1 /*
2 * Copyright (c) 2001, 2015, 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/symbolTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc/g1/concurrentMark.inline.hpp"
30 #include "gc/g1/concurrentMarkThread.inline.hpp"
31 #include "gc/g1/g1CollectedHeap.inline.hpp"
32 #include "gc/g1/g1CollectorPolicy.hpp"
33 #include "gc/g1/g1CollectorState.hpp"
34 #include "gc/g1/g1OopClosures.inline.hpp"
35 #include "gc/g1/g1RemSet.hpp"
36 #include "gc/g1/g1StringDedup.hpp"
37 #include "gc/g1/heapRegion.inline.hpp"
38 #include "gc/g1/heapRegionManager.inline.hpp"
39 #include "gc/g1/heapRegionRemSet.hpp"
40 #include "gc/g1/heapRegionSet.inline.hpp"
41 #include "gc/g1/suspendibleThreadSet.hpp"
42 #include "gc/shared/gcId.hpp"
43 #include "gc/shared/gcTimer.hpp"
44 #include "gc/shared/gcTrace.hpp"
45 #include "gc/shared/gcTraceTime.inline.hpp"
46 #include "gc/shared/genOopClosures.inline.hpp"
47 #include "gc/shared/referencePolicy.hpp"
48 #include "gc/shared/strongRootsScope.hpp"
49 #include "gc/shared/taskqueue.inline.hpp"
50 #include "gc/shared/vmGCOperations.hpp"
51 #include "logging/log.hpp"
52 #include "memory/allocation.hpp"
53 #include "memory/resourceArea.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "runtime/atomic.inline.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/prefetch.inline.hpp"
59 #include "services/memTracker.hpp"
60
61 // Concurrent marking bit map wrapper
62
63 CMBitMapRO::CMBitMapRO(int shifter) :
64 _bm(),
65 _shifter(shifter) {
66 _bmStartWord = 0;
67 _bmWordSize = 0;
68 }
69
70 HeapWord* CMBitMapRO::getNextMarkedWordAddress(const HeapWord* addr,
71 const HeapWord* limit) const {
72 // First we must round addr *up* to a possible object boundary.
73 addr = (HeapWord*)align_size_up((intptr_t)addr,
74 HeapWordSize << _shifter);
75 size_t addrOffset = heapWordToOffset(addr);
76 assert(limit != NULL, "limit must not be NULL");
77 size_t limitOffset = heapWordToOffset(limit);
78 size_t nextOffset = _bm.get_next_one_offset(addrOffset, limitOffset);
79 HeapWord* nextAddr = offsetToHeapWord(nextOffset);
80 assert(nextAddr >= addr, "get_next_one postcondition");
81 assert(nextAddr == limit || isMarked(nextAddr),
82 "get_next_one postcondition");
83 return nextAddr;
84 }
85
86 #ifndef PRODUCT
87 bool CMBitMapRO::covers(MemRegion heap_rs) const {
88 // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
89 assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
90 "size inconsistency");
91 return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
92 _bmWordSize == heap_rs.word_size();
93 }
94 #endif
95
96 void CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
97 _bm.print_on_error(st, prefix);
98 }
99
100 size_t CMBitMap::compute_size(size_t heap_size) {
101 return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
102 }
103
104 size_t CMBitMap::mark_distance() {
105 return MinObjAlignmentInBytes * BitsPerByte;
106 }
107
108 void CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
109 _bmStartWord = heap.start();
110 _bmWordSize = heap.word_size();
111
112 _bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
113 _bm.set_size(_bmWordSize >> _shifter);
114
115 storage->set_mapping_changed_listener(&_listener);
116 }
117
118 void CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions, bool zero_filled) {
119 if (zero_filled) {
120 return;
121 }
122 // We need to clear the bitmap on commit, removing any existing information.
123 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
124 _bm->clearRange(mr);
125 }
126
127 // Closure used for clearing the given mark bitmap.
128 class ClearBitmapHRClosure : public HeapRegionClosure {
129 private:
130 ConcurrentMark* _cm;
131 CMBitMap* _bitmap;
132 bool _may_yield; // The closure may yield during iteration. If yielded, abort the iteration.
133 public:
134 ClearBitmapHRClosure(ConcurrentMark* cm, CMBitMap* bitmap, bool may_yield) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) {
135 assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield.");
136 }
137
138 virtual bool doHeapRegion(HeapRegion* r) {
139 size_t const chunk_size_in_words = M / HeapWordSize;
140
141 HeapWord* cur = r->bottom();
142 HeapWord* const end = r->end();
143
144 while (cur < end) {
145 MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
146 _bitmap->clearRange(mr);
147
148 cur += chunk_size_in_words;
149
150 // Abort iteration if after yielding the marking has been aborted.
151 if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) {
152 return true;
153 }
154 // Repeat the asserts from before the start of the closure. We will do them
155 // as asserts here to minimize their overhead on the product. However, we
156 // will have them as guarantees at the beginning / end of the bitmap
157 // clearing to get some checking in the product.
158 assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant");
159 assert(!_may_yield || !G1CollectedHeap::heap()->collector_state()->mark_in_progress(), "invariant");
160 }
161
162 return false;
163 }
164 };
165
166 class ParClearNextMarkBitmapTask : public AbstractGangTask {
167 ClearBitmapHRClosure* _cl;
168 HeapRegionClaimer _hrclaimer;
169 bool _suspendible; // If the task is suspendible, workers must join the STS.
170
171 public:
172 ParClearNextMarkBitmapTask(ClearBitmapHRClosure *cl, uint n_workers, bool suspendible) :
173 _cl(cl), _suspendible(suspendible), AbstractGangTask("Parallel Clear Bitmap Task"), _hrclaimer(n_workers) {}
174
175 void work(uint worker_id) {
176 SuspendibleThreadSetJoiner sts_join(_suspendible);
177 G1CollectedHeap::heap()->heap_region_par_iterate(_cl, worker_id, &_hrclaimer, true);
178 }
179 };
180
181 void CMBitMap::clearAll() {
182 G1CollectedHeap* g1h = G1CollectedHeap::heap();
183 ClearBitmapHRClosure cl(NULL, this, false /* may_yield */);
184 uint n_workers = g1h->workers()->active_workers();
185 ParClearNextMarkBitmapTask task(&cl, n_workers, false);
186 g1h->workers()->run_task(&task);
187 guarantee(cl.complete(), "Must have completed iteration.");
188 return;
189 }
190
191 void CMBitMap::clearRange(MemRegion mr) {
192 mr.intersection(MemRegion(_bmStartWord, _bmWordSize));
193 assert(!mr.is_empty(), "unexpected empty region");
194 // convert address range into offset range
195 _bm.at_put_range(heapWordToOffset(mr.start()),
196 heapWordToOffset(mr.end()), false);
197 }
198
199 CMMarkStack::CMMarkStack(ConcurrentMark* cm) :
200 _base(NULL), _cm(cm)
201 {}
202
203 bool CMMarkStack::allocate(size_t capacity) {
204 // allocate a stack of the requisite depth
205 ReservedSpace rs(ReservedSpace::allocation_align_size_up(capacity * sizeof(oop)));
206 if (!rs.is_reserved()) {
207 warning("ConcurrentMark MarkStack allocation failure");
208 return false;
209 }
210 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
211 if (!_virtual_space.initialize(rs, rs.size())) {
212 warning("ConcurrentMark MarkStack backing store failure");
213 // Release the virtual memory reserved for the marking stack
214 rs.release();
215 return false;
216 }
217 assert(_virtual_space.committed_size() == rs.size(),
218 "Didn't reserve backing store for all of ConcurrentMark stack?");
219 _base = (oop*) _virtual_space.low();
220 setEmpty();
221 _capacity = (jint) capacity;
222 _saved_index = -1;
223 _should_expand = false;
224 return true;
225 }
226
227 void CMMarkStack::expand() {
228 // Called, during remark, if we've overflown the marking stack during marking.
229 assert(isEmpty(), "stack should been emptied while handling overflow");
230 assert(_capacity <= (jint) MarkStackSizeMax, "stack bigger than permitted");
231 // Clear expansion flag
232 _should_expand = false;
233 if (_capacity == (jint) MarkStackSizeMax) {
234 log_trace(gc)("(benign) Can't expand marking stack capacity, at max size limit");
235 return;
236 }
237 // Double capacity if possible
238 jint new_capacity = MIN2(_capacity*2, (jint) MarkStackSizeMax);
239 // Do not give up existing stack until we have managed to
240 // get the double capacity that we desired.
241 ReservedSpace rs(ReservedSpace::allocation_align_size_up(new_capacity *
242 sizeof(oop)));
243 if (rs.is_reserved()) {
244 // Release the backing store associated with old stack
245 _virtual_space.release();
246 // Reinitialize virtual space for new stack
247 if (!_virtual_space.initialize(rs, rs.size())) {
248 fatal("Not enough swap for expanded marking stack capacity");
249 }
250 _base = (oop*)(_virtual_space.low());
251 _index = 0;
252 _capacity = new_capacity;
253 } else {
254 // Failed to double capacity, continue;
255 log_trace(gc)("(benign) Failed to expand marking stack capacity from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
256 _capacity / K, new_capacity / K);
257 }
258 }
259
260 void CMMarkStack::set_should_expand() {
261 // If we're resetting the marking state because of an
262 // marking stack overflow, record that we should, if
263 // possible, expand the stack.
264 _should_expand = _cm->has_overflown();
265 }
266
267 CMMarkStack::~CMMarkStack() {
268 if (_base != NULL) {
269 _base = NULL;
270 _virtual_space.release();
271 }
272 }
273
274 void CMMarkStack::par_push_arr(oop* ptr_arr, int n) {
275 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
276 jint start = _index;
277 jint next_index = start + n;
278 if (next_index > _capacity) {
279 _overflow = true;
280 return;
281 }
282 // Otherwise.
283 _index = next_index;
284 for (int i = 0; i < n; i++) {
285 int ind = start + i;
286 assert(ind < _capacity, "By overflow test above.");
287 _base[ind] = ptr_arr[i];
288 }
289 }
290
291 bool CMMarkStack::par_pop_arr(oop* ptr_arr, int max, int* n) {
292 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
293 jint index = _index;
294 if (index == 0) {
295 *n = 0;
296 return false;
297 } else {
298 int k = MIN2(max, index);
299 jint new_ind = index - k;
300 for (int j = 0; j < k; j++) {
301 ptr_arr[j] = _base[new_ind + j];
302 }
303 _index = new_ind;
304 *n = k;
305 return true;
306 }
307 }
308
309 void CMMarkStack::note_start_of_gc() {
310 assert(_saved_index == -1,
311 "note_start_of_gc()/end_of_gc() bracketed incorrectly");
312 _saved_index = _index;
313 }
314
315 void CMMarkStack::note_end_of_gc() {
316 // This is intentionally a guarantee, instead of an assert. If we
317 // accidentally add something to the mark stack during GC, it
318 // will be a correctness issue so it's better if we crash. we'll
319 // only check this once per GC anyway, so it won't be a performance
320 // issue in any way.
321 guarantee(_saved_index == _index,
322 "saved index: %d index: %d", _saved_index, _index);
323 _saved_index = -1;
324 }
325
326 CMRootRegions::CMRootRegions() :
327 _young_list(NULL), _cm(NULL), _scan_in_progress(false),
328 _should_abort(false), _next_survivor(NULL) { }
329
330 void CMRootRegions::init(G1CollectedHeap* g1h, ConcurrentMark* cm) {
331 _young_list = g1h->young_list();
332 _cm = cm;
333 }
334
335 void CMRootRegions::prepare_for_scan() {
336 assert(!scan_in_progress(), "pre-condition");
337
338 // Currently, only survivors can be root regions.
339 assert(_next_survivor == NULL, "pre-condition");
340 _next_survivor = _young_list->first_survivor_region();
341 _scan_in_progress = (_next_survivor != NULL);
342 _should_abort = false;
343 }
344
345 HeapRegion* CMRootRegions::claim_next() {
346 if (_should_abort) {
347 // If someone has set the should_abort flag, we return NULL to
348 // force the caller to bail out of their loop.
349 return NULL;
350 }
351
352 // Currently, only survivors can be root regions.
353 HeapRegion* res = _next_survivor;
354 if (res != NULL) {
355 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
356 // Read it again in case it changed while we were waiting for the lock.
357 res = _next_survivor;
358 if (res != NULL) {
359 if (res == _young_list->last_survivor_region()) {
360 // We just claimed the last survivor so store NULL to indicate
361 // that we're done.
362 _next_survivor = NULL;
363 } else {
364 _next_survivor = res->get_next_young_region();
365 }
366 } else {
367 // Someone else claimed the last survivor while we were trying
368 // to take the lock so nothing else to do.
369 }
370 }
371 assert(res == NULL || res->is_survivor(), "post-condition");
372
373 return res;
374 }
375
376 void CMRootRegions::scan_finished() {
377 assert(scan_in_progress(), "pre-condition");
378
379 // Currently, only survivors can be root regions.
380 if (!_should_abort) {
381 assert(_next_survivor == NULL, "we should have claimed all survivors");
382 }
383 _next_survivor = NULL;
384
385 {
386 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
387 _scan_in_progress = false;
388 RootRegionScan_lock->notify_all();
389 }
390 }
391
392 bool CMRootRegions::wait_until_scan_finished() {
393 if (!scan_in_progress()) return false;
394
395 {
396 MutexLockerEx x(RootRegionScan_lock, Mutex::_no_safepoint_check_flag);
397 while (scan_in_progress()) {
398 RootRegionScan_lock->wait(Mutex::_no_safepoint_check_flag);
399 }
400 }
401 return true;
402 }
403
404 uint ConcurrentMark::scale_parallel_threads(uint n_par_threads) {
405 return MAX2((n_par_threads + 2) / 4, 1U);
406 }
407
408 ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
409 _g1h(g1h),
410 _markBitMap1(),
411 _markBitMap2(),
412 _parallel_marking_threads(0),
413 _max_parallel_marking_threads(0),
414 _sleep_factor(0.0),
415 _marking_task_overhead(1.0),
416 _cleanup_list("Cleanup List"),
417 _region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/),
418 _card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >>
419 CardTableModRefBS::card_shift,
420 false /* in_resource_area*/),
421
422 _prevMarkBitMap(&_markBitMap1),
423 _nextMarkBitMap(&_markBitMap2),
424
425 _markStack(this),
426 // _finger set in set_non_marking_state
427
428 _max_worker_id(ParallelGCThreads),
429 // _active_tasks set in set_non_marking_state
430 // _tasks set inside the constructor
431 _task_queues(new CMTaskQueueSet((int) _max_worker_id)),
432 _terminator(ParallelTaskTerminator((int) _max_worker_id, _task_queues)),
433
434 _has_overflown(false),
435 _concurrent(false),
436 _has_aborted(false),
437 _restart_for_overflow(false),
438 _concurrent_marking_in_progress(false),
439 _concurrent_phase_started(false),
440
441 // _verbose_level set below
442
443 _init_times(),
444 _remark_times(), _remark_mark_times(), _remark_weak_ref_times(),
445 _cleanup_times(),
446 _total_counting_time(0.0),
447 _total_rs_scrub_time(0.0),
448
449 _parallel_workers(NULL),
450
451 _count_card_bitmaps(NULL),
452 _count_marked_bytes(NULL),
453 _completed_initialization(false) {
454
455 _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
456 _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
457
458 // Create & start a ConcurrentMark thread.
459 _cmThread = new ConcurrentMarkThread(this);
460 assert(cmThread() != NULL, "CM Thread should have been created");
461 assert(cmThread()->cm() != NULL, "CM Thread should refer to this cm");
462 if (_cmThread->osthread() == NULL) {
463 vm_shutdown_during_initialization("Could not create ConcurrentMarkThread");
464 }
465
466 assert(CGC_lock != NULL, "Where's the CGC_lock?");
467 assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
468 assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
469
470 SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
471 satb_qs.set_buffer_size(G1SATBBufferSize);
472
473 _root_regions.init(_g1h, this);
474
475 if (ConcGCThreads > ParallelGCThreads) {
476 warning("Can't have more ConcGCThreads (%u) "
477 "than ParallelGCThreads (%u).",
478 ConcGCThreads, ParallelGCThreads);
479 return;
480 }
481 if (!FLAG_IS_DEFAULT(ConcGCThreads) && ConcGCThreads > 0) {
482 // Note: ConcGCThreads has precedence over G1MarkingOverheadPercent
483 // if both are set
484 _sleep_factor = 0.0;
485 _marking_task_overhead = 1.0;
486 } else if (G1MarkingOverheadPercent > 0) {
487 // We will calculate the number of parallel marking threads based
488 // on a target overhead with respect to the soft real-time goal
489 double marking_overhead = (double) G1MarkingOverheadPercent / 100.0;
490 double overall_cm_overhead =
491 (double) MaxGCPauseMillis * marking_overhead /
492 (double) GCPauseIntervalMillis;
493 double cpu_ratio = 1.0 / (double) os::processor_count();
494 double marking_thread_num = ceil(overall_cm_overhead / cpu_ratio);
495 double marking_task_overhead =
496 overall_cm_overhead / marking_thread_num *
497 (double) os::processor_count();
498 double sleep_factor =
499 (1.0 - marking_task_overhead) / marking_task_overhead;
500
501 FLAG_SET_ERGO(uint, ConcGCThreads, (uint) marking_thread_num);
502 _sleep_factor = sleep_factor;
503 _marking_task_overhead = marking_task_overhead;
504 } else {
505 // Calculate the number of parallel marking threads by scaling
506 // the number of parallel GC threads.
507 uint marking_thread_num = scale_parallel_threads(ParallelGCThreads);
508 FLAG_SET_ERGO(uint, ConcGCThreads, marking_thread_num);
509 _sleep_factor = 0.0;
510 _marking_task_overhead = 1.0;
511 }
512
513 assert(ConcGCThreads > 0, "Should have been set");
514 _parallel_marking_threads = ConcGCThreads;
515 _max_parallel_marking_threads = _parallel_marking_threads;
516
517 _parallel_workers = new WorkGang("G1 Marker",
518 _max_parallel_marking_threads, false, true);
519 if (_parallel_workers == NULL) {
520 vm_exit_during_initialization("Failed necessary allocation.");
521 } else {
522 _parallel_workers->initialize_workers();
523 }
524
525 if (FLAG_IS_DEFAULT(MarkStackSize)) {
526 size_t mark_stack_size =
527 MIN2(MarkStackSizeMax,
528 MAX2(MarkStackSize, (size_t) (parallel_marking_threads() * TASKQUEUE_SIZE)));
529 // Verify that the calculated value for MarkStackSize is in range.
