_nmethod_postponed(nm);
3726 }
3727 }
3728 };
3729
3730 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3731
3732 class G1KlassCleaningTask : public StackObj {
3733 BoolObjectClosure* _is_alive;
3734 volatile jint _clean_klass_tree_claimed;
3735 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3736
3737 public:
3738 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3739 _is_alive(is_alive),
3740 _clean_klass_tree_claimed(0),
3741 _klass_iterator() {
3742 }
3743
3744 private:
3745 bool claim_clean_klass_tree_task() {
3746 if (_clean_klass_tree_claimed) {
3747 return false;
3748 }
3749
3750 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
3751 }
3752
3753 InstanceKlass* claim_next_klass() {
3754 Klass* klass;
3755 do {
3756 klass =_klass_iterator.next_klass();
3757 } while (klass != NULL && !klass->is_instance_klass());
3758
3759 // this can be null so don't call InstanceKlass::cast
3760 return static_cast<InstanceKlass*>(klass);
3761 }
3762
3763 public:
3764
3765 void clean_klass(InstanceKlass* ik) {
3766 ik->clean_weak_instanceklass_links(_is_alive);
3767 }
3768
3769 void work() {
3770 ResourceMark rm;
3771
3772 // One worker will clean the subklass/sibling klass tree.
3773 if (claim_clean_klass_tree_task()) {
3774 Klass::clean_subklass_tree(_is_alive);
3775 }
3776
3777 // All workers will help cleaning the classes,
3778 InstanceKlass* klass;
3779 while ((klass = claim_next_klass()) != NULL) {
3780 clean_klass(klass);
3781 }
3782 }
3783 };
3784
3785 class G1ResolvedMethodCleaningTask : public StackObj {
3786 BoolObjectClosure* _is_alive;
3787 volatile jint _resolved_method_task_claimed;
3788 public:
3789 G1ResolvedMethodCleaningTask(BoolObjectClosure* is_alive) :
3790 _is_alive(is_alive), _resolved_method_task_claimed(0) {}
3791
3792 bool claim_resolved_method_task() {
3793 if (_resolved_method_task_claimed) {
3794 return false;
3795 }
3796 return Atomic::cmpxchg(1, (jint*)&_resolved_method_task_claimed, 0) == 0;
3797 }
3798
3799 // These aren't big, one thread can do it all.
3800 void work() {
3801 if (claim_resolved_method_task()) {
3802 ResolvedMethodTable::unlink(_is_alive);
3803 }
3804 }
3805 };
3806
3807
3808 // To minimize the remark pause times, the tasks below are done in parallel.
3809 class G1ParallelCleaningTask : public AbstractGangTask {
3810 private:
3811 G1StringAndSymbolCleaningTask _string_symbol_task;
3812 G1CodeCacheUnloadingTask _code_cache_task;
3813 G1KlassCleaningTask _klass_cleaning_task;
3814 G1ResolvedMethodCleaningTask _resolved_method_cleaning_task;
3815
3816 public:
3817 // The constructor is run in the VMThread.
3818 G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
3819 AbstractGangTask("Parallel Cleaning"),
3820 _string_symbol_task(is_alive, true, true, G1StringDedup::is_enabled()),
3821 _code_cache_task(num_workers, is_alive, unloading_occurred),
3822 _klass_cleaning_task(is_alive),
3823 _resolved_method_cleaning_task(is_alive) {
3824 }
3825
3826 // The parallel work done by all worker threads.
3827 void work(uint worker_id) {
3828 // Do first pass of code cache cleaning.
3829 _code_cache_task.work_first_pass(worker_id);
3830
3831 // Let the threads mark that the first pass is done.
3832 _code_cache_task.barrier_mark(worker_id);
3833
3834 // Clean the Strings and Symbols.
3835 _string_symbol_task.work(worker_id);
3836
3837 // Clean unreferenced things in the ResolvedMethodTable
3838 _resolved_method_cleaning_task.work();
3839
3840 // Wait for all workers to finish the first code cache cleaning pass.
3841 _code_cache_task.barrier_wait(worker_id);
3842
3843 // Do the second code cache cleaning work, which realize on
3844 // the liveness information gathered during the first pass.
3845 _code_cache_task.work_second_pass(worker_id);
3846
3847 // Clean all klasses that were not unloaded.
3848 _klass_cleaning_task.work();
3849 }
3850 };
3851
3852
3853 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3854 bool class_unloading_occurred) {
3855 uint n_workers = workers()->active_workers();
3856
3857 G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
3858 workers()->run_task(&g1_unlink_task);
3859 }
3860
3861 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3862 bool process_strings,
3863 bool process_symbols,
3864 bool process_string_dedup) {
3865 if (!process_strings && !process_symbols && !process_string_dedup) {
3866 // Nothing to clean.
3867 return;
3868 }
3869
3870 G1StringAndSymbolCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols, process_string_dedup);
3871 workers()->run_task(&g1_unlink_task);
3872
3873 }
3874
3875 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3876 private:
3877 DirtyCardQueueSet* _queue;
3878 G1CollectedHeap* _g1h;
3879 public:
3880 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3881 _queue(queue), _g1h(g1h) { }
3882
3883 virtual void work(uint worker_id) {
3884 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3885 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3886
3887 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3888 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3889
3890 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3891 }
3892 };
3893
3894 void G1CollectedHeap::redirty_logged_cards() {
3895 double redirty_logged_cards_start = os::elapsedTime();
3896
3897 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3898 dirty_card_queue_set().reset_for_par_iteration();
3899 workers()->run_task(&redirty_task);
3900
3901 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
3902 dcq.merge_bufferlists(&dirty_card_queue_set());
3903 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3904
3905 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3906 }
3907
3908 // Weak Reference Processing support
3909
3910 // An always "is_alive" closure that is used to preserve referents.
3911 // If the object is non-null then it's alive. Used in the preservation
3912 // of referent objects that are pointed to by reference objects
3913 // discovered by the CM ref processor.
3914 class G1AlwaysAliveClosure: public BoolObjectClosure {
3915 G1CollectedHeap* _g1;
3916 public:
3917 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3918 bool do_object_b(oop p) {
3919 if (p != NULL) {
3920 return true;
3921 }
3922 return false;
3923 }
3924 };
3925
3926 bool G1STWIsAliveClosure::do_object_b(oop p) {
3927 // An object is reachable if it is outside the collection set,
3928 // or is inside and copied.
3929 return !_g1->is_in_cset(p) || p->is_forwarded();
3930 }
3931
3932 // Non Copying Keep Alive closure
3933 class G1KeepAliveClosure: public OopClosure {
3934 G1CollectedHeap* _g1;
3935 public:
3936 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3937 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3938 void do_oop(oop* p) {
3939 oop obj = *p;
3940 assert(obj != NULL, "the caller should have filtered out NULL values");
3941
3942 const InCSetState cset_state = _g1->in_cset_state(obj);
3943 if (!cset_state.is_in_cset_or_humongous()) {
3944 return;
3945 }
3946 if (cset_state.is_in_cset()) {
3947 assert( obj->is_forwarded(), "invariant" );
3948 *p = obj->forwardee();
3949 } else {
3950 assert(!obj->is_forwarded(), "invariant" );
3951 assert(cset_state.is_humongous(),
3952 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3953 _g1->set_humongous_is_live(obj);
3954 }
3955 }
3956 };
3957
3958 // Copying Keep Alive closure - can be called from both
3959 // serial and parallel code as long as different worker
3960 // threads utilize different G1ParScanThreadState instances
3961 // and different queues.
3962
3963 class G1CopyingKeepAliveClosure: public OopClosure {
3964 G1CollectedHeap* _g1h;
3965 OopClosure* _copy_non_heap_obj_cl;
3966 G1ParScanThreadState* _par_scan_state;
3967
3968 public:
3969 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3970 OopClosure* non_heap_obj_cl,
3971 G1ParScanThreadState* pss):
3972 _g1h(g1h),
3973 _copy_non_heap_obj_cl(non_heap_obj_cl),
3974 _par_scan_state(pss)
3975 {}
3976
3977 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3978 virtual void do_oop( oop* p) { do_oop_work(p); }
3979
3980 template <class T> void do_oop_work(T* p) {
3981 oop obj = oopDesc::load_decode_heap_oop(p);
3982
3983 if (_g1h->is_in_cset_or_humongous(obj)) {
3984 // If the referent object has been forwarded (either copied
3985 // to a new location or to itself in the event of an
3986 // evacuation failure) then we need to update the reference
3987 // field and, if both reference and referent are in the G1
3988 // heap, update the RSet for the referent.
3989 //
3990 // If the referent has not been forwarded then we have to keep
3991 // it alive by policy. Therefore we have copy the referent.
3992 //
3993 // If the reference field is in the G1 heap then we can push
3994 // on the PSS queue. When the queue is drained (after each
3995 // phase of reference processing) the object and it's followers
3996 // will be copied, the reference field set to point to the
3997 // new location, and the RSet updated. Otherwise we need to
3998 // use the the non-heap or metadata closures directly to copy
3999 // the referent object and update the pointer, while avoiding
4000 // updating the RSet.
4001
4002 if (_g1h->is_in_g1_reserved(p)) {
4003 _par_scan_state->push_on_queue(p);
4004 } else {
4005 assert(!Metaspace::contains((const void*)p),
4006 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4007 _copy_non_heap_obj_cl->do_oop(p);
4008 }
4009 }
4010 }
4011 };
4012
4013 // Serial drain queue closure. Called as the 'complete_gc'
4014 // closure for each discovered list in some of the
4015 // reference processing phases.
4016
4017 class G1STWDrainQueueClosure: public VoidClosure {
4018 protected:
4019 G1CollectedHeap* _g1h;
4020 G1ParScanThreadState* _par_scan_state;
4021
4022 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4023
4024 public:
4025 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4026 _g1h(g1h),
4027 _par_scan_state(pss)
4028 { }
4029
4030 void do_void() {
4031 G1ParScanThreadState* const pss = par_scan_state();
4032 pss->trim_queue();
4033 }
4034 };
4035
4036 // Parallel Reference Processing closures
4037
4038 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4039 // processing during G1 evacuation pauses.
4040
4041 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4042 private:
4043 G1CollectedHeap* _g1h;
4044 G1ParScanThreadStateSet* _pss;
4045 RefToScanQueueSet* _queues;
4046 WorkGang* _workers;
4047 uint _active_workers;
4048
4049 public:
4050 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4051 G1ParScanThreadStateSet* per_thread_states,
4052 WorkGang* workers,
4053 RefToScanQueueSet *task_queues,
4054 uint n_workers) :
4055 _g1h(g1h),
4056 _pss(per_thread_states),
4057 _queues(task_queues),
4058 _workers(workers),
4059 _active_workers(n_workers)
4060 {
4061 g1h->ref_processor_stw()->set_active_mt_degree(n_workers);
4062 }
4063
4064 // Executes the given task using concurrent marking worker threads.
4065 virtual void execute(ProcessTask& task);
4066 virtual void execute(EnqueueTask& task);
4067 };
4068
4069 // Gang task for possibly parallel reference processing
4070
4071 class G1STWRefProcTaskProxy: public AbstractGangTask {
4072 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4073 ProcessTask& _proc_task;
4074 G1CollectedHeap* _g1h;
4075 G1ParScanThreadStateSet* _pss;
4076 RefToScanQueueSet* _task_queues;
4077 ParallelTaskTerminator* _terminator;
4078
4079 public:
4080 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4081 G1CollectedHeap* g1h,
4082 G1ParScanThreadStateSet* per_thread_states,
4083 RefToScanQueueSet *task_queues,
4084 ParallelTaskTerminator* terminator) :
4085 AbstractGangTask("Process reference objects in parallel"),
4086 _proc_task(proc_task),
4087 _g1h(g1h),
4088 _pss(per_thread_states),
4089 _task_queues(task_queues),
4090 _terminator(terminator)
4091 {}
4092
4093 virtual void work(uint worker_id) {
4094 // The reference processing task executed by a single worker.
4095 ResourceMark rm;
4096 HandleMark hm;
4097
4098 G1STWIsAliveClosure is_alive(_g1h);
4099
4100 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4101 pss->set_ref_processor(NULL);
4102
4103 // Keep alive closure.
4104 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4105
4106 // Complete GC closure
4107 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4108
4109 // Call the reference processing task's work routine.
4110 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4111
4112 // Note we cannot assert that the refs array is empty here as not all
4113 // of the processing tasks (specifically phase2 - pp2_work) execute
4114 // the complete_gc closure (which ordinarily would drain the queue) so
4115 // the queue may not be empty.
4116 }
4117 };
4118
4119 // Driver routine for parallel reference processing.
4120 // Creates an instance of the ref processing gang
4121 // task and has the worker threads execute it.
4122 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4123 assert(_workers != NULL, "Need parallel worker threads.");
4124
4125 ParallelTaskTerminator terminator(_active_workers, _queues);
4126 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4127
4128 _workers->run_task(&proc_task_proxy);
4129 }
4130
4131 // Gang task for parallel reference enqueueing.
4132
4133 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4134 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4135 EnqueueTask& _enq_task;
4136
4137 public:
4138 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4139 AbstractGangTask("Enqueue reference objects in parallel"),
4140 _enq_task(enq_task)
4141 { }
4142
4143 virtual void work(uint worker_id) {
4144 _enq_task.work(worker_id);
4145 }
4146 };
4147
4148 // Driver routine for parallel reference enqueueing.