530 // It would be nice to use the private utility routine from Arguments.
531 if (!(mark_stack_size >= 1 && mark_stack_size <= MarkStackSizeMax)) {
532 warning("Invalid value calculated for MarkStackSize (" SIZE_FORMAT "): "
533 "must be between 1 and " SIZE_FORMAT,
534 mark_stack_size, MarkStackSizeMax);
535 return;
536 }
537 FLAG_SET_ERGO(size_t, MarkStackSize, mark_stack_size);
538 } else {
539 // Verify MarkStackSize is in range.
540 if (FLAG_IS_CMDLINE(MarkStackSize)) {
541 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
542 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
543 warning("Invalid value specified for MarkStackSize (" SIZE_FORMAT "): "
544 "must be between 1 and " SIZE_FORMAT,
545 MarkStackSize, MarkStackSizeMax);
546 return;
547 }
548 } else if (FLAG_IS_CMDLINE(MarkStackSizeMax)) {
549 if (!(MarkStackSize >= 1 && MarkStackSize <= MarkStackSizeMax)) {
550 warning("Invalid value specified for MarkStackSize (" SIZE_FORMAT ")"
551 " or for MarkStackSizeMax (" SIZE_FORMAT ")",
552 MarkStackSize, MarkStackSizeMax);
553 return;
554 }
555 }
556 }
557 }
558
559 if (!_markStack.allocate(MarkStackSize)) {
560 warning("Failed to allocate CM marking stack");
561 return;
562 }
563
564 _tasks = NEW_C_HEAP_ARRAY(CMTask*, _max_worker_id, mtGC);
565 _accum_task_vtime = NEW_C_HEAP_ARRAY(double, _max_worker_id, mtGC);
566
567 _count_card_bitmaps = NEW_C_HEAP_ARRAY(BitMap, _max_worker_id, mtGC);
568 _count_marked_bytes = NEW_C_HEAP_ARRAY(size_t*, _max_worker_id, mtGC);
569
570 BitMap::idx_t card_bm_size = _card_bm.size();
571
572 // so that the assertion in MarkingTaskQueue::task_queue doesn't fail
573 _active_tasks = _max_worker_id;
574
575 uint max_regions = _g1h->max_regions();
576 for (uint i = 0; i < _max_worker_id; ++i) {
577 CMTaskQueue* task_queue = new CMTaskQueue();
578 task_queue->initialize();
579 _task_queues->register_queue(i, task_queue);
580
581 _count_card_bitmaps[i] = BitMap(card_bm_size, false);
582 _count_marked_bytes[i] = NEW_C_HEAP_ARRAY(size_t, max_regions, mtGC);
583
584 _tasks[i] = new CMTask(i, this,
585 _count_marked_bytes[i],
586 &_count_card_bitmaps[i],
587 task_queue, _task_queues);
588
589 _accum_task_vtime[i] = 0.0;
590 }
591
592 // Calculate the card number for the bottom of the heap. Used
593 // in biasing indexes into the accounting card bitmaps.
594 _heap_bottom_card_num =
595 intptr_t(uintptr_t(_g1h->reserved_region().start()) >>
596 CardTableModRefBS::card_shift);
597
598 // Clear all the liveness counting data
599 clear_all_count_data();
600
601 // so that the call below can read a sensible value
602 _heap_start = g1h->reserved_region().start();
603 set_non_marking_state();
604 _completed_initialization = true;
605 }
606
607 void ConcurrentMark::reset() {
608 // Starting values for these two. This should be called in a STW
609 // phase.
610 MemRegion reserved = _g1h->g1_reserved();
611 _heap_start = reserved.start();
612 _heap_end = reserved.end();
613
614 // Separated the asserts so that we know which one fires.
615 assert(_heap_start != NULL, "heap bounds should look ok");
616 assert(_heap_end != NULL, "heap bounds should look ok");
617 assert(_heap_start < _heap_end, "heap bounds should look ok");
618
619 // Reset all the marking data structures and any necessary flags
620 reset_marking_state();
621
622 // We do reset all of them, since different phases will use
623 // different number of active threads. So, it's easiest to have all
624 // of them ready.
625 for (uint i = 0; i < _max_worker_id; ++i) {
626 _tasks[i]->reset(_nextMarkBitMap);
627 }
628
629 // we need this to make sure that the flag is on during the evac
630 // pause with initial mark piggy-backed
631 set_concurrent_marking_in_progress();
632 }
633
634
635 void ConcurrentMark::reset_marking_state(bool clear_overflow) {
636 _markStack.set_should_expand();
637 _markStack.setEmpty(); // Also clears the _markStack overflow flag
638 if (clear_overflow) {
639 clear_has_overflown();
640 } else {
641 assert(has_overflown(), "pre-condition");
642 }
643 _finger = _heap_start;
644
645 for (uint i = 0; i < _max_worker_id; ++i) {
646 CMTaskQueue* queue = _task_queues->queue(i);
647 queue->set_empty();
648 }
649 }
650
651 void ConcurrentMark::set_concurrency(uint active_tasks) {
652 assert(active_tasks <= _max_worker_id, "we should not have more");
653
654 _active_tasks = active_tasks;
655 // Need to update the three data structures below according to the
656 // number of active threads for this phase.
657 _terminator = ParallelTaskTerminator((int) active_tasks, _task_queues);
658 _first_overflow_barrier_sync.set_n_workers((int) active_tasks);
659 _second_overflow_barrier_sync.set_n_workers((int) active_tasks);
660 }
661
662 void ConcurrentMark::set_concurrency_and_phase(uint active_tasks, bool concurrent) {
663 set_concurrency(active_tasks);
664
665 _concurrent = concurrent;
666 // We propagate this to all tasks, not just the active ones.
667 for (uint i = 0; i < _max_worker_id; ++i)
668 _tasks[i]->set_concurrent(concurrent);
669
670 if (concurrent) {
671 set_concurrent_marking_in_progress();
672 } else {
673 // We currently assume that the concurrent flag has been set to
674 // false before we start remark. At this point we should also be
675 // in a STW phase.
676 assert(!concurrent_marking_in_progress(), "invariant");
677 assert(out_of_regions(),
678 "only way to get here: _finger: " PTR_FORMAT ", _heap_end: " PTR_FORMAT,
679 p2i(_finger), p2i(_heap_end));
680 }
681 }
682
683 void ConcurrentMark::set_non_marking_state() {
684 // We set the global marking state to some default values when we're
685 // not doing marking.
686 reset_marking_state();
687 _active_tasks = 0;
688 clear_concurrent_marking_in_progress();
689 }
690
691 ConcurrentMark::~ConcurrentMark() {
692 // The ConcurrentMark instance is never freed.
693 ShouldNotReachHere();
694 }
695
696 void ConcurrentMark::clearNextBitmap() {
697 G1CollectedHeap* g1h = G1CollectedHeap::heap();
698
699 // Make sure that the concurrent mark thread looks to still be in
700 // the current cycle.
701 guarantee(cmThread()->during_cycle(), "invariant");
702
703 // We are finishing up the current cycle by clearing the next
704 // marking bitmap and getting it ready for the next cycle. During
705 // this time no other cycle can start. So, let's make sure that this
706 // is the case.
707 guarantee(!g1h->collector_state()->mark_in_progress(), "invariant");
708
709 ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */);
710 ParClearNextMarkBitmapTask task(&cl, parallel_marking_threads(), true);
711 _parallel_workers->run_task(&task);
712
713 // Clear the liveness counting data. If the marking has been aborted, the abort()
714 // call already did that.
715 if (cl.complete()) {
716 clear_all_count_data();
717 }
718
719 // Repeat the asserts from above.
720 guarantee(cmThread()->during_cycle(), "invariant");
721 guarantee(!g1h->collector_state()->mark_in_progress(), "invariant");
722 }
723
724 class CheckBitmapClearHRClosure : public HeapRegionClosure {
725 CMBitMap* _bitmap;
726 bool _error;
727 public:
728 CheckBitmapClearHRClosure(CMBitMap* bitmap) : _bitmap(bitmap) {
729 }
730
731 virtual bool doHeapRegion(HeapRegion* r) {
732 // This closure can be called concurrently to the mutator, so we must make sure
733 // that the result of the getNextMarkedWordAddress() call is compared to the
734 // value passed to it as limit to detect any found bits.
735 // end never changes in G1.
736 HeapWord* end = r->end();
737 return _bitmap->getNextMarkedWordAddress(r->bottom(), end) != end;
738 }
739 };
740
741 bool ConcurrentMark::nextMarkBitmapIsClear() {
742 CheckBitmapClearHRClosure cl(_nextMarkBitMap);
743 _g1h->heap_region_iterate(&cl);
744 return cl.complete();
745 }
746
747 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
748 public:
749 bool doHeapRegion(HeapRegion* r) {
750 r->note_start_of_marking();
751 return false;
752 }
753 };
754
755 void ConcurrentMark::checkpointRootsInitialPre() {
756 G1CollectedHeap* g1h = G1CollectedHeap::heap();
757 G1CollectorPolicy* g1p = g1h->g1_policy();
758
759 _has_aborted = false;
760
761 // Initialize marking structures. This has to be done in a STW phase.
762 reset();
763
764 // For each region note start of marking.
765 NoteStartOfMarkHRClosure startcl;
766 g1h->heap_region_iterate(&startcl);
767 }
768
769
770 void ConcurrentMark::checkpointRootsInitialPost() {
771 G1CollectedHeap* g1h = G1CollectedHeap::heap();
772
773 // Start Concurrent Marking weak-reference discovery.
774 ReferenceProcessor* rp = g1h->ref_processor_cm();
775 // enable ("weak") refs discovery
776 rp->enable_discovery();
777 rp->setup_policy(false); // snapshot the soft ref policy to be used in this cycle
778
779 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
780 // This is the start of the marking cycle, we're expected all
781 // threads to have SATB queues with active set to false.
782 satb_mq_set.set_active_all_threads(true, /* new active value */
783 false /* expected_active */);
784
785 _root_regions.prepare_for_scan();
786
787 // update_g1_committed() will be called at the end of an evac pause
788 // when marking is on. So, it's also called at the end of the
789 // initial-mark pause to update the heap end, if the heap expands
790 // during it. No need to call it here.
791 }
792
793 /*
794 * Notice that in the next two methods, we actually leave the STS
795 * during the barrier sync and join it immediately afterwards. If we
796 * do not do this, the following deadlock can occur: one thread could
797 * be in the barrier sync code, waiting for the other thread to also
798 * sync up, whereas another one could be trying to yield, while also
799 * waiting for the other threads to sync up too.
800 *
801 * Note, however, that this code is also used during remark and in
802 * this case we should not attempt to leave / enter the STS, otherwise
803 * we'll either hit an assert (debug / fastdebug) or deadlock
804 * (product). So we should only leave / enter the STS if we are
805 * operating concurrently.
806 *
807 * Because the thread that does the sync barrier has left the STS, it
808 * is possible to be suspended for a Full GC or an evacuation pause
809 * could occur. This is actually safe, since the entering the sync
810 * barrier is one of the last things do_marking_step() does, and it
811 * doesn't manipulate any data structures afterwards.
812 */
813
814 void ConcurrentMark::enter_first_sync_barrier(uint worker_id) {
815 bool barrier_aborted;
816 {
817 SuspendibleThreadSetLeaver sts_leave(concurrent());
818 barrier_aborted = !_first_overflow_barrier_sync.enter();
819 }
820
821 // at this point everyone should have synced up and not be doing any
822 // more work
823
824 if (barrier_aborted) {
825 // If the barrier aborted we ignore the overflow condition and
826 // just abort the whole marking phase as quickly as possible.
827 return;
828 }
829
830 // If we're executing the concurrent phase of marking, reset the marking
831 // state; otherwise the marking state is reset after reference processing,
832 // during the remark pause.
833 // If we reset here as a result of an overflow during the remark we will
834 // see assertion failures from any subsequent set_concurrency_and_phase()
835 // calls.
836 if (concurrent()) {
837 // let the task associated with with worker 0 do this
838 if (worker_id == 0) {
839 // task 0 is responsible for clearing the global data structures
840 // We should be here because of an overflow. During STW we should
841 // not clear the overflow flag since we rely on it being true when
842 // we exit this method to abort the pause and restart concurrent
843 // marking.
844 reset_marking_state(true /* clear_overflow */);
845
846 log_info(gc)("Concurrent Mark reset for overflow");
847 }
848 }
849
850 // after this, each task should reset its own data structures then
851 // then go into the second barrier
852 }
853
854 void ConcurrentMark::enter_second_sync_barrier(uint worker_id) {
855 SuspendibleThreadSetLeaver sts_leave(concurrent());
856 _second_overflow_barrier_sync.enter();
857
858 // at this point everything should be re-initialized and ready to go
859 }
860
861 class CMConcurrentMarkingTask: public AbstractGangTask {
862 private:
863 ConcurrentMark* _cm;
864 ConcurrentMarkThread* _cmt;
865
866 public:
867 void work(uint worker_id) {
868 assert(Thread::current()->is_ConcurrentGC_thread(),
869 "this should only be done by a conc GC thread");
870 ResourceMark rm;
871
872 double start_vtime = os::elapsedVTime();
873
874 {
875 SuspendibleThreadSetJoiner sts_join;
876
877 assert(worker_id < _cm->active_tasks(), "invariant");
878 CMTask* the_task = _cm->task(worker_id);
879 the_task->record_start_time();
880 if (!_cm->has_aborted()) {
881 do {
882 double start_vtime_sec = os::elapsedVTime();
883 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
884
885 the_task->do_marking_step(mark_step_duration_ms,
886 true /* do_termination */,
887 false /* is_serial*/);
888
889 double end_vtime_sec = os::elapsedVTime();
890 double elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
891 _cm->clear_has_overflown();
892
893 _cm->do_yield_check(worker_id);
894
895 jlong sleep_time_ms;
896 if (!_cm->has_aborted() && the_task->has_aborted()) {
897 sleep_time_ms =
898 (jlong) (elapsed_vtime_sec * _cm->sleep_factor() * 1000.0);
899 {
900 SuspendibleThreadSetLeaver sts_leave;
901 os::sleep(Thread::current(), sleep_time_ms, false);
902 }
903 }
904 } while (!_cm->has_aborted() && the_task->has_aborted());
905 }
906 the_task->record_end_time();
907 guarantee(!the_task->has_aborted() || _cm->has_aborted(), "invariant");
908 }
909
910 double end_vtime = os::elapsedVTime();
911 _cm->update_accum_task_vtime(worker_id, end_vtime - start_vtime);
912 }
913
914 CMConcurrentMarkingTask(ConcurrentMark* cm,
915 ConcurrentMarkThread* cmt) :
916 AbstractGangTask("Concurrent Mark"), _cm(cm), _cmt(cmt) { }
917
918 ~CMConcurrentMarkingTask() { }
919 };
920
921 // Calculates the number of active workers for a concurrent
922 // phase.
923 uint ConcurrentMark::calc_parallel_marking_threads() {
924 uint n_conc_workers = 0;
925 if (!UseDynamicNumberOfGCThreads ||
926 (!FLAG_IS_DEFAULT(ConcGCThreads) &&
927 !ForceDynamicNumberOfGCThreads)) {
928 n_conc_workers = max_parallel_marking_threads();
929 } else {
930 n_conc_workers =
931 AdaptiveSizePolicy::calc_default_active_workers(
932 max_parallel_marking_threads(),
933 1, /* Minimum workers */
934 parallel_marking_threads(),
935 Threads::number_of_non_daemon_threads());
936 // Don't scale down "n_conc_workers" by scale_parallel_threads() because
937 // that scaling has already gone into "_max_parallel_marking_threads".
938 }
939 assert(n_conc_workers > 0, "Always need at least 1");
940 return n_conc_workers;
941 }
942
943 void ConcurrentMark::scanRootRegion(HeapRegion* hr, uint worker_id) {
944 // Currently, only survivors can be root regions.
945 assert(hr->next_top_at_mark_start() == hr->bottom(), "invariant");
946 G1RootRegionScanClosure cl(_g1h, this, worker_id);
947
948 const uintx interval = PrefetchScanIntervalInBytes;
949 HeapWord* curr = hr->bottom();
950 const HeapWord* end = hr->top();
951 while (curr < end) {
952 Prefetch::read(curr, interval);
953 oop obj = oop(curr);
954 int size = obj->oop_iterate_size(&cl);
955 assert(size == obj->size(), "sanity");
956 curr += size;
957 }
958 }
959
960 class CMRootRegionScanTask : public AbstractGangTask {
961 private:
962 ConcurrentMark* _cm;
963
964 public:
965 CMRootRegionScanTask(ConcurrentMark* cm) :
966 AbstractGangTask("Root Region Scan"), _cm(cm) { }
967
968 void work(uint worker_id) {
969 assert(Thread::current()->is_ConcurrentGC_thread(),
970 "this should only be done by a conc GC thread");
971
972 CMRootRegions* root_regions = _cm->root_regions();
973 HeapRegion* hr = root_regions->claim_next();
974 while (hr != NULL) {
975 _cm->scanRootRegion(hr, worker_id);
976 hr = root_regions->claim_next();
977 }
978 }
979 };
980
981 void ConcurrentMark::scanRootRegions() {
982 // Start of concurrent marking.
983 ClassLoaderDataGraph::clear_claimed_marks();
984
985 // scan_in_progress() will have been set to true only if there was
986 // at least one root region to scan. So, if it's false, we
987 // should not attempt to do any further work.
988 if (root_regions()->scan_in_progress()) {
989 GCTraceConcTime(Info, gc) tt("Concurrent Root Region Scan");
990
991 _parallel_marking_threads = calc_parallel_marking_threads();
992 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
993 "Maximum number of marking threads exceeded");
994 uint active_workers = MAX2(1U, parallel_marking_threads());
995
996 CMRootRegionScanTask task(this);
997 _parallel_workers->set_active_workers(active_workers);
998 _parallel_workers->run_task(&task);
999
1000 // It's possible that has_aborted() is true here without actually
1001 // aborting the survivor scan earlier. This is OK as it's
1002 // mainly used for sanity checking.