4149 // Creates an instance of the ref enqueueing gang
4150 // task and has the worker threads execute it.
4151
4152 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4153 assert(_workers != NULL, "Need parallel worker threads.");
4154
4155 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4156
4157 _workers->run_task(&enq_task_proxy);
4158 }
4159
4160 // End of weak reference support closures
4161
4162 // Abstract task used to preserve (i.e. copy) any referent objects
4163 // that are in the collection set and are pointed to by reference
4164 // objects discovered by the CM ref processor.
4165
4166 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4167 protected:
4168 G1CollectedHeap* _g1h;
4169 G1ParScanThreadStateSet* _pss;
4170 RefToScanQueueSet* _queues;
4171 ParallelTaskTerminator _terminator;
4172 uint _n_workers;
4173
4174 public:
4175 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4176 AbstractGangTask("ParPreserveCMReferents"),
4177 _g1h(g1h),
4178 _pss(per_thread_states),
4179 _queues(task_queues),
4180 _terminator(workers, _queues),
4181 _n_workers(workers)
4182 {
4183 g1h->ref_processor_cm()->set_active_mt_degree(workers);
4184 }
4185
4186 void work(uint worker_id) {
4187 G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
4188
4189 ResourceMark rm;
4190 HandleMark hm;
4191
4192 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4193 pss->set_ref_processor(NULL);
4194 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4195
4196 // Is alive closure
4197 G1AlwaysAliveClosure always_alive(_g1h);
4198
4199 // Copying keep alive closure. Applied to referent objects that need
4200 // to be copied.
4201 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4202
4203 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4204
4205 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4206 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4207
4208 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4209 // So this must be true - but assert just in case someone decides to
4210 // change the worker ids.
4211 assert(worker_id < limit, "sanity");
4212 assert(!rp->discovery_is_atomic(), "check this code");
4213
4214 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4215 for (uint idx = worker_id; idx < limit; idx += stride) {
4216 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4217
4218 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4219 while (iter.has_next()) {
4220 // Since discovery is not atomic for the CM ref processor, we
4221 // can see some null referent objects.
4222 iter.load_ptrs(DEBUG_ONLY(true));
4223 oop ref = iter.obj();
4224
4225 // This will filter nulls.
4226 if (iter.is_referent_alive()) {
4227 iter.make_referent_alive();
4228 }
4229 iter.move_to_next();
4230 }
4231 }
4232
4233 // Drain the queue - which may cause stealing
4234 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4235 drain_queue.do_void();
4236 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4237 assert(pss->queue_is_empty(), "should be");
4238 }
4239 };
4240
4241 void G1CollectedHeap::process_weak_jni_handles() {
4242 double ref_proc_start = os::elapsedTime();
4243
4244 G1STWIsAliveClosure is_alive(this);
4245 G1KeepAliveClosure keep_alive(this);
4246 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4247
4248 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4249 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4250 }
4251
4252 void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
4253 // Any reference objects, in the collection set, that were 'discovered'
4254 // by the CM ref processor should have already been copied (either by
4255 // applying the external root copy closure to the discovered lists, or
4256 // by following an RSet entry).
4257 //
4258 // But some of the referents, that are in the collection set, that these
4259 // reference objects point to may not have been copied: the STW ref
4260 // processor would have seen that the reference object had already
4261 // been 'discovered' and would have skipped discovering the reference,
4262 // but would not have treated the reference object as a regular oop.
4263 // As a result the copy closure would not have been applied to the
4264 // referent object.
4265 //
4266 // We need to explicitly copy these referent objects - the references
4267 // will be processed at the end of remarking.
4268 //
4269 // We also need to do this copying before we process the reference
4270 // objects discovered by the STW ref processor in case one of these
4271 // referents points to another object which is also referenced by an
4272 // object discovered by the STW ref processor.
4273 double preserve_cm_referents_time = 0.0;
4274
4275 // To avoid spawning task when there is no work to do, check that
4276 // a concurrent cycle is active and that some references have been
4277 // discovered.
4278 if (concurrent_mark()->cmThread()->during_cycle() &&
4279 ref_processor_cm()->has_discovered_references()) {
4280 double preserve_cm_referents_start = os::elapsedTime();
4281 uint no_of_gc_workers = workers()->active_workers();
4282 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4283 per_thread_states,
4284 no_of_gc_workers,
4285 _task_queues);
4286 workers()->run_task(&keep_cm_referents);
4287 preserve_cm_referents_time = os::elapsedTime() - preserve_cm_referents_start;
4288 }
4289
4290 g1_policy()->phase_times()->record_preserve_cm_referents_time_ms(preserve_cm_referents_time * 1000.0);
4291 }
4292
4293 // Weak Reference processing during an evacuation pause (part 1).
4294 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4295 double ref_proc_start = os::elapsedTime();
4296
4297 ReferenceProcessor* rp = _ref_processor_stw;
4298 assert(rp->discovery_enabled(), "should have been enabled");
4299
4300 // Closure to test whether a referent is alive.
4301 G1STWIsAliveClosure is_alive(this);
4302
4303 // Even when parallel reference processing is enabled, the processing
4304 // of JNI refs is serial and performed serially by the current thread
4305 // rather than by a worker. The following PSS will be used for processing
4306 // JNI refs.
4307
4308 // Use only a single queue for this PSS.
4309 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4310 pss->set_ref_processor(NULL);
4311 assert(pss->queue_is_empty(), "pre-condition");
4312
4313 // Keep alive closure.
4314 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4315
4316 // Serial Complete GC closure
4317 G1STWDrainQueueClosure drain_queue(this, pss);
4318
4319 // Setup the soft refs policy...
4320 rp->setup_policy(false);
4321
4322 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4323
4324 ReferenceProcessorStats stats;
4325 if (!rp->processing_is_mt()) {
4326 // Serial reference processing...
4327 stats = rp->process_discovered_references(&is_alive,
4328 &keep_alive,
4329 &drain_queue,
4330 NULL,
4331 pt);
4332 } else {
4333 uint no_of_gc_workers = workers()->active_workers();
4334
4335 // Parallel reference processing
4336 assert(no_of_gc_workers <= rp->max_num_q(),
4337 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4338 no_of_gc_workers, rp->max_num_q());
4339
4340 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4341 stats = rp->process_discovered_references(&is_alive,
4342 &keep_alive,
4343 &drain_queue,
4344 &par_task_executor,
4345 pt);
4346 }
4347
4348 _gc_tracer_stw->report_gc_reference_stats(stats);
4349
4350 // We have completed copying any necessary live referent objects.
4351 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4352
4353 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4354 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4355 }
4356
4357 // Weak Reference processing during an evacuation pause (part 2).