1003 root_regions()->scan_finished();
1004 }
1005 }
1006
1007 void ConcurrentMark::register_concurrent_phase_start(const char* title) {
1008 assert(!_concurrent_phase_started, "Sanity");
1009 _concurrent_phase_started = true;
1010 _g1h->gc_timer_cm()->register_gc_concurrent_start(title);
1011 }
1012
1013 void ConcurrentMark::register_concurrent_phase_end() {
1014 if (_concurrent_phase_started) {
1015 _concurrent_phase_started = false;
1016 _g1h->gc_timer_cm()->register_gc_concurrent_end();
1017 }
1018 }
1019
1020 void ConcurrentMark::markFromRoots() {
1021 // we might be tempted to assert that:
1022 // assert(asynch == !SafepointSynchronize::is_at_safepoint(),
1023 // "inconsistent argument?");
1024 // However that wouldn't be right, because it's possible that
1025 // a safepoint is indeed in progress as a younger generation
1026 // stop-the-world GC happens even as we mark in this generation.
1027
1028 _restart_for_overflow = false;
1029
1030 // _g1h has _n_par_threads
1031 _parallel_marking_threads = calc_parallel_marking_threads();
1032 assert(parallel_marking_threads() <= max_parallel_marking_threads(),
1033 "Maximum number of marking threads exceeded");
1034
1035 uint active_workers = MAX2(1U, parallel_marking_threads());
1036 assert(active_workers > 0, "Should have been set");
1037
1038 // Parallel task terminator is set in "set_concurrency_and_phase()"
1039 set_concurrency_and_phase(active_workers, true /* concurrent */);
1040
1041 CMConcurrentMarkingTask markingTask(this, cmThread());
1042 _parallel_workers->set_active_workers(active_workers);
1043 _parallel_workers->run_task(&markingTask);
1044 print_stats();
1045 }
1046
1047 void ConcurrentMark::checkpointRootsFinal(bool clear_all_soft_refs) {
1048 // world is stopped at this checkpoint
1049 assert(SafepointSynchronize::is_at_safepoint(),
1050 "world should be stopped");
1051
1052 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1053
1054 // If a full collection has happened, we shouldn't do this.
1055 if (has_aborted()) {
1056 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1057 return;
1058 }
1059
1060 SvcGCMarker sgcm(SvcGCMarker::OTHER);
1061
1062 if (VerifyDuringGC) {
1063 HandleMark hm; // handle scope
1064 g1h->prepare_for_verify();
1065 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1066 }
1067 g1h->check_bitmaps("Remark Start");
1068
1069 G1CollectorPolicy* g1p = g1h->g1_policy();
1070 g1p->record_concurrent_mark_remark_start();
1071
1072 double start = os::elapsedTime();
1073
1074 checkpointRootsFinalWork();
1075
1076 double mark_work_end = os::elapsedTime();
1077
1078 weakRefsWork(clear_all_soft_refs);
1079
1080 if (has_overflown()) {
1081 // Oops. We overflowed. Restart concurrent marking.
1082 _restart_for_overflow = true;
1083 log_develop_trace(gc)("Remark led to restart for overflow.");
1084
1085 // Verify the heap w.r.t. the previous marking bitmap.
1086 if (VerifyDuringGC) {
1087 HandleMark hm; // handle scope
1088 g1h->prepare_for_verify();
1089 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (overflow)");
1090 }
1091
1092 // Clear the marking state because we will be restarting
1093 // marking due to overflowing the global mark stack.
1094 reset_marking_state();
1095 } else {
1096 {
1097 GCTraceTime(Debug, gc) trace("GC Aggregate Data", g1h->gc_timer_cm());
1098
1099 // Aggregate the per-task counting data that we have accumulated
1100 // while marking.
1101 aggregate_count_data();
1102 }
1103
1104 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
1105 // We're done with marking.
1106 // This is the end of the marking cycle, we're expected all
1107 // threads to have SATB queues with active set to true.
1108 satb_mq_set.set_active_all_threads(false, /* new active value */
1109 true /* expected_active */);
1110
1111 if (VerifyDuringGC) {
1112 HandleMark hm; // handle scope
1113 g1h->prepare_for_verify();
1114 Universe::verify(VerifyOption_G1UseNextMarking, "During GC (after)");
1115 }
1116 g1h->check_bitmaps("Remark End");
1117 assert(!restart_for_overflow(), "sanity");
1118 // Completely reset the marking state since marking completed
1119 set_non_marking_state();
1120 }
1121
1122 // Expand the marking stack, if we have to and if we can.
1123 if (_markStack.should_expand()) {
1124 _markStack.expand();
1125 }
1126
1127 // Statistics
1128 double now = os::elapsedTime();
1129 _remark_mark_times.add((mark_work_end - start) * 1000.0);
1130 _remark_weak_ref_times.add((now - mark_work_end) * 1000.0);
1131 _remark_times.add((now - start) * 1000.0);
1132
1133 g1p->record_concurrent_mark_remark_end();
1134
1135 G1CMIsAliveClosure is_alive(g1h);
1136 g1h->gc_tracer_cm()->report_object_count_after_gc(&is_alive);
1137 }
1138
1139 // Base class of the closures that finalize and verify the
1140 // liveness counting data.
1141 class CMCountDataClosureBase: public HeapRegionClosure {
1142 protected:
1143 G1CollectedHeap* _g1h;
1144 ConcurrentMark* _cm;
1145 CardTableModRefBS* _ct_bs;
1146
1147 BitMap* _region_bm;
1148 BitMap* _card_bm;
1149
1150 // Takes a region that's not empty (i.e., it has at least one
1151 // live object in it and sets its corresponding bit on the region
1152 // bitmap to 1.
1153 void set_bit_for_region(HeapRegion* hr) {
1154 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1155 _region_bm->par_at_put(index, true);
1156 }
1157
1158 public:
1159 CMCountDataClosureBase(G1CollectedHeap* g1h,
1160 BitMap* region_bm, BitMap* card_bm):
1161 _g1h(g1h), _cm(g1h->concurrent_mark()),
1162 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
1163 _region_bm(region_bm), _card_bm(card_bm) { }
1164 };
1165
1166 // Closure that calculates the # live objects per region. Used
1167 // for verification purposes during the cleanup pause.
1168 class CalcLiveObjectsClosure: public CMCountDataClosureBase {
1169 CMBitMapRO* _bm;
1170 size_t _region_marked_bytes;
1171
1172 public:
1173 CalcLiveObjectsClosure(CMBitMapRO *bm, G1CollectedHeap* g1h,
1174 BitMap* region_bm, BitMap* card_bm) :
1175 CMCountDataClosureBase(g1h, region_bm, card_bm),
1176 _bm(bm), _region_marked_bytes(0) { }
1177
1178 bool doHeapRegion(HeapRegion* hr) {
1179 HeapWord* ntams = hr->next_top_at_mark_start();
1180 HeapWord* start = hr->bottom();
1181
1182 assert(start <= hr->end() && start <= ntams && ntams <= hr->end(),
1183 "Preconditions not met - "
1184 "start: " PTR_FORMAT ", ntams: " PTR_FORMAT ", end: " PTR_FORMAT,
1185 p2i(start), p2i(ntams), p2i(hr->end()));
1186
1187 // Find the first marked object at or after "start".
1188 start = _bm->getNextMarkedWordAddress(start, ntams);
1189
1190 size_t marked_bytes = 0;
1191
1192 while (start < ntams) {
1193 oop obj = oop(start);
1194 int obj_sz = obj->size();
1195 HeapWord* obj_end = start + obj_sz;
1196
1197 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
1198 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(obj_end);
1199
1200 // Note: if we're looking at the last region in heap - obj_end
1201 // could be actually just beyond the end of the heap; end_idx
1202 // will then correspond to a (non-existent) card that is also
1203 // just beyond the heap.
1204 if (_g1h->is_in_g1_reserved(obj_end) && !_ct_bs->is_card_aligned(obj_end)) {
1205 // end of object is not card aligned - increment to cover
1206 // all the cards spanned by the object
1207 end_idx += 1;
1208 }
1209
1210 // Set the bits in the card BM for the cards spanned by this object.
1211 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1212
1213 // Add the size of this object to the number of marked bytes.
1214 marked_bytes += (size_t)obj_sz * HeapWordSize;
1215
1216 // This will happen if we are handling a humongous object that spans
1217 // several heap regions.
1218 if (obj_end > hr->end()) {
1219 break;
1220 }
1221 // Find the next marked object after this one.
1222 start = _bm->getNextMarkedWordAddress(obj_end, ntams);
1223 }
1224
1225 // Mark the allocated-since-marking portion...
1226 HeapWord* top = hr->top();
1227 if (ntams < top) {
1228 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1229 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1230
1231 // Note: if we're looking at the last region in heap - top
1232 // could be actually just beyond the end of the heap; end_idx
1233 // will then correspond to a (non-existent) card that is also
1234 // just beyond the heap.
1235 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1236 // end of object is not card aligned - increment to cover
1237 // all the cards spanned by the object
1238 end_idx += 1;
1239 }
1240 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1241
1242 // This definitely means the region has live objects.
1243 set_bit_for_region(hr);
1244 }
1245
1246 // Update the live region bitmap.
1247 if (marked_bytes > 0) {
1248 set_bit_for_region(hr);
1249 }
1250
1251 // Set the marked bytes for the current region so that
1252 // it can be queried by a calling verification routine
1253 _region_marked_bytes = marked_bytes;
1254
1255 return false;
1256 }
1257
1258 size_t region_marked_bytes() const { return _region_marked_bytes; }
1259 };
1260
1261 // Heap region closure used for verifying the counting data
1262 // that was accumulated concurrently and aggregated during
1263 // the remark pause. This closure is applied to the heap
1264 // regions during the STW cleanup pause.
1265
1266 class VerifyLiveObjectDataHRClosure: public HeapRegionClosure {
1267 G1CollectedHeap* _g1h;
1268 ConcurrentMark* _cm;
1269 CalcLiveObjectsClosure _calc_cl;
1270 BitMap* _region_bm; // Region BM to be verified
1271 BitMap* _card_bm; // Card BM to be verified
1272
1273 BitMap* _exp_region_bm; // Expected Region BM values
1274 BitMap* _exp_card_bm; // Expected card BM values
1275
1276 int _failures;
1277
1278 public:
1279 VerifyLiveObjectDataHRClosure(G1CollectedHeap* g1h,
1280 BitMap* region_bm,
1281 BitMap* card_bm,
1282 BitMap* exp_region_bm,
1283 BitMap* exp_card_bm) :
1284 _g1h(g1h), _cm(g1h->concurrent_mark()),
1285 _calc_cl(_cm->nextMarkBitMap(), g1h, exp_region_bm, exp_card_bm),
1286 _region_bm(region_bm), _card_bm(card_bm),
1287 _exp_region_bm(exp_region_bm), _exp_card_bm(exp_card_bm),
1288 _failures(0) { }
1289
1290 int failures() const { return _failures; }
1291
1292 bool doHeapRegion(HeapRegion* hr) {
1293 int failures = 0;
1294
1295 // Call the CalcLiveObjectsClosure to walk the marking bitmap for
1296 // this region and set the corresponding bits in the expected region
1297 // and card bitmaps.
1298 bool res = _calc_cl.doHeapRegion(hr);
1299 assert(res == false, "should be continuing");
1300
1301 // Verify the marked bytes for this region.
1302 size_t exp_marked_bytes = _calc_cl.region_marked_bytes();
1303 size_t act_marked_bytes = hr->next_marked_bytes();
1304
1305 if (exp_marked_bytes > act_marked_bytes) {
1306 if (hr->is_starts_humongous()) {
1307 // For start_humongous regions, the size of the whole object will be
1308 // in exp_marked_bytes.
1309 HeapRegion* region = hr;
1310 int num_regions;
1311 for (num_regions = 0; region != NULL; num_regions++) {
1312 region = _g1h->next_region_in_humongous(region);
1313 }
1314 if ((num_regions-1) * HeapRegion::GrainBytes >= exp_marked_bytes) {
1315 failures += 1;
1316 } else if (num_regions * HeapRegion::GrainBytes < exp_marked_bytes) {
1317 failures += 1;
1318 }
1319 } else {
1320 // We're not OK if expected marked bytes > actual marked bytes. It means
1321 // we have missed accounting some objects during the actual marking.
1322 failures += 1;
1323 }
1324 }
1325
1326 // Verify the bit, for this region, in the actual and expected
1327 // (which was just calculated) region bit maps.
1328 // We're not OK if the bit in the calculated expected region
1329 // bitmap is set and the bit in the actual region bitmap is not.
1330 BitMap::idx_t index = (BitMap::idx_t) hr->hrm_index();
1331
1332 bool expected = _exp_region_bm->at(index);
1333 bool actual = _region_bm->at(index);
1334 if (expected && !actual) {
1335 failures += 1;
1336 }
1337
1338 // Verify that the card bit maps for the cards spanned by the current
1339 // region match. We have an error if we have a set bit in the expected
1340 // bit map and the corresponding bit in the actual bitmap is not set.
1341
1342 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(hr->bottom());
1343 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(hr->top());
1344
1345 for (BitMap::idx_t i = start_idx; i < end_idx; i+=1) {
1346 expected = _exp_card_bm->at(i);
1347 actual = _card_bm->at(i);
1348
1349 if (expected && !actual) {
1350 failures += 1;
1351 }
1352 }
1353
1354 _failures += failures;
1355
1356 // We could stop iteration over the heap when we
1357 // find the first violating region by returning true.
1358 return false;
1359 }
1360 };
1361
1362 class G1ParVerifyFinalCountTask: public AbstractGangTask {
1363 protected:
1364 G1CollectedHeap* _g1h;
1365 ConcurrentMark* _cm;
1366 BitMap* _actual_region_bm;
1367 BitMap* _actual_card_bm;
1368
1369 uint _n_workers;
1370
1371 BitMap* _expected_region_bm;
1372 BitMap* _expected_card_bm;
1373
1374 int _failures;
1375
1376 HeapRegionClaimer _hrclaimer;
1377
1378 public:
1379 G1ParVerifyFinalCountTask(G1CollectedHeap* g1h,
1380 BitMap* region_bm, BitMap* card_bm,
1381 BitMap* expected_region_bm, BitMap* expected_card_bm)
1382 : AbstractGangTask("G1 verify final counting"),
1383 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1384 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1385 _expected_region_bm(expected_region_bm), _expected_card_bm(expected_card_bm),
1386 _failures(0),
1387 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1388 assert(VerifyDuringGC, "don't call this otherwise");
1389 assert(_expected_card_bm->size() == _actual_card_bm->size(), "sanity");
1390 assert(_expected_region_bm->size() == _actual_region_bm->size(), "sanity");
1391 }
1392
1393 void work(uint worker_id) {
1394 assert(worker_id < _n_workers, "invariant");
1395
1396 VerifyLiveObjectDataHRClosure verify_cl(_g1h,
1397 _actual_region_bm, _actual_card_bm,
1398 _expected_region_bm,
1399 _expected_card_bm);
1400
1401 _g1h->heap_region_par_iterate(&verify_cl, worker_id, &_hrclaimer);
1402
1403 Atomic::add(verify_cl.failures(), &_failures);
1404 }
1405
1406 int failures() const { return _failures; }
1407 };
1408
1409 // Closure that finalizes the liveness counting data.
1410 // Used during the cleanup pause.
1411 // Sets the bits corresponding to the interval [NTAMS, top]
1412 // (which contains the implicitly live objects) in the
1413 // card liveness bitmap. Also sets the bit for each region,
1414 // containing live data, in the region liveness bitmap.
1415
1416 class FinalCountDataUpdateClosure: public CMCountDataClosureBase {
1417 public:
1418 FinalCountDataUpdateClosure(G1CollectedHeap* g1h,
1419 BitMap* region_bm,
1420 BitMap* card_bm) :
1421 CMCountDataClosureBase(g1h, region_bm, card_bm) { }
1422
1423 bool doHeapRegion(HeapRegion* hr) {
1424 HeapWord* ntams = hr->next_top_at_mark_start();
1425 HeapWord* top = hr->top();
1426
1427 assert(hr->bottom() <= ntams && ntams <= hr->end(), "Preconditions.");
1428
1429 // Mark the allocated-since-marking portion...
1430 if (ntams < top) {
1431 // This definitely means the region has live objects.
1432 set_bit_for_region(hr);
1433
1434 // Now set the bits in the card bitmap for [ntams, top)
1435 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(ntams);
1436 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(top);
1437
1438 // Note: if we're looking at the last region in heap - top
1439 // could be actually just beyond the end of the heap; end_idx
1440 // will then correspond to a (non-existent) card that is also
1441 // just beyond the heap.
1442 if (_g1h->is_in_g1_reserved(top) && !_ct_bs->is_card_aligned(top)) {
1443 // end of object is not card aligned - increment to cover
1444 // all the cards spanned by the object
1445 end_idx += 1;
1446 }
1447
1448 assert(end_idx <= _card_bm->size(),
1449 "oob: end_idx= " SIZE_FORMAT ", bitmap size= " SIZE_FORMAT,
1450 end_idx, _card_bm->size());
1451 assert(start_idx < _card_bm->size(),
1452 "oob: start_idx= " SIZE_FORMAT ", bitmap size= " SIZE_FORMAT,
1453 start_idx, _card_bm->size());
1454
1455 _cm->set_card_bitmap_range(_card_bm, start_idx, end_idx, true /* is_par */);
1456 }
1457
1458 // Set the bit for the region if it contains live data
1459 if (hr->next_marked_bytes() > 0) {
1460 set_bit_for_region(hr);
1461 }
1462
1463 return false;
1464 }
1465 };
1466
1467 class G1ParFinalCountTask: public AbstractGangTask {
1468 protected:
1469 G1CollectedHeap* _g1h;
1470 ConcurrentMark* _cm;
1471 BitMap* _actual_region_bm;
1472 BitMap* _actual_card_bm;
1473
1474 uint _n_workers;
1475 HeapRegionClaimer _hrclaimer;
1476
1477 public:
1478 G1ParFinalCountTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm)
1479 : AbstractGangTask("G1 final counting"),
1480 _g1h(g1h), _cm(_g1h->concurrent_mark()),
1481 _actual_region_bm(region_bm), _actual_card_bm(card_bm),
1482 _n_workers(_g1h->workers()->active_workers()), _hrclaimer(_n_workers) {
1483 }
1484
1485 void work(uint worker_id) {
1486 assert(worker_id < _n_workers, "invariant");
1487
1488 FinalCountDataUpdateClosure final_update_cl(_g1h,
1489 _actual_region_bm,
1490 _actual_card_bm);
1491
1492 _g1h->heap_region_par_iterate(&final_update_cl, worker_id, &_hrclaimer);
1493 }
1494 };
1495
1496 class G1NoteEndOfConcMarkClosure : public HeapRegionClosure {
1497 G1CollectedHeap* _g1;
1498 size_t _freed_bytes;
1499 FreeRegionList* _local_cleanup_list;
1500 uint _old_regions_removed;
1501 uint _humongous_regions_removed;
1502 HRRSCleanupTask* _hrrs_cleanup_task;
1503
1504 public:
1505 G1NoteEndOfConcMarkClosure(G1CollectedHeap* g1,
1506 FreeRegionList* local_cleanup_list,
1507 HRRSCleanupTask* hrrs_cleanup_task) :
1508 _g1(g1),
1509 _freed_bytes(0),
1510 _local_cleanup_list(local_cleanup_list),
1511 _old_regions_removed(0),
1512 _humongous_regions_removed(0),
1513 _hrrs_cleanup_task(hrrs_cleanup_task) { }
1514
1515 size_t freed_bytes() { return _freed_bytes; }
1516 const uint old_regions_removed() { return _old_regions_removed; }
1517 const uint humongous_regions_removed() { return _humongous_regions_removed; }
1518
1519 bool doHeapRegion(HeapRegion *hr) {
1520 if (hr->is_archive()) {
1521 return false;
1522 }
1523 // We use a claim value of zero here because all regions
1524 // were claimed with value 1 in the FinalCount task.