4358 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4359 double ref_enq_start = os::elapsedTime();
4360
4361 ReferenceProcessor* rp = _ref_processor_stw;
4362 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4363
4364 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
4365
4366 // Now enqueue any remaining on the discovered lists on to
4367 // the pending list.
4368 if (!rp->processing_is_mt()) {
4369 // Serial reference processing...
4370 rp->enqueue_discovered_references(NULL, pt);
4371 } else {
4372 // Parallel reference enqueueing
4373
4374 uint n_workers = workers()->active_workers();
4375
4376 assert(n_workers <= rp->max_num_q(),
4377 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
4378 n_workers, rp->max_num_q());
4379
4380 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4381 rp->enqueue_discovered_references(&par_task_executor, pt);
4382 }
4383
4384 rp->verify_no_references_recorded();
4385 assert(!rp->discovery_enabled(), "should have been disabled");
4386
4387 // FIXME
4388 // CM's reference processing also cleans up the string and symbol tables.
4389 // Should we do that here also? We could, but it is a serial operation
4390 // and could significantly increase the pause time.
4391
4392 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4393 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4394 }
4395
4396 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
4397 double merge_pss_time_start = os::elapsedTime();
4398 per_thread_states->flush();
4399 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
4400 }
4401
4402 void G1CollectedHeap::pre_evacuate_collection_set() {
4403 _expand_heap_after_alloc_failure = true;
4404 _evacuation_failed = false;
4405
4406 // Disable the hot card cache.
4407 _hot_card_cache->reset_hot_cache_claimed_index();
4408 _hot_card_cache->set_use_cache(false);
4409
4410 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4411 _preserved_marks_set.assert_empty();
4412
4413 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4414
4415 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4416 if (collector_state()->during_initial_mark_pause()) {
4417 double start_clear_claimed_marks = os::elapsedTime();
4418
4419 ClassLoaderDataGraph::clear_claimed_marks();
4420
4421 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
4422 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
4423 }
4424 }
4425
4426 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4427 // Should G1EvacuationFailureALot be in effect for this GC?
4428 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4429
4430 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4431
4432 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4433
4434 double start_par_time_sec = os::elapsedTime();
4435 double end_par_time_sec;
4436
4437 {
4438 const uint n_workers = workers()->active_workers();
4439 G1RootProcessor root_processor(this, n_workers);
4440 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4441
4442 print_termination_stats_hdr();
4443
4444 workers()->run_task(&g1_par_task);
4445 end_par_time_sec = os::elapsedTime();
4446
4447 // Closing the inner scope will execute the destructor
4448 // for the G1RootProcessor object. We record the current
4449 // elapsed time before closing the scope so that time
4450 // taken for the destructor is NOT included in the
4451 // reported parallel time.
4452 }
4453
4454 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4455 phase_times->record_par_time(par_time_ms);
4456
4457 double code_root_fixup_time_ms =
4458 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4459 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4460 }
4461
4462 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4463 // Process any discovered reference objects - we have
4464 // to do this _before_ we retire the GC alloc regions
4465 // as we may have to copy some 'reachable' referent
4466 // objects (and their reachable sub-graphs) that were
4467 // not copied during the pause.
4468 if (g1_policy()->should_process_references()) {
4469 preserve_cm_referents(per_thread_states);
4470 process_discovered_references(per_thread_states);
4471 } else {
4472 ref_processor_stw()->verify_no_references_recorded();
4473 process_weak_jni_handles();
4474 }
4475
4476 if (G1StringDedup::is_enabled()) {
4477 double fixup_start = os::elapsedTime();
4478
4479 G1STWIsAliveClosure is_alive(this);
4480 G1KeepAliveClosure keep_alive(this);
4481 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4482
4483 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4484 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4485 }
4486
4487 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4488
4489 if (evacuation_failed()) {
4490 restore_after_evac_failure();
4491
4492 // Reset the G1EvacuationFailureALot counters and flags
4493 // Note: the values are reset only when an actual
4494 // evacuation failure occurs.
4495 NOT_PRODUCT(reset_evacuation_should_fail();)
4496 }
4497
4498 _preserved_marks_set.assert_empty();
4499
4500 // Enqueue any remaining references remaining on the STW
4501 // reference processor's discovered lists. We need to do
4502 // this after the card table is cleaned (and verified) as
4503 // the act of enqueueing entries on to the pending list
4504 // will log these updates (and dirty their associated
4505 // cards). We need these updates logged to update any
4506 // RSets.
4507 if (g1_policy()->should_process_references()) {
4508 enqueue_discovered_references(per_thread_states);
4509 } else {
4510 g1_policy()->phase_times()->record_ref_enq_time(0);
4511 }
4512
4513 _allocator->release_gc_alloc_regions(evacuation_info);
4514
4515 merge_per_thread_state_info(per_thread_states);
4516
4517 // Reset and re-enable the hot card cache.
4518 // Note the counts for the cards in the regions in the
4519 // collection set are reset when the collection set is freed.
4520 _hot_card_cache->reset_hot_cache();
4521 _hot_card_cache->set_use_cache(true);
4522
4523 purge_code_root_memory();
4524
4525 redirty_logged_cards();
4526 #if defined(COMPILER2) || INCLUDE_JVMCI
4527 double start = os::elapsedTime();
4528 DerivedPointerTable::update_pointers();
4529 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4530 #endif
4531 g1_policy()->print_age_table();
4532 }
4533
4534 void G1CollectedHeap::record_obj_copy_mem_stats() {
4535 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4536
4537 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4538 create_g1_evac_summary(&_old_evac_stats));
4539 }
4540
4541 void G1CollectedHeap::free_region(HeapRegion* hr,
4542 FreeRegionList* free_list,
4543 bool skip_remset,
4544 bool skip_hot_card_cache,
4545 bool locked) {
4546 assert(!hr->is_free(), "the region should not be free");
4547 assert(!hr->is_empty(), "the region should not be empty");
4548 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4549 assert(free_list != NULL, "pre-condition");
4550
4551 if (G1VerifyBitmaps) {
4552 MemRegion mr(hr->bottom(), hr->end());
4553 concurrent_mark()->clearRangePrevBitmap(mr);
4554 }
4555
4556 // Clear the card counts for this region.
4557 // Note: we only need to do this if the region is not young
4558 // (since we don't refine cards in young regions).