1525 _g1->reset_gc_time_stamps(hr);
1526 hr->note_end_of_marking();
1527
1528 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
1529 _freed_bytes += hr->used();
1530 hr->set_containing_set(NULL);
1531 if (hr->is_humongous()) {
1532 _humongous_regions_removed++;
1533 _g1->free_humongous_region(hr, _local_cleanup_list, true);
1534 } else {
1535 _old_regions_removed++;
1536 _g1->free_region(hr, _local_cleanup_list, true);
1537 }
1538 } else {
1539 hr->rem_set()->do_cleanup_work(_hrrs_cleanup_task);
1540 }
1541
1542 return false;
1543 }
1544 };
1545
1546 class G1ParNoteEndTask: public AbstractGangTask {
1547 friend class G1NoteEndOfConcMarkClosure;
1548
1549 protected:
1550 G1CollectedHeap* _g1h;
1551 FreeRegionList* _cleanup_list;
1552 HeapRegionClaimer _hrclaimer;
1553
1554 public:
1555 G1ParNoteEndTask(G1CollectedHeap* g1h, FreeRegionList* cleanup_list, uint n_workers) :
1556 AbstractGangTask("G1 note end"), _g1h(g1h), _cleanup_list(cleanup_list), _hrclaimer(n_workers) {
1557 }
1558
1559 void work(uint worker_id) {
1560 FreeRegionList local_cleanup_list("Local Cleanup List");
1561 HRRSCleanupTask hrrs_cleanup_task;
1562 G1NoteEndOfConcMarkClosure g1_note_end(_g1h, &local_cleanup_list,
1563 &hrrs_cleanup_task);
1564 _g1h->heap_region_par_iterate(&g1_note_end, worker_id, &_hrclaimer);
1565 assert(g1_note_end.complete(), "Shouldn't have yielded!");
1566
1567 // Now update the lists
1568 _g1h->remove_from_old_sets(g1_note_end.old_regions_removed(), g1_note_end.humongous_regions_removed());
1569 {
1570 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
1571 _g1h->decrement_summary_bytes(g1_note_end.freed_bytes());
1572
1573 // If we iterate over the global cleanup list at the end of
1574 // cleanup to do this printing we will not guarantee to only
1575 // generate output for the newly-reclaimed regions (the list
1576 // might not be empty at the beginning of cleanup; we might
1577 // still be working on its previous contents). So we do the
1578 // printing here, before we append the new regions to the global
1579 // cleanup list.
1580
1581 G1HRPrinter* hr_printer = _g1h->hr_printer();
1582 if (hr_printer->is_active()) {
1583 FreeRegionListIterator iter(&local_cleanup_list);
1584 while (iter.more_available()) {
1585 HeapRegion* hr = iter.get_next();
1586 hr_printer->cleanup(hr);
1587 }
1588 }
1589
1590 _cleanup_list->add_ordered(&local_cleanup_list);
1591 assert(local_cleanup_list.is_empty(), "post-condition");
1592
1593 HeapRegionRemSet::finish_cleanup_task(&hrrs_cleanup_task);
1594 }
1595 }
1596 };
1597
1598 class G1ParScrubRemSetTask: public AbstractGangTask {
1599 protected:
1600 G1RemSet* _g1rs;
1601 BitMap* _region_bm;
1602 BitMap* _card_bm;
1603 HeapRegionClaimer _hrclaimer;
1604
1605 public:
1606 G1ParScrubRemSetTask(G1CollectedHeap* g1h, BitMap* region_bm, BitMap* card_bm, uint n_workers) :
1607 AbstractGangTask("G1 ScrubRS"), _g1rs(g1h->g1_rem_set()), _region_bm(region_bm), _card_bm(card_bm), _hrclaimer(n_workers) {
1608 }
1609
1610 void work(uint worker_id) {
1611 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
1612 }
1613
1614 };
1615
1616 void ConcurrentMark::cleanup() {
1617 // world is stopped at this checkpoint
1618 assert(SafepointSynchronize::is_at_safepoint(),
1619 "world should be stopped");
1620 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1621
1622 // If a full collection has happened, we shouldn't do this.
1623 if (has_aborted()) {
1624 g1h->collector_state()->set_mark_in_progress(false); // So bitmap clearing isn't confused
1625 return;
1626 }
1627
1628 g1h->verify_region_sets_optional();
1629
1630 if (VerifyDuringGC) {
1631 HandleMark hm; // handle scope
1632 g1h->prepare_for_verify();
1633 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (before)");
1634 }
1635 g1h->check_bitmaps("Cleanup Start");
1636
1637 G1CollectorPolicy* g1p = g1h->g1_policy();
1638 g1p->record_concurrent_mark_cleanup_start();
1639
1640 double start = os::elapsedTime();
1641
1642 HeapRegionRemSet::reset_for_cleanup_tasks();
1643
1644 // Do counting once more with the world stopped for good measure.
1645 G1ParFinalCountTask g1_par_count_task(g1h, &_region_bm, &_card_bm);
1646
1647 g1h->workers()->run_task(&g1_par_count_task);
1648
1649 if (VerifyDuringGC) {
1650 // Verify that the counting data accumulated during marking matches
1651 // that calculated by walking the marking bitmap.
1652
1653 // Bitmaps to hold expected values
1654 BitMap expected_region_bm(_region_bm.size(), true);
1655 BitMap expected_card_bm(_card_bm.size(), true);
1656
1657 G1ParVerifyFinalCountTask g1_par_verify_task(g1h,
1658 &_region_bm,
1659 &_card_bm,
1660 &expected_region_bm,
1661 &expected_card_bm);
1662
1663 g1h->workers()->run_task(&g1_par_verify_task);
1664
1665 guarantee(g1_par_verify_task.failures() == 0, "Unexpected accounting failures");
1666 }
1667
1668 size_t start_used_bytes = g1h->used();
1669 g1h->collector_state()->set_mark_in_progress(false);
1670
1671 double count_end = os::elapsedTime();
1672 double this_final_counting_time = (count_end - start);
1673 _total_counting_time += this_final_counting_time;
1674
1675 if (log_is_enabled(Trace, gc, liveness)) {
1676 G1PrintRegionLivenessInfoClosure cl("Post-Marking");
1677 _g1h->heap_region_iterate(&cl);
1678 }
1679
1680 // Install newly created mark bitMap as "prev".
1681 swapMarkBitMaps();
1682
1683 g1h->reset_gc_time_stamp();
1684
1685 uint n_workers = _g1h->workers()->active_workers();
1686
1687 // Note end of marking in all heap regions.
1688 G1ParNoteEndTask g1_par_note_end_task(g1h, &_cleanup_list, n_workers);
1689 g1h->workers()->run_task(&g1_par_note_end_task);
1690 g1h->check_gc_time_stamps();
1691
1692 if (!cleanup_list_is_empty()) {
1693 // The cleanup list is not empty, so we'll have to process it
1694 // concurrently. Notify anyone else that might be wanting free
1695 // regions that there will be more free regions coming soon.
1696 g1h->set_free_regions_coming();
1697 }
1698
1699 // call below, since it affects the metric by which we sort the heap
1700 // regions.
1701 if (G1ScrubRemSets) {
1702 double rs_scrub_start = os::elapsedTime();
1703 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1h, &_region_bm, &_card_bm, n_workers);
1704 g1h->workers()->run_task(&g1_par_scrub_rs_task);
1705
1706 double rs_scrub_end = os::elapsedTime();
1707 double this_rs_scrub_time = (rs_scrub_end - rs_scrub_start);
1708 _total_rs_scrub_time += this_rs_scrub_time;
1709 }
1710
1711 // this will also free any regions totally full of garbage objects,
1712 // and sort the regions.
1713 g1h->g1_policy()->record_concurrent_mark_cleanup_end();
1714
1715 // Statistics.
1716 double end = os::elapsedTime();
1717 _cleanup_times.add((end - start) * 1000.0);
1718
1719 // Clean up will have freed any regions completely full of garbage.
1720 // Update the soft reference policy with the new heap occupancy.
1721 Universe::update_heap_info_at_gc();
1722
1723 if (VerifyDuringGC) {
1724 HandleMark hm; // handle scope
1725 g1h->prepare_for_verify();
1726 Universe::verify(VerifyOption_G1UsePrevMarking, "During GC (after)");
1727 }
1728
1729 g1h->check_bitmaps("Cleanup End");
1730
1731 g1h->verify_region_sets_optional();
1732
1733 // We need to make this be a "collection" so any collection pause that
1734 // races with it goes around and waits for completeCleanup to finish.
1735 g1h->increment_total_collections();
1736
1737 // Clean out dead classes and update Metaspace sizes.
1738 if (ClassUnloadingWithConcurrentMark) {
1739 ClassLoaderDataGraph::purge();
1740 }
1741 MetaspaceGC::compute_new_size();
1742
1743 // We reclaimed old regions so we should calculate the sizes to make
1744 // sure we update the old gen/space data.
1745 g1h->g1mm()->update_sizes();
1746 g1h->allocation_context_stats().update_after_mark();
1747
1748 g1h->trace_heap_after_concurrent_cycle();
1749 }
1750
1751 void ConcurrentMark::completeCleanup() {
1752 if (has_aborted()) return;
1753
1754 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1755
1756 _cleanup_list.verify_optional();
1757 FreeRegionList tmp_free_list("Tmp Free List");
1758
1759 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1760 "cleanup list has %u entries",
1761 _cleanup_list.length());
1762
1763 // No one else should be accessing the _cleanup_list at this point,
1764 // so it is not necessary to take any locks
1765 while (!_cleanup_list.is_empty()) {
1766 HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
1767 assert(hr != NULL, "Got NULL from a non-empty list");
1768 hr->par_clear();
1769 tmp_free_list.add_ordered(hr);
1770
1771 // Instead of adding one region at a time to the secondary_free_list,
1772 // we accumulate them in the local list and move them a few at a
1773 // time. This also cuts down on the number of notify_all() calls
1774 // we do during this process. We'll also append the local list when
1775 // _cleanup_list is empty (which means we just removed the last
1776 // region from the _cleanup_list).
1777 if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
1778 _cleanup_list.is_empty()) {
1779 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [complete cleanup] : "
1780 "appending %u entries to the secondary_free_list, "
1781 "cleanup list still has %u entries",
1782 tmp_free_list.length(),
1783 _cleanup_list.length());
1784
1785 {
1786 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1787 g1h->secondary_free_list_add(&tmp_free_list);
1788 SecondaryFreeList_lock->notify_all();
1789 }
1790 #ifndef PRODUCT
1791 if (G1StressConcRegionFreeing) {
1792 for (uintx i = 0; i < G1StressConcRegionFreeingDelayMillis; ++i) {
1793 os::sleep(Thread::current(), (jlong) 1, false);
1794 }
1795 }
1796 #endif
1797 }
1798 }
1799 assert(tmp_free_list.is_empty(), "post-condition");
1800 }
1801
1802 // Supporting Object and Oop closures for reference discovery
1803 // and processing in during marking
1804
1805 bool G1CMIsAliveClosure::do_object_b(oop obj) {
1806 HeapWord* addr = (HeapWord*)obj;
1807 return addr != NULL &&
1808 (!_g1->is_in_g1_reserved(addr) || !_g1->is_obj_ill(obj));
1809 }
1810
1811 // 'Keep Alive' oop closure used by both serial parallel reference processing.
1812 // Uses the CMTask associated with a worker thread (for serial reference
1813 // processing the CMTask for worker 0 is used) to preserve (mark) and
1814 // trace referent objects.
1815 //
1816 // Using the CMTask and embedded local queues avoids having the worker
1817 // threads operating on the global mark stack. This reduces the risk
1818 // of overflowing the stack - which we would rather avoid at this late
1819 // state. Also using the tasks' local queues removes the potential
1820 // of the workers interfering with each other that could occur if
1821 // operating on the global stack.
1822
1823 class G1CMKeepAliveAndDrainClosure: public OopClosure {
1824 ConcurrentMark* _cm;
1825 CMTask* _task;
1826 int _ref_counter_limit;
1827 int _ref_counter;
1828 bool _is_serial;
1829 public:
1830 G1CMKeepAliveAndDrainClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) :
1831 _cm(cm), _task(task), _is_serial(is_serial),
1832 _ref_counter_limit(G1RefProcDrainInterval) {
1833 assert(_ref_counter_limit > 0, "sanity");
1834 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1835 _ref_counter = _ref_counter_limit;
1836 }
1837
1838 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1839 virtual void do_oop( oop* p) { do_oop_work(p); }
1840
1841 template <class T> void do_oop_work(T* p) {
1842 if (!_cm->has_overflown()) {
1843 oop obj = oopDesc::load_decode_heap_oop(p);
1844 _task->deal_with_reference(obj);
1845 _ref_counter--;
1846
1847 if (_ref_counter == 0) {
1848 // We have dealt with _ref_counter_limit references, pushing them
1849 // and objects reachable from them on to the local stack (and
1850 // possibly the global stack). Call CMTask::do_marking_step() to
1851 // process these entries.
1852 //
1853 // We call CMTask::do_marking_step() in a loop, which we'll exit if
1854 // there's nothing more to do (i.e. we're done with the entries that
1855 // were pushed as a result of the CMTask::deal_with_reference() calls
1856 // above) or we overflow.
1857 //
1858 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
1859 // flag while there may still be some work to do. (See the comment at
1860 // the beginning of CMTask::do_marking_step() for those conditions -
1861 // one of which is reaching the specified time target.) It is only
1862 // when CMTask::do_marking_step() returns without setting the
1863 // has_aborted() flag that the marking step has completed.
1864 do {
1865 double mark_step_duration_ms = G1ConcMarkStepDurationMillis;
1866 _task->do_marking_step(mark_step_duration_ms,
1867 false /* do_termination */,
1868 _is_serial);
1869 } while (_task->has_aborted() && !_cm->has_overflown());
1870 _ref_counter = _ref_counter_limit;
1871 }
1872 }
1873 }
1874 };
1875
1876 // 'Drain' oop closure used by both serial and parallel reference processing.
1877 // Uses the CMTask associated with a given worker thread (for serial
1878 // reference processing the CMtask for worker 0 is used). Calls the
1879 // do_marking_step routine, with an unbelievably large timeout value,
1880 // to drain the marking data structures of the remaining entries
1881 // added by the 'keep alive' oop closure above.
1882
1883 class G1CMDrainMarkingStackClosure: public VoidClosure {
1884 ConcurrentMark* _cm;
1885 CMTask* _task;
1886 bool _is_serial;
1887 public:
1888 G1CMDrainMarkingStackClosure(ConcurrentMark* cm, CMTask* task, bool is_serial) :
1889 _cm(cm), _task(task), _is_serial(is_serial) {
1890 assert(!_is_serial || _task->worker_id() == 0, "only task 0 for serial code");
1891 }
1892
1893 void do_void() {
1894 do {
1895 // We call CMTask::do_marking_step() to completely drain the local
1896 // and global marking stacks of entries pushed by the 'keep alive'
1897 // oop closure (an instance of G1CMKeepAliveAndDrainClosure above).
1898 //
1899 // CMTask::do_marking_step() is called in a loop, which we'll exit
1900 // if there's nothing more to do (i.e. we've completely drained the
1901 // entries that were pushed as a a result of applying the 'keep alive'
1902 // closure to the entries on the discovered ref lists) or we overflow
1903 // the global marking stack.
1904 //
1905 // Note: CMTask::do_marking_step() can set the CMTask::has_aborted()
1906 // flag while there may still be some work to do. (See the comment at
1907 // the beginning of CMTask::do_marking_step() for those conditions -
1908 // one of which is reaching the specified time target.) It is only
1909 // when CMTask::do_marking_step() returns without setting the
1910 // has_aborted() flag that the marking step has completed.
1911
1912 _task->do_marking_step(1000000000.0 /* something very large */,
1913 true /* do_termination */,
1914 _is_serial);
1915 } while (_task->has_aborted() && !_cm->has_overflown());
1916 }
1917 };
1918
1919 // Implementation of AbstractRefProcTaskExecutor for parallel
1920 // reference processing at the end of G1 concurrent marking
1921
1922 class G1CMRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
1923 private:
1924 G1CollectedHeap* _g1h;
1925 ConcurrentMark* _cm;
1926 WorkGang* _workers;
1927 uint _active_workers;
1928
1929 public:
1930 G1CMRefProcTaskExecutor(G1CollectedHeap* g1h,
1931 ConcurrentMark* cm,
1932 WorkGang* workers,
1933 uint n_workers) :
1934 _g1h(g1h), _cm(cm),
1935 _workers(workers), _active_workers(n_workers) { }
1936
1937 // Executes the given task using concurrent marking worker threads.