4559 if (!skip_hot_card_cache && !hr->is_young()) {
4560 _hot_card_cache->reset_card_counts(hr);
4561 }
4562 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4563 free_list->add_ordered(hr);
4564 }
4565
4566 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4567 FreeRegionList* free_list,
4568 bool skip_remset) {
4569 assert(hr->is_humongous(), "this is only for humongous regions");
4570 assert(free_list != NULL, "pre-condition");
4571 hr->clear_humongous();
4572 free_region(hr, free_list, skip_remset);
4573 }
4574
4575 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4576 const uint humongous_regions_removed) {
4577 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4578 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4579 _old_set.bulk_remove(old_regions_removed);
4580 _humongous_set.bulk_remove(humongous_regions_removed);
4581 }
4582
4583 }
4584
4585 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4586 assert(list != NULL, "list can't be null");
4587 if (!list->is_empty()) {
4588 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4589 _hrm.insert_list_into_free_list(list);
4590 }
4591 }
4592
4593 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4594 decrease_used(bytes);
4595 }
4596
4597 class G1ParScrubRemSetTask: public AbstractGangTask {
4598 protected:
4599 G1RemSet* _g1rs;
4600 HeapRegionClaimer _hrclaimer;
4601
4602 public:
4603 G1ParScrubRemSetTask(G1RemSet* g1_rs, uint num_workers) :
4604 AbstractGangTask("G1 ScrubRS"),
4605 _g1rs(g1_rs),
4606 _hrclaimer(num_workers) {
4607 }
4608
4609 void work(uint worker_id) {
4610 _g1rs->scrub(worker_id, &_hrclaimer);
4611 }
4612 };
4613
4614 void G1CollectedHeap::scrub_rem_set() {
4615 uint num_workers = workers()->active_workers();
4616 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
4617 workers()->run_task(&g1_par_scrub_rs_task);
4618 }
4619
4620 class G1FreeCollectionSetTask : public AbstractGangTask {
4621 private:
4622
4623 // Closure applied to all regions in the collection set to do work that needs to
4624 // be done serially in a single thread.
4625 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4626 private:
4627 EvacuationInfo* _evacuation_info;
4628 const size_t* _surviving_young_words;
4629
4630 // Bytes used in successfully evacuated regions before the evacuation.
4631 size_t _before_used_bytes;
4632 // Bytes used in unsucessfully evacuated regions before the evacuation
4633 size_t _after_used_bytes;
4634
4635 size_t _bytes_allocated_in_old_since_last_gc;
4636
4637 size_t _failure_used_words;
4638 size_t _failure_waste_words;
4639
4640 FreeRegionList _local_free_list;
4641 public:
4642 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4643 HeapRegionClosure(),
4644 _evacuation_info(evacuation_info),
4645 _surviving_young_words(surviving_young_words),
4646 _before_used_bytes(0),
4647 _after_used_bytes(0),
4648 _bytes_allocated_in_old_since_last_gc(0),
4649 _failure_used_words(0),
4650 _failure_waste_words(0),
4651 _local_free_list("Local Region List for CSet Freeing") {
4652 }
4653
4654 virtual bool doHeapRegion(HeapRegion* r) {
4655 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4656
4657 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4658 g1h->clear_in_cset(r);
4659
4660 if (r->is_young()) {
4661 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4662 "Young index %d is wrong for region %u of type %s with %u young regions",
4663 r->young_index_in_cset(),
4664 r->hrm_index(),
4665 r->get_type_str(),
4666 g1h->collection_set()->young_region_length());
4667 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4668 r->record_surv_words_in_group(words_survived);
4669 }
4670
4671 if (!r->evacuation_failed()) {
4672 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4673 _before_used_bytes += r->used();
4674 g1h->free_region(r,
4675 &_local_free_list,
4676 true, /* skip_remset */
4677 true, /* skip_hot_card_cache */
4678 true /* locked */);
4679 } else {
4680 r->uninstall_surv_rate_group();
4681 r->set_young_index_in_cset(-1);
4682 r->set_evacuation_failed(false);
4683 // When moving a young gen region to old gen, we "allocate" that whole region
4684 // there. This is in addition to any already evacuated objects. Notify the
4685 // policy about that.
4686 // Old gen regions do not cause an additional allocation: both the objects
4687 // still in the region and the ones already moved are accounted for elsewhere.
4688 if (r->is_young()) {
4689 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4690 }
4691 // The region is now considered to be old.
4692 r->set_old();
4693 // Do some allocation statistics accounting. Regions that failed evacuation
4694 // are always made old, so there is no need to update anything in the young
4695 // gen statistics, but we need to update old gen statistics.
4696 size_t used_words = r->marked_bytes() / HeapWordSize;
4697
4698 _failure_used_words += used_words;
4699 _failure_waste_words += HeapRegion::GrainWords - used_words;
4700
4701 g1h->old_set_add(r);
4702 _after_used_bytes += r->used();
4703 }
4704 return false;
4705 }
4706
4707 void complete_work() {
4708 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4709
4710 _evacuation_info->set_regions_freed(_local_free_list.length());
4711 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4712
4713 g1h->prepend_to_freelist(&_local_free_list);
4714 g1h->decrement_summary_bytes(_before_used_bytes);
4715
4716 G1Policy* policy = g1h->g1_policy();
4717 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4718
4719 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4720 }
4721 };
4722
4723 G1CollectionSet* _collection_set;
4724 G1SerialFreeCollectionSetClosure _cl;
4725 const size_t* _surviving_young_words;
4726
4727 size_t _rs_lengths;
4728
4729 volatile jint _serial_work_claim;
4730
4731 struct WorkItem {
4732 uint region_idx;
4733 bool is_young;
4734 bool evacuation_failed;
4735
4736 WorkItem(HeapRegion* r) {
4737 region_idx = r->hrm_index();
4738 is_young = r->is_young();
4739 evacuation_failed = r->evacuation_failed();
4740 }
4741 };
4742
4743 volatile size_t _parallel_work_claim;
4744 size_t _num_work_items;
4745 WorkItem* _work_items;
4746
4747 void do_serial_work() {
4748 // Need to grab the lock to be allowed to modify the old region list.
4749 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4750 _collection_set->iterate(&_cl);
4751 }
4752
4753 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4754 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4755
4756 HeapRegion* r = g1h->region_at(region_idx);
4757 assert(!g1h->is_on_master_free_list(r), "sanity");
4758
4759 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4760
4761 if (!is_young) {
4762 g1h->_hot_card_cache->reset_card_counts(r);
4763 }
4764
4765 if (!evacuation_failed) {
4766 r->rem_set()->clear_locked();
4767 }
4768 }
4769
4770 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4771 private:
4772 size_t _cur_idx;
4773 WorkItem* _work_items;
4774 public:
4775 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4776
4777 virtual bool doHeapRegion(HeapRegion* r) {
4778 _work_items[_cur_idx++] = WorkItem(r);
4779 return false;
4780 }
4781 };
4782
4783 void prepare_work() {
4784 G1PrepareFreeCollectionSetClosure cl(_work_items);
4785 _collection_set->iterate(&cl);
4786 }
4787
4788 void complete_work() {
4789 _cl.complete_work();
4790
4791 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4792 policy->record_max_rs_lengths(_rs_lengths);
4793 policy->cset_regions_freed();
4794 }
4795 public:
4796 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4797 AbstractGangTask("G1 Free Collection Set"),
4798 _cl(evacuation_info, surviving_young_words),
4799 _collection_set(collection_set),
4800 _surviving_young_words(surviving_young_words),
4801 _serial_work_claim(0),
4802 _rs_lengths(0),
4803 _parallel_work_claim(0),
4804 _num_work_items(collection_set->region_length()),
4805 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4806 prepare_work();
4807 }
4808
4809 ~G1FreeCollectionSetTask() {
4810 complete_work();
4811 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4812 }
4813
4814 // Chunk size for work distribution. The chosen value has been determined experimentally
4815 // to be a good tradeoff between overhead and achievable parallelism.