1938 virtual void execute(ProcessTask& task);
1939 virtual void execute(EnqueueTask& task);
1940 };
1941
1942 class G1CMRefProcTaskProxy: public AbstractGangTask {
1943 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
1944 ProcessTask& _proc_task;
1945 G1CollectedHeap* _g1h;
1946 ConcurrentMark* _cm;
1947
1948 public:
1949 G1CMRefProcTaskProxy(ProcessTask& proc_task,
1950 G1CollectedHeap* g1h,
1951 ConcurrentMark* cm) :
1952 AbstractGangTask("Process reference objects in parallel"),
1953 _proc_task(proc_task), _g1h(g1h), _cm(cm) {
1954 ReferenceProcessor* rp = _g1h->ref_processor_cm();
1955 assert(rp->processing_is_mt(), "shouldn't be here otherwise");
1956 }
1957
1958 virtual void work(uint worker_id) {
1959 ResourceMark rm;
1960 HandleMark hm;
1961 CMTask* task = _cm->task(worker_id);
1962 G1CMIsAliveClosure g1_is_alive(_g1h);
1963 G1CMKeepAliveAndDrainClosure g1_par_keep_alive(_cm, task, false /* is_serial */);
1964 G1CMDrainMarkingStackClosure g1_par_drain(_cm, task, false /* is_serial */);
1965
1966 _proc_task.work(worker_id, g1_is_alive, g1_par_keep_alive, g1_par_drain);
1967 }
1968 };
1969
1970 void G1CMRefProcTaskExecutor::execute(ProcessTask& proc_task) {
1971 assert(_workers != NULL, "Need parallel worker threads.");
1972 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
1973
1974 G1CMRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _cm);
1975
1976 // We need to reset the concurrency level before each
1977 // proxy task execution, so that the termination protocol
1978 // and overflow handling in CMTask::do_marking_step() knows
1979 // how many workers to wait for.
1980 _cm->set_concurrency(_active_workers);
1981 _workers->run_task(&proc_task_proxy);
1982 }
1983
1984 class G1CMRefEnqueueTaskProxy: public AbstractGangTask {
1985 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
1986 EnqueueTask& _enq_task;
1987
1988 public:
1989 G1CMRefEnqueueTaskProxy(EnqueueTask& enq_task) :
1990 AbstractGangTask("Enqueue reference objects in parallel"),
1991 _enq_task(enq_task) { }
1992
1993 virtual void work(uint worker_id) {
1994 _enq_task.work(worker_id);
1995 }
1996 };
1997
1998 void G1CMRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
1999 assert(_workers != NULL, "Need parallel worker threads.");
2000 assert(_g1h->ref_processor_cm()->processing_is_mt(), "processing is not MT");
2001
2002 G1CMRefEnqueueTaskProxy enq_task_proxy(enq_task);
2003
2004 // Not strictly necessary but...
2005 //
2006 // We need to reset the concurrency level before each
2007 // proxy task execution, so that the termination protocol
2008 // and overflow handling in CMTask::do_marking_step() knows
2009 // how many workers to wait for.
2010 _cm->set_concurrency(_active_workers);
2011 _workers->run_task(&enq_task_proxy);
2012 }
2013
2014 void ConcurrentMark::weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes) {
2015 G1CollectedHeap::heap()->parallel_cleaning(is_alive, true, true, purged_classes);
2016 }
2017
2018 void ConcurrentMark::weakRefsWork(bool clear_all_soft_refs) {
2019 if (has_overflown()) {
2020 // Skip processing the discovered references if we have
2021 // overflown the global marking stack. Reference objects
2022 // only get discovered once so it is OK to not
2023 // de-populate the discovered reference lists. We could have,
2024 // but the only benefit would be that, when marking restarts,
2025 // less reference objects are discovered.
2026 return;
2027 }
2028
2029 ResourceMark rm;
2030 HandleMark hm;
2031
2032 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2033
2034 // Is alive closure.
2035 G1CMIsAliveClosure g1_is_alive(g1h);
2036
2037 // Inner scope to exclude the cleaning of the string and symbol
2038 // tables from the displayed time.
2039 {
2040 GCTraceTime(Debug, gc) trace("GC Ref Proc", g1h->gc_timer_cm());
2041
2042 ReferenceProcessor* rp = g1h->ref_processor_cm();
2043
2044 // See the comment in G1CollectedHeap::ref_processing_init()
2045 // about how reference processing currently works in G1.
2046
2047 // Set the soft reference policy
2048 rp->setup_policy(clear_all_soft_refs);
2049 assert(_markStack.isEmpty(), "mark stack should be empty");
2050
2051 // Instances of the 'Keep Alive' and 'Complete GC' closures used
2052 // in serial reference processing. Note these closures are also
2053 // used for serially processing (by the the current thread) the
2054 // JNI references during parallel reference processing.
2055 //
2056 // These closures do not need to synchronize with the worker
2057 // threads involved in parallel reference processing as these
2058 // instances are executed serially by the current thread (e.g.
2059 // reference processing is not multi-threaded and is thus
2060 // performed by the current thread instead of a gang worker).
2061 //
2062 // The gang tasks involved in parallel reference processing create
2063 // their own instances of these closures, which do their own
2064 // synchronization among themselves.
2065 G1CMKeepAliveAndDrainClosure g1_keep_alive(this, task(0), true /* is_serial */);
2066 G1CMDrainMarkingStackClosure g1_drain_mark_stack(this, task(0), true /* is_serial */);
2067
2068 // We need at least one active thread. If reference processing
2069 // is not multi-threaded we use the current (VMThread) thread,
2070 // otherwise we use the work gang from the G1CollectedHeap and
2071 // we utilize all the worker threads we can.
2072 bool processing_is_mt = rp->processing_is_mt();
2073 uint active_workers = (processing_is_mt ? g1h->workers()->active_workers() : 1U);
2074 active_workers = MAX2(MIN2(active_workers, _max_worker_id), 1U);
2075
2076 // Parallel processing task executor.
2077 G1CMRefProcTaskExecutor par_task_executor(g1h, this,
2078 g1h->workers(), active_workers);
2079 AbstractRefProcTaskExecutor* executor = (processing_is_mt ? &par_task_executor : NULL);
2080
2081 // Set the concurrency level. The phase was already set prior to
2082 // executing the remark task.
2083 set_concurrency(active_workers);
2084
2085 // Set the degree of MT processing here. If the discovery was done MT,
2086 // the number of threads involved during discovery could differ from
2087 // the number of active workers. This is OK as long as the discovered
2088 // Reference lists are balanced (see balance_all_queues() and balance_queues()).
2089 rp->set_active_mt_degree(active_workers);
2090
2091 // Process the weak references.
2092 const ReferenceProcessorStats& stats =
2093 rp->process_discovered_references(&g1_is_alive,
2094 &g1_keep_alive,
2095 &g1_drain_mark_stack,
2096 executor,
2097 g1h->gc_timer_cm());
2098 g1h->gc_tracer_cm()->report_gc_reference_stats(stats);
2099
2100 // The do_oop work routines of the keep_alive and drain_marking_stack
2101 // oop closures will set the has_overflown flag if we overflow the
2102 // global marking stack.
2103
2104 assert(_markStack.overflow() || _markStack.isEmpty(),
2105 "mark stack should be empty (unless it overflowed)");
2106
2107 if (_markStack.overflow()) {
2108 // This should have been done already when we tried to push an
2109 // entry on to the global mark stack. But let's do it again.
2110 set_has_overflown();
2111 }
2112
2113 assert(rp->num_q() == active_workers, "why not");
2114
2115 rp->enqueue_discovered_references(executor);
2116
2117 rp->verify_no_references_recorded();
2118 assert(!rp->discovery_enabled(), "Post condition");
2119 }
2120
2121 if (has_overflown()) {
2122 // We can not trust g1_is_alive if the marking stack overflowed
2123 return;
2124 }
2125
2126 assert(_markStack.isEmpty(), "Marking should have completed");
2127
2128 // Unload Klasses, String, Symbols, Code Cache, etc.
2129 {
2130 GCTraceTime(Debug, gc) trace("Unloading", g1h->gc_timer_cm());
2131
2132 if (ClassUnloadingWithConcurrentMark) {
2133 bool purged_classes;
2134
2135 {
2136 GCTraceTime(Trace, gc) trace("System Dictionary Unloading", g1h->gc_timer_cm());
2137 purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
2138 }
2139
2140 {
2141 GCTraceTime(Trace, gc) trace("Parallel Unloading", g1h->gc_timer_cm());
2142 weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
2143 }
2144 }
2145
2146 if (G1StringDedup::is_enabled()) {
2147 GCTraceTime(Trace, gc) trace("String Deduplication Unlink", g1h->gc_timer_cm());
2148 G1StringDedup::unlink(&g1_is_alive);
2149 }
2150 }
2151 }
2152
2153 void ConcurrentMark::swapMarkBitMaps() {
2154 CMBitMapRO* temp = _prevMarkBitMap;
2155 _prevMarkBitMap = (CMBitMapRO*)_nextMarkBitMap;
2156 _nextMarkBitMap = (CMBitMap*) temp;
2157 }
2158
2159 // Closure for marking entries in SATB buffers.
2160 class CMSATBBufferClosure : public SATBBufferClosure {
2161 private:
2162 CMTask* _task;
2163 G1CollectedHeap* _g1h;
2164
2165 // This is very similar to CMTask::deal_with_reference, but with
2166 // more relaxed requirements for the argument, so this must be more
2167 // circumspect about treating the argument as an object.
2168 void do_entry(void* entry) const {
2169 _task->increment_refs_reached();
2170 HeapRegion* hr = _g1h->heap_region_containing(entry);
2171 if (entry < hr->next_top_at_mark_start()) {
2172 // Until we get here, we don't know whether entry refers to a valid
2173 // object; it could instead have been a stale reference.
2174 oop obj = static_cast<oop>(entry);
2175 assert(obj->is_oop(true /* ignore mark word */),
2176 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(obj));
2177 _task->make_reference_grey(obj, hr);
2178 }
2179 }
2180
2181 public:
2182 CMSATBBufferClosure(CMTask* task, G1CollectedHeap* g1h)
2183 : _task(task), _g1h(g1h) { }
2184
2185 virtual void do_buffer(void** buffer, size_t size) {
2186 for (size_t i = 0; i < size; ++i) {
2187 do_entry(buffer[i]);
2188 }
2189 }
2190 };
2191
2192 class G1RemarkThreadsClosure : public ThreadClosure {
2193 CMSATBBufferClosure _cm_satb_cl;
2194 G1CMOopClosure _cm_cl;
2195 MarkingCodeBlobClosure _code_cl;
2196 int _thread_parity;
2197
2198 public:
2199 G1RemarkThreadsClosure(G1CollectedHeap* g1h, CMTask* task) :
2200 _cm_satb_cl(task, g1h),
2201 _cm_cl(g1h, g1h->concurrent_mark(), task),
2202 _code_cl(&_cm_cl, !CodeBlobToOopClosure::FixRelocations),
2203 _thread_parity(Threads::thread_claim_parity()) {}
2204
2205 void do_thread(Thread* thread) {
2206 if (thread->is_Java_thread()) {
2207 if (thread->claim_oops_do(true, _thread_parity)) {
2208 JavaThread* jt = (JavaThread*)thread;
2209
2210 // In theory it should not be neccessary to explicitly walk the nmethods to find roots for concurrent marking
2211 // however the liveness of oops reachable from nmethods have very complex lifecycles:
2212 // * Alive if on the stack of an executing method
2213 // * Weakly reachable otherwise
2214 // Some objects reachable from nmethods, such as the class loader (or klass_holder) of the receiver should be
2215 // live by the SATB invariant but other oops recorded in nmethods may behave differently.
2216 jt->nmethods_do(&_code_cl);
2217
2218 jt->satb_mark_queue().apply_closure_and_empty(&_cm_satb_cl);
2219 }
2220 } else if (thread->is_VM_thread()) {
2221 if (thread->claim_oops_do(true, _thread_parity)) {
2222 JavaThread::satb_mark_queue_set().shared_satb_queue()->apply_closure_and_empty(&_cm_satb_cl);
2223 }
2224 }
2225 }
2226 };
2227
2228 class CMRemarkTask: public AbstractGangTask {
2229 private:
2230 ConcurrentMark* _cm;
2231 public:
2232 void work(uint worker_id) {
2233 // Since all available tasks are actually started, we should
2234 // only proceed if we're supposed to be active.
2235 if (worker_id < _cm->active_tasks()) {
2236 CMTask* task = _cm->task(worker_id);
2237 task->record_start_time();
2238 {
2239 ResourceMark rm;
2240 HandleMark hm;
2241
2242 G1RemarkThreadsClosure threads_f(G1CollectedHeap::heap(), task);
2243 Threads::threads_do(&threads_f);
2244 }
2245
2246 do {
2247 task->do_marking_step(1000000000.0 /* something very large */,
2248 true /* do_termination */,
2249 false /* is_serial */);
2250 } while (task->has_aborted() && !_cm->has_overflown());
2251 // If we overflow, then we do not want to restart. We instead
2252 // want to abort remark and do concurrent marking again.
2253 task->record_end_time();
2254 }
2255 }
2256
2257 CMRemarkTask(ConcurrentMark* cm, uint active_workers) :
2258 AbstractGangTask("Par Remark"), _cm(cm) {
2259 _cm->terminator()->reset_for_reuse(active_workers);
2260 }
2261 };
2262
2263 void ConcurrentMark::checkpointRootsFinalWork() {
2264 ResourceMark rm;
2265 HandleMark hm;
2266 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2267
2268 GCTraceTime(Debug, gc) trace("Finalize Marking", g1h->gc_timer_cm());
2269
2270 g1h->ensure_parsability(false);
2271
2272 // this is remark, so we'll use up all active threads
2273 uint active_workers = g1h->workers()->active_workers();
2274 set_concurrency_and_phase(active_workers, false /* concurrent */);
2275 // Leave _parallel_marking_threads at it's
2276 // value originally calculated in the ConcurrentMark
2277 // constructor and pass values of the active workers
2278 // through the gang in the task.
2279
2280 {
2281 StrongRootsScope srs(active_workers);
2282
2283 CMRemarkTask remarkTask(this, active_workers);
2284 // We will start all available threads, even if we decide that the
2285 // active_workers will be fewer. The extra ones will just bail out
2286 // immediately.
2287 g1h->workers()->run_task(&remarkTask);
2288 }
2289
2290 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2291 guarantee(has_overflown() ||
2292 satb_mq_set.completed_buffers_num() == 0,
2293 "Invariant: has_overflown = %s, num buffers = %d",
2294 BOOL_TO_STR(has_overflown()),
2295 satb_mq_set.completed_buffers_num());
2296
2297 print_stats();
2298 }
2299
2300 void ConcurrentMark::clearRangePrevBitmap(MemRegion mr) {
2301 // Note we are overriding the read-only view of the prev map here, via
2302 // the cast.
2303 ((CMBitMap*)_prevMarkBitMap)->clearRange(mr);
2304 }
2305
2306 HeapRegion*
2307 ConcurrentMark::claim_region(uint worker_id) {
2308 // "checkpoint" the finger
2309 HeapWord* finger = _finger;
2310
2311 // _heap_end will not change underneath our feet; it only changes at
2312 // yield points.
2313 while (finger < _heap_end) {
2314 assert(_g1h->is_in_g1_reserved(finger), "invariant");
2315
2316 HeapRegion* curr_region = _g1h->heap_region_containing(finger);
2317
2318 // Above heap_region_containing may return NULL as we always scan claim
2319 // until the end of the heap. In this case, just jump to the next region.
2320 HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
2321
2322 // Is the gap between reading the finger and doing the CAS too long?
2323 HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
2324 if (res == finger && curr_region != NULL) {
2325 // we succeeded
2326 HeapWord* bottom = curr_region->bottom();
2327 HeapWord* limit = curr_region->next_top_at_mark_start();
2328
2329 // notice that _finger == end cannot be guaranteed here since,
2330 // someone else might have moved the finger even further
2331 assert(_finger >= end, "the finger should have moved forward");
2332
2333 if (limit > bottom) {
2334 return curr_region;
2335 } else {
2336 assert(limit == bottom,
2337 "the region limit should be at bottom");
2338 // we return NULL and the caller should try calling
2339 // claim_region() again.
2340 return NULL;
2341 }
2342 } else {
2343 assert(_finger > finger, "the finger should have moved forward");
2344 // read it again
2345 finger = _finger;
2346 }
2347 }
2348
2349 return NULL;
2350 }
2351
2352 #ifndef PRODUCT
2353 class VerifyNoCSetOops VALUE_OBJ_CLASS_SPEC {
2354 private:
2355 G1CollectedHeap* _g1h;
2356 const char* _phase;
2357 int _info;
2358
2359 public:
2360 VerifyNoCSetOops(const char* phase, int info = -1) :
2361 _g1h(G1CollectedHeap::heap()),
2362 _phase(phase),
2363 _info(info)
2364 { }
2365
2366 void operator()(oop obj) const {
2367 guarantee(obj->is_oop(),
2368 "Non-oop " PTR_FORMAT ", phase: %s, info: %d",
2369 p2i(obj), _phase, _info);
2370 guarantee(!_g1h->obj_in_cs(obj),
2371 "obj: " PTR_FORMAT " in CSet, phase: %s, info: %d",
2372 p2i(obj), _phase, _info);
2373 }
2374 };
2375
2376 void ConcurrentMark::verify_no_cset_oops() {
2377 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
2378 if (!G1CollectedHeap::heap()->collector_state()->mark_in_progress()) {
2379 return;
2380 }
2381
2382 // Verify entries on the global mark stack
2383 _markStack.iterate(VerifyNoCSetOops("Stack"));
2384
2385 // Verify entries on the task queues
2386 for (uint i = 0; i < _max_worker_id; ++i) {
2387 CMTaskQueue* queue = _task_queues->queue(i);
2388 queue->iterate(VerifyNoCSetOops("Queue", i));
2389 }
2390
2391 // Verify the global finger
2392 HeapWord* global_finger = finger();
2393 if (global_finger != NULL && global_finger < _heap_end) {
2394 // Since we always iterate over all regions, we might get a NULL HeapRegion
2395 // here.
2396 HeapRegion* global_hr = _g1h->heap_region_containing(global_finger);
2397 guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
2398 "global finger: " PTR_FORMAT " region: " HR_FORMAT,
2399 p2i(global_finger), HR_FORMAT_PARAMS(global_hr));
2400 }
2401
2402 // Verify the task fingers
2403 assert(parallel_marking_threads() <= _max_worker_id, "sanity");
2404 for (uint i = 0; i < parallel_marking_threads(); ++i) {
2405 CMTask* task = _tasks[i];
2406 HeapWord* task_finger = task->finger();
2407 if (task_finger != NULL && task_finger < _heap_end) {
2408 // See above note on the global finger verification.