4816 static uint chunk_size() { return 32; }
4817
4818 virtual void work(uint worker_id) {
4819 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4820
4821 // Claim serial work.
4822 if (_serial_work_claim == 0) {
4823 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4824 if (value == 0) {
4825 double serial_time = os::elapsedTime();
4826 do_serial_work();
4827 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4828 }
4829 }
4830
4831 // Start parallel work.
4832 double young_time = 0.0;
4833 bool has_young_time = false;
4834 double non_young_time = 0.0;
4835 bool has_non_young_time = false;
4836
4837 while (true) {
4838 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4839 size_t cur = end - chunk_size();
4840
4841 if (cur >= _num_work_items) {
4842 break;
4843 }
4844
4845 double start_time = os::elapsedTime();
4846
4847 end = MIN2(end, _num_work_items);
4848
4849 for (; cur < end; cur++) {
4850 bool is_young = _work_items[cur].is_young;
4851
4852 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4853
4854 double end_time = os::elapsedTime();
4855 double time_taken = end_time - start_time;
4856 if (is_young) {
4857 young_time += time_taken;
4858 has_young_time = true;
4859 } else {
4860 non_young_time += time_taken;
4861 has_non_young_time = true;
4862 }
4863 start_time = end_time;
4864 }
4865 }
4866
4867 if (has_young_time) {
4868 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4869 }
4870 if (has_non_young_time) {
4871 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
4872 }
4873 }
4874 };
4875
4876 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4877 _eden.clear();
4878
4879 double free_cset_start_time = os::elapsedTime();
4880
4881 {
4882 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4883 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4884
4885 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4886
4887 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4888 cl.name(),
4889 num_workers,
4890 _collection_set.region_length());
4891 workers()->run_task(&cl, num_workers);
4892 }
4893 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4894
4895 collection_set->clear();
4896 }
4897
4898 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4899 private:
4900 FreeRegionList* _free_region_list;
4901 HeapRegionSet* _proxy_set;
4902 uint _humongous_objects_reclaimed;
4903 uint _humongous_regions_reclaimed;
4904 size_t _freed_bytes;
4905 public:
4906
4907 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4908 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4909 }
4910
4911 virtual bool doHeapRegion(HeapRegion* r) {
4912 if (!r->is_starts_humongous()) {
4913 return false;
4914 }
4915
4916 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4917
4918 oop obj = (oop)r->bottom();
4919 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4920
4921 // The following checks whether the humongous object is live are sufficient.
4922 // The main additional check (in addition to having a reference from the roots
4923 // or the young gen) is whether the humongous object has a remembered set entry.
4924 //
4925 // A humongous object cannot be live if there is no remembered set for it
4926 // because:
4927 // - there can be no references from within humongous starts regions referencing
4928 // the object because we never allocate other objects into them.
4929 // (I.e. there are no intra-region references that may be missed by the
4930 // remembered set)
4931 // - as soon there is a remembered set entry to the humongous starts region
4932 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4933 // until the end of a concurrent mark.
4934 //
4935 // It is not required to check whether the object has been found dead by marking
4936 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4937 // all objects allocated during that time are considered live.
4938 // SATB marking is even more conservative than the remembered set.
4939 // So if at this point in the collection there is no remembered set entry,
4940 // nobody has a reference to it.
4941 // At the start of collection we flush all refinement logs, and remembered sets
4942 // are completely up-to-date wrt to references to the humongous object.
4943 //
4944 // Other implementation considerations:
4945 // - never consider object arrays at this time because they would pose
4946 // considerable effort for cleaning up the the remembered sets. This is
4947 // required because stale remembered sets might reference locations that
4948 // are currently allocated into.
4949 uint region_idx = r->hrm_index();
4950 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4951 !r->rem_set()->is_empty()) {
4952 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",
4953 region_idx,
4954 (size_t)obj->size() * HeapWordSize,
4955 p2i(r->bottom()),
4956 r->rem_set()->occupied(),
4957 r->rem_set()->strong_code_roots_list_length(),
4958 next_bitmap->isMarked(r->bottom()),
4959 g1h->is_humongous_reclaim_candidate(region_idx),
4960 obj->is_typeArray()
4961 );
4962 return false;
4963 }
4964
4965 guarantee(obj->is_typeArray(),
4966 "Only eagerly reclaiming type arrays is supported, but the object "
4967 PTR_FORMAT " is not.", p2i(r->bottom()));
4968
4969 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",
4970 region_idx,
4971 (size_t)obj->size() * HeapWordSize,
4972 p2i(r->bottom()),
4973 r->rem_set()->occupied(),
4974 r->rem_set()->strong_code_roots_list_length(),
4975 next_bitmap->isMarked(r->bottom()),
4976 g1h->is_humongous_reclaim_candidate(region_idx),
4977 obj->is_typeArray()
4978 );
4979
4980 // Need to clear mark bit of the humongous object if already set.