2409 HeapRegion* task_hr = _g1h->heap_region_containing(task_finger);
2410 guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
2411 !task_hr->in_collection_set(),
2412 "task finger: " PTR_FORMAT " region: " HR_FORMAT,
2413 p2i(task_finger), HR_FORMAT_PARAMS(task_hr));
2414 }
2415 }
2416 }
2417 #endif // PRODUCT
2418
2419 // Aggregate the counting data that was constructed concurrently
2420 // with marking.
2421 class AggregateCountDataHRClosure: public HeapRegionClosure {
2422 G1CollectedHeap* _g1h;
2423 ConcurrentMark* _cm;
2424 CardTableModRefBS* _ct_bs;
2425 BitMap* _cm_card_bm;
2426 uint _max_worker_id;
2427
2428 public:
2429 AggregateCountDataHRClosure(G1CollectedHeap* g1h,
2430 BitMap* cm_card_bm,
2431 uint max_worker_id) :
2432 _g1h(g1h), _cm(g1h->concurrent_mark()),
2433 _ct_bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())),
2434 _cm_card_bm(cm_card_bm), _max_worker_id(max_worker_id) { }
2435
2436 bool doHeapRegion(HeapRegion* hr) {
2437 HeapWord* start = hr->bottom();
2438 HeapWord* limit = hr->next_top_at_mark_start();
2439 HeapWord* end = hr->end();
2440
2441 assert(start <= limit && limit <= hr->top() && hr->top() <= hr->end(),
2442 "Preconditions not met - "
2443 "start: " PTR_FORMAT ", limit: " PTR_FORMAT ", "
2444 "top: " PTR_FORMAT ", end: " PTR_FORMAT,
2445 p2i(start), p2i(limit), p2i(hr->top()), p2i(hr->end()));
2446
2447 assert(hr->next_marked_bytes() == 0, "Precondition");
2448
2449 if (start == limit) {
2450 // NTAMS of this region has not been set so nothing to do.
2451 return false;
2452 }
2453
2454 // 'start' should be in the heap.
2455 assert(_g1h->is_in_g1_reserved(start) && _ct_bs->is_card_aligned(start), "sanity");
2456 // 'end' *may* be just beyond the end of the heap (if hr is the last region)
2457 assert(!_g1h->is_in_g1_reserved(end) || _ct_bs->is_card_aligned(end), "sanity");
2458
2459 BitMap::idx_t start_idx = _cm->card_bitmap_index_for(start);
2460 BitMap::idx_t limit_idx = _cm->card_bitmap_index_for(limit);
2461 BitMap::idx_t end_idx = _cm->card_bitmap_index_for(end);
2462
2463 // If ntams is not card aligned then we bump card bitmap index
2464 // for limit so that we get the all the cards spanned by
2465 // the object ending at ntams.
2466 // Note: if this is the last region in the heap then ntams
2467 // could be actually just beyond the end of the the heap;
2468 // limit_idx will then correspond to a (non-existent) card
2469 // that is also outside the heap.
2470 if (_g1h->is_in_g1_reserved(limit) && !_ct_bs->is_card_aligned(limit)) {
2471 limit_idx += 1;
2472 }
2473
2474 assert(limit_idx <= end_idx, "or else use atomics");
2475
2476 // Aggregate the "stripe" in the count data associated with hr.
2477 uint hrm_index = hr->hrm_index();
2478 size_t marked_bytes = 0;
2479
2480 for (uint i = 0; i < _max_worker_id; i += 1) {
2481 size_t* marked_bytes_array = _cm->count_marked_bytes_array_for(i);
2482 BitMap* task_card_bm = _cm->count_card_bitmap_for(i);
2483
2484 // Fetch the marked_bytes in this region for task i and
2485 // add it to the running total for this region.
2486 marked_bytes += marked_bytes_array[hrm_index];
2487
2488 // Now union the bitmaps[0,max_worker_id)[start_idx..limit_idx)
2489 // into the global card bitmap.
2490 BitMap::idx_t scan_idx = task_card_bm->get_next_one_offset(start_idx, limit_idx);
2491
2492 while (scan_idx < limit_idx) {
2493 assert(task_card_bm->at(scan_idx) == true, "should be");
2494 _cm_card_bm->set_bit(scan_idx);
2495 assert(_cm_card_bm->at(scan_idx) == true, "should be");
2496
2497 // BitMap::get_next_one_offset() can handle the case when
2498 // its left_offset parameter is greater than its right_offset
2499 // parameter. It does, however, have an early exit if
2500 // left_offset == right_offset. So let's limit the value
2501 // passed in for left offset here.
2502 BitMap::idx_t next_idx = MIN2(scan_idx + 1, limit_idx);
2503 scan_idx = task_card_bm->get_next_one_offset(next_idx, limit_idx);
2504 }
2505 }
2506
2507 // Update the marked bytes for this region.
2508 hr->add_to_marked_bytes(marked_bytes);
2509
2510 // Next heap region
2511 return false;
2512 }
2513 };
2514
2515 class G1AggregateCountDataTask: public AbstractGangTask {
2516 protected:
2517 G1CollectedHeap* _g1h;
2518 ConcurrentMark* _cm;
2519 BitMap* _cm_card_bm;
2520 uint _max_worker_id;
2521 uint _active_workers;
2522 HeapRegionClaimer _hrclaimer;
2523
2524 public:
2525 G1AggregateCountDataTask(G1CollectedHeap* g1h,
2526 ConcurrentMark* cm,
2527 BitMap* cm_card_bm,
2528 uint max_worker_id,
2529 uint n_workers) :
2530 AbstractGangTask("Count Aggregation"),
2531 _g1h(g1h), _cm(cm), _cm_card_bm(cm_card_bm),
2532 _max_worker_id(max_worker_id),
2533 _active_workers(n_workers),
2534 _hrclaimer(_active_workers) {
2535 }
2536
2537 void work(uint worker_id) {
2538 AggregateCountDataHRClosure cl(_g1h, _cm_card_bm, _max_worker_id);
2539
2540 _g1h->heap_region_par_iterate(&cl, worker_id, &_hrclaimer);
2541 }
2542 };
2543
2544
2545 void ConcurrentMark::aggregate_count_data() {
2546 uint n_workers = _g1h->workers()->active_workers();
2547
2548 G1AggregateCountDataTask g1_par_agg_task(_g1h, this, &_card_bm,
2549 _max_worker_id, n_workers);
2550
2551 _g1h->workers()->run_task(&g1_par_agg_task);
2552 }
2553
2554 // Clear the per-worker arrays used to store the per-region counting data
2555 void ConcurrentMark::clear_all_count_data() {
2556 // Clear the global card bitmap - it will be filled during
2557 // liveness count aggregation (during remark) and the
2558 // final counting task.
2559 _card_bm.clear();
2560
2561 // Clear the global region bitmap - it will be filled as part
2562 // of the final counting task.
2563 _region_bm.clear();
2564
2565 uint max_regions = _g1h->max_regions();
2566 assert(_max_worker_id > 0, "uninitialized");
2567
2568 for (uint i = 0; i < _max_worker_id; i += 1) {
2569 BitMap* task_card_bm = count_card_bitmap_for(i);
2570 size_t* marked_bytes_array = count_marked_bytes_array_for(i);
2571
2572 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
2573 assert(marked_bytes_array != NULL, "uninitialized");
2574
2575 memset(marked_bytes_array, 0, (size_t) max_regions * sizeof(size_t));
2576 task_card_bm->clear();
2577 }
2578 }
2579
2580 void ConcurrentMark::print_stats() {
2581 if (!log_is_enabled(Debug, gc, stats)) {
2582 return;
2583 }
2584 log_debug(gc, stats)("---------------------------------------------------------------------");
2585 for (size_t i = 0; i < _active_tasks; ++i) {
2586 _tasks[i]->print_stats();
2587 log_debug(gc, stats)("---------------------------------------------------------------------");
2588 }
2589 }
2590
2591 // abandon current marking iteration due to a Full GC
2592 void ConcurrentMark::abort() {
2593 if (!cmThread()->during_cycle() || _has_aborted) {
2594 // We haven't started a concurrent cycle or we have already aborted it. No need to do anything.
2595 return;
2596 }
2597
2598 // Clear all marks in the next bitmap for the next marking cycle. This will allow us to skip the next
2599 // concurrent bitmap clearing.
2600 _nextMarkBitMap->clearAll();
2601
2602 // Note we cannot clear the previous marking bitmap here
2603 // since VerifyDuringGC verifies the objects marked during
2604 // a full GC against the previous bitmap.
2605
2606 // Clear the liveness counting data
2607 clear_all_count_data();
2608 // Empty mark stack
2609 reset_marking_state();
2610 for (uint i = 0; i < _max_worker_id; ++i) {
2611 _tasks[i]->clear_region_fields();
2612 }
2613 _first_overflow_barrier_sync.abort();
2614 _second_overflow_barrier_sync.abort();
2615 _has_aborted = true;
2616
2617 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2618 satb_mq_set.abandon_partial_marking();
2619 // This can be called either during or outside marking, we'll read
2620 // the expected_active value from the SATB queue set.
2621 satb_mq_set.set_active_all_threads(
2622 false, /* new active value */
2623 satb_mq_set.is_active() /* expected_active */);
2624
2625 _g1h->trace_heap_after_concurrent_cycle();
2626
2627 // Close any open concurrent phase timing
2628 register_concurrent_phase_end();
2629
2630 _g1h->register_concurrent_cycle_end();
2631 }
2632
2633 static void print_ms_time_info(const char* prefix, const char* name,
2634 NumberSeq& ns) {
2635 log_trace(gc, marking)("%s%5d %12s: total time = %8.2f s (avg = %8.2f ms).",
2636 prefix, ns.num(), name, ns.sum()/1000.0, ns.avg());
2637 if (ns.num() > 0) {
2638 log_trace(gc, marking)("%s [std. dev = %8.2f ms, max = %8.2f ms]",
2639 prefix, ns.sd(), ns.maximum());
2640 }
2641 }
2642
2643 void ConcurrentMark::print_summary_info() {
2644 LogHandle(gc, marking) log;
2645 if (!log.is_trace()) {
2646 return;
2647 }
2648
2649 log.trace(" Concurrent marking:");
2650 print_ms_time_info(" ", "init marks", _init_times);
2651 print_ms_time_info(" ", "remarks", _remark_times);
2652 {
2653 print_ms_time_info(" ", "final marks", _remark_mark_times);
2654 print_ms_time_info(" ", "weak refs", _remark_weak_ref_times);
2655
2656 }
2657 print_ms_time_info(" ", "cleanups", _cleanup_times);
2658 log.trace(" Final counting total time = %8.2f s (avg = %8.2f ms).",
2659 _total_counting_time, (_cleanup_times.num() > 0 ? _total_counting_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2660 if (G1ScrubRemSets) {
2661 log.trace(" RS scrub total time = %8.2f s (avg = %8.2f ms).",
2662 _total_rs_scrub_time, (_cleanup_times.num() > 0 ? _total_rs_scrub_time * 1000.0 / (double)_cleanup_times.num() : 0.0));
2663 }
2664 log.trace(" Total stop_world time = %8.2f s.",
2665 (_init_times.sum() + _remark_times.sum() + _cleanup_times.sum())/1000.0);
2666 log.trace(" Total concurrent time = %8.2f s (%8.2f s marking).",
2667 cmThread()->vtime_accum(), cmThread()->vtime_mark_accum());
2668 }
2669
2670 void ConcurrentMark::print_worker_threads_on(outputStream* st) const {
2671 _parallel_workers->print_worker_threads_on(st);
2672 }
2673
2674 void ConcurrentMark::print_on_error(outputStream* st) const {
2675 st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
2676 p2i(_prevMarkBitMap), p2i(_nextMarkBitMap));
2677 _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
2678 _nextMarkBitMap->print_on_error(st, " Next Bits: ");
2679 }
2680
2681 // We take a break if someone is trying to stop the world.
2682 bool ConcurrentMark::do_yield_check(uint worker_id) {
2683 if (SuspendibleThreadSet::should_yield()) {
2684 if (worker_id == 0) {
2685 _g1h->g1_policy()->record_concurrent_pause();
2686 }
2687 SuspendibleThreadSet::yield();
2688 return true;
2689 } else {
2690 return false;
2691 }
2692 }
2693
2694 // Closure for iteration over bitmaps
2695 class CMBitMapClosure : public BitMapClosure {
2696 private:
2697 // the bitmap that is being iterated over
2698 CMBitMap* _nextMarkBitMap;
2699 ConcurrentMark* _cm;
2700 CMTask* _task;
2701
2702 public:
2703 CMBitMapClosure(CMTask *task, ConcurrentMark* cm, CMBitMap* nextMarkBitMap) :
2704 _task(task), _cm(cm), _nextMarkBitMap(nextMarkBitMap) { }
2705
2706 bool do_bit(size_t offset) {
2707 HeapWord* addr = _nextMarkBitMap->offsetToHeapWord(offset);
2708 assert(_nextMarkBitMap->isMarked(addr), "invariant");
2709 assert( addr < _cm->finger(), "invariant");
2710 assert(addr >= _task->finger(), "invariant");
2711
2712 // We move that task's local finger along.
2713 _task->move_finger_to(addr);
2714
2715 _task->scan_object(oop(addr));
2716 // we only partially drain the local queue and global stack
2717 _task->drain_local_queue(true);
2718 _task->drain_global_stack(true);
2719
2720 // if the has_aborted flag has been raised, we need to bail out of
2721 // the iteration
2722 return !_task->has_aborted();
2723 }
2724 };
2725
2726 static ReferenceProcessor* get_cm_oop_closure_ref_processor(G1CollectedHeap* g1h) {
2727 ReferenceProcessor* result = NULL;
2728 if (G1UseConcMarkReferenceProcessing) {
2729 result = g1h->ref_processor_cm();
2730 assert(result != NULL, "should not be NULL");
2731 }
2732 return result;
2733 }
2734
2735 G1CMOopClosure::G1CMOopClosure(G1CollectedHeap* g1h,
2736 ConcurrentMark* cm,
2737 CMTask* task)
2738 : MetadataAwareOopClosure(get_cm_oop_closure_ref_processor(g1h)),
2739 _g1h(g1h), _cm(cm), _task(task)
2740 { }
2741
2742 void CMTask::setup_for_region(HeapRegion* hr) {
2743 assert(hr != NULL,
2744 "claim_region() should have filtered out NULL regions");
2745 _curr_region = hr;
2746 _finger = hr->bottom();
2747 update_region_limit();
2748 }
2749
2750 void CMTask::update_region_limit() {
2751 HeapRegion* hr = _curr_region;
2752 HeapWord* bottom = hr->bottom();
2753 HeapWord* limit = hr->next_top_at_mark_start();
2754
2755 if (limit == bottom) {
2756 // The region was collected underneath our feet.
2757 // We set the finger to bottom to ensure that the bitmap
2758 // iteration that will follow this will not do anything.
2759 // (this is not a condition that holds when we set the region up,
2760 // as the region is not supposed to be empty in the first place)
2761 _finger = bottom;
2762 } else if (limit >= _region_limit) {
2763 assert(limit >= _finger, "peace of mind");
2764 } else {
2765 assert(limit < _region_limit, "only way to get here");
2766 // This can happen under some pretty unusual circumstances. An
2767 // evacuation pause empties the region underneath our feet (NTAMS
2768 // at bottom). We then do some allocation in the region (NTAMS
2769 // stays at bottom), followed by the region being used as a GC
2770 // alloc region (NTAMS will move to top() and the objects
2771 // originally below it will be grayed). All objects now marked in
2772 // the region are explicitly grayed, if below the global finger,
2773 // and we do not need in fact to scan anything else. So, we simply
2774 // set _finger to be limit to ensure that the bitmap iteration
2775 // doesn't do anything.
2776 _finger = limit;
2777 }
2778
2779 _region_limit = limit;
2780 }
2781
2782 void CMTask::giveup_current_region() {
2783 assert(_curr_region != NULL, "invariant");
2784 clear_region_fields();
2785 }
2786
2787 void CMTask::clear_region_fields() {
2788 // Values for these three fields that indicate that we're not
2789 // holding on to a region.
2790 _curr_region = NULL;
2791 _finger = NULL;
2792 _region_limit = NULL;
2793 }
2794
2795 void CMTask::set_cm_oop_closure(G1CMOopClosure* cm_oop_closure) {
2796 if (cm_oop_closure == NULL) {
2797 assert(_cm_oop_closure != NULL, "invariant");
2798 } else {
2799 assert(_cm_oop_closure == NULL, "invariant");
2800 }
2801 _cm_oop_closure = cm_oop_closure;
2802 }
2803
2804 void CMTask::reset(CMBitMap* nextMarkBitMap) {
2805 guarantee(nextMarkBitMap != NULL, "invariant");
2806 _nextMarkBitMap = nextMarkBitMap;
2807 clear_region_fields();
2808
2809 _calls = 0;
2810 _elapsed_time_ms = 0.0;
2811 _termination_time_ms = 0.0;
2812 _termination_start_time_ms = 0.0;
2813 }
2814
2815 bool CMTask::should_exit_termination() {
2816 regular_clock_call();
2817 // This is called when we are in the termination protocol. We should
2818 // quit if, for some reason, this task wants to abort or the global
2819 // stack is not empty (this means that we can get work from it).
2820 return !_cm->mark_stack_empty() || has_aborted();
2821 }
2822
2823 void CMTask::reached_limit() {
2824 assert(_words_scanned >= _words_scanned_limit ||
2825 _refs_reached >= _refs_reached_limit ,
2826 "shouldn't have been called otherwise");
2827 regular_clock_call();
2828 }
2829
2830 void CMTask::regular_clock_call() {
2831 if (has_aborted()) return;
2832
2833 // First, we need to recalculate the words scanned and refs reached
2834 // limits for the next clock call.
2835 recalculate_limits();
2836
2837 // During the regular clock call we do the following
2838
2839 // (1) If an overflow has been flagged, then we abort.
2840 if (_cm->has_overflown()) {
2841 set_has_aborted();
2842 return;
2843 }
2844
2845 // If we are not concurrent (i.e. we're doing remark) we don't need
2846 // to check anything else. The other steps are only needed during
2847 // the concurrent marking phase.
2848 if (!concurrent()) return;
2849
2850 // (2) If marking has been aborted for Full GC, then we also abort.