4981 if (next_bitmap->isMarked(r->bottom())) {
4982 next_bitmap->clear(r->bottom());
4983 }
4984 _humongous_objects_reclaimed++;
4985 do {
4986 HeapRegion* next = g1h->next_region_in_humongous(r);
4987 _freed_bytes += r->used();
4988 r->set_containing_set(NULL);
4989 _humongous_regions_reclaimed++;
4990 g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
4991 r = next;
4992 } while (r != NULL);
4993
4994 return false;
4995 }
4996
4997 uint humongous_objects_reclaimed() {
4998 return _humongous_objects_reclaimed;
4999 }
5000
5001 uint humongous_regions_reclaimed() {
5002 return _humongous_regions_reclaimed;
5003 }
5004
5005 size_t bytes_freed() const {
5006 return _freed_bytes;
5007 }
5008 };
5009
5010 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5011 assert_at_safepoint(true);
5012
5013 if (!G1EagerReclaimHumongousObjects ||
5014 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5015 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5016 return;
5017 }
5018
5019 double start_time = os::elapsedTime();
5020
5021 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5022
5023 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5024 heap_region_iterate(&cl);
5025
5026 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
5027
5028 G1HRPrinter* hrp = hr_printer();
5029 if (hrp->is_active()) {
5030 FreeRegionListIterator iter(&local_cleanup_list);
5031 while (iter.more_available()) {
5032 HeapRegion* hr = iter.get_next();
5033 hrp->cleanup(hr);
5034 }
5035 }
5036
5037 prepend_to_freelist(&local_cleanup_list);
5038 decrement_summary_bytes(cl.bytes_freed());
5039
5040 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5041 cl.humongous_objects_reclaimed());
5042 }
5043
5044 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
5045 public:
5046 virtual bool doHeapRegion(HeapRegion* r) {
5047 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
5048 G1CollectedHeap::heap()->clear_in_cset(r);
5049 r->set_young_index_in_cset(-1);
5050 return false;
5051 }
5052 };
5053
5054 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
5055 G1AbandonCollectionSetClosure cl;
5056 collection_set->iterate(&cl);
5057
5058 collection_set->clear();
5059 collection_set->stop_incremental_building();
5060 }
5061
5062 void G1CollectedHeap::set_free_regions_coming() {
5063 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5064
5065 assert(!free_regions_coming(), "pre-condition");
5066 _free_regions_coming = true;
5067 }
5068
5069 void G1CollectedHeap::reset_free_regions_coming() {
5070 assert(free_regions_coming(), "pre-condition");
5071
5072 {
5073 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5074 _free_regions_coming = false;
5075 SecondaryFreeList_lock->notify_all();
5076 }
5077
5078 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5079 }
5080
5081 void G1CollectedHeap::wait_while_free_regions_coming() {
5082 // Most of the time we won't have to wait, so let's do a quick test
5083 // first before we take the lock.
5084 if (!free_regions_coming()) {
5085 return;
5086 }
5087
5088 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5089
5090 {
5091 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5092 while (free_regions_coming()) {
5093 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5094 }
5095 }
5096
5097 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5098 }
5099
5100 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5101 return _allocator->is_retained_old_region(hr);
5102 }
5103
5104 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5105 _eden.add(hr);
5106 _g1_policy->set_region_eden(hr);
5107 }
5108
5109 #ifdef ASSERT
5110
5111 class NoYoungRegionsClosure: public HeapRegionClosure {
5112 private:
5113 bool _success;
5114 public:
5115 NoYoungRegionsClosure() : _success(true) { }
5116 bool doHeapRegion(HeapRegion* r) {
5117 if (r->is_young()) {
5118 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5119 p2i(r->bottom()), p2i(r->end()));
5120 _success = false;
5121 }
5122 return false;
5123 }
5124 bool success() { return _success; }
5125 };
5126
5127 bool G1CollectedHeap::check_young_list_empty() {
5128 bool ret = (young_regions_count() == 0);
5129
5130 NoYoungRegionsClosure closure;
5131 heap_region_iterate(&closure);
5132 ret = ret && closure.success();
5133
5134 return ret;
5135 }
5136
5137 #endif // ASSERT
5138
5139 class TearDownRegionSetsClosure : public HeapRegionClosure {
5140 private:
5141 HeapRegionSet *_old_set;
5142
5143 public:
5144 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5145
5146 bool doHeapRegion(HeapRegion* r) {
5147 if (r->is_old()) {
5148 _old_set->remove(r);
5149 } else if(r->is_young()) {
5150 r->uninstall_surv_rate_group();
5151 } else {
5152 // We ignore free regions, we'll empty the free list afterwards.
5153 // We ignore humongous regions, we're not tearing down the
5154 // humongous regions set.
5155 assert(r->is_free() || r->is_humongous(),
5156 "it cannot be another type");
5157 }
5158 return false;
5159 }
5160
5161 ~TearDownRegionSetsClosure() {
5162 assert(_old_set->is_empty(), "post-condition");
5163 }
5164 };
5165
5166 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5167 assert_at_safepoint(true /* should_be_vm_thread */);
5168
5169 if (!free_list_only) {
5170 TearDownRegionSetsClosure cl(&_old_set);
5171 heap_region_iterate(&cl);
5172
5173 // Note that emptying the _young_list is postponed and instead done as
5174 // the first step when rebuilding the regions sets again. The reason for
5175 // this is that during a full GC string deduplication needs to know if
5176 // a collected region was young or old when the full GC was initiated.
5177 }
5178 _hrm.remove_all_free_regions();
5179 }
5180
5181 void G1CollectedHeap::increase_used(size_t bytes) {
5182 _summary_bytes_used += bytes;
5183 }
5184
5185 void G1CollectedHeap::decrease_used(size_t bytes) {
5186 assert(_summary_bytes_used >= bytes,
5187 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5188 _summary_bytes_used, bytes);
5189 _summary_bytes_used -= bytes;
5190 }
5191
5192 void G1CollectedHeap::set_used(size_t bytes) {
5193 _summary_bytes_used = bytes;
5194 }
5195
5196 class RebuildRegionSetsClosure : public HeapRegionClosure {
5197 private:
5198 bool _free_list_only;
5199 HeapRegionSet* _old_set;
5200 HeapRegionManager* _hrm;
5201 size_t _total_used;
5202
5203 public:
5204 RebuildRegionSetsClosure(bool free_list_only,
5205 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5206 _free_list_only(free_list_only),
5207 _old_set(old_set), _hrm(hrm), _total_used(0) {
5208 assert(_hrm->num_free_regions() == 0, "pre-condition");
5209 if (!free_list_only) {
5210 assert(_old_set->is_empty(), "pre-condition");
5211 }
5212 }
5213
5214 bool doHeapRegion(HeapRegion* r) {
5215 if (r->is_empty()) {
5216 // Add free regions to the free list
5217 r->set_free();
5218 r->set_allocation_context(AllocationContext::system());
5219 _hrm->insert_into_free_list(r);
5220 } else if (!_free_list_only) {
5221
5222 if (r->is_humongous()) {
5223 // We ignore humongous regions. We left the humongous set unchanged.
5224 } else {
5225 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
5226 // We now consider all regions old, so register as such. Leave
5227 // archive regions set that way, however, while still adding
5228 // them to the old set.