2851 if (_cm->has_aborted()) {
2852 set_has_aborted();
2853 return;
2854 }
2855
2856 double curr_time_ms = os::elapsedVTime() * 1000.0;
2857
2858 // (4) We check whether we should yield. If we have to, then we abort.
2859 if (SuspendibleThreadSet::should_yield()) {
2860 // We should yield. To do this we abort the task. The caller is
2861 // responsible for yielding.
2862 set_has_aborted();
2863 return;
2864 }
2865
2866 // (5) We check whether we've reached our time quota. If we have,
2867 // then we abort.
2868 double elapsed_time_ms = curr_time_ms - _start_time_ms;
2869 if (elapsed_time_ms > _time_target_ms) {
2870 set_has_aborted();
2871 _has_timed_out = true;
2872 return;
2873 }
2874
2875 // (6) Finally, we check whether there are enough completed STAB
2876 // buffers available for processing. If there are, we abort.
2877 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
2878 if (!_draining_satb_buffers && satb_mq_set.process_completed_buffers()) {
2879 // we do need to process SATB buffers, we'll abort and restart
2880 // the marking task to do so
2881 set_has_aborted();
2882 return;
2883 }
2884 }
2885
2886 void CMTask::recalculate_limits() {
2887 _real_words_scanned_limit = _words_scanned + words_scanned_period;
2888 _words_scanned_limit = _real_words_scanned_limit;
2889
2890 _real_refs_reached_limit = _refs_reached + refs_reached_period;
2891 _refs_reached_limit = _real_refs_reached_limit;
2892 }
2893
2894 void CMTask::decrease_limits() {
2895 // This is called when we believe that we're going to do an infrequent
2896 // operation which will increase the per byte scanned cost (i.e. move
2897 // entries to/from the global stack). It basically tries to decrease the
2898 // scanning limit so that the clock is called earlier.
2899
2900 _words_scanned_limit = _real_words_scanned_limit -
2901 3 * words_scanned_period / 4;
2902 _refs_reached_limit = _real_refs_reached_limit -
2903 3 * refs_reached_period / 4;
2904 }
2905
2906 void CMTask::move_entries_to_global_stack() {
2907 // local array where we'll store the entries that will be popped
2908 // from the local queue
2909 oop buffer[global_stack_transfer_size];
2910
2911 int n = 0;
2912 oop obj;
2913 while (n < global_stack_transfer_size && _task_queue->pop_local(obj)) {
2914 buffer[n] = obj;
2915 ++n;
2916 }
2917
2918 if (n > 0) {
2919 // we popped at least one entry from the local queue
2920
2921 if (!_cm->mark_stack_push(buffer, n)) {
2922 set_has_aborted();
2923 }
2924 }
2925
2926 // this operation was quite expensive, so decrease the limits
2927 decrease_limits();
2928 }
2929
2930 void CMTask::get_entries_from_global_stack() {
2931 // local array where we'll store the entries that will be popped
2932 // from the global stack.
2933 oop buffer[global_stack_transfer_size];
2934 int n;
2935 _cm->mark_stack_pop(buffer, global_stack_transfer_size, &n);
2936 assert(n <= global_stack_transfer_size,
2937 "we should not pop more than the given limit");
2938 if (n > 0) {
2939 // yes, we did actually pop at least one entry
2940 for (int i = 0; i < n; ++i) {
2941 bool success = _task_queue->push(buffer[i]);
2942 // We only call this when the local queue is empty or under a
2943 // given target limit. So, we do not expect this push to fail.
2944 assert(success, "invariant");
2945 }
2946 }
2947
2948 // this operation was quite expensive, so decrease the limits
2949 decrease_limits();
2950 }
2951
2952 void CMTask::drain_local_queue(bool partially) {
2953 if (has_aborted()) return;
2954
2955 // Decide what the target size is, depending whether we're going to
2956 // drain it partially (so that other tasks can steal if they run out
2957 // of things to do) or totally (at the very end).
2958 size_t target_size;
2959 if (partially) {
2960 target_size = MIN2((size_t)_task_queue->max_elems()/3, GCDrainStackTargetSize);
2961 } else {
2962 target_size = 0;
2963 }
2964
2965 if (_task_queue->size() > target_size) {
2966 oop obj;
2967 bool ret = _task_queue->pop_local(obj);
2968 while (ret) {
2969 assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
2970 assert(!_g1h->is_on_master_free_list(
2971 _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
2972
2973 scan_object(obj);
2974
2975 if (_task_queue->size() <= target_size || has_aborted()) {
2976 ret = false;
2977 } else {
2978 ret = _task_queue->pop_local(obj);
2979 }
2980 }
2981 }
2982 }
2983
2984 void CMTask::drain_global_stack(bool partially) {
2985 if (has_aborted()) return;
2986
2987 // We have a policy to drain the local queue before we attempt to
2988 // drain the global stack.
2989 assert(partially || _task_queue->size() == 0, "invariant");
2990
2991 // Decide what the target size is, depending whether we're going to
2992 // drain it partially (so that other tasks can steal if they run out
2993 // of things to do) or totally (at the very end). Notice that,
2994 // because we move entries from the global stack in chunks or
2995 // because another task might be doing the same, we might in fact
2996 // drop below the target. But, this is not a problem.
2997 size_t target_size;
2998 if (partially) {
2999 target_size = _cm->partial_mark_stack_size_target();
3000 } else {
3001 target_size = 0;
3002 }
3003
3004 if (_cm->mark_stack_size() > target_size) {
3005 while (!has_aborted() && _cm->mark_stack_size() > target_size) {
3006 get_entries_from_global_stack();
3007 drain_local_queue(partially);
3008 }
3009 }
3010 }
3011
3012 // SATB Queue has several assumptions on whether to call the par or
3013 // non-par versions of the methods. this is why some of the code is
3014 // replicated. We should really get rid of the single-threaded version
3015 // of the code to simplify things.
3016 void CMTask::drain_satb_buffers() {
3017 if (has_aborted()) return;
3018
3019 // We set this so that the regular clock knows that we're in the
3020 // middle of draining buffers and doesn't set the abort flag when it
3021 // notices that SATB buffers are available for draining. It'd be
3022 // very counter productive if it did that. :-)
3023 _draining_satb_buffers = true;
3024
3025 CMSATBBufferClosure satb_cl(this, _g1h);
3026 SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
3027
3028 // This keeps claiming and applying the closure to completed buffers
3029 // until we run out of buffers or we need to abort.
3030 while (!has_aborted() &&
3031 satb_mq_set.apply_closure_to_completed_buffer(&satb_cl)) {
3032 regular_clock_call();
3033 }
3034
3035 _draining_satb_buffers = false;
3036
3037 assert(has_aborted() ||
3038 concurrent() ||
3039 satb_mq_set.completed_buffers_num() == 0, "invariant");
3040
3041 // again, this was a potentially expensive operation, decrease the
3042 // limits to get the regular clock call early
3043 decrease_limits();
3044 }
3045
3046 void CMTask::print_stats() {
3047 log_debug(gc, stats)("Marking Stats, task = %u, calls = %d",
3048 _worker_id, _calls);
3049 log_debug(gc, stats)(" Elapsed time = %1.2lfms, Termination time = %1.2lfms",
3050 _elapsed_time_ms, _termination_time_ms);
3051 log_debug(gc, stats)(" Step Times (cum): num = %d, avg = %1.2lfms, sd = %1.2lfms",
3052 _step_times_ms.num(), _step_times_ms.avg(),
3053 _step_times_ms.sd());
3054 log_debug(gc, stats)(" max = %1.2lfms, total = %1.2lfms",
3055 _step_times_ms.maximum(), _step_times_ms.sum());
3056 }
3057
3058 bool ConcurrentMark::try_stealing(uint worker_id, int* hash_seed, oop& obj) {
3059 return _task_queues->steal(worker_id, hash_seed, obj);
3060 }
3061
3062 /*****************************************************************************
3063
3064 The do_marking_step(time_target_ms, ...) method is the building
3065 block of the parallel marking framework. It can be called in parallel
3066 with other invocations of do_marking_step() on different tasks
3067 (but only one per task, obviously) and concurrently with the
3068 mutator threads, or during remark, hence it eliminates the need
3069 for two versions of the code. When called during remark, it will
3070 pick up from where the task left off during the concurrent marking
3071 phase. Interestingly, tasks are also claimable during evacuation
3072 pauses too, since do_marking_step() ensures that it aborts before
3073 it needs to yield.
3074
3075 The data structures that it uses to do marking work are the
3076 following:
3077
3078 (1) Marking Bitmap. If there are gray objects that appear only
3079 on the bitmap (this happens either when dealing with an overflow
3080 or when the initial marking phase has simply marked the roots
3081 and didn't push them on the stack), then tasks claim heap
3082 regions whose bitmap they then scan to find gray objects. A
3083 global finger indicates where the end of the last claimed region
3084 is. A local finger indicates how far into the region a task has
3085 scanned. The two fingers are used to determine how to gray an
3086 object (i.e. whether simply marking it is OK, as it will be
3087 visited by a task in the future, or whether it needs to be also
3088 pushed on a stack).
3089
3090 (2) Local Queue. The local queue of the task which is accessed
3091 reasonably efficiently by the task. Other tasks can steal from
3092 it when they run out of work. Throughout the marking phase, a
3093 task attempts to keep its local queue short but not totally
3094 empty, so that entries are available for stealing by other
3095 tasks. Only when there is no more work, a task will totally
3096 drain its local queue.
3097
3098 (3) Global Mark Stack. This handles local queue overflow. During
3099 marking only sets of entries are moved between it and the local
3100 queues, as access to it requires a mutex and more fine-grain
3101 interaction with it which might cause contention. If it
3102 overflows, then the marking phase should restart and iterate
3103 over the bitmap to identify gray objects. Throughout the marking
3104 phase, tasks attempt to keep the global mark stack at a small
3105 length but not totally empty, so that entries are available for
3106 popping by other tasks. Only when there is no more work, tasks
3107 will totally drain the global mark stack.
3108
3109 (4) SATB Buffer Queue. This is where completed SATB buffers are
3110 made available. Buffers are regularly removed from this queue
3111 and scanned for roots, so that the queue doesn't get too
3112 long. During remark, all completed buffers are processed, as
3113 well as the filled in parts of any uncompleted buffers.
3114
3115 The do_marking_step() method tries to abort when the time target
3116 has been reached. There are a few other cases when the
3117 do_marking_step() method also aborts:
3118
3119 (1) When the marking phase has been aborted (after a Full GC).
3120
3121 (2) When a global overflow (on the global stack) has been
3122 triggered. Before the task aborts, it will actually sync up with
3123 the other tasks to ensure that all the marking data structures
3124 (local queues, stacks, fingers etc.) are re-initialized so that
3125 when do_marking_step() completes, the marking phase can
3126 immediately restart.
3127
3128 (3) When enough completed SATB buffers are available. The
3129 do_marking_step() method only tries to drain SATB buffers right
3130 at the beginning. So, if enough buffers are available, the
3131 marking step aborts and the SATB buffers are processed at
3132 the beginning of the next invocation.
3133
3134 (4) To yield. when we have to yield then we abort and yield
3135 right at the end of do_marking_step(). This saves us from a lot
3136 of hassle as, by yielding we might allow a Full GC. If this
3137 happens then objects will be compacted underneath our feet, the
3138 heap might shrink, etc. We save checking for this by just
3139 aborting and doing the yield right at the end.
3140
3141 From the above it follows that the do_marking_step() method should
3142 be called in a loop (or, otherwise, regularly) until it completes.
3143
3144 If a marking step completes without its has_aborted() flag being
3145 true, it means it has completed the current marking phase (and
3146 also all other marking tasks have done so and have all synced up).
3147
3148 A method called regular_clock_call() is invoked "regularly" (in
3149 sub ms intervals) throughout marking. It is this clock method that
3150 checks all the abort conditions which were mentioned above and
3151 decides when the task should abort. A work-based scheme is used to
3152 trigger this clock method: when the number of object words the
3153 marking phase has scanned or the number of references the marking
3154 phase has visited reach a given limit. Additional invocations to
3155 the method clock have been planted in a few other strategic places
3156 too. The initial reason for the clock method was to avoid calling
3157 vtime too regularly, as it is quite expensive. So, once it was in
3158 place, it was natural to piggy-back all the other conditions on it
3159 too and not constantly check them throughout the code.
3160
3161 If do_termination is true then do_marking_step will enter its
3162 termination protocol.
3163
3164 The value of is_serial must be true when do_marking_step is being
3165 called serially (i.e. by the VMThread) and do_marking_step should
3166 skip any synchronization in the termination and overflow code.
3167 Examples include the serial remark code and the serial reference
3168 processing closures.
3169
3170 The value of is_serial must be false when do_marking_step is
3171 being called by any of the worker threads in a work gang.
3172 Examples include the concurrent marking code (CMMarkingTask),
3173 the MT remark code, and the MT reference processing closures.
3174
3175 *****************************************************************************/
3176
3177 void CMTask::do_marking_step(double time_target_ms,
3178 bool do_termination,
3179 bool is_serial) {
3180 assert(time_target_ms >= 1.0, "minimum granularity is 1ms");
3181 assert(concurrent() == _cm->concurrent(), "they should be the same");
3182
3183 G1CollectorPolicy* g1_policy = _g1h->g1_policy();
3184 assert(_task_queues != NULL, "invariant");
3185 assert(_task_queue != NULL, "invariant");
3186 assert(_task_queues->queue(_worker_id) == _task_queue, "invariant");
3187
3188 assert(!_claimed,
3189 "only one thread should claim this task at any one time");
3190
3191 // OK, this doesn't safeguard again all possible scenarios, as it is
3192 // possible for two threads to set the _claimed flag at the same
3193 // time. But it is only for debugging purposes anyway and it will
3194 // catch most problems.
3195 _claimed = true;
3196
3197 _start_time_ms = os::elapsedVTime() * 1000.0;
3198
3199 // If do_stealing is true then do_marking_step will attempt to
3200 // steal work from the other CMTasks. It only makes sense to
3201 // enable stealing when the termination protocol is enabled
3202 // and do_marking_step() is not being called serially.
3203 bool do_stealing = do_termination && !is_serial;
3204
3205 double diff_prediction_ms = _g1h->g1_policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
3206 _time_target_ms = time_target_ms - diff_prediction_ms;
3207
3208 // set up the variables that are used in the work-based scheme to
3209 // call the regular clock method
3210 _words_scanned = 0;
3211 _refs_reached = 0;
3212 recalculate_limits();
3213
3214 // clear all flags
3215 clear_has_aborted();
3216 _has_timed_out = false;
3217 _draining_satb_buffers = false;
3218
3219 ++_calls;
3220
3221 // Set up the bitmap and oop closures. Anything that uses them is
3222 // eventually called from this method, so it is OK to allocate these
3223 // statically.
3224 CMBitMapClosure bitmap_closure(this, _cm, _nextMarkBitMap);
3225 G1CMOopClosure cm_oop_closure(_g1h, _cm, this);
3226 set_cm_oop_closure(&cm_oop_closure);
3227
3228 if (_cm->has_overflown()) {
3229 // This can happen if the mark stack overflows during a GC pause
3230 // and this task, after a yield point, restarts. We have to abort
3231 // as we need to get into the overflow protocol which happens
3232 // right at the end of this task.
3233 set_has_aborted();
3234 }
3235
3236 // First drain any available SATB buffers. After this, we will not
3237 // look at SATB buffers before the next invocation of this method.
3238 // If enough completed SATB buffers are queued up, the regular clock
3239 // will abort this task so that it restarts.
3240 drain_satb_buffers();
3241 // ...then partially drain the local queue and the global stack
3242 drain_local_queue(true);
3243 drain_global_stack(true);
3244
3245 do {
3246 if (!has_aborted() && _curr_region != NULL) {
3247 // This means that we're already holding on to a region.
3248 assert(_finger != NULL, "if region is not NULL, then the finger "
3249 "should not be NULL either");
3250
3251 // We might have restarted this task after an evacuation pause
3252 // which might have evacuated the region we're holding on to
3253 // underneath our feet. Let's read its limit again to make sure
3254 // that we do not iterate over a region of the heap that
3255 // contains garbage (update_region_limit() will also move
3256 // _finger to the start of the region if it is found empty).
3257 update_region_limit();
3258 // We will start from _finger not from the start of the region,
3259 // as we might be restarting this task after aborting half-way
3260 // through scanning this region. In this case, _finger points to
3261 // the address where we last found a marked object. If this is a
3262 // fresh region, _finger points to start().
3263 MemRegion mr = MemRegion(_finger, _region_limit);
3264
3265 assert(!_curr_region->is_humongous() || mr.start() == _curr_region->bottom(),
3266 "humongous regions should go around loop once only");
3267
3268 // Some special cases:
3269 // If the memory region is empty, we can just give up the region.
3270 // If the current region is humongous then we only need to check
3271 // the bitmap for the bit associated with the start of the object,
3272 // scan the object if it's live, and give up the region.
3273 // Otherwise, let's iterate over the bitmap of the part of the region
3274 // that is left.
3275 // If the iteration is successful, give up the region.
3276 if (mr.is_empty()) {
3277 giveup_current_region();
3278 regular_clock_call();
3279 } else if (_curr_region->is_humongous() && mr.start() == _curr_region->bottom()) {
3280 if (_nextMarkBitMap->isMarked(mr.start())) {
3281 // The object is marked - apply the closure
3282 BitMap::idx_t offset = _nextMarkBitMap->heapWordToOffset(mr.start());
3283 bitmap_closure.do_bit(offset);
3284 }
3285 // Even if this task aborted while scanning the humongous object
3286 // we can (and should) give up the current region.
3287 giveup_current_region();
3288 regular_clock_call();
3289 } else if (_nextMarkBitMap->iterate(&bitmap_closure, mr)) {
3290 giveup_current_region();
3291 regular_clock_call();
3292 } else {
3293 assert(has_aborted(), "currently the only way to do so");
3294 // The only way to abort the bitmap iteration is to return
3295 // false from the do_bit() method. However, inside the
3296 // do_bit() method we move the _finger to point to the
3297 // object currently being looked at. So, if we bail out, we
3298 // have definitely set _finger to something non-null.
3299 assert(_finger != NULL, "invariant");
3300
3301 // Region iteration was actually aborted. So now _finger
3302 // points to the address of the object we last scanned. If we
3303 // leave it there, when we restart this task, we will rescan
3304 // the object. It is easy to avoid this. We move the finger by
3305 // enough to point to the next possible object header (the
3306 // bitmap knows by how much we need to move it as it knows its
3307 // granularity).
3308 assert(_finger < _region_limit, "invariant");
3309 HeapWord* new_finger = _nextMarkBitMap->nextObject(_finger);
3310 // Check if bitmap iteration was aborted while scanning the last object
3311 if (new_finger >= _region_limit) {
3312 giveup_current_region();
3313 } else {
3314 move_finger_to(new_finger);
3315 }
3316 }
3317 }
3318 // At this point we have either completed iterating over the
3319 // region we were holding on to, or we have aborted.
3320
3321 // We then partially drain the local queue and the global stack.
3322 // (Do we really need this?)
3323 drain_local_queue(true);
3324 drain_global_stack(true);
3325
3326 // Read the note on the claim_region() method on why it might
3327 // return NULL with potentially more regions available for
3328 // claiming and why we have to check out_of_regions() to determine
3329 // whether we're done or not.
3330 while (!has_aborted() && _curr_region == NULL && !_cm->out_of_regions()) {
3331 // We are going to try to claim a new region. We should have
3332 // given up on the previous one.
3333 // Separated the asserts so that we know which one fires.
3334 assert(_curr_region == NULL, "invariant");
3335 assert(_finger == NULL, "invariant");
3336 assert(_region_limit == NULL, "invariant");
3337 HeapRegion* claimed_region = _cm->claim_region(_worker_id);
3338 if (claimed_region != NULL) {
3339 // Yes, we managed to claim one
3340 setup_for_region(claimed_region);
3341 assert(_curr_region == claimed_region, "invariant");
3342 }
3343 // It is important to call the regular clock here. It might take
3344 // a while to claim a region if, for example, we hit a large
3345 // block of empty regions. So we need to call the regular clock
3346 // method once round the loop to make sure it's called
3347 // frequently enough.
3348 regular_clock_call();
3349 }
3350
3351 if (!has_aborted() && _curr_region == NULL) {
3352 assert(_cm->out_of_regions(),
3353 "at this point we should be out of regions");
3354 }
3355 } while ( _curr_region != NULL && !has_aborted());
3356
3357 if (!has_aborted()) {
3358 // We cannot check whether the global stack is empty, since other
3359 // tasks might be pushing objects to it concurrently.
3360 assert(_cm->out_of_regions(),
3361 "at this point we should be out of regions");
3362 // Try to reduce the number of available SATB buffers so that
3363 // remark has less work to do.
3364 drain_satb_buffers();
3365 }
3366
3367 // Since we've done everything else, we can now totally drain the
3368 // local queue and global stack.
3369 drain_local_queue(false);
3370 drain_global_stack(false);
3371
3372 // Attempt at work stealing from other task's queues.
3373 if (do_stealing && !has_aborted()) {
3374 // We have not aborted. This means that we have finished all that
3375 // we could. Let's try to do some stealing...
3376
3377 // We cannot check whether the global stack is empty, since other
3378 // tasks might be pushing objects to it concurrently.
3379 assert(_cm->out_of_regions() && _task_queue->size() == 0,
3380 "only way to reach here");
3381 while (!has_aborted()) {
3382 oop obj;
3383 if (_cm->try_stealing(_worker_id, &_hash_seed, obj)) {
3384 assert(_nextMarkBitMap->isMarked((HeapWord*) obj),
3385 "any stolen object should be marked");
3386 scan_object(obj);
3387
3388 // And since we're towards the end, let's totally drain the
3389 // local queue and global stack.
3390 drain_local_queue(false);
3391 drain_global_stack(false);
3392 } else {
3393 break;
3394 }
3395 }
3396 }
3397
3398 // We still haven't aborted. Now, let's try to get into the
3399 // termination protocol.
3400 if (do_termination && !has_aborted()) {
3401 // We cannot check whether the global stack is empty, since other
3402 // tasks might be concurrently pushing objects on it.
3403 // Separated the asserts so that we know which one fires.
3404 assert(_cm->out_of_regions(), "only way to reach here");
3405 assert(_task_queue->size() == 0, "only way to reach here");
3406 _termination_start_time_ms = os::elapsedVTime() * 1000.0;
3407
3408 // The CMTask class also extends the TerminatorTerminator class,
3409 // hence its should_exit_termination() method will also decide
3410 // whether to exit the termination protocol or not.
3411 bool finished = (is_serial ||
3412 _cm->terminator()->offer_termination(this));
3413 double termination_end_time_ms = os::elapsedVTime() * 1000.0;
3414 _termination_time_ms +=
3415 termination_end_time_ms - _termination_start_time_ms;
3416
3417 if (finished) {
3418 // We're all done.
3419
3420 if (_worker_id == 0) {
3421 // let's allow task 0 to do this
3422 if (concurrent()) {
3423 assert(_cm->concurrent_marking_in_progress(), "invariant");
3424 // we need to set this to false before the next
3425 // safepoint. This way we ensure that the marking phase
3426 // doesn't observe any more heap expansions.
3427 _cm->clear_concurrent_marking_in_progress();
3428 }
3429 }
3430
3431 // We can now guarantee that the global stack is empty, since
3432 // all other tasks have finished. We separated the guarantees so
3433 // that, if a condition is false, we can immediately find out
3434 // which one.
3435 guarantee(_cm->out_of_regions(), "only way to reach here");
3436 guarantee(_cm->mark_stack_empty(), "only way to reach here");
3437 guarantee(_task_queue->size() == 0, "only way to reach here");
3438 guarantee(!_cm->has_overflown(), "only way to reach here");
3439 guarantee(!_cm->mark_stack_overflow(), "only way to reach here");
3440 } else {
3441 // Apparently there's more work to do. Let's abort this task. It
3442 // will restart it and we can hopefully find more things to do.
3443 set_has_aborted();
3444 }
3445 }
3446
3447 // Mainly for debugging purposes to make sure that a pointer to the
3448 // closure which was statically allocated in this frame doesn't
3449 // escape it by accident.
3450 set_cm_oop_closure(NULL);
3451 double end_time_ms = os::elapsedVTime() * 1000.0;
3452 double elapsed_time_ms = end_time_ms - _start_time_ms;
3453 // Update the step history.
3454 _step_times_ms.add(elapsed_time_ms);
3455
3456 if (has_aborted()) {
3457 // The task was aborted for some reason.
3458 if (_has_timed_out) {
3459 double diff_ms = elapsed_time_ms - _time_target_ms;
3460 // Keep statistics of how well we did with respect to hitting
3461 // our target only if we actually timed out (if we aborted for
3462 // other reasons, then the results might get skewed).
3463 _marking_step_diffs_ms.add(diff_ms);
3464 }
3465
3466 if (_cm->has_overflown()) {
3467 // This is the interesting one. We aborted because a global
3468 // overflow was raised. This means we have to restart the
3469 // marking phase and start iterating over regions. However, in
3470 // order to do this we have to make sure that all tasks stop
3471 // what they are doing and re-initialize in a safe manner. We
3472 // will achieve this with the use of two barrier sync points.
3473
3474 if (!is_serial) {
3475 // We only need to enter the sync barrier if being called
3476 // from a parallel context
3477 _cm->enter_first_sync_barrier(_worker_id);
3478
3479 // When we exit this sync barrier we know that all tasks have
3480 // stopped doing marking work. So, it's now safe to
3481 // re-initialize our data structures. At the end of this method,
3482 // task 0 will clear the global data structures.
3483 }
3484
3485 // We clear the local state of this task...
3486 clear_region_fields();
3487
3488 if (!is_serial) {
3489 // ...and enter the second barrier.
3490 _cm->enter_second_sync_barrier(_worker_id);
3491 }
3492 // At this point, if we're during the concurrent phase of
3493 // marking, everything has been re-initialized and we're
3494 // ready to restart.
3495 }
3496 }
3497
3498 _claimed = false;
3499 }
3500
3501 CMTask::CMTask(uint worker_id,
3502 ConcurrentMark* cm,
3503 size_t* marked_bytes,
3504 BitMap* card_bm,
3505 CMTaskQueue* task_queue,
3506 CMTaskQueueSet* task_queues)
3507 : _g1h(G1CollectedHeap::heap()),
3508 _worker_id(worker_id), _cm(cm),
3509 _claimed(false),
3510 _nextMarkBitMap(NULL), _hash_seed(17),
3511 _task_queue(task_queue),
3512 _task_queues(task_queues),
3513 _cm_oop_closure(NULL),
3514 _marked_bytes_array(marked_bytes),
3515 _card_bm(card_bm) {
3516 guarantee(task_queue != NULL, "invariant");
3517 guarantee(task_queues != NULL, "invariant");
3518
3519 _marking_step_diffs_ms.add(0.5);
3520 }
3521
3522 // These are formatting macros that are used below to ensure
3523 // consistent formatting. The *_H_* versions are used to format the
3524 // header for a particular value and they should be kept consistent
3525 // with the corresponding macro. Also note that most of the macros add
3526 // the necessary white space (as a prefix) which makes them a bit
3527 // easier to compose.
3528
3529 // All the output lines are prefixed with this string to be able to
3530 // identify them easily in a large log file.
3531 #define G1PPRL_LINE_PREFIX "###"
3532
3533 #define G1PPRL_ADDR_BASE_FORMAT " " PTR_FORMAT "-" PTR_FORMAT
3534 #ifdef _LP64
3535 #define G1PPRL_ADDR_BASE_H_FORMAT " %37s"
3536 #else // _LP64
3537 #define G1PPRL_ADDR_BASE_H_FORMAT " %21s"
3538 #endif // _LP64
3539
3540 // For per-region info
3541 #define G1PPRL_TYPE_FORMAT " %-4s"
3542 #define G1PPRL_TYPE_H_FORMAT " %4s"
3543 #define G1PPRL_BYTE_FORMAT " " SIZE_FORMAT_W(9)
3544 #define G1PPRL_BYTE_H_FORMAT " %9s"
3545 #define G1PPRL_DOUBLE_FORMAT " %14.1f"
3546 #define G1PPRL_DOUBLE_H_FORMAT " %14s"
3547
3548 // For summary info
3549 #define G1PPRL_SUM_ADDR_FORMAT(tag) " " tag ":" G1PPRL_ADDR_BASE_FORMAT
3550 #define G1PPRL_SUM_BYTE_FORMAT(tag) " " tag ": " SIZE_FORMAT
3551 #define G1PPRL_SUM_MB_FORMAT(tag) " " tag ": %1.2f MB"
3552 #define G1PPRL_SUM_MB_PERC_FORMAT(tag) G1PPRL_SUM_MB_FORMAT(tag) " / %1.2f %%"
3553
3554 G1PrintRegionLivenessInfoClosure::
3555 G1PrintRegionLivenessInfoClosure(const char* phase_name)
3556 : _total_used_bytes(0), _total_capacity_bytes(0),
3557 _total_prev_live_bytes(0), _total_next_live_bytes(0),
3558 _hum_used_bytes(0), _hum_capacity_bytes(0),
3559 _hum_prev_live_bytes(0), _hum_next_live_bytes(0),
3560 _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
3561 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3562 MemRegion g1_reserved = g1h->g1_reserved();
3563 double now = os::elapsedTime();
3564
3565 // Print the header of the output.
3566 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
3567 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX" HEAP"
3568 G1PPRL_SUM_ADDR_FORMAT("reserved")
3569 G1PPRL_SUM_BYTE_FORMAT("region-size"),
3570 p2i(g1_reserved.start()), p2i(g1_reserved.end()),
3571 HeapRegion::GrainBytes);
3572 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3573 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3574 G1PPRL_TYPE_H_FORMAT
3575 G1PPRL_ADDR_BASE_H_FORMAT
3576 G1PPRL_BYTE_H_FORMAT
3577 G1PPRL_BYTE_H_FORMAT
3578 G1PPRL_BYTE_H_FORMAT
3579 G1PPRL_DOUBLE_H_FORMAT
3580 G1PPRL_BYTE_H_FORMAT
3581 G1PPRL_BYTE_H_FORMAT,
3582 "type", "address-range",
3583 "used", "prev-live", "next-live", "gc-eff",
3584 "remset", "code-roots");
3585 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3586 G1PPRL_TYPE_H_FORMAT
3587 G1PPRL_ADDR_BASE_H_FORMAT
3588 G1PPRL_BYTE_H_FORMAT
3589 G1PPRL_BYTE_H_FORMAT
3590 G1PPRL_BYTE_H_FORMAT
3591 G1PPRL_DOUBLE_H_FORMAT
3592 G1PPRL_BYTE_H_FORMAT
3593 G1PPRL_BYTE_H_FORMAT,
3594 "", "",
3595 "(bytes)", "(bytes)", "(bytes)", "(bytes/ms)",
3596 "(bytes)", "(bytes)");
3597 }
3598
3599 // It takes as a parameter a reference to one of the _hum_* fields, it
3600 // deduces the corresponding value for a region in a humongous region
3601 // series (either the region size, or what's left if the _hum_* field
3602 // is < the region size), and updates the _hum_* field accordingly.
3603 size_t G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* hum_bytes) {
3604 size_t bytes = 0;
3605 // The > 0 check is to deal with the prev and next live bytes which
3606 // could be 0.
3607 if (*hum_bytes > 0) {
3608 bytes = MIN2(HeapRegion::GrainBytes, *hum_bytes);
3609 *hum_bytes -= bytes;
3610 }
3611 return bytes;
3612 }
3613
3614 // It deduces the values for a region in a humongous region series
3615 // from the _hum_* fields and updates those accordingly. It assumes
3616 // that that _hum_* fields have already been set up from the "starts
3617 // humongous" region and we visit the regions in address order.
3618 void G1PrintRegionLivenessInfoClosure::get_hum_bytes(size_t* used_bytes,
3619 size_t* capacity_bytes,
3620 size_t* prev_live_bytes,
3621 size_t* next_live_bytes) {
3622 assert(_hum_used_bytes > 0 && _hum_capacity_bytes > 0, "pre-condition");
3623 *used_bytes = get_hum_bytes(&_hum_used_bytes);
3624 *capacity_bytes = get_hum_bytes(&_hum_capacity_bytes);
3625 *prev_live_bytes = get_hum_bytes(&_hum_prev_live_bytes);
3626 *next_live_bytes = get_hum_bytes(&_hum_next_live_bytes);
3627 }
3628
3629 bool G1PrintRegionLivenessInfoClosure::doHeapRegion(HeapRegion* r) {
3630 const char* type = r->get_type_str();
3631 HeapWord* bottom = r->bottom();
3632 HeapWord* end = r->end();
3633 size_t capacity_bytes = r->capacity();
3634 size_t used_bytes = r->used();
3635 size_t prev_live_bytes = r->live_bytes();
3636 size_t next_live_bytes = r->next_live_bytes();
3637 double gc_eff = r->gc_efficiency();
3638 size_t remset_bytes = r->rem_set()->mem_size();
3639 size_t strong_code_roots_bytes = r->rem_set()->strong_code_roots_mem_size();
3640
3641 if (r->is_starts_humongous()) {
3642 assert(_hum_used_bytes == 0 && _hum_capacity_bytes == 0 &&
3643 _hum_prev_live_bytes == 0 && _hum_next_live_bytes == 0,
3644 "they should have been zeroed after the last time we used them");
3645 // Set up the _hum_* fields.
3646 _hum_capacity_bytes = capacity_bytes;
3647 _hum_used_bytes = used_bytes;
3648 _hum_prev_live_bytes = prev_live_bytes;
3649 _hum_next_live_bytes = next_live_bytes;
3650 get_hum_bytes(&used_bytes, &capacity_bytes,
3651 &prev_live_bytes, &next_live_bytes);
3652 end = bottom + HeapRegion::GrainWords;
3653 } else if (r->is_continues_humongous()) {
3654 get_hum_bytes(&used_bytes, &capacity_bytes,
3655 &prev_live_bytes, &next_live_bytes);
3656 assert(end == bottom + HeapRegion::GrainWords, "invariant");
3657 }
3658
3659 _total_used_bytes += used_bytes;
3660 _total_capacity_bytes += capacity_bytes;
3661 _total_prev_live_bytes += prev_live_bytes;
3662 _total_next_live_bytes += next_live_bytes;
3663 _total_remset_bytes += remset_bytes;
3664 _total_strong_code_roots_bytes += strong_code_roots_bytes;
3665
3666 // Print a line for this particular region.
3667 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3668 G1PPRL_TYPE_FORMAT
3669 G1PPRL_ADDR_BASE_FORMAT
3670 G1PPRL_BYTE_FORMAT
3671 G1PPRL_BYTE_FORMAT
3672 G1PPRL_BYTE_FORMAT
3673 G1PPRL_DOUBLE_FORMAT
3674 G1PPRL_BYTE_FORMAT
3675 G1PPRL_BYTE_FORMAT,
3676 type, p2i(bottom), p2i(end),
3677 used_bytes, prev_live_bytes, next_live_bytes, gc_eff,
3678 remset_bytes, strong_code_roots_bytes);
3679
3680 return false;
3681 }
3682
3683 G1PrintRegionLivenessInfoClosure::~G1PrintRegionLivenessInfoClosure() {
3684 // add static memory usages to remembered set sizes
3685 _total_remset_bytes += HeapRegionRemSet::fl_mem_size() + HeapRegionRemSet::static_mem_size();
3686 // Print the footer of the output.
3687 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX);
3688 log_trace(gc, liveness)(G1PPRL_LINE_PREFIX
3689 " SUMMARY"
3690 G1PPRL_SUM_MB_FORMAT("capacity")
3691 G1PPRL_SUM_MB_PERC_FORMAT("used")
3692 G1PPRL_SUM_MB_PERC_FORMAT("prev-live")
3693 G1PPRL_SUM_MB_PERC_FORMAT("next-live")
3694 G1PPRL_SUM_MB_FORMAT("remset")
3695 G1PPRL_SUM_MB_FORMAT("code-roots"),
3696 bytes_to_mb(_total_capacity_bytes),
3697 bytes_to_mb(_total_used_bytes),
3698 perc(_total_used_bytes, _total_capacity_bytes),
3699 bytes_to_mb(_total_prev_live_bytes),
3700 perc(_total_prev_live_bytes, _total_capacity_bytes),
3701 bytes_to_mb(_total_next_live_bytes),
3702 perc(_total_next_live_bytes, _total_capacity_bytes),
3703 bytes_to_mb(_total_remset_bytes),
3704 bytes_to_mb(_total_strong_code_roots_bytes));
3705 }