5229 if (!r->is_archive()) {
5230 r->set_old();
5231 }
5232 _old_set->add(r);
5233 }
5234 _total_used += r->used();
5235 }
5236
5237 return false;
5238 }
5239
5240 size_t total_used() {
5241 return _total_used;
5242 }
5243 };
5244
5245 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5246 assert_at_safepoint(true /* should_be_vm_thread */);
5247
5248 if (!free_list_only) {
5249 _eden.clear();
5250 _survivor.clear();
5251 }
5252
5253 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5254 heap_region_iterate(&cl);
5255
5256 if (!free_list_only) {
5257 set_used(cl.total_used());
5258 if (_archive_allocator != NULL) {
5259 _archive_allocator->clear_used();
5260 }
5261 }
5262 assert(used_unlocked() == recalculate_used(),
5263 "inconsistent used_unlocked(), "
5264 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5265 used_unlocked(), recalculate_used());
5266 }
5267
5268 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5269 HeapRegion* hr = heap_region_containing(p);
5270 return hr->is_in(p);
5271 }
5272
5273 // Methods for the mutator alloc region
5274
5275 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5276 bool force) {
5277 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5278 bool should_allocate = g1_policy()->should_allocate_mutator_region();
5279 if (force || should_allocate) {
5280 HeapRegion* new_alloc_region = new_region(word_size,
5281 false /* is_old */,
5282 false /* do_expand */);
5283 if (new_alloc_region != NULL) {
5284 set_region_short_lived_locked(new_alloc_region);
5285 _hr_printer.alloc(new_alloc_region, !should_allocate);
5286 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5287 return new_alloc_region;
5288 }
5289 }
5290 return NULL;
5291 }
5292
5293 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5294 size_t allocated_bytes) {
5295 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5296 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5297
5298 collection_set()->add_eden_region(alloc_region);
5299 increase_used(allocated_bytes);
5300 _hr_printer.retire(alloc_region);
5301 // We update the eden sizes here, when the region is retired,
5302 // instead of when it's allocated, since this is the point that its
5303 // used space has been recored in _summary_bytes_used.
5304 g1mm()->update_eden_size();
5305 }
5306
5307 // Methods for the GC alloc regions
5308
5309 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
5310 if (dest.is_old()) {
5311 return true;
5312 } else {
5313 return survivor_regions_count() < g1_policy()->max_survivor_regions();
5314 }
5315 }
5316
5317 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
5318 assert(FreeList_lock->owned_by_self(), "pre-condition");
5319
5320 if (!has_more_regions(dest)) {
5321 return NULL;
5322 }
5323
5324 const bool is_survivor = dest.is_young();
5325
5326 HeapRegion* new_alloc_region = new_region(word_size,
5327 !is_survivor,
5328 true /* do_expand */);
5329 if (new_alloc_region != NULL) {
5330 // We really only need to do this for old regions given that we
5331 // should never scan survivors. But it doesn't hurt to do it
5332 // for survivors too.
5333 new_alloc_region->record_timestamp();
5334 if (is_survivor) {
5335 new_alloc_region->set_survivor();
5336 _survivor.add(new_alloc_region);
5337 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5338 } else {
5339 new_alloc_region->set_old();
5340 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5341 }
5342 _hr_printer.alloc(new_alloc_region);
5343 bool during_im = collector_state()->during_initial_mark_pause();
5344 new_alloc_region->note_start_of_copying(during_im);
5345 return new_alloc_region;
5346 }
5347 return NULL;
5348 }
5349
5350 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5351 size_t allocated_bytes,
5352 InCSetState dest) {
5353 bool during_im = collector_state()->during_initial_mark_pause();
5354 alloc_region->note_end_of_copying(during_im);
5355 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5356 if (dest.is_old()) {
5357 _old_set.add(alloc_region);
5358 }
5359 _hr_printer.retire(alloc_region);
5360 }
5361
5362 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5363 bool expanded = false;
5364 uint index = _hrm.find_highest_free(&expanded);
5365
5366 if (index != G1_NO_HRM_INDEX) {
5367 if (expanded) {
5368 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5369 HeapRegion::GrainWords * HeapWordSize);
5370 }
5371 _hrm.allocate_free_regions_starting_at(index, 1);
5372 return region_at(index);
5373 }
5374 return NULL;
5375 }
5376
5377 // Optimized nmethod scanning
5378
5379 class RegisterNMethodOopClosure: public OopClosure {
5380 G1CollectedHeap* _g1h;
5381 nmethod* _nm;
5382
5383 template <class T> void do_oop_work(T* p) {
5384 T heap_oop = oopDesc::load_heap_oop(p);
5385 if (!oopDesc::is_null(heap_oop)) {
5386 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5387 HeapRegion* hr = _g1h->heap_region_containing(obj);
5388 assert(!hr->is_continues_humongous(),
5389 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5390 " starting at " HR_FORMAT,
5391 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5392
5393 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5394 hr->add_strong_code_root_locked(_nm);
5395 }
5396 }
5397
5398 public:
5399 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5400 _g1h(g1h), _nm(nm) {}
5401
5402 void do_oop(oop* p) { do_oop_work(p); }
5403 void do_oop(narrowOop* p) { do_oop_work(p); }
5404 };
5405
5406 class UnregisterNMethodOopClosure: public OopClosure {
5407 G1CollectedHeap* _g1h;
5408 nmethod* _nm;
5409
5410 template <class T> void do_oop_work(T* p) {
5411 T heap_oop = oopDesc::load_heap_oop(p);
5412 if (!oopDesc::is_null(heap_oop)) {
5413 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5414 HeapRegion* hr = _g1h->heap_region_containing(obj);
5415 assert(!hr->is_continues_humongous(),
5416 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5417 " starting at " HR_FORMAT,
5418 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5419
5420 hr->remove_strong_code_root(_nm);
5421 }
5422 }
5423
5424 public:
5425 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5426 _g1h(g1h), _nm(nm) {}
5427
5428 void do_oop(oop* p) { do_oop_work(p); }
5429 void do_oop(narrowOop* p) { do_oop_work(p); }
5430 };
5431
5432 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5433 CollectedHeap::register_nmethod(nm);
5434
5435 guarantee(nm != NULL, "sanity");
5436 RegisterNMethodOopClosure reg_cl(this, nm);
5437 nm->oops_do(®_cl);
5438 }
5439
5440 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5441 CollectedHeap::unregister_nmethod(nm);
5442
5443 guarantee(nm != NULL, "sanity");
5444 UnregisterNMethodOopClosure reg_cl(this, nm);
5445 nm->oops_do(®_cl, true);
5446 }
5447
5448 void G1CollectedHeap::purge_code_root_memory() {
5449 double purge_start = os::elapsedTime();
5450 G1CodeRootSet::purge();
5451 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5452 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5453 }
5454
5455 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5456 G1CollectedHeap* _g1h;
5457
5458 public:
5459 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5460 _g1h(g1h) {}
5461
5462 void do_code_blob(CodeBlob* cb) {
5463 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5464 if (nm == NULL) {
5465 return;
5466 }
5467
5468 if (ScavengeRootsInCode) {
5469 _g1h->register_nmethod(nm);
5470 }
5471 }
5472 };
5473
5474 void G1CollectedHeap::rebuild_strong_code_roots() {
5475 RebuildStrongCodeRootClosure blob_cl(this);
5476 CodeCache::blobs_do(&blob_cl);
5477 }